JP2014088965A - Hot water supplying machine - Google Patents

Abstract

A water heater excellent in reliability capable of preventing freezing of a water heat exchanger is provided.
SOLUTION: During the defrosting operation, a defrosting circuit is formed in which the refrigerant discharged from the compressor returns to the compressor through the four-way valve, outdoor heat exchanger, decompressor, bypass path, and four-way valve with the on-off valve closed. To do. Then, during this defrosting operation, the circulation pump is operated when the temperature detected by the refrigerant temperature sensor provided in the pipe between the on-off valve and the water heat exchanger falls below a set value.
[Selection] Figure 1

Description

  Embodiments of the present invention relate to a hot water heater that warms hot water in a hot water tank by operation of a heat pump refrigeration cycle.

  2. Description of the Related Art There is known a water heater that has a hot water tank and warms hot water in the hot water tank by operating a heat pump refrigeration cycle.

  The heat pump refrigeration cycle forms a heating circuit in which high-temperature refrigerant discharged from the compressor returns to the compressor through a four-way valve, a water heat exchanger, a decompressor, an outdoor heat exchanger, and the four-way valve. . With the formation of this heating circuit, hot water is stored in the hot water supply tank by circulating hot water in the hot water supply tank through the water heat exchanger.

  In such a water heater, when the outside air temperature becomes low, frost gradually adheres to the outdoor heat exchanger, and if it is left as it is, the amount of heat pumped from the outside air decreases and the amount of heating to the hot water decreases.

  As a countermeasure, when the outdoor heat exchanger is frosted, the four-way valve is switched to form a defrost circuit in which the refrigerant discharged from the compressor flows directly to the outdoor heat exchanger, and the outdoor heat exchanger is defrosted with the heat of the high-temperature refrigerant. A defrosting operation is performed. In this defrosting operation, a refrigerant bypass path is provided in parallel with the water heat exchanger so that cryogenic refrigerant flowing out of the outdoor heat exchanger does not flow into the water heat exchanger. Moreover, in order to interrupt | block the inflow of the refrigerant | coolant to a water heat exchanger, an on-off valve is provided in piping connected to a water heat exchanger, and the on-off valve is closed with formation of a defrost circuit.

JP 2003-222391 A

  When the defrosting circuit is formed, the refrigerant leaks from the on-off valve that should be closed for some reason, such as when dust is caught in the on-off valve, and it may flow into the water heat exchanger. When this happens, the water heat exchanger freezes and the hot water in the hot water supply tank cannot be heated.

  An object of an embodiment of the present invention is to provide a reliable hot water heater that can prevent freezing of a water heat exchanger.

  The hot water supply apparatus of claim 1 is connected to a hot water tank, a compressor, a four-way valve, a water heat exchanger, an on-off valve, a decompressor, and an outdoor heat exchanger in this order, and a pipe between the on-off valve and the decompressor. A heat pump refrigeration cycle having a bypass from the four-way valve to the water heat exchanger, a circulation pump for circulating hot water in the hot water supply tank through the water heat exchanger, and the water heat exchanger And a refrigerant temperature sensor for detecting the temperature of the refrigerant passing through the pipe between the opening / closing valve and a control means. The control means is a defrosting circuit in which the refrigerant discharged from the compressor returns to the compressor through the four-way valve, the outdoor heat exchanger, the decompressor, the bypass passage, and the four-way valve with the on-off valve closed. When the temperature detected by the refrigerant temperature sensor falls below a set value during the defrosting operation, the circulation pump is operated.

The figure which shows the structure of each embodiment. The flowchart which shows the control of 1st Embodiment. The figure which shows the correspondence of the detection temperature of the refrigerant temperature sensor in each embodiment, and the some zone defined with respect to the detection temperature. The figure which shows the rotation speed setting conditions of the circulation pump in each embodiment. The figure which shows the correspondence of the detection temperature of the water temperature sensor in each embodiment, and the some zone defined with respect to the detection temperature. The figure which shows the rotation speed correction conditions of the circulation pump in each embodiment. The flowchart which shows the control of 2nd Embodiment.

[1] A water heater according to the first embodiment will be described.
As shown in FIG. 1, the outdoor unit 10, the hydrothermal exchange unit 20, and the hot water tank unit 30 are connected to each other by piping. A control unit 50 is wired to the outdoor unit 10, the hydrothermal exchange unit 20, and the hot water tank unit 30, and an operation / display unit 51 is wired to the control unit 50.

