JPH11241627A - Egr device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect atmospheric pressure and rightly correct a target injection rate in association with detection of the atmospheric pressure by judging EGR non-execution in a condition in which a value detected by a negative pressure sensor is a prescribed atmospheric pressure corresponding value, when non- execution of an EGR is decided, or while a non-execution command signal is outputted. SOLUTION: In an EGR judging unit 6 for inputting rotating speed NE, a final target injection rate Qdsr, and intake negative pressure Pv, it is judged whether it is in an operating condition for executing the EGR or not. When it is in an EGR executing region, intake negative pressure PV is memorized in a memory as EGR negative pressure, and a flag showing execution of EGR is set. On the other hand, the intake negative pressure Pv is compared with a prescribed value corresponding to the atmosphere in an EGR non-execution region, the detected value Pv is memorized as the atmosphere when the intake negative pressure Pv is the prescribed value and less, and also the flag showing execution of the EGR is reset. When the detected value Pv is the prescribed value or more, a main routine is completed without renewing the EGR negative pressure and the atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR (exhaust gas recirculation) device, and more particularly to an EGR device having an EGR valve which is opened and closed by a negative pressure actuator.

[0002]

2. Description of the Related Art An EGR system having an EGR valve which is opened and closed by a negative pressure actuator is disclosed in Japanese Patent Laid-Open No. 8-232.
No. 770. In this EGR system,
A pressure sensor is provided in a negative pressure path between the negative pressure actuator and the EGR valve, and the detected value of the pressure sensor at regular intervals is given to the controller as usual, thereby realizing the actual EG.
Feedback control of the actual valve opening is performed as a substitute parameter for the R valve opening.

In this case, the controller uses the pressure value detected from the pressure sensor to calculate the actual EGR value during the execution of EGR.
It is recognized as the valve opening, and is recognized as the atmospheric pressure while EGR is not being performed, and the atmospheric pressure of the target injection amount is corrected. This eliminates the need to separately install an atmospheric pressure sensor, thereby simplifying the apparatus.

[0004]

However, in such a conventional EGR system, whether the EGR is being performed or not is determined by the engine operating state (rotational speed and load) or a control valve (a negative pressure actuator). EVRV) based on the command signal (duty ratio)
As shown by the dotted line in FIG. 1, the atmospheric pressure value Pv recognized immediately after the transition from the EGR execution state (ON) to the non-execution state (OFF) may have a large error from the actual atmospheric pressure Pa. In some cases, the correction of the injection amount was adversely affected.

[0005] This is because there is a delay in the operation of the control valve (EVRV) and the pressure change in the negative pressure path with respect to the EGR execution command and the non-execution command. That is, immediately after the controller issues the EGR non-execution (OFF) command, although the negative pressure still remains in the negative pressure path, the detected value at this time is to be recognized as the atmospheric pressure. Will be adversely affected.

Therefore, according to the present invention, the EGR valve provided on the EGR path from the exhaust pipe to the intake pipe is opened and closed by the controller controlling the negative pressure actuator.
In a GR device, an object is to make a value detected by a negative pressure sensor correspond to an actual atmospheric pressure when EGR is not performed.

[0007]

In order to achieve the above object, an EGR device according to the present invention comprises: a negative pressure sensor for detecting a pressure in a negative pressure path between the EGR valve and the negative pressure adjusting means;
Further comprising an engine operating state detecting means, wherein the controller determines execution / non-execution of EGR according to the engine operating state, and outputs an execution command signal to the negative pressure adjusting means;
When the execution of the EGR is determined or the execution command signal is being output, E
It is determined that the GR is being executed, and a state where the non-execution of the EGR is determined or the non-execution command signal is being output and the value detected by the negative pressure sensor is a predetermined atmospheric pressure equivalent value is determined as the EGR not being executed. It is what it was.

That is, according to the present invention, the controller comprises an EG
When the execution of the R is determined (when the EGR execution command signal is output), it is determined that the EGR is being executed as usual.
The non-execution determination is performed when the controller determines that the EGR is not to be performed (when the EGR non-execution command signal is being output) and when the detection value of the pressure sensor is equal to the atmospheric pressure. Is going. Therefore, it is possible to correctly detect the atmospheric pressure and correct the target injection amount accompanying the detection.

The controller calculates the maximum allowable injection amount using the detection value of the negative pressure sensor when it is determined that the EGR is not being performed, and calculates the maximum allowable injection amount based on the maximum allowable injection amount and the engine operating state. The smaller of the target injection amounts obtained can be the final target injection amount.

Further, the engine operating state includes the engine speed and load and the final target injection amount, and the controller determines the target injection amount based on the engine speed and load. The execution / non-execution of EGR can be determined based on the engine rotation speed.

[0011]

FIG. 2 shows an embodiment of an electronically controlled fuel injection device for a diesel engine including an EGR device according to the present invention. The diesel engine 1 is, for example, a four-cycle four-cylinder direct injection engine. The controller (ECM) 2 performs a fuel injection control based on output signals of various sensors provided in an intake system, an exhaust system, and the like.

More specifically, an equally-spaced gear 5 partially having a toothless portion 4 fixed to the crankshaft 3 of the engine 1
A rotation speed sensor 6 constituted by an electromagnetic pickup so as to be electromagnetically coupled with the controller 2 detects the rotation speed (NE) of the engine 1 and provides the rotation speed (NE) to the controller 2. An accelerator opening sensor 8 composed of a potentiometer detects the amount of depression of the accelerator pedal 7 (accelerator opening: ACL) and supplies the detected amount to the controller 2. The controller 2 converts the accelerator opening of the analog signal into a digital signal and takes it in. The rotation speed sensor 6 and the accelerator opening sensor 8 provide the engine 1
Of the minimum operation state detecting means.

The operating state detecting means preferably includes an intake pressure sensor 10 provided at a position shown in the drawing so as to detect the intake pressure of the intake pipe 9 and an engine water temperature provided at a head 11 above a cylinder 12 of the engine 1. A water temperature sensor 13 for detecting the air temperature, an intake air temperature sensor 14 for detecting the intake air temperature of the intake pipe 9 and the like are usually provided and connected to the controller 2.

A hydraulically operated unit injector 16 is provided above the cylinder 12 so that fuel is directly injected into the cylinder 12. The injector 16 is connected so that high-pressure oil is supplied from a high-pressure oil pump 18 and low-pressure fuel is supplied from a fuel pump 19 via an oil rail 17 placed beside the cylinder head 11. . The high-pressure oil is pressure-controlled by the controller 2 via a control valve (RPCV) 20.

That is, a relatively low-pressure fuel is supplied from a fuel pump 19 to a fuel chamber formed inside the injector 16, and the fuel is driven (stroke-driven) by high-pressure oil from an oil pump 18. The fuel is injected at an injection pressure independent of the engine speed by pressurizing with a plunger (not shown). The oil pressure (oil pressure) at this time is detected by the sensor 21a,
The oil temperature is detected by the sensor 12b and fed back to the controller 2.

An electromagnetic valve (not shown) is provided in a path for supplying the high-pressure oil of the oil pump 18 from the oil rail 17 to the pressure-increasing plunger pressure receiving surface in the injector 16. The fuel injection is performed by controlling the energization (valve opening) by a control signal from the controller 2.

That is, the controller 2 determines the energizing time (pulse width or duty ratio) to the solenoid valve based on the target injection amount, and energizes the solenoid valve with this pulse width to thereby control the solenoid valve to apply a current from the injector 16. Control the fuel injection amount. Reference numeral 22 denotes a glow plug for assisting engine start.

The exhaust pipe 23 and the intake pipe 9 of the engine 1
An EGR (exhaust gas recirculation) pipe 24 is connected between the exhaust gas and the exhaust gas, and a part of the exhaust gas is returned to the intake side to lower the combustion temperature of the engine 1 to reduce nitrogen oxides. . An EGR valve 25 including a negative pressure diaphragm is provided in the middle of the EGR pipe 24. This EGR valve 2
Reference numeral 5 denotes a controller in which a valve lift amount is controlled by a negative pressure control valve (EVRV) 27 utilizing a negative pressure from a vacuum pump 26 as a negative pressure source, and the lift amount (negative pressure) is detected by a negative pressure sensor 29 and the controller 2 is given.

Further, an oil temperature sensor 30 provided at a position where the operating oil temperature of an automatic transmission (not shown) can be detected, and a shift position provided at a position where a shift position of a shift lever (not shown) can be detected. A detection switch 31 and a key switch 32 for detecting the position of an ignition key are connected to the controller 2. The fuel injection control system is described in more detail in Japanese Patent Application Laid-Open No. 6-511527.
Can be referred to.

FIG. 3 is a conceptual diagram showing the calculation of the target injection amount by the controller 2. First, in the basic target injection amount calculation unit, the rotation speed NE detected by the rotation speed sensor 6 and the accelerator opening ACL detected by the accelerator opening sensor 8 are set.
Thus, the basic target injection amount Qbase is obtained by referring to the map.

The basic target injection amount calculation unit may include an idle target injection amount calculation unit, an idle determination unit, and a switching unit (not shown), in addition to the basic target injection amount calculation unit itself. The idle target injection amount calculation unit calculates the idle target injection amount Qfc corresponding to the water temperature Tw detected by the water temperature sensor 13 by using the rotation speed NE and the idle target rotation speed Nid.
The idling target injection amount Qidle is obtained by correction by PID control based on the deviation from le.

