JP2019045002A - Control method of heat pump - Google Patents

Abstract

To reduce the imbalance of a supply amount of refrigerator oil between a plurality of compressors when the shortage of the refrigerator oil occurs in a part of a plurality of the compressors which constitute a heat pump for use in, for example, an air conditioner or the like.SOLUTION: A heat pump comprises a temperature sensor for detecting a detection discharge temperature being a value having a correlation with a temperature of a heat medium discharged from an operating compressor being a compressor which is in an operation out of a plurality of the compressors. When it is determined that a state that a difference of overheat degrees of the heat medium between the compressor whose overheat degree being a value corresponding to a degree of the overheat of the heat medium which is introduced on the basis of the detection discharge temperature is the highest, and a compressor whose overheat degree is the lowest out of a plurality of the operating compressors is larger than a prescribed threshold is continued over a prescribed period, a ratio of the discharge amount of the heat medium from the operating compressor whose overheat degree occupied in a total discharge amount being a total sum of the discharge amount of the heat medium from a plurality of the operating compressors is increased.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a heat pump control method. More specifically, the present invention relates to a heat pump control method capable of reducing imbalance in the amount of supply of refrigeration oil among a plurality of compressors constituting a heat pump used in, for example, an air conditioner or the like.

  In the heat pump, continuing to supply the compressor with the proper amount of refrigeration oil is essential for ensuring the sealing performance (air tightness) in the compression stroke of the heat medium and the lubricity in the sliding portion of the compressor. If an appropriate amount of refrigeration oil is not supplied to the compressor, problems such as sealing failure and lubrication failure may occur in the compressor, which may lead to problems such as the heat medium being repeatedly compressed and overheating or the compressor being damaged. There is.

  Therefore, in the relevant technical field, there is known a heat pump which recovers refrigeration oil (oil) contained in a refrigerant discharged from a compressor by an oil separator and returns the recovered refrigeration oil to the compressor. In such a heat pump, for example, if it becomes difficult to return the refrigerator oil to the compressor due to damage or clogging of the oil return flow path for returning the refrigerator oil recovered by the oil separator to the compressor, for example, sealing failure The possibility of problems such as poor lubrication occurring in the compressor increases.

  Therefore, a pressure sensor for detecting the pressure in the oil return flow path, and first and second pressure loss members respectively provided in portions of the oil return flow path on the oil separator side and the compressor side with respect to the pressure sensor A heat pump is provided that determines that the oil return flow path is normal and that the output increase of the compressor is permitted if the pressure detected by the pressure sensor exceeds the suction pressure of the compressor and is less than the discharge pressure. It is known (see, for example, Patent Document 1). According to this, it is possible to detect the occurrence of an abnormality in the oil return flow path with high accuracy and early.

  However, even if the oil return flow path is in a normal state, refrigeration oil circulating with the refrigerant stays in the piping of the outdoor heat exchanger in an operation or the like where the circulation amount of the refrigerant is low. Insufficient oil may cause problems as described above.

  Therefore, a bypass pipe branched from the pipe between the throttle valve and the distributor and joined to the inlet pipe of the outdoor heat exchanger, a solenoid valve provided for the bypass pipe, a temperature sensor provided for the inlet pipe, compression An air conditioner is known that includes a temperature sensor provided on a suction pipe of the machine and a temperature sensor provided on a discharge pipe of the compressor. The air conditioner opens the solenoid valve when the temperature difference between the inlet pipe and the suction pipe is equal to or greater than the set value, and when the temperature difference is equal to or less than the set value and the temperature of the discharge pipe is equal to or less than the set value. It is comprised so that a solenoid valve may be closed (for example, refer patent document 2).

  According to the above, when the temperature difference between the inlet pipe and the suction pipe is equal to or greater than the set value (for example, 5 ° C.), the (air compressor) of the air conditioner is regarded as overheated and the solenoid valve of the bypass circuit To maintain the circulating amount of the refrigerant and prevent the overheat operation. On the other hand, when the temperature difference is less than the set value and the discharge pipe temperature of the compressor is less than the target value (for example, 60 ° C.), the solenoid valve is closed to prevent a large amount of refrigerant mist from returning to the compressor. be able to.

JP, 2016-173202, A Japanese Patent Application Laid-Open No. 05-302762

  According to the above-described prior art, the occurrence of an abnormality in the oil return passage of the heat pump can be detected with high accuracy and early, or the throttling valve can be bypassed to secure the circulating amount of refrigerant, thereby causing shortage of refrigerator oil in the compressor. Overheating operation resulting from it can be prevented.

  However, in a heat pump provided with a plurality of compressors, for example, deviation of the degree of aged deterioration and / or deviation of operation frequency due to operating conditions may occur between the compressors, installation state of the heat pump (eg, levelness etc.) An imbalance in the supply amount (return amount) of refrigeration oil may occur due to the above. As a result, even when there is a shortage of refrigeration oil in some of the plurality of compressors, problems such as seal failure and lubrication failure occur, and the heat medium is overheated or the compressor is broken. May lead to In the art, no technology has yet been established that can reduce the imbalance in the amount of refrigeration oil supplied among a plurality of compressors constituting such a heat pump.

  As mentioned above, in the said technical field, the technique which can reduce the imbalance of supply_amount | feed_rate of refrigerator oil between several compressors which comprise a heat pump is calculated | required. The present invention has been made to address such a need. That is, according to the present invention, for example, when a shortage of refrigerating machine oil occurs in a part of a plurality of compressors constituting a heat pump used in an air conditioner or the like, the supply amount of the refrigerating machine oil among the plurality of compressors It is an object of the present invention to provide a heat pump control method capable of reducing an imbalance.

  The inventor of the present invention has determined, as a result of intensive research, that in a heat pump provided with a plurality of compressors, a shortage of refrigeration oil has occurred among operating compressors that are operating compressors among the plurality of compressors. By increasing the ratio of the discharge amount of the heat medium from the compressor to the sum of the discharge amounts of the heat medium from these working compressors, it has been found that the shortage of refrigerating machine oil in the compressor can be reduced. .

  In view of the above, the heat pump control method according to the present invention (hereinafter sometimes referred to as the “invention method”) includes a heat medium circulation path and a compression system disposed in the middle of the circulation path The present invention is applied to a heat pump provided with a condenser, an expansion valve and an evaporator, and a control device that controls the operating state of the compressor according to the load. The compression system includes a plurality of compressors arranged in parallel, a suction passage which is a passage through which a heat medium sucked from the circulation passage to the plurality of compressors flows, and a circulation passage through which the heat medium discharged from the plurality of compressors Includes discharge piping, which is a path that flows into.

  The heat pump further includes a temperature sensor that detects a detected discharge temperature, which is a value having a correlation with the temperature of the heat medium discharged from each of the plurality of compressors. And, in a state where there are two or more operating compressors, which are operating compressors among the plurality of compressors, the control device is based on the degree of overheating of the heat medium led based on the discharge temperature of the heat medium A value corresponding to the difference in the degree of overheating of the heat medium between the first compressor, which is the operating compressor with the highest degree of superheat, which is the corresponding value, and the second compressor, the operating compressor with the lowest degree of superheat. It is determined whether or not an imbalanced overheat state, which is a state in which the imbalanced overheat index value is greater than a predetermined threshold, continues for a predetermined period or more. This determination can be performed, for example, based on the first detection temperature which is the detection discharge temperature of the first compressor and the second detection temperature which is the detection discharge temperature of the second compressor. Alternatively, the determination may be a value having a correlation with the first detection pressure, which is a value having a correlation with the pressure of the heat medium discharged from the first compressor, and a value having a correlation with the pressure of the heat medium discharged from the second compressor. It can carry out based on 2 detection pressure and the said 1st detection temperature and 2nd detection temperature. Details of each determination will be described later.

  Then, when it is determined that the above-described imbalanced superheated state continues for a predetermined period or more, the control device occupies a total discharge amount that is the total of the discharge amounts of the heat medium from the plurality of operating compressors. 1 Increase the ratio of the first discharge amount that is the discharge amount of the heat medium from the compressor (hereinafter, the ratio may be simply referred to as the “first ratio”).

  Although the specific method for increasing the ratio (first ratio) of the first discharge amount to the total discharge amount is not particularly limited, for example, at least any one of the processes (1) to (5) listed below By performing one or more, the first percentage can be increased (the details of each process will be described later).

