JPH04222359A - Heat pump type air conditioner - Google Patents

Abstract

PURPOSE:To maintain heating capacity by a method wherein a heater, in which heat exchange between refrigerant and heating medium is effected, and a bypass pipe, connecting the heater to the suction side of a compressor, are provided while the set value of the discharging pressure of a compressor is changed in accordance with the change of heating load. CONSTITUTION:Upon heating operation utilizing outside air as a heat absorbing source, a circuit is changed over as shown by broken lines and the supply of hot-water to a heater 21 is stopped. Upon the heating operation utilizing hot-water as a heat absorbing source, refrigerant from a compressor 1 passes through a four-way transfer valve 2, a room heat exchanger 8 and a choking device 7 and is evaporated by absorbing heat from the hot-water in the heater 21, then, is returned to the compressor 1 through a first opening and closing valve 24 and a bypass pipe 23. When a room temperature is changed in accordance with the fluctuation of heating load, the room temperature is detected by a temperature sensor 28 and is compared with a set temperature from a setting means 47 in a comparing means 46, then, the set value of a high pressure is determined in accordance with a control rule from a storage means 49 to increase or decrease the value travel of a control valve 22 and operate so as to maintain the set pressure after it is changed. According to this method, the heat absorbing source of the refrigerant is selected by an outside air temperature and heating capacity can be maintained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner.

0002

[Prior Art] Fig. 2 is a system diagram showing an example of a conventional heat pump type air conditioner. , an indoor heat exchanger 8, an indoor fan 9, etc.

During cooling operation, the four-way switching valve 2 is switched as shown by the solid line. Then, the high temperature and high pressure refrigerant gas discharged from the compressor 1 passes through the four-way switching valve 2 as shown by the solid arrow.
It then enters the outdoor heat exchanger 3, where it is condensed and liquefied by radiating heat to the outside air sent by the outdoor fan 4. Next, most of this refrigerant liquid flows to the other side of the parallel pipe due to the flow resistance caused by the heating throttle device 5 installed in one of the parallel pipes, passes through the check valve 6, and then enters the throttle device 7. The air enters the indoor heat exchanger 8 after being throttled and reduced in pressure. And the refrigerant is this indoor heat exchanger 8
In the process of flowing through the air, the indoor air is cooled by exchanging heat with the indoor air sent by the indoor fan 9, and is evaporated into refrigerant gas, which passes through the four-way switching valve 2 and then flows into the accumulator 10. The refrigerant liquid is separated from the refrigerant gas and then sucked into the compressor 1 where it is compressed again.

During heating operation, the four-way switching valve 2 is switched as shown by the broken line. Then, the refrigerant gas discharged from the compressor 1 flows into the indoor heat exchanger 8 via the four-way switching valve 2 as shown by the broken line arrow, and is sent by the indoor fan 9 in the process of flowing through the indoor heat exchanger 8. By exchanging heat with the indoor air, it heats the indoor air and condenses itself into a liquid. Next, this refrigerant liquid is reduced in pressure by being throttled in the process of flowing through the expansion device 7 and the heating expansion device 5, and then enters the outdoor heat exchanger 3, where it absorbs heat from the outside air sent by the outdoor fan 4. is vaporized by evaporation. This refrigerant gas then enters the accumulator 10 after passing through the four-way switching valve 2, where the refrigerant liquid is separated from the refrigerant gas, and is then sucked into the compressor 1 where it is compressed again.

[0005]

[Problems to be Solved by the Invention] The conventional heat pump type air conditioner described above has the following problems to be solved.

That is, in the conventional heat pump type air conditioner, the heat absorption source of the refrigerant during heating operation is due to the outside air, so there is a problem that the heating capacity decreases as the outside temperature decreases. As a countermeasure for this, some air conditioners supplement the heating capacity by heating the indoor air with an auxiliary heater when the outside temperature is low, but converting electricity directly into heat is expensive. However, there were unfavorable problems in terms of economy and safety, such as localized heat build-up. In view of the above-mentioned problems, an object of the present invention is to provide a heat pump type air conditioner that maintains heating capacity by using a heat source such as hot water or combustion gas in addition to outside air as a heat absorption source of a refrigerant.

[0007]

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention provides a refrigerant circuit in which a compressor, an outdoor heat exchanger, a throttle device, and an indoor heat exchanger are connected to each other so that outside air is transferred to the outside during heating operation. In a heat pump air conditioner using a refrigerant as a heat absorption source in a heat exchanger, a heater that heats a refrigerant interposed between the outdoor heat exchanger and the expansion device by exchanging heat with a heating medium; A bypass pipe is connected between the heater and the outdoor heat exchanger at one end and the other end is connected to the suction side of the compressor, and the refrigerant is directed to either the bypass pipe or the outdoor heat exchanger. and a control means for increasing or decreasing the set value of the discharge pressure of the compressor to increase or decrease the amount of heating medium supplied to the heater as the heating load increases or decreases. An object of the present invention is to provide a heat pump type air conditioner characterized by:

[0008]

[Function] Since the present invention has the above structure, it has the following function.

During heating operation using outside air as a heat absorption source, the switching means switches the flow of the refrigerant toward the outdoor heat exchanger, and the flow of the heating medium to the heater is stopped. As a result, the refrigerant discharged from the compressor is condensed and liquefied by dissipating heat to the indoor air in the indoor heat exchanger, is depressurized by the throttling device, and then enters the outdoor heat exchanger, where it absorbs heat from the outside air and evaporates. It is vaporized and then returned to the compressor to complete the heating cycle.

On the other hand, during heating operation using the heating medium as a heat absorption source,
By means of the switching means, the flow of the refrigerant is switched in the direction of the bypass pipe and the heating medium is passed through the heater. As a result, the refrigerant discharged from the compressor is condensed and liquefied by dissipating heat to the indoor air in the indoor heat exchanger, then reduced in pressure by the expansion device, and then enters the heater, where it absorbs heat from the heating medium and evaporates. The air then returns to the compressor via a bypass pipe to complete the heating cycle.

[0011] Furthermore, when the heating load increases during this heating operation, the set value of the discharge pressure of the compressor (hereinafter referred to as high pressure) is increased, and the amount of heat absorbed by the refrigerant in the heater increases in order to maintain this set pressure. As a result, the amount of heat released by the refrigerant in the indoor heat exchanger is increased. On the other hand, when the heating load decreases, the set value of the high pressure is lowered, and in order to maintain this set pressure, the amount of heat absorbed by the refrigerant in the heater is reduced, and as a result, the amount of heat released by the refrigerant in the indoor heat exchanger is reduced.

0012

[Embodiment] An embodiment of the present invention will be explained with reference to FIG. Note that the same reference numerals are given to the same constituent members as in the conventional example, and explanations thereof will be omitted unless necessary.

FIG. 1 is a system diagram of a heat pump type air conditioner according to this embodiment. As shown in the figure, a heater 21 is interposed between an outdoor heat exchanger 3 and a throttle device 7. Heater 21
The refrigerant is heated by exchanging heat with the heating medium, and there are various types of heating medium that serve as the heat absorption source of the refrigerant, such as electric heaters and combustion gas, but in this example, hot water is used. Hot water is allowed to flow through the heater 21 via a control valve 22 .

One end of the bypass pipe 23 is connected between the outdoor heat exchanger 3 and the heater 21, and the other end of the bypass pipe 23 is connected to the suction side of the compressor 1, in this embodiment, the inlet pipe of the accumulator 10. . A first on-off valve 24 is interposed in this bypass pipe 23, and a second on-off valve 26 is interposed between the outdoor heat exchanger 3 and a branch point 25 of the bypass pipe 23.
The flow direction of the refrigerant is switched by opening and closing the on-off valve 24 and the second on-off valve 26. That is, a bypass pipe 23 is provided in parallel to the outdoor heat exchanger 3, and the refrigerant can be passed either in the direction of the outdoor heat exchanger 3 or in the direction of the bypass pipe 23 by bypassing the outdoor heat exchanger 3. It's like it's being washed away. Here, the second on-off valve 26 is a reversible valve that allows refrigerant to flow in both directions of the valve 26. Note that the first
Instead of the on-off valve 24 and the second on-off valve 26, a three-way switching valve may be interposed at the branch point 25 of the bypass pipe 23 to switch the flow direction of the refrigerant. A check valve 30 is interposed between the other end 29 of the bypass pipe 23 and the four-way switching valve 2, and the check valve 30 allows the refrigerant to flow only toward the suction side of the compressor 1. Further, 27 is a pressure sensor that detects the pressure (hereinafter referred to as high pressure) in the discharge pipe 11 of the compressor 1 during heating operation, and 28 is a temperature sensor that detects the room temperature.
The controller 40 inputting the signals from the pressure sensor 27 and the temperature sensor 28 raises or lowers the set value of the high pressure, and also increases or decreases the opening degree of the control valve 22 based on commands from the controller 40. ing.

