Patent Description:
In photovoltaic systems, the currents produced by the individual photovoltaic cells are combined in order to reach the current and the total power needed by the utilization system. In a photovoltaic system, the photovoltaic cells, the photovoltaic modules that comprise them and the strings of these photovoltaic modules can be protected, or disconnected, using DC disconnectors, which are rotary switches that can be actuated by hand.

Conventional disconnectors are described in European patent <CIT> in the name of the same applicant and are formed by a plurality of modular contact boxes which are substantially identical and stacked on each other. Each contact box, also called a module or layer, generally comprises a rotary contact and a pair of fixed contacts. The grouped rotation of the rotary contacts makes it possible, in an extremely short time, to cut off or to allow the flow of current between the two fixed contacts in each contact box.

The rotation is imposed manually through a snap-action switch box, which is placed at the top of the stack of contact boxes and comprises a handle that can be operated by the user. The rotation imparted by the handle is progressively transmitted from one rotary contact directly to the one immediately underneath by snap action, by virtue of a shape coupling between the rotary contacts. This shape coupling is obtained by having, on one face of the rotary contact, a contoured central pin and, on the other face, a central seat shaped complementarily to the pin and adapted to receive the contoured pin of the rotary contact of the contiguous layer in order to transmit the rotation.

One problem with these conventional disconnectors is that it is not possible to ensure the simultaneity of the opening and closing of the contacts, because the mechanical plays between one rotary contact and the one contiguous to it are summed together, and the rotary contacts of the deeper layers respond less quickly to the rotation imparted by the rotary contact nearest to the snap-action switch box. These response delays do not allow to to have a DC disconnector with a number of layers or circuits higher than a certain limit, because it would not be capable of passing the safety tests specified by some current regulations such as for example the IEC <NUM>-<NUM> standard (test sequence III: "Short-circuit performance capability").

For this reason, with the conventional structure described above in which the rotary contacts transmit the rotation directly from one to the next through a mutual shape coupling, it has been found that it is not possible to pass the above mentioned tests with a DC disconnector with more than <NUM> layers.

In addition, in DC disconnectors for high power levels, in which some positive contacts are arranged in series in each circuit of the disconnector, it is not possible to have more than three circuits in the same disconnector.

Another drawback is that, with the snap-action switch box in conventional disconnectors, such as for example those described in patent applications nos. <CIT> or <CIT>, a metal lamina locking spring is used. If it is desired to reduce the metal components of this conventional structure, by replacing the lamina with an elastic element made of plastic, the resulting structure could pass the mechanical tests according to the IEC <NUM>-<NUM> standard (test sequence II: "Operational performance capability") in an unencumbered area, but those tests might not be passed in a climate chamber at high temperatures and with high levels of humidity, owing to the wear of the plastic components in contact with each other. This is a significant drawback, since the preferred use of the DC disconnector is in the photovoltaic sector and therefore it occurs in environments that can have high temperatures and high levels of humidity.

Document <CIT> discloses a device according to the preamble of claim <NUM>.

The aim of the present invention is to provide a disconnector that is capable of improving the known art in one or more of the above mentioned aspects.

Within this aim, an object of the invention is to provide a DC disconnector that is adapted to pass the safety test even with a large number of modules or layers, for example with <NUM> layers.

Another object of the invention is improve the simultaneity of rotation of the rotary contacts of the disconnector, by reducing the rotation delays that characterize the rotary contacts of the layers that are further from the snap-action switch box and which, in the known art, increase instead when the number of modules of the disconnector increases.

Another object of the invention is to provide a disconnector wherein the snap-action switch box has a reduced number of metallic elements compared to conventional snap-action switch boxes and is adapted to operate reliably even at high temperatures and at high levels of humidity.

Another object of the invention is to provide a DC disconnector that is capable of passing the IEC <NUM>-<NUM> tests, in particular the "Test sequence III", even with more than <NUM> layers or modules and even in those cases where, in order to have a higher voltage for the same amperage, the positive poles of some adjacent modules are connected to each other in series.

Another object of the invention is to provide a disconnector so as to simplify its maintenance or updating.

