REFRIGERATION CYCLE EQUIPMENT

Technical Field

The present invention relates to refrigeration cycle equipment that is provided with a heat storage tank accommodating a heat storage material to store heat generated by a compressor and with a heat storage heat exchanger for heat exchanging with the heat storage material.

Background Art

A conventional heat pump air conditioner conducts defrosting during heating by switching a four-way valve from a heating cycle to a cooling cycle when frost has been formed on an outdoor heat exchanger. In this defrosting method, an indoor fan is at a stop, but cold air flows gradually out of an indoor unit, thus posing a problem of warmth being lost.

In view of this, another air conditioner has been proposed having a heat storage device mounted on a compressor in an outdoor unit for the purpose of defrosting by making use of waste heat of the compressor that has been stored in a heat storage tank during heating (see, for example,
Patent Document 1).

Fig. 9 depicts an example of refrigeration cycle equipment employing such a defrosting method. This refrigeration cycle equipment includes an outdoor unit, in which a compressor 100, a four-way valve 102, an outdoor heat exchanger 104, and a capillary tube 106 are provided, and an indoor unit in which an indoor heat exchanger 108 is provided.

All of the compressor 100, the four-way valve 102, the outdoor heat exchanger 104, the capillary tube 106, and the indoor heat exchanger 108 are connected via refrigerant piping.

The refrigeration cycle equipment also includes a first bypass circuit 110 for bypassing the capillary tube 106 and a second bypass circuit 112 having one end connected to a pipe extending from a discharge side of the compressor 100 to the indoor heat exchanger 108 via the four-way valve 102 and the other end connected to another pipe extending from the capillary tube 106 to the outdoor heat exchanger 104.

The first bypass circuit 110 includes a two-way valve 114, a check valve 116, and a heat storage heat exchanger 118, while the second bypass circuit 112 includes a two-way valve 120 and a check valve 122.

Furthermore, a heat storage tank 124 is provided around the compressor 100, and a heat storage material 126 for heat exchanging with the heat storage heat exchanger 118 is filled in the heat storage tank 124.

In this refrigeration cycle, the two two-way valves 114, 120 are opened during defrosting to allow part of a refrigerant discharged from the compressor 100 to flow into the second bypass circuit 112 and the remaining refrigerant to flow into the indoor heat exchanger 108 via the four-way valve 102. The refrigerant that has passed through the indoor heat exchanger 108 is used for heating, and a slight amount of the refrigerant then flows into the outdoor heat exchanger 104 via the capillary tube 106, while the remaining majority of the refrigerant flows into the first bypass circuit 110 and into the heat storage heat exchanger 118 via the two-way valve 114 to take heat from the heat storage material 126, and then passes through the check valve 116 to join the refrigerant that has passed through the capillary tube 106 before the refrigerant flows into the outdoor heat exchanger 104.

Thereafter, the refrigerant flowingtoward the outdoor heat exchanger 104 joins the refrigerant that has passed through the second bypass circuit 112 at an inlet of the outdoor heat exchanger 104 to conduct defrosting by making use of heat contained in the refrigerant.

After the defrosting, the refrigerant passes through the four-way valve 102 and then enters the compressor 100. In this refrigeration cycle, the second bypass circuit 112 acts to introduce a hot gas discharged from the compressor 100 during defrosting to the outdoor heat exchanger 104 and to maintain high the pressure of the refrigerant flowing into the outdoor heat exchanger 104, thus making it possible to enhance the defrosting capability and complete the defrosting within a considerably short period of time. Patent Document(s)

• Patent Document 1: No. JP 3-31666 A Summary of the Invention Problems to be solved by the Invention In the refrigeration cycle as disclosed in Patent Document 1, during the normal heating operation in which no defrosting is conducted, the two two-way valves 114, 120 are closed and the compressor 100 is operated. Accordingly, heat generated by the compressor 100 is stored in the heat storage material 126 and increases the temperature thereof.

Similarly, during the normal cooling operation, the two two-way valves 114, 120 are closed and the compressor 100 is operated. Accordingly, heat generated by the compressor 100 is stored in the heat storage material 126 and increases the temperature thereof.

However, an excessive temperature increase of the heat storage material 126 causes alteration (for example, oxidation) or water evaporation of the heat storage material 126, which in turn sometimes causes deterioration of the heat storage material 126.
The present invention has been developed to overcome the above-described disadvantage. It is accordingly an objective of the present invention to provide refrigeration cycle equipment capable of avoiding deterioration of a heat storage material that stores heat generated by a compressor.

Means to Solve the Problems In accomplishing the above objective, the present invention is directed to refrigeration cycle equipment having a compressor, an indoor heat exchanger, an expansion valve and an outdoor heat exchanger, all connected to one another via refrigerant piping, and also having a heat storage device.

The heat storage device includes a heat storage tank, a heat storage material accommodated in the heat storage tank to store heat generated by the compressor, and a heat storage heat exchanger for heat exchanging with the heat storage material.

A controller is provided to switch from a first air conditioning operation, in which a refrigerant discharged from the compressor passes, when a temperature of the heat storage material exceeds a predetermined temperature below a boiling point of water contained in the heat storage material, through the indoor heat exchanger, the expansion valve and the outdoor heat exchanger, to a second air conditioning operation in which the refrigerant discharged from the compressor passes, when a temperature of the heat storage material exceeds the predetermined temperature, through the heat storage heat exchanger.

The predetermined temperature is unambiguously determined in consideration of the boiling point of water irrespective of the heat storage material.

Effects of the Invention

According to the present invention, heat generated by the compressor is stored in the heat storage material accommodated within the heat storage device and when the temperature of the heat storage material exceeds the predetermined temperature, the controller switches to an operation in which the heat storage heat exchanger performs heat exchange by making use of heat storage in the heat storage material, followed by a reduction in temperature of the heat storage material.

Accordingly, an excessive temperature increase of and water evaporation in the heat storage material can be prevented, thus making it possible to avoid deterioration of the heat storage material.

Brief Description of the Drawings

Fig. 1 is a piping diagram of an air conditioner having a heat storage device according to the present invention.

Fig. 2 is a piping diagram of the air conditioner of Fig. 1, particularly depicting operation thereof and a flow of refrigerant during normal heating (first heating operation).

Fig. 3 is a piping diagram of the air conditioner of Fig. 1, particularly depicting operation thereof and a flow of refrigerant during defrosting/heating.

Fig. 4 is a piping diagram of the air conditioner of Fig. 1, particularly depicting operation thereof and a flow of refrigerant during a second heating operation.

Fig. 5 is a timing chart of a modification of a switching control for switching the first heating (cooling) operation and the second heating (cooling) operation, particularly depicting a switching operation of a solenoid valve provided on a refrigerant pipe that is branched from a refrigerant pipe for connecting an indoor heat exchanger and an expansion valve and leads to a heat storage heat exchanger.

