US2738122A - Compressor units for refrigerating apparatus - Google Patents

Description

March 13, 1956 L. A. J. GARDINER 2,738,122

COMPRESSOR UNITS FOR REFRIGERATING APPARATUS 2 Sheets-Sheet 1 Filed March 13, 1951 17711612107 01 510 flrzlwr 10/171 Gard/var By M Mal 'ch 13, 1956 L. A. J. GARDINER COMPRESSOR UNITS FOR REFRIGERATING APPARATUS 2 Sheets-Sheet 2 Filed March 13, 1951 COMPRESSOR UNITS FOR REFRIGERATING APPARATUS Leslie Arthur John Gardiner, Bristol, England Application March 13, 1951, Serial No. 215,225

3 Claims. (Cl. 230-58) This invention concerns improvements relating to electrically driven compressor or condensing units for refrigerating or reverse-heat-cycle apparatus, hereinafter referred to as a compressor unit of the kind set forth. An object of the invention is to provide a simple and compact unit which not only possesses the advantages of the so-called sealed unit and is inexpensive to manufacture, but also permits of servicing in the field by ordinary service engineers. j

According to the invention, a compressor unit of the kind set forth comprises a casing carrying the stator portion of the electric motor, a separate compressor housing and an intermediate bearing structure for a shaft which carries the rotor portion of the motorand the driving element of the compressor at opposite ends, the said casing and housing being releasably connected together to form a vapour-tight enclosure which can be opened by separating them.

Preferably, the bearing structure comprises a spider having a hub-like portion provided with the bearing and spiderarms releasably secured to the compressor hous- 2,738,122 Patented Mar. 13, 1956 10, 11 respectively and are connected together by a ring ing. The unit is advantageously arranged with the shaft vertical and with the motor casing above the compressor housing, the only communication between the crank-case formed in the compressor housing and the upper part of the motor casing being by way of a narrow clearance between the stator and rotor of the motor such that oil tends to be thrown down from the oil-vapour mixture rising from the said crankcase, provision being made for drawing off the vapour from the said upper casing part through a filter.

Preferred embodiments of the invention will now be more fully described by way of example and with reference to the accompanying drawings, in which- Fig. 1 is a vertical axial section through a unit with a single-cylinder compressor,

Fig. 2 a cross section, on the line II-II in Fig. 1, showing the compressor housing of the same unit with the bearing structure removed, and

Fig. 3 a similar, but more diagrammatic, view of the compressor housing of a multi-cylinder unit, one cylinder thereof being shown in section.

Referring to the unit illustrated in Figs. 1 and 2, the casing for the electric'motor comprises a pressing 1 of cylindrical shape, closed at its upper flat end 2 and open at its lower end. The stator portion of the motor, indicated generally at 3, is carried on the inside of the cylindrical wall and the stator windings 4 are connected to terminals 5 passing through insulating and vapour-tight bushings 6 in the upper wall 2. Vanes 7 for facilitating heat transfer are provided by sheet metal folded to zigzag form and arranged around the outside of the cylindrical wall 1.

The compressor housing is a casting 8 of generally cylindrical shape (as shown) or of generally polygonal shape, closed at its lower flat end 9 and open at its upper end. The open ends of the casing 1 and housing 8, whose internal diameters are-equal, have external flanges small clearance, 21 between the rotor and stator.

of studs 12, the contacting faces of the flanges being machined to ensure a tight joint.

. The bearing structure comprises an elongated hublike portion 13 with six spider arms 14 which rest upon webs 15 formed inside the casting 8 and are secured thereto by studs 16. The arms are designed to fit inside both the casing l and the housing 8 and assist in accurately locating the three said main parts in relation to another.

The rotor portion 17 of the motor is carried on the upper end 18 of a vertical shaft 19 running in a plain bearing 20 in the spider hub 13. There is a comparatively This has the elfect of throwing down the oil from the oilvapour mist which rises, between the spider arms 14,

from the crank-case space 22 in the compressor housing 8, there being no other communication between that space and the upper part23 of the casing 1. A connection 24 through which the vapour passes back from the said upper casing part 23 to the compressor system is provided with a filter 25.

In the case of the single-cylinder compressor shown in Figs. 1 and 2, one side of the wall of the housing is thickened on the inside to a chord line 26 (Fig. 2) and is bored radially to form a cylinder 27 which is extended further inwardly by a skirt 28. The outer end of the cylinder is closed by a valve plate 29 and valve cover 30 secured by studs 31 to a fiat 32 (Fig. 2) on the outside of the housing wall 8. The cover contains valve chambers 33 for suction and delivery valves 34 34 the chambers communicating with suction and delivery passages 35 carried through wing-like extensions 36 of the thickened wall part to connection pieces 40 which are pro vided with spigots 41 for the attachment of the appropriate pipe lines (not shown) and with screw-down cut-01f valves 42. This arrangement facilitates servicing by permitting of the attachment of testing instruments, the isolation of the compressor and so forth.

