JPH11294904A - Lubricant discharge control device of refrigeration cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of lubricant to be discharged from a compressor during a refrigeration cycle, by providing a first valve mechanism part at piping from the compressor to a condenser and a second valve mechanism part at piping from an evaporator to the compressor, and closing the first and second valve mechanism parts when the compressor is stopped. SOLUTION: Opening/closing valves 11 and 12 are provided at piping from a compressor 1 to an indoor heat exchanger 3 and from an indoor heat exchanger 5 to the compressor 1, respectively. Then, a valve mechanism control means 10 for opening/closing the valve mechanism of the opening/closing valves 11 and 12 is provided. When the compressor 1 is to be stopped, the opening/ closing valves 11 and 12 are closed by the valve mechanism control means 10. At this time, first, the opening/closing valve 12 is blocked, then the compressor 1 is stopped at a timing for preventing the compressor 1 from being overloaded, and at the same time the opening/closing valve 11 is blocked most preferably, thus reducing the amount of refrigerant in the compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigeration system using an HC-based refrigerant such as propane or isobutane as a refrigerant, and using, as a lubricating oil in the compressor, no or no mutual solubility with the refrigerant. The present invention relates to a cycle lubricating oil return device.

[0002]

2. Description of the Related Art R2 currently used in a refrigeration cycle
It is said that the HCFC-based refrigerant represented by No. 2 destroys the ozone layer due to the stability of its physical properties. In recent years,
HFC-based refrigerants have begun to be used as substitutes for HCFC-based refrigerants, but these HFC-based refrigerants have properties that promote the warming phenomenon. Therefore, recently, the use of an HC-based refrigerant that does not significantly affect the destruction of the ozone layer and the global warming phenomenon has begun to be studied. However, since this HC-based refrigerant is a flammable refrigerant, it is necessary to prevent explosion and ignition beforehand and to ensure safety. As one method for ensuring this safety, there is a method of reducing the amount of refrigerant used. In other words, flammable refrigerants do not ignite or explode unless they reach a certain concentration in the air,
By reducing the amount of the charged refrigerant, ignition and explosion can be prevented beforehand, and the probability of danger can be significantly reduced. Also,
Reducing the amount of refrigerant used leads to effective use of resources. By the way, in order to reduce the amount of refrigerant enclosed in the refrigeration cycle, it is effective to use a lubricating oil having low mutual solubility with the refrigerant and to reduce the amount of refrigerant dissolved in the lubricating oil.

[0003]

However, when the lubricating oil having low mutual solubility with the refrigerant is discharged from the compressor together with the refrigerant, the lubricating oil circulates in the refrigeration cycle in a state separated from the refrigerant. It stays inside and has poor return characteristics to the compressor. If the return amount of the lubricating oil to the compressor is small, the lubricating oil in the compressor runs short, and poor lubrication occurs in sliding parts such as a compression mechanism. In particular, HC
Unlike HCFC-based refrigerants and CFC-based refrigerants, system-based refrigerants do not have lubricity by themselves, so lack of lubricating oil in the compressor is a major problem. Therefore, in order to use a lubricating oil having low mutual solubility with respect to the HC-based refrigerant, the problem of lubricating oil shortage must be solved. In order to solve the problem of insufficient lubricating oil, it is important to reduce the amount of lubricating oil discharged from the compressor. In particular, it has been found that a large amount of lubricating oil is discharged due to foaming caused by the presence of the liquid refrigerant generated when the compressor is started.

Accordingly, the present invention solves the problem of insufficient lubricating oil in the compressor by reducing the amount of lubricating oil discharged from the compressor during the refrigeration cycle, and reduces lubricating oil having low mutual solubility with refrigerant. An object of the present invention is to realize the use of oil and to reduce the amount of refrigerant to be sealed in a refrigeration cycle.
In particular, an object of the present invention is to reduce the amount of refrigerant present in the compressor when the compressor is stopped, thereby preventing the foaming phenomenon at the time of starting the compressor and reducing the discharge amount of lubricating oil generated at the time of starting. I do.

[0005]

According to a first aspect of the present invention, there is provided a refrigeration cycle lubricating oil discharge control device comprising a compressor, a condenser, a throttle device, and an evaporator connected in a ring through pipes. In the above, using an HC-based refrigerant as a refrigerant, using a lubricating oil incompatible with or less soluble in the HC-based refrigerant as a lubricating oil in the compressor, a first valve in a pipe from the compressor to the condenser A mechanism section is provided with a second valve mechanism section in a pipe from the evaporator to the compressor, and a valve mechanism control means for closing the first and second valve mechanism sections when the compressor is stopped is provided. It is characterized by having. The lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 2 is a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via respective pipes. An HC-based refrigerant is used as a refrigerant, and a lubricating oil incompatible with or less soluble in the HC-based refrigerant is used as a lubricating oil in the compressor, and a first oil is provided in a pipe from a discharge port of the compressor to the four-way valve. A second valve mechanism is provided in the pipe from the four-way valve to the suction port of the compressor, and the first and second valve mechanisms are closed when the compressor is stopped. A valve mechanism control means is provided. A lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 3, wherein the compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes. HC-based refrigerant is used as a refrigerant, and lubricating oil incompatible with or less soluble in HC-based refrigerant is used as lubricating oil in the compressor, and the compression is performed in a pipe from a discharge port of the compressor to the four-way valve. A check valve for preventing the flow of refrigerant in the direction of the compressor, an on-off valve provided in a pipe from the four-way valve to the suction port of the compressor, and a valve mechanism for closing the on-off valve when the compressor is stopped A control means is provided. The lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 4, wherein the compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring via pipes, respectively. HC-based refrigerant is used as a refrigerant, and lubricating oil incompatible with or less soluble in HC-based refrigerant is used as lubricating oil in the compressor, and the compression is performed in a pipe from a discharge port of the compressor to the four-way valve. A check valve for preventing the flow of refrigerant in the machine direction, an on-off valve provided in the pipe from the outdoor heat exchanger to the four-way valve,
When the compressor is stopped, the four-way valve is connected to the heating operation mode, and valve mechanism control means for closing the on-off valve is provided. The lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 5 is a compressor,
In a refrigeration cycle in which a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes, an HC-based refrigerant is used as a refrigerant, and a non-phase with the HC-based refrigerant as lubricating oil in the compressor. Using a lubricating oil having low solubility or mutual solubility, a check valve for preventing the flow of the refrigerant in the direction from the compressor toward the compressor in a pipe from the discharge port of the compressor to the four-way valve; An on-off valve is provided in the pipe to the heat exchanger, and when the compressor is stopped, the four-way valve is set to the connection state of the cooling operation mode and valve mechanism control means for closing the on-off valve is provided. I do. The lubricating oil discharge control device for a refrigeration cycle of the present invention according to claim 6 is a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via piping. HC-based refrigerant is used as a refrigerant, and lubricating oil incompatible with or less soluble in HC-based refrigerant is used as lubricating oil in the compressor, and the compression is performed in a pipe from a discharge port of the compressor to the four-way valve. A check valve for preventing the flow of refrigerant in the machine direction is provided, and when stopping the compressor, the four-way valve connects the suction side pipe of the compressor to either the indoor heat exchanger or the outdoor heat exchanger. A valve mechanism control means for establishing a connection state that does not communicate with the pipe is provided. The lubricating oil discharge control device for a refrigeration cycle of the present invention according to claim 7 is a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring via piping. HC-based refrigerant is used as the refrigerant, lubricating oil incompatible with the HC-based refrigerant or having low mutual solubility is used as the lubricating oil in the compressor, and the four-way valve suctions the compressor when the compressor is stopped. A valve mechanism control means is provided for setting the side pipe and the discharge side pipe to a connection state that does not communicate with any of the pipes of the indoor heat exchanger and the outdoor heat exchanger. According to an eighth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to any one of the first to sixth aspects, a judging means for judging an overheating state in the compressor is provided. The stop is performed after the determination unit determines that the overheating state is present. According to a ninth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the eighth aspect, the determination unit performs the determination by detecting a pressure and a temperature in the compressor. According to a tenth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the eighth aspect, a high-pressure compressor is used as the compressor, and a discharge pressure and a discharge temperature of the compressor are determined by the determination means. It is characterized by using. The invention according to claim 11 is
The lubricating oil discharge control device for a refrigeration cycle according to claim 8, wherein a high-pressure compressor is used as the compressor, and a condensing temperature of the condenser and a discharge temperature of the compressor are used for the determination unit. I do. According to a twelfth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the eighth aspect, a low-pressure compressor is used as the compressor, and a suction pressure and a suction temperature of the compressor are determined by the determination means. It is characterized by using. According to a thirteenth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the eighth aspect, a low-pressure compressor is used as the compressor, and the evaporation temperature of the evaporator and the suction temperature of the compressor are adjusted. It is characterized in that it is used for the determination means. According to a fourteenth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the eighth aspect, a high-pressure compressor is used as the compressor, and the suction temperature and the suction pressure of the compressor are determined by the determination means. It is characterized by using. According to a fifteenth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the fourteenth aspect, the condensation temperature of the condenser is used for the determination means. According to a sixteenth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the eighth aspect, an evaporating temperature of the evaporator and a condensing temperature of the condenser are used for the determination means. The invention according to claim 17 is
The lubricating oil discharge control device for a refrigeration cycle according to any one of claims 11 to 16, wherein the operating frequency of the compressor is used for the determination means. The present invention according to claim 18 is the lubricating oil discharge control device for a refrigeration cycle according to claim 8, wherein the evaporator uses a variable speed compressor as the compressor and a variable expansion valve as the throttle device. The evaporating temperature of the condenser, the condensing temperature of the condenser, the operating frequency of the compressor, and the valve opening of the expansion device are used for the determination means. According to a nineteenth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the eighth aspect, when the determination unit determines that the compressor is not in an overheated state, the controller determines whether the overheated state is present before stopping the compressor. The present invention is characterized in that an overheating control means for performing such control is provided. According to a twentieth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the nineteenth aspect, the overheating control means increases the rotation speed of the compressor. According to a twenty-first aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the nineteenth aspect, the superheat control means increases a rotation speed of a condenser fan provided in the condenser. And According to a twenty-second aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the nineteenth aspect, the superheat control means increases the rotation speed of an evaporator fan provided in the evaporator. And According to a twenty-third aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the nineteenth aspect, the superheat control means reduces an opening degree of the expansion device. According to a twenty-fourth aspect of the present invention, in the lubrication oil discharge control device for a refrigeration cycle according to the nineteenth aspect, a control valve is provided on a liquid-side pipe in the refrigeration cycle, and the overheating control means opens the control valve. It is characterized in that the degree is reduced. According to a twenty-fifth aspect of the present invention, in the lubrication oil discharge control device for a refrigeration cycle according to the nineteenth aspect, the superheat control means stops a compressor cooling device that cools the compressor. According to a twenty-sixth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the nineteenth aspect, the overheating control means operates a heater for heating the compressor. Claim 27
According to the present invention, there is provided the lubricating oil discharge control device for a refrigeration cycle according to claim 19, further comprising a display unit for indicating an operation state of the overheat control unit. Claim 2
According to an eighth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the nineteenth aspect, the superheat control means controls a rotation speed of an evaporator fan provided in the evaporator during a heating operation.
During the cooling operation, the rotation speed of the condenser fan provided in the condenser is increased. The present invention according to claim 29, in the lubricating oil discharge control device for a refrigeration cycle according to any one of claims 1 to 28, wherein propane or isobutane is used as the HC-based refrigerant, and a carbonate compound is used as the lubricating oil. It is characterized by using. According to a thirty-fourth aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to the thirty-ninth aspect, the lubricating oil has a structure in which the number of carbon atoms constituting the carbonate bond is the total number of carbon atoms constituting the carbonate compound. It is characterized by occupying 10 atomic% or more. According to a thirty-first aspect of the present invention, in the lubricating oil discharge control device for a refrigeration cycle according to any one of the first to thirty aspects, the mutual solubility between the HC-based refrigerant and the lubricating oil is 5 wt% or less. There is a feature. 33. The lubricating oil discharge control device for a refrigeration cycle according to the present invention, wherein the compressor, the condenser, the expansion device, and the evaporator are connected to each other in a ring via pipes. A first valve mechanism in the pipe to the second valve mechanism in the pipe from the evaporator to the compressor, the first and second valve mechanism when the compressor is stopped A valve mechanism control means for closing the valve is provided. The lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 33, wherein the compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring via pipes. A first valve mechanism is provided in a pipe from a discharge port of the compressor to the four-way valve, and a second valve mechanism is provided in a pipe from the four-way valve to a suction port of the compressor. And a valve mechanism control means for closing the first and second valve mechanism portions when stopping the operation. A lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 34, wherein the compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes. A check valve for preventing the flow of refrigerant in the direction of the compressor is provided in a pipe from a discharge port of the compressor to the four-way valve, and an on-off valve is provided in a pipe from the outdoor heat exchanger to the four-way valve. A valve mechanism control means for closing the on-off valve while setting the four-way valve in the heating operation mode when the compressor is stopped is provided. The lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 35, wherein the compressor, the four-way valve, the indoor heat exchanger, the expansion device, and the outdoor heat exchanger are connected in a ring via pipes. A check valve for preventing the flow of refrigerant in the direction of the compressor is provided in a pipe from a discharge port of the compressor to the four-way valve, and an on-off valve is provided in a pipe from the four-way valve to the indoor heat exchanger. A valve mechanism control means for closing the on-off valve while setting the four-way valve in the cooling operation mode when the compressor is stopped is provided. The lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 36, wherein a compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes. A check valve for preventing the flow of refrigerant in the direction of the compressor is provided in a pipe from a discharge port of the compressor to the four-way valve, and suction of the compressor is performed by the four-way valve when the compressor is stopped. A valve mechanism control means is provided for setting the side pipe to a connection state that does not communicate with any of the pipes of the indoor heat exchanger and the outdoor heat exchanger. A lubricating oil discharge control device for a refrigeration cycle according to the present invention according to claim 37, wherein the compressor, the four-way valve, the indoor heat exchanger, the expansion device, and the outdoor heat exchanger are connected in a ring via pipes.
A valve mechanism control for connecting the suction side pipe and the discharge side pipe of the compressor by the four-way valve so as not to communicate with any of the indoor heat exchanger and the outdoor heat exchanger when the compressor is stopped. Means are provided.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first to seventh embodiments of the present invention, when the compressor is stopped, the compressor is shut off from another refrigeration cycle such as a condenser or an evaporator, and the compressor is stopped in the refrigeration cycle. It is possible to minimize and prevent the refrigerant that enters into the compressor and stays as a liquid refrigerant. That is, during the operation of the refrigeration cycle, the refrigerant in the superheated state often stays in the compressor, and the refrigerant density is lower than the liquid region in the refrigeration cycle, but when the operation is stopped, the refrigeration cycle is in an equilibrium state. As a result, the refrigerant enters the compressor. Especially when the compressor is in a stopped state for a long time, the compressor has a larger heat capacity than a condenser or an evaporator, so even if the outside air temperature decreases at night and the outside air temperature increases during the day, the temperature of the compressor can be easily increased. Without rising
Since the temperature is the lowest in the refrigeration cycle, the refrigerant enters. The refrigerant that has entered in this manner becomes a liquid state and stays. Therefore, the first to sixth aspects of the present invention
In the embodiment, the refrigerant is prevented from entering the compressor, thereby preventing foaming at the time of starting the compressor and preventing the lubricant from being discharged from the compressor due to foaming.

