EP0410846A1 - Electric energy-providing device for a circuit, such as a fence - Google Patents

Abstract

The invention relates to a device for circuit electrification comprising means (7) generating high-voltage pulse trains, a source (5) of undulating electric current, capacitors (9) charged in step with the generated pulses, and an element (11) with triggering threshold, coupled to the circuit (3) to be energised and which becomes conducting beyond the specified voltage, so as to deliver the high-voltage energy to the circuit. It will be possible to use a discharger, such as a spark plug for internal combustion engine, as threshold element. The invention applies in particular to the electrification of fences. <IMAGE>

Description

The invention relates to a device for supplying electrical energy to a circuit and more particularly to a high voltage pulse generator device intended in particular to be connected to an electric fence.

The object of the invention is to provide a reliable device making it possible to avoid wasting the energy produced by the current source which supplies the device, while ensuring a controlled discharge of the pulses which makes it possible to increase the quality of the transmission of these pulses in the circuit.

The device of the invention using a trigger point element capable of delivering the high voltage almost instantaneously, for example in the fence, the problem of the life of this element has also been particularly taken into account, taking into account sometimes rigorous conditions of use which the device could face.

To meet these requirements, this device is characterized, in accordance with the invention, in that it comprises:
means for generating pulse trains, said pulse trains succeeding each other with a determined period,
a source of wave electrical current to supply said means for generating pulse trains,
- electrical energy storage means, associated with said generator means and charged at the rate of the pulses generated,
- And a trigger threshold element coupled to the circuit to be supplied, said element being electrically insulating for voltage values lower than a determined voltage taken across said storage means and becoming passing beyond this voltage to deliver to the circuit the high voltage electrical energy stored in said capacitor type storage means.

Preferably, the source of wave electrical current in question will include:
- a low voltage direct current power source, such as a battery or an electrochemical accumulator,
- And timing means associated with this power source to rhythm the supply of electrical energy to the pulse train generator means by controlling the periodicity of the pulse trains generated.

In general, a spark gap will preferably be chosen as the triggering element. In this regard, it will be noted that the tests which have been carried out with spark plugs have been found to be particularly satisfactory, presaging the possibility of ensuring high-voltage electrical discharges at the rate of one discharge per second, and this probably for about ten 'years.

It should be noted that the provision in the invention of pulse generator means working at high voltage will prevent these pulses from being damped over time, while ensuring, in particular in the context of an electric fence, a particularly effective deterrent given the almost instantaneous triggering of the threshold element.

• - la figure 1 est schéma-bloc du dispositif de l'invention,
• - la figure 2 illustre un mode de réalisation de principe du circuit électronique correspondant au dispositif illustré figure 1,
• - les figures 3, 4 et 5 montrent trois courbes représentatives de l'état des signaux électriques en trois points, respectivement A, B et E, du circuit électrique illustré figure 2,
• - et les figures 6, 7 et 8 montrent trois formes possibles de réalisation de l'élément à seuil de déclenchement utilisé dans l'invention.

Other characteristics and advantages of the invention will appear from the following description made with reference to the accompanying drawings given solely by way of example and in which:

• FIG. 1 is a block diagram of the device of the invention,
• FIG. 2 illustrates a principle embodiment of the electronic circuit corresponding to the device illustrated in FIG. 1,
• FIGS. 3, 4 and 5 show three curves representative of the state of the electrical signals at three points, respectively A, B and E, of the electrical circuit illustrated in FIG. 2,
• - And Figures 6, 7 and 8 show three possible embodiments of the trigger threshold element used in the invention.

If we refer first of all more particularly to FIG. 1, we therefore see in its entirety marked 1 the device intended to supply electrical energy under high voltage to a fence 3.

The device 1 essentially comprises a wave (or oscillatory) electric current source 5 supplying a pulse train generator 7 with which storage means 9 are associated, such as capacitors, which are charged at the rate of the pulses generated by the means 7, the capacitors 9 being associated with a trigger threshold element constituted in this case by the spark gap 11. As soon as the voltage of the storage capacities 9 reaches the threshold or ignition value of spark gap 11, that -This produces an electric arc and the electrical energy contained in the means 9 can then discharge almost instantaneously towards the fence 3 through the spark gap, via the resistor 13 which is connected in series.

As illustrated, the current source 5 which supplies the pulse generator 7 essentially comprises a low-voltage direct current supply source 15 (for example 12 Volts), such as a solar cell or an electrochemical accumulator, as well that timing means 17 intended to rhythm the supply of electrical energy to the generator 7 and therefore to control the periodicity of the pulse trains generated by the latter.

Preferably, the generator 7 will be formed around on the one hand an astable multivibrator 19 which will receive the wave signals (generally square signals) delivered from the current source 5 and, on the other hand, voltage multiplier means marked 21 and periodically activated by the multivibrator 19 to deliver trains of positive increasing pulses under high voltage to the capacitor unit 9.

Of course, the various constituent elements of the device will be suitably connected to ground via a common earth line 23.

Let us now turn to Figure 2 to describe more precisely the constitution of different elements of the device of the invention.

On the electronic circuit illustrated in FIG. 2, there is first of all the direct current source 15, the supply line 16 of which is notably connected through the switch 25 to the supply terminal 14 (V _DC input: voltage of closed circuit) of timer 17, which in this case consists of an integrated circuit of CMOS type "556" distributed in particular by the company "TEXAS INSTRUMENTS INC.".

To smooth out any fluctuations in supply, a capacitor 26 connected to ground was connected between the switch 25 and a crossing point 43 of the connection line of the terminal 14.

Although such an integrated circuit of CMOS type "556" used as a timer is quite known, we will briefly recall below how it is connected.

Its inputs 13 and 12 (respectively discharge and threshold inputs) are first of all connected together to ground via the capacitor 27, with in addition a connection to the supply line of the terminal 14 through the resistor 29.

As for the voltage control input terminal 11 of this "556", it is connected to ground by the capacitor 31.

Through the resistor 39, at the terminals of which a capacitor 41 is mounted, the two “Reset” terminals (registration terminals) 10 and 4 of the “556” are looped together, via the point of intersection 43 already mentioned where it connects the supply line of this "556".

The output terminal 9, by which the timer will control the astable multivibrator 19 (which will be described below), is connected to the base of two NPN transistors 33 and PNP 35 interconnected by their transmitter to form a static switch 37.

Trigger terminal 8 is looped to the other output terminal 5 of "556". And a connection with the earth is ensured through three components connected in series, namely the resistor 45, the diode 47 mounted with its cathode to the ground and the capacitor 49 one of the terminals of which is directly connected to ground. In addition, at 53, between the diode 47 and the capacitor 49, is connected a resistor 51 furthermore connected at 55 on the line which connects the aforementioned terminals 5 and 8 of "556".

And the second trigger terminal 6 ("Trigger") is connected between the connection point 53 of the resistor 51 and the capacitor 49, and on this line is connected, at 57, the second threshold terminal 2 ("Threshold" ).

As for the second control input 3 of "556", it is simply connected to ground through the capacitor 59. And the discharge terminal 1 is not used. Finally, the earth terminal 7 is of course connected to ground.

Thus mounted and associated with the current source 15, the timer 17 will therefore generate by its output terminal 9 a wavy signal, of substantially square shape, which will be found at A at the common output of the static switch 37.

The purpose of this switch 37 is to interrupt the power supply to the high-voltage pulse generator 19, each time the spark gap 11 is ignited, thus making it possible to avoid unnecessarily wasting energy from the current source. 15, extending its service life accordingly.

To perform this function, the collector of the NPN transistor 33 has been connected to the supply line 16 of the source 15, the collector of the PNP transistor 35 being in turn connected to ground, while the emitters of these two transistors have have been connected in common to the multivibrator 19 and more precisely, via the junction point 61, to its supply terminal V _cc 7, which terminal is itself connected to ground through the capacitor 63. In the example illustrated , the multivibrator 19 is constituted by a PWM controller (Pulse Width Mode - Generator with variable pulse width), of the "UC 3845" type developed by the company "UNITROD".

This type of component used is well known.

For the record, its connection is as follows:

Its comparison terminal 1 is not used. Its terminal 2 (VFB input) is connected directly to ground.

Its terminal 3 (current control terminal) is looped on the one hand on the ground terminal 5 via the capacitor 65 and, on the other hand, on the output terminal 6 through the resistor 66 and the effect transistor. field 67 (whose neck is connected to output 6 of the multivibrator). A ground connection is also provided through a resistor 68, one of the terminals of which is connected at 69 between the resistor 66 and the transistor 67.

Finally, terminal 4 (R _t / C _t ) of the multivibrator is looped to the 8 V _ref input (reference voltage) via resistor 70, with connection to ground on the one hand between resistor 70 and terminal 4 , through the capacitor 71 and, on the other hand, between the other terminal of the resistor 70 and the input 8, through another capacitor 72.

Thus mounted, the multivibrator will therefore deliver by its output terminal 6 pulse trains whose rhythm will be imposed by the timing means 17, the field effect transistor 67 transmitting these pulse trains to one of the terminals primary winding 73 of a transformer 75, the other primary winding terminal of which is conventionally connected to the supply line 16 of the direct current source 15.

As will be understood from the mounting of the multivibrator 19, the periodicity of the pulses belonging to the same train of pulses will be determined by the resistor 70 and the capacitor 71.

For information, it should be noted that during the tests which were carried out, the amplification ratio of the transformer was chosen to be equal to 20.

To further increase the voltage, so that it reaches approximately 8 to 10,000 V at the input of spark gap 11, a further diode multiplier bridge marked as a whole 79 has been added to transformer 75 (the whole forming the voltage multiplier 21 above).

The multiplier bridge 79 consists in this case of five lines of current rectifier elements (in this case diodes) mounted in parallel with each other and connected on the one hand at the input (at 81) to the one of the terminals of the secondary winding 83 of the transformer 75 (the other terminal of which is connected to ground) and, on the other, at the output (at 85) to the spark gap 11.

As illustrated, the first line of the multiplier bridge 79 comprises four diodes 87, 89, 91, 93 arranged in series and mounted passing in the direct direction considered of the current flowing in the direction of arrow 95 towards the spark gap.

In this arrangement, the last diode 93 of this first line of diodes is also connected to ground by its cathode, through a charge capacitor 97.

As for the second line of the multiplier bridge, it consists of three other diodes 99, 101, 103 always connected in series, but in reverse. And a capacitor 104 interconnects the anode of diode 87 and the cathode of diode 99, via junction points 105 and 107, the latter receiving line 81 of the secondary winding 83 of the transformer.

The third line of the multiplier bridge 79 comprises three diodes 108, 110 and 112 connected in series and passing like those of the first line. A charge capacitor 111 connects the cathode of the diode 112 of the third line to the anode of the diode 103 of the second line, via the junction points 113 and 115.

The fourth line is, in turn, like the second, consisting of three diodes 117, 119, 121 arranged in series but mounted in reverse (that is to say non-passing in a direction parallel to the arrow 95). And another capacitor 123 connects the cathode of the diode 117 and the anode of the diode 108, via the junction points 125 and 127.

Finally, the fifth line comprises three diodes 129, 131 and 133 always arranged in series but mounted passing in the considered direct direction of the current. Here again, a new capacitor 135 interconnects the cathode of diode 133 and the anode of diode 121, via the extreme junction points 137 and 139, the latter point connecting the multiplier bridge 79 and its charge capacitors to the spark gap 11, across the line 85, this spark gap 11 being of course connected to the fence 3 through the resistor 13.

Thus constituted, such a circuit is able to supply for example every 1.5 s (second) a series of pulses spaced about 0.15 ms (millisecond) for example, and this with a voltage of the order from 8 to 10,000 V.

Given these operating conditions and for safety reasons, it was therefore considered preferable to add a cut-off safety control circuit making it possible to interrupt the charging of the energy storage unit 9 (this is ie charge capacitors 97, 104, 111, 123 and 135) in the event that the voltage at the input of the spark gap is greater than its ignition voltage.

As clearly illustrated in FIG. 2, this safety circuit includes a Zener diode 141 connected by its cathode to the junction point 143 which connects the primary winding 73 of the transformer 75 and the cathode of the field effect transistor 67. As for the anode of the Zener diode 141, it is connected, through a resistor 145, to the base of an NPN transistor 147 whose collector is connected at a point 148 of intermediate junction between the initialization terminal 10 of the integrated circuit "556" and the parallel connection of capacitor 41.

In addition, between the resistor 145 and the Zener diode 141, and at three successive junction points, another Zener diode 149, a capacitor 151 and a leakage resistance 153 are connected, these three components being connected to ground, the diode Zener 149 being so by its anode.

Furthermore, in 155, between the resistor 145 and the base of the transistor 147, another resistor 157 is connected, furthermore connected between the emitter of the transistor 147 and the ground.

To complete the circuit, between the resistor 145 and the junction point 155, is connected a resistor 159 connected to ground through the Zener diode 161 (mounted with its anode to ground).

Between the resistor 159 and the diode 161 is also connected to the earth line 23 of the fence on which, at two successive points, are successively connected a capacitor 165 and a resistor 167 also connected to ground.

We also refer now to Figures 3, 4 and 5 to briefly describe the operation of the electronic device that we have just presented.

As soon as the circuit is energized, by closing the switch 25, the timer 17 via the integrated circuit "556" generates a square signal on its output terminal 9.

We find this signal, which we illustrated in Figure 3, at the output of the static switch 37, that is to say at point A of Figure 2. This signal changes between the voltages 0 and + V (supply voltage of the direct current source 15).

Conclusive test results have been obtained by adjusting the clock so that the pulse duration is 150 ms maximum with a periodicity T of approximately 1.5 s.

In practice, taking into account the planned circuit, the supply of the pulse generator will not last 150 ms but rather 15 to 20 ms, time necessary to reach the desired voltage (of the order of 8 to 10,000 V) at the charge capacitors 97, 111 and 135.

Beyond these 15 to 20 ms, the static switch 37 will interrupt the power supply to the multivibrator 19, thereby preventing between two successive pulse trains any energy loss at the current source 15.

Note that it is important that the spark gap 11 starts for a voltage slightly lower than the maximum charge voltage of the capacitors of the storage unit 9, otherwise, taking into account the safety measures taken, the multivibrator 19 will operate until this maximum charging voltage is reached, then will stop, controlled in this by the timer 17.

This stop of the generator 19 intended to avoid any overvoltage will be obtained thanks to the control circuit, by resetting of the integrated circuit "556" via its "Reset" input 10 and through the NPN transistor 147, with detection of the voltage by the Zener diode 141 at the input of the primary winding 73 of the transformer 75, that is to say at B in FIG. 2.

Note that we could also ensure the same control via the Zener diode 161.

However, in normal operating conditions, the multivibrator 19 delivers at B trains of pulses which have been shown in FIG. 4.

As can be seen, the periodicity T of these pulse trains corresponds to that of the signals delivered at A (FIG. 3).

And each pulse train comprises a succession of increasing positive pulses progressively spreading out, every 0.15 ms for example, between the voltage V delivered by the current source 15 and the amplified voltage V₁ (for example from the 85 V).

Although this has not been shown, it will be readily understood that at the output of the transformer (point C in FIG. 2), there will be found a comparable diagram with a higher voltage, function of the amplifier amplification ratio.

It will be the same at point D of FIG. 2, that is to say at the input of spark gap 11, after passage of the signal in the diode multiplier bridge 79.

It will be noted that during the tests which were carried out, the amplification ratio of the transformer 75 had been chosen to be equal to 20, while the diode multiplier bridge 79 had been constructed for a voltage rise ratio of 5, making it possible to reach approximately 8.500 V of charge in the capacitor unit 9.

If this choice of operating voltage is respected, the spark gap should preferably initiate these discharges for a slightly lower voltage, in order to prevent the operation of the pulse generator from being interrupted via the cut-off safety control circuit. , due to overvoltage.

In normal operation, the spark gap 11 through which the capacitor unit will discharge 9, will therefore periodically deliver towards the fence 3 a succession of electric discharges, the trace of which has been illustrated in FIG. 5 (point E of the figure 2).

As can be seen, the periodicity of these discharges is always equal to approximately T with peaks reaching the voltage V₂, which is equal to:
V₂ = V₁ x r₁ x r₂
with r₁ = amplification ratio of the diode multiplier bridge 79, and
r₂ = amplifier amplification ratio 75.

As an element with a triggering threshold, it has been envisaged in the invention to use in particular any type of electronic spark gap usually used as surge protectors.

Of course, in the context of the invention, the spark gap chosen will be electrically insulating for voltage values lower than a determined voltage taken at terminals of the capacitor unit 9 (for example approximately 8,500 V), but will become passing beyond this voltage value to deliver to the fence the high voltage electrical energy contained in the capacitors.

