JPS6176760A - Method of controlling ignition timing of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the fuel consumption and drivability of an engine from deteriorating, by compensating the spark advance of the engine with the use of a compensated spark retard value for retarding the timing of ignition and a compensated spark advance for advancing the timing of ignition. CONSTITUTION:When an ignition switch is turned on, at step 100 initialization is made, and then at step 101 the content of a RAM is cleared and initial data are set thereon. At step 102 the amount Q of intake-air, the rotational speed N of an engine and the amount Q/N of intake-air per one rotation of the engine are calculated. At steps 103 and 104 a spark advance Sig is calculated and a fuel injection time T is calculated. Further, at step 103 the spark advance is compensated with the use of a compensated spark retard value for retarding the ignition timing and a compensated spark advance value for advancing the ignition timing. Thus, it is possible to prevent the consumption and drivability of the engine from deteriorating.

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 more particularly to a method for controlling the ignition timing of an internal combustion engine equipped with a catalyst for purifying exhaust gas.

[Conventional technology]

In conventional internal combustion engines installed in vehicles, the basic ignition advance is calculated based on the engine load (intake pipe pressure, which means the amount of intake air per revolution of the engine) and engine speed, and the basic ignition advance is calculated based on the engine speed and the intake air temperature and engine cooling. An ignition timing control method is used in which the basic ignition advance angle is corrected according to the water temperature, etc. to determine the ignition advance angle, and the igniter is controlled so that the ignition 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 carbon dioxide 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. However, when the engine is restarted after being left in a stopped state, the exhaust gas purification rate deteriorates because the catalyst temperature is low. Therefore, it is necessary to quickly raise the catalyst temperature at the time of engine cooling start, and one method for raising the catalyst temperature is to retard the ignition timing (Japanese Patent Laid-Open No. 72257/1983). That is, when the ignition timing is retarded, the thermal efficiency of the engine decreases and the energy in the exhaust gas increases.In addition, since the engine output decreases, the amount by which the driver depresses the accelerator pedal increases, resulting in an increase in catalyst temperature.

- When the engine cooling water temperature is low, the combustion state of the engine is poor and the air-fuel ratio is too rich, making it difficult to produce -1π output, so the driver tends to operate the throttle valve to the open side and adjust the ignition timing. Even without controlling to the retarded side, the catalyst temperature tends to rise slightly. However, when the engine cooling water temperature is extremely low, it is necessary to advance the ignition timing to prevent an excessive drop in output.

Conventionally, in order to raise the temperature of the catalyst and prevent an excessive drop in output at extremely low temperatures, the ignition timing was controlled in the following manner in response to changes in engine cooling water temperature.

That is, when the engine cooling water temperature is extremely low, the ignition timing is advanced in order to prevent an excessive drop in the output, but the advance value is not increased too much in consideration of the catalyst temperature.

When the temperature is low, the advance angle value is decreased to control the ignition timing to the retarded side as the problem of excessive output decrease decreases, and the catalyst temperature is increased. When the engine cooling water temperature is high, that is, when the engine is warmed up, the catalyst temperature is also high, so the retard amount is reduced so that ignition is performed at the basic ignition advance angle.

[Problem that the invention seeks to solve]

However, in conventional ignition timing control methods, the ignition timing is retarded in response to changes in engine cooling water temperature. However, because the rate of increase in the catalyst temperature and the rate of increase in the engine cooling water temperature are different, even if the catalyst temperature rises to the activation temperature or higher after a predetermined period of time has passed after the low temperature start, the engine cooling water temperature is still at a low temperature. There is a problem in that the ignition timing is unnecessarily retarded in response to the engine cooling water temperature, resulting in poor fuel efficiency and drivability.

[Next method to solve the problem]

The present invention solves the above problem by separately setting an advance value for preventing an excessive drop in output and a retard value for warming up the catalyst. The corrected retard value is determined to retard the ignition timing according to the engine temperature and is gradually attenuated from the time of engine start, and the engine temperature is set to retard the ignition timing according to the engine temperature.
The ignition advance angle determined by the engine load and engine speed is corrected using a correction advance value determined to advance the ignition timing according to the The ignition timing is controlled based on the

[Effect]

According to the present invention, when the engine is started, the corrected retard value changes depending on the engine cooling water temperature at the time of engine start, but after being determined at the time of engine start, the corrected retard value is gradually attenuated at a predetermined period, so that the catalyst temperature is adjusted to the activation ratio. It becomes zero when it becomes visible.

