JPH03217617A - Honeycomb filter device - Google Patents

Abstract

PURPOSE:To effectively conduct heat of resistance heating elements to the partition wall of a filter by embedding many heating resistors in the sealing parts of a honeycomb filter. CONSTITUTION:In a honeycomb filter 1, the opening parts of many through holes 1a in a honeycomb structure are sealed with blockading parts 1c. On the end face side of the filter 1, an electrode 4 arranged in the crossing direction against the direction in which the blockading parts 1c are continuously arranged not through the opening parts and electrodes 5 arranged on the outer circumferential side of the filter 1 are provided. Many heating resistors 3 are embedded in the sealing parts 1c in the direction in which the parts 1c are continuously arranged, and bridged and connected between both electrodes 4, 5. Hereby, heat of the heating resistors 3 can be effectively conducted to partition walls 1b, uniform heat generation can be performed, and hence regeneration of the filter 1 can be effectively performed with low voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a honeycomb filter device used for collecting and purifying particulates in exhaust gas emitted from diesel vehicles, for example.

[Prior art] Conventionally, as this type of honeycomb filter device, the Japanese Patent Publication No. 1
There is one described in Publication No.-22449.

This is a case that houses a Ceraminoku foam filter.
It has a structure in which an electrode is arranged to cross over the end surface of the filter, another electrode is arranged outside the case, and the two electrodes are bridged and connected by a large number of heating resistors. ing.

Then, the exhaust gas is passed through the filter, and particulates such as carbon in the exhaust gas are captured by the filter, and when regenerating the filter, the heat generating resistor is energized,
The particulates caught in the filter are combusted.

However, in the conventional type, the heating resistor is easily broken due to vibrations, etc., and therefore, the durability is poor.

In order to solve this difficulty,
As described in the above publication, a configuration has been proposed in which a heating resistor is embedded in a sealing part that seals the opening of a through hole on an end face of a honeycomb filter.

Specifically describing this configuration, in order to seal the heating resistor within the sealing part that seals the opening of the through hole, the heating resistor is inserted while partially blocking the unsealed opening. The heating resistor is placed over the end face and embedded within the sealing part.

[Problem to be solved by the invention]

However, the above-mentioned conventional device (Japanese Utility Model Publication No. 61-40893) has the following unsolved problems.

(a) Since the heating resistor partially blocks the opening, it acts as a resistance to the exhaust gas against the nicum filter.

(b) The heating resistor that partially blocks the opening, that is, the heating resistor exposed in the opening, effectively transfers heat to the partition wall that isolates the through holes of the honeycomb filter. The filter cannot be regenerated, and high voltage is required to fully regenerate the filter.

(C) No special consideration is given to the placement of the heating resistor, and as a result, differences in the length of the heating resistor tend to occur, resulting in parts where the resistance value of the heating resistor differs locally. , uniform heat generation may not be achieved, leading to poor reproduction, and local concentration of current may occur, leading to disconnection of the heating resistor.

The present invention has been devised in view of the above points, and its purpose is to effectively transfer the heat of the heating resistor to the partition wall that isolates the through holes of the honeycomb finoreta, Moreover, it is an object of the present invention to provide a honeycomb filter device that can achieve such effects with a low voltage, can generate uniform heat from a heating resistor, and can prevent disconnection of the heating resistor.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a honeycomb filter in which every other opening of a large number of through holes of a honeycomb structure is sealed with a sealing part, and the honeycomb filter. an electrode arranged on the end face side of the filter in a direction crossing the direction in which the sealing parts are arranged continuously without intervening the openings; and an electrode arranged on the outer peripheral side of the honeycomb filter;
The sealing part is provided with a large number of heat generating resistors embedded in the sealing part in the direction in which the sealing part is continuously arranged and bridged and connected between the two electrodes. be.

Further, the resistance values of a large number of heating resistors may be set to be the same.

Further, thermal stress relaxation means may be provided on the electrodes arranged on the end face side of the honeycomb filter.

Furthermore, both cough electrodes may be directly fixed to the honeycomb filter by providing pins on both electrodes and fixing the pins to the through holes of the honeycomb filter.

Further, a temperature sensor for detecting the temperature of the heating resistor may be placed in a position close to the part of the heating resistor buried by the sealing part, or both electrodes may be integrated into the end face of the honeycomb filter. You can leave it there.

(Function) A large number of heating resistors are embedded in the sealing part of the honeycomb filter, and the openings are not obstructed, so there is no effect on the resistance of exhaust gas passing through the filter. .

The heat of the heating resistor can be transferred to the partition wall of the filter without being carried away by the exhaust gas passing through the opening, so that regeneration of the filter can be effectively achieved.

Therefore, there is no need to increase the voltage applied to the heating resistor.

Further, both ends of the heating resistor are arranged on the end face side of the filter, and on the outer circumferential side of the filter and electrodes arranged in a direction intersecting the direction in which the sealing parts are arranged continuously without intervening the openings. Moreover, since the heating resistor is a horizontal structure embedded in the sealing part, the arrangement of both electrodes and the buried configuration of the heating resistor combine to create a large number of heating resistors. The length, that is, the resistance value, can be made equal between both electrodes, and therefore uniform heat generation can be achieved for the filter.

Furthermore, since the thermal stress relaxation means provided on the electrode can relieve the thermal stress acting on the electrode, it is possible to prevent the heating resistor connected to the electrode from deforming and to avoid disconnection. .

Furthermore, the pin provided on the electrode allows the electrode to be securely fixed to the filter.

Furthermore, the temperature of the heating resistor can be detected by the temperature sensor, and the temperature of the heating resistor can be controlled based on the result of this detected temperature.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described. 1st
In the first embodiment shown in Figs. to 8, l is a honeycomb filter made of cordierite, and the honeycomb filter 1
has a large number of through holes 1a in the axial direction, and the through holes 1
Every other opening in a is sealed by a sealing part IC. As a result, the exhaust gas 1 that has flowed into the filter 1 through the through hole 1a is transferred to the partition wall 1 that separates the through hole 1a.
C flows through the adjacent through hole la through b, and flows into the partition wall tb.
Particulates in the exhaust gas are captured.

A stainless steel wire 10 is wrapped around the entire periphery of the honeycomb filter 1, and the filter 1 is press-fitted into a stainless steel case 2 via a wire wire.

Further, on one end surface side of the filter 1, a sealing member 11 made of ceramic is press-fitted. The filter member l1 has a property of expanding due to the heat of the exhaust gas passing through the filter 1, and the seal member 11 seals between the filter l and the case 2, so that all of the exhaust gas is sealed. passes through filter 1.

One end side of the filter 1 is an annular seat 17a placed on an arcuate seat 2a formed at one end of the case 2.
are in contact through. On the other hand, the other end side of the filter l is in contact with the end knob 17b arranged on the other end side of the case 2, and the 3fh end knob 17b is held in place by the filter holding member 20 identified on the end side of the case 2. is fixed. Such endocension 17
a# and the end cushion 17b restrict the movement of the filter 1 in the axial direction.

A rod-shaped negative electrode 4 is stretched over one end of the case 2 at a position above the end face of the exhaust gas outlet side of the filter 1 and equally dividing the end face into two in the radial direction. One end of the electrode 4 is directly welded to the case 2, and the other end is connected to a plate 7 fixed to the case 2 by screws to allow the expansion to escape when the electrode 4 thermally expands. is sandwiched between.

On the other hand, on one end side of the case 2, substantially L-shaped positive electrodes 5 are fixed at four locations above the outer peripheral area of the exhaust gas inlet side end surface of the filter 1. In this fixing structure, the electrode 5 is directly screwed into the case 2 with a screw 24 via a pair of insulators 23 made of alumina and a washer 22 made of copper. The electric wire 5 is electrically protected by a metal cover 31 fixed to the case 2.

Further, the electrode 5 is welded to a bolt-shaped external electrode 12, and the external electrode 12 is fixed to the case 2 by sandwiching the case 2 through an alumina insulator 13 and a heat-resistant gasket 14, and tightening a gasket 16. .

The external electrode 12 is connected to the lead wire 15, and the lead wire 1
5 is connected to an electric control circuit section (not shown). The connection between the external electrode l2 and the lead wire 15 is connected to a metal electrode cover 1 fixed to the case 2 with a screw (not shown).
A rubber bushing 28 is interposed between the cover 18 and the lead wire 15.

A large number of heating resistors 3 are arranged on the end face of the filter 1 on the exhaust gas outlet side. The heating resistor 3 is arranged in the same pattern in an area equally divided into four in the diagonal direction of the lattice of the filter l (the partition wall 1b), that is, in the direction in which the sealing parts 1c are continuously arranged without passing through the openings of the through holes 1a. The sealing portions 1c are embedded in every other row of sealing portions 1c. The buried configuration is a rectangular wave shape extending in the axial direction of the filter 1 within the sealing portion lc, and extending at the intersection of the partition walls 1b.

The heating resistors 3 extend in the diagonal direction of the grid, and the heating resistors 3 are arranged in parallel. In addition, each heating resistor 3
are all of the same length so that they have the same resistance value, and therefore the heating resistor at the outer periphery of the filter l has a bent shape.

For reference, the buried depth of the heating resistor 3 is approximately 5 to 1
For example, in the case of a vehicle power supply of 12V, it is preferable to adjust the resistance value to 5[11111] and the resistance value to be about 1.5Ω from the viewpoint of heat generation amount, that is, regeneration efficiency. To obtain this resistance value, IfL')' of the filter 1 is 200 mm, and when the through hole 1a is 100 mm thick, the wire diameter of the heating resistor 3 is 0. 6mm, and the number of buried holes is 26.

By the way, one end of the heating resistor 3 of each of the four-division patterns is welded and connected to one electrode 4, and the other end is welded and connected to each of the four electrodes 5. Note that a metal caper 26 is fixed to the electrode 4 through a screw 27Q so as to cover the connection portion of each heating resistor 3 with the electrode 4.

Two thermocanople stays 9 are stretched on the case 2 adjacent to and parallel to the 71' eggplant electrode 4. A sheath 30a of a thermocouple 30 is supported on the stay 9,
There are four thermocouples 3o corresponding to the four-division pattern of the heat-generating resistor 3, and the sheath 30a of the thermocouple 30 is connected to the filter 1 at the center of the area of the four-division pattern of the heat-generating resistor 3. One of the through-holes 1a is sealed and embedded in the sealed portion.

Each sheath 30a is fixed to the outside of the case 2 via a known fastening fitting 31, and is supported by a stay 32 fixed to the outer periphery of the case 2. In addition, each sheath 3
A compensation conductor 30b is led out from 0a, and the compensation conductor 30
b is connected to an electric control circuit section (not shown).

In the above configuration, the operation of the honeycomb filter device according to the present invention will be explained next.

Exhaust gas from the direction of arrow A in the figure flows into the filter I through the numerous through holes 1a of the filter (1), passes through the partition wall 1b separating the through holes 1a, and flows into the adjacent through hole la. leak. In this process, particulates mainly composed of carbon in the exhaust gas are captured on the surface of the partition wall 1b, and the amount of particulates in the exhaust gas flowing out from the filter 1 is reduced.

By the way, when it reaches the time when the filter I needs to be regenerated due to repeated collection of particles, a reversing device (not shown) is used to supply secondary air from the heating resistor 3 side of the filter 1 as indicated by arrow B. . Further, a voltage is applied between the electrode 4 and the four electrodes 5. As a result, the entire heating resistor 3 in the four-division pattern generates heat, and the particulates collected in the filter 1 are ignited and burned by the heat, and the filter 1 is regenerated.

In addition, in order to selectively energize each of the heating resistors 3 in the four-division pattern, it is sufficient to select the application of voltage to the four electrodes 5.

In order to achieve such regeneration, it is necessary to heat the end face of the filter l to about 800"C or higher.

The heating resistor (*3) has a melting point of about 1000°C to 1300''C, although it varies depending on the type of material, so if the temperature is raised excessively, the heating resistor 3 will melt.

