JP2002371919A - Control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce pumping loss of a variable displacement turbocharger, an EGR valve mechanism and a variable swirl valve mechanism causing response delay at accelerating in a low rotation and a low load region of a diesel engine. SOLUTION: It is determined whether an acceleration operation state or not by an engine load detected by an engine load detecting means. When it is determined that an engine rotating speed is in a low rotation region and the engine load is in a low load region under the acceleration operation state, an exhaust turbine variable displacement mechanism of the variable displacement turbocharger is controlled to be fully opened, a variable swirl valve mechanism is controlled so that the opening is larger than a value on a variable swirl valve controlling map, and the EGR valve mechanism is controlled so that the opening is larger than a value on an EGR valve controlling map during a predetermined time. After the predetermined time passes, they are respectively controlled based on an exhaust turbine variable displacement controlling map, the variable swirl controlling map and the EGR valve controlling map.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a diesel engine provided with a device for purifying exhaust gas, and in a low rotational speed range and a low load range of the engine while taking into account not to cause deterioration of exhaust gas. The present invention relates to a device that performs control to improve drivability during acceleration operation of the vehicle.

[0002]

2. Description of the Related Art Regulations on the exhaust gas of recent internal combustion engines, especially diesel engines, are being strengthened year by year, and various types of exhaust gas such as carbon dioxide (CO2), nitrogen oxides (NOx), hydrocarbons (HC) and Various measures have been taken to meet the demand for reduction of black smoke.

The most effective means of reducing the above-mentioned CO2 is to reduce fuel consumption. In a diesel engine, a turbocharger used as a means for improving output also improves the efficiency of charging air to a cylinder to improve combustion. It is widely used as a means of improving fuel efficiency. However, the turbocharger uses the exhaust energy to drive the turbine, and the rotation of the turbine drives the compressor on the intake side to compress the fresh air and put it into the cylinder, and the characteristics of the turbine and compressor Is fixed, it is difficult to cope with a wide range of rotation speeds and load ranges, and there is a case where the ability cannot be sufficiently exhibited in a region other than the matched region. In order to solve such a problem, a variable-capacity turbocharger capable of handling from a low rotation speed to a high rotation speed has been proposed and widely used.

As a measure for reducing NOx, an exhaust gas recirculation (EGR) device is well known. this is,
An EGR passage connecting the exhaust passage and the intake passage is provided to recirculate exhaust gas containing a large amount of inert gas to the intake passage, and is injected into the cylinder together with fresh air to reduce the maximum combustion temperature during combustion to reduce NOx. Is to suppress the occurrence of.

As a countermeasure against black smoke, that is, smoke, it is effective to improve the charging efficiency by using the above-described supercharging device. However, if the intake port is fixed, the strength of the swirl greatly changes depending on the engine rotation speed, and it is difficult to obtain an optimum swirl over the entire rotation speed used by the engine. Therefore, in the low rotation speed region, the swirl is efficiently generated by narrowing a part of the intake port, and in the high rotation speed region, the intake system is opened so that the swirl is partially suppressed by opening the throttle of the intake system. There is known a so-called variable swirl system (also referred to as VSS) in which a passage shape is used to prevent overswirl.

The applicant of the present application has proposed a diesel engine equipped with the above-described variable capacity turbocharger and EGR device to improve drivability during acceleration operation at a low rotational speed and in a low load range. No. 361093 was filed. This is described below.

The variable capacity turbocharger is controlled so as to throttle a variable blade (variable nozzle vane) provided at the inlet of the turbine in order to improve the efficiency of the exhaust turbine because the exhaust energy is low in a low rotation speed and low load region.
In other words, it functions so that a predetermined expansion ratio can be obtained before and after the turbine even if the flow rate of the exhaust gas passing through the exhaust turbine is small (the exhaust turbine capacity is reduced). In the region of high rotational speed and high load, the variable blades (variable nozzle vanes) at the inlet of the turbine are largely opened to convert large exhaust energy into turbine rotation efficiently and into compressor rotational energy. That is, even when the flow rate of exhaust gas passing through the exhaust turbine is large, it is possible to function so as to obtain a predetermined expansion ratio characteristic before and after the turbine (to increase the exhaust turbine capacity).

In the steady operation region, if the above control is executed based on the map, no problem occurs. However, during the transient operation, particularly when the acceleration operation is performed at the low engine speed and the low load region of the engine, The following problems occur. Note that the acceleration operation at a low rotation speed and in a low load region is, for example, a case where a signal is transmitted from a state where a signal is waiting while traveling in an urban area, or an acceleration operation in which the speed is slightly increased from the low speed operation. It is.

As described above, the variable capacity turbocharger can efficiently rotate the turbine with little exhaust energy even in a low rotation and low load region. In the case where an EGR device is provided, by providing an outlet for the EGR gas upstream of the turbine in the exhaust passage, a pressure increase in the exhaust passage due to the throttle of the turbine inlet acts, and the EGR gas is transferred to the intake passage side. The effect that more can be taken out can be obtained. However, on the other hand, reducing the inlet of the exhaust turbine increases the pressure in the exhaust passage, causing pumping loss during the exhaust stroke. When driving, it causes a feeling of rattling.

In view of the above, according to the above-mentioned prior application, the present applicant performs control so as to open the variable nozzle vane at the inlet of the variable displacement turbocharger for a predetermined period during the acceleration operation in the low rotation and low load range. We have proposed a control system for a diesel engine configured to temporarily reduce pumping loss and improve drivability during acceleration operation under low load conditions.

By performing such control, the pressure generated in the exhaust passage is released and the pumping loss is reduced in the acceleration operation state in the low rotation and low load region. Therefore, the rotation speed of the engine quickly increased, the feeling of backlash was improved, and the drivability was improved. By the way, opening the nozzle at the turbine inlet of the variable capacity turbocharger weakens the function of the turbine.However, in the low load region, the air in the cylinder is originally sufficient for the fuel injection amount, and the acceleration operation state Since it is a temporary release when it is detected, the rotational speed of the turbocharger itself does not change extremely (the effect of the inertia of the turbine compressor itself is larger than the response due to pressure change), so the smoke is worsened Is extremely small.

On the other hand, the EGR valve mechanism has a large opening so as to maximize the EGR amount in a low rotation and low load range, and has a small opening so that the higher the rotation and load, the smaller the EGR amount. The valve control map has been set. In accordance with this, the throttle opening of the intake throttle valve provided in the intake passage is set to be large in the low rotation and low load region, and the throttle opening is set to be smaller as the rotation is higher and the load is higher.

Normally, the EGR valve used for the above control does not use a 100% opening even when the EGR flow rate is maximized. This is necessary also in the sense of giving the EGR control freedom. The EGR rate is in a trade-off relation with the generation of smoke, and must be controlled so as not to excessively reduce the amount of EGR while sufficiently suppressing NOx. In other words, this means that the EGR valve opening control map is tuned in accordance with the change in the exhaust gas regulation value and the change in the fuel injection control, and even if the change is made, it is not necessary to replace the EGR valve with another EGR valve having a large flow rate. Therefore, even if the EGR flow rate is maximum on the control map,
The opening of the R valve is controlled so as to obtain a desired EGR flow rate by using an opening of about 80% (maximum of this opening) and a combination of the opening with an intake throttle valve provided in the intake passage. .

As an example of the prior art, a diesel engine provided with two intake ports having a variable swirl system will be described. In the conventional diesel engine, the cylinder head is provided with two intake ports communicating with the inside of the cylinder. One of the intake ports is formed as a helical port in which a swirling flow is easily generated in order to generate a strong swirl in the cylinder, and the other intake port is a swirl generated by passing through the helical port which is the one intake port. Is formed in a tangential port shaped so as to cancel out swirling flow.

The tangential port is provided with a valve for opening and closing the passage, a so-called variable swirl valve, and a variable swirl valve mechanism including an actuator for driving the variable swirl valve. The actuator is connected to a negative pressure tank or the like. The drive is controlled by the controller.

The controller stores a variable swirl valve control map. The variable swirl valve control map uses at least the engine rotation speed detected by the engine rotation speed detection means as a parameter, and closes the variable swirl valve in a region where the engine rotation speed is low, and a variable swirl valve in a region where the engine rotation speed is high. Is set to open.

By executing the control as shown in the above map, in the low rotation speed region, only the helical port communicates with the cylinder, and the swirling flow generated by the helical port is injected into the cylinder from the intake valve. The shape of the helical port is tuned so that an appropriate swirl is generated when the helical port is independently connected to the cylinder in the low rotation speed region. On the other hand, when the high rotational speed region is reached, if only this helical port is communicated with the cylinder, overswirl will occur, and the intake air from the tangential port will be communicated with the cylinder through the intake valve. As a result, the swirl generated by the helical port collides with the intake air injected into the cylinder by the tangential port, and the swirling flow is moderately attenuated. As a result, the engine is operated at a high rotational speed. Nevertheless, a moderate swirl will be given.

[0018]

In response to the increasing demand for reduction of exhaust gas as described above, the use of a variable capacity turbocharger in combination with an EGR device or a variable swirl system has recently increased.

The inventor of the present application has conducted various studies on the EGR control. As a result, when the EGR passage is opened and closed, the pumping loss is smaller when the EGR passage is opened. found. This is because when the EGR is performed, the EGR passage also becomes a part of the intake passage for the cylinder in the intake stroke, and the exhaust passage for the cylinder in the exhaust stroke. This is due to the influence of the exhaust resistance.

As described above, in the low rotation speed and low load state, EG
At present, although the R flow rate is maximized, the EGR control valve uses an opening of about 80% at the maximum. That is, this EGR control valve has a pumping loss even at the maximum opening on the control map, and it has been found that the EGR control valve causes a feeling of rattling at the time of acceleration in the low rotation and low load region.

Incidentally, the EGR control valve is closed in the high-speed and high-load region. However, in this region, the output of the engine is extremely large, and pumping loss caused by closing the EGR control valve hardly causes a problem.

Similarly to the EGR, the variable swirl system also generates a pumping loss during the intake stroke due to the fact that a part of the intake air is throttled at a low rotation speed and a low load. It has been found that the drivability in an accelerated driving state at a low load is deteriorated.

That is, the variable capacity turbocharger and E
When the GR or the variable swirl system is used together, the drivability is not sufficiently improved only by opening the nozzle vane at the turbine inlet of the variable capacity turbocharger when the vehicle is in an acceleration operation state at a low rotation and a low load. There is still room for improvement to eliminate pumping losses.

