WO2006006578A1 - Heat pump-type hot-water supply device - Google Patents

Abstract

At least at the time of starting a heat pump cycle, a high-pressure side target pressure (Pt) is set, a high-pressure side refrigerant pressure is controlled so as to be the target pressure (Pt), a temperature difference (ΔT1) between a target temperature-difference (ΔTt) and an actual temperature-difference (ΔT) is calculated, and the target pressure (Pt) is corrected so that the temperature difference (ΔT1) is not more than a predetermined value. By this, pressure reduction means (3, 30) are directly controlled by a high pressure-value detected by a pressure sensor etc. having high response, so that the stability of a heat pump cycle against variation of the cycle caused by an external factor can be improved. Further, because values detected by the pressure sensor varies greatly to make it difficult to achieve a target COP, the target pressure (Pt) is corrected using the actual temperature-difference (ΔT) detected by a temperature sensor etc. having less variation in detection values, and this enables to achieve the target COP.

Description

 Specification

 Heat pump water heater

 Technical field

 [0001] The present invention relates to a heat pump type water heater using a heat pump cycle as a means for heating hot water, and more particularly to a method for controlling a pressure reducing means during a boiling operation.

 Background art

 [0002] As a prior art, the present applicant has previously disclosed a technique disclosed in Japanese Patent Laid-Open No. 2000-213806. This is because the temperature of refrigerant flowing out of a gas cooler (heat radiator) that heats hot water to improve the coefficient of performance (hereinafter abbreviated as COP) in a heat pump water heater and the temperature of hot water flowing into the gas cooler The refrigerant pressure on the high pressure side is controlled by the decompression means so that the temperature difference ΔΤ of the above becomes the predetermined temperature difference ΔΤο.

 [0003] However, if the heat pump cycle changes due to external factors such as the frost of the evaporator during operation or the change in the amount of heat pump circulating water due to the user's hot water from the hot water storage tank, the temperature is detected. Response thermistor response delay The control delay of the decompression means occurs, and the stability of the cycle is lost and the possibility of an error stop increases.

 [0004] The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a heat pump type water heater having high cycle stability against external factors. Disclosure of the invention

In order to achieve the above object, the present invention employs the technical means described in claims 1 to 4. That is, in the invention described in claim 1, the hot water heater for heating hot water in a vapor compression heat pump cycle that moves the heat on the low temperature side to the high temperature side, the compressor (1) for sucking and compressing the refrigerant Heat exchange between the refrigerant discharged from the compressor (1) and the hot water supply water, and the radiator (2) configured so that the refrigerant flow and the hot water supply flow face each other, and outflow from the radiator (2) Pressure reducing means (3, 30) and pressure reducing means (3, 30) force to evaporate the flowing refrigerant and absorb the heat, and at the suction side of the compressor (1) When the refrigerant pressure on the high-pressure side is lower than the predetermined pressure, the refrigerant flowing out of the radiator (2) and the hot water supply water flowing into the radiator (2) The heat pump type water heater that controls the refrigerant pressure on the high-pressure side so that the actual temperature difference (ΔT) becomes the predetermined target temperature difference (ΔTt),

 At least at the start of the heat pump cycle, the target pressure (Pt) on the high pressure side is set, the refrigerant pressure on the high pressure side is controlled so as to be the target pressure (Pt), and the target temperature difference (Δ Τ and actual temperature difference (Δ T ), And the target pressure (Pt) is corrected so that the temperature difference (ΔT1) is less than or equal to a predetermined value.

 [0006] According to the invention described in claim 1, by controlling the pressure reducing means (3, 30) directly by the high pressure value detected from the response level, the pressure sensor, etc., the external factor causes The stability of the cycle can be improved against fluctuations in the heat pump cycle.

 [0007] In addition, for pressure sensors, it is difficult to achieve the target COP with large variations in detection values. Therefore, the target is determined based on the actual temperature difference (Δ 検 出) detected from a temperature sensor with little variation. By correcting the pressure (Pt), it is possible to achieve the target COP. In addition, since the pressure reducing valve can be controlled even when either the pressure sensor or the temperature sensor is abnormal, the reliability of the system for the user can be improved.

 [0008] Further, in the invention according to claim 2, the hot water heater for heating the hot water supply in a vapor compression heat pump cycle that moves the heat on the low temperature side to the high temperature side, the compressor sucking and compressing the refrigerant (1) and a radiator (2) configured to exchange heat between the refrigerant discharged from the compressor (1) and the hot water supply water, and the refrigerant flow and the hot water supply flow are opposed to each other. ) Pressure reducing means (3, 30) for reducing the pressure of the refrigerant flowing out from the refrigerant, and evaporating the refrigerant flowing out from the pressure reducing means (3, 30) to absorb the heat, and at the suction side of the compressor (1) When the refrigerant pressure on the high-pressure side is less than a predetermined pressure, the refrigerant flowing out of the radiator (2) and the hot water supply water flowing into the radiator (2) Heat pump that controls the refrigerant pressure on the high-pressure side so that the actual temperature difference (ΔT) of the target becomes the predetermined target temperature difference (ΔΤ) In the water heater,

Set the target pressure (Pt) on the high pressure side at least when starting the heat pump cycle, The refrigerant pressure on the high-pressure side is controlled so that it becomes the pressure (Pt), and the target discharge temperature (Tt) of the refrigerant discharged from the compressor (1) is set, and the target discharge temperature (Tt) and the actual discharge temperature (T ) Is calculated, and the target pressure (Pt) is corrected so that the temperature difference (Δ と 2) is less than or equal to a predetermined value.

