JP4827859B2 - Air conditioner and operation method thereof - Google Patents

Description

  The present invention relates to an air conditioner and an operating method thereof, and more particularly to an air conditioner and a method of operating the air conditioner in which a compressor and an expander are connected coaxially and power is recovered by the expander.

Ozone depletion potential is zero, and much less carbon dioxide compared to even chlorofluorocarbon global warming potential (hereinafter, referred to CO ₂₎ is an air conditioning apparatus using a refrigerant have been focused in recent years, CO ₂ refrigerant When the critical temperature is as low as 31.06 ° C. and a temperature higher than this temperature is used, condensation of the CO ₂ refrigerant occurs on the high pressure side (compressor outlet to radiator to decompressor inlet) of the air conditioner. It becomes a non-supercritical state, and the operating efficiency (COP) of the air conditioner is reduced as compared with the conventional refrigerant. Therefore, means for improving COP is important in an air conditioner using a CO ₂ refrigerant.

  As such means, there has been proposed a refrigeration cycle in which an expander is provided instead of the decompressor, and the pressure energy at the time of expansion is recovered and used as power. Here, in an air conditioner having a configuration in which a positive displacement compressor and an expander are connected to one shaft, if the cylinder volume of the compressor is VC and the cylinder volume of the expander is VE, VC / VE (design volume ratio) A ratio of volumetric circulation flowing through each of the compressor and expander is determined. When the density of the refrigerant at the outlet of the evaporator (refrigerant flowing into the compressor) is DC and the density of the refrigerant at the outlet of the radiator (refrigerant flowing into the expander) is DE, the mass circulation amount that flows through each of the compressor and the expander Are equal, “VC × DC = VE × DE”, that is, the relationship “VC / VE = DE / DC” is established. Since VC / VE (design volume ratio) is a constant determined at the time of designing the device, the refrigeration cycle tries to balance so that DE / DC (density ratio) is always constant. (Hereinafter, this is called “constant density ratio constraint”.)

  However, since the usage conditions of the air conditioner are not necessarily constant, if the design volume ratio assumed at the time of design differs from the density ratio in the actual operation state, the best condition is due to the “constant density ratio constraint”. It becomes difficult to adjust to the high pressure side pressure.

  Therefore, a configuration and a control method have been proposed in which a bypass flow path for bypassing the expander is provided and the amount of refrigerant flowing into the expander is controlled to adjust to the best high-pressure side pressure (see, for example, Patent Document 1). .

  In addition, an internal heat exchanger that exchanges heat between the refrigerant flowing into the expander and the refrigerant flowing into the compressor and a bypass flow path thereof are provided, and the amount of refrigerant flowing into the expander is controlled by switching the presence or absence of heat exchange. A configuration for adjusting to the best high pressure side pressure has also been proposed (see, for example, Patent Document 2).

Japanese Patent No. 3708536 (pages 10 to 12, FIG. 1) Japanese Unexamined Patent Publication No. 2006-90639 (pages 18-19, FIG. 9)

  However, in the above-mentioned Patent Document 1, when the density ratio in the actual operation state is smaller than the design volume ratio, it is possible to adjust to the best high pressure side pressure by flowing the refrigerant through the bypass flow path that bypasses the expander. Although the configuration and the control method are described, since the power collected by the expander decreases when the refrigerant flows through the bypass flow path, there has been a problem that the operating efficiency (COP) of the air conditioner decreases.

  In addition, when the amount bypassing the expander is large, the expansion speed of the expander is low and the lubrication state at the sliding portion is deteriorated. When the rotation speed of the expander is extremely small, oil stays in the path of the expander and There was a problem that the reliability was lowered due to oil depletion of the oil and the start of refrigerant stagnation at the time of restart.

  Further, in Patent Document 2, it is possible to cope with a rough difference in density ratio due to a difference in operation mode such as cooling and heating by switching the presence or absence of heat exchange between the refrigerant flowing into the expander and the refrigerant flowing into the compressor. However, there is a problem that the operating efficiency (COP) of the air conditioner decreases because it cannot cope with the change in the optimum high-pressure side pressure due to changes in the outside air or room temperature in the same mode.

  The expander, compressor, and drive source are all integrated, and the drive source / expander / compressor integrated machine has a complicated mechanism and seal, and has a large number of parts, and high precision in the machining and assembly processes. In addition, there has been a design or manufacturing problem that requires complexity.

  Therefore, the object of the present invention is to achieve the best high pressure side pressure adjustment even when the density ratio in the actual operation state is smaller than the design volume ratio, and to improve the operation efficiency of the air conditioner without bypassing the expander. It is to obtain an air conditioner and an operation method thereof.

  An air conditioner according to the present invention includes a main compressor, a radiator, an expander, and an evaporator in order, and an air conditioner including an expander and a subcompressor coupled to a single shaft. In the apparatus, a compression bypass passage for bypassing from the middle of the compression process in the main compressor to after completion of the compression process, a sub-compressor provided on the compression bypass passage, and a main compressor on the compression bypass passage A compression bypass valve located between the compressor and the sub-compressor, and a control device for operating control of the operation of the compression bypass valve, the control device changing the opening of the compression bypass valve, The pressure is adjusted.

  In addition, the air conditioner according to the present invention connects a main compressor, a sub compressor, a radiator, an expander, and an evaporator in order, and connects the expander and the sub compressor to a single shaft. In the air conditioner, an internal heat exchanger that exchanges heat between the refrigerant on the main compressor inflow side and the refrigerant on the expander inflow side, and a heat exchange bypass flow path that bypasses the internal heat exchanger on the expander inflow side A heat exchange bypass valve provided on the heat exchange bypass flow path and a control device for operating control of the heat exchange bypass valve, wherein the control device changes an opening degree of the heat exchange bypass valve. Thus, the high-pressure side pressure is adjusted.

