Torque limiter and drive device
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Solution Overview
Problem
Conventional torque limiters used in electrically powered toilet seat/lid opening and closing systems 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 design featuring a first rotary member, first and second friction members, and a second rotary member, where the friction members generate frictional force to transmit rotational force, and when an excess load exceeds the maximum static frictional force, the system slips to prevent torque transmission, thereby protecting motor and gear components without generating noise.
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 frequency of mechanical noise occurrences is reduced, but peripheral components such as motor and gear need to have sufficiently high strength and component costs increase
Solution Approach 1:
The patent replaces the ratchet-based mechanical torque limiter with a friction-based torque limiter. The friction members generate frictional force to transmit rotational force, and when excess load exceeds the maximum static frictional force, the system slips to prevent torque transmission. This substitution eliminates the mechanical noise generated by ratchet engagement/disengagement while allowing lower torque settings, thereby reducing component strength requirements and costs.
Solution Approach 2:
The patent changes the fundamental operating parameter from ratchet engagement torque to friction-based torque. By using friction members with controllable friction coefficients, the torque limiter can precisely control the torque threshold for slip occurrence. This parameter change allows optimization of the torque setting without being constrained by the discrete engagement characteristics of ratchets, enabling lower torque settings that reduce component strength requirements while maintaining noise suppression.
2Ease of manufacture
If a ratchet is made of resin to reduce cost, then manufacturing cost is reduced, but large variations are seen in torque at which transmission of excess loads is shut off and variations may become larger over time due to deformation
Solution Approach 1:
The patent replaces the ratchet mechanism with a friction-based system where torque transmission is controlled by frictional force between friction members. This substitution eliminates the deformation issues associated with resin ratchets because the friction members can be made from materials with stable friction coefficients. The torque limit is determined by the friction force rather than the mechanical strength and deformation characteristics of a ratchet, thereby improving torque limit consistency and reliability over time.
Solution Approach 2:
The patent employs friction members that can be made from composite materials or materials with stable friction properties. These materials maintain consistent friction coefficients under various operating conditions, ensuring reliable and consistent torque limiting performance. The use of such materials allows the torque limiter to maintain its specified torque threshold without the variations and drift experienced by resin ratchets.
3Reliability
If ratchet elements are used to protect components from excess load, then component protection is achieved, but rotation of the ratchet elements causes mechanical noise
Solution Approach 1:
The patent replaces the ratchet-based excess load protection mechanism with a friction-based torque limiter. The friction members generate frictional force to transmit rotational force under normal conditions, and when excess load exceeds the maximum static frictional force, the friction members slip to prevent torque transmission. This substitution provides the same component protection function as ratchets but eliminates the mechanical noise caused by ratchet element rotation and engagement/disengagement.
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, ensures silent operation, 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
when an excess load exceeds the maximum static frictional force, the system slips to prevent torque transmission
Data Source
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.