ITVI20080307A1 - BISTABLE SWITCHING DEVICE WITH ROPE - Google Patents

Description

DESCRIPTION

Field of application

The present invention is generally applicable to the technical sector of electrical safety elements and particularly relates to a cable switching device of the type with a bistable function applicable to safety or emergency electric circuits.

State of the art

As is known, the devices used for bistable switching of electrical contacts by means of cable or tie rod operation comprise a manually operated switch associated with a relay of the bistable type.

Typically, the switching of an electrical load for the opening / closing of a circuit is performed by controlling the switch through suitable mechanisms, while the relay has the function of keeping the switch in an intermediate position of electrically switched contacts to allow intervention or exclusion of the circuit.

Other devices, one of which is illustrated in the GB2330195 patent, have in place of the relay an actuator that can be operated mechanically to carry out the bistable function.

These devices are used, for example, to control the switching on and off of safety lights inside an elevator shaft, during inspection and / or maintenance operations.

A recognized drawback of these known solutions is represented by the fact that the presence of two separate devices, such as the switch and the relay or homologous device, requires a rather onerous and complex installation and management.

These devices are made up of a relatively large number of components, requiring difficult assembly, frequent maintenance and high production costs.

To overcome these drawbacks, some switches with bistable operation have been created, described for example in GB876969 and GB21 76940, in which the switching of the electrical load and the maintenance of the state of the electrical contacts are achieved by means of a switching unit consisting of a mechanism of single control, for example a system of levers or cylindrical bodies in relative rotation to each other.

However, these solutions require the provision of switches having a single box-like body to contain both the switch unit and the bistable function switching unit.

Consequently, it is necessary to specifically design all the components of the device, thus realizing proprietary switches.

Therefore, any replacement of one or more of the components would require the replacement of the entire device, with an evident increase in overall costs.

Presentation of the invention

The purpose of the present invention is to overcome the drawbacks encountered above, realizing a bistable cable switching device which has characteristics of high efficiency and relative cheapness.

A particular purpose is to create a bistable cable switching device that allows a simple replacement of one or more of its components, thus not requiring the replacement of the entire switch in the event that only some parts need to be replaced.

A further object is to provide a switching device which is simple and quick to install and which does not require wiring or other complex operations preliminary to its application.

Still another object is to provide a switching device which is formed by a relatively small number of components to ensure simplicity and cost-effectiveness of manufacture.

These purposes, as well as others which will appear more clearly in the following, are achieved by a bistable cable switching device, in accordance with claim 1, comprising a box-like body housing inside it at least one switch connectable to an electrical circuit for the Selective opening / closing thereof, a switching unit operatively associated with said at least one switch to promote the switching between a first circuit closing condition and a second circuit opening condition.

The switching unit comprises an actuator which can be associated with an actuation cable and means for guiding said actuator between a first and a second stable operating position corresponding respectively to said first and said second condition of said circuit.

According to a peculiar characteristic of the invention, the switching unit is removably connected to the box-like body, locking means being provided which are capable of keeping said switching unit constantly assembled in said first or said second stable position to allow its integral removal from said body. box-like.

In this way it will be possible to remove the entire switching unit from the first box-like body that houses the switch, keeping it in an assembled condition and ready for use.

Thanks to this feature, the switching unit can be applied to any body housing a switch making the entire device bi-stable, even if the switch body has not been specifically designed for the specific switching unit.

In this text, the expression â € œbistable functionâ € for the switching unit clearly refers to the possibility for the same unit to pass between a first operating condition and a second operating condition, remaining blocked in the acquired state up to a new actuation performed by a user. Advantageous embodiments of the invention are carried out in accordance with the dependent claims.

Brief description of the drawings

Further characteristics and advantages of the invention will become more evident in the light of the detailed description of a preferred but not exclusive embodiment of a cable switching device according to the invention, illustrated by way of non-limiting example with the aid of the accompanying drawing tables. in which:

FIG. 1 is a perspective view of a switching device according to the invention in a particular application;

FIG. 2 is a sectional front view of the device of Fig. 1; FIG. 3 is a front view of a switching unit and of three different box-like bodies 2 which can be selectively combined with the first to make a device according to the invention;

FIG. 4 is an exploded perspective view of the device of Fig .1; FIG. 5 is an exploded perspective view of a detail of the device of Fig. 1;

FIG. 6 is a sectional front view of the detail of Fig. 5; FIGS. 7a to 7e show pairs of views according to front and transverse sections of the device of Fig. 1 during a typical work cycle;

FIG. 8 illustrates the unfolding in a plane of the helical surfaces belonging to the detail of Fig. 5.

