WO2019004112A1

WO2019004112A1 - Refrigerating device

Info

Publication number: WO2019004112A1
Application number: PCT/JP2018/023975
Authority: WO
Inventors: 久瑠美加藤; 圭吾竹本; 優原口; 穂南美山下
Original assignee: ダイキン工業株式会社
Priority date: 2017-06-26
Filing date: 2018-06-25
Publication date: 2019-01-03
Also published as: JP2020139632A

Abstract

The present invention addresses the problem of suppressing, in a refrigerating device provided with a differential pressure-type expansion valve in which the valve opening degree varies according to a pressure difference, defects that are generated when the degree of refrigerant superheating applied to a compressor of the refrigerating device becomes greater than a suitable value or when the degree of refrigerant superheating becomes less than the suitable value. This refrigeration device (10) has a refrigerant circuit (11) configured such that: a refrigerant is circulated in the order of a compressor (31), an outdoor heat exchanger (32) which is a radiator, a differential pressure-type expansion valve (33), and an indoor heat exchanger (21) which is an evaporator; and the flow rate of the refrigerant varies according to a valve opening degree that varies according to the pressure difference between a refrigerant inlet and a refrigerant outlet of the differential pressure-type expansion valve (33). The refrigeration device (10) changes the wind amount of an outdoor fan (32) which is a radiator fan, and/or the wind amount of an indoor fan (22) which is an evaporator fan when the pressure difference is outside a predetermined pressure range, and thereby adjusts the pressure difference to approach the predetermined pressure range and changes the valve opening degree of the differential pressure-type expansion valve (33).

Description

Refrigeration system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus provided with a differential pressure type expansion valve.

Conventionally, differential pressure type expansion valves are known which change the flow rate of refrigerant flowing through the expansion valve according to the pressure difference between the upstream side and the downstream side of the expansion valve. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2004-218918) discloses a differential pressure type expansion valve which controls the refrigerant flow rate by the balance between the differential pressure on the upstream side and downstream side of the valve seat and the biasing force of the spring. ing. If a refrigeration system performing a compression type refrigeration cycle using such a differential pressure type expansion valve is configured, the differential pressure type expansion valve is inexpensive and the differential pressure type expansion valve is not required to be sent to the differential pressure type expansion valve. Since the valve opening degree can be adjusted, the refrigeration system can be provided at low cost.

However, since the change in the valve opening degree of the differential pressure type expansion valve described in Patent Document 1 depends on the differential pressure, compression is performed according to the surrounding conditions of the compressor, the radiator and the evaporator provided in the refrigerant circuit of the refrigeration system When the state of the refrigeration cycle changes, it becomes difficult to control the degree of superheat of the refrigerant related to the compressor. If the degree of superheat of the refrigerant tends to become larger than the appropriate value, the temperature of the refrigerant discharged from the compressor tends to rise, or the evaporator tends to dry, and around the outlet of the air heat-exchanged by the evaporator. Condensation tends to occur. Further, when the degree of superheat of the refrigerant tends to be smaller than the appropriate value, the possibility that the compressor sucks the liquid refrigerant and the compressor breaks down becomes high.

Therefore, in a refrigeration system provided with a differential pressure type expansion valve whose valve opening changes due to differential pressure, the degree of superheat of the refrigerant relating to the compressor of the freezer becomes larger than the appropriate value or conversely the degree of superheat is smaller than the appropriate value There is a problem of suppressing a defect due to becoming

A refrigeration apparatus according to a first aspect includes a compressor, a radiator, a differential pressure type expansion valve, an evaporator, a radiator fan for generating an air flow in the radiator, and an evaporator for generating an air flow in the evaporator. The refrigerant is circulated according to a valve opening degree which is provided with a fan, a refrigerant circulates in the order of a compressor, a radiator, a differential pressure type expansion valve and an evaporator, and is changed according to a differential pressure between a refrigerant inlet and a refrigerant outlet of the differential pressure type expansion valve. A differential pressure is changed toward the predetermined pressure range by changing the air volume of the fan for radiator and / or the fan for evaporator when the refrigerant circuit whose flow rate changes is constituted and the differential pressure deviates from the predetermined pressure range. Change the valve opening degree of the pressure type expansion valve.

According to the refrigeration system according to the first aspect, the air volume of the radiator fan and / or the evaporator fan is changed when the differential pressure between the refrigerant inlet and the refrigerant outlet of the differential pressure type expansion valve deviates from the predetermined pressure range. Since the differential pressure is changed toward the predetermined pressure range to change the valve opening of the differential pressure type expansion valve, the differential pressure is deviated from the predetermined pressure range and the differential pressure becomes too large or too small. Can be prevented.

The refrigeration apparatus according to the second aspect is the refrigeration apparatus according to the first aspect, wherein the air volume of the radiator fan and / or the evaporator fan is changed by adjusting the number of rotations of the radiator fan and / or the evaporator fan. It is a thing.

According to the refrigeration system of the second aspect, control of the change of the air flow rate of the radiator fan and / or the evaporator fan can be easily performed by adjusting the number of rotations of the radiator fan and / or the evaporator fan.

The refrigeration system according to a third aspect is the refrigeration system according to the first aspect or the second aspect, wherein the predetermined pressure range is changed based on the number of rotations of the compressor.

According to the refrigeration apparatus according to the third aspect, the predetermined pressure range is changed according to the number of rotations of the compressor, so that, for example, when the number of rotations of the compressor rises in the steady state and a large amount of refrigerant flows In order to prevent over-squeezing of the valve, the predetermined pressure range is shifted to the high side, for example, when the number of rotations of the compressor decreases and the flow rate of the refrigerant decreases, the predetermined pressure range is The control can be performed with high accuracy, such as shifting to the lower side.

A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the third aspect, wherein the evaporator is installed in the air conditioning target space, and the radiator fan is mounted so that the differential pressure falls within a predetermined pressure range. Change the air volume.

According to the refrigeration apparatus according to the fourth aspect, since the differential pressure falls within the predetermined pressure range by changing the air volume of the radiator fan, the air volume of the evaporator fan can be changed without being restricted by the adjustment of the differential pressure. it can.

A refrigeration apparatus according to a fifth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the third aspect, wherein one of the radiator and the evaporator is installed in the air conditioning target space, and the other is installed in the heat source side space, The air conditioner further includes a first sensor provided to detect a space temperature of the air conditioning target space, which is a change of the air volume of one of the radiator fan and the evaporator fan to be blown in the heat source side space, and the differential pressure is specified. The change in air volume to change towards the pressure range is to use the space temperature detected using at least the first sensor.

According to the refrigeration apparatus according to the fifth aspect, the space temperature is high by changing the air volume of the fan for radiator and the fan for evaporator among the fans on the heat source side using at least the space temperature of the air conditioning target space The degree of opening of the differential pressure type expansion valve can be made larger or smaller in accordance with the situation where it is low.

A refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to the fifth aspect, further comprising a second sensor provided for detecting the ambient temperature of the heat source side space, wherein one of the radiator fan and the evaporator fan Using a temperature difference detected by using the first sensor and the second sensor for changing the air volume for changing the air pressure in the heat source side space for changing the differential pressure toward the predetermined pressure range It is.

According to the refrigeration apparatus according to the sixth aspect, since the differential pressure is adjusted toward the predetermined pressure range based on the temperature difference between the space temperature of the air conditioning target space and the ambient temperature of the heat source side space The air volume can be changed according to the difference between the high pressure value and the low pressure value of the cycle.

A refrigeration apparatus according to a seventh aspect is the refrigeration apparatus according to any one of the first aspect to the fourth aspect, wherein the refrigeration system is provided in a refrigerant circuit for detecting a condensation temperature of a radiator and an evaporation temperature of an evaporator. A sensor is further provided, wherein the condensation temperature and the evaporation temperature detected using at least a third sensor are used to change the air volume of the radiator fan and / or the evaporator fan to change the differential pressure toward the predetermined pressure range. It is a thing.

According to the refrigeration apparatus according to the seventh aspect, since the air flow rate of the radiator fan and / or the evaporator fan is changed using at least the condensing temperature and the evaporating temperature, the difference between the high pressure value and the low pressure value of the refrigeration cycle is small and evaporation occurs. The difference between the high pressure value and the low pressure value of the refrigeration cycle that the refrigerant easily evaporates in the compressor and the situation in which the refrigerant hardly evaporates in the evaporator increase or decrease the valve opening of the differential pressure type expansion valve Can be

A refrigeration apparatus according to an eighth aspect is the refrigeration apparatus according to any one of the first aspect to the fourth aspect, wherein the fourth sensor provided in the refrigerant circuit for detecting the discharge temperature of the refrigerant discharged from the compressor. The discharge temperature detected using at least the fourth sensor is used to change the air volume of the radiator fan and / or the evaporator fan to change the differential pressure toward the predetermined pressure range.

According to the refrigeration system of the eighth aspect, the air flow rate of the radiator fan and / or the evaporator fan is changed using at least the discharge temperature, so that the discharge temperature becomes high and the differential pressure expansion valve is operated even before the safety mechanism works. Valve opening degree can be increased.

The refrigeration apparatus according to a ninth aspect is the refrigeration apparatus according to any of the first aspect to the fourth aspect, one of the radiator and the evaporator is installed in the air conditioning target space, and the other is installed in the heat source side space, The air conditioner further includes a second sensor provided to detect the ambient temperature of the heat source side space, and the air volume of one of the radiator fan and the evaporator fan to be blown to the heat source side space is the number of revolutions of the compressor. It adjusts based on the atmospheric temperature detected using a 2nd sensor.

According to the refrigeration system according to the ninth aspect, the air flow rate is changed based on the number of rotations of the compressor and the ambient temperature detected using the second sensor, so that the radiator fan can be properly operated even within the predetermined pressure range. And the air volume of the direction which blows the air of the heat-source side space among the fans for evaporators can be changed.

The refrigeration apparatus according to a tenth aspect is the refrigeration apparatus according to any one of the first aspect to the ninth aspect, wherein the differential pressure type expansion valve has a main body and a valve body, and the main body is a refrigerant inlet, a refrigerant outlet, and a valve The differential pressure type expansion valve generates static friction between the valve body and the main body to maintain the positional relationship between the valve body and the main body against the biasing force of the biasing member. The valve body is disposed between the refrigerant inlet and the refrigerant outlet, and moves by changing the differential pressure exceeding the limit pressure which keeps the stationary state without moving, thereby changing the valve opening degree. The change in differential pressure towards the predetermined pressure range by adjusting the number of rotations of the radiator fan and / or the evaporator fan is a change exceeding the limit pressure.

