Electric Power Steering Inverter Layout for Compact Heat Dissipation
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Solution Overview
Problem
Existing electric power steering devices face challenges with heat management, as the heat radiating structure requires a significant area for effective heat dissipation, leading to increased equipment size and weight.
Innovation Solution
The electric power steering device integrates a heatsink with a bearing that supports the motor's rotary shaft, and a circuit board with the inverter circuit disposed on the heatsink's surface. The heat generating elements are positioned in a projection region of the circuit board that matches the heatsink's outer shape, allowing for efficient heat transfer and dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat radiating material is provided between the circuit board and heatsink to efficiently radiate heat, then heat dissipation performance is improved, but the size of the equipment and product weight increase
Solution Approach 1:
The patent combines the heat radiating function with the housing structure by forming the heatsink as an integral part of the motor housing. The housing serves dual purposes: structural support and heat dissipation. This eliminates the need for separate heat radiating materials and structures, thereby reducing overall weight while maintaining effective heat dissipation from the inverter circuit.
2Temperature
If a heat radiating material is provided between the circuit board and heatsink to efficiently radiate heat, then heat dissipation performance is improved, but the size of the equipment increases
Solution Approach 1:
The housing is designed to integrate multiple functions: it provides structural support for the motor, serves as a heatsink for thermal management, and eliminates the need for separate heat radiating materials. This multi-functional design reduces the overall equipment size by consolidating components that would otherwise be separate.
Solution Approach 2:
The housing structure performs multiple functions simultaneously: it acts as a mechanical enclosure, a mounting structure for the circuit board, and a heatsink for heat dissipation. This multi-functionality eliminates the need for dedicated heat radiating structures, thereby reducing equipment size.
3Temperature
If the circuit board and heatsink are closely attached by screw-fixing to radiate heat, then heat dissipation is improved, but the device complexity increases
Solution Approach 1:
The heatsink is formed as an integral part of the housing structure, eliminating the need for separate attachment mechanisms. The housing itself serves as the heat dissipation structure, reducing the number of components and assembly steps required while maintaining effective heat transfer from the inverter circuit.
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 reduces the heating value of the heat generating elements, enabling a downsized and simplified heat radiating structure, which in turn reduces product weight and manufacturing costs while maintaining effective heat dissipation.
Implementation Method 1
a heat radiating structure that dissipates the heat of the heat generating element
Implementation Method 2
radiate heat generated from the heat generating element of the circuit board to a heatsink
Data Source
AI summary
An electric power steering device (1, 1A, 1B) includes a motor (2), a heatsink (32) in which a bearing (33) configured to rotatably support a rotary shaft (21) of the motor is provided, and a circuit board (31), on which an inverter circuit (4, 4A, 4B) configured to drive the motor, disposed on a surface of the heatsink opposite to the motor, a heat generating element (8, 8A, 8B, 9, 9A, 9B) that constitutes the inverter circuit being disposed in a projection region (42) of the circuit board on which an outer shape of the heatsink is projected when seen in an axial direction of the rotary shaft, and the inverter circuit being configured to be driven by a first voltage of 20 V or more.