JPH05223073A - Capacity control mechanism of scroll type compressor - Google Patents

Abstract

PURPOSE:To prevent a piston valve from hunting caused by high pressure compressed gas flowing abruptly into a intake side chamber when the piston valve is moved in a cylinder by the reduction of control pressure introduced into a control pressure chamber. CONSTITUTION:Second communicating holes 95a, 95b are shaped to increase slightly the opening area along with the shift of the piston valve 56 at the start of opening of the holes, so that high pressure compressed gas flows gradually into an intake side chamber 81.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacity control mechanism for a scroll type compressor.

[0002]

2. Description of the Related Art One example of a conventional scroll compressor is shown in FIG.
Through FIG. In FIG. 3, reference numeral 1 denotes a closed housing, which is composed of a cup-shaped main body 2, a front end plate 4 fastened thereto by bolts 3, and a tubular member 6 fastened thereto by bolts 5. A main shaft 7 penetrating the tubular member 6 is rotatably supported by the housing 1 via bearings 8 and 9.

A fixed scroll 10 and an orbiting scroll 14 are built in the housing 1. The fixed scroll 10 comprises an end plate 11 and a spiral wrap 12 erected on the inner surface thereof, and the orbiting scroll 14 is an end plate. 15 and a spiral wrap 16 provided upright on the inner surface thereof, and the spiral wrap 15 has substantially the same shape as the spiral wrap 12 of the fixed scroll 10. Orbiting scroll 14 and fixed scroll 10
And are eccentric to each other by the revolution radius, and are engaged with each other with an angle of 180 ° as shown in the figure.

Thus, the tip seal 17 embedded in the tip surface of the spiral wrap 12 is in close contact with the inner surface of the end plate 15, and the tip seal 18 embedded in the tip surface of the spiral wrap 16 is in the end plate 11. A plurality of compression chambers 19a, 19b are formed which are in close contact with the inner surface, and the side surfaces of the spiral wraps 12 and 16 are in line contact with each other at a plurality of points and are substantially point symmetric with respect to the center of the spiral. A discharge port 29 is formed in the center of the end plate 11 of the fixed scroll 10,
Moreover, a pair of bypass ports 33a, 33b communicating with the compression chambers 19a, 19b in the middle of compression are provided.

A drive bush 21 is rotatably fitted in a cylindrical boss 20 projecting from the center of the outer surface of the end plate 15 through a bearing 23, and an eccentric hole formed in the drive bush 21. An eccentric pin 25 eccentrically provided on the inner end of the main shaft 7 is rotatably fitted in the inside of the shaft 24. A balance weight 27 is attached to the drive bush 21. Between the outer peripheral edge of the outer surface of the end plate 15 and the inner surface of the front end plate 4, a rotation preventing mechanism 40 also serving as a thrust bearing is arranged.

A capacity control block 50 is arranged outside the end plate 11 of the fixed scroll 10, and the capacity control block 50 has a cylindrical shape in which a convex portion 51 is projected on the outer surface of the end plate 11 of the fixed scroll 10. By fitting the bolt 13 into the boss 10a, passing the bolt 13 through the bolt hole 52 formed in the cup-shaped body 2 and the capacity control block 50, and screwing the tip of the bolt 13 into the fixed scroll 10, the fixed scroll 10 and It is fixed in the housing 1. The outer peripheral surface of the rear portion of the capacity control block 50 tightly and closely contacts the inner peripheral surface of the cup-shaped main body 2 to partition the inside of the housing 1 into a suction chamber 28 and a discharge cavity 31.

A discharge hole 53 communicating with the discharge port 29 is formed in the center of the capacity control block 50.
As shown in FIG. 6, the retainer 35 is provided on the outer surface of the control block 50.
It is adapted to be opened and closed by a discharge valve 30 fastened together with a bolt 36. As shown in FIG. 7, a blind hole-shaped cylinder 54 is formed on one side of the discharge hole 53, and a blind hole-shaped cavity 55 is formed on the other side in parallel with the cylinder 54.
The open ends of the cylinder 54 and the cavity 55 are suction chambers, respectively.
It communicates with 28.

