Safety device

Abstract

Safety device (1) comprising a safety switch (2) having an RFID unit and an actuator (3) movable relative to the safety switch (2) with a transponder (7), wherein in a closed position of the actuator (3) data is read from the transponder (7) by means of the RFID unit and the safety switch (2) generates an output signal depending on this, and wherein the safety switch (2) has a magnetic locking device by means of which locking of the actuator (3) in its closed position can be effected, characterized in that the locking device has an electromagnet having a pole surface (10), wherein a read head (8) of the RFID unit is arranged in the center of the pole surface (10), and that a read coil (19) of the RFID unit is magnetically insulated from the electromagnet.

Description

[0001] The invention relates to a safety device.

[0002] Such safety devices are used in the field of safety engineering, particularly in the area of ​​machine safety.

[0003] A typical monitoring function of a safety device consists of monitoring a separating protective device, such as a safety door, through which access to a danger area on a machine or system is enabled.

[0004] Known safety devices feature safety switches.

[0005] The operation of a hazardous system within the danger zone is only authorized by a safety controller if the safety switch detects that the separating protective device is in its closed position. For this purpose, the safety switch can include an RFID unit that detects a transponder located in an actuator on the separating protective device. The functionality of the safety switch can be extended by a locking mechanism that interlocks the separating protective device in its closed position. The locking mechanism engages by retracting a locking element, in particular a locking bolt, into a locked position. An actuator in the form of an electric or electromagnetic drive is provided to retract the locking element into the locked position.

[0006] From EP 4 321 790 A1, a safety device with a safety switch is known, which has a magnetic holding device. The actuator associated with the safety switch is held in its closed position by the magnetic force of an electromagnet. A reading coil, which is part of an RFID unit, is arranged laterally offset from the electromagnet.

[0007] The invention is based on the objective of providing a safety device which has a high level of functionality despite its compact and cost-effective design.

[0008] The features of claim 1 are provided to solve this problem. Advantageous embodiments and expedient further developments of the invention are described in the dependent claims.

[0009] The invention relates to a safety device comprising a safety switch with an RFID unit and an actuator movable relative to the safety switch, containing a transponder. When the actuator is in a closed position, data is read from the transponder by means of the RFID unit. Depending on this, the safety switch generates an output signal, and the safety switch has a magnetic locking device by means of which the actuator can be locked in its closed position. The locking device has an electromagnet with a pole face, wherein a read head of the RFID unit is arranged in the center of the pole face.

[0010] The safety device according to the invention is used in the field of safety technology, in particular in the field of machine safety, and advantageously has a fail-safe design that complies with the normative requirements.

[0011] The safety device according to the invention comprises a safety switch and an actuator associated with it and movably arranged relative to it. The safety switch with the actuator can serve to secure a separating protective device.

[0012] A particularly advantageous separating protective device is a safety door that can close off access to a hazardous area of ​​a machine within the system. Generally, the separating protective device can also be a flap, a door, or the like.

[0013] The safety switch checks whether the actuator is in its closed position. For this purpose, the safety switch has an RFID unit that reads data from a transponder in the actuator when the actuator is in its closed position at the safety switch.

[0014] If such a safety switch is used to secure a separating protective device as access to a danger zone on the system, the operation of the system is only enabled if the safety switch determines that the actuator, and thus the separating protective device to which the actuator is attached, is in its closed position and, if applicable, whether this closed position is locked with the holding device.

[0015] According to the invention, the safety switch of the safety device has a magnetic holding device that holds the actuator closed when it is in its closed position. This holding device has a controllable magnet, such as an electromagnet or bistable magnet. The magnet generally forms a magnetic system, and in the following, without limitation of generality, reference is made to a magnetic system in the form of an electromagnet.

[0016] The safety switch has a control and evaluation unit that evaluates the data read from the transponder by the RFID unit, thus recognizing the closed position of the actuator and then activating the electromagnet to lock the actuator.