According to the refrigeration apparatus according to the tenth aspect, since the change in differential pressure toward the predetermined pressure range by changing the air volume of the radiator fan and / or the evaporator fan is a change exceeding the limit pressure, Although the air volume of the fan for fan and / or the fan for evaporator is changed, the change in differential pressure is small and the valve element of the differential pressure type expansion valve does not move, so the opening degree of the differential pressure type expansion valve is too open or too closed It is possible to prevent the situation from becoming unimprovable.

A refrigeration apparatus according to an eleventh aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the tenth aspect, wherein when the differential pressure exceeds the upper limit value of the predetermined pressure range, the air volume of the radiator fan is increased and the differential pressure is When the pressure is lower than the lower limit value of the predetermined pressure range, the air volume of the radiator fan is reduced.

According to the refrigeration system of the eleventh aspect, the air flow rate of the radiator fan is increased when the differential pressure exceeds the upper limit value of the predetermined pressure range, and when the differential pressure falls below the lower limit value of the predetermined pressure range By reducing the air volume, when the heat exchange efficiency at the radiator decreases and deviates from the predetermined pressure range, the air pressure of the radiator fan is increased or the differential pressure is reduced by decreasing the air volume. Can be changed towards.

A refrigeration apparatus according to a twelfth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the third aspect, further comprising a control device that controls a compressor, a radiator fan and an evaporator fan, the radiator and the evaporator One is installed in the air conditioning target space, the other is installed in the heat source side space, and the control device determines that the differential pressure has deviated from the predetermined pressure range, the space temperature of the air conditioning target space, the ambient temperature of the heat source side space, condensation Direct judgment using at least one of temperature, evaporation temperature, discharge temperature, current value of compressor, or at least one of space temperature, ambient temperature, condensation temperature, evaporation temperature, discharge temperature, current value of compressor The air flow rate of the radiator fan and / or the evaporator fan so that the differential pressure is changed toward the predetermined pressure range when it is determined that the differential pressure has deviated from the predetermined pressure range. It is configured to perform control for changing, those.

According to the refrigeration apparatus according to the twelfth aspect, from the predetermined pressure range using at least one of the space temperature of the air conditioned space, the atmosphere temperature of the heat source side space, the condensation temperature, the evaporation temperature, the discharge temperature, and the current value of the compressor In the case of directly judging that the differential pressure has been released, the control device can omit the process of estimating the differential pressure. Moreover, according to such a refrigeration apparatus, when the differential pressure is estimated and determined using at least one of space temperature, ambient temperature, condensation temperature, evaporation temperature, discharge temperature, and current value of the compressor, Accurate control can be facilitated along the differential pressure.

The refrigeration apparatus according to the thirteenth aspect is the refrigeration apparatus according to any one of the first aspect to the twelfth aspect, wherein the differential pressure is out of the predetermined pressure range when the differential pressure is out of the predetermined pressure range, and the differential pressure is small during the cooling operation. And the superheat degree of the refrigerant sucked and discharged by the compressor exceeds a predetermined value and the superheat degree is too high, and the differential pressure is set to a predetermined pressure by changing the air volume of the radiator fan Varying toward the range includes increasing the differential pressure back to a predetermined pressure range by stopping the radiator fan.

According to the refrigeration apparatus of the thirteenth aspect, when the differential pressure is too small and the degree of superheat of the refrigerant sucked or discharged by the compressor exceeds a predetermined value, the degree of superheat is too high. There is a limitation in changing the rotational speed of the compressor in order to eliminate the state in which the degree of superheat is too high, so stopping the radiator fan makes it easy to eliminate the state in which the degree of superheat is too high.

In the refrigeration apparatus according to the first aspect, the second aspect, the third aspect, the tenth aspect, the eleventh aspect, the twelfth aspect or the thirteenth aspect, the degree of superheat of the refrigerant sucked or discharged from the compressor into the compressor is appropriate It is possible to suppress a defect due to the fact that it is easy to become larger than the value or to make the degree of superheat to easily become smaller than the proper value.

In the refrigeration apparatus according to the fourth aspect, by performing control such that the differential pressure does not deviate from the predetermined pressure range, it is possible to prevent the air conditioning of the air-conditioned space by the evaporator fan from being restricted.

In the refrigeration system according to the fifth aspect, the differential pressure type expansion valve suppresses the valve opening from becoming too small or too large without affecting the air flow in the air-conditioned space and maintaining an appropriate degree of superheat be able to.

In the refrigeration apparatus according to the sixth aspect, the appropriate degree of superheat can be maintained with high accuracy.

In the refrigeration system according to the seventh aspect, it is possible to maintain an appropriate degree of superheat by suppressing the valve opening degree from becoming too small or too large in the differential pressure type expansion valve.

In the refrigeration system according to the eighth aspect, it is possible to maintain an appropriate degree of superheat while preventing the safety mechanism from working due to the valve opening becoming too small in the differential pressure type expansion valve.

The refrigeration apparatus according to the ninth aspect can maintain an appropriate degree of superheat within a predetermined pressure range.

BRIEF DESCRIPTION OF THE DRAWINGS The circuit diagram which shows the outline | summary of a structure of the freezing apparatus which concerns on embodiment. The ph diagram for demonstrating operation | movement of the freezing apparatus of FIG. Typical sectional drawing which shows an example of a structure of a differential pressure type expansion valve. FIG. 5 is a schematic cross-sectional view showing a state in which the valve opening degree of the differential pressure type expansion valve of FIG. 3 has increased. The graph which shows an example of adjustment operation of the valve-opening degree of a differential pressure type expansion valve. The graph which shows an example of the relationship between the rotation speed of an outdoor fan, discharge temperature, and differential pressure. The circuit diagram which shows the outline | summary of a structure of the freezing apparatus which concerns on the modification 1A.

Hereinafter, a refrigeration apparatus according to an embodiment will be described using the drawings. The refrigerant | coolant circuit with which the freezing apparatus which concerns on embodiment is equipped with FIG. 1 is shown. Further, FIG. 2 shows a vapor compression refrigeration cycle performed by the refrigeration system 10 shown in FIG. That is, FIG. 2 shows the relationship between the refrigerant pressure p and the specific enthalpy h for the refrigerant circulating in the refrigerant circuit 11 of the refrigeration system 10.

(1) Overall Configuration The refrigeration system 10 shown in FIG. 1 includes a utilization unit 20 and a heat source unit 30 connected to the utilization unit 20. The usage unit 20 includes an indoor heat exchanger 21 and an indoor fan 22. The heat source unit 30 includes a compressor 31, an outdoor heat exchanger 32, a differential pressure type expansion valve 33, and an outdoor fan 34.

The utilization unit 20 and the heat source unit 30 are connected by refrigerant piping, and a refrigerant circuit 11 for circulating the refrigerant between the utilization unit 20 and the heat source unit 30 is formed. By circulating the refrigerant through the refrigerant circuit 11, the refrigeration apparatus 10 can perform a vapor compression refrigeration cycle.

The refrigerant circuit 11 is configured such that the refrigerant circulates in the order of the compressor 31, the outdoor heat exchanger 32, the differential pressure type expansion valve 33, and the indoor heat exchanger 21. The compressor 31 compresses a gas refrigerant (the refrigerant in the state of point A shown in FIG. 2). The high-temperature and high-pressure refrigerant (refrigerant in the state of point B shown in FIG. 2) that has exited from the discharge port of the compressor 31 flows into the inlet of the outdoor heat exchanger 32. The liquid refrigerant (the refrigerant in the state of point C shown in FIG. 2) heat-exchanged with the outdoor air in the outdoor heat exchanger 32 flows out from the outlet of the outdoor heat exchanger 32, and the differential pressure type expansion valve Flow into the 33 inlet. The refrigerant expanded and reduced in pressure by the differential pressure type expansion valve 33 (the refrigerant in the state of point D shown in FIG. 2) flows out from the outlet of the differential pressure type expansion valve 33 and flows to the inlet of the indoor heat exchanger 21. To flow. The gas refrigerant (refrigerant in the state of point A shown in FIG. 2) heat-exchanged with indoor air in the indoor heat exchanger 21 flows out from the outlet of the indoor heat exchanger 21, and It flows into the suction port.

Here, the refrigeration system is a compressor such as the air conditioner shown in FIG. 1 or FIG. 7 and consumes motive power, and one of the outdoor heat exchanger 32 and the indoor heat exchanger 21. Is a device that takes in heat from the other and discharges heat from the other. In other words, the refrigeration system is an apparatus that performs a refrigeration cycle in a refrigerant circuit. The refrigeration system includes, for example, a heat pump water heater that supplies hot water, a refrigerator, and a cooling system that cools the inside of the refrigerator, in addition to the air conditioner.

(2) Detailed Configuration (2-1) Heat Source Unit Inside the casing (not shown) of the heat source unit 30, the compressor 31, the outdoor heat exchanger 32, the differential pressure type expansion valve 33, the outdoor fan 34 and the discharge temperature sensor An outdoor temperature sensor 36, an outdoor heat exchanger temperature sensor 37, and a heat source side control device 41 are installed. The compressor 31 provided in the heat source unit 30 is a positive displacement compressor whose operating capacity can be changed by the number of rotations, and the number of rotations of the compressor 31 is, for example, a motor 31m whose number of rotations is controlled by an inverter. It is controlled. The motor 31m of the compressor 31 is controlled by a heat source side controller 41 described later.

The outdoor heat exchanger 32 exchanges heat between the outside air flowing into the heat source unit 30 and the refrigerant compressed by the compressor 31. The outdoor heat exchanger 32 is, for example, a cross fin type fin-and-tube heat exchanger, and exchanges heat between the refrigerant passing through a tube (heat transfer tube) and the outside air passing between a large number of fins. Let me do it. That is, the outdoor heat exchanger 32 functions as a radiator during the cooling operation. The refrigerant immediately after flowing into the outdoor heat exchanger 32 is the gas refrigerant in the state of point B shown in FIG. 2. While passing through the outdoor heat exchanger 32, heat is released from the refrigerant, and the gas refrigerant passes through a gas-liquid two-phase state to change to a liquid refrigerant (refrigerant at point C in FIG. 2). The air heat-exchanged by the outdoor heat exchanger 32 is blown out to the outside of the heat source unit 30.

The outdoor fan 34 sends the outside air around the casing of the heat source unit 30 to the outdoor heat exchanger 32. The outdoor fan 34 is a fan capable of changing the air flow rate of the air supplied to the outdoor heat exchanger 32, and is, for example, a propeller fan driven by a motor 34m including a DC fan motor or the like. The number of revolutions of the motor 34 m of the outdoor fan 34 is controlled by the heat source side controller 41.

