US3047692A - Combination sensitive and power relay - Google Patents

Description

July 31, 1962 A. G. THOMAS COMBINATION SENSITIVE AND POWER RELAY Filed Dec. 8, 1958 IN V EN TOR.

United States Patent 3,047,692 COMBINATION SENSITiVE AND POWER RELAY Albert G. Thomas, 1711 Galloway Drive, Charlottesville, Va. Filed Dec. 8, 1958, Ser. No. 778,867 9 Claims. (Cl. 200-97) This invention relates to improved relays. In using relays in circuits of broad variety it is often necessary to supply feeble current to a sensitive relay and to connect the sensitive relay to control a power relay which can handle heavy current. This practice has some undesirable features however, since two relays are used, resulting in increased expense, more complicated circuitry, more required space, less reliability and slower An additional j is to P a Combination sellsithe relay is closed, the attracted plunger 33 will stretch tive and power relay which occupies relatively small space.

A further object is to provide a combination sensitive and power relay of rugged design and which may be readily adjusted for reliable operation.

Another object is to provide a relay with various features as described.

Other objects will be evident in the following description.

The drawing represents a side elevation, in part section, of a relay having a number of novel features.

In the drawing, relay arm 27 is pivotally supported by upright 28 at 29 which may be a pin, screw, or knife edge arrangement or any suitable support. Stop member 30 attached to upright 28 limits rotation of arm or armature 27 about the pivot in clockwise direction. Arm 27 is extended to provide short arm 31 to which tension spring 32 is attached, the other end of the spring being attached to plunger 33 of solenoid 34 fastened to relay base 35. Upright or leg 28, magnet or solenoid'36, and electrically conductive leg 37 are also attached to base 35 which is of plastic or other electrically insulating material. The core 38 of magnet 36 may be laminated and this core may have a recessed upper end, as shown in section, so that iron plunger 39 may be drawn into thecore. This construction has the advantage that there is a more or less constant air gap and strong magnetic forces are applied to the relay armature in its initial or normal position. In the usual type of relay the armature is, initially, at relatively great distance from the attracting magnet. The construction of my relay will therefore provide fast movement of the armature when the magnetizing winding 36 is energized. If desired, the magnetic core 38 can be extended as core 39 imbedded in the base and this can be brought into contact with leg 28 which may be of magnetic iron, as may the arm 27. This construction provides a closed magnetic circuit to a large extent and increases the magnetic force on the relay armature.

Windings 34 and 36 are connected in parallel, or in series as desired, and they may be simultaneously energized by current supplied by conductors 40 in the controlling circuit. Weight or mass 41 is attached to one end of compression spring 42 the other end of which is fastened to arm 27 which carries electrical contact 43. Metallic or other conductive disc 44 has -a center hole through which the shank of button 45 is passed. This disc is freely rotatable around the shank of this button which is yieldingly supported by attached spring 46 fastened to metal or other conductive leg 37. Conductor 48 is yieldingly connected to arm 27 and conductor 47 is connected to leg 37, for connecting the relay into circuit. Stop arm 49 is fastened to solenoid 34 and normally holds plunger 33 in the position shown, under light tension from spring 32. Relay contact 50 is attached to metal arm 51 extending from leg 37. This contact is adjacent the under surface of disc 44 which may be of silver, silver alloy, or other suitable electrically conductive material. This disc, or the contacts, or both, could be of graphite or graphitic substance.

'In operation, when conductors 40 are energized, element 39 is pulled down into element 38 by magnetic force and plunger 33 is similarly pulled down into solenoid 34, resulting in the stretching of spring 32 to provide increased tension. between plunger 33 and the surrounding core tube of solenoid 34 be sufficiently close that the escaping air will act as a brake to retard the full travel of plunger 33, until plunger 39 has completed its downward travel. In this way the relay closes with spring 32 in low-tension condition so that the relay will be sensitive, but when spring 32 to provide greater tension for moving arm 27 rapidly to break the relay circuit including the contacts, when coils 34 and 36 are deenergized. A further advantage is that a greater force is available to prevent i the contacts from sticking. When the relay is once closed the holding force is great enough to take care of the increased spring tension. The pneumatic resistance to the movement of plunger 33 will temporarily hold spring 32 in stretched condition.

When arm 27 is suddenly stopped, the weight 41 tends to continue moving and so to compress spring 42 to prevent contact bounce. This spring may be frictionally mounted to be aperiodic or liquid damping may be used by placing mercury or other liquid in a chamber in arm 27 and providing a restricted orifice to resist flow of the liquid. The element 41 may be omitted, as well as the liquid. Element 39 could also be omitted if desired.

When the arm 27 is pulled down, contact 43 is pressed against disc 44 which is pressed against contact 50 to close the relay circuit including conductors 47 and 48.

The spring 46 will yield sufficiently for disc 44 to be properly aligned between the contacts. Since the disc 44 is freely rotatable it will creep around under action of the opening and closing contacts so that a fresh contact surface will be provided for both elements 43 and 50. Furthermore, with two contact combinations, there will be less danger of the contacts sticking.

It will be seen that this relay is, in essence, a combination sensitive and power relay. Spring 32 can be made quite weak normally so that it is just strong enough to hold the contacts apart, for a normally open relay or to hold the contacts closed for a normally closed relay. Therefore a very weak current through the main relay winding will cause movement of the relay arm which can, of course, be approximately balanced about its pivot if desired.

ly moves arm 27 to separate the contacts before the slower moving plunger 33 shifts to reduce the tension in It is desirable that the air gap spring 32, thereby changing the relay, in effect, to a sensitive relay again.

It is obvious therefore that this relay serves both as a sensitive relay, actuated by relatively feeble currents, and also as a power relay which can control relatively heavy currents. The temporary increased tension of the spring 32 is particularly valuable in preventing sticking of the relay contacts which often happens in relays of prior design.

What I claim is:

1. In a relay, a pair of relatively movable contacts, an armature for moving at least one of said contacts, a magnetizing winding for causing movement of said armature, resilient means for moving said armature in one direction, and means including a magnetizing winding for increasing stress of said resilient means when said second named magnetizing winding is energized.

2. In a relay, a pair of relatively movable contacts, an arm for moving at least one of said contacts, a magnetizing winding for causing movement of said arm, resilient means for moving said arm in one sense, a'solenoid plunger connected with said resilient means, and a solenoid winding for magnetizing said plunger to cause movement thereof to stress said resilient means.

3. The relay as described in claim 2, said magnetizing Winding and said solenoid winding being electrically connected.

4. The relay as described in claim 2, said magnetizing winding causing movement of said arm in one sense and said solenoid Winding causing movement of said arm in opposite sense.

5. The relay as described in claim 2, said solenoid plunger being smaller in diameter than the solenoid tube surrounding said plunger, in order to allow escape of air around said plunger.

6. The relay as described in claim 2, said solenoid plunger when magnetized stressing said resilient means to urge said arm in opposite sense to that caused by said magnetizing Winding, said plunger being moved through its full travel after a time delay after movement of said arm through its full travel.

7. In a relay, a pair of relatively movable contacts, an arm for moving at least one of said contacts, a magnetizing winding for causing movement of said arm, re-

4- silient means for moving said arm in one sense, magnetizable means operatively connected with said resilient means, and winding means electrically connected with said magnetizing winding, said winding means causing movement of said m'agnetizable means to stress Said resilient means when said winding means is energized.

8. The relay as described in claim 7, said magnetizable means moving through its full travel only after full contact-closing travel of said arm occurs.

9. In a relay, a pair of relatively movable contacts, means attached to at least one of said contacts to produce movement thereof, means including a magnetizing windingfor producing said movement, resilient means for causing relative movement of said contacts in opposite sense to the relative movement caused by said magnetizinig winding, and means including another magnetizing winding for increasing stress of said resilient means when said other magnetizing winding is energized.

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