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EP-4352770-B1 - SAFETY SWITCH FOR GUARDING ACCESSES

EP4352770B1EP 4352770 B1EP4352770 B1EP 4352770B1EP-4352770-B1

Inventors

  • PIZZATO, MARCO
  • ZONTA, SIMONE

Dates

Publication Date
20260506
Application Date
20220304

Claims (12)

  1. A safety switch for monitoring the access to industrial machines and plants, comprising: - a switching device (2) adapted to be anchored to a fixed part of the access to be monitored and housing thereinside switching means for controlling one or more command and/or service circuits of the machine or plant; - a driving device (3) adapted to be anchored to the movable part of the access and adapted to interact with said switching means at the opening/closing of the access for opening/closing one or more circuits; - locking/releasing means (23) of said driving device (3) designed to lock it with respect to said switching device (2) to prevent unauthorized opening of the access; wherein said driving device (3) comprises at least one interaction element (17) adapted to fit into at least one slot (20) of said switching device (2) to interact with said locking/releasing means (23); wherein said locking/releasing means (23) are provided with a locking element (40) adapted to translate in said switching device (2) along a predetermined axis (A) to engage said interaction element (17) at least in a locking position wherein said interaction element (17) is locked on said switching device (2) and in a holding position in which said interaction element (17) is removable from said switching device (2); wherein said locking element (40) comprises at least one pair of mutually fastened and relatively translatable elements along said axis (A), at least one of said elements being a locking pin (24) adapted to engage said interaction element (17) at least in said blocking position; characterized in that said locking pin (24) is adapted to move at least between a first non-operative release end position in which said locking pin (24) does not lock said interaction element (17) and an operative holding position wherein an upper end of said locking pin (24) partially protrudes in a seat (25) of said interaction element (17).
  2. Switch as claimed in claim 1, characterized in that said locking/releasing means (23) are designed to move said locking pin (24) between a first non-operative release end position in which said locking element (40) does not engage said interaction element (17) and a second locking operative end position of said interaction element (17).
  3. Switch as claimed in claim 2, characterized in that said operative holding position is intermediate between said first non-operative release end position and said second locking operative end position.
  4. Switch as claimed in claim 3, characterized in that said locking element (40) comprises a pushing element (37) fastened to said locking pin (24) and provided with guide means (38, 39) suitable for guiding said locking pin (24) in said translation between said end positions and limiting its maximum stroke towards said second locking end position, said pushing element (37) being provided with an elastic contrast element (36) adapted to exert on said locking pin (24) a thrust force adapted to push it towards said holding position.
  5. Switch as claimed in any preceding claim, characterized in that said locking element (40) comprises an auxiliary retaining pin (33) fastened to said locking pin (24) in a relatively translatable manner, said auxiliary retaining pin (33) being movable in said switching device (2) and designed to be inserted into said seat (25) of said interaction element (17) to engage it when said locking pin (24) is in said first end position.
  6. Switch as claimed in claim 5, characterized in that said auxiliary retaining pin (33) is movable in said switching device (2) along a direction parallel to said axis (A).
  7. Switch as claimed in claim 5 or 6, characterized in that said auxiliary retaining pin (33) is movable in said switching device (2) with independent movement with respect to said release pin (24) to interact with said locking element interaction (17) only when said release pin (24) is in said first end position, said auxiliary retaining pin (33) being also associated in its lower end with an elastic contrast element (34) adapted to exert on said auxiliary retaining pin (33) a thrust towards said seat (25) of said interaction element (17).
  8. Switch as claimed in any claim 5 to 7, characterized in that said auxiliary retaining pin (33) is placed inside said locking pin (24), coaxially therewith.
  9. Switch as claimed in any preceding claim, characterized in that said locking/releasing means (23) comprise at least one auxiliary release control associated with at least one of the front faces (10-12) of said switching device (2) adapted to remain visible in use.
  10. Switch as claimed in claim 9, characterized in that said switching device (2) comprises a casing (4) having at least three front faces (10-12) each provided with a respective slot (20), said locking/releasing means (23) comprising at least one auxiliary release command associated with each of said front faces (10-12).
  11. Switch as claimed in any preceding claim, characterized in that said driving device (3) comprises an anchoring body (14) to the movable part of the access and an actuator (17) defining said interaction element and adapted to be inserted into said at least one slot (20) of said switching device (2), said actuator (17) having a first end (18) fastened to said anchoring body (14) and a second end (19) projecting transversely from said anchoring body (14) and housing at least one first remote communication element (21) of the transmitting or receiving type adapted to interact remotely with said switching means by sending or receiving a signal of presence.
  12. Switch as claimed in claim 11, characterized in that said switching device (2) houses thereinside at least one second remote communication element (22) of the receiving or transmitting type adapted to communicate with said first remote communication element (21) through the exchange of said presence signal, said switching device (2) being also provided with at least one slot (20) suitable to allow the insertion of said actuator (17) thereinside and the approach of said first element of remote communication (21) with respect to said second remote communication element (22).

