HEAT STORAGE DEVICE AND AIR CONDITIONER HAVING SAME

Technical Field

The present invention relates to a heat storage device disposed around a compressor and accommodating a heat storage material that stores therein heat generated by the compressor and also to an air conditioner having the heat storage device.

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).

Figs. 9 and 10 are cross-sectional views of an example of a conventional heat storage device. In Figs. 9 and 10, a heat storage device 100 includes a hermetic heat storage box 106 generally in the form of a hollow cylinder disposed around a compressor 103, which acts as a heat generator, a heat storage material 104 filled in the hermetic heat storage box 106, a heat exchanger 108 for heat storage and radiation accommodated within the hermetic heat storage box 106, and the like.

As shown in Fig. 10 depicting a sectional view taken along a line X-X in Fig. 9, the hermetic heat storage box 106 is formed into a generally hollow cylinder by sealing an upper opening of a casing 110 made of, for example, an aluminum thin plate and the heat storage material 104 is accommodated within the casing 110. The heat exchanger 108 is formed of, for example, a pipe 112 for passage of a refrigerant, to which aluminum fins 114 have been secured.

In the heat storage device 100 of the above-describe construction, when the compressor 102 is in operation, heat generated by the compressor 102 is transferred to the hermetic heat storage box 106 via silicon oil 116 and stored in the heat storage material 104 within the hermetic heat storage box 106. Patent Document(s)

Patent Document 1: JP 2-128065 U

Summary of the Invention

Problems to be solved by the Invention

In the heat storage device 100 disclosed in Patent Document 1, as shown in Fig. 10, the refrigerant pipe 112 is disposed within the heat storage device 100 over a wide range from a location adjacent to an upper end to another location adjacent to a lower end. However, a temperature distribution of the heat storage material 104 is not uniform, i.e., the heat storage material 104 contains a high-temperature portion and a low-temperature portion, thus posing a problem that the heat storage device 100 of the above-described construction cannot perform efficient heat exchange.

The present invention has been developed to overcome the above-described disadvantage.

It is accordingly an objective of the present invention to provide a heat storage device capable of efficiently heat exchanging with a heat storage material that stores heat generated by a compressor and also to provide an air conditioner employing such a heat storage device.

Means to Solve the Problems

In accomplishing the above objective, the present invention is directed to a heat storage device disposed around a compressor to store heat generated by the compressor. The heat storage device includes a heat storage tank accommodating a heat storage material to store heat generated by the compressor and a heat storage heat exchanger accommodated within the heat storage tank, wherein a center of gravity or a center of an entire pipe of the heat storage heat exchanger is positioned above a vertical center of the heat storage tank.

Effects of the Invention

In the heat storage device of the above-described construction, heat from the compressor is stored in the heat storage material, but the temperature of the heat storage material is higher at an upper portion of the heat storage tank than at a lower portion of the heat storage tank. In the practice of the present invention, the center of gravity of the heat storage heat exchanger is determined so as to be positioned above the vertical center of the heat storage tank and, hence, the heat storage heat exchanger can efficiently heat exchange with the high-temperature 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.

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 perspective view of the heat storage device according to the present invention with a compressor and an accumulator installed.

Fig. 5 is an exploded perspective view of the heat storage device of Fig. 4.

Fig. 6 is a perspective view of tine lieat storage device of Fig. 4.

Fig. 7 Is a cross-sectional view taken along a line VII-VII In Fig. 6.

Fig. 8 Is a cross-sectional view taken along a line VIII-VIII In Fig. 6.

Fig. 9 Is a horizontal sectional view of a conventional heat storage device.

Fig. 10 Is a cross-sectional view taken along a line X-X in Fig. 9.

Embodiments for Carrying out the Invention

The present invention Is directed to a heat storage device disposed around a compressor to store heat generated by the compressor. The heat storage device includes a heat storage tank accommodating a heat storage material to store heat generated by the compressor and a heat storage heat exchanger accommodated within the heat storage tank. A center of gravity or a center of an entire pipe of the heat storage heat exchanger Is positioned above a vertical center of the heat storage tank.

By this construction, even if a temperature distribution of the heat storage material accommodated within the heat storage tank is not uniform, the heat storage heat exchanger can efficiently heat exchange with a high-temperature heat storage material.

Also, the heat storage tank Includes a bent portion and a straight portion extending straight from the bent portion, and the bent portion has a lower end that is positioned preferably below and adjacent to the vertical center of the heat storage tank, thereby making it possible to contact all the heat storage heat exchanger with the heat storage material having as high a temperature as possible.

Specifically, the bent portion of the heat storage tank has an upper end, a position of which is determined such that even if the heat storage tank Is inclined, the bent portion of the heat storage heat exchanger is always submerged in the heat storage material. This configuration allows the bent portion of the heat storage heat exchanger to be always held in contact with the heat storage material, thus resulting in efficient heat exchange.

