Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H19/00—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand
  • H01H19/001—Thumb wheel switches
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
  • H01H47/002—Monitoring or fail-safe circuits
  • H01H47/004—Monitoring or fail-safe circuits using plural redundant serial connected relay operated contacts in controlled circuit

Definitions

• Safety switching device with a first and a second input switch
• the present invention relates to a safety switching device with a first and a second input switch, the respective switching positions of which define a control variable on the input side, with at least one output switching element which is arranged in an output circuit of the safety switching device, and with an evaluation and control unit which Dependent on the defined manipulated variable controls the at least one output switching element, switching contacts of the first and second input switches being coupled to one another with regard to their switching position via a common actuator.
• a safety switching device is sold by the applicant of the present invention under the type designation PNOZ XV2.
• the safety switching devices in the sense of the present invention include both independent safety switching devices and complex safety controls, for example based on a safe PLC control.
• Devices of this type are used primarily in the industrial sector in order to carry out switching operations in a safe manner.
• "safe" means that the device meets at least Category 3 of the European standard EN 954-1.
• devices of this type are used in response to the actuation of an emergency stop button or the opening of a protective door to shut down or otherwise convert a machine system from which there is a danger into a safe state. Since failure of the device in such a situation results in an immediate danger to people or even material values, very high demands are made with regard to the fail-safety of safety switching devices. This leads to a high outlay associated with high costs in the development and production of safety switching devices.
• the manipulated variable on the input side is a time constant which determines a delay time when switching off.
• a delay time is required, for example, in order to be able to move movable drives into a safe rest position in a controlled manner when a machine system is switched off.
• the time constant is used in the known safety switching device set by two mutually redundant rotary switches which are arranged one below the other or one behind the other on a common shaft. This structure is explained in more detail below with reference to FIG. 2.
• the manipulated variable to be set can be any input parameter relevant for a safety switching device.
• the known safety switching device fulfills the safety requirements of the EN 954-1 standard in particular because the two input switches each separately define the desired time constant. Due to the resulting redundancy, an error in one of the switches can be reliably detected by the evaluation and control unit.
• the production of the known safety switching device requires a high mechanical outlay, which is associated with correspondingly high costs.
• the construction of the known safety switching device requires a comparatively large amount of space, which prevents miniaturization of generic devices or at least makes it difficult.
• the switching contacts of the two input switches in the known safety switching device are located in two planes offset parallel to one another.
• the two input switches have to be mounted in the housing of the safety switching device in two separate work steps.
• the two input switches in the inventive safety switching device can be installed in a single step. This simplifies assembly and the safety switching device according to the invention can be produced more cost-effectively.
• the installation space required for the two input switches can be considerably reduced, so that the safety switching device according to the invention can be implemented with a smaller overall size.
• the actuator includes a common support element on which the switching contacts of the first and second input switches are arranged spatially offset from one another.
• This measure has the advantage that the switching contacts of the two input switches are coupled in a structurally very simple and therefore inexpensive manner. Clutches, gears or other measures for transmitting a switching movement from the first input switch to the second can therefore be dispensed with without the risk of different operator settings.
• the common carrier element can be rotated.
• the common carrier element is adjustable in translation.
• the preferred embodiment has an advantage above all if the two input switches are multi-position switches, since the existing switching contacts can be arranged in a space-saving manner relative to one another and thus in a more compact manner.
• the common carrier element is a carrier disk on which the switching contacts of the first and second input switches are arranged radially offset from one another.
• the two separate input switches can be integrated in a small mechanical and space-saving manner in a common mechanical structure. This also simplifies the assembly of the input switches in the housing of the safety switching device according to the invention.
• the first and second input switches and the common actuator are surrounded by a common switch housing.
• This measure has the advantage that the separate input switches form a common, inherently redundant component which can be installed in the safety switching device according to the invention in a very simple and therefore inexpensive manner.
• the reliability is increased still further, since the risk of damage to the redundant switch arrangement during assembly or during subsequent intervention in the safety switching device is reduced.
• the safety-relevant switch arrangement is particularly well protected in this way against external environmental influences, such as, for example, contamination. This also contributes to increasing error security.
• the switching contacts of the first and second input switches are sliding contacts which can be moved over fixed contact surfaces with the aid of the actuator.
• the contact areas are conductor track structures applied to a circuit board.
• the two input switches can be produced in a fail-safe manner even in very large numbers, which minimizes the costs for the two input switches.
• even complicated circuit diagrams can be implemented in a simple and reproducible manner.
• the measure increases error safety again, since conductor track structures are not subject to any or, if need be, extremely little wear during operation of the device, so that a subsequent error that occurs only during operation of the device is largely ruled out. The risk of subsequent cross-circuits or short-circuits is also reduced.
• the first and second input switches are multi-position switches.
• This measure is particularly simple to implement in combination with the previously mentioned embodiments of the invention. It has the advantage that the safety switching device according to the invention receives multiple setting options, which improves its range of use and its adaptability. As a result, larger numbers of pieces can be produced, which result in a cost reduction.
• the first and second input switches have connection contacts on the input side and on the output side, each of which is arranged in a mat structure.
• the input-side connection contacts of the first and second input switches are connected to one another.
• This measure further reduces the number of connections required for the two input switches. For example, this measure makes it possible to have 16 switching positions which are redundant to one another, i.e. a total of 32 switch positions with only a total of 12 connection contacts. As a result, the installation space of the arrangement according to the invention can be reduced again and the assembly can be simplified.
• the evaluation and control unit is designed with two channels, a first channel being connected to the first input switch and a second channel being connected to the second input switch.
• This measure has the advantage that the safety switching device is designed to be redundant throughout, whereby a particularly high level of error safety can be achieved.
• FIG. 1 shows the circuit structure of a safety switching device according to the invention in the form of a safety switching device
• FIG. 2 shows a safety switching device, as sold by the applicant of the present invention, in cross section
• FIG. 3 shows the safety switching device according to the invention from FIG. 1 in cross section;
• FIG. 4 shows an input switch unit of the safety switching device from FIG. 3 along the line IV-IV;
• FIG. 5 shows the input switch unit of the safety switching device from FIG. 3 along the line V-V;
• a safety switching device according to the invention in the form of a safety switching device is designated in its entirety by reference number 10.
• the safety switching device 10 has two mutually redundant input switches 12 and 14, which are coupled to one another with regard to their switching position via a common actuator 16 which is only shown schematically here.
• the input switches 12, 14 are integrated in an identical manner n each into a voltage divider, each of which consists of a resistor 18a, 18b and a respective resistor group 20a, 20b.
• the resistance groups 20a, 20b contain three resistors arranged in parallel with one another with different resistance values.
• An operating voltage which is 24 V in the present exemplary embodiment lies across the two voltage dividers.
• the two voltage dividers Depending on the respective switching position of the input switches 12, 14, the two voltage dividers generate an output signal which is fed to a timing element 24a, 24b via a respective additional resistor 22a, 22b.
• the timing elements 24a, 24b redundantly define one another and, depending on the voltage obtained in each case, a time constant which is fed to an evaluation and control unit 26. The voltage obtained depends on the respective switching position of the two input switches 12, 14.
• the evaluation and control unit 26 is designed with two channels and has a microcontroller 28a, 28b in each channel.
• the microcontrollers 28a, 28b also evaluate further input signals, not shown here, which are generated, for example, by an emergency stop. Buttons or a protective door can be generated.
• the microcontrollers 28a, 28b each control output switch contacts 30a, 30b.
• the output switch contacts 30a, 30b are arranged in series with one another in a power supply path of a machine system 32.
• the invention is not restricted to safety switching devices with contact-type outputs.
• semiconductor elements can also be used as output switching elements.
• the entire safety switching device 10 is accommodated in a housing 34 which has connecting terminals 36 for connecting the power supply and the machine system 32 in a manner known per se.
• a generic safety switching device as it is sold by the applicant of the present invention, is designated in its entirety by reference number 40.
• the housing 34 of the safety switching device 40 reveals a front side 42 and two side walls 44, 46 in the present cross-sectional illustration.
• component carriers in the form of so-called boards 48, 50 are arranged along the two side walls 44, 46.
• 48 individual components with the loading Switzerlandsziffern 52 and 54 denotes.
• the comparatively large housing of a relay 56, which contains the output switching contacts 30a, 30b, is likewise shown as an example on the circuit board 50.
• the reference numbers 58 and 60 denote two further boards which are fastened parallel to the front side 42 and parallel to one another between the boards 48 and 50.
• the input switches 12 and 14 are located on these two boards. These are rotary switches which are fastened one below the other or one behind the other on a common shaft 62.
• the shaft 62 emerges on the front side 42 of the housing 34 and is connected to a rotary knob 64 there.
• the shaft 62 thus forms a common actuator for the two input switches 12 and 14.
• the switching contacts of the two input switches 12 and 14, as can be seen from the illustration in FIG. 2, are arranged in n different planes 66, 68 offset parallel to one another ,
• the safety switching device 10 differs from the known safety switching device 40, inter alia, in that the two boards 58, 60 arranged parallel to the front side 42 can be dispensed with.
• the two input switches 12 and 14 are in this exemplary embodiment in a common input switch unit 70, the structure of which is explained in more detail below with reference to FIGS. 4 and 5.
• the input switch unit 70 is connected to the circuit board 48 via contact pins 72.
• this arrangement only shows one possible exemplary embodiment.
• the input switch unit 70 can also be contacted via a circuit board 58 arranged parallel to the front side 42.
• such a circuit board 58 and a second circuit board 60 arranged parallel to it are not absolutely necessary here.
• the input switch unit 70 has a switch housing 74 in which the mechanical actuation parts are accommodated.
• the switch housing 74 is arranged on a circuit board 76.
• the circuit board 76 has on its side facing the switch housing 74 a plurality of conductor tracks 78, 80, 82, 84 running along circular tracks.
