Safety switching device

Abstract

A safety switching device (10) for the safety-related interruption of a safety circuit (18) comprises a housing (12) and electronics (14) arranged in the housing. The electronics (14) have two switching elements (16) which can be arranged in the safety switching circuit (18) via a first, second, third, and fourth connection (20; 201-204) on the housing and close the circuit redundantly when a control signal is present at each switching element (16). Furthermore, a fifth connection (20; 205) and a sixth connection (20; 206) are provided on the housing (12) to which a first and a second input signal can be applied, corresponding to the control signals of the switching elements (16), so that when the first and second input signals are present at the fifth and sixth connections (205, 206), the safety circuit (18) is closed.In addition, the electronics (14) arranged in the housing (12) have a further electrical element (28) which is designed to draw energy for its own operation from an electrical signal applied to the first, third, fifth and / or sixth terminal (201, 203, 205, 206).

Description

[0001] The present invention relates to a safety switching device for the safety-related interruption of a safety circuit.

[0002] Safety relays are the origin and backbone of safe automation technology. As standalone devices, safety relays monitor safety functions such as emergency stops, safety doors, light barriers, light grids, pressure-sensitive mats, and many more. Safety relays thus perform defined safety functions and ensure, for example, the controlled and therefore safe stopping of a movement, the position monitoring of movable guards, and the interruption of a closing movement in the event of an intervention. Safety relays are primarily used to reduce risks and initiate a safe and reliable response in the event of a fault or violation of protection zones. Safety relays can be found in almost all areas of mechanical and plant engineering, primarily where the number of safety functions is manageable.

[0003] Essentially, a safety switching device is a switch that switches a safety circuit on or off depending on an input signal. The input signals are supplied by safety sensors or safety transmitters (emergency stop buttons, light barriers, etc.) and fed to the safety switching device when the safety sensors indicate a safe state, whereupon the safety switching device closes the safety circuit. If one of the input signals is missing, the safety switching device interrupts the safety circuit, which usually shuts down a technical system or prevents it from starting up. Alternatively, interrupting the safety circuit can also lead to another reaction from the technical system that brings about a safe state.

[0004] In contrast to a normal switching relay, with a safety switching device – when properly wired – neither a fault in the device itself nor a fault caused externally by a sensor or actuator can lead to the loss of the safety function. For this purpose, a safety switching device has additional special circuits or special relay technology compared to a normal switching relay to ensure safe switching even in the event of a fault. The typical design of a safety switching device is redundant. Two relays with positively guided contacts provide the safe switching contacts, which are also referred to as safe outputs or safety outputs. Two input circuits each control one of the two internal relays.

[0005] Since a separate safety switching device is generally used for each safety function, the number of safety switching devices increases with each safety function in a technical system, and thus also the space required in the associated control cabinet. The increasing number of required safety switching devices leads to the demand to minimize the space required by a single safety switching device. In addition to the actual switching elements, the external connections are of crucial importance. The more external connections required on a safety switching device, the greater the installation space required by the device.

[0006] It is therefore an object of the present invention to provide an improved safety switching device which requires little installation space while providing the greatest possible range of functions, reduces cabling effort and prevents cabling errors.

[0007] The object is achieved by a safety switching device with a housing and electronics arranged in the housing, wherein the electronics have two switching elements which can be arranged in the safety switching circuit via a first, second, third and fourth connection located on the housing and close this redundantly when a control signal is applied to each switching element, wherein a fifth connection and a sixth connection are provided on the housing, to which a first input signal and a second input signal can be applied, which correspond to the control signals of the switching elements, so that when the first and the second input signal are applied to the fifth and sixth connection, the safety circuit is closed, wherein the electronics arranged in the housing have a further electrical element which is designed to supply energy for its own operation to a power supply connected to the first, the third,the fifth and / or sixth terminal to obtain the electrical signal.

[0008] It is therefore an idea of ​​the present invention to provide a safety switching device configured to extract electrical energy from a connected signal. The extracted energy is used to operate an electrical element within the safety switching device. In other words, an electrical element draws the current required for its intended use from the energy extracted from the signal.

[0009] The safety relay can, for example, be a safety relay specifically designed for active sensors that actively provide an input signal from which additional energy can be drawn. The provided energy can, in addition to controlling the internal switching elements, contribute to the power supply of at least one other element of the safety relay. This advantageously eliminates the need for external connections for a separate power supply.

[0010] The eliminated connections can help ensure that the safety relay can be installed in a smaller housing than a comparable safety relay with external supply connections. In particular, the housing width, which is relevant to the required installation space, can be reduced. It is also conceivable to use the freed-up connections for other functions. For example, it is possible to increase the number of safe outputs of the safety relay without having to use a separate device or resort to a device that provides further external connections for additional safe outputs. The reduced number of external connections can thus contribute to an improvement by allowing the use of a smaller housing with the same functionality or by providing additional functionality with the same housing size.Furthermore, the reduced number of external connections simplifies the wiring of the safety relay and prevents wiring errors. This completely solves the problem posed at the beginning.

[0011] In a further embodiment, the electrical signal can be the first and / or the second input signal.

[0012] According to this embodiment, the energy for the additional electrical element can be taken from one or both input signals. In this case, the safety switching device can be configured for special use with active sensors. Active sensors here are safe sensors that provide an input signal independently of the safety switching device's power supply. Active sensors can have an output signal switching device (OSSD) to generate the input signal. Output signal switching devices, as part of a safe sensor, in particular an electro-sensitive protective device (ESPD), can provide a signal that is fail-safely interrupted if the sensor part of the safe sensor responds during normal operation.By specializing the safety relay for active sensors, connections for outgoing signals intended for passive sensors and supplied with potential by the safety relay can be eliminated. Consequently, in this version, additional external connections in addition to the power supply connections can be omitted or assigned differently.

[0013] In a further embodiment, the electrical signal can be a potential switched on by the switching elements.

[0014] In this configuration, the power for the additional electrical element can be drawn from a potential present at the first or third terminal. The applied potential is a potential in the safety circuit that is switched through by the switching elements in the safe state and serves, for example, to control contactors in a power supply of a technical system monitored by the safety switching device. In this case, the electrical signal can be a 24 V DC voltage commonly used in industrial environments, which the safety switching device uses to supply power to the additional electrical component.

[0015] In a further embodiment, the electrical signal can be galvanically isolated from the further electrical element.

[0016] With this design, the safety relay can be decoupled from the electrical signal, thereby protecting the safety relay from overvoltages caused by the electrical signal. The coupling can be inductive or capacitive. This effectively contributes to increasing the safety relay's fail-safe performance.

[0017] In a further embodiment, the further electrical element can be an operating indicator, in particular an LED.

[0018] Safety relays can have indicators that show the operating status of the device. These indicators may be required by standards for proper operation of the safety relay. According to a further embodiment, the energy for operating the indicator can be taken from the electrical signal, so that no additional power supply is required for the indicator. This embodiment is particularly advantageous in cases where the indicator is the only electrical element besides the safety relay that requires active power, as a separate power supply is completely unnecessary. In the case of an operating status indicator, this can also advantageously be coupled directly to the corresponding input signals or the potential to be switched.

[0019] In a further embodiment, the further electrical element may have a first status indicator that indicates a status of one of the switching elements.

[0020] With this design, a channel status indicator can also be easily supplied with an operating voltage, eliminating the need for a separate power supply. Thus, this design can also contribute to simplifying the necessary device electronics.

[0021] In a further embodiment, the further electrical element can be an electronic element that performs a safety-related task in the safety switching device, for example a microcontroller.

[0022] With this design, the energy absorbed by the signal can be used to power a microcontroller used to control and monitor the safety relay. This design eliminates the need for a separate power supply for the safety relay, even if the safety relay has an extended range of functions that require a microcontroller.

[0023] In a further embodiment, the further electrical element can be electrically connected to the first, the third, the fifth and / or the sixth terminal.

[0024] According to this embodiment, the additional electrical element is connected to one or more terminals to which an electrical signal can be applied. Depending on the type of electrical signal, the electrical element can be connected to the terminals directly or via an additional component. In this way, a power supply via externally applied signals can be implemented simply and efficiently.

[0025] In a further embodiment, the safety switching device can further comprise an electrical component which is connected to the further electrical element and establishes a voltage and / or power supply for the operation of the electrical element.

[0026] According to this embodiment, a further electrical component can be provided that converts the energy absorbed by the electrical signal to operate the further electrical element. The electrical component can be a resistor that, when applied with a voltage, acts as a power source, for example, for an LED. The use of a rectifier or a voltage regulator is also conceivable. This embodiment enables a wider range of possible electrical signals that can be used as an energy source.

[0027] In a further embodiment, the safety switching device can further comprise an energy storage device which buffers the energy for the operation of the electrical element, wherein the electrical signal charges the energy storage device.

[0028] According to this embodiment, an energy storage device can be provided, which is connected upstream of the further electrical element in order to provide the energy required for the electrical element. The energy storage device can be an inductive or capacitive component that buffers or smooths the voltage or current required for the operation of the other electrical component. This allows different electrical signals to be used as an energy source. This embodiment thus contributes to the effective adaptation of the device to a larger number of electrical signals.

[0029] In a further embodiment, a seventh terminal can be provided on the housing, to which a reference potential for the electronics can be connected.

[0030] In this embodiment, at least one additional terminal can be provided to provide a uniform reference potential. The reference potential can be used to easily generate a supply voltage from the electrical signal if it corresponds to a potential. It goes without saying that a potential connected to the second or fourth terminal can also be used as a reference potential without requiring a seventh terminal.

[0031] In a further embodiment, the further electrical element can be powered exclusively from the energy taken from the electrical signal.

[0032] With this design, no additional power source is required to operate the additional electrical element. This design thus contributes particularly advantageously to reducing the number of external connections and simplifying the electronics.

[0033] In a further embodiment, the housing can have two side surfaces and a plurality of functional surfaces connecting the side surfaces, which together define an enclosed interior in which the electronics are arranged, wherein a distance between the side surfaces defines a maximum width of the housing and the connections are arranged on the functional surfaces, and wherein in particular the maximum width is equal to or less than 22.5 mm.

[0034] Safety relays can have a housing suitable for installation in a control cabinet. Such a housing is usually several times smaller than the depth and height of the housing. The housing can, for example, be box-shaped with two side surfaces and four functional surfaces connecting the side surfaces. When properly installed in a control cabinet, one of the functional surfaces (front surface) faces the user and houses the external connections. The two side surfaces define the width of the housing. Reducing the number of external connections allows the housing width to be advantageously reduced.

[0035] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0036] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 a safety switching device according to a first embodiment of the present disclosure in a schematic representation, Fig. 2 a safety switching device according to a second embodiment of the present disclosure in a schematic representation, Fig. 3 shows a possible application for a safety switching device 10 according to the present disclosure in a simplified schematic representation, Fig. 4 an embodiment of a housing of a safety switching device according to the present disclosure in a simplified perspective view, and Fig. 5 a reference example of a safety switching device according to the state of the art.

[0037] Fig. Figure 1 shows a schematic representation of a safety switching device according to a first exemplary embodiment of the present disclosure. The safety switching device is designated in its entirety by reference numeral 10.

[0038] The safety switching device 10 has a housing 12 and electronics 14 arranged in the housing 12. The electronics 14 has two switching elements 16, in particular positively driven relays, whose contacts can be arranged in a safety circuit 18. The contacts of the two switching elements 16 are led to the outside via connections 20 on the housing 12. The safety switching device 10 has at least a first connection 201, a second connection 202, a third connection 203, and a fourth connection 204 in order to redundantly guide the safety circuit via the contacts of the switching elements 16.

[0039] The safety switching device 10 further comprises a first input circuit 22 and a second input circuit 24, which can also be contacted externally via connections 20 on the housing 12. The first input circuit 22 can be connected externally via a fifth connection 205, and the second input circuit 24 can be connected externally via a sixth connection 206, with the input circuits 22, 24 preferably being connectable externally exclusively via the fifth and sixth connections 205, 206. A first input signal from a safety sensor (not shown here) can be received via the fifth connection 205, and a second input signal from a safety sensor (not shown here) can be received via the sixth connection 206. The first and second input signals are then present at the fifth and sixth connections 205, 206 of the safety switching device 10 when the safety sensor signals a safe state of a technical system to be monitored.

[0040] If the first and second input signals are properly applied to the fifth and sixth terminals 205, 206, the input circuits 22, 24 provide a control signal 26 for the two switching elements 16, on the basis of which the switching elements 16 close the safety circuit 18. If one of the input signals fails or the safety switching device 10 otherwise detects a fault in the input signal or other devices of the safety switching device 10, no control signal 26 is provided, so the switching elements 16 interrupt the safety switching circuit 18 and thus force the establishment of a safe state in the technical system to be monitored.

[0041] The safety switching device 10 further comprises a further electrical element 28. The further electrical element 28 can be part of the electronics 14 and, for example, be arranged on a common circuit board together with the switching elements 16 and the input circuits 22, 24. The further electrical element 28 is an electrical or electronic component that, in addition to the switching elements 16, performs a function of the safety switching device 10. In various exemplary embodiments, the further electrical element 28 can be a display, implemented, for example, by one or more light-emitting diodes 30. Alternatively or additionally, the further electrical element 28 can also be a control element, such as a microcontroller 31 or an FPGA, and assume control functions of the safety switching device.Such a control element could, for example, perform additional safety-related tasks of the safety switching device 10, such as continuous comparison of input signals, cross-circuit detection, or diagnostic functions. Of course, the additional electrical element 28 is not limited to these functions.

[0042] The further electrical element 28 is further configured to draw energy for its own operation from an electrical signal applied to the first, third, fifth, and / or sixth terminal 201, 203, 205, 206. The electrical signal can correspond to one or both input signals, or to a signal conducted via the safety circuit 18, in accordance with the assignment described above. The electrical signal can, for example, be a static potential applied to the aforementioned terminals, from which energy can be drawn directly. Alternatively, dynamic signals (clock signals) can also be applied to the terminals, from which energy can be drawn from static components or as effective values.

[0043] The additional electrical element 28 can be a safety-related device that contributes to meeting the normative requirements that may be placed on the safety switching device. For example, it is conceivable that a safety switching device only meets the normative requirements if the safety switching device can visualize its state or the state of the switching elements (channels) for a user via a display. It is also conceivable that, in addition to safely switching the safety circuit, the safety switching device must perform additional functions that an electrical (integrated) circuit provides in order to meet a specific safety level.

[0044] Regardless of the type of additional electrical element 28, the energy required for this purpose is taken from the electrical signal present at the aforementioned terminals. The safety switching device preferably does not have an additional power supply, such as a voltage or current source, for operating the additional electrical element 28. By omitting an additional power supply for the additional electrical element 28, the external connections provided for this purpose on the housing 12 can advantageously be omitted or used for other purposes.

[0045] Compared to known safety switching devices, additional connections can be eliminated with this safety switching device by assuming that the safety sensors connected to input circuits 22, 24 are active safety sensors. Active safety sensors are characterized by the fact that they can provide an input signal independently of the safety switching device 10. This means that they are devices that have their own power supply and a so-called output signal switching device (OSSD), which can provide a safe input signal depending on a sensor of the safety switching device. In contrast to passive safety sensors, such as emergency stop buttons, such active safety sensors do not depend on the safety switching device providing a switching potential for the safety sensors.Accordingly, by specializing in active sensors, additional connections on the housing for providing switching potentials are eliminated. Each input circuit thus requires only one connection on the housing to receive the input signal of an active safety sensor.

[0046] The restriction to active safety sensors also has the advantage that, due to its function, an electrical signal is present as an input signal at the safety switching device, from which energy can be drawn that is not provided by the safety switching device. In an output signal switching device (OSSD), the provided input signal is referred to as an OSSD signal, whose electrical properties are generally defined by standards for various applications. Powering the additional electrical element based on an OSSD signal is therefore easily possible, as the power supply can be adapted to the electrical properties. The additional element 28 can, for example, be selected so that it can be directly coupled to the OSSD signal in order to be energized when the OSSD signal is present.However, it is also conceivable that a further component is provided, which is connected between the connection of the electrical signal and the further electrical element 28 or in parallel with the further electrical element 28 in order to set a suitable voltage supply for the further electrical element 28. The further component can be a simple resistor or a rectifying element such as a diode. Furthermore, a voltage regulator can be connected between the connection of the electrical signal and the further electrical component 28 in order to set a defined and constant voltage at the further electrical element 28. However, the present disclosure is not limited to a specific form of energy extraction.

[0047] In addition to the aforementioned first to sixth terminals 201 to 206, the safety switching device can optionally have further terminals, as the exemplary embodiment shown here shows. For example, the safety switching device can have a seventh terminal 207 and an eighth terminal 208. The seventh and eighth terminals 207, 208 form a further safe output, analogous to the two safe outputs formed by the first and second terminals 201, 202 and the third and fourth terminals 203, 204. A safe output is thus formed by two terminals 20 each, which are connected via the switching contacts of the switching elements 16. In the preferred embodiment here, the safety switching device 10 thus has three safe outputs.

[0048] A ninth terminal 209, which is coupled to the electronics 14 of the safety switching device 10, can also be provided on the safety switching device 10. For example, a reference potential can be applied to the ninth terminal 209, which together forms a supply voltage for the further electrical element 28. The reference potential can, for example, be a common ground potential for the electronics 14. In principle, such a potential could also be applied to the second or fourth terminal, so that no additional connection would be required. However, measures would then have to be taken to galvanically decouple the reference potential from the further electronics 14.

[0049] In addition, the safety switching device 10 can have further devices, circuits, and connections, as indicated by the dashed lines in the present embodiment. A further circuit can be, for example, a start circuit 32, via which a switch-on process can be controlled. The start circuit 32 can receive a start signal via a tenth connection 210 and be designed such that the switching elements 26 close the safety circuit 18 only when the start signal is present. A diagnostic device 34 is also conceivable, which provides a signal at an eleventh connection 211 that indicates the current switching state of the switching elements.

[0050] Finally, the safety switching device 10 can also have a twelfth and a thirteenth terminal 212, 213, which, like the safe outputs (terminals 201-204; 207-208), are connected via the contacts of the switching element 16, but not via positively guided normally open contacts, but rather via positively guided normally closed contacts. Normally open contacts are contacts that close a connection between the contacts when the switching element is actuated, i.e., in the switched-on state, and normally closed contacts are contacts that open a connection between the contacts when the switching element is actuated. The twelfth and thirteenth terminals 212, 213 can be used as a feedback circuit and connected, for example, to the start circuit 32 to prevent a faulty restart.

[0051] According to the first exemplary embodiment, the safety switching device 10, as shown here, can have thirteen connections. However, for the primary function of the safety switching device 10, namely the safe interruption of a safety circuit depending on redundant input signals, six connections are sufficient, as shown above. Therefore, in the safety switching device 10 according to the first exemplary embodiment, the housing 12 can be made smaller compared to a safety switching device that usually has ten or more external connections to provide the primary function. Alternatively or additionally, freed-up connections can be used for other tasks. An example of this is shown in Fig. 2 shown.

[0052] Fig. Figure 2 shows a schematic representation of a safety switching device according to a second exemplary embodiment of the present disclosure. The safety switching device is also designated in its entirety by reference numeral 10.

[0053] In Fig. 2 are functionally identical elements with the same reference numbers as in Fig. 1 and a detailed description of these elements is omitted below.

[0054] The safety switching device 10 according to the second exemplary embodiment comprises a housing 12, an electronics unit 14, two switching elements 16, a plurality of terminals 20, and a first and a second input circuit 22, 24. The plurality of terminals 20 includes the first to sixth terminals 201 to 206. Furthermore, the safety switching device 10 comprises the further electrical element 28, which, as previously described in connection with the first exemplary embodiment, draws energy for its own operation from an electrical signal applied to the first, third, fifth, or sixth terminal.

[0055] As in the first embodiment, the seventh to thirteenth terminals 207 to 213 can optionally be provided in the same way in the second embodiment.

[0056] The second embodiment differs from the first embodiment in the design of the switching elements 16. Here, the switching elements 16 have additional positively guided normally open contacts, which are routed to the outside via a fourteenth, fifteenth, sixteenth, and seventeenth terminal 214, 215, 216, 217 on the housing 12. The fourteenth and fifteenth terminals 214, 215 thus form a fourth safe output, and the sixteenth and seventeenth terminals 216, 217 form a fifth safe output of the safety switching device 10.

[0057] In the safety switching device 10 according to the second exemplary embodiment, five safe outputs can thus advantageously be provided without significantly increasing the number of external connections 20 compared to a safety switching device of the prior art. This is possible because the described energy extraction eliminates or frees up external connections in the input circuits or in a power supply of the safety switching device.

[0058] Fig. 3 shows a simplified schematic representation of a possible application for a safety switching device 10 according to the present disclosure.

[0059] Fig. Figure 3 shows an automated robot 38 as the technical system 36 to be monitored. The robot 38 has a defined workspace within which the robot arm 40 can move. Access to the workspace is secured by a safety sensor. The safety sensor here is a non-contact protective device (ESPD) in the form of a light curtain 42. The light curtain 42 has a first component 44 and a second component 46, between which light beams can be exchanged. The light curtain 42 only signals a safe state when the exchange of light beams occurs in a defined manner and no other fault has occurred in the light curtain 42. Signaling is provided via an output signal switching device (OSSD) 48, which provides a redundant output signal (OSSD signal 50) when the light curtain is operating correctly and no access to the technical system 36 has been detected.

[0060] A safety switching device 10 according to an embodiment of the present disclosure is connected via conductors 52 to the output signal switching device 48 of the light grid 42. The safety switching device 10 thus receives an OSSD signal 50 redundantly as a first and second input signal and switches the switching elements 16 depending thereon. The switching elements 16 are integrated into a safety circuit 18 in the manner described above, so that redundant contactors 54 are energized when the OSSD signal 50 is provided by the light grid 42. The normally open contacts 56 of the contactors 54 can in turn be arranged in a power supply of the technical system 36, so that the technical system 36 is only supplied with power when and for as long as the output signal switching device 48 provides the OSSD signal 50.In this way, the safety switching device 10, in cooperation with the light grid 42, provides a safety function that monitors access to the technical system 36.

[0061] The safety switching device 10 can be arranged together with other control devices in a control cabinet 58. In particular, further safety switching devices can be arranged in the control cabinet 58, via which additional safety functions are implemented. The further safety switching devices are represented here by dashed lines. The individual safety switching devices can be arranged side by side on a top-hat rail 60. The connections 20 for the wiring and further display elements 62 are each arranged on front surfaces 64 of the safety switching devices, which face a user after installation in the control cabinet 58. The width of the front surfaces 64 essentially defines the required overall width 66 of a safety switching device and is essentially dependent on the number of connections 20 required on the respective front surface 64.For example, a standard dimension for the width 66 of safety switching devices is 22.5 mm.

[0062] By eliminating the external connections 20 on the safety switching devices according to the present disclosure, the actual installation space required for the safety switching devices in the control cabinet 58 can be reduced. At the same time, wiring is simplified if no external power supply is required for the safety switching devices. In principle, the reduced number of connections 20 can effectively reduce wiring errors.

[0063] Fig. 4 shows a simplified perspective view of an embodiment of a housing of a safety switching device according to the present disclosure.

[0064] According to Fig. 4, the safety switching device 10 is arranged in a substantially rectangular housing 12. The box-shaped housing 12 has two opposite side surfaces 68, 70 and, in this example, four functional surfaces 72, 74, 76, 78 connecting the side surfaces 68, 70. When the safety switching device 10 is properly installed in a control cabinet, the functional surface 72 corresponds to a front surface 64 of the safety switching device 10. For installation, the housing 12 can have, for example, a bracket for fastening to a top-hat rail 60 on a functional surface 78 opposite the front surface 64.

[0065] The essential operating and display elements as well as the external connections 20 of the safety switching device are arranged on the functional surface 72, which serves as the front surface and faces a user after installation in a control cabinet. In the present exemplary embodiment, six external connections 20 and a display element 62 are provided on the front surface 72 of the safety switching device 10. The six external connections 20 can correspond to the previously described first to sixth connections 201 to 206 and can be implemented, for example, by screw or spring-loaded terminals commonly used in automation technology. The display element 62 can, for example, have three displays that indicate the operating state of the safety switching device as a whole as well as the states of the two switching elements.The displays of the display element 62 may be further electrical elements 28 within the meaning of this disclosure, the power supply of which is effected via an electrical signal applied to the terminals 201 to 206 in the manner described above.

[0066] By reducing the number of external connections 20 in the manner described above, a width 66, which corresponds to a maximum distance between the side surfaces 68, 70, can be advantageously reduced if the connections 20 are arranged on the front surface 72 of the housing 12 in the manner customary in automation technology. In this way, a safety switching device 10 can be provided which is suitable for special safety functions, for example in conjunction with ESPE, as shown in Fig. 3, is suitable for this purpose and has a smaller overall width of 66 mm than comparable standard devices. Furthermore, wiring effort and wiring errors can be advantageously reduced with such a safety switching device.

[0067] Fig. Finally, Figure 5 shows a reference example of a safety switching device 80 according to the prior art. The safety switching device 80 differs from the safety switching device 10 according to the first exemplary embodiment of the present disclosure by a power supply 82 for the internal electronics, which can be coupled to an external power supply via two terminals 84, 86 on the housing 88.

[0068] Furthermore, the reference example differs in that corresponding devices for the previously described energy extraction from an electrical signal present at the remaining terminals, as well as the use of the extracted energy to supply an electrical element of the safety switching device that does not correspond to the switching elements, are missing. Rather, electrical elements within the meaning of this disclosure in the safety switching device 80 according to the prior art are supplied by the additional power supply 82.

