JPS6341654A - Exhaust gas recirculation control apparatus for diesel-engine - Google Patents

Abstract

PURPOSE:To always obtain an appropriate EGR amount, by comparing an intake-air pressure during engine stopping with an intake-air pressure during idle operation to estimate the clogging of an air-cleaner in view of a pressure differential therebetween, and by correcting an EGR value in accordance with the estimation. CONSTITUTION:A fuel injection pump 24 for controlling the amount of fuel injection for a Diesel-engine 10 is provided with a sensor 28 for detecting the opening degree of an adjusting lever 26 linked to an accelerator pedal and a sensor 30 for detecting the rotational speed of the engine 10. Further, the engine 10 is provided with a sensor 32 for detecting the temperature of water and a sensor 34 for detecting the pressure of intake-air. An ECU 36 controls the opening degree of an EGR valve 20 through the intermediary of an EVRV (electronically controlled vacuum selector valve) 38 in accordance with signals delivered from sensors 28 through 34. That is, the clogging of an air-cleaner 14 is estimated from the pressure differential between intake-air pressures during engine stopping and during idle operation, and an EGR amount is corrected in accordance with the estimation.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an exhaust gas recirculation control device for a diesel engine, and more particularly, to an exhaust gas recirculation control device for a diesel engine that controls the amount of exhaust gas recirculated based on an output signal of an intake pressure detection means provided in an intake pipe. Concerning improvements to gas recirculation control equipment.

[Prior art 1] In diesel engines, as a means of reducing NOx in exhaust gas, a part of the inert exhaust gas is recirculated to the intake system, and the exhaust gas is mixed into the intake air (intake air). By lowering the maximum temperature during combustion, N
Exhaust gas recirculation (EGR) reduces the generation of Ox.
) device is used. When the intake air volume of a diesel engine decreases due to intake throttling or high-altitude driving, if EGR is performed at the same flow rate as when the intake air volume does not decrease, it will naturally not work properly, especially in high-load operating ranges where there is little intake surplus air. E G R
ht could not be obtained, resulting in a lack of M water in the air-fuel mixture, and the amount of white smoke or black smoke discharged increased. To deal with such problems, it is necessary to perform altitude compensation for EGR in order to perform the intake throttle or proper EGR when driving at high altitudes. EGR altitude compensation is the limit FG that does not generate white or black smoke due to changes in altitude due to ground driving, etc.
This is done because the R rate changes. Regarding the altitude compensation of this j;
There is a method for controlling exhaust gas recirculation of a diesel engine, such as that disclosed in US Pat. No. 9,215,954. In this exhaust gas recirculation control method, by detecting the intake pressure and reducing and correcting EGRm in accordance with the decrease in the intake pressure, white smoke or black smoke can be detected for a long time in a high-load operating range. It controls EGR suspension. That is, this method:
Since the intake pressure decreases as the atmospheric pressure decreases due to intake throttling or passengers traveling at high altitudes, the basic E By reducing and correcting 'i in accordance with the decrease in intake pressure, even if the intake air amount decreases due to intake throttling or high-altitude driving, the FOR is corrected to reduce the amount without causing an excessive flow rate. [Problems to be Solved by the Invention] By the way, as the vehicle changes over time, the air intake pressure decreases without clogging of the air cleaner element.
GRid is determined by the differential pressure between the top and downstream of the GR valve, so the EGR rate may become excessive. In order to compensate for the excessive FGR rate due to such clogging, it is conceivable to reduce the EGR by altitude compensation. However, when the vehicle moves from flat ground to high ground, the TJI air pressure decreases as well as the intake pressure, resulting in a drop in both intake and exhaust pressure.However, when the air cleaner element becomes clogged, the intake pressure decreases. The pressure will only drop, and the drop in pressure is greater than if you moved from the plains to the highlands. Therefore, the above-mentioned Ff.
In the control method for high-level compensation of FGR as proposed in No. 215954, when air cleaner element 1~ is clogged, the amount of EGR varies and proper EGR cannot be achieved.
The problem was that it was not possible to correct the weight loss.

[Means to solve the problem]

The present invention is installed in the intake pipe.

