Double-section refrigerant compressor and operation method thereof

Abstract

The invention provides a double-section refrigerant compressor and an operation method thereof.The double-section refrigerant compressor comprises a shell, a first compressor module, a second compressor module, a capacity adjusting mechanism, an intermediate pressure sensor and a processor, and a motor chamber is arranged in the shell; the first compressor module comprises a first screw rod and a first motor which is accommodated in the motor chamber and drives the first screw rod to rotate; the second compressor module comprises a second screw rod and a second motor which is accommodated in the motor chamber and drives the second screw rod to rotate; the capacity adjusting mechanism comprises a first slide valve and a second slide valve; the middle pressure sensor is accommodated in the motor chamber to obtain the current middle pressure; the processor is used for receiving current medium pressure data, controlling the rotating speed of the first motor and the second motor and controlling the positions of the first sliding valve and the second sliding valve.

Description

Technical Field

[0001] The present invention relates to a compressor device, and in particular to a two-stage refrigerant compressor and an operating method thereof. Background Art

[0002] A conventional two-stage refrigerant compressor has a first compression chamber in the first shell containing a first-stage rotor, a second compression chamber in the second shell containing a second-stage rotor, and an external pipeline connecting the first compression chamber and the second compression chamber. The fluid (such as refrigerant, coolant, etc.) is compressed successively by the first and second-stage rotors, and the first compression chamber, the external pipeline and the second compression chamber are connected in sequence, so that the fluid pressures in the first compression chamber, the intermediate chamber and the second compression chamber are low pressure, medium pressure and high pressure respectively.

[0003] However, the structure of the external pipeline will affect the exhaust pressure drop of the first rotor, and the medium pressure of the external pipeline is related to the exhaust pressure / exhaust volume of the first rotor and the suction pressure / intake volume of the second rotor and interacts with each other. However, under different application conditions, the exhaust pressure / exhaust volume of the first rotor and the suction pressure / intake volume of the second rotor of the two-stage refrigerant compressor will be different. Therefore, if the medium pressure of the external pipeline, the exhaust pressure / exhaust volume of the first rotor and the suction pressure / intake volume of the second rotor are all added to the adjustable and controllable scope, the two-stage refrigerant compressor will operate in the best efficiency mode.

[0004] In view of this, the present invention provides a two-stage refrigerant compressor and an operating method thereof for the above-mentioned prior art to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0005] The present invention provides a two-stage refrigerant compressor and an operating method thereof, which utilizes a single shell to put all factors affecting energy efficiency into a controllable range, so that the two-stage spiral compressor operates in a mode with the best efficiency.

[0006] In an embodiment of the present invention, the present invention provides a two-stage refrigerant compressor, comprising: a shell, the internal partition of which is a suction passage, a first compression chamber, a motor chamber, a second compression chamber and an exhaust passage that are sequentially connected; a first compressor module, comprising a pair of first screws accommodated in the first compression chamber and meshed with each other, and a first motor accommodated in the motor chamber and driving one of the first screws to rotate, the pair of first screws defining a first contact line; a second compressor module, comprising a pair of second screws accommodated in the second compression chamber and meshed with each other, and a first motor accommodated in the motor chamber and driving one of the second screws to rotate. Two motors, the pair of second screws define a second contact line; a capacity adjustment mechanism, including a first slide valve movably arranged corresponding to the first contact line and a second slide valve movably arranged corresponding to the second contact line; a pressure sensing group, including an intermediate pressure sensor, the intermediate pressure sensor is accommodated in the motor room to obtain a current medium pressure; and a processor, connected to the first motor, the second motor, the first slide valve, the second slide valve and the intermediate pressure sensor, the processor is used to receive the data of the current medium pressure, control the rotation speed of the first motor and the second motor and control the position of the first slide valve and the second slide valve.

[0007] In an embodiment of the present invention, the present invention provides an operating method for a two-stage refrigerant compressor, the steps of which include: a) providing a two-stage refrigerant compressor as described above, wherein the first motor drives one of the first screws to rotate with variable frequency, and the second motor drives one of the second screws to rotate with variable frequency; b) obtaining a current temperature and setting a preset temperature, and the controller adjusts or maintains the speed of the first motor according to the value of the current temperature minus the preset temperature; c) calculating a set medium pressure, and the controller adjusts or maintains the speed of the second motor according to the value of the current medium pressure minus the set medium pressure; and d) calculating a low-pressure specific volume of the first compression chamber, a medium-pressure specific volume of the motor chamber, and a high-pressure specific volume of the second compression chamber, and the controller adjusts or maintains the position of the first slide valve according to the value of the low-pressure specific volume divided by the medium-pressure specific volume, and the controller adjusts or maintains the position of the second slide valve according to the value of the medium-pressure specific volume divided by the high-pressure specific volume.

[0008] In an embodiment of the present invention, the present invention provides an operating method for a two-stage refrigerant compressor, the steps of which include: e) providing a two-stage refrigerant compressor as described above, wherein the first motor drives one of the first screws to rotate at a fixed frequency, and the second motor drives one of the second screws to rotate at a variable frequency; f) obtaining a current temperature and setting a preset temperature, and the controller adjusts or maintains the position of the first slide valve according to the value of the current temperature minus the preset temperature; g) calculating a set medium pressure, and the controller adjusts or maintains the speed of the second motor according to the value of the current medium pressure minus the set medium pressure; and h) calculating a low-pressure specific volume of the first compression chamber, a medium-pressure specific volume of the motor chamber, and a high-pressure specific volume of the second compression chamber, and the controller adjusts or maintains the position of the first slide valve according to the value of the low-pressure specific volume divided by the medium-pressure specific volume, and the controller adjusts or maintains the position of the second slide valve according to the value of the medium-pressure specific volume divided by the high-pressure specific volume.