Detailed description of a preferred example of embodiment With reference to the cited figures, a switching device according to the invention, globally indicated with the number 1, can be used in all systems for which the presence of a bistable switching of a electrical circuit.

For example, the device 1 can be applied to an industrial or service plant, for example a control system of an elevator cabin for the activation of the relative lighting system located inside the elevator shaft.

Device 1 is intended to be connected to a cable F, a tie rod or similar organ to allow switching by means of manual or automatic actuation even remotely, as exemplified in Fig. 1.

As can be seen from the same Fig. 1 and from Fig. 2, a cable switching device 1 comprises a first box-like body 2 housing at least one switch inside it, simply schematized in the figures and indicated with 3, configured to be connected to at least an electrical circuit, not shown.

Switch 3 will not be described in detail here as it can be configured according to commonly used schemes. Generally, there will be at least one mobile contact capable of interacting with at least one fixed contact which can be connected to the electrical circuit for switching an electrical load.

The switch 3 can therefore be switched between a first condition, in which the electric circuit is closed, and a second condition, inverse with respect to the first, with the circuit open.

In an alternative application, not illustrated, the device 1 can be used to perform the bistable circuit switching between two distinct electric circuits, for example a primary circuit and an auxiliary circuit of the electrical system served.

In this case, the switch 3 may comprise at least one pair of fixed contacts which can be connected to the terminals, respectively, of the main circuit and of the secondary circuit, and at least one moving contact which can be brought selectively and alternatively into contact with one of the fixed contacts. of the couple.

The switch 3 can thus be switched between a first condition in which the main circuit is closed and the secondary circuit open, and a second condition which is inverse to the first.

The device 1 according to the invention further comprises a switching unit with bistable operation, globally indicated with 4, operatively associated with the switch 3 to promote the transition between the open and closed circuit condition.

The switching unit 4 essentially comprises an actuator 5 which can be associated with an actuation cable F and means 6 for guiding the actuator 5 between a first A and a second B stable operating position in which the switch 3 is stably maintained, respectively, in the open condition and in the closed condition.

According to a peculiar characteristic of the invention, the switching unit 4 is removably connected to the box-like body 2. There are also provided locking means 7 of the switching unit 4 capable of keeping it constantly assembled in the first A or in the second position B.

In this way it will be possible to remove the entire switching unit 4 from the box-like body 2 in a unitary manner, keeping it assembled and ready to be applied also to a box-like body 2â € ™, 2â € different from the first 2, as shown in Fig. . 3.

The box-like bodies 2, 2 ', 2' may be provided with respective switches 3, 3 ', 3' not necessarily identical to each other.

The locking means 7 may comprise a hollow head 8 housing the bistable switching unit 4 and having a portion 9 for the removable anchoring thereof to the box-like body 2.

As can be seen from Fig. 4, the head 8 may be substantially prismatic or cylindrical, with upper 10 and lower 11 end portions and a central portion 12 that can be separated from each other to simplify the assembly operation of the switching unit 4 .

The head 8 may also be provided with sealing gaskets, not shown, to prevent the entry of water or other particles into it.

The different portions 10, 11, and 12 of the head 8 can be kept assembled together by any type of coupling.

As in the example of the figures, preferred but not exclusive to the invention, the head 8 may have a first series of peripheral through holes 13, four in the example illustrated, which cross the entire head 8 in an axial direction in correspondence with of its peripheral anchoring portion 9.

When applying the switching unit 4 to the box-shaped body 2, the holes 13 of the first series can be aligned with corresponding axial holes 14 of a second series made on the upper face 15 of the box-shaped body 2.

The removable anchoring of the bistable switching unit 4, kept assembled by the head 2, can be made by means of screws 16, pins or similar means.

