JPH07189833A - Intake controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent deterioration of operativity such as a hesitation shock due to overcorrection by regulating supply of assist air when an atmospheric pressure is reduced in highland traveling or the like and (W carrying out following regulation for increase in fuel quantity. CONSTITUTION:A cooling water temperature Tw detected by a water temperature sensor 10 and an atmospheric pressure A detected by an atmospheric pressure sensor 21 are read, and the cooling water temperature Tw is compared with the predetermined value Tw0 set at a low temperature. When Tw is not less than Tw0, a solenoid valve 16 is tumed off, and a mixture ratio correction factor for a steady time and a fuel increase correction factor for a transient time during a cutoff of assist air supply are selected. When Tw is less than Tw0, the atmospheric pressure A is compared with the predetermined value A0, and if A is not less than A0, the solenoid valve 16 is turned on, so that a mixture ratio correction factor for a steady time and a fuel increase correction factor for a transient time during assist air supply are selected. In this way, supply of assist air is cut off at a low atmospheric pressure when the atmospheric pressure is not more than predetenoined value, and fuel increase correction is stopped, so that deterioration in operativity is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air control device provided with an assist air supply device for an internal combustion engine, and more particularly, it has taken measures against adverse effects caused by a reduction in atomization function due to assist air when the air density is lowered at high altitudes. Regarding technology.

[0002]

2. Description of the Related Art Conventionally, as an assist air supply device for an internal combustion engine, a part of intake air is guided as assist air from an intake passage upstream of a throttle valve to the vicinity of an injection hole of a fuel injection valve, and the intake air is supplied from the fuel injection valve. It is known that the assisted air collides with the injected fuel to atomize the fuel, thereby improving combustion and improving fuel efficiency and exhaust gas properties (Japanese Patent Publication No. 9465/1989). Kosho 6
3-18767, etc.).

By the way, when assist air is supplied, the intake negative pressure in the vicinity of the injection hole of the fuel injection valve rises steadily, so that the differential pressure from the atmospheric pressure decreases, and the fuel injection amount set to the same, The fuel injection amount decreases with respect to the opening time of the fuel injection valve (see Fig. 4), and transiently the assist air expands the spray angle to increase the so-called wall flow rate. Supply decreases (Fig. 5
See).

Therefore, in some cases, when the assist air is supplied, an increase correction for the steady and transient decrease in the fuel injection amount is performed compared to when the assist air is not supplied.

[0005]

However, the following problems occur in the case where the increase correction of the fuel injection amount is performed at the time of supplying the assist air as described above. That is, when the atmospheric pressure decreases and the air density decreases when traveling at high altitudes, the flow rate of assist air decreases under the same operating conditions (engine speed, load). This is because even under the same operating condition where the intake negative pressure is the same, the atmospheric pressure decreases, and therefore the differential pressure between the atmospheric pressure supplying the assist air and the intake negative pressure decreases.

As a result, when the correction amount for increasing the fuel injection amount in response to the assist air supply is performed in the highland as in the case of the lowland, the overcorrection results in deterioration of drivability (occurrence of hesitation shock). Further, since the assist air flow rate itself is reduced and the atomization effect of the fuel is weakened, the above tendency is further promoted.

The present invention has been made in view of the above conventional problems. In the intake of an internal combustion engine, which solves the above problems, the supply of the assist air and the correction of the fuel increase amount are restricted under the condition of low atmospheric pressure. An object is to provide a control device.

[0008]

Therefore, the present invention is based on FIG.
As shown in, an assist air passage for supplying assist air to the vicinity of the injection hole of the fuel injection valve by a pressure difference between the atmospheric pressure and the intake negative pressure of the engine, and a passage opening control for controlling the opening of the assist air passage. In an intake control device for an internal combustion engine, the intake control device detects the atmospheric pressure, and a fuel supply amount correction unit that corrects the fuel supply amount to the engine according to the opening degree of the assist air passage. And an opening control means for restricting the opening of the assist air passage to a minimum when the atmospheric pressure is a low pressure equal to or lower than a predetermined level.

[0009]

[Function] When the atmospheric pressure drops below a predetermined level during high-altitude driving, the opening of the assist air passage is minimized (including fully closed).
Regulated by. As a result, the assist air flow rate is minimized (0
(Including 0) and the increase correction of the fuel supply amount decreases according to the minimum opening of the assist air passage (including 0)
Therefore, deterioration of drivability such as hesitation due to overcorrection can be prevented.

[0010]

EXAMPLES Examples of the present invention will be described below. In FIG. 2 showing an embodiment, air is drawn into an internal combustion engine 1 from an air cleaner 2 through an intake duct 3, a throttle valve 4 and an intake manifold 5. At each branch portion of the intake manifold 5, a fuel injection valve 6 is provided for each cylinder.

The fuel injection valve 6 is an electromagnetic fuel injection valve which is energized by a solenoid to open the valve, and deenergized to close the valve. A drive pulse signal having a predetermined pulse width is sent from a control unit 12 described later. Thus, the fuel is intermittently driven to open, and is fed under pressure from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator to be injected and supplied to the engine 1. The fuel injection valve 6 is installed so as to face the intake valve.

A spark plug 7 is provided in each combustion chamber of the engine 1, and spark ignition is performed by the spark plug 7 to ignite and burn the air-fuel mixture. Exhaust gas from the engine 1 is discharged through an exhaust manifold 17, an exhaust duct 18, a catalyst 19, and a muffler 20. The control unit 12 includes a CPU, ROM, RAM, A /
A microcomputer including a D converter, an input / output interface, and the like is provided, which receives input signals from various sensors and controls the pulse width of the drive pulse signal given to the fuel injection valve 6, while the engine load. ， Set ignition timing ADV according to engine operating conditions such as engine speed,
Ignition by the spark plug 7 is controlled.

As the various sensors, the intake duct 3 is used.
An air flow meter 8 is provided therein and outputs a signal according to the intake air flow rate Q of the engine 1. Further, a crank angle sensor 9 is provided, and a reference angle signal REF for each predetermined piston position (for example, BTDC70 ° CA) in each cylinder and a unit angle signal P for each crank angle 1 ° or 2 °.
Output OS and respectively. Here, the engine rotation speed Ne can be calculated by measuring the cycle of the reference angle signal REF or the number of generated unit angle signals POS within a predetermined time.

A water temperature sensor 10 for detecting the cooling water temperature Tw of the water jacket of the engine 1 is also provided.
Further, a throttle sensor 11 for detecting the opening degree TVO of the throttle valve 4 by a potentiometer is provided. In addition, an oxygen sensor 21 that detects the oxygen concentration in the exhaust gas is provided at the collecting portion of the exhaust manifold 17.
The oxygen sensor 21 is a known sensor that detects rich / lean with respect to the stoichiometric air-fuel ratio by detecting the oxygen concentration in the exhaust gas that is closely related to the air-fuel ratio of the engine intake air-fuel mixture.

Then, the control unit 12 performs proportional / integral control of the air-fuel ratio feedback correction coefficient α based on the rich / lean of the actual air-fuel ratio with respect to the stoichiometric air-fuel ratio detected by the oxygen sensor 21, and the air-fuel ratio is controlled. It has an air-fuel ratio feedback control function of performing feedback control to the theoretical air-fuel ratio which is the target air-fuel ratio by correcting the basic fuel injection amount with the feedback correction coefficient α.

On the other hand, an electromagnetic idle control valve 14 is provided in a bypass passage 13 provided by bypassing the throttle valve 4. The idle control valve 14 is an opening adjustment valve whose opening is adjusted by duty-controlling the energization of an attached electromagnetic coil, and the control unit 12 having a function as idle rotation control means.
Is the engine speed Ne in a predetermined idle operation state.
So as to approach the target idle speed, the duty ratio DU of the energizing pulse signal output to the idle control valve 14
TY (control value) is feedback-controlled.

Further, an assist air passage 15 is provided which branches from the intake duct 3 on the upstream side of the throttle valve 4 and bypasses the throttle valve 4 and opens near the injection hole of each fuel injection valve 6. The air (hereinafter referred to as assist air) guided by the pressure difference between the upstream and downstream sides of No. 4 is ejected near the injection hole of the fuel injection valve 6 and collides with the injected fuel to promote atomization of the injected fuel. ing.

In the middle of the assist air passage 15, there is provided a normally closed solenoid valve 16 that controls the opening and closing of the assist air passage 15. This solenoid valve 16 as a passage opening control means is basically on / off controlled by the control unit 12 on the basis of information such as the cooling water temperature Tw detected by the water temperature sensor 10. An atmospheric pressure sensor 22 for detecting the atmospheric pressure is provided as a configuration according to the present invention, and the solenoid valve 16 is controlled to be turned on / off in accordance with the atmospheric pressure detected by the atmospheric pressure sensor 22. The supply / cutoff of the assist air ejected to the nozzle hole as a part of the engine intake air is controlled by switching.

