JPH0629584B2 - Fuel control device for automobile engine - Google Patents

Description

The present invention relates to a fuel control device for an automobile engine.

[Conventional technology]

2. Description of the Related Art Conventionally, in an automobile engine, the driver lightly operates the accelerator pedal to increase the engine speed when the vehicle is stopped and power is not transmitted from the engine (usually called idling). Is done.

[Problems to be solved by the invention]

Then, in the conventional automobile engine, after this idling is performed and the throttle valve connected to the accelerator pedal is opened to increase the engine speed, the throttle valve returns to the fully closed position (minimum opening position). When this happens, the inside of the intake passage on the downstream side of the throttle valve becomes extremely negative pressure state, and the exhaust gas in the exhaust passage fills not only the combustion chamber but also the intake system (intake manifold or surge tank) based on the generation of this negative pressure. When the engine speed drops to the idle speed in this state, the combustion state of the air-fuel mixture deteriorates due to the effect of exhaust gas remaining in the combustion chamber and the intake system, and the engine speed becomes unstable. Then, the engine speed may drop abnormally or a stall may occur in the worst case.

[Means for solving problems]

The present invention has been proposed in view of the above, and is an engine mounted on an automobile, a fuel supply device that is provided in a combustion chamber or an intake passage of the engine and supplies fuel to the combustion chamber, and the intake passage. A throttle valve installed in the vehicle, a first sensor for detecting whether or not the vehicle is in a stopped state, and a second sensor for detecting the number of revolutions of the engine,
A third sensor that detects whether or not the throttle valve is at the minimum opening position, and the vehicle is in a stopped state based on the outputs of the first sensor, the second sensor, and the third sensor, and Restricting fuel supply from the fuel supply device when it is determined that the engine speed is equal to or higher than a predetermined speed, the engine speed is decreasing, and the throttle valve is at the minimum opening position Another object of the invention is to provide a fuel control device for an automobile engine, which is provided with a control means for issuing a signal for shutting off.

[Action]

According to the present invention, when the engine is blown idle when the vehicle is stopped, the start of the state in which the engine speed decreases after the accelerator pedal is returned is detected to stop or suppress the fuel supply to the engine combustion chamber. , The generation of exhaust gas after combustion at this time is stopped or suppressed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, an engine E has an intake passage 2 and an exhaust passage 3 which communicate with a combustion chamber 1, and the intake passage 2 and the combustion chamber 1 are controlled to communicate with each other by an intake valve 4 and are connected to an exhaust passage 3. Communication with the combustion chamber 1 is controlled by an exhaust valve 5.

Further, the intake passage 2 is provided with an air cleaner 6, a throttle valve 7 connected to an accelerator pedal operated by a driver, and an electromagnetic fuel injection valve (injection valve) 8 sequentially from the upstream side, and the exhaust passage 3 is provided with the air cleaner 6. Is provided with a catalytic converter 9 for purifying exhaust gas and a muffler (not shown) in order from the upstream side thereof.

The solenoid valve 8 is provided for each cylinder in the intake manifold portion.

With such a configuration, the air taken in through the air cleaner 6 according to the opening degree of the throttle valve 7 is mixed with the fuel from the solenoid valve 8 in the intake manifold portion so as to have an appropriate air-fuel ratio, and is ignited in the combustion chamber 1. After the plug is ignited at an appropriate timing to be burned to generate engine torque, the air-fuel mixture is discharged as exhaust gas into the exhaust passage 3, and the catalytic converter 9 discharges CO, HC, After the three harmful components of NOx are purified, they are silenced by the muffler and released to the atmosphere.

Further, various sensors are provided to control the engine E. First, on the intake passage 2 side, an air flow sensor 11 for detecting the intake air amount from the Karman vortex information, an intake temperature sensor 12 for detecting the intake air temperature, and an atmospheric pressure sensor 13 for detecting the atmospheric pressure are provided in the portion where the air cleaner 6 is provided. The throttle valve 7 is provided with a potentiometer-type throttle sensor 14 for detecting the opening degree of the throttle valve 7, an idling state (that is, the driver does not depress the accelerator pedal, and the throttle valve 7 is An idle switch 15 is provided as a third sensor for detecting the state (at the minimum opening position).

Further, on the exhaust passage 3 side, an oxygen sensor 17 that detects the oxygen concentration in the exhaust gas and a temperature sensor 18 that detects the temperature of the catalytic converter 9 are provided.

Further, as other sensors, a water temperature sensor 19 for detecting the engine cooling water temperature and a vehicle speed sensor 20 (see FIG. 2) as the first sensor for detecting the vehicle speed are provided, and as shown in FIG. A crank angle sensor 21 that detects an angle (this crank angle sensor 21 also serves as a rotation speed sensor as a second sensor that detects an engine rotation speed) and a top dead center of a first cylinder (reference cylinder). Each TDC sensor 22 is provided in the distributor.

Then, the detection signals from these sensors 11 to 22 are
It is adapted to be input to an electronic control unit (ECU) 23.

A voltage signal from a battery sensor 25 that detects the voltage of the battery 24 and a signal from an ignition switch (key switch) 26 are also input to the ECU 23.

The hardware configuration of the ECU 23 is as shown in FIG. 2, and the ECU 23 is a main part of the CPU 27.
The intake air temperature sensor 1 is connected to the CPU 27.
2, the detection signals from the atmospheric pressure sensor 13, the throttle sensor 14, the oxygen sensor 17, the temperature sensor 18, the water temperature sensor 19 and the battery sensor 25 are input to the interface 2.
8 and the A / D converter 30, and the detection signals from the idle switch 15, the vehicle speed sensor 20 and the ignition switch 26 are input to the input interface 2.
9, the detection signals from the air flow sensor 11, the crank angle sensor 21, and the TDC sensor 22 are directly input to the input port.

Further, the CPU 27 stores, via a bus line, a ROM 31 that stores program data for various controls and preset fixed value data, and an R that is updated and sequentially rewritten.
A battery backup RAM (B that is backed up by holding the stored contents while the battery 24 is connected by the AM 32 and the battery 24
Data is exchanged with the URAM) 33.

Focusing only on fuel injection control, the CPU 27 outputs a fuel injection control signal, which is calculated mainly based on the two programs described later, through the driver 34. For example, the solenoid valve 8 of each cylinder is used for its stroke. It is designed to drive sequentially according to the phase.

The fuel injection control signal is obtained by adding various correction data according to the operating state to the basic drive time data set according to the intake air amount, in which case the basic drive time data is determined by the crank It is obtained in the solenoid valve drive routine executed by using the crank angle signal from the angle sensor 21 as an interrupt, while the various correction data are obtained in the main routine that is always executed when the program is not executed by the interrupt. To be

Also, depending on the operating state, there are times when fuel supply is not performed, but such an operating state is detected in the main routine described above, and the detection result is the fuel injection stop in the solenoid valve drive routine. Used as an instruction.

The main routine and the solenoid valve drive routine will be described below.

In FIG. 3, in the main routine which is started when the key switch is turned on, first, at step A1, each address of the RAM 32 is initialized.
Next, in step A2, the operation state information is read from various sensors, and the read information is RA
It is input to each address of M32. Next, at step A3, it is judged if the idle switch 15 is on. When the idle switch 15 is not on, that is, when the driver is operating the accelerator pedal and the throttle valve 7 is on the open side of the minimum opening position, the second rotation speed address N2 of the RAM 32 is determined in step A4.
Is reset to 0. The second rotation speed address N2 holds the rotation speed data used in the previous main routine, and the input to this address N2 is performed in step A12 and step A14 described later. Then, after step A4, step A5
At, the fuel cut flag is reset to command the fuel supply. The fuel cut flag is identified by whether the data at the predetermined address in the RAM 32 is 1 or 0. In this step, the data is input to the address. Then, when the operation of step A5 ends, next, in step A13, the above-described various correction data are obtained. The correction data obtained here includes a water temperature correction coefficient Kwt set based on the output of the water temperature sensor 19, an air-fuel ratio feedback correction coefficient Kaf set based on the output of the oxygen sensor 17, and an output of the intake air temperature sensor 12. The intake air temperature correction coefficient Kat set based on the output, the atmospheric pressure correction coefficient Kap set based on the output of the atmospheric pressure sensor 13, the acceleration correction coefficient Kac set based on the output of the throttle sensor 14, the battery sensor 2
There are invalid time data Td and the like set based on the output of FIG. When the operation of step A5 is completed, the series of operations from step A2 is executed again unless a program execution instruction by an interrupt is issued.

