EP0937914B1transmission Puissances Transmission

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Note: Within nine months from the publication of the mention of the grant of the European patent, any person may givenotice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in

a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.99(1) European Patent Convention).

Printed by Jouve, 75001 PARIS (FR)

Europisches Patentamt

European Patent Office

Office europen des brevets

(19)

EP

0937914B1

*EP000937914B1*(11) EP 0 937 914 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mentionof the grant of the patent:01.12.2004 Bulletin 2004/49

(21) Application number: 99200445.7

(22) Date of filing: 15.02.1999

(51) Int Cl.7: F16H 61/00

(54) Continuously variable transmission

Stufenloses Getriebe

Transmission variation continue

(84) Designated Contracting States:

AT BE CH DE DK ES FI FR GB IE IT LI LU MC NLPT SE

(30) Priority: 23.02.1998 EP 98200558

(43) Date of publication of application:25.08.1999 Bulletin 1999/34

(73) Proprietor: Van Doornes Transmissie B.V.5000 AM Tilburg (NL)

(72) Inventors: Ketelaars, Johannes Antonius Adrianus

5382 JB Vinkel (NL)

Pelders, Hendrikus Adrianus Arnoldus

Wilhelmina5391 BT Nuland (NL)

Brandsma, Arjen

5045 WN Tilburg (NL)

Van Heeswijk, Adrianus Albertus Antonie

5011 VH Tilburg (NL)

Van Lith, Johannes Hendrikus

5258 PL Berlicum (NL)

(56) References cited:EP-A- 0 451 887 WO-A-95/27159

DE-A- 4 301 591 DE-A- 19 612 870

US-A- 4 107 776 US-A- 5 667 448


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Description

[0001] Thepresent inventionrelates to a continuouslyvariable transmission as described in the preamble ofClaim 1.[0002] A transmission of this nature is known, for ex-ample from European Patent Publication EP-A-

0,451,887. In this known transmission, the transmissionof torque in accordance with the preamble of Claim 1 isrealized by means of hydraulic pressure, which is ap-plied via the driven or secondary pulley, with the aid ofa so-called "master-slave" control mechanism. The"master-slave" control mechanism is based on the factthat the pinching force applied via a pulley, owing to thewedge-like contact of the endless element or the belt ina pulley, causes reaction forces which, as a result of dis-placementof thebelt, result in a corresponding pinchingforce in the bearing of the belt in the other pulley.[0003] Continuously variable transmissions of thepresent type have the current drawback that the trans-

mission is susceptible to slip if the radius over which thetransmission element is in contact with a pulley is small.Therefore, similar transmissions are known in which thepinching force is constantly applied alternately, as afunction of the transmission ratio during operation, tothat pulley in which the radius of contact with the belt issmaller. This type of control has the characteristic fea-ture that the hydraulics have to be very accurately con-trolled and that the alternations during operation mayoccur very frequently, depending on the conditions intraffic. Applying pinching force using the control systemof the transmissionto which theinvention relates, name-ly exclusively, at least in principle, from the driven, alter-

natively denoted, secondary pulley, avoids such alter-nations and, inter alia, has the advantages that themeans for applying the pinching force, in this case thehydraulics and the control mechanism for the hydrau-lics, can be kept relatively simple. In the standard caseof applying pinching force by means of hydraulic pres-sure, pump pressure applied can be applied to the sec-ondary pulley without the intervention of hydraulic con-trol elements, and it is possible for the control mecha-nism to comprise relatively simple hydraulic control el-ements which have been optimized for their particularfunction.[0004] In the known transmission, an electronic con-

trolsystem is used to determinethe pinching force whichis to be applied to thesecondary pulleyin order to realizea slip-free transmission of a torque to be transmitted, inthe primary pulley as well. In the known transmission,the magnitude of the torque to be transmitted is deter-mined, inter alia, on the basis of the throttle position de-tected and the vehicle speed detected. The pinchingforce determined in this way is kept as low as possible,in order to prevent energylosses while neverthelesstak-ing into account a safety margin.[0005] A further document, the published GermanPatent Application DE-A-19 612 870, discloses the fea-

