JPS6125970A - Smoking preventer for spark plug - Google Patents

Abstract

PURPOSE:To prevent a spark plug from smoking in an effective manner, by detecting size of a coil inducing signal during a period of energizing an ignition coil or an oscillating component included in the former, while setting it down to a smoking detecting signal, and operating a smoking preventer for control. CONSTITUTION:When an ignition signal is outputted out of a central processing unit 12, a power transistor 3 is set in motion via a driving circuit 11 and primary winding of an ignition coil 1 is energized with a continuous rating current, high voltage is induced in its secondary winding. At this time, if smoking occurs in a spark plug 2, a secondary current value of the ignition coil 1 increases with reduction in leak resistance, therefore an oscillating component to be superposed on the secondary current value and a secondary voltage value also decreases to some extent. Accordingly, a variation in this oscillating component is detected via a filter circuit 13, a one-shot multivibrator circuit 14, a masking circuit and an integrator 16, comparing it with the setting value with a comparator 17. And, according to output of this comparator 17, the spark plug 2 is made to be multiplicately discharged, thereby removing the smoking.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applied to a spark-ignition engine, and is equipped with a means for determining the presence or absence of smoldering of a spark plug and removing smoldering. Regarding prevention devices.

[Conventional technology]

In recent years, there has been active development of maintenance-free systems that reduce the number of man-hours during periodic inspections of vehicles such as automobiles, that is, systems that do not require maintenance or inspection or removal for that purpose.As part of such technological development, Regarding the ignition system, first of all, the spark plug itself must be of excellent quality and have a long life, as well as be reliable and especially resistant to so-called ``smolder''. In general, "1-lizburi" refers to the carbon that is generated due to continuous use at a high air-fuel ratio, etc., which adheres to and covers the ignition part of the spark plug. ), the insulation between the housing and the center electrode deteriorates and high voltage leaks through the carbon deposits, causing sparks to no longer fly in the spark gap.

If the relationship between the degree of smoldering and the insulation resistance in the spark gap is not shown, for example, if the insulation resistance is 1MΩ or less, it is completely smoldering and almost impossible to ignite.
In the case of MΩ, ignition may not occur depending on the operating conditions, and in the case of IOMΩ or more, even if there is carbon deposits, there is no problem.

Incidentally, in the above example, the reason why smoldering when IOMΩ or more is not considered to be a particular problem is that the spark plug itself has self-cleaning properties through its operation. In other words, carbon adhering to the spark plug causes the plug temperature to rise due to high operating conditions, and the self-cleaning temperature (depending on the brand of gasoline, for example, approximately 450 degrees Celsius for leaded gasoline and approximately 5 degrees Celsius for unleaded gasoline).
When the temperature exceeds 00℃~530℃, the baking will naturally break off.
be purified. In this way, the vehicle speed at which the spark plug reaches its self-cleaning temperature, that is, the self-cleaning vehicle speed, is determined by the heat value of the spark plug (which refers to the degree to which the spark plug radiates the heat it receives; the plug that radiates a large amount of heat is heated to a high temperature). (Conversely, a plug that dissipates a small amount of heat is called a low heat value.) Therefore, as one of the countermeasures when smoldering occurs, as is often practiced in the market, changing to a plug with a lower heat value is a good idea, as it lowers the self-cleaning vehicle speed and prevents carbon deposits during use. This means that there are more chances to burn out. However, by making the spark plug itself more resistant to smoldering, or by paying special attention to regular maintenance, or by improving driving techniques and proper driving operations, it is possible to make the spark plug more resistant to smoldering. Even if we try to make use of the purifying effect, there are limits to it. Therefore, as another means of solving this problem, the present applicant previously filed Japanese Patent Application No. 54-165316 (Japanese Unexamined Patent Publication No. 54-165316)
-88962). This prior invention is configured to detect the primary voltage waveform and secondary current waveform during discharging of the ignition coil in the ignition device, and perform arithmetic processing to determine the presence or absence of a clogging state and to remove it. There are high expectations regarding its usefulness. However, the smoldering detection method as in the prior invention ends up having a complicated circuit configuration and high cost, and it is also difficult to use as a smoldering removal device, especially when multiple discharges are performed. However, on the other hand, the problem is that the ignitability deteriorates.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a device for preventing smoldering of a spark plug, which solves the above-mentioned problems in the prior invention.
At that time, we focused on the fact that the pulsation status or current value of the current flowing through the ignition coil changes due to changes in the load, and we can easily and accurately detect the smoldering status of the ignition plug, and prevent the ignition plug from smoldering. or to prevent the progress of smoldering.

[Failure to solve the problem]

In order to solve the above-mentioned problems, the present invention provides an energization control means for controlling energization to the ignition coil in an internal combustion engine having an ignition coil and a spark plug connected to a secondary high voltage terminal of the ignition coil. , a detection means for detecting a voltage value or a current value induced on the primary side or secondary side of the ignition coil during the energization period, and a magnitude or magnitude of the coil induced signal in the energization direction detected by the detection means. smoldering detection means for detecting vibration components included; smoldering state determining means for determining the smoldering state of the spark plug by analyzing the smoldering detection signal; and smoldering prevention according to the output state of the smoldering state determining means. This is a smoldering prevention device for a spark plug characterized by activating a means.

〔Example〕

Embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention, and is an example in which an ignition control device is used as a smoldering prevention device. In the figure, 1 is an ignition coil, 2 is a spark plug, and 3 is a power transistor that controls the energization of the ignition coil.
4 is a detection resistor for detecting the current flowing to the ignition coil 1.

10 is the main block of the ignition control device, and the functions of each part will be explained together with the output waveform of the time chart shown in FIG. In addition, Fig. 2 (A) shows the case where there is no smoldering,
FIG. 2(B) shows the case where there is smoldering. 12 is CP
U calculates and outputs an ignition output signal (IGT signal). 11
13 is a drive circuit for driving the power transistor 3 by the ignition output signal (IGT signal) of CP (I12);
is the energizing current signal on the primary side of the ignition coil 2 [Fig. 2 (a)
14 is a coiler circuit that outputs only the high-frequency vibration component superimposed on the high-frequency vibration component [Fig. 2 (b)], and 14 is a coiler circuit that outputs only the high-frequency vibration component superimposed on 2-3) A one-shot multi-circuit 15 that emits an output signal [Fig. 2 (C)], 15 is an output signal of the coiler circuit 13, which is a high-frequency vibration component superimposed on the current flowing through the ignition coil 1. 16 is a masking circuit that selects and outputs the output signal period so that it passes through the output period and does not output noise output outside the period (Fig. 2 (d)). An integrator 17 outputs an integral output during the output period of the shot multi-circuit 14 (Fig. 2 (e)), and 17 indicates that the output voltage of the high-frequency vibration component integrated by the integrator exceeds a preset voltage value (■th). When the comparison output signal [second
(f)], and its output signal is CP
(This configuration is connected to the input port of I12.

The configuration of this embodiment is as described above, but regarding the principle of detecting the smoldering state of the spark plug in this embodiment, the operating conditions of the ignition circuit shown in FIG. 3 and the ignition circuit shown in FIG. 4 are calculated using an equivalent circuit. The results will be explained using diagrams.

In Fig. 3, 1 is an ignition coil, 2 is a spark plug, R
N is the leakage resistance that changes depending on the smoldering condition of the spark plug 2 (schematically shown as a broken line), C is the stray capacitance on the secondary side of the ignition coil (shown as a broken line), 3 is the power transistor, and 4 is the resistance to the ignition coil 1. This shows the detection resistor used to detect the conducting current.

In FIG. 3, the base terminal of the power transistor 3 (
When the IGt (hereinafter referred to as IGt) is energized (when IGt is in the old gh state), the current value flowing through the primary winding of the ignition coil 1 is (I1), and the secondary winding of the ignition coil 1 at this time is Let the value of the current flowing through the line be , ). Next, regarding the applied voltage (■2) of the spark plug 2, the leakage resistance (RN) between the spark plug 2 and the ground is set as a parameter, and FIGS.
Figure C shows the smoldering state. Figure 4A shows a state with almost no smoldering (new plug) with RN=10MΩ.
[Fig. 4A] and when RN = 1 MΩ, which represents the state in which the spark plug has started to smolder [Fig. 4B], and when RN = 1 MΩ, which represents the state in which the spark plug has progressed to smoldering and becomes difficult to ignite.
=250 Ω [Fig. 4C].

