JPS59126019A - Regenerative apparatus of exhaust particulate catching trap in internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the accuracy of judgement for regeneration by a method wherein the judgement for regeneration of a trap is allowed to perform only under the conditions that the rotational speed exceeds a predetermined value and the load is heavier than a predetermined value or under the conditions both the ratios of change of said rotational speed and load are below predetermined values in addition to the above-mentioned conditions. CONSTITUTION:The exhaust gas purifying device of an internal combustion engine consists in catching particulates in exhaust gas by means of a trap 4 arranged in an exhaust gas passage 1. When a control device 23, to which the outputs of respective pressure sensors 21 and 22 on the inlet and outlet sides of the trap 4 are inputted, judges that the difference between pressure before and after the trap 4 is too large to pstpone the regeneration of the trap 4, a burner 5 for regenerating the trap 4 is put into actuation in order to incinerate caught particulates. In this case, a feedback amplifier 36, in which the output signals of an engine rotational speed sensor 31 and of a load sensor 32 are matched each other, is provided in the control device 23 so as to conduct control elements 34 and 35 under the conditions that the rotational speed exceeds a predetermined speed and at the same time the load is heavier than a predetermined load in order to let the control device 23 perform its intrinsic judgement for regeneration.

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 particulates collected in the trap. Based on the pressure difference between the inlet side pressure and outlet side pressure of the trap, the particulate matter in the trap is Detects the collection state,
It determines whether regeneration is necessary and operates the burner if regeneration is necessary.

However, in such conventional control devices for playing card reproducing burners, when determining the clogged state of the trap from the differential pressure across the trap, the exhaust pressure is proportional to the rotational speed and load, so the rotational speed When the load is low, the exhaust pressure is also low. Therefore, in the area shown with diagonal lines in Figure 1, the clogging state may not be accurately determined and wasteful regeneration may be performed. There was a problem that the amount of consumption increased.

In addition, even if the rotation speed is above a predetermined speed, the load is above a predetermined load, and the exhaust pressure is high, there is a delay in the response of pressure (trap inlet side pressure) during acceleration or deceleration. When the change occurs, a deviation occurs between the actual measured value and the calculated value, and as a result, the clogging state cannot be accurately determined, which still causes the above-mentioned problem.

The present invention was made with the aim of solving such conventional problems, and it is based on the signal from the rotation speed sensor and the signal from the load sensor that the load is at a predetermined value when the rotation speed is above a predetermined value. A means is provided to make the regeneration judgment only under the above conditions, or in addition to the above conditions, only when the rate of change in rotational speed and the rate of change in load are each less than a predetermined value, and to stop the regeneration judgment under other conditions. By providing this, the accuracy of playback judgment is improved.

Examples will be described below.

In FIG. 3, a trap case 2 is interposed in the middle of an exhaust passage 1 of a diesel engine, and a honeycomb type trap 4 is installed inside the trap case 2 with a buffer material 3 interposed therebetween. In this trap 4, some of the holes in the honeycomb are opened on the inlet side and the outlet side is closed, and the other portions are closed on the inlet side and the outlet side is opened. This is used to collect 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 its 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. pipe 8 and the flame jetting lower a of the reverse flow type evaporator tube 7 in the combustion tube 6.
It is configured to include a glow plug 9 for ignition facing nearby.

A fuel supply pipe 11 from an electromagnetic fuel injection valve (fuel injector) 10 is connected to the mixture injection pipe 8, and fuel (engine fuel) is supplied to the fuel injection valve 10 from a fuel tank 13 by an electromagnetic fuel pump 14. It is the same as that for example light oil). Further, an air supply pipe 17 is connected to a discharge port 15b of an air pump 15 via an electromagnetic three-way valve 16 in the middle of the fuel supply pipe 11. The three-way valve 16 connects the discharge port 15b of the air pump 15 and the suction port 15a in a non-energized state, and connects the discharge port 15b and the air supply pipe 17 in a energized state.

Therefore, the burner 5 is operated by operating the fuel pump 14, the fuel injection valve 10, the three-way air supply valve 16, and the glow plug 9.

Since the fuel pump 14 is powered by a battery, it is energized via a relay 19 which is turned on and off, and this relay 19 is turned on and off by a signal current from a control device 23, which will be described later. Further, the fuel injection valve 10 and the three-way air supply valve 16 are directly driven by a signal current from the control device 23.

