JP5883321B2 - heater - Google Patents

Description

  The present invention relates to a heater. More particularly, the present invention relates to a heater that can be used to heat lubricating fluid such as engine oil and transmission fluid.

  Some machines operate while rubbing parts together. For example, in an internal combustion engine such as an engine, many parts rub against each other in the process of a piston moving up and down in a cylinder. If the parts rub against each other in this way, the parts may be worn or heated, and the machine may malfunction.

  Therefore, a lubricating fluid is used in order to reduce friction when parts rub against each other to suppress wear and heat generation. For example, engine oil is used as a lubricating fluid to suppress wear and heat generation of parts in the engine. Thus, in order to operate a machine that operates while rubbing parts together, a lubricating fluid is indispensable. However, when such a lubricating fluid is in a low temperature state, the viscosity of the lubricating fluid is increased. As a result, there arises a problem that the friction cannot be reduced sufficiently. Further, when the viscosity of the lubricating fluid becomes high, there also arises a problem that the lubricating fluid cannot be supplied to the target location.

  In order to cope with this problem, a lubricating fluid is heated using a heater. As a result, the viscosity of the lubricating fluid can be appropriately reduced, and the friction can be satisfactorily reduced by the lubricating fluid. However, if the lubricating fluid is excessively heated, there is a disadvantage that the lubricating fluid is deteriorated. Therefore, various heaters having a mechanism that does not excessively heat the lubricating fluid have been proposed (for example, Patent Documents 1 to 3).

JP 2003-74789 A JP 63-16114 A Japanese Utility Model Publication No. 63-12607

  However, with the conventional heater, it has been difficult to quickly raise the temperature of the lubricating fluid while keeping the mechanism that does not excessively heat the lubricating fluid effective. For example, Patent Document 1 describes a structure for preventing freezing of lubricating oil in which a heater is housed in a shell and the lubricating oil is indirectly heated. In the antifreezing structure described in Patent Document 1, the lubricating oil is indirectly heated. Therefore, the deterioration of the lubricating oil can be prevented. However, in the freeze prevention structure described in Patent Document 1, the heater is accommodated in the shell. For this reason, it is considered difficult to quickly raise the temperature of the lubricating oil.

  Patent Document 2 describes a heating device for engine oil in which a radiator fin that does not generate heat is attached to a heater. Patent Document 3 describes an oil heater in which a heat radiating member that does not generate heat is attached to the heater. As in Patent Document 2 and Patent Document 3, by attaching a heat radiating member or the like to the heater, the heat transfer area (heat exchange area) of the heater can be increased. However, the radiating fins and the radiating members attached to the heater do not generate heat by themselves. For this reason, it is considered difficult to quickly raise the temperature of the lubricating oil.

  In addition, in order to realize a rapid temperature increase, the size of the heater has to be increased. However, in an automobile or the like, there is a spatial restriction in the vehicle. For this reason, it has been difficult to use a large heater as a heating device for an engine. For this reason, development of a heater that is small and capable of quickly raising the temperature is desired.

  The present invention has been made in view of the above-described problems. An object of this invention is to provide the heater which can be used in order to heat lubrication system fluids, such as engine oil and a transmission fluid.

  In order to solve the above-described problems, the present invention provides the following heaters.

[1] A cylindrical honeycomb structure portion having partition walls that form a plurality of cells extending from one end face to the other end face that serve as a flow path for the lubricating fluid, and an outer peripheral wall that is positioned on the outermost periphery, and the honeycomb structure A pair of electrode parts joined to the side surface of the part via a conductive joint part, and the partition wall is made of a material whose main component is ceramics, and the entire honeycomb structure part generates heat when energized, and the electrode The shape of the part is such that the area of the joint part of the electrode part is smaller than the area of the shape surrounding the outer periphery of the electrode part, or the shape of the electrode part is rectangular and the corners are curved A heater for heating a lubricating fluid in which the ratio of the area of the joint portion of the electrode portion to the area of the shape that is formed and surrounds the outer periphery of the electrode portion is 40 to 95% .

[2] The conductive bonding material comprises a conductive paste containing a polyamide resin, an aliphatic amine and silver flakes, a silver compound, a conductive paste containing a silicate solution and water, a nickel powder and a silicate solution. The heater according to [1], which is one selected from the group consisting of a conductive paste containing, and a conductive paste containing aluminum oxide, graphite, and a silicate solution.

[ 3 ] The partition as described in [1] or [2] , wherein the partition has as a main component one selected from the group consisting of SiC, metal-impregnated SiC, metal composite SiC, and metal composite Si ₃ N ₄ . heater.

[ 4 ] The heater according to any one of [1] to [ 3 ], wherein the electrode portion has a plate shape in which a plurality of holes are formed.

[ 5 ] The heater according to any one of [1] to [ 3 ], wherein the shape of the electrode portion is a shape in which a plurality of strip-shaped electrode materials are arranged in a lattice pattern.

[ 6 ] The shape of the electrode part is a plate shape in which a protrusion is formed such that a surface on the honeycomb structure part side is recessed and a surface on the opposite side to the surface on the honeycomb structure part side protrudes. The heater according to any one of [1] to [ 3 ], wherein the ridges are formed in a plate shape on the plate-like electrode portion.

[ 7 ] The heater according to any one of [1] to [ 3 ], wherein the shape of the electrode portion is a comb-like shape having a plurality of strip-shaped partial electrodes.

[ 8 ] The heater according to any one of [1] to [ 3 ], wherein the electrode part has a rectangular shape with corners formed in a curved shape.

  As for the heater (1st heater) of this invention, an electroconductive joining part is "the electroconductive joining material was formed by baking at 60-200 degreeC." This is because when the conductive bonding material is fired at 60 to 200 ° C., the honeycomb structure portion and the pair of electrode portions are bonded via the conductive bonding material (the conductive bonding portion after baking). Means that. Therefore, the heater of the present invention has good heat generation performance due to energization. Furthermore, the heater of the present invention can prevent cracks from occurring in the honeycomb structure portion when the honeycomb structure portion mainly composed of ceramics and the electrode portion are joined. Furthermore, the heater of the present invention can prevent the electrode portion from peeling off from the honeycomb structure portion.

  In the heater of the present invention (first heater), the shape of the electrode portion is “the area of the joint portion of the electrode portion is smaller than the area of the shape surrounding the outer periphery of the electrode portion”. In the heater of the present invention, the shape of the electrode part may be a “rectangular shape with corners formed in a curved shape”. Therefore, the shape of the electrode part in the heater of the present invention is a shape in which thermal stress is reduced. Therefore, “after the electrode portion and the honeycomb structure portion are joined, cracks in the honeycomb structure portion or peeling of the electrode portion from the honeycomb structure portion” are suppressed. Furthermore, even under a use environment where heating and cooling are repeated, it is possible to prevent the electrode part from being peeled off from the honeycomb structure part or causing cracks in the honeycomb structure part.

  In the heater (second heater) of the present invention, the conductive joint portion is “containing a metal formed by thermal spraying, cold spraying, or plating”. Such a conductive joint portion functions as an “electrode” together with a pair of electrode portions. Moreover, such a conductive joint is formed directly on the surface of the honeycomb structure and has a low electric resistance. Therefore, a large current can be passed.

  In the heater of the present invention (second heater), the shape of the electrode portion is “the area of the joint portion of the electrode portion is smaller than the area of the shape surrounding the outer periphery of the electrode portion”. In the heater of the present invention, the shape of the electrode part may be a “rectangular shape with corners formed in a curved shape”. Therefore, the shape of the electrode part in the heater of the present invention is a shape in which thermal stress is reduced. Therefore, “after the electrode portion and the honeycomb structure portion are joined, cracks in the honeycomb structure portion or peeling of the electrode portion from the honeycomb structure portion” are suppressed. Furthermore, even under a use environment where heating and cooling are repeated, it is possible to prevent the electrode part from being peeled off from the honeycomb structure part or causing cracks in the honeycomb structure part.

It is a perspective view showing typically one embodiment of the heater of the present invention. It is a top view showing typically one embodiment of the heater of the present invention. It is a top view which shows typically the electrode part used for other embodiment of the heater of this invention. It is a top view which shows typically the electrode part used for other embodiment of the heater of this invention. It is a top view which shows typically the electrode part used for other embodiment of the heater of this invention. It is a schematic diagram which shows the A-A 'cross section in FIG. It is a top view which shows typically the electrode part used for other embodiment of the heater of this invention. It is a schematic diagram which shows the B-B 'cross section in FIG. It is a top view which shows typically that the "shape which surrounds the outer periphery of an electrode part" of an electrode part is a shape in which the corner | angular part was formed in the shape of a curve in a rectangle. It is a top view which shows typically that the "shape surrounding the outer periphery of an electrode part" of an electrode part is an octagon. It is a perspective view which shows typically other embodiment of the heater of this invention. It is a top view which shows typically the electrode part which comprises the heater of the comparative example 3. FIG. It is a perspective view which shows typically other embodiment of the heater of this invention. It is a perspective view which shows typically other embodiment of the heater of this invention.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. The present invention can be modified and improved based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

(1) Heater:
One embodiment of the heater (first heater) of the present invention includes a tubular honeycomb structure portion 4 and a pair of electrode portions 21 and 21 as shown in FIGS. 1 and 2. . The honeycomb structure portion 4 includes “a partition wall 1 that partitions and forms“ a plurality of cells 2 extending from one end surface 11 to the other end surface 12 serving as a flow path for the lubricating fluid ”, and an“ outer peripheral wall 3 positioned at the outermost periphery ”. ". The pair of electrode portions 21 and 21 are joined to the side surface 5 of the honeycomb structure portion 4 via the conductive joint portion 23. Further, in the heater 100 of the present embodiment, the partition wall 1 is made of a material mainly composed of ceramics and generates heat when energized. Furthermore, in the heater 100 of the present embodiment, the shape of the electrode portion 21 is a shape in which “the area of the joint portion of the electrode portion 21 is smaller than the area of the shape surrounding the outer periphery of the electrode portion 21”, or the electrode The shape of the portion 21 is a shape “a corner portion is formed in a curved shape in a rectangle”. Further, in the heater 100 of the present embodiment, the conductive bonding portion is “formed by baking the conductive bonding material at 60 to 200 ° C.”. Since the shape of the electrode part 21 in the heater 100 of this embodiment is the above shape, it is a shape in which thermal stress is reduced. FIG. 1 is a perspective view schematically showing one embodiment of the heater of the present invention. FIG. 2 is a plan view schematically showing one embodiment of the heater of the present invention.

  As described above, in the heater 100 of the present embodiment, the partition walls 1 of the honeycomb structure portion 4 are made of a material mainly composed of ceramics and generate heat when energized. Therefore, even if the size is small, it is possible to quickly raise the temperature of the lubricating fluid without excessively heating the lubricating fluid. Further, in the heater 100 of the present embodiment, the conductive bonding portion 23 is “formed by baking a conductive bonding material at 60 to 200 ° C.”. This is because when the conductive bonding material is fired at 60 to 200 ° C., the honeycomb structure portion and the pair of electrode portions are bonded via the conductive bonding material (the conductive bonding portion after baking). Means that. Therefore, the heater 100 of this embodiment has good heat generation performance due to energization. Furthermore, the heater 100 of the present embodiment can prevent the honeycomb structure portion 4 from being cracked when the honeycomb structure portion 4 mainly composed of ceramics and the electrode portion 21 are joined. Furthermore, the heater 100 of the present embodiment can prevent the electrode portion 21 from peeling off from the honeycomb structure portion 4. In the heater 100 of the present invention, the shape of the electrode portion 21 is “the area of the joint portion of the electrode portion is smaller than the area of the shape surrounding the outer periphery of the electrode portion”. In the heater 100 of the present invention, the shape of the electrode part may be a “rectangular shape with corners formed in a curved shape”. Therefore, the shape of the electrode part in the heater of the present invention is a shape in which thermal stress is reduced. Therefore, it is possible to prevent the electrode portion 21 from being peeled off from the honeycomb structure portion 4 after the electrode portion is joined to the honeycomb structure portion. Furthermore, it is possible to prevent cracks from occurring in the honeycomb structure portion after the electrode portion is joined to the honeycomb structure portion. Furthermore, even in a use environment where heating and cooling are repeated, it is possible to prevent the electrode portion 21 from being peeled off from the honeycomb structure portion 4 and cracking in the honeycomb structure portion.

  Here, the “shape in which thermal stress is reduced” is the shape of the electrode portion 21 that can reduce the thermal stress generated in the honeycomb structure portion 4 and the electrode portion 21 mainly composed of ceramics. “The shape of the electrode portion 21 is a shape in which the thermal stress is reduced”, so that the thermal stress received by the honeycomb structure portion 4 and the electrode portion 21 is reduced when the electrode portion 21 is joined to the honeycomb structure portion 4. Is done. In addition, the “shape surrounding the outer periphery of the electrode portion 21” is a shape in which the “circular shape circumscribing the electrode portion and having the shortest peripheral length (ring length)” is the outer peripheral shape. For example, in the case of the electrode part 21 arranged in the heater 100 shown in FIG. 1, as shown in FIG. 9, the outer peripheral shape of the electrode part is a rectangle and the corners are curved. For this reason, the “circular shape circumscribing the electrode portion and the shortest circumferential length (ring length)” (the shape 24 surrounding the outer periphery of the electrode portion) is a rectangular shape with curved corners. Shape. Further, when the shape of the electrode part is a lattice like the electrode part 21B shown in FIG. 4, the “shape 24 surrounding the outer periphery of the electrode part” has a rectangular corner as a straight line as shown in FIG. It is a shape formed by chamfering in a shape. The “shape formed by straightly chamfering the corners of the rectangle” is an octagon “the electrode portion 21B is inscribed”. Further, the “area of the joined portion of the electrode portion 21” is the area of the portion (region) of the electrode portion 21 joined to the side surface 5 of the honeycomb structure portion 4 via the conductive joined portion 23. That is. FIG. 9 is a plan view schematically showing that the “shape surrounding the outer periphery of the electrode portion” of the electrode portion 21 is a rectangle and corner portions are formed in a curved shape. FIG. 10 is a plan view schematically showing that the “shape surrounding the outer periphery of the electrode portion” of the electrode portion 21B is an octagon.

  Moreover, according to the heater 100 of this embodiment, the temperature of the lubricating fluid can be quickly raised without excessively heating the lubricating fluid. Moreover, even when the size of the heater 100 is small, the temperature of the lubricating fluid can be quickly raised. That is, in the heater 100 of the present embodiment, the partition wall 1 itself generates heat when energized. For this reason, the lubricating fluid can be continuously heated by the partition wall 1 in the course of the lubricating fluid flowing through the cell 2.

  For example, in a heater that heats the honeycomb structure portion with another heat source without causing the partition wall itself of the honeycomb structure portion to generate heat, it is difficult to heat the lubricating fluid well. That is, in the process of heating the lubricating fluid by the heater, heat exchange is performed between the lubricating fluid flowing in the cell and the partition wall. In a heater in which the partition wall itself does not generate heat, heating of the partition wall by another heat source cannot catch up, and it is difficult to quickly raise the temperature of the lubricating fluid. In addition, in a heater in which the partition wall itself does not generate heat, it is conceivable to increase another heat source to increase the heat transferred to the partition wall. However, such a method increases the size of the entire heater. In an automobile or the like, there is a spatial limitation in the vehicle, and it is difficult to use a large heater as a heating device for an engine.

  In addition, since the honeycomb structure portion 4 has a honeycomb structure having partition walls 1 that partition and form a plurality of cells 2, the contact area with the lubricating fluid can be increased. For this reason, the lubricating fluid flowing in the cell 2 can be satisfactorily heated. As a result, the temperature of the lubricating fluid can be quickly raised. That is, in the heater 100 of the present embodiment, the lubricating fluid that has flowed into the heater is divided into small portions, and the divided lubricating fluid flows in each cell 2. When the lubricating fluid is subdivided in this way, the contact area between the lubricating fluid and the partition wall 1 increases. Along with this, the amount of heat transfer due to the contact between the partition wall 1 and the lubricating fluid increases. Further, when the amount of heat transfer between the partition wall 1 and the lubricating fluid increases, the amount of heat transferred becomes larger than the amount of heat dissipated by thermal diffusion within the lubricating fluid. For this reason, the temperature of the lubricating fluid is likely to rise more rapidly.

  In the heater 100 of the present embodiment, the temperature of the lubricating fluid can be reliably increased even when the amount of heat generated per unit area of the partition wall 1 is reduced. This is because the heater 100 of the present embodiment can continue to heat the lubricating fluid in the flow path that circulates in the cell 2. If the calorific value per unit area of the partition wall 1 is reduced, it is possible to prevent the lubricating fluid from being heated excessively. Therefore, in the heater 100 of the present embodiment, the temperature of the lubricating fluid can be quickly raised without excessively heating the lubricating fluid. Further, since the lubricating fluid is not heated excessively in this way, deterioration of the lubricating fluid can be effectively suppressed.

  In this specification, “lubricating fluid” means a general term for fluids used for lubricating mechanical parts. Examples of the fluid used for lubricating the mechanical system parts include engine oil, transmission fluid, gear oil, differential oil, brake fluid, and power steering fluid.

  The heater of this embodiment can be used as a heater for heating a lubricating fluid such as an engine oil or transmission fluid of an automobile, for example. Generally, when an automobile is run in winter or is run in a cold region, the lubricating fluid tends to be low in temperature. If the lubricating fluid is in a low temperature state, its viscosity will increase. As a result, for the engine and transmission, the operation time increases while the friction generated in the parts is large. If the engine or transmission is operated in such a state, the fuel efficiency is deteriorated.

  If the heater of this embodiment is used, the temperature of engine oil or transmission fluid can be raised rapidly. As a result, the time during which the engine oil and transmission fluid are at a low temperature can be shortened. As a result, the fuel consumption of the automobile can be improved.

  In general, transmission fluid contributes more to the deterioration of fuel efficiency than engine oil. With conventional heaters, large heaters had to be used to sufficiently heat the transmission fluid. In the heater of the present embodiment, the transmission fluid can be sufficiently heated even when the heater is downsized. Thereby, the fuel consumption of a motor vehicle can be improved more. As described above, the heater according to the present embodiment exhibits its effect sufficiently when the space for installing the heater is limited, such as an automobile.

  Hereinafter, the heater of this embodiment is demonstrated in detail for every component.

(1-1) Electrode part:
A pair of electrode portions 21 disposed in the heater 100 shown in FIG. 1 are electrodes for energizing the partition walls 1 of the honeycomb structure portion 4. In the heater 100 of the present embodiment, the side surface 5 of the honeycomb structure portion 4 so that the one electrode portion 21 and the other electrode portion 21 of the pair of electrode portions 21 and 21 sandwich the honeycomb structure portion 4 from the side. It is arranged. By applying a voltage between the pair of electrode portions 21 and 21, the partition wall 1 is energized and the honeycomb structure portion 4 generates heat.

  In the electrode part 21, the part where the hole is opened is not joined to the side surface 5 of the honeycomb structure part 4. The joining portion of the electrode portion 21 is a portion that is in contact with the side surface 5 of the honeycomb structure portion 4 via the conductive joining portion, and is a portion excluding the hole portion. Therefore, the electrode portion 21 has a shape “the area of the joint portion of the electrode portion 21 is smaller than the area surrounding the outer periphery of the electrode portion 21” by the amount of the hole. And since the electrode part 21 is such a shape, a thermal stress is reduced. For example, the electrode part 21B shown in FIG. 4 is formed in a lattice shape. Therefore, the holes in the lattice shape and the “irregularities on the outer peripheral portion” are not joined to the side surface 5 of the honeycomb structure portion 4. Therefore, the electrode portion 21B has a shape in which “the area of the joint portion of the electrode portion 21 is smaller than the area of the shape surrounding the outer periphery of the electrode portion 21” by the amount of the formation of the holes and “unevenness of the outer peripheral portion”. It has become. And since the electrode part 21B is such a shape, a thermal stress is reduced.

  The heater 100 of the present embodiment includes a honeycomb structure portion 4 and a pair of electrode portions 21 and 21 joined to the side surface 5 of the honeycomb structure portion 4 via a conductive joint portion 23. The shape of the electrode portion 21 is a plate shape in which a plurality of holes are formed.

Examples of the material of the electrode part include stainless steel, nickel, copper, aluminum, molybdenum, tungsten, rhodium, cobalt, chromium, niobium, tantalum, gold, silver, platinum, palladium, and alloys of these metals. it can. Furthermore, these metal simple substance or alloy, and the composite material of ceramics, These metal simple substance or alloy, and the composite material of carbon etc. can be mentioned. Specifically, a composite material of copper and tungsten (Cu / W), a composite material of copper and molybdenum (Cu / Mo), a composite material of silver and tungsten (Ag / W), ceramics (for example, SiC, Al ₂ O ₃₎ ) And aluminum (SiC / Al, Al ₂ O ₃ / Al), ceramics (eg, SiC, Al ₂ O ₃ ) and copper (SiC / Cu, Al ₂ O ₃ / Cu), carbon And a composite material of copper and copper (C / Cu). At this time, it is desirable that the electrode portion has a low electrical resistance and a low thermal expansion coefficient. If the electrical resistance is high, a problem may occur due to heat generation of the electrode part itself during energization. The reason why the coefficient of thermal expansion is preferably small is as follows. That is, when the thermal expansion coefficient of the material of the electrode part is larger than that of the ceramic, the thermal stress generated when the electrode part is joined becomes large. For this reason, the interface between the electrode part and the honeycomb structure part may be peeled off or a crack may be generated in the honeycomb structure part. For this reason, it is further desirable that the thermal expansion coefficient of the electrode portion is close to that of ceramics. Further, when the electrode portion is made of the above composite material, the coefficient of thermal expansion is smaller than that of the metal only, and the difference in thermal expansion coefficient from the honeycomb structure portion mainly composed of ceramics is reduced. Therefore, if it consists of the said composite material, the thermal stress at the time of a thermal cycle can be reduced. Further, the surface of the electrode portion can be improved in adhesion after bonding by performing a surface roughening treatment. Examples of the surface roughening treatment include a treatment using sandblasting.

  100-3000 micrometers is preferable and, as for the thickness of an electrode part, 200-1000 micrometers is still more preferable. The preferable range of the thickness of the electrode part may vary depending on the material of the electrode part. If the thickness is less than 100 μm, a problem may occur due to resistance heating of the electrode section itself, or the bonding strength may be reduced. When the thickness is greater than 3000 μm, the thermal stress of the honeycomb structure part and the electrode part increases, and cracks may occur in the honeycomb structure part or the interface between the honeycomb structure part and the electrode part may peel off.

  In the heater 100 shown in FIG. 1, the ratio (joint portion area ratio) of the “area of the joined portion (joint surface) of the electrode portion” to the “area of the shape surrounding the outer periphery of the electrode portion” is 40 to 95%. It is preferable that This may vary depending on the material of the electrode part and the thickness of the electrode part. In order to reduce thermal stress, it is desirable to reduce the area of the joint portion (joint surface). However, if the area is too small, the energization performance of the heater (honeycomb structure) may be reduced. For this reason, it is preferable to take a balance so as to reduce the thermal stress and ensure the mechanical reliability of the electrode joint portion (joint portion of the electrode portion) without reducing the energization performance.

  In the heater 100 of the present embodiment, the terminal portion 22 is disposed on the electrode portion 21. The terminal portion 22 is a portion to which wiring from an external power source or the like is connected. The voltage is applied from an external power source or the like. The material of the terminal part may be the same as or different from the material of the electrode part. Further, the shape and size of the terminal portion 22 are not particularly limited. The shape and size of the terminal portion 22 can be appropriately determined according to the shape and size of the electrode portion 21 if resistance heating of the terminal portion itself does not cause a problem when energized.

  The shape of the electrode portion of the heater of the present invention is also preferably a shape in which a plurality of strip-shaped electrode materials 25 are arranged in a lattice pattern, as shown in FIG. The joining portion of the electrode portion 21 </ b> B is a portion where the band-shaped electrode material 25 is in contact with the side surface 5 of the honeycomb structure portion 4 via the conductive joining portion 23. Since the electrode portion 21B has such a shape, thermal stress is reduced. FIG. 4 is a plan view schematically showing an electrode portion 21B used in another embodiment of the heater of the present invention.

  In the electrode part 21B shown in FIG. 4, in order to reduce thermal stress, the area ratio (opening ratio) of the opening part (hole and recess in the outer peripheral part) formed by the electrode material 25 is approximately about 60%. Can be enlarged. The area ratio of the opening formed by the electrode material 25 is “a value obtained by subtracting the area of the joint portion of the electrode portion from the area of the shape surrounding the outer periphery of the electrode portion” with respect to “the area of the shape surrounding the outer periphery of the electrode portion”. Is the ratio. At this time, thermal stress can be reduced by reducing the width of the electrode material 25. However, if the electrode width (the width of the electrode material 25) is too small, there may be a problem due to the resistance heating of the local electrode part itself and the bonding strength of the electrode part. In addition, the preferable value of the said aperture ratio of the electrode part 21B may change with the materials and thickness of the electrode part 21B.

