JPS62126242A - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable sequential ignition control over the entire load range of an engine by adding data-pulse conversion and distribution circuits to the outside of a micro computer. CONSTITUTION:The data of a fuel injection amount as operated on a micro computer 31 within a control circuit 30 on the basis of a machine operation condition, is inputted into data-pulse conversion circuits 33A-33D for each cylinder and temporarily memorized. On the other hand, a distribution circuit 32 distributes and outputs fuel injection timing signals as continuously inputted from a micro computer 31, toward the data-pulse conversion circuits 33A-33D for corresponding cylinders. Said circuits 33A-33D, upon receipt of the fuel injection timing signals from the distribution circuit 32 converts those signals into drive pulses having a pulse band corresponding to data memorized before hand, and outputs the drive pulses to drive circuits 34A-34D for the fuel injection valves 11 of corresponding cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a so-called sequential injection type electronically controlled fuel injection device that sequentially injects fuel into each cylinder of an internal combustion engine.

<Prior art> The sequential injection method described in Japanese Patent Application Laid-Open No. 57-8328 etc. can supply a mixture of fuel and air to each cylinder, and the combustion between the cylinders can be This has the advantage of eliminating variations in torque and reducing torque fluctuations.

By the way, in recent electronically controlled fuel injection systems using micro combinators, in those that adopt the sequential injection method, a microcomputer determines the fuel injection amount (
For example, in the case of a 4-cycle engine, the amount of fuel injected from the fuel injection valve of each cylinder every two rotations is calculated, and a drive pulse of 4t% with a pulse width corresponding to the calculated fuel injection amount is The fuel is distributed and supplied from one output terminal of the computer to the fuel injection valves of each cylinder via a drive circuit.

<Problems to be solved by the invention> However, in the conventional sequential injection method using the above-mentioned microcomputer,
Since the drive pulse signal for each cylinder was output from one output terminal of the microcomputer, it was necessary to continuously output the drive pulse signal for each cylinder with a large pulse width in short cycles at high speeds and high loads. Therefore, the pulses overlap with each other, making it impossible to distribute and supply drive pulse signals to each cylinder.

For this reason, under high-speed, high-load operating conditions that cause overlap between pulses, the system is switched to a method in which the drive pulse signal is output to the fuel injection valves of all cylinders at the same time to inject all cylinders at the same time. Ta.

However, when switching from sequential injection to simultaneous injection in all cylinders, the mixture ratio fluctuates due to the injection timing being changed at the moment of switching. 7ri occurs.

In addition, with simultaneous injection in all cylinders, the properties of the mixture vary due to the difference in the mixing time between fuel and air before reaching the combustion chamber between cylinders, which impairs the advantages of combustibility and injection. .

The above problem can be solved by using several cylinders with output terminals for outputting drive pulse signals, but there are restrictions on using a large number of output terminals because one microcomputer performs various electronic controls.

The present invention was developed in view of these conventional problems, and it is possible to perform sequential injection in full operation without increasing the number of microcomputer output terminals and using an inexpensive external circuit. An object of the present invention is to provide an electronically controlled fuel injection device for an internal combustion engine.

Means for Solving the Problems> For this reason, the present invention temporarily stores the data of the fuel injection amount calculated by a microcomputer manually, and then inputs the injection timing signal based on the data in synchronization with the human power of the injection timing signal. A data pulse conversion circuit for several cylinders converts the signal into a drive pulse signal and outputs it to the drive circuit of the fuel injection valve of the corresponding cylinder, and a data pulse conversion circuit for each cylinder outputs the signal from one output terminal of the microcomputer according to the injection order. The configuration includes a distribution circuit that manually distributes and outputs the injection timing signal to the data/pulse conversion circuit of the corresponding cylinder.

Function> Based on engine operating conditions such as engine speed and intake air flow rate, the microcomputer calculates the amount of fuel to be injected from the fuel injection valve of each cylinder. This calculated fuel injection amount data is manually input to the data/pulse conversion circuit of each cylinder and temporarily stored.

On the other hand, the injection timing for each cylinder is output from the output terminal of one microcomputer to the distribution circuit.

The distribution circuit distributes and outputs the injection timing signal of each cylinder, which is continuously input from the microcomputer, to the data/pulse conversion circuit of the corresponding cylinder.

The data/pulse conversion circuit that receives the injection timing signal from the distribution circuit converts the previously stored data into a drive pulse with a corresponding pulse width at the same time as the signal is input, and drives the fuel injector of the corresponding cylinder. Output to the circuit.

As a result, the fuel injection valve of the relevant cylinder is driven to open for a time corresponding to the pulse width, and an amount of fuel equal to the calculated amount is injected and supplied.

<Example> Embodiments of the present invention will be described below based on the drawings.

First, the overall configuration of an electronically controlled fuel injection system to which this embodiment is applied will be explained based on FIG. 1. An engine 1 includes an air cleaner 2. Intake duct 3. Air is drawn in via the throttle chamber 4 and the intake manifold 5.

The intake duct 3 is provided with an air flow meter 6 for detecting the intake air flow rate Q, and outputs a voltage signal corresponding to the intake air flow rate Q signal. In the throttle chamber 4,
A primary throttle valve 7 and a secondary throttle valve 8 that operate in conjunction with an accelerator pedal (not shown) are provided to control the intake air flow rate Q. In addition, these throttle valves 7
．． An auxiliary air passage 9 is provided which bypasses 8;
An idle control valve 10 is interposed in this auxiliary air passage 9. A fuel injection valve 1 is installed at the intake port of each cylinder of the engine 1.
1 is provided. The fuel injection valve 11 is an electromagnetic fuel injection valve that opens when the solenoid is energized and closes when the energization is stopped.The solenoid is energized by a drive pulse signal to open the valve, and pressure is supplied from a fuel pump (not shown). Fuel controlled to a predetermined pressure by a regulator is injected and supplied to the engine 1.

From engine 1, exhaust manifold 12. Exhaust duct 13
．． Exhaust gas is discharged via the three-way catalyst 14 and the muffler 15.

The exhaust manifold 12 is provided with an Ot sensor 16. This 0□ sensor 16 is the oxygen concentration in the atmosphere (constant)
outputs a voltage signal according to the ratio of the oxygen concentration in the exhaust gas and
The three-way catalyst 14 is a well-known sensor whose electromotive force changes suddenly when the air-fuel mixture is combusted at the stoichiometric air-fuel ratio.
This is a catalyst device that efficiently oxidizes or reduces O, HC, and NOx at around the stoichiometric air-fuel ratio of the air-fuel mixture and converts them into other harmless substances.

In addition, a crank angle sensor 17 is provided.

The crank angle sensor 17 includes a signal disc plate 19 provided on a crank pulley 18,
The teeth provided on the outer periphery output a reference signal every 120 degrees and a position signal every 1 degree, for example. Here, the engine speed N can be calculated by measuring the period of the reference signal.

The air flow meter 6, crank angle sensor 17 and O
The output signals from the t-sensor 16 are both input to a control unit 30 containing a microcomputer. Furthermore, the voltage of the battery 20 is directly applied to the control unit 30 via the engine key switch 21 as its operating power source and for detecting the power supply voltage. Furthermore, the control unit 30 includes
A water temperature sensor 22 that detects the engine cooling water temperature as necessary.
- Throttle sensor 23 including an idle switch that detects the throttle opening of the next throttle valve 7. Vehicle speed sensor 24 that detects vehicle speed. A signal from a neutral switch 25 or the like that detects the neutral position of the transmission is input.

FIG. 2 shows the configuration of the internal circuit of the control unit according to the present invention.

In the figure, a control unit 30c, a microcomputer (consisting of a CPU, ROM, RAM, input/output interface, A/D converter, address decoder, etc.) 31, a distribution circuit 32, and each cylinder (#1 to ##) are shown.
Data/pulse conversion circuits 33A to 33D for each cylinder (4 cylinders) and fuel injection valve drive circuits 34A to 34D for each cylinder
It is composed of:

Next, the action will be explained.

The microcomputer 31 calculates the fuel injection amount at a cycle of every two revolutions of the engine according to a program based on the flowchart (fuel injection amount calculation routine) shown in FIG.

To explain according to Fig. 3, step 1 (Sl in the figure)
It is written as (Similarly below), the basic fuel injection amount Tp (=K・Q/N) is calculated from the intake air flow rate Q obtained from the signal from the air flow meter 6 and the engine speed N obtained from the signal from the crank angle sensor 17. do.

In step 2, various correction coefficients cOEF are set as necessary.

In step 3, a voltage correction numerator s is set based on the voltage value of the battery 20.

In step 4, it is determined whether the λ control condition is met.

Here, if the λ control condition is not present, for example, in a high rotation, high load region, etc., the air-fuel ratio feedbank correction coefficient α is clamped to the previous value (or reference value α,), and the process goes from step 4 to step 8, which will be described later. move on.

In the case of the λ control condition, the output voltage V of the O2 sensor 16 is determined in steps 6 to 8. 2 and a slice level voltage corresponding to the stoichiometric air-fuel ratio v4. is compared to determine whether the air-fuel ratio is rich or lean, and the air-fuel ratio feedback correction coefficient α is set by integral control or proportional-integral control. Specifically, in the case of integral control, when the comparison in step 5 determines that the air-fuel ratio = rich (vo!>■1.t), the air-fuel ratio feedback correction coefficient α is set to a predetermined value with respect to the previous value in step 6. , and conversely, the air-fuel ratio = lean (Vow<
V... , ), in step 7 the air-fuel ratio feedback correction coefficient α is calculated by a predetermined integral (1
). In the case of proportional-integral control, in addition to this,
At the time of rich-lean reversal, an increase or decrease by a predetermined proportional bone (P) larger than the integral (1) is performed in the same direction as the integral (1).

Thereafter, in step 8, the fuel injection amount Ti injected from the fuel injection valve 11 of each cylinder is calculated according to the following equation.

T1=Tp-COEF-KA・α+Ts In this way, the fuel injection fiTi data calculated by the microcomputer 31 is sent to the data/pulse conversion circuit 33A for the #1 to #4 cylinders via the data bus at a predetermined timing. ~33D simultaneously and temporarily stored in these conversion circuits.

On the other hand, at a predetermined crank angle position of each cylinder detected based on the signal from the crank angle sensor 17, a fuel injection timing signal is output from one output terminal of the microcomputer 31 to the distribution circuit 32.

The distribution circuit 32 is constituted by a normal frequency dividing circuit or the like, and outputs the injection timing signal inputted from the microcomputer 31 to the data/pulse conversion circuit 33 of the corresponding cylinder according to the injection order.

In synchronization with the input of the injection timing signal, the data/pulse conversion circuit 33 converts the data of the fuel injection amount Ti inputted in advance from the microcomputer 31 into a drive pulse signal having a pulse width corresponding to Ti. The output signal is output to the drive circuit 34 of the cylinder.

As a result, the drive circuit 34 of the cylinder is activated and the corresponding fuel injection valve 11 is energized and opened for a time corresponding to Ti, thereby injecting and supplying an amount of fuel equal to the calculated amount.

In this way, fuel is sequentially injected and supplied to each cylinder according to a predetermined injection order.

In this way, the microcomputer 31 prevents the drive pulse signals for each cylinder from overlapping even at high speed and high load, and allows sequential injection control to be performed over the entire range. Therefore, it is possible to avoid the switching shock that occurs when switching between sequential injection and all-cylinder injection as in the past.
Injection is performed even at high speeds and high loads, resulting in good driving performance with little torque fluctuation and improved fuel efficiency.

Exhaust characteristics etc. are improved.

Further, since the number of output terminals of the microcomputer 31 used does not change, the microcomputer 31 does not need to be changed, and the cost can be as low as possible.

<Effects of the Invention> As explained above, according to the present invention, sequential injection control can be performed over the entire area of the engine by simply adding an inexpensive circuit outside the microcomputer. It is possible to avoid the shock caused by the switching, improve driving performance at high speeds and high loads, and improve fuel efficiency, exhaust characteristics, etc. as much as possible.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an internal combustion engine equipped with an electronically controlled fuel injection device according to an embodiment of the present invention, FIG. 2 is a circuit block diagram inside a control unit of the embodiment, and FIG. 3 is an embodiment of the invention. 2 is a flowchart showing a fuel injection amount calculation routine. 1... Engine 11... Fuel injection valve 30...
Control unit 31...Microcomputer 32...Distribution circuit 33A-33D...#1
~#4 cylinder data/pulse conversion circuit 34A~34
D... Drive circuit for #1 to #4 cylinders Patent applicant: Japan Electronics Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 3

Claims (1)

[Claims] A microcomputer calculates the fuel injection amount according to the engine operating conditions, and a drive pulse signal with a pulse width corresponding to the calculated fuel injection amount is used to drive the electromagnetic fuel injection valve provided in each cylinder of the engine. In an electronically controlled fuel injection system for an internal combustion engine, which outputs data to a circuit at a predetermined injection timing to drive a fuel injection valve to inject and supply fuel, data on the fuel injection amount calculated by a microcomputer is input. data/pulse conversion circuits for several cylinders that temporarily store the data and then convert it into a drive pulse signal based on the data in synchronization with the input of the injection timing signal and output it to the drive circuit of the fuel injection valve of the corresponding cylinder; A distribution circuit inputs an injection timing signal of each cylinder outputted from one output terminal of a microcomputer in accordance with the injection order, and distributes and outputs the signal to a data/pulse conversion circuit of a corresponding cylinder. An electronically controlled fuel injection system for internal combustion engines.