Remote safety release device for safety switch and safety switch including release device

Abstract

The remote safety release device for a safety switch comprises: an actuator, adapted to interact with a locking mechanism of an associated switch to force release, adapted to move between a non-working position without interaction with the locking mechanism and at least one working position interacting with the locking mechanism; a remote control device, adapted to be driven by an operator to remotely control the actuator to cause it to move from the non-working position to the working position; a transmission mechanism, adapted to transmit force from the remote control device to the actuator to move the actuator according to a command given by the operator. The transmission mechanism is adapted to apply a first request to the actuator to automatically transition from the non-working position to the working position, the remote control device applies a second control request to the actuator, the second control request is opposite to the first request and has at least the same value to cancel the first request to keep the actuator in the non-working position, and in the absence of the second request, the actuator is allowed to automatically transition from the non-working position to the working position to release the locking mechanism.

Description

Technical Field

[0001] The invention finds application in the field of electrical equipment for industrial use and is particularly intended for use in remote safety release devices applied to safety switches, in particular of the type designed for protecting movable protection devices (such as barriers, guards, service panels or the like) for controlling access to industrial machines and installations, the remote release device allowing the operator to release the switch even remotely. Background Art

[0002] Known switches for controlling access to barriers and / or security perimeters of industrial machines and facilities typically comprise a switch device anchored to a fixed portion of the entrance and an actuator device anchored to a movable portion.

[0003] The purpose of these switches is to block the system when an entrance is opened for obvious safety reasons, while activating one or more signaling or service circuits that will also keep the entrance blocked if the system is not in a safe state.

[0004] Similarly, a switch can allow a machine or system to be restarted immediately upon closing an access point, unless a situation occurs that requires specific operator intervention.

[0005] The commands for switching devices for opening and closing the power supply circuit of a machine or a system can be executed by actuators of mechanical or electronic type.

[0006] In the first case, a key actuator is usually associated with a movable device and is adapted to fit into a slot of a switch device to interact with a mechanism for actuating a switch device for opening / closing the power circuit and any auxiliary circuits.

[0007] At the same time, the key actuator engages with a locking slide controlled by an appropriate locking / unlocking mechanism, the function of which is to keep the actuator in the slot to prevent the portal from being opened in unsafe conditions and to prevent the same actuator from coming out due to vibrations transmitted by the portal.

[0008] An electronically operated switch, such as that described in application WO2015083143 in the name of the same applicant, provides that the two devices are equipped with respective electronic circuits adapted to interact with each other via presence signals sent by circuits associated with the actuator device so as to allow the main power circuit to be opened or closed depending on their mutual distance.

[0009] Typically, also for the second type of switch, the movable actuator device is provided with a centering and retaining element adapted to be inserted into a suitable hole in the fixed switching device, within which hole there is a locking / unlocking mechanism with a slide which will engage the centering pin to prevent its unauthorized extraction.

[0010] Whatever the specific configuration of the switch, the release of the holding element, whether the actuator itself or the aforementioned centering and holding element, can be produced by a special electrical command sent to the control mechanism of the element or given by an auxiliary mechanical emergency release command placed directly on the casing of the switchgear and suitable for acting directly on the holding element.

[0011] Some switches can also be equipped with an additional remotely operated emergency release device.

[0012] This solution is often used in situations where it is impossible or undesirable to place the switch in a location that is easily accessible to the operator.

[0013] The remote release device generally comprises a housing which is integrated or adapted to be applied to the casing of the switching device and inside which there is an auxiliary actuator adapted to interact with the locking / unlocking mechanism to remove the locking of the retaining element according to a command given remotely through the actuator.

[0014] An example of a safety switch with a remote release device is described in DE 10 2006 020 500, in which remote activation of the auxiliary release device is performed by pulling a Bowden cable.

[0015] A common disadvantage of the known solutions is that these known release devices do not have a system allowing immediate release of the holding mechanism in the event of damage or failure of the remote control (eg the pulling cable).

