Segmented Dog Clutch Tooth Geometry for Low-Force Meshing
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Solution Overview
Problem
Dog clutches in the automotive industry face issues with high actuation force leading to noise and premature wear when tangential tolerance is small, and excessive noise and vibrations when tolerance is large, making it difficult to achieve safe meshing with low noise and small actuation force.
Innovation Solution
The pulling side of the tooth is shaped with distinct portions, where the first and third portions are parallel to the generating line, tapering towards the vertex, and the second portion joins these, allowing for a small tolerance and reduced actuation force, with the sleeve having straight sides and the crown having a tapered pulling side to manage reaction forces and synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tangential tolerance between the teeth of the crown and the sleeve is very small, then the clutch meshing is safe and reliable, but a great actuation force needs to be applied which causes high clutch noise and premature wear
Solution Approach 1:
The pulling side of the tooth is segmented into three distinct portions (first, second, and third portions) with different geometries. The first portion has a smaller pitch for reliable meshing, the second portion provides a transition zone, and the third portion has a larger pitch to reduce actuation force. This segmentation allows the tooth to simultaneously achieve both small tolerance for reliability and reduced actuation force.
Solution Approach 2:
Different portions of the tooth pulling side are given different local qualities: the first portion (near the base) has a smaller pitch for secure engagement, while the third portion (near the vertex) has a larger pitch for easier actuation. This local differentiation allows each region to optimize for its specific function, resolving the contradiction between meshing safety and actuation force.
2Force
If the tangential tolerance between the teeth is greater, then a smaller clutch actuation force is needed with better acoustic comfort, but the torque transferred through the clutch is close to zero and the clutch generates continuous noise and vibrations
Solution Approach 1:
The tooth geometry is segmented into portions with different pitches. The first portion maintains a smaller pitch to ensure adequate torque transfer capability and prevent excessive clearance, while the third portion has a larger pitch to reduce actuation force. This segmentation enables the clutch to achieve both low actuation force and sufficient torque transfer.
Solution Approach 2:
The pulling side exhibits local quality variations where the first portion (base area) has smaller pitch for torque transfer integrity, and the third portion (vertex area) has larger pitch for reduced actuation force. This local differentiation resolves the contradiction by allowing each region to optimize for its primary function.
3Reliability
If the tangential tolerance is small, then the clutch meshing is secure, but the teeth experience continuous bouncing and premature wear due to excessive actuation force
Solution Approach 1:
The tooth is segmented into three portions where the first portion ensures secure meshing while the third portion reduces actuation force. This segmentation prevents the excessive forces that cause bouncing and wear, extending teeth service life while maintaining meshing security.
Solution Approach 2:
Different local qualities are assigned to different portions of the tooth: the first portion provides secure engagement with smaller pitch, while the third portion reduces actuation force with larger pitch. This local differentiation eliminates the continuous bouncing and premature wear while maintaining reliable meshing.
Data Source
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AI summary
A dog clutch comprising a sleeve (M) and a relative crown (K) with respective teeth (TM1, TM2, TK1, TK2) conformed for engaging each one alternatively to the others wherein, during operation a pulling side (A) for said teeth is defined, that identifies a surface through which the torque is transferred, and wherein the teeth pulling side (A) or at least the crown and/or the sleeve is conformed so that the relative tooth is tapered from a relative base (BA) towards a relative vertex (VA), wherein said pulling side comprises at least three portions (A1, A2, A3) of which a first portion is adjacent to said base (BA) and a third portion is adjacent to said vertex (VA) following a rectilinear path and being approximately parallel to a generating line (GEN) of said crown or sleeve, and having a second portion (A2) adjoining said first portion with said third portion.