Gearbox Fork Shaft Interlock With Cam-Lever Neutral Locking
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Solution Overview
Problem
Existing gearbox systems lack a robust mechanical interlocking mechanism to prevent simultaneous changes in combustion engine and electric gear ratios, which is essential for safe and efficient operation in hybrid drive vehicles.
Innovation Solution
A mechanical interlocking system comprising pivoting levers with eccentric cam profiles and a locking pin, which aligns with notches on opposing levers to lock them in neutral positions, ensuring that only one ratio can be changed at a time, utilizing rotary actuators to drive the levers and an interlocking rocker to maintain the locking mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical interlocking system is implemented to prevent simultaneous gear ratio changes, then safety and operational reliability are improved, but device complexity increases due to additional levers, cams, and locking mechanisms
Solution Approach 1:
The interlocking function is merged with the existing gear ratio change mechanism by integrating the locking pin and cam profiles directly into the lever assembly. The locking pin is positioned to interact with notches on both levers simultaneously, combining the interlocking function with the existing lever-cam-finger mechanism rather than adding a completely separate system.
Solution Approach 2:
The locking pin acts as an intermediary element that mediates between the two levers. When one lever is actuated, the locking pin engages with the cam profile and prevents the other lever from moving, serving as a mechanical mediator that enforces the interlocking constraint without requiring complex control logic.
2Reliability
If a mechanical interlocking system with locking pin and cam profiles is added, then interlocking reliability is improved, but manufacturing complexity and precision requirements increase
Solution Approach 1:
The cam profiles are designed with specific geometric parameters (convex circular arcs centered on the lever axis) that standardize the manufacturing process. By defining the cam profile geometry in terms of simple circular arcs rather than complex custom curves, the manufacturing precision requirements are reduced while maintaining reliable interlocking functionality.
3Reliability
If the locking pin is positioned to engage both notches simultaneously, then interlocking effectiveness is improved, but alignment precision requirements increase
Solution Approach 1:
The locking pin is positioned asymmetrically relative to the two levers, engaging with the cam profiles at different points in their rotation cycles. This asymmetric positioning allows the locking pin to effectively lock one lever while the other is being actuated, reducing the need for perfect symmetric alignment between the two notches.
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 system effectively prevents simultaneous changes in gear ratios, enhancing safety and operational efficiency by ensuring that either the combustion engine or electric motor ratios can be changed independently, while being easily integratable into existing gearbox assemblies.
Implementation Method 1
bears a first eccentric cam, the cam profile of which has a first notch for locking the first lever in its neutral position
Implementation Method 2
in relation to an intermediate angular position of rest toward which the interlocking rocker is elastically returned
Data Source
AI summary
An assembly actuates two fork shafts of a gearbox which includes two rotating actuators and a system for interlocking with a first lever which supports a drive finger of a first fork and a cam the profile of which comprises a notch for locking the first lever; a second lever which supports a drive finger of a second fork and a cam the profile of which comprises a second notch for locking the second lever; and a pivoting interlocking rocker which supports a locking pin that is able to interact with one or other of the two locking notches in order to angularly lock the associated lever when the other lever is actuated in order to engage a gear ratio.