JPH0419329Y2 - - Google Patents

Description

[Detailed description of the invention] <Field of industrial application> The invention relates to ignition devices for fan heaters or so-called FF heaters that use gas or gasified oil as fuel, and is particularly applicable to capacitors for storing discharge energy. The present invention relates to an improvement in a device that obtains discharge energy by discharging stored charge.

<Prior art> There are many types of conventional discharge ignition devices in terms of their specific circuit configurations, but especially in the real world where simplification of the circuit is the primary priority. In terms of operating principles, all models are generally similar; when using a commercial AC power supply, the capacitor is charged during the positive half cycle of the AC power supply, and then transferred to the negative half cycle. When the power supply polarity is reversed, the charge stored in the capacitor is instantly discharged to the primary winding of the ignition transformer, and discharge sparks are sent to the discharge gap connected to the secondary winding of the transformer.

<Problems that the invention aims to solve> However, these days, without using a pilot burner,
As the demand for combustion equipment that directly ignites the main burner, or equipment that has the combustion section installed indoors, has increased, problems that have not been considered problems in the past have begun to be pointed out. .

One of these problems is the problem of odor caused by gas being released into the room even within a short period of time from the start of the ignition operation until the fuel actually ignites.

Indeed, even if this were within a safe range in terms of safety, when looking at this type of combustion equipment as a product, it would greatly reduce its value, and in fact, it would be harmful to the user. is also extremely unpleasant.

However, as is clear from the operating principle described above, in conventional ignition devices of this type, the first discharge operation does not occur unless there is a reversal of the power supply phase and, in fact, there is no delay even further than that. Therefore, unless some special improvement measures are taken, there is an unavoidable time delay between the start of the ignition operation and the actual generation of discharge sparks, which sometimes causes problems.

Furthermore, when a commercial AC power source is used, a unit discharging operation can be performed only once per cycle of the commercial AC power source, and the efficiency of use is not good.

The present invention was developed in consideration of these points, and as seen in conventional ignition devices of this type,
Breaking away from the principle of relying solely on the reversal of power supply polarity to discharge a capacitor that stores discharge energy, the system exceeds the peak voltage at which the capacitor is fully charged in each half-wave of the AC power supply, and decreases toward zero crossing. It is an object of the present invention to provide an ignition device that detects a predetermined value in the vicinity of the zero crossing in the process of detecting a predetermined value, and forcibly discharges the accumulated charge in the capacitor at this time.

<Means for Solving the Problems> In order to achieve the above object, the present invention proposes an ignition device having the following configuration.

First, the discharge ignition device to be improved by the present invention, or the prerequisite structural requirements of the present invention, is that the series circuit of the discharge energy storage capacitor and the ignition transformer primary winding has a control input. When the switching elements are connected in parallel and a part of the charge accumulated in the capacitor is discharged and flowed into the control input of the first switching element as a control current, the first switching element is made conductive. Charge the capacitor in advance,
The remaining accumulated charge must be discharged into the primary winding of the ignition transformer, producing a discharge spark in the discharge gap connected to the secondary winding of the ignition transformer. However, this configuration requirement alone is the same as the basic configuration of this type of discharge ignition device disclosed in the past, and there is no difference at all.

Rather, the present invention is characterized by the addition of the following structural requirements in addition to these basic structural requirements.

First, a diode bridge 3 which full-wave rectifies the commercial AC power supply 1 and outputs a pulsating current to charge the capacitor 5;
A diode 4 is inserted in the forward direction when looking at the capacitor 5 from the positive terminal of the capacitor 5, and allows the pulsating current to charge the capacitor 5 to pass through, but blocks the discharging current from the capacitor 5 to the diode bridge 3 side. establish.

Here, the symbols in parentheses correspond to the symbols attached to each component used in the embodiment of the present invention to be described later. Next, in response to the control input from the capacitor 5 to the first switching element 8,
A resistive line 10 is provided for discharging a portion of the charge accumulated in the diode bridge 3 as the control current, and voltage dividing circuits 11 and 12 are provided for dividing the pulsating output from the diode bridge 3.

Then, the divided potential of the voltage dividing circuits 11 and 12 is received at the control terminal, and when this divided potential exceeds a predetermined potential that is slightly higher than zero potential, it is turned on and the resistor line 10 is turned on. It shunts the flowing current to prevent conduction of the first switching element 8, and turns off when the divided potential becomes equal to or lower than the above-mentioned predetermined potential, and releases the shunt to prevent the current flowing through the resistance line 10. A second switching element 13 is provided which feeds into the control input of the first switching element 8.

<Function> The full-wave rectifier diode in the charging circuit used in the present invention effectively utilizes the positive and negative half waves of the commercial AC power source. In other words, as explained below, when looking at the output of the diode bridge, whether the commercial AC power supply is in the positive half cycle or the negative half cycle, the operating power supply voltage range is in either the positive or negative region ( Since the discharge voltage can be fixed in the positive region in general, the device of the present invention can be expected to perform a similar discharge operation in each half cycle.

For the sake of simplicity, let us consider, for example, the positive half cycle of a commercial AC power supply.In the process in which the power supply voltage of the commercial AC power supply rises to its peak value, for example, with the start of the positive half cycle, this diode The diode connected to the bridge output becomes forward biased and the capacitor continues to charge after the start of the positive half-cycle of the supply voltage until it reaches its peak value and eventually reaches its maximum charge. The amount of charge is accumulated up to a value approximately corresponding to the peak value of the positive half cycle with high capacity.

However, even during the positive half cycle, once the peak value is exceeded, the power supply voltage tends to decrease.
This means that the diode inserted in series in the capacitor charging line so as to be in the forward direction during the transition period from the start of the positive half cycle to the peak value will be reverse biased from then on. Then, open the charging line.

On the other hand, according to the present invention, a second switching element is provided, which monitors the power supply voltage through a voltage dividing circuit, and detects when this reaches a predetermined value near zero crossing.

When the predetermined value is detected, the second switching element functions to discharge a part of the charge accumulated in the capacitor as a control current to the control input of the first switching element, thereby promoting the switching. However, in other words, the second switching element bypasses the control current to prevent the control current from flowing into the first switching element before detecting the predetermined value. There is.

In any case, the ignition device configured according to the present invention starts charging the capacitor via the first switching element when the second switching element detects a predetermined value, without waiting for the reversal of the power supply phase as in the conventional case. is suddenly released into the primary winding of the ignition transformer, and a discharge spark is thrown into the discharge gap connected to the secondary winding of the ignition transformer, and this process is repeated once for each half-wave of the power supply.

<Embodiment> The attached drawings show the main circuit configuration of a preferred embodiment of a discharge ignition device constructed according to the present invention.

An AC power supply 1, which may generally be a commercial AC power supply of 50Hz to 60Hz, is connected between a pair of AC input terminals of a full-wave rectifier diode bridge 3 via current limiting resistors 21 and 22 in series. Between the positive and negative terminals of the diode bridge 3,
The capacitor 5 for storing discharge energy, the primary winding 61 of the ignition transformer 6 and the diode 4 provided according to the invention are connected in series. Note that the reason why the current limiting resistor is divided into two resistors 21 and 22 and inserted into each of the pair of AC lines is to reduce the power burden per one.

In this embodiment, the diode 4 inserted between the diode bridge 3 and the capacitor 5 is oriented in the forward direction when viewed from the positive terminal to the negative terminal of the diode bridge 3, and its anode is connected to the diode. - Connected to the positive terminal side of bridge 3.

A thyristor 8 selected as the first switching element is inserted in parallel with the series circuit of the capacitor 5 and the primary winding 61 of the transformer 6, and the so-called gate terminal as a control input is connected to the connection point of the resistors 9 and 10. It is connected. In this embodiment, therefore, the control current to the control input of the first switching element referred to in the summary takes the form of a gate current to the gate of the thyristor 8.

Furthermore, at the connection point between the resistors 9 and 10, there is also a switch selected as the second switching element in this embodiment.
The collector of the npn transistor 13 is connected, the emitter of the transistor 13 is connected to the negative terminal of the diode bridge 3, and the base is connected to the connection point of the resistors 11 and 12 inserted in series between the positive and negative output terminals of the diode bridge 3. It is connected.

The configuration of the primary winding 61 side of the ignition transformer 6 is as described above, whereas on the secondary winding 62 side, a discharge gap 7 consisting of a pair of opposing electrodes is illustrated as an example in principle. There is.

As a result of full-wave rectification, the output of the diode bridge 3 becomes a pulsating current with a frequency twice that of the commercial AC power supply 1, but if we consider the rise of one wave of the pulsating current, we can see that the diode bridge As the positive terminal side of 3 increases its potential in the positive direction,
At this time, via the diode 4 which is in the forward direction, the capacitor 5 for storing discharge energy, the ignition transformer primary winding 61, the diode bridge 3
A charging current flows through the capacitor 5 along the path toward the negative terminal of the current, and this state continues until the peak value of one wave of the pulsating current (half wave of AC power supply) is reached.

On the other hand, the voltage across the capacitor 5, which is charged to the maximum voltage that is approximately equal to the peak value, is applied across the resistors 9 and 10, and its voltage division point is also connected to the gate terminal of the thyristor 8. However, at this time, the npn transistor 13 is still in the on state as shown below, and the resistor 9 is essentially short-circuited, so the gate current flows from the capacitor 5 to the gate terminal of the thyristor 8. is bypassed to the main current path between the emitter and collector of the transistor 13 that is turned on, and does not flow to the gate terminal.

After that, when the output potential of diode bridge 3 exceeds the peak value and starts to decline even if it is within the positive range, the potential across the capacitor due to the charge stored in capacitor 5 is higher than the positive potential of diode bridge 3. The potential becomes higher than the terminal potential, and the diode 4 becomes reverse biased.

Therefore, the capacitor 5 continues to be charged to the maximum voltage corresponding to the peak value of the power supply voltage.

However, when the power supply voltage eventually drops to almost zero, the npn transistor 1 receives the base voltage from the voltage dividing point of resistors 11 and 12.
3 turns off.

Then, the substantial short-circuit condition of the resistor 9 (which can also be called a bypass condition of the gate current) is released, and a portion of the electric charge charged in the capacitor 5 passes through the resistor 10, and then becomes relatively The current flows into the gate terminal of the thyristor 8, which has a lower impedance path than the resistor 9 side, and forcibly turns it on.

When the thyristor 8 turns on, the accumulated charge in the capacitor 5 is transferred to the anode of this thyristor.
Ignition transformer 6 via main current line between Kasoda
The primary winding 61 of the secondary winding 61 is suddenly discharged, and while generating an oscillating current, discharge sparks are sent to the discharge gap 7 connected to the secondary winding 62 side. Note that the smaller the period of the oscillating current at this time, the smaller the structure of the ignition coil 6 can be, and the more the conversion efficiency can be improved.

This is the basic operation of this device, but in the above embodiment, the detection of the near zero crossing value in the positive and negative swinging voltage waveform of the commercial AC power supply 1 is performed with respect to the pulsating current waveform after full-wave rectification. This is done indirectly by detecting that the value has become near zero.

However, instead of this, it is also possible to adopt a circuit configuration that directly monitors and detects the near-zero crossing value at the input AC stage of the diode bridge.

However, as mentioned above, it is better to monitor the ripple current voltage of the diode bridge output, which can perform unipolar processing.
Generally, it can be a simple circuit configuration.

