JPH0362892B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention sets a set value representing an engine load for each predetermined range of engine speed of an internal combustion engine,
The present invention relates to a fuel supply control method during high-load operation of an internal combustion engine, which enriches the air-fuel mixture supplied to the engine when the actual engine load is determined to be higher than the set value.

(Technical background of the invention and its problems) In general, in a fuel engine equipped with a fuel injection device, the opening time of the fuel injection valve is set based on the absolute pressure in the intake pipe of the engine and the engine speed.
The reference value Ti read out from the Ti map according to these detected values is set by multiplying it by various correction coefficients according to the driving state. When the engine is under high load operation, the reference value Ti is multiplied by the enrichment coefficient K _WOT , or the basic Ti
A WOT map for high-load operation, which is different from the WOT map, is provided separately, and the opening time of the fuel injection valve during high-load operation is read from the WOT map.
In order to obtain the required engine output, the air-fuel ratio of the air-fuel mixture supplied to the engine is set to a substantially constant value (for example, 12.0) on the richer side than the stoichiometric air-fuel ratio (14.7) throughout the entire high-load operating range. (For example, Japanese Patent Application Laid-open No. 137633/1983).

By the way, a vehicle equipped with an automatic transmission (hereinafter referred to as an A/T vehicle) is equipped with a torque converter as a power transmission device, and the power transmission efficiency of the torque converter, that is, the difference between the pump impeller and turbine impeller. Due to the power transmission characteristics of the engine, there is a region called stall rotation where the power transmission efficiency is poor up to a certain rotation range, but beyond that rotation range the power transmission efficiency suddenly becomes better. Therefore, in the case of an A/T vehicle, when the throttle pedal is depressed, the engine operates as if torque is being transmitted near the stall rotation, and during that time, the power transmission efficiency is poor, resulting in power loss. Therefore, when the engine speed is at idle and the accelerator pedal is pressed to start from a stopped state by pressing the brake pedal, the negative pressure in the intake pipe increases once before the engine speed increases, and then the engine speed increases. tends to follow and rise. In other words, since the driver himself/herself understands the characteristics of the vehicle that it is sufficient to depress the accelerator pedal until it reaches stall rotation, when the driver depresses the accelerator pedal to stall rotation, the negative pressure in the intake pipe increases relatively quickly. Easy to do.

In most A/T vehicles, the driver's intention is to open the throttle valve to a range where the torque converter's power transmission efficiency is improved, so the negative pressure in the intake pipe normally reduces the air-fuel mixture supplied to the engine at high loads. There is a technology that executes enrichment when a predetermined value is reached for high load determination.

In the case of this technology, when cruising with a low engine load (for example, vehicle speed of about 40 km/h), if you slightly press the accelerator pedal to accelerate slightly, the WOT map usage zone ( (high-load operation range), and when you press the accelerator pedal like this.
If you temporarily enter the WOT map use zone and exit the WOT map use zone when you release the accelerator pedal, a torque shock will occur.

In order to eliminate such torque shock, when the negative pressure in the intake pipe temporarily enters the WOT map usage zone by slightly depressing the accelerator pedal during low-load driving as described above, the air-fuel mixture is enriched. It is conceivable to provide a delay timer to prevent this.

However, if a delay timer is simply installed considering only the torque shock problem when accelerating from low-load driving, the negative pressure in the intake pipe will increase when accelerating from a start.
Even when the vehicle quickly enters the WOT map usage zone, the delay timer is activated and the mixture is not immediately enriched until the time set by the delay timer has elapsed, resulting in a problem of poor acceleration performance.

(Object of the Invention) The present invention has been made in view of the above circumstances, and can prevent the occurrence of torque shock during acceleration from low-load driving, improve fuel economy, and improve acceleration performance when starting. An object of the present invention is to provide a method for controlling fuel supply during high-load operation of an internal combustion engine.

(Means for Solving the Problem) In order to solve the above-mentioned problem, in the present invention, a set value representing the engine load is set for each predetermined range of engine speed of the internal combustion engine, and the actual engine load is In a fuel supply control method during high load operation of an internal combustion engine, the fuel mixture supplied to the engine is enriched when the load is determined to be higher than a set value. When a rotation discrimination value is set and the vehicle speed is equal to or higher than a predetermined value, it is determined that the engine rotation speed is smaller than the low rotation discrimination value and the actual engine load is higher than the set value. , delaying execution of the enrichment of the air-fuel mixture for a predetermined period of time, and determining that when the vehicle speed is below a predetermined value, the engine speed is lower than the low rotation determination value and the actual engine load is higher than the set value; When it is determined that there is a load, the enrichment of the air-fuel mixture is immediately executed without delaying the predetermined time.

(Function) Even if the negative pressure in the intake pipe temporarily enters the WOT map use zone during acceleration from low-load driving, the mixture is not enriched, which suppresses the occurrence of torque shock and saves fuel consumption. improvement will be achieved. Furthermore, when starting (at low vehicle speed), acceleration performance is improved by enriching the air-fuel mixture as soon as the negative pressure in the intake pipe enters the WOT map use zone.

(Example) Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall configuration of a fuel supply control device to which the control method of the present invention is applied. An engine 1 is, for example, a four-cylinder internal combustion engine, and a midway of an intake pipe 2 connected to the engine 1 is shown in FIG. A throttle valve 3 is provided. A throttle valve opening ( _θTH ) sensor 4 is connected to the throttle valve 3, which detects the valve opening _θTH of the throttle valve 3 and outputs a corresponding throttle valve opening signal to the electronic control unit ( (hereinafter referred to as "ECU") 5. A fuel injection valve 6 is provided for each cylinder in the intake pipe 2 between the engine 1 and the throttle valve 3, slightly upstream of the intake valve (not shown), and each fuel injection valve 6 is connected to a fuel pump (not shown). and is electrically connected to the ECU 5.
The valve opening time of fuel injection is controlled by the drive signal from the.

On the other hand, an absolute pressure sensor (hereinafter referred to as "P _BA sensor") 8 is provided downstream of the throttle valve 3 via a pipe 7, and this P _BA sensor 8 detects the absolute pressure P _BA of the intake pipe 2. outputs a corresponding absolute pressure signal and sends it to ECU5.

The main body of the engine 1 is provided with an engine water temperature (Tw) sensor 9. This sensor 9 is made up of, for example, a thermistor, and is installed inside the circumferential wall of the engine cylinder filled with cooling water to detect and respond to the engine water temperature Tw. Sends a temperature signal to ECU5. or,
An engine rotation speed sensor (hereinafter referred to as "Ne sensor") 10 is arranged around a camshaft or crankshaft (not shown) of the engine 1, and the Ne sensor 10 receives an engine rotation speed signal, that is, 180 degrees of the engine crankshaft. A pulse signal generated at a predetermined crank angle position every ° rotation is output and sent to the ECU 5.

Further, other parameter sensors 11 such as an intake air temperature sensor, an atmospheric pressure sensor, an O ₂ sensor, etc. are connected to the ECU 5, and each sends a corresponding detection signal to the ECU 5.

Next, the operation of the fuel supply control device configured as described above will be explained.

The ECU 5 determines engine operating conditions such as high load range based on the engine parameter signals from each of the above-mentioned sensors, and also injects fuel according to the equation shown below in synchronization with the TDC signal according to the engine operating condition. Calculate the opening time T _Out of valve 6.

T _OuT = Ti×K ₁ + K ₂ …(1) Here, Ti is the reference value for the opening time of the fuel injection valve, and is based on the basic Ti map for normal operation or the WOT map for high load operation, which will be described later. The coefficient K ₁ and the variable K ₂ are determined by engine parameter signals from the various sensors mentioned above, respectively, to optimize various characteristics such as starting characteristics, exhaust gas characteristics, fuel consumption characteristics, acceleration characteristics, etc. according to engine operating conditions. It is calculated based on a predetermined calculation formula so that

ECU5 is the valve opening time calculated by the above formula (1)
A drive signal is output based on T _OuT and the fuel injection valve 6 is
Controls the opening of the valve.

FIG. 2 is a block circuit diagram of the internal configuration of the ECU 5, in which the engine rotational speed signal from the Ne sensor 10 is waveform-shaped by a waveform shaping circuit 501 and then processed by a central processing unit (hereinafter referred to as "CPU").
The signal 503 is supplied as an interrupt signal to start a control program described in the flowchart of FIG. 3, which will be described later, and is also supplied to the Me counter 502. The Me counter 502 counts the time interval from when the previous TDC signal was input from the Ne sensor 10 to when the current TDC signal was input.
Me is proportional to the reciprocal of the engine speed Ne. Me
Counter 502 supplies this count value Me to CPU 503 via data bus 510.

The throttle valve opening sensor 4, the P _BA sensor 8,
Each output signal from various sensors such as the engine water temperature sensor 9 is corrected to a predetermined voltage level by a level correction circuit 504, and then sequentially supplied to an A/D converter 506 by a multiplexer 505.
The A/D converter 506 sequentially converts the output signals from each sensor described above into digital signals and sends the digital signals to the CPU 503 via the data bus 510.
supply to.

The CPU 503 is further connected to a read-only memory (hereinafter referred to as "ROM") via a data bus 510.
507, is connected to a random access memory (hereinafter referred to as "ROM") 508 and a drive circuit 509, the RAM 508 temporarily stores the calculation results etc. of the CPU 503, and the ROM 507
A control program to be described later executed by the CPU 503, Ti maps during normal operation and high load operation,
It also stores WOT maps, set values representing engine load, delay times, etc.
The CPU 503 controls the fuel injection time T _OuT of the fuel injection valve 6 according to the various engine parameter signals mentioned above according to the control program stored in the ROM 507.
is calculated and this calculated value is supplied to the drive circuit 509 via the data bus 510. Drive circuit 509
supplies a control signal to the fuel injection valve 6 to open the fuel injection valve 6 according to the calculated value.

FIG. 3 is a flowchart showing the WOT map selection procedure.

First, in step 1, it is determined whether the engine speed Ne is larger than the high speed discrimination value N _WOT1 (for example, 4500 to 4700 rpm), and the determination result is affirmative (Yes).
In the case of , that is, the engine rotation speed Ne is the high rotation discrimination value
If N _WOT is 1 or higher, proceed to step 3. In step 3, it is determined whether the intake pipe absolute pressure _PBA is larger than the first high load determination value _PBAWOT2 . If the determination result is negative (No), that is, the absolute pressure in the intake pipe
If P _BA is smaller than the first high load discrimination value P _BAWOT2 (if the load is not high), proceed to step 9, set the flag η _DLY of the delay timer T _WOT to "0", and
Do not enrich the mixture by selecting the Ti map. If the determination result in step 3 is affirmative (Yes), that is, if the intake pipe absolute pressure P _BA is larger than the first high load determination value P _BAWOT2 (if the load is high),
Proceed to step 6 and set the flag η _DLY of the delay timer T _WOT to "2" to indicate that the load is high, and then in step 7 set the WOT map selection flag F _LGWOT to "1" and select the WOT map. This immediately enriches the mixture.

If the determination result in step 1 above is negative (No), that is, the engine rotation speed Ne is the high rotation determination value.
If it is smaller than N _WOT1 , in step 2 the engine rotation speed Ne is set to the low rotation discrimination value N _WOT0 (for example, 3500~
3700rpm). If the determination result is positive (Yes), that is, the engine rotation speed
If Ne is greater than the low-speed discrimination value N _WOT0 , the process proceeds to step 4, where it is determined whether the intake pipe absolute pressure P _BA is greater than the second high-load discrimination value P _BAWOT1 . If the determination result is affirmative (Yes), that is, if the intake pipe absolute pressure P _BA is larger than the second high load determination value P _BAWOT1 , then the load is high, so steps 6 and 7 described above are executed sequentially to map the WOT map. Select and execute mixture enrichment. If the determination result in step 4 is negative (No), that is, if the intake pipe absolute pressure P _BA is smaller than the second high load determination value P _BAWOT1 , then the load is not high, so execute step 9 above to perform the basic operation.
Select the Ti map and do not enrich the mixture.

If the judgment result in step 2 above is negative (No), that is, the engine rotation speed Ne is the low rotation judgment value.
If it is smaller than N _WOT0 , the process proceeds to step 5, where it is determined whether or not the intake pipe absolute pressure P _BA is larger than the third high load determination value P _BAWOT0 . The determination result is negative (No)
In this case, that is, if the intake pipe absolute pressure P _BA is smaller than the third high load determination value P _BAWOT0 , the aforementioned step 9 is executed, the basic Ti map is selected, and the mixture is not enriched.

If the determination result in Step 2 is negative (No), that is, the engine speed Ne is smaller than the low rotation determination value N _WOT0 , and the determination result in Step 5 is positive (Yes), that is, the intake pipe absolute pressure P _BA is If it is larger than the third high load discrimination value P _BAWOT0 , the intake pipe absolute pressure P _BA enters the delay (DLY) timer activation zone shown in Figure 4, and the WOT map is selected and mixed after a delay of the time set in the delay timer. In such a case, the method of the present invention does not uniformly delay the enrichment of the air-fuel mixture using a delay timer;
The vehicle speed V is checked at 0, and the delay timer is controlled to be involved or not involved depending on the value of the vehicle speed V. Figure 4 shows the delay timer operating zone, low load operating area, and high load operating area, and the intake pipe absolute pressure P _BA and engine speed Ne.
FIG. In the figure, the change characteristic of the intake pipe absolute pressure P _BA with respect to the rotational speed Ne when the throttle opening is θ _WOT under standard atmospheric pressure conditions is shown by a broken line. In step 10 described above, it is determined whether the vehicle speed V is greater than a predetermined value V _WOT (for example, 15 km/h). If the determination result is affirmative (Yes), that is, if the vehicle speed V is greater than the predetermined value V _WOT , the process proceeds to step 11, where it is determined whether the flag η _DLY of the delay timer T _WOT is 0 or not. Initially, the flag η _DLY is 0, so the determination result in step 11 is affirmative (Yes) and the process proceeds to step 12. In step 12, the delay timer T _WOT is reset and started. Then,
After setting the flag η _DLY to “1” to indicate that the delay timer T _WOT has started in step 13,
The basic Ti map is selected without executing step 9 described above, and the mixture is not enriched.
Since the flag η _DLY of the delay timer T _WOT is set to "1" from the next loop, the determination result in step 11 is negative (No), and in step 8, after the set time of the delay timer T _WOT has elapsed, Determine whether or not.

The determination result in step 10 above is negative (No).
In this case, that is, if the vehicle speed V is smaller than the predetermined value V _WOT , the process proceeds to step 8, and the delay timer T _{WOT is} set.
flag _ηDLY is set to ``2'', that is, the load is determined to be high and step 6 is executed, or the set time _TWOTDLY of the delay timer _TWOT , which was reset and started in step 12, has elapsed. Determine. If the determination result is affirmative (Yes), that is, if the determination result in step 3 or 4 becomes affirmative (Yes) at least once and step 6 is executed, the flag η _DLY of the delay timer T _WOT is set.
When "2" is set to "2" and the WOT map is selected, steps 6 and 7 described above are immediately executed in sequence to select the WOT map and enrich the air-fuel mixture.

The determination result in step 10 above is positive (Yes).
In this case, that is, if the vehicle speed V is larger than the predetermined value V _WOT , the process proceeds to step 11, but since the flag η _DLY of the delay timer T _WOT is set to "1" from the second loop onwards, the determination result of step 11 is is negative (No) and the determination result in step 8 is positive (Yes), that is, the flag η _DLY of the delay timer T _WOT is set to "2" and the load is determined to be high, and then the reset is performed in step 12. After the set time _TWOTDLY of the started delay timer _TWOT has elapsed, steps 6 and 7 described above are executed in sequence to select the WOT map and enrich the air-fuel mixture.

(Effects of the Invention) As detailed above, according to the fuel supply control method during high load operation of an internal combustion engine of the present invention, a set value representing the engine load is set for each predetermined range of engine speed of the internal combustion engine, In a fuel supply control method during high-load operation of an internal combustion engine, the method includes enriching the air-fuel mixture supplied to the engine when the actual engine load is determined to be higher than the set value. A low rotation discrimination value representing a low rotation range is set, and when the vehicle speed is equal to or higher than a predetermined value, the engine rotation speed is smaller than the low rotation discrimination value and the actual engine load is higher than the set value. When it is determined that
Execution of enriching the air-fuel mixture is delayed for a predetermined period of time, and when the vehicle speed is below a predetermined value, the engine speed is lower than the low rotation determination value and the actual engine load is higher than the set value. When it is determined that this is the case, the enrichment of the air-fuel mixture is immediately executed without delaying the predetermined time.

Therefore, it is possible to prevent the occurrence of torque shock during acceleration from low-load running, improve fuel economy, and improve acceleration performance when starting.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of a fuel supply control device for an internal combustion engine to which the method of the present invention is applied, FIG. 2 is a block circuit diagram of the internal configuration of the electronic control unit shown in FIG. 1, and FIG. A flowchart showing the WOT map selection procedure according to an embodiment of the invention, FIG. 4 shows the DLY timer operating zone,
FIG. 3 is a diagram showing a low-load operating region and a high-load operating region in terms of the relationship between intake pipe absolute pressure and engine rotation speed. 1... Internal combustion engine, 5... Electronic control unit, 6... Fuel injection valve, 8... Intake pipe absolute pressure sensor (engine load sensor), 10... Engine rotation speed sensor (Ne sensor).

Claims (1)

[Claims] 1 A set value representing the engine load is set for each predetermined range of engine speed of the internal combustion engine, and when the actual engine load is determined to be higher than the set value, the air-fuel mixture supplied to the engine is set. In a fuel supply control method during high-load operation of an increasingly rich internal combustion engine, a low rotation discrimination value representing a low rotation range of the engine rotation speed is set, and when the vehicle speed is equal to or higher than a predetermined value, the engine rotation speed is increased. When it is determined that the actual engine load is lower than the low rotation determination value and higher than the set value, execution of the enrichment of the air-fuel mixture is delayed for a predetermined time, and the vehicle speed is lower than or equal to a predetermined value. In this case, when it is determined that the engine speed is lower than the low rotation determination value and the actual engine load is higher than the set value, enriching the air-fuel mixture is delayed for the predetermined period of time. A method for controlling fuel supply during high-load operation of an internal combustion engine, characterized in that the method is executed immediately without any interruption.