JPH07229459A - Intake air control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To appropriately control air-fuel ratio so as to insure favorable operability and exhaust emission property by setting a fuel increasing quantity correcting factor matching with a supply quantity of assist air, when the atmospheric pressure is lowered at altitude running or the like. CONSTITUTION:A control unit 12 controls an idle control valve 14 by feedback at idle operation so that the engine speed approaches a target idle engine speed. A solenoid valve 16 in an assist air passage 15 provided so as to bypass a throttle valve 4 is controlled, air (assist air) led by pressure difference across the throttle valve 4 is jetted in the vicinity of the nozzle of a fuel injection valve 6, and hence atomization of injected fuel is promoted. In this case, using weight searched according to the atmospheric pressure, a fuel increasing quantity correcting factor is set by a weight average of a reference value for non-supply of assist air and a reference value for supply of assist air. Hereby the assist air supply territory is enlarged so as to dissolve shortage of assist air flow at idling.

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, an electromagnetically driven fuel injection valve is provided,
In an internal combustion engine equipped with an electronically controlled fuel injection device that automatically controls the fuel injection amount according to the engine operating state, when the engine temperature is low, part of the intake air is injected as assist air from the intake passage upstream of the throttle valve. It is known that the fuel is atomized by guiding it near the injection hole of the valve and colliding the fuel injected from the fuel injection valve with the assist air, thereby improving combustion and improving fuel economy and exhaust properties. (Japanese Patent Publication No. 64-9465, Japanese Utility Model Publication No. 63-18)
767, etc.).

On the other hand, in the electronically controlled fuel injection device, the fuel injection amount is increased according to the engine speed N and the load of the engine, for example, the basic fuel injection amount T _P , in order to increase the engine output under a predetermined high load operating condition. Increasing correction is generally performed. However, in the case where the assist supply device is additionally provided, when the assist air is supplied, the amount of fuel injected from the fuel injection valve is reduced by the assist air and the mixture ratio is diluted. It is desirable to further strengthen the injection amount increase. Therefore, there is a system in which the amount increase correction is performed by using different mixture ratio correction coefficients when the assist air is supplied and when the non-assist air is supplied.

[0004]

However, if different mixing ratio correction coefficients are used as described above,
The following problems occurred. 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, if the fuel injection amount increase correction is performed using the increase correction coefficient set on the basis of the low land having the standard atmospheric pressure at the time of supplying the assist air in the high altitude, the fuel injection amount is excessively corrected and the drivability is deteriorated ( Occurrence of hesitation shock). The present invention has been made in view of such conventional problems, and intake control of an internal combustion engine that solves the above problems by performing assist air supply while restricting fuel increase correction under conditions of low atmospheric pressure. The purpose is to provide a device.

[0006]

Therefore, the first intake control system for an internal combustion engine according to the present invention, as shown in FIG. 1, uses the differential pressure between the atmospheric pressure and the negative intake pressure of the engine to control the fuel injection valve. An intake air control device for an internal combustion engine, comprising: an assist air passage for guiding assist air to the vicinity of an injection hole; and an assist air control means for controlling an opening of the assist air passage to control supply of assist air. An atmospheric pressure detecting means for detecting the atmospheric pressure, and an atmospheric pressure detected by the atmospheric pressure detecting means for the correction coefficient for increasing and correcting the fuel supply amount from the fuel injection valve under a predetermined operating condition, and the assist air control means. And a correction coefficient setting means for setting the assist air according to the supply state of the assist air.

Here, the assist air control means controls the supply / interruption of assist air by switching the assist air passage between fully open and fully closed, and the correction coefficient setting means includes the assist air setting means. It is also possible to adopt a configuration in which two types of basic correction coefficients set according to air supply / interruption are weighted and averaged by weighting set based on the detected atmospheric pressure.

