Hydrostatic Transmissions for Heavy Autovehicules

8/12/2019 Hydrostatic Transmissions for Heavy Autovehicules

1/128

George Niculescu Transmissions hydrostatiques pour les autovhicules lourds

1

Hydrostatic Transmissions for heavy autovehicules


2/128


2

Thanks:

During the work of this license, men Nicolae Vasiliu and Bogdan Mihalescu were near

me with advice and opinions. It is a new work for me, I have chosen HYDROSTATIC

TRANSMISSION FOR AUTOVEHICULES HEAVY because that is something new for me, with

the patience of Mr. Vasiliu i succeeded in understanding and mastering the subject, subject

which in my opinion represents a subject of the future. We must mention here also my

family which has been close to me during the faculty and the last session of examinations

and obviously during the work of license.


3/128


3

Chapter 1

Hydrostatic Transmissions for heavy autovehicules

General information:

1. Introduction:The field of use: the main transmission of a autovehicul heavy.

In a hydraulic transmission, a pump converts the mechanical energy given by the car

traction into hydraulic energy. It is creeps into mechanical energy using a hydraulic motor

which switched on the utilage has work.

The structure of the transmissions tires is similar: a compressor switched on by a car of

traction which allimente gas with an air motor which turned on the tooling to work.

There is also has been limiting of pneumatic actuation trained in gasoline by generatoires

of gas engines and tires, as in the case of dirigement for snowshoes.

The setttings mechanical energy given by this type of transmissions may be

rule continuessement in large limits and with relatively simple means. The flexibility is a key

benefit of hydraulic transmissions and tires compared to the mechanical transmissions, in

the reassuring a wide use, even below their operating principle involves randaments

relatively weak.

By report of the type of cars used hydraulic, transmissions hidrauliques can be:

-Hydrostatic (volumetric)

-Hydrodynamic or Hydrosoniques

If the hydraulic cars (the pump & engine) which constituted the fundamental elements of

the hydraulic transmission, are of the positive displacement type,then the transmission is


4/128


4

called HYDROSTATICVOLUMETRIC or because the mechanical energy given by the machine

of force is used by a positive displacement pump virtually just for the increase of the energy

of transmission fluid pressure; the latter is after ca transformed into mechanical energy by a

hydraulic motor by volume.

Fig. 1.4 . The schema of a hydrostatic transmission:

The term hydrostatic is unfit (the transmission of energy is done by the circulation of a

liquid which has the assistance of several gears adjustment items and key protection

speeds orders of cents m/s) but it is widely used in practice.

In the case of use of a centrifugal pump and has a hydraulic pump, the transmission iscalled hydrodynamic, because during the transformations the energy variation of the

kinetic energy of the liquid is comparable with that of the pressure energy.

HRT - hydrostatic transmission; BCRP - control block adjustment and

protection; PV - volumetric pump; MV - engine by volume; SLP - pressure

control valve; ML - work machine; EM - electromoteur.


5/128


5

Fig 1.5 schematic of a transmission hydrodinamique

PCF - centrifugal pump

TCP - centripetal turbine

BR - adjustment block THD - transmission hydrodinamique

Fig 1.6 Schema of a sonic transmission:

1 - Pump 2 sonic - sonic Engine

THE inventateur of sonic transmissions is the Romanian engineer Gogu

Constantinescu, who has applied his invention in the military field. The most important

application of his invention represents the injection pump for the Diesel engine, lost solutin

was present.

The transmissions "pneumostatiques"use of pneumatic machines and volumetric those

"pneumodinamiques" - turbomachinery tires,in existing solutions also mixed (volumetric

compressor-turbine pneumatic.


6/128


6

1.2CLASSIFICATION OF T RANSMISSIONS Hydraulic and PneumaticThe hydraulic transmissions and tires is distinguished from the point of view theory

has been limiting plcs, systems of actuation,has been limiting control and setting

automat.

These syshtemes of actuation and hydrostatic control and pneumostatique are has

been limiting has open circuit,therefore,the input variable which decides the de Rgim of

operation of the interlock is not influenced by the effect of its action. has caused

disruption inerentes the greatness of output cannot be this descipline univoc with the

input variable. OF habits they transmit of the major powers, their randament is an

important parameter, used necessarily compared to other types of transmissions.

Has been limiting the hydrostatic control and pneumostatiques transmit in general of

small powers, and their engines operate on the "death squad" consists of command

other transmissions much more powerful.

The has been limiting of adjusting automat hydrosatitques and pneumostatiques are has

been limiting to circuit closed, therefore they contain a link reaction which allows the

comparison continued or intermittent in the input variable by report has the greatness of

output. The difference of them represents the error is constitutes the control signal of

the amplifier of the systhem which allimente the ellement of execution with the aim of

fix itself the herreur aparue. It is like ca that the precission of these has been limiting is

high. In de Rgim stationar, therelationship between the input variable that of output is

virtually one relationship.

The usuals parameters are:

-The position

-The angular speed (liniare)

-The time of the shaft (the power of the rod) of the hydrostatic motor/pneumostatique

-The power dissipated by the transmission


7/128


7

1.3 THE ADVANTAGES AND DISADVANTAGES OF HYDRAULIC TRANSMISSIONS AND

TIRES

The hydraulic transmissions and tires have some specific caractheristiques which make

the difference compared to other types of transmissions, as ca is explained their spread

and also their restrictions in the use. The places of transmissions hidrauliques and tires in

the framework of the transmissions can be established after several citerres practical in

nature.

1.3.1 Benefits

1) The possibility of amplassement of hydraulic motors volume in a position are done inrelation to the cars of force constitutes a major advantage of hydraulic transmission

compared to mechanical transmissions by simplifying the considerable projection of

cars to work.

2) The control elements of hydraulic transmissions whenthe to operators of forces ormoments reduced and can be amplasees in spaces suitable ,giving the accord

because for a certain level of ergonomics.

3) The torque available by the motors rotating electrical is proportional with theintensity of the electric current, being limited by the warming of the insulation and

by the saturation of the magnetic circuit.

The torque given by the hydraulic motors rotary volumetric and

_____PROPORTIONAL with the pressure difference existing between the fittings

energy, being limited only by the resistance of the materials used (effort allowable

materials used)

4) The heat generated by the internal losses and which limit the performance of eachcar is taken by the liquid of transmission is transferred to the environment by a heat

exchanger. The volumetric machines usually have specific powers superrieures has

1kW/kg).

5) The liquids are used in the hydraulic transmission typical also provide the rol oflubricant, ensuring also a superior reliability.

6) The motors rotary volumetric can work on a large game of revolutions ( RPM ). Theminimum value established depends on in relation to the type of mechanism used for


8/128


8

the realization of the rooms and precission of execution. has caused losses given

existing very small the randament of volumetric engines has the high values and the

caractheristique mechanical (M-n) has a Pant reduced which gives these engines a

high rigidity static (the fall of RPM by report to rezistents moments and very small).

Regarding the plcs has been limiting adjustment of position,this quality ensures a

precission specialand a reduced sensitivity to disturbances.

7) The motors rotating electrical realize a proportional link between the voltage ( U )and the rotations per minut ( RPM ) and the relation between the time activ and the

moment of inertia of componantes mobile has a reduced value.

The motors rotary volumetric give Po a stripe on the right between the flow and the

Angular speed and the ratio between the time activ and the inertia of the moving

parts and very large,of here resulted in the capacity of these engines to stop, start or

change direction, very fast.

In large the hydraulic transmission provide a large amplification in power (dpv useful

power/control power) and a good frequency response, has sufficient merit for

applications usual practices.

8) The engine volumetric hydraulic liniares permits to achieve considerable forces, for atemplate vraiemont reduces/small, because of the great pressure of work.

