JPS6059431B2 - Leak state detection method and device in high voltage circuit section of internal combustion engine ignition system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting a leak state in a high voltage circuit that constitutes an ignition circuit of an internal combustion engine or the like.

The ignition circuit for internal combustion engines using the high-voltage ignition method generally has a high-voltage circuit consisting of an ignition coil, coil cord, distributor, plug cord, and spark plug. Number 1 generated from the output end
The high voltage of OKV is supplied to the distributor through the coil J cord, distributed to each cylinder of the engine by the rotation of the distributor, and supplied to the spark plug of each cylinder through the plug cord. generates sparks.

The high voltage circuit is arranged to ensure high insulation from the engine body, ignition circuit system, etc., and to prevent the high voltage transmitted to the high voltage circuit from leaking to the engine body, etc. For example, in an ignition coil that generates high voltage, the primary coil on the low voltage side and the secondary coil on the high voltage side that make up the ignition coil are shielded with resin or the like with excellent insulation, and furthermore, the secondary coil The output terminal and the ignition coil body have a structure that has sufficient insulation. Further, the coil cord and plug coat are coated with rubber or the like having sufficient insulation properties for the core wire carrying high voltage. Furthermore, the distributor includes a rotatable center electrode section for distributing the high voltage supplied by the coil cord from the secondary output terminal of the ignition coil to each cylinder, and a plurality of electrodes arranged for each cylinder. The external electrode portions are integrally molded from a highly insulating resin material, and these electrode portions have a structure that ensures sufficient insulation from the outside. Furthermore, in the case of a spark plug, the center electrode of the spark plug to which the high voltage is supplied is integrally molded with a highly insulating insulator or the like to ensure sufficient insulation from the engine body. Therefore, these high-voltage circuit sections have a highly insulating structure that allows the high voltage of several tens of kilograms output from the secondary output terminal of the ignition plug to be transmitted to the ignition plug without leaking to the engine body, etc. This is what we are doing. However, if pinholes, cracks, etc. occur in some of the elements constituting the high voltage circuit due to aging or damage, there is a problem in that high voltage leaks to the outside from the defective parts.

FIG. 1 shows the main parts where the high voltage generated from the ignition coil causes voltage leak in the high voltage circuit of an engine using the high voltage ignition method.

FIG. 1 shows that one end of the coil cord CC, CCl, is connected to the secondary output terminal of the ignition coil IG, and the coil cord CC
The other end CC2 is connected to the center electrode of the distributor cap DC, one end PCl of the plug cord PC is connected to the outer electrode of the cap DC, and the other end PC of the plug cord PC is connected to the outer electrode of the cap DC.
2 shows the state where it is connected to the spark plug PL. According to the above connection relationship, the high voltage of more than ten KV generated from the secondary output terminal of the ignition coil IG is transmitted to the rotor R disposed in the gear 4 knob DC of the distributor DB via the coil cord CC.
In a multi-cylinder engine, the rotor RO is connected to the drive shaft of the engine and rotated by applying an electric current to the center electrode of the rotor RO (not shown in the drawing because the internal view is not shown in Figure 1). , a high voltage is distributed to the outer electrodes in the distributor DB corresponding to each cylinder. The high voltage distributed to each cylinder by the distributor DB is applied to the spark plug PL connected to each plug cord PC via the plug cord PC for each cylinder, thereby producing an electric spark to the spark plug PL. The gas mixture in the engine cylinder is ignited and combusted to operate the engine. In the ignition circuit consisting of the above connections and operations, 1 is A in the drawing.
Voltage leakage is likely to occur in the parts B, C, and D. That is, if a crack or the like occurs in part A due to damage or deterioration of the coil cord CC, a voltage leak occurs to the vehicle body part E or the like adjacent to the coil cord CC. In addition, in part B, if the surface of the distributor cap DC made of a highly insulating resin material becomes wet or soiled,
The outer electrode of the cap (■) and a distributor D made of a metal material
Voltage leakage occurs in the B body. Furthermore, if cracks occur in section C due to damage or deterioration of the plug cord PC, the air cleaner A adjacent to the plug cord PC
Voltage leakage occurs in the C and the engine body (not shown). In addition, in section D, if the surface of the highly insulating insulator of the spark plug PL is wet with water or soiled, or if a crack occurs in the insulator, the engine body EB or the spark plug PL
voltage leak to the ground side of the If these voltage leaks occur in some of these parts while the engine is running, it will not only induce a misfire in the engine and cause the engine to malfunction, resulting in extremely large damage to the engine, but also cause combustible substances such as gasoline. In engines that use high-temperature fuel, the fuel may ignite due to the generation of sparks due to voltage leakage, leading to a fire, resulting in an extremely dangerous situation in automobiles.
Therefore, it is extremely important to efficiently supply the high voltage of tens of kilograms generated from the ignition coil IG to the ignition plug PL without causing a voltage leak in the middle of the high voltage circuit. Coil cord CC that transmits the high voltage
l Distributor DB, plug cord PC, spark plug PL, etc.
It must be managed to maintain normal conditions at all times. Conventionally, voltage leaks in these high-voltage circuits darken the surroundings of the high-voltage circuits, and workers visually judge the discharge light caused by the spark discharge caused by the voltage soak, or Workers used to judge the sound of discharge breakdown by hearing.

