Conical Sealing Ring for Spark Plug Gastight Seal
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Solution Overview
Problem
Existing spark plug designs face challenges in achieving a reliable gastight seal, particularly with cylinder heads made of light metal alloys that have porous surfaces, and in preventing deformation of sealing rings during installation, which can compromise the seal's effectiveness.
Innovation Solution
A spark plug device with a conical sleeve sealing surface and a reshaped sealing ring that is secured in a captive fashion using a retaining groove, allowing for axial reshaping without radial deformation, ensuring a uniform seal over the circumference and reducing the risk of damage to the sleeve surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing ring is compressed between a shoulder of a metal sleeve and a cylinder head sealing surface, then a gastight seal is produced, but the sealing ring may be crushed or deformed during installation, compromising seal effectiveness
Solution Approach 1:
The sealing ring is pre-formed with a conical shape matching the sleeve sealing surface before installation. This preliminary shaping ensures that during compression, the sealing ring conforms to the intended geometry without crushing or deformation, maintaining its structural integrity and sealing effectiveness
Solution Approach 2:
The sealing ring is designed with a conical surface that matches the conical sealing surface on the metal sleeve. This curved geometric design allows the sealing ring to distribute compression forces evenly across its surface, preventing localized crushing and deformation while maintaining a reliable gastight seal
2Stress or pressure
If a sealing ring is compressed to produce a gastight seal, then sealing pressure is increased, but higher tightening torque is required, which is particularly problematic for smaller thread sizes
Solution Approach 1:
The conical sealing surface geometry allows the sealing ring to be compressed axially while the conical shape converts this axial force into radial sealing pressure. This mechanical advantage enables high sealing pressure to be achieved with lower tightening torque, as the conical surface distributes and amplifies the compressive force effectively
Solution Approach 2:
The invention changes the geometric parameters of the sealing ring by pre-forming it with a conical shape that matches the sleeve sealing surface. This parameter change in geometry allows the sealing ring to generate high sealing pressure through axial compression alone, without requiring excessive tightening torque
3Reliability
If a sealing ring is reshaped radially to reduce inner diameter, then the sealing ring is secured in captive fashion, but radial deformation may damage the sealing surface
Solution Approach 1:
The sealing ring is pre-formed with the final conical shape and correct inner diameter before installation. This preliminary action eliminates the need for radial deformation during installation, as the sealing ring already has the proper geometry to engage with the retaining groove and secure itself in captive fashion without damaging the sealing surface
4Weight of stationary object
If cylinder heads are made from light metal alloys using lost-foam casting to reduce vehicle weight, then production cost is reduced, but the surface becomes more porous, making it difficult to achieve a seal
Solution Approach 1:
The sealing ring is pre-formed with a conical shape that precisely matches the conical sealing surface on the metal sleeve. This preliminary shaping ensures that when compressed, the sealing ring creates a uniform contact pressure distribution that effectively seals against porous cylinder head surfaces, compensating for the porosity issues inherent in lost-foam casting processes
Solution Approach 2:
The conical geometry of the sealing ring and matching sealing surface creates a tapered compression zone that distributes sealing pressure evenly across the interface. This curved geometric design is particularly effective on porous surfaces as it prevents pressure concentration points that would otherwise allow gas leakage through the porous material
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 design achieves increased sealing pressure with lower tightening torque, particularly beneficial for smaller thread sizes, and provides a uniform seal even on porous cylinder head surfaces, reducing logistics costs and ensuring effective gas containment.
Implementation Method 1
the sealing ring blank is reshaped into a sealing ring that has an inner section whose diameter is smaller than the fastening section outer diameter
Data Source
AI summary
A spark plug device that includes a spark plug and a sealing ring, and a method for producing the same. The spark plug may include a body, an insulator, a center electrode, and a ground electrode. The sealing ring is secured to the body in a captive fashion. A fastening section of the body has an outer diameter that is greater than an inner diameter of the sealing ring, which has been reshaped from a flat sealing ring blank into a conical sealing ring.