JP2547142B2 - How to adjust the ignition / extinguishing timing in a 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 water heater of the type in which a gas burner is forcibly ignited when a hot water supply faucet is opened to a certain opening and forcibly extinguished when it is throttled to a certain opening.
In particular, it relates to a method for adjusting the ignition / extinguishing timing of the gas burner.

[0002]

2. Description of the Related Art A hot water supply device of the type shown in FIG. 2 is, for example, a type of hot water supply device for forcibly extinguishing a gas burner when the hot water supply faucet is throttled to a certain opening degree and the amount of hot water supply decreases. This uses hot water that has been preheated by the solar water heater (2), and the water flow circuit (1) is connected to the solar water heater from its upstream side.
(2), a flow meter (10), a temperature sensor (11), a heat exchanger (12) and a hot and cold water mixing type mixing valve (14) are sequentially arranged in this order on the downstream side, and the mixing valve is further provided. A cold water circuit (20) is connected to (14). In addition, the heat exchanger (1
The proportional valve (16) and the upstream main valve (17) are inserted in the gas circuit (19) to the gas burner (15) that heats 2), and these valves and the flow meter (10) described above are inserted. Etc. are electrically connected to the control device (3). Then, when the mixing valve (14) is opened, the flow meter (10) begins to detect the water flow flowing in the water flow circuit (1), and hot water of the set temperature T (for example, 80 ° C) is transferred to the heat exchanger (1
The combustion amount of the gas burner (15) is controlled while feed-forward controlling the opening of the proportional valve (16) so that it is boiled in 2). Then, mixing the cold water supplied from the cold water circuit (20) with the hot water boiled in the heat exchanger (12) to form a mixing valve.
Remove hot water of desired temperature from (14).

In this kind of water heater, the mixing valve (14)
Even if the gas burner (15) is burned with the minimum capacity and the hot water of the set temperature T (for example, 80 ° C) or more is heated and generated in the heat exchanger (12) (for example, the solar water heater ( If hot water is already generated in 2), etc.), the main valve (17) is kept closed to keep the gas burner (15) in a completely extinguished state from the viewpoint of safety. . Less than,
Further details will be described.

The flow rate (Q) measured by the flow meter (10) and the ignition / extinguishing timing have a relationship as shown in FIG. 3, and when the flow rate (Q) measured by the flow meter (10) is less than the ignition flow rate Q2. Maintains the gas burner (15) in a fire extinguishing state, and when the flow rate (Q) increases to the ignition flow rate Q2, sets the gas burner (15) in the ignition state and starts controlling the combustion amount appropriately. When the flow rate (Q) measured by the flow meter (10) is reduced to the extinction flow rate Q1 by gradually squeezing the mixing valve (14) in the open state, the gas burner (1
Even if 5) is burned with the minimum capacity, there is a risk that hot water above the set temperature will be generated in the heat exchanger (12), so the main valve (17) is closed and the gas burner (15) is put into the extinguished state. maintain.
As shown in FIG. 3, the flow rate difference between the ignition flow rate Q2 and the fire extinguishing flow rate Q1 (hereinafter referred to as the differential Q0) is provided because a natural flow rate change (eg, upstream) when tapping operation is performed near this flow rate. This is to prevent a so-called chattering phenomenon in which the gas burner (15) repeats ignition and extinguishing in small increments due to momentary water pressure fluctuations on the side. And as the differential Q0, it is usually "0.7 liter /
It is set to about "minutes".

However, in the conventional water heater, when the water temperature T0 from the solar water heater (2) approaches the set temperature T,
Despite the provision of the differential Q0, there is a problem that the chattering phenomenon occurs in which the gas burner (15) repeatedly ignites and extinguishes in small increments. This problem will be described in more detail.

The ignition flow rate Q2 and the extinguishing flow rate Q1 are measured by the temperature sensor (1
It is set to change depending on the water temperature T0 detected by 1), and the extinguishing flow rate Q1 is usually determined by the following arithmetic expression. Fire extinguishing flow rate Q1 ≤ minimum calorific value R (kilocalories / minute) / (set temperature T-supply water temperature T0) (A) However, when the supply water temperature T0 approaches the set temperature T, the temperature difference ΔT (set temperature T-supply water temperature T0), that is, the denominator of the equation (A) approaches "0" without limit, and even if the supply water temperature T0 changes slightly, the extinguishing flow rate Q1 greatly changes. Therefore, when the supply water temperature T0 approaches the set temperature T, the conversion error when converting the supply water temperature T0 detected by the temperature sensor (11) into a digital signal in the microcomputer of the control device (3) is expressed by the formula (A ), And it extinguishes the fire extinguishing flow rate Q1 greatly. The influence of the conversion error to the digital signal on the fire extinguishing flow rate Q1 increases as the water temperature T0 approaches the set temperature T.
The flow rate error ΔQ1 of the fire extinguishing flow rate Q1 may be greater than or equal to the differential Q0 described above. When the flow rate error ΔQ1 increases or decreases within a width of the differential Q0 or more during the hot water supply operation (during combustion of the gas burner 15), a chattering phenomenon occurs in which the gas burner (15) repeats ignition and extinguishing in small increments.

