WO2018092203A1

WO2018092203A1 - Air conditioner

Info

Publication number: WO2018092203A1
Application number: PCT/JP2016/083920
Authority: WO
Inventors: 慎太郎穴井
Original assignee: 三菱電機株式会社
Priority date: 2016-11-16
Filing date: 2016-11-16
Publication date: 2018-05-24
Also published as: JP6664511B2; JPWO2018092203A1

Abstract

This air conditioner has: a refrigerant circuit formed by connecting a compressor, a condenser, a decompression device, and an evaporator with refrigerant piping; an air volume adjustment unit that has a blower for blowing air into the evaporator and that adjusts the air volume passing through the evaporator; and a control device for controlling the actions of the refrigerant circuit and the air volume adjustment unit. When the evaporation temperature falls below a freezing threshold, the control device computes, on the basis of the operation frequency of the compressor, an air volume setting value which indicates the air volume to be blown to the evaporator by the air volume adjustment unit, and increases the air volume that passes through the evaporator on the basis of the computed air volume setting value.

Description

Air conditioner

The present invention relates to an air conditioner equipped with an evaporator, and more particularly, to an antifreezing process for the evaporator during cooling operation.

For example, when an air conditioner performs cooling operation in an environment where the outdoor temperature is low, the refrigerant cooled by the low-temperature outside air flows into the evaporator, and the evaporation temperature is lowered, so that the water adhering to the evaporator is frozen. There are things to do. Since such freezing of the evaporator leads to a decrease in operating capability, techniques for suppressing the freezing of the evaporator have been conventionally proposed (see, for example, Patent Documents 1 and 2).

The air conditioner disclosed in Patent Document 1 includes a variable capacity compressor and an evaporator, and calculates an evaporation temperature from a detection value of a pressure sensor attached in the vicinity of the evaporator. And the air conditioner of patent document 1 is comprised so that the capacity | capacitance of a compressor may be reduced, if the value of the calculated evaporation temperature is less than a predetermined value. The air conditioner of Patent Document 2 includes a variable capacity compressor and an evaporator to which a temperature sensor is attached, and the evaporation temperature is monitored by the temperature sensor. And the air conditioner of patent document 2 is comprised so that the capacity | capacitance of a compressor may be reduced, if the detected value by a temperature sensor falls below a predetermined value. In some air conditioners, the refrigerant flowing into the evaporator is bypassed to another circuit, and the refrigerant flow rate is adjusted to prevent the evaporator from freezing.

Japanese Patent No. 2541172 Japanese Patent Laid-Open No. 7-103596

However, in the air conditioners of Patent Documents 1 and 2, when the evaporation temperature falls below a predetermined value, the capacity of the compressor is reduced, so that the capacity of the air conditioner decreases and the required capacity cannot be maintained. There are challenges. Further, even in an air conditioner that employs a method of bypassing the refrigerant flowing into the evaporator, the amount of refrigerant flowing into the evaporator is reduced, so that the capacity of the air conditioner is reduced.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an air conditioner that suppresses freezing of an evaporator without reducing its capacity.

An air conditioner according to the present invention includes a refrigerant circuit formed by connecting a compressor that compresses a refrigerant, a condenser that condenses the refrigerant, a decompression device that decompresses the refrigerant, and an evaporator that evaporates the refrigerant through a refrigerant pipe. The evaporator has an air blower that blows air, and includes an air volume adjustment unit that adjusts the air volume that passes through the evaporator, and a control device that controls the operation of the refrigerant circuit and the air volume adjustment unit. The freezing determination unit that determines whether or not the temperature is equal to or lower than the freezing threshold, and if the evaporation temperature is determined to be lower than or equal to the freezing threshold in the freezing determination unit, based on the operating frequency of the compressor, Based on the setting value calculation processing unit that calculates the air volume setting value indicating the amount of air blown to the evaporator and the air volume setting value calculated by the setting value calculation processing unit, the air volume that passes through the evaporator is increased. It has a work control unit.

According to the present invention, when the evaporation temperature is equal to or lower than the freezing threshold, the amount of air passing through the evaporator is increased, so there is no need to reduce the capacity of the compressor and the amount of refrigerant flowing into the evaporator. Freezing of the evaporator can be suppressed without reducing the capacity of the machine.

It is the schematic which illustrates the structure of the air conditioner which concerns on Embodiment 1 of this invention. FIG. 2 is a Ph diagram illustrating an operating state of a refrigeration cycle in the air conditioner of FIG. 1. It is a block diagram which shows the functional structure of the control apparatus which the air conditioner of FIG. 1 has. It is explanatory drawing which illustrates the relationship between the evaporation temperature in the air conditioner of FIG. 1, air volume, and the operating frequency of a compressor. It is a flowchart which shows the operation example at the time of the cooling operation of the air conditioner of FIG. It is the schematic which illustrates the structure of the air conditioner which concerns on Embodiment 2 of this invention. It is a block diagram which shows the functional structure of the control apparatus which the air conditioner of FIG. 6 has. It is the schematic which illustrates the structure of the air conditioner which concerns on Embodiment 3 of this invention. It is a block diagram which shows the functional structure of the control apparatus which the air conditioner of FIG. 8 has. It is explanatory drawing which illustrates the relationship between the evaporating temperature in the air conditioner of FIG. 8, air volume, and the operating frequency of a compressor. It is a flowchart which shows the operation example at the time of the cooling operation of the air conditioner of FIG. It is explanatory drawing which illustrates the other relationship of the evaporating temperature in the air conditioner of FIG. 8, an air volume, and the operating frequency of a compressor. It is the schematic which illustrates the structure of the air conditioner which concerns on Embodiment 4 of this invention. It is a block diagram which shows the functional structure of the control apparatus which the air conditioner of FIG. 13 has. It is explanatory drawing which shows the relationship between the evaporating temperature in the conventional air conditioner, the air volume, and the operating frequency of a compressor.

Embodiment 1 FIG.
FIG. 1 is a schematic view illustrating the configuration of an air conditioner according to Embodiment 1 of the present invention. FIG. 2 is a Ph diagram showing the operating state of the refrigeration cycle in the air conditioner of FIG. As shown in FIG. 1, the air conditioner 10 includes a compressor 21, a condenser 22, a decompression device 23, an evaporator 24, and an air volume adjustment unit 30. In the air conditioner 10, the compressor 21, the condenser 22, the decompression device 23, and the evaporator 24 are connected by the refrigerant pipe 20, and the refrigerant circuit 10A is formed. The refrigerant circuit 10A is filled with a refrigerant.

The compressor 21 sucks low-pressure gas refrigerant and compresses it into a high-pressure gas refrigerant, and is provided in an outdoor unit (not shown) installed outdoors. The compressor 21 may be capable of arbitrarily changing the operating frequency by inverter control. The compressor 21 may not have a function of changing the operating frequency, and may be a constant speed whose capacity can be adjusted by a bypass valve or the like.

The condenser 22 is composed of, for example, a fin-and-tube heat exchanger, and is provided in the outdoor unit. The condenser 22 condenses the high-pressure gaseous refrigerant sent from the compressor 21 into a high-pressure liquid refrigerant by exchanging heat with the external fluid. The external fluid used for heat exchange may be a gas such as air or a liquid such as water.

