Safety device, system and technological process

Abstract

The safety device comprises a safety switch and an actuator which are designed to be associated with the movable guard and interact with each other when the movable guard is opened and closed. The safety switch comprises a switching device designed to switch between an active state and an inactive state, a locking mechanism for locking the actuator in contact with the safety switch, a control unit connected to the locking mechanism, and the switching device for controlling the locking mechanism. The safety switch also includes a primary reset member for transmitting a primary reset signal to the control unit.

Description

Technical Field

[0001] The present invention relates to a safety device suitable for industrial automation, in particular for controlling the entrance inside the safety perimeter of a machine or industrial facility. The present invention also relates to a safety system including the above safety device and its operation process. Background Art

[0002] In the field of industrial automation, it is known to enclose a machine or system characterized by hazardous operations with a mechanical barrier in order to prevent an operator from coming into contact with the machine during its operation.

[0003] Also known, occasionally need to allow operators to enter the closed machine for processing or maintenance needs, or other similar needs. For this reason, usually, the mechanical barrier of the closed machine is equipped with a movable guard, such as a door or hatch, which allows the operator to enter the closed area and operate on the machine.

[0004] The movable guard is usually associated with a safety switch, also called an "interlock device", which detects its state, i.e. whether the movable guard is open, closed or locked, and safely signals this state to the control device. The control device, such as a PLC or a safety module, thus controls the power supply to the machine depending on the state of the movable guard. Usually, the control device allows the machine to be started only when it detects that the movable guard is closed and locked.

[0005] However, in some cases, in order to allow the machine to be restarted, the movable guard must be closed and locked, and the operator must signal that he has actually left the enclosed area.

[0006] To allow this, some known systems, such as the one described in EP3922898, include, in addition to the safety switch, a button panel independent of it and provided with a reset (or confirmation) button and a control unit. In these cases, the control unit of the button panel is connected to the safety switch to control its operation and receive information related to the state of the movable guard. In addition, the control unit of the button panel is also connected to the control device, PLC, to transmit to it a safety signal allowing the machine to be restarted. Specifically, the safety signal is emitted when the control unit detects through the safety switch that the movable guard is closed and locked and when its reset button is pressed.

[0007] Despite its applications, this solution has some disadvantages.

[0008] The first disadvantage is that the control unit of the pushbutton panel should manage the signals safely transmitted by the safety switch. For this purpose, the control unit of the pushbutton panel must be equipped with a safety architecture, such as redundancy with two channels, which increases its production and installation costs.

[0009] Another disadvantage is that, in order to prepare the known system, it is necessary to connect the pushbutton panel to the safety switches and controls. This involves a very laborious, expensive and often time-consuming installation. Moreover, such an installation requires many manual steps that are prone to human errors and can compromise the safety of the machine operator. Summary of the invention

[0010] The object of the present invention is to achieve an economical and compact safety device which at the same time allows signaling that the movable guard is closed and locked and that the operator has left the enclosed area.

[0011] Another object of the invention is to achieve a safety device that can be installed simply and in a shorter time than the known solutions.

[0012] Another object of the invention is to realize a safety device that is simple to use for an operator and that makes the operation for restarting the machine simpler. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 and Figure 3 is a schematic diagram of a safety device according to various embodiments of the present invention under use conditions;

[0014] Figure 2 and Figure 4 They are Figure 1 and Figure 3 A simplified representation of the electrical connection diagram of the safety device;

[0015] Figure 5 and 6 They are Figure 1 and 3 A simplified representation of a circuit diagram of a part of a safety device;

[0016] Figure 7 and Figure 8 is an axonometric view of a portion of the safety device of the present invention according to two embodiments;

[0017] Fig. 9 and 10 yes Figure 7 and 8 A schematic cross-sectional view of a portion of a safety device in;

[0018] Figures 11 to 14 is a flow chart of the process according to the present invention.

[0019] Best Mode for Carrying Out the Invention

[0020] refer to Figure 1 and 4, a safety device 1 according to the invention comprises a safety switch 10 designed to be associated with a movable guard 11 of a mechanical barrier 12 to protect a machine or industrial installation 13, hereinafter simply referred to as machine 13.

[0021] As an example, the movable guard 11 can be any type of door, such as a hinged, sliding or other type of door, a gate, a gate, a cover, a hood, a cap, a movable shutter or more. The movable guard 11 includes a fixed part F ( Figure 7 and 8 ), such as a frame, and a movable part M, which can be moved relative to the fixed part F between an open position and a closed position, wherein the open position allows an operator to at least partially enter the area defined by the mechanical barrier 12 and the closed position does not allow the operator to enter the area defined by the mechanical barrier 12.

[0022] The safety device 1 further comprises an actuator 15, which is designed to interact with the safety switch 10 at the opening and closing of the movable guard 11. Specifically, the safety switch 10 is adapted to be fixed between one of the fixed part F and the movable part M and the actuator 15 is adapted to be fixed between the other of the fixed part F and the movable part M.

[0023] In the example given here, the safety switch 10 is fixed to the fixed part F and the actuator 15 is fixed to the movable part M.

[0024] The safety switch 10 comprises a housing 16 which contains a control unit 17 of electronic type ( Figure 5 , 6, 9 and 10) and the switching device 19, controlled by the control unit 17, can be switched between an active state and an inactive state, which can be distinguished from each other and at the communication interface 20.

[0025] In this case, the switching device 19 comprises one or more safety outputs of the OSSD type, each of which can be switched into at least one active state and one inactive state which can be distinguished from one another.

[0026] As an example, a safety output in an active state transmits a signal and becomes a logical state equal to "1" or "on", while in an inactive state it does not transmit any signal and becomes a logical state equal to "0" or "off".

[0027] More preferably, the switching device 19 comprises at least two independent safety outputs of the OSSD type.

[0028] The control unit 17 and the switch device 19 may be arranged on the same PCB, or they may be arranged in separate PCBs that are physically separated and electrically connected to each other.

[0029] In other possible embodiments, the switching device 19 may also be of other known types and include electronic contacts of mechanical, electromechanical type, relays or any other electrical, electronic or electromechanical elements, suitable for selectively moving from an active state that allows signal transmission and an inactive state that does not allow signal transmission.

[0030] Furthermore, the communication interface 20 is designed to send one or more signals associated with the state of the switching device 19 to one or more devices outside the safety switch 10. Specifically, the communication interface 20 is designed to send at least one signal encoding the state of the switching device 19.

[0031] For example, the communication interface 20 may comprise one or more connectors or a communication bus, such as of the IO-Link or ProfiSafe or ProfiNet type, or it may be of the wireless type or any combination thereof.

[0032] In use, the communication interface 20 may be connected or linked to the control device 101 ( Figure 2 and 4 6), the control device 101 is suitable for controlling the machine 13 based on the signal associated with the state of the switching device 19. The control device 101 may include a PLC or a safety module, or a current contactor or similar device or the same type or any combination thereof connected to the power supply of the machine 13. For example, if the state of the switching device 19 is inactive, the control device 101 does not allow the machine 13 to start.

[0033] The safety switch 10 also includes a locking mechanism 25 ( Figure 5 , 6 and 9, 10). Specifically, the locking mechanism 25 is controlled by the control unit 17 and is designed to rotate between a locked state and an unlocked state, in which the locking mechanism 25 keeps the actuator 15 at least in contact with the safety switch 10, and in which the actuator 15 is not held relative to the safety switch 10 and can be moved away from the safety switch 10. For example, in the locked state, the movable guard 11 cannot be opened, and in the unlocked state, the movable guard 11 can be opened.

[0034] In this example, refer to Figures 7 to 10 , the safety switch 10 further comprises a seat 21 for receiving at least a portion of the actuator 15. Specifically, in these cases, the actuator 15 comprises a drive pin 22, and the seat 21 is shaped to accommodate at least a portion of the drive pin 22 inside it.

[0035] In addition, the locking mechanism 25 is designed to selectively lock the drive pin 22 in the seat 21. Specifically, the locking mechanism 25 is arranged in the housing 16 and includes a locking pin 26 and a moving member 27 controlled by the control unit 17 and designed to move the locking pin 26 between a locked position and an unlocked position, in which the locking pin 26 protrudes in the seat 21, and in which the locking pin 26 is retracted toward the inside of the housing 16 relative to the locked position. The moving member 27 includes, for example, an electromagnet controlled by the control unit 17, but may include any other member suitable for moving the locking pin 26 between the locked position and the unlocked position, such as a motor, a pneumatic member or other things.

[0036] The locking pin 26 and the drive pin 22 are at least partially shaped to complement each other so that the drive pin 22 cannot be withdrawn from the seat 21 when the locking pin 26 is in the locking position, and the drive pin 22 can be withdrawn from the seat 21 when the locking pin 26 is in the unlocking position.

[0037] In addition, the safety switch 10 also includes a sensor device 29 for sensing the position of the locking pin 26, which is connected to the control unit 17 to communicate with the latter at least whether the locking pin 26 is in the locked position. As an example, the sensor device 29 includes one or more photoelectric barriers, each of which is placed to be intercepted by a corresponding protrusion associated with the locking pin 26 when the latter is in the locked position. It will be understood by those skilled in the art that the sensor device 29 can also be of any other known type, such as mechanical, electromechanical, electronic, magnetic and more.

[0038] It should be noted that the seat 21 can be directly on the housing 16 ( Figure 7 and 9 ) or fixed to the head 23 ( Figure 8 and 10 ), for example at one end thereof.

[0039] In other embodiments not shown in the figures, the safety switch 10 may not have a seat for the actuator 15, and the locking mechanism 25 may be of magnetic type and include an electromagnet controlled by the control unit 17. In these embodiments, the actuator 15 includes a ferromagnetic element suitable for interacting with the electromagnet. In these cases, the control unit 17 is designed to move the locking mechanism 25 to a locked state by activating the electromagnet so as to block the ferromagnetic element from contacting the safety switch 10 and to move the locking mechanism to an unlocked state by deactivating the electromagnet, thereby allowing the ferromagnetic element to be away from the safety switch 10.

[0040] Optionally, the safety switch 10 and the actuator 15 include respective communication devices 30, 31, which are designed to interact remotely when the actuator 15 approaches the safety switch 10 and sends a proximity signal P to the control unit 17. Specifically, the safety switch 10 includes a first communication device 30, and the actuator 15 includes a second communication device 31 designed to interact remotely with the first communication device 30 when approaching it. The first communication device 30 is connected to the control unit 17 and is designed to transmit the proximity signal P indicating that the actuator 15 is close to the safety switch 10.

[0041] As an example, the first communication means 30 is an RFID antenna and the second communication means 31 is an RFID transponder. In this case, the RFID antenna is adapted to transmit a signal adapted to excite the RFID transponder when the latter is close to the RFID antenna. The RFID transponder, when excited by the RFID antenna, is also adapted to transmit a response signal encoding an identification code of the actuator 15 to the RFID antenna. The RFID antenna is designed to receive the response signal transmitted by the transponder and to transmit a proximity signal P associated with the identification code of the actuator 15 to the control unit 17. This allows the control unit 17 to verify that only the correct actuator 15 interacts with the safety switch 10.

[0042] Furthermore, the proximity signal P allows the control unit 17 to detect that the movable guard 11 is closed. For example, when the locking mechanism is in an unlocked state and the control unit 17 receives the proximity signal P, the movable guard 11 is detected as closed but not locked.

[0043] The safety switch 10 further comprises interaction means 36, 37 connected to the control unit 17 for transmitting electrical signals thereto in response to interaction with the user.

[0044] The interaction device comprises a master reset member 36 connected to the control unit 17, emitting a master reset signal R1 in response to interaction with the user. As an example, the master reset member 36 may be any member suitable for being processed by the user to emit an electrical or electronic signal, such as a button, a joystick, a knob, a key or a screen touch-sensitive or similar device. Preferably, the master reset member 36 is fixed directly on the housing 16 of the safety switch 10. Even more preferably, the master reset member 36 is a button fixed directly on the housing 16 of the safety switch 10. In this case, in a preferred embodiment, the master reset member 36 is a button fixed directly on the housing 16 of the safety switch 10, which is designed to send a master reset signal R1 to the control unit 17 in response to pressure released by the user. In this way, the physical separation between the safety switch and the master reset device 36 is removed. In addition, since it is not enough for the user to press the button to emit the master reset R1, but the pressure must follow the release of the button, so the safety is improved.

