JP7566005B2 - Cylindrical member for exhaust gas treatment device, electrically heated member for exhaust gas treatment device, and exhaust gas treatment device - Google Patents

Description

The present invention relates to a cylindrical member for an exhaust gas treatment device, an electrically heated member for an exhaust gas treatment device, and an exhaust gas treatment device.

Conventionally, a catalyst supported on a columnar honeycomb structure has been used to purify harmful substances such as HC, CO, and NOx contained in exhaust gas emitted from engines of vehicles. When treating exhaust gas with a catalyst supported on a honeycomb structure, the catalyst needs to be heated to its activation temperature, but when the engine is started, the catalyst has not yet reached its activation temperature, which causes a problem that exhaust gas is not sufficiently purified. In particular, plug-in hybrid vehicles (PHEVs) and hybrid vehicles (HVs) include driving using only the motor, so the engines are started infrequently and the catalyst temperature at engine start is low, which means that exhaust gas purification performance is likely to decrease immediately after engine start.

Therefore, an electrically heated catalyst (EHC) has been proposed, which heats an electrically heated carrier (for example, an electrically heated honeycomb structure) by providing a pair of electrodes on the electrically heated carrier and passing electricity through the electrodes. This electrically heated catalyst is used with the electrically heated carrier housed in a cylindrical member (cylindrical container). When electricity is passed through the electrically heated carrier, electricity also flows through the cylindrical member, so an insulating mat material is generally placed between the electrically heated carrier and the cylindrical member. In addition, since the mat material may absorb moisture in a high-temperature humid environment and its insulating properties may decrease, Patent Documents 1 and 2 propose providing an insulating layer on the inner surface of the cylindrical member that contacts the mat material.

Patent No. 5408341 Patent No. 5864213

The electrically heated carrier housed in the tubular member is held in place by friction between the inner circumferential surface of the tubular member. In order to hold the electrically heated carrier in a predetermined position in the tubular member, this friction must be greater than the sum of the exhaust gas pressure and the external forces due to vehicle vibration.
However, due to the presence of a pair of electrodes provided on the outer peripheral surface of the electrically heated carrier, the outer peripheral area of the electrically heated carrier in contact with the inner peripheral surface of the cylindrical member is reduced, making it difficult to ensure sufficient friction between the outer peripheral surface of the electrically heated carrier and the inner peripheral surface of the cylindrical member. In addition, since the coefficient of friction of the insulating layer tends to be small, providing an insulating layer on the inner peripheral surface of the cylindrical member tends to further reduce the friction between the outer peripheral surface of the electrically heated carrier. As a result, the electrically heated carrier accommodated in a predetermined position of the cylindrical member is easily displaced by external forces due to exhaust gas pressure and vehicle vibration. In order to increase the friction between the outer peripheral surface of the electrically heated carrier and the inner peripheral surface of the cylindrical member, it is possible to increase the surface pressure of the cylindrical member against the electrically heated carrier, but in this case, there is a risk that the electrically heated carrier will crack.

The present invention has been made to solve the above-mentioned problems, and aims to provide a tubular member for an exhaust gas treatment device that is capable of increasing the frictional force against the outer peripheral surface of an electrically heated carrier, and an exhaust gas treatment device that uses this tubular member for an exhaust gas treatment device.
Another object of the present invention is to provide an electrically heated member for exhaust gas treatment equipment that is capable of increasing the frictional force against the inner surface of a cylindrical member, and an exhaust gas treatment equipment using this electrically heated member for exhaust gas treatment equipment.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered that by providing an insulating layer having an uneven portion and a static friction coefficient of 0.30 or more on the inner surface of a cylindrical metal member or the outer surface of an electrically heated carrier, it is possible to increase the frictional force between the outer surface of the electrically heated carrier and the inner surface of the cylindrical member, thus completing the present invention.

In other words, the present invention provides a tubular member for an exhaust gas treatment device, comprising a tubular metal member and an insulating layer provided on the inner surface of the tubular metal member, the surface of the insulating layer having uneven portions with a height difference of 300 μm or less and a static friction coefficient of 0.30 or more, and the insulating layer having a porosity of 10% or less and containing at least silicate glass or borosilicate glass.

The present invention also relates to an exhaust gas treatment device comprising a columnar electrically heated carrier capable of heating exhaust gas, and a cylindrical member for the exhaust gas treatment device that houses the electrically heated carrier.

The present invention also relates to an electrically heated component for an exhaust gas treatment device, comprising a columnar electrically heated carrier capable of heating exhaust gas, and an insulating layer provided on at least the outer peripheral surface of the electrically heated carrier, wherein the surface of the insulating layer has uneven portions with a height difference of 300 μm or less and a static friction coefficient of 0.30 or more, and the insulating layer has a porosity of 10% or less and is a layer containing at least silicate glass or borosilicate glass.

Furthermore, the present invention is an exhaust gas treatment device comprising an electrically heated member for an exhaust gas treatment device and a cylindrical metal member that houses the electrically heated member for an exhaust gas treatment device.

According to the present invention, it is possible to provide a tubular member for an exhaust gas treatment device capable of increasing the frictional force against the outer peripheral surface of an electrically heated carrier, and an exhaust gas treatment device using this tubular member for an exhaust gas treatment device.
Furthermore, according to the present invention, it is possible to provide an electrically heated member for an exhaust gas treatment device that is capable of increasing the frictional force against the inner surface of a cylindrical member, and an exhaust gas treatment device that uses this electrically heated member for an exhaust gas treatment device.

1 is a cross-sectional view perpendicular to the flow direction of exhaust gas of a cylindrical member for an exhaust gas treatment device according to a first embodiment of the present invention. 2 is a partially enlarged cross-sectional view of the cylindrical member for an exhaust gas treatment device shown in FIG. 1 along line a-a'. 3 is a development view of a portion of a surface of an insulating layer in the tubular member for an exhaust gas treatment device of FIGS. 1 and 2. FIG. 4 is a development view of a portion of the surface of another insulating layer in a cylindrical member for an exhaust gas treatment device according to the first embodiment of the present invention, and a cross-sectional view taken along line d-d' thereof. FIG. 1 is a cross-sectional view perpendicular to the flow direction of exhaust gas of an exhaust gas treatment device according to a first embodiment of the present invention. A cross-sectional view of the exhaust gas treatment device of Figure 5 along line b-b'. 5 is a cross-sectional view perpendicular to the exhaust gas flow direction of an electrically heated member for an exhaust gas treatment device according to a second embodiment of the present invention. FIG. 8 is a partially enlarged cross-sectional view of the electrically heated member for an exhaust gas treatment device shown in FIG. 7 along line c-c'.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment, and it should be understood that modifications and improvements to the following embodiment, as appropriate, based on the ordinary knowledge of a person skilled in the art, fall within the scope of the present invention, provided that they do not deviate from the spirit of the present invention.

(Embodiment 1)
Fig. 1 is a cross-sectional view perpendicular to the exhaust gas flow direction of a tubular member for an exhaust gas treatment device according to a first embodiment of the present invention. Fig. 2 is a partially enlarged cross-sectional view of the line aa' in the tubular member for an exhaust gas treatment device in Fig. 1. Fig. 3 is a development view of a part of the surface of an insulating layer in the tubular member for an exhaust gas treatment device in Figs. 1 and 2.
The tubular member 100 for an exhaust gas treatment device comprises a tubular metal member 10 and an insulating layer 20 provided on the inner peripheral surface of the tubular metal member 10 .

The cylindrical metal member 10 is a member capable of accommodating a columnar electrically heated carrier. The axial direction of the cylindrical metal member 10 preferably coincides with the axial direction of the columnar electrically heated carrier, and the central axis of the cylindrical metal member 10 preferably coincides with the central axis of the columnar electrically heated carrier. In addition, it is preferable that the central position in the axial direction of the cylindrical metal member 10 coincides with the central position in the axial direction of the columnar electrically heated carrier. Furthermore, the cylindrical metal member 10 may be uniform along the axial direction, but at least a portion (e.g., both axial ends, etc.) may have a reduced or increased diameter.

The arithmetic surface roughness Ra of the inner peripheral surface of the tubular metal member 10 is preferably 10 μm or less, more preferably 8 μm or less. By controlling the arithmetic surface roughness Ra within such a range, the insulating layer 20 can be uniformly formed on the inner peripheral surface of the tubular metal member 10. Moreover, the arithmetic surface roughness Ra of the inner peripheral surface is preferably 1 μm or more, more preferably 2 μm or more. By controlling the arithmetic surface roughness Ra within such a range, the adhesive force of the insulating layer 20 to the inner surface of the tubular metal member 10 can be increased by the anchor effect.
In this specification, the term "arithmetic surface roughness Ra" refers to the average of Z(x) in the reference length of the roughness curve, and is measured in accordance with JIS B0601:2013.

The material of the cylindrical metal member 10 is not particularly limited, but is preferably a metal from the viewpoint of manufacturability. Examples of materials for the cylindrical metal member 10 include stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, etc. Among these, stainless steel is preferred because of its high durability, reliability, and low cost.

The thickness of the tubular metal member 10 is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more. By making the thickness of the tubular metal member 10 0.1 mm or more, durability and reliability can be ensured. In addition, the thickness of the tubular metal member 10 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. By making the thickness of the tubular metal member 10 10 mm or less, the weight of the tubular member 100 for the exhaust gas treatment device can be reduced.

The surface of the insulating layer 20 has an uneven portion 21. By providing the uneven portion 21, the friction coefficient of the insulating layer 20 increases, and therefore the frictional force between the surface of the insulating layer 20 and the outer circumferential surface of the columnar electrically heated carrier in contact with the surface of the insulating layer 20 can be increased.
In this specification, the term "uneven portion 21" refers to a portion that is recessed (concave portion) and/or a portion that protrudes (convex portion) from a flat surface. Note that Figs. 1 to 3 show an example having only a portion that is recessed (concave portion) from a flat surface.

The surface of the insulating layer 20 has a static friction coefficient of 0.30 or more, preferably 0.35 or more, and more preferably 0.40 or more. By controlling the static friction coefficient within such a range, it is possible to ensure a frictional force capable of suppressing the displacement (movement in the direction of the exhaust gas flow) of the electrically heated carrier caused by external forces due to exhaust gas pressure and vehicle vibration. The upper limit of the static friction coefficient is not particularly limited, but is generally 1.0 or less.
In this specification, the term "static friction coefficient" refers to the static friction coefficient measured at 23° C. in accordance with JIS K7125:1999.

The height difference of the uneven portion 21 of the insulating layer 20 is preferably 300 μm or less, more preferably 280 μm or less, and even more preferably 250 μm or less. By controlling the height difference of the uneven portion 21 within such a range, it is possible to sufficiently ensure the frictional force between the surface of the insulating layer 20 and the outer peripheral surface of the columnar electrically heated carrier. The lower limit of the height difference of the uneven portion 21 is not particularly limited, but is generally 4 μm or more, preferably 10 μm or more.
In this specification, the "height difference of the uneven portion 21" means the height difference between the lowest point and the highest point in a cross-sectional view of the insulating layer 20 parallel to the flow direction of the exhaust gas.

The surface of the insulating layer 20 has a ratio of the uneven portion 21 of preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more. By controlling the ratio of the uneven portion 21 within such a range, it is possible to sufficiently ensure the frictional force between the surface of the insulating layer 20 and the outer peripheral surface of the columnar electrically heated carrier. The upper limit of the ratio of the uneven portion 21 is not particularly limited, but is generally 90% or less, and preferably 80% or less.
Here, in this specification, the "proportion of the uneven portion 21" means the total proportion of the concave and convex portions in the entire surface of the insulating layer 20. The proportion of the uneven portion 21 can be calculated by determining the length of the uneven portion 21 relative to the entire length of the insulating layer 20 in the exhaust gas flow direction in a cross-sectional view of the insulating layer 20 parallel to the exhaust gas flow direction.

The surface structure of the insulating layer 20 (shape of the uneven portion 21) is not particularly limited, but may have a groove-shaped recess 22 as shown in Figs. 2 and 3. The surface of the insulating layer 20 may have a substantially hemispherical protrusion 23 as shown in Fig. 4. Fig. 4(A) is a development of a part of the surface of the insulating layer 20, and Fig. 4(B) is a cross-sectional view of the dd' line in Fig. 4(A). Furthermore, although not shown, the surface of the insulating layer 20 may have both recesses 22 of various shapes and protrusions 23 of various shapes. By making the insulating layer 20 have such recesses 22 and/or protrusions 23 on the surface, the frictional force between the surface of the insulating layer 20 and the outer circumferential surface of the columnar electrically heated carrier can be sufficiently ensured.
In this specification, the term "approximately hemispherical" is a concept that includes not only a hemispherical shape but also a semi-elliptical spherical shape.

The insulating layer 20 has a porosity of preferably 10% or less, more preferably 8% or less. By setting the porosity within such a range, the denseness of the insulating layer 20 can be ensured, and therefore deterioration of the insulating properties due to the penetration of moisture can be suppressed.
In this specification, the term "porosity" refers to the porosity measured by mercury intrusion porosimetry.

The thickness of the insulating layer 20 is not particularly limited, but is preferably 600 μm or less, and more preferably 450 μm or less. By controlling the thickness within this range, it is possible to make it difficult for the insulating layer 20 to peel off from the inner surface of the tubular metal member 10. In addition, the thickness of the insulating layer 20 is preferably 20 μm or more, and more preferably 50 μm or more. By controlling the thickness within this range, it is possible to stably ensure insulation between the columnar electrically heated carrier and the tubular metal member 10.

The insulating layer 20 is preferably, but not limited to, a layer containing glass. Examples of glass include silicate glass and borosilicate glass. Among them, silicate glass containing barium is preferable. By using such a layer containing glass, an insulating layer 20 having excellent durability even at high temperatures can be constructed.

The method of forming the uneven portion 21 on the surface of the insulating layer 20 is not particularly limited, and can be performed according to a method known in the art. For example, after forming the insulating layer 20 having a flat surface, the uneven portion 21 can be formed on the surface by pressing a mold corresponding to the uneven portion 21. Also, after forming the insulating layer 20 having a flat surface, the uneven portion 21 can be formed by spraying a highly viscous insulating layer forming slurry. Furthermore, by using a material to which various fillers are added as the material for forming the insulating layer 20, the uneven portion 21 can be formed so that the surface shape of the insulating layer 20 follows the shape of the filler. The filler is not particularly limited, and a filler known in the art (e.g., inorganic oxide) can be used.

