JPH01210719A - Combustion control device - Google Patents

Abstract

PURPOSE:To miniaturize the title device in a case when a circuit, controlling the supply and stop of fuel, is operated electronically through a contactless circuit, by a method wherein a relay contact, capable of intercepting an electric power forcibly, is inserted into an electric power source, generating an electric power driving a solenoid valve. CONSTITUTION:A relay contact 3, capable of intercepting forcibly an electric power for driving solenoid valves SV1, SV2, is inserted into an electric power source 1, generating said electric power. Thyristors 6, 11 are employed as electronic switches to insert a main current line or a current line between an anode and a cathode in series into solenoid valve driving coils 7, 12 while said relay is driven by effecting the turn on of the current line through so-called anode fire. The thyristors 6, 11 are turned on or brought into preparing conditions when the relay contact 3 is closed. The cut off of the relay contact is effected by shortening a distance between the gate and the cathode of the thyristors 6, 11 through the output of a photocoupler.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combustion control device, and more particularly to improvements in making the part that controls fuel supply and stoppage electronic and contactless.

[Prior Art] In conventional combustion control devices, a solenoid valve is used to open and close a fuel flow path, and power is supplied to the drive coil of the solenoid valve to open the valve and vice versa. When closing a valve by cutting off the power supply, a relay is driven to open and close a relay contact inserted directly and in series with the drive coil of the solenoid valve.

[Problems to be Solved by the Invention] However, the conventional method of inserting the relay i point in series and directly into the solenoid valve drive coil is difficult to solve when there are multiple fuel systems that need to be opened and closed individually. Especially when control is required, it is necessary to use two relays for each system, which not only increases the size of the drive power supply for the relay group, but also increases the size of the entire device. I had left it behind.

In addition, since the opening and closing of the relay contacts is directly connected to the opening and closing of the solenoid valve, the spark noise generated when the relay contacts open and close can be a problem, and can also cause malfunctions within the control circuit itself.

On the other hand, nowadays there is a strong demand for downsizing combustion equipment such as water heaters and space heaters, and in order to meet this demand, attempts have been made to make them electronic or contactless.

The present invention was developed under these circumstances, and even when multiple fuel flow paths must be selectively and independently controlled, it is possible to reduce the cost without increasing the number of relays used. In addition to making it possible to use a small electronic switch, it also solves the problem of spark noise from the relay contacts mentioned above.
Normally, various problems that can occur when using electronics in these five types, such as noise generation, element malfunction, and even the risk of element destruction, can be sufficiently reduced, and it is also possible to sufficiently reduce the risk of failure and failure.
It is an object of the present invention to provide a combustion control device that is easy to maintain safety.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a combustion control device based on the following basic idea.

- Even if an electronic switch is used to selectively drive the solenoid valve, at least a relay contact that can forcibly cut off the power should be inserted into the power supply section that generates the power that drives the solenoid valve.

In other words, even though it is electronic, the premise is that at least one relay is used, and by adding the condition that this relay must be driven as one of the conditions for driving the solenoid valve, it is possible to detect abnormalities. If this happens, the power supply to this relay is normally cut off by a command from the main control circuit such as a microcomputer used in this type of control device, and the power supply to the solenoid valve is immediately cut off. Incorporates a fail-safe function that allows the valve to close when the valve is closed.

■After doing so, in order to ensure reliable operation of the electronic switch, a thyristor is adopted as the electronic switch, and this main current line, that is, the current line between the anode and cathode, is inserted in series with the solenoid valve drive coil. and the turn-on is performed by so-called anode fire, so that when the above-mentioned relay is driven and the relay contact is closed, this thyristor is turned-on or is in its preparation state. .

(2) On the other hand, cut-off is performed by shorting the gate and cathode of the thyristor using the output of the photo wig. Of course, when turning on the above, this photo
The coupler output is in a state in which the short circuit between the gate and cathode of the thyristor is removed.

[Operations and Effects] In the present invention, at least one relay is left in place to control the opening and closing of the solenoid valve.

