Gear Coupling Guide Rod Structure for Low-Friction Shifting

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Solution Overview

Problem

Existing coupling devices in electric drive systems experience unwanted residual torque and frictional forces during gear engagement and disengagement, leading to inefficiencies and potential mechanical stress.

Innovation Solution

A gearbox with a coupling device featuring a shift fork and guide rod system, where the shift fork is coupled to a guide rod with sliding bushings and stop sleeves, allowing precise, low-friction guidance and limiting movement to axial directions, using an electromechanical actuator with a spindle for rotationally controlled gear engagement and disengagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the shift fork is guided by a guide rod with sliding bushings, then the guidance precision and movement control are improved, but the device complexity increases due to additional components

Engineering Contradiction:
Improveguidance precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The sliding bushings are integrated into the guide rod structure, with the stop sleeves nested on the guide rod between the shift fork and sliding bushings. This nested arrangement provides precise guidance functionality while minimizing the number of separate components, thereby reducing overall device complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Manufacturing precision

If stop sleeves are added to limit guide rod movement, then the movement control and positioning accuracy are improved, but the manufacturing complexity increases

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

Solution Approach 1:

The stop sleeves are merged with the guide rod as integral components, where the stop sleeves are directly formed on the guide rod body. This integration eliminates the need for separate stop components and simplifies the manufacturing process while maintaining precise positioning control.

Inventive Principle:
Principle #5Merging (Combining)

3Stability of the object's composition

If the shift fork is rigidly connected to the guide rod, then the structural stability is improved, but the frictional forces and mechanical stress increase

Engineering Contradiction:
Improvestructural stabilityVSAvoidfrictional forces
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The sliding bushings act as intermediary elements between the guide rod and the shift fork assembly. These bushings provide a low-friction interface that allows the rigid connection to maintain structural stability while minimizing harmful frictional forces through the intermediate bearing surface.

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

The solution provides precise and low-friction gear coupling and decoupling, minimizing unwanted torque and frictional forces, resulting in a structurally simple and stable drive system.

Implementation Method 1

low-friction guidance

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

sliding bushings

Methodology Applied
Scientific EffectSliding: Lubrication

Implementation Method 3

electromechanical actuator with a spindle

Methodology Applied
Scientific EffectElectromechanical conversion: Electromagnetic Induction

Implementation Method 4

limit the movement of the guide rod

Methodology Applied
Scientific EffectMechanical constraint: Mechanical Force

Data Source

PatentEP4248110B1Transmission with a coupling device for coupling and/or uncoupling a gearwheel to or from a shaft
Publication Date: 2026.04.22 ROBERT BOSCH GMBH
  • EP4248110B1 patent drawingFigure 1
  • EP4248110B1 patent drawingFigure 2

AI summary

The invention relates to a coupling device (10) for coupling and/or uncoupling a gearwheel (21) to or from a shaft (14) and to a transmission, in particular for an electrical drive assembly, comprising a corresponding coupling device (10).