WO2017138167A1

WO2017138167A1 - Cooler and air conditioner

Info

Publication number: WO2017138167A1
Application number: PCT/JP2016/072727
Authority: WO
Inventors: 有賀　徹
Original assignee: シャープ株式会社
Priority date: 2016-02-08
Filing date: 2016-08-03
Publication date: 2017-08-17
Also published as: CN108603681A; JP2017141970A; JP6653588B2; CN108603681B

Abstract

Provided are a cooler and an air conditioner with which it is possible to appropriately prevent the device from reaching an overload operating state, even when an outside air temperature sensor and/or an outdoor heat exchanger temperature sensor is not provided. An air conditioner 1 is equipped with: a refrigeration cycle (cooling mechanism) having a compressor 52; a power calculation unit 22 that calculates power values for the compressor 52; and a rotational frequency control unit 21 that controls the rotational frequency of the compressor 52. The rotational frequency control unit 21 determines whether the refrigeration cycle is in an overload state on the basis of the power values calculated by the power calculation unit 22 and the rotational frequency of the compressor 52, and controls the rotational frequency of the compressor 52 on the basis of the determination result.

Description

Air conditioner and air conditioner

The present invention relates to a cooling device that performs a cooling operation using a heat pump, and an air conditioner that performs a cooling operation and a heating operation using a heat pump.

When performing indoor cooling, a cooling unit or an air conditioner using a heat pump system that combines gas compression and expansion and heat exchange is used. The heat pump type air conditioner and air conditioner are provided with a refrigeration cycle to which a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger are connected. The strength of the cooling operation is adjusted by inverter control of the motor speed of the compressor in the refrigeration cycle.

In such air conditioners and air conditioners, if the air conditioner is operated when the outside air temperature is high, such as in summer, the device may be overloaded. Operation of the compressor in an overload state may lead to damage of parts and the like. Therefore, in a conventional air conditioner, for example, when the outside air temperature exceeds 40 ° C., it is determined that the engine is overloaded, and the maximum frequency of the compressor is lowered so as not to exceed the refrigerant pressure limit. I have control. In order to protect the compressor, an overload relay that reacts to temperature or input current is added to the surface of the compressor, and when the compressor surface temperature or input current exceeds a predetermined value, Some measures are taken such as stopping.

Further, Patent Document 1 discloses a compressor control for simultaneously monitoring a compressor discharge temperature and a compressor input current and protecting the compressor in any operation state.

Japanese Patent Laid-Open No. 7-158984

As described above, in a conventional air conditioner, the temperature of an outdoor air temperature sensor or an outdoor heat exchanger is measured, and when these temperature sensors become a predetermined temperature or more, the apparatus is overloaded. The compressor is determined to be in a state. However, this method poses a problem of increased cost due to mounting various temperature sensors outside the room. Also, for example, if the configuration is such that the outside temperature sensor is not mounted in order to give priority to cost, it becomes impossible to strictly control the overload state of the compressor, and it becomes necessary to mount an outdoor heat exchanger having a capacity larger than ideal. .

Also, conventionally, there are air conditioners that employ a method of estimating an overload of a device using a current sensor. However, in other countries, there are some regions where the power situation is poor such as regions where voltage fluctuation is large, regions where voltage drop is large, and regions where only a low voltage is supplied (specifically, ASEAN region). In such areas where power conditions are poor, overload estimation using this method is a cause of false detection, so it is currently impossible to employ it.

Therefore, in the present invention, it is possible to appropriately suppress the device from being overloaded even when at least one of the outdoor temperature sensor and the outdoor heat exchanger temperature sensor is not provided, and when neither is provided. It aims at providing the air conditioner and air conditioner which can do.

The air conditioner according to the first aspect of the present invention includes a cooling mechanism having a compressor, a power calculation unit that calculates a power value of the compressor, a power value obtained by the power calculation unit, and the compressor And a rotation speed control unit that determines whether or not the cooling mechanism is in an overload state based on the rotation speed and controls the rotation speed of the compressor based on the determination result.

In the air conditioner, the rotation speed control unit may determine that the power value obtained from the power calculation unit is in an overload state when a power threshold value in the rotation speed of the compressor is exceeded. Good.

The power threshold may be set by calculating in advance a power value when the compressor is operated in an overload state at different environmental temperatures and at different rotational speeds. Alternatively, the air conditioner according to the present invention further includes an outdoor unit and an outside air temperature sensor that measures the temperature of the environment in which the outdoor unit is placed, and the rotational speed control unit is measured by the outside air temperature sensor. The power threshold may be set based on the measured temperature.

An air conditioner according to the second aspect of the present invention is an air conditioner including a cooling device having any one of the above-described configurations.

As described above, the air conditioner and the air conditioner according to the present invention determine whether or not the cooling mechanism is overloaded based on the rotation of the compressor and the power value. Therefore, even when at least one of the outdoor air temperature sensor and the outdoor heat exchanger temperature sensor is not provided, it is possible to appropriately suppress the compressor from being overloaded.

