JPH02112190A - Spark detection circuit of capacity discharge type lighting device - Google Patents

Abstract

PURPOSE:To extremely heighten reliability by providing a first judging means confirming that one time spark discharge has a pile of a high-frequency current of two or more times and a second judging means confirming that a generation interval of the high-frequency current is not shorter than a preset time. CONSTITUTION:A pulse number judging circuit 12 inputting an output of a waveform shaping circuit forms a first judging means. The waveform shaping circuit together with a pulse interval judging circuit 13 inputting an output of a reference time pulse generation circuit form a second judging circuit. Only when the first judging means confirms that one time spark discharge has two or more times of a high-frequency current piled on a spark discharge current, while the second judging means confirms that the generation interval of the high-frequency current is not shorter than a preset time, obtainment of a normal spark is judged. Thereby, a stop of operation for confirming the spark and dismantling work for eye observation become needless while extremely heightening reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a spark detection circuit in a capacitive discharge ignition device.

(Prior Art) An example of the prior art will be explained based on FIGS. 15 to 17. FIG. 15 is a basic configuration diagram of a capacitive discharge type ignition device, in which 1 is a power supply section consisting of a commercial power supply AC, 2 is an exciter section, and a transformer 201 that boosts the commercial power supply voltage.
, rectifier diode 202, tank capacitor 203, current limiting resistor 204, spark gap (constant voltage discharge tube 2
05). 3 is the ignition lead part, 4 is the plug 401
This is an equniter section having a

5 is a spark detection coil that is wound several times to several tens of times around the ignition lead that connects the spark cap 205 and the plug 401.

FIG. 16 is a conceptual diagram of a conventional spark detection circuit,
A signal obtained by rectifying and smoothing the induced voltage (■) in the coil 5 due to the spark current (■) using a diode 6 and a capacitor 7 is input to a Schmittlikka circuit 8 and converted into a pulse signal P.

Figure 17 (A) is a waveform diagram of the spark current ■, (B) is a waveform diagram of the voltage ■ induced in the coil 5, and (C) is a waveform diagram of the Schmidts 1 to Triker circuit when the threshold voltage is set to ■. 3 is a waveform diagram of an output pulse P. FIG.

(Problem to be solved by the invention) In this configuration, which uses the pulse signal P from the spark detection circuit to confirm the normal generation of spark, it is possible to check if there is no output from the exciter section or to check the ignition lead. If a short circuit occurs in the ignition lead or igniter part, the spark current will not flow through the ignition lead around which the detection coil is wrapped, so P will be generated and the spark will malfunction as if a normal spark had been obtained. There is.

Similarly, if an insulation failure occurs in the ignition lead or the igniter and a spark is generated at this insulation failure location, the device will malfunction as though a normal spark was being generated.

Therefore, the spark detection circuit having such a configuration has a problem in terms of reliability, and it is difficult to confirm the spark accurately without visual inspection.

An object of the present invention is to provide a spur detection circuit that can solve these problems.

(Means for Solving the Problems) A feature of the present invention is that, in a capacitive discharge type ignition device, a means for detecting a high frequency current superimposed on a spark discharge current, and a means for detecting a high frequency current superimposed on a spark discharge current, a first determining means for checking whether there is superimposition of currents; a second determining means for checking that the generation interval of high-frequency currents is not shorter than a preset time; and logic means for issuing a normal spark output when both outputs of the second determination function are normal.

(Function) The first determination means confirms whether there is a high frequency current superimposed on the spark discharge current or not, and whether there are two or more times in one spark discharge, and the second determination means presets the generation interval of the high frequency current. Only when it is confirmed that the time is not shorter than the specified time, it is determined that a normal spark is being obtained.

(Example) Before describing specific examples, the principle of spark detection by the method of the present invention will be explained with reference to the basic configuration diagram of FIG. 15, which has already been explained in the third national interest section.

Figure 3 (A> is a waveform diagram of the spark current ■ when a normal spark is obtained, and (B) is a waveform diagram of the spark current ■ when a spark is not generated normally due to a short circuit in the igniter section 4. (C) is a waveform diagram of the current ■ when there is an insulation failure in the ignition lead part 3 and a spark occurs in that part. (D) is a waveform diagram of the current ■ when there is an insulation failure in the ignition lead part 3 and a spark occurs. It is a waveform diagram when no occurrence occurs.

In the normal case (A), when the spark gap 204 conducts, a high frequency current H flows to charge the capacitance of the capacitor 203, and at the beginning of discharge and discharge, the line capacitance of the ignition lead flows and is superimposed on the basic waveform W1. do.

Furthermore, when the fundamental waveform approaches zero ampere, the igniter becomes insulated, and the fundamental waveform rapidly approaches zero. When it reaches zero, V2-Vl -Z-, which had held until then,
I Here, ■2... line capacitance charging voltage ■1... capacitor charging voltage Z... discharging circuit 1. , R component composite impedance ■... The relationship between the discharge currents rapidly breaks down, and the high-frequency current H2,1-I3. recharges the line capacitance to maintain balance. )-T4 flows.

Interval 1 where these high frequency currents H, H, H, J-1° appear
1 is the period 1 of the basic waveform W1. /2.

Next, in (B), where a short circuit accident occurred in the igniter section, the commutation near zero ampere in the basic waveform W1 is smooth due to the short circuit, and the high frequency current H, H, which is used to recharge the line capacitance, H4 does not appear. However, in the case of a short-circuit accident in the equniter section, the fundamental waveform is the same as the fundamental waveform W1 in the normal case.

This does not occur due to poor insulation in the ignition lead, but in C>,
Since a spark is generated in the lead section, a high frequency current H1,1-T2. H3114 occurs in the same way as in the normal case (A), but the period of the basic waveform W2 and the interval T2 of high-frequency current generation are smaller than 1゛1 because the resistance and intance of the discharge circuit are smaller than in the case (A). is also shortened by Δt.

In the case (I) in which a disconnection accident occurs in the ignition lead section, the exciter section output is released, so only the high frequency current H1 for initially charging the line capacitance flows.

In this way, by monitoring the number of occurrences of high-frequency current and the interval between occurrences, it is possible to identify whether a spark is normal or not. That is, it can be determined that sparks are normally generated when two conditions are met: the high-frequency current is generated twice, and the high-frequency current is generated at intervals that are not shorter than a certain interval.

The spark detection circuit of the present invention realizes determination based on these two conditions in terms of a circuit.

The basic configuration of the circuit of the present invention will be explained based on the block diagram of FIG. The spark detection coil 5 is shown in FIG.
This is the same as that explained in FIG.

9 is a bypass filter for separating the high frequency signal superimposed on the induced voltage of the detection coil from the fundamental waveform. The frequencies of the basic waveforms W and W2 are expressed in equation 10 as follows: Hy, - equation 10
0 K, Hz, and the frequency of the high frequency current is several tens of M
]-1z, the cut-off frequency of the filter is several M14
7 culm degree is desirable.

10 is a waveform shaping circuit for the output of the bypass filter, and 11 is a reference time pulse generation circuit for manually inputting the output of the waveform shaping circuit.

]2 is a pulse number determining circuit which inputs the output of the waveform shaping circuit, and forms a first determining means.

Reference numeral 13 denotes a pulse interval determining circuit which inputs the outputs of the waveform shaping circuit and the reference time pulse generating circuit, and forms a second determining means.

]4 is an AND circuit which inputs the outputs of the respective determination circuits 12 and 13 and outputs a normal spark determination signal), forming a logic means.

FIG. 2 is an example showing the specific configuration of each element,
Shaping circuit 10 rectifier diode 101. It consists of a parallel circuit of a capacitor 102 and a resistor 103 forming a smoothing circuit, and a monostable multivibrator 104 whose output is 1-reduced.

The reference time pulse generation circuit 11 is composed of a monostable multivibrator which is rotated once by the σ output of the monostable multivibrator 104.

The pulse number determination circuit 12 includes a monostable multivibrator 1
A monostable multivibrator 121 which is trigged by the Q output of 04, an AND circuit 122 which inputs the Q output of this multivibrator and the Q output of the monostable multivib break 104, It consists of a stable multivibrator 123.

The pulse interval determination circuit 13 includes a T flip-flop 131 that receives the Q output of the monostable multivibrator 104 at its clock input terminal and receives the Q output of the monostable multivibrator 11 forming the reference time pulse generation circuit 11 at its reset terminal; It consists of a monostable multivibrator 132 that is tripped by the Q output of this flip-flop.

