Vehicle Transmission Shifting Mechanism With Double-Meshing Prevention
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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
Incorporation of a double-meshing preventing mechanism that includes a ratchet tooth and stopper member, allowing the system to switch between a one-way state to prevent downshift movement and a free state for normal operation, ensuring the switching mechanisms only move in the upshift direction when necessary, thereby preventing double meshing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the shifting mechanism is designed to allow bidirectional rotation for normal upshift and downshift operations, then the transmission can perform normal gear changes, but the system becomes vulnerable to accidental downshift rotation causing double meshing when actuators or control units fail
Solution Approach 1:
The patent applies preliminary anti-action by introducing a ratchet tooth and stopper member that preemptively prevent accidental downshift rotation before double meshing can occur. The ratchet mechanism is designed to engage and block rotation in the downshift direction when the transmission is in an upshifted state, countering potential harmful rotation before it causes damage. This allows the system to maintain bidirectional operation for normal use while having a pre-configured protective mechanism against failure modes.
2Reliability
If a ratchet tooth and stopper member are added to prevent accidental downshift rotation, then protection against double meshing is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the ratchet tooth and stopper member to serve multiple functions: they prevent accidental downshift rotation, provide mechanical feedback for control system monitoring, and can be integrated with existing shifting fork structures. The stopper member can be positioned to engage with the ratchet tooth in specific gear states, allowing a single component arrangement to provide protection across multiple gear stages without requiring separate mechanisms for each gear.
3Ease of operation
If the system allows free rotation in both directions for normal operation, then ease of operation is maintained, but torque interruption and damage can occur during accidental downshift movements
Solution Approach 1:
The patent applies the intermediary principle by introducing the ratchet tooth and stopper member as mediating elements between the shifting mechanism and the potential harmful effect of accidental downshift. The ratchet mechanism acts as an intermediary that allows normal bidirectional operation but intercepts and blocks harmful rotation, preventing torque interruption and damage. The stopper member serves as a mediator that can be positioned to engage with the ratchet tooth, providing a controlled barrier against accidental downshift while maintaining ease of normal operation.
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 double-meshing preventing mechanism effectively prevents torque interruption and damage by ensuring the switching mechanisms do not engage in double meshing, even during accidental downshift movements, allowing for safe and reliable gear changes.
Implementation Method 1
a ratchet tooth and stopper member, allowing the system to switch between a one-way state to prevent downshift movement and a free state for normal operation
Implementation Method 2
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
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.