Georgia Institute of Technology | Milwaukee School of Engineering | North Carolina A&T State University | Purdue University

University of Illinois, Urbana-Champaign | University of Minnesota | Vanderbilt University

Project 1J.2 :A Novel Vane Pump Power

Split Transmission

Researchers: Biswaranjan Mohanty,

Emma Frosina, Feng Wang,

Mike Gust

PI: Professor Kim A. Stelson

Center for Compact and Efficient Fluid Power

Department of Mechanical Engineering

University of Minnesota

FPIRC, Chicago, October 14-16, 2015

2

Outline

1. Introduction

2. Vane Pump Power Split Transmission (VPPST)

Vane Power Split Unit (VPSU)

VPPST function

3. VPPST for a Pickup truck

4. CFD Simulation of the VPSU

5. Conclusions

3

Introduction

Hydraulic CVTs – Hydrostatic Transmissions are widely used in off-road applications.

CVT allows for efficient engine operation

High power density allows for lower vehicle weight, faster acceleration.

With a hydraulic accumulator, regenerative braking and full engine management became

possible

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• http://www.altairbusolutions.com/

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hybrid delivery vehicle

Altair’s series hydraulic hybrid

city bus (LCO-140H)

Reduce emission by up to 40% 30% more mileage

4

Introduction

Conventional HST

Simple, clean, efficient and cost effective

The efficiency of the HST is less than gear transmission

Inefficient due to the pump and motor inefficiencies at

partial displacement

Advantages of A hydro-mechanical transmission (HMT)

Continuous transmission ratio of an HST

High efficiency of the gear box

HMT

Gearbox HST

High

efficiencyCVT

A popular gearbox used in an HMT is the planetary

gear set (PGS) – balanced design but bulky, heavy

complicated and expensive

5

Vane Pump Power Split Transmission

(VPPST)

VPPST schematic

The hydraulic power of the VPSU is added to the drive shaft through variable

displacement motor to amplify the torque.

T d = T m + (Pc Dm/2π)

The power sharing between mechanical and hydraulic path of the VPPST is controlled

by the displacement of the variable motor.

VPSU

Variable motor

Input shaft

Output shaft

Hydraulic Path

VPSU

Input

shaftOutput

shaft

Variable

motor

T p ,ωp

T m ,ωm

Pc ,Qc

D p

D m

T d ,ωm

6

Vane Power Split Unit

Rotor/vane

(input shaft) Floating ring

(output shaft)

Outlet chamber

(pressure control)

Inlet chamber

(tank)

Based on a balanced design double-acting vane pump, longer life time and quieter in

operation

Function like a conventional HST but is much simpler and more compact.

The Integrated clutch

The vanes can be fully retracted through the tapered pins actuated by pilot pressure.

The parasitic loss when vane is retracted is very low.

HYDRAULIC

PILOT SIGNAL

TAPERED

PUSH PIN

BALL

DETENT

GROOVE

VANE

ROTOR

7

Vane Power Split Unit (VPSU)

Output shaft torque is the sum of the pressure induced

hydraulic torque and the viscous torque.

The viscous torque helps to drive the floating

ring/output shaft in a VPSU, while being wasted in a

conventional HST.

vd

hd

vF

'

vF

Inlet chamber

Outlet chamber

hF

hA

vA

'

hF

Hydraulic torque

The hydraulic flow depends on relative rotary speed

between input and output speed.

Qc= D p (ωp- ωm)

8

Design of Transmission for a pick-up truck

Operation modes

Cruising Speed : 160 Km/hr

Acceleration Performance:

0-96.5 Km/hr in 6 sec.

Climbing Performance:

Towing Performance:

Gross Vehicle Weight 2925 kg

Gross Combined Weight 5210 Kg

Diameter of Wheel 0.7608 m

Frontal Area (A) 3.883 m2

Rolling resistance Coefficient (K1) 0.045

Drag Coefficient (Cw) 0.360

Air Density (ρ) 1.225 Kg/m3

Parameters of a Pick-up Truck

Wheel Requirement:

Wheel Torque: 5785 Nm

Maximum Speed: 160 Km/hr

Engine Selected:

Power: 217 Kw @ 5700 rpm

Torque: 433 Nm @ 4000 rpm

Gear Ratio Required:

Max: 13.36 ; Min: 1.49

9

Performance of the VPPST

Parameter Value

Displacement Pump (Dp) 82 cc/rev

Displacement Motor (Dm) 200 cc/rev

Final Drive Ratio (Gf) 2.17

Motor Mounting Gear (Gm) 2.275

Intermediate Gear (GI) 0.63,1.03

10

Simulation

Quasi-static Inverse simulation method is used to study the performance of the

concept and optimization of the design parameters

Vehicle speed and acceleration data of the drive cycle is used as input

Urban Dynamometer Driving Schedule (UDDS)

Highway Fuel Economy Driving Schedule (HFEDS)

Constant efficiency is assumed for the hydraulic pump and motor

VPSU: 85% Variable Motor: 90%

11

Performance Result (UDDS)

Most of the time engine

operates on the optimal

curve for minimum fuel

consumption.

