JP2000008965A - Control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a smoke amount generated at the quick acceleration time, even if the response of a throttle valve and EGR valve is delayed. SOLUTION: This engine 1 is provided with a throttle valve 7 for regulating the intake air amount passing an intake pipe 5, a throttle actuator 8 for regulating the opening of the throttle valve 7, EGR valve 15 arranged to EGR passage 13 for re-circulating one part of an exhaust to the intake pipe 5 and for regulating EGR gas amount and EGR actuator 16 for regulating the opening of EGR valve 15. The sectional area of the intake pipe 5 is bigger than the necessary sectional area for not producing a pressure loss in the intake pipe 5. When ECU 20 detects that the engine 1 operation is in the quick acceleration state, the drive of the throttle actuator 8 is controlled so as to operate the throttle valve 7 in a full open position and also the drive of EGR actuator 16 is controlled so as to operate EGR valve 15 to a closing side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine having a throttle valve for adjusting an amount of intake air and an exhaust gas recirculation device (EGR device) for returning a part of exhaust gas to an intake pipe. The present invention relates to a control device for a diesel engine for appropriately controlling an EGR rate, which is a ratio between a circulation amount (EGR gas amount) and an intake amount.

[0002]

2. Description of the Related Art In a diesel engine, there is conventionally known a technique in which a throttle valve is provided in the middle of an intake passage, and the throttle valve performs an intake throttle to reduce noise and vibration (Japanese Patent Laid-Open No. 61-16238). Gazette). Also,
In order to reduce NOx (nitrogen oxides) in exhaust gas, it is also known that exhaust gas recirculation in which part of exhaust gas is recirculated to an intake pipe as recirculated gas (EGR gas) is effective. To perform a large amount of exhaust gas recirculation at times,
The throttle valve is throttled to increase the intake pipe negative pressure.

[0003]

However, in the above prior art, the opening and closing of the throttle valve and the EGR valve (reflux control valve) for adjusting the amount of EGR gas are controlled using, for example, a diaphragm-driven actuator. You. In this case, when the actuator is driven in response to a command signal from a microcomputer or the like, the response of the throttle valve or the EGR valve is delayed, and the
The problem arises that the rate cannot be properly controlled.

Specifically, when the vehicle is rapidly accelerated from a state in which the intake throttle is activated (throttle valve is throttled) during low load operation, the throttle valve is controlled to open and the EGR valve is closed. Side controlled. At this time, the increase in the fresh air amount and the decrease in the EGR gas amount become slow due to the response delay of the throttle valve and the EGR valve described above. Therefore, the amount of fresh air becomes insufficient and the amount of EGR gas becomes excessive. As a result, it takes time for the EGR rate to decrease to a predetermined target value, and a large amount of smoke is generated temporarily.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problem, and has as its object to reduce the amount of smoke generated at the time of rapid acceleration even if there is a response delay of a throttle valve or an EGR valve. It is to provide a diesel engine control device that can.

[0006]

According to the present invention, there is provided a throttle valve for adjusting an amount of intake air passing through an intake pipe, a throttle actuator for adjusting an opening of the throttle valve,
A recirculation control valve disposed in a recirculation passage for recirculating a part of the exhaust gas to the intake pipe to adjust a recirculation amount of the exhaust gas; and a recirculation control actuator adjusting an opening degree of the recirculation control valve. It is assumed that the present invention is applied to a diesel engine in which a cross-sectional area of the intake pipe is larger than a required cross-sectional area for preventing a pressure loss from occurring in the intake pipe.

According to the first aspect of the present invention, there is provided a rapid acceleration detecting means for detecting that the operation of the engine is in a rapid acceleration state.
Acceleration control means for controlling the driving of the throttle actuator to operate the throttle valve to the fully open position and controlling the driving of the recirculation control actuator to operate the recirculation control valve to the closed side.

[0008] In short, in the diesel engine according to the present invention, the cross-sectional area of the intake pipe is made larger than the cross-sectional area required for preventing pressure loss in the intake pipe. More specifically, as described in claim 2, the cross-sectional area of the intake pipe is set to about 1.1 to 1.5 with respect to the required cross-sectional area of the intake pipe determined by the displacement of the engine and the maximum rotation speed. And double.

Therefore, when the throttle valve is controlled to the fully open position during rapid acceleration, a large amount of fresh air is supplied to the engine combustion chamber through the inside of the expanded intake pipe as described above. At this time, the EGR rate falls promptly in response to the sudden acceleration request. As a result, the throttle valve and the recirculation control valve (E
Even if there is a response delay of the GR valve, the amount of smoke generated at the time of sudden acceleration can be reduced.

According to the third aspect of the present invention, the recirculation passage is applied to a diesel engine which is opened downstream of the throttle valve. The throttle opening is controlled by the minimum opening in a region where the intake throttle does not occur.

That is, by controlling the throttle opening so that the intake throttle does not occur, the pressure loss generated in the intake pipe is reduced. Also, by controlling the throttle opening with the minimum opening in the region where the intake throttle does not occur, intake air flows toward the center of the intake pipe downstream of the throttle valve, and mixing of fresh air and recirculated gas is achieved. Be improved. By improving the mixing of fresh air and recirculated gas, uniform intake air is formed, and when applied to a multi-cylinder engine, variations in gas concentration between cylinders are eliminated.

[0012] In the invention described in claim 4, the recirculation passage is applied to a diesel engine that opens downstream of the throttle valve, and after the acceleration control means controls the throttle valve to be fully opened, a response by the recirculation control actuator is performed. At the time when the delay time has elapsed, the throttle opening is switched to the minimum opening in a region where the intake throttle does not occur.

When the EGR rate is lowered due to rapid acceleration, the throttle valve is initially controlled at the fully open position as described above.
When the GR rate reaches the target value, the throttle valve is controlled on the closed side of the fully open position. In this case, by switching the throttle opening from the fully open state to the minimum opening in a region where the intake throttle does not occur, the amount of smoke generated immediately after rapid acceleration is reduced, the pressure loss in the intake pipe is reduced, and the fresh air is reduced. The mixing with the recirculated gas can be improved.

According to the fifth aspect of the invention, as the engine speed increases, the minimum opening of the throttle valve in a region where the intake throttle does not occur is increased. In this case, it is possible to always reduce the pressure loss in the intake pipe and to improve the mixing of the fresh air and the recirculated gas irrespective of the change in the engine speed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The vehicle diesel engine according to the present embodiment includes an exhaust gas recirculation device (EGR device) for returning a part of the exhaust gas to the intake pipe,
The exhaust gas recirculation amount (EGR gas amount) is controlled according to the engine operating state. Especially during low load operation of the engine,
The EGR gas amount is controlled so that the maximum EGR rate is obtained.

1 and 2 show an outline of an engine control device according to the present embodiment. FIG. 1 is a front view of the engine as viewed from the front, and FIG. 2 is a plan view of the engine as viewed from above. It is.

As shown in FIGS. 1 and 2, the engine 1
Is composed of a four-cylinder diesel engine having four cylinders # 1 to # 4. An intake manifold 3 is connected to the intake side, and an exhaust manifold 4 is connected to the exhaust side. An intake pipe 5 is connected to the intake manifold 3, and fresh air that has passed through the air cleaner 6 is introduced into the intake pipe 5 from the most upstream portion thereof. The intake pipe 5 is provided with a throttle valve 7 as an intake throttle valve with a variable opening. The throttle valve 7 has a main shaft 7a connected to a diaphragm-driven throttle actuator 8.

In the throttle actuator 8, the negative pressure control valve 9 is constituted by a known electromagnetic control valve.
(Electronic control device) A negative pressure acting on the diaphragm chamber 11 from the vacuum pump 10 is controlled in accordance with a signal from the electronic control unit 20. That is, when the negative pressure of the diaphragm chamber 11 changes with the driving of the negative pressure control valve 9, the diaphragm 12 is displaced in accordance with the negative pressure, the main shaft 7a rotates, and the throttle valve 7
Is adjusted. At this time, the amount of intake air passing through the intake pipe 5 is adjusted according to the opening degree of the throttle valve 7.

An EGR passage 13 is provided between the downstream side of the throttle valve 7 and the exhaust manifold 4.
An opening 14 of the EGR passage 13 is provided on the intake pipe wall surface. A part of the exhaust gas is recirculated to the intake pipe 5 downstream of the throttle by the EGR passage 13. An EGR for opening and closing the opening 14 of the EGR passage 13 is provided in the intake pipe 5.
A valve 15 is provided, and the opening degree of the EGR valve 15 (the opening 1
4 is adjusted by a diaphragm drive type EGR actuator 16.

In the EGR actuator 16, the negative pressure control valve 17 is constituted by a known electromagnetic control valve.
The negative pressure acting on the diaphragm chamber 18 from the vacuum pump 10 is controlled in accordance with the signal from the vacuum pump 20. That is,
When the negative pressure in the diaphragm chamber 18 changes with the driving of the negative pressure control valve 17, the diaphragm 19 is displaced in accordance with the negative pressure, and the opening (lift amount) of the EGR valve 15 is adjusted. At this time, the EGR gas amount is adjusted according to the opening of the EGR valve 15.

The ECU 20 has a well-known CPU, ROM, R
The microcomputer mainly includes a microcomputer having an AM and the like, and controls the driving of the throttle actuator 8 and the EGR actuator 16 by obtaining information such as the engine speed Ne and the accelerator opening ACCP. The ECU 20
Calculates a fuel injection amount and a fuel injection timing based on operation information such as an engine speed Ne and an accelerator opening ACCP, and controls a fuel injection pump (not shown) according to the fuel injection amount and the fuel injection timing.

FIG. 3 shows the throttle valve 7 and the EGR valve 1.
FIG. 5 is an enlarged cross-sectional view showing the configuration of an intake mechanism mainly including 5. The intake pipe 5 has a circular passage in the pipe, and its cross-sectional area is indicated by “S”. Here, in the present embodiment, the cross-sectional area S is defined as follows so that a larger amount of fresh air passes through the throttle valve 7 and is sent downstream thereof.

That is, as shown in FIG. 4, in the region where the cross-sectional area of the intake pipe (mm ^ 2) is equal to or less than "S1", the intake air amount (liter / min) at the maximum rotation is small, and the engine displacement is reduced. Required amount (displacement ×
(Maximum rotational speed / 2). In this case, even when the throttle is fully opened, the intake air is throttled in the intake pipe, and a sufficient intake air amount cannot be obtained. That is, only an intake air amount equal to or less than the stroke volume of the piston of the engine 1 is obtained, and the sectional area of the intake pipe becomes insufficient, resulting in a pressure loss in the intake pipe. Conversely, "S
Even if the cross-sectional area of the intake pipe is larger than "1", the intake air amount reaches a plateau because it cannot be taken in beyond the stroke volume of the piston. Therefore, in the conventional engine, the S1 in FIG.
The design of the intake pipe cross-section was designed.

On the other hand, in this embodiment, the required amount (displacement amount × discharge amount) determined by the engine displacement and the maximum engine speed is determined.
The intake pipe cross-sectional area is increased so that a larger amount of intake air can be obtained than the maximum rotation speed / 2). Specifically, the cross-sectional area of the intake pipe is set to “S2” which is about 1.2 times the “S1”.

Next, the operation of the control device will be described. FIG. 5 is a time chart for explaining the operation in the present embodiment, and FIG. 5 shows an operation when the vehicle is rapidly accelerated from a low load operation. In FIG. 5, the two-dot chain line represents the behavior of the conventional device, and the solid line represents the behavior of the device of the present invention. However, those which operate in the same way in the conventional and the present invention are shown only by solid lines.

Before time t1, the operation amount of the accelerator pedal is relatively small (the accelerator opening is relatively small), and the engine 1 is operated at a low load. At this time, by reducing the throttle valve 7 and maximizing the lift amount of the EGR valve 15, the intake pipe negative pressure is increased and a large amount of EGR is performed. Comparing the throttle opening at the same fresh air volume between the present invention and the conventional one, as described above, the present invention has a larger intake pipe cross-sectional area (intake passage area) than the conventional one. The degree is getting smaller.

Thereafter, at time t1, the accelerator pedal is depressed for rapid acceleration. Then, the fuel injection amount is increased following the change in the accelerator opening. However, if the fuel injection amount is suddenly changed in accordance with the sudden change in the accelerator opening, drivability may be deteriorated. Therefore, the fuel injection amount changes while being moderated with respect to the change in the accelerator opening.

When the fuel injection amount is increased, the throttle opening (deg) is controlled to the open side, and the throttle valve 7 is rotated to the fully open position. During the operation of the throttle valve 7, the throttle valve 7 is moved to the target position (fully open position) at time t2 due to a response delay of the throttle actuator 8.
To reach. Here, “Ta” in the figure corresponds to the response delay time of the throttle actuator 8. Although the fresh air volume increases with an increase in the throttle opening, comparing this model with the conventional model, the new air volume increases at a higher rate and the new air volume when the throttle is fully open due to the difference in the intake pipe cross-sectional area. Increase.

After time t1, the EGR valve 15 is controlled to be closed, and the EGR gas amount decreases in accordance with the decrease in the EGR valve lift amount. When the EGR valve 15 operates, the EGR
Due to the response delay of the actuator 16, EG at time t3
The R valve lift reaches the target value. Here, “T” in FIG.
“b” corresponds to the response delay time of the EGR actuator 16.

Further, after time t1, the amount of fresh air increases and the amount of EGR gas decreases, so that the EGR rate decreases. In the case of the conventional device, the increase in the fresh air amount is slow and the increase amount is relatively small, so that the time required for decreasing the EGR rate is long. Therefore, the EGR gas becomes excessive, and a peak appears in the smoke emission amount. That is, a large amount of smoke is temporarily generated.

On the other hand, in the case of the present invention, the amount of fresh air increases rapidly and the amount of increase is relatively large. Therefore, even if the amount of EGR gas decreases as in the prior art, that is, the response delay of the EGR actuator 16 Even if the time Tb exists, the EGR rate decreases quickly. As a result, the degree of excessive EGR is reduced, and peak smoke is eliminated.

After the EGR valve lift reaches the target value (after time t3), the throttle opening of the conventional device is kept as it is (fully opened), whereas the throttle opening of the present invention is not changed. Only the fixed amount is controlled to close. By the close side control of the throttle opening, the fresh air amount after time t3 converges to a predetermined value.

From time t3 onward, the value at which the throttle opening is held may be the minimum opening in a region where the throttle valve 7 does not cause an intake throttle. In this case, a stable intake operation without pressure loss can be obtained by not causing an intake throttle. Further, by controlling the throttle valve 7 to the closed side with respect to the fully open position, a forward flow region and a reverse flow region of the intake air are formed in the intake pipe 5, and the fresh air and the EGR gas are efficiently produced by such a flow region distribution. Mixes well.

Here, the flow of intake air in the intake pipe 5 when the throttle valve 7 is throttled will be described. When the throttle is fully opened, the intake air flows downstream of the throttle valve 7 in parallel with the intake pipe wall. On the other hand, when the throttle valve 7 is throttled,
As shown in FIG. 6, a forward flow region from upstream to downstream and a reverse flow region from downstream to upstream appear, and in the forward flow region, the intake air flows from near the wall surface of the intake pipe 5 toward the center. Flows. In this case, the opening 1 of the EGR passage
By flowing the EGR gas from 4 into the forward flow region, the EGR gas is diffused to the central portion along with the flow of the intake air, and is efficiently mixed with fresh air.

That is, when the throttle valve 7 is controlled to the fully open position as shown in FIG. 7B, the EGR gas is intensively distributed in the lower portion of the intake pipe, but as shown in FIG. Is controlled to the closed side (for example, the throttle angle α =
EGR gas is distributed throughout the intake pipe.

FIG. 8 shows the concentration distribution of the EGR gas in the cross section of the intake pipe, and FIGS.
This corresponds to (a) and (b). In FIG. 8B, a large difference in the concentration of EGR gas appears in the intake pipe.
In (a), the density difference is relatively small. this is,
This is considered to be because the EGR gas is sufficiently stirred in the forward flow region and the reverse flow region of the intake air. From the above, it can be seen that the mixing of fresh air and EGR gas is improved in the state of FIG. The gas distribution states shown in FIGS. 7 and 8 have been confirmed by a well-known visualization test performed under the conditions of a constant EGR rate and a constant engine speed.

FIG. 9 is a flowchart showing a throttle control procedure for realizing the operation of FIG. 5 described above. This process is executed by the ECU 20 at predetermined time intervals (for example, every 4 ms).

In FIG. 9, the ECU 20 first reads the engine speed Ne and the fuel injection amount Q in step 101, and then calculates the target throttle opening (deg) in step 102 according to, for example, the map of FIG. In the map of FIG. 10, in a low load region (Q <Q1 region), the target throttle opening is set at “θ1”, which is relatively small so that a large amount of EGR can be realized. In the area (Q1), the target throttle opening is set at “θ2”, which is relatively large.

However, in the middle to high load range, the target throttle opening degree =
When θ2 is set, as shown in FIG. 11, the target throttle opening is set according to the engine speed Ne at that time. FIG. 11 defines the minimum value of the throttle opening at which the intake throttle does not occur. When the target throttle opening is set on the characteristic line L in FIG. The pressure loss due to the intake throttle is reduced while mixing with gas is improved.

Thereafter, the ECU 20 determines whether or not the acceleration control flag F is "0" at step 103.
Here, F = 1 indicates that the vehicle is undergoing rapid acceleration based on accelerator operation or the like, and F = 0 indicates that it is not during rapid acceleration. F =
If it is 0, the ECU 20 proceeds to step 104, and determines whether or not it is during rapid acceleration based on the engine operation information.
For example, if the change amount ΔQ of the fuel injection amount or the change amount ΔACCP of the accelerator opening is equal to or larger than a predetermined value, it is determined that the vehicle is undergoing rapid acceleration.

If not during rapid acceleration (step 104 is N
In the case of O), the ECU 20 proceeds to step 105 and controls the throttle actuator 8 using the calculated target throttle opening as a command value. After that, the process of this routine is temporarily ended. In this case, the throttle opening is controlled by "θ1" in FIG. 10 during low load operation, and the throttle opening is controlled by "θ2" in FIG. 10 during other operation.

When the vehicle is suddenly accelerated (when step 104 is YES), the ECU 20 performs acceleration control after step 106. That is, the ECU 20 sets the acceleration control flag F to “1” in step 106.
For example, at time t1 in FIG. 5, the flag F is changed from “0” to “1”.

Further, the ECU 20 determines whether or not the response delay time Tb of the EGR actuator 16 has elapsed after the start of the acceleration control accompanying the rapid acceleration in step 107. The response delay time Tb may be set in advance as a fixed value specific to the apparatus, but may be variably set in accordance with the engine load (fuel injection amount Q or accelerator opening ACCP) using, for example, the relationship of FIG. You may.

Immediately after it is determined that sudden acceleration has occurred,
Step 107 because the response delay time Tb has not yet elapsed.
Is negative, the ECU 20 sets the target throttle opening to the "fully open position" in step 108. Then, the throttle actuator 8 is controlled using the fully opened position as a command value, and then the processing of this routine is terminated. For example, at times t1 to t3 in FIG. 5, the throttle opening is controlled to the fully open position. Note that, at time t1 to t3, since F = 1, steps 101 → 102 → 1
The processing is executed in the order of 03 → 107 →.

When the response delay time Tb has elapsed (YES in step 107), the ECU 20 proceeds to step 109 and clears the acceleration control flag F to "0". Also,
The ECU 20 controls the throttle actuator 8 using the target throttle opening as a command value in the following step 110, and thereafter temporarily terminates the processing of this routine. In FIG. 5, step 107 is affirmatively determined at time t3.

After time t3 in FIG. 5, “θ” in FIG.
2 "controls the throttle opening. In this case, using the relationship of FIG. 11, the throttle opening is controlled to the close side to the extent that the intake throttle does not occur.

FIG. 13 is a flow chart showing an EGR control procedure. This processing is executed every predetermined time by the ECU 20.
Is executed by In FIG. 13, first, in step 201, the ECU 20 determines the engine speed Ne and the fuel injection amount Q
Is read, and in the subsequent step 202, the target EGR rate is calculated according to, for example, the map of FIG. In FIG. 14, basically, the target EGR rate at the time of low rotation and low load is large, and the target EG rate increases with the increase of the engine speed Ne or the fuel injection amount Q.
The R rate decreases. The maximum value of the target EGR rate is defined by structural restrictions.

Thereafter, the ECU 20 obtains the EGR valve lift amount corresponding to the target EGR rate in step 203, controls the EGR actuator 16 using the lift amount as a command value, and thereafter terminates the processing of this routine once.

According to the above-described embodiment, the following effects can be obtained. (A) In the diesel engine 1 according to the present embodiment,
The cross-sectional area of the intake pipe 5 was made larger than a necessary cross-sectional area for preventing pressure loss in the intake pipe 5. Specifically, the cross-sectional area of the intake pipe was set to about 1.2 times the required cross-sectional area of the intake pipe (S1 in FIG. 4) determined from the displacement of the engine and the maximum rotation speed. Then, at the time of rapid acceleration, the drive of the throttle actuator 8 was controlled so as to operate the throttle valve 7 to the fully open position, and the drive of the EGR actuator 16 was controlled so as to operate the EGR valve 15 to the closed side. In such a case, the amount of smoke generated at the time of rapid acceleration can be reduced even if the EGR rate falls promptly in response to the request for rapid acceleration and the response delay of the throttle valve 7 or the EGR valve 15 occurs.

(B) As the actuators 8 and 16 for opening and closing the throttle valve 7 and the EGR valve 15, existing ones can be used, and an expensive actuator with good responsiveness is not required. Therefore, in realizing the present embodiment, no increase in cost is induced.

(C) After the throttle valve 7 is fully opened during rapid acceleration, when the response delay time Tb by the EGR actuator 16 elapses, the throttle opening is switched to the minimum opening in a region where the intake throttle does not occur. I did it.
In this case, the mixing of fresh air and EGR gas is improved while the pressure loss generated in the intake pipe 5 is reduced. When the mixing of the fresh air and the EGR gas is improved, uniform intake air is formed, and the variation in the gas concentration between the cylinders is eliminated.

(D) As the engine speed Ne increases,
The minimum opening of the throttle valve 7 in the region where the intake throttle does not occur is increased. In this case, reduction of pressure loss in the intake pipe 5 and improvement of mixing of fresh air and EGR gas can be always realized irrespective of a change in the engine speed Ne.

The embodiment of the present invention can be embodied in the following forms other than the above. In the above embodiment, the cross-sectional area of the intake pipe is set to be about 1.2 times the required cross-sectional area of the intake pipe (S1 in FIG. 4) determined from the engine displacement and the maximum rotation speed. change. The appropriate value of the intake pipe cross-sectional area is about 1.1 to 1.5 times the required cross-sectional area of the intake pipe determined by the displacement of the engine and the maximum number of revolutions. If there is no restriction, the intake pipe cross-sectional area may be increased to about 1.5 times the required cross-sectional area (S1 in FIG. 4) to ensure a sufficient fresh air volume when the throttle is fully opened.

In the above embodiment, the minimum opening (target throttle opening θ2) in a region where the intake throttle does not occur is set using the relationship of FIG. 11 except when the engine is under low load operation. The throttle opening at that time may be given as a fixed value. In addition, the throttle opening is controlled by the minimum opening in a region where the intake throttle does not occur, whereby fresh air and E
A series of components for improving mixing with the GR gas may be omitted. In such a case, although the effect of improving the mixing between fresh air and EGR gas cannot be obtained, the gist of the present invention such as reducing the amount of smoke generated at the time of sudden acceleration is still satisfied.

When the throttle actuator 8 and the EGR actuator 16 are embodied, a negative pressure diaphragm type actuator is used, but these configurations are changed.
For example, various actuators may be configured using a stepping motor, a linear motor, and a linear solenoid,
Even in such a case, the above-described excellent effects can be obtained.

Although the opening 14 of the EGR passage 13 is provided in the wall of the intake pipe, the opening 14 may be provided near the center of the intake pipe 5. In this case as well, by adjusting the throttle opening as described above, the mixing of fresh air and EGR gas is improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of an engine control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an outline of an engine control device.

FIG. 3 is an enlarged cross-sectional view illustrating a configuration of an intake mechanism.

FIG. 4 is a diagram showing a relationship between an intake pipe cross-sectional area and an intake air amount at the time of maximum rotation.

FIG. 5 is a time chart for explaining an operation in the embodiment.

FIG. 6 is a sectional view showing a forward flow region and a reverse flow region of intake air in an intake pipe.

FIG. 7 is a sectional view showing a distribution state of EGR gas in the intake pipe.

FIG. 8 is a view showing a concentration distribution of EGR gas in a cross section of the intake pipe.

FIG. 9 is a flowchart showing a throttle control procedure.

FIG. 10 is a map for setting a target throttle opening.

FIG. 11 is a map for setting a target throttle opening.

FIG. 12 is a diagram showing a relationship between an engine load and a response delay time Tb of an EGR actuator.

FIG. 13 is a flowchart showing an EGR control procedure.

FIG. 14 is a map for setting a target EGR rate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 5 ... Intake pipe, 7 ... Throttle valve, 8 ... Throttle actuator, 13 ... EGR passage as recirculation passage, 14 ... Opening, 15 ... EGR valve as recirculation control valve, 16 ... Recirculation control actuator ECU (Electronic Control Unit) constituting rapid acceleration detecting means and acceleration control means.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 41/10 360 F02D 41/10 360 43/00 301 43/00 301K 301R F-term (reference) 3G062 AA01 BA06 CA04 DA02 EA08 EB15 FA13 GA01 GA04 GA06 3G065 AA01 CA12 DA02 EA04 FA03 FA11 GA05 GA10 GA46 3G084 AA01 BA05 BA20 CA04 DA10 EB12 EC03 FA07 FA10 FA33 3G092 AA02 AA17 AB03 DC01 DC09 DG07 EA01 EA02 EC01 FA15 GA12 HA01Z13 HA03 LB13 LC07 MA15 ND02 NE02 NE07 NE23 PA01Z PA11A PD15A PE01Z PF03Z

Claims (5)

[Claims] A throttle valve for adjusting an amount of intake air passing through an intake pipe; a throttle actuator for adjusting an opening of the throttle valve; and a recirculation passage for recirculating a part of exhaust gas to the intake pipe. A recirculation control valve arranged to adjust a recirculation amount of the exhaust gas, and a recirculation control actuator for adjusting an opening degree of the recirculation control valve, wherein a cross-sectional area of the intake pipe is reduced by a pressure loss in the intake pipe. The present invention is applied to a diesel engine having a larger cross-sectional area than a required cross-sectional area for preventing the occurrence of a rapid acceleration, and a rapid acceleration detecting means for detecting that the operation of the engine is in a rapid acceleration state; While controlling the drive of the throttle actuator to operate the throttle valve to the fully open position, the drive of the recirculation control actuator is operated to operate the recirculation control valve to the closed side. Control device for a diesel engine, characterized in that it comprises a acceleration control means Gosuru. 2. The intake pipe according to claim 1, wherein a cross-sectional area of the intake pipe is about 1.1 to 1.5 times a required cross-sectional area of the intake pipe determined by an engine displacement and a maximum rotation speed. Control unit for diesel engine. 3. The method according to claim 1, wherein the recirculation passage is applied to a diesel engine that is opened downstream of the throttle valve, and in a region where the intake throttle is not generated except when the throttle valve performs the throttle operation during a low-load operation of the diesel engine. The diesel engine control device according to claim 1 or 2, wherein the throttle opening is controlled at the minimum opening. 4. The method according to claim 1, wherein the recirculation passage is applied to a diesel engine that is opened downstream of the throttle valve, and after a response delay time by a recirculation control actuator elapses after the throttle valve is fully opened by the acceleration control means. 3. The diesel engine control device according to claim 1, wherein the throttle opening is switched to a minimum opening in a region where the intake throttle does not occur. 5. The control device according to claim 3, wherein the minimum opening of the throttle valve in a region where the intake throttle does not occur increases as the engine speed increases.