It is a block diagram which shows the internal structure of the air conditioner concerning one embodiment of this invention. It is a schematic diagram which shows the whole structure of the air conditioner concerning one embodiment of this invention. It is a flowchart which shows the flow of the rotation speed control of the compressor in the air conditioner shown in FIG. FIG. 3 shows a control flow of the compressor when the air conditioner starts cooling operation. It is a flowchart which shows the flow of the rotation speed control of the compressor in the air conditioner shown in FIG. FIG. 4 shows a control flow of the compressor during the cooling operation. It is a graph which shows an example of the relationship between the rotation speed and electric power value in the compressor in the air conditioner shown in FIG. It is a block diagram which shows the internal structure of the air conditioner concerning the 2nd Embodiment of this invention. It is a schematic diagram which shows the whole structure of the air conditioner concerning the 2nd Embodiment of this invention. It is a flowchart which shows the flow of the rotation speed control of the compressor in the air conditioner shown in FIG. It is a graph which shows an example of the relationship between the rotation speed and electric power value in the compressor in the air conditioner shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
In the first embodiment, an air conditioner using a heat pump will be described as an example of the air conditioner of the present invention. FIG. 1 shows an internal configuration of an air conditioner 1 according to the present embodiment. FIG. 2 shows the overall configuration of the air conditioner 1 according to the present embodiment. Note that the air conditioner 1 according to the first embodiment can perform both the heating operation and the cooling operation. However, particularly when performing the cooling operation, the air conditioner 1 is also an example of the air conditioner of the present invention. Equivalent to.
<Overall configuration of air conditioner>

First, the overall configuration and basic operation of the air conditioner 1 according to the present embodiment will be described with reference to FIG. In FIG. 2, the flow of the refrigerant (heat medium) during the cooling operation of the air conditioner 1 is indicated by a solid arrow, and the flow of the refrigerant (heat medium) during the heating operation of the air conditioner 1 is indicated by a broken arrow. Yes.

As shown in FIG. 2, the air conditioner 1 according to the present embodiment is a separate air conditioner, and mainly includes an indoor unit 10 and an outdoor unit 50. The air conditioner 1 is configured by connecting the indoor unit 10 and the outdoor unit 50 via

refrigerant pipes

57 and 58. Hereinafter, the outdoor unit 50, the indoor unit 10, and the

refrigerant pipes

57 and 58 will be described in detail.

(1) Outdoor unit The outdoor unit 50 mainly includes a casing 51, a compressor 52, a four-way valve 53, an outdoor heat exchanger 54, an expansion valve 55, an outdoor blower 56, a refrigerant pipe 57, a refrigerant pipe 58, and a two-way valve. 59, and a three-way valve 60. The outdoor unit 50 is installed outdoors.

The casing 51 includes a compressor 52, a four-way valve 53, an outdoor heat exchanger 54, an expansion valve 55, an outdoor fan 56, a refrigerant pipe 57, a refrigerant pipe 58, a two-way valve 59, a three-way valve 60, and a discharge temperature sensor 61. Etc. are stored.

The compressor 52 has a discharge pipe 52a and a suction pipe 52b. The discharge pipe 52a and the suction pipe 52b are connected to different connection ports of the four-way valve 53, respectively. During operation, the compressor 52 sucks low-pressure refrigerant gas from the suction pipe 52b, compresses the refrigerant gas to generate high-pressure refrigerant gas, and then discharges the high-pressure refrigerant gas from the discharge pipe 52a. In the present embodiment, a compressor whose capacity can be changed by inverter control is adopted as the compressor 52. A discharge temperature sensor 61 that measures the temperature of the refrigerant discharged from the compressor 52 is disposed in the discharge pipe 52a.

The four-way valve 53 is connected to the discharge pipe 52a and the suction pipe 52b of the compressor 52, the outdoor heat exchanger 54, and the indoor heat exchanger 12 through a refrigerant pipe. The four-way valve 53 switches the path of the refrigeration cycle according to a control signal transmitted from a control unit (not shown in FIG. 2) of the air conditioner 1 during operation. That is, the four-way valve 53 switches the path between the cooling operation state and the heating operation state.

Specifically, in the cooling operation state, the four-way valve 53 connects the discharge pipe 52a of the compressor 52 to the outdoor heat exchanger 54 and connects the suction pipe 52b of the compressor 52 to the indoor heat exchanger 12 (FIG. (See solid line arrow 2). On the other hand, in the heating operation state, the four-way valve 53 connects the discharge pipe 52a of the compressor 52 to the indoor heat exchanger 12 and connects the suction pipe 52b of the compressor 52 to the outdoor heat exchanger 54 (broken line in FIG. 2). See arrow).

The outdoor heat exchanger 54 has a large number of radiating fins (not shown) attached to a heat transfer tube (not shown) bent back and forth at both left and right ends, and functions as a condenser during cooling operation. It functions as an evaporator during heating operation. In addition, you may use a parallel flow type heat exchanger and a serpent type heat exchanger as a heat exchanger.

The expansion valve 55 is an electronic expansion valve whose opening degree can be controlled via a stepping motor, which will be described later, and one is connected to a two-way valve 59 via a refrigerant pipe 57 and the other is an outdoor heat exchanger 54. It is connected to the. The stepping motor of the expansion valve 55 operates according to a control signal transmitted from a control unit (not shown) of the air conditioner 1. The expansion valve 55 depressurizes the high-temperature and high-pressure liquid refrigerant flowing out from the condenser (the indoor heat exchanger 12 during heating and the outdoor heat exchanger 54 during cooling) during operation. At the same time, it plays the role of adjusting the amount of refrigerant supplied to the evaporator (the outdoor heat exchanger 54 during heating and the indoor heat exchanger 12 during cooling).

In addition, it is good also as a cycle structure which uses a capillary tube and makes constant throttling irrespective of the quantity of a refrigerant | coolant. In this case, the cycle can be stabilized (not shown) by operating the compressor with a variable rotational speed range slightly reduced by the inverter.

The outdoor blower 56 is mainly composed of a propeller fan and a motor. The propeller fan is rotationally driven by a motor and supplies outdoor outdoor air to the outdoor heat exchanger 54. The motor operates according to a control signal transmitted from a control unit (not shown) of the air conditioner 1.

The two-way valve 59 is disposed in the refrigerant pipe 57. The two-way valve 59 is closed when the refrigerant pipe 57 is removed from the outdoor unit 50 to prevent the refrigerant from leaking from the outdoor unit 50 to the outside.

The three-way valve 60 is disposed in the refrigerant pipe 58. The three-way valve 60 is closed when the refrigerant pipe 58 is removed from the outdoor unit 50 to prevent the refrigerant from leaking from the outdoor unit 50 to the outside. Further, when it is necessary to recover the refrigerant from the outdoor unit 50 or the entire refrigeration cycle (cooling mechanism) including the indoor unit 10, the refrigerant is recovered through the three-way valve 60.

(2) Indoor unit The indoor unit 10 is mainly comprised from the housing | casing 11, the indoor heat exchanger 12, and the indoor air blower 13. As shown in FIG.

The housing 11 houses an indoor heat exchanger 12, an indoor blower 13, an indoor heat exchanger temperature sensor 14, an indoor temperature sensor 15, a control unit 20 (see FIG. 1), and the like. Note that the indoor heat exchanger temperature sensor 14 does not necessarily have to be mounted. In this case, the compressor can be operated normally by controlling the rotation speed of the compressor with the inverter.

The indoor heat exchanger 12 is a combination of three heat exchangers like a roof covering the indoor blower 13 as shown in FIG. Each heat exchanger has a large number of heat radiating fins (not shown) attached to a heat transfer tube (not shown) bent back and forth at both left and right ends, and functions as a condenser during heating operation. During cooling operation, it functions as an evaporator. The indoor heat exchanger temperature sensor 14 measures the temperature of the indoor heat exchanger 12. It arrange | positions in the intermediate part vicinity of the piping of the indoor heat exchanger 12. FIG.

The indoor blower 13 is mainly composed of a cross flow fan and a motor. The cross flow fan is rotationally driven by a motor, sucks indoor air into the housing 11 and supplies the air to the indoor heat exchanger 12, and sends out the air exchanged by the indoor heat exchanger 12 into the room.

The indoor temperature sensor 15 measures the temperature of the room where the indoor unit 10 is installed. The indoor temperature sensor 15 is disposed, for example, in the vicinity of the outside air inlet of the housing 11.

The compressor 52, the four-way valve 53, the outdoor heat exchanger 54 and the expansion valve 55 of the outdoor unit 50, and the indoor heat exchanger 12 of the indoor unit 10 are sequentially connected by

refrigerant pipes

57 and 58, and a refrigerant cycle (refrigeration cycle). Cycle).

(3) Refrigerant piping The refrigerant piping 57 is thinner than the refrigerant piping 58, and the liquid refrigerant flows during operation. The refrigerant pipe 58 is thicker than the refrigerant pipe 57, and a gas refrigerant flows during operation. As the heat medium (refrigerant), for example, HFC type R410A or R32 is used.

<Basic operation of the air conditioner>
Hereinafter, the cooling operation and the heating operation of the air conditioner 1 according to the present embodiment will be described in detail.

(1) Cooling operation In the cooling operation, the four-way valve 53 is in the state indicated by the solid line in FIG. 2, that is, the discharge pipe 52 a of the compressor 52 is connected to the outdoor heat exchanger 54 and the suction pipe 52 b of the compressor 52. Is connected to the indoor heat exchanger 12. At this time, the two-way valve 59 and the three-way valve 60 are opened. In this state, when the compressor 52 is started, the gas refrigerant is sucked into the compressor 52 and compressed, and then sent to the outdoor heat exchanger 54 via the four-way valve 53, and the outdoor heat exchanger 54. Is cooled to become a liquid refrigerant. Thereafter, this liquid refrigerant is sent to the expansion valve 55, where it is depressurized and enters a gas-liquid two-phase state. The gas-liquid two-phase refrigerant is supplied to the indoor heat exchanger 12 via the two-way valve 59, cools the indoor air and evaporates to become a gas refrigerant. Finally, the gas refrigerant is sucked into the compressor 52 again via the three-way valve 60 and the four-way valve 53.

(2) Heating operation In the heating operation, the four-way valve 53 is in the state indicated by the broken line in FIG. 2, that is, the discharge pipe 52a of the compressor 52 is connected to the indoor heat exchanger 12, and the suction pipe 52b of the compressor 52 Is connected to the outdoor heat exchanger 54. At this time, the two-way valve 59 and the three-way valve 60 are opened. When the compressor 52 is started in this state, the gas refrigerant is sucked into the compressor 52 and compressed, and then supplied to the indoor heat exchanger 12 via the four-way valve 53 and the three-way valve 60, Air is heated and condensed to become a liquid refrigerant. Thereafter, the liquid refrigerant is sent to the expansion valve 55 via the two-way valve 59 and is decompressed to be in a gas-liquid two-phase state. The gas-liquid two-phase refrigerant is sent to the outdoor heat exchanger 54 and evaporated in the outdoor heat exchanger 54 to become a gas refrigerant. Finally, the gas refrigerant is sucked into the compressor 52 again via the four-way valve 53.

<About compressor operation control>
Subsequently, a control method for suppressing the operation of the compressor 52 in an overload state in the air conditioner 1 according to the present embodiment will be described with reference to FIGS. 1, 3, and 4. In FIG. 1, the internal structure of the air conditioner 1 is shown. In FIG. 1, the structural member relevant to the operation control of the compressor 52 is shown.

As shown in FIG. 1, the indoor unit 10 includes an indoor fan 13, an indoor temperature sensor 15, a storage unit 16, a display unit 17, a receiving unit 18, a control unit 20, and the like.

The storage unit 16 includes a ROM (read only memory) and a RAM (Random access memory). The storage unit 16 stores an operation program and setting data of the air conditioner 1 and temporarily stores a calculation result by the control unit 20.

Display unit 17 includes a liquid crystal display panel, an LED light, and the like. The display unit 17 displays the operation status, alarms, and the like of the air conditioner 1 based on the signal from the control unit 20. The receiving unit 18 receives an infrared signal transmitted when a remote controller (not shown) is operated.

The control unit 20 is connected to each component in the air conditioner 1 and controls them. The control unit 20 includes a rotation speed control unit 21 and a power calculation unit 22. The rotation speed control unit 21 controls the rotation speed of the compressor 52 based on each signal transmitted to the control unit 20.

The power calculation unit 22 calculates the power value of the compressor 52 based on the current value and voltage value of the compressor 52 measured by the ammeter 62 and the voltmeter 63. The power value can be calculated by, for example, multiplying the current value measured by the ammeter 62, the voltage value measured by the voltmeter 63, and a coefficient based on the power factor with respect to the rotation speed of the compressor 52. The power factor is measured in advance. Thus, CT-less power monitoring can be performed by calculating the power value using the power factor. Also, accurate power can be measured, especially when the compressor is rotating at a higher speed. The calculation (estimation) of the power value is not limited to this, and may be performed using another conventionally known method.

Also, the outdoor unit 50 is provided with a compressor 52, an outdoor fan 56, a discharge temperature sensor 61, an ammeter 62, a voltmeter 63, a timer 64, and the like.

The ammeter 62 measures the current flowing through the compressor 52. The current measurement in the ammeter 62 can be performed using, for example, a shunt resistor. The voltmeter 63 measures the voltage applied to the compressor 52. The voltmeter 63 can measure the voltage of the compressor 52 through, for example, a voltage dividing resistor. The timer 64 measures the operation time of the compressor 52. Note that the operation time of the compressor 52 may be measured using a timer (not shown) installed on the indoor unit 10 side instead of the timer 64.

FIG. 3 shows the flow of compressor control when the air conditioner 1 starts the cooling operation. First, the user operates the remote controller or the like to give an instruction to start the cooling operation to the air conditioner 1. The receiving unit 18 of the air conditioner 1 receives this instruction and transmits a signal instructing the control unit 20 to start the cooling operation.

When the control unit 20 receives the cooling operation start instruction signal, the control unit 20 determines whether or not to start the operation of the compressor 52 (step S11 in FIG. 3). Specifically, the control unit 20 receives information on the room temperature measured by the room temperature sensor 15 (for example, the temperature of air sucked into the indoor unit 10 from the room). Then, the control unit 20 determines whether or not the compressor 52 should be operated based on the transmitted room temperature information. Here, even when the compressor 52 is operated at the minimum number of revolutions, if the room temperature is lower than the temperature set by the user, the control unit 20 determines that the compressor 52 cannot be operated (NO in step S11). ). And the control part 20 maintains the stop state, without operating the compressor 52 (step S12).

On the other hand, when the control unit 20 determines that the operation of the compressor 52 may be started based on the transmitted room temperature information (YES in step S11), the control unit 20 operates the compressor 52. Start (step S13). Then, the compressor 52 gradually increases the rotation speed.

The refrigerant cycle is configured in about 3 minutes after the compressor 52 starts operation, and the pressure of the piping in the cycle is stabilized. Therefore, the timer 64 measures the time after the compressor 52 starts operation, and waits for a predetermined time (for example, 3 minutes) to elapse (step S14). After a predetermined time (for example, 3 minutes) has elapsed since the compressor 52 started operation (YES in step S14), the control unit 20 fixes the rotational speed of the compressor 52 to a predetermined value (step S15). Here, the predetermined rotational speed is set to a value lower than the rotational speed (the rotational speed threshold value) of the compressor 52 that is restricted during overload operation.

In step S15, the outdoor blower 56 is also maintained at a predetermined fan speed (initial fan rotation speed preset on the air conditioner 1 side). Further, the indoor blower 13 is also maintained at a predetermined fan speed (initial fan rotation speed preset on the air conditioner 1 side). However, the fan speed at the start of the operation of the outdoor blower 56 and the indoor blower 13 is not limited to this, and the fan speed based on the set temperature specified by the user may be used.

The rotation speed of the compressor 52 is fixed to a predetermined value, and after about 30 seconds have elapsed, the power value of the compressor 52 is measured (step S16). The power value is measured by the power calculation unit 22 in the control unit 20. The power calculation unit 22 calculates the power value by the method described above based on the current value and the voltage value measured by the ammeter 62 and the voltmeter 63.

Information on the calculated power value is transmitted to the rotation speed control unit 21 in the control unit 20. The rotation speed control unit 21 determines whether or not the transmitted power value is higher than the upper limit value (power threshold value) of power at the predetermined rotation speed (step S17). And when the electric power value of the compressor 52 is higher than an electric power threshold value, the rotation speed control part 21 judges that the refrigerating cycle is an overload driving | running state (namely, outdoor outdoor temperature is high) (it is YES at step S17). ). And the rotation speed control part 21 operates the compressor 52 with the specific upper limit rotation speed in the said electric power value (step S18). The specific upper limit rotational speed is a rotational speed set so that the pressure of the refrigerant staying in the piping of the refrigeration cycle does not exceed a reference value.

Here, the upper limit value (power threshold value) of power at a predetermined rotational speed is set by calculating in advance the power value when the compressor 52 is overloaded at different environmental temperatures and at different rotational speeds. FIG. 5 shows an example of a power threshold for a predetermined number of rotations of the compressor. In FIG. 5, the power threshold A is indicated by a broken line. A method for setting the power threshold A will be described later.

On the other hand, when the power value of the compressor 52 is equal to or less than the power threshold value in step S17, the rotation speed control unit 21 determines that the refrigeration cycle is not in an overload operation state (NO in step S17). In this case, the rotation speed control unit 21 cancels the setting of the specific upper limit rotation speed (step S19). Then, the rotation speed control unit 21 operates the compressor 52 at the rotation speed (maximum rotation speed) necessary for cooling the room temperature to the set temperature desired by the user (step S20).

When the air conditioner 1 starts the cooling operation, the compressor 52 is controlled according to the above flow.

Subsequently, the rotational speed control of the compressor 52 during the air-conditioner 1 is performing the cooling operation will be described with reference to FIG. FIG. 4 shows a flow of processing for determining the operation state of the compressor 52 (determination of whether or not it is an overload operation) during the cooling operation.

What is necessary is just to perform the overload determination of the refrigerating cycle during air_conditionaing | cooling operation at the timing when the rotation speed of a compressor is changed, or a predetermined time interval, for example. Alternatively, the operation may be performed while constantly monitoring the load state of the refrigeration cycle.

When the overload determination is started, first, the control unit 20 determines whether or not the operation of the compressor 52 may be continued (step S21). Specifically, the control unit 20 receives information on the room temperature measured by the room temperature sensor 15 (for example, the temperature of air sucked into the indoor unit 10 from the room). And the control part 20 judges whether the driving | operation of the compressor 52 should be continued based on the transmitted indoor temperature information. Here, even if the compressor 52 is operated at the minimum number of revolutions, if the room temperature is lower than the temperature set by the user, the control unit 20 determines that the compressor 52 cannot be operated (NO in step S21). ). And the control part 20 stops the driving | operation of the compressor 52 (step S22).

On the other hand, when the control unit 20 determines that the operation of the compressor 52 may be continued based on the transmitted room temperature information (YES in step S21), the power value of the compressor 52 is calculated ( Step S23). Similar to step S <b> 16 described above, the power value is calculated by the power calculation unit 22. Information on the calculated power value is transmitted to the rotation speed control unit 21.

Subsequently, the rotation speed control unit 21 acquires information on the rotation speed of the current compressor 52 (step S24). Then, the rotation speed control unit 21 determines whether or not the transmitted power value is higher than the upper limit value (power threshold value) of the power at the acquired rotation speed (step S25). And when the electric power value of the compressor 52 is higher than an electric power threshold value, the rotation speed control part 21 judges that the refrigerating cycle is an overload driving | running state (namely, outdoor outdoor temperature is high) (it is YES at step S25). ). And the rotation speed control part 21 operates the compressor 52 with the specific upper limit rotation speed in the said electric power value (step S26). The specific upper limit rotational speed is a rotational speed set so that the pressure of the refrigerant staying in the piping of the refrigeration cycle does not exceed a reference value.

On the other hand, when the power value of the compressor 52 is equal to or less than the power threshold value in step S25, the rotation speed control unit 21 determines that the refrigeration cycle is not in an overload operation state (NO in step S25). Note that a reduction in the power value of the compressor 52 below the power threshold means that the outside air temperature has decreased. In this case, the rotation speed control unit 21 cancels the setting of the specific upper limit rotation speed (step S27). Then, the rotation speed control unit 21 operates the compressor 52 at the rotation speed (MAX rotation speed) necessary for cooling the room temperature to the set temperature desired by the user (step S28).

By performing the processing in the flow as described above, the rotational speed control is performed so that the compressor 52 during the cooling operation is not overloaded. It should be noted that after the above series of processing is completed, it is determined whether or not the operation of the compressor 52 can be continued again, and the processing of FIG. 4 may be repeated while the cooling operation is continued. That is, the processing may be performed in a flow of returning to step S21 after step S26 or step S28.

Subsequently, a method for setting the power threshold in the air conditioner 1 of the present embodiment will be described with reference to FIG. First, the basic concept for setting the power threshold will be described.

In the case of refrigeration cycles of the same model equipped with the same compressor, the power consumption of the compressor increases as the outside air temperature increases when compared at the same rotation speed. Therefore, an experiment is performed in advance to measure the electric power when the compressor is operated at a predetermined rotational speed under a plurality of different outside air temperature environments, and the rotational speed (rpm) and electric power (w) as shown in FIG. Create a correlation graph. Then, an outside air temperature at which the refrigeration cycle is overloaded is estimated from the obtained graph, and a power value reference for the rotation speed is set as a power threshold value.

Referring to the graph obtained as described above, predicting the outside air temperature at that time from the information on the rotation speed of the compressor and the power value, and predicting whether or not the refrigeration cycle is overloaded. Can do. That is, during the cooling operation, information on the rotational speed and power value of the compressor is acquired, and by plotting these information in the graph of FIG. 5, the outside air temperature in the environment where the air conditioner 1 is installed is estimated. can do. Further, whether or not the operating state of the compressor is an overload state can be determined based on whether or not the plotted point is located above the power threshold A.

For example, in the example of the graph shown in FIG. 5, the compressor 52 is operated at each rotation speed of 4000 rpm, 4500 rpm, 5000 rpm, and 5500 rpm, and the power value at each rotation speed is measured. Furthermore, the measurement of the power value at each rotational speed is performed under different outside air temperatures (environmental temperatures) of 35 ° C., 40 ° C., and 43 ° C., for example. By plotting the results obtained under each condition in a graph of rotation speed (rpm) versus power (w), a graph as shown in FIG. 5 is obtained.

For example, in the case where control is performed to determine that the compressor is overloaded when the compressor is normally operated in an environment where the outside air temperature exceeds 40 ° C., as shown in FIG. 5, a correlation line at a temperature of 40 ° C. The vicinity is set as the power threshold A.

When such a power threshold A is set, in the rotation speed control shown in FIG. 3, when the predetermined rotation speed fixed at the start of operation is 4500 rpm, the power value calculated by the power calculation unit 22 is 1800 w or more. Suppose. In this case, since the calculated electric power value exceeds the electric power threshold A shown in FIG. 5, the rotation speed control unit 21 determines that the refrigeration cycle is in an overload operation state (that is, the outdoor air temperature is high). (YES in step S17). Then, the rotational speed control unit 21 operates the compressor 52 by reducing the set rotational speed of the compressor 52 from 5500 rpm (maximum rotational speed) to 4500 rpm (specific upper limit rotational speed) (step S18). Here, it has been confirmed in advance that 4500 rpm set as the specific upper limit rotational speed is a pressure that does not exceed the refrigerant limit pressure of the outdoor heat exchanger.

Next, an example of performing the rotational speed control shown in FIG. 4 when the power threshold A shown in FIG. 5 is set will be described. Here, as an example, the overload determination is performed again from the compressor operating state at the start of the above-described operation (the power value is 1800 w or more and the motor is operating at the specific upper limit rotational speed of 4500 rpm). explain.

For example, when the power value calculated in step S23 shown in FIG. 4 is 1600 w, the power threshold A at the rotation speed of 4500 rpm is about 1800 w (see FIG. 5), so the calculated power value is lower than the power threshold A. Value (NO in step S25). This means that the outside air temperature has decreased to about 35 ° C., for example. Therefore, the rotation speed control unit 21 cancels the specific upper limit rotation speed of 4500 rpm (step S27). As a result, the compressor 52 is operated at a maximum rotational speed of 5500 rpm, for example (step S28).

In this state, since the outside air temperature is reduced to about 35 ° C., it is estimated that the electric power remains at about 2000 w even if the rotational speed is increased to 5500 rpm. Since the power threshold value A at the rotational speed of 5500 rpm is about 2100 w, the compressor 52 can continue to operate at 5500 rpm without being overloaded.

In this state, the compressor 52 continues to operate, and at the next overload determination timing, for example, when the power value at the rotation speed of 5500 rpm exceeds 2100 w, the rotation speed control unit 21 indicates that the refrigeration cycle is in an overload state. Some determination is made (YES in step S25). Then, the operation is switched again to the operation at the specific upper limit rotation speed (step S26).

As described above, in the air conditioner 1 according to this embodiment, the power value of the compressor is estimated, and the refrigeration cycle is in an overload operation state based on the rotation speed of the compressor and the estimated power value. Judge whether or not. Specifically, the overload operation state is determined based on whether or not the estimated power value of the compressor exceeds a power threshold for the rotation speed at that time. When the estimated power value exceeds the power threshold, it is determined that the overload operation state is present. And when it is judged that it is an overload driving | running state, a compressor is operated by the specific upper limit rotation speed lower than the rotation speed based on preset temperature.

By controlling the compressor in this way, overload operation of the compressor can be suppressed. In the compressor control of the present embodiment, information on the outside air temperature and the temperature of the outdoor heat exchanger is not required. Therefore, installation of an outside air temperature sensor or an outdoor heat exchanger temperature sensor can be omitted.

<Second Embodiment>
In the second embodiment, an air conditioner that is further provided with an outside air temperature sensor in addition to the configuration of the first embodiment will be described. FIG. 6 shows an internal configuration of the air conditioner 100 according to the second embodiment. FIG. 7 shows an overall configuration of the air conditioner 100 according to the second embodiment.

As shown in FIG. 7, the air conditioner 100 according to the second embodiment is further provided with an outside air temperature sensor 106 in addition to the configuration of the air conditioner 1 of the first embodiment. About the structure of other than that, the same structure as the air conditioner 1 of 1st Embodiment is fundamentally applicable. Therefore, in the second embodiment, only parts different from the first embodiment will be described.

The outdoor temperature sensor 106 measures the temperature in the environment where the outdoor unit 50 is installed. The outside air temperature sensor 106 is attached to the surface of the housing 51 of the outdoor unit 50, for example. In the air conditioner 100 of the second embodiment, information on the outside air temperature can be acquired by the outside air temperature sensor 106.

If the outside air temperature and power value are known, the refrigerant pressure in the outdoor refrigeration cycle can be estimated. Since the refrigerant pressure in the refrigeration cycle can be estimated, the rotation speed control unit 21 can more accurately determine whether or not the compressor 52 can be operated within the specification range of the compressor 52. That is, in the air conditioner 100 of the second embodiment, the power threshold value for determining the overload state can be changed according to the information on the outside air temperature obtained from the outside air temperature sensor 106.

<About compressor operation control>
Subsequently, a control method for suppressing the overload operation of the compressor 52 in the air conditioner 100 according to the present embodiment will be described with reference to FIGS. 6 and 8. In FIG. 6, the internal structure of the air conditioner 100 is shown. In FIG. 6, the structural member relevant to the operation control of the compressor 52 is shown.

