JPS6172876A - Ignition timing controlling method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve an exhaust gas emission control rate in time of steady driving, by controlling the ignition timing of an internal-combustion engine provided with a catalyzer, controlling an emission of exhaust gas, for timing advance on the basis of engine load and speed, when a steady driving state is continues, controlling the ignition timing with a delayed timing advance. CONSTITUTION:In time of engine running, a control circuit 34 first calculates a suction air quantity per engine rotation on the basis of each output signal out of an air flow meter 2 and a turning angle sensor 32, and according to the calculation result, it calculates ignition timing advance and fuel injection time. And, according to the calculated timing advance and fuel injection time, an ignitor 28 and a fuel injection valve 12 both are controlled. At the above- mentioned, the ignition timing advance is one as being found after properly compensating a fundamental ignition timing advance calculated from the engine speed and the suction air quantity per engine rotation, and when a car steady running state is continues to be more than the specified time (for example, 60sec), the ignition timing is made so as to be controlled with a more delayed timing advance than the said ignition timing advance.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling the ignition timing of an internal combustion engine, and particularly to a method for controlling the ignition timing of an internal combustion engine equipped with a catalyst for purifying exhaust gas and mounted on a vehicle. Regarding the method.

[Conventional technology]

In conventional internal combustion engines installed in vehicles, the basic ignition advance is calculated based on the engine load (intake pipe pressure or intake air amount per engine revolution) and engine speed, and is adjusted based on intake air temperature, engine cooling water temperature, etc. An ignition timing control method is used in which the basic ignition advance angle is corrected accordingly to determine the ignition advance angle, and the igniter is controlled so that the igniter is ignited at this ignition advance angle. In addition, in order to purify exhaust gas, such internal combustion engines use an oxidation catalyst that oxidizes carbon monoxide and hydrocarbons in the exhaust gas to purify them into harmless carbon dioxide and water vapor. A catalytic converter is installed, which is filled with a three-way catalyst that simultaneously oxidizes nitrogen and reduces nitrogen oxides to harmless carbon dioxide, water vapor, and nitrogen. In order to improve the purification rate of this catalytic converter, it is necessary to maintain the temperature of the catalyst above the temperature at which the catalyst is activated, and if the catalyst temperature falls below the temperature at which the catalyst is activated, the purification rate of exhaust gas will decrease. Getting worse.

Conventionally, there is no technology to raise the catalyst temperature to a point where it activates when the catalyst temperature drops.Therefore, there is no technology to raise the temperature to the point where the catalyst activates when the catalyst temperature drops.Therefore, there is no technology to increase the fuel injection amount during high loads to lower the catalyst temperature and prevent the catalytic converter from overheating, or to emit nitrogen oxides. There are six technologies (Japanese Unexamined Patent Publication No. 158370/1983) that reduce the amount of nitrogen oxides emitted by delaying the ignition timing according to the engine cooling water temperature in the medium-rotation and medium-load range where the amount of nitrogen oxides is relatively large.

[Problem that the invention seeks to solve]

Incidentally, from the viewpoint of improving fuel efficiency, lightweight internal combustion engines with low friction loss have recently been developed.

When a catalytic converter is attached to such a fuel-efficient internal combustion engine to purify exhaust gas, the amount of fuel supplied is small due to the low fuel consumption, which inevitably reduces the amount of exhaust gas emitted, and the temperature of the exhaust gas also increases. There may be cases where the catalyst temperature falls below the temperature at which the catalyst is activated due to insufficient energy from the exhaust gas necessary to raise the temperature of the catalyst. In other words, when the vehicle is driving normally, deceleration and acceleration are repeated, so a sufficient amount of exhaust gas is supplied to the catalytic converter during acceleration to compensate for the lack of energy due to exhaust gas during deceleration. be able to. However, when the vehicle continues to run in a steady state, there is no situation where the load becomes high and generates a large amount of exhaust gas like when accelerating under normal running conditions, and the load etc. hardly change. , the load becomes lighter on average than under normal driving conditions, and the exhaust gas becomes insufficient in energy, causing the catalyst temperature to drop. Then, when the catalyst temperature decreases in this way, it becomes below the temperature at which the catalyst is activated, causing a problem that the exhaust gas purification rate decreases.

[Means for solving problems]

In order to solve the above problems, the present invention provides an ignition advance angle based on the engine load and engine speed when controlling the ignition timing of an internal combustion engine equipped with a catalyst for purifying exhaust gas and mounted on a vehicle. The present invention is characterized in that the ignition timing is controlled, and the ignition timing is controlled at an ignition advance angle that is retarded than the ignition advance angle when the steady running state of the vehicle continues.

[Effect]

According to the present invention, when the steady running state of the vehicle continues, the ignition timing is controlled using an ignition advance angle that is retarded than the ignition advance angle based on the engine load and engine speed. As a result, the amount of unburned components in the exhaust gas increases and the unburned components are re-burned within the catalytic converter, thereby raising the catalyst temperature.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent the catalyst temperature from falling below the activation temperature when the steady running state continues, thereby improving the exhaust gas purification rate during steady running. Effects can be obtained.

〔Example〕

Next, an example of an internal combustion engine equipped with an ignition timing control device to which the present invention is applied will be described in detail with reference to FIG. This engine is controlled by an electronic control circuit such as a microcomputer, and as shown in the figure, is equipped with an air flow meter 2 as an intake air amount sensor downstream of an air cleaner (not shown). The air flow meter 2 consists of two meji-killing plates rotatably provided in the damping chamber and the meji-killing plate 2.
It is composed of a potentiometer 2B that detects the opening degree of the person. Therefore, the amount of intake air is determined by potentiometer 2B.
It is detected from the voltage output from the Further, an intake air temperature sensor 4 is provided near the air flow meter 2 to detect the temperature of intake air.

A throttle valve 6 is disposed downstream of the air flow meter 2, a throttle sensor 22 for detecting vehicle acceleration is attached to the throttle valve 6, and a surge tank 8 is disposed downstream of the throttle valve 6. ing. An intake manifold 10 is connected to the surge tank 8, and a fuel injection valve 12 is disposed protruding into the intake manifold 10. The intake manifold 10 is connected to a combustion chamber 14A of the engine body 14, and the combustion chamber 14A of the engine is connected via an exhaust manifold 16 to a catalytic converter (not shown) filled with a three-way catalyst. Note that 20 is a spark plug, and 24 is a coolant temperature sensor that detects the engine coolant temperature.

A spark plug 20 attached to the engine body 14 is connected to a distributor 26, and the distributor 26 is connected to an igniter 28. This distributor 26 was composed of a pickup fixed to the distributor housing and a signal rotor fixed to the distributor shaft. A cylinder discrimination sensor 30 and an engine rotation angle sensor 32 are provided. This cylinder discrimination sensor 30 outputs a cylinder discrimination signal to an electronic control circuit 34 made up of a microcomputer or the like every 720 degrees of the crank angle, for example, and the engine rotation angle sensor 32 outputs a cylinder discrimination signal based on the crank angle every 30 degrees of the crank angle. A position signal is output to the electronic control circuit 34. In addition, 18 is a vehicle speed sensor composed of a magnet rotated by a speedometer cable, and a reed switch and a magnetically sensitive element arranged to face the magnet.

As shown in FIG. 3, the throttle sensor 22 includes an abbreviated rotating piece 80 whose base end is connected to the rotating shaft 6a of the throttle valve 6. The proximal end of the rotating piece 80 extends toward the distal end of the rotating piece 80, and one end of the first contact 82 is fixed so as not to come into contact with the distal end of the rotating piece 80. Furthermore, one end of a second contact 86 is fixed to the tip of the rotating piece 80 via an insulating material 84 so as to be parallel to the first contact 82 . This second contact 8
6 is grounded. A comb-shaped first electrode 88 and a comb-shaped second electrode 88
An electrode 90 is arranged to face the first contact 82 with the teeth of the other electrode interposed between the teeth of the other electrode. One ends of the first electrode 88 and the second electrode 90 are connected to a power source via a resistor 92 and a resistor 94, respectively, and are also connected to the electronic control circuit 34, respectively.

This throttle sensor is connected to the direction in which the throttle valve 6 opens (
When the rotating piece 80 is rotated in the direction of the arrow in the figure), the rotating piece 80 rotates and the first contact 82 and the second contact 86 are rotated.
Since the tip of the first contactor 82 alternately contacts the first electrode 88 and the second electrode 90 and is grounded while the electrodes are in contact with each other,
A pulse signal having a waveform as shown in FIG. 4 is output. Note that when the throttle valve is rotated in the closing direction, the first contact 82 and the second contact 86 are rotated in a non-contact state, so that no pulse signal is output.

As shown in FIG. 5, the electronic control circuit 34 includes a random access memory (RAM) 36, a read-only memory (ROM) 38, a central processing unit (CPU) 40, a clock (CLOCK) 41, and an input/output board. 42, an input port 44, a first output port 46, and a second output port 48, FLAM 36, ROM 38,
CPU 40, CLOCK 41, input/output boat 42, input boat 44, first output boat 46, and second output boat 48)'! , , are connected by a bus 50 such as a data bus or a control bus.

The input/output boat 42 is connected to an air flow meter 2 and a cooling water temperature sensor 2 via a buffer (not shown), a multiplexer 54, and an analog-to-digital (A/D) converter 56.
4, an intake air temperature sensor 4, etc. are connected thereto. The multiplexer 54 and A/D converter 56 are controlled by a control signal output from the input/output port 42. The input/output boat 44 includes a first electrode 8 of the throttle sensor 22.
8 and a second electrode 90 are connected, the cylinder discrimination sensor 30 and the engine rotation angle sensor 32 are connected via the waveform shaping circuit 64, and the vehicle speed sensor 18 is also connected via the waveform shaping circuit 60.

Further, the first output boat 46 is connected to the igniter 28 via a drive circuit 70, and the second output boat 48 is connected to the fuel injection valve 12 via a drive circuit 72. A control program described below is stored in advance in the ROM.

FIG. 6 shows the main routine of the control program. When the ignition switch is turned on, the input/output ports, etc. are initialized in step 100, and the input/output ports are initialized in step 101.
Clear the contents of RAM and set the initial data. In the next step 100, the air flow meter output, the rotation angle sensor output, etc. are taken in, and the intake air amount Q1, the engine rotation speed N, the intake air amount Q/N per engine rotation, etc. are calculated. In step 103 and step 104, the ignition advance angle S is calculated based on the various data calculated as described above.
ig and the fuel injection time T. Then, the igniter and fuel injection valve are controlled by an interrupt routine (not shown) so that ignition and fuel injection are performed at the ignition advance angle 8ig and the fuel injection time T calculated as described above.

FIG. 1 shows the details of the routine for calculating the ignition advance angle in the first embodiment of the present invention, that is, step 103 in FIG. FIG. 7 shows an interrupt routine every 4m5ec, in which the count value CT is incremented by 1 in step 110, and the count value CT is limited to not exceed 3,800 in steps 111 and 112.

The routine in Figure 1 is based on the basic ignition advance angle of 8B8Fi with the engine speed N and the intake air amount Q/N per engine revolution.
Calculate the basic ignition advance angle 8BSP and correct the ignition advance angle S.
This is executed after calculating ig, step 120
It is determined whether the count value CT is 3,750 (15 seconds) or more. If the count value CT is 3,750 or more, the count value C is set to 0 in step 121, the count value Cup is incremented by 1 in step 122, and the current intake air amount per engine revolution Q/N is determined in step 123. Let be Q/N i. Next step 124
Now, the amount of intake air per revolution of the engine Q/Ni
and the previous intake air per engine revolution itQ/Ni-
The difference in feed value from 1 is 0.1! /rev, or less, it is determined whether the running state of the vehicle is a steady running state. If it is not in a steady running state, step 125
In step 126, the count value CT is set to 0, and in step 126, the count value cup is set to 0, and the process returns to step 123. If the vehicle is in a steady running state, it is determined in step 127 whether the count value cup is 4 (corresponding to 60 seconds) or more. . When the count value Cup is 4 or more, that is, when the steady running state continues for 60 seconds or more, step 128
In step 129, the count value Cup is set to 4 and the flag FRET is set. On the other hand, the count value Cup
is less than 4, the flag F RIT is reset in step 130.

In step 131, it is determined whether the flag FRIilT is set, and if it is set, the ignition advance angle Sig is decreased by 20'C'A in step 132, and the process proceeds to the next step, and the flag PRET is reset. If so, proceed to the next step. As a result of the above, the steady running state of the vehicle lasts for a predetermined period of time (60 sec in the above example).
), the ignition timing is controlled at an ignition advance angle that is retarded by a predetermined angle (200CA in the above example) than usual.

Next, the ignition advance angle calculation routine in the second embodiment of the present invention will be explained with reference to FIG. In this example, the sixth
At step 102 in the figure, a vehicle speed 8PD is calculated in advance based on the vehicle speed sensor output.

First, in step 140, the main ignition advance angle is set to 8 based on the intake air amount Q/N per engine revolution and the engine speed N.
B8E is calculated, and the count value CT incremented in the routine of FIG. 7 in step 141 is 3.75.
Determine whether it is greater than or equal to 0.

If the count value CT is 3,750 or more, step 1
After incrementing the count value Cup by 1 in step 42 and setting the count value CT to 0 in step 143, the process proceeds to step 14.
4, the current intake air amount per engine rotation Q/N, vehicle speed SPD, and engine rotation speed N are respectively Q/Nl, 8
PDi, Ni.

In steps 145 to 147, the supply value of the difference between the current intake air amount per engine revolution Q/Ni and the previous intake air amount per engine revolution Q/N'+-t is determined to be 0.11. / rev or less, current vehicle speed 8P
The fuel supply value of the difference between Dl and the previous vehicle speed 8 P Di-1 is 5
km/h or less, or the fuel supply value of the difference between the current engine speed Ni and the previous engine speed N1-1 is 20O
By determining whether the rpm is below or below, it is determined whether the vehicle is in a steady running state. If the vehicle is not running steadily, the count value Cu is set to O in step 148, and the process returns to step 143; if the vehicle is running steadily, it is determined in step 149 whether the count value Cup is 4 or more. . When the count value Cup is less than 4, in step 150, the basic ignition advance angle 5BSR is set as the ignition advance angle Sig,
When the count value Cup is 4 or more, the count value Cup is set to 4 in step 151, and the value obtained by subtracting 20'CA from the basic ignition advance angle 5BSFf is set as the ignition advance angle 8 in step 152.
It is assumed to be 1g. Then, in step 153, the ignition advance angle Sig
It is determined whether or not the ignition advance angle is equal to or higher than the compression top dead center (TDC), and if the ignition advance angle is less than the compression top dead center, the value of the top dead center is set as the ignition advance angle Sig in step 154. In the above embodiment, it is preferable to correct the ignition advance angle Sig based on the intake air temperature and the engine cooling water temperature.

Next, a third embodiment of the present invention will be described. In this embodiment, the ignition advance retardation control is canceled when the vehicle is accelerated while the steady running state continues for a predetermined period of time. First, a routine for determining acceleration will be explained with reference to FIG.

