US3777084A

US3777084A - Safety switch with sealable cover and interlock means for preventing operation of sealing means when cover is fully open

Info

Publication number: US3777084A
Application number: US00290691A
Authority: US
Inventors: T Rys
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1972-09-20
Filing date: 1972-09-20
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04
Also published as: CA992595A

Abstract

A safety switch having a reciprocable cover sealing cam member operable by a cover sealing handle and having first interlock means preventing movement of the switch blade operating handle and switch blades to ON position when the cover is open or is closed but not sealed. A second interlock means is provided preventing operation of the cover sealing handle and cam member when the cover is open, thereby preventing defeat of the first interlock means by manipulation of the cover sealing handle.

Description

United States Patent H91 Rys Dec. 4, 1973 [54] SAFETY SWITCH WITH SEALABLE COVER 3,678,230 7/1972 Rys 200/50 A AND INTERLOCK MEANS FOR 3,629,536 12/1971 Rys..... 3,381,106 4/1968 Rys 200/168 G PREVENTING OPERATION OF SEALING MEANS WHEN COVER IS FULLY OPEN Inventor: Tadeusz J. Rys, Monroe, Ohio Assignee: Square D. Company, Park Ridge, Ill.

Filed: Sept. 20, 1972 Appl. No.: 290,691

US. Cl 200/50 A Int. Cl. I-I0lh 9/22 Field of Search 200/50 A, 168 G,

200/172 R, 172 A, 168 R References Cited UNITED STATES PATENTS 4/1968 Rys 200/168 G Primary Examiner-J. R. Scott Attorneyl-larold J. Rathbun et al.

[57] ABSTRACT A safety switch having a reciprocable cover sealing cam member operable by a cover sealing handle and having first interlock means preventing movement of the switch blade operating handle and switch blades to ON position when the cover is open or is closed but not sealed. A second interlock means is provided preventing operation of the cover sealing handle and cam member when the cover is open, thereby preventing defeat of the first interlock means by manipulation of the cover sealing handle.

5 Claims, 7 Drawing Figures PNENTEU DEC 4 I975 SHEET 10F 3 FIG. 2

PAIENTEDBEB 4191s SHEET 3 [IF 3 FIG. 7

SAFETY SWITCH WITH SEALABLE COVER AND INTERLOCK MEANS FOR PREVENTING OPERATION OF SEALING MEANS WHEN COVER IS FULLY OPEN Certain industrial environments require safety switch enclosures which can be sealed against dust andabrasive particles. A gasket may be provided on the inside ofa flanged cover, and to make sure the switch is sealed, it'has been the practice to provide interlock means preventing movement of the switch blade operating handle to ON position until the cover is drawn up tight, to'compress the'gasketagainst the edges of the box, by operation of a cover sealing handle and cam member. Operation of thecover sealing handle, when the cover is closedbut'not sealed, seals the cover and also overcomes the interlock means, enabling the switch blade operating handle to be-turnedto ON position. Normally the cover sealing handle'is not operated when the cover is open. In prior switches, an element of danger was still present, however, because it was possible to deliberately operate the cover 'sealinghandle and cam with the cover fully open and thereby overcome the interlock means and enable the switch blade operating handle to' be moved to ON'position with-the cover open.

An object of this invention is to provide a safety switch having a second interlock means which prevents operation of a cover sealing handle when the cover is open far enough to escape the cover sealing cam, thereby preventing defeat of a first interlock means which interferes with movement of a switch blade'operating handle to ON position when-the cover is open.

Other objects and advantages will appear whenthe following description is considered along with the accompanying drawings in which:

FIG. 1 is a right-handsideelevational view of a safety constructed in accordance-with the invention, a switch blade operating handle being in OFF position and a cover sealing handle being in a non-sealing position;

FIG. 2 is a view of a reciprocable cover sealing cam member by itself as it would appear in the switch looking in the direction of arrows 2-2 of FIG. 1;

FIG. 3 is a sectional view of the switch of FIG. I looking at the inner side of the right-hand side wall of the box of the switch, the switch blade operating handle being in OFF position, the cover sealing handle being in a non-sealing position, and the cover (not shown) being in open-position;

FIG. 4 is a fragmentary sectional view similar to FIG. 3, but with the cover in closed, unsealed position;

FIG. 5 is a fragmentary view of the inside of the cover taken along line 5-5 of FIG. 4 and showing a releasable latch member for the cover sealing cam member;

FIG. 6 is a sectional view similar to FIG. 4, but with the cover sealed; and

FIG. 7 is a sectional view similar to FIG. 6, but with the switch blade operating handle in ON position.