The compressor piston 43 is connected by a short rod 44 to the strap 45 of a driving eccentric whose sheave 46 is secured upon a threaded part 47 of the shaft 19 below the hub 13. A balancing weight 48 is carried by a plate 49 fitted over asquared part 50 of the shaft 19 above the sheave 46 so that it can be utilised to facilitate the screwing of the shaft out of the sheave when this is necessary for disassembly purposes. Below the eccentric is a thrust ball bearing 51 and below that a journal bearing 52 in a cup 53 formed on the inside of the bottom wall 9 of the housing 8. The lower part of the housing crankcase space 22 is filled withoil. A spiral groove 52' in the lowermost part of the shaft 19 acts as a pump to force oil down into the cup 53 and thence through an ing of the rod 44, so that all bearing surfaces are under forced lubrication.

In use, a unit such as has been described is effectively sealed. Nevertheless it ofiers every facility'for complete testing, maintenance, and repair on the spot by ordinary service engineers. If necessary, the unit can be completely dismantled with simple tools and parts can be replaced individually and without difiiculty. The construction of the unit is simple and it is comparatively cheap to produce, there being a minimum of expensive machining. Furthermore, the unit is readily adaptable to a variety of types and forms of plant and to plant for different purposes, either as an original component or as a replacement. A plurality of supporting lugs may be provided to permit of its mounting in a variety of ways. Finally, the construction of the unit is such that, whilst it can be employed in accordance with present general practice, it can also be used in such a manner as to enable a considerably lower temperature to be attained without encountering difficulties experienced with known units and without the necessity for using pre-cooling or secondary circuits. 1 Y

In the case of a multi-cylinder compressor, the housing 8 is formed with the necessary number ofcylinders 27, spaced around it. By Way of example, Fig. 3 illustrates a seven-cylinder compressor. Of the seven piston rods, one rod 44 'may be integral with the eccentric strap, 45, whilst the other rods 44' are connected thereto by. pivots 54 mounted between spaced flanges -55 (of which only the lower flange is seen in Fig. '-3)." Respective valve chambers 30 for the several cylinders were coupled by 'ring pipes 56 (of which one is seen in Fig. 3). Theconstruction of the unit mayotherwise be generally similar-to that of--Figs. '1 arid 2. i

1: claim:

1. A motor-compressor unit comprising a motor cas ing, a'stator of themotor carried in said casing, a -cornpressor housing, at least one compressor cylinder formed in'said-housing an'd integrally therewith, a piston slidable in the cylinder, means for'removably securing the motor casing directly to the compressor housing to form by themselves a vapor-tight enclosure, a bearing structure located within said enclosure, said bearing structure extending substantially in 'theplarie'of separation between the'm'otor casing and compressor housing to engage ad jacent areas of the 'inner surfaces of said casingand housing and being separably secured to the compressor housing, a'shaft mounted in said bearing structureto extend at one end into the motor casing and at'the other end into the compressor housing, a rotor of'the motor carried at the said one end of the shaft and driying means for the cylinder piston carried at saidother "end; of the shaft, whereby the motor casing carrying the stator is removable from the compressor housingsolely by rele asin'g the'se'curing means and the bearingstrhc ture serves to locate'the motor casing on the'c'ompre'ssor housing.

2. A motor-compressorunit according to claim 1, in which the bearing structure comprises a hub-like portion in which the shaft is mounted and a plurality of spider arms extending radially from said portion and the compressor housing is provided inwardly of its inner surfaces with as many webs as there are spider arms, said spider arms resting on said webs and being separably secured thereto.

3. A -motorcompressor unit according to claim :1 having the shaft vertical and the motor casing arranged above the compressor housing, in which unit the rotor and the stator of the motor having a narrow annular clearance therebetween which forms the only communication within the enclosure between the compressor 'housing and that part of the motor casing above the rotor and a return connection is provided between said part of the motor casing and the compressor housing externally of the enclosure, whereby oil from oil-vapor mixture rising from the compressor housing is thrown'down'and the remaining vaporis drawn off from said part of the motor casing and'returnedt'o the compressor housing by means of said connection.

References Cited in the file of this patent UNITED STATES "PATENTS 1,907,110 Hobart May 2, 1933 1 ,91;7-,7 p Geiger July 11, 1933 2,09 ,297- C ioldner et a1 Oct. 19,1937 2, 1 ;1 5,9 76 Hirche May 3, 1938 2,1 5 0, 3 47, Sorensen Mar. 14, 1939 2,153,773 Patrignaui a Apr. 11,1939, 2 -22 s,3 4 Philipp Jan. 14, 1941 2264,84? Johnson Dec. 2, 1941 --2;,3 3 1,-s7s Wentworth Oct. 19, 1943 2,628,765 Anderson Feb. 17, -3

FOREIGN PATENTS 63 3,1510 France s Feb. 1,1923

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