Worm Reducer Biasing Spring for Noise Suppression and Torque Efficiency
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Solution Overview
Problem
Existing worm reducers in electric power steering apparatuses face challenges in suppressing abnormal noises during reverse torque input while maintaining high torque transmission efficiency during normal operation.
Innovation Solution
The worm reducer incorporates a biasing plate spring with a non-linear spring characteristic, where the spring constant increases with deflection, and an elastic clamping means to effectively manage engaging reaction forces and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the spring constant of the biasing spring is increased to suppress abnormal noises during reverse torque input, then the suppression of impact noise improves, but the torque transmission efficiency during normal operation deteriorates due to increased frictional force
Solution Approach 1:
The patent applies the dynamics principle by making the spring constant variable rather than fixed. The biasing spring is designed with a non-linear elastic characteristic where the spring constant changes based on the deflection amount. During normal operation with small deflections, the spring constant is low to minimize friction and maintain high torque transmission efficiency. During reverse torque input with large deflections, the spring constant increases to suppress impact noise and collision forces.
Solution Approach 2:
The patent implements parameter changes by designing the biasing spring with varying elastic characteristics. The spring constant is not a fixed parameter but changes dynamically with the deflection amount. This allows the system to optimize performance for different operating conditions: low spring constant for efficient torque transmission during normal operation, and high spring constant for noise suppression during reverse torque input.
2Loss of energy
If the spring constant of the biasing spring is decreased to maintain high torque transmission efficiency during normal operation, then the frictional force at the engaging portion is reduced, but the suppression of impact noise during reverse torque input deteriorates
Solution Approach 1:
The patent applies the dynamics principle by making the spring constant variable rather than fixed. The biasing spring is designed with a non-linear elastic characteristic where the spring constant changes based on the deflection amount. During normal operation with small deflections, the spring constant is low to minimize friction and maintain high torque transmission efficiency. During reverse torque input with large deflections, the spring constant increases to suppress impact noise and collision forces.
Solution Approach 2:
The patent implements parameter changes by designing the biasing spring with varying elastic characteristics. The spring constant is not a fixed parameter but changes dynamically with the deflection amount. This allows the system to optimize performance for different operating conditions: low spring constant for efficient torque transmission during normal operation, and high spring constant for noise suppression during reverse torque input.
3Device complexity
If a constant spring constant is used in the biasing spring, then the structure is simple, but it is impossible to simultaneously suppress abnormal noises during reverse torque input and maintain high torque transmission efficiency during normal operation
Solution Approach 1:
The patent applies the dynamics principle by making the spring constant variable rather than fixed. The biasing spring is designed with a non-linear elastic characteristic where the spring constant changes based on the deflection amount. During normal operation with small deflections, the spring constant is low to minimize friction and maintain high torque transmission efficiency. During reverse torque input with large deflections, the spring constant increases to suppress impact noise and collision forces.
Solution Approach 2:
The patent implements parameter changes by designing the biasing spring with varying elastic characteristics. The spring constant is not a fixed parameter but changes dynamically with the deflection amount. This allows the system to optimize performance for different operating conditions: low spring constant for efficient torque transmission during normal operation, and high spring constant for noise suppression during reverse torque input.
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 efficiently suppresses abnormal noises during reverse torque input and ensures high torque transmission efficiency during normal operation by dynamically adjusting the spring constant and clamping force.
Implementation Method 1
The biasing plate spring is elastically deformed, and biases the outer fitting member toward the worm wheel side by an elastic restoring force of the biasing plate spring
Implementation Method 2
the biasing plate spring exhibits a non-linear spring characteristic in which a spring constant increases as a position of the fulcrum changes to approach the load point as an amount of deflection in the first direction increases
Data Source
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AI summary
[Problem] Provided is a worm reducer that easily achieves at a high level both suppression of abnormal noise generated when torque is reversely input and ensuring torque transmission efficiency during normal operation. [Solution] A worm reducer includes a biasing plate spring 6 that biases an inner diameter side member 5 toward a worm wheel 3. The biasing plate spring 6: is arranged on a far side from the worm wheel 3 in a biasing direction of the biasing plate spring 6 of a portion between an outer circumferential surface of the inner diameter side member 5 and an inner circumferential surface of an outer diameter side member 9; has a load point P that is a contact portion with the outer circumferential surface of the inner diameter side member 5, and a fulcrum S that is a portion of contact portions with the inner circumferential surface of the outer diameter side member 9 that is located closest to the load point P; and exhibits non-linear spring characteristics in which a spring constant increases as a position of the fulcrum S changes to approach the load point P as an amount of deflection in the first direction increases.