The leaks of volumetric engines are very grandchildren than,

it is as ca that their randament by volume is close to the unit, the minimal

speed established is very reduced and the rigidity static very large.Fig 1.8 . The

schematic diagram of a hydraulic systhem linked with a systhemTo hydraulic

actuation: MF - machine of force; SCH - systhem of hydraulic control; CHSERE -

hydraulic cylinder has simple effect and elastic regression; SRP - adjusting valve(limitation) of the pressure; SAH - syshtem of hydraulic actuation; ML - work machine


9/128


9

The adjustment of the parameters of fonctionales volumetric engines is relatively simple fact in utilisand pumps

or adjustable resistors adjustable hydraulic.

The hydraulic transmissions can be conducted with programs plcs

9) or computersindustriales has the assistance of amplifiers eh (eh contollers with a large

amplification factor in power) . This advantage is widely valorifie in present in the

field of machine tools, robots industrials was sold, in the aerospace technical energy

in.The development has been limiting control se am optimum by electronic means,

and the execution of commands by hydraulic track (nervs electronic+hydraulic

muscles). The storage of hydraulic power am simple,

in pneumatic accumulators.The volumetric engines rotativs have

as adversaries the electric motors, especially in the case of tooling mobile or the

template and the mass of componantes must be at a minimum. The engines

volumetric liniares are used in all the applications or are involved in large forces.

Pneumatic Motors volume are compact,

10)this advantage is valorifie in special in the case of portable tools. The possibility ofusing this type of engines in factories is favored because of the existence of the

compressed air.The adjustment of speed and torque of the pneumatic motors

volume can be achieved simply without having a lot of worries.

11)These engines can work automatic has the help of some logical elements.Ecologicalbeing juxtaposed,

nonpolluantes, pneumatic motors volumetric if use in facilities "green" has specific

industry allimentaire, chemical, mining, oil and energy.The use on a large scale of


10/128


10

hydraulic transmissions and tires gives the possibility of standardization and

unification of

12) their elements. The manufacture of large series in the specialized enterprises cansignificantly reduce the cost by ensuring at the same time a high

quality.1.3.2 DSAVANTAGES

The hydraulic transmissions are expensive because they involve out of pumps and

motors volumetric, elements of control, adjustment and protection, storage

elements, filtration and transport of liquid. The majority

1) of these componantes implies a precission running very high (specific to themechanical fine), materials and technologies nonconventionelles" to ensure the

precission the randament and the safety fonctionale imposed.The power losses which

aparraisent in concurrent use of energy transformation of hydraulic machines

volumetric, and also the elements of po, adjusting and protection, have

2) a amprente semnificative on the randament global machines of work equipped byhydraulic transmissions.The hydraulic transmission are poluantes in cases where

there are leaks, there is also the danger of losing all the liquid due to the leak of

sealing of a single element.The broillard causes formed in case of leakage of

3) high pressure by cracks and very flammable has cause of componantes volatilehydrocarbons which constitute the basis of

4) the majority of liquids used in hydraulic transmissions.The danger of self-inflamationof the liquid or loss of its lubricating quality limit the temperature of suited ofhydraulic transmissions. This disadvantage can be eliminated by using liquids of high

temperature or more liquid requests non-inflamables.

5) The contamination of the fluid in the transmission determines the main cause of thepremature wear of hydraulic transmissions. In cases where the particles of

contamination are abrasive,

6) the randament of the transmission decreases dramatically because of the increasedclearances. The bouchement of control orifices of the adjustment items

provide reported control false which can cause serious accidents.In cases where the


11/128


11

air between in a hydraulic systhem it generates oscillations which has serious

consequences

7) on the randament hydraulic installation.The maintenance and service of hydraulictransmissions need a special qualification, superrieure to other

8) types of transmissions.The complexity of the methods of analysis and synthesis ofhydraulic transmissions do not allow the development of a projection accessible

without having a superior preparation.The main disadvantage of PNEUMATIC

transmission is represented by the randament reduces.

9) The choice optim of a transmission for the concrete conditions passives in principle aproblem of nature techno-economic which requires high knowledge of all

10) possible caractheristiques.1.3.3 The hydrostatic transmissions and the news:

In the systhems of conventional transmission, the speed of the rotor is controlled by

a converter of frequency and by a transformer. The solution of ChapDrive controls the

speed of rotation of the rotor with a hydraulic pump and an engine, before the generator,

in utilsand of programmig solenoid valves by a computer, which changed to pump, motor,

or both during the nanoseconds and move the shaft of the turbine.

The marriage hydraulic pump and motor can work on an infinite range of rates, and

that is what allows the transmission ChapDrive for having the ability to withstand the

continuous changes in the relation of transmission.


12/128


12

The difference between the rotation of the rotor and generator / minute, which for a

turbine of 3MW for example can vary from 1:300 for databases wind speeds , to 1:100 in

conditions of storm. This concept removes the transformer therefore the production of

electrical energy flows directly into the network.

Any is the variation of the wind, the speed of the generator and its output, remain constant,

while the fluctuations in torque and the extreme loads will be reduced.

This manierre the systhem worked with a variable transmission ratio of a manierre that it

reduces the loads and optimized energy capture, the systhem to control a variable speed, in

assurand the stability and effectiveness of the systhem and a better network stability.

Darius Snieckus, BristolPublished: Monday, April 30 2012

Voila here a technical drawing, a diagram outcome of a patent of invention, which uses a

hydrostatic transmission for a heolienne:

Chapter 2

THE LIQUIDS USED IN THE HYDRAULIC TRANSMISSIONS

The liquids used in the

energy circui ts and for the contro l of hydraul ic transmiss ions cicl ique suffer

signif icant variat ions in pr essure veloci ty and temperature, i t com e in contact

with various m ateria ls and may be exposed to f ie ld electro-magnet ic, radiat ion

nuc leares, etc.

The difficult conditions of use require the liquids fonctionales some quality such as

those of:

- Lubrication Viscosity therefore acceptable in any conditions of operation of the systhem
mailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ecemailto:[email protected]?subject=Comment%20on%20online%20article&body=http://www.rechargenews.com/business_area/innovation/article264440.ece


13/128


13


14/128


14

- Physical proprieties and stable chemical

-Compatibilities with the materials of the systhem

-Compressibility, volatility, trend of foam, density

-Thermal expansion coefficient

-Price and toxicity

Reduced

-Antioxidant qualities and dielectric

-Storage and Handling simpleAt present there is a wide range of liquids fonctionales,

belonging of the chemical point of view to several classes, but none has all the quality

necessares for a certain transmission. Therefore the choice of a liquid director-generalor

in general a compromise which ensures the essential requests but imposed restrictions

regarding the structure of the system and conditions of use. The data some note

concerning the choice of a fluid are:

-The range of temperatures of use and storage, normal

and accidentals-The range of pressures and depressions for which the fluid is subjected

in de Rgim normal and accidental

-The requests of certain materials or items componantes the systhem

-Requests for safety

-The conditions

economicIf several liquids satisfaient comparable these requests, the final choice is

determined by the satisfaction of other criteria.

2.2

Basic PROPERTIES OF FLUIDS FONCTIONALES


15/128


15

2.2.1

THE VISCOSITYThe viscosity is the property

of the fluids to oppose the deformations which do not constitute variations of their

volume, by the emergence of the efforts tangentiales. The force required to move a layer

of area A with the speed by report has a layer adiacente has a distance DN is proportional

with the area has with the gradient of the speed after the normal direction of

ecoullement,/DN (speed of deformation) and the dynamic viscosity of the fluid .

