EP0450194A1

EP0450194A1 - Switch drive mechanism

Info

Publication number: EP0450194A1
Application number: EP90200563A
Authority: EP
Inventors: Tjoan Sioe Rutger Tan
Original assignee: Holec Systemen en Componenten BV
Current assignee: Holec Systemen en Componenten BV
Priority date: 1988-12-08
Filing date: 1990-03-08
Publication date: 1991-10-09
Also published as: AU5206090A; AU619666B2; NL8803018A

Abstract

Drive mechanism for a switch having one or more separate switching units (106). The drive mechanism comprising a combined drive and actuating spindle (1) for driving an overturn point mechanism (3, 4, 5) which acts on the switching unit (106) indirectly by means of an arm (2, 6) mounted on the drive and actuating spindle (1), a lever (7) pivotably supported at one end and a linking overrun coupling (121). Locking means (13) are present for retaining the switching units (106) in the switched-on state by locking the lever (7). The locking means (13) are coupled to the arm (2, 6) on the drive and actuating spindle (1) in order to release the locking of the lever (7) after passing the turn over point during movement of the drive and actuating spindle (1).

Description

The invention relates to a drive mechanism for a switch composed of one or more separate switching units, comprising

a) a drive spindle for driving
b) an overturn point mechanism with which
c) an actuating spindle can be moved to a selected end position, in which end position the switching units are in the switched-on or switched-off state.

Drive mechanisms for switches provided with an overturn point mechanism or snap-through mechanism are known in many forms and are generally used because of the advantage that such a mechanism has two defined states, with the result that the on and off position of a switch can also be determined thereby. Furthermore, such a mechanism always operates with a known speed as soon as the overturn point has been passed.
If the overturn point mechanism acts directly on a switch in which a specified constant contact pressure is required, the disadvantage emerges that the contact pressure drops if the mechanism is set from the defined on position to the off position. This has a disadvantageous effect on the breaking capacity of the switch.
The object of the invention is therefore to provide a drive mechanism in which use can be made of an overturn point mechanism without the disadvantage mentioned in this connection of contact pressure reduction occurring, with the mechanism also being simple in construction.
For this purpose, the drive mechanism described in the introduction is characterized in that

the drive spindle and actuating spindle are constructed as one spindle;
the overturn point mechanism acts on the switching units indirectly by means of, respectively, an arm mounted on the drive and actuating spindle, a lever supported at its one end so as to pivot and a linking overrun coupling;
locking means are present for retaining the switching units in the switched-on state, against the action of spring means acting in the switch-off direction, as long as the overturn point mechanism is in the switched-on state in front of the overturn point.

Because the overturn point mechanism can be moved towards the off position past the overturn point in the drive mechanism according to the invention without the switch switching off, no contact pressure reduction will occur. In addition, less mass has to be moved during switching-off, and this advantageously affects the switching-off speed and, consequently, also the breaking capacity of the switch. Furthermore, it is possible, by this uncoupling of the mass and by using diverse switch springs, to determine the switching-on and switching-off speeds independently of each other, with the result that a substantial optimization of the required switching energy is achieved.
A further object of the invention is to make the invention suitable in a simple manner for a switch in which the switching units are not mutually connected to one another, except for a switch in which the switching units are connected to one another with a bridge or the like in order to achieve a simultaneous switching of the switching units.
The invention is characterized for this purpose in that

the switching units are arranged in a row and situated in a plane parallel to the actuating spindle;
the drive and actuating spindle and the overturn point mechanism are constructed in a shared form for all the switching units;
the locking means and actuating means present for the simultaneous or virtually simultaneous actuation of the switching units are constructed separately for each switching unit, the actuating means being composed of
- . switching cranks fitted on the actuating spindle at an identical angle;
- . levers attached at their one end so as to pivot;
- . switch springs acting on the levers in the switch-off direction;
- . linking overrun couplings.