  The next heat pump refrigeration cycle is configured by pipe connection in the outdoor unit 10 and the hydrothermal exchange unit 20.

  Reference numeral 11 denotes a compressor that sucks and compresses a refrigerant. One end of a water heat exchanger 22 is connected to a discharge port of the compressor 11 via a four-way valve 12 and an open / close valve, for example, a two-way valve 21, and the water heat exchange is performed. One end of the outdoor heat exchanger 14 is connected to the other end of the condenser 22 via an on-off valve such as a pulse motor valve (PMV) 23 and a decompressor such as an electric expansion valve 13. The other end of the outdoor heat exchanger 14 is connected to a suction port of the compressor 11 through the four-way valve 12.

  In the heating operation, as indicated by a solid line arrow, a high-temperature refrigerant (gas refrigerant) discharged from the compressor 11 flows to the water heat exchanger 22 through the four-way valve 12 and the two-way valve 21, and the water heat exchanger The refrigerant liquefied by heat exchange with hot water at 22 flows through the pulse motor valve 23 and the electric expansion valve (for example, pulse motor valve) 13 to the outdoor heat exchanger 14. The refrigerant that has flowed into the outdoor heat exchanger 14 is pumped from the outside air to be vaporized, and the vaporized refrigerant is sucked into the compressor 11 through the four-way valve 12. By the formation of this heating circuit, hot water passing through the water heat exchanger 22 is heated.

  The two-way valve 21 is an electromagnetic type that switches between opening and closing depending on whether the energization is on or off. The two-way valve 21 opens when the heating circuit is formed, and closes when the defrosting circuit to be described later is formed to close the water heat exchanger 22. The refrigerant flow is blocked in the gas side piping of the heat pump refrigeration cycle. The pulse motor valve 23 has a degree of opening that changes continuously according to the number of input driving pulse voltages. The pulse motor valve 23 is fully opened when the heating circuit is formed, and fully closed when the defrosting circuit described later is formed. The refrigerant flow to the exchanger 22 is blocked in the liquid side piping of the heat pump refrigeration cycle.

  In the heat pump refrigeration cycle having such a configuration, a check valve (from a liquid side pipe between the pulse motor valve 23 and the electric expansion valve 13 to a gas side pipe between the four-way valve 12 and the two-way valve 21 is provided. A bypass path 24 for forming a defrost circuit including a check valve 24a is connected.

  By switching the four-way valve 12, closing the two-way valve 21, and fully closing the pulse motor valve 23, the refrigerant discharged from the compressor 11 passes through the four-way valve 12 to the outdoor heat exchanger 14 as shown by the broken line arrows. A defrosting circuit is formed in which the refrigerant that flows directly and passes through the outdoor heat exchanger 14 is sucked into the compressor 11 through the electric expansion valve 13, the bypass path 24, and the four-way valve 12. By forming this defrosting circuit, frost attached to the outdoor heat exchanger 14 is removed by the heat of the high-temperature refrigerant supplied from the compressor 11.

  On the other hand, the hot water supply tank unit 30 has a hot water supply tank 31, and a water inlet pipe 41 and a water outlet pipe 42 are connected to the lower and upper parts of the hot water tank 31, respectively. The incoming water pipe 41 guides water from the water supply source to the lower part of the hot water supply tank 31. The outlet pipe 42 guides the hot water in the upper part of the hot water supply tank 31 to the load.

  A water inlet pipe 32 is connected from the lower part of the hot water supply tank 31 to one end of the water flow path of the water heat exchanger 22, and a water discharge pipe 33 is connected from the other end of the water flow path of the water heat exchanger 22 to the upper part of the hot water supply tank 31. The A circulation pump 27 for supplying water is provided in the incoming water pipe 32. By operating the circulation pump 27, hot water in the hot water supply tank 31 is circulated through the water heat exchanger 22.

  In the outdoor unit 10, a refrigerant temperature sensor 15 that detects the refrigerant temperature Td discharged from the compressor 11 is attached to a discharge side pipe between the discharge port of the compressor 11 and the four-way valve 12. A refrigerant temperature sensor 16 that detects an intake refrigerant temperature Ts to the compressor 11 is attached to a suction side pipe between the four-way valve 12 and the suction port of the compressor 11. In the vicinity of the outdoor heat exchanger 14, an outside air temperature sensor 17 that detects the outside air temperature To is disposed. A heat exchange temperature sensor 18 for detecting the heat exchanger temperature Te is attached to the outdoor heat exchanger 14.

