US2825787A - Driving mechanisms for circuit breakers - Google Patents

Description

March 4, 1958 H. A. HIDDE NIJLAND ,3

DRIVING MECHANISMS FOR CIRCUIT BREAKERS Filed March-25, 1957 United States Patent DRIVING MECHANISMS non ClRCUIT BREAKERS Hendrik A. Hidde Nijland, Laren, Netherlands, assignor to N. V. Coq, Utrecht, Netherlands, a company of the Netherlands Application March 25, 1957, Serial No. 648,429

Claims priority, application Netherlands March 27, 1956 2 Claims. (Cl. 20ll155) The invention relates to a driving mechanism for an electric circuit-breaker comprising, in combination, a stationary part, a movable part, at least one high speed opening :and closing switching contact carried by said movable part, at least one spring adapted to be biased for the opening movement of said contact, at least one spring adapted to be biased for the closing movement of said contact, locking devices being adapted to move automatically into their locking positions during the tensioning of the springs to keep the tensioned springs under tension, a movable intermediate member connected to said contact carrying movable part through said opening spring and its associated locking device and to the stationary part of the mechanism through said closing spring and its associated locking device, an operating member acting on said intermediate member and being adapted to move it in a direction in which all springs are brought under tension simultaneously and the locking devices are brought into their locking positions, means for releasing the locking devices and a fixed stop member defining the end position of the intermediate member in which all springs are released.

A driving mechanism of the kind referredto has been disclosed in the U. S. patent specification 2,734,270. The invention has the object to modify said known driving mechanism in such a manner that it can be better adapted to certain requirements than said known driving mechanisms. In order that the movable switching contact is separated with certainty from the cooperating fixed switching contact during the opening operation the spring for opening the circuit-breaker must have a great excess of force. Especially when the circuit-breaker will have to open on a short-circuit, a great force may be required to relatively move the switching contacts held tightly together by the electro-dynamic forces. As soon as the contacts start their relative movement the force, which under these circumstances is only required for giving the movable switching contact a speed sufiicient for the extinguishing of the switching arc in the right way, need not be so great any more, so that weaker springs would sulfice.

Since in the closed condition of the circuit-breaker the closing spring is almost entirelyreleased and may not be biased too much it may be possible that the additional force exerted by it on the movable switching contact during the opening operation will not be suflicient. According to the invention improvement of the driving mechanism with respect to the generation of a considerably increasing starting force during the opening operation is possible when the catch-coupling provided between the intermediate member and the contact carrying movable part is a coupling with amplifying force transmission.

For the elucidation reference is made to the accompanying drawing illustrating diagrammatically a driving mechanism according to the invention in three different operating positions.

In the drawing 1 designates a switching rod adapted to be axially moved up and down and to cooperate with 'ice fixed switching contacts 2, 3, to which, in a manner not shown, the circuit to be closed and opened by the circuit breaker is connected. The switching rod 1 is connected through an insulator 4 to an arm 5 of a bell-crank 5, 7 which is rotatably mounted on a pivot 6. In the opened condition of the circuit breaker, shown in Fig. 1, the arm 7 of the bell-crank 5, 7, is in contact with a fixed abutment 8. The arm 7 is connected through one or more springs 9 to the arm 10 of a lever 10, 12 adapted to be swung about a pivot 11. In Fig. 1 the lever 10, 12 lies with its arm 12 against a fixed stop member 13. The arm 12 is coup-led through one or more springs 14 to a stationary part 15 of the circuit breaker.

The invention relates to a driving mechanism, in which at the beginning of the opening movement of the movable switching contact an additional force is exerted on said contact. It consists in that the contact carrying movable part and the locking device are so constructed as to keep the intermediate member in an intermediate position at a certain distance from the said stop member, when the circuit-breaker is in its closed condition, and a catch-coupling is provided which temporarily connects said contact carrying movable part directly with said intermediate member, when the latter is in its intermediate position, and permits the closing spring to :add its force through the intermediate member and said coupling to the force exerted by the opening spring on said movable part until, after the locking device for the opening spring has been released, said intermediate member is pulled against said stop member. The result. of this construction is that when the locking device for opening the circuit-breaker is released the intermediate member is drawn through a small distance against its stop member not only 'by the opening spring but also by the closing spring so that the force, with which the movable switching contact is started to move is considerably increased.

The two- armed lever 19, 12 constitutes an intermediate member which is adapted to be driven by an operating mechanism. This operating mechanism consists of a toggle lever formed by the links 16, 17 and a handle 19, 20 which is rotatably mounted on the shaft 18 and is capable to engage the link 17. To that end the arm 24) is provided with a stud 21 adapted to engage the link 17 of the toggle lever. The arm 7 of the bellcrank 5, 7' is also secured to a locking rod 22 provided with a catch .3 which cooperates with a stud 24 attached to the arm 1%) of the intermediate member 10, 12.

For the operation of the driving mechanism having the task to close and to reopen the circuit breaker the handle 19, 2 9 is swung about its shaft counterclockwise. The result thereof is, that the toggle lever 16, 17 is moved through its stretched position against a fixed abutment 25. Due to this movement of the toggle lever the intermediate member 10, 12 is rotated counterclockwise about the pivot 11, whereby the springs 9 as well as the springs 14 are tensioned (Fig. 2). If the handle 19, 20 should be released in the position according to Fig. 2 the springs 9 and 14 are kept under tension, since the toggle lever 16, 17 remains in its locking position. As soon as the intermediate member 18, 12 has reached the position, in which the springs 9, 14 are tensione-d, the locking rod 22 engages with its catch 23 the stud 24, so that the springs 9 for the opening movement of the circuit breaker are kept under tension.

