JPH0658530A - Combustion control device for hot water supply heater - Google Patents

Abstract

PURPOSE:To secure stabilized operation of a combustion burner even if there exists variability in the performance of electronic sensor components, such as water volume sensor or inlet water or hot water supply thermistor installed to a hot water supply heater or combustion gas whose heating values vary is adopted. CONSTITUTION:A CPU 32 computes an actual combustion output volume of a combustion burner 24 and determines the value based on input signals transmitted from a water quantity detection sensor 16, a water inlet thermistor 18 and a hot water supply thermistor 20, thereby controlling the opening of a gas proportional valve 28 and the rotary speed of blower fan 30. In addition to that, there is further adopted a higher precision instrument which computes and corrects a proportional factor between the rotary speed of the fan 30 for a hot water heater and the opening of the gas proportional valve 28 based on a reference gas and determines the rotary speed of the fan 30 based on the corrected operation data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater, and more specifically, to a gas provided in a gas pipeline for supplying a fuel gas to the burner, which supplies air to a combustion burner provided in the water heater. The present invention relates to a combustion control device for a water heater, which controls according to the opening of a proportional valve.

[0002]

2. Description of the Related Art Conventionally, this type of water heater adjusts the opening of the gas proportional valve provided in the gas line of the combustion burner in accordance with the current value of the gas proportional valve to supply gas to the combustion burner. And the rotation speed of the blower fan that supplies combustion air to the combustion burner is controlled according to the current value of the gas proportional valve.

However, in such a conventionally known water heater, the combustion capacity of the combustion burner varies when the gas proportional valve is fully opened due to differences in the calorific value of the supply gas and fluctuations in the gas pressure. May result in a shortage or excess of combustion air.

In that case, for example, the maximum opening of the gas proportional valve is detected, the actual combustion output (actual combustion output) of the combustion burner is obtained based on the detection signals from the temperature sensor and the flow rate sensor of the water heater, and the actual combustion is obtained. The output is compared with the designated output stored in advance in the control device, and if the actual combustion output is larger than the designated output when the gas proportional valve is fully opened, the rotation speed of the blower fan is increased. 15140
It is known from the publication.

Further, as shown in, for example, Japanese Utility Model Laid-Open No. 3-96557, in order to avoid erroneous determination that the output is over when the actual combustion output is not over, the actual combustion is performed for a predetermined time when the gas proportional valve is fully opened. In some systems, the fan rotation speed is increased only when the output is larger than the designated output, and when it is not, the fan rotation speed is controlled by the proper fan rotation speed.

[0006]

However, in any of the above-mentioned control devices, the manufacturing variations and design variations of the flow rate sensor, the temperature thermistor, etc., which are the basis for calculating the actual combustion output of the combustion burner, are completely taken into consideration. It has not been. Therefore, when the actual combustion output is obtained based on the detection signals from these sensors, thermistors, etc., it may be determined that the actual combustion output has exceeded the designated output, although it has not actually exceeded. Then, there is a problem in that the blower fan increases the number of revolutions, which causes combustion abnormality such as liftback due to excess combustion air, or an increase in noise.

The present invention has been made to solve such a problem, and an object thereof is to provide a blower fan by combustion control in which variations in manufacturing and design of flow rate sensors, temperature thermistors, etc. are corrected. It is an object of the present invention to provide a combustion control device for a water heater, which ensures an appropriate number of revolutions. This avoids combustion abnormalities such as liftback due to excess combustion air, and eliminates unnecessary noise.

