JPH0278747A - engine control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine control device, and particularly to an engine control device suitable for an engine control device using an electronic throttle.

[Prior art] Conventionally, the amount of fuel supplied is controlled by operating the throttle valve with an accelerator pedal connected to the throttle valve by a wire, and measuring the amount of air sucked into the cylinder by some method. The main type of control was so-called intake air priority control, which determined the amount of fuel to be supplied based on the amount of intake air.

However, the problem with intake air priority control is that there is a difference in response characteristics between air and fuel, i.e. air has a relatively light mass and is therefore highly responsive, whereas fuel has a heavy mass and therefore has a poor response. It had become.

For example, when the throttle opens during acceleration, the amount of intake air increases quickly with the opening of the throttle valve, but relatively heavy fuel cannot reach the cylinder immediately even if the amount of fuel supplied is large. - Temporary over-air conditions occur.

In view of this problem, the amount of fuel is supplied in proportion to the amount of accelerator pedal as described in Japanese Patent Application Laid-open No. 10792/1983. An engine control device that does not prioritize and control intake air has been proposed.

[Problem to be solved by the invention]

However, in the conventional technology described above, since the fuel supply amount is directly determined from the accelerator operation amount, the fuel supply device such as an injector and the device such as a throttle actuator that controls the air amount determined based on the accelerator operation amount are extremely accurate. If it did not operate properly, the fuel and air supply would be too high or too low. Therefore, it has been confirmed that the air-fuel ratio deviates significantly from the target air-fuel ratio due to this, resulting in deterioration of exhaust characteristics.

Furthermore, it has been known that the above-mentioned problem is largely related to aging of fuel supply devices such as injectors and variations in product manufacturing.

[Means to solve the problem]

In order to determine the above object, the engine control device includes an accelerator operation amount detection means for detecting the accelerator operation amount, an engine rotation speed detection means for detecting the engine rotation speed, and an exhaust state detection means for detecting the exhaust state. A basic fuel supply amount determining means for determining a basic fuel supply amount based on an accelerator operation amount and an engine rotational speed; and a correction amount determining means for determining a correction amount for correcting the basic fuel supply amount based on an exhaust state.

A memory update means that repeatedly writes a learned value based on the correction amount to a memory means that is not erased even after engine operation is stopped, and determines the fuel supply amount based on the basic fuel supply amount, the correction value, and the learned value. The fuel supply amount determining means is configured to determine the fuel supply amount, and the fuel supply means is configured based on the fuel supply amount.

[Effect]

According to the above configuration, the basic fuel supply amount is determined from the accelerator operation amount and the engine rotation speed, the correction value is determined based on the exhaust condition, the learned value is written in the storage means based on the correction value, and the basic fuel supply amount is The fuel supply amount is determined based on the correction value and the learned value.

Therefore, the air-fuel ratio can be maintained at a desired air-fuel ratio, and good exhaust characteristics can be obtained.

〔Example〕

Embodiments of the present invention will be explained below.

A fuel injection system embodying the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, air enters an air cleaner 1 through an inlet 2, and a takt 3. It passes through a throttle body 5 having a throttle valve 4 driven by a throttle actuator 18 for controlling the amount of intake air and enters a collector 8 . Here the air is distributed to each intake pipe 6 leading to the internal combustion engine 7 and drawn into the cylinders. On the other hand, fuel is sucked from the fuel tank 9 by a fuel pump 10 and pressurized by a fuel damper 11. Fuel filter 12. Injection valve 13. It is supplied to a fuel system to which a fuel pressure regulator 14 is connected. The fuel is regulated to a constant level by the regulator 14 and injected into the intake pipe 8 from an injection valve 13 provided in the intake pipe 8. The rotation of the crankshaft is detected by a crank angle sensor 15 and input to a control unit 18 . Also, the accelerator operation is performed using the accelerator sensor 16. It is detected by the accelerator switch 17 and input to the control unit 18. The opening degree of the throttle valve is detected by a throttle angle sensor 19 and input to the control unit 18 .

FIG. 2 shows details of the control unit. The control unit 18 is an MPU.