In this manner, a further reduction is achieved in the mass during switching-off and thus a further contribution is made to a beneficial breaking capacity. In addition, a simultaneity of switching is achieved in a simple and reliable manner.
The invention can also be made suitable in a simple manner for reducing or even completely preventing undesirable switching phenomena on the load side. For this purpose, the invention is characterized in that at least one of the switching pawls interacts with the associated switching crank in a manner such that the switching unit concerned opens at a predetermined time before the other switching units. In this way, for example, the so-called virtual chopping which may occur, in particular, if vacuum switches are used can be completely prevented. If the desired difference in time cannot be achieved as a consequence of the high speeds with which the switching units switch off, the drive mechanism can be adapted for this purpose with the aid of the measures according to Claims 5 and 6.
According to a further elaboration of the invention, the drive mechanism is characterized in that the switch springs acting on the levers are composed of at least one contact force spring, the contact force spring being fitted on the overrun coupling and being directly coupled to the lever and indirectly, via the overrun coupling, to the coupling rod all this in a manner such that, on the one hand, the coupling rod can be moved directly by the lever to the on position and, on the other hand, can be moved to the off position only after the lever has traversed a certain path. Because the switch spring interacts in this manner with the lever and coupling rod, it is possible to separate the contacts with a certain starting speed, the so-called "hammer stroke". This provides more certainty that the contacts will be separated from each other even if they are accidentally stuck. In addition, the contact force, the stroke and the like, inter alia, can be adjusted simply in this manner and are therefore insensitive to manufacturing and assembly tolerances, and also to wear occurring during the service life.
In order to be able to optimize the drive mechanism further, the invention furthermore provides the facility of using a compensation spring according to Claims 9, 10 and 11. The switching-on and switching-off speed, inter alia, can be influenced by means of said compensation spring and even if vacuum switches are used, for example, the effect of the atmospheric pressure can be eliminated.
By using separate switch springs in a manner as is done in the case of the invention, the greatest possible freedom is achieved with respect to their effect on the overall switching action in the drive mechanism and the drive mechanism can be optimized.
Although the actuating spindle can also, of course, be driven directly, the invention also provides for actuating at right angles to said actuating spindle, the drive mechanism being made completely independent of the speed with which the switching units are actuated. The invention has the characteristics according to Claim 12 for this purpose.
The object of the invention is furthermore a drive mechanism which can be coupled to, and/or locked with, other switching and/or safety components such as isolation and/or selection switches and/or fuses in a simple but reliable manner and is consequently suitable for use in distribution stations.
The subclaims 13 to 16 inclusively reveal the simple manner in which the invention can comply with the requirements for preventing incorrect switching operations and for guaranteeing that maintenance activities can be carried out safely and reliably on a distribution station incorporating the mechanism according to the invention. The interaction with a fuse which is generally present in the case of a distribution station and protects the transformer can be achieved very simply, as Claim 17 indicates.
If such a fuse blows, the switching units are switched off in a reliable manner.
The invention therefore provides a simple but reliable mechanism which can easily be made suitable for a large number of uses.
From the description of the figures it will be evident that various design solutions which are known per se can be used in the invention in order to achieve certain characteristics but all of these fall within the scope of the invention. Thus, for example, an eccentric bush can be fitted on the pin of a switching crank in order to achieve time-shifted switching of different phases. The switch springs may also be constructed in diverse manners and fitted in diverse places.
A preferred embodiment of the drive mechanism according to the invention will be explained in more detail below as an example, with reference to the accompanying figures.
Figures 1a and 1b show diagrammatically the principle of the drive mechanism according to the invention, with open switching unit and with closed switching unit respectively.
Figure 2 shows a three-dimensional cutaway diagrammatic drawing of a three-phase switch in which a drive mechanism according to the invention is included. Figure 3 shows diagrammatically a locking system which blocks switching-off of two phases until the first phase has actually been switched off.
Figure 4 shows a three-phase switch according to Figure 2 provided with further switching and safety components and the associated couplings and locking systems.
Figure 5 shows diagrammatically a ring line with distribution stations in which the drive mechanism according to the invention can be used.
Figure 6 shows a diagram of a distribution station such as is used with the ring line according to Figure 5, in which switches incorporating the drive mechanism according to the invention have been incorporated.
It is pointed out in advance that the drive mechanism according to the invention is designed, on the one hand, to meet the requirements imposed by the switching units to be switched and, on the other hand, by the manner of installation in a switch box. The arrangement is at the same time designed also to accommodate further switching and safety components which are generally necessary in the case of use in a distribution station and to be able to house their actuation and locking systems with respect to the switching units in a simple manner and using simple means.
