JPH0465341B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an oxygen concentration detection device that detects oxygen concentration through the ionic current of a flame.

Conventionally, this type of oxygen concentration detection device sets the flame ion current value according to the oxygen concentration, constantly compares it with the measured flame ion current value, and when the latter becomes smaller than the former, the oxygen concentration ``Decrease''.

However, the ion current of the flame changes with changes in the amount of combustion in the combustor, and also pulsates significantly at the moment of change. Therefore, there was a problem in that the oxygen concentration detection device made a false determination at the moment the amount of combustion in the combustor changed. In order to prevent such misjudgments, conventionally, the ion current value of the flame, which indicates a decrease in oxygen concentration, has been set low.

That is, to explain more specifically with reference to FIG.
This figure is a timing chart of a conventional oxygen concentration detection device, and in the figure, A indicates whether or not the combustor is burning. Assume that the combustor starts combustion at time point A. B is the measurement timing of the flame ionic current for determining the flame ionic current value according to the oxygen concentration, and the flame ionic current is measured at time point B. C is the timing for monitoring the decrease in oxygen concentration, and the decrease in oxygen concentration is monitored at time point C. D is the combustion amount state of the combustor, and there are two states: high combustion amount and low combustion amount. Since the ion current of the flame changes depending on the amount of combustion, the ion current value of the flame has conventionally been corrected based on the amount of combustion. However, the change in the ion current of the flame at the moment when the amount of combustion changes is large and does not necessarily correspond to the amount of combustion. Even if the amount of combustion changes, if combustion continues at that amount for a while,
The ion current of the flame has a value corresponding to the amount of combustion. Therefore, in the past, the oxygen concentration detection device sometimes made an erroneous determination at the moment the combustion amount changed.

Incidentally, there is a conventional oxygen concentration detection device as shown in Japanese Patent Application Laid-Open No. 57-2928.

However, in this configuration, the detection operation is not performed at the time of startup until the ion current at the time of ignition is stabilized, and the ion current detection operation is performed only once at the time of ignition. Additionally, there is a problem that erroneous determinations may occur due to changes in the ion current when the amount of combustion changes.

The present invention was made in view of the following points. In order to prevent the oxygen concentration detection device from making a false judgment when the combustion amount changes excessively, the oxygen concentration is not detected for a certain period of time from the moment the combustion amount changes. This problem is solved by preventing the operation from occurring.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 2 and 3.

FIG. 2 is a timing chart for explaining the present invention, and in the same figure, timing C for monitoring the oxygen concentration is carried out after the measurement of the flame ion current at time RO of timing B of flame ion current measurement. . However, if the combustion amount changes, for a certain period of time from the moment of the change, e.g.
In a combustor of about 3000Kcal/hour, for 1 minute,
Do not monitor oxygen concentration.

Generally, when a combustor is used in a kerosene stove, the degree of change in combustion amount is about 1 time/5 minutes.
Furthermore, the oxygen concentration does not drop rapidly within a few minutes. Therefore, from the moment the combustion amount changes, 1
Even if oxygen concentration monitoring is stopped for about a minute, there is no problem with the performance of the oxygen concentration detection device. The present invention has been made with attention to this point.

FIG. 3 is an electric circuit diagram according to an embodiment of the present invention, in which 1 indicates a means for detecting transient changes in combustion amount via an ion current, and a means for receiving a signal from this detecting means. The microcomputer is equipped with means for stopping the ion current detection operation for a predetermined period of time, and various control signals 2 are inputted thereto, and the combustion mode and combustion amount are controlled by controlling the relay 3 based on the output signals. The flame ion current signal 4 is input to the microcomputer 1 and used to detect the oxygen concentration. The microcomputer 1 has an internal timer, and its program is such that the oxygen concentration will not be detected for a certain period of time from the moment the combustion amount changes.

As described above, the present invention is configured so that oxygen concentration detection is not performed for a certain period of time from the moment when the combustion amount changes, so that the oxygen concentration can be detected by transient changes in the ionic current of the flame at the moment when the combustion amount changes. This has the great practical effect of preventing post-determination by the detection device.

[Brief explanation of the drawing]

FIG. 1 is a timing chart of a conventional oxygen concentration detection device, FIG. 2 is a timing chart of an oxygen concentration detection device according to the present invention, and FIG. 3 is an electric circuit showing an embodiment of the oxygen concentration detection device according to the present invention. It is a diagram. A: Status of whether the combustor is burning or not, B
... Flame ion current measurement timing for determining the flame ion current value indicating a decrease in oxygen concentration, C...
...Timing for monitoring the decrease in oxygen concentration, D...State of the combustion amount of the combustor, A, B...Time, 1...Microcomputer, 2...Various control signals, 3...
...Relay, 4... Signal of flame ion current.

Claims (1)

[Claims] 1. In an oxygen concentration detection device that detects oxygen concentration by detecting an ionic current of a flame, means for detecting a transient change in combustion amount via the ionic current;
An oxygen concentration detection device comprising means for receiving a signal from the detection means and stopping an ion current detection operation for a predetermined period of time.