JPS63210554A - Heat pump water heater - Google Patents

Abstract

PURPOSE:To make it possible to rapidly heat hot water when it is in a low temperature state and to improve the high-temperature reaching ability for heating hot water up to a heating temperature (set temperature) by operating the hot water supplier while maintaining the maximum compression ability of a compressor until the hot water temperature reaches a reference temperature, and automatically lowering the compression ability when the hot water temperature exceeds the reference temperature. CONSTITUTION:The heat pump type hot water supplier has two operation control means 41 and 42. In a case where the hot water temperature in a hot water storage tank 28 is less than a reference temperature, that is, in a low-temperature state, the operation at the maximum heating ability such as controlling the compression ability along an input current defining line 12. Furthermore, when the hot water temperature within the hot water storage tank 28 approaches a heating target set temperature and exceeds the reference temperature, the operation of a compressor 1 is automatically switched to the control due to second operation control means 42. Upon this occasion, since the operation of the compressor 1 is carried out by changing a compression due to first operation control means 41, the rise in the discharge pressure up to that time is suppressed thereby.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a heat pump type water heater, and more particularly to a heat pump type water heater that has a compressor with variable compression capacity and has an overload operation prevention function. Regarding.

(Prior art) When hot water is heated with a heat pump type water heater, as the water temperature rises, the condensation temperature in the hot water heat exchanger also rises, and the condensation pressure, that is, the discharge pressure from the compressor, also rises. .

When the water temperature approaches the heating target setting temperature, which exceeds 60°C, for example, when the atmospheric temperature is also high on the heat source heat exchanger side that exchanges heat with the atmosphere, There may be an overload condition in which the discharge pressure reaches its service limit, increasing the risk of failure.

Therefore, in order to prevent the above-mentioned overload operation, the device described in JP-A-60-16245 is equipped with a discharge pressure detection sensor, and when the detected pressure reaches a predetermined value, the compressor is not operated. It is supposed to stop automatically.

However, in the conventional apparatus described above, although it is possible to prevent overload operation of the compressor, there is a problem in that the hot water in the hot water storage tank cannot be heated to the set temperature.

On the other hand, in recent years, heat pump water heaters having variable compression capacity compressors employing, for example, inverter control have also been put into practical use. In such a heat pump type water heater, in order to prevent overload operation of the compressor, the inverter frequency f and discharge pressure (IP) are used to vary the compression capacity.
For example, set the driving regulation lines 11 and 12 as shown in Fig. 5 while monitoring the
It is designed to operate within the range of l and β2. That is, in FIG. 5, one line 11 is a high pressure regulation line, which is set at a predetermined pressure (for example, 28 kg/cA) regardless of the inverter frequency, and is set so that the discharge pressure exceeds this during operation. If so, stop the compressor. The other line 12 is an input current regulation line to the compressor, and in relation to the inverter frequency f and discharge pressure + IP from the preset maximum allowable current, the higher the discharge pressure HP is, the higher the discharge pressure HP is as shown in the figure. It is set as a sloped straight line that keeps the inverter frequency f low.

When heating hot water in a hot water tank by operating the variable capacity compressor set in each of the regulation lines 11 and 12 as described above, if the water temperature is low, first The inverter frequency is started at an appropriate initial setting frequency at the start of operation (point A in the figure), and thereafter the inverter frequency is gradually increased in order to quickly heat the water to the set temperature. Control is performed to increase capacity. When the input current reaches the top of the input current regulation line 12 (point B in the figure), the maximum allowable current is input to the compressor, and the maximum compression capacity at this point, that is, the maximum in the hot water heat exchanger. Heating ability is provided. Due to such heating operation, the water temperature gradually rises, and therefore the discharge pressure +IP also increases, so after reaching the above-mentioned point B, the above-mentioned input current regulation line! Control is performed such that the inverter frequency f is decreased as the discharge pressure gauge increases while maintaining the maximum current flowing along line 2. Then, when the water temperature reaches the set temperature, the operation of the compressor is stopped.

