Shift Drum Blocking Gate Labyrinth Contour
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Solution Overview
Problem
In motor vehicles, particularly electric and hybrid vehicles, the existing shift drum arrangements do not adequately prevent unintentional engagement of the parking brake, which can lead to unsafe driving conditions due to potential actuator malfunctions.
Innovation Solution
A shift drum arrangement with a blocking device featuring a labyrinth contour and a spring-loaded blocking pin that engages in a blocking gate, preventing rotation in one direction and allowing release in the reverse direction, thus requiring a double change in direction for brake engagement, making unintentional activation extremely unlikely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common shift drum arrangement is used to actuate both the dog clutch and friction clutch, then the device complexity is reduced, but the risk of unintentional parking brake engagement increases due to potential actuator malfunctions
Solution Approach 1:
A blocking lever with a blocking pin is introduced as an intermediary mechanical element between the shift drum and the parking brake function. The blocking pin engages in a blocking gate with labyrinth contour to prevent unintentional rotation of the shift drum into the parking brake setting, while allowing intentional double-directional rotation to engage the brake when required.
Solution Approach 2:
The blocking device is designed to preemptively prevent unwanted parking brake engagement by mechanically blocking the shift drum's rotation path. The labyrinth contour in the blocking gate creates a stop contour that the blocking pin strikes against, preventing single-directional activation that could occur due to actuator defects before the brake is engaged.
2Reliability
If a blocking device with labyrinth contour is added to prevent unintentional parking brake engagement, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The blocking function is merged with the existing shift drum arrangement by integrating the blocking lever and blocking pin into the same mechanical system. The blocking gate is formed as part of the shift drum structure, and the blocking lever is positioned to interact with the same rotational path, combining safety functionality with the existing shift mechanism.
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
This solution effectively prevents unintentional engagement of the parking brake, enhancing safety by ensuring that the brake can only be engaged intentionally, even in the event of actuator defects, thereby maintaining vehicle control.
Implementation Method 1
the blocking pin is of spring-loaded design or is of spring-elastic design
Data Source
AI summary
A shift drum arrangement includes a shift drum with at least one first shift gate and/or a shift drum path for actuating at least one shift element of a transmission, in particular of a motor vehicle. A blocking device has a blocking gate and a blocking pin which engages in the blocking gate. The blocking gate has a labyrinth contour, and therefore the blocking pin strikes against a stop contour in one direction of rotation of the shift drum and blocks the further rotation of the shift drum. The block is released after the shift drum is partially rotated back in the reverse direction of rotation.