Heater and heating element

Abstract

To provide a heater and a heating member that are resistant to cracks in a cordierite base material and are highly reliable in environments with a large thermal fluctuation.SOLUTION: A heater 100 includes a first cordierite base material 10, a glass portion 20 provided on the first cordierite base material 10, and an electric heating portion 30 buried in the glass portion 20, and the glass portion 20 contains MgO, Al2O3, and SiO2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heater and a heating element. [Background technology]

[0002] There is an increasing demand for reducing harmful components (HC, NOx, and CO) in automobile exhaust. Purifying NOx emitted from diesel engines is a particularly important issue. A commonly known NOx purification method is the urea SCR system. In a urea SCR system, NH3, a NOx reducing agent, is produced through the thermal decomposition and hydrolysis of urea. To efficiently promote the thermal decomposition and hydrolysis of urea, efficient heating of the urea is essential. However, exhaust gas temperatures have been decreasing with improved engine efficiency, and the exhaust gas temperature remains low even immediately after engine start. At low exhaust gas temperatures, the decomposition reaction of urea injected into the exhaust gas is difficult to occur, resulting in insufficient production of NH3. Furthermore, when the injected urea impacts the inner wall of the exhaust pipe, if the temperature of the inner wall is low, the urea does not completely decompose into NH3, resulting in the accumulation of solid intermediate deposits. This can result in obstruction of the exhaust gas flow or the resulting NH3 being prevented from mixing with the exhaust gas due to changes in the exhaust gas flow. For this reason, heaters that can efficiently heat exhaust gases and maintain the inner wall surface of the exhaust pipe at a high temperature are being developed.

[0003] Furthermore, for electric vehicles (BEVs: Battery Electric Vehicles) and fuel cell vehicles (FCVs: Fuel Cell Vehicles), which do not have a heat source from an internal combustion engine, and plug-in hybrid vehicles (PHVs: Plug-in Hybrid Vehicles, PHEVs: Plug-in Hybrid Electrical Vehicles), which frequently shut off their internal combustion engines, the heating load affects driving distance, so improving heating efficiency is an important issue.For this reason, heaters that can efficiently heat specific spaces in a short amount of time, rather than heating the entire passenger compartment, are being developed.

[0004] Furthermore, in order to achieve carbon neutrality, progress is being made in the development of synthetic fuels obtained by synthesizing hydrogen produced by electrolysis of water with CO2 emitted from power plants and factories, but the synthetic fuel manufacturing process requires heating. If this manufacturing process is carried out in a location where factory waste heat can be supplied, a heat source can be easily secured, but if it is carried out in a location where no heat source is available, heating must be performed using electricity. It is preferable to generate electricity from renewable energy sources that do not emit CO2 during the manufacturing process, and there is also a demand for heaters with improved heating efficiency.

[0005] A heater in which a conductor is embedded in a substrate having a small heat capacity or a conductor is disposed between the substrates is one of the effective heating means for the various applications described above. For example, Patent Document 1 proposes a heater including a plate-shaped first heater substrate, a heating wire arranged in a parallel circuit on a first surface of the first heater substrate, electrodes connected to the heating wire for passing electricity through the heating wire, and a plate-shaped cover substrate covering the first surface of the first heater substrate, the heating wire, and the electrodes on the second surface side. In this heater, the first heater substrate and / or the cover substrate contain Si3N4 or Al2O3, and the heating wire contains at least one metal selected from the group consisting of WC, TiN, TaC, ZrN, MoSi2, Pt, Ru, and W.

[0006] Patent Document 2 proposes a heater that includes an insulating base made of alumina ceramics, silicon nitride ceramics, or the like, and a resistor embedded in the insulating base, the resistor including first conductive particles whose main component is tungsten and second conductive particles whose main component is molybdenum. Patent Document 3 proposes a mixer for an exhaust gas purification device that includes an outer cylinder made of insulating ceramic such as alumina, silicon nitride, or cordierite, insulating ceramic fins provided inside the outer cylinder, and an electric heating section embedded in at least a portion of the outer cylinder and / or fins. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-182890 [Patent Document 2] Patent No. 5748918 [Patent Document 3] Japanese Patent Publication No. 2020-197208 Summary of the Invention [Problem to be solved by the invention]