[0008]

In order to achieve this object, a combustion control device for a water heater according to the present invention includes a flow rate detecting means provided in a water passage leading to a heat exchanger, a temperature of water entering the heat exchanger, and A temperature detecting means for detecting the temperature of hot water discharged from the heat exchanger, a combustion burner for heating the heat exchanger, a gas proportional valve provided in a gas conduit leading to the combustion burner, and a blower fan for sending combustion air to the combustion burner. And calculating the combustion output of the combustion burner based on the output signals from the flow rate detecting means and the temperature detecting means, adjusting the opening of the gas proportional valve based on the calculation result, and adjusting the opening of the gas proportional valve. In a water heater equipped with a controller that responds to control the rotation speed of the blower fan, the combustion output of the combustion burner is measured in advance by a high-precision instrument at the factory before product shipment, and the measured value and the combustion bar Determined by calculation error between the combustion output value, and a correction calculating means for correcting the correlation coefficient between the rotational speed and the gas proportional valve opening of the air blowing fan based on the calculated value.

[0009]

According to the combustion control device for a water heater according to the present invention having the above structure, the combustion output of the combustion burner is calculated based on the output signals from the flow rate detecting means and the temperature detecting means,
The opening of the gas proportional valve is adjusted based on the calculation result.At that time, the rotation speed of the blower fan is based on the calculated value obtained by multiplying the gas proportional valve opening by the correlation coefficient corrected by the correction calculating means. It is proportionally controlled by the controller. Therefore, an erroneous determination that the combustion output is excessive or insufficient due to variations in the flow rate detecting means, the temperature detecting means, etc. is avoided, and the blower fan is rotationally controlled to an appropriate value by the appropriate rotational speed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in the water heater 10 of this embodiment, a water amount detection sensor 16 is provided in a water passage 14 leading to the heat exchanger 12, and the heat exchanger 1 of the water passage 14 is provided.
2 A water inlet thermistor 18 for detecting the water inlet temperature is provided on the water inlet side, and a hot water outlet thermistor 20 for detecting the outlet water temperature is provided on the hot water outlet side of the heat exchanger 12.

On the other hand, the combustion burner 24 for heating the heat exchanger 12 is provided with a gas proportional valve 28 in a gas line 26 for supplying a fuel gas to the combustion burner 24, and the combustion burner 24 is also provided with a gas proportional valve 28. Is connected to a blower fan 30 for supplying combustion air. Then, the water amount detection signal from the water amount detection sensor 16 and the incoming water thermistor 18
The detection signal of the inflow water temperature by and the detection signal of the outflow temperature by the hot water discharge thermistor 20 are input to the controller 32,
A command signal from the controller 32 is sent to the gas proportional valve 28 and the blower fan 30, and the controller 3
The opening degree of the gas proportional valve 28 is adjusted by the command signal from 2 and the rotation speed of the blower fan 30 is controlled.

In this embodiment, when the faucet 22 provided at the outlet of the water channel 14 is opened, water flows through the water channel 14, and when the faucet 22 is opened, the water amount detecting sensor 1
6 detects the water flow, and based on the signal, the spark plug (not shown) of the combustion burner 24 is sparked, and the combustion burner 24 is automatically ignited.

FIG. 2 is a block diagram of the controller 32 of the water heater 10. The central processing unit (CPU) 32 receives the detection signals from the water amount detection sensor 16, the water inflow thermistor 18, and the hot water thermistor 20 described above, and when these detection signals are input, the CPU 32
Then, from the water amount (W) detected by the water amount detection sensor 16, the water inlet temperature (TC) detected by the water inlet thermistor 18 and the hot water temperature (TH) detected by the hot water thermistor 20, the combustion output amount of the combustion burner 24 ( Q) can be obtained by the following arithmetic expression.

[0014]

[Equation 1]

When the actual combustion output amount (Q) is obtained, the RAM 36 connected to the CPU 32 has the relational data between the combustion output amount (Q) and the proportional valve current value (i) of the gas proportional valve 28. And the CPU based on this data
A control signal is output from 32 to the proportional valve drive circuit 38, and the proportional valve current value i of the gas proportional valve 28 changes corresponding to the combustion output amount, thereby controlling the proportional valve opening (gas amount). .