[In an exhaust gas recirculation control 1211 device for a diesel engine that controls υ1 gas recirculation based on the output signal of the intake pressure detection means, the engine stops when detected by the intake pressure detection means. means for comparing intake pressures at idle time and idle time to determine a pressure difference therebetween; means for estimating clogging of an air cleaner provided in the intake pipe from the determined pressure difference; The above object is achieved by including means for correcting the amount of gas recirculation. [Function] When a vehicle equipped with a diesel engine moves from a flatland to a highland, both the intake pressure (negative pressure) and the air pressure decrease, but when the air cleaner of the diesel engine's intake system becomes clogged, In this case, only the intake pressure decreases. Considering that the intake pressure is the same when going from a flatland to a highland and when the air cleaner is clogged on a flatland,
Although the amount of exhaust gas emitted from a diesel engine is the same, the atmospheric pressure in the wake of the exhaust system is different (usually higher on level ground), so the exhaust pressure is higher when the air cleaner is clogged on level ground. This is because it becomes or,
When exhaust gas recirculation (EGR) is performed, EGRfif differs depending on the differential pressure between intake pressure and exhaust pressure. It is not possible to correct the appropriate amount of EGR. In other words, the conventional EGR correction by altitude compensation according to the intake pressure (negative pressure value) is a high-altitude weight reduction correction, so if the intake pressure decreases at high altitudes, the exhaust pressure also decreases accordingly. When the air cleaner becomes clogged as described above, only the intake pressure decreases and the decrease in exhaust pressure is minute, so the conventional weight loss correction using altitude compensation cannot accurately correct EGR. The present invention has been made based on the above knowledge, and it compares the intake pressure when the engine is stopped and when the engine is idling, determines the pressure difference between them, and estimates the clogging of the air cleaner from the pressure difference. Based on the blockage, EGR
Correct fa. Therefore, even when the air cleaner of the intake system becomes clogged due to changes over time, it is possible to appropriately correct the EGR amount and reduce variations in the EGR amount. Furthermore, when EGR is performed, even if the EGR valve opening is constant, EGRla varies depending on the differential pressure between the intake pressure and exhaust pressure of the diesel engine. Therefore, even in the same type of engine, if the intake and exhaust systems differ depending on the vehicle in which it is installed, the intake and exhaust pressure will differ and the E G Rffl will also differ, so the E
It was necessary to adapt the operation of the GR valve. Normally, the pressure difference in the exhaust system of each vehicle is small and EGRffl is substantially determined by the pressure in the intake system. Therefore, if the EGR control device according to the present invention is used, the pressure difference in the intake system of a diesel engine can be corrected and the EGRffl can be adjusted. can be controlled with high precision. Therefore, according to the present invention, the EGR control device can be used without limiting the vehicle in which it is installed, and generalization becomes possible. [Examples] Examples of the present invention will be described in detail below. In this embodiment, an exhaust gas recirculation (EGR) control 611 provided in a diesel engine 10 as shown in FIG.
It is a device. In the figure, a diesel engine 10 includes air cleaners 1 to 14 for cleaning air (intake air) taken in from an intake pipe (intake manifold) 12, and an intake pipe that is connected from an exhaust pipe 16 to an EGR port 18. an EGR valve 20 for performing EGR during 12;
A vacuum pump 22 driven by the diesel engine 10 to generate negative pressure is provided. The fuel injection pump 24 for controlling the amount of fuel injected into the diesel engine 10 includes an adjusting lever 26 that rotates in conjunction with, for example, an accelerator pedal (not shown), and an adjusting lever 26 that controls the opening degree of the adjusting lever 26. A lever opening sensor 28 for detecting the accelerator opening Acc+, and a rotation speed sensor 30 for detecting the engine rotation speed NE are provided. Further, the diesel engine 10 has a water temperature TH of the diesel engine 10.
A water temperature sensor 32 for detecting W, an intake pressure sensor 34 for detecting intake pressure Pim in the intake pipe 12,
will be provided. Output signals from each of the sensors are input to an electronic control unit (hereinafter referred to as FCU) 36 for comprehensively controlling the diesel engine 10. on the other hand,
The output negative pressure of the vacuum pump 22 is transferred to the EG via an electronically controlled negative pressure switching valve (hereinafter referred to as EVRV) 38.
It is input to the R valve 20. Therefore, the opening degree of the EGR valve 20 is controlled by 1 lil according to the control negative pressure adjusted by the EVRV 38 based on the output of the ECIJ 36. The schematic configuration of the electrical system and signal input/output of the EGR111 control device are shown in the block diagram of FIG. 2. The effects of the embodiment will be explained below. The EGR control device of this embodiment is controlled based on the control procedures shown in FIGS. 3 and 4 stored in the ECU 36. In Figure 3, first, the ignition switch is turned on.
After starting the engine (step 110) and performing processing such as initialization (step 120), the value of the intake pressure Pim is left as PimS only when the engine speed NE=O, that is, when the engine is stopped ( Steps 130, 140). Next, the main routine is entered, and only when the engine 10 is in an idle state, the value of the intake pressure Pim is entered in Piml and left there (steps 150 and 160). Then, the EGR control routine shown in FIG. 4 is entered. Once this EGR control routine is entered, the engine speed NE, accelerator opening Acc+1, intake pressure Pi
(Step 170), g + book EG Rf
i fE G RB wo calculation-J-ru (S'i""/B18o). Then, the intake pressure P i when the engine is stopped and when the engine is idling
The difference Δpim between mS and P iml is calculated using the following equation (1) (step 190). p 1m5- p i+ul-ΔPim-(1)
Next, a correction coefficient Ko is determined from the calculated intake pressure difference ΔPim using the J: U relationship shown in FIG. 5 (step 200). The relationship shown in the figure is determined in advance by testing, and is based on the 6N correction coefficient K. clogging of air cleaner elements 1 to 14 is determined by
ff can be determined. Next, other correction coefficients Ki are calculated from the intake pressure Pim based on the relationship shown in FIG. 6 (step 210).
. Note that the relationships shown in the figures are also determined in advance through tests. Next, the calculated correction coefficients Ko and K+ are combined with the basic EGRBEGRB as shown in the following equation (2) to obtain the "GR command value FGR".
is calculated and reversed (step 22o). + ・EGRB → EGR- (2) Next, the calculated EGR command (lI'IF GR is set to the output port and the E
L is varied (step 230). In this embodiment, since the correction coefficient Ko is determined as shown in FIG. 5, the difference in intake pressure Δpin+ is 0.
〜Pimo, start the weight loss at △pi+n-Pimo, and shut off EGR when ΔPim≧pim1. Prevents E G RB+ from becoming excessive when the element 14 is clogged,
It is possible to prevent the generation of black smoke and white smoke. In the above embodiment, the EGR is controlled by the ECU 36 according to the control procedure shown in the flowcharts shown in FIGS. 3 and 4.
Control B211? Although the exhaust gas recirculation control device shown in FIG. . Also, in that case, the correction coefficient Ko
, the relationship for excluding + from -11 = is not limited to that shown in FIGS. 5 and 6. In addition, in the embodiment described in 6Fi, the case where the present invention is applied to a heavy-column control diesel engine as shown in FIG. It is clear that the present invention is not limited to, but can be applied to other diesel engines equipped with other electronic control 211 devices. (Effects of the Invention) As explained above, according to the present invention, the air cleaner becomes clogged over time and the pressure in the intake system decreases, thereby correcting variations in bFGR amount with good viscosity and obtaining appropriate EGR&i. I can. In addition, the difference in EGRffl can be corrected based on the difference in intake pressure between when the engine is stopped and when the engine is idling.
The EGR control device can now be used without limiting the type of vehicle in which it is installed, and has excellent effects such as being able to be used for general purposes.

