JPS5848779A - Method of restraining generation of knocking in spark ignition type engine - Google Patents

Abstract

PURPOSE:To prevent knocking surely by a method wherein a knocking restraining agent is supplied into a combustion chamber for the engine in case the knocking is being generated even when ignition timing is delayed to a predetermined angle upon generation of the knodking. CONSTITUTION:When the ignition timing is smaller than the amount of the maximum delayed angle thetamax upon generating the knocking, the feedback control of the ignition timing is effected as it is. On the other hand, when the ignition timing is arrived at the amount of the maximum delayed angle thetamax, the ignition timing is set at the maximum delayed angle thetamax and water injection for the combustion chamber is begun.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for suppressing the occurrence of knocking in a spark ignition engine used in vehicles such as automobiles.

Generally, in a spark ignition engine, so-called knocking, which generates large vibrations and knocking noises, may occur due to rapid combustion of end gas. This knocking becomes more likely to occur as the compression ratio of the engine increases, and in engines that are supercharged by a turbocharger, it is particularly likely to occur during full load operation.

For this reason, in spark ignition engines that are supercharged,
It has been considered to reduce the advance angle of the ignition timing when knocking occurs. However, if the ignition timing advance angle decreases, the thermal efficiency of the engine will decrease, and the concentration of exhaust gas will increase, which may have an undesirable thermal effect on the turbocharger. There is a limit to the degree to which the angle can be reduced. In many cases, knocking can be effectively prevented without reducing the ignition timing advance angle to its eye limit value, but this may be due to variations in the engine's mechanical octane number, atmospheric pressure, concentration, humidity, etc.
Even if the advance angle of the ignition timing is reduced to its limit value due to a change in the l11 condition, the occurrence of knocking may not be suppressed. One way to prevent this is to lower the engine's compression ratio, but if the compression ratio is lowered, the engine's output performance will decrease, and the engine's output will be lower when knocking is not occurring. Performance will not be fully demonstrated.

An object of the present invention is to provide a method for suppressing the occurrence of knocking in a spark ignition engine without causing any adverse effects such as a reduction in engine output performance.

According to the present invention, the purpose is to detect knocking by a knocking sensor, and to reduce the advance angle of the ignition timing when knocking is detected by the knocking sensor, and to reduce the advance angle of the ignition timing to a predetermined value. a second step of supplying a knock suppressant such as water to the engine III combustion chamber without reducing the advance angle beyond a predetermined value when knocking is detected by the knocking sensor even though the knocking has been reduced to a predetermined value; This is achieved by a method for suppressing the occurrence of knocking in a spark ignition engine.

The present invention will now be described in detail with reference to the accompanying drawings.
explain.

FIG. 1 is a schematic configuration diagram showing one embodiment of a suitable spark ignition engine in which the method for suppressing the occurrence of knocking according to the present invention is implemented. In the figure, 1 indicates an engine, and the engine 1 has a cylinder block 2 and a cylinder head 3. The cylinder block 2 receives a piston 4 in a cylinder pore formed inside the cylinder block 2, and the piston A combustion chamber 5 is defined above the combustion chamber 4 together with the cylinder head.

An intake boat 6 and an exhaust port 7 are formed in the cylinder head 3, and these boats are opened and closed by an intake pulp 8 and an exhaust pulp 9, respectively. Also, a spark plug 10 is attached to the cylinder head 3,
The spark plug 10 is supplied with current generated by the ignition coil 11 via a distributor 12, and generates sparks by discharging within the combustion chamber 5.

- The air port 6 includes an intake manifold 13, a surge tank 14, a throttle body 15 with a throttle valve 16, a compressor housing 31 of a turbocharger 30, and an intake! 17, a connecting tube 118, an air 70-meter 19, and an air cleaner (not shown) are connected in this order, and these constitute the intake system of the engine. A fuel injection valve 20 is attached near the connection end of the intake manifold 13 to the intake boat 6. The fuel injection valve 20 is supplied with liquid fuel such as gasoline stored in a fuel tank (not shown) by a fuel pump through a fuel supply pipe, and its opening time is controlled by a signal generated by a control device 50, which will be described later. The fuel injection amount is metered and controlled.

An exhaust manifold 21 and a turbine housing 32 of a turbocharger 30 are connected to the exhaust port 7 .

The turbocharger 30 has its compressor housing 3
1 has a compressor wheel 33, which is connected by a shaft 34 to a turbine wheel 35 installed in the turbine housing 32, and which is connected to the turbine wheel 35 by the pressure of the exhaust gas discharged from the engine 1. By rotating the compressor wheel 33, the compressor wheel 33 rotates once, and the engine 1 is supercharged with intake air. Further, the turbine housing 32 is provided with a bypass passage 36 that bypasses a portion where the turbine wheel 35 is disposed, and this bypass passage 36 is selectively opened and closed by a bypass valve 37.

The diaphragm @W394m is connected via the bypass valve 37 & the t-link 138, and is driven by the diaphragm device. Diaphragm device 39&t
The intake pipe pressure of the engine 1 is introduced into the diaphragm chamber (not shown) through a conduit 40, and when the intake pipe pressure exceeds a predetermined value determined based on the durability of the engine 1, the bypass valve 37 is opened and bypassed. The passage 36 is opened.

Further, a water injection valve 41 is attached to the surge tank 14. The water injection valve 41 injects water (
A knocking suppressing liquid (such as alcohol or a filtrate of water and alcohol) is supplied through a conduit 43, a pump 44, a conduit 45, a constant pressure valve 46, and a conduit 47, and is supplied to a control device 5, which will be described later.
The valve opening time is controlled by the signal generated at 0, thereby controlling the water injection amount.

Controller 50 may be a conventional microcomputer, an example of which is best shown in FIG. This microcomputer 50 has a central processing unit (CPU)
51ε, read-only memory (ROM), 52, random access memory (RAM) 53, and input port @
854 and an output boat device 55, which are connected to each other by a bidirectional humon bus 56.

The input port device 54 receives an air flow number generated by the air flow meter 19, a cylinder discrimination signal and a crank rotation angle signal generated by a cylinder discrimination sensor 48a and a rotation angle sensor 48b attached to the distributor 12, and a cylinder/dub. A knocking detection signal generated by a knocking sensor 49 attached to the engine 2 is inputted, and these data are appropriately converted into signals and output to the CPU and RAM 53 according to instructions from the CPU 51.

The CPU 51 adjusts the fuel injection timing, ignition timing, water injection timing, and water injection amount based on the data detected by each sensor according to a program stored in the RAM 52,
The fuel injection signal sent thereto is sent to the fuel injection valve 20, the ignition timing signal is sent to the igniter 22, and the water injection signal is sent to the water injection valve 4.
1 from the output port device I55.

A. The igniter 22 is attached to the ignition cobble 11 as shown in FIG. It is designed to block the road and control the advance angle of the ignition timing.

The manner in which the control method of the present invention is implemented will be explained below with reference to the flowchart shown in FIG.

This routine is performed for each stroke of the engine, and in the first step 1, the engine rotation speed calculated based on the crank rotation angle measured by the rotation angle sensor 48b and the air 70-meter 19 are calculated. Data on the amount of intake air and the level of occurrence of knocking detected by the knocking sensor 49 are read. In the next step 2, the iris advance angle equation θa is determined based on the engine speed and intake air amount.

In the next step 3, it is determined whether or not knocking occurred during the previous engine stroke. If knocking has occurred in the previous engine stroke, in order to reduce the advance angle in step 4, the previous corrected advance angle θ determined by the previous routine and stored in the RAM 53 is A calculation is performed to add Δθ to 1, and a new corrected advance angle θ' is calculated.Next, in step 5, it is determined whether the corrected advance angle θ' is smaller than the advance angle reduction eye-field value θ-aX. A determination is made. When θ"≦θ-aX, the process proceeds to step 6; however, when θr≦θ-a×, that is, when the corrected advance angle is larger than the advance angle reduction eye-field value, step 8
In step 9, the corrected advance angle θ' is set to the eye limit value θ−aX, and in step 9, water injection by the water injection valve 41 is started.

On the other hand, knocking occurred during the previous process.

If not, in step 10 it is determined whether or not knocking has occurred in the previous 10 strokes. If knocking has not occurred in the previous 10 engine strokes, then in step 11 it is determined whether or not water injection is in progress.If water injection is not in progress, the process advances to step 14 and A calculation is performed to subtract Δθ from the modified advance angle θ·rH, and a new modified advance angle θr is calculated. When it is determined in step 11 that water is being injected, the process proceeds to step 12, where the water injection by the water injection valve 41 is stopped, and the process proceeds to step 13. Also, when the state in which no knocking occurs is less than 10 strokes, the process proceeds to step 13 and the previous corrected advance angle θrH-θ is set.

As described above, once the corrected advance angle θ'' is calculated, in step 6, the previous corrected advance angle stored in the RAM 53 is rewritten to θr, and the previous corrected advance angle θr is rewritten to the new corrected advance angle θr.

In the next step 7, the following calculation is performed: (basic advance angle θa) - (modified advance angle θ''), and the executed advance angle θ is calculated, which is stored in the RAM 53. If it is zero, the execution advance angle θ is equal to the basic advance angle θa, and if the modified advance angle θ is greater than zero, the execution advance angle θ is equal to the basic advance angle θa.
decreases from the basic advance angle θa, that is, the advance angle becomes smaller.On the other hand, if the modified advance angle θ'' is smaller than zero, the actual advance angle θ increases than the basic advance angle θa, that is, the advance angle becomes large.

The ignition timing signal is transmitted to the igniter 22 at a predetermined time determined according to the actual advance angle θ determined in the manner described above, the cylinder phase detected by the cylinder phase discrimination sensor 48a, and the crank rotation angle detected by the rotation angle sensor 48b. Output to.

As is clear from the above explanation, according to the method of the present invention, when knocking is detected by the knocking sensor, the advance angle of the fire rate is reduced, and even if the advance angle is reduced to the limit value. However, if knocking is still detected by the knocking sensor, the water injection valve is operated while keeping the advance angle at the eye limit value, and water, alcohol, or a mixture thereof is injected into the surge tank. , and is supplied to the ms room together with the intake air. When water, alcohol, or a mixture thereof is supplied into the engine combustion chamber in this manner, the octane number is improved by 0.0 degrees, and the occurrence of knocking is avoided even if the ignition timing advance angle is not further reduced. This water injection is carried out only when knocking is extremely severe, when knocking occurs even though the ignition timing advance angle has been reduced to the limit value, so the knocking suppressant such as water is consumed. The amount can be saved and the storage tank can be made smaller, which makes water injection more effective in vehicle engines. The water injection sac may be set according to the intake air amount per stroke of the engine, and this may be controlled in the same manner as the fuel injection amount Mill, and the signal for controlling the fuel injection amount may be set separately. It's okay to be.

Although the present invention has been described in detail with respect to specific embodiments above, it will be understood by those skilled in the art that the present invention is not limited thereto and that various embodiments can be made within the scope of the present invention. It would be obvious for

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of a spark ignition engine suitable for carrying out the method of suppressing knocking according to the present invention, and FIG. 2 is a block diagram showing an example of a control device implementing the method of the present invention. 3 are flowcharts showing the routine of the control device implementing the method of the present invention. 1...Engine, 2...Cylinder block, 3...
・Cylinder head, 4... Piston, 5... Combustion chamber, 6... Intake port, 7... Exhaust boat, 8...
Intake pulp, 9... Exhaust pulp, 10... Spark plug, 11... Ignition coil, 12... Distributor, 13... Intake manifold, 14... Surge tank, 15... Throttle body , 16... Throttle valve, 17... Intake pipe, 18... Connection tube, 19... F70-meter, 20... Fuel injection valve, 21... Exhaust manifold, 22... Igniter, 30...turbocharger. 31... Compressor housing, 32... Turbine housing, 33... Compressor wheel, 34
... shaft, 35 ... turbine wheel, 36 ... bypass passage, 37 ... bypass valve, 38 ... link element, 39 ... diaphragm device, 40 ... conduit,
41... Water injection valve, 42... Tank, 43... Conduit, 44... Pump. 45-- Conduit, 46-- Constant pressure valve, 47-- Conduit,
48a... Cylinder discrimination sensor, 48b... Rotation angle sensor, 49... Knocking sensor, 50... Control device (microcomputer), 51... Central processing unit (CPU), 52... Lead Only memory (ROM)
), 53...Random access memory (RAM), 5
4...Input port II! , 55... Output port device, 56... Common bus

Claims (1)

[Claims] a first step of detecting knocking by a knocking sensor; - reducing an ignition timing advance angle when knocking is detected by the knocking sensor; a second step of supplying a knock suppressant such as water to the engine combustion chamber without reducing the advance angle beyond a predetermined value when knocking is detected by the knock sensor. A method for suppressing knocking in a type engine.