US2878337A - Magnetic switches - Google Patents

Description

MAGNETIC SWITCHES Filed Oct. 14, 1957 2 Sheets-Sheet 1 FIG. I;

HARRY REIFEL IIVVENTOR BY W 3- M ATTORNEY March 17, 1959 H. REIFEL 2,878,337

MAGNETIC SWITCHES Filed Oct. 14, 1'95"! 2 Sheets-Sheet 2 FIG. 3

Zia 46 44 45 43 FIG 6 44 46 45 HARRY REIFEL INVENTOR FIG. 5 @YMJVW ATTORNEY United States Patent MAGNETIC SWITCHES Harry Reifel, Waltham, Mass.

Application October 14, 1957, Serial No. 689,792

2 Claims. (Cl. 20090) This invention relates to magnetic switches, and relates more particularly to magnetic relays capable of high speed operation.

In one embodiment of this invention, a reed of magnetizable metal is cantilever supported, and its free end overlaps a flattened extension of the pole piece of an electromagnet. The reed acts as a double-throw, singlepole switch, and carries a first contact which normally contacts a second contact for closing one circuit. When the electromagnet is energized, the free end of the reed is drawn towards the pole piece extension, causing the first and second contacts to be separated, and causing a third contact carried by the reed to contact a fourth contact for closing a second circuit. I

A feature of this invention is that bouncing of the reed is prevented by damping action of contacts. In one embodiment of this invention, this is accomplished by placing on'each contact side of the'reed, three small wires which are superimposedin an aligned row and cantilever supported. The free ends of the wires extend pasta contact wire on the reed which extends at a right angle to the three wires. The free ends of the three wires separate when spaced from their associated contact wire on the reed, and when the free end of the reed is moved towards the three wires, the associatd contact wire it carries touches the adjacent one of the three wires which then moves against the next adjacent one of the three wires which then moves against the other of the three wires, the resistance ofiered to this movement by the wires absorbing the shock of contact, and preventing bouncing of the reed.

Another feature of this invention resides in supporting a magnetic pole piece, a coil around the pole piece, and a shield can around the coil from one side of a cover for the shield can, and in supporting a block of electrical insulation from the other side of the shield can cover, with the block supporting a magnetic reed and its associated contacts.

An object of this invention is to restrain the bouncing of a contact closing reed of a magnetic switch.

Another object of this invention is to simplify and to reduce the cost of manufacture of high speed relays.

This invention will now be described with reference to the annexed drawings, of which:

Fig. 1 is a plan view of a relay embodying this invention;

Fig. 2 is a. side elevation of the relay;

Fig. 3 is a section along the line 33 of Fig. 1;

Fig. 4 is a view of one end of the relay, looking along the line 4--4 of Fig. 2;

Fig. 5 is an enlarged view of the contact wires on the reed of the relay, and of the cooperating contacts, and is taken along the line 55 of Fig. 3, and

Fig. 6 is a side view of the reed at its free end, and of the associated contact wires, and shows in an exaggerated manner how the free ends of the contact wires at one side of the reed are spaced apart when the reed and 'ice 2 the associated contact wire it carries is spaced from the free ends of the wires.

A cylindrical, metal, shield can 10 contains a spool 11 of electrical insulation on which is wound a coil 12. The can has a closed and an open end. A metal, cylindrical cover 13 having a closed end, has an open end fitted around the open end of the can 10, the inner diameter of the cylindrical portion of the cover 13 being the same as the outer diameter of the can. The cover 13 has extending centrally therethrough and attached thereto as by solder 14, one end of a pole piece 15 of the coil 12, which pole piece extends through the open center of the spool 11 when the cover is in position on the open end of the can 10. The pole piece 15 has a particylindrical extension 16 which extends from the cover 13, the pole piece and its extension extending from opposite sides of the closed end of the cover. The pole piece extension 16 has a flattened upper surface.

The coil 12 has ends attached to terminal pins 17 around which extends insulators 18 which are fitted in openings in the closed end of the cover 13.

The closed end of the cover 13 has extending therethrough and secured thereto as by solder 20, the inner ends of four metal straps 21 which extend outwardly from the side of the closed end of the cover 13 that the pole piece extension extends from. The outer ends of the straps 21 are secured by screws 22 and nuts 23 to a block 24 of electrical insulation which has an inner end spaced from the closed end of the can cover 13.

The block 24 has a longitudinally extending, rectangular-shaped passage 25 therethrough, within which extends a reed 26 of magnetic spring metal which has a wide outer portion 27 attached by screws 28 and nuts 29 to reduced thickness portions of the block 24 which are formed by cutting away upper end portions of the block on opposite sides of a central upper portion of the block at its outer end. The outer portion 27 of the reed has electrical terminal extensions 30 which extend outwardly from the screws 28.

Extending within the passage 25 above and below the reed 26 are contact supporting arms 32 of spring metal which are secured to the block 24 by bolts 34 and nuts 36. The outer ends of the arms 32 are formed as electrical terminals 38. The inner portions of the arms 32 are curved inwardly towards the reed 26 and have flattened inner ends which have attached to the inner sides thereof contact supporting strips 40 of spring metal. To the inner surface of each of the strips 40 is attached as by spot welding, the outer end of a wire 43. The outer end of a similar wire 44 is attached as by spot welding to the outer end of the wire 43. The outer end of a similar wire 45 is attached as by spot welding to the outer end of the wire 44. The wires 43, 44 and 45 are superimposed in an aligned row as shown by Figs. 3, 5 and 6 of the drawings. Each side of the reed 26 has attached thereto as by spot welding, a metal wire 46, the axis of which extends at a right angle to the plane containing the axes of the wires 43, 44 and 45.

Attached to the upper and lower sides of the block 24 by the bolts 34 and nuts 36 are straps 48 of spring metal which have slotted inner ends through which extend screws 49 which are threaded into the block 24, and the inner ends of which contact the flattened inner end portions of the arms 32. The screws 49 can be adjusted to vary the position of each set of contact wires 4345 relative to the adjacent wire 46 on the reed 26.

The reed 26 is substantially axially aligned with the pole piece 15, and its inner end extends over the flattened surface of the pole piece extension 16. Normally, when the coil 12 is not energized, the inner end of the reed is spaced from the extension 16, the upper contact wire 45 is in contact with the upper contact wire 46,

and the lower contact wire 45 is spaced from the lower contact wire 46 as shown, by Figs. 3 and 5.

When the coil 12 is energized by flowing direct current through it, the pole piece extension 16 attracts the free, inner end of the reed 26 towards it, causing the upper contact wire 46 on the reed to move away from the upper contact wire 45, and causing the lower contact wire 46 on the reed to move against the lower contact wire 45. When the current flow through the coil is discontinued, the reed 26 returns to its normal position with its upper contact wire 46 in contact with the upper contact wire 45. The relay thus acts as a single-pole, double-throw switch.

The inner ends of the contact wires of each set of wires 43--45 separate as is shown in exaggerated fashion by Fig. 6 when the adjacent contact wire 46 on the reed is spaced from a wire 45, this resulting from the wires 4345 being cantilever supported at their outer ends, their inner, free ends being free to move apart. The wires 4345 may be bent somewhat as shown by Fig. 6 so that when pressure against their ends is removed, their resiliency will cause them to resume their bent positions.

When a contact wire 46 on the reed moves against a wire 45, the latter moves against an adjacent wire 44 which moves against an adjacent wire 43 which moves against an adjacent strip 40 which is deflected outwardly as the reed continues to move towards it. Thus, the shock resulting from a contact wire 46 on the reed striking an adjacent contact wire 45 is absorbed by the flexure of the adjacent wires 4345 and the adjacent strip 40 so that the usual bouncing and resulting erratic switch closing is eliminated or greatly reduced.

In assembling the relay, the pole piece and the supporting straps 21 of the block 24 are attached to the can cover 13. The block 24 with its contact mechanism is attached to the straps 21. The spool 11 with the coil 12 therearound is placed on the pole piece 15 and the ends of the coil are connected to the terminal pins 17. The shield can 10 is then placed around the spool and coil with its open end within the open end of the can cover 13. Solder is then applied at around the open end of the cover 13 and to the adjacent outer surface of the can 10, hermetically sealing the coil 12 within the can 10.

What is claimed is:

1. A magnetic switch comprising a cylindrical, metal, coil-shield can having an open end and a closed end, a metal cover for said open end of said can, a magnetic pole piece attached to said cover and eXtending from one side of the center thereof into said can along the axis thereof, a magnetic coil within said can around said pole piece, said pole piece having an extension with a fiat portion extending from the other side of said cover, a plurality of metal straps attached to said cover and extending from said other side thereof, a block of electrical insulation attached to said straps, said block having a passage therethrough aligned with said pole piece, a reed of magnetic spring metal extending within said passage and cantilever supported from said block, the free end of said reed extending over said flat portion of said pole piece extension, said coil when energized by the flow of current therethrough, magnetizing said pole piece and causing said free end of said reed to be moved towards said extension, first contact means on said reed adjacent said free end, and second con tact means arranged to be contacted by said first contact means when said free end of said reed is moved towards said extension.

2. A magnetic switch as claimed in claim 1 in which said pole piece is cylindrical, and in which said extension is parti-cylindrical.

References Cited in the file of this patent UNITED STATES PATENTS 1,769,279 True July 1, 1930 2,497,547 Hastings Feb. 14, 1950 2,758,173 Riley Aug. 7, 1956

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