Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
A VALVE ASSEMBLY FOR THE OPTIMIZED FILLING OF VOLUMES IN A PNEUMATIC NETWORK
Document Type and Number:
WIPO Patent Application WO/2014/083493
Kind Code:
A1
Abstract:
Described herein is a valve assembly (1; 1') in particular designed for use in a pneumatic network (N) and comprising a first valve (2), a second valve (4), and a third valve (6). The second valve (4) and the third valve (6) are configured to be swithced for performing different steps of a method for optimized filling of a pneumatic volume (V) connected to an outlet port (OP) of said valve assembly (1; 1'). The first valve (2) moreover performs the function of drawing flow of compressed air from the pneumatic network (N) and subsequently discharged the flow itself enriched by other contributions towards the user (V).

Inventors:
MARTINELLI MATTEO (IT)
ZAMBON IVAN (IT)
Application Number:
PCT/IB2013/060382
Publication Date:
June 05, 2014
Filing Date:
November 25, 2013
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SAFEN FLUID AND MECHANICAL ENGINEERING S R L (IT)
International Classes:
F15B13/02; F15B21/08
Domestic Patent References:
WO2012101593A12012-08-02
WO2012101593A12012-08-02
Foreign References:
US6502393B12003-01-07
DE3836371A11990-05-03
Attorney, Agent or Firm:
DE BONIS, Paolo (Notaro & Antonielli d'Oulxvia Maria Vittoria 18, Torino, IT)
Download PDF:
Claims:
CLAIMS

1. A valve assembly (1; 1' ) , particularly for use in a pneumatic network (N) , including:

- a first valve (2) having a first inlet port (8), an outlet port (10) and a variable passage area (12) between said first inlet port (8) and outlet port (10), said first valve (2) further including a second inlet port (14) fluid dynamically connected downstream said variable passage area (12), said outlet port (10) being furthermore connected to an outlet port (OP) of said valve assembly (1; 1' ) ,

- a second valve (4) which connects a first supply port (IP) of said valve assembly (1; 1') to said first inlet port (8), said second valve (4) being configured to be switched between a closed position and an open position,

- at least one third valve (6) which connects said second inlet port (14) to the external environment (AMB) , said third valve (6) being configured to be switched between an open position and a closed position,

- a control unit (CU) configured for the actuation (S4, S6) of said second (4) and at least one third valves ( 6) ,

wherein said second inlet port (14) is further configured for the fluid connection to a predetermined portion of said pneumatic network (N) ,

wherein said inlet port (IP) is configured for the fluid connection to a flow source of said pneumatic network (N) , and said outlet port (OP) is configured for the fluid connection to a user (V; CY) of said pneumatic network (N) .

2. The valve assembly (1; 1') according to Claim 1, wherein a first pilot valve (40) configured to be switched between a first operating position and a second operating position is operatively associated to said second valve (4), wherein said first pilot valve (40) is configured, in said first operating position, to connect a second supply port (IP') of the valve assembly (1; 1') to a driving area of said second valve (4) to convey a pressure signal (P4) for the actuation of said second valve (4).

3. The valve assembly (1; 1') according to Claim 1 or 2, wherein a second pilot valve (60) configured to be switched between a first operating position and a second operating position is operatively associated to said third valve (6), wherein said second pilot valve (60) is configured, in said first operating position, to connect a second supply port (IP') of the valve assembly (1; 1') to a driving area of said third valve (6) to convey a pressure signal (P6) for the actuation of said third valve (6) .

4. The valve assembly (1; 1') according to Claim 3, wherein each pilot valve (40, 60) includes an actuating solenoid (400, 600) and an elastic positioning element (410, 610) configured to maintain each pilot valve (40, 60) in the corresponding first operating position, each solenoid being configured to receive actuation signals (S4, S6) from said control unit (CU) .

