JPH059451Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Traditional field] The present invention relates to a diesel exhaust purification device.

[Conventional technology]

In order to prevent exhaust particulates contained in diesel engine exhaust gas from being released into the atmosphere, ideas have been made to place a filter in the middle of the exhaust pipe (for example, Japanese Patent Laid-Open No. 190626/1983) reference). In addition, exhaust particulates are captured by a filter,
It is known that after a predetermined clogging state is reached, a combustion regeneration process is performed using electric heating means or the like. In this case, there is a problem that the exhaust system is exposed to high temperatures, so it is known to reduce the ignition temperature of exhaust particulates by spraying additives such as copper compounds into the exhaust gas (for example, Unexamined Japanese Patent Publication 1987-
(See Publication No. 30521).

[The problem that the idea attempts to solve]

When additives are supplied into the exhaust gas, the ash content after combustion of the additives will accumulate on the filter, and since the ash content will not be combusted, this will also cause a pressure loss in the exhaust gas flow.
Fuel efficiency worsens. Further, when the additive is supplied into the exhaust gas, the distribution of the additive becomes localized, and there is a problem that it becomes ineffective against the exhaust particulates that aggregate into agglomerated forms. The present invention has been made to solve these problems.

[Means to solve the problem]

As a means to solve the above-mentioned problems, the present invention provides an additive supply device for supplying an additive that lowers the ignition temperature of exhaust particulates to the fuel supply system of a diesel engine. It is an open cell type,
To provide a diesel exhaust purification device characterized in that a filter made of a foam material is arranged so that ash after combustion of additives does not accumulate on the filter when the filter is regenerated.

[Effect]

Since the additive is supplied in the fuel system, even a small amount of additive is surely diffused and contained in each exhaust particle, and even in the case of agglomerated exhaust particles, the additive reaches the center. Because they exist, exhaust particulates ignite and disappear at low temperatures. In addition, by using an inherently large open cell type foam material, during regeneration of the filter, the ash after combustion of the additive passes through the filter and no ash is deposited on the filter. Furthermore, since the filter is an open cell type foam material that allows exhaust gas to penetrate over a long distance, even small-sized exhaust particles that are directly emitted without being collected by the filter can still supply additives to the fuel supply system. As a result, the catalytic action is fully activated while passing through the filter.
Exhaust particulates are completely purified and discharged.

〔Example〕

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

In Figure 1, 1 is a diesel engine, 2 is a diesel engine,
is the fuel tank. A known fuel supply system includes a fuel tank 2, a fuel supply pipe 3, and a fuel injection pump 4, and a fuel filter 5 and a fuel sedimenter 6 are arranged in the fuel supply pipe 3. 7 is a return pipe. On the other hand, an additive tank 8 is provided and connected to the fuel supply pipe 3 through an additive supply pipe 9. An additive supply pump 10 is arranged in the additive supply pipe 9 . The additive is appropriately selected from manganese, calcium, copper, lead, etc., and lowers the ignition temperature of particulates in the exhaust gas. The additive supply pump 10 mixes the additive into the fuel in an optimally small amount.

Exhaust pipe 1 connected from exhaust manifold 11
A filter 13 is placed in the middle of 2. The filter 13 is a filter made of an open cell type foam material shown in FIG. A blockable type honeycomb filter 14 shown in FIG. 3 is often used in diesel exhaust purification devices. In the blockable type honeycomb filter 14, exhaust gas flows from one cell 14a to the adjacent cell 14b through the partition wall between these cells as shown by arrow A, and the actual penetration distance l (i.e. time) is relatively short. It's getting smaller. That is, such a blockable type honeycomb filter 14 has a narrow mesh structure, and most of the exhaust particles are captured on the surface of the partition walls, and its structure is fundamentally different from that of the open cell type foam filter 13. It is something. Open-cell foam materials, also called open-cell foams, are made of continuously connected cells and have a relatively large three-dimensional network pore structure. Therefore, the length of the filter 13 made of an open cell type foam material is determined so that the exhaust gas can easily pass through the continuously connected air bubbles and the penetration distance L (i.e. time) of the exhaust gas is large. can do. Therefore, by using the filter 13 made of an open cell type foam material, combustion ash and exhaust particulates caused by additives can more easily penetrate the filter than in the case of the blockable type honeycomb filter 14. Increase in pressure drop can be suppressed to a low level. Furthermore, as mentioned above, a filter 1 made of an open cell type foam material is provided.
In No. 3, since the penetration distance L or the residence time is large, the exhaust particulates are easily ignited or oxidized by the additive, and by sufficiently burning in the filter 13, the amount of exhaust particulates discharged is reduced. For this reburning, the exhaust gas temperature needs to be 200 to 300℃ or higher due to the action of the additive, and the filter 13
is preferably located close to the exhaust manifold 11. On the other hand, when a blockable type honeycomb filter 14 is used, ash and the like are difficult to pass through and accumulate on the filter, resulting in an increase in pressure loss.

[Effect of idea]

As explained above, according to the present invention, the additive is added to the fuel in the fuel supply system, so that even a small amount of the additive is well diffused in the fuel, and is also well dispersed in the exhaust gas during the combustion stroke of the engine. The additive is distributed all the way to the center of the exhaust particles that adhere to the filter.
Lowers the ignition temperature of all exhaust particulates and completely re-burns them. Moreover, since the filter essentially uses a large open cell type foam material, it is possible to prevent the ash after additive combustion from accumulating on the filter during filter regeneration, thereby reducing the pressure loss of the exhaust gas. . Further, since a substantially large open cell type foam material is used, some of the exhaust particles with small particle diameters are not collected by the filter and are directly discharged.
However, even in such a case, according to the present invention, since the additive is mixed into the fuel supply system, the additive is distributed to the center of the exhaust particles, and the filter is an open cell type foam material, so the exhaust gas Due to two factors: a long residence time when the particulates pass through the filter, the exhaust particulates that are not captured by the filter are sufficiently oxidized and completely purified while passing through the filter before being discharged. Therefore, the exhaust gas purification performance is improved.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the diesel particulate purification device according to the present invention, Figure 2 is a schematic diagram of the foam filter in Figure 1, and Figure 3 is a conventional foam filter for comparison with the foam filter in Figure 2. 1 is a schematic diagram of a honeycomb filter. 1... Diesel engine, 2... Fuel tank, 3... Fuel supply pipe, 4... Fuel injection pump,
8... Additive tank, 9... Additive supply pipe, 12
...Exhaust pipe, 13...Filter.

Claims (1)

[Scope of utility model registration request] The fuel supply system of the diesel engine is equipped with an additive supply device that supplies an additive that lowers the ignition temperature of exhaust particulates. 1. A diesel exhaust purification device, characterized in that the filter is disposed in a foam material that prevents residual ash from being deposited on the filter.