US1497089A - Electric switch - Google Patents

Description

June 1% 1924.,

J. A. CRABTREE ELECTRIC SWITCH Filed Dec- 16 1919 3 Sheets-Sheet 1 June 10 192%e 1,497J089 J. A. CRABTREE ELECTRIC SWITCH Filed Dec. 15 1919 3 Sheets-Sheet 2 June 16 {1924.

J. A. CRABTREE ELECTRIC SWITCH Filed Dec. 16 1919 3- Sheets-Sheet 3 Patented is re, 1924.

%T TT JOHN ASHWORTH. CRABTBEE, F YARDLEY, La

ELECTRIC SWITCH.

Application filed December 16, 1919. Serial No. 845,228.

To all whom it may concern:

Be it known that I, J oHiw ASHWORTH CRABTREE, a subject of the Kingdom of Great Britain, residing at Lynwood,

Clements Road, Yardley, in the county of \Varwick, England, engineer, have invented certain new and useful Improvements in or Relating to Electric Switches, of which the following is a specification.

This invention comprises certain improvements in or relating to electric switches, of the type involving a pivoted operating member, a pivoted contact arm or member, and a spring element operating between said members adapted to enable the contact member to have a quick make or break action.

In the type of switch to which this invention refers, the spring element is coupled pivotally to the operating member and contact member at positions eccentrically of their respective axes, both extremities of the spring element being adapted to move in the action of closing or opening the switch. The present invention refers primarily to the stop provision utilized for limiting the movements of the switch both in its closing and opening operations, and the present invention has for its pur ose to provide stop provision which is particularly Simple, effectual, and rigid. According to the present invention, in this type of switch the contact arm or member is adapted to engage with stop provision by an upward movement of the part of said contact arm or member which comes into contact with said stop provision. By upward movement is meant movement in a direction away from the rear face of the switch base; this being provided, the movement may occur at any angle. Advantageously the pivoted operating member above referred to is pivoted in the bridge, and the said bridge itself constitutes the stop provision.

The present invention further refers primarily to the provision incorporated in this type of switch for initially actuating the contact member positively. According to the resent invention, this function is fulfilled throughthe medium of the spring eleelement may be adapted to function as a lever. In one arrangement the spring element is adapted to engage intermediately to its axes with a fulcrum portion, causing the ment. In fulfilling this function the spring said spring element to be rocked about said fulcrum to positively actuate the contact member. In this invention the expression sprrng elementiis intended to include any provision Involving a s ring, which prov1s1on is coupled pivotal y on the one hand to the operating member and on the other hand to the contact member. The spring itself may come into contact with the fulcrum portion, but I refer that a part other than the spring itself should experience this engagement. To this end, in a case in which the spring element constitutes a telescopic sprin link a part of the telescopic mechanism is advantageously extended to intervene between the spring and the fulcrum portion. Or I may incorporate be- .tween the two axes of the spring element a link or medium which is independent of the spring, but which fulfils the function of initially actuating the contact, member positively.

The present invention has further for its purpose to more effectively, securely and durably secure the pivot in the said bridge, and according to the present invention the pivot is retained by the screws utilized for fastening the bridge.

The present invention also refers to the porcelain or other base upon which the switch mechanism is mounted. Usually a 5 base of this character is secured to any appropriate supporting part by screws which pass through perforations in the base. It is the object of the present invention to reduce the dimensions of this type of base, other considerations remaining the same. reduction in the overall dimensions of such a base has a number of advantages. One advantage is that when a number of the switches are mounted in proximity to each as other they can be arranged in much more compact formation. The invention has further the advantage that the possibility of breakage of the china base is substantially reduced. me

With this object in View I adapt the base to be secured by screws or fastening members located externally of the perimeter of the base. The said screws or fastenin members retain the base through the medium of mg a metal part or parts which is or are anchored to the base by the fastening screws or members utilized for securing the bridge,

or the said parts may be integral with the bridge.

In order that this invention may be clearly understood and readily carried into practice, reference may be had to the appended explanatory drawings, upon which 1 Figure l is a sectional elevation of a switch constructed according to the present Figure 4 is a section on line AB of- Figure 3.

Fig. 5 is a vertical sectional view, similar to Fig. 1, and showing the operating member and the contact member in another position.

Fig. 6 is a detail sectional view showing a modified construction in which a separate plate or washer is located between the bridge and the switch base, and forms a striking face for the contact arm.

Fig. 7 is a detail plan of the bridge.

Fig. 8 is a detail elevation showing the contact member and the contact carrying member assembled.

Fig. 9 is a detail elevation of the contact carrying member at right angles to Fig. 8.

In a convenient embodiment of the present invention, as applied to a tumblenswitch, the tumbler operating member 1 is pivotally carried by the bridge 2 and the contact member 3 is pivoted co-axially therewith. At a position below its fixed pivotal axis of movement the tumbler operating member is pivotally connected to the upper extremity of the spring element, the lower extremity of which is pivotally connected to the contact member at a position below the fixed axis of movement of the latter. In operation, the axis of connection between the spring element and the operating member is carried across the straight line extending between the fixed axis of the operating member and the axis of connection between the spring element and the contact member.

A fixed fulcrum abutment 4 is incororated on each side of the spring element. in aid spring element is adapted to come into contact with this abutment at a position intermediate its axes, so that the displacement of its upper axis by the operating member brings about a displacement of its lower axis in the reverse direction, thereby positively displacing the contact member initially, the subsequent displacement of the anemone contact member occurring under the influence of the spring element, which, acting under compression, extends longitudinally.

The fulcrum abutment members i may comprise tongues depending or extending rearwardly from the bridge.

The spring element may comprise a U- shaped member 5, from each side of the transverse part of which a trunnion 6 extends, said trunnions being aligned and located transversely to the plane of the U- member. The transverse part of the U-member may be provided rigidly or integrally with a sleeve-like portion 7 in which a rod 8 is adapted to slide. This rod has at its upper extremity an eye through which extends a pivot 43 by which said rod is pivotally coupled to the bifurcated lower extremity of the operating member.- The rod is encircled by a coiled compression spring 9. The limbs of the U-member 5 constitute the parts which come into contact with the abutment members 4 depending from the bridge socket 2.

The contact arm 3 also comprises a U- member, the transverse part of which occurs at the point at which the circuit-closing element 10 is carried. The limbs of the contact arm are extended in parallelism to the trunnion axis of the spring element. Said arms are also extended upwardly to the axis of the operating member. By this arrangement, as illustrated, when the switch is closed the movable contact surfaceand the operating end of the hand lever occur on opposite sides of a plane containing the axis of the contact member, and which plane is at right angles to the plane of the base. The upwardly extending parts of the contact arm are cranked outwardly from the parallel parts of the U to embrace the operating member. The perforations for the trunnions extend upwardly in the form of elongated slots beyond the crank formations so that the trunnions can be assembled downwardly. Said trunnions are retained in said slots by the pressure of the sprin The contact member 3 is stopped in both of its movements by the lower edge of the bridge 2, the abutment members 4 being adapted to depend from said lower edge in positions intermediately to the limbs of the contact arm.

The circuit-closing element 10 is also in the form of a U-member stamped from sheet metal. The transverse part of said U-memher is cranked or depressed to receive the extremity of the contact arm. The circuit closing part thus involves a transverse portion parallel with the transverse part of the contact arm, which transverse portion is at two points bent at right angles to embrace the end of the contact arm, and is then on each side of the contact arm bent through 180 degrees to extend away from the contact aeeaoea arm. The fixed contacts with which said circuit-closing element is adapted to engage may thus internally of the element extend beyond the face of the transverse part thereof, that is to say into recesses 15 formed between the side limbs and crank portion, withoutreducing the dimension (longitudinall of the contact arm) of the space with in t e same, which space may accommodate a spring quick make and break action. These relative formations of the circuitclosing element and contact arm serve to locate or to assist in locating the circuitclosing element laterally in relation to the contact arm.

Between the cranked part of the circuitclosing element and the part of the contact arm which it embraces, a U-shaped layer of insulation 18 is incorporated. The transverse part of the contact arm is perforated to receive a rivet 19, which rivet is adapted to pass through the layer of insulation and through a perforation 20 in the transverse part of the circuit-closin element, which perforation last mentione exceeds the diameter of the rivet. On its face opposite to that which is in contact with the insulating layer above mentioned the circuit-closing part is stepped around the perforation. This step is adapted to receive the base 'of a cup 21, and to locate it in relation to the circuit-closing part. Alternatively the circuit-closing part ma be provided with a projectionor projectlons adapted similarly to locate the cup. The said cup is concentrically perforated at its base with a perforation of size corresponding with that in the circuit-closing part. This cup is adapted to receive an annular body of insulatin material 22 such as micanite or a series 0 mica washers. 23 is a disc or layer of mica which may be placed below the annular body 22. The body 22, the perforated cup, the circuit-closing part, the layer of insulatin material, and the contact arm, are al clamped together by the rivet 19. As a result of this clampin process the insulating media may be forced to substantially fill the annular space around that part of the stem of the rivet which is encircled by the perforated cup and circuit-closing part. The head of the rivet may bear upon the disc 23 and body of insulating material within the cup and the stem may be riveted or enlarged at the inner surface of the transverse part of the contact arm. Alternatively, the rivet may be assembled from. within the contact arm and riveted at the external surface of the body of insulating material.

