Motor Unit Sensor Positioning via Housing Groove
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Solution Overview
Problem
Existing sliding door automatic opening/closing devices for vehicles face challenges in accurately positioning the electric motor's sensor to detect the rotor's circumferential position, leading to inaccuracies in energization timing control.
Innovation Solution
A motor unit with a housing that includes a substrate accommodating portion, a positioning portion, and a fixing member to accurately position the control substrate and stator, allowing precise alignment of the sensor relative to the electric motor, combined with a speed reduction mechanism using a planetary gear system to reduce vibrations and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sensor is positioned on the circuit substrate without a positioning portion, then the device complexity is reduced, but the measurement precision of the rotor position deteriorates
Solution Approach 1:
A positioning portion is introduced as an intermediary component between the circuit substrate and the sensor. This positioning portion includes a positioning protrusion that fits into a positioning groove on the sensor, thereby achieving precise sensor positioning without increasing overall device complexity. The positioning portion acts as a mediator that transfers the positioning function from a complex alignment system to a simple mechanical fit.
2Ease of manufacture
If the stator is not fixed to the housing, then the ease of manufacture is improved, but the measurement precision of the sensor relative to the electric motor deteriorates
Solution Approach 1:
The stator is pre-fixed to the housing before the circuit substrate is assembled. This preliminary action establishes a stable reference frame early in the assembly process, ensuring that the sensor will be positioned accurately relative to the electric motor. By fixing the stator first, the subsequent assembly of the circuit substrate can proceed with guaranteed alignment accuracy.
3Measurement precision
If high-accuracy positioning structures are added to the housing, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
Instead of making the entire housing structure complex, the positioning portion is localized to a specific area on the housing. The positioning protrusion and groove are concentrated in one location, providing high-accuracy positioning only where needed (at the sensor location). The rest of the housing maintains its simple structure, thereby achieving measurement precision improvement without significant increase in overall device complexity.
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 solution enables high-accuracy positioning of the sensor, improving the control of the electric motor's energization timing and reducing vibrations and noise during operation, resulting in a more reliable sliding door automatic opening/closing mechanism.
Implementation Method 1
a magnetic field detection element such as a Hall element which is provided on a circuit substrate to detect the magnetic field of the sensor magnet
Data Source
AI summary
Disclosed is a motor unit including: an electric motor; a motor housing (6) configured to accommodate the electric motor; and a control substrate (70) including a sensor element (72S) to detect a position of an inner rotor of the electric motor in a rotational direction. The motor housing (6) includes a substrate accommodating portion (80) configured to accommodate at least a portion of the control substrate (70); a positioning portion (81) that is formed in the substrate accommodating portion (80), and positions the control substrate (70); and a screw configured to fix a stator of the electric motor to the positioning portion (81).