However, it will appear clear to a person skilled in the art that both the shape of the body 2 and that of the head 8 may also differ significantly from those illustrated, without thereby departing from the scope of protection of the present invention.

The cavity 17 defined internally to the head 8 can be substantially cylindrical with a lateral surface 18 which will define a longitudinal axis L.

The cavity 17 can be configured and suitably sized to house and radially hold the entire switching unit 4, as shown in Fig. 2.

The guide means 6 may be substantially axial, that is, configured to guide the actuator 5 between the first A and the second B stable position along the longitudinal axis L.

In this way the actuator 5, following each traction exerted through the cable F, will translate axially with a first stroke Ci from bottom to top and subsequently from top to bottom with a second stroke C2.

Preferably, the guide means 6 can be configured so that the passage of the switching unit 4 from the first A to the second B stable position, and vice versa, always takes place in correspondence with the first axial stroke Ci of the actuator 5.

In Figs. 5 and 6 illustrate a preferred, but not exclusive, configuration of the guide means 6 belonging to the switching unit 4.

According to this configuration, the guide means 6 will comprise a substantially cylindrical and tubular slider 19 placed inside the cavity 17.

The slider 19 can be rotatably mounted on the actuator 5 and can slide axially in the cavity 17. Preferably, the actuator 5 will be made integral with the slider 19 in the axial translation, by means of special radial flanges 20, 21 of the same actuator 5 or equivalent means. , for example o-rings or similar joints.

The actuator 5 may be substantially cylindrical and may have a lower portion 22 adapted to interact with the switch 3 and an upper portion 23 which can be anchored to the actuation cable F according to known methods.

By way of example, the lower portion 22 of the actuator 5 can be sized to fit into a passage 24 made in the box-like body 2 to allow interaction with the switch 3.

The upper portion 23 may have an end 25 radially widened to define a step 26 protruding radially with respect to the rest of the body of the cylindrical actuator 5 and provided with an eyelet 27 to which one end of the drive cable F can be anchored.

It should be noted that, in this text, the terms â € œsuperiorâ € and â € œlowerâ € and â € œtopâ € and â € œbass "are used only to define a relative position between the different parts of the device 1 according to the invention and are not to be understood with absolute value.

In fact, the device 1 can be used according to any orientation in space, without departing from the scope of protection of the present invention.

On the lateral surface 28 of the slider 19 there may be one or more radial projections 29, preferably directed outwards.

In the example illustrated in the attached figures, the slider 19 has four identical and angularly equidistant protrusions 29 which can be arranged in correspondence with the lower part of the slider 19, so as to ensure a balanced attitude and a homogeneous movement to the actuator 5.

The guide means 6 may comprise at least a pair of axially offset helical surfaces to define an upper helical surface 30 and a lower helical surface 31.

These helical surfaces 30, 31 will be able to delimit inside them a substantially helical guide path for the radial projections 29 of the slider 19.

In particular, inside the cavity 17 of the head 8, in correspondence with its lower portion 11, one or more peripheral tooth formations 32 substantially similar to each other and angularly equidistant may be provided to define a plurality of peripheral channels 33 substantially axial .

Each tooth formation 32 may have a pair of lower helical surfaces 31, 31â € ™ of predetermined pitch. The lower helical surfaces 31, 31â € ™ may face respective upper helical surfaces 30, 30â € ™ associated with the median portion 12 of the head 8.

The locking means 7 may comprise one or more substantially transverse lower abutment surfaces 34 which terminate respective lower helical surfaces 31.

The lower abutment surfaces 34 can be interposed between two lower helical guide surfaces 31, 31 'and connected to the other helical surface 31' by means of an axial section 35 so as to create a concavity to house one of the protrusions 29 of the slider 19 and block the axial sliding downwards of the latter.

The upper guide surfaces 30, 30 'can be joined by axial portions 36 which will define further concavities suitable for limiting the upward axial translation of the slider 19, and therefore of the actuator 5 integral with it in translation.

The pitches of the propellers defined by the guide surfaces 30, 30â € ™; 31, 31â € ™ belonging to the same pair may differ from each other and be chosen according to the axial and angular stroke to be imparted to the slider 19 for a single actuation.

