Safety switch for access control

Abstract

A safety switch for controlling an industrial machine or facility entrance, comprising: a switching device (2) housing a switching device; and an actuator device (3) having an operating pin (8) which interacts with the switching device when opening / closing the inlet; a locking / unlocking mechanism (14) housed in the switching device (2) and provided with a locking pin (15) movable between a locked position and an unlocked position of the inlet; an operating pin (8) associated with the actuator device (3) to interact with a locking pin (15) to keep the actuator device (3) fastened to the switching device (2); the switching device (2) in turn accommodates a locking element with controlled deformation which is mechanically connected to the locking pin (15) and which is dimensioned to plastically deform when a deformation stress above a predetermined threshold is applied to the locking pin (15).

Description

Technical Field

[0001] The present invention is applied to the field of industrial electrical equipment, and in particular to a safety switch for controlling the entrance to a safety barrier or perimeter of industrial machines and facilities. Background Art

[0002] As is known, safety switches for controlling access to safety barriers and perimeters of industrial machines or facilities generally comprise a switch device adapted to be anchored to a fixed part of the access and an actuator device adapted to be anchored to a movable part.

[0003] The two devices are able to interact as the access door opens and closes, signaling open / closed conditions and locked / unlocked conditions to the control system of the machine or facility, and allowing for varying methods of controlling the machine or facility depending on the configuration employed.

[0004] The interaction between the switching device and the actuator device may be of a mechanical type or of an electromechanical type, wherein the actuator device is provided with a mechanical actuator, such as a key actuator, adapted to be inserted inside the switching device to mechanically interact with the switching device, and of a fully electronic type.

[0005] In the second case, the interaction between the two devices is carried out by exchanging presence signals by means of which it is possible to distinguish the proximity between the two devices and thus the open and closed conditions of the entrance.

[0006] In both embodiments, the actuator device may also be provided with a pin having the function of centering and holding the actuator device on the switching device, thereby preventing the entrance from being opened without prior consent from the central system or after release due to vibration or other minimum request unrelated to the opening attempt.

[0007] The pin of the actuator device is usually designed to engage with the locking pin of the locking / unlocking mechanism within the switch device.

[0008] Generally, in an electromechanical switch, the action is performed by a key or the mechanical actuator itself.

[0009] Some solutions can also detect any damage to the lock / unlock mechanism pins so that switch operation can be prevented even if such an event occurs.

[0010] However, a situation where the locking / unlocking mechanism pin is damaged should always be avoided, because in this case, an integral part of the same locking pin may still drop and thus may be falsely detected as a correct operation.

[0011] JP2002216591 and JP2004079204 disclose a switch which, in a first configuration, aims to avoid pin breakage by providing a mechanism which prevents excessive stress being applied to the pin by a traction force applied to the actuating pin, by a series of guiding mechanisms which allow the applied stress to be dispersed.

[0012] However, the structural complexity of the locking mechanism makes this solution relatively expensive and unreliable.

[0013] JP2007257973 also discloses a safety switch solution, which prevents the locking pin from being deformed or damaged even under excessive stress.

[0014] On the other hand, in the second embodiment of JP2002216591, entry always occurs even if the pin is damaged. However, this does not avoid the above-mentioned risk that the system may not detect such an opening due to the downward translation of the pin.

[0015] JP2002216591 and JP200345294 show further solutions which provide for the release of the actuator pin even if the locking pin is deformed or damaged; however, no measures are provided to prevent a drop in the event of damage or deformation of the locking pin.

[0016] JP2004079190 discloses a safety switch in which a cam mechanism is provided, which intervenes to operate a locking element, open a locking pin and cause the switch device to open, avoiding damage to the locking pin, when it is detected that the extraction force applied to the actuator is greater than a limit value.

[0017] The value of the limit force at which the cam mechanism intervenes can be set arbitrarily by means of a control element in the locking element.

[0018] Other examples of switches with locking mechanisms are described in US 2019 / 316381, US 2011 / 127147, and US 2020 / 165839. Summary of the invention

[0019] The object of the present invention is to overcome the above-mentioned drawbacks and to provide a safety switch for access control of industrial machines and facilities which is highly efficient and relatively cost-effective.

