US2634685A - Improvement in the construction of outlet guide devices for centrifugal pumps or blowers - Google Patents

Description

A. BUCHI 2,634,685 ROVEMENT IN THE CONSTRUCTION OF OUTLET GUIDE DEVICES FOR CENTRIFUGAL PUMPS OR BLOWERS 4 Sheets-Sheet l w w 3 9 5 1 9 l m 4 1 a ALFRED BUCHI 2,634,685 LET GUIDE ERS April 14, 1953 A. BUCHI IMPROVEMENT IN THE CONSTRUCTION OF OUT DEVICES FOR CENTRIFUGAL PUMPS OR BLOW 4 Slgeets-Sheet 2 Filed Feb. 16, 1950 aflnununu HUDUDD J i 4 ALFRED BUCHI April 14, 1953 A BUCHI 2,634,685

IMPROVEMENT IN THE CbNSTRUCTION OF OUTLET GUIDE DEVICES FOR CENTRIFUG'AL PUMPS OR BLOWERS 4 Sheets-Sheet 3 Filed Feb. 16, 1950 Patented Apr. 14, 1953 2,634,685 IMPROVEMENT IN THE CONSTRUCTION OF OUTLET GUIDE DEVICES FOR CENTRIFU- GAL PUMPS OR BLOWERS Alfred Buchi, Winterthur, Switzerland Application February 16, 1950, Serial No. 144,408

2 Claims.

This invention relates to improvements in the construction of outlet guide devices for centrifugal pumps and blowers, such as are described in my United States Patent No. 2,596,646.

The unusual shape and arrangement of such guide-devices render their manufacture by recognized methods exceedingly difficult and costly. Thus, conventional sand casting of these devices produces inner walls which are relatively rough. In pumps or blowers productive of high gas or fluid velocities, such roughness in the guidedevices tends to affect seriously the efiiciency of the machines. It becomes necessary, therefore, to attempt to smooth and polish the inner walls of the sand cast guide-devices. This is a difiicult task, however, as will be obvious from a study of the shaping and arrangement of such devices in a blower or pump casing.

My invention consists of a construction of such guide-devices and arrangements thereof within a casing whereby guide duct walls are prefabricated of relatively thin-walled sheet metal material at least for the inner parts of the ducts through which the pressure medium is passed at high velocity, and in which such velocity is transformed at least partly into pressure; such prefabricated walls are then set into position with moulds for the housing; and casting material is thereupon poured to form integrally with the prefabricated walls, the desired housing and guidedevices.

By this construction the important guide ducts may be provided with the best possible surfaces by pressing, bending, welding, machining, etc. the thin-walled sheet material prior to its being cast in the housing moulds.

The design may be such that the inner individually prefabricated guide-device parts are rigidly joined together in an arrangement to con stitute a single piece or several pieces before they are cast into the other part or parts of the bloweror pump-housing.

The inner individually prefabricated guidedevice parts may be cast-in as parts separated by a plane normal to the axis of the machine with likewise separated cast housing parts. It is also a part of my invention to fabricate the guidedevice insert parts with edges which protrude over the final separating plane and the surface of the cast casing parts so as to prevent any overflow of the liquid casting material into the ducts during the pouring stage of the casting operation. These guide-device parts may also be provided with temporary partition walls to close their normally open apertures in order similarly to prevent the liquid casting material from flowing Switzerland February 17, 1949 into the ducts during the pouring operation. After setting, the temporary partition walls are removed.

Furthermore, cores consisting of metal or sand o similar material may be provided inside the guide part inserts for cooling and reinforcing them when they are heated during the casting operation. Such cores may also be equipped with special cooling devices.

Figs. 1-12 illustrate several executions of my construction. I

Figs. 1-3 illustrate an execution of the invention in which a prefabricated guide-device is disposed in two housing parts, separated by a plane containing the axis of the machine. Fig. 1 is a side-view of the separate housing parts viewed in the direction of the arrow shown in Fig. 2. Fig. 2 is a section through the axis of the separate housing parts indicated by the line II--II in Fig. 1. Fig. 3 is a section through a duct of the guide device taken along the line III-III in Fig. l, as a straight projection.

Figs. 4-6 show an execution of the invention inwhich the prefabricated guide-device comprises two parts separated by a plane transverse to the machine axis. Fig. 4 is a fragmentary elevation of the separating plane as viewed in the direction indicated by the arrow in Fig. 5. Fig. 5 is a.

section through the axis of the machine according to the line V-V in Fig. 4. Fig. 6' illustrates a section through a guide-duct according to the line VI-VI in Fig. 4, as a straight projection.

