Electric Power Steering ECU Layout for Compact Heat Dissipation
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Solution Overview
Problem
The existing electric power steering devices face challenges in size reduction in the radial direction due to the integration of electronic control units and the need for efficient heat radiation, which is exacerbated by the use of multiple boards and redundant systems, leading to increased size and complexity.
Innovation Solution
The electric drive device incorporates a motor housing with supporting stems and a heat radiation base body, where electronic control units are arranged along the axial direction with thermal conduction, allowing for size reduction in the radial direction while efficiently radiating heat through the motor housing, and fixing bolts are used to connect the heat radiation base body without increasing the radial size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple boards and redundant systems are integrated into the ECU housing, then reliability is improved, but the device complexity and radial size increase
Solution Approach 1:
The patent merges the power supply circuit unit, power conversion circuit unit, and control circuit unit onto a single board instead of using multiple separate boards. This integration reduces the number of components and simplifies the ECU housing structure while maintaining the redundant system configuration for improved reliability
Solution Approach 2:
The single board is designed to perform multiple functions by integrating power supply, power conversion, and control capabilities. This multi-functional approach eliminates the need for separate dedicated boards for each function, reducing overall device complexity while supporting the redundant system architecture
2Volume of stationary object
If the ECU housing size is reduced in the radial direction, then the volume of the electric power steering device is decreased, but heat radiation efficiency deteriorates
Solution Approach 1:
The patent shifts heat radiation from the radial direction to the axial direction by positioning heat-generating components near the output shaft end and utilizing the axial space for heat dissipation. This dimensional transition allows compact radial design while maintaining effective heat radiation through the axial pathway
3Ease of manufacture
If boards are arranged in the radial direction, then ease of manufacture is improved, but the area of the ECU housing increases
Solution Approach 1:
The patent transitions from radial arrangement of multiple boards to axial arrangement on a single board. This repositioning in the axial dimension consolidates the footprint in the radial direction, reducing ECU housing area while maintaining manufacturing simplicity through standardized board mounting procedures
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 achieves size reduction in the electric drive device while maintaining effective heat radiation, reducing the overall size and component count, and enhancing product competitiveness by simplifying the assembly process.
Implementation Method 1
electronic control units are arranged along the axial direction with thermal conduction, allowing for size reduction in the radial direction while efficiently radiating heat through the motor housing
Data Source
AI summary
An electric drive device has a motor housing accommodating therein an electric motor; a pair of supporting stems arranged so as to face to each other on an end surface, which is an opposite side to an output shaft portion of a rotation shaft of the electric motor, of the motor housing and extending in a direction of the rotation shaft which is an opposite direction to the output shaft portion; a heat radiation base body arranged between the pair of supporting stems and extending in the same direction as those of the supporting stems; fixing bolts screwed into the heat radiation base body from a radially outer side to a radially inner side through the supporting stems and connecting the supporting stems and the heat radiation base body; one electronic control unit of a redundant system, arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed; and the other electronic control unit of the redundant system, arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed.