JPH02153214A - Exhaust gas purifying device for diesel - Google Patents

Abstract

PURPOSE:To perform the removal of particulates with simplicity and a low cost by discharging exhaust gas from an ejector, thereby producing negative pressure to attract air and electrifying an electric heater to fire-burn the particulates. CONSTITUTION:During a normal run of a diesel engine, a four-way valve 10 is in the direction of having an exhaust pipe 9 shared with a filter connected port 11 and an air port 14 shared with a bypass pipe 12, respectively. At this time exhaust gas gets to a front portion in a pipe case 5 via a filter connecting pipe 11, then enters into cells 2 of a ceramic honeycomb structure 1 and passes through cell walls into a muffler connected port 8. Also, particulates included in the exhaust gas can not pass through the cell walls and so accumulated in the cells 2. To remove the accumulated particulates negative pressure is produced with suction effect of an ejector 13 to attract air from an air port 14 and an electric heater 7 is electrified to burn the particulates.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an exhaust gas purification device for purifying exhaust gas from a diesel engine, particularly for removing particulates (combustible particles such as soot) contained in the exhaust gas.

Conventional technology In order to remove particulates emitted by diesel engines and purify the exhaust gas, there is a method of installing a heat-resistant filter in the middle of the exhaust pipe and filtering the perf- iculates.This method is called beam generation. Therefore, old filters that have accumulated a certain amount of particulates should be incinerated to regenerate the filter cleanly and used repeatedly.In general, the exhaust gas temperature of diesel engines is low, so particulates cannot be burned as they are.

Therefore, should we raise the exhaust gas temperature by some method?
Alternatively, the ignition temperature of particulates must be lowered. One method of regeneration is to install a burner or electric heater upstream of the filter on the engine side, and use the heat to raise the particulates to the ignition temperature.

Problems to be Solved by the Invention However, if an attempt is made to ignite particulates with an electric heater or oil burner while engine exhaust gas is flowing into the filter, heat will be taken away by the exhaust gas. Therefore, a large capacity electric heater or oil burner is required to cover this.

To avoid this, there is a method of providing a thread path that bypasses the filter, cutting off the exhaust gas flowing to the filter during regeneration, and heating the filter. However, this requires a separate air supply for combustion of the particulate matter.

SUMMARY OF THE INVENTION Therefore, the present invention provides a diesel exhaust gas purification device that can perform refueling and 1-neration using an electric heater or an oil burner without installing a separate air supply device.

Means for Solving the Problems The technical means of the present invention for solving the above problems is to provide a bypass pipe that branches exhaust gas from the filter, and a bypass on-off valve that switches the inflow path of the exhaust gas at the branch point. An ejector is formed at the point where the outlet of the filter can and the outlet meet.

action The effects of the technical means of the present invention are as follows.

That is, the exhaust gas discharged through the bypass pipe to the confluence point with the outlet of the filter draws air into the filter by the suction effect of the ejector, and supplies air for regeneration to burn particulates.

EXAMPLE Hereinafter, an example of the diesel exhaust gas purification apparatus of the present invention will be described based on the attached 14 drawings.

FIG. 1 shows a longitudinal section of an exhaust gas purification device, in which 1 is a ceramic honeycomb structure having a large number of cells 2 inside. One ends of the cells 2 are alternately closed with plugs 3 to form a ceramic filter. Further, the ceramic honeycomb structure 1 is wrapped around its outer periphery with a cushioning material 4 having good heat insulation properties made of ceramic fibers hardened with an organic binder, and is housed in a cylindrical stainless steel can case 5. Stoppers 6a and 6b are welded to the inside of the can case 5 so as to be located at the front and rear of the ceramic honeycomb structure 1 so that the cushioning material 4 does not move. Further, the can case 5 has a conical cone-shaped diameter at the front, and an electric heater 7 as a heater is provided in the middle thereof. Further, the rear part of the can case 5 is narrowed into a conical cone shape, and is provided with a muffler connection port 8 connected to an exhaust muffler (not shown). On the other hand, an exhaust pipe 9 of a diesel engine (not shown) branches into a filter connecting pipe 11 and a bypass pipe 12 via a westward valve 10 midway. The filter connecting pipe 11 is connected to the can case 5.

In addition, the bypass pipe ■2 is drawn into the can case 5 at the rear of the ceramic honeycomb structure 1, and the muffler connection port 8
The ejector 13 is opened at the center shaft of the ejector 13. The four-way valve 10 is also connected to the air intake port 14, and when it rotates, exhaust gas from the engine is transferred to the filter connection pipe 1.
1 and the bypass pipe 12, and the filter connecting pipe 11 and the air port 14 can be communicated with each other. That is,
The four-way valve 10 constitutes a bypass opening/closing valve that switches the exhaust gas inflow path between the filter and the bypass pipe 12, and an air inflow valve that connects the air port 14 and the filter connection pipe 11.

Next, the operation of the configuration of this embodiment will be explained. First, the normal operation of the diesel engine will be explained.

The four-way valve 10 is located in a direction in which the exhaust pipe 9 and the filter connection port 11 communicate with each other, and the air port 14 and the bypass pipe 12 communicate with each other. At this time, exhaust gas from the engine reaches the front surface of the ceramic honeycomb structure 1 via the filter connection pipe 11. From here, the exhaust gas enters the cells 2 that are open to the front of the ceramic honeycomb structure 1, and there, it passes through the cell walls and enters the cells 2 that are open to the rear. At this time, particulates contained in the exhaust gas are deposited inside the cell 2 without being able to pass through the cell walls. On the other hand, the exhaust gas, which has been made clean by removing particulates, enters the muffler connection port 8 and is discharged to the atmosphere through the exhaust muffler.

This work of depositing particulates is continuously carried out over a period of 1 to 2 hours. When enough particulates have accumulated in the ceramic honeycomb structure 1, and if they accumulate any more, they will have a negative impact on the engine, the four-way valve 10 is rotated to remove the exhaust pipe 9 and the bypass pipe 1.
2, and the air port 14 and the filter connection pipe 11 are brought into communication. The exhaust gas then flows into the bypass pipe 12 and is discharged toward the muffler connection port 8 within the can case 5. At this time, a suction effect is generated at the ejector 13 formed by the outlet end of the bypass pipe 12 and the conical cone constriction portion of the can case 4, and negative pressure is generated at the rear of the ceramic honeycomb structure 1. This negative pressure causes air to be sucked into the ceramic honeycomb structure 1 from the air ports 14. At this time, when the electric heater 7 is energized, the particulates are ignited and continue to burn under air supply. This combustion residue and exhaust gas are released into the atmosphere through an exhaust muffler. This state is maintained for 10 minutes, and when all the particulates deposited within the ceramic honeycomb structure 1 are burned off, the interior returns to its original clean state. Then, first cut off the power to the electric heater 7, rotate the four-way valve 10 in the opposite direction,
The flow of waste waste flowing through the bypass pipe 12 is switched to the filter connecting pipe 11. Then it returns to normal operating condition.

In this way, when incinerating the particulates deposited within the ceramic honeycomb structure 1, that is, during regeneration, fresh air can be taken into the ceramic honeycomb structure 1 from the outside by using the energy of the exhaust gas.

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

FIG. 2 shows a longitudinal section of the exhaust gas purification device.

In this case, the ceramic honeycomb structure 1 has a cylindrical shape. Bypass pipe 12 includes ceramic honeycomb structure 1
It is drawn into the can case 5 in front of the can case 5. The ejector 13 is formed by passing through the inner cylinder of the ceramic honeycomb structure 1 and opening at the center axis of the muffler connection port 8 at the rear thereof. The operation of this embodiment is exactly the same as that of the previous embodiment. Moreover, a similar result can be obtained by using a small oil burner equipped with an oil supply device and an igniter instead of an electric heater as a heater for igniting particulates.

Effects of the Invention By using the exhaust gas energy from the engine to take in the air necessary for regeneration during regeneration, the present invention not only eliminates the need for an air supply device such as a fan (but also reduces the electricity consumption associated with it). Nothing (can be done.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views of a diesel exhaust gas purification device according to an embodiment of the present invention. 1... Ceramic honeycomb structure, 5... Can case, 7... Electric heater, 9... Exhaust pipe, 10
...Four-way valve, 12...Bypass pipe, 13...
・Cozector-14...Air vent.

Claims (3)

[Claims] (1) A can case connected to the exhaust pipe of a diesel engine, a filter that filters particulates stored in the can case, a bypass pipe that branches the exhaust gas without passing through the filter, and an inflow path for the exhaust gas that is connected to the filter. a bypass on-off valve for switching between the bypass pipe and the bypass pipe; an ejector provided at the confluence of the bypass pipe and the outlet of the can case;
It consists of an air inflow valve installed at the inlet side of the can case and a heater installed at the inlet side of the filter, and when the bypass on-off valve is switched to the bypass side, the air inflow valve is simultaneously opened to reduce the negative pressure caused by the ejector. A diesel exhaust gas purification device is characterized in that combustion air is taken into a can case, and particulates are ignited and combusted by a heater. (2) The diesel exhaust gas purification device according to claim 1, wherein the bypass on-off valve is a four-way valve, and also serves as the air inflow valve. (3) Consisting of a filter with a thick-walled cylindrical cross section and a bypass pipe inserted into the inner cylinder of the filter, at least the outlet of the can case is narrowed into a conical shape, and the filter is located on the central axis near the root of the cone. 2. The diesel exhaust gas purification device according to claim 1, wherein the ejector is configured by arranging the bypass pipe in the exhaust gas purifying device.