CONTROL DEVICE OF A PNEUMATIC ELEMENT

Abstract

A control device of a pneumatic element includes a supply circuit supplying compressed air to an inlet of the pneumatic element. The control device includes a normally closed monostable valve having an inlet connected to a compressed air source and an outlet connected to the inlet of the pneumatic element. A bistable valve has an inlet connected to the compressed air source and an outlet connected to a first control port of the normally closed monostable valve. A normally open monostable valve has a first inlet connected to the compressed air source and an outlet connected to a second control port of the normally closed monostable valve. The first and second control ports controls the opening and closing of the normally closed monostable valve. The valves are operable control the flow of compressed air.

Claims

1. A control device (1, 1) to control a pneumatic element (Ve, E, 2), the control device (1, 1) comprising a supply circuit (1.1) supplying compressed air for connecting to an inlet (2.1) of the pneumatic element (Ve, E, 2) and, in the supply circuit (1.1): a normally closed monostable valve (Vnc) having an inlet for connecting to a compressed air source (P) and an outlet for connecting to the inlet (2.1) of the pneumatic element (Ve, E, 2), and having a first control port (Vnc1) and a second control port (Vnc2), a bistable valve (Vb) having an inlet connected to said compressed air source (P) and an outlet connected to said first control port (Vnc1) of the normally closed monostable valve (Vnc), said first control port (Vnc1) being configured to control the closing of the normally closed monostable valve (Vnc), a normally open monostable valve (Vna) having a first inlet connected to said compressed air source (P) and an outlet connected to said second control port (Vnc2) of the normally closed monostable valve (Vnc), said second control port (Vnc2) being configured to control the opening of the normally closed monostable valve (Vnc), wherein the bistable valve (Vb) is able to take an open configuration to allow the compressed air to pass through, in which the inlet and the outlet of the same bistable valve (Vb) are connected, and a closed configuration to stop the compressed air from passing through, in which the inlet and the outlet of the same bistable valve (Vb) are disconnected and the outlet is connected to a nozzle(S) for venting the compressed air to atmosphere, and wherein the normally open monostable valve (Vna) is able to take an open configuration, in which the inlet and outlet of the same normally open monostable valve (Vna) are connected, and a closed configuration, in which the inlet and outlet of the same normally open monostable valve (Vna) are disconnected and the outlet is connected to the nozzle(S) for venting the compressed air to atmosphere.

2. The control device (1, 1) according to claim 1, wherein the open configuration of the normally open monostable valve (Vna) is an at rest configuration.

3. The control device (1, 1) according to claim 1, wherein the normally open monostable valve (Vna) comprises a spring element (4) configured to constantly exert a thrust on the normally open monostable valve (Vna) in the direction that brings the normally open monostable valve (Vna) into the open configuration.

4. The control device (1, 1) according to claim 1, in which the closed configuration of the normally closed monostable valve (Vnc) is an at rest configuration.

5. The control device (1, 1) according to claim 4, wherein the normally closed monostable valve (Vnc) is a pneumatic valve.

6. The control device (1, 1) according to claim 1, wherein the normally closed monostable valve (Vnc) comprises a spring element (3) configured to constantly exert a thrust on the normally closed monostable valve (Vnc) in the direction that brings the normally closed monostable valve (Vnc) into the closed configuration.

7. The control device (1, 1) according to claim 1, wherein the bistable valve (Vb) and the normally open monostable valve (Vna) are arranged in parallel in the supply circuit (1.1) and are pneumatically inserted between the compressed air source (P) and the normally closed monostable valve (Vnc).

8. The control device (1, 1) according to claim 1, wherein in a first configuration of the control device (1), referred to as activation configuration of the pneumatic element (Ve) or gripping configuration of a workpiece (O), the bistable valve (Vb) is closed, the normally open monostable valve (Vna) is open, and the normally closed monostable valve (Vnc) is open.

9. The control device (1, 1) according to claim 8, wherein in a second configuration of the control device (1), referred to as energy saving configuration, the bistable valve (Vb) is closed, the normally open monostable valve (Vna) is closed, and the normally closed monostable valve (Vnc) is closed.

10. The control device (1, 1) according to claim 9, wherein in a third configuration of the control device (1), referred to as deactivation configuration of the pneumatic element (Ve) or releasing configuration of the workpiece (O), the bistable valve (Vb) is open, the normally open monostable valve (Vna) is open, and the normally closed monostable valve (Vnc) is closed.

11. The control device (1, 1) according to claim 10, wherein in a fourth configuration of the control device (1), referred to as deactivation configuration of the pneumatic element (Ve) or releasing configuration of the workpiece (O), the bistable valve (Vb) is open, the normally open monostable valve (Vna) is closed, and the normally closed monostable valve (Vnc) is closed.

12. The control device (1, 1) according to claim 1, wherein the normally open monostable valve (Vna) is configured to open automatically in response to an electrical black-out.

13. The control device (1, 1) according to claim 1, wherein the normally open monostable valve (Vna) is a solenoid valve.

14. The control device (1) according to claim 1, wherein the bistable valve (Vb) is a solenoid valve.

15. The control device (1) according to claim 1, wherein the bistable valve (Vb) is a pneumatic valve and the control device (1) comprises a first monostable valve (Vm1) functionally interposed between the compressed air source (P) and a first control port (Vb1) of the bistable valve (Vb), and a second monostable valve (Vm2) functionally interposed between the compressed air source (P) and a second control port (Vb2) of the bistable valve (Vb), and wherein the first control port (Vb1) of the bistable valve (Vb) is configured to control the closing of the bistable valve (Vb), and wherein the second control port (Vb2) of the bistable valve (Vb) is configured to control the opening of the bistable valve (Vb).

16. The control device (1) according to claim 15, wherein the first monostable valve (Vm1) and the second monostable valve (Vm2) are arranged in parallel in the supply circuit (1.1) and are pneumatically inserted between the compressed air source (P) and the bistable valve (Vb).

17. The control device (1) according to claim 15, wherein in a first configuration of the control device (1), referred to as activation configuration of the pneumatic element (Ve) or gripping configuration of a workpiece (O), the bistable valve (Vb) is closed, the normally open monostable valve (Vna) is open, the normally closed monostable valve (Vnc) is open, the first monostable valve (Vm1) is open and the second monostable valve (Vm2) is closed.

18. The control device (1) according to claim 17, wherein in a second configuration of the control device (1), referred to as energy saving configuration, the bistable valve (Vb) is closed, the normally open monostable valve (Vna) is closed, and the normally closed monostable valve (Vnc) is closed, the first monostable valve (Vm1) is closed and the second monostable valve (Vm2) is closed.

19. The control device (1) according to claim 18, wherein in a third configuration of the control device (1), referred to as deactivation configuration of the pneumatic element (Ve) or releasing configuration of the workpiece (O), the bistable valve (Vb) is open, the normally open monostable valve (Vna) is open, and the normally closed monostable valve (Vnc) is closed, the first monostable valve (Vm1) is closed and the second monostable valve (Vm2) is open.

20. The control device (1) according to claim 19, wherein in a fourth configuration of the control device (1), referred to as deactivation configuration of the pneumatic element (Ve) or releasing configuration of the workpiece (O), the bistable valve (Vb) is open, the normally open monostable valve (Vna) is closed and the normally closed monostable valve (Vnc) is closed, the first monostable valve (Vm1) is closed and the second monostable valve (Vm2) is closed.

21. The control device (1, 1) according to claim 1, comprising an electronic control unit (CU) programmed to selectively and automatically control each valve (Vnc, Vb, Vna, Vm1, Vm2) based on a program and by feedback based on a signal generated by one or more air pressure sensors which are positioned in the supply circuit (1.1) or in the pneumatic element (2, E, Ve).

Description

BRIEF LIST OF THE FIGURES

[0049] Further characteristics and advantages of the invention will be more evident from the review of the following detailed description of its preferred, although not exclusive, embodiments depicted for illustration purposes only and without limitation, with the aid of the attached drawings, wherein:

[0050] FIGS. 1-4 are schematic views of a first embodiment of a control device according to the present invention, adapted to control a pneumatic element and shown in corresponding configurations of use;

[0051] FIGS. 5-8 are schematic views of a second embodiment of a control device according to the present invention, adapted to control a pneumatic element and shown in corresponding configurations of use.

