Electric Power Steering Motor Insulating Member Positioning

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Solution Overview

Problem

In electric power steering systems, the wide spacing between the controlling circuit and the power supplying portion of the electric motor complicates assembly due to longer connecting terminals and varying connection positions, making it difficult to stabilize the connecting terminal position without compromising ease of assembly.

Innovation Solution

An insulating member is disposed on the case of the controlling unit to position the connecting terminal, reducing irregularities and facilitating assembly by ensuring stable connections and preventing dislodging, with materials like polyphenylene sulfide, nylon resin, or bakelite providing necessary flame retardancy, heat resistance, and insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the spacing between the controlling circuit and the power supplying portion is increased, then heat radiation from the controlling circuit is improved, but the connecting terminal length increases and assembly becomes more difficult

Engineering Contradiction:
Improveheat radiationVSAvoidassembly difficulty
Core Design Contradiction:
TemperatureVSEase of operation

Solution Approach 1:

An insulating member is introduced as an intermediary component between the controlling circuit and the power supplying portion. This insulating member serves multiple functions: it provides electrical insulation, facilitates heat radiation from the controlling circuit, and most importantly, provides positioning functionality to stabilize the connecting terminal position. By incorporating positioning protrusions or positioning holes in the insulating member, the patent resolves the assembly difficulty caused by increased spacing while maintaining the heat radiation benefit.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the connecting terminal is made longer to bridge the gap, then electrical connection is maintained, but positioning accuracy decreases and connection stability deteriorates

Engineering Contradiction:
Improveelectrical connectionVSAvoidpositioning accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The insulating member acts as a mediator that provides positioning protrusions or positioning holes to guide and stabilize the connecting terminal. This positioning structure ensures that the connecting terminal maintains accurate positioning and stable connection, eliminating the positioning accuracy problems associated with longer connecting terminals.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The insulating member is pre-installed on the controlling unit with built-in positioning features (protrusions or holes) that guide the connecting terminal during assembly. This preliminary positioning action ensures that the connecting terminal is correctly positioned before final assembly, preventing connection instability and maintaining manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2666701B1Electric motor device for electric power steering and electric power steering device
Publication Date: 2020.03.04 MITSUBISHI ELECTRIC CORP
  • EP2666701B1 patent drawingFigure 1~2
  • EP2666701B1 patent drawingFigure 3~4
  • EP2666701B1 patent drawingFigure 5~6

AI summary

In conventional electric power steering electric motor apparatuses, fastening and dismantling are facilitated by screws, but because spacing between a controlling circuit and a power supplying portion of an electric motor is wider, connecting terminals that project outward from a controlling circuit toward the electric motor are longer, and one problem has been that connecting positions with a power supply part of the electric motor vary, making assembly difficult. An electric power steering motor apparatus includes: an electric motor including: a stator; and a rotor that is disposed inside the stator; and a controlling unit including: a driving circuit that is connected to the stator to supply electric power; a controlling circuit that controls the driving circuit; and a housing that covers the driving circuit and the controlling circuit, and to which the electric motor can be mounted, wherein: the electric motor and the controlling unit are configured approximately coaxially; the electric power steering electric motor apparatus includes: a power supplying portion that projects outward from the electric motor; and a connecting portion that projects outward from the controlling unit, and that is connected to the power supplying portion; and the connecting portion is held on the housing by means of an insulating member.