Furthermore, the present invention sets out to overcome the drawbacks of the background art in a manner that is alternative to any existing solutions.

Another object of the invention is to provide a disconnector that is highly reliable, easy to implement and of low cost.

This aim and these and other objects which will become better apparent hereinafter are achieved by a disconnector according to claim <NUM>, optionally provided with one or more of the characteristics of the dependent claims.

The aim and the objects of the invention are likewise achieved by a disconnector according to claim <NUM>, optionally provided with one or more of the characteristics of the dependent claims.

Further characteristics and advantages of the invention will become better apparent from the description of preferred, but not exclusive, embodiments of the disconnector according to the invention, which are illustrated by way of non-limiting example in the accompanying drawings wherein:.

With reference to the figures, a DC disconnector according to an embodiment of the invention, particularly for photovoltaic applications, is generally designated by the reference numeral <NUM> and comprises a stack <NUM> of modular contact boxes which is surmounted by a snap-action switch box <NUM>. The stack <NUM> can have a substantially prismatic shape, for example substantially parallelepiped.

In the example shown, the modular contact boxes stacked one on top of the other are twelve in number and are indicated with 2a, 2b, 2c, 2d, 2e, 2f, <NUM>, <NUM>, 2i, 2j, <NUM>, <NUM>. The number of modular contact boxes of the disconnector <NUM> according to the invention can, however, be any number, for example a number comprised between <NUM> and <NUM> modular contact boxes, but more preferably comprising a high number of modular contact boxes like those illustrated, for example at least <NUM> or, even more preferably, at least <NUM>, <NUM> or <NUM> modular contact boxes.

The modules 2a-<NUM> are preferably identical to each other, except for optionally the last module <NUM> of the stack <NUM>, which is the furthest from the snap-action switch box <NUM> and can be externally contoured differently, for example with fixing lugs and/or other elements for mounting on external support structures.

The disconnector <NUM> can, furthermore, comprise means for fastening the modular contact boxes 2a-<NUM>, each one of which comprises a tie rod <NUM>, made of plastic, or of suitably insulated metal, and passes through each modular contact box 2a-<NUM> of the stack <NUM>. The tie rod <NUM> comprises, at a first end, two grip wings <NUM> that engage with a seat <NUM> provided in the snap-action switch box <NUM> of the disconnector <NUM>, and, at a second end, a threaded hole for the insertion of a securing screw <NUM> that passes through, for example, the above mentioned lugs of the last contact box <NUM>, or which in any case passes through the base portion of the disconnector <NUM>.

Considering, for the sake of simplicity of explanation, that the modules 2a-<NUM> are identical to each other, each one of them comprises an accommodation body <NUM> (<FIG>), which can be polygonal in plan view, for example quadrangular in plan view, as in the case shown, wherein the outer plan is substantially rectangular.

Each accommodation body <NUM>, made of electrically insulating material, for example of molded polymeric material, is axially contoured along at least two peripheral edges <NUM> and <NUM> of its upper and lower faces, so that such edges <NUM> and <NUM> have a mutually complementary shape and enable a coupling with the accommodation body <NUM> of a contiguous module arranged immediately above or immediately below in the stack <NUM>, while preventing a mutual rotation and a relative radial translation. In the embodiment illustrated, the edges <NUM> and <NUM> have a substantially wave-like shape.

In the preferred embodiment of the invention, the coupling between the edges of two consecutive accommodation bodies <NUM> is axially removable, i.e. the two accommodation bodies are not fixed to each other in the axial direction by the coupling of the edges alone.

The accommodation body <NUM> defines a through central seat <NUM>, for a rotary contact <NUM>, and two peripheral seats <NUM>, each one of which accommodates a connection portion <NUM> of a fixed contact <NUM>, which can be accessed from outside the modular contact box 2a-<NUM>. The rotary contact <NUM> can rotate about a central axis 40a of the central seat <NUM> relative to the accommodation body <NUM>, in order to engage, only in predefined angular positions, with the fixed contacts <NUM>, which are arranged with the connection portion <NUM> thereof in the peripheral seats <NUM>.

The accommodation body <NUM>, together with the rotary contact <NUM> and the fixed contacts <NUM>, defines the (modular) contact box 2a, 2b,. , herein also referred to as a "module" or "layer".

The two peripheral seats <NUM> of a same accommodation body <NUM> are arranged on a same side with respect to an ideal central plane A that passes through the axis 40a, which is preferably also the central plane of the stack <NUM> and of the disconnector <NUM>. Furthermore, in the stack <NUM> of the disconnector <NUM> the two peripheral seats <NUM> of an accommodation body <NUM> and the two peripheral seats <NUM> of each contiguous (i.e. immediately above or below) accommodation body <NUM> are arranged on mutually opposite sides with respect to the ideal central plane A.

In the illustrated case of an accommodation body <NUM> that is substantially rectangular in plan, the central seat <NUM> passes through the two opposite faces of the accommodation body <NUM> and the ideal central plane A mentioned above is parallel to the two opposite sides <NUM>, <NUM> of the accommodation body <NUM>.

In the stack <NUM> of the disconnector <NUM>, the peripheral seats <NUM> that accommodate the fixed contacts <NUM> are arranged, for each modular contact box 2a-<NUM>, alternately proximate to the side <NUM> and to the opposite side <NUM> of the disconnector <NUM> respectively.

Each fixed contact <NUM> comprises a connection portion <NUM>, a contact portion <NUM>, and a connecting portion <NUM> that extends between the connection portion <NUM> and the contact portion <NUM>.

The contact portion <NUM> of the fixed contact <NUM> is adapted to establish an electrical contact with the rotary contact <NUM>. In particular, the contact portions <NUM> of the fixed contacts <NUM> can be advantageously arranged at the ideal central plane A.

The connection portion <NUM> can be accessed from outside the modular contact box 2a-<NUM>, and from outside the disconnector <NUM>. This connection portion <NUM> in fact can comprise a screw tightening system <NUM>, for tightening and connecting the connection portion to an external electrical conductor (or cable).

In an alternative embodiment, not shown, in each modular contact box it is possible to use, instead of the illustrated screw tightening system <NUM>, a cage clamp, per se conventional, particularly if the external electric conductors to be connected are high-amperage, for example over 100A.

In the first example of electrical connection (<FIG>, <FIG>, <FIG>) the electrical conductors outside each circuit are electrical cables indicated with 57a, 57b, 57c, 57d, 57e and are such as to provide, on one face of the disconnector <NUM>, a pair of positive poles and one negative pole for each circuit (for a total of four circuits in the case of twelve contact boxes, in <FIG>).

Advantageously, the electrical cable 57d that directly connects (shortcircuits) two connecting portions <NUM> of two contiguous modules to each other is also completely outside the disconnector <NUM>, differently from the conventional solutions above mentioned. This externally-directed connection of the disconnector facilitates the setup of the desired circuits with a same pre-assembled disconnector <NUM> without cables and allows the substitution of any damaged electrical cables 57d when the disconnector <NUM> is already installed.

In an alternative circuit implementation, also illustrated by way of example in <FIG> and <FIG>, the external electrical cables 157a-157e are arranged so as to connect directly in series three contiguous contact boxes (2b-2c-2d; 2f-<NUM>-<NUM>; 2j-<NUM>-<NUM>) in order to provide one positive and one negative pole, alternating, on both the faces of the disconnector from which the connecting portions <NUM> are accessible.

The rotary contact <NUM> comprises a metal conducting portion <NUM> which defines two electrical end portions <NUM>, preferably in the form of terminals or blades and adapted to come into direct electrical contact with the contact portions <NUM> of the fixed contacts <NUM> of the respective module, according to their angular position about the axis 40a. The metal conducting portion <NUM> can be interposed between an insulating rotary support <NUM>, which is accommodated in the central seat <NUM>, and a cover <NUM>, which is also preferably made of insulating material. The end portions <NUM> of the rotary contact <NUM> protrude partially from this <NUM> rotary support and from this cover <NUM>.

Each rotary contact <NUM> comprises a central through hole <NUM>, which is coaxial with the rotation axis 40a common to all the modules 2a-<NUM> when the rotary contact <NUM> is mounted in the central seat <NUM> of the respective contact box of the stack <NUM>.

The through hole <NUM> is contoured so as to have a shape complementary to that of a single actuation rod <NUM> that passes through all of the stack <NUM> coaxially with the rotation axis 40a of the rotary contacts <NUM>, so as to have a shape coupling between the rod <NUM> and the holes <NUM> that is substantially free from play. In the preferred embodiments of the invention, the shape of the central hole <NUM> and the shape of the actuation rod <NUM> is substantially prismatic, for example parallelepiped.

The actuation rod <NUM> is provided in a single piece, made of metallic or polymeric material. In the preferred embodiments, the single-piece actuation rod <NUM> is constituted by composite material, for example a polyamide (possibly semi-aromatic or PPA) loaded with glass fibers, for example for <NUM>% by weight. It is possible however to provide, as an alternative, an actuation rod <NUM> made entirely of metal, optionally covered in electrically insulating material.

In alternative embodiments, not shown, the actuation rod <NUM> can be constituted by a plurality of rod-like modules which are fixed rigidly and coaxially to each other so as to form a single actuation rod <NUM>. Each one of these rod-like modules is provided in a single piece (for example made of the same materials mentioned above with reference to the single-piece actuation rod) and is rotationally fixed to at least two respective rotary contacts <NUM> of the two adjacent modular contact boxes that the rod-like module passes through coaxially with the central axis 40a. The fixing of the single rod-like module to the two or more rotary contacts <NUM> occurs preferably in a manner similar to the example shown above, i.e. with a shape coupling between the rod-like module and the holes <NUM> of the two or more adjacent rotary contacts. In this manner, it is possible to provide disconnectors of different dimensions, by composing the rod-like modules in order to obtain a single actuation rod <NUM> of suitable length for the desired disconnector.

The actuation rod <NUM> is coaxial with a drive shaft <NUM> of the snap-action switch box <NUM> and is adapted to rigidly transmit the rotation transmitted by the snap-action switch box <NUM> to all the rotary contacts <NUM>. By virtue of the use of a single actuation rod <NUM> shared by all the rotary contacts <NUM>, which are rotationally secured thereto preferably through a shape coupling, the speed of response of the rotary contacts <NUM> to the rotation imparted by snap action through the switch box <NUM> is considerably improved, even in presence of a large number of modules in the stack <NUM>. For example, in the embodiment illustrated with twelve contact boxes 2a-<NUM>, it has been found that the rotation delays of the rotary contacts to the ON position are of the order of one-tenth of a degree, while in a structure like that of the prior art patent <CIT>, which does not have a common actuation rod, the delays of the contact boxes furthest from the snap-action switch box can be of the order of <NUM>° and more.

<FIG> shows one of the modular contact boxes 2a-<NUM> which are identical to each other but are mounted each rotated <NUM>° with respect to the next one in the stack <NUM>. This contact box has the electrical contacts in the "OFF" configuration, in which the end portions <NUM> of the rotary contact <NUM> are not in contact with the contact portions <NUM> of the fixed contacts <NUM> (but are at an angular distance of <NUM>° with respect to the axis 40a), thus preventing the flow of electric current between the two fixed contacts <NUM>.

According to the invention, the snap-action switch box <NUM> of the disconnector <NUM> comprises a spring-loaded switching structure in which the elements that slide against each other, by means of which the spring is loaded/released, are made of plastic or polymeric material.

The snap-action switch box <NUM> comprises, in particular, a covering element <NUM> which is passed through axially by the drive shaft <NUM>. The drive shaft <NUM> is rigidly connected to a spindle loading support <NUM> of a spring <NUM>, which is a torsion spring, for example of the helical type with arms that protrude transversely with respect to the turns of the spring.

The spindle loading support <NUM>, which is contained vertically by the covering element <NUM> so as to be able to rotate about the axis 40a, can be made of polymeric material, preferably composite or reinforced with glass fibers or balls. Advantageous polymeric materials can be polyamide (for example, PA66 or polyamide <NUM>) or the polyoxymethylene.