The decompression device 23 is composed of, for example, an electronic expansion valve, and expands and decompresses a high-pressure liquid refrigerant into a low-pressure gas-liquid two-phase refrigerant. However, the decompression device 23 is not limited to the electronic expansion valve, and may be any device having a function of decompressing the refrigerant, such as a capillary tube. The decompression device 23 may be provided in an outdoor unit, or may be provided in an indoor unit (not shown) installed indoors.

The evaporator 24 is composed of a fin-and-tube heat exchanger, for example, and is provided in the indoor unit. The evaporator 24 evaporates the low-pressure gas-liquid two-phase refrigerant flowing in from the decompression device 23 into the low-pressure gas refrigerant by exchanging heat with the air, and returns the refrigerant to the compressor 21. It is.

That is, the refrigerant circuit 10A compresses the refrigerant into a high-pressure gas state by the compressor 21 and sends it to the condenser 22. In addition, the refrigerant circuit 10 </ b> A condenses the refrigerant into a high-pressure liquid state by the condenser 22 and sends it to the decompression device 23. Further, the refrigerant circuit 10 </ b> A expands the refrigerant by the decompression device 23 to form a low-pressure gas-liquid two-phase state, and sends it to the evaporator 24. Then, the refrigerant circuit 10A evaporates the refrigerant by the evaporator 24 to obtain a low-pressure gas state, and sends the refrigerant in the low-pressure gas state to the compressor 21 again. The air conditioner 10 adjusts the indoor temperature using the refrigeration cycle as described above. Since the air conditioner 10 of the first embodiment is configured to perform the cooling operation, the indoor air is cooled by the evaporator 24.

The air volume adjusting unit 30 is attached to the evaporator 24 and adjusts the air volume passing through the evaporator 24. The air volume adjustment unit 30 has a blower 31 that blows air to the evaporator 24. The blower 31 includes a fan motor 31 a driven by an inverter, and a fan 31 b that rotates using the fan motor 31 a as a power source and blows air to the evaporator 24. That is, the fan motor 31a is for driving the fan 31b.

The blower 31 blows air to the evaporator 24 in order to exchange heat between the air and the low-pressure gas-liquid two-phase refrigerant of the evaporator 24. That is, in the air conditioner 10, the air blown by the blower 31 passes through the evaporator 24, and heat exchange between the refrigerant flowing in the evaporator 24 and the indoor air is promoted. The type of the blower 31 is not particularly limited, and a sirocco fan or a plug fan can be adopted as the blower 31. The blower 31 may be a push-in type or a pull-type type.

The air conditioner 10 includes a condenser pressure sensor 41, a condenser outlet temperature sensor 42, an evaporator inlet temperature sensor 43, an evaporator outlet temperature sensor 44, and a control device 50. The condenser pressure sensor 41 measures the condensation pressure Pcm that is the pressure of the condenser 22. In the example of FIG. 2, the refrigerant pressure between point b and point c corresponds to the condensation pressure. The condenser outlet temperature sensor 42 measures the condenser outlet temperature, which is the outlet temperature of the condenser 22. In the example of FIG. 2, the temperature of the refrigerant at the point c corresponds to the condenser outlet temperature.

The evaporator inlet temperature sensor 43 measures the evaporation temperature Te which is the temperature on the decompressor 23 side of the evaporator 24. In the example of FIG. 2, the temperature of the refrigerant between the points d and z corresponds to the evaporation temperature Te. The evaporator outlet temperature sensor 44 measures the evaporator outlet temperature, which is the temperature of the outlet of the evaporator 24. In the example of FIG. 2, the temperature of the refrigerant at point a corresponds to the evaporator outlet temperature.

The control device 50 controls the operation of the refrigerant circuit 10A and the air volume adjustment unit 30. The control device 50 includes an evaporator inlet enthalpy hri and an evaporator outlet enthalpy hro based on a predetermined refrigeration cycle as shown in FIG. 2, pressure data obtained from the condenser pressure sensor 41, a condenser outlet temperature sensor 42, an evaporator. Air conditioning control is executed based on the temperature data obtained from the inlet temperature sensor 43 and the evaporator outlet temperature sensor 44. That is, the control device 50 controls the compressor 21 and the pressure reducing device 23 based on the operating state of the refrigeration cycle in the air conditioner 10, calculates the refrigerant flow rate, calculates the air volume, and the fan motor 31a. Is controlled to drive the fan 31b.

FIG. 3 is a block diagram showing a functional configuration of a control device included in the air conditioner of FIG. As illustrated in FIG. 3, the control device 50 includes a storage unit 51, a condensation temperature calculation unit 52, a supercooling degree calculation unit 53, a superheat degree calculation unit 54, a freezing determination unit 55, and a set value calculation processing unit. 56 and an operation control unit 57. The storage unit 51 stores information on air physical properties, information on refrigerant physical properties, information on capacity calculation formulas, and the like. The information on the capability calculation formula is information indicating formula (1), formula (2), and the like described later. Further, the storage unit 51 stores a setting value table in which the capacity of the air conditioner 10 is associated with the air volume setting value indicating the air volume blown to the evaporator 24 by the air volume adjustment unit 30. Hereinafter, the capability of the air conditioner 10 is also referred to as device capability Qe.

In the setting value table of the first embodiment, a rotation frequency setting value indicating the rotation frequency of the blower 31 is stored as the air volume setting value. The rotational frequency set value is set for preventing the evaporator 24 from freezing. That is, in the set value table, the rotation frequency set value is associated with each of a plurality of capabilities that the air conditioner 10 can exhibit. More specifically, in the setting value table, a rotation frequency setting value is associated with each range of the capability Qe of the device. The set value table is configured such that the rotation frequency set value increases as the device capability Qe decreases. Therefore, when the air conditioner 10 exhibits a certain capability in the set value table, if the rotation frequency of the blower 31 is set to the rotation frequency set value corresponding to the capability, the evaporator 24 can be prevented from freezing. Can do.

The condensing temperature calculation unit 52 calculates the condensing temperature based on the condensing pressure Pcm measured by the condenser pressure sensor 41 and information on the physical properties of the refrigerant in the storage unit 51. In the example of FIG. 2, the temperature of the refrigerant between point x and point y corresponds to the condensation temperature.

The supercooling degree calculation unit 53 calculates the supercooling degree SC using the condenser outlet temperature measured by the condenser outlet temperature sensor 42 and the condensation temperature calculated by the condensation temperature calculation unit 52. . More specifically, the supercooling degree calculation unit 53 obtains the supercooling degree SC by subtracting the condenser outlet temperature from the condensation temperature.

The superheat degree calculator 54 calculates the superheat degree SH using the evaporation temperature Te measured by the evaporator inlet temperature sensor 43 and the evaporator outlet temperature measured by the evaporator outlet temperature sensor 44. . More specifically, the superheat degree calculation unit 54 obtains the superheat degree SH by subtracting the evaporation temperature Te from the evaporator outlet temperature.

