Transfer Case Hub Oil Distribution Mechanism
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Solution Overview
Problem
In vehicle drivetrain components, the continuous supply of oil to the clutch in transfer cases can create drag or friction on the primary output shaft when the secondary output shaft is not driven, reducing vehicle efficiency.
Innovation Solution
A transfer case design featuring a hub with an outer and inner annular member, where the inner annular member is rotatable within the outer annular member to selectively release oil into the clutch when engaged and prevent oil release when disengaged, using a spring to bias the inner member into a closed valve position by default.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oil is continuously supplied to the clutch, then the clutch is cooled when engaged, but drag or friction is created on the primary output shaft when disengaged
Solution Approach 1:
The hub assembly is designed with an inner annular member that can rotate relative to the outer annular member, dynamically changing the oil flow path from closed to open state based on clutch engagement status. This dynamic adjustment eliminates continuous oil supply when the clutch is disengaged, reducing drag while maintaining cooling capability when engaged.
Solution Approach 2:
The system uses the rotational motion of the primary output shaft itself to drive the inner annular member and control the oil flow. The rotation of the primary output shaft automatically opens the oil flow path when the clutch is engaged, eliminating the need for external control mechanisms while achieving self-regulated oil distribution.
2Reliability
If oil is continuously supplied to the clutch, then the clutch remains lubricated, but friction is created due to shearing of oil between plates when the secondary output shaft is not driven
Solution Approach 1:
The oil supply to the clutch is made periodic rather than continuous. The hub assembly rotates to periodically open and close the oil flow path, supplying oil only during the periods when the clutch is engaged and requiring lubrication, while closing the path during disengagement to eliminate harmful friction from continuous oil presence.
Solution Approach 2:
The static oil supply system is transformed into a dynamic one where the inner annular member rotates to control oil flow timing. This dynamic control ensures oil is supplied only when the clutch plates are engaged and moving, preventing oil shearing friction when the clutch is disengaged while maintaining reliable lubrication during operation.
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 minimizes oil-related drag on the primary output shaft by ensuring oil is only supplied to the clutch when needed, enhancing vehicle efficiency by reducing friction and drag when the secondary output shaft is not driven.
Implementation Method 1
The spring is coupled to the outer annular member and the inner annular member, and normally biases the inner annular member into the first position
Implementation Method 2
The inner annular member is rotatable within the outer annular member for the hub to selectively release oil into the clutch
Implementation Method 3
The hub forms a closed valve when the inner annular member is in the first position
Implementation Method 4
The hub forms an open valve when the inner annular member is in the second position
Data Source
AI summary
A transfer case includes a primary output shaft, a secondary output shaft, a clutch, and a hub. The clutch includes a plurality of interleaved plates for selectively rotationally coupling the primary output shaft to the secondary output shaft. The hub rotationally couples the primary output shaft and the clutch. The hub includes an outer annular member and an inner annular member. The inner annular member is rotatable within the outer annular member for the hub to selectively release oil into the clutch.