A cup-shaped piston valve 56 is housed in the cylinder 54 in a sealed and slidable manner.
A control pressure chamber 80 is limited to one side of the suction side chamber 81, and a suction side chamber 81 limited to the other side communicates with the suction chamber 28. The piston valve 56 is pushed toward the inner side of the cylinder 54 by the coil spring 83 interposed between the piston valve 56 and the spring receiver 82. Then, the annular recessed groove 93 formed in the outer peripheral surface of the piston valve 56 is provided with a plurality of holes 94 through the suction side chamber.
It is in constant communication with 81.

On the other hand, a control valve 58 is provided in the cavity 55.
Is fitted and the gap between the cavity 55 and the control valve 58 is partitioned by O-rings 59, 60, 61, 62 to limit the atmospheric pressure chamber 63, the low pressure chamber 64, the control pressure chamber 65 and the high pressure chamber 66. ing. The atmospheric pressure chamber 63 communicates with the atmosphere outside the housing 1 through a through hole 67 and a pressure guiding tube (not shown).
The low pressure chamber 64 communicates with the suction chamber 28 through the through hole 68, and serves as a control pressure chamber.
As shown in FIGS. 2 and 8, 65 is a through hole 69, a concave groove 70, and a through hole.
The high pressure chamber 66 is communicated with the control pressure chamber 80 via 71, and the high pressure chamber 66 is connected to the discharge cavity via the through hole 72 as shown in FIGS.
It communicates with 31. The control valve 58 controls the high pressure HP in the discharge cavity 31 and the low pressure HP in the suction chamber 28.
It senses LP and produces a control pressure AP which is intermediate to these pressures and which can be represented as a linear function of the low pressure LP.

As shown in FIG. 8, recesses 70, 90, 91 and recesses 86, 87a, 87b, 88 are bored in the inner surface of the capacity control block 50. The seal material 85 fitted in the seal groove 84 formed in the land 57 surrounding the recesses 86, 87a, 87b, 88 is brought into close contact with the outer surface of the end plate 11 of the fixed scroll 10 to thereby form these recesses. 86 and 87a, 87b and 88 are separated from each other. The recesses 87a and 87b are separated by a partition 97. The recess 86 communicates with the control pressure chambers 65 and 80 via the groove 70 and the through holes 69 and 71. The recesses 87a, 87b communicate with the compression chambers 19a, 19b in the middle of compression through the bypass ports 33a, 33b formed in the end plate 11, respectively, and the first communication holes 89a, 89b formed in the cylinder 54. Through the suction side chamber 81. The recess 88 is a discharge hole through the recess grooves 90 and 91.
A second communication hole 92 communicating with the cylinder 53 and formed in the cylinder 54, and a concave groove 9 formed in the outer peripheral surface of the piston valve 56.
3, communicating with the suction side chamber 81 through the hole 94. The bypass ports 33a and 33b are provided at positions where the compression chambers 19a and 19b communicate with the compression chambers 19a and 19b until the compression stroke is completed and the volume is reduced to 50% during the compression stroke. ing.

When the main shaft 7 is rotated, the orbiting scroll 14 is driven by the orbiting drive mechanism including the eccentric pin 25, the drive bush 21, the boss 20, etc., and the orbiting scroll 14 is rotated by the rotation preventing mechanism 40. While being prevented, the orbital motion is performed on a circular orbit having a radius of revolution revolution, that is, an eccentric amount of the main shaft 7 and the eccentric pin 25. Then, the line contact portion between the spiral wraps 12 and 16 gradually moves toward the center of the spiral, and as a result, the compression chambers 19a and 19b move toward the center of the spiral while reducing their volumes. Along with this, the gas flowing into the suction chamber 28 through the suction port (not shown) flows from the outer end openings of the spiral wraps 12 and 16 into the compression chambers 19a.
, 19b to reach the center while being compressed and passing through the discharge port 29, the discharge valve 30 is pushed open and discharged into the discharge cavity 31, and then discharged from there through a discharge port (not shown).

