Bus Bar Module Layout for Compact Electric Power Steering Motors
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Solution Overview
Problem
Existing electric power steering devices face challenges in reducing the size of motors in both the axial and radial directions due to the configuration of connectors and wiring, leading to increased size and complexity.
Innovation Solution
The design incorporates a motor with divided coil groups and an electronic control device featuring a bus bar module with integrated connectors and power supply terminals, a circuit board, and a heat sink, allowing for reduced size and improved layout flexibility by optimizing wiring and component placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the connector direction is changed from axial to radial, then the axial size is reduced, but the radial size increases due to larger power supply wiring area
Solution Approach 1:
The patent changes the connector orientation from axial to radial direction, effectively using a different spatial dimension to resolve the size conflict. This allows the connector to protrude radially while keeping the axial footprint compact, accommodating the wiring harness connection without increasing the motor's axial length.
Solution Approach 2:
The connector is integrated into the motor housing structure, with the connector body nested within or attached to the motor case. This nesting approach allows the connector to be accommodated within the existing motor envelope, minimizing the increase in radial dimensions while maintaining functional connectivity.
2Power
If higher power is supplied to the motor, then the driving capability is improved, but the substrate area increases due to larger power supply wiring
Solution Approach 1:
The patent replaces traditional substrate-based power distribution with a bus bar system. The bus bar provides a low-resistance, high-current capability pathway that does not require large substrate copper traces, thereby maintaining compact substrate area while supporting higher motor power requirements.
Solution Approach 2:
The power supply system is segmented into distinct functional components: the bus bar for high-current power delivery, the connector for external connection, and the substrate for control circuitry. This segmentation allows each component to be optimized independently, with the bus bar handling power transmission without requiring increased substrate area.
3Device complexity
If the connector and power supply terminals are integrated into a bus bar module, then the device complexity is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent merges the connector and power supply terminals into a single bus bar module, reducing the total component count and assembly steps. This integration simplifies the overall device structure while the bus bar's inherent rigidity and standardized geometry facilitate precise positioning and connection.
Solution Approach 2:
The bus bar is designed with specific geometric parameters (cross-sectional area, length, mounting hole positions) that are optimized for both electrical performance and mechanical precision. By controlling these parameters during manufacturing, the integration precision is maintained while achieving component reduction.
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 motor's size in both axial and radial directions, enhancing the layout freedom and efficiency of the electric power steering device.
Implementation Method 1
a heat sink that has a groove on the anti-load side, has the bus bar module inserted in the groove, and supports the circuit board disposed on the anti-load side of the bus bar module
Implementation Method 2
heat sink
Implementation Method 3
a magnet provided at an anti-load side end of the shaft in order to control drive of the motor, and a circuit board disposed on the anti-load side of the shaft on an extended line thereof extending in an axial direction of the shaft... the rotation angle sensor is mounted on a first surface of the board body and is opposed to the magnet
Implementation Method 4
a motor stator including a stator core configured to rotate the motor rotor and a plurality of coil groups that are divided into at least two systems of first coil groups and second coil groups for each of three phases, and are configured to excite the stator core with three-phase alternating currents
Data Source
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AI summary
An electric drive device and an electric power steering device are provided that reduce the size of a motor in an axial direction parallel to a shaft and in a radial direction of the shaft. The electric drive device includes a bus bar module in which a connector, a first power supply terminal, a second power supply terminal, positive electrode bus bar wiring that electrically connects the connector to the first power supply terminal, and negative electrode bus bar wiring that electrically connects the connector to the second power supply terminal are integrally formed with the connector. The positive electrode bus bar wiring and the negative electrode bus bar wiring extend from the connector, bypass an extended line of the shaft, and are electrically connected to the circuit board in positions at distances from the connector larger than a distance from the connector to the extended line of the shaft.