Joined body, corrosive gas treatment device, and tractor

Abstract

This joined body comprises an insulation member that includes a ceramic, and a retaining member that surrounds the insulation member and has an enlarged-diameter part in which the inside diameter is enlarged. The joined body also has a contact part at which the outer-side surface of the insulation member and the inner-side surface of the retaining member contact one another, and a first brazing part that joins the outer-side surface of the insulation member and the inner-side surface of the retaining member. The contact part and the first brazing part are positioned sandwiching the enlarged-diameter part.

Description

Joint, corrosive gas treatment device and tractor

[0001] The present disclosure relates to a joint body applied to an airtight terminal or the like, a corrosive gas treatment device, and a tractor.

[0002] Conventionally, agricultural machinery such as tractors, construction machinery, and ships are equipped with diesel engines equipped with diesel particulate filters (hereinafter, the diesel particulate filters will be simply referred to as filters) that capture particulate matter (PM) in exhaust gases. Patent Document 1 proposes a purification device that provides a heater in the exhaust system upstream of the filter to efficiently regenerate the filter, and that energizes the heater to raise the exhaust temperature during filter regeneration.

[0003] When applying current to a terminal portion of a heater or the like, an airtight terminal such as that proposed in Patent Document 2 has been considered. This airtight terminal comprises a metal tube joined to a through hole of an airtight container, a cylindrical ceramic insulator inserted into the through hole of the metal tube, a current-carrying conductor inserted into the through hole of the ceramic insulator and provided with terminal portions on both ends, a cap that airtightly joins the metal tube and the ceramic insulator on the side of the airtight container that comes into contact with the outside air, and another cap that airtightly joins the ceramic insulator and the current-carrying conductor. In the airtight terminal, the current-carrying conductor is supported inside the airtight container by an insulator fixed to the inner surface of the airtight container or the metal tube.

[0004] As a variant, Patent Document 2 also proposes an airtight terminal in which a thermosetting insulating material is injected into the gap between the current-carrying conductor and the ceramic insulator and the gap between the ceramic insulator and the metal tube to fix the gap between the current-carrying conductor and the ceramic insulator, and also the gap between the ceramic insulator and the metal tube.

[0005] JP 2013-11256 A JP 07-153512 A

[0006] The joined body of the present disclosure includes an insulating member containing ceramics, a holding member surrounding the insulating member and having an expanded diameter portion whose inner diameter expands, a contact portion where an outer surface of the insulating member and an inner surface of the holding member contact each other, and a first brazing portion joining the outer surface of the insulating member and the inner surface of the holding member. The contact portion and the first brazing portion are positioned on either side of the expanded diameter portion.

[0007] Another joined body of the present disclosure includes an insulating member containing ceramics, a retaining member surrounding the insulating member and having an expanded diameter portion whose inner diameter expands, and a sleeve disposed between the insulating member and the retaining member, and has a first brazing portion joining the insulating member and the sleeve, and a second brazing portion joining the retaining member and the sleeve.

[0008] A corrosive gas treatment device of the present disclosure includes the above-described joined body. A tractor of the present disclosure is equipped with the above-described corrosive gas treatment device.

[0009] Fig. 1 is a schematic cross-sectional view showing a bonded body according to one embodiment of the present disclosure; Fig. 2 is a schematic cross-sectional view showing a bonded body according to another embodiment of the present disclosure; Fig. 3 is a schematic cross-sectional view showing yet another example of a bonded body according to an embodiment of the present disclosure; Fig. 4 is a schematic cross-sectional view showing yet another example of a bonded body according to an embodiment of the present disclosure;

[0010] The airtight terminal proposed in Patent Document 2 requires a large space inside the airtight container to accommodate the insulator that supports the airtight terminal, and such an airtight terminal cannot be used if a large space cannot be secured. Also, if the airtight insulated terminal proposed as a modified example is used in a space exposed to corrosive gas, the thermosetting insulator is easily eroded by the corrosive gas.

[0011] Therefore, there is a demand for a joined body that can be used as an airtight terminal in an environment where a corrosive gas flows and that can maintain high joining strength and high airtightness even when the internal space is small.

