JP6253278B2 - Refrigeration cycle - Google Patents

Description

  The present invention relates to a refrigeration cycle.

  The ozone depletion potential (ODP) of HFC32 (R32) is zero, and its global warming potential (GWP) is about 1/3 that of R410A widely used as a refrigerant in refrigeration cycles (for example, air conditioners). It is. Therefore, the refrigeration cycle using this HFC32 as a refrigerant can contribute to the reduction of environmental load.

  Conventionally, as a refrigerant compressor using HFC32, what is indicated by patent documents 1 is mentioned, for example, and the refrigerating cycle carrying this refrigerant compressor does not require a big design change, and is excellent also in efficiency.

  However, the refrigerant compressor using HFC32 has a higher discharge gas temperature than those using refrigerants such as R22, R410a, and R407c even if the compressor efficiency is the same.

  Therefore, the conventional refrigerant compressor using HFC32 has a problem that resin parts and machine oil are more likely to deteriorate than those using a refrigerant such as R22 and long-term reliability cannot be ensured.

  As a means for solving the problem of an increase in the discharge gas temperature, there is a method (hereinafter referred to as “injection”) in which an intermediate temperature refrigerant is put into a compression chamber. However, when operated under a wide range of conditions such as a room air conditioner, the injection may not be performed depending on the condition, and a valve for stopping the injection flow is required. An example of a valve that blocks this injection flow is an injection device described in Patent Document 1.

JP-A-11-107950

  The valve that cuts off the injection flow has a space that is not compressed, that is, a so-called gap volume, and causes a reduction in the efficiency of the compressor when the injection is not performed.

  Accordingly, an object of the present invention is to provide a refrigeration cycle that suppresses a decrease in compressor efficiency when injection is not performed in a refrigeration cycle that injects a low-temperature refrigerant into the compression chamber in order to lower the discharge gas temperature. is there.

The refrigeration cycle of the present invention includes a scroll flow path in which a refrigerant is circulated by sequentially connecting a scroll compressor, a condenser, a decompression device, and an evaporator, and a pipe and a scroll compressor positioned between the condenser and the decompression device. And a first injection valve that opens and closes the flow path of the injection pipe. The scroll compressor has a swirl scroll having a spiral wrap standing on the end plate, and an end plate standing on the end plate. A fixed scroll having a spiral wrap to be installed, an injection pipe connecting the fixed scroll and the injection pipe, and a second injection valve for opening and closing the flow path of the injection pipe, and the second injection valve is: A first hole formed on the wrap side of the end plate of the fixed scroll, the first hole, and the injection A second hole connecting the type, located in the second hole, a valve body for opening and closing the flow path of the injection pipe, is formed so as to protrude from the valve body, opening and closing of the second injection valve always a part regardless of having a projection portion located within the first hole.

  ADVANTAGE OF THE INVENTION According to this invention, in order to reduce discharge gas temperature, in the refrigerating cycle which injects a low-temperature refrigerant | coolant to a compression chamber, the refrigerating cycle which suppresses a compressor efficiency fall when not injecting can be provided.

It is the refrigerating cycle which concerns on 1st Embodiment. It is a longitudinal cross-sectional view of the scroll compressor which concerns on 1st Embodiment. It is an enlarged view of the injection valve of FIG. The valve body of the injection valve It is a state of the injection valve when performing the injection. The state of the injection valve when no injection is performed. It is the figure which looked at the position of the injection hole from the lap surface of the fixed scroll. It is the figure which showed the area where an injection hole opens to a compression chamber. It is the figure which showed the fall amount of the discharge gas temperature when it injects. It is the refrigerating cycle which concerns on 2nd Embodiment. It is an injection valve concerning a 3rd embodiment.

  Embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 shows a refrigeration cycle according to the first embodiment. As shown in FIG. 1, in the refrigeration cycle according to the present embodiment, a compressor 1, a condenser 18, a pressure reducing device 19 (expansion valve), and an evaporator 20 are sequentially connected in an annular shape to form a refrigerant cycle flow path. doing. The four-way valve 24 is a valve that switches between heating operation and cooling operation. The solid line in the figure is a flow path during heating operation, and the broken line is a flow path during cooling operation. In the present embodiment, the cycle configuration at the time of a solid line heating operation is shown. The injection pipe 30 is a pipe connecting the compressor 1 and the pipe between the condenser 18 and the decompression device 19. The injection pipe 30 is provided with a first injection valve 26. The injection pipe 25 c connects the injection pipe 30 and the compression chamber 11. The first injection valve 26 is an on-off valve or an expansion valve.

  FIG. 2 is a longitudinal sectional view of the scroll compressor according to the first embodiment. FIG. 3 is an enlarged view of the injection valve of FIG.

  The compressor 1 includes a compression mechanism unit 3 including a turning scroll 6 and a fixed scroll 5, an electric motor unit 4 that drives the compression mechanism unit 3, and a sealed container 2 that houses the compression mechanism unit 3 and the electric motor unit 4. . A compression mechanism unit 3 is disposed in the upper part of the sealed container 2, and an electric motor unit 4 is disposed in the lower part. Machine oil 13 (lubricating oil) is stored at the bottom of the sealed container 2.

  The sealed container 2 is configured by welding a lid chamber 2b and a bottom chamber 2c up and down to a cylindrical case 2a. The lid chamber 2b is provided with a suction pipe 2d and a discharge pipe 2e.

  The compression mechanism unit 3 includes a fixed scroll 5, a turning scroll 6, and a frame 9 that is fastened to the fixed scroll 5 with a fastener such as a bolt and supports the turning scroll 6.

  Each of the fixed scroll 5 and the orbiting scroll 6 has an end plate and a wrap, and the orbiting scroll 6 is rotatably disposed so as to face the fixed scroll 5, thereby forming a compression chamber 11.

  The outer peripheral side of the frame 9 is fixed to the inner wall surface of the sealed container 2 by welding, and includes a main bearing 9a that rotatably supports the crankshaft 7. An eccentric portion 7 b of the crankshaft 7 is connected to the lower surface side of the orbiting scroll 6.

  An Oldham ring 12 is disposed between the lower surface side of the orbiting scroll 6 and the frame 9. The Oldham ring 12 is mounted in a groove formed on the lower surface side of the orbiting scroll 6 and a groove formed on the frame 9. Yes. The Oldham ring 12 functions to revolve by receiving the eccentric rotation of the eccentric portion 7 b of the crankshaft 7 without rotating the orbiting scroll 6.

  The electric motor unit 4 includes a stator 4a and a rotor 4b. The stator 4a is fixed to the sealed container 2 by press fitting, welding, or the like. The rotor 4b is rotatably disposed in the stator 4a. A crankshaft 7 is fixed to the rotor 4b.

  The crankshaft 7 includes a main shaft 7 a and an eccentric portion 7 b and is supported by a main bearing 9 a and a lower bearing 17 provided on the frame 9. The eccentric portion 7 b is formed integrally with the main shaft 7 a of the crankshaft 7 so as to be eccentric, and is fitted to the orbiting bearing 6 a provided on the back surface of the orbiting scroll 6. The crankshaft 7 is driven by the electric motor unit 4, and the eccentric part 7 b is eccentrically rotated with respect to the main shaft 7 a so that the orbiting scroll 6 is orbited. Further, the crankshaft 7 is provided with an oil supply passage 7c that guides the machine oil 13 to the main bearing 9a, the lower bearing 17 and the slewing bearing 6a. 7d is attached.

  The gas refrigerant is guided from the suction pipe 2d to the compression chamber 11 formed by the orbiting scroll 6 and the fixed scroll 5 when the orbiting scroll 6 is orbitally moved via the crankshaft 7 driven by the electric motor unit 4. The gas refrigerant is compressed by reducing the volume as it moves in the central direction between the orbiting scroll 6 and the fixed scroll 5. The compressed gas refrigerant circulates inside the sealed container 2 of the compressor 1 and flows out through the discharge pipe 2e.

  When the temperature of the discharge gas flowing out to the outside is high, the temperature of the entire compressor 1 is increased, and the reliability of sliding of the resin material and the bearing used in the electric motor is remarkably lowered. For example, when R32 is used as a refrigerant in a room air conditioner, the discharge gas temperature rises by about 30 ° C. at the maximum with respect to R410A. As a means for lowering the discharge gas temperature, there is a method of injecting a low-temperature refrigerant into the compression chamber 11. Currently, widely used air conditioners are operated throughout the year, so the operating conditions of the compressors are wide-range. In the case of R32, under the high load condition, the temperature exceeds the heat resistance temperature of the resin material of the electric motor. Therefore, it is necessary to perform injection to make the discharge gas temperature below the heat resistance temperature of the resin material. On the other hand, under conditions with a small load, the discharge gas temperature does not rise to the heat resistance temperature of the resin material, and the discharge gas temperature can be made equal to or lower than the heat resistance temperature of the resin material without performing injection. By performing the injection, the discharge gas temperature can be lowered, but the heating capacity is lowered. In other words, it is desirable not to perform injection in order to maintain the heating capacity under conditions where it is not necessary to lower the discharge gas temperature during heating operation.

  In order to make these two events compatible, a valve that cuts off the injection becomes necessary. The scroll compressor of the present embodiment is provided with a first injection valve 26 that shuts off this injection.

  However, the first injection valve 26 for blocking the injection is installed outside the compressor 1, and the injection pipe 30 and the injection pipe 25 c between the first injection valve 26 and the compression chamber 11 of the compressor 1 are provided. It remains in communication with the compression chamber 11. Therefore, in the present embodiment, the compressor 1 includes the second injection valve 25.

  Hereinafter, the second injection valve 25 will be described with reference to FIG. A first hole 25 a is formed in the tooth bottom (end plate) 5 a of the fixed scroll 5. The first hole 25a communicates with the second hole 25b, and an injection pipe 25c is attached to the fixed scroll 5 by press fitting or the like above the second hole 25b. The valve body 25d of the valve body is accommodated in the second hole 25b, and when the injection is not performed, the injection is blocked by the valve body 25d.

  FIG. 4 shows a valve body of the injection valve. The valve body is formed with a valve body 25 and a protrusion 25e, and the protrusion 25e is inserted into the first hole 25a. An injection passage 25f is provided at the outer periphery of the valve main body 25d and the root of the valve main body 25d, and serves as a refrigerant passage at the time of injection.

  Next, the operation of the second injection valve 25 will be described with reference to FIGS. FIG. 5 shows the state of the injection valve during injection. FIG. 6 shows the state of the injection valve when injection is not performed.

  As shown in FIG. 2, the injection pipe 25 c communicates with a high-pressure and medium-temperature refrigerant through the first injection valve 26. For example, a general refrigeration cycle is a refrigerant after being condensed in a condenser. When the first injection valve 26 is opened, a high-pressure and medium-temperature refrigerant flows into the second injection valve 25 through the injection pipe 25c. When the refrigerant flows in, the valve body 25d is pushed down as shown in FIG. 5, and flows into the compression chamber 11 through the injection passage 25f in the first hole 25a and the second hole 25b. When the medium temperature refrigerant flows, the temperature of the refrigerant in the compression chamber 11 decreases, and as a result, the discharge gas temperature decreases.

  When the first injection valve 26 is closed, the pressure in the injection pipe 25c decreases, and the valve body 25d is pushed up by the pressure in the compression chamber 11 as shown in FIG. When the valve body 25d is pushed up, the upper surface of the valve body 25d comes into contact with the injection pipe 25c and shuts off the injection pipe 25c and the compression chamber 11.

  When this injection is cut off, the space of the first hole 25a and the second hole 25b becomes a gap volume that is not compressed. The gap volume communicates with the compression chamber 11, and the refrigerant existing in the gap volume rises to the same pressure as the compression chamber 11. However, the high-pressure refrigerant existing in the gap volume is not discharged as discharge gas but flows into the compression chamber 11 to be formed next. That is, the increase in invalid power causes a reduction in compressor efficiency. On the other hand, it is conceivable to reduce the gap volume by shortening the first hole 25a, but there is a limit to shortening the first hole 25a in order to maintain the strength.

  Therefore, in the present embodiment, the protrusion 25e formed on the valve body is inserted into the first hole 25a to reduce the gap volume. That is, in the refrigeration cycle of the present embodiment, the second injection valve 25 connects the first hole 25a formed on the wrap side of the end plate of the fixed scroll 5, the first hole 25a, and the injection pipe 25c. It has the 2nd hole 25b, the valve main body 25d which is located in the 2nd hole 25b, and opens and closes the flow path of the injection pipe 25c, and the projection part 25e located in the 1st hole 25a at least. According to this embodiment, it is possible to reduce the range of reduction in compressor efficiency due to an increase in invalid power.

  The first hole 25a, the second hole 25b, the valve body 25d, and the protrusion 25e according to the present embodiment are cylindrical, and the diameter of the second hole 25b is larger than the diameter of the first hole 25a, and The diameter of the valve body 25d is larger than the diameter of the protrusion 25e. According to such a shape, the gap volume can be further reduced.

  In the second injection valve 25, the protrusion 25e is inserted into the first hole 25a even when the valve body 25d is in contact with the injection pipe 25c. Each of the valve body 25d and the protrusion 25e has an injection passage 25f (groove), and the refrigerant flowing from the injection pipe 25c into the second hole 25b and the first hole 25a flows into the compression chamber 11 through the injection passage 25f. To do. In other words, the flow path between the valve body 25d and the second hole 25b and the flow path between the protrusion 25e and the first hole 25a are formed by the injection passage 25f (groove).

  Next, the operation of injection will be described. When the outside air temperature is low and the room temperature is low, for example, when the air conditioner is started, in order to warm the room temperature quickly, the rotation speed of the compressor 1 is increased and the decompression device 19 is throttled to discharge pressure and discharge Increase gas temperature. When the temperature becomes equal to or higher than the temperature Tmax that can ensure the reliability of the resin material of the electric motor 4, the first injection valve 26 is opened, through the injection pipe 30, the injection pipe 25c, the second hole 25b, and the first hole 25a, High pressure and low temperature refrigerant is injected into the compression chamber 11 to lower the discharge gas temperature. Thereafter, when the room temperature rises and the discharge pressure decreases and the discharge gas temperature falls below Tmax, the first injection valve 26 and the second injection valve 25 are closed to block the flow of low-temperature refrigerant into the compression chamber 11. To do. At this time, since the scroll compressor has a small gap volume between the first hole 25a and the second hole 25b, it is possible to prevent a reduction in compressor efficiency.

  FIG. 7 is a view of the position of the injection hole as seen from the wrap surface of the fixed scroll. FIG. 7 shows the position of the first hole 25a when the fixed scroll 5 is viewed from the compression chamber 11 side. The first hole 25a is formed in the center of the width of the tooth bottom portion 5a of the fixed scroll 5, and opens to both the turning outer line chamber 11a and the turning extension room 11b by the turning motion of the turning scroll 6. Here, the diameter of the first hole 25a is smaller than the tooth thickness of the orbiting scroll 5, and the orbiting outer line chamber 11a and the orbiting inner line chamber 11b do not communicate with each other via the first hole 25a. Yes.

  FIG. 8 is a view showing a section where the injection hole opens into the compression chamber. FIG. 8 shows an opening section of the first hole 25a shown in FIG. Here, the vertical axis is pressure, and the horizontal axis is the rotation angle of the crankshaft.

