JPH0370911A - Combustion controller - Google Patents

Abstract

PURPOSE:To make it possible to control rapidly at a proper air excess ratio by providing a correction device which corrects feedback values based on the feedforward values during the combustion quantity is changing before the change and after it. CONSTITUTION:A combustion quantity calculation section 14 calculates combustion quantity, and in a feedforward value outputting section 15 the feedforward value WFF which corresponds to the combustion quantity is determined. Next, the excess air ratio is judged in a rate of excess air judging section 11 based on the flame temperature detected by a temperature sensor. If the judged excess air ratio is not proper, feedback value WFB is calculated according to it in a feedback value calculation section 17. This feedback value WFB is inputted to a correction calculation section 18, and it is corrected based on the feedforward value WFF that is outputted from the feedforward value outputting section 15 and the previous feedforward value W'FF that is stored in a memory 16, and the target value WS that is the addition of the correctedfeedback value W'FB and feedforward value WFF is outputted from a target value calculation section 12 to control the rotational speed of a fan motor 3 at the target value WS.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combustion control device for a forced air combustor.

(Prior Art) Conventional forced air combustors, especially all-primary air combustors in which all the air required for combustion is used as primary air and is premixed with fuel gas, have a high-temperature sensor that detects the flame temperature. The amount of combustion air is maintained at l1flll and the excess air ratio is maintained at a preferable value in accordance with the output from a combustion state detection means such as a thermistor or thermocuff pull.

(Problem to be solved by the invention) In this type of conventional device, a response delay of the combustion state detection means is unavoidable, so when the combustion amount is changed, the feedforward value corresponding to the combustion amount changes immediately. However, the feedback value calculated based on the output from the combustion state detection means does not change for a while, and the feedback value before the combustion amount changes is given, so the air waste rate can be quickly adjusted to a preferable value. r,=tsm.

The present invention solves the above-mentioned conventional problems and enables combustion@
The purpose is to provide control equipment.

(Means for solving !Ill) In order to achieve the above object, the combustion control device of the present invention calculates the feedforward value corresponding to the combustion amount and the output from the combustion state detection means. When the combustion amount changes, a correction means is provided for correcting the feedback value based on the feedforward value before and after the change.

(Function) When the combustion amount changes, the feedforward value changes corresponding to the combustion amount, but there is a response delay in the output from the combustion state detection means, and the feedback value calculated based on this output is Therefore, based on the feedforward value before and after the combustion change, for example, if the feedforward value decreases to 1/3 before and after the change, the above feedback value is changed to 1/3. The amount of combustion air is controlled by making corrections such as changing the amount of air to a certain value.

(Implementation N) I! Figure 3 shows a schematic configuration of the forced air combustor I@ according to the present invention, in which 1 is a flame hole plate having a large number of flame holes penetrating the front and back sides, 2 is a fuel supply path, 3 is a fan motor, Fuel gas and air necessary for combustion are introduced into the premixing chamber 4. 5 is a current plate, 6 is a temperature sensor (combustion state detection means) for detecting the temperature of the flame, and the fuel supply path 2 has a ratio f1.
A tsm valve 7 and a solenoid valve 8 are provided.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which the output of the temperature sensor 6 is manually inputted to the excess air ratio determining section 11 of the micro combinator IO via the thermo circuit 9, and the 7 ammotor 3 is operated by the microcomputer IO. target value calculation unit 1
The rotation speed is controlled by the output from 2 via the drive circuit 13. 14 is a combustion amount calculation unit, 15 is a feedforward value output unit that outputs a feedforward value WFF corresponding to the combustion amount, and 16 is a feedforward value output unit 1.
5, a storage section 17 stores a feedback value WF according to the output from the excess air ratio determination section 11;
A feedback value calculation unit 18 outputs a feedforward value WFF, a feedback value WFB, and a previous feedforward value W′F stored in the storage unit 1G.
This is a correction calculation unit (correction means) that inputs F and corrects the feedback value WFB.

FIG. 2 is a flowchart of operations that are repeated at predetermined time intervals. First, the combustion amount is calculated by the combustion amount calculation unit I4, and the feedforward *WFF corresponding to the fuel Ill is determined by the feedforward value output B15. Next, the excess air ratio determination unit 11 determines the air collapse ratio based on the flame temperature detected by the temperature sensor 6, and if it is not an appropriate value, the feedback value calculation unit 17 determines the feedback value WPB according to the determined value. Calculated. This feedback value WFB is input to the correction calculation unit 18, and the feedforward value WFB is output from the feedforward value output unit 15.
FF and the previous feedforward value W'FF stored in the storage unit 16, the corrected feedback value W'FB and the feedforward value WFF are corrected as W'FB to WFBXWFF/W'FF. The target value Ws obtained by adding the above is output from the target value calculating section 12, and the rotation speed of the fan motor 3 is increased by 14g1 to the target value Ws.

If it is determined that the excess air ratio has reached a proper value, the feedback value WFB will maintain the same value as the previous time.

Now, at a certain combustion amount, the feedforward value WF
F=400 Orpm, and the feedback value W
Assume that a proper excess air ratio is obtained at FB=200 Orpm. If the combustion amount is increased here and the feedforward value corresponding to the combustion amount after the change becomes WFF 1000 rp-, there is a response delay in the output of the temperature sensor 6, so the feedback value WFB is the change in the combustion amount. The same as before < WFB = 2000rpfin, which is an excessive value for the fuel mu after the change, but W'FB = WFBxWFF/W'FF = 2000
X 1000 /400G=500 (rpm), and an appropriate target value of Ws = 1500 rpm can be given, and even if the combustion amount changes, an appropriate excess air ratio can be quickly obtained.

(Effects of the Invention) The combustion control device of the present invention has the following excellent effects. That is, even if a combustion state detection means with a delayed response is used, the combustion state will not deteriorate significantly when the combustion amount changes, and the excess air ratio can be quickly controlled to an appropriate excess air ratio.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the invention i! FIG. 2 is a control block diagram, FIG. 2 is a control flowchart, and FIG. 3 is a schematic configuration diagram of a forced air combustor according to the present invention. 3...Fan motor 6...Temperature sensor (combustion state detection means) IO...Micro combiator 15...Feedforward value output section 17...Feedback value calculation section 18...Correction calculation section ( Correction means) Figure 1 Figure 3

Claims (1)

[Claims] In a system that controls the amount of combustion air based on a feedforward value corresponding to the combustion amount and a feedback value calculated according to the output from the combustion state detection means, the feedforward control is performed when the combustion amount changes, before and after the change. A combustion control device comprising a correction means for correcting a feedback value based on the value.