The spindle loading support <NUM> is preferably shaped like a circular disk with axial protrusions, is perforated centrally in order to allow an integral rotational coupling with the drive shaft <NUM> and is provided, on the face opposite to the face from which the drive shaft <NUM> protrudes, with a first eccentric contrasting wall <NUM>, with a spindle body <NUM> and with one or more release teeth <NUM>.

Preferably the release teeth <NUM> are two in number and are arranged in diametrically opposite positions with respect to the central axis of the support <NUM>, while the first eccentric contrasting wall <NUM> is arranged at an angular distance of substantially <NUM>°, measured with respect to the center of the circular disk, from each release tooth <NUM>.

The first eccentric contrasting wall <NUM> can have a reinforcement ramp 61a and an abutment step 61b.

The spindle body <NUM>, which can be substantially cylindrical as in the example shown, is coaxial with the rotation axis 40a and is adapted to freely support the spring <NUM> so as to allow the torsion thereof.

In particular, the spring <NUM> is freely fitted over the spindle body <NUM> and has a first end 64a directed transversely to the direction toward which the wall for contrasting <NUM> extends, for example, directed radially with respect to the spring <NUM>.

The first end 64a of the spring <NUM> faces laterally toward the eccentric contrasting wall <NUM>, in particular it faces toward the base of the wall <NUM> and toward the opposite side with respect to the ramp 61a, so as to abut against the wall <NUM> during the rotation of the spindle loading body <NUM> in a direction of loading the spring <NUM>, for example clockwise in the case of the disconnector <NUM>.

The second end 64b of the spring <NUM> is angularly and axially spaced apart from the first end 64a and faces, in the resting condition of the spring, onto the abutment step 61b located at the summit of the ramp 61a. In its resting condition, the spring <NUM> can optionally be preloaded.

The second end 64b of the torsion spring <NUM> further abuts against a second eccentric contrasting wall <NUM> which protrudes from a driven indexing element <NUM>.

The driven indexing element <NUM> is rotatably associated with the spindle loading support <NUM> so as to be able to rotate with respect to the latter about the central axis 40a, passing centrally through the driven element <NUM>.

The driven element <NUM> has a circular base <NUM>, which is adapted to rotate in a guided manner about the central axis 40a within a corresponding annular seat <NUM> of the base <NUM> of the snap-action switch box <NUM>.

The second eccentric contrasting wall <NUM> protrudes from the disk-like base <NUM> in an eccentric position and toward the spindle loading support <NUM> so that, in the resting condition of the spring <NUM>, the contrasting walls <NUM> and <NUM> are facing toward each other in a radial direction. In the embodiment illustrated, the radial distance of the second contrasting wall <NUM> with respect to the rotation axis 40a is greater than that of the first contrasting wall <NUM>, but it is also possible to have an opposite positioning in other embodiments.

The second eccentric contrasting wall can also comprise a reinforcement ramp 71a and a step 71b, but in the assembled structure the ramp 71a extends away from the step 71b in a direction opposite to that in which the ramp 61a of the first wall <NUM> extends away from the respective step 61b.

In the resting condition, the protruding ends 64a-64b of the torsion spring <NUM> face toward the sides of both the contrasting walls <NUM> and <NUM>, so that the spring <NUM> fitted over the spindle body <NUM> is substantially across both the contrasting walls <NUM> and <NUM>.

In a central position, the disk-like base <NUM> comprises a contoured hole <NUM> shaped complementarily to the outer shape of the actuation rod <NUM> of the rotary contacts <NUM>, so as to enable a shape coupling that makes the driven indexing element <NUM> and the rod <NUM> integral in rotation. The rod <NUM> can also be fixed centrally to the driven element <NUM> in a manner different from shape coupling.

The driven indexing element <NUM> further comprises a plurality of indexing arms, in particular two pairs of indexing arms 73a-73b and 74a-74b.

The pairs of indexing arms 73a-73b and 74a-74b of the driven element <NUM> are elastically flexible in the axial direction, i.e. substantially parallel to the axis 40a, and protrude in a cantilever fashion from respective posts 73c and 74c which protrude from the disk-like base <NUM>.

Preferably, the pairs of indexing arms 73a-73b and 74a-74b have substantially the shape of an arc of circumference which, starting from the respective post 73c, 74c, extend progressively away from the disk-like base <NUM> without remaining parallel to the disk-like base <NUM>, i.e. without having surfaces parallel to this base <NUM>.

For example, each indexing arm 73a, 73b, 74a, 74b extends away from the respective post 73c, 74c following a segment of a respective helix coaxial with the axis 40a of the driven element <NUM>. In particular, the diametrically opposite arms 73a and 74b can follow a segment of a respective dextrorotatory helix and the diametrically opposite arms 73b and 74a can follow a segment of a respective levorotatory helix.

The indexing arms 73a, 73b, 74a, 74b form preferably two C-shapes, sloping (for example between <NUM>° and <NUM>°) with respect to the disk-like base <NUM>, as can be seen in particular from <FIG>, and are substantially mirrorsymmetrical with respect to a diametrical plane that passes through the second contrasting wall <NUM> and the rotation axis 40a.

The posts 73c and 74c are arranged in diametrically opposing peripheral positions of the disk-like base <NUM> and protrude in the same direction as the second contrasting wall <NUM>, from which they are spaced apart by an angle of substantially <NUM>°. With this arrangement, the second contrasting wall <NUM> can be substantially interposed between the ends of two indexing arms 73a-74a that face toward each other.

Each C-shaped pair of arms 73a-73b and 74a-74b is integral with the respective post 73c, 74c at its center.

The spindle loading element <NUM> is advantageously mounted on the indexing element <NUM> so that the two release teeth <NUM> are superimposed, in the resting condition of the spring <NUM>, on the posts 73c and 74c, respectively.

Each indexing arm 73a, 73b, 74a, 74b comprises, at its free end, at least one detent pawl <NUM>, <NUM>, <NUM>, <NUM>, obtained by way of an increase in thickness, preferably progressive, in the axial direction of the respective arm 73a, 73b, 74a, 74b, away from the disk-like base <NUM>, i.e. toward the spindle loading element <NUM>.

Each detent pawl <NUM>, <NUM>, <NUM>, <NUM> comprises an upper sliding surface adapted to block the release teeth <NUM> during the rotation of the spindle loading support <NUM> with respect to the driven element <NUM>, causing the lowering of the respective arm 73a, 73b, 74a, 74b toward the disk-like base <NUM>, as explained below.

According to an advantageous aspect of the invention, the driven indexing element <NUM> is made of polymeric material, preferably different from the material with which the spindle loading support <NUM> is made. The polymeric material of the driven element <NUM> is advantageously a composite or reinforced material, for example with glass fibers or balls.

The polymeric material can be, for example, a polyamide, like PA6 (polyamide <NUM>). The PA6 used to make the driven element <NUM> can be strengthened with glass fibers or glass balls, preferably between <NUM>% and <NUM>% by weight, for example with <NUM>%, <NUM>% or <NUM>% by weight of glass fibers/balls.

The driven indexing element <NUM> is contained in the axial direction by a positioning element <NUM>, which is fixed to the base <NUM> of the snap-action switch box <NUM> so as to allow the partial rotation of the driven element <NUM> about the axis 40a.

The positioning element <NUM> can be made of polymeric material which can optionally be reinforced, such as, for example, polyoxymethylene, and preferably chosen to be different from the polymeric material with which the driven element <NUM> is made.

The positioning element <NUM> comprises a circular opening provided with an indexing ring <NUM> which is coaxial with the axis 40a, which has an internal radius preferably greater than that of the circular disk of the loading support <NUM> and smaller than the maximum radial distance of the detent pawls <NUM>, <NUM>, <NUM>, <NUM> with respect to the axis 40a.

The indexing ring <NUM> has a diameter sufficient to axially contain the driven element <NUM> within the positioning element <NUM> and to allow the interaction of the detent pawls <NUM>, <NUM>, <NUM>, <NUM> of the driven element <NUM> with the release teeth <NUM> of the loading support <NUM>.

With the rotation imposed on the spindle loading support <NUM>, the release teeth <NUM> can thus rotate about the axis 40a within the circular opening defined by the indexing ring <NUM>, through which the release teeth <NUM> can block the detent pawls <NUM>, <NUM>, <NUM>, <NUM> of the driven element <NUM>.

The indexing ring <NUM> comprises indexing teeth <NUM> arranged in diametrically opposite positions, so as to define only four stop points of the rotation of the driven element <NUM> about the axis 40a in at least one direction of rotation.

Each indexing tooth <NUM> is substantially a ratchet tooth, so as to present a ramp and abutment surface on the flank of the indexing tooth <NUM>, the flank preferably extending on a plane of arrangement of the axis 40a.

The indexing teeth <NUM> are preferably four in number and are arranged along the ring <NUM> substantially on opposite sides with respect to the central plane A of the modules 2a-<NUM> of the disconnector <NUM>, so that one pair of indexing teeth <NUM> is in a diametrically opposite position from the other pair of indexing teeth, and so that the flanks of the indexing teeth <NUM> of each one of such pairs face each other mirror-symmetrically with respect to the above mentioned central plane A.

Each arc of the indexing ring <NUM> comprised between the two mutually-facing flanks of a pair of indexing teeth advantageously has an extension such that it contains a detent pawl <NUM>, <NUM>, <NUM>, <NUM> of the driven element <NUM>, with the indexing arms 73a-74a, 73b-74b in the resting condition or preloaded condition. With the arms in these conditions, a rotation of the driven element <NUM> about the axis 40a is prevented by the side of the respective indexing tooth <NUM> on which two diametricallyopposite detent pawls <NUM>-<NUM>, <NUM>-<NUM> abut.

The abutment flank of each indexing tooth <NUM> can be abutted by the front part of two respective detent pawls (<NUM>-<NUM> or <NUM>-<NUM>) which are located at a diametrically opposite position on the driven element <NUM> and which have, therefore, the normal of the plane of their front part with a direction substantially matching a same direction of rotation of the driven element <NUM> (anticlockwise for the pawls <NUM> and <NUM>, clockwise for the pawls <NUM> and <NUM>).

Preferably, the thickness of the detent pawls <NUM>, <NUM>, <NUM>, <NUM> in a radial direction is such as to enable, with the relative rotation between the driven element <NUM>, the loading support <NUM> and the positioning element <NUM>, the interaction of the detent pawls <NUM>, <NUM>, <NUM>, <NUM> both with the release teeth <NUM> (during the release of the click) and with the indexing teeth <NUM> on the indexing ring <NUM> (during the loading of the spring <NUM> and the arrest of the rotation subsequent to the click). In particular, two different portions 731a-731b, 732a-732b, 741a-741b, 742a-742b of the detent pawls <NUM>, <NUM>, <NUM>, <NUM> are engaged, respectively: a radially innermost pawl 731a, 732a, 741a, 742a can engage the release teeth <NUM>, and a radially outermost pawl 731b, 732b, 741b, 742b can engage the indexing teeth <NUM>.

Operation of the disconnector according to the invention is clear and evident from the foregoing description.

The snap-action switch box <NUM> is configured so that, in a stable or resting condition, all the rotary contacts <NUM> of the disconnector <NUM> are in the ON angular position or in the OFF angular position (as in <FIG>).

In both these inactive conditions, the mutually-facing detent pawls of the driven element (<NUM>-<NUM> and <NUM>-<NUM>) are arranged across a respective indexing tooth <NUM>, while the two release teeth <NUM> of the spindle loading support <NUM> are kept substantially above the posts 73c and 74c. The indexing arms 73a-74a-73b-74b are all in a resting condition or, in an alternative embodiment, in a preloaded condition (in which case a friction is always maintained between the indexing ring <NUM> and the detent pawls <NUM>, <NUM>, <NUM>, <NUM>).

