JPH10122028A - Diesel engine controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the calibration accuracy of an air flow meter by setting an air flow meter output calibration rotational speed range which has little influence upon volumetric efficiency by a change in the flow coefficient of an intake passage, and calibrating intake air amount based on a difference between the output of an air flow meter detected in the above range and its basic output. SOLUTION: Where intake air amount is calibrated based on a difference between the output of an air flow meter 29 and preset basic output V0 in a control unit 18, an air flow meter output calibration rotational speed range is first set, which has little influence upon volumetric efficiency determined by constitution of the intake and exhaust system of an engine 1 by a change in the flow coefficient of an intake passage 2. Next, intake air is calibrated based on a difference between the output of the air flow meter 29 detected in the rotational speed range and the basic output V0. Even if the volumetric coefficient of the intake passage 2 is changed by deposits or the like for the cross-section of the passage, the output of the air flow meter 29 hardly changes, therefore, it is possible to correct intake air amount with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a control device for a diesel engine.

[0002]

2. Description of the Related Art Some diesel engines have an air flow meter for detecting an intake air amount, and control a fuel injection amount, a fuel injection timing, an EGR rate, and the like according to the intake air amount.

A conventional apparatus of this type is disclosed in, for example, JP-A-59-74336.

[0004]

The accuracy of detecting the amount of intake air by an air flow meter is such that the initial variation width at the time of manufacturing is in the range of about ± 3%, and the variation width due to aging can be increased to 6%. There is.

Therefore, it is conceivable to calibrate the intake air amount Q based on an output difference ΔVa between the output Va of the air flow meter detected under predetermined operating conditions and a preset basic output V0.

However, when the flow coefficient Cv of the intake passage changes due to deposits or the like on the passage wall surface of the intake passage, the actual intake air amount Q does not match the expected basic intake air amount Q0, and the intake air amount Q is reduced. There is a problem that calibration cannot be performed with sufficient accuracy.

The present invention has been made in view of the above problems, and has as its object to increase the accuracy of calibrating the output of an air flow meter in a diesel engine control device.

[0008]

According to a first aspect of the present invention, there is provided a diesel engine control apparatus including an air flow meter for detecting an intake air amount, wherein a change in a flow coefficient Cv of an intake passage is a volumetric efficiency. An airflow meter output calibration rotation speed region having a small effect on ηv is set, and suction is performed based on an output difference ΔVa between the airflow meter output Va detected in the airflow meter output calibration rotation speed region and a preset basic output V0. Air volume Q
Calibrate.

According to a second aspect of the present invention, there is provided a diesel engine control device, wherein the air flow meter output calibration rotation speed region is set to one.
The rotation speed is set to 500 rpm or less.

According to a third aspect of the present invention, there is provided a diesel engine control device according to the first or second aspect of the present invention, which determines whether the engine is decelerating, and detects the deceleration and in an airflow meter output calibration rotation speed region. The intake air amount Q is calibrated based on the output Va of the air flow meter.

According to a fourth aspect of the present invention, there is provided a diesel engine control apparatus according to any one of the first to third aspects, wherein a plurality of intake air are introduced so as to generate an intake swirl flow in one cylinder. A swirl control means is provided which has an intake port and makes the intake speed distribution at each intake port variable.

According to a fifth aspect of the present invention, there is provided a diesel engine control device according to the fourth aspect, further comprising a tangential port for introducing intake air to one cylinder and a helical port, and the helical port being provided with intake swirl for the cylinder. A swirl control valve which is formed in a spiral shape toward the combustion chamber so as to occur and opens and closes a tangential port according to operating conditions is provided as the swirl control means.

According to a sixth aspect of the present invention, there is provided a diesel engine control device according to any one of the first to fifth aspects, further comprising a heating resistor interposed in an intake passage as the air flow meter. The resistance value of the heating resistor to be heated by the above is changed in accordance with the amount of intake air.

[0014]

In the control apparatus for a diesel engine according to claim 1, an output V of the air flow meter detected in an air flow meter output calibration rotation speed region.
The intake air amount Q is calibrated on the basis of the output difference ΔVa between “a” and the preset basic output V0.

Even if the flow coefficient Cv of the intake passage changes due to deposits or the like with respect to the passage sectional area, the output Va of the air flow meter detected in the air flow meter output calibration rotation speed region hardly changes. Can be calibrated with high accuracy.