[0024]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, an exhaust turbine provided with an exhaust turbine variable displacement mechanism disposed in an exhaust passage of an engine and an intake passage of the engine are disposed. A variable capacity turbocharger having an intake compressor, an EGR passage communicating between an exhaust passage upstream of the exhaust turbine and an intake passage downstream of the intake compressor, and an EGR valve mechanism disposed in the EGR passage. A diesel engine control device that controls the exhaust turbine variable displacement mechanism and the EGR valve mechanism in accordance with the engine speed and the engine load, an engine speed detecting means for detecting an engine speed, and an engine load Engine load detecting means, and at least the engine speed and the engine load. The exhaust turbine is set as a parameter so that the capacity of the exhaust turbine is smaller as the engine is in a low rotation region and a low load region, and is set so as to be larger in a high rotation region and a high load region. The variable displacement control map, at least the engine speed and the engine load are used as parameters, and the opening of the EGR valve is increased as the engine is in the low engine speed region and the engine is in the low engine load region. The E is set so that the opening of the EGR valve becomes smaller as
An EGR valve mechanism and an exhaust turbine based on an EGR valve control map for determining a GR valve, detection signals from the engine rotational speed detecting means and the engine load detecting means, the exhaust turbine variable displacement control map, and the EGR valve control map; A controller for controlling the variable displacement mechanism; the controller determines whether or not the engine is in an accelerating operation state based on the engine load detected by the engine load detecting means; If it is determined that the engine load is in the low load range, the exhaust turbine variable displacement mechanism is controlled at a value larger than the control value of the exhaust turbine variable displacement control map for a predetermined period, and the EGR valve mechanism is controlled. Is larger than the control value set on the EGR valve control map. Controls in, to provide a control apparatus of a diesel engine, characterized in that.

Further, in the present invention, a variable displacement turbocharger having an exhaust turbine provided in an exhaust passage of an engine and having an exhaust turbine variable displacement mechanism and an intake compressor provided in an intake passage of the engine; A variable swirl valve mechanism that changes the swirl in the cylinder by changing the passage area of the intake port of the engine; and controls the exhaust turbine variable displacement mechanism in accordance with the engine speed and the engine load, while controlling the engine speed. The control device for a diesel engine that controls the variable swirl valve mechanism in response to the engine rotational speed, an engine load detecting means for detecting an engine rotational speed, an engine load detecting means for detecting an engine load, and at least the engine rotational speed and the engine load. Parameter and low in the low engine speed range. An exhaust turbine variable displacement control map set so that the capacity of the exhaust turbine decreases as the load area increases, and the exhaust turbine capacity increases as the engine speed increases and the load area increases. A variable swirl valve control map that determines to close the variable swirl valve mechanism in the low rotation speed region and to open the variable swirl valve mechanism in the high rotation speed region, the engine rotation speed detection means and the engine load. A controller for controlling the exhaust turbine variable displacement mechanism and the variable swirl valve mechanism based on the detection signal from the detection means and the exhaust turbine variable displacement control map and the variable swirl valve control map; Whether the engine is in an accelerated operation state due to the engine load detected by the engine load detection means If it is determined that the engine speed is in the low rotation region and the engine load is in the low load region in the acceleration operation state, the exhaust turbine variable displacement mechanism is A control device for a diesel engine, wherein the control device controls the variable swirl valve mechanism with a value larger than a control value set on the map while controlling the variable swirl valve mechanism with a value larger than a control value of the variable displacement control map. I do.

Further, according to the present invention, there is provided a variable displacement turbocharger having an exhaust turbine disposed in an exhaust passage of an engine and having an exhaust turbine variable displacement mechanism, and an intake compressor disposed in an intake passage of the engine. An EGR passage communicating between an exhaust passage upstream of the exhaust turbine and an intake passage downstream of the intake compressor;
An EGR valve mechanism disposed in the GR passage, a variable swirl valve mechanism for changing a swirl in the cylinder by changing a passage area of an intake port of the engine, and the exhaust gas according to an engine speed and an engine load. In a diesel engine control device that controls a turbine variable displacement mechanism and the EGR valve mechanism and controls the variable swirl valve mechanism according to the engine speed, an engine speed detection unit that detects the engine speed, an engine load Engine load detecting means for detecting
At least the engine speed and the engine load are used as parameters, and the capacity of the exhaust turbine is reduced as the load becomes lower in the low speed range of the engine and the capacity of the exhaust turbine becomes smaller as the load becomes higher in the high speed range and the high load range. An exhaust turbine variable displacement control map that is set to be large, and at least the engine speed and the engine load as parameters, such that the opening degree of the EGR valve increases as the engine speed decreases and the engine load decreases. An EG for determining the EGR valve such that the opening degree of the EGR valve decreases as the rotation speed and the load range increase.
An R valve control map, a variable swirl valve control map that determines at least the engine rotation speed as a parameter and closes the variable swirl valve mechanism in a low rotation speed region and opens the variable swirl valve mechanism in a high rotation speed region;
The exhaust turbine variable displacement mechanism based on the detection signals from the engine rotation speed detection means and the engine load detection means, the exhaust turbine variable displacement control map, the EGR valve control map, and the variable swirl valve control map;
A controller for controlling the GR valve mechanism and the variable swirl valve mechanism; the controller determines whether or not the engine is in an accelerating operation state based on an engine load detected by the engine load detecting means; When it is determined that the speed is in the low rotation region and the engine load is in the low load region, the exhaust turbine variable displacement mechanism is set to a value larger than the control value of the exhaust turbine variable displacement control map for a predetermined period. Control, the opening degree of the EGR valve mechanism is controlled at a value larger than the control value set on the EGR valve control map, and the variable swirl valve mechanism is set larger than the control value set on the map. A control device for a diesel engine, wherein the control device is controlled by a value.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment relating to a diesel engine control device according to the present invention will be described below with reference to FIGS. In FIG. 1, an engine body 2 including a cylinder block, a cylinder head, and the like is provided with an intake manifold 3 forming a part of an intake passage and an exhaust manifold 4 forming a part of an exhaust passage. An intake pipe 5 constituting a part of an intake passage is connected to the intake manifold 3, and an air cleaner 6 for purifying intake air is arranged at the most upstream portion of the intake pipe 5. The intake air purified by the air cleaner 6 is supplied to the intake pipe 5
Through the intake manifold 3, two intake ports 21, 2
2, and is supplied into the cylinder 20. One intake port 21 is formed as a helical port having a shape in which a swirling flow is likely to occur, and the other intake port 22 is formed as a tangential port having a shape in which intake air with high straightness is injected into a cylinder. The intake ports 21 and 2
The intake valves 23 and 24 are disposed at the outlets 2 respectively. An exhaust pipe 7 forming a part of an exhaust passage is connected to the exhaust manifold 4, and exhaust gas generated in the cylinder 20 is exhausted through the exhaust ports 26a and 26b, the exhaust manifold 4, and the exhaust pipe 7. .
Exhaust valves 25a and 25b are provided at the inlets of the exhaust ports 26a and 26b, respectively. An exhaust pipe 7 forming a part of an exhaust passage is provided in the exhaust manifold 4.
Is connected, and the exhaust gas generated in the cylinder is discharged through the exhaust manifold 4 and the exhaust pipe 7.

