JP2020020565A - Electric water heater - Google Patents

Abstract

To provide an electric water heater capable of supplying hot water having a temperature that is very close to a set temperature and is stable.SOLUTION: An electric water heater includes: a heat source 1 for heating water; a discharge section 15 for delivering hot water heated and produced by the heat source; temperature setting means 8 for setting a temperature of hot water delivered from the discharge section 15; temperature detection means 9 for detecting the temperature of the hot water delivered from the discharge section 15; and control devices (10, 11). During delivery of hot water from the discharge section 15, the control devices (10, 11) calculate a difference between a set temperature set by the temperature setting means 8 and a temperature detected by the temperature detection means 9, and execute PID control on the basis of the difference. In the electric water heater, when the state where the difference is less than a predetermined value is continued for a predetermined time, the control devices (10 11) fix output amount of the heat source 1.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an electric water heater.

  A conventional electric water heater has a sheath heater as a heat source in a device, and discharges hot water heated by the electric heater from a discharge unit such as a shower head (for example, see Patent Document 1).

JP 2013-250015 A

  However, in a conventional electric water heater, feedback control is always performed using a temperature sensor for detecting the tapping temperature so that the tapping temperature is maintained at the set temperature, so that the tapping temperature becomes stable around the set temperature. However, since the temperature detected by the temperature sensor fluctuates to some extent, the output of the electric heater also fluctuates up and down little by little.

  In addition, when the tapping flow rate suddenly decreases, the output of the electric heater also fluctuates to cope with it, but when the tapping flow rate is small, the change in tapping temperature corresponding to the output variation of the electric heater increases. Therefore, there is also a problem that the tapping temperature tends to be unstable with respect to the set temperature.

  An object of the present invention is to solve the above-mentioned conventional problems and to provide an electric water heater that can supply hot water at a temperature very close to a set temperature and at a stable temperature.

  In order to solve the conventional problem, an electric water heater of the present invention includes a heat source for heating water, a discharge unit for discharging hot water heated and generated by the heat source, and a hot water discharged from the discharge unit. Temperature control means for setting the temperature, temperature detection means for detecting the temperature of the hot water discharged from the discharge unit, and a control device, while the hot water is discharged from the discharge unit, the control device, In an electric water heater that calculates a difference between a set temperature set by a temperature setting unit and a temperature detected by the temperature detection unit and performs PID control based on the difference, the difference is smaller than a predetermined value. When the state continues for a predetermined time, the control device fixes the output amount of the heat source.

  As a result, since the output fluctuation of the heat source can be suppressed, the hunting phenomenon in which the tapping temperature changes vertically due to the output fluctuation of the heat source can be reduced, and as a result, hot water having a temperature very close to the set temperature and having a stable temperature can be obtained. An electric water heater that can be supplied can be provided.

  According to the present invention, it is possible to provide an electric water heater that can supply hot water that is extremely close to a set temperature and that is stable.

Configuration diagram of electric water heater according to Embodiment 1 of the present invention Configuration diagram of the electric circuit of the electric water heater The figure which shows the control block of the same electric water heater Control flowchart of the output of the heat source of the electric water heater Diagram showing the relationship between tapping temperature and time of the electric water heater

  A first invention provides a heat source for heating water, a discharge unit for discharging hot water heated and generated by the heat source, a temperature setting unit for setting a temperature of the hot water discharged from the discharge unit, and Temperature control means for detecting the temperature of the hot water to be supplied, and a control device, wherein the control device sets the temperature set by the temperature setting means while the hot water is supplied from the discharge section; In an electric water heater that calculates a difference from the temperature detected by the detection means and performs PID control based on the difference, when the state in which the difference is less than a predetermined value continues for a predetermined time, the control is performed. The apparatus is an electric water heater characterized in that an output amount of the heat source is fixed.

  As a result, since the output fluctuation of the heat source can be suppressed, the hunting phenomenon in which the tapping temperature changes vertically due to the output fluctuation of the heat source can be reduced, and as a result, hot water having a temperature very close to the set temperature and having a stable temperature can be obtained. An electric water heater that can be supplied can be provided.

  According to a second aspect, in the first aspect, when the temperature detected by the temperature detecting means is lower than the set temperature, and when the temperature difference is less than a predetermined value, the temperature difference is set to a predetermined value. The gain value in the PID control is smaller than the above case.

  As a result, water having a temperature lower than the set temperature is heated by the heat source and rises in temperature. When the temperature approaches the set temperature, the value of the gain in the PID control becomes smaller, and the water is heated by the heat source and rises in temperature. It is possible to provide an electric water heater that can quickly adjust hot water to a set temperature and supply hot water at a stable temperature.

  In a third aspect of the present invention, in the first or second aspect, the heat source includes a plurality of electric heaters, and the control device outputs an electric power to each of the plurality of electric heaters. The adjustment is performed.

  Thus, since the heat source is composed of a plurality of electric heaters, it is possible to control the output of the heat source with finer precision than in the case where the heat source is composed of one electric heater.

  For this reason, even in a time zone in which it is determined whether or not the difference is less than the predetermined value for a predetermined time or more, the fluctuation range of the hunting of the tapping temperature is suppressed, and the output amount of the heat source is set to a constant value. It becomes easy to fix, and further stabilization of the tapping temperature can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by the embodiment.

(Embodiment 1)
FIG. 1 is a configuration diagram of the electric water heater in the first embodiment. FIG. 2 is a configuration diagram of an electric circuit of the electric water heater in the first embodiment. FIG. 3 is a diagram showing a control block of the electric water heater.

  First, the configuration of the electric water heater according to Embodiment 1 will be described with reference to FIGS. 1, 2, and 3.

  As shown in FIG. 1, the electric water heater in the first embodiment is a heat source for heating water, and includes a heater unit 1 including a plurality of electric heaters.

  That is, the heater unit 1 includes a first heater 2 which is an electric heater and a second heater 3 which is also an electric heater.

  A first triac 4 serving as power control means for the first heater 2 and a second triac 5 serving as power control means for the second heater 3 are provided.

  Further, the electric water heater in the first embodiment has a flow rate switch 6 for detecting the amount of supplied water, a tapping switch 7 used when a user desires tapping, and a user adjusting the tapping temperature. Temperature control unit 8 as a temperature setting unit, temperature sensor 9 as a temperature detection unit for detecting the temperature of hot water heated by heater unit 1, first control device 10, second control device 11, earth leakage breaker 12, It has.

  The electric water heater according to the first embodiment includes a water supply port 13 to which water for heating is supplied, and a water supply port 14 which is an outlet of hot water heated by the first heater 2 and the second heater 3. And a shower head 15 which is connected to a hot water supply port 14 and is a discharge section from which hot water is discharged.

  Further, the electric water heater according to Embodiment 1 includes an electric circuit as shown in FIG. 2 and a control block as shown in FIG.

  That is, a microcomputer is mounted on the first control device 10, and the microcomputer includes a DC power supply, a zero-cross signal, a detection signal of the tap switch 7, a signal of the flow rate switch 6, a signal of the temperature control 8, a temperature sensor, and the like. 9 is received.

  Then, the microcomputer outputs a power control signal to the first triac 4 and the second triac 5. The outputs of the first heater 2 and the second heater 3 are controlled via the first triac 4 and the second triac 5, respectively.

  In addition, a transformer is mounted on the second control device 11, converts external AC power into DC power, and supplies power to the microcomputer and other control elements.

  Next, the operation and action of the electric water heater according to the first embodiment of the present invention will be described.

  When the user turns on the tap switch 7, the first controller 10 and the second controller 11 are energized, and then the flow switch 6 is turned on (for example, water of 1.0 L / min or more flows). Then, the microcomputer mounted on the first control device 10 determines the temperature based on the set temperature of the temperature volume 8 as the temperature setting means and the tapping temperature detected by the temperature sensor 9 as the temperature detecting means. Then, the output amount required for each of the first heater 2 and the second heater 3 is calculated.

