JPS61128027A - Abnormal condition sensing circuit for combustion control device - Google Patents

Abstract

PURPOSE:To detect an abnormal frequency and prevent an accident such as an incomplete combustion or the like by a method wherein in a circuit for a combustion control device, a duty variable pulse is inputted in it and compared with an expected frequency range which is acknowledged as a normal condition and if it is out of the range, an abnormal signal is outputted. CONSTITUTION:When a fuel supplying volume signal circuit So corresponding to each of the burning capacity is applied from a main control circuit 4 to a sproportional valve during circuit 5, a duty variable pulse Sp which is made as a duty pulse corresponding to the fuel supplying volume is produced at the output of the proportional valve during circuit 5. This duty variable pulse Sp is inputted to the proportional valve 6 to control the same, an effective opening area of the fuel supplying passage is controlled in such a way as it may correspond to the duty value at the time and thus the fuel supplying volume is controlled. This duty variable pulse Sp is inputted to the frequency abnormal condition sensing circuit 8 to generate the signal.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a combustion control device for various combustion equipment that heats flowing water, such as a gas instantaneous water heater. The present invention relates to an abnormality detection circuit that can be used incidentally to a type of device that adjusts the amount of fuel supplied to a section.

(Prior Art) Nowadays, this type of combustion control device operates under the commands of a main control circuit 4, which is generally composed of a microcomputer, as shown in FIG.

That is, the feed water temperature sensor 1. Water heater sensor 2. The main control circuit 4 determines the amount of combustion required at any given time based on the information obtained from the water supply amount sensor 3 and the set temperature information from the temperature setting operation section 7 operated by the user to set the desired hot water temperature. is calculated, and the amount of fuel supplied, such as the amount of gas, is calculated accordingly.

On the other hand, recently, such adjustment of the fuel supply amount has been increasingly performed using a proportional valve 6 controlled by a variable duty pulse.

That is, as shown in FIG. 2, the fuel supply amount calculated by the main control circuit 4 at any given time is first given to the proportional valve drive circuit 5 as a fuel supply amount signal So in an appropriate form. The proportional valve drive circuit 5 that receives the signal So converts the signal So into a duty pulse signal S corresponding to its content.
P, thereby controlling the proportional valve 6 and adjusting its opening degree.

For example, when the required amount of fuel supply increases,
The proportional valve drive circuit 5 functions to increase the duty of the variable duty pulse Sp, and increases the opening degree of the proportional valve 6 by that amount, so that more fuel is supplied to the combustion section (not shown), and vice versa. When the required combustion amount decreases, the duty of the variable duty pulse Sp is lowered, the opening of the proportional valve 6 is narrowed, and the amount of fuel supplied to the combustion section is reduced.

<Problems to be Solved by the Invention> However, with the conventional combustion control device configuration as described above, it is difficult to deal with abnormalities in the control signal system of the proportional valve 6, which directly regulates the amount of fuel supplied to the combustion section. This cannot be detected because there is an abnormality in the arithmetic system of the main control circuit 4, and the content of the fuel supply amount signal So is out of order. If the duty or frequency of the pulse Sp falls into an abnormal range, or if there is an abnormality in the proportional valve drive circuit 5 itself, the duty or frequency of the variable duty pulse Sp generated by it falls into an abnormal range. Even if it does, it cannot be detected.

The most troublesome situation is when such a variable duty pulse Sp with an abnormal frequency is generated but within the response range of the proportional valve 6.

That is, under normal combustion mode, the frequency of the variable duty pulse Sp varies as the combustion amount required changes from time to time, but its upper and lower limits are as follows.
Therefore, the amount of fuel supplied does not fluctuate abnormally large, but due to some factor an abnormality occurs in the signal system as mentioned above, and eventually Even if an abnormality occurs in the frequency of the variable duty pulse Sp that is outside the predetermined frequency band, if it is within the response range of the proportional valve 6, the proportional valve will respond to the command of the abnormal signal. 1. For example, it is possible that an abnormally large amount of fuel is supplied to the combustion section. The result is.

This may cause not only a drastic change in hot water temperature but also a serious accident due to incomplete combustion ring 1.

The present invention has been developed in view of these conventional problems.

This was done with the aim of providing a device that can detect frequency abnormalities in variable duty pulses.

<Means to solve the problem) The present invention aims to achieve the above object.

An abnormality detection circuit for a combustion control device that uses a proportional valve to adjust the fuel supply amount and uses a variable duty pulse to control the proportional valve, which takes in the variable duty pulse and changes its frequency when it is in a normal state. Compare with the frequency band that is scheduled to be approved,
An abnormality Yokoyama circuit for a combustion control device is provided, which outputs an abnormality signal representing an abnormality of a variable duty pulse when the frequency is out of the predetermined frequency band.

