Starter Torque Limiter Friction Disc for Compact High Torque
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Solution Overview
Problem
Existing torque limiters for motorcycles are limited in torque capacity due to compact size requirements and unstable torque settings, making it difficult to incorporate a larger torque capacity into power transmission mechanisms without increasing size or compromising stability.
Innovation Solution
A torque limiter design featuring a driven gear and transmission gear coaxially disposed with a circular disc-shaped friction member, where the friction member has a larger outer diameter than the driven gear, providing a larger friction area and allowing for increased torque capacity while maintaining a compact structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the outer diameter of friction plates is reduced to make the torque limiter compact, then the size is reduced, but the friction area decreases and torque capacity is limited
Solution Approach 1:
The patent transitions from a conventional friction plate structure to a friction member with an outer diameter larger than the driven gear, utilizing the radial dimension more effectively. This dimensional change allows the friction member to extend beyond the driven gear's outer diameter, increasing the friction area and torque capacity while maintaining a compact axial profile.
Solution Approach 2:
The friction member is designed to be nested within the space defined by the housing and driven gear arrangement, with its outer diameter extending beyond the driven gear but still fitting within the overall compact structure. This nesting approach maximizes the use of available radial space without increasing the axial width.
2Force
If multiple friction plates are stacked to increase torque capacity, then the torque capacity increases, but the axial width increases and it becomes difficult to incorporate into compact mechanisms
Solution Approach 1:
Instead of increasing torque capacity by stacking multiple friction plates in the axial direction (increasing width), the patent increases the outer diameter of the friction member in the radial direction. This dimensional shift allows for greater friction area and torque capacity without increasing the axial width, making it suitable for compact mechanisms.
3Volume of moving object
If a press-in type torque limiter is used to achieve compact structure, then the size is reduced, but the torque capacity becomes unstable due to press-fit interference and galling
Solution Approach 1:
The patent introduces a friction member as an intermediary element between the driven gear and the housing, which is axially movably fitted rather than press-fitted. This intermediary approach eliminates the need for press-fit interference and Corbett process, providing stable and reliable torque capacity while maintaining a compact structure.
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 design enables easy incorporation into power transmission mechanisms, providing a larger torque capacity and preventing excessive load on the starter motor, while maintaining a compact and stable structure.
Implementation Method 1
The driven gear and the transmission gear are configured to transmit power therebetween via a friction member
Data Source
AI summary
A torque limiter that enables setting a larger torque capacity although being compact and easy to incorporate into a power transmission mechanism, is provided. A torque limiter is incorporated into a power transmission mechanism for transmitting power from a starter motor to a crankshaft of an internal combustion engine. The torque limiter includes a driven gear for receiving power from the starter motor and a transmission gear for transmitting power. The driven gear and the transmission gear are coaxially disposed in a relatively rotatable manner. The driven gear and the transmission gear are configured to transmit power therebetween via a friction member. The friction member has a circular disc shape with an outer diameter that is larger than an outer diameter of the driven gear.