Water Pump Lip Seal Composition for Fluid Resistance
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Solution Overview
Problem
Lip seals for water pumps made of rubber-like materials face issues with softening and swelling when exposed to aqueous fluids like LLC, leading to reduced sealing properties and torque, and the formation of deposits due to low lubricity and osmosis, which affects rotation and heat generation.
Innovation Solution
A vulcanization-molded rubber composition comprising hydrogenated nitrile rubber, EPDM, or fluororubber, with specific fillers, coupling agents, and co-crosslinking agents, which includes carbon black or silica as reinforcing fillers and aluminum silicate or calcium silicate with a particle diameter of 1 µm or more, to prevent softening, swelling, and deposit formation, while enhancing lubrication and reducing torque and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rubber-like elastic material is used for the lip seal, then sealing properties are provided, but softening and swelling occur when exposed to aqueous fluids like LLC
Solution Approach 1:
The patent uses a composite rubber composition comprising hydrogenated nitrile rubber (30-70 parts), EPDM (10-40 parts), fluororubber (10-40 parts), and inorganic fillers (20-80 parts). This composite structure combines the advantages of different rubber materials to achieve resistance to aqueous fluids while maintaining sealing properties. The specific combination and ratios of rubber types create a material that resists softening and swelling in LLC environments.
Solution Approach 2:
The patent modifies the chemical composition parameters of the rubber material by specifying precise weight ratios of different rubber types and additives. The composition includes 30-70 parts hydrogenated nitrile rubber, 10-40 parts EPDM, 10-40 parts fluororubber, and specific amounts of fillers and curing agents. These parameter changes transform the base rubber into a fluid-resistant material that maintains dimensional stability while providing effective sealing.
2Reliability
If sliding contact is used between the lip seal and rotating shaft, then sealing function is achieved, but significant abrasion and heat generation occur due to low lubricity
Solution Approach 1:
The patent introduces inorganic fillers (aluminum oxide, silicon carbide, tungsten carbide, zirconium dioxide, iron oxide, titanium oxide, quartz powder, titanium nitride, titanium carbide, or zirconium carbide with Mohs hardness of 6 or more and average particle diameter of 2 μm or less) as intermediary substances. These fillers act as solid lubricants and wear particles that reduce direct rubber-to-shaft contact, thereby reducing abrasion and heat generation while maintaining the sealing function of the sliding contact.
Solution Approach 2:
The patent changes the surface properties of the lip seal by incorporating specific inorganic fillers with controlled particle sizes and hardness values. The fillers have average particle diameters of 2 μm or less and Mohs hardness of 6 or more, which modifies the friction and wear characteristics of the sliding surface. This parameter change reduces the coefficient of friction and prevents excessive heat generation during operation.
3Temperature
If organic phosphoric acid-based LLC is used for cooling, then cooling function is provided, but phosphoric acid compounds accumulate in the shaft and form gaps reducing sealing properties
Solution Approach 1:
The patent uses hard inorganic filler particles (with Mohs hardness of 6 or more) that act as self-cleaning elements. These fillers continuously scrape and remove accumulated phosphoric acid compounds from the shaft surface during rotation. The fillers are sacrificial elements that maintain their abrasive function throughout the seal's service life, preventing gap formation and maintaining sealing properties despite the presence of phosphoric acid-based LLC.
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 prevents softening and swelling, reduces torque and heat generation, and prevents deposit formation, thereby improving the sealing properties and extending the lifespan of the lip seal.
Implementation Method 1
a lip seal for water pump obtained by vulcanization-molding of a rubber composition
Implementation Method 2
1 to 15 parts by weight of a co-crosslinking agent, and 0.5 to 10 parts by weight of an organic peroxide
Implementation Method 3
the low lubricity of sliding surfaces causes significant abrasion due to sliding and leads to high heat generation. Organic acid-based LLC, particularly 2-ethylhexanoic acid-based LLC, causes significant softening and swelling of the lip seal
Implementation Method 4
the low lubricity of sliding surfaces causes significant abrasion due to sliding and leads to high heat generation
Implementation Method 5
In order to improve lubricity in such a case, Patent Document 1 discloses a water pump sealing device using a lubricating grease for a lip lubricating
Data Source
AI summary
Disclosed is a lip seal for water pump made of a rubber-like elastic material, fixed to a housing as a fixed side and in sliding contact with a shaft rotating relative to the housing; the lip seal being obtained by vulcanization-molding of a rubber composition comprising 100 parts by weight of the rubber-like elastic material, 1 to 150 parts by weight of a reinforcing filler, 5 to 90 parts by weight of a non-reinforcing filler having an average particle diameter of 1 µm or more, 0.1 to 5 parts by weight of a coupling agent, 1 to 15 parts by weight of a co-crosslinking agent, and 0.5 to 10 parts by weight of an organic peroxide. The lip seal for water pump provides a materially solution, rather than a structural solution, to prevent softening and volume swelling of the rubber-like elastic material and the generation of deposits in the rotating shaft, which are problematic for rotation torque and LLC resistance.