When the proportional valve is controlled normally, the fluctuation in the frequency of the variable duty pulse sent to the proportional valve is also within the previously expected frequency range ψ Therefore, the combustion control device The frequency band of this variable duty pulse, which is expected during normal operation, is used as a comparison standard for abnormality detection, and then it is actually sent from the main control circuit to the proportional valve via the drive circuit. By monitoring the frequency of the variable duty pulse, if the frequency taken in is outside the above-mentioned scheduled frequency band, it can be determined that there is some kind of abnormality in the main control circuit or proportional valve drive circuit, etc. I can do it.

The above-described essential structure of the present invention can achieve exactly such an effect.

The abnormality signal obtained from the abnormality detection circuit of the present invention can be used in any way, and the present invention is not limited to such uses. It can be used to command the engine to stop combustion.

In addition to this, it is of course also possible to use it for displaying an alarm.

Embodiments FIG. 1 shows a schematic configuration of a basic embodiment of the present invention.

In the figure, the components designated by the same reference numerals as the components related to the conventional example previously explained with reference to FIG. It is fine to leave the street as it is.

When the fuel supply amount signal circuit So corresponding to the combustion amount at the time is given from the main control circuit 4 to the proportional valve drive circuit 5, the output of the proportional valve drive circuit 5 has a duty signal corresponding to the fuel supply amount at the time. Duty variable pulse SP
occurs.

As described above, this variable duty pulse sp is input to the proportional valve 6 to control it, and the proportional valve 6 thereby controls the effective opening area of the fuel supply path in accordance with the duty at that time. to control the fuel supply amount.

In the embodiment of the present invention, this variable duty pulse Sp is input not only to the proportional valve but also to the frequency abnormality detection circuit 8.

This frequency abnormality detection circuit 8 is given in advance information about the frequency band in which the duty variable pulse Sp should be as long as the combustion control device is operating normally.
Now, this scheduled frequency band is compared with the frequency of the captured variable duty pulse Sp at any given time.

That is, each of the upper and lower limits of the above-mentioned scheduled frequency band is compared with the seven occasional frequencies of the captured duty variable pulse Sp, and if the frequency exceeds the above-mentioned upper limit, or conversely, the above-mentioned When it is further below the lower limit,
The abnormality signal Sa is sent to the main control circuit 4 to take appropriate measures to stop combustion, and conversely, if the frequency of the taken-in variable duty pulse Sp falls within the above-mentioned scheduled frequency band. If there is, let the combustion continue.

As mentioned earlier, the abnormality signal Sa can be used in other ways; for example, it may be used for alarm display, or it may be used as a separate independent signal without passing through the main control circuit 4. The control circuit may be inputted to forcefully stop combustion regardless of the state of the main control circuit.

Further, the above comparison function in the frequency abnormality detection circuit 8 is as follows:
For example, after converting the input frequency and the upper and lower limit values of each station of the planned frequency band into voltages, those skilled in the art can use known and existing electronic circuit techniques, such as by comparing the voltages using an ordinary comparator. It can be realized with any suitable configuration.

<Effects of the Invention> According to the present invention, it is possible to detect when the variable duty pulse that drives the proportional valve has an unacceptable abnormal frequency.

This also means that an abnormality in the main control circuit or proportional valve drive circuit is detected.

Therefore, by appropriately applying the abnormality signal obtained by the present invention, it becomes possible to easily take measures to prevent major accidents such as incomplete combustion.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a basic embodiment of an abnormality detection circuit for a combustion control device according to the present invention, and FIG. 2 is a schematic diagram of a part involved in fuel supply amount control using a proportional valve in a conventional combustion control device. This is a configuration diagram. In the figure, 1 is a water supply temperature sensor, 2 is a hot water supply part sensor, 3 is a water supply amount sensor, 4 is a main control circuit related to combustion, 5 is a proportional valve drive circuit, 6 is a proportional valve, 7 is a temperature setting operation part, 8 is a duty variable pulse frequency abnormality detection circuit.

Claims (1)

[Claims] An abnormality detection circuit for a combustion control device that uses a proportional valve to adjust the amount of fuel supplied and uses a variable duty pulse to control the proportional valve, which takes in the variable duty pulse and adjusts its frequency. , compared with the frequency band expected to be recognized as normal,
An abnormality detection circuit for a combustion control device, characterized in that when the frequency is out of the predetermined frequency band, an abnormality signal representing an abnormality of the variable duty pulse is outputted.