JPH0472436A - Fuel injector of engine - Google Patents

Abstract

PURPOSE:To perform asynchronizing injection of a proper quantity by providing an asynchronizing injection forbidden time for a specified time, and not performing the asynchronzining injection even if an acceleration condition is detected during that time, after only using an intake pipe pressure sensor without using a throttle opening sensor, so as to detect acceleration condition followed by making asynchronizing injection. CONSTITUTION:A pressure detection means 3 which detects pressure in the intake pipe 2 of an engine 1 is provided, and a pressure average value is calculated by averaging output signals of the pressure detection means 3. When a deviation of a specified value or more from the calculated pressure average value is generated at the output signal of the pressure detection means, it is judged that an engine is under an acceleration condition, and fuel is injected asynchronizingly from an injector 4 by a first control means 6. Injection of asynchronous fuel is forbidden by the second control means 6 for a specified time of a specified stroke of the engine, after the asynchronous fuel is injected one. Consequently, the asynchronous injection of the optimum quantity can be performed in all acceleration conditions such as warming acceleration for which the acceleration time is long.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection device for an engine used in an automobile or the like, and particularly to a fuel injection means during engine acceleration.

[Prior Art] Conventionally, in fuel injection for engines such as automobiles, fuel is injected in an amount commensurate with the amount of air taken into the engine fuel chamber.
During transient conditions such as during acceleration, the air-fuel ratio of the mixture is Therefore, when an acceleration state is detected, the amount of fuel is increased. However, in order to quickly detect an acceleration state, a throttle opening sensor is generally used as the acceleration state detection means, and the amount of fuel is increased at regular intervals. An acceleration state is detected when the amount of change in the sensor output is equal to or greater than a predetermined value, and asynchronous injection is performed when the acceleration state occurs.

``Problem to be solved by the invention'' Since the fuel injection system for conventional engines was sophisticated as described above, a throttle opening sensor was required to detect the acceleration state, which caused the problem of increased cost. Therefore, an engine fuel injection device was proposed that could quickly detect the acceleration state without using a throttle opening sensor and maintain the optimal air-fuel ratio during acceleration using asynchronous injection.However, this device was a device that injected asynchronous fuel every time it detected an acceleration state, so for example, during slow acceleration with a long acceleration time, asynchronous fuel would be injected multiple times, resulting in excess fuel and exhaust gas and driver There was a problem in that it worsened the stability.

This invention was made in order to solve the above-mentioned problems, and provides an engine fuel injection system with excellent cost performance that performs asynchronous injection of the optimum amount in all acceleration conditions, such as during slow acceleration with a long acceleration time. The purpose is to obtain.

[Means for Solving the Problems] A fuel injection device for an engine according to the present invention includes a pressure detection means for detecting the pressure inside the intake pipe of the engine, and an output signal of the pressure detection means to calculate a pressure average value. , determining that the engine is in an acceleration state when the output signal value of the pressure detection means deviates from the calculated pressure average value by a predetermined value or more, and injecting fuel asynchronously when it is determined that the engine is in the acceleration state. The engine is equipped with a second control means that prohibits the injection of the asynchronous fuel for a predetermined period of time or a predetermined stroke of the engine after injecting the asynchronous fuel.

"Function" In this invention, the acceleration state is detected by the intake pipe pressure,
Asynchronous injection is performed when an acceleration state is detected, and asynchronous injection is then prohibited even if an acceleration state is detected for a predetermined time or a predetermined stroke of the engine.

[Example 1] An example of the present invention will be described below with reference to the drawings. 1st
FIG. 1 is a detailed diagram showing an embodiment of an engine fuel injection device according to the present invention. In Fig. 1, (1) is the engine, (2) is the intake pipe connected to the engine (1), and (2) is the intake pipe connected to the engine (1).
3) is a pressure sensor that detects the pressure inside the intake pipe (2). The output of the pressure sensor (3) is controlled by the A/
It is input to a D converter (61). (4) is the intake pipe (
2) is an injector W installed near each cylinder intake port, and fuel whose pressure is adjusted to a constant level is fed under pressure to the injector (4). (5) is a crank angle sensor that detects the rotation of the engine (1) as a pulse, and the output of the crank angle sensor (5) is the input circuit (6) of the control unit (6).
2). The control unit (6) includes a pressure sensor (3)
The required amount of fuel to be injected is calculated from the output of a crank angle sensor (5), etc., and a drive pulse having a pulse width corresponding to the calculated amount is generated to the injector (4). In the control section (6), an A/D converter (61) converts the analog signal of the pressure sensor (3) into a digital value and sends it to the microprocessor (63). The input circuit (62) converts the level of the pulse input signal from the crank angle sensor (5) and sends the output to the microprocessor (63). The microprocessor (63) is an A/D converter (61)
The amount of fuel to be supplied to the engine (1) is calculated based on the digital value and pulse signal obtained from the input circuit (62), and a drive pulse with a pulse width corresponding to the result is output to the injector (4). do. The control procedure and data of the microprocessor (63) are stored in advance in the ROM (64), or the RAM (65) temporarily stores data in the i-process. The output circuit (66) outputs the injector (4) according to the output of the microprocessor (63).
) to drive.

Next, the operation in the case of an all-cylinder simultaneous injection system of a four-stroke three-cylinder engine will be described. 2 to 4 are flowcharts showing the operation of the control section (6). FIG. 2 shows the main calculation section of the program. In step (201), the crank angle sensor (5) of FIG. The engine rotation speed Ne is calculated based on the crank angle sensor signal period T (see FIG. 5(a)) measured in step (401) of the crank angle interrupt processing. In step (202), the engine speed Ne obtained in step (201) and the intake pipe pressure pb obtained in step (301) in FIG.
(See Figure 5(c)).
The value of the volumetric efficiency η stored in (64) is determined by interpolation.

FIG. 3 shows a fixed time interrupt process by a timer, and for example, the output of the pressure sensor (3) is A/D converted in step (301>) every 5 milliseconds (+1 lsec). In step (403), the pressure sensor A/D conversion average value pb, . (See Figure 5(c))
In order to calculate , the pressure sensor A/D converted value Pbo that was A/D converted in step (302) is integrated. In step (303), as in the case of Stellaf Responsibility 302), in step (403) of FIG. 4, the pressure sensor A/D conversion average value P
In order to calculate b, , , A of step (301)
/Increments the value N of a counter that counts the number of D conversions. In step (304), in order to determine whether the engine is in an acceleration state, in step (301)
A predetermined value α (see FIG. 5(c)) is set for the D-converted pressure sensor A/D conversion value Pbo and the pressure sensor A/D conversion average value Pbm**a calculated in step (403) of FIG. If the pressure sensor A/D conversion value Pb, which was A/D converted in step (301), is small, the acceleration state is changed as shown by period T1 in FIG. is not determined, the acceleration state flag is cleared in step (305), and the process ends.

If period T2 in FIG. 5(c). As shown by T3 and T4, the pressure sensor A/D conversion value Pb7 is
/D is larger than the average value Pbmaan in Figure 5 (c
) is determined to be in an acceleration state at times tm+, tmz, and tmz, and proceeds to step (306).
Then, it is determined whether or not the vehicle was in an accelerated state last time, and if the previous time was also in an accelerated state, the process proceeds to Step 311), and if the previous time was not an accelerated state, the process proceeds to step (307).

In step (307), the acceleration state is determined as shown in FIG.
c) period T2. At T3 and T4, the asynchronous prohibition timer determines whether a predetermined time has elapsed after the asynchronous fuel injection. If the asynchronous prohibition timer is not 0, as shown in period T3 in FIG. 5(e), the process proceeds to step (311); if the asynchronous prohibition timer is O, as shown in periods T2 and T4 in FIG. 5(c), Then proceed to step (308).
Injector drive pulse width PW21 of asynchronous injection, P
W22 (see pulses P3 and P5 in FIG. 5(b)) is calculated, and in step (309) the injector (4) is driven to supply fuel to the engine (1). After driving the injector (4), an asynchronous prohibition time is set in the asynchronous prohibition timer in step (310), and an acceleration state flag is set in step (311). Then step (312)
Determine whether the asynchronous prohibition timer is 0 or not, and if it is 0, end the process as is, and if it is not 0, step (313)
decrements the asynchronous prohibition timer with , and then exits.

Furthermore, if the calculations in steps (312) and (313) are performed during a predetermined crank angle interruption by the crank angle sensor shown in FIG. Become.

In addition, in FIG. 5(b), Pi, P2. P4. P6 is a synchronous injection pulse, P3. P5 is an asynchronous injection pulse, and in FIG. 5(e), (11) to (14) are pressure sensors A/
D conversion average value calculation timing, tl, t2 ~ is +
, tJz, and tm3 to tn are interrupt processing timings for a certain period of time.

The cycle T of the crank angle sensor signal is measured in step (401) in FIG. 4, and used to calculate the rotational speed Ne in step (201) in FIG. In step (402), it is determined whether the current constant crank angle interrupt processing is the fuel injection timing, and if this is not the injection timing, the processing is terminated, and if this is the injection timing, the next step (402) is performed.
In step (403), the integrated values pb, u of the pressure sensor A/D conversion values obtained in step (302) in FIG. By dividing by the number of times N, the pressure sensor A/D
Converted average value pb, . Calculate. Since the current average value calculation has been completed, the A/D conversion integrated values pb, u are cleared in step (404), and the value N of the pressure sensor A/D converted value integrated number counter is cleared in step (405). . In step (406), step (301
Calculate the synchronous injection injector drive pulse width PH1 (see Figure 5(b)) from the pressure sensor A/D conversion value pb determined in ) and the volumetric efficiency η9 determined in step (202) in Figure 2. Then, in step (407), the injector (4
) is driven, fuel is supplied to the engine (1), and the process is completed.

In the above embodiment, the predetermined value α (see step (304) in FIG. 3) in the acceleration determination was set to a constant value, but the predetermined value α1 in FIG. As shown by α2, if the predetermined value is made smaller when the intake pipe pressure pb is low, and if the predetermined value is made larger when the intake pipe pressure pb is high, acceleration can be detected faster on the low pressure side where the intake pipe pressure ripple is small. This makes it possible to prevent erroneous detection of acceleration on the high pressure side where the ripple of the intake pipe pressure is large. In FIG. 6, Pbl is the predetermined value switching determination intake pipe pressure. Furthermore, step (304) in FIG.
) as α-f (Pb) as shown in Figure 7, it is possible to set the value according to the ripple of the intake pipe pressure from low pressure to high pressure, which enables faster acceleration detection in the entire operating range. I can do it.

[Effects of the Invention] As explained above, the present invention detects the acceleration state using only the intake pipe pressure sensor without using the throttle opening sensor, and after detecting the acceleration state and performing asynchronous injection, (or a predetermined stroke period), and asynchronous injection is not performed even if an acceleration state is detected during that time, so the optimal amount of asynchronous injection can be achieved in any acceleration state, such as slow acceleration with a long acceleration time. It is possible to obtain a fuel injection device for an engine that performs injection and has excellent cost performance.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an engine fuel injection device according to the present invention, FIGS. 2 to 4 are flowcharts for explaining the operation of the device shown in FIG. 1, and FIG. A time chart for explaining the operation of the device shown in FIG. 1, and FIGS. 6 and 7 are characteristic diagrams showing other examples of predetermined value setting. (1) Engine, (2) Intake pipe, (3) Pressure sensor, (4) Injector, (5) Crank angle sensor, (6) Control unit, (61)...^ /D converter, (62)...input circuit, (63)...microprocessor, (64), , ROM, (65)...
RAM, (66)...output circuit. Agent Zeng Wa Do Teru Figure 1 Broom three prongs 20 Figure 6 o, pzu^y〒Kairijiri (Pb)

Claims (1)

[Claims] Detecting the intake pipe pressure of the engine and calculating the fuel injection amount,
A fuel injection device for an engine that performs fuel injection in synchronization with a signal generated at every predetermined crank angle or every predetermined ignition includes a pressure detection means for detecting the pressure inside the intake pipe of the engine, and an output signal of the pressure detection means that is averaged. calculates a pressure average value, and determines that the engine is in an acceleration state when the output signal value of the pressure detection means deviates from the calculated pressure average value by a predetermined value or more; and when it is determined that the engine is in the acceleration state. The first control means injects fuel asynchronously, and the second control means prohibits injecting the asynchronous fuel for a predetermined time or for a predetermined stroke of the engine once the asynchronous fuel is injected. Features the engine's fuel injection system.