Patent Description:
More specifically, but not exclusively, the invention relates to a contactor device for industrial and/or railways applications wherein, for instance, a high D. current must be switched on and off with high capacity of switching actions to control electric motors, lighting, heating, capacitor banks, thermal evaporators, and other electrical loads.

As it is well known in this specific technical filed, contactors are remotely controlled switches including an electromagnetic actuator that may be used in many industrial or railways applications wherein a high A. current must be switched on and off with relatively high frequencies switching actions.

Generally speaking, a contactor may be considered a switching device for high current and voltage applications, no matter which is the electric load to be driven.

Just to give an idea of the working conditions and the range of current values involved for these kind of contactors, it should be noted that these devices must be able to efficiently switch currents at least in the range between 400A to 1800A and under operating voltage ranges between <NUM> V and <NUM> V.

Those operating ranges may even be referred to a single pole of the contactor but in many applications, it is however necessary to provide a double or a three poles configuration.

A contactor of known structure normally include fixed contacts, movable contacts and at least a contactor coil. In normally open devices, when a sufficient starting current flows through the contactor coil, the contactor responds and turns on the loads connected in the load circuit.

To maintain the contactor in this state, a holding current must continuously flow through the contactor. After the holding current is switched off, the contactor drops out. The energy stored in the contactor coil is dissipated in a free-wheeling circuit or, better, in a quick and proper overvoltage protection, like a Varistor or a Transit.

Contactors of high quality and performance require an arc extinguishing portion, so-called arc chute portion, for properly extinction of the electric arc that may be generated in the high voltage portion of the switch where the movable contacts are provided.

For example, <CIT> relates to an improved contactor device for high current switching applications, in particular industrial or railways applications wherein a high D. current must be switched on and off, said contactor device including a switch base portion including electric switching means of a high voltage portion and an arc extinguishing portion covering said switching means.

<CIT> relates to a direct current switching apparatus having two arc extinguishing chambers located in a common transverse plane, one chamber being divided into separate laterally spaced portions disposed below the other chamber, a pair of spaced conductors each having a contact element and an arc runner extending from near the contact, the arc runners being curved and disposed in a convex mirror-image relationship to each other between the laterally spaced portions, distal ends of said arc runners providing a divergent path into the other chamber, a conductor disposed at outboard sides of the laterally spaced arc chamber portions cooperating with concave sides of the arc runners to provide divergent paths into the spaced arc chamber portions, power supply terminals connected to the respective spaced conductors, magnetic plates disposed in front and in back of the arc chambers having portions providing a magnetic path externally around the chambers, permanent magnets magnetically coupled to at least one of the magnetic plates providing a magnetic field in the plates and across the arc chambers in a forward direction, a movable contact movable normal to the forward direction into and out of bridging engagement with the stationary contact elements, and an electromagnetic drive motor disposed coextensive with the arc extinguishing chambers, coupled at a lower end to the movable contact.

<CIT> relates to an electromechanical circuit breaker intended to establish and break the current in a main circuit and comprising a fixed contact element and a moving contact element which in a first position are in electrical contact with each other for carrying the current of the main circuit, said moving contact element being adapted to be displaced to a second position in which it is separated from the fixed contact element so that the current in the main circuit is cut off. The circuit breaker is provided with a blow-out device comprising a magnetising coil traversed by a magnetising current for producing a magnetic field adapted to drive an arc generated by the separation of said two contact elements into an arc extinction means.

One of the main problems encountered in the manufacturing of the switching devices for high current and voltage applications is just the correct dimensioning of the arc extinguishing portion.

This design phase is particularly critical since the arc chute portion requires sometimes to be enlarged and expanded according to the version of the switching device; in other words, according to the operating current or voltage that the switching device must manage.

Moreover, the extinguishing phase of the electric arc is a real problem when the contactor is used for low current applications.

As a matter of fact, the contactors are generally designed to switch high currents and when the switched current is under a predetermined threshold, for instance of few Ampere only, the magnetic field generated in the blow-out coil is not sufficient to detour the electric arc toward the extinguishing chamber. Such a current which is not sufficient to detour the electric arc toward the extinguishing chamber is defined as a "low (switched) current". Such a current is also known as "critical current".

The technical problem underlying the present invention is that of providing an improved switching device or contactor for high current or high voltage switching applications having such structural and functional characteristics to allow a more efficient dissipation of the electric arc that may be generated during the opening or closure phase of the movable contacts thus conferring to the device higher arc extinguishing capabilities.

Another aim of the present invention is that of providing a switching device having a higher reliability and a longer operating life due to a higher efficiency in the turn off phase of the possible electric arc.

A further object of the present invention is that of providing a switching device that may be constructed with materials having reasonable industrial costs.

The solution idea at the basis of the present invention is that of providing hardware means able to blow out the electric arc when low currents are switched by the contactor.

These hardware means include magnetic elements positioned in the proximity of moving contacts of the contactor to generate a magnetic field sufficient to at least partially detour the electric arc and to extinguish the arc generated when low switched currents are involved. Advantageously, those magnetic elements are permanent magnets.

According to the present invention, the technical problem is solved by an improved switching device or contactor having high arc extinguishing capabilities and comprising, in a protective casing:.

Arc runners are provided over each corresponding moving contact in their open or rest position and said hardware means including magnetic elements are positioned at both sides of each arc runner.

Moreover, said magnetic elements are positioned at each lateral side of each moving contact.

Advantageously, said hardware means include magnetic elements positioned close to said moving contacts to generate a magnetic field sufficient to at least partially detour the electric arc when low switched currents are involved. More specifically, advantageously, said magnetic elements are permanent magnets.

It should be noted that each of said magnetic elements is advantageously structured as a disk supported laterally of a corresponding moving contact in a fixed position when the moving contacts are in the rest or open position. Advantageously, the contactor of the present invention includes at least four magnetic elements, two for each moving contact.

It is understood that, advantageously, said hardware means are active to detour the electric arc toward said top arc chute and they are mainly active when said low currents are not enough, when flowing through the blow out coil, to generate the proper electromagnetic force.

Each arc runner is advantageously formed by a flat metal plate extended over the corresponding moving contact and bent on both lateral sides with opposite flanges that partially and laterally protect the corresponding moving contact; said magnetic elements being positioned at both sides of said opposite flanges.

Further features and advantages of the switching or contactor device of the present invention will appear from the following description given by way of not limiting example with reference to the enclosed drawings figures.

With reference to the drawing figures, with <NUM> is globally and schematically shown a switching or contactor device realized according to the present invention.

In particular, but not exclusively, the contactor <NUM> is specifically provided for industrial or railways applications wherein, for instance, a high D. current must be switched on and off with high frequencies switching actions to control electric motors, lighting, heating, capacitor banks, thermal evaporators, and other electrical loads.

Just to give an idea of the working conditions and the range of current values involved for these kind of contactors, it should be noted that these devices must be able to efficiently switch currents at least in the range between 400A to 1800A and under operating voltage ranges between <NUM> V and <NUM> V. For instance, a LTX family of line contactors is structured to operate under high voltage rating, high thermal current and when high breaking capacity (up to <NUM> kV) are required.

Those operating ranges may even be referred to a single pole of the contactor. In many applications it is however necessary to provide a double pole configuration and/or a three poles configuration that may be obtained by coupling single poles side by side thanks to a modular single pole structure, even if not shown in the drawings.

In the following lines we will disclose just the structure of a single pole module, as the same principle is applied on each couple of moving contacts even installed in a bipolar or tripolar contactor.

The module presents an envelope or housing <NUM> protecting and covering all the moving portions of the contactor device <NUM>. The envelope <NUM> is made by a synthetic plastic material having a predetermined isolation coefficient and high coefficient of trace index CTI. Such an envelope <NUM> has a base flange <NUM> and includes an internal frame <NUM> supporting the various moving components of the contactor <NUM>.

It should be noted that fixed terminal power contacts <NUM> and <NUM> are provided for the contactor <NUM>. Those fixed contacts <NUM>, <NUM> are projecting on opposite lateral sides of the envelope <NUM>; however, other dispositions may be adopted.

Those terminal power contacts <NUM>, <NUM> are each associated to a corresponding internal moving contact <NUM>, <NUM> provided inside the contactor device <NUM>, as will be explained hereinafter. Advantageously, the creepage and clearance distances between the moving contacts <NUM> and <NUM> has been widely dimensioned for safe applications in polluted environments but the narrow outline of the envelope <NUM> is especially conceived for applications where space is a critical issue.

The contactor <NUM> of the present invention is structured to be used on electrical equipment working in presence of severe shocks and vibrations that normally occurs on-board of traction vehicles. However, nothing refrains from employing this kind of contactors <NUM> in all the applications wherein a high A. current must be switched on and off, for instance: line contactors, power switches or converters, traction motors, electromagnetic brakes and heating/air conditioning systems.

The contactor <NUM> comprises a switch base portion <NUM> and an upper arc extinguishing portion <NUM>. The innovative design (of LTX line) of the invention combines the traditional technology of the arc chute (ceramic fins) with a new blow out system. Ceramic arc chute enables to withstand the highest current ratings and the new blowout system guarantees a high reliability with critical currents.

The switch base portion <NUM> is common for each different modular contactor <NUM> and corresponds to the main structure of the envelope <NUM> while the upper arc extinguishing portion <NUM> may be considered as a top coverage of the envelope <NUM> that may have a different size according to the different power category and voltage ranges that the contactor shall provide. The switch base portion <NUM> includes electrical switching means <NUM>.

The upper arc extinguishing portion <NUM> may be structurally different according to the different voltage ranges, as shown in <FIG>, that must be treated and the corresponding arc chute type and energy capacity that shall be extinguished in total security.

An arc extinguishing portion <NUM> for a voltage value of <NUM> V may have the structure shown in <FIG>, <FIG> or <FIG> while an arc extinguishing portion for a higher voltage value up to <NUM> V may require a greater or thicker extinguishing portion and larger polar expansions.

According to the present invention, hardware means <NUM> are provided in the switch base portion <NUM> of the contactor <NUM> for attracting the electric arc when relatively low currents are switched by the contactor <NUM>. Such an electric arc is schematically shown in <FIG>, <FIG> and <FIG> with the number <NUM>.

These hardware means <NUM> include magnetic elements <NUM>, <NUM> positioned in the proximity of the moving contacts <NUM>, <NUM> of the contactor <NUM> to generate a magnetic field <NUM> sufficient to partially detour the electric arc <NUM> and to extinguish such an arc <NUM> generated in particular when low switched currents are involved.

Advantageously, those magnetic elements <NUM>, <NUM> are permanent magnets.

Moreover, said magnetic elements <NUM>, <NUM> are positioned at each lateral side of each moving contact <NUM>, <NUM>.

It should be noted that each of said magnetic elements <NUM>, <NUM> is structured as a disk supported laterally of a corresponding moving contact <NUM>, <NUM> in a fixed position when the moving contacts <NUM>, <NUM> are in the rest at the open position.

The shown embodiment of the contactor <NUM> includes at least four magnetic elements <NUM>, <NUM>, that is two for each moving contact <NUM>, <NUM>.

It is understood that said hardware means are active to detour the electric arc toward said top arc chute and they are mainly active when said low currents are flowing through the main contacts.

These magnetic elements <NUM>, <NUM> are supported in said casing <NUM> in an inclined position substantially perpendicular to a corresponding moving contact <NUM>, <NUM> and at predetermined distance of few millimeters from arc runners <NUM>, <NUM>.

The internal schematic structure of this switch base portion <NUM> including the electrical switching means <NUM> is shown in <FIG>.

The switch portion <NUM> may be considered conceptually separated in a low voltage portion <NUM> and a high voltage portion <NUM> located over the low voltage portion <NUM>. The low voltage portion <NUM> is provided for driving the switching of the internal moving contacts <NUM>, <NUM> of the upper high voltage portion <NUM>.

The contactor <NUM> of the present invention is a monostable element that is provided with normally open contacts according to the vast majority of customer requirements.

The internal moving contacts <NUM> and <NUM> of the upper high voltage portion <NUM> are put in abutment one against the other for allowing the passage or flow of the high DC current. Advantageously, said electrical contacts <NUM>, <NUM> are symmetrically moving towards and away from each other.

The contactor <NUM> includes a couple of reciprocally symmetrically moving contacts <NUM>, <NUM> driven towards and away from each other with respect to a central mutual contact position or abutting position.

Each moving contact <NUM> or <NUM> is positioned at the end of a corresponding elongated arm <NUM>, <NUM> of a toggle mechanism <NUM>, as shown in <FIG> and <FIG>. The arms <NUM>, <NUM> are manufactured by a conductive material, for instance a metal.

Over the contacts <NUM>, <NUM>, but still part of the switch base portion <NUM>, respective arc runners <NUM>, <NUM> are provided.

Those arc runners <NUM>, <NUM> are normally provided to help in dissipating the electric arc <NUM> formed during the opening phase of the moving contacts <NUM>, <NUM>. Depending on the application, arc running can be installed or not.

Each of the arc runner <NUM>, <NUM> is electrically connected to a respective dissipation or blow coil <NUM>, <NUM>. Each coil <NUM>, <NUM> is provided at the shoulder of each moving contact <NUM>, <NUM> of each arm <NUM>, <NUM>.

Each arc runner <NUM> or <NUM> is formed by a flat metal plate extended over the corresponding moving contact <NUM> or <NUM> when they are in the open or rest position. The upper flat metal plate is bent on both lateral sides with opposite flanges <NUM>, <NUM> that partially and laterally protect the corresponding moving contact <NUM> or <NUM>, as shown in <FIG>.

The lateral metal flanges <NUM>, <NUM> represent detouring elements that may attract the arc flow path as a function of the DC current direction, as shown by the arched curves <NUM> in <FIG>.

Advantageously, each magnetic element <NUM> or <NUM> is located outside a corresponding flange <NUM> or <NUM> laterally from the moving contact <NUM> or <NUM>.

Moreover, a polar expansion <NUM>, that is to say a metal plate, is provided on both sides of the moving contacts <NUM>, <NUM>. In <FIG> only one plate <NUM> is shown since only half a shell of the housing <NUM> is shown but it should be considered also the presence of a corresponding plate situated in a parallel position on the other side of the envelope with respect to the contacts <NUM>, <NUM>.

For completeness sake we will now disclose the other portions of the contactor <NUM> that are dedicated to the switching action.

The toggle mechanism <NUM> shown in <FIG> and <FIG> includes a couple of legs <NUM> and <NUM> that are joined at one end in a sliding hinge <NUM> that is moveable along a vertical slot <NUM> of the frame <NUM>. The legs <NUM> and <NUM> are made by an insulating material, for instance a thermosetting material.

The opposite ends of each of the legs <NUM>, <NUM> are hingedly linked to a corresponding end of the arms <NUM> and <NUM> supporting the moving contacts <NUM>, <NUM>, respectively. More specifically, each end of the arms <NUM>, <NUM>, opposite to the moving contacts <NUM>, <NUM>, is linked to a corresponding end of the legs <NUM>, <NUM>.

Each arm <NUM> or <NUM> is pivotally supported in the frame <NUM> by a corresponding pivot <NUM>, <NUM> in a position that corresponds substantially to one third of the whole longitudinal length of the arm.

The legs <NUM>, <NUM> and the arms <NUM>, <NUM>, together with the corresponding hinge joint <NUM> form said toggle mechanism <NUM> that allows driving the moving electric contacts <NUM> and <NUM> one toward the other and vice versa. The rods <NUM>, <NUM> as well as the arms <NUM>, <NUM> are formed by a couple of identical parallel components that are linked together more or less like a truss beam.

Between each of the pivots <NUM>, <NUM> and the corresponding fixed terminal power contact <NUM> or <NUM> there is a fork arm <NUM>, <NUM> made by a conductive material, such as a metal.

Those fork arms <NUM>, <NUM> are substantially linked to the fixed terminal power contacts <NUM> and <NUM> to provide electric continuity between the moving electric contacts <NUM>, <NUM> and the fixed terminal contacts <NUM>, <NUM>.

The toggle mechanism <NUM> is activated by the low voltage driving portion <NUM> that will be disclosed hereinafter.

The hinge joint <NUM> is provided with a central annular elastic element <NUM> that is contacted by an active end of the low voltage driving portion <NUM> and may be considered as a bumper between said active end and the whole toggle mechanism <NUM>. This hinge joint <NUM> is forced to slide along the vertical slot <NUM> by a sliding guide <NUM>, not visible in the drawings.

The low voltage driving portion <NUM> includes a coil <NUM> that is electrically supplied by a low voltage reference potential, not shown being of a conventional type and driven by a suitable switching actuator.

The coil <NUM> is active on a stem <NUM> that is extended horizontally and parallel to the base flange <NUM> of the contactor envelope <NUM> inside the switch base portion <NUM>. The stem <NUM> is moved against the contrast of an elastic element <NUM>, for instance an elongated spring to be compressed.

The free or distal end <NUM> of the stem <NUM> is linked to one end of a lever <NUM> which is pivotally mounted on a fulcrum <NUM> fixed or integral with the internal frame <NUM> of switch base portion <NUM> of the contactor <NUM>.

The lever <NUM> has a first arm linked to the free distal end <NUM> of the stem <NUM> and another or second arm free to move around the fulcrum <NUM> when the lever <NUM> is actuated by the coil <NUM> and the stem <NUM>.

The free end of this second arm is active on the hinge joint <NUM> of the toggle mechanism <NUM>.

It should be finally noted that an electric circuit <NUM> is provided for supplying the coil <NUM> related voltage values according to the different needs to drive the low voltage driving portion of the actuator. This circuit <NUM> is substantially a voltage level shifter suitable to receive a plurality of different voltage values. According to the present embodiment two types of electromagnets or coils <NUM> have been considered, that is to say: high and low voltage coils having a control card to control starting current and holding current. This electronic control of the main coil allows to combine a high closing power with a reduced power consumption during the holding phase.

In view of the previous description, the functioning of the contactor device <NUM> of the present invention is evident.

According to the solution idea at the basis of the present invention, in the contactor device <NUM> there is not a fixed contact but, on the contrary, a couple of movable contacts <NUM>, <NUM> that are driven towards and away from each other with respect to a mutual contact position.

According to set initial conditions, the electromagnet <NUM> of the low voltage driving portion <NUM> is biased to move the stem <NUM> that is joined to one end of the two arms lever <NUM> pivotally hinged on the fulcrum <NUM>.

The movement of the stem <NUM> moves the free end of the lever <NUM> that acts on the sliding hinge <NUM> of the toggle mechanism <NUM>. That sliding hinge <NUM> is free to move up and down or axially along a slot of the frame <NUM> so to push up or down and this movement forces the whole toggle mechanism <NUM> to provide a closure or an aperture of the moving contacts <NUM>, <NUM> accordingly.

The structure of the double symmetrically moving contacts <NUM>, <NUM> of the present invention allows obtaining a physical separation of the contacts of at least <NUM> that allows reducing the risk of electric arc and renders particularly reliable the switching of the contactor device of the invention with respect of the insulation characteristics.

Contacts <NUM> and <NUM> open with double speed and the toggle mechanism <NUM> guarantees also a higher distance between them.

The magnetic elements <NUM>, <NUM> positioned at both sides of the opposite flanges <NUM>, <NUM> of the arc runners <NUM>, <NUM> allow detouring the electric arc toward the top arc chute <NUM> mainly when low switching currents are involved.

The contactor according to the present invention may be used also for switching in high AC current applications.

In the previous lines the directional terms like: "forward", "rearward", "front", "rear", "up", "down", "above", "below", "upward", "downward", "top", "bottom", " side", "vertical", "horizontal", "perpendicular" and "transverse" as well as any other similar directional terms refer just to the device as shown in the drawings and do not relate to a possible use of the same device. Accordingly, these directional terms, as utilized to describe the contactor in its upright vertical position on a horizontal surface have just the meaning to identify a portion of the device with respect to another portion as shown in the figures.

The term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. This concept also applies to words of similar meaning, for example, the terms "have", "include" and their derivatives.

Claim 1:
Improved switching or contactor device (<NUM>) with high arc extinguishing capabilities, in particular for industrial and railways applications wherein a high current must be switched on and off, said switching or contactor device (<NUM>) comprising in a casing (<NUM>):
- a switch base portion (<NUM>) including electrical switching means (<NUM>) of a low voltage driving portion (<NUM>) active on moving contacts (<NUM>, <NUM>);
- a high voltage portion (<NUM>) including said moving contacts (<NUM>, <NUM>) driven towards and away from each other with respect to a mutual contact position, said moving contacts (<NUM>, <NUM>) being mounted at respective contact ends of a toggle mechanism (<NUM>) which is movable by a low voltage driving portion (<NUM>), and
- a top arc chute extinguishing portion (<NUM>) covering said high voltage portion (<NUM>),
characterized by comprising:
hardware means (<NUM>) provided in the proximity of said moving contacts (<NUM>, <NUM>) to influence an electric arc (<NUM>) occurring when currents are switched on and off by the moving contacts (<NUM>, <NUM>) moving towards and away from each other, wherein
respective arc runners (<NUM>, <NUM>) are provided over each corresponding moving contact (<NUM>, <NUM>) in their open or rest position and said hardware means (<NUM>) are magnetic elements (<NUM>, <NUM>) positioned at both sides of each arc runner (<NUM>, <NUM>), and
the magnetic elements (<NUM>, <NUM>) are positioned at each lateral side of each moving contact (<NUM>, <NUM>).