Seat Reclining Device Spiral Spring Guide Recess
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Solution Overview
Problem
The existing seat reclining device experiences reduced spiral spring force due to increased frictional resistance caused by the outer periphery of the spiral spring contacting the inner periphery of the lower arm, leading to decreased effectiveness in adjusting the reclining angle of the seat back.
Innovation Solution
The seat reclining device incorporates a guide recessed portion at the lower arm that accommodates a straight line portion of the spiral spring, preventing contact between the outer and inner peripheries and ensuring the spiral spring remains fixed on the rotational axis line of the cam, thereby maintaining the biasing force and preventing frictional losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guide hole is provided in the lower arm to guide the spiral spring, then the spiral spring can be guided along the rotational axis line, but the spiral spring still contacts the inner peripheral surface of the lower arm causing blackening
Solution Approach 1:
The spiral spring is divided into a wound portion and a straight line portion. The straight line portion is separated from the curved wound portion and extends along the guide recessed portion, preventing contact with the lower arm's inner peripheral surface while the wound portion remains engaged with the cam.
Solution Approach 2:
A guide recessed portion is introduced as an intermediary structure within the lower arm's guide hole. This recessed portion accommodates the straight line portion of the spiral spring, acting as a mediator that guides the spring along the rotational axis line and prevents direct contact between the spring and the lower arm's inner peripheral surface.
2Object-affected harmful factors
If the spiral spring is guided to prevent contact, then blackening is prevented, but the structure becomes more complex
Solution Approach 1:
The guide recessed portion is nested within the lower arm's guide hole structure. The straight line portion of the spiral spring is nested within the guide recessed portion, creating a compact hierarchical structure that prevents blackening without adding external components.
3Ease of operation
If the spiral spring contacts the inner peripheral surface during reclining, then the spring can move freely, but blackening occurs on the lower arm
Solution Approach 1:
The guide recessed portion is designed with specific local geometry that allows the straight line portion of the spiral spring to move freely along the rotational axis line while preventing contact with the lower arm's inner peripheral surface. The recessed portion's shape is optimized to provide guidance without restriction.
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 effectively transmits the spiral spring's biasing force to the cam, ensuring the seat back can be adjusted smoothly without frictional resistance, maintaining the spring force and preventing contact between the spiral spring and the lower arm's inner periphery.
Implementation Method 1
a spiral spring (34) which has an inner end portion (34b) engaged with the cam (32), an outer end portion (34a) engaged with the lower arm (11) and a wound portion (34c) formed by winding and provided between the inner end portion and the outer end portion
Implementation Method 2
an accommodating portion (11a) includes a guide recessed portion (11b2) accommodating the straight line portion therein and being in contact with the inner peripheral side surface of the straight line portion
Data Source
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AI summary
It is an object of the invention to provide a seat reclining device which can prevent the contact between the outer peripheral portion of the spiral spring and the inner peripheral surface of the lower arm by holding the spiral spring on to the rotational axis line of the cam without adding structural components. For the above purpose, the spiral spring 34 is provided which has an inner end portion 34b engaged with the cam 32, an outer end portion 34a engaged with the lower arm 11 and a wound portion 34c formed by winding and provided between the inner end portion and the outer end portion wherein the outer end portion of the spiral spring includes a straight line portion 34a1 extending consecutively from the wound portion and an accommodating portion 11a includes a guide recessed portion 11b2 accommodating the straight line portion therein and being in contact with the inner peripheral side surface of the straight line portion and being in contact with the outer peripheral side surface of the straight line portion at a further outer end than the contact point with the inner peripheral side surface.