Segmented Transfer Case Hydraulic Clutch Integration
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Solution Overview
Problem
Existing two-speed transfer cases in vehicles with automatic transmissions face challenges due to lubrication complexity, requiring separate oil levels and complex return pump systems, leading to increased manufacturing costs without significant benefits.
Innovation Solution
A segmented transfer case design that utilizes hydraulic fluid from the automatic transmission to operate the clutch, eliminating the need for a return pump by integrating the hydraulic clutch within the same lube environment as the automatic transmission, allowing for smoother and more precise control of two-wheel and four-wheel drive modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a return pump and complex hydraulic routing are used to regulate oil levels between transfer case and automatic transmission, then lubrication control is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the transfer case hydraulic system with the automatic transmission hydraulic system by positioning the transfer case clutch assembly within the transmission oil pan. This integration eliminates the need for separate return pumps and complex hydraulic routing, as the transmission pump and valve body directly control both transmission and transfer case functions through a unified hydraulic system.
Solution Approach 2:
The automatic transmission pump and valve body are made multi-functional by enabling them to control both automatic transmission operations and transfer case clutch engagement. The transmission hydraulic system serves dual purposes: lubricating transmission components and actuating transfer case shifting elements, thereby eliminating dedicated return pump hardware.
2Reliability
If separate oil levels are maintained for transfer case and automatic transmission, then lubrication requirements are met, but device complexity increases
Solution Approach 1:
The patent combines the transfer case operating fluid with the automatic transmission fluid by positioning the clutch assembly within the transmission oil pan. This allows both systems to share a common fluid reservoir and lubrication source, eliminating the need for separate oil level management and return pump systems while meeting the lubrication requirements of both transmission and transfer case components.
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 configuration simplifies the transfer case design, reduces manufacturing costs, and enhances control precision for shifting and drive modes, while maintaining efficient fluid management within the automatic transmission system.
Implementation Method 1
The automatic transmission has available hydraulic pressure that has not previously been used to perform transfer case functions
Implementation Method 2
A friction material is bonded to a clutch hub and extends around substantially one-half of the clutch hub
Data Source
AI summary
A two-speed segmented transfer case includes an automatic transmission side, and a transfer case side. The transfer case side having a gear reduction set, and a shift sleeve for selecting between the high, or direct drive speed, and the low, or reduced gear speed. The transmission side includes a hydraulic clutch which is used to transfer power from the transmission, to the front wheels. The hydraulic clutch is operated and controlled by the use of automatic transmission fluid that comes from the vehicle transmission. When fully engaged, the hydraulic clutch causes the power coming into the transfer case to be split between the front and rear wheels. This configuration allows for the elimination of a separate actuation system that would normally control the engagement of the clutch.