Reverse Inhibitor Mechanism Assembly and Compactness

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Solution Overview

Problem

The existing reverse inhibitor mechanisms for automatic transmissions face challenges in assembly workability and compactness, with unstable temporary assembled states and enlarged shift drum sizes due to the external positioning of the reverse inhibitor arm and groove.

Innovation Solution

A reverse inhibitor mechanism where the shift drum is journaled to a side wall for rotational support, with a reverse inhibitor arm detachably engaged with a groove on the shift drum's outer surface, and a reverse inhibitor shaft with a larger diameter at one end for improved assembly and weight reduction, allowing the arm to be assembled from within the transmission case and maintained by a torsion spring for engagement with the groove.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the reverse inhibitor arm and groove are positioned externally on the shift drum, then the reverse inhibitor mechanism can be assembled, but the shift drum size is enlarged

Engineering Contradiction:

Improveassembly workabilityVSAvoidshift drum size

Core Design Contradiction:

Ease of manufactureVSVolume of moving object

Solution Approach 1:

The reverse inhibitor arm is positioned inside the transmission case rather than externally, nesting the mechanism within the existing space. The arm is journaled to the rear side wall inside the case, and the groove is formed on the inner circumferential surface of the shift drum, eliminating the need for external positioning and reducing the shift drum size.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Ease of manufacture

If the reverse inhibitor shaft is assembled from the outside with one end journaled first, then assembly can proceed, but the temporary assembled state is unstable and the shaft may fall off

Engineering Contradiction:

Improveassembly processVSAvoidassembly stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The assembly process is inverted by assembling the reverse inhibitor shaft and arm from inside the transmission case rather than from the outside. The shaft is inserted through the rear side wall from the interior, and the arm is positioned to engage the groove before the rear case cover is installed, eliminating the unstable temporary state and potential for the shaft to fall off.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If the reverse inhibitor shaft has uniform diameter, then manufacturing is simple, but weight reduction is limited

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidshaft weight

Core Design Contradiction:

Ease of manufactureVSWeight of moving object

Solution Approach 1:

The reverse inhibitor shaft has different diameters at different locations: a larger diameter at the first end portion for fitting the reverse inhibitor arm and a smaller diameter at the second end portion for journaling. This non-uniform diameter distribution reduces the overall weight of the shaft while maintaining the necessary structural integrity and fit at each location.

Inventive Principle:

Principle #3Local quality

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 design enhances assembly workability by eliminating unstable states and reduces the shift drum size, improving the compactness and stability of the reverse inhibitor mechanism.

Implementation Method 1

A reverse inhibitor arm is urged by a torsion spring towards the outer circumferential surface of the shift drum

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8191443B2Reverse inhibitor mechanism for regulating automatic transmission gear shifting, and method of assembling same

Publication Date: 2012.06.05 HONDA MOTOR CO LTD

AI summary

A reverse inhibitor mechanism for a transmission of an all terrain vehicle, in which a shift drum is jounalled to a side wall opposite the transmission case so as to be rotatably supported thereon, and a reverse inhibitor arm is detachably engaged with the reverse inhibitor groove formed in the outer circumferential surface of the shift drum to regulate a reverse setting. A reverse inhibitor shaft having the reverse inhibitor arm supported at one end thereof is positioned within the transmission case. The other end of the reverse inhibitor shaft is rotatably journaled to one of the opposite side walls of the transmission case from the inside of the transmission case. A distal end of the reverse inhibitor arm which swings by the rotation of the reverse inhibitor shaft is brought into engagement with the reverse inhibitor groove during assembly of the reverse inhibitor mechanism.