Heating device and heating element

Abstract

A heating device 100 comprising: a first ceramic substrate 10; a glass portion 20 provided on the first ceramic substrate 10; and an electrically heating portion 30 embedded in the glass portion 20. The glass portion 20 has closed pores 21. The electrically heating portion 30 comprises a metal, wherein a rate of change of a mass at 700°C relative to a mass at 25°C in the air atmosphere is 0.1% or less.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a heating device and a heating element. BACKGROUND OF THE INVENTION

[0002] There is a growing demand for the reduction of harmful components (HC, NOx, CO) in motor vehicle exhaust gases. In particular, the purification of NOx emitted by diesel engines is an important problem. A technology called urea SCR system is widely known in the art as a measure for NOx removal. In the urea SCR system, the thermal decomposition and hydrolysis of urea produce NH 3, which is a NOx reducing agent. Efficient heating of urea is required for efficient thermal decomposition and hydrolysis of urea. However, with the improvement of engine efficiency, the temperature of the exhaust gas has been lowered, and the temperature of the exhaust gas is also lower immediately after the engine is started. When the temperature of the exhaust gas is lower, the decomposition reaction does not easily occur even if urea is injected into the exhaust gas, so NH 3 is not sufficiently generated. When the injected urea collides with an inner wall surface of an exhaust pipe, a lower temperature of the inner wall surface does not completely decompose the urea into NH 3 , so that the urea is converted into a solid intermediate deposit that accumulates. As a result, it becomes an obstacle to the flow of exhaust gas or prevents the mixing of the produced NH 3and the exhaust gas due to a change in the flow of the exhaust gas. Therefore, heating devices have been developed that can efficiently heat the exhaust gas and maintain the inner wall surface of the exhaust pipe at a high temperature.

[0003] Furthermore, in battery electric vehicles (BEVs) and fuel cell vehicles (FCVs), which lack a heat source from the internal combustion engine, and plug-in hybrid vehicles (PHVs) (plug-in hybrid electrical vehicles, PHEVs) that frequently stop the internal combustion engine, increasing heating efficiency is an important issue because heating load affects driving distance. Therefore, heating devices are being developed that can efficiently heat only a specific space in a short period of time, rather than heating the entire vehicle interior.

[0004] Furthermore, in order to achieve carbon neutrality, the development of synthetic fuels obtained by synthesizing hydrogen produced by the electrolysis of water and CO 2 emitted by power plants and factories, but heating is required for the synthetic fuel production process. If this production process is carried out in a location where it is possible to supply factory waste heat or the like, the heat source can be easily secured, but if it is carried out in a location where there is no heat source, it must be heated using electricity. The electricity is preferably generated from renewable energy that does not emit CO during the production process. 2 emitted, so the heating device must also have improved heating efficiency.

[0005] A heating device in which conductors are embedded in substrates with a low heat capacity or the conductor is arranged between the substrates is one of the effective heating means described above for various applications.

[0006] For example, Patent Literature 1 proposes a heater comprising: a plate-shaped first heater substrate; a heating wire arranged in a parallel circuit on a first surface of the first heater substrate; an electrode connected to the heating wire to supply power to the heating wire; and a plate-shaped cover substrate for covering the first surface of the first heater substrate, the heating wire, and the electrode on a second surface side. In this heater, the first heater substrate and / or the cover substrate contain Si 3 N 4 or Al 2 O 3, and the heating wire contains at least one metal selected from the group consisting of WC, TiN, TaC, ZrN, MoSi 2 , Pt, Ru and W.

[0007] Patent Literature 2 proposes a heating device comprising: an insulating substrate made of alumina ceramics, silicon nitride ceramics, or the like; and a resistor embedded in the insulating substrate, the resistor containing first conductive particles mainly based on tungsten and second conductive particles mainly based on molybdenum.

[0008] Patent Literature 3 proposes a mixer for exhaust gas purification devices, comprising: an outer cylinder made of insulating ceramics such as alumina, silicon nitride, and cordierite; fins made of insulating ceramics provided inside the outer cylinder; and an electrically heating portion embedded in at least a part of the outer cylinder and / or the fins. STATE OF THE ARTPatent literature [Patent Literature 1] Japanese Patent Application Publication No. 2017-182890 A [Patent Literature 2] Japanese Patent Application No. 5748918 B [Patent Literature 3] Japanese Patent Application Publication No. 2020-197208 A SUMMARY OF THE INVENTION TASK TO BE SOLVED BY THE INVENTION

[0009] Heating devices used for the applications described above must be able to heat quickly and efficiently and must be durable in harsh environments (especially environments requiring corrosion resistance, heat resistance, impact resistance, insulation, etc.).

[0010] However, for the heaters described in the above-described prior art, it is difficult to be durable in harsh environments depending on the types of substrates and conductors. For example, since an alumina substrate has a high thermal expansion coefficient, it is difficult to be durable in environments with large temperature changes because thermal stress increases. Furthermore, although a cordierite substrate has a low thermal expansion coefficient, when a conductor with a high thermal expansion coefficient is embedded in the cordierite substrate or a conductor is arranged between the cordierite substrates, cracks are easily generated in the cordierite substrate due to a difference in thermal expansion coefficient in environments with large temperature changes, so it is difficult to be durable. Furthermore, conductors such as aluminum oxide substrates are often used in harsh environments.Molybdenum and tungsten, easily oxidized when exposed to elevated temperature in the presence of a small amount of air, and as the oxidation progresses, there is a risk of eventual separation, so it is difficult to be durable.

