Patent Application
20050089397
The present invention pertains to the field of impeller pumps. More particularly, the present invention pertains to a system for adjusting the spacing between a thrust housing in a pump having an impeller and the frame of the pump, and so for adjusting the clearance between the impeller and a housing of the pump.
In a typical impeller pump—such as the Gould Model 3196 series of pumps produced by Gould's Pump, Inc., of Seneca Falls, N.Y.—a bearing housing/thrust housing and a bearing frame are two separate items attached to one another in spaced apart relation so as to have a desired spacing. The spacing in some such pumps determines the clearance between the impeller and a housing of the pump. The Gould Model 3196 (and also Model 3175 and 3180) are open impeller pumps, and include a system for adjusting the spacing between the thrust housing and bearing frame—and so the impeller clearance—that has now been in common use for over 30 years. A precise setting of impeller clearance is required to maintain pump efficiency.
The impeller clearance adjustment system used in these pumps is shown in
Some other adjusting arrangements involve shims between the thrust housing flange and the bearing frame. Such shim arrangements require that the pump be disassembled in order to adjust impeller clearance.
In addition, U.S. Pat. No. 5,951,244 to Knight, and also U.S. Pat. No. 6,368,053 also to Knight, describe an impeller clearance adjustment system that uses a plurality of pairs of adjustment bolts and mating attachment bolts to provide a desired spacing between thrust or bearing housing and a bearing frame (and so to provide impeller clearance adjustment). Both the thrust housing and the frame have evenly spaced apart pair-wise registerable threaded openings. A threaded adjustment bolt is threaded through an opening of the thrust housing and abuts the frame. The end of each adjustment bolt is squared and the cross section is greater than the cross section of each opening on the frame so that the adjusting bolt does not, and cannot, enter the opening of the frame. The adjustment bolt is dimensioned so that when each is fully inserted into its respective opening in the thrust housing, the impeller clearance is at the greatest desired distance. The attachment bolt is then passed through each aligned opening pair to hold the thrust housing to the frame. The '053 patent additionally describes a twinsert threadably installed in the threaded openings of the frame and also describes locking bolts each being threaded not into the frame itself, but instead into a twinsert (after being passed through a bore opening of a respective adjustment bolt). The holes in the flange of the thrust housing must be a sufficient size to accommodate relatively large diameter adjustment bolts so as to be able to have attachment bolts of sufficient diameter to provide reasonable strength. Since in some pumps the flange of the thrust housing is relatively small, such a design can be problematic.
It would therefore be advantageous to have an impeller clearance adjustment system simpler than the older above described system using both jack bolts and locking bolts, but also one able to provide a stronger attachment of the thrust housing to the frame, especially in case of a relatively small flange on the thrust housing.
Accordingly, in a first aspect of the invention, an apparatus is provided, comprising: a two-housing assembly including a first housing having a plurality of first spaced apart non-threaded openings, and including a second housing having a plurality of second spaced apart threaded openings registerable with the plurality of first spaced apart non-threaded openings; and means for holding the first housing and the second housing in a desired spaced-apart relation including a plurality of adjustment screws each having a shoulder portion and each passing through one of the plurality of first spaced-apart openings and threadably passing into one of the second spaced apart threaded openings in the second housing so as to have the shoulder portion disposed between the first housing and the second housing and so preventing movement of the first housing toward the second housing closer than a desired spacing.
In accord with the first aspect of the invention, the means for holding the first housing and the second housing in a desired spaced-apart relation may also include a plurality of lock nuts each threadably engaging a respective adjustment screw so as to lock the adjustment screw against screwing into or screwing out of the first housing when tightened until it abuts the second housing.
Also in accord with the first aspect of the invention, the first housing may have a flange and may have a recess in the flange for the shoulder portion of each adjustment screw suitable for accommodating all or part of the shoulder portion of the adjustment screw.
Also in accord with the first aspect of the invention, the apparatus may be a portion of a pump having an impeller, and the spaced apart relation may correspond to a spacing between the impeller and a suction housing.
Still also in accord with the first aspect of the invention, the shoulder portion may be formed as part of the attachment screw or may be provided as a separate washer or nut fixed in place on the attachment screw.
In a second aspect of the invention, a method is provided for holding a first housing and a second housing in a desired spaced-apart relation, comprising: a step of threading to a desired depth in a second housing a plurality of adjustment screws through a respective one of a plurality of threaded openings in the second housing; a step of pushing the first housing onto the plurality of adjustment screws so as to have each adjustment screw pass through a respective non-threaded opening in the first housing until a shoulder portion of each adjustment screw prevents further progress of the first housing onto the adjustment screw.
In accord with the first aspect of the invention, the method may further comprise a step of threading a plurality of lock nuts onto a respective one of the plurality of adjustment screws so as to lock the adjustment screw against screwing into or screwing out of the second housing when the lock nut is tightened up to the point where it abuts the first housing. The method may even further comprise a step of loosening the lock nuts, and screwing or unscrewing the attachment screws to a new desired depth in the second housing, and then re-tightening the lock nuts.
The above and other objects, features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with accompanying drawings, in which:
Referring now to
In first assembling an impeller pump so as to include the impeller clearance adjustment system provided by the invention, the shoulder screws are typically first screwed into threaded holes in the frame 12 so as to have a spacing 10 approximately of a desired size between the frame side of the shoulder 21a of each shoulder screw and the frame 12. The thrust housing 11 is then positioned so that holes in the thrust housing register with the shoulder screws 21, and the thrust housing is then pushed onto the shoulder screws until the shoulders 21a of the shoulder screws 21 stop the thrust housing from advancing further toward the frame 12. The lock nuts 22 for each shoulder screw are then generally screwed on but not tightened until a fine adjustment of the spacing 10 is made by turning the shoulder screw, which is adapted for turning by having either a hexagonal head, a square head, a socket head, or a screwdriver slot. Turning a threaded shoulder screw in combination with the respective lock nut (with the lock nut loose) will move the thrust housing 11 relative to the frame 12, and allow precise adjustment of the clearance between an impeller (not shown) and a housing (also not shown).
The shoulder 21a on the threaded shoulder screws 21 can be created as part of the shoulder screw 21 or can be provided as a separate washer or nut fixed in place on the screw.
Referring now to
Still referring to
The adjustment system provided by the invention combines into a single shoulder screw the function of the lock bolt 16 and jack bolt 14 (
The invention also provides greater strength compared to the more recent prior art using adjustment screw with a longitudinal bore hole through which is passed an attachment bolt (as in U.S. Pat. Nos. 6,368,053 and 5,951,244, both mentioned above), since the shoulder screw can be relatively larger than the attachment bolt in the above-referenced patents in case of a small flange because the shoulder 21a need not be large in order to perform its function of preventing the thrust housing 11 from moving any closer to the frame 12 than is desired.
Advantageously, the invention does not require any modification to the frame or thrust housing of impeller pumps currently using the older adjustment system, except that a counter bore on the thrust housing may be provided to allow full travel of the thrust housing during adjustment (but the counter bore is not required if adequate clearance between the frame and the thrust housing flange is sufficient to allow for full adjustment).
As is clear from the above description, nothing about the invention limits it to use with centrifugal pumps, and indeed the invention is of use on any housing that must be precisely adjusted, not only on housings of centrifugal pumps.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention, and the appended claims are intended to cover such modifications and arrangements.
