Scroll type compressor and method for producing a fixed scroll of the compressor.

Abstract: A scroll type compressor has a fixed scroll in a housing and a movable scroll opposed to the fixed scroll to define a compression chamber with the fixed scroll. Gas introduced into a suction chamber via an inlet is compressed in the compression chamber and then is discharged to a discharge chamber via a discharge port to exhaust the compressed gas from an outlet to the outside of the compressor in accordance with the circular movement of the movable scroll. A part of the discharge chamber is defined in the fixed scroll. An outlet flange protrudes from the fixed scroll. The outlet flange includes the outlet which communicates with the discharge chamber.

Description: This invention relates to a scroll type compressor to be employed, for example, in an automotive air conditioner and a method for producing a fixed scroll of such a compressor. A typical scroll type compressor is provided with a housing in which a fixed scroll is accommodated. The fixed scroll has a base plate and a spiral element. A rotary shaft is supported at the front side of the housing via a bearing, and an eccentric pin is attached to the inner end of the rotary shaft. A movable scroll having a boss at the front surface of its base plate is provided. The boss engages the eccentric pin via a bushing and a bearing so as to rotate relative to the eccentric pin. The spiral element of the movable scroll meshes with the spiral element of the fixed scroll at staggered angles. An anti-rotation mechanism is interposed between the movable scroll and a fixed pressure receiving wall of the housing. This mechanism prohibits rotation of the movable scroll and allows orbital movement thereof. Compression chambers are defined between the spiral element of the fixed scroll and that of the movable scroll. The volume of the compression chambers or pockets is reduced as they are moved from the periphery toward the center under the orbital movement of the movable scroll. Thus, a refrigerant gas is compressed in the pockets. Furthermore, in the conventional compressor described above, as shown in Fig. 9, a rear housing 42 is fixed to the rear side of a base plate 41a of a fixed scroll 41. The rear housing 42 is provided with a discharge chamber 43 for temporarily storing the high-pressure refrigerant gas discharged through a discharge port 41c of the base plate 41a so as to moderate surging of the gas. An outlet flange 42a is formed integrally with the rear housing 42 on the outer circumferential wall thereof. The outlet flange 42a has an outlet 42b for leading the gas in the discharge chamber 43 to an external refrigerant piping. In the conventional compressor, the outlet flange 42a is formed on the outer peripheral wall of the rear housing 42. Accordingly, the depth L of the rear housing 42 in the axial direction of the compressor cannot be made smaller than the diameter D of the outlet flange 42a. This undesirably lengthens the compressor. It has been proposed to form an outlet flange on the rear side wall of tile rear housing. However, such a structure also increases the length of the compressor. Furthermore, the document US 5, 173, 042 discloses another scroll type compressor of this kind. According to this state of the art, the known compressor has a fixed scroll which includes a flat end plate and an involute spiral wrap. The rear section integrally formed with the housing includes an integral exhaust cavity. An outlet port is located entirely in the plane of the cavity at a periphery of the housing. The axial dimension of the cavity must be large enough to accommodate a boss and a check valve. The outlet is, as mentioned above, located at the outer periphery of the discharge chamber and is axially offset in the rear direction from the periphery of the base plate. Therefore, this conventional compressor has also the disadvantage of an increased length in the axial direction of the scroll type compressor for reasons of the axially offset arrangement of the outlet from the base plate. It is an object of the present invention to provide a scroll type compressor which can be shortened and lightened and a method for producing a fixed scroll. In order to attain this object, a scroll type compressor according to the patent claim 1 has a fixed scroll as a center housing which has a base plate and an integral spiral element protruding therefrom and a movable scroll opposed to said fixed scroll to define a compression chamber with said fixed scroll, wherein gas introduced into a suction chamber via an inlet is compressed in said compression chamber and is then discharged via a discharge port to a discharge chamber to exhaust from an outlet communicating with said discharge chamber to the outside of the compressor in accordance with the circular movement of said movable scroll, wherein said discharge chamber having an outlet flange including said outlet is defined by said fixed scroll and a rear housing fixed to the rear surface of said base plate, wherein said outlet flange being an integral part of said fixed scroll protrudes from the outer periphery of said base plate without