[0016] As a result, a malfunction of the remote control becomes the cause of a potentially dangerous situation, rendering the corresponding switch potentially unsafe. Summary of the invention

[0017] The object of the present invention is to overcome the above-mentioned drawbacks and provide a remote safety release device which can be applied to a safety switch and has the characteristics of high efficiency and relative cost-effectiveness.

[0018] A specific object is to provide a remote safety release device suitable for use with a safety switch and designed to automatically operate the locking / unlocking mechanism system of the switch with which it is associated in the event of damage or failure of its actuator, so as to move the switch under safe conditions.

[0019] Yet another specific object is to provide a remote safety release device suitable for a safety switch, the damage or failure of which will not cause a hazardous situation to the system in which the switch is applied.

[0020] These objects, as well as other objects that will become more apparent hereinafter, are achieved by a remote safety release device suitable for a safety switch and, according to the independent claim, comprising: an actuator adapted to interact with a mechanical locking mechanism of an associated switch to force its release, the actuator being adapted to move between a non-working position in which it does not interact with the locking mechanism and at least one working position in which it interacts with the locking mechanism; a remote control device adapted to be driven by an operator to remotely control the actuator and facilitate its movement from the non-working position to the working position for its interaction with the locking mechanism and subsequent release; a transmission mechanism adapted to transmit a force from the control device to the actuator in accordance with a command given by the operator to facilitate the movement of the actuator from the non-working position to at least one working position.

[0021] According to a specific feature of the present invention, the transmission mechanism is suitable for applying a first request or induction to the actuator to facilitate its automatic passage from the non-working position to the working position, and the remote control device is designed to continuously apply a second control request or induction to the actuator in the absence of remote control, the second control request being opposite to the first request and having a value at least equal to canceling the first request and keeping the actuator in the non-working position, so as to allow the actuator to automatically pass from the non-working position to the working position to release the locking mechanism in the absence of the second request.

[0022] Thanks to this combination of features, if the remotely operable control device is broken, damaged or fails, the control request to keep the actuator in the inoperative position (ie not interacting with the locking mechanism) will become ineffective.

[0023] Thus, due to the demand constantly exerted by the transmission mechanism on the actuator, the transmission mechanism will automatically move the actuator into the working position, ie the position in which the actuator interacts with the locking mechanism, causing the locking mechanism to release.

[0024] The block will therefore be removed, resulting in a situational or timed shutdown of the plant or its hazardous parts and a simultaneous release of the access points to return the system to a safe state.

[0025] According to another aspect of the present invention, there is provided a safety switch according to the claims.

[0026] Advantageous embodiments of the invention are obtained from the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Further features and advantages of the invention will become more apparent in view of the detailed description of some preferred but not exclusive embodiments of a remote safety release device and a safety switch comprising the same, by means of non-limiting examples and the accompanying drawings, in which:

[0028] Figure 1 is a perspective view of a switch with a safety release device according to a first preferred embodiment of the present invention, the switch is applied to an entrance of a security perimeter, wherein the entrance is in an open entrance state;

[0029] Figure 2 yes Figure 1 A perspective view of a portion of a switch;

[0030] Figure 3 yes Figure 1 a perspective view of a portion of a switch with a safety release device not assembled;

[0031] Figure 4 is an exploded perspective view of a safety release device of a first preferred embodiment;

[0032] Figure 5 yes Figure 4 A side sectional view of a safety release device applied to a switch and in a non-operating state;

[0033] Figure 6 yes Figure 4 Rear view of the safety release device in three different working states;

[0034] Figure 7 yes Figure 4 Side view of the safety release device in three different working states;

[0035] Figure 8 yes Figure 4 Side sectional views of the safety release device in three different working states;

[0036] Fig. 9 is based on Figure 4 A three-dimensional diagram of a driving element of a safety release device in two different working states;

[0037] Fig.10 yes Fig. 9 Detailed cross-sectional views in two different working states;