Fig. 6 is an explanatory diagram in the case where the temperature of a heat storage material to open and close the solenoid valve differs at the time of rise and fall thereof.
Fig. 7 is a piping diagram of the air conditioner of Fig. 1, particularly depicting operation thereof and a flow of refrigerant during a normal cooling (first cooling) operation.

Fig. 8 is a piping diagram of the air conditioner of Fig. 1, particularly depicting operation thereof and a flow of refrigerant during a second cooling operation.

Fig. 9 is a piping diagram of conventional refrigeration cycle equipment. Embodiments for Carrying out the Invention The present invention is directed to refrigeration cycle equipment having a compressor, an indoor heat exchanger, an expansion valve and an outdoor heat exchanger, all connected to one another via refrigerant piping, and also having a heat storage device.

The heat storage device includes a heat storage tank, a heat storage material accommodated in the heat storage tank to store heat generated by the compressor, and a heat storage heat exchanger for heat exchanging with the heat storage material.

The refrigeration cycle equipment is provided with a controller to switch from a first air conditioning operation, in which a refrigerant discharged from the compressor passes, when a temperature of the heat storage material exceeds a predetermined temperature below a boiling point of water contained in the heat storage material, through the indoor heat exchanger, the expansion valve and the outdoor heat exchanger, to a second air conditioning operation in which the refrigerant discharged from the compressor passes, when a temperature of the heat storage material exceeds the predetermined temperature, through the heat storage heat exchanger.

The predetermined temperature is unambiguously determined in consideration of the boiling point of water irrespective of the heat storage material. According to the present invention, a first heating operation is switched to a second heating operation.

Heat generated by the compressor is stored in the heat storage material during the first heating operation, while the heat storage heat exchanger performs heat exchange by making use of heat storage in the heat storage material during the second heating operation, followed by a reduction in temperature of the heat storage material.

As such, an excessive temperature increase of and water evaporation in the heat storage material can be prevented, thus making it possible to avoid deterioration of the heat storage material.
Specifically, the refrigeration cycle equipment further includes a solenoid valve provided on a refrigerant pipe that is branched from another refrigerant pipe for connecting the indoor heat exchanger to the expansion valve and leads to the heat storage heat exchanger, the solenoid valve being opened and closed based on control signals from the controller, wherein the controller switches from the first heating operation to the second heating operation by opening the solenoid valve.

Preferably, the controller controls the solenoid valve to open the solenoid valve for a first predetermined time period in the second heating operation and then close the solenoid valve for a second predetermined time period. The second predetermined time period is typically longer than the first predetermined time period, thereby making it possible to maintain a desired heating operation using a relatively large solenoid valve.

When a sum of the first predetermined time period with the solenoid valve opened and the second predetermined time period with the solenoid valve closed is one cycle length, a switching control of the solenoid valve is repeated a predetermined number of cycles, thereby making it possible to reduce the temperature of the heat storage material down to a temperature at which deterioration of the heat storage material does not occur.

In another aspect of the present invention, a first cooling operation is switched to a second cooling operation. Heat generated by the compressor is stored in the heat storage material during the first cooling operation, while the heat storage heat exchanger performs heat exchange by making use of heat storage in the heat storage material during the second cooling operation, followed by a reduction in temperature of the heat storage material.

As such,an excessive temperature increase of and water evaporation in the heat storage material can be prevented, thus making it possible to avoid deterioration of the heat storage material.
Specifically, the refrigeration cycle equipment further includes a solenoid valve provided on a refrigerant pipe that is branched from another refrigerant pipe for connecting the indoor heat exchanger to the expansion valve and leads to the heat storage heat exchanger, the solenoid valve being opened and closed based on control signals from the controller, wherein the controller switches from the first cooling operation to the second cooling operation by opening the solenoid valve.

Preferably, the controller controls the solenoid valve to open the solenoid valve for a first predetermined time period in the second cooling operation and then close the solenoid valve for a second predetermined time period. The second predetermined time period is typically longer than the first predetermined time period, thereby making it possible to maintain a desired cooling operation using a relatively large solenoid valve.

When a sum of the first predetermined time period with the solenoid valve opened and the second predetermined time period with the solenoid valve closed is one cycle length, a switching control of the solenoid valve is repeated a predetermined number of cycles, thereby making it possible to reduce the temperature of the heat storage material down to a temperature at which deterioration of the heat storage material does not occur.

The refrigeration cycle equipment further includes, for example, a heat storage material temperature sensor operable to detect a temperature of the heat storage material, wherein the controller switches from the first heating operation to the second heating operation or from the first cooling operation to the second cooling operation based on the temperature detected by the heat storage material temperature sensor.

Another example of the refrigeration cycle equipment includes a compressor temperature sensor operable to detect a temperature of the compressor, wherein the controller switches from the first heating operation to the second heating operation or from the first cooling operation to the second cooling operation based on the temperature detected by the compressor temperature sensor.

A further example of the refrigeration cycle equipment includes a discharge refrigerant temperature sensor operable to detect a temperature of a refrigerant discharged from the compressor, wherein the controller switches from the first heating operation to the second heating operation or from the first cooling operation to the second cooling operation based on the temperature detected by the discharge refrigerant temperature sensor.

A still further example of the refrigeration cycle equipment includes a heat storage tank temperature sensor operable to detect a temperature of the heat storage tank, wherein the controller switches from the first heating operation to the second heating operation or from the first cooling operation to the second cooling operation based on the temperature detected by the heat storage tank temperature sensor.

A yet further example of the refrigeration cycle equipment includes a driving current sensor operable to detect a driving current of the compressor, wherein the controller switches from the first heating operation to the second heating operation or from the first cooling operation to the second cooling operation based on the driving current of the compressor detected by the driving current sensor.

It is preferred that a frequency of operation of the compressor be lower in the second heating operation than in the first heating operation. It is also preferred that the frequency of operation of the compressor be lower in the second cooling operation than in the first cooling operation.

When the aforementioned predetermined temperature is a first predetermined temperature and if the temperature of the heat storage material falls below a second predetermined temperature, which is lower than the first predetermined temperature, in the second heating operation, the controller preferably switches from the second heating operation to the first heating operation.

A temperature difference between the first predetermined temperature and the second predetermined temperature can prevent frequent repetition of the switching from the first heating operation to the second heating operation, and vice versa. Similarly, when the aforementioned predetermined temperature is a first predetermined temperature and if the temperature of the heat storage material falls below a second predetermined temperature, which is lower than the first predetermined temperature, in the second cooling operation, the controller preferably switches from the second cooling operation to the first cooling operation.

A temperature difference between the first predetermined temperature and the second predetermined temperature can prevent frequent repetition of the switching from the first cooling operation to the second cooling operation, and vice versa.

