JPS60150469A - Exhaust gas recirculation of diesel engine - Google Patents

Abstract

PURPOSE:To reduce concentration of NOX in exhaust gas by performing exhaust gas recirculation for predetermined time with predetermined amount with correspondence to specific engine operating condition under idling. CONSTITUTION:Under idling of engine, it will proceed to step 17. When it is not elapsed by predetermined time T from start of idling, it will proceed to step 21 while proceed to step 22 upon elapse of predetermined time T. In step 21, a pulse signal having predetermined duty ratio Eout based on the exhaust gas recirculation Ei determined in step 18 is fed to the negative pressure regulation valve. Consequently, concentration of NOX in exhaust gas under idling can be further reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an exhaust gas recirculation control method for a diesel engine used in a vehicle such as an automobile.

Background of the Invention In diesel engines used in vehicles such as automobiles, 1.
17 to reduce the degree of Noxlllll in the gas
It has already been proposed to perform 1st gas recirculation, and υ1st gas recirculation for diesel engines does not impede the operating performance of the diesel engine and does not involve the generation of white or black smoke. In order to convert a portion of the excess intake air drawn into the engine combustion chamber into exhaust gas, the flow rate should be adjusted according to the operating conditions of the diesel engine. When circulation occurs, harmful components such as sulfur oxides in the exhaust gas recirculated to the engine intake system cause severe corrosion and wear of the diesel engine components, resulting in so-called low-temperature corrosion, which reduces the durability of the diesel engine. is decreasing. For this reason, if exhaust gas recirculation is always performed during idling operation when the engine temperature drops due to a small amount of combustion fuel, there is a risk that low-temperature corrosion as described above will occur.

In view of the above-mentioned problems, Japanese Patent Application No. 58-920, filed by the same applicant as the present applicant, requires that exhaust gas be recirculated only for a predetermined period of time from the start of idling during idling.
No. 98 and Japanese Patent Application No. 58-20846.

By the way, this does not mean that the exhaust gas recirculation flow m during idling operation may always be a constant value, but rather in order to reduce as much as possible the N0XIIIJJ in the IA gas during idling operation. It is preferable that the flow rate is high when the engine temperature is high during idling operation.

OBJECTS OF THE INVENTION The present invention aims to appropriately control the 1-gas recirculation Wtfj during idling operation according to the temperature of the diesel engine during idling operation, thereby preventing low-temperature corrosion. In addition to avoiding the occurrence, it is possible to further reduce 4J (1111ft of NOx in gas) especially during idling operation.
It aims to provide 1.

Structure of the Invention As mentioned above, according to the present invention, what is the purpose of the invention during idle operation? - The engine temperature 1α before entering the idle operating state at 1α, 1 C, and the idle operating amount lh
Exhaust gas is recirculated only for a predetermined period of time, and during operation other than idling, the exhaust gas is recirculated at a predetermined flow rate (Ill gas i1) depending on the operating state of the engine. The characteristics are achieved by the exhaust gas recirculation control method of the easel engine.

Effects of the Invention The engine temperature characteristic 1g during idling operation is determined by the engine temperature at the start of idle operation, and the engine temperature at the start of idling operation is determined by the previous operating state of the diesel engine. When a diesel engine is operated at a high angle, it becomes very high; on the other hand, when a diesel engine is operated at a low load, it becomes low. According to the gas recirculation control method,
During idling, exhaust gas recirculation is performed only for a predetermined period of time at a diversion determined according to the operating state from the start of idling to the time before idling.
Low-temperature corrosion will not occur due to exhaust gas recirculation (especially)
The amount of NOxlG in the gaseous waste during idle operation is effectively reduced.

The exhaust gas recirculation flow 11 during idle operation is high when the diesel engine is operated at a high load before entering the idle operation state, and on the contrary, when the diesel engine is operated at a low load. It is set very low when That is, when the diesel engine is being operated with a load above a predetermined value, the counter is incremented by 1-, and when the diesel engine is not being operated with a load above the predetermined value, the counter is incremented. Exhaust gas recirculation flow during idle operation according to the counter value of the counter...
If it is determined, then J: Yes.