Figures 1a and 1b show diagrammatically the principle of the drive mechanism according to the invention. It relates to the switching unit 106 depicted diagrammatically in the figures as a vacuum switch 102 with contacts 104 and 105. The vacuum housing of the switch is sealed by means of bellows 103 and a leakage-free lead-through of the coupling rod 10 is possible. As a result of the vacuum prevailing in the switch, a certain force is always exerted by the ambient pressure on the coupling rod 10 in the closing direction of the contacts, that is to say, switching-on of the switch. The main components of the drive mechanism furthermore comprise a lever 7, one end of which (right-hand end) is mounted in B so as to pivot. The lever 7 is linked with the coupling rod 10 of the switching unit 106 by means of a linking overrun coupling 121. The lever 7 is linked by means of a pivoting link 092 to a bush 091 of the spring holder 9, which is mounted around the coupling rod 10 so as to slide. Fitted beneath the spring holder 9 is a switch spring 12 round the coupling rod 10 whose other end rests against a spring cup 101 which is securely attached to the coupling rod 10. The free end of the spring holder bush 091 rests, according to Figure 1a, against a stop 11 which is securely attached to the end of the coupling rod 10. Consequently, the switch spring 12 is therefore linked directly to the lever 7 and indirectly to the coupling rod 10. The lever 7 is pressed upwards to the switched-off state according to Figure 1a by a switch spring 12. As shown in Figures 1a and 1b, a switch spring 8 may be used, if desired, to assist in the switching-off and, if vacuum switches are used, to compensate for the atmospheric pressure. Said switch spring 8 can be fitted at any suitable position and may also be constructed, for example, as a tension spring, helical spring and the like. In Figure 1b, the lever 7 is depicted in the switched-on position of the switching unit 106. As is evident from Figure 1b, the lever 7 has been swung further after the contacts 104 and 105 in the switching unit 106 have touched each other. As a result, the stop 11 is freed from the top of the spring holder bush 091. The consequence thereof is that the force of the switch spring 12 determines the contact pressure so that the switch spring 12 may also be termed the contact-force spring. During switching-off, the lever 7 travels upwards and accelerates under the influence of the force of the switch springs 12 and 8 and strikes the stop 11 at an appreciable velocity, with the result that the contacts 104 and 105 are separated from each other abruptly and rapidly by means of the coupling rod 10, as is desirable not only to switch off rapidly and to increase the breaking capacity as much as possible but also nevertheless to be able to separate accidentally stuck contacts by means of the stroke and to switch off. In the switched-on state according to Figure 1b, the lever 7 is held in the desired position by the switch-off pawl 13, which is held in the locked state under the influence of the force of the restoring spring 131. The switch-off pawl 13 is mounted on a fixed spindle 132 so as to pivot. As is evident from Figure 1a and has already been noted above, it is possible to use a switch spring 8 with which, if vacuum switches are used, a force can at least be exerted on the lever 7 which compensates for the force exerted by the atmospheric pressure on the coupling rod 10 as a consequence of the vacuum. Said switch spring 8 may therefore also be termed a compensation spring. The force exerted by said switch spring 8 may also be used to increase the switching-off speed and/or to damp the switching-on speed. The construction and position at which said switch spring 8 is used is governed thereby.
The actuation of the lever 7 takes place during switching-on with the aid of an overturn point mechanism or snap-through mechanism known per se which operates on the actuating spindle 1. As shown, the latter crosses the lever 7 at some distance from the pivot point B thereof. For this purpose, there is, attached to the actuating spindle 1, an arm 3 whose end A is acted on by the switch compression spring 5. In order to guide the switch spring 5, the latter is mounted on a telescopic rod 4 which is attached to the fixed part of the switch box at the point C so as to swivel. If the actuating spindle 1 is rotated clockwise, according to Figure 1a the arm 3 will swing downwards until the point A reaches the connecting line X-Y between the actuating spindle 1 and the pivot point C, at which instant the switch spring 5 is under maximum stress, with the result that, if the actuating spindle 1 is rotated further, the switch spring 5 is capable of rotating the actuating spindle 1 further with force and high speed with the aid of the arm 3 to the position shown in Figure 1b. As the connecting line X-Y is passed, the overturn point or snap-through point of the mechanism is traversed by the point A. The switching arm 2 with the switching crank 6 at its end, which arm is displaced through an angle α with respect to the arm 3, is attached to the actuating spindle 1. If the actuating spindle 1 rotates, the switching arm 2 with the switching crank 6 at its end therefore swings concomitantly. In doing so, the latter approaches the lever 7 and makes contact with the lever 7 after the point A has passed the overturn point or snap-through point. The switch spring 5 then forces the point A of the arm 3 further in the clockwise direction, as a result of which the switching crank 6 causes the lever 7 to swing downwards to the position of Figure 1b, as a result of which the contacts 104 and 105 first make contact with each other, with the result that the switch is closed, and then the contact-force spring 12 is further compressed until the switch-off pawl 13 locks the end of the lever 7 in that position.
To switch off, the actuating spindle 1 is now rotated anticlockwise, as a result of which the arm 3 again compresses the switch spring 5 until the overturn point or snap-through point is reached and, on rotating further, the switch spring 5 assists and continues the rotation of the actuating spindle until the concomitantly swinging switching crank 6 makes contact with a diagrammatically shown coupling lever 133 at the point 134. Said lever 133 pivots around the fixed point 135 and its other end 136 forces the switch-off pawl 13 against the force of the spring 131 and in an anticlockwise direction, with the result that the lever 7 is released and, under the influence of the force of the switch springs 12 and 8, abruptly opens the contacts and continues to travel until the state shown in Figure 1a is reached. (The diagrammatically shown lever 133-136 is depicted in Figures 1a and 1b alone in order to explain the operation but does not appear in a preferred embodiment according to Figure 2. In the latter case, the switching crank 6 acts directly on the switch-off pawl 13. The action is, however, identical.).
It will be clear to the person skilled in the art that a number of stops necessary for limiting the movements and rotations have not been shown for the sake of clarity.
From the above description of the switching unit 106 it follows that the switching unit is switched on and switched off by means of this simple device with a defined speed and in a reproducible manner. In addition, the switching-on and switching-off speed and the contact pressure can be adjusted independently of each other by using the switch springs 5, 8 and 12 and can therefore be satisfactorily optimized. The number of moving parts is particularly small and their mass is also small, with the result that a long service life may be expected. The switching-on speed beyond the overturn point is independent of the speed with which the actuating spindle is initially rotated. The switching-off speed is higher because the concomitantly moving mass of the mechanism has been reduced. The contact force continues to be maintained during the first section of the switching-off movement after which the contact separation takes place with a so-called "hammer stroke", which is also advantageous in the case of accidentally stuck contacts. Finally, it may be stated that the contact force, the stroke energy and the like can be adjusted and are therefore insensitive to manufacturing tolerances and wear during the service life.
Figure 2 shows, in the form of a cutaway three-dimensional diagram, the structure of a preferred embodiment of the drive mechanism according to the invention as used in a three-phase switch. The mutual position of the different parts is only of importance with a view to a structurally simple switch in which account has already been taken of the facility for interaction with other components. Other arrangements are, of course, possible within the principle. Three levers 7, one for each phase, are situated next to one another in one and the same plane. These actuate the coupling rods 10 of the switching units 106 by means of the overrun couplings 121. The latter are shown diagrammatically by R, S and T for the three phases. The levers 7 are mounted so as to swivel by means of their one end at B at fixed points, which are not shown in more detail, of the frame of the switch box. The actuating spindle 1 extends in a plane which is parallel to the levers 7 and perpendicular to the latter and is rotatably supported in the box in diagrammatically shown bearings. Below the actuating spindle 1, sections of the levers 7 are shown in detail, specifically in the form of strips 071 which each contain a window 072. The switch-off pawls 13 which are pressed against the end of the windows 072 facing away from the pivot B by the restoring springs 131 project into said windows. In the state depicted in Figure 2, the levers 7 are in the switched-on position and are locked by the switch-off pawls 13. The overrun couplings 121 of the switching units 106 are therefore in the position shown in Figure 1b.
At the position of each lever 7 a switching crank 6 is attached to the actuating spindle 1 via switching arms 2. For each phase R, S and T, said switching cranks 6 are identically oriented. An arm 3 whose end A is acted on by the switch spring 5 of the overturn mechanism or snap-through mechanism is furthermore attached to the actuating spindle 1. The switch spring 5 is mounted around a telescopic rod 4, the one end of which is attached so as to pivot at the point A of the arm 3 and the other end of which is attached so as to pivot at the point C to the frame of the box. The operation and the position correspond to those explained and depicted in Figures 1a and 1b. From Figure 2 it is therefore evident that separate actuating and locking means are used for each switching unit of each phase. However, only one actuating spindle having one overturn point mechanism 3, 4, 5 is used for all the phases. The drive mechanism according to the invention can, however, also be satisfactorily used for a switch in which the phases are rigidly coupled to one another. In that case, the actuating and locking means are of shared construction.
It follows from the explanation in the case of Figures 1a and 1b that, after rotating the actuating spindle 1, initially against the force of the switch spring 5, until the overturn point on the line X-Y has been passed, the force of the switch spring 5 has to continue rotating the actuating spindle 1 at the desired high speed. This means that the drive of the actuating spindle 1 has to be provided with overrun couplings which, after the overturn point has been passed, makes it possible for the actuating spindle 1 to move freely under the influence of the switch spring 5. For driving directly on the actuating spindle 1, said overrun couplings can be constructed in diverse manners which are known per se. If the ends of the actuating spindle 1 are difficult to get at, for example as a result of assembly, the drive can be achieved by a separate drive spindle. For this purpose, the link between the drive spindle 21 and the actuating spindle 1 is formed, according to a preferred embodiment, by a very simple overrun coupling 22, 23. The drive spindle 21 crosses the actuating spindle 1 at right angles and at some distance, and is furthermore mounted in the frame of the box. In the region near the point where the drive spindle 21 and the actuating spindle 1 cross each other, the drive spindle 21 is provided with a drive crank 22 having a pin. During rotation, the latter is able to interact with a transmission crank 23 which is also mounted on the actuating spindle 1. Said transmission crank 23 is provided with two crank pins which are staggered through a peripheral angle with respect to each other. Said peripheral angle is determined by the angle through which the actuating spindle 1 rotates after the overturn point has been passed and should be at least as large. Said peripheral angle should also be limited in such a manner that, in the rest state, one of the crank pins of the transmission crank 23 can be driven by the pin of the drive crank 22. The switching cranks 6 of the actuating spindle 1 are attached to the actuating spindle 1 in a manner such that they make contact with the levers 7 at the instant when the overturn point has been passed. If the drive spindle 21 is now rotated anticlockwise according to Figure 2, the drive crank pin 22 will move the uppermost transmission crank pin 23 of the actuating spindle 1 upwards until the switch spring 5 causes the actuating spindle 1 to continue to rotate rapidly after the snap-through point has been traversed, as a result of which the drive crank pin 22 enters freely into the space between the two transmission crank pins 23. The transmission 22, 23 therefore acts as an overrun coupling.
