JPS63105265A - Knocking control device for multi-cylinder engine - Google Patents

Abstract

PURPOSE:To dissolve knocking responsibly, as preventing the waste decline of power of an engine and rise of temperature of exhaust gas, by fixing the retard condition of ignition timing, when knocking of at least one cylinder is dissolved. CONSTITUTION:Knock sensors 10, 10 adapted to detect knocking, are attached to plural cylinders 1, 2 of a multi-cylinder engine, respectively. Here, when knocking of these both cylinders 1, 2 is detected, ignition timing of both cylinders 1, 2 is retarded by a controller 18. Then, when knocking of at least one cylinder is dissolved, the retard is stopped, and thick fuel-air mixture is fed to the other cylinder in which knocking is generated, by increasing the quantity of fuel. In this way, decline of engine power and rise cf temperature of exhaust gas caused by the retard of ignition timing, can be controlled to the minimum. Subsequent knocking is not so intense as it is due to dispersion of characteristics of the cylinders, and accordingly, the air-fuel ratio can be controlled at the optimum value, which is effective to dissolve the knocking, without damaging durability of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a knocking control device for a multi-cylinder engine.

(Prior art) In a multi-cylinder engine, a technology is generally known in which a knock sensor is installed in each cylinder to detect knocking, and when knocking occurs, the ignition timing of the golden cylinder is retarded to eliminate the knocking1. For example, JP-A-59-
Publication No. 3175 states that in such a knocking control device, by independently advancing the ignition timing for each cylinder after knocking is eliminated, the optimal ignition timing with less output loss is achieved regardless of variations in characteristics between cylinders. There is a description of the technology to obtain this.

On the other hand, it is generally known that knocking can be eliminated by increasing the amount of fuel to the cylinders to form a rich air-fuel mixture as a countermeasure against knocking.

(Problem to be solved by the invention) In a method for eliminating knocking by retarding the ignition timing, if the ignition timing is retarded until the knocking in the golden cylinder is eliminated, regardless of the variation in characteristics between cylinders, the knocking can be eliminated with a small retard. The amount of retard for the cylinders that are used will be more than necessary, leading to a temporary drop in output, and the exhaust gas temperature will increase due to afterburning.
There is a problem that causes deterioration of the exhaust purification device.

On the other hand, the method of eliminating knocking using the 'a mixture does not have the problems of a large drop in engine output or an excessive rise in exhaust gas temperature, but it takes time for the rich mixture to be reflected in the elimination of knocking, which means that the response is reduced. In addition to problems, there are also defects that lead to deterioration of fuel efficiency.

(Means for Solving the Problems) As a means for solving the above-mentioned problems, the present invention provides knock sensors for detecting knocking in multiple cylinders of a multi-cylinder engine, and when knocking in the multiple cylinders is detected, the ignition of the multiple cylinders is activated. A multi-cylinder engine comprising means for retarding the timing, and means for stopping the retardation when knocking in at least one cylinder disappears and supplying a rich mixture by increasing the amount of fuel to other cylinders in which knocking is occurring. The present invention provides a knocking control device.

(Function) In the knocking control device described above, when knocking occurs in multiple cylinders, the knocking is resolved with good responsiveness by retarding the ignition timing. Since the retard state is fixed when knocking in at least one cylinder disappears, the reduction in engine output and the increase in exhaust gas temperature due to this retard can be minimized.

After that, the knocking will be eliminated by controlling the air-fuel ratio of the other cylinders that are causing the knocking, but the knocking at this point is due to variations in the characteristics between the cylinders, and the intensity of the knocking will vary. It is lightweight, and therefore it is possible to control the air-fuel ratio to the optimum level effective for eliminating knocking without impairing the durability of the engine.

(Effects of the Invention) Therefore, according to the present invention, it is possible to prevent an excessive decrease in engine output and an increase in exhaust gas temperature, and to eliminate knocking that affects engine durability with good response. In addition, when there are variations in the characteristics between air heights, it is possible to relatively easily control the retard amount and air-fuel ratio of one ignition timing to optimal values effective for preventing knocking.

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

In the two-cylinder rotary piston engine shown in FIG.
The rotor housings 4, 4 are provided between the rotor housings 3c. 5 is an oil pan, 6 is a pulley, and 7 is a ring gear. Each rotor housing 4, 4 is provided with first and second spark plugs 8, 9, a knock sensor 10 that detects knocking, and a fuel injection valve 11, and each spark plug 8, 9 is connected to an igniter 12. It is connected.

The intake system includes an air cleaner 13, an air flow meter 14, a throttle valve 15, and a surge tank 16 in this order from the upstream side, and receives signals from a knock sensor 10, an air flow meter 14, and a rotation sensor 17 that detects the engine speed. is input to the controller 18, and the controller 18 outputs an activation signal to the fuel injection valve 11 and the igniter 12.

The structure around the rotor housing is shown in FIG. That is, in the same figure, 20 is a rotor supported by an eccentric shaft 21, and an intake port 2 of the rotor housing 4 is connected to the rotor 20.
2 and an exhaust port 23 are connected to an intake pipe 24 and an exhaust pipe 25. A large number of water jackets 26 and bolt holes 27 for fastening the housing are opened at appropriate intervals on the side surface of the rotor housing 4, and the knock sensor 10 is connected to a second knock sensor located on the trailing side in the rotor rotation direction. It is attached to a boss portion 28 that forms a bolt hole 27 on the trailing side of the spark plug 9 . Further, the fuel injection valve 11 is connected to the intake boat 22.
A baffle plate 29 is provided directly in front of the injection port.

