JP2004108332A - Particulate filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable accurate and fine temperature control by providing a particulate filter whose internal temperature can be measured accurately. <P>SOLUTION: The particulate filter 14 has inlet side plugs 8 arranged in positions spaced from the inlet end face of a filter body 7, and has an insertion hole 16 radially formed in the filter body 7 so as to receive the insertion of a temperature sensor 15 in a position immediately before the inlet side plugs 8. The periphery of the filter body 7 downstream of the insertion hole 16 is fitted with a sealing material 11 for airtightly closing a gap against a filter case 10 at least in one place, and the remaining periphery of the filter body 7 is fitted with a cushion material 9 except for the sealing material 11 and the insertion hole 16. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a particulate filter.
[0002]
[Prior art]
Particulate matter (particulate matter) discharged from the diesel engine is mainly composed of soot composed of carbonaceous material and SOF component (Soluble Organic Fraction: soluble organic component) composed of a high-boiling hydrocarbon component. Although it has a composition containing a trace amount of sulfate (mist-like sulfuric acid component), as shown in FIG. 3, an exhaust pipe 3 through which exhaust gas 2 from a diesel engine 1 flows as a measure for reducing this kind of particulates. It is considered that a particulate filter 4 is provided in the middle of the process.
[0003]
As shown in detail in FIG. 4, the particulate filter 4 mainly includes a filter body 7 having a porous honeycomb structure made of a ceramic such as cordierite, and each of the filters in the filter body 7 is divided into a grid. The inlet side of the passage 5 is alternately plugged with plugs 8, and the flow path 5 whose inlet side is not plugged has its outlet side plugged with the plug 8. Only the exhaust gas 2 that has passed through the partitioning porous thin wall 6 is discharged downstream, and particulates are collected on the inner surface of the porous thin wall 6.
[0004]
Since the particulates in the exhaust gas 2 are collected and deposited on the inner surface of the porous thin wall 6, the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging. It is necessary to regenerate the filter 4. However, in the normal operation state of the diesel engine 1, there is little opportunity to obtain a high exhaust temperature enough for the particulates to self-combust. A catalyst regeneration type particulate filter 4 in which an oxidation catalyst formed by adding an appropriate amount of a rare earth element such as cerium to a filter body 7 is being put into practical use.
[0005]
That is, if such a catalyst regeneration type particulate filter 4 is employed, the oxidation reaction of the collected particulates is promoted, the ignition temperature is reduced, and the particulates are burned and removed even at a lower exhaust gas temperature than before. Furthermore, by adding HC (hydrocarbon) to the upstream side of the catalyst, the HC is oxidized on the oxidation catalyst, and the heat of the reaction raises the catalyst bed temperature to actively capture the catalyst. This makes it possible to burn out and remove the collected particulates and to release the retained sulfate.
[0006]
However, when HC or the like in the exhaust gas 2 undergoes an oxidation reaction on the oxidation catalyst, the chance of contact with the oxidation catalyst increases toward the rear portion of the particulate filter 4, so that the oxidation reaction is activated. The temperature distribution in the inside is as shown in the graph of FIG. 6, and the temperature at the front part where the oxidation reaction on the oxidation catalyst does not proceed very hardly rises. If the plugs are alternately plugged, the flow of the exhaust gas 2 stagnates at the front surface of the plug body 8, so that the particulates are liable to adhere. In addition, there is a possibility that the entry end face of the filter body 7 may be clogged.
[0007]
Therefore, in the particulate filter 4 illustrated in FIG. 4, the plug 8 on the inlet side is arranged at a position separated from the entry-side end face of the filter main body 7. Since all the flow paths 5 on the entry side end face of the filter body 7 are opened and no closed face is formed on the entry side end face of the filter body 7, there is no adhesion and deposition of particulates, and the plug 8 on the entry side is Since it is arranged in a high-temperature region (a region exceeding the temperature at which the particulates immediately oxidize: see FIG. 5) penetrating into the back from the entry side end surface of the main body 7, the flow of the exhaust gas 2 at the front surface of the plug 8 on the entrance side. Even if particulates accumulate due to stagnation, the particulates accumulate and are quickly removed under high-temperature conditions without large growth.
[0008]
With respect to the structure in which the inlet plug 8 is separated from the inlet end face of the filter body 7 in this manner, the applicants of the present invention have already filed the following Patent Document 1 as an unpublished prior application. However, as far as the applicant of the present invention knows, there is no known invention which discloses a particulate filter having such a structure.
[0009]
[Patent Document 1]
Japanese Patent Application No. 2002-93980 [0010]
The particulate filter 4 shown in FIG. 4 is housed in a filter case 10 in the middle of the exhaust pipe 3 with its outer peripheral portion held by a cushion member 9. A material 11 is interposed to prevent the exhaust gas 2 from being bypassed.
[0011]
[Problems to be solved by the invention]
However, conventionally, when HC is added to the exhaust gas 2 on the upstream side of the particulate filter 4 to aggressively burn and remove the particulates and desorb the sulfate, etc. Since the control is performed only by the temperature detected by the temperature sensors 12 and 13 disposed on the outlet side, there is a problem that accurate and detailed control cannot be realized.
