JP5582053B2 - Heat pump hot water heater - Google Patents

Description

  The present invention relates to energy saving control of a heat pump hot water heater.

  The conventional heat pump hot water heater includes a heat pump cycle and a water heating medium cycle, and the refrigerant flowing through the heat pump cycle heats the water heating medium flowing through the water heating medium cycle by the water heating medium heat exchanger 115, and the heated water. The heat medium is sent to the plurality of indoor radiators 125 to dissipate heat and heat the room. A circulating pump 121 driven by an alternating current or direct current power source is used as a means for feeding the water heating medium.

  When an AC power supply circulation pump is used, since it always operates with a constant head, as long as the number of indoor radiators that perform heating operation is the same, the circulation flow rate of the hydrothermal medium is always the same. AC power supply driven circulation pumps are widely used because of their low cost and easy control.

  However, since the circulation amount of the hydrothermal medium is constant, the efficiency of the heat pump hot water heater may deteriorate.

  The explanation will be made with a heat pump hot water heater in which the total number of indoor radiators is four and the circulation pump 121 driven by an AC power source supplies 6.0 L of a water heating medium per minute.

  As an example in which the efficiency of the heat pump hot water heater deteriorates, the water heat medium is sent to all four indoor radiators (125a to 125d), and the forward temperature Two of the water heat medium flowing out from the water heat medium heat exchanger 115 is From a state in which the heat amount that heats the water heat medium by the water heat medium heat exchanger 115 and the heat amount that dissipates the heat from the indoor radiator 125 is equal to the target going temperature Twot, 3 according to the user setting. The state after stopping water supply of the hydrothermal medium to indoor heat dissipation (125a-125c) of a stand is mentioned.

  Assuming that all of the indoor radiators 125a to 125d are the same, the flow rate of the water heating medium sent to each indoor radiator in a state where the water heating medium is fed to all four indoor radiators. Is 6.0 L / 4 = 1.5 L per minute.

  Here, when the water supply of the water heat medium to the indoor radiators 125a to 125c is stopped, the circulation amount of the water heat medium in the remaining indoor radiator 125d is greatly increased to 6.0 L per minute, which is four times as much.

  Actually, as the amount of the water heat medium flowing through the water heat medium pipe laid in the indoor radiator increases, the resistance increases. Therefore, the circulation amount of the water heat medium in the indoor radiator 125d is 6. Although the value is a little smaller than 0L, here it is assumed to be 6.0L per minute for simplification.

Generally, the return temperature Two of the water heat medium flowing out from the water heat medium heat exchanger 115, the return temperature Twi flowing into the water heat medium heat exchanger 115, and the circulation of the water heat medium flowing through the water heat medium heat exchanger 115 The relational expression shown in Equation 1 holds between the quantity M _E and the quantity of heat Q _E for heating the water heat medium in the water heat medium heat exchanger 115.

(Equation 1) Q _E = (Two−Twi) × M _E
Further, the temperature of the hydrothermal medium flowing out from the indoor radiator 125i (i = a to d) is Twi _i , the circulation amount of the hydrothermal medium flowing through the indoor radiator 125i is M _i , and the indoor radiator 125i radiates heat indoors. Assuming that the amount of heat is Qi and the temperature of the hydrothermal medium flowing into the indoor radiator 125i is equal to the forward temperature Two, the relational expression shown in Equation 2 is established.

(Expression 2) Q _i = (Two−Twi _i ) × M _i
Between Equation 1 and Equation 2, Q _E = ΣQ _i and M _E = ΣM _i hold.

In the above example, the heat radiation amount _{Q d} in the indoor radiator 125d is assumed to be constant, the circulating amount _{M d} hydrothermal medium in the indoor radiator 125d is increased four-fold 6.0L per minute 1.5L Then, from the number 2 of the relationship, the temperature difference two-Twi _d will be reduced to 1/4. However, in practice, since the indoor radiator laid water heating medium inside the pipe within 125d holds a hydrothermal medium number L, the temperature difference Two-Twi _d instantly not reduced to 1/4 .

The reason for this is that even if the circulation amount M _d of the hydrothermal medium increases, the hydrothermal medium that is located closer to the outflow pipe in the indoor radiator 125 _{d at} that moment increases the circulation amount M _d of the hydrothermal medium. This is because the flow out from the indoor radiator 125d without being affected by reducing the temperature drop of the heat transfer medium flowing in the pipe due to the increase. That is, the temperature Twi _d hydrothermal medium flowing out of the indoor radiator 125d gradually rises.

Next, the forward temperature Two of the hydrothermal medium after being heated by the hydrothermal medium heat exchanger 115 rises following the increase of the return temperature Twi. Since the circulation amount M _E of the water heat medium flowing through the heat medium heat exchanger 115 does not change at 6.0 L per minute, if the heat amount Q _E for heating the water heat medium in the water heat medium heat exchanger 115 is constant, the number This is because the temperature difference Two-Twi is constant from the relationship of 1.

In the conventional heat pump hot water heater, the frequency of the compressor of the heat pump cycle is mainly controlled so that the going temperature Two becomes the target going temperature Two set by the user. If forward as described above temperature Two rises, lowers the frequency of the compressor, the water heat medium heat exchanger 115 lowers the amount of heat Q _E for heating the hydrothermal medium, performs a control to reduce the forward temperature Two . After sufficient time has elapsed, the frequency of the compressor is lowered until Q _E = Q _d , and the forward temperature Two is maintained at the target forward temperature Twot.