[0038] Fig.11 yes Figure 4 Rear view of the safety release after rotation according to three configurations;

[0039] Fig.12 is a partially exploded perspective view of a switch associated with a safety release device of a second preferred embodiment;

[0040] Fig.13 yes Fig.12 An exploded perspective view of the safety release device;

[0041] Fig.14 yes Fig.12 A side sectional view of a safety release device applied to a switch and in a non-operating state;

[0042] Fig.15 yes Fig.12 Side sectional views of the safety release device in three different working states;

[0043] Fig.16 is a partially exploded perspective view of a switch associated with a safety release device of a third preferred embodiment;

[0044] Fig.17 yes Fig.16 An exploded perspective view of the safety release device;

[0045] Fig.18 yes Fig.16 Side sectional view of the safety release device in two different working conditions. DETAILED DESCRIPTION

[0046] Referring to the accompanying drawings, preferred but non-exclusive embodiments of a safety switch for controlling access to industrial machinery and facilities and associated with a remote safety release are shown according to some preferred but non-exclusive embodiments.

[0047] The switch is generally designed for use preferably, but not exclusively, in connection with barriers or movable protective panels designed to prevent unsafe access to machinery or industrial plants during operation.

[0048] Typically, the switch will be designed to apply protection at an access point thereof to interrupt operation of the machine or facility in a substantially immediate or timed manner when a door or panel enclosing that access point is opened.

[0049] Figure 1 A typical application is shown, where a switch (globally denoted by 1) is applied to entrance A of a protective barrier.

[0050] The switch 1 comprises a switchgear 2 adapted to be fixed to a fixed frame F of an inlet A and connected in a known manner to one or more electrical and / or electronic circuits for powering and / or controlling main circuits and / or service and emergency circuits (not shown).

[0051] The method for connecting the switching device 2 to these circuits is of a known type and does not form part of the present invention and will therefore not be disclosed in more detail hereinafter.

[0052] Instead, on the movable part M of the access A there is mounted an actuator device 3 adapted to interact with the switch device 2 after the access A has been opened or closed, to determine the opening or closing of one or more circuits according to the typical mode of this type of safety switch.

[0053] The switchgear 2 comprises a casing 4 adapted to be anchored to a fixed part F of an inlet A to be controlled and to house switching devices for controlling one or more control and / or service circuits of a machine or installation.

[0054] The switch means are not visible in the figure because they are inside the housing 4, and the switch means can be selected from those commonly used in the art and can also vary according to the function of the switch without particular limitation.

[0055] There will also be a drive device (not shown) inside the housing 4, which is suitable for interacting with the switching device when the entrance A is opened / closed, and is used to open / close one or more circuits of the machine or facility after the interaction between the switching device 2 and the actuator device 3, which is also implemented in this case according to known technology.

[0056] Examples of such switches are disclosed in WO2017208124 or WO2015083143 (both in the name of the same applicant) and provide that the actuator device 3 is provided with a retaining and centering element 5, which extends from the actuator device 3 to engage with a centering hole 6 in the housing 4 when the inlet A is closed.

[0057] Inside the switchgear 2 there is also a locking mechanism with a sliding pin (not shown) which will engage the retaining element 5 to lock it by mechanical interference and prevent it from being even only partially pulled out when the installation is in an unsafe state.

[0058] The technical features of the locking mechanism are not described in detail below, as they are not important for the present invention.

[0059] The switch 1 may also be provided with an auxiliary release command device placed directly on the housing, such as a key release device 8 in the figure, to manually unlock the locking mechanism.

[0060] The switch 1 shown in the figures is of the electronically operated type, ie the action of the actuator device 3 on the switching device will be controlled by an electronic signal transmitted to the switching device according to known methods (for example in the previously cited WO 2015083143).

