Compression system and compressor

Abstract

To provide a compression system capable of reducing restrictions on design, and a compressor.SOLUTION: A compression system comprises: a casing: a compressor comprising a first compression unit that is provided in the casing and compresses a low-pressure refrigerant supplied from the outside to generate an intermediate-pressure refrigerant and discharging it into the casing, and a second compression unit that is provided in the casing, has a smaller displacement than the first compression unit and 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 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 provided in the bypass pipe.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses a multi-stage compression compressor having first and second rotary compression elements. In this compressor, the refrigerant compressed and discharged by the first rotary compression element is sucked into the second rotary compression element, compressed, and discharged to a gas cooler. Furthermore, this compressor is provided with a bypass circuit that supplies the refrigerant discharged from the first rotary element to an evaporator without reducing the pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-108334 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the compressor described in Patent Document 1, the intermediate pressure in the compressor increases due to the difference in the displacement between the first and second rotary compression elements at the start of operation. When the intermediate pressure increases, the high pressure on the discharge side of the second rotary compression element becomes excessively high, which requires an increase in the thickness of the piping on the high pressure side, resulting in a problem of increased design constraints.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a compression system and a compressor that can reduce design constraints. [Means for solving the problem]

[0006] In order to solve the above problems, the compression system according to the present disclosure includes a compressor including a casing, a first compression unit provided within the casing, compressing a low-pressure refrigerant supplied from an outside to generate an intermediate-pressure refrigerant and discharging it into the casing, and a second compression unit provided within the casing, having a smaller displacement than the first compression unit and further compressing the intermediate-pressure refrigerant in the casing to generate a high-pressure refrigerant, an evaporator that evaporates 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 provided in the bypass pipe.

[0007] a first compression section provided within the casing for compressing a low-pressure refrigerant supplied from outside through the suction port to generate an intermediate-pressure refrigerant and discharging the refrigerant into the casing; a second compression section provided within the casing for a smaller displacement than the first compression section and configured to further compress the intermediate-pressure refrigerant in the casing to generate a high-pressure refrigerant; a discharge port provided in the casing for discharging the high-pressure refrigerant outside the casing; a shaft provided within the casing and connected to one side in an axial direction of the first compression section and to the other side in the axial direction of the second compression section; a motor provided within the casing and having a rotor provided radially inside and a stator provided radially outside, the motor rotating the shaft; and an intermediate-pressure discharge port for discharging the intermediate-pressure refrigerant in the casing outside the casing, the intermediate-pressure discharge port being provided on the other side in the axial direction of the stator. Effect of the Invention

[0008] The compression system and compressor of the present disclosure can reduce design constraints. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a compression system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a longitudinal sectional view of a compressor according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a top view of a compressor according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a functional block diagram of a control device according to an embodiment of the present disclosure. [Diagram 5] 4 is a flow diagram showing a procedure for opening and closing a bypass pipe according to an embodiment of the present disclosure. [Figure 6] FIG. 13 is a diagram illustrating a case where a bypass pipe is in an open state according to an embodiment of the present disclosure. [Figure 7] FIG. 13 is a diagram illustrating a case where a bypass pipe is in a closed state according to an embodiment of the present disclosure. [Figure 8] FIG. 2 is a hardware configuration diagram according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Compression system configuration) Hereinafter, a compression system 1 according to an embodiment of the present disclosure will be described with reference to FIGS. A compression system 1 shown in FIG. 1 is used in, for example, an air conditioner for refrigeration and freezing. The compression system 1 compresses a refrigerant, which is a gas such as carbon dioxide. The compression system 1 includes a refrigerant pipe 20 that is a pipe for distributing and circulating the refrigerant, a compressor 2 arranged on the refrigerant pipe 20, a condenser 3, an expansion valve 4, an evaporator 5, 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. During operation of the compression system 1, the refrigerant also passes through each device in this order.

[0011] (Compressor) The compressor 2 pumps the refrigerant in the refrigerant pipe 20. As a result, the pressure and temperature of the refrigerant after passing through the compressor 2 are higher than those of the refrigerant before passing through the compressor 2. The configuration of the compressor 2 will be described in detail later.

[0012] (Condenser) The condenser 3 exchanges heat between the refrigerant that has flowed into the condenser 3 and a heat medium that is supplied from the outside.

[0013] (Expansion valve) The expansion valve 4 reduces the pressure of the refrigerant passing through the expansion valve 4, thereby rapidly reducing the temperature.

[0014] (Evaporator) The evaporator 5 evaporates the refrigerant that has passed through the compressor 2. The evaporator 5 exchanges heat between the refrigerant that has flowed into the evaporator 5 and a heat medium that is supplied from the outside. This causes the refrigerant that has flowed into the evaporator 5 to evaporate. The refrigerant that has passed through the evaporator 5 passes through the accumulator 6 and the sub-accumulator 7 in this order.