Further, in the idling determination section, the rotational speed N
When E is within a predetermined low speed range and accelerator opening ACL is equal to or less than a predetermined low opening (for example, 0%), it is determined to be an idle state, and otherwise, it is determined to be a non-idle state.

The switching unit selects the basic target injection amount Qbase from the basic target injection amount calculation unit when the idle determination unit determines that the idle state is not set, and selects the idle target injection when the idle determination unit determines the idle state. The idle target injection amount Qidle from the amount calculation unit is selected. Then, regardless of the selected target injection amount Qbase / Qidle, it is output as the basic target injection amount Qbase.

In the correction section, the oil temperature correction amount Qoil based on the water temperature Tw detected by the water temperature sensor 13 or the oil temperature Toil detected by the oil temperature sensor 21b as disclosed in Japanese Patent Publication No. 6-511526, Various correction amounts Qcomp such as a correction amount Qm based on the intake air temperature Tm are obtained.

The above correction amount Qcomp is changed to the basic target injection amount Qba.
The corrected target injection amount Qcrct is obtained by adding (subtracting in some cases) to se. The maximum allowable injection amount calculation unit, from the rotational speed NE atmospheric pressure P v air, the maximum allowable injection amount Qlmt is determined by the map reference. This is because the value of the atmospheric pressure differs depending on whether the traveling path is at highland or lowland.

The above-mentioned map is divided into a map (W.EGR) set when EGR is executed and a map (WO.EGR) set when EGR is not executed. The selection is made according to the state (flag F e gr). The minimum value determination unit (MIN) determines the smaller one of the corrected target injection amount Qcrct and the maximum allowable injection amount Qlmt, and the switching unit selects one of them according to the determination, and determines the final target amount. The injection amount is Qdsr.

The controller calculates the target injection amount Qdsr at regular time intervals. Further, the controller determines the pulse width of the solenoid valve of the injector based on the final target injection amount Qdsr by interrupt processing when the predetermined crank angle (BTDC40 ° CA) before the fuel injection of each cylinder is reached.

In the EGR determination section, the rotational speed NE
It is determined whether EGR is being executed or not based on the final target injection amount Qdsr and the detection value Pv of the negative pressure sensor 29. The EGR determination unit is executed every time the negative pressure sensor Pv is read (A / D conversion), and a map in the maximum allowable injection amount calculation unit is selected based on the determination result.

FIG. 4 shows a flowchart of the determination process in the EGR determination section. First, in step S1, E is calculated from the rotational speed NE and the target injection amount Qdsr at that time.
It is confirmed whether or not the operating condition is such that the GR is to be executed.
When it is in the GR execution area, the negative pressure sensor 2
The detection value Pv of 9 stores in a memory (not shown) as EGR negative pressure P v egr is a surrogate parameter of the actual EGR valve opening, and sets the flag F e gr indicating that the EGR performed at step S3 Then, this routine ends.

[0030] When it is EGR non-execution region in step S1 described above has been confirmed, the program proceeds to a step S4, the predetermined value P v atmospheric pressure corresponds showing a detection value Pv of the negative pressure sensor 29 in FIG. 1 lv (which is a threshold value predetermined in consideration of the fluctuation range of the atmospheric pressure) compared with the predetermined value P v Lv subatmospheric P v ai detected value Pv in step S5 when the (atmospheric pressure equivalent)
Reset the flag F e gr indicating that the EGR performed in step S6 and stores as r, the routine ends.

[0031] Thus, becomes possible to constantly update the current atmospheric pressure P v air after becoming a Pv <P v Lv. At this time, the controller 2 is outputting the EGR non-execution command signal. In the example of FIG. 1, the larger the value on the vertical axis, the larger the negative pressure.

Further, when the detection value Pv is equal to or higher than the predetermined value P v Lv in step S4, since the still negative pressure in the negative pressure path is left (command's EGR is not executed but the EGR valve is closed Therefore, this routine ends without updating both the EGR negative pressure P v egr and the atmospheric pressure P v air.

FIG. 5 is a flowchart showing the operation of the maximum allowable injection amount calculating section. First, in step S11, E
Check the above flags F e gr is the determination result of the GR determination unit, if it is set, the map corresponding to the EGR performed at step S12 (W. EGR), and stores the rotational speed NE and the large Maximum injection quantity Ql from pressure Pv air
seeking mt, if the flag F e gr is cleared, the map corresponding to the EGR is not executed in step S13 (WO.E
GR) to determine the maximum injection amount Qlmt.

FIG. 6 shows a flowchart for controlling the EGR valve. First, in step S21, as in step S1, the rotational speed NE and the target injection amount Qdsr are used to calculate E
It is confirmed whether or not the operating condition is such that the GR control is to be executed.

As a result, when the engine is in the EGR execution region, in step S22, the target EGR negative pressure P v re corresponding to the target opening of the EGR valve is obtained from the rotation speed NE and the target injection amount Qdsr.
calculated from a map reference to f, detected in the target negative pressure P v ref and the negative pressure sensor 29 in step S23 (the memory) the E
A deviation ΔPv from the GR negative pressure P v egr is calculated, and step S2 is performed.
In P4, the control valve (E
A target duty ratio (Duty) of (VRV) 27 is obtained.

If it is determined in step S21 that the EGR is not in the EGR non-execution region, the flow advances to step S25 to set the target duty ratio (Duty) to 0%. In step S26, the target duty ratio determined in step S24 or S25
(Duty), a drive signal is output to the control valve (EVRV) 27.

In the above embodiment, "EGR execution / non-execution" includes not only the determination of execution / non-execution of EGR in the controller, but also a signal such as a duty ratio for actually controlling the EGR valve. It is also possible to determine whether EGR is performed or not.

In the above embodiment, the control is performed with the target injection amount. However, it goes without saying that the pulse width (duty ratio) of the command pulse to the solenoid valve in the injector may be corrected.

[0039]

As described above, the EGR according to the present invention is
The device determines that the execution of the EGR is determined according to the engine operating state or that the execution command signal is being output, that the EGR is being executed, and that the EGR is not determined or the non-execution command signal is being output and the negative pressure sensor is Since the state in which the detected value is a predetermined atmospheric pressure equivalent value is determined to be not performing EGR, even when the EGR non-execution is determined, the true EGR non-execution is performed when the EGR valve is actually closed. The execution state can be determined. Therefore, EG based on accurate atmospheric pressure
R control is realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of an EGR device according to the present invention and a conventional example.

FIG. 2 is a system configuration diagram showing one embodiment of an EGR device according to the present invention.

FIG. 3 is a block diagram conceptually showing the operation of the EGR device according to the present invention.

FIG. 4 is a flowchart of an EGR determination processing program executed by a controller in the EGR device according to the present invention.

FIG. 5 is a flowchart of a maximum allowable injection amount calculation program executed by a controller in the EGR device according to the present invention.

FIG. 6 is a flowchart of a control program for an EGR valve executed by a controller in the EGR device according to the present invention.

[Explanation of symbols]

1 is a diesel engine, 2 is a controller (EC
M), 3 is a crankshaft, 4 is a missing tooth portion, 5 is a gear,
6 is a rotational speed sensor, 7 is an accelerator pedal, 8 is an accelerator opening sensor, 9 is an intake pipe, 10 is an intake pressure sensor, 11
Is a cylinder head, 12 is a cylinder, 13 is a water temperature sensor, 14 is an intake air temperature sensor, 15 is an intake throttle valve,
5a is a throttle valve position sensor, 16 is an injector,
17 is an oil rail, 18 is an oil pump, 19 is a fuel pump, 20 is a control valve, 21a is a hydraulic pressure sensor, 21b is an oil temperature sensor, 22 is a glow plug, 23 is an exhaust pipe, 24
Is an EGR pipe, 25 is an EGR valve, 26 is a vacuum pump, 27
Denotes a negative pressure control valve (EVRV), 29 denotes a negative pressure sensor, 30 denotes an oil temperature sensor of the automatic transmission, 31 denotes a shift position detection switch, and 32 denotes an ignition key switch unit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] An EGR device in which a controller opens and closes an EGR valve provided in an EGR path from an exhaust pipe to an intake pipe by a negative pressure adjusting means, wherein a negative pressure between the EGR valve and the negative pressure adjusting means is provided. A negative pressure sensor for detecting a pressure in the path; and an engine operating state detecting means, wherein the controller determines whether or not to execute the EGR according to the engine operating state and executes the EGR on the negative pressure adjusting means. A command signal is output, and when the execution of the EGR is determined or during execution of the execution command signal, it is determined that the EGR is being executed, and when the non-execution of EGR is determined or the non-execution command signal is output and the detection value of the negative pressure sensor is A state in which a state corresponding to a predetermined atmospheric pressure equivalent value is determined to be not performing EGR,
GR device. 2. The controller according to claim 1, wherein the controller calculates a maximum allowable injection amount using a detection value of the negative pressure sensor when it is determined that the EGR is not being performed, and calculates the maximum allowable injection amount and the engine. An EGR device characterized in that a smaller one of target injection amounts obtained based on an operation state is a final target injection amount. 3. The engine operating state according to claim 1, wherein the engine operating state includes an engine speed and a load, and the final target injection amount.
An EGR apparatus characterized in that the target injection amount is obtained based on a rotation speed and a load of the engine, and execution / non-execution of EGR is determined based on the engine rotation speed and the final target injection amount.