Water heater

Abstract

To provide a water heater having a failure determination means for performing a failure determination before combustion operation when installing a circulation pump with a built-in water flow determination circuit which can determine presence / absence of water flow in the circulation passage.SOLUTION: A bath water heater includes: a heating part for heating water flowing in a circulation passage; a circulation pump for circulating the hot water; and control means for controlling the heating part and the circulation pump. The circulation pump includes: an impeller; a motor for rotationally driving the impeller by a driving voltage input from the control means; rotation detection means for detecting the motor rotation speed; and motor consumption power detection means for detecting the consumption power of the motor. The bath water heater includes determination means for determining presence / absence of a hot water flow using the determination value calculated by the motor rotation speed and the consumption power. When an operation of the circulation pump includes a heating operation by the heating part, the failure determination means determines the failure of the determination means. When an operation of the circulation pump does not include a heating operation of the heating part, the failure determination is not executed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a hot water device provided with a circulation pump incorporating a water flow determination circuit capable of determining the presence or absence of water flow in a circulation passage, and performing a failure determination before a combustion operation is performed.

Background Art

[0002] Conventionally, a circulation pump has been provided in a circulation passage arranged so that hot and cold water circulates between a bathtub or a hot water storage tank and a heat exchanger, and a hot water device having a chasing boiling function or the like for circulating the hot and cold water in the bathtub by the circulation pump has been widely put to practical use.

[0003] However, when there is no hot and cold water in the bathtub during chasing boiling, dry burning occurs when a combustion operation is performed by a heat exchanger, which may cause a failure or damage to the hot water device. Therefore, it has been necessary to determine whether or not hot and cold water is flowing in the bathtub circulation passage in advance before the combustion operation. Thus, a technique has been conventionally adopted in which water flow detection means such as a water flow switch is provided in the circulation passage, and the combustion operation is performed only when the water flow switch detects the water flow.

[0004] In this water flow detection means using the water flow switch, a signal of "water flow present" is transmitted when the water flow is detected during the operation of the circulation pump, and a signal of "no water flow" is transmitted when the water flow is not detected during the stop of the circulation pump. On the other hand, during an abnormality, a signal of "water flow present" is transmitted during the stop of the circulation pump, or a signal of "no water flow" is transmitted during the operation of the circulation pump. In this case, a failure of the water flow switch is determined.

[0005] In recent years, microcomputer-equipped circulation pumps that can determine the presence or absence of water flow using a circulation pump instead of a water flow switch have come into practical use. For example, Patent Document 1 and Patent Document 2 disclose examples of providing a determination circuit having determination means for determining the presence or absence of water flow in a circulation pump. These determination circuits are incorporated into the circulation pump, detect the power consumption, rotational speed, and operation command voltage of the motor of the circulation pump, calculate a determination value from the detection results, and determine that there is a fluid flow in the circulation passage if the determination value is within the threshold range, and determine that there is no fluid flow in the circulation passage if it is outside the threshold range.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the circulation pumps of Patent Document 1 and Patent Document 2, since a determination circuit is incorporated into the circulation pump instead of a water flow sensor, there is a problem that when the circulation pump itself fails or the determination circuit incorporated in the circulation pump fails, it is impossible to correctly detect the presence or absence of water flow in the circulation passage.

[0008] Therefore, an object of the present invention is to provide a hot water device provided with failure determination means for performing failure determination before combustion operation when a circulation pump incorporating a determination circuit capable of determining the presence or absence of water flow in a circulation passage is adopted.

Means for Solving the Problems

[0009] The hot water device of the invention according to claim 1 is a hot water device comprising a circulation passage, a heating unit for heating the hot water flowing through this circulation circuit, a circulation pump for circulating the hot water, and control means for controlling the heating unit and the circulation pump. The circulation pump includes an impeller, a motor for rotationally driving the impeller with a drive voltage input from the control means, 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. The hot water device further includes a determination means for determining the presence or absence of the flow of hot water using a determination value calculated from the rotational speed and power consumption of the motor detected by these detection means. In the hot water device, the control means has a failure determination means for determining the failure of the determination means. When the operation of the circulation pump is an operation accompanied by a heating operation by the heating unit, the failure determination means determines the failure of the determination means. When the operation of the circulation pump is an operation not accompanied by a heating operation by the heating unit, no failure determination is performed.

[0010] According to the above configuration, when the operation of the circulation pump is an operation accompanied by a heating operation by a heat exchanger such as an automatic operation or a reheating operation, the failure determination means determines the failure of the circulation pump or the water flow determination circuit built in the circulation pump. Therefore, it is possible to prevent in advance the occurrence of dry burning when it is determined that there is water flow in the circulation passage when there is actually no water flow, ensuring safety. On the other hand, when the operation of the circulation pump is an operation not accompanied by a heating operation by a heat exchanger such as an anti-freezing operation or a microbubble warm bath operation, unnecessary energy consumption can be reduced by not performing a failure determination.

