Vehicle Transmission Shift Locking Against Double Meshing
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Solution Overview
Problem
Existing vehicle transmission systems face challenges in preventing double meshing during gear changes, particularly when the shifting mechanism accidentally rotates in the downshift direction due to actuator failures or electronic control unit malfunctions, leading to torque interruption and potential damage.
Innovation Solution
Incorporating a double-meshing preventing mechanism that includes a ratchet tooth and stopper member, which can switch between a one-way state to prevent downshift movement and a free state to allow both upshift and downshift movements, ensuring the switching mechanisms do not mesh incorrectly, and a detent mechanism to maintain the ratchet tooth and stopper member in contact, interrupting power transmission when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shifting mechanism is provided to move switching mechanisms during gear changes, then gear changing capability is improved, but the risk of accidental downshift rotation causing double meshing increases
Solution Approach 1:
The ratchet tooth and stopper member are positioned in advance to prevent accidental downshift rotation before it can cause double meshing. The one-way clutch mechanism is pre-configured to engage and block rotational movement in the harmful direction, counteracting potential actuator failures or control unit malfunctions before they result in double meshing
Solution Approach 2:
The ratchet tooth and stopper member act as an intermediary mechanical constraint between the shifting mechanism and the switching mechanisms. This intermediary component mediates the rotational movement, allowing intentional gear changes while blocking accidental downshift rotation that would cause double meshing
2Reliability
If a ratchet tooth and stopper member are added to prevent accidental downshift, then reliability is improved, but device complexity increases
Solution Approach 1:
The one-way clutch mechanism is designed to function automatically without external control. When accidental downshift rotation occurs, the ratchet tooth and stopper member self-engage through mechanical interaction, blocking the harmful rotation without requiring sensors, actuators, or electronic control systems
Solution Approach 2:
The ratchet tooth and stopper member constitute a simple, inexpensive mechanical safeguard that can be integrated into the existing shifting mechanism structure. This low-cost component provides reliable protection against double meshing without adding significant complexity or cost to the transmission system
3Productivity
If switching mechanisms are moved in axial direction to change gears, then gear transition is achieved, but torque interruption may occur during transition
Solution Approach 1:
The ratchet tooth and stopper member are positioned and configured in advance to engage before the switching mechanisms complete their axial movement. This preliminary action ensures that if accidental downshift rotation occurs during the transition period, the one-way clutch mechanism is already in place to prevent double meshing and torque interruption
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
Effectively prevents double meshing and torque interruption by ensuring the switching mechanisms operate correctly, even in the event of actuator failures or malfunctions, thereby enhancing transmission reliability and preventing damage.
Implementation Method 1
springs that are interposed between the first ring and the second ring and exert an urging force in a direction in which these rings are drawn toward each other
Implementation Method 2
a double-meshing preventing mechanism that includes a ratchet tooth and stopper member, which can switch between a one-way state to prevent downshift movement and a free state to allow both upshift and downshift movements
Implementation Method 3
gear-side meshing teeth formed in the speed-changing gear and meshing teeth formed in the switching mechanism mesh with each other, causing the shaft and the speed-changing gear to rotate integrally
Data Source
AI summary
A vehicle transmission includes a shaft; speed-changing gears; switching mechanisms; and a shifting mechanism. The shifting mechanism is provided with a double-meshing preventing mechanism configured to switch between a one-way state in which the switching mechanisms are hindered from moving in a downshift direction and allowed to move in an upshift direction and a free state in which the switching mechanisms are allowed to move in both the downshift direction and the upshift direction.