Clutch Receiving Member Clearance for Faster Engagement Response
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Solution Overview
Problem
Existing power transmission devices experience increased sliding resistance due to centrifugal forces at high speeds, leading to dull clutch engagement responsiveness and unpleasant operability sensations for drivers.
Innovation Solution
Incorporation of a radially-outside restricting portion that restricts the movement of the receiving member relative to the pressure member, maintaining clearance between the receiving and clutch members, and utilizing a back-torque limiting cam to reduce press-contact force when the output member's rotation speed exceeds the input member's speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiving member is pressed against the clutch member by centrifugal force at high rotation speeds, then the back-torque limiting cam function is maintained, but the sliding resistance of the receiving member becomes excessively large
Solution Approach 1:
A radially-outside restricting portion is introduced as an intermediary element between the receiving member and clutch member. This restricting portion prevents direct contact and sliding between the receiving member's outer peripheral surface and the clutch member's inner peripheral surface, thereby eliminating excessive sliding resistance while maintaining the back-torque limiting function through the cam surfaces.
2Force
If the receiving member contacts the clutch member radially outwardly, then the back-torque limiting cam reduces press-contact force, but the sliding resistance increases causing dull clutch engagement
Solution Approach 1:
The radially-outside restricting portion extracts or removes the harmful sliding contact between the receiving member and clutch member. By preventing this contact, the restricting portion eliminates the source of excessive sliding resistance that causes dull clutch engagement, while preserving the necessary back-torque limiting force reduction function.
3Reliability
If clearance is not maintained between the receiving member and clutch member, then the back-torque limiting cam surfaces can engage, but sliding resistance increases and operability deteriorates
Solution Approach 1:
The radially-outside restricting portion creates a localized clearance condition between the receiving member and clutch member. This local quality change ensures that the cam surfaces can still engage axially to provide back-torque limiting function, while preventing radial sliding contact that would cause excessive friction and poor operability.
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 configuration reduces sliding resistance, enhancing clutch engagement responsiveness and operability by maintaining the necessary clearance and stabilizing the contact between the receiving and clutch members.
Implementation Method 1
when the entire device including the pressure member and the clutch member rotates at a high speed, the receiving member is pressed against the clutch member, which is positioned radially outside, by a generated centrifugal force
Data Source
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AI summary
Provided is a power transmission device that can improve responsiveness when engaging a clutch and improve operability by reducing the sliding resistance of a receiving member. The power transmission device includes: a pressure member 5 that is capable pressing drive-side clutch plates and driven-side clutch plates against each other or releasing a press-contact force; a clutch spring 10 that urges the pressure member in a direction such that the clutch plates are pressed against each other; a receiving member 11 that is constituted by a separate member attached to the pressure member 5; and a back-torque limiting cam that reduces the press-contact force between the clutch plates when the rotation speed of an output member exceeds the rotation speed of an input member. The power transmission device includes a radially-outside restricting portion that is capable of restricting radially-outward movement of the receiving member 11 relative to the pressure member 5 and is capable of maintaining a clearance t between a side surface 11d of the receiving member 11 and an inner peripheral wall 4e of a clutch member 4.