It has also been envisaged to use as a threshold element a spark plug for internal combustion engines and in particular a hot spark plug for cars. In this case, a waterproof cap will be used in addition to confine the atmosphere in which the electrodes bathe at the place where the electric arcs must occur, thus making it possible to reduce the corrosion of the electrodes by the ambient air and to facilitate striking the arc, regardless of the surrounding temperature and humidity conditions. In practice, the gaseous atmosphere prevailing around these electrodes will be ionizable and made up of air, or even possibly inert gases.

In Figure 6, there is schematically illustrated a first embodiment of such a candle.

In this case, it is a conventional candle marked 200 with two electrodes, one straight 201 extending in the main axis 202 of the candle, the other curved 203.

These two electrodes which therefore protrude at the upper end of the spark plug 200 are capped by a cap 205 which is mounted on this spark plug in a gas-tight manner (for example by screwing with a seal if necessary), so reserving around the electrodes a cavity 207 which is isolated from the surrounding external environment.

In practice, this cap should not interfere with the normal functioning of the spark plug. It must therefore be electrically insulating and / or present at the level of the cavity 207 of the interior walls 206 which are sufficiently spaced from the nearest electrode so that when the spark plug becomes passable (that is to say that the voltage d priming is reached), the corresponding electrical discharge actually occurs between the two electrodes 201 and 203.

In FIG. 6, it will also be noted that, on the one hand, 201a has been identified the lower end of the electrode 201 allowing the electrical connection with the circuit and, on the other hand, at 203a, the other electrode of connection of this spark plug which is held in position around the electrically conductive part of the spark plug body by means of a lock nut 209.

In FIG. 7, a second possible embodiment of this same candle has been illustrated, of which only the upper part has been shown.

This spark plug identified as a whole 300 now only has a central electrode 301, the second curved electrode having been removed and replaced by the cap 303 which in this case is electrically conductive.

As before, this cap is still mounted on the spark plug in a gas-tight manner so as to reserve around the electrode 301 a cavity 305 isolated from the surrounding external environment.

It will be noted that the interior walls of the cap 303 which limit the cavity form a substantially cylindrical envelope of circular section whose cylinder axis is substantially coincident with that 302 common to the electrode 301 and to the spark plug as a whole, the dimensions of the cavity thus formed being such that when the candle becomes passable, the corresponding electrical discharge will occur transversely to its axis 302 between the electrode 301 and the cylindrical wall 307 opposite the cap 303, the electrical energy then being transmitted through the connection terminal shown diagrammatically in 309.

As for FIG. 8, it always schematically illustrates the upper part of a third and last embodiment of the candle, in this case identified as a whole 400.

This candle 400 resembles that of FIG. 7 in that it no longer understands, like it, that its only electrode axial central 401. But in this case, the role of the other electrode is played by the electrically conductive part 403 of the body of the spark plug.

To increase at the level of the electrode 401 the surface where the electric arc may be triggered, this electrode is surmounted by a part 405 in the form of an electrically conductive disc.

The disc 405 which therefore comes into contact with the electrode 401 has a substantially flat lower face 406 practically parallel to the opposite face 404 of the electrically conductive part 403 of the body of the spark plug, so that when this spark plug becomes passable, a electric arc can strike at the most suitable point between surfaces 404 and 406.

Of course, a cap 407 comes, as before, to cover the upper end of the spark plug where the electrode 401 projects to reserve around it and its complementary part 405 a cavity isolated from the surrounding medium. In order to avoid any unexpected triggering of an electric arc between one of the electrodes and the cap, the latter will in this case either be electrically insulating, or dimensioned so that its internal walls which limit the cavity 409 are sufficiently spaced apart. from Exhibit 405.

In FIG. 8, it will also be noted that the two junction terminals of the spark plug have been identified in 411 and 413 allowing it to be connected on the one hand to the electronic circuit generating high voltage pulses and on the other hand to the fence 3.

Claims (12)

1. Device for supplying electrical energy to a circuit, comprising:
- means (7) for generating trains of positive high-voltage pulses of high voltage, said pulse trains succeeding each other with a determined period,
a source (5) of wave electrical current for supplying said means (7) generating pulse trains,
- means (9) for storing electrical energy, associated with said means (7) generator and charged at the rate of the pulses generated,
- And an element (11) with trigger threshold coupled to the circuit (3) to be supplied, said element being electrically insulating for voltage values lower than a determined voltage taken at the terminals of said storage means and becoming passing beyond this voltage, to deliver high voltage electrical energy stored in said storage means (9) to the circuit. 2. Supply device according to claim 1 characterized in that the source (5) of wave electrical current comprises:
a source (15) of low voltage direct current power supply,
- And timing means (17) associated with said power source to rhythm the supply of electrical energy to the means (7) generating pulse trains by controlling the periodicity T of the pulse trains generated by the latter. 3. Supply device according to claim 1 or claim 2 characterized in that between the means (7) generator of pulse trains and the source (5) of wave current, is interposed a switch (37) which interrupts l current supply to said generator means (7) substantially during the time interval separating two successive trains of pulses. 4. Supply device according to any one of claims 1 to 3 characterized in that the means (7) generating high voltage pulse trains comprise:
- an astable multivibrator (19) which receives the wave signals delivered by the current source (5),
- And voltage multiplier means (21), periodically activated by said multivibrator (19) to deliver said trains of high voltage pulses to the storage means (9). 5. Supply device according to claim 4 characterized in that the means (21) voltage multiplier comprises a transformer (75) whose primary winding (73) is connected on the one hand to the multivibrator (19) and other part to the DC power source (15) and whose secondary winding (83) is connected on the one hand to ground and on the other hand to a diode multiplier bridge (79) coming to charge said storage means (9). 6. Power supply device according to any one of claims 1 to 5 characterized in that it comprises a cut-off safety circuit (141, 147) for interrupting the supply of electrical energy to the means (7) generating trains pulses when the voltage supplied by them exceeds the triggering voltage of the element (11) at the triggering threshold. 7. Supply device according to any one of the preceding claims, characterized in that the element (11) with a triggering threshold is a spark plug (200, 300, 400) the end of which the electric discharge occurs is covered by a cap (205, 303, 407) which is mounted on the spark plug in a substantially gas-tight manner by reserving around the zone where said discharge occurs a cavity (207, 305, 409) isolated from the surrounding external environment. 8. A feeding device according to claim 7 characterized in that said spark plug being a spark plug with two electrodes (201, 203) for an internal combustion engine, the cap (205) which covers it is electrically insulating and / or sufficiently spaced from the nearest electrode so that when the spark plug (200) becomes passable, the corresponding electrical discharge occurs between the electrodes (201, 203). 9. A feeding device according to claim 7 characterized in that said spark plug is a spark plug with two electrodes for an internal combustion engine, one of the electrodes of which is removed and replaced by said cap (303) which is electrically conductive and covers the l 'remaining electrode (301) so that, when the spark plug (300) becomes passable, the corresponding electrical discharge occurs between this remaining electrode (301) and the cap (303). 10. Feeding device according to claim 9 characterized in that the remaining electrode (301) extends substantially in the general axis (302) of the spark plug and the cavity (305) reserved around this electrode is substantially cylindrical of circular section with its cylinder axis substantially coincident with the axis of the electrode, the diameter of this cavity (305) being such that when the spark plug (300) becomes passable, the corresponding electrical discharge occurs transversely to its axis, between the remaining electrode (301) and the cylindrical wall opposite the cap (303). 11. Supply device according to claim 7 characterized in that said spark plug is a spark plug with two electrodes for an internal combustion engine from which one of the electrodes is removed, the remaining electrode (401) being surmounted, on the side of said end of the spark plug, by an electrically conductive part (405) having a face (406) substantially parallel to that (404) facing an electrically conductive part (403) of the body of the spark plug from which the remaining electrode projects , this projecting part of the electrode and the electrically conductive part (405) being housed in said cavity (409) reserved by the cap, the shape and dimensions of this cavity being such that when the plug (400) becomes passable, the corresponding electrical discharge occurs between said electrically conductive part (405) and the facing part (403) also electrically conductive of the body of the plug. 12. Feeding device according to any one of claims 7 to 11 characterized in that in the cavity (207, 305, 409) defined by the cap (205, 303, 407) prevails an ionizable gas atmosphere consisting for example of 'air.

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