Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Reexamination Certificate
2002-02-27
2004-05-04
Knight, Anthony (Department: 3676)
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
C277S389000, C277S390000
Reexamination Certificate
active
06729622
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention proceeds from a ready-to-mount axial face seal, according to the introductory part of claim
1
, for the shaft of a pump, wherein the shaft may be coupled to a drive motor.
Such axial face seals forming a coherent construction unit and having a so-called shaft protection sleeve and which on the market are obtainable under the description cartridge or magazine seal, are known. They comprise essentially the shaft protection sleeve and two units assembled thereupon, specifically a rotating unit, which amongst other things comprises the rotating axial face seal ring, a compression spring axially loading this with a pregiven value as well as an inner elastic sealing ring, and a stationary unit, which amongst other things comprises the stationary counter ring for the rotating axial face seal ring and and an assembly part for the screw fastening of the axial face seal to the housing end wall of a pump. The longitudinal section of the shaft protection sleeve which projects out of the housing end wall when the axial face seal is mounted comprises at its free end e.g. an integral collar which is thicker in relation to the wall thickness of the shaft protection sleeve, with several radial threaded holes in which there are seated screws for fastening the shaft protection sleeve on the shaft of the pump.
For axial face seals of this known type in the end wall of the pump housing there is provided a special mounting space fixed by the pump manufacturer. The expensive pumps equipped with this seal provide a high power of 25 KW and larger and have a shaft diameter which as a rule is larger than 30 mm. For pumps with a considerably lower power, whose shaft has a diameter of 8 to 30 mm, there is applied an axial face seal design standardised according to DIN standards, which comprises no shaft protection sleeve and for which there is to be applied a mounting space standardised to the desired shaft in each case in the end wall of the pump housing. In the case of a defect of such a standard seal the exchange of this is time-consuming and expensive since the pump in the region of the seal to a considerable extent must be disassembled and again reassembled, which also applies to the individual parts of the standard seal, and for these working procedures there are required specialised personnel. Furthermore the use of a ready-to-mount axial face seal of the cartridge type in a standardised mounting space and thus the exploitation of the advantage of a rapid exchange of such an axial face seal is not possible since an axial face seal of the cartridge type, thus with a shaft protection sleeve, does not fit into the standardised mounting space since this mounting space in diameter is too small for the axial face seal of the cartridge type larger in outer diameter.
SUMMARY OF THE INVENTION
The object of the present invention lies in improving a ready-to-mount axial face seal of the above mentioned type to the extent that it is suitable for application in a standardised mounting space for a standard axial face seal design without a shaft protection sleeve.
The solution of this object is specified in patent claim
1
.
The solution according to the invention permits the exploitation of the advantage of the axial face seal of the cartridge construction type, specifically its quick and inexpensive exchangeability in the case of a defect, also with those standardised mounting spaces which are envisaged for axial face seal designs standardised according to DIN, without shaft protection sleeve. Such mounting spaces and the associated standard axial face seal dependent on the shaft diameter of the pump selected in each case are used for centrifugal pumps with a smaller power of about 0.35 KW to 25.0 KW and with a pump shaft diameter of about 8 to 30 mm. These pumps are manufactured in large series and are therefore inexpensive in manufacture so that an exchange of a defect standard axial face seal with such a pump for reasons of cost is uneconomical and therefore mostly leads to a scrapping of the pump. With the axial face seal according to the invention the corresponding repair costs with cheap pumps of the previously mentioned type are however considerably reduced since a disassembly and a renewed assembly of the end wall of the pump housing including the individual sealing location are no longer required and may be effected by trained personnel. A defect cartridge seal according to the invention may be quickly exchanged since it itself needs only to be released from the pump end wall and the pump shaft after previously the drive motor has been decoupled from the pump, whereupon the defect cartridge seal is pulled off from the pump shaft. The assembly procedures for a new axial face seal according to the invention of the cartridge type is effected in reverse succession. Apart from the renewed use of the pump a further advantage of the axial face seal according to the invention lies in the fact that the user may select such a pump independently of whether he wishes to have mounted therein an axial face seal according to the invention or a known standard axial face seal.
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Mechanical Seals—Principled Dimensions, Designation and Material Codes; English Version EN 12756: 2000.
Grann Helge
Pedersen Carsten H.
Vedsted Per Frost
Grundfos A/S
Jacox Meckstroth & Jenkins
Knight Anthony
Patel Vishal
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