[0012]
That is, since the filter body 7 of the particulate filter 4 has a large heat mass made of a ceramic such as cordierite, it is difficult to detect only the inlet gas temperature and the outlet gas temperature having poor thermal response. However, the internal temperature of the particulate filter 4 could not be accurately grasped.
[0013]
In fact, according to the knowledge obtained by the present inventor, when the temperature transition before and after the burning of particulates is measured, as shown in the graph of FIG. Under a constant transition condition, the outlet gas temperature changes during the particulate combustion due to the addition of HC by showing a gentle mountain shape as shown by a dashed line B, and the mountain shape of the outlet gas temperature is changed by a particle shape shown by a solid line C. The degree of rise is small compared to the change in the internal temperature of the particulate filter 4 and a time delay occurs. For example, even if the inside of the particulate filter 4 has reached a high temperature state in which the particulate filter 4 may be melted. It is practically impossible to take control immediately by grasping this immediately only from the inlet gas temperature and the outlet gas temperature.
[0014]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a particulate filter capable of accurately measuring an internal temperature, thereby realizing accurate and fine temperature control.
[0015]
[Means for Solving the Problems]
The present invention relates to a filter body made of a porous material integrally supporting an oxidation catalyst and having a large number of honeycomb-shaped flow paths through which exhaust gas flows, and an inlet side and an outlet side of each flow path of the filter body. And a plug body for alternately plugging any one of the above, and the particulate filter in the exhaust gas can be trapped by passing through the porous thin wall partitioning each of the flow paths. In addition, the plug on the inlet side is arranged at a position separated from the inlet side end face of the filter main body, and the temperature sensor is inserted in the radial direction of the filter main body so that the temperature sensor can be inserted and installed immediately before the plug on the inlet side. A hole was formed, and a seal material for hermetically closing a gap between the filter case and the filter case was attached to at least one or more locations on the outer peripheral portion of the filter body behind the insert hole, and the seal material and the insert hole were avoided. Filter book It is characterized in that mounting the cushion material to the remaining outer peripheral portion of the.
[0016]
In this way, it becomes possible to directly detect the internal temperature of the particulate filter by inserting and installing the temperature sensor in the insertion hole, and to perform various controls accurately and based on the internal temperature of the particulate filter. It becomes possible to implement it finely.
[0017]
Here, the insertion hole drilled in the radial direction of the particulate filter spans a plurality of flow paths, but since the drilling position is immediately before the plug on the inlet side, exhaust gas is not generated. Even if it reaches the plug on the inlet side and flows into the adjacent flow path without passing through the porous thin wall through the insertion hole, the plug on the outlet side always hits the plug on the outlet side in the flow path to which it has flowed. Since the gas passes through the thin wall, it is possible to prevent a problem that the exhaust gas passes through the particulate filter without passing through the porous thin wall at all.
[0018]
Also, when the insertion hole is drilled, processing chips remain in each flow path, and all of the processing chips can be easily taken out to the entry side of the filter body without the plug being obstructed in any of the flow paths. It is possible.
[0019]
Furthermore, since the seal member is attached to at least one or more locations on the outer peripheral portion of the filter body behind the insertion hole, the exhaust gas escapes from the insertion hole to the outer peripheral portion of the filter body and bypasses the particulate filter. Troubles are avoided beforehand.
[0020]
In addition, since the cushion member is attached to the remaining outer peripheral portion of the filter body avoiding the sealing material and the insertion hole, the filter body made of a porous material having a brittle strength is reliably protected from running vibration of the vehicle and the like. It is possible not to hinder the insertion of the temperature sensor into the insertion hole.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
1 and 2 show an example of an embodiment of the present invention, and the portions denoted by the same reference numerals as those in FIGS. 3 to 6 represent the same components.
[0023]
As shown in FIGS. 1 and 2, the particulate filter 14 of the present embodiment is configured such that the plug 8 on the inlet side is disposed at a position separated from the inlet side end face of the filter main body 7 in substantially the same manner as in FIG. 4 described above. However, an insertion hole 16 is formed in the filter body 7 in the radial direction so that the temperature sensor 15 can be inserted and installed immediately before the plug 8 on the inlet side.
[0024]
However, it is preferable that the insertion hole 16 is formed after the oxidation catalyst is supported on the filter body 7. If the insertion hole 16 is opened first, the catalyst supporting liquid applied to the filter body 7 Leak out from the insertion hole 16 and it becomes difficult to carry a good catalyst.
[0025]
In addition, seal materials 11 for airtightly closing the gap between the filter case 10 and the filter case 10 are provided at two positions on the outer peripheral portion of the filter body 7 immediately after and behind the insertion hole 16 at a small distance. A cushion member 9 for protecting the filter main body 7 is mounted on the entire outer periphery of the remaining outer peripheral portion of the filter main body 7 avoiding the sealing materials 11 and the insertion holes 16. .
