JPH0777188A - Scroll compressor - Google Patents

Abstract

PURPOSE:To improve the reliability of a compressor by, when a difference in pressure between a high pressure chamber and a low pressure chamber becomes larger or temperature in the high pressure chamber becomes higher during the operation of the compressor, checking the flow-in of exhaust gas fluid from the high pressure chamber to the low pressure chamber for preventing the lowering of performance, the abnormal pressure rise of the exhaust gas and the deterioration of oil. CONSTITUTION:In a scroll compressor whose casing 1 is divided into a high pressure chamber 12 and a low pressure chamber 14, an oil returning passage 7 for collecting an oil gathering in the high pressure chamber 12 into the low pressure chamber 14 is provided between the high pressure chamber 12 and the low pressure chamber 14, and the said passage 7 is provided with a differential actuating valve 8 which opens the oil returning passage 7 by its opening action when a difference in pressure between the high pressure chamber 12 and the low pressure chamber 14 is less than a fixed value and closes the passage 7 by its closing action when the difference in pressure between them is more than the fixed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a scroll compressor having an oil return passage.

[0002]

2. Description of the Related Art Generally, a scroll compressor has an oil return for returning the oil in the high pressure chamber to the low pressure chamber between the high pressure chamber and the low pressure chamber, as described in, for example, Japanese Patent Application Laid-Open No. 63-167084. It is proposed that a passage is provided. This compressor is a compressor for a refrigerator, and as shown in FIG.
A compression element D having a fixed scroll B and a movable scroll C is internally provided in the closed casing A, the compression element D is arranged in the casing A through a frame E, and at the upper side of the fixed scroll B, A partition body F is provided, a high pressure chamber I having a discharge port G and a discharge pipe H opened on the upper side of the partition body F, and a low pressure chamber having a suction pipe J opened on the lower side of the partition body F. K is provided, the motor M is installed in the low pressure chamber K, and the partition body F, the fixed scroll B, and
A communication passage L that connects the high pressure chamber I and the low pressure chamber K is formed in the frame E, a capillary tube N is inserted through the communication passage L, and the capillary tube N is inserted through the holder O into the partition body. An oil return passage P, which is held in the communication passage L in F and collects the oil accumulated in the high pressure chamber I into the low pressure chamber K, is formed by the capillary tube N.

[0003]

In the conventional scroll compressor described above, the oil accumulated in the high-pressure chamber I is caused by the differential pressure between the high-pressure chamber I and the low-pressure chamber K to cause the oil return passage P to flow.
The amount of oil returned to the low pressure chamber K through the oil return passage P varies depending on the high / low differential pressure and the viscosity of the oil in the high pressure chamber I. That is,
The flow rate Q of the fluid flowing through the oil return passage P, in other words, the capillary tube N is

[0004]

## EQU1 ## Q = (ΔPπr ² ) / (8 μl) where ΔP: high / low pressure differential pressure, r: capillary tube inner diameter μ: oil viscosity, l: capillary tube length As is clear from Equation 1, when the pressure difference (ΔP) between the high pressure chamber I and the low pressure chamber K is large, and when the temperature inside the high pressure chamber I is high and the viscosity (μ) of oil is low, the flow rate ( Q) is increased, and on the other hand, in FIG.
As indicated by the solid line 0, in the air-conditioning operation range by the operation of the compressor, in the operation region shown in FIG. 10a, that is, the operation in which the evaporation temperature is lower than the predetermined temperature and the condensation temperature is higher than the predetermined temperature. In the region, the pressure difference between the high pressure chamber K and the low pressure chamber K becomes large, the temperature of the discharged gas refrigerant also becomes high, and the viscosity (μ) of the oil of the refrigerator contained in this discharged gas refrigerant becomes low. Thus, the flow rate (Q) of the fluid flowing from the capillary tube N to the low pressure chamber K becomes large.

Moreover, in this operating range,
The circulation amount of the refrigerant is reduced, so that the amount of oil carried to the compression element D is also reduced. Therefore, in the operating region, the flow rate of the fluid flowing through the capillary tube N is small even though the amount of the refrigerating machine oil carried into the high pressure chamber I together with the discharge gas refrigerant discharged from the compression element D is small. Since it is considerably large in the calculation, not only the refrigerating machine oil but also a large amount of the discharged gas refrigerant is returned to the low pressure chamber K from the oil return passage P together with this oil. As a result, the flow of the discharged gas refrigerant into the low pressure chamber K raises the temperature in the low pressure chamber K, which causes suction overheating, which deteriorates the volumetric efficiency and deteriorates the performance. There is a problem that the temperature rises and the refrigerating machine oil deteriorates, leading to a decrease in reliability.

