Electric Drive Device Axial ECU Mounting 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 arrangement of power supply and control circuit units on boards, which increases the size of the ECU housing and requires efficient heat radiation, especially with redundant systems for safety.
Innovation Solution
The electric drive device incorporates a heat radiation base body where electronic control units are arranged along its extension direction, with boards fixed to the base body, allowing for slanted mounting to increase the heat storage and removal area, thus reducing the device's size and enhancing heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If power supply circuit unit, power conversion circuit unit and control circuit unit are mounted on two boards arranged in radial direction, then electronic control function is achieved, but size of ECU housing increases in radial direction
Solution Approach 1:
The patent transitions from radial arrangement to axial arrangement of circuit boards. Specifically, the first and second control circuit boards are arranged in the axial direction of the motor housing, allowing them to extend along the axis rather than radially outward. This dimensional change enables the ECU housing to maintain a compact radial profile while accommodating all necessary circuit boards axially along the motor housing.
Solution Approach 2:
The patent integrates the ECU housing with the motor housing structure. The ECU housing is positioned within the motor housing, and the circuit boards are mounted axially along the motor housing. This merging of housing structures eliminates the need for a separate radial ECU housing extension, reducing the overall radial size while maintaining all electronic control functions.
2Reliability
If redundant system with two electronic control units is implemented, then safety and reliability are improved, but size of ECU housing increases
Solution Approach 1:
The patent arranges the first and second electronic control units (each on separate control circuit boards) in the axial direction rather than radially. This allows the redundant system components to be stacked axially along the motor housing, maintaining a compact radial footprint while accommodating both control units for redundancy. The axial arrangement enables the housing volume to be optimized without compromising the redundant system configuration.
3Volume of stationary object
If electronic control unit size is reduced, then device compactness is improved, but heat radiation efficiency deteriorates
Solution Approach 1:
The patent extracts the heat radiation function from the ECU housing and assigns it to a dedicated heat radiation fin structure. The heat radiation fins are provided on the outer peripheral surface of the motor housing, separate from the electronic control units. This extraction allows the ECU housing to be minimized for compactness while the dedicated fin structure handles heat dissipation efficiently, preventing thermal interference with the reduced-size control units.
Solution Approach 2:
The patent segments the housing into functional zones: the ECU housing contains only the electronic control units with minimized volume, while the motor housing provides structural support and heat radiation surfaces. The circuit boards are arranged axially within the ECU housing away from the motor housing, creating thermal separation. This segmentation allows independent optimization of both compactness and heat radiation efficiency.
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 radial direction while ensuring rapid and efficient heat removal from electronic components, improving the heat resistance and reducing the overall size and weight of the electric power steering device.
Implementation Method 1
a board which is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed
Data Source
AI summary
An electric drive device has a motor housing accommodating an electric motor, a heat radiation base body fixed to an end surface, which is opposite side to an output shaft portion of a motor rotation shaft, of the motor housing and extending in a rotation shaft direction that is opposite side to output shaft portion, one electronic control unit of redundant system, arranged along direction in which heat radiation base body extends and having board, fixed to the heat radiation base body with thermal conduction to heat the radiation base body allowed, and the other electronic control unit of redundant system, arranged along direction in which the heat radiation base body extends and having a board, fixed to the heat radiation base body with thermal conduction to heat radiation base body allowed. Boards of both electronic control units are fixed to the heat radiation base body with boards slanting with respect to an extension direction of the heat radiation base body.