[0015] (accumulator) 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.

[0016] (Sub-accumulator) 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, similar to the accumulator 6. The capacity of the sub-accumulator 7 is smaller than the capacity of the accumulator 6. The sub-accumulator 7 is disposed at a position close to the compressor 2.

[0017] (Compressor configuration) Next, the configuration of the compressor 2 will be described. As shown in FIG. 2, in this embodiment, the compressor 2 is disposed so as to extend vertically.

[0018] Hereinafter, the vertical direction will simply be referred to as the "vertical direction Dv." The upper side will be marked with the symbol "Dvu" and the lower side will be marked with the symbol "Dvd." The compressor 2 includes a casing 30, a shaft 40, a motor 50, a suction port 10, a first compression section 60, a second compression section 70, a drive bush 11, a discharge port 12, an intermediate pressure discharge port 13, and a valve 8.

[0019] (Casing) The casing 30 has a casing main body 31, a first lid portion 32, and a second lid portion 33. The casing main body 31 is formed in a cylindrical shape and disposed so as to extend in the vertical direction Dv.

[0020] In the following description, the central axis of the casing main body 31 may be simply referred to as the "axis O". Since the axis O extends in the up-down direction Dv, one side in the direction of the axis O may be simply referred to as the lower side Dvd, and the other side in the direction of the axis O may be simply referred to as the upper side Dvu. Additionally, the radial direction about the axis O may be simply referred to as the "radial direction", and the circumferential direction about the axis O may be simply referred to as the "circumferential direction".

[0021] The first lid portion 32 closes an opening on the lower side Dvd of the casing main body 31. The second lid portion 33 closes an opening on the upper side Dvu of the casing main body 31. The casing 30 thus constructed seals the internal space. An oil reservoir 34 is formed at the bottom of the lower side Dvd of the casing 30.

[0022] (shaft) The shaft 40 is disposed so as to extend vertically inside the casing 30. The shaft 40 has 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 with the axis O as its center.

[0023] A first eccentric shaft portion 42 is provided on one side (lower side Dvd) in the direction of the axis O of the shaft main body 41. Two first eccentric shaft portions 42 are provided and arranged vertically along the direction of the axis O. The first eccentric shaft portion 42 is parallel to the axis O and has a cylindrical shape centered on an eccentric axis extending at a position radially shifted from the axis O.

[0024] Further, a second eccentric shaft portion 43 is provided on the other side (upper side Dvu) in the direction of the axis O of the shaft body 41. The second eccentric shaft portion 43 protrudes from the shaft body 41 toward the other side in the direction of the axis O. The second eccentric shaft portion 43 is parallel to the axis O and has a cylindrical shape centered on an eccentric axis extending at a position radially shifted from the axis O.

[0025] (Motor) The motor 50 is disposed within the casing 30. The motor 50 has a rotor 51 provided on the radially inner side and a stator 52 provided on the radially outer side.

[0026] (Rotor) The rotor 51 is fixed to the shaft body 41. The rotor 51 is formed in a cylindrical shape with the axis O as its center.

[0027] (Stator) The stator 52 covers the rotor 51 from the outer periphery side. The stator 52 is fixed to the inner periphery surface of the casing body 31, and is located at the middle part of the casing body 31 in the direction of the axis O. When electricity is applied to 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. This causes the shaft 40 to rotate about the axis O.

[0028] (suction port) The casing 30 is provided with a suction port 10 that introduces refrigerant from the outside into the casing 30. More specifically, the suction port 10 is provided at an end of the lower side Dvd of the casing main body 31, and protrudes radially outward from the casing main body 31.

[0029] (First compression section) The first compression section 60 is provided inside the casing 30. The first compression section 60 compresses the refrigerant supplied from the outside of the casing 30 through the suction port 10.

[0030] In the following description, the refrigerant supplied from the suction pipe 21 to the first compression section 60 may be referred to as a "low-pressure refrigerant", and the refrigerant produced by first compression section 60 compressing the low-pressure refrigerant may be referred to as an "intermediate-pressure refrigerant". Furthermore, 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".

[0031] The first compression section 60 discharges the produced intermediate-pressure refrigerant into the casing 30. The first compression section 60 is connected to an end of the shaft 40 on one side (lower side Dvd) in the axial direction O.

[0032] The first compression section 60 of the present embodiment is a so-called rotary compression section, and is disposed in the oil reservoir 34 in the casing 30. The first compression section 60 has a plurality of disk-shaped cylinders 61, a separator plate 62, and a piston rotor 63.

[0033] Two cylinders 61 are provided, arranged one above the other along the direction of the axis O. The number of cylinders 61 may be three or more, or may be one. A compression chamber 65 is formed inside each cylinder 61. The compression chamber 65 accommodates a piston rotor 63 therein.

[0034] Further, a separator plate 62 is disposed between the cylinders 61 so as to be sandwiched vertically by the cylinders 61. The separator plate 62 separates the compression chambers 65 from each other.

