US2382995A - Shock-responsive latching device - Google Patents

Description

Aug. 21, 1945. R B. IMMEL ET AL. 2,382,995

SHOCK RESPONSIVE LATCHING DEVICE Filed Nov. 24, 1945 2 Shets-Sheet 1 [MUM/an WITNESSES: INVENTORS Z v 6040/? afmnve/ and 7 FFa k .f/amar. M'w BY v IZWKZ.

ATTORNEY tactors of the just-mentioned type.

Patented Aug. 21, 1945 UNITED 1 STATES PATENT OFFICE s'HocK-nEsroNsIvE LATCHING DEVICE Ralph B. Immel, Wilkinsbur'g, Pa., and Frank Slamar, Annapolis, Md., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 24, 1943, Serial No. 511,564

3 Claims. (01. 74-527) No. $8,388, filed September 15, 1942, on a Latch for contactors, the magnetic core structure of a relay-type contact-or is provided with a latch and has also a vibratory weight which is pivoted on and elastically braced against the core structure and oscillates upon the occurrence of shock thereby moving the latch into engagement with the armature of the contactor to secure the armature in the position which the armature assumed previous to the shock.

It is a general object of our invention to improve latchin devices and shock-protected con- More specifically, it is among the objects to increase the efficacy and reliability of such devices, and also to facilitate the manufacture and assembly of this type apparatus. We are also aiming at providing a latching device which lends itself -more readily than the known constructions to bein applied in relays, switches andother apparatus of widely difierent design and purpose.

According to the invention, in one of its aspects, the latching device is arranged near the contacts of a contactor and particularly between two spaced sets of contacts actuated by a rocking armature so that the latch lies close to the path or periphery of contact motion. The latching device proper, including a movable latch member and a shock or vibration responsive oscillatory system, is provided with a'sup-port or frame structure separate from that of the apparatus to be protected so as to form a structurally and operatively separate unit.

These and other objects and features of the invention will be understood from the following description of the embodiment of a shock-proof contactor shown in the drawings.

Fig. lis a front view of the complete contactor; V

Fig. 2 is a side elevation of the same contactor;

Fig. 3 is a part-sectional side elevation, the sectional part extending along the plane indicated in Fig. 1 by the dash-and-dot" line marked III III;

Fig. 4 shows thelatching device proper and mainly in a section through the symmetry axis of Fig. 1, the device being illustrated in condition corresponding to that shown in Fig. 3;

Fig. 5 represents the latching device by a sectional view similar to that of Fig. 4, but with the latch moved into operative position;

Fig. 6 is a view of the latching device proper taken from the bottom side of Fig. 4, and

Fig. '7 is a view, similar to'Figs. 4 and 5, of a somewhat modified form of the latching device.

Referring to Figs. 1, 2, and 3, the illustrated contactor has a magnetic structure I which carries a magnet core 2 and a coil 3 placed around the core. An abutment member 4 is mountedon the magnetic structure I and has a portion 5 which extends towards the area in front of the magnet core. The abutment member 4 and the adjacent end of the structure I form a corner at 6 which serves a dihedral pivot bearing for the armature 1. The armature'is beveled so as to form a. knife-type edge which engages the pivot hearing. A weight 8 is firmly secured to the armature I, and so is a bracket 9 which forms an abutment for a coiled compression spring whose other end is braced against an abutment formed by the portion 5 of the member 4. A locking member 20 is also rigidly secured to thearmature for a purpose to be described hereinafter.

Two contact members H are mounted on an insulating carrier ll secured to the armature 'l and are each connected by a flexible cable [2 with two respective terminals l3. Each contact I l cooperates with one of two stationary contacts M which are provided with terminalsl5 respectively. Blowout coils it serve to quench the interrupting arcs occurring between each' pair of contacts II and Mduring the interrupting operation. nals 15, the blowout coils i6, and the'terminals E3 of the movable'contact H are mounted on a common base I! of molded insulating material which is firmly secured to the magnetic structure I. The base I1 has a recess or groove it in its center portion and a ridge !9 which traverses the recess in order to increase the mechanical strength of the molded body. I

The armature assembly, including the armature proper and the elements 9, 20, I l and II attached thereto is so biased by the spring it that the pivot edge of the armature 'l is held against the dihedral pivot bearing at 6. In this manner, the armature assembly is constrained to perform angular movements about the axis of the pivot bearing towards and away from the magnet core. The force of spring I!) has also a component whic biases the armature assembly away from the magnet core and towards a stationary stop formed at? (Fig. 3) by the portion 5 of the abutment The stationary contacts l4, their termi member 4. When the armature abuts against the stop, the movable contacts H are separated from the stationary contacts I4 (Fig. 2) so that the circuit between each pair of terminals I3 and I5 is opened. When the relay coil,3 is energized, the armature is attracted by the magnet core 2 and more: its smut "H into circuit "closing position.

In order to prevent the above described contactor from performing undesired operations when subjected to shock and vibratiomespecially as occurring on naval vessels due to the operation of their internal equipment or by contact with external objects, a latchinzdevice .is provided. This latching device includes a substantially U-shaped support or frame structure 2 |,consisting, for instance, of a sturdy metal casting, whose base portion 22 is fastened by screws 22' to the insulating base I1 and the magnetic structure I or the contactor (Fig. 3).

Referring now to Elgs. 4, 5 and 6, 'a channelshaped latching lever 23 has its flange portions 24 fulcrumed about a pin 26 which is riveted to the two parallel legs of the U-shaped support 2| and located relatively close to the base portion 22 i of the structure. Another pin 21 riveted to the legs of the support 2| at a place relatively remote from the base portion 22has a projection'23 which serves as an abutment or holder for a wire spring 28. presses against the latching lever 23 so as to bias it toward its inoperative position illustrated in Fllgs. 1, 3 and 4. The lever 23 has an opening at for engagement with the latch 20 of the armature 1 (Fig. 3) when the armature is in contact closing position.

A third pin 30 extending in parallel to pins '26 and 21 between the two legs of the U-shaped support 2| and likewise fastened thereto by riveting, serves as a pivot for a weight 3| which has cams 32 and 33 facing the latching lever 23. The cam 33 is part of a screw 34 which permits adjusting the cam as regards its distance from the main body of the weight 3|. A strand-shaped spring 33 is at one end firmly secured to the weight 3| and has its other end extending through an opening in an extension 36 of the latching lever 23. The spring tends to hold the weight 3| in the position shown in Fig. 4, while permitting it to perform oscillatory motions about the pin 30 when subjected to shock or vibration. In other words, the Weight 3| and the spring 35 represent an 05- cillatory mechanical system capable of damped vibrations.

When the contactor is exposed to shock or vi- L bration, the weight 3| will perform oscillatory motions previous to any appreciable motion performed by the armature assembly of the relay due to the fact that the mass and elasticity of the oscillatory latching system are dimensioned for a considerably smaller time constant than the relatively heavy mass and relatively stiff spring of the armature assembly. As soon as such oscillations of the latching system occur, the weight 3| will move its cams 32 and 33 towards and away from the latching lever 23. When cam 33 moves against the latching lever, it turns the lever against the force of spring 28 into latching position. The cam 32 when moving against the lever 23 has the same effect. Consequently, both cams cooperate during a sequence of Oscillations of weight 3| to render the latching lever operative.

Fig. 5 represents a stage of vibratory operation in which theprojection 33 has moved towards the lever 23. The same figure illustrates, by a broken This spring is wound around the pin 26 and line, a phase of the same vibratory motion in which the cam 32 engages the lever 23. It will be noted that the distance of projection 32 from the axis of oscillation is shorter than that of the cam 33. The difference is so dimensioned that the torque imparted to lever 23 by either cam is approximately equal to that produced by the other cam.

Referring to the operation represented by Fig. 5, and assuming that the relay was in the inoperative position shown in Figs. 2 and 3 before the occurrence of a shock, it will be apparent that, since the lever 23 remains in the path of motion of latch 20 as long as the shock is effective, the armature assembly cannot move towards the contact closing position because the latch 20 would abut against the free end of the latching lever 23,

as is illustrated in full line in Fig. 5.

Assuming now that the contactor was in circuit closing position before the occurrence of a shock, the operation of the latching lever 23 as elucidated by Fig. 5 will cause the opening 25 of the lever to pass over the end of latch 20, as is shown in Fig. 5 by a dash line representation of the latch. Consequently, the contactor is now prevented from performing unintentional opening movements as long as the vibratory function of the oscillatory system persists. In the modified embodiment shown in Fig. 7, the latching lever 24 and its opening 25' are shaped differently from the corresponding items of the above-described embodiment, the pin 21 serving as a stop for limiting the motion of the lever towards the armature latch 20. Otherwise the design is similar to that of the device previously described as will be apparent from the corresponding reference numerals.

It is essential for the above described device that the latching mechanism is located at the periphery of the armature close to the contacts operated by the armature. In this location of the latching device, a most eifective blocking of the armature and contact assembly in either its opening or closing position is obtained. It is also important that the latching device has its own support and forms an operative unit capable of operation independent of the contactor or other device to be protected, with the only exception that some latch-like element 20 is to be provided at the apparatus to be protected, such latch, however, being easily applicable or supplemented to almost any type of apparatus of interest. The provision of a separate latching unit has the advantage that it may be added to different contactors and other apparatus to be protected from faulty operation under shock or vibration. Such a separate latching unit offers the further advantage of facilitating the manufacture because it can be completed and tested separate from the apparatus to be shock-proofed and permits also an easy exchange of a latching unit in case of repairs.

Being aware of the fact that the apparatus and latching devices as described in the foregoing may be modified in various respects without departing from the gist and scope of our invention, we wish this description to be understood as illustrative and not in a limiting sense.

We claim as our invention:

1. A shock-responsive device for latching a contactor, comprising in combination a support; a latch lever having one end pivoted to said support for limited angular motion and being normally biased toward inoperative position, a me-- chanical oscillatory device having an unbalance weight pivoted to said support to perform oscillatory pivotal motion under shock, an adjusting screw passing through said weight so as to be engageable at one end with said lever and accessible at the side of said weight away from said lever for adjusting the lever-engaging end relative to said weight, a cam member disposed on said weight at a placeradially opposite to said screw with respect to the pivot axis of said weight and arranged for engaging said lever so that said screw and said cam member move said lever alternately into latching position during the occurrence of shock.

2. A shock-responsive device for latching a con' tactor, comprising in combination a support having a base portion and two leg portions extending substantially at right angles to said base portion, a pivot disposed between said legs near said base portion, a spring biased latching lever fulcrumed on said pivot and extending away from said base portion between said leg portions, another pivot disposed between said leg portions away from said base portion, a mechanical vibra' tory system having a weight mounted on said other pivot and two cam members disposed on said weight at opposite sides of said other pivot and projecting toward said lever for alternately moving said latching lever against its bias into latching position upon the occurrence of oscillatory pivotal motion of said w'eight due to shock, one of said cam members being adjustable relative .to said weight.

3. A shock-responsive latching device, comprising in combination a substantially U-shaped support having a base portion designed for attachment to an apparatus to be latched and two leg portions extending in parallel to each other, a pin secured between said leg portions near and in parallel to said base, a spring biased latching lever pivoted on said pin and extending away from said base, another pin secured between said leg portions away from said base portion, and a mechanical vibratory system having a weight mounted on said other pin, and two cam members disposed on said weight at opposite sides of said other pin and directed toward said lever for alternately moving said lever against its bias into latching position upon the occurrence of oscillatory pivotal motion of said weight due to shock, one of said cam members. having an adjusting screw for adjusting its position relative to said weight.

RALPH B. IMMEL. FRANK SLAMAR.

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