JPS6235901Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an ignition timing control device for an internal combustion engine.

In an internal combustion engine, if the ignition timing is too early, the explosion pressure will rise during the compression stroke, causing knocking, and if the ignition timing is too late, sufficient explosion pressure will not be obtained, and in either case, the output will decrease. For this reason, ignition timing control devices have conventionally been provided that combine a centrifugal advance device that retards the ignition timing according to the engine speed and a vacuum advance device that advances the ignition timing according to the negative pressure in the intake pipe. (For example, see "Automotive Engineering Complete Book Volume 4 Gasoline Engine" published by Sankaido on July 20, 1981)
Among these, the advance angle characteristic of the centrifugal advance device is set to be near the MBT ignition timing, which produces maximum torque at full load.

However, in reality, depending on the distance traveled by a vehicle, carbon accumulates inside the combustion chamber, which increases the heat capacity within the combustion chamber and creates an adiabatic effect, further increasing the actual compression ratio. If the required ignition timing of the engine parts is maintained, as the mileage increases, the occurrence of knocking will become more severe in the high load range.

For this reason, the current situation has been to delay the ignition timing near full load from the beginning, taking into account the vehicle's service life, etc., and as a result, the torque generated by the component engine is sacrificed. Ta. Furthermore, in high compression ratio engines aimed at improving fuel efficiency, there have been problems such as a large decrease in torque for the same ignition timing retardation.

This idea was created by focusing on these conventional problems, and as the distance traveled by a vehicle increases, the optimum torque corresponding to the distance traveled can be achieved by delaying the ignition timing in the high load range of the engine. An object of the present invention is to provide an ignition timing control device for an internal combustion engine that can prevent the occurrence of knocking.

Therefore, in this invention, the ignition timing control device
ignition timing detection means for detecting ignition timing; a switching element for turning on and off the supply of ignition current to the ignition coil based on the ignition signal detected by the ignition timing detection means;
A vehicle mileage detector, an ignition timing retard circuit that retards the ignition timing in response to an increase in vehicle mileage, and an ignition timing retard circuit that enables the ignition timing retard circuit to retard in a high-load operating range set by the engine. It consists of a retard actuating means.

Embodiments of this invention will be specifically described below with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment thereof. In the figure, 1 is a battery, 2 is an ignition switch, and 3 is an ignition coil.One end of the primary coil of this ignition coil is connected to the ignition switch 2.
The other end is connected to the battery 1 through the terminal, and the other end is connected to the collector of a transistor 4, which is a switching means.
Further, the emitter of this transistor 4 is grounded, and the comparator 5 is connected to the base.

Reference numeral 6 denotes a power line connected to the ignition switch 2 and the primary coil, and a resistor 7 is connected between this power line 6 and the ground, forming a mileage detector whose resistance value increases as the mileage increases. A variable resistor 8, a variable resistor 9 whose resistance value decreases as the engine speed increases, and a resistor 10 are connected in series, and the negative input terminal of the comparator 5 is connected to the midpoint between the variable resistor 9 and the resistor 10. It is connected.

Further, 11 is a resistor, 12 is a pick-up coil as an ignition timing detection means for detecting the rotational position of the engine, and this pick-up coil 12 generates voltage by rotation of a signal rotor or the like having protrusions corresponding to the number of cylinders. The ignition signal detection transistor described later is activated. 13 and 14 are diodes. 15 is a resistor, 16 is a diode,
These are connected in series between line 6 and ground. 17 is a resistor connected between the pickup coil 12 and the cathode of the diode 16.

18 is a resistor, and 19 is a transistor. The collector of this transistor 19 is connected to the line 6 via the resistor 18, the emitter is grounded, and the base is connected to the midpoint between the resistor 15 and the diode 16. .

Further, the collector of this transistor 19 is connected to the positive input terminal of the comparator 5 via a parallel circuit of a resistor 20 and a diode 21.

