Mechanical seal for rotating shaft

Details Mechanical seal for rotating shaft Mechanical seal for rotating shaft

2001-02-08

2004-02-03

Knight, Anthony (Department: 3676)

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

C277S352000, C277S375000

Reexamination Certificate

active

06685191

ABSTRACT:

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
In the use of pumps or other rotating shaft machinery in which liquids or emulsions are present, it is necessary to prevent leakage of the liquids or emulsions from the machine. In early applications, rope or cordage was stuffed around the drive shaft to create a seal. Later, mechanical seals were developed which include a member locked to the rotating shaft and rotatable within a stationary mounting flange mounted to the body of the machine. The seal is achieved by attaching a bearing face to the shaft and another bearing face to the housing of the equipment with each face mechanically loaded against the other to form a seal between the rotating member and the mounting flange. A fluid is used to lubricate and cool the faces to avoid destruction due to friction between the two parts.
Conventional seals are longitudinally compressed and longitudinally fixed within the mounting flange which is mounted to the pump body. A collar having multiple radially disposed screws is typically used to attach the rotating parts of the seal to the driven shaft. When the bearing surfaces of such mechanical seals become worn, it is necessary to remove the entire seal and mounting flange assembly and either discard the assembly or return the entire assembly to a repair facility for refurbishing. That is, prior art seals are not typically amenable to disassembly in the field of the bearing components from the mounting end plate. Because of this, users of such mechanical seals must inventory bulky and expensive spare parts which include mounting flanges.
Conventional mechanical seals are also provided with spacers to maintain axial alignment of the rotating element within the mounting flange, such spacers requiring removal during installation. Frequently, seal members are located in inaccessible and tight spaces, making them difficult to remove and replace while maintaining proper axial alignment and while accessing radial set screws to retain the rotatable element of the seal to the rotatable shaft. Additionally, existing seal assemblies are provided with lubrication passageways which are dead ended at the component to be lubricated, leading to heat damage to the lubricants. There is a need for an improved mechanical seal which may be easily disassembled at the installed location and quickly repaired. A need also exists for a mechanical seal which may be more easily installed on the pump or other rotating machinery and which allows better lubrication and cooling of bearing components.
SUMMARY OF THE INVENTION
This disclosure concerns a cartridge mechanical seal which may be used with pumps or any rotating shaft equipment requiring a liquid to be sealed in the equipment where a drive shaft enters the equipment housing from the outside through a shaft opening that would allow the liquid to leak or drain from the housing. Though pumps are a primary use for such seals, the seals may also be used in a compressor, mixer, fan, reactor, agitator, conveyor or any other rotating shaft equipment.
The improved mechanical seal includes an end plate which receives a seal cartridge, the cartridge including a closely fitting cylindrical stator assembly having an axial opening through it. The stator assembly is received in a central opening in the end plate which is mounted to the housing of the pump or other rotating shaft machinery to be sealed. A rotor assembly is axially received within the cylindrical opening of the stator assembly. Opposing annular faces on the rotor assembly and the stator assembly provide bearing surfaces between the stator assembly and the rotor assembly, those bearing faces being internal to the cartridge. A clamp having a radial gap may be fixed to the rotor assembly after the cartridge has been installed in the end plate and the rotor assembly has been received on the pump drive shaft. The clamp is retained to the rotor assembly by a radial pin and the clamp is clinched around the drive shaft of the pump by a tightening screw which reduces the gap of the clamp. An annular groove in an end face of the stator assembly receives multiple locator pins which are retained in the opposing end face of the clamp. The locator pins space the clamp away from the stator assembly. The end plate and stator assembly have intake and exit openings in registry such that lubricants may flow past the bearing surfaces of the stator assembly and the rotor assembly. Because the clamp has a smaller diameter than the axial opening of the end plate, the end plate may be removed without first removing the clamp and cartridge from the drive shaft thereby facilitating removal of the seal doing during repair.
It is an object of the invention to provide a field repairable mechanical seal for a pump or other rotating shaft machinery.
It is also an object of the invention to provide a mechanical seal which allows disassembly of disposable bearing elements from the mounting flange of the seal.
It is a further object of the invention to provide a mechanical seal which reduces the cost of and space required for inventory of spare seals and eliminates the need to keep mounting flanges as part of seal inventory.
It is yet another object of the invention to provide an improved seal cartridge which may be used on multiple shapes of end plate.
It is also an object of the invention to provide an improved mechanical seal which allows use of a single screw to clamp the seal rotating parts to the pump drive shaft.
It is further an object of the invention to provide a mechanical seal with improved concentricity of the moving and stationary components of the seal.
It is still another object of the invention to provide a seal which allows greater ease and speed of installation along with easier shaft adjustment.
It is a further object to provide a mechanical pump seal which allows removal of the mounting flange without releasing the seal cartridge from the drive shaft.
These and other objects of the invention will become apparent from examination of the description and claims which follow.


REFERENCES:
patent: 4457517 (1984-07-01), Dunegan
patent: 5344164 (1994-09-01), Carmody et al.
patent: 5489105 (1996-02-01), Attenasio et al.
patent: 6003875 (1999-12-01), Ellis et al.
patent: 6231052 (2001-05-01), Forlander
patent: 6357753 (2002-03-01), Yamasaki et al.

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