[0035] Each cylinder 61 is formed with a suction hole 64 that communicates with an internal compression chamber 65. The suction hole 64 allows the refrigerant supplied from the outside through the suction port 10 to flow into the inside of each cylinder 61.

[0036] The piston rotor 63 is formed in a cylindrical shape with an outer diameter smaller than the inner diameter of the cylinder 61. The piston rotor 63 is disposed inside the cylinder 61. Furthermore, 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 in association with the rotation of the shaft 40.

[0037] The first compression section 60 is provided with a discharge hole (not shown). The refrigerant compressed in the first compression section 60 (intermediate-pressure refrigerant) is discharged through the discharge hole into the internal space of the casing 30, which is set at intermediate pressure, i.e., into the space above the cylinder 61.

[0038] (Second compression section) The second compression section 70 is provided inside the casing 30. The second compression section 70 further compresses the intermediate-pressure refrigerant inside the casing 30. In the following description, the refrigerant produced by further compressing the intermediate-pressure refrigerant in the second compression section 70 may be referred to as a "high-pressure refrigerant." Also, the pressure of this high-pressure refrigerant may be referred to as a "high pressure." The second compression portion 70 is connected to the end portion of the shaft 40 on the other side (upper side Dvu) in the axis O direction.

[0039] The second compression section 70 of the present embodiment is a so-called scroll compression section, and is disposed above the motor 50 within the casing 30. The second compression section 70 has a fixed scroll 71, a movable scroll 72, and a suction section 78.

[0040] (Fixed Scroll) The fixed scroll 71 has a disk-shaped first end plate 73 centered on the axis O, and a first spiral plate 74 provided on one side in the direction of the axis O (lower side Dvd) of the first end plate 73. The first spiral plate 74 extends in a spiral shape centered on the axis O. The fixed scroll 71 is fixed to the casing body 31 via a main bearing 90.

[0041] (movable scroll) The movable scroll 72 has a disk-shaped second end plate 75, a second spiral plate 76 provided on the other side (upper side Dvu) of the second end plate 75 in the direction of the axis O, and a boss portion 77. The second spiral plate 76 extends in a spiral shape centered on the axis O. The dimension of the second spiral plate 76 in the direction of the axis O is equal to the dimension of the above-mentioned first spiral plate 74 in the direction of the axis O. In this manner, the first spiral plate 74 and the second spiral plate 76 mesh with each other from the direction of the axis O, thereby forming a compression chamber 79 between them.

[0042] The boss portion 77 is a cylindrical portion that protrudes from the second end plate 75 toward one side (lower side Dvd) in the direction of the axis O. The boss portion 77 is attached to the second eccentric shaft portion 43 of the shaft 40 via the drive bush 11. When the second eccentric shaft portion 43 rotates about the axis O, power is transmitted to the movable scroll 72 through the drive bush 11. As a result, the movement of the movable scroll 72 is restricted by the Oldham link 91, and the movable scroll 72 orbits about the axis O.

[0043] (Suction part) 3, the second compression section 70 is formed with a suction section 78 which is a hole that sucks in the intermediate-pressure refrigerant generated in the first compression section 60 and guides it into an internal compression chamber 79. The suction section 78 is formed, for example, so as to extend from the outer circumferential side of the second compression section 70 into the first end plate 73. In the illustrated example, two suction sections 78 are formed in the first end plate 73. The two suction sections 78 are disposed symmetrically about the axis O when viewed in the direction of the axis O (when viewed from above).

[0044] As the movable scroll 72 orbits, the volume of the compression chamber 79 changes over time, and the intermediate-pressure refrigerant is compressed while being sent from the outer side to the inner side in the radial direction within the compression chamber 79, thereby generating a high-pressure refrigerant. The high-pressure refrigerant generated in the second compression section 70 is discharged into the casing 30.

[0045] (Discharge port) A discharge port 12 that discharges the high-pressure refrigerant generated in the second compression section 70 to the outside of the casing 30 is provided on the other side (upper side Dvu) of the casing 30 in the direction of the axis O. More specifically, the discharge port 12 is provided in the second cover portion 33 of the casing 30 and extends from the second cover portion 33 along the direction of the axis O. The discharge port 12 communicates between the inside and the outside of the casing 30.

[0046] (Intermediate pressure exhaust port) 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) in the direction of the axis O of the casing 30. The intermediate pressure discharge port 13 is provided on the other side (upper side Dvu) in the direction of the axis O of the stator 52. In the illustrated example, the intermediate pressure discharge port 13 is provided on the other side (upper side Dvu) in the direction of the axis O of the fixed scroll 71 of the second compression section 70. The intermediate pressure discharge port 13 extends radially outward from the second cover portion 33 of the casing 30.