DESCRIPTION OF EMBODIMENTS The present invention will now be described in detail with reference to embodiments with reference to the attached figures fq.

FIG. 11 shows one embodiment of an IJI gas recirculation device implementing the exhaust gas recirculation control method according to the present invention. In the figure, 1 indicates a single engine UJ3, which has a piston 3 slidably received in a cylinder bore 2 and a combustion chamber 4 defined on one side of the piston. Further, a swirl chamber 5 communicating with the combustion chamber 4 is connected, and liquid fuel is supplied to the swirl chamber from a fuel injection nozzle (not shown).

The diesel engine 1 sucks air into the -C combustion chamber 4 through the intake manifold 6 and intake boats 1 to 7, and exhausts 1-1 air scum from the combustion chamber 4 to the DI air manifold 9 via the exhaust boat 8. It has become so. The intake bow 1-7 and the exhaust bow 1-8 are respectively opened and closed by valves to the exhaust valve 1, and only the exhaust valves 1 to 1 are shown by reference numeral 10 in the figure.

11 indicates an exhaust gas recirculation control valve. 1j1 Gas recirculation control valve 11 connects inlet boat 13 and outlet L1 boat 1-
14 and the casing 12 with an inlet port 1
3 is connected by a conduit 15 to an exhaust gas take-off boat 16 formed in the exhaust manifold 9, and the outlet [J boat 14
is connected by a conduit 17 to 1) a gas inlet port 1-'18 formed in the gas manifold 6;

The exhaust gas recirculation control valve 11 has a valve element 19 within the casing 12 which is drivingly connected to a diaphragm arrangement 23 via a valve rod 22 and which is connected to a tire phragm on one side of the diaphragm 25. When negative pressure is introduced into the palm 26 or when no negative pressure is introduced into the palm 26, the spring force of the compression spring 26 drives the valve to the left in the figure, and the valve seats 1 to 4 are seated on the valve seat portion 20.
21 is closed, and when negative pressure is introduced into the noram chamber 2G of the tie 17 (against the spring force of the compression coil spring 27, it is driven to the right B in Figure 4) -C valve seat portion 20 J: Su1
111 and opens the valve 1-21 according to the magnitude of the negative pressure.

The tie 17 noram chamber 2G is connected to the negative pressure output capos 1 to 30 of the C scent pressure regulating valve 29 through a guide pipe 28.

n1 regulating valve 25] is supplied with negative pressure from a negative pressure pump 32 through a lead 33 to t''4n-human power outputs 1 to 31, and controls the t''41[till equipment Fj 40 J: the electricity supplied. The pressure is regulated in accordance with the control signal)), and the regulated negative pressure is output from negative pressure output capos 1 to 330.

The control 1A device 40 may include a general micro combicoater and an up/down counter, and transmits information regarding the fuel injection blade ffi supplied to the diesel engine 1 from the fuel injection amount sensor 4J41 based on the rotational speed. The sensor 42 provides information regarding the rotation speed of the diesel engine 1, the idle switch/l-3 provides information regarding whether or not the diesel engine 1 is being operated at idle, and the water temperature sensor 44 provides information regarding the cooling water temperature of the diesel engine 1. Each information is inputted in advance, and control data related to the optimum illumination gas recirculation flow fftEr according to the fuel injection amount and rotation speed of the Deep Pill engine 1 and the optimum exhaust gas recirculation during idle operation are calculated. The control data related to the flow rate E1 is stored, and the exhaust gas recirculation control method according to the present invention is implemented according to the control data and the information from each sensor (JJ). A control signal is outputted to a negative pressure regulating valve 29 in accordance with the LC flower 1 shown in FIG.

The fuel injection amount sensor 1) 41 may be one that detects the displacement m of a fuel supply amount control element such as a spill ring of a fuel injection pump, or one that detects the amount of depression of an accelerator pedal.

Next, the method for controlling exhaust gas recirculation according to the present invention will be explained with reference to the flow jet shown in FIG.

In the first step 1, information is input from the fuel stone blower (sensor 41, rotary speed hinge 1) 42, idle switch 43, and water temperature sensor 144.

In step 2, it is determined whether or not the j fiddle switch 43 is in the ON state. When the idle switch 43 is not in the A state, that is, when the diesel engine 1 is in negative operation, proceed to step 3), whereas when the idle switch 43 is in the A state, that is, when the diesel engine 1 When the engine 1 is in idle operation, the process advances to step 17.

In the snowtube 3, it is determined whether the flag Fa is 1 or not. When the flag Fa=1, the process proceeds to step 5, whereas when the flag 1a=1r does not exist, the process proceeds to slap 4.

In step 4, flag switching is performed to set the flag Fa to 1.

In step 5, it is determined whether the flag Fb is O or old. When the flag Fb=O, the process proceeds to step 7, whereas when the flag Fb=0 is not, the process proceeds to step 6.

In step 6, flag switching is performed to set flag Fb to 0.

In step 7, the temperature of the cooling water of the diesel engine 1 detected by the water temperature sensor 44 is set to a predetermined value, for example 60.
A determination is made as to whether or not the temperature is at least ℃. When the cold Nlk temperature is above the predetermined value, the process proceeds to step 8; on the other hand, when the cooling water temperature is not above the predetermined value 1if*11., the process proceeds to step 13.

In step 8, the rotation speed of the diesel engine 1 detected by the rotation speed sensor 42 reaches a predetermined value, for example 200.
A determination is made as to whether or not the value is equal to or greater than Orpm. When the engine speed is above the predetermined value, the process proceeds to step 9, whereas when the engine speed is not above the predetermined value, the process proceeds to step 14.

In step 9, the fuel injection suspension sensor 4'1 detects that the fuel injection DA for the diesel engine 1 is greater than a predetermined value. A determination is made whether or not. - The fuel injection amount per row culm is a predetermined value, e.g. 2
When it is equal to or greater than 0III111, the process proceeds to step 10, and on the other hand, when the fuel injection regulation per stroke is not equal to or greater than the predetermined value, the process proceeds to step 14.

In step 10, the counter 1 of the -nono counter C
Step 10 is followed by step 11.

In step 11, the fuel injection sword ff1t IJ-/1
The control data corresponding to the fuel injection amount per culm and the rotational speed detected in 1) 42 is searched, and the exhaust gas is controlled based on this control data. A determination of the gas recirculation flow rate Er is made. The exhaust gas recirculation flow fltEr is determined by the amount of fuel injection from the basic concept of diesel engine exhaust gas recirculation, which is to recirculate a portion of the excess intake air from combustion into exhaust gas. In other words, the JIJ value of the engine increases (or decreases) depending on the engine speed, and also decreases as the engine speed increases. After step 11, proceed to step 12.

In step 12, in step 11, a predetermined decoupling ratio [Oul] is outputted to the negative 1f regulating valve 29.

The negative pressure regulating valve 29 outputs a negative JEf to the output boat 30 corresponding to the fuel jet suspension and rotational speed per stroke of the diesel engine 1 at that time by being given the pulse sever function. The negative pressure drives the Cυ1 gas recirculation control valve 1. (Before this, during load operation other than idling operation, U I] l
Gas recirculation takes place.

The next step after step 12 is [T1~].

In step 13, the counter 1 direct C of the counter is O.
be made into

In step 14, the counter (night C) is incremented by one. After step 14, the process advances to step 15.

In step 15, it is determined whether the counter 1 "IC" is smaller than O. If C<0, the process proceeds to step 16; on the other hand, if C<0, the process proceeds to step 11.

At step 16, at t, the counter value C of the counter is O.
be made into After step 16, the process advances to step 11.

In step 17, -C makes a 711 determination as to whether the flag [a is 1 or not. When the flag Fa=1, the process advances to step 18, whereas the flag Fa-I
If there is no F, proceed to step 23.

In step 1B, it is determined whether the flag Fb is 1'C- or a cup. When the flag l''b=1r exists, the process proceeds to step 20, whereas when the flag ``b-1'' does not exist, the process proceeds to step 1.

In step 19, the exhaust gas recirculation flow ff1F is increased during idle operation according to the counter value C of the counter.
i is determined, and the flag Fb is changed to it, :. The relationship between the counter value C and))) gas re1F+recirculation Ei is such that, as an example is shown in FIG. 111 in proportion to
Air gas recirculation 1m Ti1t hanging Ei increases, counter h
rj (when C is equal to or greater than the predetermined tirj, the counter f
Regardless of the increase in in C, the exhaust gas recirculation flow IEi remains constant at a maximum of 11n. Also, in step 19, -C:
The counter value C of the counter is set to O. After step 19, the process advances to step 20.

In step 20, it is determined whether a predetermined period ■ has elapsed after the non-idling engine 43 enters the A state, in other words, after the easel engine 111' enters the idling operating state. A determination is made. When a predetermined period of time 1' has elapsed since the related engine 1 entered the idling state, that is, from the start of the idling operation, the process proceeds to step 21.
On the other hand, after the predetermined time period "1-" has elapsed since the start of the idle operation, the process proceeds to step 22.

In step 21, in step 18, a pulse signal of (determined exhaust gas recirculation flow ff1Ei1.: base < predetermined f nity ratio EF, out is output to the negative pressure adjustment valve 29. When the pressure regulating valve 29 is given the pulse signal, it outputs a negative pressure corresponding to the counter I+rjC to the negative pressure output capo 1 30, and the exhaust gas recirculation control valve 11 is driven by this negative pressure. Therefore, at this time, that is, until a predetermined period of time has elapsed since the start of idling, exhaust gas recirculation is performed at a flow rate determined according to the counter value C of the counter, as shown in FIG. Step 21 is followed by a reset.

In step 22, flag switching is performed to change the flag ``a'' to ``O''.The next step after step 21 is step 23.
Proceed to.

In step 23, the duty ratio E of PAL No. 218 is
out is set to 0. That is, an off signal is issued. When the negative 1-1 regulating valve 29 is given an off signal, it no longer outputs a substantial negative pressure to the negative pressure output port 30, which causes the exhaust gas recirculation control valve 11 to close and exhaust gas recirculation to begin. will be stopped. The next step after step 23 is a reset.

By performing control according to the flowchart as described above, the counter IaC of the counter indicates that the i-eel engine 'I is operated at a rotational speed higher than a predetermined value and ■-the fuel injection lift per culm is lower than a predetermined value. Since it is counted up only at certain times and down counted at other times, this counter (exhaust gas recirculation flow rate Ei during idle operation, which is determined according to target C), is When the diesel engine 1 is operated at a high load (i.e., when the engine temperature becomes high, the temperature becomes high, and when the diesel engine 1 is operated at low speed and low negative speed, the engine temperature becomes low). By determining the JJI gas recirculation in this way, the NOx concentration in the IJ1 gas during idling operation can be effectively reduced.

In this embodiment, during the warm-up process when the cooling water shortage of the T-building engine is below a predetermined value, (step 1)
In step 3, the counter lI'iC is set to O, so that no exhaust gas recirculation occurs during the warm-up process during idling operation.

In the flow plays 1 to 2 shown in FIG. Thus, the exhaust gas recirculation time T is determined according to the counter value of the counter.

In this case, the IJI gas recirculation time 1 is shown in FIGS. 6 and 7 (as shown in the counter 60 C
When is large, that is, when the engine temperature is high, it can be set for a long time, and this makes it even more effective to reduce NOx by 1g by 1 degree in exhaust gas during idling without causing low-temperature corrosion. will be carried out.

FIG. 8 shows only the essential parts of another example of a flowchart of a control device for implementing the JJI gas recirculation control method according to the present invention. In this example,
After step 22, proceed to step 24, and step 2
In No. 4, the duty ratio of the pulse signal [: Bt is reduced by ΔE /<G] is used. After step 24, the process proceeds to step 25.

At Sudetsu/25, the duty ratio of the pulse signal Eo
A determination is made as to whether ut is smaller than 0 or not. When the duty ratio of the pulse signal Eout<Q, the process proceeds to step 23, and the duty ratio of the pulse signal Eout<Q.
□If there is no r, proceed to step 26.

In step 26, the pulse signal of the reduced duty ratio [:out] is output to the adjustment valve 29 at the suit tube 23.

By carrying out the control according to the flowchart as described above, as shown in FIG. ° (Defined ICC flow and exhaust gas recirculation,]! Idle operation 1; jl 9f.

After a predetermined period of time has elapsed, the exhaust gas recirculation flow rate decreases by 1 at a predetermined rate of decrease over time, and after a predetermined period of time, the JII gas recirculation is stopped.

In the embodiments shown in FIGS. 8 and 9, C is 1) 1 gas recirculation in which exhaust gas recirculation is performed at a flow rate h/h determined according to the counter value C of the counter. The circulation time is constant, but during this exhaust gas re-V'JIIh period, W! 1
As shown in FIGS. 0 and 11, depending on the counter value C of the counter, the temperature may be set to iiJ in the same manner as in the embodiment shown in FIGS. 5, 7'J to 7.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to these embodiments, and it is understood that various embodiments may be made within the scope of this defense. It will be clear to those skilled in the art.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing one embodiment of a 171 gas recirculation device implementing the exhaust gas recirculation control method according to the present invention; Figure 3 shows the relationship between the counter direction of the counter and the exhaust gas recirculation flow rate during idling operation, and Figure 4 shows an example of the implementation procedure. Figure 5 shows another example of the actual IN weak region of the exhaust gas recirculation control method according to the present invention. Regarding the main parts (Norobe Yard shown, Figure 6 shows the counter) J counter loading and illumination during idling operation.
Figure 7 is a graph showing the relationship between exhaust gas IIj and circulation time, and Figure 8 is a graph showing the change over time in the exhaust gas recirculation raw stone during idling operation in the embodiment shown in Figure 5. 9 is a flowchart 1 showing main parts of another embodiment of the method for controlling exhaust gas recirculation according to the present invention, and FIG. Figure 10 is a graph showing the change over time in the exhaust gas recirculation flow rate during operation. Fig. 11 shows the flow of exhaust gas recirculation during idling operation in the embodiment shown in Fig. 10. It is a graph showing changes over time. 1...Diesel engine, 2...Cylinder bore, 3.
... Piston, 4... Combustion chamber, 5... Vortex chamber, 6.
...Intake manifold, 7...Exhaust boat, 8...
Exhaust bow 1-29...exhaust manifold, 10...
Poppet valve", 11...1 no. 1 gas recirculation control valve,
12...Casing, 13...Entrance boat, 14.
...Exit boat, 15... Conduit. 16... Exhaust gas extraction boat, 17... Conduit, 1
8...4 + gas injection boat, 19...valve element,
20... Foot part, 21... Valve bow 1~. 22・
...Valve rod, 23...Tie
26... Guyanorum chamber, 27... Compression spring,
28... Memory, 29... Negative 11X adjustment valve, 30...
・i I-i: Output capo-1-, 31... Negative pressure input boat, 32... Negative pressure bomb f, 33... Conduit, 40...
・Control device 6゜41... Fuel oil injection IJI lfi, l
! N4, 41...The number of revolutions is low. 1133...Noah, idle switch, 44...Water temperature switch special rl Applicant: I. Yota Automobile Co., Ltd. Agent: jT Ume-1-Akii 3 Masatake Figure 9 Figure 11 Diagram between 0 and -□-

Claims (1)

[Claims] During idle operation, exhaust gas is recirculated for a predetermined period of time from the start of idle operation at a flow rate determined according to the engine operating state before entering the idle operation state, and during operation other than idle operation, the exhaust gas is recirculated at the flow rate determined according to the engine operating state before entering the idle operation state. A method for controlling exhaust gas recirculation for a deep-pill engine, characterized in that exhaust gas is recirculated at a flow rate set at any time depending on the operating state of the engine.