US3309009A - Refrigerating compressors - Google Patents

Description

March 14, 1967 cu 3,309,009

0 REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet 1 FIG! . mwrrw 7 77 W D a March 14, 1967 R. CULK 3,309,009

' REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet 2 March 14, 1967 R. CULK 3,309,009

REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet 5 March 14, 1967 R. CULK 3,309,009

REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet LL FIG. 4

United States Patent Ofiiice 3,309,009 Patented Mar. 14, 1967.

3,309,009 REFRIGERATING COMPRESSORS Raimund Culk, Varenaweg 1, Graz XI, Styria, Austria Filed Apr. 28, 1965, Ser. No. 451,465 Claims priority, application Austria, May 12, 1964, A 41,346/64 6 Claims. (Cl. 230-58) The invention relates to a refrigerating compressor with preferably vertically flange-mounted electric motor the rotor of which is located in overhang on the compressor shaft and is separated from its stator by a hood consisting of a thin-walled cylindrical part of chrome nickel steel surrounding the rotor with very little clearance, and a lid-shaped part forming the hood top, as well as a flange-like part forming the hood edge, wherein the hood and the stator housing are mounted via a supporting ring on the compressor housing.

For the perfect operation of electric motors with separating hoods it is essential that the cylindrical hood part between the rotor and the stator of these motors should be as thin as possible, because the efliciency and the cos value decline with increasing air gap whilst a thicker cylindrical hood portion causes higher eddy current losses if it is made from conducting material. In addition, the cylindrical hood portion must be sufliciently strong to resist the often high internal and external pressures. These factors have hitherto limited the size of motors equipped with such separating hoods.

The present invention has the object of enabling the separating hood also for larger electric motors'to be made economically whilst maintaining its resistance to high internal and external pressures and a high power factor.

There are already known electric motors for driving refrigerating compressors which are made in several parts and wherein both the thin-walled cylindrical portion within the zone of the rotor orstator parcel and the lidshaped portion forming the top of the hood are made from chrome-nickel steel. On the other hand, the thicker shell part forming the edge of the hood is made of ordinary steel and mounted directly in a centering face of the supporting ring on which is also mounted centrally the stator housing. The cylindrical part and the lid-shaped portion of the hood, forming the top are drawn on a press from a circular blank of chrome-nickel steel sheet, whereby, although the hood is given a high degree of rigidity, waste occurs already when stamping the circular blanks from rectangular steel plates. In addition, when drawing the hood, the material is often weakened and these weaknesses do not become apparent until the hood has been finished. Another drawback of these known designs of refrigerating compressors is that the supporting ring is a separate component, since the hitherto used iron rings had to be fully machined and connected by welding or soldering to the reinforced part forming the edge of the hood. Moreover, at this joint which must be absolutely gastight, leaks may occur which cause expensive repairs and interruptions in the manufacture. Especially where large numbers are produced, the production costs of the supporting rings, the machining time and the production of thejoints are of relevant importance.

According to another known construction, also proposed in connection with refrigerating compressors, the production costs are lowered in that only the thin-walled cylindrical part of the hood is a stainless steel, whilst the lid-shaped portion forming the hood top and the flanged reinforced part forming the hood edge are of non-magnetic material with a very high electric resistance. The thin-walled cylindrical hood portion is made from a suitably cut sheet metal member which is bent to form a cylinder and welded along the edges in overlap. To enable this thin-walled cylinder to withstand the internal and external pressures, a supporting cylinder of magnetically conducting material is arranged therein, having the shape of a hollow body urging the thin-walled cylindrical part against the inner periphery of the stator parcel. However, the manufacture of this supporting cylinder,

' consisting of alternating laminated toothed heads and longitudinal insulating pieces, is very expensive and requires a specially constructed stator parcel so that stators of conventional electric motors cannot be used. Moreover, the reinforced part vforming the hood edge is not made of sheet metal but from a metal ring which must be fully machined which is difficult from the viewpoint of rational production. Also, the hood is not fitted to the compressor housing by a supporting ring, but directly by a screwed joint, causing misalignments between rotor and hood.

According to the invention, these drawbacks may be avoided in that the thin-walled cylindrical part has at its edge connected with the lid-shaped part a diameter which I is smaller than it inner diameter, and the flange-like reinforced part of the hood is formed integrally with the supporting ring and produced by drawing from sheet metal. 1

According to a further feature of the invention the lid-side end of the cylindrical hood portion is rounded off towards the longitudinal axis of the hood and connected directly with the edge of the lid-shaped part of the hood, e.g., by welding or soldering, on outer edge zone of the lid-shaped hood portion, which may be equipped with a shoulder that rests against the inner surface of the rounded end of the cylindrical hood portion,

wherein the edge of the rounded hood end is connected by welding or soldering with the other surface or with the shoulder of the lid-shaped hood portion.