A first embodiment of the present invention is directed to a first valve mechanism provided between a compressor and a condenser and a second valve mechanism provided between a compressor and an evaporator. Are closed when the compressor is stopped.

In a second embodiment of the present invention, a first valve mechanism is provided in a pipe from a compressor discharge port to a four-way valve, and a second valve mechanism is provided in a pipe from a four-way valve to a compressor suction port. The first and second valve mechanisms are closed when the compressor is stopped. According to the present embodiment, in any of the cooling and heating operation modes, when the compressor is stopped, the compressor is shut off from another refrigeration cycle such as a condenser or an evaporator,
It is possible to prevent the refrigerant present in the refrigeration cycle from entering the compressor and staying as a liquid refrigerant.

According to a third embodiment of the present invention, a check valve is provided in a pipe from a discharge port of a compressor to a four-way valve, and an open / close valve is provided in a pipe from a four-way valve to a suction port of the compressor. When the compressor is stopped, the on-off valve is closed. By using a check valve on the discharge side of the compressor in this manner, pressure loss due to the valve mechanism is reduced, and a valve drive device is not required.

In a fourth embodiment of the present invention, a check valve is provided in a pipe from a discharge port of a compressor to a four-way valve, and an on-off valve is provided in a pipe from an outdoor heat exchanger to a four-way valve. When the machine is stopped, the four-way valve is connected to the heating operation mode and the on-off valve is closed. Generally, a pipe with a large diameter is used as a pipe on the suction side of the compressor to reduce pressure loss. That is, since the pipe from the outdoor heat exchanger to the four-way valve uses a small-diameter pipe compared to the pipe on the compressor suction side from the four-way valve, it is more preferable to provide an on-off valve in this small-diameter pipe. A small on-off valve can be used, and the size of the device can be reduced. In the present embodiment, it is necessary to change the connection state of the four-way valve during the cooling operation, but it is not necessary to change the connection state of the four-way valve during the heating operation.

According to a fifth embodiment of the present invention, a check valve is provided in a pipe from a compressor discharge port to a four-way valve, and an on-off valve is provided in a pipe from a four-way valve to an indoor heat exchanger. When the machine is stopped, the four-way valve is connected to the cooling operation mode and the on-off valve is closed. Generally, even in this case, the pipe from the indoor heat exchanger to the four-way valve uses a smaller diameter pipe than the pipe from the four-way valve to the compressor suction side. Providing this can use a smaller on-off valve, and can reduce the size of the device. In the present embodiment, it is necessary to change the connection state of the four-way valve during the heating operation, but it is not necessary to change the connection state of the four-way valve during the cooling operation.

According to a sixth embodiment of the present invention, a check valve is provided in a pipe from a discharge port of a compressor to a four-way valve, and when the compressor is stopped, a suction-side pipe of the compressor is connected by the four-way valve. This is a connection state that does not communicate with any of the pipes of the indoor heat exchanger and the outdoor heat exchanger. As described above, in the present embodiment, the check valve is used on the discharge side of the compressor, and the four-way valve is used on the suction side. By using a four-way valve in this way, there is no need to add a new valve, and the pressure loss can be reduced at low cost.

According to a seventh embodiment of the present invention, when the compressor is stopped, the four-way valve connects the suction side pipe and the discharge side pipe of the compressor to both the indoor heat exchanger and the outdoor heat exchanger. This is a connection state in which communication is not established. As described above, the present embodiment utilizes a four-way valve without separately providing a check valve or an on-off valve. By using a four-way valve in this way, there is no need to add a new valve, and the pressure loss can be reduced at low cost.

In an eighth embodiment of the present invention, in the first to seventh embodiments, the compressor is stopped after judging the overheating state. By stopping the compressor in the overheated state as described above, the amount of refrigerant in the compressor at the time of stoppage can be further reduced.

A ninth embodiment of the present invention uses the pressure and temperature in the compressor for the judgment in the eighth embodiment. As described above, by directly detecting the inside of the compressor, it is possible to reliably determine the overheating state.

In a tenth embodiment of the present invention, when a high-pressure compressor is used in the eighth embodiment, the discharge pressure and the discharge temperature of the compressor are used for determination.
According to the present embodiment, the overheating state is directly detected, so that the overheating state can be reliably determined.

According to an eleventh embodiment of the present invention, when a high-pressure compressor is used in the eighth embodiment, the condensation temperature of the condenser and the discharge temperature of the compressor are used for determination. . According to the present embodiment, the determination can be made only by detecting the temperature without detecting the pressure, so that the determination can be easily performed by a detection unit that has been widely used conventionally.

In a twelfth embodiment of the present invention, when a low-pressure compressor is used in the eighth embodiment, the suction pressure and the suction temperature of the compressor are used for determination.
According to the present embodiment, it is possible to reliably determine the overheating state.

In the thirteenth embodiment of the present invention, when a low-pressure compressor is used in the eighth embodiment, the evaporation temperature of the evaporator and the suction temperature of the compressor are used for determination. . According to the present embodiment, the determination can be made only by detecting the temperature without detecting the pressure, so that the determination can be easily performed by a detection unit that has been widely used conventionally.

According to a fourteenth embodiment of the present invention, a high-pressure compressor is used as the compressor in the eighth embodiment,
The suction temperature and the suction pressure of the compressor are used for the determination means. According to the present embodiment, it is possible to detect an overheated state of the discharge by detecting that the suction state is an overheated state or a degree of dryness equal to or more than a predetermined value.

In a fifteenth embodiment of the present invention, the condensing temperature of the condenser in the fourteenth embodiment is further used as a judging means. According to the present embodiment, the detection accuracy can be further improved.

The sixteenth embodiment of the present invention uses the evaporating temperature of the evaporator and the condensing temperature of the condenser in the eighth embodiment as the judgment means. According to the present embodiment, since determination can be made only by temperature detection without pressure detection,
The determination can be easily performed by a detection means that has been widely used conventionally.

The seventeenth embodiment of the present invention uses the operating frequency of the compressor for the determination in the eleventh to sixteenth embodiments. According to the present embodiment, a pressure loss from the evaporation temperature can be considered according to the frequency, and a more reliable overheating state can be determined.

An eighteenth embodiment of the present invention is the same as the eighth embodiment, except that a variable-speed compressor is used as the compressor and a variable expansion valve is used as the expansion device. The condensing temperature of the compressor, the operating frequency of the compressor, and the valve opening of the expansion device are used as determination means. According to the present embodiment, the pressure loss from the evaporating temperature can be considered according to the frequency and the valve opening, and a more reliable overheating state can be determined.

In a nineteenth embodiment of the present invention, in the eighth embodiment, control is performed such that the compressor is overheated before the compressor is stopped. According to the present embodiment, even when the operation is not overheated when the operation is stopped, the compressor is stopped after being overheated, so that the amount of refrigerant in the compressor can be further reduced.

The twentieth embodiment of the present invention is different from the nineteenth embodiment in that the rotation speed of the compressor is increased. According to the present embodiment, since the amount of circulating refrigerant is increased, the amount of throttling is relatively increased, and an overheated state can be achieved.

The twenty-first embodiment of the present invention differs from the nineteenth embodiment in that the rotation speed of the condenser fan is increased. According to the present embodiment, the evaporation capacity is also increased because the condensation capacity is increased, and the state of the suction refrigerant can be changed to a state of higher dryness or a state of higher heating. In particular, in the case of a high-pressure compressor, the degree of heating of the suction refrigerant can be increased, so that the state of the refrigerant on the discharge side can be made overheated.

The twenty-second embodiment of the present invention differs from the nineteenth embodiment in that the rotation speed of the evaporator fan is increased. According to the present embodiment, the degree of superheating of the suction is increased due to an increase in the evaporation capacity, and the discharge side can be brought into an overheated state.

The twenty-third embodiment of the present invention differs from the nineteenth embodiment in that the opening of the aperture device is reduced. According to the present embodiment, since the throttle amount is large, the overheating state can be achieved.