[0047] Furthermore, when viewed from the direction of axis O (from above), the intermediate pressure discharge port 13 is disposed at a circumferential position (phase) different from that of the suction section 78 of the second compression section 70. In the illustrated example, the intermediate pressure discharge port 13 is disposed at a position spaced apart from the suction section 78 by a phase of approximately 90 degrees about the axis O.

[0048] (Refrigerant piping) Next, the configuration of the refrigerant will be described in detail. As shown in Fig. 1, the refrigerant piping 20 has a suction pipe 21, a discharge pipe 22, an intermediate pipe 23, and a bypass pipe 24.

[0049] (Suction pipe) 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 inside of the casing 30 of the compressor 2. The suction pipe 21 is also provided with the above-mentioned accumulator 6 and sub-accumulator 7. The accumulator 6 is provided on the suction pipe 21 between the evaporator 5 and the first compression section 60, and the sub-accumulator 7 is provided on the suction pipe 21 between the accumulator 6 and the first compression section 60.

[0050] (discharge pipe) 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.

[0051] (Intermediate piping) 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 intermediate pipe 23 is provided with an expansion valve 4.

[0052] (Bypass pipe) 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 this embodiment, the bypass pipe 24 is connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21.

[0053] (valve) The bypass pipe 24 is provided with a valve 8 that opens and closes the bypass pipe 24. The valve 8 is a so-called electromagnetic valve, and is controlled by a control device 80, which will be described later.

[0054] (Sensor) The sensor 9 detects the 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 section 60, and transmits the pressure to the control device 80.

[0055] (Control device) The control device 80 controls each device constituting the compression system 1 described above. As shown in FIG. 4, the control device 80 has various functional units, such as a receiving unit 81, a pressure determining unit 82, and a valve control unit 83. The receiving unit 81 receives information including the pressure value of the low-pressure refrigerant flowing through the suction pipe 21, which is transmitted from the sensor 9. The pressure determination unit 82 determines whether the pressure detected by the sensor 9 (the pressure of the refrigerant flowing through the suction pipe 21) is equal to or lower than a threshold value. 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 open the bypass pipe 24 when the compressor 2 starts operating, and closes the valve 8 to open the bypass pipe 24 when the compressor 2 enters a steady operation.

[0056] (Bypass pipe opening and closing procedure) The bypass pipe 24 is opened and closed at the start of operation of the compression system 1. The procedure for opening and closing the bypass pipe 24 will be described with reference to the flow chart of FIG. First, before the compression system 1 starts operating, the valve control unit 83 opens the valve 8 and opens the bypass pipe 24 (step S10). In this state, the compression system 1 operates. Then, as shown in Fig. 6, the refrigerant flows through the refrigerant pipe 20 and starts circulating in the cooling system. In the following, the refrigerant pipe 20 in the open state is illustrated by a solid line, and the refrigerant pipe 20 in the closed state is illustrated by a dashed line. Furthermore, the direction of the refrigerant flow is illustrated by an arrow.

[0057] Since the bypass pipe 24 is in an open state, the pressure difference between the inside of the casing 30 and the inside of the suction pipe 21 is almost eliminated, and the compression by the first compression section 60 is cancelled. In other words, the first compression section 60 can be considered to be not performing work. Usually, immediately after the start of operation, the pressure in the casing 30 rises suddenly, and there is a risk that the pressure on the high-pressure side in the casing 30 exceeds the limit pressure (design pressure) of the discharge pipe 22, so that a complex operation control is required. However, in this embodiment, by opening the bypass pipe 24, the boost pressure is reduced, and a sudden pressure rise in the casing 30 is suppressed, and the pressure in the casing 30 can be made equal to or lower than the limit pressure of the discharge pipe 22.

[0058] 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 section 60 flows, and transmits information including the pressure of the suction pipe 21 to the control device 80. The pressure detection and information transmission by the sensor 9 are performed periodically, for example, at regular time intervals. Then, the receiving unit 81 of the control device 80 receives the transmitted pressure of the suction pipe 21 (step S11).

[0059] After step S11, the pressure determination unit 82 determines whether the pressure in the suction pipe 21 is equal to or lower than a preset threshold value (step S12). If the pressure in the suction pipe 21 is not equal to or lower than the threshold value (step S12; NO), the process returns to step S11. If the pressure in the suction pipe 21 is equal to or lower than the threshold value (step S12; YES), the valve control unit 83 closes the valve 8, and closes the bypass pipe 24 as shown in FIG. 7 (step S13).

[0060] Here, there is a correlation between the pressure in the suction pipe 21 (low pressure of the low-pressure refrigerant), the pressure in the casing 30 (intermediate pressure of the intermediate-pressure refrigerant), and the pressure in 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. This preset threshold is a low pressure value whose upper limit of the high pressure becomes the limit pressure of the discharge pipe 22 when the bypass pipe 24 is in a closed state. When the pressure in the suction pipe 21 is a value lower than this threshold (step S12; YES), the high pressure becomes equal to or lower than the limit pressure, and the compression system 1 can operate stably (steady operation).

