JP4868713B2 - Exhaust gas purification filter device - Google Patents

Description

  The present invention relates to an exhaust gas purification filter device that collects particulate matter (hereinafter referred to as PM) in exhaust gas from a diesel engine or the like.

  Since exhaust gas from diesel engines, etc. contains PM composed of carbon fine particles, SOF, sulfates, etc., it is necessary to remove PM before discharging to discharge clean exhaust gas. Since it is difficult to remove this PM with a normal oxidation catalyst, a three-way catalyst, etc., a method of removing it by oxidation after collecting it on a filter is common.

  As such a filter, a honeycomb body made of heat-resistant ceramics such as cordierite and having a large number of cells, an inflow side cell clogged at the downstream end, and an upstream end adjacent to the inflow side cell A wall flow type in which an outflow side cell clogged with the above is formed is widely used. In this filter, the exhaust gas flowing into the inflow side cell passes through the cell partition wall and is discharged from the outflow side cell, but when the exhaust gas passes through the cell partition wall, PM is collected in the pores of the cell partition wall. When PM is collected to some extent, PM collected by heating with a heater is burned to regenerate the filter function.

  However, with such a filter, when the amount of collected PM is large, the amount of heat generated by combustion during regeneration is large, and may be damaged by heat shock. In addition, the manufacturing cost is high. Therefore, in recent years, several metal filter devices have been proposed.

  For example, in Japanese Patent Application Laid-Open No. 09-262414, a corrugated plate made of a thin metal plate and a flat plate made of a metal non-woven fabric are alternately laminated, and an inflow side cell clogged at a downstream end portion is adjacent to the inflow side cell. A filter is described which forms an outflow side cell clogged at an upstream end. Further, JP 2002-113798 A discloses an inflow side cell in which flat plates and corrugated plates made of a metal nonwoven fabric are alternately laminated and clogged at a downstream end, and an upstream end adjacent to the inflow side cell. And a filter formed with an outflow side cell clogged with.

  According to these filters, PM in the exhaust gas is collected in the metal nonwoven fabric. And even if it performs the regeneration process which burns PM by heating, since it is metal, a heat shock is small and damage can be suppressed. However, since both are wall flow type filters, exhaust pressure loss increases as PM is collected. In addition, since PM concentrates and accumulates in the vicinity of the clogging portion of the inflow side cell, there is a problem that exhaust pressure loss increases at a stretch. When importance is attached to engine efficiency or fuel consumption, it is necessary to frequently perform regeneration processing.

  On the other hand, in German utility model 20,117,873 U1, a corrugated plate made of metal foil and a filter layer are alternately laminated to form a plurality of claw-shaped holes having claw-shaped hole heights on the corrugated plate. The inner hole forms a flow path having an inward nail hole and an outward nail hole, the inward nail hole and the outward nail hole are arranged at an angle with each other, and the nail hole height is equal to the structural height. A filter is described which is 100-60% high and guarantees a flow freedom of at least 20%.

According to this filter, PM is collected in the filter layer by the exhaust gas coming out of the claw-shaped holes passing through the filter layer. However, in this filter device, if PM deposits on the filter layer and the claw portion of the claw-shaped hole, the exhaust gas flow path is blocked and the exhaust pressure loss increases rapidly, so the amount of PM that can be collected is increased. However, there is a disadvantage that the PM collection efficiency must be lowered.
JP 09-262414 A JP 2002-113798 German utility model 20,117,873 U1

  This invention is made | formed in view of such a situation, and makes it a subject to make compatible the improvement of the collection efficiency of PM, and suppression of the raise of exhaust pressure loss.

