Scroll type compressor

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.

BACKGROUND OF THE INVENTION 
1. Field of the invention 
This invention relates to a scroll type compressor to be employed, for 
example, in an automotive air conditioner. More particularly, the present 
invention relates to the structure of an outlet for discharging a 
compressed gas from the housing of the compressor to an external piping. 
2. Description of the Related art 
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 4a 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 4a 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 the 
rear housing. However, such a structure also increases the length of the 
compressor. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a scroll type 
compressor which can be shortened and lightened. 
In order to attain the intended object described above, a compressor 
according to the present invention has a fixed scroll disposed in a 
housing and also a movable scroll disposed to oppose to the fixed scroll 
so as to define a compression chamber between these two scrolls. As the 
movable scroll makes a circular orbital movement, the gas introduced 
through an inlet to a suction chamber is compressed in the compression 
chamber and then discharged through a discharge port into the discharge 
chamber to be exhausted through an outlet to the outside of the 
compressor. The discharge chamber is at least partly defined in the fixed 
scroll. The outlet flange protrudes from the fixed scroll outward and is 
provided with an outlet communicating to the discharge chamber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
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 axis, 
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 a 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 1atogether with a retainer 
15 by a bolt 16. 
An outlet flange 1e is formed integrally with the fixed base plate 1aon 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 1eby 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 1eis formed integrally with the 
fixed base plate 1aon 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 FIG. 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 1ein 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 1don 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 1eand 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 1eand that 
of the flange 1g may be equal. 
A fourth embodiment of the present invention will be described referring to 
FIG. 6. In this embodiment, the rear housing is omitted, and a discharge 
chamber 13 is formed within a fixed base plate 1a. An outlet flange 1eis 
formed on the outer circumference of the base plate 1aas in the first 
embodiment and is provided with an outlet 1f communicating with the 
discharge chamber 13. Furthermore, the valve 14 for opening and closing 
the discharge port 1c is omitted. 
In the fourth embodiment, since the rear housing is omitted, the entire 
axial length of the compressor can further be reduced compared with the 
first, second, and third embodiments. 
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. 7, 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. 8, an outlet flange 1eand an inlet flange 1g are 
formed on a center housing 1dat a 180 degree or 90 degree interval; 
(3) While the center housing 1dand the fixed scroll 1 are formed integrally 
in the above embodiments, the fixed scroll and the center housing may 
instead be formed separately and assembled. In this case, the center 
housing 1dmay be formed integrally with a front housing 2; and 
(4) 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. 
While the outlet and inlet are described throughout the specification as 
formed in a "flange", the term "boss" is used in the claims as more aptly 
descriptive of the structure.