The link 17 of the toggle lever 16, 17 constitutes one arm of the free rotatable bell- crank 17, 26 which is rotatably mounted on the shaft 18 of the handle 19, 20. When the handle 19, 20 is swung from its position shown in Fig. 2 in a clockwise direction it will engage with its stud 21 the arm 26 just before it reaches its starting position, whereby the toggle lever 16, 17 is turned out 3 ofits locking position and the closing springs 14 are permitted to release their tension. The result thereof is, that the intermediate member 10, 12 is moved with high speed towards the stop member 13 and that due to the action of the locking rod 22 the bell-crank 5,- 7 is moved t tigeth'er with the intermediate member'- and brought into th'elpdsition illiis'trated in Fig. 3, in which the bell-crank 5,7 is lying eagainst'theabutment 8a and the arm 12 of the intermediate member is still at a small distance from the stop member 13. In this position the switching rod 1 interconnects the switching contacts 2, 3 and the circuit breaker is closed.

If it is desired to open the circuit breaker, it is necessary to release the rod 22 from its locking position, sfo tliat'tlieopening springs 9 are allowed to draw the bell-crank S, 7 together with the switching rod 1 back to its starting position against the fixed abutment 8. The release of the locking rod 22 is carried out by means of auxiliary device consisting of a rotary three armed lever or bell- crank 29, 30, 31, of which the'axis of rotation is shown at 23. The arm 29 of said bell-crank is connectd to the handle '19, through a rod 32 provided with a slot 33. The arm engages with a stud 34 the lower face of the locking rod 22 and the arm 31 is loaded by a spring 35 and cooperates with a pawl 36, 37, which is pivotally mounted about an axle 38 and may be unlocked with the aid of a slidable rod 39 provided with a push-button 40. When the handle 19, 29 is swung counterclockwise the three armed lever 29, 30, 31 is moved and the spring 35 is tensioned and kept under tension, when the hook of the pawl 36 engages the arm 31. At the same time the stud 34 of the arm 30 is lowered to such extent that the catch 23 of the locking rod 22 is free to engage the stud 24 of the intermediate member 10, 12 as soon as the springs 9 and 14 have reached'their tensioned conditions. In order to open the circuit breaker it isonly necessary to push the button 40. This results in releasing the pawl 36, from the bell- crank 29, 39, 31, so that the latter is permitted to be rotated about its pivot 28 by the spring 35, the stud 34 lifts the rod 22 a bit and the lock of the tensioned opening springs 9 is released.

The intermediate member 10, 12 is provided with a short third arm 41, which is linked to a rod 43 mounted for sliding movement in a bushing 42. Said rod is provided with a cross-pin 44. The bell-crank 5, 7 has a relatively long third arm 45. When the circuit-breaker is its closed condition (Fig. 3) said arm 45 is nearly in contact with said cross-pin 44.

Now, if the circuit-breaker is in its closed condition (Fig. 3) and has to be opened, the locking rod 22 will have to be released. After said rod has been released the intermediate member 10, 12 will be pulled against the stop member 13 both by the opening springs '9 and by the closing springs 14. When the intermediate member 10, 12 is thus rotated the bell-crank 5, 7 is rotated together therewith in the opening direction owing to the catch-coupling consisting of the arm 41, the rod 43, the cross-pin 44 and the arm 45. After the intermediate member 10, 12 has touched the stop member 13 the further rotation of the bell-crank 5, 7, that means 4 th opening movement of the switching rod 1, is duly caused by the opening springs 9. From this construction it appears, that at the beginning of the opening movement of the switching rod 1 the force exerted thereon is con siderably amplified not only due to the cooperation of the springs 9 and 14 but also owing to the amplifying force transmission 4145, so that, even when the cooperating switching contacts solidly stick together and resist their relative sliding movement due to great friction, the circuit-breaker will be opened with certainty, I

It will be obvious that the handle 19, 29 may be replaced by a motor gear. Together with the illustrated device for releasing the toggle lever 16, 17 from its locking positions by means of the handle 19, 20 or a motor gear an electromagnet for the closing of the circuit breaker may be provided, said electromagnet operating on the toggle lever 16, 17 in any suitable manner. Also for opening the circuit breaker an electromagnet may be used, so that the circuit is adapted to be operated from a distance.

What I claim is:

l. A driving mechanism for an electric circuit-breaker comprising, in combination, a stationary part, a movable part, at least one high speed opening and closing switching contact carried by said movable part, abutmentsdetiming the end positions of said movable part, at least one springiadapted to be biased for the opening movement of said contact, at least one spring adapted to be biased for the closing movement of said contact, locking devices being adapted to move automatically into their locking positions during the tensioning of the springs to keep the tensioned springs under tension, a movable inter mediate member connected to said contact carrying movable part through said opening spring and its associated locking device and to the stationary part of the mechanism through said closing spring and its associated locking device, an operating member acting on said intermediate member and being adapted to move it in a direction in which all spiings are brought under tension simultaneous- 1y and the locking devices are brought into their locking positions, means for releasing the locking devices, a fixed stop member defining the end position of the intermediate member in which all springs are released, said contact carrying movable part and the locking device connected therewith keeping the intermediate memher in an intermediate position at a certain distance from said stop member when the circuit-breaker is in-its closed condition, and a catch-coupling temporarily connecting said contact carrying movable part directly with said intermediate member when the latter is in its intermediate position, said catch-coupling permitting the closing spring to add its force through the intermediate member and said coupling to the force exerted by the opening spring on said movable part until, after the locking device of said opening spring has been released, said intermediate memher is pulled against said stop member.

2. A driving mechanism as claimed in claim 1, characterized in that the catch-coupling provided between the intermediate member and the contact carrying movable part is a coupling with amplifying force transmission.

No references cited.

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