US3212346A

US3212346A - Switch operating device

Info

Publication number: US3212346A
Application number: US131778A
Authority: US
Inventors: Bachman Anatole
Original assignee: Amalgamated Electric Corp Ltd
Current assignee: Amalgamated Electric Corp Ltd
Priority date: 1961-08-16
Filing date: 1961-08-16
Publication date: 1965-10-19
Anticipated expiration: 1982-10-19

Description

Oct. 19, 1965 A. BACHMAN SWITCH OPERATING DEVICE 3 Sheets$heet 2 Filed Aug. 16, 1961 Inventor Attorney Oct. 19, 1965 A. BACHMAN SWITCH OPERATING DEVICE 3 Sheets-Sheet 5 CONTACT CLOSED 4.95F)

CONTACT SLIDING CONTACT PARTED fit 470A! gay WV F l G. 4 Inventor Attorney Filed Aug. 16, 1961 3,212,346 SWITCH OPERATING DEVICE Anatole Bachman, Willowdale, Qntario, Canada, assignor to Amalgamated Electric Corporation, Limited, Toronto, Ontario, Canada Filed Aug. 16, 1961, Ser. No. 131,778 8 Claims. (Cl. 74-100) This invention relates to a device for operating a single electric switch or a plurality of electric switches. More particularly, this invention relates to a switch operating device constructed so as to provide a large force on the movable contact making and breaking member of a switch when a large force is required, i.e., at the time when it is desired to break the electrical contact.

It will be appreciated by those skilled in the art that an efficient switch, from the electrical point of view, is one with a minimum amount of electrical energy loss (1 R) which appears in the form of heat. In order to minimize 1 R loss it is essential that the movable and fixed contacts of a switch firmly engage one another. However, when firm engagement between the contact members is made, another problem arises, especially with larger switches, this problem being the large force which must be applied to the movable contact member to disengage it from the fixed contact member.

Accordingly, it is an important object of my invention to provide a switch operating device constructed such that the force acting on the movable contact member to disengage it from the fixed member is much greater than that applied by the person opening the switch at the crank arm of the switch.

It is well known that electrical switches, especially of the higher rated type, should be designed so that as soon as the movable and fixed contact members disengage they are withdrawn from one another quickly. The reason for this, of course, is to minimize arcing.

Accordingly, it is a further object of my invention to provide a switch operating device constructed such that the contacts disengage and part from one another quickly.

Yet another object of my invention is to provide a new and improved switch operating device which operates with a snap action.

In accordance with my invention I provide a switch operating device constructed such that a larger force is applied to the movable contact member thereof to Open the switch than is applied by the person opening the switch to the crank arm of the switch, this force decreasing in magnitude as the movable contact member slides towards the open position of the switch. At the same time, the speed with which the movable and fixed contact members separate increases as the contact members separate. Just at the point where the contact members separate, a snap-action is effected.

In brief, an operating device embodying my invention is adapted for use with a switch of the type having a movable contact making and breaking member. The device comprises lug means adapted to engage and move the movable contact making and breaking member from one position to another position, whereby the switch may be opened or closed. A first link member is pivotally connected to the lug means and is adapted to move the lug means from the one position to the other position. A second link member is pivotally connected to the first link member at a pivot point, the pivot point being con- 3,2 i 2,346 Patented Oct. 19, 1965 Other objects and advantages of a device embodying my invention will become apparent from the following detailed description taken in conjunction with the drawings in which:

FIGURE 1 illustrates in perspective one embodiment of my invention;

FIGURE 2 is a top elevation of the device shown in FIGURE 1, with the switch removed;

FIGURE 3 is a graph depicting the operation of a device embodying my invention without snap-acting means; and

FIGURE 4 is a schematic representation of the device shown in FIGURE 2, the forces acting on the device be ing shown as vectors.

Referring now to the drawings, in particular FIGURES 1 and 2, for a more detailed description of a switch operating device embodying my invention, I have shown a switch operating device generally designated as 10. This device includes a base 11 having three

straight slots

12, 13 and 14 and a slot 15 in the form of a segment of a circle therein. Mounted on one side of base 11 is a switch 16, only the contact bridging member 16' thereof being shown. Switch 16 may be of the type described in United States Patent 3,087,039 dated April 23, 1963.

Contact bridging member 16' comprises a pair of spaced apart

side frame members

17 and 18 made of any suitable electrical insulating material.

