Gear Pair Pitch Offset for Lower Wear and Noise
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Solution Overview
Problem
Existing gear pairs in transmissions face issues with manufacturing deviations in normal meshing pitches and pressure angles, leading to wear and noise excitation, as they are designed with identical target pitches to ensure trouble-free operation.
Innovation Solution
A gear pair is designed with a first, relatively inelastic gear and a second, relatively elastic gear, having different target normal meshing pitches and pressure angles, with the inelastic gear having a smaller pitch and larger pressure angle, reducing wear and noise excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gears in a gear pair have identical standard engagement pitches to ensure smooth operation and engagement, then operational reliability is improved, but wear and noise excitation increase due to manufacturing deviations accumulating
Solution Approach 1:
The patent applies parameter changes by deliberately specifying different nominal normal engagement pitches for the first and second gears in a gear pair. Instead of using identical engagement pitches as in conventional designs, the invention introduces a controlled deviation between the engagement pitch of the first gear and the second gear. This parameter change compensates for manufacturing deviations and material elasticity differences, reducing wear and noise while maintaining reliable operation.
2Ease of manufacture
If gears are made with identical nominal engagement pitches specified for manufacturing, then manufacturing precision is simplified, but actual engagement precision deteriorates due to material elasticity differences and manufacturing tolerances
Solution Approach 1:
The patent applies local quality by differentiating the engagement pitch specification between the two gears in the pair based on their material properties. The first gear (more elastic material) is assigned a different nominal normal engagement pitch than the second gear (less elastic material). This localized differentiation in design parameters compensates for the inherent material elasticity differences, ensuring that each gear's actual engagement pitch accounts for its specific material characteristics, thereby improving overall engagement precision.
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 effectively reduces wear on the elastic gear and minimizes noise excitation by allowing greater deviations in target pitches and pressure angles than those caused by manufacturing deviations, ensuring optimal engagement with reduced wear and noise.
Implementation Method 1
the first gear (11) made of a relatively inelastic material, in particular a metallic material, and a second gear (12) made of a relatively elastic material, in particular a plastic
Data Source
Figure 1
AI summary
The invention relates to a gear pair (10) of a gearbox, comprising a first gear (11) and a second gear (12) engaged with the first gear (11), wherein the first gear (11) is manufactured from a less elastic or less soft material compared to the second gear (12), and wherein the first gear (11) and the second gear (12) have different target normal base pitches.