JPH051393B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention has an intake control valve that is closed when the amount of intake air is low to give a swirling flow to the intake air, and the ignition timing of an engine that controls the air-fuel ratio lean. Regarding control method.

[Background of the invention]

In an engine that imparts a swirling flow to the intake air-fuel mixture for the purpose of improving combustion efficiency when the amount of intake air is low, for example, the intake passage immediately upstream of the intake valve is divided into two, and one side is bypassed. is equipped with a swirl control valve as an intake control valve, and when the opening of the intake throttle valve is small (for example, 50 degrees or less), the swirl control valve is closed, and when it is 50 degrees or more, it is opened. As a result, when the valve is closed, a swirling flow is imparted to the intake air guided from inside the swirl passage to the combustion chamber.

For engines that have such an intake control valve and control the air-fuel ratio lean in the light load range,
Conventionally, when the swirl control valve is closed and the intake pipe negative pressure exceeds a set value (for example, 681 mmHg), the air-fuel ratio is switched from lean control to rich control in order to increase engine output, and the air-fuel ratio is gradually adjusted according to the intake pipe pressure. The ignition timing was controlled accordingly.

Further, when the intake pipe negative pressure exceeds a second set value (for example, 720 mmHg) which is larger than the above set value, the air-fuel ratio is further enriched and the ignition timing is determined accordingly. In this case, the ignition timing is determined by comparing a map showing the relationship between engine speed and intake pipe negative pressure with the actual engine speed and intake pipe negative pressure, and by interpolating the map data.

However, when swirl occurs, although the combustion condition improves, knocking becomes more likely to occur, and when the ignition timing exceeds the second set value, the calculated value obtained by interpolating the map data is too advanced with respect to the required value. As a result, knocking may occur, which hinders improvements in engine output.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine ignition timing control method that prevents knocking in a high engine load range where swirl occurs and improves engine output.

[Summary of the invention]

The first invention has an intake control valve that is closed when the amount of intake air is low to give a swirling flow to the intake air, controls the air-fuel ratio in a lean manner, and provides map data showing the relationship between engine speed and intake pipe negative force. In the case where the ignition timing is determined by interpolation calculation, if the intake pipe negative pressure is higher than the set value when the intake control valve is closed, the ignition timing is determined by subtracting a certain value from the value obtained by the interpolation calculation of the map data. It is characterized by this.

Further, the second invention has an intake control valve that is closed when the amount of intake air is low to give a swirling flow to the intake air, lean control of the air-fuel ratio, and map data showing the relationship between engine speed and intake pipe negative pressure. In the device in which the ignition timing is determined by interpolation calculation of This feature is characterized in that the ignition timing is set to a value corrected according to the difference from the above value.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a part of the engine according to the present invention, the range between line A-A and line B-B is a view of the engine seen from above, and the left side of line B-B shows a cross section of the cylinder block. . The fuel injection valve 1 is attached to a throttle body 5 via a support member 3. An intake pipe 4 connected to an air filter 2 is connected to the upstream side of the fuel injection valve 1, and an intake throttle valve 7 is connected to the downstream side of the body 5. It is provided.

Throttle body 5 is intake manifold 8
It is connected to the cylinder head 9 via. A suction passage 11 formed in the cylinder head 9 is divided into two by a partition wall 13, and a helical bypass 1 is provided.
5 and a swirl passage 17 are formed, and the helical bypass 15 is provided with a swirl control valve 21 supported pivotally on a shaft 19. Bypass valve 21 is connected to actuator 2 via link 23.
It is connected with 5. The shape of the swirl passage 17 is determined so that when the bypass valve 21 is closed, the intake air-fuel mixture is drawn into the combustion chamber 29 through the intake port 27 while forming a swirling flow. In addition, numeral 31 is an intake valve, 33 is an exhaust valve, 3
5 indicates an exhaust passage.

The actuator 25 includes a diaphragm 25a,
Chamber 25b partitioned by diaphragm 25a
and a rod 25 fixed to the diaphragm 25a.
c and a spring 25d that always urges the rod 25c inward to the actuator, and the rod c is connected to the link 23.

The chamber 25b of the actuator 25 is connected to the first port of the solenoid valve 39 through a passage 37, and the intake air upstream of the throttle body 5 is connected to the second port of the solenoid valve 39 through the passage 41. Intake negative pressure of the intake manifold 8 is guided to the port through a passage 43, and when it is energized, the first port and the second port are connected, and when it is demagnetized, the first port and the second port are connected. The third port is connected,
It is always demagnetized. A filter 45 and a check valve 47 are interposed in the passage 43.

The secondary side terminal of the igniter 49 is connected to a distributor 51, and the high voltage boosted by the igniter 49 is supplied to the spark plug 52 via the distributor 51. The distributor 51 is provided with a reference position sensor 53 that outputs a pulse signal S1 for every 30 degrees of crank angle, and a cylinder discrimination sensor 55 that outputs a pulse signal S2 for every 360 degrees of crank angle. The sensors 53 and 55 are each connected to a control circuit 57. The control terminal of the igniter 49 is also the control circuit 57
A high voltage is supplied to the distributor 51 in response to the ignition timing signal S3 from the distributor.

The intake pressure sensor 59 is connected to the control circuit 57 and supplies the control circuit 57 with an intake pipe pressure signal S4 corresponding to the pressure inside the intake manifold 8. The intake temperature sensor 61 is connected to the control circuit 57 and supplies the control circuit 57 with an intake temperature signal S5 corresponding to the intake temperature. The throttle valve opening position sensor 63 is connected to the control circuit 57
The throttle valve position signal S6 indicating the opening degree of the throttle valve 7 is supplied to the control circuit 57. Further, the electromagnetic three-way switching valve 39 is also connected to the control circuit 57, and is excited in response to the electromagnetic valve opening/closing command signal S7.
8. Furthermore, a water temperature sensor 65
is connected to the control circuit 57 and supplies a water temperature signal S9 corresponding to the temperature of the cooling water in the water jacket 67 to the control circuit 57.

As shown in FIG. 2, the control circuit 57 includes a central processing unit (CPU) 57a that controls various devices;
Read-on memory (ROM) 57b in which map data and programs indicating the relationship between engine speed NE and intake pipe negative pressure PM are written in advance, and random access memory (RAM) in which numerical values and flags of calculation processes are written in predetermined areas. 57c, A/D converter (ADC) 57d that converts analog input signals into digital signals, input/output interface (I/O) 57e to which various digital signals are input and output, auxiliary power supply when the engine is stopped. It is comprised of a backup memory (BU-RAM) 57f which is supplied with power from the BU-RAM to hold memory, and a bus line 57g to which each of these devices is connected. A program to be described later is written in advance in the ROM 57b.

Next, FIG. 3 shows the contents of the ignition timing calculation routine of the ignition timing control program executed by the control circuit 57. In the same figure, when the ignition timing calculation routine is started, the ROM is loaded in step 100.
The ignition timing θ is calculated by interpolating the map by comparing the map data showing the relationship between the engine speed NE and the intake pipe negative pressure PM stored in 57b with the actual engine speed NE' and the intake pipe negative pressure PM'. _M is required.

Next, in step 102, it is determined whether the swirl control valve 21 is open. This is done by determining whether the opening degree of the intake throttle valve 7 has reached 50 degrees or more based on the throttle valve position signal S6 output from the throttle valve position sensor 63. If it is determined in step 102 that the swirl control valve 21 is open, the process jumps to step 108,
At step 108, the program returns to the main routine.

On the other hand, if it is determined in step 102 that the swirl control valve 21 is closed, the process moves to step 104, where the intake pipe negative pressure is reduced.
PM is the set value of intake pipe negative pressure at the time when the set air heat ratio A/F suddenly changes from lean to rich.
A determination is made as to whether or not it is PM ₂ (for example, 720 mmHg) or higher. If the determination in step 104 is "NO", the process jumps to step 108 and returns to the main routine. If it is determined as "YES" in step 104, the process moves to step 106, and in step ₁₀₆ , the ignition timing θ (= θ _M -C) and returns to the main routine at step 108.

FIG. 5 shows the ignition timing control characteristics according to this embodiment. As shown in the figure, the ignition timing was conventionally selected as a point on the straight line P (dotted line) by interpolating between map points MP ₁ and MP ₂ ;
Between MP ₁ and MP ₂ , the required ignition timing (curve Q) shows a peculiar change because the A/F setting changes rapidly from the lean side to the rich side. As a result, in the past, the ignition timing θ _M obtained by interpolation calculation deviates significantly from the required ignition timing in the interval PM=PM ₂ to _{PM 3} , which may cause knocking and reduce engine output.

On the other hand, in this embodiment, a fixed value C is subtracted from the ignition timing θ _M obtained by interpolation calculation shown by a straight line P to perform retardation correction, and the intake pipe negative pressure PM, which causes the swirl control valve 21 to open, is By stopping the retardation correction when PM= _PM3 , the ignition timing can be controlled in a state close to the required ignition timing.

Next, FIG. 4 shows the contents of another embodiment of the ignition timing calculation routine. In the figure, when the ignition timing calculation routine is started, it is determined in step 200 whether or not the swirl control valve 21 is open. If it is determined in step 200 that the swirl control valve 21 is open, the process moves to step 202, and in step 202, the relationship between the engine speed and the intake pipe negative pressure is determined as in step 100 in FIG. The ignition timing θ _M is determined by interpolation calculation of the map shown in FIG.

On the other hand, if it is determined in step 200 that the swirl control valve 21 is closed, in step 204 the intake pipe negative pressure P is set to PPM ₁ (here, the set value PM ₁ is selected to be, for example, 681 mmHg). A determination is made as to whether or not there is one. If it is determined as "YES" in step 204, the process moves to step 206, and in step 206 it is determined whether PMPM ₂ (PM ₂ > PM ₁ , and the set value PM ₂ is selected to be, for example, 720 mmHg). It is determined whether If the determination in step 206 is "YES", the process moves to step 208, where the retard angle correction amount K(PM) is calculated using the following equation.

K(PM)=k(PM- _PM2 )...(1) In the above equation (1), k is a constant. Furthermore, in step 210, the ignition timing θ is calculated using the following equation.

θ=θ _M −k(PM) (2) As a result, the ignition timing θ is corrected to be retarded in proportion to the amount of increase in the intake pipe negative pressure PM. After calculating the ignition timing in step 210, the process returns to the main routine in step 212.

Further, if the determination in steps 204 and 206 is "NO", the process moves to step 202, and the processing described above is performed. FIG. 6 shows the ignition timing control characteristics according to this embodiment. As is clear from the figure, in this embodiment, when the swirl control valve 21 is open (PM
= PM ₃ ) (in the above example, the fuel amount is increased when PM = PM ₃ ), but according to this example, an ignition timing characteristic R close to the required ignition timing characteristic Q can be obtained. .

〔Effect of the invention〕

According to the present invention, it is possible to prevent knocking in a high engine load range where swirl occurs, thereby improving engine output and drivability.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of an engine to which the present invention is applied, Fig. 2 is a block diagram showing the structure of its control circuit, and Fig. 3 shows the contents of an ignition timing control routine executed by the control circuit. Flowchart: FIG. 4 is a flowchart showing the contents of another embodiment of the ignition timing control routine; FIG. 5 is a diagram showing ignition timing control characteristics according to an embodiment of the present invention; FIG.
The figure is a diagram showing ignition timing control characteristics according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Injection valve, 7... Intake throttle valve, 8... Intake manifold, 9... Cylinder head, 11... Intake passage, 13... Partition wall, 15... Bypass, 17... Swirl passage, 21... Swirl control valve,
49...igniter, 51...distributor,
52... Spark plug, 53, 55... Crank angle sensor, 57... Control circuit, 59... Intake pressure sensor, 6
3... Throttle valve position sensor.

Claims (1)

[Claims] 1. It has an intake control valve that is closed when the amount of intake air is low to give a swirling flow to the intake air, controls the air-fuel ratio leanly, and shows the relationship between engine speed and intake pipe negative pressure. In a device that determines the ignition timing by interpolation calculation of map data, if the intake pipe negative pressure is higher than the set value when the intake control valve is closed, the ignition timing is determined by subtracting a certain value from the value obtained by interpolation calculation of the map data. A method for controlling ignition timing of an engine, characterized in that: 2. The engine ignition timing control method according to claim 1, wherein the set value of the intake pipe negative pressure is the intake pipe negative pressure at a time when the set air-fuel ratio suddenly changes from lean to rich. . 3 It has an intake control valve that is closed when the amount of intake air is low to give a swirling flow to the intake air, controls the air-fuel ratio lean, and performs ignition by interpolating map data showing the relationship between engine speed and intake pipe negative pressure. In the device that determines the timing, if the intake pipe negative pressure is above the set value when the intake control valve is closed, the value obtained by interpolation calculation of the map data is used as the difference between the intake pipe negative pressure at that time and the set value. An ignition timing control method for an engine, characterized in that the ignition timing is set to a value corrected accordingly. 4. Engine ignition timing control according to claim 3, wherein the set value of the intake pipe negative pressure is the intake pipe negative pressure at a time when the set air-fuel ratio suddenly changes from rich to lean. Method.