extending axially beyond said rear surface of said base plate. The method according to claim 7 for producing a fixed scroll of a scroll type compressor having the technical features according to claim 1, comprises the steps of: solidifying a molten metal poured into a cavity and a gate of a mold through the gate to form as an integral unit the base plate and spiral element of said fixed scroll with an outlet boss; maintaining solidified metal in the gate to form said outlet boss protruding radially from the periphery of said base plate; and drilling the outlet in said outlet boss. The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: Fig. 1 is a vertical cross-sectional view of the scroll type compressor according to a first embodiment of the invention; Fig. 2 is a partial cross-sectional view taken along the line 2-2 of Fig. 1; Fig. 3 is a cross-sectional view of the fixed scroll showing how the scroll is molded; Fig. 4 is a vertical cross-sectional view of the scroll type compressor according to a second embodiment of the invention; Fig. 5 is a partial vertical cross-sectional view of the scroll type compressor according to a third embodiment of the invention; Fig. 6 is a partial cross-sectional view of the scroll type compressor according to another embodiment of the invention; Fig. 7 is a front view of the scroll type compressor according to another embodiment of the invention; and Fig. 8 is a partial vertical cross-sectional view of a prior art scroll type compressor. A first embodiment of the present invention will now be described in detail referring to Figs. 1 to 3. As shown in Fig. 1, a fixed scroll 1 serves as a center housing 1d, and a front housing 2 is fixed to the fixed scroll 1. A rotary shaft 3 is rotatably supported via a bearing 3a in the front housing 2. An eccentric pin 4 is secured to the rotary shaft 3. A balancer weight 5 and a bushing 6 are rotatably attached to the eccentric pin 4. A movable scroll 7, which meshes with the fixed scroll 1, is rotatably supported via a radial bearing 8 by the bushing 6. These two scrolls 1, 7 are provided with base plates 1a, 7a and spiral elements 1b, 7b formed integrally with the associated base plates, respectively. The fixed base plate 1a is located at a rear part of the compressor, whereas the movable base plate 7a is located substantially at the center of the compressor. A boss 7c, in which the bushing 6 is to be fitted, is formed integrally with the movable base plate 7a at the front surface thereof. A plurality of compression chambers P are defined between the base plates 1a, 7a and the spiral elements 1b,7b. The front surface of the movable base plate 7a comprises a movable pressure receiving wall 7d. A fixed pressure receiving wall 2a is formed on the inner surface of the front housing 2. An anti-rotation mechanism K is interposed between these two pressure receiving walls 2a, 7d. This mechanism K prohibits rotation of the movable scroll 7 about its own axie, but permits orbital movement around the axis of the rotary shaft 3. To describe more specifically, the anti-rotation mechanism K has a plurality of recesses 2b (four recesses in this embodiment) formed on the fixed pressure receiving wall 2a. This mechanism K also has a plurality of recesses 7e formed on the movable base plate 7a, which are offset a predetermined distance from the recesses 2b respectively. A ring 9 is interposed between these pressure receiving walls 2a, 7d. A plurality of pins 10 are inserted into the ring 9, and the pins 10 are engaged with the inner circumferences of the recesses 2b, 7e, respectively. Furthermore, a plurality of elements 9a are formed integrally with the ring 9 on the front side and rear side thereof at a predetermined interval. These elements 9a are directed to transmit the force resulting from the pressure of the compressed refrigerant gas from the movable pressure receiving wall 7d to the fixed pressure receiving wall 2a. An inlet (not shown) is defined in the front housing 2, and a suction chamber 11 is defined between the movable scroll 7 and the inner surface of the front housing 2. A rear housing 12 is fixed to the rear surface of the fixed base plate 1a. A recess 31 is defined on the rear surface of the fixed base plate 1a. A discharge chamber 13 includes this recess 31 and an inner space 12a of the rear housing 12. A discharge port 1c is formed in the fixed base plate 1a, and a discharge valve 14 for opening and closing the discharge port 1c is provided in the discharge chamber 13. This discharge valve 14 is fixed to the base plate 1a together with a retainer 15 by a bolt 16. An outlet flange 1e is formed integrally with the fixed base plate 1a on the outer circumference thereof. The outlet flange 1e has an outlet 1f formed adjacent to the recess 31, and the outlet 1f communicates via the recess 31 to the discharge chamber 13. An external refrigerant piping 34 can be connected to the outlet flange 1e. The fixed scroll 1 is molded together with the center housing 1d by means of hot chamber type die-casting method. In die-casting the fixed scroll 1, a molten aluminum alloy is poured through a gate 22 into a cavity 23 defined between a pair of molding dies 20,21, as shown in Fig. 3. The gate 22 has an inner diameter suitable for forming the outlet flange 1e. Accordingly, the columnar section molded in the gate 22 can be utilized as the outlet flange 1e. The outlet 1f can be formed through this outlet flange 1e by drilling and the like. Next, the action of the thus constituted compressor will be described. When the eccentric pin 4 is revolved under rotation of the rotary shaft 3, the bushing 6 is allowed to make an orbital movement along a predetermined radius of circular orbit around the axis of the rotary shaft 3. Thus, the movable scroll 7 makes an orbital movement around the rotary shaft 3 while the rotation of the movable scroll 7 about its own axis is prohibited by the anti-rotation mechanism K. The plurality of pins 10 in the anti-rotation mechanism K are engaged to the fixed recesses 2b, so that rotation of the movable scroll 7 around its axis is prohibited. Furthermore, since the pins 10 are engaged with the fixed recesses 2b and the movable recesses 7e, the movable scroll 7 makes an orbital movement along a circular orbit having an orbital radius substantially represented by subtracting "r" from "R" (R-r), where "R" represents the diameter of the recesses 2b,7e and "r" represents the diameter of the pins 10. The refrigerant gas is introduced to the suction chamber 11 through the inlet (not shown) under the orbital movement of the movable scroll 7 and then allowed to flow into the compression chambers P defined between these two scrolls 1, 7. The compression chambers P converge toward the centers of the spiral elements 1b, 7b as their volumes are reduced under the orbital movement of the movable scroll 7. Thus, the refrigerant gas is compressed in the compression chambers P and discharged through the discharge port 1c into the discharge chamber 13. The refrigerant gas in the discharge chamber 13 is fed through the outlet 1f to the external refrigerant piping 34. During the compression of the refrigerant gas, the pressure of the refrigerant gas in the compression chambers P acts upon the movable scroll 7. The force resulting from this pressure is transmitted from the movable pressure receiving wall 7d via the pressure receiving elements 9a of the ring 9 to the fixed pressure receiving wall 2a. In the first embodiment, the outlet flange 1e is formed integrally with the fixed base plate 1a on the outer circumference thereof. Accordingly, the size of the rear housing 12 along the axis of the compressor can be reduced compared with the case where the outlet flange is formed on the outer circumference or rear surface of the rear housing 12. Thus, the compressor can be shortened and lightened, which is desirable given the limited engine space of an automobile. Referring to Figure 3, with regard to the first embodiment, a columnar section formed in a gate 22 for die-casting a fixed scroll 1 is utilized for forming the outlet flange 1e. Accordingly, there is no need of providing any special cavity for forming the outlet flange 1e in the dies. Next, a second embodiment of the present invention will be described referring to Fig. 4. In the second embodiment, an inlet flange 1g is formed integrally with a center housing 1d on the outer circumference thereof at a front part. An inlet 1h communicating to a suction chamber 11 is formed in the flange 1g by post-machining. Accordingly, in the second embodiment, the length of the suction flow path in the compressor and also the loss of suction gas can be reduced. There is no need of providing any inlet flange or complicated flow path in the front housing 2, thus, the shape of the front housing 2 can be simplified, reducing the number of machining steps. A third embodiment of the present invention will be described referring to Fig. 5. In this embodiment, an outlet flange 1e and an inlet flange 1g are formed adjacent to each other at different heights on the rear part of a center housing 1d. The inlet flange 1g is formed utilizing a columnar section corresponding to the gate of the mold. In this embodiment, since the flanges 1e, 1g are formed adjacent to each other, machining of the inlet and outlet can further be facilitated as compared with the second embodiment. In the third embodiment, the height of the flange 1e and that of the flange 1g may be equal. It should be understood that the present invention is not to be limited to the embodiments described above but can be embodied as follows: (1) As shown in Fig. 6, a recess 32 is formed substantially over the entire rear end surface of the fixed base plate 1a, and a discharge chamber 13 is formed by covering the recess 32 with a planar cover 33. In this structure, the shape of the rear housing can be simplified so that machining thereof can be facilitated; (2) As shown in Fig. 7, an outlet flange 1e and an inlet flange 1g are formed on a center housing 1d at a 180 degree or 90 degree interval; (3) The fixed scroll 1 may be formed by molding or by a cold chamber type die-casting method. However, in the case of using the cold chamber type die-casting method, there is a need for providing a portion for forming the flange with the molding dies 20 and 21 in place of the gate.