[0012] A bonded structure according to one embodiment of the present disclosure will be described below with reference to FIG. 1. However, the figures referred to below show simplified embodiments of the present disclosure for the sake of convenience. Therefore, the bonded structure disclosed below may include any components not shown in the figures referred to. Furthermore, the dimensions of the components in the figures do not faithfully represent the actual dimensions of the components and the dimensional ratios of each component. FIG. 1 is a schematic cross-sectional view showing a bonded structure 1 according to this embodiment.

[0013] 1 is used as an airtight terminal and includes an insulating member 2 containing a cylindrical ceramic and having a through hole 21 in the axial direction, and a holding member 3 that holds the insulating member 2. At least a portion of a conductive member that passes current is located within the through hole 21 of the insulating member 2. The conductive member is used to introduce current to a thermal control element such as a heater, for example.

[0014] This thermal control element is installed in the exhaust system upstream of a filter installed in an engine mounted on a vehicle such as a tractor or other agricultural machinery, construction machinery, a ship, or an automobile. The thermal control element raises its temperature by passing current through a conductive member, thereby efficiently regenerating the filter. Exhaust gas is high-pressure and contains corrosive gases such as nitrogen oxides and sulfur oxides. Therefore, high airtightness is required for the hermetic terminals used in corrosive gas treatment devices (purification devices) used in such corrosive gases.

[0015] In Figure 1, arrow P indicates pressure due to corrosive gases, etc. There is a high-pressure side A1 on which a thermal control element such as a heater is installed, and a low-pressure side A2 on the opposite side, via the bonded body 1. The space on the low-pressure side A2 has a lower pressure than the space on the high-pressure side A1, and is at or near atmospheric pressure.

[0016] The insulating member 2 is made of, for example, alumina (Al ２ O ３ The insulating member 2 is made of an insulating material containing Al-based ceramics and has the function of maintaining electrical insulation and holding the conductive member located in the through hole 21. ２ O ３ When the porous ceramics are included, alumina and silicon oxide (SiO ２ ), magnesium hydroxide (Mg(OH) ２ ) or calcium carbonate (CaCO ３A raw material powder containing the above-mentioned components and water as a solvent is mixed and pulverized in, for example, a mill to obtain a slurry. Examples of mills include a vibration mill, a bead mill, a sand mill, an agitator mill, and a ball mill. A binder such as polyvinyl alcohol is added to and mixed with this slurry, and then the mixture is dried using a spray dryer to obtain granules. This is then filled into a press mold of a predetermined shape and pressed at a predetermined pressure to obtain a molded body, which is then fired at a temperature of 1550°C to 1750°C to obtain the insulating member 2.

[0017] The holding member 3 that holds the insulating member 2 surrounds the insulating member 2 and has an expanded diameter portion 31 with an expanding inner diameter. A contact portion 32 and a first brazing portion 33 are located on either side of the expanded diameter portion 31. The contact portion 32 contacts the outer surface of the high-pressure side A1 of the insulating member 2 with the inner surface of the holding member 3. The first brazing portion 33 joins the outer surface of the low-pressure side A2 of the insulating member 2 with the inner surface of the holding member 3. The first brazing portion 33 may be the entire inner surface of the holding member 3 that contacts the outer surface of the low-pressure side A2 of the insulating member 2, or only a portion thereof.

[0018] The holding member 3 may include Ti, a Ti alloy, Mo, Cu-Ni, Cu, an Fe-Co alloy, an Fe-Co-C alloy, an Fe-Ni alloy, an Fe-Ni-Co alloy, a ferritic stainless steel such as SUS430, SUS434, or SUS405, a martensitic stainless steel such as SUS403, US410, or SUS431, an austenitic stainless steel such as SUS201, SUS301, or SUS305, or a nickel-based superalloy. The holding member 3 is obtained by forming these metals into a predetermined shape by pressure forming or the like and then grinding them as necessary. The surface of the holding member 3 to which the first brazing portion 33 is brazed may be pre-plated with Ni to a thickness of approximately 1 μm to 3 μm to improve wettability with the brazing filler metal.