When the drive spindle 21 rotates clockwise in order to rotate the actuating spindle 1 in the switch-on direction, the drive crank pin 22 interacts with the other one of the two transmission crank pins 23 of the actuating spindle 1.
In accordance with what has been said in the case of Figures 1a and 1b in connection with the switch-off pawl 13, the switching crank pin 6 according to Figure 2 acts directly on the free end of the switch-off pawl 13. For this purpose, the pivot spindle of the switch-off pawls 13 is situated on the same centre line as that of the actuating spindle 1. The operation corresponds to that described for Figures 1a and 1b. The link 133 described diagrammatically for Figures 1a and 1b is therefore not present.
Figure 3 shows an example of a manner in which a reproducible time difference can be achieved by mechanical means in the switching off of different phases, with a lock to influence the time difference. Referring to Figures 1 and 2, the three phases with which the components concerned are associated are indicated as an example by the indices R, S and T.
The lever 7 (R) is provided with an additional opening 073 through which the one leg of a further locking pawl 13A (R) is fitted. Said locking pawl 13A (R) is essentially L-shaped and is attached so as to pivot in a fixed point E in the intersection of the two legs. At the end of the leg which projects through the opening 073 of the lever 7, a tension spring or the like 131A functions in a manner such that the locking pawl 13A (R) tends always to rotate in the anticlockwise direction. In the state shown, this is prevented because the other leg is resting against a stop F. If the switch is now switched off, the switching crank 2, 6 will run up against the switch-off pawl 13 (R) and release the lock of the switching unit (R) concerned. At that instant, the switch-off pawls 13 (S, T), which are shown by broken lines, of the other switching units (S, T) have not yet been actuated by the switching cranks 2, 6 concerned because the latter are displaced at an angle a small amount in the counterclockwise direction (S, T). The actuating spindle 1 with the switching cranks 2, 6 (S, T) is retained in said state because the switching crank 2, 6 (R) is up against the other leg of the switch-off pawl 13A (R) which is blocked against rotating clockwise by the lever 7 (R) through which the one leg of the switch-off pawl 13A (R) is fitted. Only when the lever 7 (R) has risen to such an extent that it is situated opposite an indentation 132A in the switch-off pawl 13A (R), will the latter be able to rotate concomitantly in the clockwise direction and thus release the blocking of the switching cranks 2, 6 (S, T), and only after this is it possible for the associated switching units (S, T) to switch off.
Diverse embodiments are, of course, conceivable. The main point remains, however, that a time difference in switching-off can be achieved simply in the case of the invention.
Finally, it should furthermore be stated that the drive spindle 21 is rotated by means of a key, which is not shown, which can be fitted on the end 211 of the drive spindle 21 at the actuating side.
Before discussing Figure 4, a discussion of Figures 5 and 6 first follows for the purpose of clarification.
Figure 5 shows diagrammatically a ring line R which is fed in a known manner from the mains N. The ring line accommodates a number of distribution stations 40 which each feed a number of loads V via a linking transformer T. Each distribution station 40 has two cable connections K of the ring line and a transformer connection T.
Figure 6 shows diagrammatically the interior of a distribution station 40 in which use can advantageously be made of the drive mechanism according to the invention. This shows three fields, specifically the two cable fields K and the transformer field T. Each field is provided with a switching unit 106 which is actuated by a drive mechanism 071. The three fields are linked to one another by a rail system 39. Accommodated in each field between the rail system and the switching unit is a selection switch 261 which can connect the field either to the rail system or to earth. The drive mechanism of the selection switch is shown diagrammatically by 29, 30, 27. As will be explained below, mutual locks are necessary for safe operation between the selection switch and the switching unit, which locks are indicated diagrammatically by 25, 31, 35. It will be clear to the person skilled in the art that only the diagram for one phase is depicted in Figures 5 and 6 and that, for a three-phase mains, all that is depicted for each field is present in triplicate and that the actuating devices of the switches are coupled to one another in a known manner in order to be able to switch the three phases essentially simultaneously. The mutual position of the switches for the different phases and their actuating and drive devices can be deduced from the description for Figure 2.
Figure 4, together with Figure 2, shows the mechanism according to the invention in which the switch for use in a distribution station is furthermore provided with a selection switch 261 for each switching unit 106 of the phases R, S and T. Said selection switches are preferably fitted in a row parallel to and behind that in which the switching units are situated. Of the selection switches only the drive pins 26 are depicted, which drive pins are coupled to one another by means of a bridge 27 and are therefore actuated simultaneously according to this example. For this purpose, a further drive spindle 29 is mounted in the frame of the box, which drive spindle runs parallel to the drive spindle 21 of the switching units. Mounted at the end of the drive spindle 29 is a crank 30, the crank pin of which is able to slide in a slot 28 of the bridge 27. The drive pins 26 of the selection switches can be moved up and down by rotating the drive spindle 29 until specified end positions are reached in which, for example, a connection is made to the rail system or to earth. Just like the drive spindle 21, the drive spindle 29 is provided, at the actuating side of the switch, with an end 291 which is suitable for engaging the separate actuating key.