The arrangement of four tooth formations 32 will allow the execution of four complete work cycles of the switching unit 4 within a complete rotation of 360 ° by the cursor 19.

The expression â € œcompleted work cycleâ € means the passage of the switching unit 4 from the first to the second operating position and the subsequent return to the first position.

The locking means 7 may also have a substantially transverse upper abutment surface 37 suitable for interacting with the enlarged end 25 of the upper portion 23 of the actuator 5 to limit its axial translation downwards.

The upper abutment surface 37 can be substantially annular and define the upper face of the head 8.

In this case, as can be seen from the figures, it may have a central opening 38 with a diameter sufficient to allow partial entry of the cylindrical actuator 5 but smaller than the diameter of the enlarged end 25.

Peripherally to the actuator 5, in correspondence with its central portion 12, an elastic return element 39 can be keyed having a first end 40 acting on the upper abutment surface 37 and a second end 41 acting on the projections 29 of the slider 19.

The elastic element 39 will serve to bring the protrusions 29 of the slider 19 from one of the upper helical surfaces 30, 30â € ™ to the corresponding lower helical surface 31, 31 â € ™ or in one of the axial channels 33, depending on the position A, B starting, following the traction of the actuator 5 by means of the cable F. Furthermore, its elastic action will counteract the traction action exerted by the cable F.

The elastic element 39 can be a helical spring having end coils engaged in respective bushings 42, 43 and can be preloaded with a predetermined load.

In Figs. 7a-e illustrates a device 1 according to the invention with the switching unit 4 engaged in a typical work cycle.

In particular, Fig. 7a illustrates the switching unit 4 in the first position A, to which an operating condition for the switch 3 may correspond, for example that of open circuit.

Fig. 7b illustrates the same switching unit 4 in an unstable intermediate position following a first pull of the actuator 5 exerted through the cable F, to then pass into the second stable position B, illustrated in Fig. 7c, at which another operating condition will correspond to switch 3, for example that of closed circuit.

Fig. 7d shows again the switching unit 4 in a further unstable intermediate position following a second traction exerted through the cable F to bring the switching unit 4 back to the first stable position of Fig. 7e .

From the cross sections associated with each of the front sections it is instead possible to observe the rotation of the individual protrusions 29 of the slider 19 following each traction action exerted on the actuator 5.

Fig. 8 represents the unwinding in the plane of the helical guide surfaces 30, 30â € ™; 31, 31 â € ™. In the same figure, with a dashed line, the helix guide path followed by a single projection 29 during a typical work cycle is traced.

In the following, for the description of a typical work cycle, a single projection 29 of the slider 19 will be considered, it being understood that all the other radial projections 29 possibly present will behave in a substantially similar manner.

From Figs. 7 and 8 it is observed that, upon the first traction on the cable F, the slider 19 will slide axially in a manner integral with the cable F and, at the same time, the projection 29, initially housed in the axial channel 33, will slide on a corresponding inclined plane defined by one of the upper helical surfaces 30 up to the stop point defined by the upper concavity comprised between the axial portion 36 and the upper guide surface 30.

In this way the cursor 19 will be forced to rotate by a certain angle a, as evidenced by the rotation of the transverse axes X, Y visible from the comparison of the cross sections of Figs. 7a and 7b.

When the cable F is released, the slider 29 will slide in the opposite direction, pushed by the elastic return force of the spring 39, making the projection 29 slide on one of the lower helical surfaces 31 up to the stop point defined by one of the lower abutment surfaces 34 , by guiding the cursor 29 in rotation for a further angle β-Î ± as visible in the cross section of Fig. 7c.

Following a new traction, the projection 29 will slide on a further upper helical surface 30 'adjacent to the previous one up to the next stop point defined by one of the upper concavities. Consequently, a further rotation γ-β of cursor 29 will be determined.

Upon subsequent release of the cable F, the slider 19 will move axially under the action of the spring 39 and its radial projection 29 will slide on the lower helical guide surface 31â € ™ adjacent to the previous one to enter another axial channel 33â € ™ , leaving the slider 19 free to slide until the enlarged head 25 of the actuator 5 comes into contact with the upper abutment surface 37 of the head 8. In the example illustrated, during this complete closing-opening cycle, the slider 19 will undergo an overall rotation with an angle Î ́ of 90 °, thus placing itself in a position that will allow the start of the next cycle.

