JP5840062B2 - Heat pump type liquid heating device and heat pump type water heater - Google Patents

Description

  The present invention relates to a heat pump type liquid heating device and a heat pump type hot water heater, and more particularly to control of a refrigeration cycle of the heat pump type liquid heating device and the heat pump type hot water heater.

  When refrigeration cycle control is performed in a heat pump type water heater equipped with a heat pump type liquid heating device, the target discharge pressure of the refrigerant from the compressor, and the discharge pressure (actual discharge pressure) from the compressor that is actually detected from the refrigeration cycle Is known, and a pressure reducing device (pressure reducing valve) is controlled so that the actual discharge pressure coincides with the target discharge pressure (for example, refer to Patent Document 1 described later).

  In such a control method, control based on the discharge pressure of the compressor is performed, and control based on the discharge temperature of the refrigerant from the compressor is not performed. For this reason, the refrigerant discharge temperature from the compressor may reach a temperature (hereinafter referred to as “maximum allowable temperature”) that affects the durability of the components of the refrigeration cycle including the compressor. . In order to avoid this, conventionally, before the discharge temperature of the compressor reaches the maximum allowable temperature, for example, an emergency measure such as reducing the rotation speed (rotation speed) of the compressor or opening the decompression device is used. Control is being performed.

  When the discharge temperature of the compressor reaches the maximum allowable temperature, for example, when the evaporator performance decreases due to frost on the evaporator, and the difference between the suction pressure and discharge pressure of the compressor increases, This may occur when the liquid to be heated is delivered at a high temperature (for example, 90 ° C.) when the outside air temperature is low (for example, 2 ° C.). More specifically, under such conditions, the target discharge pressure of the compressor is set near the design upper limit of the discharge temperature in order to improve the COP (Coefficient of Performance) of the refrigeration cycle. As a result, the discharge temperature of the refrigerant from the compressor may reach the maximum allowable temperature due to output variations for each product and changes in environmental conditions.

Japanese Patent No. 4465986

  However, if the emergency measures such as reducing the rotation speed (rotational speed) of the compressor or opening the decompression device are performed as in the above-described prior art, the output of the refrigeration cycle is reduced, which is essential. There is a problem that the delivery temperature of the liquid to be heated is temporarily reduced. In the heat pump type hot water heater, control is performed so that the COP is the highest in the refrigeration cycle and the supply temperature of the liquid to be heated is constant. If this is done, the control of the refrigeration cycle is temporarily disrupted, so that there is a problem that an inefficient state in which the liquid to be heated is not stable continues for a certain period of time and it takes time to return to a stable state.

  The present invention provides a heat pump type liquid heating device and a heat pump type hot water heater that can be stably operated even when the discharge temperature of the compressor may reach the maximum allowable temperature. Objective.

In order to solve the above-described problems and achieve the object, the present invention provides a compressor that compresses and discharges the sucked refrigerant, and heat exchange that performs heat exchange between the refrigerant discharged from the compressor and the liquid to be heated. A pressure reducing valve that decompresses the refrigerant flowing out of the heat exchanger, an evaporator that performs heat exchange between the refrigerant flowing out of the pressure reducing valve and air, and a temperature of the refrigerant discharged from the compressor Or temperature detecting means for detecting the temperature of the compressor, and control means for controlling the rotational speed of the compressor so that the temperature of the heated liquid coming out of the heat exchanger becomes a preset target value. The control means performs the opening degree control of the pressure reducing valve based on the discharge pressure of the compressor , and when the detected temperature detected by the temperature detecting means is equal to or higher than a predetermined reference temperature, Above Out not such to put the opening control of the pressure reducing valve based on the temperature, the predetermined temperature from said time when the temperature of the heated liquid has started opening control of the pressure reducing valve based on the detected temperature flowing into the heat exchanger In the heat pump type liquid heating apparatus, when the pressure increases, the opening control of the pressure reducing valve based on the detected temperature is canceled and the opening control of the pressure reducing valve based on the discharge pressure is performed .

  Moreover, this invention is provided with the said heat pump type liquid heating apparatus and the tank which stores the to-be-heated liquid heated with the said heat exchanger, It is a heat pump type hot water heater characterized by the above-mentioned.

  According to the heat pump type liquid heating device and the heat pump type water heater according to the present invention, even when the discharge temperature of the compressor may reach the maximum allowable temperature, the operation can be performed stably.

