Transfer Case Lubrication via Relief Valve Trough
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Solution Overview
Problem
In vehicle drivetrain systems, stopping the rotation of the sprocket and chain in two-wheel drive mode to increase fuel efficiency disrupts lubrication of components like the clutch assembly and bearing assembly, necessitating an alternative lubrication source.
Innovation Solution
A lubrication system that includes a pump to supply working fluid to a fluid reservoir for an actuator, a relief valve to manage pressure, and a trough to direct fluid to the bearing assembly when the clutch is disengaged, ensuring continuous lubrication of the transfer case components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the sprocket and chain rotation is stopped to increase fuel efficiency in two-wheel drive mode, then fuel economy is improved, but lubrication of the clutch assembly and bearing assembly is disrupted
Solution Approach 1:
The lubrication system is segmented into multiple independent pathways: one for the clutch assembly and another for the bearing assembly. This allows lubrication to be maintained to specific components even when the main chain rotation stops, resolving the contradiction by dividing the lubrication function into separable segments that can operate independently.
Solution Approach 2:
A trough is introduced as an intermediary component to deliver lubricant from the fluid reservoir to the bearing assembly when the clutch is disengaged. This intermediary structure enables lubrication to continue through an alternative path, maintaining reliability while allowing the chain to remain stationary for fuel efficiency.
2Productivity
If the chain rotation is stopped to disconnect the primary and secondary output shafts, then power transfer is optimized for two-wheel drive mode, but the clutch assembly and bearing assembly lose their lubrication source
Solution Approach 1:
The system stores lubricant in advance in a fluid reservoir that is pre-filled and positioned to supply lubrication when needed. This preliminary preparation ensures that lubrication is immediately available when the clutch disengages and the chain stops rotating, preventing component wear before it can occur.
Solution Approach 2:
The pump system is designed to automatically pump lubricant from the reservoir to the bearing assembly when the clutch is in the disengaged position, without requiring external intervention or continuous chain rotation. This self-service mechanism ensures lubrication is maintained autonomously, protecting components from wear while optimizing power transfer.
3Reliability
If a pump system is added to provide alternative lubrication when the clutch is disengaged, then component protection is improved, but system complexity increases
Solution Approach 1:
The pump system is designed to serve multiple functions: it can lubricate the clutch assembly when the chain is rotating, and it can lubricate the bearing assembly when the clutch is disengaged. This multi-functionality reduces the need for separate dedicated systems, maintaining reliability while minimizing the increase in overall system complexity.
Solution Approach 2:
The system uses hydraulic principles with a pump and fluid reservoir to deliver lubricant through controlled pathways. This approach provides precise control over lubricant delivery to different components based on clutch position, achieving reliable continuous lubrication through a relatively compact and manageable hydraulic system rather than more complex mechanical arrangements.
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 maintains efficient operation and improves fuel economy by ensuring consistent lubrication of the transfer case components even when the clutch is in a disengaged position, preventing wear and tear.
Implementation Method 1
a pump configured to selectively supply a working fluid to a fluid reservoir of an actuator
Implementation Method 2
The relief valve inlet opens to receive the working fluid based on a threshold pressure level of the working fluid in the fluid reservoir
Implementation Method 3
The trough is configured to carry the working fluid from the relief valve outlet to a bearing assembly
Data Source
AI summary
A lubrication system (400) for a transfer case (200) includes a pump (228) selectively supplying a working fluid to a fluid reservoir of an actuator (226) configured to apply force to a clutch assembly (214) to cause the clutch assembly (214) to move between a disengaged position and an engaged position. The lubrication system also includes a relief valve (302) having a relief valve inlet fluidly coupled to the fluid reservoir of the actuator (226) which opens to receive the working fluid based on a threshold pressure level of the working fluid in the fluid reservoir. The lubrication system also includes a trough (306) fluidly coupled to a relief valve outlet of the relief valve (302). The trough (306) carries the working fluid from the relief valve outlet to a bearing assembly (227) associated with at least one of an input shaft (204) and a primary output shaft (206) of the transfer case (200) when the clutch assembly (214) is in the disengaged position.