Transfer Case Clutch Oil Distribution via Spool Valves
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Solution Overview
Problem
Existing transfer cases experience efficiency reduction due to continuous oil supply causing drag on the primary output shaft when the secondary output shaft is not driven, leading to friction and energy loss.
Innovation Solution
Incorporation of a clutch with a housing, interleaved plates, and spool valves that selectively release oil from the primary output shaft into the clutch housing only when needed, allowing for controlled lubrication and torque transfer between the primary and secondary output shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil is continuously supplied to the clutch, then the clutch is adequately lubricated and cooled, but drag and friction increase on the primary output shaft when the secondary output shaft is not driven
Solution Approach 1:
The patent implements a dynamic oil supply system where the clutch is lubricated only when needed (when engaged) rather than continuously. The oil supply mechanism is activated simultaneously with clutch engagement and deactivated when the clutch disengages, adapting the lubrication state to the operational state of the clutch.
Solution Approach 2:
The patent employs periodic oil supply to the clutch, where oil is delivered in cycles corresponding to clutch engagement periods. The oil supply is interrupted during disengagement periods, creating a periodic pattern of lubrication that matches the operational requirements and eliminates continuous drag.
2Reliability
If oil is continuously supplied to the clutch, then the clutch remains lubricated, but drag is created on the primary output shaft reducing vehicle efficiency
Solution Approach 1:
The oil supply system dynamically responds to clutch engagement status, activating oil flow only when the clutch is engaged and maintaining lubrication only during the periods when it is needed, thereby eliminating parasitic drag during disengagement and improving overall vehicle efficiency.
Solution Approach 2:
The patent extracts the harmful continuous oil supply from the system, removing the unnecessary lubrication that causes drag during clutch disengagement. Only the beneficial portion of oil supply (during engagement) is retained, eliminating the harmful effect while preserving the useful function.
3Loss of energy
If oil is selectively supplied to the clutch only when engaged, then energy loss is reduced, but the complexity of the oil distribution system increases
Solution Approach 1:
The patent combines the oil supply control function with the existing clutch actuation mechanism. The same system that controls clutch engagement also controls oil supply, merging two functions into one integrated system and avoiding the need for a completely separate complex control system.
Solution Approach 2:
The oil supply mechanism serves multiple functions: it lubricates the clutch during engagement, cools the clutch plates, and acts as a sealant. By making the oil supply system multi-functional, the patent reduces the need for additional separate systems, thereby limiting the increase in overall system complexity.
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 enhances vehicle efficiency by minimizing energy loss through controlled oil supply, reducing friction when the secondary output shaft is not engaged, and optimizing torque transfer.
Implementation Method 1
Each valve has a bore formed in the hub and a valve rod movable by the apply plate to open the valve... oil to flow through the valve in a radial direction
Implementation Method 2
The apply plate is configured to compress the plurality of interleaved plates for transferring torque between the hub and the housing
Implementation Method 3
Oil may be provided to the clutch, for example, to cool the clutch that engages the secondary output shaft
Data Source
AI summary
A transfer case comprises a primary output shaft, a secondary output shaft, a clutch, and a plurality of valves. The primary output shaft includes a hub rotationally coupled thereto. The clutch selectively couples the primary output shaft to the secondary output shaft to transfer torque therebetween. The clutch includes a housing, interleaved plates, and an apply plate. The housing is rotationally coupled to the secondary output shaft. The interleaved plates alternate between a first subset of the interleaved plates rotationally coupled to the hub and a second subset of the interleaved plates rotationally coupled to the housing. The apply plate compresses the interleaved plates for transferring torque between the hub and the housing. The valves selectively release oil supplied through the primary output shaft into the housing. Each valve includes a bore formed in the hub and a valve rod movable by the apply plate to open the valve.