(Problems to be solved by the invention) By controlling the inverter frequency as described above,
Since heating is continued while maintaining the maximum compression capacity at each point, it is possible to quickly heat up to the set temperature. However, the set temperature is 60-65°C
If the atmospheric temperature is high and the atmospheric temperature at the heat source side heat exchanger due to heat exchange with the atmosphere is also high, when performing inverter frequency control along the input current regulation line 22 as described above, the above set temperature There is a problem in that the high pressure regulation line 11 is reached before the temperature reaches the set temperature, and as a result, the operation of the compressor is automatically stopped and heating cannot be performed up to the set temperature.

This invention was made in order to solve the above-mentioned conventional problems, and its purpose is to achieve rapid heating when the water temperature is low, and to increase the boiling temperature (set temperature).
To provide a heat pump water heater capable of improving the ability of a tank to reach a high temperature.

(Means for Solving the Problems) Therefore, the heat pump water heater of the present invention includes a compressor 1 with variable compression capacity, a heat source side heat exchanger 1o, and a hot water supply heat exchanger for heating hot water in a hot water storage tank 28. This is a heat pump type water heater which is connected to a water heater 23, as shown in FIG.
Hot water temperature detection means 38 for detecting the hot water temperature in the hot water storage tank 28;
When the detected hot water temperature is equal to or lower than a reference temperature set lower than the second heating target set temperature, the operation of the compressor 1 is controlled with a compression capacity that provides a predetermined heating capacity to the hot water supply heat exchanger 23. a first operation control means 41; and when the detected hot water temperature exceeds the reference temperature, the first operation control means 4
The second operation control means 42 controls the operation of the compressor 1 by changing the compression capacity to a smaller compression capacity than the compression capacity controlled by the compressor 1.

(Function) The heat pump type water heater having the above configuration has two operation control means 41 and 42, and when the hot water temperature in the hot water storage tank 28 is below the reference temperature, that is, in a low temperature state,
The first operation control means 41 performs operation at the maximum heating capacity, such as controlling the compression capacity along the input current regulation line 12, for example, so that the hot water temperature can be quickly raised. In addition, when the hot water temperature in the hot water storage tank 28 approaches the heating target set temperature and exceeds the reference temperature, the operation of the compressor 1 is controlled by the second operation control means 42.
control is automatically switched to

At this time, the compressor 1 is operated with the compression capacity changed to a smaller one than the compression capacity by the first operation control means 41, so that the increase in the discharge pressure up to that point is suppressed, and therefore, for example, the above-mentioned high pressure pressure regulation line j
The frequency of operation stoppage due to reaching 21° is reduced, and heating operation can be continued more than before. As a result, the high temperature reached is increased, and the heating capacity is improved.

(Example) Next, a specific example of the heat pump water heater of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows a refrigerant circuit diagram of an apparatus configured as a heat pump system having a heat pump hot water supply function and a multi-room air conditioning function according to an embodiment of the present invention. outdoor unit X,
It has indoor units) A-D and a hot water supply unit 9. The outdoor unit X has a compressor 1, and a discharge pipe 2 and a suction pipe 3 of the compressor 1 are each connected to a four-way switching valve 4. The compressor 1 has an inverter 5 for controlling its rotational speed, that is, its compression capacity, and the discharge pipe 2 has a first solenoid valve 6, and the suction pipe 3 has an accumulator 7. Intervention is provided. A first gas pipe 8 is connected to the four-way switching valve 4.
The first gas pipe 8 is connected to an outdoor heat exchanger 10 serving as a heat exchanger on the heat source side, and the second gas pipe 9 is connected to a header 11. At the same time, a gas shutoff valve 12 is interposed in the middle. Further, a first liquid pipe I3 is connected to the outdoor heat exchanger 10, and this first liquid pipe 13 is connected to a liquid receiver 14, and a first expansion valve 15 is interposed in the middle thereof. has been done.

A second liquid pipe 16 is connected to the liquid receiver 14, and this second liquid pipe 16 has a liquid shutoff valve 17 interposed in the middle, and is connected to the second gas pipe 9. Between the second liquid pipe 16 and the second liquid pipe 16, there are a plurality of branch refrigerant pipes 18 (four in the case of the figure).
・18 are connected in parallel to each other, and each branch refrigerant pipe 18...18 is connected to an indoor heat exchanger 19...19(
(only one is shown) and second expansion valves 20...20 are interposed. Although only one indoor unit A is shown in the figure, each of the indoor units A to D is composed of the indoor heat exchangers 19...19 and the indoor fans 21...21.

On the other hand, a third gas pipe 22 is further connected to the discharge pipe 2 of the compressor 1, and a hot water supply heat exchanger 23 is connected to the third gas pipe 22.
is further connected to the liquid receiver 14 through a third liquid pipe 24 . A second electromagnetic valve 25 is provided in the third gas pipe 22, and a capillary tube 26 and a check valve 27 are provided in the third liquid pipe 24. Note 28
is a hot water tank. Further, a high pressure switch 29 is connected to the discharge pipe 2, which is activated when the discharge pressure exceeds a set pressure (for example, 28 kg/cdl).

During cooling operation of the above device, the compressor 1 is operated with the first solenoid valve 6 opened and the second solenoid valve 25 closed.

Then, the refrigerant passes through the four-way switching valve 4 and the first gas pipe 8, condenses in the outdoor heat exchanger lo, and then the first liquid pipe 13.
, evaporates in each indoor heat exchanger 19 . It becomes a flowing stream. In this case, the first expansion valve 15 is fully opened, and each second expansion valve 2
The degree of superheating of the evaporative refrigerant is controlled at 0...20. The heating operation is performed by switching the four-way switching valve 4 from the cooling operation state and circulating the refrigerant discharged from the compressor 1 from the indoor heat exchangers 19 to the outdoor heat exchanger 10. In this case, each second expansion valve 20...20 controls the amount of refrigerant flowing through each indoor heat exchanger 19...19, and the first
The expansion valve 15 controls the degree of superheating of the evaporative refrigerant.

Also, during hot water supply operation, the first solenoid valve 6 is closed and the second solenoid valve 2 is closed.
5 is opened and the compressor 1 is operated. Then, the refrigerant passes through the third gas pipe 22, condenses in the hot water supply heat exchanger 23, and then passes through the third liquid pipe 24, the liquid receiver 14, and the first liquid pipe 1.
3, evaporates in the outdoor heat exchanger 10, and then returns to the compressor 1 via the first gas pipe 8 and the four-way switching valve 4. In this case, each of the second expansion valves 20 . . . 20 is fully closed, and the first expansion valve 15 controls the degree of superheating of the evaporative refrigerant.

Next, we will discuss the operation control system during hot water supply operation of the above device in the third section.
This will be explained based on the diagram. First, the outdoor unit X has an outdoor control device 31, an inverter control device 32, and a valve switching means 33. This is to control the rotational speed of the engine, that is, the compression capacity. Further, the valve switching means 33 controls the operations of the first solenoid valve 6, the second solenoid valve 25, and the four-way switching valve 4 in response to a command from the outdoor control device 31, so as to perform hot water supply operation, heating operation, This is for controlling operation modes such as cooling operation.

Further, a remote control box 36 placed in a room such as a kitchen is connected to the outdoor control device 31, and by operating a hot water tank heating switch 37 provided in this box 36, the outdoor control device 31 It is possible to output a heating request signal. In this case, in order to detect the hot water temperature, a hot water temperature thermometer 39 having a hot water temperature detection sensor 38 which is a hot water temperature detecting means constituted by a thermistor is arranged in the hot water storage tank 28, and the hot water storage tank heating switch 37 is disposed in the hot water storage tank 28. is ON, if the temperature detected by the thermistor 38 is lower than the set temperature set in the hot water temperature thermometer 39, the hot water temperature thermometer 39 sends a heating operation request to the outdoor control device 31. The signal and the detected temperature signal are output.

On the other hand, the outdoor control device 31 further receives an activation signal of the high pressure switch 29 and a detected current signal from a current transformer 40 provided for detecting the input current value to the compressor 1. Along with this,
In order to perform hot water heating operation while controlling the rotation speed of the compressor 1, that is, the inverter frequency, in response to the heating operation request signal and the detected temperature signal, first and second operation control means are used. 1 and 2nd frequency control section 41.42
Next, impark frequency control during hot water supply heating operation will be explained based on the flowchart of FIG. 4.