If an abnormality is detected in the combustion system, or even if some problem occurs in the electronic switch part, by cutting off the power supply to this relay, the solenoid valve can be immediately closed, thereby preventing a so-called fail. It is easy to construct a safe mechanism.

Conversely, even if multiple fuel systems are
Even if a dedicated solenoid valve is required for each individual relay, only one relay is required, so there is no need to unnecessarily increase power consumption or increase the size of the device as in the past.

Furthermore, a thyristor is used in the electronic switch part, and this main current path (between the anode and cathode) is connected in series to a solenoid valve, which is configured to be triggered by an anode fire. , and cut-off is achieved by short-circuiting the gate and cathode of the thyristor with the output of the photo-coupler, so for turn-on, first close the relay contact, then close the photo-coupler's above-mentioned To release the short-circuit operation and cut-off, the thyristor can be first turned off using the output of the photocoupler, and then the relay contact can be opened.

Therefore, even if at least one relay is used from a safety standpoint as described above, the spark noise that may occur due to the opening and closing of this relay contact will occur before the ON command is given to the photocoupler. Alternatively, it can be made to occur only after the solenoid valve is turned off, thereby preventing an adverse effect on circuit operation.

Furthermore, although it is incidental, according to the above configuration, the drive phase angle of the thyristor can be controlled depending on the timing of breaking the short circuit due to the photocoupler output, so, for example, by gradually increasing the solenoid valve drive current, It is also possible to prevent sudden supply of fuel.

[Embodiment] The attached drawings schematically show a main part of a preferred embodiment of the combustion control device of the present invention.

In this embodiment, there are two systems that should selectively and independently control fuel supply and stop, each with a solenoid valve SVI
, SV2 supports it. These solenoid valves SVI,
SV2 will also be used in the description below as sono drive coil 7.12.

Each electromagnetic valve drive coil 7.12 is connected in series to the positive and negative terminals of the diode bridge 4, which is the output of the series power supply section, after passing through the anode-cathode current line which is the main current line of the thyristor 6.11. connected between.

The input of the diode bridge 4 is taken from a normal AC commercial power supply 1, and in this embodiment a relay contact 3 is inserted between the AC power supply 1 and the diode bridge 4.

Furthermore, around this diode bridge, a current limiting resistor 2 is inserted in series on the input side to prevent abnormally large current from flowing in, and a bleeder resistor 5 is inserted in parallel on the output side. This is intended to suppress the occurrence of abnormally high voltage.

The relay contact 3 closes when a drive current is supplied to a relay (not shown), and is commonly used in modern combustion equipment such as hot water heaters and space heaters. A control circuit using this is built, and the commands are used to command, for example, the opening or closing of the fuel flow path, so this relay is assumed to be supplied with current by, for example, a fuel supply command signal. can do. Regarding this, it is good to refer to Japanese Patent Application Laid-Open No. 61-22822:11, which was already disclosed by the present applicant, although this is just an example.

However, the thyristor 6.11 is configured to be triggered by anode fire, and considering the circuit configuration, the resistors 8 and 13 are connected between the anode and the gate.
In addition to inserting a resistor 9.14 between the gate and cathode,
The collector of an npn phototransistor 10.15, which becomes conductive when an optical input signal is applied, is connected to the gate of each thyristor, and the emitter is connected to the cathode.

The phototransistor 10.15 may be that of a photocoupler having a pair of light emitting diodes or the like (not shown) as a light emitting source; in other words, it may be an integrated one or a discrete one; Since the source and this phototransistor 10.15 are used together, the phototransistor 10.
The output of No. 15 can be defined as a photocoupler output.

Furthermore, a diode 16.17 for absorbing reverse surge is connected in parallel to each electromagnetic valve drive coil 7.12 to stabilize the switching operation.

To explain an example of operation, when the device has stopped operating,
When a request to stop the fuel supply is issued in any system, the drive signal is not supplied from the control circuit (not shown) to the relay (not shown), so the relay contact 3 is is open.

