JPH1114049A - Gas combustion controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable detection of an ignition failure and an abnormal combustion by making a gas combustion controller have reference value computing means which outputs the flame current reference value, allowable range computing means which sets an allowable range of a given rate which recognizes a normal combustion with respect to the flame current reference value, and abnormality judgment means which includes a comparator and the like. SOLUTION: A gas combustion controller is provided with flame current detection means 3 which outputs an ion current generated from a burner flame and based on the detected flame current, abnormality judgment means 4 judges whether the combustion is normal or abnormal. This abnormality judgment means 4 includes reference value computing means 4a which outputs the flame current reference value which is the flame current at given excessive air factor at the time of an optimum air-fuel ratio which is considered as a normal combustion, and allowable range computing means 4b which sets allowable ranges above and below the flame current reference value with allowable width of given ratio which are considered as a normal combustion with respect to the flame current reference value. Then, the allowable range of the flame current reference value and the flame current reference value are compared by means of comparing means 4c. A signal is outputted as abnormal when the flame current is deviated from the allowable range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas combustion control device for controlling the combustion of gas appliances, and more particularly to a gas combustion control device capable of coping with various gases and having high accuracy even when adjusting the heating power, that is, even when the amount of combustion changes. The present invention relates to a gas combustion control device capable of coping with abnormal combustion.

[0002]

2. Description of the Related Art Flame current detecting means for outputting an ion current due to a flame of a burner as a flame current detection value, and an abnormality for discriminating a combustion abnormality of the burner based on the flame current by the flame current detecting means and outputting a signal. In a gas combustion control device including a determination unit and a combustion control unit that controls combustion based on an abnormality signal from the abnormality determination unit, a required combustion amount related to switching between gas types having different calorific values and heat power adjustment. Conventionally, to determine combustion abnormalities in response to changes in
Some of the main burners and the sub burners are provided with flame rods for detecting a flame current (for example, see Japanese Patent Application Laid-Open No. 59-1).
No. 89217).

In this gas combustion control apparatus, a main burner capable of adjusting the thermal power and an auxiliary burner having a fixed combustion amount are provided for comparison, and a flame rod for detecting a flame current is provided for each of them.
By adjusting and setting the circuit constant so that the current difference between the two corresponds to the air-fuel ratio of the combustion gas, it is possible to determine the burner combustion abnormality according to the gas type and regardless of the change in the required combustion amount. It is possible to do it.

[0004]

However, the above-described gas combustion control device requires a flame rod for detecting a flame current in each of the main burner and the sub-burner. In order to cope with the variation of the flame current characteristic of each frame rod due to the assembly error or the like, it is necessary to adjust and set the circuit constant according to the flame current characteristic. Further, since the flame current characteristic may change during use of the combustor, it is difficult to determine the burner combustion abnormality with high accuracy. Accordingly, an object of the present invention is to provide a gas combustion control device capable of detecting any combustion abnormality when ignition is not performed or combustion is abnormal even if ignition is performed.

[0005]

In order to solve the above-mentioned problems, a reference value calculating means for outputting a flame current reference value which is a flame current by a flame at an optimum air-fuel ratio for normal combustion, and a reference value calculating means. Means for setting an allowable range for the flame current reference value with an allowable width of a predetermined ratio for normal combustion with respect to the flame current reference value by the means; The gas combustion control device is constituted by abnormality determination means comprising a flame current detection value and a comparison means for outputting a signal as a combustion abnormality when the flame current is out of the allowable range. Preferably, a misfire reference value output means for outputting a misfire reference value set to be smaller than the minimum value of the flame current reference value by the permissible range calculating means, and The gas combustion control device is constituted by abnormality determination means including a comparison means for determining misfire by comparing with.

[0006]

The reference value calculation means outputs a flame current reference value which is a flame current due to the flame at a predetermined air-fuel ratio at which normal combustion is performed. A permissible range is set above and below the flame current reference value with a permissible width, and a comparison means compares the permissible range with the flame current detection value detected by the flame current detection means. By output, the abnormality determination means determines the combustion abnormality of the burner, and the combustion control means controls the combustion based on the abnormality signal from the abnormality determination means. Further, the misfire reference value setting means sets the misfire reference value in the comparison means, and when the flame current detection value is larger than the misfire reference value, misfire can also be determined by the comparison means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a functional block diagram of the gas combustion control device according to the present invention, FIG. 2 is a flame current reference value characteristic diagram, FIG. 3 is a flame current characteristic diagram with respect to excess air ratio, and FIG. 4 is a combustion control processing procedure diagram.

In FIG. 1, a gas combustion control apparatus A includes a flame current detection means for outputting an ion current due to a flame of a burner (not shown) as a flame current detection value, in addition to a gas type switching means 1 and a required combustion amount calculation means 2. Means 3 and the flame current detecting means 3
Abnormality determination means 4 for determining an abnormal combustion based on the flame current caused by the above, a combustion control means 5 for controlling combustion based on an abnormality signal from the abnormality determination means 4, a time measuring means 6, and the like.

The gas type switching means 1 outputs gas type specifying information corresponding to a gas type selected by an input operation from a plurality of gas types such as 13A and 4C-2 in order to specify the type of the supplied gas. . The gas type specifying information enables the required combustion amount calculation means 2 and the abnormality determination means 4 to perform control processing according to the calorific value of the supplied gas.

The required combustion amount calculating means 2 receives an incoming water temperature 2a, a set temperature 2b, a flow rate 2c, and a hot water temperature 2d from a sensor or an operation panel (not shown), and combines the information with the gas type identification information of the gas type switching means 1. A combustion amount corresponding to a request for tapping or the like is calculated, and combustion target information is sent to the abnormality determination means 4 and the combustion control means 5.

The abnormality determining means 4 includes a reference value calculating means 4a for outputting a flame current reference value which is a flame current due to a flame at a predetermined excess air ratio at an optimum air-fuel ratio at which normal combustion is performed, and a reference value calculating means 4a. Range calculating means 4b for setting an allowable range above and below the flame current reference value with an allowable range of a predetermined ratio for normal combustion with respect to the flame current reference value, and an allowance of the flame current reference value by the allowable range calculation means 4b. A comparison means for comparing the range with the flame current detection value and outputting a signal indicating abnormal combustion when the flame current is out of the permissible range.

Further, the abnormality determining means 4 includes a short-circuit reference value output means 4d for monitoring the short-circuit of the flame current detecting means 3,
The short circuit reference value output means 4d outputs the short circuit reference value to the comparison means 4c. The short-circuit reference value is set to be larger than the maximum value of the flame current reference value determined by the capacity of the water heater.

The flame current reference value of the reference value calculating means 4a is a flame current characteristic at the time of the optimum air-fuel ratio, as shown by a flame current reference value I on the vertical axis corresponding to the combustion amount Q on the horizontal axis in FIG.
The characteristics are different for each gas type. 11 indicates a characteristic relating to each gas type of 4c-2 and 12 indicates a characteristic relating to each gas type of 13A. This flame current reference value is calculated by the reference value calculation means 4a in accordance with the gas type and the required combustion amount.

Next, the flame current characteristic with respect to the air-fuel ratio will be described by taking the flame current characteristic with respect to the excess air ratio as an example.

The allowable range of the flame current reference value by the allowable range calculating means 4b is as follows. When the specific current is set with the excess air ratio on the horizontal axis and the flame current reference value on the vertical axis as 100%, the air supply is insufficient. For example, the specific current is in a range of 90% or more, that is, an allowable width 10 from the flame current reference value, corresponding to the range in which the normal combustion region except for the incomplete combustion region and the flame lift due to excessive air supply is excluded. % Or less.

The combustion control means 5 controls the driving of the igniter 5a, the blower 5b, and the gas control valve 5c based on information from the required combustion amount calculating means 2, the abnormality determining means 4 and the timing means 6.

The operation of the gas combustion control device A having the above configuration will be described below.

In FIG. 4, a combustion control processing step S1 is started by operating a hot water tap of a water heater (not shown), and in a combustion command processing step S2, the igniter 5a, the blower 5b, and the gas control valve 5c of FIG. Is driven.

In this combustion command processing step S2, FIG.
Water temperature 2a, set temperature 2b, flow rate 2c, tap water temperature 2
Based on d and the information of the gas type switching means 1 set in advance, the combustion control means 5 makes the ignition device 5a, the blower 5b, The gas control valve 5c is controlled.

At the start of ignition, the combustion control means 5
However, the residual gas is discharged by the blower 5b, and subsequently, the igniter 5a and the gas control valve 5c are driven, the timing means 6 is activated in the next timing start step S3, and the flame current is detected in the flame current input step S4. The flame current of the means 3 is read.

The abnormality judging step S5 comprises an abnormality judging means 4
The comparison of the flame current of the flame current detecting means 3 for the flame current allowable range check corresponding to the required combustion amount by the reference value calculating means 4a and the allowable range calculating means 4b and the short-circuit check by the short-circuit reference value output means 4d. Comparison means 4c
Done by

If the combustion is normal after ignition, the specific current for the flame current is in the range of 90% to 100%, so that the abnormality determination means 4 issues a normal signal and is sent to the combustion control means 5 for combustion. It is repeated from the command processing step S2. At this time, the combustion control means 5 corresponds to the next required combustion amount sent from the required combustion amount calculation means 2.

When the ignition is not performed or when the combustion is abnormal even if the ignition is performed, the abnormality determining means 4 sends an abnormal signal to the combustion controlling means 5 and obtains from the time measuring means 6 in the time elapse determining step S6. If the elapsed time is less than the predetermined time sufficient to confirm that the abnormality cannot be recovered, the process is repeated from the flame current input step S4.

When the abnormal state continues for the above-mentioned predetermined time, in the combustion stop command output step S7, the combustion control means 5 stops the igniter 5a, the blower 5b and the gas control valve 5c to reach the END step S8, and the combustion of the gas is stopped. It is safely stopped by the gas combustion control device A.

By providing the misjudgment means 4 with a misfire reference value output means serving as a reference for judging a misfire connected to the comparing means 4c, it is possible to quickly cope with a misfire. The misfire reference value is set smaller than the minimum possible value of the flame current reference value. The specific control procedure can be performed by performing a misfire determination between the abnormality determination step S5 and the time elapsed determination step S6 in FIG. 4 and transferring the control to the combustion stop command output step S7 when a misfire occurs.

[0026]

As described above, according to the present invention, the reference value calculating means for outputting the flame current reference value for normal combustion and the allowable range of the predetermined ratio for normal combustion for the flame current reference value are set. Since the gas combustion control device is configured by connecting the abnormality determining means including the allowable range calculating means to be set and the comparing means to the combustion controlling means, the flame current corresponding to the normal combustion is obtained by the reference value calculating means and the allowable range calculating means. An allowable range is set, and based on the allowable range, the flame current detection value is compared and determined, and the combustion is controlled.

Therefore, the gas combustion control device according to the present invention can deal with abnormalities in combustion with high accuracy regardless of the type of gas and regardless of a change in the amount of combustion, thereby ensuring the safety of combustion. be able to. In particular, since not only the flame current reference value but also the misfire reference value is compared with the flame current detection value, it is possible to detect any combustion abnormality when the ignition is not performed or when the combustion is abnormal even if the ignition is performed.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a gas combustion control device according to the present invention.

FIG. 2 is a characteristic diagram of a flame current reference value.

FIG. 3 is a diagram showing a flame current characteristic with respect to an excess air ratio.

FIG. 4 is a flowchart of a combustion control process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Gas type switching means 2 ... Required combustion amount calculation means 3 ... Flame current detection means 4 ... Abnormality determination means 4a ... Reference value calculation means 4b ... Allowable range calculation means 4c ... Comparison means 5 ... Combustion control means A ... Gas combustion control apparatus

Claims (1)

[Claims] 1. A flame current detection means for outputting an ion current due to a flame of a burner as a flame current detection value, and an abnormality for judging a combustion abnormality of the burner based on the flame current by the flame current detection means and outputting a signal. A gas combustion control device comprising: a determination unit; and a combustion control unit that controls combustion based on an abnormality signal from the abnormality determination unit. A reference value calculating means for outputting a flame current reference value which is a flame current due to the flame at the time of the fuel ratio; and a flame current reference value obtained by the reference value calculating means. Tolerance range calculating means for setting a tolerance range; and a misfire reference value output for outputting a misfire reference value set to be smaller than the minimum value of the flame current reference value by the tolerance range calculation means. And a comparing means for comparing the flame current reference value and the misfire reference value with the flame current detection value to determine misfire.