Further, the assist air control means continuously controls the opening degree of the assist air passage from fully closed to fully open, and the correction coefficient setting means comprises:
The basic value may be corrected and set with a correction coefficient set according to the opening degree of the assist air passage and a correction coefficient set based on the detected atmospheric pressure.

Further, in the second intake control device for an internal combustion engine according to the present invention, as shown by the solid line in FIG. 2, a differential pressure between the atmospheric pressure and the intake negative pressure of the engine causes a difference in the vicinity of the injection hole of the fuel injection valve. An assist air passage for guiding the assist air, an assist air control means for opening the assist air passage to supply the assist air under a low temperature condition of the engine, and an auxiliary air flow rate control for controlling an air flow amount for assisting bypass of the throttle valve at idle. In the intake control device for an internal combustion engine, the means for detecting the atmospheric pressure, and an engine temperature for supplying the assist air when the atmospheric pressure is low according to the detected atmospheric pressure. The upper limit temperature switching means for increasing the upper limit value of is included.

In this device, as indicated by a dotted line in FIG. 2, a correction coefficient for increasing and correcting the fuel supply amount from the fuel injection valve under a predetermined operating condition is the atmospheric pressure detected by the atmospheric pressure detecting means and the It may be configured to include a correction coefficient setting unit that is set according to the supply state of the assist air by the assist air control unit.

[0011]

When the amount of assist air supplied by the assist air control means is increased, or when the assist air supply is switched from none to on, the fuel increase correction coefficient is set to be large in proportion to the amount of increase in the amount of assist air. Is required. On the other hand, when the atmospheric pressure falls below a predetermined level due to traveling at high altitudes, etc., the differential pressure from the intake pressure becomes smaller,
The amount of assist air supplied under the same load (intake pressure) condition as compared to when traveling at low altitude is reduced even if the opening degree of the assist air passage by the assist air control means is the same.

Therefore, by setting the fuel increase correction coefficient in accordance with the assist air supply state (opening of the assist air passage) and the atmospheric pressure by the assist air control means, the true assist air supply amount is met. It is possible to correct the fuel amount increase, and it is possible to maintain the operating performance and exhaust emission performance by controlling the optimum mixing ratio while supplying the assist air even when traveling at high altitudes.

By the way, the assist air supply is switched between fully open and fully closed to control the supply / interruption of the assist air. Two types of fuel increase preset according to the supply / interruption of the assist air are provided. There is one that uses the correction coefficient by switching. Therefore, the present invention is applied to those that perform this type of control, and when the assist air is supplied, the above two types of correction coefficients are used as basic correction coefficients, and weighted averaging processing is performed with weighting set based on the detected atmospheric pressure. With this configuration, the atmospheric pressure can be corrected by a simple calculation, and the performance according to the present invention can be obtained.

On the other hand, in the case where the opening of the assist air passage is continuously variably controlled, it is preferable that the fuel increase correction is also continuously changed according to the change of the opening of the passage, and at the same time, even if the atmospheric pressure changes. It is preferable to change continuously. Therefore, when the present invention is applied to those that perform this type of control, the reference opening degree of the assist air passage,
The basic value of the fuel increase correction coefficient set for atmospheric pressure is corrected by the correction coefficient set according to the opening degree of the assist air passage and the correction coefficient set based on the detected atmospheric pressure. With this setting, it is possible to perform extremely fine fuel increase correction, and to further improve the performance according to the present invention.

Further, a device for controlling the idle rotation speed by controlling the auxiliary air flow amount that bypasses the throttle valve at the time of idling is generally provided, but at the time of traveling at high altitude, the auxiliary air flow amount is sufficiently secured by lowering the air density. Difficult to do. Therefore, under low atmospheric pressure conditions, by increasing the upper limit of the engine temperature to supply the assist air, the temperature range for supplying the assist air is expanded to secure the intake air flow rate during idling and at the same time atomize the fuel. It is possible to promote and secure good idle drivability.

Further, in this device as well, similar to the first intake device, by adding a configuration for correcting the fuel increase correction coefficient according to the atmospheric pressure and the assist air supply state, the mixture ratio is optimally controlled. can do.

[0017]

EXAMPLES Examples of the present invention will be described below. In FIG. 3 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.

Further, a water temperature sensor 10 for detecting the cooling water temperature Tw of the water jacket of the engine 1 is 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 on the basis of 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 corrected. 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 for controlling the opening / closing of the assist air passage 15 on / off. 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. The opening / closing control of the solenoid valve 16 by the control unit 12 and the fuel correction switching control associated therewith will be described below with reference to the flowchart of FIG.

In the flow chart of FIG. 4, 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 P detected by the atmospheric pressure sensor 21 are read. In step 2, the upper limit value T _W OFF of the engine cooling water temperature at which the assist air supply is stopped according to the detected atmospheric pressure P is searched for from a preset map. Here, the lower the atmospheric pressure P, the higher the upper limit value T _W OFF is set.
As a result, as the atmospheric pressure P decreases, the maximum flow rate of the auxiliary air by the idle control valve 14 decreases, and the assist air is supplied to compensate for the decrease, so that the required intake air flow rate is reduced. It is possible to secure the idle performance.

In step 3, the detected cooling water temperature Tw is compared with the T _W OFF. And T _W <
If T _W OFF, the routine proceeds to step 4, where the solenoid valve 16 is opened to supply the assist air. In step 5, the fuel injection amount increase correction coefficient K, which will be described later, according to the atmospheric pressure P.
The weight A when setting the MR is searched from a preset map. Here, the weight A is set to have a smaller value as the atmospheric pressure P is higher.

In step 6, the increase correction coefficient KMR is calculated according to the following equation. The function of step 6 corresponds to the correction coefficient setting means. KMR = {KMRON + (A-
1) ・ KMROFF} / A where KMRON is the increase correction coefficient set according to the time of supplying assist air, KMR
OFF is an increase correction coefficient that is set according to when the assist air is not supplied. Since the intake air is increased by the assist air when the assist air is supplied, KMRON> KMRO
It is set to FF. The weight A is set as a weight for KMROFF, and is set to a smaller value as the atmospheric pressure P is higher as described above. Therefore, when the atmospheric pressure is high, the increase correction coefficient set accordingly is set. The weight of KMRON is large, the increase correction coefficient KMR is set to a relatively large value, and as the atmospheric pressure decreases, the increase correction coefficient KMROF when the assist air is not supplied
By increasing the weight of F, the increase correction coefficient KM
R is set by reducing and modifying.

That is, as the atmospheric pressure is low and the assist air supply amount is decreased, the increase correction coefficient KMR is also decreased and set, so that the mixing ratio can be set in accordance with the assist air supply amount, and the high altitude can be set. Good drivability is ensured even during driving, and exhaust emission performance is also improved. If it is determined in step 3 that T _W ≧ T _W OFF, the process proceeds to step 7, the solenoid valve 16 is closed to stop the supply of assist air, and the process proceeds to step 8 to assist the fuel increase correction coefficient KMR. A relatively small KMROFF for stopping the air supply is used.

The above is applied to the one in which the solenoid valve 16 is switched between fully closed and fully opened, but is also applied to the one in which the opening degree of the solenoid valve 16 is variably controlled and the assist air supply amount is variably controlled. it can. Increase correction coefficient KMR in this embodiment
The setting routine is shown in the flowchart of FIG. Step 11 to step 13 and step 17 and step 18 are similar to step 1 to step 3 and step 7 and step 8 of FIG.