(1) A valve closing process which is a process of decreasing the opening degree of the capacity control valve when the first compressor includes the capacity control valve and the opening degree of the capacity control valve is larger than the minimum opening degree.
(2) When the third compressor, which is an operating compressor other than the first compressor, has a displacement control valve and the opening degree of the displacement control valve is smaller than the maximum opening degree, the opening degree of the displacement control valve is increased Valve opening processing which is processing to
(3) The first compression is configured when the first compressor is configured to be able to change the rotational speed independently of the operating compressors other than the first compressor and the rotational speed of the first compressor is smaller than the maximum speed. Acceleration processing which is processing to increase the rotational speed of the machine.
(4) The third compressor, which is an operating compressor other than the first compressor, is configured to be able to change the rotational speed independently of the other operating compressors, and the rotational speed of the third compressor is less than the minimum speed Processing to reduce the rotational speed of the third compressor or to stop the third compressor if it is too large, or the third compressor so that the rotational speed can be changed independently of the operating compressors other than the third compressor Deceleration processing, which is processing for stopping the third compressor when the third compressor is at the minimum speed and the rotational speed of the third compressor is the minimum speed.
(5) A shutoff process that switches the clutch to the shutoff state when the third compressor, which is an operating compressor other than the first compressor, is driven through the clutch.

  As described above, in the method of the present invention, the detected discharge temperature detected for each of the plurality of compressors provided in the heat pump is acquired. Then, based on the highest degree of superheat (first degree of superheat) and the lowest degree of superheat (second degree of superheat), it is determined whether or not the unequally overheated state continues for a predetermined period or more. Thereby, it is determined whether a shortage of refrigerator oil has occurred in the compressor (first compressor) in which the first degree of superheat has been detected. If it is determined that there is a shortage of refrigeration oil in the first compressor, the controller controls the operating state of the compressor to increase the ratio of the first discharge amount to the total discharge amount (first ratio) Let

  According to the above, the heat medium sucked into the first compressor (and the refrigerant sucked in with the heat medium that accounts for the sum of the flow rates of the heat medium (and the refrigeration oil sucked with the heat medium) in the plurality of working compressors Ratio of the machine oil) increases. As a result, the amount of refrigeration oil drawn into the first compressor also relatively increases. Therefore, according to the method of the present invention, when it is determined that there is a shortage of refrigeration oil in some of the plurality of compressors provided in the heat pump, the amount of refrigeration oil returned to the compressor is increased. It is possible to reduce the imbalance in the supply of refrigeration oil among the plurality of compressors. As a result, it is possible to reduce problems caused by the shortage of refrigeration oil such as sealing failure and lubrication failure.

  Other objects, other features and attendant advantages of the present invention will be readily understood from the description of embodiments of the present invention which will be described with reference to the following drawings.

It is a typical block diagram of the air conditioning apparatus which uses the heat pump to which the control method (1st method) of the heat pump which concerns on 1st Embodiment of this invention is applied. It is a schematic diagram which shows the several compressor used in the heat pump to which a 1st method is applied, and the engine which drives these compressors. It is a flowchart showing the routine which the control apparatus with which the heat pump with which a 1st method is applied is equipped performs. It is a flowchart showing the routine which the control apparatus with which the heat pump provided with the control method (4th method) of heat pump which concerns on 4th Embodiment of this invention is equipped performs. It is a flowchart showing the routine which the control apparatus with which the heat pump with which the control method (the 5th method) of control of heat pump concerning a 5th embodiment of the present invention is provided runs. It is a flowchart showing the routine which the control apparatus with which the heat pump provided with the control method (6th method) of heat pump control which concerns on 6th Embodiment of this invention is equipped performs.

First Embodiment
Hereinafter, a control method of the heat pump according to the first embodiment of the present invention (hereinafter, sometimes referred to as “first method”) will be described.

<Structure of heat pump>
(1) Overall Configuration First, the configuration of an air conditioner using a heat pump to which the first method is applied will be described. FIG. 1: is a schematic diagram which shows an example of a structure of the air conditioning apparatus which uses the heat pump to which a 1st method is applied. The air conditioning apparatus 100 includes an outdoor unit 200 and an indoor unit 300, between which a heat medium is circulated via pipes 330 and 340. The outdoor unit 200 includes a compression system 210 including two compressors 211 and 212 disposed in parallel via a suction header 213 and a discharge header 214, an oil separator 230, a four-way valve 240, a heat exchanger 250 and an electronic expansion. A valve 251 as well as an accumulator 260 are included. That is, the compression system 210 of the heat pump includes two compressors 211 and 212 arranged in parallel, and a suction pipe (a suction pipe (flow) through which a heat medium sucked from the circulation path to the compressor flows. It is configured as a compression system including a header 213) and a discharge pipe (discharge header 214) which is a flow path through which a heat medium discharged from these compressors flows to a circulation path. Although the configuration of the compressors 211 and 212 is not particularly limited, in the present example, both of the two compressors 211 and 212 are scroll compressors.

  Furthermore, buffers 221, strainers 222, 223 and 224, filter drier 225, oil bypass regulator valve 270, high-pressure switch (SW) 281 are provided at predetermined locations of the piping for circulating the heat medium between these components. , And a high pressure sensor 282 are provided. In addition, an outdoor temperature sensor 283 is provided to detect the temperature outside the room.

  On the other hand, the indoor unit 300 includes an electronic expansion valve 310 and a heat exchanger 320. Furthermore, an indoor temperature sensor 284 is provided to detect the temperature of the room to be air conditioned. The heat pump electronic control unit (HP-ECU) 110 is operating, for example, the temperature of the room to be air conditioned detected by the room temperature sensor 284 and the temperature outside the room detected by the outdoor temperature sensor 283. The operation of the compressors 211 and 212 is controlled according to the operating condition and / or environmental conditions of the heat pump, such as the number of indoor units (the number of operating indoor units) and the installation location of the indoor units.

  Further, the outdoor unit 200 includes a path of a heat medium communicating the oil separator 230 with the discharge side (downstream side) and the suction side (upstream side) of the accumulator 260, and a hot gas bypass valve 290 for blocking and opening the path. ,including. When the path is opened by the hot gas bypass valve 290, the heat medium discharged from the compressors 211 and 212 bypass the heat exchanger 250 and returns to the compressors 211 and 212 via the accumulator 260. .

  In addition, the compressors 211 and 212 are located from the downstream area, which is a partial area of the compression path that is a path through which the heat medium flows inside the compressor, to the partial area of the compression path and upstream from the downstream area. A bypass path as a path for returning the heat medium to an upstream area which is a partial area or a partial area of the inner area of the suction pipe located upstream of the compression path, and bypass paths 291p and 292p, and a capacity interposed in the bypass path Control valves 291 and 292 are provided, respectively. By increasing the opening degree of the capacity control valves 291 and 292, the amount of work on the downstream side in the compression path of the compressors 211 and 212 is significantly reduced and the work rate of the compressors 211 and 212 is reduced. It can be done.

  The flow direction of the heat medium in the air conditioning apparatus 100 is indicated by the solid arrows (during cooling) and broken arrows (during heating) shown in the figure, the operation mode (cooling mode and air conditioning of the air conditioning apparatus 100). It depends on the heating mode). Thus, at the time of cooling, the heat exchanger 250 of the outdoor unit 200 functions as a condenser, and the heat exchanger 320 of the indoor unit 300 functions as an evaporator. On the other hand, at the time of heating, the heat exchanger 250 of the outdoor unit 200 functions as an evaporator, and the heat exchanger 320 of the indoor unit 300 functions as a condenser. However, the circulation path (discharge side path) from the compressors 211 and 212 to the four-way valve 240 via the oil separator 230 and the circulation path from the four-way valve 240 to the compressors 211 and 212 via the accumulator 260 and the strainer 224 In the side path, as indicated by the arrows in the figure, the flow direction of the heat medium is always the same regardless of the operation mode.

  The configurations of the heat pump and the air conditioner described above are merely examples, and the configurations of the heat pump to which the first method is applied and the air conditioner using the heat pump are not limited to the above. For example, the compressor is not limited to a scroll compressor, and may be a compressor according to another scheme. Further, the number of compressors provided in the heat pump is not limited to two, and may be three or more. Furthermore, although the compressors 211 and 212 mentioned above are equipped with the solenoid valve 291 and 292 respectively, the compressor which comprises the heat pump to which a 1st method is applied does not necessarily need to be equipped with a capacity control valve.

(2) Drive mechanism of compressor by engine Referring to FIG. 1, an engine 400 as a drive source for driving the compressors 211 and 212 and an engine electronic control unit (ENG-ECU) 410 for controlling the operation of the engine 400. Is omitted. Thus, these details will be described below with reference to FIG.

  As described above, the heat pump electronic control unit (HP-ECU) 110 is, for example, the indoor temperature to be subjected to air conditioning detected by the indoor temperature sensor 284, the outdoor temperature detected by the outdoor temperature sensor 283, and operation The operation of the compressors 211 and 212 is controlled in accordance with the operating condition and / or environmental conditions of the heat pump, such as the number of indoor units (the number of operating indoor units) and the installation location of the indoor units.

  The compressors 211 and 212 are belt driven by the engine 400. In this example, as shown in FIG. 2, the drive mechanism is configured such that one belt drives both of the two compressors 211 and 212 by the engine 400. Further, the two compressors 211 and 212 each have a clutch (not shown). In each of the compressors, a transmission state in which the driving force is transmitted from the engine 400 to the compressor and a blocking state in which the driving force is not transmitted from the engine 400 to the compressor by these clutches. It can be switched independently.