Claims: A scroll type compressor having a fixed scroll (1) as a center housing (1d) which has a base plate (1a) and an integral spiral element (1b) protruding therefrom and a movable scroll (7) opposed to said fixed scroll (1) to define a compression chamber (P) with said fixed scroll (1), wherein gas introduced into a suction chamber (11) via an inlet (1h) is compressed in said compression chamber (P) and is then discharged via a discharge port (1c) to a discharge chamber (13) to exhaust from an outlet (1f) communicating with said discharge chamber (13) to the outside of the compressor in accordance with the circular movement of said movable scroll (7), wherein said discharge chamber (13) having an outlet flange (1e) including said outlet (1f) is defined by said fixed scroll (1) and a rear housing (12) fixed to the rear surface of said base plate (1), wherein said outlet flange (1e) being an integral part of said fixed scroll protrudes from the outer periphery of said base plate (1a) without extending axially beyond said rear surface of said base plate (1a). A compressor according to claim 1, wherein: a part of said discharge chamber (13) includes a recess (31, 32) formed in said base plate (1a); and said rear housing (12) forms a cover member which covers said recess (31, 32) to define said discharge chamber (13). A compressor according to claim 2, wherein said cover member has an inner spacer (12a) communicating with said recess (31). A compressor according to claim 1 further comprising: an inlet flange (1g) protruding from said fixed scroll (1), wherein said inlet flange (1g) includes said inlet (1h). A compressor according to claim 4, wherein said inlet flange (1g) is disposed adjacent to said outlet flange (1e). A compressor according to claim 4, wherein said inlet flange (1g) is disposed apart from said outlet flange (1e) by a predetermined angular interval. A method for producing a fixed scroll of a scroll type compressor having the technical features according to claim 1, the method comprising the steps of: solidifying a molten metal poured into a cavity and a gate of a mold through the gate to form as an integral unit the base plate and spiral element of said fixed scroll with an outlet boss; maintaining solidified metal in the gate to form said outlet boss protruding radially from the periphery of said base plate; and drilling the outlet in said outlet boss.

Inventors: FUKANUMA TETSUHIKO, GOTO KUNIFUMI, IWANAMI SHIGEKI, TSUMAGARI YUICHI, FUKANUMA, TETSUHIKO, GOTO, KUNIFUMI, IWANAMI, SHIGEKI, TSUMAGARI, YUICHI, FUKANUMA, TETSUHIKO, C/O K.K. TOYODA, GOTO, KUNIFUMI, C/O K. K. TOYODA
Applicants: DENSO CORP, TOYODA AUTOMATIC LOOM WORKS, DENSO CORPORATION, KABUSHIKI KAISHA TOYODA JIDOSHOKKI SEISAKUSHO
Application year: 1995
Main classification: F04C18
IPC codes: F01C1, F01C21, F04C18