JP6111665B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus.

  Conventionally, a refrigeration apparatus using R32 as a refrigerant is known. For example, Patent Literature 1 (Japanese Patent Laid-Open No. 2001-194015) discloses an air conditioner using R32.

  By the way, in the refrigeration apparatus, in order to prevent operation with the refrigerant leaking from the refrigerant circuit (coolant shortage state), detection of the refrigerant shortage state (gas shortage state) may be performed. For example, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-162979), a temperature difference between the temperature of the heat exchanger and the ambient temperature is detected, and when the temperature difference is equal to or less than a certain value, it is determined that the refrigerant is insufficient. An example of stopping the compressor is disclosed.

  However, when the refrigerant shortage state is detected by detecting the temperature difference between the temperature of the heat exchanger and the ambient temperature as in Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-162979), the following problem is caused. There is.

  Depending on conditions, the refrigeration apparatus may be in a state where liquid refrigerant is stored in the outdoor heat exchanger or the compressor (refrigerant stagnation state). In the refrigerant stagnation state, it is difficult for the temperature difference between the temperature of the heat exchanger and the ambient temperature to occur for a while after the start of operation of the compressor. For this reason, the refrigeration apparatus may erroneously determine that the refrigerant stagnation state is a refrigerant shortage state and stop the compressor.

  As a countermeasure for avoiding such an erroneous determination, a method of not determining the refrigerant shortage state under a condition where the refrigerant stagnation state is likely to occur can be considered. However, when R32 is used as a refrigerant as in Patent Document 1 (Japanese Patent Laid-Open No. 2001-194015), the internal temperature of the compressor is likely to rise compared to the case where a refrigerant such as R410A is used, and a refrigerant shortage state is noticed. If the compressor continues to operate without the internal temperature, the internal temperature may reach a temperature at which the compressor is damaged.

  An object of the present invention is a refrigeration apparatus that uses R32 as a refrigerant, can detect a refrigerant shortage state without mistaking it as a refrigerant stagnation state, and has high reliability capable of preventing damage to a compressor in a refrigerant shortage state. It is to provide a refrigeration apparatus.

The refrigeration apparatus according to the first aspect of the present invention is a refrigeration apparatus that uses R32 as a refrigerant. The refrigeration apparatus includes a compressor, a condenser, an expansion mechanism, an evaporator, a first temperature detection unit, a compressor control unit, and a determination unit. The compressor sucks low-pressure refrigerant from the suction flow path, compresses the refrigerant, and discharges high-pressure refrigerant. The condenser condenses the high-pressure refrigerant discharged from the compressor. The expansion mechanism expands the high-pressure refrigerant that has exited the condenser. The evaporator evaporates the refrigerant expanded by the expansion mechanism. The first temperature detector detects the refrigerant temperature in the condenser or in the vicinity of the condenser. The compressor control unit activates the compressor by the first activation control at a predetermined condition, and activates the compressor by the second activation control at a normal time other than the predetermined condition. The determination unit determines whether or not the refrigerant is in a shortage state. The first start control is control in which the average rotational speed of the compressor is smaller than that of the second start control. A determination part determines whether it is a refrigerant | coolant insufficient state using the refrigerant | coolant temperature detected by a 1st temperature detection part, when a compressor is started by 1st starting control. The condenser is an indoor heat exchanger. The evaporator is an outdoor heat exchanger. The predetermined condition is a condition that the outside air temperature is lower than the predetermined temperature and the room temperature is higher than the outside air temperature by a predetermined temperature difference or more.

  Here, the compressor control unit has a second start-up control and a first start-up control that keeps the average rotational speed of the compressor lower than the second start-up control as the start-up control of the compressor. In the first start control, since the rise in the internal temperature of the compressor is suppressed to be lower than that in the second start control, the compressor is not easily damaged even if the compressor is operated for a long time in the first start control. Therefore, when the compressor is started by the first start control, the refrigerant shortage state is determined using the refrigerant temperature of the condenser (near), so that the refrigerant is not in a refrigerant shortage state such as a refrigerant stagnation state. Regardless, a state that is difficult to distinguish from a refrigerant shortage state in a short period is not mistaken for a refrigerant shortage state. As a result, it is possible to realize a highly reliable refrigeration apparatus that can accurately detect the refrigerant shortage state and prevent damage to the compressor.

Here, since the compressor is activated by the first activation control under the low outside air temperature and high room temperature conditions in which the refrigerant stagnation state is likely to occur, the refrigerant stagnation state is not mistaken as the refrigerant shortage state, and the refrigerant is insufficient. The state can be detected.

  The refrigeration apparatus according to the second aspect of the present invention is a refrigeration apparatus that uses R32 as a refrigerant. The refrigeration apparatus includes a compressor, a condenser, an expansion mechanism, an evaporator, a first temperature detection unit, a compressor control unit, and a determination unit. The compressor sucks low-pressure refrigerant from the suction flow path, compresses the refrigerant, and discharges high-pressure refrigerant. The condenser condenses the high-pressure refrigerant discharged from the compressor. The expansion mechanism expands the high-pressure refrigerant that has exited the condenser. The evaporator evaporates the refrigerant expanded by the expansion mechanism. The first temperature detector detects the refrigerant temperature in the condenser or in the vicinity of the condenser. The compressor control unit activates the compressor by the first activation control at a predetermined condition, and activates the compressor by the second activation control at a normal time other than the predetermined condition. The determination unit determines whether or not the refrigerant is in a shortage state. The first start control is control in which the average rotational speed of the compressor is smaller than that of the second start control. A determination part determines whether it is a refrigerant | coolant insufficient state using the refrigerant | coolant temperature detected by a 1st temperature detection part, when a compressor is started by 1st starting control. In the first activation control, the operation and the stop of the compressor are repeated a plurality of times.

Note that the stoppage of the compressor here includes not only stopping the compressor (a state in which the rotation speed of the compressor is 0) but also reducing the rotation speed of the compressor.

Here, in the first start-up control, the compressor is stopped, so the rise in the internal temperature of the compressor is suppressed to a low level, and it is difficult to be damaged even if the compressor is operated for a long time. Therefore, a state that is difficult to distinguish from the refrigerant shortage state in a short period of time despite being not in the refrigerant shortage state is not mistaken for the refrigerant shortage state. As a result, it is possible to accurately detect the refrigerant shortage state and prevent damage to the compressor.

The refrigeration apparatus according to the third aspect of the present invention is the refrigeration apparatus according to the first aspect or the second aspect , and the determination unit is configured to detect the first temperature detection unit when the compressor is activated by the second activation control. It is further determined whether or not there is a refrigerant shortage state using the refrigerant temperature detected in step (b).

  Here, at a normal time other than the predetermined condition, the refrigerant shortage state can be determined when the compressor is activated by the second activation control in which the average rotational speed is larger than that of the first activation control.

A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the third aspect , wherein the determination unit is configured such that the temperature change of the refrigerant temperature detected by the first temperature detection unit is When it is smaller than the assumed temperature change, it is determined that the refrigerant is in a shortage state.

  Here, the refrigerant shortage state can be determined using the temperature change of the refrigerant temperature in the condenser or in the vicinity of the condenser.

Fifth aspect refrigerating apparatus according to the present invention is the refrigeration apparatus according to a first view point, in the first activation control, compressor, a smaller rotation speed than the rotational speed of the second activation control compressor, It is operated for a longer time than the second activation control.