By imparting a manual rotation on the drive shaft <NUM>, for example through a handgrip fixed thereto, the spindle loading support <NUM> is rotated integrally, about the axis 40a, and remains substantially idle for a certain portion with respect to the driven element <NUM> and therefore with respect to the actuation rod <NUM>.

With the above mentioned rotation of the spindle support <NUM>, the first eccentric contrasting wall <NUM> loads the torsion spring <NUM> through, for example, the first end 64a. In the meantime, the other end 64b of the spring <NUM> is in abutment on the second eccentric contrasting wall <NUM> without substantially turning the driven indexing element <NUM>, which is stopped by the ratchet system formed by the detent pawls <NUM>-<NUM> and by the respective (flanks of the) indexing teeth <NUM> against which the spring <NUM> keeps them in abutment.

When, continuing the manual rotation of the support <NUM>, the release teeth <NUM> intercept the detent pawls <NUM>-<NUM>, these detent pawls are lowered toward the disk-like base <NUM> until they no longer encounter the resistance of the flanks of the respective indexing teeth <NUM> and thus freeing the rotation of the driven element <NUM>. The elastic force of the loaded spring <NUM> that acts on the second eccentric contrasting wall <NUM> therefore makes the driven element <NUM> turn very rapidly (for example in <NUM>-<NUM> milliseconds) by <NUM>°, bringing the spring <NUM> back to the initial condition (resting or preloaded) and bringing the detent pawls <NUM>-<NUM> across the next indexing tooth <NUM> of the ring <NUM>. With this snap-action rotation, the driven element <NUM> entrains rigidly with it, by a same angle of approximately <NUM>°, all the rotary contacts <NUM> of the disconnector <NUM>, in particular by virtue of the single rod <NUM> that rigidly connects them.

In this manner, the rotary contacts <NUM> simultaneously click from the ON position to the OFF position (or conversely, depending on the initial position), without there being significant delays or discrepancies between the rotary contacts, even if there is a high number of modules in the disconnector.

Furthermore, by virtue of the plastic materials used to make the elements of the switch box and by virtue of the inclination of the indexing arms of the driven element, it has been found that the switch box is capable of operating reliably even in hot and humid environments.

Among other things, the choice to use different plastic materials for the parts that operate in friction with each other makes it possible to reduce their wear and maintain electrical isolation.

In practice it has been found that the invention fully achieves the intended aim and objects.

Claim 1:
A disconnector (<NUM>), particularly for photovoltaic applications, comprising a stack (<NUM>) of modular contact boxes (2a-<NUM>) which is surmounted by a snap-action switch box (<NUM>), each modular contact box (2a-<NUM>) comprising an accommodation body (<NUM>), each accommodation body (<NUM>) having a central seat (<NUM>) which accommodates a rotary contact (<NUM>) and two peripheral seats (<NUM>), each one of which accommodates a connection portion (<NUM>) of a respective fixed contact (<NUM>) which can be accessed from the outside of said modular contact box (2a-<NUM>), said rotary contact (<NUM>) being rotatable with respect to said accommodation body (<NUM>) about a central axis (40a) of said central seat (<NUM>) in order to engage/disengage with respect to the fixed contacts (<NUM>), each rotary contact (<NUM>) comprising a central hole (<NUM>),
characterized in that:
- the snap-action switch box (<NUM>) comprises a driven indexing element (<NUM>) which is rotatably associated with a spindle loading support (<NUM>) so as to be able to rotate with respect to said spindle loading support (<NUM>) about the central axis (40a), said snap-action switch box (<NUM>) further comprising a spring (<NUM>) connected between said spindle loading support (<NUM>) and said driven indexing element (<NUM>) in order to load them elastically with respect to each other following a mutual rotation about the central axis (40a), the spring (<NUM>) being a torsion spring with arms that protrude transversely with respect to the turns of the spring (<NUM>), the arms defining two ends (64a, 64b) of the spring (<NUM>) which are angularly and axially spaced apart from each other; and
- the disconnector (<NUM>) comprises a single actuation rod (<NUM>) which passes through all the modular contact boxes (2a-<NUM>) coaxially to the central axis (40a) and is fixed in rotation to all the rotary contacts (<NUM>).