With respect to the drawings, a switch '12 constructed in accordance with the invention is shownin FIG. land includes a box 13 and a flanged cover 14 pivotally mounted on a left-hand side wall (not shown) of' the box in a conventional manner. A pin 'l5'pivotally to the side wall 13a by a pair of rivets 19. The operating handle 16 and locking plate 18 are better shown and described in copending application, Ser. No. 229,896,

filed Feb. 28, 1972, and assigned to the assignee of this application.

A pin 20 pivotally mounted in the side wall 130 serves as a mounting for a cover sealing handle 21. FIG. 1 also shows a slotted pin 22'mounted in the side wall 13a and rotatable to release the cover 1 for opening when the cover sealing handle 21 is in non-sealing position and the operating handle 16 is in an ON position. A tubular collar 24 on the cover 14 shields another slotted pin 25 as best shown in FIG. 4, the pin 25 being rotatable to release-a cover sealing cam member 26 (FIGS. 2, 3, 4, 6 and 7) for return to a non-sealing position as hereinafter described.

As'more fully shown and described in the aforementioned copending application, the operating handle 16 is operatively connected to a generally U-shaped switch blade drive bar 27 (FIGS. 3, 4, 6 and 7) having one of its mounting leg portions pivotally mounted on the pin 15. An end portion of the pin 15 opposite the end mounted in the side wall 13a is pivotally mounted in a bracket 28 secured'to an inner surface of the side wall 13a. A first actuating member (not shown) is fixedly mounted on the pin 15 and provided with a lost-motion connection to a second actuating member 30 pivotally mounted on the pin 15 and driven during the latter portion of its pivotal movement to either of two extreme positions by a drive pin 31 mounted in one end portion of each of apair of drive links 32, only one of which is visible in FIGS. 3, 4, 6 and 7. The ends of the drive links 32 opposite the drive pin 31 are reciprocally mounted in one leg'portion of an L-shaped bracket 34 having its other leg portion pivotally mounted on a pin 35 secured in the side wall 13a. A compression spring 36 is mounted on the drive links 32 and seated at one end on a collar 37 also mounted on the drive links 32' and at the other end on the leg portion of the bracket 34 in which the drive links 32 are reciprocally mounted. The leg portion of the drive bar 27 mounted on the pin 15 extends through a slot in an offsetting portion of the actuating member 30 offsetting a portion 30a thereof from the remaining portion mounted on the pin 15.

An inner end portion of the pin 22 is pivotally mounted in the bracket 28. As more fully shown and described in the aforementioned copending application, an interlock member 39 is fixedly mounted on the pin 22 and cooperates both with the actuating member '30 and with an L-shaped bracket 40 secured to the inside of the cover 14. When the cover 14 is open, or closed but not sealed, and an attempt is made to move the operating handle 16 to ON position, a portion (not shown) of the interlock member 39 blocks movement of the actuating member 30. When the operating handle 16 is in ON position and the cover 14 is closed but unsealed, and an attempt is made to open the cover,.the interlock member 39 blocks movement of the bracket "40. A knowledgeable person can defeat these interlocks by turni'ngthe pin 22 with a tool such as a screwdriver.

mounted in a right-hand side wall 13a of the" box'serves which is visible and the other of which extends through a slot 18a in an 'offsethandle locking plate 18' secured The cover sealingcam member 26 is best shown in FIGS. 2 and 3 and includes an elongated flat body portion 26a provided with three

elongated slots

26b, 26c, and '26d'through which three rivets 42, 43 and 44 respectively extend. The rivets are secured in the side wall 13a and the member 26 is thus reciprocably mounted on the inner side of the side wall 130. Offset from the body portion 26a, as best shown in FIG. 2, are a pair of projecting cam portions 262 and 26f disposed adjacent opposite ends of the body portion 26a but pointing in the same direction, toward a top wall 13b (FIGS. 3, 6, and 7) of the box. The

cam portions

26e and 26f are insertable in suitable apertures (not shown), provided respectively in a pair of brackets 46 and 47 secured to the cover 14, to seal the cover by compressing gasket material 48 glued to the inside of the cover against the edges of the box 13. The member 26 is movable to cover sealing position by an actuating member or crank 50 fixedly mounted on an inner end portion of the pin 20 and operatively connected to the member 26 by a bent tang 50a received in a suitably aperture 263. A compression spring 52 mounted on a tongue portion 26h (FIG. 2) of the member 26 and a tongue portion 28a of the bracket 28 continuously biases the member 26 toward unsealing position.

