JPH048846A - Electronically controlled fuel injection system for internal combustion engines - Google Patents

Abstract

PURPOSE:To prevent deterioration in engine performance by monitoring deterioration in parts interposed in an engine air intake system, and in deterioration, by correcting an engine load parameter acquired from an opening area of the engine air intake system according to the degree of deterioration. CONSTITUTION:In an engine air intake system, an auxiliary air passage in which an electromagnetic type auxiliary air control valve A duty-controlled by bypassing a throttle valve is interposed is provided. One of engine load parameters is calculated by a means B, and a fuel injection amount is controlled by a means C based on this calculated value. In an above device, an idle driving is detected by a means D. Also, a duty to the auxiliary air control valve A is set by a means E based on the engine driving state detected in idling. Moreover, when an actual set duty is larger than a predetermined duty, deterioration in parts interposed in the engine suction system is judged by a means F. At the judgment of parts deterioration, the engine load parameter is corrected according to the difference between the actual duty and the predetermined duty.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronically controlled fuel injection system for an internal combustion engine, and particularly to one that calculates the engine load using the opening area of the engine intake system.

<Prior art> Conventionally, in an electronically controlled fuel injection system for an internal combustion engine, the intake air flow rate Q is detected as the state quantity of the intake air, and from this and the engine rotational speed N, the basic fuel injection amount Tp = -Q /N
(K is a constant), or the intake pressure (intake negative pressure) PB is detected as the state quantity of the intake air, and the basic fuel injection amount Tp is computed based on this. Note that the method using the intake air flow rate Q is called L-Jetro, and the method using intake pressure PB is called D-Jetro. Then, various correction coefficients C0EF based on water temperature etc., air-fuel ratio feedback correction coefficient LAMBO
A and corrected by a voltage correction numerator S based on the battery voltage, the final fuel injection amount Ti=Tp−COE F −
Calculate LAMBDA+Ts.

Then, at a predetermined timing synchronized with the engine rotation, a drive pulse signal in the pulse corresponding to the fuel injection amount Ti is outputted to the electromagnetic fuel injection valve, thereby injecting and supplying fuel to the engine.

However, the fuel injection amount Ti corresponds to the engine demand during steady operation, and during transient operation, for example during acceleration, the air-fuel ratio becomes lean due to a delay in the transportation of liquid fuel (wall flow) adhering to the inner wall of the intake passage. As a result, the engine output did not respond well during acceleration, resulting in poor acceleration performance.

Therefore, the total opening area AA of the engine intake system (opening area of the main intake passage controlled by the throttle valve and the idle control valve,
A transient correction amount is set based on the amount of change in the basic fuel injection amount Tp (engine load) calculated from the engine rotational speed N (opening area of each auxiliary air passage controlled by the air regulator), and this transient correction amount is used. The final fuel injection amount T
It has been proposed to improve the air-fuel ratio control accuracy, output responsiveness, etc. not only during acceleration but also during transient operation, including deceleration, by calculating i (Japanese Patent Laid-Open No. 1-12
(See Publication No. 5532, etc.).

That is, the total opening area of the engine intake system is searched and determined from a pre-stored map based on the throttle valve opening TVO, the duty of the idle control valve, etc., and the total opening area AA of the engine intake system obtained is used as the engine. 4f divided by the rotation speed
Based on AA/H, the basic volumetric efficiency QHφ corresponding to AA/N is searched from a map which is also stored in advance. Then, from the obtained basic volumetric efficiency QHφ, the basic fuel injection amount αN is calculated based on the total opening area of the engine intake system.
Tp is determined (αNTp=C−QHφ: C is a coefficient), and transient correction is performed based on the amount of change in αNTp.

Incidentally, in the L Citro, the QHφ is also used to correct the error of the air flow meter.

<Problems to be Solved by the Invention> However, in such a system that performs various corrections using the basic volumetric efficiency QHφ (engine load parameter) obtained from the total opening area of the engine intake system, it is necessary to The value of basic volumetric efficiency QHφ changes due to deterioration due to clogging of various parts such as the throttle valve and idle control valve installed in the engine, which reduces the correction accuracy and makes it difficult for the fuel injection amount to match the engine required amount. It disappears and the emissions worsen.

There was a problem in that problems such as deterioration of engine drivability occurred.

The present invention was made in view of the above circumstances, and it monitors deterioration such as clogging of parts installed in the engine intake system, and
An object of the present invention is to provide an electronically controlled fuel injection device for an internal combustion engine that prevents deterioration of engine operating performance by correcting engine load parameters determined from the opening area of the engine intake system in accordance with the degree of deterioration when the engine deteriorates. shall be.

<Problems to be Solved by the Invention> For this reason, the present invention provides an auxiliary air control valve that bypasses the throttle valve and is duty-controlled with an electromagnetic auxiliary air control valve installed in the engine intake system, as shown in FIG. an engine load parameter calculation means for calculating an engine load parameter based on the opening area of the engine intake system and the engine rotational speed; and a fuel for controlling the fuel injection amount based on the calculation value of the engine load parameter calculation means. In an electronically controlled fuel injection device for an internal combustion engine, the electronically controlled fuel injection device for an internal combustion engine includes an idling operation detecting means, and a duty setting means for setting a duty to the auxiliary air control valve based on an engine operating state detected during idling. a determining means for comparing the actual duty set by the duty setting means with a predetermined duty set in advance and determining that a component installed in the engine intake system has deteriorated when the actual duty is larger than the predetermined duty; and a correction means for correcting the engine load parameter according to the difference between the actual duty and the predetermined duty when the means determines that the component has deteriorated.

<Operation> In this configuration, when the idle operation detecting means detects that the engine is in idle operation, the duty setting means sets the duty of the auxiliary air control valve corresponding to the engine operating state at that time. Deterioration determination is performed by comparing the duty set at this time with a predetermined duty for deterioration determination corresponding to the same operating state, which is set in advance in the determining means. That is, at idle, a target idle engine rotational speed corresponding to the operating state is determined, and the opening/closing degree of the auxiliary air control valve is controlled to supply the required amount of intake air so as to reach this target idle rotational speed. Therefore,
If the parts have deteriorated and become clogged, in order to supply the necessary amount of air, the valve opening must be controlled to a greater extent than when the valve is new and free of blockages.

Therefore, when the actual duty is larger than the predetermined duty, the determining means determines that the component has deteriorated. Then, by correcting the engine load parameter according to the difference in duty at that time by the correction means, and using this corrected value,
Try to optimize control.

<Example> An example of the present invention (in the case of L-JETRO) will be described below based on the drawings.

In FIG. 2, an air cleaner 2 is connected to an engine 1 via a throttle valve 3 linked to an accelerator pedal and an electromagnetic auxiliary air control valve 5 installed in an auxiliary air passage 4 that bypasses the throttle valve 3. Furthermore, intake manifold 6
Air is inhaled through. The opening degree of the auxiliary air control valve 5 is controlled by duty control by a control signal from a control unit 8, which will be described later.

A fuel injection valve 7 is provided in each branch of the intake manifold 6 for each cylinder. The fuel injection valve 7 is an electromagnetic fuel injection valve that opens when a solenoid is energized and then closes when the energization is stopped and is energized by a solenoid. Fuel is injected under pressure and adjusted to a predetermined pressure by a pressure regulator.

Further, an ignition plug 9 is provided in the combustion chamber of the engine 1,
This ignites a spark to ignite and burn the air-fuel mixture. The control unit 8 is a CPU.

Equipped with a microcomputer that includes ROM, RAM, and an A/D converter dual output interface, it performs arithmetic processing based on input signals from various sensors and controls the fuel injection valve 7. Controls the operation of the auxiliary air control valve 5 and the spark plug 9.

As the various sensors mentioned above, a hot wire type air flow meter 10 is provided in the intake passage upstream of the throttle valve 3, and detects an intake air flow of 1 ftQ. In the case of D-JETRO, an intake pressure sensor is provided in the intake manifold to detect intake pressure (intake negative pressure) PB.

Further, a crank angle sensor 11 is provided, and for example, in the case of a four-cylinder engine, a reference signal REF is provided for each crank angle of 180°.
and a unit signal PO8 for each crank angle of 1 to 2 degrees. Here, by measuring the cycle of the reference signal REF or the number of occurrences of the unit signal PO3 within a predetermined time,
The engine rotation speed N can be calculated.

Further, the throttle valve 3 is provided with a throttle sensor 12 that includes a potentiometer that detects the throttle valve opening degree T■0 and an idle switch 12A that is turned on at its fully closed position (idle position).

In addition, the 02 sensor 14 is attached to the exhaust manifold 13 of the engine 1.
is installed to detect whether the air-fuel ratio is rich or lean via the oxygen concentration in the exhaust gas.

Further, a water temperature sensor 15 is provided facing the water jacket of the engine l, and detects the engine cooling water temperature Tw. Furthermore, it is ON when the transmission is in the neutral position.
A neutral switch 16 and a vehicle speed sensor 17 for detecting vehicle speed VSP are provided.

In this embodiment, the functions of duty setting means 3 publishing means 2 engine load parameter calculation means and fuel injection amount control means are provided in the form of software, as shown in the flowchart of FIG.

Next, the fuel injection amount control of this embodiment performed by the control unit will be explained with reference to the flowchart of FIG.

In step 1 (indicated by Sl in the figure, the same applies hereinafter), signals from various sensors are input.

In step 2, it is determined whether or not the vehicle is idling. Here, idling operation means that the idle switch 12A is OFF.
When the neutral switch 16 is turned on, or when the idle switch 12A is turned on, the vehicle speed VSP detected by the vehicle speed sensor 17 is less than or equal to a predetermined value (for example, 8 km/h).

When driving other than idling, skip steps 3 to 8 and proceed to step 9. When driving at idle, skip steps 3 to 8.
Execute.

In step 3, parameters related to the engine operating state,
For example, the duty rscos of the auxiliary air control valve is set to control the engine rotation to a target idle rotation speed set in accordance with the engine cooling water temperature Tw from the water temperature sensor 15.

In addition, the duty to the auxiliary air control valve IS CON (
%) is I S C0N= I S Ctw + I S
It is calculated using the CCL formula. Here, l5Cy+=
is a basic control value, which is set based on the engine cooling water temperature Tw with reference to a map on the ROM. l5CCL is a feedback correction value that is set by comparing the engine rotation speed with the target idle rotation speed and increasing or decreasing it by proportional/integral control based on the comparison result.

In step 4, a duty value ISC for component deterioration determination corresponding to the current engine cooling water temperature Tw detected by the water temperature sensor 15 is retrieved from a map set in advance in the ROM. Here, the setting of the duty value for deterioration determination is higher than the basic control value l5CON at the same engine cooling water temperature Tw.

In step 5, the current duty l5CON obtained in steps 3 and 4 and the deterioration judgment duty 1s are
Compare co. And rsc,.

>l5Co, the auxiliary air control valve 5 is
Since the opening degree of the auxiliary air control valve 5 is controlled to be large, it is determined that the auxiliary air control valve 5 is clogged and has deteriorated, and the process proceeds to step 6.

In step 6, the degree of deterioration B (%) is calculated based on the difference between the actually given control duty l5CON and the set duty ISC.

In step 7, a correction coefficient M for correcting the basic volumetric efficiency QHφ is searched from a map set in advance in the ROM based on the degree of deterioration B calculated in step 6.

Also, in step 5, rsco, ≦ISC.

If it is determined that there is no deterioration, step 6.7
is skipped and the process proceeds to step 8, where the correction coefficient M is set to M=1.

In step 9, a value A is obtained by dividing the opening area AA of the engine intake system by the engine rotational speed N, which is retrieved from a preset map based on the throttle valve opening TVO and l5CON.
Basic volumetric efficiency QH based on the map set in advance from A/N
Search for φ.

In step 10, the corrected basic volumetric efficiency Q'Hφ is calculated by multiplying the basic volumetric efficiency QHφ obtained in step 9 by the correction coefficient M set in step 7 or step 8.

In step 11, various correction values such as transient correction are calculated based on the corrected basic volumetric efficiency Q'Hφ calculated in step 10.

In step 12, the final fuel amount obtained by correcting the basic fuel injection amount Tp obtained from the intake air flow rate Q obtained by the air flow meter IO and the engine rotational speed N based on the correction value calculated in step 11, etc. A pulse output corresponding to the injection amount Ti is generated.

In this way, the degree of clogging of the engine intake system is determined based on the actual air flow rate during idle control, and when the degree of clogging exceeds a certain value, it is determined that the parts of the intake system have deteriorated. In other words, depending on the degree, the basic volumetric efficiency QH
Since φ is corrected, deterioration in engine operating performance due to parts deterioration can be prevented.

When determining the degree of clogging only for the auxiliary air control valve 5, for example, in idle control, a predetermined step change ΔS is added to the basic control value l5CT and the feedback correction value ■5CcL, and the duty l5C is determined.
Set the OS and output.

Then, the determination can be made based on the difference ΔQ between the intake air flow rate values detected by the air flow meters before the step change and after a predetermined time has elapsed after the step change. That is, Δ
If Q is a value approximately equivalent to the step amount ΔS, it is determined to be normal, and if it is less than a predetermined value, it is determined to be degraded.

Then, at the time of deterioration, the degree of deterioration may be determined based on ΔQ and the determination value, and the basic volumetric efficiency QHφ may be corrected according to this degree of deterioration.

<Effects of the Invention> As explained above, according to the present invention, when performing various corrections using engine load parameters for engine load detection obtained based on the opening area of the engine intake system, It is possible to prevent deterioration of engine operating performance due to changes in the opening area of the engine intake system due to deterioration such as clogging of intervening parts,
By correcting according to the degree of deterioration, control can be optimized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the invention, and FIG. 3 is a flowchart showing control details in the above embodiment. l... Engine 3... Throttle valve 4... Auxiliary air passage 5... Auxiliary air control valve 7... Fuel injection valve 8... Control unit 10.
...Air flow meter 11...Crank angle sensor 12...Throttle sensor 12A...Idle switch 15...Water temperature sensor Patent applicant Japan Electronics Co., Ltd.

Claims (1)

[Claims] The engine intake system is equipped with an auxiliary air passage that bypasses the throttle valve and is equipped with an electromagnetic auxiliary air control valve whose duty is controlled. In an electronically controlled fuel injection device for an internal combustion engine, the electronically controlled fuel injection device for an internal combustion engine includes an engine load parameter calculation means for calculating, and a fuel injection amount control means for controlling the fuel injection amount based on the calculated value of the engine load parameter calculation means, the idle operation detection means; , a duty setting means for setting a duty to the auxiliary air control valve based on the engine operating state detected during idling, and a duty setting means for comparing the actual duty set by the duty setting means with a predetermined duty set in advance to determine the actual duty. determining means for determining that a component installed in the engine intake system has deteriorated when the duty is greater than a predetermined duty; and determining means for determining that a component installed in the engine intake system has deteriorated when the duty is greater than a predetermined duty; An electronically controlled fuel injection device for an internal combustion engine, comprising a correction means for correcting a load parameter.