It is composition explanatory drawing of the heat pump type hot water supply machine concerning one Embodiment of this invention. It is a flowchart which shows the procedure of the opening degree control process of the pressure-reduction valve by a control part. It is a time chart which shows the timing which performs control based on a compressor discharge temperature in a heat pump type hot water heater.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the present embodiment, a heat pump type water heater provided with a heat pump type liquid heating device and using water as a liquid to be heated will be described as an example. In the heat pump type hot water supply apparatus according to the present embodiment, when the control unit (control unit) controls the refrigerant discharge pressure (compressor discharge pressure) to the high pressure side of the compressor to be the target value (target discharge pressure). Protect the compressor when the refrigerant discharge temperature (compressor discharge temperature) to the high pressure side of the compressor approaches the temperature (maximum allowable temperature) that impairs the durability of the components of the refrigeration cycle, including the compressor Therefore, before the pressure reducing valve is opened or the rotation speed (rotation speed) of the compressor is decreased, the compressor discharge temperature is controlled to be the target discharge temperature that is the target value. Below, after demonstrated the whole structure of the heat pump type water heater concerning this embodiment, and basic operation of a control part, operation of a control part concerning the present invention is explained still more concretely.

  FIG. 1 is a configuration explanatory diagram of a heat pump type water heater according to an embodiment of the present invention. As shown in FIG. 1, the heat pump type hot water heater S includes a heat pump unit (heat pump type liquid heating device) 1 and a tank unit 2. The heat pump unit 1 and the tank unit 2 may be separated from each other, or may be integrally disposed in one housing.

  The heat pump unit 1 is mainly configured by a compressor 3, a liquid refrigerant heat exchanger 4, a pressure reducing valve 5, an evaporator 6, and a control unit 50. The compressor 3, the liquid refrigerant heat exchanger 4, the pressure reducing valve 5, and the evaporator 6 are connected in a ring shape with piping so that the refrigerant circulates in this order. In the present embodiment, carbon dioxide, which is a refrigerant friendly to the natural environment, is used as the refrigerant. And in the heat pump part 1, since the discharge pressure of the refrigerant | coolant (carbon dioxide) by the compressor 3 uses the supercritical vapor compression refrigeration cycle which becomes more than the critical pressure of the said refrigerant | coolant, and a refrigerant | coolant can be made into high temperature / high pressure, for example, Hot water as high as 90 ° C. can be obtained.

  The compressor 3 compresses the refrigerant returned from the annular circuit, and sends the compressed high-temperature gas refrigerant (hereinafter sometimes referred to as hot gas) to the annular circuit again. More specifically, the compressor 3 sucks and compresses the refrigerant discharged from the evaporator 6 and discharges the refrigerant toward the liquid refrigerant heat exchanger 4.

  The capacity of the compressor 3 can be controlled, and when high-temperature hot water storage (for example, 90 ° C.) is performed, the compressor 3 is operated at a rotational speed (for example, 3000 to 4000 rotations / minute) faster than usual. Moreover, when driving | running by normal hot water storage temperature (for example, 65 degreeC), it drive | operates by a comparatively slow rotational speed (for example, 1000-2000 rotation / min). Further, the compressor 3 can control the rotation speed from a low speed (for example, 1000 rotations / minute) to a high speed (for example, 6000 rotations / minute) by PWM control, voltage control (for example, PAM control) and combination control thereof. It has become.

  A temperature sensor for detecting the temperature of the refrigerant discharged from the compressor 3 (compressor discharge temperature) on the compressor 3 side in a pipe connecting the compressor 3 and the liquid refrigerant heat exchanger 4 described below. 9 and a pressure sensor 8 for detecting the pressure of the refrigerant discharged from the compressor 3 (compressor discharge pressure). Instead of the temperature sensor 9 or together with the temperature sensor 9, a temperature sensor for detecting the temperature of the components of the compressor 3 may be provided. The component of the compressor 3 is a coil in the compressor 3, for example.

  The liquid refrigerant heat exchanger 4 (heat exchanger) functions as a condenser, and a refrigerant heat transfer tube 2a through which hot gas discharged from the compressor 3 circulates and a liquid through which water to be heated is circulated. And a heat transfer tube 2b. These refrigerant heat transfer tubes 2a and liquid heat transfer tubes 2b are provided in close contact so that the refrigerant and the liquid to be heated exchange heat with each other. Moreover, the flow of each heat exchanger tube is comprised so that it may oppose. In the liquid refrigerant heat exchanger 4, heat exchange between the refrigerant discharged from the compressor 3 and the liquid to be heated is performed.