When the cover sealing cam member 26 is moved to sealing position by manipulation of the cover sealing handle 21, it is latched in the sealing position against the force of the spring 52 by a releasable latch member 54 (FIG. pivotally mounted on a pin 55 disposed in a bracket 56 secured to the inside of the cover 14. Pivotal movement of the latch member 54 is limited in opposite directions by a pair of

bent tongue portions

56a and 56b of the bracket 56, the tongue portion 56a being L-shaped and having a leg portion 56c disposed in overlapping relationship with the latch member 54 to serve as a retainer and guide therefor. The latch member 54 is biased toward the tongue portion 56b and toward latching relationship with the member 26 by a compression spring 58 seated at one end on a tongue portion 54a of the latch member and at the other end on a bent tongue portion 56d of the bracket. As hereinbefore mentioned, the member 26 is releasable from latched relationship by rotation of the slotted pin 25 (FIG. 4). An actuating member or crank 60 fixedly mounted on an inner end portion of the pin 25 is provided with a bent tang 60a received in a suitable aperture 54b in the latching member.

As the cover sealing cam member 26 is moved toward sealing position, a bent tang portion 26] thereof moves the interlock member 39 out of interfering relationship with the actuating member 30. The operating handle 16 and switch blade drive bar 27 can then be moved to ON position. Prior to my invention it was possible to move the member 26 to sealing position by manipulation of the handle 21 even though the cover 14 was open, thereby defeating the first interlock means by moving the interlock member 39 out of interfering relationship with the actuating member 30 and allowing the handle 16 to be moved to ON position with the cover 14 open.

In accordance with my invention, I have provided a second interlock means to prevent defeat of the first interlock means, the second interlock means comprising a tang position 26k provided on the member 26 and coooperable with the pivotable L-shaped bracket 34, which acts as a releasable latch. When the cover 14 is open as in FIG. 3, and an attempt is made to move the member 26 to sealing position by manipulation of the handle 21, the leg portion of the L-shaped bracket 34 through which the drive links 32 extend will obstruct the path of the tang position 26k and prevent further movement of the member 26. The restricted amount of movement of the member 26 is insufficient to move the interlock member 39 out of interfering relationship with the actuating member 30, and thus the handle 16 can not be moved to ON position. However, when the cover 14 is closed, a generally L-shaped bracket 61 secured to the inside of the cover pivots the bracket 34 out of the path of the tang portion 26k, as shown in FIG. 4, enabling the member 26 to be moved to scaling position, as shown in FIG. 6, and enabling the tang portion 26j to move the interlock member 39 out of interfering relationship with the actuating member 30. The handle 16 can then be moved to ON position, as shown in FIG. 7.

Various modifications may be made in the structure shown and described without departing from the spirit and scope of the invention.

I claim:

1. In a safety switch having an open-front box with side walls, a switch blade operating handle pivotally mounted on one side wall of the box, a cover pivotally mounted on an opposite side wall of the box, a cover sealing handle pivotally mounted on the one side wall, switch blade drive bar pivotally mounted in the box and operable by the switch blade operating handle, a cover sealing cam member reciprocally mounted on an inner side of the one side wall and operable by the cover sealing handle, means on the cover engageable by the cover sealing cam member to seal the cover to the box, and interlock means preventing movement of the switch blade operating handle to an ON position when the cover is open and also when the cover is closed but not sealed, the interlock means being moved out of interfering relationship with operation of the switch blade operating handle by movement of the cover sealing cam member to a cover sealing position, the improvement comprising second interlock means preventing movement of the cover sealing cam member to the cover sealing position within the box when the cover is open.

2. A safety switch as claimed in claim 1 including means on the cover moving the second interlock means out of interfering relationship with movement of the cover sealing cam member when the cover is moved to closed position.

3. A safety switch as claimed in claim 1 including an actuating member operatively connected to the switch blade drive bar and having a lost motion connection to the switch blade operating handle, a bracket pivotally mounted on the inner side of the one side wall, a drive link reciprocally mounted adjacent one end in the bracket and operatively connected adjacent an oppositeend to the actuating member, and a compression spring mounted on the drive link, and wherein the second interlock means comprises the bracket.

4. A safety switch as claimed in claim 3 including means on the cover moving the bracket out of interfering relationship with movement of the cover sealing cam member when the cover is moved to closed position.

5. A safety switch as claimed in claim 1 including a releasable latch member pivotally mounted on an inner side of the cover and releasably latching the cover sealing cam member in sealing position when the cover is sealed to the box.

Claims

3. A safety switch as claimed in claim 1 including an actuating member operatively connected to the switch blade drive bar and having a lost motion connection to the switch blade operating handle, a bracket pivotally mounted on the inner side of the one side wall, a drive link reciprocally mounted adjacent one end in the bracket and operatively connected adjacent an opposite end to the actuating member, and a compression spring mounted on the drive link, and wherein the second interlock means comprises the bracket.