  Then, the microcomputer controls the first heater 2 and the second heater 3 via the first triac 4 and the second triac 5 so as to output the calculated required output amount.

  The first heater 2 and the second heater 3 heat the water supplied from the water supply port 13 with the output amount obtained by the operation of the microcomputer built in the first control device, and generate heat. The hot water is supplied to the user through a hot water supply port 14 and a shower head 15 which is a discharge unit.

  When the user wants to adjust the temperature of the hot water flowing out of the shower head 15, the user changes the set temperature with the temperature volume 8.

  FIG. 4 is a control flowchart of the output of the heat source of the electric water heater in the first embodiment.

  FIG. 4 shows a control flow of the output of the first control device 10 of the heater unit 1 which is composed of the first heater 2 and the second heater 3 and is a heat source.

  First, it is determined from the signal input of the flow switch 6 whether or not the flow switch 6 is ON (S1).

  If it is determined that the flow rate switch 6 is ON, a difference (temperature deviation) between the temperature set by the temperature control unit 8 as the temperature setting unit and the tapping temperature detected by the temperature sensor 9 as the temperature detecting unit is calculated ( S2).

  Then, a PID control operation is executed based on the temperature deviation, and an output amount required for the heater unit 1 is calculated (S3).

  The PID calculation is a type of feedback control, in which a proportional term, a differential term, and an integral term are calculated from the difference between the current value and the target value, respectively, and then summed to obtain a control amount (here, the output amount required for the electric heater). ) Is determined. The proportional term, derivative term and integral term are calculated using constants of the proportional gain, derivative gain and integral gain, respectively.

  Here, when the tapping temperature detected by the temperature sensor 9 as the temperature detecting means is lower than the temperature set by the temperature volume 8 as the temperature setting means, and when the temperature difference is less than the predetermined value δ, The microcomputer mounted on the first control device 10 is set so that the respective values of the proportional gain, the differential gain, and the integral gain are smaller than when the temperature difference is equal to or greater than the predetermined value δ.

  Before feeding back the calculated required output amount to the heater unit 1, the microcomputer determines whether the heater output is fixed at the same output amount as that at the previous output or updated to the calculated output amount. Do it.

  That is, the microcomputer determines whether or not the state where the temperature deviation is less than the predetermined value α has continued for the predetermined time β or more (S4).

  The temperature difference, which is the difference between the temperature set by the temperature volume 8 as the temperature setting means and the tapping temperature detected by the temperature sensor 9 as the temperature detecting means, is kept under the predetermined value α for a predetermined time β or more. If so, the condition is satisfied, no feedback is performed, the value calculated by the PID calculation control is ignored, and the output to the heater unit 1 is fixed to the same output amount as the previous output (S5). ).

  In this case, each of the first heater 2 and the second heater 3 is simultaneously fixed to the same output amount as that at the time of the previous output.

  The temperature difference, which is the difference between the temperature set by the temperature volume 8 as the temperature setting means and the tapping temperature detected by the temperature sensor 9 as the temperature detecting means, is kept under the predetermined value α for a predetermined time β or more. If not, the condition is not satisfied, and the value calculated by the PID calculation control is reflected and fed back to the heater unit 1 to output the value calculated by the PID calculation control (S6).

  In this case, the output adjustment is performed for each electric heater of the first heater 2 and the second heater 3.

  After that, the time is measured by a time measuring means (not shown) (S7), and the control is repeated every predetermined time γ until the flow switch 6 is turned off.

  FIG. 5 is a diagram showing a relationship between tapping temperature of the electric water heater and time in the first embodiment.

  That is, FIG. 5 is a graph showing a temporal change of the tapping temperature, and shows a temperature change of the tapping temperature until the output amount to the heater unit 1 is fixed at a constant value.

  The tapping temperature rises until it reaches the set temperature, but even if the tapping temperature approaches the set temperature, the temperature detected by the temperature sensor 9 fluctuates to some extent, so feedback control is always performed. In such a case, the tapping temperature may hunt (change up and down in small increments).

  However, even if the hot water temperature fluctuates up and down immediately after the hot water temperature reaches the set temperature, the temperature set by the temperature potentiometer 8 as the temperature setting means and the temperature sensor as the temperature detecting means as shown in FIG. If the temperature deviation that is the difference between the tapping temperatures detected in step 9 is less than a predetermined value α and the state has continued for a predetermined time β or more, the output amount to the heater unit 1 is fixed to a constant value. Thus, hunting of tapping temperature can be suppressed.

  Further, since the heater unit 1 is constituted by a plurality of electric heaters of the first heater 2 and the second heater 3, finer accuracy is obtained as compared with the control in the case of being constituted by one electric heater. Can control the output of the heater unit 1.

  For this reason, the tapping temperature is determined in the time zone (time region of the predetermined time β in FIG. 5) in which it is determined whether the state where the temperature deviation is less than the predetermined value α has continued for the predetermined time β or more (S4). Can be reduced, and the output amount to the heater unit 1 can be easily fixed to a constant value.

  As described above, the electric water heater according to the first embodiment has a temperature deviation which is a difference between the temperature set by the temperature potentiometer 8 as the temperature setting means and the tapping temperature detected by the temperature sensor 9 as the temperature detecting means. However, when the state below the predetermined value is continued for a predetermined period of time, it is determined that the tapping temperature is stable to some extent, and the output amount to the heater unit 1 is fixed to a constant value, so that the hunting of the tapping temperature is performed. The temperature can be suppressed and the tapping temperature can be stabilized.

  In the electric water heater according to the first embodiment, the heater unit 1 serving as a heat source is configured by a plurality of electric heaters, so that the state in which the temperature deviation is less than the predetermined value α continues for the predetermined time β or more. In the time period (S4) in which it is determined whether or not there is a temperature fluctuation (the time region of the predetermined time β in FIG. 5), the fluctuation amount of the hunting of the tapping temperature can be suppressed, so that the output amount to the heater unit 1 is fixed at a constant value. It becomes easier to stabilize the tapping temperature.

  As described above, the electric water heater of the present invention is extremely close to the set temperature, and can supply hot water at a stable temperature. Therefore, an electric heater is used as a heat source for electric showers, electric water heaters, electric pots, and the like. Applicable to hot water heaters.

1 heater unit (heat source)
2 First heater 3 Second heater 4 First triac 5 Second triac 6 Flow switch 7 Hot water switch 8 Temperature volume (temperature setting means)
9 Temperature sensor (temperature detection means)
DESCRIPTION OF SYMBOLS 10 1st control apparatus 11 2nd control apparatus 12 Earth leakage breaker 13 Water supply port 14 Hot water supply port 15 Shower head (discharge part)

Claims (3)

A heat source for heating water,
A discharge unit for discharging hot water generated by heating with the heat source,
Temperature setting means for setting the temperature of hot water discharged from the discharge section,
Temperature detection means for detecting the temperature of hot water discharged from the discharge section,
And a control device,
While hot water is flowing from the discharge section,
In the electric water heater, wherein the control device calculates a difference between the set temperature set by the temperature setting unit and the temperature detected by the temperature detection unit, and performs PID control based on the difference.
When the state where the difference is less than a predetermined value continues for a predetermined time,
An electric water heater, wherein the control device fixes an output amount of the heat source. When the temperature detected by the temperature detecting means is lower than the set temperature, when the temperature difference is less than a predetermined value, the gain value in the PID control is larger than when the temperature difference is equal to or more than the predetermined value. The electric water heater according to claim 1, wherein is smaller. The said heat source is comprised from a some electric heater, The said control apparatus performs output adjustment for every electric heater among the said several electric heaters, The Claim 1 or Claim 2 characterized by the above-mentioned. Electric water heater.

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