[0011] The present invention is designed to solve the above-mentioned problems. An object of the present invention is to provide a heating device and a heating element that are durable even in harsh environments. MEANS TO SOLVE THE PROBLEM

[0012] As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by embedding a specific electrically heating portion (conductor) in a glass portion having closed pores to provide it in a ceramic substrate, and they have completed the present invention. [1] A heating device comprising: a first ceramic substrate; a glass portion provided on the first ceramic substrate; and an electrically heating portion embedded in the glass portion, wherein the glass portion has closed pores, and wherein the electrically heating portion comprises a metal, wherein a change rate of a mass at 700 °C relative to a mass at 25 °C in the air atmosphere is 0.1% or less. [2] The heating device according to [1], further comprising a second ceramic substrate provided on the glass portion. [3] Heating device according to [1] or [2], wherein the ceramic substrate is a cordierite substrate. [4] Heating device according to one of [1] to [3], wherein the glass portion has a thermal expansion coefficient of less than 6.0 × 10 -6 / K. [5] Heating device according to one of [1] to [4], wherein the glass portion has a modulus of elasticity of 5 to 50 GPa. [6] Heating device according to one of [1] to [5], wherein the glass portion comprises boron and / or silicon and has a glass transition temperature of 600 to 1100 °C. [7] The heating device according to any one of [1] to [6], wherein the electrically heating portion has a change rate of a volume resistivity at 300 °C relative to a volume resistivity at 25 °C of 10% or less. [8] A heating device according to any one of [1] to [7], wherein the electrically heating portion comprises an alloy containing one or more selected from Ni, Fe and Cr. [9] Heating device according to [8], wherein the alloy is a Ni-Cr alloy or a Fe-Cr alloy.

[10] The heating device according to any one of [1] to [9], further comprising a terminal connected to the electrically heating portion.

[11] Heating device according to

[10] , wherein the terminal is connected to the electrically heating section via a brazing material.

[12] Heating device according to one of [1] to

[11] , wherein the heating device is used for heating an exhaust gas.

[13] Heating element comprising: a cylindrical element; the heating devices according to any one of [1] to

[12] , wherein each of the heating devices is arranged along an inner peripheral surface of at least a part of the cylindrical member; and an insulating material disposed between the cylindrical member and each of the heating devices; wherein the electrical heating sections of the heating devices can be electrically connected to a power source in series or parallel.

[14] Heating element according to

[13] , which is used for heating a reducing agent precursor to produce a reducing agent, wherein the heating element further comprises a nozzle capable of injecting the reducing agent precursor onto an inner peripheral surface of the cylindrical member, the nozzle being arranged on at least a portion of the cylindrical member, wherein each of the heating devices is arranged on the inner peripheral surface of the cylindrical member onto which the reducing agent precursor is injected through the nozzle, and wherein the cylindrical element is an exhaust pipe for a diesel engine.

[15] Heating element according to

[14] , wherein each of the electric heating sections of the heating devices has one end electrically connected to the power source and the other end electrically connected to the cylindrical member, and where a voltage applied by the power source is 80 V or less. EFFECTS OF THE INVENTION

[0013] According to the present invention, it is possible to provide a heating device and a heating element that are durable even in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a plan view of a heating device according to an embodiment of the present invention; Fig. 1B is a cross-sectional view taken along line aa' in Fig. 1A; Fig. Figure 1C is an enlarged cross-sectional view of region R in Fig. 1B; Fig. 2 is a graph showing a relationship between temperatures of Mo, W, Ni-Cr alloy, Fe-Cr alloy, and Fe-Ni alloy and a change rate R1 of a mass at 700 °C relative to a mass at 25 °C; Fig. 3A is a result of durability evaluation for a heater 100 using a Ni-Cr alloy as an electrically heating portion; Fig. 3B is a result of durability evaluation for a heater using W as an electrically heating portion; Fig. 3C is a durability evaluation result for a heater using Mo as an electrically heating portion; Fig. 4 is a schematic view for explaining an arrangement pattern of a linear electrically heating portion; Fig. 5A is a plan view of a heating device according to another embodiment of the present invention; Fig. 5B is a cross-sectional view taken along line bb' in Fig. 5A; Fig. 6 is a cross-sectional view of a heating element according to an embodiment of the present invention; Fig. 7 is a plan view showing a state in which electrically heating portions of a plurality of heating devices according to an embodiment of the present invention are electrically connected in series to a power source; Fig. 8 is a plan view showing a state in which electrically heating portions of a plurality of heating devices according to an embodiment of the present invention are electrically connected in parallel to a power source; and Fig. 9 is a cross-sectional view of a heating element used to heat a reductant precursor to produce a reductant according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] A heating device according to the present invention, comprising: a first ceramic substrate; a glass portion provided on the first ceramic substrate; and an electrically heating portion embedded in the glass portion, wherein the glass portion has closed pores, and wherein the electrically heating portion comprises a metal, wherein a rate of change of a mass at 700°C relative to a mass at 25°C in the air atmosphere is 0.1% or less. In a heating device having such a structure, the glass portion functions as an intermediate region for reducing a difference in thermal expansion coefficient between the first ceramic substrate and the electrically heating portion. Furthermore, the elastic modulus can be reduced by the closed pores in the glass portion, thus reducing thermal stress in harsh environments.Furthermore, by using a metal whose mass change rate at 700 °C relative to the mass at 25 °C is 0.1 mass% or less, the metal is difficult to oxidize even at elevated temperatures. Therefore, the heater exhibits long-term durability even in harsh environments.