 [0009] According to the invention described in claim 2, by directly controlling the pressure reducing means (3, 30) by a high pressure value detected from a pressure sensor having good response, a heat pump cycle caused by an external factor Cycle stability can be improved with respect to fluctuations.

 [0010] In addition, for pressure sensors, it is difficult to achieve the target COP with large variations in detected values, so the target pressure is determined from the actual discharge temperature (T) detected by a temperature sensor with little variation. It is possible to achieve the target COP by correcting (Pt). In addition, since the pressure reducing valve can be controlled even when either the pressure sensor or the temperature sensor is abnormal, the reliability of the system for the user can be improved.

 [0011] In the invention according to claim 3, the target pressure (Pt) is set, the refrigerant pressure on the high pressure side is controlled so as to be the target pressure (Pt), and the target temperature difference (Δ Τ The temperature difference (ΔΤ1) between the actual temperature difference (ΔΤ) and the target pressure (Pt) is corrected so that the temperature difference (ΔΤ1) is less than the specified value. It is characterized in that it is performed when at least four of the inlet refrigerant temperature of (4) and the outlet refrigerant temperature of the evaporator (4) are lower than a predetermined value.

 [0012] When the operating environment is a low outside air temperature (for example, outside air temperature 0 ° C or less), when trying to control the optimum high pressure FZB pressure reducing valve that forms the optimum COP, the relationship between the heat capacity of the functional parts and heat pump cycle, etc. A temperature sensor such as a thermistor causes a delay in temperature detection, making it difficult to control the decompression means (3, 30) in real time, and it is necessary to ensure stability against fluctuations in the heat pump cycle.

[0013] According to the invention of claim 3, at least one of the outside air temperature, the inlet refrigerant temperature of the evaporator (4), and the outlet refrigerant temperature of the evaporator (4) is more than a predetermined value. At low temperatures (eg, 0 ° C or less) and low temperatures, cycle stability can be improved by performing high-pressure FZB pressure reducing valve control using a pressure sensor. Also, the outside air temperature, the inlet of the evaporator (4) When at least four of the refrigerant temperature and the outlet refrigerant temperature of the evaporator (4) are higher than the specified value or high (for example, over 0 ° C), the high-pressure FZB pressure-reducing valve according to the target COP Boiling operation is performed by control.

 [0014] This makes it possible to secure stable heating capacity that prevents the system from stopping abnormally by using pressure sensor values at low outside air temperatures, and to use temperature sensor values at high outside air temperatures. The high-pressure FZB pressure-reducing valve control that has been used makes it possible to obtain the target COP.

 [0015] In the invention according to claim 4, the target pressure (Pt) is set, the refrigerant pressure on the high-pressure side is controlled so as to be the target pressure (Pt), and the compressor (1) Set the target discharge temperature (Tt) of the refrigerant to be discharged, calculate the temperature difference (ΔΤ2) between the target discharge temperature (Tt) and the actual discharge temperature (T), and the temperature difference (ΔΤ2) is less than the predetermined value The control to correct the target pressure (Pt) is performed when at least one of the outside air temperature, the inlet refrigerant temperature of the evaporator (4), and the outlet refrigerant temperature of the evaporator (4) is lower than a predetermined value. It is characterized by that.

 [0016] When the operating environment is a low outside air temperature (for example, outside air temperature 0 ° C or less), the temperature sensor such as a thermistor has a temperature detection delay due to the heat capacity of the functional parts and heat pump cycle, and the pressure reducing means (3, It may be difficult to control 30) in real time, and it is necessary to ensure stability against fluctuations in the heat pump cycle.

 [0017] According to the invention of claim 4, at least one of the outside air temperature, the inlet refrigerant temperature of the evaporator (4), and the outlet refrigerant temperature of the evaporator (4) is more than a predetermined value. At low temperatures (eg, 0 ° C or less) and low temperatures, cycle stability can be improved by performing high-pressure FZB pressure reducing valve control using a pressure sensor. In addition, at least four of the outside air temperature, the refrigerant temperature at the inlet of the evaporator (4), and the refrigerant temperature at the outlet of the evaporator (4) are higher than a predetermined value or high (for example, exceeding 0 ° C). The boiling operation is performed by controlling the high pressure FZB pressure reducing valve according to the target COP.

[0018] This makes it possible to emphasize the stability of the cycle by using the pressure sensor value at low outside air temperature, and to ensure stable heating capacity that prevents the system from abnormally stopping, and use the temperature sensor value at high outside air temperature. The high-pressure FZB pressure-reducing valve control that has been used makes it possible to obtain the target COP. [0019] In the invention according to claim 5, it is provided between the downstream side of the refrigerant flow of the radiator (2) and the pressure reducing means (3, 30), or upstream of the refrigerant flow of the radiator (2). And a pressure sensor (10) for detecting the high-pressure side pressure of the refrigerant. According to the invention described in claim 5, by using a pressure sensor (10) having a high responsiveness as a means for detecting a high pressure, the cycle of the heat pump can be prevented from changing due to an external factor. Stability can be improved.

