EP0206406B1 - Two-part transformer casing having liquid-tight seal - Google Patents
Two-part transformer casing having liquid-tight seal Download PDFInfo
- Publication number
- EP0206406B1 EP0206406B1 EP19860201030 EP86201030A EP0206406B1 EP 0206406 B1 EP0206406 B1 EP 0206406B1 EP 19860201030 EP19860201030 EP 19860201030 EP 86201030 A EP86201030 A EP 86201030A EP 0206406 B1 EP0206406 B1 EP 0206406B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- casing
- cross
- section
- transformer casing
- flexible
- 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
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/02—Casings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D43/00—Lids or covers for rigid or semi-rigid containers
- B65D43/02—Removable lids or covers
- B65D43/12—Removable lids or covers guided for removal by sliding
Definitions
- the present invention relates to a transformer casing comprising a first casing part having an opening provided along its perifery with a first rigid member and a second member extending in a direction substantially parallel to said first rigid member at a predetermined distance therefrom and connected to said first rigid member at a first extremity thereof, said first and second member together forming a channel along the perifery of the opening having a substantially U-shaped cross section, and a second part having a shape substantially corresponding with that of the said opening and having along its perifery a projecting member adapted to be inserted into said channel.
- the standard two-part transformer casings now in use for high voltage transformers in the communications field consist of a main casing which has a groove or channel of rectangular cross-section into which the cover is slidably inserted.
- hot liquid potting material e.g. epoxy
- a vacuum to remove entrapped air.
- leakage around the casing-cover seal occurred frequently during this process.
- sealers or adhesives were necessary which added to the cost of production.
- US-A 4 273 406 shows a two part casing for a certain component in which the opening of the one part along its perifery is provided with portions having two rigid members forming a U-shaped channel there between and each of the portions being provided with a nose shaped projection extending at some distance from the casing body.
- the other casing part being provided with projecting members which can be inserted of the U-shaped channels on the other casing part and each projecting member having a nose portion which can cooperate with the nose portions on the other casing part sothat by turning the two casing parts with respect to each the two parts can coupled to each other.
- Such a locking arrangement does not provide a liquid tight seal between the two casing parts.
- the transformer casing is characterized in that the second member is flexible and said projecting member has a first portion clearing said flexible member and having a wedge-shaped cross section and a first surface for contacting said rigid member to form a first mechanical seal, said projecting member further having a second portion having a substantially rectangular cross section and a second surface for contacting said flexible member to form a back-up seal, wherein said first surface is at a second distance from said second surface which is at least equal to said predetermined distance and wherein said first and second part of said casing together constitute a housing containing hot potting compound.
- the flexible member exerts a sealing force onto the projecting member of the second part pressing it against the rigid member, thus creating a tight mechanical seal.
- a second or back-up seal is formed at the contact between the flexible member of the first part and the projecting member of the second part of the casing.
- the first part is molded as a single unit, the flexible member being a tapered beam having a substantially decreased cross section at the extremity contacting the projecting member of the second part.
- the transformer casing shown in an exploded view in Fig. 3 consists of a main casing (or first part) 10 and a cover (or second part) 12.
- the cover is to slide into the main body in the direction of the arrow. Since the body of the casing contains heated liquid epoxy potting material after the cover is inserted, a liquid-tight seal must be established between the cover and the body of the casing to prevent leakage of the potting material.
- the channel in the main casing is defined by a first and second member, 20, 22 extending in a direction parallel to one another and separated by a distance H forming the height of the channel.
- Cover 12 has a projection or lip 24 which extends into the channel and whose height is somewhat smaller than the distance H between members 20 and 22. It must be noted particularly that member 20 and 22 have a similar cross-section, both crosssections being sufficiently large to render the members rigid. With two such rigid members, a clearance must be left between cover and case, i.e.
- the distance H between the facing surfaces of members 20 and 22 must slightly exceed the height H 1 of the cover projection.
- the clearance must have a sufficient magnitude to compensate for tolerances in the size of the parts introduced by the molding process. It must further allow for variations in flatness of the mating surfaces of cover and case. These required clearances make a mechanical seal impossible.
- Fig. 4 the case has a first member 22 which is rigid as it was in the case illustrated in Figs. 1 and 2.
- the second member 20 is connected to member 22 at one extremity 24.
- the cross-sectional area of second member 20 decreases as the member extends from its first extremity 24 in a direction parallel to the first member to form a U-shaped channel.
- the decrease in cross-section causes the free end portion 25 of member 20 to be flexible.
- a lip 26 which projects from the cover and is to be inserted into the U-shaped channel has a first portion 27 with wedge-shaped cross-section and a second portion 28 with a rectangular cross-section.
- the cross-sectional area of wedge-shaped portion 27 decreases as it extends into the channel in the direction towards the bottom of the "U".
- the wedge shape is such that contact is maintained with rigid member 22 after contact with flexible member 20 is made.
- the flexibility of member 20 permits design interference between cover and case without creating undue stress in the member. Further, it causes a downward sealing force to be applied to projecting member 26, so that its bottom surface is tightly pressed against the top surface of member 22. A liquid-tight seal is thus formed.
- the legs of the U forming the channel extend in the horizontal direction.
- the U could also extend in a vertical direction, but gravity or some other force might in that case cause separation between the mating parts unless some external lock were added to the design.
- the channel forming members are a molded unit, as is the cover with its projecting member or lip.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- Housings And Mounting Of Transformers (AREA)
- Connector Housings Or Holding Contact Members (AREA)
Description
- The present invention relates to a transformer casing comprising a first casing part having an opening provided along its perifery with a first rigid member and a second member extending in a direction substantially parallel to said first rigid member at a predetermined distance therefrom and connected to said first rigid member at a first extremity thereof, said first and second member together forming a channel along the perifery of the opening having a substantially U-shaped cross section, and a second part having a shape substantially corresponding with that of the said opening and having along its perifery a projecting member adapted to be inserted into said channel.
- The standard two-part transformer casings now in use for high voltage transformers in the communications field consist of a main casing which has a groove or channel of rectangular cross-section into which the cover is slidably inserted. During manufacture, hot liquid potting material, e.g. epoxy, is poured into the case which is then subjected to a vacuum to remove entrapped air. In the past, leakage around the casing-cover seal occurred frequently during this process. To eliminate such leakage, sealers or adhesives were necessary which added to the cost of production.
- It is observed that US-A 4 273 406 shows a two part casing for a certain component in which the opening of the one part along its perifery is provided with portions having two rigid members forming a U-shaped channel there between and each of the portions being provided with a nose shaped projection extending at some distance from the casing body. The other casing part being provided with projecting members which can be inserted of the U-shaped channels on the other casing part and each projecting member having a nose portion which can cooperate with the nose portions on the other casing part sothat by turning the two casing parts with respect to each the two parts can coupled to each other. Such a locking arrangement does not provide a liquid tight seal between the two casing parts.
- It is an object of the present invention to provide a transformer casing in which a liquid-tight mechanical seal is achieved when one part is slid into the other, without use of any additional sealing material. It is a further object of the present invention to accomplish this end without departing from the material presently in use and without departing from the molding technique now used to manufacture both parts of the casing.
- In accordance with the invention the transformer casing is characterized in that the second member is flexible and said projecting member has a first portion clearing said flexible member and having a wedge-shaped cross section and a first surface for contacting said rigid member to form a first mechanical seal, said projecting member further having a second portion having a substantially rectangular cross section and a second surface for contacting said flexible member to form a back-up seal, wherein said first surface is at a second distance from said second surface which is at least equal to said predetermined distance and wherein said first and second part of said casing together constitute a housing containing hot potting compound. As a result of this construction, the flexible member exerts a sealing force onto the projecting member of the second part pressing it against the rigid member, thus creating a tight mechanical seal. In addition, a second or back-up seal is formed at the contact between the flexible member of the first part and the projecting member of the second part of the casing.
- In a preferred embodiment, the first part is molded as a single unit, the flexible member being a tapered beam having a substantially decreased cross section at the extremity contacting the projecting member of the second part.
- The present invention, as well as additional objects and advantages thereof, will be more fully appreciated from the following detailed description when considered in connection with the accompanying drawing in which:
-
- Fig. 1 is a cross-sectional view of a prior art mechanical joint between cover and case; and
- Fig. 2 is a cross-sectional view indicating problem areas for the mechanical joint shown in Fig. 1;
- Fig. 3 is an exploded view of a transformer casing and cover to be slidably inserted therein;
- Fig. 4 is a cross-sectional view of the mechanically sealing joint of the present invention.
- The transformer casing shown in an exploded view in Fig. 3 consists of a main casing (or first part) 10 and a cover (or second part) 12. The cover is to slide into the main body in the direction of the arrow. Since the body of the casing contains heated liquid epoxy potting material after the cover is inserted, a liquid-tight seal must be established between the cover and the body of the casing to prevent leakage of the potting material.
- Although transformers casings of the abovede- scribed type have been commercially available for approximately 6 years, sealers or adhesives were used during production because of potting compound leakage. The prior art mechanical seal illustrated in Figs. 1 and 2 illustrate the reason for such leakage. The channel in the main casing is defined by a first and second member, 20, 22 extending in a direction parallel to one another and separated by a distance H forming the height of the channel.
Cover 12 has a projection orlip 24 which extends into the channel and whose height is somewhat smaller than the distance H betweenmembers member members - A deliberate design interference to allow mechanical sealing would be impossible with this prior art transformer casing, since first, it would require very high force to slide the cover into the case and, secondly, a highly stressed corner would be created (see Fig. 2) which could easily result in breakage.
- The above-mentioned problem is avoided by the construction of the present invention as will be explained with reference to Fig. 4. In Fig. 4, the case has a
first member 22 which is rigid as it was in the case illustrated in Figs. 1 and 2. As previously, thesecond member 20 is connected tomember 22 at oneextremity 24. However, the cross-sectional area ofsecond member 20 decreases as the member extends from itsfirst extremity 24 in a direction parallel to the first member to form a U-shaped channel. The decrease in cross-section causes thefree end portion 25 ofmember 20 to be flexible. Additionally, alip 26 which projects from the cover and is to be inserted into the U-shaped channel has afirst portion 27 with wedge-shaped cross-section and asecond portion 28 with a rectangular cross-section. Specifically, the cross-sectional area of wedge-shaped portion 27 decreases as it extends into the channel in the direction towards the bottom of the "U". The wedge shape is such that contact is maintained withrigid member 22 after contact withflexible member 20 is made. The flexibility ofmember 20 permits design interference between cover and case without creating undue stress in the member. Further, it causes a downward sealing force to be applied to projectingmember 26, so that its bottom surface is tightly pressed against the top surface ofmember 22. A liquid-tight seal is thus formed. - If, contrary to expectation, liquid does escape through the seal formed by
members portion 28 oflip 26 andflexible end portion 25 ofmember 20. - The stress at the corners noted in the prior art joint can be further reduced by rounding the junction of the flexible member with the base of the U with a radius R. Similarly, the junction with the rigid member should be somewhat rounded to prevent stress concentration. Finally, somewhat rounded to prevent stress concentration. Finally, the maximum cross-section of the flexible member is maintained at the first extremity to absorb stress safely.
- In the preferred embodiment, the legs of the U forming the channel extend in the horizontal direction. The U could also extend in a vertical direction, but gravity or some other force might in that case cause separation between the mating parts unless some external lock were added to the design.
- In a preferred embodiment, just as in the prior art, the channel forming members are a molded unit, as is the cover with its projecting member or lip.
- A preferred embodiment may be described as follows:
- Material: PBT (20% glass) Celanese 3210
- Length of rigid member: 0,25 mm (.100 inch)
- Length of elastic member: 0,25 mm (.100 inch) (decreasing cross-section only)
- Distance between rigid and flexible member: 1,4/1,5 mm (.057/.060 inch)
- Maximum height of projecting portion of cover: 1,6 mm (.064 inch)
- Taper of projecting member: 6°
- Length of contact of projecting member and rigid member:
- 1,7 mm (.068 inch)
- Length of contact of projecting member and flexible member:
- 1 mm (.040 inch)
- It is seen that by means of the present invention, a liquid-tight mechanical seal can be achieved reliably, without requirement for additional parts or changes in the manufacturing process of a transformer and without use of additional sealing compounds.
- While the invention has been illustrated in a preferred embodiment, various modifications and changes in the structure and operation thereof will be evident to one skilled in the art and are intended to be encompassed in the following claims.
Claims (5)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US74648885A | 1985-06-19 | 1985-06-19 | |
US746488 | 1985-06-19 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0206406A1 EP0206406A1 (en) | 1986-12-30 |
EP0206406B1 true EP0206406B1 (en) | 1990-04-04 |
Family
ID=25001065
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19860201030 Expired EP0206406B1 (en) | 1985-06-19 | 1986-06-16 | Two-part transformer casing having liquid-tight seal |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0206406B1 (en) |
JP (2) | JPS6249608A (en) |
DE (1) | DE3670173D1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SE503874C2 (en) * | 1994-09-06 | 1996-09-23 | Vadsbo Interioer I Toereboda A | Housing for enclosing a transformer |
JP7375362B2 (en) * | 2019-08-09 | 2023-11-08 | 株式会社デンソー | ignition coil |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1543533A (en) * | 1920-06-25 | 1925-06-23 | Gen Electric | Incased electrical apparatus |
US2303435A (en) * | 1941-01-08 | 1942-12-01 | Westinghouse Electric & Mfg Co | Electrical apparatus |
US3150791A (en) * | 1961-11-02 | 1964-09-29 | Wendy D Shile | Lightweight collapsible shipping containers |
JPS51150630A (en) * | 1975-06-20 | 1976-12-24 | Matsushita Electric Ind Co Ltd | Electric equipment sealed container |
US4113098A (en) * | 1977-05-25 | 1978-09-12 | Howard Charles S | Pill-dispensing and storage container |
US4273406A (en) * | 1978-12-28 | 1981-06-16 | Mitsuoka Electric Mfg. Co., Ltd. | Electrical cord adapter |
-
1986
- 1986-06-16 EP EP19860201030 patent/EP0206406B1/en not_active Expired
- 1986-06-16 DE DE8686201030T patent/DE3670173D1/en not_active Expired - Lifetime
- 1986-06-17 JP JP13938286A patent/JPS6249608A/en active Pending
-
1994
- 1994-09-09 JP JP1126094U patent/JPH0744988U/en active Pending
Also Published As
Publication number | Publication date |
---|---|
EP0206406A1 (en) | 1986-12-30 |
DE3670173D1 (en) | 1990-05-10 |
JPS6249608A (en) | 1987-03-04 |
JPH0744988U (en) | 1995-12-05 |
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