JPS59134316A - Regenerating burner controller for exhaust particle collecting trap in internal-combustion engine - Google Patents

Abstract

PURPOSE:To make the completion of the regeneration work in a trap judgeable with certainty, by stopping the operation of a regenerating burner when the ratio of pressure between the inlet and outlet sides of the particle collecting trap during exhausting comes down to below the specified value. CONSTITUTION:At an exhaust passage 1 in a Diesel engine, there is provided with a trap 4 which collects particles in exhaust gas, and a burner 5 burning up these particles collected by the trap 4 and a glow plug 9 both are installed in a combustion cylinder 6 at the upstream side. Detection values out of an inlet side pressure sensor 18, an outlet side pressure sensor 19, a revolution sensor 20, a load sensor 21, etc., are all inputted into a controller 25. When this controller 25 judges the regenerating timing of the trap 4, it operates a fuel injection valve 10 for the burner 5 and the glow plug 9 and judges that the regeneration is finished when the ratio of pressure between the inlet and outlet sides of the trap comes down to below the specified value, thereby stopping all operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a burner for regeneration of an exhaust particulate trap used as an exhaust gas purification device for an internal combustion engine, and in particular a control device for controlling a regeneration burner after operating the burner and starting regeneration. The present invention relates to a means for stopping the operation of the burner.

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 or not regeneration is necessary, and if regeneration is required, the burner is operated for a predetermined period of time.

By the way, in such a conventional trap regeneration burner control device, the trap is regenerated by opening the burner at a predetermined time.In other words, the trap is regenerated by operating the burner. After that, the completion of playback was determined based on the passage of time.

However, there are differences in the degree of regeneration due to variations in the collected amount and burner combustion temperature, and specifying the -rate in terms of time poses problems in terms of fuel consumption, drivability, etc.

The present invention addresses these points and accurately determines the completion of regeneration using IQ.
The purpose is to make the iL stop the burner operation at an appropriate time.

To achieve this objective, we focused on the fact that the exhaust pressure P during regeneration (during burner operation) is expressed by the following equation.

P=PL+Pp+Pa+Pb pt:) Increase in exhaust pressure due to installing the wrap Pp:
Pt, Pa, and Pb are Although it changes depending on the engine operating conditions, it has no relation to the progress of regeneration and is determined by the engine operating conditions and atmospheric conditions. On the other hand, Pp
Since this is determined by the amount of trapped particles, it can be used to detect the regeneration status of the trap.

Therefore, the progress of regeneration is detected using pressure sensors provided at the exhaust port and outlet of the trap, and at this time, the i-lap port side pressure P1 and the outlet side pressure P2 are As it changes as shown in the figure, the ratio I
When P + /P 2 falls below a certain value, it is determined that regeneration is complete and the burner operation is stopped.

Therefore, in the present invention, after the burner starts operating, the trap inlet side pressure P1 and the outlet side pressure P
A means is provided for calculating the ratio P 1 / P 2 between the burner and the burner and stopping the operation of the burner when this ratio becomes equal to or less than a predetermined value.

Examples will be described below.

In FIG. 2, 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 exit side is closed, and the other holes are closed on the artificial side and the exit side is closed. When the exhaust gas passes through the wall of the hole, it collects particulates.

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 conduit facing into the backflow type evaporator tube 7. 8, and a glow plug 9 for ignition that faces the vicinity of the flame jetting lower a of the reverse flow type evaporator tube 7 within the combustion tube 6.

An electromagnetic fuel injection valve (fuel injector) 0 is provided at the inlet of the mixture conduit 8, and a fuel injection valve 10
Fuel (same as engine fuel, for example, light oil) is introduced from a fuel tank 11 by an electromagnetic fuel pump 12. Further, a discharge port 13b of an air pump 13 is connected to the middle of the air-fuel mixture conduit 8 via an electromagnetic three-way valve 14. The three-way valve 14 connects the discharge port 13b of the air pump 13 and the suction port 13a when it is not energized, and connects the discharge port +3b and the mixture conduit 8 when it is energized.

Therefore, the burner 5 is operated by operating the fuel pump 12, the fuel injection valve jO1, the three-way air supply valve 14, and the glow plug 9.

The fuel pump 2 is supplied with electricity from a battery 15 via a relay 16 between the rooms, and this relay 16 is closed by a signal current from a control device 23, which will be described later. Further, the fuel injection valve lO and the three-way air supply valve 14 are directly driven by a signal current from the control device 23.

Furthermore, the glow plug 9 is a relay from the battery 15! The relay 17 is arranged to be energized via the relay 7, and the relay 17 is closed by a signal current from the control device 23.

Here, the exhaust inlet to the trap 4 (burner 5
An inlet pressure sensor 18 is provided downstream) to detect the inlet pressure P1, and an outlet pressure sensor 19 is provided at the exhaust outlet from the trap 4 to detect the outlet pressure P2. These pressure sensors 1.8. '19 is designed to minimize the influence of exhaust heat on the sensor section by receiving exhaust pressure through the diaphragm.
The sensor section is composed of, for example, a piezoelectric element. In the figure, a potentiometer type is shown. And these pressure sensors 18. The +9 output voltages VPI and VP2 are input to the control device 23.

