Gearshift Rod Interlock to Prevent Forbidden Gear Positions
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Solution Overview
Problem
Existing gearshift arrangements in vehicle transmissions are prone to unintentional shifting into unwanted states, leading to reliability issues and potential mechanical failures.
Innovation Solution
A gearshift arrangement with a mechanical structure that prevents shifting into forbidden gear positions by using aligned shift rods and pistons, which are configured to abut and move independently, and are actuated by fluid pressure to ensure precise control and avoid unwanted gear positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gearshift arrangements are used, then the structure is simple and cost-effective, but the reliability is poor due to unintentional shifting into unwanted states
Solution Approach 1:
The patent applies preliminary anti-action by configuring the shift rods and shift forks with abutment features that prevent unintentional gear shifts before they can occur. The abutment between shift rods and the abutment between shift forks create mechanical constraints that counteract unintended movement, thereby preventing harmful shifting events in advance.
Solution Approach 2:
The patent implements preliminary action through the deliberate positioning and configuration of shift rods and shift forks during the gearshift mechanism design. The abutment features are pre-positioned to ensure that when shift forks engage with gearwheels, the shift rods are already in positions that prevent movement into forbidden gear states, preparing the system in advance to avoid unwanted shifts.
2Reliability
If mechanical constraints are added to prevent forbidden gear positions, then the reliability improves, but the device complexity increases
Solution Approach 1:
The patent merges the prevention function into the existing shift rod and shift fork components. Rather than adding separate constraint mechanisms, the abutment features are integrated directly into the shift rods and shift forks themselves, combining the shifting function with the prevention function in the same components, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The shift rods and shift forks are designed to perform multiple functions: they control gearwheel engagement while simultaneously preventing movement into forbidden gear positions through their abutment features. This multi-functionality reduces the need for additional dedicated constraint components, thereby limiting the increase in device complexity while improving reliability.
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 provides a robust and reliable gearshift arrangement that prevents unintended gear shifts, enhancing mechanical stability and reliability while maintaining a cost-effective design.
Implementation Method 1
the first and second shift rods are configured to abut, such that movement to a forbidden gear position is prevented
Implementation Method 2
a first shift fork first position in which the first gearwheel is locked to a first element by the first shift fork
Implementation Method 3
actuated by fluid pressure to ensure precise control and avoid unwanted gear positions
Data Source
AI summary
A gearshift arrangement has a housing, a first gearwheel and a second gearwheel, a first shift fork and a second shift fork, a first shift rod and a second shift rod, configured to move the first shift fork and the second shift fork, respectively. The first and second shift rods are configured to abut, such that movement to a forbidden gear position is prevented, wherein the forbidden gear position comprises the first shift fork and the second shift fork simultaneously being in the first shift fork first position and the second shift fork first position.