  In the water heat exchanger unit 20, a heat exchanger temperature sensor 25 that detects the heat exchanger temperature Tc is attached to the water heat exchanger 22. A refrigerant temperature sensor 26 for detecting the refrigerant temperature Tx is attached to the liquid side pipe between the water heat exchanger 22 and the pulse motor valve 23. A water temperature sensor 28 for detecting the temperature Twi of hot water flowing into the water heat exchanger 22 is attached to the incoming water pipe 32. A water temperature sensor 29 for detecting the temperature Two of hot water flowing out from the water heat exchanger 22 is attached to the outlet pipe 33.

  In the hot water supply tank unit 30, an electric heater 34 for hot water heating is disposed in the hot water supply tank 31. A water temperature sensor 35 that detects the temperature Tt of hot water in the hot water supply tank 31 is attached to the lower part of the hot water supply tank 31.

  The control unit 50 includes a microcomputer and its peripheral circuits, and has a RAM (Random Access Memory) 52 which is a volatile memory as a storage means, and an electric field capacitor 53 as an operation power source for the RAM 52.

And the control part 50 has the following means (1)-(5) as main functions.
(1) The refrigerant discharged from the compressor 11 passes through the four-way valve 12, the two-way valve 21, the water heat exchanger 22, the pulse motor valve 23, the electric expansion valve 13, the outdoor heat exchanger 14, and the four-way valve 12. 11, the heating operation of operating the circulation pump 27 while forming the heating circuit, and the refrigerant discharged from the compressor 11 with the two-way valve 21 and the pulse motor valve 23 closed, the four-way valve 12, the outdoor heat exchanger 14, The 1st control means which performs selectively the defrost operation which forms the defrost circuit which returns to the compressor 11 through the electric expansion valve 13, the bypass path 24, and the four-way valve 12.

  (2) Second control means for operating the circulation pump 27 when the detected temperature Tx of the refrigerant temperature sensor 26 falls below a set value during the defrosting operation.

  (3) Third control means for controlling the rotational speed of the circulation pump 27 operated by the second control means in accordance with the detected temperature Tx of the refrigerant temperature sensor 26.

  (4) Fourth control means for correcting the rotational speed by the control of the third control means in accordance with the detected temperature Twi of the water temperature sensor 28.

  (5) During the defrosting operation, when the detected temperature tx of the refrigerant temperature sensor 26 falls below a predetermined value lower than the set value, the operation of the compressor 11 is interrupted and the pulse motor valve 23 is fully opened and fully opened. 5th control means which closes (initialization treatment) and restarts the driving | operation of the compressor 11 after this full closure.

Next, the operation will be described with reference to the flowchart of FIG.
When the load-side hot water tap is opened, the hot water existing in the upper part of the hot water supply tank 31 flows to the load through the outlet pipe 42. Along with this, water from the water supply source is supplied to the lower part of the hot water supply tank 31 through the water inlet pipe 41.

  When the temperature Tt of hot water in the hot water supply tank 31 is detected by the water temperature sensor 35 and the detected temperature Tt falls below the set temperature by the operation of the operation / display unit 51, the compressor 11 is activated to form a heating circuit. At the same time, the circulation pump 27 is operated. By the heating operation by the heating circuit and the circulation pump 27, the hot water in the hot water supply tank 31 is heated. When the heating progresses and the detected temperature Tt of the water temperature sensor 35 rises above the set temperature, the compressor 11 is stopped, the formation of the heating circuit is released, and the circulation pump 27 is stopped.

  If the outside air temperature is low during the heating operation, frost gradually adheres to the surface of the outdoor heat exchanger 14 that functions as an evaporator. With this frost formation, the temperature Te of the outdoor heat exchanger 14 decreases.

  The temperature Te of the outdoor heat exchanger 14 is detected by the heat exchanger temperature sensor 18, and the defrosting condition is established in which the detected temperature Te decreases to a set value (for example, 0 ° C.) or less and the state continues for a predetermined time. Then (YES in step 101), a defrosting circuit is formed, and a defrosting operation for the outdoor heat exchanger 14 is started (step 102).

  During this defrosting operation, the circulation pump 27 is stopped and the circulation of hot water to the water heat exchanger 22 is stopped, the two-way valve 21 is closed, and the pulse motor valve 23 is fully closed. That is, the pulse motor valve 23 is fully closed so that the refrigerant whose temperature has decreased due to defrosting in the outdoor heat exchanger 14 does not flow into the water heat exchanger 22. Further, in the defrosting circuit, there is a refrigerant flow toward the four-way valve 12 via the bypass passage 24, and a negative pressure is applied to the pulse motor valve 23 via the hydrothermal exchanger 22 while the two-way valve 21 remains open. Since the negative pressure may cause refrigerant leakage in the pulse motor valve 23, the two-way valve 21 is closed to prevent such a problem.