As a result, the fuel injection amount and the EGR amount of the diesel engine can be precisely controlled without being affected by the variation in the output characteristics of the air flow meter, and the exhaust performance of the diesel engine can be prevented from deteriorating. , Output performance can be maintained.

FIG. 5 shows a characteristic that the volume efficiency ηv changes with respect to the engine speed in the diesel engine control device according to the second aspect. From now on, about 15
In the rotational speed range of 00 rpm or more, the volume efficiency ηv decreases because the flow coefficient Cv of the intake passage decreases as the swirl control valve closes. The effect of the change in the flow coefficient Cv of the intake passage upon opening and closing of the swirl control valve on the volumetric efficiency ηv increases as the rotational speed increases.

In the rotation speed range lower than approximately 1500 rpm,
Since the dynamic effect of the intake offsets the decrease in the flow coefficient Cv of the intake passage with the closing of the swirl control valve,
Volumetric efficiency ηv even when swirl control valve is closed
Hardly changes.

Therefore, by setting the air flow meter output calibration rotation speed region to a rotation speed region of 1500 rpm or less, a change in the flow coefficient Cv of the intake passage affects the volume efficiency ηv determined by the configuration of the intake / exhaust system. The influence is small, and the intake air amount Q can be accurately corrected based on the output Va of the air flow meter in the air flow meter output calibration rotation speed region.

In the control apparatus for a diesel engine according to the third aspect, the output difference ΔVa between the air flow meter output Va detected during deceleration and in the air flow meter output calibration rotation speed region and a preset basic output V0 is calculated. In order to calibrate the intake air amount Q on the basis of
Can be calibrated with high accuracy even if changes due to deposits or the like with respect to the passage cross-sectional area.

According to a fourth aspect of the present invention, the power of the intake swirling flow generated in the cylinder is adjusted by changing the distribution of the intake speed at the intake port.

Also in this case, the intake air amount Q is calibrated based on the output Va of the air flow meter detected in the air flow meter output calibration rotation speed region.
Can be calibrated with high accuracy.

In the control apparatus for a diesel engine according to the fifth aspect, the flow coefficient Cv of the helical port is liable to change due to deposits on the wall surface, but the output Va of the air flow meter detected in the air flow meter output calibration rotation speed region. By calibrating the intake air amount Q based on
The intake air amount Q can be calibrated with high accuracy.

In the control apparatus for a diesel engine according to the present invention, an output difference between an output Va of an air flow meter comprising a heating resistor detected in an air flow meter output calibration rotation speed region and a preset basic output V0. Since the intake air amount Q is calibrated based on ΔVa, the intake air amount Q can be calibrated with high accuracy even if the flow coefficient Cv of the intake passage changes due to deposits or the like with respect to the passage sectional area.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is a diesel engine main body, 2 is an intake passage, 3 is an exhaust passage, and 5, 6 are intake passages 2.
And an exhaust passage 3 for recirculating a part of the exhaust gas (EGR gas). Reference numeral 7 denotes an EG for opening and closing the EGR passages 5 and 6.
This is an R valve.

The EGR valve 7 is interlocked with the diaphragm type actuator, and is connected to the vacuum pump 8 from the negative pressure passage 1.
1. It operates according to the negative pressure guided through the solenoid valve 12 and the negative pressure passage 15.

A throttle valve 9 is provided upstream of the collector 25 in the intake passage 2. The throttle valve 9 is interlocked with the diaphragm type actuator 10, and the vacuum pump 8
It operates according to a negative pressure guided from the negative pressure passage 11, the electromagnetic valve 13, and the negative pressure passage 14.

The control unit 18 receives the detected values Ne and Acc of the engine speed sensor 17 and the accelerator opening sensor 16 and obtains a target EGR rate from the detected values Ne and Acc based on a map. The control unit 18 inputs a detection value Q of the air flow meter 29 for detecting the intake air amount, obtains an actual EGR rate based on the detection value Q, and controls the EGR rate so that the actual EGR rate approaches the target EGR rate. The amounts of EGR recirculated to the intake passage 3 are feedback-controlled by adjusting the opening degrees of the valve 7 and the throttle valve 9.

In FIG. 1, reference numeral 4 denotes a fuel injection pump. The fuel injection pump 4 pumps high-pressure fuel to injectors (not shown) facing each cylinder, and injects fuel from each injector at a predetermined timing. Control unit 1
8 are the detected values Ne, Ac of the engine speed sensor 17, the accelerator opening sensor 16 and the air flow meter 29.
The fuel injection amount and fuel injection timing from each injector are controlled according to c and Q.

As shown in FIG. 2, the cylinder 1 is connected to a tangential port 50, a helical port 51, and two exhaust ports 57 and 58, respectively.

The tangential port 50 has a tip extending linearly in a plan view and connected to a cylinder 56 in a tangential direction to generate a swirling intake air flow in the cylinder 56, that is, a so-called swirl. .

The tip of the helical port 51 is spirally curved in a plan view to generate a swirl in the cylinder 56.

Intake manifold 19 of intake passage 2
Are two branch portions 26 connected to a tangential port 50 and a helical port 51 provided for each cylinder,
27, and a collector unit 25 for assembling the branch units 26 and 27 of each cylinder.

Two branch sections 2 provided for each cylinder
One of the branch portions 26 and 27 is connected to the tangential port 50, and the other branch portion 26 is connected to the helical port 51.

The swirl control valve 20 is interposed in each branch 26 connected to the tangential port 50.

When the swirl control valve 20 is closed at a predetermined low speed, most of the intake air sucked into the cylinder 56 passes through the helical port 51, and the swirling component in the cylinder 56 is strengthened.

When the swirl control valve 20 is opened as the engine speed increases, the intake air drawn into the cylinder 56 is released from the tangential port 5.
0 and the helical port 51, the intake charging efficiency is increased.

As shown in FIG. 3, each swirl control valve 20 is formed in a disk shape and has a butterfly type valve structure which is connected to a common valve shaft 32.

As shown in FIG. 4, a diaphragm type actuator 21 for rotating and driving the valve shaft 32 of each swirl control valve 20 is provided.

The link 30 is fixedly connected to one end of the valve shaft 32 via a projection 33. The tip of the rod 34 of the actuator 21 is rotatably connected to the middle of the link 30 via a pin 35.

The base end (not shown) of the rod 34 is connected to the diaphragm of the actuator 21. The actuator 21 has a diaphragm chamber in which an operation negative pressure is guided by the diaphragm, and has a built-in spring for biasing the diaphragm in the projecting direction of the rod 34.

The actuator 21 drives the swirl control valve 20 in the valve opening direction by rotating the link 30 counterclockwise in FIG. 4 by causing the rod 34 to protrude by the biasing force of a built-in spring.

When the link 30 rotates in the valve opening direction and abuts against the fixed stopper pin 37, the swirl control valve 20 is held at a fully open position substantially parallel to the passage center line of the intake passage 2.

The actuator 21 pulls the rod 34 against the spring by the negative pressure guided to the diaphragm chamber, rotates the link 30 clockwise in FIG. 4, and drives the swirl control valve 20 in the valve closing direction.

An electromagnetic actuator 42 is provided which regulates the rotation range of the valve shaft 32 against the driving force of the actuator 21 and holds the swirl control valve 20 at a predetermined opening.

The electromagnetic actuator 42 has a movable stopper pin 42 for contacting the link 30 and has a built-in solenoid (not shown) for holding the movable stopper pin 42 in a projected state.

When the electromagnetic actuator 42 from which the movable stopper pin 42 protrudes is energized, as shown by a two-dot chain line in FIG. 4, the link 30 comes into contact with the movable stopper pin 42 so that the swirl control valve 20 moves to the passage center line. In contrast, it is held at an intermediate opening position inclined at a predetermined angle.

When the electromagnetic actuator 42 into which the movable stopper pin 42 is retracted is de-energized, the swirl control valve 20 moves to the path center line by the link 30 abutting on the movable stopper pin 42 as shown by a solid line in FIG. It is held at a fully closed position that is substantially perpendicular to the position.

The diaphragm chamber of the actuator 21 is connected to the vacuum pump 8 via the negative pressure passages 22 and 11. An ON / OFF type electromagnetic valve 23 is interposed in the middle of the negative pressure passage 22. When the solenoid valve 23 is not energized, the solenoid valve 23 is at a position for guiding the atmospheric pressure to the actuator 21 via the negative pressure passage 22. When the solenoid valve 23 is energized, the solenoid valve 23 is switched to a position for opening the negative pressure passage 22 to introduce a negative pressure to the actuator 21.

The control unit 18 operates the electromagnetic valve 23 and the electromagnetic actuator 41 in accordance with the operation state of the diesel engine 1 to operate the swirl control valve 2.
The opening degree of 0 is controlled in the three stages of fully closed, intermediate opening, and fully opened as described above. The control unit 18 fully closes the swirl control valve 20 at low speed and low load to increase the swirl ratio according to the contents of the map shown in FIG. It is controlled so as to increase the intake air charging efficiency while reducing the swirl ratio while gradually opening it to full open.

