US2395683A - High voltage safety switch - Google Patents

Description

' Feb. 26, 1946. F. E. RUNGE HIGH VOLTAGE SAFETY SWITCH Filed May 1, 1944 IN V EN TORJ anli'l? QM ATTOEWEX Patented F eb. 26,1946

UNiTEo "rs AT NT FFHCE I 2.395.683 men VOLTAGE SAFETY swrrcn Frank E. Range, Haddon Heights, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application Mi. 1, 1944, Serial No. 533,601

9 Claims.

The present invention relates to electron microscopes and other hig voltage electrical apparatus, and more particularl to an assembly operated by the opening of a door 'or doors of the housing for the high voltage units.

Some of the objects of the present invention are: to provide a safety grounding means for high .sembly in response to the opening of a door or doors; to provide a compact, positive and foolproof mechanism for grounding housed high voltage units when a door or doors of the housing is opened; and to provide other improvements as will hereinafter appear.

, In the accompanying drawing,

Figure 1 represents a longitudinal section, in

part, of one form of grounding mechanism embodying the present invention;

Figure 2 represents a section on line II-II Fig. 1;

Figure 3 represents a fragmentary plan of the plunger parts in position as restrained by the closed doors;

Figure 4 represents the plan of Fig. 3 showing the position of the parts when opening of the left door; I

Figure 5 represents a section on line VV of Fi Figure 6 representsa section on line VI-VI of Fig. 4;

Figure 7 represents a section on line VIIVII of Fig. 3;

- Figure 8 represents a section on line VIII-VIII of Fig.4; and

Figure '9 represents a detail perspective of one set of the ground rod actuating'means.

Referring to the drawing, one form of the pres ent invention is shown mounted on the rear wall 9 of the housing for the high voltage units of an electron microscope, and in position to be controlled by the two opposite doors l0 and I I which serve to gain access to the interior of the housing.

For contacting conductors, condensers or other high voltage parts, there is provided a plurality of grounding rods l2, usually of different lengths released by the in order to reach parts at different distances from the wall 9. Each rod l2 has one end looped about an actuating sleeve i3, at spaced interval for free turning movement thereon, and is held against. lengthwise movement on the sleeve lit by a pair of collars l4 and I5 which are fixed to the sleeve l3 by set screws i6 or the like. The collar i4 is provided with a pick-up pin i1 pro- .iecting laterally and parallel to the sleeve i3 to engage one side of the adjacent rod i2, and the collar i5 has a like pick-up pin it projecting laterally and parallel to the sleeve to engage the oppositeside of the same rod |2.- Thus turning of the sleeve i3 in a clockwise direction, as seen in Fig. 9, will cause the pins I to flip the rods i2 clockwise considerablyto shift them past the dead center of the sleeve so that each rod is forced against, or finally falls by gravity against, its adjacent conductor. To return the rods l2, the sleeve i3 is turned counter-clockwise and the pins it then pick up the respective rods l2 and re-- turn them to contact with the wall 9. On this return movement the pins l8 remain in contact with the rods l2 to hold them against the wall 9.

It is important that the collars l4 and i 5 be rotationally adjusted and fixed upon the sleeve l3,

so that the pick-up pins i1 and it have a predetermined arc of travel to pick up the rods l2 in the required manner.

For imparting rotary movement to the sleeve l3, it is supported by and is freely rotatable on a tube 8, and receives its motion by means of a cam followeror pin 20 fixed to a plunger 2! and projecting radially therefrom to traverse a cam slot 22 in the tube 8 and enter a linear slot 23 in the sleeve i3. The slot 23 is parallel to the axis of the sleeve l3 and has a uniform width to slidably receive the cam follower or pin 20. The cam slot 22 is in the form of a spiral across the juxtaposed face of the tube 8. It will thus be seen that relative movement between the pin 20 and the tube 8 will shift the pin 20 against one or the other side of the slot 23, depending upon its direction of travel, and thus turn the sleeve H as required to shift the rods 12 to grounding position or opposite thereto.

For actuating the pin 20, the plunger 2! is of a length to project from one end of the tube 8 into the path of the door Ii, so that as the latter is closed it will contact the end of the plunger 2| and shift it axially of the tube 8 (to the left as seen in Fig. 1 thereby to cause the pin 20 to turn the sleeve I 3). Rotation of t'he sleeve i3 from the opposite end of the mechanism is accor iplished by the axial movement of a thrust-pin 24 permitting endwise fixed to and projecting radially from a plunger 25 to pass with a snug fit through a hole in the tube 8 and traverse an opening 28 in the sleeve i3. This opening 26 is of such dimensions as to allow unrestricted linear and rotary motion of the pin 24 with respect to the sleeve l3. The free end of the thrust-pin 24 is arranged to ride in a slot 21 formed between two superposed lugs 28 fixed to the wall 9. The slot 21 is longer than the maximum stroke of the thrust-pin 24 and its function is to prevent turning of the tube 8 while movement thereof. The plunger 25, firmly fixed in the tube 8, projects from the end of the sleeve [3 into the path of the door l0, so that as the latter is closed it will contact the end of the plunger 25 and shift it axially of the sleeve l3.