On the other hand, the temperature Twi _d hydrothermal medium flowing out of the indoor radiator 125d and remains elevated, after sufficient time has elapsed, the temperature difference Two-Twi _d based on the number 2, 1/4 It becomes. That is, the return temperature Twi rises and approaches the forward temperature Two. As a result, the condensation temperature in the heat pump cycle becomes high and the cycle efficiency is deteriorated.

  In order to avoid such a situation, there is a technique for improving the efficiency of the heat pump hot water heater by using a circulation pump that can control the circulation flow rate by driving a DC power source (see, for example, Patent Document 1 and Patent Document 2).

  Patent Document 1 discloses a method for controlling the rotational speed of a circulation pump so that a forward return temperature difference Two-Twi, which is a difference between a forward temperature Two and a return temperature Twi of the hydrothermal medium, is within a predetermined range. Has been.

  In Patent Document 1, an excessive increase in the return temperature Twi is suppressed, that is, an excessive increase in the refrigerant condensation temperature in the hydrothermal heat exchanger is suppressed, cycle efficiency deterioration is prevented, and the power consumption of the circulation pump is reduced. It is described that it can be reduced.

FIG. 5 shows a control flow of the circulation pump of this control method. When the return temperature difference ΔTa (= Two−Tw) is calculated (step S04) and the return temperature difference is smaller than a predetermined value (4K), or when the target return temperature Two is not secured, the water heat The circulation pump is controlled so as to reduce the circulation flow rate of the medium (step S09). On the contrary, if the return temperature difference is equal to or greater than the predetermined value (20K) even if the forward temperature Two is close to the target forward temperature Two, the circulating flow rate of the hydrothermal medium is increased. The circulation pump is controlled (step S10).

  That is, only when the return temperature difference is within a predetermined range (4K or more and less than 20K) and the target return temperature Two is ensured, the circulating flow rate of the hydrothermal medium is maintained (step S08).

  In Patent Document 2, the frequency of the compressor of the heat pump cycle in the heat pump cycle is controlled so that the forward temperature Two of the hydrothermal medium becomes the target forward temperature (Twot). A method of controlling the circulation pump so that Two-Twi becomes a target return temperature difference is disclosed.

  FIG. 6 shows a control flow of the circulation pump of this control method. The return temperature difference ΔTa (= Two−Tw) is calculated (step S24), and if the return temperature difference ΔTa is larger than the target return temperature difference ΔTat for a predetermined time, the temperature difference is too large. Therefore, the circulation pump is controlled to increase the circulation flow rate of the water heating medium (step S26).

  On the other hand, when the return / return temperature difference ΔTa is smaller than the target return / return temperature difference ΔTat or the return / return temperature difference ΔTa is larger than the target return / return temperature difference ΔTat for a predetermined time, the return temperature Two The relationship with the target going temperature Twot is examined (step S27).

  In a state in which the state where the going temperature Two is equal to or higher than the target going temperature Two is maintained for a predetermined time, the circulation pump is controlled so as to reduce the circulation flow rate of the hydrothermal medium (step S28). Conversely, in the state where the forward temperature Two is lower than the target forward temperature Two or the state where the forward temperature Two is equal to or higher than the target forward temperature Thot has not been maintained for a predetermined time, the circulating flow rate of the hydrothermal medium is left unchanged.

  In step S26 and step S28, PI control is used for controlling the circulation pump. Moreover, the process after S25 is performed for every fixed time, and the circulation flow rate of a hydrothermal medium is deferred in the meantime.

  In Patent Document 2, as in Patent Document 1, excessive increase in the refrigerant condensing temperature in the hydrothermal heat exchanger is suppressed, cycle efficiency deterioration is prevented, and power consumption of the circulation pump can be reduced.

JP 2009-287895 A JP 2010-196946 A

  Patent Document 1 only describes the control of the rotational speed of the circulation pump, and does not describe the relationship with the frequency control of the compressor of the heat pump cycle. When such control is performed, in the above-described example, the forward temperature Two may not be maintained at the target forward temperature Two.

From the state where the water heat medium is supplied to all four indoor radiators (125a to 125d), the water supply of the water heat medium to the three indoor heat radiators (125a to 125c) is stopped by the user setting. immediately after, as described above, the temperature Twi _d hydrothermal medium flowing out of the indoor radiator 125d increases, since the increased return temperature Twi flowing into the water heat medium heat exchanger 115, the water heating medium heat exchanger The going-out temperature Two after passing through 115 also rises.

In the control method of Patent Document 1, the circulation pump is controlled so as to lower the circulation flow rate of the hydrothermal medium by increasing the going-out temperature Two (step S09). As a result, the circulation amount M _E hydrothermal medium flowing through the water heat medium heat exchanger 115 is reduced.

Meanwhile, since the amount of heat Q _E for heating the hydrothermal medium in the hydrothermal medium heat exchanger 115 is constant without adjusting, from the number 1, the forward return temperature difference Two-Twi expands. At this time, since the return temperature Twi tends to increase, the forward temperature Two further increases, and there is a possibility that the return temperature Twi may greatly deviate from the target forward temperature Twot.

  Patent Document 2 describes that the control of the rotational speed of the circulation pump and the frequency control of the compressor of the heat pump cycle are performed in parallel. However, there is no description about the relationship between the control time intervals between the two, and there is a possibility that the control becomes unstable.

Referring to the previous example, stopping the water supply of the water heating medium into three indoor radiator (125a-125c), the amount of heat Q _E for heating the hydrothermal medium in the hydrothermal medium heat exchanger 115 is clearly excessive It is. Therefore, in the frequency control of the compressor of the heat pump cycle, when the forward temperature Two rises and begins to deviate from the target forward temperature Two, a relatively short time (10 to 30 seconds) is maintained so that the forward temperature Two can maintain the target forward temperature Twot. ) Need to work.

  As described above, when only the compressor frequency is decreased, the increase in the going temperature Two is suppressed and starts to decrease. On the other hand, the return temperature Twi gradually increases, and the return temperature difference Two-Twi gradually decreases.

  If the “certain time” in step S23 in FIG. 6 and the “predetermined time” in steps S25 and S27 are equal to or less than the time interval during which the frequency control of the compressor is performed, the PI control of the circulation pump 121 is performed. In this transient state, the influence of the compressor frequency control is reflected. Of course, the influence of the control of the circulation pump is reflected also in the frequency control of the compressor, and there is a possibility that the whole control becomes unstable.

  In order to eliminate the influence of the frequency control of the compressor, both the “certain time” in step S23 and the “predetermined time” in steps S25 and S27 need to be sufficiently long. In order to exert the energy saving effect by the control, it is better to set the time as short as possible. However, it is considered that the indoor radiators 125a to 125d have different sizes and the above transient state is different for each indoor radiator to be supplied with water. Then, it was necessary to clarify the specific setting method of the said time.

  An object of the present invention is to solve the above-described conventional problems, and particularly to provide a heat pump hot water heater that suppresses an increase in condensation temperature in a heat pump cycle and has high operation efficiency of the heat pump cycle, particularly when the indoor heating load is small. To do.

  In order to solve the above-mentioned conventional problems, the heat pump hot water heater of the present invention has a time variation amount of the return temperature that falls within the allowable temperature change range, and a time variation amount of the return temperature detected by the return temperature detection means returns. The flow rate of the hydrothermal medium is adjusted by the circulation pump so that the return temperature becomes the target return temperature only when the temperature change is within the allowable range and the difference between the forward temperature and the target forward temperature is within the allowable range of the forward temperature error. To do.

  As a result, while the forward temperature is maintained at the target forward temperature set by the user, even when the thermal load is suddenly reduced, the circulating flow rate of the water heating medium is lowered to suppress the return temperature from rising.

  ADVANTAGE OF THE INVENTION According to this invention, especially when an indoor heating load is small, the raise of the condensation temperature in a heat pump cycle can be suppressed reliably, and the heat pump hot water heater which implement | achieved the improvement of the operating efficiency of a heat pump cycle can be provided.

Control flow chart of circulation pump of heat pump hot water heater in Embodiment 1 of the present invention The figure which showed the time change of the frequency of the compressor, the number of rotations of the circulation pump, the going temperature, and the return temperature after starting the heat pump hot water heater The figure which showed the time change of the frequency of a compressor, the number of rotations of a circulation pump, the going temperature, and the return temperature after stopping water supply to the indoor radiator of the same part Configuration diagram of the heat pump hot water heater Conventional circulation pump control flowchart Control flow chart of another conventional circulation pump

  According to the first aspect of the present invention, the time change amount of the return temperature is in the return temperature change allowable range, the time change amount of the return temperature detected by the return temperature detecting means is in the return temperature change allowable range, and the return temperature and the target The flow rate of the water heating medium is adjusted by the circulation pump so that the return temperature becomes the target return temperature only when the difference from the return temperature is within the allowable range of the return temperature error and the frequency of the compressor becomes constant.

  For this reason, the control of the compressor and the control of the circulation pump do not interfere with each other, and each control does not become unstable, and the return flow rate Twi is increased by lowering the circulating flow rate of the hydrothermal medium. It is possible to reliably suppress, prevent an increase in the condensation temperature, prevent a decrease in the efficiency of the heat pump cycle, and reduce the operating power of the circulation pump.

  In the second invention, an upper limit is set for the adjustment amount of the flow rate of the hydrothermal medium by the circulation pump, and in addition to the effect of the first invention, an excessive change in the going temperature when the circulation pump is controlled is prevented. can do.

  In the third invention, the target return temperature in the first or second invention is selected from the first temperature range of 34 ° C. or higher and 45 ° C. or lower in which the thermal stimulation sensed by the human skin temperature receptor is dominant. I am doing so. For this reason, especially in the case where the indoor radiator is a floor heating panel, it is possible to prevent an increase in the condensing temperature and prevent a decrease in the efficiency of the heat pump cycle, as long as it is not touched and feels uncomfortable. The operating power of the circulation pump can be reduced.

  In a fourth aspect based on the third aspect, when the temperature difference obtained by subtracting the target return temperature from the target forward temperature is less than the predetermined temperature difference, the temperature obtained by subtracting the predetermined temperature difference from the target forward temperature is set as the target return temperature. It is temperature.

  For this reason, even when the target outbound temperature is set to a relatively low temperature of 40 ° C. or less, such as in the case of preheating operation, it is possible to prevent the return temperature from approaching the outbound temperature and prevent a decrease in efficiency of the heat pump cycle. it can. Even in this case, the driving power of the circulation pump can be reduced.

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

(Embodiment 1)
FIG. 4 is a configuration diagram of a heat pump hot water heater 100 that is an object of the present invention. The heat pump hot water heater 100 includes a heat pump cycle 110, a water heating medium cycle 120, and a control unit 130.

