Brush Timing Layout in DC Motors for Low Vibration and Noise
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Solution Overview
Problem
Existing direct-current motors used in vehicle control brakes, such as ABS, experience vibration and noise due to imbalances in the magnetic field caused by deviations in commutation timing among power supply brushes.
Innovation Solution
The direct-current motor is designed with a specific relationship between the number of slots and magnetic poles, and adjusted shift angles among imaginary lines to align the phases of armature and cogging torques, reducing the phase difference to 180°±80°, thereby minimizing vibration and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the direct-current motor uses conventional commutation timing without phase adjustment, then the structure is simple and easy to manufacture, but vibration and noise occur due to magnetic field imbalance
Solution Approach 1:
The patent adjusts the commutation timing phase by modifying the angular position relationship between the brush holder and stator, specifically setting the shift angle S to achieve a phase difference of 180°±80° between armature torque and cogging torque. This parameter change optimizes the magnetic field balance without altering the fundamental motor structure
Solution Approach 2:
The patent pre-adjusts the commutation timing to counteract the cogging torque effect before it causes vibration and noise. By setting the phase difference to 180°±80°, the armature torque preliminarily opposes the cogging torque, preventing the harmful vibration and noise from occurring during motor operation
2Object-affected harmful factors
If the phase difference between armature torque and cogging torque is not adjusted, then the manufacturing and assembly process is simple, but the motor generates excessive vibration and noise
Solution Approach 1:
The patent defines specific angular parameter relationships to achieve the desired phase difference. The shift angle S is calculated based on the angles C, D, E, and F, which represent various angular positions of teeth, segments, field magnets, and brush holder. By controlling these parameters within specific ranges, the phase difference is maintained at 180°±80°
Solution Approach 2:
The patent introduces an asymmetric angular relationship between the brush holder assembly position and the stator magnetic poles. Instead of symmetric alignment, the brush holder is positioned at a specific asymmetric angle to achieve the optimal phase difference, which effectively reduces vibration and noise while maintaining manufacturability
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
The motor effectively reduces vibration and noise by optimizing the commutation timing, achieving improved passenger comfort and operational silence.
Implementation Method 1
When a deviation in the timing of commutation occurs among the power supply brushes, an imbalance in a magnetic field is generated at coils of the armature
Implementation Method 2
a plurality of power supply brushes configured to slide along a plurality of segments of the commutator
Data Source
AI summary
A first line, which extends through a circumferential center of a tooth, and a second line, which extends through a circumferential center of an undercut between two segments adjacent to the tooth, intersect at an angle C. A third line, which extends through a magnetic-flux-free region of a magnet, and a fourth line, which extends through a circumferential center of a power supply brush, intersect at an angle D. The third line and a fifth line, which extends through a circumferential center of one of magnetic poles of the magnet, intersect at an angle E. A reference line of a stator and a sixth line, which extends through a reference point of a brush holder, intersect at an angle F. A shift angle S, which is obtained by C+D−E+F, is set such that a phase difference between an armature torque and a cogging torque is 180°±80°.