Bidirectional Torque Limiter With Asymmetric Slip Torque
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Solution Overview
Problem
Existing bidirectional torque limiters set the same slip torque for both directions of rotation, making it difficult to achieve a smaller slip torque when inputting rotation from the driving part compared to the driven part.
Innovation Solution
The bidirectional torque limiter is designed with an external coil spring that clamps the outer race with a relatively small force and an internal coil spring that clamps the inner race with a larger force, allowing the external coil spring to slip when a rotation torque is applied from the driving part and the internal coil spring to slip when a torque is applied from the driven part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coil spring is used to clamp the race in both directions, then the structure is simple, but the slip torque is the same in both rotation directions
Solution Approach 1:
The single coil spring is segmented into two separate coil springs (first and second coil springs) that clamp the outer race from opposite directions. This segmentation allows each spring to have different clamping forces, thereby achieving different slip torques in different rotation directions while maintaining a relatively simple overall structure.
Solution Approach 2:
Different local qualities are applied to the two coil springs by setting their clamping forces differently. The first coil spring has a smaller clamping force while the second has a larger clamping force, creating asymmetric local properties that enable different slip torques in different directions.
2Device complexity
If both coil springs have the same clamping force, then the design is symmetric and simple, but it cannot achieve smaller slip torque when inputting rotation from the driving part
Solution Approach 1:
The design transitions from symmetric to asymmetric by setting different clamping forces for the two coil springs. The first coil spring has a smaller clamping force while the second has a larger clamping force, enabling the torque limiter to provide different slip torques depending on the direction of rotation, which is essential for distinguishing between driving part input and driven part input.
Solution Approach 2:
Different local qualities are introduced by making the clamping forces of the two coil springs unequal. This allows the system to have different friction characteristics in different directions, enabling the driving part to have a smaller slip torque while the driven part has a larger slip torque.
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 allows for a smaller slip torque when rotation is input from the driving part compared to when it is input from the driven part, enhancing the torque limiter's ability to manage and transmit rotational forces effectively.
Implementation Method 1
an external coil spring is mounted on the outer peripheral surface of the outer race, the external coil spring in a free state has an inner diameter smaller than the outer diameter of the outer race, and the external coil spring clamps the outer race with a relatively small clamping force
Implementation Method 2
an internal coil spring is mounted on the outer peripheral surface of the inner race, the internal coil spring in a free state has an inner diameter smaller than the outer diameter of the inner race, and the internal coil spring clamps the inner race with a relatively large clamping force
Implementation Method 3
in a case where the rotation torque is smaller than a first predetermined torque, the auxiliary member and the housing rotate integrally, namely, the rotation torque is transmitted
Data Source
AI summary
A bidirectional torque limier, which allows setting a slip torque for a case of inputting rotation from a driving part to be smaller than a slip torque for a case of inputting rotation from a driven part. The force of an external coil spring (42) to clamp an outer race (8) is set smaller than the force of an internal coil spring (48) to clamp an inner race (10), so that the external coil spring (42) increases its diameter to slip with respect to the outer race (8) when a rotation torque is applied from the driving part, while the internal coil spring (48) increases its diameter to slip with respect to the inner race (10) when a rotation torque is applied from the driven part.