US3144530A - Re-settable switch device - Google Patents

Description

1964 I c. BlLY ETAL 3,144,530

I RE-SETTABLE SWITCH DEVICE Filed July 18, 1962 2 Sheets-Sheet 1 Aug. 11, 1964 c. BILY ETAL 3,144,530

RE-SETTABLE SWITCH DEVICE Filed July 18, 1962 2 Sheets-Sheet 2 United States Patent 3,144,530 RE-SETTABLE SWITCH DEVEQE Clement Billy, Paris, and Jean Lescarhoura, Nanterre, France, assignors to La Telemecauique Electrique, Nanterre, France, a company of France Filed .luly 18, 1962, Ser. No. 210,647 Claims priority, application France Aug. 11, 1961 13 Claims. (Cl. 230-76) This invention relates to re-settable safety switch devices of the type having one or more electric switch contacts which are adapted to be moved from a normal to a safety position on movement of a monitor member from a normal to an emergency position, and which then require the manual operation of a resetting control to be effected in order to restore the switches to their normal condition.

As one example of such re-settable switch devices, there may be mentioned the devices of this type that are used to monitor the movement of a heavy mechanical contrivance such as an elevator cage, part of a hoisting apparatus, or the like. Should such a contrivance accidentally move beyond one of the prescribed limits of its travel, resulting in a'potentially dangerous condition, the contrivance acts on a monitor member in the form of a rotatable lever arm which operates the safety switch device to deenergize an electric motor powering the contrivance, ap ply brakes, and/or effect any other desired safety function. After the dangerous condition has been removed due to the contrivance being returned to within its normal range of movement, it is then necessary to actuate a manual resetting control, e.g. push-button, of the switch device, in order to restore the switching means to their normal condition, such as the motor-energizing condition.

In prior safety switch devices of this general type, means were usually provided whereby movement of the monitor member from normal to emergency position would act on the switching means with a snap-action ensuring highly rapid movement of the contacts to their emergency condition (usually the open condition of the switch contacts). However, the manual resetting means were not usually adapted for exerting a comparably quick switch operating action, and this was a serious defect in view of the high current loads frequently involved. It is, accordingly, an object of this invention to provide a re-settable safety switch device embodying improved snapaction means operative to move the switch contacts with extreme rapidity both to their emergency, and to their normal, circuit conditions.

Further objects of the invention are to provide resettable switch devices of much greater compacity and smaller weight than those heretofore available, and having a number of further advantages including simplicity, ruggedness, improved protection against dirt and damage from the surrounding medium, and ease of fabrication under mass production conditions.

In accordance with a chief aspect of the invention, there is provided a re-settable safety switch device comprising a monitor member capable of assuming a normal and an emergency position, switching means, an actuating rod connected with the switching means and displace able axially between a first and a second positions in which the switching means are in a normal and an emergency circuit conditions respectively, camming means movable with the monitor member and engageable with one end of the rod for initiating rod displacement from the first to the second position on movement of the member to its emergency position, a manual re-setting control engageable with the opposite end of the rod for initiating rod displacement from the second towards the first position, and a spring arrangement associated with the rod and 3,144,530 Patented Aug. 11, 1964 having an unstable intermediate position whereby axial displacement of the rod in either direction from one of its end positions past said unstable intermediate position will snap the rod forcefully to its opposite end position, the camming means preventing rod displacement by said control past its unstable intermediate position and towards its first position when the monitor member is in its emergency position.

An exemplary embodiment of the invention will now be described for illustrative purposes with reference to the accompanying drawings, wherein:

FIG. 1 is a front view of the sealed switch casing.

FIG. 2 is a section on line 11-11 of FIG. 1.

FIGS. 30: and 3b are sections on line IIIIII of FIG. 1 respectively in the reset and in the disengaged conditions of the switch device; and

FIG. 4 is an axial sectional view of an improved resetting push-button on an enlarged scale.