The refrigeration cycle equipment may further include a timer operable to measure a time period elapsed after the first heating operation has been switched to the second heating operation. In this case, if the time period measured by the timer reaches a predetermined time period in the second heating operation, the controller switches from the second heating operation to the first heating operation. Similarly, the refrigeration cycle equipment may include a timer operable to measure a time period elapsed after the first cooling operation has been switched to the second cooling operation. In this case, if the time period measured by the timer reaches a predetermined time period in the second cooling operation, the controller switches from the second cooling operation to the first cooling operation.

Embodiments of the present invention are explained hereinafter with reference to the drawings.
Fig. 1 depicts a piping diagram of an air conditioner that is refrigeration cycle equipment according to the present invention. The air conditioner includes an outdoor unit 2 and an indoor unit 4 connected to each other via refrigerant piping.

As shown in Fig. 1, the outdoor unit 2 accommodates therein a compressor 6, a four-way valve 8, a strainer 10, an expansion valve 12, and an outdoor heat exchanger 14, while the indoor unit 4 accommodates an indoor heat exchanger 16 therein. Those constituent elements are connected via refrigerant piping to define a refrigeration cycle.

More specifically, the compressor 6 and the indoor heat exchanger 16 are connected to each other via a first refrigerant pipe 18 to which the four-way valve 8 is fitted, and the indoor heat exchanger 16 and the expansion valve 12 are connected to each other via a second refrigerant pipe 20 to which the strainer 10 is fitted.

Also, the expansion valve 12 and the outdoor heat exchanger 14 are connected to each other via a third refrigerant pipe 22, and the outdoor heat exchanger 14 and the four-way valve 8 are connected to each other via a fourth refrigerant pipe 24.

The four-way valve 8 and a refrigerant suction side of the compressor 6 are connected to each other via an eighth refrigerant pipe 41. An accumulator 26 for separating a liquid phase refrigerant and a gas phase refrigerant is provided on the eighth refrigerant pipe 41 on the refrigerant suction side of the compressor 6. The compressor 6 and the third refrigerant pipe 22 are connected to each other via a fifth refrigerant pipe 28, on which a first solenoid valve 30 is provided.

Furthermore, a heat storage tank 32 accommodating a heat storage heat exchanger 34 therein is provided around the compressor 6 and filled with a heat storage material (for example, ethylene glycol aqueous solution) 36 for heat exchanging with the heat storage heat exchanger 34. The heat storage tank 32, the heat storage heat exchanger 34, and the heat storage material 36 constitute a heat storage device.

As well as the ethylene glycol aqueous solution, a glycol aqueous solution such as propylene glycol, a sodium chloride solution or the like may be used for the heat storage material 36.

In applications where a heat storage material 36 containing an aqueous solution as in the heat storage device 31 according to the present invention, it becomes necessary to avoid evaporation of water and, at the same time, to deal with an increase in pressure inside the heat storage tank 32 that is caused by steam. In view of this, the heat storage device according to the present invention is of an unsealed construction to alleviate the pressure increase and restrain, for example, the heat storage solution from reducing.

That is, the heat storage tank 32 has a vent hole defined in an upper portion thereof. Specifically, the heat storage tank 32 is provided with a rubber material having a pinhole that is employed as an internal pressure control means to cope with the pressure increase.

The rubber material is mounted to the upper portion of the heat storage tank 32 at a location held in contact with internal air. The vent hole has a small opening area to approximately close the heat storage tank 32, thereby making it possible to reduce the amount of evaporation of the heat storage material 36.

Also, the second refrigerant pipe 20 and the heat storage heat exchanger 34 are connected to each other via a sixth refrigerant pipe 38, and the heat storage heat exchanger 34 and the fourth refrigerant pipe 24 are connected to each other via a seventh refrigerant pipe 40. A second solenoid valve 42 is provided on the sixth refrigerant pipe 38.

The indoor unit 4 accommodates, in addition to the indoor heat exchanger 16, a fan (not shown), vertical wind direction changing blades (not shown), and horizontal wind direction changing blades (not shown).

The indoor heat exchanger 16 exchanges heat between indoor air sucked into the indoor unit 4 by the fan and a refrigerant flowing through the indoor heat exchanger 16 so that air heated or cooled by the heat exchange may be blown into a room during heating or cooling, respectively.

As occasion demands, the vertical wind direction changing blades vertically change the direction of air discharged from the indoor unit 4 and the horizontal wind direction changing blades horizontally change the direction of air discharged from the indoor unit 4.

The compressor 6, the fan, the vertical wind direction changing blades, the horizontal wind direction changing blades, the four-way valve 8, the expansion valve 12, the solenoid valves 30, 42, and the like are electrically connected to a controller 48 (for example, a microcomputer, see Fig. 4).

Operations or actions of the compressor 6, the fan, the vertical wind direction changing blades, the horizontal wind direction changing blades, the four-way valve 8, and the expansion valve 12 are controlled based on control signals from the controller 48, and the two solenoid valves 30, 42 are opened and closed based on control signals from the controller 48.

A relation of connection and functioning of the component parts of the above-described refrigeration cycle equipment are explained hereinafter with a flow of the refrigerant, taking the case of the heating operation.

A refrigerant discharged from a discharge port in the compressor 6 passes through the four-way valve 8 and reaches the indoor heat exchanger 16 via the first refrigerant pipe 18. The refrigerant condenses in the indoor heat exchanger 16 upon heat exchange with indoor air, leaves the indoor heat exchanger 16, and passes through the second refrigerant pipe 20 and through the strainer 10, which prevents invasion of foreign substances into the expansion valve 12, before the refrigerant reaches the expansion valve 12.

The refrigerant is reduced in pressure by the expansion valve 12 and reaches the outdoor heat exchanger 14 via the third refrigerant pipe 22. The refrigerant then evaporates in the outdoor heat exchanger 14 upon heat exchange with outdoor air and passes through the fourth refrigerant pipe 24, the four-way valve 8, the eighth refrigerant pipe 41, and the accumulator 26, before the refrigerant returns to a suction port in the compressor 6.

The fifth refrigerant pipe 28 branched from the first refrigerant pipe 18 between the discharge port in the compressor 6 and the four-way valve 8 joins the third refrigerant pipe 22 between the expansion valve 12 and the outdoor heat exchanger 14 via the first solenoid valve 30.

Furthermore, the heat storage tank 32 accommodating therein the heat storage material 36 and the heat storage heat exchanger 34 is disposed so as to encircle and contact the compressor 6 to store heat generated by the compressor 6 in the heat storage material 36.

The sixth refrigerant pipe 38 branched from the second refrigerant pipe 20 between the indoor heat exchanger 16 and the strainer 10 reaches an inlet of the heat storage heat exchanger 34 via the second solenoid valve 42, and the seventh refrigerant pipe 40 extending from an outlet of the heat storage heat exchanger 34 joins the eighth refrigerant pipe 41 between the four-way valve 8 and the accumulator 26.

At the time of heating Operation of the air conditioner during normal heating is explained hereinafter with reference to Fig. 2 schematically depicting the operation of the air conditioner of Fig. 1 and a flow of the refrigerant during normal heating.
During normal heating, the first solenoid valve 30 and the second solenoid valve 42 are both closed. In this case, as described above, the refrigerant discharged from the discharge port in the compressor 6 passes through the four-way valve 8 and reaches the indoor heat exchanger 16 via the first refrigerant pipe 18.

Having condensed in the indoor heat exchanger 16 upon heat exchange with indoor air, the refrigerant leaves the indoor heat exchanger 16, passes through the refrigerant pipe 20, and reaches the expansion valve 12.

The refrigerant is then reduced in pressure by the expansion valve 12 and reaches the outdoor heat exchanger 14 via the third refrigerant pipe 22. Having evaporated in the outdoor heat exchanger 14 upon heat exchange with outdoor air, the refrigerant passes through the fourth refrigerant pipe 24 and through the four-way valve 8 and returns to the suction port in the compressor 6 through the eighth refrigerant pipe 41.

Heat generated by the compressor 6 is transferred from an outer wall of the compressor 6 to an outer wall of the heat storage tank 32 and stored in the heat storage material 36 accommodated in the heat storage tank 32.
Operation of the air conditioner during defrosting/heating is next explained with reference to Fig. 3 schematically depicting the operation of the air conditioner of Fig. 1 and a flow of the refrigerant during defrosting/heating.

In Fig. 3, solid arrows indicate a flow of refrigerant used for heating, and dotted arrows indicate a flow of refrigerant used for defrosting If frost is formed and grows on the outdoor heat exchanger 14 during the above-discussed normal heating, the airflow resistance of the outdoor heat exchanger 14 increases to thereby reduce the amount of air passing therethrough, thus resulting in a reduction of the evaporating temperature in the outdoor heat exchanger 14.

As shown in Fig. 3, the air conditioner or refrigeration cycle equipment according to the present invention is provided with a piping temperature sensor 44 for detecting a piping temperature of the outdoor heat exchanger 14, and if this piping temperature sensor 44 detects a reduced evaporating temperature compared with an evaporating temperature when no frost is formed, the controller 48 outputs a command to shift the air conditioner from the normal heating operation to the defrosting/heating operation.

When the air conditioner is shifted from the normal heating operation to the defrosting/heating operation, the controller 48 controls the first solenoid valve 30 and the second solenoid valve 42 to open them.

In this case, in addition to the flow of refrigerant during the norma) heating operation as discussed above, part of a gaseous refrigerant discharged from the discharge port in the compressor 6 passes through the fifth refrigerant pipe 28 and the first solenoid valve 30 and joins a refrigerant passing through the third refrigerant pipe 22 to heat the outdoor heat exchanger 14.

Having condensed and turned into a liquid phase, the refrigerant passes through the fourth refrigerant pipe 24 and returns to the suction port in the compressor 6 via the four-way valve 8, the eighth refrigerant pipe 41 and the accumulator 26.

Also, part of a liquid refrigerant diverged from the second refrigerant pipe 20 between the indoor heat exchanger 16 and the strainer 10 passes through the sixth refrigerant pipe 38 and the second solenoid valve 42 and absorbs heat from the heat storage material 36 when passing through the heat storage heat exchanger 34. The liquid refrigerant then evaporates and turns into a gas phase.

The resultant gaseous refrigerant passes through the seventh refrigerant pipe 40, then joins a refrigerant passing through the eighth refrigerant pipe 41, and finally returns to the suction port in the compressor 6 via the accumulator 26.

Although the refrigerant returning to the accumulator 26 contains a liquid refrigerant returning from the outdoor heat exchanger 14, the latter is admixed with a gaseous high-temperature refrigerant returning from the heat storage heat exchanger 34 to thereby promote evaporation of the liquid refrigerant.

Accordingly, it is not likely that a liquid refrigerant may pass through the accumulator 26 and return to the compressor 6, thus making it possible to enhance the reliability of the compressor 6.

At the initiation of defrosting/heating, the temperature of the outdoor heat exchanger 14 is below the freezing point by adhesion of frost, but when the outdoor heat exchanger 14 is heated by the gaseous refrigerant discharged from the discharge port in the compressor 6, frost adhering to the outdoor heat exchanger 14 melts in the vicinity of zero degree and the temperature of the outdoor heat exchanger 14 begins to increase upon termination of melting of the frost.

When the piping temperature sensor 44 detects such a temperature rise of the outdoor heat exchanger 14, a determination is made that defrosting has been completed and the controller 48 outputs a command to shift the defrosting/heating operation to the normal heating operation.

Switching Control between First Heating Operation and Second Heating Operation

In the case of the normal heating operation as shown in Fig. 2, in which no defrosting operation is conducted, the compressor 6 is operated with the two solenoid valves 30, 42 closed and heat generated by the compressor 6 is stored in the heat storage material 36, followed by a gradual increase in temperature thereof.

However, an excessive temperature increase of the heat storage material 36 causes alteration (for example, oxidation) or water evaporation of the heat storage material 36, which in turn sometimes causes deterioration of the heat storage material 36.

Accordingly, in the practice of the present invention, the controller 48 performs a switching control between the first heating operation and the second heating operation, both explained later, to avoid deterioration of the heat storage material 36.

More specifically, the first heating operation is the normal heating operation as shown in Fig. 2, in which the first solenoid valve 30 and the second solenoid valve 42 are both closed and, hence, a refrigerant discharged from the compressor 6 passes through the indoor heat exchanger 16, the expansion valve 12 and the outdoor heat exchanger 14 before it returns to the compressor 6.

In this event, because the second solenoid valve 42 is closed, the refrigerant does not flow through the heat storage heat exchanger 34 and the temperature of the heat storage material 36 accommodated within the heat storage tank 32 is gradually increased by heat generated by the compressor 6.

On the other hand, the second heating operation is the heating operation as shown in Fig. 4, in which the first solenoid valve 30 is closed and the second solenoid valve 42 is opened and, hence, the refrigerant discharged from the compressor 6 passes through the indoor heat exchanger 16 and the heat storage heat exchanger 34 before it returns to the compressor 6.

In this event, a refrigerant flowing through the heat storage heat exchanger 34 heat exchanges in the indoor heat exchanger 16 for heating, followed by a reduction in temperature of the refrigerant. Accordingly, the refrigerant absorbs heat stored in the heat storage material 36, followed by a gradual reduction in temperature of the heat storage material 36 accommodated within the heat storage tank 32.

In this invention, a heat storage material temperature sensor 46 for detecting the temperature of the heat storage material 36 is provided and the controller 48 controls the second solenoid valve 42 based on the temperature detected by the heat storage material temperature sensor 46 to properly select one of the first heating operation and the second heating operation.

Specifically, if the temperature detected by the heat storage material temperature sensor 46 is below a predetermined temperature (for example, 90°C), the first heating operation is conducted to store heat in the heat storage material 36, and if the temperature detected by the heat storage material temperature sensor 46 exceeds the predetermined temperature, the first heating operation is switched to the second heating operation to thereby reduce the temperature of the heat storage material 36.

It is to be noted here that although in this invention the predetermined temperature is set to 90°C, this temperature is selected so as to be below a boiling point of water in the heat storage material 36 in consideration of the boiling point of water.
When the heat storage material 36 stores heat generated by the compressor 6 during the normal operation, the temperature of the heat storage material 36 is about 60-65 °C at the highest. If the temperature of the compressor 6 becomes high due to, for example, an abnormal operation, it is likely that the temperature of the heat storage material 36 may increase locally and come to a boil and, hence, it is necessary to protect the heat storage material 36.

It is conceivable that the air conditioner employing the heat storage device according to the present invention may be installed in a private house at an altitude of up to about 2,000 meters. If so, the boiling point of water falls by 7°C under the influenced of the altitude. Accordingly, the aforementioned predetermined temperature is preferably set to be below 93°C in consideration of an atmospheric pressure in the installation environment.

Also, in the construction according to this embodiment in which the heat storage tank 32 is provided so as to encircle the compressor 6 to store waste heat thereof, the temperature of the heat storage material varies depending on a variation in the degree of contact between the compressor 6 and the heat storage tank 32.

The predetermined temperature may be determined on the assumption that a temperature variation is about ±3°C (for example, a predetermined temperature below 90 °C ). Further, the predetermined temperature may allow for ±4°C in consideration of a tolerance of the sensor (for example, a predetermined temperature below 86°C).

Even if a glycol aqueous solution, a sodium chloride solution or the like other than the ethylene glycol aqueous solution employed in the present invention is used for the heat storage material 36, those predetermined temperatures can be similarly considered from the viewpoint of avoiding evaporation of water contained in the heat storage material 36. Such predetermined temperatures apply to the case of cooling described later.
As described above, according to the present invention, the compressor 6, the indoor heat exchanger 16, the expansion valve 12 and the outdoor heat exchanger 14 are used in the first heating operation, during which heat generated by the compressor 6 is stored in the heat storage material 36 in the heat storage device.

If the temperature of the heat storage material 36 exceeds the predetermined temperature, the controller 48 switches from the first heating operation to the second heating operation, in which the heat storage heat exchanger 34 is used to transfer heat stored in the heat storage material 36 to a refrigerant passing through the heat storage heat exchanger 34, followed by a reduction in temperature of the heat storage material 36.

This control by the controller 48 prevents the temperature of the heat storage material 36 from becoming excessively high and further prevents water evaporation, thus making it possible to avoid deterioration of the heat storage material 36.

In order to reduce the temperature of the heat storage material 36, the frequency of operation of the compressor 6 may be reduced. If the frequency of operation of the compressor 6 is reduced in the second heating operation, the temperature of the heat storage material 36 can be reduced more rapidly.

The rate at which the temperature of the heat storage material 36 reduces differs between a case
where the frequency of operation of the compressor 6 is reduced and a case where the second solenoid valve 42 is opened by switching to the second heating operation.

That is, the temperature reduction is slow where the frequency of operation is reduced, while the temperature reduction is quick where the first heating operation is switched to the second heating operation because the second heating operation is an operation to take heat from the heat storage material 36.

For the purpose of easily controlling the temperature of the heat storage material 36 to be an appropriate one and from the viewpoint of avoiding heat loss that may occur when heat stored is rapidly taken away due to a rapid temperature reduction of the heat storage material 36, an order of priority may be determined such that the frequency of operation of the compressor 6 is first reduced and the first heating operation is subsequently switched to the second heating operation.

At the time of cooling

Operation of the air conditioner during normal cooling is explained hereinafter with reference to Fig. 7 schematically depicting the operation of the air conditioner of Fig. 1 and a flow of the refrigerant during the normal cooling (first cooling).

During normal cooling, the first solenoid valve 30 and the second solenoid valve 42 are both closed. In this case, as described above, the refrigerant discharged from the discharge port in the compressor 6 passes through the fourth refrigerant pipe 24 and reaches the outdoor heat exchanger 14 via the four-way valve 8. Having condensed in the outdoor heat exchanger 14 upon heat exchange with outdoor air, the refrigerant leaves the outdoor heat exchanger 14, passes through the third refrigerant pipe 22, and reaches the expansion valve 12.

The refrigerant is then reduced in pressure by the expansion valve 12 and reaches the indoor heat exchanger 16 via the second refrigerant pipe 20. Having evaporated in the indoor heat exchanger 16 upon heat exchange with indoor air, the refrigerant passes through the first refrigerant pipe 18 and through the four-way valve 8 and returns to the suction port in the compressor 6.

Heat generated by the compressor 6 is transferred from the outer wall of the compressor 6 to the outer wall of the heat storage tank 32 and stored in the heat storage material 36 accommodated in the heat storage tank 32.

Operation of the air conditioner during second cooling is next explained with reference to Fig. 8 schematically depicting the operation of the air conditioner of Fig. 1 and a flow of the refrigerant during the second cooling.

When the air conditioner is shifted from the normal cooling operation (first cooling operation) to the second cooling operation, the controller 48 controls the second solenoid valve 42 to open it. In this case, in addition to the flow of refrigerant during the normal cooling operation as discussed above, part of a liquid refrigerant having passed through the expansion valve 12 and the strainer 10 is diverged from the second refrigerant pipe 20 between the indoor heat exchanger 16 and the strainer 10. The liquid refrigerant then passes through the sixth refrigerant pipe 38 and the second solenoid valve 42 and absorbs heat from the heat storage material 36 when passing through the heat storage heat exchanger 34.

The liquid refrigerant then evaporates and turns into a gas phase. The resultant gaseous refrigerant passes through the seventh refrigerant pipe 40, then joins a refrigerant passing through the eighth refrigerant pipe 41, and finally returns to the suction port in the compressor 6 via the accumulator 26.

Switching Control between First Cooling Operation and Second Cooling Operation

In the case of the normal cooling operation as shown in Fig. 7, in which the compressor 6 is operated with the two solenoid valves 30, 42 closed and heat generated by the compressor 6 is stored in the heat storage material 36, followed by a gradual increase in temperature thereof.
However, an excessive temperature increase of the heat storage material 36 causes alteration (for example, oxidation) or water evaporation of the heat storage material 36, which in turn sometimes causes deterioration of the heat storage material 36.

Accordingly, in the practice of the present invention, the controller 48 performs a switching control between the first cooling operation and the second cooling operation (explained later) to avoid deterioration of the heat storage material 36.

