JPH034725B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a filter device for removing combustible particulates contained in gas, particularly combustible particulates such as carbon contained in automobile exhaust gas. More specifically, the present invention relates to a filter device that efficiently burns and removes filtered combustible particulates while maintaining high filterability by energizing a part of the filter device to generate heat.

[Conventional technology] Conventionally, for example, as a pollution control measure, automobile engines,
In particular, it has been proposed to use a filter in the exhaust system or exhaust recirculation system to remove carbon particulates contained in the exhaust gas of diesel engines, but when used for a long time, carbon accumulates and causes clogging. It had the disadvantage of causing pressure loss.

To solve this problem, as shown in FIG.
A combustion burner 3 is placed in the burner 3, and the fuel in the burner 3 is ignited at regular intervals using an ignition heater 4 such as a glow plug to heat the filter 2 and
As shown in FIGS. 3 and 3, an ignition sheathed heater 6 is attached to the end face of the filter 5 in the exhaust gas inflow direction F, and the filter 5 is heated by electricity supplied from the outside through the connector 6a, and the combustible particulates are heated. A method was used to prevent clogging by incinerating the waste.

[Problems to be solved by the invention] However, in all of the above methods, not only the structure of the device is complicated and the cost is high, but also when a burner is used, the exhaust pipe itself is exposed to high temperature, and the exhaust pipe This caused problems in the durability of the exhaust pipe, and also caused adverse thermal effects on equipment around the exhaust pipe. In addition, when heating directly with a sheathed heater for ignition, in addition to the above-mentioned problems with the burner, the amount of heat leaking out of the filter is greater than the amount of heat consumed by the combustible particles, so the power used by the heater increases. However, the battery installed in the car was extremely worn out, making it impractical.

To solve this problem, it is conceivable to reduce the diameter of the heating element and place it in close contact with the center of the end face of the filter on the exhaust gas inflow side, or to embed it inside the filter near the end face. However, even in this case, the carbon adheres almost uniformly to the entire front surface and interior of the filter, so when the carbon is burned, the combustion heat reaches the exhaust pipe directly, and the effect on the exhaust pipe cannot be ignored.

Therefore, in view of the above-mentioned shortcomings of the conventional technology, the inventor of the present invention has conducted extensive research and determined that by unevenly distributing carbon adhesion caused by the filter to the center of the filter, the present inventors can reduce the thermal adverse effect on the conventional exhaust system or exhaust gas recirculation system. The present invention was completed based on the discovery that combustible particulates can be efficiently removed with as little energy as possible.

[Structure of the Invention] That is, the gist of the present invention is to provide a filter device for removing and incinerating combustible particulates in exhaust gas, in which the end face of the filter on the exhaust gas inflow side is directed toward the inside of the filter and is aligned with the central axis of the filter. A combustible material comprising a tapered surface that converges in the direction of the filter, and a gas-permeable electrically-heating plate-shaped member having a diameter smaller than the filter diameter is attached to the innermost part of the end surface without contacting the outer circumferential surface of the filter. It is located in a filter device for removing harmful particles.

[Example] Next, embodiments of the present invention will be described based on the drawings.

FIGS. 4 and 5 show a front view and a sectional view thereof of an embodiment of the present invention. Here, 11 is a filter device for removing combustible particulates of this embodiment, 12 is a filter, 13a and 13b are lead wires, and 14 is a gas-permeable electrical heating plate. The end surface 16 of the filter 12 on the exhaust gas inflow side forms a tapered surface that converges toward the inside of the filter 12 and toward the central axis of the filter 12, a conical surface in this example. The heat generating plate 14 is fitted into the groove 17, and lead wires 13a and 13b led out from the heat generating plate 14 are disposed.

Among these constituent parts, the filter 12 is constructed in the shape shown in the front view in FIG. 6 and the right side view in FIG. The end face 16, which is the outer surface of the wall body 18, is opened in a checkered pattern. The outlet 22a of the outlet passage group 22 is similarly opened at an end surface 23 opposite to this end surface 16, that is, on the outer surface of the wall 19, and the filter 12 as a whole together with its cylindrical peripheral surface 20 is viewed in perspective in FIG. It forms a cylindrical body as shown in the figure. However, in Fig. 9, the inlet 21a
has been omitted.

The inlet passage group 21 is closed by a closing wall 21b, which also serves as the wall body 19, at the end of the passage opposite to the inlet 21a into which the gas flows, and its side surfaces are composed of four sides of porous ceramic filter walls 24, As a whole, it forms a non-through hole with a square cross section.

The outlet passage group 22 includes an outlet 22 through which gas flows out.
The wall body 18 is closed by a closing wall 22b that also serves as the end of the passage on the opposite side of a, and the side surface thereof is covered with a porous ceramic filtering wall 24 similar to the above-mentioned inlet passage 21.
It consists of four sides, and as a whole forms a hole with a square cross section that is not penetrating.

Each passage of the inlet passage group 21 and the outlet passage group 2
The passages 21 and 22 are arranged adjacent to each other, sharing one or more filter walls 24, and when the passages 21 and 22 have a square cross section, a maximum of 4 filters per passage.
The side surfaces serve as a common filtering wall between the inlet passage and the outlet passage, and the overall arrangement forms a honeycomb of quadrangular columnar passages, as shown in the cross-sectional view of Fig. 8, and as described above, both ends of the The surfaces 16 and 23 have a square inlet 21a or outlet 22a and a closing wall 22b or 21b forming a checkered pattern.

The wall 25 also includes the entire filter and forms a cylindrical side surface 20.

Among the walls 18 and 19 forming both end surfaces 16 and 23 of the filter 12, the wall 18 on the exhaust gas inflow side
The inside is formed in the shape of a truncated cone, so-called a mortar shape, and the storage recess 15 and the groove 17 are provided on the same plane as the bottom surface of the storage recess 15 on the inner bottom surface, so that the other wall 19 It is thicker than that.

Next, the first example of the gas permeable electrical heating plate member 14 is constructed in the shape shown in the front view in FIG. 10 and the right side view in FIG. disc-shaped sintered body of ceramic,
Reference numeral 28 indicates a large number of gas permeation holes drilled throughout the disk-shaped sintered body 27, and 29 indicates a current-carrying heating wire of a high-melting point metal buried inside the disk-shaped sintered body 27. The high melting point metal current-carrying heating wire 29 is formed by hot-pressing a linear body of metal such as tungsten, molybdenum, or an alloy thereof between two ceramic discs having through-holes 28, or by hot-press molding the wires of metal such as tungsten, molybdenum, or their alloys. Print metal in a line on one sheet, and print on the other sheet.
It is formed inside the ceramic disc-shaped sintered body 27 by sandwiching it between two disc-shaped ceramics and sintering it. In addition, a small piece 30 of a high-melting point metal plate, such as tungsten, molybdenum, or an alloy thereof, having a coefficient of thermal expansion almost the same as that of the ceramic is preliminarily attached to the disc-shaped ceramic before sintering as a lead wire extraction part.
Two pieces a and 30b are buried near both ends, and both ends of the high melting point metal print or linear body are electrically connected to the small pieces 30a and 30b, respectively. A plate-shaped body 14 is formed by stacking one ceramic sheet on top of this and sintering it. Lead wires 13a and 13b for connection to a power source are connected to the small pieces 30a and 30b exposed on the back surface of the plate-shaped body 14 by brazing with a high melting point brazing material such as nickel wax.

The gas-permeable electrical heating plate-like body 14 formed in this manner is fitted into the housing recess 15 of the filter 12 and is integrated with the filter 12 by adhering with ceramic paste or the like, thereby removing combustible particulates in this embodiment. A filter device 11 is constructed.

The gas-permeable electrical heating plate 14 has a smaller diameter than the filter 12, and the storage recess 15 in which the gas-permeable electrical heating plate 14 is located is located in the center of the filter 12, so that gas permeation is prevented. The electrically conductive heating plate-like body 14 is not in contact with the outer peripheral surface of the filter 12.