22 is a switch that is closed when the engine is operated at a predetermined load or higher, and 23 is a capacitor that forms a time constant circuit together with the resistor 20, and these are connected in series between the positive input terminal and the ground. are connected to form a retard control circuit.

Further, the mileage detector including the variable resistor 8 is connected to the second
It is configured as shown in the figure.

In the figure, a gear shaft 31 is connected to a speedometer cable (not shown), and is connected to an odometer 32 via various gears. This odometer 32 is sequentially inserted into a shaft 36 from a first drum 34 that rotates integrally with a gear 33 to a sixth drum 35 having the highest number of digits.

37 is a group of gears interposed between each drum of the odometer 32. Each of these gears meshes with a gear provided on the side of each drum, and the rotation of these gears feeds and carries the numbers. ing. For example, the fifth gear 38 straddles the fifth drum 39 and the sixth drum 35 of the odometer 32, and at the same time the number displayed on the circumference of the fifth drum 39 changes from "9" to "0". It rotates and increases the number of the sixth drum 35 by 1 to perform a carry.

Reference numeral 40 denotes a traveling distance detecting section, in which a gear 42 and a drum 43 are inserted on a shaft 41.
2 is one of the gear groups 37, for example, the fifth gear 38
It meshes with. The drum 43 is integrally equipped with an elastic cam 44 and a contact piece 45 that mesh with the inner gear 42a of the gear 42, and the contact piece 45 engages with the fifth gear 38, the gear 42, and the cam 44 as the traveling distance increases. When the drum 43 rotates and comes into contact with a stopper 46, the elastic cam 44 of the drum 43 idles. Note that this contact piece 45 is connected to the variable resistor 8.
It constitutes the moving part of.

Next, we will discuss the effect.

Now, the engine is being operated, and the pickup coil 12 is turned on by the rotation of the signal rotor described above.
The ignition signal voltage Vp as shown in Fig. 3a is output, and at the timing when this ignition signal voltage Vp switches from negative to positive, the primary current i _c of the ignition coil 3 is as shown in Fig. 3b. The secondary voltage Ps generated at the time of this interruption as shown in Figure 3c is
generates a spark at the spark plug.

This series of operations will be explained in more detail as follows.

As the ignition switch 2 is turned on, the engine starts operating, and the mileage of the vehicle increases, the number on the fifth drum 39 of the odometer 32 changes from "9" to "0" and the number on the sixth drum 35 changes. When the number increases by "1", the fifth gear 38 rotates to the left accordingly. As a result, the gear 42 meshing with the fifth gear 38 rotates to the left, and the drum 43 also rotates in the same direction. As a result, the variable resistor 8
This results in an increase in the resistance value.

Here, when the engine is operating in a low load range, the switch 22 is opened and the pick-up coil 12 is opened by the rotation of the signal rotor.
A signal voltage Vp as shown in FIG. 3a is obtained. This voltage Vp causes the transistor 19 to turn on and off as shown in FIG. 3d, and in conjunction with this, the input voltage Vc of the comparator 5 changes as shown in FIG. 4e.

That is, in the negative half cycle of the voltage generated by the pickup coil 12, that is, the voltage applied to the base, the transistor is turned off as a reverse bias voltage is applied to the base. When the input voltage of the side input terminal also increases and this input voltage exceeds the power supply voltage level corresponding to the voltage division ratio of the resistor 7, variable resistor 8, variable resistor 9, and resistor 10, the base of the transistor 4 Bias voltage is applied,
This transistor 4 turns on and the ignition coil 3
A primary current i _c flows through.

Subsequently, during the positive half cycle of the voltage available at the pickup coil 12, the voltage applied to the base of the transistor 19 becomes a forward positive voltage, turning the transistor 19 on. Subsequently, the potential applied to the positive input terminal of the comparator 5 suddenly drops below the divided voltage level, and a reverse bias voltage is applied to the base of the transistor 4. Therefore, this transistor 4 is turned off, the primary current i _c is abruptly cut off, a high voltage is induced on the secondary side of the ignition coil, and a spark is generated in the ignition plug.

