Brushless Wiper Motor Shaft Layout for Lower Inertial Mass
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Solution Overview
Problem
Conventional wiper motors face challenges in reducing size and weight while minimizing electric noise, which is essential for versatile vehicle applications, as they often have heavy components like iron cores and commutators unsupported, leading to increased inertial mass and noise issues.
Innovation Solution
A brushless wiper motor design where the rotor is supported within the stator, with one end of the rotation shaft fixed to the rotor's axial center and the worm on the other end, utilizing first and second bearings to support the shaft, eliminating the need for components like coils and commutators at the unsupported end, thus reducing inertial mass and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If heavy components like iron core and commutator are arranged in the non-supported portion of the motor shaft to reduce size, then the motor size is reduced, but the inertial mass of the free end portion increases requiring large driving current
Solution Approach 1:
The patent extracts and removes the commutator and brush components from the motor shaft assembly. By eliminating these heavy components from the free end portion, the inertial mass is reduced while maintaining compact motor dimensions. This allows the motor to achieve small size without requiring large driving current to accelerate the removed components.
Solution Approach 2:
The patent replaces the mechanical brush-commutator system with a brushless motor design using electronic commutation. This substitution eliminates the need for physical contact components on the motor shaft, reducing inertial mass and improving energy efficiency while maintaining the motor's compact form factor.
2Volume of moving object
If brush unit is provided in the motor to achieve compact design, then the motor size is reduced, but electric noise is generated requiring countermeasures
Solution Approach 1:
The patent replaces the mechanical brush-commutator system with a brushless motor design using electronic commutation and permanent magnets. This substitution eliminates the arcing and contact noise associated with brushes while maintaining compact motor dimensions, thus reducing electric noise without sacrificing size reduction.
3Volume of moving object
If motor shaft is shortened to reduce size, then the motor compactness is improved, but the stability of rotation shaft operation deteriorates
Solution Approach 1:
The patent removes heavy components like the commutator from the motor shaft, which allows for a shorter shaft design. The extracted components are eliminated entirely in the brushless design, enabling compactness while the remaining shaft structure maintains stability through optimized support positioning.
Solution Approach 2:
The patent changes the support positioning parameters of the motor shaft, placing supports at optimized locations along the shaft length. This parameter optimization allows the shaft to be shorter while maintaining adequate stiffness and rotational stability, achieving compactness without sacrificing operational stability.
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 results in a more stable, energy-efficient, and quieter operation with reduced maintenance needs, as it eliminates the need for brushes and commutators, enhancing the motor's performance and reliability.
Implementation Method 1
a stator 32 provided with a coil 32b; a rotor 33 rotatably provided inside the stator 32
Implementation Method 2
the rotation shaft 34 is rotatably supported by only the first and second ball bearings 36, 37
Implementation Method 3
a rotor 33 having permanent magnets 33a attached to an outer surface
Data Source
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AI summary
In a brushless wiper motor, a rotor (33) is rotatably provided inside a stator (32) provided with a coil (32b), one end side of a rotation shaft (34) in the axial direction is fixed to the axial center of the rotor (33), a worm (35) is provided on the other end side of the rotation shaft (34) in the axial direction, the first and second bearings (36, 37) are respectively provided on one end side of the rotation shaft (34) in the axial direction and the other end side of the rotation shaft (34) in the axial direction than the worm (35) of the rotation shaft (34), the rotation shaft (34) is rotatably supported by only the first and second bearings (36, 37), and with the position of the first bearing (36) being defined as a reference position, a length thereof in the axial direction to the second bearing (37) is longer than a length thereof in the axial direction to the rotor (33). Since a commutator and other parts are not provided on a free end side of the rotation shaft (34), it is possible to provide a brushless wiper motor reduced in length of the rotation shaft (34), and reduced in inertial mass of the free end side of the rotation shaft (34).