In the twenty-fourth embodiment of the present invention, the opening degree of the control valve provided on the liquid side pipe in the refrigeration cycle in the nineteenth embodiment is reduced. According to the present embodiment, since the throttle amount is large, the overheating state can be achieved. In particular, when a capillary tube is used in the throttle device, the control valve can increase the throttle amount.

According to a twenty-fifth embodiment of the present invention, in the nineteenth embodiment, the compressor cooling device for cooling the compressor is stopped. According to the present embodiment, since the temperature of the compressor can be increased, the temperature of the refrigerant in the compressor shell can be increased to bring the compressor into an overheated state.

In a twenty-sixth embodiment of the present invention, a heater for heating a compressor is operated in the nineteenth embodiment. According to the present embodiment, since the temperature of the compressor can be increased, the temperature of the refrigerant in the compressor shell can be increased to bring the compressor into an overheated state.

The twenty-seventh embodiment of the present invention is different from the nineteenth embodiment in that a display means for indicating the operation state of the overheat control means is provided. According to the present embodiment, the fact that the overheat control operation is being performed is displayed, so that even if the device operates after the user issues a driving instruction, the user can be notified that there is no malfunction.

According to a twenty-eighth embodiment of the present invention, in the nineteenth embodiment, overheating is controlled by an evaporator fan during a heating operation and by a condenser fan during a cooling operation. According to the present embodiment, since the overheat control operation is always performed by the outdoor fan during both the heating operation and the cooling operation, it is possible to prevent the user from feeling uncomfortable or not being judged to be malfunctioning. .

It is effective to use propane or isobutane as such an HC-based refrigerant. As the lubricating oil, it is effective to use a carbonate compound. In particular, a lubricating oil in which the number of carbon atoms constituting a carbonate bond structurally accounts for 10 atom% or more of the total number of carbon atoms constituting a carbonate compound is preferable. Further, the mutual solubility between the HC-based refrigerant and the lubricating oil is preferably 5 wt% or less.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lubricating oil discharge control device for a refrigeration cycle according to one embodiment of the present invention will be described below with reference to the drawings. FIG.
FIG. 8 to FIG. 8 show an embodiment relating to the control means of the valve mechanism when stopping the compressor. FIG. 1 is a refrigeration cycle diagram for explaining the first embodiment. As shown in the figure, the compressor 1, the four-way valve 2, the indoor heat exchanger 3, the expansion device 4, and the outdoor heat exchanger 5 are connected in a ring shape through respective pipes. Here, the indoor heat exchanger 3 includes an indoor heat exchanger fan 6.
However, the outdoor heat exchanger 5 is provided with an outdoor heat exchanger fan 7. The indoor heat exchanger 3 functions as a condenser during the heating operation, and functions as an evaporator during the cooling operation. The outdoor heat exchanger 5 functions as an evaporator during the heating operation and functions as a condenser during the cooling operation. Accordingly, the indoor heat exchanger fan 6 functions as a condenser fan during the heating operation and as an evaporator fan during the cooling operation, and the outdoor heat exchanger fan 7 functions as an evaporator fan during the heating operation and as a condenser fan during the cooling operation. In this embodiment, as shown in the figure, an on-off valve 11 is provided in a pipe from the compressor 1 to the indoor heat exchanger 3, and an on-off valve 12 is provided in a pipe from the outdoor heat exchanger 5 to the compressor 1. ing. Further, a valve mechanism control means 10 for opening and closing the valve mechanism of the on-off valve 11 and the on-off valve 12 is provided.

The refrigerant used in the above refrigeration cycle is HC containing propane or isobutane as a main component.
Use a system flammable refrigerant. The lubricating oil in the compressor 1 has a higher specific gravity than the refrigerant liquid of the HC-based refrigerant,
Use a lubricating oil that is incompatible with the system refrigerant or has low mutual solubility. As such a lubricating oil, one composed of a carbonate compound is effective, and more preferably, one in which the number of carbon atoms constituting a carbonate bond structurally accounts for 10 atomic% or more of the total number of carbon atoms constituting a carbonate compound. Mutual solubility between HC-based refrigerant and lubricating oil is 5 wt% at 25 ° C.
% Is preferred.

In such a refrigeration cycle, during the heating operation, the refrigerant compressed by the compressor 1 is guided to the indoor heat exchanger 3 to radiate heat, decompressed by the expansion device 4 and transmitted to the outdoor heat exchanger 5. After the heat is absorbed, it is sucked into the compressor 1. In the cooling operation, the refrigerant compressed by the compressor 1 flows in the order of the outdoor heat exchanger 5, the expansion device 4, and the indoor heat exchanger 3, and is sucked into the compressor 1. When the compressor 1 is stopped, the on / off valves 11 and 12 are closed by the valve mechanism control means 10. At this time, the stop operation of the compressor 1 and the closing operation of the on-off valve 11 and the on-off valve 12 do not need to be performed at the same time. However, when the on-off valve 12 is closed before the compressor 1, if the time lag is too large, the compressor 1 is overloaded, which is not preferable. When the on-off valve 11 is closed before the compressor 1, it is preferable that the time lag be as small as possible because the refrigerant is accumulated in the compressor 1. When the on-off valve 11 and the on-off valve 12 are closed after the compressor 1 is stopped, it is preferable that the time lag is in seconds, but it is assumed that there is a time lag in minutes or extremely several hours. This also has the effect of preventing stagnation of the refrigerant. That is, the stagnation phenomenon of the refrigerant into the compressor is
This is because much occurs after the compressor 1 has cooled. It is most preferable to close the on-off valve 12 first, and then stop the compressor 1 and close the on-off valve 11 at a timing when the overload does not occur in the compressor 1. By closing the on-off valve 12 earlier than the on-off valve 11, the amount of refrigerant in the compressor 1 can be reduced.

FIG. 2 is a refrigeration cycle diagram for explaining the second embodiment. In the figure, components having the same functions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Further, the refrigerant and the lubricating oil used in the refrigeration cycle of the present embodiment are the same as those of the first embodiment, and therefore the description is omitted. The same applies to the following embodiments. In the present embodiment, as shown in the figure, a check valve 21 for preventing the flow of the refrigerant in the direction of the compressor 1 is provided in a pipe from the discharge port of the compressor 1 to the four-way valve 2 from the four-way valve 2. An on-off valve 22 is provided in a pipe leading to a suction port of the compressor 1. Open / close valve 22
A valve mechanism control means 20 for opening and closing the valve mechanism is provided.

When the compressor 1 is stopped, the on-off valve 22 is closed by the valve mechanism control means 20. At this time, the stop operation of the compressor 1 and the closing operation of the on-off valve 22 do not need to be performed at the same time, and either may be performed first if there is some time lag. However, when the on-off valve 22 is closed before the compressor 1, if the time lag is too large, the compressor 1 is overloaded, which is not preferable. When closing the on-off valve 22 after stopping the compressor 1,
The time lag is preferably in seconds, but even if there is a time lag in minutes or extremely several hours, there is an effect of preventing the refrigerant from falling asleep. It is most preferable that the on-off valve 22 be closed first, and then the compressor 1 be stopped at a timing at which no overload occurs in the compressor 1. By closing the on-off valve 22 before stopping the compressor 1 in this manner, the amount of refrigerant in the compressor 1 can be reduced.

FIG. 3 is a refrigeration cycle diagram for explaining the third embodiment. In this embodiment, as shown in the figure, the compressor 1 is provided in a pipe extending from the discharge port of the compressor 1 to the four-way valve 2.
A check valve 31 for preventing the flow of the refrigerant in the direction is provided, and an on-off valve 32 is provided in a pipe extending from the outdoor heat exchanger 5 to the four-way valve 2. Further, a valve mechanism control means 30 for controlling the valve mechanisms of the on-off valve 32 and the four-way valve 2 is provided.