[0011] The hot water device of the invention according to claim 2 is, in the invention according to claim 1, characterized in that when a predetermined time has not elapsed since the previous failure determination, even if the operation of the circulation pump is an operation accompanied by a heating operation by the heating unit, no failure determination is performed.

[0012] According to the above configuration, if a predetermined time has not elapsed since the previous failure determination, since there is a high possibility that there is no failure, it is possible to reduce the wasted energy consumption by not performing the failure determination. In addition, although the noise and vibration slightly increase when the circulation pump is operated at the maximum rotational speed during the failure determination, this can be reduced.

[0013] The hot water device according to the invention of claim 3 is characterized in that, in the invention of claim 1 or claim 2, when the control means performs a failure determination by the failure determination means, the rotational speed of the circulation pump is driven at the maximum rotational speed. According to the above configuration, when performing the failure determination, since the rotational speed of the circulation pump is driven at the maximum rotational speed, the amount of water flow in the circulation passage increases, and it is possible to easily determine the presence or absence of water flow, improving the reliability of the determination of the presence or absence of water flow and ensuring safety.

Advantages of the Invention

[0014] According to the hot water device of the present invention, by performing a failure determination of a circulation pump having a water flow detection function in the circulation passage before performing the combustion operation, various effects as described above can be obtained.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0016] Hereinafter, modes for carrying out the present invention will be described based on examples.

Examples

[0017] First, the configuration of the bath water heater 1, which is a hot water device, will be described with reference to FIG. 1. The bath water heater 1 is a combustion type water heater that heats the city water supplied as shown by the arrow W with the combustion heat of the fuel gas and supplies the hot water adjusted to a predetermined temperature to the outside as shown by the arrow HW. However, it may also be a water heater having other heat source machines such as a heat pump type heat source machine. This bath water heater 1 performs a hot water supply operation of supplying hot water at a preset hot water supply set temperature. Further, the bath water heater 1 performs a supplementary heating operation of pouring hot water at a preset bath set temperature into the bathtub 3 up to a preset set water level to fill the bathtub, and heating the hot water in the bathtub 3 to the bath set temperature and returning it to the bathtub 3.

[0018] The bath water heater 1 includes a fuel gas supply unit 11, a blower fan 12 that supplies combustion air, a water heating burner 13 and a bath burner 14 that burn the 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 bath heat exchanger 16 that heats the hot water in the bathtub 3. A water supply flow rate sensor 18 for detecting the flow rate of the city water is disposed in the 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.

[0019] In order to control various operations such as the control of the distribution ratio of the distribution valve 19 based on the detected flow rate and the like of the water supply flow rate sensor 18 and the combustion control of the water heating burner 13, the bath water heater 1 is provided with a control unit 20 (control means). 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 bath heat exchanger 16, a neutralizer 21 containing a neutralizing agent is equipped.

[0020] 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 city water in the water heating heat exchanger 15. This heated hot water is supplied to the hot water outlet passage 22 and is mixed with the city water from the water supply bypass passage 23 that branches from the water supply passage 17 and is connected to the hot water outlet passage 22 at the distribution valve 19, and the temperature is adjusted.

[0021] When the hot water supply destination is, for example, a hot water tap (not shown), hot water adjusted to the set hot water temperature is supplied. When the hot water supply destination is the bathtub 3, hot water adjusted to the bathtub set temperature is poured through a circulation adapter 32 connected to a pouring passage 25 provided with a pouring valve 24. The pouring flow rate into the bathtub 3 is detected by a pouring flow rate sensor 26 disposed on the upstream side of the pouring valve 24. The control unit 20 calculates the amount of poured hot water poured into the bathtub 3 based on this pouring flow rate and the pouring time.

[0022] A circulation passage 28 equipped with a circulation pump 27 is connected to the bathtub heat exchanger 16 to circulate the hot water in the bathtub 3. The control unit 20 drives the circulation pump 27 and causes combustion with the bathtub burner 14 to control a reheating operation of heating the hot water in the bathtub 3 sucked from the circulation adapter 32 and circulated through the circulation passage 28 by the bathtub heat exchanger 16 and returning it to the bathtub 3.

[0023] The pouring passage 25 is connected to the circulation passage 28 via the circulation pump 27. During 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 circulation passage 28.

