Reusable Push-Pin Grommet Fastener With Low Insertion Force
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Solution Overview
Problem
Existing pin and grommet fasteners in the automotive industry require high insertion forces and are not easily reusable, leading to increased service and repair costs due to potential damage during removal.
Innovation Solution
A pin and grommet fastener design featuring a grommet with longitudinally extending leg members and a knuckle connected at a hinge, along with a pin having locking members and a driving protrusion that automatically engages the joining aperture to lock the fastener in place during insertion, reducing insertion force and allowing for reusability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional pin and grommet fasteners are used, then the fastener can be inserted into the joining part, but high insertion forces are required and the fastener cannot be easily reused
Solution Approach 1:
The fastener is divided into two separate components: a pin and a grommet. The pin contains locking members that engage with corresponding features in the grommet and the joining part, allowing the pin to be inserted first followed by the grommet. This segmentation enables the locking mechanism to engage progressively, reducing the peak insertion force required while maintaining secure attachment and reusability.
Solution Approach 2:
The pin is prepared in advance with locking members positioned to engage with the grommet and joining part. When the pin is inserted into the joining part, the locking members are already positioned to automatically engage with corresponding features in the grommet as it is installed, eliminating the need for separate locking actions and reducing insertion force requirements.
2Ease of repair
If traditional pin and grommet fasteners are used, then the fastener can join components, but the fastener may be permanently damaged during removal requiring replacement
Solution Approach 1:
The locking mechanism is designed with dynamic characteristics that allow it to engage securely during installation but disengage cleanly during removal. The locking members on the pin engage with corresponding features in the grommet and joining part through a controlled sequence, and during removal, the forces are distributed to prevent permanent deformation, allowing the fastener to be reused without damage.
3Ease of operation
If steps are taken to reduce the required insertion force of a pin and grommet fastener, then insertion becomes easier, but the retention capability of the fastener is reduced
Solution Approach 1:
The fastener system is segmented into a pin with locking members and a grommet with corresponding engagement features. The pin is inserted first, creating initial mechanical interference with the joining part, followed by the grommet which engages with both the pin and the joining part. This segmented approach distributes the locking action across multiple interfaces, reducing peak insertion forces while maintaining strong retention capability through cumulative engagement.
Solution Approach 2:
The pin and grommet are designed to work together as an integrated system where the locking members on the pin combine with corresponding features in the grommet to create a unified locking mechanism. This merging of functions allows the fastener to achieve both low insertion force and high retention capability through the cooperative interaction of its components.
Data Source
AI summary
A pin and grommet fastener includes a grommet that defines a central aperture and includes at least two adjacent longitudinally extending leg members that each include a frame, a knuckle and a tether. The knuckle is connected to the frame at a hinge region that is designed to permit the knuckle to move relative to the frame. The tether connects the knuckle to a base surface of grommet in order to limit movement of the knuckle relative to the frame. The fastener includes a pin that has a first locking member to retain the pin in a first position relative to the grommet in which the longitudinally extending leg members are in a laterally unexpanded state. The pin also has a second locking member to retain the pin in a second position relative to the grommet in which the longitudinally extending leg members are in a laterally expanded state.