When the compressor 1 is stopped, the four-way valve 2 is first set to the heating operation mode connection state by the valve mechanism control means 30 as shown in FIG. During the heating operation, the four-way valve 2 is already in such a connected state, so there is no need for valve control. After switching the connection state of the four-way valve 2, the on-off valve 32 is closed. At this time, the stopping operation of the compressor 1 and the closing operation of the on-off valve 32 do not need to be performed at the same time, and either may be performed first if a certain time lag occurs. However, when the on-off valve 32 is closed before the compressor 1, if the time lag is too large, the compressor 1 is overloaded, which is not preferable. When the on-off valve 32 is closed after the compressor 1 is stopped, the time lag is preferably in seconds, but even if there is a time lag in minutes or extremely several hours, the refrigerant may stagnate. There is an effect of prevention. It is most preferable that the on-off valve 32 be closed first, and then the compressor 1 be stopped at a timing at which no overload occurs in the compressor 1. By closing the on-off valve 32 before stopping the compressor 1 in this manner,
The amount of refrigerant in the compressor 1 can be reduced.

FIG. 4 is a refrigeration cycle diagram for explaining the fourth embodiment. In this embodiment, as shown in the figure, the compressor 1 is provided in a pipe extending from the discharge port of the compressor 1 to the four-way valve 2.
Check valve 41 for blocking the flow of refrigerant in the
An on-off valve 42 is provided in a pipe extending from the inside to the indoor heat exchanger 3. Further, a valve mechanism control means 40 for controlling the valve mechanisms of the on-off valve 42 and the four-way valve 2 is provided.

When the compressor 1 is stopped, the four-way valve 2 is first set to the cooling operation mode connection state by the valve mechanism control means 40 as shown in FIG. During the cooling operation, the four-way valve 2 is already in such a connected state, so there is no need for valve control. Then, after switching the connection state of the four-way valve 2, the on-off valve 42 is closed. At this time, the stop operation of the compressor 1 and the closing operation of the on-off valve 42 do not need to be performed at the same time, and either may be performed first if there is some time lag. However, when the on-off valve 42 is closed before the compressor 1, if the time lag is too large, the compressor 1 is overloaded, which is not preferable. When the on-off valve 42 is closed after the compressor 1 is stopped, it is preferable that the time lag is on the order of seconds, but even if there is a time lag on the order of minutes or extremely on the order of several hours, the refrigerant may stagnate. There is an effect of prevention. It is most preferable to first close the on-off valve 42 and then stop the compressor 1 at a timing at which no overload occurs on the compressor 1. By closing the on-off valve 42 before stopping the compressor 1 in this manner,
The amount of refrigerant in the compressor 1 can be reduced.

FIGS. 5 to 7 are refrigeration cycle diagrams for explaining the fifth embodiment. 5 shows a connection state in the heating operation mode, FIG. 6 shows a connection state in the cooling operation mode, and FIG. 7 shows a connection state in the operation stop mode. In this embodiment, as shown in the figure, a check valve 5 for preventing the flow of refrigerant in the direction of the compressor 1 is provided in a pipe extending from the discharge port of the compressor 1 to the four-way valve 200.
1 is provided. Further, a valve mechanism control means 50 for controlling the valve mechanism of the four-way valve 200 is provided. Here the four-way valve 200
The configuration will be briefly described. The four-way valve 200 includes a cylinder 210 and a piston 220 slidable in the cylinder 210. The description of the driving means of the piston 220 is omitted. In the cylinder 210,
A first port 211, a second port 212, a third port 213, and a fourth port 214 are provided in this order. First
A port communicating with the indoor heat exchanger 3 is connected to the port 211 of
The second port 212 has a pipe communicating with the discharge port of the compressor 1, the third port 213 has a pipe communicating with the outdoor heat exchanger 5, and the fourth port 214 has a suction port of the compressor 1. Connect the piping that communicates with. On the other hand, the piston 220 includes a first opening 221, a second opening 222, a third opening 223, a fourth opening 224, and a fifth opening 225 in this order.
It has. The first opening 221, the fourth opening 224, and the fifth opening 225 communicate with each other. Further, the second opening 222 and the third opening 223 communicate with each other.

Here, the flow of the refrigerant in the four-way valve 200 will be described. During the heating operation, as shown in FIG. 5, the first port 211 and the second opening 222, the second port 212 and the third opening 223, and the third port 21
The piston 220 is positioned such that the third and fourth openings 224 correspond to the fourth port 214 and the fifth opening 225. Therefore, the refrigerant discharged from the compressor 1 flows through the second port 212 and the third opening 223 to the piston 2.
20, the second opening 222, the first port 2
Outflow from 21. On the other hand, the refrigerant from the outdoor heat exchanger 5 flows into the piston 220 from the third port 213 and the fourth opening 224, and flows out from the fifth opening 225 and the fourth port 224. During the cooling operation, as shown in FIG. 6, the first port 211 and the first opening 221, the second port 212 and the second opening 222, the third port 213 and the third opening 223, The piston 220 is positioned such that the fourth port 214 and the fourth opening 224 correspond. Therefore, the refrigerant discharged from the compressor 1 flows into the piston 220 from the second port 212 and the second opening 222, and flows out from the third opening 223 and the third port 223. On the other hand, the refrigerant from the indoor heat exchanger 3 flows into the piston 220 from the first port 211 and the first opening 221, and flows into the fourth opening 224 and the fourth opening 224.
Out of the port 224. When the compressor 1 is stopped, the four-way valve 200 is turned by the valve mechanism control means 50 as shown in FIG.
Make the connection state shown in. That is, the first port 211
And the third opening 223, the second port 212 and the fourth opening 224, and the third port 213 and the fifth opening 225.
The piston 220 is arranged so as to correspond to the above. Therefore, the refrigerant discharged from the compressor 1 is supplied to the second port 21
2, flows into the piston 220 from the fourth opening 224, and flows out from the fifth opening 225 and the third port 223. On the other hand, the refrigerant from the indoor heat exchanger 3 flows into the piston 220 from the first port 211 and the third opening 223, but the second opening 222 does not communicate with any port. No refrigerant flows. Therefore, no refrigerant flows into the compressor 1. In the case of the present embodiment, the four-way valve 200 is switched by the valve mechanism control unit 50 after the compressor 1 is stopped.

FIG. 8 is a refrigeration cycle diagram for explaining the sixth embodiment. In the present embodiment, as shown in the figure, a valve mechanism control means 60 for controlling the valve mechanism of the four-way valve 2 is provided. Here, the four-way valve 2 can connect the suction-side pipe and the discharge-side pipe of the compressor 1 to a connection state that does not communicate with any of the indoor heat exchanger 3 and the outdoor heat exchanger 5. Also in the case of the present embodiment, the four-way valve 2 is switched by the valve mechanism control means 60 after the compressor 1 is stopped.

Next, a description will be given of an embodiment relating to a judging means for judging the overheating state of the compressor and an overheating control means for setting the overheating state with reference to FIG. Note that the configurations shown in FIGS. 1 to 8 described above are applied to the valve mechanism and the valve mechanism control means, and the display and description are omitted in FIG. In the figure, a judging means 8 judges an overheating state of the compressor 1, and an overheating control means 9 controls so as to be in an overheating state when the judging means 8 judges that the compressor 1 is not in an overheating state.

First, the first embodiment of the judging means 8 uses the pressure 81P and the temperature 81T in the compressor 1 for the judgment. Thus, the pressure 82P and the temperature 82 in the compressor 1
By directly detecting T, it is possible to reliably determine the overheating state. In the second embodiment of the judgment means 8, when a high-pressure compressor is used as the compressor 1, the discharge pressure 82P and the discharge temperature 82T of the compressor 1 are used for the judgment. According to this embodiment, the overheating state is directly detected, so that the overheating state can be reliably determined. Judgment means 8
In the third embodiment, when a high-pressure compressor is used as the compressor 1, the condensing temperature 83T of the indoor heat exchanger 3 and the discharge temperature 82T of the compressor 1 are used for determination during the heating operation, and during the cooling operation. Condensing temperature 85T of outdoor heat exchanger 5 and compressor 1
Is used for the determination. According to the present embodiment, since the determination can be made only by detecting the temperature, the determination can be easily performed. In addition, this condensation temperature 83T, 85T
Needs to detect the temperature of the gas-liquid two-phase state. Therefore, it is preferable that the detection be performed near the center of the indoor heat exchanger 3 and the outdoor heat exchanger 5. The fourth embodiment of the judging means 8 is such that when a low-pressure compressor is used as the compressor 1,
The suction pressure 84P and the suction temperature 84T are used for the determination. According to the present embodiment, it is possible to reliably determine the overheating state when a low-pressure compressor is used. The fifth embodiment of the judging means 8 uses the evaporation temperature 85T of the outdoor heat exchanger 5 and the suction temperature 84T of the compressor 1 during the heating operation when the low-pressure compressor is used as the compressor 1, During the cooling operation, the evaporation temperature 83T of the indoor heat exchanger 3 and the discharge temperature 82T of the compressor 1 are used for the determination. According to this embodiment, the determination can be made simply by detecting the temperature without detecting the pressure, so that the determination can be made easily. The evaporation temperature 83
For T and 85T, it is necessary to detect the temperature of the gas-liquid two-phase state. Therefore, it is preferable that the detection be performed near the center of the indoor heat exchanger 3 and the outdoor heat exchanger 5. The sixth embodiment of the judging means 8 is such that when a high-pressure compressor is used as the compressor 1,
The suction temperature 84T and the suction pressure 84P of the compressor 1 are used for the determination. According to the present embodiment, it is possible to detect an overheated state of the discharge by detecting that the suction state of the compressor 1 is an overheated state or a degree of dryness equal to or more than a predetermined value.

In the seventh embodiment of the judging means 8, the condensing temperature 83T of the indoor heat exchanger 3 during the heating operation and the condensing temperature 8 of the outdoor heat exchanger 5 during the cooling operation are determined in the sixth embodiment.
5T is further used. According to the present embodiment, the detection accuracy can be further improved.

In the eighth embodiment of the judging means 8, the condensing temperature 83T of the indoor heat exchanger 3 and the outdoor heat exchanger 5
Of the indoor heat exchanger 3 and the condensing temperature 85T of the outdoor heat exchanger 5 during the cooling operation. According to the present embodiment, since the determination can be made only by the temperature detection without detecting the pressure, it is possible to easily make the determination by a detection unit which has been widely used conventionally. This embodiment is particularly effective when the rotation speed of the compressor 1 is constant and the throttle amount of the expansion device 4 is fixed. However, the rotation speed of the compressor 1 is variable or Even when the amount is variable, the determination can be reliably performed by fixing the rotation speed and the throttle amount to a preset value at the time of the determination.

The ninth embodiment of the judging means 8 uses the operating frequency 86R of the compressor 1 for the judgment of the third to eighth embodiments. According to the present embodiment, a pressure loss from the evaporation temperature can be considered according to the frequency, and a more reliable overheating state can be determined. In this embodiment,
Although it is particularly effective when the aperture amount of the aperture device 4 is fixed, even when the aperture amount of the aperture device 4 is variable, the determination can be reliably performed by fixing the aperture amount set in advance at the time of determination. .

The tenth embodiment of the judging means 8 is the compressor 1
And a variable expansion valve as the expansion device 4. In the present embodiment, similarly to the eighth embodiment, the condensation temperature 8 of the indoor heat exchanger 3 during the heating operation is set.
3T and the evaporation temperature 85T of the outdoor heat exchanger 5, and the cooling temperature 83T and the evaporation temperature 83T of the indoor heat exchanger 3 during the cooling operation.
Is used for the determination, and the operating frequency 86R of the compressor 1 and the valve opening of the expansion device 4 are used for the determination. According to the present embodiment, the pressure loss from the evaporating temperature can be considered according to the frequency and the valve opening, and a more reliable overheating state can be determined. As the expansion device 4 in the present embodiment, there is a variable displacement type electric expansion valve.

The first embodiment of the overheating control means 9 is for increasing the rotation speed of the compressor 1. Arrow a in the figure is
2 shows a signal output to the compressor 1. At this time, the rotation speed of the compressor 1 is set and stored in advance. Note that the set number of rotations does not necessarily have to be one. It may have a plurality of set values according to the detected values. The number of rotations used during the heating operation and the number of rotations used during the cooling operation may be set in accordance with each operation cycle. Further, the rotation speed may be changed to a rotation speed that is faster than the current rotation speed by a certain amount, for example, instead of the preset rotation speed. It is most preferable that the time during which the operation is switched to the high-speed rotation is the time until the judging means 8 judges the overheating state. However, the time may be set in advance. Also in this case, the set time is not necessarily one. For example, a plurality of times may be set according to each operation cycle, such as a set time used in the heating operation and a set time used in the cooling operation. According to the present embodiment, since the amount of circulating refrigerant is increased, the amount of throttle is increased, and an overheated state can be achieved.

The second embodiment of the overheat control means 9 is to increase the rotation speed of the indoor heat exchanger fan 6 during the heating operation and the rotation speed of the outdoor heat exchanger fan 7 during the cooling operation. Arrow c in the figure indicates a signal output to the indoor heat exchanger fan 6, and arrow d in the figure indicates a signal output to the outdoor heat exchanger fan 7. At this time, the rotation speed of the condenser fan is set and stored in advance. Note that the set number of rotations does not necessarily have to be one. It may have a plurality of set values according to the detected values. Also, a plurality of rotation speeds may be set in accordance with each operation cycle, such as a rotation speed used in the heating operation and a rotation speed used in the cooling operation. Further, the rotation speed may be changed to a rotation speed that is faster than the current rotation speed by a certain amount, for example, instead of the preset rotation speed. It is most preferable that the time during which the operation is switched to the high-speed rotation is the time until the judging means 8 judges the overheating state. However, the time may be set in advance. Also in this case, the set time is not necessarily one. For example, a plurality of times may be set according to each operation cycle, such as a set time used in the heating operation and a set time used in the cooling operation. According to the present embodiment, since the condensing capacity is increased, the evaporating capacity is also increased, so that the suction state of the compressor can be overheated, so that both the high-pressure compressor and the low-pressure compressor can be overheated. .

The third embodiment of the overheat control means 9 is for increasing the rotation speed of the outdoor heat exchanger fan 7 during the heating operation and increasing the rotation speed of the indoor heat exchanger fan 6 during the cooling operation. At this time, the rotation speed of the evaporator fan is set and stored in advance. Note that the set number of rotations does not necessarily have to be one. It may have a plurality of set values according to the detected values. Also, a plurality of rotation speeds may be set in accordance with each operation cycle, such as a rotation speed used in the heating operation and a rotation speed used in the cooling operation. Further, the rotation speed may be changed to a rotation speed that is faster than the current rotation speed by a certain amount, for example, instead of the preset rotation speed. It is most preferable that the time during which the operation is switched to the high-speed rotation is the time until the judging means 8 judges the overheating state. However, the time may be set in advance.
Also in this case, the set time is not necessarily one. For example, a plurality of times may be set according to each operation cycle, such as a set time used in the heating operation and a set time used in the cooling operation. According to the present embodiment, the degree of superheating of the suction is increased due to an increase in the evaporation capacity, and the discharge side can be brought into an overheated state.