Figs. 7-9 illustrate a housing and guide-device in which the individual guide-device parts and housing are also separated by a plane transverse to the machine axis. These illustrations, however, show the appearance of the parts and hous ing after the casting-in operation and prior to their being finished and assembled as shown in Figs. 4-6. Fig. 7 is an elevation of the separating plane as viewed in direction of the arrow indicated in Fig. 9. Fig. 8 is an axial section through one half of the guide-device part along the line VIII-VIII in Fig. 7. Fig. 9 is a section taken on the same plane as Figure 8, but looking in the opposite direction.

Fig. 10 shows according to Fig. 8 the placing of cores in the inserts and other portions of the ducts, and also hollow portions by a section through the casting box with the moulds and the inserts properly placed and after the casting material has been poured.

Fig. 11 shows according to Fig. 9, in a similar section to that shown in Fig. 10, cooling devices placed in the inserts. Fig. 12 shows, in a part section of that shown in Fig. 9 or 11, the application of metal plating designed to fuse with the casting material.

In Figs. 1 to 8, the reference characters I and 2 designate the two halves of the housing which contain the guide-device. The impellor rotor 3 is shown'within the housing rotatably mounted upon a :shaft 8. 54 'designatesthe. ducts of the guide-device. The fluid velocity produced by the rotor 3 is transformed into pressure in the ducts 4. My present invention calls for, .prefabricatin special walled-inserts 5 to formsductsfl. These inserts are made individually and to' very accurate dimensions and shapes by pressing, bending, welding, machining etc. thin sheet material. These prefabricated inserts 5 protrudewith their open portions 6 over the side walls of the housing parts I and 2 and are cast in this condition into the parts of the housing. This serves the purpose of preventing theliquid casting material from .flowing into these insertsduring the pouring process. -Af-ter .-the.casting operation iscompleted, the parts 6 which protrude beyond the width-of the housing are cut to their final planar condition coincident with that of the surface of the cast housing.

Each insert 5 which forms a duct '4 is brought together with adjacent inserts 5 at the edges 1 in such a manner as to form an accurately arranged guide-device. upon which no further shop work need be performed to obtain properly dimensioned and shaped ducts. Moreover, the arrangement is-such-as to prevent the liquid castingmaterial from flowing over into the ducts.

. Prior to the casting-in operation, the inserts 5 may be joined together to constitutea single piece including all guide ducts 4.

In .Fig. 3, 51is the thin-walled insert for the housing part 2. The manner in which the insert 5 protrudes beyond the housing at 6 previous to the finishing operation is also shown.

In preparation for the casting operation, cores of sand or'metal may be placed in the inserts 5 for cooling and as reinforcement of the inserts.

In- Figs. 4, 5 and 6, the reference numerals I and. 2' designate the housing parts of the guidedevice, which parts are. formed as castings. 3' is the rotor or impellor driven by the shaft-8. 4' are the ducts of the guide-device shaped as diffusers. In these ducts the velocity imparted to the fluid by the rotor 3 is transformed into pressure. 5"arethe prefabricated inserts which consist of-thin-walled material and have been produced before the casting-in operation as parts of the housing. 9 is the scroll case with the discharge connection [0 shownin dash dottedxlines. The. guide ducts 4 enter inlateral direction into the 'openings I l. of the scroll case.

In theFigs. 4-6 all parts areshown finished and in assembled condition. I

InFigs. 7-9, the numbers I and 2" designate the two castings which form the housing parts containing'at least part of the guide ducts 4".

The two thin-walled inserts 5" which form the ducts 4" protrude over the side walls at 8" of the parts I" and 2''. These protrusions of the inserts. 5" are provided for the purpose already mentioned of preventing the liquid casting material during the casting process from flowing into the inside'of the .inserts. After the casting operation, the parts I" and 2" are machined and finished in the manner illustrated in Figs. 4-6.

Fig. 7 indicates in dash-dotted lines how the apertures of the inserts 5 casting operation by sheet .83 also to prevent the flow are closed before the metal partitions l2, of casting material into the inside of the ducts. It is evident that Without these partitions the inner surface of the inserts 5" would be spattered with casting material. This possibility is eliminated by closing the apertures of the inserts in the fashion described. A cooling arrangement for individual guide-devices may be provided also as is indicated by dotted lines in Fig. 7. I6 is the inlet and I9 the outlet of the cooling pipe [7, I8.

In Fig. 10 the cast housing 2" conditioned in the two-part and firmly bolted together casting box 25, 26 designates the moulds 2'! and 28. The prefabricated insert 5" forms a part of the mould 28, and is anchored to the insert by temporary ties or anchors 29. The inserts 5 are also filled at IS with moulding material, providing for reinforcement of the comparatively thin sheet metal material of which the inserts are made. At 20 a distinct core of moulding material for forming the guide-device portion is shown, but one which is not lined by the prefabricated insert. 2| is also a distinct core which forms the hollow spaces of the casing 2" which has just been poured. The moulds 2'! and 28 may be made of any suitable material such as sand, iron, etc. The liquid casting material is poured through the opening 30 in the casting box, at suitable places. At 3| an overflow for the liquid casting metal is arranged, so that a certain maximum level of the liquid metal is guaranteed. The casting material may be poured .under artifical pressure condition or just ordinarily, or in any other fashion. At 24 a screw is shown in condition to keep the two- part casting box 25, 26 rigidly closed during the pouring operation.