[Brief explanation of the drawing]

FIG. 1 shows the configuration of an exhaust gas recirculation control device for a diesel engine in which the present invention is implemented, and a layout diagram including a partial block diagram. FIG.
Block diagram showing tua configuration and signal input/output, 3rd
4 and 4 are flowcharts showing the control procedure for explaining the operation of the embodiment, and FIG. 5 similarly shows an example of the relationship for calculating the correction coefficient Ko according to the difference in intake pressure. The diagram and FIG. 6 similarly show the correction coefficient ta according to the intake pressure.
It is a diagram showing an example of the lock-out relationship of K1. DESCRIPTION OF SYMBOLS 10... Diesel engine, 12... Intake pipe, 14... Air cleaner element, 16... Exhaust pipe, 18... EGR boat, 20... EGR valve, 28... Lever opening degree 30...Rotational speed control 4th node, 32...Water temperature sensor, 34...Intake pressure sensor, 36...ECU. 38-F V RV.

Claims (1)

[Claims] (1) In an exhaust gas recirculation control device for a diesel engine that controls the amount of exhaust gas recirculation based on an output signal of an intake pressure detection means provided in an intake pipe, the intake pressure detected by the intake pressure detection means is a means for comparing intake pressures when the engine is stopped and when the engine is idling, and determining a pressure difference therebetween; a means for estimating clogging of an air cleaner provided in the intake pipe from the determined pressure difference; An exhaust gas recirculation control device for a diesel engine, comprising: means for correcting the amount of exhaust gas recirculation based on the above.