[0024] A water level sensor 29 for detecting 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 fluctuation of the water level of the bathtub 3. A bathtub temperature sensor 30 for detecting the hot water temperature of the bathtub 3 is disposed on the downstream side of the circulation pump 27 in the circulation passage 28. The hot water temperature of the bathtub 3 is detected in a state where the circulation pump 27 is driven and the hot water is circulated through the circulation passage 28. Incidentally, the water level sensor 29 may be disposed in the circulation passage 28.

[0025] The bathtub water supply device 1 has an operation terminal for performing start operations of reheating operation, hot water supply set temperature, bathtub set temperature, various setting operations such as set water level, etc. 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, 5a for displaying setting information and the like and voice output units 4b, 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.

[0026] Next, failure determination control for determining a failure of a water flow presence / absence determination means for determining the presence / absence of the water flow of the circulation pump and water flow presence / absence determination control of the circulation passage 28 will be described with reference to FIGS. 2, 3, and 4. 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.

[0027] 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 method. As the voltages input to the control circuit 37, there are a power supply voltage Vcc, a command voltage Vsp, and a motor drive voltage Vm, and these are supplied from the control unit 20.

[0028] A motor rotation speed signal composed of a pulse signal 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.

[0029] 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. 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.

[0030] Next, the failure determination control will be described based on the flowchart of FIG. 3. The control program of this failure determination control is pre-stored in the control determination circuit 38, and Si (i = 1, 2,...) in the figure indicates each step.

[0031] In S1, the operation of the bath pump 27 is started. In S2, it is determined whether it is a combustion operation mode in which combustion is performed by the bath heat exchanger 16. If the determination in S2 is Yes, then in S3, it is determined whether a certain time has elapsed since the normal determination was confirmed by the previous failure determination control. Here, the "certain time" is about 2 to 3 hours. If the determination in S2 is No, the process proceeds to "normal operation" in S13 and then to the water flow presence / absence determination process in S14.

[0032] If the determination in S3 is Yes, then in S4, it is determined based on the detected water level of the water level sensor 29 whether the water level in the bathtub 3 is equal to or higher than a predetermined water level. Here, the "predetermined water level" is set to a water level above the circulation adapter 32 that is necessary to operate the bath pump 27 to suck up the hot water in the bathtub 3 from the circulation adapter 32. This is because if the water level is below the circulation adapter 32, air will enter the circulation passage 28, so it is necessary to prevent this.

[0033] When the determination in S4 is No, in S5, it is determined whether it is the first time to pour hot water into the bathtub 3. When the determination in S5 is Yes, in S6, a predetermined amount of hot water is poured into the bathtub 3. Here, the "predetermined amount" of the hot water poured into the bathtub 3 is, for example, 10 L. The hot water adjusted to the bath set temperature is poured through the hot water pouring passage 25, the hot water pouring flow rate into the bathtub 3 is detected by the hot water pouring flow rate sensor 26, and the control unit 20 calculates the hot water pouring amount poured into the bathtub 3 based on this hot water pouring flow rate and the hot water pouring time. When the predetermined amount is finished pouring, it returns to S4.

[0034] When the determination in S5 is No, in S7, a bathtub water level error is notified and it proceeds to S1 2 and advances. For example, the user is notified by display or voice such as "Please check the bathtub water level." on the display units 4a, 5a and the voice output units 4b, 5b of the bathroom remote control 4 and the kitchen remote control 5.

[0035] Here, when the determination in S5 is No, it means that more than two hot water pouring commands have been issued within a certain period of time. In the first hot water pouring, for example, 10 L, that is, even though the hot water has been poured up to the water level above the circulation adapter 32 in the bathtub 3, it is determined in the S4 determination that the water level is not above the circulation adapter 32. This is considered to be due to some kind of failure, so the user is notified of the error. After the error is displayed in S7, it proceeds to S12 and the process ends by stopping the operation.

[0036] On the other hand, when the determination in S4 is Yes, it proceeds to S8. In S8, the rotation speed of the bath pump 27 is commanded to be maximum (for example, 6000 rpm) and it proceeds to S9. Here, the reason for operating the bath pump 27 at the maximum rotation speed is to make it easier to detect the water flow in S9.

[0037] Next, in S9, the presence or absence of water flow is detected by the water flow presence or absence determination means of the bath pump 27. When the determination in S9 is Yes, it proceeds to the combustion operation in S10. If the water flow is detected in S9, it means that the hot water is circulating in the circulation passage 28, and there will be no problem of dry burning even if the combustion operation is performed by the bath heat exchanger 16.

[0038] If the determination in S9 is No, the process proceeds to S11, and an error is notified regarding the presence or absence of water flow determination means of the bath pump 27 or an abnormality of the bath pump 27 itself. If the water flow cannot be detected by the circulation pump 27 even though the rotation speed of the bath pump 27 is at maximum operation in S8, it is considered that there is an abnormality in the bath pump 27 itself or an abnormality in the water flow presence / absence determination means built into the bath pump 27. After an error is notified in S11, the process proceeds to S12 and the operation is stopped.

[0039] Next, the flowchart of the water flow presence / absence determination control shown in FIG. 4 will be described. In the figure, Si (i = 1, 2,...) indicates each step. In S21, it is determined whether the operation mode of the pump 27 is a fixed rotation speed operation. The operation of a normal pump is performed at a fixed rotation speed, and the self-priming operation after pouring hot water into the bath is performed at a fixed command voltage operation. If the determination in S21 is yes, the fixed rotation speed operation is continued in S22, and in the next S23, the command voltage Vsp to the pump drive motor 27m is Detection given.

[0040] Next, in S24, 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) In the above, W is the power consumption of the pump drive motor 27m, and N is the rotation speed of the pump 27.

[0041] If the determination in S21 is No, the process proceeds to S25, and the fixed command voltage operation is continued. In the next S26, the rotation speed N of the pump 27 is detected, and then in S27, the determination value D is calculated by the above arithmetic expression (1).

[0042] In S28 following S24 or S27, it is determined whether the determination value D is greater than or equal to a threshold value (for example, 156). When the determination is Yes, it is determined to be in a full water state in S29, and then the process returns. On the other hand, when the determination in S28 is No, the process proceeds to S30 where it is determined that there is an abnormal water flow. Next, in S31, 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)

[0043] Next, in S32, 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 to be in a gas-liquid mixed state in S33, and the operation of pump 27 continues in the next S34, and then the process returns. When the determination in S32 is No, it is determined to be in a water shortage state in S35, the operation of pump 27 is stopped, and then this control is stopped.

[0044] Next, the actions and effects of the above-described failure determination control will be described. When the operation of the circulation pump 27 is an operation involving a heating operation by a heat exchanger such as an automatic operation or a reheating operation, the determination circuit 38 determines a failure of the circulation pump 27 or the water flow presence / absence determination means built in the circulation pump 27 by the failure determination control. Therefore, it is possible to prevent dry burning from occurring in advance by determining that there is water flow in the circulation passage 28 when there is actually no water flow, ensuring safety. On the other hand, when the operation of the circulation pump 27 is an operation not involving a heating operation by a heat exchanger such as an anti-freezing operation or a microbubble warm bath operation, unnecessary energy consumption can be reduced by not performing the failure determination.

[0045] Furthermore, in the presence / absence determination control of the water flow described above, when the determination means determines that the flow of hot and cold water is abnormal, the control means (20, 37, 38) corrects the calculated determination value D, and determines the state of the hot and cold water flow with this corrected determination value E, 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 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, the state of the hot and cold water flow can be accurately determined, and pump control can be performed according to the state of the flow.

[0046] Note that the above embodiment has been described by taking the case where the present invention is applied to the bath water supply device 1 as an example, but 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, control means, etc. In addition, those skilled in the art can implement the above embodiment in a form with various modifications without departing from the spirit of the present invention, and the present invention includes such modified forms.

Explanation of Reference Numerals

[0047] 1 Bath water supply device 16 Bath heat exchanger 20 Control unit 27 Circulation pump 35 Motor 36 Impeller 37 Control circuit 38 Determination circuit

Claims

1. A hot water device comprising a circulation passage, a heating unit for heating the hot and cold water flowing through this circulation circuit, a circulation pump for circulating the hot and cold water, and control means for controlling the heating unit and the circulation pump, wherein the circulation pump includes an impeller, a motor that rotationally drives the impeller with a drive voltage input from the control means, 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 a determination means for determining the presence or absence of the flow of hot and cold water using a determination value calculated from the rotational speed and power consumption of the motor detected by these detection means. In the hot water device, the control means has a failure determination means for determining the failure of the determination means, and when the operation of the circulation pump is an operation accompanied by a heating operation by the heating unit, the failure of the determination means is determined by the failure determination means, and when the operation of the circulation pump is an operation not accompanied by a heating operation by the heating unit, no failure determination is performed. A hot water device characterized by this.

2. The hot water device according to claim 1, wherein the control means does not perform a failure determination even if the operation of the circulation pump is an operation accompanied by a heating operation by the heating unit when a predetermined time has not elapsed since the previous failure determination.

3. The bath water supply device according to claim 1 or claim 2, wherein the control means drives the rotational speed of the circulation pump at the maximum rotational speed when performing a failure determination by the determination means.

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