JP2004264019A - Heating controller for water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent hot water supply characteristic, when supplying water again in intermittent use of hot water in a water heater. <P>SOLUTION: When a water flow switch 22 is turned on in the intermittent use of the hot water, (To-Tc)×Q<SP>2</SP>is calculated based on a set temperature To, an introduced water temperature Tc detected by an introduced water temperature thermistor 24, and a water quantity Q detected by a flow sensor 22, a time from a cock opening up to ignition, i.e. a prepurge time is prolonged when a value calculated therein is small, the time is shortened when the value is large, and overshooting and undershooting are thereby avoided when supplying the water again. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a heating control device for a water heater such as a gas instantaneous water heater or a bath water heater, and more particularly, controls a time period from opening of a hot water outlet to intermittent use of hot water to ignition of a burner. The present invention relates to a heating control device for a water heater as described above.

  In recent years, for the improvement of hot water quality of hot water heaters such as instantaneous gas water heaters and bath water heaters, further ease of use has been demanded especially for intermittent use in the temperature range where the skin is directly applied to the skin such as kitchens and showers. .

  Conventionally, as a method for providing such performance, a tapping temperature at a tapping port side of a heat exchanger is set to be higher than a set temperature, water is mixed with the tapping water, and the mixing rate is adjusted by a variable valve. In some cases, the temperature is adjusted to obtain a constant hot water temperature. However, since a motor, a circuit, and the like for driving the valve are required, the cost is a major drawback.

As a device which aims to improve the intermittent usability without using such a device, there is one disclosed in Japanese Patent Publication No. 1-31108 or Japanese Patent Application Laid-Open No. 2-161255.
For example, the hot water supply disclosed in Japanese Patent Publication No. 1-31108 detects a hot water temperature before the start of hot water supply by a detection signal from a hot water temperature detector provided in a hot water supply pipe on a hot water outlet side of a heat exchanger. The temperature is compared with the reference temperature to determine whether the mode is the initial hot-water mode or the hot-water mode, and the burner is controlled based on a sequence corresponding to each hot-water mode.

On the other hand, in the water heater disclosed in JP-A-2-161255, the burner is ignited after a water flow detection switch (water flow switch) is turned ON based on the hot water temperature before the start of hot water detected by the hot water temperature detector. Or changing the time until the burner is ignited by taking into account the hot water temperature and the flow rate of water per unit time detected by the water amount sensor.
1-31108 JP-A-2-161255

  However, according to the water heater disclosed in Japanese Patent Publication No. 1-31108, the time from opening of the hot water tap to ignition of the burner is always constant in each of the initial hot water supply mode and the re-hot water supply mode. is there. Therefore, when the flow rate of the hot water flowing through the hot water supply pipe per unit time is small due to the degree of opening of the hot water tap, the gas burner is ignited before the hot water in the hot water pipe is not yet sufficiently discharged, so that an overshoot occurs at the time of re-hot water. On the other hand, when the flow rate of hot water is large, there is a problem that ignition of the gas burner is delayed and undershoot is excessively caused.

On the other hand, according to the water heater disclosed in Japanese Patent Application Laid-Open No. 2-161255, the time from opening to ignition of the burner is controlled based on the hot water temperature before the start of hot water detected by the hot water temperature detector. There is a problem that overshoot and undershoot occur depending on the amount of hot water flowing through the pipe at the time of hot water re-discharge.
In addition, even if the time until ignition is controlled by adding the amount of hot water flowing through the piping to this hot water temperature, the overshoot and undershoot still occur due to the difference in the temperature of the hot water at the time of re-starting due to the difference in the incoming water temperature. The problem of shooting can not be solved.

  The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a hot water flowing through a hot water flowing through a pipe at the time of intermittent use of hot water in a hot water supply device. It is an object of the present invention to provide a heating control device capable of constantly obtaining good tapping characteristics by variably controlling the time from opening to ignition of the burner based on the flow rate per unit time. Thus, overshoot or undershoot does not occur at the time of re-starting the hot water, and the desired hot water temperature can be obtained quickly.

The heating control device for a water heater according to claim 1 of the present invention that solves the above-mentioned problems,
A heat exchanger provided with a water inlet pipe and a hot water pipe, a burner for heating the heat exchanger, a water temperature detecting means provided on the water pipe for detecting a water temperature (Tc), A water heater provided with a flow rate detecting means for detecting a flow rate (Q) per unit time of hot water and a tapping temperature setting means for setting a set temperature (To) of hot water discharged from the tapping pipe;
A variable control means for variably controlling the time from opening of the hot water tap to ignition of the burner,
The time from opening of the water tap to ignition of the burner is:
(To-Tc) associated with the value obtained from the equation × Q ^2, and subject matter to be set shorter as the determined value is greater.

