Patent Application
20240355560
The present invention finds application in the field of electrical devices for industrial use, in particular for the control of industrial machines and plants, and particularly has as its object a safety switch designed, for example, for guarding accesses to safety perimeters or to dangerous areas of industrial machines or plants.
The invention also relates with a safety assembly for the protection of accesses which comprises the above safety switch and an actuating device suitable to cooperate therewith upon the opening/closing of the access and its locking/unlocking.
A further object of the invention is a method for assembling the above safety switch.
As known, safety assemblies for the control of industrial machines and plants generally comprise a first device operating ad a safety switch for switching the power and/or service circuits of the machine or plant, or parts thereof, and adapted to cooperate with an actuator device with driving function and which interacts with the first device to generate a command for switching the above circuits.
For safety assemblies designed to monitor the access to safety perimeters or working areas of industrial machines or plants, the switching device is usually applied to a fixed part of the protection close to the access.
The actuator device is instead generally applied directly to the movable part of the access, so that the interaction with the switching device takes place when the access is closed, according to operating schemes that can vary according to multiple schemes.
A particular kind of these assemblies is represented by assemblies provided with electronically operated switches, wherein the safety switch is provided with a first communication element, usually an antenna, suitable to communicate with a second communication element, such as a transponder, associated with the movable element, for example the actuator device or an element of the machine to be detected, to receive a coded presence signal suitable for indicating the proximity of the movable element.
Generally speaking, safety switches comprise a main module provided with a case housing thereinside both the mechanical or electronic switching elements, with the relative connection terminals for the connection of the circuits to be controlled, and, for safety switches for access control, also a mechanism for locking the actuator device, i.e. a mechanism suitable for engaging the actuator device to prevent the unsafe opening of the access.
The safety switch is then completed by one or more functional modules, among which there is generally a head designed to allow interaction between the actuator device and its locking mechanism.
In the case of electronically operated switches, the head may also house the antenna or other suitable remote communication element.
Some safety switches have a relatively complex configuration, with the head constituting a module distinct from the case and separable therefrom, generally also with the possibility of being oriented according to multiple mutually rotated positions.
These solutions require that both the case of the main module and the head have adequate mechanical resistance; to this end, various known solutions require these components to be made of metal.
DE102021105328 describes a safety switch having a main module provided with the case and an upper head suitable for being fixed from above on the main module by means of a shaped protrusion which snugly fits in a recess present on the top face of the case.
Additionally, in such configurations there are usually connecting screws to secure the head to the case. The connecting screws pass through the head along the longitudinal development direction of the switch and are screwed to the case. Portions of the case dedicated only to receiving and coupling with the connection screws are required, consequently increasing the overall size of the safety switch.
In safety switches with a simpler configuration, the head can be monolithic with the main module, so as to create a compact element.
Fixing the device to the protection is usually carried out using screws or fixing pins inserted into special holes made directly in the case of the main module.
As a consequence, to guarantee sufficient resistance against the mechanical forces transmitted by the connecting members to the case, the latter must have adequate resistance and, therefore, is generally made of metal or high-resistance polymeric material, with a consequent increase in costs which may represent a limit in the use of the device.
Furthermore, the need to insert the fixing screws into the case, also considering the presence of the locking mechanism, entails the need to increase the overall size of the device, both longitudinally and transversally, with related complications in its fixing as it will be necessary to have a fixing structure of adequate dimensions.
This condition is particularly problematic in those industrial machines wherein a too bulky safety switch could interfere with the correct closing of the access, making the machine potentially dangerous for the operator.
The object of the present invention is to overcome the above-mentioned drawbacks by creating a safety switch for guarding access to industrial machines or plants which has features of high efficiency and relative cost-effectiveness.
A particular object is to provide a safety switch for guarding accesses to industrial machines or plants which has a relatively compact configuration but which at the same time guarantees adequate safety standards.
Yet another particular object is to provide a safety switch for guarding accesses to industrial machines or plants which has relatively small size, always guaranteeing adequate stability in its fixing.
A further object is to provide a safety switch for guarding accesses to industrial machines or plants which is economical and has relatively small dimensions, always guaranteeing high resistance to the efforts to which it is subjected during its use.
These objects, as well as others which will become more apparent hereinafter, are achieved by a safety switch for guarding accesses to industrial machines or plants which, according to claim 1, comprises a case housing switching means suitable for being connected to control means for controlling the machine or plant for the opening and/or closing thereof upon the interaction with the actuating device, a locking/unlocking mechanism of the actuator housed in said case and provided with a locking/unlocking pin movable along a longitudinal direction to protrude at least partially with one end thereof from said case, a head fastened to said case and adapted to allow the interaction of said locking/unlocking pin with the actuating device and wherein said head and said case comprise respective means for mutual coupling suitable to allow stable fixing by reciprocal sliding along at least one sliding direction transverse to said longitudinal direction, preferably orthogonal to said longitudinal direction.
Fixing by sliding the head to the case will make it possible to apply simpler solutions for anchoring the entire switch to the supporting structure and which will allow for relatively small overall dimensions and/or the use of less resistant and therefore more economical materials for those parts of the switch not designed to withstand high forces.
As matter of fact, the peculiar sliding coupling will allow the head to be fixed to the case, even if not necessarily in a completely stable manner, without having to provide for the use of additional fixing means such as the classic through screws that are inserted into corresponding holes that extend longitudinally both along the head and along the case.
It should be noted that here and below the expression sliding coupling between head and housing also comprises configurations wherein only a part of the head is slidably coupled with the case.
In particular, the head may comprise a retaining body integral with said case and a removable portion which can be coupled by transversal sliding with said retaining body.
The retaining body may be shaped to define a constraint for said removable portion with said case at least along said longitudinal direction and possibly also along said transversal sliding direction. Furthermore, the retaining body may be monolithic with said case and both it and the case may be made of plastic material, with only the removable portion of said head which will be made of metallic material, so as to create a lighter and more economical switch but without reducing its overall resistance.
However, it is understood that the head may also be entirely made of metallic material or entirely made of plastic material, including the removable portion, or the removable portion may be made of plastic material with high mechanical performance.
In fact, the switch may advantageously be provided with stable anchoring means to a fixed or movable part of the access associated exclusively with the removable portion of said head.
In this way, it will also be possible to reduce the dimensions of the case, as it will not be necessary to have an increased width for the case usually necessary in similar switches according to the state of the art to provide both the holes for anchoring the switch to the frame and the above holes for fixing the head to the case.
According to a further advantageous aspect of the invention, a safety assembly is provided for guarding an access to industrial machines or plants which, in accordance with claim 16, comprises a safety switch according to the invention and an actuating device suitable to interact with said safety switch upon the closing/opening of the access for the opening/closing of one or more of the power and/or service circuits of the machine or plant.
According to yet a further advantageous aspect of the invention, a method is provided for assembling the above safety switch which, according to claim 18, provides for a coupling step between said case and said head by means of sliding of said head with respect to said case along said sliding direction, so as to guarantee rapid pre-assembly of the two main parts of the switch and which will allow the fixing of the switch in a stable configuration through the use of the front anchoring means associated with the head.
Advantageous embodiments of the invention are obtained in accordance with the dependent claims.
Further features and advantages of the invention will become more apparent in light of the detailed description of preferred but not exclusive embodiments of the safety switch and of an assembly comprising such a switch, shown by way of non-limiting example with the aid of the attached drawing tables wherein:
In particular, the switch as shown is designed to be fixed to a fixed or movable part of a perimeter, panel or safety barrier close to an access to a working area of an industrial machine or plant, to guarding this access.
In a known manner, the safety switch 1 is designed to be mounted close to the access to be monitored to interact with an actuating device.
For example, the safety switch 1 may be fixed to the fixed part of an access, such as the frame of a door, while the actuating device 2 may be fixed to the movable part of the access, or vice versa.
As visible in
The switching means, not shown as known per se, may comprise one or more pairs of mutually movable contacts, or relays, including safety relays, suitable for opening and closing respective circuits following the reception of specific commands and/or signals, according to known schemes not described here as they do not limit the present invention.
Alternatively, or in addition, the switching means may be of the electronic type, in particular of the OSSD (Output Signal Switching Device) type and comprise semiconductor devices or one or more transistors, to be connected to the above safety modules or PLCs.