The illustrated diesel engine is provided with a variable capacity turbocharger 8 for supercharging intake air. This turbocharger 8 has an exhaust turbine 81 provided with an exhaust turbine variable capacity mechanism 40 (V1) provided in the exhaust pipe 7, and an intake compressor device 82 provided in the intake pipe 5.

The exhaust turbine variable displacement mechanism 40 (V1) of the illustrated embodiment is configured such that the exhaust passage area on the upstream side of the turbine impeller 810 is variable,
A variable nozzle vane 41 for controlling the exhaust turbine capacity of 0 (V1) is provided. Exhaust turbine variable capacity mechanism 40
The structure of (V1) and its operation will be further described with reference to FIG.

As shown in FIG. 2, the turbine impeller 81
A plurality of variable nozzle vanes 41 are arranged around 0 at predetermined intervals in the circumferential direction. Each variable nozzle vane 4
1 surrounds the variable nozzle vane 41 via a nozzle vane shaft 42, a lever 43, a slider 44, and a pin 45 (all of which are shown at only two places in FIG. 2 but are installed on all the variable nozzle vanes). Ring 4
6. When the ring 46 rotates in the circumferential direction, the variable nozzle vane 41 rotates around the nozzle vane shaft 42, and the inclination angle changes. Therefore, the rotation of the ring 46 allows the variable nozzle vane 41
Is adjusted, and the opening and closing of the variable nozzle vane 41 continuously changes the exhaust passage area on the upstream side of the turbine impeller 810. In FIG. 2, when the ring 46 rotates clockwise (in the direction of the arrow), the variable nozzle vane 41 is rotated.
Is small as shown by the two-dot chain line, so the exhaust passage area on the upstream side of the turbine impeller 810 is small. As described above, when the exhaust passage area on the upstream side of the turbine impeller 810 changes continuously due to the opening and closing of the variable nozzle vane 41, the speed of the exhaust gas flow colliding with the turbine impeller 810 changes. The characteristics can be changed, that is, the rotation speed of the exhaust turbine can be controlled. As described above, in the illustrated embodiment, the variable nozzle vane 41 functions as an exhaust passage area varying unit that varies the exhaust passage area on the upstream side of the turbine impeller 810.

The ring 46 for adjusting the opening of the variable nozzle vane 41 is rotated by a diaphragm type actuator 48 via a connect plate 47. As shown in FIG. 2, a negative pressure is introduced from a negative pressure tank (not shown) into a negative pressure chamber 49 constituting the actuator 48 via a negative pressure introduction passage 50. The ratio of the negative pressure introduced from the negative pressure tank into the negative pressure chamber 49 is adjusted by an electromagnetic control valve (not shown) provided in the negative pressure introduction passage 50, and the opening is controlled by the duty ratio supplied to the electromagnetic control valve. Is done.
As shown in FIG. 2, the actuator 48 normally urges the rod 52 connected to the connect plate 47 rightward by a spring 51 provided in the negative pressure chamber 49 to rotate the ring 46 clockwise. When the internal pressure of the negative pressure chamber 49 decreases due to the operation of an electromagnetic control valve (not shown), the rod overcomes the urging force of the spring 51 and moves to the left to rotate the ring 46 counterclockwise. Therefore, the internal pressure of the negative pressure chamber 49 is adjusted by the duty ratio for energizing the electromagnetic control valve, and the actuator 48
And the rotation of the ring 46, the opening of the variable nozzle vane 41 is adjusted. The variable nozzle vane 41
Is adjusted so that the opening degree becomes smaller as the duty ratio becomes larger, and conversely, the opening degree becomes larger as the duty ratio becomes smaller.

In the illustrated diesel engine, the exhaust pipe 7 upstream of the exhaust turbine 81 provided with the exhaust turbine variable displacement mechanism 40 (V1) communicates with the intake pipe 5 downstream of the intake compressor 82. An exhaust gas recirculation (EGR) passage 9 is provided. E in the EGR passage 9
An EGR valve mechanism 11 (V2) including a GR valve and an EGR valve drive actuator is provided.
The EGR valve mechanism 11 (V2) is connected to a negative pressure tank (not shown), and the controller 10 described later controls the amount of negative pressure supplied to the EGR valve drive actuator in accordance with the operation state, thereby controlling the EGR valve mechanism 11 (V2). The opening degree, that is, the EGR rate is controlled.

An intake throttle valve 12 is disposed in the intake passage 5 upstream of a connection portion between the intake passage 5 and the EGR passage, and an actuator connected to a negative pressure tank (not shown) is connected to a controller described later. The opening degree is controlled by ten instruction signals. Since the control of the intake throttle valve is not the main configuration of the present invention, a detailed description thereof will be omitted.

The illustrated diesel engine has a variable swirl valve mechanism 30 (V1) disposed on the other intake port 22 side formed in the tangential port. The variable swirl valve mechanism 30 (V1) includes a so-called variable swirl valve provided in an intake port 22 formed in a tangential port, and an actuator for driving the variable swirl valve.
By changing or opening and closing the passage area of the cylinder 2
Adjusts the strength of the swirl generated within 0.

FIG. 3 shows the peripheral portion of the cylinder 20 shown in FIG.
The operation of the variable swirl valve mechanism will be described based on FIG. In addition,
Although only one cylinder is shown in FIG. 1, other cylinders are omitted.

FIG. 3 shows the variable swirl valve mechanism 30 (V3). The exhaust valve, the exhaust port, and the cylinder 20
The injectors and the like arranged at the center of the are omitted. A negative pressure actuator and a negative pressure tank (not shown) are connected to the variable swirl valve mechanism 30 (V3).
The variable swirl valve mechanism 30 (V3) is controlled to open and close by controlling the negative pressure of the actuator in accordance with an instruction signal from a controller 10 described later.

In the low rotation speed region, only the helical port communicates with the cylinder and the swirling flow generated by the helical port is injected into the cylinder by the controller 10. The shape of the helical port is tuned so that an appropriate swirl is generated when the helical port is independently connected to the cylinder in the low rotation speed region. On the other hand, when the rotation speed is in the high rotation speed region, if only this helical port is communicated with the inside of the cylinder, overswirl occurs, so that the intake air from the tangential port is injected into the cylinder. As a result, the swirl generated by the helical port collides with the intake air injected into the cylinder by the tangential port, and the swirling flow is moderately attenuated. As a result, the engine is operated at a high rotational speed. Nevertheless, a moderate swirl will be given.

The controller 10 comprises a microcomputer, a central processing unit (CPU) for executing various arithmetic programs, a read-only memory (ROM) for storing various arithmetic programs and map data to be executed by the CPU, a CPU, A random access memory (RAM) for temporarily storing the calculation results of the above, data input from each sensor, and the like, a timer (T) for counting time, and a counter (F). The ROM stores a fuel injection amount map (map), an exhaust turbine variable displacement control map (map), and an EGR valve control map (m
ap), a variable swirl valve control map (map), and an acceleration operation region determination map (map) are stored.
The controller 10 having the above-described configuration is configured to control the accelerator opening signal (Ac) from the accelerator opening sensor 13 and the engine rotation speed signal (from the engine rotation speed sensor 14 as engine rotation speed detecting means for detecting the engine rotation speed). Ne) and the like, and based on the accelerator opening signal (Ac) and the engine rotation speed signal (Ne), the exhaust turbine variable displacement mechanism 81 (V1), EG
A control signal is output to the R valve mechanism 11 (V2), the variable swirl valve mechanism (V3), and the like.

Next, the control executed by the controller 10 will be described with reference to the flowchart shown in FIG. FIG. 4 shows a flowchart of the engine control executed by the controller 10 based on the present invention. This flowchart shows the exhaust turbine variable displacement mechanism 81 (V1), E
Although a flowchart for controlling the GR valve mechanism 11 (V2) and the variable swirl valve mechanism 30 (V3) is shown, in reality, the controller 10 performs integrated control of the engine, and controls the fuel injection of the engine and the intake throttle. It also performs control such as valve control and abnormality diagnosis.

Control is started based on this flowchart when the start mode in which the fuel injection amount is increased ends and the normal RUN mode is entered. As will be described later, an initial value Qt which is the imaginary previous value of the initially calculated fuel injection amount Qt (1) so that acceleration is not detected immediately after the transition.
(0) is given Full (maximum value). Qt
(0) is not actually executed as the fuel injection amount. The counter F is also provided with F = 0 as an initial value.

Step S1: Accelerator opening (Ac) and engine rotation speed (Ne) are obtained from the accelerator opening sensor and the engine rotation speed sensor as the engine rotation speed detecting means.
Read.

Step S2: The current target fuel injection amount (Qt (i)) is calculated from the fuel injection amount map (map) shown in FIG. 5 using (Ac) and (Ne) as parameters read in step S1. . The target fuel injection amount is treated as a parameter indicating an engine load, which will be described later, and the calculation of the target fuel injection amount functions as an engine load detecting unit in the present invention.

Step S3: (Ne) read in step S1 and (Q) calculated in step S2
The basic exhaust turbine control value (Tm) is substituted into the exhaust turbine control value (Tn) from the exhaust turbine variable displacement control map (map) shown in FIG. 6 using t (i)) as a parameter. This map is an engine speed value (Ne).
Using the engine load value (Qt (i)) as a parameter, the variable turbine nozzle is closed at low engine speed and low load, and the variable turbine nozzle is opened at high engine speed and high engine speed. It has become.

Step S4: The engine speed (Ne) read in step S1 and the target fuel injection amount Qt as the engine load calculated in step S2
Using (i) as a parameter, the basic EGR valve control value (Em) obtained from the EGR valve control map (map) shown in FIG. 7 is substituted for the EGR valve control value (Ev).
As described above, the EGR valve control map (map
) Uses the engine rotation speed Ne and the target fuel injection amount (Qt (i)) as an engine load value as parameters, and the degree of opening of the EGR valve increases as the rotation speed decreases and the load range decreases. The opening degree of the EGR valve is set such that the opening degree of the EGR valve becomes smaller as the rotational speed is higher and the load is higher.