However, in the above embodiment, a thermocouple 3o is buried at a location where the temperature rises the most at approximately the same depth as the heating resistor 3, and the amount of heat generated by the heating resistor 3 is controlled based on the temperature signal detected by the thermocouple 30. This prevents disconnection of the heating resistor 3 due to overheating.

The embedding pattern of the heating resistor 3 is an important element that greatly influences the regeneration efficiency. Incidentally, the sealing part 1c of the filter 1
An experiment was conducted by varying the embedding ratio of heating resistors 3 with respect to the number of heating resistors 3, and as the embedding ratio was increased, the current value per heating resistor 3 when heating the filter 1 to a uniform ignition temperature decreased. The results showed that the For example, with a burial rate of 25%, 8
A, 6A at 50%. , 4A at 100%.

As the amount of current applied to the heating resistor 3 increases, the risk of melting due to overheating increases. Therefore, it is necessary to bury the heating resistor 3 at a burying rate of 50% or more and at a length equal to the sealing portion 1c of the filter 1. Therefore, the embedding pattern becomes complicated at 75% and 100%, so in order to avoid partial overheating at 50% embedding rate, the density of the heating resistors 3 with respect to the end face of the filter l should be equal, and each heating resistor 3 should be A pattern that makes the lengths equal is good.

In this embodiment, by arranging the electrode 4 near the center of the filter 1, the filter 1 having a diameter of about 200 mm to 250 m+n
Even so, the resistance value of the heating resistor 3 can be set to such a value that the filter 1 can be heated to about 800° C. with an applied voltage of 12V.

However, according to this configuration, the electrode 4 disposed near the center of the filter 1 undergoes a cooling/heating cycle (temperature difference of about 800'
C), a very large thermal stress will be applied.

However, according to this embodiment, one end of the electrode 4 is connected to the case 2.
However, since the other end is sandwiched between the foot 7 and the case 2, so-called cantilever support, when the other end of the electrode 4 slides, the natural vibration of the electrode 4 is The above thermal stress can be relieved without reducing the number.

Therefore, it is possible to avoid deformation and disconnection of the heating resistor 3 due to thermal stress.

On the other hand, since the heating resistor 3 is embedded in the sealing part 1c of the filter l, the heating resistor 3 is integrated with the filter 1, and from this point of view as well, the heating abrasive body 3 is disconnected. can be avoided.

Note that the electrode 4 has a U-shaped cross section and a Caché 26
Because it has a structure that combines the following, it is lightweight, has a large moment of inertia, and is designed with C to increase the natural frequency.

Also, due to the existence of the cover 26, the electrode 4 and the heating resistor 3
It moderates the temperature change at the welded part and avoids the effect of thermal stress on the welded part, and also acts as a heat sink to prevent the welded part from overheating when electricity is applied.

9 to 11 show other examples of thermal stress relaxation means for the electrode 4. FIG. This will be explained. In the eighth case, the center of the electrode 4 was bent in the direction of the filter 1 to have a U-shaped cross section. According to this embodiment, the thermal stress applied to the electrode 4 due to the expansion and contraction of the U-shaped cross section can be alleviated.

In Figures 10 and 11, both ends of the electrode 4 are welded and connected to the case 2, and the electrode 4 is divided into two parts at the center, and the pin parts 4a and 4a are slidable in the divided plane. A sliding hole 4b for fitting is formed, and a hole 4c for inserting a screw 27 for fixing the electrode 4 and the cover 26 is an elongated hole so that the sliding operation can be performed. The bending configuration also allows the thermal stress applied to the electrode 4 to be alleviated.

Figures 12 to 15 show a second embodiment of the present invention in which the electrodes 4 and 5 are placed directly on the end face of the filter 1 to make the filter 1 and the electrodes 4 and 5 integral. be.

To explain this, the negative electrode 4 is formed in a ring shape, and pins 33 are provided at two opposing locations on the electrode 4.
is fixed by a stomper ring 34 to prevent it from coming off.