tures of the preamble of claim 1.[0006] Tests and practical experienceon commercial-ly available vehicles have shown that such a control fora variable speed gearbox functions as expected andcorrectly under rotating conditions.Nevertheless, unde-sirable tracesof apparently short-lived slip maybe foundon contact surfaces of the drive pulley and the belt in

the known transmission. The present invention is basedon the problem of establishing a cause for such tracesof slip. The invention aims to arrive at a control systemadapted so as to take into account the cause estab-lished, while maintaining the energy-efficient nature ofthe present control mechanism. According to the inven-tion, this object is achieved by means of the measureaccording to the characterizing portion of Claim 1.[0007] According to the insight on which the inventionis based, the abovementioned traces are at least par-tially caused when the transmission is started up, andthebelt is inan untensionedstate when thetransmissionis first set into operational state. Measurements forming

the basis of the invention have demonstrated that in thisstatepinching force applied to the belt by the secondarypulley does not result in corresponding reaction forcesin the primary pulley, so that the pinching force prevail-ing in the latter is insufficient to prevent slip. A furtherproblem underlying the invention then also consists ofachieving sufficient pinching force on the drive pulley inthe state of the transmission described above. Thepresent inventionthenalso consists in recognizing in thecontrol system of the transmission thestate in which thetransmission is started up from a standstill and whichprecedes the normal operation of the transmission.[0008] A particular advantage of a first refinement of

the design according to the invention is that the belt istensioned even when at a standstill only on the basis ofthe torque to be transmitted. This is important becauseapplying pinching force entails consumption of powerand therefore a reduction in the efficiency of the trans-mission. The design according to the present inventionensures that in the absence of torque to be transmittedwhen at a standstill, tensile force is not applied unnec-essarily. Another advantage of the present invention isthat the control system which is already used in thetransmission can largely be implemented while adher-ing to the rules employed and in principle without theneed to provide additional hardware.

[0009] In the solution to the problem underlying theinvention, the tensioned state of the belt when at astandstill is achieved by applying pinching force via theprimary pulley. Outwards, i.e. radial movement of thatpart of the belt which is in the primary pulley has beenfound to be achievable, when at a standstill, even byapplying a very low pinching force, in relative terms, tothe primary pulley. Nevertheless, in this embodimenttoo, pinching force has to be applied to the secondaryside in order to prevent shifting of the transmission, al-ternatively denoted, a change in the transmission ratio.In this particular solution, the pinching force applied to

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thedrivenpulley mayadvantageouslybe lower than thatwhich is applied by thecontrol systemin thesubsequentrotating conditions, via the driven pulley, in order totransmit a corresponding torque, a situation which ismade possible by the fact that in this case the frictionforce between belt and secondary pulley works to theadvantage of the intended effect.

[0010] In a preferred embodiment of the invention, thetransmission is not switched over to a pinching forcemagnitude associated with rotating conditions before atleast onerevolutionof the drivenpulleyhas taken place.Although it is desirable for this changeover to a lowerpinching force to take place as quickly as possible, forconsiderations of efficiency, this measure forms a safetymeasure which has been obtained on the basis of tests.This is because it has been found that the reaction forc-es which are desired in the primary pulley after a revo-lution of this nature correspond to the pinching force ap-plied in the secondary pulley when the pulley is set inmotion from the tensioned state of the belt. In the mean-

time, the reaction force in the primary pulley builds upabruptly from zero to virtually100% of thepinching forceto be expected from the application of pinching force onthe secondary pulley.[0011] A third particular refinement of the solution ofthe problem underlying the invention also consists inproviding the transmission with a so-called DNR set inorder to enable thedirection of travel to be reversed, thesaid DNR set being provided, for this purpose, with acoupling and being coupled to the secondary shaft, andthe transmission being controlled in such a manner thatslippage of this coupling takes place while the transmis-sion is at a standstill and during at least a number of

initial revolutions of the primary pulley.[0012] In a further preferred embodiment, the pinch-ing force is controlled in accordance with the arrange-ment for stationary pulleys for a few revolutions, so thata relatively inexpensive speed sensor can be used in-stead of, for example, an encoder for detecting rotation.Another preferred embodimentrelates to a transmissionwith rotation-dependent contact elements which indi-cate the presence or absence of a partial or of at leasta full rotation.[0013] Furthermore, as particularsolutions, the inven-tion comprises a transmission in which, during thatphase of revolution of the primary pulley which compris-

es the initial standstill, the torque transmittedby a drive-offclutchaccommodated in theprimary shaft is substan-tially lower than during the immediately following phase.To this end, delay means may be arranged in the clutch.These means are preferably electronically controlled.[0014] According to yetanother particular solution ac-cording to the invention, the transmission is providedwith antislip detection and control means and also withsignalling means in order to be able to signal the controlsystem of a motor to which the transmission is or will becoupled. An antislip detection and control system of thisnature is known fromthe international patentpublication

WO 95/27159. This system may be insufficiently effec-tive if the source of the pinching force, in this case thepump 21 of the transmission, for economic reasons hasa limited capacity up to the maximum pressure which isto be deliveredduring operation. In such a case, accord-ing to the invention, the design of a drive train is advan-tageously characterized in that in the initial phase the

maximum torque to be transmitted is adapted to themaximum torque which can be transmitted on the basisof the available pinching force or pump pressure. In or-der to be able to realize this solution, the antislip systemaccording to the invention is provided with the above-mentioned signalling means.[0015] According to yet another particular solution,according to the inventiona continuouslyvariable trans-mission of the present type is accommodated in or issuitable for being accommodated in a drive train com-prising a drive unit, such as an internal combustion en-gine, and this is controlled in such a manner that themaximum torque to be transmitted in the abovemen-

tioned initial phase is limited to a maximum until the ve-hicle or the primary pulley has reached a defined speed.[0016] The invention furthermore comprises all pos-sible combinations of the particular solutions described.According to the invention,a particularcombination con-sists in increasing the secondary pinching force duringtheinitial phase andinterveningwith theengine orclutchtakes place only when, on the basis of the torque to betransmitted as detected by the control system, the avail-able secondary pinching force the case in so-called stallconditions under which the engine power is increasedto a maximum while the vehicle brake is being actuated,approaches a maximum value given by thetransmission

system.[0017] The invention is explainedin more detail belowwith reference to a drawing, in which:

Figure 1 diagrammatically depicts an electronicallycontrolled continuously variable transmission;Figure 2 diagrammatically depicts the way in whicha push belt is in contact with the primary pulleywhilethe transmission is being started up in the unten-sioned state of the belt;Figure 3 diagrammatically depicts, in accordancewith Figure 2, the desired contact which occurs un-der rotating conditions.

[0018] Figure 1 showsan embodiment of an electron-ically controlledcontinuously variable transmission. Thetransmission 1 comprises a primary shaft, alternativelydenoted drive shaft 2, on which a primary pulley, in theform of conical discs or primary pulley halves 3 and 4,is arranged, of which the pulley half 3 is fixed to the pri-mary shaft 2 and the primary pulley half 4 can be dis-placedalong the shaft 2. In the embodimentof the trans-mission 1 illustrated, the axially displaceable pulley 4can be displaced by exerting a hydraulic pressure in acylinder chamber 5. The pressure in the cylinder cham-

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ber 5 is controlled by primary electronic control means6 which are connected to the cylinder chamber 5 andthe function of which is to set the radius of revolution ofa drive belt 7 arranged between the pulley halves 3 and4 by adjusting the pressure in the cylinder chamber 5.The drive belt 7 is of the so-called push belt type, i.e. isprovided with transverse elements which surround one

or more sets of metal rings, via which push belt a push-ing force can be transmitted between the two pulleys.[0019] The transmission 1 furthermore comprises asecondary or driven shaft 8, on which a pulley is ar-ranged which has secondary pulley halves 9 and 10, ofwhich the pulley half 9 is fixed to the shaft 8. The pulleyhalf 10 which can be displaced axially on the shaft isdisplaced by exerting pressure in a cylinder chamber 11which is connected to secondary electronic controlmeans 12.[0020] The control means 6 and 12, respectively, areconnected, by means of lines 13,14, respectively, to thecylinder chambers 5 and 11, respectively. The tension

in the drive belt 7, which is also positioned between thesecondary pulley halves 9 and 10, is maintained by ex-erting a suitable pressure in the cylinder chamber 11 bymeans of the secondary electronic control means 12.[0021] With the aid of the control means 6 and 12, re-spectively, the transmission ratio and the tensile forcein the drive belt 7 are respectively affected hydraulically.For this purpose, the control means 6 and 12 containprimary and secondary displacement means which areto be explained in more detail. These displacementmeans do not necessarily have to be designed in orderto affect the transmission ratio and the tensile force hy-draulically, butratherit is conceivable for thesedisplace-

ment means to be of electronic nature and to containsuitable electromechanical transducers, in order, by dis-placing thepulleyhalves4 and10, respectively, to makeit possible to affect the transmission ratio and the tensileforce in the drive belt 7, respectively. The primary andsecondary displacementmeans, which are thus of elec-tromechanical design, may, for example, contain awormwheel which can be set in rotation and with whichthe pulley halves 4 and 10 are displaced axially. The hy-draulic design of the primary and secondary displace-ment means will be explained in more detail in the fol-lowing text.[0022] The transmission 1 is intended to be coupled

to the primary shaft 2 of a driving engine 15 which isoperated with the aid of a thrott le 16 which is coupled toan accelerator pedal (not shown) and which, in a man-ner knownper se, receives an electronic signal from theprimary electronic control means 6.[0023] The transmission1 furthermore comprises fur-ther electronic control means 17 which are connectedto the secondary electronic control means 12 via termi-nal (Tpr). Via a command input (C), the output signalfrom the further control means 17 is fed to couplingmeans 18 which are coupled to the secondary shaft 8.Via a shaft 19, part of which is illustrated, the coupling

means 18 transmit the torque, which is ultimately con-trolled by the transmission, to the wheels (not shown) ofa vehicle.Thecouplingor lockupmeans18 areswitchedon and off by means of a signal to the command input(C) which, by means of the further electronic controlmeans 17, is derived from a signal on terminal (Tpr),which in turn can be taken from the control means 12.

[0024] In the embodiment illustrated, the coupling orlockup means 18 (for example a torque converter) arearranged downstream of the secondary pulley in thedrive direction. The means 18 may without any problembe arranged in a different configuration or at a differentposition in the transmission, for example on the primaryshaft. In the context of the present invention, the latterarrangement will be used as thestarting point. In an em-bodiment which is not illustrated, the primary shaft is in-terrupted by a torque converter which is known per seand the secondary shaft is interrupted by a so-calledDNR set, which is likewise known per se, allowing thedirection of travel to be reversed. To this end, a DNR set

of this nature is provided with couplings.[0025] In Figure 1, the following are also given as in-put signals for the electronic control means:

= position of the accelerator pedal of the vehiclein which the transmission is to be accommo-dated;

= position of the throttle;Np = rotational speed of the primary shaft 2;Ns = rotational speed of the secondary shaft 8, cor-

responding to the vehicle speed;Nm = rotational speed of the engine.

The electronic means may all be accommodated in aso-called electronic control unit, such as a microcom-puter, from which the various electromechanical controlmeans present, such as hydraulic slide valves, can beoperated. With regard to the other components, and inso far as nothing different is shown in the preceding text,a possible design of the present invention correspondsto the design shown in Patent Publication NL-A-9000860, which corresponds to EP-A-0,451,887.[0026] Figure 2 illustrates the way in which the belt 7is in contact in the desired tensioned state in the primarypulleyP and inthe secondary pulleyS in the low positionof the transmission. In this position, the belt bears

against the primary pulley with the smallest possible ra-dius and against the secondary pulley S with the largestpossible radius. Consequently, the surface area availa-ble on the primary side for the transfer from the relevantpulley to the belt 7, composed of at least one annularcord 25 anda numberof links 24,is considerablysmallerthan that on the secondary side.[0027] Figure 3 diagrammatically illustrates the con-trol system of the transmission to which the present in-vention relates and, together with the assembly com-prising pulleys P, S andbelt 7, forms a so-calledvariator.Figure3 depictsan oil pump 21 which taps transmission