Furthermore, the glow plug 9 is energized from the pantry 18 via a normally open relay 20, which is closed by a signal current from the control device.

Here, the exhaust inlet to the trap 4 (burner 5
An inlet side pressure sensor 21 for detecting the inlet side pressure P+ is provided downstream), and an outlet side pressure sensor 22 for detecting the outlet side pressure P2 is provided at the exhaust outlet from the trap 4. These pressure sensors 21 and 22 receive exhaust pressure through a diaphragm to minimize the influence of exhaust heat on the sensor section, and the sensor section is formed of, for example, a piezoelectric element. In the figure, a potentiometer type is shown. The output voltages VPI and VP2 of these pressure sensors 21 and 22 are controlled by the control device 23.
It is now entered into

Further, a rotation speed sensor 31 for detecting the rotation speed of the engine and a load sensor 32 for detecting the load on the engine are provided. The rotational speed sensor 31 is composed of a crank angle sensor, and the load sensor 32 is composed of a fuel injection pump 33.
It is composed of a potentiometer that rotates in conjunction with the control lever 338. Detection signals from these sensors 31 and 32 are input manually to the control device 23.

The control device 23 mainly receives the output voltage VP+ of the inlet side pressure sensor 21 and sets 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 may and the output voltage Δvp of the differential pressure calculation device 25 are input and compared, Δvp≧ΔV P max
A comparator 26 that emits an H level signal in the case of , and a fuel pump relay 19, fuel injection valve 10, air supply three-way valve 16, and glow plug relay when an H level signal is input from the comparator 26. 20 and an output device 27 that operates the output device 20.

Note that the output device 27 has a built-in constant voltage circuit, and a battery voltage vb is applied from the battery 18 to the power terminal of the output device 27 via the engine key switch 28. In addition, an output device 2 is connected to the power terminals of the limit value calculation device 24, the differential pressure calculation device 25, and the comparison device 26.
From 7 onwards, a constant voltage of 0 is applied.

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 foot hack amplifier 36 which receives detection signals from the rotational speed sensor 31 and the load sensor 32 and makes the control element 34.35 conductive when the rotational speed is above a predetermined rotational speed and the load is above a predetermined load. be done.

FIG. 4 shows a specific example of the configuration of the control device 23.

Here, the limit value calculation circuit 24 is a coefficient unit (multiplier) 24
It consists of a 1° subtractor 242 and a preset 243.

The differential pressure calculation device 25 uses the subtracter 250 to calculate the comparator 26
is determined by the comparator 260, and the output device 27 is connected to the output circuit 2.
70, respectively.

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

350, the feedback up 36 is
An F/V converter 361 to which a rotation speed signal (pulse signal) is input, a comparator 362, a preset 363, a comparator 364 to which a load signal (voltage signal) is input, a preset 365, and an AND circuit. It is composed of 366 and 366 characters.

Next, the action will be explained.

The honeycomb trap 4 has the characteristics of a laminar flow meter.
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 Pl and ΔP
The ratio ΔP/P+ is constant. Of course, the ratio ΔP/PI 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 5 to 10 g),
Output voltage VP of inlet side and outlet side pressure sensor +21.22
If the relationship between the difference Δ■P=VPl−νP2 between + and VP2 is found experimentally, ΔVP (this is called the differential pressure limit value ΔV P max) at the limit S capture amount can be expressed by the following formula. I can do 1 thing.

ΔVPmax −A ・VP I−B (A, B are constants) Based on the above principle, the control device 23 sets the limit collection which is the regeneration condition based on the signals from the inlet side pressure sensor 21 and the outlet side pressure sensor 22. Determine whether the amount has been reached.

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 VP+ of the inlet side pressure sensor 21 is equal to the limit value calculation device 2.
4 and the differential pressure calculation device 25, and 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 coefficient unit 241 multiplies the output voltage VP+ of the inlet side pressure sensor 21 by a constant A, and then a subtracter 242 multiplies the constant B from the preset 243.
by subtracting the predetermined limit value ΔVPmax=A・VP +-
Calculate B. In addition, in the subtracter 250 as the differential pressure calculation device 25, the output voltage V of the inlet side pressure sensor 21 is
The output voltage VP2 of the outlet side pressure sensor 22 is subtracted from P+, and the difference ΔVP-VP+-VP2 is calculated. 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 playback condition, is
1. When P≧ΔV P max, that is, when the differential pressure exceeds the current limit value. Emit an H level signal.

