Patent Application
20250168932
The present invention claims the benefit of priority to Japanese Patent Application No 2023-196927 filed on Nov. 20, 2023 with the Japanese Patent Office, the entire contents of which are incorporated herein by reference in its entirety.
The present invention relates to a heater and a heating member.
There is an increasing demand for reduction of harmful components (HC, NOx, CO) in exhaust gases from motor vehicles. In particular, purification of NOx emitted from diesel engines is an important issue. A technology called a urea SCR system is generally known in the art as a measure for removing NOx. In the urea SCR system, thermal decomposition and hydrolysis of urea produce NH3, which is a NOx reducing agent. Efficient heating of urea is required for efficient thermal decomposition and hydrolysis of urea. However, with improvement of an engine efficiency, a temperature of the exhaust gas has been decreased, 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 the urea is injected into the exhaust gas, so that NH3 is not sufficiently generated. Further, 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 NH3, so that the urea will be converted to an intermediate solid deposit, which is accumulated. As a result, it will become an obstacle to the flow of the exhaust gas, or inhibit mixing of the generated NH3 and the exhaust gas due to a change in the flow of the exhaust gas. Therefore, heaters have been developed that can efficiently heat the exhaust gas and maintain the inner wall surface of the exhaust pipe at a high temperature.
Further, in battery electric vehicles (BEVs) and fuel cell vehicles (FCVs) which do not have any heat source from the internal combustion engine, and plug-in hybrid vehicles (PHVs: Plug-in Hybrid Vehicle, PHEVs (Plug-in Hybrid Electrical Vehicles)) which frequently stop the internal combustion engine, an increase in a heating efficiency is an important issue because a heating load affects the traveling distance. Therefore, heaters are being developed that can efficiently heat only a specific space in a short period of time, instead of heating the entire vehicle interior.
Furthermore, to achieve carbon neutrality, the development of synthetic fuels, which are obtained by synthesizing hydrogen produced by the electrolysis of water and CO2 emitted from power plants and factories, is being progressed, but heating is required for a production process of the synthetic fuel. If the production process is carried out in a place where it is possible to supply factory waste heat or like, the heat source can be easily ensured, but if it is carried out in a place where there is no heat source, it must be heated using electric power. The electric power is preferably produced from renewable energy that does not emit CO2 during the production process, so that the heater is also required to have an improved heating efficiency.
A heater in which conductors are embedded in substrates with a low heat capacity or the conductor is arranged between the substrates is one of effective heating means for various applications as described above.
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 for energizing 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 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.
Patent Literature 2 proposes a heater, comprising: an insulating substrate made of alumina ceramics, silicon nitride ceramics, or the like; and a resistor embedded in the insulating substrate, wherein the resistor contains first conductive particles mainly based on tungsten and second conductive particles mainly based on molybdenum.
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, which are provided inside the outer cylinder; and an electrically heating portion embedded in at least a part of the outer cylinder and/or the fins.
Heaters used for the applications as described above are required to be able to heat quickly and efficiently, and to have long-term durability in harsh environments (specifically, environments requiring corrosion resistance, heat resistance, impact resistance, insulation, etc.).
However, for the heaters described in the prior arts described above, it is difficult to ensure long-term durability in harsh environments depending on the types of substrates and conductors. For example, since an alumina substrate has a high coefficient of thermal expansion, it is difficult to ensure long-term durability in environments with large temperature changes because thermal stress increases. Further, although a cordierite substrate has a low coefficient of thermal expansion, when a conductor having a high coefficient of thermal expansion 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 coefficient of thermal expansion in environments with large temperature changes, so that it is difficult to ensure long-term durability. Furthermore, conductors such as molybdenum and tungsten are 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 that disconnection eventually occurs, so that it is difficult to ensure long-term durability.
The present invention is made to solve the above problems. An object of the present invention is to provide a heater and a heating member, which have long-term durability even in harsh environments.
As a result of intensive studies, the present inventors have found that the above 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 heater, comprising: a first ceramic substrate; a glass portion provided on the first ceramic substrate; and an electrically heating portion embedded in the glass portion,
The heater according to [1], further comprising a second ceramic substrate provided on the glass portion.
[3]
The heater according to [1] or [2], wherein the ceramic substrate is a cordierite substrate.
[4]
The heater according to any one of [1] to [3], wherein the glass portion has a coefficient of thermal expansion of less than 6.0×10−6/K.