[0020] A specific object of the present invention is to provide an access control safety switch which provides evidence of excessive stress applied to the pins of the locking / unlocking mechanism exceeding a threshold value and which may cause damage to the actuator device itself and / or the locking / unlocking mechanism.

[0021] Another specific object is to provide a safety switch for access control which, even in the event of damage, prevents the pin of the locking / unlocking mechanism from moving to the unlocking position of the access.

[0022] These objects, as well as other objects which will become more apparent hereinafter, are achieved by a safety switch for entrance control, which, according to claim 1, comprises: a switching device which accommodates a switching device for controlling one or more control and / or service circuits of a machine or facility; an actuator device which is suitable for interacting with the switching device to open / close one or more of the circuits when opening / closing the entrance; a locking / unlocking mechanism which is accommodated in the switching device and is provided with a locking pin which can be moved between at least one locked position of the entrance and at least one unlocked position of the entrance; an operating pin which is associated with the actuator device and is suitable for interacting with the locking pin to keep the actuator device fastened to the switching device.

[0023] The switching device accommodates at least one locking element with controlled deformation, which is mechanically connected to the locking pin and is dimensioned to deform plastically without breaking after a first deformation stress above a predetermined threshold is applied to the locking pin by the operating pin.

[0024] In this way, if excessive stress is applied to the locking pin, the locking pin itself or a suitable locking element with controlled deformation will deform without breaking.

[0025] The locking pin will therefore remain wedged inside the switching device, without the downstream portion of the deformed end being able to drop down anyway and thus signal unlocking of the access opening.

[0026] In this case, a situation may occur where the actuator pin remains stuck and cannot be removed, thus causing an error and preventing the machine from being restarted in an unsafe condition or opening the access door while the machine is running.

[0027] Depending on the position of the controlled deformation of the locking element, the locking pin can be locked even in the lowered position or in an intermediate position.

[0028] Also in this case, a safe entrance condition within the protective perimeter will be guaranteed, because when the entrance is closed, the actuator pin cannot be locked by the locking pin, which is now stuck, thus generating an error, which will prevent the restart of the machine or facility.

[0029] Advantageous embodiments of the invention can be obtained from the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further features and advantages of the invention will become more apparent from the detailed description of a preferred but non-exclusive embodiment of the safety switch according to the invention, which is illustrated by way of non-limiting example with the aid of the accompanying drawings, in which:

[0031] Figure 1 is a perspective view of the safety switch in an operating configuration corresponding to an access port being in a closed state;

[0032] Figure 2 yes Figure 1 A cross-sectional view of the safety switch shown in an operating configuration corresponding to an entry state during closing or opening;

[0033] Figure 3 yes Figure 1 A cross-sectional view of the safety switch shown in an operating configuration corresponding to a closed and locked entry state;

[0034] Figure 4 yes Figure 1 The safety switch is shown in a cross-section in the operating state with the locking pin deformed. DETAILED DESCRIPTION

[0035] With reference to the accompanying drawings, there is shown a preferred but non-exclusive embodiment of a safety switch according to the invention, which is generally designed for controlling at least one entrance to an industrial machine or facility.

[0036] Generally speaking, the safety switch ( Figure 1 denoted as a whole by 1) is designed to be installed or in any case placed at the entrance of a guard, preferably but not exclusively, of the barrier or movable panel type, as known per se, not shown, suitable for controlling access to a security perimeter or other working area in which an operating machine or industrial installation is located, preventing unsafe passage.

[0037] In a known manner as well, the main task of the safety switch 1 is to interrupt the operation of the machine or installation immediately or at a fixed time, or of one or more selected parts of the machine or installation, when access is opened or even only when there is a request to open access.

[0038] The inlet may be of any type, such as hinged and sliding, right-hand or left-hand, without particular limitation.

[0039] In the configuration shown, the safety switch 1 is of the electronically driven type, ie a remote communication system is provided between the switch part and the drive part, as will be described more clearly below.