  The pressure reducing valve 5 is provided in the middle of a pipe disposed between the liquid refrigerant heat exchanger 4 and the evaporator 6, and here, an electric expansion valve is used. The pressure reducing valve 5 depressurizes the medium temperature and high pressure refrigerant flowing out from the liquid refrigerant heat exchanger 4 and sends it to the evaporator 6 as a low pressure refrigerant that easily evaporates. The pressure reducing valve 5 can adjust the throttle opening (opening / closing degree), and the control unit 50 changes the throttle opening to adjust the refrigerant circulation amount in the heat pump unit 1. And the control part 50 will adjust the discharge pressure (compressor discharge pressure) of the compressor 3 by changing the throttle opening degree of the pressure-reduction valve 5, so that it may mention later. In addition, when the control part 50 forms frost on the evaporator 6, in order to melt the frost attached to the evaporator 6, the decompression valve 5 is opened (throttle opening is fully opened) and the defrost operation is performed.

  The evaporator 6 takes in outside air by rotation of the blower 7 and pumps heat from outside air by exchanging heat between the refrigerant circulating in the evaporator 6 and outside air (air blowing). That is, the evaporator 6 performs heat exchange between the refrigerant flowing out of the pressure reducing valve 5 and the air. The refrigerant that has passed through the evaporator 6 is returned to the compressor 3 again. The blower 7 is controlled to rotate at a predetermined rotational speed (rotational speed) command value.

  The temperature sensor 10 detects the temperature of the refrigerant on the downstream side of the evaporator 6. The controller 50 determines whether or not to perform defrosting in the evaporator 6 based on the temperature detected by the temperature sensor 10, and fully opens the pressure reducing valve 5 when performing defrosting. Reference numeral 14 denotes a temperature sensor that detects the outside air temperature. In the present embodiment, the temperature sensor 14 is provided in the vicinity of the blower 7.

  Reference numeral 36 is a delivery pipe, and one end of the delivery pipe 36 is connected to the outlet of the liquid heat transfer tube 2 b of the liquid refrigerant heat exchanger 4. The delivery pipe 36 feeds the liquid to be heated heated by the refrigerant from the liquid refrigerant heat exchanger 4 to the tank unit 2. More specifically, the delivery pipe 36 extends toward the tank 16 side of the tank unit 2 described later, and is connected to the upper part of the tank 16. Near the liquid refrigerant heat exchanger 4 of the delivery pipe 36, a temperature sensor 12 is provided that detects the temperature of the liquid to be heated that exits from the liquid refrigerant heat exchanger 4 (the water discharge temperature in the present embodiment).

  Reference numeral 35 denotes a supply pipe. The supply pipe 35 supplies the liquid to be heated heated by the refrigerant to the liquid refrigerant heat exchanger 4. One end of the supply pipe 35 is connected to the inlet of the liquid heat transfer tube 2 b of the liquid refrigerant heat exchanger 4. The supply pipe 35 extends toward the tank 16 described later, and is connected to the bottom of the tank 16. On the liquid refrigerant heat exchanger 4 side of the supply pipe 35, a temperature sensor 11 for detecting the temperature of the heated liquid entering the liquid refrigerant heat exchanger 4 (incoming water temperature in the present embodiment) is provided. As will be described later, the control unit 50 determines the target value of the compressor discharge pressure using the detected value of the temperature sensor 11 as one of the reference elements.

  Further, the pump 13 is disposed in the supply pipe 35 on the upstream side of the liquid refrigerant heat exchanger 4. The pump 13 is driven so as to send the liquid to be heated from the tank 16 described later to the inlet side of the liquid heat transfer tube 2b. The pump 13 is configured so that the flow rate (mass flow rate), flow rate, and pressure of circulating water can be freely selected.

  The tank unit 2 includes a tank 16 that stores a liquid to be heated (water in the present embodiment). The tank 16 is connected to one end of a delivery pipe 36 and a supply pipe 35 extending from the heat pump unit 1 side. The tank 16 is also connected to one end of the hot water supply pipe 38b and the water supply pipe 38a. A hot water supply port (not shown) is provided at the other end of the hot water supply pipe 38b. A water supply port (not shown) is provided at the other end of the water supply pipe 38a.

  The water supply pipe 38a is connected to a branch pipe 38c that branches from the water supply pipe 38a on the upstream side of the tank 16 and that joins the hot water supply pipe 38b at the tip thereof. The branch pipe 38 c is connected to the hot water supply pipe 38 b through the hot water / mixing valve 17. The hot water mixing valve 17 adjusts the amount of water flowing into the hot water supply pipe 38b via the water supply pipe 38a and the branch pipe 38c according to the degree of opening thereof, thereby providing a hot water supply port provided at the other end of the hot water supply pipe 38b (illustrated). (Omitted) Adjust the temperature of the hot water coming out.

