Water heater

Abstract

To provide a water heater which can determine whether a water flow into a circulation pump is in a full state, gas-liquid mixed state, or a water shortage state using a predefined determination value with motor consumption power and motor rotation speed as parameters.SOLUTION: A water heater (1) includes: a circulation passage (28); a heating part (16); a circulation pump (27); and control means (20) for controlling the heating part (16) and a motor for driving the circulation pump. The circulation pump (27) includes: motor rotation speed detection means; motor consumption power detection means; and determination means for determining the state of hot water flow using the determination value calculated by the motor rotation speed and the consumption power. When the determination means determines that the hot water flow is abnormal, the determination value is corrected. When it is determined that there is a hot water flow with the corrected determination value, it is determined that the hot water circulates in a gas-liquid mixed state in which gas bubble is contained and an operation of the circulation pump continues. When it is determined that the hot water is not in the gas-liquid mixed state with the corrected determination value, it is determined that the heater is in a water shortage state and an operation of the circulation pump stops.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a hot water device, and more particularly to a hot water device capable of detecting the water flow state in a circulation passage provided with a circulation pump without using a water flow sensor, a flow meter, or the like.

Background Art

[0002] Various techniques have been proposed for detecting the water flow state in a circulation passage provided with a circulation pump without using a water flow sensor, a flow meter, or the like. For example, in the circulation pump described in Patent Document 1, a determination value is calculated from a predetermined arithmetic expression using a command voltage for driving the pump, a pump rotation speed, power consumption, and a drive voltage of a motor for driving the pump, At least one of the command voltage, the pump rotation speed, the power consumption, and the determination value is used as a comparison target, When the value used as the comparison target is outside a predetermined range set in advance, it is determined that the water flow in the circulation passage is abnormal.

[0003] In the determination circuit described in Patent Document 2, there is a determination means for determining that the water flow in the circulation passage is abnormal when the power consumption of the pump drive motor detected by the motor power consumption detection means is outside a predetermined range set in advance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The water flow state determination technique of the above-mentioned Patent Documents 1 and 2 is applicable only when the circulation passage is in a full-water state during operation. In the gas-liquid mixed flow during the self-priming operation after pouring hot water into the bathtub, even when the circulation is carried out at a flow rate at which it should be determined that there is a flow of hot water during full-water circulation, there is a problem that it may be erroneously determined that there is no flow of hot water.

[0006] An object of the present invention is to provide a hot water device capable of determining whether the water flow to the circulation pump is in a full-water state, a gas-liquid mixed state, or a waterless state by using a predetermined determination value with the power consumption of the motor and the rotational speed of the motor as parameters.

Means for Solving the Problems

[0007] The hot water device according to claim 1 includes a circulation passage, a heating unit for heating the hot water flowing through this circulation passage, a circulation pump for circulating the hot water, a control means for controlling the heating unit and the circulation pump, the circulation pump includes an impeller, a motor to which a drive voltage is input from the control means to rotationally drive the impeller, a rotational speed detection means for detecting the rotational speed of the motor, and a motor power consumption detection means for detecting the power consumption of the motor. In the hot water device having a determination means for determining the state of the hot water flow using a determination value calculated from the rotational speed and power consumption of the motor detected by these detection means, when the control means determines that the hot water flow is abnormal by the determination means, it corrects the calculated determination value. When it is determined that there is a hot water flow with this corrected determination value, it is determined that the hot water is being circulated in a gas-liquid mixed state with bubbles mixed in, and the operation of the circulation pump is continued. When it is determined that it is not in the gas-liquid mixed state with the corrected determination value, it is determined that it is in a waterless state, and the operation of the circulation pump is stopped.

[0008] According to the above configuration, when the control means determines that the flow of hot and cold water is abnormal by the determination means, it corrects the calculated determination value, and determines the state of the flow of hot and cold water with this corrected determination value, thereby determining whether it is a gas-liquid mixed state or a dry water state. When it is in the gas-liquid mixed state, the operation of the circulation pump is continued, and when it is determined to be in the dry water state, the operation of the circulation pump is stopped. Therefore, it is possible to accurately determine the state of the flow of hot and cold water and perform pump control according to the state of the flow.

[0009] The hot water device according to claim 2 is characterized in that, in the invention of claim 1, when it is determined to be in a gas-liquid mixed state, a gas-liquid mixing ratio calculating means for calculating a gas-liquid mixing ratio using a pump rotation speed or a pump command voltage is provided. According to the above configuration, since the gas-liquid mixing ratio calculating means for calculating the gas-liquid mixing ratio using the pump rotation speed or the pump command voltage is provided when it is determined to be in the gas-liquid mixed state, it is possible to use the gas-liquid mixing ratio in the correction formula for correcting the determination value.

Effects of the Invention

[0010] The present invention has various actions and effects as described above.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments for carrying out the present invention will be described based on examples.

Example

[0013] First, the configuration of the bathtub water heater 1, which is a hot water device, will be described based on FIG. 1. The bathtub water heater 1 includes a combustion type water heater that heats the city water supplied as shown by arrow W with the combustion heat of fuel gas and supplies the hot water adjusted to a predetermined temperature to the outside as shown by arrow HW. However, it may have other heat source machines such as a heat pump type heat source machine. This bathtub water heater 1 performs a hot water supply operation of supplying hot water at a preset hot water supply set temperature. Further, the bathtub water heater 1 performs hot water filling by pouring hot water at a preset bathtub set temperature into the bathtub 3 up to a preset set water level, and performs a reheating operation of heating the hot water in the bathtub 3 to the bathtub set temperature and returning it to the bathtub 3.

[0014] The bathtub water heater 1 has a fuel gas supply unit 11, a blower fan 12 that supplies combustion air, a water heating burner 13 and a bathtub burner 14 that burn fuel gas, and a water heating heat exchanger 15 that uses the heat of the high-temperature combustion gas generated by combustion to heat the city water and a bathtub heat exchanger 16 that heats the hot water in the bathtub 3. A water supply flow rate sensor 18 that detects the flow rate of the city water is disposed in a water supply passage 17 that supplies the city water to the water heating heat exchanger 15. A distribution valve 19 whose distribution ratio can be adjusted is disposed upstream of the water supply flow rate sensor 18.

[0015] In order to control various operations by controlling the distribution ratio of the distribution valve 19 based on the detected flow rate of the water supply flow rate sensor 18 and the combustion control of the water heating burner 13, etc., a control unit 20 is provided in the bathtub water heater 1. Further, in order to neutralize and discharge the acidic condensed water in which the moisture in the combustion gas has condensed in the water heating heat exchanger 15 and the bathtub heat exchanger 16, a neutralizer 21 containing a neutralizing agent is equipped.

[0016] When the water supply flow rate sensor 18 detects a flow rate equal to or higher than a preset minimum operating flow rate, the control unit 20 causes the water heating burner 13 to burn and heats the make-up water with the water heating heat exchanger 15. The heated hot water is supplied to the hot water outlet passage 22, and at the distribution valve 19, it is mixed with the make-up water from the make-up water bypass passage 23 that branches off from the make-up water passage 17 and is connected to the hot water outlet passage 22, and the temperature is adjusted.

[0017] When the destination of the hot water is, for example, a hot water tap (not shown), hot water adjusted to the set hot water supply temperature is supplied. When the destination of the hot water is the bathtub 3, hot water adjusted to the bathtub set temperature is poured through the pouring passage 25 provided with the pouring valve 24. The pouring flow rate into the bathtub 3 is detected by a pouring flow rate sensor 26 disposed upstream of the pouring valve 24. The control unit 20 calculates the amount of poured hot water into the bathtub 3 based on this pouring flow rate and the pouring time.

[0018] A post-combustion passage 28 equipped with a bath pump 27 (circulation pump) is connected to the bath heat exchanger 16 to circulate the hot water in the bathtub 3. The control unit 20 drives the bath pump 27 and causes the burner 14 to burn to control a post-combustion operation in which the hot water in the bathtub 3 flowing through the post-combustion passage 28 (circulation passage) is heated by the bath heat exchanger 16 and returned to the bathtub 3.

[0019] The pouring passage 25 is connected to the post-combustion passage 28 via the bath pump 27. When pouring, the pouring valve 24 is opened, and for example, hot water adjusted to the bathtub set temperature is poured from the pouring passage 25 into the bathtub 3 through the post-combustion passage 28.

[0020] A water level sensor 29 that detects the water level of the bathtub 3 by water pressure is disposed in the pouring passage 25. The control unit 20 detects bathing and leaving the bath based on the change in the water level of the bathtub 3. A bath temperature sensor 30 that detects the hot water temperature of the bathtub 3 is disposed downstream of the bath pump 27 in the post-combustion passage 28. The hot water temperature of the bathtub 3 is detected with the bath pump 27 driven and the hot water in the bathtub 3 flowing through the post-combustion passage 28. Incidentally, the water level sensor 29 may be disposed in the post-combustion passage 28.

