US3904320A

US3904320A - Swash plate compressor

Info

Publication number: US3904320A
Application number: US358334A
Authority: US
Inventors: Atsuo Kishi; Takashi Degawa
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1972-05-10
Filing date: 1973-05-08
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09
Also published as: JPS4925505A; JPS5126168B2; CA989786A

Abstract

A swash plate compressor for use in refrigerators operating with a refrigerant gas in which is previously mixed lubricating oil, characterized in that a crank case of the compressor is so arranged as to constitute part of a low pressure passage connected to the inlet side of the compressor, and said low pressure passage is communicated with portions of the compressor which requires the supply of lubricating oil.

Description

United States Patent Kishi et al. 1 Sept. 9, 1975 1 SWASH PLATE COMPRESSOR 3,352,485 11/1967 Niki et a1 417/269 [75] inventors: Atsuo Kishi; Takashi Degawa, both 3 712,759 1973 32:? 7:269

0f Katsula. Japan 3,785,751 1 1974 Nemoto et a1.. 417/269 [73] Assign: Hitachi, Md" Japan 3,801,227 4/1974 Nakayama 417/269 1 May 1973 Primary ExaminerWil1iam L. Freeh Appl. No.: 358,334

[30] Foreign Application Priority Data May 10, 1972 Japan 47-45445 [52] U.S. Cl. 417/269 [51] Int. Cl. F041) 27/08 [58] Field of Search 417/269 [56] References Cited UNITED STATES PATENTS 2,877,653 3/1959 Masnik et a1. 74/60 3,057,545 10/1962 Ranson ct al. 417/269 Assistant ExaminerG. P. LaPointe Attorney, Agent, or FirmCraig & Antonelli 5 7 ABSTRACT A swash plate compressor for use in refrigerators operating with a refrigerant gas in which is previously mixed lubricating oil, characterized in that a crank case of the compressor is so arranged as to constitute part of a low pressure passage connected to the inlet side of the compressor, and said low pressure passage is communicated with portions of the compressor which requires the supply of lubricating oil.

16 Claims, 4 Drawing Figures PATENIEBSEP 91975 3,904,320

SHEET 1 [1F 3 FIG! PATENTEBSEP ems 3,904,320

sum 3 OF 3 SWASH PLATE COMPRESSOR BACKGROUND OF THE INVENTION This invention relates to improvements in the lubrication of a swash plate compressor for refrigerators, and more specifically to a swash plate compressor for refrigerators which is so designed that the lubrication of parts calling for lubrication is achieved by lubricating oil previously mixed in refrigerant gas, by taking advantage of the flow of said refrigerant gas without providing an oil pan or oil pump in the compressor The refrigeration cycle of a refrigerator is composed generally of a compressor, a condenser, a liquid receptacle, an expansion valve, an evaporator and a piping interconnecting these elements. In the operation, a refrigerant is compressed in the compressor, cooled and liquefied in the condenser, accumulated temperarily in the liquid receptacle, reduced in pressure during passage through the expansion valve, again gasified in the evaporator and returned to the compressor.

Swash plate compressors generally have an oil reser voir at the bottom of the crank case, and oil accumulated in said oil reservoir is supplied by a gear pump or the like to bearings, pistons and other sliding members. With such a construction, however, the oil intrudes, though in a very small amount, into the refrigeration cycle-constituting passage through gaps between the piston and cylinder wall and at other portions during the suction and compression of the refrigerant gas, and eventually the oil in the oil reservoir would be exhausted unless the oil is separated and recovered from the refrigerant. Therefore, it has been usual to separate the oil from the refrigerant in the inlet passage of the compressor and collect the separated oil in the oil reservoir.

In such arrangement, however, a high degree of vacuum pressure suddenly develops in the inlet passage at the start of the compressor, which acts in the oil reservoir through the gap between the piston and cylinder wall of the compressor or an oil recovery passage, causing boiling of the lubricating oil in said oil reservoir or the so-called oil foaming. Once the oil foaming phenomenon has occurred, the oil abruptly intrudes into the inlet passage through the aforesaid gap or oil recovery passage, with the result that the oil reservoir becomes emptied and binding of the bearings and other sliding parts results. Further, when the vacuum pressure appears in the inlet passage, the internal pressure of the oil pan also decreases, impairing substantially the performance of the gear pump and inducing the same trouble.

These problems are inevitable in the type of compressor in which oil is accumulated in a predetermined amount in an oil reservoir and supplied to the sliding parts by means of a pump or the like.

As a countermeasure, it is conceivable to make the oil reservoir large for storing a larger amount of oil therein, but increasing the size of the oil reservoir results in an increase in size of the compressor. This is undesirable for compressors intended to be used in refrig' erators, particularly in car coolers and air conditioners, which have a limited space for mounting the compres SOI'.