This phenomenon occurs even in the current refrigerant (for example, R22) currently used in the refrigerator, but it becomes more remarkable in the alternative refrigerant of R32 system, which has a large differential pressure and a high discharge gas temperature. Of.

The present invention has been made in view of the above problems, and an object thereof is to increase the differential pressure between the high pressure chamber and the low pressure chamber during operation of the compressor, or to increase the temperature of the high pressure chamber. When this happens, the oil return passage is closed to prevent the discharge gas fluid from returning from the high pressure chamber to the low pressure chamber, preventing the oil from deteriorating due to the rise in the temperature of the discharge gas fluid, and improving the reliability of the compressor. It is to provide a scroll compressor that can be improved.

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 is such that a casing 1 is internally provided with a compression element 2 having first and second scrolls 3 and 4, and this compression element 2 is provided. A high pressure chamber 12 in which the discharge port 31 and the discharge pipe 11 of the compression element 2 are opened is formed on one side, and a low pressure chamber 14 in which the suction pipe 13 is opened is formed on the other side. In the scroll compressor, which is provided with an oil return passage 7 for recovering the oil accumulated in the high pressure chamber 12 to the low pressure chamber 14 between the high pressure chamber 12 and the low pressure chamber 14, A differential pressure that opens to open the oil return passage 7 when the height differential pressure is less than or equal to a predetermined value, and closes to close the oil return passage 7 when the height differential pressure exceeds the predetermined value. The operation valve 8 is provided.

According to the second aspect of the present invention, the differential pressure operation valve 8 is slidably installed in the communication passage 81 between the high pressure chamber 12 and the low pressure chamber 14, one end of which opens to the high pressure chamber 12, A plunger 83 having an oil return passage 7 whose end opens into the low pressure chamber 14 and a spring 84 for urging the plunger 83 toward the high pressure chamber 12 are used to reduce the low pressure of the oil return passage 7 in the plunger 83. The oil return passage 7 is provided on the chamber 14 side.
Opening 72a, 72b, 7 for opening the low pressure chamber 14
A plurality of 2c are formed along the sliding direction of the plunger 83, and the openings 72a, 72b, 72c are sequentially opened and closed as the plunger 83 slides.

According to the third aspect of the present invention, a casing 1 is internally provided with a compression element 2 having first and second scrolls 3 and 4, and one side of the compression element 2 discharges the compression element 2. A high-pressure chamber 12 with an outlet 31 and a discharge pipe 11 is formed, and a low-pressure chamber 14 with an intake pipe 13 is formed on the other side, and is stored in the high-pressure chamber 12 between the high-pressure chamber 12 and the low-pressure chamber 14. In a scroll compressor provided with an oil return passage 7 for collecting oil in the low pressure chamber 14, the oil return passage 7 is opened to open the oil return passage 7 when the temperature of the high pressure chamber 12 is below a predetermined value. A thermal stress valve 9 is provided which opens the circuit and closes the oil return passage 7 when the temperature becomes higher than the predetermined value.

[0011]

According to the first aspect of the invention, since the differential pressure operating valve 8 is provided in the oil return passage 7, when the differential pressure between the high pressure chamber 12 and the low pressure chamber 14 is less than a predetermined value, the oil return passage 7 Is opened to collect the oil accumulated in the high pressure chamber 12 in the low pressure chamber 14 and prevent the oil in the low pressure chamber 14 from decreasing, while the differential pressure between the high pressure chamber 12 and the low pressure chamber 14 is a predetermined value. When it becomes larger, the oil return passage 7 can be closed to prevent the discharge gas fluid from flowing from the high pressure chamber 12 to the low pressure chamber 14. Therefore, even in the operating region where the differential pressure becomes large, the discharge gas fluid does not flow into the low pressure chamber 14, so that it is possible to avoid the intake gas from being overheated and the volumetric efficiency lowering. It is possible to prevent the temperature of the discharge gas fluid discharged to 12 from becoming abnormally high, and to prevent the deterioration of oil due to the rise in the discharge gas temperature. Therefore, regardless of the operating conditions of the compressor, the reliability of the compressor is improved. Can be improved.

