US2842640A - Cam-actuated, quick break electric switch - Google Patents

Description

July 8, 1958 R. s. RAGAN 2,842,640

CAM-ACTUATED, QUICK BREAK ELECTRIC SWITCH FiledDeo. 15, 1955 2 Sheets-Sheet l July 8, 1958 R. s. RAGAN 2,842,640

CAM-ACTUATED, QUICK BREAK ELECTRIC SWITCH Filed Dec. 13, 1955 2 Sheets-Sheet 2 INVENTOR.

United States Patent CAM-ACTUATED, QUICK BREAK ELECTRIC SWITQH Robert S. Ragan, Cincinnati, Ohio Application December 13, 1955, Serial No. 552,835 11 Claims. (Cl. 200-114) This invention relates to an electric switch suitable for the regulation of multi-phase power circuits.

Among the objects of the invention is the provision of a switch that bridges two lines of separated contacts with a fuse-carrying block which may be forced into close relation with the contacts by cam action.

Another object is the provision of automatic ejection of the block from a frame carrying the contacts when the switch is intentionally opened.

Another object is the provision of a lost-motion device which, in combination with an operating handle and a cam, effectively secures the switch in closed position so that it will not open from vibration.

Another object is to provide such relation between the switchbox and the ejected block that the block is retained in the box after ejection but at a distance sufficiently far from the contacts to prevent arcing.

Another object is to provide means to align the block for effective contact when seated and to break one preselected row of contacts upon ejection, before the other row is broken.

Briefly stated, the switch comprises a box, in the bottom of which there is a contact carrying frame mounted on arcuate springs. In the middle of the frame there is a cavity for the reception of a fuse-carrying block which is provided underneath with two pairs of coil springs, the rear pair having a diiferent strength from the front pair. The block is aligned by a channel in its lower body adapted to straddle a cam-actuating shaft which passes transversely through the cavity. The shaft carries a semi-circular internal cam on each side. of the frame. Each cam engages a roller on each side of the block whereby the block is forced downward into the cavity by the cams, thereby compressing both the coil springs and the arcuate springs. A lost motion device in one of the cams acts in conjunction with the adjacent handle, which is keyed on the cam shaft, to enable the handle to be moved to a limit position even after the block is fully forced down. Vibration, then, although it might cause some travel of the handle, would not necessarily open the switch. When the switch is opened, a preselected line of contacts is broken first so that all phases are deactivated at once. This action results from the coil springs under the line of contacts. first to be broken, being the stronger. Ejection of the block is stopped by thelid of the box, but in a position far enough out of the cavity to insure snufling of any'a-rc which may have been pulled out at the start of the break. Handholds are provided in the block so that it may be lifted out with the bare. hands for re-cartridging without danger.

Referring now to the drawings,

Fig. l is an oblique elevation of .the exterior of the switch, showing the container closed.

Fig. 2 is an oblique semi-plan view of the-fuse-carrying block.

Fig. 3 is-a similar view of the contact-carrying frame Zane-4e Ice attached to the floor of the fuse box and showing the cavity for the reception of the fuse block.

Fig. 4 is a plan view of a fragment of the frame and block assembly, showing the front contacts open.

Fig. 5 is a vertical section taken on the line 5-5 of Fig. 4 showing the block ejected until stopped by the box lid.

Fig. 6 is a fragmental view corresponding to Fig. 5 showing the block cammed down into the frame cavity with the springs compressed and the contacts closed.

Fig. 7 is a side elevation of the right hand cam showing the lost motion device.

in Fig. 1, 10 is a fuse box provided with a lid 11 in which there is an upward bulge 12. On the right side of the box 10 there is the end of a shaft 13 which, as will later appear, is a cam-operating shaft. A handle 14 is tightly attached to the shaft 13. The body of the box is provided with a limitstop 15 for the handle and the lid is perforated for a tab 16 through which the box may be locked.

Fig. 2 shows the fuse-carrying block 17 made preferably in its body 13 and sides 19 of high dielectric strength Bakelite. It is provided, beneath the body, with blocks 20 of the same material. The body 18 carries a plurality of fuse clips 21 for the reception of cartridge fuses 22 which at the rear adjoin an equal number of vertical copper contacts 23. Each side 19 is provided with a depressed handheld 24 and beneath it a roller 25, which is preferably a ball bearing. This roller is intended to cooperate with a cam, as will be explained. Beneath the body 18 there is a rear pair of coil springs 26 and a front pair of stronger coil springs 27, of which only one is visible.

Fig. 3 shows generally a frame 28 which comprises a sheet metal body in which there are rectangular perforations 30. On the front and rear top surfaces there are mounted a plurality of insulating blocks 31 which carry copper contacts. Of these contacts, the front row includes flat pieces 32 to which wires may be attached and uprights 33 intended to abut the ends of the cartridge fuses 22. The rear row comprises flat pieces 32 plus conventional wire attachment clips. Between the rows of blocks and contacts a cavity is thereby created, through which a cam shaft 13 runs transversely to the frame. At each end of the shaft 13, a semi-circular cam 34 is frictionally attached. Each cam has an internal slot 35 adapted to receive a roller and to draw it and the associated block 17 downward. In order to do this, either the slot may be directed so as to have a down ward slant or the cam itself may be mounted eccentrically, as shown, ot accomplish the same purpose.

Each cam 34 has attached to it by a pin 36, a crank 37 which is adapted to pass over dead center in regar to the shaft 13 when the cams have fully drawn the block 17 into the cavity in the middle of the frame 23. In passing over this dead center, a coil spring 38 which is wound about a reduced area portion 39 of each crank 37, is compressed against a tab 40' through which the crank 37 slides. The tab is welded to the inner wall of box 10. On the right hand side of Fig. 3, the spring 38 and tab 40 are not shown.

The frame 29 is mounted on arcuate springs 41 which are attached to the floor of the box 10. The purpose of these is to provide enough downward movement of the entire block and frame assembly to enable the cranks 37 to pass dead center. Compression of the springs 25 and 27 is sufficient to bring the assembly to dead center and the further downward movement allowed by the springs 41 enables the cranks to throw below the level of the shaft 13. In other words, they then point to the bottom of the box. The springs 38 are then tightly compressed.

Such position exerts a positive force tending to keep the cams from rotating back and consequently the block from being ejected.

A lost motion device is provided in the cams 34 to accomplish three objects. This device is a semicircular opening 42 and a pin 43 (see Fig.7 for greater detail) which has a radial sweep from the shaft 13. T he'device facilitates the passage of the cranks across dead center and on the return, when the switch is to be opened, it

It will therefore be seen that my switch provides secure closure and a quick break upon intentional opening.

Referring now to Fig. 4, it will be seen that there is a gap between the front uprights 33 and the fuse cartridges 22. Crank 37 is in the position of urging the cam 34 to its maximum retraction and the handle 14 hangs vertically downward.

This position of the assembly is shown in side elevation in Fig. 5. Here it will be seen that the spring pairs 26 and 27 are fully extended, the cam 34- is retracted and the block ejected until it touches the box lid bulge 12. This prevents falling-out of the block 17 in case the switch is mounted vertically or upside down. It will also be noticed that the springs 41 are fully extended. The shaft 13 is centered in a channel 44 created by extensions 45 of the blocks 20, thus using the solid alignment of the shaft to square the block 17 with the frame 28.

In Fig. 6, the block 17 is shown locked down into the frame 28 with the spring pair 27 compressed and the contact 23 touching the fuse cartridge 22. The block 17 no longer touches the lid bulge 12. The cam 34 has been rotated into maximum locking position. The block 17 is down sufficiently far so that shaft 13 is almost in contact with the lower edge of the block wall 19. Spring 41 is compressed. 7 All of this consequence of the downward pull of the earns 34 on the ball bearing 25 attached to the block 17 pulls the cartridge fuse 22 into intimate contact with the copper upright 33. At the same time, although not shown, the vertical rear contacts 23 are pulled down into edge contact with the rear horizontal copper strips 32, thus bridging the cavity 30 between the contacts on the frame 28.

Fig. 7 has been referred to. It shows clearly the spatial relations of the pin or screw 43 in the lost motion space 42 and the relation of the shaft 13 to the position of the crank pin 36 and the internal cam track 35. The eccentric mounting of the cam on the-shaft 13 is clearly apparent.

Certain changes or omissions can be made in the structure described without departing from the spirit of the invention. For example, the fuse cartridges 22 may be replaced by metallic conductors not intended to melt, or also by electrical measuring or indicating instruments. The lower springs may be dispensed with if the block coil springs 26 and 27 are retained. The cranks 37 and associated springs may be omitted. One cam, centrally located, might be employed in place of two. Other substitutions and omissions will occur to those skilled in the art and are permissible if within the scope of the following claims:

I claim as my invention:

1. An electric switch comprising a contact-carrying frame, a fuse-carrying block fitting within said frame, resilient supporting means between said block and said frame, cam means associated with said frame and cooperating bearing means on said block for pressing said block into good electrical contact with the contacts of said frame and auxiliary means, including a crank associated with said cam means and a spring associated with said crank for supplying an additional upward acting force to quickly break electrical conduction between said block and the contacts of said frame.

2. In an electric switch, a contact-carrying frame arranged to be electrically bridged, a fuse-carrying block made largely of insulating material, said block being adapted to fit within said contact-carrying frame resilient means on the lower surfaces of said block, which when said means are compressed, guide the ends of the fuses on said block into conductive contact with the contacts on said frame, and double symmetrically arranged cams, one on each side of said frame, for compressing said resilient means, and a bearing means on each side of said block for assisting said cams to force said block into said frame to form an electrical bridge therein.

3. An electric switch comprising a container, a contactcarrying frame within said container, a spring support for said frame, a fuse-carrying block fitting within said frame, resilient means on the lower surface of said block, insulating means extending higher than the fuses carried by said block and a closure for said container adapted to press, when closed, said block and the fuses thereon toward conductive relation with the contacts on said frame and manually-actuable cam means for further resiliently pressing said fuse-carrying block into low resistance relation and potential quick release with the contacts on said contact-carrying frame.