The cycle can therefore be repeated every time it is necessary to close or open the electrical circuit, for example to switch on or off the emergency lights in an elevator shaft.

From what has been described above it is evident that the invention achieves the intended purposes and in particular that of providing a cable switching device which can be manufactured in a modular manner for a simple replacement of one or more of its components, thus not requiring the replacement of the entire device if only some parts need to be replaced.

The device according to the invention is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept expressed in the attached claims. All the details can be replaced by other technically equivalent elements, and the materials can be different according to the requirements, without departing from the scope of the invention.

Even if the device has been described with particular reference to the attached figures, the reference numbers used in the description and in the claims are used to improve the intelligence of the invention and do not constitute any limitation to the scope of protection claimed.

Claims (11)

R I V E N D I C A Z I O N I 1. A bistable wire rope switching device, comprising: - a box-shaped body (2) able to house at least one switch (3) which can be connected to a corresponding electrical circuit; - a bistable switching unit (4) operatively associated with said at least one switch (3) to promote its switching between a closed condition and an open condition of said circuit; wherein said unit (4) comprises an actuator (5) which can be associated with an actuation cable (F) and guide means (6) for guiding said actuator (5) between a first (A) and a second (B) operating positions buildings corresponding respectively to said opening and closing conditions of said at least one switch (3); characterized in that said unit (4) is removably connected to said box-like body (2), locking means (7) being provided which are capable of maintaining said unit (4) constantly assembled with said actuator (5) selectively in said first ( A) or in said second (B) stable operative position to allow its unitary removal from said box-like body (2). 2. Device according to claim 1, characterized in that said locking means (7) comprise a hollow cylindrical head (8) suitable for housing said switching unit (4) and having a portion (9) for the removable anchoring of the latter to said box-like body (2). 3. Device according to claim 2, characterized in that the cavity (17) of said head (8) is substantially cylindrical with a lateral surface (18) defining a longitudinal axis (L) and configured to house and radially hold said unit switching (4). 4. Device according to claim 2 or 3, characterized in that said guide means (6) are substantially axial and configured to guide said switching unit (4) from said first position (A) to said second position (B) and vice versa following a unidirectional axial translation of said actuator (5). 5. Device according to any one of the preceding claims, characterized in that said guide means (6) comprise a slider (19) rotatably mounted on said actuator (5) and axially sliding in said cavity (17), said slider (19) being provided on its lateral surface (28) with at least one radial projection (29). 6. Device according to claim 5, characterized in that said guide means (6) comprise at least a pair of axially offset helical surfaces (30, 31) to define a substantially helical guide path for said at least one radial projection (29) . 7. Device according to claim 6, characterized in that said locking means (7) comprise at least a substantially transverse lower abutment surface (34) connected to the lower helical surface (30) of said at least one pair to block the axial sliding towards the bottom of said slider (19). 8. Device according to claim 7, characterized in that said guide means (6) have a plurality of said pairs of helical surfaces (30, 31; 30â € ™, 31 â € ™) angularly offset, said locking means ( 7) presenting a plurality of said lower abutment surfaces (34) connected to corresponding lower helical guide surfaces (31). 9. Device according to any one of the preceding claims, characterized in that said actuator (5) is substantially cylindrical and has a lower portion (22) adapted to interact with said at least one switch (3) and an upper portion (23) which can be anchored to said drive cable (F). 10. Device according to claim 9, characterized in that said tubular cavity (17) has a substantially transverse upper abutment surface (37) adapted to interact with said upper portion (23) of said actuator (5) to limit its axial translation downward. 11. Device according to claim 10, characterized in that it comprises an elastic return element (39) having a first end (40) acting on said upper abutment surface (34) and a second end (41) acting on said slider ( 19) to force said at least one radial projection (29) to pass from one of said upper helical surfaces (30, 30 ') to the corresponding lower helical surface (31, 31') in response to a traction of said actuator (5 ) by means of said cable (F).