Scroll type fluid machinery

Abstract: According to the present invention, there is provided a scroll type fluid machinery in which a pair of stationary scroll (1) and revolving scroll (2) having spiral elements set up at end plates thereof, respectively, are engaged with each other, and a high pressure fluid chamber is formed on the outside of the end plate (11) of the stationary scroll, characterized in that a low pressure fluid chamber (35) or an intermediate pressure fluid chamber is formed between the end plate of the stationary scroll and the high pressure fluid chamber. As a result, the pressure of a low pressure fluid or an intermediate pressure fluid acts on the outside of the end plate of the stationary scroll. Accordingly, there is such an effect that deformation of the end plate is prevented or reduced, and reliability of the fluid machinery may be improved.

Description: FIELD OF THE INVENTION AND RELATED ART STATEMENT The present invention relates to a scroll type fluid machinery used as a compressor, an expansion machine and the like. Fig. 3 shows an example of a conventional scroll type compressor. As shown in Fig. 3, a scroll type compression mechanism C is disposed at an upper part in a closed housing 8, and an electric motor 4 is disposed at a lower part thereof, and these are coupled interlocking with each other by means of a rotary shaft 5. The scroll type compression mechanism C is provided with a stationary scroll 1, a revolving scroll 2, a mechanism 3 for checking rotation on its axis such as an Oldham's link which allows revolution in a solar motion of the revolving scroll 2 but checks the rotation on its axis thereof, a frame 6 on which the stationary scroll 1 and the electric motor 4 are put in place, an upper bearing 71 and a lower bearing 72 which support the rotary shaft 5, and a rotating bearing 73 and a thrust bearing 74 which support the revolving scroll 2. The stationary scroll 1 consists of an end plate 11 and a spiral body 12, and a discharge port 13 and a discharge valve 17 which opens and closes the discharge port 13 are provided on the end plate 11. The revolving scroll 2 consists of an end plate 21, a spiral body 22 and a boss 23. A drive bushing 54 is supported in the boss 23 through the rotating bearing 73. Further, an eccentric pin 53 projected at the upper end of the rotary shaft 5 is supported rotatably in the drive bushing 54. Lubricating oil 81 stored at the bottom of the housing 8 is sucked up through an inlet hole 51 by means of centrifugal force generated by the rotation of the rotary shaft 5, and passes through an oil filler port 52 and lubricates the lower bearing 72, the eccentric pin 53, the upper bearing 71, the mechanism 3 for checking rotation on its axis, the rotating bearing 73, the thrust bearing 74 and the like, and is discharged to the bottom of the housing 8 through a chamber 61 and a drainage hole 62. When the electric motor 4 is driven to rotate, the rotation is transmitted to the revolving scroll 2 through a mechanism for driving revolution in a solar motion, viz., the rotary shaft 5, the eccentric pin 53, the drive bushing 54, and the rotating bearing 73, and the revolving scroll 2 revolves in a solar motion while being prevented from rotating on its axis by means of the mechanism 3 for checking rotation on its axis. Then, gas enters into the housing 8 through a suction pipe 82 and cools the electric motor 4, and thereafter, is sucked into a plurality of closed spaces 24 which are delimited by having the stationary scroll 1 and the revolving scroll 2 with each other through a suction chamber 16 from a suction passage 15 provided in the stationary scroll 1. Then, the gas reaches a central part while being compressed as the volume of the closed spaces 24 is reduced by revolution in a solar motion of the revolving scroll 2, and pushes up a discharge valve 17 from a discharge port 13 and is discharged into a first discharge cavity 14. Then, the compressed gas enters into a second discharge cavity 19 through a hole 18 which is bored on a partition wall 31, and is discharged outside therefrom through a discharge pipe 83. Besides, 84 denotes a balance weight attached to the drive bushing 54. In above-mentioned conventional scroll type compressor, high pressure gas discharged from the discharge port 13 enters into the first discharge cavity 14, and high pressure gas in this discharge cavity 14 acts on all over the outer surface of the end plate 11 of the stationary scroll 1, thereby to deform the end plate 11 to show a centrally depressed configuration by approximately several ten µm. Thus, there has been such a fear that the inner surface of the end plate 11, among others the central part thereof abuts against a tip of the spiral body 22 of the revolving scroll 2, thus generating what is called a scuffing phenomenon. JP-A-61-98987 describes a scroll compressor having a pressure chamber formed between the plate of stationary scroll and a high pressure chamber by a partition wall bolted on an annular projection of the back face of the stationary scroll plate. There is no passage by which the low pressure chamber communicates with the inside of the compressor housing. OBJECT AND SUMMARY OF THE INVENTION It is an object of the present invention which has been made in view of such a point to provide a scroll type fluid machinery in which above-described problems have been solved. In order to achieve above-mentioned object, the gist of the present invention is as follows. (I) A scroll type fluid machinery according to the preamble of claim 1 characterized in that said end plate, said both annular members and said partition wall form a low-pressure fluid chamber (35) and a passage (36) is formed in said second annular member so that said low-pressure fluid chamber may communicate with the inside of said housing into which the low pressure gas is sucked through said passage. (II) A scroll type fluid machinery characterized in that the low pressure fluid chamber is caused to communicate via said passage with a low pressure fluid atmosphere inside that housing containing a mechanism for driving said revolving scroll in a solar motion. Above-described construction being provided in above-described inventions (I) and (II), the low pressure of the low pressure fluid which is introduced into the low pressure fluid chamber acts on the outer surface of the end plate of the stationary scroll. Thus, deformation of this end plate is prevented or reduced. In this manner, it is possible to prevent what is called a scuffing phenomenon between the inner surface of the end plate of the stationary scroll and the tip of the spiral element of the revolving scroll from generating, thus improving reliability of a scroll type fluid machinery. As a result, it is possible to prevent or reduce deformation of the end plate of the stationary scroll. Accordingly, it is possible to prevent what is called a scuffing phenomenon from generating between the inner surface of the end plate of the stationary scroll and the tip of the spiral element of the revolving scroll, thereby to improve reliability of a scroll type fluid machinery. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partial longitudinal sectional view showing a first embodiment of the present invention; Fig. 2 is a partial longitudinal sectional view showing a second embodiment of the present invention; and Fig. 3 is a longitudinal sectional view of a conventional scroll type compressor. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Fig. 1 shows a first embodiment of the present invention. A cylindrical boss 30 surrounding a discharge port 13 is formed on an upper surface of an end plate 11 of a stationary scroll 1, and a tip of this boss 30 abuts against an underside of a partition wall 31 in a sealing manner. A first discharge cavity 32 is delimited by the inner circumferential surface of the boss 30, the outer surface of the end plate 11 and the inner surface of the partition wall 31, and a discharge valve 17 is disposed in the first discharge cavity 32. Further, an annular low pressure fluid chamber 35 is delimited by an inner circumferential surface of an annular flange 34 set up integrally on the periphery of the outer surface of the end plate 11, the outer circumferential surface of the cylindrical boss 30, the outer surface of the end plate 11 and the inner surface of the partition wall 31, and the low pressure fluid chamber 35 communicates with the space in the housing 8 at low pressure, viz., a low pressure fluid atmosphere through a notch 36 formed in the flange 34. Other construction is the same as that of a conventional device shown in Fig. 3, and same symbols are affixed to corresponding members. Now, the low pressure gas sucked into the housing 8 is introduced into the annular low pressure chamber 35 through the notch 36. Thus, the gas pressure acting on the outer surface of the end plate 11 of the stationary scroll 1 is reduced. Therefore, the force which presses the end plate 11 downward becomes remarkably smaller as compared with a conventional case, thus preventing or reducing downward deformation of the end plate 11. Fig. 2 shows a second embodiment of the present invention. In the embodiment shown in Fig. 2, an annular gasket 37 is placed on the upper surface of the end plate 11 of the stationary scroll 1 so as to surround the discharge port 13 and an annular gasket 38 is also placed on an outer circumferential edge of the upper surface of the end plate 11 and these gaskets 37 and 38 are adhered to the underside of the partition wall 31. Further, a discharge valve 17 is disposed in a second discharge cavity 19, and a hole 18 is opened and closed by means of this discharge valve 17. Also, a notch 40 is formed at a part of the gasket 38. In this manner, a low pressure fluid chamber 41 is delimited by the outer circumferential surface of the gasket 37, the inner circumferential surface of the gasket 38, the top surface of the end plate 11 and the underside of the partition wall 31, and the low pressure chamber 41 communicates with the space in the housing 8 at low pressure, viz., a low pressure fluid atmosphere through the notch 40. In the second embodiment, the first discharge cavity 14 no longer exists, but the area of the low pressure fluid chamber 41 may be made larger than that in the first embodiment, and the structure can also be simplified. As described above, according to the present invention, since a low pressure fluid chamber is formed between an end plate of a stationary scroll and a high pressure fluid chamber, a low pressure of a low pressure fluid introduced into the low pressure fluid chamber acts on an outer surface of an end plate of a stationary scroll. Therefore, deformation of the end plate is prevented or reduced.

Claims: A scroll type fluid machinery including a pair of stationary and revolving scrolls (1, 2) having spiral elements (12, 22) established at end plates (11, 21) of said both scrolls respectively, said both scrolls being adapted to engage each other, a high pressure fluid chamber (19) being formed at the outside of end plate of said stationary scroll and said both scrolls being disposed in a housing (8), whereby there are provided a first annular member (30) surrounding a discharge port (13) on the outer surface of said end plate (11) of said stationary scroll, a second annular member (34) on the periphery of outer surface of said end plate and a partition wall (31) is disposed to demarcate said high pressure fluid chamber (19) so that the end surfaces of said both annular members come in contact with the partition wall (31) in a sealing manner, characterized in that said end plate, said both annular members and said partition wall (31) form a low pressure fluid chamber (35) and a passage (36) is formed in said second annular member (34) so that said low-pressure fluid chamber (35) may communicate with the inside of said housing into which the low pressure far is sucked through said passage. A scroll type fluid machinery, as claimed in Claim 1, wherein said discharge port (13) is disposed in the center of said end plate (11) of said stationary scroll (1) and a cavity (32) in communication with said high-pressure fluid chamber is formed inside said first annular member (30) surrounding said discharge port (13). A scroll type fluid machinery, as claimed in Claim 1, wherein said first and second annular members are formed integrally with said end plate of said stationary scroll. A scroll type fluid machinery, as claimed in Claim 1, wherein said first and second annular members are gaskets (37, 38) interposed between said end plate of said stationary scroll and said partition wall. A scroll type fluid machinery as claimed in claim 1 characterized in that said low-pressure fluid chamber is caused to communicate via said passage (36) with a low-pressure fluid atmosphere inside said housing (8) containing a mechanism (5, 53, 54, and 73) for driving said revolving scroll in a solar motion. A scroll type fluid machinery, as claimed in Claim 5, wherein said passage is a notch disposed in said second annular member.

Inventors: HIRANO TAKAHISA, HIRANO, TAKAHISA,, Hirano, Takahisa, c/o Nagoya Tech. Inst.Mitsubishi
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1991
Main classification: F04C18
IPC codes: F04C18, F04C23