The cylindrical member 100 for an exhaust gas treatment device having the above-mentioned characteristics can be used in an exhaust gas treatment device. The exhaust gas is not particularly limited, but is preferably exhaust gas from a vehicle such as an automobile.
A cross-sectional view perpendicular to the exhaust gas flow direction of the exhaust gas treatment device according to the first embodiment of the present invention is shown in Fig. 5. Also, a cross-sectional view of the exhaust gas treatment device taken along line bb' in Fig. 5 is shown in Fig. 6.
As shown in Figures 5 and 6, the exhaust gas treatment device 500 comprises a columnar electrically heated carrier 200 (e.g., a honeycomb structure 50) capable of heating exhaust gas, and a cylindrical member 100 for an exhaust gas treatment device that houses the electrically heated carrier 200.
As described above, the tubular member 100 for exhaust gas treatment equipment has an insulating layer 20 on the inner surface of the tubular metal member 10, which has an uneven portion 21 and a static friction coefficient of 0.30 or more, thereby increasing the frictional force with the outer surface of the electrically heated carrier 200.Therefore, the exhaust gas treatment equipment 500 can suppress shifting of the electrically heated carrier 200 (movement in the direction of exhaust gas flow) caused by external forces due to exhaust gas pressure and vehicle vibration.

In the exhaust gas treatment device 500, the gripping pressure applied from the exhaust gas treatment device cylindrical member 100 to the outer peripheral surface of the electrically heated carrier 200 in a direction perpendicular to the exhaust gas flow direction is preferably 0.2 to 2.0 MPa. By controlling the gripping pressure within this range, it is possible to stably suppress the displacement (movement in the exhaust gas flow direction) of the electrically heated carrier 200 caused by the exhaust gas pressure and external forces due to vehicle vibration.
Here, the gripping pressure can be determined by using a thin sensor sheet to measure the pressure applied to the outer peripheral surface of the electrically heated carrier 200 at room temperature (25° C.). Specifically, the gripping pressure is determined by wrapping a tactile sensor around the outer peripheral surface of the electrically heated carrier 200 and housing it in the exhaust gas treatment device cylindrical member 100, and measuring the pressure applied to the outer peripheral surface of the electrically heated carrier 200 from the pressure read by the tactile sensor.

It is preferable that the exhaust gas treatment device 500 further includes a pair of electrode parts 60 joined to the outer peripheral surface of the electrically heated carrier 200. The pair of electrode parts 60 are arranged in a band shape extending in the exhaust gas flow direction on the outer peripheral surface of the electrically heated carrier 200, sandwiching the central axis of the electrically heated carrier 200. With this configuration, the electrically heated carrier 200 can be heated by applying a voltage between the pair of electrode parts 60.

The electrically heated carrier 200 is not particularly limited, but is preferably a honeycomb structure 50 having an outer peripheral wall 51 and partition walls 55 arranged inside the outer peripheral wall 51 and partitioning a plurality of cells 54 that form a flow path from a first end face 52 to a second end face 53. The honeycomb structure 50 may have plugging portions formed at the ends of the cells 54 on either the first end face 52 side or the second end face 53 side.

The material of the honeycomb structure 50 (the outer peripheral wall 51 and the partition walls 55) is not particularly limited as long as it can generate heat by Joule heat when electricity is applied, and metals, ceramics, etc. can be used.
When ceramics are used as the material of the honeycomb structure 50, at least one ceramic selected from the group consisting of oxide ceramics such as alumina, mullite, zirconia, and cordierite, and non-oxide ceramics such as silicon carbide, silicon nitride, and aluminum nitride can be used. In addition, silicon carbide-metal silicon composite material and silicon carbide/graphite composite material can also be used. Among these, from the viewpoint of achieving both heat resistance and electrical conductivity, it is preferable that the material of the honeycomb structure 50 contains a silicon-silicon carbide composite material or a ceramic containing silicon carbide as the main component. When the material of the honeycomb structure 50 is said to contain a silicon-silicon carbide composite material as the main component, it means that the honeycomb structure 50 contains 90 mass% or more of the silicon-silicon carbide composite material (total mass) of the entirety. Here, the silicon-silicon carbide composite material contains silicon carbide particles as aggregates and silicon as a binder for binding the silicon carbide particles, and it is preferable that a plurality of silicon carbide particles are bound by silicon so as to form pores between the silicon carbide particles. When the material of the honeycomb structure 50 is said to be mainly composed of silicon carbide, it means that the honeycomb structure 50 contains silicon carbide (total mass) in an amount of 90 mass% or more of the entire material.
When the honeycomb structure 50 contains a silicon-silicon carbide composite material, the ratio of the "mass of silicon as a binder" to the total of the "mass of silicon carbide particles as aggregate" and the "mass of silicon as a binder" contained in the honeycomb structure 50 is preferably 10 to 40 mass%, and more preferably 15 to 35 mass%. When this ratio is 10 mass% or more, the strength of the honeycomb structure 50 is sufficiently maintained. Also, when this ratio is 40 mass% or less, the shape is easily maintained during firing.