[0045] Optionally, the interaction means for interacting with the user may further include a blocking member 37, which is also connected to the control unit 17 and is designed to send a locking signal B thereto in response to interaction with the user. In this case, the control unit 17 is also configured to recognize the locking signal B and command the locking mechanism 25 to move it to a locked state.

[0046] Preferably, the blocking member 37 is directly fixed to the housing 16 of the safety switch 10 .

[0047] However, the scope of the present invention also encompasses those embodiments in which the safety switch 10 is connected to an external locking member and connected to the safety switch 10 via the communication interface 20 for transmitting the locking signal.

[0048] According to one aspect of the invention, the control unit 17 is designed to move the switching device 19 to the active state when it receives or has received the master reset signal R1 , and the actuator 15 is locked in contact with the safety switch 10 .

[0049] In the present example, the control unit 17 is designed to move the switching device 19 to the active state when it receives or has received the master reset signal R1 , and the actuator 15 is locked in the seat 21 by the locking mechanism 25 .

[0050] Advantageously, the safety device 1 of the invention allows a high degree of safety to be achieved while being cost-effective, compact and easy to install. In fact, the integration of the master reset member 36 directly into the safety switch 10, on the one hand, saves space, since no further human-machine interface separate from the safety switch 10 must be associated with the movable guard 11, and on the other hand also allows a reduction in installation time, since the safety switch 10 already equipped with the master reset member 36 must only be connected to the control device 101. This also allows a reduction in the number of operations requested for installing the safety device 1, and therefore also in the probability of human error. Moreover, the use of the safety device 1 is thus made easier for the operator, since there is no physical separation between the safety switch 10 and the master reset device 36.

[0051] In the first embodiment, the control unit 17 is designed to move the switching device 19 to the active state when the actuator 15 is locked in contact with the safety switch 10 and simultaneously receives the master reset signal R1 .

[0052] For example, when the actuator 15 is inserted into and locked by the locking mechanism 25 into the seat 21 and simultaneously receives the master reset signal R1, the control unit 17 is adapted to move the switch device 19 to the active state. In these embodiments, the locking mechanism 25 may be moved from the unlocked state to the locked state before transmitting the master reset signal R1, for example, the control unit 17 receives the proximity signal P automatically or in response to the locking signal B.

[0053] In another embodiment, when the actuator 15 is locked in contact with the safety switch 10 after receiving the master reset signal R1 , the control unit 17 is designed to move the switching device 19 to the active state.

[0054] For example, the control unit 17 is designed to move the switch device 19 to the active state when the actuator 15 is locked in the seat 21 by the locking mechanism 25 after receiving the master reset signal R1. In these embodiments, the locking mechanism 25 switches from the unlocked state to the locked state in response to the locking signal B emitted by the blocking member 37.

[0055] In some embodiments, the safety device 1 further comprises an auxiliary reset device 40, which is different from and separate from the safety switch 10 and can be operated by an operator. The auxiliary reset device 40 is, for example, a button on a button panel that is separate and different from the safety switch 10. Preferably, in use, the auxiliary reset device 40 is arranged within the mechanical barrier 12.

[0056] The second resetting device 40 is connected to the control unit 17 of the safety switch 10 and is designed to send an auxiliary reset signal R2 thereto in response to an interaction with an operator.

[0057] In these cases, the control unit 17 is designed to move the switching device 19 to the active state when it receives or has received the primary R1 and auxiliary R2 reset signals, and the actuator 15 remains in contact with the safety switch 10 .

[0058] Preferably, the control unit 17 is designed to move the switching device 19 to the active state only when the auxiliary reset signal R2 is received before the main reset signal R1. In addition, the control unit 17 can also be designed to detect the time interval t that has passed between the reception of the auxiliary reset signal R2 and the main reset signal R1, and compare the time interval t with a predetermined threshold value t1. In these cases, when the time interval t is less than the predetermined threshold value t1 and the actuator 15 is locked in contact with the safety switch 10 through the locking mechanism 25, the control unit 17 is designed to move the switching device 19 to the active state.

[0059] The invention also relates to a safety system 100 comprising a machine 13 at least partially surrounded by a mechanical protection barrier 12 having a movable guard 11 provided with a fixed part F and a movable part M. The safety system 100 also comprises a safety device 1 according to the invention associated with the movable guard 11 and a control device 101 connected to the safety device 1 and designed to allow or not allow the operation of the machine 13 as a function of the state of the switching device 19.

[0060] The safety switch 10 is connected to a control device 101 via a communication interface 20 which is designed to transmit control signals associated with the state of the switching device 19 to the control device 101 .

[0061] The control device 101 is designed to allow or not allow operation of the machine 13 as a function of a signal associated with the state of the switching device 19 emitted by the safety switch 10. Preferably, the control device 101 is designed to allow operation of the machine 13 if the switching device 19 is active.

[0062] refer to Figures 11 to 14 The invention also relates to a safety process for controlling access to a hazardous area protected by the safety device 1 described above.

[0063] The process flow includes a closing step S1 of the movable guard 11, in which the actuator 15 moves close to the safety switch 10 and interacts therewith, and a locking step S2, in which the locking mechanism 25 changes to the locked state by locking the actuator 15 in contact with the safety switch 10.

[0064] During the closing step S1 , the control unit 17 receives a proximity signal P generated in response to the recognition of the second communication device 31 by the first communication device 30 .

[0065] In the locking step S2, the control unit 17 controls the locking mechanism 25 to move it from the unlocked state to the locked state, wherein the locking mechanism 25 locks the actuator 15 in contact with the safety switch 10. The locking step S2 can be triggered by operating the blocking member 37 integrated in the safety switch 10 or via any other blocking member external to the safety switch 10, or it can occur automatically.

[0066] The process flow further includes a master reset step S3 , in which the master reset component 36 transmits a master reset signal R1 to the control unit 17 .

[0067] Furthermore, the method provides a switching step S4, wherein the switching device 19 is turned to the active state. During the switching step S4, the control unit 17 controls the switching device 19 to move it to the active state.

[0068] It should be noted that the switching step S4 occurs only after the main resetting step R1 and the locking step S2.

[0069] Specifically, in order to move the switching device 19 to the active state, the control unit 17 must at least receive the master reset signal R1 and detect that the actuator 15 is locked in contact with the safety switch 10 by the locking mechanism 25 .

[0070] Without departing from the scope of protection of the present invention, the locking step S2 may be performed in the master reset step S3 ( Fig.11 or 13) before or after ( Fig.12 or 14) occurs.

[0071] refer to Fig.13 and Fig.14 In some embodiments, the process flow of the present invention further provides an auxiliary reset step S5, wherein the auxiliary reset component 40 transmits an auxiliary reset signal R2 to the control unit 17. In these embodiments, the auxiliary reset step S5 occurs before the locking step S2 and the main reset step S3.

[0072] Furthermore, in these embodiments, the method provides a processing step S6 after the main reset step S3, in which the control unit 17 detects the time interval t that has passed between receiving the auxiliary reset signal R2 and the main reset signal R1, and compares it with a predetermined threshold value t1. Therefore, only when the time interval t is less than the predetermined threshold value t1 and the locking step S2 is performed, the control unit 17 performs a switching step S4, in which the control unit 17 controls the switching devices 19 to move them to an active state. On the contrary, if the time that has passed between receiving the auxiliary reset signal R2 and the main reset signal R1 is greater than the predetermined threshold value, the control unit 17 keeps the switching devices in an inactive state.

Claims

1. A safety device comprising a safety switch (10) and an actuator (15) designed to be associated with a movable guard (11) and to interact with each other when the movable guard (11) is opened and closed, wherein the safety switch (10) comprises: - a switching device (19) designed to switch between an active state and an inactive state; a locking mechanism (25) designed to switch between a locked state and an unlocked state, in which the locking mechanism locks the actuator (15) in contact with the safety switch (10), and an unlocked state, in which the locking mechanism allows the actuator (15) to be removed from the safety switch (10); - a control unit (17) connected to the locking mechanism (25) to detect the state thereof and the switching device (19) and to control the switching device (19); The safety switch (17) further comprises a master reset device (36) connected to the control unit (17), the master reset device (36) being adapted to be operated by an operator and being designed to transmit a master reset signal (R1) to the control unit (17), and the control unit (17) being designed to move the switching device (19) to the active state when it receives at least the master reset signal (R1) and the actuator (15) is locked in contact with the safety switch (10).

2. The safety device according to claim 1, characterized in that It also comprises an auxiliary reset device (40) separated from the safety switch (10), the auxiliary reset device (40) is suitable for being operated by an operator, connected to the control unit (17) and designed to transmit an auxiliary reset signal (r2) thereto.

3. The safety device according to claim 2, characterized in that: The control unit (17) is designed to move the switching device (19) to the active state when the primary and secondary reset signals (R1, R2) are received and the actuator (15) is in contact with the safety switch (10).

4. A safety device according to any preceding claim, characterised in that The safety switch (10) comprises a seat (21) adapted to receive at least a portion of the actuator (15), and the locking mechanism (25) comprises a locking pin (26) movable between a locked position, in which the locking pin locks at least a portion of the actuator (15) in the seat (21), and an unlocked position, in which the actuator (15) is allowed to be removed from the seat (21).

5. A safety device according to any preceding claim, characterised in that The safety switch (10) further comprises a blocking member (37) adapted to be operated by a user and designed to transmit a locking signal (B) to the control unit (17), wherein the control unit (17) is designed to move the locking mechanism (25) to the locked state in response to the locking signal (B).

6. A safety device according to any preceding claim, characterised in that The safety switch (10) comprises a first communication device (30) and the actuator (15) comprises a second communication device (31) designed to remotely interact with the first communication device (30) when it is close to the first communication device (30), the first communication device (30) being connected to the control unit (17) and being designed to transmit a proximity signal (P) of the actuator (25) to the control unit (17).

7. A safety device according to any one of claims 2 to 8, characterized in that The control unit (17) is designed to detect a time interval (t) elapsed between the reception of the auxiliary reset signal (R2) and the main reset signal (R1), to compare the time interval (t) with a predetermined threshold value (t1), and to move the switching device (19) to the active state when the time interval (t) is below the predetermined threshold value (t1) and the actuator (15) is in contact with the safety switch (10).

8. A safety device according to any of the preceding claims, wherein the safety switch (10) comprises a housing (16) containing at least the control unit (17) and the switching device (19), characterized in that The main reset component (36) is a button directly fixed on the housing (16).

9. The safety device according to claim 1, characterized in that: The button is designed to transmit the master reset signal (R1) to the control unit (17) in response to the pressure that follows when the user releases the button.

10. A safety system comprising a machine (13) and a control device (101) connected to said machine (13) and designed to allow or not allow its operation, characterized in that It also comprises a safety device (10) connected to the control device (101) and designed to send thereto a signal associated with the state of the switching device (19), wherein the control device (101) is designed to allow or not allow the operation of the machine as a function of the signal associated with the state of the switching device (19).

11. A safety process for controlling access to a hazardous area protected by a safety device (1) according to any one of claims 1 to 9, wherein the process comprises: - a closing step (S1) of the movable guard (11), wherein the actuator (15) moves close to the safety switch (10); - a locking step (S2), wherein the locking mechanism (25) moves to the locking state, wherein the locking mechanism (25) locks the actuator (15) in contact with the safety switch (10); - a master reset step (S3), wherein the master reset member (R1) transmits the master reset signal (R1) to the control unit (17); - a switching step (S4), wherein the switching device (19) is moved to the active state when the control unit (17) receives at least the master reset signal (R1) and the actuator (15) is locked into contact with the safety switch (10).

12. The process according to claim 11, characterized in that: The locking step (S2) occurs before the master resetting step (S3).

13. The process according to claim 11, characterized in that: The blocking step (S2) occurs after the main resetting step (S3).

14. The process according to claim 11, 12 or 13, characterized in that The invention also comprises an auxiliary reset step (S5) before the main reset step (S3) and the locking step (S2), wherein the auxiliary reset member (40) transmits the auxiliary reset signal (R2) to the control unit (17).

15. The process according to claim 14, characterized in that: A processing step (S6) is included, wherein the control unit (17) detects a time interval (t) elapsed between receiving the auxiliary reset signal (R2) and the main reset signal (R1), and compares it with a predetermined threshold value (t1).

16. The process according to claim 15, characterized in that: The switching step (S4) occurs only when the time interval (t) is below the predetermined threshold (t1) and the locking mechanism (25) is in the locked state.

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