JP2006329567A - Heat pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump device of high efficiency capable of improving reliability of a compressor. <P>SOLUTION: This heat pump device comprises a refrigerant circuit formed by circularly connecting the compressor 11, an oil separator 12, a refrigerant-side pipe 13a of a hot water supply heat exchanger, an expansion valve 14 and an evaporator 15, and an oil returning circuit for returning oil separated by the oil separator 12 to the compressor 11 through an opening and closing valve 18. As an oil flow in the oil returning circuit is controlled to be increased when an operation frequency of the compressor 11 is high, and the oil flow of the oil returning circuit is controlled to be decreased when the operation frequency of the compressor 11 is low, the constant amount of oil is kept in the compressor 1, thus reliability can be improved, the impairing of performance caused by the bypassing of a discharged refrigerant of the compressor 11 to a suction-side can be prevented, and the operation of high efficiency can be performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-efficiency heat pump device that includes an oil separator and can improve not only the reliability of a compressor but also the performance of a gas cooler and an evaporator.

Conventionally, there is a heat pump apparatus provided with an oil separator as shown in FIG. 3 (see, for example, Patent Document 1). As shown in FIG. 3, in this heat pump apparatus, a compressor 101, an oil separator 102, a condenser 103, a receiver 104, an expansion valve 105, and an evaporator 106 are connected in an annular shape. An oil return circuit 107 is formed between the compressor 101 and the oil separator 102, and a supercooling control valve 108 is connected to the oil return circuit 107 in the middle of the piping. The refrigerant gas discharged from the compressor 101 (including oil for lubricating the compressor 101) is separated into refrigerant gas and oil by the oil separator 102, and only the refrigerant gas is the condenser 103, the receiver 104, the expansion valve 105, and the evaporator 106. And return to the compressor 101. On the other hand, the oil separated by the oil separator 102 is returned to the compressor 101 by the oil return circuit 107. At this time, when the temperature and pressure of the fluid flowing from the bottom of the oil separator 102 to the oil return circuit 107 are detected, the combination of the temperature and pressure of the fluid is a value corresponding to the refrigerant supercooling region, that is, When this fluid is oil, the supercooling control valve 108 is opened, and this fluid (oil) is returned to the compressor 101 via the oil return circuit 107. Thereby, since only the refrigerant flows through the heat exchangers of the condenser 103 and the evaporator 106, it is possible to prevent the performance from being deteriorated due to oil, and to improve the operation efficiency of the heat pump device. Further, since only the oil is returned to the compressor 101 by the supercooling valve 108, the reliability of the compressor 101 can be improved.
JP-A-6-241588

  However, in the conventional configuration, when the operating state of the heat pump device changes rapidly, it is difficult to accurately detect the supercooling state from the temperature and pressure of the fluid flowing through the oil return circuit 107. The timing of opening the valve 108 is delayed and the oil supply to the compressor 101 is delayed, thereby causing problems such as seizure, or the supercooling control valve 108 is opened more than necessary and the refrigerant gas other than oil returns to the compressor 101 to cause a heat pump. The operation efficiency of the device may be reduced.

  The present invention solves the above-described conventional problems, and by appropriately controlling the oil return amount of the compressor in response to changes in the compressor operating state, it is possible to achieve high efficiency while ensuring the reliability of the compressor. An object is to provide a heat pump device.

  In order to solve the above-described conventional problems, a heat pump device according to the present invention includes a refrigerant circuit formed by annularly connecting a compressor, an oil separator, a gas cooler, an expansion valve, and an evaporator, and oil separated by the oil separator. And an oil return circuit that returns the oil to the compressor via an oil flow control device, wherein the oil flow control device uses the oil flow when the operation frequency of the compressor is a reference frequency as a reference oil flow, and the compressor When the operating frequency of the compressor is higher than the reference frequency, the oil flow rate of the oil return circuit is increased by a predetermined amount. When the operating frequency of the compressor is lower than the reference frequency, the oil flow rate of the oil return circuit is determined. Decrease only by quantification.

  Thereby, the oil return amount of the compressor can be appropriately controlled in accordance with the change in the compressor operating state, and both the reliability of the compressor and the highly efficient operation can be achieved.

  When the compressor operating frequency is high, increase the oil flow rate in the oil return circuit, and when the compressor operating frequency is low, decrease the oil flow rate in the oil return circuit, so that the compressor oil return amount Appropriately controlled in response to changes in conditions, it is possible to ensure both the reliability of the compressor and high-efficiency operation.

