JP5582059B2 - 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.

  The present invention solves the above-mentioned conventional problem, while holding the forward temperature at the target forward temperature, suppressing an increase in the return temperature, particularly when the indoor heating load is small, suppressing an increase in the condensation temperature in the heat pump cycle, An object of the present invention is to provide a heat pump hot water heater having high operation efficiency of a heat pump cycle.

In order to solve the above-mentioned conventional problems, the heat pump hot water heater of the present invention controls the operating frequency of the compressor so that the forward temperature becomes the target forward temperature, and the water is exchanged with the heat transfer medium heat exchanger. When the number of indoor radiators that circulate the heat medium is reduced from N1 to N2, the circulation pump is controlled so that the flow rate of the hydrothermal medium before the change is multiplied by N2 / N1. . As a result, the number of indoor radiators that circulate the water heat medium to and from the heat medium heat exchanger is reduced by the user's settings, and the user sets the outgoing temperature even when the heat load drops sharply. While maintaining the target air temperature, the circulating flow rate of the water heating medium is lowered to suppress the return temperature from rising.

  According to the present invention, while maintaining the forward temperature at the target forward temperature, the increase in the return temperature is suppressed, and particularly when the indoor heating load is small, the increase in the condensation temperature in the heat pump cycle is suppressed, and the operation efficiency of the heat pump cycle is high. A heat pump hot water heater 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 Relationship diagram between the flow rate of water heating medium and pressure loss and the relationship between flow rate and pressure of water heating medium delivered by the circulation pump when supplying a water heating medium to the indoor radiator Control flowchart of circulation pump of heat pump hot water heater in Embodiment 3 of the present invention Configuration diagram of the heat pump hot water heater Conventional circulation pump control flowchart Control flow chart of another conventional circulation pump

In the first invention, when the number of indoor radiators supplying the water heat medium is reduced from N1 to N2 while controlling the operating frequency of the compressor so that the going temperature becomes the target going temperature, the water before the change is changed. The circulating pump is controlled so that the flow rate of the heat medium is multiplied by N2 / N1.

  For this reason, when the number of indoor radiators that supply the water heat medium decreases and the heat load decreases sharply due to user settings, the flow rate of the water heat medium is suddenly decreased to increase the return temperature. Immediately suppresses and prevents an increase in the condensation temperature of the heat pump cycle. As a result, it is possible to prevent a reduction in the efficiency of the heat pump cycle and reduce the operating power of the circulation pump.

In the second aspect of the invention, the number of indoor radiators that supply the water heating medium changes, and the sum of the volumes of the water heating medium held in the internal piping of the indoor radiator that supplies the water heating medium decreases from L1 to L2. In this case, the circulation pump is controlled so that the flow rate of the hydrothermal medium before the change is multiplied by L2 / L1.

  For this reason, in particular, when the number of indoor radiators that supply the water heating medium is reduced due to user settings, and the thermal load is drastically reduced, the flow rate of the water heating medium is changed to the area of the indoor radiator and the internal Reduce rapidly to an amount that takes into account differences in piping specifications.

  For example, when the number of indoor radiators supplying the water heat medium is reduced from four to one, the remaining one indoor radiator is wide and the water heat medium holding amount is large. Set a larger flow rate. Conversely, if the area of the remaining one indoor radiator is small and the amount of the water heat medium is small, the flow rate of the water heat medium is set to be small.

  Therefore, according to the second aspect of the present invention, when the number of indoor radiators that supply the water heat medium decreases and the heat load rapidly decreases, the target flow rate of the water heat medium is set according to the user setting. As with the first aspect of the invention, it is possible to set appropriately, and as with the first aspect of the invention, the rise in the return temperature is immediately suppressed, the rise in the condensation temperature is prevented, the efficiency of the heat pump cycle is prevented from being lowered, and the circulation The driving power of the pump can be reduced.

  According to a third aspect of the present invention, when the number of indoor radiators that supply the water heat medium is reduced, the water heat medium is only used when the difference between the unwinding temperature and the target temperature is within the allowable temperature error range. It is judged that the room in which the indoor radiator is being supplied is sufficiently warm, and the flow rate of the water heating medium is reduced by the circulation pump.