According to these conventional methods, in the case of a minute voltage leak, the discharge light due to the voltage leak becomes weaker and the discharge breakdown sound also becomes smaller, so that it can be used under noisy conditions during engine operation or under normal work lighting. However, there was a problem that it was extremely difficult to judge. The present invention has been made to solve the above-mentioned conventional drawbacks, and is a leak state detection method and device in a high voltage circuit section of an internal combustion engine ignition system that can quantitatively measure the leak state without relying on the sensibility of the operator. The purpose is to provide

In order to achieve the above object, a first invention according to the present invention provides a coil cord connected to an ignition coil of an internal combustion engine ignition system, a distributor connected to the coil cord, and a plurality of plug cords connected to the distributor. , a high-voltage circuit unit equipped with a spark plug connected to each of the plug cords is electrically insulated between the plug cord and the spark plug while the high-voltage circuit unit is installed in the internal combustion engine, and the engine The leak state is detected by cracking driving the ignition coil to operate the ignition coil, and detecting and determining a leak signal based on a leak phenomenon occurring in the high voltage circuit in synchronization with the operation signal of the ignition coil. It is characterized by being designed to detect.

The principle of the present invention will be explained below. FIG. 2 shows a cross-sectional view of a high voltage cord such as a coil cord CC or a plug cord PC that constitutes a high voltage circuit section of a typical vehicle. In the high voltage cord, the periphery of the conductor C1, which is the core wire, is usually made of highly insulating rubber C2 with a thickness of 3 TWL.
The conductor is coated to prevent the high voltage of several tens of kilometres, applied to it, from leaking to the outside. However, if cracks or pin holes C3 occur in these high-voltage cords due to aging or damage to the insulation coating, voltage leaks from the damaged portions to the outside, ie, to the nearby engine, body ground, etc. E. Therefore, a pinhole is made in a part of the high-voltage cord, and the distance between the outer diameter of the high-voltage cord and the ground, that is, the air gap length, is set as D, and when a high voltage is applied to the conductor of the high-voltage cord and a voltage leak occurs. FIG. 3 shows the relationship between the gap length D and the leakage voltage. In Fig. 3, the solid line a is
When the high-voltage cord surface is dry, the broken line b indicates a case where the high-voltage cord surface is wet with water. For example, in solid line a, if the air gap length is 5wm, the leakage voltage is approximately 19KV1 air gap length 10711! n
In this case, the leakage voltage is about 30KV. Therefore, in the normal normal vehicle ignition circuit described above, a high voltage of 20 KV or more is generated from the secondary coil IG2 of the ignition coil IG, so the determination level of the determination circuit is set to be equivalent to 1. If you set it, it will cost about 57rr! It can be seen that a voltage leak with an air gap length of n can be determined. Also, depending on the value of the high voltage output from the ignition coil IG,
It goes without saying that by setting the determination level of the determination circuit with reference to FIG. 3, it is possible to arbitrarily determine the magnitude of voltage leakage. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 4 shows a block diagram of the leak state detection device 1 based on the embodiment of the present invention and the connection relationship between the ignition circuit of the vehicle to be measured, and FIG. A specific electric circuit based on the diagram is shown in FIG. 6, and a time chart of signal waveforms at each part in FIGS. 4 and 5 is shown, respectively.