The cores may include a special coolingdevice. This is shown in Fig. 11 whereat IS the feed piping for the cooling medium is indicated. The cooling is indicated by pipes l7, l3 placed within the inserts. continuous circulation of the cooling medium. For this purpose to I8 may be provided for continuous circulation which is indicated in Fig. 7 by a small arrow.

r The cooling medium is leaving the pipe 18 via the pipe connection I9.

The characters used in Figs. 10 and 11 relate more particularly to .the'execution of guide-devices built as described in Figs. 7-9. They are, however, drawn to the principle involved and appertain also to the executions of guide devices described in theFigures 1 to 3' and 4' to 6.

During casting, duct portions and other hollow spaces which are not lined by. the inserts 5" are filled out with cores of sand, metal or similar material, see Figure 10. The inside of the/inserts 5" may also be filled with. cores of metal, sand or similar material to cool and to support the walls of the inserts during the casting -operation. Also separate cooling devices referred to and shown in Figs. 11 and 7 may be built'into said cores to provide additional coolingof the in serts during casting.

The main advantage proffered by this invention is the elimination of the necessity of performing additional shop work after the. casting.

operation to attain accurately dimensioned ducts for the guide-devices. Moreover, the inserts 5. 5 and5" are initially provided with smooth inner surfaces. They are also prefabricated :and produced individuall by accurate tools facilitating their manufacture to precise dimensioning.

If necessary, may be further improved after they have been cast-in the'housing,

The arrangement provides for means to connect the pipes H;

the inner surfacesof the inserts e. by rinding or polish-1' ing, etc. However, if the'inserts 5, 5', 5" are properly and carefully prefabricated, no further elaborate inside finishing work should be necessary.

The prefabricated cast-in guide-device is preferably provided on its surface which is to protrude into the casting with a coating which is capable of fusing with the casting material. Such fusing tends to establish undetachable rigid integral contacts of the guide-devices with the housing or casing. This coating may consist of metal plating, such as copperand/or tinplating. This is shown in Figure 12, designating at 32, said coating on the surface of the prefabricated inprotruding into the cast housing part I", and fusing with its material, when pouring it into the mould. Fig. 12 is a partial enlargement of the section shown in Fig. 9.

I claim:

1. As an article of manufacture, a housing for a rotatable blower wheel adapted to discharge pressure fluid centrifugally outwardly from the blower wheel axis, said housing comprising two halves of cast material divided along a plane substantially normal to the rotor axis and passing through the blower wheel, the mating sides of each of said halves being shaped to provide a portion of each of a series of guide duct diffuser walls and of a receiving scroll wall, said diffusers originating in the vicinity of the periphery of said blower wheel and being disposed to continue the fluid in the direction of its discharge from the blower wheel for at least some distance, thereafter delivering the fluid into the scroll, and a smooth-walled metal liner inserted in that area of each portion of the guide duct diffuser wall beginning at the fluid entrance where its velocity is highest and continuing for some distance thereafter until a substantial conversion of fluid velocity into pressure has taken place, the said portions so forming the guide duct diffuser walls and receiving scroll and the smooth-walled metal liner in each housing half being further so disposed and of such extent as to register with the corresponding wall and scroll forming portions and liner in the other housing half when the two halves are brought together along said, plane, thereby to completely define a series of guide duct difiuser passages and scroll, and means for securing said halves together in such registry.

2. The housing as defined in claim 1 wherein all the metal liners inserted in one of the halves of cast material are secured together.

ALFRED BUCl-II.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,234,878 Corvin July 31, 1917 1,286,654 Kralund Dec. 3, 1918 1,652,468 Catlin Dec. 13, 1927 1,799,991 Sellick et al. Apr. 7, 1931 1,934,239 Schupp Nov. 7, 1933 1,985,341 Fraser Dec. 25, 1934 1,989,996 Mautsch 1 Feb. 5, 1935 2,109,680 Neveling, Sr. Mar. 1, 1938 2,157,892 Godfriaux May 9, 1939 2,207,317 Gear July 9, 1940 2,224,337 Bostwick Dec. 10, 1940 2,227,500 Johnson et al Jan. 7, 1941 2,311,024 Buchi Feb. 16, 1943 FOREIGN PATENTS Number Country Date 240,220 Great Britain Sept. 24, 1925 955,464 France June 27, 1949

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