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oil from the reservoir 20 and, via line 13, feeds this oilinexpensively, i.e. without the intervention of any hy-draulic valve, to the hydraulic cylinder of the secondarypulley P. The pressure prevailing in the secondary cyl-inder 11 is determined by the position of a control valve22. This pressure results, determined by the surface ar-ea of the primary cylinder, in a pinching force Fs on the

belt, which is depicted as a balance bar 7'. Oil removedthrough control valve 22 returns to the reservoir 20 afterit has been diverted via a cooling and lubrication circuit.[0028] Furthermore, as in the position illustrated, thepump may be connected to the primary cylinder 5 viathe three-way valve 23. In a second position, the con-nection between pump and primary cylinder 5 is closed.The third position of valve 23 makes it possible for oil toflow back to the reservoir. The valve 23 is moved intoone of the three positions depending on whether it isdesired to increase, reduce or maintain the pressure inthe primary valve. The explanation given is eminentlysuitable for the present master-slave control system, in

which only the secondary pulley acts as a "master".[0029] The factor K represents a transmission prop-ertywhich is dependenton thegeometry of an assemblycomprising belt and pulley and varies with the ratio andthe torque to be transmitted. The factor K is a measureof the ratio between the applied pinching forces Fp andFs, the belt remaining in an equilibrium state, i.e. a statein which the belt does not change or in which there isno ratio adjustment. In the present transmission, themagnitude of the pinching force Fp and Fs is decisivefor the torque which can be transmitted, while the ratiobetween thetwo pinching forces is decisive for thetrans-mission ratio.

[0030] In the known transmissions of the type de-scribedabove, slip occursin some cases.Nevertheless,thecontrol systemfor applying pinching force is adaptedto the instantaneous torque to be transmitted. This hastheadvantage that energyloss causedby unnecessarilyhard pinching is avoided. Therefore, preventing slip byincreasing the pinching force forms an unattractive so-lution, all the more so since the control system of thetransmission generally functions well.[0031] According to the invention, the abovemen-tioned slip takes place primarily when torque is appliedfrom the standstill position of the variator, for exampleas a result of a coupling 18 arranged between engine

15 and input transmission shaft 2 closing. In the newcontrol system, a distinction is also made between astrategy which is suitable for the state in which the pul-leys are at a standstill or virtually at a standstill and theusual strategy which during operation follows the newstrategy mentioned first and which is active for compar-atively only a short period and at very low vehiclespeeds, and which even in city traffic and in traffic jamsis passed throughonly when driving off froma standstill.Owingto the fact that inthisphase the clutch isgenerallystill open or has not yet moved into the"lockup"position,any effects remain virtually unnoticed by the driver.

Therefore, the solution according to the present inven-tion retains the favourable characteristics of the currentmaster-slave control system and does not necessarilylead to a complicated lay-out of the transmission or to acomplicated control system. In the particular solution inwhich, at a standstill, hydraulic pressure on the primarypulley is adjusted, it is possible, for example from the

electronics present, for the electro-hydraulic slide valve23 to be operated fora brief time. The required level andtime of opening and the adjustment of the pressure inthe secondary pulley by actuating valve 22 can be pre-determined for each design of transmission.[0032] The present invention is not limited to the em-bodiments which have been described above, but alsorelates to all the details in the figures and the contentsof the claims which follow.