Further, a rotation speed sensor 20 for detecting the rotation speed of the engine and a load sensor 21 for detecting the load on the engine are provided. The rotation speed sensor 20 is composed of a crank angle sensor, a load sensor 21 and a fuel injection pump 22.
It is composed of a potentiometer that rotates in conjunction with the control lever 222. The signals from these sensors 20 and 21 are input to the control device 23.

As shown in FIG. 3, the control device 23 includes a regeneration time detection circuit 31 that detects whether or not it is the regeneration time (limit collection amount) and issues a regeneration start signal when the regeneration time has come; An output circuit 32 that operates each device for the burner 5 when receiving a regeneration start signal from the timing detection circuit 31, and a regeneration stop circuit 33 that detects the completion of regeneration after the start of regeneration and issues a regeneration stop signal to the output circuit 32. It consists of:

Here, the regeneration timing detection circuit 31 is connected to the inlet side pressure sensor 1.
(VP 1 - VP 2)/VP + is calculated from the output voltage P1 of 8 and the output voltage VP2 of the outlet side pressure sensor 19, and when this is greater than a predetermined value, it is determined that it is time for regeneration and a regeneration start signal is issued. It looks like this.

The output circuit 32 has a built-in delay circuit, etc., and when the burner 5 is activated, the glow plug relay 1 is first activated.
7 is activated, and then the three-way air supply valve 14, the fuel pump relay 16, and the fuel injection valve 10 are activated. The fuel injection amount is controlled by outputting a drive signal with a predetermined pulse width depending on the rotational speed and load.

The reproduction stop circuit 33 includes a divider 34. It consists of a comparator 35 and a preset 36, and calculates VPI/VP2 from the output voltage VP+ of the inlet side pressure sensor 18 and the output voltage VP2 of the outlet side pressure sensor 19, and compares this with a preset value Vc (predetermined value). , when VPI/VP2≦Vc, a reproduction stop signal is generated.

Note that since January 5, battery voltage vb has been applied to the control device 23 via the engine key switch 24.

Next, the effect will be explained.

The honeycomb trap 4 has the characteristics of a laminar flow meter, and if the amount of collected exhaust particulates (flow path resistance) is constant, the pressure on the trap inlet side P+ (proportional to the gas amount) and the population side pressure The differential pressure P+-P2 between P1 and the outlet side pressure P2 is linearly proportional, and their ratio (P+-P2)/PI is constant.

Of course, the ratio increases as the amount of collected water increases.

Therefore, the regeneration timing detection circuit 31 of the control device 23,
From the output voltage VPl of the inlet side pressure sensor 1st and the output voltage VP2 of the outlet side pressure sensor 19, (■P1-VP2)
/VPI is calculated, and it is determined whether this is greater than a predetermined value, that is, whether the limit collection amount has been reached and it is time for regeneration.

As a result, when it is determined that it is the regeneration time, the regeneration time detection circuit 31 issues a regeneration start signal, and the output circuit 32 appropriately operates each device for the burner 5 to regenerate the trap 4.

In detail, first close the glow plug relay 17,
Activate the claw rack 9 and raise the temperature to 4. required for ignition.

After a certain period of time, the air supply three-way valve 14 is operated to start supplying air. At the same time, the fuel pump relay 16
is closed and the fuel pump 12 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 air-fuel mixture conduit 8 of the burner 5, flows through the reverse flow type evaporator cylinder 7, and is sent into the combustion cylinder 6 from its flame jet lower a. At this time, the heat of the glow plug 9 ignites. And burn fif
It is mixed with the exhaust gas introduced from the large number of exhaust gas introduction holes 6a of the i6, and is combusted by excess oxygen in the exhaust gas. Then, the exhaust particulates collected in the downstream trap 4 are combusted by this combustion heat.

At this time, the fuel injection valve 10 is operated by a drive signal that is output from the output circuit 32 and corresponds to the rotational speed and load at that time, and the fuel injection amount is in accordance with the rotational speed and load. Specifically, the fuel injection amount is proportional to the rotational speed and inversely proportional to the load, so that the trap angle [-1/IIL degree] is controlled to be almost constant regardless of changes in the rotational speed and load.

The glow plug 9 is deactivated by opening the glow plug relay 17 after a predetermined time has elapsed since fuel injection. During such regeneration, the regeneration stop circuit 33 of the control device 23 controls the output voltage VP+ of the inlet side pressure sensor 8. From the output voltage VP2 of the outlet side pressure sensor ■9, V P + / VP
2 is calculated and its changes are monitored. And V.P.
When + /V P 2 becomes less than a predetermined value, it is determined that the reproduction is complete and a reproduction stop signal is issued.

As a result, the operation of the fuel injection valve 10 is stopped via the output circuit 32, the fuel pump relay 16 is opened, and the operation of the fuel pump I2 is stopped, and the three-way valve 14 is further switched to remove the air. The supply is also stopped and regeneration ends.

