Electric Power Steering Control Unit Axial Integration
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Solution Overview
Problem
Existing electric power steering devices face challenges in mounting due to large radial dimensions of the control unit, leading to increased product size, particularly in the radial direction, as a result of component arrangements that necessitate vertical placement of power modules and heat sinks, and horizontal placement of control boards, which limits mountable area and increases axial length.
Innovation Solution
The electric power steering device configures the control unit with main components arranged vertically, including a power module, control board, and heat sink, where the heat sink has a base portion on the motor side and a column portion extending along the output shaft's axis, allowing for a compact design by positioning the rotation sensor in a recess of the base portion and integrating the control unit with the motor in an axial direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the control unit is provided at an end portion of the motor on the opposite side to the output side, then the motor and control unit can be integrated, but the radial dimension of the control unit increases making it difficult to mount on vehicles
Solution Approach 1:
The patent changes the arrangement dimension of the control unit from radial to axial direction. The control unit is extended in the axial direction of the motor shaft, allowing integration with the motor while keeping the radial dimension compact for vehicle mounting.
Solution Approach 2:
The control unit is nested within the motor structure by positioning it at the non-output end of the motor, utilizing the motor housing and shaft space. The control unit's axial extension fits within the motor's overall envelope dimensions.
2Measurement precision
If the rotation sensor is provided on the control board facing a magnet at the end portion of the output shaft, then the sensor can detect rotation, but the axial length of the product increases
Solution Approach 1:
The rotation sensor is nested within the control unit structure, with the sensor and magnet arranged to face each other through minimal spacing. The sensor is positioned on the control board such that it detects the magnet at the end portion of the output shaft without requiring excessive axial length.
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 effectively reduces the product size in both radial and axial directions, maintaining component functionality while allowing for independent assembly of the motor and control unit, improving heat dissipation and reducing noise interference.
Implementation Method 1
a heat sink configured to allow heat radiation from the control unit
Implementation Method 2
a rotation sensor configured to detect rotation of the sensor rotor
Data Source
AI summary
An electric power steering device includes a motor and a control unit that are arranged coaxially with each other in an axial direction of an output shaft and integrated with each other. The control unit includes power modules configured to supply current to the motor, a heat sink, a control board configured to output a control signal to the power modules, and a rotation sensor. The power modules, a column portion of the heat sink, and the control board are arranged in parallel to the axial direction of the output shaft. The rotation sensor is provided in a recess formed in a base portion of the heat sink at an opposite position to a sensor rotor mounted to an end portion of the output shaft on the control unit side.