Furthermore, encouraging switching of the first switching element by detecting the predetermined value means, in other words, preventing switching until then, and the above embodiment can be said to be based on this case. .

Of course, as long as the above operation of the present invention can be obtained,
There is no limitation to the illustrated circuit example;
For example, each switching element 8, 13 may be used in a manner other than that shown.

Further, the predetermined value related to the detection of the second switching element can be determined by design by setting various circuit parameters such as the characteristics of the switching element used and the constants of the voltage dividing circuit.

<Effects of the Invention> In the present invention, the discharge operation is started by detecting a predetermined value set in the vicinity of zero crossing in each half-wave of the power supply voltage, so that the following effects can be obtained.

Since the unit discharge operation can be performed twice per cycle of the commercial AC power supply, the efficiency of power usage is high and the output energy of the device is improved.

The maximum charging voltage of the capacitor can be increased to a value approximately equal to the peak value of the power supply, resulting in large output energy.

Since the discharge operation is forcibly caused at a predetermined value near the zero crossing of the commercial AC power supply, it is resistant to fluctuations in power supply voltage and generates little energy loss and noise.

Unlike conventional methods, where the discharge operation starts after reversing the polarity of the AC power source, or even later than that, the discharge operation can start earlier and at a more stable timing, which eliminates unpleasant raw fuel leakage can be suppressed to a minimum, and ignition noise etc. can also be reduced.

In addition, from another point of view, the ignition timing, which was conventionally determined uniquely by the power supply frequency, can be changed by the selection of various parameters according to the present invention.
It can also be said that by adjusting the detection target predetermined value in the vicinity of the zero crossing by raising or lowering it within a certain range, it is possible to create a degree of freedom in design that allows setting at a desired timing.

[Brief explanation of drawings]

The accompanying drawing is a schematic diagram of a preferred embodiment of the discharge ignition device of the present invention. In the figure, 1 is an AC power supply, 21 and 22 are current limiting resistors, 3 is a diode bridge, 4 is a diode, 5 is a capacitor for storing discharge energy, 6 is an ignition transformer, 61 is a primary winding of the ignition transformer, 6
2 is an ignition transformer secondary winding, 7 is a discharge gap, 8 is a thyristor exemplified as a first semiconductor switching element, 9, 10, 11, 12 are resistors, 13 is an npn transistor exemplified as a second switching element, It is.

Claims (1)

[Claims for Utility Model Registration] A first switching element with a control input is connected in parallel to a series circuit of a capacitor for storing discharge energy and a primary winding of an ignition transformer, and the above-mentioned control input of the first switching element is connected in parallel. When the first switching element is made conductive by discharging and flowing a part of the charge accumulated in the capacitor as a control current, the remaining charge that has been previously charged and accumulated in the capacitor is transferred to the ignition transformer. A discharge ignition device that discharges to a primary winding and obtains a discharge spark to a discharge gap connected to a secondary winding of the ignition transformer; A diode that charges the capacitor 5 above.
Bridge 3; inserted in the forward direction when looking at the capacitor 5 from the positive terminal of the diode bridge 3, allowing the pulsating current to charge the capacitor to pass, but discharging current from the capacitor to the side of the diode bridge. a resistor line 10 for discharging a part of the charge accumulated in the capacitor as the control current in response to the control input from the capacitor 5 to the first switching element 8; Voltage divider circuits 11 and 12 that divide the pulsating output from the diode bridge 3; control terminals receive the divided potentials of the voltage divider circuits 11 and 12, and the divided potential has a value slightly higher than zero potential; When the potential exceeds a predetermined potential, it is turned on, bypassing the current flowing through the resistance line 10 and blocking the conduction of the first switching element 8, while the divided potential becomes below the predetermined potential. a second switching element 13 which is turned off at times and releases the shunt and provides the current flowing through the resistive line 10 to the control input of the first switching element 8;
A discharge ignition device comprising: and;