WO2018163346A1

WO2018163346A1 - Air conditioner

Info

Publication number: WO2018163346A1
Application number: PCT/JP2017/009419
Authority: WO
Inventors: 孝史福井
Original assignee: 三菱電機株式会社
Priority date: 2017-03-09
Filing date: 2017-03-09
Publication date: 2018-09-13
Also published as: JPWO2018163346A1; JP6779361B2

Abstract

An air conditioner comprises: an operating state detection means that detects the operating state of the air conditioner; a refrigerant flow assessment means that estimates the refrigerant flow circulating through a refrigerant circuit on the basis of the operating state detected by the operating state detection means and assesses whether operation is proceeding at a high refrigerant flow; and a control means that, in the event of the refrigerant flow assessment means assessing that operation is proceeding at a refrigerant flow exceeding a predetermined amount, performs a control so as to reduce the maximum operating frequency of a compressor until a predetermined time period has passed after the compressor has started.

Description

Air conditioner

The present invention relates to an air conditioner having a refrigerant circuit for circulating a refrigerant.

Conventionally, a compressor, a condenser, a throttle unit mechanism and an evaporator that compress refrigerant and are lubricated by refrigeration oil have been provided, and refrigeration oil and refrigerant are placed above the compressor discharge part between the compressor and the condenser. There has been proposed a refrigeration cycle in which an oil separator to be separated and stored is installed and an oil return pipe is connected from the bottom of the oil separator to the compressor suction portion via an on-off valve (for example, Patent Documents 1 and 2). reference).

Also, as a prior art, there is provided a control means that can vary the time for which the compressor can be held at a constant frequency for a predetermined time according to the length of the installation pipe after the compressor is started, and lubrication discharged from the compressor. There has been proposed an air conditioner that operates to increase the operating frequency of the compressor after the oil returns to the compressor through the refrigeration cycle (see, for example, Patent Document 3).

In addition, as a conventional technique, the operation mode of cooling or heating is judged, and the rising speed of the starting frequency is set differently by comparing the outdoor temperature with the reference temperature, and the compressor is set according to the set starting frequency rising speed. There has been proposed a compressor activation control method for an air conditioner in which a compressor is operated by changing its frequency to a target frequency after activation (see, for example, Patent Document 4).

JP 2009-103449 A JP 2001-201191 A Japanese Unexamined Patent Publication No. 1-6653 JP-A-6-101925

However, in the prior arts of Patent Document 1 and Patent Document 2, the refrigeration oil flowing out from the compressor together with the refrigerant can be returned to the compressor with high accuracy, so that the oil return is improved. Since an oil separator that separates the refrigerant circulating in the circuit and the refrigerating machine oil is required, a space for installing this device in the predetermined refrigerant circuit is required, resulting in an increase in the size of the product body, and the cost of the product There was a problem to be up.
In addition, from the aspect of the refrigerant flow in the refrigeration cycle, since the refrigerant flow is suppressed and resistance is generated, there is a problem of performance loss.

Moreover, in the prior art of patent document 3, although the oil return property of the refrigerating machine oil to a compressor can be ensured corresponding to the difference in equipment installation conditions like installation pipe length, the change of a refrigerating cycle operation state There was a problem that could not cope with.

Further, in the prior art of Patent Document 4, it is possible to ensure oil repellency corresponding to differences in operation modes of cooling and heating, and changes in outside air temperature and indoor set temperature. There was a problem that the oil-repellent property corresponding to could not be secured.

The present invention has been made in order to solve the above-described problems, and does not require an additional element that causes an increase in cost such as an oil separator, and the length of the refrigerant pipe that connects the outdoor unit and the indoor unit. Regardless of the installation conditions, operating conditions, and operating conditions of the air conditioning equipment such as the height of the unit installation location and the refrigerant charge amount, ensuring the oil-repellent property to maintain a certain amount of refrigeration oil in the compressor, and improving the reliability of the air conditioning equipment It aims at obtaining the air conditioning apparatus which implement | achieves performance improvement by avoiding the refrigerating cycle performance fall accompanying refrigerating machine oil storing in the element in a refrigerant circuit while ensuring.

The air conditioner according to the present invention is
At least one room having a compressor, a four-way valve, an outdoor heat exchanger, an outdoor air blower, an outdoor air blower, an opening degree variable pressure reducing device, an indoor heat exchanger, and an indoor air blower, each of which has a variable driving frequency. Air conditioning operation of the air conditioner in the air conditioner in which the unit is connected by a refrigerant pipe and the refrigerant circuit for circulating the refrigerant to the compressor, four-way valve, outdoor heat exchanger, decompression device, and indoor heat exchanger is configured. A control device that controls the operation state detecting means for detecting the operation state, and the flow rate of refrigerant circulating in the refrigerant circuit based on the operation state detected by the operation state detection means, and based on a preset threshold value The refrigerant flow rate determining means for determining whether or not the operating condition has a high refrigerant flow rate, and the maximum operation of the compressor when the refrigerant flow rate determining means determines that the operating condition has a refrigerant flow rate greater than a predetermined amount And control means for controlling so as to lower the frequency, but with a.

The air conditioner of the present invention estimates the refrigerant flow rate circulating through the refrigerant circuit based on the operating condition detecting means for detecting the operating condition of the air conditioner and the operating condition detected by the operating condition detecting means. The refrigerant flow rate determining means for determining whether or not there are many operating conditions, and when the refrigerant flow rate determining means determines that the refrigerant flow rate is higher than a predetermined amount, the compressor flow rate Control means to control the maximum operating frequency to be low, so no additional elements such as oil separators that increase costs are required, and a certain amount or more in the compressor regardless of operating conditions and operating conditions Since it is possible to ensure the oil-repellent property of maintaining the refrigerating machine oil, it is possible to realize a highly reliable air conditioner.

It is a refrigerant circuit block diagram of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the electrical structure of the control apparatus of the air conditioning apparatus which concerns on Embodiment 1 of this invention. FIG. 3 is a Ph diagram illustrating a state transition of a refrigerant in the air-conditioning apparatus according to Embodiment 1 of the present invention. It is a flowchart which shows the control action of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the control action of the air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows the control action of the air conditioning apparatus which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
"Equipment configuration"
The present invention will be described below with reference to illustrated embodiments.
FIG. 1 is a refrigerant circuit diagram schematically showing an air-conditioning apparatus 100 according to Embodiment 1 of the present invention.
The air conditioner 100 is an apparatus used for indoor air conditioning by performing a vapor compression refrigeration cycle operation. The air conditioner 100 includes a heat source unit A, a liquid connection pipe 6 and a gas connection pipe 9 serving as a refrigerant communication pipe. And a plurality of use units B (one in the present embodiment) connected in parallel.

Examples of the refrigerant used in the air conditioner include HFC refrigerants such as R410A, R407C, R404A, and R32, HFO refrigerants such as R1234yf / ze, HCFC refrigerants such as R22 and R134a, carbon dioxide (CO ₂ ), and carbonized carbon. There are natural refrigerants such as hydrogen, helium and propane.

<Usage unit>
The use unit B is installed in the indoor ceiling by embedding or hanging, or wall-mounted on the indoor wall surface, and is connected to the heat source unit A via the liquid connection pipe 6 and the gas connection pipe 9 as described above. It constitutes a part of the refrigerant circuit.

Next, the detailed configuration of the usage unit B will be described. The usage unit B constitutes an indoor side refrigerant circuit that is a part of the refrigerant circuit, and includes an indoor air blower 8 and an indoor heat exchanger 7 that is a usage side heat exchanger.

Here, the indoor heat exchanger 7 is composed of a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and functions as a refrigerant evaporator during cooling operation. In the heating operation, it functions as a refrigerant condenser and heats indoor air.

The indoor air blower 8 is a fan capable of changing the flow rate of air supplied to the indoor heat exchanger 7, and is composed of, for example, a centrifugal fan or a multiblade fan driven by a DC motor (not shown). Thus, indoor air is sucked into the use unit B, and the air heat exchanged with the refrigerant by the indoor heat exchanger 7 is supplied to the room as supply air.

In addition, various sensors are installed in the use unit B. That is, on the liquid side of the indoor heat exchanger 7, the temperature of the refrigerant in the liquid state or the gas-liquid two-phase state (the supercooled liquid temperature Tco during the heating operation or the refrigerant temperature corresponding to the evaporation temperature Te during the cooling operation). A liquid side temperature sensor 205 for detection is provided. The indoor heat exchanger 7 has a gas-side temperature sensor 207 that detects the temperature of the refrigerant in the gas-liquid two-phase state (condensation temperature Tc during heating operation or refrigerant temperature corresponding to the evaporation temperature Te during cooling operation). Is provided. Further, an indoor temperature sensor 206 for detecting the temperature of the indoor air flowing into the unit is provided on the indoor air inlet side of the utilization unit B. Here, all of the liquid side temperature sensor 205, the gas side temperature sensor 207, and the room temperature sensor 206 are composed of thermistors. Operation | movement of the indoor air blower 8 is controlled by the operation control means (control part 30).

<Heat source unit>
The heat source unit A is installed outdoors and is connected to the utilization unit B through the liquid connection pipe 6 and the gas connection pipe 9 and constitutes a part of the refrigerant circuit.

Next, the detailed configuration of the heat source unit A will be described. The heat source unit A includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3 as a heat source side heat exchanger, an outdoor air blower 4, a decompressor 5a, a decompressor 5b, and a receiver 11. ing.

The

decompression devices

5a and 5b are connected to the liquid side of the heat source unit A in order to adjust the flow rate of the refrigerant flowing in the refrigerant circuit.

The compressor 1 is a compressor capable of varying the operating capacity (frequency), and here, a positive displacement compressor driven by a motor (not shown) controlled by an inverter is used. In addition, although the compressor 1 is only one here, it is not limited to this, According to the number of use units etc., two or more compressors may be connected in parallel. .

