JPH0636263Y2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an exhaust gas purification apparatus for an internal combustion engine, and more particularly to a technique for improving a filter regeneration burner.

<Prior Art> Conventional examples of this type of exhaust gas purifying apparatus for an internal combustion engine are as follows (Japanese Patent Laid-Open No. Sho 60-1314 and Japanese Utility Model Laid-Open No. Sho 6-6).
0-69313 publication).

That is, a burner is provided in the exhaust passage on the upstream side of the filter that collects exhaust particulates, and during regeneration, the burner is operated by fuel to heat and burn the exhaust particulates collected in the filter to regenerate the filter.

By the way, since light oil, which is a fuel for burners, has a higher viscosity and a higher boiling point than gasoline and the like, it has poor atomization and vaporization characteristics.
Therefore, conventionally, fuel is injected at high pressure, an evaporation cylinder is provided to cover the tip of a nozzle for injecting fuel, or a fuel collision plate is provided to promote atomization and vaporization of fuel. There is.

<Problems to be Solved by the Invention> However, since vaporization of fuel is not promoted immediately after ignition of the burner in the conventional one, unburned fuel in droplet form reaches the filter and adheres thereto. Then, after the regeneration of the filter is started, the fuel burns in the filter, which causes an increase in the regeneration temperature of the filter, and there is a problem that cracks and melting damage of the filter are easily induced.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an exhaust emission control device capable of significantly improving vaporization of combustion in a burner.

<Means for Solving the Problems> Therefore, according to the present invention, a porous ceramic heating element is provided at the fuel passage outlet at the tip of the nozzle of the burner that burns when the filter is regenerated, and the fuel flow rate is controlled in the fuel passage. I tried to insert a valve.

<Operation> In this way, the fuel is vaporized by heating the ceramic heating element at the tip of the nozzle to improve the combustion performance of the burner and prevent unburned fuel from adhering to the filter. .

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, a filter 2 for collecting exhaust particulates is installed in an exhaust passage 1 of a diesel engine. A burner 3 is provided in the exhaust passage 1 upstream of the filter 2 so as to be located in front of the filter 2.

The burner 3 is provided with an inner cylinder 4 and an outer cylinder 5 concentrically with their openings facing the filter 2. The tip of the burner nozzle 6 faces the inside of the inner cylinder 4,
Fuel oil is supplied from the fuel pump 7. Combustion air is supplied into the outer cylinder 5 by an air pump 8, and an ignition plug 9 is exposed in the inner cylinder 4.
A temperature sensor 10 is provided at the inlet of the filter 2, and the detection signal of the temperature sensor 10 is input to the control circuit 11.
The control circuit 11 controls the combustion pump 7 when the filter 2 is regenerated.
The air pump 8 and the plug 9 are operated.

As shown in FIG. 2, the burner nozzle 6 is provided with a fuel passage 12 leading to the fuel pump 8.
At the outlet of 12 is provided an electric heating element 13 made of ceramics, such as a silicon carbide foam material. The electric heating element 13 has a large number of holes for passing fuel. The electric heating element 13 is applied with a power source 15 through a switch 14 to generate heat and heat the light oil to about 400 ° C. (light oil vaporization temperature) to vaporize the light oil. A fuel flow rate control valve 16 is provided in the fuel passage 12, and the fuel flow rate control valve 16 is controlled by the control circuit 11.

Incidentally, 17 is an insulating member.

Next, the operation will be described.

When a predetermined amount of exhaust particulates are collected by the filter 2 and it is judged that it is a regeneration time, the electric heating element 13 is energized for a predetermined time to generate heat until a predetermined temperature (for example, 400 ° C.) is reached. After that, the fuel flow rate control valve 16 is operated to transfer the light oil to the electric heating element.
It is passed through 13 and jetted from the tip of the burner nozzle 6.
At this time, the light oil is vaporized by the electric heating element 13 and injected from the tip of the burner nozzle 6.

Then, the injected light oil is ignited by the plug 9 to start combustion, and the exhaust particulates collected by the filter 2 are heated and burned to regenerate the filter 2.

As described above, the electric heating element at the tip of the burner nozzle 6
Since the light oil is vaporized at 13, the fuel can be reliably ignited by the plug 9, the system reliability can be improved, and the unburned fuel can be prevented from adhering to the filter 2. It is possible to prevent cracks and melting of the filter 2 caused by the fuel burn. Further, since the ceramic heating element 13 has a large number of holes formed therein, there are very few injection defects due to clogging of the fuel in the fuel compared with the conventional fine hole nozzle, so that the reliability and durability of the burner are improved. Is excellent.

<Effects of the Invention> As described above, according to the present invention, the porous ceramic heating element is provided at the exit of the fuel passage at the tip of the nozzle, and the fuel flow control valve is provided in the fuel passage. Since the vaporization of No. 1 is greatly promoted, the reliability and durability of the burner can be greatly improved, and cracking and melting damage of the filter can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of the same. 1 ... Exhaust passage, 2 ... Filter, 3 ... Burner, 6 ... Burner nozzle, 12 ... Fuel passage, 13 ... Electric heating element, 16 ... Fuel flow control valve

Claims (1)

[Scope of utility model registration request] 1. An exhaust gas purification apparatus for an internal combustion engine, comprising: a filter installed in an exhaust passage for collecting exhaust particulates; and a burner provided in an exhaust passage upstream of the filter for performing a combustion operation when the filter is regenerated, An exhaust gas purifying apparatus for an internal combustion engine, wherein a porous ceramic heating element is provided at a fuel passage outlet at a tip of the burner nozzle, and a fuel flow rate control valve is provided in the fuel passage.