The rest of the structure is similar to the conventional one shown in FIG. 2, and corresponding members are given the same reference numerals as mentioned above. During heating operation using outside air as a heat absorption source, the four-way switching valve 2 is switched as shown by the broken line, and the first on-off valve 24 is closed and the second on-off valve 26 is opened. Further, the flow of hot water to the heater 21 is stopped. Then, the high-temperature, high-pressure refrigerant gas discharged from the compressor 1 passes through the four-way switching valve 2 and enters the indoor heat exchanger 8 as shown by the broken line arrow, where it is condensed and liquefied by heating the indoor air and then throttled. The pressure is reduced in the device 7, and after passing through the heater 21 and the second on-off valve 26, the pressure is reduced in the heating throttle device 5. Next, this refrigerant enters the outdoor heat exchanger 3, where it absorbs heat from the outside air sent by the outdoor fan 4 and is evaporated.
The heating cycle is then returned to the compressor 1 and the heating cycle is completed.

On the other hand, during heating operation using hot water as a heat absorbing source, the four-way switching valve 2 is switched as shown by the broken line in the same way as above.
The first on-off valve 24 is opened and the second on-off valve 26 is closed. Furthermore, the control valve 22 is opened and hot water is allowed to flow through the heater 21 . Then, the high-temperature, high-pressure refrigerant gas discharged from the compressor 1 passes through the four-way switching valve 2 and the discharge pipe 11, as shown by the dashed line, and reaches the indoor heat exchanger 8, where it is condensed by heating the indoor air. After being liquefied, the pressure is reduced by the expansion device 7. Next, this refrigerant absorbs heat from the hot water in the process of flowing through the heater 21 and is evaporated and vaporized, passes through the first on-off valve 24, passes through the bypass pipe 23, passes through the accumulator 10, and then returns to the compressor 1 to complete the heating cycle. do.

[0017] As described above, during heating operation, the refrigerant can absorb heat from the outside air via the outdoor heat exchanger 3 or from the hot water which is the heating medium via the heater 21, so the heat absorption source of the refrigerant can be adjusted as appropriate depending on the outside air temperature. By selecting this option, the heating capacity of the air conditioner can be maintained.

Further, during heating operation using hot water as a heat absorption source, the discharge pressure of the compressor 1, that is, the high pressure is detected by the pressure sensor 27 and input to the comparison means 41 of the controller 40. In the comparison means 41, the high pressure is determined by the setting means 42.
The deviation between the two is calculated by comparing it with the set pressure inputted from. This deviation is input to the opening determining means 43, where the opening of the control valve 22 is determined according to the control rule input from the storage means 44. Here, the storage means 44 stores control rules (for example, PID control, table comparison control, etc.) for determining the opening degree of the control valve 22 in accordance with the deviation and its rate of change. The determined opening degree is outputted to the control valve 22 via the output means 45, and the control valve 22 becomes the determined opening degree. Thus, when the high pressure exceeds the set pressure, the opening of the control valve 22 decreases and the amount of heat absorbed by the refrigerant in the heater 21 is reduced, while when the high pressure falls below the set pressure, the opening of the control valve 22 increases. The amount of heat absorbed by the refrigerant in the heater 21 is increased, and as a result, the high pressure is always maintained at the set pressure.