More specifically, the first cooling operation is the normal cooling operation as shown in Fig. 7, in which the first solenoid valve 30 and the second solenoid valve 42 are both closed and, hence, a refrigerant discharged from the compressor 6 passes through the outdoor heat exchanger 14, the expansion valve 12 and the indoor heat exchanger 16 before it returns to the compressor 6.

In this event, because the second solenoid valve 42 is closed, the refrigerant does not flow through the heat storage heat exchanger 34 and the temperature of the heat storage material 36 accommodated within the heat storage tank 32 is gradually increased by heat generated by the compressor 6.

On the other hand, in the second cooling operation, as described above, the first solenoid valve 30 is closed and the second solenoid valve 42 is opened and, hence, the refrigerant discharged from the compressor 6 passes through the outdoor heat exchanger 14 and the heat storage heat exchanger 34 before it returns to the compressor 6.

In this event, a refrigerant flowing through the heat storage heat exchanger 34 heat exchanges in the outdoor heat exchanger 14, followed by a reduction in temperature of the refrigerant. Accordingly, the refrigerant absorbs heat stored in the heat storage material 36, followed by a gradual reduction in temperature of the heat storage material 36 accommodated within the heat storage tank 32.

In the second cooling operation, only the outdoor heat exchanger 14 is on a heat-radiating side, while both the indoor heat exchanger 16 and the heat storage heat exchanger 34 are on a heat-absorbing side. Accordingly, the second cooling operation brings about a disadvantage of reducing the cooling performance, but is sufficiently effective in preventing an excessive temperature increase of the heat storage material 36, which may occur infrequently.

In this invention, a heat storage material temperature sensor 46 for detecting the temperature of the heat storage material 36 is provided and the controller 48 controls the second solenoid valve 42 based on the temperature detected by the heat storage material temperature sensor 46 to properly select one of the first cooling operation and the second cooling operation.

Specifically, if the temperature detected by the heat storage material temperature sensor 46 is below a predetermined temperature (for example, 90°C), the first cooling operation is conducted to allow a temperature increase of the heat storage material 36, and if the temperature detected by the heat storage material temperature sensor 46 exceeds the predetermined temperature, the first cooling operation is switched to the second cooling operation to thereby reduce the temperature of the heat storage material 36.

Although in this invention the predetermined temperature is set to 90°C, this temperature is a temperature selected in consideration of a boiling point of water in the heat storage material 36.
As described above, according to the present invention, the compressor 6, the indoor heat exchanger 16, the expansion valve 12 and the outdoor heat exchanger 14 are used in the first cooling operation, during which heat generated by the compressor 6 is stored in the heat storage material 36 in the heat storage device.

If the temperature of the heat storage material 36 exceeds the predetermined temperature, the controller 48 switches from the first cooling operation to the second cooling operation, in which the heat storage heat exchanger 34 transfers heat stored in the heat storage material 36 to a refrigerant passing through the heat storage heat exchanger 34, followed by a reduction in temperature of the heat storage material 36. This control by the controller 48 prevents the temperature of the heat storage material 36 from becoming excessively high and further prevents water evaporation, thus making it possible to avoid deterioration of the heat storage material 36.
In order to reduce the temperature of the heat storage material 36, the frequency of operation of the compressor 6 may be reduced.

The reduction in frequency of operation of the compressor during cooling results in no reduction or no large reduction in efficiency. Accordingly, if the frequency of operation of the compressor 6 is reduced in the second cooling operation, the temperature of the heat storage material 36 can be reduced more rapidly.

The rate at which the temperature of the heat storage material 36 reduces differs between a case where the frequency of operation of the compressor 6 is reduced and a case where the second solenoid valve 42 is opened by switching to the second cooling operation. That is, the temperature reduction is slow where the frequency of operation is reduced, while the temperature reduction is quick where the first cooling operation is switched to the second cooling operation because the second cooling operation is an operation to take heat from the heat storage material 36.

For the purpose of easily controlling the temperature of the heat storage material 36 to be an appropriate one and in terms of the fact that the reduction in frequency of operation during cooling causes no reduction in efficiency, an order of priority may be determined such that the frequency of operation of the compressor 6 is first reduced and the first cooling operation is subsequently switched to the second cooling operation.

Modification of Switching Control

The following discussion is directed to a control and because heating and cooling are qualitatively the same in objective of the control and also in concept, the discussion is collectively made.

Fig. 5 depicts a modification of the switching control referred to above, in which if the temperature detected by the heat storage material temperature sensor 46 is below the predetermined temperature, the above-described first heating (cooling) operation is conducted, and if the temperature detected by the heat storage material temperature sensor 46 exceeds the predetermined temperature, the second heating (cooling) operation associated with the opening and closing of the second solenoid valve 42 is conducted.

More specifically, during the first heating (cooling) operation with the second solenoid valve 42 closed, if the temperature detected by the heat storage material temperature sensor 46 exceeds the predetermined temperature, the first heating (cooling) operation is switched to the second heating (cooling) operation, in which the controller 48 reduces the frequency of operation of the compressor 6 and gives a control signal to the second solenoid valve 42 to open it for a first predetermined time period (about 1 second).
After a lapse of the first predetermined time period, the controller 48 gives a control signal to the second solenoid valve 42 to close it for a second predetermined time period (about 20 seconds).
When the sum of the first predetermined time period and the second predetermined time period is one cycle length, the opening and closing of the second solenoid valve 42 is performed, for example, ten times during the second heating (cooling) operation. In this modification, the second heating (cooling) operation continues during ten cycles. However, the number of the opening and closing of the second solenoid valve 42 in the second heating (cooling) operation is appropriately selected.

Although the first and second predetermined time periods depend mainly on the size of the second solenoid valve 42, it is generally preferred that the second predetermined time period be longer than the first predetermined time period.

By way of example, the first predetermined time period is set to 1 second and the second predetermined time period is set to 20 seconds. In this case, if the second heating (cooling) operation and the first heating (cooling) operation are repeated ten times, after the switching control between the second heating (cooling) operation and the first heating (cooling) operation has been conducted for 210 seconds, the switching control is switched to the first heating (cooling) operation. In this event, the controller 48 counts the number of ONs in the control signals and if the number of ONs reaches ten, the switching to the first heating (cooling) operation is conducted.

Alternatively, the controller 48 may include a timer 481 for measuring a time period and if the timer 481 measures 210 seconds after the first heating (cooling) operation has been switched to the second heating (cooling) operation, the switching to the first heating (cooling) operation is conducted.

If the temperature detected by the heat storage material temperature sensor 46 becomes the predetermined temperature or less before ten cycles are repeated, the switching to continuous operation of the first heating (cooling) operation may be conducted.

As shown in Fig. 6, the detection temperature of the heat storage material temperature sensor 46 to open and close the second solenoid valve 42 may differ at the time of rise and fall of the temperature of the heat storage material 36 to thereby prevent frequent repetition of the opening and closing of the second solenoid valve 42.