It should be noted that in the above-mentioned conventional one, the extinguishing flow rate Q1 is calculated by the above equation (A) and the fixed differential Q0 is added to this to determine the ignition flow rate Q2.
Q2 may be set to a value obtained by adding a predetermined value to the value calculated by the above arithmetic expression, and a value obtained by subtracting a fixed differential Q0 from this may be adopted as the extinguishing flow rate Q1. The present invention has been made in view of the above points and includes a "heat exchanger".
A flow meter (10) for measuring the flow rate of water flowing through (12), and a temperature sensor (11) for measuring the temperature of water supplied to the heat exchanger (12).
The ignition flow rate Q2 or the extinguishing flow rate Q1 is set so as to be inversely proportional to the temperature difference ΔT between the set temperature T and the feed water temperature T0 detected by the temperature sensor (11), and the ignition / extinguishing flow rate is set. A differential Q0, which is the difference between the flow rates of Q2 and Q1, is provided, and the gas burner (15) for the heat exchanger (12) is ignited when the flow rate Q measured by the flow meter (10) exceeds the above ignition flow rate Q2. Along with the flow rate Q becomes less than or equal to the fire extinguishing flow rate Q1 in the ignition / extinguishing timing adjusting method for maintaining the gas burner (15) in a fire extinguishing state '', the feed water temperature T0 detected by the temperature sensor (11) is The task is to suppress the chattering phenomenon in which the gas burner (15) repeatedly ignites and extinguishes frequently even when the temperature approaches the set temperature T.

[0008]

[Technical Means] The technical means of the present invention for solving the above-mentioned problem is that "the differential Q0 is increased / decreased and the differential Q0 is set in the opposite direction to the temperature difference ΔT. That's it.

[0009]

The above technical means operates as follows. According to the above technical means, the temperature difference ΔT between the set temperature T and the feed water temperature T0
Since the increasing / decreasing direction and the increasing / decreasing direction of the differential Q0 are set to have an inverse relationship, the differential Q0 becomes large when the temperature difference ΔT becomes small, that is, when the feed water temperature T0 and the set temperature T relatively approach each other.

That is, when the water supply temperature T0 and the set temperature T approach each other and there is a possibility that the error in the extinguishing flow rate Q1 and the ignition flow rate Q2 based on the detection error in detecting the water supply temperature and the conversion error of the microcomputer may be large. The differential Q0, which is the difference in flow rate between the two, becomes large.

[0011]

[Effect] The present invention has the following unique effects. Fire extinguishing flow rate Q1 and ignition flow rate based on detection errors when the feed water temperature T0 approaches the set temperature T and when detecting the feed water temperature and conversion errors of the microcomputer.
When there is a possibility that the error in Q2 is large, the differential Q0, which is the difference between the flow rates of these two, becomes large, so the ignition flow rate Q2 and the extinguishing flow rate Q1 can be clearly distinguished, and the gas burner (15) burns and extinguishes in small steps. It is possible to prevent the inconvenience of repeating.

[0012]

EXAMPLES Examples of the present invention described above will be described below. The water circuit and the like of the water heater embodying the present invention have the same structure as that shown in FIG. Main valve (17) for gas burner (15)
The control program having the contents shown in FIG. 1 is stored in the microcomputer stored in the control device (3) for controlling the proportional valve (16), and the operation of the water heater according to the present invention will be described below. Will be described with reference to FIG. (A). First, it is judged whether or not the flow meter (10) is in the flow rate measuring state, and when it is in the flow rate measuring state, that is, when the measured flow rate exceeds "0", the mixing valve (14) is opened. It is judged that the tap water has been operated and the differential Q0
Is calculated (see the steps of the drawing symbols (70) and (71)).

The differential Q0 is set so as to increase as the feed water temperature T0 approaches the set temperature T (80 ° C. in this embodiment). In this embodiment, the differential Q0 = 100 liters / ((Preset temperature
T-water temperature T0) x (set temperature T-water temperature T0)) ...
Use the arithmetic expression in (B). As a result, the set temperature T and the water supply temperature
The smaller the temperature difference ΔT of T0, the more differential Q0
Becomes larger and these temperature difference ΔT and differential Q0
The increasing and decreasing directions of are in the opposite relationship.

