JP2012102968A - Refrigerating cycle device - Google Patents

Abstract

A refrigeration cycle apparatus capable of starting an expander and a sub-compressor more stably is provided.
A refrigeration cycle apparatus 1A includes a refrigerant circuit 2 including a sub compressor 31, a main compressor 32, a radiator, an expander 36, and an evaporator. The refrigerant circuit 2 is provided with a first control valve 41 and a second control valve 42 on the upstream side of the sub compressor 31 and the expander 36, respectively. An expansion valve 51 is provided in the first bypass passage 5 that bypasses the expander 36, and a bypass valve 61 is provided in the second bypass passage 6 that bypasses the sub compressor. Furthermore, a recirculation valve 71 is provided in the recirculation path 7 that connects a portion between the main compressor 32 and the radiator and a portion between the evaporator and the sub compressor 31 in the refrigerant circuit 2.
[Selection] Figure 1

Description

  The present invention relates to a refrigeration cycle apparatus.

  2. Description of the Related Art Conventionally, a refrigeration cycle apparatus including an expander that expands a refrigerant to recover power and a sub-compressor that preliminarily boosts the refrigerant upstream of the main compressor is known. In such a refrigeration cycle apparatus, the main compressor is driven by an electric motor, while the sub-compressor is connected to the expander by a transmission shaft, and is driven by power recovered from the refrigerant by the expander.

  By the way, in the configuration as described above, the start-up of the expander and the sub-compressor from the stopped state is performed only by starting the main compressor and creating a high-low pressure difference, so that the expander and the sub-compressor are stabilized. The problem is how to start it. As a countermeasure against this, for example, in Patent Document 1, a bypass path is provided in the refrigerant circuit, and the high-pressure refrigerant discharged from the main compressor at the time of startup is directly guided to the suction port of the sub compressor or the suction port of the expander, It is disclosed that the main compressor can suck the refrigerant to the discharge port of the sub compressor or the discharge port of the expander.

JP 2009-204201 A

  However, the countermeasure disclosed in Patent Document 1 is still insufficient to start the expander and the sub compressor stably. That is, the high-low pressure difference between the suction port and the discharge port of the expander and the sub-compressor gradually increases with the start of the main compressor, but the load that the transmission shaft is pressed against the bearing also increases accordingly. For this reason, depending on the stopped state of the expander and the sub-compressor, the starting torque generated from the high-low pressure difference between the suction port and the discharge port may not be able to overcome the maximum static frictional force. In addition, when the expander has a working chamber that expands the refrigerant by changing the volume, and the working chamber is filled with liquid refrigerant or lubricating oil, the hard-to-expand liquid rotates to increase the volume of the working chamber. It becomes an obstacle.

  An object of this invention is to provide the refrigerating-cycle apparatus which can start an expander and a subcompressor more stably in view of such a situation.

  In order to solve the above problems, the present invention provides a main compressor that compresses refrigerant, a radiator that dissipates the refrigerant compressed by the main compressor, and recovers power by expanding the refrigerant dissipated by the radiator. An expander that evaporates the refrigerant expanded in the expander, and a sub-compressor that is connected to the expander by a transmission shaft and pressurizes the refrigerant evaporated in the evaporator before being sucked into the main compressor , A first bypass passage provided in the refrigerant circuit so as to bypass the expander, and an expansion valve provided in the first bypass passage for decompressing the refrigerant radiated by the radiator A second bypass passage provided in the refrigerant circuit so as to bypass the sub-compressor, a bypass valve that permits or prohibits the flow of the refrigerant through the second bypass passage, and the main compression in the refrigerant circuit Machine and said Provided in the refrigerant circuit, a reflux path that communicates a portion between the heater and a portion between the evaporator and the sub-compressor, a reflux valve that permits or prohibits the flow of the refrigerant through the reflux path, and In addition, a first control valve that permits or prohibits the flow of refrigerant from the evaporator to the sub-compressor, and permits or prohibits the flow of refrigerant from the radiator to the expander provided in the refrigerant circuit. A refrigeration cycle device comprising a second control valve.

  According to the above configuration, by controlling the valve, the pressure before and after the expander and the sub-compressor is once equalized to a low pressure at the time of startup, and then the suction side of the expander and the sub-compressor can be set to a high pressure. . By equalizing the pressure before and after the expander and the sub-compressor to a low pressure, the maximum static frictional force can be reduced by weakening the load that the transmission shaft is pressed against the bearing. Moreover, even if the working chamber of the expander is filled with liquid refrigerant or lubricating oil, the liquid can be sucked out. After that, by increasing the suction side of the expander and the sub compressor, a strong impulse (force × time: N · s) can be given to both the expander and the sub compressor. By these actions, the expander and the sub-compressor can be started much more stably than before.

