Fluid Control Valve with Thin DLC Coating for Low-Temperature Sealing
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Solution Overview
Problem
Existing fluid control valves and electromagnetic combination valves face challenges in maintaining airtight performance and non-adhesive properties under low-temperature conditions, particularly in evaporative emission control systems, due to issues with adhesive substances and wear of DLC coatings.
Innovation Solution
A fluid control valve design featuring a thin diamond-like carbon (DLC) coating with Vickers hardness between Hv 50 and Hv 500 on the valve seal and rubber seal portions, combined with a metallic valve seat and a non-adhesive agent on the valve seat surface, to ensure airtight performance and prevent adhesion while enhancing anti-abrasion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a fluorocarbon resin coating is formed on the sealing rubber surface to prevent adhesion, then the non-adhesive performance is improved, but the airtight performance deteriorates under low-temperature condition due to surface hardening
Solution Approach 1:
The invention changes the key parameter of the DLC coating hardness from conventional high hardness (Hv1000 or more) to a specific range (Hv200 to Hv800). This parameter modification allows the coating to maintain non-adhesive properties while preventing surface hardening that would compromise airtight sealing under low-temperature conditions.
Solution Approach 2:
The invention uses diamond-like carbon (DLC) coating, which is a composite material combining properties of diamond and graphite. This composite structure provides both the non-adhesive characteristics needed to prevent rubber-stick and the appropriate surface properties to maintain airtight sealing, resolving the contradiction between adhesion prevention and sealing performance.
2Object-generated harmful factors
If a thick DLC coating is formed to prevent adhesion and provide durability, then the non-adhesive performance and anti-abrasion performance are improved, but the airtight performance deteriorates due to surface irregularities
Solution Approach 1:
The invention optimizes the coating thickness parameter to a specific range (1 μm to 10 μm). This controlled thickness ensures sufficient non-adhesive performance and durability while maintaining surface smoothness for proper sealing, avoiding the surface irregularities that would occur with thicker coatings.
Solution Approach 2:
The invention applies the DLC coating specifically to the sealing surface of the valve where adhesion prevention is most critical, while controlling the local thickness and properties to maintain sealing quality. The coating is applied only where needed rather than uniformly throughout the entire valve structure.
3Object-generated harmful factors
If a molybdenum disulfide coating is formed to decrease friction and prevent adhesion, then the non-adhesive performance is improved, but the airtight performance deteriorates due to surface asperities from powder grains
Solution Approach 1:
The invention replaces molybdenum disulfide powder coating with a diamond-like carbon (DLC) coating, which forms a continuous, smooth film rather than a granular structure. This material substitution eliminates surface asperities while maintaining non-adhesive properties, resolving the contradiction between adhesion prevention and airtight sealing.
Solution Approach 2:
The invention substitutes the powder-based molybdenum disulfide coating system with a film-based DLC coating system. This substitution transitions from a particulate material that creates surface irregularities to a continuous film material that provides both non-adhesive performance and surface smoothness for proper sealing.
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 solution effectively maintains airtight performance and non-adhesive properties under low-temperature conditions, improving durability and reliability by reducing abrasion and adhesion issues, thus ensuring consistent valve operation in evaporative emission control systems.
Implementation Method 1
a surface treatment method to form a fluorocarbon resin coating, a molybdenum disulfide coating or a diamond-like carbon (hereinafter referred to as DLC) coating on the surface of the rubber formed part
Data Source
AI summary
A fluid control valve has: a housing in which a fluid passage is formed; a valve seat in which a fluid flow hole is formed to be communicated with the fluid passage; and a valve that is formed from rubber elastic body. At least a part of the housing is formed from resin. The valve has a valve seal portion and is installed in the housing to be able to close the fluid flow hole. In a valve-closing time, the valve seal portion is seated on the valve seat. The valve seal portion is coated by a thin diamond-like carbon coating having hardness between Hv 50 and Hv 500 in Vickers hardness.