The freezing determination unit 55 compares the evaporation temperature Te measured by the evaporator inlet temperature sensor 43 with a preset freezing threshold T and determines whether or not the evaporation temperature Te is equal to or lower than the freezing threshold T. It is. Thereby, the freezing determination part 55 determines whether the evaporator 24 has a possibility of freezing. The freezing threshold T is set to 0 ° C., for example. But the freezing threshold T should just be set to the temperature which can prevent the evaporator 24 from freezing, and may be set to temperature other than 0 degreeC based on the structure content of the air conditioner 10, a refrigerant | coolant physical property, etc. . In addition, the freezing determination unit 55 has a function of acquiring the evaporation temperature Te from the evaporator inlet temperature sensor 43 at predetermined time intervals and determining whether the evaporation temperature Te is equal to or lower than the freezing threshold T. is doing.

When the freezing determination unit 55 determines that the evaporation temperature Te is equal to or lower than the freezing threshold T, the set value calculation processing unit 56 sets the air volume setting value based on the capacity of the compressor 21, that is, the operating frequency of the compressor 21. Is calculated. In the first embodiment, the set value calculation processing unit 56 calculates a rotation frequency setting value indicating the rotation frequency of the blower 31 as the air volume setting value.

The set value calculation processing unit 56 includes an evaporation pressure calculation unit 56a, a refrigerant flow rate calculation unit 56b, a capacity calculation unit 56c, and an air volume calculation unit 56d. The evaporation pressure calculation unit 56a calculates the evaporation pressure Pe used to calculate the refrigerant flow rate Gr based on the evaporation temperature Te measured by the evaporator inlet temperature sensor 43 and the refrigerant physical property information in the storage unit 51. To do. In the example of FIG. 2, the refrigerant pressure between point d and point a corresponds to the evaporation pressure Pe.

The refrigerant flow rate calculation unit 56b calculates the refrigerant flow rate Gr using the evaporation pressure Pe calculated by the evaporation pressure calculation unit 56a. The refrigerant flow rate Gr is expressed by the following equation (1) by the displacement volume V of the compressor 21 and the density ρ of the refrigerant to be compressed. Here, the displacement volume V of the compressor 21 corresponds to the operating frequency of the compressor 21 and is stored in the storage unit 51 in advance. The density ρ of the refrigerant to be compressed is calculated by the refrigerant flow rate calculation unit 56b based on the evaporation pressure Pe and information on the physical properties of the refrigerant in the storage unit 51.

That is, the refrigerant flow rate calculation unit 56b obtains the density ρ of the refrigerant to be compressed based on the evaporation pressure Pe and the information on the refrigerant physical properties. And the refrigerant | coolant flow volume calculating part 56b calculates | requires the refrigerant | coolant flow volume Gr by integrating | accumulating the displacement volume V of the compressor 21, and the density (rho) of the refrigerant | coolant compressed based on Formula (1).

The capability calculation unit 56c calculates the capability Qe of the equipment using the refrigerant flow rate Gr obtained by the refrigerant flow rate calculation unit 56b. Here, with respect to the capability Qe of the device, the following equation (2) using the refrigerant flow rate Gr, the evaporator inlet enthalpy hr, and the evaporator outlet enthalpy hr is established.

That is, the capacity calculating unit 56c integrates the refrigerant flow rate Gr and the evaporator inlet / outlet enthalpy difference Δhr, which is a difference obtained by subtracting the evaporator inlet enthalpy hr from the evaporator outlet enthalpy hr, based on the equation (2). The device's ability Qe is obtained. In addition, since the capability Qe of an apparatus is calculated using the displacement volume V of the compressor 21, there exists a relationship between the capability Qe of an apparatus and the operating frequency of the compressor 21. FIG.

The air volume calculation unit 56d calculates the rotation frequency set value by comparing the capability Qe of the device calculated by the capability calculation unit 56c with the set value table. Further, the air volume calculation unit 56d has a function of outputting information on the calculated rotation frequency set value to the operation control unit 57.

The operation control unit 57 has a function of changing the rotation speed of the fan 31b by controlling the driving of the fan motor 31a. That is, the operation control unit 57 can adjust the air volume passing through the evaporator 24 in the air volume adjustment range R that is the range from the initial air volume value Afi to the maximum air volume value Afm by controlling the blower 31.

When the evaporator 24 is likely to freeze, the operation control unit 57 increases the rotation frequency of the blower 31 based on the information of the rotation frequency set value calculated by the set value calculation processing unit 56, and the evaporator The amount of air passing through 24 is increased. That is, the operation control unit 57 controls the drive of the fan motor 31a so that the rotation frequency of the blower 31 becomes the rotation frequency setting value when the evaporation temperature Te decreases to the freezing threshold T, and the rotation speed of the fan 31b is set. It is something to raise.

The operation control unit 57 controls the operating frequency of the compressor 21 according to the air conditioning load and the like, and adjusts the flow rate of the refrigerant circulating in the refrigerant circuit 10A. Further, the operation control unit 57 has a function of controlling the opening degree of the decompression device 23 according to the air conditioning load or the like when the decompression device 23 is an electronic expansion valve or the like whose opening degree can be adjusted.

FIG. 4 is an explanatory diagram illustrating the relationship between the evaporation temperature, the air volume, and the operating frequency of the compressor in the air conditioner of FIG. FIG. 4 illustrates the freeze prevention control in an environment where the outside air temperature decreases with time. As shown in FIG. 4, the air conditioner 10 can increase the amount of air passing through the evaporator 24 in the air amount adjustment range R when the evaporation temperature Te decreases to the freezing threshold T. Therefore, the air conditioner 10 can maintain the operating frequency of the compressor 21 even when the evaporation temperature Te decreases to the freezing threshold T. Therefore, according to the air conditioner 10, freezing of the evaporator 24 can be suppressed without reducing the capacity. In the first embodiment, the air volume corresponds to the rotational frequency of the blower 31. The air volume initial value Afi is an initial value of the rotational frequency of the blower 31 when the cooling operation is started, and the air volume maximum value Afm is a maximum value of the rotational frequency of the blower 31.

By the way, in FIG. 4, although the mode that the rotational frequency of the air blower 31 is raised in steps is shown as time passes, the air conditioner 10 is an environment where the outside air temperature rises with time, for example. Below, you may make it raise the rotational frequency of the air blower 31 in steps. Further, the air conditioner 10 may cause the blower 31 to repeatedly increase and decrease the rotational frequency, for example, in an environment where the outside air temperature repeatedly increases and decreases. That is, the air conditioner 10 may perform an increase process or a decrease process of the rotational frequency of the blower 31 according to a change in the outside air temperature, that is, a change in the capability Qe of the device.

The control device 50 may be provided in the indoor unit or may be provided in the outdoor unit. Further, the control device 50 may be constituted by two control devices in which the above functions are separated. In this case, one control device is provided in the indoor unit and the other control device is provided in the outdoor unit. May be.

The control device 50 can be realized by hardware such as a circuit device that realizes each of the above functions. For example, the control device 50 can be executed on a calculation device such as a microcomputer, a DSP (Digital Signal Processor), or a CPU (Central Processing Unit). It can also be realized as executed software. In addition, the storage unit 51 can be configured by a RAM (Random Access Memory) and a ROM (Read Only Memory), a PROM (Programmable ROM) such as a flash memory, or an HDD (Hard Disk Drive).

FIG. 5 is a flowchart showing an operation example during the cooling operation of the air conditioner 10 of FIG. With reference to FIG. 5, the freezing suppression control by the air conditioner 10 of this Embodiment 1 is demonstrated.