The thermal expansion coefficient of the honeycomb structure 50 is not particularly limited, but is preferably 3.5 to 6.0 ppm/K, more preferably 3.5 to 4.5 ppm/K, from the viewpoint of thermal shock resistance. In this specification, "thermal expansion coefficient" refers to the linear thermal expansion coefficient at 25 to 800°C measured by a method conforming to JIS R1618:2002, unless otherwise specified. As a thermal dilatometer, "TD5000S (product name)" manufactured by Bruker AXS can be used.

When a voltage is applied between the pair of electrode portions 60, the honeycomb structure 50 is capable of generating heat through Joule heat when electricity is passed through it. Therefore, the honeycomb structure 50 can be suitably used as a heater. The voltage to be applied is preferably 12 to 900 V, but the voltage to be applied can be changed as appropriate. In addition, by supporting a catalyst on the honeycomb structure 50, the honeycomb structure 50 can be used as an EHC.

There is no particular limitation on the volume resistivity of the honeycomb structure 50, so long as it can generate heat by Joule heat. The volume resistivity of the honeycomb structure 50 may be appropriately selected depending on the application. For example, the volume resistivity of the honeycomb structure 50 may be 0.01 to 200 Ωcm, preferably 0.05 to 50 Ωcm, and more preferably 0.1 to 5 Ωcm. The volume resistivity of the honeycomb structure 50 is a value measured at room temperature (25°C) by a four-terminal method.

The partition wall 55 may be porous or dense. When the partition wall 55 is porous, the porosity of the partition wall 55 is not particularly limited, but is preferably 35 to 60%, and more preferably 35 to 45%. The porosity is a value measured by a mercury porosimeter.

The average pore diameter of the partition wall 55 is not particularly limited, but is preferably 2 to 15 μm, and more preferably 3 to 8 μm. The average pore diameter is a value measured by a mercury porosimeter.

The thickness of the partition 55 is not particularly limited, but is preferably 0.1 to 0.3 mm, and more preferably 0.1 to 0.15 mm.

The cell density is not particularly limited, but is preferably 40 to 150 cells/cm ² , and more preferably 60 to 100 cells/cm ² in a cross section of the cells 54 perpendicular to the flow path direction.

The shape of the cells 54 in a cross section perpendicular to the flow direction of the cells 54 is not particularly limited, but is preferably a rectangle, a hexagon, an octagon, or a combination of these. Among these, a square and a hexagon are preferable. By making the cells 54 in this shape, the pressure loss when exhaust gas flows through the honeycomb structure 50 is reduced, and the purification performance of the catalyst can be improved.

The external shape of the honeycomb structure 50 is not particularly limited as long as it is columnar, and can be, for example, a columnar shape with circular, oval, or polygonal (e.g., rectangular, pentagonal, hexagonal, heptagonal, or octagonal) end faces.
From the viewpoint of thermal shock resistance, the size of the honeycomb structure 50 is such that the area of the end face is preferably 2000 to 20000 mm ² , more preferably 4000 to 17000 mm ² .
The length of the honeycomb structure 50 in the central axis direction is preferably 30 to 200 mm, and more preferably 30 to 120 mm, from the viewpoint of thermal shock resistance.

The manufacturing method of the honeycomb structure 50 is not particularly limited, and can be performed according to a method known in the art. For example, first, metal silicon powder (metal silicon), binder, surfactant, pore former, water, etc. are added to silicon carbide powder (silicon carbide) to prepare a molding raw material. Next, the obtained molding raw material is kneaded to form a clay, and the clay is extruded to produce a honeycomb molded body. When extruding, a die having a desired overall shape, cell shape, partition wall thickness, cell density, etc. can be used. Next, the obtained honeycomb molded body is dried and then fired to produce the honeycomb structure 50.

