JPS58133478A - Ignition device of engine - Google Patents

Abstract

PURPOSE:To prevent overruns by delaying the ignition timing when actual number of revolutions is larger than the target number of revolutions corresponding to the amount of accelerator operation. CONSTITUTION:A differential amplifier 23 compares a signal representing the actual number of revolutions of an engine given from a rotation sensor 18 with a signal from a number-of-revolutions determination circuit 22, which calculates the target number of revolutions corresponding to the amount of accelerator operation given by an accelerator sensor 10, and outputs a signal according to the difference between these two. When the actual revolutions becomes higher than the target value, the ignition timing is delayed. Thus overruns can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention supplies an air-fuel mixture into a cylinder through an intake passage during an engine's intake stroke, while supplying a part of the air-fuel mixture in the cylinder to the intake passage during an engine's compression stroke. The present invention relates to an ignition device for an engine that adjusts the amount of air-fuel mixture filled by refluxing the air-fuel mixture.

In general, in engines that are equipped with a throttle valve in the intake passage and whose intake air filling amount is controlled by opening and closing the throttle valve, high intake negative pressure occurs during the intake stroke, especially at low loads when the throttle valve tends to close. occurs,
Due to this negative intake pressure, the downward movement of the piston becomes negative work, causing a loss called pumping loss.
This decreases the fuel efficiency and becomes a fundamental obstacle in trying to improve fuel efficiency.

Therefore, conventionally, JP-A No. 62-/J-277 or JP-A No. 56-t? 7/, 5 @ Publication, during the intake stroke of the engine, the air-fuel mixture is supplied into the cylinder through the intake passage without generating a large intake negative pressure, while closing later than the intake valve 1 (fl valve By providing an intake recirculation passage that is opened and closed by the engine, or by delaying the closing timing of the intake valve, part of the air-fuel mixture supplied into the cylinder during the compression stroke of the engine is returned to the intake passage. Engines have been proposed in which pumping losses are reduced by adjusting the filling amount.

However, in the above-mentioned proposed engine, when the air-fuel mixture in the cylinder recirculates to the intake passage, due to the throttling effect of the recirculation valve or the intake valve, at high engine speeds, the recirculation rate is lower than at low speeds even if the valve opening is the same. Since the flow rate is reduced and the filling amount is increased, the actual engine rotational speed becomes higher than the rotational speed corresponding to the throttle operation amount, that is, the engine output. Therefore, there is a problem in that the engine rotational speed increases rapidly with respect to the throttle operation amount, resulting in an overrun condition, which adversely affects drivability.

In other words, in a general engine that has a throttle valve in the intake passage, due to the throttling effect of this throttle valve, even if the throttle valve is at the same opening, as the engine speed increases, the amount of fuel per revolution decreases. The engine speed is stabilized at a predetermined speed.
In the case where the filling amount is adjusted by the reflux #ij system as described above, on the contrary, the filling amount per revolution/rotation, that is, increases per time, resulting in an overrun state.

In view of this, the present invention provides an engine ignition system that is equipped with an ignition timing control device that delays the ignition timing when the actual engine speed is higher than the engine speed set in accordance with the amount of accelerator operation. This is intended to prevent the occurrence of an overrun condition by suppressing the increase in engine speed.

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

In the engine shown in the first cause, 1 is a cylinder equipped with a piston 2, 3 is an intake passage that is equipped with a carburetor 4 (without a throttle valve) and communicates with a 1 pumping boat 6 that opens into a combustion chamber 5 of cylinder 1. , 7 is an intake valve that opens and closes the intake boat 6 at a predetermined timing (see Fig. 2) by a timing cam 8;
Reference numeral 9 denotes a recirculation amount control device that adjusts the closing timing of the intake valve 7 according to the operating condition and controls the intake passage flow rate. At the same time, during the compression stroke, part of the air-fuel mixture in the gas/oil 1 is returned to the intake passage B to adjust the filling amount of the intake narrow air.

The recirculation amount control device 9 receives the accelerator operation amount signal detected by the accelerator sensor 10, calculates the closing timing of the intake valve 7 according to the driving state, and operates the timing cam 8, which is a three-dimensional cam. The intake valve 7 is opened and closed at predetermined timing to control the flow rate, and the recirculation flow rate is controlled to decrease as the amount of accelerator operation increases.

That is, as shown in Figure 2, when the accelerator operation amount is maximum, the intake valve 7 is closed early as shown by curve A to reduce the recirculation amount and increase the filling amount, while when the accelerator operation amount is the minimum, the intake valve 7 is closed early as shown by curve A. The valve 7 is closed late as shown by curve B to increase the reflux amount and reduce the filling amount.

Further, in FIG. 1, reference numeral 11 denotes an exhaust passage for discharging exhaust gas through an exhaust port 12 opened into the combustion chamber 5;
1 is an exhaust valve that opens and closes the exhaust port 12 at a predetermined timing (see Figure 2) using a timing cam 14; 15 is a spark plug; 16G-! This is an ignition timing control device that controls ignition timing.

In the middle of the intake passage 3, a chamber 3a is formed in a bulging manner so that the air-fuel mixture recirculated from the cylinder 1 does not flow back into the carburetor 4.

