JPS62298615A - Diesel exhaust gas cleaning device - Google Patents

Abstract

PURPOSE:To securely carry out the regeneration of a trap by covering the exhaust gas flow-in side end of a ceramic trap for collecting carbon particulates in exhaust gas, with a wire gauze. CONSTITUTION:A ceramic trap 1 consists of a honeycomb structure 4 consisting of a number of rectangular cells 3 partitioned by highly porous ceramic walls 2, and plugs 5 for closing one end part of a cell and the other end part of an adjacent cell alternately. And, this trap 1 is housed in a can case 9 provided in an exhaust gas passage via a cushioning material 8 of an alumina-silica group fiber mat, to form an exhaust gas cleaning device. A wire gauze 13 of approx 30 mesh nichrome wire is provided in front of the exhaust gas flow-in side end part of the trap 1 leaving a space of approx. 1mm, covering the whole surface of the trap 1. Electrodes 14 are installed on both ends of the wire gauze 13, and can be electrified from a storage battery.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention is directed to carbon-based particulates (
This invention relates to an exhaust gas purification device that removes soot.

2. Description of the Related Art A conventional diesel exhaust gas purification device is one in which one end of a cell of a ceramic honeycomb structure and the other end of an adjacent cell are closed with a plug, as shown in Japanese Patent Laid-Open No. 129020/1983, for example. Some use structural traps. This trap has features such as a large filtration area, low pressure loss, and excellent collection efficiency.

Problems to be Solved by the Invention However, in a diesel exhaust gas purification device using this trap, so-called regeneration is performed, in which the particulates accumulated in the trap are incinerated after a certain collection period has elapsed. This involves igniting the particles using a burner or electric heater. At this time, the spark ignited at the end face of the exhaust gas inlet side of the trap easily propagates inside the cell in the trap axis direction (exhaust gas flow direction). There was a problem in that the regeneration did not spread in the direction perpendicular to this, resulting in incomplete regeneration.

This means that in the direction of the trap axis, the flame is swept away by the exhaust gas flow, but in the plane perpendicular to this, each cell is independent.
In addition, the plug makes the filter surface ineffective near the end face, which is the flame propagation path, and there is less accumulation of particulates.

Therefore, during beam generation according to the present invention, by making it easier for the flame to spread in a plane perpendicular to the trap axis direction,
This is an attempt to complete regeneration.

Means for solving the problems and technical means of the present invention for solving the above problems are as follows:
A lattice-shaped wire mesh is provided to cover the end face of the exhaust gas inflow side of the trap described above, and as a more effective method, the wire mesh is made of an electric heater material such as nichrome wire, and an electrical terminal is attached to it so that it can be connected to a power source. This is what I did.

action The effect of this technical means is as follows.

That is, during normal exhaust gas purification operation, fine particles contained in the exhaust gas are deposited not only in the trap but also in layers on the lattice-like wire mesh. Next, during regeneration, the layered deposited particles are ignited by an electric heater, and the flame spreads over the entire surface through the wire mesh. The ignited particles are blown away by the exhaust gas flow, turn into sparks, enter the cells of the trap, and ignite the particles deposited inside the cells.

As a result, regeneration is not limited to partial combustion, as was the case in the past, but instead extends to the entire trap. In addition, an electric heater is used to ignite the particles.
By using wire mesh itself, the flame can spread more quickly.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In the figure, 1 is a ceramic trap that collects carbon-based particulates in diesel exhaust gas. This trap 1 is composed of a honeycomb structure 4 consisting of a large number of rectangular cells 3 separated by ceramic walls 2 with high porosity, and a plug 6 that closes one end of each cell 3 and the other end of an adjacent cell 3. ing. Among the cells 3 with one end closed, the cell 3 having an end open to the exhaust gas inflow side is an inflow channel 6, and the outflow side is an outflow channel 7.

Trap 1 is a cushioning material 8 made of alumina-silica fiber mat.
is wrapped around the can and stored in the can case 9, and the stopper 10
It is fixed. The can case 9 also has an exhaust gas inlet 11 connected to the engine exhaust port and the muffler. Outflow ports 12 are provided respectively.

On the other hand, approximately lff1 is placed in front of the exhaust gas inflow side end of trap 1.
A wire mesh 13 of about 30 meshes of nichrome wire is placed with a gap of m to cover the entire surface of the trap 1. Electrodes 14 are attached to both ends of the wire mesh 13, and power is supplied from a battery (not shown).

Next, the operation of the configuration of this embodiment will be explained. First, normal filtration operation will be explained. Exhaust gas containing carbon-based particulates discharged from the diesel engine enters the can case 9 through the exhaust gas inlet 11. Can case 9
The exhaust gas entering the trap 1 enters the inlet channel 6 of the trap 1 after passing through the mesh of the wire mesh 13. When this exhaust gas passes through the wire mesh 13f, relatively large particles are caught in the eyes of the wire mesh 13 and deposited on the surface. On the other hand, the exhaust gas entering the inflow channel 6 passes through the ceramic wall 2,
Enter the leaked Chanfulua. At this time, very small particles that were not captured by the wire mesh 13 are collected on the surface of the ceramic wall 2 on the inlet channel e side. Therefore, the exhaust gases entering the outlet channel 7 are clean exhaust gases, which exit into the carrier case 9, enter the muffler through the outlet 12, and are discharged into the atmosphere.

Next, generation operation for incinerating accumulated particles will be explained. If the filtration operation continues for a long time, particulates will accumulate in the trap 1, increasing back pressure and reducing the efficiency of the diesel engine. At this time, a current of about 2 OA is applied from the electrode of the wire mesh 13.

The nichrome wire of the wire mesh 13 that is energized becomes red hot, and the fine particles deposited on the surface are ignited. First, the combustion propagates in the plane of the wire mesh. Thereafter, a separation phenomenon occurs between the ignited particles and the wire gauze, and they become sparks and fly into the inflow channel e of the trap 1 by the exhaust gas, causing secondary ignition of the particles deposited there. The combustion is then transmitted throughout the trap.

As a result, combustion spreads throughout the trap at once, ensuring regeneration without the fire going out midway through.

Next, other embodiments of the present invention will be described.

A stainless steel wire mesh is used instead of the nichrome wire wire mesh 13, and glow heaters are installed in spots at several locations on the surface of the wire mesh. In this embodiment, as in the above, combustion spreads to the surface of the wire mesh during regeneration, becomes sparks, and causes secondary ignition within the trap.

Effects of the Invention In the present invention, a wire mesh is placed in front of the trap, the particles accumulated on the wire mesh are first ignited, and this is used as an ignition source to burn the particles in the trap, so that the combustion reaches the entire trap and is reliable. Regeneration can be performed. Also, conventionally,
Partial combustion created a large temperature difference inside the trap, which caused cracks due to thermal stress, but this was also prevented.

[Brief explanation of drawings]

The figure is a longitudinal sectional view of a diesel exhaust gas purification device according to an embodiment of the present invention. 1...Trap, 4...Honeycomb structure, 6...Plug, 8...Buffer material, 9
...Can case, 13... Wire mesh, 14.
·····electrode.

Claims (3)

[Claims] (1) A diesel exhaust gas purification device comprising a ceramic trap that collects carbon-based particulates in exhaust gas, and a wire mesh covering the exhaust gas inflow side end of the trap. (2) The diesel exhaust gas purification device according to claim 1, which is a trap in which a cell end of a ceramic honeycomb structure and the other end of an adjacent cell are alternately closed with plugs. (3) The wire mesh is an electric resistance heater such as nichrome wire,
The diesel exhaust gas purification device according to claim 1, which has at least two electrical terminals in a plane and is connected to a power source.