 [0020] Further, in the invention according to claim 6, the compressor (1) for sucking and compressing the refrigerant, and the compressor (1) force exchange heat between the refrigerant discharged and the hot water supply water, and the refrigerant flow and the hot water supply water. A radiator (2) configured to face the flow, a decompression means (3, 30) for decompressing the refrigerant flowing out of the radiator (2), and a refrigerant flowing out of the decompression means (3, 30) And an evaporator (4) that flows out the refrigerant toward the suction side of the compressor (1), and flows out of the radiator (2) when the refrigerant pressure on the high-pressure side is lower than a predetermined pressure. In a heat pump water heater that controls the refrigerant pressure on the high-pressure side so that the actual temperature difference (ΔΤ) between the refrigerant that flows into the radiator (2) and the hot-water supply water flowing into the radiator (2) becomes the predetermined target temperature difference (ATt).

 It has a discharge temperature sensor (8) that detects the discharge temperature of the refrigerant discharged from the compressor (1), and at least when the heat pump cycle starts, the target discharge temperature (Tt) of the refrigerant discharged from the compressor (1) Set and calculate the temperature difference (Δ Τ2) between the target discharge temperature (Tt) and the actual discharge temperature (T), and correct the target discharge temperature (Tt) so that the temperature difference (Δ Τ2) is less than the specified value. It is characterized by this.

 [0021] According to the invention described in claim 6, it is possible to detect the state of the refrigerant on the high-pressure side using the temperature sensor (8) having a smaller detection value variation than the pressure sensor (10). It will be possible to achieve the target COP more reliably.

 [0022] In the invention according to claim 7, the target discharge temperature (Tt) is corrected so that the temperature difference (ΔT2) between the target discharge temperature (Tt) and the actual discharge temperature (T) is equal to or less than a predetermined value. This control is performed when at least four of the outside air temperature, the inlet refrigerant temperature of the evaporator (4), and the outlet refrigerant temperature of the evaporator (4) are lower than a predetermined value.

[0023] According to the invention of claim 7, importance is placed on the stability of the vacancies using the pressure sensor value at a low outside air temperature so that the system does not stop abnormally and a stable heating capacity is ensured. OK At high outside air temperatures, high pressure FZB pressure reducing valve control using temperature sensor values enables operation to obtain the target COP. Incidentally, the reference numerals in parentheses of the above means are examples showing the correspondence with the specific means described in the embodiments described later.

 Brief Description of Drawings

 FIG. 1 is a schematic diagram showing a configuration of a heat pump type water heater in a first embodiment of the present invention.

 2 is a flowchart showing a control example of the control device 16 in the embodiment of FIG.

 FIG. 3 is a graph showing an example of control characteristics of high-pressure F / B pressure reducing valve control in the flowchart of FIG.

 4 is a graph showing an example of correction characteristics of high-pressure correction in the flowchart of FIG.

 FIG. 5 is a flowchart showing a control example of the control device 16 in the second embodiment of the present invention.

 FIG. 6 is an example of a map for calculating a target discharge temperature Tt in the flowchart of FIG.

7 is a graph showing an example of correction characteristics of high pressure correction in the flowchart of FIG.

 FIG. 8 is a flowchart showing a control example of the control device 16 in the third embodiment of the present invention.

 FIG. 9 is a graph showing an example of control characteristics of temperature difference FZB pressure reducing valve control in the flowchart of FIG. 8.

 FIG. 10 is a flowchart showing a control example of the control device 16 in the fourth embodiment of the present invention.

 FIG. 11 is a graph showing an example of control characteristics of discharge temperature difference F / B pressure reducing valve control in the flowchart of FIG. 10.

 FIG. 12 is a schematic diagram showing a configuration of a heat pump type water heater in another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0025] (First embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the heat pump type water heater in the first embodiment of the present invention. The heat pump type water heater in this embodiment has a hot water storage tank 6 for storing hot water supply water, a flowing water pipe C′H connected to the hot water storage tank 6, and a water supply water flowing through the flowing water pipe C′H. It consists of a data pump 7, a heat pump unit HU of a supercritical heat pump cycle, which will be described later, which is a means for heating hot water, and a control device 16 that controls the operation of the heat pump water heater.

 [0026] The hot water storage tank 6 is made of metal (for example, made of stainless steel) excellent in corrosion resistance and has a heat insulating structure, and can keep hot hot water for a long time. Hot water stored in the hot water storage tank 6 is mixed with cold water and adjusted in temperature during use, and is mainly used in kitchens and baths.In addition to hot water, for example, for floor heating or indoor air conditioning It can also be used as a heat source.

 The flowing water pipe C 1 H is composed of a cold water pipe C and a hot water pipe H that connect the hot water storage tank 6 and a hydrothermal exchanger (radiator) 2 described later. One end of the chilled water pipe C is connected to a chilled water outlet 6 a provided in the lower part of the hot water storage tank 6, and the other end is connected to an inlet of a water passage (not shown) provided in the hydrothermal exchanger 2. The hot water pipe H has one end connected to an outlet of a water passage (not shown) provided in the water heat exchanger 2 and the other end connected to a hot water inlet 6b provided in the upper part of the hot water storage tank 6.

 [0028] In the water pump 7, as shown by the arrow in FIG. 1, the hot water in the hot water storage tank 6 flows from the cold water outlet 6a to the cold water pipe C → water passage → hot water pipe H and from the hot water inlet 6b to the hot water tank 6 A water flow is generated so as to recirculate. The water pump 7 can adjust the amount of flowing water according to the rotation speed of a motor (not shown) incorporated therein, and is energized and controlled by the control device 16.