The discharge temperature sensor 35 is attached to, for example, a discharge pipe of the compressor 31 and detects the temperature of the refrigerant discharged from the compressor 31 (hereinafter also referred to as discharge temperature). The outdoor temperature sensor 36 detects the temperature (ambient temperature) of the outdoor air taken into the casing of the heat source unit 30 by the outdoor fan 34. The outdoor heat exchanger temperature sensor 37 detects the temperature of the portion of the outdoor heat exchanger 32 in the gas-liquid two-phase state. That is, the outdoor heat exchanger temperature sensor 37 detects the condensation temperature of the refrigerant in the outdoor heat exchanger 32.

The heat source side controller 41 controls the compressor 31 and the outdoor fan 34 as described above. The heat source side controller 41 is connected to the use side controller 42. The heat source side control device 41 and the use side control device 42 constitute a control device 40 of the refrigeration system 10. For the controller 40, for example, a controller can be used. The control device 40 includes a CPU (not shown) and a memory (not shown), and controls each device of the refrigeration system 10 by executing a program stored in the memory. The control device 40 controls the on / off and rotational speed of the compressor 31 and the outdoor fan 34 according to, for example, information on thermo-off and thermo-on, information on the difference between the set temperature and the indoor temperature, and information on the outdoor temperature. The heat source side controller 41 includes a timer 43. The control device 40 can measure the timing of control by means of the timer 43.

(2-1-1) Differential pressure type expansion valve 33
The differential pressure type expansion valve 33 changes the flow rate of the refrigerant circulating in the refrigerant circuit 11 by changing the valve opening degree. In the differential pressure type expansion valve 33, the valve opening changes in accordance with the differential pressure applied to the differential pressure type expansion valve 33, that is, the differential pressure between the refrigerant inlet 61 and the refrigerant outlet 62 of the differential pressure type expansion valve 33 described later. In other words, the differential pressure type expansion valve 33 is controlled by the differential pressure between the refrigerant inlet 61 and the refrigerant outlet 62.

The configuration of the differential pressure type expansion valve 33 is schematically shown in FIGS. 3 and 4. The differential pressure type expansion valve 33 includes a main body 51 and a valve body 52. In the main body 51 of the differential pressure type expansion valve 33, a refrigerant inlet 61 where the refrigerant flows from the refrigerant circuit 11 into the differential pressure type expansion valve 33, and a refrigerant outlet where the refrigerant flows out from the inside of the differential pressure type expansion valve 33 to the refrigerant circuit 11. 62 are provided. The pressure of the refrigerant at the refrigerant inlet 61 is substantially the pressure P1 at point C in FIG. 2, and the pressure of the refrigerant at the refrigerant outlet 62 is substantially the pressure P2 at point D in FIG. Here, in order to simplify the description, the decrease in the pressure of the refrigerant generated in the piping of the refrigerant circuit 11 and the like is ignored. As the refrigerant passes through the differential pressure type expansion valve 33, the pressure decreases and the pressure P1 becomes the pressure P2. That is, the differential pressure type expansion valve 33 functions as a pressure reducing mechanism that reduces the pressure of the refrigerant.

The shape of the main body 51 is, for example, a cylinder. When the main body 51 is cylindrical, the differential pressure expansion valve 33 can be easily installed in the cylindrical pipe that constitutes the refrigerant circuit 11. A valve body 52 is disposed between the refrigerant inlet 61 and the refrigerant outlet 62. In more detail, a valve body 52 is movably disposed in a cavity 63 inside the main body 51 connecting the refrigerant inlet 61 and the refrigerant outlet 62.

The main body 51 has a coil spring 53 that supports the valve body 52. The coil spring 53 applies a biasing force to the valve body 52. The biasing force that the coil spring 53 applies to the valve body 52 is a force that pushes the valve body 52 in the direction from the refrigerant outlet 62 to the refrigerant inlet 61. When the differential pressure (P1-P2) between the refrigerant inlet 61 and the refrigerant outlet 62 is small, as shown in FIG. 3, the valve body 52 moves toward the refrigerant inlet 61, and the valve opening degree is small. Become. Conversely, when the differential pressure (P1-P2) between the refrigerant inlet 61 and the refrigerant outlet 62 is large, as shown in FIG. 4, the valve body 52 moves to the refrigerant outlet 62 and the valve is opened. The degree gets bigger.

In the valve body 52, an in-valve flow path FC1 having a cross-sectional area S1 is formed at the narrowest portion. The cross-sectional area S1 is an area of a cross section cut by a plane perpendicular to the flow direction of the in-valve channel FC1. The outer dimensions of the valve body 52 are smaller than the dimensions of the cavity 63 of the main body 51. Therefore, a gap is created between the valve body 52 and the main body 51. This gap becomes the non-valve flow path FC2. The out-of-valve flow path FC2 has a cross-sectional area S2 at the narrowest portion.

The relationship between the differential pressure applied to the differential pressure type expansion valve 33 and the flow rate of the differential pressure type expansion valve 33 is shown in FIG. The valve body 52 is in contact with the narrow portion 51a of the main body 51 until the differential pressure increases and exceeds the differential pressure DP6 shown in FIG. 5, as shown in FIG. Thus, when the valve body 52 is in contact with the narrow portion 51a, the refrigerant flows in the in-valve flow path FC1. The refrigerant flow passage area of the in-valve flow passage FC1 is the cross-sectional area S1 of the minimum area. At this time, the valve opening degree becomes the smallest.

When the differential pressure increases and exceeds the differential pressure DP6, the distance between the narrow portion 51a and the valve body 52 widens. The cross-sectional area S2 of the out-of-valve flow path FC2 is added to the cross-sectional area S1 of the in-valve flow path FC1 in a state where the distance between the narrow portion 51a and the valve body 52 is expanded most. That is, when the valve body 52 is separated from the narrow portion 51a, the valve opening degree is increased, and the refrigerant passage area of the differential pressure type expansion valve 33 is the largest area when the valve opening degree is maximized (S1 + S2) become.

The differential pressure type expansion valve 33 basically maintains the balance between the biasing force generated by the coil spring 53 and the differential pressure as the valve body 52 moves. Then, as the valve body 52 moves, the valve opening changes as described above. However, when the biasing force generated by the coil spring 53 and the differential pressure move by balancing, chattering in which the valve opening degree fluctuates due to small fluctuation of the differential pressure is generated. In order to prevent such chattering, for example, a leaf spring 54 that generates static friction is provided on the valve body 52 so as to be disposed between the valve body 52 and the main body 51. The leaf spring 54 is in contact with the inner surface of the cavity 63 of the main body 51. That is, a static friction force is generated between the main body 51 and the valve body 52 by the plate spring 54. Although such static friction causes a hysteresis, such a hysteresis is ignored here for the sake of easy understanding of the embodiment. However, even if such a hysteresis occurs, the application of the concept of the present embodiment is possible.

(2-2) Use Unit Inside the casing (not shown) of the use unit 20, the indoor heat exchanger 21, the indoor fan 22, the indoor temperature sensor 23, the temperature sensor 24 for the indoor heat exchanger, and the use side control device 42. Is installed. The indoor heat exchanger 21 is an air heat exchanger that performs heat exchange between air and a refrigerant, and is, for example, a fin-and-tube type heat exchange of cross fin type constituted by a heat transfer tube and a large number of fins. It is In the indoor heat exchanger 21, heat exchange is performed between the refrigerant of the refrigerant circuit 11 flowing in the inside of the tube (heat transfer pipe) and the indoor air passing between the fins. Therefore, the indoor heat exchanger 21 functions as an evaporator of the refrigerant during the cooling operation to cool the indoor air.

The indoor fan 22 of the utilization unit 20 sucks indoor air into the casing, exchanges heat with the refrigerant in the indoor heat exchanger 21, and then functions as a blower supplying the air after heat exchange into the room as supply air. . The indoor fan 22 is, for example, a centrifugal fan or a multiblade fan, and in the usage unit 20 illustrated in FIG. 1, for example, a cross flow fan is used. The indoor fan 22 is a fan capable of changing the air volume of the air supplied to the indoor heat exchanger 21 in a predetermined air volume range, and is driven by, for example, a motor 22 m including a DC fan motor or the like. The motor 22m is controlled by the use side control device 42. The indoor temperature sensor 23 detects the temperature of indoor air taken into the casing of the usage unit 20 by the indoor fan 22. The indoor heat exchanger temperature sensor 24 detects the temperature (for example, the same temperature as the temperature of the refrigerant at the point D) of the portion in the indoor heat exchanger 21 in the gas-liquid two-phase state. That is, the indoor heat exchanger temperature sensor 24 detects the evaporation temperature of the refrigerant in the indoor heat exchanger 21.

The use-side control device 42 performs control of thermo-on and thermo-off as the control device 40 in addition to the control of the indoor fan 22 described above. To that end, the user-side control device 42 includes an input device such as a remote controller (not shown). The user inputs the set temperature using the remote controller.

(3) Operation of Refrigerating Apparatus 10 The refrigerating apparatus 10 is an apparatus dedicated to cooling, and is controlled by the control device 40 so that the indoor temperature becomes a set temperature. In the refrigeration apparatus 10, in order to prevent the liquid refrigerant from being drawn into the compressor 31, for example, the refrigerant drawn into the compressor 31 is controlled to be substantially in the superheated state. Here, the term "superheated state" means that the gas-liquid two-phase state may temporarily be allowed, but the gas-liquid two-phase state is not always established. In the refrigeration apparatus 10 shown in FIG. 1, the degree of superheat of the refrigerant discharged from the compressor 31 is controlled to maintain an appropriate range. The controller 40 controls the number of rotations of the compressor 31 and / or the number of rotations of the outdoor fan 34 in order to set the degree of superheat of the refrigerant to the target degree of superheat. The control for changing the number of rotations of the compressor 31 and / or the number of rotations of the outdoor fan 34 in this case is, for example, a control that changes the number of rotations stepwise. Alternatively, a period in which the rotational speed of the outdoor fan 34 is constant tends to occur.

Further, when the difference between the indoor temperature detected by the indoor temperature sensor 23 and the set temperature is large, the control device 40 increases the rotational speed of the compressor 31, and when the difference between the indoor temperature and the set temperature is small, the compressor 31 Control to reduce the rotation speed of Since the cooling capacity increases as the rotation speed of the compressor 31 increases, the room temperature can be brought close to the set temperature even if the cooling load is large. For example, when the rotation speed of the compressor 31 changes according to the difference between the indoor temperature and the set temperature, the rotation speed of the outdoor fan 34 changes according to the rotation speed of the compressor 31 and the temperature of the outdoor air (ambient temperature). To be controlled.

