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, 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: an external coil spring for clamping the outer race and an internal coil spring for clamping the inner race. This segmentation allows each spring to be independently configured with different clamping forces, enabling different slip torques in different rotation directions while maintaining structural simplicity
Solution Approach 2:
Different clamping forces are applied at different locations: the external coil spring applies a first clamping force to the outer race, while the internal coil spring applies a second clamping force to the inner race. This local differentiation of clamping forces enables the torque limiter to have different slip characteristics in different rotation directions
2Reliability
If the external coil spring clamping force is increased, then the slip torque from driving part is increased, but it becomes larger than desired for efficient operation
Solution Approach 1:
The clamping force parameter of the external coil spring is specifically adjusted to be relatively small compared to the internal coil spring. This parameter change enables the slip torque when rotation is input from the driving part to be smaller, allowing efficient operation while still providing reliable torque transmission when needed
3Productivity
If the internal coil spring clamping force is decreased, then the slip torque from driven part is decreased, but it becomes smaller than desired for reliable torque transmission
Solution Approach 1:
The clamping force parameter of the internal coil spring is specifically adjusted to be relatively large compared to the external coil spring. This parameter change ensures that the slip torque when rotation is input from the driven part is larger, providing reliable torque transmission while allowing efficient operation in the opposite direction
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 allows for a smaller slip torque when rotation is input from the driving part and a larger slip torque when rotation is input from the driven part, enabling efficient operation and reliable torque transmission in both directions.
Implementation Method 1
an external coil spring (42) is mounted on the outer peripheral surface of the outer race (8), the external coil spring in a free state has an inner diameter smaller than the outer diameter of the outer race (8), and the external coil spring clamps the outer race with a relatively small clamping force
Implementation Method 2
an internal coil spring (48) is mounted on the outer peripheral surface of the inner race (10), the internal coil spring in a free state has an inner diameter smaller than the outer diameter of the inner race (10), 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 the first predetermined torque, the auxiliary member and the housing rotate integrally, namely, the rotation torque is transmitted
Data Source
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AI summary
Provided is a novel bidirectional torque limiter, 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.