JP6093130B2 - heater - Google Patents

Description

  The present invention relates to a heater (coolant heating type on-vehicle air conditioner heater) that is used by being mounted on an automobile for heating inside the vehicle using a coolant as a heating medium.

  In internal combustion locomotives (ICE) and hybrid vehicles (HEV), the engine cooling water (coolant) temperature has been decreasing year by year due to higher engine efficiency. It has become difficult to use as a heat source for heating. In addition, in an electric vehicle (EV), when heating is used, the proportion of energy consumed for heating may reach more than half of the total energy consumption. As a result, the energy allocated to traveling is greatly increased. The travel distance will be shortened. Similarly, in a plug-in hybrid vehicle (PHEV), when heating is used, a lot of electric energy is consumed for heating, and the travel distance by the electric energy is shortened. In particular, in a hybrid vehicle, since it is necessary to mount many parts in a limited space, it is difficult to mount a large heat medium heating device for heating the vehicle interior.

  Under these circumstances, in recent years, there is an increasing demand for improvement in heat efficiency and miniaturization of a heater used in a heat medium heating device for heating a vehicle interior.

  2. Description of the Related Art Conventionally, a heating medium heating device for heating a vehicle mounted on an automobile has a PTC element (positive characteristic thermistor element) as a heating element as a heater for heating and heating a medium to be heated such as air or coolant. Heaters have been mainly used.

  As an example of such a PTC heater, Patent Document 1 has a structure in which a PTC element is sandwiched by a heat medium distribution box through an electrode plate, an insulating layer, and a heat conduction layer, and heat generated by the PTC element. Discloses a heater that transmits the heat to a medium to be heated via an electrode plate, an insulating layer, a heat conduction layer, and a heat medium distribution box.

  In Patent Document 2, as a heater for a vehicle air conditioner that does not use a PTC element, a carrier having a fluid passage formed in a honeycomb shape or the like, and a film formed on the surface of the carrier, and generates heat when energized. A heater having a heat generating layer for heating the fluid is disclosed.

JP 2008-56044 A JP 2006-35939 A

  However, the PTC heater as disclosed in Patent Document 1 has a problem that it is difficult to reduce the size because the specific resistance is as high as several tens of Ω · cm and it is difficult to increase the heat generation density. Furthermore, since these PTC heaters are separate from the heat generating part (PTC element) and the heat transfer part (heat medium distribution box, etc.), the thermal resistance is large, the thermal efficiency is deteriorated, and the number of parts is large. However, there was also a problem that the assembly was difficult. Further, in the heater disclosed in Patent Document 2, only the heat generating layer formed on the surface of the carrier generates heat, and the carrier itself does not generate heat. Therefore, in order to obtain heat generation necessary for heating the vehicle interior, There is a problem that it is difficult to reduce the size because the size needs to be considerably increased.

  The present invention has been made in view of the above-described problems, and has higher thermal efficiency and can be miniaturized than a heater conventionally used for heating a vehicle, has a small number of parts, and has a simple structure. It is an object of the present invention to provide a heater that can be manufactured easily and at low cost.

  In order to achieve the above object, according to the present invention, the following heater is provided.

[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 coolant that is a medium to be heated, and a peripheral wall located at the outermost periphery; A pair of electrode portions joined to side surfaces of the honeycomb structure portion, the honeycomb structure portion is made of a material mainly composed of ceramics, generates heat when energized, and the thickness of the partition wall is 0.05. Is 0.5 mm, the cell density of the honeycomb structure is 9.3 to 186 cells / cm ² , the specific resistance of the honeycomb structure is 4 to 25 Ω · cm, and the ceramic is Si It is one kind of ceramic selected from the group consisting of impregnated SiC, Si-bonded SiC, recrystallized SiC, reaction-sintered SiC, and sintered SiC, and has a dielectric breakdown strength of 10 to 1000 on the surface of the partition wall. A heater that has an insulating layer of V / μm and is used by being mounted on an automobile for heating inside the vehicle.

[2] The heater according to [1], wherein an aperture ratio of the honeycomb structure portion is 60 to 90%.

  In the heater of the present invention, the honeycomb structure part itself is a heat generating part as well as a heat generating part. That is, since the heat generating part and the heat transfer part are integrated (same) and there are no intermediate inclusions that become thermal resistance between them, the thermal efficiency is high, the structure is simple, and the number of parts is small. Further, since the integrated heat generating portion and heat transfer portion have a honeycomb structure with a large surface area, the area (heat transfer area) in contact with the coolant that is the medium to be heated is large. Furthermore, the specific resistance of the honeycomb structure portion is low, and it is easy to increase the output density (heat generation density). In addition, even when the power density is set to be considerably high, the combination of the partition wall thickness and the cell density of the honeycomb structure portion does not increase the pressure loss and the body temperature when heating the coolant as the medium to be heated. Has been optimized. By having such characteristics, the heater of the present invention exhibits high thermal efficiency, can be miniaturized, has excellent immediate temperature properties, and can be manufactured easily and at low cost.

It is a perspective view showing typically one embodiment of the heater of the present invention. It is a top view which shows typically one end surface of the heater shown in FIG.

  Hereinafter, embodiments of the present invention will be specifically described. However, the present invention is not limited to the following embodiments, and is based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. In addition, it should be understood that modifications, improvements, and the like appropriately added to the following embodiments also fall within the scope of the present invention.

(1) Heater:
The present invention is a heater (coolant heating type on-vehicle air conditioner heater) that is used by being mounted on an automobile for heating inside the vehicle using a coolant as a heating medium. In developing the heater of the present invention, the present inventors first conducted intensive studies on the performance to be satisfied as a coolant heating type on-vehicle air conditioning heater from the viewpoint of thermal efficiency, energy load, durability, and the like. As a result, when the input power, voltage, flow rate and fluid initial temperature are set as shown in Table 1, all of the fluid temperature, the housing temperature and the pressure loss have the performance capable of satisfying the conditions shown in the table. It was found that this is necessary as a coolant heating type on-vehicle air conditioning heater. Based on such knowledge, the present inventors have optimized the various design factors to satisfy the above conditions, and have higher heat efficiency than conventional in-vehicle air conditioning heaters, and coolant heating that can be downsized. Completed on-board air conditioning heater.

  Here, “fluid” refers to a coolant (coolant) that is a medium to be heated in the present invention. The “fluid initial temperature” is the temperature of the coolant before being heated by the heater. This “fluid initial temperature” is measured by a thermocouple arranged on the fluid outlet side of the heater in a state where the heater (honeycomb structure) is not energized. “Fluid temperature” is the temperature of the coolant heated by the heater. This “fluid temperature” is measured by a thermocouple disposed on the fluid outlet side of the heater while the heater (honeycomb structure) is energized. In addition, although the said conditions shown in Table 1 are conditions which should be satisfy | filled when the coolant whose components are ethylene glycol 50 mass% and water 50 mass% is made into a fluid (to-be-heated medium), the to-be-heated of the heater of this invention The component of the coolant as the medium is not limited to this.

  In addition, the “body temperature” in the present invention is the temperature of the honeycomb structure portion when heat is generated by energization. This “body temperature” is measured by a thermocouple brought into contact with the outer peripheral wall of the honeycomb structure portion. Further, in the present invention, the “pressure loss” means a pressure difference between the coolant inlet side (upstream side) and the outlet side (downstream side) of the honeycomb structure portion when coolant is circulated through the honeycomb structure portion. That is. This “pressure loss” is calculated from pressure values measured by pressure gauges attached to the inlet side (upstream side) and the outlet side (downstream side) of the heater (honeycomb structure).

  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 end face of the heater shown in FIG. As shown in these drawings, the heater 100 of the present invention includes a honeycomb structure portion 4 and a pair of electrode portions 21 and 21 joined to the side surfaces of the honeycomb structure portion 4.

  The honeycomb structure portion 4 includes a partition wall 1 that partitions and forms a plurality of cells 2 that extend from one end surface 11 to the other end surface 12 that serve as a flow path for a coolant that is a medium to be heated, and an outer peripheral wall 3 that is positioned at the outermost periphery. It is a cylindrical structure. The honeycomb structure portion 4 is made of a material whose main component is ceramics, and generates heat when energized through a pair of electrode portions 21 and 21 bonded to the side surfaces of the honeycomb structure portion 4. Here, having ceramics as a main component means containing 50% by mass or more of ceramics.

  In the heater 100 of the present invention, the honeycomb structure portion 4 has a specific resistance of 4 to 25 Ω · cm, preferably 3 to 20 Ω · cm, more preferably 2.5 to 10 Ω · cm. The specific resistance of the honeycomb structure portion 4 is significantly lower than the specific resistance of the PTC element used in the PTC heater. For this reason, the heater 100 of the present invention can increase the output density (output per unit volume) by reducing the specific resistance, thereby improving the thermal efficiency and enabling miniaturization. Specifically, a PTC heater having a structure in which a heater of the present invention and a PTC element as described in Patent Document 1 are sandwiched by a heat medium distribution box via an electrode plate, an insulating layer, and a heat conductive layer. And the heater of the present invention can obtain the same output density even if it is downsized to about 1/20 the volume of the PTC heater.

  When the specific resistance of the honeycomb structure portion is less than 4 Ω · cm, among the conditions shown in Table 1, it is difficult to satisfy the condition that the body temperature is 100 ° C. or less. On the other hand, when the specific resistance of the honeycomb structure part exceeds 25 Ω · cm, it becomes difficult to satisfy the condition that the fluid temperature is 70 ° C. or higher among the conditions shown in Table 1. That is, in these cases, there is a possibility that performance required as a coolant heating type on-vehicle air conditioning heater cannot be obtained.

In the case of using as the main component of the honeycomb structure portion 4, as the ceramics that can be made to have a resistivity of 4~25Ω · cm in the honeycomb structure portion 4, S i impregnated SiC, Si bond SiC, recrystallized SiC, Reaction sintered SiC and sintered SiC are mentioned. Among these ceramics, Si impregnated SiC is particularly preferable because it is easy to reduce the specific resistance. The “Si-impregnated SiC” has a structure in which SiC particles are joined to each other through metal Si by surrounding the surface of the SiC particles with a solidified product of metal Si.

  When the honeycomb structure portion 4 is made of a material mainly composed of Si-impregnated SiC, the specific resistance of the honeycomb structure portion can be changed by adjusting the amount of metal Si to be impregnated. Generally, as the amount of metal Si to be impregnated increases, the specific resistance of the honeycomb structure portion becomes smaller.

  The specific resistance of the honeycomb structure part 4 can also be changed by adjusting the porosity of the partition walls 1 of the honeycomb structure part 4. In general, the smaller the porosity of the partition wall 1, the smaller the specific resistance. As a result, electricity easily flows through the partition wall 1.

  Furthermore, the specific resistance of the honeycomb structure part 4 should be changed depending on the type of SiC used as a raw material (α-SiC, β-SiC), the mixing ratio of these raw materials, or the amount of impurities in the metal used as the raw material. Can do.

In the heater 100 of the present invention, the partition wall 1 of the honeycomb structure 4 has a thickness of 0.05 to 0.5 mm, and the density of the cells 2 (cell density) is 9.3 to 186 cells / cm ^2. It is necessary to be.

As in the present invention, in the heater 100 having the honeycomb structure portion 4 as a heat generating portion, when the overall dimensions of the honeycomb structure portion 4 and the heater output are constant, the body temperature and the pressure loss are mainly the partition walls of the honeycomb structure portion 4. 1 and the cell density. And when the present inventors variously examined about the thickness and cell density of the partition 1, the thickness of the partition 1 is 0.05-0.5 mm, and cell density is 9.3-186. In the case of cell / cm ² , it was found that even if the power density was set to be quite high, the housing temperature and pressure loss shown in Table 1 could be satisfied.

  The output density of the heater of the present invention can be adjusted, for example, by adjusting the size of the honeycomb structure portion. 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”.

When the thickness of the partition wall 1 is not included in the range of 0.05 to 0.5 mm and / or the cell density is not included in the range of 9.3 to 186 cells / cm ² , It becomes difficult to satisfy the housing temperature and / or pressure loss shown in FIG. That is, in this case, there is a possibility that the performance required as a coolant heating type on-vehicle air conditioning heater cannot be obtained.

In the heater 100 of the present invention, the partition wall 1 preferably has a thickness of 0.05 to 0.3 mm and a cell density of 23.2 to 186 cells / cm ² . Moreover, it is more preferable that the partition wall 1 has a thickness of 0.05 to 0.1 mm and a cell density of 48 to 186 cells / cm ² .

  When the thickness of the partition wall 1 and the cell density are included in such a range, the output density is further increased by reducing the size of the honeycomb structure part (for example, shortening the length of the honeycomb structure part). Even in this case, the housing temperature and pressure loss shown in Table 1 can be satisfied. For example, as described in Patent Document 1, the output density is set to 5 times or more that of a PTC heater having a structure in which a PTC element is sandwiched by a heat medium distribution box through an electrode plate, an insulating layer, and a heat conductive layer. Even in this case, the housing temperature and pressure loss shown in Table 1 can be satisfied.

  In the heater 100 of the present invention, the aperture ratio of the honeycomb structure portion 4 is preferably 60 to 90%. This is because when the pressure loss and the heat generation density are taken into consideration, it is not very realistic that the aperture ratio of the honeycomb structure portion 4 is outside the above range. The “aperture ratio” as used herein refers to the section of the cell with respect to the total area of the cross section orthogonal to the cell extending direction of the honeycomb structure portion (the area obtained by adding the cell cross sectional area to the cross sectional area of the partition walls and the outer peripheral wall). It means the area ratio.

  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.

  The outer peripheral wall 3 is a wall constituting the side surface 5 of the honeycomb structure part 4. The outer peripheral wall 3 may be formed together with the partition walls 1 in the process of manufacturing the honeycomb structure portion. For example, the partition wall 1 and the outer peripheral wall 3 may be produced by extrusion molding at a time. Alternatively, only the partition wall 1 can be produced by extrusion molding or the like, and the outer peripheral wall 3 can be formed by applying a ceramic material to the outer peripheral portion of the partition wall 1.

  The outer peripheral wall 3 is preferably thick. That the outer peripheral wall 3 is thick means that the outer peripheral wall 3 is thicker than the partition wall 1. If the outer peripheral wall 3 is thick, the strength of the outer peripheral wall 3 as a structure increases. Therefore, it is possible to improve resistance to thermal stress when the electrode portions 21 and 21 are joined. As a result, it becomes easy to suppress the occurrence of damage such as cracks in the outer peripheral wall. In addition, when the heater is used in a state where it is housed in the housing, if the resin is used in at least a part of the housing, the resin may deteriorate and be damaged by locally overheating the heater. is there. If the outer wall 3 is thick and the heat capacity is increased to suppress the temperature rise of the outer wall 3, damage due to deterioration of the resin can be suppressed.

  Although the thickness of the outer peripheral wall 3 depends on the porosity of the outer peripheral wall 3, etc., it is preferably 0.3 to 5 mm, and more preferably 0.5 to 3 mm.

Heater 100 of the present invention, the surface of the partition walls 1 of the honeycomb structure portion 4, the dielectric breakdown strength Ru der having an insulating layer is 10~1000V / μm. Breakdown strength of the insulating layer is good preferable is 100~1000V / μm. The coolant that circulates in the cell 2 as a medium to be heated may contain metallic wear powder generated from automobile parts. For this reason, when the heater 100 is used for a long period of time, the metallic wear powder may adhere to the partition wall 1 or be deposited, resulting in clogging. In such a case, the heater 100 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 wall 1 of the honeycomb structure part 4, metallic wear powder contained in the coolant that is a medium to be heated adheres to and accumulates on the partition wall 1. The short circuit of the heater 100 resulting from clogging can be prevented.

  An example of the insulating layer is an oxide film formed by oxidizing a ceramic component contained in the partition wall 1. Such an oxide film can be formed by high-temperature treatment of the honeycomb structure portion 4 in an oxidizing atmosphere.

  Alternatively, an insulating layer can be provided by coating the surface of the partition wall 1 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 ceramics and “SiO ₂ glass” may 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 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 the electrostatic spray method 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 insulation is improved, but the thermal resistance is increased to heat the coolant that is the medium to be heated. This is because the insulating layer tends to have lower thermal conductivity than the partition. Furthermore, when the insulating layer is thick, 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.

  In addition, the film thickness of an insulating layer means the average film thickness of an insulating layer. Moreover, the film thickness of an insulating layer said here is the value which observed and measured with the optical microscope or the electron microscope using the 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.

  In the present invention, the pair of electrode portions 21 and 21 is for energizing 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 joined to. 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.

  Examples of the material of the electrode portion 21 include stainless steel, copper, nickel, aluminum, molybdenum, tungsten, rhodium, cobalt, chromium, niobium, tantalum, gold, silver, platinum, palladium, and alloys of these metals. it can. The electrode portion 21 is formed using a composite material such as a Cu / W composite material, a Cu / Mo composite material, an Ag / W composite material, a SiC / Al composite material, or a C / Cu composite material. Also good. “Cu / W composite” means a copper tungsten composite. “Cu / Mo composite” means a copper molybdenum composite. “Ag / W composite” means a silver-tungsten composite. “SiC / Al composite material” means a composite material of SiC and aluminum. “C / Cu composite” means a composite of carbon and copper.

  As a material of the electrode part 21, it is desirable that the electric resistance is low, the thermal expansion coefficient is low, and the thermal expansion coefficient is close to the ceramic of the honeycomb structure part 4. The reason why it is desirable that the electric resistance is low is that if the electric resistance is high, a problem may occur due to heat generation of the electrode part itself when energized. The reason why it is desirable that the thermal expansion coefficient is low is as follows. When the thermal expansion coefficient of the electrode material is higher than that of ceramics, the thermal stress generated at the time of joining the electrode part 21 becomes large, causing problems due to interfacial delamination and generation of cracks on the ceramic side (honeycomb structure part 4 side). This is because there are cases.

  The material of the electrode part 21 can be appropriately selected in consideration of the balance of generation of cracks on the ceramics side due to thermal stress, peeling of the interface of the electrode, heat generation of the electrode part itself, cost, and the like. For example, for aluminum, although the electrical resistance is low, the electrode portion 21 may be easily peeled off due to thermal stress due to a high coefficient of thermal expansion. Stainless steel may have a problem in terms of heat generation of the electrode part itself because of its relatively high electrical resistance. In addition, regarding noble metal materials such as gold, silver, platinum, palladium, and rhodium, although the electrical resistance of gold and silver is particularly low, it may cause a problem in material cost. The electrode portion formed using the composite material has a low electrical resistance and a thermal expansion coefficient lower than that of other pure metals such as aluminum, and the thermal expansion coefficient of the ceramic constituting the honeycomb structure portion Therefore, the effect of reducing the thermal stress during the thermal cycle can be expected. The same effect can be obtained even with a material having a lower thermal expansion coefficient than other metals, such as molybdenum and tungsten.

  In the present invention, each of the pair of electrode portions 21 and 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 the embodiment of FIG. 1, an example is shown in which a pair of electrode portions 21 are disposed on two side surfaces 5 facing each other of the honeycomb structure portion 4 whose end surface is formed in a rectangular 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.

  The pair of electrode portions 21 and 21 may have a terminal portion 22 for ensuring electrical connection with a power source or the like. 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.

  When producing the heater body of the present invention, the plate-like or film-like electrode portion 21 is produced separately from the honeycomb structure portion 4, and the produced electrode portion 21 is formed on the two side surfaces 5 of the honeycomb structure portion 4. It is preferable to join. As a method for joining the pair of electrode portions 21 and 21 to the side surface 5 of the honeycomb structure portion 4, for example, a conductive bonding material is disposed on the side surface 5 of the honeycomb structure portion 4, and the electrode portion 21 is formed by the conductive bonding material. And a method of joining the side surface 5 of the honeycomb structure part 4 to each other. When such a joining method is employed, it is preferable that the above-described conductive bonding material is baked at 60 to 200 ° C. to form the conductive bonding portion 23.

  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 the conductive bonding portion 23 that is a fired product, the honeycomb structure portion 4 and the electrode portion 21 are bonded through the conductive bonding portion 23.

  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 100 of this embodiment has good heat generation performance due to energization. Furthermore, when bonding using the conductive bonding material as described above, the bonding temperature is lower than that of general brazing 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 4 when the honeycomb structure portion 4 mainly composed of ceramics and the electrode portion 21 are joined. Furthermore, it is possible to prevent the electrode portion 21 from peeling from the honeycomb structure portion 4.

  In addition, the conductive joint portion 23 that joins the pair of electrode portions 21 and 21 and the honeycomb structure portion 4 may include a metal formed by a thermal spraying method, a cold spray method, or a plating method. . Such a conductive bonding portion 23 functions as an “electrode” together with the pair of electrode portions 21 and 21. Such a conductive joint 23 is preferable in that it can be directly formed on the surface of the honeycomb structure portion 4 as a layer having a low electric resistance. Thereby, a big electric current can be sent through the honeycomb structure part 4. FIG.

  When the conductive joint 23 is formed by a thermal spraying method, a cold spray method, or a plating method, the material of the conductive joint 23 can be the same as the material of the electrode portion 21 described so far. . As the material of the conductive joint portion 23, it is desirable that the electrical resistance is low, the thermal expansion coefficient is low, and the thermal expansion coefficient is close to that of the ceramics of the honeycomb structure portion 4, like the electrode 21 portion described above. If the electrical resistance is high, a problem may occur due to heat generation of the conductive joint itself during energization. Moreover, when the thermal expansion coefficient is higher than that of ceramics, the interface between the conductive joint portion 23 and the honeycomb structure portion 4 may be peeled off, or cracks may be generated in the honeycomb structure portion 4.

  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.

  Specific examples of the method for forming the conductive joint portion 23 by the thermal spraying method include the following methods. First, of the side surfaces of the honeycomb structure portion 4, two side surfaces (electrode portion arrangement surfaces) on which the electrode portions 21 are arranged are sandblasted. The surface of the electrode portion is roughened by the sandblasting process, and the oxide film layer is removed from the surface of the electrode portion. Next, a protective cover is provided on a side surface other than the electrode portion installation surface so as to cover the side surface. Subsequently, the powder raw material heated and melted is sprayed on the electrode portion arrangement surface. In this way, a coating film that becomes the conductive joint portion 23 can be formed on the electrode portion arrangement surface. Examples of the powder raw material include pure nickel, nickel alloy, pure aluminum, aluminum alloy, pure copper, copper alloy, pure molybdenum, and pure tungsten. Further, the temperature at which the powder raw material is heated and melted varies depending on the spraying method, and is preferably set as appropriate.

  According to such a thermal spraying method, it is difficult to completely densify the conductive joint 23. That is, according to the thermal spraying method, it is possible to produce the conductive joint portion 23 in which a plurality of pores are formed. Such a conductive joint 23 has a reduced Young's modulus due to the formation of pores, and therefore has an improved relaxation function against thermal stress.

  Specific examples of the method for forming the conductive joint portion 23 by the cold spray method include the following methods. First, in the same manner as in the 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 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 causing the powder raw material to collide 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 portion 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 thermal spraying method. Moreover, since the melting temperature of the powder raw material is lower than that of the thermal spraying method in the cold spray method, thermal alteration and oxidation of the powder raw material are difficult to occur. Therefore, there is an advantage that it is close to the material characteristics of the bulk (solid mass).

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

  Specific examples of the method for forming the conductive joint portion 23 by plating include the following methods. First, similarly to 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 this side surface. Next, a plating process is performed on the electrode portion arrangement surface. In this way, a coating film that becomes the conductive joint portion 23 can be formed on the surface of the electrode portion.

  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 film thickness. Therefore, after forming a lower layer (ie, a first layer made of a conductive joint) by an electroless plating method, an upper layer (ie, a second layer made of a conductive joint) is formed on the lower layer by an electrolytic plating method. can do. 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.

  The conductive joint can be formed by a combination of methods such as thermal spraying, cold spraying, and plating. For example, after forming the lower layer by an electroless plating method, the upper layer can be formed on the lower layer by a cold spray method. In this case, the conductive junction 23 is composed of the lower layer and the upper layer. By combining a plurality of methods in this manner, the conductive joint portion 23 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.

  The heater of the present invention is usually used in a state where it is stored in a circulation path of a fluid (a coolant to be heated). In the heater of the present invention, the heat generated by the honeycomb structure part by energization is transmitted from the partition walls of the honeycomb structure part to the coolant flowing through the cells, thereby increasing the temperature of the coolant. As described above, in the heater of the present invention, the honeycomb structure itself is not only a heat generating part but also a heat transfer part. That is, since the heat generating part and the heat transfer part are integrated (same) and there are no intermediate inclusions that become thermal resistance between them, the thermal efficiency is high and the number of parts is small. Further, since the integrated heat generating portion and heat transfer portion have a honeycomb structure with a large surface area, the area (heat transfer area) in contact with the coolant that is the medium to be heated is large. Furthermore, as described above, since the specific resistance of the honeycomb structure is significantly lower than the specific resistance of the PTC element used in the PTC heater, the output density (output per unit volume) is reduced by reducing the specific resistance. ) Can be increased. In addition, even when the power density is set to be considerably high, the combination of the partition wall thickness and the cell density of the honeycomb structure portion does not increase the pressure loss and the body temperature when heating the coolant as the medium to be heated. Has been optimized. By having such a configuration, the heater of the present invention has high thermal efficiency, can be reduced in size, is excellent in immediate temperature, and can be manufactured easily and at low cost.

(2) Heater manufacturing method:
Next, a method for manufacturing the heater of this embodiment will be described. Here, an example of a manufacturing method of a heater in which the honeycomb structure portion is made of a material mainly composed of Si-impregnated SiC is shown, but the manufacturing method of the heater of the present embodiment is described in the following manufacturing method. There is no limit.

  First, SiC powder, metal Si powder, water, an organic binder, etc. 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 resulting honeycomb formed body is fired in an inert gas atmosphere to form a honeycomb structure. Thereafter, the resulting honeycomb structure is impregnated with Si in an inert gas atmosphere, whereby a honeycomb structure portion mainly composed of Si-impregnated SiC can be produced.

  In the above-described method for manufacturing a honeycomb structure mainly composed of Si-impregnated SiC, SiC powder, water, an organic binder, and the like may be mixed and kneaded to prepare a clay. That is, the raw material for the clay does not need to contain the metal Si powder.

  Further, when a honeycomb structure part mainly composed of Si-impregnated SiC is manufactured, it is calculated by the formula {content of metal Si / (content of metal Si + content of SiC)} × 100 (%). The metal Si content is preferably 5 to 50%. The metal Si content is more preferably 10 to 40%. By comprising in this way, the specific resistance can be made into a suitable magnitude | size, maintaining the intensity | strength of a partition or an outer peripheral wall.

An SiO ₂ film (oxide film) formed by oxidizing SiC is preferably formed on the surface of the partition as an insulating layer. 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. When the main component of the partition walls is Si-impregnated 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, a pair of electrode portions disposed on the side surface of the honeycomb structure portion is formed. Examples of the material of the electrode part include stainless steel, copper, nickel, aluminum, molybdenum, tungsten, rhodium, cobalt, chromium, niobium, tantalum, gold, silver, platinum, palladium, and alloys of these metals. . As described above, the material of the electrode part can be appropriately selected in consideration of the balance of the generation of cracks in the ceramic due to thermal stress, the peeling of the electrode interface, the heat generation of the electrode part itself, the cost, and the like. In addition, the electrode part has a low thermal expansion coefficient, and its thermal expansion coefficient is close to that of ceramics in the honeycomb structure part, so that it is effective in reducing thermal stress during thermal cycling. Molybdenum, tungsten, Cu / W composite You may form using composite materials, such as a material, Cu / Mo composite material, Ag / W composite material, SiC / Al composite material, C / Cu composite material.

  Next, in order to form the electrode portion, 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.

  The conductive bonding material is preferably one type selected from the group consisting of the conductive paste A, the conductive paste B, the conductive paste C, and the conductive paste D described above.

  Then, 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.

  Finally, the honeycomb structure part to which the electrode part is attached is fired, and the honeycomb structure part and the electrode part are joined 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.

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

(Example 1: Examination of the combination of the partition wall thickness and cell density of the honeycomb structure in a heater having a power density approximately twice that of the conventional product)
First, 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 metallic Si lump is placed on the obtained molded body and fired in a reduced pressure argon (Ar) gas atmosphere to impregnate the molded body with Si, and a honeycomb structure mainly composed of Si-impregnated SiC. Part was produced.

