JP2552586B2 - Inlet water temperature detection method and hot water supply control method in water heater - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an incoming water temperature of a water heater and a method for controlling a hot water supply.
It is possible to control the hot water supply by feed-forward control even if the water temperature sensor for detecting the incoming water temperature is down.

[0002]

2. Description of the Related Art A hot water supply system that realizes a rapid rise of hot water temperature at the initial stage of hot water operation and reduces deviation between the hot water temperature and the set temperature, that is, a so-called feed forward control and feedback control system. There is a water heater that adopts. As shown in FIG. 3, in the water passage (10) connected to the tap (15), the water flow switch (11), the water temperature sensor (12), the flow rate counter (13), and the heat exchanger (1) are arranged from the upstream side. , And hot water temperature sensor (1
4) and in this order. Further, a hot water temperature setting device (2) for setting the hot water temperature is disposed on the wall surface near the hot water faucet (15), and the hot water temperature setting device (2) is provided.
Is applied to a control device (3) having a microcomputer (hereinafter referred to as a microcomputer) built therein, and outputs of the water flow switch (11) and the like are also applied to the control device (3).

In this device, when the tap water tap (15) is opened and the water flow switch (11) outputs an ON signal, a control device (3) incorporating a microcomputer starts the control operation of the tap water temperature. First, the incoming water temperature T detected by the water temperature sensor (12), the set temperature S of the hot water temperature setting device (2), and the flow rate counter (1
The flow rate Q detected by 3) is determined, and the combustion amount q of the gas burner (4) required for boiling the hot water of the set temperature is calculated. Then, feedforward control is executed to control the combustion amount q of the gas burner (4) (to control the opening of the gas proportional valve (40)) according to the calculation result, whereby the hot water temperature at the beginning of hot water discharge is promptly increased. Secure a good start.

Further, the temperature of the hot water obtained by the feed-forward control, which often has a slight deviation from the set temperature of the hot water temperature setting device (2), is corrected to make the temperature of the hot water setting device (2) even higher. Perform feedback control operation in order to approach accurately. That is, the actual hot water temperature detected by the hot water temperature sensor (14) (the temperature of the hot water obtained by the feed-forward control) is continuously compared, and if they do not match, these two temperatures are made to match. In addition, the combustion amount of the gas burner (4) is corrected. As a result, hot water having an accurate temperature that matches the set temperature can be obtained.
When the operation of stopping the hot water discharge is performed, the post fan (17) is driven for a certain period of time in order to cool the heat exchanger (1) part and suppress the post-boiling phenomenon in the part.

Further, the above-mentioned conventional apparatus which executes the feed-forward control and the feedback control has the advantages that the initial hot water temperature rises quickly and the hot water temperature can be secured accurately. However, in the above-mentioned conventional one, it is necessary to incorporate a water temperature sensor (12) for detecting the incoming water temperature T of the supply water (tap water) to the heat exchanger (1) in order to have a feed-forward control function. The water temperature sensor (1
As the number of required parts increases due to the requirement 2),
There is a problem that the failure rate increases as the number of parts increases.

Further, in the above-mentioned conventional one, since the water temperature sensor (12) for detecting the water temperature T entering the heat exchanger (1) is required, if this fails, the hot water at the initial stage of the hot water discharge operation is required. There is an inconvenience that the hot feed forward control is disabled and the smooth hot water discharge operation does not proceed. [Regarding the invention of claim 1] The invention of claim 1 is made in view of the above-mentioned point, and the water temperature can be determined without providing an independent water temperature sensor for detecting the water temperature entering the water heater. The task is to get them.

[0007]

[Technical Means] The technical means according to claim 1 for solving the above-mentioned problem is to "drive the post fan (17) to cool the heat exchanger (1) after the operation of stopping hot water discharge, and to heat the heat exchanger. When (1) is cooled for a certain period of time, the lowering temperature Δt detected by the hot water temperature sensor (14) arranged near the downstream side is judged, and the lowering temperature Δt is used to increase the lowering temperature Δt. The outside temperature Z which becomes low is estimated, and the outside temperature Z
Is assumed to be the temperature T of the water entering the heat exchanger (1) at the time of the next tapping operation. ”

[0008]

The above technical means operates as follows. When the tapping operation is performed, the water temperature T (the temperature of the water supplied to the heat exchanger (1)) estimated at the preceding tapping operation is simulated as the tap water temperature T at the tapping operation this time. . That is, when each hot water discharge operation is stopped, the post fan (17) is driven to cool the heat exchanger (1), and when the heat exchanger (1) is cooled for a certain period of time, the heat is generated in the vicinity of its downstream side. The lowering temperature Δt detected by the provided hot water temperature sensor (14) is determined. Since the outside temperature Z is lower as the decrease temperature Δt is larger and there is a relationship of outside temperature Z = −K × reduction temperature Δt + A (where K and A are constants), the calculation / determination is performed based on the knowledge. The outside temperature Z is assumed to be the incoming water temperature T to the heat exchanger (1) at the next hot water operation.