To explain in detail the detection of the smoldering state shown in FIGS. 4A to 4C, the ignition control signal (IGt) is ON (hi
oh) Then, the power transistor 3 is activated and the primary winding of the ignition coil 1 is energized. At this point, due to the transformer effect of the ignition coil, a voltage (V2 - about 2 kV) proportional to the turns ratio between the power supply voltage and the coil is induced on the secondary side of the ignition coil 1. When the spark plug 2 is not smoldering, the secondary current ■ and the secondary voltage v2 as shown in Fig. 4A are the secondary floating capacitance 1 (C) and leakage resistance (R), which are the secondary loads of the ignition coil.
Due to the effect of , the current value (I2) and voltage value (
■2) vibrates (Figure 4A). Further, the voltage oscillation (v2) on the secondary side is reversely transformed to the next side of the ignition coil, and a pulsation component is superimposed on the primary current value. However, as the smoldering of the spark plug 2 progresses, as shown in Figures 4B and 4C, the secondary current value (1) increases as the leakage resistance (RN) decreases, but at the same time the secondary current value (1) increases as the leakage resistance (RN) decreases. I2) and voltage value (v2
) also decreases, and the vibration component of the -order current (11) also decreases. - Also, as shown in Fig. 4C, when smoldering progresses, when the primary current is cut off (IGt switches from the old Oh to LOW), the secondary generated voltage of the ignition coil (
v2) decreases, and the ability to fly fire decreases.

Next, the operation of the first embodiment will be explained. For example, when the spark plug electrode temperature is low such as when the vehicle is running at low speeds or at low temperatures, the self-cleaning ability of the spark plug is low and the attached carbon cannot be burned off, or when the fuel atomization condition is poor and the spark plug is covered with fuel. In such a case, carbon adhesion to the spark plug increases and the leakage resistance value (RN) of the spark plug decreases.

At this time, as shown in Figure 4B or Figure 4C, the -order current (
The fluctuation component of I1) decreases as the leakage resistance value (RN) decreases. The ignition control circuit 10, which is configured to vary the ignition form depending on the magnitude of the vibration component superimposed on the negative current value (11), detects the smoldering state of the spark plug and performs appropriate ignition. In other words, the smoldering state of the spark plug depends on the current flowing when it is energized, as shown in Figure 2 (b).
The output of the coiler circuit 13 that detects the vibration component of 1(a),
(, b), the masking output (d) of the masking circuit 15 based on the output signal (C) of the one-shot multi-circuit 14, the integral output (e) of the integrator 16 during the masking period, and predetermined settings. 1a (V th), and when the set value or more, the comparator 17 outputs the comparison output signal (f
) is detected by emitting. If the pulsation component is large when the spark plug is new, a comparison output signal (f) is sent to the CPU 12 as shown in FIG. 4A. However, if the smoldering pulsation component of the spark plug is small, the sampling output signal ([) shown in FIG. 4B is not generated. On the other hand, the CPU 12 determines whether there is multiple discharge of the spark plug [when there is no output signal (f)] or normal single discharge of the spark plug [when there is no output signal (f)] depending on the presence or absence of the output signal (f) as shown in the flow chart shown in FIG.
(when there is).

To explain in detail the flowchart of the energization control subroutine shown in FIG. 5, step 20 is the start, and step 2 is the start.
In step 1, the output signal (f) of the comparator 17 is determined based on the presence or absence of the manually input boat signal, and in step 22.23, the determination flag corresponding to the presence or absence of the output ([) of the comparator 17 is set to '1' ( step), “o”<step).

In step 24, depending on the presence or absence of the flag, either step 25 performs multiple ignition control, or step 26 performs single discharge.
After selecting one of the ignition modes, the process returns to step 27. Here, to briefly explain multiple discharge control, for example, it is known multiple ignition control such as repeatedly performing discharge multiple times (for example, n = 5 times) in a constant cycle (for example, 3 seconds cycle) during the intake or compression process of the engine. The method is similar. Multiple discharges supply abundant ignition energy to the spark plug, burn off the carbon attached to the spark plug electrode, and change whether to perform multiple ignition or normal ignition so as to restore the smoldering of the spark plug. It's like letting them do it.

