SAFETY DETECTOR AND SAFETY DETECTION SYSTEM INCLUDING SAID SAFETY DETECTOR

Abstract

A safety detector including a detection module configured for reading a control signal at the input, the detector including two supply 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 including: a second control input connected to the first free terminal and a second control output connected to the second free terminal, and a test module configured for notably applying a first test sequence including a disabling of the first control output and a test of a start loop connected between the second control output and the first control input.

Claims

1. A safety detector comprising a detection module configured for reading a control signal at the input, said detector comprising two supply 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 safety detector comprising: a second control input connected to the first free terminal and a second control output connected to the second free terminal, a test module configured for applying a first test sequence comprising a disabling of the first control output and a test of a start loop connected between the second control output and the first control input and/or a second test sequence comprising a disabling of the second control output and a test of a start loop connected between the first control output and the second control input.

2. The safety detector according to claim 1, wherein the test module is configured for carrying out a third test sequence comprising an enabling of the second control output and a read of the status of the second control input.

3. The safety detector according to claim 1, wherein the test module is configured for carrying out a fourth test sequence comprising a read of the status of the first control output and of the status of the second control output.

4. The safety detector according to claim 1, wherein the safety detector comprises a control and processing unit configured for running said test module.

5. The safety detector according to claim 4, wherein the control and processing unit is configured for running: a module for reading the status of each control input; a module for determining an operational state taking into account the status of the control inputs of the safety detector; one or more modules for controlling the safety outputs of the safety detector and the control outputs of the safety detector, according to the determined operational state.

6. The safety detector according to claim 1, wherein the safety detector is of the contactless type and wherein the safety detector comprises: a sensor and a transponder paired to said sensor, the control signal being modified when said transponder is present in a detection area of the sensor.

7. The safety detector according to claim 1, wherein the safety detector is of the light barrier type and wherein the control signal is modified by passing through said light barrier.

8. The safety detector according to claim 1, wherein the safety detector is of the actuation by cable type and wherein the control signal is modified by traction of said cable.

9. A safety detection system, comprising a safety detector according to claim 1, an emergency stop device with two redundant contacts and a start loop, wherein: the start loop is connected between the first control output and the second control output of the safety detector; and a 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.

10. The system according to claim 9, wherein the start loop comprises a start push-button.

11. The system according to claim 10, wherein the start loop comprises two normally-closed contacts of two control contactors of an installation to be controlled.

12. A control method implemented in a safety detector employed in a safety detection system according to claim 9, the control method comprising a first test sequence comprising: disabling the first control output of the detector; and testing the status of the start loop by enabling the second control output and by reading the status of the first control input of the detector; and/or a second test sequence for comprising: disabling the second control output of the detector; and testing the status of the start loop by enabling the first control output and by reading the status of the second control input of the detector.

13. The method according to claim 12, wherein the testing is implemented several times for as long as the first control input has not been enabled during said first test sequence and/or for as long as the second control input has not been enabled during the second test sequence.

14. The method according to claim 12, further comprising starting by enabling safety outputs and re-enabling the first control output for the first test sequence.

15. The method according to claim 12, further comprising starting by enabling safety outputs and re-enabling the second control output for the second test sequence.

16. The method according to claim 14, further comprising, after said starting, monitoring the first redundant contact of the emergency stop device between the first control input and the first control output and monitoring the second redundant contact of the emergency stop device between the second control input and the second control output.

17. A method of using the safety detection system according to claim 9, the method comprising monitoring the start of an electrical installation protected by a device comprising a fixed part onto which a sensor of the safety detector is fixed and a mobile part onto which a transponder of the safety detector is fixed.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0054] Other features and advantages will become apparent in the detailed description that follows presented with reference to the appended drawings, wherein:

[0055] FIG. 1A shows schematically the architecture of a conventional safety detector and FIG. 1B shows schematically the architecture of a contactless safety detector having a sensor and a transponder;

[0056] FIGS. 2A to 2C illustrate the principle of operation of a contactless safety detector employed in the protection of an installation;

[0057] FIG. 3 shows a conventional architecture for wiring of the sensor of a contactless safety detector;

[0058] FIG. 4 shows the principle of wiring of the safety detection system of the invention;

[0059] FIGS. 5A and 5B illustrate the principle of operation of the system of the invention;

[0060] FIG. 6 illustrates the principle of a test alternative or complementary to that illustrated by FIG. 5A.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT

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

[0062] In a known manner, the ON state of an output or of an input is defined by the creation of a non-zero electrical potential on an electrical terminal associated with the output or with the input and the OFF state of an output or of an input is defined by an absence of electrical potential on the electrical terminal associated with the output or with the input.

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

[0064] The status of each output may be indicated by an indicator lamp.

[0065] With reference to FIG. 1A, generally speaking, a safety detector 2 comprises only eight electrical connection terminals which will be detailed hereinbelow.

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

[0067] The detector 2 comprises two redundant safety outputs, referenced OSSD1 and OSSD2, available on two safety output terminals of the detector.

[0068] It comprises two electrical supply terminals (0V and 24V) designed to be connected to an external power supply and to which its internal circuits are connected in order to be supplied with electricity.

[0069] It comprises a control input I1 connected to a control input terminal and potentially a control output C1 available on a control output terminal.

[0070] The sensor comprises a processing and control unit UC comprising schematically: [0071] The module IN for detecting the control signal S_IN; [0072] A module for reading the status of the control input I1; [0073] A module for determining the operational state of the detector, taking into account the status of its inputs (signal S_IN and I1); [0074] A module for controlling the safety outputs OSSD1, OSSD2 and the control output C1, according to the determined operational state.

[0075] With reference to FIG. 1B, in the case of a safety detector of the contactless type, the detector comprises a sensor 3 and a transponder 1. The sensor 3 and the transponder 1 are fabricated in two separate and independent housings, in such a manner as to be fixable respectively onto a fixed part and onto a mobile part of a protection device (for example a means of access P to a dangerous machine M in FIGS. 2A to 2C). Such a detector operates by employing 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 by the sensor 3, is present 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 invention is described hereinbelow for a contactless safety detector, but it will readily be understood that it may be applied to all types of safety detectors, notably those already described hereinabove (light barrier, cable detector, etc.). Indeed, as the inventive features are mainly linked to the test module present in the detector and to the type of wiring of the detector, it will be understood that the control signal S_IN present at the input could be of any type.

[0077] As described hereinabove, the safety detector may have an automatic start or a monitored manual start. With automatic start, the detector comprises two modes of operation: [0078] RUN mode when the transponder 1 is present in the detection area of the sensor 3; the safety outputs are switched automatically to the ON state after start “auto-tests”; [0079] STOP mode when the transponder 1 is no longer in the detection area of the sensor 3; the safety outputs are then switched to the OFF state.

[0080] With monitored manual start, the system comprises a start loop B_ST comprising a start button SW associated with the detector, which can take two distinct states, open (OFF) or closed (ON). The detector 2 thus comprises three modes of operation: [0081] STOP mode (FIG. 2A) when the transponder is no longer in the detection area of the sensor (device P open); the safety outputs are therefore switched to the OFF state; [0082] START/RESTART mode (FIG. 2B) when the transponder 1 is present in the detection area (device P closed) of the sensor 3 but the start loop remains open (button SW in the OFF state); the safety outputs are therefore in the OFF state; [0083] RUN mode (FIG. 2C) when the transponder 1 is present in the detection area of the sensor 3 (device P closed) and when the latter detects the closing of the start loop after the button SW goes to the ON state, then its release; the safety outputs are then switched to the ON state.

[0084] In the two configurations (automatic start or monitored manual), the detector 2 may comprise a fault detection module able to hold the outputs in the OFF state if the presence of a fault is detected. This module does not form part of the invention and is not therefore described in the present application.

[0085] It will be seen that the invention offers an advantage when the detector has a monitored manual start and hence when a read of the start loop B_ST is required.

[0086] Furthermore, as described hereinabove, the detector may have autonomous operation, in other words the contactors K1, K2 of the machine M to be controlled are directly connected to the safety outputs of the sensor, without going via a safety logic block. In other words, as soon as the safety outputs go to the ON state, the contactors controlling the machine are switched. Conventionally, the contactors K1, K2 are connected to the machine M in a redundant manner so as to ensure the shutdown of the machine M, even in the case of a malfunction of one of the two contactors.

[0087] The invention aims to provide a safety solution wherein an emergency stop device AU is associated with a safety detector. The invention consists notably in arranging for the detector to be able to manage itself this emergency stop functionality. The invention offers a particular advantage when the detector is of the autonomous type.

[0088] As a reminder, an emergency stop device AU is a device which notably comprises a control button and at least two redundant contacts AU_1, AU_2 of the NC (Normally-Closed) type. It is designed to be connected to a circuit of the installation. In the case of an anomaly, pressing the control button opens the two redundant contacts, allowing the electrical installation to be stopped. The redundancy is applied in order to detect any operational discrepancy.

[0089] FIG. 3 shows the wiring of a safety detector 2 of the autonomous type, without an emergency stop device. In this FIG. 3, there are thus: [0090] The two supply terminals 0V, 24V connected to an external power source for applying a given voltage to it (here 24V); [0091] The two safety outputs, denoted OSSD1 and OSSD2 (for “Output Signal Switching Device”) each connected via the two safety terminals to a contactor (control coils KM1, KM2 of each contactor K1, K2) of the machine M to be controlled; [0092] A first control input I1 and a first control output C1 connected together via a start loop B_ST comprising a start push-button SW and the normally-closed contacts K11, K12 of the two contactors.

[0093] As described hereinabove, in this scenario, the detector 2 only then comprises two free terminals B (in other words not connected to an input or an output of the detector), which is in theory insufficient to connect to them the two redundant contacts AU_1, AU_2 of the emergency stop device AU.

[0094] FIG. 4 shows the wiring principle of the system comprising the emergency stop device AU with two redundant contacts, a safety detector 20 according to the invention and the start loop B_ST. According to this wiring principle, the two free terminals are used on a second control input 12 and a second control output C2 present in the detector 20. In FIG. 4, there are thus: [0095] The two supply terminals 0V, 24V which are connected to an external power source for applying a given voltage to it (here 24V); [0096] The two safety outputs OSSD1 and OSSD2 which are each connected via the two safety output terminals to a separate contactor (control coils KM1, KM2) of the machine to be controlled; the two contactors K1, K2 are associated in a redundant manner for the control of the machine; [0097] The start loop B_ST which is connected between the first control output C1 and the second control output C2; [0098] The first redundant contact AU_1 of the emergency stop device which 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 which is connected between the second control input 12 and the second control output C2.

[0099] In this particular wiring configuration, a specific test software module is added to the other software modules described hereinabove, in the control and processing unit UC of the detector. This test module is designed to manage the addition of the emergency stop device AU, while at the same time conserving the monitoring of the start loop B_ST.

[0100] Advantageously, this test module is advantageously run by the control and processing unit UC when the detector is in the START/RESTART mode. In this situation, with reference to FIGS. 5A and 5B, the following sequence of operations is executed by the test module:

[0101] FIG. 5A [0102] The test module disables the first control output C1, which then goes to the OFF state; [0103] The test module tests the status of the start loop B_ST by switching the second control output C2 to the ON state and while reading the status of the first control input I1 (paths indicated by darker lines in FIG. 5A); [0104] When the start push-button SW is pressed, the first control input I1 goes to the ON state, meaning that the start loop B_ST is closed but also that the first redundant contact AU_ is also closed.

[0105] FIG. 5B [0106] The control and processing unit UC controls the switching of the detector into RUN mode; [0107] The two safety outputs OSSD1, OSSD2 are switched into the ON state and the first control output C1 is switched back into the ON state; [0108] The states of the two redundant contacts AU_1, AU_2 of the emergency stop device AU are monitored by the control and processing unit UC, respectively between the first control input I1 and the first control output C1 and between the second control input 12 and the second control output C2 of the sensor 30 (paths indicated by darker lines in FIG. 5B).

[0109] With reference to FIG. 6, as an alternative or as a complement to the sequence described in conjunction with FIG. 5A, the test module may also be configured for testing the start loop between the first control output C1 and the second control input 12. In this case, the second control output C2 is disabled prior to the test then re-enabled after the test.

[0110] It should be noted that a short-circuit test may also be implemented between the two control outputs C1, C2. For as long as the test is positive (short-circuit between the two outputs), the start is impossible.

[0111] As a complement, it is also possible to test the second redundant contact AU_2 by enabling the control output C2 and by monitoring the status of the second control input 12. If the path between C2 and 12 is closed, this means that the redundant contact AU_2 is indeed closed.

[0112] During the monitoring of the start loop, it is also possible to detect a possible short-circuit on the start button SW, once the latter has been released.

[0113] By the particular wiring configuration and the addition of a particular test module in the control and processing unit of the detector, it is possible to add the emergency stop functionality to the system while employing a detector which only comprises eight connection terminals.

[0114] The invention offers numerous advantages, amongst which are: [0115] A solution that is simple to implement for adding an emergency stop function in a safety detection system; [0116] A solution allowing the use of a safety logic block to be obviated, the function for management of the emergency stop being implemented by the detector; [0117] A solution which allows the system to remain within the initial size with only eight terminals of the detector.