US3165944A - Switch operating device - Google Patents

Description

Jan. 19, 1965 D. J. ARNEBERG 3,165,944

SWITCH OPERATING DEVICE 3 Sheets-Sheet l Filed March 23, 1961 y BY H62 ,q

Jan. 19, 1965 D. J. ARNEBERG 3,165,944

SWITCH OPERATING DEVICE Filed March 23, 1961 3 Sheets-Sheet 2 v W /Z\ {Z0- /y/ S 45 ZI ZZ 7 l Lia I' Ill4f INVENTOR. D/V J.' HFA/55596 Jan. 19, 1965 D. J. ARNEBERG 3,165,944

SWITCH OPERATING DEVICE Filed March 25, 1961 .'S Sheets-Sheet 3 All f7 IN VEN TOR.

United States Patent fri Y 3,165,944 SWITCH GPERATNG DEWCE Don J. Arneberg, Milwaukee, Wis., assigner to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed Mar. 23, 1961, Ser. No. 97,831 3 Claims. (Cl. 7e-527) This invention relates to switch operating devices for enclosures for electrical equipment, and particularly to devices which are exposed for manual operation on the exteriors of enclosures of the explosion resistant type.

Such enclosures are designed to withstand the force of explositions occuring therein as the result of ignition of explosive gases by sparking or arcing of the contained electrical equipment, and to prevent the ignition of explosive lvapors in the surrounding atmosphere by contact therewith of tlashes of vapor, sparks, and arcs escaping from Within the enclosures.

This requires not only the sealing of the main access opening through which the equipment may be installed in the enclosure, but also auxiliary passages through which access is afforded for making mechanical connections of external operating parts of switch operating devices with the enclosure. Further, the extraneous operating devices themselves also must be such as to prevent the escape therethrough or sparks, flashes, gases, or explosive vapors within the enclosures.

The present invention is an operating device for operating a switch used in connection with the equipment in such an enclosure, the device being arranged so that it can readily be installed in an auxiliary passage in the wall of the enclosure and connected to an electrical switch to operate the switch for controlling the equipment within the enclosure.

One of the principal objects of the invention is to provide a device which, when installed, assures a flame retardant path between the mounting of the device and the auxiliary passage in which it is installed, and between the externally exposed operating stem of the device and the parts of the device on the interior of the enclosure.

Another object is to provide a device of this character in which the operative switch is carried by the device itself and in which the cam for operating the switch is arranged so that it has no axial forces` imposed on it by axial movement of the operating stem or other parts of the device.

More specically, the device is one which, when mounted in the auxiliary passage in the enclosure, can be operated from the outside by a stem which is threadably connected to the supporting body of the device so as to form an effective rlame retardant path and thereby prevent the escape of flaming gases from within the enclosure between the stem and its supporting portion of the body, and in which the axial movement of the stem, as a result of `its threaded engagement with the body, is isolated completely from the rotational movement it imparts to the cam which operates the switch.

Another object is to provide a device of this character employing a rotatable stem and an intermedia-te member rotatable thereby, together with yieldable shock absorbing means arranged to return the stem and connected parts to neutral position.

Another object is to provide a device of this character which can be converted readily from a two-position startstop switch to a multi-position selector switch.

Various other objects and advantages will become apparent from the following description wherein reference is made to the drawings, in which:

FG. 1 is a top plan view of the device of the present invention, shown installed in upright position in a tragment of a top wall of an enclosure;

alessia Patented dan. i9., 1955 FIG. 2 is an enlarged front elevation of the device shown in FIG. l, part of the enclosure wall being shown in section for clearness in illustration;

FIG. 3 is a top plan View of the preferred embodiment of the device, with the operating handle removed from the stem;

FIG. 4 is a vertical sectional View taken on theline 4-4 in FG. 3, with the operating handle attached;

FIGS. 5 and 6 are cross sectional views taken on the lines 5- and 6 6, respectively, of FIG. 4;

FIG. 7 is a bottoni plan View of the device, with the switch removed, and is taken on the line 7-'7 ot FIG. 4;

FlGS. 8 and 9 are a front elevation and a top plan view, respectively, of a modied intermediate member which may be used in the device; and

FIGS. l() and ll are a front elevation and a bottomV plan view, respectively, of a niodicd positioning cani complementary to, and cooperable with, the intermediate member illustrated in FlGS. 8 and 9.