  The drive mechanism can switch between operating both the compressors 211 and 212 or operating only one of the compressors 211 and 212 depending on the operating condition of the heat pump and / or the environmental conditions. Also, as a matter of course, by stopping the engine 400, both of the compressors 211 and 212 can be stopped, and the compression system 210 in the heat pump can be stopped.

  However, the drive mechanism may be configured such that each of the two compressors 211 and 212 is individually belt driven by the engine 400. Further, the drive mechanism may be configured such that only some of the plurality of compressors include the clutch.

  The engine electronic control unit (ENG-ECU) 410 controls the operating conditions (for example, the rotational speed, etc.) and the number of operating compressors 211 and 212 determined according to the operating conditions and / or environmental conditions of the heat pump as described above. For example, the rotational speed and torque of the engine 400 are controlled.

  That is, the heat pump electronic control unit (HP-ECU) 110 and the engine electronic control unit (ENG-ECU) 410 constitute a control unit provided in the heat pump to which the method of the present invention is applied. However, the configuration of the control device is not particularly limited, and may be divided into a plurality of ECUs as shown in the present example, or one ECU may be configured to achieve all the functions.

  In the above, the embodiment in which the two compressors 211 and 212 each having a clutch is belt-driven by the engine 400 has been exemplified. However, the drive source of the compressor constituting the heat pump to which the first method is applied is not limited to the engine, and other power sources such as a motor can be used. In addition, as described above, all of the plurality of compressors constituting the heat pump may be driven by one drive source, or the individual compressors may be driven by respective drive sources (for example, motors). .

<Control of heat pump>
As described above, the heat pump to which the first method is applied includes the heat medium circulation path (including the pipes 330 and 340) and the compression system (210) disposed in the middle of the circulation path, the condenser and the evaporator. (250 and 320), an expansion valve (251), and a controller (HP-ECU 110 and / or ENG-ECU 410) for controlling the operating state of the compressor (211 and 212) according to the load. Furthermore, the compression system (210) includes a plurality of compressors arranged in parallel, a path through which a heat medium to be sucked from the circulation path to the plurality of compressors flows (including the suction header 213), and a plurality And a discharge pipe (including the discharge header 214), which is a path through which the heat medium discharged from the compressor flows to the circulation path.

  In addition to the above, the heat pump to which the first method is applied is a temperature sensor (501 and 502) for detecting the detected discharge temperature, which is a value having a correlation with the temperature of the heat medium discharged from each of the plurality of compressors. Further comprising The detected discharge temperature detected by these temperature sensors may not necessarily be the temperature of the heat medium discharged from the compressor itself, as long as it has a value correlated with the temperature of the heat medium discharged from the compressor, It may be any value. As the detected discharge temperature, for example, the temperatures of the compression mechanism of the individual compressors, the discharge port, the discharge pipe, and the like can be adopted, and the temperature sensor can be disposed accordingly.

  In addition, in the state where there are two or more operating compressors, which are operating compressors among the plurality of compressors, the control device determines whether or not the imbalanced superheated state continues for a predetermined period or more. Determine if The imbalanced overheat condition is a condition in which the imbalanced overheat index value is greater than a predetermined threshold. The imbalanced overheat index value is a value corresponding to the difference in the degree of overheating of the heat medium between the first compressor and the second compressor. The first compressor is a compressor with the highest degree of superheat among the operating compressors, and the second compressor is a compressor with the lowest superheat among the operating compressors.

  The degree of superheat is a value corresponding to the degree of overheating of the heat medium, and is derived based on the detected discharge temperature. For example, the detected discharge temperature in each compressor may be adopted as the degree of superheat. Alternatively, the degree of superheat may be derived based not only on the detected discharge temperature but also on other state quantities (for example, the pressure of the heat medium discharged from the compressor). In this case, for example, the discharge superheat degree in each compressor may be adopted as the superheat degree. An embodiment adopting such a degree of superheat will be described in detail later.

  The imbalance overheating index value is a value corresponding to the difference in the degree of overheating of the heat medium between the first compressor and the second compressor as described above. Specifically, for example, the imbalanced overheat index value can be specified based on the first degree of superheat in the first compressor and the second degree of superheat in the second compressor. . More specifically, for example, the difference between the first degree of superheat and the second degree of superheat can be adopted as the imbalance overheat indicator value.

  The above-mentioned “predetermined threshold” is, for example, an upper limit value of an allowable range of the difference between the degree of overheating of the heat medium in the first compressor and the degree of overheating of the heat medium in the second compressor It can be defined as an overheat indicator value. A specific value of this threshold is, for example, in a model further incorporating a sensor capable of detecting a state quantity (eg, temperature and pressure of the heat medium, etc.) corresponding to the degree of overheating of the heat medium in each compressor. It can be determined by a preliminary experiment or the like which compares the degree of overheating of the heat medium in each compressor, which is derived based on the amount of state detected by these sensors, with the imbalance heating value. In addition, the said threshold value may be called "the threshold value for determination" in the following description.

  In the “predetermined period”, the imbalanced overheat state in which the imbalanced overheat index value is larger than the predetermined threshold (determination threshold) continues due to a sudden factor such as noise in the detection signal of the temperature sensor, for example. It can be defined as a temporal length low enough. The specific length of this period is determined, for example, by a preliminary experiment or the like which measures temporal fluctuation of the imbalanced overheat index value in the compressor constituting the heat pump having the same configuration as the heat pump to which the first method is applied. be able to. In addition, the said period may be called "period for determination" in the following description.

  If it is determined that the unbalanced overheating state continues for a predetermined period (period for determination) or more, the probability that the first compressor suffers from a shortage of refrigeration oil is high. Therefore, the control device controls the operation of the first compressor 211 and the second compressor 212 such that the supply amount (return amount) of the refrigerator oil to the first compressor is increased.

  Specifically, the control device controls the ratio of the first discharge amount that is the discharge amount of the heat medium from the first compressor to the total discharge amount that is the sum of the discharge amounts of the heat medium from the plurality of operating compressors Increase the first rate). On the other hand, as described above, the heat pump electronic control unit (HP-ECU) 110 is, for example, the indoor temperature to be air conditioned detected by the indoor temperature sensor 284 and the outdoor temperature detected by the outdoor temperature sensor 283. The operation of the compressors 211 and 212 is controlled in accordance with the operating condition of the heat pump and / or the environmental conditions, such as the number of operating indoor units (the number of operating indoor units) and the installation location of the indoor units. That is, the control device controls the rotational speeds and the like of the compressors 211 and 212 so as to achieve the total discharge amount of the heat medium according to the load of the heat pump. Therefore, the control device can increase the first discharge amount by increasing the first ratio as described above, and as a result, can increase the supply amount (return amount) of the refrigerator oil to the first compressor. .

  As a result, the shortage of refrigeration oil in the first compressor is alleviated, and problems such as seal failure and lubrication failure occur in the first compressor, for example, and the heat medium is repeatedly compressed and overheated or the first compressor is damaged. The risk of causing problems is reduced.

  The specific method for increasing the first ratio is not particularly limited, and for example, as described above, at least any one or two of the processes (1) to (5) listed below. By performing the above, the first ratio can be increased (the details of each process will be described later).

(1) A valve closing process which is a process of decreasing the opening degree of the capacity control valve when the first compressor includes the capacity control valve and the opening degree of the capacity control valve is larger than the minimum opening degree.
(2) When the third compressor, which is an operating compressor other than the first compressor, has a displacement control valve and the opening degree of the displacement control valve is smaller than the maximum opening degree, the opening degree of the displacement control valve is increased Valve opening processing which is processing to
(3) The first compression is configured when the first compressor is configured to be able to change the rotational speed independently of the operating compressors other than the first compressor and the rotational speed of the first compressor is smaller than the maximum speed. Acceleration processing which is processing to increase the rotational speed of the machine.
(4) The third compressor, which is an operating compressor other than the first compressor, is configured to be able to change the rotational speed independently of the operating compressor other than the third compressor, and the rotational speed of the third compressor To reduce the rotational speed of the third compressor if the speed is greater than the minimum speed or to stop the third compressor, or to change the rotational speed independently of the operating compressor other than the third compressor A deceleration process which is a process of stopping the third compressor when the third compressor is configured and the rotational speed of the third compressor is the minimum speed.
(5) A shutoff process that switches the clutch to the shutoff state when the third compressor, which is an operating compressor other than the first compressor, is driven through the clutch.

<Flow of specific processing>
The ECUs (HP-ECU 110 and / or ENG-ECU 410) constituting the control device provided in the heat pump to which the first method is applied execute, for example, the algorithm represented by the routine shown in the flowchart of FIG. 1 Implement the method. The said routine is performed by a predetermined | prescribed short cycle, when CPU which comprises said ECU performs various arithmetic processing according to the program stored in ROM which comprises said ECU.