The block diagram of the refrigerating-cycle apparatus which concerns on 1st embodiment of this invention. Configuration diagram of a power recovery unit and a compression unit used in the refrigeration cycle apparatus of FIG. Flow chart of start-up operation in the first embodiment Configuration diagram of alternative power recovery unit and compression unit Configuration of another alternative power recovery unit and compression unit Configuration diagram of a modified refrigeration cycle apparatus Configuration of refrigeration cycle apparatus according to another modification The block diagram of the refrigerating air-conditioning apparatus which concerns on 2nd embodiment of this invention. Flow chart of start-up operation in the second embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the following embodiment.

(First embodiment)
FIG. 1 shows a refrigeration cycle apparatus 1A according to Embodiment 1 of the present invention. The refrigeration cycle apparatus 1A is configured as an air conditioner, and can be switched between a heating operation and a cooling operation. In addition, the refrigerating cycle apparatus of this invention is not limited to an air conditioner, For example, you may be comprised as a warm water generator with the flow direction of the refrigerant | coolant used for a hot water heater etc. unchanged.

  The refrigeration cycle apparatus 1A includes a refrigerant circuit 2 that circulates refrigerant and a controller 4. The refrigerant circuit 2 includes a sub compressor 31, a main compressor 32, a first four-way valve 33, an indoor heat exchanger 34, a second four-way valve 35, an expander 36, and an outdoor heat exchanger 37. As the refrigerant, for example, hydrofluorocarbon can be used. In the hot water generator described above, carbon dioxide may be used as the refrigerant.

  The discharge port of the sub compressor 31 and the suction port of the main compressor 32 are connected to each other by the flow path 21. The first four-way valve 33 is connected to the discharge port of the main compressor 32, the indoor heat exchanger 34, the outdoor heat exchanger 37, and the suction port of the sub compressor by flow paths 22, 23, 28, and 29. Yes. The second four-way valve 35 is connected to the indoor heat exchanger 34, the suction port of the expander 36, the discharge port of the expander 36, and the outdoor heat exchanger 37 by flow paths 24, 25, 26, and 27. .

  The first four-way valve 33 and the second four-way valve 35 are controlled by the controller 4 so that the direction of the refrigerant flowing through the refrigerant circuit 2 is switched to the direction of the solid arrow during the heating operation, and the broken arrow is used during the cooling operation. Switch to the direction. The direction of the solid line arrow is a direction in which the refrigerant discharged from the main compressor 31 is guided to the indoor heat exchanger 34 and the refrigerant discharged from the expander 36 is guided to the outdoor heat exchanger 37. The direction of the broken line arrow is the direction in which the refrigerant discharged from the main compressor 31 is guided to the outdoor heat exchanger 37 and the refrigerant discharged from the expander 36 is guided to the indoor heat exchanger 34. That is, during the heating operation, the indoor heat exchanger 34 functions as a radiator and the outdoor heat exchanger 37 functions as an evaporator. In the cooling operation, the outdoor heat exchanger 37 functions as a radiator and the indoor heat exchanger 34 functions as an evaporator.

  The flow path 22 that connects the first four-way valve 33 to the discharge port of the main compressor 32 is always between the main compressor 32 and the radiator regardless of the heating operation and the cooling operation. The flow path 29 that connects the valve 33 to the suction port of the sub-compressor 31 is always between the evaporator and the sub-compressor 31 regardless of the heating operation and the cooling operation. The flow path 25 that connects the second four-way valve 35 to the inlet of the expander 36 is always between the radiator and the expander 36 regardless of the heating operation and the cooling operation, and the second four-way valve 35. Is connected between the expander 36 and the evaporator regardless of the heating operation and the cooling operation.

  In the following, unless otherwise specified, the terms heat radiator and evaporator will be used instead of the indoor heat exchanger 34 and the outdoor heat exchanger 37, and the heating operation and the cooling operation will be described without distinction.

  The main compressor 32 is driven by an electric motor 45. The main compressor 32 and the electric motor 45 are accommodated in the first sealed container 13 as shown in FIG. Inside the first airtight container 13, a first oil reservoir 13 a is formed by storing lubricating oil, and an upper space facing the first oil reservoir 13 a is formed. The main compressor 32 sucks and compresses the refrigerant from the flow path 21 through the suction port, and discharges the compressed refrigerant to the upper space of the first sealed container 13 through the discharge port. The refrigerant discharged into the upper space of the first sealed container 13 is discharged to the outside through a pipe 22a that passes through the first sealed container 13 and opens into the upper space. That is, the first hermetic container 13 and the pipe 22a constitute the flow path 22 described above. The refrigerant discharged from the main compressor 32 flows into the heat radiator (the indoor heat exchanger 34 or the outdoor heat exchanger 37), where it exchanges heat with air to radiate heat.