When the compressor capacity is set to 0%, the control valve 58 generates a low control pressure AP. When this control pressure AP is introduced into the control pressure chamber 80 from the control pressure chamber 65 through the through hole 69, the concave groove 70, and the through hole 71, the piston valve 56 is pushed by the restoring force of the coil spring 83 and the piston valve 56 is pushed. Occupies the position shown in. Thus, since the first communication holes 89a, 89b and the second communication hole 92 are both opened, the compression chambers 19a,
Gas being compressed in 19b is bypass ports 33a, 33b,
The compressed gas that has entered the suction side chamber 81 through the recesses 87a and 87b and the first communication holes 89a and 89b, and has come to the center of the spiral,
That is, the compressed gas is discharged into the discharge port 29, the discharge hole 53, and the recess 8
8, the concave grooves 90, 91, the second communication hole 92, the concave groove 93, the hole 94 into the suction side chamber 81, these are merged in the suction side chamber 81 and discharged to the suction chamber 28, as a result, The capacity of the compressor becomes zero.

During full load operation of the compressor, that is, when its capacity is 100% at maximum, the control valve 58
Generates a high control pressure AP. Then, the high control pressure AP enters the control pressure chamber 80 and presses the inner end surface of the piston valve 56. Thus, the piston valve 56 retreats against the resilience of the coil spring 83, and its outer end occupies the position where it abuts the spring bearing 82, that is, the position shown in FIG.
In this state, the first communication holes 89a, 89b and the second communication holes 89a, 89b
Since all of 92 are closed by the piston valve 56, the compressed gas that has come to the center of the vortex passes through the discharge port 29 and the discharge hole 53, pushes the discharge valve 30 open, and opens the discharge cavity 31.
Is discharged inside.

When reducing the capacity of the compressor, a control pressure AP corresponding to the reduction rate is generated in the control valve 58. This control pressure AP passes through the control pressure chamber 80 and the piston valve
When it acts on the inner end surface of 56, the piston valve 56 stands still at a position where the pressing force by the control pressure AP and the elastic force of the coil spring 83 are in equilibrium. Therefore, when the control pressure AP decreases, only the first communication holes 89a, 89b are opened, and the compression chambers 19a, 89b
The gas in the middle of compression in 19b is discharged into the suction chamber 28 by an amount corresponding to the opening degree of the first communication holes 89a, 89b, so that the capacity of the compressor is reduced accordingly. Further, when the control pressure AP decreases and the first communication holes 89a and 89b are fully opened, the capacity of the compressor is reduced to 50%. Further, when the control pressure AP decreases, the second communication hole 92 opens, and when it fully opens, the capacity of the compressor becomes zero. In this way, the compressor capacity varies from 0% to 100%.

[0015]

In the above-mentioned conventional capacity control mechanism, when the second communication hole 92 starts to open due to the overlap with the concave groove 93 as the piston valve 56 moves, the suction side chamber 81 is not opened. The high-pressure gas after compression flows in through the second communication hole 92 and the pressure in the suction side chamber 81 rapidly changes, causing a so-called hunting phenomenon in which the stationary position of the piston valve 56 is not stable, and as a result, There was a problem that the operation of the compressor became unstable and abnormal noise was generated.

[0016]

SUMMARY OF THE INVENTION The present invention has been invented to solve the above problems, and its gist is to insert a piston valve in a cylinder in a sealed and slidable manner. Limits the control pressure chamber into which the control pressure generated by the control valve is introduced on one side of the piston valve and limits the suction side chamber communicating with the suction chamber on the other side of the piston valve, and the gas in the middle of compression to the cylinder A first communication hole that guides the compressed gas to the suction side chamber and a second communication hole that guides the compressed gas to the suction side chamber, and the piston valve moves in the cylinder as the control pressure decreases. In the capacity control mechanism of the scroll compressor for opening the first communication hole and the second communication hole in this order, the opening surface at the beginning of opening the second communication hole. There is in the capacity control mechanism of the scroll-type compressor which is characterized in that a shape slightly with the movement of the piston valve.