Then, in response to the H level signal from the comparator 26, the output circuit 270 as the output device 27 regenerates the trap 4 by appropriately operating each device for the burner 5 using a built-in timer.

For details, first close the glow plug relay 20,
The glow plug 9 is activated to raise the temperature to the level required for ignition.

After a certain period of time, the air supply three-way valve 16 is operated to start supplying air. At the same time, the fuel pump relay 19
is closed and the fuel pump 14 is operated, and at the same time, the fuel injection valve 10 is operated to start supplying fuel.

As a result, a mixture of fuel and air is ejected from the 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 through the flame outlet 7a. 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 by this combustion heat.

The glow plug 9 is deactivated by opening the glow plug relay 20 after a predetermined time has elapsed since fuel injection.

After a predetermined period of time has elapsed, the operation of the fuel injection valve 10 is stopped, and the fuel pump relay 19 is opened to stop the operation of the fuel pump 14. 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
It is assumed that 0 and 350 are in a conductive state, but these analog switches 340 and 350 are gate switches for determining regeneration only under conditions of a predetermined rotation speed or more and a predetermined load or more, and are controlled by the feedback amplifier 536. As a result, the output voltage V from the pressure sensor 2122
The transmission of PI and VP2 is controlled.

In the feedback amplifier 36, the rotation speed signal (pulse signal) from the rotation speed sensor 31 is converted into a voltage by the F/V converter 361, and compared with a predetermined value (preset 363) by the comparator 362. At this time, the output of the comparator 362 becomes H level. Also, the load signal (voltage signal) from the load sensor 32 is transmitted to the comparator 364.
is compared with a predetermined value (precession l-365), and when the predetermined value or more is greater than the predetermined value, the output of the comparator 364 becomes I] level. The outputs of these comparators 362 and 364 are connected to the AND circuit 3.
66 , the AND circuit 366 connects the comparators 362 .
When the outputs of 364 are both at H level, therefore, when the rotation speed is above a predetermined rotation speed and the load is above a predetermined load, an H level signal is generated.

The H level signal from the AND circuit 366 brings the analog switches 340 and 350 into conduction.

Therefore, the signals from the pressure sensors 21 and 22 are transmitted to the calculation section of the control device 23 to make a regeneration judgment only when the rotation speed is above a predetermined speed and the load is above a predetermined load. Analog switch 340.35
As a result of 0 becoming non-conductive and transmission being cut off, the regeneration decision 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. 5 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,
, a comparison device 26, an output device 27, a control element 34, 35, a feed bank amplifier 36, and a rotation speed sensor +31.
and a load sensor 32, respectively, and a rate-of-change calculation device 38 that calculates the rate of change of each signal. The output terminal of this change rate calculating device 38 is connected to the feed bank amplifier 36, and when the rotation speed and the load change rate are both below a predetermined change rate,
The level signal is sent to a feed bank amplifier 36.

Therefore, the H level is output from the feed bank amplifier 36 only when all four conditions are satisfied: the rotation speed is above a predetermined value, the load is above a predetermined value, the rate of change in rotation speed is below a predetermined value, and the rate of change in load is below a predetermined value. A signal is emitted and the control element 34. 'a5 becomes conductive and regeneration judgment is made; otherwise, regeneration judgment is stopped.

Next, an example of the configuration of the control device 23 of this embodiment using a microcomputer will be explained. FIG. 6 shows the hardware configuration in that case, and FIG. 7 shows a program flowchart.

Referring to FIG. 6, 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.
22 (7) Output voltage VP +, VP 2, the detection signal from the rotational speed sensor 31 inputted via the F/V converter 361, and the detection signal from the load sensor 32, one of which is selectively set to A. A multiplexer 44 for inputting the /D converter 430, and a PIO (peripheral l10) 45 for interfacing the CPU 41 with the A/D converter 43, multiplexer 44, and output circuit 270 are required.

Note that the CPU 41 issues a channel instruction to the multiplexer 44 and a start instruction to the A/D converter 43 via the PI045, and receives an EOC (End of Convert) signal from the A/D converter 43 indicating the end of conversion. After receiving the data, the user is prompted to input the digitally converted data.

The hardware side only performs input/output operations, and comparison with predetermined values, calculation of rotational speed and rate of change in load, and comparison are all performed by software.

The flowchart will be explained with reference to FIG.