Then, the ignition advance angle is corrected by the corrected advance value and the corrected retard value changed as described above, and the ignition timing is controlled. By gradually attenuating the corrected retard value from the time of startup in this way, the ignition timing is retarded for the period necessary to raise the catalyst temperature, and the same is true when starting at an extremely low temperature or at room temperature. The catalyst temperature is increased.

〔effect〕

As explained above, according to the present invention, since the ignition timing is not unnecessarily retarded by retarding the ignition timing for the period necessary to raise the catalyst temperature, deterioration of fuel efficiency and drivability is prevented. The effect is that it can be done.

〔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 explained 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). Air flow meter 2Fi, rotatably installed in the damping chamber
It consists of a measuring brake (L7j) 2A and a potentiometer 2B that detects the opening degree of the two measuring plates. Therefore, the amount of intake air is detected from the voltage output from the potentiometer 2B.

A throttle valve 6 is arranged downstream of the air flow meter 2, and a surge tank 8 is arranged downstream of the throttle valve 6.
is provided. 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 the combustion chamber 14A of the engine body 14, and is connected to the combustion chamber 14A of the engine body 14.
It is connected via a 4AJ-It 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 cooling water temperature sensor, IViO, sensor that detects the engine cooling water temperature.

A companion ignition plaque 20 attached to the engine body 14 is connected to a distributor 26, and the distributor 26 is connected to an igniter 28. The distributor 26 is provided with a cylinder discrimination sensor 30 and an engine rotation angle sensor 32, each of which includes a pickup fixed to the distributor housing and a signal rotor fixed to the distributor shaft. This cylinder discrimination sensor 30 outputs a cylinder discrimination signal to an electronic control circuit 34 composed of a microcomputer or the like every 720 degrees of 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 crank angle, for example. A position signal is output to the electronic control circuit 34.

As shown in FIG. 3, the electronic control circuit 34 includes random access memory +RAM) 36, read-only memory +7 (R
OM) 38, microprocessing unit (MPU)
)40. Input/output boat 46, input port 48, output port
) 50, 52 and a path 54 connecting these, and the MPU 40 has a clock tcLOcK)4.
2 and timer 44 are connected. Input/output boat 4
6, an air flow meter 2 and an engine coolant temperature sensor 2 are connected to each other via buffers 55, 56, a multiplexer 58, and an analog/digital converter (A/D converter) 60.
4 is connected. The input boat 48 has a buffer 6
2 and 0.2 through comparator 64. In addition to the sensor 1 being connected, a cylinder discrimination sensor 30 and a rotation angle sensor 32 are also connected via a waveform shaping circuit 66 . The output boat 50 is connected to the igniter 28 via a drive circuit 68, and is connected to the fuel injection valve 12 via a drive circuit 70. The above-mentioned ROMIC has a pre-memory of control programs and the like which will be explained below.

FIG. 4 shows the main routine of the control program. When the ignition switch is turned on, the input/output board etc. are initialized in step 100, and the input/output ports etc. are initialized in step 101.
Clear the contents of RAM and set the initial data. For example, in step 101, flag F8TA is set. In the next step 102, the air flow meter output, rotation angle sensor output, etc. are taken in, and the intake air f
Calculate kQ, engine rotation speed N1, and intake air tQ/N per engine rotation. In steps 103 and 104, the ignition advance angle Sig is calculated based on the data calculated as described above, and the fuel injection time T is also calculated. Then, the ignition advance angle S calculated as above
The igniter and the fuel injection valve are controlled by an interrupt routine (not shown) so that ignition and fuel injection are performed at ignition time and fuel injection time T.

FIG. 5 shows an interrupt routine every 4 m5ec. In step 160, the count value CT is incremented by 1, and in steps 161 and 162, the count value cT is limited so that it does not exceed 30υO (〆λsec).

FIG. 1 shows details of the ignition advance angle calculation routine in the first embodiment of the present invention, that is, step 103 in FIG. In other words, it is determined whether or not the engine has been successfully started. If the flag FIITA is set, the flag FaT is reset in step 166, and then a corrected retard value 5COLD2 for raising the catalyst temperature is calculated in steps 167 to 171. That is, in step 167, it is determined whether the engine cooling water temperature is 30°C or lower, and if the water temperature is 30°C or lower, the correction retard value 5COLD2 is set to 10'CA in step 169, and if the water temperature is over 30°C, step At step 168, it is determined whether the cooling water temperature is less than 70°C. If the cooling water temperature is 70℃ or higher, step 1
71, the correction retard value S'COL D2 is set to 0'CA,
If the cooling water temperature is 70° C. or lower, a corrected retard value 5COLD2 is calculated according to the following formula.

・・・・・・(1) As a friend, THW is the current engine coolant temperature.

As a result of the above, the corrected retard value 5COLD2 changes as shown in FIG. 6 according to the engine coolant temperature.

In step 172, the basic ignition advance angle is set to 5B based on the engine rotation speed N and the intake air amount Q/N per engine rotation.
SE is calculated, and the correction retard value 5COLD2 is adjusted to 1°C at a cycle of 3 seconds in steps 173 to 177.
Attenuate by A and reach 0°CA. That is, step 1
In step 73, it is determined whether or not the count value cT is less than 750. If the count value CT is 750 or more, in step 174, the corrected retard value 5COLD2 is decreased by 0.1° CA, and in step 175, the corrected retard value 5COLD2 is set to 0. If it is less than 0, the correction retard value 5COL is determined in step 177.
Set D2 to O'CA, and if it is -10 or more, step 17
6, the count VLCT is set to O.

In the next steps 178 to 182, a correction lead angle value 5COLD1t- is set to prevent an excessive drop in output at extremely low temperatures.
calculate. That is, in step 178, it is determined whether or not the engine cooling water temperature exceeds 110°C.
If it is below 0℃, the correction advance angle value 5COLDI is set in step 182.
is set to 10° CA, and if the water temperature exceeds 110°C, it is determined in step 179 whether the engine cooling water temperature is less than 10°C. If the water temperature is 10°C or higher, the correction advance value 5COLDI is set to 0°CA in step 180, and the water temperature is 10°C.
If it is less than 5COLDI, a corrected advance angle value 5COLDI is calculated according to the following formula.

As a result of the above, the corrected advance angle value 5COLDI changes as shown in FIG. 6 according to the engine coolant temperature.

Then, in step 183, the basic ignition advance angle is set to 5BSE.
The ignition advance angle Sig is calculated by adding the K corrected advance angle values 5COI and Dl and subtracting the corrected retardation value 5COLD2.

Next, a second embodiment of the present invention will be described. In this embodiment, the corrected retard value 5COLD2 is attenuated every predetermined number of ignitions from the time of starting. FIG. 7 shows the calculation routine for the ignition advance angle. This routine differs from the routine in Figure 1.
0' It is executed by an interrupt every time the ignition of each cylinder occurs, but the same parts as in FIG. 1 are given the same reference numerals and the explanation is omitted. In step 103 of the main routine shown in FIG. 4, the basic ignition advance angle is calculated.

When 90' CABTDC of each cylinder is determined (based on the cylinder discrimination signal and crank angle reference position signal), the routine of FIG. 7 is executed, and in steps 167 to 171 the corrected retard value is 5COLD2 is calculated,
In step 190, CRev is incremented by 1. In the next step 191, it is determined whether the count value CR*v is 200 (66 rotations) or more, and if the count value 0 Raw is 200 or more, step 192
Steps 174 and 17 set the count value CRav to 0.
The corrected retard value 5COLD2 is attenuated at 5°177.

In this embodiment, the corrected retard value is attenuated every predetermined number of ignitions, so when the engine speed is high and the amount of exhaust gas is large, the attenuation of the corrected retard value becomes faster, and drivability and fuel efficiency can be further improved. can.