  For this reason, when the user changes the setting so that the supply of the water heat medium to the indoor radiator in a room that is sufficiently warmed is stopped and the water heat medium is supplied only to the indoor radiator in a room that is not warm. In the third invention, the flow rate of the hydrothermal medium decreases, the going-out temperature temporarily rises, the frequency of the compressor decreases, and the amount of heat supplied to the indoor radiator decreases. Can prevent this.

  According to a fourth aspect of the present invention, when the number of indoor radiators that supply the water heat medium is reduced, an indoor radiator that supplies the water heat medium is installed when the return temperature before the decrease is equal to or higher than the target return temperature. The room is judged to be sufficiently warm, and the flow rate of the hydrothermal medium is reduced by a circulation pump.

  Although the target return temperature is lower than the target return temperature, it is set to a temperature at which it can be determined that the room in which the indoor radiator that supplies the hydrothermal medium is installed is sufficiently warm. When the return temperature is equal to or higher than the target return temperature, the temperature of the hydrothermal medium existing in the internal piping of each indoor radiator reaches at least the target return temperature, and the room where each indoor radiator is installed is sufficiently warm. Can be considered.

  For this reason, 4th invention can judge whether the room in which the indoor heat radiator which supplies the hydrothermal medium was installed is warm.

  In the fifth aspect of the invention, the target return temperature is selected from a first temperature range of 34 ° C. or higher and 45 ° C. or lower, in which the warm sensation sensed by the human skin temperature receptor is dominant.

  For this reason, especially when the indoor radiator is a floor heating panel, it can be determined whether or not the floor heating panel is warmed to the extent that it does not feel uncomfortable if it is cold to the touch.

  According to a sixth aspect of the present invention, when the number of indoor radiators that supply a water heat medium increases, the circulating pump is controlled so that the flow rate of the water heat medium is maximized, and the outgoing temperature is reduced to the maximum. .

  For this reason, when the number of indoor radiators that supply the water heat medium increases, it is possible to promptly increase the frequency of the compressor and quickly warm the indoor radiator that has newly started supplying the water heat medium. it can.

  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. 5 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. The indoor radiator 125 is forcibly supplied with heat from the indoor radiator 125 using a floor heating panel embedded in the floor for radiant heating, a radiator installed on the wall surface of the room for radiant heating, and a blower. 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. A specific value of the target return temperature Twit will be described later.

  Next, the operation of the heat pump hot water heater 100 will be described. FIG. 1 is a flowchart illustrating control operations for the compressor 111 and the circulation pump 121 of the control unit 130 in the first embodiment of the present invention.

  Hereinafter, the control operation of this embodiment will be described in order from step S001 using the flowchart of FIG.

  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.

  From the above, considering that the return temperature Twi is slightly higher than the lowest temperature of the surface of the indoor radiator 125, the target return temperature Twit is warm because only the human skin temperature receptor is stimulated. It is desirable that the temperature be 34 ° C to 45 ° C.

  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 remaining heat operation performed when the user leaves the room, the target going temperature Twot is set to a relatively low temperature, for example, 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). In general, 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 Fsmax 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 number of revolutions of the air heat exchanger fan 113 is controlled according to the frequency Fc of the compressor 111, and the opening degree of the refrigerant flow rate adjustment valve 114 is controlled according to the target forward temperature Twot.

  When the start-up circulation flow rate control ends after a predetermined time (for example, 10 minutes) has elapsed, the rotation speed Fs of the circulation pump 121 has reached the maximum rotation speed Fsmax. From this point of time, the control unit 130 starts monitoring the change in the number of indoor radiators that supply the water heat medium (S009) and monitoring the outgoing temperature Two (step S010) by the user's remote control 124 operation.

  In the present embodiment, as an example, a hydrothermal medium is supplied 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 A control operation after the supply of the hydrothermal medium to the three indoor radiators (125a to 125c) is stopped by the user's setting from the state where the target going temperature Twot has been reached will be described.

  FIG. 2 shows the time transition of the control of the frequency Fc of the compressor 111 and the rotational speed Fs of the circulation pump 121 in the above example, and the outline of the temporal change of the forward temperature Two and the return temperature Twi accompanying these controls.

  As a precondition of FIG. 2, first, at time T1 when the supply of the hydrothermal medium to the three indoor radiators 125a to 125c is stopped, the forward temperature Two is set to the target forward temperature Two (= 50 ° C.) and the return temperature Twit. Is a target return temperature Twit (for example, 35 ° C.).

  For this reason, when the user changes the number of indoor radiators 125 that supply the hydrothermal medium by operating the remote controller 124, the control unit 130 before time T1 moves to step S011 to control the rotation speed Fs. It has become.

  Moreover, it is assumed that the indoor radiators 125a to 125d are all the same. Assuming that the flow rate of the water heating medium delivered by the circulation pump 121 at time T1 is 6 L / min., Before the time T1, the flow rate of water heating medium supplied per indoor radiator is 6.0 L / min. /4=1.5L.

  Then, after time T1, the rotation speed Fs of the circulation pump 121 is controlled so that the circulation rate of the hydrothermal medium in the remaining indoor radiator 125d is maintained at 1.5 L / min.

  Further, the amount of heat (heat load) radiated by the four indoor radiators 125a to 125d is assumed to be the same before and after time T1. That is, the amount of heat (heat load) radiated in the indoor radiator 125d after time T1 is ¼ of the total amount of heat (heat load) radiated in the indoor radiators 125a to 125d before time T1. .

  When the supply of the hydrothermal medium to the three indoor radiators 125a to 125c is stopped at time T1, it is determined in step S009 that the number of indoor radiators that supply the hydrothermal medium has changed from 4 to 1. Next, in step S010, it is checked whether or not the difference between the going temperature Two and the target going temperature Two satisfies Equation 3.

(Equation 3) | Two-Twot | <ε1
Ε1 in Equation 3 is an allowable temperature error range, and this value is, for example, 0.3K.
The reason why the outgoing temperature Two is monitored in step S010 is to determine whether or not the room in which the indoor radiator 125 supplying the hydrothermal medium is sufficiently warmed.

If the determination in step S010 is not made, the indoor radiators 125a to 125c for stopping the supply of the hydrothermal medium are sufficiently warmed, but the hydrothermal medium is supplied even when only the indoor radiator 125d is not warmed. Since the number of indoor radiators to be reduced decreases, the flow rate of the hydrothermal medium is reduced in step S011 .

  When the flow rate of the water heating medium decreases, the going-out temperature temporarily increases and the frequency of the compressor decreases, or the increase in the frequency is delayed, so that a sufficient amount of heat may not be supplied to the unheated indoor radiator 125d. There is.

  If Equation 3 is not satisfied in step S010, the room where the indoor radiators 125a to 125d are radiating heat may not be sufficiently warmed. Therefore, the processing in steps S007 and S008, that is, the compressor 111 Control of frequency Fc is continued.

  Note that the determination in step S010 may be made based on whether or not the difference between the return temperature Twi and the target return temperature Twit satisfies Equation 4.

(Equation 4) | Twi-Twit | <ε2
Ε2 in Equation 4 is a return temperature error allowable range, and this value is, for example, 0.3K.
When the return temperature Twi has reached the target return temperature Twit (34 to 45 ° C.) over which the thermal sensation perceived by the thermoreceptor of the human skin is superior, the indoor radiator that supplies the hydrothermal medium It can be determined that the room in which 125 is installed is sufficiently warm.

  In the above example, since Equation 3 is satisfied at time T1, the process proceeds to step S011 so that the flow rate of the hydrothermal medium sent out by the circulation pump 121 is ¼ of 1.5 L / min. , The rotational speed Fs is controlled.

  Now, the flow rate of the water heat medium actually sent out by the circulation pump 121 needs to be measured by installing a flow rate sensor in the water heat medium cycle 120. However, if the relationship between the flow rate of the hydrothermal medium delivered by the circulation pump 121 and the head and the relationship between the flow rate of the hydrothermal medium flowing through the indoor radiators 125a to 125d and the pressure loss are clear, it can be estimated. It is.

  FIG. 3 shows the flow rate of the water heat medium sent from the circulation pump 121 on the horizontal axis, the pressure loss on the vertical axis, and the water heat medium when supplying the water heat medium to the four indoor radiators 125a to 125d. The relationship between the flow rate and the pressure loss is indicated by a line P4, and the relationship between the flow rate of the hydrothermal medium and the pressure loss when supplying the hydrothermal medium only to the indoor radiator 125d is indicated by a line P1.

  In FIG. 3, the line N indicates the relationship between the flow rate of the hydrothermal medium delivered by the circulation pump 121 and the pressure (head) when the rotation speed Fs of the circulation pump 121 is changed. This relationship is an upwardly convex curve, and the line N moves upward in FIG. 3 as the rotation speed Fs increases.

  When supplying a hydrothermal medium of 6 L / min to the four indoor radiators 125a to 125d, it is necessary to set the rotation speed Fs of the line N1 passing through the point A. At time T1, the supply of the water heat medium to the three indoor radiators 125a to 125c is stopped, and the flow rate of the water heat medium sent from the circulation pump 121 is set to 1 / minute of 1/4 in step S011 of FIG. In order to achieve 5 L / min, the rotation speed Fs of the line N2 passing through the point C is decreased.

In addition, when the rotation speed Fs of the circulation pump 121 is maintained in a state where the supply of the hydrothermal medium to the three indoor radiators 125a to 125c is stopped, the circulation amount of the hydrothermal medium in the indoor radiator 125d is The pressure does not become 6.0 L per minute which is four times higher, the state of the circulation pump 121 moves to the point B, the pressure loss of the hydrothermal medium increases, and the flow rate decreases.

  The time change of the going temperature Two and the return temperature Twi after the time T1 will be described with reference to FIG.

In step S011, even if the flow rate of the water heating medium sent from the circulation pump 121 is controlled to 1.5 L / min, which is 1/4, the circulation amount M _d of the water heating medium flowing through the indoor radiator 125d is substantially equal. It does not change. Therefore, based on the number 2, the temperature Twi _d hydrothermal medium flowing out of the indoor radiator 125d is hardly changed. That is, the return temperature Twi hardly changes.

On the other hand, the forward temperature Two of the water heat medium after being heated by the water heat medium heat exchanger 115 rapidly increases. This phenomenon is based on the number 1 relationship, for circulating amount M _E hydrothermal medium flowing Netsunakadachinetsu exchanger 115 becomes per minute 6.0 L 1.5 L and 1/4, the water heating medium heat if the amount of heat _{Q E} which in exchanger 115 to heat the water heat transfer medium is constant, becomes 4 times the temperature difference Two-Twi, and return temperature Twi is because hardly changed.

  In this state, the control unit 130 controls the frequency Fc of the compressor 111 in steps S007 and S008. Since the going temperature Two suddenly rises, the frequency Fc of the compressor 111 is suddenly lowered in order to return the going temperature Two to the target going temperature Two. As a result, the increase in the going temperature Two stops quickly and, on the contrary, turns down.

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 T2 in FIG. 2). The frequency Fc of the compressor 111, the time T1 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 a temporary sudden increase in the going temperature Two immediately after the time T1, and sometimes rises, but at the time T2, the return temperature difference Two-Twi is about the same as before the time T1. Calm down.

  That is, according to the present embodiment, even if there is a sudden drop in the heat load that stops the supply of the hydrothermal medium to some of the indoor radiators 125, the circulation amount of the hydrothermal medium is radiated indoors. Since the rotation speed Fs of the circulation pump 121 is controlled so as to be proportional to the number of the units 125, the increase of the return temperature Twi is reliably suppressed, the increase of the condensation temperature is prevented, and the efficiency of the heat pump cycle is reduced. In addition to preventing, the operating power of the circulation pump can be reduced.

  In addition, when the number of indoor radiators that supply the water heat medium is suddenly reduced, the circulation amount of the water heat medium is suddenly decreased, and the going temperature is rapidly increased. As a result, the frequency Fc of the compressor 111 is promptly lowered. The energy saving operation of the heat pump hot water heater 100 can be realized.

(Embodiment 2)
In this Embodiment, since the structure of the heat pump hot water heater 100 is the same as FIG. 4, description of the component is abbreviate | omitted. The flowchart describing the control operation of the control unit 130 for the compressor 111 and the circulation pump 121 is the same as that in FIG. 1, but the method for setting the flow rate of the hydrothermal medium is different in step S011.