4. In an electric switch, a frame, electric contacts on each end of said frame, a block adapted to fit between the ends of said frame, fuses carried by said block, said fuses being adapted to bridge said contacts when said block is recessed in said frame, compressible springs under said block, a shaft passing under said block, a roller on each side of said block, a plurality of cams having inner bearing surfaces said cams being attached to said shaft and each adapted to contact one of said rollers to force said block downward into the recess of said frame and to compress the springs below said block whereby to establish good conductive contact between said con tacts and said fuses and an operating lever attached to an end of said shaft through which the necessary compressive force may be applied and released through said shaft and cams and upon release of which said block will be quickly pushed up by said springs from said frame opening whereby speedily to break the electrical contact previously established through the fuses.

5'. An electric switch according to claim 4 in which those springs under the block which are first to be released by the cam action have stronger springs than those last released whereby said block is quickly ejected upward from said frame in a substantially vertical plane in regard to the frame when the latter is horizontal.

6. An electric switch comprising a container, a frame resiliently mounted on the floor of said container, said frame bearing contacts on each end and having a central cavity, a fuse bearing block made largely of insulating material and bearing fuses and clips therefor on its top surface adapted to engage said contacts on the frame, connected revoluble double cam means for holding said block in said frame cavity, a bearing on each side of said block for engagement with said cam means, resilient means positioned under said block to be compressed under the influence of said cam means and to eject said block when it is released by said cam means and hand-holds on the sides of said block whereby the block may be lifted entirely clear of said frame and container after its ejection from the cavity."

7. An electric switch according to claim 6 and in addition a manually operable handle'mounted on the container, a shaft extending crosswise of said container and revoluble by asid handle to actuate said cam means.

8. In an electric switch of the type in which a cam is manually turned to force a fuse-carrying block into a contact-carrying frame, the improvement which comprises a handle, a shaft to which said handle is connected, an internal cam secured to said shaft and said handle, said cam having a cut-out portion extending partially about said shaft, :1 pin extending radially from said shaft into said cut-out portion to provide a st motion device, a coil spring wound about said handle and arranged to be compressed when said handle is operated to force the fuse-carrying block into the contact-carrying frame, and to extend upon the reverse of this motion whereby to revolve said shaft and pin through said lost motion device and transfer its energy to said cam to release said block to break electrical contact quickly.

9. In combination in an electrical switch a resiliently mounted contact frame, a container in which said frame is enclosed, a fuse-carrying block adapted to fit into said frame, means for forcing said block into said frame and to resiliently release it therefrom and a lid on said container positioned when closed, to retain said block when released in the container in no-electrical contact position.

10. An electric switch comprising a container, a contactcarrying frame resiliently mounted in said container, said frame having a cavity in its middle portion, a shaft extending through said container and across said cavity, a handle and a pair of internally surfaced cams carried revolubly on said saft one on each side of said frame, an insulating block adapted to fit into the cavity and to closely straddle said shaft wherebyto align said block and to bring a plurality of cartridge fuses carried by said block into good electrical conductivity with said contacts and ball hearings on each side of said block positioned to be engaged by the inner surfaces of said cams whereby said block can be manually forced into resilient contact with said frame and ejected therefrom upon reversed movement of said shaft and cams by said handle.

11. In combination, in an electric switch, a frame hav- 5 ing a depression extending across its middle, horizontal contacts at one end of said frame, vertical contacts on the other, a cartridge-type fuse-carrying block adapted to fit partially within the depressed part of said frame, and to bridge the contacts thereon through the fuses, a box having a lid said box being adapted to contain in alignment the frame and block together, a shaft extending through both sides of said box and through the depression in the frame, a handle on one side of said box for rotating said shaft, a grooved semicircular cam frictionally and eccentrically mounted on said shaft adjacent both sides of said frame and adapted to be rotated with said shaft, bearing means on both sides of said block adapted to be engaged by said cams whereby said block may be forced into the depression of said frame and into electrical "elation with the contacts thereon, a lost motion device associated with the mountings of said cams, a crank eccentrically attached to each cam adapted to slip over the cam-bearing shaft as dead center upon locking and releasing said block from the depression by operation of said cams and a coil spring Wound about each crank for imparting a quick upwardly directed force to said block through said cams when said block begins to be released by the retraction of said handle from the locked position.

References Cited in the file of this patent UNITED STATES PATENTS 1,405,271 Burton Jan. 31, 1922 1,424,579 Mason Aug. 1, 1922 1,491,223 Casner Apr. 22, 1924 1,648,853 Luther Nov. 8, 1927 1,733,126 Johansson Oct. 29, 1929 1,835,983 Hammerly Dec. 8, 1931 2,117,480 Harvey May 17, 1938 FOREIGN PATENTS 207,956 Great Britain Dec. 13, 1923

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