Differential Axle Assembly with Sealed Housing and Bleed Flow Path
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Solution Overview
Problem
Work machines, particularly off-highway vehicles, face challenges in providing adequate lubrication to differential gear components while minimizing windage losses, which are reduced by immersing gears in lubricating liquid, but this leads to constrained cooling and lubrication capabilities.
Innovation Solution
A power train axle assembly with a differential gear housing that includes a fluid pressure actuated differential lock mechanism, a sealed outer periphery to maintain lubricant, and a bleed flow path for continuous lubricant flow, ensuring adequate lubrication and cooling of gears even under extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If differential gears are immersed in lubricating liquid to reduce windage losses, then windage losses are reduced, but the ability to cool and lubricate the differential gear assembly is challenged
Solution Approach 1:
The differential gear housing is segmented into a sealed outer periphery portion and an internal gear chamber. The sealed outer periphery maintains lubricant containment while the internal chamber allows controlled lubricant flow paths to reach all gear surfaces, including planetary gears and pinions, ensuring adequate lubrication without full immersion
Solution Approach 2:
A lubricant circulation system acts as an intermediary between the sealed lubricant reservoir and the gear surfaces. The system includes lubricant inlet passages that deliver lubricant to gear bearing surfaces, lubricant outlets that remove heated lubricant, and a lubricant pump that circulates the lubricant through the differential gear assembly, ensuring continuous lubrication and cooling without requiring full gear immersion
2Quantity of substance
If a controlled seal is used to maintain lubricant in the differential gear housing, then lubricant containment is improved, but fluid flow for lubrication becomes constrained
Solution Approach 1:
The lubricant circulation system is nested within the sealed differential gear housing. The lubricant pump, inlet passages, outlet passages, and flow control mechanisms are all contained within the sealed housing, allowing the system to maintain lubricant containment while providing internal fluid flow paths that deliver lubricant to all necessary gear surfaces
Solution Approach 2:
A hydraulic lubricant circulation system is implemented within the sealed housing. The lubricant pump creates hydraulic flow that forces lubricant through controlled passages to specific gear surfaces, while pressure control mechanisms regulate the flow rate and distribution, ensuring adequate lubrication delivery without compromising the sealed containment
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
The solution effectively minimizes windage losses while maintaining sufficient lubrication and cooling for the gear set, enhancing the efficiency and effectiveness of the axle assembly under heavy-duty off-road conditions.
Implementation Method 1
A source of selective fluid pressure is fluidly connected to the differential lock mechanism and provides high and low pressure levels to selectively lock the differential gear housing and one of the gears
Implementation Method 2
The differential gear housing has a bleed flow path to provide pressurized fluid flow into the differential gear housing irrespective of the pressure level
Implementation Method 3
the ability to cool and lubricate various components in the differential gear assembly is challenged
Data Source
Figure 1
Figure 2
AI summary
A differential axle assembly (20) for a work machine having a differential lock capability. The differential axle has a differential gear housing (46), which utilizes a sealed housing on the outside thereof and a bleed flow path (104) for pressurized liquid lubricant actuating a differential lock feature (70) to provide adequate cooling flow for the differential gear set (66, 68) and differential lock mechanism (70) under heavy duty circumstances.