Motor Vehicle Tank Flap Linkage With Over-Center Locking
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Solution Overview
Problem
Existing tank flap systems for motor vehicles lack secure positioning mechanisms, particularly in the event of power failures, and are not suitable for both electric and combustion engine-driven vehicles.
Innovation Solution
A coupling lever connects a crank rocker to a four-joint mechanism, allowing the tank flap to be locked in a closed position via an over-center position, and an emergency unlocking lever ensures manual override in case of power failure, with a drive lever and braking member stabilizing the flap's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a purely electric motor drive is used to move the tank flap, then the system is suitable for electric motor vehicles, but the system lacks secure positioning in the event of power failures
Solution Approach 1:
The drive system is segmented into an electric motor drive for normal operation and a separate manual emergency unlocking mechanism for backup. This segmentation allows the system to maintain reliability during power failures by providing an independent manual override path that does not depend on electrical power.
Solution Approach 2:
The emergency unlocking lever is pre-positioned and mechanically ready to release the over-center locking mechanism if needed. The manual unlocking path is prepared in advance, allowing immediate action during power failures without requiring additional activation steps or power sources.
2Ease of operation
If the tank flap is made movable between closed and open positions using a four-joint mechanism, then access to the tank recess is enabled, but secure positioning and locking in the closed position is difficult to achieve
Solution Approach 1:
The over-center positioning mechanism utilizes curved geometric paths in the four-joint mechanism to create a mechanical lock. As the mechanism moves through its range of motion, it passes through a critical over-center position where the geometry naturally locks the tank flap in the closed position, providing secure positioning without additional locking components.
3Reliability
If the crank rocker and coupling lever are designed to be movable into an over-center position, then the tank flap can be mechanically locked, but the system becomes more complex
Solution Approach 1:
The locking function is merged with the normal movement mechanism itself. The over-center position is achieved through the inherent geometry of the four-joint mechanism and coupling lever, rather than adding a separate locking device. This integration maintains reliability while minimizing additional complexity.
4Reliability
If an emergency unlocking lever is added for manual override, then reliability during power failures is improved, but device complexity increases
Solution Approach 1:
The emergency unlocking lever is designed to be manually operated directly by the user without requiring tools or additional systems. The mechanical advantage and leverage are built into the lever design itself, allowing it to self-effect the unlocking action through simple manual force applied by the operator.
Data Source
AI summary
A tank flap system including a base fixed to the vehicle, and a tank flap mounted on the base by a four-joint mechanism so as to be movable between a closed position closing a tank recess and an open position exposing the tank recess. The system further includes a drive motor coupled to the four-joint mechanism to move the tank flap between the closed position and the open position and a coupling lever connecting a crank rocker, co-rotating with a drive shaft of the drive motor, to the four-joint mechanism in a movement-transmitting manner to move the four-joint mechanism between the closed position and the open position of the tank flap when the drive motor is activated, and the crank rocker and the coupling lever are in the closed position of the four-joint mechanism, movable into an over-center position blocking an opening movement of the four-joint mechanism.