 [0029] As shown in Fig. 1, the supercritical heat pump cycle includes a compressor 1, a water heat exchanger 2, a variable expansion valve 3 as a decompression means, an air heat exchanger (evaporator) 4, an accumulator 5, It consists of refrigerant pipes (high-pressure pipe Hi and low-pressure pipe Lo) that connect these devices, and carbon dioxide (hereinafter abbreviated as C02) refrigerant with a low critical temperature is enclosed as the refrigerant.

[0030] The compressor 1 is driven by a built-in motor (not shown) and receives the sucked gas refrigerant. Compress to discharge above the field pressure and discharge. The refrigerant discharge amount of the compressor 1 varies according to the rotation speed of the motor.

 [0031] The water heat exchanger 2 exchanges heat between the high-temperature and high-pressure gas refrigerant pressurized by the compressor 1 and the hot water supplied from the hot water storage tank 6, and is adjacent to the water passage described above. A refrigerant passage (not shown) is provided, and the flow direction of the refrigerant flowing through the refrigerant passage is opposed to the flow direction of hot water supply water flowing through the water passage.

 [0032] The variable expansion valve 3 is provided between the water heat exchanger 2 and the air heat exchanger 4, and the water heat exchanger

 The refrigerant cooled in 2 is decompressed and supplied to the air heat exchanger 4. The variable expansion valve 3 has a configuration in which the valve opening degree can be electrically adjusted, and is energized and controlled by the control device 16.

 [0033] The air heat exchanger 4 receives air blown by the outside air fan 4a, and evaporates the refrigerant decompressed by the variable expansion valve 3 by heat exchange with the outside air. The accumulator 5 gas-liquid separates the refrigerant evaporated in the air heat exchanger 4 and stores surplus refrigerant in the cycle, and causes the compressor 1 to suck only the gas refrigerant.

 [0034] Next, sensors arranged in each part of the above-described heat pump type water heater will be described. 8 is a discharge temperature sensor that detects the discharge temperature of the refrigerant discharged from the compressor 1, and 9 is an outlet refrigerant temperature sensor that detects the temperature of the refrigerant flowing out of the water heat exchanger 2. Reference numeral 10 denotes a pressure sensor which is set on the inlet side or the outlet side of the water heat exchanger 2 and detects the high pressure on the high pressure pipe Hi side.

 [0035] 11 is a refrigerant temperature sensor at the inlet of the air heat exchanger 4, and 12 is a refrigerant temperature sensor at the outlet of the air heat exchanger 4. Reference numeral 13 denotes an outside air temperature sensor that detects the ambient air temperature. Reference numeral 14 denotes a water temperature sensor that detects the temperature of the inlet water flowing into the water heat exchanger 2, and reference numeral 15 denotes a boiling temperature sensor that detects the hot water temperature of the hot water supply water. All signals detected by these sensor groups are input to the control device 16, and the energization control of the compressor 1, the variable expansion valve 3, the outside air fan 4a, the water pump 7, and the like is controlled according to a flowchart and the like described later.

Next, the normal boiling operation will be described. The refrigerant is pressurized by the compressor 1 to become high temperature and pressure, dissipates heat to the hot water supply water in the water heat exchanger 2 and is cooled, supplied to the variable expansion valve 3, and according to the opening of the variable expansion valve 3. Depressurized. Depressurized low-temperature low-pressure refrigerant The air heat exchanger 4 (outside air fan 4a: operating) absorbs heat from outside air and evaporates, and after the gas and liquid are separated by the accumulator 5, the cycle in which only the gas refrigerant is sucked into the compressor 1 is repeated.

The hot water supply water is pressurized by the water pump 7, absorbs heat from the refrigerant in the water heat exchanger 2 to become hot water, and is sent to the hot water storage tank 6 for storage. The boiling temperature is controlled by detecting the hot water temperature with the boiling temperature sensor 15 and adjusting the circulation flow rate with the water pump 7. When the water temperature sensor 14 detects that the hot water storage tank 6 has become hot water and the temperature of the water supply from the cold water pipe C has increased, the circulation of the refrigerant and hot water is stopped.

 [0038] Next, the operation of the heat pump type water heater 1 during the boiling operation according to the present invention will be described. FIG. 2 is a flowchart showing an example of control of the control device 16 in the embodiment of FIG. FIG. 3 is a graph showing an example of control characteristics of high-pressure F / B pressure reducing valve control in the flowchart of FIG. 2, and is a graph showing an example of correction characteristics of high-pressure correction in the flowchart of FIG.

 [0039] In general, the heat pump type hot water heater 1 of the present invention first temporarily sets a target high pressure Pt when the heat pump is started, and detects the high pressure with the pressure sensor 10, while the variable expansion valve 3 detects the target high pressure Pt. In addition, the actual temperature difference ΔΤ between the inlet water temperature and the outlet refrigerant temperature of the water heat exchanger 2 is detected and set, and the target COP (this implementation) is set. In the form, it is a system that corrects the COP to the highest value).

 [0040] When the heating operation in the heat pump system is started by the operation command from the control device 16, first, in step S1 of Fig. 2, it is determined from the outside air temperature 'water temperature at the inlet of the water heat exchanger 2' target boiling temperature, etc. Estimate the high pressure when the cycle is stabilized and tentatively set the target high pressure Pt.

[0041] In the next step S2, each cycle function product such as compressor 1, outdoor fan 4a, water pump 7, etc. is operated, and the pressure sensor 10 detects the actual pressure to reach the target high pressure Pt. Control the opening of expansion valve 3 (high pressure FZB pressure reducing valve control). FIG. 3 shows an example of control characteristics of the variable expansion valve 3. If the actual high pressure is lower than the target high pressure, the expansion valve is throttled. If the actual high pressure is higher than the target high pressure, the expansion valve is opened. And real height As the pressure approaches the target high pressure, the opening of the expansion valve is reduced to improve the stability of the heat pump cycle.