  Here, when the compressor is operated with the first start control, the increase in the internal temperature of the compressor is easily suppressed as compared with the case where the compressor is operated with the second start control. The compressor is operated for a longer time in the first start control than in the second start control, and the refrigerant shortage state is determined at that time, so that it is difficult to distinguish the refrigerant shortage state from the refrigerant shortage state in a short period of time. There is no misunderstanding. As a result, it is possible to accurately detect the refrigerant shortage state and prevent damage to the compressor.

On the other hand, under conditions where the refrigerant shortage condition is unlikely to occur, operating the compressor by the second start control ends the compressor start operation earlier than the first start control and shifts to the actual operation. it can be.

A refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to any one of the first to fifth aspects, further comprising a second temperature detection unit. The second temperature detection unit detects the discharge temperature of the refrigerant discharged from the compressor. The determination unit further determines whether or not the refrigerant is in a shortage state by further using the discharge temperature.

Here, by further using the discharge temperature of the compressor, the refrigerant shortage state can be more accurately determined .

In the refrigeration apparatus according to the first aspect of the present invention, the compressor control unit performs the second start-up control and the first start-up control that keeps the average rotation speed of the compressor lower than the second start-up control as the start-up control of the compressor. And having. In the first start control, since the rise in the internal temperature of the compressor is suppressed to be lower than that in the second start control, the compressor is not easily damaged even if the compressor is operated for a long time in the first start control. Therefore, when the compressor is started by the first start control, the refrigerant shortage state is determined using the refrigerant temperature of the condenser (near), so that the refrigerant is not in a refrigerant shortage state such as a refrigerant stagnation state. Regardless, a state that is difficult to distinguish from a refrigerant shortage state in a short period is not mistaken for a refrigerant shortage state. As a result, it is possible to realize a highly reliable refrigeration apparatus that can accurately detect the refrigerant shortage state and prevent damage to the compressor. In the refrigeration apparatus according to the first aspect of the present invention, the refrigerant shortage state can be detected without misidentifying the refrigerant stagnation state as the refrigerant shortage state.

  In the refrigeration apparatus according to the second aspect of the present invention, it is possible to accurately detect the refrigerant shortage state and prevent damage to the compressor.

In the refrigeration apparatus according to the third aspect of the present invention, when the compressor is activated by the second activation control in which the average rotation speed is larger than that of the first activation control at normal times other than the predetermined condition, Judgment can be made.

In the refrigeration apparatus according to the fourth aspect of the present invention, the refrigerant shortage state can be determined using the temperature change of the refrigerant temperature in the condenser or in the vicinity of the condenser.

In the refrigeration apparatus according to the fifth aspect of the present invention , it is possible to accurately detect the refrigerant shortage state and prevent damage to the compressor.

In the refrigeration apparatus according to the sixth aspect of the present invention, the refrigerant shortage state can be determined more accurately .

It is a schematic block diagram of the air conditioning apparatus which concerns on one Embodiment of the freezing apparatus of this invention. It is a block diagram of the air conditioning apparatus of FIG. It is a flowchart of the selection process of the starting control of the compressor of the air conditioning apparatus of FIG. It is a flowchart of the determination process of the refrigerant | coolant insufficient state of the air conditioning apparatus of FIG. It is a flowchart of the determination process of the refrigerant | coolant insufficient state of the air conditioning apparatus of FIG. In the air conditioning apparatus of FIG. 1, it is explanatory drawing for demonstrating the reason for using 1st starting control on the conditions (refrigerant stagnation condition) which a refrigerant | coolant stagnation state tends to generate | occur | produce. (A) depicts changes over time in the internal temperature of the compressor, the discharge temperature of the compressor, and the temperature of the condenser when the compressor is operated with the first start control and the second start control in a refrigerant shortage state. doing. (B) depicts changes over time in the internal temperature of the compressor, the discharge temperature of the compressor, and the temperature of the condenser when the compressor is started by the first start control and the second start control in the refrigerant stagnation state. doing. The horizontal axis in FIG. 5 is time, and the vertical axis is temperature. In FIG. 5, Tin1, Td1, and Ta1 are used as symbols indicating the internal temperature of the compressor, the discharge temperature of the compressor, and the refrigerant temperature of the condenser, respectively, when the compressor is operated by the first activation control. . In FIG. 5, Tin2, Td2, and Ta2 are used as symbols indicating the internal temperature of the compressor, the discharge temperature of the compressor, and the refrigerant temperature of the condenser, respectively, when the compressor is operated by the second activation control. ing.

  Hereinafter, an air conditioner 10 according to an embodiment of the refrigeration apparatus of the present invention will be described with reference to the drawings. Note that the following embodiments can be appropriately changed without departing from the gist of the present invention.

(1) Overall Configuration The air conditioner 10 as a refrigeration apparatus according to an embodiment of the present invention is an air conditioner that can be operated by switching between a cooling operation and a heating operation. However, the air conditioner 10 may not be operable by switching between the cooling operation and the heating operation. For example, the air conditioning apparatus 10 may be an air conditioning apparatus capable of performing only a heating operation.

  As shown in FIG. 1, the air conditioner 10 mainly includes an indoor unit 20, an outdoor unit 30, and a control unit 40. Here, only one indoor unit 20 is provided, but a plurality of indoor units 20 may be provided.

  The air conditioner 10 has a refrigerant circuit 1 filled with R32 as a refrigerant. The refrigerant circuit 1 has an indoor circuit 1 a accommodated in the indoor unit 20 and an outdoor circuit 1 b accommodated in the outdoor unit 30. The indoor side circuit 1a and the outdoor side circuit 1b are connected by a liquid refrigerant communication pipe 71 and a gas refrigerant communication pipe 72.

(2) Detailed Configuration (2-1) Indoor Unit The indoor unit 20 is installed in a room that is an air-conditioning target space of the air conditioner 10. The indoor unit 20 includes an indoor heat exchanger 21, an indoor fan 22, an indoor heat exchange temperature sensor 24, and an indoor temperature sensor 25.

  The indoor heat exchanger 21 is a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of heat transfer fins. During the cooling operation, the indoor heat exchanger 21 functions as an evaporator that evaporates refrigerant expanded by an outdoor expansion valve 36 described later, and cools indoor air. The indoor heat exchanger 21 functions as a condenser that condenses high-pressure refrigerant discharged from a compressor 31 described later during heating operation, and heats indoor air. The liquid side of the indoor heat exchanger 21 is connected to the liquid refrigerant communication pipe 71, and the gas side of the indoor heat exchanger 21 is connected to the gas refrigerant communication pipe 72.

  The indoor fan 22 is rotated by a fan motor, takes in indoor air, blows it to the indoor heat exchanger 21, and promotes heat exchange between the refrigerant flowing through the indoor heat exchanger 21 and the indoor air.

  The indoor heat exchanger temperature sensor 24 is a thermistor that detects the refrigerant temperature Ta in the indoor heat exchanger 21. The indoor heat exchanger temperature sensor 24 is attached to the indoor heat exchanger 21. The indoor heat exchanger temperature sensor 24 is an example of a first temperature detection unit that detects the refrigerant temperature Ta in the indoor heat exchanger 21 (condenser) when the indoor heat exchanger 21 functions as a condenser (during heating operation). It is.

