Electric Parking Brake Cable Twist Alignment for Quiet Release
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Solution Overview
Problem
The existing electric parking brake device generates a slapping sound and increased wear due to the clearance between the projection portion and groove in the rotation restricting means, leading to high sliding resistance and operating noise during switching between parking brake states.
Innovation Solution
The device incorporates a brake cable formed by twisting wires, with the twisting force acting in the same direction as the nut's rotational direction, and uses rotation restricting projection portions on the screw shaft and grooves in the actuator case to minimize collisions and sliding resistance, reducing operating noise and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rotation restricting means with projection portion and groove is used to restrict screw shaft rotation, then rotational motion is restricted, but clearance between projection portion and groove causes slapping sound and increased wear during rotational direction changes
Solution Approach 1:
A rotation restricting plate is introduced as an intermediary component between the screw shaft and actuator case. The plate includes rotation restricting protrusions that engage with grooves, mediating the rotational restriction function while reducing direct contact and collision between the screw shaft projection portions and the actuator case grooves, thereby suppressing slapping sounds and wear
Solution Approach 2:
The rotation restricting plate is designed to engage with the screw shaft before significant rotational deviation occurs. The protrusion-groove engagement on the plate provides preliminary rotational constraint, cushioning against unintended rotation and preventing the screw shaft projection portions from colliding with the actuator case grooves
2Stability of the object's composition
If projection portion is pressed strongly against groove side surface during axial movement, then rotational motion is effectively restricted, but sliding resistance increases causing high wear
Solution Approach 1:
The rotation restricting plate serves as a mediator that bears the sliding contact between the screw shaft and the actuator case. The protrusions on the plate engage with grooves to provide rotational restriction while reducing direct sliding contact, thereby lowering sliding resistance and wear on critical components
Solution Approach 2:
The design changes the contact parameters by introducing the rotation restricting plate with optimized protrusion geometry and groove configuration. This alters the friction and wear characteristics of the rotation restricting interface, reducing sliding resistance while maintaining rotational constraint 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
This design effectively suppresses slapping sounds and reduces wear by aligning the twisting force with the nut's rotation, minimizing collisions and sliding resistance, thereby enhancing the operational silence and longevity of the brake device.
Implementation Method 1
the brake cable is formed by twisting a plurality of wires so as to generate a twisting force in a fixed direction when the brake cable is pulled
Data Source
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AI summary
In an electric parking brake device configured in such a way that a parking brake state resulting from pulling of a brake cable is released by loosening the brake cable, the brake cable (37) is formed by twisting together a plurality of wires (92) in such a way as to generate a twisting force in a fixed direction when pulled, and the direction in which the twisting force generated by the brake cable (37) in a pulled state acts on a screw shaft (38) is set to be the same direction as the direction in which a nut (61) is rotated to loosen the brake cable (37). This makes it possible to reduce an operating sound and to reduce wear of members constituting a rotation restricting means.