  As shown in FIG. 5 and FIG. 6, the shape of the electrode part of the heater of the present invention is “the surface 31 on the honeycomb structure part side is recessed and the“ surface 32 opposite to the surface on the honeycomb structure part side ”is It is also preferable that it is a plate shape in which the protruding ridges 33 are formed. In this case, it is preferable that the protrusions 33 are formed on the plate-like electrode portion 21C so as to be arranged in a lattice pattern. The joined portion of the electrode portion 21 </ b> C is a portion that is in contact with the side surface 5 of the honeycomb structure portion 4. In other words, it is a portion excluding the protrusions 33 “not in contact with the side surface 5 of the honeycomb structure portion 4 via the conductive joint portion 23” in the electrode portion 21 </ b> C. Since the electrode portion 21C has such a shape, thermal stress is reduced. FIG. 5 is a plan view schematically showing an electrode part 21C used in still another embodiment of the heater of the present invention. FIG. 6 is a schematic diagram showing a cross section taken along the line A-A ′ in FIG. 5.

  In the electrode portion 21 </ b> C shown in FIGS. 5 and 6, a non-contact portion that does not contact the honeycomb structure portion is formed by forming the ridge 33. The area ratio of the non-contact portion can be increased to about 60%. The area ratio of the non-contact portion is a ratio of “the area of the non-contact portion” to “the area of the shape surrounding the outer periphery of the electrode portion”. At this time, the thermal stress can be reduced by reducing the area of the joint portion of the electrode portion. However, if it is too small, the bonding strength of the electrode portion may be lowered, which is not desirable. The non-contact part is a part obtained by removing the joint part from the “shape surrounding the outer periphery of the electrode part”. The area ratio of the “non-contact portion” in the electrode portion 21 </ b> C is the ratio of the area of “the portion surrounding the outer periphery of the electrode portion to the portion excluding the bonding portion” with respect to “the area of the shape surrounding the outer periphery of the electrode portion”. Moreover, about the height H1 of the protruding item | line 33, since it is not a site | part directly related to a thermal stress, it is not specifically limited. Moreover, the preferable value of the said aperture ratio (area ratio of a "non-contact part") of the electrode part 21B may change with the materials and thickness of the electrode part 21B.

  The shape of the electrode part of the heater of the present invention is preferably a comb-like shape having a plurality of strip-shaped partial electrodes 34 as shown in FIGS. Since the electrode part 21D has such a shape, the thermal stress of the honeycomb structure part 4 and the electrode part 21D is reduced. FIG. 7 is a plan view schematically showing still another embodiment of the heater of the present invention. FIG. 8 is a schematic diagram showing a B-B ′ cross section of the electrode portion 21 </ b> D and the conductive joint portion 23 in FIG. 7.

  Further, as shown in FIG. 8, the partial electrode 34 is preferably curved so that a part thereof is convex outward. A portion of the partial electrode 34 that is curved so as to protrude outward is referred to as a curved portion 36. “To be convex outward” can also be “to protrude in a direction away from the honeycomb structure”. Thereby, the thermal stress of the honeycomb structure part and the electrode part 21D is further reduced.

  In the electrode portion 21D, in order to reduce thermal stress, the area ratio of “parts that do not contribute to bonding” can be increased to about 60%. The area ratio of the “part that does not contribute to bonding” in the electrode part 21D is the ratio of the area of “the part that excludes the bonding part from the shape that surrounds the outer periphery of the electrode part” to the “area of the shape that surrounds the outer periphery of the electrode part”. is there. At this time, the thermal stress can be reduced by reducing the area of the partial electrode 34, but if it is too small, the bonding strength of the electrode part may be lowered. The height H2 of the curved portion 36 is not particularly limited because it is not a portion directly related to thermal stress. Further, the preferred value of the area ratio of the partial electrode 34 (the area ratio of the “part not contributing to bonding”) may vary depending on the material and thickness of the partial electrode 34.

  In addition, as shown in FIG. 3, the shape of the electrode portion of the heater of the present invention is also preferably a shape “a corner portion 35 is formed in a curved shape in a rectangle”. Since the electrode portion 21A has such a shape, thermal stress is reduced. Further, it is more preferable that the shape of the electrode portion 21 </ b> A is a rectangle in which “the corner portion 35 is formed in an arc shape”. In this case, the radius of the arc of the corner 35 is preferably about 2 to 10 mm. In addition, in the electrode part 21 disposed in the heater 100 shown in FIG. 1, the electrode part 21C shown in FIG. 5, and the electrode part 21D shown in FIG. Thereby, the further thermal stress reduction effect can be acquired. FIG. 3 is a plan view schematically showing an electrode portion 21A used in still another embodiment of the heater of the present invention.

  As for the heater of this invention, as FIG. 11 shows, it is preferable that the terminal part 22 and the rod-shaped terminal part 26 are arrange | positioned at the electrode part 21. As shown in FIG. The rod-shaped terminal portion 26 is preferably electrically connected to the terminal portion 22. In this case, it is preferable that a wire from an external power source or the like is connected to the rod-shaped terminal portion 26. Further, when the heater of the present invention has the rod-shaped terminal portion 26, as shown in FIG. 11, the terminal portion 22 is disposed along the “side surface on which no electrode portion is disposed” of the honeycomb structure portion. It is preferable.

  In the heater 100 of the present embodiment shown in FIGS. 1 and 2, a pair of electrode portions 21 and 21 are joined to the side surface 5 of the honeycomb structure portion 4 via a conductive joint portion 23. The conductive bonding portion 23 is formed by baking a conductive bonding material at 60 to 200 ° C. This is because when the conductive bonding material is fired at 60 to 200 ° C., the honeycomb structure portion 4 and the pair of electrode portions 21 and 21 become the conductive bonding material (the conductive bonding portion 23 after firing). It means that it is joined. In this specification, “sintering” an object to be fired (for example, a conductive bonding material) means melting a part of the object to be fired by heating and bonding the components of the object to be fired. This means that the product is a fired product (for example, a conductive joint). When the conductive bonding material is fired to become a conductive bonding portion that is a fired product, the honeycomb structure portion and the electrode portion are bonded via the conductive bonding portion.

  Here, the conductive paste containing “polyamide resin, aliphatic amine and silver flake” is referred to as conductive paste A. Also, a conductive paste containing “silver compound, silicate solution and water” is referred to as conductive paste B. A conductive paste containing “nickel powder and silicate solution” is referred to as conductive paste C. Here, it is preferable that 30-60 mass% of nickel powder is contained with respect to the whole conductive paste C. Further, a conductive paste containing “aluminum oxide, graphite and silicate solution” is referred to as a conductive paste D. In this case, the conductive bonding material is preferably one selected from the group consisting of conductive paste A, conductive paste B, conductive paste C, and conductive paste D. Therefore, it is preferable that the conductive bonding portion 23 is obtained by firing one selected from the group consisting of the conductive paste A, the conductive paste B, the conductive paste C, and the conductive paste D. By making the material of the conductive joint portion 23 as described above, the heater of the present embodiment has good heat generation performance due to energization. Furthermore, the heater of this embodiment has a bonding temperature lower than that of general solder bonding. That is, the bonding temperature is 200 ° C. or lower. Therefore, since thermal stress is reduced, it is possible to prevent cracks from occurring in the honeycomb structure portion when the honeycomb structure portion mainly composed of ceramics and the electrode portion are joined. Furthermore, the heater according to the present embodiment can prevent the electrode portion from peeling off from the honeycomb structure portion.

(1-2) Honeycomb structure part:
As shown in FIG. 1 and FIG. 2, the honeycomb structure portion 4 includes “a partition wall 1 that partitions and forms a plurality of cells 2 extending from one end face 11 to the other end face 12 that serve as a flow path for the lubricating fluid”, and It has “the outer peripheral wall 3 located in the outermost periphery”.

  The partition wall 1 is made of a material mainly composed of ceramics. Further, the partition wall 1 preferably has a ceramic content of 90% by mass or more, and more preferably has a ceramic content of 99% by mass or more. Here, in the present specification, “having ceramics as a main component” means containing 50% by mass or more of ceramics. That is, the partition wall made of a material mainly composed of ceramics means a partition wall containing 50% by mass or more of ceramics.

  In the heater of this embodiment, it is preferable that the specific resistance of the partition wall is 0.01 to 50 Ω · cm. In the heater of the present embodiment, the specific resistance of the partition wall is more preferably 0.03 to 10 Ω · cm, and particularly preferably 0.07 to 5 Ω · cm. By setting the specific resistance of the partition wall within the above numerical range, a heater capable of quickly raising the temperature of a lubricating fluid such as engine oil or transmission fluid can be obtained. In addition, the honeycomb structure can be sufficiently reduced in size.

In the heater of this embodiment, the partition wall 1 generates heat when energized. The partition wall 1 is preferably composed mainly of one selected from the group consisting of SiC, metal-impregnated SiC, metal composite SiC, and metal composite Si ₃ N ₄ . These components are “ceramics that generate heat when energized”.

  SiC includes recrystallized SiC and reaction sintered SiC. The recrystallized SiC is produced as follows, for example. First, a raw material containing SiC powder, an organic binder, and “water or an organic solvent” is mixed and kneaded to prepare a clay. Next, this clay is molded to produce a molded body. Next, the obtained molded body is fired at 1600 to 2300 ° C. in an inert gas atmosphere to obtain a fired body. What is obtained in this way is “recrystallized SiC”. And the obtained sintered body becomes mainly porous. Recrystallized SiC can change the specific resistance by changing the raw material, particle size, impurity amount, and the like. For example, the specific resistance can be changed by dissolving impurities in SiC. Specifically, by firing in a nitrogen atmosphere, nitrogen can be dissolved in SiC to reduce the specific resistance of recrystallized SiC.

  Reaction-sintered SiC is SiC generated by utilizing a reaction between raw materials. Examples of the reaction-sintered SiC include porous reaction-sintered SiC and dense reaction-sintered SiC. The porous reaction-sintered SiC is produced, for example, as follows. First, a clay is prepared by mixing and kneading silicon nitride powder, carbonaceous material, silicon carbide and graphite powder. The carbonaceous substance is a substance that reduces silicon nitride. Examples of the carbonaceous material include solid carbon powders such as carbon black and acetylene black, resins such as phenol, furan, and polyimide. Next, this clay is molded to produce a molded body. Next, the molded body is primarily fired in a non-oxidizing atmosphere to obtain a primary fired body. Next, the obtained primary fired body is heated in an oxidizing atmosphere and decarburized to remove the remaining graphite. Next, the “decarburized primary fired body” is secondarily fired at 1600 to 2500 ° C. in a non-oxidizing atmosphere to obtain a secondary fired body. What is obtained in this way is “porous reaction sintered SiC”.

  Dense reaction-sintered SiC is produced, for example, as follows. First, SiC powder and graphite powder are mixed and kneaded to prepare a clay. Next, this clay is molded to produce a molded body. Next, this molded body is impregnated with “molten silicon (Si)”. Thereby, the carbon which comprises graphite and the silicon | silicone impregnated are made to react, and SiC is produced | generated. As described above, pores are easily eliminated by “impregnating” the molten body with “molten silicon (Si)”. That is, the pores are easily blocked. Therefore, a dense molded body can be obtained. The product thus obtained is “dense reaction sintered SiC”.

  Examples of “metal-impregnated SiC” include Si-impregnated SiC, SiC impregnated with metal Si and other types of metals, and the like. Examples of the “other types of metals” include Al, Ni, Cu, Ag, Be, Mg, and Ti. When the partition wall is made of the above-described material having “metal-impregnated SiC” as a main component, the partition wall has excellent heat resistance, thermal shock resistance, oxidation resistance, thermal conductivity, and corrosion resistance. “Corrosion resistance” means resistance to the corrosive action caused by acid or alkali.

  Examples of the metal-impregnated SiC include a porous body mainly composed of SiC particles impregnated with a molten metal. For this reason, the metal-impregnated SiC can be a dense body having relatively few pores.

  “Si-impregnated SiC” is a concept generically referring to a sintered body containing metal Si and SiC as constituent components. Metal Si means metal silicon. In Si-impregnated SiC, the surface of the SiC particles is surrounded by solidified metal Si. Accordingly, the Si-impregnated SiC has a structure in which a plurality of SiC particles are bonded to each other through metal Si.

  “SiC impregnated with metal Si and other types of metals” is a concept generically referring to sintered bodies containing metal Si, other types of metals, and SiC as constituent components. In SiC impregnated with metal Si and other types of metals, the surface of the SiC particles is surrounded by solidified products of metal Si and other types of metals. Thereby, SiC impregnated with metal Si and other types of metals has a structure in which a plurality of SiC particles are bonded to each other via metal Si and other types of metals.

  When the partition wall is made of a material mainly composed of metal-impregnated SiC, generally, the specific resistance of the partition wall becomes smaller as the amount of metal to be impregnated increases.

  Examples of the above-mentioned “metal composite SiC” include Si composite SiC, SiC obtained by composite sintering of metal Si and other types of metals, and the like. Examples of the “other types of metals” include Al, Ni, Cu, Ag, Be, Mg, and Ti.

  Examples of the metal composite SiC include those obtained by mixing and sintering SiC particles and metal powder. When the SiC particles and the metal powder are mixed and sintered, the sintering proceeds at the contact point between the SiC particles and the metal powder. For this reason, metal composite SiC can be made into the porous body in which comparatively many pores were formed. In the metal composite SiC, pores of a porous body are formed while taking a structure in which SiC particles are interconnected via a metal phase made of metal powder. For example, Si composite SiC has a structure in which SiC particles are bonded to each other through metal Si while forming pores in a form in which a metal Si phase is bonded to the surface of SiC particles. Also in SiC in which metal Si and other types of metals are combined and sintered, the same structure as that of the metal composite SiC is taken.

  When the partition is made of a material mainly composed of metal composite SiC, generally, the specific resistance of the partition becomes smaller as the amount of metal to be combined increases.

  In the heater of the present embodiment, the amount of heat generated per unit surface area of the partition wall depends on the size of the honeycomb structure, the specific resistance of the partition wall, the partition wall thickness, the cell density, and the like. For example, when the size of the honeycomb structure portion is limited, the amount of heat generated per unit surface area of the partition wall can be adjusted by adjusting the partition wall thickness and cell density. Thereby, it can be set as the heater which does not heat a lubrication system fluid excessively. In addition, when there is a sufficient space for the heater, the size of the honeycomb structure can be adjusted to adjust the amount of heat generated by the heater. The size of the honeycomb structure part means the length in the cell extending direction of the honeycomb structure part or the size of the cross section orthogonal to the cell extending direction of the honeycomb structure part. Hereinafter, “the length of the honeycomb structure portion in the cell extending direction” may be simply referred to as “the length of the honeycomb structure portion”. Further, “the size of the cross section perpendicular to the cell extending direction of the honeycomb structure portion” may be simply referred to as “the size of the cross section of the honeycomb structure portion”.

  For example, when the length of the honeycomb structure portion can be increased, the distance for heating the lubricating fluid can be increased. Thereby, a lubrication system fluid can be heated favorably. Further, if the lubricating fluid can be sufficiently heated by increasing the length of the honeycomb structure portion, the specific resistance of the partition walls may be relatively reduced.

  On the other hand, when the length of the honeycomb structure part and the size of the cross section of the honeycomb structure part are limited, it is preferable to adjust the heat generation amount per unit surface area of the partition walls. In that case, it is preferable to adjust the calorific value per unit surface area of the partition by adjusting the specific resistance of the partition, the thickness of the partition, the cell density, and the like.

  For example, the specific resistance of the partition wall can be adjusted by adjusting the porosity of the partition wall. In general, the smaller the porosity of the partition wall, the smaller the specific resistance of the partition wall.

  Moreover, the preferable range of the porosity of a partition changes with main components of a partition. For example, when metal composite SiC is the main component, the porosity of the partition walls is preferably 30 to 90%. Moreover, when metal composite SiC is a main component, many open pores exist in the partition wall, and the pores become large. And the partition which has metal composite SiC as a main component has many communicating vents which connect between adjacent cells. For this reason, this continuous vent allows the lubricating fluid to pass through the partition wall. Accordingly, the contact area between the partition wall and the lubricating fluid increases. Therefore, a heater including a honeycomb structure having partition walls mainly composed of metal composite SiC has improved heating efficiency (that is, heat exchange efficiency). On the other hand, for example, when metal-impregnated SiC is the main component, the porosity of the partition walls is preferably 0 to 10%. Further, when the metal-impregnated SiC is a main component, the pores of the partition walls are reduced and the open pores are reduced. Therefore, it is difficult for the lubricating fluid to enter the partition wall mainly composed of metal-impregnated SiC. Therefore, the lubricating system fluid that remains in the pores of the partition wall and stops flowing is reduced. Therefore, it is possible to prevent the lubricating fluid from being overheated and deteriorated. Further, since there are no pores communicating between the cells, the lubricating fluid does not pass through the partition walls. Therefore, only the lubricating system fluid can flow in the cell.

  Moreover, the specific resistance of a partition can be adjusted also with the kind of SiC used for a partition. Examples of SiC include α-SiC and β-SiC. In addition, the specific resistance of the partition walls can be adjusted by adjusting the mixing ratio of α-SiC or β-SiC. Furthermore, the specific resistance of the partition wall can be adjusted by the purity (impurity amount) of SiC.

  Further, the specific resistance of the partition changes depending on the amount of impurities in the metal used for the partition. Moreover, an alloy can also be used as a metal. In addition, the metal can be alloyed when the honeycomb structure is manufactured. By doing in this way, the specific resistance of a partition can be changed.

In the heater of this embodiment, it is preferable that the partition wall thickness of the honeycomb structure portion is 0.1 to 0.51 mm. Moreover, it is preferable that the cell density of a honeycomb structure part is 15-280 cells / cm < ² >. By using the honeycomb structure configured as described above, the temperature of the lubricating fluid can be quickly increased without excessively heating the lubricating fluid. In the heater of the present embodiment, it is more preferable that the partition wall thickness is 0.1 to 0.51 mm, and the cell density of the honeycomb structure portion is 15 to 280 cells / cm ² .

In the heater of the present embodiment, it is more preferable that the partition wall thickness of the honeycomb structure portion is 0.25 to 0.51 mm, and the cell density of the honeycomb structure portion is 15 to 62 cells / cm ^2. . Moreover, it is especially preferable that the thickness of the partition wall is 0.30 to 0.38 mm and the cell density is 23 to 54 cells / cm ² . Thereby, the pressure loss at the time of lubricating system fluid distribute | circulating the inside of a cell can be made small.

  The shape of the honeycomb structure is not particularly limited. For example, the end surface is a cylindrical tube (cylindrical shape), the end surface is an oval tube, the end surface is a polygon (square, pentagon, hexagon, heptagon, octagon, etc. ) Or the like. The shape of the honeycomb structure portion 4 shown in FIG. 1 is a cylindrical shape having a square end face.

  An outer peripheral wall is a wall which comprises the side surface of a honeycomb structure part. The outer peripheral wall may be formed together with the partition walls in the process of manufacturing the honeycomb structure portion. For example, the partition wall and the outer peripheral wall may be produced by extrusion molding at a time. Further, it is not necessary to form the outer peripheral wall at the time of extrusion molding. For example, the outer peripheral wall can be formed by coating a ceramic material on the outer peripheral portion of the partition wall that defines the cell.

The outer peripheral wall 3 is preferably made of a material mainly composed of ceramics. The outer peripheral wall 3 further preferably contains 90% by mass or more of ceramics, and particularly preferably contains 99% by mass or more of ceramics. Examples of the material (ceramics) of the outer peripheral wall 3 include SiC, metal-impregnated SiC, metal composite SiC, and metal composite Si ₃ N ₄ . The partition wall and the outer peripheral wall may be made of the same material, or may be made of different materials. The specific resistance of the outer peripheral wall is preferably 0.01 to 50 Ω · cm, similarly to the specific resistance of the partition walls. In the heater of this embodiment, the specific resistance of the outer peripheral wall is more preferably 0.03 to 10 Ω · cm, and particularly preferably 0.07 to 5 Ω · cm. The reason is the same as in the case of the partition wall.

  More preferably, the outer peripheral wall is thick. That the outer peripheral wall is thick means that the outer peripheral wall is thicker than the partition wall. When the outer peripheral wall is thick, the strength of the outer peripheral wall as a structure increases. For this reason, it is possible to improve resistance to thermal stress during electrode bonding. As a result, it becomes easy to suppress the generation of cracks in the outer peripheral wall. Further, if the outer peripheral wall is thick, the heat capacity of the outer peripheral wall increases. Therefore, the temperature rise of the outer peripheral wall during energization can be reduced. Here, the outer peripheral wall tends to overheat because the contact area with the lubricating fluid such as engine oil is small. Therefore, as described above, it is preferable to reduce the temperature rise of the outer peripheral wall during energization. In addition, when a resin is used in at least a part of the heater housing, the resin may deteriorate and be damaged due to local overheating of the heater. Therefore, it is possible to suppress damage due to deterioration of the resin by making the outer peripheral wall of the honeycomb structure portion thick.

  Although the thickness of an outer peripheral wall is based also on the porosity of an outer peripheral wall, etc., 0.3-5 mm is preferable and 0.5-3 mm is still more preferable.

  The outer peripheral wall is more preferably dense. When the outer peripheral wall is dense, it is possible to prevent the lubricating fluid from leaking out of the heater through the inside of the outer peripheral wall. Here, normally, when the heater is accommodated in the housing, a sealing material is disposed on the outer periphery of the heater in order to prevent the lubricating fluid from leaking into the housing. If the outer peripheral wall is made dense, it is possible to prevent the lubricating fluid from leaking out of the heater as described above, and thus the sealing material becomes unnecessary.

The “dense outer peripheral wall” is preferably one that has been densified by impregnation with metal, for example. The “dense outer peripheral wall” may be formed of dense “Al ₂ O ₃ , MgO, SiO ₂ , Si ₃ N ₄ , AlN, or BN” or a composite thereof.

  A honeycomb structure having such a “dense outer peripheral wall” includes, for example, a “material constituting the partition wall” and a different type of “material constituting the outer wall” from this “material constituting the partition wall”. It can produce by extruding.

In addition, the honeycomb structure portion having “the outer peripheral wall densified by being impregnated with metal” is preferably formed by impregnating metal into a dried honeycomb formed body or a fired honeycomb sintered body. Note that Si is preferable as the metal to be impregnated. In order to impregnate the dried honeycomb formed body or the fired honeycomb sintered body with metal, the amount of metal to be impregnated (for example, Si amount) is adjusted so that only the outer peripheral wall is impregnated. There is a method of impregnating metal. Alternatively, there is a method in which an impregnation inhibiting material is coated on both end faces of the honeycomb formed body after drying or honeycomb sintering after firing, or a plate-like jig is placed on both end faces. By these methods, the outer peripheral wall can be preferentially impregnated with metal. Examples of the impregnation inhibitor include oxides, particularly Al ₂ O ₃ .

  The heater of the present invention has an insulating layer having a dielectric breakdown strength of 10 to 1000 V / μm on the surface of a partition wall that partitions and forms a plurality of cells extending from one end face to the other end face that serve as a flow path for the lubricating fluid. It is preferable. The dielectric breakdown strength of the insulating layer is more preferably 100 to 1000 V / μm. Lubricating fluids may contain metallic wear powder or moisture generated from parts. In particular, most of the metallic wear powder is removed by an oil filter or the like, but there are some that remain in the lubricating fluid without being removed. For this reason, when the heater is used for a long period of time, the metallic wear powder remaining without being removed may adhere to the partition walls or accumulate and become clogged. In such a case, the heater may be short-circuited. When an insulating layer having a dielectric breakdown strength of 10 to 1000 V / μm is provided on the surface of the partition walls of the honeycomb structure portion, metallic wear powder contained in the lubricating fluid adheres to and accumulates on the partition walls and clogs. Thus, the heater can be prevented from being short-circuited.

  An example of the insulating layer is an oxide film formed by oxidizing a ceramic component contained in a partition wall. Such an oxide film can be formed by high-temperature treatment in an oxidizing atmosphere.

  Alternatively, the insulating layer can be provided by coating the surface of the partition wall with an insulating resin. In the heater of the present invention, when the insulating layer on the surface of the partition wall is made of an insulating resin, as the insulating resin, generally used resins such as EPDM, ethylene propylene copolymer, polyimide, polyamideimide, etc. Can be used.

As the insulating layer, a ceramic coating layer, a SiO ₂ glass coating layer, or a coating layer of a mixture of ceramic and “SiO ₂ glass” can be provided.

Examples of the ceramic coating layer include a layer mainly composed of oxides such as Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , and CeO ₂ and a layer mainly composed of nitride. Among the oxide-based component and the nitride-based component, the oxide-based component is more stable in the atmosphere. On the other hand, those containing nitride as a main component are more excellent in heat conduction. Examples of the SiO ₂ -based glass coat layer include those containing SiO ₂ as a main component. As a coating layer of a mixture of ceramic and SiO ₂ -based glass, a layer mainly composed of a mixture of SiO ₂ and “components such as Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , and CeO ₂ ” can be cited. be able to. In addition, the structural component of an insulating layer can be suitably selected according to the required value of withstand voltage.

A wet method or a dry method can be employed to form the ceramic coat layer, the SiO ₂ glass coat layer, and the coat layer of the mixture of ceramic and SiO ₂ glass, respectively.

  As a wet method, the honeycomb structure is immersed in any one of the insulating layer forming slurry, the insulating layer forming colloid, and the insulating layer forming solution, and then the excess is removed, dried, and fired. The method of doing can be mentioned.

For example, when forming an “insulating layer mainly composed of oxide”, the insulating layer forming slurry and the insulating layer forming colloid include a metal source such as Al, Mg, Si, Zr, Ti, Ce, or the like Those containing an oxide can be used. The “insulating layer mainly composed of oxide” is an insulating layer mainly composed of Al ₂ O ₃ , MgO, SiO ₂ , ZrO ₂ , TiO ₂ , CeO ₂ or the like. As the insulating layer forming solution, a metal alkoxide solution such as Al (OC ₃ H ₇ ) ₃ , Si (OC ₂ H ₅ ) ₄ can be used. The sintering temperature in the wet method can be appropriately determined depending on the main component. The sintering temperature in the wet method is preferably 1100 to 1200 ° C., for example, in the case of an insulating layer mainly composed of SiO ₂ . In the case of an insulating layer mainly composed of Al ₂ O ₃ , the temperature is preferably 1300 to 1400 ° C.

When forming the “insulating layer mainly composed of nitride”, the honeycomb structure is immersed in one of the insulating layer forming slurry, the insulating layer forming colloid, and the insulating layer forming solution, and then the excess Remove and dry. Thereafter, nitriding is performed in a reducing atmosphere containing nitrogen or ammonia. In this manner, an insulating layer containing nitride as a main component can be formed. Examples of the nitride include AlN, Si ₃ N _{4, and the} like that have insulating properties and high thermal conductivity.

  Examples of the dry method include an electrostatic spray method. For example, the insulating layer can be formed by electrostatic spraying as follows. First, a voltage is applied to an insulating substance powder (insulating particles) or “slurry containing insulating particles” to be negatively (or positively) charged. Thereafter, the charged “insulating particles or slurry containing insulating particles” is sprayed onto the positively (or negatively) honeycomb structure. In this way, an insulating layer is formed.

  The film thickness of the insulating layer can be appropriately set according to the desired withstand voltage. When the thickness of the insulating layer is thick, the thermal resistance increases to heat the lubricating fluid, although the insulating property increases. This is because the insulating layer tends to have lower thermal conductivity than the partition. Furthermore, the pressure loss of the heater increases. Therefore, it is preferable that the thickness of the insulating layer is as thin as possible within a range where the insulating property can be secured. Specifically, the thickness of the insulating layer is preferably smaller than the thickness of the partition wall. More specifically, although it depends on the dielectric breakdown strength for each material, it is preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 3 μm or less. When the film thickness of the insulating layer is in the above range, it is possible to prevent an increase in pressure loss in the honeycomb structure portion while maintaining a low thermal resistance. The film thickness of an insulating layer means the average film thickness of an insulating layer. The film thickness of the insulating layer is a value measured by observing with an optical microscope or an electron microscope using a cross-sectional sample. Here, the “cross-section sample” is a sample obtained by cutting out a part of the heater, and is a sample having a cut surface perpendicular to the wall surface of the partition wall. For example, when the insulating layer is an oxide film, the firing temperature is preferably set to 1200 to 1400 ° C. in order to form the oxide film having the above thickness. It is also a preferable method to form an oxide film by baking in a water vapor atmosphere. Furthermore, the film thickness of the oxide film can be adjusted by adjusting the baking time. The longer the firing time, the thicker the oxide film.

  Each of the pair of electrode portions 21 is preferably formed in a strip shape extending in the extending direction of the cells 2 of the honeycomb structure portion 4. In addition, in the cross section orthogonal to the extending direction of the cells 2, it is preferable that one electrode portion 21 is disposed on the opposite side of the other electrode portion 21 with the center of the honeycomb structure portion 4 interposed therebetween. In FIG. 1, the electrode portions 21 and 21 are disposed on “two parallel (parallel) side surfaces” of the honeycomb structure portion 4 whose end surface is a quadrangular cylindrical shape. By comprising in this way, the bias | inclination of the temperature distribution of the honeycomb structure part 4 when a voltage is applied between a pair of electrode parts 21 and 21 can be suppressed.

(2) Heater manufacturing method:
Next, the manufacturing method of one embodiment (refer FIG. 1) of the heater of this invention is demonstrated.

  When a honeycomb structure having Si composite SiC (ceramics) as a main component is manufactured, first, SiC powder, metal Si powder, water, an organic binder, and the like are mixed and kneaded to prepare a clay. Then, this clay is formed into a honeycomb shape to produce a honeycomb formed body. Thereafter, the obtained honeycomb molded body is fired in an inert gas atmosphere, whereby a honeycomb structure part mainly composed of Si-impregnated SiC can be manufactured. When producing a honeycomb structure mainly composed of Si-impregnated SiC, first, SiC powder, metal Si powder, water, an organic binder, and the like are mixed and kneaded to prepare a clay. Moreover, SiC powder, water, an organic binder, etc. may be mixed and kneaded to prepare a clay. Then, this clay is formed into a honeycomb shape to produce a honeycomb formed body. Thereafter, the resulting honeycomb formed body is fired in an inert gas atmosphere to form a honeycomb structure. Thereafter, the obtained honeycomb structure is impregnated with Si in an inert gas atmosphere, whereby a honeycomb structure part mainly composed of Si-impregnated SiC can be manufactured. The production of recrystallized SiC and reaction-sintered SiC is as described above.

As the ceramic material constituting the outer peripheral wall and partition walls, silicon _{carbide, Fe-16Cr-8Al, SrTiO} 3 (perovslite), Fe 2 O 3 (corundum), SnO 3 (rutile), cited ZnO (wurzite) etc. be able to. These materials are materials having a specific resistance of 0.01 to 50 Ω · cm. Specific resistivity of each material is as follows. The specific resistance of silicon carbide generally has a wide width of 1 to 1000 Ω · cm, and if SiC is used alone, it is preferably within the specific resistance range described above. In the case of compounding with Si and an Si-based alloy, it is possible to apply up to a maximum of 1000 Ω · cm depending on the microstructure. The specific resistance of Fe-16Cr-8Al is about 0.03 Ω · cm. The specific resistance of SrTiO ₃ (perovslite) is 0.1 Ω · cm or less. The specific resistance of Fe ₂ O ₃ (corundum) is about 10 Ω · cm. The specific resistance of SnO ₃ (rutile) is 0.1 Ω · cm or less. The specific resistance of ZnO (wurzite) is 0.1 Ω · cm or less.

  Here, the honeycomb structure portion preferably has a value of “metal Si content / (Si content + SiC content)” of 5 to 50. The honeycomb structure portion further preferably has a value of “metal Si content / (Si content + SiC content)” of 10 to 40. Thereby, specific resistance can be made into a suitable magnitude | size, maintaining the intensity | strength of an outer peripheral wall or a partition.

Furthermore, in the heater 100 of this embodiment, it is preferable that a SiO ₂ film (oxide film) formed by oxidizing SiC is formed as an insulating film on the surface of the partition wall. When forming the oxide film on the surface of the partition wall, it is preferable to perform high temperature treatment in an oxidizing atmosphere such as air. In the case where the main component of the partition walls is SiC, Si-impregnated SiC, or Si composite SiC, for example, the treatment is preferably performed in the atmosphere at 1200 ° C. for 6 hours. Thereby, an oxide film can be formed on the surface of the partition wall.

  Next, in order to form an electrode, it is preferable to remove the oxide film layer from the side surface of the honeycomb structure portion by machining. Thereby, it is preferable to expose the Si—SiC layer on the side surface of the honeycomb structure portion. Side surfaces from which the oxide film layer is removed in the honeycomb structure portion are two side surfaces on which the electrode portions are disposed. And after exposing the Si-SiC layer which has electroconductivity, it is preferable to apply | coat an electroconductive joining material to the said 2 side surface.

  Similarly to the above, a conductive paste containing “polyamide resin, aliphatic amine and silver flakes” is referred to as a conductive paste A. Also, a conductive paste containing “silver compound, silicate solution and water” is referred to as conductive paste B. A conductive paste containing “nickel powder and silicate solution” is referred to as conductive paste C. Here, it is preferable that 30-60 mass% of nickel powder is contained with respect to the whole conductive paste C. Further, a conductive paste containing “aluminum oxide, graphite and silicate solution” is referred to as a conductive paste D. In this case, the conductive bonding material is preferably one selected from the group consisting of conductive paste A, conductive paste B, conductive paste C, and conductive paste D. The heater of this embodiment obtained by joining an electrode part and a honeycomb structure part using such a conductive joining material has good heat generation performance by energization. Further, the obtained heater of the present embodiment is less susceptible to cracks in the honeycomb structure mainly composed of ceramics because thermal stress is reduced. Furthermore, in the heater of the present embodiment obtained, the electrode part is difficult to peel off from the honeycomb structure part.

  Conventionally, Al solder, Ag solder, Au solder, Pd solder, Ni solder, Cu solder, Pb free solder, In solder, and the like generally exist as a joining material for joining ceramics and metal. Among these, for example, when a general-purpose Ag solder (or AgCuTi active metal solder) is used for ceramic bonding, it is necessary to raise the temperature to about 850 ° C. as described in JP-A-63-190773. It was. However, in the manufacture of the heater of the present invention, when the electrode part is joined to the honeycomb structure part, when the temperature is raised to a high temperature of 850 ° C., the honeycomb structure part is cracked when cooled, There was a problem that the part easily peeled off. In addition, about 600 ° C. is required as the bonding temperature for Al brazing or the like. Therefore, there is a problem that the probability of occurrence of cracks increases due to the residual stress during bonding. In addition, with Pb-free solder, bonding at about 200 ° C. is possible. However, when joining with ceramics, surface treatment (metallization) was required to obtain wettability. On the other hand, by using a conductive bonding material as used in the manufacture of the heater of the present invention, the electrode portion is formed on the honeycomb structure portion by firing at a low temperature of 200 ° C. or less without performing surface treatment (metallization). It is possible to join. Furthermore, the heater obtained by joining the electrode part and the honeycomb structure part by firing a conductive bonding material interposed between them has a heat resistance higher than a firing temperature of 200 ° C. or less. Sex can be maintained. In particular, the heating target of the heater of the present invention is a lubricating fluid. Therefore, it is preferable not to raise the temperature excessively in order to prevent problems such as deterioration of the lubricating fluid. Note that a lubricating fluid to be heated flows inside the honeycomb structure, and the lubricating fluid receives heat from the heater. In other words, the lubricating fluid will remove heat from the heater. Therefore, the lubricating fluid acts as a coolant for the heater. As a result, even if the heater generates heat to a high temperature, the actual temperature at the conductive joint outside the heater tends to be low. From the above, since the heat resistance for the joint portion is about 200 to 250 ° C., there is no problem, so in the present invention, the conductive bonding material is selected from various bonding materials. Then, in order to produce a “heater having excellent heater characteristics and high reliability after joining and after a thermal cycle”, a structure for reducing thermal stress is studied, and the present invention is reached.

  Next, an electrode part is affixed on the conductive bonding material. Thereby, it will be in the state by which the electrode part was affixed on the side surface of the honeycomb structure part with the electroconductive bonding material.

  As an electrode part, the thing of the same conditions as the electrode part which comprises the heater of the said invention is preferable.

  Next, the honeycomb structure part to which the electrode part is attached is fired to obtain the heater of the present invention.

  The firing conditions are preferably 60 to 200 ° C. and 0.5 to 2 hours in the air. Thus, the honeycomb structure part and the electrode part are joined using the conductive paste as described above. Therefore, firing (heat treatment) can be performed at a low temperature around 100 ° C. (60 to 200 ° C.). And it can prevent that a honeycomb structure part is damaged at the time of baking, or an electrode part peels off by this.

(3) Heater:
An example of the heater (second heater) of the present invention is a heater such as the heater 102 shown in FIG. A heater 102 shown in FIG. 13 includes a tubular honeycomb structure portion 4 and a pair of electrode portions 21 and 21 joined to the side surface 5 of the honeycomb structure portion 4 via a conductive joint portion 23. The honeycomb structure part 4 has a partition wall 1 that partitions and forms a plurality of cells 2 extending from one end surface 11 to the other end surface 12 that serve as a flow path for the lubricating fluid, and an outer peripheral wall 3 that is positioned at the outermost periphery. . The partition 1 is made of a material mainly composed of ceramics and generates heat when energized. The shape of the electrode part 21 is such that the area of the joint portion of the electrode part 21 is smaller than the area of the shape surrounding the outer periphery of the electrode part 21. Or the shape of the electrode part 21 is a shape in which the corner | angular part was formed in the curve shape in the rectangle. And the electroconductive joining part 23 contains the metal formed by the thermal spraying method, the cold spray method, or the plating method. In the heater 102, the terminal portion 22 is disposed on the electrode portion 21. The terminal portion 22 is a portion to which wiring from an external power source or the like is connected.

  In such a heater 102, the conductive joint portion 23 is “containing a metal formed by thermal spraying, cold spraying, or plating”. Since the conductive joint portion 23 is formed by the above method, it is physically attached to the side surface 5 of the honeycomb structure portion 4. The conductive joint portion 23 functions as an “electrode” together with the pair of electrode portions 21 and 21. And since the electroconductive joining part 23 is directly formed on the surface of a honeycomb structure part and is a thing with low electrical resistance, the electroconductive joining part 23 can flow a big electric current. The heater 102 has a shape in which the shape of the electrode portion 21 is “the area of the joint portion of the electrode portion is smaller than the area of the shape surrounding the outer periphery of the electrode portion”. Alternatively, the heater 102 may have a shape in which an electrode portion is “rectangular and has corners formed in a curved shape”. Therefore, the shape of the electrode part 21 in the heater 102 is the above-mentioned “shape in which thermal stress is reduced”. Therefore, it is possible to prevent the electrode part 21 from being peeled off from the honeycomb structure part 4 after the electrode part 21 is joined to the honeycomb structure part 4. Furthermore, it is possible to prevent cracks from occurring in the honeycomb structure portion 4 after the electrode portion 21 is joined to the honeycomb structure portion 4. Furthermore, even in a use environment where heating and cooling are repeated, the electrode portion 21 can be prevented from peeling off from the honeycomb structure portion 4 or cracks can be prevented from occurring in the honeycomb structure portion 4. In addition, the same effects as the heater 100 can be obtained.

  As described above, in the heater of the present invention, the pair of electrode portions are joined to the side surface of the honeycomb structure portion via the conductive joint portion. And the magnitude | size (namely, the area of the shape surrounding the outer periphery of a conductive junction part) of this conductive junction part does not have a restriction | limiting in particular. Therefore, like the conductive joint portion 23 of the heater 102 shown in FIG. 13, the area of the shape surrounding the outer periphery of the conductive joint portion 23 may be larger than the area of the shape surrounding the outer periphery of the electrode portion 21. That is, the conductive joint portion 23 may protrude from the electrode portion 21.

  The conductive joint 23 of the heater 102 shown in FIG. 13 has an area larger than the area of the electrode part 21 (that is, “the area of the shape surrounding the outer periphery of the electrode part 21”). Therefore, the conductive joint portion 23 of the heater 102 exhibits a function as an “electrode” together with the pair of electrode portions 21 and 21 in addition to joining the honeycomb structure portion 4 and the electrode portion 21. That is, when a voltage is applied between the pair of electrode portions 21 and 21 of the heater 102, the current flowing from one electrode portion 21 causes the conductive joint portion 23 to join the one electrode portion 21 and the honeycomb structure portion 4. Spread inside. A current flows through the entire honeycomb structure 4 sandwiched between the pair of conductive joints 23 and 23. As described above, the conductive joint portion 23 of the heater 102 can function as an “electrode” together with the pair of electrode portions 21 and 21. FIG. 13 is a perspective view schematically showing still another embodiment of the heater of the present invention.

  In the case where the conductive joint portion 23 has the above-mentioned “having an area larger than the area of the electrode portion 21”, the conductive joint portion 23 has the same shape and thickness as the shape, thickness, and material of the electrode portion 21 described above. The material can be used. This will be specifically described below.

  The shape of the conductive joint portion may be a shape “the area of the joint portion of the conductive joint portion is smaller than the area of the shape surrounding the outer periphery of the conductive joint portion”. In addition, the shape of the conductive joint portion may be a shape “a corner portion is formed in a curved shape in a rectangle”. That is, for example, the shape of the conductive joint portion can be a plate shape in which a plurality of holes are formed. Thus, when the shape of the conductive joint portion is the above shape, the thermal stress generated between the honeycomb structure portion and the conductive joint portion is reduced. In addition, “the shape that surrounds the outer periphery of the conductive joint” is a shape that is an “circular shape that circumscribes the conductive joint and has the shortest circumferential length (ring length)”. It is.

  The material of the conductive joint can be a material containing metal. Specifically, the material similar to the material of the electrode part mentioned above can be mentioned. As a material for the conductive joint, it is desirable that the electrical resistance is low and the thermal expansion coefficient is small. If the electrical resistance is high, a problem may occur due to heat generation of the conductive joint itself during energization. Further, when the thermal expansion coefficient is larger than that of ceramics, the interface between the conductive joint portion and the honeycomb structure portion may be peeled off or a crack may be generated in the honeycomb structure portion. For this reason, it is more desirable that the thermal expansion coefficient of the conductive joint is close to that of ceramics.

  The thickness of the conductive joint is preferably 100 to 3000 μm, more preferably 200 to 1000 μm. The preferred range of the thickness of the conductive joint may vary depending on the material of the conductive joint. When the thickness is less than 100 μm, a problem may occur due to resistance heating of the conductive joint itself, or the joint strength may be reduced. When the thickness is greater than 3000 μm, the thermal stress of the honeycomb structure portion and the conductive joint portion increases, and cracks may be generated in the honeycomb structure portion, or the interface between the honeycomb structure portion and the conductive joint portion may be peeled off.

  The ratio (joint part area ratio) of "joint area (joint surface) to the honeycomb structure part of the conductive joint" relative to "the area of the shape surrounding the outer periphery of the conductive joint" is 40 to 95%. It is preferable. This may vary depending on the material of the conductive joint and the thickness of the electrode. In order to reduce thermal stress, it is desirable to reduce the area of the joint portion (joint surface). However, if the area is too small, the energization performance of the heater (honeycomb structure) may be reduced. For this reason, it is preferable to take a balance so as to ensure the mechanical reliability of the joint portion of the conductive joint portion by reducing the thermal stress without degrading the energization performance.

  In addition, as the electrode part 21 of the heater 102, an electrode part similar to the electrode part 21 of the heater 100 described above can be appropriately selected and used. Further, as the honeycomb structure portion 4 of the heater 102, a honeycomb structure portion similar to the honeycomb structure portion 4 of the heater 100 described above can be appropriately selected and used.

  In the heater (second heater) of the present invention, it is also preferable that the terminal portion 22 and the rod-shaped terminal portion 26 are disposed on the electrode portion 21 as in the heater 103 shown in FIG. The rod-shaped terminal portion 26 is preferably electrically connected to the terminal portion 22. In this case, it is preferable that a wire from an external power source or the like is connected to the rod-shaped terminal portion 26. Further, when the heater of the present invention has the rod-shaped terminal portion 26, as shown in FIG. 14, the terminal portion 22 is disposed along the “side surface on which no electrode portion is disposed” of the honeycomb structure portion. It is preferable. FIG. 14 is a perspective view schematically showing still another embodiment of the heater of the present invention.

(4) Heater manufacturing method:
Next, a method for manufacturing the heater 102 shown in FIG. 13 will be described.

  First, the honeycomb structure is manufactured in the same manner as the manufacturing method of the embodiment of the heater of the present invention described above. Next, a “metal-containing coating film” is formed on the side surface of the manufactured honeycomb structure portion by a thermal spraying method, a cold spray method, or a plating method. Then, an electrode part is affixed on this coating film. Thereby, it will be in the state where the electrode part was affixed on the side surface of the honeycomb structure part via the electroconductive joining part. In this way, the heater of the present invention (heater 102 shown in FIG. 13) can be obtained.

  As in the manufacturing method of the embodiment of the heater of the present invention described above, the oxide film layer is removed from the side surface of the honeycomb structure portion, and the thermal spraying method is performed on the side surface of the honeycomb structure portion from which the oxide film layer has been removed. It is preferable to form a “metal-containing coating film” by a cold spray method or a plating method. Further, in order to form a “metal-containing coating film”, a method combining any one of a thermal spraying method, a cold spray method, and a plating method may be employed.

  Specific examples of the method for forming the conductive joint by the thermal spraying method include the following methods. First, of the side surfaces of the honeycomb structure portion, two side surfaces (electrode portion disposition surfaces) on which the electrode portions are disposed are sandblasted. By this sandblasting, the surface on which the electrode part is disposed is roughened and the oxide film layer is removed from the surface on which the electrode part is disposed. Next, a protective cover is provided on a side surface other than the electrode portion installation surface so as to cover the side surface. Next, the powder raw material heated and melted is sprayed onto the electrode portion arrangement surface. In this way, a coating film that becomes a conductive joint can be formed on the surface of the electrode part. Examples of the powder raw material include pure nickel, nickel alloy, pure aluminum, aluminum alloy, pure copper, copper alloy, pure molybdenum, and pure tungsten, as will be described later. Moreover, the temperature at which the powder raw material is heated and melted varies depending on the methods shown below, and is preferably set as appropriate.

  According to such a thermal spraying method, it is difficult to completely densify the conductive joint. That is, according to the thermal spraying method, it is possible to produce a conductive joint in which a plurality of pores are formed inside the conductive joint. Such a conductive joint has an improved relaxation function against thermal stress because Young's modulus decreases due to the formation of pores.

  Examples of the thermal spraying method include a plasma spraying method, a high-speed flame spraying method (HVOF method), an arc spraying method, and a flame spraying method.

  The plasma spraying method is an electric spraying method. A method for spraying the powder raw material onto the honeycomb structure portion (electrode portion arrangement surface) using this plasma spraying method will be specifically described below. First, in a gas such as argon, nitrogen or helium, a direct current arc is generated by applying a voltage between the cathode and the anode. When a DC arc is generated in this way, the gas is dissociated or ionized to continuously generate a plasma arc. Next, by narrowing down this plasma arc with a cooled nozzle, a high-speed jet gas (plasma jet) of about 10,000 ° C. is ejected. Next, a powder raw material is supplied into the plasma jet. Then, by supplying the powder raw material into the plasma jet, the powder raw material can be accelerated while being melted, and the powder raw material heated and melted can be sprayed onto the surface where the electrode portion is disposed. According to this method (plasma spraying method), high melting point materials such as ceramics can be sprayed. Among the plasma spraying methods, in particular, the low-pressure plasma spraying method is difficult to mix impurities and oxides into the formed conductive joints when the plasma spraying apparatus is evacuated and then sprayed with Ar gas or the like. There is an advantage. Therefore, this low pressure plasma spraying method is useful when forming a conductive joint having a low electric resistance.

  In the case where the conductive joint is formed by the plasma spraying method, examples of the powder raw material include pure nickel, nickel alloy, pure aluminum, aluminum alloy, pure copper, copper alloy, pure molybdenum, and pure tungsten. Examples of nickel alloys include NiCr and NiAl. Examples of the aluminum alloy include AlSi. Examples of the copper alloy include CuNi.

Moreover, when forming a conductive junction by a plasma spraying method, examples of the powder raw material include composite materials containing nickel and ceramic particles (Ni / SiC, Ni / Al ₂ O _3, etc.), aluminum and ceramic particles. Composite materials (Al / SiC, Al / Al ₂ O ₃ etc.), composite materials containing copper and ceramic particles (Cu / SiC, Cu / Al ₂ O ₃ etc.) and the like can be mentioned. Examples of the ceramic particles include SiC and Al ₂ O ₃ . When each of the composite materials described above is used, it is possible to obtain a conductive joint having a low electrical resistance, a low thermal expansion coefficient, and a thermal expansion coefficient close to the ceramic constituting the honeycomb structure. Such a conductive joint has a reduced thermal stress generated during a cooling cycle.

  Pure molybdenum and pure tungsten have a lower coefficient of thermal expansion than other metals. Therefore, by using pure molybdenum or pure tungsten as a powder raw material, it is possible to obtain a conductive joint having a low electrical resistance, a low thermal expansion coefficient, and a thermal expansion coefficient close to the ceramic constituting the honeycomb structure part. it can. Such conductive joints are reduced in thermal stress generated during the cooling cycle. Further, when pure molybdenum or pure tungsten is used as a powder raw material, a coating film that becomes a conductive joint can be satisfactorily formed. As described above, when pure molybdenum or pure tungsten is used, the thermal stress generated during the cooling cycle is reduced like a composite material including ceramic particles such as a composite material including nickel and ceramic particles. can get.

  Next, the high-speed flame spraying method (HVOF method) is a gas spraying method. A method for spraying the powder raw material onto the honeycomb structure portion (electrode portion arrangement surface) using this high-speed flame spraying method will be specifically described below. First, combustion gas is generated by burning a hydrocarbon system or a mixed gas of hydrogen gas and oxygen. Next, let this combustion gas be a high-temperature supersonic combustion gas (gas jet). Thereafter, the powder raw material is supplied to the gas jet, the powder raw material is melted and accelerated in the gas jet, and the heated and melted powder raw material can be sprayed onto the electrode portion arrangement surface. In addition, the temperature which generate | occur | produces combustion gas is about 2000-3000 degreeC. According to the HVOF method, it is possible to form a conductive joint having excellent denseness and adhesion.

  In the case where the conductive joint is formed by the HVOF method, examples of the powder raw material include pure nickel, a nickel alloy, a composite material including nickel and ceramic particles, and the like. When the composite material is used, it is possible to obtain a conductive joint having a low electrical resistance, a low thermal expansion coefficient, and a thermal expansion coefficient close to that of the ceramic of the honeycomb structure part. Such a conductive joint has a reduced thermal stress generated during a cooling cycle. The particle diameter of the powder raw material is preferably 0.1 to 150 μm, more preferably 10 to 50 μm.

  Specific examples of the method for forming the conductive joint by the cold spray method include the following methods. First, in the same manner as the above-described thermal spraying method, the electrode portion disposition surface is sandblasted, and a protective cover is disposed on the side surface other than the electrode portion disposition surface so as to cover this side surface. Next, using a gas such as nitrogen gas, argon gas, air, or the like at a temperature of about 200 to 600 ° C. as a carrier gas, the powder raw material is caused to collide with the electrode portion arrangement surface at an ultra high speed. In this way, the powder raw material is plastically deformed in the solid phase state by colliding the powder raw material with the electrode portion arrangement surface at an ultrahigh speed. In this way, a coating film derived from the powder raw material can be formed on the electrode part arrangement surface. The carrier gas is set at a temperature lower than the melting point or softening point of the powder raw material.

  What can be used as a powder raw material in the cold spray method is mainly a soft metal that is more easily plastically deformed than the powder raw material that can be used in the above-described thermal spraying method. Further, in the cold spray method, since the melting temperature of the powder raw material is lower than that of the above thermal spraying method, the powder raw material hardly undergoes thermal alteration or oxidation. Therefore, there is an advantage that it is close to the material characteristics of the bulk (solid mass).

  Examples of the apparatus used for the cold spray method include the following. That is, as the above apparatus, a gun that injects and heats a powder raw material that is heated and accelerated to heat the powder raw material, a heater that heats the carrier gas, a feeder that supplies the powder raw material, and the pressure, temperature, and supply of the carrier gas One with a controller that controls the amount. The particle diameter of the powder raw material is preferably 0.1 to 150 μm, more preferably 10 to 50 μm. If the particle diameter of the powder raw material is small, there is a risk of blocking the gun injection port during use.

  Examples of the powder raw material include pure nickel, pure aluminum, and pure copper.

  Specific examples of the method for forming the conductive joint by plating include the following methods. First, in the same manner as the thermal spraying method, the electrode portion disposition surface is sandblasted, and a protective cover is disposed on a side surface other than the electrode portion disposition surface so as to cover the side surface. Next, a plating process is performed on the electrode portion arrangement surface. In this way, a conductive joint can be formed on the electrode portion-providing surface.

  Examples of the plating method include an electroless plating method, an electrolytic plating method, or a combination of these. In the electroless plating method, it is difficult to form a conductive joint having a large thickness. Therefore, after forming a lower layer (first layer comprising a conductive joint) by an electroless plating method, an upper layer (second layer comprising a conductive joint) can be formed on the lower layer by an electrolytic plating method. . By combining the electroless plating method and the electrolytic plating method in this way, a thick conductive joint can be formed.

  Examples of the plating material used for the plating method include pure nickel and pure copper.

  Note that the conductive joint can be formed by a combination of methods such as thermal spraying, cold spraying, and plating. For example, after the lower layer is formed by an electroless plating method, the upper layer can be formed on the lower layer by a cold spray method. In addition, what consists of this lower layer and an upper layer becomes a conductive junction. By combining a plurality of methods in this way, the conductive joint can be formed thick. In each of the above methods, the sand blasting process and the operation of disposing the protective cover may be adopted as appropriate.

  Next, an electrode part is affixed from above the conductive joint. Thereby, it will be in the state where the electrode part was affixed on the side surface of the honeycomb structure part via the electroconductive joining part. In this way, the heater of the present invention is obtained. There is no restriction | limiting in particular as a method of affixing an electrode part, A general-purpose joining method can be utilized. Examples thereof include soldering and a method using the above-described conductive paste. Note that “through the conductive joint” means that the electrode portion and the honeycomb structure are joined directly or indirectly by the conductive joint. For example, in the heater 102, the electrode portion and the honeycomb structure portion are indirectly joined by the conductive joint portion.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
First, the honeycomb structure part which has Si composite SiC as a main component was produced. Specifically, SiC powder, metal Si powder, water, and an organic binder were mixed and kneaded to prepare a clay. Next, this clay was formed into a honeycomb shape to prepare a honeycomb formed body. Next, the obtained honeycomb formed body was fired in an inert gas atmosphere, so that a honeycomb structure part containing Si composite SiC as a main component was produced. The porosity of the obtained honeycomb structure portion was about 40%.

The shape of the honeycomb structure portion was a cylindrical shape with a square end face. The length of one side of the end face rectangle was 38 mm. The length of the honeycomb structure portion in the cell extending direction was 50 mm. The partition wall thickness was 0.38 mm. The thickness of the outer peripheral wall was 0.38 mm. The cell density of the honeycomb structure part was 47 cells / cm ² . The specific resistance of the partition walls and the outer peripheral wall was 30 Ω · cm.

  A conductive bonding material was applied to a pair of parallel surfaces of the four side surfaces of the honeycomb structure portion and one surface of each of the two electrode portions. The size of the conductive bonding material applied to the side surface of the honeycomb structure portion was set to 36 mm × 48 mm × about 0.5 mm. As the conductive bonding material, a conductive paste containing nickel powder and a silicate solution was used. The electrode part which apply | coated the electroconductive joining material was affixed on each of a pair of parallel surface in 4 surfaces of the outer peripheral wall of a honeycomb structure part. At this time, the electrode portion is attached to the honeycomb structure portion via the conductive bonding material. And the electrode part which apply | coated the electroconductive joining material was affixed on a pair of parallel surface of a honeycomb structure part, Then, it baked and the heater was produced. The electrode portion was shaped like the electrode portion 21 disposed in the heater 100 shown in FIG. Specifically, the electrode part 21 used was a plate having a plurality of holes. Further, the electrode portion 21 is provided with a terminal portion 22. The conditions for firing the conductive bonding material (bonding the electrode portion to the honeycomb structure portion) were a temperature of 100 ° C. and a holding time of 60 minutes. The size of the used electrode part was 32 mm × 43 mm × 0.2 mm. The material of the electrode part was pure metal Ni (purity 99.9% or more). The size of the conductive joint was 36 mm × 48 mm × about 0.5 mm. In addition, the electrode part used what roughened the surface by sandblasting. Similarly, other examples and comparative examples also used electrode portions whose surfaces were roughened by sandblasting.

  The obtained heater was subjected to a “joining test”, “electric current heating test”, and “cooling cycle test”. In the “electric heating test”, the maximum temperature at 100 V (after 15 seconds) was 118 ° C.

(Joining test)
The electrode peeling and crack generation status of the heaters of Examples and Comparative Examples were evaluated by appearance observation and non-destructive ultrasonic flaw detection tests. The joining test is a test for determining the presence or absence of electrode peeling and cracks in the heater. A case where electrode peeling or cracking was observed in the appearance observation or ultrasonic flaw detection test was judged as rejected (B), and a case where electrode peeling or cracking was not seen in the ultrasonic flaw testing was judged as acceptable (A). The electrode peeling means that at least a part of the electrode part is peeled from the honeycomb structure part.

(Electric heating test)
An electric heating test in the atmosphere was performed for the performance evaluation on the heater that had a good result (pass (A)) in the “joining test”. Specifically, when the voltage applied to the heater (applied voltage) was the conditions shown in Table 1, the temperature of the honeycomb structure at each voltage was measured. After applying the predetermined voltage shown in Table 1, the temperature rises to 100 ° C. within 60 seconds was regarded as acceptable (A).

(Cooling cycle test)
A cooling / heating cycle test was performed on the heaters of the examples and comparative examples. Specifically, an operation in which a temperature cycle of 50 minutes was performed 50 times for the heater was performed on the heater. The operation for one cycle was an operation of “increasing, holding, and lowering the temperature between −40 ° C. and + 125 ° C.”. After the above cooling cycle test, the above “joining test” was performed on the electrode joint portion of the heater to confirm the presence or absence of cracks and interface peeling. Those in which no cracks or interfacial delamination occurred were regarded as acceptable (A). Moreover, the thing which a crack or interface peeling generate | occur | produced was made into the rejection (B).

(Example 2 to Example 58)
A heater was produced in the same manner as in Example 1 except that the conditions of the heater were changed as shown in Tables 1 and 2. About the produced heater, the "joining test", the "electric current heating test", and the "cooling cycle test" were performed by the said method. The “partition wall material” shown in Tables 1 and 2 was used as the “partition wall material” in each example. Here, the manufacturing method of the honeycomb structure part which consists of each “partition wall material” shown in Tables 1 and 2 is shown below. In addition, when the material of the partition was “Si composite SiC”, a honeycomb structure part was manufactured by the same method as in Example 1.

  In Examples 23 to 26, the material of the partition was “Si impregnated SiC”. A method for producing a honeycomb structure having partition walls made of Si-impregnated SiC is as follows. Specifically, SiC powder, an organic binder, and water were mixed and kneaded to prepare a clay. Next, this clay was formed into a honeycomb shape to prepare a honeycomb formed body. Next, a lump of metal Si was placed on the obtained honeycomb formed body, and the honeycomb formed body was impregnated with Si in a reduced pressure argon (Ar) gas atmosphere. In this way, a honeycomb structure part mainly composed of Si-impregnated SiC was produced.

  In Examples 27 to 38, 48, 50, 52, 54, 56, and 58, the material of the partition was “recrystallized SiC”. A method for manufacturing a honeycomb structure portion having partition walls made of recrystallized SiC is as follows. First, raw materials containing SiC powder, an organic binder, and water were mixed and kneaded to prepare a clay. Next, this clay was formed into a honeycomb shape to prepare a honeycomb formed body. Next, the obtained honeycomb formed body was fired at a predetermined temperature (1600 to 2300 ° C.) in a nitrogen gas atmosphere. In this way, a honeycomb structure part was produced.

  In Examples 39 to 42, the material of the partition walls was “reactive sintered SiC (porous)”. “Reactive sintered SiC (porous)” refers to porous reactive sintered SiC. The manufacturing method of the honeycomb structure part which has the partition which consists of reaction sintering SiC (porous) is as follows. First, a clay is prepared by mixing and kneading silicon nitride powder, carbonaceous material, silicon carbide and graphite powder. Next, this clay was formed into a honeycomb shape to prepare a honeycomb formed body. Next, the honeycomb formed body was primarily fired in a non-oxidizing atmosphere to obtain a primary fired body. Next, the obtained primary fired body was heated and decarburized in an oxidizing atmosphere to remove the remaining graphite. Next, the “decarburized primary fired body” was subjected to secondary firing at a predetermined temperature (1600 to 2500 ° C.) in a non-oxidizing atmosphere. In this way, a honeycomb structure part was produced.