The embodiment shown comprises a casing in two parts 1 and 2 assembled by means of screws 3 on opposite sides of an intervening seal 4. The casing part 1 is provided with holes 5 serving to mount the assembly by means of bolts 6 from a supporting structure, e.g. through intermediate brackets 7. The bottom of the casing part 2 is formed with spaced apertures provided with sealing fittings 8 through which conductor cables are passed into and out of the casing for connection e.g. with a motor to be controlled by the device. In the top of casing part 2 there is provided a bearing 2a (see e.g. FIG. 3b) for a vertical pivot shaft 9 having a cam disc 11) secured on its lower end within the casing and an arm 11 secured to its upper end outside the casing.

The cam disc 10 is secured to shaft 9 by a screw 12. Before positioning shaft 9 in its bearing, a seal ring 13 is engaged around the shaft from its reduced-diameter end so as to seat against a shoulder 9a provided at the upper end of the shaft. A key 14 received in a slot in the upper end of shaft serves to secure the seal ring 13 to the shaft for bodily rotation. A bent strip 15 is secured by screws 16 against the seal ring 13 and the upper end of shaft 9 so as to connect lever arm 11 rigidly with shaft 9, whereby rotation of the lever arm 11 about the axis of the shaft will rotate the cam disc 10.

Cam disc 10 (also see FIG. 1) is formed with a recess 10a milled in one side of it. It is further formed with a cylindrical hole 1%, and is provided with a pair of angularly spaced projecting fingers 10c serving to limit the rotation of the cam disc. A spring 19 received in a re cess of the casing part 1 acts on a detent ball 17 to urge the latter into the hole 10b and latch the cam disc resiliently in a predetermined angular position.

Secured in the casing part 2 by means of screws 21 engaging spacer posts depending from the top of the casing part 2 is a platen 24) which supports the switch assembly presently described. Secured to the under side of platen 20 by way of screws 24 and spacer posts 22 is a cross member 23. Member 23 and platen 20 are centrally formed with aligned holes of square contour through which a rod 25 of complementary form slidably extends. Notches 25a formed in opposite sides of the rod 25 a short distance from platen 2t serve to attach the ends of flexible leaf springs 26 having their free ends engaged in similar notches 22a formed in the posts 22.

The leaf springs 26 are mounted in a flexed condition so that when notches 25a are positioned substantially opposite to the notches 22a, the rod 25 is axially positioned in an unstable condition; the leaf springs 26 are then buckled or flexed a maximum amount, so that they will tend to shift the rod 25 to either one of two stable end positions, the upper position shown in FIG. 3a near the cam disc 10, or the lower position shown in FIG. 3b near the bottom of the casing. A re-setting push-button 3 27, presently described in detail, is mounted in a side of the casing part 1 and serves to initiate the shifting of rod 25 towards its upper position.

The rod 25 has secured to its upper end, directed toward the cam disc (also see FIG. 2) a cross member 23, and to its lower end directed towards push-button 27 a cross member 29. A pair of switch housings 39 are mounted in casing 12 on opposite sides of rod 25; a base end of each housing 30 engages a complementary aperture formed in the platen 2 and is secured thereto by a screw 31. Within each housing 39 there is sridably mounted an insulating rod 32 of square cross section having one end projecting toward cross member 28 and its opposite end toward cross member 29.

Each insulating rod 32 is formed with transverse openings in which contact strips 33 are slidable, being pressed into engagement with side walls of the related openings by compression springs 34 mounted therein. The strips 33 cooperate at their ends with stationary contact segments (not shown) provided within each of the switch housings 30 connected with outlet terminals 35 of the housings 36. The contacts provided by strips 33 and the fixed contact elements are closed when the actuator rod 25 is in the retracted position shown in FIG. 3a as will be presently explained.

Each of the insulating rods 32 is shorter than the distance between the cross members 28 and 29. Compression springs 36 interposed between cross member 29 and flanges 37 secured to the rods 32 urge said rods towards the cross member 28. Conversely, springs 3 interposed between the end walls of the switch housings 3i) and surfaces of the rods 32 urge the rods towards the cross member 29. Thus the rods 32 are at all times resiliently urged in one or theother axial direction so that one end of the rod engages one of the cross members 28 or 29 in each of the end positions of the actuator rod 25.

