JPS61244813A - Processor for fine particle in exhaust from internal-combustion engine - Google Patents

Abstract

PURPOSE:To substantially reduce a number of operating times of a burner, by actuating an air supplier and supplying air to a trap so as to enable an exhaust gas fine particle to perform combustion only by exhaust heat when the trap is decided to reach no- regeneration timing furthter with the temperature of exhaust in a predetermined value or more. CONSTITUTION:The captioned device, interposed in an exhaust passage B of an engine A, has a trap C, catching a fine particle in exhaust to be collected, and a trap regenerating burner D heating the exhaust fine particle, caught by said trap C, to be destroyed by fire. And when a regeneration decision means F detects the trap to reach its regeneration timing on the basis of an output signal from a collected amount detecting means E detecting a collected amount of the exhaust fine particle in the trap C, the means F actuates the burner D to be controlled through a burner control unit G. Here when the regeneration decision means F decides the trap to reach no regeneration timing further when the temperature of exhaust detected by an exhaust temperature detecting means H is in a predetermined value or more, the device, controlling an air supply unit I by an air control unit J and supplying air to the trap C, enables the exhaust gas fine particle to perform combustion.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an exhaust particulate treatment device for an internal combustion engine.

(Prior art) In an internal combustion engine such as a diesel engine installed in a vehicle, which is equipped with a collection device (hereinafter referred to as a trap) in the exhaust passage for collecting fine particles such as carbon in the exhaust, the exhaust gas collected in the trap is If the number of particulates increases, the exhaust pressure will rise excessively and the engine and emission performance will deteriorate. Therefore, the exhaust particulates collected in the trap are combusted at a predetermined time to regenerate the trap. As shown in Fig.
(See Publication No. 115809).

That is, a trap 2 for collecting exhaust particulates is installed in the middle of an exhaust passage 1 of an internal combustion engine mounted on a vehicle. The amount of exhaust particulates collected in trap 2 increases and trap 2
The state in which the degree of clogging increases is detected by the differential pressure detector 3 as a difference between the static pressures before and after the trap 2. When the differential pressure reaches a predetermined value, the solenoid valve 6 installed in the fuel supply passage 5 is opened by a signal from the control circuit 4, and the fuel is transferred from the fuel pump 7 to the jet nozzle 9 of the burner 8. Supply under pressure. Further, in response to a signal from the control circuit 4, the IIT magnetic valve 11 installed in the air supply passage 10 is opened to supply air under pressure to the jet nozzle 9 from the air pump 12.

Then, a mixture of fuel and air is ejected from the jet nozzle 9, and the preheated glow plug 13 ignites and burns the mixture. This heated the mixed gas to heat and incinerate the exhaust particles, thereby regenerating the trap. Note that 3a and 3b are pressure terminals for introducing the exhaust pressure before and after the trap 2 into the differential pressure detector 3, and 14 is a fuel tank.

<Problems to be solved by the invention> However, in such a conventional exhaust particulate treatment device, the number of burner operations is large, fuel consumption in the burner increases, and the durability of the burner decreases due to thermal deterioration. I...There was a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust particulate treatment device for an internal combustion engine that can incinerate exhaust particulates collected in a trap without operating the burner more than necessary. do.

Means for Solving the Problems> Therefore, as shown in FIG. A trap regeneration burner D that heats and incinerates the collected exhaust particulates, a trapped amount detection means E that detects the amount of collected exhaust particulates in the trap C, and a detection signal that determines whether or not regeneration of the trap C is necessary. An exhaust particulate treatment device for an internal combustion engine, comprising a regeneration determination means F for making a determination, and a burner control device G for operating the burner D when determining the need for regeneration, an exhaust temperature detection means H for detecting exhaust temperature, and the trap C. an air supply device I that supplies air to the
The apparatus further includes an air control device G that operates the air supply device (2) to supply air to the trap C when a determination is made as to whether or not regeneration is required and the exhaust gas temperature exceeds a predetermined value.

<Function> Then, by supplying air during the non-regeneration period and when the exhaust gas temperature is above a predetermined value, the oxygen concentration in the exhaust gas is increased and exhaust particulates are combusted only by the exhaust heat. This greatly reduces the number of times the burner operates, thereby reducing burner fuel consumption and improving burner durability.

(Example) An example of the present invention will be described below based on FIG. 2.