The electrode 4 is fixed to the outer periphery of the filter 1 by inserting the pin 33 into the through hole la of the filter 1 and fixing the through hole 1a portion with a sealant.

10,000, the positive electrode 5 is formed in a prismatic cross section,
Pins 33 are fixed to both ends of the electrode 5 in the same configuration as the electrode 4. The electrode 5 is formed by inserting the pin 33 into the through hole 1a of the filter 10 at a position where the edge of the filter 1 is equally divided into two, and fixing the through hole 1a portion with a sealant. Fixed in the center.

One end of the heating resistor 3 is arranged in an L direction so as to surround the upper surface of the electrode 4.
It is bent into a letter shape and is welded and connected to the upper surface via a metal cover 35. As a result, the electrode 4 is supported between one end of the heating resistor 3 and the end surface of the filter 1. Note that the cover 35 is used to prevent abnormal heating of the heating resistor 3 during welding, and is not necessarily necessary.

The other end of the heating resistor 3 is bent into an L shape so as to surround the upper surface of the electrode 5, and is welded and connected to the upper surface. As a result, the electrode 5 is supported between one end of the heating resistor 3 and the end face of the filter l.

As described above, the filter 1 with the integrated electrodes 4 and 5 is housed in the case 2 as shown in FIG.

That is, the case 2 is of a two-part type, and is composed of a central cylindrical portion 2a and cone portions 2b at both ends thereof. The filter 1 is housed in the cylindrical portion 2a of the case 2 via end cushions 17a, 17b and a wiring member 10, and all of the exhaust gas passes through the filter 1 by a sealing member 11 made of Ceraminok.

The electrode 5 is connected to a bolt-shaped external electrode 12 via a lead wire 15a. In addition, the electrode 5 and the Riet wire 15
a is connected by welding, and the lead wire 15a and the external electrode 12 are connected by welding. The external electrode 12 is fixed to the case 2 by nanometers 16 via an insulator 13 made of alumina and a gasket 14 made of copper. Lead wire 1
5a is protected by a metal cover 36 welded and fixed to the cone portion 2b of the case 2.

The external electrode 12 is welded and connected to a lead wire 15b, and the lead wire 15b is connected to an electric control circuit section Q (not shown). In order to protect the connection between the external electrode I2 and the lead wire 15b, a metal case 8 is welded to the case 2, and the space between the case 18 and the lead wire 15b is sealed with a rubber pusher 28. The electrode 4 directly contacts the inner surface of the case 2 and is electrically connected to the case 2, and is fixed to the case 2 by welding at one location on the case 2.

The tip of the sheath 30a of the thermocouple 30 is inserted into one through hole 1a located approximately in the center of the filter 1, and the insertion portion is sealed with a sealing portion IC.

The thermocouple 30 is drawn out of the case 2 and connected to the electrical control circuit section.

The present invention is not limited to the above embodiments, but can be modified in various ways as follows.

(1) Although the heating resistor 3 is made of nichrome wire, it may be made of other metal such as Kanthal wire, or may be made of conductive ceramic material such as silicon carbide.

(2) The arrangement pattern of the heat generating resistor 3 can be modified in various ways, and the point is that the resistance value should be approximately the same when bridging and connecting the two electrodes 4 and 5, for example, the filter 1
The outer circumferential portion may be straight without being bent. In this case, since the wire is straight, the wire diameter of the second portion may be made smaller than that of the other portions.

(3) At the connection part between the electrode 4 or electrode 5 and the heating resistor 3, as shown in FIGS. 16 to 18, the heating resistor 3
It is also possible to have a bent configuration. As a result, electrodes 4, 5
It is possible to avoid stress being applied to the heat generating resistor 3 when the heat generating resistor 3 thermally expands.

(4) The pin 33 in FIG. 14 may be omitted.

(5) The material of the filter l is not limited to ceramic, and may be made of metal, for example.

(6) In each of the above embodiments, when the particulates in the exhaust gas are captured by the filter 1, the exhaust gas is caused to flow in the direction of the arrow A, and when the filter 1 is regenerated, the secondary air is caused to flow in the direction of the arrow B. However, it is of course possible to flow the secondary air in the same direction as when capturing, for example during regeneration.