SUMMARY OF THE INVENTION An object of the present invention is to provide a swash plate compressor for use in refrigerators, which does not pose a lubricating oil shortage problem at the start of and under a vacuum pressure condition of the compressor.

Another object of the invention is to provide a swash plate compressor for use in refrigerators, which is so designed that the lubrication and cooling of parts required to be lubricated and cooled can be achieved without requiring an oil reservoir or oil pump.

Still another object of the invention is to provide a swash plate compressor for use in refrigerators, which is small in size, and can be manufactured at a low cost and mounted easily even in narrow spaces.

A further object of the invention is to provide a swash plate compressor for use in refrigerators, which is so arranged that the internal temperature rises uniformly, whereby the thermal deformation of the compressor is made uniform and the occurrence of an abnormal pressure is avoided which would otherwise occur due to temperature rise.

According to the invention there is provided a swash plate compressor to be used in the type of refrigerator using a refrigerant gas having lubricating oil mixed therein beforehand, characterized in that a crank case of the compressor constitutes part of a low pressure passage connected to the inlet side of the compressor and said low pressure passage is communicated with the portions in need of lubricating oil supply.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a compressor for refrigerators according to one embodiment of the invention;

FIG. 2 is a sectional view taken on the line IIII of FIG. 1;

FIG. 3 is a sectional view taken on the line llllll of FIG. 2; and

FIG. 4 is a vertical sectional view of another embodiment of the compressor for refrigerator according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The practical construction of the compressor according to the invention will be described by way of example with reference to the drawings. In FIGS. 1 to 3, reference numerals ll, 11' designate a pair of cylinder blocks disposed in a shell 19 in opposed relation, with a swash plate 12 interposed therebetween. A drive shaft 13 is rotatably supported in the cylinder blocks 11, 11 by bearings 14, 14', and the swash plate 12 is fixedly mounted on said drive shaft 13. The rotation of the drive shaft 13 is converted into a reciprocal movement of pistons 15, 15' through the swash plate, sliding members l6, l6 and steel balls l7, 17, said pistons 15, l5 respectively being slidably received in

cylinder chambers

34, 34 formed in the cylinder blocks 1 I, ll A refrigerant gas flows into a crank case 21 from an inlet pipe 18 through a low pressure passageforming inlet port 20 defined by the cylinder blocks 11, 11', and sucked into low pressure chambers 25, respec tively formed in a front cover 23 and a rear cover 24, through low

pressure passageforming openings

30, and 22, 22', respectively provided in the cylinder blocks 11, II, and thence through low pressure passage-forming outlet openings 31, 31' respectively provided in cylinder heads 29, 29'. From the low pressure chambers 25, 25', the refrigerant gas is sucked into the cylinder chambers 34, 34' through inlet openings 40 and compressed therein by the pistons l5, l5 reciprocating in said cylinder chambers. The compressed pressurized gas is discharged into high pressure chambers 26, 26' through outlet openings 41. The pressurized gas collected in the high pressure chamber 26' is discharged directly from an outlet pipe 28, while the pressurized gas collected in the high pressure chamber 26 flows into die high pressure chamber 26' through a high pressure passage-forming conduit 27 provided in the cylinder blocks 11, 11' and is discharged from the outlet pipe 28.

Lubricating oil is previously mixed in the refrigerant gas for circulation in the refrigeration cycle along therewith and, therefore, is sucked into the crank case 2] along with the refrigerant gas. in the compressor, the lubricating oil is blown directly against the swash plate 12, the sliding members l6, 16', the steel balls l7, l7 and thrust bearings 10 to lubricate them. The major portion of the lubricating oil is sucked in the form of fine particles to be attached to the entire surfaces of the sliding members, so that the quantity of lubricating oil can be very small (of the order of several c.c./hour). Relatively large particles of the lubricating oilentraining liquid are divided into smaller particles when they impinge against mainly the rotating swash plate, to suit them to movement to the sliding members and further portions in need of lubrication.

On the other hand, the lubrication of the bearings l4, l4 supporting the drive shaft 13 is effected through small channels 33, 33'. Namely, the fine particles of oil which could not separate from the refrigerant gas within the crank case 21 pass in the low pressure passage-forming

openings

30, 30 and 22, 22', and a part thereof reaches the bearings 14, 14' through the

small channels

33, 33 to lubricate the same. The remaining part of the fine particles of oil, which has not served the purpose of lubrication, are sucked into the

cylinder chambers

34, 34 and discharged into the cycle along with the compressed gas through the high pressure passage-forming conduit 27 and the outlet pipe 28 to be recycled to the inlet pipe 18.