As shown in FIG. 6, the indoor unit 10 includes an indoor fan 13, an indoor temperature sensor 15, a storage unit 16, a display unit 17, a receiving unit 18, a control unit 20, and the like. In addition, the control unit 20 includes a rotation speed control unit 21, a power calculation unit 22, and the like. About these structures, the structure similar to the air conditioner 1 of 1st Embodiment is applicable.

Also, the outdoor unit 50 is provided with a compressor 52, an outdoor fan 56, a discharge temperature sensor 61, an ammeter 62, a voltmeter 63, an outdoor temperature sensor 106, and the like. About the structure other than the outside air temperature sensor 106, the same structure as the air conditioner 1 of 1st Embodiment is applicable.

FIG. 8 shows a flow of compressor control when the air conditioner 100 performs a cooling operation. First, the user operates the remote controller or the like to give an instruction for starting the cooling operation to the air conditioner 100. The receiving unit 18 of the air conditioner 100 receives this instruction, and transmits a signal instructing the control unit 20 to start the cooling operation.

When the control unit 20 receives the instruction signal to start the cooling operation, the control unit 20 determines whether or not to start the operation of the compressor 52 (step S31 in FIG. 8). Specifically, the control unit 20 receives information on the room temperature measured by the room temperature sensor 15 (for example, the temperature of air sucked into the indoor unit 10 from the room). Then, the control unit 20 determines whether or not the compressor 52 should be operated based on the transmitted room temperature information. Here, even if the compressor 52 is operated at the minimum number of revolutions, if the room temperature is lower than the temperature set by the user, the control unit 20 determines that the compressor 52 cannot be operated (NO in step S31). ). And the control part 20 maintains the stop state, without operating the compressor 52 (step S32).

On the other hand, when the control unit 20 determines that the operation of the compressor 52 may be started based on the transmitted room temperature information (YES in step S31), the control unit 20 operates the compressor 52. Let it begin. Then, the compressor 52 gradually increases the rotation speed.

The refrigerant cycle is configured in about 3 minutes after the compressor 52 starts operation, and the pressure of the piping in the cycle is stabilized. Therefore, a timer (not shown) in the air conditioner 100 measures the time after the compressor 52 starts operation and waits for a predetermined time (for example, 3 minutes) to elapse. After a predetermined time (for example, 3 minutes) has elapsed from the start of operation of the compressor 52, the control unit 20 measures the power value of the compressor 52 (step S33). The power value is measured by the power calculation unit 22 in the control unit 20. The power calculation unit 22 calculates the power value by the same method as in the first embodiment based on the current value and the voltage value measured by the ammeter 62 and the voltmeter 63. Information on the calculated power value is transmitted to the rotation speed control unit 21 in the control unit 20.

Next, the rotation speed control unit 21 acquires information on the outside air temperature transmitted from the outside air temperature sensor 106 to the control unit 20 (step S34). Subsequently, the rotation speed control unit 21 acquires information on the current rotation speed of the compressor 52 (step S35). And the rotation speed control part 21 determines whether the transmitted electric power value is higher than the upper limit value (for example, electric power threshold value B (refer FIG. 9)) in the acquired external temperature and the acquired rotation speed. (Step S36).

Here, when the power value of the compressor 52 is higher than the power threshold B, the rotation speed control unit 21 determines that the refrigeration cycle is in an overload operation state (YES in step S36). And the rotation speed control part 21 operates the compressor 52 with the specific upper limit rotation speed in the said electric power value (step S37). The specific upper limit rotational speed is a rotational speed set so that the pressure of the refrigerant staying in the piping of the refrigeration cycle does not exceed a reference value.

On the other hand, when the power value of the compressor 52 is equal to or lower than the power threshold B in step S36, the rotation speed control unit 21 determines that the refrigeration cycle is not in an overload operation state (NO in step S36). In this case, the rotation speed control unit 21 operates the compressor 52 at the rotation speed (MAX rotation speed) necessary for cooling the room temperature to the set temperature desired by the user (step S38).

After step S37 or S38, the process returns to step S31 again to determine whether or not the operation of the compressor 52 may be continued. Then, while the air conditioner 100 continues the cooling operation, the above-described series of processing is repeated.

In the air conditioner 100, the compressor 52 is controlled by the flow as described above.

Subsequently, a method for setting a power threshold in the air conditioner 100 of the second embodiment will be described with reference to FIG. First, the basic concept for setting the power threshold will be described.

When the refrigerant is warmed by an increase in outside air temperature, the refrigerant pressure increases and the refrigeration cycle is more likely to be overloaded. When operating the refrigeration cycle, the refrigerant pressure range is set in order to maintain the safety of the apparatus. By setting the pressure range, the refrigeration cycle is prevented from being overloaded. Further, the refrigerant is further compressed and the refrigerant pressure is increased by increasing the rotation speed of the compressor. Normally, during the cooling operation, the refrigerant reaches the upper limit pressure when the outside air temperature is 43 ° C. That is, when the outside air temperature exceeds 43 ° C., the refrigerant pressure may exceed the upper limit of the safe pressure range.

In the air conditioner 1 of the first embodiment in which the outside air temperature sensor is not provided, a method of predicting the outside air temperature based on the power value and the rotation speed has been taken. Therefore, in order to operate the refrigeration cycle safely, the power threshold A (see FIG. 5) is set based on the power value when the outside air temperature is about 40 ° C. As a result, a rotational speed that is slightly lower than the rotational speed that is actually overloaded is set as the specific upper limit rotational speed.