[0061] To this end, the switching device 2 may comprise a receiver element, for example an antenna of the RFID type, housed in an appropriate position within the same housing 4 and suitably arranged and designed to receive a remote control signal or presence signal sent by a transmitter or transponder element housed in the movable actuator device 3 (when the actuator device 3 is at a predetermined minimum distance from the switching device 2 so that the entrance A is considered closed under safety conditions).

[0062] In particular, the transponder (not visible in the picture) will be equipped with a tag with an identification code that must be recognized by the antenna to allow the machine or facility to start.

[0063] The identification of the code can be unique or universal, depending on whether you want to switch with high or low coding.

[0064] However, according to an embodiment not shown, the switch 1 may also be electromechanically operated, i.e. having an actuator device 3 which will be provided with a mechanical actuator (e.g. a key) which will be inserted into a suitable slot to mechanically interact with the switching device while engaging a sliding pin of the locking mechanism.

[0065] Figure 2 and Figure 3 A switching device 2 according to a first embodiment is shown, which belongs to an electronically operated switch 1 and is associated with a remote safety release device 9 .

[0066] In particular, the remote safety release device 9 comprises a housing 10 suitable for being anchored in a fixed but possibly removable manner to the casing 4 of the switchgear 2, corresponding to an appropriate channel 11 provided in the upper head 12 of the casing 4, and specifically positioned as follows: allowing direct access to the locking mechanism and interaction with it, so as to directly or indirectly operate the release pin of the retaining element 5.

[0067] In the illustrated embodiment, the safety release device 9 will operate against the upper end of the locking slide 7, which is made in one piece or connected to a sliding pin, which preferably rigidly locks the retaining element 5 so that when the slide 7 translates, a translation of the retaining element 5 will occur.

[0068] The release device 9 comprises a movable actuator 13 which is arranged in the housing 10 to interact with the mechanical locking mechanism of the switch and to cause its positive release.

[0069] In particular, the actuator 13 will be adapted to move between an inoperative position in which it does not interact with the slide 7 of the locking mechanism and an operative position in which it interacts with the slide 7 of the locking mechanism.

[0070] The safety release device 9 is also provided with a remote control device 14 operable by an operator to remotely control the actuator 13 and facilitate its movement between the above-mentioned positions for subsequent interaction with the slide 7 of the locking mechanism and its subsequent release (as described more clearly below).

[0071] The connection between the actuator 13 and the remote control device 14 will be obtained by a suitable transmission mechanism 15 located in the housing 10 , which will be designed to transmit forces from the remote control device 14 to the actuator 13 to facilitate the movement of the actuator 13 , following the commands given by the operator.

[0072] Furthermore, the transmission mechanism 15 will be connected to the actuator 13 to impose thereon a first request suitable for facilitating an automatic transition from the inoperative position to the operative position.

[0073] At the same time, the remote control device 14 will be designed to constantly exert on the actuator 13, without remote control, a second control request opposite to the first request and having a value at least equal to the first request in order to disable it and thus keep the actuator 13 in the inoperative position.

[0074] from Figure 4 Exploded diagram and Figure 5 As can be seen from the cross-sectional view, the actuator 13 includes an unlocking pin 16, which is movable in the housing 10 and has a first end 17 and a second end 18 connected to the transmission mechanism 15, the second end 18 being suitable for protruding outward from the housing 10 to be assembled into the head 12 of the switch device 2 through an appropriate channel 11 and interacting with the slider 7 of the locking mechanism.

[0075] In this configuration, the movable unlocking pin 16 would be rotatably mounted in the housing 10 to rotate about its central axis.

[0076] Furthermore, the transmission mechanism 15 comprises a preload elastic element 19 which is defined by a spring coiled around the unlocking pin 16 and which is preloaded with the first request so as to continuously exert the first request on the movable unlocking pin 16 in a direct or indirect manner.

[0077] The second end 18 of the transmission mechanism 15 will be appropriately formed to have an axial protrusion 20, which is suitable for interacting with the slider 7 of the locking mechanism after the unlocking pin 16 is rotated in any direction, and its construction will be such that when the unlocking pin 16 is in the non-working position, it will be spaced apart from the slider 7.

[0078] The operation of the safety release device 9 will be Figure 6 , 7This becomes more clearly apparent in comparison with 8 , which shows, from left to right, the safety release device 9 in a state in which the unlocking pin 16 is not activated and is therefore in a non-working position, in a state in which the unlocking pin 16 is operated by the remote control device 14 and is therefore in a first working position, and finally in a state in which the remote control device 14 no longer applies a control request (for example due to damage or a malfunction, as a result of which the unlocking pin 16 will be moved to a further working position by the elastic element 19).

[0079] In the embodiment shown, the remote control device 14 comprises a traction element 21, such as a rope, cable or the like, one end of which is connected to the transmission mechanism 15 and the other end is suitable for being fixed to a drive element 30, such as a knob, mushroom button or other element fixed to a fixed bracket.

[0080] An example of a mushroom-shaped drive element 30 is shown in Fig. 9 , where it is shown in a non-actuated state.

[0081] exist Fig.10 In the figure, on the contrary, the mushroom-shaped drive element 30 can be seen both in the inactive (left side) and activated (right side) situations.

[0082] According to this configuration, the drive element 30 comprises a box-shaped body 31 suitable for being applied to the fixed support 40 and housing a bistable lever 32 connected to one end of the traction element 21 .

[0083] The movement of the lever system 32 and the subsequent traction of the traction element 21 will be generated by actuation (in particular by pressure) of a movable control element 33 (for example a mushroom button) which will be connected to the lever system 32 at its non-pivoting end.

[0084] The connection between the traction element 21 and the transmission mechanism 15 converts the linear traction movement of the traction element 21 into a rotational movement of the unlocking pin 16 .

[0085] The traction element 21 is also always in a tensioned state, so as to always apply the above-mentioned control request.

[0086] Preferably, the traction element 21 may be provided with a voltage indicator 34 which also allows the voltage to be adjusted.

[0087] For example, from Figure 4 As can be seen more clearly, the voltage indicator 34 is a cam element provided with a cylindrical body which is made integrally with the unlocking pin 16 so as to rotate coaxially therewith.

[0088] The voltage indicator 34 is to be inserted into a special seat in the housing 10 so that one face of its cylindrical body is visible from the outside.

[0089] On this face there will be a reference element 35 , such as a trace, notch, or other distinguishing element, which must be aligned with a reference mark 36 (eg, an arrow) or other reference mark present on the back of the housing 10 .

[0090] Alignment between the reference element 35 and the reference mark 36 will indicate correct tensioning of the transmission 15 .

[0091] In addition, the voltage can be fine-tuned by one or more regulators. For example, the first regulator 37 can be disposed at the end of the traction element 21 close to the housing 10 , and the second regulator 38 can be disposed at the end of the traction element 21 close to the drive element 30 .

[0092] As long as the remote control device 14 exerts its control request, counteracting the thrust of the elastic element 19 , the unlocking pin 16 will remain stationary in its inoperative position in which the axial projection 20 is not in contact with the slide 7 of the locking mechanism.

[0093] If the operator exerts additional traction on the traction element 21 , the elastic element 19 will be further induced, which will cause the unlocking pin 16 to rotate about its axis and thus cause the protrusion 20 to be pushed onto the slide 7 , which will translate downwards, thereby releasing the retaining element 5 of the actuator device 3 .

[0094] In the event that the traction element 21 is damaged or cut and will no longer be suitable for applying the control request, the preloaded elastic element 19 will cause the unlocking pin 16 to rotate in the opposite direction of the previous movement, but always causing the protrusion 20 to act on the slider 7, which in this case will also translate downwards, thereby moving the sliding pin of the release mechanism and releasing the retaining element 5 of the actuator device 3.

[0095] The projection 20 of the unlocking pin 16 can be shaped so as to act on the slide 7 after a rotation of 90° in both directions.

