JPH0480218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an acceleration and asynchronous injection control method for an electronically controlled fuel injection engine, and is particularly applicable to an automobile engine equipped with an electronically controlled fuel injection device that senses intake pipe pressure. When accelerating an electronically controlled fuel injection engine, in addition to the preferred synchronous injection that is performed periodically in synchronization with the engine rotation, asynchronous injection is performed during sudden acceleration when the differential value of the intake pipe pressure is large. This invention relates to improvements in asynchronous injection control methods.

2. Description of the Related Art One of the methods for supplying an air-fuel mixture at a predetermined air-fuel ratio to the combustion chamber of an internal combustion engine such as an automobile engine uses an electronically controlled fuel injection device. In this system, injectors for injecting fuel into the engine are arranged in the intake manifold of the engine, for example, in several engine cylinders, and the valve opening time of the injectors is detected from the engine operating state, for example, the intake pipe pressure. By controlling according to the load, engine speed, etc., a mixture having a predetermined air-fuel ratio is supplied to the engine combustion chamber.

In automobile engines equipped with such electronically controlled fuel injection devices, synchronous injection, which is performed periodically in synchronization with engine rotation, usually results in a fuel shortage during acceleration, causing the air-fuel ratio to temporarily become over-lean. As a result, poor acceleration such as breathing and sluggishness occurs. Therefore, for example, during sudden acceleration when the second differential value of the intake pipe pressure is large, in addition to the synchronous injection,
So-called asynchronous injection is performed in which a predetermined amount of fuel is injected regardless of the crank angle of the engine.

However, even during steady operation, when the engine rotates at low speeds, where fluctuations in intake pipe pressure are large due to intake pipe pulsations, even slight acceleration causes a drop in intake pipe pressure.
If the differential value exceeds the sudden acceleration judgment value, it will be judged as sudden acceleration and asynchronous injection will be performed, resulting in an overly rich mixture, which may lead to an increase in exhaust emissions and a decrease in drivability. Ta. In order to solve this problem, it is possible to uniformly increase the sudden acceleration judgment value, but in that case, there is a risk that the acceleration judgment at high speed rotation will be delayed and appropriate asynchronous injection will not be performed. It was hot.

The present invention has been made in order to solve the above-mentioned conventional problems, and in particular, it does not erroneously determine that slow acceleration at low engine speed rotation is sudden acceleration, and therefore,
It is an object of the present invention to provide a method for controlling asynchronous injection during acceleration of an electronically controlled fuel injection engine that can accurately control the air-fuel ratio during acceleration.

The present invention provides acceleration of an electronically controlled fuel injection type engine in which, in addition to synchronous injection performed periodically in synchronization with engine rotation, asynchronous injection is performed during sudden acceleration when the differential value of intake pipe pressure is large. In the time-asynchronous injection control method, as summarized in Figure 1, there is a procedure for determining the differential value of the intake pipe pressure, and a sudden acceleration judgment value that is large when the engine rotation speed is low, at least according to the engine rotation speed. a procedure for determining whether the differential value of the intake pipe pressure exceeds the sudden acceleration determination value, and a procedure for executing asynchronous injection when the differential value of the intake pipe pressure exceeds the sudden acceleration determination value. The above objective is achieved by including the following.

Further, the differential value is set as a second-order differential value of the intake pipe pressure, so that a more accurate sudden acceleration determination can be made.

In the present invention, the sudden acceleration determination value is determined at least according to the engine rotation speed, and is large when the engine rotation speed is low, so that it is possible to erroneously judge a slow acceleration at a low engine speed as a sudden acceleration. Therefore, the air-fuel ratio during acceleration can be accurately controlled.

Embodiments of an automobile engine equipped with an intake pipe pressure sensing type electrically controlled fuel injection device employing the acceleration asynchronous injection control method for an electronically controlled fuel injection engine according to the present invention will be described below with reference to the drawings. will be explained in detail.