According to the second aspect of the present invention, the differential pressure operation valve 8 is provided with the plunger 83 and the plunger 8
3 by a spring 84 that biases the high pressure chamber 12 side,
Low pressure chamber 1 of oil return passage 7 in the plunger 83
On the fourth side, a plurality of openings 72a, 72b, 72c that open the oil return passage 7 to the low pressure chamber 14 are formed along the sliding direction of the plunger 83, and the plunger 83
Since the opening portions 72a, 72b, 72c are sequentially opened and closed in accordance with the sliding of the differential pressure operation valve 8, the differential pressure operation valve 8 can be formed into a simple structure including the plunger 83 and the spring 84, and the height difference can be increased. In the process of pressure reaching a predetermined value,
Since the flow rate of the oil return passage 7 can be controlled according to the increase of the high and low differential pressure, the problems of performance deterioration and oil deterioration can be solved with higher accuracy.

Further, according to the third aspect of the invention, when the temperature in the high pressure chamber 12 is below a predetermined value, the oil return passage 7 is opened to collect the oil accumulated in the high pressure chamber 12 from the low pressure chamber 14. When the temperature of the high-pressure chamber 12 becomes higher than a predetermined value while the oil in the low-pressure chamber 14 is prevented from decreasing, the oil return passage 7 is closed to close the high-pressure chamber 1.
It is possible to prevent the discharge gas fluid from flowing into the low pressure chamber 14 from 2. Therefore, by merely disposing the thermal stress valve 9 which operates in response to the temperature of the high pressure chamber 12 in the oil return passage 7, the discharge gas is discharged in the operating region where the temperature in the high pressure chamber 12 becomes high. Since it can be prevented from flowing into the low pressure chamber 14, it is possible to prevent the intake gas from being overheated and the volumetric efficiency being lowered, and to prevent the temperature of the discharge gas discharged to the high pressure chamber 12 from becoming abnormally high. It is also possible to prevent the deterioration of oil due to the rise in discharge gas temperature.

[0014]

EXAMPLE A first example will be described with reference to FIGS. 1 to 5. The scroll compressor shown in FIG. 1 has a hermetic casing 1 having an oil sump at the bottom and a compression element 2 on the upper inner side and a motor M on the lower inner side of the casing 1. The compression element 2 is a fixed scroll. First scroll 3
And a second scroll 4 serving as a movable scroll. The scrolls 3 and 4 are arranged vertically opposite to each other via a frame 5, and the second scroll 4 is interlocked with the drive shaft 15 of the motor M. On the other hand, the casing 1
The partition 6 is disposed inside the first scroll 3 on the upper side thereof, the discharge port 31 of the first scroll 3 is opened on the upper side of the partition 6, and the discharge refrigerant is discharged to the outside. The discharge pipe 11 is opened into a high pressure chamber 12 and the suction pipe 13 is opened into a low pressure chamber 14, and the low pressure chamber 14 is provided with the motor M.

Therefore, the rotation of the drive shaft 15 accompanying the drive of the motor M causes the second scroll 4 to move to the first scroll.
The scroll 3 is revolved and driven, and by this revolving drive, the low-pressure gas in the low-pressure chamber 14 is sucked into the compression chamber formed by these scrolls 3 and 4, and the sucked gas is compressed and compressed. The gas is discharged from the discharge port 31 to the high pressure chamber 12, and is discharged to the outside from the discharge pipe 11.

In the scroll compressor of the first embodiment, however, the oil return passage for recovering the oil accumulated in the high pressure chamber 12 to the low pressure chamber 14 is provided between the high pressure chamber 12 and the low pressure chamber 14. 7, the oil return passage 7 is opened to open the oil return passage 7 when the pressure difference between the high pressure chamber 12 and the low pressure chamber 14 is equal to or lower than a predetermined value. The differential pressure operating valve 8 is provided which closes the oil return passage 7 when it becomes larger than a predetermined value.

That is, specifically, as shown in FIG. 1, the partition body 6, the first scroll 3, and the frame 5 are connected to each other through a communication passage 81 for communicating the high pressure chamber 12 and the low pressure chamber 14. The upper end portion of the communication passage 81 is opened to the high-pressure chamber 12 while the lower end portion is closed, and the lower portion of the communication passage 81 is formed on the side surface of the frame 5 by the low pressure. The opening portion 82 that opens to the chamber 14 is formed. A plunger 83 having an oil return passage 7 extending in the axial direction is slidably provided in the communication passage 81, and the plunger 83 is provided at the lower end of the plunger 83 toward the high pressure chamber 12 side. The biasing spring 84 is built in, and the differential pressure operating valve 8 is configured by the plunger 83 and the spring 84. Further, the oil return passage 7 formed in the plunger 83 has an upper end opening to the high pressure chamber 12, and a plurality of lower ends of the oil return passage 7 are directed toward the side surface of the plunger 83. Branch into a book and branch these branches 71a, 71b, 71
When c is opened along the sliding direction on the side surface of the plunger 83 and the plunger 83 is installed in the communication passage 81, the communication passage formed by the openings 72a, 72b, 72c in the frame 5. The open portion 82 of the opening 81 opens into the low pressure chamber 14, and each of the opening portions 72
The a, 72b, and 72c move downward from the opening portion 82 in accordance with the downward sliding of the plunger 83, so that they are sequentially closed from the lower side opening portion 72c, and all the opening portions are closed. When the portions 72a, 72b, 72c are closed, the upper opening 72a is sequentially opened as the plunger 83 slides upward.

Next, the operation of the first embodiment will be described. First, when the differential pressure between the high pressure chamber 12 and the low pressure chamber 14 is small and the differential pressure is below a predetermined value, as shown in FIG. The plunger 83 moves to the high pressure chamber 12 side by the urging force of the spring 84, and the branch passages 71a, 71b, 71c of the oil return passage 7 are connected to the open portion 8 of the communication passage 81.
The oil in the high pressure chamber 12 is recovered from the oil return passage 7 into the low pressure chamber 14, and the oil in the high pressure chamber 12 is recovered from the oil return passage 7. The amount returned is 100%.

Next, when the differential pressure becomes slightly larger than a predetermined value, as shown in FIG. 3, the plunger 83 causes the pressure in the high pressure chamber 12 to urge the spring 84 by the discharge gas. It becomes slightly larger, is pushed to the side of the low pressure chamber 14 and slides downward, and the lower side of each branch passage 71a, 71b, 71c of the oil return passage 7 is closed,
Since the amount recovered from the oil return passage 7 to the low pressure chamber 14 is reduced, the return amount from the oil return passage 7 can be set to 30 to 60%.

Further, the differential pressure is further increased,
When it becomes larger than the predetermined value, as shown in FIG.
The pressure in the high-pressure chamber 12 becomes larger and the plunger 83 becomes larger than the biasing force of the spring 84, and the plunger 83 is further pushed by the low-pressure chamber 14 side and slides downward.
All of the respective branch passages 71a, 71b, 71c of the oil return passage 7 are closed, and the low pressure chamber 1 passes through the oil return passage 7 from the oil return passage 7.
The oil cannot be recovered to 4 and the return amount from the oil return passage 7 can be set to 0%.

By the way, when the compressor of the first embodiment is applied to the refrigerating apparatus, in the operating range shown in FIG. 9, in the operating region where the differential pressure between the high pressure chamber 12 and the low pressure chamber 14 is below a predetermined value, The flow rate flowing through the oil return passage 7 is theoretically small, as is clear from the above-mentioned equation 1, and the amount of oil carried to the high-pressure chamber 12 is relatively large because the refrigerant circulation amount is large. At this time, the differential pressure operation valve 8 is opened and the oil return amount flowing through the oil return passage 7 is 100%.
Therefore, the oil accumulated in the high pressure chamber 12 is transferred to the low pressure chamber 14
Therefore, the oil in the low-pressure chamber 14 can be prevented from decreasing. Further, in an operating region where the differential pressure between the high pressure chamber 12 and the low pressure chamber 14 is larger than a predetermined value, the flow rate of the oil returning passage 7 increases and the refrigerant circulation amount decreases, so The amount of oil to be carried also decreases, but at this time, the differential pressure operation valve 8 is closed and the return amount of the oil return passage 7 can be set to 0%. Therefore, the high pressure chamber 12 to the low pressure chamber 14 It is possible to prevent the discharge gas from flowing in. Therefore, even if the differential pressure becomes large, the discharge gas does not flow into the low pressure chamber 14, so that the suction gas is overheated and the volumetric efficiency is lowered, or the temperature of the discharge gas discharged to the high pressure chamber 12 is decreased. Can be prevented from becoming abnormally high, and deterioration of oil due to a rise in discharge gas temperature can be prevented, so that the reliability of the compressor can be improved regardless of the operating conditions of the compressor.

