EP1259969A1

EP1259969A1 - Safety switch device with a first and a second input circuit breaker

Info

Publication number: EP1259969A1
Application number: EP01905781A
Authority: EP
Inventors: Gerhard Ehrlich; Boris Kaufmann
Original assignee: Pilz GmbH and Co KG
Current assignee: Pilz GmbH and Co KG
Priority date: 2000-02-29
Filing date: 2001-02-16
Publication date: 2002-11-27
Anticipated expiration: 2021-02-16
Also published as: US20030057069A1; DE50100684D1; WO2001065577A1; JP2003526879A; AU2001233771A1; ATE250804T1; DE10009707A1; EP1259969B1; US6825579B2

Abstract

Two switches (12,14) are operated in common by control devices, e.g. an emergency push button. These in turn control timer devices (24a,24b) the time being set according to which switch contact is closed. The timers initiate controllers (28a,28b) which trip power supply switches (30a,30b). All are housed in a common cabinet (36) with the switches arranged in one plane

Description

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. Such 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. In this context, "safe" means that the device meets at least Category 3 of the European standard EN 954-1. For example, 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.

In the known safety switching device, the manipulated variable on the input side is a time constant which determines a delay time when switching off. Such 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.

In general, however, 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. However, it is disadvantageous that the production of the known safety switching device requires a high mechanical outlay, which is associated with correspondingly high costs. In addition, 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.

It is therefore an object of the present invention to provide a safety switching device of the type mentioned at the outset, which is of simpler and more space-saving design with consistently high safety requirements.

This object is achieved in the safety switching device mentioned above in that the switching contacts of the first and second input switches are arranged spatially in one plane.

In contrast to this, 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 consequence of this is that the two input switches have to be mounted in the housing of the safety switching device in two separate work steps. In contrast, 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.

In addition, as will be shown below on the basis of preferred embodiments of the invention, 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. However, it is still possible to use input switches that are separate from each other and thus redundant with each other. The required level of error security is therefore fully retained.

The above-mentioned task is therefore completely solved.

In a preferred embodiment of the invention, 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.

In a further embodiment of the measure mentioned above, the common carrier element can be rotated.

As an alternative to this, it is also conceivable to make the common carrier element adjustable in translation. In contrast, 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.

In a further embodiment of the aforementioned measures, 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.

As a result of this measure, 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. In a further embodiment of 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. In addition, 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. In addition, 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.

In a further embodiment of the invention, 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.

This measure enables a particularly simple mechanical construction, in particular if the switch contacts are arranged on a common carrier element as an actuator.

In a further embodiment of the measure mentioned above, the contact areas are conductor track structures applied to a circuit board. With this measure, 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. At the same time, it is possible to provide switching tracks that contain internal circuit logic by means of a suitable design of the conductor track structures. As a result, even complicated circuit diagrams can be implemented in a simple and reproducible manner. In addition, 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.

In a further embodiment of the invention, 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.

In a further embodiment of the invention, 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. This measure has the advantage that the number of required contacts for the two input switches can be reduced, which also enables a reduction in the space required. This also simplifies assembly.

In a further embodiment of the measure mentioned above, 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.

In a further embodiment of the invention, 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.

It goes without saying that the features mentioned above and those yet to be explained not only in the respectively specified combination but also in other combinations or can be used alone without leaving the scope of the present invention.

Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

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;

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; and

6 shows a preferred matrix structure in which switching contacts on the input side and on the output side of two mutually redundant input switches are arranged. 1, 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. In the present exemplary embodiment, 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. 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.

In the present exemplary embodiment, 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. Depending on these input signals and the redundant time constants, 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. Instead of the relay contacts 30a, 30b used here, 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.

In the following description of the further figures, the same reference numbers designate the same elements as in FIG. 1.