The four-way valve 2 is a valve having a function of switching the direction of refrigerant flow. During the cooling operation, compression is performed so that the outdoor heat exchanger 3 functions as a refrigerant condenser compressed in the compressor 1 and the indoor heat exchanger 7 functions as a refrigerant evaporator condensed in the outdoor heat exchanger 3. The discharge side of the machine 1 and the gas side of the outdoor heat exchanger 3 are connected, and the refrigerant flow path is switched so as to connect the suction side of the compressor 1 and the gas connection pipe 9 side (four-way valve 2 in FIG. 1). Dashed line). During the heating operation, compression is performed so that the indoor heat exchanger 7 functions as a refrigerant condenser compressed in the compressor 1 and the outdoor heat exchanger 3 functions as a refrigerant evaporator condensed in the indoor heat exchanger 7. 1 is connected to the discharge side of the compressor 1 and the gas connection pipe 9 side, and the refrigerant flow path is switched to connect the suction side of the compressor 1 and the gas side of the outdoor heat exchanger 3 (four-way valve 2 in FIG. 1). Solid line).

The outdoor heat exchanger 3 is a cross-fin type fin-and-tube type composed of a heat transfer tube whose gas side is connected to the four-way valve 2 and whose liquid side is connected to the liquid connection pipe 6 and a large number of fins. It consists of a heat exchanger and functions as a refrigerant condenser during cooling operation and as a refrigerant evaporator during heating operation.

The outdoor blower 4 is a fan capable of changing the flow rate of air supplied to the outdoor heat exchanger 3, and is composed of, for example, a propeller fan driven by a DC motor (not shown). Accordingly, the outdoor air is sucked into the heat source unit A, and the air heat-exchanged with the refrigerant by the outdoor heat exchanger 3 is discharged to the outside.

The receiver 11 is a refrigerant container that stores liquid refrigerant. The receiver 11 stores liquid refrigerant that has become excessive during operation and has a gas-liquid separation function. The internal heat exchanger 12 is built in the receiver 11 and heats the refrigerant circulating in the gas connection pipe 9 that connects the four-way valve 2 and the suction portion of the compressor 1 and the liquid refrigerant stored in the receiver 11. Refrigerant piping is connected and configured to be replaced.

In addition, various sensors are installed in the heat source unit A. That is, the compressor 1 is provided with a discharge temperature sensor 201 for detecting the discharge temperature Td, and the outdoor heat exchanger 3 has a gas-liquid two-phase refrigerant temperature (condensation temperature Tc during cooling operation or A gas side temperature sensor 202 for detecting a refrigerant temperature corresponding to the evaporation temperature Te during heating operation is provided. Further, on the liquid side of the outdoor heat exchanger 3, a liquid side temperature sensor 204 for detecting the temperature of the refrigerant in the liquid state or the gas-liquid two-phase state is provided. An outdoor temperature sensor 203 for detecting the temperature of the outdoor air flowing into the unit, that is, the outdoor air temperature Ta, is provided on the outdoor air inlet side of the heat source unit A. Here, the discharge temperature sensor 201, the gas side temperature sensor 202, the outdoor temperature sensor 203, and the liquid side temperature sensor 204 are all composed of a thermistor. In addition, operation | movement of the compressor 1, the four-way valve 2, the outdoor air blower 4, and the

pressure reduction apparatus

5a, 5b is controlled by the operation control means (control part 30).

As described above, the heat source unit A and the utilization unit B are connected via the liquid connection pipe 6 and the gas connection pipe 9 to constitute the refrigerant circuit of the air conditioner. In the present embodiment, the liquid connection pipe 6 and the gas connection pipe 9 are constituted by long (for example, a total length of 100 m or more) refrigerant pipe. The longer the refrigerant pipe length, the greater the required amount of refrigerant and the greater the amount of oil discharged from the compressor. Therefore, the oil return until the discharged refrigeration oil returns to the compressor also deteriorates. For this reason, it has an effect that the reliability can be maintained under conditions exceeding the total length of 100 m currently permitted as installation conditions.

Here, when the length of the refrigerant pipe connecting the heat source unit A and the utilization unit B becomes long, the refrigerant of the air conditioner according to the length in order to perform an appropriate refrigeration cycle operation in the refrigerant circuit It is necessary to increase the filling amount. The refrigerant flow rate circulating in the refrigerant circuit is relatively increased according to the refrigerant charge amount.

As a general compressor characteristic, refrigeration oil filled for lubrication in the compressor is easily discharged into the refrigerant circuit together with the refrigerant due to an increase in the refrigerant flow rate. That is, the oil circulation rate of the refrigerating machine oil, which is defined by the ratio of the mass flow rate of the refrigerating machine oil to the total mass flow rate of the refrigerant and the refrigerating machine oil, is increased.

In the present embodiment, the configuration in the case where there is one heat source unit A will be described as an example. However, the present invention is not limited to this, and there may be a plurality of heat source units A that are two or more. good. Further, in the case where both the heat source unit A and the utilization unit B are a plurality of units, the respective capacities may vary from large to small, or all may have the same capacity.

In the present embodiment, the configuration in which the heat source unit A and the utilization unit B are installed at the same height (the height difference is 0 m) will be described as an example. However, the present invention is not limited to this, and the heat source You may be comprised by the installation conditions (for example, 30 m or more of height differences) with a large height difference of the installation place height of the unit A and the utilization unit B. FIG.