  Since the scroll wrap shown in the present embodiment has an asymmetric tooth profile, the start of compression of the swivel extension chamber 11b is delayed by 180 deg with respect to the swirl extension chamber 11a. The broken lines indicate the opening sections of the first holes 25a to the respective compression chambers 11, but none of them opens to the suction pressure chamber (suction chamber 10), and opens to the compression chamber 11 after the suction is completed. To do.

  FIG. 9 is a diagram showing a decrease amount of the discharge gas temperature when the injection is performed. FIG. 9 shows the discharge gas temperature when R32 is used as the refrigerant and injected into the compression chamber 11 in the opening section shown in FIG. The vertical axis indicates the discharge gas temperature without injection of R410A as 100%. As conditions, it is assumed that the room air conditioner has an outside temperature of −15 ° C. and a heating capacity of 8 kW.

  FIG. 9 shows two cases, when the gas is injected and when the liquid is injected. However, even if the amount of the gas is increased, the discharge gas temperature does not decrease to R410A. Conversely, the liquid has a large cooling effect and is equivalent to the discharge gas temperature of R410A with a small amount of injection. If liquid injection flows into the compression chamber 11 excessively, the discharge gas temperature will drop too much, leading to a reduction in heating capacity. Therefore, in order to keep the reliability equivalent to R410A, the discharge gas temperature is preferably about the same as R410A. However, the injection amount at which the discharge gas temperature becomes equivalent to R410A is very small. To control this injection amount, it is necessary to increase the passage resistance of the injection valve. In order to increase the passage resistance, there is a method of reducing the diameter of the first hole 25a. However, according to the author's study, in order to make the injection amount equal to the discharge gas temperature of R410A, the first hole 25a It has been found that the diameter needs to be 1 mm or less. Machining holes of 1 mm or less has problems such as thin drills and broken drills, and is not suitable for mass-produced products such as compressors for room air conditioners.

  In response to such a problem, the second injection valve 25 of the present embodiment has a structure in which the protrusion 25e of the valve body is inserted into the first hole 25a, and in order to increase the passage resistance, the protrusion What is necessary is just to design small with the clearance gap between 25e and the 1st hole 25a. For example, if the diameter of the protrusion 25e is 3 mm, finishing with a diameter gap of about 0.05 mm according to the current processing technology is processing accuracy that can be established as a sufficiently mass-produced product.

  As described above, the scroll compressor according to the first embodiment injects a low-temperature refrigerant into the compression chamber 11 in order to lower the discharge gas temperature, but the second injection valve 25 when the injection is shut off. Since the gap volume can be reduced as much as possible, a reduction in compressor efficiency can be prevented. Furthermore, when liquid refrigerant is injected, excessive injection can be prevented by reducing the gap between the first hole 25a and the protrusion 25e.

  In addition, although this embodiment demonstrated the case where the injection piping 30 was used as the piping which connects the piping between the condenser 18 and the decompression device 19, and the compressor 1, further between the condenser 18 and the decompression device 19 was demonstrated. A pressure reducing device may be provided, and the injection pipe 30 may be configured as a pipe that connects the pipe between the two pressure reducing apparatuses and the compressor 1.

  Moreover, although this embodiment demonstrated the case where HFC32 was used as a refrigerant | coolant, discharge gas temperature becomes high temperature and it can apply also to the other refrigerant | coolant which becomes easy to deteriorate resin components and machine oil.

  Next, a second embodiment will be described. FIG. 10 shows a refrigeration cycle according to the second embodiment. In addition, in this embodiment, the same code | symbol is attached | subjected about the component similar to 1st Embodiment, and the detailed description is abbreviate | omitted.

  The difference from the first embodiment is that a gas-liquid separator 21 is installed between the condenser 18 and the decompression device 19, and a pre-stage decompression device 19 a is provided upstream of the gas-liquid separator 21.

  The gas-liquid separator 21 is provided with a pipe for flowing a gas into the injection pipe 25c in addition to a pipe for flowing the liquid into the injection pipe 25c.