The registers R1 and R2 are cleared in S1, the rotational speed is read in S2, and it is determined in S3 whether or not it is greater than a predetermined value. If the judgment in S3 is NO, return to Sl and select YE.
In the case of S, the process advances to 34 and the value is stored in register R1.

After S4, the process advances to S5 to read the engine load, and in S6 it is determined whether or not it is greater than a predetermined value. If the determination in S6 is No, the process returns to Sl, and if it is YES, the process proceeds to 87, where the value is stored in register R2.

After S7, proceed to S8, and after a certain period of delay, proceed to S9.
The engine speed is read again at SIO, and the rate of change is calculated by comparing the value at that time with the value stored in register R1 at SIO, and it is determined at Sll whether the rate of change is less than a predetermined value. If the judgment in Sll is NO, return to Sl and Y
In the case of ES, the process advances to the next step 312. In S12, the engine load is read again, and in S13, the rate of change is calculated by comparing the value at that time with the value stored in register R2, and in S14
Then, it is determined whether the rate of change is less than or equal to a predetermined value. S14
If the determination is No, the process returns to Sl, and if it is YES, the process proceeds to the next step 315.

In this way, the rotation speed is above a predetermined value, the load is above a predetermined value,
Only when the four conditions, ie, the rate of change in rotational speed is less than a predetermined value and the rate of change in load is less than a predetermined value, does the process proceed to S15, where a regeneration determination is made.

Regeneration judgment is verified by inputting the trap inlet side pressure and outlet side pressure, but if it is determined that the regeneration conditions are met here, S16
Go to and activate the burner for a predetermined time to regenerate the trap.

Note that the hardware configuration is exactly the same, and by partially deleting the flowchart, it can be easily adapted to the embodiment shown in FIG.

As explained above, according to the present invention, a regeneration judgment is made only under the conditions that the rotational speed is above a predetermined value and the load is above a predetermined value, or in addition, the rate of change of both of them is below a predetermined value. Since the regeneration judgment is stopped under conditions other than those where it is likely to occur, the accuracy of the regeneration judgment is improved, and the consumption of burner fuel due to wasteful regeneration can be prevented.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams for explaining conventional problems,
FIG. 3 is a configuration diagram showing one embodiment of the present invention, and FIG.
A block diagram showing a specific configuration example of the control device in the figure,
FIG. 5 is a configuration diagram showing another embodiment, FIG. 6 is a block diagram showing a hardware configuration when the microcomputer of the control device in FIG. 5 is used, and FIG. 7 is a flowchart of the same. l...Exhaust passage 4...Trap 5...Burner 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 pump 16... Three-way valve 21... Inlet side pressure sensor 22... Outlet side pressure sensor 2
3...Control device 24...Limit value calculation device 2
5... Differential pressure calculation device 26... Comparison device 27...
・Output device 31... Rotation speed sensor 32...
・Load sensor 34, 35...control element 36・
...Feedback amplifier 38... Rate of change calculation device Patent applicant Fujio Sasashima, Patent attorney, Nissan Motor Co., Ltd.

Claims (1)

[Claims] +1) A trap provided in the exhaust passage to collect particulates in the exhaust gas, a trap regeneration burner for incinerating the particulates collected in the trap, and an inlet side pressure and an outlet of the trap. In an internal combustion engine equipped with a control device that detects the state of particulate collection based on the side pressure, determines whether regeneration is necessary, and controls burner operation, the engine includes a rotation speed sensor that detects the rotation speed of the engine, and a load on the engine. In addition, based on the signals from these sensors, a regeneration judgment is made only under conditions where the rotation speed is above a predetermined value and the load is above a predetermined value, and under other conditions, the regeneration judgment is made. 1. A regeneration device for a trap for collecting exhaust particulates in an internal combustion engine, characterized in that a means for stopping the trap is provided. (2) A trap installed in the exhaust passage to collect particulates in the exhaust gas, a trap regeneration burner to incinerate the particulates collected in the trap, and particulates collected from the inlet and outlet pressures of the trap. A rotation speed sensor that detects the engine rotation speed and a load sensor that detects the load of the engine. In addition, based on the signals from these sensors, the conditions are determined such that the rotational speed is at least a predetermined value, the load is at least a predetermined value, and the rate of change in the rotational speed is at least a predetermined value and the rate of change in the load is at least a predetermined value. 1. A regeneration device for a trap for collecting exhaust particulates in an internal combustion engine, characterized in that a regeneration device is provided for making a regeneration determination only under conditions and stopping the regeneration determination under other conditions.