  The expander 36 is connected to the sub compressor 31 by the transmission shaft 11. The expander 36 and the sub compressor 36 constitute a power recovery mechanism. As shown in FIG. 2, the expander 36 and the sub compressor 31 are accommodated in the second sealed container 12. A second oil reservoir 12a is formed inside the second sealed container 12 by storing lubricating oil. The expander 36 sucks the refrigerant flowing out of the radiator from the flow path 25 through the suction port, and expands the sucked refrigerant. At this time, the expander 36 recovers power from the expanding refrigerant, and drives the sub-compressor 31 with the recovered power. The expander 36 discharges the expanded refrigerant to the flow path 26 through the discharge port. The refrigerant discharged from the expander 36 flows into the evaporator (outdoor heat exchanger 37 or indoor heat exchanger 34), where it evaporates by exchanging heat with air.

  As the expander 36, for example, a scroll expander, a rotary expander, or a fluid pressure motor expander can be used. The fluid pressure motor type expander does not include an expansion step, and performs a process of sucking the refrigerant and a process of discharging the sucked refrigerant substantially continuously, so that the suction side and the discharge side It is a fluid machine which expands a refrigerant by the pressure difference of. The scroll expander and the rotary expander have a working chamber that expands the refrigerant by changing the volume.

  The sub-compressor 31 sucks the refrigerant flowing out of the evaporator from the flow path 29 through the suction port to increase the pressure, and discharges the pressurized refrigerant to the flow channel 21 through the discharge port. That is, the sub compressor 31 preliminarily boosts the refrigerant sucked into the main compressor 32.

  As the subcompressor 31, a scroll compressor, a rotary compressor, or a fluid pressure motor compressor can be used. Note that the fluid pressure motor type compressor does not include the process of compressing the refrigerant, and performs the process of sucking the refrigerant and the process of discharging the sucked refrigerant substantially continuously, thereby discharging the suction side and the discharge side. It is a compressor which pressurizes the refrigerant by the pressure difference with the side. The scroll compressor and the rotary compressor have a working chamber that compresses the refrigerant by changing the volume.

  In the present embodiment, the second sealed container 12 is configured so that the internal pressure becomes equal to the pressure of the refrigerant discharged from the main compressor 32. Specifically, the second sealed container 12 is connected to the first sealed container 13 by the oil equalizing pipe 14, and the second oil reservoir 12a communicates with the first oil reservoir 13a.

  Further, in the present embodiment, the first control valve 41 is provided in the flow path 29 that connects the first four-way valve 33 to the suction port of the sub-compressor 31, and the second four-way valve 35 is disposed in the suction of the expander 36. A second control valve 42 is provided in the flow path 25 connected to the mouth. The first control valve 41 permits or prohibits the inflow of refrigerant from the evaporator to the sub compressor 31, and the second control valve 42 permits or prohibits the inflow of refrigerant from the radiator to the expander 36.

  The refrigerant circuit 2 is provided with a first bypass passage 5 so as to bypass the expander 36 and a second bypass passage 6 so as to bypass the sub compressor 31. The first bypass path 5 branches from the flow path 25 on the upstream side of the second control valve 42 and is connected to the flow path 26. In addition, the first bypass path 5 is provided with an expansion valve 51 that depressurizes the refrigerant radiated by the radiator. The second bypass path 6 branches from the flow path 29 on the upstream side of the first control valve 41 and is connected to the flow path 21. The second bypass passage 6 is provided with a bypass valve 61 that permits or prohibits the circulation of the refrigerant through the second bypass passage 6.

  Further, the refrigerant circuit 2 is provided with a reflux path 7 that connects the flow path 22 and the downstream side portion of the flow path 29 with respect to the first control valve 41. The reflux path 7 is provided with a reflux valve 71 that permits or prohibits the circulation of the refrigerant through the reflux path 7.

  In the present embodiment, on-off valves are employed as the first control valve 41, the second control valve 42, the bypass valve 61 and the reflux valve 71. However, instead of the on-off valve, a flow rate adjusting valve capable of adjusting the opening degree from fully closed to fully open can be employed.

  The refrigeration cycle apparatus 1A includes a pressure sensor 47 provided in the flow path 22 for detecting the pressure (high pressure) of the refrigerant discharged from the main compressor 32, the expander 36, and the sub compressor 31 (that is, power). And an activation detector 46 for detecting the activation of the recovery mechanism.

  When the power recovery mechanism is activated, the transmission shaft 11 starts to rotate, and a temperature difference and a pressure difference are generated between the refrigerant at the suction port of the expander 36 and the refrigerant at the discharge port. Therefore, a temperature difference measuring device that measures the temperature difference between the refrigerant temperature at the suction port of the expander 36 and the refrigerant temperature at the discharge port of the expander 36 can be used as the activation detector 46. Instead of the temperature difference measuring device, a pressure difference measuring device that measures the pressure difference between the refrigerant pressure at the suction port of the expander 36 and the refrigerant pressure at the discharge port of the expander 36 may be used. Further, since the power recovery mechanism is started at a substantially constant time after the main compressor 32 is started, a timer that measures an elapsed time from the start of starting the main compressor 32 may be used as the start detector 46. it can.

