JPH11182230A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of a diesel particulate filter and facilitate cleaning and replacement by providing exhaust gas inlet side with a pre-filter having catalyst combustion function and straightening function. SOLUTION: A casing part 3 as an exhaust gas inlet side 3 is provided with a pre-filter 1 having catalyst combustion function for forming a wash coat layer of aluminum powders which carries respectively 1 w.% of platinum and palladium in a honeycome catalyst carrier made of cordierite and straightening function. The pre-filter 1 is constituted so that adhered particulate is combusted with a catalyst, exhaust gas flowing as turbulent flow is straightened, and the particulate flows uniformly into a diesel particulate filter 2. Thus, durability of a diesel particulate filter can be improved and cleaning and replacement can be facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust gas purifying apparatus for purifying black smoke, particulates, carbon monoxide, and hydrocarbon contained in exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art Various attempts have been made to purify black smoke, particulates, carbon monoxide and the like contained in exhaust gas of a diesel engine. For example, Tokuho 4
According to No. -4019, a fluidized bed carrying a combustion catalyst is provided on the spherical ceramic surface downstream of the exhaust gas, and a fixed bed carrying an oxidation catalyst is provided on the foamed ceramic surface downstream of the fluidized bed. Means for heating the fixed layer is provided.

[0003] Further, regarding an exhaust gas purifying apparatus using a DPF (diesel particulate filter),
There have been proposed a device for supporting a combustion catalyst on a DPF and burning the captured particulates, and a device for providing a means for heating the DPF and burning the captured particulates.

[0004] However, the device using the spherical ceramic has a disadvantage that the pressure loss of the exhaust gas increases.
Further, in the apparatus using the DPF, it is disadvantageous that there is a partial variation in the amount of trapped particulates, and the durability of the apparatus is poor due to damage of the DPF due to thermal shock. Furthermore, in a casing using a flange,
It is not easy to clean or replace the DPF because the installation place is restricted.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a compact casing-free exhaust gas purifying apparatus which can improve the durability of a DPF, can easily clean and replace the DPF, and has no flange. It is an object.

[0006]

In order to achieve the above-mentioned object, according to the present invention, a pre-filter having a catalytic combustion function and a rectifying function is provided on the exhaust gas inlet side, and the attached particulates are subjected to catalytic combustion. At the same time, the exhaust gas flowing in the turbulent flow is rectified, so that the particulates flow uniformly into the DPF.

Further, in the present invention, the casing of the exhaust gas purifying apparatus is constituted by a cylindrical insertion type so that the DPF can be easily cleaned and replaced, and is a compact casing without a flange.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings based on embodiments. In FIG. 1, reference numeral 1 denotes a pre-filter, which is formed on a honeycomb catalyst carrier made of cordierite by forming a wash coat layer of alumina powder carrying 1 w% each of platinum and palladium.

[0009] Such a pre-filter has a catalytic combustion function, so that attached particulates can be burned at a relatively low temperature. In addition, the honeycomb structure has a function of rectifying exhaust gas flowing by turbulence. By this, the front entrance is 50% sealed.
The exhaust gas can flow into all the small holes of F at a uniform pressure.

Reference numeral 2 denotes a DPF (Diesel Particulate Filter), which is an unglazed trap filter in which cordierite honeycombs are alternately plugged at regular intervals. A catalyst carrying platinum, palladium and iridium, each containing 0.3% by weight, was used as a combustion catalyst for catalytic combustion.

Reference numeral 3 denotes a casing part on the exhaust gas inlet side, an outlet side casing part 4 is inserted, and both are fixed by bolts and nuts 6. Reference numeral 5 denotes a cushion material for protecting the ceramics 1 and 2, which is formed by knitting a thin stainless steel wire.

[0012]

Since the present invention is configured as described above, it has the following effects.

By providing a pre-filter, the DPF
At the same time as the amount of particulates flowing into the DPF is reduced, the rectified exhaust gas flows uniformly, so that the durability of the DPF can be significantly improved.

Further, since the casing of the apparatus can be formed into a cylindrical insertion system and the flange can be omitted, cleaning and replacement of the DPF can be easily performed, and restrictions on an installation place can be reduced. It can be easily attached to

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an exhaust gas purification device.

[Explanation of symbols]

 Reference Signs List 1 Pre-filter 2 DPF (diesel particulate filter) 3 Casing part (gas inlet side) 4 Casing part (gas outlet side) 5 Cushion material 6 Bolt, nut

Claims (2)

[Claims] 1. An exhaust gas purifying apparatus using a DPF (diesel particulate filter), wherein the exhaust gas purifying apparatus has a pre-filter having a catalytic combustion function and a rectifying function on an exhaust gas inlet side. 2. The exhaust gas purifying apparatus according to claim 1, wherein the casing includes an inner cylinder and an outer cylinder each having a cone portion and a connection pipe portion, and the inner cylinder is inserted into the outer cylinder and fixed at an arbitrary position. Exhaust gas purifier that makes it possible and eliminates the need for a flange.