Safety detector and safety detection system including the same

Abstract

The present invention relates to a safety detector (20) comprising a detection module (IN) configured to read a control signal (S_IN) at an input, the detector comprising two power supply terminals, a first control input (I1) and a first control output (C1), a first safety output (OSSD1) and a second safety output (OSSD2), and a first free terminal and a second free terminal, the detector comprising: - a second control input (I2) connected to the first free terminal and a second control output (C2) connected to the second free terminal, - a test module configured to apply in particular a first test sequence, the first test sequence comprising disabling the first control output (C1) and testing a start loop (B_ST) connected between the second control output (C2) and the first control input (I1).

Description

Technical Field

[0001] The present invention relates to a safety detector and a safety detection system including the detector. The present invention also relates to a control method implemented in the safety detector. Background Art

[0002] There are various types of safety detectors. For example, a safety detector can take the form of a safety light curtain, a safety switch with a tow cable, or a so-called contactless safety detector. The latter is a contactless device that includes a sensor (also referred to as a "reader") and a transponder (also referred to as a "coded actuator") controlled by a microcontroller.

[0003] A safety detector can include two redundant safety output terminals (referred to as OSSD output terminals, "Output Signal Switching Device"). When these output terminals are in the off state, the application protected by the safety detector can operate. For example, in the case of a contactless safety detector, the sensor is mounted on a fixed part of the protective device of the facility to be protected (e.g., the door frame for entering a hazardous area), and the transponder is mounted on a moving part of the protective device.

[0004] There is no contact between the transponder and the sensor. The use of radiofrequency technology (RFID) allows communication between the sensor and the transponder. The sensor and the transponder have been pre-paired (e.g., during manufacturing), and the sensor loads a unique code into the transponder that will be sold with it. The recorded digital code is the only "key" accepted by the paired sensor.

[0005] When the transponder enters the radiofrequency field generated by the sensor, the sensor detects the transponder and reads the data in the transponder's memory.

[0006] If the code from the transponder requested by the sensor is correct, the two redundant safety output terminals from the sensor enter the off state (hereinafter referred to as the ON state), which means that the protective device of the facility is closed and that the machine can operate.

[0007] If the transponder leaves the magnetic field generated by the sensor (e.g., when the door of the hazardous area to be protected is opened), the two redundant safety output terminals of the sensor enter the on state (hereinafter referred to as the OFF state) to stop the machine.

[0008] Some of the safety detectors described above are also designed to operate autonomously. In other words, their two safety outputs are directly connected to a contactor equipped with mechanical contacts, without any intermediate relays or programmable controllers (PLCs). Generally speaking, the connection system available on safety detectors is an M12-type connector with eight pins.

[0009] Generally speaking, a safety detector can have two available operating modes. When applied to contactless safety detectors, these two operating modes are as follows:

[0010] In the first operating mode, called automatic start, as long as the paired transponder appears in the detection area of the sensor, the sensor is in a state called RUN after startup without operator intervention. When the sensor is turned on, the sensor thus undergoes an initialization phase during which its safety outputs are in the OFF state. If no faults are detected and if the transponder is located in the detection area of the sensor, the detector automatically enters the RUN state and the two safety outputs enter the ON state. Subsequently, if the transponder leaves the detection area of the sensor, the sensor goes from the RUN state to the STOP state and the two safety outputs are switched to the OFF state. The sensor remains in the STOP state until the paired transponder re-enters the detection area (without faults being detected). In the latter case, the sensor then automatically returns from the STOP state to the RUN state and the two safety outputs can be switched to the ON state.

[0011] In the second operating mode, called manual start, when turned on, the sensor undergoes an initialization phase during which its safety outputs are in the OFF state. If no faults are detected after an automatic test, it enters the START / RESTART state. To enter the RUN state and make its safety outputs enter the ON state, the paired transponder must be in the detection area, no faults must be detected, and the operator must actuate and release the start button (monitor start).

[0012] When the sensor is in the RUN state, if the transponder leaves the detection area, the sensor will automatically enter the STOP state and its safety outputs go from the ON state to the OFF state. If the paired transponder returns to the detection area (and if no faults are detected), the sensor returns to the START / RESTART state and the safety outputs of the sensor remain in the OFF state until the button is actuated.