In addition, the differential pressure operation valve 8 can have a simple structure composed of the plunger 83 and the spring 84, but in the process of reaching the predetermined value, the differential pressure operation valve 8 responds to the increase in the differential pressure. The flow rate of the oil return passage 7 can be controlled, and the problems of performance deterioration and oil deterioration can be solved with higher accuracy.

The total cross-sectional area of each of the branch passages 71a, 71b, 71c of the oil return passage 7 formed in the plunger 83 is as shown in FIG. So that all of the branch passages 71a, 71b, 71c are equal to
It is preferable that the entire amount of the oil return passage 7 is discharged to the low pressure chamber 14 when the oil return passage 7 is opened.

Incidentally, each of the branch paths 71a, 71b, 71c
In the above-mentioned embodiment, three oil tanks are formed. However, the number of oil tanks may be determined in accordance with the control of the oil return quantity. By increasing the number of oil tanks, the oil return quantity can be controlled more finely according to the operating conditions.

Next, a second embodiment will be described with reference to FIGS. The oil return passage 7 of the second embodiment shown in FIGS. 6 to 8 is connected to the partition body 6, the first scroll 3 and the frame 5 in a continuous manner and is inserted into the communication passage 81. The capillary tube 73 is fixed to the upper side of the capillary tube 73 via a seal member 74 arranged on the high pressure chamber 12 side of the communication passage 81. Then, on the opening side of the oil return passage 7 configured as described above to the high pressure chamber 12, when the temperature of the high pressure chamber 12 is a predetermined value or less, the distance from the upper end opening of the capillary tube 73 is increased. A thermal stress valve 9 is provided which opens the oil return passage 7 and sits at the upper end opening of the capillary tube 73 to close the oil return passage 7 when the temperature becomes higher than the predetermined value. The thermal stress valve 9 used in the second embodiment is composed of two metal foils having different linear expansion coefficients, and is made of a bimetal that deforms when the temperature exceeds a predetermined temperature. And as shown in FIG. 8, the opening 81a of the oil return passage 7 to the high pressure chamber 12
A step portion 92 having a diameter larger than that of the opening 81a is formed around, and a gap between the step stress 92 and the upper surface of the step portion 92 is formed on the outer circumference of the thermal stress valve 9 by a plurality of pins 93. It is fixed by setting.

Next, the operation of the second embodiment will be described. First, when the temperature of the high pressure chamber 12 is below a predetermined value, as shown in FIG. 7, the thermal stress valve 9 is horizontal without deformation. The capillary tube 7
3, the opening of the capillary tube 73 opens into the high pressure chamber 12 through the gap. Therefore, the high pressure chamber 1
The oil collected in 2 passes through the gap and passes through the seal member 74.
The oil introduced into the upper part of the oil return passage 7 flows into the capillary tube 73 and is recovered into the low pressure chamber 14. When the thermal stress valve 9 is opened, the oil is returned from the oil return passage 7. The amount can be 100%. At this time, since the thermal stress valve 9 made of bimetal is arranged above the opening of the capillary tube 73, the high pressure chamber 12 is disturbed by the discharge gas,
Even if the discharge gas is easily mixed in the oil, the discharge gas will flow into the capillary tube 73 after passing through the gap between the thermal stress valve 9 and the step portion 92. It is possible to effectively prevent the mixed oil from directly flowing into the capillary tube 73.

When the temperature of the high pressure chamber 12 becomes higher than a predetermined value, as shown in FIG. 8, the central portion of the thermal stress valve 9 is deformed so as to project downward and the capillary tube 73 of the capillary tube 73 is deformed. Since the upper end opening is closed, the flow from the capillary tube 73 to the low pressure chamber 14 is blocked, and the return amount from the oil return passage 7 can be made 0%.