[0021] The bathtub hot water supply device 1 has an operation terminal for performing various setting operations such as the start operation of the reheating operation, the hot water supply set temperature, the bathtub set temperature, and the set water level. As this operation terminal, for example, a bathroom remote control 4 installed in the bathroom and a kitchen remote control 5 installed in the kitchen, for example, are communicatively connected to the control unit 20. The bathroom remote control 4 and the kitchen remote control 5 are equipped with display units 4a and 5a for displaying setting information and the like, and voice output units 4b and 5b in addition to a plurality of operation buttons. Further, the bathroom remote control 4 is equipped with a human sensor 4c for detecting a user in the bathroom.

[0022] Next, the water flow state determination control for determining whether or not there is a flow of hot water (water flow) in the circulation pump 27 will be described with reference to FIGS. 2 and 3. FIG. 2 shows a configuration diagram of a control system for the circulation pump 27. The circulation pump 27 includes a DC brushless motor 35, an impeller 36 driven by this motor 35 to pressurize hot water, a control circuit 37 including a drive circuit and an inverter circuit, and a determination circuit 38 having a means for determining the state of the water flow in the circulation passage 28. Note that the control circuit 37 and the determination circuit 38 are stored in the circulation pump 27.

[0023] The control unit 20, the control circuit 37, and the determination circuit 38 correspond to "control means". A command voltage Vsp, a motor drive voltage Vm, and a power supply voltage Vcc are supplied from the control unit 20 to the control circuit 37. The motor speed control is performed by the control circuit 37 in a PWM manner. The voltages input to the control circuit 37 are the power supply voltage Vcc, the command voltage Vsp, and the motor drive voltage Vm, and these are supplied from the control unit 20.

[0024] A motor rotation speed signal composed of a pulse signal output from a hall element is supplied from the circulation pump 27 to the control unit 20 and the determination circuit 38, and a drive current I for driving the motor 35 is supplied from the control circuit 37 to the determination circuit 38. Note that various information can be transmitted from the determination circuit 38 to the control unit 20 via the signal line 39.

[0025] The determination circuit 38 includes an input / output interface, a microcomputer (including a CPU, ROM, and RAM), a command voltage detection means, a rotation speed detection means, a motor power consumption detection means, and a determination means. Note that the water flow state determination control shown in FIG. 3 corresponds to the determination means. The command voltage detection means, the rotation speed detection means, the motor power consumption detection means, and the determination means are configured by a control program pre-stored in the microcomputer.

[0026] Next, the flowchart of the water flow state determination control shown in FIG. 3 will be described. In the figure, Si (i = 1, 2,...) indicates each step. In S1, it is determined whether the operation mode of the pump 27 is a constant rotation speed operation. The normal operation of the pump is performed at a constant rotation speed, and the self-priming operation after pouring hot water into the bathtub is performed at a constant command voltage. If the determination in S1 is yes, the constant rotation speed operation is continued in S2, and in the next S3, the command voltage Vsp to the pump drive motor 35 is detected.

[0027] Next, in S4, a determination value D for determining the state of the water flow is calculated as follows. D = W × 10 5 / (0.163 × N 2 ) + (5.79 - W 0.5 ) × 14.2 ··· (1) The above W is the power consumption of the pump drive motor 35, and N is the rotation speed of the pump 27.

[0028] If the determination in S1 is No, the process proceeds to S5 where the constant command voltage operation is continued. In the next S6, the rotation speed N of the pump 27 is detected, and then in S7, the determination value D is calculated by the above arithmetic expression (1).

[0029] In S8 following S4 or S7, it is determined whether the determination value D is greater than or equal to a threshold value (for example, 156). If the determination is Yes, it is determined as a full water state in S9, and then the process returns. On the other hand, if the determination in S8 is No, the process proceeds to S10 where a water flow abnormality is determined. Next, in S11, a correction value E of the determination value D is calculated by the following formula. Correction value E = 0.42 × determination value D + 103.833 ··· (2)

[0030] Next, in S12, it is determined whether the corrected determination value E is greater than or equal to a threshold value (for example, 155.5). When the determination is Yes, it is determined that the gas-liquid mixed state is in S13. In the next S14, the operation of the pump 27 is continued, and then it returns. When the determination in S12 is No, it is determined that the water shortage state is in S15, the operation of the pump 27 is stopped, and then this control is stopped.

[0031] Next, in the bath water supply device 1, a time chart (actual machine verification result) of the flow rate, rotation speed N, determination value D, corrected determination value E, threshold value, etc. for the circulation pump 27 when starting the self-priming operation after pouring hot water into the bath with a fixed command voltage operation is shown in FIG. 4. The horizontal axis represents time (seconds). As indicated by reference sign B, since the rotation speed N rises sharply, as indicated by reference sign A, the flow rate decreases significantly and a gas-liquid mixed state is formed. At this time, as indicated by reference sign C, the determination value D becomes smaller and is smaller than the threshold value. At this time, by correcting the determination value D, when the swing range downward of the corrected determination value E is reduced, the corrected determination value E becomes a value larger than the threshold value.

