JPS60111014A - Purifying device collecting fine particle - Google Patents

Abstract

PURPOSE:To improve durability of a regenerative heating heater, by providing a heat generating part, which extends in the central part of an exhaust gas passage connecting mutually neighboring two electrifying-electrode parts, and opening parts, which enable exhaust gas to flow, in this heat generating part. CONSTITUTION:A regenerative heating heater is provided in the upstream side of a filter 2 collecting a fine particle in exhaust gas. A plurality of flat plate- shaped ceramic heaters 32a-32f consisting of ceramic conductive material are arranged in a peripheral direcion, having mutually neighboring two electrifying- electrode parts 35a, 35b fixed to the peripheral part of an exhaust gas passage. A heat generating part 36, which extends to the central part of the exhaust gas passage connecting these electrifying-electrode parts 35a, 35b, is provided, and this heat generating part 36 forms opening parts 37 enabling the exhaust gas to flow.

Description

[Detailed Description of the Invention] CIF, Ming technical field) A method for collecting fine particles, especially carbon-based fine particles, contained in the exhaust gas of a simple engine. The present invention relates to a particulate collection and purification device for purifying exhaust gas.

[Technical Background of the Invention]' Exhaust gas from internal combustion engines such as diesel engines contains fine particles mainly composed of carbon, and in order to purify this exhaust gas, it is necessary to eliminate the fine particles from the exhaust gas. No. In order to collect and purify these fine particles, a filter made of a ceramic honeycomb structure or a ceramic foam structure is used in the exhaust gas system.

However, when such a filter is installed in an exhaust gas system to allow exhaust gas to pass through, the particulates collected by the filter increase the resistance of the exhaust passage, resulting in a reduction in engine output. In order to prevent the resistance of the exhaust passage from decreasing, an electric heater is disposed upstream of the filter to purify the particles by heating and burning them using electric heat. The electric heater described above is called a regenerative heater because it regenerates and purifies the filter.

A conventional regenerative heater is composed of a plurality of rod-shaped metal heaters, and each of these rod-shaped metal heaters is arranged horizontally in an exhaust passage with a gap between them.

[Problems with background technology]

However, the conventional regenerative heater described above has a both-end support structure in which both ends of the linear or band-shaped metal heater are supported by the peripheral wall of the exhaust passage, so the heater becomes loose due to thermal expansion and contraction. There were problems such as contact with the ground body and short circuit, and heaters touching each other. In addition, metal heaters have poor heat resistance, are easily oxidized, are easily broken, and have poor durability.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its objectives are to provide a heater for regenerative heating with high durability, less loosening and deformation due to thermal expansion and contraction, and to be able to be firmly supported, and to be able to withstand vibrations. The purpose of the present invention is to provide a particulate collection and purification device that has a long service life by preventing loosening caused by such factors.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a regenerative heating heater in which a plurality of flat ceramic heaters made of ceramic conductors are arranged in the circumferential direction in the exhaust gas passage, and each of these ceramic heaters is arranged in the exhaust gas passage. It has two adjacent current-carrying electrode parts fixed to the outer periphery, and a heat-generating part that extends to the center of the exhaust gas passage continuously from these current-carrying electrode parts, and the heat-generating part has an opening through which the exhaust gas can pass. It is characterized by having been established.

〔Effect of the invention〕

According to the present invention, since the heater for regeneration heating is a ceramic heater made of a ceramic conductor, it has strong thermal shock resistance, oxidation resistance, and heat resistance, and has excellent durability. Further, the ceramic heater has a flat plate shape and has adjacent current-carrying electrode parts and a heat generating part continuous to these electrode parts.The adjacent electrode parts are fixed to the outer periphery of the exhaust passage, and the heat generating part is exhausted. Since it was extended toward the center of the passage,
The heater has a cantilevered structure supported by the electrode portion, thus freely allowing thermal expansion and contraction.

Therefore, the heater can be firmly fixed by the electrode section, and the ceramic heater will not undergo thermal deformation or loosening of the fixing section, and there will be no fear of loosening even if vibrations are transmitted, resulting in a long life. By improving seismic resistance in this way, the heater can be placed in contact with the filter, making it possible to immediately transfer the heat from the heater to the filter, efficiently heating the filter, and reducing the It is possible to burn off particulates that have accumulated on the surface.

[Embodiments of the invention]

The details of the present invention will be explained based on an embodiment shown in the drawings.

As shown in the partially cutaway side view of FIG. 1, the particulate collection and purification device mainly includes a case 1, a filter 2, and a heater section 3 provided in contact with the exhaust gas upstream side of the filter 2. do.

The case 1 includes a case body 11 and an exhaust gas introduction pipe 12. The case body 11 is made of stainless steel and has a circular or oval cross section, and has a flange 13 at one end and an exhaust gas discharge part 14 at the other end. The exhaust gas inlet pipe 12 has an exhaust gas inlet 15 at one end and a flange 16 at the other end.

The filter 2 is filled in the case body 11 with a heat insulating buffer material layer 21 interposed therebetween. The filter 2 is made of cordierite porous foam ceramic.

As shown in FIG. 2, the heater section 3 includes a heater case 31
and a plurality of, for example six, heater elements 328~
It consists of 32f.

Each heater case 31 is made up of a ring-shaped upper case 33 and a lower case 34 that abut against each other, and each of the heater elements 328 to 32f has an electrode portion, which will be described later, sandwiched between the upper case 33 and the lower case 34. It is fixed with a bolt (not shown).

Each of the heater elements 328 to 32f is arranged in a section where the upstream end face of the filter 2 is equally divided into fan shapes, and each of these heater elements 32a to 32f has a V-shaped planar path, one of which is shown in FIG. has been completed. This heater element has current-carrying electrode portions 35a and 35b at both ends, and a V
The character-shaped portion serves as a heat generating portion 36. A plurality of, for example, triangular openings 37 are formed in the heat generating portion 36, through which exhaust gas can pass.

The heater elements 32a to 32f are made of T i N powder 3
A slurry containing 0txm% and 1% by weight of S i 3N4 70% dispersed in an organic binder consisting of polyvinyl butyral, dibutyl phthalate, and ethanol was formed into a plate shape by a doctor blade method, and then cut into a predetermined shape by a punching method. It is obtained by heating and firing for about 2 hours at a temperature of about 17,507: in an inert gas atmosphere such as nitrogen gas.

Each electrode part 35a of heater niremen h 32a to 32f
, 35b are metalized with a conductive metal such as platinum, metallic nickel, or molybdenum by baking or vapor deposition.

The heater elements 32a to 32f having such a structure are
As described above, each of the electrode parts 35a and 35b is sandwiched between the upper case 33 and the lower case 34 of the heater case 31, and the heat generating part 36 is arranged toward the center of the exhaust passage. Therefore, each of the heater elements 32a to 32f is arranged in the circumferential direction of the exhaust passage, with each heat generating part facing toward the center. In this case, the adjacent heat generating parts 36...
- A gap 11i is formed between them, and a passage through which the exhaust gas can pass is secured by these gaps and the openings 37 formed in the heat generating parts 36... In addition, each heat generating part 36
... are attached so as to uniformly contact the upstream end surface of the filter 2.

One electrode part 35 a of the electrode parts fixed to the heater case 31 is connected to lead wires 38 a to 38 f wired in grooves (not shown) formed in the upper case 33 . It is led out and connected to a connector 39. The connector 39 is connected to a battery (not shown). Note that the other electrode portion 35b is grounded to the body by the heater case 31.

The heater case 31 has a flange 40, which is sandwiched between the flange 13 of the case body 11 and the flange 16 of the exhaust gas introduction pipe 12, and fixed to each other by bolts (not shown).

The particulate collection and purification device of this embodiment having the above configuration is as follows:
It is connected to the exhaust gas system of the internal combustion engine, and exhaust gas is introduced through the exhaust gas inlet 15 of the exhaust gas introduction pipe 12, and particulates in the exhaust gas are collected on the surface of the filter 2. When the pores of the filter 2 become narrowed due to particulates collected on the surface of the filter 2, that is, when the filter 2 becomes worn out, the first lead wire 38a is connected to a power source through the connector 39.

As a result, the power source, the connector 39, the lead wire 38a, one electrode portion 35a of the first heater element 32a, the heat generating portion 36, the other electrode portion 35b1 body ground, the power source,
A closed circuit is formed, and the heat generating portion 36 generates heat due to electrical resistance. The upstream end face of the filter 2 is heated by the heat generated by the heat generating part 36, and the particulates collected in this part start to burn, and this part becomes an ignition point to reduce the particulates attached to the surface of the filter 2 on the downstream side. is burned and removed.

When the ignition of the first heater element 32a is completed in this way, the second heater element 32b is then ignited, and the particulates of the filter 2 that are in contact with the heat generating parts of the heater elements 1 to 32b are burned and removed. Ru. In this way, the heater elements 328 to 32f are sequentially energized to burn the entire filter 2, thereby removing particulates deposited on the surface of the filter 2.

The results of an experiment in which the particulate collection and purification device of this embodiment was installed in the exhaust gas system of a 2000 cc diesel engine will be described. As a comparative example, a conventional metal heater made of nichrome wire was used as a regenerative heater, and the case 1 and filter 2 were the same as those in this example. The results are shown in the table below.

As is clear from the above experimental data, when the ceramic heater of this example is used, the electric power density required for ignition is as low as 36P/ci due to its small heat capacity, compared to that using a conventional metal heater. We were able to reduce power consumption by approximately 50%.

In terms of durability, using the ceramic heater of this example ensures a long life of over 2,000 hours, whereas when using a conventional metal heater, oxidation corrosion progresses and wire breakage occurs, resulting in a lifespan of over 200 hours. It was a lifespan.

Furthermore, the ceramic heater of this example was not damaged by engine vibration or thermal expansion during heating, and exhibited stable durability. This is because each of the heater elements 328 to 32f is cantilever-supported by its electrode portion, so that even if vibration or thermal expansion occurs, the heat generating portion extending toward the center is not restrained.

In this manner, it was demonstrated that the particulate collection and purification device of this example reduces the amount of electric power required for ignition and significantly improves durability.

The arrangement of the plurality of heater elements can be selected depending on the shape of the end face of the filter, and in the case of a circular shape as in the embodiment, one heater element is placed in each fan-shaped segment divided radially from the center of the circle at equal intervals. and also,
In the case of an irregular shape such as an ellipse, two or three types of heater elements of different sizes may be arranged. The shape of the heater element is not limited to a V-shape in plan, but may be, for example, in a U-shape in plan.

Further, the shape of the openings 37 formed in the heat generating portion is not limited to a triangle, but may be circular, square, notched, or the like.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and Fig. 1 is a partially cut-off side view of a particulate collection and purification device, and Fig. 2 is a view taken along the line ■-■ in Fig. 1, showing the structure of a heater for regeneration heating. The arrow view and FIG. 3 are plan views of the heater element. 1...η-7. L)... Filter, 3... Heater section, 32a to 32f... Heater element, 35a,
35b... Electrode part, 36... Heat generating part, 37... Opening part. Applicant's agent Patent attorney Takehiko Suzue Figure 1 [1 Figure 2 Figure 3 311:l

Claims (1)

[Claims] In a particulate collection and purification device that includes a filter that is installed in the exhaust system of an engine and that allows exhaust gas to pass through and collects particulates in the exhaust gas, and a regenerative heating heater that is provided upstream of the filter in the exhaust gas flow. , the regenerative heating heater is composed of a plurality of flat ceramic heaters made of ceramic conductors arranged in the circumferential direction in the exhaust gas passage, and each of these ceramic heaters is connected to a phase plate fixed to the outer periphery of the exhaust gas passage. It has two adjacent current-carrying electrode parts, a heat-generating part that connects to these current-carrying electrode parts and extends to the center of the exhaust gas passage, and an opening through which exhaust gas can pass is formed in the heat-generating part. Particulate collection and purification equipment.