Claims

1. Continuously variable transmission (1) providedwith a drive pulley (P) and a driven pulley (S), eachhaving at least one axially displaceable disc (4, 10)for being capable to pinch an endless transmissionelement or belt (7) between the discs (3, 4; 9, 10)of a pulley (P; S), arranged so as to transmit torquebetween the pulleys (P, S), the transmission (1) be-ing controlled by a control method at least duringnormal operation at full movement of the pulleys (P,S) such that the pinching force of the drive pulley(P) is dependent on the pinching force applied tothe belt (7) via the driven pulley (S), which latterpinching force is determined, at least in part, as a

function of a torque that is to be transmitted, whilethe pressure in thecylinder chamber (5) of the drivepulley (P) is controlled by means of a hydraulicvalve (23) to set a transmission ratio, the controlmethod being set up to recognise the state in whichthe transmission (1) is started up from a stand still,characterised in that, the transmission (1) isadapted in such a manner that while the pulleys (P,S) are at a standstill and prior to the abovemen-tioned method of control at full movement, a torqueto be transmitted is transmitted with pinching forceapplied to the belt (7) by the drive pulley (P) by ap-plying pressure in the cylinder chamber (5) of the

drive pulley (P) through the activation of the saidhydraulic valve (23).

2. Transmission (1) according to Claim 1, character-ized in that, the pinching force of the drive pulley(P)corresponds to the pinching force required in or-der to transfer the torque which is to be transmitted.

3. Transmission (1) according to Claim 1 or 2, char-acterized in that, when the pulleys (P, S) are at astandstill, the pinching force of the driven pulley (S)is proportional to the pinching force required in or-

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der to maintain a desired transmission ratio at a giv-en pinching force of the drive pulley (P).

4. Transmission (1) according to Claim 1, 2 or 3, char-acterized in that, auxiliary mechanical means areprovided in order to prevent the transmission (1)from shifting while at a standstill and during initial

revolution of the said pulleys (P, S).

5. Transmission (1) according to Claim 4, character-ized in that the auxiliary means act on the drivenpulley (S).

6. Transmission (1) according to any of the precedingclaims, characterized in that the transmission (1)is controlled as if it were at a standstill state until aminimum of one revolution of the driven pulley (S),preferably until between at least one full revolutionof the belt (7) and a number of revolutions of thebelt (7).

7. Transmission (1) according to any of the precedingclaims, characterized in that the transmission (1)is controlled as if it were at a standstill state at thelatestuntil thedrivenpulley (S), ora vehicle in whichthe transmission is applied, has reached a prede-termined minimum speed.

8. Transmission (1) according to any of the precedingclaims, characterized in that, the transmission (1)is provided with antislip detection and controlmeans andwith signalling means which aresuitablefor electronic feedback to an electronically control-

led drive unit (M), for example an internal combus-tion engine (M).

9. Drive train comprising a drive unit (M), for examplean internal combustion engine (M), and the contin-uously variable transmission (1) according to anyoneof the preceding claims, characterized in that,the drive unit (M) is regulated in such a manner thatthe maximum torque delivered by the unit (M) is lim-ited to a predetermined maximum until a detected,predetermined speed of a vehicle in which the driveunit (M) is applied, or of the driven pulley (S), isreached.

Patentansprche

1. Kontinuierlich variables Getriebe (1), das mit einerAntriebsscheibe (P) und einer Abtriebscheibe (S)versehen ist, wobei jede wenigstens eine axial ver-schiebbare Platte (4, 10) hat, damit ein endlosesbertragungselement oder ein Riemen (7) zwi-schen den Platten (3, 4; 9, 10) einer Scheibe (P, S)eingeklemmt werden kann, welches derart ange-ordnet ist, da ein Drehmoment zwischen den

Scheiben (P, S) bertragen wird, wobei das Getrie-be (1) wenigstens whrend des normalen Betriebsbei voller Bewegung der Scheiben (P, S) durch einSteuerverfahren derart gesteuert wird, da dieKlemmkraft derAntriebsscheibe (P) von der an denRiemen (7) ber die Antriebsscheibe (S) aufge-brachten Klemmkraft abhngt, wobei dieseKlemm-

