EP0376579A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
One-end closed ceramic double tube and method of manufacturing the same
Assignee: NGK Insulators Ltd
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Filing: 1989-12-19
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Granted: —
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Expires: 2009-12-19
Abstract
Abstract A one-end closed ceramic double tube has an integral structure comprising: a one-end closed outer cylinder (3); an inner cylinder (2) concentric with said outer cylinder; and at least one support portion (4-1,4-2) extending laterally to bridge said outer and inner cylinders and longitudinally from near the closed end at least up to the open end of said outer cylinder, wherein the ratio of a total thickness of the support portions in contact with the inner circumference of the outer cylinder to the inner circumference of the outer cylinder at cross section is at most 25%, and preferably, the outside diameter ratio of the outer cylinder to the inner cylinder is at most 3.3. An air passage formed on the inner cylinder near the closed end side of the tube communicates between the inner passageway inside the inner cylinder and the outer passageway defined by the inner and outer cylinders. This double tube has high reliability and sufficient mechanical strength and can be suitably used as filters, heat exchangers, concentrators and as supporting tubes for fuel cells. This double tube is manufactured by means of extrusion molding.
Inventors
- 👤 Hidenobu 6-1207 Onoe Danchi Misawa
- 👤 Satoru Yamada
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 05:57
CPC Classifications
F; F28; F28D; F28D7/00; F28D7/10; F28D7/12; B; B01; B01D; B01D29/00; B01D29/11; B01D29/111; B01D29/31; B28; B28B; B28B11/00; B28B11/003; B28B11/006; B28B7/00; B28B7/34; B28B7/342; F28F; F28F21/00; F28F21/04; H; H01; H01M; H01M8/00; H01M8/10; H01M8/12; H01M8/1231; Y; Y02; Y02E; Y02E60/00; Y02E60/30; Y02E60/50; Y02P; Y02P70/00; Y02P70/50
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
162 words
A one-end closed ceramic double tube comprising: a one-end closed outer cylinder; an inner cylinder having an outside diameter smaller than the inside diameter of said outer cylinder and extending concentrically with said outer cylinder from the vicinity of the closed end at least up to the open end of the outer cylinder; and at least one support portion extending centripetally from the inner periphery of the outer cylinder to connect with the outer periphery of the inner cylinder and longitudinally from one end of the inner cylinder on the closed end side of the outer cylinder at least up to the open end of said outer cylinder; said outer cylinder, inner cylinder and support portion being formed integrally into one body from a ceramic material, wherein the ratio of a total thickness of the support portions in contact with the inner circumference of the outer cylinder to the inner circumference of the outer cylinder at cross section is at most 25%.
Claim 2
Dependent Claim
162 words
A one-end closed ceramic double tube comprising: a one-end closed outer cylinder; an inner cylinder having an outside diameter smaller than the inside diameter of said outer cylinder and extending concentrically with said outer cylinder from the vicinity of the closed end at least up to the open end of the outer cylinder; and at least one support portion extending centripetally from the inner periphery of the outer cylinder to connect with the outer periphery of the inner cylinder and longitudinally from one end of the inner cylinder on the closed end side of the outer cylinder at least up to the open end of said outer cylinder; said outer cylinder, inner cylinder and support portion being formed integrally into one body from a ceramic material, wherein the ratio of a total thickness of the support portions in contact with the inner circumference of the outer cylinder to the inner circumference of the outer cylinder at cross section is at most 25%.
Claim 3
Dependent Claim
21 words
The double tube according to claim 1, wherein the inner cylinder extends longitudinally beyond the open end of the outer cylinder.
Claim 4
Dependent Claim
67 words
The double tube according to claim 1, wherein the inner cylinder on the closed end side of the outer cylinder is close to or in contact with the closed end of the outer cylinder and said one end of the inner cylinder is provided with at least one air passage communicating the inner space of the inner cylinder with the gap between the inner and outer cylinders.
Claim 5
Dependent Claim
18 words
The double tube according to claim 1, wherein the inner cylinder is formed denser than the outer cylinder.
Claim 6
Dependent Claim
149 words
A one-end closed ceramic double tube comprising: a one-end closed outer cylinder; an inner cylinder having an outside diameter smaller than the inside diameter of said outer cylinder and extending concentrically with said outer cylinder from the vicinity of the closed end at least up to the open end of the outer cylinder; and at least one support portion extending centripetally from the inner periphery of the outer cylinder to connect with the outer periphery of the inner cylinder and longitudinally from one end of the inner cylinder on the closed end side of the outer cylinder at least up to the open end of said outer cylinder; said outer cylinder, inner cylinder and support portion being formed integrally into one body from a ceramic material, wherein the ratio of the outside diameter of the outer cylinder to the outside diameter of the inner cylinder is at most 3.3.
Claim 7
Dependent Claim
149 words
A one-end closed ceramic double tube comprising: a one-end closed outer cylinder; an inner cylinder having an outside diameter smaller than the inside diameter of said outer cylinder and extending concentrically with said outer cylinder from the vicinity of the closed end at least up to the open end of the outer cylinder; and at least one support portion extending centripetally from the inner periphery of the outer cylinder to connect with the outer periphery of the inner cylinder and longitudinally from one end of the inner cylinder on the closed end side of the outer cylinder at least up to the open end of said outer cylinder; said outer cylinder, inner cylinder and support portion being formed integrally into one body from a ceramic material, wherein the ratio of the outside diameter of the outer cylinder to the outside diameter of the inner cylinder is at most 3.3.
Claim 8
Dependent Claim
35 words
The double tube according to claim 5, wherein the ratio of the total thickness of the support portions in contact with the inner circumference of the outer cylinder at cross section is at most 25%.
Claim 9
Dependent Claim
21 words
The double tube according to claim 5, wherein the inner cylinder extends longitudinally beyond the open end of the outer cylinder.
Claim 10
Dependent Claim
67 words
The double tube according to claim 5, wherein the inner cylinder on the closed end side of the outer cylinder is close to or in contact with the closed end of the outer cylinder and said one end of the inner cylinder is provided with at least one air passage communicating the inner space of the inner cylinder with the gap between the inner and outer cylinders.
Claim 11
Dependent Claim
18 words
The double tube according to claim 5, wherein the inner cylinder is formed denser than the outer cylinder.
Claim 12
Independent Claim
190 words
A method for manufacturing a one-end closed ceramic double tube, which comprises the steps of: (1) extruding a ceramic material from a die having outer slits arranged in circular, inner slits arranged concentrically therewith and at least one slit extending centripetally from said outer slit to said inner slit, thereby to mold a double tube consisting of an outer cylinder and an inner cylinder arranged concentrically and connected integrally therewith by at least one support portion, which outer and inner cylinders and support portion extend uniformly along the longitudinal axis of the double tube; (2) drying the above extrusion-molded double tube; (3) forming a passage communicating the inner space of the inner cylinder with the gap between the inner and outer cylinders at one end of the inner cylinder and sealing one end of the outer cylinder on the passage formed side of the inner cylinder; (4) grinding the outer cylinder and optionally at least a part of the support portion by a predetermined length along the longitudinal axis from the open end of the double tube to thereby protrude the inner cylinder from the outer cylinder; and (5) firing.
Claim 13
Independent Claim
190 words
A method for manufacturing a one-end closed ceramic double tube, which comprises the steps of: (1) extruding a ceramic material from a die having outer slits arranged in circular, inner slits arranged concentrically therewith and at least one slit extending centripetally from said outer slit to said inner slit, thereby to mold a double tube consisting of an outer cylinder and an inner cylinder arranged concentrically and connected integrally therewith by at least one support portion, which outer and inner cylinders and support portion extend uniformly along the longitudinal axis of the double tube; (2) drying the above extrusion-molded double tube; (3) forming a passage communicating the inner space of the inner cylinder with the gap between the inner and outer cylinders at one end of the inner cylinder and sealing one end of the outer cylinder on the passage formed side of the inner cylinder; (4) grinding the outer cylinder and optionally at least a part of the support portion by a predetermined length along the longitudinal axis from the open end of the double tube to thereby protrude the inner cylinder from the outer cylinder; and (5) firing.
Claim 14
Dependent Claim
122 words
The method according to claim 10, wherein said step (3) comprises the sub-steps of: (a) grinding the inner cylinder and the support portion by a predetermined axial length from one end of the double tube; (b) inserting a cap made of a burnable organic material, having a rim diameter substantially equal to the inside diameter of the outer cylinder into said one end of the double tube, directing the convex top of the cap outwards; and (c) filling a space defined by the convex top surface of the cap and the outer cylinder at said one end with a slip which yields a ceramic having a thermal expansion coefficient at firing substantially equal to that of the double tube, followed by drying.
Claim 15
Dependent Claim
70 words
The method according to claim 10, wherein said step (3) comprises the sub-steps of: (a′) removing one end of the inner cylinder by a predetermined axial length from one end of the double tube; and (b′) fixing a ceramic sealing member, preferably of the same material as the outer cylinder, on said one end of the double tube with a ceramic slip, preferably of said same material, followed by drying.
Claim 16
Dependent Claim
49 words
The method according to claim 10, which further comprises, after said step (2), the step (2′) of pouring a slip of fine particulate into the inner cylinder, followed by discharging said slip, thereby to form a fine particulate slip layer over the inner peripheral surface of the inner cylinder.
Claim 17
Dependent Claim
178 words
A ceramic double tube comprising: an outer tube with one closed end; at least one inner tube having a maximum outside dimension smaller than the maximum inside dimension of said outer tube and extending longitudinally along said outer tube from the vicinity of the closed end at least up to the open end of the outer tube; and for each said inner tube at least one support region or element connecting the inner periphery of the outer tube to the outer periphery of the inner tube and extending longitudinally from one end of the inner tube at the closed end of the outer tube at least up to the open end of the outer tube; said outer tube, each inner tube and each support region portion being formed integrally in one body from a ceramic material, wherein as seen in transverse cross-section the ratio of the total circumferential thickness of the support regions or portions at the inner periphery of the outer tube to the length of the inner periphery of the outer tube is at most 25%.
Claim 18
Dependent Claim
178 words
A ceramic double tube comprising: an outer tube with one closed end; at least one inner tube having a maximum outside dimension smaller than the maximum inside dimension of said outer tube and extending longitudinally along said outer tube from the vicinity of the closed end at least up to the open end of the outer tube; and for each said inner tube at least one support region or element connecting the inner periphery of the outer tube to the outer periphery of the inner tube and extending longitudinally from one end of the inner tube at the closed end of the outer tube at least up to the open end of the outer tube; said outer tube, each inner tube and each support region portion being formed integrally in one body from a ceramic material, wherein as seen in transverse cross-section the ratio of the total circumferential thickness of the support regions or portions at the inner periphery of the outer tube to the length of the inner periphery of the outer tube is at most 25%.
Claim 19
Dependent Claim
34 words
Use of a double tube according to any one of claims 1 to 9 and 14 or produced by a method according to any one of claims 10 to 13, in a fuel cell.
References Cited (Backward Citations)
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