JPS5999019A - Exhaust-gas purifying apparatus for diesel engine - Google Patents

Abstract

PURPOSE:To prevent clogging of a filter by capturing particulates contained in exhaust gas efficiently and burning the captured particulates by a catalyst by disposing a filter with catalyst consisting of roughly woven ceramic fiber on the upstream-side surface of a fine filter. CONSTITUTION:An exhaust-gas purifying apparatus 3 is disposed in an exhaust manifold 2 of a Diesel engine 1. The apparatus 3 is constituted by fixing a punching metal 5 and a ring stay 6 to the inside of a cylindrical body 4 and inserting a fine filter 7 made, for instance, of ceramic foam with no catalyst and a filter 8 with a catalyst in the form of a roughly woven fabric of silica fiber or the like between the punching metal 5 and the ring stay 6, such that the filter 8 is located on the upstream side of the filter 7. With such an arrangement, it is enabled to capture particulates consisting mainly of carbon in the exhaust gas efficiently and to prevent clogging of the filters by burning the captured particulates by the aid of the catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas purification device for a diesel engine that removes particulates (particulate matter) whose main component is carbon from exhaust gas.

Conventional purifying devices of this type include those in which particulate notes are collected using a filter, cyclone, or the like provided in the exhaust system. Also, this particulate rate collecting means is installed near the exhaust manifold, and the collected particulates are combusted by the heat of the exhaust gas.

However, when a filter is used, clogging occurs, and when a cyclone is used, the particulate rate is light and small, resulting in incomplete collection.

Also, if the particulate rate is filtered with a simple filter,
A layer of tscutiki rate was formed on the surface of the filter, which is the one that is best filtered, and this was a major cause of an increase in pressure loss and had an adverse effect on durability. Furthermore, in order to burn the collected particulates using the heat of the exhaust gas, the exhaust gas temperature needs to be over 600℃.
When vehicles are driven around town, there are almost no operating conditions in which the exhaust gas temperature exceeds 600°C, and therefore, the collected gas and ticulates are not combusted and end up clogging the filter. . In this case, a filter with a catalyst has a certain effect on incinerating particulates, but there is a problem of emitting sulfate, and the amount of emitted particulates tends to increase.

An object of the present invention is to provide an exhaust gas purification device for a diesel engine that eliminates the drawbacks of conventional devices, efficiently collects particulate matter, and stably collects and purifies particulate matter even during general city driving. It is in.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows the first embodiment, where 1 is a diesel engine, 2 is an exhaust manifold, 3 is an exhaust gas purification device, 4 is a cylindrical body, and 5 and 6 are 79-inch metals and rings fixed to the body 4 by spot welding, respectively. Between this punching metal 5 and the ring stay 6 on the stay, there is a fine particulate filler 7 made of ceramic, Kutuohm, wire mesh, or foamed steel without a catalyst, and on the upstream surface of the filter 7 there is a filter. A closely spaced tickrate filter 8 is inserted. Also arrow A
is the direction of exhaust gas flow.

Next, the operation of the above embodiment will be explained. In the present invention, a thin catalytic rate filter 8 with a catalyst is placed on the particulate filter 7 without a catalyst, and the particulate rate accumulated in these filters 7.8 is incinerated by the catalyst 5, and the filter is removed. This prevents clogging and improves durability. On the other hand, because the catalyst layer is thin, almost no gas is generated, and sulfate emissions are also small.

FIG. 2 shows a second embodiment of the combination filter (7
, 8) are interposed in series from upstream to downstream in the exhaust manifold, and the particulate filter 7a does not have a catalyst.

The filters 7b and 7c are arranged so that their meshes gradually become finer as they move from upstream to downstream, and catalyst filters 8a, 8b,
8c has rougher lines than at least the filters on the downstream side among the above-mentioned filters. Therefore, the particulates are collected at dispersed locations, and the particulates can be efficiently collected and sequentially incinerated by the catalyst, thereby improving the durability of the purification device.

As described above, the diesel engine exhaust gas purification device according to the present invention has 1. In the exhaust gas passage, one or several sets of purifiers combining particulate rate filters with no fine-mesh catalysts are arranged in series, and the filters become finer from upstream to downstream. With this structure, particulates can be efficiently collected and particulates can be stably collected and purified even during general city driving.

[Brief explanation of drawings]

Fig. 1 shows a first embodiment of the present invention, which is a block diagram of a diesel engine exhaust gas purification device including a particulate filter with a catalyst and a particulate filter without a catalyst, and Fig. 2 shows a second embodiment of the same. It is a block diagram of the same apparatus when there are multiple sets of both said filters. 2...Exhaust gas passage, 3...Exhaust gas purification device, 7゜7
a+7b, 7c...Fine particulate filter without catalyst, 8+8a+8b+8c...
Coarse particulate filter with catalyst.

Claims (2)

[Claims] (1) A particulate eye 2 letter (7) installed in the exhaust gas passage of the engine, and the upstream surface of the filter are thinly covered with ceramic fibers woven with a slightly rougher opening than the above filter. 1. An exhaust gas purification device for a diesel engine, characterized in that it is equipped with a woven cloth-like catalyst-attached filter (8) and at least one set of Fino carbon fibers. (2) The filter set (7, 8) is a lower device than the upstream side.