[0009] Based on the above, the present invention achieves an adjustable compression ratio by controlling the rotation speed of the first screw and the rotation speed of the second screw, and achieves an adjustable volume ratio by controlling the position of the first slide valve and the position of the second slide valve, so that all factors affecting the energy efficiency of the two-stage refrigerant compressor are included in the controllable category, allowing the two-stage spiral compressor to operate in the optimal efficiency mode under variable working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional schematic diagram of a first embodiment of a two-stage refrigerant compressor of the present invention;

[0011] Figure 2 It is a cross-sectional schematic diagram of a second embodiment of a two-stage refrigerant compressor of the present invention;

[0012] Figure 3 It is a cross-sectional schematic diagram of a third embodiment of a two-stage refrigerant compressor of the present invention;

[0013] Figure 4 It is a schematic diagram of the positions of the first (second) screw and the first (second) slide valve of the present invention;

[0014] Figure 5 A flowchart of the steps of the first embodiment of the operating method of the two-stage refrigerant compressor of the present invention;

[0015] Figure 6 A flow chart of a first embodiment of the operating method of a two-stage refrigerant compressor of the present invention;

[0016] Figure 7 A flow chart of a second embodiment of the operating method of a two-stage refrigerant compressor of the present invention;

[0017] Figure 8 A flowchart of the steps of a second embodiment of the operating method of a two-stage refrigerant compressor of the present invention;

[0018] Fig. 9 A flow chart of a third embodiment of the operating method of a two-stage refrigerant compressor of the present invention;

[0019] Fig.10 A flow chart of a fourth embodiment of the operating method of a two-stage refrigerant compressor of the present invention;

[0020] Wherein, the reference numerals are:

[0021] 10: Two-stage refrigerant compressor

[0022] 1: Shell

[0023] 11: Inhalation channel

[0024] 12: First compression chamber

[0025] 13: Motor room

[0026] 131: First Motor Room

[0027] 132: Second Motor Room

[0028] 133: Connection channel

[0029] 134: First Motor Area

[0030] 135: Second motor area

[0031] 14: Second compression chamber

[0032] 15: Exhaust channel

[0033] 16: First coolant injection port

[0034] 17: Second coolant injection port

[0035] 2: First compressor module

[0036] 21: First screw

[0037] 211: Suction end

[0038] 212: Discharge end

[0039] 22: First Motor

[0040] 3: Second compressor module

[0041] 31: Second screw

[0042] 32: Second motor

[0043] 4: Capacity adjustment mechanism

[0044] 41: First slide valve

[0045] 42: Second slide valve

[0046] 5: Pressure sensing group

[0047] 51: Intermediate pressure sensor 52: Intake pressure sensor 53: Exhaust pressure sensor C1: First error value

[0048] C2: Second error value

[0049] C3: The third error value

[0050] C4: fourth error value k1: first empirical coefficient k2: second empirical coefficient k3: third empirical coefficient k4: fourth empirical coefficient k5: fifth empirical coefficient L1: first contact line

[0051] L2: Second contact line

[0052] P1: Current medium pressure

[0053] P2: Set medium pressure

[0054] Psuc: Suction pressure Pdi s: Exhaust pressure

[0055] T1: Current temperature

[0056] T2: Preset temperature

[0057] V1: Low pressure specific volume

[0058] V2: Medium pressure specific volume

[0059] V3: High pressure specific volume

[0060] Steps a to h. DETAILED DESCRIPTION

[0061] In this specification, many specific details are provided to provide a thorough understanding of the specific embodiments of the present invention; however, those skilled in the art should know that the present invention can still be practiced without one or more of these specific details; in other cases, well-known details are not shown or described to avoid obscuring the main technical features of the present invention. The technical content and detailed description of the present invention are described as follows with the accompanying drawings:

[0062] Please refer to Figures 1 to 10 As shown, the present invention provides a two-stage refrigerant compressor and an operating method thereof. The two-stage refrigerant compressor 10 mainly includes a housing 1, a first compressor module 2, a second compressor module 3, a capacity adjustment mechanism 4, a pressure sensing group 5 and a processor.

[0063] like Figures 1 to 3As shown, the housing 1 is internally divided into an air intake passage 11, a first compression chamber 12, a motor chamber 13, a second compression chamber 14 and an air discharge passage 15 which are sequentially connected.

[0064] like Figures 1 to 3 As shown, the first compressor module 2 includes a pair of first screws 21 and a first motor 22. The pair of first screws 21 are accommodated in the first compression chamber 12 and mesh with each other. The first motor 22 is accommodated in the motor chamber 13 and drives one of the first screws 21 to rotate. A first contact line L1 is defined between the male spiral tooth surface and the female spiral tooth surface of the meshing first screws 21.

[0065] In addition, the two ends of the pair of first screws 21 have a suction end 211 and a discharge end 212 . The suction end 211 is disposed closer to the suction channel 11 than the discharge end 212 .

[0066] like Figures 1 to 3 As shown, the second compressor module 3 includes a pair of second screws 31 and a second motor 32. The pair of second screws 31 are accommodated in the second compression chamber 14 and meshed with each other. The second motor 32 is accommodated in the motor chamber 13 and drives one of the second screws 31 to rotate. A second contact line L2 is defined between the male spiral tooth surface and the female spiral tooth surface of the meshing second screws 31.

[0067] The first motor 22 directly drives the first screw 21 to rotate, and the second motor 32 directly drives the second screw 31 to rotate, so that the rotation speeds of the first screw 21 and the second screw 31 can be controlled separately between the first compressor module 2 and the second compressor module 3 without the need for a gear assembly.

[0068] In addition, the two-stage refrigerant compressor 10 is used to increase the pressure of fluids such as refrigerants and coolants (not shown) from low pressure to high pressure. The fluid starts from the intake channel 11 and passes through the first compression chamber 12, the suction end 211 of the first screw 21, the discharge end 212 of the first screw 21, the motor room 13, the first motor 22, the second motor 32, the second compression chamber 14, the second screw 31 in sequence, and is finally discharged from the exhaust channel 15. Since the fluid is compressed by the first screw 21 and the second screw 31 in turn, the fluid pressures in the first compression chamber 12, the motor room 13 and the second compression chamber 14 are low pressure, medium pressure and high pressure respectively.

[0069] Furthermore, the first motor 22 and the second motor 32 of the two-stage refrigerant compressor 10 may be disposed in a single motor chamber 13 (eg Figure 1 or Figure 3 ), or according to different design requirements, the first motor 22 and the second motor 32 are respectively set (for example Figure 2 ), and then use the connecting channel 133 to connect the two.

[0070] In addition, a fluid with a cooling function (such as a low-temperature refrigerant, sprayed by an economizer) can be injected into the motor chamber 13, and along with the working fluid (such as the refrigerant), the first motor 22 and the second motor 32 are cooled in sequence, and finally discharged through the exhaust passage 15 of the second compression chamber 14, thereby preventing the heat generated by the operation of the first motor 22 and the second motor 32 from affecting the refrigeration performance of the two-stage refrigerant compressor 10.

[0071] like Figures 1 to 3 As shown, the shell 1 is provided with a first coolant injection port 16 configured and connected between the first compression chamber 12 and the first motor chamber 131, and the first coolant (e.g., low-temperature refrigerant) is injected between the first compression chamber 12 and the first motor chamber 131 through the first coolant injection port 16, and cools the first motor 22 along with the working fluid (e.g., refrigerant); and / or the shell 1 is provided with a second coolant injection port 17 connected to the second motor chamber 132 and corresponding to the second motor 32, and the second coolant (e.g., low-temperature refrigerant) is injected into the second motor chamber 132 through the second coolant injection port 17, and cools the second motor 32 along with the working fluid (e.g., refrigerant).

[0072] Among them, Figure 1 to Figure 2 As shown, the second coolant injection port 17 is vertically connected to the second motor chamber 132 (in Figure 1 The second coolant is disposed at an end of the second motor 32 away from the second screw 31 (based on the long axis direction of the second screw 31). After the second coolant is discharged from the second coolant injection port 17, the second coolant flows toward the second motor 32 in a vertical or oblique manner.

[0073] Or, if Figure 3 As shown, the second coolant injection port 17 is connected to the second motor area 135 in parallel (in Figure 1 The second coolant is disposed at an end of the second motor 32 away from the second screw 31 (based on the long axis direction of the second screw 31). After the second coolant is discharged from the second coolant injection port 17, the second coolant flows toward the second motor 32 (or the first motor area 134 and the second motor area 135) in a parallel manner.

[0074] In actual use, the second coolant injection port 17 can be set to flow vertically, obliquely or parallel to the second motor 32 according to different working conditions. In addition, when the second motor chamber 132 (or the second motor area 135) is set below the first motor chamber 131 (or the first motor area 134), or when the first motor chamber 131 (or the first motor area 134) and the second motor chamber 132 (or the second motor area 135) are arranged side by side on the left and right, the housing 1 is provided with a second coolant injection port 17 to communicate with the second motor chamber 132 (or the second motor area 135), and inject a second coolant (such as lubricating liquid or low-temperature refrigerant) into the second motor chamber 132 to cool the second motor 32, and the lubricating oil in the second motor chamber 132 (or the second motor area 135) is atomized and discharged through the exhaust passage 15 along with the working fluid to reduce the accumulation of lubricating oil in the second motor chamber 132 (or the second motor area 135).

[0075] like Figures 1 to 4 As shown, the capacity adjustment mechanism 4 includes a first sliding valve 41 and a second sliding valve 42. The first sliding valve 41 is movably set corresponding to the first contact line L1, thereby controlling the suction pressure, exhaust pressure and exhaust time of the first compression chamber 12. The second sliding valve 42 is movably set corresponding to the second contact line L2, thereby controlling the suction pressure, exhaust pressure and exhaust time of the second compression chamber 14.

[0076] like Figures 1 to 3 As shown, the pressure sensing group 5 includes at least one intermediate pressure sensor 51, an intake pressure sensor 52 and an exhaust pressure sensor 53. The intermediate pressure sensor 51 is accommodated in the motor room 13 to obtain a current medium pressure, which is the internal fluid pressure of the motor room 13. The intake pressure sensor 52 is accommodated in the intake passage 11 to obtain an intake pressure, which is the internal fluid pressure of the intake passage 11. The exhaust pressure sensor 53 is accommodated in the exhaust passage 15 to obtain an exhaust pressure, which is the internal fluid pressure of the exhaust passage 15.

[0077] The detailed description is as follows: Figure 1 to Figure 2 As shown, the first and second embodiments of the two-stage refrigerant compressor 10 of the present invention are shown, wherein the motor chamber 13 includes a first motor chamber 131 connected to the first compression chamber 12, a second motor chamber 132 connected to the second compression chamber 14, and a connecting channel 133 whose two ends are only connected to the first motor chamber 131 and the second motor chamber 132 respectively, the first motor 22 is accommodated in the first motor chamber 131, the second motor 32 is accommodated in the second motor chamber 132, and the intermediate pressure sensor 51 is accommodated in at least one of the first motor chamber 131, the second motor chamber 132 and the connecting channel 33.

[0078] In addition, if Figure 1 to Figure 2As shown, in the first embodiment of the two-stage refrigerant compressor 10 of the present invention, the fluid inside the shell 1 passes through the motor chamber 13 in sequence through the first motor chamber 131, the connecting passage 133 and the second motor chamber 132.

[0079] Among them, Figure 1 As shown, the connecting passage 133 is a vertical passage connected between the first motor chamber 131 and the upper and lower sides of the second motor chamber 132 at both ends, that is, one end of the connecting passage 133 is connected to the second motor chamber 132 in a vertical or oblique manner (in Figure 1 After the fluid is discharged from the connecting channel 133, the fluid flows vertically to the second motor 32. The first motor chamber 131 and the second motor chamber 132 can be arranged in parallel up and down or in parallel left and right, which is not limited to this embodiment.

[0080] Or, if Figure 2 As shown, the connecting channel 133 is a curved pipe channel with both ends connected to the first motor chamber 131 and one side of the second motor chamber 132, that is, one end of the connecting channel 133 is connected to the second motor chamber 132 in an oblique or parallel manner (in Figure 2 After the fluid is discharged from the connecting channel 133, the fluid flows to the second motor 32 in an oblique or parallel manner. The first motor chamber 131 and the second motor chamber 132 can be arranged in parallel up and down or in parallel left and right, which is not limited to this embodiment.

[0081] In addition, the connecting channel 133 may also be a U-shaped channel with both ends connected to the first motor chamber 131 and one side of the second motor chamber 132, that is, one end of the connecting channel 133 is connected to the second motor chamber 132 in parallel (in a manner similar to the embodiment of FIG. Figure 1 to Figure 2 After the fluid is discharged from the connecting channel 133, it flows toward the second motor 32 in a parallel manner to reduce the vibration caused by the fluid to the running second motor 32 and the second screw 31.

[0082] Furthermore, if Figure 3 As shown, it is a third embodiment of the two-stage refrigerant compressor 10 of the present invention, wherein half of the motor chamber 13 is formed with a first motor area 134 connected to the first compression chamber 12 and the other half is formed with a second motor area 135 connected to the second compression chamber 14, the first motor 22 is accommodated in the first motor area 134, the second motor 32 is accommodated in the second motor area 135, and the intermediate pressure sensor 51 is accommodated in one of the first motor area 134 and the second motor area 135.

[0083] Again, if Figure 3As shown, in the third embodiment of the two-stage refrigerant compressor 10 of the present invention, the fluid inside the housing 1 passes through the motor chamber 13 in a manner of sequentially passing through the first motor area 134 and the second motor area 135. The first motor area 134 and the second motor area 135 can be arranged in parallel up and down or in parallel left and right, which is not limited to this embodiment.

[0084] In addition, a processor (not shown) is connected to the first motor 22, the second motor 32, the first slide valve 41, the second slide valve 42, the intermediate pressure sensor 51, the intake pressure sensor 52 and the exhaust pressure sensor 53. The processor is used to receive data on the current intermediate pressure, intake pressure and exhaust pressure, control the rotation speed of the first motor 22 and the second motor 32, and control the position of the first slide valve 41 and the second slide valve 42.

[0085] As further described below, the processor may include a central processing unit (CPU), a microprocessor (MPU) or a digital signal processor (DSP) installed on the housing 1, a remote computer (not shown), a server (not shown), the first motor 22 or the second motor 32, and an actuator connected to and driving the first sliding valve 41 and the second sliding valve 42 to move.

[0086] like Figure 5 As shown, it is a flow chart of the steps of the first embodiment of the operating method of the two-stage refrigerant compressor 10 of the present invention; Figure 6 , Figure 7 FIG. 2 is a flow chart of the first and second embodiments of the operation method of the two-stage refrigerant compressor 10 of the present invention.

[0087] The detailed description is as follows: First, Figure 5 Step a and Figures 1 to 4 , Figure 6 to Figure 7 As shown, a two-stage refrigerant compressor 10 as described above is provided, wherein the first motor 22 drives a first screw 21 thereof to rotate at a variable frequency, and the second motor 32 drives a second screw 31 thereof to rotate at a variable frequency.

[0088] Second, if Figure 5 Step b and Figures 1 to 4 , Figure 6 to Figure 7 As shown, a current temperature T1 is obtained and a preset temperature T2 is set, and the controller adjusts or maintains the rotation speed of the first motor 22 according to the value of the current temperature T1 minus the preset temperature T2.

[0089] The current temperature T1 is the indoor temperature (eg, room, freezer) where the two-stage refrigerant compressor 10 is located, and the preset temperature T2 is the desired indoor temperature (eg, room, freezer) set by the user.

[0090] In addition, if Figure 6In the first embodiment of the operating method shown, when the two-stage refrigerant compressor 10 performs refrigeration operation, if the value of the current temperature T1 minus the preset temperature T2 is equal to a first error value C1, the controller maintains the speed of the first motor 22; if the value of the current temperature T1 minus the preset temperature T2 is greater than the first error value C1, the controller increases the speed of the first motor 22; if the value of the current temperature T1 minus the preset temperature T2 is less than the first error value C1, the controller reduces the speed of the first motor 22.

[0091] Furthermore, if Figure 7 In the second embodiment of the operating method shown, when the two-stage refrigerant compressor 10 performs heating operation, the value of the current temperature T1 minus the preset temperature T2 is equal to a first error value C1, then the controller maintains the speed of the first motor 22, that is, maintains the speed of the first screw 21; the value of the current temperature T1 minus the preset temperature T2 is less than the first error value C1, then the controller increases the speed of the first motor 22, that is, increases the speed of the first screw 21; the value of the current temperature T1 minus the preset temperature T2 is greater than the first error value C1, then the controller reduces the speed of the first motor 22, that is, reduces the speed of the first screw 21.

[0092] An example is given below. When the two-stage refrigerant compressor 10 performs cooling operation, the current temperature T1 inside the freezer is measured to be 30°C. The user needs to set the preset temperature T2 inside the freezer to -20°C. The first error value C1 is ±1. When the current temperature T1 is higher than 21°C, the speed of the first screw 21 is increased. When the current temperature T1 is lower than 19°C, the speed of the first screw 21 is reduced. When the current temperature T1 is between 21 and 19°C, the current speed of the first screw 21 is maintained. On the contrary, when the two-stage refrigerant compressor 10 performs heating operation, the current temperature T1 inside the room is measured to be 20°C. The user needs to set the preset temperature T2 inside the room to be 30°C. The first error value C1 is ±1. When the current temperature T1 is higher than 31°C, the speed of the first screw 21 is reduced. When the current temperature T1 is lower than 29°C, the speed of the first screw 21 is increased. When the current temperature T1 is between 31 and 29°C, the current speed of the first screw 21 is maintained. In actual operation, the range of the first error value C1 is determined according to different setting conditions.

[0093] Third, if Figure 5 Step c and Figures 1 to 4 , Figure 6 to Figure 7 As shown, a set medium pressure P2 is calculated, and the controller adjusts or maintains the speed of the second motor 32 according to the value of the current medium pressure P1 minus the set medium pressure P2.

[0094] Further explanation is as follows: when the current value of the medium pressure P1 minus the set medium pressure P2 is equal to a second error value C2, the controller maintains the speed of the second motor 32, that is, maintains the speed of the second screw 31; when the current value of the medium pressure P1 minus the set medium pressure P2 is greater than the second error value C2, the controller increases the speed of the second motor 32, that is, increases the speed of the second screw 31; when the current value of the medium pressure P1 minus the set medium pressure P2 is less than the second error value C2, the controller reduces the speed of the second motor 32, that is, reduces the speed of the second screw 31.

[0095] The set medium pressure P2 is calculated by the following formula: Wherein, P2 is the set medium pressure, Psuc is the suction pressure, Pdis is the exhaust pressure, k1 is the first empirical coefficient, k2 is the second empirical coefficient, k3 is the third empirical coefficient, k4 is the fourth empirical coefficient, and k5 is the fifth empirical coefficient, which are empirical coefficients obtained by measurement or simulation.

[0096] In one example, measurements are performed in advance in a laboratory or on a production line to obtain a reference medium pressure, a reference suction pressure, and a reference exhaust pressure and input them into a coefficient calculation unit. The coefficient calculation unit is a calculation unit that can input the reference medium pressure, the reference suction pressure, and the reference exhaust pressure, calculate and output a first empirical coefficient, a second empirical coefficient, a third empirical coefficient, a fourth empirical coefficient, and a fifth empirical coefficient.

[0097] In addition, the measurement location is not limited to a laboratory or a production line. It can be an online system. When the actual fluid machinery is operating, the reference medium pressure, reference suction pressure, and reference exhaust pressure are measured from the fluid machinery and input into a coefficient calculation unit to calculate and output the first empirical coefficient, the second empirical coefficient, the third empirical coefficient, the fourth empirical coefficient, and the fifth empirical coefficient.

[0098] Alternatively, the reference intermediate pressure, reference suction pressure, and reference exhaust pressure are not limited to being obtained through measurement. They can be a simulation result. Computer-aided engineering (CAE) software is used to simulate the operating conditions of the fluid machinery, and the simulated reference intermediate pressure, reference suction pressure, and reference exhaust pressure are obtained and input into a coefficient calculation unit to calculate and output the first empirical coefficient, the second empirical coefficient, the third empirical coefficient, the fourth empirical coefficient, and the fifth empirical coefficient.

[0099] An example is as follows: subtract the measured current medium pressure P1 from the set medium pressure P2 calculated by the above formula. For example, the set medium pressure P2 is calculated to be 8kg / cm 2 G, the second error value C2 is ±0.2, when the current medium pressure P1 is measured to be 8.2kg / cm 2 When the medium pressure P1 is 7.8 kg / cm2, the speed of the second screw 31 will be increased. 2When the current medium pressure P1 is between 8.2 and 7.8 kg / cm 2 G, the rotation speed of the second screw 31 is maintained. In actual operation, the range of the second error value C2 is determined according to different setting conditions.

[0100] Fourth, if Figure 5 Step d and Figures 1 to 4 , Figure 6 to Figure 7 As shown, a low-pressure specific volume V1 of the first compression chamber 12, a medium-pressure specific volume V2 of the motor chamber 13, and a high-pressure specific volume V3 of the second compression chamber 14 are calculated, and the controller adjusts or maintains the position of the first slide valve 41 according to the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2, and the controller adjusts or maintains the position of the second slide valve 42 according to the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3.

[0101] Among them, the specific volume (specific volume, v) can be calculated based on the pressure, temperature and curve fitting (Curve Fitting) of the compressor. The low-pressure specific volume V1 is calculated from the pressure and temperature of the first compression chamber 12, the medium-pressure specific volume V2 is calculated from the pressure and temperature of the motor chamber 13, and the high-pressure specific volume V3 is calculated from the pressure and temperature of the second compression chamber 14. The optimal position of the slider can be calculated by selecting the relationship between the volume ratio of the compressor and the slider position according to the type of refrigerant.

[0102] Further explanation is as follows: if the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2 is equal to a third error value C3, the controller maintains the position of the first slide valve 41; if the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2 is greater than or less than (not equal to) the third error value C3, the controller adjusts the position of the first slide valve 41 by selecting the optimal position of the slider calculated by the relationship between the volume ratio of the compressor and the slider position according to the type of refrigerant; if the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3 is equal to a fourth error value C4, the controller maintains the position of the second slide valve 42; if the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3 is greater than or less than (not equal to) the fourth error value C4, the controller adjusts the position of the second slide valve 42 by selecting the optimal position of the slider calculated by the relationship between the volume ratio of the compressor and the slider position according to the type of refrigerant.

[0103] An example is given as follows. When the third error value C3 is set to 3, when the currently calculated value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2 is equal to 3 (equal to the third error value C3), the controller maintains the position of the first slide valve 41 unchanged; and when the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2 is equal to 5 (greater than the third error value C3), the controller controls the first slide valve 41 to move toward the suction end 211 of the first screw 21 to reduce the low-pressure specific volume V1 value; and when the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2 is equal to 1.5 (less than the third error value C3), the controller controls the first slide valve 41 to move toward the discharge end 212 of the first screw 21 (moving away from the suction end 211 of the first screw 21) to increase the low-pressure specific volume V1 value.

[0104] In addition, for example, when the fourth error value C4 is set to 3, the currently calculated value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3 is equal to 3 (equal to the fourth error value C4), and the controller maintains the position of the second slide valve 42; when the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3 is equal to 5 (greater than the fourth error value C4), the controller controls the second slide valve 42 to move away from the exhaust passage 15 (toward the second motor chamber 132) to reduce the medium-pressure specific volume V2 value; when the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3 is equal to 1.5 (less than the fourth error value C4), the controller controls the second slide valve 42 to move toward the exhaust passage 15 to increase the medium-pressure specific volume V2 value.

[0105] like Figure 8 As shown, it is a flow chart of the steps of the second embodiment of the operating method of the two-stage refrigerant compressor 10 of the present invention; Fig. 9 , Fig.10 FIG. 2 is a flow chart of the third and fourth embodiments of the operation method of the two-stage refrigerant compressor 10 of the present invention.

[0106] The detailed description is as follows: First, Figure 8 Step e and Figures 1 to 4 , Figures 9 and 10 As shown, a two-stage refrigerant compressor 10 as described above is provided, wherein the first motor 22 drives a first screw 21 thereof to rotate at a fixed frequency, and the second motor 32 drives a second screw 31 thereof to rotate at a variable frequency.