(3-1) Adjustment Operation of Valve Opening In the normal operation, for example, the control device 40 compresses the refrigeration apparatus 10 so that the discharge superheat degree matches the target superheat degree according to the first table stored in the control device 40. The rotation speed of the machine 31 is controlled. In a first table stored in the control device 40, the set temperature, the indoor temperature (the detection value of the indoor temperature sensor 23), the discharge temperature (the detection value of the discharge temperature sensor 35), etc. The relationship is described. The control device 40 reads the description of this relation, and changes the rotation speed of the compressor 31 according to the situation.

For example, if the difference between the set temperature and the temperature of the indoor room is a first value and the flow rate flowing to the differential pressure type expansion valve 33 is FR0, the differential pressure type expansion is operated if it is operated in an appropriate refrigeration cycle. The differential pressure applied to the valve 33 is stable in the vicinity of DP1 (see FIG. 5), and the controller 40 can control the operation of the refrigeration system 10 without departing from the predetermined pressure range SC1 (see FIG. 5).

Then, if the room temperature approaches the set temperature by continuing the operation of the refrigeration system 10 and the temperature decreases to a second value where there is a difference between the set temperature and the room temperature, the cooling capacity is reduced. Therefore, the control device 40 reduces the rotational speed of the compressor 31 to reduce the circulation amount of the refrigerant flowing to the refrigerant circuit 11. In this case, if operating in an appropriate refrigeration cycle, the differential pressure applied to the differential pressure type expansion valve 33 is stable in the vicinity of DP2 (see FIG. 5), and the controller 40 controls the rotational speed of the compressor 31 to The operation of the refrigeration system 10 can be controlled without departing from the predetermined pressure range SC2 (see FIG. 5) which is also changed.

Further, for example, immediately after the start of operation of the refrigeration apparatus 10, when the difference between the room temperature and the set temperature is a third value that is large, the control device 40 increases the number of revolutions of the compressor 31 significantly. Increase the cooling capacity. In this case, if operating in an appropriate refrigeration cycle, the differential pressure applied to the differential pressure type expansion valve 33 is stable in the vicinity of DP3 (see FIG. 5), and the controller 40 controls the rotational speed of the compressor 31 to The operation of the refrigeration system 10 can be controlled without departing from the predetermined pressure range SC3 (see FIG. 5) which is also changed.

When the control device 40 performs the control as described above in the normal operation, the valve opening degree of the differential pressure type expansion valve 33 is set to a predetermined pressure range SC1, SC2, SC3 set based on the rotational speed of the compressor 31. It is set to fit within the range. Therefore, the differential pressure of the differential pressure type expansion valve 33 in the state where the operation of the refrigeration system 10 is stable becomes the differential pressure in the predetermined pressure range SC1, SC2, SC3.

(3-2) Adjustment Operation of Valve Opening at Abnormal Time However, the differential pressure of the differential pressure type expansion valve 33 is greatly influenced by the environment in which the refrigeration system 10 is placed, particularly the indoor temperature and the outdoor temperature. Since the differential pressure of the differential pressure type expansion valve 33 is affected by the environment, it may be difficult to control the differential pressure of the differential pressure type expansion valve 33 by the rotational speed of the compressor 31 depending on the environment where the refrigeration system 10 is placed. Sometimes. As described above, when the differential pressure of the differential pressure type expansion valve 33 can not be sufficiently controlled depending on the rotational speed of the compressor 31, it is an abnormal time.

(3-2-1) The case where the differential pressure becomes too small In the cooling operation, when the indoor temperature of the room which is the air conditioning target space is the same degree as or higher than the outdoor temperature of the outdoor which is the heat source side space, differential pressure type The differential pressure of the expansion valve 33 may be too small for a predetermined pressure range. For example, assuming that the set temperature is 18 ° C. and the room temperature is 27 ° C. is the case where the difference between the set temperature and the room temperature described above is the third value, the refrigeration apparatus 10 operates in an appropriate refrigeration cycle. If so, the differential pressure of the differential pressure type expansion valve 33 is stabilized in the vicinity of DP3 and can be controlled within the range of the predetermined pressure range SC3. However, for example, when the indoor temperature and the outdoor temperature are both 27 ° C. during the cooling operation at the set temperature of 18 ° C., the differential pressure may become so small that it deviates from the appropriate predetermined pressure range SC3. For example, when the differential pressure of the differential pressure type expansion valve 33 reaches the differential pressure DP4 shown in FIG. 5, the valve opening degree decreases and the refrigerant flow rate of the refrigerant circuit 11 decreases to FR1. The rotational speed of the compressor 31 at this time is appropriate as long as the flow rate of the refrigerant circulating through the refrigerant circuit 11 is in the range RA1. However, when the flow rate of the refrigerant decreases to FR1, the indoor heat exchanger 21 becomes dry easily and the room The degree of superheat of the refrigerant coming out of the heat exchanger 21 and sucked into the compressor 31 becomes large, the discharge temperature of the refrigerant discharged from the compressor 31 becomes high, and the compressor 31 can not be operated.

For example, when the differential pressure type expansion valve 33 of the refrigerant circuit 11 of FIG. 1 is replaced with a motor operated valve under the same conditions, the valve opening degree of the motor operated valve can be controlled regardless of the differential pressure applied to the motored valve. The discharge temperature of the refrigerant discharged from the nozzle is about 58.degree. However, when the differential pressure type expansion valve 33 is operated under the same conditions, the discharge temperature of the refrigerant discharged from the compressor 31 is about 103 ° C.

The control device 40 detects or estimates that the differential pressure of the differential pressure type expansion valve 33 has deviated from the predetermined pressure range SC3 by a method described in (3-3) described later or the like. When determining that the differential pressure of the differential pressure type expansion valve 33 has deviated from the predetermined pressure range SC3, the control device 40 performs control to change the differential pressure of the differential pressure type expansion valve 33 toward the predetermined pressure range SC3. In the case described above, the control device 40 performs control to raise the differential pressure of the differential pressure type expansion valve 33 toward DP3 because the value falls below the lower limit LDP of the predetermined pressure range SC3. For example, in order to raise the differential pressure of the differential pressure type expansion valve 33 toward DP 3, the control device 40 performs control to lower the rotational speed of the outdoor fan 34.

FIG. 6 shows a curve C1 showing a change in differential pressure when the rotation speed of the outdoor fan 34 is changed, and a curve C2 showing a change in discharge temperature. For example, in the case where the characteristics shown in FIG. 6 are present, the discharge temperature is about at the point when the control device 40 detects that the differential pressure of the differential pressure type expansion valve 33 falls below the lower limit LDP of the predetermined pressure range SC3. Assuming that the rotational speed of the outdoor fan 34 is 890 rpm at 103 ° C., the controller 40 can lower the discharge temperature to about 66 ° C. by reducing the rotational speed of the outdoor fan 34 to 340 rpm.

It is considered that the system is configured to limit the increase in the rotational speed of the compressor 31 in order to protect the compressor 31 when the refrigeration system 10 reaches a predetermined discharge temperature or more. The rotation speed of the compressor 31 at which the discharge temperature of the compressor 31 of the refrigeration apparatus 10 reaches the upper limit under the same environmental conditions (for example, the indoor temperature and the outdoor temperature is 27 ° C. and the set temperature 18 ° C.) Is approximately doubled at 340 rpm compared to the case of 890 rpm. That is, in the case of a severe environmental condition for the refrigeration apparatus 10, the control device 40 can widen the operable range of the compressor 31 by reducing the rotational speed of the outdoor fan 34.

(3-2-2) The case where the differential pressure becomes too large In the cooling operation, if the outdoor temperature outside the heat source space is very high with respect to the room temperature inside the air conditioning target space, the differential pressure type expansion valve The differential pressure of 33 may be too high for a given pressure range. For example, when the set temperature is 18 ° C. and the room temperature is 23 ° C., the difference between the set temperature and the room temperature described above is the second value, and the refrigeration system 10 is operated in an appropriate refrigeration cycle. Then, the differential pressure of the differential pressure type expansion valve 33 can be stably controlled in the vicinity of DP2 and can be controlled within the range of the predetermined pressure range SC2. However, for example, when the room temperature is 21 ° C. and the outdoor temperature is 46 ° C. during the cooling operation at a set temperature of 18 ° C., the differential pressure may become so large that it deviates from the appropriate predetermined pressure range SC2. . For example, when the differential pressure of the differential pressure type expansion valve 33 reaches the differential pressure DP5 shown in FIG. 5, the valve opening degree is increased and the refrigerant flow rate of the refrigerant circuit 11 is increased to FR2. The rotational speed of the compressor 31 at this time is appropriate as long as the flow rate of the refrigerant circulating through the refrigerant circuit 11 is in the range of RA2, but when the flow rate of the refrigerant increases to FR2, the indoor heat exchanger 21 exits the indoor heat exchanger 21 and the compressor 31 The degree of superheat of the refrigerant drawn into the air becomes so small that liquid return to the compressor 31 easily occurs. For example, when the differential pressure type expansion valve 33 of the refrigerant circuit 11 of FIG. 1 is replaced with a motor operated valve under the same conditions, the valve opening degree of the motor operated valve can be controlled regardless of the differential pressure applied to the motored valve. Is approximately 32 deg, while the discharge superheat degree is approximately 17 deg when the differential pressure type expansion valve 33 is operated under the same conditions.

When the differential pressure of the differential pressure type expansion valve 33 exceeds the upper limit value UDP of the predetermined pressure range SC2, the control device 40 performs control to lower the differential pressure of the differential pressure type expansion valve 33 toward DP2. For example, the control device 40 performs control to increase the rotational speed of the outdoor fan 34 in order to lower the differential pressure of the differential pressure type expansion valve 33 toward DP2.

Although (3-2-1) and (3-2-2) have described the case where the differential pressure deviates from the predetermined pressure range SC2, SC3, the differential pressure may deviate from the predetermined pressure range SC1. Even when the differential pressure deviates from the predetermined pressure range SC1, as described in (3-2-1) and (3-2-2), the rotational speed of the outdoor fan 34 is changed to set the predetermined pressure range SC1. The control device 40 may perform control so that the differential pressure falls within the range. Further, when the differential pressure is increased outside the predetermined pressure range SC3 and the differential pressure is decreased outside the predetermined pressure range SC2, the number of rotations of the outdoor fan 34 is similarly changed to fall within the predetermined pressure range SC1. The controller 40 may be configured to perform control so that the differential pressure is contained.

