WO2014198290A1

WO2014198290A1 - High-voltage switching device

Info

Publication number: WO2014198290A1
Application number: PCT/EP2013/061920
Authority: WO
Inventors: Lise Donzel; Jean-Claude Mauroux; Alexey Sokolov; Vittorio Gargioni
Original assignee: Abb Technology Ag
Priority date: 2013-06-10
Filing date: 2013-06-10
Publication date: 2014-12-18

Abstract

A high-voltage switching device (1) comprising: • at least a fixed contact (4) and an associated movable contact (3) which can be actuated between a closed position in which it is electrically coupled to fixed contact, and an open position in which it is electrically se separated from the fixed contact; • an actuating mechanism comprising at least a rotating cam (101); • a mechanical transmission unit operatively associated to the actuating mechanism and movable between a first operative position and a second operative position for actuating the movable contact (3) between the open position and the closed position. The mechanical transmission unit comprises at least a first rotating pin (120) operatively associated to the rotating cam (101) in such a way that an outer edge (103) of the rotating cam (101) slides on the first rotating pin (120) causing a first movement of the mechanical transmission unit from the first operative position to the second operative position, during a first rotation of the cam (101).

Description

"HIGH-VOLTAGE SWITCHING DEVICE"

The present invention relates to a high-voltage switching device, i.e. for applications with rated voltage above 1 kV.

As well known in the art, electric grids for transmitting and/or distributing power to various loads and users are equipped with various switching devices; such switching devices, typically current interrupters or circuit breakers, have the main task of properly protecting the grid in which they are used as well as various loads and equipment connected therewith from damages which may be caused for example by electrical faults, e.g. short circuits.

To this end, a typical switching device comprises at least one electrical phase with current interruption mechanisms constituted by a contact movable between a closed position, in which is electrically coupled to an associated fixed contact, and an open position in which is electrically separated from the fixed contact.

For example, a typical circuit breaker comprises an interruption chamber with current interruption mechanisms constituted by the movable contact and the associated fixed contact; when a fault occurs, the circuit breaker is opened by actuating the movable contact to electrically separate from the fixed contact, thus interrupting the flow of current.

Suitable actuating mechanisms cause the actuation of the movable contacts from the closed to the open position (causing the opening of the switching device for interrupting the current flowing) and from the open to the closed position (causing the closure of the switching device for allowing the current flowing).

According to known solutions, the actuating mechanism comprises a cam which can be rotated by driving means, such as an electrical motor or a spring-drive; the cam is operatively associated to a mechanical transmission unit which is adapted to convert the rotation of the cam into a corresponding translation of the movable contact, for electrically coupling to or separating from the fixed contact.

According to a first known solution illustrated for example in figure 1, the rotating cam 20 is inserted into a seat 23 defined in a cam-follower unit 21; the cam-follower unit 21 is operatively connected to the movable contact 35 of the switching device.

The cam 20 under rotation abuts against the internal walls of the cam-follower unit 21 which delimit the seat 23, in such a way to cause a linear displacement of the cam-follower unit 21 along guiding elements 22, such as rails or rods 22. The linear displacement of the cam-follower unit 21 causes the actuation of the movable contact 35. An example of such an actuating mechanism and associated mechanical transmission unit is disclosed in international patent application WO2010/026048.

The actuating mechanism and associated mechanical transmission unit according to this first known solution have relevant friction losses, mainly due to high friction forces generated between the rotating cam 20 and the internal walls of the seat 23, and between the sliding cam- follower unit 21 and the guiding elements 22.

For example, figure 2 is a graph depicting the results of a simulation related to the solution illustrated in figure 1, wherein the friction coefficient between the cam and cam-follower is set at 0.18, and the friction coefficient between the cam-follower and the guiding elements is set at 0.15. In particular, the graph of figure 2 shows how the main amount of generated drive energy 50 is dissipated into friction energy losses 51, and only the remaining amount results in a kinematic energy 52 for the actuating mechanism and the associated mechanical transmission unit.

According to a second known solution, the mechanical transmission unit comprises a pin inserted into a corresponding slot defined through the body of the rotating cam, so as the pin can slide onto the internal surfaces of the slot when the cam is under rotation. The sliding of the pin onto the internal surfaces of the slot causes a displacement of the overall mechanical transmission unit for actuating the associated movable contacts.

In particular, the pin is fixed on a mounting plate which can slide on corresponding guiding elements, such as rails, rods or a tube, due to the operative interaction between the pin and the slot of the cam under rotation. The sliding of the mounting plate onto the guiding elements causes a corresponding displacement of the mechanical transmission unit for actuating the movable contacts. An example of such actuating mechanism and associated mechanical transmission unit is disclosed in DE4006452.

Friction between the sliding mounting plate and the corresponding guiding elements and friction between the fixed pin and the corresponding slot involve relevant losses. Hence, the main amount of generated drive energy is dissipated into friction energy losses, and only the remaining amount results in a kinematic energy.

Alternatively, oscillating bearing means are connected to the mechanical transmission unit instead of the sliding mounting plate and the corresponding guiding elements; according to this solution, the pin inserted into the slot of the cam is a rotating pin which slides in turns to a lower internal surface or an upper internal surface of the slot, during the rotation of the cam. This causes a change of the rotational direction of the pin. An example of such actuating mechanism and associated mechanical transmission unit is disclosed in CN202008953.

The change of the rotational direction of the pin involves relevant friction losses; hence, also in this known solution the main amount of generated drive energy is dissipated into friction energy losses, and only the remaining amount results in a kinematic energy.

The high friction losses in all the above disclosed known solutions cause a waste of the energy generated by the driving means, and also wear of the components. In addition to reduce the operative life span of the actuating mechanism and the associated mechanical transmission unit, the wear of the components jeopardizes the workability of the switching device, namely considering its dielectric strength.

Furthermore, in the known solutions non-linear effects of the high friction losses cause back and forth oscillations in the main movement of the contact associated to the mechanical transmission unit. For example, the graph of figure 2 illustrates also the simulation results of the distance 53 between the movable contact 35 under actuation and the corresponding fixed contact. The illustrated distance 53 has oscillations 54 over time, meaning that the movement of the contact 35 presents oscillations.

In light of above, at the current state of the art, although known solutions perform in a rather satisfying way, there is still reason and desire for further improvements.

Such desire is fulfilled by a high- voltage switching device comprising:

- at least a fixed contact and an associated movable contact which can be actuated between a closed position in which the movable contact and the fixed contact are electrically coupled, and an open position in which the movable contact and the fixed contact are electrically separated;

- an actuating mechanism comprising at least a rotating cam;

- a mechanical transmission unit operatively associated to the actuating mechanism and movable between a first operative position and a second operative position for actuating the movable contact between the open position and the closed position.

The mechanical transmission unit comprises at least a first rotating pin operatively associated to the rotating cam in such a way that an outer edge of the rotating cam slides on the first rotating pin causing a first movement of the mechanical transmission unit from the first operative position to the second operative position, during a first rotation of the cam.

Further characteristics and advantages will become apparent from the description of preferred but not exclusive exemplary embodiments of an actuating mechanism and associated mechanical transmission unit of a high-voltage switching device according to the present disclosure, illustrated only for non-limitative exemplary purposes in the accompanying drawings, wherein: figure 1 shows an actuating mechanism and an associated mechanical transmission unit according to a solution known in the state of the art;

- figure 2 is a graph illustrating the simulation results of the energy balance and the contact distance over time related to the solution illustrated in figure 1 ;

figure 3 is a lateral view of a switching device according to the present disclosure;

figure 4 is a lateral view of a first exemplary actuating mechanism and associated mechanical transmission unit, wherein such mechanical transmission unit is operatively connected to a movable contact of a switching device according to the present disclosure and illustrated in two operative positions.

figures 5 and 6 are a perspective view and a section perspective view, respectively, of a part of the first actuating mechanism and associated mechanical transmission unit illustrated in figure 4;

- figure 7 is a perspective view of a rotating cam adapted to be used in the first actuating mechanism illustrated in figure 4, also showing a driving shaft associated to such rotating cam; figure 8 is a graph illustrating a target motion of a mechanical transmission unit according to the present disclosure over the angle of rotation of the associated rotating cam, and first and second derivatives for such target motion;

- figure 9 is a graph illustrating the simulated energy balance and the contact distance over time related to the first actuating mechanism and associated mechanical transmission unit illustrated in figure 4;

figure 10 is a lateral view of a second exemplary actuating mechanism and associated mechanical transmission unit, wherein such mechanical transmission unit is operatively connected to a movable contact of a switching device according to the present disclosure and illustrated in two operative positions; figure 11 is a section lateral view of at least a part of the second actuating mechanism and associated mechanical transmission unit illustrated in figure 10;

figure 12 is a perspective view of at least a part of a third exemplary actuating mechanism and associated mechanical transmission unit for a switching device according to the present disclosure; and

figure 13 is a perspective view of a rotating cam adapted for being used in the second actuating mechanism illustrated in figure 10 or in the third actuating mechanism illustrated in figure 12.

It should be noted that in the detailed description that follows, identical or similar components, either from a structural and/or functional point of view, have the same reference numerals, regardless of whether they are shown in different embodiments; it should also be noted that in order to clearly and concisely describe the present invention, the drawings may not necessarily be to scale and certain features of the disclosure may be shown in somewhat schematic form. Further, when the term "adapted" (shaped/configured/etc...) is used herein while referring to any component as a whole, or to any part of a component, or to a whole combinations of components, or even to any part of a combination of components, it has to be understood that it means and encompasses the structure, and/or configuration and/or shape and/or positioning of the related component or part thereof, or combinations of components or part thereof, such term refers to.

With reference to the above cited figures, the high-voltage switching device according to the present disclosure, indicated by the overall reference 1, comprises at least a fixed contact 4 and an associated movable contact 3, wherein the movable contact 3 can be actuated between a closed position in which the movable contact 3 and the fixed contact 4 are electrically coupled for allowing a current flowing therethrough, and an open position in which the movable contact 3 and the fixed contact 4 are electrically separated.

In the exemplary embodiment illustrated in figure 3 the switching device 1 comprises an outer casing 10; the casing 10 can be preferably a metal-clad casing 10, i.e. it is electrically conducting and can be connected to ground potential, or alternatively it can be a live tank or casing.

The casing 10 houses interruption mechanisms comprising at least one movable contact 3 and the associated fixed contact 4. For example, each couple of movable and fixed contacts 3, 4 is positioned into a respective vacuum or gas filled chamber defined inside the casing 10. Further, in the exemplary embodiment illustrated in figure 3 the casing 10 is connected for instance to two bushings 11 each housing a respective conductor, e.g. a bar or rod; such conductors are operatively connected to the interruption mechanisms housed into the casing 10. In practice, the conductors associated to the bushings 11 and related connections between them and with the interruption mechanisms allow to realize input/output electrical connections of the switching device 1, for example with an external power line, with the current flowing through the interruption mechanisms according to solutions well known or readily available to those skilled in the art, and therefore not described herein in details.

The switching device 1 according to the present disclosure comprises an actuating mechanism and a mechanical transmission unit.

The mechanical transmission unit is movable between a first operative position and a second operative position for actuating the movable contact 3 between the open position and the closed position.

The actuating mechanism is operatively associated to the mechanical transmission unit for causing its movement between the first and second operative positions. In practice, the actuating mechanism is adapted to drive the movement of the associated mechanical transmission unit between the first and second operative positions, for actuating the movable contact 3 between the open and closed positions.

With reference to the exemplary embodiments illustrated in figures 4-6, 10-11 and 12, the actuating mechanism of the switching device 1 comprises at least a rotating cam 101 which can rotate about an axis of rotation 102.