Since the selection switches are not designed to switch power, locks or cutouts could be provided which make it impossible to switch the selection switches under load. For this purpose, a locking slider 31 can be slid to and fro in guides, which are not shown, parallel to the actuating spindle 1. The locking slider 31 is provided with a number of upwardly open slots 311 situated at a distance from one another such that, in the case of a three-phase switch box, the three levers 7 can drop simultaneously into the slots 311 if they are in the switched-on position as shown in Figures 2 and 4. The locking slider is constructed in a manner such that it can only be slid to and fro if the levers 7 are in the uppermost, switched-off position because they are then situated outside the top of the slots 311. The locking slider is slid as a result of the fact that a crank pin 33 can be displaced in an additional slot 312 provided in the locking slider, which crank pin is attached to the end of a spindle 32 on which, for example, a round selection disc 25 having a handle 251 is mounted. The spindle 32 runs parallel to the two drive spindles 21 and 29. As a result of rotating the selection disc 25 through an angle of, for example, 120°, the crank pin 33 is moved from the position drawn to the position shown by broken lines or vice versa. In this process, the locking slider 31 is first moved to the left in the figure and then moved in turn to the right to the same position. As demonstrated above, this sliding of the locking slider 31, and therefore the rotation of the selection disc 25, can only be carried out if the levers 7 are in the switched-off position. Except for one actuating opening 24, the selection disc 25 is completely solid. It consequently covers in each case one of the actuating ends 211 and 291 of the drive spindles 21 and 29. In the position drawn, however, one actuating end 211 of the drive spindle 21 is accessible so that the actuating key can be fitted on the drive spindle through the actuating opening 24. In this position of the selection switch, the locking slider 31 is in the position depicted so that the actuating spindle 1 can be rotated by means of the drive spindle 21 in order to switch the switching units on or off. It is solely in the switched-off state of the switching units that the locking slider 31 can be slid by rotating the selection disc 25 so that the actuating opening 24 can then be rotated in front of the actuating end 291 of the drive spindle 29 of the selection switch 261. In said selection position, in which the switching units are switched off and cannot be switched on because the actuating end 211 of the drive spindle 21 is covered by the selection disc, the selection switches can be switched to earth or rail with the aid of the actuating key on the drive spindle 29. It is therefore impossible to actuate the selection switches with the locking slider 31 with the switching units switched on.
It will be clear to the person skilled in the art that the rotating selection disc described may also be replaced, for example, by a selection disc making translation movement provided only the one or the other of the drive spindles 21 and 29 is made accessible.
However, it may also be desirable to be able to switch the switching units only when the selection switches are unambiguously in a specified switching state. For this purpose, the drive spindle 29 of the selection switches may furthermore simply be provided with a locking disc 35 mounted thereon which is provided with at least one slot 351. Fitted on the locking slider 31 is a locking pawl 34 which is able to drop into the slot 351 of the locking disc 25 if the drive spindle 29, and therefore the selection switches, are in the correct and desired switching state. It is only then that the locking slider 31 can be moved because the locking pawl 34 is able to penetrate into the slot with the result that the selection disc 25 can be turned back to the position depicted in order to actuate the drive spindle 21 of the load switches. If there is only one slot 351 in the locking disc 35, for example, associated with the non-earth position, that is to say the rail position of the selection switches, the selection disc 25 can only then be turned to the depicted position in which the drive spindle 21 of the switching units can be actuated. Under certain circumstances it may also be desirable to be able to rotate the selection disc into both switching positions of the selection switches. In that case the two slots 351 are necessary in the locking disc 35. It is, of course, quite possible to conceive other embodiments which are not shown and which are able to achieve the same result without, however, departing from the scope of the invention.
Finally, the invention provides for the further combination of the drive mechanism with a safety component. This relates to the automatic switching-off of the switch in the event of the fuse blowing if a fuse is used in a transformer field of a distribution station. In that case, a fuse is used in which a striker pin emerges from the fuse 361 in the event of its blowing. In such a case, after the switch has been switched on by means of the drive spindle 21, it is turned back again past the snap-through point. Normally, all the switching units would immediately be switched off under the influence of the switch spring 5. However, if the said fuse is used, an additional blocking strip 38 is fitted on the actuating spindle 1, which blocking strip 38 assumes a position with respect to the actuating spindle 1 and with respect to a locking lever 37 which is such that the blocking strip 38 comes to rest against the locking lever 37 (as depicted by the broken lines in Figure 4) if the actuating spindle 1 is turned in this manner through the snap-through point. Although the switching cranks 6 are already swivelled aside under these circumstances to such an extent that they are no longer in contact with the levers 7, the latter are still retained in the switched-on position by means of the switch-off pawls 13. After all, the switching cranks 6 have not yet been able to rotate to that position in which they would make contact with the free end of the switching pawls 13. The device is therefore ready for switching off and will also do so instantly as soon as the locking lever 37 releases the blocking strip 38. If the fuse 361 blows, this takes place when the striker pin 36 rotates the locking lever 37 away from the locking position. It will be clear that an additional fuse, which is not shown in more detail, can easily be fitted, namely to guarantee a safe replacement of the fuse in the event of switching off as a result of a fuse blowing.
With the device according to Figures 2 and 4 which has been described diagrammatically and for which the mutual positions and states of the various components have in fact essentially been specified, a compact, readily accessible and easily actuatable switch box can be obtained. The mechanisms used are simple and robust.
To summarise, the mechanism according to the invention complies with the following objectives:

