Gearshift Lever Stepped-Track Lock for Reverse Gear Selection

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Solution Overview

Problem

Existing mechanical gearboxes with reverse gear locking systems are complex, unreliable, and prone to accidental engagement of reverse gear when drivers mistake it for sixth gear, due to the complexity and number of components.

Innovation Solution

A control lever with a pivoting articulation and a movable finger that engages in a stepped track, prohibiting finger movement when selecting fifth gear, thus preventing accidental reverse gear engagement, and featuring a trigger-actuated mechanism to allow reverse gear pivoting only when the lever is in the neutral position between fifth and reverse gear corridors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a trigger mechanism is added to allow reverse gear engagement, then reverse gear can be engaged when needed, but the device complexity increases and the trigger can be accidentally pulled when in fifth gear position

Engineering Contradiction:
Improvereverse gear engagementVSAvoidtrigger mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The lever is divided into two independent but coordinated components: a lever body for gear selection and a movable finger for reverse gear control. The finger can move independently along the lever, engaging with the stepped track at specific positions. This segmentation allows the reverse gear function to be separated from the main gear selection mechanism, reducing the complexity of the overall system while maintaining safety.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The movable finger is pre-positioned to engage with the stepped track at the neutral position between fifth gear and reverse gear corridors. Before reverse gear can be engaged, the finger must first be moved along the lever to a specific position, which is a preliminary action that ensures the lever is in the correct position. This preliminary action prevents accidental engagement while allowing intentional reverse gear selection.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the lever design allows direct pivoting to reverse gear, then gear selection is simple, but accidental engagement occurs when drivers mistake reverse for sixth gear

Engineering Contradiction:
Improvegear selectionVSAvoidaccidental reverse engagement prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The stepped track is designed with a specific geometry that creates a preliminary barrier to reverse gear engagement. The track includes a first portion that the finger follows when the lever is in the neutral position, and a second portion that requires the finger to be moved along the lever to a specific position before engagement can occur. This preliminary anti-action prevents drivers from accidentally engaging reverse gear by simply pivoting the lever, as the finger must first be positioned correctly along the lever.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The movable finger acts as an intermediary element between the lever and the reverse gear mechanism. Instead of the lever directly engaging reverse gear, the finger must first be moved along the lever to a specific position, then it can engage with the appropriate portion of the stepped track. This intermediary action adds a safety step that prevents accidental engagement while maintaining ease of operation for intentional reverse gear selection.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a complex trigger cable system is used to unlock reverse gear, then reverse gear locking is achieved, but the number of parts increases and reliability decreases

Engineering Contradiction:
Improvereverse gear lockingVSAvoidnumber of parts
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The reverse gear locking function is merged with the existing lever and finger mechanism. Instead of adding a separate trigger cable system with multiple parts, the invention integrates the locking function into the lever itself through the movable finger and stepped track. The finger's movement along the lever and engagement with the stepped track combines the gear selection and reverse gear locking functions into a single integrated mechanism, reducing the number of parts while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The lever system is designed to be self-regulating for reverse gear engagement. The movable finger automatically engages with the stepped track at the correct position based on the lever's position, and the geometry of the stepped track itself provides the locking and unlocking mechanism. No external trigger cable or additional actuating mechanism is needed - the system uses its own components (lever, finger, stepped track) to achieve the reverse gear locking function, eliminating the need for complex external systems.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3434936B1Lever for controlling a mechanical gearbox with system for locking the reverse gear
Publication Date: 2021.04.14 DURA AUTOMOTIVE HLDG U K LTD
  • EP3434936B1 patent drawingFigure 1~4
  • EP3434936B1 patent drawingFigure 5~8

AI summary

Control lever (1) mounted pivoting about a joint (3) in a five-speed mechanical gearbox (2) of a motor vehicle, of which a reverse gear is located in the same channel as a fifth gear.According to the invention, the lever (1) includes a finger (5) disposed between the joint (3) and an opposite end of the lever (1), the finger (5) being intended to engage in a slot (6) when said lever (1) is pivoted to select the fifth gear and reverse gear slot, the finger (5) is movable along the lever (1) and the slot (6) defines a stepped track (6a) allowing: - either the pivoting of the lever (1) to pass the fifth gear corresponding to a stop position of the finger (5) in which the movement of the finger (5) along the lever (1) is prohibited; - or the movement of the finger (5) along the lever (1) to allow the finger (5) to pass the step (7) of the track (6a) and allow the pivoting of the lever (1) to pass the reverse gear.