US1465420A - Piston switch - Google Patents

Description

HAQSAZQ) Aug. 21, 1923;

G. H. CHAPMAN PISTON SWITCH Filed April 10 III/I 2 2921 J 7100mm? 560790 H Chapman;

and

Patented ne 21,1923.

: chosen H. CHAPMAN,

insane OF CHICAGO, ILLINOIS.

ris'rou swrron.

To all whom it may concern:

Be it known that I, GEORGE H. CHAPMAK, aacitizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Piston Switches, of

which the following is a specification.

This invention relates to electric switches of the piston or push-button type, the invention being designed mainly, although not exclusively, as an improved piston I switch for use on pipe-organs to 'close' electric circuits for magnets which operate stop combination switches. 1

Among the objects ofthe invention are, to provide a piston switch of greater durability steadiness of movement than the switches of this type heretofore used, to

provide a piston switch permittingone side of the circuitto be grounded onto the piston guide orshell, thus saving room which has heretofore been taken. up by the feed contact, to provide a piston switch adapted to employ two or more wide contacts in co-operation with the movable element of the switchwhich enables .a heavy current to be used and distributes the arcing over a large contact area, to prov de aconstruction wherein the movable member of the switch is-securely held against turning on its axis while being guided in its endwise movement, to provide a construction which may readily be'assembled and disassembled for purposes of renewals and repairs; and, generally, to provide an improved and more eflicient piston switch of the character described.

These, and other objects and advantages of the invention, will'be apparent to persons skilled inthe art as the same becomes better understoodby reference to the follow ing" description, taken in connection with the accompanying drawing in which I have illustrated'one practical embodiment of the invention, and wherein Fig. 1 is a front elevationof a fragment of the key shp of an organ console having my improved piston switch'applied thereto;

Fig. 2 is a top plan view of Fig. 1;

-Fig. 3 is an enlarged transverse section V on the line 3-8 ofFig..2

- Fig. 4; is a: bottom plan, viewed from the under side of Fig.2; and

Fig. 5- is a rear elevation, as seen from thetop of Fig. 4:.

-Referring. to the drawing, designates Application filed April 10, 1922. Serial No. 551,097.

as an entirety a short section of a bar of wood or like non-conducting material, constituting a part of the front pin-rail, and 11 is the key-slip secured to the bar by screws 12. In, and crosswise of the bar 10, 1s formed a round socket13, the openend of which registers with a hole 14: formed through the key-slip 11. Within the socket 13 and hole 14 is fitted a hollow cylindrical shell 15 of brass or other electrically conductive material. The shell 15 is closed at its rear end by a centrally apertured wall 16 formed with a central annular boss or 'mandrel 17. The bar 10 on its lower side is formed with a transverse groove 18 preterably located in the same vertical plane with the axis .ot'the shell 15.

' Slidably mounted in the rear wall 16 and boss 17 of the shell is the stem 19 of a slidable contact member, this latter carrying an integral contact head 20 consisting of a rectangularly bent extension of the stem 19, and a guide member 21 formed as 'a rectangularly bent extension of the head 20, paral lel with the stem 19 and slidably fitting theguide groove 18. On the head 20 is preferably soldered a contact strip 22 of silver or other metal suitable for electrical contact I purposes.

Attached to the bar 10 are a pair of leaf spring contacts 23 and 2 1 which, as clearly shown in Figs. 1 and 5, overhang the head 20 of the slidable contact member; the members 23 and 24 being disposed at slightly ditiereut angles, as shown in Fig. 1, so that, as the slidable contact member is pushed inwardly, contact is first made with the strip 23.. and later with the companion strip 24.

Slidably mounted in the shell 15 is the piston 25 of insulating material, carrying on its outer end the usual ivory push button 26. Theinner end of the piston 25 is countersunk to form a well or socket 27, from the bottom of which latter extends a tapped hole 28 into which the outer threaded end-of the contact stem 19 is secured. Seated and guided within the well 27 of the plunger is the first-touch coil. compression spring 29, the other end ofwhich is centered on the boss or mandrel 17 and abutsagainst the bottom wall 16 of the shell. Surrounding the spring 29 and footed on the rear wall 16 of the shell is the second-touch and heavier coil spring 30 that is called into action through contact with the inner end of the piston only after the latter has been pushed inwardly far enough to close the first-touch contactwith the strip 28.

Mounted on and extending lengthwise of the bar 10 is a metal feed strip 31 that is electrically connected to the shell 15 by a wire 32 (Fig. 3).

In practice, the feed strip 31 (which may serve a number of piston switches mounted side by side lengthwise of the bar 10) is connected through a circuit wire, indicated at 33 inFig P J, with one side of a battery or'other source of current, while circuit wires 34 and (Fig. 5) lead from the contacts 2st and 23 through electromagnets which. in turn ogerate stop combination switches, and thence to the other side of the battery or other current generator, hen the piston 25 is pushed inwardly far enough to close the circuit through contacts 22 and 23, the first-touch compression spring 29 alone is compressed. Ii": it is desired to closethe other circuit through contacts 22 and 24, the piston is pushed all the way in, callinginto action the second-touch compression spring 30. The instant the piston is released, it is instantly returned by the Lao springs to outermost position; a felt strip 36 (Fig. 3) preferably being employed as a buffer to limit the outward movement of the-piston through engagement with the contact head 20. 7

