Rotary kinetic fluid motors or pumps – Bearing – seal – or liner between runner portion and static part
Reexamination Certificate
2000-06-09
2002-08-13
Kwon, John (Department: 3754)
Rotary kinetic fluid motors or pumps
Bearing, seal, or liner between runner portion and static part
C384S540000, C384S906000
Reexamination Certificate
active
06431826
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a centrifugal pump with an impeller arranged in a pump housing, which impeller can be driven by way of a shaft, and the shaft is rotatably held in the pump housing by way of at least one bearing, with the bearing, which is preferably arranged as a roller bearing, being arranged in a bearing holder, with the bearing holder being detachably connected with the pump housing.
In known centrifugal pumps the bearings and axial face seals are directly pressed into the pump housing during production. Pump housing and impeller are supplied as prefabricated units for the respective purpose. In the event of any damage to the bearing it is necessary to exchange the entire pump plus spiral housing. As the pump housing forms the bearing holder, it must be made of metal for the purpose of heat dissipation which has a disadvantageous effect on the amount of production work and the weight of the appliance.
DESCRIPTION OF PRIOR ART
Centrifugal pumps of the kind mentioned above have been disclosed by U.S. Pat. No. 5,409,350 A, FR 2 353 771 A1 and the U.S. Pat. No. 2,203,525 A. In the first two of the aforementioned specifications the bearing holder is connected with the pump housing by separate screws. The bearing holder is inserted into the pump housing from the impeller side. Since the fastening screws of the bearing holder are covered by the impeller, it is necessary to remove the impeller from the shaft for the disassembly and assembly of the bearing holder.
In U.S. Pat. No. 2,203,525 A the bearing holder is inserted into the pump housing from the impeller side and fastened on the pump housing on the side averted from the impeller by a union nut. This design per se would allow removing the bearing holder plus impeller from the pump housing. In order to loosen the union nut it is necessary, however, to previously dismount the parts of the device which are on the side averted from the impeller such as drive wheel, drive motor or the like. FR 937 265 A also shows a similar design.
SUMMARY OF THE INVENTION
It is the object of the present invention to avoid such disadvantages and to provide a centrifugal pump which is easy to produce and service.
This is performed in accordance with the invention in such a way that the bearing holder, at the end facing the impeller, comprises an assembly part which is preferably integrally designed with the pipe section. A very simple disassembly of the bearing holder which is inserted into the pump housing from the impeller side is enabled by the assembly part. The actuation of the assembly part is particularly preferably possible even when the impeller has been inserted.
The bearing holder is used for receiving the bearing and for dissipating the bearing heat. The pump housing per se can be made of any desirable material, e.g. aluminum, magnesium or even of plastic. It is preferably provided that the bearing holder is provided with a substantially cylindrical pipe section for receiving the bearing. The inside jacket of the pipe section is provided with a press or loose fit and is used for receiving the bearing. The pipe section is additionally used to carry off leakages. It is provided for this purpose that the inside jacket of the pipe section is at least provided with one leakage duct arranged as an axial groove. In order to enable the discharge of the leakages irrespective of the installed position of the pipe section, it is particularly appropriate to provide the inside jacket of the pipe section with several leakage ducts which are evenly distributed over the circumference and arranged as axial grooves.
It can further be provided that a sealing element, preferably an axial face seal, is pressed into the bearing holder in the zone of the impeller-side end of the bearing holder. It is preferably provided that the bearing holder is provided with a collar in the transitional region between pipe section and assembly part onto which the sealing is pressed.
At the impeller-side end, the bearing holder is sealed off from the receiving zone of the pump housing by sealing means. The bearing holder is further provided with a support collar in the zone of the impeller-side end, up to which the bearing holder is pushed onto the pump housing. The sealing means, e.g. an O-ring seal, a sealing lacquer or microencapsulation of the screw thread, can ensure the protection against torsion. Protection against torsion can also be provided by a surface knurling of the face of the support collar of the bearing holder against the receiving area of the pump housing.
In a particularly preferable embodiment of the invention it is provided that the pipe section is provided with a thread on its outside jacket. The bearing holder is screwed into the receiving zone of the pump housing by way of a thread, thus producing a secure, but still detachable connection between the bearing holder and the pump housing.
In order to ensure a particularly simple assembly and disassembly, it is provided that the assembly part preferably comprises a positive-locking zone, formed by a hexagon, as a working surface for a tool, with the smallest distance of the positive-locking zone from the shaft axis being larger than the largest radius of the impeller. The profile of the assembly part is thus substantially adjusted to the profile of the impeller in order to reduce clearance volumes to a minimum. It can be provided in an impeller with flow conduits which are inclined with respect to a normal plane from the rotational axis that the assembly part is provided with a face surface which is inclined towards the pipe section with respect a normal plane from the shaft axis.
In a further, highly preferably embodiment it is provided that the outside jacket of the pipe section is provided with a press fit and the bearing holder is pressed into the cylindrical receiving zone of the pump housing. The bearing holder is pressed in this process into the cylindrical receiving zone of the pump housing right up to the limit stop formed by the support collar. Instead of a press fit it is possible that the outside jacket of the pipe section is provided with a loose fit and is torsionally secured against the pump housing by way of a securing screw. In order to allow the attack of pressing or pushing tools on the bearing holder, it is provided that for the purpose of assembly of the bearing holder several axial mounting openings are formed in the impeller, preferably in the zone of the support collar, and the mounting openings are sealed off by sealing means. Sealing lacquer can be used for instance as a sealing means for the mounting openings. Any later disassembly of the bearing holder can be performed by means of suitable withdrawal tools.
It is particularly favorable when the pump housing receiving the bearing holder is formed by the spiral housing of the centrifugal pump.
The invention can be employed highly advantageously in a centrifugal pump for an internal combustion engine, which pump is arranged as a coolant pump and in which the spiral housing is arranged integrally with the oilpan. The oilpan plus spiral housing can be produced independent from the remaining elements of the centrifugal pump. The shaft, the bearing and the impeller are prefabricated and assembled, and are screwed or pressed into the spiral housing of the oilpan as a unit. In the case of any damage to the bearing or impeller in the course of the service life, only the pump unit consisting of bearing holder, bearing, shaft and impeller needs to be changed, but not the spiral housing formed by the oilpan.
The bearing holder leads to the advantage that there is considerable freedom in the production and the selection of material for the spiral housing, so that the spiral housing can be made integrally with the other parts of the machine from any desired material.
REFERENCES:
patent: 2203525 (1940-06-01), DuPree, Jr.
patent: 3711218 (1973-01-01), Kennel et al.
patent: 4917511 (1990-04-01), Katsube
patent: 5186068 (1993-02-01), Heller
patent: 5409350 (1995-04-01), Mitchell
patent: 5715976 (1998-02-01
Dykema Gossett PLLC
Kwon John
TCG Unitech Aktiengesellschaft
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