Also, three cases of the predetermined pressure range SC1 to SC3 have been described as the case of performing control to change the differential pressure toward the predetermined pressure range by adjusting the number of rotations of the radiator fan and / or the evaporator fan. Usually, for example, between the differential pressure DP1 and the differential pressure DP2 and also between the differential pressure DP1 and the differential pressure DP3, as shown by a two-dot chain line in FIG. It is set. The two-dot chain line may be a straight line, but the two-dot chain line may be curved or stepped so that the width of the predetermined pressure range changes depending on the magnitude of the differential pressure. The above-described control may be partially performed instead of the whole. For example, the number of rotations of the radiator fan and / or the evaporator fan may be adjusted only between the differential pressure DP1 and the differential pressure DP3. Thus, control may be performed to change the differential pressure toward a predetermined pressure range, and the above-described control may not be performed between the differential pressure DP1 and the differential pressure DP2.

(3-3) Judgment for returning differential pressure to predetermined pressure range (3-3-1) Judgment using indoor temperature The control device 40 has, for example, the differential pressure of the differential pressure type expansion valve 33 from the predetermined pressure range SC. It is determined using the difference between the detection values of the indoor temperature sensor 23 and the outdoor temperature sensor 36, that is, the temperature difference between the indoor temperature and the outdoor temperature. As described in (3-1) above, the differential pressure is smaller than the lower limit LDP of the predetermined pressure range SC3 when the outdoor temperature and the indoor temperature are the same temperature or when the indoor temperature is higher than the outdoor temperature Sometimes. However, for example, when the indoor temperature and the outdoor temperature become equal, the differential pressure is not always smaller than the lower limit LDP of the predetermined pressure range SC3. For example, whether the differential pressure is smaller than the lower limit LDP also differs depending on the set temperature during cooling operation and the performance and design of the device. Therefore, for example, conditions under which the differential pressure is smaller than the lower limit LDP of the predetermined pressure range SC3 are previously examined using an actual machine or simulation. Then, data based on the preliminary examination result is stored in the control device 40. If the temperature difference between the indoor temperature and the outdoor temperature satisfies a predetermined condition under a specific condition of a specific device based on a program using such data, the control device 40 determines that the differential pressure is smaller than the lower limit LDP. In order to judge and raise the differential pressure, the number of rotations of the outdoor fan 34 is reduced to a predetermined number of rotations.

Similarly, also in the case where the outdoor temperature is very high relative to the indoor temperature, for example, conditions that make the differential pressure higher than the upper limit value UDP of the predetermined pressure range SC2 are examined in advance using a real machine or simulation. Then, data based on the preliminary examination result is stored in the control device 40. If the temperature difference between the indoor temperature and the outdoor temperature satisfies a predetermined condition under a specific condition of a specific device based on a program using such data, the control device 40 determines that the differential pressure is larger than the upper limit value UDP. In order to lower the differential pressure, the number of rotations of the outdoor fan 34 is increased to a predetermined number of rotations.

In addition, outdoor temperature is used for determination of the rotation speed of the outdoor fan 34 with the rotation speed of the compressor 31, as already demonstrated, for example. As described above, since the outdoor temperature is already used to determine the rotational speed of the outdoor fan 34, instead of using the temperature difference between the outdoor temperature and the indoor temperature, the outdoor fan according to the conventional rotational speed of the compressor 31 and the outdoor temperature The rotational speed of the outdoor fan 34 may be determined in consideration of the room temperature in addition to the method of determining the rotational speed of 34. As a method of determining the rotation speed of the outdoor fan 34 in consideration of the room temperature, there is, for example, a method of correcting the determined value of the rotation speed of the outdoor fan 34 based on the room temperature.

(3-3-2) Judgment Using Detection Value Related to Differential Pressure In the above (3-3-1), the room temperature is used to control the rotational speed of the outdoor fan 34 for returning the differential pressure to the predetermined pressure range SC. However, alternatively or additionally, the rotational speed of the outdoor fan 34 may be controlled using a differential pressure related detection value. Therefore, the control device 40 estimates the differential pressure between the refrigerant inlet 61 and the refrigerant outlet 62 of the differential pressure type expansion valve 33 from the condensation temperature of the outdoor heat exchanger 32 and the evaporation temperature of the indoor heat exchanger 21 to estimate it. The control may be performed by determining whether or not the pressure difference is out of the predetermined pressure range SC using the pressure difference.

In the refrigerant circuit 11 shown in FIG. 1, the refrigerant in the gas-liquid two-phase state between the point B and the point C in FIG. 2 appears in the outdoor heat exchanger 32. The controller 40 measures the temperature of the refrigerant in the gas-liquid two-phase state in the outdoor heat exchanger 32 by the outdoor heat exchanger temperature sensor 37. Since the temperature of the refrigerant in the gas-liquid two-phase state between the point B and the point C is the condensation temperature, the pressure P1 shown in FIG. 2 can be obtained from the relationship between the condensation temperature of the specific refrigerant and the pressure. Further, in the refrigerant circuit 11, the refrigerant in the gas-liquid two-phase state between the point D and the point A in FIG. 2 appears in the indoor heat exchanger 21. The controller 40 measures the temperature of the refrigerant in the gas-liquid two-phase state in the indoor heat exchanger 21 by the temperature sensor 24 for the indoor heat exchanger. Since the temperature of the refrigerant in the gas-liquid two-phase state between the point D and the point A is the evaporation temperature, the pressure P2 shown in FIG. 2 can be obtained from the relationship between the evaporation temperature and the pressure of a specific refrigerant. The differential pressure between the refrigerant inlet 61 and the refrigerant outlet 62 of the differential pressure type expansion valve 33 is substantially the pressure difference (P1-P2) between the point C and the point D. In this case, both the outdoor heat exchanger temperature sensor 37 and the indoor heat exchanger temperature sensor 24 constitute a third sensor for detecting the condensation temperature and the evaporation temperature.

Therefore, if the control device 40 is configured to store the second table for obtaining the pressure from the condensation temperature and the evaporation temperature in the internal memory (not shown), the temperature sensor 37 for outdoor heat exchanger and the indoor heat exchange The controller 40 can monitor the differential pressure of the differential pressure type expansion valve 33 using the temperature detected by the instrumental temperature sensor 24. If the control device 40 performs such monitoring and determines that the differential pressure has become smaller than the lower limit LDP, the rotational speed of the outdoor fan 34 is increased to a predetermined rotational speed in order to increase the differential pressure. Reduce. Further, if the control device 40 determines that the differential pressure becomes larger than the upper limit value UDP under such monitoring, the number of rotations of the outdoor fan 34 is set in advance to lower the differential pressure. Raise to.

(3-3-3) Judgment Using Discharge Temperature In the case of (3-3-1) described above, the case where the indoor temperature is used to control the rotational speed of the outdoor fan 34 for returning the differential pressure to the predetermined pressure range SC3 In the above (3-3-2), the control of the rotational speed of the outdoor fan 34 for returning the differential pressure to the predetermined pressure range SC2 has been described using differential pressure related detection values. Alternatively or additionally, the discharge temperature may be used to control the rotational speed of the outdoor fan 34. To that end, the control device 40 may be configured to perform control by determining whether or not it has deviated from the predetermined pressure range SC using the discharge temperature.

The above (3-2-1) has described the case where the differential pressure becomes too small. As can be understood from this description, when the differential pressure deviates so as to fall below the lower limit LDP of the predetermined pressure range SC, the discharge temperature of the refrigerant discharged from the compressor 31 as a result rises abnormally. Conversely, the control device 40 may be configured to determine that the differential pressure falls below the lower limit LDP of the predetermined pressure range SC due to an abnormal increase in the discharge temperature of the refrigerant.

(4) Modification (4-1) Modification 1A
Although the case where the refrigeration system 10 is dedicated to cooling is described in the above embodiment, the concept of the above embodiment can be applied to the refrigeration system 10A dedicated to heating as shown in FIG. 7.

(4-1-1) Overall Configuration The refrigeration system 10A shown in FIG. 7 includes a utilization unit 20 and a heat source unit 30 connected to the utilization unit 20. The usage unit 20 includes an indoor heat exchanger 21 and an indoor fan 22. The heat source unit 30 includes a compressor 31, an outdoor heat exchanger 32, a differential pressure type expansion valve 33, and an outdoor fan 34. The utilization unit 20 and the heat source unit 30 are connected by a refrigerant pipe, and a refrigerant circuit 11A that circulates the refrigerant between the utilization unit 20 and the heat source unit 30 is formed. By circulating the refrigerant through the refrigerant circuit 11A, the refrigeration system 10A can perform a vapor compression refrigeration cycle.

The refrigerant circuit 11A is configured such that the refrigerant circulates in the order of the compressor 31, the indoor heat exchanger 21, the differential pressure type expansion valve 33, and the outdoor heat exchanger 32. The compressor 31 compresses a gas refrigerant (the refrigerant in the state of point A shown in FIG. 2). The high-temperature and high-pressure refrigerant (refrigerant in the state of point B shown in FIG. 2) that has exited from the discharge port of the compressor 31 flows into the inlet of the indoor heat exchanger 21. The liquid refrigerant (refrigerant in the state of point C shown in FIG. 2) heat-exchanged with the indoor air in the indoor heat exchanger 21 flows out from the outlet of the indoor heat exchanger 21, and the differential pressure type expansion valve Flow into the 33 inlet. The refrigerant expanded and reduced in pressure by the differential pressure type expansion valve 33 (the refrigerant in the state of point D shown in FIG. 2) flows out from the outlet of the differential pressure type expansion valve 33 and flows to the inlet of the outdoor heat exchanger 32. To flow. The gas refrigerant (refrigerant in the state of point A shown in FIG. 2) heat-exchanged with the outdoor air in the outdoor heat exchanger 32 flows out from the outlet of the outdoor heat exchanger 32, and It flows into the suction port.

In the refrigeration system 10A shown in FIG. 7, heating of the room which is the space to be air conditioned is performed. In such a refrigeration system 10A, the indoor heat exchanger 21 functions as a radiator (or a condenser), and the outdoor heat exchanger 32 functions as an evaporator.

(4-1-2) Operation of Refrigeration Apparatus 10A The refrigeration apparatus 10A is an apparatus dedicated to heating, and is controlled by the control device 40 so that the indoor temperature becomes a set temperature. In the refrigeration apparatus 10A, in order to prevent the liquid refrigerant from being drawn into the compressor 31, for example, the refrigerant drawn into the compressor 31 is controlled so as to be substantially in a superheated state. In the refrigeration apparatus 10A shown in FIG. 7, the control device 40 controls the degree of superheat of the refrigerant detected by the discharge temperature sensor 35 to be the target degree of superheat, so that the refrigerant sucked from the compressor 31 The degree of discharge superheat is controlled to maintain an appropriate range. The controller 40 controls the number of revolutions of the compressor 31 and / or the number of revolutions of the outdoor fan 34 in order to bring the temperature of the refrigerant to the target degree of superheat.