In the example shown in Fig. 6, the second predetermined temperature (for example, about 85 °C) is set to be lower than the first predetermined temperature (for example, about 90°C). If the temperature of the heat storage material 36 is below the first predetermined temperature, the second solenoid valve 42 is maintained closed, and If the temperature of the heat storage material 36 exceeds the first predetermined temperature, the second solenoid valve 42 is opened. If the temperature of the heat storage material 36 becomes the second predetermined temperature or less, the second solenoid valve 42 is closed.

Further, in place of the heat storage material temperature sensor 46 to open and close the second solenoid valve 42 depending on the temperature of the heat storage material 36, a compressor temperature sensor for detecting a temperature of the compressor 6, a discharge refrigerant temperature sensor for detecting a temperature of a refrigerant discharged from the compressor 6, a heat storage tank temperature sensor for detecting a temperature of the heat storage tank 32 itself, a driving current sensor for detecting a driving current of the compressor 6, or the like may be used.

The reason for this is as follows.

• Compressor temperature sensor: the temperature of the compressor 6 has a close connection with the temperature of the heat storage material 36, and if the temperature of the compressor 6 increases, the temperature of the heat storage material 36 also increases.

• Discharge refrigerant temperature sensor: the temperature of the refrigerant discharged from the compressor 6 has a close connection with the temperature of the heat storage material 36, and if the temperature of the discharged refrigerant increases, the temperature of the heat storage material 36 also increases.

• Heat storage tank temperature sensor: the temperature of the heat storage tank 32 basically has a close connection with the temperature of the heat storage material 36, and if the temperature of the heat storage tank 32 increases, the temperature of the heat storage material 36 also increases.

• Driving current sensor: if the driving current of the compressor 6 increases, the temperature of the heat storage material 36 also increases. If the compressor temperature sensor, the discharge refrigerant temperature sensor or the heat storage tank temperature sensor is used in place of the heat storage material temperature sensor 46, it is preferred that the frequent repetition of the opening and closing of the second solenoid valve 42 be prevented by making the detection temperature differ at the time of rise and fall of the temperature, as shown in Fig. 6.

If the driving current sensor for detecting the driving current of the compressor 6 is used in place of the heat storage material temperature sensor 46 and if a current detected by the driving current sensor is below a predetermined current, the first heating (cooling) operation is conducted to
increase the temperature of the heat storage material 36. On the other hand, if the detection current of the driving current sensor exceeds the predetermined current, the first heating (cooling) operation is switched to the second heating (cooling) operation to cool the heat storage material 36.

Alternatively, during the first heating (cooling) operation with the second solenoid valve 42 closed, if the detection current of the driving current sensor exceeds the predetermined current, the frequency of operation of the compressor 6 is reduced and, at the same time, the second solenoid valve 42 is opened to switch the first heating (cooling) operation to the second heating (cooling) operation, which is then continued for the first predetermined time period.

After a lapse of the first predetermined time period, the second solenoid valve 42 is closed to switch the second heating (cooling) operation to the first heating (cooling) operation (in this regard, the frequency of operation of the compressor 6 is maintained in a reduced state), which is then continued for the second predetermined time period, and this process is repeated a predetermined number of times (for example, ten cycles).

As in the case of various temperature sensors referred to above, it is preferred that the frequent repetition of the opening and closing of the second solenoid valve 42 be prevented by making the detection driving current differ at the time of rise and fall of the driving current.

In the above-described embodiments (including the modifications), the switching control between the first heating (cooling) operation and the second heating (cooling) operation is conducted based on the detection result of any one of various sensors. In particular, the use of the timer 481 has been described, in which the switching control from the second heating (cooling)
operation to the first heating (cooling) operation is conducted based on the measuring result of the timer 481.

The switching based on the measuring result of the timer 481 may be conducted in the following manner. That is, if the composition and quantity of the heat storage material 36 are both determined, a time period from when the heat storage material 36 exceeds a predetermined temperature till when the former falls below the latter can be estimated to some extent.

Also, in order to prevent the boiling of the heat storage material 36, it is necessary to precisely switch from the first heating (cooling) operation to the second heating (cooling) operation, but the accuracy of switching from the second heating (cooling) operation to the first heating (cooling) operation is less necessary.

In the present invention, because the composition and quantity of the heat storage material 36 do not change, a time period in which the heat storage material 36 reaches the predetermined temperature after the operation of the compressor 6 and a time period in which the heat storage material 36 falls positively below the predetermined temperature after the former has reached the latter are obtained in advance, for example, through experiments.

When the heat storage material 36 has exceeded the predetermined temperature, the controller 48 sets the time period as obtained to the timer 481 to conduct the switching control from the second heating (cooling) operation to the first heating (cooling) operation after a lapse of the time period set to the timer 481.

Also, in the case where a temperature difference is provided at the time of rise and fall of the temperature of the heat storage material 36, if the composition and quantity of the heat storage material 36 are both determined, the time period from when the heat storage material 36 has reached the first predetermined temperature (for example, 90°C) as shown in Fig. 6 till when the heat storage material 36 returns to the second predetermined temperature (for example, 85°C) is almost determined.

The predetermined temperatures or the predetermined time periods referred to in the above-described controls may be changed at the time of heating and at the time of cooling. Industrial Applicability Because the refrigeration cycle equipment according to the present invention can prevent deterioration of the heat storage material that stores therein heat generated by the compressor, it is effectively applicable to air conditioners, refrigerators, water heaters, heat pump washing machines, and the like.

Explanation of reference numerals 2 outdoor unit, 4 indoor unit, 6 compressor, 8 four-way valve,

10 strainer, 12 expansion valve, 14 outdoor heat exchanger,

16 indoor heat exchanger, 18 first refrigerant pipe,

20 second refrigerant pipe, 22 third refrigerant pipe,

24 fourth refrigerant pipe, 26 accumulator, 28 fifth refrigerant pipe,

30 first solenoid valve, 32 heat storage tank,

34 heat storage heat exchanger, 36 heat storage material,

38 sixth refrigerant pipe, 40 seventh refrigerant pipe,

41 eighth refrigerant pipe, 42 second solenoid valve,

44 piping temperature sensor, 46 heat storage material temperature

sensor, 48 controller, 481 timer.

CLAIMS

1. Refrigeration cycle equipment having a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger, all connected to one another via refrigerant piping, the refrigeration cycle equipment comprising:

a heat storage device comprising:

a heat storage tank;

a heat storage material accommodated in the heat storage tank to store heat generated by the compressor, the heat storage material containing an aqueous solution; and

a heat storage heat exchanger for heat exchanging with the heat storage material; and

a controller operable to switch from a first air conditioning operation, in which a refrigerant discharged from the compressor passes, when a temperature of the heat storage material exceeds
a predetermined temperature below a boiling point of water contained in the heat storage material, through the indoor heat exchanger, the expansion valve and the outdoor heat exchanger, to a second air conditioning operation in which the refrigerant discharged from the compressor passes through the heat storage heat exchanger, the predetermined temperature being unambiguously determined in consideration of the boiling point of water irrespective of the heat storage material.

2. The refrigeration cycle equipment according to claim 1, wherein the predetermined temperature is a first predetermined temperature and if the temperature of the heat storage material falls below a second predetermined temperature, which is lower than the first predetermined temperature, in the second air conditioning operation, the controller switches from the second air conditioning operation to the first air conditioning operation.

3. Refrigeration cycle equipment having a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger, all connected to one another via refrigerant piping, the refrigeration cycle equipment comprising:

a heat storage device comprising:

a heat storage tank;

a heat storage material accommodated in the heat storage tank to store heat generated by the compressor, the heat storage material containing an aqueous solution; and

a heat storage heat exchanger for heat exchanging with the heat storage material; and

a controller operable to switch from a first heating operation, in which a refrigerant discharged from the compressor passes, when a temperature of the heat storage material exceeds a predetermined temperature below a boiling point of water contained in the heat storage material, through the indoor heat exchanger, the expansion valve and the outdoor heat exchanger, to a second heating operation in which the refrigerant discharged from the compressor passes through the indoor heat exchanger and the heat storage heat exchanger, the predetermined temperature being unambiguously determined in consideration of the boiling point of water irrespective of the heat storage material.

4. The refrigeration cycle equipment according to claim 3, wherein the predetermined temperature is a first predetermined temperature and if the temperature of the heat storage material falls below a second predetermined temperature, which is lower than the first predetermined temperature, in the second heating operation, the controller switches from the second heating operation to the first heating operation.

5. The refrigeration cycle equipment according to claim 3 or 4, further comprising a solenoid valve provided on a refrigerant pipe that is branched from another refrigerant pipe for connecting the indoor heat exchanger to the expansion valve and leads to the heat storage heat exchanger, the solenoid valve being opened and closed based on control signals from the controller, wherein the controller switches from the first heating operation to the second heating operation by opening the solenoid valve.
6. The refrigeration cycle equipment according to claim 5, wherein the controller controls the solenoid valve to open the solenoid valve for a first predetermined time period in the second heating operation and then close the solenoid valve for a second predetermined time period.

7. The refrigeration cycle equipment according to claim 6, wherein the second predetermined time period is longer than the first predetermined time period.

8. The refrigeration cycle equipment according to claim 6 or 7, wherein when a sum of the first predetermined time period with the solenoid valve opened and the second predetermined time period with the solenoid valve closed is one cycle length, a switching control of the solenoid valve is repeated a predetermined number of cycles.

9. The refrigeration cycle equipment according to any one of claims 3 to 8, further comprising a heat storage material temperature sensor operable to detect a temperature of the heat storage material, wherein the controller switches from the first heating operation to the second heating operation based on the temperature detected by the heat storage material temperature sensor.

10. The refrigeration cycle equipment according to any one of claims 3 to 8, further comprising a compressor temperature sensor operable to detect a temperature of the compressor, wherein the controller switches from the first heating operation to the second heating operation based on the temperature detected by the compressor temperature sensor.

11. The refrigeration cycle equipment according to any one of claims 3 to 10, wherein a frequency of operation of the compressor is lower in the second heating operation than in the first heating operation.

12. The refrigeration cycle equipment according to any one of claims 3 and 5 to 11, further comprising a timer operable to measure a time period elapsed after the first heating operation has been switched to the second heating operation, wherein if the time period measured by the timer reaches a predetermined time period in the second heating operation, the controller switches from the second heating operation to the first heating operation.

13. Refrigeration cycle equipment having a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger, all connected to one another via refrigerant piping, the refrigeration cycle equipment comprising:

a heat storage device comprising:

a heat storage tank;

a heat storage material accommodated in the heat storage tank to store heat generated by the compressor, the heat storage material containing an aqueous solution; and

a heat storage heat exchanger for heat exchanging with the heat storage material; and
a controller operable to switch from a first cooling operation, in which a refrigerant discharged from the compressor passes, when a temperature of the heat storage material exceeds a predetermined temperature that is below a boiling point of water contained in the heat storage material, through the outdoor heat exchanger, the expansion valve and the indoor heat exchanger, to a second cooling operation in which the refrigerant discharged from the compressor passes, when the temperature of the heat storage material exceeds the predetermined temperature, through the heat storage heat exchanger, the predetermined temperature being unambiguously determined in consideration of the boiling point of water irrespective of the heat storage material.

14. The refrigeration cycle equipment according to claim 13, wherein the predetermined temperature is a first predetermined temperature and if the temperature of the heat storage material falls below a second predetermined temperature, which is lower than the first predetermined temperature, in the second cooling operation, the controller switches from the second cooling operation to the first cooling operation.

15. The refrigeration cycle equipment according to claim 13 or 14, further comprising a solenoid valve provided on a refrigerant pipe that is branched from another refrigerant pipe for connecting the indoor heat exchanger to the expansion valve and leads to the heat storage heat exchanger, the solenoid valve being opened and closed based on control signals from the controller, wherein the controller switches from the first cooling operation to the second cooling operation by opening the solenoid valve.

16. The refrigeration cycle equipment according to claim 15, wherein the controller controls the solenoid valve to open the solenoid valve for a first predetermined time period in the second cooling operation and then close the solenoid valve for a second predetermined time period.

17. The refrigeration cycle equipment according to claim 16, wherein the second predetermined time period is longer than the first predetermined time period.

18. The refrigeration cycle equipment according to claim 16 or 17, wherein when a sum of the first predetermined time period with the solenoid valve opened and the second predetermined time period with the solenoid valve closed is one cycle length, a switching control of the solenoid valve is repeated a predetermined number of cycles.

19. The refrigeration cycle equipment according to any one of claims 13 to 18, further comprising a heat storage material temperature sensor operable to detect a temperature of the heat storage material, wherein the controller switches from the first cooling operation to the second cooling operation based on the temperature detected by the heat storage material temperature sensor.

20. The refrigeration cycle equipment according to any one of claims 13 to 18, further comprising a compressor temperature sensor operable to detect a temperature of the compressor, wherein the controller switches from the first cooling operation to the second cooling operation based on the temperature detected by the compressor temperature sensor.
21. The refrigeration cycle equipment according to any one of claims 13 to 20, wherein a frequency of operation of the compressor is lower in the second cooling operation than in the first cooling operation.

22. The refrigeration cycle equipment according to any one of claims 13 and 15 to 21, further comprising a timer operable to measure a time period elapsed after the first cooling operation has been switched to the second cooling operation, wherein if the time period measured by the timer reaches a predetermined time period in the second cooling operation, the controller switches from the second cooling operation to the first cooling operation.