In the first embodiment, the explanation has been made assuming that the indoor radiators 125a to 125d are all the same, but generally, the indoor radiators 125a to 125d have different areas and internal piping specifications, respectively. ing. Generally, the larger the amount of the water heat medium in the internal pipe of the indoor radiator, the larger the area and the greater the heat load. Therefore, in the present embodiment, the information on the amount of retained water is taken into account for the flow rate of the water heat medium set in step S011 of FIG.

  For example, in the indoor radiators 125a to 125d, when the holding amount of the hydrothermal medium is 2L, 3L, 3L, 3.5L, from the state where the hydrothermal medium is supplied to the indoor radiators 125a to 125d, After stopping the supply of the hydrothermal medium to the three indoor radiators 125a to 125c, the flow rate of the hydrothermal medium supplied to the remaining indoor radiator 125d is 6 L / min × 3.5 / (2 + 3 + 3 + 3.5) = 1.8L.

  As described above, when the water heat medium is supplied to the indoor radiator having a large area and a large amount of the water heat medium, the flow rate of the water heat medium can be set larger. On the contrary, when the area of the indoor radiator is small and the amount of the water heat medium is small, the flow rate of the water heat medium can be set low.

  Therefore, when the number of indoor radiators that supply the water heat medium decreases and the thermal load decreases sharply, the target flow rate of the water heat medium is set to the water heat medium of the indoor radiator. It can be set appropriately according to the amount held. Further, similarly to the first embodiment, the return temperature can be immediately suppressed from increasing, the condensation temperature can be prevented from increasing, the efficiency of the heat pump cycle can be prevented from being lowered, and the operating power of the circulation pump can be reduced.

(Embodiment 3)
FIG. 4 is a flowchart illustrating the control operation of the control unit 130 for the compressor 111 and the circulation pump 121 according to the third embodiment of the present invention.

  In addition, in this Embodiment, since the structure of the heat pump hot water heater 100 is the same as FIG. 4, description of the component is abbreviate | omitted. Hereinafter, steps S012 and S013, which are additional points from the flowchart of FIG. 1, will be described with respect to the operation when the number of indoor radiators 125 for supplying the water heat medium increases and the thermal load increases.

  When the start-up circulation flow rate control is finished after a predetermined time (for example, 10 minutes) has elapsed and the rotational speed Fs of the circulation pump 121 reaches the maximum rotational speed Fsmax, the control unit 130 can The change in the number of indoor radiators 125 that supply the medium is monitored (S009).

  When the user increases the number of indoor radiators 125 that supply the water heat medium with the remote controller 124, in step S012, it is determined whether the number of indoor radiators 125 that supply the water heat medium has decreased or increased. To do.

  When the number of indoor radiators 125 that supply the water heat medium decreases, it is determined in step S010 that the room in which the indoor radiator 125 is installed is sufficiently warmed, as in the first embodiment, and then step S011. And the rotational speed Fs of the circulation pump 121 is adjusted. Conversely, if the number of indoor radiators 125 that supply the water heat medium increases, the process proceeds to step S013, where the rotational speed Fs of the circulation pump 121 is set to the maximum rotational speed Fsmax.

  A case where the supply of the water heat medium to the three indoor heat radiators 125a to 125c is started at time T3 from the state where the water heat medium is supplied only to the indoor heat radiator 125d will be described.

  When the rotation speed Fs of the circulation pump 121 reaches the maximum rotation speed Fsmax in step S013, the circulation amount of the hydrothermal medium becomes maximum, and the temperature difference between the forward temperature Two and the return temperature Twi is based on the relational expression Get smaller.

For a while after the time T3, the unheated cold water heat medium staying in the internal pipes of the indoor radiators 125a to 125c flows into the water heat medium heat exchanger 115 through the buffer tank 122 all at once. The return temperature Twi is the lowest. Therefore, when the rotational speed Fs of the circulation pump 121 is set to the maximum rotational speed Fsmax, the going-out temperature Twot becomes the lowest.

  As a result, after satisfying Equation 3 in step S010 and shifting to the processing of step S007 and step S008, the temperature difference between the target forward temperature Twot and the forward temperature Two is large, so P control (proportional control) or PI control is performed. If this is used, the frequency Fc of the compressor 111 is promptly increased.

  That is, according to the present embodiment, even if the number of indoor radiators that supply the water heat medium increases and the heat load suddenly increases, the circulation rate of the water heat medium is maximized. Since the pump is controlled to reduce the going-out temperature to the maximum, it is possible to promptly increase the frequency of the compressor and to quickly warm the indoor radiator that has newly started supplying the water heating medium.

  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 change in the heat load, such as an increase or decrease in the number of indoor radiators that supply the water heat medium, the efficiency of the heat pump cycle can be prevented and the operating power of the circulation pump can be reduced. It can be applied to a heat pump hot water heater with 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 (6)

A heat pump cycle including a compressor, a heat medium heat exchanger that performs heat exchange between the refrigerant and the heat medium, an expansion valve, and a heat source side heat exchanger;
A plurality of indoor radiators for heating by the heat medium;
A circulation pump that circulates the heat medium between the heat medium heat exchanger and the plurality of indoor radiators, and a forward temperature that detects the temperature of the heat medium from the heat medium heat exchanger toward the indoor radiator. Detection means;
Return temperature detecting means for detecting the temperature of the heat medium returning from the indoor radiator to the heat medium heat exchanger;
And a heat medium supply control means for controlling the presence or absence of circulation of the heating medium between the heat medium heat exchanger and a plurality of the indoor radiator,
In the heat pump hot water heater that controls the operating frequency of the compressor so that the forward temperature detected by the forward temperature detection means becomes the target forward temperature,
When the number of the indoor radiators that circulate the heat medium with the heat medium heat exchanger decreases from N1 to N2 by the heat medium supply control means, the flow rate of the heat medium before the change is N2 / The heat pump hot water heater, wherein the circulation pump is controlled to have a flow rate multiplied by N1. A heat pump cycle including a compressor, a heat medium heat exchanger that performs heat exchange between the refrigerant and the heat medium, an expansion valve, and a heat source side heat exchanger;
A plurality of indoor radiators for heating by the heat medium;
A circulation pump that circulates the heat medium between the heat medium heat exchanger and the plurality of indoor radiators, and a forward temperature that detects the temperature of the heat medium from the heat medium heat exchanger toward the indoor radiator. Detection means;
Return temperature detecting means for detecting the temperature of the heat medium returning from the indoor radiator to the heat medium heat exchanger;
Heat medium supply control means for controlling the presence or absence of circulation of the heat medium between the heat medium heat exchanger and the plurality of indoor radiators ,
In the heat pump hot water heater that controls the operating frequency of the compressor so that the forward temperature detected by the forward temperature detection means becomes the target forward temperature,
The number of the indoor radiator that circulates the heating medium to and from the heating medium heat exchanger is changed by the heating medium supply control means, and is held in an internal pipe of the indoor radiator that circulates the heating medium. When the sum of the volumes of the heat medium decreases from L1 to L2, the heat pump is controlled so that the flow rate of the heat medium before the change is multiplied by L2 / L1. Hot water heater. When the number of the indoor radiators that circulate the heat medium with the heat medium heat exchanger is decreased by the heat medium supply control means, the difference between the forward temperature before the decrease and the target forward temperature is 3. The heat pump hot water heater according to claim 1, wherein the flow rate of the hydrothermal medium is reduced by a circulation pump when it is within an allowable temperature error range. When the number of the indoor radiators that circulate the heat medium with the heat medium heat exchanger decreases by the heat medium supply control means, when the return temperature before the decrease is equal to or higher than the target return temperature, The heat pump hot water heater according to claim 1 or 2, wherein the flow rate of the hydrothermal medium is lowered by a circulation pump. The heat pump hot water heater according to claim 4, wherein the target return temperature is selected from a first temperature range of 34 ° C. or higher and 45 ° C. or lower. When the number of the indoor radiators that circulate the heat medium with the heat medium heat exchanger is increased by the heat medium supply control means, the circulation is performed so that the flow rate of the heat medium becomes maximum. The heat pump hot water heater according to any one of claims 1 to 5, wherein the pump is controlled.