End Coil Spring Geometry for Lateral Force and Rigidity
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Solution Overview
Problem
Conventional coil springs used in internal combustion engines and high-pressure pumps experience rigidity deterioration when elongating bearing surfaces around the axial line, leading to increased lateral forces and operational issues.
Innovation Solution
A coil spring design with a first and second end coil part having bearing surfaces that extend circumferentially, where the displacement length from the outer end to the inner end is set to the spring wire thickness, and the displacement length by a half turn is less than half the thickness, maintaining rigidity while preventing lateral forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If bearing surfaces are elongated around the axial line to prevent lateral force, then lateral force is reduced, but rigidity of the end coil part deteriorates
Solution Approach 1:
The patent applies local quality by creating different structural characteristics in different regions of the end coil part. Specifically, the outer end portion is designed with increased thickness (making it locally stronger and more rigid) while the bearing surface is elongated circumferentially (extending from outer end toward inner end). This allows the bearing surface to be extended for lateral force prevention without compromising the rigidity of the outer end portion, as the thickened outer end portion maintains structural strength despite the bearing surface extension.
2Stability of the object's composition
If bearing surface is extended over half a turn to stabilize attitude, then attitude stability is improved, but thickness of outer end portion is reduced
Solution Approach 1:
The patent applies inversion by reversing the conventional approach to bearing surface design. Instead of having the bearing surface extend from the inner end toward the outer end (conventional design), the patent extends the bearing surface from the outer end toward the inner end of the end coil part. This inverted approach allows the bearing surface to be extended over half a turn for attitude stability while the outer end portion maintains its thickness, because the bearing surface starts at the outer end and moves inward rather than outward.
3Strength
If displacement length by half turn is reduced to maintain thickness, then rigidity is maintained, but bearing surface area is limited
Solution Approach 1:
The patent applies dimensionality change by utilizing the circumferential dimension (around the axial line) to extend the bearing surface area, rather than increasing the axial displacement length. The bearing surface is extended circumferentially from the outer end toward the inner end of the end coil part, allowing the bearing surface area to be increased without increasing the axial displacement length by half a turn. This maintains the thickness of the outer end portion and preserves rigidity while still providing adequate bearing surface area through circumferential extension.
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 design effectively secures the thickness of the outer end portions, preventing rigidity reduction and lateral force occurrence even when bearing surfaces extend over half a turn, thus stabilizing the coil spring's attitude during compression.
Implementation Method 1
This coil spring is a component intended to axially exert elastic force when axially compressed
Implementation Method 2
it is known to also produce, in addition to the elastic force in the axial direction, force (lateral force) in the direction perpendicular to the axial direction when compressed
Data Source
AI summary
A coil spring of this invention includes a first end coil part with a first bearing surface facing to the first side in the axial direction, a second end coil part with a second bearing surface facing to the second side in the axial direction and a central coil part connecting the first and second end coil parts. A displacement length in the axial direction from the outer end portion until the inner end portion of the first end coil part is a thickness of a spring wire forming the coil spring so that a space between the outer end portion of the first end coil part and an inner end portion of the central coil part is zero, and a displacement length in the axial direction between the outer end portion of the first end coil part and a point away along the circumferential direction from the outer end portion toward the inner end portion of the first end coil part by a half of turn around the axial line is less than a half of the thickness of the spring wire.