[0015] A heating element according to the present invention includes: a cylindrical member; the heaters, each of the heaters being arranged along an inner peripheral surface of at least a portion of the cylindrical member; and an insulating material disposed between the cylindrical member and each of the heaters; wherein the electric heating portions of the heaters can be electrically connected to a power source in series or parallel. The heating element includes the above heaters and therefore has long-lasting durability even in harsh environments.

[0016] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and those that add appropriate modifications, improvements, and the like to the following embodiments based on the knowledge of a person skilled in the art without departing from the spirit of the present invention also fall within the scope of the present invention. (1) Heating device

[0017] Fig. 1A is a plan view of a heating device according to an embodiment of the present invention and Fig. Figure 1B is a cross-sectional view of this heater along line a-a'. Fig. Figure 1C is an enlarged cross-sectional view of region R in Fig. 1B.

[0018] As in Fig. 1A to Fig. 1C, a heating device 100 includes: a first ceramic substrate 10; a glass portion 20 provided on the first ceramic substrate 10; and an electrically heating portion 30 embedded in the glass portion 20. It should be noted that in Fig. 1A, the dashed line indicates the position of the electrically heating portion 30 embedded in the glass portion 20. The glass portion 20 has a thermal expansion coefficient between the first ceramic substrate 10 and the electrically heating portion 30 and can therefore reduce a difference in thermal expansion coefficient between the first ceramic substrate 10 and the electrically heating portion 30, thereby reducing thermal stress in harsh environments. Since the first ceramic substrate 10 and the electrically heating portion 30 are not in direct contact with each other, the generation of cracks in the first ceramic substrate 10 can also be suppressed.

[0019] Each element is described below. <Erstes Keramiksubstrat 10>

[0020] The first ceramic substrate 10 may be a substrate containing an insulating ceramic such as alumina, silicon nitride, and cordierite as a main component, although not specifically limited thereto. Among these, from the perspective of stably ensuring long-term durability in harsh environments, it is preferable that the first ceramic substrate 10 be a cordierite substrate.

[0021] As used herein, the cordierite substrate refers to a substrate containing cordierite (2MgO 2Al 2 O 3 · 5SiO 2 ) as a main component.

[0022] As used herein, the term “main component” means a component in which a percentage of the component relative to the total component is more than 50 mass%, and preferably 90 mass% or more.

[0023] The cordierite substrate preferably consists of 90 mass% or more of a cordierite phase, 5 mass% or less of a crystalline phase containing mullite and / or spinel, and the remainder being a glass phase. Such a composition can allow properties such as thermal expansion coefficient and elastic modulus to be controlled within desired ranges.

[0024] As used herein, the mass % of each phase in the cordierite substrate is determined as follows. First, a plurality of samples are prepared by mixing cordierite, mullite, spinel, and glass at varying mass ratios, and a calibration curve of X-ray diffraction peak values ​​is established in advance. The peak values ​​are determined by X-ray diffraction of the cordierite substrate, and the mass ratio (mass %) of each phase in the cordierite substrate is determined based on the calibration curve.

[0025] The first ceramic substrate 10 preferably has an open porosity of 10% or less, and more preferably 5% or less, although not specifically limited thereto. When the heater 100 is used in an environment where a liquid such as a reducing agent precursor (e.g., urea water) adheres, controlling the open porosity to this range may make it difficult for the liquid to penetrate into the interior of the first ceramic substrate 10.

[0026] Here, the open porosity of the first ceramic substrate 10 can be measured using an existing test method (Archimedes method, JIS R 1634: 1998). The open porosity of the first ceramic substrate 10 can be controlled by reducing a particle size of a raw material powder or by adding a sintering aid or the like.

[0027] The first ceramic substrate 10 preferably has a thermal expansion coefficient (thermal expansion rate) of 1.5 × 10 -6 up to 2.0 × 10 -6 / K, although it is not specifically limited thereto. With the thermal expansion coefficient within such a range, the thermal stress in the harsh environment with large thermal fluctuations can be stably reduced, thus improving the long-term durability of the heater 100.

[0028] Here, the thermal expansion coefficient of the first ceramic substrate 10 can be measured according to JIS R 1618: 2002.

[0029] The first ceramic substrate 10 preferably has a Young's modulus of 160 GPa or less, although not specifically limited thereto. The Young's modulus within this range can stably reduce thermal stress in harsh environments with large thermal fluctuations, thus improving the long-term durability of the heater 100. Furthermore, in view of suppressing deformation and breakage of the heater 100 due to vibration, the Young's modulus of the first ceramic substrate 10 is preferably 100 GPa or more.

[0030] Here, the elastic modulus of the first ceramic substrate 10 can be calculated as follows. The flexural strength of the first ceramic substrate 10 is measured according to the four-point flexural strength test method defined in JIS R 1601: 2008, and a stress-strain curve is constructed from the measurement results. A slope of the thus obtained stress-strain curve is calculated, and the slope of the stress-strain curve is defined as the elastic modulus. <Glasabschnitt 20>

[0031] The glass portion 20 has closed pores 21. The presence of the closed pores 21 in the glass portion 20 reduces the elastic modulus of the glass portion 20, thereby reducing thermal stress in harsh environments with large thermal fluctuations.