In FIG. 2, a honeycomb-shaped catalyst trap 23 is housed in a trap case 22 installed in an exhaust passage 21 of the engine via a buffer material 22a, and this catalyst trap 23 collects fine particles in the exhaust gas. Collect. A burner 24 is provided in the exhaust passage 21 upstream of the catalyst trap 23, and when a predetermined amount of exhaust particles are collected in the catalyst trap 23, the burner 24 is ignited by a signal from a control device 25, which will be described later. , heating and incinerating exhaust particulates.

The burner 24 includes a combustion tube 26 in which a large number of exhaust gas introduction holes 26a are formed in the peripheral wall, and a flame injection hole 27 located inside the combustion tube 26.
a backflow type evaporator 27 having a diameter of
7, and a glow plug 29 for ignition facing near the flame outlet 27a. A fuel supply pipe 31 extending from an electromagnetic fuel injection valve 30 is connected to the mixture conduit 28, and fuel (engine) is supplied to the electromagnetic fuel injection valve 30 from a fuel tank 32 via a fuel pump 33. The same fuel (for example, light oil) is used. Further, an air supply pipe 36 is connected to the middle of the fuel supply pipe 31, which communicates with the discharge port 34b of the air pump 34 via a diaphragm type three-way valve 35. When the atmosphere is introduced into the pressure chamber of the diaphragm type three-way valve 35, the first boat 35a connected to the discharge port 34b is opened.
communicates with the second port 35b which is open to the atmosphere, and when a predetermined negative pressure is introduced, the first boat 35a communicates with the third port 35c connected to the air supply pipe 36, and the air is discharged from the air pump 34. It is configured to supply air to the burner 24.

The second boat 35b and the suction port 34a of the air pump 34 are both open to the atmosphere via an air cleaner (not shown). On the other hand, switching of the pressure introduced into the diaphragm type three-way valve 35 is performed by an electromagnetic type three-way valve 37. This electromagnetic three-way valve 37 is a first boat 37
a is connected to the pressure chamber of the diaphragm three-way valve 35, the second boat 37b is connected to a negative pressure source (for example, a vacuum pump) not shown, and the third port 37C is open to the atmosphere, In the de-energized state, the first port 1-37a
and the third port 37C communicate with each other, and in the energized state, the first port 37a and the second port 37b communicate with each other.

Therefore, the operation of the burner 24 is controlled by the electromagnetic three-way valve 37,
Fuel pump 33. Fuel injection valve 30 and glow plug 29
controlled by. The electromagnetic three-way valve 37, the fuel pump 33, and the fuel injection valve 30 are connected to a control device 2, which will be described later.
Grounding device based on power transistor 5! 38, each of them is controlled to be energized, and specifically, when grounded, each is activated by energization from the battery 40 via the key switch 39. Further, the glow plug 29 is connected to the battery 40 via a normally open relay 41, and the relay 41 is the same (which is closed when grounding is performed by the grounding device 38).

The exhaust passage 21 on the inlet side and the outlet side of the catalyst trap 23 is provided with an inlet side pressure outlet 42 and an outlet side pressure outlet 43, respectively. An inlet side pressure sensor 44 and an outlet side pressure sensor 45 are attached as means.

The pressure sensors 44 and 45 are, for example, semiconductor pressure sensors in which a gauge resistor is provided on the surface of a silicon diaphragm so as to sense the pressure by a piezoresistance effect, and the trap inlet pressure P is detected.

and outlet pressure P2 is detected as gauge pressure.

Output voltages vp, , vp2 of these pressure sensors 44, 45
is input to the control device 25.

On the inlet side of the trap 23, an exhaust temperature sensor 46 as exhaust temperature detection means consisting of a thermocouple or the like is installed.
The output voltage VT corresponding to the temperature T is similarly input to the control device 25.

Also, a rotation speed sensor 4 for detecting the engine rotation speed
7 and the control lever 48a of the fuel injection pump 48
A load sensor 49 such as a potentiometer that rotates in conjunction with the
L is input to the control device 25. Rotational speed sensor 4
Reference numeral 7 is constituted by, for example, a crank angle sensor that generates a pulse at every fixed rotation angle of the crankshaft.

The control '4' FA device 25 connects the CPU 50 and this CPU 5.
00 memory (ROM) 51 in which the control program and predetermined data are written, the output voltages VP+ and VPz of the pressure sensors 44 and 45, and the output voltage VT of the exhaust temperature sensor 46.
.

A multiplexer 53 that selects one of the output voltages VR from the rotational speed sensor 47 via the F/V converter 52 and the output voltage VL from the load sensor 49, and converts the selected analog data into digital data. the A/D converter 54, the aforementioned grounding device 38, and the multiplexer 53. A/D converter 54 and grounding device 3
PIO (
Peripheral l10) 55 and batch 1/0 voltage VB
and a constant voltage device 56 that changes the voltage to a constant voltage Vcc. Note that the CPtJ issues a channel instruction to the multiplexer 53 via the PIO 55, and
After receiving the EOC signal indicating the end of conversion from the converter 54, the digitally converted data is input.

Further, the grounding bag W38 has four systems of grounding control circuits 39a to 39d mainly composed of power transistors, each having a fuel pump 33. Fuel injection valve 30. Electromagnetic three-way valve for air control37. The grounding wire of the relay coil 41a of the relay 41 for the glow plug 29 is connected, and when a signal is sent from the CPtJ50 via the P4O10, the grounding is performed and each device is operated. The CPU 50 operates according to a program based on the flowchart shown in FIG. Here, the air pump 34 and the three-way valve 35 constitute an air supply device, and the control device 25 serves as a regeneration determining means, a burner control device, and an air control device.

Next, the operation will be explained based on the flowchart shown in FIG. At Sl, a rotational speed sensor 47. via an F/V converter 52. Load sensor 49. Exhaust temperature sensor 46
．． Output voltage VR of pressure sensor 44.45.

VL5. VT, vp+, vpz are stored in the storage section of the CPU 50 (
RAM). Then, in S2, it is determined whether or not the engine rotation speed is 500 rpm or higher, for example, and if the result is No, the process proceeds to S9 to stop the burner operation (
Solenoid three-way valve 37. Fuel pump 33. Grounding of the fuel injection valve 30 and the relay 41 of the glow plug 29 is stopped)
to maintain the deactivated state.

If YES in S2, it is determined in S3 whether or not playback is currently in progress (it is determined whether or not a symbol indicating that playback is in progress is stored in the storage section (RAM) of the CPU 50). If YES, proceed to S7, but if NO, proceed to S4 VR and VL
The limit differential pressure at the trap inlet and outlet (differential pressure at the particle collection limit) ΔV is set according to the rotation speed and load.
P, . . . are searched from the memory 51 and obtained.

Then, proceeding to S5, it is determined whether the differential pressure ΔVP (VP+VPz) has reached the limit differential pressure Δvp,,x, and N
If O, it is not the regeneration time, proceed to S9 and select YES.
In this case, a symbol indicating that regeneration is in progress is stored in the storage section (RAM) of the CPU 50 in S6, and the process proceeds to S7 to control the operation of the burner 24. That is, the relay 41 of the glow plug 29 is closed to heat the glow plug 29 until the temperature reaches the temperature required for ignition, and then the electromagnetic three-way valve 37. fuel pump 33
The fuel injection valve 30 is driven with a predetermined pulse signal to obtain the temperature necessary for regenerating the catalyst trap 23, and air and fuel are supplied to the burner 24 for combustion. After ignition, the glow plug The grounding of the relay 41 of the glow plug 29 is stopped, and the heating of the glow plug 29 is stopped. Then, proceed to S8, start the operation of the burner 24, and then proceed to the trap 2 with catalyst.
It is determined whether or not a predetermined time (for example, 3 minutes) required to complete the regeneration of No. 3 has been reached, and if No, the process returns to Sl and continues combustion in the burner 24 until the regeneration is completed. If it is YIES in S8, that is, if the regeneration of the catalyst trap 23 is completed, the operation of the burner 24 is stopped in S9, and the operation is continued in S1.
At step 2, the symbol indicating that the reproduction is in progress stored in the storage section (RAM) of the CPU 50 is deleted, and the process returns to -81.

In this way, when it is determined that it is time to regenerate, the burner 2
The combustion operation in step 4 increases the temperature of the exhaust gas flowing into the catalyst trap 23, incinerates the exhaust particulates collected in the catalyst trap 23, and regenerates the catalyst trap 23.