The material of the electrode portion 60 is not particularly limited, but metals and conductive ceramics can be used. Examples of metals include Ag, Cu, Ni, Au, Pd, Cr, Fe, Co, Ni, Si, or Ti single metals, or alloys containing at least one metal selected from the group consisting of these metals. Examples of conductive ceramics include metal compounds such as silicon carbide (SiC) and metal silicides such as tantalum silicide (TaSi ₂ ) and chromium silicide (CrSi ₂ ). In addition, a composite material (cermet) consisting of a combination of one or more of the above conductive ceramics and one or more of the above metals may be used. Specific examples of the cermet include a composite material of metal silicon and silicon carbide, a composite material of metal silicide such as tantalum silicide or chromium silicide, metal silicon, and silicon carbide, and further a composite material in which one or more of the above metals are added with one or more insulating ceramics such as alumina, mullite, zirconia, cordierite, silicon nitride, and aluminum nitride from the viewpoint of reducing thermal expansion. As the material of the electrode portion 60, among the above various metals and conductive ceramics, a combination of a metal silicide such as tantalum silicide or chromium silicide and a composite material of metal silicon and silicon carbide is preferable because it can be fired simultaneously with the honeycomb structure 50, which contributes to simplifying the manufacturing process.

The thickness of the electrode portion 60 is preferably 0.01 to 5 mm, and more preferably 0.01 to 3 mm. By setting the thickness within this range, it becomes easier to uniformly generate heat in the honeycomb structure 50. The thickness of the electrode portion 60 is defined as the thickness in the normal direction to the tangent line at the measurement point on the outer surface of the electrode portion 60 when the portion of the electrode portion 60 to be measured for thickness is observed in a cross section perpendicular to the extension direction of the cells 54.
The electrical resistivity of the electrode portion 60 is preferably lower than that of the honeycomb structure 50. With such a configuration, electricity flows preferentially through the electrode portion 60, so that electricity spreads easily in the flow direction and circumferential direction of the cell 54 when energized. The electrical resistivity of the electrode portion 60 is preferably 1/10 or less of the electrical resistivity of the honeycomb structure 50, more preferably 1/20 or less, and even more preferably 1/30 or less. However, if the difference in electrical resistivity between the two becomes too large, current will concentrate between the ends of the opposing electrode portions 60, causing the heat generation of the honeycomb structure 50 to be biased. Therefore, the electrical resistivity of the electrode portion 60 is preferably 1/200 or more of the electrical resistivity of the honeycomb structure 50, more preferably 1/150 or more, and even more preferably 1/100 or more. In the present invention, the electrical resistivity of the electrode portion 60 is a value measured at 25° C. by a four-terminal method.

The method for forming the electrode portion 60 is not particularly limited, and can be performed according to a method known in the art. For example, a paste or slurry for forming the electrode portion can be applied to the outer peripheral surface of the honeycomb structure 50 using a method such as screen printing, and then fired. The paste or slurry for forming the electrode portion can be fired simultaneously with the firing of the honeycomb molded body.

A mat material may be further provided between the electrically heated carrier 200 and the cylindrical member 100 for an exhaust gas treatment device. The mat material functions as a buffer material and can suppress damage to the electrically heated carrier 200. In addition, if the mat material is insulating, it can suppress electricity from flowing to the cylindrical metal member 10 when electricity is applied to the electrically heated carrier 200.
The mat material is not particularly limited, but preferably contains inorganic fibers such as ceramic fibers. The ceramic fibers preferably contain one or a composite of alumina, mullite, silicon carbide, silicon nitride, zirconia, and titania.

(Embodiment 2)
Fig. 7 is a cross-sectional view perpendicular to the exhaust gas flow direction of the electrically heated member for exhaust gas treatment equipment according to the second embodiment of the present invention. Also, Fig. 8 is a partially enlarged view of the cross section of the line cc' in the electrically heated member for exhaust gas treatment equipment of Fig. 7.
In the exhaust gas treatment device tubular member 100 according to the first embodiment of the present invention, the insulating layer 20 is formed on the inner peripheral surface of the tubular metal member 10 that contacts the outer peripheral surface of the electrically heated carrier 200, whereas in the exhaust gas treatment device electrically heated member according to the second embodiment of the present invention, the insulating layer 20 is formed on the outer peripheral surface of the electrically heated carrier 200 that contacts the inner peripheral surface of the tubular metal member 10. That is, the exhaust gas treatment device electrically heated member according to the second embodiment of the present invention is basically the same as the exhaust gas treatment device tubular member 100 according to the first embodiment of the present invention, except that the member on which the insulating layer 20 is formed is different. Therefore, components having the same reference numerals as those appearing in the description of the first embodiment of the present invention are the same as the components of the second embodiment of the present invention, and therefore will not be described.

As shown in FIGS. 7 and 8 , an electrically heated component 300 for an exhaust gas treatment device comprises a columnar electrically heated carrier 200 capable of heating exhaust gas, and an insulating layer 20 provided on at least the outer peripheral surface of the electrically heated carrier 200 .
The insulating layer 20 provided on at least the outer peripheral surface of the electrically heated carrier 200 has the characteristics described in the first embodiment of the present invention. In particular, by providing the insulating layer 20 having the uneven portion 21 and a surface with a static friction coefficient of 0.30 or more, the friction coefficient of the insulating layer 20 is increased, and therefore the frictional force between the surface of the insulating layer 20 and the inner peripheral surface of the cylindrical metal member 10 in contact with the surface of the insulating layer 20 can be increased. As a result, a frictional force capable of suppressing the displacement (movement in the exhaust gas flow direction) of the electrically heated member 300 for exhaust gas treatment equipment caused by external forces due to exhaust gas pressure and vehicle vibration can be secured.