Step S5: (Ne) read in step S1 and calculated in step S2 (Q
The basic swirl valve control value (Vm) is substituted into the variable swirl valve control value (Vn) from the variable swirl valve control map (map) shown in FIG. 8 using t (i)) as a parameter. This map is an engine speed value (Ne).
Target fuel injection amount as engine load value (Qt (i))
With the parameter as a parameter, the variable swirl valve is closed at a low rotation speed, and the variable swirl valve mechanism is opened at a high rotation speed.In a low load region, the engine rotation speed is slightly higher than in a high load region. The variable swirl valve mechanism is also closed. In the present embodiment, the control is based on two values of only opening and closing, but the control may be performed in multiple stages.

Step S6: It is determined whether or not a counter F which changes depending on whether or not the vehicle is accelerating is "0". As described above, since F = 0 is given as the initial value, F = 0 until acceleration is detected. If acceleration has not been detected in the previous routine, that is, if F = 0, the process proceeds directly to step S7. If F = 0 is not satisfied, it is determined that the vehicle is in the acceleration operation state in the previous routine, and the control is being performed in the acceleration operation state. Skip step S7 and proceed to step S8.

Step S7: It is determined whether or not the engine has shifted to an accelerated operation state. Whether or not the engine has shifted to the accelerated operation state is determined based on the change in the fuel injection amount detected as the engine load, and the previously calculated fuel injection amount (Qt (i-1)) and the current fuel injection amount (Qt (I))
Is determined based on whether or not the amount of change is equal to or greater than a predetermined value (Qacc).
The predetermined value (Qacc) is set as a reference that can detect a small change in the fuel injection amount as in the case where the vehicle starts after waiting for a traffic light. If it is determined that the vehicle is in the acceleration operation state, the process proceeds to step S8. In the acceleration determination, the fuel injection amount (Qt (i)) is used as the engine load, but a value serving as an index of another engine load may be used.
For example, the change amount of the accelerator opening (Ac) or the change amount of the detection value of the torque sensor provided on the drive shaft of the engine can be substituted.

Step S8: Current fuel injection amount Qt
Based on (i) and the engine rotation speed Ne, it is determined whether or not the vehicle is accelerating in a low-load and low-speed region using an acceleration operation region determination map (map) as shown in FIG. This region shape is a low-rotation low-load region shape in the exhaust turbine variable displacement control map (map) shown in FIG. 6, that is, a region shape in which the throttle of the variable nozzle vane of the exhaust turbine variable displacement mechanism of the variable displacement turbocharger is large (FIG. 6). It is preferable to set the area in consideration of the hatched area in FIG.

In this embodiment, the low-speed low-load region is determined by using the map. However, Ne <Nelow (low-speed region) & Qt (i) <Qlow (low-load region)
May be determined. Also in this case, a low-speed, low-load region is defined within a region of the exhaust turbine variable displacement control map where the variable nozzle vanes are throttled. With such a determination step, the storage area of the map and the execution load of the controller 10 by the reference program are reduced. If it is determined that the acceleration operation has been performed in the low-load low-rotation speed region, the process proceeds to the next step S9.

Steps S9 and S10: In step S9, when the acceleration operation is detected, it is determined whether or not the counter F is smaller than a set value (Ftimer) (F <Ftimer?).
Is determined. The counter F is incremented by one each time the program routine is executed (step S10), and the set value (Ft) of step S9 is set.
imer) sets the number of times (that is, the period) in which the routine of step S10 and subsequent steps are executed. For example, if the setting value of step S9 is “Ftimer = 1”, the routine of step S12 and subsequent steps described later
It ends only when executed once. In the present embodiment, the counter F is used for the measurement of the predetermined period, but it goes without saying that the measurement may be performed by the time measurement using the timer function (T) of the controller. The set value Ftimer can be set arbitrarily according to the characteristics of the engine.

Step S11: If the determination in step S8 and step S9 is No, it means that the control during acceleration operation is not necessary anymore. The value of F that has been counted is reset (F = 0).

Step S12: It is determined in step S12 that the vehicle is in the acceleration operation state and the acceleration operation has been performed in the low-speed and low-load region.
The basic exhaust turbine control value Tm and the basic EGR control value Em assigned to the control values Tn, Ev, and Vn obtained in
And the basic variable swirl valve control value Vm is discarded, Tn is the maximum value of the exhaust turbine control value, and Ev is the maximum value of the exhaust turbine control value.
The maximum value Vopen of the variable swirl valve control value is substituted for the maximum values Eopen and Vn of the GR valve control values.

Step S13: The exhaust turbine control value (Tn), EGR valve control value (Ev) and variable swirl valve control value (Vn) substituted in each of the above steps are converted into the exhaust turbine variable displacement mechanism 81 (V1) and the EGR valve. Mechanism 11 (V2) and the variable swirl valve mechanism 30 (V
Output to 3). That is, when it is determined in step S7 that the vehicle is not in the acceleration operation state, the acceleration is in the high load state or the high rotation speed state even in the acceleration operation state in step S8. If the control for each control object after the acceleration operation has been completed in step S9, the exhaust turbine variable displacement control map (map) and the EGR
The values (basic control values) of the valve control map (map) and the variable swirl valve control map (map) are output as they are. If the answer is yes in step S7, step S8, or step S9, it is determined from the exhaust turbine variable capacity control map (map), the EGR valve control map (map), and the variable swirl valve control map (map). Value (basic control value) is discarded, and the exhaust turbine variable displacement mechanism 81 (V1), EG
R valve mechanism 11 (V2) and variable swirl valve mechanism 3
0 (V3) to be fully open (Topen, Eop
en, Vopen) as a control value.

In the above-described embodiment, the control value of each control object is set to fully open in response to the detection of the acceleration operation state in the low-speed low-load region, but at least the opening degree obtained from each control map is obtained. It is clear from the technical idea that the effect of the present invention can be obtained if the control is performed so as to be larger than the above.

In this embodiment, the variable capacity turbocharger, the EGR device and the variable swirl system are used together (corresponding to claim 3). However, only the variable capacity turbocharger and the EGR device are used together. It is apparent that the technical idea of the present invention can be individually realized in the case where the above-mentioned method is applied (corresponding to claim 1), and also in the case where only the variable capacity turbocharger and the variable swirl system are used together (corresponding to claim 2).

In the present embodiment, a variable swirl valve mechanism is presented as a variable swirl valve mechanism. However, in a variable swirl system in which the swirl intensity is controlled by changing the passage area of the intake port, the intake is controlled. 1
It is clear that the present invention is applicable regardless of the type of the variable swirl valve mechanism.

[0057]

As described above, according to the present invention, when the acceleration operation state is detected in the low rotation speed and low load range, the variable displacement of the exhaust turbine variable displacement mechanism provided in the variable displacement turbocharger which causes pumping loss. While the throttle of the nozzle vane is fully opened, the throttle of the EGR passage is set to E
The GR valve mechanism is controlled and operated so that its opening is larger than a control value normally output to the GR valve mechanism. Therefore, when starting from a traffic light or when accelerating in a low rotation and low load region, the engine rotation speed is rapidly increased, and as a result, the feeling of backlash of the vehicle can be eliminated and drivability can be improved.

Further, when an acceleration operation state in a low-rotation low-load region is detected, a throttle of a variable nozzle vane of an exhaust turbine variable displacement mechanism provided in a variable displacement turbocharger which causes a pumping loss is fully opened. The throttle of the variable swirl valve mechanism of the variable swirl system is controlled and operated so that its opening becomes larger than a control value normally output to the variable swirl valve mechanism. Therefore, when starting from a traffic light or when accelerating in a low rotation and low load region, the engine rotation speed is rapidly increased, and as a result, the feeling of backlash of the vehicle can be eliminated and drivability can be improved.

Further, when an acceleration operation state is detected in a low-rotation low-load region, the throttle of the variable nozzle vane of the variable displacement mechanism of the exhaust turbine provided in the variable displacement turbocharger, which causes pumping loss, is fully opened. , The throttle of the EGR passage is controlled so that its opening becomes larger than a control value normally output to the EGR valve mechanism, and the throttle of the variable swirl valve mechanism of the variable swirl system is changed to the variable swirl valve mechanism. Is controlled and actuated so that the opening degree becomes larger than a control value normally output to the controller. Therefore, when starting from a traffic light or when accelerating in a low-speed low-load region, the engine speed is quickly increased, and as a result, the feeling of backlash of the vehicle is eliminated, and the drivability can be further improved. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an engine control device for a diesel engine based on the present invention.

FIG. 2 is an explanatory view of the operation of the variable displacement turbocharger of FIG. 1;

FIG. 3 is an operation explanatory diagram of the variable swirl device of FIG. 1;

FIG. 4 is a control flowchart executed by a controller constituting the engine control device of FIG. 1;

FIG. 5 is a fuel injection amount control map.

FIG. 6 is an exhaust turbine variable displacement control map.

FIG. 7 is an EGR valve control map.

FIG. 8 is a variable swirl valve control map.

FIG. 9 is an acceleration determination area determination map.

[Explanation of symbols]

 2: Diesel engine 3: Intake manifold 4: Exhaust manifold 5: Intake passage 6: Air cleaner 7: Exhaust passage 8 (81, 82): Variable capacity turbocharger 810: Turbine impeller 9: EGR passage 10: Controller 11: EGR valve mechanism 12: intake throttle valve 13: accelerator opening sensor 14: engine rotation sensor 20: cylinder 21, 22: intake port 23, 24: intake valve 25a, 25b: exhaust valve 26a, 26b: exhaust port 30: variable swirl valve mechanism 40 : Exhaust turbine variable capacity mechanism 41: Variable nozzle vane 42: Nozzle vane shaft 43: Lever 44: Slider 45: Pin 46: Ring 47: Connect plate 48: Actuator 49: Negative pressure chamber 50: Negative pressure introduction passage 51: Spring 52: Rod

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02B 37/00 302 F02B 37/00 302F 37/12 302 37/12 302D 302F 37/24 F02D 13/02 B F02D 13/02 L 21/08 301B 21/08 301 23/00 J 23/00 P 41/02 380D 41/02 380 380E 380G 43/00 301N 43/00 301 301R 301U 45/00 301A 45/00 301 312H 312 314E 314 F02B 37/12 301Q F term (reference) 3G005 DA02 EA04 EA15 EA16 FA02 FA35 GA04 GC07 GD13 GD17 GE09 GE10 HA12 JA39 JB02 3G062 AA01 AA05 BA04 BA06 CA04 CA07 CA08 DA01 EA05 GA04 GA05 GA04 GA05 GA06 BA21 CA03 CA04 CA09 DA02 DA15 EA11 EB09 EB12 EC01 FA10 FA33 3G092 AA02 AA10 AA17 A A18 DB03 DC06 DC09 EA01 EA11 EA17 EC01 FA03 FA24 GA05 GA06 GA12 GA17 GA18 HE01Z HF08Z 3G301 HA02 HA11 HA13 HA17 JA02 JA03 KA06 KA08 KA09 KA12 KA24 KA25 LA00 LA05 NC04 ND02 NE23 PE01Z PF03Z

Claims (3)