For maintaining the plungers 2| and 25 projected for contact with the respective doors l8 and H, a compression spring 29 is interposed between the opposed ends of the two plungers and functions to propel one or the other, or both outwardly when either or both doors are opened.

In order to support the assembly on the wall 9, brackets 30, in the form of apertured angle irons 32, carrying bushings 33 to receive guide the respective plungers 25 are provided. These bushings 3| allow free turning movement of the sleeve 13 as will be understood.

The operation of the device is as follows: Assuming both doors are closed, the parts will be in the position shown in Figs. 1, 2, 3, and ,7. When the door i0 is opened the spring 28 using the plunger 2| as a fixed abutment propels the plunger 25 outwardly, thereby shifting the thrust pin 24 to the left (as seen in Fig. 4) and causing the tube 8 to follow its movement. In so moving the tube 8 pulls the cam slot 22 along with it and thereby moves the cam follower pin in the direction to turn the sleeve i3 in a clockwise direction (Fig, 9), thereby causing the collar pickup pins ll to engage the respective rods l2 and flip each over to its grounding position. When the door I0 is swung back to closed position the reverse action of the parts'takes place and the pick-up pins l8 are caused to engage the respective rods l2 to return them in a positive manner to inoperative position. With both doors now closed again, it will be assumed that the door H is opened. The spring 28 now uses the plunger as a fixed abutment and propels the plunger 2i outwardly, This movement is transmitted to the rock-pin 20, which cams the sleeve IS in a clockwise direction to flip the rods l2 to grounding position through the action of the pick-up pins ll. When the door II is closed the plunger 2| is pressed back against the tension of the spring 29 and the pin '20 now cams the sleeve 18 counter-clockwise so that the pick-up pins l8 return the respective rods l2.

In case both doors l8 and II are open, the

closing of one door merely results in the wholeinternal assembly within sleeve l3 sliding as an articulated unit, and no rotary motion of the sleeve l3 can take place because there is no fixed abutment against which the spring 29 can react.

I claim as my invention:

1. A device for grounding electrical conductors, comprising a tube, two plungers in said tube, a spring normally compressed between said plungers to cause said plungers to project at opposite ends of said tube for respectively contacting two doors, said plungers and spring having a minimum length when said doors, are closed and an aseaeas expanded length when either door is opened, a grounding rod, and means Operated by the expanding motion of said plungers, as one or the other of said doors is opened, (or moving said rod from an inoperative position to a grounding position.

2. A device for grounding electrical conductors, comprising a tube, two plungers in said tube, a spring normally compressed between said plungers to cause said plungers to project at opposite ends of said tube for respectively contacting two doors, said plungers and spring having a minimum length when said doors'are closed and an expanded length when either door is opened, a grounding rod, and means operated by the retracting motion of said plungers as one or the other of said doors is closed, for moving said rod from a grounding position to an inoperative position.

3. A device for grounding electrical conductors, comprising a tube, two plungers in said tube, a spring normally compressed between said plungers to cause said lungers to project at opposite ends of said tube for respectively contacting two doors, said plungers and spring having a minimum length when said doors are closed and an expanded length when either door is open, a grounding rod, and means operating as a function of the length of said spring and plungers for moving said rod from one position to another.

4. A device for grounding electrical conductors, comprising a tube, two plungers in said tube, a spring normally compressed between said plungers to cause said plungers to project at opposite ends of said tube for respectively contacting two doors, said plungers and spring having a minimum length when said doors are closed and an expanded length when either door is open, a rounding rod, means operated by the retracting motion of said plungers as one or the other of said doors is closed ior moving said rod from a grounding position to an inoperative position, and means rendering said last means ineflective if one door is closed while the other is open.

5. A device for groundin electrical conductors. comprising a. sleeve, a tube in said sleeve and relatively slidable, means between said sleeve and tube for translating linear motion of said tube into rotary motion 0! said sleeve, a grounding rod, means actuated by said sleeve for swinging said rod from one position to another and means arranged to be actuated by the opening or closing or an associated door to move said rod from an ungrounded position to a grounded position during a door opening movement and from a grounded position to an ungrounded position during a door closing movement.

6. A device for grounding electrical conductors, comprising a sleeve, a tube in said sleeve and relatively slidable, means including a cam slot in said tube and a pin, for imparting rotary motion to said sleeve, a grounding rod, means actuated by said sleeve for swinging said rod from one position to another, and means arranged to be actuated by the movement of an associated door I for causing said pin to move in a direction to means actuated by the opening 01' either door for causing said mounting means to move said rod away from said wall and into contact with said conductor whereby I said conductor is grounded.

8. In an electron microscope, the combination of a wall forming a portion of a housing, oppor sitely disposed doors for said housing, a grounding rod, means mounting said rod for movement towards and away from said wall, a current conductor in the path of movement of said rod, and means actuated by the closing or one door after the other door is closed for causing said mounting mean to move said rod out of contact with said conductor and into contact with said wall.

9. A device for grounding electrical conductors,

' comprising a sieeve, a tube relatively slidable in of said sleeve for operating said turning means to cause said rod tomove to a grounding position, and means arranged to be actuated by the opening of a door at the other end of said sleeve for operating said turning means to cause said rod to move to the same grounding position, said last actuating means being rendered ineffective when the first actuating means has functioned.

FRANK E. RUNGE.

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