When the air conditioner 10 starts the cooling operation, the freezing determination unit 55 acquires the evaporation temperature Te from the evaporator inlet temperature sensor 43 (step S101). And the freezing determination part 55 determines whether there exists a possibility of freezing in the evaporator 24 by determining whether the evaporation temperature Te is below the freezing threshold T (step S102).

When the freezing determination unit 55 determines that the evaporating temperature Te is equal to or lower than the freezing threshold T (step S102 / Yes), the set value calculation processing unit 56 calculates the air volume setting value and provides information on the calculated air volume setting value. It outputs to the operation control part 57 (step S103). On the other hand, when the freezing determination unit 55 determines that the evaporation temperature Te is higher than the freezing threshold T (No in step S102), the set value calculation processing unit 56 returns to step S101.

The operation control unit 57 performs air volume adjustment so that the air volume passing through the evaporator 24 becomes the air volume setting value according to the information on the air volume setting value output from the set value calculation processing unit 56. That is, the operation control unit 57 controls the drive of the fan motor 31a to increase the rotational speed of the fan 31b. In this way, the operation control unit 57 increases the rotational frequency of the blower 31 and increases the air volume passing through the evaporator 24 to the air volume setting value (step S104).

After the air volume adjustment by the operation control unit 57, the freezing determination unit 55 stands by until the set time elapses (step S105 / No), and when the set time elapses (step S105 / Yes), the process returns to step S101. That is, the air conditioner 10 repeats a series of operations in steps S101 to S105.

5 shows an example of returning to step S101 when the freezing determination unit 55 determines that the evaporation temperature Te is higher than the freezing threshold T (step S102 / No), but is not limited thereto. Absent. For example, the freeze determination unit 55 may acquire the evaporation temperature Te again after a predetermined time elapses by the process of proceeding from No in step S102 to step S105, and perform a series of operations in steps S101 to S105. .

As described above, the air conditioner 10 according to the first embodiment increases the amount of air passing through the evaporator 24 when the evaporation temperature is equal to or lower than the freezing threshold T. Therefore, the capacity of the compressor 21 and the evaporator Since it is not necessary to reduce the refrigerant inflow to 24, freezing of the evaporator 24 can be suppressed without reducing the capacity of the air conditioner 10.

By the way, since the capability Qe of the device is calculated as described above, it changes according to a change in the outside air temperature. For example, when the outside air temperature decreases, the capacity Qe of the device also decreases, and when the outside air temperature increases, the capacity Qe of the device also increases. The outside air temperature changes from time to time. For example, when the daily change is observed, it decreases with time from daytime to nighttime and increases with time from dawn to daytime. In this regard, the control device 50 determines whether or not there is a risk of freezing every set time, and performs air volume adjustment when there is a risk of freezing. Therefore, the air conditioner 10 can raise the rotational frequency of the air blower 31 in steps in the situation where the outside air temperature decreases with time. Further, the air conditioner 10 can cope with a sudden change in the outside air temperature by setting the setting time short. That is, according to the air conditioner 10, it is possible to realize anti-freezing control that flexibly responds to changes in the outside air temperature.

In the first embodiment, the process of increasing the rotational frequency of the blower 31 when the evaporation temperature Te decreases to the freezing threshold T has been described. However, after the rotational frequency of the blower 31 is increased, a predetermined condition is satisfied. In such a case, the rotational frequency of the blower 31 may be lowered. For example, the control device 50 may lower the rotational frequency of the blower 31 when the state where there is no risk of freezing (the state of No in step S102) continues for a certain time or longer. That is, the set value calculation processing unit 56 calculates the rotation frequency set value with reference to the set value table or table information configured similarly to the set value table when a state where there is no fear of freezing continues for a certain period of time or longer. You may do it. Then, the operation control unit 57 reduces the air volume passing through the evaporator 24 by lowering the rotation frequency of the blower 31 based on the information of the rotation frequency set value calculated by the set value calculation processing unit 56. It may be. If it does in this way, since the rotation frequency of the air blower 31 can be lowered | hung according to the raise of external temperature, while preventing the freezing of the evaporator 24, the cost resulting from operation | movement of the air blower 31 can be reduced. it can.

Embodiment 2. FIG.
FIG. 6 is a schematic view illustrating the configuration of the air conditioner according to Embodiment 2 of the invention. FIG. 7 is a block diagram showing a functional configuration of a control device included in the air conditioner of FIG. Based on FIG. 6 and FIG. 7, the structure and operation | movement of the air conditioner which concerns on this Embodiment 2 are demonstrated. Constituent members equivalent to those of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

The air conditioner 110 according to the second embodiment includes an air volume adjustment unit 130, and a control device 150 that controls the operation of the refrigerant circuit 10A and the air volume adjustment unit 130. The air volume adjusting unit 130 includes a blower 31 and an air volume adjusting damper 32 attached to the evaporator 24. The air volume adjusting damper 32 is provided on the air path formed by the blower 31 and adjusts the air volume passing through the evaporator 24. The air volume adjusting damper 32 can adjust the air volume that passes through the installed air passage by the rotation of a single plate or the multi-blade damper that can adjust the air volume that passes through the installed air passage by opening and closing a plurality of blades. Butterfly damper.

In the setting value table stored in the storage unit 51 in the second embodiment, the rotation frequency setting value and the opening setting value indicating the opening of the air volume adjustment damper 32 are stored as the air volume setting value. . The rotational frequency setting value and the opening degree setting value are set in advance for preventing the evaporator 24 from freezing. That is, the set value table in the second embodiment is such that the capability Qe of the device, the rotation frequency set value, and the opening degree set value are associated with each other. More specifically, in the set value table, the rotation frequency set value and the opening set value are associated with each range of the capability Qe of the device. The set value table is configured such that when the device capability Qe decreases, the rotation frequency set value increases and the opening set value increases. Therefore, when the air conditioner 110 exhibits a certain capability in the set value table, the rotational frequency of the blower 31 is set to a set frequency corresponding to the capability, and the opening degree of the air volume adjustment damper 32 is set to the capability. If the opening setting value corresponding to is set, freezing of the evaporator 24 can be prevented.

As shown in FIG. 7, the control device 150 includes a storage unit 51, a condensation temperature calculation unit 52, a supercooling degree calculation unit 53, a superheat degree calculation unit 54, a freezing determination unit 55, and a set value calculation processing unit. 156 and an operation control unit 157. The set value calculation processing unit 156 calculates an air volume set value based on the operating frequency of the compressor 21 when the freezing determination unit 55 determines that the evaporation temperature Te is equal to or lower than the freezing threshold T. In the second embodiment, the set value calculation processing unit 156 calculates the air volume blown to the evaporator 24 via the air volume adjustment damper 32, that is, the opening setting value and the rotation frequency setting value, as the air volume setting value. To do.

The set value calculation processing unit 156 includes an evaporation pressure calculation unit 56a, a refrigerant flow rate calculation unit 56b, a capacity calculation unit 56c, and an air volume calculation unit 156d. The air volume calculation unit 156d calculates the opening setting value and the rotation frequency setting value by checking the capability Qe of the device calculated by the capability calculation unit 56c against the setting value table. Further, the air volume calculating unit 156d has a function of outputting the calculated opening setting value information and the rotation frequency setting value information to the operation control unit 157. The other configuration of the air volume calculating unit 156d is the same as that of the air volume calculating unit 56d of the first embodiment described above.