During deceleration and

when the VPSU output

speed exceed the input

speed , the engine is unable

to achieve the optimal curve.

Acceleration: saturated

by maximum

displacement

Deceleration:

saturated by zero

displacement

12

The motor speed in UDDS

cycle is 208.3 rad/sec,

which is far less than the

rated maximum speed.

The motor operates at full

displacement to achieve the

required acceleration

The hydraulic operating

pressure is always less than

operating pressure of the

VPSU.

Performance Result (UDDS)

13

3D CFD – VANE PUMP

Pump Geometry

Fluid Volume

14

Simulation

Fluid Properties

• Mobile DTETM

• Density: 876 kg/m3

• Viscosity: 0.03 PaS

• Toil= 40 °C (104 °F)

• Air = 2%

Operating Conditions

• Inlet shaft Speed: 2400 rpm

• Output shaft Speed: 0-2400 rpm

• Poutlet = 34 bar & 100 bar

• Pinlet = Patm = 1 bar

15

0 60 120 180 240 300 360Angle [Deg]

0

4000

8000

12000

16000

20000

Po

wer

[W]

Input_Power_103.4bar

Output_Power_103.4bar

Input_Power_34.5bar

Output_Power_34.5bar

Output Pressure Variation

PRESSURE

(bar)35 100

Pin (W) 5201.2 13541.2

Pout (W) 3175.9 11363.0

Pflow (W) 1093.9 1103.6

η 0.82 0.92

Input Speed: 2400 rpm

Output Speed: 2000 rpm

η=𝑃𝑜𝑢𝑡+𝑃𝑓𝑙𝑜𝑤

𝑃𝑖𝑛

16

Input Speed: 2400 rpm

Output Speed: 400,1200,2000rpm

Pressure:

η=𝑃𝑜𝑢𝑡+𝑃𝑓𝑙𝑜𝑤

𝑃𝑖𝑛

0 60 120 180 240 300 360Angle [Deg]

0

2000

4000

6000

Po

wer

[W]

Output_Power_400rpm

Output_Power_1200rpm

Output_Power_2000rpm

OUTPUT

SPEED

(rpm)

400 1200 2000

Pin (W) 6413.7 5748.6 5201.2

Pout (W) 1115.1 2947.8 3175.9

Pflow (W) 1631 460.8 1093.9

η 0.43 0.59 0.82

Output Pressure Variation

17

Vane tip gap variation

Input Speed: 2400 rpm

Output Speed: 2000rpm

Pressure:

0 60 120 180 240 300 360Angle [Deg]

0

1000

2000

3000

4000

5000

6000

7000

8000

Po

wer

[W]

Output_Power_No_Gap

Output_Power_0.01mm

Output_Power_0.037mm

GAP (mm) 0 0.01 0.04

Pin (W) 5255.2 5201.2 267.5

Pout (W) 4291.9 3175.9 143.6

Pflow (W) 735.1 1093.9 35.9

η 0.95 0.82 0.67

18

What’s Next…

VPSU proto type (66 cc/rev)

Optimization of the VPSU

Plate

Rat Tail

Vane Tip

Ring

Port

19

Integral Clutch System

Hybridization of the transmission, by adding an accumulator for regenerative

braking and better engine management.

Development of a dynamic model of the system and a control strategy for the

engine management.

What’s Next…

20

Conclusions

The VPSU is based on a double-acting vane pump with floating ring. It has long

life and quiet operation. It has an integrated clutch.

The VPSU combines the pumping and motoring in one unit, reduces the

parasitic losses in the pump and motor and eliminates line losses in between,

making the unit simple and efficient.

VPPST can be designed with a VPSU and a variable motor

All the performance requirements of the pickup truck can be achieved by

combining a two stage gear box with a 82 cc/rev VPSU and a mid size variable

motor (200cc/rev).

3D simulation results shows, efficiency increases with increase in pressure and

output shaft speed. The simulation results need to be validated through

experimental setup

21

Feng Wang

University of Minnesota

Kim A. Stelson

University of Minnesota

Mike Gust

University of Minnesota

Thank you!

Emma Frosina

University of Naples Federico II

Biswaranjan Mohanty

University of Minnesota

Norm Mathers

Mathers Hydraulics