(7) The shape of the through-hole 1a of the filter 1 and the arrangement pattern of the sealing portion IC may be as shown in FIGS. 19(a) to 19(d).

(8) The present invention is not limited to capturing particulates in exhaust gas emitted from a vehicle internal combustion engine,
It goes without saying that the present invention can be widely applied to capturing particulates in exhaust gas discharged from various combustion mechanisms.

[Effects of the Invention] As described above, according to the present invention, the heat of the heating resistor can be effectively transferred to the partition wall of the filter, and the heat can be uniformly generated, so that the filter can be effectively regenerated at low voltage. becomes possible.

Furthermore, since concentration of current can be avoided, disconnection of the heating resistor can be avoided.

Furthermore, the temperature of the heating resistor can be controlled, and further disconnection of the heating resistor can be avoided.

Furthermore, since the electrode and the heating resistor can be integrated into the filter, ease of assembly is improved, for example, when housing the filter in a case.

[Brief explanation of drawings]

1 to 8 show a first embodiment of the present invention, in which FIG. 1(a) is a schematic plan view showing an example of the arrangement pattern of the heating resistor with respect to the filter, and FIG. 1(b) is shown in Figure 1 (a
) is an enlarged plan view of a part of the
FIG. 2 is a partially sectional plan view showing the device including the filter, and FIG. 3 is an I-I [[
A sectional view, FIG. 4 is an enlarged sectional view of the main part of FIG. 3,
FIG. 5 is an enlarged cross-sectional view showing the fixing configuration of the positive electrode;
Figure 6 is an enlarged cross-sectional view of the fixing configuration of the negative electrode, Part 7 is an enlarged cross-sectional view of the connecting part between the negative electrode and the heat generating resistor, and Figure 8 is part 1 of Figure 7. 9 and 10 are sectional views showing a modification of the first embodiment of the present invention, FIG. 11 is a sectional view taken along line XI-XI of FIG. 10, and FIGS. This shows the second embodiment of
FIG. 12 is a sectional view showing the overall configuration, FIG. 13 is an enlarged sectional view showing the xn-xn section of FIG. 12, FIG. 14 is a plan view showing the arrangement of electrodes with respect to the filter, and FIG.
16 and 17 are front views schematically showing modifications to the first and second embodiments, and FIG.
The perspective views and FIGS. 19(a) to 19(d) are plan views illustrating other examples of the shape of the through holes of the filter and the arrangement pattern of the sealing portions in the present invention. ■...filter, la...through hole, lc...sealing portion 3...heating resistor, 4, 5...electrode. 7...Plate, 33...Pin.

Claims (6)

[Claims] (1) A honeycomb filter in which every other opening of a large number of through-holes of a honeycomb structure is sealed by a sealing part, and the sealing part is connected to the end face side of the honeycomb filter through the opening part. electrodes arranged in a direction crossing the direction in which the honeycomb filter is continuously arranged; electrodes arranged on the outer peripheral side of the honeycomb filter; and the sealing section in the direction in which the sealing parts are arranged continuously. 1. A honeycomb filter device comprising: a large number of heat generating resistors embedded in the portion and bridged and connected between the two electrodes. (2) The honeycomb filter device according to claim 1, wherein the resistance values of the plurality of heating resistors are set to be the same. (3) The honeycomb filter device according to claim 1 or 2, wherein the electrode arranged on the end face side of the honeycomb filter is provided with thermal stress relaxation means. (4) The first aspect of the present invention is characterized in that both the electrodes are provided with pins, and by fixing the pins to through holes of the honeycomb filter, the two electrodes are directly fixed to the honeycomb filter. The honeycomb filter device according to any one of items 1 to 3. (5) A temperature sensor for detecting the temperature of the heat generating resistor is disposed at a position close to a portion of the heat generating resistor buried by the sealing portion. A honeycomb filter device according to any one of the above. (6) The honeycomb filter device according to any one of claims 1 to 5, wherein both the electrodes are integrated with an end face of the honeycomb filter.