FIG. 9 shows an interrupt routine that is interrupted at the falling edge of the signal (FIG. 4) output from the first and second electrodes of the throttle sensor. First, step 160
Then, it is determined whether the interrupt is caused by a signal output from the first electrode or not. In the case of an interruption due to a signal from the first electrode, it is determined in step 164 whether the 7-lag F18C has been reset, and if the flag F'tsc has been reset, the flag F18C is set in step 165. On the other hand, flag p
If tsc is set, the count value t, which is incremented by 1 in the interrupt routine every 4 m5ec, is set to 0 in step 169. Conversely, step 16
When it is determined that the interrupt is caused by the signal of the second electrode at 0,
In step 162, it is determined whether the flag F18C is set. If it is set, the flag ptsc is reset in step 163, and if it is reset, the count value t is set to O in step 169. Next step 1
At step 66, it is determined whether or not the count value t is less than 50 (200 msec). If the count value t is less than 50, the count value t is set to 0 at step 167, and at step 16
At 8, set the acceleration flag FACCt.

As a result of the above, when the time interval between the fall of the signal output from the first electrode and the fall of the signal output from the second electrode is less than 200 m5ec, it is determined that acceleration is occurring, and the acceleration flag FAcc is set. be done.

FIG. 10 shows the ignition advance calculation routine of this embodiment. In FIG. 10, the step of determining the steady running state is omitted, and the main illustration is the retardation during steady running and the cancellation of this retardation. . In step 171, the steady running state of the vehicle is determined by determining whether the count value Cup is 4 or more.
Determine whether the process has continued for c or more. Count value Cu
If p is less than 4, the basic ignition advance angle is set to 8B in step 172.
SB is the ignition advance angle Sig, and when the count value Cu is 4 or more, the count value Cup is set to 4 in step 173, and then it is determined in step 174 whether the acceleration flag FACC has been reset. If the acceleration flag FACC has been reset, step 178 is performed as in the second embodiment.
So the basic ignition advance angle is 5B8F! The value obtained by subtracting 20' CA from the ignition advance angle Sig is set as the ignition advance angle Sig.
It is determined whether or not g is advanced from compression top dead center. If the ignition advance angle Sig is retarded from the compression top dead center, the compression top dead center is set as the ignition advance angle Sig in step 179. On the other hand, if the acceleration flag FACC is set, the acceleration flag FACC is reset in step 175, the count value Cup is reset in step 176, and the basic ignition advance angle 8B8E is changed to the ignition advance angle S1g in step 177.
To cancel the ignition advance retardation. In this embodiment as well, it is preferable to correct the ignition advance angle and SIg based on the engine cooling water temperature and the like.

Note that although the above description has been made using specific numerical values to simplify the explanation, the present invention is not limited to these numerical values, and the optimum value is selected for each type of engine.

In addition, although the above description describes an engine that determines the basic ignition advance angle based on the amount of intake air per revolution and the engine speed, the present invention is applicable to an engine that determines the basic ignition advance angle based on the intake pipe pressure and the engine speed. It is also possible to apply. Furthermore, the steady running state may be determined from a change in vehicle speed or a change in engine speed.゛

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the ignition advance calculation routine of the first embodiment of the present invention, FIG. 2 is a schematic diagram of an engine equipped with an ignition timing control device to which the present invention is applied, and FIG. A detailed diagram of the sensor, FIG. 4 is a diagram showing the output signal of the throttle sensor, FIG. 5 is a block diagram showing details of the control circuit of FIG. 2, and FIG. 6 is a main routine in an embodiment of the present invention. Flowcharts, FIG. 7 is a flowchart showing the interrupt routine for every 4m5e, FIG. 8 is a flowchart showing the ignition advance calculation routine in the second embodiment of the present invention, and FIG. 9 is a flowchart showing the ignition advance calculation routine in the third embodiment of the present invention. A flowchart showing the determination routine, and FIG. 10 is a flowchart showing the ignition advance angle calculation routine of the third embodiment. 2... Air flow meter, 26... Distributor, 28... Igniter, 32 ...
Rotation angle sensor, 34... control circuit.

Claims (1)

[Claims] (1) When controlling the ignition timing of an internal combustion engine equipped with a catalyst that purifies exhaust gas and mounted on a vehicle, the ignition timing is controlled by an ignition advance angle based on the engine load and engine speed. 1. An ignition timing control method for an internal combustion engine, comprising controlling ignition timing with an ignition advance angle that is retarded than the ignition advance angle when a steady running state continues.