When this filter device 11 is applied to the exhaust pipe of an automobile, the exhaust gas that first flows in from the direction of the end face 16 will be stopped before entering the filter 12 because the end face 16 forms the tapered surface as described above. There is a tendency toward the innermost part of the tapered surface, that is, toward the heating plate-like body 14. Next, it enters the inlet passage group 21 through each inlet 21a opened in the end face 16 or the inlet 21a and the transmission hole 28 of the heat generating plate member 14,
The water then passes through the pores of the porous filter wall 24 as indicated by the dotted arrows in FIG. 5, and leaks into the adjacent outlet passage group 22. At that time, particulates in the gas are captured by the filter wall 24, and only the gas flows out through the outlet passage group 22 and from each outlet 22a. If this state continues, the tapered end surface 16, the surface of the filter wall 24 on the inlet passage 21 side, or the filter wall 2
4. Combustible particles such as carbon are deposited inside.
In particular, the distribution of the deposits on the filter 1 is affected by the above-mentioned influence on the exhaust gas flow by the tapered end surface 16.
It shows a tendency to be unevenly distributed near the central axis of 2. In particular, in the tapered end surface 16, the heating plate-like body 14 located at the innermost part
It shows a tendency to be unevenly distributed in the vicinity. Combustible particles also accumulate on the periphery of the end surface 16, but the tapered end surface 16
Since exhaust gas tends to flow along the direction of the heat generating plate 14 and the tapered end surface 16 on which the deposit is placed is inclined toward the heat generating plate 14, the deposit tends to move in the direction of the heat generating plate 14. The force is exerted by the wind pressure of the exhaust gas. Therefore, the fine particles on the tapered end surface 16 tend to move and collect near the heat generating plate 14 during and after deposition.

In this way, if the accumulation becomes significant over a long period of time, it becomes difficult for the exhaust gas to pass through the filter wall 24. Therefore, if left as is, the pressure loss in the filter device 11 will increase, leading to increased fuel consumption in the automobile. When a current is passed between the lead wires 13a and 13b connected to the heat generating plate 14 of the filter device 11 before the pressure loss becomes too large to ignore, the heat generating plate 14 becomes high temperature, and the heat generating plate 14 becomes hot. 1
The combustible particulates that are deposited in large numbers near 4 are easily heated above the ignition temperature and are burned first. Then, combustion occurs inside the filter 12. When the combustible particulates burn and disappear in this manner, the function of the filter 12 is restored, making it possible to prevent pressure loss.

During this time, the exhaust gas flows through the through holes 2 of the heat generating plate body 14.
It is heated to a high temperature while passing through filter 8, and then releases the amount of heat received while passing through filter 12. Since the heat-generating plate-like body 14 is located at the innermost part of the end face 16, it can heat the entire filter 12, especially the vicinity of the central axis, and helps the continuous combustion of combustible particulates ignited on the upstream side within the filter 12.

As described above, since the end face 16 has a tapered conical shape, combustible particles tend to accumulate on the central axis portion of the filter 12. Since the heat-generating plate 14 is buried in the center axis of the filter 12, the heat generated by the heat-generating plate 14 is effectively applied to the combustible particles that have accumulated in the vicinity of the center axis of the filter 12. Therefore, ignition is possible earlier than when combustible particles are uniformly deposited over the entire filter, and continuous combustion is possible. Furthermore, since the heating and combustion are concentrated toward the central axis, there is little adverse effect of heat on the outside, such as the exhaust pipe.
In addition, it is energy-saving, with power consumption being 1/2 to 1/3 compared to the sheathed heater system for ignition, and the heater has a long lifespan because the heating wire uses tungsten or molybdenum, a metal with a high melting point. The heat-generating materials used in sheathed heaters for ignition are generally Fe-Cr and Ni.
-It is a Cr or Ni wire and has a melting point less than half that of tungsten or molybdenum, so it is easily broken due to overvoltage or overcurrent.

Application to an automobile exhaust pipe is, for example, as shown in FIG. 12. Here, the filter device 31 for removing combustible particles is housed in an insulating housing tube 37 and inserted and fixed into an exhaust pipe 38. Take-out portion 33 of the heat generating plate-like body 33 provided on the end face of the exhaust gas inflow side F
The lead wire 36a led out from the filter 3
Passing through the groove 31a on the end face of No. 2, and further through the groove 31a
The lead wire 36a passes through the through hole of the insulating storage cylinder 37 from the end thereof, and then leads out to the outside of the exhaust pipe 38 via an insulator 39a provided through the exhaust pipe 38, and is grounded.

On the other hand, the lead wire 36b led out from the take-out portion 33b passes through the groove 31b on the end face of the filter 32, and then passes through the axial groove provided on the inner peripheral surface of the insulating housing cylinder 37 from that end. It passes through a through hole in the flange 37b of the insulating housing cylinder 37 at the rear of the filter device 31 and is led out to the rear of the filter device 31. Next, the lead wire 36b is connected to the exhaust pipe 3 through an insulator 39b provided through the exhaust pipe 38.
8 and connected to one terminal of the switch 40. The other terminal of the switch 40 is connected to the positive side of the power battery E, and the negative side of the power battery E is grounded. The positive lead wire 36b is connected to the filter device 3
1. The reason why it is led out to the rear is to prevent a short circuit with the ground side due to carbon accumulation that tends to occur in the front.

When exhaust gas flows into the filter device 31 from the upstream direction F in this state, the exhaust gas first flows into the inlet passage 34 as described above, and then passes through the filter wall 32a as indicated by the dotted line arrow to the outlet passage 35 side. and is discharged from the rear outlet of the filter 32. If this state is repeated, combustible particles in the exhaust gas will be unevenly distributed and captured near the central axis of the filter 32 due to the effect of the tapered end surface as described above. If the switch 40 is turned on and electricity is applied to the heat-generating plate-like body 33 when a certain amount of accumulation has occurred, the heat-generating wire buried inside the heat-generating plate-like body 33 is heated, and the entire heat-generating plate-like body 33 becomes high temperature, and the heat generating plate-like body 33 as a whole becomes hot. By burning the combustible particles and further heating the exhaust gas that passes through the heat-generating plate 33, the filter 32 located downstream of the exhaust gas, especially near its central axis, is heated, and the combustible particles are unevenly distributed there. The accumulated combustible particles such as carbon ignite and burn and disappear. In this way, most of the combustible particles are burned near the central axis of the filter 32 and removed at an early stage. As a result, even if the filter device 31 is left in use, combustion can be regenerated without adversely affecting the exhaust pipe 38, pressure loss can be kept small, and high filtration performance can be achieved. In addition, even before combustion, there are fewer combustible particles in the periphery than in the central shaft, so even if they accumulate enough to burn in the central shaft, the periphery still has sufficient filtration ability, so in the unlikely event that combustion treatment is not carried out, Pressure loss can be kept low even when left unused.

The heating plate member 33 may be energized, for example, at fixed time intervals when the engine is operating, or may be carried out by calculating the pressure loss of the engine using various sensors and energizing it when the pressure loss exceeds a certain value.

In addition to the honeycomb type filter used in the embodiments, the filter used in the present invention has a spongy porous structure, or an aggregate structure of many cotton-like materials such as a felt-like structure or a woven fabric-like structure. Filters such as can be used.

In addition to the first example in which a heater is embedded in a gas-permeable non-conductive ceramic as used in the example, the heat-generating plate-like body includes the front view shown in FIG.
It is also possible to use a gas-permeable electricity-generating plate-like body 45 in the form of a conductive ceramic with gas permeation holes as shown in the second example shown in the right side view of FIG. Here, 46 is a disk made of conductive ceramic such as silicon carbide, and metallized layers 48a,
48b is provided, and the metallized layers 48a, 48
Lead wires 5 are connected to b with solders 49a and 49b, respectively.
0a and 50b are connected. A large number of crescent-shaped gas permeation holes 47 are bored in the center of the disk 46, and the shape as a whole is such that a curved or straight rod-shaped conductive ceramic with a square cross section is stretched between both ends. . A filter device to which this heating plate-like body 45 is applied has both lead wires 50a, 50.
By passing current between the terminals b, the rod-shaped conductive ceramic 46a generates heat, and the combustible particles can be burned and extinguished in the same way. The heating plate-like body 45 may have either the surface 51 on the side of the metallized layers 48a and 48b or its back surface 52 as the filter side.
If the bottom surface of the storage recess is flat, it is preferable to have the surface 52 on the filter side, since the close contact with the filter is perfect and the thermal conductivity is improved, so that it is preferable in terms of heating efficiency near the center axis of the filter. This also applies to the heat generating plate-like body 14 of the first example, and it is preferable for the same reason that the surface without the take-out portion be the filter side.

[Effects of the Invention] As detailed above, the filter device for removing combustible particulates of the present invention has a tapered surface whose end face converges toward the inside of the filter and toward the center axis of the filter, thereby improving gas permeability. Since the current-carrying heat-generating plate is attached to the innermost part of the tapered end surface, there is no need for a special structure for the exhaust pipe or recirculation pipe, and most of the heat generated is transferred from the end surface of the filter to the filter. Move inside. In particular, heat generated by energization is generated deep inside the filter, and since combustible particles are concentrated on the central axis side, heat generation due to combustion is also generated on the central axis side of the filter, making it easy to ignite and continue combustion. ,
Moreover, the adverse thermal effect on the exhaust pipe, the reflux pipe, or the surrounding area is extremely small. Moreover, since the combustible particles are concentrated and unevenly distributed near the center axis of the filter, the accumulated combustible particles can be burned and extinguished with little energy, and the filter device can always be maintained with low pressure loss and high filterability.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional example using a burner, Fig. 2 is an explanatory diagram of a conventional example using a sheathed heater for ignition, Fig. 3 is a front view thereof, and Fig. 4 is a first embodiment of the present invention. 5 is a front view of the filter, FIG. 6 is a front view of the filter section, FIG. 7 is a right side view of the filter, FIG. 8 is a sectional view of the filter, FIG. 9 is a perspective view of the filter, and FIG. Fig. 10 is a front view of the first example of the gas-permeable electrical heating plate, Fig. 11 is a right side view thereof, and Fig. 12 is a case in which the filter device for removing combustible particulates of the present invention is applied to an automobile exhaust pipe. FIG. 13 is an explanatory diagram of the second gas-permeable electrically heating plate-like body.
A front view of the example, and FIG. 14 shows a right side view thereof. 11... Filter device for removing combustible particulates, 1
2, 32...Filter, 13a, 13b, 36
a, 36b, 50a, 50b...Lead wire, 1
4, 33, 45...Gas permeable electrical heating plate-like body,
15... Storage recess, 16... Tapered end surface on exhaust gas inflow side, 21, 34... Inlet passage group, 22, 3
5... Outlet passage group, 24, 32a... Filtering wall.

Claims (1)

[Claims] 1. In a filter device for removing and incinerating combustible particulates in exhaust gas, the end face of the filter on the exhaust gas inflow side has a tapered surface that converges toward the inside of the filter and toward the center axis of the filter. 1. A filter device for removing combustible particulates, characterized in that a gas-permeable electrically conductive heating plate-like member having a diameter smaller than the filter diameter is attached to the innermost part of the end face without contacting the outer peripheral surface of the filter. 2. The filter forms a wall structure that forms a plurality of passages extending from the exhaust gas inlet side to the outlet side, and the passages include an inlet passage group whose outlet side is closed by an outlet closing wall, and an inlet side which is closed by an inlet closing wall. Claim 1, wherein the filter comprises a group of outlet passages, and any one inlet passage is a honeycomb type filter that shares a wall with at least one outlet passage, and the wall forms a filtering wall for trapping combustible particulates. A filter device for removing combustible particulates. 3. A method for removing combustible particulates according to claim 1 or 2, wherein the gas-permeable electrically heating plate-like body is made of non-conductive ceramic with a heater attached and gas permeable holes formed therein. filter device. 4. The filter device for removing combustible particulates according to claim 1 or 2, wherein the gas-permeable electrically heating plate-like body is made of conductive ceramic with gas permeable holes.