Compliant Pivot Joint for Vehicle Seat Noise Reduction
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Solution Overview
Problem
Vehicle seat pivot joints experience looseness and noise issues due to radial loading and lateral clearance, leading to perceived defects and unwanted movements, which result in buzz, squeak, and rattle noises under fore-aft and lateral loads.
Innovation Solution
A compliant pivot joint design featuring a cup-shaped protrusion, a fastener with a curved shoulder surface, and a bias member, such as a spring disc stack of conical washers, which minimizes unwanted movements and maintains rotational friction within a target range by applying a bias force to reduce chucking and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lateral clearance is provided within the pivot joint to allow rotation and accommodate tolerance stack up, then rotational movement is enabled and assembly is facilitated, but perceived looseness and chucking occur under fore-aft and lateral loads
Solution Approach 1:
The pivot joint transitions from a static clearance design to a dynamic compliant design where the joint characteristics change based on loading conditions. The cup-shaped protrusion and curved shoulder surface create a compliant interface that adapts to applied loads, maintaining stability during rotation while reducing looseness under fore-aft and lateral forces
Solution Approach 2:
The invention changes the physical parameters of the pivot joint interface by introducing a cup-shaped protrusion with specific curvature radius and a curved shoulder surface. These geometric parameter changes create a compliant interface that provides necessary lateral clearance for rotation while limiting excessive movement under load through the specific curvature relationships
2Ease of manufacture
If lateral clearance is provided within the pivot joint, then assembly and tolerance accommodation are facilitated, but buzz, squeak, and rattle noises occur under road vibration
Solution Approach 1:
The specific curvature parameters of the cup-shaped protrusion and curved shoulder surface are designed to maintain optimal contact under vibrational conditions. The curvature radius relationship ensures that the interface remains stable during road vibrations, preventing the loose contact that generates BSR noises while still allowing for assembly tolerance
Solution Approach 2:
The invention converts the potentially harmful lateral clearance that causes noise into a beneficial compliant interface. The cup-shaped protrusion and curved shoulder surface work together to maintain controlled contact that eliminates noise-generating loose movement while preserving the necessary clearance for assembly and rotation
3Strength
If radial loading is applied to the pivot joint, then rotational coupling is maintained, but deformation and wear occur overtime increasing perceived radial looseness
Solution Approach 1:
The geometric parameters of the cup-shaped protrusion and curved shoulder surface are specifically designed to distribute radial loads more evenly across the contact interface. This parameter optimization reduces stress concentration and wear, maintaining the rotational coupling strength while minimizing deformation that would increase radial looseness over time
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 compliant pivot joint design reduces perceived looseness and noise, maintaining low friction and preventing chucking while accommodating lateral loads, thus enhancing the stability and quiet operation of vehicle seats.
Implementation Method 1
a bias member having a bias opening. The shoulder bolt extends through the bias opening and through the cup opening with the shoulder bolt fixedly coupled to the fastener and the curved shoulder surface frictionally engaged with a lower surface of the cup-shaped protrusion. The bias member is spaced between an upper surface of the cup-shaped protrusion and the bolt head and biases the bolt head away from the cup-shaped protrusion.
Data Source
AI summary
A compliant pivot joint is provided for rotationally coupling a link member to a frame member in a vehicle seat. The compliant pivot joint includes a cup-shaped protrusion having a cup opening formed on the link member, a shoulder bolt having a first shaft portion projecting from a bolt head and terminating at a shoulder, a bias member having a bias opening, and a fastener fixedly coupled to the frame member. The shoulder bolt is fixedly coupled to the fastener and extends through the bias opening and through the cup opening. The bias member is spaced between the cup-shaped protrusion and the bolt head and biases the bolt head away from the cup-shaped protrusion. A curved shoulder surface of the fastener is frictionally engaged with the cup-shaped protrusion and the shoulder of the shoulder bolt is frictionally engaged with an end surface of the fastener.