On the other hand, when the engine is operated above a predetermined high load range, the switch 22 is closed. In addition, in the half cycle in which the voltage Vp generated by the pickup coil 12 becomes negative, the transistor 19 is turned off, and the voltage is connected to the capacitor 2 from the line 6 via the resistor 18, the diode 21, and the switch 22.
3 is rapidly charged, and the potential of the positive input terminal of the comparator 5 also rises, transistor 4 is turned on by the forward bias from the output of comparator 5, and primary current i _c flows through ignition coil 3.

On the other hand, the voltage Vp generated by the pickup coil 12
In the half cycle in which the voltage is positive, the transistor 19 is turned on, and the voltage charged in the capacitor 23 is discharged through the resistor 20 through the collector and emitter of this transistor. For this reason,
The potential at the positive input terminal of the comparator 5 gradually decreases in accordance with the discharge time constant of the capacitor 23 and resistor 20, as shown in FIG. 3f. When the decreasing voltage level reaches the potential of the negative input terminal of the comparator 5 set by the variable resistor 8 or the like or less, the transistor 4 is turned off as shown in FIG. 3g. Therefore, after a delay of Dc, the primary current of the ignition coil 3 is cut off, and a high voltage is generated on the secondary side.

As a result, when the load is high, the comparator 5
When the positive input voltage of the comparator 5 becomes lower than the negative input voltage, the ignition timing can be delayed, and the ignition timing can be adjusted according to the negative input voltage of the comparator 5 according to the above-mentioned voltage division ratio, that is, the traveling distance. It can be shifted depending on the size of the variable resistor 8. In other words, by gradually increasing the variable resistance 8 as the vehicle continues to travel, the ignition timing can be gradually delayed.

In this embodiment, when the engine is operated at high speed, knocking is relatively unlikely to occur, so the variable resistor 9 that changes depending on the engine speed is used.
By providing this, the amount of retardation depending on the mileage is reduced as the engine speed increases.

Figure 4 is a graph showing the retardation amount with respect to the engine speed for each mileage, and the curve X is the distance traveled.
The trace knock required ignition timing for 10,000km is the same for curve Y and 30,000km, and the same for curve Z.
The trace knock ignition timing for 50000km is shown.

In this way, when the engine is operated in a high load range, the ignition timing is automatically and gradually delayed according to the mileage of the vehicle. Torque sacrifice can be eliminated. Furthermore, the occurrence of knocking can be suppressed, and as a result, fuel efficiency can be improved.

In addition, since knocking is less likely to occur before the engine is warmed up, the sensor switch that detects the cooling water temperature is connected to the variable resistors 8 and 9, or the switch 22.
By connecting this cooling water temperature in series with the engine, the ignition timing can be retarded using this cooling water temperature as one element that indicates the engine operating state.

As explained in detail above, according to this idea,
The ignition timing can be automatically and gradually retarded in response to an increase in the mileage of the vehicle, that is, an increase in the amount of carbon deposits in the engine.
In addition to maximizing the engine's inherent torque, it also provides effects such as effectively preventing knocking.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing the ignition timing control device for an internal combustion engine according to this invention, Figure 2 is an exploded perspective view of the mileage detector, Figure 3 is a time chart of signals in each part of the circuit, and Figure 4 is a trace diagram. FIG. 4 is a characteristic diagram of knock-required ignition timing. 3...Ignition coil, 4...Switching element,
8... mileage detector, 12... ignition timing detection coil, 20, 23... ignition timing delay circuit,
22...Switch.

Claims (1)

[Scope of utility model registration request] An ignition timing detection means for detecting ignition timing, a switching element for turning on and off the supply of ignition current to the ignition coil based on the ignition signal detected by the ignition timing detection means, and a vehicle mileage detector; Consisting of an ignition timing retard circuit that retards the ignition timing in response to an increase in vehicle mileage, and a retard operation means that enables the ignition timing retard circuit to retard the ignition timing in a set high-load operating range of the engine. An ignition timing control device for an internal combustion engine, characterized in that: