US3141608A

US3141608A - Refrigerating machines

Info

Publication number: US3141608A
Application number: US240628A
Authority: US
Inventors: Enemark Arne Fromm
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 1961-11-28
Filing date: 1962-11-28
Publication date: 1964-07-21
Anticipated expiration: 1981-07-21

Description

July 21, 1964 A. F ENEMARK 3,141,603

REFRIGERATING MACHINES Filed Nov. 28, 1962 United States Patent "ice,

3,141,6h8 REFREGERATING MACHINES Arne Fromm Enemark, Sonderborg, Denmark, assignor to Danioss A/S, Nordhorg, Denmark, a company of Denmark Filed Nov. 28, 1962, Ser. No. 240,628 Claims priority, application Germany Nov. 28, 1951 4 Claims. ((31. 230-232) This invention is concerned with a motor compressor of the type used in small refrigerating machines, e.g., machines adapted to be enclosed in a hermetically-sealed capsule, and the invention is more particularly concerned with the compressor and related portions of such machines.

Refrigerating machines of the type used in domestic refrigerators are produced in large quantities and, therefore, structural simplifications and efficiencies can reduce production costs considerably. It has been proposed to unite components adapted to carry out different functions in a single unitary assembly e.g. by casting the motor support integrally with the cylinder, or by casting the cylinder with the muffler chambers.

It is an object of this invention to provide a construction which makes it possible to realize a major reduction in production costs.

According to the invention this object is realized in a component comprising at least the motor support and the cylinder integrally cast as a precision cast unit, the cast blank having holes for securing means and connecting channels so that further machining of the component is not necessary. Only a finishing treatment of the interior surfaces of the bearing and of the cylinder defined in the cast unit will be necessary. whereas it previously was necessary to carry out a number of Working procedures to obtain a finished component e.g. the boring of bearings, cylinder, all connecting channels, and holes for securing means, it is, according to the present invention, necessary to carry out only two working procedures, viz., polishing of the interior surfaces of the bearing and of the cylinder. The assembly line, on which all these procedures previously were carried out in an automatic sequence, can thus be shortened. Only one machine is necessary on which tools placed at right angles to each other carry out the polishing of the bearing and of the cylinder.

Thus, in accordance with the invention, not only are the number of working procedures substantially reduced, but general production costs are minimized through shorter travel time on the assembly line, and purchase, erecation, and maintenance costs are also substantially reduced.

Precision casting is well known and comprises chill casting and pressure die-casting. Primary casting alloys are various known aluminum and zinc alloys, but in some cases, where the size and use of the device dictates, alloys based on magnesium are suitably used.

The accuracy of precision casting not only makes further finishing unnecessary but, due to the hardness obtained by reason of the homogeneity of the cast metal, the use of thinner walls is made possible, which decreases the weight and quantity of the material used, thus further reducing costs.

Precision casting can be carried out with such accuracy that the measurement corrections of parts to be polished will be less than 0.1 mm. This polishing can be carried out by means of precision boring, precision grinding and/ or honing, but it can also be carried out by material compression, e.g. by knurling, which at the same time improves the surface of the sliding faces. Aluminum can, in this manner, be reduced to a surface roughness of 0.2 to 2 and a hardness corresponding to that of steel.

The tolerances obtained correspond easily to cylinder borings of this type, and previously were obtainable only by repeated borings and subsequent honing.

In refrigerating machines it is of decisive importance that the individual components be maintained exactly in proportion to each other and that they be kept in this position permanently. In particular, this is important in assembling of the motor support and the stator stack because of the airgap of the motor must be set very accurately.

Another object of this invention is thus to provide a construction wherein securing means, other than those heretofore used, can be utilized for assembling individual components of the compressor without introducing sup plementary working procedures. This is due to the great exactness by which the holes for such securing means for other components can be cast.

Securing is achieved either by deforming the securing means in the holes provided for them, or by deforming the surface of the holes themselves. Rivets, for exam ple, are suitable securing means because they, when located in the holes, are clenched slightly, whereby the rivets are made to bear against the inner surface of the holes, thus obtaining a locking at right angles to the axis of the rivet shaft, whereas the locking in the longitudinal direction of the rivet is taken over by the head of the rivet.

Other securing means of this type are self-tapping screws. These screws deform by an insignificant cutting of the inner surface of the hole, thus obtaining a locking in the longitudinal direction as well as crosswise.

In. this manner it is possible to obtain the same effect which previously called for a supplementary working procedure, viz. cutting threads in the holes adapted to receive securing means.

With respect to the reduction of costs, it is advantageous not only to cast the motor support integrally with the cylinder, but also to include in the casting at least one mother chamber.

In particular, this is advantageous if the cast blank contains both suction and pressure muffler chambers. Uniting of the cylinder, the mother and the motor support into one precision casting has the advantage that these components can be relatively disposed in such man her that they reinforce the motor support.

By means of precision casting, it is possible to obtain thin walls, but these thin walls would not be usable by 7 effective reinforcement to insure adequate strength.

Further objects, features and characteristics of the invention will be apparent from the following detailed description or an embodiment thereof, and from the accompanying drawings, wherein, Y

FIG. 1 is an axial sectional view of a precision cast component embodying features of the invention;

FIG. 2 is a front elevational view of the component shown;

FIG. 3 is a side elevational view of the component of FIGS. 1 and 2;

FIG. 4 is an enlarged fragmentary sectional view, as seen along the line A-A in FIG. 2, showing a cover fastened to the casting by means of a rivet; and

' FIG. 5 is a view corresponding to FIG. 4 but wherein the cover is fastened by means of a self-tapping screw.

. Referring to the drawings, and particularly to FIGS. 1 to 3, the casting illustrated defines a collar 12 formed with a bearing 1 adapted to guide the motor crank shaft of a motor compressor, and the stator of the motor is adapted to be connected with the collar 4 by securing means passing through holes 2 out through the reinforced Patented July 21, 1964.

wall 3. In addition, the cylinder 5, including the piston chamber 6, is integrally defined in the same casting, the central chamber 7 which is adapted to contain the crank is surrounded by a ring of muifierchambers 8, the axiallyopen ends of which are adapted to be closed by means of a cover 9. The holes 10 cut through the reinforced wall 11 of the collar 12 are adapted to receive securing means for the cover 9.

In addition to the securing-means holes 2 and 10 extending parallel with the bearing 1, other channels for interconnecting interior parts of the casting, or other holes for connecting means can be provided and these advantageously originate in the front face 13 of the cylinder, and are suitably located in corresponding reinforced walls 14. Thus, there are provided the holes 15 for securing means for the valve plate (not shown) and the valve cover (not shown), and the connecting channels 16 between muffier chambers 8 and the valve chamber (not shown). The recesses or

grooves

17, 18 and 19 are formed to receive valve-plate components. The collar unit illustrated is suitably cast by conventional precision-casting procedures, i.e., with extreme accuracy of form and surface. Immediately after the casting, all connecting channels, e.g. 16, and all holes for securing means, e.g., 2, 10, and 15, as well as all faces which bear against other parts, e.g. the front face of the bearing 1, of the surface 4, of the surface 12 and of the cylinder 5, are ready for use. Only the bores of bearing l and of cylinder need a smooth finishing, viz. correction of actual measurements in the amount of about 0.1 mm.

The connection between the component shown in FIGS. 1 to 3 and the adjoining parts, e.g. the cover 9, is shown in FIGS. 4 and 5, which show the fastening of cover 9, which closes the open end of the crank case chamber 7 and the open ends of the muffler chambers 8. In FIG. 4, a rivet 20 is inserted into the bore 10. During riveting, the rivet is clenched in such manner that at least part, and preferably all, of the surface of the rivet bears against the surface of bore 19. In FIG. 5, the securing means for the cover 9 is a self-tapping screw 21 which, when screwed in, cuts its own thread in the surface of the bore 10. The bore can also be a blind bore having a somewhat larger depth than the length of the screw 21. In both cases, the component is secured both axially and radially without need for carrying out a special finishing of the precision case holes.