[0096] from Fig.11 It can also be seen that, depending on the positioning requirements of the remote control device 14 and / or the switch device 2 itself, the safety release device 9 can be applied to the housing 4 of the switch device 2 according to different angle orientations, thereby significantly increasing the application flexibility of the release device 9 and the switch associated therewith.

[0097] Preferably, but not exclusively, the housing 10 can be rotated about the central axis of the passage 11 , wherein the unlocking pin 16 is inserted in both directions at a minimum rotation angle of 90°.

[0098] Fig.12A second embodiment of the safety release device 9 is shown, which mainly differs from the previous embodiment in that the connection between the traction element 21 and the unlocking pin 16 is obtained by means of a guide device 22, which is suitable for facilitating the translation of the unlocking pin 16 from the non-working position to the working position after additional traction is applied to the traction element 21 or in the event of an invalid control request.

[0099] In this case, the preloaded elastic element 23 is a linear spring which acts indirectly on the first end 17 of the unlocking pin 16 , while the second end 18 can protrude more or less depending on its position.

[0100] In addition, the second end 18 of the unlocking pin 16 will form an inclined surface, so that its contact with the upper end of the slider 7 will cause the slider 7 to slide downward gradually.

[0101] The operation of the safety release device 9 is Fig.15 , in which, from left to right, the unlocking pin 16 is respectively in a state in which it is not activated and is therefore in the non-working position, in a state in which it is operated by the remote control device 14 and is therefore in the first working position, and finally in a state in which the remote control device 14 no longer applies a control request (for example due to damage or malfunction), as a result of which the unlocking pin 16 will always be moved into the working position by the linear spring.

[0102] The translational movement will be generated by the action of the guide element 24 which is connected to one end of the traction element 21 to be dragged by the one end of the traction element 21 inside the housing 10 and the elastic element 23 which will act on the traction element 21 .

[0103] The guide element 24 will be provided with a shaped guide rail 25, and the first end 17 of the unlocking pin 16 will slide in the guide rail 25, and the construction of the guide rail 25 will make the unlocking pin 16 always translate in the same direction, that is, from the inoperative retracted position in the housing 10 to the extracted operative position, when the guide element 24 translates in a first direction due to an additional traction force, or when the guide element 24 translates in the opposite direction due to the thrust of the elastic element 23.

[0104] Also for this embodiment, the traction element 21 will have one end connected to the transmission mechanism 15 and an opposite end suitable for being fixed to the drive element 30 (such as a knob, mushroom button or other element), and the drive element 30 is anchored to the fixed support in a manner equivalent to the technology described in the previous configuration; for example, the drive element 30 can be the same mushroom-shaped element as described above.

[0105] Also with this configuration, provision can be made for the presence of a voltage indicator and a fine-tuning regulator of the traction element 21 .

[0106] For example, the tensioning indicator can be the same translation guide element 24, on whose outer surface a drawn scale is displayed, with a rising-falling profile in the figure, with a reference element 35 and visible from the outside through a window 39 arranged on a visible face of the housing 10, corresponding to which a reference mark 36 or other reference mark appearing on the rear surface of the housing 10 will be provided.

[0107] Also in this example, alignment between reference element 35 and reference mark 36 will indicate proper tensioning of transmission mechanism 15 .

[0108] Fig.16 A third embodiment of a safety release device 9 is shown, which is always applied to the same switching device 2 of the safety switch 1 .

[0109] The safety release 9 differs from the previous ones primarily in that the remote control device 14 is of the oil-powered, pneumatic or hydraulic type or can be operated by another type of fluid and comprises a duct 26 suitable for conveying pressurized fluid to the movable unlocking pin 16 .

[0110] from Fig.18 As can be seen more clearly, the movable unlocking pin 16 slides inside the housing 10 and is shaped so as to define internally (also through a suitable gasket 28 placed around the unlocking pin 16 ) a sealed cavity 27 designed to receive a pressurized fluid.