[n this case, the amount of oil sucked at the start of the compressor is very small, unlike in the conventional compressors in which a large amount of oil is exhausted as a result of oil-foaming under the effect of high degree of vacuum pressure developed suddenly on the inlet side. Therefore, the occurrence of abnormally high pressure within the cylinders due to the non-compressibility of oil can be avoided and thereby troubles such as breakage of pipe can be eliminated.

ln should be noted in particlar that, in the compressor of the invention, the inlet pipe 18 is connected to the central portion of the shell 19 for communication with the crank case 21, and the low

pressure passageforming openings

30, 30' and 22, 22' are formed in the cylinder blocks 11, ll communicating the crank case 21 with the low pressure chambers 25, 25'. According to such construction, the flow direction of the refrigerant gas and the cross section of the flow passage change abruptly within the crank case 21, during passage of the refrigerant gas from the inlet pipe 18 through the low pressure passage-forming inlet port and

openings

30, 30' and 22, 22', providing for effective separation of the oil from the refrigerant gas. The oil thus separated goes into the clearances between the sliding members 16 and the swash plate, attaches to the surfaces of the steel balls l7, l7 and goes into the thrust bearings l0, l0 and radial bearings 14, 14' to lubricate the engaging portions thereof. Further, the engaging portions of the swash plate 12 and the sliding members 16 where heat is generated most in this type of compressor, are directly cooled by the refrigerant gas, so that the internal temperature rise of the compressor can be suppressed.

A swash plate compressor like that of the instant invention in which is employed a spray lubrication method, does not require a gear pump which is required by other types of compressor for the forced supply of oil. It should also be noted that according to the construction of the instant invention, the particles of the cold oil are distributed to every corners of the sliding parts to cool the same. This is advantageous particularly in the operation of the compressor at high speeds in that the thermal deformation of the parts becomes uniform.

In the conventional compressors, it has been necessary to provide sealing means between the journal 35 of the shaft and the low pressure chamber to minimize the lubricating oil intruding into the low pressure cmaber therefrom. in the present invention, there is no necessity for sealingly isolating the journal 35 and the low pressure chamber 25 from each other. Therefore, the

low pressure chambers

25, 25 and high pressure chambers 26, 26' can be formed in concentrical cylindrical shapes in the front cover 23 and rear cover 24. This means that the shape of the cylindrical front cover 23 and rear cover 24 can be substantially simplified, it being only necessary to form par JiIaOn walls 49 in the inside of said respective covers. 1 bus, according to the present invention, the front cover 23 and rear cover 24 can be produced by forging (these members have been produced by casting in the past), which reduces the cost of manufacture of the compressor. Also, as stated, the low pressure chambers 25, 25' and high pressure chambers 26, 26' formed in the front cover 23 and rear cover 24 can have the same shape, which is extremely advantageous in the manufacture of the compressor.

Further, in the present invention, the cylinder blocks 11, l l and the cylinder heads 29, 29' respectively also have the same shape, which enhances the exchangeability of component parts. Further, since a gear pump and an oil pan are unnecessary, the fabrication of a gear pump chamber and an oil passage bore in the drive shaft is not needed, which requires high precision. This also reduces the cost of manufacture of the compressor.

The formation of a mechanical seal chamber for accommodating the journal 35 is also unnecessary. The elimination of the mechanical seal chamber and gear pump makes it possible to increase the volumes of the low pressure chambers 25, 25' and high pressure chambers 26, 26', without increasing the outer diameter of the compressor. This is effective, in a compressor of the type having about three cylinder chambers for high and low pressure chambers, for smoothing the pulsations of incoming and outgoing refrigerant gas and thereby enhancing the cooling efficiency and reducing the noises of the refrigerator.

Swash plate compressors are frequently used in car coolers and car air conditioners. In this view, the compressor of the invention which does not require an oil pan is advantageous because it can be provided in a cylindrical shape and can be installed in the engine room having a limited space, without subjecting to a limitation in its angular position.

Another embodiment of the invention is shown in PK). 4. This embodiment is characterized by the construction of the high pressure passage 27.

Namely, the outlet pipe 28 similar to the inlet pipe 18 is provided centrally of the shell 19 and high pressure passage-forming

openings

27, 27" are formed at por tions of the cylinder blocks 11, 11 respectively. On the other hand, a noise damping chamber 43 is formed between a cover 42 fixed to the outer wall of the shell 19 and the shell 19, said noise damping chamber being in communication with the openings 27, 27' through

coil springs

50, 50.

According to such construction, it is possible to make large the cross sectional area of the

openings

27, 27 and thereby to reduce the pulsations of the discharge pressure. The pulsation suppressing effect of the openings 27, 27' is further enhanced by the effect of the noise damping chamber 43.