Details of switch housings such as 30 have been described in Patent No. 2,929,899. Moreover, arc blow-out means are preferably provided between the contact strips 33 and related fixed contact elements as described in Patent No. 2,995,638.

The re-setting push-button 27 is of a sealed construction, as shown in FIG. 4, and comprises a generally cylindrical moulding 39 of rubber-like material over which a rigid cap 49 is fitted. The rubber moulding is formed with a peripheral skirt 39a of V section formed with a flange which engages the walls of an opening 42 formed in the casing part 1 and is secured thereto by means of an annular insert 41 adhesively bonded in place. The annular insert 41 includes a cylindrical portion overlying the inner wall of skirt 39a in the opening 42 so as to prevent damage to the skirt. The V-shaped contour of the skirt 3% urges the button 27 to the depressed position shown in FIG. 4-, fiush with the ring insert 41, so that the projecting position of the button is not a stable position. Since the pushbutton is thus at all times urged to its retracted position within the casing, it tends at all times to remain in engagement with the end of the rod 25 in the reset position of the device, and the ring insert 41 prevents removal or separation of the rod from outside the casing 12 of the apparatus.

The apparatus operates as follows:

In the operative or normal position shown in FIG. 1, the lever arm 11 is normal to the longer sides of the rectangular contour of casing 1-2, and projects into the path of the movable member to be monitored. The arm 11 is held in this position by the detent ball 17 cooperating with aperture 10b. In this position, the camming recess 19a registers with the actuator rod 25, so that depression of re-setting button 27 will retract the rod 25 until a nut 43 mounted on the inner end of the rod and serving to secure the cross member 28 to it, is received in the recess 1011. This position of the actuator rod is retained owing to the over-centre action of the leaf springs 26. The force exerted by the leaf springs on the rod 25 also holds the contacts including strips 33 in closed condition, with the contact pressure being determined by the compression of springs 34. In this condition of the apparatus there is established a current path through the contact strips 33 and fixed contact elements to energize the motor moving the member being monitored.

Should the movable member accidentally move past the limits of its normal travel so as to engage the monitor arm 11, the arm 11 is rotated to its emergency position, rotating cam disc 10 so that the walls of cavity 1011 cam the nut 43 and rod 25 in the rightward axial direction of FIG. 2, whereupon the leaf springs 26 are urged towards their unstable intermediate position. The depth of recess 10a is such that the springs reach said unstable position before the nut 43 has quite emerged from out of the recess, so that the springs 26 snap over-centre and propel the rod 25 forcefully towards its projected position, in which movement the rod 25 carries the contact strips 33 in a direction to cutoff the motor supply.

The rotational displacement of lever arm 11 required to eifect the action described in small, say of the order of 10, and is limited in ei her direction by engagement of the stop fingers 16c with inner Wall surfaces of casing part 1. The afore-mentioned displacement of rod 25 has resulted in moving push-button 27 to its projected position (FIG. 3b), so that the disengaged condition of the apparatus is rendered apparent, and to enhance the visibility the outer edge surface of cap 40 is desirably made to be of a contrasting colour. As will be seen from FIG. 3!), it is impossible to actuate the re-setting button 27 to restore the rod 25 to its normal position unless the moving member which has rocked the arm 11 has itself been restored to a normal position, permitting the arm to be manually returned to the position in which the recess 10a is registering with not 43.

Otherwise the end of the nut engages the flat face of disc 10, so that the spring plates 26 are unable to flex sufficiently on depression of push-button 27 to move to and past their unstable center position and thus carry the rod 25 to its initial end position.

When however the arm 11 has been repositioned manually as just mentioned, depression of push-button 27 will move the springs 26 past their intermediate position, whereupon the springs will snap over to their oppositely flexed, alternative stable end position carrying with them the actuator rod 25 and insulating rods 32, and causing a rapid and sudden closure of the contacts associated with the strips 33.

