Electric Power Steering Worm Drive Phase Design for Noise Reduction
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Solution Overview
Problem
Conventional electric power steering devices experience significant vibration and noise due to the synergistic effects of vibrations and noises from the electric motor, joint, and gear configurations.
Innovation Solution
The assist mechanism includes an electric motor, a shaft-shaped member with a worm engaged with a worm wheel, and a coupling that couples the output shaft of the electric motor and the shaft-shaped member, with rotation orders of these components being prime to each other to prevent concurrence of vibrations and noises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional electric power steering devices use standard rotation orders for the electric motor, worm, and coupling, then the device structure is simple and easy to manufacture, but vibration and noise occur due to synergistic effects of these components
Solution Approach 1:
The patent changes the rotation order parameters of the electric motor, worm, and coupling to be prime numbers relative to each other. This parameter modification shifts the vibration and noise occurrence timings of these components, preventing their synergistic effects and reducing overall vibration and noise in the steering device.
2Object-affected harmful factors
If the rotation orders of the electric motor, worm, and coupling are made different (prime to each other), then vibration and noise are reduced, but the design and manufacturing complexity increases
Solution Approach 1:
The patent specifies that the rotation order of the electric motor, the rotation order of the worm, and the rotation order of the coupling should be prime numbers relative to each other. This parameter setting is applied during the design and manufacturing stages to ensure that vibration and noise from these components do not occur simultaneously, thereby reducing overall noise while maintaining manufacturability through clear design guidelines.
3Object-affected harmful factors
If standard gear configurations are used in the worm and coupling, then the device is simple to manufacture, but vibration and noise from these components coincide with the electric motor vibrations
Solution Approach 1:
The patent modifies the rotation order parameters of the worm and coupling gear configurations to be prime numbers relative to the electric motor's rotation order. This coordination ensures that the vibration frequencies of these mechanical components do not coincide with the electric motor vibrations, reducing synergistic noise effects while maintaining reasonable manufacturing precision through standardized gear design approaches.
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 effectively reduces vibration and noise by shifting the timings of occurrence of these phenomena, ensuring that the rotation orders of the electric motor, worm, and coupling are different, thereby preventing larger vibrations and noises.
Implementation Method 1
an electric motor in which a rotor has a magnet and a stator has a winding
Implementation Method 2
a shaft-shaped member in which a worm engaged with a worm wheel is formed
Data Source
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AI summary
An assist mechanism includes: an electric motor in which a rotor has a magnet and a stator has a winding; a shaft-shaped member in which a worm engaged with a worm wheel is formed; and a coupling that couples an output shaft of the electric motor and the shaft-shaped member to each other. The smallest rotation order among rotation orders of the electric motor and a rotation order of the worm are prime to each other.