Electric Power Steering Drive Unit Axial Volume Reduction
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Solution Overview
Problem
Conventional electric power steering devices have a large volume due to the arrangement of capacitors and connectors outside the motor's projection area, increasing the radial size and making them less compact.
Innovation Solution
The drive unit integrates a rotating electric machine, a frame member acting as a heat sink, and a controller where the heat generation element and electronic components are positioned within the motor's projection area, reducing the number of components and volume, especially along the axis, without increasing the radial volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitors and connectors are disposed outside the motor's projection area, then electrical connection is achieved, but the radial volume and overall device volume increase
Solution Approach 1:
The patent merges the capacitor and connector into the motor's projection area by integrating them with the motor housing. The capacitor is disposed within the projection area of the motor along the motor axis, and the connector is integrated with the motor housing, eliminating the need for separate external mounting spaces and reducing the overall radial volume.
2Temperature
If a separate heat sink is provided outside the frame member, then heat dissipation is achieved, but the number of components and axial volume increase
Solution Approach 1:
The patent merges the heat sink function with the frame member by forming the heat sink as an integral part of the frame member structure. The frame member includes a heat dissipation portion that extends axially, allowing heat generated by electronic components to be dissipated through the frame member itself, thereby eliminating the need for a separate heat sink component and reducing both component count and axial volume.
3Ease of manufacture
If electronic components are arranged outside the motor's projection area, then component mounting is achieved, but the axial size and volume increase
Solution Approach 1:
The patent arranges electronic components in the radial direction within the motor's projection area rather than extending axially. The substrate is disposed radially within the projection area of the motor, and electronic components are mounted on the substrate in a radial arrangement, utilizing the radial dimension for component placement instead of the axial dimension, thereby reducing the axial size while maintaining ease of manufacture.
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 minimizes the axial size of the drive unit while maintaining a compact radial size, allowing for easier installation in small spaces and efficient heat dissipation, thus enhancing the overall efficiency and compactness of the electric power steering device.
Implementation Method 1
the heat generation element is enabled to dissipate heat to the frame member
Implementation Method 2
the frame member serves as an outline of the rotating electric machine, while also serving as a heat sink
Data Source
AI summary
A drive unit includes a rotating electric machine, a frame member, and a controller. The rotating electric machine has a stator that has a winding wound on the stator, a rotor disposed relative to the stator, and a shaft rotating together with the rotor. The frame member is disposed on one axial end of the rotating electric machine. The controller includes a substrate attached on one surface of the frame member facing away from the rotating electric machine, a heat generation element disposed on a heat generation element mounting surface of the substrate, the heat generation element mounting surface facing the frame member, and an electronic component disposed on an electronic component mounting surface of the substrate.