JPH0461165B2 - - Google Patents

Description

Detailed Description of the Invention <Technical Field> The present invention relates to an exhaust particulate treatment device for an internal combustion engine.

<Prior art> Exhaust from internal combustion engines, such as diesel engines, contains many exhaust particulates whose main component is carbon, so these particulates are collected by a trap installed in the middle of the exhaust passage and prevented from dispersing to the outside. I'm trying to prevent it.

As a conventional example of such an exhaust particulate treatment device, the first
There is one shown in the figure (see Japanese Unexamined Patent Publication No. 115809/1983).

That is, an exhaust pipe 4 is connected to the exit of the turn 3 of the supercharger 2 connected to the exhaust manifold 1 of the internal combustion engine.
A trap 5 for collecting fine particles is connected through the
This trap 5 collects fine particles contained in the exhaust gas.

When a predetermined amount of fine particles are collected in the trap 5, a burner device 6 provided upstream of the trap 5 is activated to heat and burn the fine particles stored in the trap 5.
I am trying to regenerate Trap 5.

The burner device 6 also includes fuel supplied from a fuel injection valve 7 and an air pump 8 driven by the engine.
A mixture with air supplied from the air mixture is introduced via the mixture supply passage 9.

However, in such a conventional exhaust particulate treatment device, air is supplied from the air pump 8, so when the trap 5 is regenerated in all operating ranges of the engine, the air pump 8 that supplies air to the burner device 6 has a large capacity, and the trap There was a problem that the playback device of No. 5 was large.

In addition, a large capacity air pump 8 is connected to the burner device 6.
Because it is driven by the engine even when it is not operating,
In this case, there is a problem in that the air pump 8 places an unnecessary load on the engine, leading to a decrease in engine output or deterioration in fuel efficiency.

<Object of the Invention> In view of these conventional problems, an object of the present invention is to reduce the size of a trap regeneration device, and to prevent a decrease in engine output and deterioration of fuel efficiency.

<Structure of the Invention> Therefore, in the present invention, a first combustion air supply passage that supplies air discharged from a compressor of a supercharger to the mixture supply passage, and a first combustion air supply passage that supplies air discharged from a compressor of a supercharger to the mixture supply passage; A second combustion air supply passage that supplies exhaust gas from the exhaust passage, and a switching device that selectively switches between these two passages are provided.

<Example> The present invention will be described below based on an example shown in FIGS. 2 and 3.

A compressor 14 and a turbine 15 of a supercharger 13 are respectively interposed in a gathering part of an intake manifold 11 and an exhaust manifold 12 of the engine, thereby forming an internal combustion engine with a supercharger. The inlet of the compressor 14 is connected to the clean side of an air cleaner 17 via an intake duct 16, and the exhaust outlet of the turbine 15 is connected to a conventional trap 19 via an exhaust passage 18. A burner device 20 is installed upstream of this trap 19. Inside the burner device 20 is a mixture supply passage 2 that supplies a combustion mixture to the burner device 20.
The open end of No. 1 is facing forward. Mixture supply passage 2
A fuel injection valve 22 is provided at the upstream end of the fuel injection valve 1 .

The air-fuel mixture supply passage 21 near the fuel injection valve 22 is branched, and the upstream end of this branch passage 23 is connected to the downstream ends of first and second combustion air supply passages 24 and 25. The upstream end of the first combustion air supply passage 24 is connected to a supercharging duct 26 extending from the outlet of the compressor 14 of the supercharger 13 to the gathering part of the intake manifold 11, and the upstream end of the first combustion air supply passage 24 is The upstream end is the exhaust manifold 12
It is connected to an exhaust passage 18 that extends from the inlet of the turbine 15 to the inlet of the turbine 15. Further, flow control valves 26 and 27 are interposed in the first and second combustion air supply passages 25. These flow control valves 26 and 27 are provided with negative pressure introduction pipes 2 for introducing negative pressure air into the flow control valves 26 and 27.
The downstream ends of the negative pressure introduction pipes 28a and 28b are connected to each other, and the upstream ends of the negative pressure introduction pipes 28a and 28b are connected to the respective outlets of the electromagnetic switching valve 29, respectively. The electromagnetic switching valve 29 receives a signal from a control device (not shown), and supplies negative pressure air to one of the flow control valves 27 in a low engine load operating region where the residual oxygen in the exhaust is, for example, 15% or more. Exhaust air is introduced into the mixture supply passage 21 via the second combustion air supply passage 25, and in other operating regions, negative pressure air is supplied to the other flow control valve 26 and discharged from the compressor 14. The combustion air is introduced into the air-fuel mixture supply passage 21 via the first combustion air supply passage 24. Further, the control device outputs an actuation signal to the electromagnetic switching valve 29 based on the rotational speed and load of the engine and a preset operating state of the engine.

Note that 30 is a flow rate control valve 2 for negative pressure air introduced from a negative pressure supply source (not shown) through a negative pressure passage 31.
32 is a glow plug for ignition of the burner device 20; Here, the flow rate control valves 26, 27, the electromagnetic switching valve 29, and the control device constitute a switching device.

Next, the operation of such an exhaust particulate processing device will be explained.

The exhaust gas that has driven the turbine 15 of the supercharger 13 flows through the exhaust passage 18 and is introduced into the trap 19.
The trap 19 collects exhaust particulates such as carbon contained in the exhaust gas, and the exhaust gas is released into the atmosphere in a clean state.

When it is determined that a predetermined amount or more of exhaust particles are collected in the trap 19, the trap 19 is detected by a pressure sensor (not shown), for example.
The burner device 20 is activated when the differential pressure across the trap 19 relative to the upstream exhaust pressure reaches a predetermined value or higher, and the exhaust temperature detected by a temperature sensor (not shown) at the inlet of the trap 19 is below a predetermined value. The exhaust particles collected in the trap 19 are heated and burned to regenerate the trap 19.

When the trap 19 is regenerated, the rotational speed and load of the engine are detected, and the control device outputs an operating signal to the electromagnetic switching valve 29 based on these detected values and a preset operating state of the engine. That is, in the region C (region below the broken line) in FIG. 3 where the residual oxygen concentration in the exhaust gas is, for example, 15% or more,
The electromagnetic switching valve 29 supplies negative pressure to one of the flow rate control valves 27 to control the flow rate control valve 27, and the exhaust gas containing a large amount of residual oxygen is mixed through the second combustion air supply passage 25 and the branch pipe 23. The air is supplied to the air supply passage 21. Then, the mixture of fuel and exhaust gas injected from the fuel injection valve 22 is supplied to the burner device 20 and ignited and burned by the ignition glow plug 32.

In area A (high load operation area) in Figure 3,
The air pressurized by the compressor 14 of the supercharger 13 is supplied to the mixture supply passage 21 via the first combustion air supply passage 24 and the branch pipe 23 by controlling the flow rate control valve 26 .

Moreover, in the area B of FIG. 3, the burner device 2
Air can be supplied by appropriately delaying the fuel injection timing of the engine while the engine is operating. That is, when the fuel injection timing is delayed, the exhaust temperature rises, the boost pressure of the compressor 14 increases, and the pressurized air from the compressor 14 flows through the first combustion air supply passage 24 and the branch pipe 23. It can be supplied to the mixture supply passage 21. At this time, it is preferable to perform the control method for the B area preferentially in a portion where the B area and the C area overlap (the hatched portion in FIG. 3).

As described above, exhaust gas or air with a high oxygen concentration is supplied to the burner device 20 in almost the entire operating range of the engine to heat and burn the particulates collected in the trap 19. This eliminates the need for an air pump, making it possible to downsize the trap regeneration device. Furthermore, since the air pump is not required, it is possible to prevent a decrease in the output of the engine that is the driving source for the air pump and to prevent deterioration in fuel efficiency.

Note that the exhaust volume and air volume supplied to the burner device 20 can be optimally controlled by controlling the negative pressure controller 30 based on a duty ratio stored in advance in a control device (not shown).

<Effects of the Invention> As explained above, according to the present invention, the air discharged from the compressor of the supercharger and the exhaust air from the exhaust passage are appropriately selected and supplied to the burner device, thereby eliminating the need for an air pump. The trap playback device can be made smaller. Further, since an air pump is not required, a decrease in the output of the engine that is the driving source for the air pump and a deterioration in fuel efficiency can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional example of an exhaust particulate processing device, and FIG. 2 is a schematic diagram showing an embodiment of the present invention.
FIG. 3 is a characteristic diagram showing the operating range of the burner device described above. 12...Exhaust manifold, 13...Supercharger, 14
...Compressor, 19...Trap, 20...Burner device, 21...Mixture supply passage, 24...First combustion air supply passage, 25...Second combustion air supply passage, 26, 27...Flow rate control valve, 29 ...Solenoid switching valve.

Claims (1)

[Claims] 1. A trap that is installed in an exhaust passage and collects particulates in the exhaust gas, and a burner device that heats and burns the particulates in the exhaust gas collected by the trap,
In a supercharged internal combustion engine in which a combustion mixture is supplied to the burner device via a mixture supply passage, a turbocharger includes a turbocharger for supplying air discharged from a compressor of the supercharger to the mixture supply passage. a second combustion air supply passage that supplies exhaust gas from an exhaust passage upstream of the burner device to the mixture supply passage; and a switching device that selectively switches between these two passages; An exhaust particulate treatment device for an internal combustion engine, characterized in that it is provided with: