JPH0424531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a ceramic member for collecting particulates of an internal combustion engine, for example, a diesel engine, which collects and purifies carbon particulates in the exhaust gas of the engine.

Conventionally, this type of device was disclosed in U.S. Patent No.
There is one described in the specification of No. 4276071. This is made of a ceramic filter member having a ceramic honeycomb structure, and a large number of passages extending in the axial direction of the filter member are alternately closed at the openings at both ends. Exhaust gas flowing in from the inlet side passes through the passage, flows into another passage adjacent to the passage through the pores in the partition wall, and flows out from the outlet side of the filter portion.

In the conventional honeycomb filter member described above, carbon particulates in the exhaust gas are captured while passing through the isolation pores that isolate the numerous passages, and the collected carbon particulates are burned and filtered through the filter. It is necessary to try to recycle the parts.

Therefore, an electric heater is required to burn off the carbon particles. It is conceivable to arrange this electric heater on the inlet side end face of the filter member.

An object of the present invention is to provide a manufacturing method that can securely hold the heater wire and provide an integrated configuration of the heater wire and filter member using a simple manufacturing method when combining a filter member and a heater wire. .

In order to achieve the above object, the present invention includes a step of impregnating a ceramic slurry into a porous organic material molded body that is burnt out by combustion and has a honeycomb shape, and a process of impregnating a ceramic slurry into a porous organic material molded body that is burnt out by combustion and has a cylindrical shape. a step of impregnating a ceramic slurry with a ceramic slurry;
a step of sandwiching an electric heater wire between two porous organic material molded bodies; and a step of pressing the molded body with the electric heater wire sandwiched therebetween onto an end surface of the honeycomb-shaped molded body impregnated with the ceramic slurry. and a step of firing the porous ceramic honeycomb filter member in the state, and by the firing step, the porous ceramic prefilter member having the heater wire built therein is integrated with the end face of the porous ceramic honeycomb filter member. It is.

Hereinafter, the present invention will be explained according to illustrated embodiments.

In FIG. 1, a particulate collector A according to the present invention is connected to an exhaust manifold pipe 2 of an internal combustion engine, particularly a diesel engine 1. In FIG. 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 gas collecting chamber 2. Inside the container 3, there is a filter member 4 having a honeycomb structure for collecting particulates. It has an electric heater 5 coupled to an end surface of the filter member 4 on the exhaust gas inlet side. The electric heater 5 is used to regenerate the filter member 4 by burning the particulates collected in the filter member 4, and energization by the battery 6 is controlled by a control circuit 7. A signal from a differential pressure sensor 8 that measures the pressure loss of the filter member 4 and a signal from a rotation sensor 9 that detects the engine speed are input to the control circuit 7.

Exhaust gas from the engine 1 flows into the container 3 of the collection device A from the inlet 3a, and passes through the filter members 10, 4.
and flows out from the outlet 3b. When the exhaust gas passes through the filter members 10, 4, carbon particles in the exhaust gas are collected by the filter members 4, 10 and removed.

As the collection of particulates progresses and the ventilation resistance of the filter member 4 increases, the differential pressure sensor 8 outputs a corresponding signal. The pressure difference between the upstream side and the downstream side of the filter member 4 detected by the differential pressure sensor 8 also changes depending on the engine speed. Therefore, the sensor circuit 7 calculates the true ventilation resistance of the filter member 4, that is, the collection density of particulates, from the signal from the differential pressure sensor 8 and the signal from the rotation speed sensor 9. Start energizing the heater 5. As a result, the heater 5 becomes red hot and the temperature rises to a temperature at which fine particles (mainly carbon) can be burned.

As the electric heater 5 becomes red hot, the fine particles are heated and burned. Combustion starts from the insertion part of the electric heater 5, and the combustion expands to the upstream side of the exhaust gas, and the amount of heat generated along the flow of the exhaust gas is transmitted to the downstream side of the exhaust gas, so that efficiency is increased to the downstream side of the exhaust gas. The combustion expands well. Therefore, if the electric heater 5 is placed at a position near the upstream end face where the particle density is maximum, that is, inside the prefilter member 10, ignition becomes easier and the filter member 4
It is possible to efficiently spread combustion over the entire area and remove the collected particulates. When the filter member 4 is regenerated by removing the fine particles and the ventilation resistance is reduced, the power supply to the heater 5 is stopped.
Of course, fine particles in the prefilter member 10 are also removed.

In the present invention, since the electric heater 5 is arranged inside the prefilter member 10, there is little heat loss such as radiation loss when the heater 5 is heated. As a result, the filter members 10 and 4 can be regenerated with less electric power. Further, since the electric heater 5 is arranged at a position where the density of particulates collected by the prefilter member 10 is maximum, ignition and combustion efficiency is good. Furthermore, since the electric heater 5 is completely fixed inside the prefilter member 10, its mechanical strength can also be increased.

Next, the specific configuration of the device of the present invention will be explained based on some examples.

In FIGS. 2 to 5 showing the first embodiment, the metal container has two container pieces 30 and 3 as shown in FIG.
It is a two-part type constructed by caulking the ends of 0a together with a press, and the cross-sectional shape is oval or circular. The plump end and downstream end of this container 3 are constricted to form an inlet 3a and an outlet 3b for exhaust gas, respectively.

A metal wire net 31 having heat resistance as a thermal cushion material is disposed inside the container 3, and a honeycomb filter member 4 and a prefilter member 10 are disposed inside thereof. The filter member 4 has a porous ceramic honeycomb structure having a three-dimensional mesh skeleton, and the prefilter member 10
is also made of porous ceramic having a similar skeleton, and the outer periphery of both members 4 and 10 on the 10 side is covered and protected by a strength member 43 made of fine porous ceramic.

The filter member 4 comes into contact with a fixing plate 32 fixed to the inner surface of the container 3, and is moved downstream. A heat-resistant seal member 33 is disposed between the wire net 31 and the fixed plate 32 so that all of the exhaust gas passes through the inside of the filter members 4 and 10. The filter member 10 is composed of two filter members 101 and 102, and the electric heater 5 is sandwiched and fixed between the two filter parts 101 and 102. Further, this filter member 10 is integrally joined to the inlet side end surface of the honeycomb filter member 4.

The degree of roughness of the porous ceramics of the filter parts 101 and 102 should be determined appropriately, taking into consideration their axial length and cross-sectional area, so that fine carbon particles can be collected and the ventilation resistance will not become extremely large. Can be selected. Generally, about 5 meshes to 17 meshes are used, but the number is not necessarily limited to this range.

FIG. 6 shows the filter section 10 used in this example.
1,102 (cylindrical shape with a diameter of 12 cm, mesh roughness of 13 mesh) showing the change in the carbon particulate collection density in the length direction. According to this, it can be seen that the carbon collection density is maximum at a position 10 mm in the length direction from the upstream end face. This depends on the coarseness of the filter portions 101 and 102, and is 30 mm to 3 mm when there are 5 to 20 meshes. In this way, the position where the carbon collection density is maximum can be determined by experiment according to the coarseness of the filter parts 101 and 102, and the position showing the maximum density (from 3 mm to the entrance of the filter member 10) can be determined by experiment. 30
The thickness of the filter member may be selected such that the electric heater 5 is placed between For example, when the coarseness of the filter member 10 is 20 meshes, approximately 3
mm, when the coarseness of the 10th mesh of the filter member is 8 mesh, it is approximately 10mm, and the coarseness of the 10th mesh of the filter member is 5 mm.
When using mesh, select approximately 30mm. Therefore, the filter member 1 that satisfies this value should be
The axial length and mesh coarseness of the filter portions 101 and 102 constituting 0 may be selected. Further, the axial length of the prefilter member 10 is determined depending on the relationship between the honeycomb filter member 4 and the ventilation resistance, but it is preferably about 1/3 of the axial length of the honeycomb filter member 4.

Both ends of the heater wire 5a of the electric heater 5 pass through the filter member 10 and are connected to terminals 51 and 52 of a terminal portion 50, and are connected to the control circuit 7 (FIG. 1) via these terminals. Heater wire 5a
At this time, both ends of the heater wire 5a are bent to form a small ring and provided with stress absorbing portions 5b, so that the grooves between the heater wire 5a and its terminals 51 and 52 are not disconnected even by vibration or the like. Ru. Terminal part 5
0, as shown in FIG. 3, a base body 53 is fixed by welding on the outer surface of the container 3, and terminals 51 and 52 are disposed inside the base body 53 by rotating an insulating pair 54. And packing 55 made of insulating material
is installed, and the cover 56 is attached to the base 53 with screws 57.
Fixed.

The honeycomb filter member 4 is obvious from the structure shown in FIG. 2, but when viewed obliquely, it has the structure shown in FIG. 5. That is, in both figures, the filter member 4 has a honeycomb structure in which a large number of passages 4a are separated by a large number of partition walls 4b, and both ends of the large number of passages 4a are alternately closed at every other passage. (In Fig. 5, the shaded area is the closed area).
Therefore, the exhaust gas that has entered the filter member 4 is
As shown by the arrow in FIG. 2, it passes through the partition wall 4b.