Furthermore, alternatively or in combination with the OSSD outputs, safe or non-safe communication systems via BUS or radio frequency or any other known communication system may be present.
The case 4 also houses a locking/unlocking mechanism 5, described in more detail below but whose configuration is not to be understood as limiting the present invention, whose main task will be to lock the actuating device 2 to the safety switch 1.
In particular, the locking/unlocking mechanism 5 is provided with a locking/unlocking pin 6 movable in the case 4 along a longitudinal direction X to protrude at least partially with an upper end 7 thereof outside to the case 4, as shown in
The safety switch 1 is also provided with a head 9 fixed above the case 4 and which is designed to allow the interaction of the locking/unlocking pin 6 with the actuating device 2.
In particular, the head 9 may be provided with one or more slots 10 suitable to allow the interaction of the locking/unlocking pin 6 with an actuating pin 11 protruding from the actuating device 2.
In particular, the slots 10 will allow the actuating pin 11 to enter at least partially into the head 9 to be locked with respect to the safety switch 1 following the retention action of the locking/unlocking pin 6.
The actuating pin 11 may have retention and centering function or even an actuator function, depending on the type of actuator device.
However, it will also be possible to provide solutions wherein the head 9 has no slots or similar elements, if the actuating device 2 is not provided with an actuating pin or other mechanical or electromechanical actuator, as for example in some solutions of switches with totally electronic operation like the one disclosed in WO2015/155744 in the name of the same Applicant.
In these cases, the safety switch 1 may also be devoid of the locking/unlocking mechanism 5.
Optionally, the safety switch 1 may be implemented with further auxiliary modules, such as, for example, modules equipped with emergency controls, manual release, connection modules, even of different types to allow the connection with different types of cable, or other types of modules according to configurations all typical for this kind of product.
These auxiliary modules may be fixed and integrated with the case 4 or they may be anchored thereto in a removable and/or orientable manner.
The head 9 and the case 4 are mutually coupled by respective mutual coupling means suitable to allow their mutual stable fixing by mutual sliding along at least one sliding direction Y transverse to the longitudinal direction X.
Generally speaking, the mutual coupling means will comprise a first coupling element 12 integral with the case 4 and a second coupling element 13 integral with the head 9, with the two coupling elements 12, 13 both comprising mutually counter-shaped coupling portions to allow their coupling by sliding along the sliding direction Y.
In the exemplary embodiment of
Preferably the sliding direction Y will be orthogonal to the longitudinal direction X, as schematized in
Even more preferably, the sliding direction Y corresponds with a direction of insertion, in use, of the actuating pin 11 inside the head 9 and through one of the slots 10.
In the preferred configuration of the figures, as can be seen more clearly from
The head 9 will instead be provided with a removable portion 13 defining the second coupling element and which will be adapted to be coupled to the retaining body 12 by transversal sliding along the sliding direction Y.
The retaining body 12 will be suitably shaped to define a constraint for the removable portion 13 of the head 9 with respect to the case 4 at least along the longitudinal direction X, in both senses along the same.
In other words, the retaining body 12 limits, or more preferably blocks, the mutual sliding between head 9 and case 4 along the longitudinal direction X in both senses.
Even more preferably, the retaining body 12 will be suitably shaped to define a constraint for the head 9 with respect to the case 4 also along the sliding direction Y, limiting, or more preferably blocking, the mutual sliding between the head 9 and the case 4 along the sliding direction Y, in at least one sense.
Even more preferably, the retaining body 12 will be suitably shaped to define a constraint for the head 9 with respect to the case 4 also along a direction perpendicular to the longitudinal direction X and to the sliding direction Y.
In the preferred embodiments, the retaining body 12 will be suitably L-shaped, i.e. with a longitudinal arm 14 extending from the upper face 15 of the case 4, i.e. the one provided with the upper passage 8 for the locking/unlocking pin 6, and a transverse arm 16 cantilevered from the upper end of the longitudinal arm 14. Optionally, the transverse arm 16 comprises a cover cap 41.
In the preferred embodiments, the transverse arm 16 extends, with respect to the longitudinal direction X, close to the level of the upper end 40 of the removable portion 13. In particular the transverse arm 16 covers, completely or partially, or is coplanar with the upper end 40 of the removable portion 13. In this way the removable portion 13 is predominantly interposed between the upper face 15 of the case 4 and the transverse arm 16 which, therefore, prevent the movement of the removable portion 13 along the longitudinal direction X.