It will thus be seen that rapid contact closing and opening actions are obtained with the device described, provided that one of the cross members 28 or 29 will only engage the insulating rods 32 to start displacing them after the displacement of actuator rod 25, which has been initiated in the corresponding direction, is sufficient to bring said actuator rod 25 past the position of unstable centre equilibrium of the leaf springs 26. If this unstable position is at the mid-point of the total displacement of actuator rod 25, the desired result will be obtained if the displacement of rods 32 is only one half the displacement of actuator rod 25, with the lost motion connection between actuator rod 25 and rods 32 also being equal in magnitude to one half the displacement of actuator rod 25.

In the embodiment illustrated, the length of displacement of actuator rod 25 is limited on one side by engagement of cross member 28 with platen 20 and on the other side by engagement of cross member 29 with the switch housings 30 containing the movable contact strips. The length of insulating rods 32 therefore is equal to the spacing between the cross members 28 and 29 minus one half the displacement of actuating rod 25.

An equivalent result may be obtained according to the invention by providing actuator rod 25 with a finger engaging in an elongated aperture formed in insulator rod 32 so as to provide an amount of lost motion for d the finger, longitudinally of actuator rod 25, corresponding to one half the displacement of rod 25.

The construction of push-button 27, the seal 4 and the ribs or flanges 13a in the insulating ring member 13 cooperating with grooves in the bearing 2a contribute to provide an efiective protection of the apparatus against the ingress of dirt and moisture.

It should be understood that various modifications may be made in the single illustrative embodiment of the invention shown and described without exceeding the scope of the invention.

What we claim is:

1. A re-settable switch device comprising a frame, a monitor member pivotally carried by said frame and capable of assuming a normal position and an emergency position, switching means secured to said frame, an actuating rod connected with the switching means and displaceable axially in said frame between a first position and a second position in which positions the switching means are in a normal circuit condition and an emergency circuit condition respectively, camming means fast with said monitor member and engageable with one end of the rod for initiating rod displacement from the first to the second position on movement of the monitor member to its emergency position, a manual resetting control carried by said frame and engageable with the opposite end of the rod for initiating rod displacement from the second towards the first position, and a spring arrangement bearing against said frame, having a pivotal engagement with said rod and imposing, on said rod, a force perpendicular thereto in an unstable intermediate position of said rod, whereby axial displacement of the rod in either direction from one of its end positions past said unstable intermediate position will snap the rod forcefully to its opposite end position, the camming means preventing rod displacement by said control past its unstable intermediate position and towards its first position when the monitor member is in its emergency position.

2. A device according to claim 1, wherein the camming means comprises a disc-like part rotatable with the monitor member about an axis parallel to the rod.

3. A device according to claim 2, wherein said disclike part is formed with a camming recess greater in depth than about one half the total displacement of the rod and adapted to be moved into alignment with the rod on the monitor member assuming its normal position.

4. A device according to claim 3, wherein resilient latching means are provided for holding the cam disc in at least one of its normal and emergency positions.

5. A device according to claim 1, wherein the spring arrangement comprises a pair of flexed leaf springs on opposite sides of the rod and having their inner ends engaged in the rod and their outer ends engaged with said frame.

6. A re-settable switch device according to claim 1, wherein said switching means comprise a movable contact-holder displaceable a limited distance relatively to said actuator rod, and parallel thereto, between contactclosing and -opening positions.

7. A device according to claim 6, wherein said limited distance is substantially equal to one half the total axial displacement of the actuator rod between its end positions.

8. A device according to claim 1, wherein said switching means comprise a movable contact holder displaceable a limited distance relative to said rod and parallel thereto between contact-making and -braking positions, and opposing spring means urging said movable contactholder to an intermediate position relative to said rod.

9. A device according to claim 8, including a fixed switch housing having fixed contact means therein and wherein said movable contact holder is slidably displaceable in said fixed switch housing between said positions.