DETAILED DESCRIPTION OF THE INVENTION

[0052] FIGS. 1-4 are construction diagrams of a first embodiment 1 of a control device according to the present invention, configured to control a pneumatic element Ve, such as the suction cup visible in the figures, or an ejector, or a subordinate pneumatic circuit, for example to allow an object/workpiece O to be picked up, moved or released. The pneumatic element Ve can be combined with a corresponding compressed air supply circuit 2 functionally interposed between the control device 1 and the pneumatic element Ve.

[0053] In the examples shown, the circuit 2 comprises a compressed air duct 2.1 connected to an outlet of the control device 1, and an ejector E which is on the duct 2.1 and equipped with a Venturi-type nozzle. The ejector E, which can be of conventional type, is in turn connected at 2.2 to a preferably silenced nozzle S for venting to atmosphere and to a suction hole/orifice connected to the pneumatic element Ve by a duct 2.3, so that compressed air passing through the ejector, from the duct 2.1 to the duct 2.2, causes air to be sucked through the pneumatic element Ve and along the duct 2.3. This allows the pneumatic element Ve to be depressurized when it is in abutment against the object O, allowing it to be lifted. For this reason, the pneumatic element Ve can be deformable.

[0054] Preferably, there is a calibrated check valve C along the duct 2.3, which has the task of preventing air from flowing in the opposite direction to the desired direction, i.e., preventing air from flowing from the ejector E to the pneumatic element Ve: this prevents or limits unwanted pressurization of the pneumatic element Ve. A filter F2 is placed along the duct 2.3, between the check valve C and the pneumatic element Ve, to filter the air sucked along the duct 2.3 and prevent malfunction of the ejector E caused by dust and impurities which can be otherwise sucked in.

[0055] The control device 1, also called regulator 1, has an inlet 1.2 connected to a source P of compressed air, such as a compressed air circuit of the type normally available at industrial sites. A filter F1 intercepts the incoming flow of compressed air from the source P, before it enters the control device 1, to prevent dust and impurities from entering the control device 1.

[0056] The control device 1 has an outlet 1.3 connected to the duct 2.1 of the circuit 2 to supply the ejector E, or, in applications in which the circuit 2 is not required, the outlet 1.3 is directly connected to the pneumatic element Ve.

[0057] In its first embodiment, the control device 1 comprises an inner compressed air supply circuit 1.1, which runs between the inlet 1.2 and the outlet 1.3.

[0058] In the circuit 1.1, a normally closed monostable valve Vnc is installed, the latter having a first operational inlet connected to the inlet 1.2 of the circuit 1.1 and, therefore, connected to the source P of compressed air, and having an operational outlet connected to the outlet 1.3 of the circuit 1.1, which in turn is connected to the circuit 2 or directly to the pneumatic element Ve. The source P supplies compressed air at a pressure higher than atmospheric pressure.

[0059] The monostable normally closed valve Vnc can take two operational configurations: a first configuration to allow air to pass through, called open valve, shown in FIG. 1, in which the flow of compressed air from the inlet 1.2 to the outlet 1.3 is allowed, and a second configuration to stop air from passing through, called closed valve, shown in FIGS. 2-4, in which the flow of compressed air to the outlet 1.3 is not allowed. The closed valve configuration is the at rest configuration; the open valve configuration is the energized/powered valve configuration. When the valve Vnc is open, its inlet and outlet are pneumatically connected, and vice versa, when the Vnc valve is closed, its inlet and outlet are pneumatically disconnected.

[0060] The normally closed monostable valve Vnc further comprises two (pneumatic) control ports, a first control port Vncl and a second control port Vnc2. The term port is used herein to refer to compressed air inlets which are configured to control the position of the valve.

[0061] Preferably, as shown schematically in the figures, the normally closed monostable valve Vnc comprises a spring element 3, such as a spring, configured to constantly exert a thrust on the movable components of the valve Vnc to bring the valve into the second configuration, that is, to close and keep the valve Vnc closed. In this condition, in order to open the valve Vnc it is necessary to overcome the force exerted by the spring 3.

[0062] Preferably, the normally closed monostable valve Vnc is a one-way valve, although a two-way valve can also be used.

[0063] The normally closed monostable valve Vnc is a pneumatic valve, meaning that the first configuration of open valve is switched to the second configuration of closed valve by exploiting the action of compressed air selectively supplied to the control ports Vnc1 and Vnc2, as will be explained in more detail below.

[0064] In the circuit 1.1 are additionally installed: [0065] a bistable valve Vb receiving compressed air from the source P through an inlet, and having an outlet connected to the first control port Vnc1 of the normally closed monostable valve Vnc, and [0066] a normally open monostable directional-control valve Vna, receiving compressed air from the source P through an inlet, and having an outlet connected to the second control port Vnc2 of the normally closed monostable valve Vnc.

[0067] Thus, the bistable valve Vb comprises an inlet connected to the source P and an outlet connected to the first control port Vnc1 of the valve Vnc, and can take two operational configurations: a first configuration to stop air from passing through, called closed valve, shown in FIGS. 1 and 2, in which the flow of compressed air from the inlet 1.2 to the first control port Vnc1 of the normally closed monostable valve Vnc is not allowed, and a second configuration to allow air to pass through, called open valve, shown in FIGS. 3-4, in which the flow of compressed air to the first control port Vnc1 of the normally closed monostable valve Vnc is allowed. When the valve Vb is open, its inlet and outlet are pneumatically connected, and vice versa, when the Vb valve is closed, its inlet and outlet are pneumatically disconnected.

[0068] Preferably, the bistable valve Vb is a one-way valve, but it can also be a two-way valve. The bistable valve Vb can be pneumatic, i.e., able to be driven by compressed air, but preferably it is an electrically-driven solenoid valve subjected to an electronic control unit of the programmable type, as will be explained below. The control unit CU controls the movements of the bistable valve Vb by bringing it from the first configuration into the second configuration, and vice versa, thereby determining whether or not to open and close the valve Vb and whether or not to send compressed air to the first control port Vnc1.

[0069] The normally open monostable direction-control valve Vna comprises an inlet connected to the source P and an outlet connected to the second control port Vnc2 of the valve Vnc, and can take two operational configurations: a first configuration called open valve, shown in FIGS. 1 and 3, in which the flow of compressed air from the inlet 1.2 to the second control port Vnc2 of the normally closed monostable valve Vnc is allowed, and a second configuration called closed valve, shown in FIGS. 2 and 4, in which the flow of compressed air to the second control port Vnc2 of the normally closed monostable valve Vnc is not allowed. When the valve Vna is open, its inlet and outlet are pneumatically connected, and vice versa, when the Vna valve is closed, its inlet and outlet are pneumatically disconnected.

[0070] Preferably, the normally open monostable directional-control valve Vna is a one-way valve, but it can also be a two-way valve. The normally open monostable directional-control valve Vna can be pneumatic, i.e., able to be driven by compressed air, but preferably it is an electrically-driven solenoid valve subjected to an electronic control unit of the programmable type, as will be explained below. The control unit CU controls the movements of the normally open monostable directional-control valve Vna by bringing it from the first configuration into the second configuration, and vice versa, thereby causing the normally open monostable directional-control valve Vna to be opened or closed.

[0071] In the example shown, the normally open monostable directional-control valve Vna is equipped with its own spring element 4, preferably a spring, arranged to constantly exert a thrust on the valve Vna that brings it into an open configuration.

[0072] The switch of the normally closed monostable valve Vnc from the open valve configuration to the closed valve configuration, and vice versa, is determined by the configurations selectively taken by the valves Vb and Vna at a given instant, and, in the example shown in the figures, also by the action of the spring 3.

[0073] FIG. 1 shows the control device 1 in an first activation configuration of the pneumatic element Ve or gripping configuration of the workpiece O, in which compressed air comes out of the outlet 1.3 and supplies the circuit 2 and the pneumatic element Ve, whose depressurization allows the workpiece O to be gripped, as shown, allowing it to be picked up and handled by a manipulator equipped with the pneumatic element Ve. The air pressure in the duct 2.1 served by the control device 1 is equal to the air pressure supplied by the compressed air source, that is, the pressure at 2.1 is equal to the pressure at 1.2.

[0074] The control ports Vnc1 and Vnc2 of the normally closed monostable valve Vnc are now used to control the opening of the normally closed monostable valve Vnc, and thus to bring the valve Vnc into its open valve configuration, when: [0075] the bistable valve Vb is in its closed valve configuration, and any compressed air in the valve Vb is vented to the atmosphere through the respective, preferably silenced, nozzle S, and [0076] the normally open monostable directional-control valve Vna is in the open valve configuration, as shown in FIG. 1, and air flows from the inlet 1.2 to the second control port Vnc2.

[0077] FIG. 2 shows the control device 1 in a second energy-saving configuration, in which the workpiece O remains gripped by the pneumatic element Ve although the latter is no longer supplied with compressed air: compressed air does not leave the outlet 1.3 and does not supply the circuit 2 and pneumatic element Ve, the latter exploiting the low pressure state created earlier during the depressurization shown in FIG. 1 to remain clung to the workpiece O, as shown. The air pressure in the duct 2.1 is equal to the atmospheric pressure and the check valve C helps to maintain the low pressure state in the pneumatic element Ve. Therefore, the workpiece O can be handled by the manipulator. Thus, in this configuration, the grip on the previously picked-up workpiece O is maintained, while avoiding waste of compressed air, which is not supplied to the circuit 2. Compressed air does not flow through the closed bistable valve Vb and does not reach the first control port Vncl of the normally closed monostable valve Vnc; any excess pressure that may be present is reduced by discharging air into the atmosphere through the preferably silenced nozzle S. The thrust exerted by the spring 3 on the normally closed monostable valve Vnc is not countered, with the result that the valve Vnc is brought into and remains in the closed-valve configuration, thereby cutting off the supply of compressed air to the circuit 2. The normally open monostable directional-control valve Vna is closed; any pressurized air that may be present is vented to atmosphere through the respective, preferably silenced, nozzle S. The pneumatic element Ve remains depressurized if the circuit 2 and the pneumatic element Ve itself prevent air from entering the circuit 2 or between the pneumatic element Ve and the workpiece O. In practical applications, some pressurization is allowable, as long as the pressurization rate of the pneumatic element Ve is compatible with the time required for the workpiece O to be handled, as provided by the production process. In any case, the value of the pressure in the circuit 2 and/or in the pneumatic element can be measured with a special sensor, and the electronic control unit can automatically return the control device 1 to the first activation/workpiece-gripping configuration when the measured pressure value exceeds a threshold value, based on feedback in relation to the sensor readings.

[0078] FIG. 3 shows the control device 1 in a third configuration of deactivation of the pneumatic element Ve or workpiece release, in which the workpiece O is voluntarily released from the pneumatic element Ve. In this configuration, the control device 1 is pneumatically decoupled from the circuit 2 and the pneumatic element Ve; the air pressure in the duct 2.1 is equal to atmospheric pressure. The bistable valve Vb is open and compressed air flows through the valve Vb and reaches the first control port Vnc1 of the normally closed monostable valve Vnc, thus helping, together with the spring 3, to close the normally closed monostable valve Vnc and keep it closed. Since the bistable valve Vb is open, the position taken by the normally open monostable directional-control valve Vna makes no difference. In the third configuration, the normally open monostable directional-control valve Vna is open: compressed air flows to the second control port Vnc2 of the normally closed monostable valve Vnc, however, this is not sufficient to counter the thrust exerted by both the spring 3 and compressed air supplied by the bistable valve Vb to the first control port Vnc1 of the normally closed monostable valve Vnc, with the result that the normally closed monostable valve Vnc remains closed.

[0079] FIG. 4 shows the control device 1 in a fourth configuration of workpiece release, in which the workpiece O is voluntarily released from the pneumatic element Ve. In this configuration, the control device 1 is pneumatically decoupled from the circuit 2 and the pneumatic element Ve; the air pressure in the duct 2.1 is equal to atmospheric pressure. The fourth configuration is similar to the third configuration described with reference to FIG. 3, except that the normally open monostable directional-control valve Vna is closed: compressed air does not flow to the second control port Vnc2 of the normally closed monostable valve Vnc and, therefore, the thrust exerted by the spring 3 and compressed air supplied by the bistable valve Vb to the first control port Vncl of the normally closed monostable valve Vnc keeps the normally closed monostable valve Vnc closed.

[0080] Table 1 below summarizes the description of the operation of the control device 1. During normal operation, that is in the absence of electrical black-outs, the control device 1 can take one of the four configurations described above.

TABLE-US-00001 TABLE 1 normal operation electrical black-out pressure pressure config. Vb Vna Vnc at 2.1 Vb Vna Vnc at 2.1 1 closed open open equal to the closed open open equal to the workpiece pressure of pressure of gripping the source P the source P 2 closed closed closed equal to closed open open equal to the energy atmospheric pressure of saving pressure the source P 3 open open closed equal to open open closed equal to piece atmospheric atmospheric releasing pressure pressure 4 open closed closed equal to open open closed equal to piece atmospheric atmospheric releasing pressure pressure

[0081] In case of power failure, the control device 1 can take four stable configurations only, one for each of the previously described four configurations, which ensure that the workpiece O is not accidentally released: [0082] in the first activation/workpiece-gripping configuration, the position of the valves Vb, Vna, and Vnc does not change, since the spring 4 keeps the valve Vna in the open position, which is the at rest position for this valve; [0083] in the second energy-saving configuration, the valves Vna and Vnc open up, since the spring 4 brings the valve Vna into the open position, which is the at rest position for this valve, thus causing the Vnc valve to open up; [0084] in the third configuration of deactivating the pneumatic element Ve or releasing the workpiece, the position of the valves Vb, Vna and Vnc remains unchanged, since the workpiece O has already been voluntarily released; [0085] in the fourth configuration of releasing the workpiece, the position of the valves Vb, Vna and Vnc remains unchanged, since the workpiece O has already been voluntarily released.

[0086] Thus, it is understood that the control device 1 according to the present invention implements both energy saving and safeguard/safety against power failures, while always ensuring that the workpiece O is effectively retained. Compared with solutions such as the one described in EP3867024, which involve the use of two solenoid valves D1, D2 arranged in series in the compressed air supply circuit, upstream of the normally closed monostable valve Vnc, the control device 1 provides a solution with valves or solenoid valves arranged in parallel, which solution allows a shorter circuit 1.1 to be adopted and allows greater responsiveness of the device 1. Indeed, the valves Vna and Vb are arranged in parallel in the compressed air circuit 1.1 and are pneumatically inserted between the source P and the valve Vnc.

[0087] As shown in the figures with the CU reference, the control device 1 preferably comprises an electronic control unit integrated therein. The control unit CU can be programmed to control the solenoid valves Vb and Vna according to specific programs, depending on the application, and, as mentioned above, preferably by feedback based on the air pressure value detected by a sensor (not shown) inserted into 2.1, or into the circuit 2, or into the pneumatic element Ve. This arrangement allows the switch from the second configuration to the first configuration to be controlled, when there is a risk of accidentally losing the workpiece O due to the pressure in the pneumatic element exceeding a threshold value, and vice versa, allows the switch from the first configuration to the second configuration to be controlled in order to save compressed air, repeatedly and alternately in time, for as long as it takes to handle the workpiece O until it is released, when the control unit CU controls the switch to the third or fourth configuration.

[0088] Due to the presence of the control unit CU, the control device 1 is automatic, i.e. it operates automatically, based on the program that is set individually each time.

[0089] FIGS. 5-8 are construction diagrams of a second embodiment 1 of a control device according to the present invention, in which in FIGS. 1-4 the same reference numbers denote the same components or components equivalent thereto. The second embodiment 1is similar to the embodiment 1, except that: [0090] the bistable valve Vb is a pneumatic valve not countered by a spring, and comprises a first control port Vb1 and a second control port Vb2 (pneumatic ports), and [0091] two additional valves are inserted into the circuit 1.1, a first monostable valve Vm1 functionally interposed between the source P of compressed air and the first control port Vb1 of the bistable valve Vb, and a second monostable valve Vm2 functionally interposed between the source P of compressed air and the second control port Vb2 of the bistable valve Vb.

[0092] Preferably, the bistable valve Vb is a one-way valve, but it can also be a two-way valve.

[0093] Preferably, the valves Vm1 and Vm2 are solenoid valves countered by respective spring elements (springs) 5 and 6 and equipped with nozzles S for venting compressed air to atmosphere.

[0094] Preferably, there is also the filter F1, even if it is not shown for the sake of simplicity.

[0095] Thanks to this configuration, the position of the bistable valve Vb can be pneumatically controlled, meaning that the bistable valve Vb can be configured selectively to be opened or closed based on the configuration taken at that moment by the two monostable valves Vm1 and Vm2, which must never be both open and can be both closed, or one can be open and the other closed.

[0096] FIG. 5 shows the control device 1 in a first activation configuration/gripping configuration of the workpiece O, in which the device 1 has to be coupled to the circuit 2 pneumatically. Compressed air comes out of the outlet 1.3 and supplies the circuit 2 and the pneumatic element Ve, whose depressurization allows the workpiece O to be gripped, as shown; the workpiece O can be picked up and handled by a manipulator equipped with the pneumatic element Ve. The air pressure in the duct 2.1 served by the control device 1 is equal to the air pressure supplied by the compressed air source, that is, the pressure at 2.1 is equal to the pressure at 1.2.

[0097] The control ports Vnc1 and Vnc2 of the normally closed monostable valve Vnc are now used to control the opening of the normally closed monostable valve Vnc, and thus to bring and keep the valve Vnc into its open valve configuration. To obtain this: [0098] the bistable valve Vb is in its closed valve configuration, [0099] the normally open monostable directional-control valve Vna is in the open valve configuration, as shown in FIG. 5, and air flows from the inlet 1.2 to the second control port Vnc2 of the valve Vnc. This is sufficient to overcome the thrust exerted by the spring 3.

[0100] To close and keep the valve Vb closed, the first monostable valve Vml is kept open (by the actuator, since it is a solenoid valve) by countering the spring 5, and the second monostable valve Vm2 is kept closed, under the action of the spring 6. In practice, therefore, the compressed air does not reach the first control port Vncl of the normally closed monostable valve Vnc, with the result that the compressed air that, coming from the normally open monostable directional-control valve Vna, reaches the second control port Vnc2, counters the spring 3 and keeps the valve Vnc open.

[0101] FIG. 6 shows the control device 1 in the second energy-saving configuration, in which the workpiece O remains gripped by the pneumatic element Ve although the latter is no longer supplied by compressed air: compressed air does not leave the outlet 1.3 and does not supply the circuit 2 and pneumatic element Ve, the latter exploiting the low pressure state created earlier during the depressurization shown in FIG. 5 to remains clung to the workpiece O, as shown. The air pressure in the duct 2.1 is equal to the atmospheric pressure and the check valve C helps to maintain the low pressure state in the pneumatic element Ve. Therefore, the workpiece O can be handled by the manipulator. Thus, in this configuration, the grip on the previously picked-up workpiece O is maintained, while avoiding waste of compressed air, which is not supplied to the circuit 2. The compressed air does not flow through the closed bistable valve Vb and does not reach the first control port Vnc1 of the normally closed monostable valve Vnc. The thrust exerted by the spring 3 on the normally closed monostable valve Vnc is not countered, with the result that the valve Vnc is brought into and remains in the closed-valve configuration, thereby cutting off the supply of compressed air to the circuit 2. The normally open monostable directional-control valve Vna is closed. The two monostable valves Vm1 and Vm2 remain closed.

[0102] The pneumatic element Ve remains depressurized if the circuit 2 and the pneumatic element Ve itself prevent air from entering the circuit 2 or between the pneumatic element Ve and the workpiece O. In practical applications, some pressurization is allowable, as long as the pressurization rate of the pneumatic element Ve is compatible with the time required for the workpiece O to be handled, as provided by the production process. In any case, the pressure value in the circuit 2 and/or in the pneumatic element can be measured with a special sensor, and the electronic control unit CU can automatically return the control device 1 to the first configuration of activating the pneumatic element Ve or gripping the workpiece O, when the measured pressure value exceeds a threshold value, based on feedback in relation to the sensor readings.

[0103] In the event of an electrical black-out, the normally open monostable directional-control valve Vna returns to an open position, as shown in FIG. 5, thus allowing air flow to the second control port Vnc2 of the valve Vnc, thereby restoring the first configuration of the device 1 shown precisely in FIG. 5, so as to ensure that the workpiece O is not accidentally released.

[0104] FIG. 7 shows the control device 1 in a third configuration of deactivation of the pneumatic element Ve or workpiece release, in which the workpiece O is voluntarily released from the pneumatic element Ve. In this configuration, the control device 1 is pneumatically decoupled from the circuit 2 and the pneumatic element Ve; the air pressure in the duct 2.1 is equal to atmospheric pressure. Since the valve Vm2 is open and the valve Vm1 is closed, the bistable valve Vb is open and compressed air flows through the valve Vb and reaches the first control port Vnc1 of the normally closed monostable valve Vnc, thus helping, together with the spring 3, to close the normally closed monostable valve Vnc and keep it closed. Since the bistable valve Vb is open, the position taken by the normally open monostable directional-control valve Vna makes no difference. In this third configuration, the normally open monostable directional-control valve Vna is open: compressed air flows to the second control port Vnc2 of the normally closed monostable valve Vnc, however, this is not sufficient to counter the thrust exerted by both the spring 3 and compressed air supplied by the bistable valve Vb to the first control port Vncl of the normally closed monostable valve Vnc, with the result that the normally closed monostable valve Vnc remains closed.

[0105] FIG. 8 shows the control device 1 in a fourth configuration of workpiece release, in which the workpiece O is voluntarily released from the pneumatic element Ve. In this configuration, the control device 1is pneumatically decoupled from the circuit 2 and the pneumatic element Ve; the air pressure in the duct 2.1 is equal to atmospheric pressure. The fourth configuration is similar to the third configuration described with reference to FIG. 7, except that the normally open monostable directional-control valve Vna is closed and the valves Vm1 and Vm2 are both closed: compressed air does not flow to the second control port Vnc2 of the normally closed monostable valve Vnc and, therefore, the thrust exerted by the spring 3 and compressed air supplied by the bistable valve Vb to the first control port Vncl of the normally closed monostable valve Vnc keeps the valve Vnc closed.

[0106] Table 2 below summarizes the description of the operation of the control device 1. During normal operation, that is, in the absence of electrical black-outs, the control device 1 can take one of the four configurations described above.

TABLE-US-00002 TABLE 2 normal operation electrical black-out pressure pressure config. Vb Vna Vnc Vm1 Vm2 at 2.1 Vb Vna Vnc Vm1 Vm2 at 2.1 1 c a a a c equal to the c a a c c equal to the workpiece pressure of pressure of gripping the source P the source P 2 c c c c c equal to c a a c c equal to the energy atmospheric pressure of saving pressure the source P 3 a a c c a equal to a a c c c equal to Piece atmospheric atmospheric releasing pressure pressure 4 a c c c c equal to a a c c c equal to piece atmospheric atmospheric releasing pressure pressure a = open; c = closed.

[0107] In the event of power failure, the control device 1 can take four stable configurations only, one for each of the previously described four configurations, which ensure that the workpiece O is not accidentally released: [0108] in the first activation/workpiece gripping configuration, the position of valves Vb, Vna, and Vnc does not change, since the spring 4 keeps the valve Vna in the open position, which is the at rest position for this valve. The valve Vm1 is brought into the closed position by the spring 5, but this does not change the configuration of the valve Vb, which remains closed; [0109] in the second energy-saving configuration, the valve Vna opens up due to the spring 4 and controls the opening of the valve Vnc. The valves Vm1 and Vm2 remain closed due to their respective springs 5 and 6; [0110] in the third configuration of deactivating the pneumatic element Ve or releasing the workpiece, the position of the valves Vb, Vna and Vnc remains unchanged, since the workpiece O has already been voluntarily released. The valve Vm1 remains closed and the valve Vm2 is brought to closing, pushed by the respective spring 6; [0111] in the fourth configuration of releasing the workpiece, the position of the valves Vb and Vnc remains unchanged, since the workpiece O has already been voluntarily released. The valves Vm1 and Vm2 remain closed due to their respective springs 5 and 6. Vna is brought to opening, pushed by the corresponding spring.

[0112] Thus, it is understood that the control device 1 according to the present invention implements both energy saving and safeguard/safety against power failures, while always ensuring that the workpiece O is effectively retained, with the same advantages described above in relation to the first embodiment 1.

[0113] The control unit CU, also in the device 1, is electronic and integrated therein, and can be programmed to control all the valves of the device 1 based on specific programs and based on the application, preferably by feedback based on the air pressure value detected by a sensor (not shown) inserted into 2.1, or into the circuit 2, or into the pneumatic element Ve.

[0114] Due to the presence of the control unit CU, the control device 1 is also automatic, i.e. it operates automatically, based on the program that is set individually each time.