In general, the greater the difference in height of the unit installation location, the more the refrigeration oil in the compressor mounted on the heat source unit A is discharged together with the refrigerant into the refrigerant circuit, and the effect of the head difference as hydrodynamic energy. In response to this, the refrigeration oil circulates through the refrigerant circuit and becomes difficult to return to the compressor, so that the oil return property is deteriorated. For this reason, the height difference of 30 m currently accepted as the installation height condition is used as a guide, and the reliability can be maintained even under conditions exceeding this.

FIG. 2 is a control block diagram according to Embodiment 1 of the present invention.
FIG. 2 shows a connection configuration of the control unit 30 that performs measurement control of the air-conditioning apparatus 100 of the first embodiment, operation information connected thereto, and actuators.

The control unit 30 is built in the air conditioner 100, and includes a measurement unit 30a, a calculation unit 30b, a drive unit 30c, a storage unit 30d, and a determination unit 30e.

Operation information detected by various sensors or the like is input to the measurement unit 30a, and operation state quantities such as pressure, temperature, and frequency are measured. The operation state quantity measured by the measurement unit 30a is input to the calculation unit 30b.

The calculation unit 30b calculates, for example, a refrigerant physical property value (saturation pressure, saturation temperature, density, etc.) using a formula given in advance based on the operation state quantity measured by the measurement unit 30a. Moreover, the calculating part 30b performs a calculation process based on the driving | running state amount measured by the measurement part 30a.

The driving unit 30c drives a compressor, a decompression device, a blower, and the like based on the calculation result of the calculation unit 30b.

The storage unit 30d is a function formula or function for calculating the results obtained by the calculation unit 30b, predetermined constants, specification values of the device and its constituent elements, and physical property values (saturation pressure, saturation temperature, density, etc.) of the refrigerant. A table (table) or the like is stored. These stored contents in the storage unit 30d can be referred to and rewritten as necessary. The storage unit 30d further stores a control program, and the control unit 30 controls the air conditioner 100 according to the program in the storage unit 30d.

The determination unit 30e performs processing such as large / small comparison and determination based on the result obtained by the calculation unit 30b.

The measurement unit 30a, the calculation unit 30b, the drive unit 30c, and the determination unit 30e are configured by, for example, a microcomputer, and the storage unit 30d is configured by a semiconductor memory or the like.

In the configuration example of the present embodiment, the control unit 30 is built in the air conditioner, but the present invention is not limited to this. The main control unit is provided in the heat source unit A, and the sub-control unit having a part of the function of the control unit is provided in the use unit B, and data communication is performed between the main control unit and the sub-control unit to perform the cooperation processing. A configuration, a configuration in which a control unit having all functions is installed in the use unit B, or a configuration in which the control unit is separately provided outside these units may be employed.

<Basic operation of air conditioner>
Subsequently, operations in each operation mode of the air-conditioning apparatus 100 according to Embodiment 1 will be described. First, the cooling operation will be described with reference to FIGS. 1 and 3.

During the cooling operation, the four-way valve 2 is in a state indicated by a broken line in FIG. 1, that is, the discharge side of the compressor 1 is connected to the gas side of the outdoor heat exchanger 3, and the suction side of the compressor 1 is the indoor heat exchanger 7. It is connected to the gas side.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 reaches the outdoor heat exchanger 3 that is a condenser via the four-way valve 2, and the refrigerant is condensed and liquefied by the blowing action of the outdoor air blower 4, and the high-pressure and low-temperature refrigerant. It becomes. The condensed and liquefied high-temperature and low-pressure refrigerant is decompressed by the decompression device 5 a to become a medium-pressure two-phase refrigerant, further decompressed by the decompression device 5 b via the receiver 11, and supplied to the usage unit B via the liquid connection pipe 6. Sent to the indoor heat exchanger 7. The decompressed two-phase refrigerant evaporates by the blowing action of the indoor blower 8 in the indoor heat exchanger 7 that is an evaporator, and becomes a low-pressure gas refrigerant. The low-pressure gas refrigerant exchanges heat with the medium-pressure two-phase refrigerant between the

decompression devices

5a and 5b in the internal heat exchanger 12 via the four-way valve 2, and then is sucked into the compressor 1 again.

In the internal heat exchanger 12 provided in the receiver 11, the high-temperature medium-pressure two-phase refrigerant decompressed by the decompression device 5a is saturated with the low-temperature low-pressure refrigerant circulating between the four-way valve 2 and the compressor 1 suction side. Cooled to the refrigerant (change from point D to point E in FIG. 3). At the same time, the low-pressure refrigerant is heated to become a low-pressure superheated gas refrigerant and flows into the compressor 1 (change from point G to point A in FIG. 3). Due to the heat exchange action in the internal heat exchanger 12, the enthalpy of the refrigerant flowing into the indoor heat exchanger 7 is reduced, and the enthalpy difference at the entrance and exit of the indoor heat exchanger 7 is increased. As a result, the refrigerant circulation amount necessary for obtaining the predetermined capacity is reduced, and the pressure loss is reduced, thereby improving the operation efficiency COP of the refrigeration cycle. At the same time, since the low-pressure refrigerant flowing into the compressor 1 is in a superheated gas state, a liquid back state due to an excessive inflow of liquid refrigerant into the compressor 1 is avoided.