[5]
The heater according to any one of [1] to [4], wherein the glass portion has a Young's modulus of 5 to 50 GPa.
[6]
The heater according to any 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 heater according to any one of [1] to [6], wherein the electrically heating portion has a rate of change of a volume resistivity at 300° C. relative to a volume resistivity at 25° C. of 10% or less.
[8]
The heater 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]
The heater according to [8], wherein the alloy is a Ni—Cr alloy or an Fe—Cr alloy.
[10]
The heater according to any one of [1] to [9], further comprising a terminal connected to the electrically heating portion.
[11]
The heater according to [10], wherein the terminal is connected to the electrically heating portion via a brazing material.
[12]
The heater according to any one of [1] to [11], wherein the heater is used for heating an exhaust gas.
[13]
A heating member, comprising:
The heating member according to used for heating a reducing agent precursor to generate a reducing agent,
The heating member according to [14],
A heater according to the present invention includes: 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 includes a metal wherein a mass change rate at 700° C. relative to a mass at 25° C. in the air atmosphere is 0.1% or less. In a heater having such a structure, the glass portion functions as an intermediate region for reducing a difference in coefficient of thermal expansion between the first ceramic substrate and the electrically heating portion. Also, the Young's modulus can be reduced by the closed pores in the glass portion, so that thermal stress in harsh environments is reduced. Furthermore, by using a metal in which a change of rate of a mass at 700° C. relative to the mass at 25° C. is 0.1% by mass or less, the metal is difficult to be oxidized even at elevated temperature. Therefore, the heater has long-term durability even in harsh environments.
A heating member according to the present invention includes: a cylindrical member; the heaters, each of the heaters being disposed 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 heaters; wherein the electrically heating portions of the heaters can be electrically connected to a power source in series or in parallel. The heating member includes the above heaters, and therefore has long-term durability even in harsh environments.
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. It is to understand that the present invention is not limited to the following embodiments, and those which have appropriately added changes, improvements and the like to the following embodiments based on knowledge of a person skilled in the art without departing from the spirit of the present invention fall within the scope of the present invention.
As shown in
Hereinafter, each member will be described.
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 particularly limited thereto. Among these, from the viewpoint of stably ensuring long-term durability in harsh environments, it is preferable that the first ceramic substrate 10 is a cordierite substrate.
As used herein, the cordierite substrate refers to a substrate containing cordierite (2MgO·2Al2O3·5SiO2) as a main component.
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% by mass, and preferably 90% by mass or more.
The cordierite substrate is preferably comprised of 90% by mass or more of a cordierite phase, 5% by mass or less of a crystalline phase containing mullite and/or spinel, the balance being a glass phase. Such a composition can allow properties such as a coefficient of thermal expansion and Young's modulus to be controlled within desired ranges.
As used herein, the % by 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 variable mass ratios, and a calibration curve of X-ray diffraction peak values is created in advance. The peak values are determined by X-ray diffraction of the cordierite substrate, and the mass ratio (% by mass) of each phase in the cordierite substrate is determined based on the calibration curve.
The first ceramic substrate 10 preferably has an open porosity of 10% or less, and more preferably 5% or less, although not particularly 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, the control of the open porosity to that range can make it difficult for the liquid to penetrate to the interior of the first ceramic substrate 10.
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.
The first ceramic substrate 10 preferably has a coefficient of thermal expansion (rate of thermal expansion) of 1.5×10−6 to 2.0×10−6/K, although not particularly limited thereto. With the coefficient of thermal expansion within such a range, thermal stress can be stably reduced in the harsh environment with large thermal fluctuations, so that the long-term durability of the heater 100 is improved.
Here, the coefficient of thermal expansion of the first ceramic substrate 10 can be measured according to JIS R 1618:2002.
The first ceramic substrate 10 preferably has a Young's modulus of 160 GPa or less, although not particularly limited thereto. The Young's modulus within this range can stably reduce the thermal stress in the harsh environments with large thermal fluctuations, so that the long-term durability of the heater 100 is improved. Moreover, the Young's modulus of the first ceramic substrate 10 is preferably 100 GPa or more from the viewpoint of suppressing deformation and breakage of the heater 100 due to vibration.