Note that the denominator of the above differential Q0 arithmetic expression is set to the square of (set temperature T-supply water temperature T0), because the extinguishing flow rate is found from the above-mentioned equation (A) for calculating the extinguishing flow rate Q1.
This is because the amount of change in Q1 is inversely proportional to the square of (set temperature T-supply water temperature T0). That is,

[0015]

[Equation 1] (C) and the denominator on the right side of the above equation (C), which indicates the amount of change in the fire extinguishing flow rate Q1, is the square of (set temperature T-supply water temperature T0). In order to increase / decrease the differential Q0 according to the change or increase / decrease of the error, the above formula (B)
The denominator on the right side of was also set to the square of (set temperature T-supply water temperature T0). (I). Next, when the differential Q0 is smaller than "0.7 liter / min", the differential Q0 is set to 0.7 liter (reference numerals (72) and (73)). (C). Next, the calculation of the ignition flow rate Q2 is executed (drawing code (7
See step 4)). That is, the extinguishing flow rate Q1 is calculated using the formula (A) as in the conventional case described above, and the differential Q0 (the differential Q0 is 0 Ignition flow rate by adding 0.7) when less than 0.7
It asks for Q2. (D). Next, when the flow rate (Q) measured by the flow meter (10) is smaller than the above-mentioned ignition flow rate Q2, even if the gas burner (15) is burned with the minimum capacity, the temperature exceeds the set temperature T (80 ° C. in this embodiment). Since hot water is boiled in the heat exchanger (12),
The control operation is returned to the step indicated by the reference numeral (70) without igniting the gas burner (15). On the contrary, when the flow rate (Q) measured by the flow meter (10) is equal to or higher than the ignition flow rate Q2, the main valve (17) is opened to supply gas to the gas burner (15) and the gas burner (1
Ignite 5) to put it in a burning state (see step (76)). (E). The flow rate (Q) measured by the flow meter (10) and the temperature sensor (1
Supply water temperature T0 detected by 1), set temperature T, and heat exchanger (12)
From the heat exchange efficiency, etc., the proportional valve is operated while calculating the combustion amount of the gas burner (15) required to boil the hot water of the set temperature T above.
Control the opening of (16). That is, the hot water supply operation is continued while the feed forward control is being performed (see step (77)). During this hot water supply operation, the detected water temperature (water supply temperature T0) of the temperature sensor (11), which changes with the passage of time, is substituted into the above equation (A) to continue calculating the extinguishing flow rate Q1, and the above flow rate ( Monitor that Q) is less than the fire extinguishing flow rate Q1 (see steps in drawing code (78) (79)).

In this case, under the condition that the hot water is operated near the ignition flow rate Q2, as described above, when the temperature difference ΔT between the feed water temperature T0 and the set temperature T is small, the feed water temperature T0 by the temperature sensor (11) is If even a slight change, the fire extinguishing flow rate Q1 may fluctuate greatly and the gas burner (15) may be extinguished by force,
Under such conditions, the differential Q0 is calculated to be large in the step of the reference numeral (71), so that the difference between the ignition flow rate Q2 and the extinguishing flow rate Q1 becomes large and the gas burner (1
It is less likely that the chattering phenomenon that 5) repeats ignition and extinguishing in small increments will occur. (F). Next, when the flow rate (Q) measured by the flow meter (10) is smaller than the extinguishing flow rate Q1 when the step of the above-mentioned drawing code (79) is executed, even if the gas burner (15) is burned with the minimum capacity. Since hot water that exceeds the set temperature T is heated and generated in the heat exchanger (12) and is in a dangerous state, the main valve (17) is closed (see the step of drawing code (80)) and the control operation is changed to the drawing code. (70)
Return to step.

In the above embodiment, the fire is extinguished by using the formula (A).

Claims (1)

(57) [Claims] 1. A flow meter (10) for measuring the flow rate of water flowing through a heat exchanger (12), and a temperature sensor (11) for measuring the temperature of water supplied to the heat exchanger (12). Then, set either the ignition flow rate Q2 or the extinguishing flow rate Q1 so as to be inversely proportional to the temperature difference ΔT between the set temperature T and the feed water temperature T0 detected by the temperature sensor (11), and at the same time, set the ignition / extinguishing flow rate Q2, A differential Q0, which is the flow rate difference of Q1, is provided, and when the flow rate Q measured by the flow meter (10) exceeds the above ignition flow rate Q2, the gas burner (15) for the heat exchanger (12) is ignited and When the flow rate Q becomes less than or equal to the fire extinguishing flow rate Q1, in the ignition / extinguishing timing adjusting method for maintaining the gas burner (15) in the fire extinguishing state, the differential Q0 is increased or decreased, and the differential Q0 Reverse the increasing / decreasing direction to the increasing / decreasing direction of the temperature difference ΔT. How to adjust the ignition / extinguishing timing in the set water heater.