US3396906A

US3396906A - Pump housing seal arrangement

Info

Publication number: US3396906A
Application number: US703447A
Authority: US
Inventors: Earl W Newton
Original assignee: Trane Co
Current assignee: Trane US Inc
Priority date: 1968-02-06
Filing date: 1968-02-06
Publication date: 1968-08-13
Anticipated expiration: 1985-08-13

Description

Auj. 13, 1968 E. w. NEWTON I 3,396,906

PUMP HOUSING SEAL ARRANGEMENT Filed Feb. e. 1968 I 2 Sheets-Sheet 1 INVENTOR.

EARL W. NEWTON ATTOR NEY Aug. l3, 1968 E. w. NEWTON PUMP HOUSING SEAL ARRANGEMENT 2 Sheets-Sheet 2 Filed Feb. 6. 1968 FIG. 8

FIG. 5

FIG. 6

FIG?

INVENTOR. EARL W. NEWTON BY M ATTORNEY United States Patent- 3,396,906 I PUMP HOUSING SEAL ARRANGEMENT Earl W. Newton, La Crosse, Wis., assignor to The Trane Company, La Crosse, Wis., a corporation of Wisconsin Filed Feb. 6, 1968, Ser. No. 703,447 7 Claims. (Cl. 230127) ABSTRACT OF THE DISCLOSURE A centrifugal compressor has a cast housing embodying a gas collecting scroll-shaped chamber terminating in the form of a conical diifuser at the compressor outlet. The housing is split along a plane normal to the axis of the compressor axially coextensive with the scroll-shaped chamber and conical diffuser so that no large scrollshaped cores are required to cast the scroll-shaped chamber in the housing. The discharge duct is connected to the compressor outlet. Both the housing shells and the discharge duct are provided with gasket supporting webs traversing the scroll-shaped chamber and duct respectively at the outlet. The first gasket, located between the housing shells, passes between the webs of the shells while a second gasket, located between the duct and the housing outlet, passes between the web of the duct and the webs of the shells. Each gasket lies in its own plane which intersects the plane of the other gasket. However, these gaskets need not be in contiguous relation to effect a complete seal, thereby eliminating one of the major causes of leaks in compressors having split discharge outlets.

Background of the invention This invention relates to compressors and the like and particularly to centrifugal compressors used in sealed refrigeration systems for compressing refrigerant gases. In compressors of this type, it is common practice to provide a gas collecting volute or scroll-shaped chamber circumjacent the centrifugal impeller. The chamber collects the gas discharged from the impeller. This chamber is cast into the housing of the compressor. The housing is normally split to permit assembly and installation of the impeller therewithin.

To simplify the seal in the area of the-compressor discharge outlet,it is common practice to form the scrollshaped chamber entirely within one of the split housings. However, in order to cast this chamber into one of the split housings, it is necessary to use a large spiral core which adds substantially 'to the cost of the housing. The core is diificult to remove and it is further difiicult to clean and inspect the internal surface formed thereby. The spiral core may of course be eliminated if the compressor housing is split along a plane coextensive with the scroll-shaped chamber. In this case the scroll-shaped chamber is formed by a spiral groove in each split portion of the housing. These grooves, being open at one side, may be formed by the casting mold without the use of a spiral core. It is relatively simple to clean, polish and inspect the groove surfaces.

Compressor housings constructed in this manner are known to the art. However they present a particular seal 1 problem as the split in the housing bisects the discharge opening. The gasket seal between the housing and the discharge pipe would normally be disposed in perpendicular contacting relation with the gasket seal between the split housing portions. These gaskets which lie in intersecting planes must be broughttogether in pressure contact to effect an adequate seal for refrigeration system use. This isdifiicult to achieve and is a major cause of leaks.

Summary of the invention The present invention permits a centrifugal compressor to be constructed with a split housing wherein the split is coextensive with the scroll-shaped gas collecting chamber therein without creating the seal problems normally encountered with such split housing construction. This is accomplished by the use of several seal supporting webs arranged to traverse the scroll-shaped chamber outlet. By the use of such webs, the gasket disposed between the housing shells and the gasket between the discharge duct and the compressor housing discharge outlet need not be in contacting relation, thereby substantially simplifying the seal and reducing the leak potential.

It is thus a prime object of this invention to provide a centrifugal type pump with a lower cost housing.

It is another object to provide a centrifugal type pump with a split shell wherein the chamber for collecting fluid discharge from the impeller is formed into both split portions.

A further object of the invention is to provide an improved seal arrangement for a split discharge outlet of a centrifugal pump housing.