Frame members

17 and 18 are secured together at the rear thereof by a U- shaped channel member 19. Supported between the front ends of

side frame members

17 and 18 are

electrical contacts

20, 21, 22 and 23, contact 20 being electrically connected to contact 22 and contact 21 being electrically connected to contact 23. Contact

receiving spaces

24 and 25 are provided between

contact arms

20 and 21 and contact arm-s 22 and 23 respectively, these contact receiving spaces being adapted to receive and connect line and load blade members (not shown) respectively. For a more complete description of switch 16 and contact bridging member 16; reference is made to my aforementioned copending application.

Positioned on top of base 11 is lug means 26, log means 26 comprising a plate 27 and

trip members

28, 29 and 30 afiixed to and upstanding from the plate. Each of

trip members

28, 29 and 30 have U-shaped notches therein for engaging channels 19 in contact bridging members 16', it being understood that with the embodiment of my invention shown in FIGURE 1 three switches 16 may be operated in gang fashion, although only one switch has been shown for the sake of simplicity. Plate 27 and

trip members

28, 29 and 30 are adapted to be slid back and forth in

slots

12, 13 and 14 in base 11 by means which will be hereinafter described. It will be noted that plate 27 is provided with guide members 28' and 30' which extend into and engage

slots

13 and 14 respectively. Positioned at one side of switch operating device 10 is a manually actua'ble handle 31.

Referring now to FIGURE 2, handle 31 is connected to a lost motion device, generally designated 32, positioned on the other side of base 11. Lost motion device 32 includes a lever 33 and a pair of fingers 34 and 35. Fingers 34 and 35 are adapted to engage and rotate crank arm 45. Lost motion device 32 is rotatably mounted on base 11 about an axis at 36 and is provided with a pair of spaced apart

notches

37 and 38 and abutments 37' I and 38'. Stop means 39 project downwardly from base 11 and engage notch 37 and abutment 37' when lost motion device 32 is in the position shown in FIGURE 2. When the lost motion device is rotated in the direction indicated by the arrow, stop means 39 eventually will engage notch 38 and abutment 38. Thus it will be seen that stop means 39 prevents lost motion device 32 from executing a complete rotation. r

Pivotally connected to lever 33 at 40 is a snap actlng means generally designated 41. Snap acting means 41 comprises a rod 42 pivotally connected to lever 33 as aforementioned at 40 and which passes through a hearing 43 and is slidable therein. Bearing 43 is pivotally connected to base 11 so as to permit rod 42 to swing when. lost motion device 32 rotates. A spring 44 is provided and strongly urges rod 42 against lost motion device 32, whereby the tendency is for rod 42 and lever 33 to remain misaligned with respect to one another.

A link member or crank arm 45 is rotatably mounted on base 11 about axis 36. It should be noted, however, that crank arm 45 is rotata-bly mounted at 36 independent of lost motion device 32. The opposite end of crank arm 45 is pivotally connected at 46 to a ling member 47, the other end of which is pivotally connected at 48 to a link member 49. It will be noted from FIGURES l and 2 that pivot point 48 is constrained to move in a circular path, this path being defined by the side walls of slot 15. It should be noted, however, that pivot point 48 may be constrained to move in a circular path by connecting a link member (not shown) to pivot point 48 and pivotally connecting the other end of the link member to base 11 at the point which is the centre of curvature of circular slot 15,in which case circular slot 15 is not required. Link 49 is pivotally connected at 50 to lug means 26 by means of a pivotal connection between link 49 and plate 27, this pivotal connection extending through slot 12. An important feature of this invention which is shown in FIGURES 2 and 4 is that pivot 50 and the centre of curvature of slot 15 are both on the straight line in which pivot 50 is constrained to move by slot 12. Also, as shown in FIGURES 2 and 4, the left-hand terminus of the circular arc in which pivot 48 is constrained to move preferably is on this same straight line.

Certain features of the operation of a switch operating device embodying my invention are best shown by considering that snap acting means 41 are deleted, and hence it will be assumed in the following discussion that this is the case. In the position of the device shown in FIGURES 1 and 2, the switch 16 is closed, contact

arms

20 and 21 engaging a line blade member (not shown) and contact

arms

22 and 23 engaging a load blade member (not shown), an electrical path then being established between the line and load blade members through

contact arms

20, 21, 22 and 23. In order to open the switch, lug means 26 must be actuated downwardly in FIGURE 2 and backwardly in FIGURE 1. This is accomplished by rotating handle 31 in the direction shown by the arrow. As handle 31 is rotated, a predetermined degree of rotation of lost motion device 32 takes place before finger 34 engages crank arm 45. The purpose of this lost motion will be discussed in detail at a later point. When finger 34 engages crank arm 45, the crank arm is rotated to the right in FIGURE 2, and pivot point 46 travels in a circular path. Link 47 is drawn to the right, and pivot 48 is constrained to travel in a circular path by virtue of the engagement between pivot point 48 and the side walls of slot 15. Link 49 is drawn downwardly and to the right in FIGURE 2, and hence lug means 26 is drawn downwardly, the lug means travelling .in a straight path in