Further, the fan rotation speed (N) of the blower fan 30
And the proportional valve current value (i) of the gas proportional valve 28 are also stored in the RAM 36, and the fan 32 is rotated by the CPU 32 based on this functional expression. ) Is determined and a control signal is output from the CPU 32 to the fan drive circuit 42, whereby the rotation speed of the blower fan 30 is controlled.

[0017]

[Equation 2]

N: fan speed i: proportional valve current value

The proportional valve current value which controls the opening of the gas proportional valve 28 is detected by the proportional valve current detection sensor 40, and this detection signal is input to the CPU 32 and C
The PU 32 determines whether or not the proportional valve current value has reached the maximum value (io) based on the signal from the proportional valve current detection sensor 40. Further, a rotation speed sensor 44 is attached to the blower fan 30, and a signal from the rotation speed sensor 44 is input to the CPU 32, so that the fan rotation speed is feedback-controlled. The ROM 34 connected to the CPU 32 stores a program for executing the above-described various arithmetic processes and an execution program for comparing and discriminating the combustion output amount and the designated output amount.

Thus, this water heater has a manufacturing variation and a design in advance at the time of assembling and shipping in the factory line by using a high precision measuring instrument in advance to detect various kinds of detection sensors such as the water amount detection sensor 16, the water entering thermistor 18, and the hot water thermistor 20. The combustion output amount (Q) of the combustion burner 24 due to the variation of the above is measured. This measurement is performed using a reference fuel gas whose calorific value is known in advance. That is, the reference gas is sent to the combustion burner 24, and the water amount detection sensor 1 at that time is sent.
6. The combustion output amount of the combustion burner 24 is obtained by a highly accurate measuring instrument based on the detection signals from the water inflow thermistor 18 and the hot water thermistor 20.

FIG. 3 shows the relationship between the combustion output (output) amount (Q) determined by the CPU 32 of the water heater itself and the fan rotation speed (N) of the blower fan 30 at that time, and highly accurate measurement. Actual combustion output (output) amount (Q) and fan speed (N) of the water heater determined by the instrument
It is shown by comparing with the relationship with. Output amount (Q) obtained by the CPU 32 of the water heater 10 itself
And the fan speed (N), the fan speed (N) is 40 when the output amount (Q) is 350 Kcal / min.
It is assumed that the fan rotation speed (N) is 1500 rpm when the output amount (Q) is 67 Kcal / min at 00 rpm. Corresponding to this, the relationship between the actual output (Q) of this water heater and the fan speed (N) measured using a high precision measuring instrument is that the output (Q) is 390 Kcal / min. Fan speed (N) is 4000 rpm, output (Q) is 75 Kca
It is assumed that the fan speed (N) is 1500 rpm at l / min.

Then, in the present invention, the fan rotation speed (N) is adjusted so that the relationship between the output amount (Q) of the water heater 10 and the fan rotation speed (N) actually matches the measurement value of the high precision measuring instrument. And the combustion output (output) amount (Q), that is, the fan rotation speed (N) shown in the above-mentioned equation 2.
And the coefficient in the function of the gas proportional valve current value (i) are corrected. Based on this correction function, the function data of the proportional valve current value (i) and the fan rotation speed (N) of the RAM 36 are rewritten.

[0023]

[Equation 3]

N ': fan speed by correction

Next, considering the case where this water heater is actually installed at the site, the amount of water (W) detected by the water amount detection sensor 16 by the burner controller 32 of the water heater and the water input thermistor 18 are detected by using the local gas. The amount of combustion output (output) (Q) of the combustion burner 24 is calculated from the input water temperature (TC) and the outlet temperature (TH) detected by the outlet hot water thermistor 20, and the fan of the blower fan 30 at that time is calculated. Number of rotations (N ')
Is determined on the basis of the correction function shown in the above equation 3.