As described above, in the second embodiment, the oil return passage 7 is opened and closed based on the temperature of the high pressure chamber 12, and the temperature inside the high pressure chamber 12 is increased. Is less than a predetermined value, the thermal stress valve 9
Is opened to reduce the amount of oil returned to the oil return passage 7 to 10
The oil accumulated in the high pressure chamber 12 is set to 0% and the low pressure chamber 14
It is possible to prevent the oil in the low pressure chamber 14 from decreasing, and when the temperature of the high pressure chamber 12 becomes higher than a predetermined value, the thermal stress valve 9 is closed to return the oil. The return amount of the passage 7 can be set to 0% to prevent the return of the discharge gas from the high pressure chamber 12 to the low pressure chamber 14. Therefore, only by disposing the thermal stress valve 9 that operates in response to the temperature of the high pressure chamber 12 at the opening of the oil return passage 7 on the high pressure chamber 12 side, the temperature inside the high pressure chamber 12 becomes high. At this time, the discharge gas can be prevented from flowing into the low-pressure chamber 14, and like the first embodiment,
It is possible to prevent the intake gas from overheating and prevent a decrease in volumetric efficiency, to prevent the temperature of the discharge gas discharged to the high-pressure chamber 12 from rising, and to prevent the deterioration of oil due to the rise in the discharge gas temperature.

In the second embodiment, the thermal stress valve 9 is used.
Although a bimetal is used as the above, it may be formed of a shape memory alloy.

[0030]

As described above, according to the first aspect of the invention, the oil return passage 7 is opened when the pressure difference between the high pressure chamber 12 and the low pressure chamber 14 is less than a predetermined value. Since the oil return passage 7 is opened, the differential pressure operating valve 8 that closes and closes the oil return passage 7 when the height differential pressure becomes larger than the predetermined value is provided. When the differential pressure in the low pressure chamber 14 is equal to or lower than a predetermined value, the oil return passage 7 is opened to collect the oil accumulated in the high pressure chamber 12 in the low pressure chamber 14 to reduce the oil in the low pressure chamber 14. While preventing, when the differential pressure between the high pressure chamber 12 and the low pressure chamber 14 becomes larger than a predetermined value, the oil return passage 7 is closed to prevent discharge gas from flowing from the high pressure chamber 12 to the low pressure chamber 14. It can be stopped. Therefore, even in the operating region where the differential pressure becomes large, the discharge gas fluid does not flow into the low pressure chamber 14, so that it is possible to avoid the intake gas from being overheated and the volumetric efficiency lowering. It is possible to prevent the temperature of the discharge gas fluid discharged to 12 from becoming abnormally high, and to prevent the deterioration of oil due to the rise in the discharge gas temperature. Therefore, regardless of the operating conditions of the compressor, the reliability of the compressor is improved. Can be improved.

According to the second aspect of the present invention, the differential pressure operation valve 8 is constituted by the plunger 83 and the spring 84 for urging the plunger 83 toward the high pressure chamber 12, and the plan On the side of the low pressure chamber 14 of the oil return passage 7 in the jar 83, openings 72 a, 72 b, 72 c for opening the oil return passage 7 to the low pressure chamber 14 are provided on the plunger 8.
3 are formed along the sliding direction of No. 3, and the openings 72a, 72b, 72c are formed as the plunger 83 slides.
The differential pressure operation valve 8
Although a simple structure including the plunger 83 and the spring 84 can be realized, the flow rate of the oil return passage 7 can be controlled according to the increase in the height differential pressure in the process in which the height differential pressure reaches a predetermined value. As a result, the problems of performance deterioration and oil deterioration can be solved with higher accuracy.

According to the third aspect of the present invention, when the temperature in the high pressure chamber 12 is lower than a predetermined value, the oil return passage 7 is opened so that the oil accumulated in the high pressure chamber 12 is kept at the low pressure. When the temperature of the high pressure chamber 12 becomes higher than a predetermined value while the oil in the low pressure chamber 14 is prevented from being reduced while being collected in the chamber 14, the oil return passage 7 is closed to remove the oil from the high pressure chamber 12. It is possible to prevent the discharge gas fluid from flowing into the low pressure chamber 14. Therefore, by merely disposing the thermal stress valve 9 which operates in response to the temperature of the high pressure chamber 12 in the oil return passage 7, the discharge gas is discharged in the operating region where the temperature in the high pressure chamber 12 becomes high. Since it can be prevented from flowing into the low pressure chamber 14, it is possible to prevent the intake gas from being overheated and the volumetric efficiency being lowered, and to prevent the temperature of the discharge gas discharged to the high pressure chamber 12 from becoming abnormally high.
It is also possible to prevent the deterioration of oil due to the rise in discharge gas temperature.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view showing a first embodiment of the present invention.

FIG. 2 shows a flow rate of 100 in the oil return passage in the first embodiment.
The action explanatory view when it sets to%.

FIG. 3 shows a flow rate of the oil return passage of 30 to 30 in the first embodiment.
The action explanatory view when it is set to 60%.

FIG. 4 is an operation explanatory view when the flow rate of the oil return passage in the first embodiment is set to 0%.

FIG. 5 is an operation explanatory view of the branch passage of the oil return passage in the first embodiment.

FIG. 6 is a partially cutaway sectional view showing a second embodiment of the present invention.

FIG. 7 shows a flow rate of 100 in the oil return passage in the second embodiment.
The action explanatory view when it sets to%.

FIG. 8 is an operation explanatory view when the flow rate of the oil return passage in the second embodiment is set to 0%.

FIG. 9 is an explanatory diagram showing an operating range of a refrigeration system to which the compressor of the present invention is applied.

FIG. 10 is an explanatory view showing an operating range of a refrigeration system for explaining problems caused by conventional oil return.

FIG. 11 is a sectional view of a conventional scroll compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Closed casing 2 Compression element 3 1st scroll 4 2nd scroll 31 Discharge port 11 Discharge pipe 12 High pressure chamber 13 Suction pipe 14 Low pressure chamber 7 Oil return passages 72a, 72b, 72c Opening 8 Differential pressure operation valve 81 Communication passage 83 Plan Jar 84 Spring 9 Thermal stress valve

Claims (3)

[Claims] 1. A casing (1) is internally provided with a compression element (2) having first and second scrolls (3) and (4), and the compression element (2) is provided on one side of the compression element (2). ) Discharge port (31) and discharge pipe (11) open high pressure chamber (12)
On the other side, the low pressure chamber (1
4) is formed, and oil accumulated in the high pressure chamber (12) is formed between the high pressure chamber (12) and the low pressure chamber (14).
In the scroll compressor provided with the oil return passage (7) for collecting in 4), the height difference between the high pressure chamber (12) and the low pressure chamber (14) is below a predetermined value in the oil return passage (7). The differential pressure operating valve (8) that opens to open the oil return passage (7) and closes to open the oil return passage (7) when the high and low differential pressure exceeds the predetermined value. ) Is provided, the scroll compressor. 2. A differential pressure operation valve (8) is slidably installed in a communication passage (81) between a high pressure chamber (12) and a low pressure chamber (14), and one end side is opened to the high pressure chamber (12). , A plunger (83) having an oil return passage (7) having the other end opening to the low pressure chamber (14) and a spring (84) for biasing the plunger (83) toward the high pressure chamber (12). And an opening (72a, 72b, 72c) that opens the oil return passage (7) to the low pressure chamber (14) on the low pressure chamber (14) side of the oil return passage (7) in the plunger (83). )
Are formed along the sliding direction of the plunger (83), and the openings (72a, 72b, 72c) are sequentially opened and closed as the plunger (83) slides. The scroll compressor according to claim 1. 3. A casing (1) is internally provided with a compression element (2) having first and second scrolls (3) and (4), and the compression element (2) is provided on one side of the compression element (2). ) Discharge port (31) and discharge pipe (11) open high pressure chamber (12)
On the other side, the low pressure chamber (1
4) is formed, and oil accumulated in the high pressure chamber (12) is formed between the high pressure chamber (12) and the low pressure chamber (14).
4) In a scroll compressor provided with an oil return passage (7) for recovery, the oil return passage (7) is opened when the temperature of the high pressure chamber (12) is below a predetermined value. A scroll compression valve characterized in that a thermal stress valve (9) is provided which opens (7) and closes the oil return passage (7) when the temperature becomes higher than the predetermined value. Machine.