Further, when the difference between the indoor temperature detected by the indoor temperature sensor 23 and the set temperature is large, the control device 40 increases the rotational speed of the compressor 31, and when the difference between the indoor temperature and the set temperature is small, the compressor 31 Control to reduce the rotation speed of Since the heating capacity increases as the rotation speed of the compressor 31 increases, the indoor temperature can be brought close to the set temperature even if the heating load is large.

(4-1-3) Adjustment Operation of Valve Opening In the normal operation, the refrigeration apparatus 10A also adjusts the discharge superheat degree to the target superheat degree according to the third table stored in the control device 40, similarly to the refrigeration apparatus 10 In addition, the control device 40 is configured to control, for example, the number of rotations of the compressor 31. In a third table stored in the control device 40, the set temperature, the indoor temperature (the detected value of the indoor temperature sensor 23), the discharge temperature (the detected value of the discharge temperature sensor 35), etc. The relationship is described. The control device 40 reads the description of this relation, and changes the rotation speed of the compressor 31 according to the situation.

(4-1-4) Adjustment Operation of Valve Opening at Abnormal Time Even in the heating operation, the differential pressure of the differential pressure type expansion valve 33 may be too small relative to the predetermined pressure range. The control device 40 that detects or estimates that the differential pressure of the differential pressure type expansion valve 33 has deviated from the predetermined pressure range determines that the differential pressure of the differential pressure type expansion valve 33 has deviated, the differential pressure type expansion valve 33 Control of changing the differential pressure of the pressure sensor to a predetermined pressure range. The control device 40 performs control to increase the differential pressure of the differential pressure type expansion valve 33 when the pressure falls below the lower limit value of the predetermined pressure range. For example, in order to raise the differential pressure of the differential pressure type expansion valve 33, the control device 40 performs control to lower the rotational speed of the outdoor fan 34.

In the heating operation, the differential pressure of the differential pressure type expansion valve 33 may be too large for a predetermined pressure range. The control device 40 performs control to lower the differential pressure of the differential pressure type expansion valve 33 when the differential pressure of the differential pressure type expansion valve 33 exceeds the upper limit value of the predetermined pressure range. For example, in order to lower the differential pressure of the differential pressure type expansion valve 33, the control device 40 performs control to increase the rotational speed of the outdoor fan 34.

The determination for returning the differential pressure in the heating operation to the predetermined pressure range is the same as the determination for returning the differential pressure in the cooling operation described in (3-3) above to the predetermined pressure range in the control device 40. It can be carried out.

(4-2) Modified Example 1B
In the description of the refrigeration system 10 of the above embodiment and the refrigeration system 10A of the modification 1A, the pair type in which one utilization unit 20 is connected to one heat source unit 30 has been described, but the refrigeration system The configuration of is not limited to the pair type, and the concept of the above embodiment can be applied to a multi type in which a plurality of utilization units are connected to the heat source unit.

(4-3) Modified Example 1C
Although the case where the differential pressure type expansion valve 33 is provided in the heat source unit 30 has been described in the embodiment and the modified example 1A, the differential pressure type expansion valve 33 may be provided in the usage unit 20, and the usage unit 20 and the heat source unit It may be disposed in

refrigerant circuits

11 and 11A other than 30.

(4-4) Modified Example 1D
Although the case where the refrigeration apparatus 10 is dedicated to cooling or the refrigeration apparatus 10A is dedicated to heating has been described in the above embodiment and modification 1A, the above description also applies to a refrigeration apparatus configured to perform both cooling and heating. The idea of the embodiment can be applied.

(4-5) Modified Example 1E
In the above embodiment, the coil spring 53 is described as an example of the biasing member, but the spring used for the biasing member is not limited to the coil spring 53. Further, although a spring such as a coil spring 53 has been described as an example of the biasing member, the biasing member is not limited to a spring, and another elastic member such as rubber can be used as the biasing member. Also, for example, a magnet can be used as the biasing member. The repulsive force or attractive force generated between the magnet and the magnet can be used as a biasing force, or the attractive force generated between the magnet and the metal can be used as a biasing force.

(4-6) Modified Example 1F
In the embodiment and the modification 1A, when the differential pressure deviates from the predetermined pressure range set for the differential pressure type expansion valve 33, the number of revolutions of the outdoor fan 34 serving as a radiator fan in the refrigeration apparatus 10 exclusively for cooling. Of the differential pressure type expansion valve 33 by changing the differential pressure toward a predetermined pressure range by adjusting the rotational speed of the outdoor fan 34 which is a fan for the evaporator, in the refrigeration system 10A for heating only. The case of changing the valve opening has been described as an example.

However, in the refrigeration system 10 exclusively for cooling, by adjusting the rotation speed of the indoor fan 22 which is a fan for the evaporator, and in the refrigeration system 10A exclusively for heating, the rotation speed of the indoor fan 22 which is a radiator fan is adjusted. Thus, the differential pressure may be changed toward a predetermined pressure range to change the valve opening degree of the differential pressure type expansion valve 33. Further, the differential pressure is changed toward a predetermined pressure range by adjusting the rotational speeds of both the outdoor fan 34 and the indoor fan 22 which are the fan for the radiator and the fan for the evaporator in the refrigerating

apparatus

10, 10A, and the differential pressure type expansion You may comprise so that the valve-opening degree of the valve 33 may be changed.

(4-7) Modified Example 1G
In the above embodiment and the above modification, the refrigeration apparatus 10 can be operated in an appropriate refrigeration cycle, for example, the refrigerant sucked by the compressor 31 does not become a liquid refrigerant by controlling the discharge superheat degree to fall within an appropriate range. I am in control. However, the refrigeration system to which the concept of the above embodiment can be applied is not limited to the refrigeration system 10 that performs the control as described above, and controls, for example, the suction superheat degree of the compressor 31 within an appropriate range. Thus, the concept of the above-described embodiment can be applied to a system in which the refrigeration system is operated in an appropriate refrigeration cycle such that the refrigerant sucked by the compressor 31 does not become a liquid refrigerant.

(4-8) Modified Example 1H
In the above embodiment and the above modification, the difference is achieved by adjusting the number of rotations of the radiator fan and / or the evaporator fan to return to the predetermined pressure range both when it deviates from the upper limit and the lower limit of the predetermined pressure range. Although the pressure is changed toward the predetermined pressure range to change the valve opening degree of the differential pressure type expansion valve, the predetermined pressure only when it deviates from the upper limit of the predetermined pressure range or only when it deviates from the lower limit By adjusting the rotational speed of the radiator fan and / or the evaporator fan to return to the range, the differential pressure is changed toward the predetermined pressure range to change the valve opening degree of the differential pressure type expansion valve. It is also good.

(4-9) Modified Example 1I
The current value of the compressor 31 may be used to estimate whether the differential pressure of the differential pressure type expansion valve 33 deviates from the predetermined pressure range. For example, when the refrigeration system 10 is operated while the discharge superheat degree is controlled to be a predetermined value or less during the cooling operation, the superheat degree is too high such that the discharge superheat degree is higher than the predetermined value think of. The degree of discharge superheat is determined, for example, by subtracting the detection value (condensing temperature) of the outdoor heat exchanger temperature sensor 37 from the detection value (discharge temperature) of the discharge temperature sensor 35.

When the outdoor temperature is low and the indoor temperature is high, if the discharge superheat degree is too high, the control device 40 of the refrigeration system 10 performs control to increase the circulation amount of the refrigerant to lower the discharge superheat degree. Do. At this time, since the outdoor temperature is low and the condensation temperature is low, the condensation pressure is low, and since the outdoor temperature is high, the evaporation temperature is high and the evaporation pressure is also high, so the differential pressure of the differential pressure type expansion valve 33 is also small. As a result, the opening degree of the differential pressure type expansion valve 33 is reduced. In such a case, the degree of discharge superheat is also too high, and the control device 40 does not perform control to increase the number of revolutions of the compressor 31.

In such a case, in order to increase the circulation amount of the refrigerant, the control device 40 reduces the rotational speed of the outdoor fan 34 to raise the condensation temperature. When the condensation temperature rises, the condensation pressure rises and the differential pressure of the differential pressure type expansion valve 33 becomes large. When the differential pressure of the differential pressure type expansion valve 33 becomes large, the differential pressure type expansion valve 33 can be opened to increase the circulation amount of the refrigerant.

When performing such control, the control device 40 monitors the current value of the compressor 31. Therefore, the control device 40 has a function of detecting the current value of the compressor 31. If the differential pressure of the differential pressure type expansion valve 33 is too small, the circulation amount of the refrigerant is also small, so the current value of the compressor 31 also becomes small. Therefore, the control device 40 can estimate the differential pressure of the differential pressure type expansion valve 33 from the current value of the compressor 31. The control device 40 can estimate the differential pressure from the current value of the compressor 31 and can perform control to reduce the rotational speed of the outdoor fan 34 in a state where the degree of discharge superheat is too high. In this case, the controller 40 does not estimate the differential pressure of the differential pressure type expansion valve 33 from the current value of the compressor 31, but the controller 40 determines that the discharge superheat degree is too high and the current value of the compressor 31 is predetermined. When the condition that the current value is smaller is satisfied, it may be determined to decrease the rotation speed of the outdoor fan 34 directly, and control may be performed to reduce the rotation speed of the outdoor fan 34. In other words, the control device 40 may directly determine that the differential pressure of the differential pressure type expansion valve 33 has deviated from the predetermined pressure range using the current value of the compressor 31.

In the above description, although the discharge superheat degree is described, for example, also in the case where the refrigeration apparatus 10 is operated while the suction superheat degree is controlled to be a predetermined value or less during the cooling operation, as described above. Control using the current value of the compressor 31 can be performed. The degree of suction superheat is determined by subtracting the evaporation temperature from the suction temperature of the compressor 31. In order to perform such control, for example, a suction temperature sensor for detecting the suction temperature of the compressor 31 is provided, and the control device 40 detects the detection value of the indoor heat exchanger temperature sensor 24 from the detection value of the suction temperature sensor A calculation function is provided which subtracts the evaporation temperature).

(4-10) Modified Example 1J
Although the above-mentioned embodiment and modification explained the case where indoor fan 22 and outdoor fan 34 can adjust number of rotations, indoor fan 22 and outdoor fan 34 switch only ON and OFF without adjusting number of rotations. May be of the type that can

For example, changing the air volume of the outdoor fan 34 to a smaller value includes the case where the outdoor fan 34 is turned off, and changing the air volume of the indoor fan 22 so as to reduce the air volume. Is included. Further, in the case where a plurality of outdoor fans 34 are provided, reducing the number of outdoor fans 34 that are on is included in the case where the air volume is changed to be smaller. This is included when changing the number to increase the air volume. Similarly, in the case where a plurality of indoor fans 22 are provided, reducing the number of indoor fans 22 being turned on is included when changing the air volume to be smaller, and the indoor fans 22 being turned on are included. In the case of changing to increase the air volume, it is included in the case of increasing the number of.

For example, when the outdoor temperature is low and the indoor temperature is high, if the discharge superheat degree is too high, the control device 40 of the refrigeration system 10 increases the circulation amount of the refrigerant to lower the discharge superheat degree. Take control. In such a case, the controller 40 turns off the outdoor fan 34 to increase the condensation temperature in order to increase the circulating amount of the refrigerant. When performing such control, for example, the control device 40 is a differential pressure type expansion valve from the condensation temperature (the detection value of the outdoor heat exchanger temperature sensor 37) and the evaporation temperature (the detection value of the indoor heat exchanger temperature sensor 24). 33 differential pressures can be estimated. The control device 40 can estimate the differential pressure from the condensation temperature and the evaporation temperature, and can perform control to turn off the outdoor fan 34 in a state where the degree of discharge superheat is too high. In this case, the controller 40 does not estimate the differential pressure of the differential pressure type expansion valve 33 from the condensation temperature and the evaporation temperature, but the controller 40 determines that the discharge superheat degree is too high and the temperature difference between the condensation temperature and the evaporation temperature If the condition that the difference is smaller than the predetermined temperature difference is satisfied, it may be determined that the outdoor fan 34 is to be turned off directly, and the control to turn off the outdoor fan 34 may be performed. In other words, the control device 40 may directly determine that the differential pressure of the differential pressure type expansion valve 33 deviates from the predetermined pressure range using the temperature difference between the condensing temperature and the evaporation temperature.

(4-11) Modified Example 1K
In the above embodiment, the case where the control device 40 performs control by interpreting and executing executable program data stored in the memory by the CPU has been described. The program data may be introduced into the memory via the recording medium, or may be executed directly from the recording medium. Further, the introduction of data from the recording medium to the memory may be performed via a telephone line, a transport path, or the like. However, the control device 40 may be configured using an integrated circuit (IC) that can perform the same control as that performed using the CPU and the memory. Here, the IC includes a large-scale integrated circuit (LSI), an application-specific integrated circuit (ASIC), a gate array, a field programmable gate array (FPGA), and the like.

(5) Characteristics (5-1)
As described in the above embodiment, modification 1A and modification 1F, in the

refrigeration apparatuses

10 and 10A, the differential pressure between the refrigerant inlet 61 and the refrigerant outlet 62 of the differential pressure type expansion valve 33 deviates from the predetermined pressure range SC At the same time, the differential pressure is changed toward the predetermined pressure range SC by adjusting the number of rotations of the radiator fan and / or the evaporator fan and changing the air volume of the radiator fan and / or the evaporator fan. Since the valve opening degree of the pressure type expansion valve 33 is changed, it is prevented that the differential pressure deviates from the predetermined pressure range SC and the differential pressure becomes too large or too small. As a result, in the

refrigeration apparatuses

10 and 10A, problems caused by the degree of superheat of the refrigerant related to the compressor 31 becoming larger than the appropriate value or the degree of superheat becoming smaller than the appropriate value are suppressed.

In the refrigeration apparatus 10, the outdoor heat exchanger 32 functions as a radiator (or condenser), the indoor heat exchanger 21 functions as an evaporator, the outdoor fan 34 functions as a radiator fan, and the indoor fan 22 functions as a fan for the evaporator. Further, in the refrigeration system 10A, the outdoor heat exchanger 32 functions as an evaporator, the indoor heat exchanger 21 functions as a radiator, the outdoor fan 34 functions as an evaporator fan, and the indoor fan 22 is a radiator fan Acts as.

For example, in the refrigeration apparatus 10, when the differential pressure exceeds the upper limit value of the predetermined pressure range SC, the rotational speed of the outdoor fan 34 is increased to increase the air volume, and when the differential pressure falls below the lower limit value of the predetermined pressure range SC Since the number of rotations of the outdoor fan 34 is reduced to reduce the air volume, the number of rotations of the outdoor fan 34 is reduced to lower the heat exchange efficiency in the outdoor heat exchanger 32 which is a radiator and deviate from the predetermined pressure range SC. When this occurs, the differential pressure can be changed toward the predetermined pressure range SC.

(5-2)
Since the differential pressure is controlled to be within the predetermined pressure range SC by adjusting the rotational speed of the outdoor fan 34 which is a radiator fan, the refrigeration apparatus 10 is a fan for an evaporator without being bound by the adjustment of the differential pressure. The rotation speed of the indoor fan 22 can be controlled. By performing control such that the differential pressure does not deviate from the predetermined pressure range SC, it is possible to prevent the air conditioning of the room which is the air conditioning target space by the indoor fan 22 which is the evaporator fan from being restricted.

In the refrigeration apparatus 10A, when the differential pressure is controlled to be within the predetermined pressure range SC by adjusting the rotational speed of the outdoor fan 34, which is a fan for the evaporator, it is not bound by the adjustment of the differential pressure. The number of rotations of the indoor fan 22, which is a radiator fan, can be controlled. In this case, by performing control such that the differential pressure does not deviate from the predetermined pressure range SC, it is possible to prevent the air conditioning of the room which is the air conditioning target space by the indoor fan 22 from being restricted.

(5-3)
In the above-described

refrigeration systems

10 and 10A, the outdoor heat exchanger 32 and the indoor heat exchanger 21 which are radiators and evaporators are installed indoors, one of which is a space to be air conditioned, and the other is outdoor, the heat source side space. The indoor temperature sensor 23 which is installed and is provided in order to detect the indoor temperature which is space temperature of air-conditioning object space is provided. The refrigeration apparatuses 10 and 10A are adjustment of the rotational speed of the outdoor fan 34 blowing air outside, and are detected using at least the indoor temperature sensor 23 for adjustment for changing the differential pressure toward the predetermined pressure range. The room temperature is used. Thereby, the valve opening degree of the differential pressure type expansion valve 33 can be made larger or smaller in accordance with the situation where the room temperature is high or low. For example, in the refrigeration apparatus 10, the rotation speed of the outdoor fan 34 is adjusted using at least the room temperature, the room temperature is high, the refrigerant is easily evaporated in the evaporator, and the room temperature is low. The valve opening degree of the differential pressure type expansion valve 33 can be made larger or smaller in accordance with the occurrence of the difficult situation. As a result, it is possible to suppress the valve opening degree from becoming too small or too large in the differential pressure type expansion valve 33 without affecting the air flow in the room and maintain an appropriate degree of superheat.

(5-4)
The above-described

refrigeration systems

10 and 10A include the outdoor temperature sensor 36, which is a second sensor provided to detect the outdoor temperature that is the ambient temperature of the heat source side space. The refrigeration apparatuses 10 and 10A are detected by using the indoor temperature sensor 23 and the outdoor temperature sensor 36 in adjustment for adjusting the rotational speed of the outdoor fan 34 and changing the differential pressure toward the predetermined pressure range SC. Temperature difference is used.

Such refrigeration apparatuses

10 and 10A perform adjustment for changing the differential pressure toward the predetermined pressure range SC based on the temperature difference between the indoor temperature and the outdoor temperature. Control can be performed according to the difference, and an appropriate degree of superheat can be maintained with high accuracy.

(5-5)
The

refrigeration apparatus

10, 10A according to the above-described embodiment is a temperature sensor 24 for an indoor heat exchanger, which is a third sensor provided in the

refrigerant circuit

11, 11A to detect the condensation temperature of the radiator and the evaporation temperature of the evaporator. And a pair of outdoor heat exchanger temperature sensors 37. At least the temperature sensor 24 for indoor heat exchangers and the temperature sensor for outdoor heat exchangers for adjusting the rotational speed of the outdoor fan 34 and / or the indoor fan 22 to change the differential pressure of the differential pressure type expansion valve 33 toward the predetermined pressure range SC. Since the condensation temperature and the evaporation temperature detected using 37 are used, the valve opening degree of the differential pressure type expansion valve 33 is made large according to the situation where the difference between the high pressure value and the low pressure value of the refrigeration cycle is small or large. Since the differential pressure type expansion valve 33 can be made smaller or smaller, it is possible to maintain an appropriate degree of superheat by suppressing the valve opening degree from becoming too small or too large. For example, in the refrigeration apparatus 10, the refrigerant is easily evaporated in the indoor heat exchanger 21 which is an evaporator, and the difference between the high pressure value and the low pressure value of the refrigeration cycle is large and the refrigerant is hardly evaporated in the indoor heat exchanger 21. The degree of opening of the differential pressure type expansion valve can be increased or decreased according to the occurrence.

(5-6)
The above-described

refrigeration apparatus

10, 10A includes a discharge temperature sensor 35 which is a fourth sensor provided in the

refrigerant circuit

11, 11A to detect the discharge temperature of the refrigerant discharged from the compressor 31. Since the discharge temperature detected using at least the discharge temperature sensor 35 is used to adjust the rotational speed of the outdoor fan 34 and / or the indoor fan 22 to change the differential pressure toward the predetermined pressure range SC, the discharge temperature is The valve opening degree of the differential pressure type expansion valve 33 can be made large even before the safety mechanism works. As a result, in the differential pressure type expansion valve 33, it is possible to maintain an appropriate degree of superheat while preventing the safety mechanism from working due to the valve opening becoming too small.

(5-7)
One of the indoor heat exchanger 21 and the outdoor heat exchanger 32, which are the evaporator and the radiator, is installed in the room which is the air conditioning target space, and the other is installed in the outdoor where the heat source side space is installed. And an outdoor temperature sensor 36, which is a second sensor provided to detect the outdoor temperature which is the ambient temperature of the heat source side space. Then, the

refrigeration apparatuses

10 and 10A further adjust the number of rotations of the outdoor fan 34 based on the number of rotations of the compressor 31 and the outdoor temperature detected using the outdoor temperature sensor 36. For example, the refrigeration apparatus 10 adjusts the number of rotations of the outdoor fan 34 based on the number of rotations of the compressor 31 and the outdoor temperature during normal operation. Since the adjustment is performed based on the rotation speed of the compressor 31 and the outdoor temperature, the rotation speed of the outdoor fan 34 can be appropriately adjusted even within the predetermined pressure range SC.

