Gear Tooth Face Geometry for Low-Noise Transmission Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing transmissions require high mechanical strength and large actuators due to inefficient disengagement mechanisms, leading to abnormal noise and increased kinetic energy during shifts.
Innovation Solution
The transmission design includes specific angle configurations between planes and faces of gears and movable members to reduce thrust forces, allowing for smaller actuators and reduced mechanical strength, minimizing noise and kinetic energy during shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large angle is formed between the plane including the shaft and the guide surface, then the disengagement of teeth is facilitated during upshift, but a large-sized actuator is required to move the movable member against the thrust force during downshift
Solution Approach 1:
The guide surface is divided into two distinct portions: a first portion that facilitates disengagement during upshift, and a second portion that reduces thrust force during downshift. This segmentation allows each portion to optimize for its specific function, resolving the contradiction between disengagement ease and actuator size.
Solution Approach 2:
Different regions of the guide surface are given different angular characteristics. The first portion has a larger angle for easy disengagement, while the second portion has a smaller angle to reduce thrust force. This local differentiation of geometric properties enables the guide surface to serve multiple functions with conflicting requirements.
2Volume of moving object
If a small angle is formed between the plane including the shaft and the guide surface, then the actuator size is reduced, but the mechanical strength required for members and immobilization mechanism increases
Solution Approach 1:
The guide surface is segmented into portions with different angles, allowing the second portion to have a small angle for reduced actuator size while the first portion maintains a larger angle to facilitate disengagement without requiring excessive mechanical strength.
Solution Approach 2:
The angular parameter of the guide surface is varied across different portions. By changing the angle parameter from large in the first portion to small in the second portion, the patent optimizes both actuator size and mechanical strength requirements for different operational phases.
3Stability of the object's composition
If the movable member is immobilized after disengagement, then positioning stability is improved, but abnormal noise occurs due to high kinetic energy
Solution Approach 1:
The guide surface is designed to reduce the kinetic energy of the movable member before it reaches the immobilization position. By facilitating smooth disengagement and reducing impact energy in advance, the patent prevents abnormal noise during immobilization while maintaining positioning stability.
Solution Approach 2:
The thrust force that initially causes concern for mechanical strength requirements is converted into a beneficial effect. The guide surface utilizes the thrust force direction to facilitate controlled disengagement and energy dissipation, transforming what could be a harmful impact into a controlled energy reduction mechanism that prevents noise.
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
The present invention provides a transmission that achieves required mechanical strength, reduced abnormal noise, and a reduction in size of an actuator for moving a movable member. The transmission is configured such that a gear (24) having first teeth (32) and disposed on a shaft is selectively coupled to the shaft, and includes a movable member (34) having second teeth (35) that mesh with the first teeth. A second face (57) of a first tooth and a fourth face (64) of a second tooth facing the second face include third sections (58, 65), fourth sections (59,66) adjoining the tooth-tip sides of the third sections, and fifth sections (60, 67) adjoining the tooth-tip sides of the fourth sections. The angle Θ1 formed between a plane (P) including the shaft and the third section and the angle Θ2 formed between the plane and the fifth section are smaller than the angle Θ3 formed between the plane and the fourth section.