On the other hand, in step A3, when the idle switch 15 is on, that is, when the driver does not operate the accelerator pedal and the throttle valve 7 is at the minimum opening position,
In step A6, the engine speed (this data is R
It is stored in the address Nr of AM32. ) Is larger than the set rotation speed Ns (for example, 1500 rpm). When it is determined that the value is larger, the process goes to step A7, the data at the address N2 is reset like step A4, and then the fuel cut flag is set at step A8 to command the fuel supply stop, and the process goes to step A12.

Further, when it is determined in step A6 that the engine speed is equal to or lower than the set speed Ns, step A
In 9, the engine speed is the idle upper limit speed Ni as a predetermined speed (from the idle speed 100 rpm ~
It is set high about 150 rpm. ) It is determined whether or not it is smaller, and when it is determined that it is smaller, the process proceeds to steps A4 and A5 to instruct fuel supply. Further, when it is determined that the engine speed is equal to or higher than the idle upper limit speed Ni, it is determined in step A10 whether the vehicle speed is 0, that is, whether the vehicle is stopped, and the vehicle is not stopped. When the determination is made, the process goes to step A5 through step A4 to instruct the fuel supply. Further, when it is determined in step A10 that the vehicle is stopped, the engine speed data is compared with the data of address N2 in step A11. Here, by comparing the rotational speed information read in the main flow this time with the rotational speed information read in the previous main flow, it is possible to determine whether or not the engine rotational speed is currently decreasing. If the engine speed data is equal to or higher than the data at the address N2 in the determination at step A11, the latest engine speed data is input to the address N2 at step A14 on the assumption that the decrease in the engine speed is not detected. The process proceeds to step A5 to command the fuel supply. On the other hand, if it is determined in step A11 that the engine speed data is smaller than the data at address N2, it is determined that the engine speed is decreasing, and the latest engine speed data is input to address N2 in step A12 before fuel supply. The process proceeds to step A8 to instruct the stop.

It should be noted that the ECU 23 is configured to set a fuel cut flag in step A8 for instructing fuel supply stop based on the determination results in steps A3, A10 and A11 in this main routine, and serves as a fuel control means. It has a function.

The above is the description of the main routine, but the following description is about the solenoid valve drive routine.

In FIG. 4, in the case of a four-cylinder engine, the solenoid valve drive routine operates by crank pulse interruption every 180 °. First, at step b1, it is judged whether or not the fuel cut flag is set, and it is set. If so, the fuel is not supplied, and therefore the routine directly returns and waits for the next crank pulse interruption. On the other hand, if it is determined that the fuel cut flag is reset, in step b2, the crank angle is determined based on the number of Kalman pulses generated between the previous crank pulse and the current crank pulse and the cycle data between the Kalman pulses. 18
The intake air amount information Qcr (Q / N) per 0 ° is set.

Then, in the next step b3, the basic drive time (basic valve opening time) Tb of the solenoid valve 8 is set according to this Qcr, and then in step b4 the solenoid valve drive time Tinj is set to Tinj = Tb × Kwt × Kat. It is obtained by the calculation of × Kap × Kac × Kaf + Td, and this Tinj is set in the injection timer in step b5, and then this injection timer is triggered in step b6. Then, when triggered in this manner, fuel is injected from the solenoid valve 8 only during the time Tinj. When the fuel supply is executed, this solenoid valve drive routine is in a state of waiting for the next crank pulse interrupt when step b6 is completed.