It will be understood that the present invention is concerned with improvements in motor compressors of a known type and that many elements which serve to make up the complete motor compressor, and which form no part of the present invention, e.g. the motor, the piston, the driving connections, the capsule, the suspension system, the valves, the refrigerant conduits, and the like, have been omitted from the drawings and have not been described. A typical compresor of the type with which the invention is concerned is described, for example, in US. Patents 2,285,754 and 2,836,349.

Similarly, while reference has been made to precision casting, and while precision casting is employed in the method of this invention, this is a standard casting procedure which is described, in Casting Method Handbook Die Casting by C. 0. Herb (1958).

It is intended, therefore, that all matter contained in the foregoing description and in the drawings is to be interpreted as illustrative only and not as limitative of the invention.

The present application is related to my applications being filed on even date herewith and entitled Motor Compressor for Small Refrigerating Machines and Motor Compressor Especially for Small Refrigerating Machines, and reference is made to these co-pending applications to show how the motor and associated moving parts are combined with a casting containing the compressor cylinder and the muffler chambers.

posite to said bearing portion, a plurality of angularly spaced ribs extending longitudinally of said casting and radially outwardly of said compressor chamber defining a plurality of angularly spaced mufiler chambers disposed circumferentially of said compressor chamber, said casting comprising wall portions integrally with another tubular portion defining a cylinder for a piston, said cylinder being disposed intermediate some of said muffler chambers in a circumferential direction relative to 7 said compressor chamber in communication therewith at one end and open at an opposite end, said casting comprsing inwardly thereof portions extending inwardly thereof closing in and defining an inner end of said muffler chambers, each of said muffler chambers having an open end opposite to said inner end and opening in a common 7 direction corresponding to a direction in which said compressor chamber opens, and said collar comprising an annular collar integral with said partitions and extending generally in an axial direction of said casting.

2. A cast body component for a refrigeration compressor comprising an integral casting having, a tubular bearing portion for rotatably supporting a compressor crankshaft therein, wall portions defining another tubular portion defining a compressor chamber substantially coaxial with said annular portion in communication with said tubular bearing portion and having an open end opposite to said bearing portion, a plurality of angularly spaced ribs extending longitudinally of said casting and radially outwardly of said compressor chamber defining a plurality of angularly spaced muffier chambers disposed circumferentially of said compressor chamber, said casting comprising wall portions disposed integrally with another tubular portion defining a cylinder for a piston, said cylinder being disposed intermediate some of said mufiier chambers in a circumferential direction relative to said compressor chamber in communication therewith at one end and open at an opposite end, said casting comprising inwardly thereof portions extending inwardly thereof closing in and defining an inner end of said muffier chambers, each of said mufller chambers having an open end opposite to said inner end and opening in a common direction corresponding to a direction in which said compressor chamber opens, said collar comprising an annular collar integral with said partitions and extending generally in an axial direction of said casting, and bosses on said casting having axial holes therein for receiving fasteners for holding a plate closing said open chambers.

3. A cast body component for a refrigeration compressor comprising an integral casting having, a tubular bearing portion for rotatably supporting a compressor crankshaft therein, Wall portions defining another tubular portion defining a compressor chamber substantially coaxial with said annular portion in communication with said tubular bearing portion and having an open end opposite to said bearing portion, a plurality of angularly spaced ribs extending longitudinally of said casting and radially outwardly of said compressor chamber defining a plurality of angularly spaced muffler chambers disposed circumferentially of said compressor chamber, said cast 7 ing comprising wall portions disposed integrally with another tubular portion defining a cylinder for a piston, said cylinder being disposed intermediate some of said mufiier chambers in a circumferential direction relative to said compressor chamber in communication therewith at one end and open at an opposite end, said casting comprising inwardly thereof portions extending inwardly thereof closing in and defining an inner end of said muffler chambers, each of said muffler chambers having an open end opposite to said inner end and opening in a common direction corresponding to a direction in which said compressor chamber opens, and said collar comprising an annular collar integral with said partitions and extending generally in an axial direction of said casting, and said casting comprising a substantially flat surface circumferentially of said open end of said cylinder.

4. A cast body component for a refrigeration compressor comprising an integral casting having, a tubular bearing portion for rotatably supporting a compressor crankshaft therein, wall portions defining another tubular portion defining a compressor chamber substantially coaxial With said annular portion in communication with said tubular bearing portion and having an open end opposite to said bearing portion, a plurality of angularly spaced ribs extending longitudinally of said casting and radially outwardly of said compressor chamber defining a plurality of angularly spaced mufiler chambers disposed circurnferentially of said compressor chamber, said casting comprising wall portions disposed integrally with another tubular portion defining a cylinder for a piston,

said cylinder being disposed intermediate some of said mufiler chambers in a circumferential direction relative to said compressor chamber in communication therewith at one end and open at an opposite end, said casting comprising inwardly thereof portions extending inwardly thereof closing in and defining an inner end of said muffler chambers, each of said mufiler chambers having an open end opposite to said inner end and opening in a common direction corresponding to a direction in which said compressor chamber opens, said collar comprising an annular collar integral with said partitions and extending generally in an axial direction of said casting, and a plate closing said open chambers.

References Cited in the file of this patent UNITED STATES PATENTS 2,085,355 Greenwald June 29, 1937 2,285,754 Money June 9, 1942 2,505,709 Goldberg et al Apr. 25, 1950 2,767,903 Warner Oct. '23, 1956 2,836,349 Scheldorf May 27, 1958

Claims

1. A CAST BODY COMPONENT FOR A REFRIGERATION COMPRESSOR COMPRISING AN INTEGRAL CASTING HAVING A TUBULAR BEARING PORTION FOR ROTATABLY SUPPORTING A COMPRESSOR CRANKSHAFT THEREIN, WALL PORTIONS DEFINING ANOTHER TUBULAR PORTION DEFINING A COMPRESSOR CHAMBER SUBSTANTIALLY COAXIAL WITH SAID ANNULAR PORTION IN COMMUNICATION WITH SAID TUBULAR BEARING PORTION AND HAVING AN OPEN END OPPOSITE TO SAID BEARING PORTION, A PLURALITY OF ANGULARLY SPACED RIBS EXTENDING LONGITUDINALLY OF SAID CASTING AND RADIALLY OUTWARDLY OF SAID COMPRESSOR CHAMBER DEFINING A PLURALITY OF ANGULARLY SPACED MUFFLER CHAMBERS DISPOSED CIRCUMFERENTIALLY OF SAID COMPRESSOR CHAMBER, SAID CASTING COMPRISING WALL PORTIONS INTEGRALLY WITH ANOTHER TUBULAR PORTION DEFINING A CYLINDER FOR A PISTON, SAID CYLINDER BEING DISPOSED INTERMEDIATE SOME OF SAID MUFFLER CHAMBERS IN A CIRCUMFERENTIAL DIRECTION RELATIVE TO SAID COMPRESSOR CHAMBER IN COMMUNICATION THEREWITH AT ONE END AND OPEN AT AN OPPOSITE END, SAID CASTING COMPRISING INWARDLY THEREOF PORTIONS EXTENDING INWARDLY THEREOF CLOSING IN AND DEFINING AN INNER END OF SAID MUFFLER CHAMBERS, EACH OF SAID MUFFLER CHAMBERS HAVING AN OPEN END OPPOSITE TO SAID INNER END AND OPENING IN A COMMON DIRECTION CORRESPONDING TO A DIRECTION IN WHICH SAID COMPRESSOR CHAMBER OPENS, AND SAID COLLAR COMPRISING AN ANNULAR COLLAR INTEGRAL WITH SAID PARTITIONS AND EXTENDING GENERALLY IN AN AXIAL DIRECTION OF SAID CASTING.