[0107] Second, if Figure 8 Step f and Figures 1 to 4 , Figures 9 and 10 As shown, a current temperature T1 is obtained and a preset temperature T2 is set, and the controller adjusts or maintains the position of the first slide valve 41 according to the value of the current temperature T1 minus the preset temperature T2.

[0108] The current temperature T1 is the indoor temperature (eg, room, freezer) where the two-stage refrigerant compressor 10 is located, and the preset temperature T2 is the desired indoor temperature (eg, room, freezer) set by the user.

[0109] In addition, if Fig. 9 In the third embodiment of the operating method shown, when the two-stage refrigerant compressor 10 performs refrigeration operation, the value of the current temperature T1 minus the preset temperature T2 is equal to the first error value C1, then the controller maintains the position of the first slide valve 41; the value of the current temperature T1 minus the preset temperature T2 is greater than the first error value C1, then the controller controls the first slide valve 41 to perform a loading action, and the loading action is that the first slide valve 41 moves toward the suction end 211 of the first screw 21; the value of the current temperature T1 minus the preset temperature T2 is less than the first error value C1, then the controller controls the first slide valve 41 to perform a unloading action, and the unloading action is that the first slide valve 41 moves toward the discharge end 212 of the first screw 21.

[0110] Furthermore, if Fig.10 In the fourth embodiment of the operating method shown, when the two-stage refrigerant compressor 10 performs heating operation, the value of the current temperature T1 minus the preset temperature T2 is equal to the first error value C1, then the controller maintains the position of the first slide valve 41; the value of the current temperature T1 minus the preset temperature T2 is less than the first error value C1, then the controller controls the first slide valve 41 to perform a loading action, and the loading action is that the first slide valve 41 moves toward the suction end 211 of the first screw 21; the value of the current temperature T1 minus the preset temperature T2 is greater than the first error value C1, then the controller controls the first slide valve 41 to perform a unloading action, and the unloading action is that the first slide valve 41 moves toward the discharge end 212 of the first screw 21.

[0111] An example is given below. When the two-stage refrigerant compressor 10 is in refrigeration operation, the current temperature T1 inside the freezer is measured to be 30°C. The user needs to set the preset temperature T2 inside the freezer to 20°C. The first error value C1 is ±1. When the current temperature T1 is higher than 21°C, the controller controls the first slide valve 41 to perform a loading action. The loading action is that the first slide valve 41 moves toward the suction end 211 of the first screw 21. When the current temperature T1 is lower than 19°C, the controller controls the first slide valve 41 to perform a load release action. The load release action is that the first slide valve 41 moves toward the discharge end 212 of the first screw 21. When the current temperature T1 is between 21 and 19°C, it will be maintained. The controller maintains the position of the first slide valve 41. In actual operation, the range of the first error value C1 will be determined according to different set working conditions.

[0112] On the contrary, when the two-stage refrigerant compressor 10 is in heating operation, the current temperature T1 inside the room is measured to be 20°C, and the user needs to set the preset temperature T2 inside the room to be 30°C, and the first error value C1 is ±1. When the current temperature T1 is higher than 31°C, the controller controls the first slide valve 41 to perform a load-releasing action, and the load-releasing action is that the first slide valve 41 moves toward the discharge end 212 of the first screw 21; when the current temperature T1 is lower than 29°C, the controller controls the first slide valve 41 to perform a loading action, and the loading action is that the first slide valve 41 moves toward the suction end 211 of the first screw 21; when the current temperature T1 is between 31 and 29°C, the controller maintains the position of the first slide valve 41. In actual operation, the range of the first error value C1 will be determined according to different set working conditions.

[0113] Third, if Figure 8 Steps g and Figures 1 to 4 , Figures 9 and 10 As shown, a set medium pressure P2 is calculated, and the controller adjusts or maintains the speed of the second motor 32 according to the value of the current medium pressure P1 minus the set medium pressure P2.

[0114] Further explanation is as follows: if the value of the current medium pressure P1 minus the set medium pressure P2 is equal to the second error value C2, the controller maintains the speed of the second motor 32, that is, maintains the speed of the second screw 31; if the value of the current medium pressure P1 minus the set medium pressure P2 is greater than the second error value C2, the controller increases the speed of the second motor 32, that is, increases the speed of the second screw 31; if the value of the current medium pressure P1 minus the set medium pressure P2 is less than the second error value C2, the controller reduces the speed of the second motor 32, that is, reduces the speed of the second screw 31. Here, the example of step c of the first and second embodiments is given, and it is not repeated here.

[0115] In addition, the set medium pressure P2 is calculated by the following formula: Wherein, P2 is the set medium pressure, Psuc is the suction pressure, Pd is the exhaust pressure, k1 is the first empirical coefficient, k2 is the second empirical coefficient, k3 is the third empirical coefficient, k4 is the fourth empirical coefficient, and k5 is the fifth empirical coefficient, as described above.

[0116] Fourth, if Figure 8 Steps h and Figures 1 to 4 , Figures 9 and 10 As shown, the low-pressure specific volume V1 of the first compression chamber 12, the medium-pressure specific volume V2 of the motor chamber 13 and the high-pressure specific volume V3 of the second compression chamber 14 are calculated, and the controller adjusts or maintains the position of the first slide valve 41 according to the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2, and the controller adjusts or maintains the position of the second slide valve 42 according to the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3.

[0117] Among them, the specific volume (specific volume, v) can be calculated based on the pressure, temperature and curve fitting (Curve Fitting) of the compressor. The low-pressure specific volume V1 is calculated from the pressure and temperature of the first compression chamber 12, the medium-pressure specific volume V2 is calculated from the pressure and temperature of the motor chamber 13, and the high-pressure specific volume V3 is calculated from the pressure and temperature of the second compression chamber 14. The optimal position of the slider can be calculated by selecting the relationship between the volume ratio of the compressor and the slider position according to the type of refrigerant.