For example, as shown in FIG. 4, assuming that the output amount (Q) obtained by the controller 32 by using the local gas is 416 Kcal / min (> 390 Kcal / min), the fan rotation speed at that time (N ') is calculated as 4270 rpm by the correction function shown in Equation 3. If the output amount (Q) obtained by the controller 32 by using the local gas is 80 Kcal / min (> 75 Kcal / min), the fan rotation speed (N ') at that time is 1600 rpm by the correction function of Expression 3. Is required. At this time, the proportional valve current value (i) is determined only by the output amount (Q) obtained by the calculation by the controller 32 of the water heater, and the value does not change. Only the fan speed (N ') is output. It depends on the amount (Q).

On the other hand, when the combustion gas (output) amount (Q) decreases due to the decrease of the local gas supply pressure, the output obtained by the controller 32 of the water heater as shown in FIG. 5, for example. Quantity (Q) is 300 Kcal / min (<39
0 Kcal / min), the fan rotation speed (N ') at that time is also 30 by the correction function shown in the above-mentioned Equation 3.
The output amount (Q) calculated as 80 rpm and calculated by the water heater controller 32 is 50 Kcal / min (<
If it is 75 Kcal / min), the fan rotation speed (N) at that time is also calculated as 1000 rpm by the correction function of Expression 3.

Therefore, the danger that carbon monoxide gas (CO gas) increases due to incomplete combustion due to insufficient supply of combustion air, or the flame is blown out and extinguished due to excessive supply of combustion air is avoided. It is also possible to deal with the case where the supply pressure gradually decreases after a certain time has passed after the burner ignition. It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0029]

As is apparent from the above description, the water heater according to the present invention takes into consideration variations in manufacturing or design of water amount detection sensors and various electronic sensor parts such as water inflow thermistors and hot water thermistors. As a result, the rotational speed of the blower fan corresponding to the gas proportional valve opening of the combustion burner is corrected and controlled, so that proper control of the rotational speed of the blower fan improves the energy efficiency of the blower fan and reduces noise. It is possible. Further, it is possible to avoid a combustion trouble due to insufficient supply or excessive supply of combustion air, and to secure a stable combustion state.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a water heater according to an embodiment of the present invention.

FIG. 2 is a control block diagram of the water heater shown in FIG.

FIG. 3 is a diagram illustrating a basis for calculating a fan rotation speed of a blower fan from a combustion output (output) amount of a water heater measured by a high precision measuring instrument.

FIG. 4 is a diagram illustrating a function that determines a fan rotation speed of a blower fan from a combustion output (output) amount of this water heater by using local gas.

FIG. 5 is a diagram showing a relationship for determining the fan rotation speed of the blower fan from the amount of combustion output (output) of the water heater by using the local gas, illustrating the case where the gas supply pressure decreases. Is.

[Explanation of symbols]

 10 Water Heater 12 Heat Exchanger 14 Water Channel 16 Water Quantity Detection Sensor 18 Inlet Water Thermistor 20 Hot Water Thermistor 24 Combustion Burner 26 Gas Pipeline 28 Gas Proportional Valve 30 Blower Fan 32 CPU 34 ROM 36 RAM 38 Proportional Valve Drive Circuit 40 Proportional Valve Current Detection Sensor

Claims (1)

[Claims] 1. A flow rate detecting means provided in a water passage leading to the heat exchanger, a temperature detecting means for detecting a temperature of water entering the heat exchanger and a temperature of hot water discharged from the heat exchanger, and a combustion burner for heating the heat exchanger. And a gas proportional valve provided in a gas pipe leading to the combustion burner, and a blower fan that sends combustion air to the combustion burner.The combustion output of the combustion burner is determined based on the output signals from the flow rate detection means and the temperature detection means. A water heater equipped with a controller that controls the opening of the gas proportional valve based on the calculated value and controls the rotation speed of the blower fan in response to the opening of the gas proportional valve. In the factory, the combustion output of the combustion burner is measured in advance by a high-precision instrument, the error between the measured value and the combustion output value of the combustion burner is calculated, and the blower fan is calculated based on the calculated value. Water heater combustion control apparatus characterized by comprising a correction calculation means for correcting the correlation coefficient between the rotational speed and the gas proportional valve opening.