[0040] However, according to an alternative configuration not shown, the switch 1 can also be operated mechanically or electromechanically by a key actuator, technically equivalent or similar to what happens with the switch described above.

[0041] In its most basic form, the safety switch 1 comprises a switching device 2, typically adapted to be anchored to a fixed part of an inlet to be controlled, and an actuator device 3, typically adapted to be anchored to a movable part of the inlet.

[0042] The method of anchoring the switching device 2 and the actuator device 3 to the respective parts of the inlet is of a known type and does not form part of the present invention and will not therefore be described or illustrated in more detail.

[0043] In the preferred but non-exclusive configuration shown, the switching device 2 comprises a containing body 4, which is provided with a housing 5, inside which a switching device is housed, the switching device not visible in the figure but having a known configuration suitable for being operably connected in a known manner to one or more electrical and / or electronic circuits for the power supply and / or control of main circuits and / or service and / or emergency circuits of a machine or facility.

[0044] The switch device may be selected from commonly used devices in the art, and may also vary according to the function of the safety switch 1 without particular limitation.

[0045] The connection method of the switchgear will be selected from the typical connection methods of this type of product and will not be described in detail below.

[0046] The housing 5 may also accommodate control means, such as a microprocessor or CPU not shown, adapted to receive input signals from control and / or service circuits via corresponding communication channels (e.g. data transmission bus, transistors, electromechanical contacts, etc.) to verify correct operation.

[0047] In this way, the control device can command the switchgear so that they send an error signal and / or shut down the facility in the absence of a communication signal from one of the communication channels or when a fault is detected inside or outside the device.

[0048] The housing 5 is also associated with a head 6 designed to interact with the actuator device 3 in order to allow the actuator device 3 to interact with the switching device, according to the method described below.

[0049] The head 6 may be integral with the housing 5 or be a separate module applied to the housing 5 , possibly in a removable manner and / or orientable in two or more positions according to rotation relative to the main axis of extension of the housing 5 .

[0050] In turn, the actuator device 3 will include an anchoring body 7, which is provided with its own anchoring means for anchoring to the inlet and is associated with an operating pin 8, which has a first end 9 fixed to the anchoring body 7 and a second end 10 protruding laterally from the anchoring body 7 and which will interact with the switching device.

[0051] To this end, the head 6 will be provided with one or more grooves 11 in at least one of its front faces 12, 13 or in one of the upper and / or lower axial faces, allowing the operating pin 8 to be inserted therein and to interact therewith with the switching device.

[0052] In a preferred but non-exclusive embodiment of the figures, the head 6 will be provided with two or more grooves 11 formed on respective front faces 12, 13, so that the switching device 2 can always be anchored in the same orientation, but still allowing interaction with the actuator device 3, regardless of the latter's approach direction, which will instead depend on the type of closure of the entrance.

[0053] However, it will be appreciated that a single slot 11 associated with a fixed or rotating head 6 may also be provided.

[0054] from Figure 2-4 As can be seen more clearly in the cross section of FIG. 5 , the housing 5 also accommodates a locking / unlocking mechanism 14 of the operating pin 8 adapted to engage with the operating pin 8 to keep the second end 10 thereof locked when the operating pin 8 is fully inserted into the head 6 .

[0055] In this context, the expression "fully inserted" refers to the position of the operating pin 8 inside the head 6 such that the inlet is considered correctly closed.

[0056] Specifically, the locking / unlocking mechanism 14 is provided with a locking pin 15, which can perform translational or rotational translational movement in the accommodating body 4 along a predetermined longitudinal movement direction X, and the predetermined longitudinal movement direction X is basically parallel to the main extension direction L of the shell 5 and orthogonal to the insertion direction Y of the operating pin 8 in the head 6.

[0057] In the unlocked entrance state, whether in the entrance opening stage or in the entrance closing stage, the operating pin 8 will act on the locking end 16 (representing its upper end in the figure) of the locking pin 15 to make it translate downward, such as Figure 2 shown.

[0058] Specifically, the locking pin 15 can be moved between at least one entry unlocking position and a locking position in the housing 4, wherein in the unlocking position, the locking end 16 of the locking pin 15 is not inserted into the head 6 or is only partially inserted, and in the locking position (such as Figure 3 As shown), the locking end 16 is fully inserted into the head 6, thereby engaging with the operating pin 8 in a manner that prevents it from being pulled out.

[0059] In the unlocked position, the locking end 16 can be completely retracted so as not to interact with the operating pin 8, or, in a preferred manner, it can partially protrude into the head 6 so as to engage with the operating pin 8 in any case, exerting a minimum retaining force that is sufficient not to prevent the opening of the entrance after the operator applies a traction force, but at the same time sufficient to avoid involuntary opening due to vibrations or shocks applied to the entrance.

[0060] In the preferred but not exclusive configuration shown, the locking pin 15 will be designed to move between a raised locking position of the entrance and a lowered unlocked position, in which it engages the operating pin 8 to retain it in the head 6, and in which, when a lateral stress greater than the retaining force exerted by the locking pin 15 is applied, the operating pin 8 can be withdrawn from the head 6 and, correspondingly, opening of the switching device occurs.

[0061] Preferably, the operating pin 8 will be provided with a seat 17 for inserting the locking end 16 of the locking pin 15 , the seat 17 being arranged in axial alignment with the locking pin 15 when the operating pin 8 is fully inserted into the head 6 .

[0062] The seat 17 may be defined by a concave surface, or even by a hole with a suitable entrance diameter, or even by any other geometric shape for form coupling, formed in the lower surface of the second end 10 of the operating pin 8 to allow at least partial insertion of the upper locking end 16 of the locking pin 15, thereby preventing the entrance from being opened when the locking / unlocking mechanism 14 is in the locked configuration.

[0063] According to a first particular aspect of the invention, the switching device 2 will house a block element with controlled deformation, dimensioned to deform plastically when a first deformation stress above a predetermined threshold is exerted on the locking pin 15 by the operating pin 8 .

[0064] In a first embodiment, the locking element with controlled deformation will be dimensioned to deform plastically without breaking.

[0065] According to another variant, the locking element with controlled deformation is dimensioned so as to deform plastically but also to allow partial fracture, ie such fracture does not in any case lead to the detachment of any part thereof.

[0066] The locking element with controlled deformation will be mechanically connected to the locking pin 15 , for example by a more or less complex kinematic chain, which will allow the stresses acting on the locking pin 15 to be transferred to the locking element, or it can be part of the locking pin 15 .

[0067] Possibly, there may also be a plurality of locking elements with controlled deformation, which are adapted to deform upon exertion of corresponding deformation stresses on the locking pin 15, the values ​​of which are not necessarily equal to one another.

[0068] For example, according to Figure 4 The portion of the locking pin 15 adapted to be deformed in a controlled manner may be the locking end 16 thereof.

[0069] The locking pin 15 will comprise a body 18 extending along a main axis of development A parallel to its direction of movement X and connected to the locking end 16 by a controlled deformation or weakening zone 19 .

[0070] Furthermore, the switch device 2 will comprise a longitudinal passage 20 in which the body 18 of the locking pin 15 will be slidably received in an axially aligned position.

[0071] The weakened area 19 can be defined, for example, by a portion of the locking pin 15 having a reduced cross-section, such as having a reduced cross-section relative to the cross-section of the body 18, so as to define a narrow portion, thereby allowing the locking end 16 to move from an undeformed position when a deforming stress is applied.

[0072] Alternatively, the weakened area 19 may be obtained by making one or more notches or other local structural weakenings on the locking pin 15, also corresponding to the several deformations.

[0073] The locking end 16 of the locking pin 15 is preferably substantially cylindrical or disc-shaped, possibly with a beveled chamfered edge, in order to interact with the second end 10 of the operating pin 8 during the insertion and extraction phases.

[0074] The transverse dimension of the locking end 16 does not necessarily correspond to the transverse dimension of the main body 18 .

[0075] In addition, the locking end 16 of the locking pin 15 is sized so that when a first deforming stress is applied, it transitions from an undeformed state axially aligned with the longitudinal channel to a deformed and misaligned position relative to the axis A of the longitudinal channel 20, thereby causing the locking end 16 to at least partially interfere with the inner surface of the longitudinal channel 20.

[0076] Interference means that there is contact between the deformed portion of the locking pin 15 and the inner surface of the longitudinal channel 20 that prevents mutual sliding.

[0077] Thus, as the locking end 16 deforms, the locking pin 15 will not move toward the unlocked position because it will remain wedged in the longitudinal channel 20 .

[0078] According to one possible but not exclusive embodiment, there will be a gap of a few tenths of a millimeter around the locking end 16 between the outer side surface of the locking end 16 and the inner surface of the longitudinal channel 20, so that the longitudinal channel 20 also serves as a guide for the sliding of the locking pin 15.

[0079] A sensor device will be appropriately provided inside the switch device 2 for detecting the position of the locking pin 15 .

[0080] The present invention is not limited to the type of sensor device employed, as any shape, technology or type of sensor may be used.

[0081] By way of example, these sensor means may comprise one or more photocells or other sensors of optical type suitable for detecting the beginning of travel and possibly also the reaching of an end of travel or an intermediate position of the locking pin 15 and / or of the body 18 .

[0082] As an alternative to optical type devices, different types of sensors may be used, such as magnetic sensors or the like, for example magnetic sensors, RFID, electrical sensors or sensors according to any other technology.

[0083] The sensor means would be designed to detect movement of the locking pin 15 and / or body 18 following the door open signal and send an error signal if they do not detect the correct downward travel, which could be associated with an error condition causing the facility to stop.

[0084] In this design, the actuating pin 8 has, in addition to its function as a holding and centering element relative to the switching device 2 , also the function of an actuator.

[0085] In particular, the operating pin 8 will be equipped with a first remote communication element of the sending or receiving type (not shown since it is known per se), suitable for communicating with a second communication element of the receiving or sending type (also not shown) present in the switching device 2 by sending or receiving a presence signal.

[0086] For example, a first communication element could be placed at the periphery of seat 17 , possibly incorporated into second end 10 of operating pin 8 , while a second communication element would be arranged inside head 6 so as to communicate with the first communication element when operating pin 8 is fully inserted into head 6 .

[0087] Alternatively, the first telecommunication element may be inserted into the anchor 7, while the second telecommunication element is located in the head 6 or housing 5, with the respective positions at least partially facing each other in the closed access condition.

[0088] According to an alternative variant, the first telecommunication element may be of receiving type, for receiving a presence signal sent by the second telecommunication element, the second telecommunication element would then be of transmitting type.

[0089] The receiving element may be an RFID (Radio Frequency Identification) type antenna configured to receive remote control signals transmitted by the transmitting element, which may also be a transponder when the transmitting element is at a minimum detectable distance from the antenna.

[0090] In particular, the transponder can be equipped with an RFID tag with an identification code which is to be received by the receiving element and must be recognized by the control device of the safety component appropriately equipped with the CPU in order to allow the start-up of the machine or the installation.

[0091] The identification code may be unique or universal, depending on whether you are creating a high-level or low-level coded switch.

[0092] Advantageously, the RFID tag will be coded so that it can be unambiguously identified by the receiving element and prevent the use of actuator devices other than the one connected to the portal, thereby avoiding the risk of unsafe opening of the portal.

[0093] Recognition of the tag by the antenna will allow activation of the locking / unlocking mechanism 14 .

[0094] For example, the electromagnet 22 or other electromechanical, electric, hydraulic or pneumatic type actuator device located in the housing 5 can be energized or deactivated depending on the type of operation to push the locking pin 15 to translate upward or downward in accordance with methods known in the art (and therefore not described in detail), so that the locking pin 15 enters the seat 17 of the operating pin 8, locking it in the head 6, or pushes it to translate downward to unlock the entrance.

[0095] However, it should be understood that the transmitting element can also be of other types, such as an element with electromechanical action, such as a key actuator, or operated by a magnetic or electromagnetic, optical, mechanical, inductive, pressure or other type of sensor, and the receiving element will therefore be adapted to the properties of the transmitting element.

Claims

1. A safety switch for controlling the entrance to an industrial machine or facility, comprising: - a switchgear (2) containing switchgear for controlling one or more command and / or service circuits of a machine or installation; - actuator means (3) adapted to interact with said switching device to open / close one or more of said circuits when opening / closing an inlet; - a locking / unlocking mechanism (14) housed in the switching device (2) and provided with a locking pin (15) movable in the switching device (2) between at least one locking position of the entry and at least one unlocking position of the entry; - an operating pin (8) associated with the actuator device (3) and adapted to interact with the locking pin (15) to keep the actuator device (3) fixed to the switching device (2); Characterized in that the switching device accommodates at least one locking element with controlled deformation, which is mechanically connected to the locking pin (15) and whose dimensions are designed to undergo plastic deformation when the operating pin (8) exerts a first deformation stress on the locking pin (15) that is higher than a predetermined threshold.

2. The safety switch according to claim 1, characterized in that: The locking element with controlled deformation is part of the locking pin (15).

3. The safety switch according to claim 2, characterized in that: The locking pin (15) comprises a locking end (16) adapted to engage the operating pin (8) and define the locking element with controlled deformation.

4. The safety switch according to claim 3, characterized in that: The locking pin (15) is movable in the switching device (2) along a predetermined longitudinal movement direction (X) and comprises a body (18) extending along a main extension axis (A) substantially parallel to the movement direction (X) and connected to the locking end (16) via a weakened area (19).

5. The safety switch according to claim 4, characterized in that: The weakened area (19) is defined by a portion of the locking pin (15) having a smaller cross-section than the cross-section of the body (18).

6. The safety switch according to claim 4 or 5, characterized in that: The weakened area (19) is defined by one or more areas of reduced cross-section and / or grooves of the locking end (16) of the locking pin (15).

7. The safety switch according to any one of claims 4 to 6, characterized in that: The switch device (2) has a longitudinal passage (20), wherein the body (18) of the locking pin (15) is slidably received in the longitudinal passage (20) in an axially aligned position.

8. The safety switch according to claim 7, characterized in that: The locking end (16) of the locking pin (15) is generally cylindrical or disc-shaped and is sized to move from an undeformed state axially aligned with the longitudinal channel (20) to a deformed and misaligned position relative to the axis (A) of the longitudinal channel (20) when the first deforming stress is applied, and so that the locking end (16) at least partially interferes with the inner surface of the longitudinal channel (20).

9. Safety switch according to any one of the preceding claims, characterized in that The switch device (2) contains a sensor device inside for detecting the position of the locking pin (15) and detecting the movement of the locking pin (15) when sending a locking or unlocking signal of the entrance, so as to send an error signal when the correct travel towards the corresponding locking and unlocking positions of the entrance is not detected.

10. The safety switch according to any one of the preceding claims, characterized in that The locking element has a controlled-deformation locking pin (15) dimensioned to deform in such a way as to prevent the operating pin (8) from being pulled out of the switching device (2).

11. The safety switch according to any one of the preceding claims, characterized in that The actuator device (3) comprises an anchor body (7) for anchoring to the inlet, and the operating pin (8) extends from the anchor body in a transverse direction (Y).

12. The safety switch according to any one of claims 3 to 11, characterized in that: The switch device (4) comprises a housing (5) for accommodating the switch device and a head (6), wherein the head (6) is provided with at least one slot (11) for inserting the operating pin (8), and the size of the locking pin (15) enables the locking end (16) to move between the locking position and the unlocking position, in which the locking end (16) is completely inserted into the head (6), and in the unlocking position, the locking end (16) is not inserted into the head (6) or is only partially inserted.

13. Safety switch according to any one of the preceding claims, characterised in that The actuator device (3) is equipped with a first telecommunication element of the receiving or transmitting type, and wherein the switch device (2) is equipped with a second telecommunication element of the transmitting or receiving type suitable for communicating with the first telecommunication element by sending or receiving a presence signal.

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