Referring to the drawings, the device is shown as installed in a top Wall W of an explosion resistant enclosure E, a por-tion only of which is illustrated. All of the device except the operating handle and mounting therefor is located within the enclosure. The device, indicated generally at 1, comprises a body 2 having at one end a bore 3 and a coaxial counterbore 4, and at the other end a bore 5 coaxial with the bores 3 and d. Mounted on the body is a cover'plate 6 which closes the end of the bore 3 and to which a connecting sleeve '7 is lixedly connected in sealed relation. The sleeve 7 is threaded both internally and externally, the external threading being complementary to the internal threading in an auxiliary passage 8 in the wall W. The sleeve 7 thus connects the body 2 to the wall W with a joint which prevents the escape of any ilaming gases, arcs, and sparks between the wall of the pas-sage 8 and the exterior or" the sleeve 7. In order to prevent accidental rotation of the sleeve 7 and consequently loosening of the connection between it and the body, the outer end portion 9 of the sleeve is machined chordally to provide inset parallel locking faces ld, the sleeve is screwed into the wall W preferably a distance such that the faces lli are exposed outwardly of the outer surface of the wall W a sufficient distance to receive a locking plate lll. The plate l1 is provided with a slot 12, the sides of which snugly engage the faces lll. The plate itself is secured to the wall W by a suitable screw or bolt 13 which prevents the plate from sliding endwise of the slot out of disengagement with the faces 1.0. Since the shoulders are parallel and linear, the plate cannot be slid off or rotated about the axis of the sleeve 7. The sleeve 7 is thus held in xed non-rotative position.

As mentioned, the sleeve 7 is internally threaded. A stern l5 having a threaded portion 16 complementary to, and in threaded engagement with, the internal threads of the sleeve 7, is provided. The tit between the threaded portion 16 and the internal threads of the sleeve 7 is such as to prevent ingress and egress of llaming vapors, arcs,

and flashes through the space between the sleeve and stem.

The stem 1S has an outer handle receiving portion 17 on which a handle 13 is secured for rotation with the stem. At its inner end, the stern has an out-of-round coupling lug 19 which, in the form illustrated, is square in cross section. Mounted `within the bores 3 and 4 in the body 2, for rotation relative to the body about the i .stem axis, is an intermediate member 2). The member 2li has an annular shoulder 2l which is arranged to engage a partition wall 22 in the body between the bores 4 and 5 so as to constrain the intermediate member 2li from movement relative to the body in a direction axially of the stem away from the neck. Since the threaded con- 'js a nection is required between the portion 15 of the stem l5 and the sleeve 7 to assure a proper seal, the stem 15 of necessity travels axiaily` when rotated, the amount of travel depending upon the pitch of the threads of the portion to.

In order to isolate the axial movement of the stem from the intermediate member 2t), the intermediate memer is provided with a socket 23 at the end adjacent the stern. The socket 23 is open endwise of the member and receives the lug t9 of the stern 15' with operating clearance. The shoulder Z1 restrains the intermediate member 249 from movement endwise away from the sleeve 7, and, accordingly, the stem l rotates the intermediate member 2% by the ing i9 while the stem moves axially relative to the intermediate member 2Q. Thus the axial movement of the stem is not transferred to the member 2G.

The intermediate member 29 isV provided at its periphery with a pair of longitudinal notches 26 which are arranged diametrically opposite each other and open radially outwardly. Mounted within the body are pairs ot spring strips, such as strips 27 and 23, arranged one pair for each notch. Each inner strip 23 has a portion bent inwardly toward the axis of the cam to provide a bulge Z9, or notch engaging means, complementary to its associated notch 2f. The bulges and notches have sloping side walls so that, with the yieldable pressure holding the bulges in the notches, each bulge can be dislodged by increasing the turning moment imposed by the stern on the intermediate member rl`his particular intermediate member Z@ is one used for devices of the momentary contact type.

The intermediate member 2t? has a cylindrical shank 3) which extends into a suitable complementary coaxial bore in the wall 22 and thus positions the cam in coaxial relation with the stem and vsupports it for rotation about the stem axis. The intermediate member 2d has a lug 31 which extends from the shank 3S into the bore 5 wherein a switch operating cam 32 for the switch is mounted. The cam 32 is in coaxial relation with the stem and intermediate member 2t) and is rotatable therewith about their common axis.

The lug 31 is out-of-round and, in the form illustrated, is square in cross section.

The switch operating cam 32 comprises a sleeve portion 33 having a radial flange 34 at its upper end. The cam has a socket 35 coaxia with the earns for receiving, and fitting with operating clearance, the lug 31. The cam 32 is mounted in the bore S with the upper face of the ilange 34 bearing against the under face of the partition wall 22. With this arrangement, no axial movement of the stem toward the -bore 5 can be transmitted to the cam 32. Thus the cam 32 is constrained from movement toward the stem by the wall 22, but is tree to move in the opposite direction.