What is claimed is:

l. A swash plate type compressor comprising:

a casing,

a pair of cylinder blocks disposed immediately adjacent one another at a separation plane in said casmg,

a drive shaft rotatably supported by said cylinder blocks for rotation about an axis extending transverse to said separation plane,

a swash plate rotatable with said drive shaft and disposed in a crankcase formed by facing portions of said cylinder blocks, bearing means for rotatably supporting said drive shaft and swash plate being disposed in said crankcase,

cylinder bores formed in said cylinder blocks for accommodating axial sliding movement of pistons disposed therein in response to rotation of said drive shaft and swash plate,

and an inlet opening for supplying a fluid medium to said compressor for compression within said cylinder bores by said pistons,

wherein said inlet opening extends from outside said casing directly into said crankcase at said separation plane so that lubricant contained in said fluid medium is supplied directly to said bearings, said inlet opening being formed by facing portions of said cylinder blocks, said facing portions extending from immediately adjacent said casing so as to direct said fluid medium and lubricant directly radially inwardly from said casing to said crankcase and bearing means.

2. A swash plate compressor as defined in claim I, wherein the cylinder blocks each have three cylinder bores, and wherein three piston members are slidably inserted one each in said cylinder bores.

3. A swash plate compressor as defined in claim 2, wherein said cylindrical shell has a cylindrical shape over the full length thereof in the direction of the axis of rotation of the drive shaft.

4. A swash plate compressor as defined in claim 1, wherein an outlet for discharging compressed gas from said compressor is disposed at said plane separating said cylinder blocks.

5. A swash plate compressor as defined in claim 4, wherein all openings and passages of said compressor are arranged symmetrically with respect to said plane separating said cylinder blocks to effect symmetrical flow of refrigerant gas and the like through the compressor.

6. A compressor according to claim 1, wherein said bearing means and said swash plate are disposed in said crankcase at respective opposite sides of said separation plane so that lubricant is substantially symmetrically supplied to said bearings.

7. A compressor according to claim 6, wherein said cylinder blocks are symmetrical with respect to said separation plane.

8. A compressor according to claim 7, wherein an outlet for discharging all of the compressed fluid medium from said compressor is disposed at said separation plane.

9. A compressor according to claim 8, wherein all fluid medium openings and passages in said compressor are symmetrically arranged with respect to said separation plane such that flow of fluid medium through said compressor is symmetrical with resultant symmetrical thermal loadings of the compressor parts.

10. A compressor according to claim 6, wherein identical plate members with respective inlet and outlet openings are provided at respective oppositely facing outer ends of said cylinder blocks.

11. A compressor according to claim 10, wherein cover members are provided on the outer ends of said plate members which include hollow spaces serving as respective high and low pressure spaces for fluid passing through said compressor, said cover members having similar shaped hollow spaces formed therein.

12. A compressor according to claim 11, wherein said hollow spaces are formed as concentrical cylindrical spaces.

13. A compressor according to claim 12, wherein said casing exhibits an outer substantially cylindrical surface along the axial length thereof.

14. A compressor according to claim 1, wherein lubricating passages are provided which communicate low pressure passages of said compressor with lubricant using parts of said compressor that are located outside of said crankcase and inside of said casing.

15. A compressor according to claim 1, characterized in that a noise damping chamber is formed between said casing and an auxiliary cover fixed to the central portion of the outer periphery of said casing and characterized in that an outlet pipe for connecting the outlet side of the compressor with a refrigeration cycle is connected to said auxiliary cover and further an opening communicating with said noise damping chamber at one end and with a high pressure chamber of said compressor at the other end is formed in each of said cylinder blocks, thereby to form a high pressure passage.

16. A compressor according to claim 1, wherein said cylinder blocks are of similar shape such that they are interchangeable with one another.

Claims

1. A swash plate type compressor comprising: a casing, a pair of cylinder blocks disposed immediately adjacent one another at a separation plane in said casing, a drive shaft rotatably supported by said cylInder blocks for rotation about an axis extending transverse to said separation plane, a swash plate rotatable with said drive shaft and disposed in a crankcase formed by facing portions of said cylinder blocks, bearing means for rotatably supporting said drive shaft and swash plate being disposed in said crankcase, cylinder bores formed in said cylinder blocks for accommodating axial sliding movement of pistons disposed therein in response to rotation of said drive shaft and swash plate, and an inlet opening for supplying a fluid medium to said compressor for compression within said cylinder bores by said pistons, wherein said inlet opening extends from outside said casing directly into said crankcase at said separation plane so that lubricant contained in said fluid medium is supplied directly to said bearings, said inlet opening being formed by facing portions of said cylinder blocks, said facing portions extending from immediately adjacent said casing so as to direct said fluid medium and lubricant directly radially inwardly from said casing to said crankcase and bearing means.

2. A swash plate compressor as defined in claim 1, wherein the cylinder blocks each have three cylinder bores, and wherein three piston members are slidably inserted one each in said cylinder bores.