  Under a high load condition where the discharge gas temperature exceeds the heat resistance temperature of the resin material of the motor, liquid injection is performed and the discharge gas temperature of the compressor 1 is controlled to be equal to or lower than the heat resistance temperature of the resin material of the motor. On the other hand, gas injection is performed under a low load condition where the discharge gas temperature does not rise so much. Since gas injection can reduce the pressure loss of the refrigerant in the evaporator, according to the present embodiment, the compression power of the compressor 1 can be reduced.

  Next, a third embodiment will be described. FIG. 11 shows an injection valve according to the third embodiment. In addition, in this embodiment, the same code | symbol is attached | subjected about the component similar to 1st Embodiment, and the detailed description is abbreviate | omitted.

  In the third injection valve 27 of the present embodiment, a third hole 27a formed in the fixed scroll 5 has a truncated cone shape, and a hemispherical valve body 27d is accommodated in the third hole 27a. ing. An injection passage 27f is provided on the spherical surface of the valve body 27d, and serves as a refrigerant passage at the time of injection. By adopting this configuration, it is possible to reduce the gap volume when injection is not performed, and to suppress a reduction in compressor efficiency.

  Note that the truncated cone having the shape of the third hole 27a includes a shape composed of a truncated cone and a rectangular parallelepiped as shown in FIG. Further, the hemispherical shape of the valve body 27d includes a semi-ellipsoidal shape and the like.

DESCRIPTION OF SYMBOLS 1 Scroll compressor 2 Airtight container 2a Case 2b Cover chamber 2c Bottom chamber 2d Suction pipe 2e Discharge pipe 3 Compression mechanism part 4 Electric motor part 5 Fixed scroll 6 Orbiting scroll 7 Crankshaft 9 Frame 10 Suction chamber 11 Compression chamber 12 Oldham ring 13 Machine oil 17 Lower bearing 18 Condenser 19 Pressure reducing device 19a Pre-stage pressure reducing device 20 Evaporator 21 Gas-liquid separator 24 Four-way valve 25 Second injection valve 25a First hole 25b Second hole 25c Injection pipe 25d Valve body 25e Protrusion 25f Injection passage 26 First injection valve 27 Third injection valve 27a Third hole 27d Valve element 27f Injection passage 30 Injection piping

Claims (4)

A cycle flow path in which a refrigerant is circulated by connecting a scroll compressor, a condenser, a pressure reducing device, and an evaporator sequentially by piping;
A pipe located between the condenser and the pressure reducing device and an injection pipe connecting the scroll compressor;
A first injection valve for opening and closing the flow path of the injection pipe,
The scroll compressor includes an orbiting scroll having a spiral wrap standing on an end plate, a fixed scroll having a spiral wrap standing on an end plate, and an injection pipe connecting the fixed scroll and the injection pipe. And a second injection valve for opening and closing the flow path of the injection pipe,
The second injection valve includes a first hole formed on the wrap side of the end plate of the fixed scroll, a second hole connecting the first hole and the injection pipe, and the second hole. A valve body that is located in the hole and opens and closes the flow path of the injection pipe, and is formed so as to protrude from the valve body, and a part of the valve body always remains in the second position regardless of whether the second injection valve is opened or closed . refrigeration cycle having a projection portion located in the first hole.   The refrigeration cycle according to claim 1, wherein the diameter of the first hole is smaller than the thickness of the wrap of the orbiting scroll.   The refrigeration cycle according to claim 1 or 2, wherein a diameter of the second hole is larger than a diameter of the first hole, and a diameter of the valve body is larger than a diameter of the protrusion. . The refrigerant is HFC32.
When the temperature of the refrigerant discharged from the scroll compressor is equal to or higher than a predetermined value, the first injection valve and the second injection valve are opened,
According to any one of claims 1 to 3, wherein said first injection valve and the second injection valve is closed when the temperature of the refrigerant discharged from the scroll compressor is smaller than the predetermined value Refrigeration cycle.