  The controller 4 controls the four-way valves 33 and 35, the electric motor 45, and the various valves 41, 42, 51, 61, and 71 described above. The controller 4 first performs a start-up operation for starting up the refrigeration cycle apparatus 1A based on the detection results of the pressure sensor 47 and the start-up detector 46, and then shifts to a steady operation. Hereinafter, the starting operation performed by the controller 4 will be described in detail with reference to the flowchart of FIG.

  First, when a command to start the operation of the refrigeration cycle apparatus 1A (for example, turning on the start switch) is given, the controller 4 closes the reflux valve 71, opens the bypass valve 61, and opens the expansion valve 51 to a predetermined opening degree. (Step S11). At this time, the first control valve 41 and the second control valve 42 may be closed or opened. In this state, the main compressor 32 is started (step S12). As a result, the refrigerant flows through the route passing through the main compressor 32, the radiator, the expansion valve 51, and the evaporator, and an appropriate pressure difference is created between the high pressure side and the low pressure side of the refrigeration cycle.

  Next, the controller 4 detects the high pressure P with the pressure sensor 47 (step S13), and determines whether or not the detected high pressure P is within a predetermined range (P1 to P2) (step S14). If No in step S14, the state is maintained, and if Yes in step S14, the process proceeds to step S15 and the first control valve 41 and the second control valve 42 are closed.

  Here, the predetermined range (P1 to P2) is a range determined by the target discharge pressure of the main compressor 32, and is, for example, 1.7 to 3.5 MPa.

  Thereafter, the controller 4 maintains the state until a predetermined time elapses after the first control valve 41 and the second control valve 42 are closed (No in step S16). That is, the controller 4 performs a first operation for operating the main compressor 32 for a predetermined period defined by a predetermined time. By this first operation, the pressure before and after the expander 36 and the pressure before and after the sub compressor 31 are equalized to a low pressure. This is because in the expander 36 and the sub compressor 31, the suction port and the discharge port communicate with each other through a minute gap inside. As a result, the maximum static frictional force can be reduced by weakening the load that the transmission shaft 11 is pressed against the bearing. Furthermore, when the working chamber of the expander 36 is filled with liquid refrigerant or lubricating oil, the liquid can be sucked out by using the suction by the main compressor 32 by the first operation.

  Here, the predetermined time in step S16 is a time sufficient for the pressure before and after the expander 36 and the pressure before and after the sub compressor 31 to be equal. Such a time can be determined in advance by experiments or the like.

  When a predetermined time elapses after the first control valve 41 and the second control valve 42 are closed (Yes in step S16), the controller 4 fully closes the expansion valve 51 (step S17), the second control valve 42 and the reflux The valve 71 is opened (steps S18 and S19), and the second operation is performed. Steps S17 to S19 are preferably performed in this order.

  First, the second control valve 42 is opened to guide the high-pressure refrigerant discharged from the main compressor 32 to the expander 36. When the sub-compressor 31 is a single-stage rotary compressor, the refrigerant may blow through depending on the stop position of the piston, and there is a case where no pressure is applied to the piston and no starting torque is generated on the transmission shaft 11. In contrast, the high-pressure refrigerant is first guided to the expander 36 that can generate a starting torque regardless of the stop position, thereby increasing the certainty of starting. Since the pressure before and after the expander 36 is equalized to a low pressure by the first operation, a strong impulse can be given to the expander 36 by this process (step S18).

  Subsequently, the high-pressure refrigerant discharged from the main compressor 32 is guided to the sub compressor 31 by opening the reflux valve 71. Thereby, a strong impulse can also be given to the sub compressor 31. When the sub-compressor 31 is activated by the supply of the high-pressure refrigerant, the sub-compressor 31 functions as an expander or a fluid pressure motor because the pressure on the discharge side is lower than the pressure on the suction side. Therefore, an additional starting torque is given to the transmission shaft 11.

  With the above-described actions, the power recovery mechanism can be activated much more stably than before.

  Thereafter, the controller 4 determines whether or not the power recovery mechanism is activated by the activation detector 46. As the activation detector 46, three modes are conceivable as described above.