A feature of the exhaust gas purifying filter device of the present invention that solves the above problems is that a corrugated plate made of a thin metal plate and having a crest and a trough alternately continuous in a direction intersecting the exhaust gas flow direction, and heat-resistant fibers are integrated. The gas permeable flat plates are alternately stacked, the crests and troughs constitute the exhaust gas flow path, and the flat plates constitute the filter.
The valley has a convex intermediate peak formed by the valley depth being shallow, and the peak has a concave intermediate valley formed by the peak height being reduced,
In the part where the flat plate is laminated on the upper side of the corrugated plate,
The intermediate crest and the crests on both sides adjacent to the crest and the flat plate in contact with the crest form a filter introduction part that blocks the flow path and guides exhaust gas to the filter,
The middle valley portion is composed of a branch portion where the exhaust gas branches off from the adjacent valley portion and can flow in, and an opening communicating with the mountain portion on the downstream side, and branches to the exhaust gas flow channel adjacent to the filter introduction portion. Configure the bypass filter part to bypass,
When the pressure in the filter introduction portion increases, at least a part of the exhaust gas flowing through the valley portion passes from the filter introduction portion to the adjacent peak portion through the filter bypass portion existing on the upstream side of the filter introduction portion. That is to be configured.

  In this case, it is desirable that there is a crest of an adjacent corrugated plate on the opposite side of the filter introduction portion through the flat plate.

Moreover, if the characteristics of this exhaust gas purification filter device are expressed from the back side of the corrugated plate, the filter introduction portion in which the flow path is blocked by the intermediate valley portion, the valley portions on both sides adjacent to the intermediate valley portion, and the flat plate in contact with the valley portion The intermediate peak portion constitutes a filter bypass portion consisting of a branch portion into which exhaust gas branches off from an adjacent peak portion and can flow in, and an opening communicating with the valley portion on the downstream side, and the pressure in the filter introduction portion is When the height increases, at least a part of the exhaust gas flowing through the peak portion is configured to flow from the filter introduction portion to the adjacent valley portion through the filter bypass portion existing on the upstream side of the filter introduction portion.

  In this case, it is desirable that a trough portion of an adjacent corrugated plate exists on the opposite side of the filter introduction portion through the flat plate.

  It is desirable that the intermediate valley portion and the intermediate mountain portion are formed by deforming the mountain portion or the valley portion, and that the upstream end portion is smoothly continuous toward the bottom portion or the top portion, respectively.

  Further, the opening area of the corrugated plate in plan view in the filter introduction portion is preferably 30% or more of the total opening area of the corrugated plate in plan view, and the total volume of the filter introduction portion is the total of the peaks and valleys. It is preferably 50% or more of the total volume.

  Furthermore, it is desirable that at least one of the exhaust gas flow path and the filter is formed with a catalyst layer in which a noble metal is supported on a porous oxide carrier.

  According to the exhaust gas purifying filter device of the present invention, when PM accumulates in the filter introduction part and the exhaust pressure loss increases, the exhaust gas branches off from the filter bypass part and flows through the filter bypass part sequentially. However, since it flows to the outflow side end, an increase in exhaust pressure loss is suppressed.

  And since the filter from a filter introduction part to a filter detour part can be used for collection of PM, and the big area of a filter can be used for collection of PM, PM can be collected efficiently. Therefore, the time until the regeneration process for burning the collected PM can be increased.

  The exhaust gas purification filter device of the present invention has a plurality of exhaust gas flow paths and a filter installed in the exhaust gas flow path, and the exhaust gas flow path is adjacent to the filter introduction part that guides the exhaust gas to the filter, and the filter introduction part And a filter bypass section that branches to the exhaust gas flow path that bypasses the filter introduction section.

  The filter can collect PM and has air permeability, and ceramics, fiber aggregates, and the like can be used. By arranging this filter in the exhaust gas flow path, a filter introduction part can be formed, and by bypassing the filter by forming a through hole etc. communicating with the adjacent exhaust gas flow path in the exhaust gas flow path on the upstream side thereof The part can be formed. As a particularly preferred embodiment, it is desirable to make a honeycomb-shaped filter device in which corrugated plates having no air permeability and flat plate filters are alternately laminated.

  As such a filter apparatus, the thing of Claim 2 or Claim 4 is especially preferable. In the exhaust gas purification filter device according to claim 2, the exhaust gas flowing into the flow path formed by the valley portion and the upper flat plate passes through the upper flat plate that collides with the intermediate mountain portion and partitions the filter introduction portion, PM is collected on the flat plate. When the amount of PM trapped on the upper flat plate that partitions the filter introduction portion increases, the pressure in the filter introduction portion increases, so the exhaust gas passes through the branch portion of the filter detour portion on the upstream side from the filter introduction portion, and the peaks on both sides Branch inflows from the middle valley to the peaks on both sides.

  And as described in claim 4, on the back side of the corrugated plate, the back side of the intermediate valley portion is convex to form a filter introduction portion between the peak portion and the lower flat plate, and the upstream valley portion. Since the filter detour part is formed at the intermediate peak of the exhaust gas, the exhaust gas flowing into the flow path formed by the peak and the lower flat plate collides with the intermediate valley and the pressure increases in the filter introduction part From the filter introduction part, it passes through the filter detour part on the upstream side, and branches and flows into the troughs on both sides through the opening of the intermediate peak part of the troughs on both sides.

  This action is continuously repeated from the exhaust gas inflow side end surface to the outflow side end surface.

  That is, since the filter device of the present invention basically has a wall flow structure, the PM collection efficiency is high. Even if the amount of PM trapped on the flat plate in the filter introduction portion increases, the exhaust gas branches off from the upstream filter detour portion and flows into the peak portion or valley portion, which continuously occurs. Therefore, an increase in exhaust pressure loss due to PM accumulation does not occur all at once, and since most of the flat plate can be used for PM collection, an increase in exhaust pressure loss can be effectively suppressed.

  The corrugated plate is formed from a thin metal plate, and is preferably manufactured by corrugating or the like. The material is not particularly limited as long as it has heat resistance that can withstand the exhaust gas temperature and heat during regeneration, but a stainless steel material is preferable. For automobiles, the thickness is preferably in the range of 20 to 110 μm, particularly preferably in the range of 40 to 80 μm.

The flat plate is a gas-permeable member in which heat-resistant fibers are integrated, and can be formed from non-woven fabrics such as metal fibers, ceramic fibers, metal whiskers, and ceramic whiskers, and woven fabrics. In order to achieve both improvement in PM collection efficiency and suppression of increase in exhaust pressure loss as an automobile exhaust gas purification filter device, the fiber diameter is preferably about 15 to 60 μm, and the basis weight is preferably 300 to 1000 g / m ^2. .

  In order to obtain the filter device of the present invention, the corrugated plates and the flat plates may be alternately stacked and inserted into a predetermined outer cylinder, or the corrugated plates and the flat plates of a predetermined length may be overlapped and wound into a roll shape. This can be inserted into a predetermined outer cylinder. Note that the corrugated plates may be laminated so that all layers have the same direction and the same phase, or can be laminated so that the directions are alternately different by 180 degrees or the phases are different. However, when the filter introduction part is formed in the valley part, it is desirable that there is a crest of the adjacent corrugated plate on the opposite side through the flat plate, and the filter introduction part is formed in the crest part. If there is, it is desirable that a trough portion of the adjacent corrugated plate exists on the opposite side through the flat plate. As a result, the PM collection efficiency can be further improved and the increase in exhaust pressure loss can be further suppressed without impeding the flow of the exhaust gas that has permeated the flat plate.

  The intermediate valley portion or the intermediate mountain portion is formed by deforming the mountain portion or the valley portion, and it is desirable that the upstream end portion is smoothly continuous toward the bottom portion or the top portion, respectively. That is, it is preferable that the height is gradually reduced toward the upstream side, or is blocked by a slope that becomes higher. By doing in this way, since the vector which goes to the flat plate which partitions a filter introduction part produces | generates in the exhaust gas in a filter introduction part, PM collection efficiency improves further.

  The opening area of the corrugated plate in plan view in the filter introduction part is desirably 30% or more of the total opening area of the corrugated plate in plan view. When the opening area of the corrugated plate in plan view at the filter introduction portion is less than 30% of the total opening area, the use area of the flat plate is reduced and the PM collection efficiency is reduced. The total volume of the filter introduction part is preferably 50% or more of the total volume of the peak part and the valley part. When this ratio is less than 50%, the PM collection efficiency decreases.

  Also, the longer the distance from the filter introduction part to the upstream branch part, the better the PM collection efficiency, but the exhaust pressure loss tends to increase. Therefore, there is an optimum value for the distance.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
FIG. 1 is a perspective view and an enlarged view of a main part of the filter device of the present embodiment, FIG. 2 is an essential part perspective view of a corrugated plate, and FIGS. This filter device is made by alternately laminating corrugated plate 1 made of stainless steel and having a thickness of 60 μm and flat plate 3 having a basis weight of 450 g / m ² and a thickness of 60 μm made of stainless steel nonwoven fabric. And the outer cylinder 4 in which the filter element is press-fitted and held.

  In the corrugated plate 1 shown in FIG. 2, the crests 10 and the troughs 11 are alternately continued in a direction orthogonal to the exhaust gas flow direction. In the peak portion 10, a plurality of concave intermediate valley portions 12 are formed in parallel to the exhaust gas flow direction and spaced from each other. The intermediate valley portion 12 gradually decreases in height from the upstream side to the downstream side of the exhaust gas, and the tip thereof is cut away to form an opening 13 communicating with the mountain portion 10 again. The depth of the bottom of the intermediate valley 12 is the same as the position of the bottom of the valley 11.

  In the valley portion 11, a plurality of convex intermediate mountain portions 14 are formed in parallel to the exhaust gas flow direction and spaced from each other. The intermediate mountain portion 14 is disposed between the two intermediate valley portions 12 in the exhaust gas flow direction, and the height thereof is the same as the height of the mountain portion 10.

  As shown in FIG. 3, the plurality of corrugated plates 1 are alternately laminated with the flat plate 3 so that the phases of the intermediate valley portions 12 and the intermediate mountain portions 14 are the same in the exhaust gas flow direction and in the direction perpendicular to the exhaust gas flow direction. The intermediate valley portion 12 and the intermediate mountain portion 14 are arranged at the same position in the cross section cut at right angles to the exhaust gas flow direction of the filter element. Further, the peak portion 10 is in contact with the upper flat plate 3, and the valley portion 11 is in contact with the lower flat plate 3.

  In this filter device, as shown in FIGS. 4 to 7, on the surface side of the corrugated plate 1, a filter is introduced in which the flow path is blocked by the peak portions 10 on both sides adjacent to the intermediate peak portion 14 and the upper flat plate 3. Part 100 is formed. Further, on the back side of the corrugated plate 1, a filter introduction portion 101 is formed in which the flow path is closed by the valley portions 11 on both sides adjacent to the intermediate valley portion 12 and the lower flat plate 3. Further, on the upstream side of the filter introduction part 100, the height of the peak part 10 is lowered at the position of the intermediate valley part 12, and the opening 13 is formed, so that the exhaust gas flowing through the valley part 11 flows from the opening 13 on both sides to the both sides. A branch can flow into the mountain portion 10, and a filter bypass portion 200 is formed there. In addition, on the back side, the depth of the valley portion 11 becomes shallow and the opening 15 is formed at the position of the intermediate peak portion 14 on the upstream side of the filter introduction portion 101. Can flow into the troughs 11 on both sides, and the filter bypassing part 201 is also formed there.

  Therefore, according to the exhaust gas purification filter device of the present embodiment, as shown in FIG. 4, the exhaust gas flowing through the flow path formed between the valley portion 11 and the upper flat plate 3 collides with the intermediate mountain portion 14, In a state where the amount of PM trapped on the upper flat plate 3 is small, most of the exhaust gas passes through the upper flat plate 3 and flows into the valleys 11 of the corrugated plate 1 on the opposite side of the flat plate 3, and most of the PM Is collected by the flat plate 3.

  When the amount of collected PM increases and the pressure of the exhaust gas in the filter introduction section 100 increases, the exhaust gas flows backward as shown by the solid line arrow in FIG. 5 and in the filter bypass section 200 existing on the upstream side as shown by the dotted line arrow. The intermediate valley portion 12 passes through the opening 13 and branches into the adjacent mountain portion 10. Therefore, an increase in exhaust pressure loss is suppressed.

  Similarly, the exhaust gas flowing through the flow path formed between the peak portion 10 and the lower flat plate 3 collides with the intermediate valley portion 12 in the filter introduction portion 101 as shown in FIG. When the collected amount is small, most of the exhaust gas passes through the lower flat plate 3 and flows into the valley 11 of the corrugated plate 1 on the opposite side of the flat plate 3, and most of the PM is captured by the flat plate 3. Be collected.

  When the amount of collected PM increases and the pressure of the exhaust gas at the filter introduction unit 101 increases, the exhaust gas flows backward as shown by the solid line arrow in FIG. 7, and the exhaust gas flows upstream as shown by the dotted line arrow. In 201, the water flows into the adjacent valley portion 11 through the opening 15 from the intermediate mountain portion 14 and flows into the adjacent valley portion 11. Therefore, an increase in exhaust pressure loss is suppressed.

  According to the filter device of the present embodiment, PM is collected on the flat plate 3 in the filter introduction parts 100 and 101 by continuously repeating the cycle from the exhaust gas inflow side end face toward the outflow side end face. Since a large number of filter introduction parts 100 and 101 are formed, PM is uniformly dispersed and collected over the entire flat plate 3, and the collection efficiency is improved and PM is collected. Exhaust pressure loss is unlikely to rise. That is, the improvement of the PM collection efficiency and the suppression of the increase of the exhaust pressure loss are compatible.

  Further, in the filter device of the present embodiment, the opening area of the corrugated plate 1 in the plan view in the filter introducing portions 100 and 101 occupies about 40% of the total opening area of the corrugated plate 1 in the plan view. The total volume of 101 occupies about 50% of the total volume of the peak 10 and the valley 11. Thereby, the utilization area of the flat plate 3 is large, the PM collection efficiency is high, and the increase in exhaust pressure loss is suppressed.

(Example 2)
The filter device of this example is the same as that of Example 1 except that the laminated state of the corrugated plates 1 is different. In this filter device, as shown in FIG. 8, corrugated plates 1 similar to those of the first embodiment are laminated while being reversed alternately forward and reverse, that is, alternately by 180 degrees parallel to the surface of the flat plate 3.

  Even in the filter device of the present embodiment, although it is inferior to the first embodiment, the effect of improving the PM collection efficiency and suppressing the increase in exhaust pressure loss is exhibited.

(Comparative example)
The filter apparatus described in Example 1 of German utility model 20,117,873 U1 was used as a comparative example.

  That is, the filter device of the comparative example uses the same corrugated plate 1 as in the first embodiment and is alternately laminated with the flat plate 3 as in the first embodiment, but the exhaust gas inlet side in the first embodiment is on the outlet side, and the outlet Inverted 180 degrees so that the side is the entrance side.

<Test and evaluation>
Using the filter device of Example 1 and the comparative example, the PM collection rate and the exhaust pressure loss were measured. The filter elements are about 1 L each having a diameter of 130 mm and a length of 75 mm, and the number of cells per square inch of the cross section is 200 cells.

  The filter devices of Example 1 and the comparative example were respectively attached to the exhaust pipe of a diesel engine, and PM collection efficiency and exhaust pressure loss during steady running were measured every predetermined time. Since the PM emission amount from the engine is known, the PM amount collected according to the measurement time is calculated, and the measured values of PM collection efficiency and exhaust pressure loss with respect to the collected PM amount are shown in FIG.

