JP3801168B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a water heater provided with a heat pump circuit in which a compressor, a heat exchanger for hot water supply, an expansion valve, and an evaporator are connected by refrigerant piping, and particularly relates to a refrigeration cycle stabilization technique at the time of starting the compressor.

  Conventionally, a water heater using a heat pump cycle using a variable capacity compressor has been proposed (see, for example, Patent Document 1).

A scroll compressor as shown in FIG. 6 is used as the variable capacity compressor. FIG. 6 is a sectional view of a typical scroll compressor. The fixed scroll 101 and the orbiting scroll 102 in which the spiral wrap rises from the end plate are meshed to form a compression chamber 103 therebetween, and the orbiting scroll 102 is driven by the rotation restraint mechanism 104. When the swirl is performed along a circular orbit under the restraint of rotation, the compression chamber 103 moves while changing its volume, thereby sucking, compressing and discharging the refrigerant. Between the orbiting scroll 102 and the fixing member 105 that backs up the back side of the orbiting scroll 102, a high pressure portion 106 that applies high pressure by lubricating oil is provided at the center of the back surface of the orbiting scroll 102. Is provided with a back pressure chamber 108 for applying a predetermined pressure (back pressure) lower than that of the high pressure portion 106 to the outer peripheral portion of the back surface, and the orbiting scroll 102 is fixed by these high pressure and back pressure. By pressing against the scroll component 101, the orbiting scroll 102 is prevented from falling over from the fixed scroll component 101 (see, for example, Patent Document 2).
JP 2003-247759 A Japanese Patent Laid-Open No. 2002-266776

  However, in the refrigeration cycle using the scroll compressor as described above, when the high-pressure refrigerant pressure is low and the low-pressure refrigerant pressure is high, that is, in an operating state where the compression ratio is low, the force that presses the rotating scroll against the fixed sucrose. As a result, the pressure of the high-pressure refrigerant compressed in the compression chamber increases, the turning scroll moves away from the fixed scroll, and the refrigerant in the high-pressure compression chamber leaks into the low-pressure compression chamber. Therefore, there is a problem that the amount of refrigerant circulating through the refrigeration cycle is reduced, and as a result, the refrigeration capacity is also reduced.

  In addition, if the pressing force acting on the back of the orbiting scroll is increased in order to suppress rollover at a low compression ratio, an excessive pressing force may be generated on the orbiting scroll and cause abnormal wear under high compression ratio operating conditions. For this reason, there is a problem that the pressing force acting on the back of the orbiting scroll cannot be increased.

  In particular, when the heat pump is activated, the evaporator pressure increases and the pressure difference of the refrigeration cycle decreases when the blower is activated in accordance with the activation of the scroll compressor. The operation becomes unstable, and it becomes a capsized state, and there is a problem that the reliability of the scroll compressor is lowered or the refrigerant piping is vibrated greatly to generate abnormal noise.

  The present invention secures a pressure difference in the refrigeration cycle in the heat pump device when the heat pump device is started, and minimizes the time during which the operation of the scroll compressor becomes unstable and overturns. It is an object of the present invention to provide a heat pump device that can ensure reliability and prevent noise and vibration of refrigerant piping.

  In order to solve the above-mentioned problems, the present invention is characterized in that the evaporator blower is started after a predetermined time has elapsed since the start of the compressor, and prevents the pressure of the evaporator of the heat pump from becoming high. Since the operation of the scroll compressor becomes unstable and the time for the rollover state is minimized, the reliability of the scroll compressor is ensured and the noise and vibration of the refrigerant piping are prevented. be able to.

  According to the present invention, when the heat pump device is started, a pressure difference is ensured in the refrigeration cycle in the heat pump device, and the scroll compression is achieved by minimizing the time during which the operation of the scroll compressor becomes unstable and overturns. The reliability of the machine can be ensured and the noise and vibration of the refrigerant piping can be prevented.

A first invention includes a scroll compressor, a hot water supply heat exchanger, a decompression device, a heat pump circuit configured by annularly connecting an evaporator with a refrigerant pipe, and a blower that changes the evaporator capacity of the heat pump circuit. The pressure detection means provided on the low pressure side from the outlet of the decompression device to the scroll compressor, and the outside air temperature detection means for detecting the outside air temperature, the detection value in the pressure detection means has reached a predetermined value Sometimes, when the blower is started and the outside air temperature is equal to or higher than a predetermined value, the blower is started after a predetermined time after the detected value of the pressure detecting means reaches a predetermined value. -Since the pressure of the evaporator of the pump is prevented from being increased and the operation can be performed while ensuring a pressure difference in the refrigeration cycle, the operation of the scroll compressor becomes unstable more reliably and the time for the overturning state is minimized. Noise of the refrigerant pipe or to ensure the reliability of the scroll compressor by, it is possible to prevent vibration. In addition, when the outside air temperature is equal to or higher than a predetermined value, the pressure detection means is not activated, and is activated after a predetermined time, so that the pressure of the evaporator in the heat pump device is likely to rise rapidly due to activation of the blower device. When the outside air temperature is high, the blower can be started after sufficiently lowering the low pressure, so that the scroll compressor can be prevented from being overturned again, and the reliability of the scroll compressor can be ensured.

In the second invention, the rotational speed of the blower is increased stepwise, and after the blower is started, the pressure of the evaporator of the heat pump can be raised stepwise without sudden increase. It is possible to more reliably prevent the scroll compressor from being overwhelmed again because the compression ratio cannot be obtained, so that the reliability of the scroll compressor can be ensured and the noise and vibration of the refrigerant piping can be prevented.

In a third aspect of the invention, the heat pump circuit is a supercritical heat pump cycle in which the pressure of the refrigerant is equal to or higher than the critical pressure. By heating the hot water or air, the refrigerant in the hot water heat exchanger is equal to or higher than the critical pressure. Therefore, it does not condense even if the temperature drops due to the heat of the hot water supply heat exchanger. Therefore, it becomes easy to form a temperature difference between the refrigerant and water over the entire area of the heat exchanger for hot water supply, so that hot water can be obtained and the heat exchange efficiency can be increased.

In the fourth invention, carbon dioxide is used as a refrigerant to be used. By using carbon dioxide, which is relatively inexpensive and stable, as a refrigerant, product cost can be suppressed and 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, a heat pump water heater in an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a configuration diagram of a heat pump water heater in Embodiment 1 of the present invention. FIG. 2 is a Mollier diagram of the operation of the heat pump device in the present embodiment, showing the normal time and the overturning of the scroll compressor. The heat pump circuit circulates the refrigerant by connecting the scroll compressor 1, the hot water supply heat exchanger 2, the decompression device 3, and the evaporator 4 through a refrigerant pipe 5. And the air blower 9 which changes the evaporator capability of a heat pump circuit is attached. In this heat pump circuit, it is preferable to use carbon dioxide as a refrigerant and operate on the high pressure side in a state exceeding the critical pressure.

  In the hot water storage circuit, the hot water storage tank 6 and the heat absorber 2 are connected by a water pipe 8 to circulate water from a pump 7. The hot water supply heat exchanger 2 is used as a heat exchanger in a heat pump device and as a heat exchanger in a heat absorber in a hot water storage device. It is a water-refrigerant heat exchanger that exchanges heat between the refrigerant of the radiator 2 of the heat pump device and the water of the heat absorber 2 of the hot water storage device. The absorbed water becomes warm water and is stored in the hot water tank 6 for use.

  The scroll compressor 1 compresses and discharges the sucked refrigerant, and the discharged high-temperature and high-pressure refrigerant exchanges heat with the liquid (water) supplied from the hot water storage tank 6 via the hot water supply heat exchanger 2. The Since the refrigerant (carbon dioxide) flowing through the hot water supply heat exchanger 2 is pressurized by the scroll compressor 1, the refrigerant passes through the liquid passing through the hot water supply heat exchanger 2 and condenses even if the temperature is lowered (two refrigerant phases). Do not). The decompression device 3 is a device that decompresses refrigerant (carbon dioxide) flowing out of the hot water supply heat exchanger 2 and is an electromagnetic expansion valve that electrically controls the valve opening. The refrigerant (carbon dioxide) is decompressed by the decompression device 3 until it reaches the refrigerant two-phase region, and then the endothermic refrigerant is evaporated and evaporated by the evaporator 4 and then sucked into the scroll compressor 1 again.

  However, when the load on the evaporator 4 side is large, that is, when the outside air temperature is high or when the scroll compressor 1 is started, the pressure difference of the refrigeration cycle cannot be taken as shown in FIG. Becomes unstable, and the scroll compressor 1 is overturned. Further, the scroll compressor 1 and the refrigerant pipe 5 vibrate greatly, and abnormal noise is generated. In particular, at the start of operation (at the time of startup), the refrigeration cycle tends to become unstable (overturned state).

  FIG. 3 is a time chart of the refrigeration cycle high and low pressure of the blower and the heat pump circuit. The rotational speed of the blower 9 is uniformly determined by the operating frequency, and in the conventional control, as indicated by the one-dot chain line in FIG. Since the target rotational speed is reached, the pressure of the evaporator 4 becomes large at the time of start-up, and it takes time for the difference in pressure of the refrigeration cycle to be taken to the extent that the scroll compressor 1 starts up and recovers from overturning because the differential pressure cannot be taken. It will take.

In order to solve such a problem, in the control according to the present invention, when the heat pump circuit is activated, that is, after the scroll compressor 1 is activated, the air blower 9 is activated after being stopped for a predetermined time (T). vessel 4 pressure Ki out to the fall times are faster short time operation of the scroll compressor 1 can ensure a high-low pressure difference in the refrigeration cycle (low pressure) is formed of a rollover state becomes unstable shortest scroll compressor 1 can be ensured, and noise and vibration of the refrigerant pipe 5 can be prevented.