The fourth embodiment of the overheat control means 9 is to reduce the opening of the expansion device 4. Arrow d in the figure is
3 shows a signal output to the aperture device 4. The opening degree of the expansion device 4 is set and stored in advance. In addition,
The set value does not necessarily have to be one. It may have a plurality of set values according to the detected values. Further, a plurality of degrees may be set according to each operation cycle, such as an opening degree used during the heating operation and an opening degree used during the cooling operation. Further, the opening may not be a preset opening, but may be narrowed to an opening smaller than the current opening by, for example, a certain amount. It is most preferable that the time during which the operation is performed by switching the opening degree to a small value is the time until the determination means 8 determines the overheating state. However, the time may be set in advance. Also in this case, the set time is not necessarily one. For example, a plurality of times may be set according to each operation cycle, such as a set time used in the heating operation and a set time used in the cooling operation. According to the present embodiment,
Since the evaporation capability is increased, the degree of superheating of the suction is increased, and the discharge side can be brought into a superheated state. In the present embodiment, the opening degree of the expansion device 4 has been described. However, in the case where an expansion device having a constant expansion degree, such as a capillary tube, is used as the expansion device 4, as shown in FIG. , A control valve 94 may be provided, and control may be performed to reduce the valve opening of the control valve 94. Arrow e in the figure
Indicates a signal output to the control valve 94.

The fifth embodiment of the overheating control means 9 is to stop the compressor cooling device 95 for cooling the compressor 1. An arrow f in the figure indicates a signal output to the compressor cooling device 95. According to the present embodiment, since the temperature of the compressor 1 can be increased, the discharge temperature can be increased to bring the superheated state. Such a compressor cooling device 95 is usually used for a refrigerator or a large-sized compressor. The sixth embodiment of the overheat control means 9 operates a heater 96 for heating the compressor 1. An arrow g in the figure indicates a signal output to the heater 96. According to the present embodiment, since the temperature of the compressor can be increased, the discharge temperature can be increased, and the compressor can be overheated. The seventh embodiment of the overheat control means 9 performs overheat control by the outdoor heat exchanger fan 7 during both cooling and heating operations. According to the present embodiment, since the overheat control operation is always performed by the outdoor heat exchanger fan 7 both during the heating operation and the cooling operation, it is possible to prevent the user from feeling uncomfortable or to determine that a malfunction has occurred. be able to. As described above, since the superheat control means 9 performs control to bring the superheated state before the stop of the compressor 1, even if the superheat state is not at the time of stoppage of the operation, the superheat control means 9 stops the compressor after overheating.
The amount of refrigerant in the compressor can be further reduced.

FIG. 9 shows an embodiment of the flow when the compressor is stopped. First, an operation stop command is issued to the air conditioner by a remote control operation of a user or the like (step 1). When such an operation stop command is received, an overheating state is detected by the determination means as shown in step 2.
Here, if it is determined by the determining means that it is not in the overheat state, the overheat control operation is displayed in step 4 and the overheat control is performed in step 5. Then, if it is determined in step 3 that the overheating state has been reached, or if the overheating control has been completed in step 5, the valve mechanism is controlled and the compressor 1 is stopped in step 6 (step 7).

[0060]

The present invention solves the problem of insufficient lubricating oil in the compressor by reducing the amount of lubricating oil discharged from the compressor during the refrigeration cycle, and reduces the mutual solubility with the refrigerant. By using lubricating oil, it is possible to reduce the amount of refrigerant sealed in the refrigeration cycle. In particular, according to the present invention, by reducing the amount of refrigerant present in the compressor when the compressor is stopped, the foaming phenomenon at the time of starting the compressor can be prevented, and the discharge amount of lubricating oil generated at the time of starting can be reduced.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram according to a first embodiment relating to a control mechanism of a valve mechanism of the present invention.

FIG. 2 is a refrigeration cycle diagram according to a second embodiment relating to the control means of the valve mechanism of the present invention.

FIG. 3 is a refrigeration cycle diagram according to a third embodiment relating to the control means of the valve mechanism of the present invention.

FIG. 4 is a refrigeration cycle diagram according to a fourth embodiment relating to the control means of the valve mechanism of the present invention.

FIG. 5 is a refrigeration cycle diagram showing a heating operation mode according to a fifth embodiment relating to the control means of the valve mechanism of the present invention.

FIG. 6 is a refrigeration cycle diagram showing a cooling operation mode according to the embodiment.

FIG. 7 is a refrigeration cycle diagram showing an operation stop mode according to the embodiment.

FIG. 8 is a refrigeration cycle diagram according to a sixth embodiment relating to the control means of the valve mechanism of the present invention.

FIG. 9 is a refrigeration cycle diagram showing an embodiment relating to a judging means for judging an overheating state and an overheating control means of the present invention.

FIG. 10 is an operation flowchart according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Indoor heat exchanger 4 Throttle device 5 Outdoor heat exchanger 6 Indoor heat exchanger fan 7 Outdoor heat exchanger fan 8 Judgment means 9 Overheat control means 10 Valve mechanism control means 11 On-off valve 12 On-off valve 20 Valve mechanism control means 21 Check valve 22 Open / close valve 30 Valve mechanism control means 31 Check valve 32 Open / close valve 40 Valve mechanism control means 41 Check valve 42 Open / close valve 50 Valve mechanism control means 60 Valve mechanism control means 94 Control valve 95 Compression Machine cooling device 96 heater

 ──────────────────────────────────────────────────の Continued on the front page (72) Kanji Haneda 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Shigehiro Sato 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Shigeru 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (37)