In this embodiment, as shown in FIG. 2, an intake air temperature sensor 12 for detecting the temperature of intake air taken in from the outside and a throttle body 14 are provided.
Accelerator pedal located in the driver's seat (not shown)
A throttle valve 16 for controlling the flow rate of intake air, which is opened and closed in conjunction with the throttle valve 16, a throttle sensor 18 for detecting the opening degree of the throttle valve 16, and a throttle sensor 18 for preventing intake interference. A surge tank 20 and an intake pipe pressure sensor 22 for detecting the pressure of intake air in the surge tank 20
, an injector 26 disposed in the intake manifold 24 for intermittently injecting pressurized fuel toward the intake port of each cylinder of the engine 10; A spark plug 28 for ignition and an exhaust manifold 3
0 and the high voltage ignition 2 generated by the ignition coil 32.
The next signal is sent to the spark plug 28 of each cylinder of the engine 10.
A distributor shaft 34 that rotates in conjunction with the rotation of the crankshaft of the engine 10 for distributing power to the
a crank angle sensor 36 built into the distributor 34 for detecting the rotational state of the engine 10 from the rotational state of the distributor shaft 34A;
A water temperature sensor 38 disposed on the cylinder block 10B of the engine 10 for detecting the engine cooling water temperature, and an engine rotation determined from the engine load detected from the output of the intake pipe pressure sensor 22 and the output of the crank angle sensor 36. The synchronous injection time is calculated according to the speed, etc., and a valve opening time signal is periodically output to the injector 26 in synchronization with the engine rotation to perform synchronous injection, and the double differential value of the intake pipe pressure suddenly accelerates. An electronic control unit (hereinafter referred to as ECU) 40 for performing asynchronous injection when sudden acceleration is detected because the determination value has been exceeded;
It consists of

The ECU 40, as shown in detail in FIG.
A central processing unit (hereinafter referred to as CPU) 40A consisting of a microprocessor, for example, for performing various calculation processes, and a read-only memory (hereinafter referred to as CPU) for storing control programs and various data, etc.
a random access memory (hereinafter referred to as RAM) 40 for temporarily storing calculation data etc. in the CPU 40A;
C, an analog-to-digital converter (hereinafter referred to as "analog-to-digital converter") equipped with a multiplexer function for converting analog signals input from the intake air temperature sensor 12, intake pipe pressure sensor 22, water temperature sensor 38, etc. into digital signals and sequentially inputting the digital signals. (referred to as A/D converter)4
0E, and digital signals input from the throttle sensor 18, crank angle sensor 36, etc., and according to the calculation results of the CPU 40A,
For connecting an input/output port (hereinafter referred to as I/O port) 40F with a buffer function for outputting control signals to the injector 26, etc., and each of the component devices to transfer data and instructions. It consists of a common bus 40G.

The action will be explained below.

The asynchronous injection during acceleration in this example is the fourth
The interrupt routine is executed at predetermined time intervals as shown in the figure. That is, the routine advances to step 110 every predetermined time period, and the intake pipe pressure PM obtained from the output of the intake pipe pressure sensor 22 is input. Next, the process proceeds to step 112, where the second differential value DDPM of the intake pipe pressure PM is calculated using, for example, the following equation.

DDPM=(PM-PM _-1 )-(PM _-1 -PM _-2 )...(1) Here, PM is the intake pipe pressure input this time,
PM _-1 is the previously input intake pipe pressure, PM _-2
is the intake pipe pressure input the time before last.

Next, the process proceeds to step 114, where it is determined whether the engine rotational speed NE determined from the output of the crank angle sensor 36 exceeds a predetermined value A. If the determination result is positive, that is, if it is determined that the engine is rotating at medium to high speed, the process proceeds to step 116, where it is determined whether the intake pipe pressure PM exceeds a predetermined value P. If the determination result is positive, that is,
When it is determined that the load is medium to high, the step
Proceed to step 118 and set the normal value C as the sudden acceleration judgment value L.
Put in.

On the other hand, if the judgment result in step 114 or 116 is negative, that is, if it is judged that the engine is rotating at a low speed or under a light load, the process proceeds to step 120, where a sudden acceleration judgment value L is set as a relatively large value D
Insert (>C).