The SI unit of viscosity dynamic is Poiseuille 1Pl= 1kg m-1s-1

and

the CGS unit - poise: 1Po=1 g cm-1s-1. Recent studies concerning the term "viscosity

dn

duAF of dilation"

result, it can cause loss of energy when it is opposed to the fluids volume

variations without deformation.In practice we used the

kinematic viscosity defined by the ratio

between the dynamic viscosity and density of the liquid:

(2.2 )The SI unit of this magnitude is 1m2s-1 and in CGS is called stokes:1

Cst=10-2 St = 1 mm2s-1It also uses the units of measurement techniques which are not

corelees with the physical definition but with the measuring devices or with the

embarked upon to use such as: grades Engler(EUROPA) ; seconds Redwood(UK) ; seconds

Saybold(USA) and units Barbey(France). The conversion thereof

into centistokes is indicated in the graph:In calculations aproximatives we can use the

relationship


16/128


16

of transformation:

(2.3 )Fig 2.1 . The diagram

of conversion of units of measurement technique of the viscosity in centistokesThe

viscosity is a caractheristique essentiale of liquids fonctionales because it ensures the

flotation of the rafters, limit

the losses of liquid among the sealing elements and generates forces which dampen the

oscillations of fonctionales parameters, at the same time it causes energy losses in the

spaces among the moving parts relative and ducts, influence the characteristics of the

control orifices, etc.The viscosity of liquids decreases with temperature and increases but

not much, with the pressure. Has the high temperatures the internal leakage of the

hydraulic machine volume and distribution items decreased in a manner the prohibitory

randament of transmissions and the fall of the capacityof the bearing lubricating

pelicules can cause the sticking of the different mechanisms.

E104,7sm o612 The variation of the viscosity

of a coat with mineral pressureThe variation of the viscosity of the liquid AMG - 10


17/128


17

with the temperature The excessive viscosity occure has low temperatures and

generates large load losses who had created the difficulties

of suction(cavitation) at the pumps, reduces the speed of the motors and the randament

of hydraulic transmissions. These phenomena explain the major interest for liquids to

what the viscosity varies a little with the temperature. For the assessment of this

quality they have been proposed several indices of viscosity. The simplest of them is the

negative of the Pant geometric average of the curve of variation of the viscosity with

temperature, represented in programmig

log(log v) - T on a diagram of type ASTM (American Society

for

testing material standards on petroleum products and lubrificants) FIG 2.4 .The useful part

of this curve is v(T)


18/128


18

is in this system of coordinates reliable performer a straight line for the majority of liquids, permetand the

simple identification of a liquid optim from this point of view. FIG 2.4 The diagram

ASTM for liquids hydroliques commonplace.The most common method of measuring the viscosity

of a fluid by report has the temperature is the viscosity index DEAN-DAVIS, which is

defined with the relationship: (2.4 )There are two ranges of liquids as standard,

those nafteniques and parafiniques or it is considered two liquids that has 210 F = 100 C

have the same viscosity as the fluid considered in figure 2.5 .

It is noted with Np if


19/128


19

the oil viscosity naftenique, paraffinic and analisee has 100 F = 38 C. The standard oils

parafiniques have the index

of viscosity 100 and those nafteniques - 0 . The liquid is best from the point of view of

the viscosity

%100I N by report has the temperature if the viscosity

index

is greater. A few liquids hidrostatiques moderns have Iv> 100, therefore they are

superior by report has the just becasue of mineral oils.The variation of the viscositywith

temperature T[K] has the pressureatmosferique can be aproximee has using the

relationship:

(2.5 ) Or is a constant specific to each liquid, and T0- a temperature are done

for what it recognizes the viscosity of the liquid (T0). The typical value of is 0.015 K-

1 .In the interval of temperature


20/128


20

30 150oC for mineral oils we can use the relationship: (2.6 )

0TT0eTT Where n depends on the viscosity

50 of the oil has a temperature of t = 50 oC of after the curve:Fig 2.5 The diagram of

definition to the viscosity indexFig 2.5

The variation of the viscosity index of mineral oils by has 50 0CThe behavior of a liquid has

low temperatures is caractheriseby the temperature at which during the cooling it appear of

cristales(freezing point) and by the temperature at which the liquid begins to flow after a

warming consecutive to the freezing ( flow point ) . n

50t

50t

The liquids are unusable has of

temperaturesmuch larger than those of temperature characteristics, virtually we can say q'a

liquid cannot be used for viscositees which exceed 2000 CSE.The influence of pressure by

report has the viscosity may be regarded stripe on the right for pressures < 500 bar:The value of the

coefficient Kv

depends on the viscosity of the liquid. If 50


21/128


21

50 >15 cSt, KV= 0.003 .In case of large pressures on the growth of the viscosity with pressure is

exponential. For example between 1 and 2000bar the viscosityof mineral oils believes 50 has 100 times and that of

the synthetic oils of 15 has 25 times.

Concerning the pressure of 20,000 has 30.000bar mineral oils are solidified. The variation

of viscosity with temperature and pressure will lead to the continuous modification of

parameters fonctionals of hydraulic transmissions.

2.2.2 The QUALITES LUBRICANTSThe viscosity determines in large the quality of

lubricating liquid has the relative speeds large surfaces adiacentes, but does not

constitute the element decissiv has the low speeds and large loads when there is the

danger of sticking of the bearings. To prevent or to the reduction of the wear of the

bearings are used friction materials and introduced in the

lubricating liquid additives, to improve the quality

Kp1pp at of lubrication. The fatty acids, esters and

other organic components with a long catene contains the clor,

lead, and sulf stanium which aderent to metallic surfaces by preventing their contact. A

aditiv usual is the tricresilfosfat. The local temperatures high generated by the

microgripages, a few components halogenats is combined with the metals by forming

halogenats with a point of cast iron which reduces reflowed surfaces in relative

movement. These additives do not have the same eficacyte for for all liquids and have a

chemical stability reduced.

The quality of lubricating fluids are at using the devices that simulate the types of

bearings or with volumetric pumps. The loss of weight of the parts against unsolicited

advertising has the wear constitutes an index on the quality of lubricating liquid tested.In

our country the tested se font with a

ball of 12.25 mm which is pushed with a

certain constant force and setting in motion relative has 3 other balls identical bet

under a ver full of lubricant. The torque required was the rotation of the upper ball is

proportional with the coefficient of friction and the reduction of the diameters of the

lower ball is reversed proportional with the properties of lubricating fluid.2.2.3


22/128


22

THE DENSITY AND THE COMPRESSIBILIT=m/V * kg/m3 ]In normal conditions the

density of mineral oils is from 830 up to 940 kg/m3 . The density of synthetic fluids

depends on their chemical composition.

For the liquid silicones = 930 ..1030 kg/m3

and for the hidrocarbures clorinate =1538 kg/m3.

The density of liquids influence the weight of the hydraulic transmission, an important

parameter of mobile facilities. In de Rgim stationary pipe support the losses of loads by

of ports ( essential in the case of distribution items and adjusting ) are reversed

proportional valves are used with density. The variation of the density with the pressure

in transitional de Rgim product of mechanical oscillations which may be non-

depreciated.The density

of the liquid is in function of the pressure and temperature. Synthetic fluids dilate more

with the increase in the heat.

The variation of the density with the temperature must be considered

when calculating the volume of tanks. If they are open the increase in temperature can

cause the deversation of liquid. In the case of a closed tank full with the liquid the

difference between the coefficient of thermal expansion of the liquid and the tank

rcreate the suprapression who can detruir the tank:p=(-r)t or =coefficient of

expansion of the liquid

In the calculations practices the variation of the density of pure liquids with the pressure

can be neglected. For an overpressure of 200 bar the density of liquids fonctionales

believes with 1 .2 %.

The compressibility of the reduced liquid allows a prompt response of the instalation,

giving the hydraulic transmissions a high rigidity, at the same time it can

generate pressure shocks important in syshtemes distribution of hydraulic machines,

volumetric reduissent the volume flow rate of the pumps of high pressure and dimminiue


23/128


23

the randament of hydraulic transmission, because of the energy consomee to compress

the liquid in the pumps we pert the released of the liquid in the engines, after the

mechanical work util.In normal conditions the module of elasticity of the just becasue of

mineral oils is between 17,000 and 18,000 bar. The liquid synthetic fonctionales are in

general more elastic, for example, to the silicons in the same conditions the module of

elasticity = 10.000bar. liquids fonctionales has basis of H20 have an elasticity

appropriately from that of water of = 20.000bar.The modul of elasticity is influenced by

the pressure, temperature and the air present in the instalation. In the range of pressures

0 .500 bar reliable performer increases with the pressure: (p)=(pat)+p K

The value of the coefficient K depends on the liquid used and the temperature, formineral oils may be considered K=12.

During the increase of the temperature, the modul of elasticity decreases. For example

between 40 C and 200 C decreases in the case of mineral oils of 9000 has 10000 bar

and in the case of oils silicones it decays to 4200 bar.The air present in the facilities

decreased considerably the modul of elasticity of hydrostatic liquids.

2.2.4 The inflamabiliteThe main disadvantage of liquids fonctionales has basis of

hydrocarbons is represented by a fire protective measures shall be appropriate, pattern

which determines the continuous improvement of synthetic fluids. The fires caused by

the fumes of the open reservoirs or by the contact of the liquid with the hot surfaces of

the facilities (molten metals smelleders, the pots for engine exhaust, brake disks). The

measureas as an aid of posibilitees liquid use by report has this point of view is made

using trios temperatures characteristics.

The point of inflamabilite.

The liquid being prechaufe in a crucible, a flame "pilot" approach is periodically of its

surface free, the point of inflamabilite is represented by the temperature or has the what

it cover shutters appear a small flame. This temperature has the value for the mineral

oils, approximately 100


24/128


24

0C and 200 0C for the synthetic oils as the esters and the silicats. Concerning the

synthetic liquid non-inflamables this characteristic is not defined, but toward 100 0C they

are beginning to release toxic vapors.The temperature of brulement.

It is the temperature of the liquid has the what these vapuers continuet burning

smell after the abduction of the flame "pilot". Between this temperature is the point of

inflamabilite there is a difference of approximately 40 0C.

The temperature of autoinflamation.

It is established using a surface well heated on the what we

dropped a dripping of liquid which is spontaneously inflamme.

This temperature depends on the conditions of fold advantage, it

is approximately 250 0C for mineral oils and 400 0C for the esters

and silicats. Reliable Performer there is no liquids non-

inflamables, there is only liquids that can eliminate the risk of fire

or explosion in the usual conditions, liquid resistant has lights. not

to be confused with the liquids of high temperature which retain

their quality but are more flammable.2.2.5

Compatibility with the materials of the systhemThe main materials assigned by the

liquids fonctionales are the elastomers used in the manufacture of sealing elements

and fittings elastic.Mineral oils have replaced the vegetable oils such as liquid

fonctionales just after the elaboration of elastomers of synthesis, because they disolve

the cauchiuc natural. liquids non-inflamables of hydraulic transmissions of

aeronavesmodern have been used


25/128


25

only afterthe manufacture of butiles and etilpropilenes. Concerning liquids of high

pressure there is not yet a elastomer ideal.The sealing materials must be exclusive in relation to the fluid used

in the installation, the change of this fluid intake with him also the change of all

jountes sealing.At present there is not a universal systhem simulation of the

compatibility of elastomers with liquids. The seals of the liquids has basis of petrol are

tested using the aniline, the latter director-generalor reliable performer a mixture of

hydrocarbons that have as a consequence the growth in volume of elastomers. Each

torque liquid-sealing must be tested using a standard elastomer, with the gravimetric

measurement of the quantity of liquid absorbed.

We studied the relationship between the liquid and each type

of seal, in conditions of workpiece operation as:

precomprimation, movements relating, cycle of overpressure,

temperature cycles; following the accelerated wear

in real temp.The liquids fonctionales are compatible with the majority of the metallic

materials used in the construction of hydrostatic machines: steel, aluminum, magnesium,

copper, brass,

bronz, de argint and metal carbides synthesized.Some synthetic fluids affect layers

methaliques in zinc, cadmium and copper. liquids water based may become electrolits

between various metallic parts and can cause a strong corrosion.All liquids fonctionales

must be submitted to the acidity test, who provided the information used on their

aggressiveness chemical.

2.2.6 Other properties

Water air and the metallic particles promote the oxidation of liquids, elastomers and

metals of the hydrostatic transmissions.

The cantite of water admitted to practice in the liquids fonctionales does not exceed

100 p. p.m. in the facilities provided with open tanks the contact of the liquid with water

and condensation of water. Even if it are more complicated the watertight tanks


26/128


26

presurises pneumatic or mechanical are used if the safety represents a critical factor. It is

for ca that the Azot

replaces the air in the majorityof acumulateurs impulse tools who work at pressures

which are superior has 63 bar. These measures like the increase of the maximum

temperature allowed in a instalation and the increase of the life of the fluid used, by

decreasing at the same time

the risk of fire.For example the petroleum liquids can be used in aviation until135 0C

against 90 0C in a systhem open.

The sealed circuits with many precautions are mandatory when liquids are used for

high temperature has database silicats, which in the presence of water form of

precipitats and cristales extremely dangerous for the hydraulic circuits.The property

of liquids to keep their quality physical and chemical in the

presence of water is called "hydrolytic stability" and determines

in large the duration of storage and use.The improvement of the

resistance in relation to the oxidants is obtained using the

additives which have a large afinite

for oxygen, but does not influence the properties of the liquid that either the original

state or the state oxygen.

After the consumption of aditivs (blockers of oxidation) started to be produced of

acids) which affects the elements of the hydraulic systhem.The evaporation of the

gas and the excessive agitation of liquids in the presence of the air have as result the

appearance of foam. This increases the compressibility of liquids, promote their oxidation

and corrosion of metals. The stabilityof the foam depends on the viscosity of the liquid,

the surface tension and the factors metal pollutants. The tendency to foam and

determinedby the

measure of the volume of the foam generated by a quantity


27/128


27

constant air. The hydraulic transmissions in circuit are not affected by this

phenomen. The open systems require precautions constructive

and the aditivation liquids fonctionales with anti-foams.During operation it is difficult

to avoid the contact of the operators with the liquids fonctionales and especially the

inhalation of their vapors. Therefore it is necessary that the fluids are not toxic in certain

concentrations. Their influence on the nasal mucosa and especially on the eyes requires

the use of screens protection and ventilation especially in case of the booths to retry the

hydraulic "death squad" consists.The pressure of saturated vapor of liquids fonctionals

must be reduced to prevent the occurrence of cavitation, especially in the case of liquids

which are working at high temperatures.The specific heat and the coefficient of

conductivity thermal must be the greatest possible to avoid large temperature

gradients.It is util that the liquids fonctionals have dielectric properties ,which permits

the use of rotary related expertize, liniares and angular with links non-isolated,

simplifying the construction of electro Contollers.The color and odour using has the

identification of liquids fonctionals.The cost is an important factor in the choice of liquids

fonctionals, especially in the case of facilities industriales complex. synthetic fluids are

more expensive by reports to those mineral. liquids fluorosis are one hundred times

more expensive than petroleum liquids.

The elastic racords cauchiuc in hard or Teflon with inserts of stainless steel have a

module of elasticity reduces, between 700 and 3500 bar which is in general indicated by

the producers. The use of this type of racords is valid in the hydraulic circuits for

automatic power supply distributors and their link with

the tank. The electrohydraulic servo valves are updates of habit on the hydraulic

motors volume fractions, it is as ca that it minimizes the volume of the liquid exposed

to pressure variations and the elasticity of the racords.The presence of air in

the liquid, even in small quantities, drastically reduces the modul of elasticity of the

systhem.The modul of elasticity efectif cannot be determine exactly that by track

experimental. Theatmospheric pressure, the volume of air which is not disolue can

represent even 20%


28/128


28

of the total volumetric. Once the pressure increases, the just becasue of the air is

disolue in the liquid and no longer assigned its rigidity.When one has to do with a

hydraulic transmission which has been in rapaus for several years, a situation which

allows the air to penetrating them in the installation, the performance of the systhem

are random until the evacuation of the air by the pumps. In this conditions the start up

of the pumps is not at all silent and there is also the danger of cavitation. The main

cause for the trapped air is represented by the projection and incorrect execution of

canales complex carried out by drilling or shooting. All hydraulic transmissions must be

planned with the buchons or taps of pourjage. The major facilities are emptied before be

used.

The fonctionales liquids are in general aditivees with antifoam agents who increased

their capacity of evacuation of air without realizing of emulsions.

2.3 . Types of liquids fonctionals

2.3 .1Liquids has vegetable basedThese fluids are composed of the castor oil diluted,

for him to increase its fluidity, in a solvent with a freezing point down and moin volatile

as possible. For example the liquid brake used in our cars is 50 % -50% of the castor oil

and alcohol(diacetone).

They are compatible with the cauchiucs naturals, which support the databases

temperatures, this type of liquid are still used in domains of specific, even if they are

corrosive, volatile because of the Solent, flammable, instabiles in time and also instabiles

by report to temperature variations.

2.3.2 The liquids has mineral baseBecause of their lubricating calitees, stability

and chemical cost related

reduces these liquids are used in the hydraulic has been limiting who work in the field

of temperature -54 0C and 135 0C. concerning the hydraulic transmissions industriales or

those of aeronautics, exposed to a fire, the liquid has mineral base are usually

replaced with synthetic liquid flammable as the esters fosfats or esters silicats.


29/128


29

The range of oils is very wide, the producers offerent of liquids from each group

visquese of liquids fonctionals industrials was sold.Carasteristques groups of visquosite of

liquids fonctionales industrials was sold:

GroupCalificatif

Viscosity

has 50 0CGrades EnglerViscosity

has 50 0C

Centistokes1Extrafluides2

11

2

Very smooth 2 - 3 11 - 203Fluids

3 - 4

20 - 294Semifluides

4 - 5

29 - 37 5 Semivisqueses 5

37 The hydraulic

installations of

aeronaves frequently

use the hydraulic

liquid standard,

which can be defined

according to the

French standard AIR

3520/A: mineral oil

with point of runoff

reduced (< -60 0C

) with a point of

inflamabilite

more top of 93

0C, with a hint of

acidity reduces (< 0.1

tricresilfolsfat for

the improvement of

-MIL H 5606 in USA -AMG 10 in Russia


30/128


30

mg hidroxid

potassium/g ),

additive with 20%

enhancers of

viscosity index

(example: polimer

metacrilic) , with 0.4

0.6 per cent

quality lubricating),

with 2% antioxidant

and 100 p. p. m dye

(red). This liquid is

called in France AIR

3520/A and it has as

equivalent:

-DTD 585 in UK -H 10 in Romania It is very stable, not

toxic, compatible

with most of the

synthetic elastomers,

it has a viscosity

index

very good, but it is

inflamable.

2.3.3 Liquids non-

inflamables has basis

of water

Because of a few

deficits, as a limited

field of temperature,

viscosity

and other lubricating properties promote very reduced, corosivite, water is

used usually for the action of the tooling "warm", large consumers of liquid, such as the

hydraulic presses. The improvement of properties of water can be obtained by its mixture

with oils or poliglicols.The oil emulsions in water contains between 1 and 10% mineral oil which increases the

quality of lubricating water and limit the aggressivenesschemical. ternational emulsions have a good viscosity

index and are compatible with the elastomers and usual paints used on the tooling.

The emulsions of water in the oil

in a concentration of 50 - 60% in

providing an index of high viscosity ( 140 ) and compatibility with elastomers and paintings

currents, as even the lubricating properties remain modests, they are used usually in

hydraulic installations


31/128


31

of mining tools has the high pressures around 400 bar.

Solutions of glycols in water contains water

approximately 35 - 65% have lubricating quality good and an index of high viscosity

150, but they are incompatible with the liquids tankers, zinc, cadmium additions and

existing paints (except those viniliques). ternational solutions are used especially in the

navy. The water vapors play the rol of extinteur, but the presence of water limit much the

field of temperature. has more than 60 0Cwater if evaporise cca and ca as the quality of

the flame-retardant liquid decreases.

2.3.4 Synthetic Liquids The esters of organic acids

represent liquids of high temperature but it are not resistentes at lights. They have

the point of inflamabilitebetween 160 0C and

200 0C, but they have a low randament has temperatures databases and are

incompatible with certain elastomers. Initial they were used as synthetic lubricants for

engines

thermal has present they are used on supersonic aircraft civilian.The components

organic halogens (flourats or clorurats) are non-flammable but they have a very high price,

high density, index of visquosite reduces and bear lasted long enough the additives, it is for

ca that in this they are used fairly rar.

The silicons are liquids non-imflamables of high temperature ( can work up a 315 0C

), their index of visquosite is high but they have the lubricating properties low, they are

pushing intensity,

they are insensitive to the aditivs and they are expensive. In addition they have a

module of elasticity reduced and have a special comportament in the bearings, they are of

fluids non-newtonienes.Esters fosfatshave very good lubricating quality, viscosity index

very large (

approximately 240 ), point of inflamabilite high( 260 0C ), but they have a densityrelatively large (


32/128


32

approximately 1.08 ), are sensitive to the cisaiellement and toxic. THE instabilities in the elastomers

companion bills as the boutils 70 - 80 0C and etilenpropilenes until 1000C , restrict their

operating temperature was 100 0C. These liquids may be regarded inflamables but not also

the liquids of high temperature, are used on civil aircraft and civilian navirs, also in eliminate

many shortcomings depriving senior citizens hydraulic installation industriales exposed

to the danger of the lights (for example ,those mining). A typical example of ester

fosfat usesis the liquid SKYDROL 500 A, used on the Boeing aircraft.

The silicats (ortosilicatesters and polixiloxans) can be used between - 40 0C and 150

0C. their major disadvantage is represented by their sensibilities has air and water, in their

presence they produce precipitats and crystals especially has hot.This sensitivity

imposes severe precautions concerning the design, replisage and maintenance of syshtemes.

They are liquids of high temeperatures but they are not non-inflamables even if they have a

good level of security for the fires. In this category am part the liquid ORONITE 8515 was

used in the hydraulic installation of the passenger aircraft Concorde.The liquids

of high temperatureare necessary for aircraft and hypersonic raquetes, who have

a warming significant dynamic.

are studied in this purpose the liquid metals already tested in the primary circuits of reactors

nucleares, the mercur sodium, potassium, has been prevented from Lead and bismuth

etc. Chapter 3 The design of a hydrostatic transmission of a tooling mobile

I am speaking here of the main steps of designing a hydrostatic transmission of a

tooling mobil. The main goal is the correlation of requests practices versus the production

requests.3.1.1 Data CaractheristiquesThe field of use:

The main transmission of a tooling mobil (

motocar, auto-crane , excavator )Photo1 Excavator type SPYDER

The field of adjusting the speed of the tooling in regime stationary pipe support: +

/- ( 0.125 ... 1.0 ) vmaxThe type of machines available volumetric:With the

axial pistons , with block inclined.


33/128


33

Photo1.3.1

The block of cylinders with the failover drive of the pump Parker

Photo1.3.2

The pump F220 without carcass with the pivots of failoverThe type of the

transmission command:

1) Eh , of distance.The type of the pump motor:Diesel, equipped with rotary injection pump, with

regulator of turing universal.


34/128


34

The poid Maxime

2) of the tooling: mu( in function of the type and magnitude of the tooling )The rail maxim

3) that the tooling must fit with the minimum speed stabile:max=30 grades .