It is composed of ROM, RAM, Ilo, various sensors that detect the operating state of the engine and input it to the control unit, and an actuator for operating the engine state. The accelerator sensor 16° throttle angle sensor 19
The output signal is input to the MPU through Ilo, and the ROM
It is processed according to a program written in advance.

Its contents are stored in RAM at appropriate times. The processing result is Ilo
The signal is output as a signal to activate an actuator such as an injector.

In the above configuration, the operation of the control unit will be specifically explained based on the flowchart of FIG. 3.

FIG. 3 is a flowchart for determining the injection pulse width Tt. In step 300, accelerator operation amount 0&C, engine cooling water temperature Two, engine rotation speed N, intake air temperature T
^, the battery voltage Vs is taken in. Step 301
The number of applied pulses n from the accelerator operation θ & C taken in
p is found. The number of applied pulses np is the accelerator operation amount θ
, C, 1, for example, as shown in FIG. 4, is stored in the ROM in advance, and the number of applied pulses corresponding to the accelerator operation amount θ&C is read out. In step 302, the basic injection amount Tp is determined from the engine speed N and the number of applied pulses np. The basic injection amount Tp is uniquely determined from the engine rotation axis N and the applied pulse part np, and for example, the characteristics shown in FIG. This is done by being read out. In step 303, a learning correction coefficient KL is determined based on the number of rotations N and the number of applied pulses np. The learning correction coefficient KL is uniquely determined from the rotation speed N and the number of applied pulses np. The learning correction is performed to maintain the air-fuel ratio at a target value against system variations and secular changes, and the learning correction coefficient is updated and stored one by one. Note that details of the learning correction coefficient will be described later. The learning correction coefficient is determined for the rotation speed N and the number of applied pulses np, and for example, as shown in FIG.
The engine speed N and the number of applied pulses np are stored in AM.
The value corresponding to is read out. In step 304, a determination is made as to whether or not the operation is steady. If it is determined that the operation is steady, the process proceeds to step 305. If it is determined that the operation is not steady, the injection correction amount ΔTp is set to zero in step 306 and the process proceeds to step 307. In step 305, the rotation change amount per predetermined time Δt is determined. Injection correction amount ΔT from ΔN
0 for which P is calculated, for example, rotational change amount Δ per predetermined time
Characteristics as shown in FIG. 8 uniquely determined for N/Δt are stored in the ROM in advance, and the injection correction amount ΔTp corresponding to the rotational change amount ΔN per predetermined time Δt at that time is read out. It is carried out by Generally, if ΔN/Δt is positive, the correction amount ΔTp is considered negative;
It is assumed that ΔTp decreases as Δt increases.

That is, when the rotational fluctuation is positive and large, the fuel injection amount is decreased accordingly, and the torque is decreased. Also, ΔN/
If Δt is negative, the correction amount ΔTP is taken as positive, and ΔTP increases as ΔN/Δt decreases. That is, when the rotational fluctuation is negative and large, the fuel injection amount is increased accordingly and the torque is increased. Figure 8 (b
) shows the variation in the rotational speed N and the injection amount correction amount corresponding to the variation. In FIG. 8, the dotted line portion represents rotational fluctuations due to the conventional engine system. In this application, ΔTp is corrected according to rotational fluctuations. As a result, rotational fluctuations are suppressed as shown by the solid curved line of the rotational speed N in FIG. In step 307, a water temperature increase correction coefficient KT^ is determined from the engine cooling water temperature Tw.

The water temperature increase correction coefficient KT^ is uniquely determined from the engine cooling water temperature.
This is done by storing the temperature in the engine and reading it out in accordance with the engine cooling water temperature. At step 308, an air temperature correction coefficient Kt^ is determined from the intake air temperature T^. The air temperature correction coefficient KT^ is uniquely determined according to the intake air temperature T^, and for example, the characteristics shown in Fig. 11 are stored in advance in a ROM and read out according to the intake air temperature T^. It is done. In step 309, a battery voltage correction amount Ta is determined based on the battery voltage Va. The battery voltage correction amount TB is uniquely determined according to the battery voltage VB, and is performed by, for example, storing the characteristics shown in FIG. 10 in advance in a ROM and reading them out according to the battery voltage. In step 310, the accelerator operation amount θ&C,
Engine coolant temperature Tw + engine speed change ΔN/
The injection pulse width T1 is determined by correcting Δ in accordance with the intake air temperature TA and the battery voltage VB. Injection pulse @T
.

is determined, for example, by the following equation (L).

