DE2126399A1 - AC capacitor - Google Patents

Description

E. 331.

Appendix to

Getoauhmnuctorhilf _S

RO BERT BOSC II G Ii B H, 7 Stuttgart ( Germany)

Change lS voltage capacitor

The invention has an AC capacitor Plastic bands on metallized 'self-healing coverings and built-in switch to the subject with a tear-off wire, which reduces the capacitor current with increasing mechanical and / or electrical stress interrupts.

Wire breakers with a predetermined breaking point for self-healing are known AC capacitors with paper dielectric If such capacitors burn, they develop gases,

- 2 209851/0214

Robert Bosch GMBH . R. 331 Ba / Kf

Stuttgart

which lead to a pressure increase in the capacitor housing, see above that the housing is deformed in the axial direction and the switch responds.

For AC capacitors with a plastic dielectric the development of smoldering gas occurs at a significantly higher temperature than with capacitors with paper as the dielectric and runs with rapidly increasing steepness, which is an explosive one Destruction of the capacitors.

In the case of some plastics, there is also greater gas evolution instead of a strong and dangerous rise in current that causes a fuse to respond.

It should also be taken into account that, depending on the plastic used and the pretreatment, plastic capacitors "shrink more or less in the axial direction when heated, which can result in the possible extension of the housing being insufficient to switch off the capacitor with the known Uiekelfixierung by Uickel retaining washers AC voltage capacitors with plastic dielectric effective disconnector ¹ must therefore respond to mechanical and electrical stress and be installed in such a way that it responds as quickly as possible with sufficient resistance to shaking and thermal shock resistance.

A circuit breaker which fulfills these conditions contains, according to the invention, a hard-drawn breakaway and fusible wire with a diameter of 0.15-0.3 mm and with an elongation at break of preferably 3-5 ° / ° suf 10 mm gauge length between a contact bridge on an end face of a capacitor element fixed in a capacitor housing and a Kontier: sator connection is clamped.

209851 / 02U ~ ³ ~

Robert Bosch GmbH E. 331 Ba / Kf

"Stuttgart

The tensioned breakaway and fuse wire can be made of silver or silver-plated or silver-plated Copper and must be at least 10 mm long.

In the drawing, a fluorescent tube capacitor for a nominal voltage is shown as an exemplary embodiment of the subject matter of the invention of 220 volts with a capacity of 10yuF on average shown.

A capacitor winding 11 is built into a housing 10 made of aluminum and is made of polypropylene foils coated with aluminum is wound on a Vickel sleeve 12. For secure fixation of the winding 11 are two seated on the ends of the winding tube 12 Centering caps 13, 14 with pipe sockets 13 ', 14' glass fiber reinforced polyamide, which engage on both sides in the winding sleeves 12, while the outer edges the centering caps 13, 14 on the inner wall of the housing 10 fed up issue.

A stretching bead provided above the upper centering cap serves to further fix the capacitor winding 11 in the housing 15, which connects the capacitor winding with the one on the winding tube 12 seated centering caps 13j, 14 in the axial direction in the housing 10.

The capacitor case 10 eats through a plastic cover with connecting tongues 17, 18 en hollow rivets 19 completed, the on a retaining bead 21 located above the stretch bead 15 in the Housing 10 is seated and through the bent edge of the housing pressed into a rubber ring 22 in a groove in the cover 16 10 is recorded.

To connect the capacitor winding 11 over two on his Contact bridges 23 and 24 sprayed onto the end faces are used

209851 / 02U

• ■ ' Tv \. * 4. - 4 -

Robert Bosch GmbH E. 331 Ea / Kf

Stuttgart

on the one hand an insulated connecting wire 25, one end of which is welded to the lower contact bridge 24 and of which the other end is soldered into the hollow rivet 20 in the cover 16.

A breakaway and fusible wire 26 made of silver with a diameter of 0.2 mm is welded to the contact bridge 23 located at the top of the capacitor. Since the distance from the bridge 23 to the second hollow rivet 19 with the terminal lug 17 is too small, the wire 26 from the bridge 23 is first passed over the winding sleeve 12 and down along it and then over a bead 27 nm at the end of the pipe socket I3 the centering cap 13 with an incision 27 stretched taut to the still free hollow rivet 19 with the second terminal lug I ?. In addition to distancing the wire 26, the bead 27 also has the task of preventing the wire from cutting into before it is torn off at a higher temperature.

In this embodiment, the tear-off and fuse wire between contact bridge 23 and connection 17, 19 has a length of about 24 mm.

This length is short enough to allow the wire 26 to be torn off, for example by shrinking the polypropylene winding 11 between the winding bridge 23 and the bead 27 on the tube attachment I3 ^{1 of} the centering cap 13. The wire 26 is also torn off if any smoldering gases that have arisen from the roll 11 pass through openings 13 ″ and through recesses 25 and impressions 26 in the centering cap 13 into the space above the centering cap 13, and with increasing pressure on the cover 16 expand the stretching bead 15 and thereby tear off the wire 26 between the connection 17 and the bead 27. On the other hand, the wire 26 can also be melted by braising in the leg 11 and thus increasing the capacitor current and the capacitor is thereby switched off.

- 5 - '"5209-8S1702U

Claims (9)

Robert Bosch GmbH R. 351 Ba / Kf Stuttgart Expectations lJ AC voltage capacitor with self-healing coatings vapor-deposited on plastic strips and built-in switch with a breakaway wire that interrupts the capacitor current when the mechanical and / or electrical stress increases, characterized by a hard-drawn breakaway and fuse wire with a diameter of 0.15 - J 0.3 mm and an elongation at break of 3 - 5 ° / ° on 10 mm measuring length, which is clamped between a contact bridge on an end face of a capacitor element fixed in a housing and a capacitor connection. 2. Capacitor according to claim 1, characterized in that the tear-off and fuse wire consists of silver. 3. Capacitor according to claim 1, characterized in that the tear-off and fuse wire made of silver-plated or silver " plated copper. 4. Capacitor according to claim 1 to 3? characterized, that the tear-off and fuse wire has a free length of at least 10 mm. 5. Capacitor according to claim 1 to 4, in particular a wound capacitor with a cylindrical housing, characterized in that 2 0 9851 / 02U ^ - 6 - Robert Bosch GmbH R. 551 Ba / Kf Stuttgart the winding is wound onto a cylindrical winding tube and by two resting on the ends of the winding tube 0-2) Centering caps made of plastic on both sides of the roll with tube sockets protruding into the roll core centered in the housing and through at least one winding bead in the housing wall through the centering caps and the winding tube is fixed in the axial direction. 6. Capacitor according to claim 4, characterized in that the centering caps are made of glass fiber reinforced with a polyamide and are provided with recesses and impressions that allow the passage of stewing gases to the cover side of the Allow capacitors. 7. Capacitor according to claim 4 and 5, characterized in that that the tear-off wire passed through the pipe socket of a centering cap and extended to the required minimum is. 8. Capacitor according to claim 6, characterized in that the pipe attachment at the point of passage of the tear-off wire is reinforced inwards by a bead. - 7th 209851 / 02U Robert Bosch GmbH R. 33I Ba / Kf Stuttgart 9. Capacitor according to claim 8, characterized in that the bead is provided with an incision through which the Tear-off wire is guided. 10 »capacitor according to claim 9i, characterized in that (| the tear-off wire is clamped in the incision. 09851/0214 Blank page