Vehicle Seat Reclining Apparatus Asymmetric Hinge Pin
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Solution Overview
Problem
The existing vehicle seat reclining apparatus experiences operational lag and degraded feel due to circumferential play between the hinge pin and cam, leading to a noticeable delay between the release operation and the release of engagement between teeth, affecting the smooth adjustment of the seatback's angle of inclination.
Innovation Solution
A vehicle seat reclining apparatus with a hinge pin having a fitting shaft portion with two flat surfaces and a fitting hole with parallel inner side surfaces, where the gap in one radial direction is smaller than in the orthogonal direction, and a tension coil spring urging the release lever to reduce axial line inclination, allowing smoother cam rotation and pole movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gap is formed between the fitting shaft portion and fitting hole to absorb axial line inclination, then the cam rotation and pole movement are smoothened, but circumferential play is generated causing operational lag
Solution Approach 1:
The fitting hole is designed with asymmetric gap distribution: a smaller gap in the radial direction (preventing circumferential play) and a larger gap in the axial direction (absorbing axial line inclination). This asymmetric geometry resolves the contradiction by allowing smooth cam rotation without generating operational lag.
2Loss of time
If the gap between fitting shaft portion and fitting hole is reduced to minimize play, then operational lag is reduced, but the ability to absorb axial line inclination is compromised
Solution Approach 1:
The fitting hole employs asymmetric gap dimensions: a smaller radial gap (0.05-0.15mm) to minimize circumferential play and operational lag, while maintaining a larger axial gap to absorb axial line inclination. This asymmetric design simultaneously achieves both requirements.
3Ease of manufacture
If the fitting hole has uniform gap in all directions, then manufacturing is simplified, but it cannot simultaneously minimize circumferential play and absorb axial inclination
Solution Approach 1:
The fitting hole is designed with non-uniform gap distribution: smaller gaps (0.05-0.15mm) in the radial direction for precision and larger gaps in the axial direction for inclination absorption. This asymmetric design prioritizes operational reliability over manufacturing simplicity.
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 configuration reduces operational lag and enhances the feel of the seatback adjustment by minimizing the play in the circumferential direction, stabilizing the rotation and locking operations, and dispersing the load for improved strength and stability.
Implementation Method 1
a supporting urging member locked to the release lever at one leg portion thereof and locked to the seat cushion side or the seatback side where the first bracket is fixed at the other leg portion, and configured to urge the release lever along the radial direction
Implementation Method 2
a locking urging member configured to urge the cam to rotate to cause the outer teeth and the inner teeth to be engaged each other
Data Source
AI summary
Provided is a vehicle seat reclining apparatus comprising: a first bracket, a second bracket, a pole, a cam, a locking urging member, a hinge pin, a fitting hole, a release lever, and a supporting urging member.