If No in S5, that is, if it is determined that the reproduction is not possible, the SI
The process proceeds to O, and it is determined based on the output voltage ■T of the exhaust temperature sensor 46 whether the exhaust gas temperature is at least a temperature suitable for self-regeneration of the catalyst trap 23 (temperature at which the catalyst is activated, for example, 400° C.). , in the case of YES, the Sll only energizes the electromagnetic three-way valve 37, supplies negative pressure from a vacuum pump (not shown) to the pressure chamber of the diaphragm three-way valve 35, and supplies air from the air pump 34 to the burner 24. . At this time, glow plug 29. Fuel injection valve 30 and fuel pump 3
3 is stopped, and the combustion operation of the burner 24 is stopped.

Therefore, since the air supplied to the burner 24 is introduced into the exhaust passage 21, the oxygen concentration in the exhaust becomes high. At this time, since the exhaust gas temperature is higher than the catalyst activation temperature T1,
The catalyst is activated and the trap with catalyst 23 is activated only by exhaust heat.
It is possible to self-combust the collected exhaust particulates. In particular, in the low to medium speed and high load operating range shown in Figure 4 (AM range in Figure 4), the oxygen concentration in the exhaust gas discharged from the engine is low (see Figure 5), and the exhaust temperature is the activation temperature of the catalyst. Even with the above conditions, it was difficult to burn the exhaust particulates only by the exhaust heat, but according to this embodiment, the oxygen concentration in the exhaust gas increases, so it becomes possible to self-combust the exhaust particulates only by the exhaust heat. In addition, in the high-speed, high-load operation region (region B in Figure 4), the oxygen concentration in the exhaust gas discharged from the engine is relatively high, and self-combustion can occur only with exhaust heat without supplying air. As shown in FIG. 5, the amount of exhaust particulates increases as the load increases, so by supplying air, the self-combustion efficiency of the exhaust particulates can be increased.

As explained above, since air is supplied to the catalyst trap 23 when no regeneration is performed and the exhaust temperature is higher than the activation temperature of the catalyst, the exhaust heat causes the exhaust particulates to self-isolate over a wider operating range than before. Combustion can be achieved. For this reason, the amount of exhaust particulates from the catalyst trap 23 is reduced to the burner 24.
The time it takes to reach the limit value required for operation becomes significantly longer, and the number of times the burner 24 is activated is significantly reduced. For this reason,
The fuel consumption of the burner 24 can be greatly reduced, and the durability of the burner 24 can be improved.

In this example, a trap with a catalyst is described, but in a trap without a catalyst, the air supply control area is such that air is supplied when the exhaust temperature is T2 (for example, 600°C) or higher, as shown in Fig. 4. good. Further, although air is supplied to the catalyst trap 23 via the burner 24, air may be directly supplied to the catalyst trap 23.

<Effects of the Invention> As explained above, the present invention supplies air to the trap when no regeneration is occurring and the exhaust temperature is above a predetermined value, so that exhaust particulates can be exhausted over a wider operating range than before. Since self-combustion can be carried out using only heat, the number of burner operations is greatly reduced, thereby reducing the burner's fuel consumption and improving the durability of the burner.

[Brief explanation of drawings]

Fig. 1 is a claim correspondence diagram of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the present invention, Fig. 3 is a flowchart of the same as above,
FIG. 4 and FIG. 5 are diagrams for explaining the same operation as above, and FIG. 6 is a configuration diagram showing a conventional example of an exhaust particulate processing device. 23... Trap with catalyst 24... Burner 2
5...Control device 30...Fuel injection valve 34.
...Air pump 35...Diaphragm type three-way valve 4
4.45 Pressure sensor 46 Exhaust temperature sensor Patent applicant Nissan Motor Co., Ltd. Agent Patent attorney Tomio Sasashima Figure 1 Figure 4 Engine direction a Speed - Large Figure 5 Engine rotation degrees - eleven dogs

Claims (1)

[Claims] A trap installed in an exhaust passage of an engine to collect particulates in exhaust gas, a trap regeneration burner to heat and incinerate the exhaust particulates collected in the trap, and a trap to detect the amount of exhaust particulates collected by the trap. An exhaust particulate processing device for an internal combustion engine, comprising: a collection detection means; a regeneration determination means for determining whether trap regeneration is necessary based on the detection signal; and a burner control device for operating the burner when regeneration is determined. an exhaust temperature detection means for detecting exhaust temperature; an air supply device for supplying air to the trap; and an air supply device for operating the air supply device to supply air to the trap when a regeneration failure determination is made and the exhaust temperature is equal to or higher than a predetermined value. An exhaust particulate processing device for an internal combustion engine, characterized in that it is equipped with an air control device that supplies