Tt= (1+KTW+KTA)* ((X+KL)*
Tp + ΔT p + T a ・
(1) Here, α is an air-fuel ratio correction coefficient calculated based on the Ox sensor signal described below.

Here, the injection pulse width is determined by the overlap of addition and multiplication.
), but the form of calculation in equation 1 is not restricted to addition 9 multiplication, and can be obtained using other equations as well.

Based on the original injection pulse width Ts, fuel is injected from the injector in the relationship shown in FIG. 16, for example. Further, based on the number of applied pulses np, the throttle valve is opened according to the relationship shown in FIG. 6, for example.

The updating of the learning correction coefficient described above will be explained based on the flowcharts of FIGS. 12 and 13.

FIG. 12 is a flowchart showing the conditions for writing the learning correction coefficient KL. In step 1201, it is determined whether the 02 sensor is activated. If it is determined that the OX sensor is activated, the process moves to step 1202. If the 02 sensor is not activated, appropriate learning control cannot be performed, so step 121
2, the air-fuel ratio correction coefficient α is set to 1.0, that is, the air-fuel ratio is not corrected based on feedback control. In step 1202, it is determined whether the engine coolant temperature Tw has reached a predetermined value.

In the step, the water temperature Tw is set at 80°C.
If it is determined that has reached the predetermined value, step 12
Move to 03. If the engine cooling water temperature has not reached 80°C, it is determined that the engine is not warmed up enough and is not suitable for feedback control, and the process proceeds to step 1212, where the air-fuel ratio correction coefficient α is set to 1.0. In step 1203, it is determined whether a predetermined accelerator time or more has elapsed.

If it is determined that the accelerator predetermined time has elapsed, the process proceeds to step 1205; if the accelerator predetermined time has not elapsed, it is assumed that the engine condition is still transient, and feedback control is not performed, and the process proceeds to step 1212.

In step 1205, the engine speed and the number of applied pulses np are determined.
A learning area is required. The learning area is divided into two-dimensional areas, for example, as shown in FIG. 7, depending on the determination width between the predetermined width of the rotational speed N and the applied pulse width np. Each area is stored in each area of the backup RAM. Step 12
In step 06, it is determined whether the previous learning area is the same as the current learning area. If they are the same, a flag is set in the learning Δ in step 1207, and if they are not the same area, the flag is set in the learning Δ. The learning flag is determined, for example, depending on whether 1 or O is stored in the RAM area corresponding to the learning flag.

FIG. 13 is a flowchart showing updating of the learning correction coefficient.

In step 13o3, it is determined whether the 02 sensor output voltage is larger than the slice level SL. 02
If it is determined that the sensor output voltage is larger than the slice level SL, the air-fuel ratio is determined to be greater than a certain value, that is, rich, and the process proceeds to step 1304. and,
After step 1304, the air-fuel ratio correction coefficient α is operated to decrease the air-fuel ratio so as to decrease the air-fuel ratio. In step 1304, it is determined whether the previous 02 sensor output voltage was greater than the slice level SL. If the previous output voltage of the 02 sensor was smaller than the slice level SL, it means that the lean state has been reversed to the rich state. At this time, the previous air-fuel ratio correction number α is used to calculate the proportional adjustment that takes into account the response delay of the fuel injection control based on the output of the Oz sensor.
The value subtracted from is set as a new air-fuel ratio correction coefficient α.

If it is determined in step 1304 that the previous OR sensor output voltage is smaller than the slice level SL, the rich state continues. In step 1308, continuing from the previous time, an integral P that is sufficiently smaller than the proportional base ■ is subtracted from the air-fuel ratio correction coefficient α so as to further reduce the air-fuel ratio. In step 1303, the Oz sensor output voltage reaches slice level SL.
If it is determined that the air-fuel ratio is smaller than the predetermined value, it is determined that the air-fuel ratio is smaller than the predetermined value, that is, the lean state is reached, and the air-fuel ratio is thereafter operated to increase. If it is determined that the vehicle is in a lean state, the process proceeds to step 1305, where it is further determined whether the previous output voltage of the 02 sensor was higher than the slice level. Last time was slice level SL
If it is smaller than , then the condition is still lean, and the air-fuel ratio is operated to increase, and the value obtained by adding the integral I to the previous air-fuel ratio correction coefficient α is set as the new air-fuel ratio correction coefficient α.
shall be. If it is determined in step 1305 that the previous O2 sensor output voltage was greater than the slice level SL, it has changed from rich to lean, so the value of the proportional table P that takes into account the response delay of the control system is set to the previous air-fuel ratio correction coefficient α. The added value is set as a new air-fuel ratio correction coefficient α. Figure 14 (
a) Changes in the 02 sensor output voltage to -1 are shown in relation to the slice level SL. Figure 14(a)-
2 shows the change in the air-fuel ratio correction coefficient α in response to the above-mentioned operation. In step 1310, it is determined whether a flag is set for learning Δ. If the flag is set for learning Δ, the process advances to step 1311 and the following operations are performed. Step 131
If the learning Δ is 0 and the flag is not set, this flowchart ends. In step 1311, it is determined whether or not the 02 sensor signal has been repeatedly inverted between rich and lean three times. The reason why 3 times is written here is simply because this number is generally widely used;
It can also be used for other times, such as times or seven times. If it is determined in step 1311 that the reversal has not been repeated three times, the counter is incremented by one when the 02 sensor signal changes from rich to lean.

If it is determined in step 1311 that the 02 sensor has been reversed from rich to lean three times, step 13
Proceed to step 12. In step 1311, reversal from rich to lean is considered, but reversal from lean to rich or bidirectional reversal between rich and lean may also be considered. In step 1312, it is determined whether the peak value of α has been sampled a predetermined number of times. When the predetermined number of samplings have been completed, a learning completion flag is set in step 1314. If it is determined in step 1312 that the peak value of α has not been sampled a predetermined number of times, it is determined in step 1315 whether α is the peak value, and if it is the peak value, sampling is performed. Although sampling is performed here when the air-fuel ratio correction coefficient α is at its peak, this is one form of determining the conditions for sampling, and sampling may be performed when other conditions other than the peak value are reached. In step 1316, it is determined whether the learning completion flag is set. If the learning completion flag is set, subsequent processing is performed. If the learning flag has not been set, the flowchart ends in order to continue operations such as sampling. In step 1317, the total sum of the sampled air-fuel ratio correction coefficients α is obtained, divided by the number of sampling times, and the sampled air-fuel ratio correction coefficients are averaged. Averaging can also be weighted based on sampling conditions. In step 1318, 1.0 is subtracted from the average air-fuel ratio correction coefficient i to obtain the deviation δ.

In step 1318, the learning correction amount Xn is determined based on the deviation δ. The learning correction amount Xn is determined by, for example, dividing the deviation δ into regions, storing the corresponding learning correction amount Xn in the ROM in advance as shown in FIG. 14(b), and reading out the deviation δ. Note that FIG. 14(a)-2 shows the average air-fuel ratio correction coefficient 7. The concept of deviation δ is illustrated.

In step 1320, the learning correction amount Xn is added to the previous learning correction coefficient and determined. However, the content of the learning correction amount xn can be not only positive but also negative. .

In step 1321, the learning completion flag is cleared and the process moves to the first learning.

Next, control during idling will be explained using the flowchart of FIG. 15.

In step 15o2, first, it is determined whether the engine speed N has reached the cranking speed Nst. If the engine rotational speed N has not reached the cranking rotational speed N s t in step 1502, it means that complete combustion has not occurred, and the process proceeds to step 1504.

In step 1504, the number of applied pulses nPst at the time of starting is determined from the engine coolant temperature Tw and output to the throttle actuator. The number of applied pulses nPst is, for example, ROM
Characteristics as shown in FIG. 17 are stored in , and can be obtained by reading out the number of applied pulses corresponding to the characteristics. If the engine speed has reached the cranking speed Nst in step 1502, the process advances to step 1503.