5. The valve assembly (1; 1') according to any of Claims 3 or 4, wherein said first and second pilot valves (40, 60), in the respective first operating position, are configured to convey a pressure signal which causes a switching of the corresponding second (4) and third (6) valves in the respective open positions .

6. The valve assembly (1') according to any of Claims 3 to 5, including two third valves (6) in fluid communication with and connected in derivation with respect to said second inlet port (14) .

7. The valve assembly (1; 1') according to any of the previous claims, wherein said first valve (2) includes a main duct (MD) of the convergent-divergent type and incorporating said variable passage area (12) in corresponding of a restricted section thereof.

8. The valve assembly (1; 1') according to Claim 7, further including an inlet volume (IV) located fluid dynamically downstream of the main duct (MD) , wherein said inlet volume (IV) is furthermore in fluid communication with the second inlet port (14) by means of an inlet duct (15) in which a unidirectional valve (15) is arranged which is configured to allow a fluid flow only from said second inlet port (14) towards said inlet volume (10).

9. A method for supplying a fluid flow to a user in fluid communication with the outlet port (OP) of a valve assembly (1; 1') according to one or more of the preceding claims, the method comprising the steps of:

- detecting a flow request from said user (V; CY) ,

- switching said second valve (4) and said third valve (6) in closed position for a first time interval

( t ig ) /

- sucking in, during said first time interval

( trig ) , a first fluid flow from said predetermined portion of said pneumatic network through said second inlet port (14) of said first valve (2),

- switching said second valve (4) in open position in a second time interval (tasp) , subsequent to said first time interval (trig ) , thereby enabling an intake of a second fluid flow from said pneumatic network (N) through said first inlet port (8), and

- switching said third valve (6) in open position thereby enabling an intake of a third fluid flow from the external environment (AMB) through said second inlet port (14) at the same time as said second fluid flow .

10. The method according to Claim 9, wherein said step of detecting a flow request from said user (V; CY) includes reading, by means of said control unit (CU) , field signals (PS) directed to one or more filling valves (FV) connected to the outlet port of said valve assembly (1; 1'), said second ad third valve (4, 6) being furthermore switched by means of said control unit (CU) as a function of said field signals (PS) .

Description:
"A valve assembly for optimized filling of the volumes in a pneumatic network"

~k ~k ~k ~

Field of the invention

The present invention relates in general to valve assemblies for use in pneumatic networks. Specifically, the present invention relates to a valve assembly configured for managing the processes of filling of volumes in a pneumatic network, such as for example the chambers of a linear actuator.

Prior art and general technical problem

In a large number of industrial activities and, in an even more general way, in any activity that requires use of compressed air, massive resort is made to large air compressors and to tanks in which the compressed air is stored and kept at a predetermined pressure level, typically in the 5 to 16-bar range.

As known, the most commonly employed pneumatic users operate with operating pressures far below the ones at which the tank (or tanks) present in the pneumatic network is (are) kept, which is the reason why it is necessary to use pressure reducers upstream of the aforesaid users in order to make available compressed air at the right operating pressure. However, it is evident that in this way a marked dissipation of energy occurs on each pressure reducer.

In general, it may be stated that each pressure drop within a pneumatic circuit not accompanied by a compensatory variation of - the flow value entails a net loss of energy. This loss of energy is due to lamination, i.e., dissipation by friction inside the fluid of the amount of energy necessary to perform the pressure drop.

In pneumatic networks, in particular, there are very considerable levels of energy dissipation during the processes of filling of the volumes, i.e., of localized capacities within the network itself. A typical example is that of the filling of the chambers of linear actuators used for moving the various functional assemblies of a machine.

Recalling that the energy of a fluid current can be expressed as the product of the instantaneous pressure and the mass flow or else - in the case of a fluid accumulated in a tank - as the product of the pressure and the volume within the tank itself, in situations such as filling of a confined volume, the phenomenon of lamination is rather evident especially in the first steps of the filling transient.