slots

12, 13 and 14. When lost motion device 32 has been rotated sufficiently far that stop means 39 engages notch 38 and abutment 38' and prevents further rotation of lost motion device 32, lug means 26 will have moved from one end of

slots

12, 13 and 14 to the other end, and switches 16 will be opened by virtue of the fact that

trips

28, 29. and 30 engage channels 19 and carry contact bridging members 16' to the open position of the switches.

Those skilled in the art will appreciate that in order to open a switch of the type which has a movable contact member firmly engaging a fixed contact member, it is necessary to apply a large force to the movable contact tact bridging member 16'.

member. In accordance with my invention, my device is constructed in such a manner that the portion of the force which a person applies to handle 31 and which appears at crank arm 45 is considerably less than the force which is applied to lug means 26 in order to move con- In other words, the former force is multiplied by my device. This is best shown in FIGURES 3 and 4. In FIGURE 4 I have shown for three positions of link member 45 the forces and their components acting at various points of my device. These vectors are drawn assuming a constant force F acting at pivot point 46 tangential to the circular are described by pivot point 46 as crank arm 45 rotates. At the 0 position of crank arm 45 force F is resolved into two components, one passing through

points

46 and 48, and the other passing through

points

46 and 36. The former component is transferred to point 48 and is resolved into two components, one passing through

points

48 and 50 and one passing through point 48 and the centre of curvature of slot 15. The former component is transferred to point 50 and is resolved into two components, one the force F acting parallel to

slots

12, 13 and 14 and the other being perpendicular thereto. A vector force dia gram also is shown for the 15 and the 45 position of crank arm 45. It will be noted that the force F acting at pivot point 50 and pulling on contact bridging member 16' is substantially greater than force F. Referring to FIGURE 3, which is a graph showing the pulling force F acting on lug means 26 at 50 plotted against the angular movement of crank arm 45 with constant force F, with an embodiment of my invention which has been constructed and successfully operated, I have been able to provide an initial force F acting at point 50 which is 5 times as large as the force F acting at point 46. As crank arm 45 is rotated through an arc of 15, force F acting at point 50 decreases as shown in FIGURE 3, until, at the point where the fixed and movable contacts of the switch are just parting, the force is 1.5 times the force F at point 46. Thus it will be seen that a device embodying my invention applies a large force to the movable contact bridging member of a switch when such a large force is required, i.e., when it is desired to open the switch. As crank arm 45 is rotated by finger 34 through the next 30 of arc, the force F drops to less than the force F, but by the time that force F is less than force F, the movable and fixed contacts are well separated from one another,

Those skilled in the art will appreciate that, neglecting losses, the work done at any point such as 50 must be equal to the amount of input work. Thus it will be appreciated that the curve showing the acceleration of point 50 plotted against constant angular movement of crank arm 45 with constant force F will be the opposite of the curve shown in FIGURE 3, and that point 50 will have zero acceleration when crank arm 45 is at the zero degree position, this acceleration increasing exponentially as the crank arm is moved through 45. Thus, with a device embodying my invention, fast acceleration is provided as the contacts are part-ing. This, of course, is desirable in order to inhibit arcing.

The purpose of snap acting means 41 is to coact with crank arm 45 through lever 33 and finger 34 to procure a snap action thereof which then is transmitted through links 47 and 49 to impart snap action to lug means 26. It will be seen from FIGURE 2 that as handle 31 is rotated, lever 33 rotates and rod 42 swings to the right and slides downwardly in bearing '43. At the same time, spring 44 is compressed and urges rod 42 upwardly against lever 33, so that rod 42 and lever 33 always tend to be forced into misalignment with one another. Eventually, through movement of handle 31 and consequent movement of lever 33, rod 42 and lever 33 will become aligned with one another, and the slightest amount of continued rotation of handle 31. will cause spring 44 to expand, forcing rod 42 against lever 33 and causing lost motion device 32 to quickly snap to the position where stop means 39 engages notch 38 and abutment 38'. This snap action occurs just as the movable and fixed contact members of switches 16 are separating from one another, and results in the movable contact members being quickly withdrawn from the region of the fixed contact members. The sequence of operations is such that starting with the handle 31 in the position shown in FIGURE 2, as the handle is rotated, spring 44 is cocked. Continued rota tion of handle 31 causes finger 34 to engage crank arm 45, and this crank arm is moved through 15 from the position shown in FIGURE 2, at which point the contacts just are beginning to part and snap action takes effect. In order to reset the device when it is in the position with stop means 39 engaging abutment 38, handle 31 is rotated counterclockwise, causing finger 35 to engage and rotate crank arm 45. Snap action is achieved just as the contact members of the switch are meeting and assists in providing a large force to cause contact engagement.