[0009]

The invention of claim 1 has the following unique effect. Even if there is no independent temperature sensor for detecting the incoming water temperature T to the heat exchanger (1), the incoming water temperature T can be estimated, so that the temperature sensor for detecting the incoming water temperature is not provided or the temperature sensor fails. Even if it is, the hot water supply temperature T can be utilized to enable the hot water supply operation by the food howard control.

[Invention of Claim 2] The invention of Claim 2 relates to the invention of which the essential parts of the invention indispensable to the industrial field of use and the structure are the same as those of the invention of Claim 1 above. "In the initial stage of tapping operation, the water temperature of the supply water to the heat exchanger (1), the flow rate of the supply water, and the set temperature of the hot water temperature setting device (2) are judged to calculate the combustion amount of the gas burner (4). Perform feed-forward control to control,
After executing the feed-forward control, the heat exchanger (1)
Hot water supply control adapted to execute feedback control for determining the temperature detected by the hot water temperature sensor (14) for detecting the hot water discharged from the hot water and controlling the combustion amount of the gas burner (4) so that this temperature approaches the set temperature. Method ”, an independent water temperature sensor for detecting the temperature of water entering the heat exchanger (1) is unnecessary, and the number of required parts is reduced.

[0011]

[Technical Means] In order to solve the above-mentioned problems, the technical means of the invention of claim 2 is to "drive the post fan (17) to stop the heat exchanger (1) by cooling the heat exchanger (1) after the operation of stopping hot water discharge. When the exchanger (1) is cooled for a certain period of time, the lowering temperature Δt detected by the hot water temperature sensor (14) arranged near the downstream side of the exchanger (1) is determined, and the lowering temperature Δt is used to determine the lowering temperature Δt. Estimate the outside temperature Z that becomes lower as the value increases,
The outside air temperature Z is used as the heat exchanger (1) for the next tapping operation.
It is assumed that the incoming water temperature T to the water is controlled, and the feed forward control can be performed based on the incoming water temperature T and the flow rate Q ”.

[0012]

The above technical means operates as follows. When the tapping operation is performed, the incoming water temperature T to the heat exchanger (1) at the next tapping operation is obtained as in the case of the first aspect of the invention. Then, by utilizing the incoming water temperature T and the flow rate counter (1
Next, feed forward control at the beginning of the next hot water discharge operation is performed based on the next flow rate Q, etc. measured by 3).

[0013]

The invention of claim 2 has the following unique effects. Since the water temperature T can be estimated without providing a temperature sensor for determining the water temperature T entering the heat exchanger (1), the number of required parts can be reduced as the temperature sensor is not required.

[0014]

Embodiments of the inventions of claims 1 and 2 will be described below. As shown in FIG. 1, the water heater used for implementing the inventions of claims 1 and 2 is the conventional one described above except that it does not include a water temperature sensor for measuring the water temperature T entering the water heater. Is configured similarly to.

That is, in the water passage (10), from the upstream thereof, a water flow switch (11), a flow rate counter (13), a heat exchanger (1), a hot water temperature sensor (14) and a hot water tap (15).
And the gas burner (4)
A post fan (17) is provided in the exhaust passage of the heat exchanger (1) heated by. Further, the water flow switch (11), the flow rate counter (13), etc. are wired and connected to a control device (3) incorporating a microcomputer, and the control device (3) has a hot water temperature setting device (2). Wiring is connected.

A program for controlling an appliance is written in the microcomputer of the control device (3), and the contents of the control program will be described with reference to FIG. . First, when the power is turned on, the value of the incoming water temperature T is initially set to 15 ° C. (see step (81) in the drawing).

[0017] By watching the output of the water flow switch (11), the opening operation of the tap water faucet (15) is monitored (see the step (82) in the drawing), and when the tap water tap (15) is operated to open, The amount of combustion of the gas burner (4) is controlled while performing feed forward control using the value and the flow rate Q measured by the flow rate counter (13) (see step (83) of the drawing). The water temperature T is
A value of 15 ° C. initially set by “” is adopted at the first hot water discharge operation after the power is turned on, and a hot water temperature T calculated by “to” described later is adopted at the second hot water discharge operation and thereafter.

.. Next, in order to bring the temperature of the hot water obtained by the feed forward control closer to the set temperature t of the hot water temperature setting device (2), the actual temperature of the hot water generated by the heat exchanger (1) is determined. While performing feedback control to supply hot water (see step of drawing reference numeral (84)).

[0019] The output of the water flow switch (11) is judged and the closing of the hot water tap (15) is monitored (see step (85) of the drawing), and the hot water tap (15) is closed and the hot water tapping operation is stopped. If confirmed, the water input temperature T to the heat exchanger (1) required at the time of feed forward control at the beginning of the next hot water discharge operation is estimated. That is, the temperature detected by the hot water temperature sensor (14) when hot water is stopped is stored in the microcomputer as the hot water stop temperature t1, and then the post fan (17) is driven to start cooling the heat exchanger (1) ( (See step 86 of drawing reference number).

[0020] When the post fan (17) continues to be driven for 30 seconds, the post fan (17) is stopped and the hot water temperature sensor (14) at that time is stopped.
The detected temperature of is stored in the microcomputer as the cooling temperature t2 (see steps of reference numerals (87) and (88) in the drawing).

[0021]. Next, the above-mentioned tapping stop temperature t1−cooling temperature t2 is set as the lowering temperature Δt, and the larger the lowering temperature Δt, the lower the outside air temperature. Therefore, “the outside air temperature Z = −K × the lowering temperature Δt”
t + A (however, K and A are constants) "to estimate the outside air temperature at that time. Then, the outside temperature Z is simulated as the incoming water temperature T at the time of the next hot water operation (drawing sign (8
The instrument control is returned to the step (82) again.

As described above, according to the above, feedforward control can be performed without providing an independent temperature sensor for detecting the incoming temperature T of the feed water supplied to the heat exchanger (1). In the above embodiment, the step of drawing symbol (81) for initially setting the incoming water temperature T to 15 ° C. is executed when the power is turned on, but the hot water supply is performed only by the feedback control of the drawing symbol (84) at the first hot water discharge operation. The operation may be started.

In the above embodiment, the water heater of the type having no water temperature sensor on the upstream side of the heat exchanger (1) has been described, but a water temperature sensor is provided in both upper and lower flow passages of the heat exchanger (1). In the hot water supply device of the type including the hot water temperature sensor (14), the above invention can be applied when the water temperature sensor fails. In this case, since the incoming water temperature can be estimated from the outgoing hot water temperature detected by the outgoing hot water temperature sensor (14), when the failure signal of the water temperature sensor is generated, feedforward control in the initial hot water operation can be performed using the estimated incoming water temperature. Become.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a water heater used for implementing the present invention.

FIG. 2 is a flowchart showing a control program applied to the implementation of the invention of claims 1 and 2.

FIG. 3 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 (1) ・ ・ ・ Heat exchanger (2) ・ ・ ・ Hot water temperature setting device (4) ・ ・ ・ Gas burner (14) ・ ・ ・ Hot water temperature sensor (17) ・ ・ ・ Post fan

Claims (2)

(57) [Claims] 1. A post fan (17) after the operation of stopping hot water discharge.
Is driven to cool the heat exchanger (1), and when the heat exchanger (1) is cooled for a certain period of time, a decrease temperature Δt detected by a hot water temperature sensor (14) arranged near the downstream side of the heat exchanger (1). The lowering temperature Δt is used to estimate the outside air temperature Z that decreases as the decreasing temperature Δt increases, and the outside air temperature Z is determined by the incoming water temperature T to the heat exchanger (1) during the next tap water operation. Water temperature detection method for water heaters that is assumed to be. 2. Combustion of a gas burner (4) at the initial stage of tapping operation by judging the water temperature of the feed water to the heat exchanger (1), the flow rate of the feed water, and the set temperature of the hot water temperature setting device (2). Calculate amount
The feed-forward control to be controlled is executed, and after the feed-forward control is executed, the detection temperature of the tap water temperature sensor (14) for detecting the tap water temperature of the hot water flowing out of the heat exchanger (1) is judged to be the set temperature. In the hot water supply control method in which feedback control for controlling the combustion amount of the gas burner (4) is performed so as to approach, the post fan (17) is driven to cool the heat exchanger (1) after the hot water supply stop operation. When the heat exchanger (1) is cooled for a certain period of time, the lowering temperature Δt detected by the hot water temperature sensor (14) arranged near the downstream side is determined, and the lowering temperature Δt is used to reduce the lowering temperature Δt. The outside temperature Z, which becomes lower as the temperature Δt increases, is estimated, and the outside temperature Z is simulated as the incoming water temperature T to the heat exchanger (1) at the time of the next hot water discharge operation, and based on the incoming water temperature T and the flow rate Q. Phil If possible, tighten the hot water supply control method the Dohowado control.