[0026]
Here, for example, a material obtained by knitting a stainless steel wire and processing it into a wavy shape may be used as the cushion material 9, and a silica fiber (alumina fiber or the like may be used) as the seal material 11, for example. What is necessary is just to employ what was made into the shape of felt.
[0027]
In this way, the temperature sensor 15 can be inserted and installed in the insertion hole 16 and the internal temperature of the particulate filter 14 can be directly detected. Various controls can be performed accurately and finely, and the worst situation such as erosion of the particulate filter 14 can be avoided.
[0028]
Here, the insertion hole 16 pierced in the radial direction of the particulate filter 14 spans the plurality of flow paths 5, but since the piercing position is immediately before the plug 8 on the entrance side, Even if the exhaust gas 2 reaches the plug 8 on the inlet side and flows into the adjacent flow path 5 without passing through the porous thin wall 6 through the insertion hole 16, the exhaust gas 2 always exits at the flow path 5 to which the exhaust gas has flowed. As a result, the exhaust gas 2 comes out of the particulate filter 14 without passing through the porous thin wall 6 without fail at all. Can be avoided.
[0029]
Further, when the insertion hole 16 is formed, processing chips remain in each of the flow paths 5, and the processing chips are entirely inserted into the filter body 7 in any of the flow paths 5 without the plug 8 becoming an obstacle. It can be easily taken out to the side, and the processing after the drilling of the insertion hole 16 can be easily completed.
[0030]
Further, since the sealant 11 is attached to at least one or more portions of the outer periphery of the filter body 7 behind the insertion hole 16, the exhaust gas 2 escapes from the insertion hole 16 to the outer periphery of the filter body 7 and the particulate filter It is possible to reliably avoid a problem of bypassing the device 14.
[0031]
Further, since the cushion member 9 is attached to the remaining outer peripheral portion of the filter main body 7 avoiding the sealing material 11 and the insertion hole 16, the filter main body 7 made of a porous material having a brittle strength can be removed from running vibration of the vehicle. It is possible to prevent the temperature sensor 15 from being inserted into the insertion hole 16 while ensuring protection.
[0032]
Note that the particulate filter of the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention.
[0033]
【The invention's effect】
According to the particulate filter of the present invention described above, various excellent effects as described below can be obtained.
[0034]
(I) Since the internal temperature of the particulate filter can be directly detected by inserting and installing a temperature sensor in the insertion hole, various controls can be performed accurately and finely based on the internal temperature of the particulate filter. The worst case, such as erosion of the particulate filter, can be avoided.
[0035]
(II) When directly detecting the internal temperature of the particulate filter by inserting and installing a temperature sensor in the insertion hole, there is a problem that the exhaust gas does not pass through the porous thin wall at all and exits the particulate filter. It is possible to reliably avoid such a problem that the exhaust gas escapes from the hole to the outer peripheral portion of the filter body and bypasses the particulate filter.
[0036]
(III) The processing waste remaining in each flow path when the insertion hole is formed can be easily taken out to the entry side of the filter body in any flow path, and the plug prevents removal of the processing waste. Since such a situation does not occur, it is possible to easily perform the processing after the drilling of the insertion hole.
[0037]
(IV) The filter body made of a porous material that is brittle in terms of strength can be reliably protected by the cushion material from running vibration of the vehicle, etc., and obstruction of the insertion of the temperature sensor by the cushion material can be reliably avoided.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an embodiment of the present invention.
FIG. 2 is a perspective view showing details of the particulate filter of FIG. 1;
FIG. 3 is a schematic diagram illustrating an arrangement state of a conventional particulate filter.
FIG. 4 is a sectional view showing details of the particulate filter of FIG. 3;
FIG. 5 is a graph showing a temperature distribution in a particulate filter.
FIG. 6 is a graph showing temperature changes of an inlet gas temperature, an outlet gas temperature, and an internal temperature.
[Explanation of symbols]
2 Exhaust gas 5 Flow path 6 Porous thin wall 7 Filter body 8 Plug body 9 Cushion material 10 Filter case 11 Seal material 14 Particulate filter 15 Temperature sensor 16 Insertion hole

Claims (1)

A filter body formed of a porous material integrally supporting an oxidation catalyst and having a plurality of channels formed in a honeycomb shape through which exhaust gas flows, and one of an inlet side and an outlet side of each channel of the filter body And a plug body that alternately plugs in the particulate filter, the particulate filter in the exhaust gas so as to be able to collect the particulates in the exhaust gas by passing through the porous thin walls that define the flow paths, The plug on the inlet side is arranged at a position separated from the inlet side end face of the filter body, and an insertion hole is formed in the radial direction of the filter body so that the temperature sensor can be inserted and installed immediately before the plug on the inlet side. A seal member for airtightly closing a gap between the filter case and the filter case is attached to at least one or more locations on the outer peripheral portion of the filter main body behind the insertion hole, and the rest of the filter main body avoiding the seal material and the insertion hole is attached. of Particulate filter, characterized in that mounting the cushioning member to the peripheral portion.

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