The operation control unit 157 adjusts the amount of air passing through the evaporator 24 based on the information on the opening set value and the information on the rotation frequency set value calculated by the set value calculation processing unit 56. That is, when the evaporation temperature Te decreases to the freezing threshold T, the operation control unit 157 is configured so that the rotation frequency of the blower 31 becomes the rotation frequency setting value and the opening degree of the air volume adjustment damper 32 becomes the opening setting value. The rotational frequency of the blower 31 and the opening degree of the air volume adjustment damper 32 are adjusted. In the second embodiment, the air volume corresponds to the rotational frequency of the blower 31 and the opening degree of the air volume adjusting damper 32.

Here, in the set value table, at least one of the opening set value and the rotation frequency set value changes for each capability Qe of each device. Therefore, one of the opening setting value and the rotation frequency setting value calculated by the air volume calculation unit 156d may be the same as the value at the time of determination by the freezing determination unit 55. That is, the operation control unit 157 performs at least one of the process of increasing the rotation frequency of the blower 31 and the process of increasing the opening degree of the air volume adjustment damper 32 when the evaporation temperature Te decreases to the freezing threshold T. As a result, the amount of air passing through the evaporator 24 is increased. Other configurations of the operation control unit 157 are the same as those of the operation control unit 57 of the first embodiment described above.

The operation of the air conditioner 110 is the same as the operation of the air conditioner 10 described based on FIG. For example, the air conditioner 110 can adjust both the rotation frequency of the blower 31 and the opening degree of the air volume adjustment damper 32 in steps S103 and S104 by adjusting data in the set value table. That is, according to the air conditioner 110, the anti-freezing control for adjusting any one of the rotational frequency of the blower 31 and the opening degree of the air volume adjustment damper 32, and the rotational frequency of the blower 31 and the opening degree of the air volume adjustment damper 32 are provided. It is possible to combine anti-freezing control that adjusts both of the above.

As described above, the air conditioner 110 according to the second embodiment increases the amount of air passing through the evaporator 24 when the evaporation temperature is equal to or lower than the freezing threshold T. Therefore, the capacity of the compressor 21 or the evaporator Since it is not necessary to reduce the refrigerant inflow to 24, freezing of the evaporator 24 can be suppressed without reducing the capacity of the air conditioner 110.

And the air conditioner 110 can adjust the rotation frequency of the blower 31 and the opening degree of the air volume adjustment damper 32. For this reason, according to the air conditioner 110, the opening degree of the air volume adjusting damper 32 is narrowed in advance by a predetermined amount, and when the evaporating temperature Te is first lowered to the freezing threshold T, the opening degree of the air volume adjusting damper 32 is increased. The freezing prevention control of increasing the rotation frequency of the blower 31 when the evaporation temperature Te is lowered to the freezing threshold T next time is increased. Moreover, according to the air conditioner 110, when the evaporation temperature Te falls to the freezing threshold T, the rotational frequency of the blower 31 or the opening degree of the air volume adjustment damper 32 is adjusted, or the rotational frequency of the blower 31 and the air volume adjustment damper are adjusted. Both of the opening degrees of 32 can be adjusted. That is, according to the air conditioner 110, the opening degree adjustment of the air volume adjustment damper 32 and the adjustment of the rotation frequency of the blower 31 can be combined, so that more flexible freezing prevention control can be realized.

By the way, in said description, when evaporation temperature Te falls to the freezing threshold T, when performing at least one of the process which raises the rotational frequency of the air blower 31, and the process which enlarges the opening degree of the air volume adjustment damper 32 is performed. Explained. However, at least one of the process of lowering the rotational frequency of the blower 31 and the process of reducing the opening of the airflow adjustment damper 32 when a predetermined condition is satisfied after increasing the volume of air passing through the blower 31 It is good to do. For example, the control device 150 performs at least one of a process of lowering the rotational frequency of the blower 31 and a process of reducing the opening of the air volume adjustment damper 32 when a state where there is no possibility of freezing continues for a certain time or longer. You may make it perform. About another effect, it is the same as that of the air conditioner 10 of Embodiment 1. FIG.

In the second embodiment, the fan motor 31a capable of controlling the rotation speed is exemplified, but the present invention is not limited to this. For example, the air conditioner 110 may have a fan motor that rotates at a constant speed instead of the fan motor 31a, and may be configured to adjust the air volume passing through the evaporator 24 only by the air volume adjusting damper 32. .

Embodiment 3 FIG.
FIG. 8 is a schematic view illustrating the configuration of an air conditioner according to Embodiment 3 of the present invention. FIG. 9 is a block diagram illustrating a functional configuration of a control device included in the air conditioner of FIG. About the structural member equivalent to Embodiment 1 and 2 mentioned above, description is abbreviate | omitted using the same code | symbol.

As shown in FIGS. 8 and 9, the air conditioner 210 according to the third embodiment includes a control device 250 that controls the operation of the refrigerant circuit 10A and the air volume adjustment unit 30. The control device 250 includes a storage unit 51, a condensation temperature calculation unit 52, a supercooling degree calculation unit 53, a superheat degree calculation unit 54, a freezing determination unit 55, a set value calculation processing unit 256, and an operation control unit 257. And an air volume determination unit 258.

In the storage unit 51 according to the third embodiment, a rotation frequency setting value as an air volume setting value and an operation frequency setting value indicating the operation frequency of the compressor 21 are stored. The rotational frequency set value and the operating frequency set value are set in advance for preventing the evaporator 24 from freezing. More specifically, in the storage unit 51, as a setting value table, a rotation setting value table in which the device capability Qe and the rotation frequency setting value are associated, and a device capability Qe and the operation frequency setting value are associated. An operation set value table is stored. In the operation setting value table, an operation frequency setting value is associated with each range of the capability Qe of the device. The operation set value table is configured such that the operation frequency set value decreases as the device capability Qe decreases.

The air volume determination unit 258 compares the current air volume with the maximum air volume value Afm, which is the maximum air volume that can be blown by the blower 31, and determines whether or not the current air volume has reached the maximum air volume value Afm. It is.

The set value calculation processing unit 256 includes an evaporation pressure calculation unit 56a, a refrigerant flow rate calculation unit 56b, a capacity calculation unit 56c, an air volume calculation unit 56d, and an operating frequency calculation unit 256e. When the air volume determination unit 258 determines that the current air volume is less than the maximum air volume value Afm, the set value calculation processing unit 256 rotates the capacity Qe of the device calculated by the capacity calculation unit 56c. The rotational frequency set value is calculated in light of the set value table. The air volume calculation unit 56d has a function of outputting information on the calculated rotation frequency setting value to the operation control unit 257.