The cup or box-like member 21 may obviously be of circular, oval, square, rectangular, or other configuration.

The bridge 2 involves a socket '2 and is provided with the usual cars 24 which are perforated for attachment to the china base 25. I adapt the pivot pin 26 to pass through the socket and to extend at both extremities in contiguit with the ears. The fastening of the bridge is efiected by the use of stems 27, which may have heads (not shown) forming abutments for the ends of the pivot pin 26, or which (as shown) are perforated transversely to re-- 'carry the switch cover, but I may, as for instance in a case in which this screw thread is unnecessary, emplo a bridge which does not involve a socket 0 this character.

In Fig. 6 of the drawing, I show a modified construction in which a separate plate or washer 41 is located between the bridge 2 and the base, which plate or washer forms striking faces or shoulders 41' for the contact arm 3.

The base 25 may be substantially of octagonal form, alternate faces 36 being curved concentrically and intermediate faces 32 being in planes at right angles to each other. Ata mid-point in each of two opposite of these intermediate faces, indentations or semi-circular groovings 38 are provided to accommodate the fastening screws. Below each ear 24 of the brid e a plate 10 is secured. Said plate is per orated for the bridge fastening screw 27 to pass therethrough, and said plate or the bridge may have projecting abutments adapted by engagement with the bridge or said plate or the base, respectively, to prevent rotary deran ement of said plate. The said plate extends outwardly and is perforated coaxially or a proximately co-axially with the semi-circu ar groove 38 in the base. The fastening screw for the switch passes through this perforation, which may be countersunk. The plate 40 may thus constitute an earthing or ground connecting memher. It will be seen that the part of the switch 1 which is manipulated by the hand, is by virtue of the plate 40 in electrical connection with the switch fastening screw which is located in the groove 38, and passes into the conduit box or grounded part. In cases in which two switches are located side by side, a single fastening screw may be utilized to secure the adjacent sides of the said switches. These sides may be located in contact with each other so that the semi-circular groovings together form a perforation. I A single plate extends from operating member and a pivoted rocking member, both adapted to oscillate about one and the same axis, and a spring adapted to enable the movable contact to have a quick make and break action, by virtue of a toggle of which the said operating member forms one element, both axes of the other arm of which toggle are adapted in the action of closing or opening the switch to .move in arcs, the mean points of which are substantially nearer to the back of the switch base than is the pivot or axis of the said operating and rocking members, and in which, when the switch is closed, the movable contact surface and that end of the operating lever which is adapted to be actuated manually, occur on opposite sides of a plane containin the axis of movement of the said operating and rocking members, and which plane is at right angles to the back of the base, the arrangement being such that in the operation of opening the switch the said end of the operating lever passes through the said plane. Y

2. In an electric switch, a swinging contact element comprising a carrier member and a contact member, insulating material between said members, a rivet securing said members together and passing through said insulating material, said contact member having shoulders spaced from opposite sides of said carrier member, and said insulating material having abutting end portions bearing against the said shoulders, a cup fitted in a recess in said contact member, and an insulator in the hollow side of said cup, the said rivet also extending through said insulator and cup.

3. In an electric switch, an insulating base, a plate thereon, a bridge bearing on said plate and by which the movable members of the switch are carried, and' common fastening means securing said base, plate and bridge together.

t. In an electric switch, an insulating base, a plate thereon, a bridge bearing on said plate and by which the movable members of the switch are carried, and common fastening means securing said base, plate and bridge together, said base having grooves in its sides and said plate having openings over said grooves, said grooves and openings being arranged to receive fastening screws for the switch.

5. ln an electric switch, an insulating base, a plate thereon, a bridge bearing on said plate and by which the movable members of the switch are carried, common fastening means securing said base, plate and bridge together, and a pivot for the movable switch members and engaged with the bridge and also engaged with the said common fastening means.

6. An electric switch comprehending in combination, an operating member movable about a permanently stationaryaxis, a contact member also movable about a permanently stationary axis, a floating member pivotally connected to the operating member at a point eccentric to the axis of the latter and to the contact member at a point eccentric to the axis of the latter, resilient provision adapted to displace the toggle in either direction after it has passed its dead centre, and abutment provision with which said floating member is adapted to engage.

7. In an electric switch, an insulating base, a bridge, a pivot-mounted in said bridge, and means for securing the bridge to the base which means also retain the said pivot.

In witness whereof l have hereunto set my hand.

JUHN ASHWQRTH CRABTREE.

T ll

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