  The air conditioner according to the present invention includes a sub-compressor, a main compressor, a radiator, an expander, and an evaporator connected in order, and the expander and the sub-compressor are connected to a single shaft. In the air conditioner, the refrigerant on the inflow side of the sub compressor exchanges heat with the refrigerant on the inflow side of the expander, and a heat exchange bypass flow path that bypasses the internal heat exchanger on the inflow side of the expander A heat exchange bypass valve provided on the heat exchange bypass flow path and a control device for operating control of the heat exchange bypass valve, wherein the control device changes an opening degree of the heat exchange bypass valve. Thus, the high-pressure side pressure is adjusted.

  According to the present invention, even in an air conditioner using an expander that is difficult to adjust to the best high pressure side pressure due to a constant density ratio restriction, power recovery is always performed in a wide operating range, and efficiency is improved. An air conditioner capable of good operation and an operation method of the air conditioner are obtained.

Embodiment 1 FIG.
1 to 4 show an air conditioner of the present invention, FIG. 1 is a refrigerant circuit diagram of the air conditioner, FIG. 2 is a cross-sectional view of a main compressor 1, and FIG. 3 is a control performed by a control device. FIG. 4 is an operation diagram showing cooperative control between the compression bypass valve and the pre-expansion valve. The air conditioner of the present invention is a heat pump machine that can perform cooling and heating operations by directly exchanging heat with air. In FIG. 1, 1 is a main compressor, 2 is a compression bypass passage, 3 is a compression bypass valve, 4 is a sub compressor, 5 is a first four-way valve, 6 is an outdoor heat exchanger, 7 is a second four-way valve, 8 is a pre-expansion valve, 9 is an expander, 10 is a drive shaft, 11a and 11b are expansion valves, 12a and 12b are indoor heat exchangers. 13 is an outdoor unit. The outdoor unit 13 includes a main compressor 1, a compression bypass passage 2, a compression bypass valve 3, a sub compressor 4, a first four-way valve 5, an outdoor heat exchanger 6, a second four-way valve 7, It comprises a pre-expansion valve 8, an expander 9, and a drive shaft 10. Reference numerals 14a and 14b denote indoor units, and the indoor units 14a and 14b include indoor expansion valves 11a and 11b and indoor heat exchangers 12a and 12b. The outdoor unit 13 and the indoor units 14a and 14b are connected by a refrigerant pipe branched in the middle. In the present embodiment, the case where two indoor units are connected is described, but one or three or more indoor units may be used. Further, the indoor expansion valves 11a and 11b may be in the outdoor unit 12 as long as they are between the expander 9 and the indoor heat exchangers 12a and 12b, or only one refrigerant pipe before branching may be provided. good.

  The sub-compressor 4 and the expander 9 are positive displacement types, and take, for example, a scroll type. The main compressor 1 is driven by a drive source such as a motor. The sub compressor 4 and the expander 9 are connected by a drive shaft 10, and the driving power obtained by expanding the refrigerant by the expander 9 compresses the refrigerant by the sub compressor 4 via the drive shaft 10. The input of the air conditioner can be reduced.

  In addition, the second four-way valve 7 is used as a flow path switching device for making the refrigerant flow direction and the rotation direction of the expander 9 the same regardless of the operating state, and the flow path is synchronized with the first four-way valve 5. Switches. Carbon dioxide is used as the refrigerant. Reference numeral 15 denotes a control device. 16 is a temperature sensor for detecting the temperature of the refrigerant gas joined by the main compressor 1 and the sub compressor 4, 17a and 17b are temperature sensors for detecting the intermediate refrigerant temperature of the indoor heat exchangers 12a and 12b, and 18a and 18b are indoors. The temperature sensors 19a and 19b detect the cooling outlet refrigerant temperature of the heat exchangers 12a and 12b, and the temperature sensors 19a and 19b detect the heating outlet refrigerant temperature of the indoor heat exchangers 12a and 12b. Based on the information obtained by the temperature sensors 16, 17 a, 17 b, 18 a, 18 b, 19 a, 19 b, the operation control of the air conditioner is performed by the control device 15, and the operation of the main compressor 1, the rotational speed, The air flow rate of each heat exchanger, switching between the first four-way valve 5 and the second four-way valve 7, the opening degree of the compression bypass valve 3, the pre-expansion valve 8, and the indoor expansion valves 11a and 11b are controlled.

FIG. 2 is a cross-sectional view of the main compressor 1. Reference numeral 101 denotes a shell, 102 denotes a motor as a drive source, 103 denotes a shaft, 104 denotes a peristaltic scroll, 105 denotes a fixed scroll, 106 denotes an inflow pipe, 112 denotes an outflow pipe, and 114 denotes a bypass pipe. Reference numeral 108 denotes a low pressure space, which is electrically connected to the inflow pipe 106. Reference numeral 111 denotes a high-pressure space that is electrically connected to the outflow pipe 112. Reference numerals 108 and 109 denote compression chambers, which are formed by combining a scroll scroll 104 having a scroll shape and a fixed scroll 105 with each other. The compression chamber 109 is in the center of the scroll shape, and the compression chamber 108 is located outside the compression chamber 109 and is located in the middle of the compression process. Reference numeral 110 denotes an outflow port, which is provided in the fixed scroll 105 and conducts the compression chamber 109 and the high-pressure space 111. Reference numeral 113 denotes a compression bypass pipe, which is provided in the fixed scroll 105 and conducts the compression chamber 108 and the bypass pipe 114 fixed to the fixed scroll 105. The position of the outflow port is a position that satisfies the following equation (1).

(Compression chamber volume immediately after the outlet port of the main compressor 1 is connected) / (stroke volume of the main compressor 1)
X (Built-in volume ratio of sub-compressor 4) ≒ (Built-in volume ratio of main compressor 1)

  The inflow pipe 106 is an inlet of the main compressor 1 and is connected to the first four-way valve 5. The outflow pipe 112 is an outlet of the main compressor 1 and joins with the outlet of the sub compressor 4 and is connected to the first four-way valve 5. The bypass pipe 114 is connected to the compression bypass channel 2.

  Next, regarding the operation at the time of operation of the refrigeration cycle apparatus configured as described above, the stroke volume of the sub compressor 4 is VC, the stroke volume of the expander 9 is VE, the inflow refrigerant density of the sub compressor 4 is DC, The inflow refrigerant density of the expander 9 will be described as DE.

Cooling operation with (DE / DC) ≈ (VC / VE) First, the cooling is such that the density ratio (DE / DC) in the actual operation state is substantially equal to the design volume ratio (VC / VE) assumed at the time of design. The case of driving will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 1, and the outdoor heat exchanger 6 functions as a radiator (condenser) and the indoor heat exchangers 12a and 12b function as an evaporator.

  The operation inside the main compressor 1 will be described. When power is supplied to the main compressor 1, rotational power is generated in the motor 102, which is a driving source, and is transmitted to the peristaltic scroll 104 via the shaft 103. The peristaltic scroll 104 performs peristaltic motion with respect to the fixed scroll 105 by rotational power and an Oldham ring (not shown), and the plurality of compression chambers move from the outer peripheral side of the scroll shape to the center while reducing the volume. The refrigerant flowing in from the inflow pipe 106 passes through the low-pressure space 107 and enters the outer peripheral side compression chamber, and in the compression process, the pressure rises to the compression chamber 109 and becomes high pressure. Thereafter, it passes through the outflow port 110 and the high-pressure space 111 and flows out of the compressor through the outflow pipe 112.

  A part of the refrigerant existing in the compression chamber 108 located in the middle of the compression process passes through the compression bypass port 113 and flows out of the compressor from the bypass pipe 114. The refrigerant pressure in the bypass pipe 114 is a magnitude between the refrigerant pressure in the inflow pipe 106 and the refrigerant pressure in the outflow pipe 112. When the position of the compression bypass port 113 is changed to the center side of the scroll shape, the refrigerant pressure in the compression bypass pipe 113 becomes close to the refrigerant pressure in the outflow pipe 112.

  The operation of the air conditioner will be described. A part of the low-pressure refrigerant flowing in from the inlet (inflow pipe 106) of the main compressor 1 becomes high-pressure refrigerant through the entire compression process, and flows out from the outlet (outflow pipe 112) of the main compressor 1. The remaining refrigerant flows out from the bypass pipe 114 to the compression bypass passage 2 as an intermediate-pressure refrigerant that is between the high pressure and the low pressure in the middle of the compression process. The bypassed refrigerant passes through the compression bypass valve 3, the flow rate is adjusted, and the refrigerant flows into the sub compressor 4. In the sub-compressor 4, the refrigerant is compressed from the intermediate pressure to the high pressure, merges with the refrigerant after flowing out of the main compressor 1, passes through the first four-way valve 5, and reaches the outdoor heat exchanger 6. The outdoor heat exchanger 6 exchanges heat with the outside air and is cooled to lower the temperature. Thereafter, the refrigerant passes through the second four-way valve 7 and the pre-expansion valve 8 and flows into the expander 9, and the refrigerant is depressurized from high pressure to low pressure to be in a low pressure two-phase state. Thereafter, it branches through the second four-way valve 7, passes through the expansion valves 11a and 11b, absorbs heat from the indoor air in the indoor heat exchangers 12a and 12b, performs a cooling operation, and passes through the first four-way valve 5. Into the main compressor 1.

Heating operation with (DE / DC) ≈ (VC / VE) Next, the density ratio (DE / DC) in the actual operation state is approximately equal to the design volume ratio (VC / VE) assumed at the time of design. The case of driving will be described. The first four-way valve 5 and the second four-way valve 7 are set as indicated by broken lines in FIG. 1, and the outdoor heat exchanger 6 functions as an evaporator and the indoor heat exchangers 12a and 12b function as radiators (condensers). Since the internal operation of the main compressor 1 is the same as that during the cooling operation, it will be omitted and the operation of the air conditioner will be described.

  The refrigerant that has become high-pressure refrigerant through the compression process of the main compressor 1 and the sub compressor 4 passes through the first four-way valve 5 and branches, and the indoor air is heated by the indoor heat exchangers 12a and 12b. carry out. Thereafter, the air passes through the indoor expansion valves 11a and 11b and is collected, passes through the second four-way valve 7 and the pre-expansion valve 8, flows into the expander 9, and the refrigerant is decompressed from high pressure to low pressure to be in a low pressure two-phase state. . Thereafter, it passes through the second four-way valve 7, exchanges heat with the outside air in the outdoor heat exchanger 6, passes through the first four-way valve 5, and flows into the main compressor 1.