[0032] As used herein, the "closed pores 21" refer to pores that exist independently in the glass portion 20 and are not connected to the outside. The glass portion 20 with the closed pores 21 can be formed by a method known in the art (such as controlling components and production conditions). Furthermore, open pores on the surface of the glass portion 20 with the open pores can be filled with a repair material or the like to form the closed pores. The repair material can be glass or another material.

[0033] The glass portion 20 preferably has a thermal expansion coefficient (thermal expansion rate) of less than 6.0 × 10 -6 / K and more preferably 2.0 × 10 -6 up to 5.0 × 10 -6 / K and even more preferably 2.0 × 10 -6 up to 4.0 × 10 -6 / K, although not specifically limited thereto. The thermal expansion coefficient of the glass portion 20 within the above range can reduce the difference between the thermal expansion coefficients of the glass portion 20 and the first ceramic substrate 10. As a result, thermal stress can be reduced in harsh environments with large thermal fluctuations, thus improving the long-term durability of the heater 100.

[0034] Here, the thermal expansion coefficient of the glass portion 20 can be measured in the same manner as the thermal expansion coefficient of the first ceramic substrate 10.

[0035] The glass portion 20 preferably has a Young's modulus of 5 to 50 GPa, and more preferably 5 to 40 GPa, although not specifically limited thereto. The Young's modulus in this range can stably reduce thermal stress in harsh environments with large thermal fluctuations, thus improving the long-term durability of the heater 100.

[0036] The elastic modulus of the glass portion 20 can be measured in the same manner as the elastic modulus of the first ceramic substrate 10.

[0037] The glass portion 20 may be formed using various known glasses.

[0038] The glass portion 20 generally contains boron and / or silicon. Examples of glasses used for the glass portion 20 include quartz glass, borosilicate glass, soda-lime glass, aluminoborosilicate glass, aluminosilicate glass, and crystallized glass. Among them, borosilicate glass is preferred due to its high heat resistance and low thermal expansion coefficient (low thermal expansion rate).

[0039] Furthermore, the glass portion 20 preferably has a glass transition temperature (Tg) of 600 to 1100 °C. The glass transition temperature in this range can increase the heat resistance, thereby improving the long-term durability of the heater 100.

[0040] Here, the glass transition temperature of glass section 20 can be measured according to JIS R3103-3: 2001. <Elektrisch heizender Abschnitt 30>

[0041] The electrically heating portion 30 is a conductor that generates heat through electrical conduction. The electrically heating portion 30 is made of a metal in which a change rate R1 of a mass at 700°C relative to a mass at 25°C in the air atmosphere is 0.1% or less. When the electrically heating portion 30 is made of such a metal, it is difficult to oxidize even under high-temperature conditions, thereby improving the long-term durability of the heating device 100.

[0042] The rate of change R1 of the mass at 700 °C relative to the mass at 25 °C can be calculated by using a thermogravimetric differential thermal analysis (TG-DTA) device to measure a mass change associated with a temperature change of the metal according to the following equation from the measured masses of the metal at 25 °C and 700 °C: Rate of change R1=(mass at 25°C−at 700°C) / mass at °C×100.

[0043] The metal with the above mass change rate R1 is not particularly limited, but an alloy containing one or more selected from Ni, Fe, and Cr can be used. Examples of the alloy include Ni-Cr alloys and Fe-Cr alloys. These can be used alone or in combination. The use of such an alloy makes it possible to stably suppress oxidation under high-temperature conditions.

[0044] In this regard, Fig. Figure 2 is a graph showing the relationship between temperature and the rate of change R1 of mass at 700 °C relative to the mass at 25 °C for Mo (molybdenum), W (tungsten), Ni-Cr alloy, Fe-Cr alloy and Fe-Ni alloy (Invar) as measured and calculated using a TG-DTA apparatus.

[0045] As in Fig. 2, only the Ni-Cr alloy and Fe-Cr alloy of the illustrated metals have a change rate R1 of the mass at 700 °C relative to the mass at 25 °C of 0.1% or less, indicating that they are oxidation-resistant even under high-temperature conditions.

[0046] Furthermore, the heaters 100 were actually manufactured using Ni-Cr alloy, W, and Mo as the electrically heating portions 30, and the durability of the heaters 100 was evaluated. In this evaluation, the cordierite substrate was used as the first ceramic substrate 10, and the borosilicate glass with closed pores 21 was used as the glass portion 20. The durability was evaluated by applying a voltage to each heater 100 and measuring the temperature of the heater over time. The evaluation results of the durability of the heater 100 using the Ni-Cr alloy as the electrically heating portion 30 are shown in Fig. 3A, the evaluation results of the durability of the heating device 100 using W as the electrically heating portion 30 are shown in Fig. 3B, and the evaluation results of the durability of the heater 100 using Mo as the electrically heating portion 30 are shown in Fig. 3C shown.

[0047] As in Fig. 3A, for the heater 100 using the Ni-Cr alloy as the electrically heating portion 30, substantially no change in the temperature of the heater 10 was observed even after 55 hours of voltage application.

[0048] In contrast, as in Fig. As shown in Figure 3B, for the heater 100 using W as the electrically heating portion 30, the temperature of the heater 100 decreased after about 620 seconds. Investigation into the cause confirmed that the electrically heating portion 30 had been disconnected.

[0049] Also, as in Fig. As shown in Figure 3C, for the heater 100 using Mo as the electrically heating portion 30, the temperature of the heater 100 decreased after about 14,500 seconds (about 4 hours). Investigation into the cause confirmed that the electrically heating portion 30 had been separated.

[0050] It is preferable that a change rate R2 of a volume resistivity at 300°C relative to a volume resistivity at 25°C of the electrically heating portion 30 is 10% or less. When the change rate R2 of the volume resistivity is within this range, it can be said that there is a slight change in the volume resistivity even when the temperature is changed, and the heating performance can be stably maintained even under high-temperature conditions.

[0051] The volume resistivity of the electrically heating portion 30 at each temperature can be measured by the four-terminal method.

[0052] The thermal expansion coefficient of the electrically heating portion 30 is not particularly limited, but may preferably be 2.0 × 10 -6 up to 15.0 × 10 -6 / K and more preferably 2.0 × 10 -6 up to 14.0 × 10 -6 / K. Since the thermal expansion of the electrically heating portion 30 can be absorbed by the closed pores 21 of the glass part 20, the thermal expansion coefficient of the electrically heating portion 30 can be relatively high.

[0053] The shape of the electrically heating portion 30 is not particularly limited and may take various forms, such as a linear shape, a plate shape, and a sheet shape. It should be noted that the Fig. 1A to Fig. 1C shows an example in which a linear electrically heating portion 30 is formed.

[0054] When the electrically heating portion 30 is linear, its arrangement pattern is not particularly limited and may be, for example, the arrangement pattern as shown by the dashed line in Fig. 1A. Since the outer periphery of the heater 100 cools easily, it is preferable to increase the density of the linear electrically heating portion 30 on the outer periphery of the heater 100 (ie, to narrow the distance between the linear electrically heating portions 30), as shown in Fig. 4, with respect to uniform heating of the heating device 100. It should be noted that Fig. 4 is a schematic view for explaining the arrangement pattern of the linear electrically heating portion 30 (a cross-sectional view of the electrically heating portion 30 parallel to the upper surface of the heater 100).

[0055] A second ceramic substrate may be further provided on the glass portion 20 in which the electrically heating portion 30 is embedded.

[0056] Here shows Fig. 5A is a plan view of a heating device further comprising a second ceramic substrate, and Fig. Figure 5B shows a cross-sectional view of the heater along line b-b'.

[0057] As in Fig. 5A and Fig. 5B, a heating device 200 includes: a first ceramic substrate 10; a glass portion 20 provided on the first ceramic substrate 10; an electrically heating portion 30 embedded in the glass portion 20; and a second ceramic substrate 40 provided on the glass portion 20. It should be noted that in Fig. 5A, the dashed line indicates the position of the electrically heating portion 30 embedded in the glass portion 20. In the heating device 200 having such a structure, the glass portion 20 functions as an intermediate region that reduces the difference in thermal expansion coefficient between the first and second ceramic substrates 10, 40 and the electrically heating portion 30. In addition, the elastic modulus can be reduced by the closed pores 21 of the glass portion 20, so that thermal stress in harsh environments is reduced. Furthermore, since the first and second ceramic substrates 10, 40 are prevented from coming into direct contact with the electrically heating portion 30, cracks in the first ceramic substrate 10 and the second ceramic substrate 40 can be suppressed. Therefore, the long-term durability of the heating device 200 is improved.

[0058] The second ceramic substrate 40 may be the same as the first ceramic substrate 10, so details thereof will not be described again.

[0059] The type of the second ceramic substrate 40 may be the same as or different from that of the first ceramic substrate 10, but it is preferable that they be of the same type. By having the first ceramic substrate 10 and the second ceramic substrate 40 of the same type, thermal stress can be stably reduced in harsh environments with large thermal fluctuations, thereby improving the long-term durability of the heater 200.

[0060] The heating device 100, 200 may further comprise terminals 50, each connected to the electrically heating portion 30 via a brazing material 60, as shown in Fig. 1A to Fig. 1B and Fig. 5A to Fig. 5B. Such a structure makes it easy to electrically connect the electrically heating portion 30 to an external power source (not shown).

[0061] The terminal 50 is made of a conductor suitable for current supply. The conductor used for the terminal 50 is not particularly limited, and metals or alloys 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.

[0062] It should be noted that the conductor used for the terminal 50 may be the same conductor as the electrically heating portion 30 or may be a conductor different from that of the electrically heating portion 30.

[0063] The conductor forming the terminal 50 preferably has a thermal expansion coefficient (thermal expansion rate) of more than 1.6 × 10 -6 / K and less than 6.0 × 10 -6 / K and more, preferably more than 3.0 × 10 -6 / K and less than 6.0 × 10 -6 / K or less, although it is not specifically limited thereto. The thermal expansion coefficient of the conductor within the above range constituting the terminal 50 may be the difference between the thermal expansion coefficients of the second ceramic substrate 40 and the conductor constituting the terminal 50 in the heating device 200 as shown in FIGS. Fig. 5A and Fig. 5B. As a result, the thermal stress in the environment with large thermal fluctuations can be reduced, thus improving the reliability of the heater 200. For example, Kovar has a thermal expansion coefficient of about 5.0 × 10 -6 / K on.

[0064] In the heating device 200, as in the Fig. 5A and Fig. 5B, each terminal 50 is preferably inserted into a through-hole provided in the second ceramic substrate 40. Such a structure makes it easy to electrically connect the electrically heating portion 30 to the external power source (not shown).

[0065] The brazing material 60 is a material for connecting the electrically heating portion 30 to the terminal 50. The brazing material 60 is not particularly limited, and a suitable material can be selected depending on the types of the electrically heating portion 30 and the terminals 50. For example, the brazing material 60 preferably contains Ag, Ti, and Cu. When the brazing material 60 contains such components, the electrically heating portion 30 and the terminals 50 can be properly connected without affecting them.

[0066] The heating device 100, 200 may further include a sealing portion 70 provided at an interface between the terminal 50 and the glass portion 20 or the second ceramic substrate 40, as shown in Fig. 1A to Fig. 1B and Fig. 5A to Fig. 5B. In particular, the heater 100 may be provided with the sealing portion 70 at the interface between the terminal 50 and the glass portion 20. Furthermore, the heater 200 may be provided with a sealing portion 70 at the interface between the terminal 50 and the second ceramic substrate 40. Such a structure can suppress the intrusion of liquid, air, or the like from the interface, so that the reliability of the heater 100, 200 can be improved.

[0067] A material for forming the sealing portion 70 is not particularly limited, and known sealing materials in the art can be used. Among them, the material forming the sealing portion 70 is preferably glass.

[0068] In addition, the sealing section 70 (glass) preferably contains SiO 2 and B 2 O 3 . Since the sealing portion 70 including such components has a lower thermal expansion coefficient, the cracks in the sealing portion 70 and members around it (the glass portion 20 and the second ceramic substrate 40) can be suppressed.

[0069] The glass forming the sealing portion 70 preferably has a thermal expansion coefficient (a thermal expansion rate) of more than 1.6 × 10 -6 / K and less than 6.0 × 10 -6 / K and more, preferably more than 2.0 × 10 -6 / K and less than 4.0 × 10 -6 / K, although it is not specifically limited thereto. The thermal expansion coefficient within the above-described range of the glass forming the sealing portion 70 reduces the difference between the thermal expansion coefficients of the glass portion 20 and the conductor forming the terminal 50 and the glass forming the sealing portion 70 for the heater 100, and reduces the difference between the thermal expansion coefficients of the second ceramic substrate 40 and the conductor forming the terminal 50 and the glass forming the sealing portion 70 for the heater 200. As a result, the thermal stress can be reduced in the harsh environments with large thermal fluctuations, so that the reliability of the heater 100, 200 can be improved.

[0070] The heaters 100, 200 having the structures described above can be used for various applications because they are durable even in harsh environments and can also suppress the generation of cracks in the ceramic substrates (the first ceramic substrate 10 and the second ceramic substrate 40).

[0071] For example, the heaters 100, 200 are useful for heating an exhaust gas in an exhaust mixer that mixes urea and the exhaust gas in a diesel engine urea-SCR system. In the urea-SCR system, the heaters 100, 200 are also useful for maintaining a high temperature of the inner wall surface of the cylindrical member (exhaust pipe) that forms the exhaust mixer and for preventing the urea from becoming a solid deposit that may accumulate when the urea collides with the inner wall surface. In the urea-SCR system, ammonia (NH 3), which is used as a NOx reducing agent, can be produced by injecting urea water into the exhaust gas heated by the heaters 100, 200.

[0072] Each of the heating devices 100, 200 is also useful as heating equipment for electric vehicles, fuel cell vehicles, and plug-in hybrid vehicles, and as a heating means for the synthetic fuel manufacturing process.

[0073] The heaters 100, 200 may be manufactured according to methods known in the art.

[0074] For example, the heating device 100 can be manufactured as follows: First, a molding material containing a ceramic raw material powder is molded and then sintered to produce the first ceramic substrate 10. Although the molding method is not particularly limited, extrusion molding, die casting, or the like may be used. Alternatively, the first ceramic substrate 10 may be manufactured by machining a sintered body having a predetermined shape.

[0075] The electrically heating portion 30 is then sandwiched between two glass sheets constituting the glass portion 20 and arranged on the first ceramic substrate 10 to form a stacked structure. At this time, the glass sheet is provided on the surface side with an opening for connecting the electrically heating portion 30 to each terminal 50 by means of the brazing material 60. Furthermore, when a glass sheet with open pores is used as the glass sheet, pore-closing treatment is performed to close the open pores on the surface with a repair material such as glass. When a glass sheet with closed pores is used, the pore-closing treatment is not required.

[0076] The stacked structure is then firmly bonded through a heating and pressing process. At this time, the glass sheets are firmly bonded to the glass section 20, and the electrically heating section 30 is embedded in the glass section 20. Although the heating and pressing conditions are not specifically limited, they can be appropriately adjusted according to the type of glass sheets to be used.

[0077] Each terminal 50 is then placed over the brazing material 60 onto the electrically heating portion 30 exposed in the opening of the surface-side glass panel, and then heated and connected. Although the heating conditions are not specifically limited, they can be appropriately adjusted according to the type of brazing material 60 to be used.

[0078] Finally, the sealing material is applied to the interface between each terminal 50 and the glass portion 20 on the surface of the glass portion 20 and then heated to form the sealing portion 70, thereby completing the heating device 100. Although the heating conditions are not specifically limited, they can be appropriately adjusted according to the type of sealing material to be used.

[0079] The heating device 200 can be manufactured as follows: First, molding materials each containing cordierite raw material powder are molded and then sintered to prepare the first ceramic substrate 10 and the second ceramic substrate 40.

[0080] The electrically heating portion 30 is then sandwiched between two glass sheets constituting the glass portion 20, and the glass sheet 20 is placed between the first ceramic substrate 10 and the second ceramic substrate 40 to form a stacked structure. At this time, through holes are provided in the second ceramic substrate 40 and in the glass sheet on the second ceramic substrate 40 side to connect the electrically heating portion 30 to each terminal 50 using the brazing material 60. Furthermore, when a glass sheet with open pores is used as the glass sheet, pore-closing treatment is performed to close the open pores on the surface with a repair material such as glass. When a glass sheet with closed pores is used, the pore-closing treatment is not required.

[0081] The stacked structure is then firmly bonded by heating while being pressed to improve the adhesion between the first ceramic substrate 10, the second ceramic substrate 40, and the glass sheets sandwiching the electrically heating portion 30.

[0082] Each terminal 50 is placed on the electrically heating portion 30 exposed in the opening of the second ceramic substrate 40 and the glass sheet on the second ceramic substrate 40 side via the brazing material 60, and then heated and connected.

[0083] Finally, the sealing material is applied to the interface between each terminal 50 and the second ceramic substrate 40 on the surface of the second ceramic substrate 40 and then heated to form the sealing portion 70, thereby completing the heating device 200. (2) Heating element

[0084] Fig. Figure 6 is a cross-sectional view of a heating element according to an embodiment of the present invention. It should be noted that Fig. 6 is a cross-sectional view of a cylindrical member 300 forming a heating element 1000 in a direction perpendicular to an axial direction.

[0085] As in Fig. As shown in Figure 6, the heating element 1000 includes: a cylindrical member 300; a plurality of heaters 100, 200 arranged along at least a portion of an inner peripheral surface of the cylindrical member 300; and an insulating material 400 disposed between the cylindrical member 300 and the heaters 100, 200. Such a structure can enable the interior of the cylindrical member 300 to be heated.

[0086] The cylindrical member 300 is not particularly limited, and it may have a uniform diameter in the axial direction, or it may have a reduced and / or increased diameter in the axial direction.

[0087] Although the material of the cylindrical member 300 is not particularly limited, it is preferably a metal from a manufacturability perspective. Examples of the metal that can be used herein include stainless steel, titanium alloys, copper alloys, aluminum alloys, and brass. Among them, stainless steel is preferred due to its high durability and reliability, as well as its low cost.

[0088] The cylindrical member 300 preferably has a thickness of 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more, although not specifically limited thereto. The thickness of the cylindrical member 300 of 0.1 mm or more can ensure durability and reliability. In addition, 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. The thickness of the cylindrical member 300 of 10 mm or less can achieve weight reduction.

[0089] The insulating material 400 is not particularly limited, and a fiber mat made of silicon nitride, alumina, or the like may be used.

[0090] A thickness of the insulating material 400 is not particularly limited as long as it can ensure insulation.

[0091] The plurality of heaters 100, 200 are arranged along at least a portion of the inner peripheral surface of the cylindrical member 300. Although one method for fixing the heaters 100, 200, for example, may be fixed to the inner peripheral surface of the cylindrical member 300 using fixing devices such as screws 500.

[0092] The plurality of heaters 100, 200 are configured such that the electric heating sections 30 can be electrically connected to a power source in series or parallel. Such a configuration can cause the plurality of heaters 100, 200 to generate heat by applying a voltage from the power source and allow the interior of the cylindrical member 300 to be heated.

[0093] Here shows Fig. 7 is a plan view showing a state in which the electric heating sections 30 of the plurality of heating devices 100, 200 are electrically connected in series to the power source. Also shown Fig. 8 is a plan view of a state in which the electric heating sections 30 of the plurality of heating devices 100, 200 are electrically connected in parallel to the power source. It should be noted that Fig. 7 and Fig. 8 shows the three heaters 100 as a plan view for easy understanding. The dashed lines indicate the positions of the embedded electric heating sections 30.

[0094] In Fig. 7, the electric heating sections 30 of the plurality of heating devices 100, 200 are electrically connected in series, one end of the electric heating sections 30 connected in series is electrically connected to the power source, and the other end is electrically connected to the ground (for example, the cylindrical member 300). In Fig. 8, the electric heating sections 30 of the plurality of heating devices 100, 200 are electrically connected in parallel, one end of each electric heating section 30 is electrically connected to the power source, and the other end is electrically connected to the ground (for example, the cylindrical member 300).

[0095] Although the applied voltage from the power source is not particularly limited, it is preferably 80 V or less. The voltage in this range does not require special insulation. Furthermore, in view of the heating efficiency of the heater, the applied voltage is preferably 12 V or more.

[0096] The heating element according to the embodiment of the present invention is suitable for use in the diesel engine urea SCR system. That is, the heating element according to the embodiment of the present invention can be used to maintain a higher temperature of the inner wall surface of the cylindrical member 300 constituting the exhaust mixer for mixing a reducing agent precursor (e.g., urea water) with the exhaust gas, and to heat the reducing agent precursor to generate a reducing agent (e.g., ammonia), while preventing the urea from becoming a solid intercalation deposit that may accumulate when the urea collides with the inner wall surface.

