JPS60128966A - Recirculation controlling method of exhaust gas in diesel engine - Google Patents

Abstract

PURPOSE:To improve a suction intercepting effect in time of engine operation, by performing engine retardation upon opening an EGR valve at idling, while making the said valve too so as to be closed in time of operation stoppage, in case of a device having a suction intercept valve which is closed in time of stoppage in the engine operation. CONSTITUTION:In time of a key switch 27 being closed, an OFF signal is outputted to each of solenoid valves 21 and 22 by means of a control unit 25 when cooling water temperature to be detected at a water temperature sensor 28 is below the setting value, but when the cooling water temperature is above the setting value, an ON signal is outputted to the solenoid valve 22 alone. On the other hand, the ON signal is outputted to each of these solenoid valves 21 and 22 till the specified period elapses by that point that the key switch 27 is closed in time of engine stoppage. And, an auxiliary suction control valve 16 is set to a full-open position in time of warming-up via a diaphragm device 18 but after the warming-up is all over, it is set to a half-open position, and in time of the key switch 27 being opened, it is set to a full-close position, respectively. Moreover, also as for an EGR valve 34, it is controlled to be opened in time of idling, while in time of the key switch 27 being opened, it is made so as to be fully closed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an exhaust gas recirculation control method for a diesel engine used in a vehicle such as an automobile. The present invention relates to an exhaust gas recirculation control method for a diesel engine, in which an intake passage is closed by an intake cutoff valve when the intake air supply is performed.

Background of the Invention In diesel engines used in vehicles such as automobiles,
During load changes, the exhaust gas recirculation control valve is opened even during idling to recirculate the exhaust gas, reducing the amount of NO in the exhaust gas emitted from the diesel engine even during idling.
It has been proposed to reduce the x concentration.

If the exhaust gas recirculation control valve is open and exhaust gas recirculation occurs even during idle operation, the exhaust gas recirculation control valve is open and exhaust gas recirculation occurs when the key switch is opened and diesel engine operation is stopped. Exhaust gas flows into the intake passage until the diesel engine completely stops operating, so even if the intake passage is blocked by the intake cutoff valve when the key switch is opened to stop the diesel engine, the exhaust gas will not be exhausted to the engine combustion chamber. Due to the flow of gas, the intake shutoff effect by the intake shutoff valve is reduced, and the diesel engine is no longer stopped quickly without causing large vibrations.

OBJECTS OF THE INVENTION The present invention provides a system for preventing exhaust gas recirculation from occurring when the intake cutoff valve closes the intake passage when the diesel engine is stopped, even if exhaust gas recirculation occurs during idling operation. It is an object of the present invention to provide an improved exhaust gas recirculation control method for a diesel engine so that the intake air blocking effect of the present invention effectively works to stop the operation of the diesel engine.

DESCRIPTION OF THE INVENTION According to the present invention, an exhaust gas recirculation control method for a diesel engine in which the intake passage is blocked by an intake cutoff valve when a key switch is opened to stop operation is provided. , an exhaust gas recirculation control method in which the exhaust gas recirculation control valve is opened during idle operation to perform exhaust gas recirculation, and when the operation is stopped, the exhaust gas recirculation control valve is closed in response to the opening of the key switch. achieved by

Effects of the Invention According to the exhaust gas recirculation control method for a diesel engine according to the present invention, when the key switch is opened, the exhaust gas recirculation control valve is closed in response to this, and the exhaust gas recirculation is stopped. The intake air cutoff effect of the intake air cutoff valve effectively acts to stop the operation of the diesel engine, and the diesel engine quickly stops its operation without causing large vibrations.

DESCRIPTION OF EMBODIMENTS The present invention will now be described in detail with reference to embodiments with reference to the accompanying drawings.

The attached figure shows an embodiment of a diesel engine equipped with an exhaust gas recirculation control device implementing the exhaust gas recirculation control method according to the invention. In the figure, 1 indicates a diesel engine, and the diesel engine has a cylinder bore 2.
A piston 3 is slidably received in the cylinder bore, and a combustion chamber 4 is defined above the piston 3. The diesel engine 1 communicates with the combustion chamber 4 through the nozzle 5.
% flow chamber 6, and the swirl chamber has a fuel injection nozzle 7.
Liquid fuel for diesel engines is now being supplied by injection.