The ignition timing control device 16 receives a load signal detected by the load sensor 17, an accelerator operation signal detected by the accelerator sensor 10, and an engine rotation speed signal detected by the rotation sensor 18, and basically adjusts the ignition timing based on the load signal detected by the load sensor 17. The ignition timing is controlled to compensate for fluctuations in L, while the ignition timing is controlled to be delayed when the actual engine speed is higher than the engine speed (upper limit) set in accordance with the accelerator operation amount.

Next, FIG. 3 shows a specific example of the ignition timing control device 16, in which a basic retard amount (ignition timing) 19 is set in response to a load signal from a load sensor 17 that detects the load from the engine Φ exhaust [f]. The output signal of the arithmetic circuit 19 is output to the igniter 24 via the correction circuit 20 and the drive circuit W121. Also, 22 is the accelerator sensor 1
Engine standard 1 after receiving accelerator operation amount signal from 0
A rotation speed determination circuit 23 that calculates the rotation speed compares the standard rotation speed signal from the rotation speed determination circuit 22 and the actual engine rotation speed signal from the rotation sensor 18, and outputs a signal according to the difference between the two. The output signal of the differential amplifier 23 is input to the correction circuit 2o, and the output signal of the differential amplifier 23 is input to the correction circuit 2o (
The addition circuit) corrects the basic retard amount signal (increases the retard amount as the load increases) from the arithmetic circuit 19 with the signal from the differential amplifier 23 (when the engine speed exceeds the standard speed). The ignition retard amount (ignition timing) is determined by increasing the retard amount during running, and the drive circuit 21 outputs a corresponding control signal to the igniter 2.4.

The igniter 24 receives the reference signal from the signal generator 25 and operates the transistor 26 at a predetermined ignition timing corresponding to the retard amount signal from the drive circuit 21: ignites the high voltage generated by the ignition coil 27. The plug 15 is used to cause discharge. 28 is an ignition switch, and 29 is a battery.

Therefore, the intake air recirculation amount that adjusts the filling amount is controlled in accordance with the accelerator operation amount, and decreases as the accelerator operation amount (load) increases, thereby increasing the intake air filling amount. On the other hand, when the engine speed increases even with the same amount of accelerator operation and the actual engine speed (〃) becomes higher than the engine speed corresponding to this amount of accelerator operation, the ignition timing is delayed and engine output is suppressed, resulting in an overrun condition. The occurrence of 1
111 Stop.

However, the present invention is not limited to the configuration of the above embodiment, but includes various modifications. In other words, the amount of ignition retardation at the time of overrun is determined by comparing the engine speed corresponding to the amount of accelerator operation with the actual engine speed and depending on the difference between them, and also by adjusting the amount of ignition retard when the amount of accelerator operation is constant. The control may be performed in response to the rate of increase in the engine speed, and map control may be used instead of using the differential amplifier 26. Regarding the fuel supply method, an injection method may be adopted instead of the carburetor method, and regarding the mechanism for adjusting the recirculation amount, various known mechanisms can be appropriately adopted as the valve closing timing variable mechanism of the intake valve 7. Furthermore, in the above embodiment, the closing timing of the intake valve 7 is made variable to adjust the recirculation amount.
Instead, an intake recirculation passage is provided separately that communicates the combustion chamber 5 and the intake passage 3, and this intake recirculation passage is opened and closed by a recirculation valve that closes later than the intake valve 7, thereby making the closing timing of the recirculation valve variable. Alternatively, an on-off valve may be provided in the intake air recirculation passage to adjust the amount of recirculation.

Furthermore, a deceleration shutter that closes during deceleration may be provided in the middle of the intake passage 6, and intake negative pressure may be generated during deceleration to apply engine braking. Furthermore, the technology of the present invention can also be applied to rotary piston engines.

As explained above, the device of the present invention delays the ignition timing and suppresses the engine output when the actual engine speed is higher than the engine speed set in accordance with the accelerator operation amount. Since it is possible to prevent the number from increasing and the occurrence of an overrun condition, the pumping loss reduction function can be fully demonstrated without impairing drivability, and it is possible to improve fuel efficiency. .

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram;
FIG. 2 is a curve diagram showing the valve opening/closing timing, and FIG. 3 is a block diagram showing a specific example of the ignition timing control device. 1...Cylinder, 3...Intake passage, 4.
... Carburetor, 7 ... Intake valve, 8 ... Timing cam, 9 ... Speed flow control device, 10 ... Accelerator sensor, 15 ... Spark plug, 16 ... One point Fire timing control device, 17...load sensor, 18...
... Rotation sensor, 19 ... Arithmetic circuit, 2
0... Correction circuit, 21 drive circuit, 22...
...Rotation speed determining circuit, 23...Differential amplifier, 24...
...Igniter, 25...-Signal generator, 26...
・Transistor, 27 ・Ignition coil

Claims (1)

[Claims] (1) During the intake stroke of the engine, the air-fuel mixture is supplied into the cylinder through the intake passage, while during the compression stroke of the engine, part of the air-fuel mixture in the cylinder is recirculated to the intake passage, and the amount of recirculation is In an engine in which the amount of air-fuel mixture is controlled by adjusting it according to the operating condition of the engine, the ignition timing is determined when the actual engine speed is higher than the engine speed set according to the amount of accelerator operation. An ignition device for an engine, characterized in that it is provided with an ignition timing control device that delays the ignition timing.