JPS62147216A - Combustion sensing device - Google Patents

Abstract

PURPOSE:To facilitate an air fuel ratio control and make a fast ignition sensing response by providing the first sensing circuit for sensing an impedance between the first flame holes and the second flame holes, the second sensing circuit for sensing an impedance between an electrode and the second flame holes and a combustion sensing circuit for calculating each of the outputs from the first sensing circuit and the second sensing circuit. CONSTITUTION:When flame holes are cold, the fuel is ignited, and when the flame is placed out of the second flame holes 11, a decreased impedance between an electrode 14 and second flame holes is detected by a first sensing circuit 19. When the flame holes are heated and the flame is present between the first flame holes 9 and the second flame holes 11, a decreased impedance between them is detected by the second sensing circuit 20, and whether the flame is positioned at the downstream side or upstream side is discriminated by the combustion sensing circuit 21 so as to perform a more accurate sensing of an air fuel ratio. Thus, it is possible to get an ignition signal of which raising is fast and of which state is continuous and stable.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an oil or gas combustion detection device.

2. Description of the Related Art A conventional combustion detection device of this type, as shown in the oil combustion machine in FIG. a fan 6 that sends vaporized gas in the vaporization chamber 4 to the mixing chamber 5 and also supplies combustion air;
A first flame hole body 9 composed of a mixing plate 7 that partitions the mixing chamber 5 and a punching plate communicating with the mixing chamber 5 and having flame holes 8.
, a cap 10 , and a first flame hole body 9 for the mixing chamber 5
A second flame hole body 11 made of a wire mesh located downstream from the first flame hole body 9 and having a certain distance from the first flame hole body 9; A terminal 12 electrically connected to the flame hole body 11 etc., a frame rod 14 insulated from them by an insulator 13, and a frame rod 14.
A voltage 15 is applied between the frame rod 14 and the terminal 12.
The impedance change of the flame formed between the flame rod body 11 and the second flame hole body 11 is detected as a change in the flame rod current 11, and the current is converted into a detection voltage VT, which is compared with the set potential vs by a comparator 16, and its output V It is composed of a detection circuit 17 that detects combustion by using Ta.

(For example, Japanese Unexamined Patent Publication No. 57-66519) Problems to be Solved by the Invention However, with the above configuration, the current value is weak and susceptible to noise, and when the combustion amount is reduced to about 1/3, the current value becomes even weaker. At the same time, changes in the air-fuel ratio become less likely to appear, making air-fuel ratio control difficult.

Furthermore, in recent years, all primary premix combustion has been attracting attention in order to reduce NOx etc. in combustion exhaust gas, but in that case, the flame is on the surface of the first flame hole body 9 or the second flame hole body 11. Since the flame rod burns in close contact with the flame rod, there is a problem in that the flame rod current If completely stops flowing.

Therefore, as a new attempt, as shown in FIG. Change in impedance between the flame hole body 9 and the second flame hole body 11? A device that detects and detects combustion has been considered.

With this configuration, the entire area of the first flame hole body 9 and the second flame hole body 11 can be used as a sensor for detecting impedance change,
Furthermore, whereas the flame rod in FIG. 7 is installed in an open space, in this configuration a kind of combustion chamber is formed between the first flame hole body 9 and the second flame hole body 11. Therefore, even when the combustion amount is reduced or when the flame is attached to the surface of the first flame hole body 9 or the second flame hole body 11 and burned, a certain amount of strange ions are present. Therefore, it was found that an extremely large current can be obtained compared to the frame rod shown in FIG.

However, in the configuration shown in FIG. 7, if the flame hole is ignited when it is cold, the flame will flow to the second flame hole body 11 until the flame hole warms up.
Since it is formed outside the flame hole body 9, it takes some time for the current to rise, which poses a problem when applied to a combustion machine that requires quick ignition detection. A certain kind of combustion chamber is formed between the flame hole bodies 11, and the flame is inside and oscillates, causing fluctuations in the current, so it is not suitable when it is necessary to accurately determine the air-fuel ratio. It had some problems.

The present invention solves all of these problems, and aims to realize a combustion detection device that can control the air-fuel ratio even when the combustion amount is reduced or in full primary premix combustion, and has a quick ignition detection response. do.

Means for Solving the Problems In order to solve the problems described above, the combustion detection device of the present invention has the following features:
A first flame hole body is created by combining the structure of the electrode having the same function as the flame rod explained in FIG. 7 and the first flame hole body and the second flame hole body explained in FIG. 8. a first detection circuit that detects the impedance between the electrode and the second flame hole body; a second detection circuit that detects the impedance between the electrode and the second flame hole body; The combustion detection circuit includes a combustion detection circuit that calculates the output of each of the detection circuits.

Function: With the above configuration, the present invention ignites when the flame hole body is cold, and reduces the impedance between the electrode and the second flame hole body while the flame is outside the second flame hole body. The first detection circuit detects the flame, and when the flame hole warms up and the flame is present between the first flame hole body and the second flame hole body, the second detection circuit detects a decrease in impedance between the first flame hole body and the second flame hole body. Precise air-fuel ratio detection is performed by using a combustion detection circuit to determine whether the flame is on the downstream side or on the flow side of the second flame hole body.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In FIG. 1, the parts with the same numbers as those in FIG. 9 and the second flame hole body 11; a second detection circuit 20 that detects the impedance between the second flame hole body 11 and the electrode 14; The combustion detection circuit 21 calculates the outputs of the first detection circuit 19 and the second detection circuit to generate a combustion detection output. an ignition detection circuit 24 consisting of a sum/comparison calculation circuit 22 that compares the sum with the output of 20 or the output of both and outputs the larger one; and a comparison circuit 23 that compares the output with a set value v81; It is composed of an air-fuel ratio detection function 27 for fuel, which includes a difference calculation circuit 25 that outputs the difference between the output of the circuit 19 and the output of the second detection circuit 20, and a comparison circuit 26 that compares the output with a set value v112. There is.

Regarding the ignition detection function of the combustion detection circuit 21 in the configuration described above, if the flame hole is cold at the time of ignition, the second
As shown in Figure a, the flame cannot attach to the first flame hole body 9 and is formed outside the second flame hole body 11. Therefore, the impedance between the first flame hole body 9 and the second flame hole body 11 is extremely high, and the current 1y detected by the first detection circuit 19 is completely zero. Second
The impedance between the flame hole bodies 11 is low, and the current f detected by the second detection circuit 20 rises at the same time as ignition. After some time has passed, the flame warms up the flame hole, and the flame attaches to the first flame hole body 9 as shown in Figure 2, and the flame spreads between the first flame hole body 9 and the second flame hole body 11. A flame is formed on the very surface of the second flame hole body 11. Therefore, the impedance between the first flame hole body 9 and the second flame hole body 11 becomes lower, Ig increases, and the electrode 14 and the second flame hole body 1
The impedance between 1 and 1 becomes high and If decreases. The state is shown in FIG. The vertical axis shows the current ■, and the horizontal axis shows the elapsed time tl.As can be seen from this figure, although Il alone has a good rise, it has the problem that the value decreases to a minute value as the elapsed time increases. Although a large current can be obtained, there is a problem that there is a delay in td at the rise, but the composite value I g + 11 compensates for each of the drawbacks, and the rise and rise are fast and a large current value can be obtained, and all problems are solved. resolved. The sum/comparison calculation circuit 22 fulfills this role.
It is. In this example, I g + I 1,
Almost the same performance can be obtained by comparing Ig and I (and using the larger value of the two).

Next, the air-fuel ratio detection function of the combustion detection circuit 21 will be explained with reference to FIGS. 2 and 4. When Pa is less than 1, there is a lack of air and the flame is at an intermediate point between a and b in FIG. become a state. When the air increases and P becomes larger than 1,
Since the air supply is sufficient, the flame enters the state shown in Figure 2 and burns in close contact with the first flame hole body 9. Therefore, Ig increases and 11 becomes all zero. Furthermore, as Pa increases, the jetting speed of the air-fuel mixture increases, and the first flame hole body 9 is cooled, so that the flame is less likely to adhere to the first flame hole body 9.
It gradually approaches the second flame hole body 11 side. Therefore I
y decreases after reaching a peak. In the region where Ig decreases from its peak, the flame spreads between the first flame hole body 9 and the second flame hole body 11.
Since the Ig is located in the space formed by the flame and a collision phenomenon with the second flame hole also occurs, the Ig fluctuates widely and it is difficult to obtain an accurate value. When Pa further increases, the flame cannot attach to the first flame hole body 9, and the flame transfers and adheres to the second flame hole body 11 as shown in FIG. 2a.

Therefore, since the flame comes out on the surface of the second flame hole body 11, If increases, Ig further decreases, and finally the magnitude relationship is reversed at the Pa1 point. Reversal point Pa1 marked with
can be rephrased as the point at which the flame exits from the inside to the outside of the second flame hole body 11, since the configuration is such that the exit of the flame is detected by both a decrease in Ig and an increase in If. Inversion points) P and l are obtained in an extremely stable state. Moreover, when the combustion amount changes, the peak point of Ig changes, but the change in the reversal point Pa1 is small, so Pa1'! By monitoring r, the air-fuel ratio Pa can be determined and precise air-fuel ratio control becomes possible. The difference calculation circuit 25 and the comparison circuit 26 monitor Pa1, and if the difference is zero, the air-fuel ratio will be Pa1, and if the difference is, for example, △■, the air-fuel ratio will be FiPa2VC. It is also possible to move the monitoring of the air-fuel ratio to some extent.

Ig+I used for ignition detection (is the air-fuel ratio P as shown in the figure)
It can be seen that large values are obtained over a wide range of a.

Next, another embodiment of the present invention will be described using FIG. Some combustion machines do not require air-fuel ratio detection and only require ignition detection. In that case, not only the air to fuel ratio detection circuit 27 shown in FIG. 1 becomes unnecessary, but also the sum/comparison calculation circuit 22 is eliminated so that the sum output can be obtained on the combustion machine main body side. Is possible.

The difference from the embodiment shown in FIG. 1 is that the electrode 14 is
By attaching it to the end 200 of the vaporizer 2 instead of attaching it to the terminal, the electrode 14 and the first flame hole body 9 are at the same potential, and the current flowing through the terminal 12 is connected to the first flame hole body 9 and the second flame hole body 9.
This is the sum of the current flowing between the flame hole body 11 and the current flowing between the flame hole body 11 (j14 and the second flame hole body 11).

Another embodiment having the same purpose will be described with reference to FIG. The difference from the embodiment shown in FIG. 1 is that the electrode 14 is eliminated and the end 180 of the cap 1o is configured to extend downward and touch the flame formed on the surface of the second flame hole body, and the cap 10 and the second flame hole body 9 are configured so that the cap end 180 and the first flame hole body 9 are at the same potential. This is the sum of the current flowing between the second flame hole body 11 and the current flowing between the cap end 180 and the second flame hole body 11.

Incidentally, in the embodiment described above, it is natural that the oil pump a, the fan 6, etc. are not required if the oil burner is used, and the present invention is not limited to this example.

Effects of the Invention As described above, the combustion detection device of the present invention includes a first flame hole body, a second flame hole body, and an electrode, and a flame hole body between the first flame hole body and the second flame hole body. a first detection circuit that detects impedance;
a second detection circuit that detects the impedance between N, @ and the second flame hole body; and a combustion detection circuit that calculates the outputs of the first detection circuit and the second detection circuit to generate a combustion detection output. While the flame is inside the second flame hole body, the first detection circuit detects a decrease in impedance between the first flame hole body and the second flame hole body, and the flame is detected by the first detection circuit. While it is outside the second flame hole body, the second detection circuit can detect the decrease in impedance between the second flame hole body and the electrode, and the output of the rain detection circuit can be calculated by the combustion detection circuit. , has the following characteristics.

(2) Regardless of whether the flame is formed inside or outside the second flame hole body due to changes in the flame hole temperature or air-fuel ratio, a large ignition signal can be obtained and excellent noise resistance is achieved.

■ If you ignite when the flame hole is cold, the flame will not be able to attach to the first flame hole body, but will initially form on the outside of the second flame hole body, and the temperature of the flame hole will rise. The flame transfers and attaches to the first flame hole body, but by calculation in the combustion detection circuit, the output of the second detection circuit is initially set, and after the flame transfers and adheres to the first flame hole body, the output of the second detection circuit is
It is possible to use the output of the detection circuit, and it is possible to obtain a continuous and stable ignition detection signal with a fast rising edge of the signal.

■ When the air-fuel ratio is small, the injection speed of the mixture is slow and the temperature of the flame hole is high, so the flame is inside the second flame hole body, and when the air-fuel ratio increases, the injection speed of the mixture becomes faster and the flame moves downstream. The first flame hole body is cooled by the jet of the air-fuel mixture and becomes easier to move away from the first flame hole body, so a flame is formed on the outside of the second flame hole body. Since the air-fuel ratio that causes the movement of the flame is constant, the combustion detection circuit determines the difference between the output of the first detection circuit and the output of the second detection circuit, 1iLfff: The fuel ratio can be monitored.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a combustion detection device according to an embodiment of the present invention, and FIG. 2 is a diagram of the state of flame formation in the flame hole in the same device.
@ Figure 3 is a standing characteristic diagram of the same device, Figure 4 is a steady-state characteristic diagram of the same device, Figure 5 is a configuration diagram of a frame rod attachment part in another embodiment of the present invention, and Figure 6 is a diagram of the frame rod attachment part in another embodiment of the present invention. FIG. 7 is a block diagram of a cap portion in another embodiment, FIG. 7 is a block diagram of a conventional combustion detection device, and FIG. 8 is a block diagram of another conventional combustion detection device. 5... Mixing chamber, 9... First flame hole body,
DESCRIPTION OF SYMBOLS 11... Second flame hole body, 14... Electrode, 18... Insulator, 19... First detection circuit, 20... ...Second detection circuit, 21...
... Combustion detection circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 5
Figure 6 S N Rizuka
So--Satoru H- Ward! regret

Claims (3)

[Claims] (1) A mixing chamber for mixing fuel and combustion air, a first flame hole body communicating with the mixing chamber, and a flame hole body located downstream of the first flame hole body with respect to the mixing chamber. a second flame hole body provided at a certain distance from the first flame hole body, an electrode provided so as to be in contact with the flame formed by the second flame hole body, and the first flame hole body. an insulator that electrically insulates between the flame hole body and the second flame hole body and between the electrode and the second flame hole body; a first detection circuit that detects the impedance between the flame hole body, a second detection circuit that detects the impedance between the electrode and the second flame hole body, the first detection circuit and the second flame hole body; A combustion detection device comprising a combustion detection circuit that calculates the output of each of the detection circuits and generates a combustion detection output. (2) The combustion detection circuit performs calculation to compare the sum of the output of the first detection circuit and the output of the second detection circuit, or to output the larger one by comparing the outputs of both, and outputs the larger one as an ignition detection signal. Combustion detection device according to item 1. (3) The combustion detection device according to claim 1, wherein the combustion detection circuit performs calculation to output the difference between the first detection circuit output and the second detection circuit output, and outputs the difference between the first detection circuit output and the second detection circuit output as an air to fuel ratio signal. .