kraft wenigstens teilweise als eine Funktion eineszu bertragenden Drehmomentsbestimmt ist, wh-rend der Druck in der Zylinderkammer (5) der An-triebsscheibe (P) mittels einesHydraulikventils (23)gesteuert wird, um ein bersetzungsverhltnis ein-zustellen, wobei das Steuerverfahren derart aufge-baut ist, da es den Zustand erkennt, in welchemdasGetriebe(1)aus einem Stillstand gestartetwird,dadurch gekennzeichnet, da das Getriebe (1)auf ein solche Weise angepat ist, da, whrenddie Scheiben (P, S) im Stillstand sind und vor demoben erwhnten Steuerverfahren bei voller Bewe-gung, ein zu bertragendes Drehmoment mit von

der Antriebsscheibe (P) auf den Riemen (7) aufge-brachten Klemmkraft bertragen wird, indem Druckin die Zylinderkammer (5) der Antriebsscheibe (P)durch die Aktivierung des Hydraulikventils (23) auf-gebracht wird.

2. Getriebe (1) nach Anspruch 1, dadurch gekenn-zeichnet, da die Klemmkraft der Antriebsscheibe(P) der Klemmkraft entspricht, die erforderlich ist,um das zu bertragende Drehmoment berzulei-ten.

3. Getriebe (1) nach Anspruch 1 oder 2, dadurch ge-

kennzeichnet, da dann, wenn dieScheiben (P, S)im Stillstand sind, die Klemmkraft der Antriebs-scheibe (S) proportional zu der Klemmkraft ist, dieerforderlich ist, um ein gewnschtesbersetzungs-verhltnis bei einer gegebenen Klemmkraft der An-triebsscheibe (P) aufrechtzuerhalten.

4. Getriebe (1) nach Anspruch 1, 2 oder 3, dadurchgekennzeichnet, da mechanische Hilfsmittel vor-gesehen sind, um zu verhindern, da das Getriebe(1) bei einem Stillstand und whrend einer anfng-lichen Drehung der Scheiben (P, S) schaltet.

5. Getriebe (1) nach Anspruch 4, dadurch gekenn-zeichnet, da die Hilfsmittel auf die Antriebsschei-be (S) wirken.

6. Getriebe (1) nach einem der vorhergehenden An-sprche, dadurch gekennzeichnet, da das Ge-triebe (1) bis mindestens einer Umdrehung der Ab-triebscheibe gesteuert wird, als ob es in einem Still-standzustand wre,bevorzugt bis wenigstens einervollen Umdrehung des Riemens (7) und einer An-zahl von Umdrehungen des Riemens (7).

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7. Getriebe (1) nach einem der vorhergehenden An-sprche, dadurch gekennzeichnet, da das Ge-triebe (1) gesteuert wird, als ob es in einem Still-standzustand wre, sptestens bis die Abtrieb-scheibe (S) oder ein Fahrzeug, in welchem das Ge-triebe verwendet wird, eine vorbestimmte minimaleGeschwindigkeit erreicht hat.

8. Getriebe (1) nach einem der vorhergehenden An-sprche, dadurch gekennzeichnet, da das Ge-triebe (1) mit Antischlupferfassungs- und -steuer-mitteln sowie mit Signalgabemitteln versehen ist,die fr eine elektronische Rckkopplung zu einerelektronisch gesteuerten Antriebseinheit (M), bei-spielsweise einem Verbrennungsmotor (M), geeig-net sind.

9. Antriebsstrang mit einer Antriebseinheit (M), bei-spielsweise einem Verbrennungsmotor (M), unddem kontinuierlich variablen Getriebe (1) nach ei-

nem der vorhergehenden Ansprche, dadurch ge-kennzeichnet, da die Antriebseinheit (M) auf sol-che Weise geregelt wird, da das von der Einheit(M) gelieferte maximale Drehmoment auf ein vor-bestimmtes Maximum begrenzt ist,bis eine erfate,vorbestimmte Geschwindigkeit eines Fahrzeugs, inwelchem die Antriebseinheit (M) verwendet wird,oder der Abtriebscheibe (S) erreicht ist.