  When the routine is started, in step S31, it is determined whether or not two or more operating compressors, which are operating compressors, exist among the plurality of compressors. If the number of operating compressors is less than 2 (i.e., 1 or 0 (zero)), the CPU determines that the result is "No", and once ends the routine. On the other hand, when the number of operating compressors is two or more, the CPU makes a “Yes” determination, and proceeds to the next step S32, and the temperature sensor (501 and 502) corresponding to each of the plurality of operating compressors (211 and 212). The detected discharge temperature (Td) of each compressor is acquired from. Next, the CPU proceeds to step S33 to respond to the degree of overheating of the heat medium in each of the operating compressors based on the plurality of detected discharge temperatures (Td) corresponding to the acquired plurality of operating compressors. Calculate the degree of superheat, which is a value.

  Next, the CPU proceeds to step S34, and based on the first degree of superheat (Hd1), which is the highest degree of superheat among the calculated degrees of superheat, and the second degree of superheat (Hd2), which is the lowest degree of superheat, An imbalance overheat index value (ΔHd), which is a value corresponding to the difference in degree, is calculated. In this example, as described above, the difference between the first degree of superheat (Hd1) and the second degree of superheat (Hd2) is adopted as the imbalance overheat index value (ΔHd) (ΔHd = Hd1−Hd2). Next, the CPU proceeds to step S35, and determines whether the calculated imbalance overheat index value (ΔHd) is larger than the above-described predetermined determination threshold (Hdth).

  If the imbalanced overheat index value (ΔHd) is less than or equal to the determination threshold (Hdth), the CPU determines “No” in step S35, and the routine is temporarily ended.

  On the other hand, when the imbalanced overheat index value (ΔHd) is larger than the determination threshold (Hdth), the CPU determines “Yes” in step S35, and proceeds to the next step S36. In step S36, the CPU determines whether a state where the imbalance overheating index value (ΔHd) is larger than the judgment threshold (Hdth) (imbalance overheating state) continued over the judgment period (Pj) or more. Determine

  If the imbalanced overheat state has not continued for the determination period (Pj) or more, the CPU determines “No” in step S33, returns to step S31 described above, and repeatedly executes the routine.

  On the other hand, if the imbalanced overheat state continues over the determination period (Pj) or more, the CPU determines “Yes” in step S36, and proceeds to the next step S37. In step S37, the CPU corresponds to the first detected temperature (Td1) in the total discharge amount which is the sum of the discharge amounts of the heat medium from the plurality of operating compressors (211 and 212) included in the compression system. The ratio (first ratio) of the first discharge amount, which is the discharge amount of the heat medium from the (first compressor), is increased.

  According to the above, the supply amount (return amount) of the refrigerator oil to the first compressor can be increased, and the shortage of the refrigerator oil in the first compressor can be reduced. As a result, it is possible to reduce the possibility that problems such as sealing failure and lubrication failure may occur in the first compressor to cause overheating of the heat medium or damage to the first compressor.

Second Embodiment
Hereinafter, a method of controlling a heat pump according to the second embodiment of the present invention (hereinafter, may be referred to as “second method”) will be described.

<Composition and control of heat pump>
The configuration of the heat pump to which the second method is applied is similar to the configuration of the heat pump to which the first method described above with reference to FIGS. 1 and 2 is applied, and therefore the description will not be repeated here. In addition, since the control of the heat pump in the second method and the flow of specific processing included in the control are also similar to the first method described above with reference to FIG. 3, the description will not be repeated here.

  However, in the second method, the control device uses the detected discharge temperature as the degree of superheat. As described above, the detected discharge temperature is a value having a correlation with the temperature of the heat medium discharged from each of the compressors. Therefore, since a proper amount of refrigeration oil is not supplied to the compressor, for example, problems such as seal failure and lubrication failure occur in the compressor, and when the heat medium is repeatedly compressed and overheated, the detected discharge temperature rises Do. That is, the detected discharge temperature is one of the values corresponding to the degree of overheating of the heat medium, and can be used as the degree of superheat. In addition, the detected discharge temperature can be easily detected by the temperature sensor.

  Furthermore, in the second method, the controller unbalances the difference between the first degree of superheat (which is the degree of superheat in the first compressor) and the second degree of superheat (which is the degree of superheat in the second compressor) Calculated as an index value. That is, in the second method, the detected discharge temperature of the first compressor, which is the compressor with the highest detected discharge temperature, and the detected discharge of the second compressor, which is the compressor with the lowest detected discharge temperature. The result of simple subtraction from the second detected temperature, which is the temperature, can be calculated as the imbalance overheating index value.

  As described above, in the second method, by using the detected discharge temperature as the degree of superheat, the control method of the heat pump according to the present invention can be simply and simply without applying an excessive calculation load to the CPU configuring the control device The method of the invention can be carried out. Thereby, the shortage of the refrigerator oil in the first compressor is alleviated by simpler processing, and problems such as seal failure and lubrication failure occur in the first compressor, for example, and the heat medium exceeds the allowable temperature of the parts. It is possible to reduce the possibility of overheating leading to a problem of breakage of the first compressor.

Third Embodiment
Hereinafter, a method of controlling a heat pump (hereinafter, may be referred to as “third method”) according to the third embodiment of the present invention will be described.

<Composition and control of heat pump>
The configuration of the heat pump to which the third method is applied is also basically the same as the configuration of the heat pump to which the first method and the second method described above are applied, so the description will not be repeated here. However, as described below, in the third method, the degree of superheat which is a value corresponding to the degree of overheating of the heat medium in each compressor is not only the discharge temperature of the heat medium detected by the temperature sensor It is led based on the discharge pressure of the heat carrier detected by the pressure sensor. Except for this point, the control of the heat pump in the third method and the specific process flow included in the control are also the same as the first method and the second method described above with reference to FIG. Do not repeat

  As described above, in the third method, the degree of superheat which is a value corresponding to the degree of overheating of the heat medium in each compressor is detected not only by the discharge temperature of the heat medium detected by the temperature sensor but also by the pressure sensor It is led based on the discharge pressure of the heat medium which is carried out. Therefore, the heat pump to which the third method is applied further includes a pressure sensor that detects a detected discharge pressure that is a value having a correlation with the pressure of the heat medium discharged from each of the plurality of compressors. The detected discharge pressure detected by these pressure sensors may not necessarily be the pressure of the heat medium discharged from the compressor itself, as long as it has a value correlated with the pressure of the heat medium discharged from the compressor, It may be any value. As the detection discharge pressure, for example, the pressure of the heat medium in the compression mechanism, discharge port, discharge pipe, etc. of each compressor can be adopted, and a pressure sensor can be disposed accordingly.

  Furthermore, in the third method, the control device uses, as the degree of superheat, the discharge superheat degree obtained by subtracting the saturated vapor temperature of the heat medium at the detection discharge pressure from the detected discharge temperature. As well known to those skilled in the art, the degree of discharge superheat is the difference between the saturated vapor temperature (condensing temperature) at the discharge pressure of the heat medium discharged from the compressor and the discharge temperature of the heat medium, and saturation from the discharge temperature It can be calculated by subtracting the steam temperature. The degree of discharge superheat is a value having a correlation with the degree of shortage of the amount of heat medium, and the higher the degree of discharge superheat, the higher the degree of shortage of the amount of heat medium, and as a result, the degree of overheating of the heat medium.

  As described above, the discharge superheat degree is one of the values corresponding to the degree of superheat of the heat medium, and can be used as the above-described superheat degree. When the amount of heat transfer medium is insufficient, the amount of refrigeration oil returned to the compressor along with the heat transfer medium is also insufficient. Therefore, it can be said that the discharge superheat degree is a value having a correlation with the degree of shortage of the amount of refrigeration oil. That is, it can be said that the degree of discharge superheat is a more accurate index of the amount of refrigerating machine oil in consideration of the discharge pressure of the heat medium discharged from each compressor.

  In addition, in the third method, the controller unbalances the difference between the first degree of superheat (which is the degree of superheat in the first compressor) and the second degree of superheat (which is the degree of superheat in the second compressor) Calculated as the overheat index value. That is, in the third method, a simple subtraction of the discharge superheat degree of the first compressor, which is the compressor with the highest discharge superheat degree, and the discharge superheat degree of the second compressor, which is the compressor with the lowest discharge superheat degree. Can be calculated as the imbalanced overheat index value.

  As described above, in the third method, by using the discharge superheat degree as the superheat degree, the control method of the heat pump according to the present invention corresponds to the amount of the refrigerator oil in each compressor more accurately. Method) can be implemented. As a result, the shortage of refrigerating machine oil in the first compressor is alleviated, and problems such as sealing failure and lubrication failure occur in the first compressor, for example, and the heat medium overheats beyond the allowable temperature of the component to cause the first compression. It is possible to more accurately reduce the possibility of the problem of the machine being damaged.

Fourth Embodiment
Hereinafter, a control method of the heat pump (hereinafter, may be referred to as “fourth method”) according to the fourth embodiment of the present invention will be described.