  In Examples 43 to 46, the material of the partition walls was “reactive sintered SiC (dense)”. “Reaction sintered SiC (dense)” means dense reaction sintered SiC. The manufacturing method of the honeycomb structure part which has the partition which consists of reaction sintering SiC (dense) is as follows. First, SiC powder and graphite powder were mixed and kneaded to prepare clay. Next, this clay was formed into a honeycomb shape to prepare a honeycomb formed body. Next, the honeycomb formed body was impregnated with “molten silicon (Si)”. Thereby, the carbon which comprises graphite and the silicon | silicone impregnated were made to react, and SiC was produced | generated. In this way, a honeycomb structure part was produced.

  In Tables 1 and 2, “bonded portion area ratio” means a ratio of “area of the bonded portion (bonded surface) of the electrode portion” to “area of the shape surrounding the outer periphery of the electrode portion”. Further, Ni, Cu, Al, Mo, and W in the “Material” column of the “electrode part” are pure metals, respectively. The purity of Ni is 99.9% or more, Cu is 99.95% or more, Al is 99.5% or more, Mo is 99.95% or more, and W is 99.95%. “SUS304” means SUS304, which is one of the types of stainless steel. “Cu / W” means a composite material of copper and tungsten. “Cu / Mo” means a composite of copper and molybdenum. As both materials, those having a volume ratio of W and Mo of 85% were used. “SiC / Al” means a composite of SiC and aluminum. “C / Cu” means a composite of carbon and copper. Both materials used were those having a volume ratio of SiC and C of 70%. In the “Structure” column of the “electrode part”, the number of the drawing is shown, which means that the structure is the same as the structure of the “electrode part shown in each drawing”. The same applies to Table 3.

  About the heaters of Examples 15 to 22, 27 to 34, 39 to 42, and 47 to 58, an energization heating test was performed in the atmosphere with the applied voltage of the heater being 20 to 60 V. As a result, it was found that the heater of each of the above examples can be heated and heated well in the same manner as the heater of Example 1. Specifically, for example, in the heater of Example 15, the maximum temperature at 20 V (after 15 seconds) was 107 ° C. Thus, even if the applied voltage is greatly reduced by adjusting the specific resistance of the partition walls and the outer peripheral wall of the honeycomb structure part (even when the applied voltage is set to a low power range (ie, 60 V or less)). It was found that the heater was favorable in terms of operation (heat generation performance, etc.).

(Comparative Example 1)
A honeycomb structure was produced in the same manner as in Example 1. Further, an electrode part was produced in the same manner as in Example 1. The obtained electrode part was joined to the obtained honeycomb structure part using “Ag—Cu—Ti” (manufactured by Tanaka Kikinzoku Co., Ltd.), which is an active metal solder, to obtain a heater. Therefore, in the obtained heater, the electrode part was joined to the honeycomb structure part through the active metal brazing. “Ag—Cu—Ti”, which is an active metal braze, is generally used as a bonding material for ceramic bonding. The material of the electrode part was the same pure metal Ni as in Example 1. A vacuum atmosphere furnace was used for joining the electrode part and the honeycomb structure part. Then, the electrode part and the honeycomb structure part were joined by the active metal solder by holding at 850 ° C. for 10 minutes with the active metal solder sandwiched between the electrode part and the honeycomb structure part. About the obtained heater, the "joining test" was done by the said method. The results are shown in Table 2. As a result of the joining test, cracks were generated in the vicinity of the electrode end portion where both electrode portions were joined in the honeycomb structure portion. This crack could be clearly confirmed from the appearance observation. From this, it is considered that the thermal stress on the ceramic (honeycomb structure) side is large.

(Comparative Example 2)
A heater was produced in the same manner as in Comparative Example 1 except that the material of the electrode part was SUS304. About the obtained heater, the "joining test" was done by the said method. The results are shown in Table 2. As in Comparative Example 1, the occurrence of cracks was confirmed.

(Comparative Example 3)
A heater was produced in the same manner as in Example 1 except that the electrode part (electrode part 21E) was rectangular as shown in FIG. About the obtained heater, the "joining test", the "electric current heating test", and the "cooling cycle test" were performed by the said method. The results are shown in Table 2. FIG. 12 is a plan view schematically showing an electrode portion 21E constituting the heater of Comparative Example 3. As shown in Table 2, when the shape of the electrode portion was “rectangular” as shown in FIG. 12 (the four corners were right angles), it was well bonded in the “bonding test”. However, in the “cooling cycle test”, due to the thermal stress generated during the cooling cycle test, electrode peeling (interfacial peeling) occurred in both electrode portions joined to the honeycomb structure portion, which was rejected (B).

  From the results of the “energization heating test” for the heaters of Examples 1 and 2 shown in Table 1, the honeycomb structure was heated satisfactorily to 100 ° C., regardless of the voltage being 10 to 400 V. I understand that. Although not shown in Tables 1 and 2, the higher the applied voltage, the shorter the temperature raising time from room temperature to 100 ° C.

  From the results of the “cooling cycle test” shown in Tables 1 and 2, it can be seen that the heaters of the present invention (Examples 1 to 58) did not cause interface peeling or cracks. On the other hand, when the shape of the electrode part is a “rectangular shape” (four corners are right angles) as shown in FIG. 12 as in Comparative Example 3, the corner part after the cooling cycle due to stress concentration on the electrode corner part. Electrode peeling (interfacial peeling) occurred.

  In the manufacture of the heaters of Examples 1 to 58, the bonding temperature between the electrode portion and the honeycomb structure portion was as low as 100 ° C., which was effective in reducing the residual stress. On the other hand, in the manufacture of the heater of Comparative Example 1, since normal brazing for ceramic bonding using active metal brazing is performed, the bonding temperature between the electrode portion and the honeycomb structure portion is as high as 850 ° C. Cracks occurred due to stress. The heaters of Examples 1 to 58 have excellent current-carrying performance despite the fact that the electrode part is joined to the honeycomb structure part at a low temperature, and cracks and electrode peeling hardly occur after joining and after the thermal cycle test. It was a heater.

(Examples 59 to 79)
“Each condition of the heater was changed as shown in Table 3” and “A conductive joint was formed on a pair of parallel side surfaces of the honeycomb structure portion by the method shown in Table 3, and the conductive joint was passed through this conductive joint. A heater was manufactured in the same manner as in Example 1 except that the electrode part and the honeycomb structure part were joined. About the obtained heater, the "joining test", the "electric current heating test", and the "cooling cycle test" were performed by the said method. The size of the conductive joint was 20 mm wide × 36 mm long, and the thickness was as shown in Table 3. The electrode used was pure metal Ni (purity 99.9% or more), the size was half the length of the conductive joint (ie 18 mm), the width was 20 mm, and the thickness was 0.5 mm. It was. In addition, as the honeycomb structure portion in each example, one made of “partition wall material” shown in Table 3 was used. The manufacturing method of the honeycomb structure part which consists of each "partition material" shown in Table 3 is the same method as the above-mentioned method, respectively.

In Table 3, “SiC / Ni” in the “Material” column of “Conductive joint” means a composite material of SiC and nickel. “Al ₂ O ₃ / Ni” means a composite of Al ₂ O ₃ and nickel. “SiC / Cu” means a composite of SiC and copper. “Al ₂ O ₃ / Cu” means a composite of Al ₂ O ₃ and copper. “Al ₂ O ₃ / Al” means a composite of Al ₂ O ₃ and aluminum. The volume fraction of ceramic particles in these composite materials was 55%. Ni, Cu, Al, Mo, and W are pure metals. Pure metal powder was used in the thermal spraying method and the cold spray method. The powder purity is 99.7% or more for Ni, 99.5% or more for Cu, 99.7% or more for Al, 99.9% or more for Mo, and 99.9% for W. The “thermal spraying method” in the “formation method” column of the “conductive joint” means a low pressure plasma spraying method.

  The formation of the conductive joint by the “thermal spraying method” was specifically performed by the following method. First, after placing the honeycomb structure in the thermal spraying apparatus, the honeycomb structure was evacuated to make a vacuum, and then replaced with Ar gas. Next, while supplying the powder raw material (shown in the “Material” column of “Conductive joint” in Table 3) into the plasma jet, the powder raw material is heated and melted on a predetermined side surface of the honeycomb structure portion. Spray. In this way, a thin-film conductive joint made of the powder raw material is formed on the side surface of the honeycomb structure.

  The formation of the conductive joint by the “cold spray method” was specifically performed by the following method. First, using compressed air as a carrier gas, a powder raw material (shown in the “Material” column of “Conductive joint” in Table 3) is caused to collide with a predetermined side surface of the honeycomb structure at an ultra high speed. In this way, a thin-film conductive joint made of the powder raw material is formed on the side surface of the honeycomb structure.

  Formation of the conductive joint by the “plating method” is performed by preparing a plating material (shown in the “Material” column of “conductive joint” in Table 3) and forming the film by the electroless plating method. Thereafter, film formation is performed by electrolytic plating. The film formation by the electrolytic plating method is performed in order to increase the film thickness of the conductive joint portion. In this way, a thin-film conductive joint made of the plating material is formed on the side surface of the honeycomb structure.

  In the case where the conductive joint portion is formed by the “thermal spraying method”, “cold spray method”, and “plating method”, the electrode portion is formed on the conductive joint portion by using the same conductive paste as in Example 1. Join.

  The heater of the present invention can be suitably used for heating a lubricating fluid such as engine oil or transmission fluid.

1: partition wall, 2: cell, 3: outer peripheral wall, 4: honeycomb structure part, 5: side face, 11: one end face, 12: the other end face, 21: electrode part, 21A, 21B, 21C, 21D, 21E: Electrode portion, 22: terminal portion, 23: conductive joint portion, 24: shape surrounding the outer periphery of the electrode portion, 25: electrode material, 26: rod-shaped terminal portion, 31: surface on the honeycomb structure portion side, 32: honeycomb structure portion Surface opposite to the side surface, 33: ridge, 34: partial electrode, 35: corner, 36: curved portion, 100, 101, 102, 103: heater, H1, H2: height, D1, D2: distance, W1, W2: width.

Claims (8)

A tubular honeycomb structure part having a partition wall defining a plurality of cells extending from one end face to the other end face as a flow path for a lubricating fluid, a cylindrical honeycomb structure part having an outer peripheral wall located at the outermost periphery, and a side surface of the honeycomb structure part A pair of electrode parts joined to each other through a conductive joint part,
The partition wall is made of a material mainly composed of ceramics, and the entire honeycomb structure part generates heat by energization,
The shape of the electrode part is such that the area of the joint part of the electrode part is smaller than the area of the shape surrounding the outer periphery of the electrode part, or the shape of the electrode part is rectangular and the corners are curved Is a shape formed in a shape,
A heater for heating a lubricating fluid, wherein a ratio of an area of a joint portion of the electrode part to an area of a shape surrounding an outer periphery of the electrode part is 40 to 95% .   The conductive bonding material includes a conductive paste containing a polyamide resin, an aliphatic amine and silver flakes, a conductive paste containing a silver compound, a silicate solution and water, a conductive powder containing nickel powder and a silicate solution. The heater according to claim 1, wherein the heater is one selected from the group consisting of a conductive paste and a conductive paste containing aluminum oxide, graphite, and a silicate solution. It said partition wall, SiC, heater according to claim 1 or 2 as a main component a metal-impregnated SiC, metal composite SiC, and one selected from the group consisting of metal composite _Si 3 _{N 4.} The heater according to any one of claims 1 to 3 , wherein the electrode portion has a plate shape in which a plurality of holes are formed. The heater according to any one of claims 1 to 3 , wherein a shape of the electrode portion is a shape in which a plurality of strip-shaped electrode materials are arranged in a lattice pattern. The shape of the electrode portion is a plate shape in which a protrusion is formed such that a surface on the honeycomb structure portion side is depressed and a surface opposite to the surface on the honeycomb structure portion side protrudes. The heater according to any one of claims 1 to 3 , wherein the ridges are formed on the electrode portion so as to be arranged in a lattice pattern. The heater according to any one of claims 1 to 3 , wherein a shape of the electrode part is a comb-like shape having a plurality of strip-like partial electrodes. The heater according to any one of claims 1 to 3 , wherein the electrode portion has a rectangular shape with corners formed in a curved shape.

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