JPS61286568A - Exhaust gas recirculation controlling method for diesel engine - Google Patents

Abstract

PURPOSE:To aim at reduction in exhaust smoke and NOx content in exhaust gas, by performing an exhaust gas recirculation at a time when idling, where an automatic transmission is set to a running range, is in shortness and, when this idling keeps on doing longer, reducing an EGR quantity or stopping the exhaust gas recirculation. CONSTITUTION:At engine running, first an optimum exhaust gas EGR flow rate Qegr is determined according to the fuel injection quantity calculated separately and an engine speed at a control unit 25. Next, the release of operation on an accelerator pedal 19 is detected by an accelerator sensor 27, and at the time of such idling as being detected as a car speed is almost zero by a car speed sensor 29 as well as when an automatic transmission 14 is set to a driving range of a D range or the like from a shift range sensor 29, discrimination of whether the specified time elapsed since this running state has started or not is carried out. And, when YES is the case, the said EGR flow rate Qegr is multiplied by a compensation factor x (<1), compensating this Qegr for decrement. And, when NO is the case, a pulse signal in the duty ratio conformed to the Qegr is outputted to a suction pressure regulating valve 43.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to re-tl! exhaust gas from diesel engines used in vehicles such as automobiles. ! The present invention relates to an i-ring control method, and more particularly to an exhaust gas recirculation control method during idle operation of a diesel engine used in combination with an automatic transmission.

Conventional technology In diesel engines, it has already been proposed to recirculate the exhaust gas even during idling operation in order to reduce the NOx concentration in the exhaust gas.
It is shown in the publication No.-215955.

In a diesel engine used in combination with an automatic transmission, during idling operation, the shift range of the automatic transmission is set to a driving range such as D range, or is set to a neutral range (N range). The engine load changes depending on whether the shift range is in the driving range or not, and when the shift range is set to the driving range, the engine load increases compared to when the shift range is set to the neutral range. The amount of excess air in the engine combustion chamber decreases.

Therefore, if exhaust gas recirculation is performed at the same flow rate when the shift range is in the travel range and in the neutral range during idling operation, there is a risk that the amount of exhaust smoke will increase when the shift range is in the travel range. In view of this, when the shift range is set to the driving range, exhaust gas recirculation should be performed at a lower flow rate than when the shift range is set to the neutral range, or exhaust gas recirculation should be stopped. Patent application filed in 1983-249 by the same applicant as the applicant of the present application
It has already been proposed in No. 919.

Problems to be Solved by the Invention As mentioned above, during idling operation when the shift range of the automatic transmission is set to the travel range, the exhaust gas recirculation flow m is reduced or the exhaust gas recirculation is stopped. For example, the amount of exhaust smoke decreases by E1, but the amount of exhaust gas increases.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an improved exhaust gas recirculation control method for a diesel engine that combines the reduction of exhaust smoke with the reduction of NOx [1] in the exhaust gas.

Means for Solving the Problems According to the present invention, in a diesel engine gas recirculation control method used in combination with an automatic transmission, the shift range of the automatic transmission is changed. Exhaust gas is recirculated at a predetermined flow rate until a predetermined time period elapses after the idle operating state set in the driving range starts, and the idle operating state with the shift range of the automatic transmission set in the driving range starts. Exhaust gas from a diesel engine, characterized in that after a predetermined period of time has elapsed, the exhaust gas is recirculated at a lower flow m than before the predetermined time has elapsed, or the exhaust gas recirculation is stopped. This is accomplished by a recirculation control method.

Effects of the Invention According to the diesel engine of the exhaust gas recirculation υJtl11 method according to the present invention, if the idling state in which the shift range of the automatic transmission is set to the travel range continues for a long time, an increase in exhaust smoke can be avoided. The exhaust gas recirculation flow rate is reduced or the exhaust gas recirculation is stopped as much as possible, but if the automatic transmission's shift range is set to the driving range and the idling state cannot be maintained very well, the exhaust gas is recirculated at a predetermined flow rate. Gas recirculation is performed to reduce the Nox concentration of the exhaust gas.

EXAMPLES Below, the present invention will be explained in detail with reference to the accompanying drawings A-1.