Specifically this invention involves a shaft mounted for rotation about a central axis; a centrifugal impeller drivingly connected to said shaft and arranged to be rotated about said central axis; a housing means circumscribing said impeller and defining a scroll-shaped chamber therewithin which is disposed radially outward of said impeller for collecting fluid discharged from the periphery of said impeller; said housing having a fluid inlet and a fluid discharge outlet; the radially outer end of said scrollshaped chamber terminating at said discharge outlet; said housing being split generally along a plane normal to said axis axially coextensive with said scroll-shaped chamber and being comprised of first and second shells; a spiral groove in the inner face of each of said shells for defining said scroll-shaped chamber therebetween; each of said shells having a web bridging across the respective groove therein adjacent the discharge outlet end of said scroll-shaped chamber and having a face substantially coplanar with the radially outer rim of said groove; an annular gasket means interposed between the radially outer rims of said grooves and bridging across said grooves through the discharge end of said scroll-shaped chamber interfacially between said webs; an annular duct having one end thereof overlying and in communication with the ends of said grooves adjacent the discharge outlet; a web internally traversing said annular duct and said second gasket means extending between the web of said duct and the webs of said shells.

Other objects and advantages will become apparent as this specification proceeds to describe the invention with reference to the drawings wherein like reference numerals have been used to designate like elements throughout and in which:

FIGURE 1 is an end elevation of a compressor embodying the invention with a small portion broken away at the compressor outlet;

FIGURE 2 is a side elevation of the compressor shown in FIGURE 1;

FIGURE 3 is a vertical section taken at line 33 of FIGURE 1;

FIGURE 4 is a vertical section taken at line 4--4 of FIGURE 2 showing one compressor shell;

FIGURE 5 is a vertical section taken at line 55 of FIGURE 2 showing the other compressor shell;

FIGURE 6 is an enlarged section taken at line 6-6 of FIGURE 1 showing the compressor outlet;

FIGURE 7 is an enlarged section taken at line 7-7 of FIGURE 1 showing an end face of the compressor outlet duct; and

FIGURE 8 is a greatly enlarged section taken at line 88 of FIGURE 1 showingthe gasket supporting webs and particularly showing that upstream and downstream edges thereof having been rounded for aerodynamic efficiency.

Now referring to the drawing there is shown a contrifugal refrigeration compressor 10 having shaft 14 supported by suitable bearings (not shown) for rotation relative to housing 12 and rotatably driven by motor 16. A centrifugal impeller 18 disposed within housing 12 is carried by one end of shaft 14 for rotation. therewith.

Suitable keys (not shown) may provide the driving connection between motor 16 and shaft 14 and between shaft 14 and impeller 18.

Housing 12 is split into two

shells

20 and 22 which are connected together via bolt flanges 24 in order to permit impeller 18 to be installed therebetween. Impeller 18 has a plurality of radially extending passages 26 which extend from an impeller inlet 28 to an impeller outlet 30 at the periphery thereof.

Housing shell 22 has a central inlet opening 32 disposed in communication with impeller inlet 28. Inlet 32 may be connected to the suction line leading from an evaporator outlet (not shown) for withdrawing refrigerant gas from the evaporator.

A scroll-shaped chamber 34 formed by and disposed within housing 12 between

shells

20 and 22 is arranged in circumjacent relation with impeller 18. Housing 12 has a discharge outlet 37 to which the radial outer end of scroll-shaped chamber 34 is connected. This portion of chamber 34 adjacent outlet 37 is shaped to define a conical diffuser at 41. The inner walls of housing 12 are sufliciently spaced at 35 in thearea between the periphery of impeller 18 and the scroll-shaped chamber 34 to permit refrigerant gas discharged from the impeller outlet 30 to pass radially outward into scroll-shaped chamber 34.

Scroll-shaped chamber 34 is formed by a spiral groove 36 in the inner surface of each of

shells

20 and 22. This groove is formed in each of

shells

20 and 22 by a casting process. It will be evident to those having skill in the art of foundry practices that grooves 36 maybe formed by either the cope or drag portions of the mold and that no spiral core is required.

Each of spiral grooves 36 extend to discharge outlet 37. Each of

shells

20 and 22 has a web 38 which crosses the respective groove 36 adjacent discharge outlet 37.

Webs 38 are parallel to a plane perpendicular to the axis of shaft 14 and have a surface 39 coplanar with the radially outer rim 40 of corresponding groove 36 Thus the outer rim 40 and the surface 39 of web 38 of each shell presents a planar annular. surface. These planar annular surfaces of

shells

20 and 22 are allochiral. A shell gasket 42 of annular configurationdisposed between the allochiral surfaces seals

shells

20 and 22 together when the bolts on bolt flanges 24 are tightened. Gasket 42 may be of the hard flat type as shown or of the circular cross section type commonly referred to as an O-ring. Also, the flat type gasket may becomprised of several segments of flat gaskets placed end to end with dovetailed end joints to eliminate leakage. If an O-ring gasket is used, a groove must be formed in at least one of the planar annular surfaces of the

compressor shells

20 and 22 to accommodate the gasket and retain the same in position.

After the

shells

20 and 22 are assembled and bolted together at flanges 24, the outer surface of discharge outlet 37 including the downstream side of webs 38 is ground or otherwsie machined to present a plane surface to which the annular discharge duct 43 may be connected 4 via discharge outlet flanges 44 on

shells

20 and 22 and annular flange 46 on duct 43.

Duct 43 has a web 48 traversing internally thereof and disposed at the end of the duct adjacent the compressor housing discharge outlet 37. Web 48 is positioned to overlie the downstream ,sides of webs 38. The upstream side of web 48 maybe ground or otherwise machined in coplanar relation with the compressor end of duct 43. The downstream side of web 48 and the upstream sides of webs 38 may be rounded as shown in FIGURE 7 for reducing their flow resistance to fluid discharged from the compressor outlet. Duct web 48 and shell webs 38 may be integrally cast with the duct and shells respectively by the use of a small core or the webs may be constructed. as separate elements welded or otherwise sealingly positioned in place.

Webs

48 and 38 have sufficient thickness to adequately support and compress a gasket for effecting a seal.

An annular gasket 50 is disposed between the

flanges

44 and 46. Annular gasket 50 has a central web 52 which extends interfacially between duct web 48 and shell webs 38 (see FIGURE 8). When the bolts between

flanges

44 and 46 are tightened gasket 50 completely seals the compressor end of duct 43 to the compressor discharge outlet 37. The web portion 52 of gasket 50 prevents leakage via the space 54 (FIGURES) extending transversely through the discharge outlet outwardly of gasket 42 between webs 38 to the atmosphere. It will thus be seen that gasket-

s

42 and 50 lie in separate planes and are spaced'one from the other by space 54. With the above described web and gasket structure, there is no necessity to force plural gaskets disposed in intersecting planes together into contacting relation for effecting the seal thereby eliminating one of the major causes of leaks in prior art split volute compressors.

Having thus described in detail the preferred embodiment of my invention, I contemplate that many changes may be made Without departing from the scope or spirit of my invention and I accordingly desire to be limited only by the following claims. 1

I claim:

1. A centrifugal pump comprising in combination: a shaft mounted for rotation about a central axis; a centrifugal impeller drivingly connected to said shaft and arranged to be rotated about said central axis; a housing means circumscribing said impeller and defining a scrollshaped chamber therewithin which is disposed radially outward of said impeller for collecting fluid discharged from the periphery of said impeller; said housing having a fluid inlet and a fluid discharge outlet; the radially outer end of said scroll-shaped chamber terminating at said discharge outlet; said housing being split generally along a plane normal to said axis axially coextensive with said scroll-shaped chamber and being comprised of first and second shells; a spiral groove in the inner face of each of said shells for defining said scroll-shaped chamber therebetween; each of said shells having a web bridging across the respective groove. therein adjacent the discharge outlet end of said scroll-shaped chamber and having a face substantially coplanar with the radially outer. rim of said groove; an annular gasket means interposed between the radially outer rims of said grooves and bridging across said grooves through the discharge end of said scroll-shaped chamber interfacially between said webs; an annular duct having one end thereof overlying and in communication with the ends of said grooves adjacent said discharge outlet; a web internally traversing said annular duct and having a surface generally coplanar with said one end of said duct and overlying each of the webs of said shells; and second gasket means disposed between the said annular duct and said shells adjacent said discharge outlet; said second gasket means extending between the web of said duct and the webs of said shells.

2. The apparatus as defined by claim 1 wherein said scroll-shaped chamber has a generally circular cross section.

3. A centrifugal pump comprising in combination: an impeller mounted for rotation about an axis; a housing circumjacent said impeller and having a discharge outlet; said housing being split into two shells generally along a plane normal to said axis axially coextensive with said impeller; each of said shells including a spiral groove in the inner face thereof disposed about said impeller and in fluid communication therewith for receiving fluid discharged from said impeller; each of said grooves terminating at said housing discharge outlet; said spiral grooves being continguous along a plane normal to said axis, each shell having a gasket supporting web extending across its respective spiral groove adjacent the terminal portion thereof along a plane generally normal to said axis; an annular gasket means interposed between said shells circumjacent the radially outer edges of said grooves and passing across said grooves interfacially between said webs.

4. The apparatus as defined by claim 3 further including an annular duct connected at one end to said discharge outlet of said housing overlying and communicating with the ends of said grooves; said duct including a gasket supporting web internally traversing said annular duct and having a surface generally coplanar with said one end of said duct and overlying each of the webs of said shells; and second gasket means disposed between said one end of said duct and said shells; said second gasket means extending interfacially between the web of said duct and the webs of said shells.

5. The apparatus as defined by claim 3, wherein edges of said webs are rounded to reduce the flow resistance of fluid passing said webs.

6. The apparatus as defined by claim 3, wherein said shells are castings and said Webs are cast integrally with said shells.

7. Apparatus comprising: a hollow housing; means defining an opening in said housing in fluid communication with the interior of said housing; said housing being split into two concave shells substantially along a plane bisecting said opening; each of said shells having a gasket supporting member bridging the sides of said opening; each of said bridging members having a gasket supporting surface substantially coplanar with said plane bisecting said opening; a gasket means disposed between the rim of said shells and between the gasket supporting surfaces of said bridging members; and means biasing said shells toward each other and said gasket supporting members toward each other.

References Cited UNITED STATES PATENTS 2,311,024 2/ 1943 Buchi 230-127 2,801,043 7/1957 Spotz et al 230-133 3,266,428 8/1966 Feith et al. 103-114 2,117,011 5/1938 Pratt 103-114 HENRY F. RADUAZO, Primary Examiner.