The control unit 12 controls the supply / cutoff of the assist air by the on / off control of the solenoid valve 16 as described above, and increases the fuel amount in response to the supply / cutoff of the assist air, that is, the opening / closing of the assist air passage. Controls the presence / absence of correction. Below, the opening / closing control of the solenoid valve 16 by the control unit 12 and the switching control of the fuel correction associated therewith will be described with reference to the flowchart of FIG.

In the flowchart of FIG. 3, first, in step 1 (denoted as S1 in the figure, the same applies hereinafter)
The cooling water temperature Tw detected by the water temperature sensor 10 and the atmospheric pressure A detected by the atmospheric pressure sensor 21 are read. In step 2, the cooling water temperature Tw is set to a predetermined value T set to a low temperature.
Compare with w ₀ .

When it is determined in step 2 that Tw ≧ Tw _0, it is determined that it is not necessary to supply the assist air, and the process proceeds to step 3 and subsequent steps. In step 3, the solenoid valve 16 is turned off, in step 4, the mixing ratio correction coefficient KMR _C for steady state when the assist air supply is cut off is selected, and in step 5, the fuel for transient state when the assist air supply is cut off is also selected. Select the increase correction coefficient KACC _C.

When it is determined that Tw <Tw _{0 in} step 2, it is determined that the cooling water temperature Tw is low and the condition of assist air supply is satisfied, and step 6
Proceed to the following. In step 6, the atmospheric pressure A is set to a predetermined value A
Compare with ₀ . When A ≧ A _0, it is determined that the pressure difference between the atmospheric pressure and the intake negative pressure is sufficiently large, and a sufficient assist air flow rate can be secured, and the routine proceeds to step 7 and subsequent steps.

In step 7, the solenoid valve 16 is turned on, in step 8, the mixing ratio correction coefficient KMR _O for steady state during assist air supply is selected, and in step 9, the fuel for transient state during assist air supply is also selected. Select the increase correction coefficient KACC _O. The steady state mixture ratio correction coefficient KMR _O and the transient fuel amount increase correction coefficient KACC _O when the assist air is supplied are respectively the steady state mixture ratio correction coefficient KM _RC and Compared to the fuel increase correction coefficient KACC _C for transient time, the same operating conditions (engine speed Ne, load, for example, basic fuel injection pulse width T _P )
The value in is set to a large value. That is, as described above, when the assist air is supplied, the fuel injection amount decreases steadily as the differential pressure decreases, and the cylinder intake fuel amount decreases transiently as the wall flow rate increases. From
In order to compensate for this, the value of each correction coefficient for increasing the fuel is set to be larger than the value when the supply of the assist air is cut off. In this way, the function of performing the fuel amount increase correction using the correction coefficient value set to a larger value when the assist air supply is cut off than when the assist air supply is cut off corresponds to the fuel supply amount correction means.

According to the present invention, when the atmospheric pressure is lower than a predetermined pressure, the supply of assist air, which is less effective, is cut off, and the fuel amount increase correction is also stopped accordingly. Can be prevented from worsening. In the present embodiment, the solenoid valve 16 is an on-off valve that switches the assist air passage 10 between full open and full close, but an opening control valve whose opening changes linearly may be used, or it may be completely opened. Even if it has the minimum opening that does not shut off,
When the atmospheric pressure is lower than a predetermined value, the opening of the solenoid valve may be kept to a minimum, and the fuel amount may be reduced accordingly.

[0025]

As described above, according to the present invention, when the atmospheric pressure is lowered during traveling at high altitude, the assist air supply is regulated and the fuel increase is regulated accordingly. It is possible to prevent deterioration of drivability such as shock.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention.

FIG. 2 is a system schematic diagram showing an embodiment of the present invention.

FIG. 3 is a flowchart showing assist air and fuel correction control of the above embodiment.

FIG. 4 is a diagram showing a steady decrease in fuel supply amount due to assist air supply.

FIG. 5 is a diagram showing a transient decrease in fuel supply amount due to assist air supply.

[Explanation of symbols]

 1 engine 6 fuel injection valve 12 control unit 15 assist air passage 16 solenoid valve 22 atmospheric pressure sensor

Claims (1)

[Claims] 1. An assist air passage for supplying assist air to the vicinity of an injection hole of a fuel injection valve by a differential pressure between an atmospheric pressure and an intake negative pressure of an engine, and a passage opening control for controlling an opening of the assist air passage. In an intake control device for an internal combustion engine, the intake control device detects the atmospheric pressure, and a fuel supply amount correction device that corrects the fuel supply amount to the engine according to the opening degree of the assist air passage. And an opening control means for controlling the opening of the assist air passage to a minimum when the atmospheric pressure is lower than a predetermined level. apparatus.