 [0042] In the next step S3, it is determined whether or not the target high pressure has been reached. If the determination result is NO, the target high pressure has been reached. B Continue pressure reducing valve control. If the target high pressure is reached and the determination result in step S3 is YES, the process proceeds to step S4, and the actual temperature difference ΔΤ between the inlet water temperature and the outlet refrigerant temperature of the water heat exchanger 2 is detected. In step S5, the target temperature difference A Tt to achieve the optimum COP and the temperature difference ΔΤ1 between the actual temperature difference ΔΤ are calculated. The target temperature difference may be a predetermined value (for example, 10 ° C.) or may be calculated according to a map.

 [0043] In the next step S6, it is determined whether or not the absolute value of the temperature difference ΔΤ1 calculated in step S5 is equal to or less than a predetermined value (3 ° C in this example). If the determination result is NO and the absolute value of the temperature difference ΔΤ1 is greater than or equal to the predetermined value, the process proceeds to step S7, the target high pressure Pt is corrected, and the high pressure F / B pressure reducing valve control in step S2 is repeated. is there. Figure 4 shows an example of correction characteristics for high-pressure correction. If the temperature difference ΔΤ1 calculated in step S5 is positive (if the actual temperature difference ΔΤ is insufficient for the target temperature difference ΔTt), the target high pressure Pt is positively corrected, and if it is negative (the actual temperature difference ΔT is the target) When the temperature difference ΔTt is exceeded), the target high pressure Pt is negatively corrected.

 [0044] If the absolute value of the temperature difference ΔΤ1 is equal to or smaller than the predetermined value and the determination result in step S6 is YES, the process proceeds to step S8, and the target high pressure is not corrected, and thereafter the optimum high pressure F ZB Shift to pressure reducing valve control. In step S9, it is determined whether or not an operation stop command has been input.If the determination result is NO and no operation stop command is input, the optimum high pressure FZB pressure reducing valve control in step S8 is continued. When the operation stop command is input and the judgment result in step S9 is YES, the above boiling operation is terminated.

Next, features and effects of this embodiment will be described. At least when starting the heat pump site, set the target pressure Pt on the high pressure side and control the refrigerant pressure on the high pressure side so that it reaches the target pressure Pt. Also, the temperature difference ΔΤ1 between the target temperature difference A Tt and the actual temperature difference ΔΤ The target pressure Pt is corrected so that the temperature difference Δ Τ1 is less than the predetermined value. [0046] According to this, by directly controlling the variable expansion valve 3 with a high pressure value detected by a pressure sensor with good response, the cycle is stabilized against changes in the heat pump cycle due to external factors. Can be improved.

 [0047] For the pressure sensor, the variation in the detected value is large, and it is difficult to achieve the target COP. Therefore, the target pressure Pt is calculated from the actual temperature difference ΔΤ detected by a temperature sensor with little variation. By correcting it, it is possible to achieve the target COP. In addition, if either the pressure sensor or the temperature sensor is abnormal, the pressure reducing valve can be controlled even if it is abnormal, so that the reliability of the system on the user side can be improved.

 [0048] (Second Embodiment)

 FIG. 5 is a flowchart showing a control example of the control device 16 in the second embodiment of the present invention. FIG. 6 is an example of a map for calculating the target discharge temperature Tt in the flowchart of FIG. 5, and FIG. 7 is a graph showing an example of correction characteristics of high pressure correction in the flowchart of FIG. The configuration of the heat pump type hot water heater is the same as that of the first embodiment described above. As in the first embodiment, the target pressure Pt is corrected by the temperature difference while performing the high pressure F / B pressure reducing valve control. The difference is that the temperature difference is calculated using the discharge temperature of the refrigerant discharged from machine 1.

 [0049] When the heating operation in the heat pump system is started by the operation command from the control device 16, first, in step S11 of Fig. 5, it is determined from the outside air temperature 'the inlet water temperature of the water heat exchanger 2' the target boiling temperature, etc. Estimate the high pressure when the cycle is stabilized and tentatively set the target high pressure Pt.

[0050] In the next step S12, each cycle function product such as compressor 1, outside air fan 4a, water pump 7, etc. is operated and variable while detecting the actual pressure with pressure sensor 10 so as to reach the target high pressure Pt. Controls the opening of the expansion valve 3 (high pressure FZB pressure reducing valve control). FIG. 3 shows an example of control characteristics of the variable expansion valve 3. If the actual high pressure is lower than the target high pressure, the expansion valve is throttled. If the actual high pressure is higher than the target high pressure, the expansion valve is opened. As the actual high pressure approaches the target high pressure, the opening degree of the expansion valve is decreased to improve the stability of the heat pump cycle. [0051] In the next step S13, it is determined whether or not the target high pressure has been reached. If the determination result is N0, the target high pressure has been reached. / B Continues pressure reducing valve control. If the target high pressure is reached and the judgment result in step S13 is YES, the process proceeds to step S14, and the target discharge temperature Tt is calculated from the outside air temperature and the target boiling temperature according to the map in Fig. 6 or the calculation formula). Is calculated. In step S15, a temperature difference ΔΤ2 between the target discharge temperature Tt and the actual discharge temperature T for achieving the optimum COP is calculated.