  The room temperature sensor 25 is a sensor for detecting the room temperature Tr. The room temperature Tr is the temperature in the room that is the air-conditioning target space of the air conditioner 10. The room temperature sensor 25 is installed in a room suitable for detecting the room temperature Tr.

(2-2) Outdoor unit The outdoor unit 30 mainly includes a compressor 31, a four-way switching valve 33, an outdoor heat exchanger 34, an outdoor fan 35, an outdoor expansion valve 36, an outdoor heat exchange temperature sensor 37, and a discharge temperature sensor. 51 and an outside air temperature sensor 38. The compressor 31, the four-way switching valve 33, the outdoor heat exchanger 34, and the outdoor expansion valve 36 are connected by refrigerant piping.

(2-2-1) Connection of component equipment by refrigerant piping Connection by refrigerant piping of the component equipment of the outdoor unit 30 will be described.

  The suction port of the compressor 31 and the four-way switching valve 33 are connected by a suction pipe 81. The discharge port of the compressor 31 and the four-way switching valve 33 are connected by a discharge pipe 82. The four-way switching valve 33 and the gas side of the outdoor heat exchanger 34 are connected by a first gas refrigerant pipe 83. The outdoor heat exchanger 34 and the liquid refrigerant communication pipe 71 are connected by a liquid refrigerant pipe 84. The liquid refrigerant pipe 84 is provided with an outdoor expansion valve 36. The four-way switching valve 33 and the gas refrigerant communication pipe 72 are connected by a second gas refrigerant pipe 85.

(2-2-2) Compressor The compressor 31 drives the compression mechanism with a motor, thereby sucking low-pressure gas refrigerant from the suction pipe 81, and supplying the high-pressure gas refrigerant compressed by the compression mechanism to the discharge pipe 82. Discharge. Although the compressor 31 is a rotary compressor, it is not limited to this, For example, a scroll compressor may be sufficient.

  The compressor 31 is an inverter type compressor capable of changing the rotational speed N (the rotational speed of the motor of the compressor 31). The movement of the compressor 31 (start / stop of the compressor 31 and the rotation speed N of the compressor 31) is controlled by a compressor control unit 41b described later.

(2-2-3) Four-way switching valve The four-way switching valve 33 switches the flow direction of the refrigerant when the air-conditioning apparatus 10 is switched between the cooling operation and the heating operation. During the cooling operation, the discharge pipe 82 and the first gas refrigerant pipe 83 are connected, and the suction pipe 81 and the second gas refrigerant pipe 85 are connected (see the solid line in FIG. 1). On the other hand, during the heating operation, the discharge pipe 82 and the second gas refrigerant pipe 85 are connected, and the suction pipe 81 and the first gas refrigerant pipe 83 are connected (see the broken line in FIG. 1).

(2-2-4) Outdoor Heat Exchanger The outdoor heat exchanger 34 is a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of heat transfer fins. The outdoor heat exchanger 34 functions as a condenser that condenses the high-pressure refrigerant discharged from the compressor 31 by exchanging heat between the outdoor air and the refrigerant during the cooling operation. The outdoor heat exchanger 34 functions as an evaporator that evaporates the refrigerant expanded by the outdoor expansion valve 36 by exchanging heat between the outdoor air and the refrigerant during heating operation.

(2-2-5) Outdoor Fan The outdoor fan 35 is rotated by a fan motor and takes outdoor air into the outdoor unit 30. The taken outdoor air passes through the outdoor heat exchanger 34 and is finally discharged out of the outdoor unit 30. The outdoor fan 35 promotes heat exchange between the refrigerant flowing in the outdoor heat exchanger 34 and outdoor air.

(2-2-6) Outdoor Expansion Valve The outdoor expansion valve 36 is an example of an expansion mechanism, and is an electric expansion valve with a variable opening degree provided for adjusting the pressure and flow rate of the refrigerant flowing through the refrigerant circuit 1. is there. During the cooling operation, the outdoor expansion valve 36 expands the high-pressure refrigerant flowing from the outdoor heat exchanger 34 that functions as a condenser to the indoor heat exchanger 21 that functions as an evaporator. During the heating operation, the outdoor expansion valve 36 expands the high-pressure refrigerant flowing from the indoor heat exchanger 21 that functions as a condenser to the outdoor heat exchanger 34 that functions as an evaporator.

(2-2-7) Outdoor Heat Exchange Temperature Sensor The outdoor heat exchange temperature sensor 37 is a thermistor that detects the refrigerant temperature Tb in the outdoor heat exchanger 34. The outdoor heat exchange temperature sensor 37 is attached to the outdoor heat exchanger 34. The outdoor heat exchanger temperature sensor 37 is an example of a first temperature detector that detects the refrigerant temperature Tb in the condenser when the outdoor heat exchanger 34 functions as a condenser (during cooling operation).

(2-2-8) Discharge Pipe Temperature Sensor The discharge temperature sensor 51 is a thermistor for detecting the temperature of the refrigerant discharged from the compressor 31 (discharge temperature Td). The discharge temperature sensor 51 is an example of a second temperature detection unit. The discharge temperature sensor 51 is provided outside the compressor 31, more specifically, near the discharge port of the compressor 31 in the discharge pipe 82. The temperature detected by the discharge temperature sensor 51 is used for control of the compressor 31 (including protection control of the compressor 31) and the like.

(2-2-9) Outside air temperature sensor The outside air temperature sensor 38 is a sensor for detecting the outside air temperature To. The outside air temperature sensor 38 is installed in a place suitable for detecting the outside air temperature To outside the room.

(2-3) Control Unit The control unit 40 controls the movement of the air conditioner 10. In FIG. 2, the block diagram of the air conditioning apparatus 10 containing the control unit 40 is shown.

  The control unit 40 includes a control unit 41 made up of a microcomputer or the like, a storage unit 42 made up of a memory such as RAM or ROM, and an input unit 43 (remote control). The control unit 40 is electrically connected to each configuration of the indoor unit 20 and the outdoor unit 30. The configurations of the indoor unit 20 and the outdoor unit 30 connected to the control unit 40 include a compressor 31, a four-way switching valve 33, an outdoor fan 35, an outdoor expansion valve 36, an indoor fan 22, a discharge temperature sensor 51, an outdoor heat exchanger. A temperature sensor 37, an indoor heat exchange temperature sensor 24, an outside air temperature sensor 38, and an indoor temperature sensor 25 are included.

  The control unit 41 controls the air conditioner 10 by reading and executing the program stored in the storage unit 42. The control unit 41 exchanges control signals with the input unit 43 in order to operate the indoor unit 20. The control part 41 will start control at the time of starting of the air conditioning apparatus 10, if the starting command of the air conditioning apparatus 10 is received from the input part 43. FIG. The startup control of the air conditioner 10 includes startup control of the compressor 31. When the startup control of the air conditioner 10 is completed, the control unit 41 controls the air conditioning operation of the air conditioner 10. In the air conditioning operation of the air conditioner 10, the control unit 41 determines various types of the indoor unit 20 and the outdoor unit 30 according to operating conditions (for example, the degree of deviation between the indoor temperature Tr and the set temperature of the air conditioner 10). Control the equipment.

  In addition, the control part 41 has the determination part 41a and the compressor control part 41b as a function part. The determination unit 41a and the compressor control unit 41b will be described later.

(2-3-1) Control Unit (2-3-1-1) Determination Unit The determination unit 41a determines whether or not the air conditioner 10 is in a refrigerant shortage state when the air conditioner 10 is activated. More specifically, the determination unit 41a determines whether or not the air conditioner 10 is in a refrigerant shortage state when the compressor 31 is activated by the first activation control or the second activation control. The refrigerant shortage state refers to a state in which the refrigerant leaks from the refrigerant pipe or the like constituting the refrigerant circuit 1 and there is almost no refrigerant in the refrigerant circuit 1.

  The determination part 41a determines whether it is in a refrigerant | coolant insufficient state using the refrigerant | coolant temperature in a condenser. In other words, the determination unit 41a determines whether or not there is a refrigerant shortage state using the refrigerant temperature Tb detected by the outdoor heat exchange temperature sensor 37 during the cooling operation. Moreover, the determination part 41a determines whether it is a refrigerant | coolant insufficient state using the refrigerant | coolant temperature Ta detected by the indoor heat exchanger temperature sensor 24 if it is at the time of heating operation.

  More specifically, the determination unit 41a determines that the refrigerant is in shortage when the temperature change of the refrigerant temperature Tb detected by the outdoor heat exchanger temperature sensor 37 is smaller than the assumed temperature change during cooling operation. . When the temperature change of the refrigerant temperature Tb is smaller than the assumed temperature change, the refrigerant temperature Tb and the start of the compressor 31 are finished before the start control (first start control or second start control) of the compressor 31 is finished. This is a case where the temperature difference from the refrigerant temperature Tb at the start of control does not exceed the assumed temperature difference C. Moreover, the determination part 41a will determine with a refrigerant | coolant insufficient state, when the temperature change of the refrigerant | coolant temperature Ta detected by the indoor heat exchanger temperature sensor 24 is smaller than an assumed temperature change if it is at the time of heating operation. The case where the temperature change of the refrigerant temperature Ta is smaller than the assumed temperature change is the temperature between the refrigerant temperature Ta and the refrigerant temperature Ta at the start of the start-up control of the compressor 31 before the start-up control of the compressor 31 ends. This is a case where the difference does not exceed the assumed temperature difference C.

  If the refrigerant is insufficient, the refrigerant hardly flows through the refrigerant circuit 1, and therefore the temperature sensors 37 and 24 may not actually detect the temperature of the refrigerant. However, here, the detected values of the temperature sensors 37 and 24 in the refrigerant shortage state are also referred to as the refrigerant temperatures Tb and Ta, respectively.

  The reason why it is determined whether or not the refrigerant is in a shortage state using the refrigerant temperatures Tb and Ta detected by the temperature sensors 37 and 24 provided in the condenser is as follows.

  When the refrigerant is present in the refrigerant circuit 1 (when the refrigerant is not insufficient), when the compressor 31 is operated, the high-temperature and high-pressure refrigerant compressed by the compressor 31 becomes a condenser (the indoor heat exchanger 21 or the outdoor heat exchanger). 34), the temperature of the refrigerant flowing through the condenser gradually increases. On the other hand, in the refrigerant shortage state, since there is almost no refrigerant in the refrigerant circuit 1, the refrigerant is not compressed by the compressor 31, and the refrigerant hardly flows through the condenser. Therefore, the temperature of the condenser hardly changes. The determination unit 41a uses this difference to determine the refrigerant shortage state using the temperature changes of the refrigerant temperatures Tb and Ta in the condenser.

  The specific refrigerant shortage state determination process will be described later.

(2-3-1-2) Compressor Control Unit The compressor control unit 41b controls the start / stop of the compressor 31 and the rotational speed N of the compressor 31 (the rotational speed of the motor of the compressor 31).

  The compressor control unit 41 b performs activation control of the compressor 31 when the air conditioner 10 is activated. The start-up control of the compressor 31 is control of the compressor 31 when the determination unit 41a determines whether or not the air conditioner 10 is in a refrigerant shortage state.

  The compressor control unit 41b activates the compressor 31 by the first activation control during a refrigerant stagnation condition described later. Moreover, the compressor control part 41b starts the compressor 31 by 2nd starting control in normal time (at the time other than refrigerant | coolant stagnation conditions). Selection of the start control of the compressor 31 (selection of whether the start control of the compressor 31 is the first start control or the second start control) is a sub control unit of the compressor control unit 31. Selection is performed by the selection unit 41ba (see FIG. 2). The activation control selection process by the activation control selection unit 41ba will be described later.

  Moreover, the compressor control part 41b will perform control at the time of the air conditioning of the compressor 31, if the starting control of the compressor 31 is complete | finished. In the air conditioning control, the compressor 31 is controlled according to the operating conditions of the air conditioning operation of the air conditioner 10. For example, as control during air conditioning of the compressor 31, the compressor control unit 41 b controls the rotation speed N of the motor of the compressor 31 according to the degree of deviation between the room temperature Tr and the set temperature of the air conditioner 10.

  The first activation control is control for operating the compressor 31 at the first rotational speed N1. On the other hand, the second start-up control is control for operating the compressor 31 at the second rotation speed N2. The first rotation speed N1 is a rotation speed smaller than the second rotation speed N2. That is, the first activation control is control in which the average rotation speed of the compressor 31 is smaller than that in the second activation control.

  The first activation control is performed until the determination unit 41a determines that the air conditioner 10 is not in a refrigerant shortage state or the predetermined first activation time A1 ends. The second activation control is performed until the determination unit 41a determines that the air-conditioning apparatus 10 is not in a refrigerant shortage state or until the predetermined second activation time A2 ends. The first activation time A1 is longer than the second activation time A2.

  As described below, in the first activation control, the compressor 31 is operated for a longer time than in the second activation control.

  As described above, the determination unit 41a determines whether or not the refrigerant is in a shortage state based on whether or not the temperature change (more specifically, temperature increase) of the refrigerant temperature in the condenser is smaller than the assumed temperature change.

  If the refrigerant is not leaking from the refrigerant circuit 1 (not a refrigerant shortage state) and the conditions such as the room temperature, the outside air temperature, the operation time of the compressor 31 are the same, the first activation control and the second activation control are In the second start-up control in which the rotation speed N of the compressor 31 is large, the temperature rise of the refrigerant temperature in the condenser is larger. Therefore, when the compressor 31 is operated by the second activation control, it is determined that the air conditioner 10 is not in the refrigerant shortage state earlier than when the compressor 31 is operated by the first activation control. In other words, when the refrigerant is not in a shortage state, in the first activation control, the compressor 31 is operated for a longer time than in the second activation control.

  On the other hand, if the refrigerant leaks from the refrigerant circuit 1 (if the refrigerant is in a shortage state), the refrigerant temperature in the condenser hardly changes, so the first activation time A1 in the first activation control and the second in the second activation control. The start-up time A2 and the compressor 31 are operated. As described above, the first activation time A1 is longer than the second activation time A2. That is, in the refrigerant shortage state, in the first activation control, the compressor 31 is operated for a longer time than in the second activation control.

(2-3-2) Storage Unit The storage unit 42 stores a program to be executed by the control unit 41 and various information. The information stored in the storage unit 42 includes various types of information used by the determination unit 41a for determining the refrigerant shortage state. The information stored in the storage unit 42 includes various types of information used by the compressor control unit 41b for starting control of the compressor 31. The information stored in the storage unit 42 includes various types of information used by the activation control selection unit 41ba for selecting activation control of the compressor 31.