[Claims] In a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are connected in a ring through pipes, an HC-based refrigerant is used as a refrigerant, and a HC-based refrigerant is used as a lubricating oil in the compressor. Using a lubricating oil having a low compatibility or mutual solubility, a first valve mechanism in the pipe from the compressor to the condenser, and a second valve mechanism in the pipe from the evaporator to the compressor. And a valve mechanism control means for closing the first and second valve mechanism portions when the compressor is stopped. 2. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger are connected in a ring through pipes, HC-based refrigerant is used as refrigerant, and lubrication in the compressor is performed. Using a lubricating oil having low compatibility or mutual solubility with the HC-based refrigerant as oil, a first valve mechanism in a pipe from a discharge port of the compressor to the four-way valve, Wherein a second valve mechanism is provided in the pipe to the suction port, and valve mechanism control means for closing the first and second valve mechanisms when the compressor is stopped is provided. Cycle lubrication oil discharge control device. 3. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes, HC-based refrigerant is used as refrigerant and lubrication in the compressor is performed. A check valve that uses a lubricating oil that is incompatible with or less soluble with the HC-based refrigerant as oil, and that blocks the flow of the refrigerant in the direction from the compressor to the pipe from the discharge port of the compressor to the four-way valve; A refrigeration cycle, characterized in that an on-off valve is provided in a pipe from the four-way valve to the suction port of the compressor, and valve mechanism control means for closing the on-off valve when the compressor is stopped is provided. Lubricating oil discharge control device. 4. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger are connected in a ring via pipes, HC-based refrigerant is used as refrigerant, and lubrication in the compressor is performed. A check valve that uses a lubricating oil that is incompatible with or less soluble with the HC-based refrigerant as oil, and that blocks the flow of the refrigerant in the direction from the compressor to the pipe from the discharge port of the compressor to the four-way valve; A valve mechanism control for providing an on-off valve in the pipe from the outdoor heat exchanger to the four-way valve, setting the four-way valve to the heating operation mode connection state and closing the on-off valve when the compressor is stopped A lubricating oil discharge control device for a refrigeration cycle, characterized by comprising means. 5. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes, HC-based refrigerant is used as refrigerant, and lubrication in the compressor is performed. A check valve that uses a lubricating oil that is incompatible with or less soluble with the HC-based refrigerant as oil, and that blocks the flow of the refrigerant in the direction from the compressor to the pipe from the discharge port of the compressor to the four-way valve; A valve mechanism control for providing an on-off valve in the pipe from the four-way valve to the indoor heat exchanger, setting the four-way valve to the cooling operation mode connection state and closing the on-off valve when the compressor is stopped A lubricating oil discharge control device for a refrigeration cycle, characterized by comprising means. 6. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes, HC-based refrigerant is used as refrigerant and lubrication in the compressor is performed. A check valve that uses a lubricating oil that is incompatible with or less soluble with the HC-based refrigerant as oil, and that blocks the flow of the refrigerant in the direction from the compressor to the pipe from the discharge port of the compressor to the four-way valve; And a valve mechanism control means for causing the four-way valve to connect the suction side pipe of the compressor to a connection state that does not communicate with any of the indoor heat exchanger and the outdoor heat exchanger when the compressor is stopped. A lubricating oil discharge control device for a refrigeration cycle, characterized in that it is provided. 7. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttle device, and an outdoor heat exchanger are connected in a ring via pipes, HC-based refrigerant is used as refrigerant and lubrication in the compressor is performed. When the compressor is stopped, the four-way valve uses the four-way valve to connect the suction side pipe and the discharge side pipe of the compressor to the indoor heat exchanger. A refrigeration cycle lubricating oil discharge control device provided with valve mechanism control means for establishing a connection state that does not communicate with any of the pipes of the outdoor heat exchanger. 8. The apparatus according to claim 1, further comprising a determination unit for determining a state of the refrigerant in the compressor, and stopping the compressor after determining that the compressor is in an overheated state. Item 8. The lubricating oil discharge control device for a refrigeration cycle according to any one of Items 7. 9. The lubricating oil discharge control device for a refrigeration cycle according to claim 8, wherein the determination means detects the pressure and temperature in the compressor. 10. The apparatus according to claim 8, wherein a high-pressure compressor is used as the compressor, and a discharge pressure and a discharge temperature of the compressor are used for the determination unit. . 11. The lubrication of a refrigeration cycle according to claim 8, wherein a high-pressure compressor is used as the compressor, and a condensing temperature of the condenser and a discharge temperature of the compressor are used for the determination means. Oil discharge control device. 12. The lubricating oil discharge control device for a refrigeration cycle according to claim 8, wherein a low-pressure compressor is used as the compressor, and a suction pressure and a suction temperature of the compressor are used for the determination means. . 13. The lubrication system according to claim 8, wherein a low-pressure compressor is used as the compressor, and an evaporating temperature of the evaporator and a suction temperature of the compressor are used for the determination unit. Oil discharge control device. 14. The apparatus according to claim 8, wherein a high-pressure compressor is used as the compressor, and a suction temperature and a suction pressure of the compressor are used for the determination means. . 15. The lubricating oil discharge control device for a refrigeration cycle according to claim 14, wherein the condensation temperature of the condenser is used for the determination means. 16. The lubricating oil discharge control device for a refrigeration cycle according to claim 8, wherein an evaporating temperature of the evaporator and a condensing temperature of the condenser are used for the determination means. 17. The compressor according to claim 11, wherein an operating frequency of said compressor is used for said determining means.
The lubricating oil discharge control device for a refrigeration cycle according to any one of the above. 18. A compressor having a variable number of revolutions as the compressor and a variable expansion valve as the expansion device, wherein an evaporating temperature of the evaporator, a condensing temperature of the condenser, an operating frequency of the compressor, and The lubricating oil discharge control device for a refrigeration cycle according to claim 8, wherein the valve opening degree of the expansion device is used for the determination unit. 19. The overheating control means for performing control to attain an overheating state before stopping the compressor when the determination means determines that the state is not an overheating state, is provided. Lubricating oil discharge control device for refrigeration cycle. 20. The lubricating oil discharge control device for a refrigeration cycle according to claim 19, wherein said superheat control means increases the rotation speed of said compressor. 21. The lubricating oil discharge control device for a refrigeration cycle according to claim 19, wherein the superheat control means increases a rotation speed of a condenser fan provided in the condenser. 22. The lubricating oil discharge control device for a refrigeration cycle according to claim 19, wherein the superheat control means increases the rotation speed of an evaporator fan provided in the evaporator. 23. The lubricating oil discharge control device for a refrigeration cycle according to claim 19, wherein said superheat control means reduces an opening degree of said expansion device. 24. The refrigeration cycle lubricating oil according to claim 19, wherein a control valve is provided in a liquid side pipe in the refrigeration cycle, and the overheating control means reduces an opening degree of the control valve. Discharge control device. 25. The lubricating oil discharge control device for a refrigeration cycle according to claim 19, wherein the superheat control means stops a compressor cooling device that cools the compressor. 26. The apparatus according to claim 19, wherein the overheating control means operates a heater for heating the compressor.
3. The lubricating oil discharge control device for a refrigeration cycle according to 1. 27. The lubricating oil discharge control device for a refrigeration cycle according to claim 19, further comprising display means for indicating an operation state of said overheat control means. 28. The superheat control means increases the rotation speed of the evaporator fan provided in the evaporator during the heating operation and increases the rotation speed of the condenser fan provided in the condenser during the cooling operation. The lubricating oil discharge control device for a refrigeration cycle according to claim 19. 29. The lubricating oil discharge control of the refrigeration cycle according to claim 1, wherein propane or isobutane is used as the HC-based refrigerant, and a carbonate compound is used as the lubricating oil. apparatus. 30. The lubrication of a refrigeration cycle according to claim 29, wherein the lubricating oil has a structure in which the number of carbon atoms constituting a carbonic acid ester bond accounts for at least 10 atomic% of the total number of carbon atoms constituting a carbonate compound. Oil discharge control device. 31. The mutual solubility of the HC-based refrigerant and the lubricating oil is 5% by weight or less.
31. The lubricating oil discharge control device for a refrigeration cycle according to claim 30. 32. In a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are connected in a ring through pipes, a first valve mechanism is provided in a pipe from the compressor to the condenser. A second valve mechanism is provided in a pipe from the evaporator to the compressor, and a valve mechanism control unit that closes the first and second valve mechanisms when the compressor is stopped is provided. Oil discharge control device for the refrigeration cycle. 33. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring through pipes, piping from a discharge port of the compressor to the four-way valve is provided. A first valve mechanism is provided therein, a second valve mechanism is provided in a pipe from the four-way valve to the suction port of the compressor, and the first and second valves are provided when the compressor is stopped. A lubrication oil discharge control device for a refrigeration cycle, comprising a valve mechanism control means for closing a mechanism. 34. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring via pipes, piping from a discharge port of the compressor to the four-way valve is provided. A check valve for preventing the flow of the refrigerant in the direction of the compressor therein, an on-off valve is provided in a pipe from the outdoor heat exchanger to the four-way valve, and the four-way valve is provided when the compressor is stopped. A lubricating oil discharge control device for a refrigeration cycle, comprising a valve mechanism control means for setting a connection state of a heating operation mode and closing the on-off valve. 35. A refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring via pipes, respectively, and a pipe from a discharge port of the compressor to the four-way valve. A check valve for preventing the flow of refrigerant in the direction of the compressor is provided therein, and an on-off valve is provided in a pipe from the four-way valve to the indoor heat exchanger, and the four-way valve is provided when the compressor is stopped. A lubricating oil discharge control device for a refrigeration cycle, comprising a valve mechanism control means for setting a connection state of a cooling operation mode and closing the on-off valve. 36. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring through pipes, piping from a discharge port of the compressor to the four-way valve is provided. A check valve for preventing the flow of the refrigerant in the direction of the compressor is provided therein, and when stopping the compressor, the four-way valve connects the suction side pipe of the compressor to the indoor heat exchanger and the outdoor heat exchange. A lubricating oil discharge control device for a refrigeration cycle, comprising a valve mechanism control means for establishing a connection state that does not communicate with any piping of the vessel. 37. In a refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger are connected in a ring via piping, when the compressor is stopped, the four-way valve is used. A refrigeration cycle lubrication system comprising a valve mechanism control means for connecting a suction side pipe and a discharge side pipe of the compressor to a connection state that does not communicate with any of the indoor heat exchanger and the outdoor heat exchanger. Oil discharge control device.