Description

Technical Field The present invention finds application in the field of electrical devices for industrial use and in particular its object is a safety switch designed to guard an access to a safety perimeter or barrier of an industrial machine or plant. State of the art As known, the switches designed to guard the access to machines or industrial plants, such as protection panels, barriers, safety fences, comprise a switching device designed to be anchored to the fixed part of the access and a driving device designed to be anchored to the movable part. In a known way, when the movable part is closed, the interaction between the switching device and the driving device is operated, making it possible to start the machine or plant, unless there are conditions that require the specific intervention of an operator. By contrast, the opening of the access or the request for its opening, with consequent removal of the driving device from the switching device, causes the machine or plant to stop to allow the access thereto in a safe condition. The switching device is also provided with electronic control means adapted to verify that all the safety conditions are fulfilled and to stop the machine or plant in case one or more of the safety conditions are not respected. In addition, the switch may also be connected to further service circuits of the machine or plant to send reports based on the actual conditions. In order to facilitate the operators in the immediate verification of the system status, the switch may be provided with one or more signal lights, generally of the LED type, which light up according to the various system states and/or to signal the status of the different circuits connected to the switch. Usually, the signal lights are arranged on a front face of the housing of the fixed switching device and are defined by small indicator lights which turn ON/OFF according to the state of the controlled circuit, possibly also being adapted to assume different colors. Examples of these solutions are disclosed in US2019178014 or also in EP3078048, this latter in the name of the same Applicant. A first drawback of this solution lies in the fact that the use of small indicator lights as signal lights, as well as their front positioning, does not always make the reading of the lights and the interpretation of their meaning immediate and unmistakable, requiring the positioning of the operator near the switch and in such a position as to have the eyes precisely in correspondence with the lights themselves. Other solutions, such as those disclosed in US2016064163 and US4990730, show pushbutton safety switches wherein a button is made fully illuminated to indicate the status of the system. However, these solutions are also limited in the number and type of information that can be provided to the operator, as the lighting of the button will have the sole purpose of indicating the activation or deactivation status. According to a further aspect, the above cited safety switches may also be provided with locking means of the driving device designed to prevent access from being opened without prior authorization. The locking action is generally obtained by effect of the interaction between a locking mechanism inside the switching device and a corresponding element of the driving device adapted to be inserted inside the switching device to be engaged by a locking pin of the locking mechanism. This last element may be, for example, a special holding element, having a possible centering function, or the same actuator of the driving device in the case of electromechanically operated switches. Typically, the locking pin and the holding element or the actuator of the driving device are shaped so that the locking pin, in the locking position, fits with one of its ends into a suitable seat of the element of the driving device, so as to prevent its extraction. On the other hand, when the locking pin is in the unlocked position, it will not engage the element of the driving device, making it possible to extract it and consequently open the access. EP3657063 disclose a safety switch for doors wherein the locking pin is provided with a controllable internal mechanism adapted to intervene when the locking pin is in the locking position to lock it in this operating position. In particular, this solution describes a locking pin with a particularly complex structure which operates exclusively on two positions, i.e. a raised locking position and a lowered release position, without any relative movement of a portion of the pin which directly interacts with the actuator. This solution, as well as the other solutions described above, do not provide for the possibility of applying a holding force to the holding element or actuator of the driving device even in the disengaged lock pin condition. This circumstance entails the drawback that, when the locking pin is in the unlocked position but it is not yet necessary to open the access, the latte