  In the present embodiment, the liquid to be heated is once taken into the tank 16 and then supplied to the heat pump unit 1 via the supply pipe 35. However, the present invention is not limited to this. For example, the heat pump is directly supplied from a water supply port (water supply pipe). The heated liquid may be supplied to the unit 1. Further, in the present embodiment, the liquid to be heated heated by the heat pump unit 1 is once taken into the tank 16 and then supplied from the hot water supply port via the hot water supply pipe 38b. You may make it supply the to-be-heated liquid heated with the heat pump part 1 directly from the hot water supply port. Furthermore, instead of supplying hot water in the tank 16, it may be water direct pressure hot water provided with a heat exchanger that heats tap water using the heat of the hot water in the tank 16.

  The control unit 50 includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like, and comprehensively controls the heat pump type water heater S according to the present embodiment in accordance with a program stored therein. To do. For example, as described above, the control unit 50 defrosts the evaporator 6 based on the temperature detected by the temperature sensor 10 (the outlet refrigerant temperature of the evaporator 6). In addition, the control unit 50 determines the target discharge pressure of the compressor 3 and the compressor 3 according to the procedure described later based on the temperature detected by the temperature sensors 9, 11, 12, and 14, the pressure detected by the pressure sensor 8, and the like. The target discharge temperature is calculated, and the rotational speed of the compressor 3 and the opening of the pressure reducing valve 5 are controlled based on the detected value (actually measured value) and the target value.

  Next, the operation of the heat pump type water heater S will be described. In the heat pump water heater S, when the boiling operation is performed at midnight power, the hot water in the tank 16 is almost used up, and in this case, the tank 16 is filled with cold water (normal temperature water). Alternatively, hot water may remain at the top of the tank 16.

  Normally, the tank 16 is always full of water, and in this state, the heat pump type hot water heater S performs a hot water storage operation process. The heat pump type water heater S sends hot gas discharged from the started compressor 3 into the refrigerant heat transfer tube 2 a of the liquid refrigerant heat exchanger 4. The hot gas sent into the refrigerant heat transfer tube 2a is condensed by releasing heat into the water in the liquid heat transfer tube 2b. And the water in the liquid heat exchanger tube 2b is heated with hot gas. Next, the refrigerant sent out from the refrigerant heat transfer tube 2 a of the liquid refrigerant heat exchanger 4 is depressurized by the pressure reducing valve 5 (expansion valve) and then flows into the evaporator 6. The refrigerant flowing into the evaporator 6 pumps up heat from the outside air via the liquid refrigerant heat exchanger 4 when evaporating with the wind sent from the blower 7. Thereafter, the refrigerant returns to the compressor 3 and is compressed again.

  On the other hand, the water filled in the tank 16 is sent into the liquid heat transfer pipe 2 b of the liquid refrigerant heat exchanger 4 from the bottom of the tank 16 through the supply pipe 35 when the pump 13 is activated. As described above, the water sent into the liquid heat transfer tube 2b is heated by heat exchange with the refrigerant to become hot water and flows into the delivery pipe 36. The hot water that has flowed into the delivery pipe 36 returns to the top of the tank 16 and is stored. Since the hot water returned to the top of the tank 16 has a low density, it does not mix with the cold water at the bottom of the tank 16 and accumulates in order from the top. Thus, while water circulates between the tank 16 and the liquid refrigerant heat exchanger 4, the heat pump hot water heater S secures a predetermined amount of hot water in the tank 16 at a predetermined temperature.

  The control unit 50 of the heat pump type hot water heater S controls the compressor 3, the pump 13, and the pressure reducing valve 5 as follows. The control unit 50 controls the rotational speed of the compressor 3 based on the outlet temperature of the liquid refrigerant heat exchanger 4 detected by the temperature sensor 12. Specifically, the control unit 50 controls the rotation speed of the compressor 3 so that the temperature detected by the temperature sensor 12 becomes a target value of the preset water discharge temperature. That is, when the detected value of the temperature sensor 12 is lower than the target value, the rotational speed of the compressor 3 is increased. Conversely, when the detected value is high, the rotational speed of the compressor 3 is decreased.

  Further, the control unit 50 controls the amount of water that the pump 13 sends to the liquid heat transfer tube 2b of the liquid refrigerant heat exchanger 4 based on the target rotational speed of the compressor 3 that has been obtained in advance in order to control the heating capacity. To do. Specifically, when the actual rotational speed is slower than the target rotational speed of the compressor 3, the pump 13 is controlled so that the amount of water fed into the liquid heat transfer tube 2b is increased, and compression is performed in reverse. When the actual rotational speed of the machine 3 is fast, the pump 13 is controlled so that the amount of water fed into the liquid heat transfer tube 2b is reduced. Thereby, a heating capability can be adjusted to target value (for example, 4.5 kW).

  The target rotational speed of the compressor 3 described above includes the target value of the water temperature of the liquid refrigerant heat exchanger 4, the target heating capacity (output) of the heat pump unit 1, and the detected value of the temperature sensor 14 (outside air temperature). ) And the detection value (incoming water temperature) of the temperature sensor 11 can also be set. Specifically, for example, as described above, the target rotational speed of the compressor 3 is set in a range of 3000 to 4000 revolutions / minute when performing high-temperature hot water storage (for example, 90 ° C.). In the case of operating at a temperature (for example, 65 ° C.), the speed is set in a range of 1000 to 2000 revolutions / minute, but is not limited thereto.

  Further, the controller 50 controls the opening degree of the pressure reducing valve 5 based on the discharge pressure of the compressor 3. That is, the control unit 50 controls the opening of the pressure reducing valve 5 so that the compressor discharge pressure becomes a target value calculated in advance by the control unit 50. Specifically, when the pressure detected by the pressure sensor 8 is higher than the target discharge pressure, the pressure reducing valve is opened, and when it is low, the pressure reducing valve is closed. In addition to the target value of the outlet temperature of the liquid refrigerant heat exchanger 4, the target discharge pressure is determined by the control unit 50, the target heating capacity (output) of the heat pump unit 1, the detection value (outside temperature) of the temperature sensor 14, It is also possible to calculate and set based on the detected value (incoming water temperature) of the temperature sensor 11. The target discharge pressure is set so that the COP of the heat pump unit 1 is maximized, but is not limited thereto.

  Here, the opening degree control of the pressure reducing valve 5 by the control unit 50 is performed not only on the detection pressure (compressor discharge pressure) of the pressure sensor 8 but also on the detection value (detection temperature: compressor discharge temperature) of the temperature sensor 9. Sometimes it is done on the basis of. Although details will be described later, when the compressor discharge temperature is equal to or higher than a predetermined reference temperature, the control unit 50 controls the opening of the pressure reducing valve 5 based on the compressor discharge temperature. The opening degree control of the pressure reducing valve 5 based on the compressor discharge temperature is control for adjusting the opening degree of the pressure reducing valve 5 so that the compressor discharge temperature becomes the target discharge temperature. For example, the compressor discharge temperature is a predetermined value. When the pressure is higher than the target discharge temperature, the pressure reducing valve 5 is opened, and when the compressor discharge temperature becomes lower than the target discharge temperature, the pressure reducing valve 5 is closed. The target discharge temperature is a target value of the compressor discharge temperature calculated in advance by the control unit 50 as described above. When the opening degree control of the pressure reducing valve 5 based on the compressor discharge temperature is started, this control is continued until the operating condition of the refrigeration cycle of the heat pump unit 1 is changed.

  Next, the operation of the control unit 50 according to the present invention will be described. The control unit 50 changes the opening degree control method of the pressure reducing valve 5 according to the procedure shown in FIG. In particular, as shown in steps S3 and S4 in FIG. 2, when the compressor discharge temperature reaches the reference temperature, the control unit 50 controls the opening of the pressure reducing valve 5 based on the compressor discharge temperature to discharge the compressor. Ensure that the temperature does not reach the maximum allowable temperature. Here, the reference temperature is a temperature higher than the target temperature of the liquid to be heated after heat exchange in the liquid refrigerant heat exchanger 4, and is, for example, a maximum allowable temperature (eg, 130 ° C.) for maintaining the product life of the compressor 3. 3) to 15 ° C. (for example, 120 ° C.), but is not limited thereto.

  FIG. 2 is a flowchart showing the procedure of the opening degree control process of the pressure reducing valve by the control unit. In the flowchart of FIG. 2, first, when the heat pump unit 1 is started, the control unit 50 calculates a target discharge pressure (step S1). The controller 50 controls the opening of the pressure reducing valve 5 so that the detected pressure (compressor discharge pressure) of the pressure sensor 8 becomes the target discharge pressure (step S2). That is, Steps S1 and S2 are processing of the normal pressure reducing valve opening degree control (the opening degree control of the pressure reducing valve 5 based on the compressor discharge pressure).

  Next, the control unit 50 determines whether or not the detected value (compressor discharge temperature) of the temperature sensor 9 is equal to or higher than the reference temperature (step S3). When the compressor discharge temperature is lower than the reference temperature (step S3: No), the control unit 50 returns to step S2 and controls the opening degree of the pressure reducing valve 5 based on the compressor discharge pressure (hereinafter referred to as “compressor discharge pressure”). (Also called “control”).