Cooling operation with (DE / DC)> (VC / VE) Next, the density ratio (DE / DC) in the actual operation state is larger than the design volume ratio (VC / VE) assumed at the time of design. The case will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 1, and the outdoor heat exchanger 6 functions as a radiator (condenser) and the indoor heat exchangers 12a and 12b function as an evaporator. In this case, due to the restriction of a constant density ratio, the refrigeration cycle tries to balance in a state where the high-pressure pressure is reduced so that the inlet refrigerant density (DE) of the expander 9 becomes small. However, the operating efficiency is reduced when the high pressure is lower than the desired pressure.

  For this reason, if the compression bypass valve 3 is not in the fully closed state, the compression bypass valve 3 is operated in the closing direction, and the refrigerant compressed and discharged by the sub-compressor 4 is compressed and discharged by the main compressor 1. By this operation, the required compression power of the sub-compressor 4 is reduced and the rotational speed of the expander 9 is increased, so that the inlet density of the expander 9 is lowered and stabilized.

  Alternatively, if the compression bypass valve 3 is in the fully closed state, the pre-expansion valve 8 is operated in the closing direction, the refrigerant flowing into the expander 9 is expanded, and the refrigerant density is reduced.

  By these operations, the high-pressure side pressure can be increased and adjusted to a desired pressure, and since there is no refrigerant that bypasses the expander, an efficient operation can be performed. The high-pressure side pressure is arbitrary as long as it is a pressure from one of the main compressor 1 and the sub-compressor 4 to the pre-expansion valve 8.

On the contrary, in the cooling operation with (DE / DC) <(VC / VE), the density ratio (DE / DC) in the actual operation state is smaller than the design volume ratio (VC / VE) assumed at the time of design. The case will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 1, and the outdoor heat exchanger 6 functions as a radiator (condenser) and the indoor heat exchangers 12a and 12b function as an evaporator. In this case, due to the restriction of the constant density ratio, the refrigeration cycle tries to balance with the high pressure increased so that the inlet refrigerant density (DE) of the expander 9 is increased. However, the operating efficiency is reduced when the high pressure is higher than the desired pressure.

  For this reason, if the pre-expansion valve 8 is not fully opened, the pre-expansion valve 8 is operated in the opening direction so that the refrigerant flowing into the expander 9 is not expanded, and the refrigerant density is increased.

  Alternatively, if the pre-expansion valve 8 is in a fully open state, the compression bypass valve 3 is operated in the opening direction, and the refrigerant to be compressed and discharged by the main compressor 1 is compressed and discharged by the sub compressor 4. This operation increases the required compression power of the sub-compressor 4 and attempts to reduce the rotational speed of the expander 9, so that the inlet density of the expander 9 is increased and stabilized.

  By these operations, the high-pressure side pressure can be reduced and adjusted to a desired pressure, and since there is no refrigerant that bypasses the expander, efficient operation can be performed.

In addition to the heating operation when (DE / DC) ≠ (VC / VE), the density ratio (DE / DC) in the actual operation state is different from the design volume ratio (VC / VE) assumed at the time of design. In some cases, the cooling operation and the operations of the expander 9 and the sub-compressor 4 are the same and will be omitted.

  Next, as a specific operation method of the compression bypass valve 3 and the pre-expansion valve 8, the control performed by the control device 15 will be described based on the flowchart shown in FIG.

  This air conditioner control uses a correlation between the high-pressure side pressure and the discharge temperature to measure the discharge that can be measured relatively inexpensively, regardless of the high-pressure side pressure, which requires a high-cost sensor to measure. The compression bypass valve 3 and the pre-expansion valve 8 are controlled by the temperature.

  During operation of the refrigeration cycle device, the optimum high-pressure side pressure is not always constant, and is stored in advance as a table in the ROM or the like in the control device 15 based on the outside air during operation, the required load capacity, etc., and the target discharge temperature is determined. (Step 200). Next, the detected value (discharge temperature) (step 201) from the temperature sensor 16 is captured. The target discharge temperature is compared with the discharge temperature taken in step 201 (step 202).

  When the discharge temperature is lower than the target discharge temperature, the high-pressure side pressure tends to be lower than the optimum pressure, so it is first determined whether or not the compression bypass valve 3 is fully closed (step 203). When the compression bypass valve 3 is fully closed, the pre-expansion valve 8 is operated in the closing direction (step 204), the refrigerant flowing into the expander 9 is decompressed, the refrigerant density is reduced, and the high-pressure side pressure and discharge are reduced. Increase temperature. If the compression bypass valve 3 is not fully closed, the compression bypass valve 3 is operated in the closing direction (step 205), and the refrigerant compressed and discharged by the sub compressor 4 is compressed and discharged by the main compressor 1. To increase the high-pressure side pressure and the discharge temperature.

  On the other hand, when the discharge temperature is higher than the target discharge temperature, the high-pressure side pressure tends to be higher than the optimum pressure, so it is first determined whether or not the pre-expansion valve 8 is fully open (step 206). . When the pre-expansion valve 8 is fully open, the compression bypass valve 3 is operated in the opening direction (step 207), and the refrigerant compressed and discharged by the main compressor 1 is compressed and discharged by the sub compressor 4. Reduce the high pressure and discharge temperature. Further, when the pre-expansion valve 8 is not fully opened, the pre-expansion valve 8 is operated in the opening direction (step 208) so that the refrigerant flowing into the expander 9 is not decompressed so as not to reduce the refrigerant density. As a result, the high-pressure side pressure and the discharge temperature are reduced.

  After the above steps, the process returns to step 200, and thereafter repeats from step 200 to step 208, thereby performing control in which the compression bypass valve 3 and the pre-expansion valve 8 are linked as shown in FIG.

  As described above, the air conditioner (Embodiment 1) shown in FIGS. 1 to 4 uses an expander that is difficult to maintain an optimum high-pressure side pressure due to a constant density ratio restriction. In the conventional refrigeration cycle apparatus, the compression bypass valve 3 and the pre-expansion valve are used regardless of whether the density ratio (DE / DC) in the actual operation state is smaller or larger than the design volume ratio (VC / VE) assumed at the time of design. In order to adjust the pressure to the desired high pressure side by opening operation of 8 and reliably recover the power without bypassing the expander, it is possible to operate without lowering the operation efficiency and capacity. An air conditioner that can ensure the reliability of the above is provided.

  Also, there is a concern when the amount bypassing the expander is large, the expansion speed of the expander is low, the lubrication state at the sliding part deteriorates, the expansion further, the oil stays in the path of the expander, the exhaustion of the oil in the compressor, restart It is possible to reduce a decrease in reliability such as the start of stagnation of the refrigerant.

  Further, since the position of the outflow port 110 of the main compressor 1 satisfies (Equation 1), the refrigerant flowing in from the inflow pipe 106 of the main compressor 1 and completing the compression stroke and out of the outflow pipe 112, In the refrigerant that bypasses from the middle of the compression stroke of the compressor 1 and flows out from the bypass pipe 114 and flows out again through the compression stroke in the sub-compressor 4, both of the built-in volume ratios are substantially the same, and one is overcompressed, On the other hand, there is no situation such as insufficient compression, and the refrigerant can be efficiently compressed.

  The function is divided into a main compressor 1 having a drive source and a sub-compressor 4 driven by the expansion power of the expander 9. Since structural design and functional design can also be divided, there are fewer design and manufacturing issues compared to a drive source / expander / compressor integrated unit.

  Note that the determination that the compression bypass valve 3 and the pre-expansion valve 8 are fully opened or fully closed may not require the valves to be physically fully opened or fully closed. The determination may be made based on the maximum opening or the minimum opening close to the fully-opened or fully-closed predetermined in consideration.

Although the refrigerant of the air conditioner has been described as a carbon dioxide (CO _2), and other refrigerants, for example, the same effect can R410A, etc. is obtained.

Embodiment 2. FIG.
Another air conditioner of the present invention shown in FIGS. 5 to 7 has the same configuration as the air conditioner shown in FIGS. 1 to 4, and the same functional parts are denoted by the same reference numerals and description thereof is omitted. To do. FIG. 5 is a refrigerant circuit diagram of the air conditioner. FIG. 6 is a flowchart showing a control method of the air conditioner. FIG. 7 is an operation diagram of the control means of the air conditioner.

  In FIG. 5, 20 is a main compressor, which is driven by a drive source. Compared with the air conditioner shown in FIGS. 1 to 4, there is no path to bypass from the middle of the compression process to the outlet, and the internal heat exchanger 21 provided in the inlet pipe of the main compressor 1 and the expander 9 A heat exchange bypass channel 22 and a heat exchange bypass valve 23 connected to the inlet pipe are provided, and the other configurations are the same.

  Next, regarding the operation at the time of operation of the refrigeration cycle apparatus configured as described above, the stroke volume of the sub compressor 4 is VC, the stroke volume of the expander 9 is VE, the inflow refrigerant density of the sub compressor 4 is DC, The inflow refrigerant density of the expander 9 will be described as DE.

Cooling operation with (DE / DC) ≈ (VC / VE) First, the cooling is such that the density ratio (DE / DC) in the actual operation state is substantially equal to the design volume ratio (VC / VE) assumed at the time of design. The case of driving will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 5, and the outdoor heat exchanger 6 acts as a radiator (condenser) and the indoor heat exchangers 12a and 12b act as evaporators.

  The refrigerant flowing into the internal heat exchanger 21 is heated, flows into the main compressor 20, passes through a compression process, becomes an intermediate-pressure refrigerant, flows into the sub-compressor 4, and further passes through a compression process to become a high-pressure refrigerant. It passes through the first four-way valve 5 and is cooled by exchanging heat with the outside air in the outdoor heat exchanger. Next, it passes through the second four-way valve 7 and is cooled by the internal heat exchanger 21. The refrigerant that does not pass through the internal heat exchanger 21 passes through the heat exchange bypass flow path 22, is adjusted in flow rate by the heat exchange bypass valve 23, and merges with the refrigerant that has flowed out of the internal heat exchanger 21. Thereafter, it passes through the pre-expansion valve 8 and is expanded to a low pressure by the expander 9. Thereafter, the refrigerant passes through the second four-way valve 7 and the pre-expansion valve 8 and flows into the expander 9, and the refrigerant is depressurized from high pressure to low pressure to be in a low pressure two-phase state. After that, the second four-way valve 7 is branched and passes through the expansion valves 11a and 11b, and the indoor heat exchangers 12a and 12b absorb the heat from the room air to perform the cooling operation, and passes through the first four-way valve 5 and passes through the main compressor. Flows into 1.

Cooling operation with (DE / DC)> (VC / VE) Next, the density ratio (DE / DC) in the actual operation state is larger than the design volume ratio (VC / VE) assumed at the time of design. The case will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 5, and the outdoor heat exchanger 6 acts as a radiator (condenser) and the indoor heat exchangers 12a and 12b act as evaporators. In this case, due to the restriction of a constant density ratio, the refrigeration cycle tries to balance in a state where the high-pressure pressure is reduced so that the inlet refrigerant density (DE) of the expander 9 becomes small. However, the operating efficiency is reduced when the high pressure is lower than the desired pressure.

  For this reason, if the heat exchanger bypass valve 23 is not fully open, the heat exchanger bypass valve 23 is operated in the opening direction to reduce the refrigerant passing through the internal heat exchanger 21, so that the heat exchange amount is reduced and the expander The inlet density of 9 is lowered and stabilized.

  Or if the heat exchanger bypass valve 23 is a full open state, the pre-expansion valve 8 will be operated in a closing direction, the refrigerant | coolant which flows in into the expander 9 will be expanded, and a refrigerant density will be reduced.

  By these operations, the high-pressure side pressure can be increased and adjusted to a desired pressure, and since there is no refrigerant that bypasses the expander, an efficient operation can be performed.

On the contrary, in the cooling operation with (DE / DC) <(VC / VE), the density ratio (DE / DC) in the actual operation state is smaller than the design volume ratio (VC / VE) assumed at the time of design. The case will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 1, and the outdoor heat exchanger 6 functions as a radiator (condenser) and the indoor heat exchangers 12a and 12b function as an evaporator. In this case, due to the restriction of the constant density ratio, the refrigeration cycle tries to balance with the high pressure increased so that the inlet refrigerant density (DE) of the expander 9 is increased. However, the operating efficiency is reduced when the high pressure is higher than the desired pressure.

  For this reason, if the pre-expansion valve 8 is not fully opened, the pre-expansion valve 8 is operated in the opening direction so that the refrigerant flowing into the expander 9 is not expanded, and the refrigerant density is increased.

  Alternatively, if the pre-expansion valve 8 is fully open, the heat exchange bypass valve 23 is operated in the closing direction to increase the amount of refrigerant passing through the internal heat exchanger 21, so that the heat exchange amount increases and the inlet density of the expander 9 increases. The rise will rise and stabilize.

  By these operations, the high-pressure side pressure can be reduced and adjusted to a desired pressure, and since there is no refrigerant that bypasses the expander, efficient operation can be performed.

  In addition, although there is a case of heating operation, the operation is the same as that of the air conditioner shown in FIGS.

  Next, as a specific operation method of the heat exchanger bypass valve 23 and the pre-expansion valve 8, the control performed by the control device 15 will be described based on the flowchart shown in FIG.

  During operation of the refrigeration cycle device, the optimum high-pressure side pressure is not always constant, and is stored in advance as a table in the ROM or the like in the control device 15 based on the outside air during operation, the required load capacity, etc., and the target discharge temperature is determined. (Step 300). Next, the detected value (discharge temperature) (step 301) from the temperature sensor 16 is captured. The target discharge temperature is compared with the discharge temperature taken in step 301 (step 302).

  If the discharge temperature is lower than the target discharge temperature, the high-pressure side pressure tends to be lower than the optimum pressure, so it is first determined whether or not the heat exchanger bypass valve 23 is fully open (step 303). When the heat exchanger bypass valve 23 is fully open, the pre-expansion valve 8 is operated in the closing direction (step 304), the refrigerant flowing into the expander 9 is decompressed, the refrigerant density is reduced, and the high-pressure side pressure and discharge are reduced. Increase temperature. If the heat exchanger bypass valve 23 is not fully open, the heat exchanger bypass valve 23 is operated in the opening direction (step 305), the heat exchange completion in the internal heat exchanger 21 is increased, and the high pressure side pressure and discharge temperature are increased. To raise.

  On the other hand, when the discharge temperature is higher than the target discharge temperature, the high-pressure side pressure tends to be higher than the optimum pressure, so it is first determined whether or not the pre-expansion valve 8 is fully open (step 306). . When the pre-expansion valve 8 is fully open, the heat exchanger bypass valve 23 is operated in the closing direction (step 307), the amount of heat exchange in the internal heat exchanger 21 is increased, and the high-pressure side pressure and discharge temperature are decreased. Let If the pre-expansion valve 8 is not fully opened, the pre-expansion valve 8 is operated in the opening direction (step 308) so that the refrigerant flowing into the expander 9 is not decompressed so that the refrigerant density is not reduced. As a result, the high-pressure side pressure and the discharge temperature are reduced.

  After the above steps, the process returns to step 300 and thereafter repeats from step 300 to step 308, thereby performing control in which the heat exchanger bypass valve 23 and the pre-expansion valve 8 are linked as shown in FIG.

  As described above, in the air conditioning apparatus shown in FIGS. 5 to 7, in the refrigeration cycle apparatus using the expander that is difficult to maintain the optimum high-pressure side pressure due to the restriction of a constant density ratio, Regardless of whether the density ratio (DE / DC) in the actual operating state is smaller or larger than the design volume ratio (VC / VE) assumed at the time of designing, the opening operation of the heat exchanger bypass valve 23 and the pre-expansion valve 8 is controlled. Therefore, it is possible to operate without reducing the operation efficiency and capacity, and to ensure the reliability of the expander and compressor, because the power is reliably recovered without adjusting the desired high-pressure side pressure and bypassing the expander. An air conditioner that can be provided is provided.

  Also, there is a concern when the amount bypassing the expander is large, the expansion speed of the expander is low, the lubrication state at the sliding part deteriorates, the expansion further, the oil stays in the path of the expander, the exhaustion of the oil in the compressor, restart It is possible to reduce a decrease in reliability such as the start of stagnation of the refrigerant.

