Mechanical Seal Narrow Face Width Lubricant Film
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Solution Overview
Problem
Conventional mechanical seals experience high heat generation and surface abrasion due to low self-lubricity, leading to thermal stress cracks and deteriorated sealing performance, especially when sealing fluids near their boiling point, and narrowing the sliding surface width exacerbates abrasion and damage.
Innovation Solution
A mechanical seal design with a narrow face width seal surface that deforms to form a fluid lubricant film, featuring a rectangular nose portion, balanced seal rings, and a tapered inner surface to efficiently circulate fluid and reduce heat generation, while maintaining contact pressure and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the width of the sliding surface is narrowed to reduce heat generation, then heat generation decreases, but abrasion amount increases and sealing performance deteriorates
Solution Approach 1:
The patent changes the physical parameters of the seal surface by controlling the crystal grain size (10-100 μm) and hardness (40-60 HRC) of the sintered compact, creating a surface that generates appropriate undulation to form lubricant films while maintaining narrow width for reduced heat generation
Solution Approach 2:
The patent introduces a lubricant film as an intermediary between the sliding surfaces, formed by undulation generated from the specific crystal structure and hardness of the sintered compact, preventing direct solid contact and reducing both heat generation and abrasion
2Temperature
If the width of the sliding surface is narrowed to reduce heat generation, then heat generation decreases, but the sliding surfaces suffer severe abrasion and damage
Solution Approach 1:
The patent uses composite sintered compact material containing iron powder, graphite powder, and binder resin, where graphite provides self-lubrication properties and the specific composition creates a surface that resists abrasion while maintaining narrow width
Solution Approach 2:
The patent optimizes the hardness parameter to 40-60 HRC and crystal grain size to 10-100 μm, creating a surface structure that is sufficiently hard to resist abrasion damage while maintaining the narrow width needed for reduced heat generation
3Reliability
If conventional sealing methods are used to inhibit vaporization of sealed fluid, then vaporization is inhibited, but lubricant film vaporization occurs when sealing fluids near boiling point
Solution Approach 1:
The patent introduces a lubricant film formed by undulation as an intermediary protective layer between the sliding surfaces, which remains stable even when sealing fluids near boiling point, preventing direct contact and heat transfer that would cause vaporization
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
Significantly reduces heat generation and abrasion, maintains sealing performance, and prevents damage by forming a fluid lubricant film and efficiently removing heat, even at narrow sliding surface widths.
Implementation Method 1
the seal surface having a narrow face width exhibits low rigidity. Therefore, the seal surface is susceptible to deformation. With this, when the rotary seal ring rotates, the seal surface having a narrow face width flexibly follows the opposing seal surface. As a result of that, appropriate undulation generates on the sliding surface, and thereby it enables to preferably form a fluid lubricant film on the sliding surfaces.
Implementation Method 2
appropriate undulation generates on the sliding surface, and thereby it enables to preferably form a fluid lubricant film on the sliding surfaces
Implementation Method 3
a tapered inner surface to efficiently circulate fluid and reduce heat generation
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A mechanical seal device for sealing a fluid inside of machine at a space formed between a stuffing box and a rotary shaft, comprises a seal cover attached to the stuffing box, a stationary seal ring attached to the seal cover and provided with a first seal surface, a rotary seal ring attached to the rotary shaft and provided with a second seal surface capable of sliding on the first seal surface, and a collar rotating together with the rotary shaft. The seal surface of either one of the stationary seal ring and the rotary seal ring is formed so that a face width of a radial direction is narrower than the other seal surface. A clearance is formed between a back surface opposing to the second seal surface of the rotary seal ring and the collar. The rotary seal ring is elastically held in an axial direction of the rotary shaft to rotate together with the collar.