  However, when dust is caught in the pulse motor valve 23 or when the pulse number deviation occurs in the drive pulse voltage supply when the opening degree of the pulse motor valve 23 is controlled, the refrigerant flows from the pulse motor valve 23 that should be fully closed. May leak. In this case, the leaked refrigerant may flow into the water heat exchanger 22 and the water heat exchanger 22 may be frozen.

  In order to prevent such a problem, the circulation pump control based on the detected temperature Tx of the refrigerant temperature sensor 26 in the liquid side pipe between the pulse motor valve 23 and the water heat exchanger 22 is executed during the defrosting operation ( Step 200).

  In this circulation pump control, the temperature zone condition of FIG. 3 that defines the correspondence relationship between the detected temperature Tx of the refrigerant temperature sensor 26 and a plurality of zones a, b, c, d, e determined for the detected temperature Tx, 4 is used in which the rotational speed of the circulation pump 27 is determined for each zone.

  In the temperature zone condition of FIG. 3, a temperature difference (hysteresis) of 1K is secured between the zone boundary when the detected temperature Tx changes and the zone boundary when the detected temperature Tx changes. For example, when the detection temperature Tx rises, −25 ° C. is the boundary point from the e zone to the d zone, −5 ° C. is the boundary point from the d zone to the c zone, and 0 ° C. is from the c zone to the b zone. 10 ° C. becomes the boundary point from the b zone to the a zone. When the detected temperature Tx decreases, 9 ° C. becomes the boundary point from the a zone to the b zone, −1 ° C. becomes the boundary point from the b zone to the c zone, and −6 ° C. becomes the boundary point from the c zone to the d zone. The point becomes −26 ° C. as a boundary point from the d zone to the e zone.

  In other words, if the detected temperature Tx is in the zone a (YES in step 201), the rotational speed of the circulation pump 27 is set to zero based on the determination that no refrigerant leaks in the pulse motor valve 23 (step 201). 202).

  When the detected temperature Tx decreases to a zone b lower than the zone a (YES in step 203), the circulation pump 27 operates at a rotational speed of 1300 rpm under the judgment that a small amount of refrigerant leaks in the pulse motor valve 23. (Step 204). Due to the operation of the circulation pump 27, hot water in the hot water supply tank 31 flows into the water heat exchanger 22, and the temperature drop of the water heat exchanger 22 due to refrigerant leakage of the pulse motor valve 23 is suppressed.

  If the detected temperature Tx is lowered to the c zone lower than the b zone (YES in step 205), the circulation pump 27 is rotated at a rotational speed of 2600 rpm based on the judgment that the refrigerant leakage of the pulse motor valve 23 is larger than the small amount. Operation is performed (step 206). By increasing the number of rotations, the amount of hot water flowing to the water heat exchanger 22 is increased compared to the case of the b zone. Thereby, even if there is more refrigerant | coolant leakage of the pulse motor valve 23 than the said small amount, the temperature fall of the water heat exchanger 22 by it is suppressed.

  When the detected temperature Tx is lowered to the d zone lower than the c zone (YES in step 207), the circulation pump 27 is rotated at a rotation speed of 3420 rpm under the judgment that the refrigerant leakage of the pulse motor valve 23 is larger than the small amount. (Step 208). By increasing the rotational speed, the amount of hot water flowing to the water heat exchanger 22 becomes larger than that in the case of the c zone. Thereby, even if there is much refrigerant | coolant leak of the pulse motor valve 23, the temperature fall of the water heat exchanger 22 by it is suppressed.

  Thus, since the temperature fall of the water heat exchanger 22 can be suppressed, freezing of the water heat exchanger 22 can be prevented in advance. As a result, the hot water in the hot water supply tank 31 can be reliably heated, and the reliability as a hot water heater is improved.

  When the detected temperature Tx is lowered to e zone lower than d zone (NO in step 207), the operation of the compressor 11 is interrupted based on the judgment that the refrigerant leakage of the pulse motor valve 23 is considerably large, and the state Thus, an initialization process is performed in which the pulse motor valve 23 is once driven to fully open and then fully closed, and after the fully closed operation of the compressor 11 is resumed (step 209).

  If the cause of the refrigerant leakage of the pulse motor valve 23 is the dust trapped in the pulse motor valve 23, the dust is swept away when it is fully opened by the initialization process. By this flushing, the pulse motor valve 23 is reliably fully closed, and the refrigerant leakage is eliminated.

  If the refrigerant leakage of the pulse motor valve 23 is caused by a shift in the number of pulses of the drive pulse voltage supplied to the pulse motor valve 23, the pulse motor valve 23 is once driven to full open and then fully closed by initialization. This eliminates the deviation in the number of pulses of the drive pulse voltage supply. As a result, the subsequent pulse motor valve 23 is reliably fully closed, and the refrigerant leakage is eliminated.

  By eliminating the refrigerant leakage of the pulse motor valve 23, the water heat exchanger 22 can be prevented from freezing. As a result, the hot water in the hot water supply tank 31 can be reliably heated.

  On the other hand, when the circulation pump 27 is operated and the rotation speed is controlled, the temperature Twi of hot water flowing from the hot water supply tank 31 into the water heat exchanger 22 is detected by the water temperature sensor 28. Based on the detected temperature Twi, step 200 The rotational speed control value by the circulation pump control is corrected.

  In this correction, the temperature zone condition of FIG. 6 that defines the correspondence between the detected temperature Twi of the water temperature sensor 28 and a plurality of zones A and B determined for the detected temperature Twi, and the rotation speed for each zone. The rotation speed correction condition of FIG. 7 that defines the correction value is used.

  In the temperature zone condition of FIG. 6, a temperature difference (hysteresis) of 1K is ensured between the zone boundary when the detected temperature Twi changes and the zone boundary when the detected temperature Twi changes. For example, when the detected temperature Twi rises, 5 ° C. becomes the boundary point from the zone outside the Twi use range to the A zone, and 10 ° C. becomes the boundary point from the A zone to the B zone. When the detected temperature Twi changes, 9 ° C. becomes the boundary point from the B zone to the A zone, and 5 ° C. becomes the boundary point from the A zone to the zone outside the Twi use range.

  That is, if the detected temperature Twi is an A zone of less than 10 ° C. (YES in step 201), the rotation speed correction value is 1.0 times and the rotation speed control value is not corrected. When the detected temperature Twi exceeds 10 ° C. and enters the B zone (NO in step 201), the rotational speed correction value becomes 0.6 times. For example, when the rotational speed control value is 1300 rpm, the actual rotational speed of the circulation pump 27 is set to 780 rpm, which is 0.6 times. When the rotational speed control value is 2600 rpm, the actual rotational speed of the circulation pump 27 is set to 1560 rpm, which is 0.6 times. When the rotation speed control value is 3420 rpm, the actual rotation speed of the circulation pump 27 is set to 2052 rpm, which is 0.6 times.

  When the detected temperature Twi is higher than 10 ° C., the rotation of the circulation pump 27 is determined based on the determination that the temperature decrease of the water heat exchanger 22 can be suppressed even if the amount of hot water flowing into the water heat exchanger 22 is slightly reduced. The number is corrected in the reduction direction. By this correction, the power required for the operation of the circulation pump 27 can be reduced as much as possible, and an energy saving effect can be obtained.

  When the defrosting of the outdoor heat exchanger 14 proceeds and the detected temperature Te of the heat exchanger temperature sensor 18 exceeds a set value, for example, 8 ° C. (YES in step 212), the formation of the defrosting circuit is canceled and the defrosting operation is performed. End (step 103). With this termination, the heating operation is restarted appropriately according to the detected temperature Tt of the water temperature sensor 35.

[2] A second embodiment will be described.
The control unit 50 has the following means (6) and (7) in addition to the means (1) to (5) of the first embodiment.
(6) At least at the first transition from the heating operation to the defrosting operation, the pulse motor valve 23 is opened to a predetermined opening, for example, an opening for 100 pulses, and the circulation pump 27 is operated at a predetermined rotation speed, for example, 3420 rpm. Whether or not the refrigerant temperature sensor 26 is abnormal is checked based on the temperature detected by the temperature sensor 26, and if there is no abnormality, the defrosting operation is continued and the completion of the check is held in the RAM 52 as a check completion flag ON. If there is an abnormality, sixth control means for stopping all the operations including the defrosting operation (abnormal stop).

  (7) In the heating operation, when the RAM 52 holds that the check is completed (check completion flag ON), whether there is an abnormality in the refrigerant temperature sensor 26 based on the change in the detected temperature Tx of the refrigerant temperature sensor 26 A seventh control means for simply checking the contents of the RAM 52 (check completion flag ON) when there is no abnormality and retaining the contents of the RAM 52 (check completion flag ON) when there is an abnormality.

  The RAM 52 in the control unit 50 functions as a storage unit that holds the completion of the sensor abnormality check as a check completion flag ON. Further, the RAM 52 can retain the stored contents for about 12 hours by the remaining charge in the electric field capacitor 53 even when the power is cut off due to the power switch being turned off or the commercial AC power supply is instantaneously interrupted.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  As for the operation, as shown in the flowchart of FIG. 7, the sensor abnormality check control step 300 for checking whether or not the refrigerant temperature sensor 26 is abnormal between the step 102 of the defrosting operation start and the step 200 of the circulation pump control. Will be added.

  In other words, during the heating operation, when the temperature Te of the outdoor heat exchanger 14 detected by the heat exchanger temperature sensor 18 is lowered to a set value (for example, 0 ° C.) or less and the defrosting condition in which the state continues for a predetermined time is satisfied. (YES in step 101), a defrosting circuit is formed, and the defrosting operation for the outdoor heat exchanger 14 is started (step 102). Along with the start of the defrosting operation, sensor abnormality check control for checking whether or not the refrigerant temperature sensor 26 is abnormal is executed (step 300).

  First, it is monitored whether or not the check completion flag in the RAM 52 is on (step 301). If the heating operation is an operation immediately after the power switch is turned on or an operation immediately after the momentary power failure of the commercial AC power supply is canceled, and the time elapsed until the start is long, the residual charge of the electrolytic capacitor 53 disappears and the contents of the RAM 52 Is in an erased state. In this case, the check completion flag in the RAM 52 indicates an off state.

  If the check completion flag in the RAM 52 is off (NO in step 301), the pulse motor valve 23 is opened at a predetermined opening, for example, 100 pulses, based on the determination that it is the first transition from the heating operation to the defrosting operation. While being opened to the opening degree (step 302), the circulation pump 27 is activated and its rotation speed is set to a predetermined rotation speed, for example, 3420 rpm (step 303).

  The opening degree for 100 pulses is an opening degree that supplies 100 driving voltage pulses to the pulse motor valve 23 and passes a small amount of low-temperature refrigerant flowing out of the outdoor heat exchanger 14 through the pulse motor valve 23. . In order to suppress the temperature drop of the water heat exchanger 22 due to the flow of the low-temperature refrigerant at this time, the circulation pump 27 is activated and the circulation pump 27 is operated at a rotation speed of 3420 rpm, and the hot water in the hot water supply tank 31 is The water heat exchanger 22 is circulated.

  As the pulse motor valve 23 is opened for 100 pulses, it is determined whether or not the detected temperature Tx of the refrigerant temperature sensor 26 falls below, for example, −5 ° C., which is a set value for abnormality determination (step 304). . If the detected temperature Tx falls below −5 ° C. (YES in step 304), under the judgment that the refrigerant temperature sensor 26 is normal and under the judgment that the check on the refrigerant temperature sensor 26 is completed. The check completion flag of the RAM 52 is turned on (step 306).

  Even if the detected temperature Tx does not fall below −5 ° C. (NO in step 304), the current detected temperature Tx is lower than the detected temperature Tx0 of the refrigerant temperature sensor 26 before the start of the current defrosting, and the difference is 25K. If exceeded (YES in step 305), the check completion flag of the RAM 52 is turned on under the determination that the refrigerant temperature sensor 26 is normal and the determination that the check for the refrigerant temperature sensor 26 is completed. (Step 306).

  As the check completion flag is turned on, the circulation pump control accompanying the defrosting operation is executed (step 200). Since this circulation pump control is the same as that of the first embodiment, the description thereof is omitted.

  When the defrosting of the outdoor heat exchanger 14 proceeds and the detected temperature Te of the heat exchanger temperature sensor 18 exceeds a set value, for example, 8 ° C., the formation of the defrosting circuit is canceled and the defrosting operation is terminated (step 103). ). With this termination, the heating operation is restarted appropriately according to the detected temperature Tt of the water temperature sensor 35.

  When the defrosting condition is satisfied after the heating operation is resumed (YES in step 101), the second defrosting operation is started (step 102). At this time, since the check completion flag in the RAM 52 is on (YES in step 301), the circulation pump control is executed without executing the check process from step 302 (step 200).