In such a procedure, a honeycomb structure portion in which six cell densities of 50 cpsi, 100 cpsi, 300 cpsi, 600 cpsi, 900 cpsi, and 1200 cpsi are combined with five types of partition wall thicknesses of 2 mil, 4 mil, 12 mil, 20 mil, and 30 mil. Produced. However, among the combinations of the partition wall thickness and the cell density, a combination in which the aperture ratio does not become 60 to 90% (the combination of the cell density and the partition wall thickness that is “−” in Table 2). This honeycomb structure is not manufactured because it is not practical considering pressure loss and heat generation density. For this reason, there are a total of 12 combinations of partition wall thickness and cell density in the actually manufactured honeycomb structure. Note that 1 mil is 1/1000 of an inch and corresponds to about 0.025 mm. Moreover, cpsi is a cell / square inch, and 100 cpsi is equivalent to about 15.5 cells / cm ² .

  The shape (overall shape) of these honeycomb structures was a cylindrical shape with end faces being square. As for the dimensions of the honeycomb structure part, the length of one side of the square on the end face of the honeycomb structure part was 75 mm, and the length of the honeycomb structure part in the cell extending direction was 40 mm.

  A conductive bonding material was applied to a pair of parallel surfaces among the four side surfaces of the honeycomb structure portion and one surface of each of the two electrode portions. As the conductive bonding material, a conductive paste containing nickel powder and a silicate solution was used. An electrode portion coated with a conductive bonding material was attached to the parallel pair of surfaces of the honeycomb structure portion, and then fired to bond the pair of electrode portions to the side surfaces of the honeycomb structure portion. 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 material of the electrode part was pure metal Ni (purity 99.9% or more). The electrode portion used was a surface roughened by sandblasting.

  In this way, 12 types of heaters having different combinations of the partition wall thickness and cell density of the honeycomb structure portion were produced. Note that the specific resistance of the honeycomb structure is adjusted so that the output of these heaters is constant (5 kW). In addition, these heaters are adjusted to have a power density approximately twice that of conventional products by setting the dimensions of the honeycomb structure portion to the above values. The conventional product referred to here is a PTC heater having a structure described in Patent Document 1, and the dimensions in a state in which the PTC element, the electrode plate, the insulating layer, and the heat medium distribution box are combined have a width of 55 mm × It was manufactured to be 45 mm high × 175 mm long, and its specific output density was 11.5 kW / L.

  Using these 12 types of heaters, the input power, voltage, flow rate and fluid initial temperature are set as shown in Table 1, and the fluid (coolant as the medium to be heated) is heated, and the body temperature at the time of the heating And pressure loss were measured, and each heater was evaluated based on the measurement results. As a specific evaluation method, the case where both the housing temperature and the pressure loss satisfy the conditions shown in Table 1 is “A”, and the housing temperature and the pressure loss are both shown in Table 1. The case where it was not satisfied was designated as “B”. The evaluation results are shown in Table 2.

As shown in Table 2, the partition wall thickness of the honeycomb structure part is included in the range of 0.05 to 0.5 mm, and the cell density is included in the range of 9.3 to 186 cells / cm ^2. The evaluation result of the heater was “A” even when the output density was about twice that of the conventional product. On the other hand, heaters whose honeycomb structure partition wall thicknesses and / or cell densities are not included in the above ranges have an evaluation result of “B”, that is, the conditions in which the body temperature and / or pressure loss are shown in Table 1. I was not satisfied.

(Example 2: Examination of combination of partition wall thickness and cell density of honeycomb structure in heater having power density about 5 times that of conventional product)
In the same manner as in Example 1, 12 types of heaters having different combinations of the partition wall thickness and cell density of the honeycomb structure portion were produced. However, these heaters are adjusted to have a power density about five times that of the conventional product by making the size of the honeycomb structure portion smaller than that of the first embodiment. The specific dimensions of the honeycomb structure part were such that the length of one side of the square on the end face of the honeycomb structure part was 55 mm, and the length of the honeycomb structure part in the cell extending direction was 30 mm.

  Using these 12 types of heaters, the input power, voltage, flow rate and fluid initial temperature are set as shown in Table 1, and the fluid (coolant as the medium to be heated) is heated, and the body temperature at the time of the heating And pressure loss were measured, and each heater was evaluated based on the measurement results. The specific evaluation method is the same as in the case of Example 1. The evaluation results are shown in Table 3.

As shown in Table 3, the partition wall thickness of the honeycomb structure part is included in the range of 0.05 to 0.3 mm, and the cell density is included in the range of 23.2 to 186 cells / cm ^2. The evaluation result of the heater was “A” even if the output density was about 5 times that of the conventional product.