 In the next step S16, it is determined whether or not the absolute value of the temperature difference ΔΤ2 calculated in step S15 is equal to or less than a predetermined value (3 ° C. in this example). If the determination result is NO and the absolute value of the temperature difference ΔΤ2 is greater than or equal to the predetermined value, the process proceeds to step S17 to correct the target high pressure Pt and repeat from the high pressure F / B pressure reducing valve control in step S12 again. is there. Figure 7 shows an example of correction characteristics for high-pressure correction. If the temperature difference ΔT2 calculated in step S15 is positive (if the actual discharge temperature is less than the target discharge temperature Tt), the target high pressure Pt is positively corrected; if it is negative (the actual discharge temperature is the target discharge temperature Tt) ), The target high pressure Pt is negatively corrected.

 [0053] If the absolute value of the temperature difference ΔΤ2 is equal to or smaller than the predetermined value and the determination result in step S16 is YES, the process proceeds to step S18, and the target high pressure is not corrected. Shifts to / B pressure reducing valve control. In step S19, it is determined whether or not an operation stop command has been input.If the determination result is NO and no operation stop command is input, the optimum high pressure F / B pressure reducing valve control in step S18 is performed. When the operation stop command is input and the judgment result in step S19 is YES, the above boiling operation is terminated.

 Next, features and effects of this embodiment will be described. At least when starting the heat pump site, set the target pressure Pt on the high pressure side, control the refrigerant pressure on the high pressure side so that it becomes the target pressure Pt, and set the target discharge temperature Tt of the refrigerant discharged from the compressor 1. The temperature difference ΔΤ2 between the target discharge temperature Tt and the actual discharge temperature T is calculated, and the target pressure Pt is corrected so that the temperature difference ΔΤ2 is not more than a predetermined value.

[0055] According to this, by directly controlling the variable expansion valve 3 with a high pressure value detected by a pressure sensor having good response, the heat pump cycle can be changed by an external factor. The stability of the cycle with respect to the movement can be improved.

 [0056] For the pressure sensor, the variation in the detected value is large. It is difficult to achieve the target COP. Therefore, the target pressure Pt is corrected from the actual discharge temperature T detected by a temperature sensor with little variation. By doing so, it is possible to achieve the target COP. In addition, if either the pressure sensor or the temperature sensor is abnormal, the pressure reducing valve can be controlled even if it is abnormal, so that the reliability of the system on the user side can be improved.

 [0057] (Third embodiment)

 FIG. 8 is a flowchart showing a control example of the control device 16 in the third embodiment of the present invention. The present invention controls the high-pressure F / B pressure reducing valve according to the outside air temperature detected by the outside air temperature sensor 13. It becomes a system that switches between the temperature difference and F / B pressure reducing valve control. In step S21, it is determined whether or not the outside air temperature is equal to or higher than a predetermined value (0 ° C. in this embodiment). If the result is YES and the outside air temperature is 0 ° C or higher, go to step 22 and set the target temperature difference to achieve the optimum COP.

 [0058] In step S23, the actual temperature difference between the inlet water temperature of the water heat exchanger 2 and the outlet refrigerant temperature.

 ΔΤ is detected and temperature difference F / B pressure reducing valve control is performed to control the variable expansion valve 3 so that the target temperature difference ATt is obtained. FIG. 9 is a graph showing an example of control characteristics of the temperature difference F / B pressure reducing valve control in the flowchart of FIG. 8. When the temperature difference ΔΤ1 is positive (the actual temperature difference ΔΤ is insufficient for the target temperature difference ATt). ), The expansion valve is throttled, and when it is negative (when the actual temperature difference ΔΤ exceeds the target temperature difference A Tt), the expansion valve is opened. Note that the target temperature difference Δ で あ t may be a predetermined value (for example, 10 ° C.) or may be calculated according to a map.

[0059] If the determination result in step S21 is NO and the outside air temperature is lower than 0 ° C, the routine proceeds to step 24, where the target high pressure Pt is set temporarily, and thereafter step S25 is set. The pressure sensor 10 detects the high pressure while controlling the variable expansion valve 3 so that it reaches the target high pressure Pt, and the actual temperature difference between the inlet water temperature and the outlet refrigerant temperature of the water heat exchanger 2 Δ T Is detected, and the target high pressure Pt that has been set is corrected to the optimum value for the highest COP, and high pressure FZB pressure reducing valve control is performed. Next, features and effects of this embodiment will be described. The target pressure Pt is set and the refrigerant pressure on the high-pressure side is controlled so as to be the target pressure Pt, and the temperature difference ΔΤ1 between the target temperature difference ΔTt and the actual temperature difference ΔΤ is calculated, and the temperature difference Control that corrects the target pressure Pt so that ΔΤ1 is less than or equal to a predetermined value is at least four of the outside air temperature, the inlet refrigerant temperature of the evaporator 4 and the outlet refrigerant temperature of the air heat exchanger 4 are lower than the predetermined value. If you are going to do it.

 [0061] When the operating environment is a low outside air temperature (for example, outside air temperature 0 ° C or less), if the optimum high pressure F / B pressure reducing valve control that constitutes the optimum COP is performed, the heat capacity of functional parts, heat pump cycles, etc. For this reason, a temperature sensor such as a thermistor causes a temperature detection delay, making it difficult to control the variable expansion valve 3 in real time, and it is necessary to ensure stability against fluctuations in the heat pump cycle.

 [0062] According to this, at least one of the outside air temperature, the inlet refrigerant temperature of the air heat exchanger 4 and the outlet refrigerant temperature of the air heat exchanger 4 is lower than a predetermined value (for example, 0 ° C or less) ) At low temperatures, cycle stability can be improved by controlling the high pressure F / B pressure reducing valve using a pressure sensor. In addition, at least one of the outside air temperature, the inlet refrigerant temperature of the air heat exchanger 4 and the outlet refrigerant temperature of the air heat exchanger 4 is higher than a predetermined value or high (for example, exceeding 0 ° C). The boiling operation is performed by controlling the high-pressure F / B pressure reducing valve according to the target COP.

 [0063] This makes it possible to secure stable heating capacity that prevents abnormal system shutdown by using pressure sensor values at low outside air temperatures, and to use temperature sensor values at high outside air temperatures. The high-pressure FZB pressure-reducing valve control that has been used makes it possible to obtain the target COP.

 [0064] (Fourth embodiment)

FIG. 10 is a flowchart showing a control example of the control device 16 according to the fourth embodiment of the present invention. The present invention is a high pressure FZB pressure reducing valve according to the outside air temperature detected by the outside air temperature sensor 13. This system switches between control and discharge temperature difference F / B pressure reducing valve control. In step S31, it is determined whether or not the outside air temperature is equal to or higher than a predetermined value (0 ° C. in this embodiment). If the result is YES and the outside air temperature is 0 ° C or higher, step 32 Go to, and set the target discharge temperature Tt to achieve the optimal COP.

 [0065] In step S33, the actual discharge temperature T of the compressor 1 is detected, and the discharge temperature difference FZB pressure reducing valve control for controlling the variable expansion valve 3 so as to reach the target discharge temperature Tt is performed. Fig. 11 is a graph showing an example of the control characteristics of the discharge temperature difference F / B pressure reducing valve control in the flowchart of Fig. 10. When the temperature difference ΔΤ2 is positive (when the actual discharge temperature T is lower than the target discharge temperature T) The throttle valve throttles the expansion valve, and when it is negative (when the actual discharge temperature T is higher than the target discharge temperature T), the expansion valve opens.

 [0066] If the determination result in step S31 is NO and the outside air temperature is lower than 0 ° C, the routine proceeds to step 34, where the target high pressure Pt is set temporarily, and thereafter, the process proceeds to step S35. The pressure sensor 10 detects the high pressure and controls the variable expansion valve 3 so that the target high pressure Pt is reached.In addition, the actual temperature difference Δ T between the inlet water temperature and the outlet refrigerant temperature of the water heat exchanger 2 is calculated. This detects and sets the target high pressure Pt, which is corrected to the optimum value for the highest COP, and performs high pressure F / B pressure reducing valve control.

 Next, features and effects of this embodiment will be described. The target pressure Pt is set, the refrigerant pressure on the high-pressure side is controlled so that the target pressure Pt is reached, the target discharge temperature Tt of the refrigerant discharged from the compressor 1 is set, and the target discharge temperature Tt and the actual discharge are set. The control to correct the target pressure Pt so that the temperature difference Δ Τ2 with respect to the temperature T is calculated and the temperature difference Δ 以下 2 is below the specified value is controlled by the outside air temperature, the inlet refrigerant temperature of the air heat exchanger 4, and the air heat. This is performed when at least one of the outlet refrigerant temperatures of the exchanger 4 is lower than a predetermined value.

 [0068] When the operating environment is a low outside air temperature (for example, outside air temperature 0 ° C or less), the temperature sensor such as a thermistor has a temperature detection delay due to the heat capacity of the functional parts and heat pump cycle. It may be difficult to control the heat in real time, and it is necessary to ensure stability against fluctuations in the heat pump cycle.

 [0069] According to the above-described embodiment, the stability of the cycle can be emphasized by using the pressure sensor value at the time of the low outside air temperature, and it is possible to ensure a stable heating capacity that prevents the system from abnormally stopping, and at the time of the high outside air temperature. High pressure F / B pressure reducing valve control using temperature sensor value enables operation that can achieve the target COP.

[0070] (Other Embodiments) FIG. 12 is a schematic diagram showing a configuration of a heat pump type water heater in another embodiment of the present invention. In the above-described embodiment, the pressure reducing means is the variable expansion valve 3, but the present invention is not limited to the above-described embodiment, and as shown in FIG. 12, a heat pump cycle using an ejector 30 as the pressure reducing means. Even so, it exhibits the same effect.

 In the above-described embodiment, the embodiment has been described in which the high-pressure side target pressure Pt is set when the heat pump cycle is started, but the target discharge temperature Tt of the refrigerant discharged from the compressor 1 instead of the high-pressure side target pressure Pt. The same effect can be obtained by performing control for correcting the target temperature difference Tt so that the temperature difference ΔΤ2 between the target discharge temperature Tt and the actual discharge temperature is equal to or less than a predetermined value.

