Electric Power Steering Driver Unit Heat Dissipation
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Solution Overview
Problem
Conventional driver units for electric power steering devices require a large mounting surface due to the arrangement of large-size electronic components, necessitating the use of multiple circuit boards and separate heat sinks, which increases size and complexity.
Innovation Solution
A driver unit design where the substrate is mounted on a frame member that serves as both a structural support and a heat sink, allowing high-density component mounting with heat dissipation directly to the frame, eliminating the need for a separate heat sink and reducing the unit's axial size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large-size electronic components are arranged in a row on a circuit board, then the components can be mounted, but the mounting surface area increases and the driver unit size becomes large
Solution Approach 1:
The patent transitions from a two-dimensional row arrangement of components on the circuit board to a three-dimensional configuration where components are mounted on both sides of the board. The opposite surface of the circuit board is utilized for mounting additional components, effectively doubling the available mounting area and reducing the footprint requirements.
2Temperature
If a separate heat sink is added to dissipate heat from electronic components, then heat dissipation is improved, but the device complexity and axial size increase
Solution Approach 1:
The patent merges the heat dissipation function with the existing frame member structure. The frame member, which already provides mechanical support and housing for the motor, is designed to also serve as a heat sink with integrated heat dissipation fins. This eliminates the need for a separate heat sink component and reduces overall device complexity.
Solution Approach 2:
The frame member is designed to perform multiple functions simultaneously: structural support, housing, and heat dissipation. By making the frame member universal, the patent reduces the total number of components needed while maintaining effective heat dissipation capability.
3Quantity of substance
If multiple circuit boards are used to accommodate all electronic components, then component mounting is enabled, but the axial size of the driver unit increases
Solution Approach 1:
The patent utilizes the z-dimension (both sides of the circuit board) for component mounting instead of only the x-y plane. By mounting components on both the front and back surfaces of a single circuit board, the design accommodates all electronic components without requiring additional stacked boards, thereby reducing the axial dimension.
4Ease of operation
If the driver unit is designed with compact size for small space installation, then workability in small spaces is improved, but the mounting surface area for electronic components is reduced
Solution Approach 1:
The patent resolves this contradiction by utilizing both surfaces of the circuit board for component mounting. This effectively doubles the available mounting area within the same footprint, allowing compact driver unit design while still accommodating all necessary electronic components.
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 design enables a more compact and efficient driver unit with improved workability in small spaces, such as near engines, by integrating heat dissipation into the frame member and allowing for high-density electronic component mounting.
Implementation Method 1
The driver element includes an inverter for switching an electric current supplied to the winding and is mounted on a first surface of the substrate facing the frame member, for dissipating heat to the frame member
Implementation Method 2
heat of the IC components, which is relatively large due to the integration of many components in one place, is dissipated toward the frame member
Data Source
AI summary
A driver unit has a rotating electric machine and a frame member that is disposed on one axial end of the rotating electric machine. A substrate is fixed onto one surface of the frame member which faces away from the rotating electric machine. Switching elements constituting inverters for switching power supply to winding groups are mounted on a first surface for enabling heat dissipation toward the frame member. An Integrated Circuit (IC) is mounted on the first surface for enabling heat dissipation toward the frame member. An electronic component is mounted on a second surface at an overlapping position that at least partially overlaps a mounting position of the IC.