10. A device according to claim 1, wherein said switching means comprise a pair of fixed switch housing extending parallel to and spaced from said actuator rod on opposite sides thereof, fixed contact means in said housings, a pair of movable contact-holder rods supported from said actuator rod for sliding displacement in said respective housings between contact-making and -breaking positions relative to said fixed contacts, and opposing spring means urging said contact holders to intermediate positions relative to said rod.

11. A device according to claim 10, wherein said pushbutton comprises a cylindrical body and a peripheral annular cylindrical flange connected integrally with said body by a V-shaped connecting portion projecting towards the interior of the casing, said cylindrical flange having an end portion engaging said casing aperture, and means securing said flange in said aperture.

12. A device according to claim 1, wherein the resetting contrcl comprises a push-button of moulded elas tomer material mounted in an aperture of the casing of the device in alignment with the related end of the actuator rod and adapted to be urged by its inherent elasticity to a retracted position with its outer end surface substantially flush with the casing wall.

13. A device according to claim 11, wherein said securing means comprise an annular insert engageable with the inner periphery of said flange within the aperture.

No references cited.

UNITED STATES PATENT erricn CERTIFICATE OF QORRECTION Patent No, 3, 144 530 August 11 1964 Clment Bily et a1.

, It is hereby certified that error appears in the above numbered patent ,reqliring correction and that the said Letters Patent should read as corrected below.

Column 6 line 48 for the claim reference numeral "11" read 12 Signed and sealed this 29th day of December 1964.

(SEAL) Attest:

W. SWIDER EDWARD J. BRENNER Aj testing Officer Commissioner of Patents

Claims (1)

1. A RE-SETTABLE SWITCH DEVICE COMPRISING A FRAME, A MONITOR MEMBER PIVOTALLY CARRIED BY SAID FRAME AND CAPABLE OF ASSUMING A NORMAL POSITION AND AN EMERGENCY POSITION, SWITCHING MEANS SECURED TO SAID FRAME, AN ACTUATING ROD CONNECTED WITH THE SWICHINGMEANS AND DISPLACEABLE AXIALLY IN SAID FRAME BETWEEN A FIRST POSITION AND A SECOND POSITION IN WHICH POSITIONS THE SWITCHING MEANS ARE IN A NORMAL CIRCUIT CONDITION AND AN EMERGENCY CIRCUIT CONDITION RESPECTIVELY, CAMMING MEANS FAST WITH SAID MONITOR MEMBER AND ENGAGEABLE WITH ONE END OF THE ROD FOR INITIATING ROD DISPLACEMENT FROM THE FIRST TO THE SECOND POSITION ON MOVEMENT OF THE MONITOR MEMBER TO ITS EMERGENCY POSITION, A MANUAL RESETTING CONTROL CARRIED BY SAID FRAME AND ENGAGEABLE WITH THE OPPOSITE END OF THE ROD FOR INITIATING ROD DISPLACEMENT FROM THE SECOND TOWARDS THE FIRST POSITION, AND A SPRING ARRANGEMENT BEARING AGAINST SAID FRAME, HAVING A PIVOTAL ENGAGEMENT WITH SAID ROD AND IMPOSING, ON SAID ROD, A FORCE PERPENDICULAR THERETO IN AN UNSTABLE INTERMEDIATE POSITION OF SAID ROD, WHEREBY AXIAL DISPLACEMENT OF THE ROD IN EITHER DIRECTION FROM ONE OF ITS END POSITIONS PAST SAID UNSTABLE INTERMEDIATE POSITION WILL SNAP THE ROD FORCEFULLY TO ITS OPPOSITE END POSITION, THE CAMMING MEANS PREVENTING ROD DISPLACEMENT BY SAID CONTROL PAST ITS UNSTABLE INTERMEDIATE POSITION AND TOWARDS ITS FIRST POSITION WHEN THE MONITOR MEMBER IS IN ITS EMERGENCY POSITION.

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