[0032] Next, a gas-liquid mixing ratio calculating means for calculating the gas-liquid mixing ratio using the pump rotation speed or the pump command voltage when it is determined that the gas-liquid mixed state is formed will be described. The control program (not shown) as this gas-liquid mixing ratio calculating means is stored in the control unit 20 in advance. As shown in FIG. 5, when in the full water state, the operation command voltage Vsp 0、 From the state of operating at the rotation speed N0, passing through the gas-liquid mixed state and becoming the water shortage state, the operation command voltage Vsp 1、 Taking the case of operating at the rotation speed N1 as an example, a method for calculating the gas-liquid mixing ratio α will be described.

[0033] When it is in the gas-liquid mixed state, if the operation command voltage Vsp 、 at this time is the rotation speed N, it is considered that the gas-liquid mixing ratio α can be calculated by the following arithmetic expression. α = (N - N0) / (N1 - N0) = (Vsp - Vsp0) / (Vsp1 - Vsp0) Using the gas-liquid mixing ratio α calculated as described above, it is also possible to correct the correction determination value Em as follows, for example.

[0034] Correction value Em = 0.42 × determination value D + 103.833 × (1 - α 2 ) ···· (3) When correcting in this way, as the gas-liquid mixing ratio α increases, the value of (1 - α 2 ) becomes smaller, and the correction value Em becomes smaller. Therefore, the probability of being determined as No in the determination of S16 in FIG. 3 increases.

[0035] Next, the actions and effects of the water flow state determination control described above will be described. When the control means (20, 37, 38) determines that the flow of hot and cold water is abnormal by the determination means, it corrects the calculated determination value D, and determines the state of the flow of hot and cold water with this corrected determination value E, thereby determining whether it is a gas-liquid mixing state or a dry water state. When it is in the gas-liquid mixing state, the operation of the circulation pump 27 is continued, and when it is determined to be in the dry water state, the operation of the circulation pump 27 is stopped. Therefore, it is possible to accurately determine the state of the flow of hot and cold water and perform pump control according to the state of the flow.

[0036] Since the gas-liquid mixing ratio calculating means for calculating the gas-liquid mixing ratio using the pump rotation speed or the pump command voltage is provided when it is determined to be in the gas-liquid mixing state, it is possible to use the gas-liquid mixing ratio in the correction formula for correcting the determination value D, and the determination accuracy of the determination value D can be improved.

[0037] In addition, although the above-described embodiment has been described by taking the case where the present invention is applied to the bath water supply device 1 as an example, it is not limited thereto, and the present invention can be similarly applied to other forms of hot water devices provided with a circulation passage, a heating unit, a circulation pump, a control means, and the like. Also, those skilled in the art can implement the present invention in a form in which various changes are added to each part of the flowchart of the water flow state determination control of the present invention.

Description of Symbols

[0038] 1 Bathtub water supply device 16 Bathtub heat exchanger 20 Control unit 27 Circulation pump 35 Motor 36 Impeller 37 Control circuit 38 Judgment circuit D Judgment value E Correction judgment value α Gas-liquid mixing ratio

Claims

1. A hot water device having a circulation passage, a heating unit for heating the hot and cold water flowing through this circulation passage, a circulation pump for circulating the hot and cold water, control means for controlling the heating unit and the circulation pump, wherein the circulation pump includes an impeller, a motor to which a drive voltage is input from the control means to rotationally drive the impeller, a rotational speed detection means for detecting the rotational speed of the motor, and a motor power consumption detection means for detecting the power consumption of the motor, and having determination means for determining the state of the flow of the hot and cold water using a determination value calculated from the rotational speed and power consumption of the motor detected by these detection means, when the control means determines that the flow of the hot and cold water is abnormal by the determination means, the calculated determination value is corrected, and when it is determined that there is a flow of the hot and cold water with the corrected determination value, it is determined that the hot and cold water is circulating in a gas-liquid mixed state with air bubbles mixed in, and the operation of the circulation pump is continued, and when it is determined that it is not in the gas-liquid mixed state with the corrected determination value, it is determined that it is in a water shortage state and the operation of the circulation pump is stopped. A hot water device characterized by this.

2. The hot water device according to claim 1, further comprising gas-liquid mixing ratio calculation means for calculating a gas-liquid mixing ratio using the pump rotational speed or the pump command voltage when it is determined that the state is a gas-liquid mixed state.

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