Further, when it is determined that the current air volume has reached the maximum air volume value Afm, the set value calculation processing unit 256 sets the capability Qe of the device calculated by the operation frequency calculation unit 256e in the capability calculation unit 56c. The operating frequency set value is calculated in light of the value table. That is, the operating frequency calculation unit 256e determines that the evaporation temperature Te is equal to or lower than the freezing threshold T in the freezing determination unit 55, and the air volume blown to the evaporator 24 by the blower 31 reaches the maximum airflow value Afm. In this case, the operation frequency set value is calculated. The operation frequency calculation unit 256e has a function of outputting information on the calculated operation frequency set value to the operation control unit 257.

The operation control unit 257 has a function of adjusting the operation frequency of the compressor 21 based on the operation frequency set value calculated by the operation frequency calculation unit 256e. The operation control unit 257 performs compression when the freezing determination unit 55 determines that the evaporation temperature Te is equal to or lower than the freezing threshold T and the air volume blown to the evaporator 24 by the blower 31 has reached the maximum airflow value Afm. The operating frequency of the machine 21 is lowered. Other configurations of the operation control unit 257 are the same as those of the operation control unit 57 of the first embodiment described above.

FIG. 10 is an explanatory diagram illustrating the relationship between the evaporation temperature, the air volume, and the operating frequency of the compressor in the air conditioner of FIG. As shown in FIG. 10, the air conditioner 210 can increase the amount of air passing through the evaporator 24 in the air amount adjustment range R when the evaporation temperature Te decreases to the freezing threshold T. In addition, the air conditioner 210 operates the compressor 21 for the first time when the evaporation temperature Te decreases to the freezing threshold T when the air volume blown to the evaporator 24 by the blower 31 reaches the maximum air volume value Afm. Reduce the frequency. Therefore, according to the air conditioner 210, freezing of the evaporator 24 can be suppressed by suppressing a decrease in capacity as much as possible.

FIG. 11 is a flowchart showing an operation example during the cooling operation of the air conditioner 110 of FIG. With reference to FIG. 11, the freezing suppression control by the air conditioner 210 of this Embodiment 3 is demonstrated. The same steps as those shown in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted.

The air conditioner 210 performs the processing of steps S101 to S102 as in the case of FIG. When the freezing determination unit 55 determines that the evaporation temperature Te is equal to or lower than the freezing threshold T (Yes in step S102), the air volume determination unit 258 determines whether or not the current air volume has reached the maximum air volume value Afm. Determination is made (step S201).

When the air volume determination unit 258 determines that the current air volume is less than the maximum air volume value Afm (step S201 / No), the set value calculation processing unit 256 calculates the air volume setting value and calculates the calculated air volume setting value. The information is output to the operation control unit 257 (step S103), and the process proceeds to step S104. On the other hand, when it is determined by the air volume determination unit 258 that the current air volume has reached the maximum air volume value Afm (step S201 / Yes), the set value calculation processing unit 256 calculates and calculates the operating frequency set value. Information on the operating frequency set value is output to the operation control unit 257 (step S202).

The operation control unit 257 adjusts the operation frequency of the compressor 21 so that the operation frequency of the compressor 21 becomes the operation frequency setting value according to the information of the operation frequency setting value output from the set value calculation processing unit 56 ( Step S203). Next, the process proceeds to step S105, and when the set time has elapsed (step S105 / Yes), the process returns to step S101.

As described above, the air conditioner 210 according to the third embodiment preferentially performs the process of increasing the amount of air passing through the evaporator 24 when the evaporation temperature is equal to or lower than the freezing threshold T. Therefore, since the capacity | capacitance reduction of the compressor 21 can be suppressed to the minimum, the freezing of the evaporator 24 can be suppressed, suppressing the fall of the cooling capacity of the air conditioner 210. FIG. That is, the air conditioner 210 increases the rotational frequency of the blower 31 and, in the case where there is still a possibility of freezing, reduces the operating frequency of the compressor 21, thereby minimizing the decrease in capacity, Freezing of the evaporator 24 can be prevented with high accuracy.

By the way, in the above, the case where the set value calculation processing unit 256 calculates only the rotation frequency set value when it is determined that the current air volume is less than the maximum air volume value Afm is illustrated, but the present invention is not limited thereto. It is not something. FIG. 12 is an explanatory diagram illustrating another relationship among the evaporation temperature, the air volume, and the operating frequency of the compressor in the air conditioner of FIG. For example, when the difference between the current air volume and the maximum air volume value Afm is small as at time M shown in FIG. 12, it is possible to sufficiently prevent freezing even if the rotational frequency of the blower 31 is increased to the maximum air volume value Afm. There is no possibility. Therefore, assuming such a case, when the evaporation temperature Te decreases to the freezing threshold T, the set value calculation processing unit 256 increases the rotational frequency of the blower 31 and decreases the operating frequency of the compressor 21. May be.

In this case, for example, one setting value table in which the capability Qe of the device, the rotation frequency setting value, and the operation frequency setting value are associated is stored in the storage unit 51, and the control device 250 performs the function of the air volume calculation unit 56 d. It is preferable to have a calculation unit that combines the functions of the operation frequency calculation unit 256e. The set value calculation processing unit 256 calculates both the rotation frequency set value and the operation frequency set value regardless of the determination result by the air volume determination unit 258, and outputs the calculation result to the operation control unit 257. May be. In this way, even when the difference between the rotational frequency of the blower 31 and the maximum airflow value Afm at the time of determination by the air flow determination unit 258 is small and the amount of increase in the rotational frequency of the blower 31 is not sufficient, the operation of the compressor 21 is performed. By reducing the frequency, freezing of the evaporator 24 can be prevented with high accuracy.

In addition, the air conditioner 210 may include an air volume adjustment unit 130 instead of the air volume adjustment unit 30, and may include an air volume calculation unit 156d instead of the air volume calculation unit 56d. And the operation control part 257 may have the function to adjust the opening degree of the air volume adjustment damper 32 similarly to the operation control part 157. That is, the air conditioner 210 performs anti-freezing control of the evaporator 24 by combining the adjustment of the rotation frequency of the blower 31, the adjustment of the opening degree of the air volume adjustment damper 32, and the adjustment of the operation frequency of the compressor 21. You may do it. According to the air conditioner 210 adopting such a configuration, finer and more flexible freezing prevention control can be performed, so that the freezing of the evaporator 24 can be prevented with higher accuracy.

10 and 12 show a state in which the rotational frequency of the blower 31 is increased in a stepwise manner and then the operating frequency of the compressor 21 is lowered in a stepwise manner as the outside air temperature decreases with time. . However, the air conditioner 210 performs an increase process or a decrease process of the rotational frequency of the blower 31 and an increase process or a decrease process of the operating frequency of the compressor 21 in accordance with a change in the outside air temperature, that is, a change in the capacity Qe of the device. May be performed in combination.

Embodiment 4 FIG.
FIG. 13 is a schematic view illustrating the configuration of an air conditioner according to Embodiment 4 of the present invention. FIG. 14 is a block diagram illustrating a functional configuration of a control device included in the air conditioner of FIG. Based on FIG. 13 and FIG. 14, the structure and operation | movement of the air conditioner which concerns on this Embodiment 4 are demonstrated. Constituent members equivalent to those in the first to third embodiments described above are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 13, the air conditioner 310 according to the fourth embodiment includes a refrigerant circuit 310 </ b> A including a bypass circuit 320 that bypasses the refrigerant flowing into the evaporator 24. Other configurations of the refrigerant circuit 310A are the same as those of the refrigerant circuit 10A.