[0013] A safety detector with autonomous operation includes an external circuit known as EDM ("External Device Monitoring"), which allows verification of whether switching devices such as contactors respond correctly to the safety output of the detector.

[0014] The EDM-type circuit monitors external contactors connected to the two safety outputs of the detector. To this end, it monitors the normally-closed (NC) contacts of these external contactors. If the external circuit is not closed, the detector must not enable its safety outputs.

[0015] It may now be desirable to connect an emergency stop device to the autonomous type of safety detector as described above in order to include additional safety functions therein. However, in its autonomous version (in other words, without using safety logic blocks), since the detector includes only eight electrical terminals, the addition of the emergency stop function can prove to be complex. Generally, the terminals of the detector are wired in the following manner:

[0016] - Two power terminals are connected to the power supply;

[0017] - The two terminals of the safety output are each connected in a redundant manner to the contactors of the application;

[0018] - One or two terminals for the EDM monitoring function are connected to the external circuit.

[0019] Therefore, only two or three terminals remain available. However, in order to connect an emergency stop device with two redundant contacts, four additional terminals are required. Thus, in the conventional configuration of the detector, it is not suitable for being associated with an emergency stop device while retaining its current functions.

[0020] Accordingly, an object of the present invention is to provide a safety detector configured with only eight connection terminals and designed to be associated with an emergency stop device, as well as a solution allowing the emergency stop device to be associated with such a safety detector.

[0021] The solution of the present invention provides significant advantages when the safety detector is of the autonomous type, in other words, when it includes integrated intelligence sufficient to directly control the contactors of a machine without using safety logic blocks. Summary of the Invention

[0022] This object is achieved by a safety detector including a detection module configured to read a control signal at an input, the detector including two power terminals, a first control input and a first control output, a first safety output and a second safety output, and a first free terminal and a second free terminal, the detector further including:

[0023] - A second control input connected to the first free terminal and a second control output connected to the second free terminal,

[0024] - A test module configured to apply a first test sequence and / or a second test sequence, the first test sequence including disabling the first control output and testing the start-up loop connected between the second control output and the first control input, and the second test sequence including disabling the second control output and testing the start-up loop connected between the first control output and the second control input.

[0025] According to a specific embodiment, the test module is configured to execute a third test sequence, which includes enabling the second control output and reading the state of the second control input.

[0026] According to another specific embodiment, the test module is configured to execute a fourth test sequence, which includes reading the states of the first control output and the second control output.

[0027] According to another specific embodiment, the detector includes a control and processing unit configured to run the test module.

[0028] According to another specific embodiment, the control and processing unit is configured to run:

[0029] - A module for reading the state of each control input;

[0030] - A module for determining the operating state considering the state of its control input;

[0031] - One or more modules for controlling its safety output and control output according to the determined operating state.

[0032] According to a variant embodiment, the safety detector can be contactless and includes:

[0033] - A sensor and a transponder paired with the sensor,

[0034] - When the transponder appears in the detection area of the sensor, the control signal is modified.

[0035] According to another variant embodiment, the safety detector can be of the light barrier type, and the control signal is modified by passing through the light barrier.

[0036] According to another variant embodiment, the safety detector can be of the cable actuation type, and the control signal is modified by the traction of the cable.

[0037] The present invention also relates to a safety detection system, including the safety detector as described above, an emergency stop device with two redundant contacts, and a start-up loop. The system is characterized in that:

[0038] - The start-up circuit is connected between the first control output and the second control output of the safety detector;

[0039] - The first redundant contact of the emergency stop device is connected between the first control input and the first control output, and the second redundant contact of the emergency stop device is connected between the second control input and the second control output.

[0040] According to a specific embodiment, the start-up circuit includes a start button.

[0041] According to another specific embodiment, the start-up circuit includes two normally closed contacts of two contactors for controlling the facility to be controlled.

[0042] The present invention also relates to a control method implemented in a safety detector employed in a safety detection system as defined above, the method including a first test sequence and / or a second test sequence, the first test sequence including the following steps:

[0043] - Disable the first control output of the detector;

[0044] - Test the state of the start-up circuit by enabling the second control output of the detector and by reading the state of the first control input of the detector;

[0045] The second test sequence includes the following steps:

[0046] - Disable the second control output of the detector;

[0047] - Test the state of the start-up circuit by enabling the first control output and by reading the state of the second control input of the detector.