A switch, indicated generally at 36, is secured to the underside or the body by suitable bolts 37 which extend into bores 38 at the underside of the body. The switch is drawn firmly against the bottom part of the body and forms a partial closure for the open end of the bore 5.

The switch 36 may be of a conventional type. In the form illustrated, in which the device is used for merely starting and stopping, Iis a two push button switch employing push buttons 4i) and 4l for controlling theoperation of the switch. These push buttons me normmly urged outwardly toward the cam 32 by springs within the switch. The cam 32 has a bottom cam surface 42 which is best illustrated in FIG. 7. It is arranged to depress one of the buttons ist) and 431 while releasing the other and to reverse the operation. As mentioned, however, the specific type of switch is secondary'.

In order to bring the parts to a neutral position, as shown in FIG. 5, a torsion spring 45 is provided. The

torsion spring is rotatably mounted on suitable sleeves 45 on the exterior of the intermediate member 29. Se-

Gil

cured in the intermediate member 20 is a pin 47 which extends downwardly past the spring in a direction endwise of the intermediate member Z9. The free ends of the spring, indicated at 45S and 49, extend radially outwardly to engage opposite sides of the pin 47. The pin increases the torsion of the spring as it is pushed lirmly against one free end, by rotation of the positioning intermediate member Zt, while the other free end is held in fixed position circumferentially of the axis ot" the intermediate member 2t?.

The body 2 is provided, in the bore 4, with a rigid abutment 59 which also passes between the free ends of the spring. Thus, upon rotation of the intermediate memmer 2@ in one direction, one free end engages one side of the pin and the other free end engages the abutment Si?, the two being so positioned that continued rotation tends to increase the torsion of the spring, thus increasing the resistance lto rotation. The abutment 5l) and the pin 47 are so positioned that the torsion spring tends to bring the cam to rest with the notches 25 in position for engagement by the bulges 29.

rlShe rotation of the intermediate member 29 in either direction is limited by stops S1 formed on the interior walls of the counterbore d. These stops are engaged by pin 47. It is apparent that rotational movement of the handle l in either direction from its neutral position will cause a considerable amount of energy to be stored in the torsion spring. Thus when the handle 18 is moved and held so the pin t7 is juxtaposed to one of the stops 51 with the cam 34 actuating plunger 49 of switch 36E, then if the handle 13 is suddenly released, the energy stored in the torsion spring could cause the parts ot the device to rotate past the neutral position to a position wherein the cam 31 could cause the plunger 4l to be momentarily actuated. The bulges 2.9 which cooperate with the notches 26 prevent this result. When the torsion spring moves the parts of the device toward the neutral position, the bulges 29, or notch engaging means, engage the notches 26 and prevent further rotational movement of the .intermediate member 29 by the torsion spring.

Thus it will be seen that an eiliective ilame retarding path is provided between the stem 15 and the sleeve 7 by providing threads, and the axial travel resulting from the threads is compensated for by the connection of the lug 19 and socket 93, and the lug 3l and socket 35. Ot course, if desired, `these sockets and lug connections can be reversed, the lugs being placed on the cams and the sockets in the stem and lower end of the intermediate member 2G.

The arrangement described is preferred for it permits changing the switch readily from a momentary contact type start-stop switch to a maintained contact type multiposition switch. For this purpose, the intermediate member 2b, together with its torsion spring 4S, and supporting Steeve 46, is removed and an intermediate member 52, such as illustrated in FIGS. 8 and 9, is substituted. The spring and sleeves are omitted when using the intermediate member 52. The difference in the intermediate member :72 is that instead of two notches, such as at 26 in the intermediate member 2i?, a plurality of notches, sp a c-ed at dicerent distances circumterentially of the intermediate member, are provided; for example, for a three position switch, three sets of notches 53, 54, and 55. Instead of the operating cam 32, an operating cam 5'7 is provided. The cam 57 is the same as the cam 32, except for the configuration of its bottom surface d2. The cam 57 has cam faces 55 arranged to that they can give three settings of the switch, the effective conguration depending upon the type of switch. By these simple changes, therefore, the switch operating mechanism heretofore described can be converted lfrom a two-way momentary start and stop switch into a three-way maintained Contact positional switch. If desired, of course, additional positions in excess of three may be provided merely by changing the operating cam and the intermediate member. Having thus described my invention, I claim:

