JPS58107863A - Control method of knocking in internal-combustion engine - Google Patents

Abstract

PURPOSE:To efficiently perform knocking control with a knock suppressing agent, by supplying a prescribed amount of the knock suppressing agent to an engine when an operational condition of the engine is decided in a knocking generation range from detected operational condition parameters. CONSTITUTION:A solenoid injection valve 16 for a knock suppressing agent of water, alcohol, etc. is mounted to a surge tank 14 provided in the downstream of a throttle valve 10 in an intake passage 12, and the knock suppressing agent in a tank 18 is supplied to said valve 16 by a pump 20. The valve 16 is controlled opening and closing by a control circuit 24, and each output of a throttle sensor 28, water temperature sensor 32 and crank angle sensor 38 is input to the circuit 24. Then the present operation range is decided whether in a knocking operation range or not in said circuit 24 by using a map in a memory from an engine speed and throttle opening, if the knocking operation range is decided, the valve 16 is controlled opening to inject a fixed amount of the knock suppressing agent for a time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for suppressing knocking in an internal combustion engine.

When the compression ratio of an engine is increased in order to improve its fuel efficiency, knocking often occurs when the throttle valve is wide open, especially in low to medium speed ranges. Therefore, in high compression ratio engines, turbocharged engines, etc., the ignition timing is delayed in the operating range described above to suppress the occurrence of knocking. However, according to such a suppression method, the operating characteristics such as the torque percentage of the engine are deteriorated, and as a result, even if the fuel efficiency is improved, the problem arises that the operating characteristics are deteriorated.

As a method to suppress the occurrence of knocking without delaying the ignition timing, the area where knocking is unlikely to occur (
There is a known method for supplying a knock suppressant to an engine when knocking occurs (hereinafter referred to as knocking). In this type of conventional method, a discharge port for the knock suppressant is provided in the venturi part of the capretor, and the knock suppressant is discharged into the intake passage by the negative pressure of the venturi. Therefore, the supply amount is approximately equal to the intake air flow rate. It was proportional. That is,
According to the prior art, the ratio between the amount of knock suppressant supplied and the amount of fuel supplied was constant regardless of the engine rotational speed and the like. However, in reality, it is desirable to change the ratio between the amount of knock suppressant supplied and the amount of fuel supplied depending on the height of the engine's rotational speed. If this is not done, excess knock suppressant may be supplied and the Knocking suppression control may be performed, or knocking may occur due to insufficient supply of knock suppressant. Since the amount of knock suppressant installed in a vehicle is limited, excess consumption is naturally undesirable.

Therefore, the present invention solves the above-mentioned problems of the prior art, and its purpose is to provide an efficient knock control method using a knock suppressant.

A feature of the present invention that achieves the above-mentioned object is that when it is determined that the operating state of the engine is in a predetermined region where knocking is considered to occur, the operating state of the engine is detected. The aim is to supply the engine with a constant amount of knock suppressant over time.

The present invention will be explained in detail using the following drawings.

FIG. 1 schematically shows, as an embodiment of the present invention, an example of an internal combustion engine in which the occurrence of knocking is suppressed by supplying a knock suppressant and the ignition timing is advanced to improve the operating characteristics of the engine. It is shown. In the figure, 10 is a throttle valve provided in the middle of an intake passage 12 of the engine. An electric or magnetic injection valve 16 for a knock suppressant is attached to the surge tank 14 downstream of the throttle valve 10.

The injection valve 16 is connected to a conduit 22 through which a knock suppressant, such as water, alcohol, or a mixture of water and alcohol, filled in a tank 18 is pressurized by a pump 20.
applied via. Note that 24 is a pressure regulating valve for keeping the applied pressure of the knock suppressant constant. Injection valve 16
When a predetermined injection signal is applied from the control circuit 24 via the spinner 26, the above-mentioned pressurized knock suppressant is injected into the surge tank 14 continuously or intermittently.

The rotation shaft of the throttle valve 10 has this throttle valve 10
Throttle sensor 28 that generates electricity and pressure according to the opening degree of
is attached, and its detected voltage is sent to the control circuit 24 via line 30.

A water temperature sensor 32 that generates electricity and pressure according to the temperature of the cooling water is attached to the cylinder block of the engine, and its output -4 pressure is sent to the control circuit 24 via a line 34.

The engine's tissue distributor 36 is provided with a crank angle sensor 38 that generates a negative star position signal each time the tissue distributor shaft 36a rotates by a predetermined angle, for example, 30' in terms of crank angle. It is being The angle signal from the crank angle sensor 38 is sent to the control circuit 24 via i4o.

From the control circuit 24, a rotten flame is sent to the igniter 44 via a line 42, and the igniter 44 thereby controls energization and interruption of the primary current of the ignition coil 46. The high voltage secondary current obtained from the ignition coil 46 is sent to the small spark plug 48 via the distributor 36.

FIG. 2 is a block diagram showing an example of the control circuit 24 shown in FIG.

The output pressures from the throttle center 28 and the water temperature sensor 32 are sent to an A/D converter 50 having an analog multiplexer function, and are converted into binary signals in sequence or in a specified order at a predetermined conversion cycle.

The angle signal for every 30° crank angle from the crank angle sensor 38 is sent to the speed signal forming circuit 52, and further,
The central processing unit f (CPtJ) is used for the crank angle synchronization interrupt signal.
)54. This speed signal forming circuit 52 is
A gate that is opened and closed by the above-mentioned signal every 30 degrees of crank angle, and a clock generation time 1 that passes through this gate.
56 to form a binary continuous signal having a function dependent on the rotational speed of the engine.

From the CPU 54 via the bus 58, the output port 00
When an injection instruction signal of, for example, 1° is applied to a predetermined position, the drive circuit 62 generates a rectangular waveform injection signal having a constant tuteity ratio, and generates a rapid continuous injection signal having a constant rate of 1°. It is sent to the injection valve 16 via. As a result, the injection valve 16 discharges a constant amount of knock suppressant into the surge tank 14 over time, completely regardless of the operating state of the engine.

The small flame control circuit 64 calculates the sum to the ignition coil 46 by the CPU 54 using a well-known method.

Two registers each receive output data regarding the start time and output data regarding the end of energization time, that is, ignition timing, via bus 58, and two registers each generate a trigger pulse at the time indicated by each output data. It includes a presettable down counter and a flip-flop which is reset by the above-mentioned trigger pulse from the down counter and generates an ignition signal representative of the period to be added to the ignition coil. This type of fire control circuit is well known, and the formed Chinese signal has the same function as the device circuit consisting of the small spark plug 48, the air distributor 36, the ignition coil 46, etc. shown in FIG.
The PU 54 side may execute the process using software.

The A/D converter 50, the continuous signal forming circuit 52, the output boat 60, and the ignition control circuit 64 are connected to a CPU 54, which is a component of a microcomputer, and a read-only memory (R
OM) 6 B, Random access memory IJ (RAM
) 70 and the cross signal generating circuit 56 via a bus 58, and data is transferred via the bus 58.

Although not shown in FIG. 2, the microcomputer is provided with an input/output control circuit, a memory control circuit, etc. in a well-known manner.

The ROM 68 stores in advance a main processing routine program to be described later, a well-known interrupt processing program for calculating ignition timing, and various data, maps, tables, etc. necessary for these calculations.

Next, the processing contents of the above-mentioned microcomputer will be explained.

The CPU 54 executes the process shown in FIG. 3 during its main processing routine. First, in step 80, A
The R
The data regarding the rotational speed N stored in a predetermined area of the AM 70 is input.

In the next step 81, the cooling water temperature [THW is TH
It is determined whether W≧50°C.

If THW<50°C, the process proceeds to step 82, where the knock suppressant injection instruction flag is set to 0'').If the injection instruction flag is OFF, no injection instruction signal is output to the output boat 60, and therefore The knock suppressant is not injected. In this case, the lighting timing advance correction operation described below is not performed, and the ignition timing remains at the basic advance value. THW≧5
If the temperature is 0°C, proceed to step 83 and check that the rotation speed is 1iN.
It is determined whether or not it is 40.0 Orpm. N) 40
In the case of 00 rpm, the process proceeds to step 82 described above, but if N≦
400.

In the case of rpm, the process advances to step 84. In step 84, it is determined from the rotational speed IN and throttle valve opening θTH at that time, using a map in the ROM 68, whether or not the current operating range is a knocking operating range. If 4Li in Figure 4 is on the upper side, that is, on the high load side, it is determined that it is within the non-king occurrence area and therefore within the injection area, and the process proceeds to step 85, where the injection instruction flag is set to A ("1").
shall be. In other cases, the process proceeds to step 82. As mentioned above, THW≧50°C and N≦400O
rpm and is on the higher load side than the solid line a in FIG. 4, the injection instruction flag is turned on. When the injection instruction flag is turned on, an injection instruction signal is output to the output port 0, so that the knock suppressant is supplied to the engine in a constant amount over time. Furthermore, when the injection instruction flag is turned on, the basic advance angle value θ is calculated as an optimal value according to the operating state of the engine by a well-known method that will not be described in this specification. pt K advance angle correction value Δθ is added, and the ignition timing is changed to △
The angle is advanced by θ. As a result, an increase in torque can be suppressed. It is preferable that the advance angle correction value Δθ is changed in accordance with the rotational speed EN, as shown by the solid line in FIG. This will be explained later (see Figure 7).
This is because the difference between the MBT (minimum advance value at which the maximum torque can be obtained) and the limit advance value for knocking to occur changes depending on the rotational relationship.

FIG. 6 shows how the torque obtained by advancing the ignition timing changes when the knock suppressant is supplied as described above. In the figure, C indicates the torque characteristics when no knock suppressant is added, and d indicates the torque characteristics when it is supplied [7].The shaded area indicates the range where knocking occurs. As shown in C, when no knock suppressant is supplied, non-king occurs on the retard side of MBT.

Since it is in the active range, it is not possible to set a large advance angle, and the torque obtained is therefore small. However, if a knock suppressant is supplied as shown in d, the knocking region will be reduced to MB.
The angle is advanced from T, so it is possible to increase the torque by advancing the angle at MBTt. The reason why the torque characteristic curves when the knock suppressant (d) is supplied and when the knock suppressant (C) is not supplied is different from each other is that the knock suppressant containing alcohol or the like generates a large amount of heat. This is based on the inside of the refrigerator, such as a drop in intake air temperature.

FIG. 7 is a diagram for explaining why the supply amount of the knock suppressant is made constant over time regardless of the rotational speed, that is, why the structure of the present invention is adopted. In the figure, e represents the torque characteristic at the limit of knocking when no knock suppressant is supplied, and f represents the torque characteristic due to MBT. That is, when the rotational speed is low, the difference between e and f is large, and at a higher rotational speed, the difference is small. Therefore, in the low rotational speed region, it is advantageous to have a large ratio of the knock suppressant supply amount to the fuel supply amount in order to obtain the torque characteristic f by MBT, and in the high rotational speed region, the above ratio should not be increased so much. It is possible to obtain the torque characteristic f even without this. Therefore, if the amount of knock suppressant supplied is constant regardless of the rotational speed, the ratio can be controlled as described above.

As described above, according to the present invention, the amount of knock suppressant supplied is controlled to the amount necessary to obtain the optimum torque at that time, so that efficient knock control using the knock suppressant can be performed. can.

It is clear that, in addition to the rotation speed and the throttle valve opening, the rotation range and the intake manifold negative pressure may be used as operating state parameters for determining the knocking occurrence region.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a block diagram of the control circuit of FIG. 1, and FIG. 3 is a partial flowchart of a processing program of a microcomputer in the control circuit.
Fig. 4 is a characteristic diagram of the knocking occurrence region, Fig. 5 is a characteristic diagram of advance angle correction value with respect to rotational speed, Fig. 6 is a characteristic diagram of torque with respect to fire advance angle, and Fig. 7 is a characteristic diagram of MBT and knocking occurrence with respect to rotational speed. It is a torque characteristic diagram by a limit. 10... Throttle valve, 12... Intake passage, 16...
...Injection valve, 18...Tank, 20...Pump, 22
... Pressure adjustment valve, 24 ... Control circuit, 28 ... Throttle sensor, 32 ... Water temperature sensor, 38 ... Crank angle sensor, 46 ... Ignition coil, 48 ... Spark plug, 50... A/D converter, 52... Speed signal forming circuit, 54... CP IJ, 60... Output boat, 64... Ignition control circuit, 66... Small fire device,
68...ROM, 70...RQ Patent Applicant: Toyota Motor Corporation Patent Application Agent: Akira Aoki, Patent Attorney, Kazuyuki Chikara, Patent Attorney: Akiyuki Yamaguchi Figure 4 Rotational Speed (rl)m) Figure 5 Rotational speed (rl) m) Figure 6 Ignition advance angle Figure 7 101000200030004000 (19 Rotational speed

Claims (1)

[Claims] 1. If the operating state parameters of the engine are detected and it is determined from the detected operating state parameters that the operating state of the engine is in a predetermined region in which non-king is considered to be cow, then A method for controlling knocking in an internal combustion engine, the method comprising supplying a certain amount of knock suppressant to the engine. 2. The knocking control method according to claim 1, wherein when the knock suppressant is supplied, the knock suppressant is continuously supplied from an electromagnetic injection valve provided in the intake system of the engine. 3. When the knock suppressant is supplied, the knock suppressant is
The knocking control method according to claim 1, wherein the knocking control method is intermittently supplied from an electromagnetic injection valve provided in an intake system of an engine. 4. The knocking control method according to claim 1, wherein the operating state parameters to be detected include engine rotational speed l and throttle valve opening. 57. The non-king control according to claim 4, wherein the predetermined region where the kinging is considered to occur is a region where the engine rotational speed is below the set rotational speed and the throttle valve opening is above the reference value υ. Method. 6. The knocking control method according to claim 5, wherein the reference value is changed according to the engine rotational speed l.