When the hot water storage tank heating switch 37 is turned on and hot water heating operation is started, first, in step S1 of FIG. 4, it is determined whether the hot water temperature thermostat 39 is in the ON-OFF state. When the hot water in the hot water storage tank 28 is currently in a low temperature state, the above O
Explaining that the N operation has been performed, the detected hot water temperature T is lower than the heating target set temperature Tm (for example, 65°C), and the hot water temperature thermometer 39 outputs a heating operation request signal, that is, the outdoor control device 31 In the case, hot water temperature thermometer 39
is determined to be in the ON state, and the process moves from step S1 to step S32. Then, in step S2, the initial setting frequency fO is set for the compressor 1, which had been stopped up to that point, and is started. Next, in step S3, the high pressure switch 29 connected to the discharge pipe 2 changes the discharge pressure HP to an abnormally high pressure setting value Pma.
% or less, and in step S4, it is determined whether the operating frequency of the compressor after startup has reached the initial setting frequency fO.

If it has not been reached, the process returns from step S4 to step SL, and steps 81 to S4 are repeated to wait for the compressor 1 to start up. When the compressor 1 reaches the initial setting frequency, the process moves from step S4 to step S5. In this step S5, it is determined whether the detected hot water temperature in the hot water storage tank 28 has reached the reference temperature Tc (for example, 55° C.). If the temperature T of the hot water heated from a low temperature state is equal to or lower than the above Tc, the process moves from step S5 to step S36. In this step S6, the input current value i to the compressor 1 detected by the current transformer 40 is compared with the first maximum allowable current value imaxl. If the above i is smaller than imaxl, step S7
The inverter control frequency f is increased in step S8, while if i is greater than imaxl, f is decreased in step S8 and the process returns to step S1. Then, the above steps 31 to S8 are repeated to continue supplying and heating the hot water.

Changes in the inverter frequency f, discharge pressure HP, and heated water temperature T during the heating operation as described above will be explained with reference to FIG. 5. FIG. 5 shows the abnormal high pressure setting value Pma in relation to the inverter frequency f and the discharge pressure BP.
It shows an operating range defined by a high-pressure regulation line 11 based on The relationship between the hot water temperature obtained when the atmospheric temperature is set to, for example, 30°C and the above operating conditions is appended. As shown in the figure, the heating operation is started with the initial setting frequency fO set to, for example, 50 Hz (point A in the figure). If the water temperature at this time is approximately 25°C and the heating target temperature Tm is 65°C, at the above point A, the input current regulation line! Since there is a sufficient margin between point A and point B, by performing the frequency control described above, operation is continued in which the change from point A toward point B, that is, the frequency is successively increased.

During this time, the temperature of the hot water rises and the discharge pressure also rises. Then, at point B, that is, when the input current to the compressor 1 reaches the maximum allowable current value imaxl, frequency control is thereafter performed so as to maintain this current value. In other words, since the discharge pressure increases as the water temperature increases, the above i
In order to maintain the input current state of maxl, it is necessary to reduce the frequency, and as a result, the input current regulation line in the same figure! Frequency control is performed according to 2. During this time, imaxl is approximately maintained, and therefore the hot water is heated at the maximum possible compression capacity, that is, heating capacity, of this device. In the figure, when the point B reaches point 0 and this control is continued, the high pressure regulation line 11 will be reached at the point in the figure, that is, when the water temperature reaches 60°C. , the high pressure switch 29 is activated, the abnormal high pressure state is determined, and the operation is stopped.

As a result, heating up to the heating target set temperature of 65°C cannot be performed.

Therefore, in the above device, the frequency control is automatically switched when the water temperature reaches, for example, 55°C. That is, in FIG. 4, step S5
, the detected hot water temperature T is the reference temperature Tc (for example, 55°C)
When the value exceeds this value, the process moves from step S5 to step S9. In step S9, the input current value i
is compared with the second allowable current value imax2, and according to the result, the frequency is increased (step S7), N (step S
8).

The second allowable current value imax2 is smaller than the first allowable current value imaxl. Therefore, in Figure 5, after the 0 point when the water temperature reaches the above Tc,
The frequency control is changed to step S9 described above, and as a result, the frequency is reduced from point C to point F in the figure, and the input terminal is changed from the imaxl state to the smaller imax2.

In other words, the compression capacity is reduced. And imax2
After reaching , the second
Control is performed along the input current regulation line i3, and F in the figure
It will lead from point to point G. Then, at point G, the target heated water temperature, for example 65°C, is reached and the hot water temperature thermometer 39 is turned OFF.
Changes to the FF state, moves from step S1 to step SIO in FIG. 4, stops the compressor 1, and repeats steps S1 and SIO while inputting the next heating operation request signal from the hot water temperature thermometer 39. It will be in a waiting state.

By performing the frequency control as described above, the heating is not interrupted because the discharge pressure + IP reaches Pmax in step S3 in FIG. 4 and the operation is stopped in step Sll, and the set boiling point is It is ensured that the temperature is reached.

As described above, in the above embodiment, the maximum compression capacity is maintained while making changes according to each discharge pressure state until the reference temperature Tc is reached, and a rapid rise in the hot water temperature is obtained. After the above Tc is exceeded, the boiling temperature is ensured by automatically reducing the compression capacity.

In the above embodiment, an example was shown in which the first operation control means 41 was constituted by steps S6, S7, and S8 in FIG. 4, and the second operation control means 42 was constituted by steps S9, S7, and S8. The second operation control means is controlled so that the water temperature is at a predetermined temperature T.
When reaching c, the lowest frequency that can be operated, for example 4
Other configurations are also possible, such as lowering the frequency to 0 Hz and maintaining it there. Further, in the above, the hot water temperature detecting means is the hot water temperature detecting sensor 38 constituting the hot water temperature thermometer 39, but a thermistor attached to the outlet side piping of the hot water supply heat exchanger 23 to detect the condensing temperature, It can also be configured with other sensors that can output signals correlated with the water temperature, such as a pressure sensor that detects pressure changes.

Furthermore, although the configuration in which frequency control is performed by the inverter control device 32 when controlling the compression capacity of the compressor 1 has been described above, this can also be implemented by other methods.

(Effects of the Invention) As described above, in the heat pump type water heater of the present invention, the compressor operates while maintaining the maximum compression capacity until the water temperature reaches the reference temperature, so that the water temperature quickly rises. In addition to this, when the above reference temperature is exceeded, the compression capacity is automatically reduced to continue heating while suppressing the increase in discharge pressure, so the temperature reached is higher than before and the heating capacity is increased. improves.

[Brief explanation of the drawing]

The figures show an embodiment of the heat pump type water heater of the present invention. Figure 1 is a functional diagram, and Figure 2 is a diagram of a device to which the present invention is applied and configured as a multi-system that also has a multi-room air conditioning function. Refrigerant circuit diagram, Figure 3 is a block diagram of the operation control system, Figure 4 is a flowchart of the hot water heating operation control method, and Figure 5 explains the operating range in relation to the compressor inverter control frequency and discharge pressure. It is a diagram. DESCRIPTION OF SYMBOLS 1... Compressor, 10... Outdoor heat exchanger (heat source side heat exchanger), 23... Hot water supply heat exchanger, 28... Hot water storage tank, 38... Hot water temperature detection sensor (hot water temperature detection sensor) temperature detection means), 41.
...first frequency control section (first operation control means), 42...
- Second frequency control section (second operation control means).

Claims (1)

[Claims] 1. A compressor with variable compression capacity (1) and a heat source side heat exchanger (1)
0) and a hot water supply heat exchanger (23) for heating hot water in a hot water storage tank (28), the heat pump type water heater is configured to detect the temperature of hot water in the hot water storage tank (28). a hot water temperature detection means (38); and a compression capacity that provides a predetermined heating capacity to the hot water supply heat exchanger (23) when the detected hot water temperature is below a reference temperature that is set lower than the heating target temperature. and a first operation control means (41) that controls the operation of the compressor (1) when the detected hot water temperature exceeds the reference temperature. A heat pump type water heater characterized in that it has a second operation control means (42) that controls the operation of the compressor (1) by changing the compression capacity to a smaller compression capacity.