[Claims] 1. A variable displacement turbocharger having an exhaust turbine disposed in an exhaust passage of an engine and having an exhaust turbine variable displacement mechanism, and an intake compressor disposed in an intake passage of the engine, and an upstream side of the exhaust turbine. An EGR passage connecting the exhaust passage of the intake air passage and the intake passage downstream of the intake compressor, and an EGR passage provided in the EGR passage.
A GR valve mechanism, the exhaust turbine variable displacement mechanism and the E valve according to an engine speed and an engine load.
In a diesel engine control device for controlling a GR valve mechanism, an engine speed detecting means for detecting an engine speed, an engine load detecting means for detecting an engine load, and at least an engine speed and an engine load as parameters, The exhaust turbine variable displacement control map is set so that the capacity of the exhaust turbine becomes smaller as the load becomes lower in the low rotation range and the capacity of the exhaust turbine becomes larger as the load becomes higher and the rotation range increases. And at least the engine speed and the engine load as parameters, the opening degree of the EGR valve increases as the engine speed decreases and the engine load decreases, and the EGR valve increases as the engine speed increases and the engine load increases. EG that determines the EGR valve so that the opening of the EG becomes small
An EGR valve mechanism and an exhaust turbine variable capacity mechanism are controlled based on an R valve control map, detection signals from the engine rotational speed detecting means and the engine load detecting means, the exhaust turbine variable capacity control map, and the EGR valve control map. The controller determines whether or not the vehicle is in an accelerating operation state based on the engine load detected by the engine load detecting means. In the accelerating operation state, the engine rotational speed is in a low rotation region, and the engine load is If it is determined that the engine is in the low load range, the exhaust turbine variable displacement mechanism is controlled at a value larger than the control value of the exhaust turbine variable displacement control map for a predetermined period, and the opening of the EGR valve mechanism is decreased. E
A control device for a diesel engine, wherein the control is performed at a value larger than a control value set on a GR valve control map. 2. A variable displacement turbocharger having an exhaust turbine disposed in an exhaust passage of an engine and having an exhaust turbine variable displacement mechanism and an intake compressor disposed in an intake passage of the engine, and a passage of an intake port of the engine. A variable swirl valve mechanism for changing the swirl in the cylinder by changing the area; and a variable swirl mechanism for controlling the exhaust turbine variable displacement mechanism in accordance with the engine speed and the engine load and for controlling the engine speed in accordance with the engine speed. In a control device for a diesel engine that controls a valve mechanism, an engine speed detecting means for detecting an engine speed, an engine load detecting means for detecting an engine load, and at least the engine speed and the engine load as parameters, Exhaust the lower the load in the low rotation range An exhaust turbine variable displacement control map that is set so that the turbine capacity is reduced and the exhaust turbine capacity is increased as the engine speed and load range increase, and at least the engine speed as a parameter, A variable swirl valve control map for deciding to close the variable swirl valve mechanism in the speed range and to open the variable swirl valve mechanism in the high speed range; and detection signals from the engine rotational speed detecting means and the engine load detecting means. And a controller for controlling the exhaust turbine variable displacement mechanism and the variable swirl valve mechanism based on the exhaust turbine variable displacement control map and the variable swirl valve control map. It is determined whether or not the vehicle is in the accelerating operation state based on the In this state, when it is determined that the engine rotation speed is in the low rotation region and the engine load is in the low load region, the exhaust turbine variable displacement mechanism is controlled by the control value of the exhaust turbine variable displacement control map for a predetermined period. Controlling the variable swirl valve mechanism with a value larger than a control value set on a map. 3. A variable displacement turbocharger having an exhaust turbine disposed in an exhaust passage of an engine and having an exhaust turbine variable displacement mechanism and an intake compressor disposed in an intake passage of the engine, and an upstream side of the exhaust turbine. An EGR passage connecting the exhaust passage of the intake air passage and the intake passage downstream of the intake compressor, and an EGR passage provided in the EGR passage.
A GR valve mechanism, a variable swirl valve mechanism for changing a swirl in a cylinder by changing a passage area of an intake port of the engine, an exhaust turbine variable displacement mechanism according to an engine rotation speed and an engine load, and the E.
In a diesel engine control device that controls a GR valve mechanism and controls the variable swirl valve mechanism according to the engine speed, an engine speed detection means for detecting an engine speed, and an engine load detection for detecting an engine load Means, using at least the engine speed and the engine load as parameters, so that the capacity of the exhaust turbine decreases as the engine speed decreases and the engine load decreases, and the exhaust turbine increases as the engine speed increases and the engine load increases. The exhaust turbine variable displacement control map set to increase the displacement of the engine, and at least the engine speed and the engine load as parameters. The opening of the EGR valve increases as the engine speed decreases and the engine load decreases. And the higher the rotational speed and the higher the load the E An EGR valve control map for determining the EGR valve so that the opening of the GR valve is reduced; and a variable swirl valve mechanism in a high rotation region so as to close the variable swirl valve mechanism in a low rotation speed region using at least an engine rotation speed as a parameter. A variable swirl valve control map for deciding to open the swirl valve mechanism, a detection signal from the engine rotational speed detecting means and the engine load detecting means, the exhaust turbine variable displacement control map, the EGR valve control map, and the variable swirl The exhaust turbine variable displacement mechanism based on the valve control map;
A controller for controlling the GR valve mechanism and the variable swirl valve mechanism; the controller determines whether or not the engine is in an accelerating operation state based on an engine load detected by the engine load detecting means; When it is determined that the speed is in the low rotation region and the engine load is in the low load region, the exhaust turbine variable displacement mechanism is set to a value larger than the control value of the exhaust turbine variable displacement control map for a predetermined period. Control, the opening degree of the EGR valve mechanism is controlled at a value larger than the control value set on the EGR valve control map, and the variable swirl valve mechanism is set larger than the control value set on the map. A control device for a diesel engine, which is controlled by a value.