Further, during this heating operation, when the indoor heat exchanger 8 releases too much or insufficient heat from the refrigerant due to fluctuations in the indoor heating load and the room temperature changes, this room temperature is detected by the temperature sensor 28 and the controller 40 comparison means 4
6 is output. In the comparison means 46, the room temperature is compared with the set temperature inputted from the setting means 47, and the deviation between the two is calculated. This deviation is input to the high pressure determining means 48, where the set value of the high pressure is determined according to the control rule input from the storage means 49. Here, the storage means 49 stores control rules for determining the high pressure corresponding to the deviation, the set temperature, and the heat release amount of the refrigerant in the indoor heat exchanger 8. The set value of the determined high pressure is output to the setting means 42, and the set pressure of the setting means 42 is changed to the above set value. As a result, the air conditioner is operated to maintain the changed set pressure by increasing or decreasing the opening degree of the control valve 22 described above.

When the heating load increases in this way, the set pressure of the setting means 42 is increased based on a command from the high pressure determining means 48, and in order to maintain this set pressure, the amount of heat absorbed by the refrigerant in the heater 21 is increased via the control valve 22. increases, and as a result, the amount of heat released by the refrigerant in the indoor heat exchanger 8 increases, and the room temperature is raised to the set temperature. On the other hand, when the heating load decreases, the set pressure of the setting means 42 is lowered based on a command from the high pressure determining means 48, and the refrigerant in the heater 21 is passed through the control valve 22 to maintain this set pressure. As a result, the amount of heat absorbed by the refrigerant in the indoor heat exchanger 8 is reduced, and the room temperature is lowered to the set temperature. Therefore, since the set value of the high pressure is changed in accordance with the increase or decrease in the heating load, the heating capacity of the air conditioner can be controlled to match the heating load. As described above, according to this embodiment, even if the outside temperature drops and the efficiency of heat absorption from the outside air by the outdoor heat exchanger 3 decreases, the heat absorption from hot water is switched to the heat absorption through the heater 21, and the desired amount of heat is achieved. Since the heating temperature is maintained, there is an advantage that the disadvantage of conventional heat pump air conditioners, which is that the heating capacity decreases in cold weather, is eliminated.

[0021]

Effects of the Invention Since the present invention is constructed as described above, it has the following effects.

That is, according to the present invention, during heating operation, the refrigerant can absorb heat from the outside air through the outdoor heat exchanger or from the heating medium through the heater. The heating capacity of the air conditioner can be maintained by appropriately selecting the heat source. This results in
A heat pump type air conditioner whose heating capacity does not decrease even in cold weather can be obtained.

[0023] Also, as the heating load increases or decreases, the set value of the discharge pressure of the compressor increases or decreases, and the amount of heat absorbed by the refrigerant in the heater increases or decreases, which in turn increases or decreases the amount of heat released by the refrigerant in the indoor heat exchanger. Therefore, the heating capacity of the air conditioner can be controlled to match the heating load.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a heat pump air conditioner according to an embodiment of the present invention.

FIG. 2 is a system diagram of a conventional heat pump air conditioner.

[Explanation of symbols]

1 Compressor 3 Outdoor heat exchanger 4 Outdoor fan 7 Squeezing device 8 Indoor heat exchanger 21 Heater 22 Control valve 23 Bypass pipe 24 First on-off valve 26 Second on-off valve 27 Pressure sensor 28 Temperature sensor 40 Controller 42 Setting means 48 High voltage determining means

Claims (1)

[Claims] 1. A heat pump type air conditioner in which a compressor, an outdoor heat exchanger, a throttle device, and an indoor heat exchanger are connected to form a refrigerant circuit, and the outside air is used as a heat absorption source for the refrigerant in the outdoor heat exchanger during heating operation. In the machine, a heater that heats a refrigerant interposed between the outdoor heat exchanger and the expansion device by exchanging heat with a heating medium, and an end between the heater and the outdoor heat exchanger. a bypass pipe whose other end is connected to the suction side of the compressor, a switching means for switching the flow of refrigerant to either the bypass pipe or the outdoor heat exchanger, and an increase or decrease in heating load. A heat pump type air conditioner characterized by comprising: control means for increasing or decreasing the set value of the discharge pressure of the compressor to increase or decrease the amount of heating medium supplied to the heater.