According to the above configuration, when the idle switch 15 is off, fuel is supplied according to the operating state of the engine, and when the idle switch 15 is on and the engine speed is higher than the set speed Ns, the vehicle speed is increased. Regardless, the fuel supply is stopped. Also, idle switch 1
5 is on, the engine speed is equal to or lower than the set speed Ns, and fuel is always supplied according to the operating state of the engine while the vehicle is traveling. Further, even when the vehicle is stopped, the fuel is supplied as usual when the idle switch 15 is on and the engine speed is lower than the idle upper limit speed Ni, that is, during the idle operation while the vehicle is stopped. On the other hand, when the vehicle is stopped and the idle switch 15 is on and the engine speed is equal to or higher than the idle upper limit speed Ni, the fuel supply is stopped.

That is, when the vehicle is stopped, when the driver lightly depresses the accelerator pedal while the vehicle is stopped and then stops the depression, the opening of the throttle valve 7 is as shown in FIG. The amount of fuel supplied to the engine E changes as shown by the solid line in FIG. 5B. That is, when the air is blown while the vehicle is stopped, the fuel supply is temporarily stopped until the engine speed returns to the vicinity of the idle speed. Therefore, after the air blow, the intake negative pressure is applied to the exhaust passage 3 side. The gas returned to the intake passage 2 side is mainly air, and a sufficient amount of oxygen is secured in the combustion chamber 1 and the intake passage 2 even when the engine speed returns to the idle speed.

Therefore, the exhaust gas after combustion is exhausted in the combustion chamber 1 and the intake passage 2 at the time of the idling return immediately after the idling while the vehicle is stopped.
It is possible to prevent the occurrence of problems such as a drop in the engine speed and a stall immediately after the idling speed is restored, without filling the inside.

The solid lines in FIGS. 5C and 5D show how the pressure in the intake passage on the downstream side of the throttle valve 7 and the engine speed change in the above embodiment. (In FIGS. 5B to 5D, the state of the conventional device, that is, the state where the fuel supply is not stopped immediately after idling while the vehicle is stopped is shown by a broken line. When the engine speed once rises and then approaches the idling speed again, the intake passage pressure and the engine speed do not fluctuate significantly. The state of engine stall in the conventional device is shown.) In the above embodiment, the fuel supply is stopped immediately after the vehicle is stopped and the fuel supply is stopped, but the fuel supply may be restricted (the supply amount may be reduced). Good.

〔The invention's effect〕

According to the present invention, sufficient fresh air can be ensured in the engine combustion chamber and the intake system even immediately after blown air (temporary opening operation of the throttle valve) while the vehicle is stopped, and combustion is stabilized. The occurrence of engine stalls is prevented.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an engine according to an embodiment of the present invention, FIG. 2 is a block diagram showing hardware of a control system of the engine, and FIGS. 3 and 4 are control of the control system. 5A to 5D are graphs for explaining the operation of the above-described embodiment while comparing it with the operation of the conventional example. E ... Engine, 2 ... Intake passage, 7 ... Throttle valve, 8 ... Electromagnetic fuel injection valve, 15 ... Idle switch, 20 ... Vehicle speed sensor, 21 ... Crank angle sensor,
23 ... ECU

Claims (1)

[Claims] 1. An engine mounted on an automobile, a fuel supply device provided in a combustion chamber or an intake passage of the engine for supplying fuel to the combustion chamber, a throttle valve interposed in the intake passage, and A first sensor for detecting whether or not the vehicle is stopped, a second sensor for detecting the number of revolutions of the engine, and a third sensor for detecting whether or not the throttle valve is at the minimum opening position. Of the sensor and the outputs of the first sensor, the second sensor, and the third sensor, the vehicle is in a stopped state, the rotation speed of the engine is equal to or higher than a predetermined rotation speed, and the rotation speed of the engine is And a control means for issuing a signal for limiting or interrupting fuel supply from the fuel supply device when it is determined that the throttle valve is at the minimum opening position and the throttle valve is at the minimum opening position. Fuel control system of car engine