Post on 26-Jan-2021
Hydrid wheel loader
The 1st VDI conference, Transmissions in Mobile Machines, Friedrichshafen, Germany June 7-8, 2011
Dr.-Ing. Peter Achten, Dipl.-Ing. Georges Vael Innas, Breda, the Netherlands
Tekn.-Lic. Kim Heybroek Volvo Construction Equipment, Eskilstuna, Sweden
Volvo
a ‘hybrid’ cooperation
Innas
2
3
maximum traction 240 kN
maximum speed 45 km/h
engine power 274 kW
fuel tank 335 l
OIL
335 l
3000 kWh
4
≈1 kWh
≈ 0.1 kWh
Hybrid?
5
Hydraulic + Hybrid =Hyd rid
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Hydrid
7
simulation study
starting points
❖ 30 metric tonnes wheel loader
❖ short loading cycle (Y-cycle)
8
Hydrid wheel loader
same engine
same performance
Hydrid wheel loaderdecoupling the engine
hydraulic accumulators
efficient ‘floating cup’ pumps & motors
hydraulic transformers
10
11
new hydraulic circuit
hydraulic circuit
12
common pressure rail (CPR)
hydraulic circuit
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“power plant”
engine=
pump+
hydraulic circuit
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lift cylinders
hydraulic transformer
hydraulic circuit
15
tilt cylinder
hydraulic circuit
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steeringcylinders
hydraulic circuit
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drive
auxiliaries
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new technologies
two new technologies
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floating cup principle
hydraulic transformer
floating cup
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❖ compact
❖ low torque ripple
❖ high starting torque
❖ low noise
❖ low cost
❖ efficient
floating cup principle
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transformersmechanical electrical
T ⋅ω( )in = T ⋅ω( )out V ⋅I( )in = V ⋅I( )out
hydraulic
p ⋅Q( )in = p ⋅Q( )out
Hydraulic transformation
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(pA, QA)
(pT, QT)
(pB, QT)
flow Q
pressure p
p⋅Q = constant
QA
(pB, QB)
pA(pA, QA)
QT = QB - QA
QB
pB
Hydraulic transformation
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flow Q
pressure p
QA
(pB, QB)
pA(pA, QA)
QB
pB
❖ efficient
Hydraulic transformation
25
flow Q
pressure p
QA
(pB, QB)
pA(pA, QA)
QB
pB
❖ efficient
❖ recuperative
Hydraulic transformation
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flow Q
pressure p
QA
(pB, QB)
pA(pA, QA)
QB
pB
❖ efficient
❖ recuperative
❖ amplification
Hydraulic transformation
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speed
control angle
❖ efficient
❖ recuperative
❖ amplification
❖ dynamic
forward propulsion
forward braking
reverse propulsion
reverse braking
Hydraulic transformation
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❖ efficient
❖ recuperative
❖ amplification
❖ dynamic
❖ 4-quadrants
forward propulsion
forward braking
reverse propulsion
reverse braking
Hydraulic transformation
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❖ efficient
❖ recuperative
❖ amplification
❖ dynamic
❖ 4-quadrants
❖ wide operating range
Pmax
new technologies
30
hydraulic transformersfloating cup pump/motor
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50% fuel consumption?
most important reasons
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❖ high component efficiency
❖ energy recuperation
❖ avoiding throttle losses
❖ eliminating the torque converter
propulsion (excl. engine)
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wheels&
brakes
mech.transmission
wheels&
brakes
brakes
torque converter
accumulatorstransformersmotors
CPR-system
conventional Hydrid
64% reduction of losses
pump losses
pump
valves
cylinders
cylinders (excl. engine)
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cylinders
valves
accumulatorstransformersvalves
CPR-system
pump
pump losses
conventional Hydrid
88% reduction of losses
pumps
pump losses
engine efficiency
35
speed [rpm]0 500 1000 1500 2000 2500
0
500
1000
1500
2000
torq
ue [
Nm
]
15%20%30%
35%
38%
40%
195 kW
conventional
engine efficiency
36
speed [rpm]0 500 1000 1500 2000 2500
0
500
1000
1500
2000
torq
ue [
Nm
]
15%20%30%
35%
38%
40%
101 kW
Hydrid
engine efficiency
37
speed [rpm]0 500 1000 1500 2000 2500
0
500
1000
1500
2000
torq
ue [
Nm
]
15%20%30%
35%
38%
40%
195 kW
101 kW
about equal average efficiency
38
Results
Results
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average engine power
losses drive train (excl. ICE)
losses hydraulic circuit (excl. ICE)
cooler demand transmission & hydraulic circuit
0% 50% 100%
conventionalHydrid
-48%
-88%
-80%
Y-cycle only!
-64%
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