The leak state detection device 1 according to this embodiment is comprised of a waveform shaping circuit 8, a synchronization circuit 9, a detection circuit 3, a determination circuit 4, and a display circuit 5, as shown in FIG.

The waveform shaping circuit 8 includes a resistor 800 as shown in FIG.
, 801 and diodes 802, 80.
Noise limiter consisting of 3 and resistors 804, 805,
806, capacitors 807, 808 and operational amplifier (
A low-frequency Tonami circuit (hereinafter abbreviated as operational amplifier) consisting of 809
The primary coil of the ignition coil IG is connected to the input terminal of the resistor 800 by the synchronizing signal cable 7. A primary voltage signal (FIG. 6a) is input from the terminal of IGl.

Since the primary voltage signal a includes an oscillating voltage component of several hundred volts, the voltage is divided down to the operating voltage level of the waveform shaping circuit 8 by a voltage dividing circuit including resistors 8) 00 and 801. The oscillating voltage component is removed from the signal by the LPF circuit section, and the signal is converted into a rectangular signal (FIG. 6b) by the next-stage comparator section. Similarly, as shown in FIG. 5, the synchronous circuit 9 includes a first monomulticircuit consisting of an integrated circuit (hereinafter abbreviated as 1C) 900 having a monostable multivibrator function, a resistor 902, and a capacitor 901;
C9O3, a second monomulti circuit consisting of a resistor 905, and a capacitor 904, and the first monomulticircuit connects a resistor 902 and a capacitor in synchronization with the rising edge of the rectangular signal (FIG. 6b). A sampling signal (FIG. 6c) having a fixed time width determined by the time constant of 901 is generated and output to the sample and hold circuit section of the next stage detection circuit 3.

Further, the second mono-multi circuit generates a reset signal (see FIG. 6) with a fixed time width determined by the time constant of the resistor 905 and the capacitor 904 in synchronization with the falling edge of the rectangular signal (see FIG. 6b). d) and outputs it to the peak hold circuit section of the next stage detection circuit 3. As shown in FIG. 5, the detection circuit 3 includes a voltage divider circuit made up of resistors 300 and 301, a noise limiter made up of a resistor 302, diodes 306 and 307, and an amplifier circuit made up of resistors 303, 304 and 305 and an operational amplifier 308. and diode 31
0,311, a peak hold circuit consisting of a resistor 312, a capacitor 313, a gate element 317, and an operational amplifier 309, 315, a gate element 3, 18, a resistor 319,
It consists of a sample and hold circuit consisting of a capacitor 320 and an operational amplifier 321.

The secondary coil I of the ignition coil IG is connected to the input terminal of the resistor 300 of the detection circuit 3 via the high voltage cable 2.
Output end of G2. A high voltage signal (Fig. 6 e) is input from the primary voltage signal (Fig. 6 e), and the maximum value of the high voltage signal e is
The signal is held in the peak hold circuit section in synchronization with Figure a). That is, the high voltage signal e is applied to the ignition coil in synchronization with the rising edge of the primary voltage signal a. - Since the signal is generated from IG, a gate element 317 such as an FET is provided in the peak hold circuit section and is operated by the reset signal d input from the synchronous circuit 9, so that the maximum The value is held in synchronization with the cranking drive rotational speed of the engine. The hold output of the peak hold section (FIG. 6f) is converted into a DC signal (FIG. 6g) by the operation of the next-stage sample and hold circuit. That is, the gate element 318 such as an FET of the sample-and-hold circuit is driven by the sampling signal (FIG. 6c) inputted from the synchronization circuit 9, and the hold signal f is matched with the period of the primary voltage signal a. By synchronizing and holding, the primary voltage signal a is converted into a DC signal g that changes every cycle of the primary voltage signal a in proportion to the maximum value of the high voltage signal e. This DC signal g is input to the determination circuit 4 at the next stage. The determination circuit 4 also has a fifth
As shown in the figure, it consists of resistors 400, 401, 403, a diode 402, and an operational amplifier 404, and when the output of the detection circuit 3 becomes lower than the comparison voltage input through the resistor 403, the output It has a comparison function to output.

