Welded Bellows Mechanical Seal for Compact High-Pressure Sealing
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Solution Overview
Problem
Outside-type mechanical sealing devices face challenges in maintaining high seal tightness at increased rotation speeds and liquid pressures while being compact in both axial and radial directions, as existing solutions either increase size or compromise on seal tightness.
Innovation Solution
A mechanical sealing device utilizing a bellows as an elastic member instead of a spring, with a hollow design that provides uniform pressing force around the circumference, allowing for a smaller size without increasing axial or radial dimensions, and featuring a welded type bellows for enhanced pressing force and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing force of the spring mechanism is increased to enhance seal tightness, then the seal tightness is improved, but the size of the mechanical sealing device in the axial direction increases
Solution Approach 1:
The patent employs a bellows structure (a flexible element) to replace the traditional spring mechanism. The bellows can elastically deform to provide pressing force on the sealing rings, achieving high seal tightness while maintaining a compact axial size. The flexible nature of the bellows allows it to store and release elastic energy, providing continuous pressing force without requiring a long axial length.
Solution Approach 2:
The patent changes the physical parameters of the elastic mechanism by using a bellows with specific expansion and contraction characteristics. By adjusting the number of turns, material properties, and geometric parameters of the bellows, the pressing force can be optimized to achieve high seal tightness while keeping the axial dimension small.
2Force
If the number of springs is increased to enhance the pressing force, then the pressing force is improved, but the size of the mechanical sealing device in the radial direction increases
Solution Approach 1:
The patent merges multiple spring functions into a single bellows structure. Instead of using multiple separate springs that would require radial space for mounting, the bellows provides the equivalent or superior pressing force through its elastic deformation, consolidating the force-generating function into one compact radial element.
Solution Approach 2:
The bellows structure provides a compact radial footprint compared to multiple springs. The flexible shell can be configured to provide the necessary pressing force through its geometric design and material properties, avoiding the need to increase radial dimensions to accommodate multiple spring mounting positions.
3Force
If the size of the spring in the radial direction is increased to increase the pressing force, then the pressing force is improved, but the size of the mechanical sealing device in the radial direction increases
Solution Approach 1:
The patent optimizes the parameters of the bellows (number of turns, wire diameter, mean diameter, material modulus) to achieve high pressing force within a compact radial envelope. By carefully selecting these parameters, the bellows can generate sufficient elastic restoring force without requiring a large radial size.
Solution Approach 2:
The bellows structure efficiently utilizes radial space through its corrugated geometry, which allows for significant elastic deformation in a compact form. This flexible shell structure provides high pressing force while maintaining a small radial footprint, avoiding the need to increase radial dimensions.
4Productivity
If the rotation speed is increased to increase the flow rate, then the flow rate is improved, but the liquid pressure on the sliding faces increases causing seal tightness to decrease
Solution Approach 1:
The bellows structure provides a compliant pressing mechanism that can adapt to varying operating conditions. As rotation speed and liquid pressure increase, the bellows elastically deforms to maintain optimal contact pressure between the sealing rings, ensuring consistent seal tightness across a wide range of flow rates and speeds.
Solution Approach 2:
The bellows introduces dynamic compliance to the sealing system. The elastic element can automatically adjust the pressing force in response to changing operating conditions (rotation speed, liquid pressure), maintaining optimal sealing performance without requiring active control mechanisms.
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 device achieves high seal tightness and prevents liquid leakage even at high rotation speeds and pressures, maintaining compact dimensions and durability, with the bellows ensuring uniform pressure distribution and preventing liquid from reaching the sealing members.
Implementation Method 1
a bellows provided around the protrusion so as to be positioned between the housing and the fixed-side annular portion, for pressing the fixed-side annular portion toward the rotation-side annular portion
Implementation Method 2
featuring a welded type bellows for enhanced pressing force and durability
Data Source
AI summary
A mechanical sealing device according to an embodiment of the present invention includes: a sealing ring (13) attached to a protrusion (11a) protruding from a housing (11); a mating ring (23) attached to an end portion of a rotary shaft (21); a welded bellows provided around the protrusion (11a) and located between the housing (11) and the sealing ring (13). The welded bellows (15) presses the sealing ring (13) in an axial direction to cause the sealing ring (13) to be in contact with the mating ring (23), thereby ensuring high pressure force, and in particular, uniform pressure force along its entire circumference, so as to achieve high liquid tightness, while maintaining the sizes in axial and radial directions small. Furthermore, the welded bellows (15) works as a sealing member of blocking a liquid leaked out through the O-ring (14), thereby achieving assured liquid tightness. Accordingly, an outside-type mechanical sealing device can be provided which has a compact size, and is capable of ensuring high liquid tightness in response to a high rotation speed and a high liquid pressure.