JPH0540250Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This application is directed to the exhaust gas emitted from a diesel engine,
The present invention relates to an exhaust purification device used to treat particulates.

[Conventional technology]

Exhaust gas discharged from diesel engines contains fine particles consisting mainly of carbon particles. Such particles need to be captured before they are released into the atmosphere. Therefore, a heat-resistant filter having micropores is used as a trapping means. However, microporous filters become clogged early and cannot withstand long-term use. Therefore, an exhaust gas purification device has been proposed in which when the filter becomes clogged, the captured particles are incinerated with exhaust heat to regenerate the filter function. An example of this is shown in FIG. 2. The exhaust gas purification device includes a filter section 9 in which a heat-resistant filter 4 is disposed inside a case 3 provided with inlets and outlets 1 and 2, and a burner device 5 provided on the inlet side of the filter section. It consists of The burner device 5 includes an ignition section 6, a fuel injection section 7, and an air supply section 8.

Exhaust gas from a diesel engine flows into the device through an inlet 1, and the fine particles it contains are captured and purified by a heat-resistant filter 4. When the heat-resistant filter 4 becomes clogged, this is sensed and the burner device 5 is started. That is, the ignition section 6 ignites, fuel is supplied from the fuel injection section 7, outside air is introduced from the air supply section 8, for example, by a compressor, and the mixture of air and fuel is ignited and combusted by the ignition section 6 to be exhausted. As a result, the temperature of the heat-resistant filter 4 is raised, and the captured fine particles are burned out.

[Problem that the invention attempts to solve]

However, in the burner device used in such a conventional exhaust purification device, outside air always flows in from the air supply section 8 during filter regeneration, so the burner device itself is cooled.
This has the drawback that under certain engine operating conditions, the air-fuel mixture may not burn, or a stable combustion state may not be obtained. Furthermore, providing an air supply section connected to a compressor or the like has the disadvantage of complicating the structure.

[Means for solving problems]

A filter is arranged in a case with an inlet and an outlet, and on the inlet side of the case there is an inner cylinder with a collision plate at one open end and a fuel injection nozzle at the other closed end, and an inner cylinder around the inner cylinder. In an exhaust purification system for a diesel engine, which has an outer cylinder and is further equipped with a burner device having an ignition means around a collision plate, one exhaust introduction pipe branching from the exhaust pipe is tangentially connected to the closed end side of the outer cylinder. The exhaust introduction pipe and the inside of the outer cylinder are provided in communication with each other, and the other exhaust introduction pipe is provided on the open end side of the outer cylinder, and an oxidation catalyst is attached to the filter.

[Effect]

When the engine is operating at a low load and the oxygen concentration in the exhaust is high, a burner device burns the mixture of oxygen and fuel in the exhaust to raise the exhaust temperature and heat the filter, burning out the captured particulates. The burner device does not function, and during high-load operation, the trapped particles are burned away by the heat of the filter itself, which is heated by the catalytic reaction.

〔Example〕

FIG. 1 shows an exhaust purification device 10 of the present invention installed in a diesel engine, and is composed of a filter section 11 and a burner device 12. The filter section 11 has a ceramic honeycomb-shaped filter 16 in which a large number of fine overflow passages are provided inside a case 15 having an inlet and an outlet 13 and 14 . The filter 16 is impregnated with and adhered to an oxidation catalyst such as Pt or Pa. The burner device 12 is provided on the inlet 13 side of the filter section 11 and includes a fuel injection section 17 and an ignition means 18. The burner device 12 has a collision plate 1 at one open end.
9, an inner cylinder 21 having a fuel injection nozzle 20 at the other closed end, and an outer cylinder 22 surrounding the inner cylinder 21, and an ignition means, that is, a spark plug 18, is provided around the collision plate 19. It is being Outer cylinder 22
An exhaust inlet pipe 23a is tangentially connected to the closed end side of the
However, there is also an exhaust introduction pipe 23 on the open end side of the outer cylinder 22.
b are provided respectively. Exhaust introduction pipes 23a, 23b
are two pipes branching from the exhaust pipe 24. One end of the exhaust introduction pipe 23a communicates with the case 15 of the filter section 11 through the outer cylinder 22, and the other end connects with the exhaust pipe 24 of the diesel engine. One end of the exhaust introduction pipe 23b communicates with the inside of the case 15 via the outside of the outer tube 22, and the other end is connected to the exhaust pipe 24.

In FIG. 1, the exhaust gas discharged from the diesel engine is connected to an exhaust pipe 24, exhaust introduction pipes 23a, 23
b, it reaches the burner device 12 and further flows into the filter section 11 through the inlet 13. In the filter section 11 , fine particles (mainly composed of carbon particles) in the exhaust gas are captured by a filter 16 .
CO, HC, etc. in the exhaust gas are chemically treated by the catalyst. Along with this, the filter 16 is heated. When the filter 16 reaches a predetermined clogging state, this is sensed and the spark plug 18 ignites.
At the same time, fuel is injected from the fuel injection nozzle 20, collides with the collision plate 19, is scattered around, and flows toward the filter section 11 while mixing with the exhaust flow flowing in from the exhaust introduction pipe 23a. In the presence of oxygen in the exhaust gas, the air-fuel mixture is ignited and combusted by the spark plug 18, warming the exhaust gas flowing in from the exhaust gas introduction pipe 23b and further heating the filter 16. When the heated filter 16 reaches a predetermined temperature, the fine particles captured by the filter 16 are burned out and the filter 16
The function of play. The above is an operation when the diesel engine is operating at a low load with a relatively large amount of residual oxygen in the exhaust gas.

During high-load operation, the amount of oxygen remaining in the exhaust gas is low and the air-fuel mixture often does not ignite or burn, but the filter 16 to which the catalyst is attached
The temperature rises due to the heat of reaction, and the fine particles captured by the filter are self-burned out.

[Effect of idea]

The exhaust purification device of the present invention uses a burner device to heat the filter during low-load operation when the amount of residual oxygen in the exhaust is high and burns out the captured particles, and the burner device is difficult to operate under conditions where there is no outside air inflow. During high-load operation, the heat of the filter itself, which rises in temperature due to the catalytic reaction, burns out the captured particles, making it possible to regenerate the filter throughout the entire engine operation without introducing outside air, making it possible to reduce the amount of outside air introduced. The accompanying disadvantages of poor combustion and complicated structure are eliminated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the exhaust gas purification device of the present invention, and FIG. 2 is a sectional view of a conventional exhaust gas purification device. 11... Filter section, 12... Burner device, 1
6... Catalyst impregnated filter, 17... Fuel injection part,
18... Ignition means, 23a, b... Exhaust introduction pipe.

Claims (1)

[Scope of utility model registration request] A filter is arranged in a case with an inlet and an outlet, and on the inlet side of the case there is an inner cylinder with a collision plate at one open end and a fuel injection nozzle at the other closed end, and an outer cylinder around it. In an exhaust gas purification device for a diesel engine, which has a cylinder and a burner device having an ignition means installed around a collision plate, one exhaust inlet pipe branching from the exhaust pipe is tangentially connected to the closed end side of the outer cylinder. An exhaust purification device for a diesel engine, characterized in that the exhaust introduction pipe is provided in communication with the inside of the outer cylinder, the other exhaust introduction pipe is provided on the open end side of the outer cylinder, and an oxidation catalyst is attached to the filter. .