Advantageously, the mechanical transmission unit comprises at least a first rotating pin 120 operatively associated to the rotating cam 101 in such a way that the outer edge 103 of the rotating cam 101, i.e. the delimiting edge 103 of the shaped body of the cam 101, slides on the first rotating pin 120 causing a movement of mechanical transmission unit from the first operative position to the second operative position, during a first rotation of the cam 101 about the axis of rotation 102.

For sake of simplicity the term "first movement" will be used hereinafter to indicate the above mentioned movement of the mechanical transmission unit from the first operative position to the second operative position, which is caused by the sliding of the outer edge 103 of the cam 101 under rotation onto the first rotating pin 120. In practice, the outer edge 103 of the rotating cam 101 is adapted to slide on the first rotating pin 120, during the first rotation of the cam 101, pushing the overall mechanical transmission unit from its first operative position to its second operative position and, hence, causing a corresponding actuation of the movable contact 3. In this way, the mechanical transmission unit converts the first rotation of the cam 101 into a corresponding actuation of the movable contact 3, by means of the operatively interaction between its first rotating pin 120 and the outer edge 103 of the rotating cam 101.

According to the exemplary embodiments illustrated in figures 4-6, 10-11 and 12, the mechanical transmission unit of the switching device 1 comprises at least an element 110 having two spaced facing walls 111. The first rotating pin 120 is operatively connected to the element 110 so as to extend between the facing walls 111, and the rotating cam 101 is inserted between the facing walls 111 in such a way to be operatively associated to the first rotating pin 120 according to the above disclosure.

Preferably, the first rotating pin 120 is operatively connected to the facing walls 111 by means of needle bearings 123. For example, as illustrated in the embodiments of figures 4-6, 10-11 and 12, the first rotating pin 120 is inserted through corresponding holes defined aligned to each other in the facing walls 111, and the needle bearings 123 are interposed between the first rotating pin 120 and the internal surfaces of the corresponding holes. In particular, the first rotating pin 120 passes through the corresponding holes so to extend between the facing walls 111 and have opposed ends 130 (only one of which viewable in the cited figures) which extend outward from the element 110.

The element 110 is operatively connected to the movable contact 3 to cause its actuation between the open position and the closed position when the mechanical transmission unit is moving between the first operative position and the second operative position. In the exemplary embodiments illustrated in figures 4-6, 10-11 and 12, the mechanical transmission unit comprises a rod 200, preferably made of insulating material, which operatively connects the element 10 to the movable contact 3; for example, the rod 200 is connected to the element 110 by means of a connecting pin 202.

A contact closing spring can be interposed between the rod 200 and the movable contact 3 for guaranteeing an adequate contact pressure between the fixed contact 4 and the movable contact 3 in the closed position, according to a solution well known in the art and therefore not further disclosed.

Preferably, as illustrated in the exemplary embodiments of figures 4-6, 10-11 and 12, the switching device 1 comprises at least a pair of first oscillating links, or levers, 500 which can oscillate about an axis indicated with numeral reference 600. For example, the switching device 1 comprises a supporting element 700 which is adapted for being fixedly connected to one or more corresponding parts of the switching device 1, wherein the oscillating links 500 are operatively connected to the supporting element 700 so as to be able of oscillating about the axis 600.

The oscillating links 500 are operatively connected to the first rotating pin 120, so as to bear the mechanical transmission unit and guide, through their oscillation about the axis 600, the movement of such mechanical transmission unit between the first and second operative positions. Preferably, the oscillating links 500 are operatively connected to the rotating pin 120 by means of needle bearings 900.

In the exemplary embodiments illustrated in figures 4-6, 10-11 and 12, each of the oscillating links 500 has a lower end operatively connected to a corresponding end 130 of the first rotating pin 120 by the needle bearings 900, and an upper end operatively connected to the support element 700 by means of a rotating pin 650; in this way, each of the oscillating links 500 can oscillate about the axis 600 which is defined by the rotating pin 650.

Preferably, the rotating pin 650 is operatively connected to the supporting element 700 by means of needle bearings 750.

Preferably, the mechanical transmission unit of the switching device 1 further comprises a second rotating pin 121, and the rotating cam 101 is disposed between the first and second rotating pins 120, 121.

According to the exemplary embodiments illustrated in figures 4-6, 10-11 and 12, the second rotating pin 121 is operatively connected to the element 110 so as to extend between the facing walls 111.

Preferably, the second rotating pin 121 is operatively connected to the facing walls 111 by means of needle bearings 123. For example, the second rotating pin 121 is inserted through corresponding holes defined aligned to each other in the facing walls 111 and the needle bearings 123 are interposed between the second rotating pin 121 and the internal surfaces of such holes. In particular, the second rotating pin 121 passes through the corresponding holes so to extend between the facing walls 111 and have opposed ends 131 (only one of which viewable in the cited figures) which extend outward from the element 110.

Preferably, as illustrated in the exemplary embodiments of figures 4-6, 10-11 and 12, the switching device 1 comprises one or more second oscillating links, or levers, 501 which can oscillate about an axis indicated with numeral reference 601. For example, the one or more oscillating links 501 are operatively connected to the supporting element 700 of the switching device 1, so as to be able of oscillating about the axis 601.

In particular, the one or more oscillating links 501 are operatively connected to the second rotating pin 121, so as to bear the mechanical transmission unit and guide, through their oscillation about the axis 601, the movement of such mechanical transmission unit between the first and second operative positions. Preferably, the one or more oscillating links 501 are operatively connected to the second rotating pin 121 by means of needle bearings 901.

Preferably, the one or more oscillating links 501 have substantially the same length of the oscillating links 500.

In the exemplary embodiments illustrated in figures 4-6 and 10-11, the switching device 1 comprises a pair of oscillating links 501 having a lower end operatively connected to a corresponding one of the ends 131 of the second rotating pin 121 by means of the needle bearings 901. In the exemplary embodiment illustrated in figure 12, the switching device 1 comprises a single link 501 having a lower end operatively connected by means of needle bearings 901 to a central portion of the second rotating pin 121 which extends between the facing walls 111 of the element 110.