The output of the determination circuit 4 is input to the input terminal of the display circuit 5. The display circuit 5, as shown in FIG. When the output of the determination circuit 4 becomes ゜1゜, the light emitting diode lights up, and furthermore, the output of the detection circuit 3 is displayed as a voltage by the analog meter 505.

In this embodiment, the high voltage cable 2 of the detection device 1 is electrically connected to the connection point between the secondary output terminal of the ignition coil IG of the high voltage circuit section of the vehicle and the coil cord CC by suitable means. The ground 6 of the detection device 1 is connected to the engine and body ground of the vehicle.

Furthermore, the synchronization signal cable 7 of the detection device 1 is electrically connected to the primary coil terminal of the ignition coil IG in the ignition circuit of the vehicle. Further, an attachment means P made of an insulating material is provided between the connection point of the plug cord PC and the ignition plug PL.
One end PC2 of the plug cord PC and the spark plug PL are connected in an electrically insulated state with the plug A interposed therebetween. The action will be explained below. In the above connection relationship, engine key S
When the engine shaft connected to the starter drive shaft is rotated by operating W to supply voltage from the battery BA to the ignition circuit and simultaneously driving a starter (not shown), the engine shaft The distributor shaft interlocked with is rotated, the interrupter PO in the distributor opens and closes, and a high voltage of several tens of K is generated in the secondary coil IG2 of the ignition coil IG. The high voltage is input to the detection circuit 3 via the high voltage cable 2, and is also supplied to the center electrode of the distributor DB via the coil cord CC.
By the rotation of the rotor B, the plug code PC of each cylinder
The high voltage is distributed and applied to. However, since the attachment means PA is interposed between the plug cord PC and the spark plug PL, the high voltage is not applied to the spark plug PL. Therefore, the engine drive shaft is only rotated by the starter, that is, cranked, and the engine is not started. In this engine cranking driving state, the high voltage generated from the secondary output terminal of the ignition coil IG is applied to the coil cord CC.
If a voltage leak occurs within the high voltage circuit section, which is applied to the high voltage circuit section consisting of the 1 distributor DB1 plug cord PC, this will be indicated by the operation of the voltage leak detection device 1. The operation of voltage leak detection device (2) will be explained in detail below.

When the engine key SW is operated to drive the engine by cranking, the primary voltage shown in FIG. The signal is then input to the waveform shaping circuit 8. The waveform shaping circuit 8 converts the primary voltage signal (FIG. 6a) into a rectangular wave (FIG. 6b) and outputs it to the next stage synchronous circuit 9. The synchronization circuit 9 receives the primary voltage signal (sixth
A reset signal (FIG. 6 d) and a sampling signal (FIG. 6 c) having a fixed time width synchronized with the rising and falling portions of FIG. 6 a) are generated and output to the detection circuit 3, respectively. The detection circuit 3 is provided with the following by the high voltage cable 2:
High voltage from the secondary terminal of the ignition coil IG (Fig. 6e)
is input, and further, by the operation of the reset signal (FIG. 6 d) and the sampling signal (FIG. 6 c), a DC signal (FIG. 6 f) indicating the maximum value of the output of the ignition coil IG is generated.
and g) to generate the DC signal in Fig. 6g,
It is output to the next stage determination circuit 4. The determination circuit 4 determines the level of the DC signal input from the detection circuit 3 based on the determination level based on the voltage leak phenomenon in the high voltage circuit section, and if it is below the determination level, that is, a voltage leak has occurred. Then, a determination signal (h in FIG. 6) is output and displayed by the next stage display circuit 5. In the above embodiment, the present invention is applied to voltage leak detection in the high voltage circuit section of the ignition system of an engine installed in an automobile, but the scope of application of the present invention is not limited to this and is applicable to general internal combustion engines. It is clear that the same applies to the ignition system of

Further, the detection circuit 3 of this embodiment detects a leak voltage signal as a leak signal based on a leak phenomenon, but the leak signal can be similarly applied even if a signal waveform change is detected. Furthermore, although the waveform shaping circuit 8 of this embodiment uses a primary voltage signal as the primary signal detected from the primary side of the ignition coil, any electrical signal that is synchronized with the primary current signal or secondary voltage signal may be similarly applied. can.