After completing step 118 or 120 above, step 122
Then, it is determined whether the second order differential value DDPM of the intake pipe pressure calculated in step 112 exceeds the sudden acceleration determination value L or not. When the determination result is positive, that is, when it is determined that the vehicle is rapidly accelerating,
Proceeding to step 124, asynchronous injection is performed and the routine ends. On the other hand, if the determination result in step 122 is negative, this routine is ended without performing asynchronous injection.

In this example, the second-order differential value DDPM of the intake pipe pressure at low engine speed rotation and the sudden acceleration judgment value L (=
FIG. 5 shows the relationship D), and FIG. 6 shows an example of the relationship between the second-order differential value DDPM of the intake pipe pressure and the sudden acceleration determination value L (=C) when the engine rotates at high speed. Fifth
As is clear from the diagram and FIG. 6, in this embodiment, the sudden acceleration determination value L is a large value D during low speed rotation
Therefore, even though the second-order differential value DDPM of the intake pipe pressure fluctuates greatly during low-speed rotation, it is possible to accurately determine that the load has shifted to high due to sudden acceleration. On the other hand, if the judgment value C for high-speed rotation is used as it is for low-speed rotation, an erroneous sudden acceleration judgment will be made even during slow acceleration, and inappropriate asynchronous injection will occur, causing the air-fuel mixture to It had become too dense.

In this embodiment, the sudden acceleration determination is made in accordance with the second-order differential value DDPM of the intake pipe pressure PM, so that the sudden acceleration determination can be made more accurately.
Note that the method for determining sudden acceleration is not limited to this, and it is also possible to determine sudden acceleration according to the first-order differential value of the intake pipe pressure.

In the above embodiment, the sudden acceleration determination value L
is changed according to the engine rotational speed NE and the intake pipe pressure PM, but the method of changing the sudden acceleration determination value is not limited to this, for example, it may be changed only according to the engine rotational speed, It is possible to change it according to the engine rotation speed, intake pipe pressure, and vehicle running speed.

As explained above, according to the present invention, it is possible to avoid erroneously determining that slow acceleration at low engine speed rotation is sudden acceleration. Therefore, unnecessary asynchronous injection is not performed, the air-fuel ratio can be accurately controlled during acceleration, and it is possible to prevent an increase in exhaust emissions and deterioration of drivability due to an overly rich mixture. It has this excellent effect.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the asynchronous injection control method during acceleration of an electronically controlled fuel injection engine according to the present invention, and FIG. 2 is a flowchart showing an electronically controlled fuel injection method using intake pipe pressure sensing in which the present invention is adopted. FIG. 3 is a cross-sectional view including a partial block diagram showing an embodiment of an automobile engine equipped with the device; FIG. 4 is a block diagram showing the configuration of the electronic control unit used in the above embodiment; Similarly, FIG. 5 is a flowchart showing a time interrupt routine for performing asynchronous injection, and FIG. Similarly, the diagram shown in FIG. 6 is a diagram showing an example of the relationship between the second-order differential value of the intake pipe pressure and the sudden acceleration determination value when the engine rotates at high speed. PM...Intake pipe pressure, NE...Engine speed, L...Sudden acceleration judgment value, 10...Engine, 2
2...Intake pipe pressure sensor, 26...Injector, 36...Crank angle sensor, 40...Electronic control unit (ECU).

Claims (1)

[Claims] 1. An electronically controlled fuel injection system that performs asynchronous injection during sudden acceleration when the differential value of the intake pipe pressure is large, in addition to synchronous injection that is periodically performed in synchronization with engine rotation. In a method for controlling asynchronous injection during engine acceleration, a procedure for determining a differential value of intake pipe pressure;
At least according to the engine rotation speed, a procedure for determining a sudden acceleration determination value that becomes large when the engine rotation speed is low; and a procedure for determining whether a differential value of the intake pipe pressure exceeds the sudden acceleration determination value; 1. A method for controlling asynchronous injection during acceleration of an electronically controlled fuel injection engine, comprising: executing asynchronous injection when a differential value of intake pipe pressure exceeds a sudden acceleration determination value. 2. The asynchronous injection control method during acceleration of an electronically controlled fuel injection type engine according to claim 1, wherein the differential value is a second-order differential value of intake pipe pressure.