Pump Motor Miniaturization via Axial Commutator Overlap
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Solution Overview
Problem
The miniaturization of DC motors for automotive applications is hindered by the difficulty in shortening the output shaft while maintaining rotor diameter and balance, leading to unsatisfactory maneuverability and increased noise due to the radial arrangement of the commutator and axial biasing of the brush, which complicates the miniaturization of the motor in both axial and radial directions.
Innovation Solution
A motor design featuring a core with radially extending teeth and wound windings, a cylindrical commutator with electrical contact points, and a magnetic field body with six magnetic poles, where the second bearing and commutator overlap the windings in the axial direction, allowing for a shortened output shaft and enhanced miniaturization by overlapping components to reduce the motor's cross-sectional area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the commutator is arranged at the radially inner side of the armature core, then the output shaft length is shortened, but the rotor diameter increases causing unsatisfactory maneuverability and noise
Solution Approach 1:
The commutator is repositioned from a radial arrangement (at the radially inner side of the core) to an axial arrangement (at the axial end surface of the core). This dimensional change allows the output shaft to be shortened without increasing the rotor diameter, as the commutator now occupies axial space rather than radial space. The brush contact point is correspondingly positioned on the axial end surface, enabling the motor to achieve compact dimensions in both radial and axial directions.
2Length of moving object
If the brush is biased in the axial direction, then the output shaft length is reduced, but a biasing mechanism must be arranged adjacent to the armature increasing overall motor length
Solution Approach 1:
The brush holding function and the axial positioning function are merged into a single integrated brush holder structure. The brush holder is fixed to the magnetic field body and directly positions the brush contact point on the axial end surface of the core. This eliminates the need for a separate axial biasing mechanism, allowing the output shaft to be shortened without increasing the overall motor axial length.
3Area of moving object
If the motor is miniaturized in the radial direction, then the rotor diameter is reduced, but the commutator arrangement prevents further miniaturization
Solution Approach 1:
The commutator structure is reconfigured from a radial arrangement that occupies radial space to an axial arrangement where the commutator segments are positioned on the axial end surface of the core. This allows the rotor diameter to be minimized while the commutator and brush assembly occupies axial space instead, enabling true miniaturization in the radial direction without the complexity of radial commutator arrangements.
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 design achieves miniaturization in both axial and radial directions, improving maneuverability, reducing noise, and enhancing magnetic saturation, while maintaining optimal drive performance and assembly accuracy.
Implementation Method 1
A plurality of windings are wound around the plurality of teeth. A commutator is fixed to the output shaft... A magnetic field body has six magnetic poles.
Implementation Method 2
A bearing rotatably supports the output shaft.
Data Source
AI summary
A rotor is accommodated in a yoke housing. Six magnets are arranged at equal intervals in the circumferential direction on the inner circumferential surface of the yoke housing so as to face the rotor. The core is generally cylindrical and includes an annular portion at an anti-output side and a balance at an output side. The magnets have six poles so as to effectively narrow a basal path width of the core in which the line of magnetic force concentrates most and magnetic saturation is likely to occur most. This reduces the diameter of the core. Therefore, the motor is effectively miniaturized in the axial direction and in the radial direction without complicating the formation steps.