(Embodiment 2)
FIG. 4 is a time chart of the air blower and the refrigeration cycle high / low pressure when the heat pump device according to the second embodiment of the present invention is started. In this embodiment, the pressure detection means 10 is provided, and after the scroll compressor 1 is started, the blower 9 is stopped until the pressure detection means 10 becomes a predetermined pressure P or less after the scroll compressor 1 is started, and then the blower 9 is started. Since the blower is started in a state where the low pressure is sufficiently lowered by setting the predetermined pressure P so that the scroll compressor 1 reliably returns from the capsized state, the operation of the scroll compressor can be performed more reliably. It is possible to minimize the time of instability and the overturning state, to ensure the reliability of the scroll compressor, and to prevent noise and vibration of the refrigerant piping.

(Embodiment 3)
The present embodiment includes an outside air temperature detecting means 11 for detecting the outside air temperature. When the outside air temperature is equal to or higher than a predetermined temperature, even if the pressure detecting means 10 becomes equal to or lower than the predetermined pressure P after the scroll compressor 1 is started. The blower 9 is started after the blower 9 is stopped for a predetermined time (T), and the scrolling is performed even when the outside air temperature at which the pressure of the evaporator 4 in the heat pump device is likely to rise rapidly due to the start of the blower 9 is high. Since the blower 9 is started after the pressure is sufficiently lowered so that the compressor 1 does not overturn again, the scroll compressor 1 can be reliably prevented from being overturned again by the start of the blower 9. 1 reliability can be ensured, and noise and vibration of the refrigerant piping can be prevented.

(Embodiment 4)
FIG. 5 is a time chart of the blower when the heat pump circuit is activated in the present embodiment. As shown in FIG. 5, the air volume of the blower 9 is increased stepwise by a predetermined value N rotation (rpm) every predetermined time T1, and the airflow of the blower 9 is increased stepwise instead of all at once. Even when the target rotational speed is large, after the blower 9 is started, the pressure of the evaporator 4 in the heat pump device can be increased stepwise without sudden increase. Therefore, it is possible to more reliably prevent the rollover state from occurring again, and to ensure the reliability of the scroll compressor 1 and to prevent noise and vibration of the refrigerant piping.

  In addition, although each said embodiment demonstrated the case where it had a hot water storage tank, you may be the instantaneous water heater type heat pump hot-water supply apparatus which takes out the hot water heated with the heat exchanger for hot water supply as it is. Note that the liquid in the hot water tank 6 may be used not only for hot water supply but also for floor heating and indoor air conditioning. Furthermore, an accumulator for storing the refrigerant may be installed on the refrigerant suction side of the scroll compressor 1.

  As described above, the present invention is not limited to a refrigerant that condenses on the high pressure side as a refrigerant, but a refrigerant that can be in a supercritical state (for example, R32, carbon dioxide, ethane, ethylene, nitrogen oxide, and a mixed refrigerant containing them). It can also be used in applications such as water heaters used (hot water heaters), hot water heaters (water heaters) that instantaneously boil hot water heated by a heat exchanger for hot water supply, air conditioners, and vehicle air conditioners (car air conditioners). .

The block diagram of the heat pump water heater in Embodiment 1 of this invention Mollier diagram of operation of heat pump circuit in the same heat pump water heater Air blower of the heat pump circuit and refrigeration cycle high / low pressure time chart The air blower of the heat pump circuit of the heat pump water heater in Embodiment 2 of this invention, and the refrigeration cycle high-low pressure time chart The air blower of the heat pump circuit of the heat pump water heater in Embodiment 4 of this invention, and the refrigeration cycle high-low pressure time chart Cross section of scroll compressor

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Scroll compressor 102 Heat exchanger for hot water supply 104 Evaporator 109 Blower 110 Pressure detection means (sensor)
111 Outside temperature detection means (sensor)

Claims (4)

A scroll compressor, a hot water heat exchanger, a decompressor, a heat pump circuit configured by connecting an evaporator in an annular shape by a refrigerant pipe, a blower for changing the evaporator capacity of the heat pump circuit, and an outlet of the decompressor Pressure detecting means provided on the low pressure side from the compressor to the scroll compressor, and an outside air temperature detecting means for detecting the outside air temperature, and when the detected value at the pressure detecting means reaches a predetermined value, The heat pump water heater is activated, and when the outside air temperature is equal to or higher than a predetermined value, the air blower is activated after a predetermined time after the detection value of the pressure detection means reaches a predetermined value . The heat pump water heater according to claim 1 , wherein the rotational speed of the blower is increased stepwise. The heat pump water heater according to claim 1 or 2 , wherein the heat pump 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. The heat pump water heater according to any one of claims 1 to 3, wherein the refrigerant used in the heat pump circuit is carbon dioxide.

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