(2-3-3) Input Unit The input unit 43 is a remote controller for the air conditioning apparatus 10. The input unit 43 receives various inputs from the user of the air conditioning apparatus 10. Various inputs received from the user by the input unit 43 include a start / stop command for the air conditioner 10, an operation mode (heating mode / cooling mode) of the air conditioner 10, a set temperature of the air conditioner 10, and the like.

(3) Selection Process for Start Control of Compressor The start process for selecting control of the compressor 31 will be described below. The startup control selection process of the compressor 31 is a process of selecting whether to start the compressor 31 by the first startup control or the second startup control. The startup control selection process of the compressor 31 is mainly executed by the startup control selection unit 41ba. The selection process of the startup control of the compressor 31 will be described with reference to the flowchart of FIG.

  The selection process of the start control of the compressor 31 is performed immediately after the start command of the air conditioning apparatus 10 is input to the input unit 43. However, it is not limited to this, The selection process of the starting control of the compressor 31 may be implemented regularly (for example, every 10 minutes) while the operation of the air conditioning apparatus 10 is stopped, for example.

  In step S1, the activation control selection unit 41ba acquires the outside air temperature To. Specifically, the activation control selection unit 41ba acquires the detection value of the outside air temperature sensor 38 as the outside air temperature To. Thereafter, the process proceeds to step S2.

  In step S2, the activation control selection unit 41ba determines whether or not the outside air temperature To acquired in step S1 is lower than the reference outside air temperature B1. The reference outside air temperature B1 is stored in the storage unit 42. The reference outside air temperature B1 is, for example, −5 ° C. However, it is not limited to this. If it is determined that the outside air temperature To is lower than the reference outside air temperature B1, the process proceeds to step S3. If it is determined that the outside air temperature To is higher than the reference outside air temperature B1, the process proceeds to step S6.

  In step S3, the activation control selection unit 41ba acquires the room temperature Tr. Specifically, the activation control selection unit 41ba acquires the detection value of the room temperature sensor 25 as the room temperature Tr. Thereafter, the process proceeds to step S4.

  In step S4, the activation control selection unit 41ba determines whether or not the temperature difference (Tr−To) between the room temperature Tr and the outside air temperature To acquired in step S3 is equal to or greater than the reference temperature difference B2. That is, the activation control selection unit 41ba determines whether or not the indoor temperature Tr is higher than the outside air temperature To by the reference temperature difference B2 or more. The reference temperature difference B2 is stored in the storage unit 42. The reference temperature difference B2 is 30 ° C., for example. However, it is not limited to this. If it is determined that the temperature difference (Tr-To) is greater than or equal to the reference temperature difference B2, the process proceeds to step S5. If it is determined that the temperature difference (Tr-To) is less than the reference temperature difference B2, the process proceeds to step S6.

  In step S5, the activation control selection unit 41ba selects the first activation control as the activation control of the compressor 31.

  In step S <b> 6, the activation control selection unit 41 ba selects the second activation control as the activation control of the compressor 31.

  The activation control selection unit 41ba makes the determination in step S2 and step S4 so that the indoor temperature Tr and the outdoor air temperature To are set to the outdoor unit 30 side (the outdoor heat exchanger 34, the compressor 31 and the like) of the air conditioner 10. It is determined whether or not the liquid refrigerant is easily stored. That is, the activation control selection unit 41ba determines whether or not the refrigerant stagnation state is likely to occur (refrigerant stagnation condition) by performing the determinations in step S2 and step S4.

  Then, at the time of the refrigerant stagnation condition, the activation control selection unit 41ba selects the first activation control as the activation control of the compressor 31. During normal times that are not refrigerant stagnation conditions, the activation control selection unit 41ba selects the second activation control as the activation control of the compressor 31. Since the refrigerant stagnation condition is a condition that may occur in the cold season, the first activation control may be selected as the activation control of the compressor 31 during the heating operation.

(4) Refrigerant shortage state determination process The refrigerant shortage state determination process is performed when the air-conditioning apparatus 10 is started, more specifically, when the compressor 31 is started. The refrigerant shortage state determination process will be described with reference to the flowcharts of FIGS. 4A and 4B.

  Note that, as described above, since the first activation control is activation control that may be selected during the heating operation, here, the determination process for the refrigerant shortage state performed when the air-conditioning apparatus 10 starts the heating operation is performed. Will be described as an example. Also during the cooling operation, the refrigerant shortage state determination process is performed in the same manner as described below.

  In step S10, it is determined whether or not the startup control selected by the startup control selection process (see FIG. 3) of the compressor 31 is the first startup control. If it determines with it being 1st starting control, it will progress to step S21. On the other hand, if it is determined that it is not the first activation control (the second activation control), the process proceeds to step S31.

  In step S21, the refrigerant temperature in the condenser is acquired as the initial refrigerant temperature Tai. Specifically, the detected value of the indoor heat exchanger temperature sensor 24 immediately before the compressor 31 is started is acquired as the initial refrigerant temperature Tai. The initial detected temperature Tai is stored in the storage unit 42.

  In step S <b> 22, the compressor control unit 41 b starts the first activation control of the compressor 31. That is, in step S22, the compressor control unit 41b starts operating the compressor 31 at the first rotation speed N1. Thereafter, the process proceeds to step S23.

  In step S23, the refrigerant temperature in the condenser is acquired as the refrigerant temperature Ta. Specifically, the detected value of the indoor heat exchanger temperature sensor 24 is acquired as the refrigerant temperature Ta. Thereafter, the process proceeds to step S24.

  In step S24, a temperature difference ΔT (refrigerant temperature Ta−initial refrigerant temperature Tai) between the refrigerant temperature Ta acquired in step S23 and the initial refrigerant temperature Tai stored in the storage unit 42 is calculated. Thereafter, the process proceeds to step S25.

  In step S25, it is determined whether or not the temperature difference ΔT calculated in step S24 is greater than or equal to the assumed temperature difference C. The assumed temperature difference C is stored in the storage unit 42. The assumed temperature difference C is set to an appropriate value so as not to overlook the refrigerant shortage state due to the detection error of the indoor heat exchanger temperature sensor 24 and the like. If the temperature difference ΔT is greater than or equal to the assumed temperature difference C, the process proceeds to step S26. If the temperature difference ΔT is smaller than the assumed temperature difference C, the process proceeds to step S27.

  In step S26, the compressor control unit 41b determines that the refrigerant temperature is not insufficient (normal) because the temperature change of the refrigerant temperature Ta in the indoor heat exchanger 21 (condenser) is greater than or equal to the assumed temperature change. Then, the refrigerant shortage state determination process is terminated. When the refrigerant shortage state determination process ends in step S26, the compressor control unit 41b ends the first activation control of the compressor 31 and starts the air-conditioning control of the compressor 31. The air conditioning control of the compressor 31 is, for example, determining the rotational speed N of the compressor 31 using the degree of divergence between the room temperature Tr and the set temperature of the air conditioner 10, and the compressor 31 at the rotational speed N. It is control which drives.

  In step S27, the time t from when the compressor control unit 41b starts the first activation control of the compressor 31 is longer than the first activation time A1 (the value of time t is greater than the value of the first activation time A1). It is determined whether or not it is large. If it is determined that the value of time t is greater than the value of first activation time A1, the process proceeds to step S28. If it is determined that the time t is less than or equal to the first activation time A1, the process returns to step S23.

  In step S28, the compressor control unit 41b determines that the refrigerant is in a shortage state because the temperature change of the refrigerant temperature Ta in the indoor heat exchanger 21 (condenser) is smaller than the assumed temperature change. The determination process ends. When the refrigerant shortage state determination process is completed in step S28, the compressor control unit 41b stops the operation of the compressor 31 in order to prevent the compressor 31 from being damaged.

  The processing (step S31 to step S38) when it is determined in step S10 that the control is not the first start control (the second start control) will be described with reference to FIG. 4B. Since Steps S31 to S38 have many of the same points as the processing of Steps S21 to S28, only the differences will be mainly described.

  Since step S31 is the same as step S21, description thereof is omitted.

  In step S32, the compressor control unit 41b starts the second activation control of the compressor 31. That is, in step S32, the compressor control unit 41b starts operating the compressor 31 at the second rotation speed N2. Thereafter, the process proceeds to step S33.

  Steps S33 to S36 are the same as steps S23 to S36, and thus description thereof is omitted.

  In step S37, the time t from when the compressor control unit 41b starts the second activation control of the compressor 31 is longer than the second activation time A2 (the value of time t is greater than the value of the second activation time A2). It is determined whether or not it is large. If it is determined that the value of time t is greater than the value of second activation time A2, the process proceeds to step S38. If it is determined that the time t is less than or equal to the second activation time A2, the process returns to step S33.

  Since step S38 is the same as step S28, description thereof is omitted.

(5) Features of First Activation Control Here, features of the first activation control will be described. More specifically, a state in which liquid refrigerant is stored on the outdoor unit 30 side of the air conditioner 10 (so-called refrigerant stagnation state) while preventing damage to the compressor 31 by performing the first activation control. The reason why the refrigerant shortage state can be determined will be described. Here, the reason will be described using FIG. 5 while comparing the first activation control and the second activation control.

  FIG. 5A shows the internal temperature of the compressor 31, the discharge temperature of the compressor 31, and the indoor heat exchange when the compressor 31 is started by the first start control and the second start control in a refrigerant shortage state. The time change of the refrigerant temperature of the vessel 21 (condenser) is depicted. FIG. 5B shows the internal temperature of the compressor 31, the discharge temperature of the compressor 31, and the indoor heat exchange when the compressor 31 is started by the first start control and the second start control in the refrigerant stagnation state. The time change of the refrigerant temperature of the vessel 21 (condenser) is depicted. In FIG. 5, Tin 1, Td 1, and Ta 1 are used as symbols indicating the internal temperature of the compressor, the discharge temperature of the compressor, and the temperature of the indoor heat exchanger 21 when the compressor is operated in the first activation control, respectively. ing. In FIG. 5, Tin 2, Td 2, and Ta 2 are used as codes indicating the internal temperature of the compressor, the discharge temperature of the compressor, and the temperature of the indoor heat exchanger 21 when the compressor is operated in the second activation control. Each is used. Tth in FIG. 5 indicates the temperature threshold Tth. The temperature threshold value Tth means a temperature at which the compressor 31 is likely to be damaged when the internal temperatures Tin1 and Tin2 of the compressor 31 are equal to or higher than the temperatures.

  The refrigerant shortage state will be described with reference to FIG.

  When the operation of the compressor 31 is started, the internal temperatures Tin1 and Tin2 of the compressor 31 are more likely to rapidly increase in the refrigerant shortage state than in the refrigerant shortage state. On the other hand, in the refrigerant shortage state, even if the operation of the compressor 31 is started, the refrigerant temperatures Ta1 and Ta2 of the indoor heat exchanger 21 hardly change.

  In the second start-up control, the compressor 31 is operated at a higher rotation speed (second rotation speed N2) than in the first start-up control. Therefore, the rising speed of the internal temperature Tin2 is faster than the rising speed of the internal temperature Tin1. . When the compressor 31 is operated by the second activation control, the internal temperature Tin2 reaches the temperature threshold value Tth after time D1. Therefore, in order to prevent the compressor 31 from being damaged during the second activation control when the refrigerant is leaking from the refrigeration circuit 1, the second activation time A2 cannot be set to the time D1 or more. On the other hand, when the compressor 31 is operated by the first activation control, the internal temperature Tin1 reaches the temperature threshold value Tth after time D2. Therefore, a value close to the time D2 can be selected as the first activation time A1 within a range not exceeding the time D2.

  Next, the refrigerant stagnation state in FIG.

  In the refrigerant stagnation state, immediately after the operation of the compressor 31 is started, the refrigerant temperatures Ta1 and Ta2 of the indoor heat exchanger 21 hardly change.

  Therefore, at the time when the operation of the compressor 31 is started and the time D1 has elapsed due to the second activation control, the refrigerant temperature Ta2 has not increased by more than the assumed temperature difference C from the start of the second activation control. Therefore, when the compressor 31 is operated by the second activation control in which the second activation time A2 is shorter than the time D1, the refrigerant stagnation state is also determined as the refrigerant shortage state.

  On the other hand, when the compressor 31 is operated by the first activation control, initially, the refrigerant temperature Ta1 hardly changes, but the refrigerant temperature Ta1 starts to rise as time elapses. Then, the refrigerant temperature Ta1 rises by an estimated temperature difference C or more from the start point of the first start control before the time D2 elapses from the start of the first start control. Therefore, if the first activation time A1 is set to a value close to the time D2, the refrigerant stagnation state is not mistaken for the refrigerant shortage state.

  In addition, when the compressor control part 41b always starts the compressor 31 by 1st starting control, a refrigerant | coolant stagnation state is not mistaken for a refrigerant shortage state, but it is required for starting control of the compressor 31. There is a problem that time is always long.

  On the other hand, here, the first activation control is performed only in a condition where the refrigerant stagnation state is likely to occur (refrigerant stagnation condition). On the other hand, the second start control for operating the compressor 31 at the second rotational speed N2 (> first rotational speed N1) during normal times other than the refrigerant stagnation condition where the refrigerant temperature Ta is likely to change immediately after the compressor 31 is started. Done. As a result, at the normal time, the start-up control of the compressor 31 can be completed in a short time, and the air-conditioning operation can be started quickly.

(6) Features (6-1)
The air conditioning apparatus 10 of the present embodiment is a refrigeration apparatus that uses R32 as a refrigerant. The air conditioner 10 includes a compressor 31, an indoor heat exchanger 21 as a condenser, an outdoor expansion valve 36 as an expansion mechanism, an outdoor heat exchanger 34 as an evaporator, and a first temperature detection unit. The indoor heat exchanger temperature sensor 24, the compressor control part 41b, and the determination part 41a are provided. The compressor 31 sucks the low-pressure refrigerant from the suction pipe 81, compresses the refrigerant, and discharges the high-pressure refrigerant. The indoor heat exchanger 21 condenses the high-pressure refrigerant discharged from the compressor 31. The outdoor expansion valve 36 expands the high-pressure refrigerant that has exited the indoor heat exchanger 21. The outdoor heat exchanger 34 evaporates the refrigerant expanded by the outdoor expansion valve 36. The indoor heat exchanger temperature sensor 24 detects the refrigerant temperature Ta in the indoor heat exchanger 21. The compressor control unit 41b activates the compressor 31 by the first activation control during the refrigerant stagnation condition, and activates the compressor 31 by the second activation control at a normal time other than the refrigerant stagnation condition. The determination unit 41a determines whether or not the refrigerant is in a shortage state. The first activation control is control in which the average rotation speed of the compressor 31 is smaller than that in the second activation control. The determination unit 41a determines whether or not the refrigerant is in a shortage state using the refrigerant temperature Ta detected by the indoor heat exchanger temperature sensor 24 when the compressor 31 is activated by the first activation control.

  Here, the compressor control part 41b has 2nd start-up control and 1st start-up control which suppresses the average rotation speed of the compressor 31 lower than 2nd start-up control as start-up control of the compressor 31. FIG. In the first start control, since the rise in the internal temperature of the compressor 31 is suppressed to a lower level than in the second start control, even if the compressor is operated for a long time in the first start control, the compressor is not easily damaged. Therefore, when the compressor 31 is started by the first start control, the refrigerant shortage state is determined by using the refrigerant temperature Ta of the indoor heat exchanger 21, so that the refrigerant 31 is not in a refrigerant shortage state for a short period of time. Therefore, a refrigerant stagnation state that is difficult to distinguish from a refrigerant shortage state is not mistaken for a refrigerant shortage state. As a result, it is possible to realize the highly reliable air conditioner 10 that can accurately detect the refrigerant shortage state and prevent the compressor 31 from being damaged.

(6-2)
In the air conditioning apparatus 10 of the present embodiment, the determination unit 41a uses the refrigerant temperature Ta detected by the indoor heat exchanger temperature sensor 24 when the compressor 31 is activated by the second activation control, so that the refrigerant is in an insufficient condition. It is determined whether or not.

  Thereby, at the time other than the refrigerant stagnation condition, when the compressor 31 is activated by the second activation control in which the average rotation speed of the compressor 31 is larger than that of the first activation control, the refrigerant shortage state is determined. be able to. Therefore, at the normal time, the determination of the refrigerant shortage state can be completed earlier than when the compressor 31 is started by the first start control, and the air conditioner 10 can shift to the air conditioning operation in a short time. .

(6-3)
In the air conditioning apparatus 10 of the present embodiment, the determination unit 41a determines that the refrigerant is in a shortage state when the temperature change of the refrigerant temperature Ta detected by the indoor heat exchanger temperature sensor 24 is smaller than the assumed temperature change.

  Here, the refrigerant shortage state can be determined using the temperature change of the refrigerant temperature Ta in the indoor heat exchanger 21.

(6-4)
In the air conditioning apparatus 10 of the present embodiment, in the first activation control, the compressor 31 has a rotation speed (first rotation speed N1) smaller than the rotation speed (second rotation speed N2) of the compressor 31 in the second activation control. Thus, it is operated for a longer time than the second activation control.

  Here, when the compressor 31 is operated with the first activation control, the increase in the internal temperature of the compressor 31 is easily suppressed to be lower than when the compressor 31 is operated with the second activation control. By operating the compressor 31 for a longer time than the second activation control in the first activation control, and determining the refrigerant shortage state at that time, the refrigerant stagnation state is not misidentified as the refrigerant shortage state. As a result, it is possible to accurately detect the refrigerant shortage state and prevent the compressor 31 from being damaged.

  On the other hand, in the normal time when the refrigerant shortage state is unlikely to occur, the compressor 31 is operated by the second activation control to finish the activation of the compressor 31 earlier than the first activation control, and the air conditioning operation is started. Can be migrated.

(6-5)
In the air conditioner 10 of this embodiment, the condenser is the indoor heat exchanger 21 and the evaporator is the outdoor heat exchanger 34. The refrigerant stagnation condition in which the first activation control is performed as the activation control of the compressor 31 is a condition that the outside air temperature To is lower than the reference outside air temperature B1 and the indoor temperature Tr is higher than the outside air temperature To by the reference temperature difference B2 or more. .

  Here, since the compressor 31 is activated by the first activation control under the low outside air temperature and high room temperature conditions where the refrigerant stagnation state is likely to occur, the refrigerant stagnation state is not mistaken as the refrigerant shortage state. Can detect shortage.

(7) Modification Examples of the present embodiment are shown below. A plurality of modified examples may be appropriately combined.

(7-1) Modification A
In the above-described embodiment, the compressor 31 is activated by the first activation control at the time when the refrigerant stagnation state is likely to occur (at the time of the refrigerant stagnation condition), but is not limited thereto. The first activation control only needs to be performed in a condition where it is easy to generate a state that is difficult to distinguish from the refrigerant shortage state in a short period of time even though it is not in the refrigerant shortage state. For example, a condition in which a state that is difficult to distinguish from a refrigerant shortage state is likely to occur in a short period of time although it is not in a refrigerant shortage state is a cooling operation (the outdoor heat exchanger 34 functions as a condenser, and the indoor heat exchanger 1), the first start-up control may be performed during the cooling operation. In this case, the outdoor heat exchange temperature sensor 37 functions as a first temperature detection unit.

(7-2) Modification B
In the said embodiment, although the indoor heat exchanger temperature sensor 24 as a 1st temperature detection part was attached to the indoor heat exchanger 21, it is not limited to this. The 1st temperature detection part should just be a thing which can grasp | ascertain the temperature change of the refrigerant | coolant which flows through indoor heat exchanger 21 vicinity, for example, may be attached to the refrigerant | coolant piping of the indoor heat exchanger 21 vicinity.

(7-3) Modification C
In the above embodiment, the compressor 31 is operated at the first rotational speed N1 in the first startup control and the compressor 31 is operated at the second rotational speed N2 in the second startup control. However, the present invention is not limited to this. Absent. The first start control only needs to suppress the increase in the internal temperature of the compressor 31 in the refrigerant shortage state as compared with the second start control, so that the average rotation speed of the compressor 31 in the first start control is the second What is necessary is just to be smaller than the average rotation speed of the compressor 31 of start control.

  For example, the second start-up control is a control for increasing the rotation speed of the compressor 31 by E1 from the initial rotation speed N0 per unit time, and the first start-up control is performed by changing the rotation speed of the compressor from the initial rotation speed N0 per unit time. The control may be increased by E2 (E2 <E1).

(7-4) Modification D
Further, the second activation control may be control for operating the rotation speed of the compressor 31 at the second rotation speed N2, and the first activation control may be control for periodically changing the rotation speed N of the compressor 31.

  In this case, for example, the first activation control is performed by operating the compressor 31 at the second rotation speed N2 during the first time F1 (for example, 5 minutes) and during the second time F2 (for example, 3 minutes). The operation content of operating the compressor 31 at the rotation speed N1 (first rotation speed N1 <second rotation speed N2) is defined as one cycle, and this cycle is repeated a plurality of times (for example, three times) in the first start-up control. Is.

  In this case, for example, the first start-up control is performed by operating the compressor 31 at the second rotation speed N2 during the first time F1, and stopping the compressor 31 during the second time F2 (rotation speed N). It is also possible to repeat this cycle a plurality of times, with the operation content of “1” set to 0).