[0111] The elastic element 29 is in turn defined by a linearly operating spring which acts on the first inner end 17 of the unlocking pin 16 to push it outwards.

[0112] When the release device 9 is not activated, the pressure generated by the remote control device 14 will counteract the stress generated by the linear operating spring, thereby maintaining the unlocking pin 16 in its inoperative retracted position completely housed in the housing 10 or slightly protruding so as not to interact with the slide 7 of the locking mechanism.

[0113] In order to actuate the unlocking pin 16 , it is sufficient to reduce or interrupt the control pressure so that the linear actuating spring pushes the unlocking pin 16 into the working position.

[0114] Similarly, if the remote control device 14 malfunctions or becomes damaged, the loss of pressure will result in immediate actuation of the unlocking pin 16 due to the thrust of the linear operating spring.

[0115] The second end 18 of the unlocking pin 16 is formed into an inclined plane so that it contacts the upper end of the slider 7 and slides downward gradually.

[0116] Last but not least, for this embodiment, provision may also be made for the presence of voltage indicating means (not shown).

[0117] It can be clearly seen from the above that the safety release device and the switch according to the present invention achieve the intended purpose.

[0118] The release device and switch according to the invention are susceptible to numerous modifications and variations, all of which fall within the inventive concept expressed in the appended claims. Without departing from the scope of protection of the invention, all details may be replaced with other technically equivalent elements, and the materials may differ as required.

Claims

1. A remote safety release device for a safety switch, the safety switch being used for access control of industrial machines and facilities, wherein the safety switch (1) comprises a housing (4) accommodating a locking mechanism of the access, the remote safety release device comprising: - an actuator (13) adapted to interact with a locking mechanism of an associated safety switch (1) to cause a positive release of said locking mechanism, said actuator (13) being adapted to move between an inoperative position in which it does not interact with said locking mechanism and at least one operative position in which it interacts with said locking mechanism; - a remote control device (14) adapted to be driven by an operator to remotely control the actuator (13) and cause the actuator to move from the inoperative position to the operative position, so as to facilitate the interaction of the actuator with the locking mechanism and the subsequent release of the locking mechanism; - a transmission mechanism (15) adapted to transmit a force from the remote control device (14) to the actuator (13) in accordance with a command given by the operator, so as to facilitate the movement of the actuator (13) from the non-operating position to the operating position; The transmission mechanism (15) is suitable for applying a first request to the actuator (13) to promote its automatic transition from the non-working position to the working position, and the remote control device (14) is designed to continuously apply a second control request to the actuator (13) in the absence of a remote control command, wherein the second control request is opposite to the first request and has at least an equal value to cancel the first request and keep the actuator (13) in the non-working position, thereby allowing the actuator (13) to automatically transition from the non-working position to the working position in the absence of the second control request to release the locking mechanism.

2. The safety release device according to claim 1, characterized in that: The invention comprises a housing (10) which is suitable for being anchored to the housing (4) of the safety switch (1) in a fixed manner, and the housing (10) internally accommodates the actuator (13) and the transmission mechanism (15).

3. The safety release device according to claim 2, characterized in that: The actuator (13) comprises an unlocking pin (16) which is movable in the housing (10) and has a first end (17) connected to the transmission mechanism (15) and a second end (18), the second end (18) being adapted to protrude from the housing (10) when the unlocking pin (16) is in an operating position interacting with a locking mechanism of the safety switch (1).

4. The safety release device according to claim 3, characterized in that: The actuator (13) comprises an elastic element (19, 23, 29) which is preloaded with the first request to continuously apply the first request to the unlocking pin (16).

5. The safety release device according to claim 4, characterized in that: The remote control device (14) comprises a traction element (21), one end of which is connected to the transmission mechanism (15) and the other end is suitable for being fixed to a drive element (30), the drive element (30) being connected to a fixed support (40), the traction element (21) being continuously tensioned by the second control request.

