Transfer Case Lubrication Receptacle for Churning Reduction
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Solution Overview
Problem
Existing transfer cases for four-wheel drive vehicles experience inefficiencies due to lubricant churning and foaming, especially in two-wheel drive mode, where the secondary shaft rotates without torque transfer, leading to increased load on the engine and reduced lubricant capacity.
Innovation Solution
A transfer case design with a lubricant collection receptacle located remotely from the sump, minimizing lubricant exposure to the secondary sprocket, and an actively or passively controlled lubricant system to manage lubricant distribution, reducing churning and foaming, and maximizing lubricant capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lubricant collection receptacle is located near the sump underneath the secondary shaft, then the lubricant can be easily accessed for lubrication, but more lubricant is exposed to the secondary sprocket causing increased churning and foaming
Solution Approach 1:
The lubricant collection receptacle is extracted from its conventional location near the sump and repositioned to a remote location within the transfer case housing. This separation removes the lubricant storage function from the churning zone, allowing the lubricant to be kept away from the secondary sprocket during high-speed two-wheel drive operation, thereby reducing churning losses and foaming while maintaining easy access through controlled fluid communication.
Solution Approach 2:
The system employs dynamic control of fluid communication between the lubricant collection receptacle and the sump area, allowing the lubricant level and position to change based on operating conditions. During high-speed two-wheel drive, the lubricant is held in the remote receptacle away from churning; during torque transfer operations, fluid communication is established to deliver lubricant where needed, optimizing performance across different operating modes.
2Reliability
If a lubricant pump is used to provide lubrication, then adequate lubrication can be ensured, but it generates a parasitic load on the vehicle engine
Solution Approach 1:
The transfer case lubrication system is designed to be self-servicing through passive lubricant delivery mechanisms. The lubricant collection receptacle positioned remotely from the sump allows lubricant to be delivered to the secondary shaft and sprocket area through gravity, pressure differential, or capillary action during operation, eliminating the need for an active pump and its associated parasitic engine load while maintaining reliable lubrication.
Solution Approach 2:
Instead of continuous pumping, the system utilizes periodic lubricant delivery where lubricant is supplied to the friction pack and shafts during clutch engagement and torque transfer events. The remote receptacle stores lubricant that is then delivered periodically when needed, rather than requiring continuous pump operation, thereby reducing energy consumption while ensuring adequate lubrication during critical operations.
3Quantity of substance
If more lubricant is stored in the transfer case, then lubrication capacity is improved, but the distance from the sprocket wheel to the bottom of the transfer case increases
Solution Approach 1:
Instead of increasing lubricant capacity by increasing the vertical height of the transfer case, the lubricant collection receptacle is positioned in a remote horizontal location within the existing housing volume. This utilizes unused space in the transfer case cavity, allowing increased lubricant storage capacity without increasing the overall height or distance from the sprocket wheel to the bottom of the case, thereby maintaining compact dimensions while improving lubrication capacity.
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 enhances lubricant efficiency by minimizing lubricant exposure to the secondary sprocket, reducing engine load, and preventing foaming, thereby improving the overall performance and efficiency of the transfer case.
Implementation Method 1
A transfer case design with a lubricant collection receptacle located remotely from the sump, minimizing lubricant exposure to the secondary sprocket
Data Source
AI summary
A transfer case is provided with a primary shaft which is selectively engagable with a secondary shaft via a clutch mechanism. The clutch mechanism is inclusive of a friction pack. A hub of the clutch mechanism is connected on the primary shaft and the clutch housing is torsionally fixed with a primary sprocket rotatively mounted on the primary shaft. A passive or active controlled lubricant collection receptacle is provided which maximize fluid retention in conditions wherein there is not a high demand of torque for the clutch system of the transfer case thereby minimizing fluid that is unnecessarily churned by engagement with the hub connected with the secondary shaft.