  That is, in the first activation control according to the present modification, the operation and pause of the compressor 31 are repeated a plurality of times. Note that the stop of the compressor 31 here includes not only stopping of the compressor (a state where the rotation speed of the compressor is 0) but also reducing the rotation speed N of the compressor 31.

  Here, in the first activation control, the compressor 31 is stopped, so that an increase in the internal temperature of the compressor 31 is suppressed to a low level, and even if the compressor 31 is operated for a long period of time, it is difficult to be damaged. Therefore, the refrigerant stagnation state is not mistaken for the refrigerant shortage state. As a result, it is possible to accurately detect the refrigerant shortage state and prevent the compressor 31 from being damaged.

(7-5) Modification E
In the above-described embodiment, the determination unit 41a determines the refrigerant shortage state using the temperature change of the refrigerant temperature Ta detected by the indoor heat exchanger temperature sensor 24, but is not limited thereto. For example, as in Patent Document 2 (2004-162979), the determination unit 41a is configured to provide a temperature difference between the refrigerant temperature Ta detected by the indoor heat exchange sensor and the indoor temperature Tr detected by the indoor temperature sensor 25. May be used to determine the refrigerant shortage state.

(7-6) Modification F
In the embodiment described above, the determination unit 41a determines whether or not the refrigerant is in a shortage state using only the refrigerant temperature Ta detected by the indoor heat exchanger temperature sensor 24, but is not limited thereto. . For example, the determination unit 41a may further determine whether or not the refrigerant is in a shortage state by further using the discharge temperature Td of the refrigerant discharged from the compressor 31 detected by the discharge temperature sensor 51.

  For example, in the refrigerant shortage state, the refrigerant is hardly supplied to the compressor 31, so that the refrigerant is hardly discharged from the compressor 31. Therefore, as shown in FIG. 5A, even if the internal temperature (Tin1, Tin2) of the compressor 31 rises, the discharge temperature (Td1, Td2) hardly changes. On the other hand, in the refrigerant stagnation state, as shown in FIG. 5B, the discharge temperature (Td1, Td2) increases as the internal temperature (Tin1, Tin2) of the compressor 31 increases.

  By using such a change in the discharge temperature Td and using the discharge temperature Td for the determination of the refrigerant shortage state, the refrigerant shortage state can be more accurately determined.

(7-7) Modification G
In the above embodiment, the activation control selection unit 41ba determines the magnitude relationship between the outside air temperature To and the reference outside air temperature B1, and the magnitude difference between the temperature difference between the room temperature Tr and the outside air temperature To and the reference temperature difference B2. Although the refrigerant stagnation condition is determined by using, it is not limited to this. For example, the refrigerant stagnation condition may be determined using a function having the outside air temperature To and the room temperature Tr as parameters.

(7-8) Modification H
In the above-described embodiment, when the determination unit 41a determines that the refrigerant is not insufficient, the compressor control unit 41b ends the first start control or the second start control of the compressor 31, but is not limited thereto. It is not something. For example, the compressor control unit 41b performs the first start control or the second start control until the end of the first start time A1 or the second start time A2 even after the determination unit 41a determines that the refrigerant shortage state has not occurred. You may continue.

  According to the present invention, in a refrigeration apparatus that uses R32 as a refrigerant, a highly reliable refrigeration apparatus that can detect a refrigerant shortage state without misidentifying it as a refrigerant stagnation state and can prevent damage to the compressor in the refrigerant shortage state. Can be provided.

10 Air conditioning equipment (refrigeration equipment)
21 Indoor heat exchanger (condenser, evaporator)
24 Indoor heat exchanger temperature sensor (first temperature detector)
31 Compressor 34 Outdoor heat exchanger (evaporator, condenser)
36 Outdoor expansion valve (expansion mechanism)
37 Outdoor heat exchange temperature sensor (first temperature detector)
41a Determination unit 41b Compressor control unit 51 Discharge temperature sensor (second temperature detection unit)
81 Suction pipe (suction channel)

JP 2001-194015 A JP 2004-162979 A

Claims (6)

A refrigeration apparatus (10) that uses R32 as a refrigerant,
A compressor (31) for sucking low-pressure refrigerant from the suction flow path (81), compressing the refrigerant and discharging high-pressure refrigerant;
A condenser (21, 34) for condensing the high-pressure refrigerant discharged from the compressor;
An expansion mechanism (36) for expanding the high-pressure refrigerant exiting the condenser;
An evaporator (34, 21) for evaporating the refrigerant expanded by the expansion mechanism;
A first temperature detector (24, 37) for detecting a refrigerant temperature in the condenser or in the vicinity of the condenser;
A compressor control unit (41b) for starting the compressor by a first start control at a predetermined condition and starting the compressor by a second start control at a normal time other than the predetermined condition;
A determination unit (41a) for determining whether or not the refrigerant is in a shortage state,
The first activation control is control in which the average rotation speed of the compressor is smaller than that of the second activation control,
The determination unit, when the compressor is activated by said first activation control, using the refrigerant temperature detected by the first temperature detection unit, determines whether the refrigerant shortage state,
The condenser (21) is an indoor heat exchanger,
The evaporator (34) is an outdoor heat exchanger,
The predetermined condition is that the outside air temperature is lower than the predetermined temperature and the room temperature is lower than the outside temperature.
It is a condition that the temperature difference is higher than
Refrigeration equipment. A refrigeration apparatus (10) that uses R32 as a refrigerant,
A compressor (31) for sucking low-pressure refrigerant from the suction flow path (81), compressing the refrigerant and discharging high-pressure refrigerant;
A condenser (21, 34) for condensing the high-pressure refrigerant discharged from the compressor;
An expansion mechanism (36) for expanding the high-pressure refrigerant exiting the condenser;
An evaporator (34, 21) for evaporating the refrigerant expanded by the expansion mechanism;
A first temperature detector (24, 37) for detecting a refrigerant temperature in the condenser or in the vicinity of the condenser;
A compressor control unit (41b) for starting the compressor by a first start control at a predetermined condition and starting the compressor by a second start control at a normal time other than the predetermined condition;
A determination unit (41a) for determining whether or not a refrigerant shortage state;
With
The first activation control is control in which the average rotation speed of the compressor is smaller than that of the second activation control,
The determination unit determines whether or not the refrigerant is in a shortage state using the refrigerant temperature detected by the first temperature detection unit when the compressor is activated by the first activation control.
In the first activation control, the operation and pause of the compressor are repeated a plurality of times.
Refrigeration equipment. The determination unit further determines whether or not the refrigerant is in a shortage state by using the refrigerant temperature detected by the first temperature detection unit when the compressor is activated by the second activation control.
The refrigeration apparatus according to claim 1 or 2. The determination unit determines the refrigerant shortage state when a temperature change of the refrigerant temperature detected by the first temperature detection unit is smaller than an assumed temperature change.
The refrigeration apparatus according to any one of claims 1 to 3. In the first activation control, the compressor is operated for a longer time than the second activation control at a rotation speed smaller than the rotation speed of the compressor in the second activation control.
The refrigeration apparatus according to claim 1. A second temperature detector (51) for detecting the discharge temperature of the refrigerant discharged from the compressor;
Further comprising
The determination unit further determines whether or not the refrigerant is in a shortage state by further using the discharge temperature.
The refrigeration apparatus according to any one of claims 1 to 5.

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