Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/16—Indicators for switching condition, e.g. "on" or "off"
  • H01H9/161—Indicators for switching condition, e.g. "on" or "off" comprising light emitting elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H3/00—Mechanisms for operating contacts
  • H01H3/02—Operating parts, i.e. for operating driving mechanism by a mechanical force external to the switch
  • H01H3/022—Emergency operating parts, e.g. for stop-switch in dangerous conditions
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H2300/00—Orthogonal indexing scheme relating to electric switches, relays, selectors or emergency protective devices covered by H01H
  • H01H2300/052—Controlling, signalling or testing correct functioning of a switch

Definitions

• the invention relates to the field of control technology and safety technology.
• German patent application DE 19 919 012 A1 teaches a method for identifying activated, separable emergency stop command devices. The method is characterized in that an additional device is added to the emergency stop command device, which activates the specific color and/or the specific colors of the emergency stop command device only when it is properly connected to the system and/or machine connected in any way and voltage is applied. This generates a visual signal which indicates that the emergency stop command device is ready for operation.
• the international patent application WO 2017 139 817 A1 discloses a control system for electrically controlled systems.
• the control system comprises at least one portable, mobile handheld terminal for displaying information and for inputting control commands by an operator.
• the hand-held operating device has at least one manually operable safety switching element, with the safety switching element being assigned a lighting device.
• the control system includes a lighting control device, which is designed for electrically and/or electronically controlled adjustment of a visually perceptible luminous intensity of the lighting device.
• the emergency stop switch includes two switches S1 and S2, which can be actuated via an actuating element 5 from an actuated to a non-actuated position.
• the two switches S1 and S2 are connected to safety electronics.
• An optical display element LM usually an LED, is provided in the actuating element 5, the optical display element LM being driven in two channels and made dynamic with two-channel voltage feedback is monitored.
• the optical display element LM can comprise a single display element or a multiplicity of display elements.
• Monitoring is carried out using a first sensor M1 and a second sensor M2.
• the first sensor Ml measures a current of the optical display element LM.
• the second sensor M2 measures a voltage of the optical display element LM.
• the safety electronics SE thus monitors the function of the optical display element LM by driving the optical display element LM with current or voltage and measuring the current or voltage with the first or second sensor M1, M2. If there is a discrepancy between control and measurement, the safety electronics SE conclude that the emergency stop switch is malfunctioning. [0008] However, this type of monitoring harbors risks with regard to a reliable statement about the function of the optical display element LM. It is known that, due to various factors, optical display elements such as LEDs become defective and a current or a voltage is detected via the feedback or feedback signal, but without the LED emitting an optical signal.
• This type of monitoring is particularly risky, especially in the case of emergency stop switches on mobile emergency stop systems.
• Such mobile emergency stop systems are still rare and have to meet particularly high safety requirements.
• the mobile emergency stop systems must also comply with the particularly high measures and guidelines in accordance with the applicable and known standards fulfill.
• the reliable functioning of the optical display element is a particularly important safety feature.
• the present application discloses a monitoring system for an optical display element of an emergency stop switch, the monitoring system comprising an actuating element with an optical display element and an optical sensor.
• Safety electronics are connected to the optical display element and the optical sensor. It can thereby be ensured that the optical display element functions reliably and is not faulty in order to avoid fatal consequences for life and limb.
• the optical display element LM can comprise a single display element or a multiplicity of display elements.
• the safety electronics includes a safe output and a safe input and is connected to the optical display element via the safe output.
• the optical sensor is connected via the safe input.
• Safe output thus means that, despite an error at the output, it is still possible to switch off safely and an error at the output is reliably detected. This is the case, for example, if one of the channels of the safety electronics has a fault (from low to high resistance) and can no longer be switched. An error of this type is clearly identified by the feedback signal. Nevertheless, it can still be switched off safely with the other of the channels.
• a safe input also means that the input can still be read and an error at the safe input is reliably detected. For example, the absence of a feedback signal at the safety electronics via at least one channel can be understood as an error.
• the monitoring system further comprises an optical waveguide, which carries an optical signal from the optical display element to the optical sensor.