[0118] Further explanation is as follows: if the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2 is equal to the third error value C3, the controller maintains the position of the first slide valve 41; if the value of the low-pressure specific volume V1 divided by the medium-pressure specific volume V2 is greater than or less than (not equal to) the third error value C3, the controller selects the optimal position of the slider calculated by the relationship between the volume ratio of the compressor and the position of the slider according to the type of refrigerant to adjust the position of the first slide valve 41; if the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3 is equal to the fourth error value C4, the controller maintains the position of the second slide valve 42; if the value of the medium-pressure specific volume V2 divided by the high-pressure specific volume V3 is greater than or less than (not equal to) the fourth error value C4, the controller selects the optimal position of the slider calculated by the relationship between the volume ratio of the compressor and the position of the slider according to the type of refrigerant to adjust the position of the second slide valve 42. Among them, the example of step d of the first and second embodiments is given, which is not repeated here.

[0119] Therefore, the present invention achieves an adjustable compression ratio by controlling the rotation speed of the first screw 21 and the rotation speed of the second screw 31, and achieves an adjustable volume ratio by controlling the position of the first slide valve 41 and the position of the second slide valve 42, so that all factors affecting the energy efficiency of the two-stage refrigerant compressor 10 are included in the controllable category, allowing the two-stage spiral compressor 10 to operate in an optimal efficiency mode under variable working conditions.

[0120] In summary, the two-stage refrigerant compressor and its operating method of the present invention are not seen in similar products and are not publicly used. They are industrially applicable, novel and progressive, and fully meet the requirements for patent applications. An application is filed in accordance with the Patent Law to protect the rights of the inventor.

Claims

1. A two-stage refrigerant compressor, characterized in that: include: A shell, wherein an air intake passage, a first compression chamber, a motor chamber, a second compression chamber and an air discharge passage are sequentially connected to each other; a first compressor module, comprising a pair of first screws accommodated in the first compression chamber and meshing with each other, and a first motor accommodated in the motor chamber and driving one of the first screws to rotate, wherein the pair of first screws define a first contact line; a second compressor module, comprising a pair of second screws accommodated in the second compression chamber and meshing with each other, and a second motor accommodated in the motor chamber and driving one of the second screws to rotate, wherein the pair of second screws define a second contact line; a capacity adjustment mechanism, comprising a first slide valve movably arranged corresponding to the first contact line and a second slide valve movably arranged corresponding to the second contact line; a pressure sensing group, comprising at least one intermediate pressure sensor, wherein the at least one intermediate pressure sensor is accommodated in the motor chamber to obtain a current intermediate pressure; and A processor is connected to the first motor, the second motor, the first slide valve, the second slide valve and the at least one intermediate pressure sensor, and the processor is used to receive the current intermediate pressure data, control the rotation speed of the first motor and the second motor, and control the position of the first slide valve and the second slide valve.

2. The two-stage refrigerant compressor according to claim 1, characterized in that: The pressure sensing group further includes an intake pressure sensor and an exhaust pressure sensor. The intake pressure sensor is accommodated in the intake passage to obtain an intake pressure. The exhaust pressure sensor is accommodated in the exhaust passage to obtain an exhaust pressure. The processor is further connected to the intake pressure sensor and the exhaust pressure sensor. The processor is used to receive data of the intake pressure and the exhaust pressure.

3. The two-stage refrigerant compressor according to claim 1, characterized in that: The motor chamber includes a first motor chamber connected to the first compression chamber, a second motor chamber connected to the second compression chamber, and a connecting passage with two ends respectively connected to the first motor chamber and the second motor chamber, the first motor is accommodated in the first motor chamber, the second motor is accommodated in the second motor chamber, and the at least one intermediate pressure sensor is accommodated in at least one of the first motor chamber, the second motor chamber and the connecting passage.

4. The two-stage refrigerant compressor according to claim 3, characterized in that: The first motor chamber and the second motor chamber are arranged side by side up and down or left and right.

5. The two-stage refrigerant compressor according to claim 3, characterized in that: The shell is provided with a first coolant spray inlet and / or a second coolant spray inlet, wherein the first coolant spray inlet is arranged and connected between the first compression chamber and the first motor chamber, and the second coolant spray inlet is connected to the second motor chamber and corresponds to the second motor arrangement.

6. The two-stage refrigerant compressor according to claim 1, characterized in that: One half of the motor chamber forms a first motor area connected to the first compression chamber, and the other half forms a second motor area connected to the second compression chamber, the first motor is accommodated in the first motor area, the second motor is accommodated in the second motor area, and the at least one intermediate pressure sensor is accommodated in at least one of the first motor area and the second motor area.

7. The two-stage refrigerant compressor according to claim 6, characterized in that: The first motor area and the second motor area are arranged side by side up and down or left and right.

8. The two-stage refrigerant compressor according to claim 6, characterized in that: The shell is provided with a first coolant spray inlet and / or a second coolant spray inlet, wherein the first coolant spray inlet is arranged and connected between the first compression chamber and the first motor area, and the second coolant spray inlet is connected to the second motor area and corresponds to the second motor arrangement.

9. A method for operating a two-stage refrigerant compressor, characterized in that: The steps include: a) providing a two-stage refrigerant compressor as claimed in claim 2, wherein the first motor drives one of the first screws to rotate at a variable frequency, and the second motor drives one of the second screws to rotate at a variable frequency; b) obtaining a current temperature and setting a preset temperature, wherein the controller adjusts or maintains the first motor speed according to a value obtained by subtracting the preset temperature from the current temperature; c) calculating a set medium pressure, the controller adjusting or maintaining the second motor speed according to the value of the current medium pressure minus the set medium pressure; and d) calculating a low-pressure specific volume of the first compression chamber, a medium-pressure specific volume of the motor chamber, and a high-pressure specific volume of the second compression chamber, the controller adjusting or maintaining the position of the first slide valve according to the value of the low-pressure specific volume divided by the medium-pressure specific volume, and the controller adjusting or maintaining the position of the second slide valve according to the value of the medium-pressure specific volume divided by the high-pressure specific volume.