Q of monostable multivibrator 123 of pulse number determination circuit
The output is input to an AND circuit 14.

In such a configuration, based on the waveforms of each part, the
The operation will be explained with reference to FIG.

Figure 4 is an explanatory diagram of the operation when a normal spark is generated or not, where <A) is the basic waveform and high-frequency current waveform of the spark current a flowing through the ignition lead around which the detection coil is wound, and (B) is the waveform. It is a waveform diagram of one input voltage of the monostable multivibrator 1-04 of the shaping circuit 10, and is a triangular wave synchronized with a high frequency current.

(C), (I)) are the waveforms of the Q and Q output voltages C1d of the monostable multivibrator 104 having a pulse width 'Y'1, where the pulse width '■'1 is 1/2 cycle time of the basic waveform. It is selected to be sufficiently shorter than '1'.

(E) is a waveform diagram of the Q output voltage e of the monostable multivibrator 11 for reference time pulse generation which is tri-inputted by the signal d, and the pulse width is slightly longer than 1/2 period 'I゛ of the basic waveform. The short time 'I'2 is selected.

T flip-flop 1 reset by this voltage e
31 is tripped during the period C of time 'r'2, and is reset at other times.

(F) is the waveform of the Q output voltage f of the T flip-flop 131, (G) is the waveform of the output voltage g of the monostable multivibrator 132, and ()I is the waveform of the output voltage g of the monostable multivibrator 121 of the pulse number determination circuit I2. Waveform of Q output voltage, (
I) is the waveform of the output voltage i of the AND circuit 122, (, J)
(K) shows the waveform of the Q output voltage j of the monostable multivibrator 123, and (K) shows the waveform of the output voltage of the AND circuit 14, respectively.

Figure 5 shows the waveforms of various parts in the case of spark generation due to poor insulation in the ignition lead, Figure 6 shows the signal waveforms of various parts in the case of a short circuit in the igniter, and Figure 7 shows the waveforms of various parts in the case of a short circuit accident in the ignition lead. The waveforms of each part in the case are shown respectively.

(1) Operation of the pulse interval judgment circuit ■When a normal spark is obtained (Fig. 4)'F≧
'I゛2, and the output f of the T flip-flop remains at I-, so the monostable multivibrator 1
The output g of No. 32 is maintained at H.

■When there is a spark in the ignition lead part (Fig. 5), the basic period 1'' is T-<T, ≦'r''?:'', and the output f of the flip-flop 1131 is T1 only during Δt. Become. The monostable multivibrator 132 triggered by this signal emits an output g which is l- during T5.

■Short circuit in the igniter section (Fig. 6) and l! In the case of Ii@ (Fig. 7), the period of the high-frequency signal ]゛'' is infinite, and T“≧
Since T2, the operation is the same as in the case of ■, and f is L2.
level, g is held at H level.

(2) Operation of the pulse number determination circuit The σ output C of the monostable multivibrator 104 is input to the monostable multivibrator 121, and an output that becomes H level only during time '13' is obtained. Time′ in this case
I' is selected such that -T3>T.

The monostable multivibrator 104 is first triggered and then triggered again after T, and obtains an output d which becomes H for a period of T1, which is input to the AND circuit 122.

■When a normal spark is obtained and the spark is broken (Fig. 4), the monostable multivibrator 104 is first triggered and then triggered again after T, and the output d becomes H only during T1.
is obtained and input to the AND circuit 122. At this time, AND
The other input of the circuit is held at H level, and A
The output i of the ND circuit is a pulse output that is at the H level.

This output i triggers the monostable multipipe rake 123 to obtain an output j such that F is at level )(level) during time T4.

■If spark occurs at the ignition lead (Fig. 5) Same as ■.

■In case of short circuit (Fig. 6) or disconnection of igniter (Fig. 7)
(Fig.) Since the monostable multivibrator 104 is trigged only once, the output j is maintained at the ■7 level.

The output g thus obtained becomes an H level unless the generation interval 1'' of the high frequency current is shorter than a preset time. In addition, the output j is the number of occurrences of high frequency current or 2
If the signal g and
The signal is input to the ND circuit 14 to obtain an output k.

The relationship between the spark state and the output is summarized in Table 1 below.

Table 1 As is clear from this table, the obtained output is at H level when a normal spark is obtained, and at L level in all other cases, so it functions as a complete spark detection circuit.

Next, other embodiments of the present invention will be described. FIG. 8 shows another embodiment of the detection coil 5, which is characterized by a configuration that does not require a bypass filter. In other words, the lead wire is connected several times to several times.
0 times Wrap the wire twice and wrap the wire twice. Second coil 501
, 502, the winding start of the first coil and the winding end of the second coil are connected, and the winding start of the second coil and the winding end of the first coil are connected to take out the combined output.

FIG. 9 is a waveform diagram illustrating the operation of this detection coil, in which (A) is the spark current (2) and (B) is the induced voltage in the first coil, which is a differential waveform of (A). (C)
is the composite waveform of the induced voltage of the two detection coils, and since the two coils are connected in reverse, the fundamental wave components cancel each other out and become zero, but the high frequency current component is mainly generated by the conductor through which the spark discharge current flows. Since the coils and the coils are electrostatically coupled and do not cancel each other out even if the coils are connected in reverse, it is possible to detect high frequency components in the composite waveform as shown in (C).

Therefore, when using a detection coil having such a configuration, a bypass filter is not required. FIG. 10 shows an embodiment in which this detection coil is applied to the spark detection coil of the present invention.
The configuration is the same as that except for .

FIGS. 11A and 11B show an embodiment in which the charging voltage of the capacitor 203 is divided by the resistors vcR1 and R2 or the capacitor C1C2 to detect a high frequency current.

FIGS. 12(A) and 12(B) show an embodiment in which the output voltage of the exciter 205 is divided by resistors R, R2 or capacitor C1C2 to detect a high frequency current.

FIG. 13 shows an embodiment in which a cylindrical conductor 503 that is electrostatically coupled to a conductor through which a discharge current flows is used as a detection means. The circuit configuration is the same as that in FIG.

The detection coil is not limited to the exciter output section, but may be installed at any location where the spark discharge current flows.

The spark detection circuit of the present invention is applicable not only to the basic configuration shown in FIG. 15 but also to a capacitive discharge type ignition device in which an ignition transformer 15 is inserted in the exciter output section as shown in FIG. 14. This can be realized by coupling a detection coil to the output part of the transformer.

(Effects of the Invention) As explained above, according to the present invention, in response to any failure or abnormality from the exciter section to the igniter section,
Since a pulse output signal is obtained only when a normal spark is obtained, there is no need to stop operation to check the spark or remove it for visual inspection, making it possible to realize an extremely reliable spark detection circuit. Furthermore, the efficiency of failure detection and maintenance work can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a configuration diagram showing a specific example of the elements shown in FIG. 1, FIG. 3 is a spark current waveform diagram explaining the present invention in detail, and FIG. 7 to 7 are voltage waveform diagrams of various parts for explaining the operation of the circuit of the present invention, FIG. 8 is a configuration diagram showing another embodiment of the detection coil, FIG. 9 is a waveform diagram for explaining the operation, 10 is a circuit configuration diagram when using the detection coil shown in FIG. A configuration diagram showing still another embodiment of the coil, FIG. 14 is a circuit diagram showing an embodiment in which the present invention is applied to a capacitive discharge type ignition device using an ignition coil, and FIG. 15 is a capacitive discharge type ignition device. Fig. 16 is a basic configuration diagram showing an example of the conventional technology, Fig. 17 is a basic configuration diagram of
The figure is a waveform diagram for explaining the operation. 5... Spark detection coil 9... Bypass filter 10... Shaping circuit 11... Reference time pulse generation circuit 12... Pulse number determination circuit 13
... Pulse interval judgment circuit 14 ... AND circuit

Claims (1)

[Claims] In a capacitive discharge type ignition device, there is a means for detecting a high frequency current superimposed on a spark discharge current, and a means for detecting a high frequency current superimposed on a spark discharge current, and a
a first determination means for confirming that high-frequency currents are superimposed more than once; a second determination means for confirming that the generation interval of high-frequency currents is not shorter than a preset time; and these first and second determinations. A spark detection circuit for a capacitive discharge ignition device, comprising logic means for issuing a normal spark output when both outputs of the functions are normal.