[0097] Fig. Figure 9 shows a cross-sectional view of a heating element used to heat the reducing agent precursor to produce the reducing agent. Note that Fig. 9 is a cross-sectional view of a cylindrical member 300 constituting a heating element 2000 in a direction perpendicular to the axial direction.

[0098] As in Fig.As shown in FIG. 9, the heating element 2000 is disposed on at least a portion of the cylindrical member 300 and further includes a nozzle 600 capable of injecting the reducing agent precursor onto the inner peripheral surface of the cylindrical member 300. Furthermore, the plurality of heaters 100, 200 are disposed on the inner peripheral surface of the cylindrical member 300, onto which the reducing agent precursor is injected from the nozzle 600. Furthermore, the cylindrical member 300 is an exhaust pipe of a diesel engine. Such a structure can enable the exhaust gas flowing through the cylindrical member 300 (exhaust pipe) to be heated by the plurality of heaters 100, 200, so that the reducing agent precursor can be injected into the heated exhaust gas to generate the reducing agent.Even if the reducing agent precursor injected from the nozzle 600 collides with the plurality of heaters 100, 200, the reducing agent precursor evaporates instantly, so that the accumulation of the intermediate product generated by decomposition of the reducing agent precursor can also be suppressed.

[0099] The heating element 2000 is preferably configured such that the electric heating sections 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 sections 30 of the plurality of heaters 100, 200 is electrically connected to the power source, and the other end is electrically connected to the ground (for example, the cylindrical member 300). In addition, a voltage applied by the power source is preferably 60 V or less. Such a configuration can enable the reducing agent precursor to be heated quickly and efficiently to generate the reducing agent, and enables the deposition of the intermediate product on the inner wall surface of the cylindrical member 300 to be suppressed. DESCRIPTION OF REFERENCE SYMBOLS 10 first ceramic substrate 20 glass sections 21 closed pore 30 electrically heated section 40 second ceramic substrate 50 connection 60 brazing material 70 Sealing section 100, 200 heater 300 cylindrical element 400 insulation material 500 screws 600 nozzle 1000, 2000 heating element QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2017-182890 A

[0008] JP 5748918 B

[0008] JP 2020-197208 A

[0008] Cited non-patent literature

[0000] JIS R 1634: 1998

[0026] JIS R 1601: 2008

[0030]

Claims

A heating device (100, 200) comprising: a first ceramic substrate (10); a glass portion (20) provided on the first ceramic substrate (10); and an electrically heating portion (30) embedded in the glass portion (20), wherein the glass portion (20) has closed pores (21), and wherein the electrically heating portion (30) comprises a metal, wherein a rate of change of a mass at 700°C relative to a mass at 25°C in the air atmosphere is 0.1% or less. The heating device (100, 200) according to claim 1, further comprising a second ceramic substrate (40) provided on the glass portion (20). Heating device (100, 200) according to claim 1 or 2, wherein the ceramic substrate is a cordierite substrate. Heating device (100, 200) according to one of claims 1 to 3, wherein the glass portion (20) has a thermal expansion coefficient of less than 6.0 × 10-6 / K. Heating device (100, 200) according to one of claims 1 to 4, wherein the glass portion (20) has a modulus of elasticity of 5 to 50 GPa. Heating device (100, 200) according to one of claims 1 to 5, wherein the glass portion (20) comprises boron and / or silicon and has a glass transition temperature of 600 to 1100 °C. A heating device (100, 200) according to any one of claims 1 to 6, wherein the electrically heating portion (30) has a rate of change of a volume resistivity at 300°C relative to a volume resistivity at 25°C of 10% or less. Heating device (100, 200) according to one of claims 1 to 7, wherein the electrically heating portion (30) comprises an alloy containing one or more selected from Ni, Fe and Cr. Heating device (100, 200) according to claim 8, wherein the alloy is a Ni-Cr alloy or a Fe-Cr alloy. Heating device (100, 200) according to one of claims 1 to 9, further comprising a terminal (50) connected to the electrically heating section (30). Heating device (100, 200) according to claim 10, wherein the terminal (50) is connected to the electrically heating portion (30) via a brazing material (60). Heating device (100, 200) according to one of claims 1 to 11, wherein the heating device (100, 200) is used for heating an exhaust gas. A heating element (1000, 2000) comprising: a cylindrical member (300); the heaters (100, 200) according to any one of claims 1 to 12, wherein each of the heaters (100, 200) is arranged along an inner peripheral surface of at least a portion of the cylindrical member (300); and an insulating material (400) arranged between the cylindrical member (300) and each of the heaters (100, 200); wherein the electrically heating portions (30) of the heaters (100, 200) can be electrically connected to a power source in series or in parallel. A heating element (1000, 2000) according to claim 13, which is used for heating a reducing agent precursor to produce a reducing agent, wherein the heating element (1000, 2000) further comprises a nozzle (600) capable of injecting the reducing agent precursor onto an inner peripheral surface of the cylindrical member (300), the nozzle (600) being arranged on at least a part of the cylindrical member (300), each of the heating devices (100, 200) being arranged on the inner peripheral surface of the cylindrical member (300) onto which the reducing agent precursor is injected through the nozzle (600), and wherein the cylindrical member (300) is an exhaust pipe for a diesel engine. A heating element (1000, 2000) according to claim 14, wherein each of the electrically heating portions (30) of the heaters (100, 200) has one end electrically connected to the power source and another end electrically connected to the cylindrical member (300), and wherein a voltage applied by the power source is 80 V or less.

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