(5-8)
The differential pressure type expansion valve 33 of the

refrigeration system

10, 10A has a main body 51 and a valve body 52, and the main body 51 is a coil spring 53 which is a biasing member supporting the refrigerant inlet 61, the refrigerant outlet 62 and the valve body 52. have. In the differential pressure type expansion valve 33, static friction for maintaining the positional relationship between the valve body 52 and the main body 51 against the biasing force of the coil spring 53 is generated between the valve body 52 and the main body 51. The valve body 52 is disposed between the refrigerant inlet 61 and the refrigerant outlet 62 and moves to change the valve opening degree by the differential pressure exceeding the limit pressure which keeps the stationary state without moving. The change of the differential pressure toward the predetermined pressure range SC by adjusting the rotation speed of the outdoor fan 34 and / or the indoor fan 22 is a change exceeding the limit pressure.

(5-9)
In the case where the control device 40 directly determines that the differential pressure has deviated from the predetermined pressure range using at least one of the room temperature, the outside temperature, the condensation temperature, the evaporation temperature, the discharge temperature, and the current value of the compressor, The control device 40 can omit the process of estimating the differential pressure. Further, according to such a refrigeration apparatus 10, the control device 40 estimates the differential pressure using at least one of the indoor temperature, the outdoor temperature, the condensation temperature, the evaporation temperature, the discharge temperature, and the current value of the compressor. In the case of determination, accurate control can be facilitated along the differential pressure. The following control may be performed by performing a simulation or a test on a real machine in advance and obtaining data. For example, in a cooling operation, in a situation where the evaporation temperature does not change much, it may be determined whether the air volume of the outdoor fan 34 is to be reduced by estimating the differential pressure directly or from the condensation temperature. Conversely, for example, in a cooling operation, in a situation where the condensation temperature does not change much, it is determined whether to reduce the air volume of the outdoor fan 34 directly or by estimating the differential pressure from the evaporation temperature and performing control Good. For example, in the cooling operation, when the outdoor air is taken into the room for ventilation and the indoor temperature becomes the same as the outdoor temperature, the air volume of the outdoor fan 34 is estimated directly or from the differential pressure estimated from the change in the indoor temperature. It may be determined whether or not to reduce. For example, when the outdoor temperature suddenly falls in the evening at the time of cooling operation, it is determined whether the air volume of the outdoor fan 34 is to be reduced directly or by estimating the differential pressure according to the change in the outdoor temperature. You may go. For example, in a cooling operation, in a situation where the discharge temperature changes abnormally when the differential pressure is small, it is judged whether the air volume of the outdoor fan 34 is to be reduced directly or by estimating the differential pressure from the discharge temperature. You may With regard to the current value of the compressor 31, as described in the modification 1I, it is determined whether the air volume of the outdoor fan 34 is to be reduced directly or by estimating the differential pressure from the current value of the compressor 31 and performing control. May be The air volume may be controlled directly or by estimating the differential pressure using the room temperature, the outdoor temperature, the condensation temperature, the evaporation temperature, the discharge temperature, and the current value of the compressor alone, but some of these may be used. Alternatively, the air volume may be controlled by directly or by estimating a differential pressure.

(5-10)
When the differential pressure of the differential pressure type expansion valve 33 is too small during the cooling operation, the refrigeration apparatus 10 is in a state where a sufficient refrigerant flow rate can not be obtained because the valve opening degree of the differential pressure type expansion valve 33 is too small. If the flow rate is not sufficient and the degree of superheat is too high, it is difficult to increase the number of revolutions of the compressor 31. Even in such a state, the refrigeration apparatus 10 is a simple control in which the control device 40 stops the outdoor fan 34, and the refrigerant in the gas-liquid two-phase state passes through the outdoor heat exchanger 32 functioning as a radiator. Temperature (condensing temperature) can be raised. Thereby, the differential pressure of the differential pressure type expansion valve 33 is increased to increase the valve opening degree of the differential pressure type expansion valve 33, and the flow rate of the refrigerant is increased, so that the state of the superheat degree can be easily eliminated. .

While the embodiments of the present disclosure have been described above, it will be understood that various changes in form and detail can be made without departing from the spirit and scope of the present disclosure as set forth in the claims. .

10,

10A Refrigerating Apparatus

11, 11A Refrigerant Circuit 20 Utilization Unit 21 Indoor Heat Exchanger (Example of Evaporator or Example of Radiator)
22 Indoor fan (example of an evaporator fan or example of a radiator fan)
23 Indoor temperature sensor (example of first sensor)
24 Temperature sensor for indoor heat exchanger (constitutes third sensor with temperature sensor 37 for outdoor heat exchanger)
30 heat source unit 31 compressor 32 outdoor heat exchanger (example of a radiator or example of an evaporator)
33 Differential pressure type expansion valve 34 Outdoor fan (example of fan for radiator or example of fan for evaporator)
35 Discharge temperature sensor (example of the 4th sensor)
36 Outdoor temperature sensor (example of second sensor)
37 Temperature sensor for outdoor heat exchanger (constitutes the third sensor with the temperature sensor 24 for indoor heat exchanger)
43 timer 51 main body 52 valve body 53 coil spring (example of biasing member)

JP 2004-218918 A

Claims

Compressor fan (31), radiator (32, 21), differential pressure type expansion valve (33), evaporator (21, 32), fan for radiator (34, 22) that generates an air flow in the radiator And an evaporator fan (22, 34) for generating an air flow in the evaporator;
The refrigerant circulates in the order of the compressor, the radiator, the differential pressure type expansion valve, and the evaporator, and the refrigerant is changed according to the valve opening degree which changes according to the differential pressure between the refrigerant inlet and the refrigerant outlet of the differential pressure type expansion valve. A refrigerant circuit (11, 11A) whose flow rate changes is configured,
When the differential pressure deviates from the predetermined pressure range, the differential pressure is changed toward the predetermined pressure range by changing the air volume of the radiator fan and / or the evaporator fan to change the differential pressure type expansion valve. A refrigeration system that changes the degree of valve opening.
The change of the air volume of the radiator fan and / or the evaporator fan is performed by adjusting the number of rotations of the radiator fan and / or the evaporator fan.
The refrigeration apparatus according to claim 1.
The predetermined pressure range is changed based on the number of revolutions of the compressor.
The freezing apparatus of Claim 1 or Claim 2.
The evaporator (21) is installed in an air conditioning target space,
Changing the air volume of the radiator fan (34) so that the differential pressure falls within the predetermined pressure range;
The refrigeration apparatus according to any one of claims 1 to 3.
One of the radiator and the evaporator is installed in the air conditioning target space, and the other is installed in the heat source side space,
It further comprises a first sensor (23) provided to detect the space temperature of the air conditioning target space,
It is a change of the air volume of one of the fan for the radiator and the fan for the evaporator which blows in the heat source side space, and at least the change of the air volume for changing the differential pressure toward the predetermined pressure range. Using the space temperature detected using a first sensor,
The refrigeration apparatus according to any one of claims 1 to 3.
It further comprises a second sensor (36) provided for detecting the ambient temperature of the heat source side space,
It is a change of the air volume of one of the fan for the radiator and the fan for the evaporator which blows in the heat source side space, and the air volume change for changing the differential pressure toward the predetermined pressure range Using a temperature difference detected using one sensor and the second sensor,
The refrigeration apparatus according to claim 5.
The system further comprises a third sensor (24, 37) provided in the refrigerant circuit to detect the condensation temperature of the radiator and the evaporation temperature of the evaporator.
The condensing temperature and the evaporation temperature detected by using at least the third sensor for changing the air flow rate of the radiator fan and / or the evaporator fan for changing the differential pressure toward the predetermined pressure range Using
The refrigeration apparatus according to any one of claims 1 to 4.
And a fourth sensor (35) provided in the refrigerant circuit to detect the discharge temperature of the refrigerant discharged from the compressor.
The discharge temperature detected using at least the fourth sensor is used to change the air volume of the radiator fan and / or the evaporator fan for changing the differential pressure toward the predetermined pressure range.
The refrigeration apparatus according to any one of claims 1 to 4.
One of the radiator and the evaporator is installed in the air conditioning target space, and the other is installed in the heat source side space,
It further comprises a second sensor (36) provided for detecting the ambient temperature of the heat source side space,
The air volume of one of the fan for the radiator and the fan for the evaporator, which is blown to the heat source side space, and the number of revolutions of the compressor and the ambient temperature detected using the second sensor. change,
The refrigeration apparatus according to any one of claims 1 to 4.
The differential pressure type expansion valve has a main body (51) and a valve body (52),
The main body has the refrigerant inlet, the refrigerant outlet, and a biasing member (53) for supporting the valve body.
In the differential pressure type expansion valve, a static friction for maintaining the positional relationship between the valve body and the main body against the biasing force of the biasing member is generated between the valve body and the main body,
The valve body is disposed between the refrigerant inlet and the refrigerant outlet and moves to change the valve opening degree by changing the differential pressure exceeding the limit pressure for keeping the stationary state without moving.
The change in the differential pressure toward the predetermined pressure range by changing the air volume of the radiator fan and / or the evaporator fan is a change exceeding the limit pressure.
The refrigeration apparatus according to any one of claims 1 to 9.
When the differential pressure exceeds the upper limit of the predetermined pressure range, the air volume of the radiator fan is increased, and when the differential pressure is lower than the lower limit of the predetermined pressure range, the air volume of the radiator fan is decreased. Do,
The refrigeration apparatus according to any one of claims 1 to 10.
And a controller (40) for controlling the compressor, the radiator fan, and the evaporator fan.
One of the radiator and the evaporator is installed in the air conditioning target space, and the other is installed in the heat source side space,
The controller determines that the differential pressure has deviated from the predetermined pressure range, the space temperature of the air conditioning target space, the ambient temperature of the heat source side space, the condensation temperature, the evaporation temperature, the discharge temperature, and the current value of the compressor Directly, or at least one of the space temperature, the atmosphere temperature, the condensation temperature, the evaporation temperature, the discharge temperature, and the current value of the compressor to estimate the differential pressure. If it is determined that the differential pressure is deviated from the predetermined pressure range, the air flow of the radiator fan and / or the evaporator fan is changed so as to change the differential pressure toward the predetermined pressure range. Are configured to be able to control
The refrigeration apparatus according to any one of claims 1 to 3.
When the differential pressure is out of the predetermined pressure range, the differential pressure is too small during the cooling operation, and the differential pressure is too small, and the degree of superheat of the refrigerant sucked or discharged by the compressor exceeds a predetermined value. If the degree of superheat is too high,
Changing the differential pressure toward the predetermined pressure range by changing the air volume of the radiator fan increases the differential pressure by stopping the radiator fan and returns the pressure within the predetermined pressure range. Including
The refrigeration apparatus according to any one of claims 1 to 12.