<Structure of heat pump>
The configuration of the heat pump to which the second method is applied is basically the same as the configuration of the heat pump to which the first to third methods described above are applied, so the description will not be repeated here. However, as described below, in the fourth method, the discharge amount ratio is increased using the bypass path and the displacement control valve described above. Therefore, at least a part of the plurality of compressors constituting the heat pump to which the fourth method is applied needs to be provided with the bypass path and the capacity control valve described above. In the present embodiment, as described with reference to FIG. 1, both of the plurality of compressors 211 and 212 have bypass paths 291 p and 292 p and capacity control valves 291 and 292.

<Control of heat pump>
Also in the fourth method, similarly to the first method to the third method, it is determined that the imbalanced overheat state in which the imbalanced overheat index value is larger than the predetermined threshold continued for a predetermined period or more. At the same time, the control device increases the ratio (first ratio) of the first discharge amount to the total discharge amount. However, in the fourth method, one or both of the valve closing process and the valve opening process described in the following (1) and (2) among the processes (1) to (5) described above are It is executed by the controller.

  (1) Valve closing processing ... from the first downstream area which is a partial area of the first path which is a path through which the heat medium flows inside the first compressor to the partial area of the first path which is upstream of the first downstream area The first bypass path, which is a path for returning the heat medium to the first upstream area, which is a partial area of the inner area of the suction piping located upstream of the partial area located on the side or the first path The first compressor is provided with a first valve, which is a displacement control valve interposed between the first and second valves, and the opening degree of the first valve is decreased when the opening degree of the first valve is larger than the minimum opening degree.

  (2) Valve opening processing ... A third downstream region which is a partial region of a third path in which a heat medium flows inside the third compressor, which is an operating compressor other than the first compressor. To a third upstream region which is a partial region of the third path and located upstream of the third downstream region or a partial region of the inner region of the suction pipe located upstream of the third route In the case where the third bypass path, which is a path for returning the heat medium, and the third valve, which is a displacement control valve interposed in the third bypass path, are provided and the opening degree of the third valve is smaller than the maximum opening degree Increase the opening degree of the third valve.

  The "maximum opening degree" and the "minimum opening degree" of the valve opening degree of the displacement control valve correspond to the upper limit and the lower limit of the range of the valve opening degree of the displacement control valve in a normal state. In general, the maximum opening, which is the upper limit, corresponds to the valve opening of the displacement control valve in the fully open state, and the minimum opening, which is the lower limit, is the valve opening of the displacement control valve in the fully closed state. It corresponds.

  The first path and the third path, the first downstream area and the third downstream area, and the first upstream area and the third upstream area in the above description are the compression paths described in the description of the air conditioner 100 shown in FIG. It corresponds to the downstream area and the upstream area, respectively. Furthermore, the first and third valves in the above description correspond to the displacement control valves 291 and 292 described in the description of the air conditioner 100 shown in FIG.

  When the valve closing process shown in the above (1) is executed, the capacity control valve of the first compressor, which is an operating compressor having the highest degree of superheat (which is a value corresponding to the degree of overheating of the heat medium) is opened. As the degree is reduced (or closed), the power of the first compressor can be increased to increase the amount of heat transfer medium introduced into the first compressor. As a result, since the supply amount (return amount) of refrigeration oil to the first compressor increases, the shortage of refrigeration oil in the first compressor can be reduced, and problems such as sealing failure and lubrication failure can be reduced. .

  On the other hand, when the valve opening process shown in the above (2) is executed, the opening degree of the capacity control valve of the third compressor which is an operating compressor other than the first compressor which is the operating compressor having the highest degree of superheat. As the pressure control valve is increased (or the capacity control valve is opened from the fully closed state), the work rate of the third compressor can be decreased to reduce the suction amount of the heat medium to the third compressor. Along with this, the amount of suction of the heat medium to the first compressor increases. As a result, since the supply amount (return amount) of refrigeration oil to the first compressor increases, the shortage of refrigeration oil in the first compressor can be reduced, and problems such as sealing failure and lubrication failure can be reduced. .

  Note that the displacement control valve provided in the first compressor and / or the third compressor may be a valve that can change the opening degree (valve opening degree) continuously or stepwise as described above, Alternatively, it may be an open / close valve that switches between a fully open state and a fully closed state as in a so-called "capacity solenoid valve". Also, in any case, the displacement control valve may be any type of normally-open or normally-close type valve.

  Furthermore, the third compressor is not particularly limited as long as it is an operating compressor other than the first compressor. However, regardless of whether the valve closing process or the valve opening process is performed, the suction amount of the heat medium to the third compressor decreases as the suction amount of the heat medium to the first compressor increases. In particular, in the valve opening process, the amount of suction of the heat medium to the third compressor is positively reduced. Therefore, from the viewpoint of reducing the possibility of causing shortage of refrigeration oil in the third compressor by executing the valve opening process, the second compressor, which is the operating compressor with the lowest degree of superheat, is adopted as the third compressor Is preferred.

<Flow of specific processing>
The ECU (HP-ECU 110 and / or ENG-ECU 410) constituting the control device included in the heat pump to which the fourth method is applied executes, for example, the algorithm represented by the routine shown in the flowchart of FIG. 4 Implement the method. The said routine is performed by a predetermined | prescribed short cycle, when CPU which comprises said ECU performs various arithmetic processing according to the program stored in ROM which comprises said ECU.

  The flowchart of FIG. 4 is the same as the flowchart of FIG. 3 except that the discharge amount ratio of the first compressor is increased by executing the valve closing process and / or the valve opening process in step S37. Therefore, the description of the process from step S31 to step S35 is omitted.

  The imbalanced overheat index value (ΔHd) calculated based on the first degree of superheat (Hd1) which is the highest degree of superheat and the second degree of superheat (Hd2) which is the lowest degree of heat is higher than the determination threshold (Hdth) If the large state (imbalanced overheated state) does not continue over the determination period (Pj) or more, the CPU determines "No" in step S36, returns to step S31 described above, and the routine Execute repeatedly.

  On the other hand, if the imbalanced overheat state continues over the determination period (Pj) or more, the CPU determines "Yes" in step S36, and proceeds to the next step S37. In step S37, the CPU corresponds to the first superheat degree (Hd1) in the total discharge amount which is the sum of the discharge amounts of the heat medium from the plurality of operating compressors (211 and 212) included in the compression system. The ratio (first ratio) of the first discharge amount, which is the discharge amount of the heat medium from the (first compressor), is increased.

  At this time, in the fourth method, as shown in step S37 in the flowchart of FIG. 4, the first discharge accounts for the total discharge amount by executing either or both of the valve closing process and the valve opening process described above. Increase the proportion of the amount (the first proportion).

  According to the above, the supply amount (return amount) of the refrigerator oil to the first compressor can be increased, and the shortage of the refrigerator oil in the first compressor can be reduced. As a result, for example, problems such as seal failure and lubrication failure occur in the first compressor, and the possibility that the heat medium may overheat to exceed the allowable temperature of the parts and the first compressor may be damaged is reduced. Ru.

Fifth Embodiment
Hereinafter, a control method of the heat pump (hereinafter, may be referred to as a “fifth method”) according to the fifth embodiment of the present invention will be described.

<Structure of heat pump>
The configuration of the heat pump to which the fifth method is applied is basically the same as the configuration of the heat pump to which the first to fourth methods described above are applied, so the description will not be repeated here. However, as described below, in the fifth method, the discharge amount ratio is increased by individually increasing the rotational speed of the first compressor or individually reducing the rotational speed of the third compressor. . Therefore, at least a part of the plurality of compressors constituting the heat pump to which the fifth method is applied needs to be configured to be able to change the rotational speed individually.

  As a specific example of the above configuration, for example, a configuration in which each of the plurality of compressors is provided with a dedicated drive source and / or a transmission mechanism can be mentioned. In this example, each of the plurality of compressors 211 and 212 is provided with a motor and a power supply device as a dedicated drive source (both are not shown).

<Control of heat pump>
Also in the fifth method, similarly to the first to fourth methods, it is determined that the imbalanced overheat state in which the imbalanced overheat index value is larger than the predetermined threshold continued for a predetermined period or more. At the same time, the control device increases the ratio (first ratio) of the first discharge amount to the total discharge amount. However, in the fifth method, one or both of the acceleration processing and the deceleration processing described in (3) and (4) below among the above-described processing (1) to (5) are control devices. Performed by

(3) Acceleration processing: when the first compressor is configured to be able to change the rotational speed independently of the operating compressors other than the first compressor and the rotational speed of the first compressor is smaller than the maximum speed The rotational speed of the first compressor is increased.
(4) Deceleration processing ... The third compressor, which is an operating compressor other than the first compressor, is configured to be able to change the rotational speed independently of the operating compressor other than the third compressor, and the third compressor The rotational speed of the third compressor is reduced or the third compressor is stopped when the rotational speed of the motor is greater than the minimum speed. Alternatively, when the third compressor is configured to be able to change the rotational speed independently of the operating compressors other than the third compressor and the rotational speed of the third compressor is the minimum speed, the third compressor may be used. Stop it. Thus, the deceleration processing also includes stopping the third compressor.

  As described above, in the present embodiment, each of the plurality of compressors 211 and 212 includes the motor and the power supply as a dedicated drive source. Therefore, even if there is a shortage of refrigeration oil in any of the compressors, one compressor can change its rotational speed independently of the other compressor. In this case, the rotational speed of each compressor controls the rotational speed of the motor by controlling the electric power (for example, frequency and voltage etc.) supplied from the power supply to the motor as the drive source, thereby the compressor Control the rotational speed of the The specific method for controlling the rotational speed of the motor by the supplied power may be selected from various methods known to those skilled in the art, for example, according to the type of motor (for example, AC type or DC type). And can be selected as appropriate.

  Also, the terms "maximum speed" and "minimum speed" for the rotational speed of the compressor refer to the rotational speed of the compressor that can be driven in a stable state by the drive source (in this example, the motor) Correspond to the upper and lower limits of the range of For example, if it is attempted to operate the compressor at a rotational speed exceeding the maximum speed which is the upper limit, there is a risk that the operating state of the drive source such as a motor and an engine may become unstable. Conversely, when trying to operate the compressor at a rotational speed below the lower limit which is the lower limit, for example, the operating state of the drive source such as the motor and engine becomes unstable or an engine stall (stop of the engine) occurs. There is a risk of

  When the acceleration process shown in the above (3) is executed, the rotational speed of the first compressor, which is the operating compressor having the highest degree of superheat (which is a value corresponding to the degree of overheating of the heat medium), is increased. And the suction amount of the heat medium to the first compressor can be increased. As a result, since the supply amount (return amount) of refrigeration oil to the first compressor increases, the shortage of refrigeration oil in the first compressor can be reduced, and problems such as sealing failure and lubrication failure can be reduced. .

  On the other hand, when the speed reduction process shown in the above (4) is executed, the rotational speed of the third compressor, which is an operating compressor other than the first compressor, which is the operating compressor having the highest degree of superheat, decreases. The suction amount of the heat medium to the third compressor can be reduced. Along with this, the amount of suction of the heat medium to the first compressor increases. As a result, since the supply amount (return amount) of refrigeration oil to the first compressor increases, the shortage of refrigeration oil in the first compressor can be reduced, and problems such as sealing failure and lubrication failure can be reduced. .

  The third compressor is not particularly limited as long as it is an operating compressor other than the first compressor. However, regardless of whether the acceleration process or the deceleration process is performed, the suction amount of the heat medium to the third compressor decreases as the suction amount of the heat medium to the first compressor increases. In particular, in the deceleration processing, the amount of suction of the heat medium to the third compressor is positively reduced. Therefore, from the viewpoint of suppressing the possibility of causing shortage of refrigeration oil in the third compressor by executing the deceleration processing, adopting the second compressor, which is the operating compressor with the lowest degree of superheat, as the third compressor Is preferred.

<Flow of specific processing>
The ECU (the HP-ECU 110 and / or the motor control ECU not shown) constituting the control device of the heat pump to which the fifth method is applied executes, for example, the algorithm represented by the routine shown in the flowchart of FIG. Implement the fifth method. The said routine is performed by a predetermined | prescribed short cycle, when CPU which comprises said ECU performs various arithmetic processing according to the program stored in ROM which comprises said ECU.

  The flowchart of FIG. 5 is the same as the flowcharts of FIGS. 3 and 4 except that the discharge amount ratio of the first compressor is increased by execution of acceleration processing and / or deceleration processing in step S37. Therefore, the description of the process from step S31 to step S35 is omitted.

  The imbalanced overheat index value (ΔHd) calculated based on the first degree of superheat (Hd1) which is the highest degree of superheat and the second degree of superheat (Hd2) which is the lowest degree of heat is higher than the determination threshold (Hdth) If the large state (imbalanced overheated state) does not continue over the determination period (Pj) or more, the CPU determines "No" in step S36, returns to step S31 described above, and the routine Execute repeatedly.

  On the other hand, if the imbalanced overheat state continues over the determination period (Pj) or more, the CPU determines "Yes" in step S36, and proceeds to the next step S37. In step S37, the CPU corresponds to the first superheat degree (Hd1) in the total discharge amount which is the sum of the discharge amounts of the heat medium from the plurality of operating compressors (211 and 212) included in the compression system. The ratio (first ratio) of the first discharge amount, which is the discharge amount of the heat medium from the (first compressor), is increased.

  At this time, in the fifth method, as shown in step S37 in the flowchart of FIG. 5, the first ratio is increased by executing one or both of the acceleration processing and the deceleration processing described above.

  According to the above, the supply amount (return amount) of the refrigerator oil to the first compressor can be increased, and the shortage of the refrigerator oil in the first compressor can be reduced. As a result, it is possible to reduce the possibility that problems such as sealing failure and lubrication failure may occur in the first compressor to cause overheating of the heat medium or damage to the first compressor.

  In the above, the case has been described in which each of the plurality of compressors 211 and 212 includes the motor and the power supply device as a dedicated drive source and the motor control ECU. However, the fifth method can be applied to any heat pump as long as it is possible to individually increase the rotational speed of the first compressor or to individually decrease the rotational speed of the third compressor. That is, at least a part of the plurality of compressors constituting the heat pump to which the fifth method is applied may be configured to be able to change the rotational speed individually, and the drive source of the compressor is limited to the motor For example, it may be another drive source such as an engine.

Sixth Embodiment
Hereinafter, a control method of the heat pump (hereinafter, may be referred to as a “sixth method”) according to the sixth embodiment of the present invention will be described.

<Structure of heat pump>
The configuration of the heat pump to which the sixth method is applied is basically the same as the configuration of the heat pump to which the first to fifth methods described above are applied, so the description will not be repeated here. However, as described below, in the sixth method, the discharge amount ratio is increased by interrupting the driving force to the third compressor. Therefore, at least a part of the plurality of compressors constituting the heat pump to which the sixth method is applied needs to be equipped with a mechanism for switching between transmission and shutoff of the driving force from the driving source.

  As a specific example of the above mechanism, for example, as described with reference to FIG. 2, a clutch can be mentioned. According to the clutch, in each of the compressor, a transmission state in which the driving force is transmitted from the engine 400 to the compressor and a blocking state in which the driving force is not transmitted from the engine 400 to the compressor. It can be switched independently. In this example, each of the plurality of compressors 211 and 212 includes a clutch (not shown).

<Control of heat pump>
Also in the sixth method, as in the first to fifth methods, it is determined that the imbalanced overheat state in which the imbalanced overheat index value is larger than the predetermined threshold continued for a predetermined period or more. At the same time, the control device increases the ratio (first ratio) of the first discharge amount to the total discharge amount. However, in the fourth method, among the above-described processes (1) to (5), the shutoff process described in (5) below is executed by the control device.

  (5) Shut-off process ... Transmission state in which the driving force from the drive source is transmitted to the third compressor in the third compressor, which is an operating compressor other than the first compressor, and the driving force from the drive source Is provided with a third clutch that is a mechanism for switching the drive state of the third compressor between the shutoff state where the power transmission is not transmitted to the third compressor, and the third compressor using the third clutch Switch the drive state of the to the blocking state.

  As described above, in the present example, each of the plurality of compressors 211 and 212 includes a clutch. Therefore, in any of the compressors, it is possible to switch between the transmission state in which the driving force from the driving source is transmitted and the blocking state in which the driving force from the driving source is not transmitted.

  However, the first compressor, which is an operating compressor with the highest degree of superheat (which is a value corresponding to the degree of overheating of the heat medium), is operating. That is, the drive state of the first compressor is in the transmission state, and even if it is switched to the shut-off state, the supply amount (return amount) of the refrigeration oil to the first compressor can not be increased. Therefore, in the sixth method, as described above, when the third compressor, which is an operating compressor other than the first compressor, includes a clutch and the drive state of the third compressor is in the transmission state, Is switched to the blocking state (the blocking process shown in the above (5) is executed).

  When the shutoff process is executed, the drive state of the third compressor, which is an operating compressor other than the first compressor, which is the operating compressor with the highest degree of superheat, is switched from the transmission state to the shutoff state. Drive force is not transmitted to the third compressor. Therefore, since the third compressor is at rest, it is possible to reduce the amount of heat transfer medium to the third compressor. Along with this, the amount of suction of the heat medium to the first compressor increases. As a result, since the supply amount (return amount) of refrigeration oil to the first compressor increases, the shortage of refrigeration oil in the first compressor can be reduced, and problems such as sealing failure and lubrication failure can be reduced. .

  The third compressor is not particularly limited as long as it is an operating compressor other than the first compressor. However, due to the execution of the shutoff process, the suction amount of the heat medium to the third compressor is reduced (becomes zero). Therefore, from the viewpoint of suppressing the possibility of causing shortage of refrigeration oil in the third compressor by executing the shutoff process, adopting the second compressor, which is the operating compressor with the lowest degree of superheat, as the third compressor Is preferred.

<Flow of specific processing>
The ECU (HP-ECU 110 and / or ENG-ECU 410) constituting the control device provided in the heat pump to which the sixth method is applied executes, for example, the algorithm represented by the routine shown in the flowchart of FIG. 6 Implement the method. The said routine is performed by a predetermined | prescribed short cycle, when CPU which comprises said ECU performs various arithmetic processing according to the program stored in ROM which comprises said ECU.

  The flowchart of FIG. 6 is the same as the flowcharts of FIGS. 3 to 5 except that the discharge amount ratio of the first compressor is increased by execution of the shutoff process in step S37. Therefore, the description of the process from step S31 to step S35 is omitted.

  The imbalanced overheat index value (ΔHd) calculated based on the first degree of superheat (Hd1) which is the highest degree of superheat and the second degree of superheat (Hd2) which is the lowest degree of heat is higher than the determination threshold (Hdth) If the large state (imbalanced overheated state) does not continue over the determination period (Pj) or more, the CPU determines "No" in step S36, returns to step S31 described above, and the routine Execute repeatedly.

  On the other hand, if the imbalanced overheat state continues over the determination period (Pj) or more, the CPU determines "Yes" in step S36, and proceeds to the next step S37. In step S37, the CPU corresponds to the first superheat degree (Hd1) in the total discharge amount which is the sum of the discharge amounts of the heat medium from the plurality of operating compressors (211 and 212) included in the compression system. The ratio (first ratio) of the first discharge amount, which is the discharge amount of the heat medium from the (first compressor), is increased.

  At this time, in the sixth method, as shown in step S37 in the flowchart of FIG. 6, the ratio (first ratio) of the first discharge amount to the total discharge amount is increased by executing the above-described shutoff process. .

  According to the above, the supply amount (return amount) of the refrigerator oil to the first compressor can be increased, and the shortage of the refrigerator oil in the first compressor can be reduced. As a result, for example, problems such as seal failure and lubrication failure occur in the first compressor, and the possibility that the heat medium may overheat to exceed the allowable temperature of the parts and the first compressor may be damaged is reduced. Ru.

  In the above, each of the plurality of compressors 211 and 212 has a clutch, and is belt-driven by the engine 400, and the heat pump electronic control unit (HP-ECU) 110 and the engine electronic control unit (ENG-ECU) 410 Has described the case where the control device is configured. However, the sixth method can be applied to any heat pump as long as at least a part of the plurality of compressors constituting the heat pump has a mechanism for switching between transmission and shutoff of driving force from the drive source. That is, at least a part of the plurality of compressors constituting the heat pump to which the sixth method is applied may be equipped with a mechanism such as a clutch, and the drive source of the compressor is not limited to the engine. It may be another drive source.

  The control method for the heat pump according to the first embodiment of the present invention (hereinafter, may be referred to as “first embodiment method”) will be described below. The configuration of the heat pump to which the embodiment method 1 is applied is the same as the configuration of the heat pump shown in FIGS. 1 and 2 described above.

  That is, since the heat pump according to the present embodiment is a gas heat pump (GHP) driven by a gas engine and the compressors 211 and 212 are belt driven by the engine 400, the rotational speeds of these two compressors are the same. It is. Further, the opening degree of the displacement control valve 291 of the compressor 211 is larger than the opening degree of the displacement control valve 292 of the compressor 212. For this reason, the suction amount of the heat medium is smaller in the compressor 211 than in the compressor 212. Therefore, the amount of supply (return amount) of refrigeration oil is also smaller in the compressor 211 than in the compressor 212.

  In addition, as described above, for example, between the compressor 211 and the compressor 212, variations in the degree of aged deterioration and / or deviation of the operation frequency due to the operating conditions or the like occur or the installation state of the heat pump ( For example, there may be an imbalance in the supply amount (return amount) of refrigeration oil due to the levelness or the like. As a result, the shortage of refrigeration oil in the compressor 211 may be promoted.

  If the amount of supply of refrigeration oil in the compressor 211 is less than the appropriate amount, the sealability (air tightness) in the compression stroke of the heat medium becomes insufficient, and for example, leakage of the heat medium occurs in the compression stroke. The heat transfer medium may be repeatedly compressed to excessively increase the temperature of the heat transfer medium. In addition, the lubricity of the sliding portion of the compressor may be insufficient, and the compressor 211 may be damaged, for example.

  Succeedingly, based on the detected discharge temperature (a value having a correlation with the temperature of the discharged heat medium) detected by the temperature sensor 501 provided at the discharge port of the compressor 211 (corresponding to the degree of overheating of the heat medium And the degree of superheat derived based on the detected discharge temperature detected by the temperature sensor 502 provided at the discharge port of the compressor 212 (the compressor 211 and the compressor 212 The imbalanced overheat index value, which is a value corresponding to the difference in the degree of overheating of the heat medium in the interval, becomes equal to or more than the predetermined determination threshold described above. That is, in this case, the compressor 211 is a first compressor, and the compressor 212 is a second compressor. If this state (i.e., the unbalanced overheat state) continues for a predetermined period or more, the controller decreases the opening degree of the displacement control valve 291 of the compressor 211 and opens the displacement control valve 292 of the compressor 212. Increase the degree. That is, in the present embodiment, both the valve closing process shown in (1) and the valve opening process shown in (2) described above are performed.

  As a result, the amount of suction of the heat medium to the compressor 211 increases, and the amount of suction of the heat medium to the compressor 212 decreases. As a result, the supply amount (return amount) of the refrigerator oil to the compressor 211 is increased. Therefore, the sealability (air tightness) in the compression stroke of the heat medium and the lubricity at the sliding portion of the compressor become insufficient, and the problems of excessive rise in temperature of the heat medium and breakage of the compressor are reduced. can do.

  The control method of the heat pump according to the second embodiment of the present invention (hereinafter, may be referred to as “the second embodiment method”) will be described below. The configuration of the heat pump to which the embodiment method 2 is applied is also basically the same as the configuration of the heat pump shown in FIGS. 1 and 2 described above. That is, the heat pump which concerns on a present Example is a gas heat pump (GHP) which makes a gas engine a drive source, and both compressors 211 and 212 are equipped with a clutch. The compressors 211 and 212 are belt driven by the engine 400.

  In this embodiment, the drive states of these two compressors are both in the transmission state (the clutch is connected) and the rotational speeds are the same. However, for example, due to the variation in the degree of aged deterioration occurring between the compressor 211 and the compressor 212 and / or the deviation of the operation frequency due to the operating conditions and the installation state of the heat pump (for example, horizontality etc.) It is assumed that there is an imbalance in the supply of refrigeration oil. In the present embodiment, it is assumed that a shortage of refrigeration oil has occurred in the compressor 211.

  As a result, also in the present embodiment, the degree of superheat introduced based on the detected discharge temperature detected by the temperature sensor 501 provided in the discharge port of the compressor 211 and the temperature sensor provided in the discharge port of the compressor 212 The imbalanced overheat index value derived based on the degree of superheat derived based on the detected discharge temperature detected by 502 becomes equal to or greater than the above-described predetermined determination threshold. That is, also in this case, the compressor 211 is a first compressor and the compressor 212 is a second compressor. When this state (imbalanced overheat state) continues for a predetermined period or more, the control device disengages the clutch of the compressor 212 while keeping the clutch of the compressor 211 engaged (while transmitting the driving force) (drive Shut off the power). That is, in the present embodiment, the blocking process shown in the above (5) is performed.

  On the other hand, as described above, the control device controls the rotational speeds and the like of the compressors 211 and 212 so as to achieve the total discharge amount of the heat medium according to the load of the heat pump. Therefore, when the ratio (first ratio) of the first discharge amount to the total discharge amount is increased as described above, the control device increases the rotational speed of the first compressor (that is, the compressor 211), As a result, the supply amount (return amount) of the refrigerator oil to the first compressor can be increased.

  As a result, the amount of suction of the heat medium to the compressor 212 decreases (becomes zero), and the amount of suction of the heat medium to the compressor 211 increases. As a result, the supply amount (return amount) of the refrigerator oil to the compressor 211 is increased. Therefore, the sealability (air tightness) in the compression stroke of the heat medium and the lubricity at the sliding portion of the compressor become insufficient, and the problems of excessive rise in temperature of the heat medium and breakage of the compressor are reduced. can do.

  If the imbalanced overheat index value, which is a value corresponding to the difference in the degree of overheating of the heat medium between the compressor 211 and the compressor 212, becomes smaller than the determination threshold value by the execution of the above process, If the predetermined period has elapsed after execution, or if the imbalanced overheat index value becomes less than the determination threshold due to the execution of the above processing and the predetermined period elapses after the execution of the above processing, the clutch of the compressor 212 is reengaged ( The driving force may be transmitted), and the control may be returned to the normal control of controlling the rotational speed and the like of the compressors 211 and 212 so as to achieve the total discharge amount of the heat medium according to the load of the heat pump.