In fact, during the filling transient a considerable lamination of fluid occurs at the inlet and at the outlet of the component (generally an air valve) that regulates the fluid flow towards the volume to be filled.

In this situation, over a certain time interval a fluid flow occurs with constant flowrate and characterized by a marked pressure drop. The values of flowrate and pressure drop decrease progressively on account of the pressurization of the air within the confined volume and go to zero when the latter assumes the same pressure level as that present upstream of the air valve that regulates the fluid flow.

It is clear that in a pneumatic network, even a medium-sized one, at each instant dozens of filling processes of this type occur, for example on account of the periodic activation conditions typical of certain production processes.

Illustrated schematically in Figure 1 is a terminal portion of a pneumatic network in which a volume V is located. This volume may be embodied, in practice, by a tank, by a linear pneumatic actuator, or by any other localized pneumatic capacity. A filling valve FV is in fluid communication with the volume V and with a portion of pneumatic network N that functions as source of supply of the fluid. The filling valve FV is in turn controlled by pilot signals PS of a pneumatic or electrical type.

Figure 1A illustrates an application of the conceptual scheme of Figure 1 to a device that is widely used, such as a linear pneumatic actuator CY. The linear pneumatic actuator CY includes a piston P movable within a cylinder and carrying a stem S that in this way, following the movement of the piston P, can be alternately retracted and extracted with respect to the cylinder. The piston P likewise defines a pair of chambers VI, V2 that define two pneumatic volumes.

The filling valve FV is here represented as a distributor with four ways and two positions comprising a first position Pi, the so-called "parallel-flow" position, and a second position P2, the so-called "cross-flow" position, which perform the operations of extraction and retraction of the stem S. The filling valve FV is governed through field signals PS according to pre-set control logics for the network, but gives rise to marked dissipation of energy as described previously .

The schematic view of Figure 1A illustrates the typical situation of any linear pneumatic actuator, as likewise of any volume within a pneumatic network: no particular measure is adopted to limit dissipation of energy.

To provide a numeric example, consider a tank having a capacity of 10 1 pressurized at 6 bar and connected through the valve FV to the actuator CY, for which it is possible to assume an average cubic capacity of the chambers VI and V2 of approximately 1 1.

According to the theoretical predictions, after five activations of the valve FV during which an extraction and retraction of the stem S is produced (activation and deactivation of the valve, respectively) , the pressure in the tank should be equal to half of the initial value.

However, on account of the energy losses due to lamination within the tank, the pressure is lower than 3 bar, and the difference between the latter pressure value with respect to the theoretical value of 5 bar multiplied by the volume that has flowed within the five activations of the valve FV supplies the amount of energy losses due to lamination. Above all, following upon each activation of the valve the energy accumulated in the chambers VI, V2 is irremediably dissipated in the environment.

There is thus evident the need to limit as much as possible the energy losses due to lamination in order to minimize the operating costs of a pneumatic network of any sort. Minimization of the costs clearly would contribute to a more efficient global operation of the network .

Object of the invention

The object of the present invention is to overcome the technical problem described previously. In particular, the object of the invention is to reduce to a minimum the energy losses due to lamination during the transients of filling of volumes within a pneumatic network .

Summary of the invention

The object of the invention is achieved by a valve assembly and by a method for controlling the valve assembly having the features forming the subject of one or more of the appended claims, which form an integral part of the technical disclosure herein provided in relation to the invention.

In particular, the object of the invention is achieved by a valve assembly, in particular for use in a pneumatic network, including:

- a first valve having a first inlet port, an outlet port, and a variable passage areapassage area between said first inlet port and said outlet port, said first valve further including a second inlet port fluid-dynamically connected downstream of said variable passage area, said outlet port being moreover connected to an outlet port of said valve assembly;

- a second valve, which connects a first inlet port of said valve assembly to said first inlet port, said second valve being configured to be switched between a closed position and an open position;

- at least one third valve, which connects said second inlet port to the external environment, said third valve being configured to be switched between an open position and a closed position; and

- a control unit configured for the actuation of said second and said at least one third valve,

wherein said second inlet port is moreover confgured for fluid connection to a predetermined portion of the pneumatic network, and

wherein said inlet port is configured for fluid connection to a flow source of the pneumatic network, and said outlet port is configured for fluid connection to a user of the pneumatic network.

The object of the invention is moreover achieved by a method for supplying a fluid fluid flow to a user in fluid communication with the outlet port of a valve assembly of the type just described, the method comprising the steps of:

- detecting a request of flow by said user; - switching said second valve and said third valve into a closed position for a first time interval;

- sucking in, during said first time interval, a first fluid flow from said predetermined portion of said pneumatic network through said second inlet port of said first valve;

switching said second valve into an open position in a second time interval, subsequent to said first time interval, thereby enabling an intake of a second fluid flow from said pneumatic network through said first inlet port; and

- switching said third valve into an open position enabling intake of a third fluid flow from the external environment through said second inlet port at the same time as said second fluid flow.

Brief description of the drawings

The invention will now be described with reference to the annexed drawings, which are provided purely by way of non-limiting example and wherein:

- Figure 1, described previously, is a schematic view of a portion of a pneumatic network in which there is a localized pneumatic capacity, i.e., a volume;

- Figure 1A, described previously, is a schematic representation of a practical application of the scheme of Figure 1;

- Figure 2 is a schematic view of a valve assembly according to various embodiments of the invention;

Figure 3 is a schematic view of a possible embodiment of a component indicated by the arrow III in Figure 2;

- Figure 4 is a schematic view of a variant of the valve assembly of Figure 2;

- Figure 5 is a perspective view of a practical embodiment of the valve assembly of Figure 4;

- Figure 6 is a perspective view according to the arrow VI of Figure 5;

- Figure 7 is a perspective view according to the arrow VII of Figure 5;

- Figure 8 is a perspective view according to the arrow VIII of Figure 5;

- Figure 9 is a transparency view of the valve assembly of Figure 4;

- Figure 10 is a cross-sectional view according to the trace X-X of Figure 8;

- Figure 11 is a cross-sectional view according to the trace XI-XI of Figure 8;

- Figure 12 is a cross-sectional view according to the trace XII-XII of Figure 8; and

- Figure 13 is a cross-sectional view according to the trace XIII-XIII of Figure 8.

Detailed description of preferred embodiments

With reference to Figure 2, a valve assembly according to various preferred embodiments of the invention is designated as a whole by the reference number 1 and is here represented by a dashed-and-dotted box to indicate that it comprises a series of distinct components. In the case where components already mentioned in the framework of the description of Figures 1 and 1A were again referred to, the same reference numbers will be used.

The valve assembly 1 comprises a first inlet port IP, a second inlet port IP', an outlet port OP, a first valve 2, a second valve 4, a third valve 6, and an electronic control unit CU operatively connected to the valves 4, 6 and possibly to the valve 2, as will be described hereinafter. The modalities of connection between the valves 2, 4, 6 and the control unit CU, as likewise the modalities of connection of the entire valve assembly 1 with respect to the filling valves FV will now be described in detail. The first valve 2 comprises a first inlet port 8, an outlet port 10, and a variable passage area 12, represented here schematically with the symbol of an adjustable flow restrictor, set between the first inlet port 8 and the outlet port 10. A second inlet port 14 is fluid-dynamically connected downstream of the variable passage area 12; in particular, it is connected between the section 12 and the outlet port 10. The outlet port 10 is moreover in fluid communication with the outlet port OP of the valve assembly 1.

In a preferred embodiment, the first valve 2 is built according to what is described in the international patent application published as WO 2012/101593 filed in the name of the present Applicant.

In the case in point, with reference to Figure 3, the valve 2 comprises a body B, provided in which are the first inlet port 8 and the outlet port 10. In the body B there are moreover provided:

- a main duct MD set fluid-dynamically downstream of the inlet port 8 and in fluid communication therewith; and

an intake volume IV set fluid-dynamically downstream of the main duct MD and in fluid communication therewith and an exit nozzle EN set fluid-dynamically downstream of the intake volume IV, and in fluid communication therewith and with the outlet port 10.

The terms "upstream" and "downstream" are used herein to refer to a direction of flow of fluid that substantially proceeds from the inlet port 8 to the outlet port 10.

The intake volume IV is moreover in fluid communication with the second inlet port 14 by means of an intake duct 15 inserted in which is a non-return valve 16 designed to allow a fluid flow only from the inlet port 14 to the intake volume IV. Preferentially, the non-return valve 16 is pre-loaded, for example with an elastic element 17, as illustrated schematically in Figure 3.

The main duct MD is substantially shaped as a converging-diverging nozzle (the so-called "De Laval nozzle") and comprises, in this embodiment, a converging stretch 18 in fluid communication with the inlet port 8 set fluid-dynamically downstream with respect thereto, a stretch with restricted section corresponding to the variable section 12 set fluid- dynamically downstream of the converging stretch 18 and in fluid communication therewith, and a diverging stretch 20 set fluid-dynamically downstream of the stretch with restricted section 12, in fluid communication therewith and set moreover fluid- dynamically upstream of the intake volume IV and in fluid communication therewith.

The stretch with restricted section 12 has a variable passage area that can be modulated via an actuator assembly 22 here represented schematically by a dashed line.

In the preferred embodiment, represented in Figure 2, the second valve 4 and the third valve 6 are valves with two ways and two positions, of a pilot-operated type. This means, as is known to the person skilled in the art, that the displacement of the moving element of the valve is obtained by means of a pressure signal managed by a further valve, which in this case is driven electrically.

For this reason, in Figure 2 the ensemble of each valve 4, 6 and respective pilot valves 40, 60 is comprised in a dashed-and-dotted box, associated to which is the same reference number as that of the valve in brackets. This does not, however, rule out the possibility of the valves 4, 6 integrating an on-board actuation assembly that hence does not require the use of pilot valves.

This having been said, the second valve 4 connects the inlet port IP of the valve assembly 1 to the inlet port 8 of the first valve 2.

The valve 4 is for this purpose switchable between a first operating position of a closed type, corresponding to a resting condition, where the connection between the port IP and the port 8 is interrupted, and a second open operating position, where the connection between the aforesaid ports is instead enabled. The valve 4 includes an elastic positioning element 4A that keeps the valve 4 in a normally closed position.

Operatively associated to the valve 4 is a first pilot valve 40 of the three-way, two-position type switchable between a first operating position and a second operating position. The pilot valve 40 includes an actuation solenoid 400 and an elastic positioning element 410 that keeps the valve 40 in a normally open position (first operating position) .

The pilot valve 40 is operatively connected to an electronic control unit CU, which is provided for sending an electrical signal S4 to the solenoid 400.

The control unit CU is a commonly used programmable electronic control unit, in itself known to the person skilled in the branch so that it will not be described in detail hereinafter.

In the first operating position, the first pilot valve 40 connects the second inlet port IP' to a surface of influence of the valve 4, by means of which it is possible to perform movement of the moving element of the latter. For this purpose, the valve 40 manages a first pilot line P4, which transmits a pressure signal substantially corresponding to the pressure that impinges upon the inlet port IP'. In the second operating position, fluid connection between the port IP' and the valve 4 is interrupted, and at the same time the surface of influence, upon which the pneumatic signal carried by the driving line P4 acts, is set in direct connection with a discharge (towards the environment) .

The valve 6 is preferentially identical to the valve 4 and is can be switched between an open position and a closed (resting) position, where an elastic positioning element 6A keeps the valve 6 in a normally closed position. The third valve 6 connects the second inlet port 14 to the external environment, designated by the reference AMB in brackets. Preferably set on the pneumatic line of connection between the external environment AMB and the valve 6 is a flow restrictor with variable passage area designated by the reference number 61, which can be obtained, in practice, with a threaded grubscrew that partializes a passage area in a variable way.

Operatively associated to the valve 6 is a second pilot valve 60 identical to the valve 40 (hence with three ports and two positions) that can be switched between a first operating position and a second operating position. The pilot valve 60 includes an actuation solenoid 600 and an elastic positioning element 610 that keeps the valve 60 in the normally open position.

The pilot valve 60 is operatively connected to the electronic control unit CU, which is configured for sending an electrical signal S6 to the solenoid 600.

It should be noted that in general it is preferable for the open position of the pilot valves 40, 60 to be of the one-way type, i.e., designed to allow a fluid flow only towards the surface of influence of the corresponding valves 4, 6.

Conversely, in both of the valves 4, 6 (normally closed) it is preferable for the open position to envisage the possibility of a bidirectional fluid flow.

Once again in a way similar to the first pilot valve 40, the second pilot valve 60, in the first operating position, connects the second inlet port IP' of the valve assembly 1 with a surface of influence of the valve 6, by means of which movement of the moving element of the latter is obtained. For this purpose, the valve 60 manages a second pilot line P6 that transmits a pressure signal substantially corresponding to the pressure that impinges upon the inlet port IP 1 .

In the second operating position, fluid connection between the port IP 1 and the valve 6 is interrupted, and at the same time the surface of influence upon which the pneumatic signal carried by the pilot line P6 acts is in direct connection with a discharge (towards the environment) .

It should be noted that the presence of a second inlet port IP 1 that substantially serves just the pilot valves 40, 60 is basically envisaged for the reason that the aforesaid pilot valves demand a more accurate filtering of the incoming air so that it is in general preferred to create a dedicated inlet port rather than a derivation from the port IP in so far as this renders more convenient the installation of a filtering element F (Figures 2, 4). The inlet ports IP and IP' receive, however, air from the same source; hence, they are in effect connected in derivation with respect to the pneumatic network, but in any case on the valve assembly 1 they are preferentially separate. This does not, however, rule out the possibility, in alternative embodiments, of having just the port IP, with a derivation that carries the supply to the valves 40, 60 that is provided inside the device and with a filtering element that is likewise incorporated within the device .

To come to the valve 2, the second inlet port 14 is moreover connected, by means of a connection stretch 140, to a predetermined portion of the pneumatic network N selected on the basis of an energy-density criterion. It should be noted, as will be seen hereinafter, that this does not rule out the possibility of the aforesaid predetermined and energetically dense portion being constituted by a user of the pneumatic network (for example, connected to the port OP) in so far as it is certainly legitimate to consider also a user as forming part of the pneumatic network N itself.

By way of example, indicated in brackets in Figure 2 is one of the possible solutions of connection of the assembly 1 to an energetically dense volume, which in this case is a portion of volume operatively associated to the volume the filling process of which is being managed. All this will emerge more clearly from an examination of Figure 4, where the user of which the filling processes are managed is a linear pneumatic actuator having two chambers which alternatively function as energetically dense environment. Of course, the energetically dense environment could be elsewhere, according to the characteristics of the network.

In other words (but this concept will emerge more clearly from the ensuing description) , the fluid connection of the second inlet port 14 to the pneumatic network N is obtained by selecting the point of connection from among the ones where there is the passage of a fluid current with a higher level of energy or where a stagnant environment characterized by a high pressure level exists.