FIG. 8 shows a comparison between the ignition advance angle correction amount 5COLD fscOI, Di-8COLD2) when controlled as described above and the conventional ignition advance angle correction 1sPA.

Figure 8 shows the results when the engine is started when the engine cooling water temperature is -20°C (condition 1), when the engine is started when the engine cooling water temperature is 20°C (condition 2), and when the engine is started when the engine cooling water temperature is 40°C (condition 3). ), which shows the change in engine cooling water temperature over time.

Moreover, FIG. 80 shows the change in the correction amount under condition 1, L5,
Figure 8 (0 indicates the change in correction amount under condition 2, Figure 8 0
shows the change in the amount of correction under condition 3. As can be understood from the figure, under conditions 2 and 3, there is not much difference between the correction amount 5COLD of this embodiment and the conventional correction amount SPA, but in the case of condition 1, the conventional correction amount is on the retard side. Because it is large, the angle is over-delayed.

Next, a third embodiment of the present invention will be described. In this embodiment, the cycle for attenuating the correction retard angle is changed depending on the engine cooling water temperature at the time of starting. That is, when the engine cooling water temperature is low, the corrected retard value required at the time of starting is large, and since emissions are originally large, the attenuation speed of the corrected retard value is increased.

In this case, since the corrected retard value is large, the ignition timing is retarded for a relatively long time even if the attenuation speed is increased. When the engine coolant temperature is moderate, the corrected retard value required at startup becomes smaller, so even when the coolant temperature is low, the damping speed is slowed down and the ignition timing is retarded for the same amount of time as when the coolant temperature is low. to be done.

When the engine coolant temperature is high, for example when restarting after warming up, the catalyst temperature is relatively high and there is almost no need to retard the ignition timing, so the engine will be more damped than when the coolant temperature is low. Increase speed.

A routine for attenuating the corrected retard value of this embodiment will be explained with reference to FIG. Note that the calculation routines for the corrected advance value 5COLDI and the ignition advance angle are the same as those in the first embodiment, so their explanation will be omitted. Detailed explanation.

In step 195, it is determined whether the engine cooling water temperature at the time of engine startup is 0°C or higher. If the cooling water temperature is less than 0°C, the count value Ti500 is set in step 197, and the process then proceeds to step 169, where the cooling water temperature is 0°C. In the above case, the count value T is set to 750 in step 196, and after t, step 1
Proceed to 67.

Further, in step 198 it is determined whether the cooling water temperature is below 50°C, and if it is over 50°C, the count value T is set to 250 in step 199.

As a result of the above, the count value T changes as shown in FIG. 10 according to the engine coolant temperature THW, and the corrected retard value 5
COLD2f'i Changes as shown in FIG. 6 as in the first embodiment.

In step 200, it is determined whether the count value CT, which is incremented every 4 m5ec, is greater than or equal to the count value T set as described above, and if it is greater than or equal to T, step 174 is performed.
-Attenuate in step 177 in the same manner as in the first embodiment.

As a result of the above, when THW<0°C, the corrected retard value is attenuated every ';l sec, when 0°C≦THW≦50°C, the corrected retard value is attenuated every 3 sec, and when THW>
When the temperature is 50° C., the correction retard value is attenuated every l sec.

As explained above, according to this embodiment, since the attenuation speed of the correction retard value is changed according to the engine cooling water temperature at the time of starting, the ignition timing is The period of extra retardation is shortened, further improving fuel efficiency and drivability.

A comparison of the correction amount 5COLD of the first embodiment and the correction amount A of the third embodiment under the same conditions (condition 1, condition 2, condition 3) as in the case of FIG. 8 is shown. As understood from the figure,
Under condition 2, the correction amount of the first embodiment and the correction amount of the third embodiment are the same, but under conditions 1 and 3, the retardation time of the third embodiment is longer than that of the first embodiment. It's shorter.

Next, a fourth embodiment of the present invention will be described. In this embodiment, 'i' for attenuating the corrected retard value is changed according to the current engine cooling water temperature. In other words, when the engine coolant @ is low, the corrected retard value required at startup is large, so the damping value is increased to quickly bring the corrected retard value to 0, and when the coolant temperature is medium, the corrected retard value is small. Therefore, set the damping value to less than a pebble and adjust the correction retard value to a gentle KO.
When the cooling water temperature is high, the catalyst itself is relatively high, so the damping value is made larger than the damping value when the cooling water temperature is low, and the corrected retard value is brought to 0 more quickly.

FIG. 12 shows the corrected retard value 5COLD2 in this embodiment.
Here is an elaborate routine to attenuate the .

In addition, when starting, the corrected retard value 5COLD2 and the corrected lead angle value 5
The routine for determining COLD1 and the like are the same as those in the first embodiment, so their explanation will be omitted. After calculating the corrected retard value at the time of starting, in step 200, the count ([CT is 3000 (12
sec ) or more, and if the count value CT is 30
If it is 00 or more, the engine cooling water temperature is set to 0 in step 201.
It is determined whether the cooling water temperature is less than 50°C or not, and at step 202 it is also determined whether the cooling water temperature is 50°C or less. If the cooling water temperature is less than 0°C, the damping value S i is set to 0.3°CA in step 205, and if the cooling water temperature is 0°C or higher and 50°C or lower, the damping value S is set to 0.2°CA in step 204. If the cooling water temperature exceeds 50°C, the attenuation value S is set in step 203.
is 0.4°CA. Then, in step 206, the correction retard value is attenuated by subtracting the attenuation value S determined according to the cooling water temperature as described above from the corrected retard value 5COLD2, and in steps 207 and 209, the corrected retard value is in step 208.
Set the count value cT to 0.

The correction values in this embodiment change in substantially the same manner as in FIG. 11.

Although the above explanation has been made using specific numerical values to simplify the explanation, the present invention is not limited to these numerical values, and the optimum numerical value can be selected for each engine. Although an example has been described using the engine cooling water temperature as the engine temperature, the engine cooling water temperature may be used, or the damping period may be determined by the number of fuel injections. Further, the present invention can be applied to an engine in which the basic ignition advance angle and basic fuel injection time are determined depending on the intake pipe pressure and the engine speed.

[Brief explanation of drawings]

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 showing an example of an engine equipped with an ignition timing control device to which the present invention is applied, and FIG. Fig. 2 is a block diagram showing details of the control circuit, Fig. 4 is a flow chart showing the main routine of the embodiment of the present invention, and Fig. 5 is a flow chart showing the interrupt routine every 4 m5ec of the embodiment of the present invention. 6 is a diagram showing nine corrected advance angle values and corrected retard values determined according to the engine cooling water temperature in the embodiment of the present invention, and FIG. 7 is a diagram showing the ignition advance angle value in the second embodiment of the present invention. Flowchart showing the calculation routine, Figure 8 (B). 0.0) is a diagram for explaining changes in the correction amount in the first and second embodiments, and FIG. 9 is a flowchart showing a routine for changing the attenuation period in the third embodiment of the present invention. 1st
FIG. 0 is a diagram showing the change in the count value T of the third embodiment, FIG. 11 is a diagram illustrating the change in the correction amount of the third embodiment, and FIG. FIG. 4 is a flowchart showing a damping routine in the fourth embodiment. FIG. 24... Engine cooling water temperature, 28... Igniter, 34... Control circuit. Figure 5 Figure 6 Figure 10 THW'C

Claims (1)

[Claims] (1) When controlling the ignition timing of an internal combustion engine equipped with a catalyst that purifies exhaust gas based on the ignition advance determined by the engine load and engine speed, the engine temperature is lower than a predetermined temperature. A correction retard value that is determined to retard the ignition timing according to the temperature and is gradually attenuated from the time the engine starts, and a correction retard value that is determined to retard the ignition timing according to the engine temperature, and a correction retard value that is determined to retard the ignition timing according to the engine temperature, and a correction retard value that is determined to retard the ignition timing according to the engine temperature. An ignition timing control method for an internal combustion engine, characterized in that the ignition advance angle is corrected using a correction advance value determined to advance timing.