[0017] According to the invention, the read head of the RFID unit, which is essentially formed by a read coil, is mounted in the center of the pole surface, preferably exactly in the center of the pole surface of the electromagnet. Advantageously, the pole surface is a flat surface located on an end face of the safety switch.

[0018] Advantageously, the actuator has a corresponding flat metallic component, in particular an anchor plate, which, in the actuator's closed position, rests flat against the end face of the safety switch. The transponder is then mounted centrally in this component, so that, in the actuator's closed position, it is opposite the safety switch's read head, allowing the data to be reliably read from the transponder.

[0019] A first significant advantage of the invention is the compact design of the safety switch, which is achieved by mounting the reading head inside the electromagnet, thus eliminating the need for a separate installation space for the reading coil.

[0020] The reading head is magnetically isolated from the electromagnet, so that the electromagnet does not impair the function of the reading head.

[0021] Another significant advantage is that the read head can reliably read the data from the transponder even if the actuator is incorrectly positioned. For example, if the actuator is rotated around an axial axis, its transponder remains unchanged in front of the safety switch's read head.

[0022] This also results in improved tamper protection for the control and evaluation unit. If the read head were not located in the center of the electromagnet, but outside of it, a person could turn the electromagnet away from the actuator without this being detected by the read head failing to read the transponder data, thus potentially allowing, for example, a safety door to be opened uncontrollably.

[0023] According to an advantageous embodiment, components of the electromagnet are mounted in a multi-part housing made of plastic, whereby the positioning of the components of the electromagnet is achieved solely by means of mechanical supports of the housing.

[0024] The electromagnet is thus securely and without play fixed in position within the housing, which is achieved solely through the geometric design of the housing components.

[0025] Furthermore, no mounting hole needs to be provided in the body of the electromagnet.

[0026] Furthermore, the housing has fastening means for attaching the safety switch to a base, which is advantageous.

[0027] The components of the electromagnet are completely housed inside the casing, so that only the fastening means already present on the casing are used to fix the safety switch to a base.

[0028] According to a structurally advantageous embodiment, the housing has a housing body and a housing cover, wherein the housing body forms a trough in which a magnetic coil of the electromagnet is mounted.

[0029] Advantageously, both the housing body and the housing cover each consist of only one injection-molded plastic part.

[0030] An edge area of ​​the magnetic coil is positively locked in the tub.

[0031] Furthermore, the electromagnet has a magnetic body with projections extending from a base plate, the projections engaging in recesses in the housing body.

[0032] This also ensures a secure positioning of the electromagnet's components.

[0033] Furthermore, a seal is present, which rests on the side of the magnetic coil facing away from the tub, and which is mounted between the projections of the magnetic body.

[0034] This seal alone provides sufficient sealing for the electromagnet. Therefore, no potting compound is required to fill the interior of the housing of the safety switch.

[0035] Advantageously, the housing body has two side parts and two parallel webs connecting the side parts. Between the webs is a tubular recess extending axially along the housing body, which is designed to accommodate the read head.

[0036] The struts, connected via the tubular mount, stabilize the housing body, with the advantage that the struts and the tubular mount are formed as a single piece. The tubular mount not only ensures secure mounting of the read head but also provides magnetic isolation for it.

[0037] According to an advantageous embodiment, the safety sensor has an optical display unit which has exposed display elements on its front face.

[0038] It is advantageous that the housing contains a molded part made of plastic, which forms a cover for the electromagnet and which forms a light guide as part of the optical display unit.

[0039] In a structurally appropriate manner, the molded part has a base body that rests against the magnetic body of the electromagnet, from which arm segments protrude, the free ends of which form the indicator elements exposed on the front face of the safety switch.

[0040] Because the molded part fulfills a dual function, the number of parts for the safety switch is reduced and its assembly is simplified.

[0041] Advantageously, a circuit board is mounted inside the housing of the safety switch, on which light sources are arranged. Visible light emitted by the light sources is coupled into the arm segments of the light guide.

[0042] The light sources, which are advantageously formed by light-emitting diodes, together with the molded part form a structurally simple optical display unit.