35/128


35

The speed maxim in the rail maxim: Vmax

( max) = 4.5 km/h

4) The nominal pressure of the system:Pn=320 bar

5) The speed maximof the tooling:

6) Vmax= 30km/hThe dynamic radius of the drive wheels:Rd= 0.3 m7) The carryforward of transmission of planetary gearboxes of the rims of the drive

wheels: i=6The restructuring of time maxim of Diesel engine: nd(MDmax) = 1800

rpm

3.1.2 Objectives

8) caractheristiques:The design of a hydrostatic transmission can be achievedgradual, from the beginning as the choice of a systhem complete a catalog of

specialty, a basis of data schedules , andmakeanyamendments the complete

calculation, hydraulic, thermal, organologique of all componantes, in accordance

to the following diagram:Step 1 vacationers schedules:The development of the

9) hydraulic diagram of the transmission.The sizing of the main componantes of the transmission.


36/128


36

10)The hydraulic calculation, thermal and organologique dispositive of the control ofthe main pump.The preparation of the documentation of execution of the main

pump.

The preparation of the documentation for the implementation of the dispositive

of command of the main pump.

11) Step 3 The design of the block of refrichissement and protection:The establishment of principles of hydraulic componantes.

12)The establishment of a constructive solution.13)The calculation of the pressure valves

The mathematical model.The verification of dynamic performance with digital

simulation.

The calculation of the distributor of refrechissement.The calculation of the valves

of sense.

The preparation of the documentation of execution of the block of

refrechissement and protection .

1) Concerning these steps, we studied the steps necessary for the typical phasesof industrial design.3.2

2) THE ESTABLISHMENT OF THE3) HYDRAULIC DIAGRAM OF A HYDROSTATIC TRANSMISSION

The tooling for the what the hydraulic transmission is established, it is mobil, therefore it is

necessary to use a diagram of La Conexion for the pump and the motor ( engines


37/128


37

1) hydraulic ) in a closed circuit. The racords of machines must be as short aspossible with rigid tubes or

2) hoses,3) compared to conditions specific cutscenes has the application.4) The tooling being used

on short distances

1) and with large loads, it is recommended to only Ouse not the differentialmechanical and the outilisation of 2 hydraulic motors, amplasses in the rims

of the wheels. The solution with 4 wheel drive is specific to vehicles in the

field.

2) Photo3) 2.1 forest Poisoning Category

Photo2.2 hydraulic motor with pistons radials, amplase in the rims of the

wheels.

Because of the fact that the hydraulic motors are fast it is necessary the

outilisation of reducers of rotation between the motors and the rims.

4) Because of the small space it is recommended to use the planetary gearboxeswith a speed.

5) The transmission ratio usual of these gearheads is i=6 , this solution is specificto this type of extreme load applications.

6) HAS powers of small(45-65horses) it is recommended

to use a single pump in the transmission. Concerning the major powers, it can

enter into calculation variant a pompedouble ( in the same carcass) or with 2

up to 4 pumps independent antrenees by the heat engine using a distribution

box.


38/128


38

The hydrostatic transmissions with reglaj, primar (adjustable pump) operate with

randaments acceptable in the field:Vstabil= (0.25 ..1.0 )Vmax

1) As the lower limit of the domain of adjusting the speed of the tooling,the value 0.125 * Vmax therefore the use of the setting as mixed is

imposed. adjustable pump motors and adjustable.

2) The volumetric machines being a block inclined, requires the use of apump adjustable bidirectional with 2 motors has setting unidirectional (i.e.

, frontal (TRIMOT).The optime command of the capacity

of the pump is secventielle (fig/Resolution 29.2 )During starting, the capacity


39/128


39

of the motors is mentenue constant has the value maxim and the capacity

3) of the pump increases gradually from 0 has the value maxim.4) If it is necessary the spouse later on the speed of

the utillage the pump is a positive reference has loaded maxim

5) and it gradually reduces the ability of the engine.During the braking, anymaneuvers are performed in reverse order.

6) The hydraulic control of the motor must be put in market only after therealization of the stroke of the adjusting device of the capacity

of the pump. This algorithm for adjusting the transmission

allows the realization of randaments pupils has databases speeds of the

tooling. The use of the closed circuit

7) involves the cooling of oil, its filtration,8) protection against cavitation and protection against overpressure.The

compensation of the leakage of the main circuit requires an auxiliary

pump independent of the main pump.


40/128


40

The hydraulic control requires a different pump driven by the Diesel

engines.The two pumps auxiliaries must be protejees against

overpressure.The control pressure of the capacity

of the pump and motors can be performed

with normal valves closed, normal open or drosers. It is recommended

that the solution has valve open normal double, which does not require the

use of a hydraulic distributor directional. is each valve has a direction of

movement of the tooling.The capacity

9) of the engine is slide amount just for the sense of rolling in before. Thecontrol pressure of the capacity of engines with a frontal adjustment is the

same as for the pump, but it is activated just after the arrival has the

capacity Maxime of the pump.

10)11)Fig 29.1 The structure of a hydrostatic transmission with adjustment as

mixedFig. 29.2 . The variation of capacity of machines by report has the

relative speed of the tooling.

12)Fig.29.3 The caractherisitique the torque of the Diesel engine [auto-forum.com]The diesel engine is equipped with an injection pump provided

to a regulator of turing universal. The characteristic of the moment by

report has its restructuring director-generalor reliable performer several

straight parallel with a Pant very large. It is possible to coreller exactly

the accelerator with the injection pump regulator.Usuallement, the

restructuring of the heat engine is kept constant at the value of the

corresponding time maxim for achieve the starting as soon as possible of

the poisoning category.

13)Taking into account these conditions it follows the hydrostatictransmission hydraulic schematic in Figure 29.4 with the ratings:PR - Main

Pump adjustable with axial pistonsMD - Diesel EnginePD - Double PumpP1

- section for the power supply of the systhem of commandP2 - section for


41/128


41

the power supply of the systhem of leak compensation of the main

circuitF1 - suction filter with valve of detour

14)SLP1 - valve which limits the pressure of power supply of the controldeviceSLP2 - valve which limits the pressure to leak compensationNSSDS -

normal valve open electro-hydraulicCHDERE -

hydraulic cylinder double acting and

spring return of the control device of the main pump


42/128


42

BICP - block of refrechissement,

15)compensation and protection against overpressure of the main circuit

SS1 .SS4 - valves of meaning

SLP3, SLP4 - valves which limits the pressure in the main circuit

DHCH 3/3 - hydraulic distributor hydraulic operated with three votes and three positions

SLIP - valve that limits the lower pressure of compensation


43/128


43

RU - Cooling Oil

MHVRF - hydraulic motor by volume with frontal adjustment

RT - Swing Reducer planetary

CHDED - hydraulic cylinder has double effect, differential

Fig. 29.4 . The transmission hydraulic schematic

In this diagram you can see the schematic mechanical-hydraulic transmission from a heavy

poisoning category. In the left part of the drawing was the controls and in the right part we

observed the transmission.

In the center there is the diesel engine MD which is linked directly to a main pump PR for the

transmission which allimente two hydraulic motors in paralel on the axis of the

vehicle, and (two pumps are usedon)has a pump P1 of command and has a pump P2 of

refrechissement of oil. The pumps P1 and P2 aspire the oil from the tank through a filter F1

which is also provided with an anti-cavitation valve, in cases where the filter is clogged,

bypass. The pump P2 refrechie the oil of any the installantion, it is necessary to remove the

oil which started to heat up during operation. The control pump P1 is provided with a

pressure limiting valve. Once the fluid output of the pump P1 it between in a circuit with

two

valves normal open has for the market-rear and B to go to the front. The two valves normal

open

are linked to the control device of the main pump

CHDERE. The two

valves to normal pressure

are provided with The springs of position which ensures their initial position after it

executes a command front - rear. If it chooses the reverse of the poisoning category the

distributor has changed position the hydraulic cylinder control CHDERE moves to ca right, in

antrenant the main pump


44/128


44

of the transmission by a mechanism. Same thing to go forward, the distributor B changes

position influence the position of the CHDERE , the former has his turn influence the main

pump to the transmission.

Transmission side, it is a question of two circuits, circuit has low pressure, the circuit of

refrechissement and the high pressure circuit of the transmission circuit. After the main

pump on as the valves of meaning SS1 and SS2 which ensures the safety of two circuits of

the transmission of high and low pressure, the valves SLP represent the valves of limitation

of the pressure in the block of refrechissement of compensation and protection against

overpressure circuit

main.

An important part of the transmission is the distributor in command pressure which ensures

the drenage of oil from the low pressure circuit, the former is linked to the oil tank cooled by

a valve that limits


45/128


45

the upper pressure.

Regarding the last part of the schema on votes the


46/128


46

two engines with volumetric adjustment MHVRF frontal with the CHDED which represents

in fact the distribuiteurs related to hydraulic pistons has dual differential effect. The

phenomenon is the following. At the time of acceleration, the part command using the

normal valve open B command the main pump PR ( its meaning ) and the latter allimente the

hydraulic motors related to wheels. If it remains with the throttle control still , the pressure

will increase in the control block and the fluid near distributor B va allimenter directly

distributor P which will actioner on cylinder CHDED who is bound by a systhem lever of the

hydrostatic motor, the CHDED changes the angle of basculation of engines, and as ca the

vehicle gained speed.3.3 SIZING OF THE MAIN COMPONANTES OF THE

TRANSMISSION3.3.1 Sizing of hydraulic motorsThe hydraulic motors must ensure the

propulsion of the tooling in rail maxim. Fig 29.5 scheme for calculation of the force.Fig 29.6

scheme for calculation of the time of tractionIn this case the law enforcement agencies

caractheristiques who intervene in the dynamics of the tooling are:Fg

- the force of weightFt - the traction forceTFF

- the componante tangential to the force of weight of the tooling supportThe time required

of a wheel is: Mr = Ft

rd / 2 (fig. 29.6 ).If we do ignore the load resistanceto the aerodynamics and the load

resistanceto the driving when the traction force necessary in this case will be:

(29.1 ) The two hydraulic motors desvoltent a tractive force:

(29.2 )


47/128


47

The time provided not a hydraulic motor is:

(29.3 )

Or:

(29.4 )Represents the theoretical time maxim given by the engine under the pressure

drop Maxime, and

represents the mechanical randament coresponding has this de Rgim of operation. It

admits .

By introducing in the relations: (29.3 ) and (29.4 ) in the relationship (29.2 ) one obtains:

(29.5 )

Relations (29.1 ) and (29.5 ) it follows: (29.6 )The relationship of dimmensionement

hydraulic motors is: (The calculation of the capacity Maxime necessary) (29.7)

In the appendix 1 we chose the engines that corresponds to the condition of capacity

Maxime and pressure drop maxim.

maxmaxgmaxt sinmgsinFF Observation:


48/128


48

in the catalogs there are shown three caractheristiques pressures for the volumetric engines:

d

maxmmaxt

r

iM2F The pressure maxim of operation

The nominal pressure

maxmmmaxtmmaxm PMM The pressure maxim of intermittent

operation

The pressure Maxime continues corresponds usually with the randament total

2

PVM maxmaxmmaxtm

Maxime () maxmmP of the car and to a duration of operation at least equal with the life of

the more perisable part of the installation. The ideal solution represents a life unique for all

componantes important: engine, hydraulic transmission, steering, suspension, technological

instalation. mm Pmax ,0 95For the picture of the calculations we consider a motocar

factory having mass m= 2200kg

The force required to mount a Pant:

maxmm

d

maxmaxmmaxt P

2r

PVi2F

By report at the time of the wheel:

maxmmaxmm

d

maxmax VP

r

iPsinmg

The capacity necessary to the engine:

Now having this value, look in the appendix the hydraulic motor which we agrees:

maxmaxmax

maxdnecesarmaxm

Ppi

sinmgrV

Appendix 1

Table nr. 2

THE CHARACTERISTICS OF ENGINES WITH FRONT ADJUSTING TIP F6Tip U.P. HAS


49/128


49

a) F616b) F620c) F625

F632Capacity (cm3/rot] Vgmax ,=250 maxt

Vgmin

,

=70

31.1

()

9

63

18.2

125

36

72.1 The

pressure ofduration pd

[bar] 200 The

nominalpressure

pn[bar]


50/128


50

320

The pressure

Maxime pmax[bar]400The flow rate at

the nominal speed of work has empty

[l/min]45

91.4

181.5

242

The nominal

flow rate p=

320bar [l/min]

42.5

87.5

174

232

The time for max=250 Theoretical[Nm] Nominal 158

3176361272 140

255 569 1147 The

nominal

rotation

speed

(rot/min]

1450

970 The

minimum

speed

(rot/min]

200 The speed

Maxime

[rot/min]

=250

=704000

3400 2600 2000 5500

4300 3500 2800 I chose the

engine F

620

who has a: and a 3.4

THE SIZING OF THE MAIN PUMP

The determination of the maximum load

results from the condition of insurance of

the maximum speed imposed has the

tooling. (29.10 )In this relationship n

r max represents the maximum

restructuring of wheels on here result:

(29.11 ) The necessary

flow of

hydraulic

motors in this

de Rgim is:

(29.12 ) Or

vm(nmmax) represents

the

volumetric

randament

engines has

the

restructuri

ng and

maximum

capacity

minimal. It

admits

vm(nmmax)= 0.97 .The pump supplied the maximum flow :


51/128


51

(29.13 )Or nd(MDmax) represents the restructuring the maximum time of the

Diesel engine.It is assumed that the heat engine work always has the restructuring the

maximum time, to use the full time starting available. This reglaj is specific to the

utilages intense mobile used. ( for example trucks portuares )

v r r n r n id d r d mmax max max max/ 2 2 Of relations (29.12 ) and (29.13 ) it

calculates the required maximum capacity of the pump:

(29.14 )This is the relationship of sizing of the main pump of the transmission. Usual vp(Qp max) = 0.97 has a pressure of

approximately 100 bar, corresponding to usual has the maximum load of the pump, capacity minims of engines and

n v i

rm

d

maxmax

2 the driving has maximum speed

on a horizontal path.

In my case, concerning my motocar it follows:

Q n V nm m m vm mmax max min max/2 THE PUMP:

The speed maxim: The rotations per minute of hydraulic motor:The necessary flow of

engines:The flow rate from the pump: 29.14Once known Vp max

i chose a pump of the appendix:Appendix 2

Q n M V Qp D D p vp pmax max max max Table nr. 2

THE CHARACTERISTICS OF UNITES WITH AXIAL PISTONSTAYPE F6

Type U.P. A.F212

F216

maxmaxmaxminmax

max

2

pvpmvmDD

mm

p QnMn

Vn

V F220


52/128


52

F225F232F240

F250

250

250

250

250

250

( ) ( ) ( )

250250


53/128


53

Capacity (cm3/rot]

14

31.1

63 125 250 468 950 The

nominal

pressure

of work

[bar]

210 210

210 210 210 210 210 The

nominal

pressure

[bar]

320 320

320 320 320 320 320 The flow

rate atthe

nominal

speed of

work has

empty

[l/min]

20.3 45

91 181 242 453 693 The

nominal

flow rate

p=320 bar

[l/min]

18.8 42.5

87.5 174.6 232.5 438 670 The time

for

max=250

[Nm]

79 176 356 706 1413 2646 5370 1450

1450 1450 1450 970 970 730 The

speed of

rotation

circuit

closed

(engine)

Maxime

[rot/min]

open

circuit

(pump)

300030003

000

2550 3000 2200 2600 1800 2000 1280

2000 1200 1200 950 I chose

the pump

F220 with

a capacity

of 63

cm3/rot

and with

a flow

rate at

the

nominal

restructur

ing work

free of

Qp=91

m3/min

3.5 The

justificati

on of

solutions

of

principle

and

construct

ive

solutions

adopted

3.5.1 The

justificati

on of

solutions

of

principle

and

construct

ive

adopted

for themain

pump


54/128


54

In the

framework

of a project

of pump

with axial

pistonswith block

enclinee

FIG 29.7

The first

problem

that must

be solved is

of nature

kinematicsand affects

the

modality of

entrainnem

ent block of

cylinders

toward the

shaft.

At present

there are

threeknown

modalities

of

entrainnem

ent:

A) by

cardan

shaft

B) by

the

contactside of

the

pistons

and

connecti

ng rods

C) by a

bevel gear

The first

solution is

specific to

transmissions of

high

reliability,

because

use of the

cardan

shaft

exclude

the

possibility

of ruptureof rods by

fatigue

has the

twist,

specific to

this

solution b)

.

The

cardan

shaft is

actuated

by acouple

small, or

predomin

ant is

compona

nte

inertial

which is

manifest

ed during

the

transitional

regimes.

Same as

ca the

shaft

complicat

es the

construction and

increases

the radial

template

of the

machine.

Mentenir

contact

between

the block

ofcylinders

and the

distributi

on plate

imposed

The use of a resort, amplasee has the outside of the cover of the racords. contact between the resort

and the block of cylinders need a supplementary rulment axial.

The shaft cardanique must be axial is crooked or is positioned incorrectly by a

resort which

is support on the block of cylinders and on one of these ends. On the other side the

shaft cardanique se support on the block of cylinders using a spherical joint.

This solutionalso has the advantage of setting from the outside of the contact

pressure between the block of the cylinders and the distribution plate, allowing a

control sever leaks. Also the torque piston-biele become more lightweight and allows

the increase of turations.because of all these advantages the antrennement of the

block of cylinders by shaft cardanique is rependue of aeronautics in the field of


55/128


55

mobile applications Industriales, especially in the reversible variant used as the

engine for large loads inertiales. The disadvantage of this solution is represented by

the high cost.

The second solution has the smallest radial template for a given capacity. By the use

of the spherical distributor is eliminated the need for guidance of the block cylinders

by a shaft supported on the disc of entrainnement pistons and on the distribution

plate. As same it should use a cylindrical abre- spherical which has the rol of pressing

the distribution plate on the blocked of cylinders, against the force bearing break

complex formed by the two parts.

The continued caution which must be considered when the outilisation of such a

machine as pump is prescription of a pairing more elastic for the entrainnement of

the machine to force ( job ). Now we used in this purpose of couplings "Periflex"

which present a spring element which is still in progress of improvement concerning

the rigidity torsionale.

The third solution requires a high precission of execution and mounting of the conical

engranage. adjustment of the clearance of the engranage need a carcass divided

realize two semicarcasses. Intre them it is provided for a spacer with a largeut

established when mounting.

a) The solution is adequate especially for the reversible machines used as enginesfor large workloads inertiales very large. Being compact, it is also used in the

transmissions has large template. An example caractheristique is represented bythe entrainnement pumps portable sousmersibles for depletions.

It is adopted for the main pump of the transmission variant b) with mounting precautions

and utilization. It is recommended to avoid shocks during the transitional reigmes.2. The first

option presented must be supplemented with observations of nature and kinematic

hydraulic. To avoid a permanent consumption of energy by the use of a distributor

directional between the pump and engines, we adopted the solution of adjustable pump in

the 2 directions (= -250 ... 0 ... + 250


56/128


56

). As ca we exclude for the pump, the solution with front adjustment, which has a template

smaller.The pumps has frontal adjustment reduissent much the weight of the groups of

pumping, but being unidirectional, in the case of transmissions which necessities the

reversal of the direction of hydraulic motors must be accompanied by distribuiteurs

directionales.

Fig. 29.7 . Section caractherisitique by the main pump.

It therefore uses the classic solution for directional pump which is caractherise by the

emplassement block of cylinders in a carcase flipper performed by the following

componantes:Cylindrical Carcase scheduled with the racords L-Shaped

Timing Gear Cover scheduled with the fittings in U shapeCoaxial shafts which

contains has the inside of the canales of distribution.

A shaft of basculation is usual outstanding superrieur which is at the top, provided with

grooves our the actionnemet of the carcass baculante by the dispositive of adjustment.3.

The rocking carcase must be directed and sustained. It is possible to Ouse 2 bearings radials-

axials with tapered roles which allow

b) the adjustment of the axial position of the carcass of a way that the center ofspherical joint between the disc of entrainnement and the Faultfinding chart

guidance of the block of the cylinders is located at the intersection of the axis of

the blocked the cylinders with the axis of the shaft. This solution complicates the

structure of the rotary racord between the shaft of basculation and the carcass

fixed to the machine. By consequence we adopted the solution with the guidance

of radials bearings for the pivots of basculation also constitutes and the aneaux

interieres, supporting at the same time the carcass with a tilt table elementary

level between the

pivot


57/128


57

c) of basculation and inferior and the cover of the racord coresponding. The wearpart is a eye distantier hard, level and smooth. The width of the the is optional

connections, satisfying the condition fundamental kinematics for the adjustable

machines.

5. For that one has a small template of the bearings we adopted the solution with 3

bearings: 2 bearings radial-axials with marbles in tandem and a radial bearing with cylindrical

roles.

6.

The use of a mechanical seal expensive between the shaft and carcass can be avoided

if the fittings of drenage of three machines of the transmission are directly connected to the

tank, do not pass through the heat exchanger and by the return filter. In this case you can

use a joystick to rotate single or double.7.

Tenand account of the fact that it can be realize as part unit of the corp of the upper coupler

and the corp of the dispositive of adjustment, we adopted for the hydraulic cylinder of the

the the solution which are fitted symmetrically ( 2 hydraulic cylinders with a simple effect

realizes between two covers and a piston type plungeur )

In the interior of the cylinder there are two stes each has two resorts precompressed.

The additional comprimation of those - below during the adjustment is provided using a rod

central which has an axial position and it is adjustable from the outside.


58/128


58

The utilization of this solution allows the replacement of the carcass swinging in the neuter position with a great

precission with an interval of time adjustable using the precomprimation resorts. In the same time the

carachteristique of command is affected, because the setting of the capacitee is started only after a pressure of

a few bars.

In ansemble, it follows a carachteristique of liniare adjustment with a prag between 5 and 10

bars by meaning, compatible with the minimum pressure furnisee by the valves normal-

open mechanical control or using the electromagnets.

- 3.5.2 The justification of the solutin-- of principle and constructive


59/128


59

adopted for the HYDRAULIC MOTORSBecause of the opportunity to change the

direction of rotation of the shafts of the motors by the change of the direction of

movement of the liquid in the pump, we can use motors with frontal adjustment

scheduled with a dispositive of hydraulic control, which has the control pressure

identical with the control pressure of the ability of the pump to the market before

the tooling.The sousansemble of entrenage engine differs from sousansemble of

entrenage of the pump because it is necessary, the guidance of the block of cylinders

during the setting has the assistance of the distribution plate.

The resort which mentien the contact between the block of the cylinders and the

distribution plate is amplasee in a collar of guide shaft and the block of cylinders.

The block of the cylinders and the guide shaft turning synchronous, being solodarises

by a pen of small dimmensions.

The capacity of engines with enclinee block may be constant or variable, the usual

interval of adjustment being between 1:1 and 1:4 . Concerning the variants the

adjustable block of cylinders is amplasee in a carcase or rocking it is guided by a shaft

supported by the flange of entr

Hydrostatic Transmissions for Heavy Autovehicules

Documents

Transcript of Hydrostatic Transmissions for Heavy Autovehicules