The hot wire air flow meter 29 is connected to the intake passage 2.
And a hot wire (heat generating resistor) interposed upstream of the throttle valve 9. Since the resistance value of the hot wire heated by energization changes according to the intake air amount, an output Va corresponding to the intake air amount is obtained.

By the way, the accuracy of detecting the amount of intake air by the air flow meter 29 is such that the initial variation width at the time of manufacturing is in the range of about ± 3%, and the variation width due to aging may be increased to 6%. .

Therefore, it is conceivable to calibrate the intake air amount Q based on the output difference ΔVa between the output Va of the air flow meter 29 detected under predetermined operating conditions and a preset basic output V0.

However, if the flow coefficient Cv of the intake passage 2 changes due to deposits or the like on the passage wall surface of the intake passage 2, the actual intake air amount Q does not match the preset basic intake air amount Q0, There is a problem that the quantity Q cannot be calibrated with sufficient accuracy.

In particular, the helical port 5 curved in a spiral shape
In the case of the diesel engine 1 equipped with the helical port 51, carbon or the like is easily deposited on the wall surface of the helical port 51, and the flow coefficient Cv of the helical port 51 tends to be greatly reduced due to aging, and the accuracy of calibrating the intake air amount Q is deteriorated. Invite.

In view of the above, according to the present invention, the change in the flow coefficient Cv of the intake passage 2 has a small effect on the volumetric efficiency ηv determined by the configuration of the intake / exhaust system of the diesel engine 1. The output Va of the air flow meter 29 detected in the air flow meter output calibration rotation speed region and a preset basic output V are set.
The intake air amount Q is calibrated based on the output difference ΔVa from zero.

Even if the flow coefficient Cv of the intake passage 2 changes due to deposits or the like with respect to the passage sectional area, the air flow meter 2 detected in the air flow meter output calibration rotation speed region.
9 is almost unchanged, the intake air amount Q
Can be calibrated with high accuracy.

FIG. 5 shows a characteristic in which the volume efficiency ηv changes with respect to the rotation speed of the diesel engine 1. Volume efficiency ηv
Is substantially determined by the specifications of the intake / exhaust system of the diesel engine 1. The characteristic shown by the solid line in the figure is obtained when the swirl control valve 20 is opened. The characteristic shown by the broken line in the figure is obtained when the swirl control valve 20 is closed.

In the rotational speed range of approximately 1500 rpm or more, the volume efficiency ηv decreases because the flow coefficient Cv of the intake passage 2 decreases as the swirl control valve 20 closes. The effect of the change in the flow coefficient Cv of the intake passage 2 on opening and closing of the swirl control valve 20 on the volumetric efficiency ηv increases as the rotational speed increases.

In the rotation speed range lower than approximately 1500 rpm,
Dynamic effect of intake, swirl control valve 2
Even if the flow coefficient Cv of the intake passage 2 decreases with the closing of 0, the volume efficiency ηv slightly increases.

In the rotational speed range of about 1500 rpm or less, the dynamic effect of intake cancels the decrease in the flow coefficient Cv of the intake passage 2 with the closing of the swirl control valve 20, so that the swirl control valve 20 closes. However, the volume efficiency ηv hardly changes.

Therefore, by setting the air flow meter output calibration rotation speed region to a rotation speed region of 1500 rpm or less, the change in the flow coefficient Cv of the intake passage 2 is determined by the configuration of the intake / exhaust system of the diesel engine 1. The output V of the airflow meter 29 in the rotation range of the airflow meter output is little affected by the efficiency ηv.
The intake air amount Q can be accurately corrected based on the value a.

The flow chart of FIG.
9 shows a routine for correcting the output Va of the control unit 9 and is executed by the control unit 18 at regular intervals.

To explain this, first, in step 4
At 01, operating condition detection data such as the engine speed Ne, the accelerator opening Acc, the cooling water temperature Tw, the fuel temperature Tf, and the output Va of the air flow meter 29 are read.

Then, the program proceeds to a step 402, wherein it is determined whether or not the current operating condition is a time of deceleration. If it is determined that the vehicle is not decelerating, the routine ends.