[0069] The safety switching device 80 according to the prior art further comprises two input circuits 90, 92, each of which has two external connections on the housing 88. The additional connections 94, 96, compared to the input circuits 22, 24, serve to provide output signals that can be switched via passive safety sensors and fed back to the inputs 98, 100. The safety switching device 80 is therefore not designed for specific use with active safety sensors, but for general use with passive or active safety sensors.

[0070] The safety switching devices 10 according to the first and second exemplary embodiments are characterized by a reduced number of external connections and a different assignment of the available connections. However, it goes without saying that the exemplary embodiments represent the subject matter of the invention only by way of example, and the invention is defined solely by the following patent claims.

Claims

[1] Safety switching device (10) for the safety-related interruption of a safety circuit (18), comprising: a housing (12) and electronics (14) arranged in the housing, wherein the electronics (14) comprises two switching elements (16) which can be arranged in the safety switching circuit (18) via a first, second, third and fourth connection (20; 201-204) located on the housing (12) and which close said circuit redundantly when a control signal is applied to each switching element (16), wherein a fifth terminal (20; 205) and a sixth terminal (20; 206) are provided on the housing (12), to which a first input signal and a second input signal can be applied, which correspond to the control signals of the switching elements (16), so that when the first and the second input signal are applied to the fifth and sixth terminals (205, 206), the safety circuit (18) is closed, and wherein the electronics (14) arranged in the housing (12) has a further electrical element (28) which is designed to extract energy for its own operation from an electrical signal applied to the first, the third, the fifth and / or the sixth terminal (201, 203, 205, 206). [2] Safety switching device according to claim 1, wherein the electrical signal is the first and / or the second input signal. [3] Safety switching device according to claim 1 or 2, wherein the electrical signal is a potential to be switched on by the switching elements (16). [4] Safety switching device according to one of claims 1 to 3, wherein the electrical signal is galvanically isolated from the further electrical element (28). [5] Safety switching device according to one of claims 1 to 4, wherein the further electrical element (28) has an operating display, in particular an LED. [6] Safety switching device according to one of claims 1 to 5, wherein the further electrical element (28) has a first status indicator which indicates a status of one of the switching elements (16). [7] Safety switching device according to one of claims 1 to 6, wherein the further electrical element (28) is an electronic element, in particular a microcontroller (31), and performs a safety-related task of the safety switching device (10). [8] Safety switching device according to one of claims 1 to 7, wherein the further electrical element (28) is electrically connected to the first, the third, the fifth and / or the sixth terminal (201, 203, 205, 206). [9] Safety switching device according to one of claims 1 to 8, further comprising: an electrical component which is connected to the further electrical element (28) and establishes a voltage and / or current supply for the operation of the electrical element. [10] Safety switching device according to one of claims 1 to 9, further comprising: an energy storage device that buffers the energy for the operation of the electrical element, whereby the electrical signal charges the energy storage device. [11] Safety switching device according to one of claims 1 to 10, wherein a seventh terminal (207) is provided on the housing (12), to which a reference potential for the electronics (14) can be connected. [12] Safety switching device according to one of claims 1 to 11, wherein the further electrical element (28) is powered exclusively from the energy taken from the electrical signal. [13] Safety switching device according to one of claims 1 to 12, wherein the housing (12) has two side surfaces (68, 70) and a plurality of functional surfaces (72, 74, 76, 78) connecting the side surfaces, which together define an enclosed interior in which the electronics (14) are arranged, wherein a distance between the side surfaces defines a maximum width (66) of the housing (12) and the terminals (20) are arranged on one of the functional surfaces (72, 74, 76, 78). [14] Safety switching device according to one of claims 1 to 12, wherein the maximum width (66) is equal to or less than 22.5 mm. [15] Safety switching device according to one of claims 1 to 14, wherein the first, second, third and fourth terminals (201-204) located on the housing represent two safe outputs, each of which can interrupt the safety switching circuit (18), wherein six further terminals (207, 208; 214-217) are provided on the housing (12), which together form three further safe outputs. [16] Safety switching device according to one of claims 1 to 15, wherein the first input signal is a coded signal, in particular an OSSD signal (50), and is provided by an output signal switching device (48) of a protective device, in particular a non-contact protective device. [17] Safety switching device according to one of claims 1 to 16, wherein the terminals (20) of the safety switching device are screw or spring terminals.

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