The reason why the knock sensor 10 is provided on the trailing side of the second spark plug 9 is because at that position, the working chamber forms a narrow clearance where the flame propagates from the compression top dead center to the expansion stroke, making it easy for knocking to occur. It is. Further, since the knock sensor 10 is provided on the highly rigid boss portion 28, it is possible to reliably detect vibrations of the rotor housing 4 without being interfered with by the water jacket 26.

The controller 18 includes an injection amount calculation unit that calculates a basic fuel injection amount for the solid cylinders 1 and 2 based on signals from the air flow meter 14 and the rotation sensor 17, and a knock sensor 10.1.
a knock determination unit that determines the presence or absence of knocking in the solid cylinders 1 and 2 and the magnitude of the knocking intensity based on the signal from 0;
an ignition timing control section that retards the ignition timing of each cylinder 1 and 2 when knocking is detected, and when there is knocking in the solid cylinders 1 and 2, retards the ignition timing until the knocking of either one disappears; The fuel control unit is provided with a fuel control unit that increases the amount of fuel in the other cylinder in which knocking occurs until the knocking disappears to form a rich air-fuel mixture when the knocking disappears.

The flow of knocking control is shown in Figure 3. First,
The knocking signals from the knock sensors 10.10 of the solid cylinders 1 and 2 are read, and if there is knocking, it is determined whether or not there is knocking in both the solid cylinders 1 and 2 (step 8
1 to S3), if there is knocking in one cylinder, the ignition timing of that cylinder is retarded until the knocking disappears (steps S4, S5).

If there is knocking in solid cylinders 1 and 2, compare the knocking intensities, and if the knocking intensity in the first cylinder 1 is high, adjust the ignition timing of the solid cylinders 1 and 2 until the knocking in the second cylinder 2 disappears. After the knocking disappears, the amount of fuel injected into the first cylinder 1 is increased so that the mixture becomes rich until the knocking in the first cylinder 1 disappears (steps 86 to 8).
510), conversely, when the knocking of the second cylinder 2 is large.

After retarding the ignition timing of solid cylinders 1 and 2 until the knocking in the first cylinder disappears, the fuel injection amount for the second cylinder 2 is increased until the knocking disappears (steps SL1 to 514).

That is, as shown in the time chart in Fig. 4, when there is knocking in solid cylinders 1 and 2, the air-fuel ratio of the mixture for solid cylinder 1.2 remains the same, only the ignition timing is retarded, and one cylinder The retardation of the ignition timing is stopped when the knocking disappears, and if knocking continues to occur in the other cylinder after that, the air-fuel ratio of the mixture for this other cylinder is corrected to the rich side and the knocking is stopped. It will be resolved.

Therefore, according to the above-mentioned knocking control device, knocking can be eliminated with good responsiveness by retarding one ignition timing, and once knocking in one cylinder has disappeared, no further retardation will be performed, so there will be no unnecessary reduction in output or exhaust gas. A rise in temperature is prevented. Since the knocking occurring in other cylinders at that time is minor, it is possible to reliably eliminate this minor knocking by controlling the fuel injection amount without impairing the durability of the engine. .

In addition, since the control timing is different between knock control by retarding the ignition timing and fuel control, there is no hunting in the control, and in the end, the optimum retard amount and air-fuel ratio are determined from the viewpoints of engine durability, output, and exhaust gas temperature. It has good stability and can be controlled relatively easily.

Although the above embodiment relates to a rotary piston engine, it goes without saying that the present invention can also be applied to a reciprocating engine.

Further, although the above embodiment is a two-cylinder engine, the present invention can also be applied to a multi-cylinder engine with three or more cylinders.
In such a case, the ignition timing may be retarded until the knocking in two or more cylinders is eliminated to control the air-fuel ratio of the other cylinders to the rich side. Furthermore, the knock sensor may not be installed on the golden cylinder, but only on a specific plurality of cylinders. It is also possible to control knocking by providing it only in the following.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a block diagram of a knocking control device for a multi-cylinder engine, FIG. 2 is a longitudinal sectional view of the multi-cylinder engine, FIG. 3 is a control flow diagram, and FIG. It is a time chart showing the content of control. ■・・・1st cylinder, 2・・・2nd cylinder, 8
, 9... Spark plug, IO... Knock sensor, 11... Fuel injection valve 518...
·controller. Figure 1 Figure 3

Claims (1)

[Claims] (1) A knock sensor for detecting knocking is attached to multiple cylinders of a multi-cylinder engine, and means for retarding the ignition timing of the multiple cylinders when knocking is detected in the multiple cylinders, and retarding the ignition timing when the knocking in at least one cylinder disappears. 1. A knocking control device for a multi-cylinder engine, characterized in that the knocking control device for a multi-cylinder engine is provided with means for stopping the knocking and increasing the amount of fuel to supply a rich mixture to other cylinders causing knocking.