Next, a method for manufacturing the honeycomb filter members 4, 10 will be described in detail. First, a mold for making the honeycomb filter member 4 will be described.

FIG. 7 shows a mold container used in the present invention, with FIG. 7a being a plan view and FIG. 7b being an axial sectional view. The mold container part 20 is composed of an end face 22 and a side wall 23, each of which has a columnar member 21 having a square cross section smaller than the area of the compartment fixed vertically in every other compartment divided into a base shape, and the other end faces are open. ing. On the other hand, FIG. 8 shows a mold lid used in the present invention, with FIG. 8a being a plan view and FIG. 8b being an axial sectional view. The mold lid part 60 is composed of a flat plate lid 62 to which a columnar member 61 is vertically fixed, similar to the mold container part 20 described above. The columnar members 61 are attached to grid-like sections of the mold container section 20 where the columnar members 61 are not attached. Further, a communication hole 63 is provided in each section of the flat plate of the mold lid 60, and a communication hole 64 is provided in the side periphery of the flat plate. Then, a mold is created by combining the mold container part 20 and the mold lid part 60. FIG. 9 shows an axial cross section of the assembled molds. A cavity 70 having the same shape as the honeycomb porous ceramic to be manufactured is formed inside the mold. In order to achieve a predetermined combination of the mold lid 60 and the mold container 20, they are removably fixed with screws 80 through a communication hole 64 provided in the side assembly of the mold lid 60. The urethane foam raw material liquid is injected into the assembled molds shown in FIG. 9, the inside of which has been previously coated with a shape-retarding agent, through communication holes 63 selected every other time. At this time, the air inside the mold is discharged from the remaining communicating holes 63, thereby improving the injection of the urethane foam.

Next, the urethane foam was foamed in the cavity 70 and cured by heating at 80° C. for 15 to 60 minutes.
Thereafter, the mold waist portion 20 and mold lid portion 60 are removed to obtain a honeycomb structured urethane foam. The urethane foam molded body with a honeycomb structure created by the above method has a thin film called a cell wall between the skeletons forming a three-dimensional network, so this urethane foam molded body is placed in a container and is used to absorb flammable gas and air or oxygen. was introduced and a spark was ignited to burn the cell wall and remove it. Next, the molded body was immersed in a ceramic slurry made by mixing and stirring powder containing MgO, Al ₂ O ₃ , and AiO ₂ , which becomes a cordierite composition by combustion, water, and polyvinyl alcohol, and after removing excess slurry. , and then heated and dried at 100 to 120°C, and this immersion and drying process was repeated several times.

On the other hand, two cylindrical urethane foams with cell walls removed are prepared, and the two urethane foams are immersed in the same ceramic slurry as described for the honeycomb member 4 above. After removing excess slurry, it was heated and dried at 100 to 120°C, and this immersion and drying process was repeated several times. Also, for example, Cr21-23%,
A spirally wound heater wire made of 5.3 to 5.7% Al and the balance Fe is prepared, and this heater wire is sandwiched between the urethane foams to which the slurry is adhered.

Next, the slurry-impregnated urethane foam with the heater wire sandwiched therebetween was pressed against the slurry-impregnated honeycomb structure urethane foam and fired at 1300 to 1470°C for 2 to 6 hours.

Thereby, as shown in FIG. 2, the filter members 4 and 10 have an integral structure. Of course, the filter parts 101 and 102 of the filter member 10 also have an integral structure with the heater wire 5a sandwiched between them. The porous ceramics constituting these filter members 4, 10 have a three-dimensional mesh-like skeleton as shown in FIG. Note that the honeycomb filter member 4
In this case, when the urethane material is foamed, the material comes into pressure contact with the inner surfaces of the container section 20 and the lid section 60, causing the foam to collapse or become extremely fine, so that the closing section 4c is sufficiently clogged. becomes.

Next, the operation of the apparatus of the present invention will be explained using FIG. The exhaust gas discharged from the diesel engine (see Fig. 1) is filtered through the filter section 1 of the filter member 10.
Pass through 01,102. In other words, the exhaust gas passes through the space (see FIG. 4) formed between the three-dimensional mesh frameworks of the porous ceramics that constitute both filter sections 101 and 102.

The exhaust gas that has passed through this filter member 10 is then transferred to a large number of passages 4a of the honeycomb filter member 4.
The liquid enters the air passageway 4b and flows out into another adjacent passage 4a via the partition wall 4b. The partition wall 4b has the structure shown in FIG. 4, and the exhaust gas passes through the filter sections 101 and 102.
Similarly, it passes through the space between the three-dimensional mesh skeletons.

The carbon particles in the exhaust gas collide with the three-dimensional mesh skeleton of the porous ceramic of the filter members 4 and 10 and are captured on the skeleton.

As shown in FIG. 6, the density of the carbon particles collected inside the filter member 10 becomes maximum. Since the electric heater 5 is arranged at the position where this density is maximum, when the electric heater 5 is energized during regeneration, the area with the highest density of carbon particles will first ignite and burn, and this will be used as a spark. The carbon particles collected on the downstream side are burned. Therefore, the collected carbon particles can be efficiently burned out and removed.

Further, in the partition walls 4b of the honeycomb filter member 4, the spaces formed between the three-dimensional network skeletons serve as through holes as described above, so that the ventilation resistance is small and the pressure loss can be reduced. By the way, when comparing the conventional honeycomb structured filter member and the honeycomb filter member of the above example, the conventional example has a carbon particulate collection efficiency of 90 to 100 mmHg.
While the pressure loss in the above example is 45~
The pressure loss is only 50mmHg and 1/2.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications as described below are possible.

(1) As shown in FIG. 10, the filter member 10 may have a single layer structure.

(2) Honeycomb filter member 4 and filter member 10
Of course, the two may be manufactured independently in advance, and then both may be bonded with a ceramic adhesive and fired.

(3) The filter member 10 may have a general honeycomb structure.

(4) The material of the electric heater 5 is SiC, MoSi ₂ , TiC−
Al ₂ O ₃ system, TiC-TiN-Al ₂ O ₃ system, TiN-Al ₂ O ₃
Ceramic materials such as ceramics may also be used. Also,
Electric heaters made of metal materials other than those used in the above embodiments may also be used.

(5) The material of each filter member 4, 10 is not limited to cordierite, and various ceramic materials can be used.

The filter member and the pre-filter member can be structurally integrated with each other due to their ceramic materials, making it possible to avoid separation between them due to thermal expansion, and ensuring that the heat generated by the heater wire of the pre-filter member is absorbed. Since the particles can be transmitted to the filter member side, the collected particulates can be burnt efficiently.

Since the heater wire is reliably held inside the prefilter member, the heater wire does not move inside the prefilter member, and breakage of the heater wire can be suppressed.

Since the heater wire can be held in the prefilter member at the same time in the process of integrating the filter member and the prefilter member, there is no need to arrange the heater wire inside the prefilter member in a subsequent process, which simplifies the manufacturing process. can be achieved.

[Brief explanation of drawings]

Fig. 1 is a partially broken sectional view showing the mounting position of the particle collection device of the present invention, Fig. 2 is a sectional view showing an embodiment of the device of the present invention, and Fig. 3 is the terminal structure of the electric heater of Fig. 2. FIG. 4 is a perspective view showing the organization of the filter members 4 and 10 in FIG. 2, FIG. 5 is a perspective view showing the honeycomb filter member 4 in FIG. Characteristic diagrams of FIGS. 7a and 7b and FIGS. 8a and 8b, used to explain the operation in the embodiment, show the mold used for manufacturing the honeycomb filter member 4 shown in FIG. Figure b is each figure
9 is a sectional view showing a combination of the molds shown in FIGS. 7 and 8, and FIG. 10 is a sectional view showing another embodiment of the present invention. 4... honeycomb filter member, 4a... passage,
4b...Partition wall, 4c...Closing portion, 5...Electric heater, 10...Filter member.

Claims (1)

[Claims] 1. A step of impregnating a ceramic slurry into a porous organic material molded body having a honeycomb shape that is burnt out by combustion; a step of impregnating a ceramic slurry into two cylindrical shaped porous organic material molded bodies that are burnt out by combustion; sandwiching an electric heater wire between the two cylindrical porous organic material molded bodies impregnated with a ceramic slurry having the same composition as the ceramic slurry; a step of firing the molded body with the electric heater wire sandwiched between the ends thereof in pressure contact, and the firing step incorporates the heater wire inside the end surface of the porous ceramic honeycomb filter member. 1. A method for manufacturing a ceramic member for collecting particulates in an internal combustion engine, characterized by integrating a porous ceramic prefilter member.