Here, the Young's modulus of the first ceramic substrate 10 can be calculated as follows. The bending strength of the first ceramic substrate 10 is measured according to the four-point bending strength test method defined in JIS R 1601:2008, and a “stress-strain curve” is created from the measurement results. A slope of the “stress-strain curve” thus obtained is calculated, and the slope of the “stress-strain curve” is defined as Young's modulus.
The glass portion 20 has closed pores 21. The presence of the closed pores 21 in the glass portion 20 reduces the Young's modulus of the glass portion 20, thereby reducing thermal stress in harsh environments with large thermal fluctuations.
As used herein, the “closed pores 21” refer to pores that are independently present in the glass portion 20 and are not connected to the outside. The glass portion 20 having the closed pores 21 can be formed by a method known in the art (such as control of components and production conditions). Also, open pores on the surface of the glass portion 20 having the open pores may be filled with a repair material or the like to make the closed pores. The repair material may be glass or another material.
The glass portion 20 preferably has a coefficient of thermal expansion (rate of thermal expansion) of less than 6.0×10−6/K, and more preferably 2.0×10−6 to 5.0×10−6/K, and even more preferably 2.0×10−6 to 4.0×10−6/K, although not particularly limited thereto. The coefficient of thermal expansion of the glass portion 20 within the above range can reduce the difference between the coefficients of thermal expansion of the glass portion 20 and the first ceramic substrate 10. As a result, the thermal stress can be reduced in the harsh environments with large thermal fluctuations, so that the long-term durability of the heater 100 is improved.
Here, the coefficient of thermal expansion of the glass portion 20 can be measured in the same manner as the coefficient of thermal expansion of the first ceramic substrate 10.
The glass portion 20 preferably has a Young's modulus of 5 to 50 GPa, and more preferably 5 to 40 GPa, although not particularly limited thereto. The Young's modulus in this range can stably reduce thermal stress in harsh environments with large thermal fluctuations, so that the long-term durability of the heater 100 can be improved.
The Young's modulus of the glass portion 20 can be measured in the same manner as the Young's modulus of the first ceramic substrate 10.
The glass portion 20 can be formed using various known glasses.
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 these, borosilicate glass is preferred because of its high heat resistance and low coefficient of thermal expansion (low rate of thermal expansion).
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.
Here, the glass transition temperature of the glass portion 20 can be measured in accordance with JIS R3103-3:2001.
The electrically heating portion 30 is a conductor that generates heat by electrical conduction. The electrically heating portion 30 is made of a metal in which a rate of change R1 of a mass at 700° C. relative to a mass at 25° C. in the air atmosphere is 0.1% or less. By making the electrically heating portion 30 from such a metal, it will be difficult to be oxidized even under high temperature conditions, thereby improving the long-term durability of the heater 100.
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, in accordance with the following equation from the measured masses of the metal at 25° C. and 700° C.:
The metal having the above rate of change R1 of the mass 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 allows oxidation under high temperature conditions to be stably suppressed.
For reference,
As shown in
Further, the heaters 100 were actually produced using Ni—Cr alloy, W, and Mo as the electric 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 having the 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
As shown in
In contrast, as shown in
Also, as shown in
It is preferable that a rate of change 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. If the rate of change R2 of the volume resistivity is in this range, it can be said that there is a little change of the volume resistivity even if the temperature is changed, and heating performance can be stably maintained even under high temperature conditions.
The volume resistivity of the electrically heating portion 30 at each temperature can be measured by the four-terminal method.
The coefficient of thermal expansion of the electrically heating portion 30 is not particularly limited, but it may preferably be 2.0×10−6 to 15.0×10−6/K, and more preferably 2.0×10−6 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 coefficient of thermal expansion of the electrically heating portion 30 may be relatively high.
The shape of the electrically heating portion 30 is not particularly limited, and it may be various shapes such as a linear shape, a plate shape, and a sheet shape. It should be noted that
When the electrically heating portion 30 is linear, its arrangement pattern is not particularly limited, and it may be, for example, the arrangement pattern as shown by the dotted line in
A second ceramic substrate can be further provided on the glass portion 20 in which the electrically heating portion 30 is embedded.
Here,
As shown in
The second ceramic substrate 40 can be the same as the first ceramic substrate 10, and so details will be omitted.
The type of the second ceramic substrate 40 may be the same as or different from the first ceramic substrate 10, but it is preferable that they are the same as each other. By making the first ceramic substrate 10 and the second ceramic substrate 40 the same type, the thermal stress in harsh environments with large thermal fluctuations can be stably reduced, thereby improving the long-term durability of the heater 200.
The heater 100, 200 may further include terminals 50 each connected to the electrically heating portion 30 via a brazing material 60, as shown in
The terminal 50 is comprised of a conductor capable of energization. The conductor used for the terminal 50 is not particularly limited, and metals or alloys known in the art may be used. Among them, the conductor used for the terminal 50 preferably contains Fe, Ni and Co. As such a material, Kovar can be used, for example.
It should be noted that the conductor used for the terminal 50 may be comprised of the same conductor as the electrically heating portion 30, or may be comprised of a conductor different from that of the electrically heating portion 30.
The conductor making up the terminal 50 preferably has a coefficient of thermal expansion (rate of thermal expansion) 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 not particularly limited thereto. The coefficient of thermal expansion of the conductor making up the terminal 50 within the above range can reduce the difference between the coefficients of thermal expansion of the second ceramic substrate 40 and the conductor making up the terminal 50 in the heater 200 as shown in
In heater 200 as shown in
The brazing material 60 is a material for joining the electrically heating portion 30 to the terminal 50. The brazing material 60 is not particularly limited, and an appropriate material may be selected depending on types of the electrically heating portion 30 and the terminals 50. For example, the brazing material 60 preferably contains Ag, Ti and Cu. If the brazing material 60 contains such components, the electrically heating portion 30 and the terminals 50 can be appropriately joined without affecting them.
The heater 100, 200 may further include a sealing portion 70 provided at a boundary surface between the terminal 50 and the glass portion 20 or the second ceramic substrate 40, as shown in
A material for forming the sealing portion 70 is not particularly limited, and known sealing materials in the art may be used. Among them, the material forming the sealing portion 70 is preferably glass.
Also, the sealing portion 70 (glass) preferably contains SiO2 and B2O3. Since the sealing portion 70 containing such components has a lower coefficient of thermal expansion, the cracks in the sealing portion 70 and members around it (the glass portion 20 and the second ceramic substrate 40) can be suppressed.
The glass making up the sealing portion 70 preferably has a coefficient of thermal expansion (a rate of thermal expansion) 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 not particularly limited thereto. The coefficient of thermal expansion of the glass making up the sealing portion 70 within the range as described above reduces the difference between the coefficients of the thermal expansion of the glass portion 20, and the conductor making up the terminal 50 and the glass making up the sealing portion 70 for the heater 100, and reduces the difference between the coefficients of thermal expansion of the second ceramic substrate 40, and the conductor making up the terminal 50 and the glass making up the sealing portion 70 for the heater 200. As a result, the thermal stress in the harsh environments with large thermal fluctuations can be reduced, so that the reliability of the heater 100, 200 can be improved.
The heaters 100, 200 having the structures as described above can be used for various applications, because they have long-term durability 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).
For example, the heaters 100, 200 are useful for heating an exhaust gas in an exhaust gas 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 gas mixer, and preventing the urea from becoming an intermediate solid deposit to be accumulated when the urea collides with the inner wall surface. In the urea SCR system, ammonia (NH3) that will be used as a NOx reducing agent can be produced by injecting urea water into the exhaust gas heated by the heaters 100, 200.
Each of the heaters 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 production process of the synthetic fuel.
The heaters 100, 200 can be produced according to methods known in the art.
For example, the heater 100 can be produced as follows:
First, a forming material containing ceramic raw material powder is formed and then sintered to produce the first ceramic substrate 10. Although the forming method is not particularly limited, extrusion molding, mold cast molding, or the like may be used. Alternatively, the first ceramic substrate 10 may be produced by machining a sintered body having a predetermined shape.
The electrically heating portion 30 is then sandwiched between two glass sheets that will form the glass portion 20, and arranged on the first ceramic substrate 10 to form a stacked structure. At this time, the glass sheet on the surface side is provided with an opening for connecting the electrically heating portion 30 to each terminal 50 with the brazing material 60. Also, when a glass sheet having open pores is used as the glass sheet, a pore-closing treatment is performed to close the open pores on the surface with a repair material such as glass. If a glass sheet having closed pores is used, the pore-closing treatment is not required.
The stacked structure is then integrated by a heating and pressing process. At this time, the glass sheets are integrated to form the glass portion 20, and the electrically heating portion 30 is embedded in the glass portion 20. Although the heating and pressing conditions are not particularly limited, they may be appropriately set according to the type of the glass sheets to be used.
Each terminal 50 is then placed on the electrically heating portion 30 exposed in the opening of the glass sheet on the surface side via the brazing material 60, and then heated and joined. Although the heating conditions are not particularly limited, they may be appropriately set according to the type of the brazing material 60 to be used.
Finally, the sealing material is applied to the boundary 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 heater 100. Although the heating conditions are not particularly limited, they may be appropriately set according to the type of the sealing material to be used.
The heater 200 can be produced as follows:
First, forming materials each containing cordierite raw material powder are formed and then sintered to produce the first ceramic substrate 10 and the second ceramic substrate 40.
The electrically heating portion 30 is then sandwiched between two glass sheets that will form the glass portion 20, and this is placed between the first ceramic substrate 10 and the second ceramic substrate 40 to form a stacked structure. At this time, the second ceramic substrate 40 and the glass sheet on the second ceramic substrate 40 side are provided with an opening for connecting the electrically heating portion 30 to each terminal 50 with the brazing material 60. Also, when a glass sheet having open pores is used as the glass sheet, a pore-closing treatment is performed to close the open pores on the surface with a repair material such as glass. If a glass sheet having closed pores is used, the pore-closing treatment is not required.
The stacked structure is then integrated by heating the stacked structure while pressing it in order to improve the adhesiveness among the first ceramic substrate 10, the second ceramic substrate 40, and the glass sheets sandwiching the electrically heating portion 30.
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 joined.
Finally, the sealing material is applied to the boundary 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 heater 200.
As shown in
The cylindrical member 300 is not particularly limited, and it may have a uniform diameter in the axial direction, or may have a decreased and/or increased diameter in the axial direction.
Although the material of the cylindrical member 300 is not particularly limited, it is preferably a metal from the viewpoint of manufacturability. Examples of the metal that can be used herein include stainless steel, titanium alloys, copper alloys, aluminum alloys, and brass. Among them, the stainless steel is preferable because of its high durability and reliability and low cost.
The cylindrical member 300 preferably has a thickness of 0.1 mm or more, and more preferably 0.3 mm or more, and even more preferably 0.5 mm or more, although not particularly limited thereto. The thickness of the cylindrical member 300 of 0.1 mm or more can ensure durability and reliability. Also, the thickness of the cylindrical member 300 is preferably 10 mm or less, and 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.
The insulating material 400 is not particularly limited, and a fiber mat made of silicon nitride, alumina, or the like may be used.
A thickness of the insulating material 400 is not particularly limited as long as it can ensure insulation.
The plurality of the heaters 100, 200 are arranged along at least a part of the inner peripheral surface of cylindrical member 300. Although a method for fixing the heaters 100, 200, for example, they may be fixed to the inner peripheral surface of the cylindrical member 300 using fixing jigs such as bolts 500.
The plurality of heaters 100, 200 are configured such that the electrically heating portions 30 can be electrically connected to a power source in series or in parallel. Such a configuration can cause the plurality of the 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.
Here,
In
Although the voltage applied from the power source is not particularly limited, it is preferably 80 V or less. The voltage in this range do not require special insulation. Further, the applied voltage is preferably 12 V or more, in view of the heating efficiency of the heater 100, 200.
The heating member according to the embodiment of the present invention is suitable for use in the diesel engine urea SCR system. That is, the heating member 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 that forms the exhaust gas mixer for mixing a reducing agent precursor (e.g., urea water) with the exhaust gas, and heat the reducing agent precursor to generate a reducing agent (e.g., ammonia) while preventing the urea from becoming an intermediate solid deposit to be accumulated when the urea collides with the inner wall surface.
As shown in
The heating member 2000 is preferably configured such that electrically heating portions 30 of the plurality of the 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 the heaters 100, 200 are electrically connected to the power source and the other end is electrically connected to the ground (for example, the cylindrical member 300). Also, a voltage applied from the power source is preferably 60 V or less. Such a configuration can allow the reducing agent precursor to be rapidly and efficiently heated to generate the reducing agent, and allow the deposition of the intermediate onto the inner wall surface of the cylindrical member 300 to be suppressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-196927 | Nov 2023 | JP | national |
