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

6

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

13

“power plant”

engine=

pump+

hydraulic circuit

14

lift cylinders

hydraulic transformer

hydraulic circuit

15

tilt cylinder

hydraulic circuit

16

steeringcylinders

hydraulic circuit

17

drive

auxiliaries

18

new technologies

two new technologies

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floating cup principle

hydraulic transformer

floating cup

20

❖ compact

❖ low torque ripple

❖ high starting torque

❖ low noise

❖ low cost

❖ efficient

floating cup principle

21

transformersmechanical electrical

T ⋅ω( )in = T ⋅ω( )out V ⋅I( )in = V ⋅I( )out

hydraulic

p ⋅Q( )in = p ⋅Q( )out

Hydraulic transformation

23

(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

24

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

26

flow Q

pressure p

QA

(pB, QB)

pA(pA, QA)

QB

pB

❖ efficient

❖ recuperative

❖ amplification

Hydraulic transformation

27

speed

control angle

❖ efficient

❖ recuperative

❖ amplification

❖ dynamic

forward propulsion

forward braking

reverse propulsion

reverse braking

Hydraulic transformation

28

❖ efficient

❖ recuperative

❖ amplification

❖ dynamic

❖ 4-quadrants

forward propulsion

forward braking

reverse propulsion

reverse braking

Hydraulic transformation

29

❖ efficient

❖ recuperative

❖ amplification

❖ dynamic

❖ 4-quadrants

❖ wide operating range

Pmax

new technologies

30

hydraulic transformersfloating cup pump/motor

31

50% fuel consumption?

most important reasons

32

❖ high component efficiency

❖ energy recuperation

❖ avoiding throttle losses

❖ eliminating the torque converter

propulsion (excl. engine)

33

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)

34

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

39

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%

40

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