Here, since the decompression device 5a controls the flow rate of the refrigerant by adjusting the opening degree so that the refrigerant subcooling degree at the outlet of the outdoor heat exchanger 3 becomes a predetermined value, it is condensed in the outdoor heat exchanger 3. The liquid refrigerant is in a state having a predetermined degree of supercooling. The refrigerant subcooling degree at the outlet of the outdoor heat exchanger 3 is detected by a value obtained by subtracting the gas side temperature sensor 202 (equivalent to the refrigerant condensation temperature Tc) from the detection value of the liquid side temperature sensor 204.

Further, since the decompression device 5b controls the flow rate of the refrigerant circulating through the indoor heat exchanger 7 by adjusting the opening degree so that the discharge refrigerant temperature of the compressor 1 becomes a predetermined value, the pressure reduction apparatus 5b is discharged from the compressor 1. The discharged gas refrigerant is in a predetermined temperature state. The discharge refrigerant temperature of the compressor 1 is detected by the compressor discharge temperature sensor 201 or the compressor shell temperature sensor 208. Thus, the refrigerant | coolant of the flow volume according to the driving | running load requested | required in the air-conditioning space in which the utilization unit B was installed flows into the indoor heat exchanger 7. FIG.

Next, the heating operation will be described with reference to FIGS. 1 and 3.

During the heating operation, the four-way valve 2 is in the state indicated by the solid line in FIG. 1, that is, the discharge side of the compressor 1 is connected to the gas side of the indoor heat exchanger 7 and the suction side of the compressor 1 is connected to the outdoor heat exchanger 3. It is connected to the gas side.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is sent to the utilization unit B via the four-way valve 2 and the gas connection pipe 9, reaches the indoor heat exchanger 7 that is a condenser, and is blown by the indoor blower 8. By the action, the refrigerant condenses and becomes a high-pressure and low-temperature refrigerant. The condensed and liquefied high-temperature and low-pressure refrigerant is sent to the heat source unit A via the liquid connection pipe 6 and is depressurized by the decompression device 5b to become an intermediate-pressure two-phase refrigerant, passes through the receiver 11, and is decompressed by the decompression device 5a. The pressure is further reduced and sent to the outdoor heat exchanger 3. The decompressed two-phase refrigerant is evaporated by the blowing action of the outdoor blower 4 in the outdoor heat exchanger 3 that is an evaporator, and becomes a low-pressure gas refrigerant. The low-pressure gas refrigerant exchanges heat with the medium-pressure two-phase refrigerant between the

decompression devices

In the internal heat exchanger 12, the high-temperature medium-pressure two-phase refrigerant decompressed by the decompression device 5b is cooled to the saturated liquid refrigerant by the low-temperature low-pressure refrigerant circulating between the four-way valve 2 and the compressor 1 suction side (see FIG. 3 point D → change of point E). At the same time, the low-pressure refrigerant is heated to become a low-pressure superheated gas refrigerant and flows into the compressor 1 (change from point G to point A in FIG. 3). Due to the heat exchange action in the internal heat exchanger 12, the enthalpy of the refrigerant flowing into the indoor heat exchanger 7 is reduced, and the enthalpy difference at the entrance and exit of the indoor heat exchanger 7 is increased. Thereby, the refrigerant circulation amount necessary for obtaining a predetermined capacity is reduced, and the COP of the refrigeration cycle is improved by reducing the pressure loss. At the same time, since the low-pressure refrigerant flowing into the compressor 1 is in a superheated gas state, a liquid back state due to an excessive inflow of liquid refrigerant into the compressor 1 is avoided.

Here, since the decompression device 5b controls the flow rate of the refrigerant flowing through the indoor heat exchanger 7 by adjusting the opening degree so that the degree of refrigerant supercooling at the outlet of the indoor heat exchanger 7 becomes a predetermined value, The liquid refrigerant condensed in the heat exchanger 7 is in a state having a predetermined degree of supercooling. The refrigerant subcooling degree at the outlet of the indoor heat exchanger 7 is detected by a value obtained by subtracting the gas side temperature sensor 207 (equivalent to the refrigerant condensation temperature Tc) from the detection value of the liquid side temperature sensor 205.

Further, since the decompression device 5a controls the flow rate of the refrigerant circulating in the outdoor heat exchanger 3 by adjusting the opening degree so that the discharge refrigerant temperature of the compressor 1 becomes a predetermined value, it is discharged from the compressor 1. The discharged gas refrigerant is in a predetermined temperature state. The discharge refrigerant temperature of the compressor 1 is detected by the compressor discharge temperature sensor 201 or the compressor shell temperature sensor 208. Thus, the refrigerant | coolant of the flow volume according to the driving | running load requested | required in the air-conditioning space in which the utilization unit B was installed flows into the indoor heat exchanger 7. FIG.

Although the detection value of the temperature sensor installed in each heat exchanger is used here as the refrigerant condensation temperature, a pressure sensor is installed on the discharge side of the compressor 1 to detect the refrigerant discharge pressure, and the discharge pressure The detected value may be converted into the saturation temperature and used as the refrigerant condensing temperature.