• the optical sensor includes at least one of a photoresistor, a photodiode, and a phototransistor.
• the optical sensor can thus be optimally adapted to an individual application.
• the optical display element comprises a plurality of display elements and the optical sensor comprises a plurality of optical sensors.
• the number of optical display elements and optical sensors is therefore not limited. The number of optical sensors or optical display elements depends on the safety requirements and risk potential of a monitored system (plant, machine, engine, etc.).
• the risk assessment determines the required PL (Performance Level) or SIL (Safety Integrity Level). These are determined by the structure of the safety electronics, component reliability, error detection, etc.
• the safe output comprises at least one first output contact and at least one second output contact.
• the secure input includes at least a first input contact and at least a second input contact. This makes it possible to connect several components to the safety electronics.
• the present disclosure includes a method for a monitoring system for a visual indicator of an emergency stop switch.
• the method includes generating an optical signal by feeding an optical display element with electrical current or an electrical voltage via safety electronics.
• the method also includes measuring the optical signal via an optical sensor using the safety electronics. The emitted optical signal of the optical display element is measured.
• the method also includes interrupting the generation of the optical signal for a period of time, and measuring the interruption of the optical signal via the optical sensor using the safety electronics. This step can be repeated or is repeated to increase the security of the system.
• the method also includes comparing the generated optical signal with the measured optical signal in the presence of the electrical current or Voltage through the safety electronics. Based on the comparison, a conclusion is drawn about the functionality of the optical display element and thus about the system.
• the method further includes outputting a warning signal when the comparison of the generated optical signal and the measured optical signal deviates in the presence of the electrical current.
• the method ensures that the optical display element LM, when it is supposed to light up, also lights up or is active. In return, this method ensures that the optical display element LM does not light up when it is not supposed to light up or is inactive. If there are discrepancies when comparing the generated optical signal with the measured optical signal, this means that the optical display element LM, as a source of information about the operating status of a system, can no longer be relied on. As a result, the system's emergency stop function can no longer be relied on, which leads to a wide variety of effects. The impact can range from a warning signal to a complete shutdown of the system, for example. If, in a non-limiting example, the safety electronics SE detects a malfunction of the display element LM, the emergency hat function of the actual emergency stop switch is triggered, since this mobile emergency stop system can no longer be relied on.
• the interruption of the generation of the optical signal can be repeated in chronological succession in the case of a single-channel connection between safety electronics and optical display element. This can increase the security of the system.
• the interruption of the generation of the optical signal can be repeated simultaneously in the case of a multi-channel or n-channel connection between safety electronics and optical display element.
• the security of the system can be further increased.
• the safety electronics when measuring the optical signal, at least one of a parameter of the optical signal or a presence of the optical signal is measured by the safety electronics.
• the optical signal parameter includes at least one of a light spectrum, luminous flux, illuminance, or particular modulation. This makes it possible to set different configurations of the optical signal and to detect them using the optical sensor.
• the warning signal is output or the malfunction is detected at a receiving point in a wireless or wired manner. This allows the warning signal to be sent to a specific location to increase safety.
• Figure 1 is a schematic representation of a prior art emergency stop switch.
• Figure 2 is a schematic representation of an emergency stop switch monitoring system according to a first aspect.
• Figures 3A to 3D represent first aspects of safety electronics.
• Figures 4A and 4B represent second aspects of the safety electronics.
• Figure 5 is a schematic representation of an emergency stop switch monitoring system according to a second aspect.
• Figure 6 shows examples of optical sensors.
• FIGS. 7 is a flowchart for a method for a monitoring system for the emergency stop switch of FIGS. 2 and 5.
• FIG. 2 is a schematic representation of an emergency stop switch monitoring system 100 according to a first aspect.
• the monitoring system 100 includes an actuating element 5 and safety electronics SE.
• the actuating element 5 comprises a first switch S1, a second switch S2, an optical display element LM and an optical sensor OS.
• the actuating element 5 is at least one of a switch, lever, knob or button for turning, switching (toggling), pressing or pulling.
• the first switch S1 and the second switch S2 are connected to the safety electronics SE.
• the first switch S1 and the second switch S2 depend on the design of the actuating element 5 .
• the first switch S1 and the second switch S2 of the types of operating element 5 mentioned above are known and will therefore not be described in further detail here.
• the optical display element LM is able to generate or convert an optical signal based on an electrical signal, such as a current and/or a voltage.
• the visual indicator LM is, in a non-limiting example, an LED (Light Emitting Diode) or a light bulb.
• the visual display element LM comprises at least one individual visual display element.
• the optical display element LM can also include a large number of individual display elements LM.
• the frequency spectrum of the optical signal ranges from visible light to near and mid-infrared and can be modulated by the SE safety electronics.
• the optical display element LM is connected to the single-channel or multi-channel safe outputs of the safety electronics SE via one or more channels.
• the safety electronics SE controls the optical display element LM with the electrical signal and can influence or modulate the electrical signal. By influencing the electrical signal, one or more parameters of the optical signal can be adjusted.
• the adjustable parameters of the optical signal are at least one of a light spectrum, luminous flux, illuminance or special modulation. This increases the safety of the emergency stop switch and an application of the emergency stop switch can be customized.
• Figures 3A to 3D represent selected examples and options, which do not limit the invention, of how the safety electronics SE can be set up in two or more channels at the safe output A with regard to a shutdown of the system or machine.
• the safety electronics SE includes multiple safe inputs E and multiple safe outputs A, these can Inputs E and outputs A are referred to as channels K.
• channels K can Inputs E and outputs A are referred to as channels K.
• the safety electronics SE only includes a safe input E and a safe output A, forming a channel, this is referred to as an external single-channel system, consisting of the display element LM and/or the optical sensor OS. Any number of channels can still be present internally.
• a feedback signal BACK is tapped off and fed back to the safety electronics SE in order to monitor the switching of the channels K with regard to safety or the degree of safety.
• the feedback signal BACK represents a basic realization of the safe output A.
• the feedback signal BACK is required for the basic realization of the safe output A. Errors can be reliably detected by the safety electronics SE via the feedback signal BACK and thus form the safe output A.
• the safety electronics SE are designed with two channels, with the first channel K1 and a second channel K2.
• the first safe output A includes the first channel Kl and the second channel K2.
• the display element LM is connected via both channels K1 and K2 to an output contact A1+ and on the other hand to a second output contact A1- to the safety electronics SE.
• FIG. 3B shows a second aspect of the arrangement from FIG. 3A, but with the difference that the second channel K2 is arranged at the second output contact Al- of the safe output A.
• FIG. 3C represents a further aspect when a first display element LM1 and a second display element LM2 are connected to the safety electronics SE for monitoring.
• the configuration shown corresponds to the configuration from FIG. 3A, but in two-channel form.
• the first display element LM1 is connected separately via both channels K1 and K2 to the output contact A1+ and, on the other hand, to the second output contact A1- to the safety electronics SE.
• the second Display element LM2 is connected separately via both channels Kl and K2 to an output contact A2+ and on the other hand connected to the safety electronics SE at a second output contact A2-.
• This example shows how a large number of display elements LM can be connected and monitored separately at a safe output of the safety electronics SE.
• Fig. 3D shows a second aspect of the arrangement of Fig. 3B, but with the difference that the first display element LM1 and the second display element LM2 are connected in series and connected via the first and second output contacts A1+, Al- to the Security electronics are connected.
• the first channel Kl is provided at the first output contact A1+ and the second channel K2 is provided at the second output contact Al ⁇ .
• FIGS. 4A and 4B represent selected examples and options, which do not limit the invention, of how the safety electronics SE can be set up with one or n channels at the safe input E.
• Input E can be monitored via the switch and the feedback. If n-1 channels fail, a valid input signal is still detected. For example, if two out of three channels fail, the safety electronics SE can still reliably detect the input signal via the feedback signal BACK.
• FIG. 4B shows another aspect of how multiple optical sensors OS can be connected to the safe input E of the safety electronics SE.
• a first optical sensor OS1 is connected to the safety electronics SE via the first channel Kl.
• a second optical sensor OS2 is connected to the safety electronics SE via the second channel K2, separately from the first channel Kl. This results in a completely two-channel system in which there is an internal and external two-channel system.
• FIG. 5 shows a schematic representation of the monitoring system 100 for an emergency stop switch according to a second aspect.
• the monitoring system 100 according to the second aspect differs from the monitoring system 100 according to the first aspect in that the optical sensor OS is not accommodated in the actuating element 5 .