In this case, the photo-coupler output also short-circuits the gate and cathode of each thyristor, that is, the photo-transistors 10 and 15 are conductive, so that the photo-transistors 10 and 15 have optical inputs. is given. Producing such a signal can easily be implemented with existing control circuits in combustion appliances of this type and is left to the design of those skilled in the art.

Now, if you want to open one solenoid valve SVt and supply fuel to this system, first close relay contact 3, and then
In order to turn off the photocoupler output, the optical input to the phototransistor IO is cut off.

In this way, the drive circuit system of the solenoid valve SVI, which was in standby state with the relay contact 3 closed, receives current from the solenoid valve drive coil 7 as the thyristor 6 is turned on by the anode fire. It operates when fuel is supplied, opens the valve and starts supplying fuel.

One important point here is that the relay contact 3, which tends to generate spark noise when closed, is closed before the solenoid valve is driven, so even if the spark noise occurs, the thyristor This means that it will not adversely affect operation.

In addition, in the illustrated circuit configuration, the thyristor drive phase angle can be controlled depending on the timing of breaking the short circuit caused by the photocoupler output. For example, by gradually increasing the solenoid valve drive current, the fuel It is also possible to prevent sudden supply.

To close the solenoid valve in contrast to the opening operation described above, it is sufficient to first apply optical input to the phototransistor 10 in order to turn off the output of the photocoupler, and then open the relay contact 3.

If you do this, the relay contact will open after the solenoid valve has finished its closing operation, so even if the relay contact 3
Even if sparks occur at this point, there is no problem in terms of circuit operation.

Furthermore, in the case that some abnormality occurs while the solenoid valve is open and the fuel must be suddenly stopped, in the case of the present invention, a relay is connected in series in the power supply line to the solenoid valve. Since contact 3 is interposed, it is sufficient to open this relay contact 3.

The above explanation has been made for one solenoid valve SVI, but as is clear, the second solenoid valve SV2 can be controlled in exactly the same way, and the solenoid valve and the thyristor, phototransistor, etc. inserted in series with it, By increasing the number of similar combinations and connecting them in parallel between the positive and negative terminals of the diode bridge 4, the application is not limited to the two systems shown in the diagram, but can be applied to many more types of fuel systems. can do.

Also, as mentioned earlier, 1. As described in Japanese Unexamined Patent Publication No. 61-228223 already disclosed by the present applicant, it is possible to selectively determine whether or not there is an abnormality in the relay itself that selectively closes the relay contacts 3. The present invention is even more desirable when used in conjunction with a control system.

[Brief explanation of the drawing]

The accompanying drawing is a schematic diagram of an embodiment of the combustion control device of the present invention. In the figure, l is an AC power supply, 2 is a current-eye resistor, 3 is a relay contact, 4 is a diode bridge, 5 is a bleeder resistor,
6 and 11 are thyristors, 7.12 is a solenoid valve drive coil,
8.9.13.14 is a resistor, and 16.17 is a reverse surge absorption diode.

Claims (4)

[Claims] (1) The drive coil of the solenoid valve that controls the supply and stop of fuel and the anode-cathode main current path of the thyristor are connected in series between the positive and negative terminals of the DC power supply, and the DC power supply line is selectively opened. , a relay contact that can be closed, a circuit that turns on the thyristor by anode fire, and a photocoupler that cuts off the thyristor by shorting the gate and cathode of the thyristor. A combustion control device featuring: (2) The DC power supply and the relay contact that can selectively open and close the DC power supply line are kept in one common connection, while the solenoid valve and its anode-cathode main current path are connected to the solenoid valve. A thyristor inserted in series, a circuit that turns on the thyristor by anode fire, and a photocoupler that cuts off the thyristor by shorting between the gate and cathode of the thyristor are combined into one set. The combustion control device according to claim 1, further comprising: a set of combustion control devices. (3) The combustion control device according to claim 1 or 2, wherein a diode for absorbing reverse surge is inserted in parallel with the electromagnetic valve drive coil. (4) The combustion control device according to any one of claims 1 to 3, characterized in that the conduction phase angle of the thyristor is changed depending on the timing at which the short-circuit operation by the photocoupler output is released.