a simple effective mechanism which switches on and off at a specified speed;
a mechanism in which the switching-on and switching-off speeds and contact pressure can be regulated and adjusted independently of one another, with the result that optimum switching conditions are achieved;
a mechanism which is easy to couple to, and to lock with, further switching and/or safety components such as, for example, a selection switch, as a result of which good and safe operation is achieved;
a mechanism which guarantees that a switching is possible only in a correct state of the switching components in, for example, a distribution station and thus prevents locks being released by brute force;
a mechanism which can interact in a simple and reliable manner with a fuse;
a mechanism with which the safety of maintenance activities on a distribution station is ensured in an optimum manner;
a mechanism in which it is possible, in a simple manner, to switch the phases shifted to some extent in time with respect to each other.

Claims

Drive mechanism for a switch composed of one or more separate switching units (106), comprising
a) a drive spindle for driving

b) an overturn point mechanism (3, 4, 5) with which

c) an actuating spindle (1) can be moved to a selected end position, in which end position the switching units are in the switched-on or switched-off state, characterized in that

- the drive spindle and actuating spindle (1) is constructed as one spindle;

- the overturn point mechanism acts on the switching units (106) indirectly by means of, respectively, an arm (2, 6) mounted on the drive and actuating spindle (1), a lever (7) supported at its one end so as to pivot and a linking overrun coupling (121);

- locking means are present for retaining the switching units (106) in the switched-on state, against the action of spring means acting in the switch-off direction, as long as the overturn point mechanism is in the switched-on state in front of the overturn point.
Drive mechanism according to Claim 1, characterized in that the locking means are composed of a switch-off pawl (13) which can pivot around a spindle, on which switch-off pawl (13) a restoring force (131) continuously acts in the direction of locking of the lever (7) and which interacts by means of its one end with said lever (7), as a result of which the latter can be locked in the switched-on state and which interacts by means of its other end with the arm (2, 6) on the actuating spindle (1) in order to be capable of being swung to the off position during movement of said spindle (1) after passing the overturn point, as a result of which the locking of the lever (7) can be released.
Drive mechanism according to Claim 1 or 2, characterized in that
- the switching units (106) are arranged in a row and situated in a plane parallel to the actuating spindle (1);

- the drive and actuating spindle (1) and the overturn point mechanism (3, 4, 5) are constructed in a shared form for all the switching units (106);

- the locking means and actuating means present for the simultaneous or virtually simultaneous actuation of the switching units (106) are constructed separately for each switching unit, the actuating means being composed of
. switching cranks (2, 6) fitted on the actuating spindle (1) at an identical angle;

. levers (7) attached to their one end so as to pivot;

. switch springs (8, 12) acting on the levers (7) in the switch-off direction;

