Electrohydraulic Torque Transfer Device with Temperature Control

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Solution Overview

Problem

Current power transmission devices for four-wheel drive vehicles are limited by size, weight, and packaging requirements, making them cost-prohibitive for certain applications, and there is a need for advanced technology to efficiently transfer torque between drivelines while managing clutch temperature effectively.

Innovation Solution

A power transmission device with a friction clutch actuated by an electric motor-driven gerotor, which provides pressurized fluid to a piston, allowing for adaptive torque modulation and temperature estimation using a controller that varies electrical energy supply via pulse width modulation and estimates clutch temperature based on engine coolant temperature changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a power transmission device is designed to transfer torque between drivelines in four-wheel drive vehicles, then torque transfer capability is improved, but size, weight and packaging requirements increase making the system cost-prohibitive

Engineering Contradiction:

Improvetorque transfer capabilityVSAvoidsystem weight and size

Core Design Contradiction:

PowerVSWeight of stationary object

Solution Approach 1:

The patent combines the torque transfer mechanism and temperature control system into a single integrated power transmission device. The fluid coupling mechanism merges torque transfer with thermal management functions, allowing the system to achieve four-wheel drive capability while reducing overall system size and weight by eliminating separate components.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If a friction clutch is used for torque transfer, then adaptive torque modulation is achieved, but clutch temperature increases causing thermal damage

Engineering Contradiction:

Improvetorque modulation capabilityVSAvoidclutch temperature

Core Design Contradiction:

Adaptability or versatilityVSTemperature

Solution Approach 1:

The patent introduces a fluid coupling mechanism as an intermediary between the friction clutch and the thermal environment. This fluid coupling acts as a thermal buffer that absorbs excess heat from the friction clutch during torque transfer, preventing thermal damage while maintaining adaptive torque modulation capability through electronic control.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces purely mechanical torque transfer with an electronically-controlled fluid coupling system. This substitution allows for adaptive torque modulation through electronic signals while the fluid coupling mechanism naturally manages thermal effects, eliminating the need for mechanical thermal management components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the controller continuously monitors and controls torque transfer, then torque transfer precision is improved, but energy consumption increases

Engineering Contradiction:

Improvetorque transfer precisionVSAvoidcontroller energy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The controller employs periodic monitoring and control actions rather than continuous operation. By sampling system parameters at intervals and updating torque transfer commands periodically, the system maintains precise torque transfer control while significantly reducing energy consumption compared to continuous monitoring and adjustment.

Inventive Principle:

Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables efficient and adaptive torque transfer between drivelines, reducing costs by optimizing system design and preventing thermal damage through accurate temperature management, thus enhancing the performance and reliability of four-wheel drive systems.

Implementation Method 1

The gerotor is operable to provide pressurized fluid to a piston acting on the friction clutch

Methodology Applied

Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

a friction clutch operable to selectively transfer torque between an input member and an output member

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

The controller estimates the temperature of the friction clutch at the time of being switched on based on a time that the controller has been off

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS8197386B2Electrohydraulic torque transfer device and temperature control system

Publication Date: 2012.06.12 AMERICAN AXLE & MANUFACTURING INC

AI summary

A power transmission device includes a friction clutch operable to selectively transfer torque between an input member and an output member. An actuator is operable to provide an actuating force to the friction clutch. The actuator includes an electric motor having an output shaft drivingly coupled to a pump. The pump is operable to provide pressurized fluid to a piston acting on the friction clutch. A controller that is switched on and off in response to an ignition signal estimates the temperature of the friction clutch at the time of being switched on based on a time the controller has been off. A method of estimating a temperature of the friction clutch is also disclosed.