  The function is divided into a main compressor 20 having a drive source and a sub compressor 4 driven by the expansion power of the expander 9. Since structural design and functional design can also be divided, there are fewer design and manufacturing issues compared to a drive source / expander / compressor integrated unit.

  In addition, since the sub-compressor 4 that is recovered and driven by the expander 9 is used as a high-stage compressor, the refrigerant circulation amount is determined by the operating frequency and suction state of the main compressor 20 that is a low-stage compressor. There is an advantage that it is easy to control the cycle state.

Embodiment 3 FIG.
The air conditioner shown in FIG. 8 is the connection order of the main compressor 20 and the sub-compressor 4 as compared with the air conditioner shown in FIG. 5, the other configurations are the same, and the same functional parts are the same. A description is omitted with reference numerals. In the refrigerant circuit of FIG. 5, the refrigerant passes through the internal heat exchanger 21, the main compressor 20, the sub compressor 4, and the first four-way valve 5 in this order. However, in the air conditioner of FIG. 8, the refrigerant is the internal heat exchanger. 21, the sub compressor 4, the main compressor 20, and the first four-way valve 5 pass in this order.

  Next, regarding the operation at the time of operation of the refrigeration cycle apparatus configured as described above, the stroke volume of the sub compressor 4 is VC, the stroke volume of the expander 9 is VE, the inflow refrigerant density of the sub compressor 4 is DC, The inflow refrigerant density of the expander 9 will be described as DE.

Cooling operation with (DE / DC) ≈ (VC / VE) First, the cooling is such that the density ratio (DE / DC) in the actual operation state is substantially equal to the design volume ratio (VC / VE) assumed at the time of design. The case of driving will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 8, and the outdoor heat exchanger 6 functions as a radiator (condenser) and the indoor heat exchangers 12a and 12b function as an evaporator.

  The refrigerant flowing into the internal heat exchanger 21 is heated, flows into the sub-compressor 4 and becomes a medium-pressure refrigerant through a compression process, and flows into the main compressor 20 and further undergoes a compression process to become a high-pressure refrigerant. It passes through the first four-way valve 5 and is cooled by exchanging heat with the outside air in the outdoor heat exchanger. Next, it passes through the second four-way valve 7 and is cooled by the internal heat exchanger 21. The refrigerant that does not pass through the internal heat exchanger 21 passes through the heat exchange bypass flow path 22, is adjusted in flow rate by the heat exchange bypass valve 23, and merges with the refrigerant that has flowed out of the internal heat exchanger 21. Thereafter, it passes through the pre-expansion valve 8 and is expanded to a low pressure by the expander 9. Thereafter, the refrigerant passes through the second four-way valve 7 and the pre-expansion valve 8 and flows into the expander 9, and the refrigerant is depressurized from high pressure to low pressure to be in a low pressure two-phase state. After that, the second four-way valve 7 is branched and passes through the expansion valves 11a and 11b, and the indoor heat exchangers 12a and 12b absorb the heat from the room air to perform the cooling operation, and passes through the first four-way valve 5 and passes through the main compressor. Flows into 1.

Cooling operation with (DE / DC)> (VC / VE) Next, the density ratio (DE / DC) in the actual operation state is larger than the design volume ratio (VC / VE) assumed at the time of design. The case will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 8, and the outdoor heat exchanger 6 functions as a radiator (condenser) and the indoor heat exchangers 12a and 12b function as an evaporator. In this case, due to the restriction of a constant density ratio, the refrigeration cycle tries to balance in a state where the high-pressure pressure is reduced so that the inlet refrigerant density (DE) of the expander 9 becomes small. However, the operating efficiency is reduced when the high pressure is lower than the desired pressure.

  For this reason, if the heat exchanger bypass valve 23 is not fully open, the heat exchanger bypass valve 23 is operated in the opening direction to reduce the refrigerant passing through the internal heat exchanger 21, so that the heat exchange amount is reduced and the expander The inlet density of 9 is lowered and stabilized.

  Or if the heat exchanger bypass valve 23 is a full open state, the pre-expansion valve 8 will be operated in a closing direction, the refrigerant | coolant which flows in into the expander 9 will be expanded, and a refrigerant density will be reduced.

  By these operations, the high-pressure side pressure can be increased and adjusted to a desired pressure, and since there is no refrigerant that bypasses the expander, an efficient operation can be performed.

On the contrary, in the cooling operation with (DE / DC) <(VC / VE), the density ratio (DE / DC) in the actual operation state is smaller than the design volume ratio (VC / VE) assumed at the time of design. The case will be described. The first four-way valve 5 and the second four-way valve 7 are set as shown by the solid lines in FIG. 1, and the outdoor heat exchanger 6 functions as a radiator (condenser) and the indoor heat exchangers 12a and 12b function as an evaporator. In this case, due to the restriction of the constant density ratio, the refrigeration cycle tries to balance with the high pressure increased so that the inlet refrigerant density (DE) of the expander 9 is increased. However, the operating efficiency is reduced when the high pressure is higher than the desired pressure.

  For this reason, if the pre-expansion valve 8 is not fully opened, the pre-expansion valve 8 is operated in the opening direction so that the refrigerant flowing into the expander 9 is not expanded, and the refrigerant density is increased.

  Alternatively, if the pre-expansion valve 8 is fully open, the heat exchange bypass valve 23 is operated in the closing direction to increase the amount of refrigerant passing through the internal heat exchanger 21, so that the heat exchange amount increases and the inlet density of the expander 9 increases. The rise will rise and stabilize.

  By these operations, the high-pressure side pressure can be reduced and adjusted to a desired pressure, and since there is no refrigerant that bypasses the expander, efficient operation can be performed.

In addition to the heating operation, there is a case of the heating operation, but the operation is the same as that of the air conditioner of FIGS. Moreover, the control which the control apparatus 24 which is a concrete operation method of the heat exchanger bypass valve 23 and the pre-expansion valve 8 is the same as that of FIG. 6 and FIG.

  As described above, in this air conditioner, in the refrigeration cycle apparatus using an expander that is difficult to maintain the optimum high-pressure side pressure due to the restriction of the constant density ratio, in the actual operation state Regardless of whether the density ratio (DE / DC) is smaller or larger than the design volume ratio (VC / VE) assumed at the time of design, the desired high pressure side pressure can be determined by opening the heat exchange bypass valve 23 and the pre-expansion valve 8. The air conditioner that can be operated without lowering the operation efficiency and capacity, and that can ensure the reliability of the expander and compressor is provided. Is done.

  Also, there is a concern when the amount bypassing the expander is large, the expansion speed of the expander is low, the lubrication state at the sliding part deteriorates, the expansion further, the oil stays in the path of the expander, the exhaustion of the oil in the compressor, restart It is possible to reduce a decrease in reliability such as the start of stagnation of the refrigerant.

  The function is divided into a main compressor 20 having a drive source and a sub compressor 4 driven by the expansion power of the expander 9. Since structural design and functional design can also be divided, there are fewer design and manufacturing issues compared to a drive source / expander / compressor integrated unit.

  Further, since the sub-compressor 4 that is recovered and driven by the expander 9 is used as a low-compressor, the sub-compressor 4 has a low pressure, and there is a margin in strength design.

It is a refrigerant circuit figure showing one embodiment of the air harmony device of this invention. It is sectional drawing of the main compressor of the air conditioning apparatus shown in FIG. It is a flowchart which shows the operating method of the air conditioning apparatus shown in FIG. It is an operation | movement diagram of the control means of the air conditioning apparatus shown in FIG. It is a refrigerant circuit figure which shows another embodiment of the air conditioning apparatus of this invention. It is a flowchart which shows the operating method of the air conditioning apparatus shown in FIG. It is an operation | movement figure of the control means of the air conditioning apparatus shown in FIG. It is a refrigerant circuit figure which shows another embodiment of the air conditioning apparatus of this invention.

Explanation of symbols

  1, 20 main compressor, 2 compression bypass flow path, 3 compression bypass valve, 4 subcompressor, 5 first four-way valve, 6 outdoor heat exchanger, 7 second four-way valve, 8 pre-expansion valve, 9 expander, DESCRIPTION OF SYMBOLS 10 Drive shaft, 11a, 11b Indoor expansion valve, 12a, 12b Indoor heat exchanger, 13 Outdoor unit, 14a, 14b Indoor unit, 15, 24 Controller, 16, 17a, 17b, 18a, 18b, 19a, 19b Temperature sensor , 21 Internal heat exchanger, 22 Heat exchange bypass flow path, 23 Heat exchange bypass valve, 101 Shell, 102 Motor, 103 Shaft, 104 Swing scroll, 105 Fixed scroll, 106 Inflow piping, 107 Low pressure space, 108 Compression chamber, 109 compression chamber, 110 outflow port, 111 high pressure space, 112 outflow piping, 113 compression bypass port, 114 bypass piping.

Claims (7)

In an air conditioner in which a main compressor, a radiator, an expander, and an evaporator are connected in order,
A compression bypass passage for bypassing from the intermediate pressure of the compression process in the main compressor to after completion of the compression process;
A sub-compressor provided on the compression bypass flow path and connected to the expander by a drive shaft;
A compression bypass valve connected between the main compressor and the sub-compressor on the compression bypass flow path;
An air conditioner comprising: a control device that adjusts a high-pressure side pressure by changing an opening of the compression bypass valve.   The air conditioning apparatus according to claim 1, further comprising a pre-expansion valve that expands a refrigerant flowing into the expander in advance.   The said control apparatus changes the opening degree of the said compression bypass valve and the said pre-expansion valve based on the discharge temperature or superheat degree of the confluence | merging part of the said main compressor and the said sub compressor. The air conditioning apparatus described in 1.   The product of the ratio of the compression chamber volume immediately after the bypass passage conduction to the stroke volume in the main compressor and the built-in volume ratio of the sub-compressor substantially matches the built-in volume ratio of the main compressor. The air conditioning apparatus according to any one of claims 1 to 3, wherein: The main compressor, radiator, expander, and evaporator are connected in order,
A compression bypass passage for bypassing from the intermediate pressure of the compression process in the main compressor to after completion of the compression process;
A sub-compressor provided on the compression bypass flow path and connected to the expander by a drive shaft;
An operation method of an air conditioner including a compression bypass valve connected between the main compressor and the sub compressor on the compression bypass flow path,
A method of operating an air conditioner, wherein the opening of the compression bypass valve is changed to adjust the high-pressure side pressure. Providing a pre-expansion valve for pre-expanding the refrigerant flowing into the expander;
6. The air conditioner according to claim 5 , wherein the opening degrees of the compression bypass valve and the pre-expansion valve are changed based on a discharge temperature or a superheat degree of a joining portion of the main compressor and the sub compressor. How to operate the device. The product of the ratio of the compression chamber volume immediately after completion of bypass flow passage conduction to the stroke volume in the main compressor and the built-in volume ratio of the sub-compressor is approximately matched with the built-in volume ratio of the main compressor. how the operation of the air conditioner according to 6 claim 5 Ah Rui, wherein.

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