  According to a first aspect of the present invention, there is provided a refrigerant circuit formed by annularly connecting a compressor, an oil separator, a gas cooler, an expansion valve, and an evaporator, and oil separated by the oil separator via the oil flow control device. When the operating frequency of the compressor is a reference frequency, the oil flow rate control device uses the oil flow rate when the operating frequency of the compressor is a reference frequency as a reference oil flow rate, and the operating frequency of the compressor is higher than the reference frequency. Increases the oil flow rate of the oil return circuit by a predetermined amount, and reduces the oil flow rate of the compressor by decreasing the oil flow rate of the oil return circuit by a predetermined amount when the operating frequency of the compressor is lower than the reference frequency. The return amount is appropriately controlled in response to the change in the compressor operating state, so that both the reliability of the compressor and the highly efficient operation can be achieved.

  In the second invention, in particular, the oil flow control device of the heat pump device of the first invention is such that the oil return circuit is closed when the operating frequency of the compressor is less than a predetermined value. It is possible to prevent a reduction in operating efficiency due to the refrigerant returning to the compressor via the oil return circuit.

  According to a third aspect of the invention, in particular, the oil flow rate control device of the heat pump device according to the first or second aspect of the invention has a first timer for detecting the cumulative operation time of the compressor, and the detection time of the first timer When the amount of time exceeds the specified cumulative time, a predetermined amount of oil is allowed to flow through the oil return circuit, and the oil discharged from the compressor excessively accumulates in the oil separator, resulting in insufficient oil in the compressor. The reliability of the compressor can be improved.

  According to a fourth aspect of the invention, in particular, the oil flow rate control device of the heat pump device according to any one of the first to third aspects of the invention has a second timer for detecting the cumulative operation time of the compressor for each predetermined frequency range. When a detection time of the two timers exceeds a predetermined integration time, a predetermined amount of oil is allowed to flow through the oil return circuit. When the operating frequency of the compressor is high, the predetermined integration time is shortened, and the operating frequency of the compressor When the engine speed is low, by setting the predetermined integration time longer, the amount of oil retained by the compressor can be controlled more accurately, and the reliability of the compressor can be improved.

  In particular, the fifth aspect of the invention relates to the first temperature sensor for detecting the pipe temperature upstream of the oil flow control device of the heat pump apparatus of any one of the first to fourth inventions and the pipe temperature downstream of the oil flow control device. A second temperature sensor for detecting, wherein the oil flow control device opens an oil return circuit when the operating frequency of the compressor is equal to or higher than a predetermined value, the oil return circuit is open, and the first temperature sensor And when the temperature difference detected by the second temperature sensor is equal to or greater than a predetermined temperature, it is determined that the refrigerant is flowing in the oil return circuit and the oil return circuit is closed. It is possible to prevent a decrease in operating efficiency due to the flow of the refrigerant.

  In the sixth invention, in particular, the refrigerant circuit of the heat pump device according to any one of the first to fifth inventions is a supercritical heat pump cycle in which the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure, and the pressure is increased to the critical pressure or higher. Since the refrigerant in the gas cooler is heated to a critical pressure or higher by heating the fluid in the gas cooler with the refrigerant, the refrigerant in the gas cooler may condense even if the temperature is lowered due to the heat taken away by the fluid in the gas cooler. Absent. Therefore, it becomes easy to form a temperature difference between the refrigerant and the fluid throughout the gas cooler, and the heat exchange efficiency can be increased.

  In the heat pump device according to the sixth aspect of the invention, in particular, the heat pump device according to the sixth aspect uses carbon dioxide as a refrigerant to be used, and reduces the product cost by using relatively inexpensive and stable carbon dioxide as the refrigerant. , Reliability can be improved. In addition, carbon dioxide has an ozone depletion coefficient of zero and a global warming coefficient of about 1/700 of the alternative refrigerant HFC-407C, which is very small.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a heat pump device according to a first embodiment of the present invention.

  In FIG. 1, a compressor 11, an oil separator 12, a refrigerant side pipe 13 a of a hot water supply heat exchanger, an expansion valve 14, and an evaporator 15 are annularly connected to form a refrigerant circuit. By using the gas cooler of the heat pump device as a hot water supply heat exchanger, it has the function of a heat pump water heater. The evaporator 15 has a fan 16, and heat exchange is performed between the air supplied to the evaporator 15 by the fan 16 and the refrigerant in the evaporator 15, and the refrigerant is heated. In addition, an oil return circuit is provided in which oil separated by the oil separator 12 is returned to the compressor 11 via the on-off valve 18. The on-off valve 18 is opened when it is detected by the first timer 23 that the accumulated operation time of the compressor 11 has exceeded a predetermined accumulated time. The on-off valve 18 uses the oil flow rate when the operation frequency of the compressor 11 is the reference frequency (the operation frequency of the compressor 11 for obtaining the standard heating capacity of the heat pump device) as the reference oil flow rate, and operates the compressor 11. When the frequency is higher than the reference frequency, the oil flow rate of the oil return circuit is increased by a predetermined amount. When the operating frequency of the compressor 11 is lower than the reference frequency, the oil flow rate of the oil return circuit is decreased by a predetermined amount. The open / close state is controlled by the first timer 23 and the open / close valve control device 24. A capillary tube 17 is connected in the middle of the piping connecting the oil separator 12 and the on-off valve 18. Since this capillary tube 17 has a constant pressure reducing action, the oil flow rate in the oil return circuit when the on-off valve 18 is opened is prevented from rapidly increasing, and the compressor 11 is damaged by oil compression. Therefore, the reliability can be improved. Moreover, the hot water storage tank 19, the laminated pump 20, and the water side pipe 13b of the hot water supply heat exchanger are connected in an annular shape to form a boiling circuit. The water at the bottom of the hot water storage tank 19 is conveyed by the stacking pump 20 to the water side pipe 13b of the hot water heat exchanger, where it exchanges heat with the refrigerant in the refrigerant side pipe 13a of the hot water heat exchanger. And returned to the upper part of the hot water storage tank 19. A hot water supply pipe 21 for supplying water to the hot water storage tank 19 is connected to the bottom of the hot water storage tank 19, and a hot water supply pipe 22 for taking out hot water from the hot water storage tank 19 is connected to the upper part of the hot water storage tank 19.

  About the heat pump apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  A predetermined amount of oil is sealed inside the compressor 11 for the purpose of lubricating the sliding portion. As a characteristic of the compressor 11, the amount of oil discharged from the compressor 11 generally increases as the operating frequency increases.

  Therefore, first, when the operating frequency of the compressor 11 is higher than the reference frequency (70 Hz) (for example, within the range of 71 to 120 Hz and the oil discharge amount from the compressor 11 is large), the opening and closing The valve control device 24 increases the amount of oil flowing through the oil return circuit by increasing the time during which the on-off valve 18 is open, and maintains the amount of oil in the compressor 11.

  Next, when the operating frequency of the compressor 11 is lower than the reference frequency (for example, within the range of 50 to 69 Hz and the amount of oil discharged from the compressor 11 is relatively small), the on-off valve control device 24. Thus, the flow rate of the oil flowing through the oil return circuit is reduced by shortening the time during which the on-off valve 18 is open, and the oil amount of the compressor 11 is maintained.

  When the operating frequency of the compressor 11 is lower (for example, less than 50 Hz and the amount of oil discharged from the compressor 11 is smaller), the on-off valve control device 24 always closes the on-off valve 18. In addition to maintaining the amount of oil in the compressor 11, it is possible to prevent the refrigerant from returning to the compressor 11 via the oil return circuit, and to suppress a reduction in operating efficiency of the heat pump device.

  As described above, in the first embodiment, the oil amount of the compressor can be kept constant by controlling the oil flow rate flowing through the oil return circuit in accordance with the operating frequency of the compressor. Reliability can be improved. In addition, it is possible to prevent the performance of the heat exchanger from being deteriorated due to the oil flowing into the hot water supply heat exchanger or the evaporator, and it is possible to operate the heat pump device with high efficiency.

(Embodiment 2)
FIG. 2 is a configuration diagram of the heat pump apparatus according to the second embodiment of the present invention. In FIG. 2, the same components as those of the heat pump apparatus according to the first embodiment of the present invention are denoted by common reference numerals, and detailed description thereof is omitted.

  The difference from the first embodiment is that instead of the first timer 23, a first temperature sensor 25 for detecting the piping temperature upstream of the capillary tube 17 and a second temperature sensor for detecting the piping temperature downstream of the capillary tube 17 are provided. The oil flow control device 24 opens the on-off valve 18 when the operating frequency of the compressor 11 is equal to or higher than a predetermined value, the on-off valve 18 is open, and the first temperature sensor 25 and the second temperature sensor 26. The on-off valve 18 is closed when the temperature difference detected in the above is greater than or equal to a predetermined value.

  About the heat pump apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  When the operating frequency of the compressor 11 is equal to or higher than a reference frequency (for example, 70 Hz), the on-off valve control device 24 opens the on-off valve 18 to flow oil to the oil return circuit to hold the oil amount of the compressor 11.

  Since the pressure is reduced when the fluid passes through the capillary tube 17, when the fluid is only incompressible oil, there is no temperature difference between the fluid before and after the capillary tube 17, that is, the first temperature sensor. The difference between the detection values of 25 and the second temperature sensor 26 hardly occurs. On the other hand, when the fluid flowing in the capillary tube 17 is oil containing a relatively large amount of refrigerant, the temperature of the oil is lowered when the refrigerant is decompressed. Therefore, when the temperature difference detected by the first temperature sensor 25 and the second temperature sensor 26 is equal to or greater than a predetermined value, it is determined that a relatively large amount of refrigerant is flowing in the capillary tube 17 and the on-off valve 18 is opened. Close. As a result, when the amount of refrigerant flowing through the oil return circuit increases, the oil return circuit is quickly closed, thereby preventing performance deterioration caused by bypassing the refrigerant discharged from the compressor 11 to the suction side of the compressor 11. It is possible to operate the heat pump device with high efficiency.

  In the first and second embodiments, the oil flow rate in the oil return circuit is controlled by opening and closing the on-off valve 18, but instead of the on-off valve 18, a flow rate like a needle valve is continuously increased. A flow control valve that can be changed may be used. By continuously changing the oil flow rate, the rapid fluctuation of the oil flow rate returned to the compressor 11 is reduced, and the oil amount in the compressor 11 can be kept constant with higher accuracy.

  In Embodiments 1 and 2, the cycle of the refrigerant circuit is a supercritical heat pump cycle in which the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure. It may be a cycle. In this case, chlorofluorocarbon, ammonia, or the like may be used as the refrigerant.

  As described above, the heat pump device according to the present invention can keep the amount of oil in the compressor constant, and is effective in improving the reliability of the heat pump cycle, particularly the compressor.

Configuration diagram of heat pump device in Embodiment 1 of the present invention The block diagram of the heat pump apparatus in Embodiment 2 of this invention Configuration diagram of a conventional heat pump device

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Compressor 12 Oil separator 13 Hot-water supply heat exchanger 13a Refrigerant-side piping of hot-water supply heat exchanger 13b Water-side piping of hot-water supply heat exchanger 14 Expansion valve 15 Evaporator 16 Fan 17 Capillary tube 18 On-off valve 19 Hot water storage tank 20 Multilayer pump 21 Water supply pipe 22 Hot water supply pipe 23 First timer 24 On-off valve controller 25 First temperature sensor 26 Second temperature sensor

Claims (7)

A refrigerant circuit formed by annularly connecting a compressor, an oil separator, a gas cooler, an expansion valve, and an evaporator; and an oil return circuit that returns oil separated by the oil separator to the compressor via an oil flow control device; The oil flow rate control device uses an oil flow rate when the operation frequency of the compressor is a reference frequency as a reference oil flow rate, and when the operation frequency of the compressor is higher than the reference frequency, the oil return circuit A heat pump device characterized in that the oil flow rate is increased by a predetermined amount, and when the operating frequency of the compressor is lower than the reference frequency, the oil flow rate of the oil return circuit is decreased by a predetermined amount. The heat pump apparatus according to claim 1, wherein the oil flow control device closes the oil return circuit when the operating frequency of the compressor is less than a predetermined value. The oil flow control device has a first timer for detecting the cumulative operation time of the compressor, and when a detection time of the first timer becomes equal to or longer than a predetermined integration time, the oil flow circuit flows a predetermined amount of oil through the oil return circuit. The heat pump device according to claim 1, wherein the heat pump device is a heat pump device. The oil flow control device has a second timer for detecting the cumulative operation time of the compressor for each predetermined frequency range, and is provided in the oil return circuit when the detection time of the second timer becomes equal to or longer than the predetermined integration time. The oil is allowed to flow in a fixed amount, and when the operating frequency of the compressor is high, the predetermined integrated time is shortened, and when the operating frequency of the compressor is low, the predetermined integrated time is set long. The heat pump device according to any one of 1 to 3. A first temperature sensor for detecting a pipe temperature upstream of the oil flow control device and a second temperature sensor for detecting a pipe temperature downstream of the oil flow control device, wherein the oil flow control device has an operating frequency of the compressor; The oil return circuit is opened when the oil pressure is greater than or equal to a predetermined value, and the oil return circuit is opened when the oil return circuit is open and the temperature difference detected by the first temperature sensor and the second temperature sensor is greater than or equal to the predetermined value. The heat pump device according to any one of claims 1 to 4, wherein the heat pump device is closed. The heat pump device according to any one of claims 1 to 5, wherein the refrigerant circuit is a supercritical heat pump cycle in which a refrigerant pressure on a high pressure side is equal to or higher than a critical pressure. The heat pump device according to claim 6, wherein the refrigerant used is carbon dioxide.