Electric Power Steering Terminal Block Design for Noise Reduction
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Solution Overview
Problem
The existing mechatronically-integrated electric power steering apparatus with an electric motor having a floating construction experiences increased operating noise due to the elastic deformation of the motor side connecting terminal, which affects the connecting state between the commutator and the brush, leading to enhanced noise levels.
Innovation Solution
The electric power steering apparatus incorporates a terminal block on the outer circumference of the electric motor's flange, with the motor side connecting terminal held on this block, and the control unit's connecting terminal arranged to overlap with it, allowing only vertical forces to be applied, reducing lurching of the brush holder and minimizing noise. This configuration also facilitates compactification and efficient assembly by overlapping the terminals and using a fixing screw for secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor side connecting terminal is elastically deformed to connect with the control unit side connecting terminal, then the gap between terminals is absorbed, but the brush holder lurches and operating noise increases
Solution Approach 1:
The connecting terminal is divided into a rigid portion and a flexible portion. The rigid portion maintains stable positioning and connection force, while the flexible portion absorbs gaps through elastic deformation. This segmentation prevents the brush holder from lurching during connection, thereby reducing operating noise while ensuring reliable terminal connection.
2Adaptability or versatility
If the electric motor with brush having floating construction is adopted, then assembly flexibility is improved, but brush holder stability deteriorates
Solution Approach 1:
The connecting terminal is segmented into rigid and flexible portions. The rigid portion provides stable positioning that maintains brush holder stability, while the flexible portion enables gap absorption and assembly flexibility. This segmentation allows the floating construction motor to be assembled adaptively without compromising brush holder stability.
Solution Approach 2:
Different portions of the connecting terminal have different mechanical properties: the rigid portion provides stable positioning and connection force, while the flexible portion provides elastic deformation capability. This local differentiation of mechanical properties enables both assembly flexibility and brush holder stability to be achieved simultaneously.
3Ease of manufacture
If the terminal connection structure is simplified, then manufacturing cost is reduced, but connection stability may be compromised
Solution Approach 1:
The connecting terminal is designed as a single integrated component with segmented rigid and flexible portions, eliminating the need for separate rigid and flexible elements. This segmentation approach simplifies manufacturing while maintaining connection stability through the inherent structural design that provides both rigid positioning and flexible gap absorption.
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 effectively reduces motor operating noise and allows for compactification of the electric power steering apparatus while ensuring secure and efficient connection of the motor and control unit terminals, even with a floating construction electric motor, by minimizing external forces on the motor side connecting terminal and using a fixing screw for secure attachment.
Implementation Method 1
an elastic body interposed between the brush holder and the housing and having the housing holding the brush holder. The electric motor is configured to block a pathway through which vibration generated when the armature rotates is transmitted from the commutator, the brush, the brush holder, and the housing by means of the elastic body
Implementation Method 2
elastically deforming the motor side connecting terminal toward the control unit side connecting terminal as disclosed in Patent Document 1, the elastic body floatingly holding the brush holder of the electric motor with brush is brought into s state where the elastic body is recessed and lurched
Data Source
AI summary
An electric motor and a control unit are juxtaposed in a speed reduction gear box. A terminal block is provided at an outer circumference of a flange proximate to a control unit of the electric motor. Terminal block surfaces of the terminal block are provided so that a plane direction faces a direction vertical to a shaft line of the electric motor. A motor side connecting terminal is held on the terminal block surface. The unit side connecting terminals provided at a position proximate to the electric motor of the control unit are arranged so as to overlap with the motor side connecting terminal on the terminal block surface to couple by a coupling portion (fixing screw).