10. The operating method of the two-stage refrigerant compressor according to claim 9, characterized in that: The current temperature is the room temperature where the two-stage refrigerant compressor is located. The preset temperature is set by the user. The set medium pressure is calculated by the following formula: P2 = Wherein, P2 is the set medium pressure, Psuc is the suction pressure, Pdis is the exhaust pressure, k1 is the first empirical coefficient, k2 is the second empirical coefficient, k3 is the third empirical coefficient, k4 is the fourth empirical coefficient, and k5 is the fifth empirical coefficient.

11. The operating method of the two-stage refrigerant compressor according to claim 9, characterized in that: In step b), when the two-stage refrigerant compressor performs cooling operation, if the value of the current temperature minus the preset temperature is equal to a first error value, the controller maintains the first motor speed; if the value of the current temperature minus the preset temperature is greater than the first error value, the controller increases the first motor speed; if the value of the current temperature minus the preset temperature is less than the first error value, the controller reduces the first motor speed.

12. The operating method of the two-stage refrigerant compressor according to claim 9, characterized in that: In step b), when the two-stage refrigerant compressor performs heating operation, if the value of the current temperature minus the preset temperature is equal to a first error value, the controller maintains the first motor speed; if the value of the current temperature minus the preset temperature is less than the first error value, the controller increases the first motor speed; if the value of the current temperature minus the preset temperature is greater than the first error value, the controller reduces the first motor speed.

13. The operating method of the two-stage refrigerant compressor according to claim 9, characterized in that: In step c), if the value of the current medium pressure minus the set medium pressure is equal to a second error value, the controller maintains the second motor speed; if the value of the current medium pressure minus the set medium pressure is greater than the second error value, the controller increases the second motor speed; if the value of the current medium pressure minus the set medium pressure is less than the second error value, the controller reduces the second motor speed.

14. The operating method of the two-stage refrigerant compressor according to claim 9, characterized in that: In step d), if the value of the low-pressure specific volume divided by the medium-pressure specific volume is equal to a third error value, the controller maintains the position of the first slide valve; if the value of the low-pressure specific volume divided by the medium-pressure specific volume is greater than or less than the third error value, the controller adjusts the position of the first slide valve; if the value of the medium-pressure specific volume divided by the high-pressure specific volume is equal to a fourth error value, the controller maintains the position of the second slide valve; if the value of the medium-pressure specific volume divided by the high-pressure specific volume is greater than or less than the fourth error value, the controller adjusts the position of the second slide valve.

15. A method for operating a two-stage refrigerant compressor, characterized in that: The steps include: e) providing a two-stage refrigerant compressor as claimed in claim 2, wherein the first motor drives one of the first screws to rotate at a fixed frequency, and the second motor drives one of the second screws to rotate at a variable frequency; f) obtaining a current temperature and setting a preset temperature, wherein the controller adjusts or maintains the position of the first slide valve according to a value obtained by subtracting the preset temperature from the current temperature; g) calculating a set medium pressure, the controller adjusting or maintaining the second motor speed according to the value of the current medium pressure minus the set medium pressure; and h) calculating a low-pressure specific volume of the first compression chamber, a medium-pressure specific volume of the motor chamber, and a high-pressure specific volume of the second compression chamber, the controller adjusting or maintaining the position of the first slide valve according to the value of the low-pressure specific volume divided by the medium-pressure specific volume, and the controller adjusting or maintaining the position of the second slide valve according to the value of the medium-pressure specific volume divided by the high-pressure specific volume.

16. The operating method of the two-stage refrigerant compressor according to claim 15, characterized in that: The current temperature is the indoor temperature of the two-stage refrigerant compressor, the preset temperature is set by the user, and the set medium pressure is calculated by the following formula: Wherein, P2 is the set medium pressure, Psuc is the suction pressure, Pdis is the exhaust pressure, k1 is the first empirical coefficient, k2 is the second empirical coefficient, k3 is the third empirical coefficient, k4 is the fourth empirical coefficient, and k5 is the fifth empirical coefficient.

17. The operating method of the two-stage refrigerant compressor according to claim 15, characterized in that: In step f), the first screw has a suction end and a discharge end. When the two-stage refrigerant compressor performs refrigeration operation, the value of the current temperature minus the preset temperature is equal to a first error value, then the controller maintains the position of the first slide valve. When the value of the current temperature minus the preset temperature is greater than the first error value, then the controller controls the first slide valve to perform a loading action, and the loading action is that the first slide valve moves toward the suction end. When the value of the current temperature minus the preset temperature is less than the first error value, then the controller controls the first slide valve to perform a unloading action, and the unloading action is that the first slide valve moves toward the discharge end.

18. The operating method of the two-stage refrigerant compressor according to claim 15, characterized in that: In step f), the first screw has a suction end and a discharge end. When the two-stage refrigerant compressor performs heating operation, the value of the current temperature minus the preset temperature is equal to a first error value, then the controller maintains the position of the first slide valve. If the value of the current temperature minus the preset temperature is less than the first error value, then the controller controls the first slide valve to perform a loading action, and the loading action is that the first slide valve moves toward the suction end. If the value of the current temperature minus the preset temperature is greater than the first error value, then the controller controls the first slide valve to perform a unloading action, and the unloading action is that the first slide valve moves toward the discharge end.

19. The operating method of the two-stage refrigerant compressor according to claim 15, characterized in that: In step g), if the value of the current medium pressure minus the set medium pressure is equal to a second error value, the controller maintains the second motor speed; if the value of the current medium pressure minus the set medium pressure is greater than the second error value, the controller increases the second motor speed; if the value of the current medium pressure minus the set medium pressure is less than the second error value, the controller reduces the second motor speed.

20. The operating method of the two-stage refrigerant compressor according to claim 15, characterized in that: In step h), if the value of the low-pressure specific volume divided by the medium-pressure specific volume is equal to a third error value, the controller maintains the position of the first slide valve; if the value of the low-pressure specific volume divided by the medium-pressure specific volume is greater than or less than the third error value, the controller adjusts the position of the first slide valve; if the value of the medium-pressure specific volume divided by the high-pressure specific volume is equal to a fourth error value, the controller maintains the position of the second slide valve; if the value of the medium-pressure specific volume divided by the high-pressure specific volume is greater than or less than the fourth error value, the controller adjusts the position of the second slide valve.

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