6. The safety release device according to claim 5, characterized in that: The drive element (30) comprises a box-shaped body (31) suitable for being fastened to the fixed support (40), in which is housed a bistable lever (32) connected at one end to the traction element (21) and associated at the other end with a movable control element (33) suitable for causing the movement of the lever (32) and the subsequent traction of the traction element (21).

7. The safety release device according to claim 5, characterized in that: The unlocking pin (16) rotates around its central axis, and the second end is provided with an axial protrusion (20), which is suitable for interacting with the locking mechanism as the unlocking pin (16) rotates in any direction, and the elastic element preloaded with the first request is a coil spring.

8. The safety release device according to claim 5, characterized in that: The elastic element preloaded with the first request is a linear spring acting on the first end (17) of the unlocking pin (16), and the transmission mechanism (15) includes a guide device (22), which is suitable for promoting the translation of the unlocking pin (16) from the non-working position to the working position after additional traction is applied to the traction element (21) and after the second control request is cancelled.

9. The safety release device according to claim 3 or 4, characterized in that: The remote control device (14) comprises a conduit (26) suitable for conveying a fluid under pressure to the unlocking pin (16) for applying the second control request.

10. The safety release device according to any one of claims 2 to 4, characterized in that: The remote control device (14) comprises a tensioning indicator provided with a reference element (35) adapted to be translated according to the value of the second comparison request so as to align with a reference mark (36) present on the housing (10).

11. A safety switch for controlling access to a machine or industrial facility, comprising: - a switchgear (2) having a housing (4) containing switching devices for one or more circuits of a machine or installation and adapted to be anchored to a fixed part (F) of an inlet (A); - an actuator device (3) adapted to be anchored to a movable part (M) of said inlet (A) so as to interact with said switching means when said inlet (A) is closed; wherein the actuator device (3) comprises a retaining element (5) adapted to interact with a housing (4) of the switchgear when the access opening (A) is closed so as to engage a locking mechanism present in the housing (4) and to prevent removal of the retaining element (5); The switch device (2) is associated with a remote safety release device (9), and the remote safety release device comprises: - an actuator (13) adapted to interact with the locking mechanism to cause a forced release of the locking mechanism, the actuator (13) being adapted to move between an inoperative position in which it does not interact with the locking mechanism and at least one operative position in which it interacts with the locking mechanism; - a remote control device (14) adapted to be driven by an operator to remotely control the actuator (13) and cause the actuator to move from the inoperative position to the operative position, so as to facilitate the interaction of the actuator with the locking mechanism and the subsequent release of the locking mechanism; - a transmission mechanism (15) adapted to transmit a force from the remote control device (14) to the actuator (13) in accordance with a command given by the operator, so as to facilitate the movement of the actuator (13) from the non-operating position to the operating position; The transmission mechanism (15) is suitable for applying a first request to the actuator (13) to promote its automatic transition from the non-working position to the working position, and the remote control device (14) is designed to continuously apply a second control request to the actuator (13) in the absence of a remote control command, wherein the second control request is opposite to the first request and has at least an equal value to cancel the first request and keep the actuator (13) in the non-working position, thereby allowing the actuator (13) to automatically transition from the non-working position to the working position in the absence of the second control request to release the locking mechanism.

12. The switch according to claim 11, characterized in that The housing (4) comprises a head (12) provided with at least one hole (6) for the retaining element (5) and a passage (11) for the actuator (13), the remote safety release device (9) comprising a housing (10) adapted to be fixedly anchored to the housing (4) at the passage (11), the housing (10) accommodating the actuator (13) and the transmission mechanism (15) inside, the actuator (13) comprising an unlocking pin (16) movable in the housing (10) and having a first end (17) connected to the transmission mechanism (15) and a second end (18), the second end (18) being adapted to protrude from the housing (10) to interact with the locking mechanism through the passage (11).

13. The switch according to claim 12, characterized in that The housing (10) is rotatably anchored to the casing (4) to rotate in two directions about the central axis of the passage (11).

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