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

CPU 41, memory 42 and interface PI
In addition to the O (peripheral l10) '43, the input terminal includes an A/D converter 44 that converts analog data into digital data, and an A/D converter 44 that selectively converts one of the plurality of input signals into digital data. A multiplexer 45 is provided as an input.

The human power signal is the output voltage VP+ of the inlet side pressure sensor 18,
Output voltage VP 2 of outlet side pressure sensor 19, rotation signal (rotation pulse) of rotation speed sensor 20, and load sensor 21
load signals (analog voltages), and these are input to the multiplexer 45. However, in order to convert the rotation signal into an analog voltage, it is passed through the F/V converter 46. Input to I-45.

The CPU 41 connects the multiplexer 4 via the PI043.
5, a start instruction to the A/D converter 44, and after receiving an EOC (End of Convert) signal without indicating the end of conversion from the A/D converter 44, digital conversion begins. The data entered will be entered.

The CPU 41 operates according to a program based on the flowchart shown in FIG. This flowchart will be described below.

On the output side, switch circuits 47, 48, and 49 are provided for operating the claw plug relay 17, air supply three-way valve 14, and fuel pump relay 16, respectively, in response to output commands from the CPU 41 via the PI 043.

Further, in order to operate the fuel injection valve 10 and control the pulse width of the drive signal (duty control), a triangular wave oscillator 5o, a cassette 51, a D/A converter 52, and a comparator 5 are used.
3 and an amplifier 54 are provided. Here, the gate 51 functions to open in response to an output command via the PI043 and input the output of the triangular wave oscillator 50 to the comparator 53.
I)/A converter 52 functions to convert the digital data of the fuel injection amount control value via PI043 into an analog voltage.

Next, the operation will be explained according to flowchart 1 in FIG.

In sl of flowchart I, it is determined whether or not it is reproduction time. Although this flowchart simplifies the part of determining the playback time, the determination is made by reading VP1 and VP2, calculating (VP I - VP 2)/VP 1, and comparing this with a predetermined value. conduct.

If it is determined that it is time to regenerate, proceed to flowchart 1.
The program advances to S2 and starts playing.

Zunawara, switch once? f147.48.4! 'l Relay for claw plug +7, 3-way valve for air supply 1
4 and MA, HO:/ 7 relay I6 is activated as appropriate, and the fuel pump relay 16 is activated at the same time.
Open 7”-1・51.

When the gate 51 opens, a triangular wave from the triangular wave oscillator 5o is input to the comparator 53. On the other hand, the control value of the fuel injection amount based on the rotational speed and load at that time is 8 from PI043.
After being outputted as a digital value of HI node and converted into a ζanalog voltage by a D/A converter 52, a comparator 5
3 is input. When this analog voltage (slice level) and the triangular wave are compared by the comparator 53, a signal whose pulse width is controlled by the analog voltage is obtained, and this signal is amplified by the amplifier 54 to drive the fuel injection valve IO. .

When playback starts, VP+ and VP2 are read in s3 of the flowchart, VP1/VPp is calculated in s4, and S
In step 5, it is determined whether ■PI/■P2 is less than a predetermined value. If No, go back to s3 and repeat this.

If the determination in S5 is YES, the process proceeds to the next step 86, where the fuel injection valve 10 and the like are deactivated and regeneration is stopped.

As explained above, according to the present invention, after the burner starts operating, the trap inlet side pressure P1 and the output side pressure P2 are monitored, and when the ratio P2/P1 becomes less than a predetermined value, regeneration is completed. Since the operation of the burner is stopped based on the judgment, the completion of regeneration can be accurately detected and the operation of the burner can be appropriately controlled, which is extremely favorable in terms of fuel consumption and drivability.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram of exhaust pressure after the start of regeneration, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a block diagram showing a specific example of the structure of the control device shown in Fig. 2. , Figure 4 is the second
FIG. 5 is a block diagram showing a specific example of the configuration when a microcomputer is used as the control device in the figure, and FIG. 5 is a flowchart of the same. 1... Exhaust passage 4... Trap 5... Burner 6... Combustion cylinder 7... Backflow type Geihatsu w5
8...Mixture gas conduit 9...Glow plug 1
0...Fuel injection valve 12...Fuel pump 13
... Air pump 14 ... Three-way valve I8 ... Inlet side pressure sensor 19 ... Outlet side pressure sensor 23
...Control device 31...-Regeneration timing detection circuit 3
2... Output circuit 33... Regeneration stop circuit Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] 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 an exhaust pressure detection unit installed at the exhaust inlet and outlet of the trap. and a control device that detects the state of particulate collection from the trap inlet pressure and outlet pressure based on the signals from these pressure sensors, determines whether regeneration is necessary, and operates the burner. In the internal combustion engine, after the burner starts operating, 1-lap inlet pressure P1 and outlet pressure P2 are determined based on signals from the trap population side pressure sensor and the outlet side pressure sensor.
Control of a burner for regeneration of a trap for collecting exhaust particulates in an internal combustion engine, characterized in that a means is provided for calculating a ratio PI/P2 between the two and stopping the operation of the burner when this ratio becomes less than a predetermined value. Device.