. linking overrun couplings (121).
Drive mechanism according to one or more of the preceding claims, characterized in that at least one of the switch-off pawls (13) interacts with the associated switching crank (2, 6) in a manner such that the switching unit (106) concerned opens at a predetermined time before the other switching units (106).
Drive mechanism according to Claim 4, characterized in that means are provided with which the difference in time at which the one switching unit (106) opens before the other switching units (106) can be adjusted further.
Drive mechanism according to Claim 4 or 5, characterized in that said means are composed of a further locking pawl (13A) which interacts with, on the one hand, the lever (7) of the switching unit (106) concerned which opens earlier and, on the other hand, the levers (7) of the other switching units (106), in a manner such that the locking of said other switching units (106) is only released after the lever (7) of the switching unit (106) which opens earlier is in a predetermined state, the switching unit concerned being switched-off.
Drive mechanism according to Claims 3 to 6 inclusive, characterized in that the centre line of the pivoting spindle of the switch-off pawl (13) coincides with the centre line of the actuating spindle (1) and in that the centre line of the pivoting spindle of the lever (7) runs parallel to that of the actuating spindle (1) and is essentially perpendicular to the direction of movement of the drive rod (10).
Drive mechanism according to one or more of the preceding claims, characterized in that the switch springs acting on the levers (7) are composed of at least one contact force spring (12), the contact force spring (12) being fitted on the overrun coupling (121) and being directly coupled to the lever (7) and indirectly, via the overrun coupling (121), to the coupling rod (10), all this in a manner such that, on the one hand, the coupling rod (10) can be moved directly by the lever (7) to the on position and, on the other hand, can only be moved to the off position after the lever (7) has traversed a certain path.
Drive mechanism according to Claim 8, characterized in that a compensation spring (8) also operates on the lever (7) and acts thereon in the switch-off direction.
Drive mechanism according to Claim 9, characterized in that the compensation spring (8) acts directly on the lever (7).
Drive mechanism according to Claim 9, characterized in that the compensation spring (8) acts on the lever (7) via the overrun coupling (121).
Drive mechanism according to one or more of the preceding claims, characterized in that the actuation thereof takes place in a plane parallel to, and at a distance from, the arrangement of the switching units (106), the mechanism being provided for this purpose with a separate drive spindle (21), in that the switching crank (6) is situated in a plane through the centre line of the actuating spindle (1) and only makes contact with the lever (7) during switching-on after the instant at which the overturn point mechanism has passed through the overturn point, and in that the actuating spindle (1) is provided with a separate transmission crank (23) having two crank pins which are fitted offset with respect to each other at an angle which is at least as large as the angle through which the actuating spindle (1) rotates further after the overturn point mechanism has passed through the overturn point, and in that the drive spindle (21) is provided with a drive crank (22) which is designed to swing the one crank pin of the transmission crank (23) concomitantly in its one direction of rotation and to swing the other crank pin of the transmission crank (23) in its other direction of rotation, all this in a manner such that the space between the two crank pins forms an overrun space for the drive crank (22).
Drive mechanism according to one or more of the preceding claims, characterized in that the switch interacts with selection switches (261), in particular for making a connection between the switching units and earth or rail, and is provided for this purpose with a further drive spindle (29) which extends parallel to the drive spindle (21) and with a bridge (27) with which the selection switches (261) can be actuated simultaneously by the further drive spindle (29) and furthermore with locking means with which the actuation of the selection switches (261) is possible only with the switching units switched off.
Drive mechanism according to Claim 13, characterized in that the locking means comprising
- a locking slider (31) which can be slid parallel to the actuating spindle (1) and which blocks the actuation of the further drive spindle (29) as long as one of the levers (7) of the switching units (106) is in the switched-on state;

- a selection disc (25) which is adjustably arranged in a plane perpendicular to the drive spindles (21, 29) on a spindle (32) and which selection disc (25) is provided with an opening (24) through which only one of the drive spindles (21, 29) can always be actuated with the aid of an actuating key;

- a coupling fitted between the selection disc (25) and the locking slider (31),
all this in a manner such that the selection disc (25) can only be adjusted if the levers (7) are in the switched-off state and have released the blocking of the locking slider (31).
Drive mechanism according to Claim 14, characterized in that the coupling fitted between the selection disc (25) and the locking slider (31) is composed of a crank (33) which is attached to the spindle (32) and which interacts with a slot (312) in the locking slider (31) in a manner such that it is necessary to slide the locking slider (31) to adjust the selection disc (25) and the position of the locking slider (31) in the state of the selection disc (25) in which the drive spindle (21) can be actuated is the same as the state of the selection disc (25) in which the drive spindle (29) can be actuated.
Drive mechanism according to Claims 13, 14 or 15, characterized in that a locking pawl (34) is fitted on the locking slider (31) so as to interact with a locking disc (35) securely fitted on the drive spindle (29), the locking disc (35) being provided with one or more slots for receiving the locking pawl (34), all this in a manner such that the locking pawl (34) can drop into the slot (slots) only if the selection switch(es) is (are) correctly in one of the specified switching states, as a result of which the locking slider (31) with the locking pawl (34) can only then be slid and the selection disc (25) rotated in order to make the drive spindle (21) of the switching units capable of actuation.
Drive mechanism according to one or more of the preceding claims, characterized in that the drive mechanism interacts with at least one fuse which is provided with a striker pin (36) which emerges on blowing of the fuse, the actuating spindle (1) being provided with a blocking strip (28) for interaction with a locking lever (37) which can be actuated by the striker pin (36), all this in a manner such that, if the fuse is conductive, the locking lever (37) retains the blocking strip (38) in a state of the actuating spindle (1) in which the latter has already been rotated as a result of the rotation of the drive spindle (21) past the snap-through point in the switch-off direction but the switch-off pawls (13) still hold the levers (7) in the switched-on state and that, if the striker pin (36) emerges on blowing of the fuse, the locking lever (37) rotates so that the blocking strip (38) is released and the actuating spindle (1) is rotated further by the switch spring (5) and the switching units can be set to the off position.