Scroll type fluid machine

Abstract: Object: In a scroll type fluid machine in which a stationary scroll 1 and a swivel scroll 2 engaged therewith are contained within a hermetic housing 4, a plurality of legs 15 provided on the outer circumferential edge of an end plate 11 of the stationary scroll 1 are fixed by bolts 64 to a frame 5 supporting a rotating shaft 3 via a bearing 52, a rotation prevention mechanism 6 is interposed between the frame 5 and the swivel scroll 2, and the swivel scroll 2 is connected to the rotating shaft 3 so as to make revolutional swivel motions, the diameter of the end plate 11 of the stationary scroll 1 is shortened and thereby the hermetic housing 4 is made smaller. Solving means: A cut out recess portion 25 is provided at each position, corresponding to the plurality of legs 15, of the outer circumferential portion of a circular end plate 21 of the swivel scroll 2.

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to a scroll type fluid machine to be used as a compressor or an expander. Description of the Prior Art: One example of a conventional scroll type compressor is shown in Fig. 2 and Fig. 3. In Fig. 2, numeral 4 designates a hermetic housing consisting of a cup-like right hand housing 49, a frame 5 and a cup-like left hand housing 43 and all these components are connected to one another by bolts 56. Within the right hand housing 49, an electrical motor M is disposed, and within the left hand housing 43, a scroll type compression mechanism C is disposed, respectively. The electrical motor M and the scroll type compression mechanism C are connected with each other via a rotating shaft 3. The right hand end of the rotating shaft 3 is rotatably supported by the right hand housing 49 via a sub-bearing 51 and the left hand end of the same is rotatably supported by the frame 5 via a main bearing 52. The electrical motor M consists of a rotor Ma and a stator Mb, and the rotor Ma is fixed to the rotating shaft 3 and the stator Mb is fixed to the right hand housing 49 by means of press fitting. The scroll type compression mechanism C consists of a stationary scroll 1, a swivel scroll 2, a rotation prevention mechanism 6 of an Oldham link etc. to prevent rotation of the swivel scroll 2, etc. The stationary scroll 1 comprises an end plate 11 and a spiral wrap 12 provided standingly on the inner surface of said end plate, and by the outer circumferential surface of the end plate 11 being sealingly contacted to the inner circumferential surface of the left hand housing 43. A discharge chamber 46 is formed on the left hand side of the end plate 11 and a suction chamber 47 is defined on the right hand side of same. At the center portion of the end plate 11, a discharge port 13 is holed so that this discharge port 13 is opened and closed by a discharge valve 17. The swivel scroll 2 comprises an end plate 21 and a spiral wrap 22 provided standingly on the inner surface of said end plate, and within a boss 23 provided standingly on the outer surface of the end plate 21, a drive bush 32 is fitted in rotatably via s swivel bearing 34. Within a slide groove 33 holed in the drive bush 32, an eccentric drive pin 31 provided projectingly from the left hand end of the rotating shaft 3 is fitted in slidably. The stationary scroll 1 and the swivel scroll 2 are engaged with each other with eccentricity of a predetermined distance and with deviation of angle of 180 degree, thereby a plurality of closed cavities 24 are formed. Upon the electrical motor M being driven, the swivel scroll 2 is driven via a swivel drive mechanism consisting of the rotating shaft 3, the eccentric drive pin 31, the drive bush 32, the boss 23, etc., and the swivel scroll 2, while being prevented from rotating by the rotation prevention mechanism 6, makes revolutional swivel motions on a circular track of a revolutional swivel radius. Thereupon, gas enters a low pressure chamber 48 through a suction port 44, and said gas, while it passes through a passage 58 provided around the outer circumference of the stator Mb and through a gap 59 between the stator Mb and the rotor Ma, cools the electrical motor M and then is sucked into the closed cavities 24 through a passage 54 provided in the frame 5 and through the suction chamber 47. Then, accompanying with the volumes of the closed cavities 24 being reduced by the revolutional swivel motions of the swivel scroll 2, the gas comes to the central portion while it is compressed, passes the central portion and the discharge port 13, opens forcibly the discharge valve 17 to be discharged into the discharge chamber 46 and then flows to the outside through a discharge port 45. Incidentally, numeral 18 designates a valve pressure to limit the opening of the discharge valve 17, said valve pressure being fixed together with the discharge valve 17 to the outer surface of the end plate 11 of the stationary scroll 1. Numeral 62 designates a glass terminal, and the electric power is supplied to the stator Mb of the electrical motor M via said glass terminal 62. Numeral 35 designates a balance weight fixed to the rotating shaft 3. In the conventional scroll type compressor as mentioned above, as shown in Fig. 3, the end plate 21 of the swivel scroll 2 is formed circular, and so as not to touch said end plate 21, a plurality of legs 15 (four legs in the figure) projecting to the right hand direction from the outer circumferential edge of the end plate 11 of the stationary scroll 1 are provided and said legs 15 are fixed to the frame 5 by bolts 64, thus there is a problem that the diameter of the end plate 11 of the stationary scroll 1 becomes larger and, accompanying therewith, the diameter of the hermetic housing 4 becomes also larger. A similar arrangement is also known from document EP-A-0 623 733. SUMMARY OF THE INVENTION: In order to dissolve the above-mentioned problem in the prior art, the present invention teaches a scroll type fluid machine as defined in claim 1. Specifically, this fluid machine is provided with a feature that a cut out recess portion is provided at each position, corresponding to said plurality of legs, of the outer circumferential portion of the circular end plate of the swivel scroll, wherein, when the swivel scroll makes revolutional swivel motions, said plurality of legs of the stationary scroll make relative movements within each cut out recess portion so as not to interfere with the end plate of the swivel scroll. Preferred embodiments of the fluid machine are defined in the sub-claims. BRIEF DESCRIPTION OF THE DRAWINGS: In the accompanying drawings: Fig. 1 shows a scroll type compressor of one preferred embodiment according to the present invention, wherein Fig. 1(A) is a partial longitudinal sectional view taken along line A-A of Fig. 1(B) and Fig. 1(B) is a transverse sectional view taken along line B-B of Fig. 1(A). Fig. 2 is a longitudinal sectional view of a scroll type compressor in the prior art. Fig. 3 is a transverse sectional view taken along line B-B of Fig. 2. DESCRIPTION OF THE PREFERRED EMBODIMENTS: One preferred embodiment according to the present invention is shown in Fig. 1. As shown in Fig. 1(B), a cut out recess portion 25 is formed at each position, corresponding to a plurality of legs 15 of the stationary scroll 1, of the outer circumferential portion of the circular end plate 21 of the swivel scroll 2. Said cut out recess portion 25 is of a shape having such sufficient depth d and width w that the end plate 11 of the swivel scroll 2 may not interfere with the legs 15, when the swivel scroll 2 makes revolutional swivel motions. Other constructions are same as those of the conventional one shown in Figs. 2 and 3, and corresponding components and parts are given same numerals and description is omitted. Moreover, when the swivel scroll 2 makes revolutional swivel motions, the legs 15 of the stationary scroll 1 make relative movements within each cut out recess portion 25 so as not to interfere with the end plate 21 of the swivel scroll 2. Accordingly, the fitting position of the legs 15 of the stationary scroll 1 can be moved to the centripetal direction by a length corresponding to the depth d of the cut out recess portion 25, as a result the diameter of the end plate 11 of the stationary scroll 1 can be shortened by the same length and the diameter of the hermetic housing 4 can be made smaller. According to the present invention, as a cut out recess portion is provided at each position, corresponding to the plurality of legs of the stationary scroll, of the outer circumferential portion of the circular end plate 21 of the swivel scroll, the legs of the stationary scroll does not interfere with the end plate of the swivel scroll when the swivel scroll makes revolutional swivel motions. Thus, the fitting position of the legs of the stationary scroll can be moved to the centripetal direction by a length corresponding to the depth of the cut out recess portion, as a result the diameter of the end plate of the stationary scroll can be shortened by the same length and the diameter of the hermetic housing can be made smaller. While the preferred form of the present invention has been described, variations thereto will occur to those skilled in the art within the scope of the present inventive concepts which are delineated by the following claims.

Claims: A scroll type fluid machine in which a stationary scroll (1) and a swivel scroll (2) engaged therewith are contained within a hermetic housing (4), a plurality of legs (15) provided on the outer circumferential edge of an end plate (11) of said stationary scroll (1) are fixed by bolts (64) to a frame (5) supporting a rotating shaft (3) via a bearing (52), a rotation prevention mechanism (6) is interposed between said frame (5) and said swivel scroll (2), and said swivel scroll (2) is connected to said rotating shaft (3) so as to make revolutional swivel motions, characterized in that a cut out recess portion (25) is provided at each position, corresponding to said plurality of legs (15), of the outer circumferential portion of a circular end plate (21) of said swivel scroll (2), whereby said legs (15) protrude into said cut out recess portions (25) which are of a shape having such sufficient depth (d) and width (w) that said end plate (21) of the swivel scroll (2) and said legs (15) may not interfere with each other when said swivel scroll (2) makes revolutional swivel motions. A scroll type fluid machine as claimed in claim 1, characterized in that said hermetic housing (4) is constructed by a pair of cup-like housings (43,49) each having a clamping flange on its open end side and being jointed to each other by said clamping flange, said frame (5) is provided fixedly within said hermetic housing (4) by its outer circumferential flange being interposed between said clamping flanges of the pair of cup-like housings (43,49), an electrical motor (M) is disposed at one end of said rotating shaft (3) and contained within one of said pair of cup-like housings (43,49), said stationary scroll (1) is contained within the other one of said pair of cup-like housings (43,49) and said plurality of legs (15) are disposed extendingly in the axial direction and said swivel scroll (2) is supported by said frame (5) as being a thrust bearing (53) and connected to the other end of said rotating shaft (3) so as to be driven to make the revolutional swivel motions. A scroll type fluid machine as claimed in claim 1 or 2, characterized in that a leg of said plurality of legs (15) is formed in a trapezoidal sectional shape in which the width (w) becomes narrower facing the central axis side and said recess portion (25) is formed in a trapezoidal sectional shape in which the width becomes wider facing the outer side, corresponding to said trapezoidal sectional shape of the leg (15). A scroll type fluid machine as claimed in claim 1, 2, or 3, characterized in that said plurality of legs (15) are formed at four places equally spaced on the circumference. A scroll type fluid machine as claimed in claim 1, 2, 3 or 4, characterized in that said bolts (64) are inserted from the end face, on the opposite side of said stationary scroll (1), of said frame (5), thereby said stationary scroll (1) is fastened fixedly to said frame (5).

Inventors: FUKUSHIMA MASAHIRO, ISHII MIKIHIKO, MIURA SHIGEKI, FUKUSHIMA, MASAHIRO, ISHII, MIKIHIKO, MIURA, SHIGEKI, Fukushima, Masahiro, c/o Churyo Engineering K.K., Ishii, Mikihiko, c/o Mitsubishi Jukogyo K.K., Miura, Shigeki, c/o Mitsubishi Jukogyo K.K.
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1996
Main classification: F01C1
IPC codes: F04C23, F04C18, F01C1