Revendications

1. Transmission variation continue (1), comprenant

une poulie d'entranement (P) et une poulie rcep-trice (S), chacune d'elles possdant au moins undisque (4, 10) mobile axialement afin de pouvoirpincer un lment ou une courroie de transmissionsansfin (7) entrelesdisques (3, 4 ; 9,10) d'une pou-lie(P ; S),configure de faon transmettre un cou-pleentreles poulies (P ; S),la transmission (1)tantcontrleparun procd de contrle au moins pen-dant le fonctionnement normal lors d'un mouve-ment complet de la poulie (P, S), de telle sorte quela force de pincement de la poulie d'entranement(P) dpend de la force de pincement applique lacourroie (7)via la poulierceptrice (S), don't la force

de pincement est dtermine, au moins en partie,en tant que fonction d'un couple devant tre trans-mis, tandis que la pression rgnant dans la cham-bre de cylindre (5) de la poulie d'entranement (P)est contrle au moyen d'une soupape hydraulique(23) pour dterminer un rapport de transmission, leprocd de contrle tant rgl pour reconnatrel'tat dans lequel la transmission (1) est mise enroute partir d'un tat arrt, caractrise en ceque la transmission (1) est adapte de telle sorteque lorsque les poulies (P, S) sont dans un tat ar-rt et, avant le procd de contrle mentionn ci-

dessus, misen oevre lors d'un mouvementcomplet,un couple transmettreest transmis avec uneforcede pincement applique la courroie (7) par la pou-lie d'entranement (P), en appliquant une pressiondans la chambre de cylindre (5) de la poulie d'en-tranement (P) via l'activation de la soupape hy-draulique (23).

2. Transmission (1) selon la revendication 1, caract-rise en ce que la force de pincement de la poulied'entranement (P) correspond la force de pince-ment requise pour transfrer le couple devant tretransmis.

3. Transmission (1) selon la revendication 1 ou 2, ca-ractrise en ce que lorsque lespoulies (P, S) sontdans untatarrt, laforce depincement dela pou-lie rceptrice (S)est proportionelle la force de pin-cement requise pour maintenir un rapport de trans-mission souhait pour une force de pincementdon-

ne de la poulie d'entranement (P).

4. Transmission (1) selon la revendication 1, 2 ou 3,caractrise en ce que des moyens mcaniquesauxiliaires sont prvus pour empcher la transmis-sion de bouger lorsqu'elle est l'tat arrt et pen-dant la rotation initiale desdites poulies (P, S).

5. Transmission (1) selon la revendication 4, caract-rise en ce que les moyensauxiliaires agissent surla poulie rceptrice (S).

6. Transmission (1) selon l'unequelconque des reven-

dications prcdentes, caractrise en ce que latransmission (1) est contrle comme si elle taitdans un tat arrtt jusqu' un minimum d'une ro-tation de la poulie rceptrice (S), de prfrence en-tre au moins une rotation complte de la courroie(7) et un certain nombre de rotations de la courroie(7).

7. Transmission (1) selon l'unequelconque des reven-dications prcdentes, caractrise en ce que latransmission (1) est contrle comme si elle taitdans un tat arrtt au plus tard jusqu' ce que lapoulie rceptrice (S), ou un vhicule dans lequelest

installe la transmission, ait atteint une vitesse mi-nimum prdtermine.

8. Transmission (1) selon l'unequelconque des reven-dications prcdentes, caractrise en ce que latransmission est pourvue de moyens de dtectionet de contrle antipatinage et de moyens de signa-lisation adapts un retour lectronique vers uneunit motrice contrle lectroniquement (M), parexample un moteur combustion interne (M).

9. Groupe motopropulseur comprenant une unit mo-

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trice (M), par example un moteur combustion in-terne (M), et la transmission variationcontinue (1)selon l'une quelconque des revendications prc-dentes, caractrise en ce que l'unit motrice (M)est rgule de telle sorte que le couple maximumfourni par l'unit (M) est limit un maximum pr-dtermin jusqu' ce que l'on atteigne une vitesse

prdtermine et dtecte du vhicule dans lequelse trouve l'unit motrice (M), ou de la poulie rcep-trice (S).

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EP0937914B1transmission Puissances Transmission

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Transcript of EP0937914B1transmission Puissances Transmission