In step 1503, a determination is made as to whether or not it is in an idle state. Whether or not the vehicle is in an idle state is determined based on, for example, the output of a throttle sensor. If it is not in the idle state, the process advances to step 1506, where the number of applied pulses np is determined from the accelerator operation amount θ&C, and the difference (n-n) from the current number of pulses is calculated.
If p) is positive, a signal is output to the slot and actuator so that it moves in the opening direction, and if it is negative, it moves in the closing direction. If it is in the idle state in step 1503, step 1
Proceed to 505 and set the target rotation speed N5 from the engine cooling water temperature Tw.
et and the reference pulse number n Pset are determined. In steps 1507 and 1508, the vehicle speed Sp is changed to the correction value SP.
1 or less, or whether the engine speed N is less than or equal to a predetermined value N1. If No, the process proceeds to step 1510, where it is determined whether the neutral switch is ON or not, and based on that determination, the applied pulse is maintained. Ru. Step 15
If the vehicle speed Sp is less than the predetermined value Spi in step 07 and step 1508, and the engine speed N is less than the predetermined value Ns in step 1509, the process proceeds to step 1509, where it is determined whether the neutral switch is ON. When the 221 tral switch is ON, the process proceeds to step 1511, where feedback control is performed on the engine speed so that the engine speed N becomes NM@tl. If the neutral switch is not ON, the process proceeds to step 1512, where engine speed feedback control is performed so that the engine speed N becomes Ngetz.

Next, correction of the number of output pulses and abnormality display will be explained using the flowchart shown in FIG.

If the engine speed is greater than or equal to the cranking speed PJgt in step 1501, and it is determined in step 1503 that the engine is not in an idling state, the process proceeds to step 2109. In step 2109, the throttle opening degrees θ and h are detected. The throttle opening degree is obtained by taking in the output of the throttle sensor 9.

In step 2102, the throttle opening θtho corresponding to the actual throttle opening θth and the current output pulse number n is determined.
is calculated, and the difference Δθth is calculated. Step 2103
Then, it is determined whether Δθ is within a predetermined value ε, and if it exceeds a predetermined value E, an indicator lamp for indicating an abnormality is turned on in step 2104. In step 2105, the output pulse number n is corrected from the throttle opening θtho based on the actual throttle opening (+th) and the output pulse number, or in step 2106, the applied pulse number nP is determined from the accelerator operation amount θ, , and the current correction Pulses are output to the throttle actuator to correct the difference (n - np) between the number of pulses and the number of pulses n.However, when the abnormality display indicator is ON, the output pulses are limited to the limit pulse amount n determined by the accelerator operation amount θ. If it exceeds the limit pulse nL, the output is made to become the limit pulse nL.

For example, the limiting pulse has characteristics as shown in Fig. 22 in the ROM.
You can obtain it by storing it in your memory and reading it out.

Another embodiment for output pulse correction and abnormality display will be described using the flowchart shown in FIG.

If it is determined in step 1501 that the engine rotational speed is greater than the cranking rotational speed N s and that it is not in the idle state in step 1503, it is determined in step 2201 whether the idle switch has just changed from ON to OFF or from OFF to ON. It will be done. If it is not immediately after the change, the process advances to step 2206.

If the idle switch has just changed, the process proceeds to step 2202, and the throttle opening θthsε immediately after the idle switch has changed.
The difference Δθ between and Δθth corresponding to the current number of output pulses n
I ask for something. In step 2203, 800 is compared with a predetermined value ε. If Δθth is within the predetermined value ε, the process proceeds to step 2205, but if Δθth exceeds the correction value, an indicator lamp for abnormality is turned on in step 2204, and then the process proceeds to step 2205. In step 2205, the current output pulse n is corrected based on the throttle opening degree θthsε immediately after the idle switch is changed based on the throttle opening degree θth based on the number n of output pulses. In step 2206, a pulse is output to the throttle actuator based on the correction.

〔Effect of the invention〕

As described above, according to the present invention, the basic fuel supply amount is determined,
A correction value is calculated based on the exhaust condition, a learned value is written based on the correction value into a storage means that will not be erased even after engine operation is stopped, and the fuel supply amount is determined based on the basic fuel supply amount, the correction value, and the learned value. It is possible to obtain a desired air-fuel ratio even if there are changes over time such as variations in production, etc., and good exhaust characteristics can be obtained.

[Brief explanation of the drawing]

Figure 1 is a system diagram, Figure 2 is a detailed diagram of the control unit, Figure 3 is a flowchart for determining the injection pulse width Ti, Figure 4 is a diagram showing the relationship between the accelerator operation amount and the number of applied pulses, and Figure 5. is a basic injection map, Figure 6 is a diagram showing the relationship between the number of applied pulses and throttle valve opening, Figure 7 is a learning correction map, Figure 8 is a diagram showing the injection correction amount, and Figure 9 is a diagram showing the relationship between the number of applied pulses and the throttle valve opening. Diagram showing the relationship between water temperature increase correction coefficients, 1st
Figure 0 shows the relationship between battery voltage and battery voltage correction, Figure 11 shows the relationship between intake air temperature and air temperature correction coefficient, and Figures 12 and 13 show the flow for writing the learning correction coefficient. Figure 14 is a diagram for explaining learning correction, Figure 15 is a flowchart at idle,
Figure 16 is a diagram showing the relationship between injection pulse width and injection amount, Figure 17 is a diagram showing the relationship between engine cooling water temperature and the number of applied pulses at startup, and Figure 18 is a diagram showing the relationship between engine cooling water temperature and the reference number of pulses. Figure 19 is a diagram showing the relationship between engine cooling water temperature and target rotation speed, Figures 20 and 21 are flowcharts for correcting the number of output pulses, and Figure 22 is the relationship between accelerator operation amount and limit pulse. FIG. 5... Throttle actuator, 9... Throttle sensor, 13... Injector, 15... Crank angle sensor, 16... Accelerator sensor, 17... Accelerator tea 2 mouth 3rd Kyo 40th 5th (2) Engine rotation control N (rPWL) 6th mouth 70th tea 8th time Yuhe r-1 hecha 110 V skin man 13 ('''C) #12 Figure 130 fytsEJ Nijishin A Washia 11' Hhfw(t)
Engine Me Tube Unii TIA/(Hinocha Figure 22)

Claims (1)

[Scope of Claims] 1. An accelerator operation amount detection means for detecting an accelerator operation amount; an engine rotation speed detection means for detecting an engine rotation speed; an exhaust state detection means for detecting an exhaust state; a basic fuel supply amount determining means for determining a basic fuel supply amount based on the engine speed; a correction amount determining means for determining a correction amount for correcting the basic fuel supply amount based on the exhaust condition; a memory update means for repeatedly writing a learned value based on the above into a memory means which is not erased even after the engine operation is stopped; and a fuel supply amount determining means for determining the fuel supply amount based on the basic fuel supply amount, the correction value and the learned value. An engine control device comprising: a means for supplying fuel based on the amount of fuel supplied. 2. An accelerator operation amount detection means for detecting an accelerator operation amount, an engine rotation speed detection means for detecting an engine rotation speed, and an exhaust state detection means for detecting an exhaust condition, based on the accelerator operation amount and the engine rotation speed. basic fuel supply amount determining means for determining a basic fuel supply amount based on the exhaust condition; correction amount determining means for determining a correction amount for correcting the basic fuel supply amount based on the exhaust condition; , memory updating means that repeatedly writes data into a storage means that is not erased even after engine operation is stopped, which is divided into values based on engine speed and accelerator operation amount, and learning values based on engine rotation speed and accelerator operation amount. reading means for reading out the fuel supply amount; fuel supply amount determining means for determining the fuel supply amount based on the basic fuel supply amount, the correction value, and the read learning value; An engine control device comprising: fuel supply means for supplying fuel. 3. In claim 2, an engine rotational speed change amount determining means for determining the amount of change in the engine rotational speed per predetermined time; and a second correction amount based on the amount of change in the engine rotational speed per predetermined time. and a second correction amount determining means for determining the amount of fuel supplied, the fuel supply amount determining means is characterized in that the fuel supply amount is determined based on the basic fuel supply amount, the correction amount, the read learning value, and the second correction amount. Engine control device.