  When the activation detector 46 is a temperature difference measuring instrument that measures the temperature difference of the refrigerant between the suction port and the discharge port of the expander 36, the expander when the expander 36 is activated, which is experimentally determined. The temperature difference ΔT of the refrigerant between the suction port and the discharge port is input to the controller 4 in advance as a threshold value. The controller 4 can determine that the power recovery mechanism has been activated when the temperature difference measured by the temperature difference measuring instrument exceeds ΔT. Alternatively, the controller 4 increases the temperature difference measured by the temperature difference measuring instrument per unit time (measured by the temperature difference measuring instrument from the temperature difference measured by the temperature difference measuring instrument when the unit time goes back). When the value obtained by subtracting the current temperature difference) exceeds a predetermined threshold value, it can also be determined that the power recovery mechanism has been activated.

  When the activation detector 46 is a pressure difference measuring device that measures the pressure difference of the refrigerant between the suction port and the discharge port of the expander 36, the expander 36 obtained when the expander 36 is activated is determined experimentally. The pressure difference ΔP of the refrigerant between the suction port and the discharge port is previously input to the controller 4 as a threshold value. The controller 4 can determine that the power recovery mechanism has been activated when the pressure difference measured by the pressure difference measuring instrument exceeds ΔP. Alternatively, the controller 4 increases the pressure difference measured by the pressure difference measuring instrument per unit time (measured by the pressure difference measuring instrument from the pressure difference measured by the pressure difference measuring instrument when the unit time goes back). When the value obtained by subtracting the current pressure difference) exceeds a predetermined threshold, it can also be determined that the power recovery mechanism has been activated.

  When the activation detector 46 is a timer, the time t from the start of activation of the main compressor 32 until the activation of the power recovery mechanism is input to the controller 4 as a threshold value in advance. The controller 4 transmits a control signal to the electric motor 45 that drives the main compressor 32 and starts measuring time. When the elapsed time measured by the timer exceeds t, the controller 4 determines that the power recovery mechanism has started. be able to.

  When the activation detector 46 detects the activation of the power recovery mechanism (Yes in step S20), the controller 4 opens the first control valve 41 to supply the low-pressure refrigerant to the sub compressor 31, and the recirculation valve 71 is turned on. Close (step S22). By this step, the sub compressor 31 does not function as the above-described expander or fluid pressure motor but performs its original function.

  Thereafter, the controller 4 closes the bypass valve 61 (step S23). As a result, all the refrigerant sucked by the main compressor 32 passes through the sub-compressor 31. The subcompressor 31 boosts the refrigerant by the power recovered by the expander 36, and the main compressor 32 sucks the boosted refrigerant, thereby reducing the driving force of the electric motor 45 that drives the main compressor 32.

  If the power recovery mechanism has not started (No in step S20), the controller 4 closes the recirculation valve 71, opens the expansion valve 51 to a predetermined opening again (step S21), and returns to step 13. That is, the controller 4 repeats the first operation and the second operation described above until the activation detector 46 detects the activation of the power recovery mechanism. Thereby, since an impulse can be repeatedly given to a power recovery mechanism, a power recovery mechanism can be started reliably.

<Modification>
In the said embodiment, the 2nd airtight container 12 is comprised so that an internal pressure may become equal to the pressure of the refrigerant | coolant discharged from the main compressor 32. FIG. That is, since the amount of lubricating oil in both the sealed containers 12 and 13 is automatically balanced through the oil equalizing pipe, the amount of lubricating oil can be easily adjusted.

  However, the second airtight container 12 may be configured such that the internal pressure becomes equal to the pressure of the refrigerant discharged from the sub compressor 31. In order to realize this, for example, a configuration as shown in FIG.

  In the configuration shown in FIG. 4, the oil equalizing pipe 14 is provided with an on-off valve 15. Further, an upper space facing the second oil reservoir 12a is formed inside the second sealed container 12. The sub compressor 31 discharges the pressurized refrigerant into the upper space of the second sealed container 12 through the discharge port. The refrigerant discharged into the upper space of the second sealed container 12 is discharged to the outside through a pipe 21a that passes through the second sealed container 12 and opens into the upper space. Thus, the flow path 21 may be comprised by the 2nd airtight container 12 and the piping 21a.

  In the configuration shown in FIG. 4, the on-off valve 15 is closed when the refrigeration cycle apparatus 1A is in operation. Thereby, the pressure inside the second sealed container 12 becomes equal to the pressure of the refrigerant discharged from the sub compressor 31. With such a configuration, for example, when at least one of the expander 36 and the sub-compressor 31 is a rotary type, the back pressure of the vane can be reduced as compared with the above embodiment. Frictional resistance can be reduced.

  When the refrigeration cycle apparatus 1A is stopped, the on-off valve 15 is opened to balance the amount of lubricating oil in both the sealed containers 12 and 13.

  Alternatively, as shown in FIG. 5, the inside of the second sealed container 12 may be partitioned into a first space 12 </ b> A that surrounds the expander 36 and a second space 12 </ b> B that surrounds the sub compressor 31 by the partition member 16. The second sealed container 12 has a pressure in the first space 12A equal to a pressure of the refrigerant discharged from the main compressor 12 and a pressure in the second space 12B of the refrigerant discharged from the sub compressor 31. You may be comprised so that it may become equal to a pressure. With such a configuration, both the advantages of the configuration shown in FIG. 2 and the advantages of the configuration shown in FIG. 4 can be obtained.

  Further, when both the expander 36 and the sub compressor 31 are rotary, and the suction volume of the sub compressor 31 is larger than that of the expander 36, the friction resistance due to the vanes in the sub compressor 31 is large, and the power recovery mechanism May interfere with the start-up. In this case, according to the configuration shown in FIG. 5, the frictional resistance on the subcompressor 31 side can be reduced while balancing the amount of lubricating oil with the first hermetic container 13 on the expander 36 side.

  In the above embodiment, the main compressor 32 is operated with the first control valve 41, the second control valve 42 and the reflux valve 71 closed, the bypass valve 61 opened, and the expansion valve 51 opened to a predetermined opening. The predetermined period in the first operation to be performed is until the predetermined time elapses after the first control valve 41 and the second control valve 42 are closed. However, the predetermined period in the first operation is not limited to this.

  For example, as shown in FIG. 6, the flow path 25 is provided with a pressure sensor 48 that detects the pressure of the refrigerant in the portion between the second control valve 42 and the expander 36 in the refrigerant circuit 2, and a predetermined period in the first operation. Alternatively, the first control valve 41 and the second control valve 42 may be closed until the pressure detected by the pressure sensor 48 falls below a predetermined value. That is, when the first control valve 41 and the second control valve 42 are also opened in step S11, the suction side of the expander 36 is once at a high pressure until step S15, so that it replaces step S16 in the flowchart shown in FIG. Thus, a step of determining whether or not the pressure detected by the pressure sensor 48 has become a predetermined value or less may be employed.

  Alternatively, instead of the pressure sensor 48, a temperature sensor that detects the temperature of the refrigerant in the portion of the refrigerant circuit 2 between the second control valve 42 and the expander 36 can be used.

  Moreover, in the said embodiment, although the 1st control valve 41 and the bypass valve 61 were the on-off valves provided in each of the flow path 29 and the 2nd bypass path 6, as a 1st control valve and a bypass valve of this invention, For example, as shown in FIG. 7, it is also possible to use a single three-way valve 43 provided at a position where the second bypass path 6 branches from the flow path 29. However, if the first control valve 41 and the bypass valve 61 are separate as in the above-described embodiment, it is preferable in that it is possible to perform flexible control such as closing the bypass valve 61 slightly after the first control valve 41 is closed. .

(Second embodiment)
Next, with reference to FIG.8 and FIG.9, the refrigerating-cycle apparatus 1B which concerns on 2nd embodiment of this invention is demonstrated.

  As shown in FIG. 8, the refrigeration cycle apparatus 1B according to the second embodiment is simply the addition of a short circuit 8 and a short circuit valve 81 to the refrigeration cycle apparatus 1A according to the first embodiment. It is the same as apparatus 1A. Below, the short circuit 8 and the short circuit valve 81 are demonstrated in detail, and the description about another part is abbreviate | omitted.

  The short-circuit path 8 connects the flow path 22 and the downstream portion of the flow path 25 with respect to the second control valve 42. In the present embodiment, one end of the short circuit 8 is connected to the upstream side of the recirculation valve 71 in the recirculation path 7, and the short circuit 8 communicates with the flow path 22 via the recirculation path 7. However, one end of the short circuit 8 may be directly connected to the flow path 22.

  The short circuit 8 is provided with a short circuit valve 81 that permits or prohibits the flow of the refrigerant through the short circuit 8. In this embodiment, an on-off valve is employed as the short-circuit valve 81, but a flow rate adjustment valve capable of adjusting the opening degree from fully closed to fully open can also be employed.

  The start-up operation performed by the controller is almost the same as that of the first embodiment, but in the second embodiment, instead of opening the second on-off valve 42 in the second operation, the short-circuit valve 81 is opened, and the power recovery mechanism is started. The valve 81 is closed and the second on-off valve 42 is opened. When the refrigeration cycle involves a gas-liquid two-phase change, the refrigerant that has passed through the radiator is a liquid phase or a gas-liquid two-phase containing a large amount of liquid, and therefore when the refrigerant that has passed through the radiator is supplied to the expander 36, Lubricating oil in sliding parts such as bearings is washed away, and frictional resistance increases. On the other hand, in the second embodiment, the power recovery mechanism is started more stably by supplying only the gas-phase refrigerant discharged from the main compressor 32 through the short-circuit valve 81 to the expander 36 in the second operation. be able to.

  Next, the starting operation performed by the controller 4 will be described in detail with reference to the flowchart of FIG.

  First, when an instruction to start the operation of the refrigeration cycle apparatus 1A (for example, turning on the start switch) is given, the controller 4 closes the reflux valve 71, opens the bypass valve 61, and expands the expansion valve 51 in step S31. Is opened to a predetermined opening, and the short-circuit valve 81 is closed. Steps S32 to S36 (steps including the first operation) are the same as steps S12 to S16 in FIG. The effect | action by 1st operation is the same as 1st embodiment.

  When the answer is Yes in step S36, the controller 4 fully closes the expansion valve 51 (step S37), opens the short-circuit valve 81 and the reflux valve 71 (steps S38 and S39), and performs the second operation. Steps S37 to S39 are preferably performed in this order.

  First, the high-pressure refrigerant discharged from the main compressor 32 is guided to the expander 36 by opening the short-circuit valve 81. When the sub-compressor 31 is a single-stage rotary compressor, the refrigerant may blow through depending on the stop position of the piston, and there is a case where no pressure is applied to the piston and no starting torque is generated on the transmission shaft 11. In contrast, the high-pressure refrigerant is first guided to the expander 36 that can generate a starting torque regardless of the stop position, thereby increasing the certainty of starting. Since the pressure before and after the expander 36 is equalized to a low pressure by the first operation, a strong impulse can be given to the expander 36 by this process (step S38). Furthermore, in the second embodiment, since the gas-phase refrigerant that does not pass through the radiator is supplied to the expander 36, the above-described effects can be obtained.

  Subsequently, the high-pressure refrigerant discharged from the main compressor 32 is guided to the sub compressor 31 by opening the reflux valve 71. Thereby, a strong impulse can also be given to the sub compressor 31. When the sub-compressor 31 is activated by the supply of the high-pressure refrigerant, the sub-compressor 31 functions as an expander or a fluid pressure motor because the pressure on the discharge side is lower than the pressure on the suction side. Therefore, an additional starting torque is given to the transmission shaft 11.

  Thereafter, when the activation detector 46 detects the activation of the power recovery mechanism (Yes in step S40), the controller 4 opens the first control valve 41 to supply the low-pressure refrigerant to the sub-compressor 31, and the recirculation valve. 71 is closed (step S42). By this step, the sub compressor 31 does not function as the above-described expander or fluid pressure motor but performs its original function. Next, the controller 4 opens the second on-off valve 42 and closes the short-circuit valve 81 (step S43). Finally, the controller 4 closes the bypass valve 61 (step S44).

  If the power recovery mechanism has not started (No in step S20), the controller 4 closes the recirculation valve 71 and the short-circuit valve 41 and opens the expansion valve 51 to a predetermined opening again (step S21). Return to 13. That is, the controller 4 repeats the first operation and the second operation described above until the activation detector 46 detects the activation of the power recovery mechanism. Thereby, since an impulse can be repeatedly given to a power recovery mechanism, a power recovery mechanism can be started reliably.

  Needless to say, the modification described in the first embodiment is also applicable to the second embodiment.

  A refrigeration cycle apparatus according to the present invention includes a main compressor, a sub-compressor that preliminarily boosts a refrigerant sucked into the main compressor, and an expander connected to the sub-compressor by a transmission shaft. In the apparatus, it is useful in that it is possible to realize more stable self-sustained activation of the expander and the sub-compressor without rotating the transmission shaft with an electric motor.

DESCRIPTION OF SYMBOLS 1A, 1B Refrigeration cycle apparatus 11 Transmission shaft 12 2nd airtight container 13 1st airtight container 16 Partition member 2 Refrigerant circuit 31 Subcompressor 32 Main compressor 33,35 Four-way valve 34 Indoor heat exchanger 36 Expander 37 Outdoor heat exchange 4 Controller 41 First control valve 42 Second control valve 46 Start detector 5 First bypass path 51 Expansion valve 6 Second bypass path 61 Bypass valve 7 Return path 71 Return valve 8 Short path 81 Short circuit valve

Claims (15)