This rounding off of the lid-side end of the cylindrical hood portion produces a high degree of rigidity of the cylindrical portion so that collapsing or bulging under high pressures is avoided even with thin-walled construction of the hood. This rounding off can be produced by means of a rolling tool which is cheap and raises the production costs only negligibly. Moreover, in order to lower the production costs yet further, both the flanged, reinforced hood portion and the supporting ring are made of one piece of sheet metal by drawing. To this end, suitable blanks are cut, for example from 4 mm. steel plate, the necessary centre recess is stamped out, and the prepared blanks are pressed on a drawing press into the required shape and finally equipped with the necessary mounting holes or the like.

According to a further feature of the invention, the flanged, reinforced part of the hood may have in its outer wall portion a dish-shaped recess and/or a rim. Also, this hood portion may be made in two parts wherein the outer ring of the divided hood portion is arranged in overlap on the inner ring and these two are mounted together on the compressor housing. Preferably, the ring shaped outer part is equipped with two centering lugs.

For producing a fully hermetic compressor construc tion, the outer edge or rim of the flanged reinforced hood portion may be connected to a sheet metal dish or tank surrounding the compressor housing.

The configuration of the reinforced part of the hood and of the supporting ring results not only in a substantial reduction in costs, but also reduces the overall weight and thus the carriage and transportation costs, whilst a high degree of strength and accuracy is achieved in spite of the cheaper sheet material, owing to the use of the drawing techniques.

The invention will be further described, by way of example, with reference to the accompanying drawings, showing several embodiments thereof, and in which:

FIG. 1 shows the separating'hood and the supporting ring in axial cross-section, viz., FIG. 1a and 1b showing further details of the hood;

FIGS. 2 and 3 show embodiments of the reinforced hood portion with vertical arrangement of the electric motor;

FIG. 4 shows an embodiment of the reinforced hood portion with horizontal arrangement of the electric motor.

According to FIG. 1, the separating hood 1 consists of a thin-walled portion 1, a flanged reinforced portion 1 and lid-shaped portion 1". The thin-walled hood part 1 is made of chrome-nickel steel, cut to rectangular or similar shape, bent and soldered or welded at the edges 21. In order to increase the rigidity, the lid-side end 4 of the part 1 is drawn in by means of a rolling tool so as to create a rounded off portion, the edge diameter d of which is smaller than the inner diameter D of the cylindrical part 1. The rounded off end 4 of the cylindrical part 1' is not machined and has its full wall thickness. On the other hand as seen in FIG. 2 between the stator 11 and the rotor 10, the cylindrical part is as thin-walled as possible. The edge of the lid-shaped hood portion 1" is connected by welding or soldering with the edge of the rounded off portion 4 of the cylindrical hood part 1' either directly (FIG. 1) or as shown in FIGS. la and 1b, in which the lid-shaped hood portion 1" rests with its edge zone '5 against the inner surface of the rounded off hood end 4, the edge of the head end being connected by soldering or welding to the outer surface of the part 1". The lid-shaped part 1" may have a shoulder (FIG. 1b) to which the edge of the rounded off hood end may be soldered or welded.

The flanged reinforced part 1" is formed integrally with a supporting ring 20 and is made by suitable tools by using drawing techniques. The outer edge zone, having the ring has either a dish-shaped recess 2 or a rim 3. Both may be provided as shown on the right side in FIG. 1. This recess 2 and/or rim 3 reinforces the part carrying the supporting ring 20 of the portion 1" so that even comparatively thin sheets may be used for the manufacture thereof.

FIGS. 2 to 4 show the assembly of the separating hood 1 according to the invention with piston compressors of various designs. FIG. 2 shows a single piston compressor whose housing 15 is centered through a shaft bearing 18 on the reinforced hood part 1" and connected thereto by screws 15. The outer edge of the recess 2 has holes 2 for the fixing screws 13 for the stator housing 12, which is equipped with cooling ribs 12' and carries the stator 11 Between the stator 11 and the rotor mounted on the compressor shaft 9 is the thin-walled hood portion 1'. The stator and its windings are covered by a hood 19.

On the right side in FIG. 2 there is shown a divided reinforced hood portion 1", consisting of an inner ring 7 and an outer ring 6, the latter overlapping the inner ring 7 and mounted together therewith by screws 15 on the compressor housing 15.

FIG. 3 shows a twin bearing two-cylinder refrigerating compressor, on whose separating hood 1 on the outer edge of the flanged reinforced hood part 1" is mounted a sheet metal dish 16 which fully encloses the compressor housing. This sheet metal dish 16 may also be welded to the outer edge of the hood portion 1" so that the compressor is fully hermetically and tightly enclosed in the vessel formed by the hood 1 and the sheet metal dish 16. As may be seen from the right side of FIG. 3, the recess 2 in the hood portion 1" may also be downwardly directed, wherein the stator housing 12 fests through retaining lugs 17 or a retaining ring on the hood portion 1" or its supporting ring 20 and is mounted together therewith by screws 15 on the compressor housing 15. In the embodiment shown in 'FIG. 3, left side, screw nipples 14 are welded to the outer edge zone of the hood portion 1 for mounting the stator housing 12 into which may be screwed bolts 13 arranged between the cooling ribs 12'.

FIG. 4 shows a two-cylinder refrigerating compressor with horizontally flange-mounted electric motor, whose rotor is mounted on the rotor shaft 9 and separated from the stator 11 by a thin-walled cylindrical hub portion 1.

The shaft bearing 18 is mounted by screws 18 on the compressor housing 15 whilst the separating hood 1 is centered on the end face 22 of the shaft bearing 18 and mounted by screws 15 on the compressor housing 15. In the embodiment of the reinforced hood portion 1" in FIG. 4, bottom, the same has a deep recess 2 with weldedon tongue-shaped lugs 8 for mounting the stator housing 12. The lugs 8 may also be bent out of the upper rim of the recess 2. Also a divided construction of the reinforced hood portion 1" is possible with horizontally flangemounted electric motor, as shown in the upper part of FIG. 4. This requires that the outer ring 6 be equipped both with a centering lug 6' for the inner ring 7 and with a centering lug 6" for the stator housing 12, because good alignment of all parts can be guaranteed only in this way. This divided construction is suitable especially for the use of commercial motors because the bearing plates of these motors can be easily replaced by an outer ring 6 formed by a heavy casting.

The invention is not restricted to the embodiments hereinbefore shown and described. In particular, the flanged reinforced hood portion may be stiffened by other embossings and further elements, such as lugs, may be provided on its outer edge for supporting or suspending the refrigerating compressor.

What I claim is:

1. A refrigerating unit containing a compressor having a housing and an electric motor drivingly coupled to said compressor, said electric motor including a stator, a stator housing and a rotor, the improvement comprising a hood composed of three joined sections; the first section being a thin-walled cylindrical part made of stainless steel interposed between said stator and said rotor and having at one end an inwardly converging annular portion defining an aperture of smaller diameter than the diameter of the cylinder; the second section being a lid joined to said first section to close said aperture; the third section being a drawn annular reinforcing member joined tothe other end of said first section and by which the hood and stator housing mounted on the compressor housing by securing means.

2. A refrigerating unit according to claim 1 wherein the said first section is metallurgically joined to the said second section.

3. A refrigerating unit according to said third section is formed with an integral outwardly extending flange portion.

4. A refrigerating unit according to claim 3 wherein said flange portion is shaped so as to define an annular recess. a

5. A refrigerating unit according to claim 1, wherein the said third section is formed of inner and outer reinforcing member portions arranged to overlap, and means are provided for securing both of said portions at their overlap to said compressor housing, the inner reinforcing member portions being joined to said first section and the outer portion being secured to said stator housing.

claim 1, wherein 6. A refrigerating unit according to claim 5, wherein 2,827,855 3/1958 Rankin 103-87 the said outer poition'carries a first centering lug for 00- 911 549 11 1959 Culk 310 35 operation with the inner portion and a second centering lug for co-operation with the said stator housing. FOREIGN TS 5 References Cited by the Examiner 957359 2/1950 France UNITED STATES PATENTS ROBERT M. WALKER, Primary Examiner.

1,233,569 7/1917 Graemiger 310-86

Claims (1)

1. A REFRIGERATING UNIT CONTAINING A COMPRESSOR HAVING A HOUSING AND AN ELECTRIC MOTOR DRIVINGLY COUPLED TO SAID COMPRESSOR, SAID ELECTRIC MOTOR INCLUDING A STATOR, A STATOR HOUSING AND A ROTOR, THE IMPROVEMENT COMPRISING A HOOD COMPOSED OF THREE JOINED SECTIONS; THE FIRST SECTION BEING A THIN-WALLED CYLINDRICAL PART MADE OF STAINLESS STEEL INTERPOSED BETWEEN SAID STATOR AND SAID ROTOR AND HAVING AT ONE END AN INWARDLY CONVERGING ANNULAR PORTION DEFINING AN APERTURE OF SMALLER DIAMETER THAN THE DIAMETER OF THE CYLINDER; THE SECOND SECTION BEING A LID JOINED TO SAID

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