CA1137159A - Cap seal for resilient electrical housing - Google Patents
Cap seal for resilient electrical housingInfo
- Publication number
- CA1137159A CA1137159A CA000344922A CA344922A CA1137159A CA 1137159 A CA1137159 A CA 1137159A CA 000344922 A CA000344922 A CA 000344922A CA 344922 A CA344922 A CA 344922A CA 1137159 A CA1137159 A CA 1137159A
- Authority
- CA
- Canada
- Prior art keywords
- housing
- flange
- cap
- passage
- arrestor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H69/00—Apparatus or processes for the manufacture of emergency protective devices
- H01H69/02—Manufacture of fuses
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
- H01C1/024—Housing; Enclosing; Embedding; Filling the housing or enclosure the housing or enclosure being hermetically sealed
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
- H01C7/12—Overvoltage protection resistors
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Connector Housings Or Holding Contact Members (AREA)
- Gasket Seals (AREA)
- Casings For Electric Apparatus (AREA)
- Gas-Insulated Switchgears (AREA)
- Insulators (AREA)
- Thermistors And Varistors (AREA)
Abstract
CAP SEAL FOR RESILIENT ELECTRICAL HOUSING
ABSTRACT
A gapless arrestor having an elastomeric housing and a number of surge arrestor blocks positioned within a passage within the housing, an electrically conductive terminating cap provided at one end of the housing to close the passage, the terminating cap being compressed by magnetic pulse forming against the outer surface of the housing to hermetically seal the passage, the cap also including an electrically conductive contact engaging the end of a surge arrestor block, ridges can be molded around the outer surface of the housing to interlock with the flange of the terminating cap to act as "O" ring seals and to hold the cap on the housing. A
rigid ring can be placed in a groove provided at the end of the passage adjacent to the cap which cooperates with the flange to provide an even compression of the elastomeric housing.
ABSTRACT
A gapless arrestor having an elastomeric housing and a number of surge arrestor blocks positioned within a passage within the housing, an electrically conductive terminating cap provided at one end of the housing to close the passage, the terminating cap being compressed by magnetic pulse forming against the outer surface of the housing to hermetically seal the passage, the cap also including an electrically conductive contact engaging the end of a surge arrestor block, ridges can be molded around the outer surface of the housing to interlock with the flange of the terminating cap to act as "O" ring seals and to hold the cap on the housing. A
rigid ring can be placed in a groove provided at the end of the passage adjacent to the cap which cooperates with the flange to provide an even compression of the elastomeric housing.
Description
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BACKGROUND OF INVENTION
A gapless arrestor of the type contemplated herein is disclosed in Canadian Patent 1,118,835 entitled "GAPLESS ELBOW ARRESTOR" issued February 23, 1982. As disclosed therein the voltage surge arrestor blocks are housed within a passage in an elastomeric or rubber housing to cushion and protect the ceramic parts which form the arrestor blocks from damage. However, the inherent resiliency of the elastomeric housing required that the terminal connector be provided on the internal part of the housing because of the insufficient compressive strength of the housing to secure the terminal to the exterior surface.
Magnetic pulse forming has been used to secure metallic members to non-metallic members made of relatively rigid materials such as Bakelite (Trade mark) and/or ceramics which are relatively brittle. This method is described in U.S.Patent 4,063,208 granted on December 13, 1977 and entitled "Fuse Housing End Caps Secured by Magnetic Pulse Forming". The cylindrical housing of the type disclosed in this patent has sufficient compressive strength to resist the forces of the magnetic pulses in forming the flange of the end cap to the exterior surface of the end of the hosuing.
SUMMARY OF THE INVENTION
The method for securing an end cap to an elastomeric housing as disclosed in the present invention utilizes the capability of magnetic pulse forming to both secure and obtain a hermetic seal between a terminal cap ;
and an elastomeric housing. The hermetic seal is achieved by the even distribution of the compressive force of the magnetic pulses to the flange of the cap around the entire perimeter of the end of the housing.
The hermetic seal has been further improved by providing ridges around the end of the elastomeric housing which engage the internal surface of the flange of the terminal cap. When the magnetic pulses necessary to form the flange against the housing are applied to the flange, the ridges form "O"-rings which bear against the flange to produce the seal. It has been further found that by providing a rigid ring on the inside surface of the housing, the compressive strength of the housing can be increased whereby magnetic pulse forming of the flange will compress the housing between the ring and the flange to produce the hermetic seal.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross sectional view of a portion of the open end of a gapless arrestor showing the terminal cap in a position to be pushed onto the end of the elastomeric nousing.
Figure 2 is a cross sectional view of a portion of the gapless arrestor showing the terminal cap in position for magetically pulse forming to the housing.
Figure 3 is a cross sectional view of a portion of the arrestor similar to Figure 2 showing the terminal cap after being magnetically pulse formed to the housing.
