Transfer Case Planetary Gear Clutch Collar Actuation
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Solution Overview
Problem
Current transfer cases for vehicles lack an efficient mechanism to seamlessly switch between low and high speed gear ratios, affecting vehicle performance and fuel efficiency.
Innovation Solution
A transfer case design incorporating a planetary gear set, a moveable clutch collar, and an actuator that selectively engages and disengages the sun gear and planet gear carrier based on gear ratios, utilizing pressurized fluid to actuate the clutch collar between discrete positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional transfer case design is used, then the structure is simple, but the gear ratio switching is not efficient and affects vehicle performance
Solution Approach 1:
The clutch collar is designed to be moveable along the input shaft, allowing dynamic repositioning between low speed range (engaging planet gear carrier) and high speed range (engaging sun gear). This dynamic mechanism enables efficient gear ratio switching while maintaining a relatively compact structure.
Solution Approach 2:
The clutch collar acts as an intermediary component that selectively couples the planetary gear set to the input shaft. By engaging different elements (planet gear carrier or sun gear) through this intermediary, the system achieves smooth gear ratio transitions without direct complex mechanical linkages.
2Reliability
If a planetary gear set with selective engagement is used, then smooth gear ratio transition is achieved, but the mechanism complexity increases
Solution Approach 1:
The clutch collar combines multiple engagement features (face gear on one end, spline on the other) into a single component that can selectively couple to different planetary gear elements. This merging approach achieves smooth gear transitions while reducing the number of separate components needed.
Solution Approach 2:
The actuator uses pressurized fluid (pneumatic or hydraulic) to move the clutch collar between engagement positions. This provides controlled, smooth transitions between gear ratios without complex mechanical linkages or manual intervention.
3Loss of time
If manual gear shifting is used, then the structure is simple, but the response time and precision are insufficient
Solution Approach 1:
The patent replaces manual mechanical shifting with an automated actuator system that uses pressurized fluid to move the clutch collar. This substitution reduces response time and improves precision while maintaining a relatively simple overall structure.
Solution Approach 2:
The actuator system automatically positions the clutch collar based on vehicle operating conditions, eliminating the need for manual intervention. The system self-regulates gear ratio selection to optimize vehicle performance and fuel efficiency.
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
Enables smooth transition between low and high speed gear ratios, enhancing vehicle performance and fuel efficiency by optimizing torque transfer and gear engagement.
Implementation Method 1
The actuator may include a first piston, a second piston, and an actuator shaft. Pressurized fluid may be provided to the first cavity via the first port to actuate the clutch collar to the first position. Pressurized fluid may be provided to the second cavity via the second and third ports to actuate the clutch collar to the second position.
Data Source
AI summary
A transfer case having a planetary gear set, a clutch collar, and an actuator. The actuator is configured to actuate the clutch collar between a low speed range position in which the clutch collar engages a planet gear carrier of the planetary gear set, and a high speed range position in which the clutch collar engages a sun gear of the planetary gear set.