[0043] The free ends of the arm segments are advantageously positioned in recesses of the housing, ensuring they are clearly visible from the outside of the safety switch. The light emitted by the light sources is guided through each arm segment of the molded part and emitted from a radiating surface at the free end of the arm segment. In this way, an optical display unit with multiple display elements can be implemented, capable of displaying various information, particularly status messages from the safety switch.

[0044] Advantageously, all electronic components of the safety switch, especially the control and evaluation unit, are mounted on the circuit board, resulting in a particularly compact design of the safety switch.

[0045] In particular, the safety switch has magnetic sensor means by which the armature plate of the actuator can be detected.

[0046] The invention will be explained below with reference to the drawings. The drawings show: Fig. 1: Exemplary embodiment of the safety device according to the invention with a safety switch and an actuator. Fig. 2: Safety device according to Fig. 1 with the actuator in a closed position. Fig. 3: Detailed view of the safety switch of the safety device according to the Fig. 1 and Fig. 2. Fig. 4: Exploded view of the components of the safety switch according to Fig. 3 a) in a first view. b) in a second view.

[0047] The Fig. 1 and Fig. Figure 2 shows an embodiment of the safety device 1 according to the invention with a safety switch 2 and an actuator 3. Fig. Figure 3 shows the safety switch 2 in a single view.

[0048] Safety device 1 serves in particular to secure a hazardous area of ​​a plant. It provides access to the hazardous area, which can be closed off with a protective door or, more generally, with a separating protective device.

[0049] The safety switch 2 is mounted in a stationary position on a frame that limits access. The actuator 3 is attached to the safety door and is therefore movable relative to the safety switch 2.

[0050] The components of the safety switch 2 are mounted in a housing 4, which is elongated in one longitudinal direction and flat in the other two directions.

[0051] The geometry of the actuator 3 is adapted to the geometry of the safety switch 2. The actuator 3 has a bracket 5 for mounting on the safety door. An anchor plate 6 is attached to the front of the bracket 5 facing the safety switch 2. The anchor plate 6 has the shape of a flat cuboid and is made of a metallic material. A transponder 7 is mounted in the center of the anchor plate 6.

[0052] Safety switch 2 contains a control and evaluation unit (not shown), which is formed by a fail-safe computer structure, in particular a two-channel structure with two computer units.

[0053] Furthermore, an RFID unit is provided in the safety switch 2, which includes a read head 8 with a read coil 19 (shown in the Fig. 4a, Fig. 4b). According to the invention, the reading head 8 is centrally mounted in a pole face 10 of an electromagnet, with which a magnetic holding device is formed. The pole face 10 lies on the end face of the safety switch 2 facing the actuator 3. The end of the reading coil 19 exposed on the end face of the safety switch 2 is covered with a cover 20 made of non-magnetic plastic.

[0054] The safety device 1 functions such that the closing position of the actuator 3, which is assumed when the safety door is closed (shown in Fig. 2) is detected when the transponder 7 is within the reading range of the RFID unit of the safety switch 2, allowing data to be read from the transponder 7. If the actuator 3 is detected in the closed position, the control and evaluation unit activates the electromagnet, so that the actuator 3 is held closed by the magnetic forces.

[0055] Since the read head 8 of the RFID unit is located in the center of the pole face 10 of the electromagnet, the transponder 7 of the actuator 3 is still positioned opposite the read head 8 in the reading area of ​​the RFID unit even if the actuator 3 is misaligned, as shown in Fig. 2 shows the situation in which the actuator 3 is slightly turned out from the front of the safety switch 2.

[0056] If the actuator 3 is detected in the closed position by the safety switch 2 and (optionally) the locking mechanism is activated, the safety switch 2 generates an output signal that enables the operation of the system.

[0057] The Fig. 4a, Fig. Figure 4b shows the construction of safety switch 2.

[0058] The housing 4 of the safety switch 2 consists of a housing body 11 and a housing cover 12, each made of an injection-molded plastic part. The injection-molded plastic parts are made of a non-magnetic plastic. The housing cover 12 can be attached to the housing body 11 using screws 13 to mount the housing 4.