In contrast, in the second embodiment, an outside air temperature sensor 106 is provided. That is, in the air conditioner 100, in addition to the information on the power value and the rotation speed of the compressor 52, information on the outside air temperature can also be acquired. If the power value, the rotation speed, and the outside air temperature are known, the refrigerant pressure can be predicted. And the upper limit refrigerant | coolant pressure for suppressing the overload driving | operation of a compressor can be set according to the model of an air conditioner. This upper limit refrigerant pressure can be set to 4.5 mPa, for example.

Therefore, in the air conditioner 100 according to the present embodiment, the power threshold B is set so that the refrigerant pressure in the outdoor space is equal to or lower than the upper limit refrigerant pressure. FIG. 9 shows the power threshold B when the upper limit refrigerant pressure is specified as 4.5 mPa and the outside air temperature is 43 ° C. The power threshold B varies depending on the outside air temperature. For example, when the outside air temperature is 40 ° C., the power threshold value increases. That is, the power threshold B shown in FIG. 9 is shifted upward. Therefore, it is desirable to set the power threshold B in units of temperature at a predetermined interval. Thus, in the air conditioner 100 of this embodiment, a different power threshold can be set according to each temperature. Therefore, it is possible to more accurately determine the overload state, and it is possible to increase the rotational speed of the compressor to a rotational speed closer to the limit.

For example, in the example shown in FIG. 8, when the rotational speed is 5500 rpm, 2100 w is the upper limit of the power value, and when the rotational speed is 5000 rpm, 2000 w is the upper limit of the power value. The power threshold B shown in FIG. 9 is an example, and the present invention is not limited to this. The power threshold value can be changed as appropriate in accordance with the type and specifications of the air conditioner.

<Third Embodiment>
In the first embodiment described above, it is determined whether or not the refrigeration cycle is in an overload state based on the rotation speed and power value of the compressor. In the second embodiment, whether or not the refrigeration cycle is in an overload state is determined based on information on the outside air temperature in addition to the rotation speed and the power value. In the third embodiment, an example in which overload determination is performed based on other information in addition to the above information will be described.

In the air conditioner according to the third embodiment, the indoor temperature and the fan speed (number of rotations) of the indoor blower or the air volume conversion data are employed as additional information for performing overload determination. In FIG. 1, the whole structure of the air conditioner 200 which concerns on 3rd Embodiment is shown. The air conditioner 200 has the same configuration as the air conditioner 1.

The indoor temperature information is acquired by the indoor temperature sensor 15 and transmitted to the control unit 20. Further, the control unit 20 controls the operation of the indoor blower 13. Moreover, the control part 20 can acquire the information of the fan speed of the indoor air blower 13, and air volume conversion data.

Whether the refrigerating cycle is overloaded based on information on the indoor temperature and the fan speed of the indoor blower 13 in addition to the rotational speed and power value of the compressor 52. Judgment of whether or not. Therefore, more accurate overload determination can be performed.

For example, when the room temperature is higher than the standard temperature, the power value tends to increase. Moreover, when the air volume of the indoor blower is large, the power value tends to be small. For this reason, a correction value for the indoor temperature or the air flow rate of the indoor blower is obtained in advance, and by adding these information as factors for overload determination, more accurate overload determination is possible compared to overload determination based only on the power value. It can be performed. By including these additional factors in the overload determination, for example, the power threshold A (see FIG. 5) and the power threshold B (see FIG. 9) shift upward or downward.

<Fourth Embodiment>
In the first to third embodiments described above, the air conditioner has been described as an example. However, the present invention can also be realized with a cooling device. Therefore, as a fourth embodiment, an air conditioner will be described as an example. In FIG. 2, the whole structure of the air conditioner 300 which concerns on 4th Embodiment is shown. The air conditioner 300 has substantially the same configuration as the air conditioner 1. However, the air conditioner 300 performs only the cooling operation and does not perform the heating operation. That is, the air conditioner 300 has a configuration in which the refrigeration cycle is circulated only in the direction indicated by the solid arrow in FIG. About the other structure, the structure similar to the air conditioner 1 is applicable.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. Further, configurations obtained by combining the configurations of the different embodiments described in this specification with each other are also included in the scope of the present invention.

1: Air conditioner 10: Indoor unit 20: Control unit 21: Rotational speed control unit 22: Electric power calculation unit 50: Outdoor unit 52: Compressor 100: Air conditioner 106: Outside air temperature sensor 200: Air conditioner 300: Cooling Machine

Claims

A cooling mechanism having a compressor;
A power calculation unit for calculating a power value of the compressor;
It is determined whether or not the cooling mechanism is in an overload state based on the power value obtained by the power calculation unit and the rotation speed of the compressor, and based on the determination result, the rotation of the compressor is determined. An air conditioner including a rotation speed control unit that controls the number.
The said rotation speed control part determines that it is an overload state, when the electric power value obtained from the said electric power calculation part has exceeded the electric power threshold value in the rotation speed of the said compressor. Air conditioner.
The air conditioner according to claim 2, wherein the electric power threshold is set by calculating in advance an electric power value when the compressor is overloaded at different environmental temperatures and at different rotational speeds.
An outdoor unit, and an outdoor temperature sensor that measures the temperature of the environment in which the outdoor unit is placed,
The air conditioner according to claim 2, wherein the rotation speed control unit sets the power threshold based on a temperature measured by the outside air temperature sensor.
An air conditioner having the air conditioner according to any one of claims 1 to 4.