<< Start-up control method of air conditioner >>
A control operation at start-up in the air-conditioning apparatus 100 according to Embodiment 1 will be described with reference to FIG. FIG. 4 is a flowchart showing a flow of activation control of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

After starting the flow, the drive unit 30c starts the compressor 1, and the measurement unit 30a starts time t measurement (STEP 11). At this time, the control value of the maximum operating frequency Fmax of the compressor 1 is set to the initial value Fmax0.

Next, the operating state of the air conditioner 100 is detected by the measuring unit 30a (STEP 12). As an operation state detection means, for example, a temperature sensor that is installed in the heat source unit A or the utilization unit B of the air conditioner 100 and measures the refrigerant temperature and the air temperature, and a sensor that detects the operation frequency of the compressor 1 (not shown). Z). Based on these sensor detection values, it is detected as an operating state quantity.

Subsequently, the refrigerant flow rate Gr circulating through the refrigerant circuit of the air conditioner 100 is detected by calculating the refrigerant flow rate Gr by the calculation unit 30b based on the detected operating state quantity (STEP 13). Here, the refrigerant flow rate Gr is calculated using, for example, the following equation.

(1)

Here, Vst is the compressor stroke volume [m ³ ], F is the compressor operating frequency [Hz], ρs is the compressor suction refrigerant density [kg / m ³ ], and ηv is the volumetric efficiency [−]. . As the operating frequency F of the compressor, the operating state quantity detected by the measuring unit 30a is used. The compressor stroke volume Vst is a specification value of the compressor that is a component of the refrigerant circuit, is stored in advance in the storage unit 30d as device information, and is used as calculation information (constant) when calculating by the calculation unit 30b.

The compressor suction refrigerant density ρs is a refrigerant physical property value, and is a value corresponding to the operation state based on the information on the refrigerant physical property value stored in advance in the storage unit 30d and the operation state amount detected by the measurement unit 30a. Is used as calculation information when the calculation unit 30b calculates. The amount of operating state required at this time can be obtained from the intake refrigerant pressure Ps and the intake refrigerant temperature Ts of the compressor. As a method for detecting the suction refrigerant pressure Ps, for example, first, the refrigerant evaporating temperature Te is detected, and the detected pressure value is obtained by converting to a saturated pressure. The refrigerant evaporating temperature Te is a detection value of the gas side temperature sensor 207 provided in the indoor heat exchanger 7 (during cooling operation) or a detection value of the gas side temperature sensor 202 provided in the outdoor heat exchanger 3 (heating operation). Time).

The suction refrigerant temperature Ts is a low pressure Ps (equivalent to the suction pressure of the compressor) obtained by converting the evaporation temperature Te of the refrigerant into a saturation pressure, and a high pressure Pd (equivalent to the discharge pressure of the compressor) obtained by converting the condensation temperature Tc of the refrigerant into a saturation pressure. And the refrigerant discharge temperature Td, the compression step of the compressor 1 can be calculated from the following equation assuming that the polytropic index n is a polytropic change.

(1)

Here, Ts and Td are temperature [K], Ps and Pd are pressure [MPa], and n is a polytropic index [-]. The polytropic index may be a constant value (for example, n = 1.2), but by defining it as a function of Ps and Pd, the compressor intake refrigerant temperature Ts can be estimated more accurately.

Here, the high pressure and low pressure of the refrigerant are calculated from the condensation temperature and the evaporation temperature of the refrigerant. However, the pressure sensors are directly installed on the suction side and the discharge side of the compressor 1 to obtain the pressure. It may be. Of course, a temperature sensor may be installed on the suction side of the compressor 1 to directly detect the suction refrigerant temperature Ts.

The volumetric efficiency ηv is calculated when the calculation unit 30b calculates a value corresponding to the operation state based on the performance characteristics of the compressor previously stored in the storage unit 30d and the operation state quantity detected by the measurement unit 30a. Used as calculation information. Since the volumetric efficiency ηv mainly changes depending on the compressor frequency F and the compression ratio (ratio of the high pressure Pd and the low pressure Ps), the volumetric efficiency value corresponding to these state quantities is stored in the storage unit 30d. .

Subsequently, in the determination unit 30e, it is determined whether or not the refrigerant flow rate Gr detected by the calculation unit 30b is equal to or greater than a predetermined determination threshold value (predetermined value Gr0) for the refrigerant flow rate Gr (STEP 14). If the detected refrigerant flow rate Gr is equal to or greater than the predetermined value Gr0, it is determined that the refrigerant flow rate is high (STEP 14; YES), and the control value of the maximum operating frequency Fmax of the compressor 1 is lower than the current value by the drive unit 30c. Change to Fmax1 (STEP 15). If the conditions are not satisfied, it is determined that the refrigerant flow rate is not high (STEP 14; NO), and the drive unit 30c continues the operation while maintaining the current maximum operating frequency Fmax of the compressor 1 (STEP 16).