In step 14, the opening degree V _A of the solenoid valve 16 is set according to the engine operating conditions such as the engine rotation speed and the engine load. In step 15, it controls the opening degree V _A outputs a driving signal of the opening V _A to the solenoid valve 16, in step 16,
Based on the opening degree V _A of the solenoid valve 16 and the atmospheric pressure P, the fuel increase correction coefficient KMR is retrieved from a preset three-dimensional map. That is, the mass flow rate of the assist air is estimated from the opening degree V _A of the solenoid valve 16 and the atmospheric pressure P, and the increase correction coefficient KMR corresponding to it is set. Therefore, also in this embodiment, the idle performance during high altitude traveling can be ensured, and the mixing ratio is controlled to match the assist air supply amount, so that the drivability and exhaust emission performance during high altitude traveling can be obtained.

[0033]

As described above, according to the present invention, when the atmospheric pressure is lowered, for example, when traveling at high altitudes, the fuel increase correction coefficient corresponding to the assist air supply amount is set so that the mixture ratio becomes appropriate. Can be controlled to ensure good drivability and exhaust emission.

Further, by expanding the temperature range in which the assist air is supplied in the case of controlling the auxiliary air flow rate during idling, the decrease in the auxiliary air flow rate due to the decrease in atmospheric pressure can be compensated by the supply of the assist air, Idle performance at high altitudes can be secured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration / function according to a first aspect of the present invention.

FIG. 2 is a block diagram showing a configuration / function according to a second aspect of the invention.

FIG. 3 is a system schematic diagram showing an embodiment of the present invention.

FIG. 4 is a flowchart showing a routine for setting assist air supply and a fuel increase correction coefficient according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a routine for setting assist air supply and a fuel increase correction coefficient according to a second embodiment of the present invention.

[Explanation of symbols]

 1 engine 6 fuel injection valve 12 control unit 14 idle control valve 15 assist air passage 16 solenoid valve 22 atmospheric pressure sensor

Claims (5)

[Claims] 1. An assist air passage for guiding 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 an assist air supply by controlling an opening of the assist air passage. In an intake air control device for an internal combustion engine, which includes an assist air control unit for controlling the air pressure, an atmospheric pressure detection unit for detecting an atmospheric pressure, and a fuel supply amount from the fuel injection valve are increased under a predetermined operating condition. And a correction coefficient setting means for setting a correction coefficient to be corrected according to the atmospheric pressure detected by the atmospheric pressure detecting means and the supply state of the assist air by the assist air control means. Intake control device for internal combustion engine. 2. The assist air control means controls the supply / interruption of assist air by switching the assist air passage between fully open and fully closed, and the correction coefficient setting means comprises the assist air setting means. 2. The internal combustion engine according to claim 1, wherein the two types of basic correction coefficients set in accordance with the supply / shutoff of the internal combustion engine are weighted and averaged by weighting set based on the detected atmospheric pressure. Intake control device for the engine. 3. The assist air control means continuously controls the opening degree of the assist air passage from fully closed to fully open, and the correction coefficient setting means sets a basic value to the assist air control means. The intake control of the internal combustion engine according to claim 1, wherein the correction coefficient is set according to the opening degree of the passage and the correction coefficient is set based on the detected atmospheric pressure. apparatus. 4. An assist air passage for guiding assist air to the vicinity of an injection hole of a fuel injection valve by a pressure difference between an atmospheric pressure and an intake negative pressure of the engine, and the assist air passage is opened under low temperature conditions of the engine to provide the assist air. In an intake air control device for an internal combustion engine, which is configured to include an assist air control means for supplying and an auxiliary air flow rate control means for controlling an auxiliary air flow rate for bypassing a throttle valve at the time of idling, atmospheric pressure detection for detecting atmospheric pressure Means and an upper limit temperature switching means for raising the upper limit value of the engine temperature for supplying the assist air when the atmospheric pressure is low according to the detected atmospheric pressure. apparatus. 5. A correction coefficient for increasing and correcting the fuel supply amount from the fuel injection valve under a predetermined operating condition is an atmospheric pressure detected by the atmospheric pressure detection means and a supply state of assist air by the assist air control means. An intake control device for an internal combustion engine, comprising: a correction coefficient setting means which is set according to the above.