  The heat pump cycle 110 sucks and compresses a refrigerant in a gaseous state, discharges a high-temperature and high-pressure refrigerant, an air heat exchanger 112 that collects heat from outdoor air, and forcibly uses outdoor air as an air heat exchanger 112. The air heat exchanger fan 113 to be introduced into the refrigerant, the refrigerant flow rate adjusting valve 114 for adjusting the flow rate of the refrigerant, and the water heat medium heat exchanger 115 for performing heat exchange between the refrigerant and the water heat medium.

  On the other hand, the water heat medium cycle 120 is connected to the water heat medium heat exchanger 115 and circulates the water heat medium in the water heat medium cycle 120, the circulation pump 121, the buffer tank 122 storing the water heat medium, and four units. The indoor radiators 125a to 125d and the on-off valve 123 that controls the supply of the hydrothermal medium to the individual indoor radiators 125 are configured.

  The refrigerant of the heat pump cycle 110 and the hydrothermal medium of the hydrothermal medium cycle 120 are independent of each other and do not mix, but are configured to be able to exchange heat via the hydrothermal medium heat exchanger 115. As the water heat medium heat exchanger 115, a double tube heat exchanger or a plate heat exchanger is used. The circulation pump 121 driven by a DC power supply has an impeller, and the circulation flow rate of the water heat medium in the water heat medium cycle 120 can be changed by PWM control of the rotation speed of the impeller. .

  In the water heat medium cycle 120, a forward temperature detection sensor that measures the forward temperature Two of the water heat medium from the water heat medium heat exchanger 115 toward the indoor radiators 125 a to 125 d is provided on the outlet side of the water heat medium heat exchanger 115. 126 is installed. In addition, a return temperature detection sensor 127 that measures the return temperature Twi of the water heat medium returning from the indoor radiators 125 a to 125 d to the water heat medium exchanger 115 is installed on the inlet side of the water heat medium heat exchanger 115. .

  The control unit 130 is a control program incorporated in a microcomputer (not shown), the outdoor temperature, the discharge temperature of the compressor 111 (both detected by a temperature sensor not shown), the forward temperature Two detected by the forward temperature detection sensor 126, The return temperature Twi detected by the return temperature detection sensor 127 is acquired and connected to the frequency of the compressor 111, the rotation speed of the air heat exchanger fan 113, the opening of the refrigerant flow rate adjustment valve 114, and the indoor radiators 125a to 125d to be used. The opening degree of the open / close valve 123 and the rotational speed of the circulation pump 121 are controlled.

  Remote controller 124 and indoor radiators 125a to 125d are both installed in a room to be heated. Even if four remote controllers 124 are connected to control indoor radiators 125a to 125d individually, two or three remote controllers 124 are connected to control every few of indoor radiators 125a to 125d. Alternatively, one unit may be connected to control all of the indoor radiators 125a to 125d.

By operating the remote controller 124, the heat pump hot water heater 100 is operated, and the heated hydrothermal medium is conveyed to the indoor radiators 125a to 125d by the circulation pump 121 to dissipate heat, thereby heating the room. As the indoor radiator 125, a floor heating panel embedded in the floor for radiant heating, a radiator installed on the indoor wall surface for radiant heating, and a blower are used to forcibly supply the heat of the indoor radiator 125 into the room. Use a fancon vector.

  The user of the heat pump hot water heater 100 sets the target going temperature Twoot using the remote control 124. Or when using a floor heating panel for the indoor radiator 125, for example, the height level of floor surface temperature is set. In this case, the control unit 130 calculates and holds the target forward temperature Twot according to the heating intensity level set by the user.

  Further, the user of the heat pump hot water heater 100 sets the target return temperature Twit using the remote controller 124. The target return temperature Twit is not necessarily set by the user.

  Next, the operation of the heat pump hot water heater 100 will be described. FIG. 1 is a flowchart illustrating a control operation for the circulation pump 121 of the control unit 130 in the first embodiment of the present invention.

  First, after starting the heat pump hot water heater 100 and starting to convey the heated hydrothermal medium to the indoor radiators 125a to 125d all at once, the forward temperature Two becomes the target forward temperature Two, and the return temperature Twi becomes the target return temperature. A control operation up to Twit will be described.

  When the user performs a driving start operation (step S001) with the remote controller 124, the remote controller 124 transmits the target forward temperature Two set by the user to the control unit 130 together with the driving start command. The control unit 130 holds the received target going temperature Twot. When the remote controller 124 transmits the heating intensity level to the control unit 130, the control unit 130 calculates and holds the target forward temperature Twot according to the received heating intensity level (step S002).

  Next, in step S003, the remote control 124 transmits the target return temperature Twit set by the user to the control unit 130. The control unit 130 holds the received target return temperature Twit. When the user does not set or cannot set the target return temperature Twit on the remote controller 124, the control unit 130 automatically sets the target return temperature Twit.

  In human skin, there is a temperature receptor composed of a cold receptor and a warm receptor. In general, when the temperature touched by the skin is 32.5 ° C. to 33.5 ° C., the stimulation received by the cold / heat receptor is about the same, resulting in a dead temperature that does not feel hot or cold. At 34 ° C. to 45 ° C., only the skin thermoreceptor feels warm when stimulated, but when it exceeds 36 ° C., the intensity of the stimulation decreases with increasing temperature. When the temperature exceeds 45 ° C., the cold receptors in the skin are also stimulated and feel hot.

  Considering the above knowledge and the fact that the return temperature Twi is slightly higher than the lowest temperature on the surface of the indoor radiator 125, the target return temperature Twit is stimulated only by the human skin temperature receptor. It is desirable to set the temperature to 34 ° C. to 45 ° C. which feels warm. Furthermore, since the heat pump cycle is more efficient when the condensation temperature is lowered, it is more effective to make the return temperature Twi as low as possible. Considering that when the temperature touched by the skin exceeds 36 ° C., the intensity of stimulation of the skin temperature receptor decreases with increasing temperature, the target return temperature Twit is most preferably set to 34 ° C. to 36 ° C.

Further, in the residual heat operation performed when the user leaves the room, the target going temperature Twot is set to be relatively low (40 ° C. or lower). In this case, the temperature difference between the target forward temperature Twit and the target return temperature Twit selected from the range of 34 to 45 ° C. becomes small, and the efficiency of the heat pump cycle during the remaining heat operation may be deteriorated. For example, when the target forward temperature Twit is set to 35 ° C., the lower limit value of the target return temperature Twit is 34 ° C., and the temperature difference between them is only 1K. In such a case, a target return temperature Twit is set to a predetermined value, for example, 30 ° C., which is 5K lower than the target forward temperature Twit = 35 ° C.

  The predetermined value may be set by the user using the remote controller 124.

  When the target going temperature Twot and the target return temperature Twit are set, the control unit 130 starts the operation of the compressor 111, the air heat exchanger fan 113, the refrigerant flow rate adjustment valve 114, and the circulation pump 121.

  With respect to the rotation speed Fs of the circulation pump 121, the circulation flow rate control at the time of start-up that is gradually increased from Fs = 0 is performed. The start-up circulation flow rate control is performed until a predetermined time, for example, 10 minutes elapses after the start of the circulation pump 121 (step S003). Generally, the rotational speed Fs is increased in three to five stages so that the rotational speed Fs of the circulation pump 121 reaches the maximum rotational speed within the predetermined time (step S006).

  The reason for carrying out the startup circulation flow rate control is that if the rotation speed Fs of the circulation pump 121 is suddenly increased immediately after the heat pump cycle 110 is started, the cooled water heat medium staying in the indoor radiator 125 becomes hydrothermal. A large amount flows to the medium heat exchanger 115, and the rise of the refrigerant condensing temperature on the heat pump cycle 110 side in the water heat medium heat exchanger 115 is delayed, and it may take time to increase the temperature of the indoor radiator 125. Because.

  Simultaneously with the above-described circulation flow rate control at startup, the frequency Fc of the compressor 111 is also controlled. The most basic method of this control is P control (proportional control) that adjusts the frequency Fc of the compressor 111 so that the forward temperature Two becomes the target forward temperature Twot.

  In the P control (proportional control) of the frequency Fc of the compressor 111, Kp1 × (Two−Twot) obtained by multiplying the temperature difference Two−Twot between the forward temperature Two and the target forward temperature Two by the proportional gain Kp1 is expressed by the compressor 111. The frequency Fc is a value to be corrected (steps S007 and S008).

The value of the proportional gain Kp1 takes a negative value so that the following effects can be obtained. That is, when the Two-Twot> 0, by reducing the frequency Fc of the compressor 111, reducing the amount of heat _{Q E} for heating the hydrothermal medium in the hydrothermal medium heat exchanger 115. Conversely, when the Two-Twot <0, increases the frequency of the compressor 111, increase the heat quantity _{Q E.}

  As a method for controlling the frequency Fc of the compressor 111, so-called PI control may be used instead of P control. In the PI control, Ki1 × ∫ (Two−Twot) dt obtained by multiplying the time integral of the temperature difference Two−Twot between the forward temperature Two and the target forward temperature Two by the integral gain Ki1, and Kp1 × (P control (proportional control) Kp1 × ( The frequency of the compressor 111 is corrected using the sum of “Two−Twot”.

  In the P control, there is a possibility that a residual deviation (offset) may occur between the forward temperature Two and the target forward temperature Two even when the forward temperature Two no longer changes (steady state). However, when the PI control in which the proportional gain Kp and the integral gain Ki are appropriately set is used, the forward temperature Two can be reliably converged to the target forward temperature Two.

In addition, the control part 130 also controls the rotation speed of the air heat exchanger fan 113 and the opening degree of the refrigerant | coolant flow rate adjustment valve 114, respectively, during the starting circulation flow rate control. For example, the rotational speed of the air heat exchanger fan 113 is controlled according to the frequency Fc of the compressor 111, and the refrigerant flow rate adjustment valve 11 is controlled.
The opening degree of 4 is controlled according to the target forward temperature Twot.

  Now, when the start-up circulation flow rate control ends after a predetermined time (for example, 10 minutes), the rotation speed Fs of the circulation pump 121 reaches the maximum rotation speed. From this time point, the control unit 130 starts monitoring whether the change amount ΔTwo of the forward temperature Two and the change amount ΔTwi of the return temperature Twi satisfy Equations 3 and 4, respectively (Step S009 and Step S010). ).

(Equation 3) | ΔTwo | <ε1
(Equation 4) | ΔTwi | <ε2
Note that ε1 in Equation 3 indicates an allowable temperature change range, ε2 in Equation 4 indicates a return temperature change allowable range, and each value is, for example, 0.5K.

  The change amount ΔTwo of the going temperature Two and the change amount ΔTwi of the return temperature Twi may be a difference between the current measurement value and the measurement value before a predetermined time (for example, 5 minutes) from the present time, or within a predetermined time (for example, A value obtained by subtracting the minimum value from the maximum value of the respective measurement values may be used.