2, 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. In the interior of the housing 34, 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 Zugsziffern 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. In addition to further components 52, 54, 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 ,

As can be seen in FIG. 3, the safety switching device 10 according to the invention 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. Instead, 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. However, this arrangement only shows one possible exemplary embodiment. In alternative exemplary embodiments, the input switch unit 70 can also be contacted via a circuit board 58 arranged parallel to the front side 42. In contrast to the known safety switching device 40, such a circuit board 58 and a second circuit board 60 arranged parallel to it are not absolutely necessary here.

According to FIGS. 4 and 5, 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. 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. At their bottom in FIG. 4, 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.

The mechanical structure of such switches is known per se. For example, a mechanically comparable switch under the name "two-button coding switch" is sold by Fritz Hartmann Geratebau GmbH & Co. KG in 91083 Baiersdorf, Germany.

In contrast to these known two-button coding switches, in the present exemplary embodiment, however, there are two mutually separate 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.

In contrast, 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 same applies in an identical manner to the sliding contact pair 106, which cooperates with the conductor tracks 82 and 84. 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.

As can be easily understood, 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. As can be seen from FIG. 3, 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. However, the use of a two-button switch of the type shown is not absolutely necessary for the implementation of the invention. In alternative exemplary embodiments 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.

When using multi-position switches for the input switches 12 and 14, 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. In the present exemplary embodiment, 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. As an alternative to this, 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. On the basis of the matrix arrangement, 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. With the matrix structure 120 shown, due to the common input-side connection contacts 122 and the separate output-side connection contacts 132, 134, a faulty Reliable evaluation possible with a minimum number of connection contacts.

Claims

claims

1. Safety switching device with a first (12) and a second (12) input switch, the respective switching positions of which, redundantly to one another, define an actuating variable (Δt) on the input side, with at least one output switching element (30a, 30b) which is connected in an output circuit of the safety switching device ( 10), and with an evaluation and control unit (26) which controls the at least one output switching element (30a, 30b) as a function of the defined manipulated variable (Δt), switching contacts (104, 106) of the first (12) and of the second (14) input switch are coupled to one another in terms of their switching position via a common actuator (16), characterized in that the switching contacts (104, 106) of the first (12) and second (14) input switch are arranged spatially in one plane (110) are.

2. Safety switching device according to claim 1, characterized in that the actuator (16) includes a common support element (86) on which the switch contacts (104, 106) of the first (12) and second (14) input switch are arranged spatially offset from one another.

3. Safety switching device according to claim 2, characterized in that the common carrier element (86) is rotatably adjustable.

4. Safety switching device according to claim 2 or 3, characterized in that the common carrier element (86) is a carrier disc on which the switch contacts (104, 106) of the first (12) and second (14) input switch are arranged radially offset from one another.

5. Safety switching device according to one of claims 1 to 4, characterized in that the first (12) and second (14) input switch and the common actuator (16) are housed by a common switch housing (74).

6. Safety switching device according to one of claims 1 to 5, characterized in that the switching contacts (104, 106) of the first (12) and second (14) input switch are sliding contacts, which with the aid of the actuator (16) via fixed contact surfaces (78, 80, 82, 84) are movable.

7. Safety switching device according to claim 6, characterized in that the contact surfaces (78, 80, 82, 84) on a circuit board (76) are printed conductor structures.

8. Safety switching device according to one of claims 1 to 7, characterized in that the first (12) and second (14) input switches are each multi-position switches.

9. Safety switching device according to one of claims 1 to 8, characterized in that the first (12) and second (14) input switch on the input side (122) and have output-side (136, 138) connection contacts, which are each arranged in a matrix structure to one another.

10. Safety switching device according to claim 9, characterized in that the input-side connection contacts (122) of the first (12) and the second (14) input switch are interconnected.

11. Safety switching device according to one of claims 1 to 10, characterized in that the evaluation and control unit (26) is designed with two channels, a first channel (28a) with the first input switch (12) and a second channel (28b) with the second input switch (14) is connected.