Claims

The scope of the claims  [1] A water heater that heats hot water in a vapor compression heat pump cycle that moves heat on a low temperature side to a high temperature side,  A compressor (1) for sucking and compressing refrigerant;  A heat exchanger (2) configured to exchange heat between the refrigerant discharged from the compressor (1) and the hot water supply water, and to oppose the refrigerant flow and the hot water supply water flow;  Decompression means (3, 30) for decompressing the refrigerant flowing out of the radiator (2);  There is an evaporator (4) that evaporates the refrigerant flowing out from the decompression means (3, 30) and absorbs heat into the refrigerant, and also flows out the refrigerant toward the suction side of the compressor (1). When the refrigerant pressure on the high pressure side is less than the predetermined pressure, the actual temperature difference (ΔΤ) between the refrigerant flowing out of the radiator (2) and the hot water supplying water flowing into the radiator (2) is a predetermined target temperature. In the heat pump water heater that controls the refrigerant pressure on the high pressure side so that the difference (A Tt) is obtained, the target pressure (Pt) on the high pressure side is set at least at the start of the heat pump cycle so that it becomes the target pressure (Pt) In addition to controlling the refrigerant pressure on the high pressure side, the temperature difference (ΔT1) between the target temperature difference (ΔTt) and the actual temperature difference (ΔT) is calculated, and the temperature difference (ΔT1) is a predetermined value. A heat pump hot water supply, wherein the target pressure (Pt) is corrected so as to satisfy the following conditions.  [2] A water heater that heats hot water in a vapor compression heat pump cycle that moves heat on a low temperature side to a high temperature side,  A compressor (1) for sucking and compressing refrigerant;  A heat exchanger (2) configured to exchange heat between the refrigerant discharged from the compressor (1) and the hot water supply water, and to oppose the refrigerant flow and the hot water supply water flow;  Decompression means (3, 30) for decompressing the refrigerant flowing out of the radiator (2); There is an evaporator (4) that evaporates the refrigerant flowing out from the decompression means (3, 30) and absorbs heat into the refrigerant, and also flows out the refrigerant toward the suction side of the compressor (1). When the refrigerant pressure on the high pressure side is less than the predetermined pressure, the actual temperature difference (ΔΤ) between the refrigerant flowing out of the radiator (2) and the hot water supplying water flowing into the radiator (2) is a predetermined target temperature. In the heat pump water heater that controls the refrigerant pressure on the high pressure side so as to be the difference (A Tt), At least at the start of the heat pump cycle, the target pressure (Pt) on the high pressure side is set, the refrigerant pressure on the high pressure side is controlled so as to be the target pressure (Pt), and the refrigerant discharged from the compressor (1) is controlled. Set the target discharge temperature (Tt), calculate the temperature difference (ΔΤ2) between the target discharge temperature (Tt) and the actual discharge temperature (T), and make the temperature difference (ΔΤ2) less than the predetermined value A heat pump type water heater characterized by correcting the target pressure (Pt).  [3] The target pressure (Pt) is set, and the refrigerant pressure on the high pressure side is controlled so as to be the target pressure (Pt), and the target temperature difference (Δ Δ and the actual temperature difference (Δ Δ) And the control for correcting the target pressure (Pt) so that the temperature difference (Δ Τ1) is less than or equal to a predetermined value is calculated using the outside air temperature and the inlet of the evaporator (4) 2. The heat pump type water heater according to claim 1, wherein the heat pump type hot water heater is performed when at least one of the refrigerant temperature and the outlet refrigerant temperature of the evaporator (4) is lower than a predetermined value.  [4] The target pressure (Pt) is set, the refrigerant pressure on the high-pressure side is controlled so as to be the target pressure (Pt), and the target discharge temperature of the refrigerant discharged from the compressor (1) ( Tt) is calculated, and a temperature difference (ΔΤ2) between the target discharge temperature (Tt) and the actual discharge temperature (T) is calculated, and the target pressure (ΔΤ2) is reduced to a predetermined value or less. Pt) is controlled when at least one of the outside air temperature, the inlet refrigerant temperature of the evaporator (4), and the outlet refrigerant temperature of the evaporator (4) is lower than a predetermined value. A heat pump type water heater according to claim 2.  [5] Provided between the refrigerant flow downstream side of the radiator (2) and the decompression means (3, 30) or upstream of the refrigerant flow of the heat radiator (2), The heat pump type water heater according to any one of claims 1 to 4, further comprising a pressure sensor (10) for detection. [6] a compressor (1) for sucking and compressing refrigerant;  A heat exchanger (2) configured to exchange heat between the refrigerant discharged from the compressor (1) and the hot water supply water, and to oppose the refrigerant flow and the hot water supply water flow;  Decompression means (3, 30) for decompressing the refrigerant flowing out of the radiator (2); An evaporator (4) for evaporating the refrigerant flowing out of the decompression means (3, 30) and for flowing out the refrigerant toward the suction side of the compressor (1); When the refrigerant pressure on the high pressure side is less than a predetermined pressure, the actual temperature difference (ΔT) between the refrigerant flowing out of the radiator (2) and the hot water supply water flowing into the radiator (2) is a predetermined target temperature difference ( In the heat pump water heater that controls the refrigerant pressure on the high pressure side so that ΔTt), the discharge temperature sensor (8) that detects the discharge temperature of the refrigerant discharged from the compressor (1),  Set the target discharge temperature (Tt) of the refrigerant discharged from the compressor (1) at least at the start of the heat pump cycle, and the temperature difference between the target discharge temperature (Tt) and the actual discharge temperature (T) (Δ Τ 2) And the target discharge temperature (Tt) is corrected so that the temperature difference (ΔΤ2) is equal to or less than a predetermined value.  Control for correcting the target discharge temperature (Tt) so that the temperature difference (ΔΤ2) between the target discharge temperature (Tt) and the actual discharge temperature (T) is equal to or less than a predetermined value is the outside air temperature, the evaporator ( 7. The heat pump hot water supply according to claim 6, which is performed when at least one of an inlet refrigerant temperature of 4) and an outlet refrigerant temperature of the evaporator (4) is lower than a predetermined value.