Worm Reducer Assembly Using Compressed Spring Jig

Solution Overview

Problem

The existing methods for manufacturing worm reducers face challenges in improving assembling workability due to the obstruction of the coil spring during the insertion of the worm shaft, which complicates the assembly process and increases the number of components required.

Innovation Solution

A method involving an elastic member urging the worm shaft housed in a housing toward a worm wheel, with specific steps including arranging the elastic member in a recess, inserting a jig to compress it, inserting the worm shaft, and removing the jig, facilitating smoother assembly by compressing the elastic member before worm shaft insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the coil spring is arranged in the coil spring housing portion before inserting the worm shaft, then the elastic member can urge the worm shaft toward the worm wheel, but the coil spring obstructs the insertion of the worm shaft into the worm shaft housing portion

Engineering Contradiction:

Improvebacklash reductionVSAvoidassembling workability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The coil spring is compressed in advance using a compression tool before the worm shaft is inserted. This preliminary compression action allows the spring to be installed in the housing without obstructing the worm shaft insertion, as the spring is already in a compact state that fits within the available space during assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A compression tool is used as an intermediary device to compress the coil spring during assembly. This tool allows the spring to be temporarily compressed to a smaller volume, enabling it to be positioned in the housing without blocking the worm shaft insertion path, and then released to provide the necessary urging force.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the coil spring housing portion does not communicate with the outside of the housing, then the number of components can be reduced by eliminating the cap, but the coil spring cannot be inserted into the coil spring housing portion afterwards

Engineering Contradiction:

Improvenumber of componentsVSAvoidassembling process

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The coil spring is compressed in advance using a compression tool before the worm shaft is inserted. This preliminary compression action allows the spring to be installed in the housing without obstructing the worm shaft insertion, as the spring is already in a compact state that fits within the available space during assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A compression tool is used as an intermediary device to compress the coil spring during assembly. This tool allows the spring to be temporarily compressed to a smaller volume, enabling it to be positioned in the housing without blocking the worm shaft insertion path, and then released to provide the necessary urging force.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the worm shaft is inserted into the worm shaft housing portion after the coil spring is arranged, then the coil spring can be positioned correctly, but a part of the coil spring is located in the worm shaft housing portion and obstructs the insertion

Engineering Contradiction:

Improvecoil spring positioningVSAvoidworm shaft insertion

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The coil spring is compressed in advance using a compression tool before the worm shaft is inserted. This preliminary compression action allows the spring to be installed in the housing without obstructing the worm shaft insertion, as the spring is already in a compact state that fits within the available space during assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A compression tool is used as an intermediary device to compress the coil spring during assembly. This tool allows the spring to be temporarily compressed to a smaller volume, enabling it to be positioned in the housing without blocking the worm shaft insertion path, and then released to provide the necessary urging force.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach enhances the assembling workability of the worm reducer by allowing the worm shaft to be inserted without obstruction from the elastic member, reducing the complexity of the assembly process and potentially reducing the number of components needed.

Implementation Method 1

the coil spring is elastically deformed by being sandwiched between the cap and the worm shaft, thereby urging the worm shaft toward the worm wheel

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

inserting a jig to compress it

Methodology Applied

Scientific EffectMechanical compression: Compression

Data Source

PatentEP3376070B1Method for manufacturing worm reducer, worm reducer and electric power steering system

Publication Date: 2020.01.29 JTEKT CORP

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AI summary

In a worm reducer, an elastic member urges a worm shaft housed in a housing toward a worm wheel. In a method for manufacturing the worm reducer, the elastic member is arranged in a recess formed on the inner face of the housing. Then, a jig is inserted into the housing, and the elastic member is compressed by the jig. In the state in which the elastic member is compressed by the jig, the worm shaft is inserted into the housing. Then, the jig is removed from the housing.