Spline-Coupled Motor Transmission Shaft Positioning Without Recess Machining

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Solution Overview

Problem

The machining of the bottom surface of the recess in the motor shaft of a hydraulic motor for positioning the input shaft of the planetary speed reduction mechanism is complicated and increases manufacturing costs.

Innovation Solution

The motor shaft and drive shaft are connected using a spline coupling with a snap ring on the outer periphery of the drive shaft, eliminating the need for precise machining of the bottom surface of the recess and allowing for easier assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the bottom surface of the recess is precisely machined to ensure positioning accuracy, then the positioning accuracy of the input shaft and motor shaft is improved, but the manufacturing complexity and cost increase

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

A positioning ring is introduced as an intermediary component between the input shaft and the recess. The positioning ring has an outer circumference that fits into the recess and an inner circumference that fits onto the input shaft, mediating the positioning function and eliminating the need for complex recess machining.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The positioning function is segmented from the recess structure and transferred to a separate positioning ring component. This allows the recess to be simply formed without precise machining, while the positioning ring can be manufactured separately with standard precision processes.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If the bottom surface of the recess is precisely machined, then the positioning accuracy is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The positioning ring serves as a mediator that separates the positioning function from the expensive recess machining process, allowing both components to be manufactured using simpler, less costly processes while maintaining high positioning accuracy through the ring's precision fit.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The positioning ring can be manufactured as a relatively simple, cost-effective component compared to precision-machining the recess, providing an economical solution for achieving accurate positioning without high manufacturing costs.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Manufacturing precision

If a tool is inserted into the recess to perform machining, then the positioning accuracy is improved, but the device complexity and manufacturing process complexity increase

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmachining process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The positioning ring mediates between the simple recess formation process and the input shaft positioning requirement, eliminating the need for complex tool insertion and machining operations within the recess while ensuring accurate positioning through the ring's geometry.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4184004B1Motor with transmission
Publication Date: 2025.11.12 KYB CORP
  • EP4184004B1 patent drawingFigure 1
  • EP4184004B1 patent drawingFigure 2
  • EP4184004B1 patent drawingFigure 3

AI summary

In a transmission-equipped motor 100, a spline portion 32 is formed at an end portion of a drive shaft 31 of a transmission 30, and a spline hole 22 with which the spline portion 32 is engaged is formed on an end surface of a motor shaft 21 of a hydraulic motor 20. A snap ring 33 which contacts an end surface 21a of the motor shaft 21 having the spline hole 22 is provided on an outer periphery of the drive shaft 31 having the spline portion 32 so that the snap ring 33 positions the motor shaft 21 and the drive shaft 31.