JP2010185605A - Combustion control method for burning appliance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion control method capable of preventing incomplete combustion in a burning appliance for a long time. <P>SOLUTION: To obtain blowing air quantity necessary for satisfying required heat quantity in a combustion part, when electric power drive is performed with a predetermined applied voltage and a predetermined drive current to achieve the predetermined rotational frequency of a fan motor in accordance with a predetermined relational expression etc., an actual drive current actually applied to the fan motor is detected, and based on a predetermined relational expression etc. during normal combustion, air quantity equivalent heat quantity to be obtained at the detected actual drive current value is calculated. The pressure difference between the secondary gas pressure of fuel gas to be supplied and combustion chamber pressure is detected, and heat quantity corresponding to the pressure difference is determined as pressure difference equivalent heat quantity, based on the predetermined relational expression etc. during normal combustion. The difference between the determined pressure difference equivalent heat quantity and the air quantity equivalent heat quantity is detected. When the difference becomes a predetermined difference or more, drive current to a flow control valve is lowered to reduce fuel gas supply amount to the combustion part or supply of fuel gas is cut off. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a combustion control method for a combustion device that supplies and burns fuel and combustion air to a combustion section, and more particularly to an improvement for reliably preventing the generation of carbon monoxide accompanying incomplete combustion.

  In the case of gas instantaneous water heaters and other various types of combustion equipment, if carbon monoxide CO is contained in the exhaust gas from the exhaust port as a result of incomplete combustion in the combustion part, it can be extremely fatal. Needless to say, it can lead to dangerous situations. For this reason, various safety measures and environmental measures have been taken.

  For example, a technique for measuring the carbon monoxide concentration or oxygen concentration in the exhaust gas to prevent the exhaust gas from deteriorating is described in Patent Document 1 below.

JP-A-9-287737

  Certainly, this Patent Document 1 discloses a technique for directly measuring and controlling the concentration of carbon monoxide in the exhaust gas and the oxygen concentration instead of this, so that these concentration detection sensors (exhaust gas sensors) are normally used. As long as it is functioning, control can be performed to stop combustion when the carbon monoxide emission becomes an abnormal amount.

However, in this prior art, it has been found that deterioration of the sensor itself due to water vapor H ₂ O contained in the exhaust gas is not taken into consideration, which is a problem. That is, according to the knowledge of the present inventor, it is certain that such a sensor will be deteriorated by water vapor. For this reason, the reliability of the sensor over a long period of time can be reduced only by such conventional technology. It was concluded that it was difficult to ensure safety as a combustion device.

  The present invention was made in view of this point, and is not an exhaust gas sensor-dependent method in which reliability is impaired by water vapor in the exhaust gas. Furthermore, we intend to provide a combustion control method that can reduce exhaust gas deterioration, including monitoring in the electric quantity dimension.

In order to achieve the above object, the present invention
Fuel gas from a gas proportional valve that is an electric flow control valve and air blown from an electric fan motor are supplied to the combustion section, and the required amount of heat required from time to time for combustion in the combustion section A combustion control method for a combustion device to obtain
In order to obtain the air volume necessary to satisfy the required heat quantity, power is supplied at a predetermined applied voltage and a predetermined drive current so that the fan motor has a predetermined number of revolutions according to a predetermined relational expression or relation table. When driving, the actual drive current that is the value of the drive current actually applied to the fan motor is detected, and a predetermined relational expression or relationship table when normal combustion is performed in the combustion section And the air volume equivalent heat quantity that should be obtained at the time of the actual drive current value detected at that time,
A differential pressure between the secondary gas pressure, which is the pressure of the fuel gas supplied to the combustion section, and the combustion chamber pressure, which is the pressure in the combustion chamber, is detected and predetermined when normal combustion is performed in the combustion section. The amount of heat corresponding to the differential pressure at that time is obtained as the amount of heat equivalent to the differential pressure based on the relational expression or the relationship table.
The difference between the calculated heat equivalent to the differential pressure and the air volume equivalent is detected, and if this difference exceeds a predetermined value, the drive current to the flow control valve is reduced to reduce the amount of fuel gas supplied to the combustion section. Reduce or cut off fuel gas supply;
A combustion control method characterized by the above is proposed.

  In the present invention, the fuel gas supply is cut off after satisfying this basic configuration, and even if the fuel gas supply amount is reduced, the difference between the differential pressure equivalent heat quantity and the air quantity equivalent heat quantity has a predetermined magnitude. It is also proposed to do so when the above-mentioned state becomes a predetermined time or longer.

  Of course, when the fuel gas supply is shut off, a visual or audible or visual and audible abnormality alarm means may be driven.

  According to the present invention, since it is a mechanical element in a sense, it is not dependent on an exhaust gas sensor including instability factors, and even if the same sensor is used, a pressure sensor, a highly reliable and inexpensive sensor, is used to From the pressure difference between the gas pressure and the combustion chamber pressure, it is possible to know the gas flow rate given to the combustion section from time to time, and thereby to know the abnormality of the exhaust system and the intake system. Then, by comparing the degree of the abnormality with the monitoring result based on the monitoring of the electric quantity actually used for the fan motor control, an effective defense against incomplete combustion can be taken. That is, according to the present invention, it is possible to extend the life of the combustion equipment itself while maintaining high reliability by a relatively inexpensive means.

It is a flowchart in one Embodiment of the combustion control method of this invention. It is a schematic block diagram in an example of the combustion control apparatus which can apply the method of this invention.

  FIG. 1 shows a flow chart of a preferred embodiment of the combustion control method of the present invention, and FIG. 2 shows the case where a gas water heater such as a gas flash heater is assumed as an example of a combustion apparatus to which the present invention can be applied. A schematic configuration of the device is shown. However, the present invention is not limited to this, and may be a heating device or the like. In short, the present invention can be applied to any combustion device that supplies and burns fuel and combustion air to the combustion section.

  First, as shown in FIG. 2, the start and stop of fuel supply to the combustion section (burner) 11 is controlled by a gas electromagnetic valve 13 that opens and closes according to a command from the control circuit 10. An electric gas proportional valve (flow control valve) 14 adjusts the gas supply amount according to the required fuel amount. The circuit configuration, member configuration, and the like for that purpose are already known in existing combustion equipment, and will not be described in further detail. In the present invention, as an additional member, the pressure of the fuel gas supplied to the burner 11 is two. A secondary gas pressure sensor 31 is provided between the gas proportional valve 13 and the burner 11, and a combustion chamber pressure sensor 32 for detecting the pressure in the combustion chamber is provided in the combustion chamber. The control circuit 10 can generally be configured to include a microcomputer, and various data and the table (relation table) described below are stored in a nonvolatile memory attached to the data or stored in a rewritable or rewritable manner. Is done.

  In addition, the hot water supply system may be of a known and existing structure. In FIG. 2, only the heat exchanger 21 heated by the combustion in the burner 11, and the water supply system and the hot water system for the heat exchanger 21 are schematically shown. Is shown. A water supply temperature sensor 16 and a water amount sensor 17 are provided in the water supply system, and a tapping temperature sensor 18 is provided in the tapping system. The water volume sensor 17 may be provided on the side of the hot water system. The combustion air is supplied to the burner 11 by an electric fan motor 14 whose rotation speed is adjusted by controlling the applied power (applied voltage, drive current) by the control device 10. A rotation speed sensor 15 is provided.

  However, under such a physical configuration, in the present invention, exhaust gas deterioration is reduced and safety is ensured by the following method. As will be described with reference to FIG. 1, when power is supplied to the combustion equipment, the control device 10 enters a function start state as indicated by start in step 50. Under this state, as shown in step 51, the control device 10 reads the setting information set by the user via setting means (not shown). Typical setting information is the hot water temperature desired by the user, and this is the set temperature in the combustion equipment at that time. Of course, in the case of a heater, the desired output temperature is the set temperature.

  When the user makes a hot water discharge request by twisting a faucet (not shown) (the control device 10 knows that the water amount sensor detects the generation of water), combustion control starts (step 52), and an ignition mechanism (not shown) In accordance with the start of combustion in the burner 11, the control device 10 first tentatively sets the target heat amount {(set temperature-) according to the feed water temperature obtained from the feed water temperature sensor 16 and the water amount obtained from the water amount sensor 17. (Water supply temperature) × water quantity} is calculated (step 53). In the case of a heater, the temperature around the combustion device or the room temperature is a temperature corresponding to the feed water temperature.

  Actually, the hot water temperature detected by the hot water temperature sensor 18 often does not become the set temperature at the target heat amount.Furthermore, based on the difference between the actual hot water temperature obtained from the hot water temperature sensor 18 and the set temperature, A required heat quantity {target heat quantity + (set temperature-tapping water temperature) × water quantity}, which is a value that takes into account the corrected heat quantity of the target heat quantity, is calculated (step 54). If it is a heater, the output air temperature actually sent out of the combustion equipment corresponds to the hot water temperature.

  In any case, the control device 10 determines the amount of fuel gas supplied to the burner 11 using a relational expression or a relational table stored in advance in a nonvolatile memory in accordance with the required heat quantity required at that time. Apply a drive current that should be the valve opening corresponding to the gas proportional valve 13 (step 55), and in order to give the burner 11 the necessary air volume (supply air volume) to satisfy the required heat quantity, this is also non-volatile in advance. The target rotational speed of the fan motor 14 is determined according to a relational expression or a relation table stored in the memory, and a predetermined power, that is, a predetermined applied voltage and a predetermined driving current are calculated so as to obtain the target rotational speed. (Step 56).

  Thereafter, the control device 10 takes in the actual rotational speed, which is the actual rotational speed of the fan motor 14 obtained through the rotational speed detection sensor 15, and compares it with the target rotational speed set in advance (step 57) If the difference is greater than or equal to a predetermined value, the drive current applied to the fan motor 14 is adjusted to make the actual fan motor rotational speed equal to the target rotational speed, as shown in step 58.

  Under this state, the control device 10 detects an actual drive current that is the value of the drive current that is actually applied to the fan motor 14 at that time. If the exhaust port 19 provided in the combustion device is clogged, the fan motor 14 will increase in speed because the load becomes lighter if the drive current value is the same according to the clogging ratio. Is controlled to be equal to the target rotational speed, the detected actual drive current value is smaller than the necessary drive current value under normal conditions.

  Therefore, as shown in Step 59-1, the control device 10 first detects the actual drive current value from the detected actual drive current value when there is no problem in the combustion system, particularly the exhaust system including the exhaust port 12, and under normal operating conditions. The amount of air to be delivered by the fan motor 14, which is planned when the drive current is large, that is, the amount of air, and the amount of heat associated with the amount of air in advance in a relational expression or relationship table are obtained as the amount of air equivalent to the amount of air.

  Next, as shown in step 59-2, the differential pressure between the current secondary gas pressure obtained from the secondary gas pressure sensor 31 and the same combustion chamber pressure obtained from the combustion chamber pressure sensor 32 is detected. The amount of heat corresponding to the pressure difference at that time is obtained as the amount of heat corresponding to the pressure difference based on a predetermined relational expression or table when normal combustion is performed in the combustion section.

  By the way, if the exhaust port 19 becomes obstructive, the combustion chamber pressure rises compared to the normal time, and if the intake system becomes obstructive, it decreases conversely, so see the difference between the combustion chamber pressure and the secondary gas pressure As a result, the flow rate of the gas actually supplied to the burner 11 at that time can be indirectly detected. Until now, there has been no case where attention has been paid to the correlation between the actual change in the gas flow rate accompanying the change in the pressure difference and the anticipated change in the combustion heat amount associated therewith.

  However, once the air volume equivalent heat quantity and the differential pressure equivalent heat quantity are obtained, the difference between the differential pressure equivalent heat quantity and the air quantity equivalent heat quantity is then detected as shown in step 60, and this difference is determined in advance. Compare if it is not over the tolerance. If there is no problem in the intake / exhaust system, there is no significant difference between the actual drive current and the previously determined applied current under the condition that the actual rotational speed of the fan motor is not significantly different from the target rotational speed. Since the given gas flow rate should be in a value range that is recognized as normal in advance, the difference between the air volume equivalent heat quantity and the differential pressure equivalent heat quantity is also within the allowable range. Therefore, in this case, the routine returns to step 53 and the routine so far is repeated.

  However, if it is detected that there is a difference greater than the allowable value between the air volume equivalent heat quantity and the differential pressure equivalent heat quantity, it is considered that some problem has occurred in the intake and exhaust systems. In the embodiment, first, in the next step 61, the gas proportional valve 13 is set so as to have a valve opening suitable for a required heat amount (a value smaller than the initial required heat amount) predetermined according to the difference. The drive current is calculated and adjusted to decrease, and the amount of combustion is restricted to be lower than the initial required heat amount, thereby preventing the occurrence of incomplete combustion. Naturally, at this time, the limited current value becomes the upper limit in the gas proportional valve current calculation in step 55 described above.

  After this, if the same monitoring routine is repeated and the drive current is adjusted, but the limit state of the applied current to the gas proportional valve 13 cannot be released for a predetermined time, for example, about 3 minutes or more, it is desirable. Step 62 is provided, and that is determined here. As shown in Step 63, the control device 10 is operated to close the gas solenoid valve 12 and shut off the supply of combustion gas, or at least a speaker or piezoelectric (not shown) An audible alarm such as a sounding body or a light emitting diode or a visual or audible / visible alarm means such as a liquid crystal display is operated to generate an abnormal alarm.

  The preferred embodiment of the method of the present invention has been described above, but any modification can be freely made as long as it conforms to the gist of the present invention.

10 Control unit
11 Burner (combustion section)
12 Gas solenoid valve
13 Gas proportional valve
14 Fan motor
15 Speed sensor
16 Feed water temperature sensor
17 Water volume sensor
18 Hot water temperature sensor
19 Exhaust port
21 heat exchanger
31 Secondary gas pressure sensor
32 Combustion chamber pressure sensor

Claims (3)

Fuel gas from a gas proportional valve, which is an electric flow control valve, and air blown from an electric fan motor are supplied to the combustion section, and the required amount of heat required from time to time for combustion in the combustion section A combustion control method for a combustion device to obtain
In order to obtain the air volume of the blown air necessary to satisfy the required heat quantity, according to a predetermined relational expression or relation table, the fan motor is set at a predetermined applied voltage and a predetermined drive current so as to have a predetermined rotational speed. When the electric power is driven, an actual driving current that is a value of a driving current actually applied to the fan motor is detected, and a predetermined relational expression when normal combustion is performed in the combustion section is performed. Or, based on the relationship table, obtain the air volume equivalent heat quantity that should be originally obtained at the time of the actual drive current value detected at that time;
When the differential pressure between the secondary gas pressure that is the pressure of the fuel gas supplied to the combustion section and the combustion chamber pressure that is the pressure in the combustion chamber is detected, and normal combustion is being performed in the combustion section A heat amount corresponding to the differential pressure at that time is obtained as a differential pressure equivalent heat amount based on a predetermined relational expression or relationship table of
When the difference between the obtained differential pressure equivalent heat quantity and the air quantity equivalent heat quantity is detected and the difference becomes equal to or larger than a predetermined magnitude, the drive current to the flow control valve is reduced to reduce the drive current to the combustion section. Reducing the amount of fuel gas supplied or shutting off the fuel gas supply;
A combustion control method characterized by the above. In the fuel gas supply cutoff, the state in which the difference between the heat corresponding to the differential pressure and the heat equivalent to the air flow remains at the predetermined magnitude or more even when the supply amount of the fuel gas is decreased. What to do if you have more
The combustion control method according to claim 1. When the fuel gas supply is cut off, the visual or audible or visual and audible abnormality alarm means is activated;
The combustion control method according to claim 1.

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