(Example 3: Examination of combination of partition wall thickness and cell density of honeycomb structure in heater having power density about 10 times that of conventional product)
In the same manner as in Example 1, 12 types of heaters having different combinations of the partition wall thickness and cell density of the honeycomb structure portion were produced. However, these heaters are adjusted to have a power density about 10 times that of the conventional product by making the size of the honeycomb structure portion smaller than that of the second embodiment. The specific dimensions of the honeycomb structure part were such that the length of one side of the square on the end face of the honeycomb structure part was 41 mm, and the length of the honeycomb structure part in the cell extending direction was 25 mm.

  Using these 12 types of heaters, the input power, voltage, flow rate and fluid initial temperature are set as shown in Table 1, and the fluid (coolant as the medium to be heated) is heated, and the body temperature at the time of the heating And pressure loss were measured, and each heater was evaluated based on the measurement results. The specific evaluation method is the same as in the case of Example 1. The evaluation results are shown in Table 4.

As shown in Table 4, the heater in which the partition wall thickness of the honeycomb structure part is included in the range of 0.05 to 0.1 mm and the cell density is included in the range of 48 to 186 cells / cm ² Even if the output density was about 10 times that of the conventional product, the evaluation result was “A”.

(Example 4: Examination of specific resistance of honeycomb structure)
A plurality of heaters having the same shape and size of the honeycomb structure part, the thickness of the partition walls and the cell density, and different only in specific resistance were manufactured. The specific shape of the honeycomb structure portion in these heaters was a cylindrical shape having a square end face. The specific dimensions of the honeycomb structure in these heaters are such that the length of one side of the square on the end face of the honeycomb structure is 75 mm, and the length of the honeycomb structure in the cell extending direction is 40 mm. It was. Further, the partition wall thickness of the honeycomb structure portion was 4 mil (0.1 mm), and the cell density was 600 cpsi (93 cells / cm ² ). It has been confirmed in advance that the pressure loss of the heater having the honeycomb structure having such a structure satisfies the conditions shown in Table 1. The manufacturing method of these heaters is basically the same as in Example 1, but the specific resistance of each heater was adjusted to a different value by changing the amount of metal Si impregnation during firing of the honeycomb structure.

  Using a plurality of heaters that differ only in the specific resistance of the honeycomb structure part, the input power, voltage, flow rate, and fluid initial temperature are set as shown in Table 1 to heat the fluid (coolant that is the medium to be heated). The fluid temperature and the body temperature during the heating were measured.

  As a result, it was confirmed that the heater having the honeycomb structure having a specific resistance of 6.8 to 9.5 Ω · cm satisfies the conditions shown in Table 1 for the fluid temperature and the body temperature. In addition, by changing the thickness and cell density of the partition walls of the honeycomb structure to various values within a practical range considering pressure loss, heat generation density, etc., a plurality of heaters having different specific resistances were produced. The fluid temperature and the body temperature were measured. As a result, it was confirmed that the heater having a specific resistance of 4 to 25 Ω · cm can satisfy the conditions shown in Table 1 in terms of fluid temperature and enclosure temperature. On the other hand, the heater having a honeycomb structure having a specific resistance of less than 4 Ω · cm has a body temperature exceeding 100 ° C. and cannot satisfy the conditions shown in Table 1. Further, a heater having a honeycomb structure having a specific resistance exceeding 25 Ω · cm had a fluid temperature of less than 70 ° C., and could not satisfy the conditions shown in Table 1.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used as a heater (coolant heating type on-vehicle air conditioner heater) that is used by being mounted on an automobile for heating inside the vehicle using a coolant as a medium to be heated.

1: partition wall, 2: cell, 3: outer peripheral wall, 4: honeycomb structure part, 5: side face, 11: one end face, 12: other end face, 21: electrode part, 22: terminal part, 23: conductive joint Part, 100: heater.

Claims (2)

A tubular honeycomb structure having a partition wall defining a plurality of cells extending from one end face to the other end face as a flow path for coolant that is a medium to be heated, and a tubular honeycomb structure portion having an outer peripheral wall located at the outermost periphery, and the honeycomb structure A pair of electrode parts joined to the side surface of the part,
The honeycomb structure part is made of a material mainly composed of ceramics, and generates heat when energized,
The partition wall has a thickness of 0.05 to 0.5 mm;
The honeycomb structure has a cell density of 9.3 to 186 cells / cm ² ;
The specific resistance of the honeycomb structure part is 4 to 25 Ω · cm,
The ceramic is one kind of ceramic selected from the group consisting of Si-impregnated SiC, Si-bonded SiC, recrystallized SiC, reaction-sintered SiC, and sintered SiC.
An insulating layer having a dielectric breakdown strength of 10 to 1000 V / μm on the surface of the partition;
A heater used in automobiles for heating inside the car.   The heater according to claim 1, wherein an aperture ratio of the honeycomb structure part is 60 to 90%.

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