Compression system and compressor

Abstract

This compression system comprises: a casing; a compressor including a first compression unit that is provided in the casing, that generates an intermediate-pressure refrigerant by compressing a low-pressure refrigerant supplied from outside, and that discharges the intermediate-pressure refrigerant into the casing, and a second compression unit that is provided in the casing, that is set to have a smaller displacement amount than the first compression unit, and that further compresses the intermediate-pressure refrigerant in the casing to generate a high-pressure refrigerant; an evaporator that evaporates the refrigerant that has passed through the compressor, a suction pipe that supplies the low-pressure refrigerant that has passed through the evaporator into the casing; a discharge pipe that discharges the high-pressure refrigerant to the outside of the casing; a bypass pipe that returns the intermediate-pressure refrigerant in the casing to the suction pipe between the evaporator and the first compression unit; and a valve that is provided to the bypass pipe.

Description

Technical Field

[0001] The present disclosure relates to a compression system and a compressor.

[0002] Priority is claimed on Japanese Patent Application No. 2023-113248, filed July 10, 2023, the content of which is incorporated herein by reference.Background Art

[0003] PTL 1 discloses a multistage compression type compressor comprising a first rotation compression element and a second rotation compression element. The compressor sucks a refrigerant compressed and discharged by the first rotation compression element into the second rotation compression element, compresses, and discharges the refrigerant to a gas cooler. Further, the compressor is provided with a bypass circuit that supplies the refrigerant discharged from a first rotation element to an evaporator without decompression.Citation ListPatent Literature

[0004] [PTL 1] Japanese Unexamined Patent Application Publication No. 2004-108334Summary of InventionTechnical Problem

[0005] However, in the compressor disclosed in PTL 1, an intermediate pressure in the compressor is increased due to a difference in displacement between the first rotation compression element and the second rotation compression element at a time of start of operation. When the intermediate pressure is increased, a high pressure on a discharge side of the second rotation compression element is excessively increased, and a thickness of a pipe on a high-pressure side needs to be increased, which causes a problem in that a design constraint is increased.

[0006] The present disclosure is made to solve the above-described problem, and an object of the present disclosure is to provide a compression system and a compressor capable of reducing a design constraint.Solution to Problem

[0007] In order to solve the above problem, according to an embodiment of the present disclosure, there is provided a compression system including: a compressor that includes a casing, a first compression portion that is provided in the casing, that compresses a low-pressure refrigerant supplied from an outside to generate an intermediate-pressure refrigerant, and that discharges the intermediate-pressure refrigerant into the casing, and a second compression portion that is provided in the casing, that is set to have a smaller displacement than the first compression portion, and that further compresses the intermediate-pressure refrigerant in the casing to generate a high-pressure refrigerant; an evaporator that evaporates the refrigerant having passed through the compressor; a suction pipe that supplies the low-pressure refrigerant having passed through the evaporator into the casing; a discharge pipe that discharges the high-pressure refrigerant to an outside of the casing; a bypass pipe that returns the intermediate-pressure refrigerant in the casing to the suction pipe between the evaporator and the first compression portion; and a valve that is provided in the bypass pipe.

[0008] According to another embodiment of the present disclosure, there is provided a compressor including: a casing; a suction port provided in the casing; a first compression portion that is provided in the casing, that compresses a low-pressure refrigerant supplied from an outside through the suction port to generate an intermediate-pressure refrigerant, and that discharges the intermediate-pressure refrigerant into the casing; a second compression portion that is provided in the casing, that is set to have a smaller displacement than the first compression portion, and that further compresses the intermediate-pressure refrigerant in the casing to generate a high-pressure refrigerant; a discharge port that is provided in the casing and that discharges the high-pressure refrigerant to an outside of the casing; a shaft that is disposed in the casing, to which the first compression portion is connected on one side in an axial direction and to which the second compression portion is connected on the other side in the axial direction; a motor that is disposed in the casing, has a rotor provided on a radial inner side and a stator provided on a radial outer side, and that rotates the shaft; and an intermediate-pressure discharge port that discharges the intermediate-pressure refrigerant in the casing to the outside of the casing, in which the intermediate-pressure discharge port is provided on the other side in the axial direction with respect to the stator.Advantageous Effects of Invention

[0009] According to the compression system and the compressor of the present disclosure, a design constraint can be reduced.Brief Description of Drawings

[0010] FIG. 1 is a schematic diagram of a compression system according to an embodiment of the present disclosure. FIG. 2 is a longitudinal sectional view of a compressor according to an embodiment of the present disclosure. FIG. 3 is a view of the compressor according to the embodiment of the present disclosure as viewed from above. FIG. 4 is a functional block diagram of the control device according to the embodiment of the present disclosure. FIG. 5 is a flowchart showing an open and close procedure of a bypass pipe according to the embodiment of the present disclosure. FIG. 6 is a diagram showing a case where the bypass pipe according to the embodiment of the present disclosure is in an open state. FIG. 7 is a diagram showing a case where the bypass pipe according to the embodiment of the present disclosure is in a closed state. FIG. 8 is a hardware configuration diagram according to the embodiment of the present disclosure. Description of Embodiments(Configuration of Compression System)

[0011] Hereinafter, a compression system 1 according to the embodiment of the present disclosure will be described with reference to FIGS. 1 to 7.

[0012] The compression system 1 shown in FIG. 1 is used, for example, in an air conditioner for refrigeration and freezing. The compression system 1 compresses a refrigerant that is a gas, such as carbon dioxide. The compression system 1 includes a refrigerant pipe 20 that is a pipe through which a refrigerant flows and circulates, a compressor 2 that is disposed on the refrigerant pipe 20, a condenser 3, an expansion valve 4, an evaporator 5 (evaporator), an accumulator 6, a sub-accumulator 7, a valve 8, a sensor 9, and a control device 80. The compressor 2, the condenser 3, the expansion valve 4, the evaporator 5, the accumulator 6, and the sub-accumulator 7 are arranged in this order on the refrigerant pipe 20. In addition, during operation of the compression system 1, the refrigerant also passes through each device in this order.(Compressor)

[0013] The compressor 2 pumps the refrigerant in the refrigerant pipe 20. In this way, the pressure and temperature of the refrigerant after passing through the compressor 2 rise as compared with the refrigerant before passing through the compressor 2. The details of the configuration of the compressor 2 will be described later.(Condenser)

[0014] The condenser 3 performs heat exchange between the refrigerant flowing into the condenser 3 and a heat medium supplied from the outside.(Expansion Valve)

[0015] The expansion valve 4 rapidly lowers a temperature by reducing the pressure of the refrigerant passing through the expansion valve 4.(Evaporator)

[0016] The evaporator 5 evaporates the refrigerant that has passed through the compressor 2. The evaporator 5 performs heat exchange between the refrigerant flowing into the evaporator 5 and the heat medium supplied from the outside. As a result, the refrigerant flowing into the evaporator 5 evaporates. The refrigerant that has passed through the evaporator 5 passes through the accumulator 6 and the sub-accumulator 7 in this order.(Accumulator)

[0017] The accumulator 6 is provided between the evaporator 5 and the compressor 2 on the refrigerant pipe 20, and is capable of temporarily storing the refrigerant.(Sub-accumulator)

[0018] The sub-accumulator 7 is provided between the accumulator 6 and the compressor 2 on the refrigerant pipe 20, and is capable of temporarily storing the refrigerant, similarly to the accumulator 6. A capacity of the sub-accumulator 7 is smaller than a capacity of the accumulator 6. The sub-accumulator 7 is disposed at a position close to the compressor 2.(Configuration of Compressor)

[0019] Subsequently, the configuration of the compressor 2 will be described.

[0020] As shown in FIG. 2, in the present embodiment, the compressor 2 is disposed to extend in a vertical up-down direction.

[0021] Hereinafter, the vertical up-down direction will be simply referred to as an "up-down direction Dv". A reference numeral "Dvu" is assigned to an upper side, and a reference numeral "Dvd" is assigned to a lower side.

[0022] The compressor 2 includes a casing 30, a shaft 40, a motor 50, a suction port 10, a first compression portion 60, a second compression portion 70, a drive bush 11, a discharge port 12, an intermediate-pressure discharge port 13, and a valve 8.(Casing)

[0023] The casing 30 includes a casing main body portion 31, a first lid portion 32, and a second lid portion 33. The casing main body portion 31 is formed in a cylindrical shape and is disposed to extend in the up-down direction Dv.

[0024] Hereinafter, a central axis of the casing main body portion 31 may be simply referred to as an "axis O". Since the axis O extends in the up-down direction Dv, one side in an O-axis direction may be described as a lower side Dvd, and the other side in the O-axis direction may be described as an upper side Dvu. In addition, a radial direction about the axis O may be simply referred to as a "radial direction", and a circumferential direction about the axis O may be simply referred to as a "circumferential direction".

[0025] The first lid portion 32 closes an opening of the casing main body portion 31 on the lower side Dvd. The second lid portion 33 closes an opening of the casing main body portion 31 on the upper side Dvu.

[0026] The casing 30 configured in this manner seals an internal space. In addition, an oil sump 34 is formed at a bottom portion of the casing 30 on the lower side Dvd.(Shaft)

[0027] The shaft 40 is disposed to extend up and down in the casing 30. The shaft 40 includes a shaft body 41, a first eccentric shaft portion 42, and a second eccentric shaft portion 43. The shaft body 41 is formed in a cylindrical shape about the axis O.

[0028] The first eccentric shaft portion 42 is provided on one side (lower side Dvd) of the shaft body 41 in the O-axis direction. The first eccentric shaft portion 42 are provided two in number and are arranged up and down along the O-axis direction. The first eccentric shaft portion 42 has a cylindrical shape about an eccentric axis that is parallel to the axis O and that extends at a position shifted from the axis O in the radial direction.

[0029] In addition, the second eccentric shaft portion 43 is provided on the other side (upper side Dvu) of the shaft body 41 in the O-axis direction. The second eccentric shaft portion 43 protrudes from the shaft body 41 toward the other side in the O-axis direction. The second eccentric shaft portion 43 has a cylindrical shape about an eccentric axis that is parallel to the axis O and that extends at a position shifted from the axis O in the radial direction.(Motor)

[0030] The motor 50 is disposed in the casing 30. The motor 50 includes a rotor 51 that is provided on a radial inner side and a stator 52 that is provided on radial outer side.(Rotor)

[0031] The rotor 51 is fixed to the shaft body 41. The rotor 51 is formed in a cylindrical shape about the axis O.(Stator)

[0032] The stator 52 covers the rotor 51 from an outer peripheral side. The stator 52 is fixed to an inner peripheral surface of the casing main body portion 31 and is located at a middle portion of the casing main body portion 31 in the O-axis direction. By energizing the stator 52, an electromagnetic force is generated between the stator 52 and the rotor 51, and a rotational force about the axis O is applied to the rotor 51. Accordingly, the shaft 40 rotates about the axis O.(Suction Port)

[0033] The casing 30 is provided with a suction port 10 that guides the refrigerant from the outside into the casing 30. More specifically, the suction port 10 is provided at an end part of the casing main body portion 31 on the lower side Dvd and protrudes from the casing main body portion 31 to the radial outer side.(First Compression Portion)

[0034] The first compression portion 60 is provided in the casing 30. The first compression portion 60 compresses the refrigerant supplied from the outside of the casing 30 through the suction port 10.

[0035] Hereinafter, the refrigerant supplied from the suction pipe 21 to the first compression portion 60 may be referred to as "low-pressure refrigerant", and the refrigerant generated by the first compression portion 60 that compresses the low-pressure refrigerant may be referred to as "intermediate-pressure refrigerant". In addition, the pressure of the low-pressure refrigerant may be referred to as "low pressure", and the pressure of the intermediate-pressure refrigerant may be referred to as "intermediate pressure".

[0036] The first compression portion 60 discharges the generated intermediate-pressure refrigerant into the casing 30. The first compression portion 60 is connected to an end part of the shaft 40 on one side (lower side Dvd) in the O-axis direction.

[0037] The first compression portion 60 of the present embodiment is a so-called rotary compression portion and is disposed in the oil sump 34 in the casing 30. The first compression portion 60 includes a plurality of disk-shaped cylinders 61, a separator plate 62, and a piston rotor 63.

[0038] The cylinders 61 are provided two in number and are arranged up and down along the O-axis direction. The number of cylinders 61 may be three or more or may be one.

[0039] A compression chamber 65 is formed inside each of the cylinders 61. The compression chamber 65 accommodates the piston rotor 63.

[0040] In addition, the separator plate 62 is disposed between the cylinders 61 to be sandwiched up and down by each cylinder 61. The separator plate 62 separates the compression chambers 65 from each other.

[0041] In each of the cylinders 61, a suction hole 64 communicating with the compression chamber 65 therein is formed. The suction hole 64 allows the refrigerant supplied from the outside through the suction port 10 to flow in each of the cylinders 61.

[0042] The piston rotor 63 is formed in a cylindrical shape having an outer diameter smaller than an inner diameter of the cylinder 61. The piston rotor 63 is disposed inside the cylinder 61. Further, the first eccentric shaft portion 42 is inserted into the piston rotor 63. The piston rotor 63 rotates eccentrically with respect to the axis O as the shaft 40 rotates.

[0043] A discharge hole (not shown) is provided in the first compression portion 60. Through the discharge hole, the refrigerant (intermediate-pressure refrigerant) compressed at the first compression portion 60 is discharged to an internal space of the casing 30 with an intermediate pressure, that is, a space above the cylinder 61.(Second Compression Portion)

[0044] The second compression portion 70 is provided in the casing 30. The second compression portion 70 further compresses the intermediate-pressure refrigerant in the casing 30.

[0045] Hereinafter, the refrigerant generated by the second compression portion 70 that further compresses the intermediate-pressure refrigerant may be referred to as "high-pressure refrigerant". In addition, the pressure of the high-pressure refrigerant may be referred to as "high pressure".

[0046] The second compression portion 70 is connected to an end part of the shaft 40 on the other side (upper side Dvu) in the O-axis direction.

[0047] The second compression portion 70 of the present embodiment is a so-called scroll compression portion and is disposed above the motor 50 in the casing 30. The second compression portion 70 includes a fixed scroll 71, a movable scroll 72, and a suction portion 78.(Fixed scroll)

[0048] The fixed scroll 71 includes a disk-shaped first end plate 73 about the axis O and a first spiral plate 74 that is provided on one side (lower side Dvd) of the first end plate 73 in the O-axis direction. The first spiral plate 74 extends spirally about the axis O. The fixed scroll 71 is fixed to the casing main body portion 31 via a main bearing 90.(Movable Scroll)

[0049] The movable scroll 72 includes a disk-shaped second end plate 75, a second spiral plate 76 that is provided on the other side (upper side Dvu) of the second end plate 75 in the O-axis direction, and a boss portion 77. The second spiral plate 76 extends spirally about the axis O. A dimension of the second spiral plate 76 in the O-axis direction is the same as a dimension of the first spiral plate 74 in the O-axis direction. As the first spiral plate 74 and the second spiral plate 76 mesh with each other from the O-axis direction, a compression chamber 79 is formed therebetween.

[0050] The boss portion 77 is a cylindrical portion that protrudes from the second end plate 75 toward one side (lower side Dvd) in the O-axis direction. The boss portion 77 is attached to the second eccentric shaft portion 43 of the shaft 40 via the drive bush 11. As the second eccentric shaft portion 43 rotates about the axis O, a power is transmitted to the movable scroll 72 through the drive bush 11. As a result, the movable scroll 72 is restricted from moving by an Oldham link 91 and turns about the axis O.(Suction Portion)

[0051] In addition, as shown in FIG. 3, the second compression portion 70 is provided with a suction portion 78, which is a hole that sucks the intermediate-pressure refrigerant generated by the first compression portion 60 and guides the intermediate-pressure refrigerant into the compression chamber 79 therein. The suction portion 78 is formed to extend from an outer peripheral side of the second compression portion 70 to an inside of the first end plate 73, for example. In the example shown in the drawing, the suction portion 78 is formed two in number in the first end plate 73. The two suction portions 78 are disposed to be symmetrical about the axis O in a view in the O-axis direction (plan view).

[0052] As the movable scroll 72 turns, the volume of the compression chamber 79 changes with time, the intermediate-pressure refrigerant is compressed while being sent from a radial outer side to an inner side in the compression chamber 79, and the refrigerant in a high-pressure state is generated. The high-pressure refrigerant generated by the second compression portion 70 is discharged into the casing 30.(Discharge Port)

[0053] A discharge port 12 that discharges the high-pressure refrigerant generated by the second compression portion 70 to the outside of the casing 30 is provided on the other side (upper side Dvu) of the casing 30 in the O-axis direction. More specifically, the discharge port 12 is provided in the second lid portion 33 of the casing 30 and extends from the second lid portion 33 along the O-axis direction. The discharge port 12 allows communication between the inside and the outside of the casing 30.(Intermediate-pressure Discharge Port)

[0054] An intermediate-pressure discharge port 13 that discharges the intermediate-pressure refrigerant in the casing 30 to the outside of the casing 30 is provided on the other side (upper side Dvu) of the casing 30 in the O-axis direction. The intermediate-pressure discharge port 13 is provided on the other side (upper side Dvu) of the stator 52 in the O-axis direction. In the example shown in the drawing, the intermediate-pressure discharge port 13 is provided on the other side (upper side Dvu) in the O-axis direction with respect to the fixed scroll 71 of the second compression portion 70. The intermediate-pressure discharge port 13 extends from the second lid portion 33 of the casing 30 to the radial outer side.

[0055] Further, the intermediate-pressure discharge port 13 is disposed at a circumferential position (phase) different from the suction portion 78 of the second compression portion 70 as viewed in the O-axis direction (upward). In the example shown in the drawing, the intermediate-pressure discharge port 13 is disposed at a position that is phase-separated by about 90 degrees from the suction portion 78 about the axis O.(Refrigerant Pipe)

[0056] Subsequently, the configuration of the refrigerant will be described in detail. As shown in FIG. 1, the refrigerant pipe 20 includes a suction pipe 21, a discharge pipe 22, an intermediate pipe 23, and a bypass pipe 24.(Suction Pipe)

[0057] The suction pipe 21 connects the evaporator 5 and the compressor 2. The suction pipe 21 is connected to the suction port 10. The suction pipe 21 supplies the low-pressure refrigerant that has passed through the evaporator 5 to the casing 30 of the compressor 2. In addition, the suction pipe 21 is provided with the accumulator 6 and the sub-accumulator 7 described above. The accumulator 6 is provided between the evaporator 5 and the first compression portion 60 on the suction pipe 21, and the sub-accumulator 7 is provided between the accumulator 6 and the first compression portion 60 on the suction pipe 21.(Discharge Pipe)

[0058] The discharge pipe 22 connects the compressor 2 and the condenser 3. The discharge pipe 22 is connected to the discharge port 12 and discharges the refrigerant (high-pressure refrigerant) compressed by the compressor 2 to the outside of the casing 30. The refrigerant discharged from the compressor 2 is supplied to the condenser 3 through the discharge pipe 22.(Intermediate Pipe)

[0059] The intermediate pipe 23 connects the condenser 3 and the evaporator 5. The refrigerant condensed in the condenser 3 is sent to the evaporator 5. The expansion valve 4 is provided in the intermediate pipe 23.(Bypass Pipe)

[0060] The bypass pipe 24 connects the compressor 2 and the suction pipe 21. The bypass pipe 24 is connected to the intermediate-pressure discharge port 13. The bypass pipe 24 returns the intermediate-pressure refrigerant in the casing 30 to the suction pipe 21. In the present embodiment, the bypass pipe 24 is connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21.(Valve)

[0061] The bypass pipe 24 is provided with the valve 8 that opens and closes the bypass pipe 24. The valve 8 is a so-called solenoid valve and is controlled by the control device 80 described below.(Sensor)

[0062] The sensor 9 detects a pressure when the refrigerant is supplied to the compressor 2. The sensor 9 is provided in the suction pipe 21. The sensor 9 detects the pressure of the low-pressure refrigerant supplied to the first compression portion 60 and transmits the detected pressure to the control device 80.(Control Device)

[0063] The control device 80 controls each device constituting the above-described compression system 1.

[0064] As shown in FIG. 4, the control device 80 includes, for example, each functional unit of a reception unit 81, a pressure determination unit 82, and a valve control unit 83.

[0065] The reception unit 81 receives information including a pressure value of the low-pressure refrigerant flowing through the suction pipe 21, which is transmitted from the sensor 9.

[0066] The pressure determination unit 82 determines whether or not the pressure (pressure of the refrigerant flowing through the suction pipe 21) detected by the sensor 9 is equal to or less than a threshold value.

[0067] The valve control unit 83 controls the valve 8 to open and close the bypass pipe 24. More specifically, the valve control unit 83 opens the valve 8 to put the bypass pipe 24 in the open state when compressor 2 starts the operation, and closes the valve 8 to put the bypass pipe 24 in the open state when the compressor 2 reaches the steady operation.(Open and Close Procedure of Bypass Pipe)

[0068] The bypass pipe 24 is opened and closed at the start of operation of the compression system 1. The open and close procedure of the bypass pipe 24 will be described with reference to the flowchart of FIG. 5.

[0069] First, before the operation of the compression system 1 is started, the valve control unit 83 opens the valve 8 to put the bypass pipe 24 in the open state (step S10). In this state, the compression system 1 is operated. As a result, as shown in FIG. 6, the refrigerant starts to flow in the refrigerant pipe 20 and circulate in a cooling system. Hereinafter, the refrigerant pipe 20 in the open state is shown by a solid line, and the refrigerant pipe 20 in the closed state is shown by a broken line. Further, a direction in which the refrigerant flows is shown by an arrow.

[0070] Since the bypass pipe 24 is in the open state, a pressure difference between an inside of the casing 30 and an inside of the suction pipe 21 is almost eliminated, and the compression by the first compression portion 60 is canceled. That is, the first compression portion 60 can be regarded as not performing work. Usually, immediately after the start of the operation, a pressure in the casing 30 rapidly increases, and the pressure on the high-pressure side in the casing 30 may exceed a limit pressure (design pressure) of the discharge pipe 22, so that complicated operation control is required. However, in the present embodiment, by putting the bypass pipe 24 in the open state, a boost pressure is reduced, and the rapid increase in the pressure in the casing 30 is suppressed, and the pressure in the casing 30 can be limited to the limit pressure or less of the discharge pipe 22.

[0071] In addition, at this time, the sensor 9 detects the pressure of the suction pipe 21 through which the low-pressure refrigerant supplied to the first compression portion 60 flows, and transmits information including the pressure of the suction pipe 21 to the control device 80. The pressure detection and the information transmission by the sensor 9 are performed periodically, for example, at certain time intervals. Then, the reception unit 81 of the control device 80 receives the transmitted pressure of the suction pipe 21 (step S11).

[0072] After step S11, the pressure determination unit 82 determines whether or not the pressure of the suction pipe 21 is equal to or less than a preset threshold value (step S12). When the pressure of the suction pipe 21 is not equal to or less than the threshold value (step S12; NO), the process returns to step S11. When the pressure of the suction pipe 21 is equal to or less than the threshold value (step S12; YES), the valve control unit 83 closes the valve 8 to put the bypass pipe 24 in the closed state as shown in FIG. 7 (step S13).

[0073] Here, there is a correlation between the pressure of the suction pipe 21 (low pressure of the low-pressure refrigerant), the pressure of the casing 30 (intermediate pressure of the intermediate-pressure refrigerant), and the pressure of the discharge pipe 22 (high pressure of the high-pressure refrigerant), and the higher the low pressure, the higher the intermediate pressure and the high pressure. The preset threshold value is a pressure value of the low pressure such that the upper limit of the high pressure reaches the limit pressure of the discharge pipe 22 when the bypass pipe 24 is in the closed state. When the pressure of the suction pipe 21 is a value lower than the threshold value (step S12; YES), the high pressure is equal to or less than the limit pressure, and the compression system 1 can be stably operated (steady operation).

[0074] In step S13, when the low pressure is lower than the threshold value, the bypass pipe 24 is put in the closed state, so that transition to the steady operation is safely performed without the high pressure exceeding the limit pressure.

[0075] In this manner, the bypass pipe 24 is opened and closed.(Operations and Effects)

[0076] The compression system 1 and the compressor 2 of the present embodiment can exhibit the following effects.

[0077] In the present embodiment, the bypass pipe 24 returns the intermediate-pressure refrigerant in the casing 30 to the suction pipe 21 between the evaporator 5 and the first compression portion 60. The valve 8 is provided in the bypass pipe 24.

[0078] As a result, by opening the valve 8 to put the bypass pipe 24 in the open state, the intermediate-pressure refrigerant in the casing 30 can be released to the suction pipe 21. Further, since the bypass pipe 24 directly guides the intermediate-pressure refrigerant to the suction pipe 21 without passing through the condenser 3, the pressure difference between the intermediate-pressure refrigerant and the low-pressure refrigerant can be reduced, and the overall pressure increase in the casing 30 can be suppressed. Therefore, since an increase in the pressure on the high-pressure side in the casing 30 is suppressed, it is possible to easily prevent the internal pressure of the discharge pipe 22 from exceeding the limit pressure (design pressure) of the discharge pipe 22. Therefore, it is not necessary to increase the thickness of the discharge pipe 22 in order to ensure the pressure resistance of the discharge pipe 22. Therefore, a design constraint can be reduced.

[0079] In addition, as described above, since the bypass pipe 24 is provided to directly guide the intermediate-pressure refrigerant to the suction pipe 21 without passing through the condenser 3, the intermediate-pressure refrigerant bypassed from the inside of the casing 30 is returned to a position close to the first compression portion 60 on the suction pipe 21. Therefore, a pressure loss of the intermediate-pressure refrigerant flowing through the bypass pipe 24 can be reduced.

[0080] In the present embodiment, the bypass pipe 24 is connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21.

[0081] The sub-accumulator 7 prevents the low-pressure refrigerant from flowing back from the first compression portion 60. In addition, since a capacity of the sub-accumulator 7 is smaller than a capacity of the accumulator 6, an installation location of the sub-accumulator 7 can be freely selected as compared with the accumulator 6. Therefore, the sub-accumulator 7 can be disposed at a position close to the first compression portion 60. In addition, in the present embodiment, the bypass pipe 24 is connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21. Therefore, the compression system 1 of the present embodiment can reduce the pressure loss by returning the intermediate-pressure refrigerant bypassed from the inside of the casing 30 to the position close to the first compression portion 60 while preventing the backflow of the low-pressure refrigerant.

[0082] In the present embodiment, the compression system 1 further includes the control device 80 that opens the valve 8 to put the bypass pipe 24 in the open state when the compressor 2 starts the operation.

[0083] Usually, at the start of the operation, the intermediate pressure in the casing 30 is rapidly increased due to a difference in displacement between the first compression portion 60 and the second compression portion 70, and the pressure on the high-pressure side (the pressure of the discharge pipe 22) may exceed the limit pressure, which requires complicated operation control. In the present embodiment, when the compressor 2 starts the operation, the valve 8 is opened to put the bypass pipe 24 to the open state, so that the intermediate pressure in the casing 30 is released to the suction pipe 21. As a result, the pressure difference between the low-pressure side and the intermediate-pressure side in the casing 30 can be reduced, and the overall pressure increase in the casing 30 can be suppressed. Therefore, the increase in the pressure on the high-pressure side in the casing 30 can be suppressed at the start of the operation at which an increase in the pressure is likely to be increased.

[0084] Further, the control device 80 closes the valve 8 to put the bypass pipe 24 in the closed state when the compressor 2 reaches the steady operation.

[0085] In the compressor 2, the pressure is stabilized after a predetermined time has elapsed (steady operation). In the steady operation, since the pressure of the discharge pipe 22 is stabilized at a state lower than the limit pressure, it is not necessary to release the intermediate pressure in the casing 30 from the bypass pipe 24. The control device 80 closes the valve 8 to put the bypass pipe 24 in the closed state when the compressor 2 reaches the steady operation.

[0086] In the present embodiment, the control device 80 determines that the compressor 2 has transitioned to the steady operation and closes the valve 8 in a case where the pressure of the suction pipe 21 detected by the sensor 9 is lower than the preset threshold value, but the present disclosure is not limited to this. For example, the control device 80 may determine that the compressor 2 has transitioned to the steady operation and close the valve 8 in a case where the predetermined time has elapsed from the start of the operation of the compressor 2.

[0087] In the present embodiment, the compressor 2 discharges the intermediate-pressure refrigerant in the casing 30 to the outside of the casing 30. The intermediate-pressure discharge port 13 is provided. The bypass pipe 24 is connected to the intermediate-pressure discharge port 13. The intermediate-pressure discharge port 13 is provided on the other side (upper side Dvu) of the stator 52 in the O-axis direction.

[0088] As a result, the intermediate-pressure refrigerant can be released to the outside from the intermediate-pressure discharge port 13, and the overall pressure increase in the casing 30 can be suppressed.

[0089] For example, as in the present embodiment, when the compressor 2 is disposed to extend in the up-down direction Dv and the other side in the O-axis direction is the upper side Dvu, a lubricant is collected in a lower part of the casing 30. Therefore, an oil surface S is positioned below an upper end of the stator 52. In the present embodiment, since the intermediate-pressure discharge port 13 is positioned above the stator 52, the intermediate-pressure refrigerant can be efficiently discharged to the outside without interference from the oil surface S. Therefore, the overall pressure increase in the casing 30 can be further suppressed.

[0090] As described above, since the overall pressure increase in the casing 30 is suppressed, the increase in the pressure on the high-pressure side in the casing 30 is favorably suppressed. Therefore, it is not necessary to increase the thickness of the discharge port 12 in order to ensure the pressure resistance.

[0091] In addition, since the bypass pipe 24 is connected to the intermediate-pressure discharge port 13 as the entire compression system 1, the bypass pipe 24 is positioned above the upper end of the stator 52. Therefore, the intermediate-pressure refrigerant can be returned to the suction pipe 21 without interference from the oil surface S. Therefore, the compression system 1 can efficiently return the intermediate-pressure refrigerant to the suction pipe 21.

[0092] In the present embodiment, the second compression portion 70 is a scroll compression portion and has the suction portion 78 that sucks the intermediate-pressure refrigerant into the inside. The intermediate-pressure discharge port 13 is disposed at a circumferential position different from the suction portion 78 as viewed in the O-axis direction.

[0093] As a result, the intermediate-pressure discharge port 13 and the suction portion 78 can be disposed to be spaced from each other. Therefore, it is possible to suppress a situation where most of the intermediate-pressure refrigerant is sucked by the suction portion 78 before being supplied to the intermediate-pressure discharge port 13. Therefore, the intermediate-pressure refrigerant can be efficiently guided to the intermediate-pressure discharge port 13, and a sufficient amount of the intermediate-pressure refrigerant to reduce the pressure in the casing 30 through the bypass pipe 24 can be bypassed.

[0094] In the present embodiment, the intermediate-pressure discharge port 13 to which the bypass pipe 24 is connected is provided on the other side (upper side Dvu) in the O-axis direction with respect to the fixed scroll 71 of the second compression portion 70.

[0095] As a result, the intermediate-pressure refrigerant can be supplied from the first compression portion 60 to the second compression portion 70 without hindering the flow of the refrigerant.(Hardware Configuration)

[0096] The control device 80 according to the above-described embodiment is mounted in a computer as shown in FIG. 8. FIG. 8 is an example of a schematic block diagram showing a configuration of a computer in which the control device 80 according to each embodiment is mounted. The computer 1100 includes a processor 1110, a main memory 1120, a storage 1130, and an interface 1140.

[0097] Then, the operations of the respective functional units of the control device 80 are stored in the storage 1130 in the form of a program. The processor 1110 reads the program from the storage 1130, develops the read program in the main memory 1120, and executes the above-described process in accordance with the program. In addition, the processor 1110 secures a storage area in the main memory 1120 according to the program.

[0098] The program may be intended to realize some of functions fulfilled by the computer 1100. For example, the program may fulfill a function in combination with another program previously stored in the storage 1130, or in combination with another program installed in another device. In addition, the computer 1100 may include a custom large scale integrated circuit (LSI) such as a programmable logic device (PLD) in addition to or in place of the above configuration. Examples of the PLD include a programmable array logic (PAL), a generic array logic (GAL), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). In this case, functions that are realized by the processor 1110 may be partially or entirely realized by the integrated circuit.

[0099] As an example of the storage 1130, a magnetic disk, a magneto-optical disk, or a semiconductor memory can be used. The storage 1130 may be an internal medium directly connected to a bus of the computer 1100, or may be an external medium connected to the computer 1100 via the interface 1140 or a communication line. In addition, when this program is distributed to the computer 1100 via the communication line, the computer 1100 receiving the distributed program may develop the program in the main memory 1120 to execute the above-described process. The storage 1130 may be a non-transitory tangible storage medium.

[0100] In addition, the program may be used to partially realize the above-described functions. In addition, the program may be a so-called difference file (difference program) that realizes the above-described functions in combination with another program previously stored in the storage 1130.(Other Embodiments)

[0101] The embodiments of the present disclosure have been described in detail with reference to the drawings hereinbefore. However, the specific configuration is not limited to the embodiments, and includes design changes and the like within a scope not departing from the gist of the present disclosure.

[0102] In the above-described embodiment, the first compression portion 60 is the rotary compression portion and the second compression portion 70 is the scroll compression portion, but the present disclosure is not limited to this. For example, the first compression portion 60 may be the scroll compression portion and the second compression portion 70 may be the rotary compression portion. In addition, both the first compression portion 60 and the second compression portion 70 may be the rotary compression portions. In addition, both the first compression portion 60 and the second compression portion 70 may be the scroll compression portions.

[0103] In the present embodiment, the intermediate-pressure discharge port 13 to which the bypass pipe 24 is connected is provided on the other side (upper side Dvu) in the O-axis direction with respect to the fixed scroll 71 of the second compression portion 70, but the present disclosure is not limited to this. The intermediate-pressure discharge port 13 may be provided between the stator 52 and the suction portion 78 of the second compression portion 70. In this case, the intermediate-pressure refrigerant can be guided to the intermediate-pressure discharge port 13 in each case before being sucked into the suction portion 78, and can be bypassed to the suction pipe 21 through the bypass pipe 24.<Additional Notes>

[0104] The compression system 1 and the compressor 2 according to each embodiment are understood as follows.

[0105] (1) A compression system 1 according to a first aspect includes: a compressor 2 that includes a casing 30, a first compression portion 60 that is provided in the casing 30, that compresses a low-pressure refrigerant supplied from an outside to generate an intermediate-pressure refrigerant, and that discharges the intermediate-pressure refrigerant into the casing 30, and a second compression portion 70 that is provided in the casing 30, that is set to have a smaller displacement than the first compression portion 60, and that further compresses the intermediate-pressure refrigerant in the casing 30 to generate a high-pressure refrigerant; an evaporator 5 that evaporates the refrigerant having passed through the compressor 2; a suction pipe 21 that supplies the low-pressure refrigerant having passed through the evaporator 5 into the casing 30; a discharge pipe 22 that discharges the high-pressure refrigerant to an outside of the casing 30; a bypass pipe 24 that returns the intermediate-pressure refrigerant in the casing 30 to the suction pipe 21 between the evaporator 5 and the first compression portion 60; and a valve 8 that is provided in the bypass pipe 24.

[0106] As a result, by opening the valve 8 to put the bypass pipe 24 in the open state, the intermediate-pressure refrigerant in the casing 30 can be released to the suction pipe 21. Further, since the bypass pipe 24 directly guides the intermediate-pressure refrigerant to the suction pipe 21 without passing through the condenser 3, the pressure difference between the intermediate-pressure refrigerant and the low-pressure refrigerant can be reduced, and the overall pressure increase in the casing 30 can be suppressed. Therefore, since an increase in the pressure on the high-pressure side in the casing 30 is suppressed, it is possible to easily prevent the internal pressure of the discharge pipe 22 from exceeding the limit pressure (design pressure) of the discharge pipe 22. Therefore, it is not necessary to increase the thickness of the discharge pipe 22 in order to ensure the pressure resistance of the discharge pipe 22.

[0107] (2) In a compression system 1 according to a second aspect, in the compression system 1 according to the first aspect further includes: an accumulator 6 that is provided between the evaporator 5 and the first compression portion 60 on the suction pipe 21 and that is capable of storing the refrigerant; and a sub-accumulator 7 that is provided between the accumulator 6 and the first compression portion 60 on the suction pipe 21, that is capable of storing the refrigerant, and that has a smaller capacity than the accumulator 6, in which the bypass pipe 24 may be connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21.

[0108] The sub-accumulator 7 prevents the low-pressure refrigerant from flowing back from the first compression portion 60. In addition, since a capacity of the sub-accumulator 7 is smaller than a capacity of the accumulator 6, an installation location of the sub-accumulator 7 can be freely selected as compared with the accumulator 6. Therefore, the sub-accumulator 7 can be disposed at a position close to the first compression portion 60. Further, in the present aspect, the bypass pipe 24 is connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21. Therefore, the compression system 1 of the present aspect can reduce the pressure loss by returning the intermediate-pressure refrigerant bypassed from the inside of the casing 30 to the position close to the first compression portion 60.

[0109] (3) In a compression system 1 according to a third aspect, the compression system 1 according to the first or second aspect further includes: a control device 80 that opens the valve 8 to put the bypass pipe 24 in an open state when the compressor 2 starts an operation.

[0110] Usually, at the start of the operation, the intermediate pressure in the casing 30 is rapidly increased due to a difference in displacement between the first compression portion 60 and the second compression portion 70, and the pressure on the high-pressure side (the pressure of the discharge pipe 22) may exceed the limit pressure, which requires complicated operation control. In the present aspect, when the compressor 2 starts the operation, the valve 8 is opened to put the bypass pipe 24 to the open state, so that the intermediate pressure in the casing 30 is released to the suction pipe 21. As a result, the pressure difference between the low-pressure side and the intermediate-pressure side in the casing 30 can be reduced, and the overall pressure increase in the casing 30 can be suppressed. Therefore, the increase in the pressure on the high-pressure side in the casing 30 can be suppressed at the start of the operation at which the pressure is likely to be increased.

[0111] (4) In a compression system 1 according to a fourth aspect, in the compression system 1 according to any one of the first to third aspects, the compressor 2 further includes a shaft 40 that is disposed in the casing 30, to which the first compression portion 60 is connected on one side in an O-axis direction and to which the second compression portion 70 is connected on the other side in the O-axis direction, a motor 50 that is disposed in the casing 30, has a rotor 51 provided on a radial inner side and a stator 52 provided on a radial outer side, and that rotates the shaft 40, and an intermediate-pressure discharge port 13 to which the bypass pipe 24 is connected, and the intermediate-pressure discharge port 13 is provided on the other side in the O-axis direction with respect to the stator 52.

[0112] For example, when the compressor 2 is disposed to extend in the up-down direction Dv and the other side in the O-axis direction is the upper side Dvu, the lubricant is collected in a lower part of the casing 30. Therefore, an oil surface S is positioned below an upper end of the stator 52. In the present aspect, since the intermediate-pressure discharge port 13 is positioned above the stator 52, the intermediate-pressure refrigerant can be returned to the suction pipe 21 without interference from the oil surface S.

[0113] (5) In a compression system 1 according to a fifth aspect, in the compression system 1 according to the fourth aspect, the second compression portion 70 is a scroll compression portion and has a suction portion 78 that sucks the intermediate-pressure refrigerant therein, and the intermediate-pressure discharge port 13 is disposed at a circumferential position different from the suction portion 78 as viewed in the O-axis direction.

[0114] As a result, the intermediate-pressure discharge port 13 and the suction portion 78 can be disposed to be spaced from each other. Therefore, it is possible to suppress a situation where most of the intermediate-pressure refrigerant is sucked by the suction portion 78 before being supplied to the intermediate-pressure discharge port 13.

[0115] (6) A compressor 2 according to a sixth aspect includes: a casing 30; a suction port 10 provided in the casing 30; a first compression portion 60 that is provided in the casing 30, that compresses a low-pressure refrigerant supplied from an outside through the suction port 10 to generate an intermediate-pressure refrigerant, and that discharges the intermediate-pressure refrigerant into the casing 30; a second compression portion 70 that is provided in the casing 30, that is set to have a smaller displacement than the first compression portion 60, and that further compresses the intermediate-pressure refrigerant in the casing 30 to generate a high-pressure refrigerant; a discharge port 12 that is provided in the casing 30 and that discharges the high-pressure refrigerant to an outside of the casing 30; a shaft 40 that is disposed in the casing 30, to which the first compression portion 60 is connected on one side in an O-axis direction and to which the second compression portion 70 is connected on the other side in the O-axis direction; a motor 50 that is disposed in the casing 30, has a rotor 51 provided on a radial inner side and a stator 52 provided on a radial outer side, and that rotates the shaft 40; and an intermediate-pressure discharge port 13 that discharges the intermediate-pressure refrigerant in the casing 30 to the outside of the casing 30, in which the intermediate-pressure discharge port 13 is provided on the other side in the O-axis direction with respect to the stator 52.

[0116] As a result, the intermediate-pressure refrigerant can be released to the outside from the intermediate-pressure discharge port 13, and the overall pressure increase in the casing 30 can be suppressed.

[0117] Further, for example, when the compressor 2 is disposed to extend in the up-down direction Dv and the other side in the O-axis direction is the lower side Dvd, the lubricant is collected in a lower part of the casing 30. Therefore, an oil surface S is positioned below an upper end of the stator 52. In the present aspect, since the intermediate-pressure discharge port 13 is positioned above the stator 52, the intermediate-pressure refrigerant can be efficiently discharged to the outside without interference from the oil surface S. Therefore, the overall pressure increase in the casing 30 can be further suppressed.

[0118] As described above, since the overall pressure increase in the casing 30 is suppressed, the increase in the pressure on the high-pressure side in the casing 30 is favorably suppressed. Therefore, it is not necessary to increase the thickness of the discharge port 12 in order to ensure the pressure resistance.

[0119] (7) In a compressor 2 according to a seventh aspect, in the compressor 2 according to the sixth aspect, the second compression portion 70 is a scroll compression portion and has a suction portion 78 that sucks the intermediate-pressure refrigerant therein, and the intermediate-pressure discharge port 13 is disposed at a circumferential position different from the suction portion 78 as viewed in the O-axis direction.Industrial Applicability

[0120] According to the compression system and the compressor of the present disclosure, a design constraint can be reduced.Reference Signs List

[0121] 1: compression system 2 compressor 3: condenser 4: expansion valve 5: evaporator 6: accumulator 7: sub-accumulator 8: valve 9: sensor 10: suction port 11: drive bush 12: discharge port 13: intermediate-pressure discharge port 20: refrigerant pipe 21: suction pipe 22: discharge pipe 23: intermediate pipe 24: bypass pipe 30: casing 31: casing main body portion 32: first lid portion 33: second lid portion 34: oil sump 40: shaft 41: shaft body 42: first eccentric shaft portion 43: second eccentric shaft portion 50: motor 51: rotor 52: stator 60: first compression portion 61: cylinder 62: separator plate 63: piston rotor 64: suction holes 65: compression chamber 70: second compression portion 71: fixed scroll 72: movable scroll 73: first end plate 74: first spiral plate 75: second end plate 76: second spiral plate 77: boss portion 78: suction portion 79: compression chamber 80: control device 81: reception unit 82: pressure determination unit 83: valve control unit 90: main bearing 91: Oldham link 1100: computer 1110: processor 1120: main memory 1130: storage 1140: interface Dv: vertical direction Dvu: upper side Dvd: lower side O axis line S: oil surface

Claims

1. A compression system comprising: a compressor that includes a casing, a first compression portion that is provided in the casing, that compresses a low-pressure refrigerant supplied from an outside to generate an intermediate-pressure refrigerant, and that discharges the intermediate-pressure refrigerant into the casing, and a second compression portion that is provided in the casing, that is set to have a smaller displacement than the first compression portion, and that further compresses the intermediate-pressure refrigerant in the casing to generate a high-pressure refrigerant; an evaporator that evaporates the refrigerant having passed through the compressor; a suction pipe that supplies the low-pressure refrigerant having passed through the evaporator into the casing; a discharge pipe that discharges the high-pressure refrigerant to an outside of the casing; a bypass pipe that returns the intermediate-pressure refrigerant in the casing to the suction pipe between the evaporator and the first compression portion; and a valve that is provided in the bypass pipe.

2. The compression system according to Claim 1, further comprising: an accumulator that is provided between the evaporator and the first compression portion on the suction pipe and that is capable of storing the refrigerant; and a sub-accumulator that is provided between the accumulator and the first compression portion on the suction pipe, that is capable of storing the refrigerant, and that has a smaller capacity than the accumulator, wherein the bypass pipe is connected between the accumulator and the sub-accumulator on the suction pipe.

3. The compression system according to Claim 1 or 2, further comprising: a control device that opens the valve to put the bypass pipe in an open state when the compressor starts an operation.

4. The compression system according to Claim 1 or 2, wherein the compressor further includes a shaft that is disposed in the casing, to which the first compression portion is connected on one side in an axial direction and to which the second compression portion is connected on the other side in the axial direction, a motor that is disposed in the casing, has a rotor provided on a radial inner side and a stator provided on a radial outer side, and that rotates the shaft, and an intermediate-pressure discharge port to which the bypass pipe is connected, and the intermediate-pressure discharge port is provided on the other side in the axial direction with respect to the stator.

5. The compression system according to Claim 4, wherein the second compression portion is a scroll compression portion and has a suction portion that sucks the intermediate-pressure refrigerant therein, and the intermediate-pressure discharge port is disposed at a circumferential position different from the suction portion as viewed in the axial direction.

6. A compressor comprising: a casing; a suction port provided in the casing; a first compression portion that is provided in the casing, that compresses a low-pressure refrigerant supplied from an outside through the suction port to generate an intermediate-pressure refrigerant, and that discharges the intermediate-pressure refrigerant into the casing; a second compression portion that is provided in the casing, that is set to have a smaller displacement than the first compression portion, and that further compresses the intermediate-pressure refrigerant in the casing to generate a high-pressure refrigerant; a discharge port that is provided in the casing and that discharges the high-pressure refrigerant to an outside of the casing; a shaft that is disposed in the casing, to which the first compression portion is connected on one side in an axial direction and to which the second compression portion is connected on the other side in the axial direction; a motor that is disposed in the casing, has a rotor provided on a radial inner side and a stator provided on a radial outer side, and that rotates the shaft; and an intermediate-pressure discharge port that discharges the intermediate-pressure refrigerant in the casing to the outside of the casing, wherein the intermediate-pressure discharge port is provided on the other side in the axial direction with respect to the stator.

7. The compressor according to Claim 6, wherein the second compression portion is a scroll compression portion and has a suction portion that sucks the intermediate-pressure refrigerant therein, and the intermediate-pressure discharge port is disposed at a circumferential position different from the suction portion as viewed in the axial direction.

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