The bypass circuit 320 includes a bypass pipe 320a that connects the inlet side and the outlet side of the evaporator 24, and a flow rate adjustment valve 320b that is provided in the bypass pipe 320a and adjusts the flow rate of the refrigerant flowing into the bypass pipe 320a. is doing. The flow rate adjustment valve 320b is composed of, for example, an electronic expansion valve, and the opening degree can be adjusted.

Moreover, the air conditioner 310 has the control apparatus 350 which controls operation | movement of 130 A of refrigerant circuits and the air volume adjustment unit 30, as shown to FIG. 13 and FIG. The control device 350 includes a storage unit 51, a condensation temperature calculation unit 52, a supercooling degree calculation unit 53, a superheat degree calculation unit 54, a freezing determination unit 55, a set value calculation processing unit 356, and an operation control unit 357. And an air volume determination unit 258.

The storage unit 51 in the fourth embodiment stores a rotation frequency setting value as an air flow setting value and a valve opening setting value indicating the opening of the flow rate adjustment valve 320b. The rotational frequency set value and the valve opening set value are set in advance for preventing the evaporator 24 from freezing. More specifically, in the storage unit 51, as a setting value table, a rotation setting value table in which the device capability Qe and the rotation frequency setting value are associated, and a device capability Qe and the valve opening setting value are associated. A valve opening setting value table is stored. In the valve opening setting value table, the valve opening setting value is associated with each range of the capability Qe of the device. The valve opening setting value table is configured such that the valve opening setting value increases when the capability Qe of the device decreases.

The set value calculation processing unit 356 includes an evaporation pressure calculation unit 56a, a refrigerant flow rate calculation unit 56b, a capacity calculation unit 56c, an air volume calculation unit 56d, and a valve opening calculation unit 356f. In the set value calculation processing unit 356, when the air volume determination unit 258 determines that the current air volume is less than the maximum air volume value Afm, the air volume calculation unit 56d calculates the rotation frequency setting value.

Further, when it is determined that the current air volume has reached the maximum air volume value Afm, the set value calculation processing unit 356 controls the device performance Qe calculated by the capacity calculation unit 56c. The valve opening setting value is calculated in light of the opening setting value table. That is, the valve opening calculation unit 356f determines that the evaporation temperature Te is equal to or lower than the freezing threshold T in the freezing determination unit 55, and the air volume blown to the evaporator 24 by the blower 31 reaches the maximum airflow value Afm. In this case, the valve opening setting value is calculated. The valve opening calculation unit 356f has a function of outputting information of the calculated valve opening setting value to the operation control unit 357.

The operation control unit 357 has a function of adjusting the opening of the flow rate adjustment valve 320b based on the valve opening setting value calculated by the valve opening calculating unit 356f. That is, the operation control unit 357 has a function of bypassing a part of the refrigerant flowing into the evaporator 24 to the bypass circuit 320. The operation control unit 357 determines the flow rate when the freezing determination unit 55 determines that the evaporation temperature Te is equal to or lower than the freezing threshold T and the amount of air blown to the evaporator 24 by the blower 31 has reached the maximum airflow value Afm. The opening degree of the adjustment valve 320b is increased. Other configurations of the operation control unit 357 are the same as those of the operation control unit 57 of the first embodiment described above.

The operation of the air conditioner 310 is the same as the operation of the air conditioner 210 described with reference to FIG. That is, when the air volume determination unit 258 determines that the current air volume has reached the maximum air volume value Afm (step S201 / Yes), the set value calculation processing unit 356 calculates the valve opening set value, Information on the calculated valve opening setting value is output to the operation control unit 357 (corresponding to step S202). The operation control unit 357 opens the opening of the flow rate adjustment valve 320b according to the information on the valve opening setting value output from the set value calculation processing unit 56 so that the opening of the flow rate adjustment valve 320b becomes the valve opening setting value. (Corresponding to step S203).

Here, the flow rate adjustment valve 320b may be an electromagnetic valve or the like that can only be opened and closed. In this case, for example, the air conditioner 310 may keep the flow rate adjustment valve 320b closed in a state where the evaporator 24 is not likely to freeze. The air conditioner 310 opens the flow rate adjustment valve 320b when there is a possibility that the evaporator 24 may freeze and the rotation frequency of the blower 31 reaches the maximum airflow value Afm. You may make it do.

As described above, the air conditioner 310 according to the fourth embodiment preferentially performs the process of increasing the amount of air passing through the evaporator 24 when the evaporation temperature is equal to or lower than the freezing threshold T. Therefore, according to the air conditioner 310, since the reduction | decrease in the refrigerant | coolant inflow amount to the evaporator 24 can be suppressed to the minimum, the freezing of the evaporator 24 is suppressed, suppressing the fall of the cooling capacity of the air conditioner 310. can do.

By the way, in the above, the case where the set value calculation processing unit 256 calculates only the rotation frequency set value when it is determined that the current air volume is less than the maximum air volume value Afm is illustrated, but the present invention is not limited thereto. It is not something. For example, the set value calculation processing unit 356 may increase the rotational frequency of the blower 31 and increase the opening of the flow rate adjustment valve 320b when the evaporation temperature Te decreases to the freezing threshold T. In this case, for example, the storage unit 51 stores one set value table in which the capability Qe of the device, the rotation frequency set value, and the valve opening set value are associated, and the control device 350 stores the air volume calculation unit 56d. It is preferable to have a calculation unit that has both the function and the function of the valve opening calculation unit 356f. The set value calculation processing unit 356 calculates both the rotation frequency set value and the valve opening set value regardless of the determination result by the air volume determination unit 258, and outputs the calculation result to the operation control unit 357. It may be. In this way, the difference between the rotational frequency of the blower 31 and the maximum airflow value Afm at the time of determination by the air volume determination unit 258 is small, and even when the increase amount of the rotational frequency of the blower 31 is not sufficient, the flow rate adjustment valve 320b By increasing the opening, freezing of the evaporator 24 can be accurately prevented.

In addition, the air conditioner 310 may include an air volume adjusting unit 130 instead of the air volume adjusting unit 30, and may include an air volume calculating unit 156d instead of the air volume calculating unit 56d. And the operation control part 357 may have the function to adjust the opening degree of the air volume adjustment damper 32 similarly to the operation control part 157. That is, the air conditioner 310 performs antifreezing control of the evaporator 24 by combining the adjustment of the rotation frequency of the blower 31, the adjustment of the opening of the air volume adjustment damper 32, and the adjustment of the opening of the flow rate adjustment valve 320b. You may make it perform. In addition, the air conditioner 310 further includes an operation frequency calculation unit 256e, which combines the adjustment of the rotation frequency of the blower 31, the adjustment of the operation frequency of the compressor 21, and the adjustment of the opening degree of the flow rate adjustment valve 320b. Thus, the freeze prevention control of the evaporator 24 may be performed. However, the air conditioner 310 may include the operation frequency calculation unit 256e and may include the air volume adjustment unit 130 and the air volume calculation unit 156d instead of the air volume adjustment unit 30 and the air volume calculation unit 56d. The air conditioner 310 combines the adjustment of the rotational frequency of the blower 31, the adjustment of the opening of the air volume adjustment damper 32, the adjustment of the operating frequency of the compressor 21, and the adjustment of the opening of the flow rate adjustment valve 320b. Thus, the freeze prevention control of the evaporator 24 may be performed. According to the air conditioner 310 adopting each configuration as described above, since the freeze prevention control can be performed more finely and flexibly, the freezing of the evaporator 24 can be prevented with higher accuracy.