According to the heating control device for a water heater according to the present invention having the above configuration, the water supplied to the heat exchanger via the water inlet pipe is heated by the burner and obtained as hot water from the hot water outlet pipe. However, at the start of tapping, the incoming water temperature and the flow rate of water per unit time are detected by input signals from the incoming water temperature detecting means provided in the inlet pipe and the hot water flow rate detecting means provided in the incoming pipe or tapping pipe. It is, and since the hot water temperature is set by the hot water temperature setting means, since the set temperature (to) and the incoming water temperature (Tc) and flow rate (Q) and (to-Tc) × Q ² determined, this value Variable control is performed such that the larger the value, the shorter the time from opening to ignition of the burner.
As a result, immediately after the start of tapping at the time of tapping again, the ignition operation is started early when the amount of hot water (Q) is large, and the ignition operation is delayed when the amount of hot water (Q) is small, and the flow of water is raised to the set temperature. By controlling the time for starting the ignition operation also by the amount of heat ((To−Tc) × Q) required for the above operation, tapping at a desired set temperature can be obtained quickly without overshoot or undershoot.
Therefore, applying this to a gas instantaneous water heater or a bath kettle water heater, etc., makes it possible to quickly obtain hot water with a desired hot water temperature without unexpected hot water or cold water coming out to the user. It is extremely user-friendly, and its industrial benefits are extremely large.

  In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the water heater heating control device of the present invention will be described below.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a gas water heater to which the present invention is applied. In the gas water heater 10 shown in FIG. 1, a heat exchanger 16 in which a water supply pipe 12 and a tapping pipe 14 are provided is disposed in a casing 18, and the heat exchanger 16 is provided in the casing 18. A gas burner 20 for heating is provided.

  The water supply pipe 12 is provided with a water flow switch (flow rate sensor) 22 for detecting the flow and flow rate of water and an input water temperature thermistor 24 for detecting the temperature of the water, and a water governor 26 for regulating the flow of the water. Is also provided. On the other hand, the tapping pipe 14 is provided with a tapping temperature thermistor 28 for detecting tapping temperature.

  On the other hand, a main solenoid valve 32, a main solenoid valve 34 and a gas proportional valve 36 are provided in the gas line 30 of the gas burner 20, respectively, and a blower fan 38 for supplying combustion air to the gas burner 20 is connected. Have been.

The water flow switch (flow rate sensor) 22, the incoming water temperature thermistor 24, the outgoing water temperature thermistor 28 and the like are connected to the input side of the burner controller 40 for controlling the operation of the gas water heater. Is connected to a gas proportional valve 36, a fan motor (not shown) of a blower fan 38, and the like. In addition, a hot water tap 42 is provided at a hot water outlet of the hot water pipe 14.

  In the gas water heater 10, when the hot water tap 42 is opened, the water flow switch (flow rate sensor) 22 is turned on, and the controller is energized to rotate the blower fan 38. Then, after the blower fan rotates and pre-purges, the original solenoid valve 32 and the main solenoid valve 34 are opened, the gas proportional valve 36 performs a gentle ignition operation, and gas is supplied to the gas burner 20. At the same time, the gas burner 20 is ignited by the continuous spark of a spark plug (not shown) by the igniter.

When the mild ignition operation is completed, the proportional control between the gas burner 20 and the blower fan 38 is started. That is, if there is a difference between the hot water temperature detected by the hot water temperature thermistor 28 and the set hot water temperature, the controller 40 determines the difference and sends a signal to the gas proportional valve 36 to adjust the amount of gas supplied to the gas burner 20. The outlet temperature of the heat exchanger 16 is kept constant.

  In addition, a signal is sent from the controller 40 to the fan motor of the blower fan 38 in accordance with a change in the supplied gas amount by the gas proportional valve 36, and control is performed such that the gas amount and the air amount are always maintained in a constant relationship. Thus, the heat exchanger 16 is heated by the combustion gas of the gas burner 20, and the water sent to the heat exchanger 16 via the water supply pipe 12 is heated to a predetermined temperature, and is discharged from the tapping pipe 14 through the hot water tap 42. Is done.

  Next, the control at the time of re-starting the hot water supply according to the present invention will be described with reference to the flowchart shown in FIG. Is displayed as ").

  If it is determined in S1 that the water flow switch 22 has been turned on (S1: "YES"), the process proceeds to the prepurge stage after the rotation of the blower fan 38 as described above. In this embodiment, the prepurge (1) (0 .5 seconds) and pre-purge (2) (variable), and the time from opening to ignition of the gas burner 20 is variably controlled.

That is, in the stage of pre-purge (1), the water flow switch 22 is turned on and a standby state is set for 0.5 seconds (S2). The apparatus is placed in a standby state for a predetermined time determined in accordance with the corrected output value whose value has been corrected (S3). Details of this will be described later.

  After the lapse of the pre-purge (2) in S3, the gas proportional valve 36 and the like of the gas burner 20 are opened to perform a gentle ignition operation, and the ignition of the gas burner 20 is performed by the spark of the spark plug (S4). Thereafter, as described above, the proportional control between the gas burner 20 and the blower fan 38 is started, and the gas supply amount to the gas burner 20 and the blower are determined by comparing the hot water temperature detected by the hot water temperature thermistor 28 with the set temperature. Control of the air supply amount to the fan 38 is performed (S5).

Here, the standby time until ignition in the prepurge (2) will be described. The standby time (T) in the prepurge (2) is determined as follows. That is, the required output of the water heater (the amount of heat given to the water required to raise the flow of water to the set temperature) is expressed by equation (1) in the case of feed forward (FF control). But,
Required output value = C × (To−Tc) × Q [kcal / min] (1)
Here To: Set temperature [° C]
Tc: incoming water temperature [° C]
Q: Flow rate of water per unit time [liter / min]
C: Specific heat of water [kcal / liter ° C]
In the equation (1), the required output of the water heater shown in the equation (1) is not changed because C is considered to be constant, and is not changed. Therefore, a value obtained by further multiplying the equation (1) by the flow rate Q (here Then, it is called the correction required output).
Corrected required output value = Required output value x Q
= (To-Tc) × Q ² [kcal·liter / (min) ² ] (2)

  When the corrected required output value is obtained by calculation, the time (T) (T) (in the prepurge (2)) between the corrected required output value and the ignition time (in prepurge (2)) shown in the graph of FIG. ) Is determined.

  That is, in the relationship diagram shown in FIG. 3, the horizontal axis indicates the required output value of the gas burner, and the vertical axis indicates the time (second) until ignition. As shown by a solid line A in this figure, the time until ignition (time of pre-purge (2)) is constant while the output required for correction is from 0 (zero) to a certain value, and when the output exceeds this value, the correction is performed. As the required output increases, the time until gradual ignition is shortened.

  This means that the large output required for correction means that the flow rate of water is large or the required amount of heat is large. Therefore, the time of the prepurge (2) is shortened accordingly and the gas burner is ignited quickly. This is based on the intention. In this way, an attempt is made to avoid an undershoot at the time of re-watering.

  On the other hand, a small output required for correction means that the flow rate of water is small or the required amount of heat is small. Therefore, the time of the prepurge (2) is lengthened by that much and the ignition of the gas burner is started. It is based on the intention to delay. In this way, an attempt is made to avoid overshoot at the time of re-watering.

  The reason why the pre-purge (2) time until ignition is constant in a range where the output required for correction is from 0 (zero) to a certain value is that the flow rate of water is small during that time, so the ignition time at the time of re-starting hot water Need not be recognized to prevent overshoot and undershoot further (because overshoot and undershoot are controlled by FB control). In particular, the value may not be a constant value and may be represented by a two-dot chain line in FIG.

As described above, according to the above embodiment, the time from opening to ignition is variably controlled according to the degree of opening of the hot water tap 42 at the time of re-hot water supply, that is, according to the flow rate of water flowing through the pipe per unit time and the required amount of heat. Is what is done. In addition, since the control of the time from opening to ignition is performed according to the set temperature, the incoming water temperature, and the flow rate of water per unit time, the tapping at a desired temperature is performed as an advantage of the FF control. Can be obtained quickly.
Therefore, overshoot and undershoot are avoided irrespective of the flow rate of the hot water flowing through the pipe at the time of re-starting hot water, and furthermore, the effect of obtaining hot water at a desired hot water temperature is obtained at once.

  In the above embodiment, the prepurge (1) and the prepurge (2) are separately performed to perform the two-stage control. However, it is not always necessary to divide the prepurge (1) and the prepurge (2). In this case, the ignition time in a state in which the times of the prepurge (1) and the prepurge (2) are added as shown by a virtual line B in FIG. 3 may be determined. In any case, since the time from opening to ignition is controlled by adjusting the prepurge time, the gas line of the gas burner is not opened during that time, and raw gas leaks before ignition. There is no need to worry about this, so the safety in using the equipment is also ensured.

  In addition, the present invention is not limited to the above embodiment at all, and it goes without saying that various design changes and improvements can be made without departing from the spirit of the present invention. For example, in the present invention, since the operation from the opening to the ignition at the time of hot water re-discharge is a problem, the determination of whether the hot water is the re-hot water or the initial hot water is not a problem. There are many ways to do this, so I won't go into that here.

It is a figure showing the schematic structure figure of the water heater concerning one example of the present invention. It is a control flowchart of the water heater shown in FIG. FIG. 7 is a diagram for explaining the relationship between the corrected output value of the gas burner and the time until ignition (time control of prepurge).

Explanation of reference numerals

10 Gas water heater 12 Water supply pipe (water inlet pipe)
14 tapping pipe 16 heat exchanger 20 gas burner 22 water flow switch (flow rate sensor)
24 Inlet water temperature thermistor 40 Burner controller 42 Hot water tap

Claims (1)

A heat exchanger provided with a water inlet pipe and a hot water pipe, a burner for heating the heat exchanger, a water temperature detecting means provided on the water pipe for detecting a water temperature (Tc), A water heater provided with a flow rate detecting means for detecting a flow rate (Q) per unit time of hot water and a tapping temperature setting means for setting a set temperature (To) of hot water discharged from the tapping pipe;
A variable control means for variably controlling the time from opening of the hot water tap to ignition of the burner,
The time from opening of the water tap to ignition of the burner is:
(To-Tc) × associated with the value obtained from the equation Q ^2, the heating control apparatus for water heater characterized in that it is set shorter as the determined value is greater.

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