In turn, the removable portion 13 of the head 9 will be shaped to surround the retaining body 12 on at least three sides and define with it a head 9 with a substantially prismatic shape, for example approximately in the shape of a cube or parallelepiped as in the figures.
In particular, the removable portion 13 will have a front face 17 and a pair of side faces 18, 19, on at least one, preferably at least two, of which a slot 10 will be made for the insertion of the actuating pin 11.
For example, in the embodiment shown in
The retaining body 12 and the removable portion 13 comprise respective coupling portions with mating shape designed to define a shape coupling therebetween.
In this example, the transverse arm 16 will be provided of transversal sliding guides 20 adapted for sliding engage respective transversal sliding counter-guides 21 made on each of the two side faces 18, 19.
It is understood that the sliding coupling between the removable portion 13 and the retaining body 12 may also be obtained with different coupling systems, for example with joints or other couplings of the male and female type, without particular limitations.
The head 9 will also be shaped to allow the insertion and consequent longitudinal movement therewithin of the protruding end 7 of the locking/unlocking pin 6, so as to allow its interaction with the actuating pin 11.
According to a further particularly advantageous aspect, in a preferred but not exclusive embodiment, the retaining body 12 will be monolithic with the case 4 and possibly made of one piece therewith and in the same material.
By way of example, the retaining body 12 will be monolithic with the case 4, for example by means of a single mechanical processing operation, such as moulding.
Optionally, it will be possible to manufacture the case 4 and the retention body 12 in plastic material, while the removable portion 13 of the head 9 may be made in metallic material or even in plastic material with high mechanical performance to guarantee adequate resistance to interactions with the actuating device 2 and to efficiently withstand the stresses transmitted both by the actuating device 2 and by the constraint produced by the anchoring means to the fixed frame of the protection or to another fixed or movable part of the access.
This shape makes the safety switch 1 light and economical but at the same time resistant.
In particular, the above stable anchoring means of the safety switch 1 may be associated exclusively with the head 9, and even more preferably only with the removable portion 13.
As more clearly visible from the front view of
Preferably, the through anchoring holes 22 will extend along a direction parallel to the sliding direction Y or orthogonal thereto and also to the longitudinal direction X.
The anchoring through holes 22 will be made in at least one between the front face 17 and the side faces 18, 19 of the removable portion 13 of the head 9, for example on the front face 17 as in the figures, and laterally to the longitudinal arm 14.
Optionally, the anchoring through holes 22 may be closed by respective anti-tampering caps, i.e. plugs configured to break once removed to give evidence of a possible tampering or other intervention on the anchoring members present inside the anchoring through holes 22.
As visible from
This particular embodiment of the anchoring means will also allow the head 9 to be stably locked with respect to the case 4 at the same time as the entire safety switch 1 is fixed to the access, without resorting to further fixing means between the head 9 and the case 4.
In these cases, the coupling between the head 9 and the case 4 may be of a completely removable type, obviously in the event that the safety switch 1 is not fixed in position by the anchoring means. Alternatively, the mutual coupling means may comprise constraint elements suitable for making the coupling between head 9 and case 4 completely blocked or only partially modifiable.
For example, the constraint elements can only partially block the coupling between head 9 and case 4 to make the head 9 orientable with respect to the case 4 but still constraining the former with respect to the latter along the transversal sliding direction Y.
Preferably, the constraint elements may be adapted to completely block the movement of the head 9 with respect of the case 4 or to limit it to a predetermined maximum stroke, avoiding complete detachment.
This configuration will have the purpose of preventing the user from dismantling the safety switch 1.
In a preferred configuration, visible in
According to a first variant, the safety switch 1 may be of the electronically operated type and it will be designed to communicate with the actuating device 2 by exchanging an electronic presence signal, preferably of the coded type.
Generally, the receiving element will be an RFID (Radio Frequency Identification) type antenna or reader designed to communicate with the transmitting element, which may instead be a transponder, when the latter is at the minimum detectable distance from the antenna or reader.
