JPH03142355A - Oxygen concentration detector - Google Patents

Abstract

PURPOSE:To prevent the erroneous decision of the oxygen concn. detector by the oxygen concn. of the ion current of a flame at the moment when a combustion rate changes by constituting the detector in such a manner that the detection of the oxygen concn. is not executed for the specified time from the moment when the combustion rate changes. CONSTITUTION:A microcomputer 1 has a means for detecting the time of the transient change via an ion current and a means for stopping the operation to detect the ion current for a prescribed period of time by receiving the signal from this detecting mean. The microcomputer is inputted with various kinds of control signals 2 and controls a relay 3 by output signals to control the form and rate of combustion. The signal 4 for the ion current of the flame is inputted to the microcomputer 1 and is used for the detection of the oxygen concn. A timer is held in the microcomputer 1 so that the detection of the oxygen concn. is not executed for the specified period of time from the moment when the combustion rate changes in the program of the timer.

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 ion current value of the flame according to the oxygen concentration, constantly compares it with the measured ion current value of the flame, and when the latter becomes smaller than the former, the oxygen concentration It is now judged as "decreasing."

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 is a problem in that the oxygen concentration detection device makes a false determination at the moment when the amount of combustion in the combustor changes. 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, this will be explained in more detail with reference to FIG.

The 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 (a). tB) is the measurement timing of the flame ion current for determining the flame ion current value according to the oxygen concentration, and the flame ion current is measured at one time point (b). (
C) is the timing for monitoring the decrease in oxygen concentration, and the decrease in oxygen concentration is monitored at time 9 (b). (DJ is the state of the combustion amount of the combustor, and there are two states: high combustion amount and low combustion amount.The ionic current of the flame changes depending on the combustion amount. Corrections are being made to the values.However.

The change in flame ion current 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 for a while at that amount, the ion current of the flame will have 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 disclosed 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 one ignition is stabilized, and the ion current detection operation is performed only once at the time of one ignition. or,
There was a problem in that incorrect determinations could occur due to changes in the ion current when the amount of combustion changed.

The present invention has been made in view of the above points, and in order to prevent the oxygen concentration detection mechanism 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.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a timing chart for explaining the present invention, in which the timing (C) for monitoring oxygen concentration is shown.
is carried out after the flame ion current measurement at the timing (B) of the flame ion current measurement (b). However, if the amount of combustion changes, then for a certain period of time 9 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 amount of combustion changes by about 75 degrees at a time.

Furthermore, the oxygen concentration does not drop rapidly within a few minutes. Therefore, it is acceptable for the performance of the oxygen concentration detection device to stop monitoring the oxygen concentration for about one minute from the moment the combustion amount changes. 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 to the microcomputer, 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 l 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 mentioned 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. Misjudgments by the detection device can be prevented. This has a great practical effect.

[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 an 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 to monitor oxygen concentration drop, D.
... Burning amount status of the combustor, 49 burners... Time l...
・Microcomputer, 2...Various control signals,
3... Relay, 4... Flame ion current signal

Claims (1)

[Claims] An oxygen concentration detection device that detects the oxygen concentration by detecting the ionic current of a flame includes means for detecting transient changes in combustion amount via the ionic current, and detecting the ionic current in response to a signal from the detecting means. An oxygen concentration detection device comprising: means for stopping operation for a predetermined period of time.