  When Equations 3 and 4 are not satisfied at the same time, the processing of Step S007 and Step S008, that is, the control of the frequency Fc of the compressor 111 is performed. On the other hand, when Equations 3 and 4 are satisfied at the same time, the operation state of the heat pump hot water heater 100 is regarded as being in a steady state, the process proceeds to Step S011, and the forward temperature Two becomes the target forward temperature Twot. Determine if it has reached.

  In step S011, it is checked whether or not the difference between the going temperature Two and the target going temperature Two satisfies Equation 5. In Equation 5, ε3 is an allowable temperature error range, and this value is, for example, 0.3K.

(Equation 5) | Two-Twot | <ε3
If the number 5 is not satisfied in step S011, the room where the indoor radiator 125 is dissipating heat may not be sufficiently heated, so the processing in steps S007 and S008, that is, the frequency of the compressor 111 Continue to control Fc.

  On the other hand, when the number 5 is satisfied, it is determined that the room where the indoor radiator 125 is radiating heat is sufficiently warm, and the process proceeds to step S012 to control the rotational speed Fs of the circulation pump 121. . The most basic method of this control is P control (proportional control) that adjusts the rotational speed Fs of the circulation pump 121 so that the return temperature Twi becomes the target forward temperature Twit.

  In the P control (proportional control) for adjusting the rotation speed Fs of the circulation pump 121, Kp2 × (Twi−Twit) obtained by multiplying the temperature difference Twi−Twit between the return temperature Twi and the target return temperature Twit by the proportional gain Kp2 is obtained. The rotation speed Fs of the circulation pump 121 is set to a value to be corrected (Steps S012 and S013).

  The value of the proportional gain Kp2 takes a negative value so that the following effects can be obtained. That is, when Twi-Twit> 0, the rotational speed Fs of the circulation pump 121 is decreased, and the temperature difference from the forward temperature Two is increased to decrease Twi. Conversely, when Twi−Twit <0, the rotational speed Fs of the circulation pump 121 is increased, and the temperature difference from the forward temperature Two is reduced to increase Twi.

As a method of controlling the rotational speed Fs of the circulation pump 121, a so-called PI is used instead of the P control.
Control may be used. In the PI control, Ki2 × ∫ (Twi−Twit) dt obtained by multiplying the time integral of the temperature difference Twi−Twit between the return temperature Twi and the target return temperature Twit by the integral gain Ki2, and Kp2 × (P control (proportional control) Kp2 × (proportional control). The rotational speed Fs of the circulation pump 121 is corrected using the sum of (Twi−Twit).

  In the P control, there is a possibility that a residual deviation (offset) may occur between the return temperature Twi and the target return temperature Twit even when the return temperature Twi does not change (steady state). However, when the PI control in which the proportional gain Kp2 and the integral gain Ki2 are appropriately set is used, the return temperature Twi can be reliably converged to the target return temperature Twit.

  FIG. 2 shows that the frequency Fc of the compressor 111 after the heat pump hot water heater 100 is started and the forward temperature Two and the return temperature Twi are substantially constant and the forward temperature Two reaches the target forward temperature Twot. The control of the rotational speed Fs of the circulation pump 121 and the outline of the time change of the forward temperature Two and the return temperature Twi accompanying these controls are shown. Note that the target forward temperature Twit is set to 50 ° C., and the target return temperature Twit is set to 35 ° C.

  In addition, at time T1, the return temperature Twi reaches 40 ° C., and after time T1, the amount of heat (heat load) radiated in the indoor radiator 125 is assumed to be constant.

  At time T1, the control unit 130 determines that the forward temperature Two and the return temperature Twi are in a steady state where the return temperature Twi is substantially constant, and that the forward temperature Two has reached the target forward temperature Two (steps S009 to S011). The number of rotations Fs of the circulation pump 121 is controlled (steps S012 and S013). Since the return temperature Twi (= 40 ° C.) at the time T1 is higher than the target return temperature Twit (= 35 ° C.), the rotational speed Fs of the circulation pump 121 is lowered to lower the return temperature Twi.

At this point, since the still frequency Fc of the compressor 111 is not controlled, the amount of heat Q _E for heating the hydrothermal medium in the hydrothermal medium heat exchanger 115 is not changed. Therefore, only the rotation speed Fs of the circulation pump 121 is reduced, and the return temperature difference Two-Twi is expanded from the relationship of Equation 1 . Actually, since the change in the temperature Twi of the water heat medium returning from the indoor radiator 125 having a few liters of the water heat medium is slow, first, the forward temperature Two starts to rise rapidly.

  Note that the rapid increase in the forward temperature Two is proportional to the amount of change in the rotational speed Fs of the circulation pump 121. If this amount of change is too large, the increase in the going temperature Two becomes 2 to 3K or more. In particular, when a floor heating panel is used as the indoor radiator 125, a change in the temperature of the floor surface becomes large, and the user's comfort may be impaired.

  Therefore, it is desirable to provide an upper limit for the amount of change in the rotational speed Fs of the circulation pump 121 to suppress an increase in the going temperature Two. The upper limit value is set to 10 to 20% of the current rotational speed Fs of the circulation pump 121, for example.

  When the going temperature Two suddenly rises, Equation 3 is not satisfied in step S009, and the process shifts to control of the frequency Fc of the compressor 111 (steps S007 and S008). Then, the control unit 130 decreases the frequency Fc of the compressor 111 in order to return the going temperature Two to the target going temperature Twot. As a result, the increase in the forward temperature Two stops and conversely begins to decrease.

However, since the amount of heat (heat load) radiated by the indoor radiator 125 is constant, the going temperature Two becomes lower than the target going temperature Two due to the influence of decreasing the frequency Fc of the compressor 111. Therefore, the control unit 130 increases the frequency Fc of the compressor 111 again in order to return the going temperature Two to the target going temperature Two (steps S007 and S00).
8).

  On the other hand, the return temperature Twi changes finely under the influence of the rapid increase in the going temperature Two as described above, but when viewed in a span of several minutes, the rotation speed Fs of the circulation pump 121 is reduced. It gradually decreases under the influence of the effect of increasing the return temperature difference Two-Twi and the control of the frequency Fc of the compressor 111 that attempts to return the return temperature Two to the target return temperature Twot.

  Thus, at time T3 when a certain amount of time has elapsed, the frequency Fc of the compressor 111 is the same as that before time T1, and only the rotational speed Fs of the circulation pump 121 is decreased. Then, the forward temperature Two and the return temperature Twi become substantially constant values, and the forward temperature Two reaches the target forward temperature Two. However, the return temperature Twi is closer to the target return temperature Twit (= 35 ° C.) than 40 ° C. at time T1.

  The control unit 130 performs control so as to decrease the rotational speed Fs of the circulation pump 121 again at time T3. The control of the frequency Fc of the compressor 111 and the change in the forward temperature Two and the return temperature Twi after the rotation speed Fs of the circulation pump 121 is controlled are the same as described above. Thus, at time T5 when a certain amount of time has elapsed, the return temperature Twi is closer to the target return temperature Twit (35 ° C.) than at time T3.

  As described above, the control unit 130 stabilizes the heat pump cycle 110 by activating the heat pump hot water heater 100 and gradually increasing the circulation flow rate of the hydrothermal medium in the startup circulation amount control (step S003). First, only the control of the frequency Fc of the compressor 111 is performed until the forward temperature Two and the return temperature Twi are substantially constant and the forward temperature Two reaches the target forward temperature Two.

  When the forward temperature Two and the return temperature Twi become substantially constant values, and the forward temperature Two reaches the target forward temperature Two, the frequency Fc of the compressor 111 hardly changes. The controller 130 controls the rotational speed Fs of the circulation pump 121 so that the return temperature Twi becomes the target return temperature Twit only when this state is reached.

  When the rotational speed Fs of the circulation pump 121 is controlled, the forward temperature Two exceeds the forward temperature allowable change range ε1. Therefore, the control unit 130 performs only the control of the frequency Fc of the compressor 111 again until the temporal change of the forward temperature Two and the return temperature Twi becomes small.

  As described above, in the present embodiment, the frequency Fc of the compressor 111 and the rotation speed Fs of the circulation pump 121 are controlled while monitoring the respective values and temporal changes of the forward temperature Two and the return temperature Twi. Are switched so that they are not affected by each other's control, so that each control does not become unstable.

  As a result, it is possible to reliably suppress an increase in the return temperature Twi, prevent an increase in the condensation temperature, prevent a decrease in the efficiency of the heat pump cycle, and reduce the operating power of the circulation pump.

  Next, the water heating medium is sent to all four indoor radiators (125a to 125d), the return temperature Two and the return temperature Twi are substantially constant, and the return temperature Two is the target return temperature Twot. The operation of the heat pump hot water heater 100 after the water supply of the hydrothermal medium to the three indoor radiators (125a to 125c) is stopped by the setting of the user from the state reached to the above will be described.

  FIG. 3 shows how the frequency Fc of the compressor 111 and the rotational speed Fs of the circulation pump 121 are controlled after stopping the water supply of the water heat medium to the three indoor radiators (125a to 125c). The outline of the time change of the going temperature Two and the return temperature Twi accompanying control is shown.

  As a precondition in FIG. 3, first, at time T6 when water supply of the water heat medium to the three indoor radiators 125a to 125c is stopped, the return temperature Two is set to the target return temperature Two (= 50 ° C.), and the return temperature Twit. Is the target return temperature Twit (= 35 ° C.).

  Next, it is assumed that the indoor radiators 125a to 125d are all the same. Assuming that the flow rate of the hydrothermal medium sent out by the circulation pump 121 at time T6 is 6 L / min, before the time T6, the flow rate of the hydrothermal medium sent per indoor radiator is 6.0 L / min. /4=1.5L. And after the time T6, the circulation amount of the hydrothermal medium in the remaining indoor radiator 125d significantly increases to 6.0 L / min, which is four times as much.

  Furthermore, it is assumed that the amount of heat (heat load) radiated in the four indoor radiators 125a to 125d before time T6 is the same. That is, after time T6, the amount of heat radiated in the indoor radiator 125d (thermal load) is ¼ of the total amount of heat radiated (thermal load) in the indoor radiators 125a to 125d before time T6. .

Next, FIG. 3 will be described. When water supply of the water heat medium to the three indoor radiators 125a to 125c is stopped at time T6, the circulation amount M _d of the water heat medium flowing through the indoor radiator 125d is four times as large as 6.0 L per minute. To increase. In response to this effect, the temperature Twi _d hydrothermal medium flowing out of the indoor radiator 125d gradually begins to rise. This phenomenon is based on the number 2 of the equation, the temperature Twi _d is stepwise jump are not.

The reason is, there is hydrothermal medium number L in water heating medium in the pipe of the indoor radiator 125d, even if the increased circulation amount M _d hydrothermal medium, at time T6, the indoor radiator in 125d as hydrothermal medium present in the position closer to the outlet pipe of the unaffected temperature drop of the heat flow medium flowing through the pipe by increasing the circulation amount M _d hydrothermal medium is reduced, and flows out from the indoor radiator 125d Because.

Next, the forward temperature Two of the hydrothermal medium after being heated by the hydrothermal medium heat exchanger 115 rises following the increase of the return temperature Twi. Since the circulation amount M _E of the water heat medium flowing through the heat medium heat exchanger 115 does not change at 6.0 L per minute, if the heat amount Q _E for heating the water heat medium in the water heat medium heat exchanger 115 is constant, the number This is because the temperature difference Two-Twi is constant from the relationship of 1.

  In this state, the control unit 130 controls the frequency Fc of the compressor 111 (steps S007 and S008). Then, the frequency Fc of the compressor 111 is lowered in order to return the going temperature Two to the target going temperature Twot. As a result, the increase in the forward temperature Two stops and conversely begins to decrease.

If the proportional gain Kp1 or the integral gain Ki1 is appropriately set, the forward temperature Two becomes the target forward temperature Two after a certain period of time (time T7 in FIG. 3). The frequency Fc of the compressor 111, the time T6 previously, in the hydrothermal medium heat exchanger 115 was heated hydrothermal medium heat Q _E is settled to frequencies of 1/4.

  On the other hand, the return temperature Twi is affected by the temporary increase in the going temperature Two and sometimes rises excessively. However, at the time T7, the return temperature difference Two−Twi is ¼ before the time T6. It is settled at the temperature. Since Two = Twot = 50 ° C. and Two−Twi = (50−35) /4=3.75K, Twi is 50−3.75 = about 46.3 ° C.

  Subsequent control of the control unit 130 is exactly the same as the above-described control at startup. That is, it is monitored whether or not the forward temperature Two and the return temperature Twi are in a steady state where the return temperature Twi is substantially constant, and the forward temperature Two has reached the target forward temperature Two (steps S009 to S011). If it satisfies, the rotational speed Fs of the circulation pump 121 is controlled (steps S012 and S013). If not satisfied, only the control of the frequency Fc of the compressor 111 (steps S007 and S008) is performed.

  That is, according to the present embodiment, even if there is a sudden drop in the heat load, such as stopping the water supply of water to some of the indoor radiators 125, the forward temperature Two and the return temperature Twi In order to switch between the control of the frequency Fc of the compressor 111 and the control of the rotational speed Fs of the circulation pump 121 while monitoring each value and time change so as not to be affected by the mutual control, Each control does not become unstable.

  As a result, it is possible to reliably suppress an increase in the return temperature Twi, prevent an increase in the condensation temperature, prevent a decrease in the efficiency of the heat pump cycle, and reduce the operating power of the circulation pump.

  As described above, in the heat pump hot water heater according to the present invention, the water heat medium heated in the water heat medium heat exchanger from the refrigerant of the heat pump cycle is conveyed to the indoor radiator by the circulation pump, and the room is heated. Even if there is a sudden decrease in heat load, the efficiency of the heat pump cycle can be prevented from decreasing and the operating power of the circulation pump can be reduced, so that it can be applied to a heat pump hot water heater with a low running cost.

DESCRIPTION OF SYMBOLS 100 Heat pump hot water heater 110 Heat pump cycle 111 Compressor 112 Air heat exchanger 113 Air heat exchanger fan 114 Refrigerant flow rate adjustment valve 115 Water heat medium heat exchanger 120 Water heat medium cycle 121 Circulation pump 122 Buffer tank 123 On-off valve 124 Remote control 125 Indoor radiator 126 Outward temperature detection sensor 127 Return temperature detection sensor 130 Control unit

Claims (4)

A heat pump cycle composed of a compressor, a heat medium heat exchanger for exchanging heat between the refrigerant and the heat medium, an expansion valve, and a heat source side heat exchanger, and indoor heat radiation for heating by the heat medium. A circulation pump that circulates the heat medium between the heat medium heat exchanger and the indoor radiator, and a temperature sensor that detects the temperature of the heat medium from the heat medium heat exchanger toward the indoor radiator. Temperature detection means and return temperature detection means for detecting the temperature of the heat medium returning from the indoor radiator to the heat medium heat exchanger, and the forward temperature detected by the forward temperature detection means is a target forward temperature. The operation frequency of the compressor is controlled so that the amount of time change of the forward temperature is within the allowable temperature change range, and the amount of time change of the return temperature detected by the return temperature detecting means is the return temperature change. Enter the allowable range, Heat pump hot water heating, wherein the flow rate of the heat medium is adjusted by the circulation pump so that the return temperature becomes the target return temperature when the difference from the reference temperature is within the allowable temperature error tolerance range Machine. The heat pump hot water heater according to claim 1, wherein an upper limit value is provided for an adjustment amount of the flow rate of the heat medium by the circulation pump. The heat pump hot water heater according to claim 1 or 2, wherein the target return temperature is selected from a first temperature range of 34 ° C or higher and 45 ° C or lower. The temperature obtained by subtracting the predetermined temperature difference from the target forward temperature is set as the target return temperature when a temperature difference obtained by subtracting the target return temperature from the target forward temperature is less than a predetermined temperature difference. 3. A heat pump hot water heater according to 3.