JPH0114726Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present application relates to an exhaust particulate separator used in the exhaust system of an internal combustion engine, particularly a diesel engine.

The particulates in the exhaust mainly consist of submicron-order carbon particles. Therefore, in order to separate and remove this, a filter having a fine heat-resistant material is used. However, such a filter causes premature clogging and cannot withstand long-term use. Therefore, in addition to such a filter, an exhaust particulate separation device has been proposed which is further provided with a filter regeneration means. The regeneration means is a heating device that heats a filter that is clogged with carbon particles and restores the filter function of burning out the carbon particles. Heating in that case is done by a fuel burner. Fuel burners are superior to heating devices such as electric heaters in that they can reliably obtain high temperatures, and are in practical use.

As shown in FIG. 1, a conventional exhaust particulate separator is comprised of a filter 2 provided downstream of an exhaust pipe 1 and a fuel burner 4 provided in front of an inlet surface 3 of the filter. Furthermore, an auxiliary air supply pipe 5 is provided near the fuel burner 4 . This device uses a fuel burner 4 that injects and ignites fuel when the filter 2 is clogged with carbon particles.
is activated to heat the filter 2 and burn out the captured carbon particles.

By the way, in such an apparatus, in order to improve filter regeneration, the fuel burner 4 needs to satisfy the following requirements. First, the heating must be uniform to prevent the filter 2, which is made of a heat-resistant material, from being unevenly heated and damaged due to thermal distortion. Second, the fuel burner 4 must be able to burn stably even when the operating state of the engine (engine speed, etc.) changes. (References, SAE TECHNICAL PAPER SERIES
No. 810118).

In view of the above, the present application provides a heat-resistant filter in the exhaust pipe, a guide tube whose tip is closed around the nozzle of the fuel injector in front of the filter, and a small hole or a hole in the lower bottom wall of the guide tube. By providing a restriction hole such as a slit, installing a fuel burner with a burner tube around the guide tube, and installing an ignition device inside the burner tube, the fuel from the fuel injector became coarse. This prevents the liquid from burning in the form of droplets, resulting in stable and uniform combustion.

To describe an embodiment, FIG. 2 shows an exhaust particulate separator 10 according to the present invention, in which a fuel burner 12 and a filter 13 are sequentially arranged in an exhaust pipe line 11. The filter 13 is made of ceramic, which is a heat-resistant material, and has a so-called honeycomb shape or a three-dimensional mesh shape. As another example, it may be made of metal mesh. fuel burner 12
has a guide cylinder 16 provided around the nozzle 15 of the fuel injector 14 whose tip is closed, and a burner cylinder 17 connected to the outside of the guide cylinder 16 with one end closed and the other end open, The other open end of the burner cylinder 17 is open to the exhaust pipe 11 and is located facing the filter 13.

A number of small holes 18 are bored in the bottom wall of the guide tube 16, and the inside of the guide tube 16 communicates with the burner tube 17 through the small holes 18. The small hole 18 of the guide tube 16 is set to have a hole diameter of, for example, about 2 mm so that liquid fuel does not easily flow down.

FIG. 3 shows another embodiment of the guide tube 16,
A slit 18a extending in the longitudinal direction is provided in the lower wall. Similarly to the above, the width of the slit 18a is set to such an extent that liquid fuel cannot easily flow down, for example, about 2 mm. A swirling flow forming means, for example, an auxiliary air pipe 20 provided tangentially to the side wall near the closed end is attached to the burner cylinder 17. Another swirling flow forming means is one in which swirling vanes are provided at the closed end of the burner cylinder 17. Burner tube 17
An ignition device 19, for example a glow or a spark plug, is provided therein. The fuel injector 14 may be one for high pressure or one for low pressure.

The exhaust particulate separator 10 is connected to an exhaust manifold of a diesel engine and put into use.

The exhaust gas containing carbon particles passes through the exhaust pipe line 11 to reach the inlet surface 13a of the filter 13, further flows through the filter 13, and is discharged to the atmosphere. Carbon particles are captured while flowing through the filter 13. When the filter 13 reaches a predetermined clogging state, the ignition device 19 is ignited and the fuel injector 14 is started by means (not shown) that senses and operates the differential pressure across the filter 13, for example. At the same time, auxiliary air is introduced into the burner cylinder 17 from the auxiliary air pipe 20. fuel injector 1
The fuel injected from the nozzle 15 of No. 4 stays in the guide cylinder 16 in the form of mist or droplets, and then condenses within the guide cylinder 16. At the same time, the ignition device 19 is ignited, causing auxiliary air to swirl from the auxiliary air pipe 20 and flow into the burner cylinder 17. A small portion of the fuel in the guide tube 16 becomes large droplets, which are finally scattered by gravity into the burner tube 17 through the small holes 18, and are ignited and burned by the ignition device 19. When combustion begins in the burner tube 17, the guide tube 16 is heated, and the fuel present in the small holes 18 or slits 18a of the guide tube 16 is heated, evaporated, and diffused into the burner tube 17, causing continuous combustion. Let it continue.
As a result, the fuel is reliably delivered to the burner cylinder in a vaporized state through the small hole 18 or slit 18a of the guide cylinder 16.
7, resulting in homogeneous combustion. The combustion flame at this time becomes relatively homogeneous due to the guide tube 16 and the swirling flow, mixes with the exhaust gas, and increases the exhaust temperature, thereby heating the filter 13 uniformly. When the temperature of the filter 13 reaches a predetermined temperature or higher, the carbon particles captured by the filter 13
The filter 13 is regenerated and its function is restored. When the differential pressure created by the filter 13 decreases, both the fuel supply and the scavenging air supply to the fuel burner 12 are stopped. Incidentally, the auxiliary air can also be made to flow continuously during operation, regardless of whether or not the filter 13 is clogged.

As described above, the present invention provides a filter in the exhaust pipe line and a fuel burner consisting of a burner cylinder equipped with a fuel injector, a guide cylinder, an ignition device, and a swirl flow forming means in front of the filter. In a separator, a restriction hole such as a small hole or slit is provided in the lower bottom wall of the guide cylinder, so the fuel injected from the fuel injector becomes small droplets, resulting in an uneven or unstable combustion state. It is possible to prevent this from occurring, uniformize the heating of the filter, and effectively regenerate the filter function.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional device, and FIG. 2 is a sectional view of the device of the present invention. Furthermore, FIG. 3 shows another embodiment of the guide tube. 12...Fuel burner, 13...Filter, 14
...Fuel injector, 16...Guide tube, 18...
...small hole, 18a...slit.

Claims (1)

[Scope of utility model registration request] A heat-resistant filter is provided in the exhaust pipe line, and a guide tube whose tip is closed is provided around the nozzle of the fuel injector in front of the filter, and a restriction hole is bored in the lower bottom wall of the guide tube. An exhaust particulate separator comprising a fuel burner having a burner cylinder on its outer periphery that is closed at one end and open at the other end and has an auxiliary air swirling flow forming means on the wall surface, and an ignition device disposed inside the burner cylinder.