• Each of the conductor tracks 78 to 84 is each connected to a contact pin 72, the connections for the conductor tracks 82 and 84 m in the present exemplary embodiment being carried out on the rear side of the circuit board 76, which is represented by the dotted line.
• a circular carrier disk 86 is arranged in the switch housing 74 of the input switch unit 70 and can be rotated in the direction of the arrow 88.
• the actuation of the carrier disk 86 takes place optionally by one of two buttons 90, 92, which are each arranged tangentially and parallel to one another along two side walls of the switch housing 74.
• the carrier disk 86 On the side facing away from the circuit board 76, the carrier disk 86 has a star-shaped structure 94 into which cams 96, 98 of the two buttons 90, 92 can engage.
• the buttons 90, 92 are supported with springs 100, 102 against the rear wall of the switch housing 74.
• the actuation of one of the two buttons 90, 92 thus has the consequence that the Carrier disc 86 is rotated by one tooth of star-shaped structure 94 in the direction of arrow 88.
• sliding contact pairs 104 and 106 which are arranged radially offset from one another, on the side of the carrier disk 86 facing the circuit board 76.
• the sliding contact pair 104 cooperates with the conductor tracks 78 and 80, while the sliding contact pair 106 cooperates with the conductor tracks 82 and 84. If the sliding contact pair 104 is at an angular range above the diagonal 108 according to FIG. 5, it establishes a conductive connection between the otherwise electrically isolated conductor tracks 78 and 80. In this case, the input switch 12 between the contact pins 72 and 73 is closed.
• the sliding contact pair 104 is in an angular position which is below the diagonal 108 according to FIG. 5, there is no conductive connection between the conductor tracks 78 and 80, so that the switch between the contact pins 72 and 73 is open.
• the lead Tracks 78 to 84 are arranged on the circuit board 76 to one another in such a way that the input switches 12 and 14 realized in this way each switch simultaneously and redundantly to one another.
• the switching logic of the input switch unit 70 results primarily from the arrangement of the conductor tracks 78 to 84 on the circuit board 76.
• the present exemplary embodiment is deliberately simply chosen to explain the invention. However, it goes without saying that redundant multi-position switches can also be realized by a suitable choice of the conductor track structure.
• the input switch unit 70 is a particularly preferred exemplary embodiment of a safety switching device 10 according to the invention.
• the sliding contact pairs 104, 106 and the conductor track structures 78 to 84 i.e. all switching contacts of the two input switches 12 and 14, thereby within a common level 110.
• the use of a two-button switch of the type shown is not absolutely necessary for the implementation of the invention.
• the carrier disk 86 can also be adjusted, for example, via a shaft 62 and a rotary knob 64, as is known from the safety switching device 40.
• the number of contact pins required basically increases twice as much as the number of desired switching positions. There is also a factor of two for the redundant design of the safety relay 10. At 16 64 switch pins or corresponding connection options were required. This number can be reduced by suitable coding of the switch positions using a matrix structure.
• FIG. 6 shows a preferred exemplary embodiment of a matrix structure 120 for the input switches 12 and 14.
• the matrix structure 120 has four connection contacts 122, which are supplied with switching contacts 124, 126 of the two input switches 12 and 14 in parallel.
• the switching contacts 124, 126 which are assigned to one another are shifted by one step in each case, i.e. here the uppermost switching contact 124 of the input switch 12 in FIG. 6 is connected to the second uppermost switching contact 126 of the input switch 14 in FIG. 6.
• the switching contacts 124, 126 of the two input switches 12 and 14 can, however, also be connected to one another in a manner shifted by different increments.
• There is also a step size of zero, i.e. a mirror-image assignment of the switching contacts 124, 126 to one another is possible.
• the output-side switch contacts 132, 134 of the two input switches 12 and 14 are routed separately from one another to output-side connection contacts 136, 138.
• the current switching position of the input switches 12 and 14 can be determined by comparing or evaluating the signals at the input-side connection contacts 122 and the output-side connection contacts 136, 138.

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• Keying Circuit Devices (AREA)
• Switch Cases, Indication, And Locking (AREA)
• Programmable Controllers (AREA)
• Air Bags (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 2000
  • 2000-02-29 DE DE10009707A patent/DE10009707A1/de not_active Withdrawn
• 2001
  • 2001-02-16 AU AU2001233771A patent/AU2001233771A1/en not_active Abandoned
  • 2001-02-16 EP EP01905781A patent/EP1259969B1/fr not_active Expired - Lifetime
  • 2001-02-16 DE DE50100684T patent/DE50100684D1/de not_active Expired - Lifetime
  • 2001-02-16 JP JP2001564374A patent/JP2003526879A/ja active Pending
  • 2001-02-16 AT AT01905781T patent/ATE250804T1/de not_active IP Right Cessation
  • 2001-02-16 WO PCT/EP2001/001728 patent/WO2001065577A1/fr active IP Right Grant
• 2002
  • 2002-08-22 US US10/225,941 patent/US6825579B2/en not_active Expired - Fee Related

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