The electronic control unit CU is moreover operatively connected to the filling valves FV, of which it reads and sends back, if necessary, the signal PS, which is also an input variable for the electronic control unit CU . It is moreover envisaged that the control unit CU be operatively connected to one or more sensors that are designed to supply information on the volume, the filling/emptying processes of which are managed by means of the valve assembly 1. In the case in point, where said volume were that of the chambers of a linear actuator (for example, the chambers VI, V2 - cf. Figure 1), the control unit CU would receive also a first signal and a second signal from a first sensor and a second sensor, respectively, designed to detect an end-of-travel condition of the piston P within the sleeve of the actuator (these are signals at input to the control unit CU, hence signals PSi N ) .

Alternatively, it is possible to send to the control unit CU a signal indicating that the controlled volume (VI or V2, according to whether a command for exit or a re-entry of the stem S has been issued) has been filled or that emptying of the energetically dense volume (V2 or VI, according to whether a command for exit or a re-entry of the stem S has been issued) has occurred. It is moreover possible to send both of the signals so as to increase the reliability of the information transmitted: one signal could perform a "diagnostic" function with respect to the data of the other signal, and vice versa. In the case of discrepancies, the control unit CU could send a signal of malfunctioning to the user. In any case, they are always signals PS IN .

To enable a clearer understanding of this characteristic, the field signals PS schematically represented in Figure 2 have been designated by the references PSi N and PS 0UT where "input" and "output" clearly refer to the control unit CU.

Operation of the valve assembly 1 is described in what follows.

The valve assembly 1 is logically and physically set upstream of an assembly for controlling the one or more filling valves FV operatively connected to the volume V. In the case in point, the inlet port IP is connected to a source of flow of the pneumatic network N, whereas the outlet port OP is connected to the one or more filling valves FV. Thanks to the control unit CU, the valve assembly 1 reads the field signals PS (PS IN ) that determine filling of the volume V and carries out, via the valves 2, 4, 6, a sequence of steps, the result of which is filling of the volume V to the desired pressure but with a reduced use of compressed air with respect to the situation corresponding to Figures 1, 1A.

The sequence of the various steps and the operations within the framework of each of these steps are managed by a set of instructions stored in a memory of the electronic control unit CU and compiled in a personalized way with respect to the characteristics of the pneumatic network N.

In brief, the valve assembly 1 and the control unit CU implement a method for delivering a fluid flow to a user in fluid communication with the outlet port OP, comprising the steps that will be described hereinafter.

A first step consists in detecting a demand of flowrate by the volume V by reading the field signal PS (PS IN ) I which determines, as has been said, actuation of the valve or valves FV and filling of the volume V. The field signal PSi N is sent by a device external to the valve assembly 1, for example, as a function of the instantaneous demands of flowrate by the volume V or in general by the pneumatic network. This step determines the start of a cycle of optimized filling of the volume V.

Following upon reading of the signals PSi N by the control unit CU, the latter sends signals S4 and S6 to the solenoids 400 and 600, respectively, which bring about switching of the pilot valves 40, 60 into the corresponding second operating positions, i.e. by venting the pilot lines of the valves 4, 6. Actuation of the pilot valves 40, 60 (hence in the final analysis of the valves 4, 6) is obtained as a function of the reading of the signals PSi N . It should be noted that in general the signals PSi N are read by the control unit CU but simply travel within the latter and are directed towards the valves FV (signals PS 0UT ) / substantially simultaneously with reading thereof by the control unit CU. However, there are situations where the control unit CU re-launches with its own energy the signals PS IN : this occurs whenever there is the need to set a temporal delay in transmission of the signal from the control unit CU to the valves FV (in this case, the signals PS 0UT would be delayed with respect to the signals PSi N ) .

In this way, the pilot signals carried by the lines P4 and P6 are instantaneously sent to zero, thus annulling the action on the surfaces of influence of the valves 4, 6 so that the latter are in turn switched into the corresponding closed positions thanks to the corresponding elastic positioning elements 410, 610.