A main compressor that compresses the refrigerant, a radiator that dissipates the refrigerant compressed by the main compressor, an expander that recovers power by expanding the refrigerant that has dissipated heat by the radiator, and a refrigerant expanded by the expander A refrigerant circuit including an evaporator to be evaporated, and a sub-compressor that is connected to an expander by a transmission shaft and pressurizes the refrigerant evaporated in the evaporator before being sucked into the main compressor;
A first bypass path provided to bypass the expander in the refrigerant circuit;
An expansion valve that is provided in the first bypass path and depressurizes the refrigerant radiated by the radiator;
A second bypass path provided in the refrigerant circuit to bypass the sub-compressor;
A bypass valve that permits or prohibits the circulation of the refrigerant through the second bypass path;
A reflux path connecting a portion between the main compressor and the radiator and a portion between the evaporator and the sub compressor in the refrigerant circuit;
A reflux valve that permits or prohibits the circulation of the refrigerant through the reflux path;
A first control valve provided in the refrigerant circuit, which permits or prohibits the inflow of refrigerant from the evaporator to the sub-compressor;
A second control valve provided in the refrigerant circuit, which permits or prohibits the inflow of refrigerant from the radiator to the expander;
A refrigeration cycle apparatus comprising: A short circuit that communicates a portion between the main compressor and the radiator and a portion between the second control valve and the expander in the refrigerant circuit;
The refrigeration cycle apparatus according to claim 1, further comprising: a short-circuit valve that permits or prohibits the circulation of the refrigerant through the short-circuit path.   During the start-up operation, the first compressor, the second valve, and the reflux valve are closed, the bypass valve is opened, and the expansion valve is opened to a predetermined opening, and the main compressor is opened for a predetermined period. The refrigeration cycle apparatus according to claim 1, further comprising a controller that performs a second operation of fully closing the expansion valve and opening the second control valve and the reflux valve after performing the first operation to be operated. Further comprising an activation detector for detecting activation of the expander and the sub-compressor;
The refrigeration according to claim 3, wherein the controller closes the recirculation valve and the bypass valve and opens the first control valve when the activation detector detects activation of the expander and the sub compressor. Cycle equipment.   During the start-up operation, the main control valve is closed with the first control valve, the second control valve, the reflux valve, and the short-circuit valve, the bypass valve is opened, and the expansion valve is opened to a predetermined opening. The refrigeration cycle apparatus according to claim 2, further comprising a controller that performs a second operation of fully closing the expansion valve and opening the short-circuit valve and the reflux valve after performing a first operation for operating the machine for a predetermined period. . Further comprising an activation detector for detecting activation of the expander and the sub-compressor;
The controller closes the reflux valve and the bypass valve and opens the first control valve and the second control valve when the activation detector detects activation of the expander and the sub compressor. Item 6. The refrigeration cycle apparatus according to Item 5.   7. The controller according to claim 3, wherein the controller repeats the first operation and the second operation until the activation detector detects activation of the expander and the sub compressor. 8. Refrigeration cycle equipment.   The refrigeration cycle apparatus according to any one of claims 3 to 7, wherein the predetermined period is from when the first control valve and the second control valve are closed until a predetermined time elapses.   The predetermined period is from when the first control valve and the second control valve are closed until the temperature or pressure of the refrigerant in the portion of the refrigerant circuit between the second control valve and the expander falls below a predetermined value. The refrigeration cycle apparatus according to any one of claims 3 to 7, wherein The activation detector is a timer that measures an elapsed time from the start of activation of the main compressor,
The refrigeration cycle apparatus according to claim 4 or 6, wherein the controller determines that the expander and the sub compressor are started when an elapsed time measured by the timer exceeds a predetermined threshold. The activation detector is a temperature difference measuring device that measures the temperature difference between the refrigerant temperature at the inlet of the expander and the refrigerant temperature at the outlet of the expander,
The controller is configured such that when the temperature difference measured by the temperature difference measuring instrument exceeds a predetermined threshold, or the increase width per unit time of the temperature difference measured by the temperature difference measuring instrument exceeds a predetermined threshold. The refrigeration cycle apparatus according to claim 4 or 6, wherein it is sometimes determined that the expander and the sub compressor are started. The activation detector is a pressure difference measuring device that measures a pressure difference between a refrigerant pressure at an inlet of the expander and a refrigerant pressure at an outlet of the expander,
The controller is configured such that when the pressure difference measured by the pressure difference measuring instrument exceeds a predetermined threshold, or the increment of the pressure difference measured by the pressure difference measuring instrument per unit time exceeds a predetermined threshold. The refrigeration cycle apparatus according to claim 4 or 6, wherein it is sometimes determined that the expander and the sub compressor are started. Further comprising a sealed container for accommodating the expander and the sub-compressor;
The refrigeration cycle apparatus according to any one of claims 1 to 12, wherein the sealed container is configured so that an internal pressure thereof is equal to a pressure of a refrigerant discharged from the main compressor. Further comprising a sealed container for accommodating the expander and the sub-compressor;
The refrigeration cycle apparatus according to any one of claims 1 to 12, wherein the sealed container is configured such that an internal pressure is equal to a pressure of a refrigerant discharged from the sub-compressor. Further comprising a sealed container for accommodating the expander and the sub-compressor;
The sealed container is partitioned into a first space surrounding the expander by a partition member and a second space surrounding the sub-compressor, and a pressure of the refrigerant discharged from the main compressor is a pressure in the first space. The refrigeration cycle apparatus according to any one of claims 1 to 12, wherein the pressure in the second space is equal to the pressure of the refrigerant discharged from the sub-compressor. .

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