The details of the time chart of the calculation by the CPU will be omitted, but the timing for detecting the smoldering signal may be set within one shot time during the energization period, for example, at the timing indicated by the black arrow in Fig. 2(f). Of course.

The first embodiment focuses on the fact that the vibration component superimposed on the primary current (11) changes due to changes in the leakage resistance (RN) of the spark plug, and detects the smoldering state of the spark plug and detects the progress of smoldering. In this case, the ignition control device is operated to perform energization control to eliminate smoldering.

According to this embodiment, the smoldering state of the ignition plug is determined by the leakage resistance (RN) when the ignition plug 2 is in the oven during the charging period, without depending on the irregular signal when the ignition plug 2 is short-circuited during the discharging period. Since the smoldering condition is determined in a stable circuit state formed by the ignition coil 1, the smoldering condition can be detected with high accuracy. If the spark plug is smoldering, multiple discharges can be applied to the spark plug to burn out the smoldering and restore the ignition ability. Well, if there is nothing left, you can usually ignite it and avoid consuming extra energy.

Furthermore, the connection between the spark plug and the ignition coil is similarly applicable to an ignition system in which the spark plugs 2.2 are connected to both ends of the secondary terminal of the ignition coil, as shown in Fig. 6. Of course.

A second embodiment of the invention is shown in FIGS. 7 and 8. Second
The second embodiment is different from the first embodiment in the first detection means. In the Ml embodiment, the pulsating state of the secondary current value during the energization period was detected, but in this second embodiment, the pulsation state of the secondary current value flowing through the secondary winding of the ignition coil during the energization period was detected. This is to detect the pulsation state. The schematic structure thereof will be explained with reference to FIG. 7. Reference numeral 41 is a current detection resistor provided on the ground side of the secondary winding of the ignition coil 1', and is partially molded inside the ignition coil 1'. 10 is a control circuit including a smoldering detection circuit, the details of which are shown in FIG. The basic configuration except for the configuration of the secondary current value detection circuit is the same as that of the first embodiment. The operation is also the same as that of the first embodiment, so a description thereof will be omitted.

A third embodiment of the invention is shown in FIG. In the third embodiment, the resistance for detecting the secondary current in the second embodiment is replaced by the resistance value of the secondary winding of the coil. A branch section 42 is provided to detect the next voltage detection signal (v2), and the cost can be further reduced.

In this embodiment, the resistance value of the secondary current or voltage detection section may be divided by several tens to several hundreds of ohms, and it goes without saying that it should be set to a value that prevents excessive secondary generated voltage from being applied to the detection circuit section. be.

A fourth embodiment of the invention is shown in FIG. In this embodiment, the smoldering detection means is similar to the above embodiment.

In this embodiment, the secondary current value during the energization period is detected, and as shown in Figure 4, smoldering is detected by the change in the secondary current value 2 itself during the energization period due to the leakage resistance value. It was designed to do so. This will be explained using the block diagram of FIG. 10 and the time chart 1- of FIG. 11. 44
is a low-pass coiler (FIG. 11(b)) that removes pulsation of high frequency components such as noise (FIG. 11(a)). 14 One? The masking circuit of the shot multi circuit 15 has the same function as in the first embodiment. 45 is a comparator, and if the secondary current value during the energization period is larger than the set current value (V, h), it means that there is smoldering, so the output signal is changed to [Fig. 11 (C)]. 1". 46 is a hold circuit, which is connected to the one-shot signal and the comparator output signal.
A lip flop circuit is constructed so that when there is an output signal from the comparator, it is bold during one ignition period. The time chart is shown in Fig. 11 for the case where there is no smoldering of the spark plug ((B) for the case where the spark plug is smoldering. It goes without saying that the detection timing should be carried out within the hold period, and an example of the detection timing is shown by the arrow ↓ in FIG. 11(e).

The smoldering prevention device has been described above.
It goes without saying that the output signal can be used as a smoldering detector to determine the smoldering situation without removing or attaching the spark plug during periodic inspection of the mica.

An embodiment of M5 of the present invention will be explained with reference to FIG. In the above-mentioned embodiment, when the smoldering state of the spark plug is detected (as the smoldering recovery means, the control means using multiple ignitions by the ignition control device was described, but in this embodiment, the fuel injection 1 is A means for preventing the progress of smoldering of the spark plug by adjusting it according to the conditions will be explained.

Any of the embodiments described above may be used as the means for detecting the smoldering state of the spark plug. Figure 12 CA) is CP
This is a flowchart of a routine for determining the fuel injection amount of an electronic fuel injection device, etc. by detecting smoldering of U, and steps 20 to 24 are the same as the 70-chart of FIG. 5 shown in the first embodiment. It is.

If smoldering is detected in step 22, the fuel increase coefficient K is decreased by (0,7) in step 30, and if smoldering is not detected in step 23, the fuel increase coefficient K is reduced to the normal value ( 1,0) and the fuel injection amount is changed. FIG. 12(B) shows the part of step 32 in which the final injected fuel amount τ is calculated in the main routine. If the injection is smoldering, it is decreased by the value and the ignition is started. This is to prevent a large amount of fuel from landing on the plug, which will cause further damage. Of course, the calculated value f may be an increase value for correction during acceleration, etc., or may be a basic injection determined by the normal intake air amount, etc. 4. That is, according to this embodiment, fuel injection can be performed without using control means using multiple ignitions! l) Smoldering of the spark plug can be prevented by adjusting one stone.

Although the present invention has been described in detail above, in all the embodiments described above, limits are set as the smoldering detection and operating range of the spark plug according to the operating conditions, and the calculation capacity or ignition capacity of the CPU or the magnitude of the effect is limited. Of course, the detection conditions or operating conditions may be limited accordingly, such as not performing the detection when the engine is running at a high speed.

Further, as a means for preventing smoldering, it is of course possible to use control of the fuel injection amount in combination with multiple ignition control of the spark plug.

(Effects of the Invention) According to the present invention, the smoldering state of the ignition plug can be detected easily and accurately by changes in the current flowing through the ignition coil, and the smoldering state of the ignition plug can be prevented or smoldered. can prevent the progression of

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 2 is a time chart showing waveforms at various parts of the block diagram shown in FIG. FIG. 3 is a diagram showing the ignition circuit of the same embodiment. FIGS. 4A to 4C are graphs of the results of reduction using an equivalent circuit of the ignition circuit shown in FIG. 3. FIG. 5 is a control flowchart of the first embodiment. FIG. 6 is an ignition circuit diagram in which two spark plugs are applied to the first embodiment. FIG. 7 is an ignition circuit diagram of a second practical example of the present invention. FIG. 8 is a block diagram of a third embodiment of the present invention. FIG. 9 is an ignition circuit diagram of the same embodiment. FIG. 10 is a block diagram of a fourth embodiment of the present invention. FIG. 11 is a time chart showing waveforms of various parts of the block shown in FIG. 10. FIG. 12 is a control flowchart of the fifth embodiment of the present invention. (Explanation of symbols) 1...Ignition coil 2...Spark plug 4.41...Detection resistor 10...Ignition control device 11...Drive circuit 12...CPU 13...Coil motor circuit 14 ... One-shot multi-circuit 15 ... Masking circuit 16 ... Integrator 17 ... Comparator

Claims (3)

[Claims] (1) In an internal combustion engine having an ignition coil and a spark plug connected to a high voltage terminal on the secondary side of the ignition coil, an energization control means for controlling energization to the ignition coil, and a means for controlling energization on the primary side of the ignition coil during the energization period. or a detection means for detecting a voltage value or a current value induced on the secondary side; and a smoldering detection means for detecting the magnitude of the coil induced signal during the energization period detected by the detection means or the vibration component contained therein; A smoldering state determining means for a spark plug that analyzes the smoldering detection signal to determine a smoldering state of the spark plug, and a smoldering prevention means that operates in accordance with an output state of the smoldering state determining means. Smolder prevention device. (2) In the description of claim 1, the smoldering prevention means is an ignition control device, and the spark plug smoldering prevention device is caused by multiple discharges of the spark plug. (3) In the description of claim 1, the smoldering prevention means is a smoldering prevention device for a spark plug that varies the fuel injection amount of a fuel injection device.