FIG. 1 shows an embodiment of a vehicular diesel engine equipped with an exhaust gas IF circulation control device that implements the exhaust gas recirculation control method for a diesel engine according to the present invention. In the figure, 1 indicates a diesel engine, and
The piston 3 is slidably received in the cylinder bore 2, and a combustion chamber 4 is located above the piston 3.
It also has a swirl chamber 6 that communicates with the combustion chamber 4 through a nozzle 5, into which liquid fuel for a diesel engine is injected and supplied from a fuel injection nozzle 7. . The diesel engine 1 has an intake port 1 (not shown) that opens into a combustion chamber 4 and an exhaust boat 10.
An intake manifold 9 is connected to the intake boat, and an exhaust manifold 11 is connected to the exhaust boat 10.

The intake boat and the exhaust boat 10 are each opened and closed by a poppet valve 33.
Only the poppet valve for exhaust is shown.

The piston 3 is drivingly connected to the crankshaft 13 by a connecting pin 8. The crankshaft 13 is drivingly connected to an input member of the automatic transmission 1fi14.

Automatic shifting! fi14 is a hydraulic control device 1 that controls the switching of gears of the hydraulic torque converter 15, the gear transmission 16 including the planetary tooth Tt1 device, and the vA vehicle transmission 16.
7, the shift range is determined by the shift lever (shift range select lever) 18 operated by the driver's hand, the medium speed, and the amount of depression of the accelerator pedal 19. The settings can be switched between. The shift range of the automatic transmission 14 is N.
6 shift ranges: Range (neutral range), D range, 2 range, and L range, 3 forward ranges, R range (simulation range), and P range (parking range). The shift lever 18 is configured to selectively set one of the six shift ranges from shift 1 to range.

The fuel injection nozzle 7 is connected to a fuel injection pump 21 through a fuel conduit 20, and is supplied with liquid fuel at a predetermined pressure depending on the engine load from the fuel injection pump 21. The fuel injection pump 21 is
It is a well-known electrically controlled distribution type fuel injection pump that has a spill ring (not shown) driven by a linear solenoid 22 and adjusts the fuel injection amount according to the position of the spill ring. be. 3. Control of energization to the linear solenoid 22. This is performed by the IJ II device 25.

The exhaust manifold 11 has an exhaust gas intake boat 31, and the intake manifold 9 has an exhaust gas injection boat 32.
are provided respectively, and the exhaust gas intake boat 31 is
It is connected in communication to the exhaust gas injection boat 32 via a conduit 33, an exhaust gas recirculation control valve 34, and a conduit 35.

The IJI air gas ring control well 34 includes a valve element 37 for opening and closing a valve boat 36, which is connected by a valve rod 38 to a diaphragm device 39 and connected to a diaphragm device 39 by a diaphragm 40.
When a negative pressure greater than a predetermined value is not introduced into the diaphragm chamber 41 provided on one side of the valve boat 36, the valve boat 36 is pressed down by the spring force of the compression coil spring 42, and the valve boat 36 is closed.
On the other hand, when a negative pressure greater than a predetermined value is introduced into the diaphragm chamber 41, it is lifted against the spring force of the compression coil spring 42, and the valve boat 36 is opened according to the magnitude of the negative pressure. ing.

The diaphragm chamber 41 is connected to a negative pressure regulating valve 43 by a conduit 44.
The negative pressure regulating valve 43 has its input port connected to the negative pressure pump 23 by a conduit 45. The negative pressure regulating valve 43 is supplied with negative pressure from the negative pressure pump 23, regulates the negative pressure according to the current applied to the solenoid 46, and supplies the regulated negative pressure to the diaphragm chamber 41 via the conduit 44. It looks like this. Control of energization to the solenoid 46 is performed by the control device 25.

The control device 25 includes a microcomputer 50, as best shown in FIG. The microcomputer 50 includes an input board device 51, a random access memory (RAM) 52, and a read-only memory (ROM).
>53, central processing unit (CPU) 54,
It is a general type that changes the number of rotations from the rotation speed sensor 26 to the rotation speed of the machine i11, and the information about the amount of depression of the accelerator pedal 19 from the accelerator sensor 27. , the vehicle speed sensor 128 provides information regarding the vehicle speed, and the shift 1 range sensor 29 provides information regarding the shift range of the automatic transmission 14 to the input boat device 51, and these information are sent to the RAM 52 and CPU.
54 and stored in the ROM 53, output port device 55 outputs standard signals to drive circuits 56 and 57 of linear solenoid 22 and solenoid 46, respectively, in the manner described below. It is supposed to be done.

The CPU 54 determines whether or not the diesel engine 1 is idling according to the vehicle speed detected by the vehicle speed sensor 928 and the amount of accelerator pedal depression detected by the accelerator sensor 27, and determines whether or not the diesel engine 1 is idling. A predetermined control target rotation speed is compared with the engine rotation speed detected by the rotation speed sensor 26, and a fuel injection amount is calculated so that the idle rotation speed is maintained at a predetermined control target rotation speed. Outputs the fuel injection amount signal based on port 1-
The device 55 outputs fuel to the drive circuit 56, and during load operation other than idling, fuel is output according to the engine rotation speed detected by the rotation speed sensor 26 and the amount of depression of the accelerator pedal 19 detected by the accelerator sensor 27. Calculate the injection amount or read from the data memory of [<0M53,
A fuel injection amount signal based on this is outputted from the output boat device 55 to the drive circuit 56.

The drive circuit 56 includes a servo amplifier circuit, receives information regarding the actual position of the spill ring of the fuel injection pump 21 from the spill position sensor 30, and receives the fuel injection darkness signal from the microcomputer 50, that is, the υ control target. The spill position signal is compared with the spill position signal from the spill position hinge 29, and based on the comparison result, the current value of the N current applied to the linear solenoid 24 is controlled so that the actual spill ring position becomes the control target position. <1 so that

? applied to the linear solenoid 24 as described above? By controlling the current value of the li flow, the fuel injection pump 21
The position of the spill ring is feedback-controlled, and the idle rotation speed of the fuel injection pump 21 is maintained at a predetermined control target rotation speed during idling operation.
), the amount of fuel supplied to the fuel injection nozzle 7 is increased or decreased, and *fik of liquid fuel is supplied to the fuel injection nozzle 7 according to the amount of depression of the accelerator pedal 19 and the engine speed during load operation other than idling operation.

The ROM 53 stores the optimum exhaust gas recirculation flow (J3) according to the fuel injection m and the engine speed as a two-dimensional map with the fuel injection m and the engine speed as variables, and the CPU 54 determines the flow as described above. Fuel injection m and rotation speed sensor + J26
The exhaust gas recirculation flow rate corresponding to the two control variables based on the detected engine rotational speed is continuously outputted from the ROM 53, and the optimal flow rate is determined according to this data value or by interpolation calculation based on the data value. A pulse signal having a duty ratio corresponding to the exhaust gas recirculation flow rate is outputted from the output boat device 55 to the drive circuit 57.

The drive circuit 57 includes a D/A converter, converts a pulse signal with a duty ratio given by the microcomputer 50 into a current signal according to the duty ratio, and adjusts the current given to the solenoid 46 according to this current signal. The current value is set to l1IItl.

By controlling the current value of the current applied to the solenoid 46 as described above, the negative pressure applied to the diaphragm device 41 by the negative pressure regulating valve 43 is controlled according to the current control, and the exhaust gas is adjusted according to this negative pressure. Gas recirculation control valve 34
The opening of the valve ■ is controlled, and the exhaust gas recirculation flow rate is controlled.

Furthermore, exhaust gas recirculation according to the invention 1m ft1l liB
To implement the method, the CPU 54 determines whether the shift range of the automatic transmission 1114 is the N range or the P range during idling operation, and when the shift range is the N range or the P range, the CPU 54 determines whether the shift range of the automatic transmission 1114 is the N range or the P range. The drive device 57 is configured to perform exhaust gas recirculation at the exhaust gas recirculation flow rate.
A pulse signal with a predetermined duty ratio is output to the automatic transmission 14, and when the shift range of the automatic transmission 14 is a driving range other than the N range and the P range, such as the D range, the shift range is set to the idle range. A predetermined duty is set to the drive device 57 so that exhaust gas recirculation is performed at the optimal exhaust gas recirculation flow rate as in the N range or P range until a predetermined time has elapsed after the start of operation. The ratio pulse signal is output, but the idling state where the shift range is set to the driving range is (i4'
After a predetermined period of time (for example, several minutes) has elapsed since the engine was started, the exhaust gas recirculation is performed at a flow rate lower than the optimal exhaust gas recirculation flow rate during idle operation. A pulse signal of the ratio is output to the drive device 57.

FIG. 3 is a flowchart showing an example of the implementation procedure of the exhaust gas recirculation control method for a deep-pillar engine according to the present invention.

In step 1, the optimum exhaust gas recirculation flow fmQ(![]r is determined according to the fuel injection MI and the engine speed. After step 1, the process proceeds to step 2.

In step 2, it is determined whether or not the accelerator pedal 19 is released.

When the accelerator pedal 19 has been released, the process proceeds to step 3, whereas when the accelerator pedal 19 has been depressed, the process proceeds to step 5.

In step 3, it is determined whether the vehicle speed is approximately zero. When the vehicle speed is approximately zero, the process proceeds to step 4, whereas when the vehicle speed is approximately zero, the process proceeds to step 5.

Step 4 is during idling when one accelerator pedal is released and the vehicle speed is approximately zero. In step 4, it is determined whether the shift range of the automatic transmission 14 is the N range or the P range. A determination is made. When the shift range is N range or P range, proceed to step 5;
When the shift range is not in any range, that is, when the shift range is a driving range such as the D range, the process advances to step 6.

In step 5, flag F is converted to 0. After step 5, proceed to step 9. In step 6, the flag F is converted to 1 (1 is set).After step 6, proceed to step 7.

In step 7, a predetermined period of several minutes has elapsed since the flag F became 1, that is, from the start of the idling state in which the shift range of the automatic transmission 14 was set to the travel range. A determination is made as to whether or not this has been done. When the predetermined time has elapsed, the process proceeds to step 8, whereas when the predetermined time has not elapsed, the process proceeds to step 9.

In step 8, the optimum exhaust gas recirculation flow ff1Qe(lr determined in step 1 is multiplied by a correction coefficient χ.The correction coefficient χ is a value smaller than 1, so that Optimal exhaust gas recirculation flowffi Q ea
r is corrected for impairment.

In step 9, the optimal exhaust gas recirculation flow port QOQr
A pulse signal having a duty ratio corresponding to the output voltage is outputted to the drive device 57.

In the actual yfi4V/4 shown in FIG. 3, in step 3, it is determined whether the vehicle speed is approximately zero; As shown in FIG. 4, it may be determined whether the brake is on or not. In this case, as shown in FIG. 2, a brake switch 47 for detecting whether the brake is on or not may be provided.

FIG. 5 shows an embodiment of a vehicular diesel engine equipped with an exhaust gas recirculation control apparatus for implementing the exhaust gas recirculation control method for a diesel engine according to the present invention.

In FIG. 5, parts corresponding to those in FIG. 1 are designated by the same reference numerals as in FIG.

In the embodiment shown in FIG. 5, a negative pressure control valve 48 is provided in the middle of the conduit 44. The negative pressure control valve 48 has a boat a connected to the diaphragm v41 of the exhaust gas recirculation υ control valve 34 and an atmospheric pressure boat b opened to the atmosphere.
and a negative pressure boat C connected to the negative pressure output boat of the negative pressure regulating valve 43. When energized, boat A is connected to atmospheric pressure boat B, whereas when not energized, boat A is connected to negative pressure boat B. It is designed to be connected to pressure boat C. The energization to the negative pressure control valve 48 is controlled by the control device 25 according to a 70-diameter pulse as shown in FIG.

Next, an example of how to control the energization of the negative pressure control valve 48 will be described with reference to the flowchart shown in FIG.

In step 20, it is determined whether or not the accelerator pedal 19 is released.

When the accelerator pedal 19 is released, the process proceeds to step 21, whereas when the accelerator pedal 19 is depressed, the process proceeds to step 22.

In step 21, it is determined whether the vehicle speed is approximately zero. When the vehicle speed is almost zero, step 22
On the other hand, if the medium speed is not approximately zero, the process advances to step 23.

In step 22, it is determined whether the shift range of the automatic shift 1jl14 is the N range or the P range. When the shift range of the automatic shift i14 is the N range or the P range, the process proceeds to step 23, whereas when the shift range is neither the N range nor the P range, that is, when it is in the travel range, the process proceeds to step 24.

In step 23, flag F is converted to zero. After step 23, the process proceeds to step 26.

In step 24, flag F is converted to 1. After step 24, the process proceeds to step 25.

In step 25, after flag F becomes 1,
That is, it is determined whether a predetermined period of time has elapsed since the shift range entered the idle operating state, which is the travel range. If the predetermined time has elapsed, the process proceeds to step 27, whereas if the predetermined time has not elapsed, the process proceeds to step 26.

In step 26, power supply to the negative pressure control valve 48 is stopped. At this time, by connecting the boat a of the negative pressure control valve 48 to the negative pressure boat C, the negative pressure regulated by the negative pressure regulating valve 43 is supplied to the die X flamm chamber 41 of the exhaust gas recirculation control valve 34. , exhaust gas recirculation is performed according to a predetermined principle.

In step 27, the negative pressure control valve 48 is energized. At this time, the boat a of the negative pressure control valve 48 is connected to the atmospheric pressure boat b instead of the negative pressure boat C, and atmospheric pressure is introduced into the diaphragm chamber 41 of the exhaust gas recirculation control valve 34. Therefore, at this time, the exhaust gas recirculation control valve 34 is closed and exhaust gas recirculation is stopped.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto.
It will be apparent to those skilled in the art that various other embodiments are possible within the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of a vehicular diesel engine equipped with an exhaust gas recirculation control device that implements the exhaust gas recirculation control method according to the present invention, and FIG. A block diagram showing one embodiment of a control device that performs fuel injection m control and exhaust gas recirculation control of a diesel engine, and FIGS. 3 and 4 respectively show the control steps of the exhaust gas recirculation control method according to the present invention. FIG. 5 is a flowchart showing another embodiment of a vehicle diesel engine equipped with an exhaust gas recirculation control device that implements the exhaust gas recirculation control method according to the present invention; FIG. 1 is a flowchart showing the control steps of the exhaust gas recirculation control method according to the present invention. 1...Diesel engine, 2...Cylinder bore, 3.
... Piston, 4... Combustion chamber, 5... Injection 0.6...
- Vortex chamber. 7...Fuel injection nozzle, 8...Connecting rod. 9...Intake manifold, 10...Exhaust boat, 1
1...Exhaust manifold, 12...Poppet valve, 1
3... Crankshaft, 14... Automatic transmission, 15...
・Hydraulic torque converter, 16...gear transmission,
17... Hydraulic control device, 18... Shift lever 21
9... Accelerator pedal, 20... Conduit, 21...
fuel injection pump. 22...Linear solenoid, 25...tIIIt!
Il device, 26... Rotation speed sensor, 27... Accelerator sensor, 28... Vehicle speed sensor, 29... Shift range sensor, 30... Spill position sensor, 31...
・Exhaust gas intake boat. 32... Exhaust gas injection bow 1~, 33... Conduit, 3
4... Exhaust gas recirculation control valve, 35... Conduit, 36
...Valve port, 37...Valve element, 38...Valve rod, 39...Diaphragm device, 40...Die X7
Fram, 41...Diaphragm chamber, 42...Compression coil spring, 43...Negative pressure regulating valve, 44.45...Conduit, 46...Solenoid. 47... Brake switch, 48... Negative pressure control plate valve,
50... Microcomputer, 51... Input boat device, 52... Random access memory, 53...
・Limited memory, 54...Central processing unit,
55...Output boat device, 56.57...Drive circuit Applicant Toyota Motor Corporation representative
Rihito Bentoki Masaki AkashiFigure 3Figure 4

Claims (1)

[Claims] In an exhaust gas recirculation control method for a diesel engine that is used in combination with an automatic transmission, the shift range of the automatic transmission is set to the travel range and the idling state starts until a predetermined period of time elapses. Exhaust gas is recirculated at a predetermined flow rate, and after a predetermined period of time has elapsed from the start of an idling state in which the shift range of the automatic transmission is set to the travel range, the flow rate is less than before the elapse of a predetermined period of time. 1. A method for controlling exhaust gas recirculation of a diesel engine, characterized by performing exhaust gas recirculation at a certain flow rate or stopping exhaust gas recirculation.