[0048] According to a specific embodiment, the test step is carried out a number of times as long as the first control input is not enabled during the first test sequence, and / or as long as the second control input is not enabled during the second test sequence.

[0049] According to another specific embodiment, the method includes a start-up step by enabling the safety output and a step of re-enabling the first control output for the first test sequence.

[0050] According to another specific embodiment, the method includes a start-up step by enabling the safety output and a step of re-enabling the second control output for the second test sequence.

[0051] According to a specific embodiment, after the start-up step, the method includes steps for monitoring the first redundant contact of the emergency stop device between the first control input and the first control output and for monitoring the second redundant contact of the emergency stop device between the second control input and the second control output.

[0052] The invention also relates to the use of a safety detection system as defined above for monitoring the start-up of an electrical installation protected by a device, the device comprising a fixed part on which the sensor of the safety detector is fixed and a mobile part on which the transponder of the safety detector is fixed. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In the detailed description given below with reference to the drawings, other features and advantages will become apparent, in which:

[0054] Figure 1A The architecture of a conventional safety detector is schematically shown;

[0055] Figure 1B The architecture of a contactless safety detector having a sensor and a transponder is schematically shown;

[0056] Figures 2A to 2C The working principle of the contactless safety detector used in the protection of the installation is shown;

[0057] Figure 3 The conventional wiring architecture of the sensor of the contactless safety detector is shown;

[0058] Figure 4 The wiring principle of the safety detection system of the invention is shown;

[0059] Figure 5A and Figure 5B The operating principle of the system of the invention is shown;

[0060] Figure 6 is shown as Figure 5A an alternative or complementary test principle to the operating principle shown. DETAILED DESCRIPTION

[0061] In the following description, the OFF state is defined as the disabled state of the input terminal or the open state of the output terminal of the safety detector, and the ON state is defined as the enabled state of the input terminal or the closed state of the output terminal of the safety detector.

[0062] In a known manner, the ON state of the output terminal or the input terminal is defined by generating a non-zero electric potential on the electrical terminal associated with the output terminal or the input terminal, and the OFF state of the output terminal or the input terminal is defined by not generating an electric potential on the electrical terminal associated with the output terminal or the input terminal.

[0063] In a known manner, the input terminal or the output terminal is formed by one or more transistors, the input terminal is read by the control and processing unit, and the output terminal is controlled to open (OFF state) or close (ON state) by a signal from the control and processing unit.

[0064] The status of each output terminal can be indicated by an indicator light.

[0065] Reference Figure 1A , generally speaking, the safety detector 2 only includes eight electrical connection terminals, which will be described in detail below.

[0066] The detector 2 usually includes at least one module for detecting the control signal S_IN generated at the input terminal. Depending on the type of detector, the control signal S_IN can be modified by actuating or releasing the cable 10, by cutting the light beam of the light barrier 100, or by the absence or presence of the transponder 1 in the detection area of the sensor 2 when the sensor 2 is a contactless safety detector.

[0067] The detector 2 includes two redundant safety output terminals available at two safety output terminals of the detector, denoted as OSSD1 and OSSD2.

[0068] The detector includes two power supply terminals (0V and 24V) designed to be connected to an external power supply, and its internal circuit is connected to these two power supply terminals for power supply.

[0069] The detector includes a control input terminal I1 connected to the control input terminal and a potential control output terminal C1 available at the control output terminal.

[0070] The sensor includes a processing and control unit UC (control unit, UC), which schematically includes:

[0071] - A module IN for detecting the control signal S_IN;

[0072] - A module for reading the status of the control input terminal I1;

[0073] - A module for determining the operating state of the detector in consideration of the input terminal status (signals S_IN and I1) of the detector;

[0074] - A module for controlling the safety output terminals OSSD1, OSSD2 and the control output terminal C1 according to the determined operating state.