Here, a comparative example for explaining the effect obtained by the air conditioner of each of the above embodiments in more detail will be described with reference to FIG. FIG. 15 is an explanatory diagram showing the relationship among the evaporation temperature, the air volume, and the operating frequency of the compressor in a conventional air conditioner. In FIG. 15, for the sake of convenience, it is assumed that the freezing threshold T, the frequency lower limit value L, and the airflow initial value Afi are set in order to compare with the air conditioner in each of the above embodiments. As shown in FIG. 15, in the conventional air conditioner, when the evaporation temperature is lowered to the freezing threshold T, the operating frequency of the compressor is lowered, so that the capacity of the air conditioner is lowered and required for cooling operation. There is a problem that it becomes impossible to maintain the ability. Furthermore, as shown by “x” in FIG. 15, if the evaporation temperature falls below the freezing threshold T even if the operating frequency of the compressor is reduced to the lower frequency limit L, the evaporator should be prevented from freezing. Can not be.

In this respect, the air conditioner in each of the above embodiments increases the amount of air passing through the evaporator 24 when the evaporation temperature Te is lowered to the freezing threshold T, so that the evaporator 24 can be prevented from freezing. Furthermore, the air conditioner in the third and fourth embodiments has a function of adjusting at least one of the operating frequency of the compressor 21 and the opening degree of the flow rate adjusting valve 320b as well as the adjustment of the amount of air passing through the evaporator 24. Have. That is, according to the air conditioner in the third and fourth embodiments, the evaporator 24 is frozen by adjusting the air volume by at least one of adjusting the operating frequency of the compressor 21 and adjusting the opening of the flow rate adjusting valve 320b. Since the prevention process can be compensated, the accuracy of the freeze prevention can be improved.

The above embodiments are preferred specific examples of the air conditioner, and the technical scope of the present invention is not limited to these embodiments. For example, in each of the above embodiments, an air conditioner that performs a cooling operation is illustrated, but the present invention is not limited to this. The air conditioner in each embodiment may be configured such that a four-way valve for switching the refrigerant flow path is provided in the refrigerant circuit so that switching between the cooling operation and the heating operation is possible. In addition, when an air conditioner performs heating operation, the condenser 22 functions as an evaporator, and the evaporator 24 functions as a condenser.

In addition, the air conditioner in each of the above embodiments is not limited to the configuration using the above-described components. That is, the air conditioner in each embodiment may include an accumulator that separates the liquid refrigerant in order to protect the compressor 21, or an oil separator to recover the refrigeration oil. Also good. The refrigerant used in the air conditioner in each of the above embodiments may be any refrigerant that can use the refrigeration cycle. For example, a single refrigerant such as R22 or a mixed refrigerant such as R410A may be used. Natural refrigerants such as CO2 may also be used.

10, 110, 210, 310 Air conditioner, 10A, 310A refrigerant circuit, 20 refrigerant piping, 21 compressor, 22 condenser, 23 decompressor, 24 evaporator, 30, 130 air volume adjustment unit, 31 blower, 31a fan motor , 31b fan, 32 air volume adjustment damper, 41 condenser pressure sensor, 42 condenser outlet temperature sensor, 43 evaporator inlet temperature sensor, 44 evaporator outlet temperature sensor, 50, 150, 250, 350 control device, 51 storage unit, 52 Condensation temperature calculation unit, 53 Supercooling degree calculation unit, 54 Superheat degree calculation unit, 55 Freezing determination unit, 56, 156, 256, 356 Set value calculation processing unit, 56a Evaporation pressure calculation unit, 56b Refrigerant flow rate calculation unit, 56c Ability calculation unit, 56d, 156d, air volume calculation unit, 57, 157, 257, 3 7 Operation control unit, 256e Operation frequency calculation unit, 258 Air flow determination unit, 320 Bypass circuit, 320a bypass piping, 320b Flow adjustment valve, 356f Valve opening calculation unit, Afi air flow initial value, Afm air flow maximum value, Gr refrigerant flow rate, Pcm condensing pressure, Pe evaporating pressure, Qe equipment capacity, T freezing threshold, Te evaporating temperature, hr evaporator inlet enthalpy, hro evaporator outlet enthalpy, Δhr evaporator inlet / outlet enthalpy difference, V compressor displacement, ρ compressed Density of refrigerant.

Claims

A refrigerant circuit formed by connecting a compressor that compresses the refrigerant, a condenser that condenses the refrigerant, a decompression device that decompresses the refrigerant, and an evaporator that evaporates the refrigerant through a refrigerant pipe;
An air volume adjusting unit that adjusts an air volume that passes through the evaporator, and has a blower that blows air to the evaporator;
A control device for controlling the operation of the refrigerant circuit and the air volume adjustment unit;
With
The control device includes:
A freezing determination unit for determining whether or not the evaporation temperature is equal to or lower than a freezing threshold;
When the freezing determination unit determines that the evaporation temperature is equal to or lower than the freezing threshold, the air volume setting value indicating the air volume blown to the evaporator by the air volume adjusting unit is calculated based on the operating frequency of the compressor. A set value calculation processing unit to
An air conditioner comprising: an operation control unit configured to increase an air volume passing through the evaporator based on the air volume setting value calculated in the set value calculation processing unit.
The operation controller is
2. The air conditioner according to claim 1, wherein a rotational frequency of the blower is increased to increase an amount of air passing through the evaporator.
The air volume adjusting unit is
An air volume adjusting damper attached to the evaporator, for adjusting an air volume passing through the evaporator;
The operation controller is
The air conditioner according to claim 1 or 2, wherein the air volume adjusting damper is opened to increase an air volume passing through the evaporator.
The set value calculation processing unit
The operation frequency indicating the operation frequency of the compressor when the evaporating temperature is determined to be equal to or lower than the freezing threshold in the freezing determination unit and the amount of air blown to the evaporator by the blower has reached the maximum value. It has an operation frequency calculation part that calculates the set value,
The operation controller is
The air conditioner according to any one of claims 1 to 3, wherein the air conditioner has a function of lowering an operation frequency of the compressor based on the operation frequency set value calculated by the operation frequency calculation unit.
The refrigerant circuit is
A bypass pipe connecting the inlet side and the outlet side of the evaporator;
A flow rate adjusting valve that is provided in the bypass pipe and adjusts the flow rate of the refrigerant flowing into the bypass pipe;
The set value calculation processing unit
A valve that indicates the opening degree of the flow rate adjustment valve when the freezing determination unit determines that the evaporation temperature is equal to or lower than the freezing threshold and the amount of air blown to the evaporator by the blower reaches a maximum value. It has a valve opening calculation unit that calculates the opening setting value,
The operation controller is
The air conditioner according to any one of claims 1 to 4, wherein the air conditioner has a function of increasing an opening of the flow rate adjustment valve based on the valve opening setting value calculated by the valve opening calculation unit. .