In another aspect of the present invention, an air conditioner includes a compressor and a heat storage device of the above-described type disposed around the compressor.

Embodiments of the present invention are explained hereinafter with reference to the drawings.

Fig. 1 depicts a piping diagram of an air conditioner having a heat storage device 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 compressor 6 are connected to each other via a fourth refrigerant pipe 24.

The four-way valve 8 is located midway on the fourth refrigerant pipe 24, and an accumulator 26 for separating a liquid phase refrigerant and a gas phase refrigerant is provided on the fourth refrigerant pipe 24 on a 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.

Also, the second refrigerant pipe 20 and the heat storage heat exchanger 34 are connected to each other via a sixth refrigerant pipe , 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 and controlled by a controller (for example, a microcomputer not shown).

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, 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 fourth refrigerant pipe 24 between the four-way valve 8 and the accumulator 26.

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.

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 according to the present invention is provided with a temperature sensor 44 for detecting a piping temperature of the outdoor heat exchanger 14, and if this temperature sensor 44 detects a reduced evaporating temperature compared with an evaporating temperature when no frost is formed, the controller 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 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 normal 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 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 fourth refrigerant pipe 24, 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/lieating, 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 temperature sensor 44 detects such a temperature rise of the outdoor heat exchanger 14, a detemnination is made that defrosting has been completed and the controller outputs a command to shift the defrosting/heating operation to the normal heating operation.

Figs. 4 and 5 depict the heat storage device. As described above, the heat storage device includes the heat storage tank 32, the heat storage heat exchanger 34 and the heat storage materia! 36. Fig. 4 depicts a state in which the compressor 6 and the accumulator 26 attached to the compressor 6 have been installed in the heat storage device. Fig. 5 is an exploded perspective view of the heat storage device.

As shown in Fig. 5, the heat storage tank 32 includes an upwardly open tank body 46 made of a resin and having a side wall 46a and a bottom wall (not shown), a lid 48 made of a resin for closing an upper opening of the tank body 46, and a packing 50 made of, for example, a silicon rubber and interposed between the tank body 46 and the lid 48. The lid 48 is screwed to the tank body 46. The side wall 46a of the tank body 46 is partly open (part of the side wall 46a confronting the compressor 6) and a contact member 52 is joined to a peripheral edge of this opening 46b to be brought into close contact with an outer surface of the compressor 6.

The contact member 52 includes a frame 54 and a sheeted member 56 and is in the form of a cylinder of a predetermined diameter, a portion of which has been cut away, as a whole. The compressor 6 is accommodated inside the contact member 52 and, hence, the inner diameter of the contact member 52 Is slightly greater than the outer diameter of the compressor 6 in consideration of a mounting tolerance and the like.

The frame 54 has an opening 54a defined therein from an Intermediate portion to a lower portion thereof in the vertical direction. The sheeted member 56 Is joined to the frame 54 to close the opening 54a.

The heat storage heat exchanger 34 is made of, for example, a copper pipe bent into a serpentine configuration and is accommodated within the tank body 46. Also, the heat storage heat exchanger 34 has opposite ends extending upward from the lid 48. One end of the heat storage heat exchanger 34 is connected to the sixth refrigerant pipe 38 (see Fig. 1) and the other end of the heat storage heat exchanger 34 is connected to the seventh refrigerant pipe 40 (see Fig. 1). The heat storage heat exchanger 34 Is accommodated in an internal space of the tank body 46, which is delimited by the side wall 46a, the bottom wall and the contact member 52 and In which the heat storage material 36 Is filled.

The heat storage device Is not provided with any agitating means for agitating the heat storage material 36 filled therein, a temperature distribution of which is accordingly not uniform. In this invention. In view of efficient heat exchange, the heat storage heat exchanger 34 bent into a serpentine configuration Is disposed at an upper portion of the heat storage tank 32.

That is, the amount of heat exchange between a refrigerant passing through the heat storage heat exchanger 34 and the heat storage material 36 for heat exchanging with the refrigerant increases with an increase In temperature difference, followed by a reduction in time period for defrosting, but a high-temperature refrigerant 36 gathers at an upper portion inside the heat storage tank 32 and a low-temperature refrigerant 36 gathers at a lower portion inside the heat storage tank 32. As shown in Figs. 6 to 8, the heat storage heat exchanger 34 has a bent portion 34a and two straight portions 34b extending upwardly straight from opposite ends of the bent portion 34a, and the bent portion 34a Is entirely disposed inside the tanl< body 46 so as to snake along an inner wall surface of the tank body 46 within a predetermined range of the upper portion of the heat storage tank 32.

A detailed explanation is made with reference to Fig. 7. The height of the heat storage tank 32 from a bottom surface thereof Is Indicated by H1, the height of a center of the heat storage tank 32 from the bottom surface thereof is indicated by H2 (H2=H1/2), the height of a lower end of the bent portion 34a of the heat storage heat exchanger 34 from the bottom surface of the heat storage tank 32 is Indicated by H3, and the distance from an upper surface of the heat storage tank 32 to an upper end of the bent portion 34a of the heat storage heat exchanger 34 is indicated by H4. In this invention, H3 and H4 are set to a predetermined height and a predetermined distance, respectively.