It is preferable that the electrically heated component 300 for exhaust gas treatment equipment further comprises a pair of electrode parts 60 joined to the outer peripheral surface of the electrically heated carrier 200. In this case, the insulating layer 20 is formed on the outer peripheral surface of the electrically heated carrier 200 and the pair of electrode parts 60 (excluding the external connection parts).

The electrically heated component 300 for exhaust gas treatment equipment having the above-mentioned characteristics can be used in exhaust gas treatment equipment.
The exhaust gas treatment device according to the second embodiment of the present invention includes an electrically heated member for an exhaust gas treatment device 300 and a cylindrical metal member 10 that houses the electrically heated member for an exhaust gas treatment device 300 .
As described above, the electrically heated member 300 for exhaust gas treatment equipment has an uneven portion 21 on the outer peripheral surface of the electrically heated carrier 200 and is provided with an insulating layer 20 having a static friction coefficient of 0.30 or more, thereby increasing the frictional force with the inner peripheral surface of the tubular metal member 10.Therefore, the exhaust gas treatment equipment can suppress shifting (movement in the direction of exhaust gas flow) of the electrically heated member 300 for exhaust gas treatment equipment caused by external forces due to exhaust gas pressure and vehicle vibration.

The exhaust gas treatment device according to the second embodiment of the present invention can further include a mat material between the electrically heated member 300 for exhaust gas treatment device and the cylindrical metal member 10. The mat material functions as a buffer material, and can suppress damage to the electrically heated member 300 for exhaust gas treatment device. In addition, if the mat material is insulating, it can suppress the flow of electricity to the cylindrical metal member 10 when the electrically heated member 300 for exhaust gas treatment device is energized. The materials exemplified above can be used as the mat material.

The exhaust gas treatment device according to the second embodiment of the present invention may use the cylindrical member 100 for an exhaust gas treatment device according to the first embodiment of the present invention as the cylindrical metal member 10. By adopting such a configuration, the frictional force between the outer peripheral surface of the electrically heated member 300 for an exhaust gas treatment device and the inner peripheral surface of the cylindrical member 100 for an exhaust gas treatment device can be further increased.

The present invention will now be described in more detail with reference to the following examples, but the present invention is not limited to these examples in any way.

Example 1
The surface of the SUS430 flat plate was sandblasted for 1 minute using alumina abrasive grains #24-60. The arithmetic surface roughness Ra of the surface after the sandblasting was measured and found to be 3.7 μm. Next, 100 parts by mass of water was added to 100 parts by mass of silicate glass powder containing barium, and the mixture was wet mixed in a ball mill to obtain a slurry for forming an insulating layer. Next, the slurry for forming an insulating layer was spray-coated on the surface of the SUS430 flat plate and dried to obtain a dry coating layer having a flat surface. Next, in order to form groove-shaped recesses 22 as shown in FIGS. 2 and 3 on the surface of this dry coating layer, a mold having protrusions corresponding to the recesses 22 was pressed against the surface of the dry coating layer, and then the mixture was heated at 860° C. for 10 minutes to form an insulating layer having recesses 22 on its surface. This insulating layer had a thickness of 300 μm, a porosity of 9%, a height difference of the recesses 22 of the recesses 22 of 23 μm, and a ratio of the recesses 22 of 66%.

Example 2
The surface of the SUS430 plate was sandblasted for 1 minute using alumina abrasive grains #24-60. The arithmetic surface roughness Ra of the surface after the sandblasting was measured and found to be 3.7 μm. Next, 100 parts by mass of water was added to 100 parts by mass of silicate glass powder containing barium, and the mixture was wet-mixed in a ball mill to obtain a slurry for forming a first insulating layer. Also, 45 parts by mass of water was added to 100 parts by mass of silicate glass powder containing barium, and the mixture was wet-mixed in a ball mill to obtain a slurry for forming a second insulating layer. Next, the slurry for forming the first insulating layer was spray-coated on the surface of the SUS430 plate and dried to obtain a dry coating layer having a flat surface. Next, the slurry for forming the second insulating layer was spray-coated on the dry coating layer and dried to form a substantially hemispherical convex portion 23 on the surface as shown in FIG. 4, and then heated at 860° C. for 10 minutes to form an insulating layer having the convex portion 23 on its surface. This insulating layer had a thickness of 300 μm, a porosity of 5%, a height difference of the uneven portion (protrusions 23) of 23 μm, and a ratio of the uneven portion (protrusions 23) of 80%.

