Vehicle Transaxle Oil Routing Using Temperature-Dependent Flow Bias

Solution Overview

Problem

Existing powertrain systems for vehicles face inefficiencies in fluid distribution for lubrication and cooling, particularly in transaxles, where temperature-dependent fluid flow management is not effectively addressed, leading to suboptimal performance and increased power consumption.

Innovation Solution

A transaxle design with a housing that includes both lubrication and cooling channels branching from a common inlet, featuring an orifice plate that directs fluid flow based on temperature, ensuring that fluid is biased towards lubrication at lower temperatures and towards cooling at higher temperatures, optimizing fluid distribution without the need for valve systems and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a valve system is used to control fluid distribution between lubrication and cooling channels, then fluid flow can be precisely controlled, but device complexity and power consumption increase

Engineering Contradiction:

Improvefluid flow controlVSAvoidvalve system

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The system uses the fluid's own temperature to automatically control its distribution. The temperature-dependent viscosity changes cause the fluid to naturally redirect between lubrication and cooling channels based on thermal conditions, eliminating the need for external control systems

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent exploits changes in fluid viscosity as a parameter that varies with temperature. At different temperatures, the viscosity changes cause the fluid to preferentially flow through different channels, using physical property changes rather than mechanical control

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a valve system is used to control fluid distribution between lubrication and cooling channels, then fluid flow can be precisely controlled, but power consumption increases

Engineering Contradiction:

Improvefluid flow controlVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The system uses the fluid's own temperature to automatically control its distribution. The temperature-dependent viscosity changes cause the fluid to naturally redirect between lubrication and cooling channels based on thermal conditions, eliminating the need for external control systems

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical valve systems with a thermal-fluid dynamic mechanism where temperature-dependent viscosity naturally controls flow distribution, substituting active mechanical control with passive physical phenomenon-based control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Temperature

If fluid flow is increased for cooling at high temperatures, then cooling effectiveness improves, but lubrication may be compromised at lower temperatures

Engineering Contradiction:

Improvecooling effectivenessVSAvoidlubrication stability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent exploits changes in fluid viscosity as a parameter that varies with temperature. At different temperatures, the viscosity changes cause the fluid to preferentially flow through different channels, using physical property changes rather than mechanical control

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system dynamically adjusts fluid distribution based on operating conditions. The flow partitioning between lubrication and cooling channels automatically changes in response to temperature variations, providing adaptive control without mechanical actuators

Inventive Principle:

Principle #15Dynamics

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

This design enhances fluid distribution efficiency by adjusting flow based on temperature, maintaining stable lubrication while increasing cooling flow at high temperatures, thus improving transaxle performance and reducing power usage, particularly at lower temperatures.

Implementation Method 1

The fluid is biased toward the lubrication channel in response to a temperature of the fluid being less than a threshold. The fluid is biased toward the cooling channel in response to the temperature of the fluid being greater than the threshold

Methodology Applied

Scientific EffectTemperature-dependent viscosity: Viscometer

Data Source

PatentUS11754169B1Lubrication and cooling oil distribution system for a vehicle transaxle

Publication Date: 2023.09.12 FORD GLOBAL TECH LLC

AI summary

A vehicle transaxle includes a housing, an electric machine, and rotating components. The housing defines an internal cavity, a first channel, and a second channel. The first and second channels branch from a common inlet. The electric machine and rotating components are disposed within the internal cavity. The first channel is configured to deliver fluid to the electric machine for cooling. The second channel is configured to deliver the fluid to the rotating components for lubrication. The cooling channel is sized relative to the lubrication channel such that the fluid is biased from the inlet and toward the second channel in response to a temperature of the fluid being less than a threshold and is biased from the inlet and toward the first channel in response to the temperature of the fluid being greater than the threshold.