1. A switch operating device for explosion resistant enclosures for electrical equipment and comprising a body, a stationary member on the body having an internally threaded bore, an externally threaded stem member coaxial with said bore and in threaded engagement with the threads thereof and suiliciently close fitting to substantially prevent passage of gases between the stem member and stationary member, whereby upon rotation oi the stem member, the stem member moves axially relative to the body, a rotatable cam member mounted in the body in coaxial relation to the stem member for rotation, relative to the body, with the stem member and constrained by the body from movement relative to the body in a direction endwise ofthe body toward the stationary member eyond a predetermined spaced relation to the stationaryV member, an intermedate member rotatably mounted in the body between the stem member and cam member and supported by the body in coaxial relation to the stem member and in lixed position endwise of the body, first connecting means connecting the stem member and intermediate member for co-rotation, additional connecting means connecting the intermediate member and cam member for co-rotation, and said first connecting means aiording relative axial movement of the stem member and intermediate member while connecting them for corotation.

2. A device according to claim 1 wherein notch means and notch engaging means are provided, said two last means being carried, one by the intermediate member and the other by the body, and being movable relatively toward and away from each other, one of the last two mentioned means being spring seated relative to the other, and one of the last two mentioned means being carried by the intermediate member for yieldably constraining the intermediate member and body from rotation relative to each other when the two last mentioned means are interengaged.

3. A switch operating device comprising a body having coaxial bores extending inwardly from its ends, a partition wall between the bores, a cover on one end of the body, said cover having an internally threaded stationary sleeve coaxial with the bores, an externally threaded valve stem in threaded engagement with the sleeve and sufficiently close fitting to substantially prevent passage of gases between the stem and sleeve, said stem extending into the bore at one end of the body, a switch operating cam member in the bore at the opposite end of the body and rotatable about the bore axis and bearing at one end against said partition wall, an intermediate member in the bore at said one end of the body and mounted in said bore for rotation about the bore axis and having a bearing area exposed toward and bearing against said partition wall, one of said members in one bore having a projection at one end extending through said partition wall into the t bore at the opposite side of the wall, the other member having a socket coaxial with the bores and accommodating said projection, said projection and socket connecting the members for co-rotation and relative axial movement, said intermediate member and said stem having a socket and lug connection at their adjacent ends and connecting the stem and intermediate member for co-rotation and relative axial movement,rnotch means, complementary notch engaging means, said two last means being carried, one by the intermediate member and the other by the body, and being movable relatively toward andaway from each other into and out of interengagement with each other, one of the last two mentioned means being spring seated relative to the other, and one of the last two mentioned means being carried by the intermediate member for yieldably constraining the intermediate member and body from rotation relative to each other when the two last mentioned means are interengaged.

References Cited in the file of this patent UNITED STATES PATENTS 1,605,457 Muend Nov. 2, 1926 2,240,922 Bissell May 6, 1941 2,257,033 Bissell Sept. 23, 1941 2,473,081 Vaughan June 14, 1949 2,680,971 Kreiner June 15, 1954 2,810,435 Demi et al. Oct. 22, 1957 2,861,470 Baker Nov. 25, 1958 2,878,334 Aller Mar. 17, V1959 2,886,675 Berry Mayk 12, 1959 FOREIGN PATENTS 1,105,385 France June 29, 1955 1,074,702 Germany Feb. 4, 1960

Claims (1)

1. A SWITCH OPERATING DEVICE FOR EXPLOSION RESISTANT ENCLOSURES FOR ELECTRICAL EQUIPMENT AND COMPRISING A BODY, A STATIONARY MEMBER ON THE BODY HAVING AN INTERNALLY THREADED BORE, AN EXTERNALLY THREADED STEM MEMBER COAXIAL WITH SAID BORE AND IN THREADED ENGAGEMENT WITH THE THREADS THEREOF AND SUFFICIENTLY CLOSE FITTING TO SUBSTANTIALLY PREVENT PASSAGE OF GASES BETWEEN THE STEM MEMBER AND STATIONARY MEMBER, WHEREBY UPON ROTATION OF THE STEM MEMBER, THE STEM MEMBER MOVES AXIALLY RELATIVE TO THE BODY, A ROTATABLE CAM MEMBER MOUNTED IN THE BODY IN COAXIAL RELATION TO THE STEM MEMBER FOR ROTATION, RELATIVE TO THE BODY, WITH THE STEM MEMBER AND CONSTRAINED BY THE BODY FROM MOVEMENT RELATIVE TO THE BODY IN A DIRECTION ENDWISE OF THE BODY TOWARD THE STATIONARY MEMBER BEYOND A PREDETERMINED SPACED RELATION TO THE STATIONARY MEMBER, AN INTERMEDIATE MEMBER ROTATABLY MOUNTED IN

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