12_eehpc-28-nov
TRANSCRIPT
-
7/30/2019 12_eehpc-28-nov
1/17
Product Development & Global Technology
An Introduction to Hydro-
mechanical Transmissions
Mike Cronin
28 Nov 2012(Previously titled: Cost Savings With Hydro-mechanical Transmissions)
-
7/30/2019 12_eehpc-28-nov
2/17
Product Development & Global Technology
Introduction
Topics Covered: Speaker Background
Simple Hydro-mechanical Transmission Schematic Current Industry Examples Important Design Characteristics
How Fuel Is Saved Other Beneficial Characteristics
Caveats: Not A Design Guide Limited To Off-road Perspective
Hydro-mechanical transmission architectures are growing in popularity as acost effective means to provide continuously variable transmission (CVT)
functionality in the heavy-duty off-road market segment. This presentation willintroduce the audience to the basics of operation and commonly used terms.
-
7/30/2019 12_eehpc-28-nov
3/17
Product Development & Global Technology
Mike Cronins CV J oined Caterpillar upon graduation from Michigan State University with a
BSME in 1973
Entire career working on off-road drivetrain performance and design: Hydro-mechanical transmissions for a broad range of applications Electric drive for TTT
TTT & Belted machine steering systems and components Assorted lower powertrain projects
Assorted powershift transmission concepts
Drivetrain related patents 23 Granted
10 Pending 9 Notifications
Retired in 2010
Rejoined Caterpillars Drivetrain Research Dept on a part time basis tocontinue work on hydro-mechanical drivetrains.
-
7/30/2019 12_eehpc-28-nov
4/17
Product Development & Global Technology
EngineGear
System
Gear
System
Variator
Transfer Gear
And/or Axle
Reductions
Wheel
Or
Sprocket
Transmission
General Parallel Path Transmission Schematic
a.k.a. Split Torque, Power Split, Hydro-mechanical, Electro-mechanical etc.
A variator is a device that can vary the speed or torque ratioacross its two shafts in a continuous manner.
Several types are available: hydraulic, electric, traction etc.
In addition to gears these systems may contain clutches,brakes or other familiar transmission componentsconnected in various ways.
A very large number of combinations are possible.
There must be at leastone planetary
PlanetaryGear
System
Hydraulic Power Path
Mechanical Power Path
-
7/30/2019 12_eehpc-28-nov
5/17
Product Development & Global Technology
Speed 1
Speed 2
General Planetary
Gear System
Planetaries Are Splitters and Adders
Output speed is the sumof the input speeds.
Output Speed =
A*Speed1+
B*Speed2
Speed
Adder
TorqueSplitter
Output Torque1 = A*Torque
Output Torque2 = B*Torque
Torque
-
7/30/2019 12_eehpc-28-nov
6/17
Product Development & Global Technology
Engine FinalDrive
Wheelsor
Tracks
Pump Motor
Hydro-Mechanical CVT
EngineSpeed
General PlanetaryGear System
Variable
Speed
Output Speed =
A*Engine Speed+
B*Variable Speed
Even if engine speed isconstant, if the other speedis variable then the output
speed is still variable.
Hydrostatic Variator Shown
-
7/30/2019 12_eehpc-28-nov
7/17
Product Development & Global Technology
Why choose hydro-mechanical?
Scaling Variators are only available in a limited number of sizes. A given size variator matches to a larger machine when used in a hydro-
mechanical configuration.
Larger machines now have access to CVT behavior.
Efficiency The power path carries a fraction of engine power Less hydraulic power means fewer losses.
Less fuel More power to ground
Cost Most cost effective CVT technology for 200-400 hp wheel loaders.
-
7/30/2019 12_eehpc-28-nov
8/17
Product Development & Global Technology
Hydro-mechanical Transmission Examples
AG
IVTEccom/IVT/S-maticVario
IVT CVT
-
7/30/2019 12_eehpc-28-nov
9/17
Product Development & Global Technology
Hydro-mechanical Transmission Examples
Wheel Loader
Cat
CVT
Dana/Rexroth
HVT
ZF
cPower
-
7/30/2019 12_eehpc-28-nov
10/17
Product Development & Global Technology
Important Design Differentiators
Variator Type Discussed Above
Coupling Type Input Output Compound Split
Number of Ranges or Modes One
Two Three Four
-
7/30/2019 12_eehpc-28-nov
11/17
Product Development & Global Technology
-
7/30/2019 12_eehpc-28-nov
12/17
Product Development & Global Technology
Variable Pump
Fixed Motor
Integrated, Inline Package
Used in ZF Designed cPower Shown @ 2010 Bauma
Variable Pump
Variable Motor
Pump and Motor Displacements Linked
Motor Displacement Decreases while PumpDisplacement Increases
Integrated, U Package
Variator Examples
-
7/30/2019 12_eehpc-28-nov
13/17
Product Development & Global Technology
Input Coupled/ Output Split
In Out
PlanetaryGear
System
Double Coupled/ Unsplit
In Out
PlanetaryGear
System
Output Coupled/ Input Split
In Out
PlanetaryGear
System
Uncoupled/ Compound Split
In Out
PlanetaryGear
System
Explaining the term Coupled
The Variator is Coupled to theOutputThe Variator is Coupled to the Input
Cat CVT
JD 6000, 7000 IVT
S-Matic
Graziano
Fiat/Ag
ZF Eccom
Rexroth HVT 2nd,3rd
914
ST125 1st
Rexroth HVT 1st
D6E
D7E
795AC
Vario
8000 IVT 1st,3rd
ZF CP
Prius
Dual Mode/AHSII/EP40 1st
8000 IVT 2nd,4th
ZF CP 2nd,3rd
Dual Mode/AHSII/EP40 2nd
Hydraulic
Variators
Electric
Variators
Volt
-
7/30/2019 12_eehpc-28-nov
14/17
Product Development & Global Technology
Engine Speed vs Ground Speed
w Discrete Step Transmission
600
800
1000
1200
1400
1600
1800
2000
2200
0 5 10 15 20 25
Ground Speed mph
EngineSpeedrpm
Discrete Ratio Powertrain Schematic
Engine Transmission
Aux Loads
Discrete Ratio Transmission
Several selectable gear ratios
Slipping clutch for launch
Transfer Gear
And /or Axle
Reductions
Wheel
Or
Sprocket
Ground Speed 2
One Engine Speed
Possible atGround Speed 2
Ground Speed 1
Two Engine Speeds
Possible at Ground
Speed 1
-
7/30/2019 12_eehpc-28-nov
15/17
Product Development & Global Technology
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
Engine Speed rpm
EngineGrossPo
werkW
Hypothetical Engine Fuel Rate Contours
g/min
800-900
700-800
600-700
500-600
400-500
300-400
200-300
100-200
0-100
Approximate Minimum
Fuel Consumption
Ground Speed 1 Ground Speed 2
-
7/30/2019 12_eehpc-28-nov
16/17
Product Development & Global Technology
Continuously Variable Ratio Powertrain Schematic
Engine Transmission
Aux Loads
Continuously Variable Transmission
Ratio co ntinuously managed forperformance and launch
Transfer Gear
And /or Axle
Reductions
Wheel
Or
Sprocket
Engine Speed vs Ground Speed
600
800
1000
1200
1400
1600
1800
2000
2200
0 5 10 15 20 25
Ground Speed mph
EngineSpeed
rpm
Functional Defin ition of CVT:
Engine speed can be placed and maint ained at the
desired level regardless of grou nd speed.
Any Engine Speed
Possible at Any
Ground Speed
-
7/30/2019 12_eehpc-28-nov
17/17
Product Development & Global Technology
END