Friction-Based Torque Limiter to Reduce Noise and Component Cost
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Solution Overview
Problem
Conventional torque limiters for toilet seats and other movable objects suffer from mechanical noise and increased component costs due to high torque settings, and exhibit torque variations over time due to deformation, especially when handling excess loads.
Innovation Solution
A torque limiter using a first and second rotary member with friction members, where the friction members are stacked and housed in a housing part, and an elastic member biases them to control frictional force, preventing excess load transmission by slipping when the load exceeds the maximum static frictional force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the certain torque is set relatively high to suppress mechanical noise frequencies, then the occurrence frequency of mechanical noise is reduced, but the component costs increase due to the need for higher strength peripheral components
Solution Approach 1:
The patent replaces the conventional ratchet mechanism with a friction-based torque limiter. Instead of using mechanical ratchet teeth that engage and disengage, the invention uses friction members (first and second friction members) that generate frictional force to limit torque. This substitution eliminates the clicking noise inherent in ratchet mechanisms while allowing for lower torque settings, thereby reducing component costs without sacrificing noise suppression.
Solution Approach 2:
The patent changes the fundamental parameter of torque limitation from mechanical engagement (ratchet teeth) to friction-based force. By using friction members with controlled friction coefficients and applying biasing force through elastic members, the system achieves torque limitation without the high torque settings required by ratchet mechanisms. This parameter change allows for quieter operation and lower component specifications.
2Reliability
If the certain torque is set relatively high to protect components from excess load, then component protection is improved, but the component costs increase
Solution Approach 1:
The patent substitutes the ratchet-based mechanical protection system with a friction-based protection system. The friction members, when pressed together with controlled force through elastic members, provide torque limitation that protects components without requiring high-strength peripherals. The friction mechanism inherently limits the maximum torque transmitted, providing component protection at lower torque settings.
Solution Approach 2:
The patent changes the protection mechanism from high-torque mechanical engagement to controlled friction force. By adjusting friction coefficients, contact area, and biasing force, the system achieves adequate component protection at lower torque levels, reducing the strength requirements and costs of peripheral components while maintaining reliability.
3Ease of manufacture
If a ratchet is made of resin to reduce cost, then manufacturing cost is reduced, but large variations are seen in limit torque and variations increase over time due to deformation
Solution Approach 1:
The patent replaces the ratchet tooth engagement mechanism with a friction-based torque limitation system. This substitution eliminates the problem of resin deformation affecting limit torque, as friction force can be more consistently controlled through material selection, surface treatment, and pressing force management. The friction mechanism is less sensitive to dimensional variations and deformation compared to precision mechanical engagement.
Solution Approach 2:
The patent changes from a geometry-dependent torque limitation (ratchet tooth pitch and engagement) to a force-dependent mechanism (friction force). Friction force can be more reliably controlled through material properties, surface conditions, and applied pressure, reducing variations in limit torque even when made from resin materials. This parameter change improves torque consistency while maintaining cost-effectiveness.
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 effectively suppresses the influence of excess loads on components, operates silently, and reduces component costs by allowing lower torque settings without mechanical noise, while maintaining reliability and minimizing torque variations over time.
Implementation Method 1
at least one second friction member arranged so as to overlap the first friction member, and configured to rotate with rotation of the first rotary member by using frictional force generated between the second friction member and the first friction member
Implementation Method 2
an elastic member attached to the rotary shaft and a tightener attached to the rotary shaft, wherein the elastic member biases the first rotary member and the second rotary member in an identical direction
Data Source
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AI summary
A torque limiter includes: a first rotary member configured to be rotated by a drive source; at least one first friction member engaged with the first rotary member; at least one second friction member arranged so as to overlap the first friction member, and configured to rotate with rotation of the first rotary member by using frictional force generated between the second friction member and the first friction member; and a second rotary member engaged with the second friction member. It is preferable that the first rotary member and the second rotary member be pivotally supported by an identical rotary shaft, and that, while either the first rotary member and the second rotary member is fixed to the rotary shaft, the other one be supported so as to be rotatable about the rotary shaft.