[0008] Heaters used in the above applications are required to be capable of heating quickly and efficiently, and to be highly reliable in environments where there are large thermal fluctuations. In the above prior art, silicon nitride (Si3N4) used in the heater substrate is approximately 3 g / cm 3 Silicon nitride is lightweight due to its low density of about 3×10 -6 It has a low thermal expansion coefficient of 1 / K, a high Young's modulus of about 300 GPa, and a high bending strength of about 800 MPa, ensuring high reliability even in environments with large thermal fluctuations. However, silicon nitride is expensive and requires a sintering temperature of 1700°C or higher, making it expensive to manufacture. Alumina (Al2O3) is an inexpensive material and a widely used representative ceramic, but its density is approximately 4g / cm 3 It is heavy because of its high density of about 8 × 10 -6 / K and a high Young's modulus of approximately 350 GPa. Therefore, in environments with large thermal fluctuations, thermal stress increases, making it difficult to ensure reliability.

[0009] On the other hand, cordierite has a density of about 2.5 g / cm 3 Cordierite is lightweight due to its low density of about 1.6 x 10 -6 / K and a low Young's modulus of approximately 150 GPa. Therefore, cordierite can minimize the generation of thermal stress even in environments with large thermal fluctuations, ensuring high reliability. However, when a conductor with a high thermal expansion coefficient is embedded in a cordierite substrate made of cordierite with a low thermal expansion coefficient, or when a conductor is arranged between the cordierite substrates, there is a problem that cracks may occur in the cordierite substrate due to the difference in thermal expansion coefficients.

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a heater and a heating element in which cracks are less likely to occur in the cordierite substrate and which are highly reliable in environments with large thermal fluctuations. [Means for solving the problem]

[0011] As a result of intensive research, the inventors have discovered that by embedding an electric heating part (conductor) in a glass part and providing it in a cordierite substrate, it is possible to suppress the occurrence of cracks in the cordierite substrate caused by the difference in thermal expansion coefficient between the cordierite substrate and the electric heating part, and have thus completed the present invention.

[0012] That is, the present invention provides a heating element comprising a first cordierite substrate, a glass portion provided on the first cordierite substrate, and an electric heating portion embedded in the glass portion, The glass portion contains MgO, Al2O3 and SiO2. fruit, The first cordierite substrate is composed of 90% by mass or more of a cordierite phase, 5% by mass or less of a crystalline phase containing mullite and / or spinel, and the remainder being a glass phase. It's a heater.

[0013] The present invention also provides a cylindrical member, the heater disposed along at least a portion of an inner circumferential surface of the cylindrical member; an insulating material disposed between the cylindrical member and the heater; Equipped with The electric heating portions of the plurality of heaters are heating elements that can be electrically connected to a power source in series or in parallel. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a heater and a heating element that are less likely to cause cracks in the cordierite substrate and are highly reliable in environments with large thermal fluctuations. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a top view of a heater according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA' in FIG. [Figure 3] FIG. 10 is a top view of a heater according to another embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view taken along the line BB′ in FIG. 3. [Figure 5] FIG. 2 is a cross-sectional view of a heating member according to an embodiment of the present invention. [Figure 6] 1 is a top view showing a state in which electric heating portions of a plurality of heaters according to an embodiment of the present invention are electrically connected in series to a power source. [Figure 7] FIG. 2 is a top view showing a state in which the electric heating portions of a plurality of heaters according to the embodiment of the present invention are electrically connected in parallel to a power source. [Figure 8] 1 is a cross-sectional view of a heating element according to an embodiment of the present invention used to heat a reducing agent precursor to produce a reducing agent. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention are also within the scope of the present invention.

[0017] (1) Heater FIG. 1 is a top view of a heater according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the heater taken along line AA'. As shown in FIGS. 1 and 2 , the heater 100 includes a first cordierite substrate 10, a glass portion 20 provided on the first cordierite substrate 10, and an electric heating portion 30 embedded in the glass portion 20. In FIG. 1 , the dotted line indicates the position of the electric heating portion 30 embedded in the glass portion 20. Since the glass portion 20 has a thermal expansion coefficient similar to that of the first cordierite substrate 10, the electric heating portion 30 is embedded in the glass portion 20 and provided on the first cordierite substrate 10, and cracks in the first cordierite substrate 10 can be suppressed by preventing direct contact between the first cordierite substrate 10 and the electric heating portion 30. Therefore, the reliability of the heater 100 can be improved in environments with large thermal fluctuations.

[0018] The first cordierite substrate 10 is a substrate containing cordierite (2MgO·2Al2O3·5SiO2) as a main component. In this specification, the term "main component" means a component that accounts for more than 50% by mass, preferably 90% by mass or more of all components. The first cordierite substrate 10 preferably comprises 90% by mass or more of a cordierite phase, 5% by mass or less of a crystalline phase containing mullite and / or spinel, and the remainder of a glass phase. With this composition, properties such as the thermal expansion coefficient and Young's modulus can be controlled within desired ranges. Here, the mass % of each phase in the first cordierite substrate 10 is determined as follows. First, a plurality of samples are prepared by mixing cordierite, mullite, spinel, and glass at different mass ratios, and a calibration curve of X-ray diffraction peak values ​​is created in advance. Next, the peak values ​​are determined by X-ray diffraction of the first cordierite substrate 10, and the mass ratio (mass %) of each phase in the first cordierite substrate 10 is determined based on the calibration curve.

[0019] The open porosity of the first cordierite substrate 10 is not particularly limited, but is preferably 10% or less, and more preferably 5% or less. By controlling the open porosity within this range, when the heater 100 is used in an environment where a liquid such as a reducing agent precursor (e.g., urea water) adheres, the liquid can be made less likely to penetrate into the inside of the first cordierite substrate 10. The open porosity of the first cordierite substrate 10 can be measured using an existing test method (Archimedes method, JIS R1634:1998). The open porosity of the first cordierite substrate 10 can be controlled by reducing the particle size of the raw material powder or by adding a sintering aid or the like.

[0020] The thermal expansion coefficient of the first cordierite substrate 10 is not particularly limited, but is preferably 1.5×10 -6 ~2.0×10 -6 / K. If the thermal expansion coefficient is in this range, the thermal stress in an environment with large thermal fluctuations can be reduced, and the reliability of the heater 100 is improved. The thermal expansion coefficient of the first cordierite substrate 10 can be measured in accordance with JIS R1618:2002.

[0021] The Young's modulus of the first cordierite substrate 10 is not particularly limited, but is preferably 160 GPa or less. A Young's modulus in this range can reduce thermal stress in an environment with large thermal fluctuations, thereby improving the reliability of the heater 100. In addition, the Young's modulus of the first cordierite substrate 10 is preferably 100 GPa or more from the viewpoint of suppressing deformation or damage of the heater 100 due to vibration. Here, the Young's modulus of the first cordierite substrate 10 can be calculated as follows. The bending strength of the first cordierite substrate 10 is measured in accordance with the four-point bending strength test method specified in JIS R1601:2008, and a "stress-strain curve" is created from the measurement results. The slope of the "stress-strain curve" thus obtained is calculated, and the slope of this "stress-strain curve" is defined as the Young's modulus.

[0022] The glass portion 20 contains MgO, Al2O3, and SiO2. Since MgO, Al2O3, and SiO2 are components of cordierite, the glass portion 20 containing MgO, Al2O3, and SiO2 can reduce the difference in thermal expansion coefficient between the glass portion 20 and the first cordierite substrate 10. As a result, thermal stress in an environment with large thermal fluctuations can be reduced, improving the reliability of the heater 100. In addition, the adhesion between the glass portion 20 and the first cordierite substrate 10 can also be improved.

[0023] The glass portion 20 can contain cordierite (2MgO·2Al2O3·5SiO2). By including cordierite in the glass portion 20, the thermal expansion coefficient of the glass portion 20 can be made closer to that of the first cordierite substrate 10. As a result, thermal stress in an environment with large thermal fluctuations can be reduced, improving the reliability of the heater 100. In addition, the adhesion of the glass portion 20 to the first cordierite substrate 10 can also be improved. The method for incorporating cordierite into the glass portion 20 is not particularly limited, but for example, waste materials generated during the production of the first cordierite substrate 10 may be added to the raw materials of the glass portion 20 .

[0024] The glass portion 20 is preferably composed of 30 to 40 mass % of a cordierite phase, 2 mass % or less of a crystalline phase containing mullite and / or spinel, and the remainder of a glass phase. With such a composition, properties such as the thermal expansion coefficient can be controlled within a desired range. The mass % of each phase in the glass portion 20 is determined as follows. First, multiple samples are prepared by mixing cordierite, mullite, spinel, and glass at different mass ratios, and a calibration curve of X-ray diffraction peak values ​​is created in advance. Next, the peak values ​​are determined by X-ray diffraction of the glass portion 20, and the mass ratio (mass %) of each phase in the glass portion 20 is determined based on the calibration curve.

[0025] The thermal expansion coefficient of the glass portion 20 is not particularly limited, but is preferably 1.6×10 -6 / K exceeded 3.0×10 -6 / K, more preferably less than 1.6 × 10 -6 / K excess 2.5×10 -6 / K or less, more preferably 1.6 × 10 -6 / K excess 2.0×10 -6 / K or less. If the thermal expansion coefficient of the glass portion 20 is within the above range, it is possible to reduce the difference in the thermal expansion coefficient between the glass portion 20 and the first cordierite substrate 10. As a result, it is possible to reduce thermal stress in an environment with large thermal fluctuations, thereby improving the reliability of the heater 100.

[0026] The electric heating part 30 is composed of a conductor that generates heat when electricity is passed through it. There are no particular limitations on the conductor, and any metal or alloy known in the art can be used. Among these, it is preferable that the conductor contains Mo and / or W. By using such a conductor, it is possible to reduce the difference in thermal expansion coefficient between the electric heating part 30 and the glass part 20 and also improve the affinity with the glass part 20 in which it is embedded. Other usable conductors include Ni-Cr alloys and Fe-Cr-Al alloys.

[0027] The thermal expansion coefficient of the electric heating part 30 is not particularly limited, but is preferably 1.6×10 -6 / K excess 6.0×10 -6 / K, more preferably less than 1.6 × 10 -6 / K excess 5.5×10 -6 / K or less. If the thermal expansion coefficient of the electric heating part 30 is in the above range, the difference in the thermal expansion coefficient between the electric heating part 30 and the glass part 20 can be reduced. As a result, the thermal stress in an environment with large thermal fluctuations can be reduced, improving the reliability of the heater 100. For example, Mo has a thermal expansion coefficient of about 5.0×10 -6 The thermal expansion coefficient of the electric heating part 30 can also be controlled by using a conductive composite made by combining Mo powder and / or W powder with low thermal expansion glass powder and adjusting the proportions and types of each component.

[0028] The shape of the electric heating part 30 is not particularly limited, and can be various shapes such as a line shape, a plate shape, a sheet shape, etc. Note that Figures 1 and 2 show an example in which the electric heating part 30 is formed in a line shape.

[0029] A second cordierite substrate may further be provided on the glass portion 20 in which the electric heating portion 30 is embedded. Here, a top view of a heater further including a second cordierite substrate is shown in FIG. 3, and a cross-sectional view of this heater taken along line BB' is shown in FIG. As shown in FIGS. 3 and 4 , the heater 200 includes a first cordierite substrate 10, a glass portion 20 provided on the first cordierite substrate 10, an electric heating portion 30 embedded in the glass portion 20, and a second cordierite substrate 40 provided on the glass portion 20. In FIG. 4 , the dotted line indicates the position of the electric heating portion 30 embedded in the glass portion 20. In the heater 200 having such a structure, the electric heating portion 30 is embedded in the glass portion 20 and provided between the first cordierite substrate 10 and the second cordierite substrate 40, preventing direct contact between the first cordierite substrate 10 and the second cordierite substrate 40 and the electric heating portion 30. This can suppress cracks in the first cordierite substrate 10 and the second cordierite substrate 40. This can improve the reliability of the heater 200 in environments with large thermal fluctuations.

[0030] The second cordierite substrate 40 is a substrate containing cordierite (2MgO·2Al2O3·5SiO2) as a main component, similar to the first cordierite substrate 10, and the same material as the first cordierite substrate 10 can be used. The second cordierite substrate 40 preferably comprises 90% by mass or more of a cordierite phase, 5% by mass or less of a crystalline phase containing mullite and / or spinel, and the remainder being a glass phase. With such a composition, properties such as the thermal expansion coefficient and Young's modulus can be controlled within desired ranges. The mass percentage of each phase in the second cordierite substrate 40 can be determined in the same manner as the mass percentage of each phase in the first cordierite substrate 10.

[0031] 1 to 4, the heaters 100, 200 may further include terminals 50 connected to the electric heating unit 30 by brazing material 60. This configuration makes it easy to electrically connect the electric heating unit 30 to an external power source (not shown).

[0032] The terminal 50 is made of a conductive material. The conductor used for the terminal 50 is not particularly limited, and any metal or alloy known in the art can be used. Among them, the conductor used for the terminal 50 preferably contains Fe, Ni, and Co. Kovar, for example, can be used as such a material. The conductor used for the terminal 50 may be made of the same conductor as the electric heating section 30 or may be made of a conductor different from that of the electric heating section 30.

[0033] The thermal expansion coefficient of the conductor constituting the terminal 50 is not particularly limited, but is preferably 1.6×10 -6 / K excess 6.0×10 -6 / K, more preferably less than 3.0 × 10 -6 / K excess 6.0×10 -6 / K. If the thermal expansion coefficient of the conductor constituting the terminal 50 is within the above range, the difference in the thermal expansion coefficient between the second cordierite substrate 40 and the conductor constituting the terminal 50 can be reduced, particularly in the heater 200 shown in Figs. 3 and 4. As a result, thermal stress in an environment with large thermal fluctuations can be reduced, improving the reliability of the heater 200. For example, Kovar has a thermal expansion coefficient of about 5.0 x 10 -6 / K.

[0034] 3 and 4, the terminals 50 are preferably inserted into through holes formed in the second cordierite substrate 40. This configuration makes it easy to electrically connect the electric heating unit 30 to an external power source (not shown).

[0035] The brazing filler metal 60 is a material that joins the electric heating part 30 and the terminal 50. There are no particular limitations on the brazing filler metal 60, and an appropriate material may be selected depending on the type of electric heating part 30 and terminal 50. For example, when a conductor containing Mo and / or W is used for the electric heating part 30 and a conductor containing Fe, Ni, and Co is used for the terminal 50, the brazing filler metal 60 preferably contains Ag, Ti, and Cu. A brazing filler metal 60 containing these components can appropriately join the electric heating part 30 and the terminal 50 without affecting them.

[0036] Here, an experiment was conducted in which a conductor made of Mo (Mo wire) was used for the heating part 30 and a conductor made of Kovar (Kovar pin) was used for the terminal 50, and three types of brazing filler metals 60 (66Ag-8Ti-Cu, 65Ag-15Pd-Cu, and Ni-Cr-P) were used to actually join the heating part 30 and the terminal 50. The results showed that 66Ag-8Ti-Cu successfully joined the Mo wire and the Kovar pin at approximately 900°C. In contrast, when 65Ag-15Pd-Cu was used to join the Mo wire and the Kovar pin at 900°C, evaporation of Pd was confirmed. Furthermore, reaction with the Mo wire was confirmed with Ni-Cr-P. Therefore, when using Mo wire for the heating part 30 and Kovar pin for the terminal 50, 66Ag-8Ti-Cu is the most suitable brazing filler metal 60.

[0037] As shown in FIGS. 1 to 4 , the heaters 100 and 200 can further include a seal portion 70 provided on the boundary surface between the terminal 50 and the glass portion 20 or the second cordierite substrate 40. Specifically, the heater 100 can include the seal portion 70 on the boundary surface between the terminal 50 and the glass portion 20. The heater 200 can also include the seal portion 70 on the boundary surface between the terminal 50 and the second cordierite substrate 40. Such a configuration can prevent liquid, air, and the like from entering through the boundary, thereby improving the reliability of the heaters 100 and 200.

[0038] There are no particular limitations on the material that constitutes the seal portion 70, and any sealing material known in the art can be used. Among these, the material that constitutes the seal portion 70 is preferably glass. Furthermore, the sealing portion 70 (glass) preferably contains SiO2 and B2O3. The sealing portion 70 containing such components has a small thermal expansion coefficient, which can suppress cracks in the sealing portion 70 and its surrounding members (the glass portion 20 and the second cordierite substrate 40).

[0039] The thermal expansion coefficient of the glass constituting the seal portion 70 is not particularly limited, but is preferably 1.6×10 -6 / K excess 6.0×10 -6 / K, more preferably less than 2.0 × 10 -6 / K exceeded 4.0×10 -6 / K. If the thermal expansion coefficient of the glass constituting the seal portion 70 is within the above range, in the heater 100, the difference in thermal expansion coefficient between the glass portion 20 and the conductor constituting the terminal 50 and the glass constituting the seal portion 70 becomes small, and in the heater 200, the difference in thermal expansion coefficient between the second cordierite substrate 40 and the conductor constituting the terminal 50 and the glass constituting the seal portion 70 becomes small. As a result, thermal stress in an environment with large thermal fluctuations can be reduced, improving the reliability of the heaters 100 and 200.

[0040] By configuring the heaters 100, 200 as described above, cracks are less likely to occur in the cordierite substrate (the first cordierite substrate 10 and the second cordierite substrate 40) and the heaters 100, 200 are highly reliable in environments with large thermal fluctuations, and therefore can be used for a variety of purposes. For example, the heaters 100 and 200 are useful in a urea SCR system for a diesel engine for heating exhaust gas in an exhaust gas mixer that mixes urea with exhaust gas. They are also useful in this urea SCR system for maintaining a high temperature on the inner wall surface of the cylindrical member (exhaust pipe) that constitutes the exhaust gas mixer, thereby preventing urea from accumulating as a solid deposit when it collides with the inner wall surface. In a urea SCR system, ammonia (NH3), which serves as a NOx reducing agent, can be produced by injecting urea water into exhaust gas heated by the heaters 100 and 200. The heaters 100 and 200 are also useful for use in heating equipment in electric vehicles, fuel cell vehicles, and plug-in hybrid cars, and as heating means in the synthetic fuel production process.

[0041] The heaters 100 and 200 can be manufactured according to methods known in the art. For example, the heater 100 can be manufactured as follows. First, a molding material containing cordierite raw material powder is molded and then sintered to produce the first cordierite substrate 10. The molding method is not particularly limited, and extrusion molding, mold casting, or the like can be used. Alternatively, the first cordierite substrate 10 may be produced by machining a sintered body having a predetermined shape. Next, the electric heating part 30 is sandwiched between two glass sheets that will become the glass part 20, and the laminated structure is placed on the first cordierite substrate 10. At this time, an opening is provided in the glass sheet on the front side to connect the electric heating part 30 and the terminal 50 with the brazing material 60. Next, the laminated structure is integrated by heating and pressurizing treatment. At this time, the glass sheets are integrated to form the glass part 20, and the electric heating part 30 is embedded in the glass part 20. The conditions for heating and pressurizing are not particularly limited and may be set appropriately depending on the type of glass sheet used. Next, the terminals 50 are placed on the electric heating parts 30 exposed at the openings of the front-side glass sheet via the brazing filler metal 60, and are bonded by heat treatment. The heating conditions may be appropriately set depending on the type of brazing filler metal 60 used, and are not particularly limited. Finally, a sealant is applied to the surface of glass portion 20 at the boundary between terminal 50 and glass portion 20, and then heat treatment is performed to form seal portion 70, completing heater 100. The heating conditions are not particularly limited and may be set appropriately depending on the type of sealant used.

[0042] The heater 200 can be manufactured as follows. First, a molding material containing cordierite raw material powder is molded and then sintered to produce the first cordierite substrate 10 and the second cordierite substrate 40 . Next, the electric heating part 30 is sandwiched between two glass sheets that will become the glass part 20, and this is arranged between the first cordierite substrate 10 and the second cordierite substrate 40 to form a laminated structure. At this time, openings for connecting the electric heating part 30 and the terminal 50 with the brazing material 60 are provided in the second cordierite substrate 40 and the glass sheet on the side of the second cordierite substrate 40. Next, in order to improve the adhesion between the first cordierite substrate 10, the second cordierite substrate 40, and the glass sheet sandwiching the electric heating portion 30, the laminated structure is integrated by heat treatment while applying pressure. Next, a terminal 50 is placed on the second cordierite substrate 40 and the electric heating portion 30 exposed at the opening of the glass sheet on the second cordierite substrate 40 side via a brazing material 60, and bonded by heat treatment. Finally, a sealant is applied to the surface of the second cordierite base material 40 at the boundary between the terminal 50 and the second cordierite base material 40, and then heat treatment is performed to form a seal portion 70, thereby completing the heater 200.

[0043] (2) Heating element 5 is a cross-sectional view of a heating member according to an embodiment of the present invention, taken along a direction perpendicular to the axial direction of a cylindrical member 300 constituting the heating member 1000. 5, the heating member 1000 includes a cylindrical member 300, a plurality of heaters 100, 200 arranged along at least a portion of the inner circumferential surface of the cylindrical member 300, and an insulating material 400 arranged between the cylindrical member 300 and the heaters 100, 200. With this structure, it becomes possible to heat the inside of the cylindrical member 300.

[0044] The cylindrical member 300 is not particularly limited, and may have a uniform diameter in the axial direction, or may have a diameter that decreases and / or increases in the axial direction. The material of the cylindrical member 300 is not particularly limited, but is preferably a metal from the viewpoint of manufacturability. Examples of metals that can be used include stainless steel, titanium alloys, copper alloys, aluminum alloys, and brass. Among these, stainless steel is preferred because of its high durability, reliability, and low cost.

[0045] The thickness of the cylindrical member 300 is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more. By making the thickness of the cylindrical member 300 0.1 mm or more, durability and reliability can be ensured. Furthermore, the thickness of the cylindrical member 300 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. By making the thickness of the cylindrical member 300 10 mm or less, weight reduction can be achieved.

[0046] The insulating material 400 is not particularly limited, and a fiber mat made of silicon nitride, alumina, or the like can be used. The thickness of the insulating material 400 is not particularly limited as long as it is thick enough to ensure insulation.

[0047] The heaters 100, 200 are arranged along at least a portion of the inner circumferential surface of the cylindrical member 300. The method for fixing the heaters 100, 200 is not particularly limited, but may be, for example, fixed to the inner circumferential surface of the cylindrical member 300 using a fixing jig such as a bolt 500.

[0048] The heaters 100, 200 are configured so that the electric heating units 30 can be electrically connected to a power source in series or parallel. With this configuration, when a voltage is applied from the power source, the heaters 100, 200 generate heat, and the inside of the cylindrical member 300 can be heated. Here, Fig. 6 shows a top view illustrating a state in which the electric heating parts 30 of the multiple heaters 100, 200 are electrically connected in series to a power source. Fig. 7 shows a top view illustrating a state in which the electric heating parts 30 of the multiple heaters 100, 200 are electrically connected in parallel to a power source. Note that Figs. 6 and 7 show three heaters 100 in a planar view to make it easier to understand. Dotted lines indicate the positions of the embedded electric heating parts 30. In Fig. 6, the electric heating parts 30 of the multiple heaters 100, 200 are electrically connected in series, with one end of the series-connected electric heating parts 30 electrically connected to a power source and the other end electrically connected to earth (for example, a cylindrical member 300). In Fig. 7, the electric heating parts 30 of the multiple heaters 100, 200 are electrically connected in parallel, with one end of each electric heating part 30 electrically connected to a power source and the other end electrically connected to earth (for example, a cylindrical member 300).

[0049] The voltage applied from the power supply is not particularly limited, but is preferably 60 V or less. A voltage in this range does not require special insulation. Furthermore, considering the heating efficiency of the heaters 100 and 200, the applied voltage is preferably 12 V or more.

[0050] The heating member according to the embodiment of the present invention is suitable for use in a urea SCR system of a diesel engine. That is, the heating member according to the embodiment of the present invention can be used to generate a reducing agent (e.g., ammonia) by heating the reducing agent precursor while maintaining a high temperature on the inner wall surface of the cylindrical member 300 that constitutes an exhaust gas mixer that mixes a reducing agent precursor (e.g., urea water) with exhaust gas and suppressing the accumulation of an intermediate solid deposit when the reducing agent precursor collides with the inner wall surface.

[0051] A cross-sectional view of a heating member used to generate a reducing agent by heating a reducing agent precursor is shown in Fig. 8. Fig. 8 is a cross-sectional view taken in a direction perpendicular to the axial direction of a cylindrical member 300 constituting the heating member 2000. As shown in FIG. 8 , the heating element 2000 is disposed on at least a portion of the cylindrical element 300 and further includes a nozzle 600 capable of injecting a reducing agent precursor onto the inner circumferential surface of the cylindrical element 300. Furthermore, the plurality of heaters 100, 200 are disposed on the inner circumferential surface of the cylindrical element 300 from which the reducing agent precursor is injected from the nozzle 600. Furthermore, the cylindrical element 300 is an exhaust pipe of a diesel engine. With this configuration, the exhaust gas flowing through the cylindrical element 300 (exhaust pipe) can be heated by the plurality of heaters 100, 200, and the reducing agent can be generated by injecting the reducing agent precursor into the heated exhaust gas. Furthermore, even if the reducing agent precursor injected from the nozzle 600 collides with the plurality of heaters 100, 200, the reducing agent precursor quickly evaporates, thereby suppressing the accumulation of deposits that would otherwise be generated by decomposition of the reducing agent precursor.

[0052] In the heating element 2000, it is preferable that the electric heating portions 30 of the plurality of heaters 100, 200 are electrically connected in parallel. That is, it is preferable that one end of the electric heating portions 30 of the plurality of heaters 100, 200 is electrically connected to a power source, and the other end is electrically connected to a ground (for example, the cylindrical member 300). It is also preferable that the voltage applied from the power source is 60 V or less. With this configuration, it is possible to quickly and efficiently heat the reducing agent precursor to generate the reducing agent, and to suppress the deposition of intermediates on the inner wall surface of the cylindrical member 300. [Explanation of symbols]

[0053] 10 First cordierite substrate 20 Glass section 30 Electric heating section 40 Second cordierite substrate 50 terminals 60 Brazing filler metal 70 Seal part 100,200 heater 300 Cylindrical member 400 Insulation 500 volts 600 nozzles 1000,2000 Heating element

Claims

1. A first cordierite substrate, a glass portion provided on the first cordierite substrate, and an electric heating portion embedded in the glass portion, The glass portion is made of MgO and Al 2 O 3 and SiO 2 Including, The heater, wherein the first cordierite substrate is composed of 90% by mass or more of a cordierite phase, 5% by mass or less of a crystalline phase containing mullite and / or spinel, and the remainder being a glass phase.

2. The heater of claim 1 , further comprising a second cordierite substrate disposed on the glass portion.

3. The heater according to claim 1 or 2, further comprising a terminal connected to the electric heating portion by brazing material.

4. The heater according to claim 3 , wherein the terminal is inserted into a through-hole provided in the second cordierite substrate.

5. The heater according to claim 3 or 4, further comprising a seal portion provided at a boundary surface between the terminal and the glass portion or the second cordierite substrate.

6. The heater according to any one of claims 1 to 5, wherein the glass portion contains cordierite.

7. The heater according to any one of claims 1 to 6, wherein the glass portion is composed of 30 to 40 mass% of a cordierite phase, 2 mass% or less of a crystalline phase containing mullite and / or spinel, and the remainder being a glass phase.

8. A heater described in any one of claims 2 to 7, wherein the second cordierite substrate is composed of 90% by mass or more of a cordierite phase, 5% by mass or less of a crystalline phase containing mullite and / or spinel, and the remainder being a glass phase.

9. The thermal expansion coefficient of the glass portion is 1.6×10 -6 / K excess 3.0×10 -6 The heater according to any one of claims 1 to 8, wherein the temperature is less than 100°C / K.

10. The heater according to any one of claims 1 to 9, wherein the electric heating portion is made of a conductor containing Mo and / or W.

11. The terminal has a thermal expansion coefficient of 1.6×10 -6 / K excess 6.0×10 -6 The heater according to any one of claims 3 to 10, which is made of a conductor having a resistance of less than 1 / K.

12. The thermal expansion coefficient of the conductor constituting the terminal is 3.0×10 -6 / K excess 6.0×10 -6 12. The heater of claim 11, wherein the temperature is less than 1 / K.

13. The sealing portion has a thermal expansion coefficient of 1.6×10 -6 / K excess 6.0×10 -6 The heater according to any one of claims 5 to 12, which is made of glass having a viscosity of less than 1 / K.

14. The thermal expansion coefficient of the glass constituting the sealing portion is 2.0×10 -6 / K exceeded 4.0×10 -6 14. The heater of claim 13, wherein the temperature is less than 1 / K.

15. The heater according to any one of claims 3 to 14, wherein the terminals contain Fe, Ni and Co.

16. The sealing portion is made of SiO 2 and B 2 O 3 The heater according to any one of claims 5 to 15, comprising:

17. The heater according to any one of claims 3 to 16, wherein the brazing material contains Ag, Ti and Cu.

18. The heater according to any one of claims 1 to 17, which is used to heat exhaust gas.

19. A cylindrical member; A plurality of heaters according to any one of claims 1 to 18, which are arranged along at least a part of an inner circumferential surface of the cylindrical member; an insulating material disposed between the cylindrical member and the heater; Equipped with A heating member in which the electric heating portions of the plurality of heaters are electrically connectable to a power source in series or in parallel.

20. 20. The heating element according to claim 19, which is used to heat a reducing agent precursor to generate a reducing agent, a nozzle disposed at least in a portion of the cylindrical member and capable of injecting the reducing agent precursor onto an inner circumferential surface of the cylindrical member; the heater is disposed on an inner circumferential surface of the cylindrical member from which the reducing agent precursor is injected from the nozzle, The heating element, wherein the cylindrical member is an exhaust pipe of a diesel engine.

21. One end of the electric heating portion of the heater is electrically connected to the power source, and the other end is electrically connected to the cylindrical member, 21. The heating element of claim 20, wherein the applied voltage from the power supply is 60 V or less.

Images