Double-Helical Gear Bearing Layout for Axial Alignment Stability

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Solution Overview

Problem

In power transmission mechanisms with multiple double-helical gears on the same axis, axial behaviors of individual gears interfere, hindering their aligning effects and leading to increased vibrations and noise.

Innovation Solution

The use of a second bearing with greater axial rigidity and a smaller axial internal gap compared to first and third bearings, allowing the first and fourth double-helical gears to move more easily in the axial direction, thereby minimizing interference between the second and third double-helical gears on the same shaft.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multiple double-helical gears are provided on the same axis, then the power transmission capability is improved, but the axial behaviors of the gears interfere with each other, hindering their aligning effects

Engineering Contradiction:
Improvepower transmission capabilityVSAvoidaligning effect
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent applies different axial rigidities to different bearings supporting the same shaft. Specifically, the second bearing (supporting multiple double-helical gears) is designed with greater axial rigidity than the first and third bearings (each supporting single gears). This local differentiation in bearing properties allows the system to accommodate multiple gears on the same axis while preventing harmful interference between their axial behaviors, thus maintaining the aligning effect of each gear pair.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If the second bearing has greater axial rigidity, then the axial displacement of the second double-helical gear is reduced, but the first and fourth gears can move more easily in the axial direction to achieve aligning effect

Engineering Contradiction:
Improveaxial position stabilityVSAvoidaxial movement capability
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent implements local quality by assigning different axial rigidities to different bearings based on their specific functional requirements. The second bearing, supporting multiple gears that would interfere with each other, is given high axial rigidity to stabilize their positions. In contrast, the first and third bearings supporting single gears are designed with lower axial rigidity, allowing these gears to move axially to achieve proper mesh alignment. This localized differentiation resolves the contradiction between stability and ease of operation.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies partial action by providing axial movement capability only where needed (at the first and third bearings supporting single gears), while maintaining rigidity where interference would occur (at the second bearing supporting multiple gears). This selective application of flexibility versus rigidity optimizes the system performance by allowing aligning movement only for gears that require it.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3327313B1Power transmission mechanism
Publication Date: 2021.02.24 TOYOTA JIDOSHA KK
  • EP3327313B1 patent drawingFigure 1
  • EP3327313B1 patent drawingFigure 2
  • EP3327313B1 patent drawingFigure 3

AI summary

With respect to a relation between an amount of axial displacement of a first bearing (4) as well as an amount of axial displacement of a second bearing (5) relative to an axial force generated at a meshing part (2a) between a first double-helical gear (11) and a second double-helical gear (22), and an amount of axial displacement of the second bearing (5) as well as an amount of axial displacement of a third bearing (6) relative to an axial force generated at a meshing part (3a) between a third double-helical gear (23) and a fourth double-helical gear (34), the second bearing (5) is configured to have a smaller amount of axial displacement than that of at least one of the first bearing (4) and the third bearing (6).