It will be seen from the foregoing, neglecting, for the moment, the snap-acting effect of snap-acting means 41, that a switch operating device embodying my invention provides a large force and a low acceleration on the movable contact bridging member of a switch just when such conditions are needed, i.e., when the movable and fixed contacts are being disengaged to open the switch or engaged to close the switch. In addition, my switch operating device is constructed such that increasing acceleration is applied to the movable contact member of the switch as it separates from the fixed contact member, as is desired to inhibit arcing. The snap-acting means 41 provides an even greater acceleration during this latter interval, and also serves to increase the force applied to the movable contact member just when it is about to engage the fixed contact member.

While I have described certain preferred embodiments of my invention, it will be appreciated to those skilled in the art that numerous modifications and changes may be made therein Without departing from the spirit and scope of my invention as defined in the appended claims.

What I claim as my invention is:

1. An operating device for a switch of the type having a movable contact making and breaking member, said device comprising lug means adapted to engage and move said movable contact making and breaking member from one position to another position, whereby said switch may be opened or closed, a first link member, pivot means pivotally connecting said first link member and said lug means, said first link member being adapted to move said lug means from said one position to said other position, said pivot means being constrained to move in a straight line during movement of said lug means from said one position to said other position, a second link member pivotally connected to said first link member at a pivot point, said pivot point being constrained to move in a circular are, said pivot means, the centre of curvature of said circular arc and one terminus of said circular arc lying on said straight line, and a third link member pivotally connected to said second link member, said third link member being adapted to be rotated about an axis, a lost motion device, said lost motion device being adapted to be independently rotated about said axis and including a lever and finger means, said finger means being adapted to engage said third link member and rotate said third link member about said axis after a predetermined degree of rotation of said lost motion device, and snap acting means pivotally connected to said lever and co-acting with said third link member through said lever and said finger means to procure snap-action of said third link member after a predetermined degree of rotation of said third link member,

2. An operating device according to claim 1 wherein said finger means are a pair of fingers, one of said pair of fingers being adapted to engage said third link member and rotate said third link member about said axis after a predetermined degree of rotation of said lost motion device in one direction, the other of said finger means being adapted to engage said third link member and rotate said third link member about said axis after a predetermined degree of rotation of said lost motion device in the other direction.

3. An operating device according to claim 2 including stop means engaging said lost motion device and permitting said lost motion device to execute only part of a c0mplete rotation.

4. An operating device for a switch of the type having a movable contact making and breaking member, said device comprising lug means adapted to engage and move said movable contact making and breaking member from one position to another position, whereby said switch may be opened or closed, a first l-ink member, pivot means pivotally connecting said first link member and said lug means, said first link member being adapted to move said lug means from said one position to said other position, said pivot means being constrained to move in a straight line during movement of said lug means from said one position to said other position, a second link member pivotally connected to said first link member at a pivot point, said pivot point being constrained to move in a circular arc, said pivot means, the centre of curvature of said circular arc and one terminus of said circular arc lying on said straight line, and a third link member pivotally connected to said second link member, said third link member being adapted to be rotated about an axis, a lost motion device, said lost motion device being adapted to be independently rotated about said axis and including a lever and finger means, said finger means being adapted to engage said third link member and rotate said third link member about said axis after a predetermined degree of rotation of said lost motion device, and snap-acting means co-acting with said third link member through said lever and said finger means to procure snap-action of said third link member after a predetermined degree of rotation of said third link member, said snap acting means comprising a rod pivotally connected to said lever, a bearing within which said rod is axially slidable, said bearing being pivotally mounted to permit swinging of said rod as said lever rotates, and a spring urging said rod into misalignment with said lever.

5. An operating device according to claim 4 including stop means engaging said lost motion device and permitting said lost motion device to execute only part of a complete rotation.

6. An operating device according to claim 5 including a pair of spaced-apart abutments on said lost motion device, said stop means being adapted to engage said abutments.

7. An operating device for a switch of the type having a movable contact making and breaking member, said device comprising a base having a straight slot and providing a support for said switch upon one of its sides, lug means having at least a portion thereof located upon said one side of said base and adapted to engage and move said movable contact making and breaking member from one position to another position, whereby said switch may be opened or closed, a first link member mounted on the other side of said base, pivot means pivotally connecting said first link member and said lug means, said first link member being adapted to move said lug means in said slot from said one position to said other position, said pivot means being constrained to move in a straight line during movement of said lug means from said one position to said other position, a second link member mounted on said other side of said base and pivotally connected to said first link member at a pivot point, said pivot point being constrained to move in a circular arc, said pivot means, the centre of curvature of said circular arc and one terminus of said circular are lying on said straight line, and a third link member mounted on said other side of said base and pivotally connected to said second link member, said third member being rotatably mounted on 7 said base about an axis, a lost motion device mounted on said other side of said base, said lost motion device being independently rotatably mounted on said base about said axis and including a lever and finger means, said finger means being adapted to engage said third link member and rotate said third link member about said axis after a predetermined degree of rotation of said lost motion device, and snap acting means mounted on said other side of said base, said snap-acting means co-acting with said third link member through said lever and said finger means to procure snap-action of said third link member after a predetermined degree of rotation of said third link member, said snap acting means comprising a rod pivotally connected to said lever, a bearing within which said rod is axially slida'ble, said bearing being pivotally mounted on said base to permit swinging of said rod as said lever rotates, and a spring urging said rod into misalignment with said lever.

8. An operating device according to claim 7 including 8 stop means engaging said lost motion device and permitting said lost motion device to execute only part of a complete rotation.

References Cited by the Examiner UNITED STATES PATENTS 659,946 2/00 Wittingham.

1,518,701 12/23 Penn.

2,442,464 6/48 Link 742 X 2,479,266 8/49 Rowe 7497 X 2,567,436 9/51 Lampe 74106 2,800,547 7/57 Johnson 74100 X FOREIGN PATENTS 178,667 10/35 Switzerland.

BROUGHTON G. DURHAM, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

Claims

1. AN OPERATING DEVICE FOR A SWITCH OF THE TYPE HAVING AA MOVABLE CONTACT MAKING AND BREAKING MEMBER, SAID DEVICE COMPRISING LUG MEANS ADAPTED TO ENGAGE AND MOVE SAID MOVABLE CONTACT MAKING AND BREAKING MEMBER FROM ONE POSITION TO ANOTHER POSITION, WHEREBY SAID SWITCH MAY BE OPENED OR CLOSED, A FIRST LINE MEMBER, PIVOT MEANS PIVOTALLY CONNECTING SAID FIRST LINK MEMBER AND SAID LUG MEANS, SAID FIRST LINK MEMBER BEING ADATED TO MOVE SAID LUG MEANS FROM SAID ONE POSITION TO SAID OTHER POSITION, SAID PIVOT MEANS BEING CONSTRAINED TO MOVE IN A STRAIGHT LINE DURING MOVEMENT OF SAID LUG MEANS FROM SAID ONE POSITION TO SAID OTHER POSITION, A SECOND LINK MEMBER PIVOTALLY CONNECTED TO SAID FIRST LINK MEMBER AT A PIVOT POINT, SAID PIVOT POINT BEING CONSTRAINED TO MOVE IN A CIRCULAR ARC, SAID PIVOT MEANS, THE CENTRE OF CURVATURE OF SAID CIRCULAR ARC AND ONE TERMINUS OF SAID CIRCULAR ARC LYING ON SAID STRAIGHT LINE, AND THIRD LINK MEMBER PIVITALLY CONNECTED TO SAID SECOND LINK MEMBER, SAID THIRD LINK MEMBER BEING ADAPTED TO BE ROTATED ABOUT AN AXIS, A LOST MOTION DEVICE, SAID LOST MOTION DEVICE BEING ADAPTED TO BE INDEPENDENTLY ROTATED ABOUT SAID AXIS AND INCLUDING A LEVER AND FINGER MEANS, SAID FINGER MEANS BEING ADAPTED TO ENGAGE SAID THIRD LINK MEMBER AND ROTATE SAID THIRD LINK MEMBER ABOUT SAID AXIS AFTER A PREDETERMINED DEGREE OF ROTATION OF SAID LOST MOTION DEVICE, AND SNAP ACTING MEANS PIVOTALLY CONNECTED TO SAID LEVER AND CO-ACTING WITH SAID THIRD LINK MEMBER THROUGH SAID LEVER AND SAID FINGER MEANS TO PROCURE SNAP-ACTION OF SAID THIRD LINK MEMBER AFTER A PREDETERMINED DEGREE OF ROTATION OF SAID THIRD LINK MEMBER.