Reverse Rotation Prevention Mechanism for Motor Reducers
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Solution Overview
Problem
Conventional motor systems with reducers for power windows and sunroofs face challenges in preventing reverse rotation due to external forces, leading to instability and reduced transmission torque efficiency.
Innovation Solution
A reverse rotation prevention mechanism is implemented on the torque transmission path between the output shaft and driving shaft, utilizing two distinct frictional force generation units to inhibit and prevent reverse rotation, with the first unit preventing relative rotation and the second unit generating a braking force, optimized for stability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single frictional force generation unit is used to prevent reverse rotation, then the structure is simple, but the anti-reverse-rotation performance is unstable and transmission torque is lost due to sliding friction
Solution Approach 1:
The frictional force generation mechanism is divided into two distinct units: a first frictional force generation unit that prevents relative rotation during normal operation, and a second frictional force generation unit that generates braking force during reverse rotation. This segmentation allows each unit to specialize in specific functions, improving overall reliability while managing complexity through functional separation.
Solution Approach 2:
Different frictional force generation units are provided in different areas of the mechanism, with each area optimized for its specific function. The first unit operates during normal rotation with controlled friction, while the second unit activates during reverse rotation with higher braking friction. This local differentiation resolves the contradiction by providing stable anti-reverse performance without requiring the entire mechanism to be overly complex.
2Reliability
If the lock plate slides over the facing member to generate frictional force, then reverse rotation is prevented, but transmission torque is lost and abrasion occurs reducing life
Solution Approach 1:
The mechanism dynamically switches between different frictional force generation modes based on rotation direction. During normal forward rotation, the first frictional force generation unit operates with minimal sliding to maintain transmission efficiency. When reverse rotation is detected, the second frictional force generation unit activates to provide strong braking force. This dynamic operation reduces energy loss during normal operation while maintaining reliable reverse rotation prevention.
Solution Approach 2:
The harmful sliding friction that causes torque loss and abrasion is extracted and isolated into specific controlled areas. The first frictional force generation unit minimizes sliding contact during normal operation, while the second unit concentrates frictional braking action only when reverse rotation occurs. This extraction separates the useful reverse rotation prevention function from the harmful continuous sliding friction.
3Reliability
If a wave washer presses the lock plate toward the facing member, then reverse rotation is prevented, but the lock plate slides over the facing member producing frictional loss
Solution Approach 1:
The pressing mechanism is segmented into two functional areas: the first frictional force generation unit where controlled pressing occurs during normal operation, and the second frictional force generation unit where strong pressing provides braking during reverse rotation. This segmentation allows the wave washer to provide necessary pressing force for reverse rotation prevention while minimizing sliding friction during normal high-productivity operation.
Solution Approach 2:
The frictional characteristics are changed based on operational state. During normal operation, the first unit maintains parameters that allow efficient torque transmission with minimal friction. During reverse rotation, the second unit changes parameters to generate high frictional braking force. This parameter change resolves the contradiction between maintaining reverse rotation resistance and preserving transmission efficiency.
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 solution ensures stable anti-reverse-rotation performance by reducing frictional losses and extending the mechanism's lifespan, effectively preventing unintended motor rotation under external forces.
Implementation Method 1
a first frictional force generation unit configured to inhibit a braking rotational member provided on the torque transmission path from rotating relative to another member when an external force is exerted on the output shaft
Implementation Method 2
a second frictional force generation unit configured to generate a braking force that prevents reverse rotation when an external force is exerted on the output shaft, by causing a portion of the braking rotational member to be pressed
Data Source
AI summary
A reverse rotation prevention mechanism is provided on a torque transmission path between an output shaft and a driving shaft of a motor. The reverse rotation prevention mechanism includes: a first frictional force generation unit configured to inhibit a lock plate provided on the torque transmission path from rotating relative to another member when an external force is exerted on the output shaft; and a second frictional force generation unit configured to generate a braking force that prevents reverse rotation when an external force is exerted on the output shaft by causing a portion of the lock plate to be pressed. The first frictional force generation unit is provided in an area different from the second frictional force generation unit.