The fuel injection nozzle 7 is supplied with liquid fuel by an electromagnetically controlled fuel injection pump 45 at a flow rate measured in accordance with the engine load. The electromagnetically controlled fuel injection pump 45 is of a distribution type that measures the amount of fuel to be injected according to the position of a spill ring (not shown) built into the pump. The spill position, that is, the amount of fuel injection is i-controlled in accordance with the current applied to the linear solenoid. Power supply control to the linear solenoid 24 is performed by control@@25 described later.

The diesel engine 1 sucks air into the combustion chamber 4 from an intake boat (not shown) through an intake control @ position 8 and an intake manifold 9, and exhausts exhaust gas from the combustion chamber 4 through an exhaust port 10 to an exhaust manifold 11. do. The intake boat and the exhaust port 10 are each opened and closed by poppet valves, and only the exhaust poppet valve 12 is shown in the figure.

The intake-n device 8 includes a main intake control valve 14 that opens and closes the main intake passage 13, and a sub-intake control valve 16 that opens and closes a sub-intake passage 15 provided by bypassing the main intake passage 13. . The main intake control valve 14 is drivingly connected to the accelerator pedal 17, and is located at the fully open position as shown in the figure when the accelerator pedal 17 is released, and opens as the amount of accelerator pedal 17 depression increases. In contrast, the auxiliary intake control valve 16 is drivingly connected to the double diaphragm device 18, and the diaphragm chamber 19
When atmospheric pressure is introduced into the diaphragm chamber 19 and negative pressure is introduced into the diaphragm chamber 20, the positions are at the fully open position as shown in the figure. located in the diaphragm chamber 19
When negative pressure is introduced into both the intake valves and 20, they are in the fully open position, and these two intake control valves throttle and shut off the intake air.

Diaphragm chambers 19 and 2 of double diaphragm @@18
0, negative pressure and atmospheric pressure are selectively introduced from negative pressure control valves 21 and 22, respectively. Negative pressure control valve 21
and 22 are electromagnetic negative pressure control valves which, when energized, introduce the negative pressure of the negative pressure supply device f23, which includes a negative pressure pump and a negative pressure tank, into the diaphragm chamber 19 or 20, and when not energized, the atmospheric pressure is introduced. is introduced into the diaphragm chamber 19 or 20. The negative pressure control valves 21 and 22 are energized and controlled by a control device 25, which will be described later.

The exhaust manifold 11 includes an exhaust gas intake boat 31.
Each intake manifold 9 is provided with an exhaust gas injection boat 32, and the exhaust gas intake boat 31 is connected to a conduit 33.
, exhaust gas 3 recirculation control valve 34 and conduit 35 are connected to exhaust gas injection boat 32 .

The exhaust gas recirculation control valve 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 in a diaphragm chamber 41 provided on one side of a diaphragm 40. When a negative pressure greater than a predetermined value is not introduced, the compression coil spring 42
When a negative pressure greater than a predetermined value is introduced into the diaphragm chamber 41, the valve boat 36 is pushed down by the spring force of the compression coil spring 42 to close the valve boat 36. It opens depending on the magnitude of the negative pressure.

Negative pressure is supplied to the diaphragm chamber 41 from a negative pressure regulating valve 43. The negative pressure regulating valve 43 is supplied with negative pressure from the negative pressure supply device 23, and the negative pressure is supplied to the negative pressure regulating valve 43.
The current signal is adjusted according to the current signal given to the diaphragm chamber 41, and is supplied to the diaphragm chamber 41.

Next, the M1111'#A position 25 will be explained with reference to FIG. The control device 25 includes a microcomputer 50
When the key switch 27 is closed, it is energized and starts, and after a predetermined period of several tens of seconds has elapsed since the key switch 27 is opened, the energization is stopped and the operation stops.

The microcomputer 50 includes an input boat device 51,
Random access memory (RAM) 52, read only memory (ROM) 53, and central processing unit (CPU)
) 54 and an output boat device 55, the rotation speed sensor 26 receives information regarding the engine rotation speed, and the key switch 27 receives information regarding the opening and closing of the engine.
Engine cooling water I from water temperature sensor 28! information about the marks,
The accelerator sensor 29 receives information regarding the amount of depression of the accelerator pedal 17, the intake pressure sensor 30 receives information regarding the intake pressure in the intake passage downstream of the intake control device 8 based on the intake flow, and the fully closed switch (idle switch) 46
Information regarding whether or not the main intake control valve 14 is in the fully closed position is given to each input boat device 51, and this information is taken into the RAM 52 and CPU 54, and the output boat device is loaded based on the program and data stored in the ROM 53. @55 Linear solenoid 24, negative pressure control valve 21.2
2. It is designed to output a control signal to each of the drive circuits 56 to 59 of the negative pressure regulating valve 43.

The CPU 54 calculates the basic fuel injection amount according to the accelerator pedal depression amount detected by the accelerator sensor 29 and the engine speed detected by the rotation speed sensor 26, or reads it from the data memory of the ROM 53 and determines the basic fuel injection amount. The injection amount is calculated and corrected according to the engine cooling water temperature detected by the water temperature sensor 28 and the intake pressure detected by the intake pressure sensor 30, and a fuel injection amount signal based on the calculation result is sent from the output boat 55 to the drive circuit 56. It is designed to output to.

The drive circuit 56 includes a servo amplifier circuit, receives information regarding the position of the spill ring of the fuel injection pump 45 from the spill position sensor 44, and receives a fuel injection amount signal from the microcomputer 50, in other words, a control target spill position signal. and the spill position signal from the spill position sensor 44, and based on the comparison result, the linear solenoid 2 is adjusted so that the actual spill ring position becomes the control target position.
A control command signal is output to 4. As a result, the spill ring beam of the fuel injection pump 45 is driven by the near solenoid 24 and its position is feedback-controlled, and the fuel injection pump 45 pumps liquid fuel to the fuel injection nozzle 7 at a flow rate corresponding to the fuel injection amount.

When the key switch 27 is closed and the engine cooling water temperature detected by the water temperature sensor 28 is below a predetermined value, for example 60°C, the CPU 54 outputs an off signal to both drive circuits 57 and 58, and the engine cooling water temperature is lowered. is greater than a predetermined value, an ON signal is output only to the drive circuit 58, and when the key switch 27 is opened and the engine is stopped, the drive circuits 57 and 58 are turned on until a predetermined time of several tens of seconds has elapsed from the time the key switch 27 was closed. It is designed to output an on signal to both.

By outputting control signals to the drive circuits 57 and 58 as described above, the auxiliary intake control valve 16 is brought to the fully open position when the engine 111 is running, and is brought to the half open position after completion of warm-up, and the key switch is pressed. 27 is opened and brought to the fully open position when the operation of the diesel engine 1 is stopped.

As described above, the ROM 53 stores the optimal exhaust gas recirculation amount in accordance with the fuel injection amount and the engine speed as a two-dimensional map using the locked out fuel injection amount and the engine speed detected by the speed sensor 26 as variables. is stored, and while the key switch 27 is closed, the CPU 54 determines the optimal exhaust gas regeneration according to the two control variables based on the fuel injection amount and the engine speed detected by the rotation speed sensor 26. The data value of the circulation flow rate is read from the ROM 53, and interpolation calculation is performed according to the data value or from the data value so that exhaust gas recirculation is performed at a predetermined flow rate during idle operation and low to medium load specific load operation. A pulse signal with a duty ratio corresponding to the determined optimal exhaust gas recirculation flow rate is output from the output boat 55 to the drive circuit 59, and the key switch 27
When the exhaust gas recirculation is opened, an off signal is output from the output port to the drive circuit 59 so that exhaust gas recirculation is immediately stopped.

As best shown in FIG.
It has an A exchanger 60, an amplifier 61, an oscillator 62, a comparator 63, and a transistor 64, and converts a pulse signal with a predetermined duty ratio given from the microcomputer 50 into a current signal according to the duty ratio. The current signal is converted and supplied to the negative pressure regulating valve 43.

The negative pressure regulating valve 42 is supplied with a current signal as described above, thereby supplying a negative pressure greater than a predetermined value to the diaphragm chamber 41 of the exhaust gas recirculation control valve 34 during idle operation and during specific low to medium load operation. and key switch 27
Immediately after opening, the supply of negative pressure greater than a predetermined value to the diaphragm chamber 41 is stopped.

Therefore, during idling operation and specific load operation from low to medium load, the exhaust gas recirculation control valve 34 opens according to the operating state of the diesel engine at that time, and exhaust gas is recirculated at a flow rate corresponding to the flow rate of the valve. Circulation takes place and key switch 27
As soon as the exhaust gas recirculation control valve 34 is closed, the exhaust gas recirculation control valve 34 is closed and exhaust gas recirculation is stopped.

As mentioned above, when the key switch 27 is opened, exhaust gas recirculation is immediately stopped, and if the accelerator pedal 17 is not depressed at this time, both the main intake control valve 17 and the auxiliary intake control valve 16 are in the fully closed position. When the intake passage ゛ is blocked by these two intake control valves, the diesel engine 1 no longer takes in fresh air or exhaust gas, and the intake air blocking effect effectively works to stop the operation of the diesel engine 1. However, the diesel engine 1 immediately stops operating without causing any large vibrations.

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 embodiments are possible within the scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a diesel engine equipped with an exhaust gas recirculation device that implements the exhaust gas recirculation control method according to the present invention, and FIG. 2 is a schematic configuration diagram of the diesel engine shown in FIG. 1. FIG. 3 is a block diagram showing the drive circuit of the exhaust gas recirculation control t11I device. 1...Diesel engine, 2...Cylinder bore, 3.
... Piston, 4... Combustion chamber, 5... Injection 0.6...
- Vortex chamber. 7... Fuel injection nozzle, 8... Intake control device, 9...
...Intake manifold, 10...Exhaust boat, 11.
...Exhaust manifold, 12...Poppet valve, 13.
...Main intake passage, 14...Main intake control valve, 15...
Sub-intake passage. 16... Sub-intake control valve, 17... Accelerator pedal,
18...Duffle diaphragm device, 19.2'O...
・Diaphragm chamber, 21.22... Negative pressure control valve, 23
... Negative pressure supply @ position, 24 ... Linear solenoid, 2
5... Control device, 26... Rotation speed sensor, 27...
・Key switch, 28...Water temperature switch, 29...
accelerator sensor. 30... Intake pressure sensor, 31... Exhaust gas intake boat, 32... Exhaust gas injection boat, 33... Conduit, 34... Exhaust gas recirculation control valve, 35... Conduit,
36... Valve boat, 37... Valve element, 38... Valve rod, 39... Diaphragm device, 40... Diaphragm, 41... Diaphragm chamber, 42... Compression coil spring, 43 ...Negative pressure regulating valve, 44...Spill position sensor, 45...Fuel injection pump, 46...Full close switch, 50...Microcomputer, 61...
・・Input port, 52 ・・Random access memory,
53... Read-only memory 1c 54-... Central processing unit, 55... Output port, 56-59... Drive circuit, 6O... D/A converter. 61... Amplifier, 62... Oscillator, 63... Comparator, 64-t-transistor Patent applicant Toyota Motor Corporation Representative Patent attorney Masaki Akashi

Claims (1)

[Claims] In an exhaust gas recirculation control method for a diesel engine, in which the intake passage is blocked by an intake cutoff valve when the key switch is opened to stop operation, the exhaust gas recirculation control valve is opened during idle operation to block the exhaust gas. A method for controlling exhaust gas recirculation, comprising performing recirculation and closing the exhaust gas recirculation control valve in response to opening of the key switch when the operation is stopped.