As described above, according to this embodiment, in view of the fact that the operation of the ignition coil IG is synchronized with the timing at which the center electrode and the outer electrode of the distributor DB sequentially face each other, the engine is cranked and driven. Since the ignition coil is used as a high voltage power source for leak detection, the secondary voltage of the ignition coil applied to the coil cord CC is reliably distributed and applied to each plug cord via the distributor DB, and Since leakage is detected in synchronization with the ignition coil operating signal, it is possible to reliably detect the leakage state corresponding to each plug cord.

In addition, since the plug cord and the ignition hydrant are electrically insulated, leak detection is possible even with a sufficiently high secondary voltage of the ignition coil, without being limited by the spark discharge starting voltage of the ignition hydrant. At the same time, this has the effect of eliminating the need for a special high-voltage power supply. As explained above, according to the present invention, in a state where a high voltage circuit section consisting of a coil cord, a distributor, and a coil cord is mounted in an internal combustion engine, the plug cord and the ignition plug are electrically insulated, In the engine engine ranking drive state, the ignition coil is operated to distribute and apply high voltage to the high voltage circuit section via the coil cord, and in synchronization with the operation signal of the ignition coil, a leak signal is detected and the leak status is detected. Since the leakage state is detected, it has the excellent effect of being able to reliably and quantitatively measure the leakage state without relying on the operator's sensory test.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the main parts where the high voltage generated from the ignition coil causes voltage leaks in the high voltage circuit of an engine using the high voltage ignition method. FIG. 3 is a sectional view showing the configuration of a high voltage cord constituting a circuit section. A pinhole is created in a part of the high voltage cord, and a point at a distance D from the outer diameter of the high voltage cord is connected to the conductor of the high voltage cord. A diagram showing the relationship between interval length D and leakage voltage when a high voltage is applied between them and voltage leakage occurs. FIG. 4 is a block diagram of a leakage state detection device based on an embodiment of the present invention. FIG. 5 is an electric circuit diagram showing a preferred embodiment based on the block diagram of the leak state detection device shown in FIG. FIG. 6 is a time chart showing signal waveforms of various parts of the voltage leak detection device shown in FIGS. 4 and 5. FIG. IG...Ignition coil, CC...Coil code, DB
...Distributor, PC...Plug cord, PL...Spark plug, BA...Battery, I...Leak condition detection device, 2...High voltage cable, 3...Detection circuit, 4・・・
・Judgment circuit, 5...Display circuit, 6...Earth, 8.
...Waveform shaping circuit, 9...Synchronization circuit.

Claims (1)

[Claims] 1. A coil cord connected to an ignition coil of an internal combustion engine ignition system, a distributor connected to the coil cord, a plurality of plug cords connected to the distributor, and an ignition connected to each of the plug cords. In a high voltage circuit section equipped with a plug, the high voltage circuit section is installed in an internal combustion engine, electrically insulating between the plug cord and the ignition plug, and driving the engine to crack to operate the ignition coil. An internal combustion engine characterized in that a leak state is detected by detecting and determining a leak signal based on a leak phenomenon occurring in a high voltage circuit section in synchronization with an operating signal of the ignition coil. A method for detecting a leak condition in the high voltage circuit section of an ignition system. 2 An internal combustion engine ignition system equipped with a coil cord connected to the ignition coil, a distributor connected to the coil cord, a plurality of plug cords connected to the distributor, and a spark plug connected to each of the plug cords, and A means for electrically insulating between a plug cord of a high-voltage circuit mounted in an engine and a spark plug, a processing circuit for detecting an operating signal of an ignition coil of an ignition system, and a rising portion and a falling portion of the operating signal. a synchronous circuit that generates two sets of pulse signals in synchronization with the ignition coil; a high voltage cable conductively connected to the secondary terminal of the ignition coil; a detection circuit that detects the maximum value of the secondary signal output from the ignition coil via a cable; a determination circuit that compares and determines the output signal of the detection circuit with an arbitrarily settable determination level; and an output of the determination circuit. A high voltage circuit section of an internal combustion engine ignition system, comprising a display circuit for displaying a judgment result of the above, and detects a leak state when a high voltage is distributed and applied in an engine cracking drive state. Leak status detection device.