  By the way, in the method of the second embodiment, the shutoff process is performed, and the clutch of the compressor 212 is disengaged (the driving force is interrupted). Therefore, as described above, immediately after the clutch of the compressor 212 is reengaged (the driving force is transmitted) and both the compressors 211 and 212 are returned to the normal control, the compressor 212 runs short of refrigerator oil. There is a risk of Therefore, after operating both of the compressors 211 and 212 as described above, the clutch of the compressor 211 may be disconnected (the driving force is cut off), and the operation of the compressor 211 may be stopped. In this case, the rotational speed of the compressor 212 is increased as a result of control by the control device according to the load of the heat pump. As a result, the heat medium and the refrigerator oil are supplied only to the compressor 212, and the shortage of the refrigerator oil in the compressor 212 is eliminated. Thereafter, for example, the clutch of the compressor 211 is reengaged (transfer of the driving force) on condition that the predetermined period has elapsed, the detected discharge temperature is stabilized, or both of them, and the like. It may return to the usual control which controls the rotation speed etc. of compressors 211 and 212 so that a total discharge amount may be achieved.

  By the way, for example, in the heat pump used for the air conditioner, when the refrigerator oil is properly returned from the circulation route of the indoor unit and / or the heat medium to the outdoor unit side (oil separator), the oil separator to the refrigerator oil The temperature in the circulation path on the suction side of the compressor after is returned is sufficiently higher than the temperature in the circulation path on the suction side of the compressor before the refrigerator oil is returned from the oil separator. However, for example, in the case where there is an indoor unit in a stopped state for a long period of time with the expansion valve in a throttled state, refrigeration oil stagnates in the circulation path of the indoor unit and / or heat medium. A shortage of refrigeration oil may occur. In such a case, the temperature difference before and after the refrigeration oil is returned from the oil separator in the circulation path on the suction side of the compressor becomes smaller.

  Therefore, it is known in the art that a so-called "oil return operation" is performed when the temperature difference is small or whenever a predetermined period (for example, 10 hours) elapses. The "oil return operation" refers to an operation in which the heat medium is circulated in a state where the expansion valves of all the indoor units are opened more than in normal operation, and the refrigerator oil is returned to the outdoor unit side together with the heat medium as a liquid. .

  Even if the above oil return operation is performed, the shortage of refrigeration oil in any of the compressors is not eliminated, and a value corresponding to the difference in the degree of overheating of the heat medium among the plurality of operating compressors. When a state in which a certain imbalance overheat index value is larger than a predetermined threshold continues, the heat pump control method according to the present invention may be implemented including the above-described embodiments and examples. Alternatively, the oil return operation may be performed independently of the heat pump control method according to the present invention.

  While certain embodiments have been described, and for purposes of illustrating the invention, certain configurations and examples have been described, sometimes with reference to the accompanying drawings, the scope of the invention is to be considered as illustrative of those embodiments. It should not be construed as being limited to the embodiments and examples, and it goes without saying that modifications can be made as appropriate within the scope of the matters described in the claims and the specification.

  DESCRIPTION OF SYMBOLS 100 ... Air conditioning apparatus, 110 ... Electronic controller for heat pumps (HP-ECU) 200: Outdoor unit, 210 ... Compression system, 211 and 212 ... Compressor, 213 ... Suction header, 214 ... Discharge header, 221 ... Buffer, 222, 223 and 224: strainer, 225: filter dryer, 230: oil separator, 240: four-way valve, 250: heat exchanger (outdoor unit), 251: electronic expansion valve, 260: accumulator, 270: oil bypass regulator valve, 281 ... high pressure switch (SW), 282 ... high pressure sensor, 283 ... outdoor temperature sensor, 284 ... indoor temperature sensor, 290 ... hot gas bypass valve, 291 and 292 ... capacity control valve, 291 p and 292 p ... bypass path, 300 ... indoor Machine, 310 ... electronic expansion valve, 320 ... heat exchanger (indoor unit), 400 ... Engine, 410 ... electronic control unit (ENG-ECU) for an engine, as well as 501 and 502 ... temperature sensor.

Claims (6)

A heat medium circulation path, a compression system disposed in the middle of the circulation path, a condenser, an expansion valve, an evaporator, and a control device for controlling the operating state of the compressor according to a load; Further, the compression system includes a plurality of compressors arranged in parallel, a suction pipe which is a path through which the heat medium sucked from the circulation path to the plurality of compressors flows, and a discharge from the plurality of compressors A control method of a heat pump, comprising: a discharge pipe which is a path through which the heat medium to be fed flows to the circulation path,
The heat pump further includes a temperature sensor for detecting a detected discharge temperature, which is a value having a correlation with the temperature of the heat medium discharged from each of the plurality of compressors,
The control device is based on the degree of overheating of the heat medium guided based on the detected discharge temperature in a state where two or more operating compressors, which are operating compressors among the plurality of compressors, are present. The first degree of superheat which is the superheat degree of the first compressor which is the working compressor having the highest value of the superheat degree which is the corresponding value, and the second compressor which is the working compressor having the lowest superheat degree which is the lowest An imbalanced overheat index value, which is a value corresponding to the difference in the degree of overheating of the heat medium between the first compressor and the second compressor, based on the second degree of superheat, which is the degree of superheat, When it is determined that the imbalanced superheated state, which is a state larger than a predetermined threshold, continues for a predetermined period or more, a total discharge amount that is the sum of the discharge amounts of the heat medium from the plurality of compressors Discharge amount of the heat medium from the first compressor Increasing the percentage of a certain first discharge quantity,
Heat pump control method. The control method of the heat pump according to claim 1, wherein
The controller is
The detected discharge temperature is used as the degree of superheat,
Calculating a difference between the first degree of superheat and the second degree of superheat as the imbalanced overheat indicator value;
Heat pump control method. The control method of the heat pump according to claim 1, wherein
The heat pump further includes a pressure sensor that detects a detected discharge pressure that is a value having a correlation with the pressure of the heat medium discharged from each of the plurality of compressors,
The controller is
Using the degree of discharge superheat obtained by subtracting the saturated vapor temperature of the heat medium at the detected discharge pressure from the detected discharge temperature as the degree of superheat;
Calculating a difference between the first degree of superheat and the second degree of superheat as the imbalanced overheat indicator value;
Heat pump control method. The heat pump control method according to any one of claims 1 to 3, wherein
When it is determined that the imbalanced overheat state has continued for at least the predetermined period, the control device may:
Located from a first downstream area which is a partial area of a first path which is a path through which the heat medium flows inside the first compressor to a partial area of the first path which is upstream of the first downstream area To the first bypass area, which is the path for returning the heat medium to the first upstream area, which is the partial area of the inner area of the suction pipe located upstream of the first area or the partial area The first compressor is provided with a first valve which is an interposed capacity control valve, and the opening degree of the first valve is decreased when the opening degree of the first valve is larger than the minimum opening degree. A valve closing process which is a process, and a third compressor which is the working compressor other than the first compressor is a partial area of a third path which is a path through which the heat medium flows inside the third compressor. A third downstream region to a partial region of the third path, It is a path for returning the heat medium to a third upstream area which is a partial area located upstream of the third downstream area or a partial area of the inner area of the suction pipe located upstream of the third path A third valve is provided with a third bypass path and a third valve, which is a displacement control valve interposed in the third bypass path, and the opening degree of the third valve is smaller than the maximum opening degree. Valve opening processing, which is processing to increase the opening degree,
Perform one or both of
Heat pump control method. The heat pump control method according to any one of claims 1 to 3, wherein
When it is determined that the imbalanced overheat state has continued for at least the predetermined period, the control device may:
The first compressor is configured to be able to change the rotational speed independently of the operating compressor other than the first compressor, and the rotational speed of the first compressor is smaller than the maximum speed. Acceleration processing, which is processing to increase the rotational speed of the first compressor, and the third compressor, which is the operating compressor other than the first compressor, independently of the operating compressor other than the third compressor. A process of decreasing the rotational speed of the third compressor or stopping the third compressor when the rotational speed is configured to be changeable and the rotational speed of the third compressor is greater than the minimum speed Or, when the third compressor is configured to be able to change the rotational speed independently of the working compressor other than the third compressor, and the rotational speed of the third compressor is the minimum speed In the process of stopping the third compressor Slow down processing,
Perform one or both of
Heat pump control method. The heat pump control method according to any one of claims 1 to 3, wherein
When it is determined that the imbalanced overheat state has continued for at least the predetermined period, the control device may:
The third compressor, which is the operating compressor other than the first compressor, is in a transmission state in which the driving force from the driving source is transmitted to the third compressor, and the driving force from the driving source is The third clutch is used when the third clutch is a mechanism that switches the drive state of the third compressor between the shutoff state, which is a state not being transmitted to the third compressor. 3) a shutoff process which is a process of switching the drive state of the compressor to the shutoff state;
To perform
Heat pump control method.

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