[0059] A printed circuit board 15, on which the electronic components of the safety switch 2 are arranged, is mounted in the housing cover 12 with an intermediate layer of a cover seal 14. The power supply to these components is provided via an electrical connection 14a that opens onto the housing cover 12.

[0060] The housing body 11 comprises two side parts 16 as components of the injection-molded plastic part, which are connected by two parallel webs 17. The webs 17 are connected by a tubular receptacle 18 in which the read head 8 is guided.

[0061] The read head 8 has, in addition to the reading coil 19 and the cover 20, a receptacle 9 for connecting the reading coil 19 to the circuit board 15 and a hollow cylindrical cover 20 in which the components of the read head 8 are housed. This receptacle 9 is inserted into the tubular receptacle 18 for mounting the safety switch 2.

[0062] The electromagnet consists of a magnetic coil 21, to which a seal 22 is associated, and a magnetic body 23. The magnetic body 23, made of metallic material, has a base plate 23a, from the front of which, facing the end face of the safety switch 2, three parallel projections 23b extend over the entire width of the magnetic body 23. A central bore 23c is located in the base plate 23a. The bore 23c is, as Fig. 4a shows that the area of ​​the bridges 17 is breached.

[0063] Finally, a molded part 24, transparent to visible light, is provided, which on the one hand forms a cover for the magnetic body 23 of the electromagnet and on the other hand forms a light guide. The light guide consists of a plastic injection-molded part.

[0064] Light sources in the form of light-emitting diodes 25 are assigned to this light guide and are arranged on the circuit board 15.

[0065] The molded part 24 has a flat base body 24a, from which arm segments 24b project towards the front face of the safety switch 2. Each arm segment 24b is assigned a light-emitting diode 25. The base body 24a has a central bore 24c.

[0066] The light guide and the light-emitting diodes 25 form an optical display unit.

[0067] For mounting the safety switch 2, the circuit board 15 is stored in the housing cover 12. The solenoid coil 21 is inserted into a recess 26 of the housing body 11, where it is positively locked in place. Then the seal 22 is placed on the solenoid coil 21 and the solenoid body 23 is slid onto it, so that its projections 23b are supported between the webs 17 of the housing body 11 and their free ends are exposed at the front face of the safety switch 2. Fig. 3).

[0068] Then the cover is placed on the mounted electromagnet.

[0069] The reading head 8 is then guided through the bores 23c, 24c until the cover 20 of the reading head 8 lies in the plane of the front face of the safety switch 2 ( Fig. 3) The reading head 8 is magnetically isolated from the electromagnet.

[0070] When the housing cover 12 is placed on the housing body 11, electrical contact is advantageously made between the circuit board 15 and the magnetic coil 21.

[0071] When the safety switch 2 is fully assembled, the free ends of the arm segments 24b of the light guide protrude through recesses 27 in the housing 4 and thus form visible optical indicator elements on the outside of the safety switch 2 ( Fig. 3).

[0072] The manufacturing of safety switch 2 is therefore carried out without the use of a potting compound.

[0073] Mounting holes 28 are located on the side of the housing 4, into which fastening means in the form of fastening screws (not shown) can be inserted to fix the safety switch 2 to a base.

[0074] Advantageously, the safety switch 2 has at least one magnetic sensor with which the magnetic field is detected as it is changed by the armature plate 6. This enables armature plate detection.

[0075] The magnetic sensor can also be implemented using the magnetic coil 21 and the magnetic body 23. In this case, the current waveform is measured when the voltage across the magnetic coil 21 changes. The presence of the armature plate 6 can be detected from this current waveform, and the force acting on the armature plate 6 can also be measured. The measurement and evaluation are performed using the electronics on the circuit board 15. Reference symbol list 1 safety device 2 safety switches 3 actuators 4 cases 5 bracket 6 Anchor plate 7 transponders 8 Reading head 9th entry 10 Polar area 11 Housing body 12 Case covers 13 screw 14 Lid seal 14a connection 15 circuit boards 16 Side panel 17 Bridge 18 recording 19 Reading coil 20 lids 21 Magnetic coil 22 Seal 23 magnetic bodies 23a Base plate 23b advantage 23c bore 24 molded part 24a Basic body 24b arm segment 24c bore 25 LEDs 26 tubs 27 recess 28 Mounting holes QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 4 321 790 A1

[0006]

Claims

[1] Safety device (1) comprising a safety switch (2) having an RFID unit and an actuator (3) movable relative to the safety switch (2) with a transponder (7), wherein in a closed position of the actuator (3) data is read from the transponder (7) by means of the RFID unit and the safety switch (2) generates an output signal depending on this, and wherein the safety switch (2) has a magnetic locking device by means of which locking of the actuator (3) in its closed position can be effected, characterized by , that the locking device has an electromagnet having a pole surface (10), wherein a read head (8) of the RFID unit is arranged in the center of the pole surface (10). [2] Safety device (1) according to claim 1, characterized by , that the reading head (8) is positioned exactly in the middle of the pole surface (10). [3] Safety device (1) according to one of claims 1 or 2, characterized by , that the pole surface (10) is a flat surface that is arranged on an end face of the safety switch (2). [4] Safety device (1) according to any one of claims 1 to 3, characterized by , that components of the electromagnet are stored in a multi-part plastic housing (4). [5] Safety device (1) according to claim 4, characterized by , that the housing (4) has fastening means for attaching the safety switch (2) to a base. [6] Safety device (1) according to one of claims 4 or 5, characterized by , that the housing (4) has a housing body (11) and a housing cover (12), wherein the housing body (11) forms a trough (26) in which a magnetic coil (21) of the electromagnet is mounted and sealed. [7] Safety device (1) according to claim 6, characterized by, that the electromagnet has a magnetic body (23) with projections (23b) extending from a base plate (23a), wherein the projections (23b) engage in recesses (27) of the housing body (11). [8] Safety device (1) according to one of claims 6 and 7, characterized by , that a seal (22) is present which rests on the side of the magnetic coil (21) facing away from the tray (26) and which is mounted between the projections (23b) of the magnetic body (23), or that the seal (22) is mounted in the tray (26). [9] Safety device (1) according to any one of claims 6 to 8, characterized by , that the housing body (11) has two side parts (16) and two parallel webs (17) connecting the side parts (16), wherein between the webs (17) there is a tubular receptacle (18) extending in the axial direction of the housing body (11), which is designed to receive the read head (8). [10] Safety device (1) according to any one of claims 1 to 9, characterized by , that the reading coil (19) is mounted in a magnetically isolated manner from the electromagnet. [11] Safety device (1) according to any one of claims 3 to 10, characterized by , that the safety switch (2) has an optical display unit which has display elements exposed on its front face. [12] Safety device (1) according to claim 11, characterized by , that in the housing (4) there is a molded part (24) made of plastic which forms a cover for the electromagnet and which forms a light guide as part of the optical display unit. [13] Safety device (1) according to claim 12, characterized by, that the molded part (24) has a base body (24a) adjacent to the magnetic body (23) of the electromagnet, from which arm segments (24b) protrude, the free ends of which form the indicator elements exposed on the front face of the safety switch (2). [14] Safety device (1) according to claim 13, characterized by , that a circuit board (15) is stored in the housing (4) of the safety switch (2), on which light sources are arranged, wherein visible light emitted by the light sources is coupled into the arm segments (24b) of the light guide. [15] Safety device (1) according to claim 14, characterized by , that components of a control and evaluation unit are mounted on the circuit board (15), wherein the output signal of the safety switch (2) is generated in the control and evaluation unit and the electromagnet of the safety switch (2) is controlled. [16] Safety device (1) according to any one of claims 1 to 15, characterized by , that the actuator (3) has an anchor plate (6) made of a metallic material. [17] Safety device (1) according to claim 16, characterized by , that the safety switch (2) has magnetic sensor means by which the armature plate (6) of the actuator (3) can be detected.

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