JPS61223215A - Regenerating method for filter member for collectively catching fine particle - Google Patents

Abstract

PURPOSE:To improve regenerating efficiency of a filter member and prevent its melting loss, by allowing exhaust gas to flow detouring around the filter member and supplying air and exhaust gas, which maintain a collectively caught fine particle to an ignitionable and combustible temperature, to an inlet passage when the captioned filter member is regenerated. CONSTITUTION:When an engine 1 is in normal operation, exhaust gas from the engine 1 is allowed to flow from an exhaust pipe 15 into a vessel 3 of a fine particle collecting catcher A and flow out from a flow outlet 3b via a filter member 4. And if a difference between pressures before and after the filter member 4 increases to a predetermined value or more by blocking said member 4, a control circuit 7 electrifies an electric heater 5 through a relay 10 to be red heated. The method closes an opening and closing valve 6 while opens 13, 14 further regulates openings of flow regulating valves 18, 19 in accordance with an engine speed. Then the exhaust gas, bypassing the filter member 4, passes through an exhaust pipe 11, and a part of the gas, being allowed to flow reversely in the filter member 4, is discharged via exhaust pipes 15, 12. In this way, the method, increasing a temperature of the exhaust gas, efficiently performs destruction by fire of fine grain.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a filter member for collecting particulates in exhaust gas, particularly diesel engine exhaust gas, which burns and removes the particulates collected in the filter member. The present invention relates to a method for regenerating the filter member.

(Prior art) The amount of unburned carbon particles contained in the exhaust gas emitted from a diesel internal combustion engine is 1% compared to that of a gasoline engine, etc.
It reaches nearly 00 times the amount. In addition, as the number of diesel vehicles has been increasing in recent years, it has become necessary to take immediate measures to reduce unburned carbon particles. Part 1
One method is known from US Pat. No. 4,276,071, in which exhaust gas is purified by collecting unburned carbon particles using a filter member made of a porous ceramic honeycomb structure. It is also known that with this method, as the mileage of the vehicle increases, carbon buildup progresses and the pressure loss increases accordingly, so it is necessary to remove the accumulated carbon particles in some way and regenerate the filter member. ing. In other words, as the accumulation of particulates on the surface of the filter member progresses, the ventilation resistance of the filter member increases and engine output decreases, or clusters of particulates begin to fall off the surface of the filter member, causing the filter member to no longer function as a filter. descend. Since most of the particulates deposited on the filter member are carbon particles containing some fuel components, they can be removed by combustion.

Therefore, conventionally, as described in JP-A-58-170516, an electric heater device is installed on the exhaust gas upstream side of the filter member, and the particulates collected by the heater device are indirectly heated. I try to burn it.

FIG. 6 schematically shows the installation relationship between the heater device and the filter member, as well as a portion of the filter. The filter member has a plurality of inlet passageways 41 and an outlet passageway 42 through a plurality of porous walls, as described in the aforementioned U.S. Pat. No. 4,276-071;
The inlet passage 41 has one end closed and the other end open, while the outlet passage 42 has one end open and the other end closed.

Therefore, the exhaust gas entering from the inlet passage 41 is transferred to the porous wall 4.
The outlet passageway 42 is reached through the hole No. 3, and the outlet passageway 42 is reached through the porous wall 43, where the porous wall 43 collects particulates in the exhaust gas.

The electric heater 5 indirectly heats the particulates P collected on the entrance passage 41 side of the porous wall 43, and the particulates P are burned and removed by the heat of the heater 5 and the heat of the exhaust gas.

(Problems to be Solved by the Invention) In the above conventional example, as can be understood from FIG. Become.

Therefore, when the amount of collected particulates P is small, the above-mentioned escape of combustion heat makes it difficult for the combustion heat to propagate to the downstream area of the inlet passage 41, and as a result, the downstream area of the filter member Then, the regeneration will not be sufficient.

On the other hand, since the combustion heat passes through the porous wall 43 as described above, if the amount of collected particles is large and the combustion heat is high, the combustion heat may exceed the melting point of the material of the filter member.

(Means for Solving the Problems) Therefore, the present invention, when burning and regenerating the particulates collected in the filter member, bypasses the exhaust gas to the filter member, and ignites the particulates. Air or exhaust gas maintained at a temperature suitable for combustion is supplied from the outlet passage of the filter element through the holes in the porous wall to the inlet passage.

(Function) According to the present invention, the air or exhaust gas enters the outlet passage and then exits the inlet passage through the holes in the porous wall. The fine particles collected on the inner wall of the passage (the porous wall group described above) are ignited and burned, but the heat of combustion does not escape to the outlet passage through the pores of the porous wall, as in the conventional case. The heat of combustion is propagated downstream of the inlet passage and can also burn particulates downstream.

On the other hand, during such regeneration, the inner wall of the outlet passage has a lower temperature than the inner wall of the inlet passage due to the flow of air or exhaust gas, and the combustion heat in the inlet passage passes through the holes in the porous wall to the outlet passage. Therefore, the porous wall is prevented from being melted and damaged by combustion heat.

(Effects of the Invention) In summary, the present invention has excellent effects in that it has good regeneration efficiency and can prevent erosion of the filter member.

(Example) The present invention will be explained in detail below using specific examples.

In FIG. 1, a particulate collector A according to the invention is connected to an exhaust manifold pipe 2 of an internal combustion engine, in particular a diesel engine l. This device A is equipped with a metal container 3 having an exhaust gas inlet 3a and an exhaust gas outlet 3b communicating with an exhaust manifold pipe 2, and a filter member 4 for collecting particulates inside the container 3. - It has an electric heater 5 stretched inside the container 3 on the exhaust gas outlet side. The electric heater 5 is made of, for example, a metal wire, and is used to regenerate the filter member 4 by igniting and burning the particulates collected in the filter member 4. The electric heater 5 is energized by the battery 6 and is connected to the control circuit. 7 and relay 10. A signal from a differential pressure sensor 8 that measures the pressure loss of the filter member 4 and a signal from a rotation speed sensor 9 that detects the rotation speed of the engine are input to the control circuit 7 .

An exhaust pipe 11.12 is installed which bypasses the device A described above. An on-off valve 13.14 for opening and closing the inside of the pipe 11.12 is rotatably installed in the exhaust pipe 11.12.

On the other hand, the exhaust pipe on the inlet side of container 3! An on-off valve 16 for opening and closing the inside of the pipe 15 is rotatably installed in the pipe 5 . Also,
In the exhaust pipe 17 on the outlet side of the container 3, flow 1 regulating valves 18 and 19 are installed to adjust the flow rate of exhaust gas inside the pipe 17.

The operation of the above-mentioned on-off valves 13, 14, 16 and regulating valves 18, 19 is controlled by the control circuit 7 in the same way as the energization control of the electric heater 5. At the same time as the energization signal to the electric heater 5 is issued from the control circuit 7, the on-off valve 13.1
A valve opening signal is issued to the on-off valve I6, and a valve opening signal is issued to the on-off valve I6. On the other hand, a valve opening signal is also issued to the flow rate regulating valves 18 and 19, and a signal is issued to the valves 18 and 19, which has a valve opening degree that corresponds to the rotation speed of the engine 1.

That is, when the rotation speed is higher than the set value, a signal is issued to reduce the opening of the valve 18 and increase the opening of the valve 19, and on the other hand, when the rotation speed is lower than the set value, the reverse relationship or valve opening is generated. It is designed to emit a signal that becomes the same.

Note that when the differential pressure across the filter member 4 is below a predetermined value, that is, when the filter member 4 is new, the control circuit 7 fully opens the valves 13.14 and 16.1 after regeneration.
8.19 Sends a signal to open fully. These valves 13.1
4.16.18, [9] The drive source may be, for example, a vacuum motor or an electromagnetic solenoid.

Next, the detailed structure of the filter member 4 will be explained. In FIGS. 2 and 3, the filter member 4 is
It has a number of inlet passages 41 and outlet passages 42, with a number of porous walls 43 located between these passages 41,42. The inlet passage 41 is open at one end and closed at the other end, and the outlet passage 42 is closed at one end and open at the other end. Each aisle 41.42
The closed end of is constituted by a closure material 44.

The porous wall 43 has pores to allow exhaust gas to flow between the inlet passage 41 and the outlet passage 42 . When the filter member is attached to the exhaust system of an internal combustion engine, exhaust gas entering the inlet passage 41 passes through the pores of the porous wall 43. Fine particles are collected by the pores and the inner wall surface, and the purified exhaust gas is discharged through the adjacent outlet passage 42.

Further, the filter member as described above is manufactured, for example, by the following manufacturing method.

A binder such as methylcellulose, a liquid such as water, and additives for forming pores are added to ceramic raw material powder such as cordierite raw material starting from talc, chikara, olin, alumina, etc., and the mixture is kneaded using a kneader or other kneader. to adjust the extrusion molding material.

This extrusion material is extruded to form a lattice-like porous wall, and a molded body having a shape in which a large number of passages are provided inside is created. Next, after heating and drying this, the openings of the passages on one end surface of the molded body are closed every other time in a grid pattern with the above-mentioned kneaded material to an appropriate thickness. Further, the remaining passages are similarly closed on the other end surface different from the aforementioned closed end surface. The molded body obtained as described above is dried and fired at an appropriate temperature for an appropriate time to obtain a filter member having a honeycomb structure as shown in FIGS. 2 and 3. Additives for forming the pores of the porous wall include substances that produce a liquid phase by eutectic or melting at below the ceramic firing temperature, such as iron powder, copper powder, and nickel powder, or carbon, wax, etc. Combustible or volatile materials are used and their particle size and type can be varied1 to form porous walls with the desired pores.

Next, the operation of the above configuration will be explained. In FIG. 1, at the time of initial collection of the filter member 4, the on-off valve 13
．． 14 is fully closed, the on-off valve 16 and the flow rate adjustment valve 18.1
9 is fully open. As a result, the exhaust gas from the engine 1 passes through the exhaust pipe 15, flows into the container 3 from the inlet 3a, passes through the filter member 4, and flows out from the outlet 3b, and the particulates in the exhaust gas are removed from the filter member. Collected by 4.

Next, when the filter member 4 is clogged and the control circuit 7 determines that the differential pressure across the filter member 4 has reached a predetermined value or more, the circuit 7 sends the electric heater 5 to the relay 10.
An energizing signal is issued, and the electric heater 5 is energized and becomes red hot.

On the other hand, the electric signal from the control circuit 7 causes the on-off valve 16 to be fully closed, the exhaust pipe 15 to be closed, and the on-off valve 13.14 to close the exhaust pipe 15.
is fully opened and the exhaust pipes 11 and 12 are opened. Further, the opening degrees of the flow rate regulating valves 18 and 19 are adjusted according to the engine speed.

Therefore, the exhaust gas bypasses the filter member 4 and passes through the exhaust pipe 11, and a portion passes through the exhaust pipe 17 and passes through the filter member 4.
The gas flows backward through the exhaust pipe 15 and exhaust pipe 12 and is discharged to the atmosphere. Further, a part of the exhaust gas passing through the exhaust pipe 11 is directly released into the atmosphere by the regulating valve 18.

Then, a part of the exhaust gas that flows back to the outlet 3b of the container 3 is heated by the electric heater 5 to, for example, 650°C to 800°C and becomes a high temperature, and as shown in FIG. Inlet passageway 41. through the hole. is discharged.

Therefore, since the heat of combustion of the particulates P propagates within the entrance passage 41, the particulates P collected on the inner wall of the passage 41 are reliably burned away.

Furthermore, since the temperature of the exhaust gas heated by the electric heater 5 is lower than the combustion heat of the particulates P, it is possible to cool the porous wall 43 when passing through the porous wall 43 and prevent the wall 43 from melting away. can.

FIG. 5 shows another embodiment of the present invention. In this embodiment, when the filter member 4 is regenerated, air is blown out from the air introduction pipe 22 to the outlet 3b of the container 3 via the pump 21. is heated by an electric heater 5 and introduced into the filter member 4. Therefore, in order to prevent backflow of exhaust gas, the exhaust pipe 17 is fully closed by the on-off valve 20 during regeneration. The rest of the configuration is the same as the previous embodiment.

Next, specific experimental data will be shown.

Example 1 Cordierite filter member (diameter 1.17 mm,
130 mm in length) was attached to the exhaust system of a diesel car as shown in Figure 5, and 30 g of fine particles were collected. Thereafter, while flowing 30 tons of air from the air introduction pipe 22 at a rate of 1001/min, 2 kW of power was applied to the electric heater 5 for 2 minutes, and the regeneration of the filter member 4 was completed in 5 minutes from the start of zero current application. The filter member 4 was cut and the inside was investigated, but no melt damage or crank was found.

Comparative Example 1 After collecting 28 g of fine particles on the same filter member as in Experimental Example 1, an electric heater was installed on the inlet side of the filter member as in the conventional example, and 100 g of particles were collected on the same filter member as in Experimental Example 1. /min air was introduced into the inlet side of the filter member, and 2 kW of power was applied to the electric heater for 2 minutes.

Although the regeneration of the filter member was completed in 4 minutes after the start of energization, the inside of the filter member was melted and damaged from about 1/3 of the inlet side to the outlet side, making it unusable.

Experimental Example 2 5g of fine particles were collected in the same filter member as in Experimental Example 1, and the exhaust gas at 200°C was pumped through the exhaust system shown in Figure 1 at 50°C.
Power was supplied from the outlet side of the filter member at a rate of 17 minutes, and 2 kW of power was applied to the electric heater for 2 minutes. The filter member was completed in 4 minutes from the start of energization. It was found from the change in weight of the filter member that 90% of the collected particles were burned. When the filter member was cut and examined, one to two cells at the outermost collecting part of the filter member remained unregenerated.

Furthermore, there was no damage such as melting damage or cracks in the regenerated filter member.

, Comparative Example 2 5 g of fine particles were collected on the same filter member as in Experimental Example 2, an electric heater was installed on the inlet side of the filter member, and 200 g of fine particles were collected.
50 °C exhaust gas from the inlet side to the outlet side of the filter member.
2 kW of power was applied to the electric heater for 2 minutes while flowing at a rate of 1/min. After one energization, the exhaust temperature rose for 3 minutes, but after 5 minutes, the temperature was the same as before energization, so the filter The parts were investigated. Based on the weight change of the filter member, 25% of the particles were burned. When I cut it and inspected it, I found that the regenerated part was up to 1/3 from the inlet of the filter member.
It was playing in a parabolic manner. In the present invention, the filter member may be made of ceramic having a skeleton of a three-dimensional network structure, and it is more effective if a catalyst such as PL-Rh is supported near the heater in the outlet passage of the filter member. can burn fine particles. Furthermore, in the above embodiment,
Although a metal wire heater is used as the electric heater device, it is also possible to use a heater made of a ceramic material that generates heat when energized.It is also possible to supply hot air without using an electric heater device.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing one embodiment of the present invention, Fig. 2 is a front view showing the filter member in Fig. 1, Fig. 3 is a cross-sectional view taken along line nn in Fig. 2, and Fig. 4 is a main block diagram. FIG. 5 is a sectional view showing another embodiment of the invention, and FIG. 6 is a sectional view showing a conventional example. 4... Filter member, 5... Electric heater, 41...
- Inlet passage, 42... Outlet passage, 43... Porous wall.

Claims (1)

[Claims] an inlet passageway that is open at one end and closed at the other end; an outlet passageway that is closed at one end and open at the other end; and a porous wall located between the inlet passageway and the outlet passageway; In the filter member for collecting particulates, which allows exhaust gas to flow between the inlet and outlet passages, the exhaust gas is allowed to flow from the inlet passage to the outlet passage through holes in the front porous wall. When the porous wall collects particulates in the exhaust gas and ignites and burns the collected particulates to regenerate the filter member, the exhaust gas is bypassed to the filter member, and the outlet of the filter member A method for regenerating a filter member for collecting particulates, comprising supplying air or exhaust gas maintained at a temperature capable of igniting and burning collected particulates from the passageway to the inlet passageway through the holes in the porous wall.