If it is determined that the vehicle is decelerating, the routine proceeds to step 403, where it is determined whether the current operating condition is in the air flow meter output calibration rotation speed region. If it is determined that the rotation is not in the airflow meter output calibration rotation speed region, this routine ends.

If it is determined that the rotation speed is in the air flow meter output calibration rotation speed region, the routine proceeds to step 404, where the basic intake air amount Q0 is searched according to the engine rotation speed Ne based on the map shown in FIG. You.

Next, the routine proceeds to step 405, where the output correction value ΔVa of the air flow meter 29 is calculated as ΔVa = V0−Va.

FIG. 8 is a characteristic diagram showing the relationship between the output V of the hot wire air flow meter 29 and the intake air amount Q. The output V of the air flow meter 29 increases as the intake air amount Q increases.

Based on the characteristics of FIGS. 7 and 8, the relationship between the basic intake air amount Q0 and the basic output V0 of the air flow meter 29 in the air flow meter output calibration rotation speed region is set as shown in FIG.

The basic output V0 of the air flow meter 29 is retrieved according to the basic intake air amount Q0 based on the map of FIG. 9 set in advance.

The output correction value ΔVa calculated as the difference between the output Va of the air flow meter 29 and the basic output V0 is used as a learning value for correcting the output Va of the air flow meter 29 detected thereafter.

Therefore, the output V of the air flow meter 29
By calculating the intake air amount Q based on the value Va + ΔVa obtained by adding the output correction value ΔVa to “a”, the output Va of the air flow meter 29 is accurately corrected in accordance with the initial variation occurring during manufacturing and the variation due to aging. Thus, the detection accuracy of the intake air amount Q can be improved.

As a result, the fuel injection amount and the EGR amount of the diesel engine 1 can be precisely controlled without being affected by the variation in the output characteristics of the air flow meter 29, and the exhaust performance of the diesel engine 1 is deteriorated. Output performance can be maintained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a plan view schematically showing an intake / exhaust port.

FIG. 3 is a side view of a swirl control valve, an actuator, and the like.

FIG. 4 is a front view of an actuator and the like.

FIG. 5 is a characteristic diagram showing the relationship between the engine speed Ne and the volumetric efficiency ηv.

FIG. 6 is a flowchart showing control contents.

FIG. 7 shows an engine speed Ne and a basic intake air amount Q
FIG. 4 is a characteristic diagram showing a relationship of 0.

FIG. 8 is a characteristic diagram showing a relationship between an air flow meter output V and an intake air amount Q.

FIG. 9 shows a basic intake air amount Q0 and an air flow meter 2
9 is a characteristic diagram showing the relationship between the basic output V0 of FIG.

[Explanation of symbols]

 Reference Signs List 1 diesel engine 2 intake passage 3 exhaust passage 4 fuel injection pump 8 vacuum pump 11 negative pressure passage 18 control unit 20 swirl control valve 21 diaphragm actuator 29 air flow meter 50 tangential port 51 helical port

Claims (6)

[Claims] 1. A control device for a diesel engine having an air flow meter for detecting an intake air amount, wherein an air flow meter output calibration rotation speed region in which a change in a flow coefficient Cv of an intake passage has little effect on volumetric efficiency ηv is set. Air flow meter output Va detected in air flow meter output calibration rotation speed region and preset basic output V
A controller for a diesel engine, wherein an intake air amount Q is calibrated based on an output difference ΔVa from zero. 2. The control device for a diesel engine according to claim 1, wherein the air flow meter output calibration speed range is set to a speed range of 1500 rpm or less. 3. The method according to claim 1, wherein a judgment is made as to when the engine is decelerating, and the intake air amount Q is calibrated based on the output Va of the air flow meter detected at the time of deceleration and in the air flow meter output calibration rotation speed region. 3. The control device for a diesel engine according to 1 or 2. 4. A swirl control means for providing a plurality of intake ports for introducing intake air so as to generate an intake swirling flow in one cylinder, and for varying an intake speed distribution in each intake port. The diesel engine control device according to any one of claims 1 to 3. 5. A tangential port and a helical port for introducing intake air to one cylinder, wherein the helical port is formed in a spiral shape toward the combustion chamber so as to generate intake swirl in the cylinder. The control device for a diesel engine according to claim 4, further comprising a swirl control valve that opens and closes the tangential port according to operating conditions. 6. An air flow meter having a heating resistor interposed in an intake passage, wherein a resistance value of the heating resistor heated by energization changes according to an intake air amount. Claim 1
6. The control device for a diesel engine according to any one of claims 1 to 5.