Terminal Connection Structure for Electric Power Steering

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The existing terminal connection structures in electric power steering systems face issues with increased contact resistance due to positional displacement of terminals during assembly, leading to reduced contact area and pressure, which can affect the reliability and lifespan of the motor and the entire system.

Innovation Solution

A terminal connection structure featuring a first terminal with a held portion, a second terminal with a plate-shaped base and holding portions, and a bridge portion that deforms to maintain contact pressure and area, along with a guide hole and tapered portions to efficiently transfer reaction forces and facilitate accurate positioning, thereby inhibiting the increase in contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If terminals are connected using a pressing mechanism with holding members, then electrical connection is established, but positional displacement during assembly reduces contact area and pressure, increasing contact resistance

Engineering Contradiction:
Improvecontact resistanceVSAvoidpositioning accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The guide hole is provided in advance in the first terminal, and the second terminal is guided to insert into this predetermined position before pressing. This preliminary positioning action ensures that even if assembly machine accuracy is insufficient, the terminals will be properly aligned, preventing positional displacement and maintaining adequate contact area and pressure.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The guide hole acts as an intermediary element between the first and second terminals. It mediates the positioning process by providing a physical constraint that guides the second terminal into the correct position relative to the first terminal, thereby eliminating the need for high-precision assembly machine positioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If holding members are used to secure the terminal connection, then mechanical strength is provided, but displacement during assembly causes inclination of holding members, reducing contact quality

Engineering Contradiction:
Improvemechanical strengthVSAvoidcontact quality
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

Positioning is performed in advance through the guide hole structure before the pressing operation. The guide hole constrains the second terminal to the correct position, so when holding members are subsequently engaged, they do so without inclination, maintaining both mechanical strength and contact quality.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If assembly machine accuracy is relied upon for terminal positioning, then connection speed is maintained, but positional displacement occurs, reducing contact area and pressure

Engineering Contradiction:
Improveassembly speedVSAvoidcontact resistance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The guide hole serves as a mechanical intermediary that takes over the positioning function from the assembly machine. This allows the assembly process to proceed at high speed without relying on machine accuracy, as the guide hole automatically ensures proper alignment through its physical structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The terminal connection structure is self-positioning through the guide hole mechanism. The second terminal self-aligns with the first terminal by being guided into the guide hole during insertion, eliminating the need for precision control from the assembly machine and maintaining both speed and reliability.

Inventive Principle:
Principle #25Self-service

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

The proposed terminal connection structure effectively maintains contact pressure and area, reducing contact resistance and enhancing the lifespan of the motor, actuator, and electric power steering system by ensuring precise alignment and deformation of the bridge portion to correct attitude and maintain contact.

Implementation Method 1

a plate-shaped bridge portion projecting from the other end of the base portion in a direction crossing relative to the base portion... Deformation of the bridge portion corrects an attitude of a holding portion

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

When a second terminal is inserted into a guide hole, if a position of the second terminal relative to a guide hole is displaced in a width direction, a reaction force is applied to the second terminal from the guide hole

Methodology Applied
Scientific EffectReaction force: Reaction (physics)

Data Source

PatentEP3223375B1Terminal connection structure, motor, actuator, electric power steering device, and vehicle
Publication Date: 2019.03.13 NSK LTD
  • EP3223375B1 patent drawingFigure 1
  • EP3223375B1 patent drawingFigure 2
  • EP3223375B1 patent drawingFigure 3

AI summary

A terminal connection structure includes a first terminal, a second terminal, and a terminal guide. The first terminal includes a held portion. The second terminal includes a plate-shaped base portion, a pair of holding portions projecting from one end of the base portion to hold the held portion from both sides, and a plate-shaped bridge portion projecting from the other end of the base portion in a direction crossing relative to the base portion. The terminal guide includes a guide hole having one end at which the first terminal is disposed, and the other end from which the second terminal is inserted.