The vertical position CoB of the center of gravity of the heat storage heat exchanger 34 is set to be higher than the vertical position H2 of the center of the heat storage tank 32. It is to be noted that the vertical position CoB of the center of gravity of the heat storage heat exchanger 34 is a position of the center of gravity of a combination of the bent portion 34a and the straight portions 34b of the heat storage heat exchanger 34. In the heat storage device, heat generated by the compressor 6 Is stored in the heat storage material 36, but the temperature of the heat storage material 36 located at an upper portion of the heat storage tank 32 is higher than that of the heat storage material 36 located at a lower portion of the heat storage tank 32. In the practice of the present Invention, because the vertical position of the center of gravity of the heat storage heat exchanger 34 is set to be higher than the vertical position of the center of the heat storage tank 32, the heat storage heat exchanger 34 performs heat exchange mainly with a high-temperature portion of the heat storage material 36. In other words, the heat storage heat exchanger 34 according to the present invention can efficiently heat exchange with the heat storage material 36.

Also, in this embodiment, the height H3 of the lower end of the heat storage heat exchanger 34 is lower than the height H2 of the center of the heat storage tank 32 and positioned in the vicinity of the center of the heat storage tank 32. As a result, the entire heat storage heat exchanger 34 is mostly held in contact with the high-temperature heat storage material 36, thereby allowing the heat storage heat exchanger 34 to efficiently heat exchange with the heat storage material 36.

On the other hand, the distance H4 from the upper surface of the heat storage tank 32 to the upper end of the bent portion 34a of the heat storage heat exchanger 34 is determined in consideration of an inclination of the heat storage tank 32. That is, the compressor 6 and the heat storage tank 32 are generally accommodated within the outdoor unit 2, which is sometimes installed outside at an angle. In consideration of such an inclination, the heat storage heat exchanger 34 is installed within the heat storage tank 32 such that the upper end of the bent portion 34a of the heat storage heat exchanger 34 is positioned below the upper surface of the heat storage tank 32 by the predetermined distance H4. The reason for this is that when the heat storage material 36 is filled in the heat storage tank 32 to the extent that the lid 48 does not soak in the heat storage material 36, even if the heat storage tank 32 is inclined at a predetermined angle (for example, about 7 degrees with respect to an installation surface), the bent portion 34a of the heat storage heat exchanger 34 is always submerged in the heat storage material 36.

Although in this embodiment the heat storage device is detachably mounted on the compressor 6, an outer shell of the compressor 6 and the tank body 46 of the heat storage tank 32 may be each made of a metal and both of them may be firmly fixed to each other by, for example, welding. Even in the heat storage tank of the fixed type, the mounting position of the heat storage heat exchanger 34 can be determined as described above.

Further, although in this embodiment the heat storage heat exchanger 34 has been described as being accommodated within the heat storage tank 32, the heat storage heat exchanger may be directly wound around the outer surface of the compressor 6. In this case, also, the mounting position of the heat storage heat exchanger 34 can be determined as in the above-described embodiment.

Although in this embodiment the position of the center of gravity of the heat storage heat exchanger 34 has been described as being higher than H2, the present invention is not limited to this and a center of an entire pipe of the heat storage heat exchanger 34 may be positioned above H2.

Industrial Applicability

In the heat storage device according to the present invention, because the installation position of the heat storage heat exchanger within the heat storage tank is properly determined in consideration of efficient heat exchange, the heat storage device according to the present invention 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, 34a bent portion, 34b straight portion,
36 heat storage material, 38 sixth refrigerant pipe.
40 seventh refrigerant pipe, 42 second solenoid valve,
44 temperature sensor, 46 heat storage tank body,
46a side wall, 46b opening in side wall, 48 lid, 50 packing,
52 contact member, 54 frame, 54a opening, 56 sheeted member.

CLAIMS

1. A heat storage device disposed around a compressor to store heat generated by the compressor, comprising:
a heat storage tank accommodating a heat storage material to store heat generated by the compressor; and
a heat storage heat exchanger accommodated within the heat storage tank;
wherein a center of gravity or a center of an entire pipe of the heat storage heat exchanger is positioned above a vertical center of the heat storage tank.

2. The heat storage device according to claim 1, wherein the heat storage tank comprises a bent portion and a straight portion extending straight from the bent portion, and the bent portion has a lower end that is positioned below and adjacent to the vertical center of the heat storage tank

3. The heat storage device according to claim 1, wherein the bent portion of the heat storage tank has an upper end, a position of which is determined such that even if the heat storage tank is inclined, the bent portion of the heat storage heat exchanger is submerged in the heat storage material.

4. An air conditioner comprising:
a compressor; and
a heat storage device according to claim 1 disposed around the compressor.