• the optical sensor OS of the monitoring system 100 according to the second aspect is provided on the safety electronics SE.
• the optical signal of the optical display element LM is routed from the optical display element LM via an optical waveguide LWL to the optical sensor OS.
• the structure of the remaining components corresponds to that of the monitoring system 100 according to the first aspect. For this reason, the same components are provided with the same reference numbers and are not repeated at this point.
• the optical sensor OS includes at least one of a photoresistor OSa, photodiode OSb and phototransistor OSc.
• the reason for this function is the internal photoelectric effect in a layer consisting of an amorphous semiconductor. Compared to other light sensors, photoresistors react very slowly.
• the photodiode OSb is a semiconductor diode that converts light in the visible, infrared, or ultraviolet range at a pn junction or pin junction by the internal photoelectric effect into an electric current or an electric voltage to the to receive information transmitted with the optical signal.
• the phototransistor OSc comprises a light-sensitive photodiode with a connected amplifier transistor. In terms of circuitry, the light-sensitive photodiode is connected in parallel to the collector-base connections of the transistor. Incident light allows a small current to flow due to the internal photoelectric effect. This current is amplified in the transistor by the current amplification factor to the collector current. At this point, reference is made to the literature with regard to the known photoelectric effect.
• step S 1 shows a flow chart for a method for a monitoring system 100 for the emergency stop switch according to the first and second aspect.
• the safety electronics SE by driving the optical display element LM by means of an electrical signal generates the optical signal.
• the electrical signal is tapped off at or after each of the channels K as a feedback signal BACK and fed back to the safety electronics SE in order to monitor the switching of the channels K with regard to safety or the degree of safety.
• the optical signal is measured with the optical sensor OS.
• step S2 at least one of the parameters of the optical signal or a presence of the optical signal is measured.
• at least one of a light spectrum, luminous flux, illuminance or special modulation of the optical signal is measured.
• step S3 the activation of the optical display element LM by means of an electrical signal is interrupted for a period of time t ü via the safety electronics SE.
• the interruption can be repeated in succession.
• the interruption can be repeated simultaneously or with a time offset. Due to the staggered interruptions, cross-circuits between the safe outputs A, the safe inputs E and between the safe outputs A and the safe inputs E can be detected. This interruption/s is/are measured with the at least one optical sensor OS.
• step S4 the generated electrical signal is compared with the measured optical signal by the safety electronics SE.
• the interruption and measurement of the electrical signal as well as the comparison are referred to as "dynamization".
• the function of the safe input/inputs E and safe output/outputs A can be continuously monitored as a result of the dynamization. Any errors that may occur can thus be detected at the latest at the next time interval of the dynamization.
• the degree of dynamization i.e. how often and when a time interval is repeated, is proportional to the security requirements of systems.
• the safety requirement depends on the respective potential dangers or dangerous situations. So will For example, the safety electronics and their functions in nuclear power plants are monitored almost constantly and dynamically.
• the dynamization can therefore also be viewed as a type of function test. If it is technically ensured that the system is set up as a redundant system in a separate, isolated design, so that, for example, no cross-circuits or ground faults can occur mechanically, dynamization can also be completely dispensed with.
• a warning signal is output if the generated optical signal, depending on the electrical signal, deviates from the measured optical signal.
• the warning signal is output wirelessly or wired to a receiving station.
• the warning signal can be an analog or digital signal.
• the receiving station can generate a control command and/or an acoustic or visual signal from the warning signal. For example, the control command is to stop the machine.

Landscapes

• Photometry And Measurement Of Optical Pulse Characteristics (AREA)
• Switches Operated By Changes In Physical Conditions (AREA)
• Electronic Switches (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Audible And Visible Signals (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=82308251

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Country Status (5)

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Family Cites Families (8)

• 2021
  • 2021-06-09 DE DE102021114870.7A patent/DE102021114870A1/de active Pending
• 2022
  • 2022-06-07 DE DE202022002929.2U patent/DE202022002929U1/de active Active
  • 2022-06-07 EP EP22734876.0A patent/EP4352769A1/de active Pending
  • 2022-06-07 CA CA3221892A patent/CA3221892A1/en active Pending
  • 2022-06-07 WO PCT/EP2022/065330 patent/WO2022258575A1/de active Application Filing
  • 2022-06-07 KR KR1020247000007A patent/KR20240018567A/ko unknown

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