  From FIG. 9, it can be seen that the filter device of Example 1 has higher PM collection efficiency than the filter device of the comparative example, and the increase in exhaust pressure loss is suppressed, and these differences are the differences in the structure of the corrugated plate 1. It is clear that this is caused by

  The exhaust gas purification filter device of the present invention may be used as it is, or may be a filter catalyst in which a catalyst metal such as Pt is supported on at least a part of the corrugated plate and the flat plate. The catalyst metal may be directly supported on at least a part of the corrugated plate and the flat plate, or a coating layer made of a porous oxide may be formed and supported on the coating layer. By using such a filter catalyst, PM can be oxidized and burned at the same time as collection, and regeneration processing can be made unnecessary. Moreover, it becomes possible to purify harmful gas components such as HC and CO in the exhaust gas by the catalytic metal.

It is the perspective view and main part expansion perspective view of the filter apparatus of one Example of this invention. It is a principal part perspective view of the corrugated board used for the filter apparatus of one Example of this invention. It is a principal part expanded sectional view of the filter apparatus of one Example of this invention. It is a principal part expanded sectional view of the filter apparatus of one Example of this invention. It is a principal part expanded sectional view of the filter apparatus of one Example of this invention. It is a principal part expanded sectional view of the filter apparatus of one Example of this invention. It is a principal part expanded sectional view of the filter apparatus of one Example of this invention. It is a principal part expanded sectional view which shows the filter apparatus of 2nd Example of this invention. It is a graph which shows the relationship between the PM collection rate with respect to the PM collection amount of the filter apparatus of an Example and a comparative example, and exhaust pressure loss.

Explanation of symbols

1: Corrugated plate 3: Flat plate 4: Outer tube 10: Mountain
11: Valley 12: Middle valley 13: Opening 14: Middle mountain
15: Opening 100, 101: Filter introduction part 200, 201: Filter bypass part

Claims (6)

A corrugated plate made of a thin metal plate and alternately continuous in a direction in which peaks and troughs intersect the exhaust gas flow direction, and a gas permeable flat plate in which heat-resistant fibers are accumulated, are alternately laminated, The peak portion and the valley portion constitute an exhaust gas flow path, and the flat plate is an exhaust gas purification filter device constituting a filter,
The valley has a convex intermediate peak formed by a shallow valley depth, the peak has a concave intermediate valley formed by a low peak height,
In the portion where the flat plate is laminated on the upper side of the corrugated plate,
A flow path is blocked by the intermediate crests and the crests on both sides adjacent to the intermediate crests and the flat plate in contact with the crests to constitute a filter introduction part that guides exhaust gas to the filter;
The intermediate valley portion includes a branch portion into which exhaust gas branches off from the adjacent valley portion, and an opening communicating with the peak portion on the downstream side, and branches into the exhaust gas flow channel adjacent to the filter introduction portion. A filter bypass unit that bypasses the filter introduction unit,
When the pressure in the filter introduction part increases, at least a part of the exhaust gas flowing through the valley part passes through the filter bypass part existing upstream from the filter introduction part and is adjacent to the mountain. An exhaust gas purifying filter device configured to flow into a section.   2. The exhaust gas purification filter device according to claim 1, wherein the peak portion of the adjacent corrugated plate is present on the opposite side of the filter introduction portion through the flat plate. The said intermediate | middle valley part and the said intermediate | middle peak part are formed by deform | transforming the said peak part or the said valley part, respectively, and each upstream end part is continuing smoothly toward the bottom part or the top part. Exhaust gas purification filter device. The total value of the opening area in plan view of the valley from the filter introduction part to the position of the opening of the filter bypass part existing upstream is 30% or more of the total opening area of the valley in plan view The exhaust gas purification filter device according to claim 1. 2. The exhaust gas purification according to claim 1, wherein a total volume of the valley portion from the filter introduction portion to a position of an opening of the filter bypass portion existing upstream thereof is 50% or more of a total total volume of the valley portion. Filter device. The exhaust gas purification filter device according to claim 1, wherein a catalyst layer in which a noble metal is supported on a porous oxide carrier is formed in at least one of the exhaust gas flow path and the filter.

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