Among the advantages which the described structure possesses there may be mentioned the-following: The usual felt bushiiig'encircling the piston, which soon wears out and permits a wabbly movement of the latter, and consequently a lost sidewise motion of contact, as well, is, in the present. structure, replaced by the metal shell 15 which affords a long and steady guideforthepiston, and also permits one sideot the circuit to be grounded therethrough. The described construction provides ample guiding and centering means for both of the springs-29 and 30, preventing buckling and deformation of the latter holding one s'irin entirel se arate from a l s .V P the Otl161SP1lI1g, and insuring their proper and eiiicient' action. The metal shell 15 with 2 its relatively thick rear wall 16 and annular the shell) bent extension 20 thereof: affords a wide boss 17 affords a substantial guide and support; for the stem of the sliding contact member; also a liberal area for electrical contact between the current (grounded to and'thesliding stem; the laterally --contact head for'co operation with a plurality" of contact; strips; and, finally, the

offset extension met the slidingcontact rmemben being guided in the grooveor slot .18 holds the contact head 20 strongly against any lateral swinging movement, thus insuring the reciprocation of the sliding contact memberalways in the same plane, and also within the holding piston turning. In many constructions, the ribbon strips 23 and 24 are replaced by small round w1res,-;and where this is done, thedescribed construction at: fords room for a, considerable number of such narrow contacts side by side." The'described construction effectively eliminates all liability to stick because of friction and lost motion; and the counter-boring of the piston allows a maximum length forthe firsttouch spring with aminimuin. space, while the second-touch spring isenclosed' within the same brass shell and supported laterally by the latter. By having; both springs contained within the circumference of the pistoii, it is possibleto use closer centers, when assembling several ofthese piston switches in one bar or strip. Furthermore, both springs are easily accessible from the front by merely unscrewing the piston 25- from the stem 19. I I 3 Although I have shown and described my invention as embodied ina piston switch-tor" organs, and contemplate ,that'such willvbe 7 its principal use, it is manifest that the prin-:

ciple of theinvention may findembodi-ment in circuit controllingswitches'of thistype forotlier purposes and in other relations. i

Hence the invention is not limited'to its application' and use to and ,on organs, nor'to the precise details ofstruct-ureand arrangementshown, but maybe modified and varied purview'and scope of the appended claims.

I claim 1. In a piston switch of the character described, the combinationwith a. support, of

a metal shell of uniform internal diameter mounted therein, a circuit line connected to said shell, a piston slidablv fitting within projecting through said shell and having a laterally extending head, a fixed contact member mounted on said support and cooperating with said head, a spring in said shell normally holding said contact members separated, and means for preventing saidfirst-named contact member y from turning on its longitudinal axis. v

3. In a pistonswitch of the character described, the combination with a support, of

a cylindrical metal shell of uniform internal" r a fixed contact member mounted on said support and co-operating with said firstnamed contact member, a circuit line connected to said shell and to said fixed contact member, and a compression spring in said shell encirclingsaid first-named contact .member between the inner end of said shell and said piston for forcing the latter outwardly and thereby maintaining said contact members separated.

4. In a piston switch of the character described, the combination with a support, of a cylindrical metal shell of uniform internal diameter mounted therein, a circuit line connected to said shell, a piston slidably fitting within and guided throughout substantially its entire length by said shell, a contact member comprising'a stem portion attached to said piston and extending through the rear end of said shell and a laterally extended head portion, a fixed contact member mounted on said support and co-op-erating with. the head portion of said first-named contact member, a spring in said shell for forcing said piston outwardly and separating said contact members, and co-operating guides on said support and said first-named contact member operating to maintain the latter against turning on its longitudinal ax1s. 1

5. In a piston switch of the character described, the combination of a cylindrical metal shell of. uniform internal diameter having a'centrally apertured'rear end wall, a piston slidably fitting within and guided throughout substantially its entire length by said shell and counter-bored at its inner end to provide a spring supporting chamber, a contact rod attached to said piston and extending through said chamber and the aperture of said end wall, and a coil compression spring encircling said contact rod and supported atits outer end in said piston chamber and abutting at its inner end against said end wall.

6. In a piston switch of'the character describe-d, the combination of a cylindrical metal shell having a centrally apertured rear end wall formed with a central annular boss on its inner side, a piston slidably fitting said shell and centrally counter-bored at its inner end to provide a spring supporting chamber, a contact rod attached to said piston and extending through: said chamber and said annular boss and end wall, a first touch coil spring encircling said contact rod and supported at its outer end in said piston chamber and at its inner end centered on said boss, and a second-touch shorter compression spring encircling said first-named spring and reacting against the inner annular end of said piston during the last portion of the inward movement of the latter.

7. In a piston of the character described, the combination of a support formed with a transverse socket and a transverse groove at i one side of said socket, a cylindrical shell mounted in said socket, a piston slidably fitting said shell, a contact member attached to said piston, said contact member having a stem portion extending through the rear end of said shell, a laterally extending head portion, and a guide portion continuous with said head portion and slidably engaged with said groove, and a spring Within said. shell reacting against said piston.

8. In a piston switch of the character described, the combination of a support formed with atransverse socket and a transverse groove at one side of said socket, a cylindrical shell mounted in said socket, a piston slidably fitting said shell, a contact member attached to said piston, said contact member having a stem portion extending through the rear end of said shell, a laterally extending head portion, and a guide portion continuous with said head portion and slidably engaged with said groove, a plurality of leaf spring contact members attached to said support and overhanging the head portion of said movable contact member, and a spring within said shell reacting against said piston.

V GEORGE H. CHAPMAN.

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