  On the other hand, when the detected value (compressor discharge temperature) of the temperature sensor 9 is equal to or higher than the reference temperature (step S3: Yes), the control unit 50 cancels the control based on the compressor discharge pressure and sets the compressor discharge temperature. Based on the opening degree control of the pressure reducing valve 5 (hereinafter also referred to as “control based on the compressor discharge temperature”), the command rotational speed (rotational speed) of the blower 7 at that time, and the detected value of the temperature sensor 11 ( (Incoming water temperature) is stored (step S4). The command rotational speed (command rotational speed) of the blower 7 stored in step S4 and the detected value (incoming water temperature) of the temperature sensor 11 are the command rotational speed (command) of the blower 7 at the time when control based on the compressor discharge temperature is started. Rotation speed) and a detected value (incoming water temperature) of the temperature sensor 11.

  Next, the control unit 50 compares the detected value (incoming water temperature) of the current temperature sensor 11 with the detected value of the temperature sensor 11 stored in step S4, and determines whether or not there is a change over a predetermined temperature. Judgment is made (step S5). That is, in step S5, it is determined whether or not the detected value (incoming water temperature) of the temperature sensor 11 has changed by a predetermined temperature or more since the start of control based on the compressor discharge temperature. At this time, as the amount of change in the detection value (predetermined temperature), for example, a value set in advance such as ± 5 ° C. or more from the value stored in step S4 may be used. Further, the amount of change in the detected value of the temperature sensor 11 may be different between the rising side and the descending side, such as “+ 7 ° C. or higher or −5 ° C. or higher”. When the detected value has changed by a predetermined temperature or more (step S5: Yes), the control unit 50 proceeds to step S9, cancels the control based on the compressor discharge temperature (step S9), and returns to step S2. The control based on the compressor discharge pressure is performed.

  On the other hand, when the detected value of the temperature sensor 11 does not change more than the predetermined temperature in step S5 (step S5: No), the control unit 50 stores the command rotational speed (command rotational speed) of the blower 7 in step S4. It is determined whether or not the value has changed (step S6), whether or not operation stop of the heat pump unit 1 has been instructed (step S7), and whether or not the defrost operation is performed in the heat pump unit 1 (step S8). When the command rotational speed (command rotational speed) of the blower 7 is changed from the value stored in Step S4 (Step S6: Yes), or when the operation stop of the heat pump unit 1 is instructed (Step S7: Yes), or the heat pump When the defrost operation is performed in the unit 1 (step S8: Yes), the control unit 50 proceeds to step S9, cancels the control based on the compressor discharge temperature (step S9), returns to step S2, and returns to the compressor. Control based on discharge pressure.

  Here, steps S <b> 5 to S <b> 8 are for determining whether or not there has been a change in the operating conditions of the refrigeration cycle of the heat pump unit 1. If the operating conditions of the refrigeration cycle change, the discharge temperature of the compressor may be lowered without opening the pressure reducing valve 5, while the control currently being performed extremely reduces the COP of the refrigeration cycle. there is a possibility. For this reason, when there is a change in the operating condition of the refrigeration cycle of the heat pump unit 1, the control unit 50 cancels the opening degree control of the pressure reducing valve 5 based on the compressor discharge temperature, and based on the compressor discharge pressure. The opening degree control of the pressure reducing valve 5 (normal pressure reducing valve opening degree control) is performed.

  On the other hand, the command rotational speed of the blower 7 is not changed from the value stored in step S4 (step S6: No), the operation stop of the heat pump unit 1 is not instructed (step S7: No), and the heat pump unit 1 is defrosted. When the operation is not performed (step S8: No), the control unit 50 returns to step S5 and continues the control based on the compressor discharge temperature.

  Note that, after step S4, the compressor discharge temperature is not monitored, and only the operating conditions of the refrigeration cycle are monitored. Even if the compressor discharge temperature falls below the reference temperature due to the opening degree control of the pressure reducing valve 5 based on the compressor discharge temperature, the opening degree control of the pressure reducing valve 5 is immediately reduced to the normal pressure reducing valve opening degree control ( This is because returning to the control of the opening of the pressure reducing valve 5 based on the compressor discharge pressure) may cause the compressor discharge temperature to exceed the reference temperature again relatively quickly.

  As described above, in the heat pump type hot water heater S according to the present embodiment, by repeating the operation as shown in FIG. 2, the sudden decrease in the hot water temperature of the heat pump unit 1 and the cycle operation become unstable. To prevent. In addition, when a change occurs in the operating conditions of the refrigeration cycle and it is predicted that control based on the compressor discharge temperature will lead to a decrease in the COP of the refrigeration cycle, the opening control of the pressure reducing valve 5 based on the compressor discharge temperature is performed. The opening degree control of the pressure reducing valve 5 based on the compressor discharge pressure (normal pressure reducing valve opening degree control) is performed.

  In addition, in the heat pump type hot water heater S according to the present embodiment, when the increase in the compressor discharge temperature cannot be suppressed even if the above-described operation is performed, the pressure reducing valve 5 is forcibly opened as in the related art. Alternatively, an operation such as reducing the rotational speed (rotational speed) of the compressor 3 is performed.

  FIG. 3 is a time chart showing the timing of performing control based on the compressor discharge temperature in the heat pump hot water heater S. FIG. 3 shows the detection value of the temperature sensor 9 (compressor discharge temperature) and the detection value of the temperature sensor 11 (incoming water temperature). In FIG. 3, the horizontal axis represents the elapsed time t from the start of the heat pump type hot water heater S from the left side to the right side, and the vertical axis represents the compressor discharge temperature and the incoming water temperature.

  Moreover, time t1 has shown the time when the compressor discharge temperature rose and reached | attained predetermined predetermined reference temperature (S3: Yes of FIG. 2). Time t2 indicates the time when the incoming water temperature has increased by ΔTw compared to the stored value (detected value at time t1) (S5: Yes in FIG. 2). In other words, ΔTw represents the temperature difference between the detected value of the temperature sensor 11 at time t1 when control based on the compressor discharge temperature is started and the detected value of the temperature sensor 11 at time t2.

  3 will be described in more detail. At time 0, the control unit 50 calculates the target discharge pressure (S1 in FIG. 2), and the pressure detected by the pressure sensor 8 (compressor discharge pressure) becomes the target discharge pressure. Thus, the opening degree control of the pressure reducing valve 5 is started (S2 in FIG. 2). Thereby, the detection value (compressor discharge pressure) of the pressure sensor 8 and the detection value (compressor discharge temperature) of the temperature sensor 9 rise with time (time 0 to t1). Next, at time t1, the detection value (compressor discharge temperature) of the temperature sensor 9 becomes a predetermined reference temperature due to a decrease in the detection value (outside temperature) of the temperature sensor 14 or frosting of the evaporator 6 or the like. To reach.

  When the detected value (compressor discharge temperature) of the temperature sensor 9 reaches a predetermined reference temperature (S3: Yes in FIG. 2), the control unit 50 cancels the control based on the compressor discharge pressure and performs compression. The opening of the pressure reducing valve 5 is controlled based on the machine discharge temperature. Thereafter, when the tank unit 2 is filled with hot water, the temperature of water supplied to the heat pump unit 1 (incoming water temperature) increases. In addition, the detection value (compressor discharge temperature) of the temperature sensor 9 changes between time t1 and t2 so that it may become the target discharge temperature calculated beforehand.

  The control unit 50 constantly compares the detected value (stored value) of the temperature sensor 11 at the start of control based on the compressor discharge temperature with the current detected value of the temperature sensor 11. That is, after time t1, the detected value (stored value) of temperature sensor 11 at time t1 is compared with the detected value of temperature sensor 11 at that time (S5 in FIG. 2). When the detected value of the current temperature sensor 11 rises by ΔTw with respect to the stored value (time t2, S5 in FIG. 2: Yes), the control unit 50 cancels the opening degree control of the pressure reducing valve 5 based on the compressor discharge temperature. (S9 in FIG. 2), the opening degree of the pressure reducing valve 5 is controlled based on the compressor discharge pressure (S2 in FIG. 2). ΔTw is a preset value, and is the amount of change in the incoming water temperature at which the COP of the refrigeration cycle is expected to decrease by controlling the opening of the pressure reducing valve 5 based on the compressor discharge temperature. In the present embodiment, ΔTw is set to 5 ° C., for example.

  As described above, according to the heat pump type hot water heater S according to the present embodiment, when there is a possibility that the discharge temperature of the compressor may reach the maximum allowable temperature, the rotation speed (rotation speed) of the compressor 3 is set. Instead of performing emergency measures such as reducing the pressure or opening the pressure reducing valve 5 rapidly, the opening of the pressure reducing valve 5 is controlled based on the compressor discharge temperature. Thereby, it is possible to operate stably without giving a sudden state change to the refrigeration cycle.

  Further, according to the heat pump hot water supply apparatus S according to the present embodiment, when the operating condition of the refrigeration cycle in the own apparatus has changed, the opening degree control of the pressure reducing valve 5 based on the compressor discharge temperature is canceled. This is currently done while there is a possibility that the compressor discharge temperature may be lowered without performing the opening degree control of the pressure reducing valve 5 based on the compressor discharge temperature when the operating condition of the refrigeration cycle changes. This is because the opening degree control of the pressure reducing valve 5 based on the discharge temperature of the compressor may extremely reduce the COP of the refrigeration cycle. In the heat pump type water heater S, when the operating condition of the refrigeration cycle changes, the opening control of the pressure reducing valve 5 based on the discharge temperature of the compressor is canceled, so that the COP of the refrigeration cycle is prevented from being extremely lowered. can do.

  In this embodiment, the opening control of the pressure reducing valve 5 is performed using the refrigerant discharge temperature from the compressor 3 (detected value of the temperature sensor 9), that is, the compressor discharge temperature, but the temperature sensor 9 is used instead. Or a temperature sensor for detecting the temperature of the component parts of the compressor 3 together with the temperature sensor 9, the opening degree of the pressure reducing valve 5 using the temperature of the component parts of the compressor 3 (compressor temperature). Control may be performed. In this case, “compressor discharge temperature” in the above description may be read as “compressor temperature”.

  Moreover, although the tap water supplied via the water supply pipe from the water supply source was described as an example of the “heated liquid” of the present invention, the present invention is not limited to this example. As the “heated liquid” of the present invention, for example, well water may be employed. In addition to water, a liquid containing a latent heat storage material, brine, antifreeze liquid, or the like may be employed as the “heated liquid” in the present invention.

  The present invention is also applicable to an air conditioner that performs air conditioning (heating / air heating operation) using the liquid to be heated heated by the liquid refrigerant heat exchanger 4 (heat exchanger) in addition to the heat pump type water heater. can do.

1 Heat pump (heat pump type liquid heating device)
2 Tank part 3 Compressor 4 Liquid refrigerant heat exchanger (heat exchanger)
5 Pressure reducing valve 6 Evaporator 7 Blower 8 Pressure sensor 9 Temperature sensor (temperature detection means)
10, 11, 12, 14 Temperature sensor 16 Tank 50 Control unit (control means)
S Heat pump water heater

Claims (6)

A compressor for compressing and discharging the sucked refrigerant;
A heat exchanger that performs heat exchange between the refrigerant discharged from the compressor and the liquid to be heated;
A pressure reducing valve for depressurizing the refrigerant flowing out of the heat exchanger;
An evaporator that performs heat exchange between the refrigerant flowing out of the pressure reducing valve and air;
Temperature detecting means for detecting the temperature of the refrigerant discharged from the compressor or the temperature of the compressor;
Control means for controlling the rotational speed of the compressor so that the temperature of the heated liquid coming out of the heat exchanger becomes a preset target value;
The control means controls the opening degree of the pressure reducing valve based on the discharge pressure of the compressor , and when the detected temperature detected by the temperature detecting means is equal to or higher than a predetermined reference temperature, the detected temperature is set to the detected temperature. based not such to put the opening control of the pressure reducing valve,
When the temperature of the heated liquid flowing into the heat exchanger increases by a predetermined temperature or more from the time when the opening control of the pressure reducing valve based on the detected temperature is started, the opening degree control of the pressure reducing valve based on the detected temperature The heat pump type liquid heating apparatus is characterized in that the opening of the pressure reducing valve is controlled based on the discharge pressure . The control means cancels the opening control of the pressure reducing valve based on the detected temperature when the defrost operation is performed to open the pressure reducing valve in order to melt the frost attached to the evaporator, and the discharge pressure The heat pump type liquid heating apparatus according to claim 1 , wherein the opening degree of the pressure reducing valve is controlled based on the pressure. When the operation stop of the heat pump liquid heating device is instructed, the control means cancels the opening control of the pressure reducing valve based on the detected temperature and performs the opening control of the pressure reducing valve based on the discharge pressure. The heat pump type liquid heating apparatus according to claim 1 or 2 . The evaporator is provided with a blower,
Wherein the control means acquires the rotational speed command value information of the blower, when said rotational speed command value is changed from the time of starting the opening control of the pressure reducing valve based on the detected temperature based on the detected temperature the The heat pump type liquid heating apparatus according to any one of claims 1 to 3 , wherein the opening degree control of the pressure reducing valve is performed based on the discharge pressure by releasing the opening degree control of the pressure reducing valve. Using carbon dioxide as the refrigerant, any one of the claims 1-4 in which discharge pressure of the refrigerant by the compressor is characterized by using a refrigerating cycle of the supercritical vapor compression equal to or greater than the critical pressure of the refrigerant The heat pump type liquid heating device described in 1. The heat pump type liquid heating apparatus according to any one of claims 1 to 5 ,
A heat pump type water heater comprising a tank for storing a liquid to be heated to be heated by the heat exchanger.

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