US3768052A

US3768052A - Release device for electrical switches

Info

Publication number: US3768052A
Application number: US00240950A
Authority: US
Inventors: K Buhler; D Floessel
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Switzerland; BBC Brown Boveri France SA
Priority date: 1971-04-26
Filing date: 1972-04-04
Publication date: 1973-10-23
Anticipated expiration: 1990-10-23
Also published as: DE7119396U; CH530710A; IT953687B; DE2124608B2; FR2134431A1; DE2124608A1; NL7205550A; FR2134431B1; DE2124608C3; JPS5548418B1

Abstract

A device for initiating release of the contacts of an electrical switch includes an actuating rod which is tensioned in the upward, release direction, but which is retained in a downward position, until released, by means of a cylindric roll operating in an angular slot and which is maintained in a state of unstable equilibrium by the magnetic attractive force of a hold-release magnet. The angular slot and cylindric roll mechanism is so designed that when the release device is in its ''''hold'''' position, a releatively high tensional force exerted on the actuating rod tending to pull it upward is counter-balanced by a much smaller magnetic force.

Description

United States Patent [1 91 Biihler et a1.

RELEASE DEVICE FOR ELECTRICAL SWITCHES Inventors: Karl Biihler, Nussbaumen; Dieter Floessel, Fislisbach, both of Switzerland Aktiengesellschatt Brown, Boveri & Cie, Baden, Switzerland Filed: Apr. 4, 1972 Appl. No.: 240,950

Assignee:

Foreign Application Priority Data Apr. 26, 1971 Switzerland 6060/71 US. Cl. 335/190, 200/153 Int Cl. l-l0lh 3/42 Field of Search 335/190, 26'

References Cited UNITED STATES PATENTS 4/1966 Lindsay 335/190 1 Oct. 23, 1973 2,994,753 8/1961 Astleford, Jr. et a1 335/26 3,209,101 9/1965 Peek et a1. 335/190 3,602,676 8/1971 Mrenna et a1. 200/153 G Primary Examiner-Harold Broome Attorney-Ralph E. Parker et a1.

[57] ABSTRACT A device for initiating release of the contacts of an electrical switch includes an actuating rod which is tensioned in the upward, release direction, but which is retained in a downward position, until released, by I means of a cylindric roll operating in an angular slot and which is maintained in a state of unstable equilibrium by the magnetic attractive force of a hold-release magnet. The angular slot and cylindric roll mechanism is so designed that when the release device is in its hold position, a releatively high tensional force exerted on the actuating rod tending to pull it upward is counter-balanced by a much smaller magnetic force.

4 Claims, 4 Drawing Figures 1 RELEASE DEVICE FOR ELECTRICAL SWITCHES The present invention relates to an improved release device for initiating operation of the mechanism of an electric switch by means of which the contacts are actuated from a closed to an open position, or vice-versa.

In general, the release device includes a cylindric roll which performsa blocking function preventing actuation of the switch contacts until released, the roll being connected to a contact actuating component of the switch mechanism which is subjected to a tensional force, and being retained in an unstable state of rest by the attractive force of a magnet until released by a reduction in the magnetic holding force.

It is known from the prior art, e.g., Swiss patent No.

315,719, that periodically movable contact devices can be protected against interference from fault currents by means including a component subjected to the action of a spring which is supported with the assistance of a roll body and a thrust bearing. The roll body is retained in its blocked position by the armature of a magnet. The armature to be actuated is relative large and for this reason the release operation takes place with a considerable degree of inertia. Moreover, in this case, suspension of the tensioned component at the roll by means of an edge and cross beam arrangement is relatively complicated.

German patent application No. 1,119,982, now laid open for public inspection, discloses a release device for electrical, fast-action switches which includes a cylindric blocking roll retained in a labile, i.e., unstable position of rest by magnetic force when the switch is in its blocked position. In that application, the roll cylinder utilized in the blocking mechanism also functions as the armature of the holding magnet. This specific arrangement restricts selection of the material for the roll cylinder for two reasons, one being the necessity for keeping wear abrasion to a minimum and the other being the importance of its magnetic properties.

The object of the present invention is to provide an improved construction for a switch contact release device of the type generally described which is not only relatively simple and inexpensive to manufacture but which is fast-acting and wear-resistant.

In general the improved release device, includes a cylindric roll body connected to a contact actuating com ponent of the switch such as a vertically extending rod which is subjected to a tensional stress when the switch contacts are in a rest position, either closed or open, the rollbody operating within an angular slot and being maintained in a state of unstable equilibrium by the magnetic attractive force of a hold-release magnet. The angular slot and cylindric roll mechanism is so designed that when the release device is in its hold position, a relatively high tensional force exerted on the actuating rod tending to move it upward is counterbalanced by a relatively much smaller magnetic force. This is accomplished by a unique mechanical advantage achieved in the force train and particularly at the slot and cylindric roll components whereby the tensional force drawing upwardly on the actuating rod exerts only a relatively small horizontal break-a-way component at the armature of the hold-release magnet. However, as soon as the release takes place, the vertical component of the tensional force drawing the actuating rod upward increases rapidly with the result that the contacts of the switch are quickly actuated.

The foregoing as well as other objects and advantages inherent in the inventive concept will become more apparent from the following description of three different embodiments thereof and from the accompanying drawings wherein:

FIG. 1 is a vertical central sectional view of one embodiment of the release device with certain components shown in elevation;

FIG. 2 is a horizontal section taken on line A A of FIG. 1;

FIG. 3 is a vertical view showing a modified construction for the angular slot and cylindric roll components of the mechanism by which the desired initial mechanical advantage at the hold-release magnet is achieved; and

FIG. 4 is a view similar to FIG. 3 and illustrating another modified construction for the angular slot and cylindric roll components of the mechanism by which the desired result is achieved.

With reference now to the drawings and to FIGS. 1 and 2 in particular, the improved release device for initiating actuation of the contacts of an electrical switch in one direction or the other, to effect closure or opening of the contacts, includes a two-part housing" 1 bolted together and in which is mounted a hold-release magnet 2. Magnet 2 includes a pair of pole shoes 2a between which is seated an armature 3. The latter is normally retained in place against the pole shoes by the magnetic flux produced by the magnet. Accordingly, the magnet 2 can be of the elecrical type wherein a coil is provided to produce the magnetic flux which holds the armature in place, or preferably the magnet can be of the permanent type which produces its own magnetic flux, and a release coil can be wound onto the magnet structure which when energized will produce a demagnetizing magnetic flux that has a diretion opposite to that produced by the magnet, thus resulting in an overall weakening of the total magnetic flux acting to hold the armature in place against the pole shoes with the result that the armature is released when pulled in the break-a-way direction.

Armature 3 is displaceable parallel to itself in a horizontal direction within the housing 1 towards and away from the magnet pole shoes 2a by guideways la which receive opposite end portions of the armature, and a pair of rigid draw straps 4 are pivotally connected respectively at one end to opposite end portions of armature 3. The opposite ends of straps 4 are pivotally connected to and support for rotation stub shafts at the opposite ends of a cylindrical roll 5 which operates within a substantially L-shaped slot 9 provided in a guide plate 10 which is secured within housing 1 by means of bolts 11. As is seen in FIG. 1, the slotted plate 10 extends vertically and the lower part 9a of the guide slot 9 for roll 5 slopes slightly downward from the horizontal. The upper part 9b of the slot 9 extends vertically upward.

Pivotally connected to each end portion of roll 5 are the ends of a second pair of rigid draw straps 6, the opposite ends of these straps being articulated to the lower end 7a of an actuating rod 7 which extends in a vertically upward direction, the rod also being provided with a cylindric guide plate 71) slidable within an upwardly extending guide tube 8 having the lower end thereof secured to an upwardly extending tubular outlet lb of housing 1. As is evident from FIG. 1, the mechanism thus described operates between one limit position shown in solid lines, i.e., a hole position, wherein roll is located in the lower part 9a of slot 9 near the bend in the slot and armature 3 is engaged with the pole shoes 2a, to its other limit position depicted in dash-dot lines i.e., a release position wherein roll 5 has been shifted around the bend into and upward along the vertical part 9b of the slot, and armature 3 has been shifted to the left and thus disengaged from the pole shoes.

Rod 7 continues upward into other parts of the overall switch structure, not illustrated, and is continuously subjected to a tensional force in the upward direction when the mechanism is in the hold position. When rod 7 is released by release of the magnet armature 3, it movesupward and functions to effect actuation of the switch contacts from a closed to open position, or vice versa. This is commonly done by using rod 7 to control a blast valve which moves to an open position as soon as rod 7 is released, whereupon a pressurized gas is caused to flow to the switch contact chamber and to actuate a drive mechanism for the contacts, the blast valve being thereafter closed and causing rod 7 to be shifted downwardly by suitable. mechanism, e.g., a pneumatic piston, to the starting position whereby armature3 is shifted back into engagement with the pole shoes 2a, and'rod 7 is thereby held in the unstable downward position until it is once again desired to actuate the switch contacts. None of the above-referred to switch structure has been illustrated since it is well known and does not per se constitute part of the inventive concept.

The present invention resides in the novel interconnections between the magnet armature 3 and release rod 7 whereby a relatively great pulling (upward) force which exists on rod 7 is retained in balance, i.e., in a state of unstable equilibrium by use of a relatively small magnetic holding'force. This is due to the fact that roll cylinder 5 is maintained in the slightly downward sloped portion 9a of the angular slot 9 whereby the force acting in the upward direction on rod 7 possesses only a relatively small horizontal break-a-way component at armature 3. In addition to being able to retain armature 3 in the unstable hold position with a rather small magnetic structure, the release mechanism is also most efficient, fast acting and wear-resistant.

In the modified embodiment of the invention as illustrated in FIG. 3, the components which correspond in structure and function to those in FIGS. 1 and 2 have been assigned the same reference numerals. The difference between this embodiment and the previous one is thatthe lower end 9a of the angular slot 9 is horizontal and co-axial with the guideways 1a of the housing for the magnet annature 3. The desired mechanical advantage of requiring a relatively small amount of mag net force to control a rather large amount of upward force exerted on rod 7 is achieved in that when the release mechanism is in the hold position as depicted in FIG. 3, the draw straps 6 have a slight inclination relative to the vertical direction of movement of rod 7. In this manner, only a small horizontal component of force is exerted on'armature 3 in the break-a-way direction, i.e., to the left.

In the further modified embodiment of the invention as illustrated in FIG. 4, which is somewhat similar to FIG. 3, the lower part 9a" of the angular slot 9" is also horizontal but the draw straps are different, the straps 4 being eliminated and their function integrated into a single pair of straps 6' which have an L-shaped configuration, the lower parts 6a carry the magnet armature 3 directly thus eliminating the need for guiding movement of the armature, which saves space and is move economical, and the roll 5 being mounted for rotation about its axis at the junction between the two parts 6a and 6b of the straps. As will be seen by comparison of FIG. 4 with FIG. 3, the upwardly extending portions 6b of the draw straps in FIG. 4 likewise have a slight inclination relative to the vertical direction of movement of release rod 7 and hence also only a small horizontal component of force is exerted on armature 3 in the break-a-way direction when the mechanism is in its hold position unstable equilibrium as depicted in the drawing.

We claim:

1. A device for initiating release of the contacts of an electrical switch comprising an actuating rod tensioned in the upward release direction, and means retaining said actuating rod in a downward position until released including a cylindric roll operable within a stationary slate provided with an angular slot, said roll being coupled to said actuating rod and being maintained in a state of unstable equilibrium by the magnetic attractive .force of a hold-release magnet having an armature to which said roll is also coupled, and said roll and angular slot being so designed that the upwardly directed tensional force applied to saidroll by said actuating rod exerts a relatively smaller horizontal break-a-way component at the armature of said holdrelease magnet.

2. A device as defined in claim 1 for initiating release of the contacts of an electrical switch wherein said angular slot includes an upper part extending upwardly and a lower part sloping slightly downward from the horizontal, said roll being connected to said actuating rod by a first pair of parallel spaced rigid straps pivotally connected at the opposite ends thereof to the opposite ends of said roll and to said actuating rod, and said roll being pivotally connected to said magnet armature by a second pair of parallel spaced rigid straps connected at the opposite ends thereof to the opposite ends of said roll and magnet armature, and said roll being retained in the lower part of said slot in the hold position of said magnet. 1

3. A device as defined in claim 1 for initiating release of the contacts of an electrical switch wherein said angular slot includes an upper part extending upwardly and a lower part extending horizontally, said roll being a connected to said actuating rod by a first pair of parallel spaced rigid straps pivotally connected at the opposite ends thereof to the opposite ends of said roll and to actuating rod, and said roll being pivotally connected to said magnet armature by a second pair of parallel spaced rigid straps connected at the opposite ends thereof to the opposite ends of said roll and armature, said roll being retained in the lower part of said slot in the hold position of said magnet, and said first pair of straps being inclined at a slight angle to the vertical direction of movement of said actuating rod in the hold position of said magnet. A

4. A device as defined in claim 1 for initiating release of the contacts of an electrical switch wherein said angular slot includes an upper part extending upwardly movement of said actuating rod in the hold position of said magnet, and said roll being retained in the lower part of said slot in the hold position of said magnet.

UNKTE STATES PATENT owict CEETEMCATJE CF CCECTWN v 7 Karl Buhler et a1. Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1 line 6 "slate" should be plate Claim 4 (5th Column) line 3, "part should be said Signed and sealed. this 12th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM po'mso USCOMM-DC eoz-ne-pes i U.S. GOVERNMENT PRINTING OFFICE: 1969 0-365-334,

lemme STATES PATENT oFF cE QERFEEFEQATE @F QGRRECTEQN Patnt N00 3,768,052 A Dated October 23, 1975 Karl Buhler et a1. Inventor(s) 1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1 line 6 slate should be plate Claim 4 -(5th Column) line 3,, "part" should be "said Signed and sealed. this 12th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 'fi' UvSA GOVERNMENT PRINTING OFFICE I969 0-366-334,

Claims

1. A device for initiating release of the contacts of an electrical switch comprising an actuating rod tensioned in the upward release direction, and means retaining said actuating rod in a downward position until released including a cylindric roll operable within a stationary slate provided with an angular slot, said roll being coupled to said actuating rod and being maintained in a state of unstable equilibrium by the magnetic attractive force of a hold-release magnet having an armature to which said roll is also coupled, and said roll and angular slot being so designed that the upwardly directed tensional force applied to said roll by said actuating rod exerts a relatively smaller horizontal break-a-way component at the armature of said hold-release magnet.

2. A device as defined in claim 1 for initiating release of the contacts of an electrical switch wherein said angular slot includes an upper part extending upwardly and a lower part sloping slightly downward from the horizontal, said roll being connected to said actuating rod by a first pair of parallel spaced rigid straps pivotally connected at the opposite ends thereof to the opposite ends of said roll and to said actuating rod, and said roll being pivotally connected to said magnet armature by a second pair of parallel spaced rigid straps connected at the opposite ends thereof to the opposite ends of said roll and magnet armature, and said roll being retained in the lower part of said slot in the hold position of said magnet.

3. A device as defined in claim 1 for initiating release of the contacts of an electrical switch wherein said angular slot includes an upper part extending upwardly and a lower part extending horizontally, said roll being connected to said actuating rod by a first pair of parallel spaced rigid straps pivotally connected at the opposite ends thereof to the opposite ends of said roll and to actuating rod, and said roll being pivotally connected to said magnet armature by a second pair of parallel spaced rigid straps connected at the opposite ends thereof to the opposite ends of said roll and armature, said roll being retained in the lower part of said slot in the hold position of said magnet, and said first pair of straps being inclined at a slight angle to the vertical direction of movement of said actuating rod in the hold position of said magnet.

4. A device as defined in claim 1 for initiating release of the contacts of an electrical switch wherein said angular slot includes an upper part extending upwardly and a lower part extending horizontally, said roll having secured thereto at its opposite ends a pair of parallel spaced L-shaped rigid straps, the lower parts of said straps extending horizontally carrying the armature of said magnet, the upper parts of said straps being pivotally secured to said actuating rod and disposed at a slight inclination relative to the vertical direction of movement of said actuating rod in the hold position of said magnet, and said roll being retained in the lower part of said slot in the hold position of said magnet.