(Comparative Example 1)
The surface of the SUS430 plate was sandblasted for 1 minute using alumina abrasive grains #24-60. The arithmetic surface roughness Ra of the surface after the sandblasting was measured and found to be 3.7 μm. Next, 100 parts by mass of water was added to 100 parts by mass of silicate glass powder containing barium, and the mixture was wet mixed in a ball mill to obtain a slurry for forming an insulating layer. Next, the slurry for forming an insulating layer was spray-coated on the surface of the SUS430 plate and dried to obtain a dry coating layer having a flat surface, and then heated at 860° C. for 10 minutes to form an insulating layer having a flat surface. This insulating layer had a thickness of 300 μm and a porosity of 9%. In Comparative Example 1, no unevenness was formed in the insulating layer.

The static friction coefficient of each of the insulating layers formed in the above examples and comparative examples was measured at 23° C. in accordance with JIS K7125:1999.
As a result, the static friction coefficients of the insulating layers in Examples 1 and 2 were 0.33 and 0.35, respectively, while the static friction coefficient of the insulating layer in Comparative Example 1 was 0.24. Therefore, the static friction coefficients of the insulating layers in Examples 1 and 2 were 1.35 times or more higher than that of the insulating layer in Comparative Example 1.

As can be seen from the above results, the present invention can provide a cylindrical member for an exhaust gas treatment device capable of increasing the frictional force against the outer peripheral surface of an electrically heated carrier, and an exhaust gas treatment device using this cylindrical member for an exhaust gas treatment device.The present invention can also provide an electrically heated member for an exhaust gas treatment device capable of increasing the frictional force against the inner peripheral surface of a cylindrical member, and an exhaust gas treatment device using this electrically heated member for an exhaust gas treatment device.

10 Cylindrical metal member 20 Insulating layer 21 Concave and convex portion 22 Concave portion 23 Convex portion 50 Honeycomb structure 51 Outer peripheral wall 52 First end face 53 Second end face 54 Cell 55 Partition wall 60 Electrode portion 100 Cylindrical member for exhaust gas treatment device 200 Electrically heated carrier 300 Electrically heated member for exhaust gas treatment device 500 Exhaust gas treatment device

Claims (14)

A cylindrical metal member;
an insulating layer provided on an inner circumferential surface of the cylindrical metal member,
the surface of the insulating layer has projections and recesses with a height difference of 300 μm or less and a static friction coefficient of 0.30 or more;
The insulating layer has a porosity of 10% or less and is a layer containing at least silicate glass or borosilicate glass. The cylindrical member for an exhaust gas treatment device according to claim 1, wherein the static friction coefficient is 0.35 or more. 3. The cylindrical member for an exhaust gas treatment device according to claim 1, wherein the ratio of projections and recesses on the surface of the insulating layer is 30% or more. 4. The cylindrical member for an exhaust gas treatment device according to claim 1 , wherein the arithmetic surface roughness Ra of the inner peripheral surface of the cylindrical metal member is 10 μm or less. 5. The cylindrical member for an exhaust gas treatment device according to claim 1, wherein a surface of the insulating layer has at least a groove-shaped concave portion or a substantially hemispherical convex portion. A columnar electrically heated carrier capable of heating exhaust gas;
An exhaust gas treatment device comprising: the cylindrical member for an exhaust gas treatment device according to any one of claims 1 to 5 , which houses the electrically heated carrier. The exhaust gas treatment device according to claim 6 , further comprising a mat material between the electrically heated carrier and the cylindrical member for the exhaust gas treatment device. A columnar electrically heated carrier capable of heating exhaust gas;
and an insulating layer provided on at least the outer circumferential surface of the electrically heated carrier;
the surface of the insulating layer has projections and recesses with a height difference of 300 μm or less and a static friction coefficient of 0.30 or more;
The electrically heated component for an exhaust gas treatment device, wherein the insulating layer has a porosity of 10% or less and is a layer containing at least silicate glass or borosilicate glass. 9. The electrically heated member for an exhaust gas treatment device according to claim 8 , wherein the static friction coefficient is 0.35 or more. 10. The electrically heated member for an exhaust gas treatment device according to claim 8, wherein the ratio of the irregularities on the surface of the insulating layer is 30% or more. The electrically heated member for an exhaust gas treatment device according to any one of claims 8 to 10 , wherein a surface of the insulating layer has at least a groove-shaped concave portion or a substantially hemispherical convex portion. An electrically heated member for an exhaust gas treatment device according to any one of claims 8 to 11 ,
and a cylindrical metal member that houses the electrically heated member for use in an exhaust gas treatment device. The exhaust gas treatment device according to claim 12 , further comprising a mat material between the electrically heated member for exhaust gas treatment device and the cylindrical metal member. The exhaust gas treatment device according to claim 12 or 13 , wherein the cylindrical metal member is the cylindrical member for an exhaust gas treatment device according to any one of claims 1 to 5 .

Images