[0075] Reference Figure 1B , in the case of a contactless safety detector, the detector includes a sensor 3 and a transponder 1. The sensor 3 and the transponder 1 are manufactured in two separate and independent housings, and in this way can be respectively fixed to the fixed part and the moving part of the protection device (for example, Figures 2A to 2Cthe access device P of the dangerous machine M therein). Such a detector operates by using a contactless technology of the RFID (“Radio Frequency Identification”) type. The transponder 1 is assigned a unique code stored in its memory. The sensor 3 and the transponder 1 are paired. When the transponder 1 known to the sensor 3 appears in the detection area of the sensor 3, the control signal S_IN is modified. The detection module IN of the processing and control unit UC of the sensor 3 reads the code stored in the transponder 1.

[0076] In a non-limiting manner, the principle of the present invention is described hereinafter for a contactless type safety detector, but it is readily understood that this principle can be applied to all types of safety detectors, especially those already described above (light barriers, cable detectors, etc.). In fact, since the features of the present invention are mainly related to the test module present in the detector and the type of wiring of the detector, it can be understood that the control signal present at the input can be of any type.

[0077] As described above, the safety detector can have an automatic start or a monitored manual start. In the case of an automatic start, the detector includes two operating modes:

[0078] - RUN mode when the transponder 1 appears in the detection area of the sensor 3; after starting the “automatic test”, the safety output is automatically switched to the ON state;

[0079] - STOP mode when the transponder 1 is no longer in the detection area of the sensor 3; then the safety output is switched to the OFF state.

[0080] In the case of a monitored manual start, the system includes a start loop B_ST, which includes a start button SW associated with the detector, and the start button SW can take two different states, open (OFF) or closed (ON). Therefore, the detector 2 includes three operating modes:

[0081] - STOP mode when the transponder is no longer in the detection area of the sensor (device P is open) ( Figure 2A ); thus, the safety output is switched to the OFF state;

[0082] - START / RESTART mode when the transponder 1 appears in the detection area of the sensor 3 (device P is closed) but the start loop remains open (button SW is in the OFF state) ( Figure 2B ); thus, the safety output is in the OFF state;

[0083] - RUN mode when the transponder 1 appears in the detection area of the sensor 3 (device P is closed) ( Figure 2C) and when the latter detects that the start circuit is closed after the button SW enters the ON state, then it releases; then, the safety output is switched to the ON state.

[0084] In both configurations (automatic start or monitored manual), the detector 2 can include a fault detection module that is capable of keeping the output in the OFF state if the presence of a fault is detected. This module does not form part of the present invention and is therefore not described in the present application.

[0085] It can be seen that the present invention provides an advantage when the detector has a monitored manual start and thus when it is necessary to read the start circuit B_ST.

[0086] Furthermore, as described above, the detector can have autonomous operation, in other words, the contactors K1, K2 of the machine M to be controlled are directly connected to the safety output of the sensor without going through a safety logic block. In other words, once the safety output enters the ON state, the contactors controlling the machine are switched. Traditionally, the contactors K1, K2 are connected to the machine M in a redundant manner to ensure that the machine M stops even if one of the two contactors fails.

[0087] The present invention aims to provide a safety solution in which an emergency stop device AU is associated with a safety detector. The present invention mainly lies in arranging the detector to be able to manage this emergency stop function by itself. The present invention provides particular advantages when the detector is of the autonomous type.

[0088] As a reminder, the emergency stop device AU is a device that particularly includes a control button and at least two redundant NC (normally closed) type contacts AU_1, AU_2. It is designed to be connected to the circuit of the installation. In case of an anomaly, pressing the control button opens the two redundant contacts, allowing the electrical installation to stop. The application of redundancy is to detect any operating differences.

[0089] Figure 3 The wiring of the autonomous type safety detector 2 without an emergency stop device is shown. In Figure 3 there are:

[0090] - Two power supply terminals 0V, 24V, connected to an external power supply for applying a given voltage (here 24V) thereto;

[0091] - Two safety outputs, denoted as OSSD1 and OSSD2 ("Output Signal Switching Device"), each safety output is connected to the contactors (control coils KM1, KM2 of each contactor K1, K2) of the machine M to be controlled via two safety terminals;

[0092] - The first control input terminal I1 and the first control output terminal C1 are connected together via a start-up circuit B_ST, which includes a start button SW and the normally closed contacts K11, K12 of two contactors.

[0093] As described above, in this case, the detector 2 only includes two free terminals B (in other words, not connected to the input or output terminals of the detector), which theoretically is not sufficient to connect the two redundant contacts AU_1, AU_2 of the emergency stop device AU to them.

[0094] Figure 4 The wiring principle of a system including an emergency stop device AU with two redundant contacts, a safety detector 20 according to the present invention, and a start-up circuit B_ST is shown. According to this wiring principle, the two free terminals are used for the second control input terminal I2 and the second control output terminal C2 in the detector 20. Therefore, in Figure 4 there is:

[0095] - Two power supply terminals 0V, 24V, connected to an external power supply for applying a given voltage (here 24V) to it;

[0096] - Two safety output terminals OSSD1 and OSSD2, each of which is connected via two safety output terminals to independent contactors (control coils KM1, KM2) of the machine to be controlled; the two contactors K1, K2 are associated in a redundant manner for controlling the machine;

[0097] - A start-up circuit B_ST connected between the first control output terminal C1 and the second control output terminal C2;

[0098] - The first redundant contact AU_1 of the emergency stop device connected between the first control input terminal I1 and the first control output terminal C1, and the second redundant contact AU_2 of the emergency stop device connected between the second control input terminal I2 and the second control output terminal C2.

[0099] In this specific wiring configuration, in the control and processing unit UC of the detector, a specific test software module is added to the above-mentioned other software modules. This test module is designed to manage the addition of the emergency stop device AU while protecting the monitoring of the start-up circuit B_ST.

[0100] Advantageously, when the detector is in the START / RESTART mode, this test module is advantageously run by the control and processing unit UC. In this case, referring to Figure 5A and Figure 5B , the test module performs the following operation sequence:

[0101] Figure 5A

[0102] - The test module disables the first control output C1 and then enters the OFF state;

[0103] - The test module tests the status of the start circuit B_ST ( Figure 5A the path indicated by the darker line in) by switching the second control output C2 to the ON state and simultaneously reading the status of the first control input I1;

[0104] - When the start button switch is pressed, the first control input I1 enters the ON state, which means that the start circuit B_ST is closed and the first redundant contact AU_ is also closed.

[0105] Figure 5B

[0106] - The control and processing unit UC controls the detector to be switched to the RUN mode;

[0107] - The two safety outputs OSSD1 and OSSD2 are switched to the ON state, and the first control output C1 is switched back to the ON state;

[0108] - The status of the two redundant contacts AU_1 and AU_2 of the emergency stop device AU is monitored by the control and processing unit UC respectively between the first control input I1 and the first control output C1 of the sensor 30 and between the second control input I2 and the second control output C2 (by Figure 5B the path indicated by the darker line in).

[0109] Reference Figure 6 and, as an alternative or supplement to the sequence described in Figure 5A the test module can also be configured to test the start circuit between the first control output C1 and the second control input I2. In this case, the second control output C2 is disabled before the test and then re-enabled after the test.

[0110] It should be noted that a short-circuit test can also be performed between the two control outputs C2 and C1. As long as the test is positive (a short circuit between the two outputs), starting is not possible.

[0111] As a supplement, the second redundant contact AU_2 can also be tested by enabling the control output C2 and by monitoring the status of the second control input I2. If the path between C2 and I2 is closed, this means that the redundant contact AU_2 is indeed closed.

[0112] During the monitoring of the start circuit, once the start button SW is released, a possible short circuit on the start button SW can also be detected.

[0113] By means of a specific wiring configuration and adding a specific test module in the control and processing unit of the detector, it is possible to add an emergency stop function to the system while using a detector that includes only eight connection terminals.

[0114] The present invention provides a number of advantages, including:

[0115] - A solution that can simply implement the addition of an emergency stop function in a safety detection system;

[0116] - A solution that allows the use of safety logic blocks to be cancelled, where the function for managing the emergency stop is implemented by the detector;

[0117] - A solution that allows the system to remain within the initial size, where the detector has only eight terminals.

Claims

1. A safety detector (20), comprising a detection module (IN) configured to read a control signal (S_IN) at an input end, the safety detector comprising two power supply terminals, a first control input end (I1) and a first control output end (C1), a first safety output end (OSSD1) and a second safety output end (OSSD2), and a first free terminal and a second free terminal, characterized in that Comprising: - A second control input (I2) connected to the first free terminal and a second control output (C2) connected to the second free terminal, - A test module configured to apply a first test sequence and / or a second test sequence. The first test sequence includes disabling the first control output (C1) and testing the start-up loop (B_ST) connected between the second control output (C2) and the first control input (I1). The second test sequence includes disabling the second control output (C2) and testing the start-up loop (B_ST) connected between the first control output (C1) and the second control input (I2).

2. The safety detector according to claim 1, characterized in that, The test module is configured to execute a third test sequence, which includes enabling the second control output (C2) and reading the state of the second control input (I2).

3. The safety detector according to any one of claims 1 and 2, characterized in that, The test module is configured to execute a fourth test sequence, which includes reading the state of the first control output (C1) and the state of the second control output (C2).

4. The safety detector according to any one of claims 1 and 2, characterized in that, The safety detector includes a control and processing unit configured to run the test module.

5. The safety detector according to claim 4, characterized in that, The control and processing unit is configured to run: - A module for reading the state of each control input (I1, I2); - A module for determining the operating state in consideration of the state of the control inputs of the safety detector; - One or more modules for controlling the safety outputs (OSSD1, OSSD2) of the safety detector and the control outputs (C1, C2) of the safety detector according to the determined operating state.

6. The safety detector according to any one of claims 1 and 2, characterized in that It is contactless and includes: - A sensor (30) and a transponder (1) paired with the sensor (30), - When the transponder appears in the detection area of the sensor (30), the control signal (S_IN) is modified.

7. The safety detector according to any one of claims 1 and 2, characterized in that, It is of the light barrier type (100) and is characterized in that the control signal (S_IN) is modified by passing through the light barrier.

8. The safety detector according to any one of claims 1 and 2, characterized in that, The safety detector is actuated by a cable (10) and is characterized in that the control signal (S_IN) is modified by the traction of the cable.

9. A safety detection system, comprising the safety detector (20) according to any one of claims 1 to 8, an emergency stop device (AU) having two redundant contacts (AU_1, AU_2), and a start-up loop (B_ST), characterized in that: - The start-up loop (B_ST) is connected between the first control output (C1) and the second control output (C2) of the safety detector; - The first redundant contact (AU_1) of the emergency stop device is connected between the first control input (I1) and the first control output (C1), and the second redundant contact (AU_2) of the emergency stop device is connected between the second control input (I2) and the second control output (C2).

10. The system according to claim 9, characterized in that, The start-up loop (B_ST) includes a start button (SW).

11. The system according to claim 10, wherein, The start-up loop (B_ST) includes two normally closed contacts (K11, K12) of two control contactors (K1, K2) of the facility to be controlled.

12. A control method implemented in a safety detector employed in the safety detection system according to any one of claims 9 to 11, characterized in that Including a first test sequence and / or a second test sequence, the first test sequence comprising the following steps: - Disable the first control output (C1) of the safety detector (20); - Test the state of the start-up circuit (B_ST) by enabling the second control output (C2) and by reading the state of the first control input (I1) of the safety detector (20); The second test sequence comprises the following steps: - Disable the second control output (C2) of the safety detector (20); - Test the state of the start-up circuit (B_ST) by enabling the first control output (C1) and by reading the state of the second control input (I2) of the safety detector (20).

13. The method according to claim 12, wherein The test steps are carried out a number of times as long as the first control input (I1) is not enabled during the first test sequence and / or as long as the second control input (I2) is not enabled during the second test sequence.

14. The method according to any one of claims 12 and 13, characterized in that Including the step of starting by enabling the safety outputs (OSSD1, OSSD2), and the step of re-enabling the first control output (C1) for the first test sequence.

15. The method according to any one of claims 12 and 13, characterized in that Including the step of starting by enabling the safety outputs (OSSD1, OSSD2), and the step of re-enabling the second control output (C2) for the second test sequence.

16. The method according to any one of claims 12 and 13, characterized in that Including, after the starting step, the step of monitoring the first redundant contact (AU_1) of the emergency stop device (AU) between the first control input (I1) and the first control output (C1) and the second redundant contact (AU_2) of the emergency stop device (AU) between the second control input (I2) and the second control output (C2).

17. Use of a safety detection system according to any one of claims 9 to 11 for monitoring the start-up of an electrical installation for the protection of a device having a fixed part to which a sensor (30) including a safety detector (20) is fixed and a moving part to which a transponder (1) of the safety detector (20) is fixed.

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