[0019] At the contact portion 32, any gap that occurs between the inner surface of the holding member 3 and the outer surface of the insulating member 2 is due only to the surface properties of each. Therefore, the flow rate of corrosive gas leaking through this gap is reduced. Specifically, the inner surface of the holding member 3 at the contact portion 32 may have an average value of arithmetic mean roughness (Ra) in a roughness curve of 1 μm or more, or 2 μm or more and 6.5 μm or less, and preferably 6.3 μm or less.

[0020] The inner surface may have an average value of a cut level difference (Rδc) (hereinafter simply referred to as cut level difference (Rδc)) representing the difference between the cut level at a load length ratio of 25% and the cut level at a load length ratio of 75% in a roughness curve, of 11 μm or less, or may be 10 μm or less.

[0021] The outer surface of the insulating member 2 at the contact portion 32 may have an average value of arithmetic mean roughness (Ra) in a roughness curve of 0.6 μm or more, or 0.8 μm or more and 2 μm or less, preferably 1.6 μm or less. The outer surface may have an average value of cut level difference (Rδc) of 3.1 μm or less, or 2.4 μm or less.

[0022] In particular, the difference between the average value of the arithmetic mean roughness (Ra) of the inner surface and the average value of the arithmetic mean roughness (Ra) of the outer surface is preferably 4.7 μm or less, and the difference between the average value of the cut level difference (Rδc) of the inner surface and the average value of the cut level difference (Rδc) of the outer surface is preferably 7.6 μm or less.

[0023] The arithmetic mean roughness (Ra) and the cut level difference (Rδc) can be measured in accordance with JIS B 0601:2001 using a laser microscope (Keyence Corporation, Ultra-Deep Color 3D Shape Measuring Microscope (VK-X1000 or its successor model)).

[0024] The measurement conditions are as follows: coaxial illumination, 120x magnification, no cutoff value λs, 0.08mm cutoff value λc, no cutoff value λf, and end effect correction. The measurement range per point on the inner surface of the holding member 3 to be measured is, for example, 2792 μm × 2093 μm, with two points set at both ends along the axial direction. For each measurement range, four lines are drawn at approximately equal intervals along the axial direction (the longitudinal direction for each measurement range), and the line roughness is measured. The length of each line to be measured is 2640 μm. The average values ​​of the arithmetic mean roughness (Ra) and the cut level difference (Rδc) are calculated based on the respective measurements obtained for each line.

[0025] The average values ​​of the arithmetic mean roughness (Ra) and the cut level difference (Rδc) of the outer surface of the insulating member 2 can also be determined in the same manner as described above.

[0026] The gap G between the inner surface forming the expanded diameter portion 31 of the holding member 3 and the outer surface of the insulating member 2 facing the inner surface is preferably 2 mm or less. Because the gap G is narrow in this way, the flow rate of corrosive gas leaking from this gap G can be reduced. The expanded diameter portion 31 has inclined surfaces on both sides in the axial direction that are inclined with respect to the axial direction. Therefore, stress concentration on both sides of the expanded diameter portion 31 can be reduced compared to when both sides are orthogonal surfaces perpendicular to the axial direction.

[0027] The first brazing portion 33 is located in the space on the opposite side (i.e., low-pressure side A2) from the space on the side where the thermal control element is installed (i.e., high-pressure side A1). Therefore, it is difficult for the corrosive gas moving from the high-pressure side A1 to the low-pressure side A2 to come into contact with the first brazing portion 33, and high bonding strength and high airtightness can be maintained for a long period of time.

[0028] At the first brazing portion 33, the insulating member 2 has a metallized layer 4 on its outer surface facing the first brazing portion 33. The metallized layer 4 may have extending portions 41, 41 extending beyond both axial ends of the first brazing portion 33 in a cross-sectional view parallel to the axial direction of the insulating member 2. When the metallized layer 4 has the extending portions 41, 41, the reliability of the joint is improved compared to when the extending portions 41, 41 are not provided.

[0029] The metallization layer 4 is formed, for example, by the following procedure. First, a metal paste containing at least one metal powder selected from the group consisting of tungsten (W), molybdenum (Mo), and manganese (Mn) as a main component is applied to the outer surface of the insulating member 2. The metallization layer 4 is then formed by firing the paste at approximately 1300°C in a hydrogen atmosphere (e.g., a mixed gas of 75% hydrogen gas and 25% nitrogen gas). Note that the surface of the metallization layer 4 may be plated with Ni to a thickness of approximately 1 μm to 3 μm to improve wettability with the brazing filler metal and reduce oxidation of the metal contained in the metal paste. The thickness of the metallization layer 4 is, for example, 10 μm to 50 μm.

