Bonnet Safety Hook Return Surface Geometry
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Solution Overview
Problem
The existing motor vehicle bonnet safety hooks often fail to maintain their locking function due to increased resisting torque at the pivot connection, leading to the hook remaining in the open position without user realization, potentially causing damage and loss of control during vehicle movement.
Innovation Solution
A safety hook design featuring a return surface that engages with the striker plate after the hooking surface has passed, ensuring automatic return to the locking position, even in the absence of a spring or proper operation, by forming a C-section cavity with the hooking surface and having an inclined surface to slide over the striker, enhancing reliability without additional user manipulation or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple riveted steel axis is used for the pivot connection, then the device complexity is reduced and manufacturing cost is lowered, but the reliability deteriorates as the resisting torque increases over time causing the hook to remain in the open position
Solution Approach 1:
The patent introduces a return surface with a specific curvature profile on the hook that interacts with the striker plate. This curved surface ensures that during bonnet closing, the hook is automatically guided back to the correct engagement position relative to the striker, compensating for pivot connection wear and torque increase without requiring complex mechanisms
2Reliability
If the hook is designed to automatically return to the locking position, then the reliability is improved, but the device complexity increases due to additional components like springs
Solution Approach 1:
The hook utilizes the existing closing movement of the bonnet and the geometry of the return surface to automatically return to the engagement position. The system serves itself by using the operational motion (bonnet closing) to reset the safety hook, eliminating the need for separate return springs or actuating mechanisms
Solution Approach 2:
The return surface is pre-configured with a specific profile that anticipates the pivot connection deterioration. The geometry is designed so that during normal closing operation, the hook is proactively guided back to the correct position before wear could cause failure, preventing the problem rather than reacting to it
3Productivity
If the hooking surface engages with the striker early in the closing movement, then the engagement is established sooner, but the reliability decreases because the hook may not be properly positioned if the pivot connection has high resisting torque
Solution Approach 1:
The return surface is designed with a specific curvature profile that delays the engagement of the hooking surface with the striker until the hook has been properly positioned by the geometric guidance. This ensures that even with high pivot torque, the hook engages at the correct position and orientation, maintaining reliability while still achieving timely engagement
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 safety hook ensures reliable engagement and prevents accidental opening of the bonnet, maintaining vehicle control and safety without additional costs or user effort, as it automatically returns to the locking position during the closing movement.
Implementation Method 1
a return surface arranged opposite the hooking surface, arranged to come into contact with the striker during the engagement movement and to cause the hook to pivot into an engagement position
Implementation Method 2
an inclined surface capable of cooperating by sliding with a surface of a fixed element of the vehicle and of causing it to tilt in order to engage with a keeper
Data Source
Figure 1~2
AI summary
The invention relates to a motor vehicle bonnet hood (2) safety catch (4), the catch (4) collaborating with a strike (6) situated on the margins of the engine compartment. The catch (4) comprises a return surface (12) intended to come into contact with a corresponding surface (14) of the strike (6) when the bonnet hood (2) is closed, and when the catch engages with the strike (6), so as to cause the catch (4) to pivot in the direction of engagement. This movement constitutes an additional safety feature ensuring a return movement of the catch when the catch pivots during the closure operation, without which this return movement could be endangered should the return spring fail and/or if the resistive torque at the catch pivot point is too high.