In the example of
In particular, the RFID type receiving element will emit a signal capable of exciting the transponder, which is in turn equipped with an RFID tag with identification code, which in turn will emit a response signal which will be received by the receiving element and which has to be recognized by the control means of the safety assembly, appropriately equipped with a CPU, in order to allow the machine or plant to be started.
Code recognition can be unique or generic, depending on whether you want to create a safety switch with a high or low coding level in accordance with the EN ISO 14119 standard.
Advantageously, the transponder will be coded so that it can be uniquely recognized by the receiving element, preventing the use of actuating devices other than the one connected to the access, avoiding the risk of unsafe opening of the access.
From the same section it is also possible to observe a possible configuration of the locking/unlocking mechanism 5, provided with an electromagnet 28 capable of being energized/deactivated to promote the longitudinal translation, in one or the other sense, of a pusher 29 mechanically connected to the locking/unlocking pin 6.
Consequently, the locking/unlocking pin 6 will move along the longitudinal direction X, according to methods known in the field and therefore not disclosed in larger detail.
Briefly, following the energization or de-energization of the electromagnet 28, the locking/unlocking pin 6 may translate in a first sense along the longitudinal direction X so that its upper end 7 fits into the seat 30 provided in the head 9 and designed to accommodate the actuating pin 11, blocking the latter with respect to the head 9.
Alternatively, the locking/unlocking pin 6 may translate in the opposite sense always along the longitudinal direction X to remove the upper end 7 from the seat 30, so as to allow the extraction of the actuating pin 11 and the unlocking of the access.
The electromagnet 28 may be replaced in a completely equivalent manner by another electromechanical, electric, hydraulic or pneumatic actuator means housed in the case 4.
The first communication element 26 may advantageously be housed inside the transversal arm 16 of the retaining body 12, to face the protruding upper end 7 of the locking/unlocking pin 6 and detecting the presence of the second communication element 27, if inserted into the seat 30 of the head 9.
Conveniently, the second communication element 27 will be inserted into the actuating pin 11 which enters into the seat 30 of the head 9.
However, it is understood that the transmitting element may also be of another type, such as an actuator operating using magnetic or electromagnetic, optical, mechanical, induction, pressure or other types of sensors and consequently the receiving element will adapt to the nature of the transmitting element.
According to a variant not illustrated, the safety switch may be of the electromechanically operated type for interacting with an actuation device equipped with a key actuator in place of the retention and centering pin, according to known methods described for example in EP0871188.
The electrically or electromechanically operated safety switch 1 will also be provided with a PCB (Printed Circuit Board) 31 housed in the case 4 and on which there will be both a control and communication unit and the switching means.
By way of example, the control unit may comprise one or more safety CPUs (Central Processing Units) which communicate with each other in a redundant manner and which will both communicate with the first communication element 26.
Furthermore, the locking/unlocking mechanism 5 may be equipped with sensors suitable of detecting the locked position of the locking/unlocking pin 6 and which communicate with the control unit.
By way of example, the control unit is designed to control the switching means based on the signals transmitted by the first communication element 26 and by the sensors of the locking/unlocking mechanism 5.
Optionally, PCB 31 may also comprise electrical and electronic circuits for communication of the control unit and of the switching means with external command and control systems, such as for example communication BUS of the safe type (Profisafe, IOlink safety, CIP Safety and similar) and non-safe type (Profinet, IOlink, EtherNet/IP, Profinet and similar) and for the management of the various components, including any LED lights or other signaling elements.
According to a further particularly advantageous aspect, PCB 31 will extend longitudinally inside the case 4 and also in the longitudinal arm 14 of the retaining body 12, to connect directly to the first communication element 26 housed in the transverse arm 16.
This configuration will allow for a particularly compact structure, with a reduction in the overall height of the safety switch 1.
From
Finally,
The switch of the invention is suitable for use within a safety system for the control of a machine or plant and which comprises one or more safety switches associated with respective accesses to be monitored, which are not necessarily identical to each other nor all in accordance with the present invention, and suitable for interacting with respective actuating devices. The system may also comprise one or more safety modules or PLCs designed to manage the power supply of the machine or plant on the basis of the signals exchanged with safety switch 1 and allow its safe operation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102023000007557 | Apr 2023 | IT | national |
