Rear Axle Pump for Lubricant Density Control
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Solution Overview
Problem
Hypoid gear arrangements experience high friction and fluid turbulence losses due to high lubricant density during cold starts, leading to increased packaging complexity and reduced fuel efficiency in wet bath lubrication systems.
Innovation Solution
A pump system is integrated into the lubricant sump of a rear axle, capable of operating in two directions: one direction to direct lubricant to a cooler and the other to entrain gas with the lubricant, reducing its density and minimizing turbulence, with temperature-sensitive valve control to optimize operation based on lubricant temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet bath lubrication is used for hypoid gear arrangements, then friction is reduced and lubrication is improved, but packaging complexity and cost increase
Solution Approach 1:
The pump is integrated directly into the sump structure, merging the lubricant circulation pump and sump into a single integrated component. This eliminates the need for separate pump housings and mounting structures, thereby reducing packaging complexity while maintaining wet bath lubrication effectiveness.
2Reliability
If lubricant temperature is low during cold start, then lubrication is provided, but fluid turbulence losses increase due to high lubricant density
Solution Approach 1:
The system changes the physical parameter of lubricant density by entraining gas bubbles during cold start conditions. This reduces lubricant density and consequently decreases fluid turbulence losses while maintaining adequate lubrication for hypoid gear arrangements.
Solution Approach 2:
The pump operates in alternating directions periodically - forward direction during normal operation for cooling, and reverse direction during cold start to entrain gas. This periodic reversal allows the system to adapt to varying temperature conditions and optimize performance accordingly.
3Temperature
If pump operates continuously for lubricant cooling, then lubricant temperature is controlled, but fuel efficiency decreases
Solution Approach 1:
The pump operates periodically rather than continuously - activating in reverse direction only when cold start detection is triggered. This periodic operation based on temperature conditions reduces energy consumption and improves fuel efficiency while maintaining necessary lubricant temperature control.
Solution Approach 2:
The system uses the existing pump infrastructure to serve dual purposes - normal lubricant circulation and cold start gas entrainment. By utilizing the already-present pump component for temperature-dependent functions, the system avoids additional energy-intensive heating mechanisms.
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 solution decreases frictional drag and enhances fuel efficiency by adjusting lubricant density and temperature, reducing emissions and manufacturing costs while maintaining effective lubrication.
Implementation Method 1
a pump... configured to drive in a first direction to direct oil to an oil cooler and a second direction to entrain gas into lubricant in the sump
Implementation Method 2
the lubricant pump is configured to drive in a first direction to direct oil to an oil cooler
Data Source
AI summary
Methods and systems are provided for rear axle having a wet bath. In one example, a system comprises a pump configured to spin in a first direction to flow lubricant to a cooler and a second direction to entrain the lubricant with gas.