Here, the determination threshold value (predetermined value Gr0) of the refrigerant flow rate Gr and the maximum operating frequency Fmax are set to a level at which the refrigerating machine oil is not excessively discharged from the compressor 1 into the refrigerant circuit with respect to the refrigerant flow rate Gr. Set to. For example, the determination threshold Gr0 defined by the ratio of the mass flow rate of the refrigerating machine oil to the total mass flow rate of the refrigerant and the refrigerating machine oil so that the oil circulation rate of the refrigerating machine oil is 1.5% or less, and the maximum operating frequency Set Fmax.

Next, in order to determine whether or not the start control of the air conditioner 100 is to be terminated, it is determined in the determination unit 30e whether or not the predetermined time t0 has elapsed after the start of the compressor 1 (STEP 17). If the predetermined time t0 has not elapsed (STEP 17; NO), the process returns to STEP 12 and is repeated. If the predetermined time t0 has elapsed (STEP 17; YES), the start-up control ends, the maximum operating frequency Fmax of the compressor 1 is changed to the control value Fmax2 during normal operation (STEP 18), and the control flow ends.

Here, the control value of the maximum operating frequency Fmax of the compressor 1 is set to satisfy Fmax2> Fmax0> Fmax1.

Embodiment 2. FIG.
The structure of the air conditioning apparatus 200 according to Embodiment 2 of the present invention will be described. In the second embodiment, the description will focus on the differences from the first embodiment, and the description of similar parts will be omitted. The refrigerant circuit, the configuration of the control unit, and the basic operation of the air conditioner 200 are the same as those in the first embodiment.

<< Start-up control method of air conditioner >>
A control operation at startup in the air-conditioning apparatus 200 according to Embodiment 2 will be described with reference to FIG. FIG. 5 is a flowchart showing a flow of control operation at start-up in the air-conditioning apparatus 200 according to Embodiment 2 of the present invention.

After starting the flow, the operation mode (cooling operation / heating operation) of the air conditioner 200 is detected by the measurement unit 30a (STEP 21), and it is determined whether or not the operation mode is the cooling operation mode (STEP 22). If the operation mode is the cooling operation mode (STEP 22; YES), the drive unit 30c sets the maximum operation frequency Fmax of the compressor 1 to the control value Fmax_c during the cooling operation (STEP 23). If it is not the cooling operation mode, that is, if it is the heating operation mode (STEP 22; NO), the drive unit 30c sets the maximum operation frequency Fmax of the compressor 1 to the control value Fmax_h during the heating operation (STEP 24). Thereafter, the compressor 1 is activated by the drive unit 30c, and the time t measurement is started by the measurement unit 30a (STEP 25).

Here, as a refrigeration cycle operation state of a general air conditioner, the refrigerant flow rate is higher in the cooling operation in which the operation is performed in the high outside air temperature condition than in the heating operation in which the operation is performed in the low outside air temperature condition. Become. Therefore, the control value of the maximum operation frequency Fmax is set so that Fmax_c during cooling operation <Fmax_h during heating operation.

Next, in order to determine whether or not the start control of the air conditioner 200 is to be ended, it is determined in the determination unit 30e whether or not the predetermined time t0 has elapsed after the start of the compressor 1 (STEP 26). If the predetermined time t0 has not elapsed (STEP 26; NO), the process returns to STEP 26 and is repeated. If the predetermined time t0 has elapsed (STEP 26; YES), the start-up control is ended, the maximum operating frequency Fmax of the compressor 1 is changed to the control value Fmax2 for normal operation (STEP 27), and the control flow is ended.

Here, the control value of the maximum operating frequency Fmax of the compressor 1 is set to satisfy Fmax2> Fmax_h> Fmax_c.

In addition, although the case of the refrigerant | coolant flow rate determination by operation mode was demonstrated here, as control operation by the refrigerant | coolant flow rate determination + refrigerant | coolant flow rate determination by operation mode as demonstrated in Embodiment 1 based on the detected value of the refrigerant | coolant flow rate Gr. Also good. A specific control operation will be described in the next embodiment.

Embodiment 3 FIG.
The structure of the air conditioning apparatus 300 according to Embodiment 3 of the present invention will be described. In the second embodiment, the difference from the first and second embodiments will be mainly described, and the description of the same portions will be omitted. The refrigerant circuit, the configuration of the control unit, and the basic operation of the air conditioning apparatus 300 are the same as those in the first and second embodiments.

<< Start-up control method of air conditioner >>
A control operation at start-up in the air-conditioning apparatus 300 of the third embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a flow of control operation at start-up in the air-conditioning apparatus 300 according to Embodiment 3 of the present invention.

STEP 31 to STEP 34 are the same operations as STEP 21 to STEP 24 shown in FIG. 5, and the control value of the maximum operating frequency Fmax of the compressor 1 at the initial start-up is set to Fmax_c during the cooling operation depending on whether the operation mode is the cooling operation or the heating operation. / Set to one of Fmax_h during heating operation. The control value of the maximum operating frequency Fmax of the compressor 1 set here is set as the initial value Fmax0, and the compressor 1 is started by the drive unit 30c similarly to STEP 25, and the time t measurement is started by the measurement unit 30a. (STEP 35). Subsequent STEP36 to STEP42 operate in the same manner as STEP12 to STEP18 shown in FIG.

<Effect>
According to the air conditioner according to the present embodiment, an additional element that causes a cost increase such as an oil separator is not required, and a certain amount or more of refrigerating machine oil is supplied into the compressor regardless of operating conditions and operating conditions. Since it becomes possible to ensure the oil-repellency to maintain, a highly reliable air conditioner can be realized.

According to the air conditioner according to the present embodiment, it is possible to suppress the discharge amount of the refrigeration oil that flows out of the compressor together with the refrigerant into the refrigerant circuit by the operation operation. Refrigeration cycle performance degradation associated with storage of water can be avoided, and high performance of the air conditioner can be realized.

In the air conditioner according to the present embodiment, the air conditioner installation conditions such as the length of the refrigerant pipe connecting the outdoor unit and the indoor unit, the height difference of the unit installation location, and the refrigerant charging amount are not included in the compressor. Since it is possible to ensure oil-repellency that maintains a certain amount or more of refrigerating machine oil, it is possible to achieve an increase in the upper limit of the allowable range of installation conditions (such as refrigerant pipe length and height difference of equipment installation location) in the use of air conditioning equipment.

《Cooling device modification》
The features of the present invention have been described in each embodiment. For example, the refrigerant flow path configuration (piping connection), the configuration of refrigerant circuit elements such as a compressor, a heat exchanger, and an expansion valve, etc. The present invention is not limited to the contents described in the embodiments, and can be appropriately changed within the scope of the technology of the present invention.

1 compressor, 2 way valve, 3 outdoor heat exchanger, 4 outdoor blower, 5a decompressor, 5b decompressor, 6 liquid connection pipe, 7 indoor heat exchanger, 8 indoor blower, 9 gas connection pipe, 11 receiver , 12 Internal heat exchanger, 30 control unit, 30a measurement unit, 30b calculation unit, 30c drive unit, 30d storage unit, 30e determination unit, 201 discharge temperature sensor, 202 gas side temperature sensor, 203 outdoor temperature sensor, 204 liquid side Temperature sensor, 205 liquid side temperature sensor, 206 indoor temperature sensor, 207 gas side temperature sensor, 208 compressor shell temperature sensor, A heat source unit, B use unit.

Claims

At least one indoor unit having a compressor, a four-way valve, an outdoor heat exchanger, an outdoor air blower, an outdoor fan having a variable opening degree, an indoor heat exchanger, and an indoor fan that rotatively drives the operating frequency A refrigerant circuit in which the outdoor unit and the indoor unit are connected by a refrigerant pipe, and the compressor, the four-way valve, the outdoor heat exchanger, the decompression device, and the indoor heat exchanger are sequentially connected to circulate the refrigerant. In the air conditioner comprising: the control device for controlling the air conditioning operation of the air conditioner is an operation state detection means for detecting an operation state of the air conditioner; and an operation state detected by the operation state detection means. Based on the refrigerant flow rate determining means for estimating the flow rate of refrigerant circulating through the refrigerant circuit and determining whether or not the operation is performed with a high refrigerant flow rate based on a preset threshold value; If the refrigerant flow rate is determined to greater driving than the predetermined amount by medium flow determining means, the air conditioner being characterized in that a control means for setting lower maximum operating frequency of the compressor.
The operating state detecting means includes a high pressure refrigerant pressure detecting means for detecting a high pressure refrigerant pressure in the refrigerant circuit, a low pressure refrigerant pressure detecting means for detecting a low pressure refrigerant pressure in the refrigerant circuit, and suction of the compressor. An intake temperature detecting means for detecting a refrigerant temperature; and a compressor frequency detecting means for detecting an operating frequency of the compressor, wherein the control device uses the operating state detection value detected by the operating state detecting means. The air conditioner according to claim 1, further comprising a refrigerant flow rate estimating means for estimating a flow rate of refrigerant circulating through the refrigerant circuit.
The operation state detection means has an operation mode detection means for detecting whether the refrigerant circuit is in a cooling operation mode or a heating operation mode, and is detected by the operation mode detection means as being in the cooling operation mode. 3. The air conditioner according to claim 1, wherein the refrigerant flow determination unit determines that the operation is performed with a large refrigerant flow.
The air conditioning apparatus according to any one of claims 1 to 3, wherein the control means sets the maximum operating frequency of the compressor low until a predetermined time elapses after the compressor is started.
The refrigerant circuit has refrigerating machine oil enclosed with a refrigerant, and the control means is configured to control the refrigerating machine oil defined by a ratio of a mass flow rate of the refrigerating machine oil to a total mass flow rate of the refrigerant and the refrigerating machine oil. The air conditioner according to any one of claims 1 to 4, wherein a maximum operation frequency of the compressor is set so that an oil circulation rate is 1.5% or less.
The air conditioner according to any one of claims 1 to 5, wherein the refrigerant pipe connecting the outdoor unit and the indoor unit is a long refrigerant pipe having a total length of 100 m or more.
The air conditioner according to any one of claims 1 to 6, characterized in that the installation position height of the outdoor unit and the indoor unit has a height difference of 30 m or more.