The upper end of the two links 501 illustrated in figures 4-6 and 10-11 and of the single link 501 illustrated in figure 12 is operatively connected to the support element 700 by means of a rotating pin 651; in this way, the oscillating link 501 can oscillate about its axis 601 which is defined by the rotating pin 651. Preferably, the rotating pin 651 is operatively connected to the supporting element 700 by means of needle bearings 751.

According to the exemplary embodiment illustrated in figures 4-6, 10-11 and 12, a driving shaft 300 is associated to the rotating cam 101. The driving shaft 300 is adapted to be operatively connected to driving means of the actuating mechanism of the switching device 1, such as an electrical motor or a spring-drive; in particular, the driving means are adapted for to transmit a torque to the cam 101 for causing its required rotation about the axis 102. At least a portion of the driving shaft 300 is inserted into a corresponding slot 302 defined in the mechanical transmission unit, so as to be accessible by the driving means for rotating the cam 101.

The slot 302 is defined in such a way to allow the movement of the mechanical transmission unit relative to the rotating cam 101 and its driving shaft 300. In particular, the slot 302 is defined so as its internal surfaces do not contact the driving shaft 300 during the movement of the mechanical transmission unit between the first and second operative positions.

In the exemplary embodiments illustrated in figures 7 and 13, the driving shaft 300 has two portions 301a and 301b which protrude transversally from a first side 312 and a second opposed side (not viewable in cited figures) of the rotating cam 101, respectively.

Accordingly, as illustrated in the exemplary embodiments of figures 4-6, 10-11 and 12, the element 110 comprises a first slot 302 defined in one of the two facing walls 111 for receiving therethrough the portion 301a of the driving shaft 300, and a second slot (not viewable in the cited figures) defined in the other of the two facing walls 111 for receiving therethrough the portion 301b of the driving shaft 300.

The first slot 302 and the second slot are defined in the corresponding facing walls 111 between the rotating pins 120 and 121.

According to the exemplary embodiment illustrated in figures 4-6, the rotating cam 101 disposed between the first and second rotating pins 120, 121 is operatively associated also to the second rotating pin 121, in such a way that its outer edge 103 slides on the second rotating pin 121 causing a movement of the mechanical transmission unit from the second operative position to the first operative position, during a second rotation of the cam 101.

For sake of simplicity the term "second movement" will be used hereinafter to indicate the above mentioned movement of the mechanical transmission unit from the second operative position to the first operative position.

The second rotation of the cam 101 about the axis of rotation 102 is opposed to the first rotation for causing the first movement of the mechanical transmission unit, meaning that the second rotation occurs according to a rotational direction which is opposed to the rotational direction of the first rotation.

In practice, the outer edge 103 of the rotating cam 101 is adapted to slide on the second rotating pin 121, during the second rotation of the cam 101, pushing the overall mechanical transmission unit from its second operative position to its first operative position and, hence, causing a corresponding actuation of the movable contact 3. In this way, the mechanical transmission unit converts the second rotation of the cam 101 into a corresponding actuation of the movable contact 3, by means of the operatively interaction between its second rotating pin 121 and the outer edge 103 of the rotating cam 101.

For sake of simplicity, the actuating mechanism and associated mechanical transmission unit according to the exemplary embodiment illustrated in figures 4-6 are further disclosed by making particular reference to the lateral view illustrated in figure 4, where the above mentioned first movement of the mechanical transmission unit causes the actuation of the movable contact 3 from the open position to the closed position, the above mentioned second movement of the mechanical transmission unit causes the actuation of the movable contact 3 from the closed position to the open position, and the above mentioned first rotation and second opposed rotation of the rotating cam 101 are a clockwise rotation and a counterclockwise rotation, respectively. In particular, the outer edge 103 of the cam 101 is adapted to slide on the first rotating pin 120, during the clockwise rotation of the cam 101 about the axis of rotation 102, pushing the overall mechanical transmission unit from its first operative position (illustrated for exemplary purpose in the lower part of figure 4) towards the fixed contact 4, so as to reach the second operative position (illustrated for exemplary purpose in the upper part of figure 4) where the movable contact 3 is in closed position with respect to the fixed contact 4.

The sliding of the outer edge 103 on the first rotating pin 120 causes a counterclockwise rotation of the pin 120 itself, when the cam 101 is rotating clockwise; advantageously, during the overall first movement of the mechanical transmission unit, the pin 120 is caused by the outer edge 103 of the cam 101 to rotate always according to the same counterclockwise rotational direction. With reference to the exemplary embodiment illustrated in figures 4-7, the cam 101 is shaped in such a way that its outer edge 103 is also able to slide on the second rotating pin 121, during the clockwise rotation of the cam 101 about the axis of rotation 102; in particular, during the first movement of the mechanical transmission unit the second rotating pin 121 remains in contact to the outer edge 103, following the profile of the cam 101 under clockwise rotation.

In particular, the sliding of the outer edge 103 on the second rotating pin 121 causes a corresponding counterclockwise rotation of the pin 121 itself, when the cam 101 is rotating clockwise; advantageously, during the overall first movement of the mechanical transmission unit, the second rotating pin 121 it is caused by the outer edge 103 of the cam 101 to rotate always according to the same counterclockwise rotational direction.

Regarding the actuation of the movable contact 3 from the closed position to the open position, the outer edge 103 of the cam 101 is adapted to slide on the second rotating pin 121, when the cam 101 is rotating counterclockwise about the axis of rotation 102, pushing the overall mechanical transmission unit from its second operative position towards its first operative position where the movable contact 3 is in open position with respect to the fixed contact 4. The sliding of the outer edge 103 on the second rotating pin 121 causes a clockwise rotation of the pin 121 itself, when the cam 101 is rotating counterclockwise; advantageously, during the overall second movement of the mechanical transmission, the second rotating pin 121 is caused by the outer edge 103 of the cam 101 to rotate always according to the same clockwise rotational direction.

Furthermore, the cam 101 is shaped in such a way that its outer edge 103 also slides on the first rotating pin 120, during the counterclockwise rotation of the cam 101 about the axis of rotation 102; in particular, during the second movement of the mechanical transmission unit the first rotating pin 120 remains in contact to the outer edge 103, following the profile of the cam 101 under counterclockwise rotation.

In particular, such sliding of the outer edge 103 on the first rotating pin 120 causes a corresponding clockwise rotation of the pin 120 itself, when the cam 101 is rotating counterclockwise; advantageously, during the overall second movement of the mechanical transmission unit, the first rotating pin 120 is caused by the outer edge 103 of the cam 101 to rotate always according to the same clockwise rotational direction.

According to a different solution with respect to the exemplary embodiment illustrated in figures 4-6, the actuating mechanism of the switching device 1 comprises at least one spring 100 for causing the second movement of the mechanical transmission unit.

It is to be set forth that, even if in the exemplary embodiments illustrated in figures 10-11 and figure 12 the mechanical transmission unit also comprises the second rotating pin 121, it is the spring 100 that actuates the second movement of the mechanical transmission unit, and not an interaction between the rotating cam 101 and the second rotating pin 121 as per the exemplary embodiment illustrated in figures 4-6.

Preferably, according to the above mentioned different solution, the rotating cam 101 is shaped so as to remain in contact with the first rotating pin 120 while the mechanical transmission unit is in the second operative position, and to disengage from the first rotating pin 120 during a second rotation of the cam 101 around the axis of rotation 102; an example of such a rotating cam 101 is illustrated in figure 13.

The spring 100 is operatively associated to the mechanical transmission unit so as to cause the second movement of the mechanical transmission unit when the rotating cam 101 disengages from the first rotating pin 120.

According to the exemplary embodiment illustrated in figures 10-11 and to the exemplary embodiment illustrated in figure 12, the spring 100 is operatively associated to the mechanical transmission unit in such a way that:

- the first movement of the mechanical transmission unit causes a deformation of the spring 100 from a rest position to a deformed position;

- the mechanical transmission unit is hold in the second operative position by the rotating cam 101 in contact with the first rotating pin 120, so as to hold the spring 100 in the deformed position; and

- the spring 100 is able to return in the rest position when the rotating cam 101 disengages from said first rotating pin 120, for causing the second movement of the mechanical transmission unit.

In practice, the energy for actuating the second movement of the mechanical transmission unit is stored into the spring 100 during the first movement of the actuating mechanism (which is caused by the rotating cam 101); such energy is then released by the spring 100 to the mechanical transmission unit when the cam 101 disengages from the first rotating pin 120.

Hence, in order to actuate the second movement of the mechanical transmission unit, the driving means of the switching device 1 are used to rotate the cam 101 only to disengage from the first rotating pin 120.

Advantageously, the switching device 1 can comprise damping means 1000 which are adapted to operatively interact with the mechanical transmission unit moving from the second operative position to the first operative position, so as to avoid, or at least limit, a collision between the rotating cam 101 and the rotating pin 120 of the mechanical transmission unit under motion. According to the exemplary embodiment illustrated in figures 4-6, the switching device 1 comprises a casing 950 which houses the spring 100, and the mechanical transmission unit comprises a plunger 951 movable into the casing 950 for causing the deformation of the spring 100 from the rest position to the compressed position, during the first movement of the mechanical transmission unit.

For sake of simplicity the actuating mechanism and associated mechanical transmission unit according to the embodiment illustrated in figures 10-11 are further disclosed by making reference to the lateral view illustrated in figure 10, where the above mentioned first movement of the mechanical transmission unit causes the actuation of the movable contact 3 from the open position to the closed position, the above mentioned second movement of the mechanical transmission unit causes the actuation of the movable contact 3 from the closed position to the open position, and the above mentioned first rotation of the cam 101 is a clockwise rotation about the axis of rotation 102.

In particular, the outer edge 103 of the cam 101 is adapted to slide on the first rotating pin 120, during the first clockwise rotation of the cam 101 about the axis of rotation 102, pushing the overall mechanical transmission unit from its first operative position (illustrated for exemplary purpose in the lower part of figure 10) towards the fixed contact 4, so as to reach the second operative position (illustrated for exemplary purpose in the upper part of figure 10) where the first clockwise rotation of the cam 101 is stopped and the movable contact 3 is in closed position with respect to the fixed contact 4.

The sliding of the outer edge 103 on the first rotating pin 120 causes a counterclockwise rotation of the pin 120 itself; advantageously, during the overall first movement of the mechanical transmission unit, the first rotating pin 120 is caused by the outer edge 103 of the cam 101 to rotate always according to the same counterclockwise rotational direction.

The cam 101 is shaped to as to remain in contact to the first rotating pin 120 at the end of the first clockwise rotation.

The plunger 951 for deforming the spring 100 is operatively connected to the element 110 of the mechanical transmission unit and comprises a head 952. The casing 950 is fixed to one or more corresponding parts of the switching device 1 and comprises a base wall 953; the plunger 951 is inserted movable into the casing 950 through a hole 954 defined in the base wall 953, in such a way that its head 952 can move towards the base wall 953 during the first movement of the mechanical transmission unit, and away from the base wall 953 during the second movement of mechanical transmission unit. The spring 100 is placed into the casing 950 between the base wall 953 and the head 952 of the plunger 951, in such a way to be compressed by the head 952 of the plunger 951 during the first movement of the mechanical transmission unit.

Regarding the actuation of the movable contact 3 from the closed position to the open position, the cam 101 illustrated in figure 10 is shaped so as to disengage the first rotating pin 120, when it is further rotated clockwise around the axis of rotation 102, starting from its position assumed at the end of the first clockwise rotation.

Preferably, as soon as the rotating cam 101 disengages from the first rotating pin 120, its clockwise rotation is stopped.

The disengagement of the rotating cam 101 from the first rotating pin 120 causes the releasing of the spring 100 for pushing the head 952 of the plunger 951. This pushing is suitable to cause the second movement of the overall mechanical transmission to return in the first operative position, where the movable contact 3 is in open position with respect to the fixed contact 4.

Furthermore, the damping means 1000 are fixed to one or more corresponding parts of the switching device 1 so as to intercept the head 952 of the plunger 951 and stop the second movement of the mechanical transmission unit caused by the spring 100.

Alternatively with respect to the exemplary embodiment illustrated in figures 10-11, the spring 100 can be a torsion spring 100 or a clock spring 100 which is operatively associated to at least one oscillating element 501 of the switching device 100 which is adapted to oscillate about an axis of oscillation 601.

In particular:

- the oscillating element 501 is operatively connected to the mechanical transmission unit so as to oscillate about the axis 601 when the mechanical transmission unit is moving between the first and second operative positions; and

- the torsion or clock spring 100 is operatively associated to the oscillating element 501 so as to be twisted by an oscillation of the element 501, oscillation which is caused by the first movement of the mechanical transmission unit.

In the exemplary embodiment illustrated in figure 12, the oscillating element is the link 501 operatively connected to the second rotating pin 121 and to the rotating pin 651. In particular, the torsion or clock spring 100 (schematically depicted by dot lines in figure 12) is mounted around the rotating pin 651, in such a way to be twisted by the rotation of the rotating pin 651, rotation which in turn is caused by the oscillation of the link 501 due to the first movement of the mechanical transmission unit.

When the rotating cam 101 disengages from the first rotating pin 120 of the mechanical transmission unit in the second operative position, the torsion or clock 100 spring is released to return in the rest position; such releasing causes a rotation of the rotating pin 651 which drives the oscillation of the link 501 and the corresponding return of the mechanical transmission unit in the first operative position.

The rotating cam 101 of the actuating mechanism of the switching device 1 according to the present disclosure is advantageously shaped in such a way that the values of the first and second derivatives of the position of the mechanical transmission unit over the angle of rotation of the cam 101 are substantially equal to zero at the start and at the end of at least one of the first and second movements of the mechanical transmission unit which are caused by the rotating cam 101 itself.

In particular, in the exemplary embodiment illustrated in figures 4-6 the rotating cam 101 is shaped in such a way that the values of the first and second derivatives are substantially equal to zero at the start and at the end of the first movement of the mechanical transmission unit caused by the first rotation of the cam 101, as well as at the start and at the end of the second movement of the mechanical transmission unit caused by the second opposed rotation of the cam 101.

In the exemplary embodiment illustrated in figure 10, the rotating can 101 is shaped in such a way that the values of the first and second derivatives are substantially equal to zero at the start and at the end of the first movement of the mechanical transmission unit caused by the first rotation of the cam 101.

For example, the graph of figure 8 illustrates a target position 800, i.e. a spatial coordinate 800, of a connecting pin 201 of the mechanical transmission unit over the values of the angle of rotation of the cam 101, together with the target first and second derivatives 801 and 802 of such position 800 over the angle of rotation.

In particular, the first and second target derivatives 801 and 802 have both a zero value at the start and at the end of the movement of the mechanical transmission unit caused by the rotation of the cam 101.

It is to be set forth that even if the position 800 illustrated in figure 10 is in particular related to the position of the connecting pin 201, curves with the same behavior of the illustrated curves 800, 801, 802 will be obtained considering the position over the angle of rotation of other different parts of the mechanical transmission unit.

The rotating cam 101 is designed so as to obtain the target first and second derivatives 801 and 802 for the motion of the mechanical transmission unit over the angle of rotation of the cam 101. The operation of the actuating mechanism and associated mechanical transmission unit of the switching device 1 according to the present disclosure is described in the following description, by making particular reference to the exemplary embodiments illustrated in figures 4-6, 10-11 and 12.

With reference to the exemplary embodiment illustrated in figure 4, it is considered a starting situation wherein the movable contact 3 is in the open position with respect to the fixed contact 4, and the mechanical transmission unit is in its first operative position

In order to actuate the movable contact 3 from the open position to the closed position, the driving means of the switching device 1 act on the driving shaft 300 causing a clockwise rotation of the cam 101.

The outer edge 103 of the cam 101 under clockwise rotation slides onto the first and second rotating pins 120 and 121 causing a counterclockwise rotation thereof; in particular the sliding outer edge 103 pushes progressively the first rotating pin 120, and hence the overall mechanical transmission unit, towards the fixed contact 4, until the mechanical transmission unit reaches its second operative position where the clockwise rotation of the cam 101 is stopped and the movable contact 3 is in the closed position with respect to the fixed contact 4.

The slots 102 defined in the element 110 of the mechanical transmission units allow the movement of the element 110 relative to the cam 101 and the driving shaft 300 which are under rotation about the fixed axis of rotation 102.

The first movement of the mechanical transmission is guided by the oscillating links 500 and the oscillating links 501 which oscillate clockwise about the axis 600 and the axis 601, respectively. In order to cause the return of the movable contact 3 to its open position, the driving means of the switching device 1 act on the driving shaft 300 to cause a counterclockwise rotation of the cam 101.

The outer edge 103 of the cam 101 under counterclockwise rotation slides onto the first and second rotating pins 120 and 121, causing a clockwise rotation thereof; in particular the sliding outer edge 103 pushes progressively the second rotating pin 121, and hence the overall mechanical transmission unit towards the first operative position where the counterclockwise rotation of the cam 101 is stopped.

The second movement of the mechanical transmission unit is also guided by the oscillating links 500 and 501 which oscillate counterclockwise about the axis 600 and 601, respectively.

With reference to the exemplary embodiment illustrated in figure 10, it is considered a starting situation wherein the movable contact 3 is in the open position with respect to the fixed contact 4, and the mechanical transmission unit is in its first operative position

In order to actuate the movable contact 3 from the open position to the closed position, the driving means of the switching device 1 act on the driving shaft 300 causing a first clockwise rotation of the cam 101. The outer edge 103 of the cam 101 under clockwise rotation slides only onto the first rotating pin 120 causing a counterclockwise rotation thereof; in particular the sliding outer edge 103 pushes progressively the first rotating pin 120, and hence the overall mechanical transmission unit, towards the fixed contact 4, until the mechanical transmission unit reaches its second operative position where the clockwise rotation of the cam 101 is stopped and the movable contact 3 is in the closed position with respect to the fixed contact 4.

The first movement of the mechanical transmission is guided by the oscillating links 500 and the oscillating links 501 which oscillate clockwise about the axis 600 and 601, respectively.

This first movement causes the compression of the spring 100 housed in the casing 952 by means of the plunger 951. Alternatively, with reference to the exemplary embodiment illustrated in figure 12, the first movement of the mechanical transmission unit can twist the torsion or clock spring 100 by means of the rotation of the rotating pin 651, rotation which is caused by the oscillation of the link 501.

When the mechanical transmission unit is in the second operative position, the rotating cam 101 is still in contact to the first rotating pin 120 and holds the mechanical transmission unit in such second operative position and the spring 100 in the deformed position.

In order to cause the return of the movable contact 3 to its open position, the driving means of the switching device 1 act on the driving shaft 300 to cause a second clockwise rotation of the cam 101 about the axis of rotation 102. In particular, during this second rotation the cam 101 is rotated only until it disengages from the first rotating pin 120, and then it is stopped. The disengagement of the rotating cam 101 from the first rotating pin 120 causes the release of the spring 100 and the return of the mechanical transmission unit in the first operative position. The second movement of the mechanical transmission unit is also guided by the oscillating links 500 and the oscillating links 501 which oscillate counterclockwise about the axis 600 and 601, respectively.

In particular, the release of the compressed spring 100 into the housing 950 pushes the plunger 951 and hence the overall mechanical transmission unit towards the first operative position, where the movable contact 3 is in the open position with respect the fixed contact 4.

Alternatively, with reference the exemplary embodiment illustrated in figure 12, the release of the torsion or clock spring 100 causes the counterclockwise oscillation of the link 501 about its axis 601; such oscillation of the link 501 causing the return of the mechanical transmission unit from the second operative position to the first operative position.

In practice, it has been seen how the switching device 1 according to the present disclosure allows achieving the intended object offering some improvements over known solutions.

In particular, the actuating mechanism has reduced friction losses with respect to known solution. This is mainly due to the devised operatively interaction between the outer edge 103 of the rotating cam 101 and the first rotating pin 120 for causing the first movement of the mechanical transmission unit, according to which the first rotating pins 120 can rotate without significant friction losses, in particular without changing its rotational direction during the overall first movement of the mechanical transmission unit.

In the exemplary embodiment illustrated in figures 4-6, also the devised operatively interaction between the outer edge 103 of the rotating cam 101 and the second rotating pin 121 for causing the second movement of the mechanical transmission unit allows a rotation of such pin 121 without significant friction losses, in particular without changing its rotational direction during the overall second movement of the mechanical transmission unit.

In the exemplary embodiments illustrated in figures 10-11 and 12, the second movement of the mechanical transmission unit does not involve is not caused by a contact between the rotating cam 101 and the first and second rotating pins 120, 121, thus reducing the friction losses. Furthermore, the energy for causing the second movement of the mechanical transmission unit is stored in the spring 100 during its deformation caused by the first movement, without requiring the intervention of the driving means associated to the rotating cam 101.

Oscillating links 500, 501 can be used to further reduce the friction losses, because they support the rotating pins 120, 121 and, hence, reduce the friction between such pins 120, 121 with other components or elements, such as the rotating cam 101 or the element 110 of the mechanical transmission unit.

Furthermore, the oscillating links 500, 501 avoids the use in the actuating mechanism of parts sliding on corresponding guiding rails, rods, tubes, et cetera.

Needle bearings 123 can be used to further reduce friction losses between the first and second rotating pins 120 and 121 and the facing walls 111 of the element 110; needle bearings 900 reduce friction losses between oscillating links 500 and the rotating pin 120; needle bearings 901 reduce friction losses between oscillating links 501 and the rotating pin 121; and needle bearings 750 and 751 reduce friction losses between the rotating pins 650 and 651 and the supporting element 700.

For example, figure 9 shows a graph depicting the results of a simulation related to the energy balance of the actuating mechanism and associated mechanical transmission unit illustrated in figures 4-6, wherein the friction coefficient between the rotating cam 101 and the first and second rotating pins 120, 121 is set at 0.18, and wherein the friction in the needle bearings have been considered negligible.

In particular, the graph of figure 9 shows how the main amount of the drive energy 850 generated by the driving means of the switching device 1 results in a kinematic energy 851 of the actuating mechanism and associated mechanical transmission unit, while only the remaining small amount results in energy dissipated 852 by frictions.

Furthermore, the graph of figure 9 illustrates the simulation results related to the distance 853 between the movable contact 3 under actuation and the fixed contact 4; in particular, there are no oscillations over time in the curve 853, meaning that the contact 3 advantageously moves smoothly relative to the fixed contact 4, without or at least with limited oscillations.

With reference to figure 8, the fact that the rotating cam 101 is designed according to the first and second target derivatives 801, 802 implies the following advantageous effects:

- the movable contact 3 is kept in the open position or in the closed without requiring a mechanical moment from the driving means associated to the rotating cam 101;

- the effect of impacts of the first rotating pins 120 on the cam 110 is minimized, mainly do the fact that the second derivative 802 is continuous;

- smooth start and termination of the motion of the movable contact 3; and

- adequate functioning of the actuating mechanism and associated mechanical transmission unit, when unexpected disturbances are present.

The switching device 1 thus conceived is also susceptible of modifications and variations, all of which are within the scope of the inventive concept as defined in particular by the appended claims.

For example, any possible combination of the previously disclosed embodiments can be implemented and has to be considered within the inventive concept of the present disclosure; all the details may furthermore be replaced with technically equivalent elements.