[0030] As the brazing material, for example, Ag-Cu brazing material (BAg-8, BAg-8A, BAg-8B) can be used. The insulating member 2 and the holding member 3 are brazed together at about 800°C using a brazing material such as Ag-Cu brazing material to obtain the joined body 1, which is the airtight terminal of this embodiment.

[0031] The assembly 1 of this embodiment is used, for example, as an airtight terminal in a corrosive gas treatment device (purification device) that requires high airtightness. The corrosive gas treatment device is mounted on a vehicle or the like and can greatly contribute to purifying exhaust gases, etc.

[0032] Next, another embodiment of the present disclosure will be described with reference to Fig. 2. Note that the same components as those in Fig. 1 are designated by the same reference numerals and will not be described again. The joined body 10 shown in Fig. 2 is used as an airtight terminal, similar to the above-described embodiment.

[0033] As shown in Fig. 2, the joined body 10 includes a cylindrical insulating member 2 containing ceramics, a holding member 5 that surrounds the insulating member 2 and holds the insulating member 2, and a sleeve 6 that is disposed between the insulating member 2 and the holding member 5. The holding member 5 has an expanded diameter portion 51 that expands its inner diameter. The insulating member 2 and the sleeve 6 are joined at a first brazing portion 7. The holding member 5 and the sleeve 6 are joined at a second brazing portion 8.

[0034] The insulating member 2 has a through hole 21 that penetrates in the axial direction, and a conductive member that introduces current to a thermal control element such as a heater is located within this through hole 21. The first brazed portion 7 and the second brazed portion 8 are located in the space on the low-pressure side A2, which is opposite the space on the high-pressure side A1 where the thermal control element is installed. Because the first brazed portion 7 and the second brazed portion 8 are formed in positions away from the thermal control element, they are less susceptible to the effects of corrosive gas leaking from the gap between the holding member 5 and the insulating member 2, and airtightness is maintained for a long period of time.

[0035] The holding member 5 has a contact portion 9 on the axially opposite side of the first brazing portion 7, with the inner surface of the holding member 5 contacting the outer surface of the insulating member 2. A gap G between the inner surface of the holding member 5 that forms the expanded diameter portion 51 and the outer surface of the insulating member 2 that faces the inner surface may be 2 mm or less. When this gap G is 2 mm or less, the flow rate of corrosive gas leaking from the gap G is reduced.

[0036] The sleeve 6 has a bent portion 61 whose diameter decreases from the second brazed portion 8 toward the first brazed portion 7. This creates a space (i.e., an internal space formed by the expanded diameter portion 51) among the holding member 5, the insulating member 2, and the sleeve 6, thereby mitigating stress concentration.

[0037] The bent portion 61 is preferably inclined with respect to the axial direction of the insulating member 2. This reduces stress concentration at both ends of the bent portion 61 compared to when the bent portion 61 is perpendicular to the axial direction. The thickness of the sleeve 6 is preferably 0.3 mm or more and 0.7 mm or less.

[0038] The insulating member 2 is made of, for example, alumina (Al ２ O ３The retaining member 5 may include ceramics such as titanium (Ti), titanium alloys, molybdenum (Mo), copper (Cu), nickel (Cu), copper (Cu), iron (Fe), copper-based (Co), copper-copper-carbon (Fe), nickel-based (Co), nickel-based (Ni), nickel-based (Fe), nickel-based (Ni ...

[0039] The linear expansion coefficients of the holding member 5, sleeve 6, and insulating member 2 can be selected in this order so that they decrease with an appropriate difference. Also, the difference in the linear expansion coefficients between the holding member 5 and sleeve 6, and the difference in the linear expansion coefficients between the sleeve 6 and insulating member 2 can be selected so that they decrease in this order. This applies an appropriate compressive force to the insulating member 2, improving airtightness. Furthermore, if the sleeve 6 is made of an elastically deformable material, it applies pressure to both the insulating member 2 and the holding member 5. As a result, the reliability of the joint is improved.

[0040] The insulating member 2 has a metallized layer 11 on its outer surface facing the first brazing portion 7. In a cross-sectional view parallel to the axial direction of the insulating member 2, the metallized layer 11 extends beyond both axial ends of the first brazing portion 7. This improves the reliability of the joint compared to when the metallized layer 11 does not extend beyond both axial ends of the first brazing portion 7.

[0041] The first brazing portion 7 may be formed over the entire surface of the contact area between the insulating member 2 and the sleeve 6, or only a part of it. Similarly, the second brazing portion 8 may be formed over the entire surface of the contact area between the holding member 5 and the sleeve 6, or only a part of it. The brazing material used to form the first brazing portion 7 and the second brazing portion 8 may be the Ag-Cu brazing filler metal (BAg-8, BAg-8A, BAg-8B) as described above. The rest is the same as in the above-described embodiment.

[0042] As described above, in the joined bodies 1 and 10 of the present embodiment, when a corrosive gas moves from one side (e.g., the high-pressure side A1) to the other side (e.g., the low-pressure side A2), the first brazed portions 7 and 33 are located in positions that are difficult for the corrosive gas to come into contact with. As a result, the joined bodies 1 and 10 can maintain high joint strength and high airtightness for a long period of time. Therefore, the joined bodies 1 and 10 do not require a large space like conventional airtight terminals.

[0043] The insulating member in the present disclosure is not limited to the cylindrical shape shown in FIGS. 1 and 2 , but may be, for example, insulating members 12, 13, 14 containing columnar, pyramidal, or frustum-shaped ceramics, as shown in FIGS. 3A to 3C . FIGS. 3A to 3C show a bonded assembly including insulating members 12, 13, 14 and holding members 15, 16, 17 that surround the insulating members 12, 13, 14 and have an expanded diameter portion that expands the inner diameter. Such a bonded assembly can be used as an electromagnetic wave transmission window member for introducing electromagnetic waves into semiconductor manufacturing equipment or for outputting high-frequency waves from an accelerator. Other aspects are the same as those of the previously described embodiment, so detailed description will be omitted.

[0044] Furthermore, the application of the bonded body of the present disclosure is not limited to airtight terminals, but can also be used in, for example, discharge tubes with holders, insulators, vacuum switches, vacuum containers, and the like.

[0045] When the assembly is a discharge tube with a holder, the discharge tube with a holder is, for example, a component constituting a reactor for purifying exhaust gas generated in an internal combustion engine. In this case, the discharge tube with a holder includes a discharge tube having a cylindrical insulating tube and an annular holding member that holds the discharge tube on its outer periphery.

[0046] When the joined body is an insulator, the insulator is used in, for example, scientific and chemical equipment such as a vacuum device, an accelerator, etc. In this case, the insulator includes a holding member having a pair of annular base portions arranged opposite each other and annular wall portions having enlarged diameter portions whose inner diameters increase on the main surfaces of the opposing base portions, and a cylindrical insulating member having outer surfaces at both ends joined to the inner surfaces of the wall portions.

[0047] When the junction is a vacuum switch, it is used in scientific and laboratory equipment, and its structure is the same as that of the insulator described above.

[0048] When the joined body is a vacuum vessel, the vacuum vessel is, for example, a vessel for housing a lens for an electron microscope. In this case, the vacuum vessel includes a disk-shaped insulating member (window portion) containing ceramics and a bottomed, cylindrical holding member (main body portion) having an expanded diameter portion whose inner diameter expands. The vacuum vessel has, on one side of the expanded diameter portion, an abutment portion where the outer surface of the insulating member abuts against the inner surface of the holding member, and a first brazing portion on the other side that joins the outer surface of the insulating member to the inner surface of the holding member.

[0049] Whether the joint is a discharge tube with a holding portion, an insulator, a vacuum switch, or a vacuum vessel, it has an abutment portion on one side where the outer surface of the insulating member abuts against the inner surface of the holding member, and a first brazing portion on the other side that joins the outer surface of the insulating member to the inner surface of the holding member, sandwiching an expanded diameter portion provided on the holding member.

[0050] Alternatively, the device may include a retaining member that surrounds the insulating member and has an expanded diameter portion that widens its inner diameter, and a sleeve that is placed between the insulating member and the retaining member, and may have a first brazing portion that joins the insulating member and the sleeve, and a second brazing portion that joins the retaining member and the sleeve.

[0051] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications and improvements are possible within the scope of the present disclosure.

[0052] REFERENCE SIGNS LIST 1, 10 Joint 2 Insulating member 21 Through hole 3 Holding member 31 Expanded diameter portion 32 Contact portion 33 First brazed portion 4 Metallized layer 41 Extension portion 5 Holding member 51 Expanded diameter portion 6 Sleeve 61 Bent portion 7 First brazed portion 8 Second brazed portion 9 Contact portion 11 Metallized layer 12, 13, 14 Insulating member 15, 16, 17 Holding member A1 High-voltage side A2 Low-voltage side

Claims

1. An insulating member including a ceramic; a holding member surrounding the insulating member and having an expanded diameter portion whose inner diameter expands; Equipped with a contact portion where an outer surface of the insulating member and an inner surface of the holding member contact each other, and a first brazing portion that joins the outer surface of the insulating member and the inner surface of the holding member, A joint, wherein the abutment portion and the first brazing portion are positioned with the expanded diameter portion therebetween.

2. An insulating member including a ceramic; a holding member surrounding the insulating member and having an expanded diameter portion whose inner diameter expands; a sleeve disposed between the insulating member and the holding member; Equipped with a first brazing portion that joins the insulating member and the sleeve; a second brazing portion that joins the retaining member and the sleeve; A zygote having the structure

3. The joint assembly according to claim 2 , further comprising an abutment portion on the opposite side of the first brazing portion across the enlarged diameter portion, where an inner surface of the holding member abuts against an outer surface of the insulating member.

4. The joint assembly according to claim 2 or 3, wherein the sleeve has a bent portion whose diameter decreases from the second brazed portion toward the first brazed portion.

5. The joined body according to claim 4 , wherein the bent portion is inclined with respect to an axial direction of the insulating member.

6. The assembly of claim 2 or 3, wherein the sleeve comprises an elastically deformable material.

7. 3. The joined body according to claim 1, wherein the retaining member comprises Ti, a Ti alloy, Mo, Cu-Ni, Cu, an Fe-Co based alloy, an Fe-Co-C based alloy, an Fe-Ni based alloy, an Fe-Ni-Co based alloy, a ferritic stainless steel, a martensitic stainless steel, an austenitic stainless steel, or a nickel-based superalloy.

8. 4. The joint body according to claim 2, wherein the sleeve contains Ti, a Ti alloy, Mo, Cu-Ni, Cu, an Fe-Co based alloy, an Fe-Co-C based alloy, an Fe-Ni based alloy, or an Fe-Ni-Co based alloy.

9. 2. The joined body according to claim 1, wherein a gap between an inner surface forming the enlarged diameter portion of the holding member and an outer surface of the insulating member opposing the inner surface is 2 mm or less.

10. The joint body described in claim 1 or 2, wherein the insulating member has a metallized layer facing the first brazing portion, and the metallized layer extends beyond both axial ends of the first brazing portion in a cross-sectional view parallel to the axial direction of the insulating member.

11. The joined body according to claim 1 or 2, wherein the insulating member comprises a ceramic having a cylindrical, columnar, pyramidal or frustum shape.

12. 3. The joint assembly according to claim 1, wherein the insulating member includes a cylindrical ceramic having a through hole in the axial direction, and at least a portion of a conductive member for introducing a current to the thermal control element is located in the through hole.

13. The joint body according to claim 12 , wherein the first brazing portion is located in a space opposite to a space on a side where the thermal control element is provided.

14. The insulating member includes a cylindrical ceramic having a through hole in the axial direction, and at least a part of a conductive member that introduces a current to the thermal control element is located in the through hole, The bonded body according to claim 2 or 3, wherein the first brazing portion and the second brazing portion are located in a space opposite to a space on a side where the thermal control element is provided.

15. A corrosive gas treatment device comprising the joined body according to claim 1 or 2.

16. A tractor equipped with the corrosive gas treatment device according to claim 15.