  On the other hand, during the first defrosting operation, the detected temperature Tx does not drop below -5 ° C. (NO in step 304), or the current detected temperature Tx and the detected temperature Tx0 of the refrigerant temperature sensor 26 before the start of the current defrosting. When 3 minutes have elapsed since the start of the defrosting operation (YES in step 307) without the difference between -25K and -25K being exceeded (YES in step 305), it is determined that the refrigerant temperature sensor 26 is abnormal. Below, the compressor 11 is stopped, all the operations including the current defrosting operation are stopped (abnormal stop), and the fact of the stop is displayed on the operation / display unit 51 (step 308). As abnormality of the refrigerant temperature sensor 26, failure of the detection function of the refrigerant temperature sensor 26, failure of attachment of the refrigerant temperature sensor 26 to the piping due to vibration, etc., disconnection of a signal line for transmitting the detection signal of the refrigerant temperature sensor 26 and so on.

  The user of the water heater grasps the cause of the stoppage of all operations from the display on the operation / display unit 51 and requests maintenance such as inspection and repair from the manufacturer or the store. Until this maintenance is performed, the abnormally stopped state is maintained.

  Therefore, the defrosting operation does not continue with abnormality occurring in the refrigerant temperature sensor 26, and the freezing of the water heat exchanger 22 can be reliably prevented. As a result, the hot water in the hot water supply tank 31 can be reliably heated.

  Note that the detected temperature Tx does not decrease below −5 ° C. (NO in step 304), or the difference between the current detected temperature Tx and the detected temperature Tx0 of the refrigerant temperature sensor 26 before the start of the current defrosting is −25K. The defrosting of the outdoor heat exchanger 14 proceeds and the detection of the heat exchange temperature sensor 18 without exceeding (YES in Step 305) and without passing 3 minutes from the start of the defrosting operation (NO in Step 307). Temperature Te may exceed a set value, for example, 8 ° C. (YES in step 309). In this case, it is assumed that the check for the refrigerant temperature sensor 26 has not been completed yet and is on hold, and the OFF state of the check completion flag in the RAM 52 is continued (step 310). And formation of a defrost circuit is cancelled | released and a defrost operation is complete | finished (step 103). With this termination, the heating operation is restarted appropriately according to the detected temperature Tt of the water temperature sensor 35.

  When the defrosting operation is started again after the heating operation is restarted, the check completion flag in the RAM 52 is kept off (NO in step 301), and thus the check process from step 302 is repeated.

  By the way, the check completion flag ON of the RAM 52 is held for about 12 hours by the remaining charge of the electric field capacitor 53 regardless of the power switch OFF or the commercial AC power supply instantaneous power failure. Therefore, after the heating operation is started by turning on the power switch or releasing the instantaneous power failure (the compressor 11 is activated), if the check completion flag ON indicating the completion of the check is held in the RAM 52 Even if the defrosting operation is started, the check process is not executed, and an unexpected abnormality of the refrigerant temperature sensor 26 may be missed.

Therefore, in the sensor abnormality check control, during the heating operation (YES in step 311), if the check completion flag ON indicating the completion of the check is held in the RAM 52 (YES in step 312), the refrigerant temperature sensor 26 A simple check process is executed for.
That is, the temperature detected by the refrigerant temperature sensor 26 immediately after the start of the heating operation (immediately after the start of the compressor 11) (the temperature of the refrigerant flowing out of the water heat exchanger 22 and flowing toward the pulse motor valve 23) is Txa, and heating is performed. The detected temperature of the refrigerant temperature sensor 26 during operation (the temperature of the refrigerant that flows out of the water heat exchanger 22 and flows toward the pulse motor valve 23) is Txb, and the change in the detected temperature (= Txb−Txa) is 3K. (Step 313: YES), the refrigerant temperature sensor 26 keeps the check completion flag ON of the RAM 52 as it is under the judgment that the refrigerant temperature is properly captured and there is no abnormality (step 314). ).

  However, if the change in the detected temperature (= Txb−Txa) does not exceed 3K (YES in step 313) and a predetermined time, for example, 5 minutes continues from the start of the heating operation (YES in step 315), the refrigerant temperature The check completion flag ON of the RAM 52 is erased based on the determination that some abnormality that cannot properly capture the refrigerant temperature has occurred in the sensor 26 (step 316). That is, the check completion flag in the RAM 52 is turned off.

  When the check completion flag is turned off, when the heating operation is shifted to the defrosting operation, the check process from step 302 is executed to check whether the refrigerant temperature sensor 26 is abnormal.

  Therefore, even if an unexpected abnormality occurs in the refrigerant temperature sensor 26 during the heating operation, it can be reliably detected without missing it. Thereby, the reliability of the circulation pump control for preventing freezing of the water heat exchanger 22 is improved.

[3] Modifications In each of the above embodiments, three stages of 1300 rpm, 2600 rpm, and 3420 rpm are set as the rotation speed in the circulation pump control. However, the value of the rotation speed and the number of stages are not limited, and the capacity of the circulation pump 27, What is necessary is just to determine suitably according to the diameter of the inflow piping 32 or the outflow piping 33, the capacity | capacitance of the water heat exchanger 22, etc. FIG.

  In addition, each embodiment and the modification are presented as examples, and are not intended to limit the scope of the invention. The novel embodiments and modifications can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. In these embodiments and modifications, the scope of the invention is included in the gist, and is included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Outdoor unit, 11 ... Compressor, 12 ... Four-way valve, 13 ... Electric expansion valve, 14 ... Outdoor heat exchanger, 20 ... Hydrothermal exchange unit, 21 ... Two-way valve (open / close valve), 22 ... Water heat exchange 23 ... Pulse motor valve (open / close valve), 24 ... Bypass passage, 24a ... Check valve, 26 ... Refrigerant temperature sensor, 27 ... Circulating pump, 28 ... Water temperature sensor, 30 ... Hot water tank unit, 31 ... Hot water tank 32 ... Inlet piping, 33 ... Outlet piping, 41 ... Incoming piping, 42 ... Outlet piping, 50 ... Control section, 51 ... Operation / display section

Claims (5)

A hot water tank,
Connect a compressor, a four-way valve, a water heat exchanger, an on-off valve, a decompressor, and an outdoor heat exchanger in this order, and connect the pipe between the on-off valve and the decompressor between the four-way valve and the water heat exchanger. A heat pump refrigeration cycle having a bypass path over the piping;
A circulation pump for circulating hot water in the hot water tank through the water heat exchanger;
A refrigerant temperature sensor for detecting the temperature of the refrigerant passing through a pipe between the water heat exchanger and the on-off valve;
With the open / close valve closed, the refrigerant discharged from the compressor forms a defrosting circuit that returns to the compressor through the four-way valve, the outdoor heat exchanger, the decompressor, the bypass passage, and the four-way valve. Control means for operating the circulation pump when the frost operation is performed and the detected temperature of the refrigerant temperature sensor is lowered to a set value or less during the defrost operation,
A water heater characterized by comprising. The control means controls the number of rotations of the circulating pump to be operated according to the detected temperature of the refrigerant temperature sensor.
The water heater according to claim 1. A water temperature sensor for detecting the temperature of hot water flowing in the water heat exchanger;
Further comprising
The control means controls the rotational speed of the circulating pump to be operated according to the detected temperature of the refrigerant temperature sensor, and corrects the rotational speed by the control according to the detected temperature of the water temperature sensor.
The water heater according to claim 1. The on-off valve is a pulse motor valve whose opening degree changes continuously,
The control means interrupts the operation of the compressor and temporarily opens the pulse motor valve when the temperature detected by the refrigerant temperature sensor falls below a predetermined value lower than the set value during the defrosting operation. Fully closed, and after this fully closed operation of the compressor is resumed.
The water heater according to any one of claims 1 to 3, wherein the water heater is provided. The on-off valve is a pulse motor valve whose opening degree changes continuously,
The control means includes
The heating circuit in which the defrosting operation and the refrigerant discharged from the compressor return to the compressor through the four-way valve, the water heat exchanger, the on-off valve, the decompressor, the outdoor heat exchanger, and the four-way valve Means for selectively executing a heating operation for operating the circulation pump while forming
At least at the first transition from the heating operation to the defrosting operation, the refrigerant is opened based on the temperature detected by the refrigerant temperature sensor while opening the pulse motor valve to a predetermined opening and operating the circulation pump at a predetermined rotation speed. The temperature sensor is checked for abnormalities, and if there is no abnormality, the defrosting operation is continued and the completion of the check is held in the storage means. If there is an abnormality, all operations including the defrosting operation are performed. Means to stop
In the heating operation, if the storage means holds that the check is completed, the presence or absence of abnormality of the refrigerant temperature sensor is simply checked based on the change in temperature detected by the refrigerant temperature sensor, Means for holding the contents of the storage means as it is when there is none, and erasing the contents of the storage means when there is an abnormality,
including,
The water heater according to any one of claims 1 to 3, wherein the water heater is provided.

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