US2001080A - Electrical switch - Google Patents

Description

y 19351 J. 5. THOMPSON ELECTRICAL SWITCH Filed March 13, 1934 3 Sheets-Sheet l km MM M mmaw wk 0 NM INVENTOR Josey? 5 7790/77 950/7 p Q m ATTORNEY y 1935. .1; s. THOMPSON ELECTRCAL SWITCH Filed March 13. 1934 3 SheetsShee 2 I m mHrm-H M \Q. Q.

Jose 0h 3 7770 ATTORNEY May 14,1935.

J. S. THOMPSON ELECTRICAL SWITCH Filed March 13, 1954 S'Sheets-Sheet s m m h lh -H INVENTOR Jose 5v; 5 Tho/730500 ATTORNEY Patented May 1935 PATENT OFFICE aotnoso ELECTRICAL swrrcn Joseph, S. Thompson,

signer to San Francisco, CailL, as- Paciflc Electric Manufacturing Corporation, San Francisco, Calif., a. corporation or California Application March 13,

4 Claims.

This invention'relates generally in the construction .of electrical switches for use in ,con

. junction with electrical power distribution systems.

It is an object of the invention to provide a switch of the above character, which will be well adapted for operation by an electric motor or like device without danger of improper closing or breakage of parts resulting from varia- 1o tions in the degree of movement of the operating member. In this connection, my switch is characterized by a relatively wide permissible. angle of overthrow of the operating member from that position corresponding to complete initial 15 closing of the switch.

Another object of the invention is to provide an improved arrangement for counterbalancing the switch blade, whereby there will be no undue speeding-up of the operating motor in opening 20 the switch, when the blade is arranged to swing downwardly.

A further object of the invention is to provide a construction and a co-ordination of parts whereby breakage of certain elements will not as cause the switch blade to drop open.

Another object of the invention is to provide ,an improved means for applying pressure to the electrical contacting areas of the switch.

Further objects of the invention will appear at from the following description in which the preferred embodiment of the invention has been set forth in detail in conjunction with the accompanying drawings. The appended claims are .to be afforded a range of equivalents consistent 36 with the state of the prior art.

Referring to the drawings: Fig. 1 is a side elevational view illustrating a switch incorporating the present invention.

Fig. 2 is a bottom plan view of the switch 40 shown in Fig. 1.

Fig. 3 is a cross-sectional detail showing the preferred construction of the switch blade andits co-operating contact. i

Fig. 4' is a view similar to Fig. l, but showing 46 the parts of the switch in a different operating position. v

Fig. 5 is a cross-sectional detail taken alon the line 5-5 of Fi 1.

Referring first to Fig. l of the drawings, the 60 operating parts of my switch are shown carried by a plurality of insulators In, H and 12, which in turn are secured to a structure support memher It. The blade I of the switch is carried by leverage mechanism IB' which in turn is se- 55 cured to the lower end of insulator ll. One

1934, Serial N0.715,263

end of blade |4 co-operates with a' relatively stationary contact I6, which in turn is carried by the lower end of insulator 10. As representative of suitable means for applying motion to the. leverage mechanism I5 to effect opening and closing movements ofv theswitch blade ll, insulator I2 is journaled with respect to the structure support l3, whereby it can be rotated axially by a suitable electric motor or like device. A shaft I8 is coupled to the lower end of insulator l2, and secured to this shaft there is an operating member or lever l9. As will be presently explained, this lever is is suitably connected to the leverage mechanism I5 to effect operation of the switch. A desirable form of. contact I6 is illustrated more clearly in Figs. 2 and 3. It is formed of suitable metal, such as brass or bronze, having a pivotal connection 2! with a bracket 22, this bracket being in turn mounted upon the lower end of insulator it. The outer edge or face 23 of the contact is of sufficient width to afford an adequate electrical contacting area, and is formed on a contour such as shown in .Fig. 3 to afford a tapered lower end portion 24. The contact is urged or biased in a clockwise direction about the pivotal connection 2|, by means of a compression spring 25. A lug 2i engaging a fixed shoulder 28, serves to limit movement in such direction. An electrical conductor 29 is connected to the contact l6, and, in conjunction with the terminal member 3|. facilitates making electrical connections with the circuit in which the switch is to be incorporated.

' A desirable construction for the switch blade H is shown in Fig. 3, and is as follows:-The blade for the major portion of its length consists of a rigid metal tube 32. Secured to one end of tube 32 there is a contact member 33, which is adapted to cotively stationary contact l3. As illustrated, contact 33 is in theform of a yoke made of suit- .able' metal, such as brass or bronze, having a collar 34 for attachment to the tube 32. The inner face 36 of this yoke is relatively wide compared with the width of contact I6, and is of amplearea to afford good electrical contact withthe edge face 23 of the contact I6.

In its preferred construction, the switch blade is also provided with a pressure contact to make possible tight clamping engagement with the contact "5 when the switch is closed. Thus, in the construction illustrated, a pair of aligned rods 31 and 38 are slidably disposed within the tube 32. One end of rod 31 carries a pressure operate with the rela- 40 2 contact 88, which in this instance is semi-cylindrical in form. A. spring-biased lost motion to rod 88. The spring therefore serves to urge" rods 81 and 88 apart, and such movement is limited by collar 88 mounted upon rod 88. Rod 88 is also urged in one direction by a compression spring 81. Thus, in the detail shown, spring 81 is disposed within a sleeve 88, which in turn is fixed to the tube 82. One end of the spring is seated upon a stationary abutment 88, while the other end is seated upon a collar 8| secured to rod 88. i

That end of rod 88 which projects from the end of tube 82 isadapted to be actuated by a cam, as wil1,presently be explained, and it is therefore shown carrying a cam roller 82. Movement of the rod 88,.under the urge of spring 81, is limited by engagement of collar 5| with the end tube closure 88.

With the switch blade assembly described above, it is evident that when rod 88 is forced inwardly with respect to tube '82, such movement is initially accompanied by movement of rod 81, until the pressure contact 88 engages the relatively stationary contact l8. Thereafter, movement of rod 81 and pressure contact. 88 is arrested, and further movement of rod 81 is taken up bythe lost motion connection' formed by sleeve8l. Contact 88 is therefore pressed upon the stationary contact l8, in accordance with the compression of spring 82. Such pressure not only servesto establish good electrical connection between pressure contact 88 and the adjacent surface of contact l8, but

also serves to tightly press together and make good electrical contact between the faces 28 and 86. In Fig. 3, rod 88 has been shown forced inwardly to, such an extent as to secure the desired pressure engagement. While the springbiased lost motion connection formed by sleeve 8| and spring 82 is deemed desirable, it is not essential, since other means may be provided toaiford tact 88.

The leverage mechanism I 8 can best. be 'explained by reference to Figs. 1 and 2. In the detail construction illustrated, one end of the tube 82 is gripped bya clamp 88, whicli'in turn I8 is turned, as by rotating 88 is swung about the axis 82, to swing the axis of pivotal connection 88 carries a pair of spaced arms 81. Arms 81 are provided with a pivotal connection 88 with an L-crank 88. The arms 8| of this crank are provided with pivotalconnections 82 to a bracket. 88, this bracket in turn being secured to the lower end of insulator II. The arm 88 of crank 88 is connected to a link 88 which in turn is connected to the crank 18. Thus, when crank insulator l2, crank of pivotal connection about an arc of a circle.

In addition to the leverage mechanism just described, means is provided for determining or controlling the motion applied to blade 18 in response to rotation of'crank 'I8, and particularly to provide for continued movement proper retention pressure upon con-.

of the crank l8 after the free end of theblade has been elevated to closed position. Thus, in the construction illustrated (Fig. 2) a cam roller 81 is journaled to the extremities of arms 81. This roller engages within cam ,slots 88 formed in the parallel depending cam plates 68. The cam plates are stationary, as for example by mounting them upon the bracket 68. A desirable shaft I8 is journaled. The plunger rods 18 of' these slots are pivotally' connected to the extremities of arms 81. The counterbalancing forces are thus appliedin such a manner as to tend 'to'rotate arms 81 in a clockwise direction. as viewed'in Fig. 1. It is evident that a single spring counterbalancingunit of proper design will suflice in place of the duplicate units shown. In order to steady the lower end of rotatable insulator l2, brackets 88 and 12 are connected together by'tie rods 18. If desired, these rods can also be incorporated as conductors for the electrical circuit. Thus, as illustrated in Fig. 1, the blade is electrically connected to the tie rods by means of flexible conductors 18. Electrical connection to the tie rods 18 the terminal member 11.

Reference has previously been made to the factthat the pressure contact 88 is preferably actuated by cam means. Referring particularly to Fig. 1, a secondary cam 8| is shown carried by bracket 68, intermediate thespaced cam plates 88. when the switch is in the closed position shown in Fig. 1, the surface of this cam is engaged by roller 82, and the roller occupies a position with respect to the 'blade such -that pressure contact 88 isbeing forced into tight engagement-with the relatively stationary contact I8. I a Operation of my switch is as followsz-An optimum closed position for the switch blade is illustrated in Fig. 1. If it is desired to open the switch, an electric motor or like device serving .to rotate insulator I2, is energized. Rotation of crank l8 causes crank 88 to be rotated in a counter-"clockwise direction, as shown in this figure, thus causing the cam roller 81 to move downwardly within the portions 88a of the cam slots 68. As long as the camroller is within the slot portions 88a, the angles assumed by arms "in their downward movement serve to retain the free end of the switch blade at a substantially fixed-elevation with respect to the contact 18. Thus, as shown in Fig. 4, when the cam roller 81 is at about the lower extremity of cam slot portions 880, the contact member 88 on the end of the blade has not been lowered to any materialdegree with respect to the contact I8. Slight lateral and angular movements of the blade are accommodated by the pivotal mounting of contact l8. 'Before the cam roller 81 has reached the lower extremity of cam slot portions 88a, cam-roller 82 passes thelower extremity of cam 8|, thus causing the pressure contact 88 to-be retracted under the urge of springs 82 and 81.

Further rotation of crank 88 causes cam roller can be made by contour for the camslots is illustrated in Fig. l.

'61 to progress along the cam slot portions 68b,

the switch.

In closing the switch, a reverse torque is applied to' insulator l2, and crank 59 is rotated in a. clockwise direction as shown in Fig. 1. By the time cam roller 61 has reached the lower extremities of cam slot portions 680., the free end of the blade has been swimg to the position illustrated in Fig. 4, although the pressure contact 39 is still retracted. Final rotation of the crank 59 in a clockwise direction brings roller 52 into engagement with the surface of cam 8|;

' thus causing the pressure vcontact 39 to be urged into tight engagement with the contact It is evident that from the instant pressure contact 39 has been properly urged against the contact l6, crank 59 may overthrow'to a considerable degree, without detrimental results. Likewise, when the switch blade is in the position shown in Fig. 1, lever I9 is in dead center position with respect to link 66, so that further turning movement of lever 19 causes a lowering of cam roller 91 in slot portions 68a. Thus, a tolerance is afforded on both sides of the dead center position of crank 19, within which contact 39 remats pressed against contact [6. To

r example, the motor is arranged to normally arrest closing movement of lever l9 when" this lever is in dead center position with link 65. As lever l9 approaches suchdeadcenter position, contact 39v is first pressed upon contact it, during initial upward movement of roller 61 in slot portion 6801.. Thereafter, lever l9 may continue say 13 degrees to dead center position and 13 /2 degrees past dead center position,

while theswitch remains closed; Therefore lever it may stop anywhere within a total tolerance of 2'7 degrees, and if such tolerance is accidentally exceeded, no harm will result, except that'the switch will beopened.

A further characteristic of my switch is that if certain parts become broken, as for example the arm 64 of crank 59, the link 66, or the crank t9, the switch will remain closed and will not immediately drop to open position. This is because, when the switch is closed, the stationary contact I6 is being tightly gripped by the pressure contact 39, and also because of the'angularity of cam slot portions 680. with respect to the application of counterbalancing forces from the counterbalancing units 1]. Likewise, in the event the counterbalancing units become disrupted, the switch will not drop open, because of,

the friction occasioned by the lateral thrust of cam roller 61 upon the sides of cam slot portions 68a. The cam slots 68- not only modify movement applied to the blade !4 to secure the results described, but also serve to control the application of counterbalancing forces so that the parts are properly counterbalanced during bothiopening and closing of the switch. Thus,

there will be no undue speeding-up of the operating motor'when the switch is being opened.

In the particular modification described herein, the switch has been mounted for downward swinging movement of the blade to open position. However, it is evident that the switch can be variously positioned, depending upon the conford a substantial amount of continued movement of the crank afterthe blade has been moved to substantially closed position with respect to the stationary contact, and having another portion thereof formed to afford swinging movement of the blade between open and closed positions, and counterbalancing means connected to said lever arm, whereby said cam serves to simultaneously vary the effective counter-balancing of the blade.

2. In an electrical switch, a movable blade, 'a contact member secured to one end of the blade, a relatively stationary contact adapted tocooperate with the contact member of the blade, means including an operating member serving to carry and permit swinging movement of the tween the pressurecontact and the first-named contact member of theblade.

3. In. an electrical switch, .a blade having a contact member secured to one of its ends, a

relatively stationary contact adapted to co-operate with the contact member of the blade, with the blade contact member engaging one side face of the relatively stationary contact,

'means including an operating member serving to carry and permit swinging movement of the blade between open and substantially final closed positions, said last means affording a substantial increment of continued movement of the operating member after' the blade has been moved to .substantially final closed position, an additional pressure contact movably carried by the blade and adapted to engage the opposite side face of said relatively stationary contact,

and means including a cam, operating within the limits of said continued movement, for urging'the pressure contact into forceful engagement with the stationary contact whereby the stationary contact is tightly clamped between the pressure contact and the first-named contact member of the blade. I

4. In an electrical switch, a blade having a contact member secured to one of its ends, a relatively stationary contact adapted to co-operate with the contact member of the blade, with the blade contact member engaging one side face of the relatively stationary contact, means including an operating member serving to carry and permit swinging movement of the blade between open and substantially final closed positions, said last means also including a camserving to modify motion of the blade and affording a substantial increment of continued movement 01 the operating member after said one end of the blade has been moved to substantially final closed position, an additional pressure contact movably carried by the blade and adapted to engage the opposite side face 01' said relatively stationary contact, and means includlng a seeand cam, operating within the limits or said continued movement; for urging the pressure contact into forceful engagement with the stationary contact whereby the stationary contact is tightly clamped between the pressure contact I and the first-named contact member 01 the blade.

JOB. 8. THOMPSON.

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