Figure 4 is a cross sectional view of an alternate form of gapless arrestor having a rigid ring positioned in a groove on the inside surface of the open end of the arrestor housing.
DESCRIPTION OF THE INVENTION
Referring to Figure 1, a portion of a gapless elbow arrestor 10 is shown. The arrestor includes an elastomeric housing 12 molded from a material such as rubber which is shown in a generally cylindrical form having an inner insulating portion 14 and an outer semi-conductive portion 13. A central passage 18 is provided within the insulating portion 14 and a number of annular ridges 15 are molded around the outside surface of the semi-conductive portion 13 at the open end of the housing 12. Surge arrestor means in the form of a number of surge arrestor blocks 16 are shown positioned within the passage 18.
The open end of the passage 18 is closed by means of a terminal cap 20 which Includes a generally, flat end-plate 22 and an annular flange 24. The flange 24 has a diameter substantially equal to the diameter of the ridges 15 provided on the outside surface of the housing.
Means can be provided in the terminal cap for electrically engaging the surge arrestor blocks 16. Such means is shown in the form of a threaded stud 26 which is welded to an indent 28 provided in the end wall 22.
Indent 28 projecting inward sufficiently to engage the end of the surge arrestor block at the end of the passage 18.
~i37159 Figure 2 shows the terminal cap 20 positioned on the end of the housing 12 prior to magnetic pulse forming. It should be noted that the annular ridges 15 are shown in contact with the inside surface of the flange 24. However, if ridges 15 are not provided the flange diameter should be made slightly greater than the diameter of the housing 12.
Figure 3 shows the terminal cap 20 after being pulse formed into engagement with the outside surface of the elastomeric housing. The ridges 15 which have a greater diameter than the outside surface of the housing resist the compressor force imposed by magnetic pulse forming the flange in the end cap against the housing causing the flange to form around the rings and interlock therewith. The rings for an annular pressure line against the inside surface of the flange 24 providing a means for securing the end cap into the housing. These pressure lines also form seal rings and thus act as O-ring seals to seal the terminal cap to the elastomeric housing.
In the alternate embodiment of the invention shown in Figure 4 means are provided to increase the compressive strength of the housing. Such means is in the form of a rigid ring 30 positioned in a groove 32 provided on the inner surface of the insulating portion 14 at the open end of the passage 18 in the housing. The ring provides sufficient compressive restraint to the housing to prevent distortion of the housing due to the magnetic pulse force applied to the flange 24 of the terminal cap. The portion of the elastomeric housing ~13715~
between the rigid ring 32 and the flange 24 is compressed evenly to form the hermetic seal and to lock the flange to the ridges on the end of the housing.
In Figure 4 it should be further noted that the surge arrestor block 16 is biased by means of a spring 34 provided between the cap 20 and the last block 16. The ability of the end cap 20 to interlock with the ridges 15 when magnetically pulse formed to the house makes this possible. The flange 24 will form around the ridges 15 as shown in Figures 3 and 4 to securely hold the cap 20 in position.
RESUME
Magnetic pulse forming of a deformable member to an elastomeric housing is believed to be one of the unique features of this application. Attachment of end caps to flexible tubular housings has always been difficult if not impossible by conventional rolling methods. The ability to provide a moisture seal between the end cap and the elastomeric housing is also a feature which is unique in this application. The moisture seal being improved by the adaption of annular ridges on the outside surface of housing which engage the inside surface of flange of the end cap.
BACKGROUND OF INVENTION
A gapless arrestor of the type contemplated herein is disclosed in Canadian Patent 1,118,835 entitled "GAPLESS ELBOW ARRESTOR" issued February 23, 1982. As disclosed therein the voltage surge arrestor blocks are housed within a passage in an elastomeric or rubber housing to cushion and protect the ceramic parts which form the arrestor blocks from damage. However, the inherent resiliency of the elastomeric housing required that the terminal connector be provided on the internal part of the housing because of the insufficient compressive strength of the housing to secure the terminal to the exterior surface.
Magnetic pulse forming has been used to secure metallic members to non-metallic members made of relatively rigid materials such as Bakelite (Trade mark) and/or ceramics which are relatively brittle. This method is described in U.S.Patent 4,063,208 granted on December 13, 1977 and entitled "Fuse Housing End Caps Secured by Magnetic Pulse Forming". The cylindrical housing of the type disclosed in this patent has sufficient compressive strength to resist the forces of the magnetic pulses in forming the flange of the end cap to the exterior surface of the end of the hosuing.
SUMMARY OF THE INVENTION
The method for securing an end cap to an elastomeric housing as disclosed in the present invention utilizes the capability of magnetic pulse forming to both secure and obtain a hermetic seal between a terminal cap ;
and an elastomeric housing. The hermetic seal is achieved by the even distribution of the compressive force of the magnetic pulses to the flange of the cap around the entire perimeter of the end of the housing.
The hermetic seal has been further improved by providing ridges around the end of the elastomeric housing which engage the internal surface of the flange of the terminal cap. When the magnetic pulses necessary to form the flange against the housing are applied to the flange, the ridges form "O"-rings which bear against the flange to produce the seal. It has been further found that by providing a rigid ring on the inside surface of the housing, the compressive strength of the housing can be increased whereby magnetic pulse forming of the flange will compress the housing between the ring and the flange to produce the hermetic seal.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross sectional view of a portion of the open end of a gapless arrestor showing the terminal cap in a position to be pushed onto the end of the elastomeric nousing.
Figure 2 is a cross sectional view of a portion of the gapless arrestor showing the terminal cap in position for magetically pulse forming to the housing.
Figure 3 is a cross sectional view of a portion of the arrestor similar to Figure 2 showing the terminal cap after being magnetically pulse formed to the housing.
Figure 4 is a cross sectional view of an alternate form of gapless arrestor having a rigid ring positioned in a groove on the inside surface of the open end of the arrestor housing.
DESCRIPTION OF THE INVENTION
Referring to Figure 1, a portion of a gapless elbow arrestor 10 is shown. The arrestor includes an elastomeric housing 12 molded from a material such as rubber which is shown in a generally cylindrical form having an inner insulating portion 14 and an outer semi-conductive portion 13. A central passage 18 is provided within the insulating portion 14 and a number of annular ridges 15 are molded around the outside surface of the semi-conductive portion 13 at the open end of the housing 12. Surge arrestor means in the form of a number of surge arrestor blocks 16 are shown positioned within the passage 18.
The open end of the passage 18 is closed by means of a terminal cap 20 which Includes a generally, flat end-plate 22 and an annular flange 24. The flange 24 has a diameter substantially equal to the diameter of the ridges 15 provided on the outside surface of the housing.
Means can be provided in the terminal cap for electrically engaging the surge arrestor blocks 16. Such means is shown in the form of a threaded stud 26 which is welded to an indent 28 provided in the end wall 22.
Indent 28 projecting inward sufficiently to engage the end of the surge arrestor block at the end of the passage 18.
~i37159 Figure 2 shows the terminal cap 20 positioned on the end of the housing 12 prior to magnetic pulse forming. It should be noted that the annular ridges 15 are shown in contact with the inside surface of the flange 24. However, if ridges 15 are not provided the flange diameter should be made slightly greater than the diameter of the housing 12.
Figure 3 shows the terminal cap 20 after being pulse formed into engagement with the outside surface of the elastomeric housing. The ridges 15 which have a greater diameter than the outside surface of the housing resist the compressor force imposed by magnetic pulse forming the flange in the end cap against the housing causing the flange to form around the rings and interlock therewith. The rings for an annular pressure line against the inside surface of the flange 24 providing a means for securing the end cap into the housing. These pressure lines also form seal rings and thus act as O-ring seals to seal the terminal cap to the elastomeric housing.
In the alternate embodiment of the invention shown in Figure 4 means are provided to increase the compressive strength of the housing. Such means is in the form of a rigid ring 30 positioned in a groove 32 provided on the inner surface of the insulating portion 14 at the open end of the passage 18 in the housing. The ring provides sufficient compressive restraint to the housing to prevent distortion of the housing due to the magnetic pulse force applied to the flange 24 of the terminal cap. The portion of the elastomeric housing ~13715~
between the rigid ring 32 and the flange 24 is compressed evenly to form the hermetic seal and to lock the flange to the ridges on the end of the housing.
In Figure 4 it should be further noted that the surge arrestor block 16 is biased by means of a spring 34 provided between the cap 20 and the last block 16. The ability of the end cap 20 to interlock with the ridges 15 when magnetically pulse formed to the house makes this possible. The flange 24 will form around the ridges 15 as shown in Figures 3 and 4 to securely hold the cap 20 in position.
RESUME
Magnetic pulse forming of a deformable member to an elastomeric housing is believed to be one of the unique features of this application. Attachment of end caps to flexible tubular housings has always been difficult if not impossible by conventional rolling methods. The ability to provide a moisture seal between the end cap and the elastomeric housing is also a feature which is unique in this application. The moisture seal being improved by the adaption of annular ridges on the outside surface of housing which engage the inside surface of flange of the end cap.
Claims (9)
1. An improved receptacle for an electrical apparatus, said receptacle including a cylindrical electri-cally insulating elastomeric housing formed from a compressible elastomeric material and having a passage and being open at one end, an electrically conductive metallic cap mounted on said housing and enclosing the open end of said passage, said cap having an annular flange encircling an end portion of the outer surface of the housing at the open end, said flange being compressed by magnetic pulse forming against the outer surface of said elastomeric housing to form a hermetic seal therewith and means for electrically connect-ing said cap to the apparatus.
2. The receptacle according to claim 1 wherein said housing includes an annular ridge molded around the outside surface of said housing, said flange being compressed against said ridge whereby said ridge forms a sealing ring between said housing and said flange.
3. The receptacle according to claim 1 wherein said housing includes a groove around the inner surface of the housing at the open end of said passage and a rigid ring positioned in said groove to provide sufficient compress-ive strength around the inner surface of the opening in said housing to provide an even compression of said housing on magnetic pulse forming of said flange to said housing.
4. A gapless arrestor comprising a compressible elastomeric housing having a passage open at one end, voltage sensitive surge means in said passage and an electrically conductive terminating cap mounted on said housing at said one end of said passage, said cap including an annular flange encircling an end portion of the outer surface of said housing, said flange being compressed by magnetic pulse forming against the outer surface of said housing to form a hermetic seal therewith.
5. The arrestor according to claim 4 wherein said cap includes means for electrically engaging said voltage sensitive means and being held in electrical contact therewith by the elastic force of said housing.
6. The arrestor according to claim 4 wherein said housing includes a groove around the inner surface of the passage adjacent to said terminal cap, a metallic ring positioned in said groove to increase the compressive strength of the housing around the passage whereby said ring cooperates with said flange on forming to provide an even compression of said housing.
7. The arrestor according to claims 4, 5 or 6 wherein said housing includes an annular ridge molded on the outside surface of said housing and said flange is formed around said ridge whereby said ridge forms a sealing ring between said flange and said housing.
8. The arrestor according to claim 4 wherein said housing includes means for securing said end cap to said housing.
9. The arrestor according to claim 8 wherein said means comprises a ridge molded around the outer surface of said housing, said flange on said end cap being formed around said ridge.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US3228879A | 1979-04-23 | 1979-04-23 | |
| US32,288 | 1979-04-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1137159A true CA1137159A (en) | 1982-12-07 |
Family
ID=21864125
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000344922A Expired CA1137159A (en) | 1979-04-23 | 1980-02-01 | Cap seal for resilient electrical housing |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0020010B1 (en) |
| JP (1) | JPS563986A (en) |
| AT (1) | ATE8438T1 (en) |
| CA (1) | CA1137159A (en) |
| DE (1) | DE3068502D1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56114302A (en) * | 1980-02-04 | 1981-09-08 | Rte Corp | Arrester block assembly |
| DE3334533A1 (en) * | 1983-09-23 | 1985-04-04 | Transformatoren Union Ag, 7000 Stuttgart | Surge arrester |
| DK173921B1 (en) * | 1986-01-29 | 2002-02-18 | Bowthorpe Ind Ltd | Electric surge arrester, method and apparatus for making and using such a device |
| JP2837978B2 (en) * | 1991-08-02 | 1998-12-16 | 日本碍子株式会社 | Lightning arrester and its manufacturing method |
| DE4319986A1 (en) * | 1993-06-11 | 1994-12-15 | Siemens Ag | Surge arresters |
| CN101882491B (en) * | 2010-06-17 | 2012-08-08 | 国网电力科学研究院 | Protective resistor for use in ultrahigh-voltage very fast transient overvoltage test |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB867901A (en) * | 1958-07-17 | 1961-05-10 | Westinghouse Electric Corp | Improvements in or relating to spark gap devices |
| US3631323A (en) * | 1970-06-09 | 1971-12-28 | Ralph R Pittman | Surge-modifying lightning arrester construction |
| US3727108A (en) * | 1972-02-15 | 1973-04-10 | Kearney National Inc | Surge arrester |
| US4028656A (en) * | 1975-11-19 | 1977-06-07 | S & C Electric Company | High voltage fuse with outer heat-shrinkable sleeve |
| US4063208A (en) * | 1975-11-19 | 1977-12-13 | S & C Electric Company | Fuse housing end caps secured by magnetic pulse forming |
| US4035753A (en) * | 1976-07-23 | 1977-07-12 | S & C Electric Company | Current limiting fuse construction |
-
1980
- 1980-02-01 CA CA000344922A patent/CA1137159A/en not_active Expired
- 1980-04-22 EP EP80301283A patent/EP0020010B1/en not_active Expired
- 1980-04-22 AT AT80301283T patent/ATE8438T1/en not_active IP Right Cessation
- 1980-04-22 DE DE8080301283T patent/DE3068502D1/en not_active Expired
- 1980-04-23 JP JP5407480A patent/JPS563986A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0020010A1 (en) | 1980-12-10 |
| EP0020010B1 (en) | 1984-07-11 |
| DE3068502D1 (en) | 1984-08-16 |
| JPS563986A (en) | 1981-01-16 |
| ATE8438T1 (en) | 1984-07-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |