Brushless DC Motor Axial Sensor Arrangement for Wiper Thickness Reduction
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Solution Overview
Problem
Brushless DC electric motors for motor vehicle wiper systems face challenges in reducing size, particularly when incorporating position sensors, which increases spatial constraints and thickness.
Innovation Solution
The motor design features a rotor with three multipolar axial layers in the form of crowns, each with six magnetic poles, and a position determination system using three Hall effect sensors arranged in a triangle configuration, allowing for reduced thickness and precise angular position monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors are installed in the motor to determine rotor position, then electronic switching precision is improved, but the motor size and thickness increase
Solution Approach 1:
The patent transitions from radial sensor arrangement to axial sensor arrangement, changing the spatial dimension in which sensors are positioned. The sensors are installed in an axial plane rather than radially around the rotor, allowing them to detect the position of multipolar axial layers without increasing radial dimensions, thus reducing overall motor thickness while maintaining measurement precision.
Solution Approach 2:
The rotor is divided into multiple multipolar axial layers, each with its own position sensor. This segmentation allows each sensor to monitor a specific layer's position independently, enabling precise electronic switching while using thinner individual axial layers, thereby reducing the total thickness of the rotor assembly.
2Power
If multiple multipolar axial layers are used in the rotor, then torque and power are improved, but the complexity of the magnet structure increases
Solution Approach 1:
Multiple multipolar axial layers are merged into a single integrated rotor structure. The axial layers are stacked along the rotation axis to form one cohesive rotor assembly, simplifying manufacturing and assembly while maintaining the torque-enhancing benefits of multiple layers. The sensor system also merges detection of all layers into a unified position determination system.
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 the size and thickness of the motor while maintaining high precision in electronic switching of the coils, optimizing the motor's spatial efficiency.
Implementation Method 1
The position determination system uses three Hall effect sensors arranged in a triangle configuration, allowing for reduced thickness and precise angular position monitoring
Implementation Method 2
The electric motor is configured so that, when the coils are supplied with electric current, a magnetic field is created, causing a rotational movement of the multipolar magnet around an axis of rotation
Data Source
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AI summary
The invention relates to a brushless DC electric motor for a motor vehicle wiper system, comprising a stator (3) and a rotor (2), the stator (3) comprising a plurality of electromagnetic excitation coils (4) of the rotor (2) and the rotor (2) comprising a multipolar magnet (5) mounted to be driven by a rotational movement about an axis of rotation (L) and provided with at least three multipolar axial layers (7), the electric motor (1) comprising a rotor position determination device (8), said rotor position determination device (8) comprising at least three position sensors (9) of one of said at least three multipolar axial layers (7), each position sensor (9) being associated respectively with one of the multipolar axial layers (7),the position sensors (9) being installed in a plane (P) containing a direction parallel to the axis of rotation of the multipolar magnet (5) while being misaligned with respect to each other.