Transaxle Torque Limiter for Power Train Overload Protection
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Solution Overview
Problem
Conventional four-wheel driving vehicles, such as utility vehicles, face challenges in managing power train overload during undulating terrain travel, particularly when the front wheels land before the rear wheels, leading to stress on the power train due to sudden load application, and existing solutions are complex and costly.
Innovation Solution
The implementation of a transaxle system with a torque limiter and clutch shifter mechanism that automatically adjusts the drive mode from four-wheel drive to two-wheel drive when excessive load is detected, using a simple mechanical force-based system to protect the power train from overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a driving mode selection clutch is provided on the input shaft to manually switch between 4WD and 2WD modes, then the driver can select the appropriate drive mode, but it is difficult for the driver to make instant decisions and operations to disengage the clutch each time the UTV jumps
Solution Approach 1:
The torque limiter automatically detects excessive torque conditions and disengages the clutch without driver intervention. The system serves itself by using the excessive torque as the triggering mechanism to activate the disengagement, eliminating the need for manual operation during critical moments
Solution Approach 2:
The torque limiter creates a feedback loop where the torque transmitted through the power train is continuously monitored. When torque exceeds the limiting value, the system responds by disengaging the clutch, providing automatic protection based on real-time torque conditions
2Reliability
If an electronic control system with actuator is equipped to automatically control clutch switching based on jumping and landing detection, then automatic power train protection is achieved, but the system becomes complicated and expensive
Solution Approach 1:
The patent replaces complex electronic control systems and actuators with a purely mechanical torque limiter mechanism. The torque limiter uses mechanical forces and torque transmission principles to automatically disengage the clutch when excessive torque is detected, eliminating the need for sensors, electronic controllers, and electric actuators
Solution Approach 2:
The torque limiter uses a simple mechanical design with basic components that can be manufactured at low cost. The mechanism relies on straightforward mechanical elements rather than expensive electronic subsystems, making the solution economically viable
3Device complexity
If the torque limiter is designed with simple mechanical force-based system, then the system complexity and cost are reduced, but the effectiveness of automatic clutch disengagement must be maintained
Solution Approach 1:
The torque limiter extracts only the essential function of torque monitoring and clutch disengagement from the complex electronic control system. By isolating and implementing just the torque limiting function through simple mechanical means, the patent achieves reliability without complexity
Solution Approach 2:
The torque limiter acts as a mechanical intermediary between the power train and the clutch. It mediates the torque transmission by automatically interrupting it when excessive torque occurs, serving as a simple but effective bridge that protects the power train without requiring complex control systems
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 effectively reduces power train stress by automatically shifting to two-wheel drive when excessive load is applied, protecting the engine and rear transaxle from overload and maintaining system performance over time by preventing contamination and rust.
Implementation Method 1
The torque limiter is configured such that the first and second sleeves are layered in a radial direction of the first and second input shafts and contact and press each other with a radial surface pressure therebetween to limit a torque transmitted between the first and second sleeves to a limiting value.
Data Source
AI summary
A transaxle comprises first and second input shafts coaxial to each other, an output shaft drivingly connected to the second input shaft, a torque limiter interposed between the first and second input shafts, and a housing incorporating the first and second input shafts, the output shaft and the torque limiter. The torque limiter includes first and second sleeves. The first sleeve is fitted to the first input shaft unrotatably relative to the first input shaft. The second sleeve is fitted to the second input shaft unrotatably relative to the second input shaft. The first and second sleeves are layered in a radial direction of the first and second input shafts so as to be pressed against each other with a radial surface pressure to limit a torque transmitted between the first and second sleeves to a limiting value.