For example, some of the previously described components may be differently shaped, or used in a different number of parts or elements, or the components previously described can be differently connected with respect to each other.

For example, even if in the exemplary embodiments illustrated in figures 10-11 and 12 the outer edge 103 of the rotating cam 101 operatively interacts with the first rotating pin 120 to actuate the movable contact from the open position to the closed position while the spring 100 is used to actuate the movable contact 3 from the closed position to the open position, the actuating mechanism and associated mechanical transmission unit can be configured so as the outer edge 103 of the rotating cam 101 operatively interacts with the second rotating pin 121 to cause the actuation of the movable contact 3 from the closed position to the open position while the spring 100 is used to actuate the movable contact 3 from the open position to the closed position.

Also the materials used, so long as they are compatible with the specific use and purpose, as well as the dimensions, may be any according to the requirements and the state of the art

Claims

1. A high- voltage switching device (1) comprising:

at least a fixed contact (4) and an associated movable contact (3) which can be actuated between a closed position in which the movable contact and the fixed contact are electrically coupled, and an open position in which the movable contact and the fixed contact are electrically separated;

an actuating mechanism comprising at least a rotating cam (101);

a mechanical transmission unit operatively associated to said actuating mechanism and movable between a first operative position and a second operative position for actuating the movable contact (3) between said open position and said closed position;

said high-voltage switching device (1) characterized in that said mechanical transmission unit comprises at least a first rotating pin (120) operatively associated to said rotating cam (101) in such a way that an outer edge (103) of the rotating cam (101) slides on said first rotating pin (120) causing a first movement of the mechanical transmission unit from the first operative position to the second operative position, during a first rotation of the cam (101).

2. The switching device (1) according to claim 1, wherein said mechanical transmission unit comprises a second rotating pin (121), and said rotating cam (101) is disposed between said first and second rotating pins (120, 121).

3. The switching device (1) according to claim 2, wherein said rotating cam (101) is operatively associated to said second rotating pin (121) in such a way that the outer edge (103) of the rotating cam (101) slides on the second rotating pin (121) causing a second movement of the mechanical transmission unit from the second operative position to the first operative position, during a second rotation of the cam (101) which is opposed with respect to said first rotation.

4. The switching device (1) according to claim 1 or claim 2, wherein said actuating mechanism comprises at least one spring (100) for causing a second movement of the mechanical transmission unit from the second operative position to the first operative position.

5. The switching device (1) according to claim 4, wherein: said rotating cam (101) is shaped so as to remain in contact with said first rotating pin (120) while the mechanical transmission unit is in the second operative position, and to disengage from said first rotating pin (120) during a second rotation of the cam; and

said at least one spring (100) is operatively associated to said mechanical transmission unit so as to cause said second movement of the mechanical transmission unit, when the cam (101) disengages from said first rotating pin (120).

6. The switching device (1) according to claim 5, wherein said at least one spring (100) is operatively associated to said mechanical transmission unit in such a way that:

said first movement of the mechanical transmission unit causes a deformation of said spring (100) from a rest position to a deformed position;

said mechanical transmission unit is hold in the second operative position by the rotating cam (101) in contact with the first rotating pin (120), so as to hold the spring (100) in the deformed position; and

the spring (100) is able to return in the rest position when the rotating cam (101) disengages from said first rotating pin (120), for causing said second movement of the mechanical transmission unit.

7. The switching device (1) according to claim 6, comprising a casing (950) which houses said at least one spring (100), wherein said mechanical transmission unit comprises a plunger (951) movable into said casing for causing said deformation of the spring (100) from the rest position to the deformed position.

8. The switching device (1) according to claim 6, comprising at least one oscillating element (501) which can oscillate about an axis of oscillation (601), wherein:

said at least one oscillating element (501) is operatively connected to the mechanical transmission unit so as to oscillate about the axis of oscillation (601) when the mechanical transmission unit is moving between said first and second operative positions; and

said at least one spring (100) comprises a torsion spring or a clock spring operatively associated to said at least one oscillating element (501) so as to be deformed from the rest position to the deformed position by the oscillation of the oscillating element (501) which is caused by the first movement of the mechanical transmission unit.

9. The switching device (1) according to one or more of claims 4-8, comprising damping means (1000) adapted to operatively interact with said mechanical transmission unit during said second movement.

10. The switching device (1) according to one or more of the preceding claims, wherein:

said mechanical transmission unit comprises an element (110) having two spaced facing walls (111);

said first rotating pin (120) is operatively connected to said element (110) so as to extend at least between said two facing walls (111); and

said rotating cam (101) is inserted between said two facing walls (111).

11. The switching device according to claim 10, wherein said second rotating pin (121) is operatively connected to said element (110) so as to extend at least between said two facing walls (111).

12. The switching device (1) according to claim 10 or claim 11 wherein said first rotating pin (120) is operatively connected to said element (110) by means of needle bearings (123).

13. The switching device (1) according to one or more of claims 10-12, wherein said second rotating pin (121) is operatively connected to said element (110) by means of needle bearings (123).

14. The switching device (1) according to one or more of the preceding claims, comprising a pair of first oscillating links (500) which are operatively connected to said first rotating pin (120).

15. The switching device (1) according to one or more of the preceding claims, comprising a at least one second oscillating link (501) which is operatively connected to said second rotating pin (121).

16. The switching device (1) according to one or more of the preceding claims, wherein a driving shaft (300) is associate to the rotating cam (101) and is adapted to be operatively connected to driving means for rotating the cam (101), and wherein at least a portion (301a, 301b) of the driving shaft (300) is inserted in a corresponding slot (302) defined in the mechanical transmission unit.

17. The switching device (1) according to one or more of the preceding claims, wherein said rotating cam (101) is shaped in such a way that the values of the first and second derivatives (801, 802) of the position (800) of the mechanical transmission unit over the angle of rotation of the rotating cam (101) are substantially equal to zero at the start and at the end of said first movement of the mechanical transmission unit.