[0017]

In the present invention, because of the above configuration, when the piston valve moves along with the decrease in the control pressure, the opening area of the second communication hole at the beginning of opening slightly increases. Gas gradually flows into the suction side chamber. Therefore, the pressure fluctuation in the suction side chamber is reduced, and the piston valve does not hunt.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENT One embodiment of the present invention is shown in FIG. The cylinder 54 is provided with two second communication holes 95a, 95b having a smaller diameter than the conventional second communication hole 92 and having a smaller diameter. The second communication holes 95a and 95b are arranged in parallel so as to be opened simultaneously by the movement of the piston valve 56, and the opening area at the beginning of opening is slightly increased as the piston valve 56 moves. There is.
The second communication holes 95a and 95b are provided with an annular groove 93 and a plurality of holes 94 formed in the outer peripheral surface of the piston valve 56.
It is adapted to communicate with the suction side chamber 81 via. Other configurations are the same as those of the conventional one shown in FIGS.
Corresponding members are given the same reference numerals.

However, when the control pressure AP generated by the control valve 58 is low, this control pressure AP is controlled by the control pressure chamber 80.
When introduced into the piston valve 56, the coil spring
It is pushed by the restoring force of 83 and moves in the cylinder 54 to the right in FIG. 1, the first communication holes 89a and 89b are opened, and then
The second communication holes 95a and 95b are opened.

When the first communication holes 89a and 89b are opened, the compression chamber
Gas in the process of being compressed in 19a and 19b is bypass port 33a,
33b, the recesses 87a and 87b, the first communication holes 89a and 89b, and the suction side chamber 81, and then the gas is discharged into the suction chamber 28. When the second communication holes 95a, 95b are opened, the compressed high-pressure gas is discharged into the suction chamber 28 through the second communication holes 95a, 95b, the groove 93, the hole 94, and the suction side chamber 81. Therefore, when the piston valve 56 moves as the control pressure AP decreases, the second communication holes 95a, 95a
Since the opening area of b slightly increases, the compressed high pressure gas gradually flows into the suction side chamber 81. Therefore, the pressure fluctuation in the suction side chamber 81 can be suppressed, and the hunting of the piston valve 56 can be prevented.

[0021]

According to the present invention, when the piston valve moves as the control pressure decreases, the opening area of the second communication hole at the beginning of opening slightly increases, so that the high pressure gas after compression is gradually sucked. Flows into the room. Therefore, it is possible to prevent pressure fluctuations in the suction side chamber and prevent hunting of the piston valve, so that it is possible to prevent abnormal noise from occurring and to operate the compressor stably.

[Brief description of drawings]

FIG. 1 is a perspective view corresponding to FIG. 2 showing an embodiment of the present invention.

FIG. 2 is a perspective view taken along the line AA of FIG.

FIG. 3 is a vertical cross-sectional view of a conventional scroll compressor.

FIG. 4 is a view taken along the arrow B of FIG.

5 is a cross-sectional view taken along the line CC of FIG.

FIG. 6 is a view taken along the line DD of FIG.

7 is a sectional view taken along the line AA of FIG.

FIG. 8 is a view taken along the line EE of FIG.

[Explanation of symbols]

 19a, 19b Compression chamber 28 Suction chamber 29 Discharge port 33a, 33b Bypass port 54 Cylinder 56 Piston valve 58 Control valve 80 Control pressure chamber 81 Suction side chamber 89a, 89b First communication hole 95a, 95b Second communication hole

Continued Front Page (72) Inventor Takayuki Iio 3-1, Asahicho, Nishibiwajima-cho, Nishikasugai-gun, Aichi Mitsubishi Heavy Industries, Ltd. Air Conditioning Factory

Claims (1)

[Claims] 1. A piston valve is tightly slidably fitted in a cylinder to limit a control pressure chamber into which a control pressure generated by the control valve is introduced to one side of the piston valve and to limit the piston valve of the piston valve. A suction side chamber that communicates with the suction chamber is limited to the other side, and a first communication hole that guides the compressed gas to the suction side chamber and a second communication hole that guides the compressed gas to the suction side chamber are formed in the cylinder. In the displacement control mechanism of the scroll compressor, the piston valve moves in the cylinder as the control pressure decreases to open the first communication hole and the second communication hole in this order. The capacity control of the scroll compressor is characterized in that the opening area of the second communication hole at the beginning of opening is slightly increased as the piston valve moves. Mechanism.