[0061] In step S13, when the low pressure falls below this threshold value, the bypass pipe 24 is closed, so that the high pressure does not exceed the limit pressure and a safe transition to steady operation can be made. In this manner, the bypass pipe 24 is opened and closed.

[0062] (Action and effect) The compression system 1 and the compressor 2 of the present embodiment can achieve the following advantageous effects.

[0063] In this 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 section 60. The valve 8 is provided in the bypass pipe 24.

[0064] As a result, by opening the valve 8 and opening the bypass pipe 24, the intermediate-pressure refrigerant in the casing 30 can be released to the suction pipe 21. Furthermore, 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 rise in the casing 30 can be suppressed. Therefore, since the pressure rise 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 thicken the discharge pipe 22 in order to ensure the pressure resistance of the discharge pipe 22. Therefore, design constraints can be alleviated.

[0065] As described above, the bypass pipe 24 is provided to guide the intermediate-pressure refrigerant directly to the suction pipe 21 without passing through the condenser 3, so that the intermediate-pressure refrigerant bypassed from inside the casing 30 is returned to a position on the suction pipe 21 close to the first compression section 60. This makes it possible to reduce the pressure loss of the intermediate-pressure refrigerant flowing through the bypass pipe 24.

[0066] In this embodiment, the bypass pipe 24 is connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21 .

[0067] The sub-accumulator 7 prevents the low-pressure refrigerant from flowing back from the first compression section 60. In addition, since the sub-accumulator 7 has a smaller capacity than the accumulator 6, the installation location can be freely selected compared to the accumulator 6. Therefore, the sub-accumulator 7 can be disposed in a position close to the first compression section 60. Furthermore, in this 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 this embodiment can reduce pressure loss by returning the intermediate-pressure refrigerant bypassed from inside the casing 30 to a position close to the first compression section 60 while preventing the low-pressure refrigerant from flowing back.

[0068] In this embodiment, the compression system 1 further includes a control device 80 that opens the valve 8 to open the bypass pipe 24 when the compressor 2 starts operating.

[0069] Usually, at the start of operation, the intermediate pressure in the casing 30 rises suddenly due to the difference in the displacement between the first compression section 60 and the second compression section 70, and there is a risk that the pressure on the high-pressure side (the pressure in the discharge pipe 22) will exceed the limit pressure, requiring complex operation control. In this embodiment, when the compressor 2 starts operation, the valve 8 is opened to open the bypass pipe 24, so that the intermediate pressure in the casing 30 is released to the suction pipe 21. This reduces the pressure difference between the low-pressure side and the intermediate-pressure side in the casing 30, and the overall pressure rise in the casing 30 can be suppressed. Therefore, the pressure rise on the high-pressure side in the casing 30 can be suppressed at the start of operation, when the pressure rise is likely to increase.

[0070] Furthermore, when the compressor 2 enters a steady operation state, the control device 80 closes the valve 8 to close the bypass pipe 24 .

[0071] The pressure of the compressor 2 becomes stable after a predetermined time has elapsed (steady operation). In steady operation, the pressure in the discharge pipe 22 becomes stable at a state lower than the limit pressure, so there is no need to release the intermediate pressure in the casing 30 through the bypass pipe 24. When the compressor 2 enters steady operation, the control device 80 closes the valve 8 to close the bypass pipe 24. In this embodiment, the control device 80 determines that the compressor 2 has transitioned to a steady operation when the pressure in the suction pipe 21 detected by the sensor 9 falls below a preset threshold value, and closes the valve 8, but this is not limited to the above. For example, the control device 80 may determine that the compressor 2 has transitioned to a steady operation when a predetermined time has elapsed since the compressor 2 started operating, and close the valve 8.

[0072] In this embodiment, the compressor 2 discharges the intermediate pressure refrigerant in the casing 30 to the outside of the casing 30. The compressor 2 is provided with an intermediate pressure discharge port 13. A 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 direction of the axis O.

[0073] This allows the intermediate-pressure refrigerant to escape to the outside through the intermediate-pressure discharge port 13, making it possible to suppress an overall pressure increase within the casing 30.

[0074] For example, when the compressor 2 is disposed to extend in the vertical direction Dv and the other side in the direction of the axis O is the upper side Dvu as in this embodiment, the lubricating oil accumulates in the lower part of the casing 30. Therefore, the oil level S is located below the upper end of the stator 52. In this embodiment, the intermediate pressure discharge port 13 is located above the stator 52, so that the intermediate pressure refrigerant can be efficiently discharged to the outside without interference from the oil level S. Therefore, the overall pressure rise inside the casing 30 can be further suppressed. In this way, the overall pressure increase inside the casing 30 is suppressed, and therefore the pressure increase on the high pressure side inside the casing 30 is effectively suppressed. Therefore, it is no longer necessary to increase the thickness of the discharge port 12 in order to ensure pressure resistance.

[0075] Furthermore, in the compression system 1 as a whole, since the bypass pipe 24 is connected to the intermediate pressure discharge port 13, the bypass pipe 24 is located above the upper end of the stator 52. Therefore, the intermediate pressure refrigerant can be returned to the suction pipe 21 without being interfered with by the oil level S. Therefore, the compression system 1 can return the intermediate pressure refrigerant to the suction pipe 21 efficiently.

[0076] In this embodiment, the second compression section 70 is a scroll compression section, and has a suction section 78 that draws the intermediate-pressure refrigerant therein. The intermediate-pressure discharge port 13 is disposed at a circumferential position different from the suction section 78 when viewed from the axis O direction.

[0077] This allows the intermediate pressure discharge port 13 and the suction portion 78 to be disposed apart from each other. This prevents most of the intermediate pressure refrigerant from being sucked into the suction portion 78 before being supplied to the intermediate pressure discharge port 13. This allows the intermediate pressure refrigerant to be efficiently guided to the intermediate pressure discharge port 13, and allows a sufficient amount of intermediate pressure refrigerant to be bypassed through the bypass pipe 24 to reduce the pressure inside the casing 30.

[0078] In this 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 direction of the axis O relative to the fixed scroll 71 of the second compression section 70.

[0079] This allows the intermediate-pressure refrigerant to be supplied from the first compression section 60 to the second compression section 70 without impeding the flow of the refrigerant.

[0080] (Hardware configuration) The control device 80 of the above-described embodiments is implemented in a computer as shown in Fig. 8. Fig. 8 is a schematic block diagram showing an example of a configuration of a computer in which the control device 80 according to each embodiment is implemented. The computer 1100 includes a processor 1110, a main memory 1120, a storage 1130, and an interface 1140.

[0081] The operation of each functional unit of the control device 80 is stored in the form of a program in the storage 1130. The processor 1110 reads the program from the storage 1130, loads it in the main memory 1120, and executes the above-mentioned processing in accordance with the program. The processor 1110 also secures a storage area in the main memory 1120 in accordance with the program.

[0082] The program may be for realizing a part of the functions to be performed by the computer 1100. For example, the program may be for realizing the functions by combining with other programs already stored in the storage 1130 or by combining with other programs implemented in other devices. The computer 1100 may also include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions to be realized by the processor 1110 may be realized by the integrated circuit.

[0083] Examples of storage 1130 include a magnetic disk, a magneto-optical disk, and a semiconductor memory. Storage 1130 may be an internal medium directly connected to the bus of computer 1100, or an external medium connected to computer 1100 via interface 1140 or a communication line. In addition, when this program is distributed to computer 1100 via a communication line, computer 1100 that receives the program may load the program in main memory 1120 and execute the above-mentioned processing. Storage 1130 may be a non-transitory tangible storage medium.

[0084] The program may be for realizing part of the above-mentioned functions. Furthermore, the program may be a so-called difference file (difference program) that realizes the above-mentioned functions in combination with other programs already stored in the storage 1130.

[0085] (Other embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of the present disclosure are also included.

[0086] In the above embodiment, the first compression section 60 is a rotary compression section and the second compression section 70 is a scroll compression section, but this is not limited thereto. For example, the first compression section 60 may be a scroll compression section and the second compression section 70 may be a rotary compression section. In addition, both the first compression section 60 and the second compression section 70 may be rotary compression sections. In addition, both the first compression section 60 and the second compression section 70 may be scroll compression sections.

[0087] In the above 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 direction of the axis O relative to the fixed scroll 71 of the second compression section 70, but is not limited to this. The intermediate pressure discharge port 13 may be provided between the stator 52 and the suction section 78 of the second compression section 70. In this case, before the intermediate pressure refrigerant is sucked into the suction section 78, the intermediate pressure refrigerant can be guided to the intermediate pressure discharge port 13 at each nozzle and bypassed to the suction pipe 21 through the bypass pipe 24.

[0088] <Additional Notes> The compression system 1 and the compressor 2 described in each embodiment can be understood, for example, as follows.

[0089] (1) A compression system 1 according to a first aspect includes a compressor 2 including a casing 30, a first compression section 60 provided within the casing 30, compressing a low-pressure refrigerant supplied from an outside to generate an intermediate-pressure refrigerant and discharging the refrigerant into the casing 30, and a second compression section 70 provided within the casing 30, having a smaller displacement than the first compression section 60 and further compressing the intermediate-pressure refrigerant in the casing 30 to generate a high-pressure refrigerant, an evaporator 5 that evaporates refrigerant that has passed through the compressor 2, a suction pipe 21 that supplies the low-pressure refrigerant that has passed through the evaporator 5 into the casing 30, a discharge pipe 22 that discharges the high-pressure refrigerant to the 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 section 60, and a valve 8 provided in the bypass pipe 24.

[0090] As a result, by opening the valve 8 and opening the bypass pipe 24, the intermediate-pressure refrigerant in the casing 30 can be released to the suction pipe 21. Furthermore, 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 an overall pressure increase in the casing 30 can be suppressed. As a result, a pressure increase on the high-pressure side in the casing 30 is suppressed, and 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. As a result, it is not necessary to thicken the discharge pipe 22 in order to ensure the pressure resistance of the discharge pipe 22.

[0091] (2) The compression system 1 of the second aspect is the compression system 1 of the first aspect, further comprising an accumulator 6 that is provided on the suction pipe 21 between the evaporator 5 and the first compression section 60 and is capable of storing a refrigerant, and a sub-accumulator 7 that is provided on the suction pipe 21 between the accumulator 6 and the first compression section 60 and is capable of storing a refrigerant and has a smaller capacity than the accumulator 6, and the bypass pipe 24 may be connected between the accumulator 6 and the sub-accumulator 7 on the suction pipe 21.

[0092] The sub-accumulator 7 prevents the low-pressure refrigerant from flowing back from the first compression section 60. In addition, since the sub-accumulator 7 has a smaller capacity than the accumulator 6, the installation location can be freely selected compared to the accumulator 6. Therefore, the sub-accumulator 7 can be disposed at a position close to the first compression section 60. Furthermore, in this 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 this embodiment can return the intermediate-pressure refrigerant bypassed from inside the casing 30 to a position close to the first compression section 60, thereby reducing pressure loss.

[0093] (3) The compression system 1 of a third aspect may be the compression system 1 of the first or second aspect, further including a control device 80 that opens the valve 8 to open the bypass pipe 24 when the compressor 2 starts operation.

[0094] Usually, at the start of operation, the intermediate pressure in the casing 30 rises suddenly due to the difference in the displacement between the first compression section 60 and the second compression section 70, and there is a risk that the pressure on the high-pressure side (the pressure in the discharge pipe 22) will exceed the limit pressure, requiring complex operation control. In this embodiment, when the compressor 2 starts operation, the valve 8 is opened to open the bypass pipe 24, so that the intermediate pressure in the casing 30 is released to the suction pipe 21. This reduces the pressure difference between the low-pressure side and the intermediate-pressure side in the casing 30, and the overall pressure rise in the casing 30 can be suppressed. Therefore, the pressure rise on the high-pressure side in the casing 30 can be suppressed at the start of operation, when the pressure rise is likely to increase.

[0095] (4) A compression system 1 of a fourth aspect is the compression system 1 of any one of the first to third aspects, wherein the compressor 2 is disposed within the casing 30, and includes a shaft 40 to which the first compression section 60 is connected on one side in the axial O direction and the second compression section 70 is connected on the other side in the axial O direction, a motor 50 disposed within the casing 30 and having a rotor 51 provided radially inside and a stator 52 provided radially outside, and rotating 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 may be provided on the other side in the axial O direction of the stator 52.

[0096] For example, when the compressor 2 is disposed to extend in the vertical direction Dv and the other side in the direction of the axis O is the upper side Dvu, the lubricating oil accumulates in the lower part of the casing 30. Therefore, the oil level S is located below the upper end of the stator 52. In this embodiment, the intermediate pressure discharge port 13 is located above the stator 52, so that the intermediate pressure refrigerant can be returned to the suction pipe 21 without interference from the oil level S.

[0097] (5) A fifth aspect of the compression system 1 is the compression system 1 of the fourth aspect, wherein the second compression section 70 is a scroll compression section and has an intake section 78 that draws in intermediate-pressure refrigerant therein, and the intermediate-pressure discharge port 13 may be arranged at a circumferential position different from the intake section 78 when viewed from the direction of the axis O.

[0098] This allows the intermediate pressure discharge port 13 to be spaced apart from the suction portion 78. This prevents most of the intermediate pressure refrigerant from being sucked into the suction portion 78 before being supplied to the intermediate pressure discharge port 13.

[0099] (6) The compressor 2 of the sixth aspect includes a casing 30, a suction port 10 provided in the casing 30, a first compression section 60 provided in the casing 30, compressing a low-pressure refrigerant supplied from the outside through the suction port 10 to generate an intermediate-pressure refrigerant and discharging the refrigerant into the casing 30, a second compression section 70 provided in the casing 30, having a smaller displacement than the first compression section 60 and further compressing the intermediate-pressure refrigerant in the casing 30 to generate a high-pressure refrigerant, and a discharge section provided in the casing 30 to discharge the high-pressure refrigerant to the outside of the casing 30. the first compression section 60 is connected to one side of the casing 30 in the direction of the axis O and the second compression section 70 is connected to the other side of the casing 30 in the direction of the axis O; a motor 50 that is arranged in the casing 30 and has a rotor 51 provided radially inside and a stator 52 provided radially outside, and 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, the intermediate pressure discharge port 13 being provided on the other side of the axial O direction of the stator 52.

[0100] This allows the intermediate-pressure refrigerant to escape to the outside through the intermediate-pressure discharge port 13, making it possible to suppress an overall pressure increase within the casing 30. Furthermore, for example, when the compressor 2 is disposed to extend in the vertical direction Dv and the other side in the direction of the axis O is the lower side Dvd, the lubricating oil accumulates in the lower part of the casing 30. Therefore, the oil level S is located below the upper end of the stator 52. In this embodiment, since the intermediate pressure discharge port 13 is located above the stator 52, the intermediate pressure refrigerant can be efficiently discharged to the outside without interference from the oil level S. Therefore, the overall pressure rise inside the casing 30 can be further suppressed. In this way, the overall pressure increase inside the casing 30 is suppressed, and therefore the pressure increase on the high pressure side inside the casing 30 is effectively suppressed. Therefore, it is no longer necessary to increase the thickness of the discharge port 12 in order to ensure pressure resistance.

[0101] (7) The compressor 2 of a seventh aspect is the compressor 2 of the sixth aspect, wherein the second compression section 70 is a scroll compression section and has an intake section 78 that draws in intermediate-pressure refrigerant therein, and the intermediate-pressure discharge port 13 may be arranged at a circumferential position different from the intake section 78 when viewed from the direction of the axis O. [Explanation of symbols]

[0102] 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 piping 21...Suction pipe 22...Discharge pipe 23...Intermediate pipe 24...Bypass pipe 30...Casing 31...Casing body 32...First cover 33...Second cover 34...Oil reservoir 40...Shaft 41...Shaft body 42...First eccentric shaft 43...Second eccentric shaft 50...Motor 51...Rotor 52...Stator 60...First compression section 61...Cylinder 62...Separator plate 63...Piston rotor 64...Suction hole 65...Compression chamber 70...Second compression section 71...Fixed scroll 72...Moving 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...Receiver portion 82...Pressure determination portion 83...Valve control portion 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 S...Oil level

Claims

1. a compressor including: a casing; a first compression section provided within the casing, compressing a low-pressure refrigerant supplied from an outside to generate an intermediate-pressure refrigerant and discharging the refrigerant into the casing; and a second compression section provided within the casing, having a smaller displacement than the first compression section and further compressing 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 for discharging 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 section; a valve provided in the bypass pipe; A compression system comprising:

2. an accumulator provided on the suction pipe between the evaporator and the first compression section, the accumulator being capable of storing a refrigerant; a sub-accumulator that is provided on the suction pipe between the accumulator and the first compression section, the sub-accumulator being capable of storing a refrigerant and having a smaller capacity than the accumulator; Further equipped with The compression system of claim 1 , wherein the bypass line is connected on the suction line between the accumulator and the subaccumulator.

3. The compression system according to claim 1 or 2, further comprising a control device that opens the valve to open the bypass pipe when the compressor starts operating.

4. The compressor includes: a shaft disposed within the casing, the shaft having one side in an axial direction connected to the first compression portion and the other side in the axial direction connected to the second compression portion; a motor disposed within the casing and having a rotor disposed radially inward and a stator disposed radially outward, the motor rotating the shaft; an intermediate pressure discharge port to which the bypass pipe is connected; Further equipped with The compression system according to claim 1 or 2, wherein the intermediate pressure discharge port is provided on the other side of the stator in the axial direction.

5. The second compression section is a scroll compression section and has a suction section that draws an intermediate-pressure refrigerant therein, The compression system according to claim 4 , wherein the intermediate pressure discharge port is disposed at a different circumferential position from the intake port when viewed from the axial direction.

6. A casing; an intake port provided in the casing; a first compression section provided within the casing, compressing a low-pressure refrigerant supplied from the outside through the suction port to generate an intermediate-pressure refrigerant and discharging the intermediate-pressure refrigerant into the casing; a second compression section provided within the casing, the second compression section having a smaller displacement than the first compression section, and configured to further compress the intermediate-pressure refrigerant within the casing to generate a high-pressure refrigerant; a discharge port provided in the casing for discharging the high-pressure refrigerant to the outside of the casing; a shaft disposed within the casing, the shaft having one side in an axial direction connected to the first compression portion and the other side in the axial direction connected to the second compression portion; a motor disposed within the casing and having a rotor disposed radially inward and a stator disposed radially outward, the motor rotating the shaft; an intermediate pressure discharge port that discharges the intermediate pressure refrigerant in the casing to the outside of the casing; Equipped with The intermediate pressure discharge port is provided on the other side of the stator in the axial direction.

7. The second compression section is a scroll compression section and has a suction section that draws an intermediate-pressure refrigerant therein, The compressor according to claim 6 , wherein the intermediate pressure discharge port is disposed at a circumferential position different from that of the suction port when viewed from the axial direction.

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