JPS59128912A - Regenerative apparatus for exhaust particle collecting trap in internal-combustion engine - Google Patents

Abstract

PURPOSE:To make an accurate regeneration judgeable, by letting a control unit judge the regeneration only when pressure at the exhaust inlet side of a particle trap to be set up in an exhaust pipe line of a Diesel engine goes beyond the specified value. CONSTITUTION:A burner 5 to which a glow plug 9 and an air-fuel mixture injection pipe 8 are connected is installed in the upstream side of a particle trap 4 to be set up in an exhaust pipe line of a Diesel engine. In a space between the trap 4 and the burner 5, there are provided with an inlet side pressure sensor 21 for detecting an exhaust inlet side pressure P1 and an outlet side pressure sensor 22 for detecting an outlet side pressure P2 at an exhaust outlet part from the trap 4. A detected value VP1 of the inlet side pressure sensor 21 is inputted into a comparator 36 of a control unit 23, and only when this detected value goes beyond the specified value, each of control elements 34 and 35 are turned on, making the control unit 23 perform a regenerative judgement on the basis of each of detected values VP1 and VP2 of these inlet and outlet side sensors 21 and 22.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a regeneration burner of an exhaust particulate trap used as an exhaust purification device for an internal combustion engine.

As a conventional exhaust gas purification device for an internal combustion engine for an automobile, there is one disclosed in, for example, Japanese Patent Laid-Open No. 115809/1983. This is done by setting up a trap in the middle of the exhaust passage to collect particulates whose main component is carbon in the exhaust.
It is also equipped with a trap regeneration burner that incinerates the fine particles collected in the trap, and the fine particles in the trap are Detects the collection state,
It determines whether regeneration is necessary and operates the burner if regeneration is necessary.

However, in such conventional trap regeneration burner control devices, the exhaust pressure is constantly detected.
Since the regeneration judgment was made, the accuracy of the regeneration judgment was poor in the low speed/low load range where exhaust pressure is low, and unnecessary regeneration may be performed due to recreational judgment, which increases burner fuel consumption. There was a problem with that.

Further, during sudden acceleration or sudden deceleration, accurate regeneration judgment cannot be made due to a delay in pressure response, and the above-mentioned problems also occur in this case.

The present invention has been made with the aim of solving these conventional problems.Based on the signal from the pressure sensor installed at the exhaust inlet of the trap, the present invention detects the trap when the pressure at the trap inlet exceeds a predetermined value. The accuracy of the regeneration judgment can be improved by providing a means to make the regeneration judgment only under the condition that the change rate of the pressure at the trap inlet side is equal to or less than a predetermined value, and to stop the regeneration judgment under other conditions. It has been improved.

Examples will be described below.

In FIG. 1, a trap case 2 is interposed in the middle of an exhaust passage 'l of a diesel engine, and a honeycomb type trap 4 is installed inside the trap case 2 with a buffer material 3 interposed therebetween. This trap 4 has an inlet (JI + J t-) for some of the honeycomb holes and closes the outlet side, and for the other part, the inlet side is closed and the outlet side is open.
When the exhaust gas passes through the wall of the hole, it collects fine particles.

A burner 5 for trap regeneration is provided upstream of the trap 4 in the trap case 2.

The burner 5 includes a combustion tube 6 having a large number of exhaust gas introduction holes 6a on the peripheral wall, a backflow type evaporator tube 7 located inside the combustion tube 6 and having a flame jetting lower a, and a mixture jet facing into the backflow type evaporator tube 7. It is composed of a tube 8 and a glow plug 9 for ignition, which faces the vicinity of the flame jetting lower a of the reverse flow type evaporator cylinder 7 during combustion @ 61'i.

The mixture injection pipe 8 is connected to a fuel supply pipe 11 from an electromagnetic fuel injection valve (fuel injector) 10 (connected to the fuel tank 13), and an electromagnetic fuel pump 14 supplies fuel ( It is the same as engine fuel, such as light oil), and G is controlled so that it is guided. Further, in the middle of the fuel supply pipe 11, there is a discharge port 15b of the air d5 valve 15.
An air supply pipe 17 is connected to the air supply pipe 17 via an electromagnetic three-way valve 16. When the three-way valve 16 is de-energized, the discharge port 15b of the air pump 15 and the suction port 15a are connected, and when the three-way valve is energized, the discharge port 15b and the air supply pipe 17 are connected.

Therefore, the operation of the burner 5 is controlled by the fuel pump "14,
This is done by operating the fuel injection valve 10, the three-way air supply valve 16, and the aperture plug 9.

The fuel pump 14 is energized from the battery through a 1-line 19 that is opened and closed, and this IJ relay 9 is closed by a signal current from a control device n, which will be described later. . Further, the fuel injection valve 10 and the three-way air supply valve 16 are directly driven by the current from the control device 1 and the like, so that the current is I+'.

Furthermore, the glow plug 9 is energized via the normally open relay 20, which relay 20 is energized by a signal current from the control device.

It is now closed.

Here, a population pressure P1 for detecting the population side pressure P1 is set at the exhaust inlet part (-Nana-5 flow) to the tiger knob 4.
A pressure sensor 21 is provided, and an outlet side pressure sensor 22 for detecting an outlet side pressure P2 is provided at the exhaust outlet portion of the tiger knob 4 force 1 and the like. These pressure sensors 21, 22
By receiving exhaust pressure through a diaphragm, the influence of exhaust heat on the sensor section is minimized, and the sensor 1 is composed of, for example, a piezoelectric element. The figure shows a potentiometer type. And the pressure sensor 21.22 (7) output voltage VP
+, VPzL; 1: t#I is designed to be input to the control device.

The control device 23 mainly controls the output voltage VP+ of the inlet side pressure sensor 21 to a predetermined limit value (ΔV P max
), a differential pressure calculation device 25 which receives the output voltage VP+ of the inlet side pressure sensor 21 and the output voltage VP2 of the outlet side pressure sensor 22 and calculates the difference (ΔVP) between them; Output voltage Δ of limit value calculation device 24
V P max and the output voltage Δvp of the differential pressure calculation device 25 are input and compared, Δ■P≧ΔV P wax
A comparator 26 that emits an H level signal in the case of , and a fuel pump relay 19, a fuel injection valve IO1 air supply three-way valve 16, and a glow plug relay 20 when an H level signal is input from the comparator 26. and an output device 27 that operates the .

The output device 27 has a built-in constant voltage circuit, and the battery voltage vb is applied to the power terminal of the output device 27 from the engine via the engine key switch 28. In addition, an output device 27 is connected to the power terminals of the limit value calculation device 24, the differential pressure calculation device 25, and the comparison device 26.
A constant voltage Vo is applied from .

Furthermore, the control device 23 is a control element that is interposed in a signal system between the inlet side pressure sensor 21, the outlet side pressure sensor 22, the limit value calculation device 24, and the differential pressure calculation device 25, and opens and closes the signal system. 34, 35, and a feedback amplifier 36 which inputs the output voltage VP+ of the inlet force sensor 21 and makes the control element 34, 35 conductive when the inlet pressure P1 is equal to or higher than a predetermined value. Note that this feedback amplifier 36 also receives a constant voltage Vo from the output device 27.
is applied.

FIG. 2 shows a specific example of the configuration of the control device 23.

Here, the limit value calculation circuit 24 is a coefficient unit (multiplier > 2
It consists of a 41° subtracter 242 and a preset 243.

The differential pressure calculation device 25 uses the subtracter 250 to calculate the comparator 26
are each configured by a comparator 260.

The output device 27 includes a timer 271, a delay circuit 272,
It consists of a timer 274, etc., and a comparator 26σ in the previous stage.
The output is input to a timer 271 and a delay circuit 272. The timer 271 is connected to a switch circuit 273, and the timer 271 and the switch circuit 273 constitute an output circuit for a glow plug. Delay circuit 272 is connected to a timer 274, which is connected to switch circuit 275, switch circuit 276, and the gate terminal of case 1-277.

Here, the delay circuit 272, timer 274, and switch circuit 275 constitute an output circuit for a three-way valve, and the delay circuit 272, timer 274, and switch circuit 276
The output circuit for the fuel pump is constructed by the above. Further, an oscillator 278 is connected to the input terminal of the gate 277, and an output terminal of the gate 277 is connected to the amplifier circuit 279.
As a result, an output circuit for the fuel injection valve is configured including the delay circuit 272, timer 274, cable 1-277, oscillator 278, and amplifier circuit 279.

Further, the control elements 34 and 35 include analog switches 34o and 34o.
.

350, the feedback up 36 is
It is composed of a comparator 362 and a preset 362.

Next, the effect will be explained.

The honeycomb type trap 4 has the characteristic of laminar flow rate side.
If the amount of collected exhaust particles is constant, the trap inlet pressure P+ (proportional to the gas amount) and the differential pressure between the inlet and outlet pressures ΔP-P + -P2 are linearly proportional, and PI and ΔP
The ratio ΔP/P+ is constant. Of course, the ratio ΔP/P+ increases as the amount of trapped water increases.

Therefore, the output voltage ■P1 of the inlet side pressure sensor 21 when the amount of collection reaches the limit (for example, about 8 g), and the output voltage VP + of the inlet side and outlet side pressure sensors 21.22,
If the relationship between VP2 difference ΔVP=VPI VP2 is determined by experiment, ΔVP at the limit collection amount (this is referred to as differential pressure limit value ΔV P max) can be expressed by the following equation.

ΔVPmax ”A ・VP + −B (A, B
is a constant) Based on the above principle, the control device 23 determines whether or not the limit collection amount, which is a regeneration condition, has been reached based on the signals from the inlet side pressure sensor 21 and the outlet side pressure sensor 22.

That is, assuming that the analog switches 340 and 350 as the control elements 34 and 35 are in a conductive state, the output voltage P1 of the inlet side pressure sensor 9-21 is input to the limit value calculation device 24 and the differential pressure calculation device 25. , the output voltage VP2 of the outlet side pressure sensor 22 is input to the differential pressure calculation device 25.

In the limit value calculating device 24, first, a constant A is applied to the output voltage VP1 of the inlet side pressure sensor I-21 using a coefficient unit 241.
Then, the subtracter 242 subtracts the constant B from the preset 243 to obtain "ζ, a predetermined limit value ΔVPmax=AV
Calculate P+B. Further, the subtracter 250 serving as the differential pressure calculating device 25 subtracts the output voltage VP2 of the outlet side pressure sensor 22 from the output voltage VP+ of the inlet side pressure sensor 21, and calculates the difference Δ■P−■PIVP2. Here, ΔV P max corresponds to the differential pressure at the limit collection amount, and Δvp corresponds to the actual differential pressure.

Then, in the comparator 260 as the comparison device 26, ΔV
P max and Δvp are compared, and Δv, which is the reproduction condition, is
When p≧ΔV P max, that is, when the differential pressure exceeds the current limit value, the I] level signal is generated.

Then, based on the H level (8%) from the comparison device 1, the output device 27 appropriately operates each device for the burner 5 to regenerate 1-lap 4.

For details, refer to Quimchar 1 in FIG. 3. First, for a time T1 specified by the timer 271, the glow plug relay 20 is closed, the glow plug 9 is activated, and the temperature required for ignition is increased. rise to.

After delaying the time T2 specified by the delay circuit 272 from the start of operation of the glow plug 9, the three-way air supply valve 16 is operated to supply air for a time T3 specified by the timer 274, and at the same time the fuel pump relay is activated. 19 is closed to operate the fuel pump 14, and at the same time, the fuel injection valve IO is operated to supply fuel. At this time, the fuel injection valve 10 is activated by the oscillator 27 by opening the case I~277.
It is driven at a cycle of 8. Furthermore, T 2 < T
+<T2+T:l.

As a result, a mixture of fuel and air is ejected from the air-fuel mixture jet pipe 8 of the burner 5, flows through the reverse flow type evaporator cylinder 7, and is sent into the combustion cylinder 6 from the flame jet lower a. At this time,
It is ignited by the heat of the glow plug 9. Then, it is mixed with the exhaust gas introduced from the many exhaust gas introduction holes 6a of the combustion tube 6, and is combusted by the surplus oxygen in the exhaust gas. Then, the exhaust particulates collected in the downstream trap 4 are combusted and disposed of by this combustion heat.

The glow plug 9 is deactivated by opening the glow plug relay 20 after 1.1 hours have elapsed.

Then, after T 2 + T 3 hours, the fuel injection valve 1
0 is stopped, and the fuel pump relay 19
is opened and the operation of the fuel pump 14 is stopped.

Furthermore, the three-way valve 16 is also switched and the supply of air is also stopped. This ends the playback.

Now the analog switch 34 as control element 34.35
0 and 350 are assumed to be in a conductive state, these analog switches 340 and 350 are gate switches for making a regeneration judgment only when the inlet side pressure PI is equal to or higher than a predetermined value, and are controlled by the feedback amplifier 36. As a result, the output voltage VPI from the pressure sensor 2L 22,
The transmission of VP2 is controlled.

In the feedback amplifier 36, the output voltage VP+ from the inlet side pressure sensor 21 is compared with a predetermined value (present 362) by a comparator 361, and when it is equal to or higher than the predetermined value, the output of the comparator 361 becomes I] level.

Then, the H level signal from the comparator 361 turns on the analog switches 340 and 350.

Therefore, only when the inlet side pressure P1 is above a predetermined value, the signal from the pressure sensor 21.22 is transmitted to the calculation section of the control bag W23 to determine the regeneration, and when it is less than the predetermined value, the analog switch 340.350 becomes non-conductive and the transmission is cut off, and as a result, the regeneration judgment is stopped.

Note that the control device 23 of this embodiment can also be realized by a configuration using a microcomputer, which will be described later.

FIG. 4 shows another embodiment.

In this embodiment, the regeneration judgment is stopped even during sudden acceleration and sudden deceleration, thereby further improving accuracy.

Therefore, only the control device 23 is different, and this control device 23 includes a limit value calculation device 24, a differential pressure calculation device 25,
, the comparator 26, the output device 27, the control element 34, 35, and the feedback amplifier 36, as well as the inlet side pressure sensor 2.
1, and includes a change rate calculation device 3B that receives the output voltage VP+ from 1 and calculates the rate of change. The output terminal of this change rate calculating device 3B is connected to a feedback amplifier 36, and the output voltage VP of the inlet side pressure sensor 21 is
When the rate of change of + is less than a predetermined rate of change, an I (level signal (Vo)) is sent to the feedback amplifier 36.

Therefore, only when two conditions are satisfied: the inlet pressure P1 is above a predetermined value, and the rate of change of the inlet pressure P1 is below a predetermined value, the foot hack amplifier 36 issues an H level signal, and the control elements 34, 35 conducts, and a regeneration judgment is made; otherwise, the regeneration judgment is stopped.

Next, an example of the configuration of the control bag W23 of this embodiment using a micro combinator will be explained. FIG. 5 shows the hardware configuration in that case, and FIG. 6 shows a program flowchart.

Referring to FIG. 5, the hardware configuration includes a CPU 41, a memory 42, an A/D converter 43 for converting analog data into digital data, two pressure sensors 21.
Selectively set one of the 22 output voltages VPI and VP2 to A.
A/D converter 430 input multiplexer 44, and a PIO for interfacing the CPU 41 with the A/D converter 43, multiplexer 44, and output device 27.
(Peripheral l10) 45 is required.

The CPIJ 41 sends a channel instruction to the multiplexer 44, a star [1] signal to the A/D converter 43, and an EOC (End of Convert) indicating the end of conversion from the A/D converter 43 via the PI045. After receiving the signal, digitally converted data is input.

The hardware side only performs input/output operations, and the comparison of the inlet side pressure with a predetermined value, the calculation of the rate of change of the inlet side pressure, and the comparison are all performed by rough 1-ware.

The flowchart will be explained with reference to FIG. '6.

Read the output voltage VP+ corresponding to the inlet side pressure with S1, and
is stored in register A. After delaying for a certain period of time in S3, VP+ is read again in S4, and stored in register B in S5. Then, in S6 IA-Bl (rate of change)
It is determined whether or not is less than or equal to a predetermined value. If the determination in S6 is NO, the process returns to Sl, and if the determination is YES, the process proceeds to 87.

In S7, it is determined whether B is greater than or equal to a predetermined value. S
If the determination in step 7 is NO, the process returns to Sl, and if the result is YES, the process proceeds to 88.

In this way, only when two conditions are satisfied, that is, the rate of change of the inlet side pressure is less than a predetermined value and the inlet side pressure is more than a predetermined value, the process advances to S8, and a regeneration determination is made in S8. Regeneration determination is made by inputting the trap inlet side pressure and outlet side pressure, and if it is determined that the regeneration conditions are satisfied, the process advances to S9 and the trap is regenerated by operating the burner for a predetermined period of time.

As explained above, according to the present invention, the regeneration judgment is made under the condition that 1-the lamp inlet side pressure is above a predetermined value, or in addition to this, the rate of change is below a predetermined value, thereby preventing erroneous judgments. Since the playback judgment is stopped under other easy conditions, the accuracy of the playback judgment is improved and the problem caused by unnecessary playback is reduced.
- An effect can be obtained in that fuel consumption can be prevented.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
4 is a block diagram showing a specific configuration example of the control device, FIG. 3 is a time chart of the output device in FIG. 2,
FIG. 4 is a block diagram showing another embodiment, FIG. 5 is a block diagram showing the hardware configuration when using a micro:1 viewer of the control device in FIG. 4, and FIG. 6 is a flow chart of the same as above. It is. ■...Exhaust passage 4...Trap 5...B
-ner 6... Combustion tube 7... Backflow type evaporator tube
8...Mixture jet pipe 9...Glow plug
10...Fuel injection valve 14...Fuel pump 1
5... Air bomb 16... Three-way valve 21... Inlet L1 side pressure sensor 22... Outlet side pressure sensor
Edict...control device 24...limit value calculation bag fi! i'
25... Differential pressure calculation device 26... Comparison device 27.
...Output device 34.35...Control element 36...
Feedback amplifier 38... Rate of change calculation device patent applicant Fujio Sasashima, agent of Nissan Motor Co., Ltd., patent attorney

Claims (1)

[Claims] A trap provided in an ill exhaust passage to collect particulates in the exhaust gas, a trap regeneration burner for incinerating the particulates collected in the trap, and an exhaust inlet and outlet part of the trap. A pressure sensor is installed to detect the exhaust pressure, and based on the signals from these pressure sensors, the trap inlet side pressure and outlet side pressure are used to detect the state of particle collection and determine whether regeneration is necessary. In an internal combustion engine, regeneration is determined only when the trap inlet pressure is equal to or higher than a predetermined value, based on a signal from a trap inlet pressure sensor, and regeneration is determined under other conditions. 1. A regeneration device for a trap for collecting exhaust particulates in an internal combustion engine, characterized in that a means for stopping judgment is provided. (2) A trap installed in the exhaust passage to collect particulates in the exhaust, a trap regeneration burner to incinerate the particulates collected in the trap, and a trap installed at the exhaust inlet and outlet of the trap. Based on the pressure sensor for detecting exhaust pressure and the signals from these pressure sensors, the state of particle collection is detected from the trap inlet side pressure and outlet side pressure, determines whether regeneration is necessary, and controls burner operation. In an internal combustion engine equipped with a control device that performs regeneration, the trap inlet pressure is greater than or equal to a predetermined value and the rate of change in the trap inlet pressure is less than or equal to a predetermined value, based on a signal from the lap inlet pressure sensor. 1. A regeneration device for a trap for collecting exhaust particulates in an internal combustion engine, characterized in that a means is provided for making a judgment and stopping the regeneration judgment under other conditions.