In this connection, it should be noted that in conditions of normal operation at least the valve 4 is in an open position. The pilot valves 40, 60 for this purpose are normally in the first operating position (open) so as to carry constantly a pilot signal onto the corresponding surfaces of influence of the valves 4, 6. The reason for this is that, in the absence of electrical signals due to malfunctioning, it is possible in any case to keep the function of filling of the volumes unaltered by keeping open the valve 4 (as has been said) and the valve 6.

By ventingpilot lines of the valves 40, 60, the inlet port 8 of the valve 2 is thus isolated from the pneumatic network N, and connection of the second inlet port 14 to the external environment AMB is likewise closed .

The only connection with the pneumatic network N that still remains open is that of the stretch 140 to which air coming from a predetermined portion of the network N corresponding to an energetically dense area flows .

It should be noted in general that the valve assembly 1 is well suited to an installation of a personalized type in a pneumatic network since it is not possible to know beforehand, without knowing what is the network layout, where the energetically denser areas of the network are, i.e., the areas where the fluid has a higher level of energy and is in conditions of under-exploitation. For example, when filling a chamber of a linear pneumatic actuator, an energetically dense environment (as will be seen hereinafter in the subsequent Figure 4) may be constituted by the opposite chamber of the actuator, i.e., the one that undergoes emptying.

In addition to the aforesaid operations, during the first step a further operation is carried out that develops globally throughout a time interval t rig , and that consists in sucking in a first fluid flow through the port 14, i.e., from the predetermined, energetically dense, portion of the pneumatic network N. This first step takes the name of "regenerative step" of the cycle of optimized filling of the volume V. It should be noted that the valves 4, 6, remain switched in a closed position for the entire time interval t r i g .

Once the time interval t r i g has elapsed, and hence the first step is through, there follows a second step of the method, which consists in switching, via the control unit CU, the second valve 4 into the open position. This is obtained, in the embodiment described, by de-energizing the solenoid 400 through cessation of the signal S4, which causes switching of the pilot valve 40 into the first (open) operating position under the action of the elastic positioning element 410. The effect of this is switching of the valve 4 into the open position and consequent restoring of the fluid connection between the inlet port 8 and the inlet port IP of the valve assembly 1.

In this way, the compressed air, taken in from the pneumatic network N, passes through the variable passage area 12, and at the same time a second fluid flow is taken in through the second inlet port 14, by being taken from the energetically dense environment through the branch 140.

The section 12 can be kept at a fixed value determined by the characteristics of the pneumatic network N or can be varied dynamically by means of a pilot signal P12 that preferentially conveys the pressure value present within the energetically dense environment .

In other embodiments, the electronic control unit CU itself can be operatively connected to an actuator assembly that is configured for modulating the value of the area 12.

This second step unfolds over a second time interval t asp , subsequent to the first time interval t r ig, and takes the name of "intake phase". It should be noted that the mass flow that flows through the section corresponding to the outlet port 10 is greater than the mass flow of compressed air that is taken in directly from the inlet port IP (which thus corresponds to an effective expenditure in energy terms) and that passes through the inlet port 8, since the flow 10 is enriched also by the further amount of flow through the second inlet port 14.

Once also the second time interval t asp has elapsed, via the electronic control unit CU a command is issued for de-energization of the solenoid 600 through cessation of the signal S6. This defines a third step of the method and causes switching of the pilot valve 60 into an open position and likewise a consequent switching into an open position of the third valve 6 in so far as the pilot signal carried through the line P6, which brings the moving element of the valve 6 into the open position, is restored.

In this step, the valve 2 and the entire valve assembly 1 consequently work by taking in a third fluid flow from the external environment AMB through the second inlet port 14. This flow is discharged through the outlet port 10 together with the flow taken in from the pneumatic network N and entering from the port IP, this flow thus being lower than the one effectively sent to the volume V.

During this step, the restricted area is modulated as a function of the pressure signal P12; this modulation serves to adapt the fluid-dynamics of the system to the pressure conditions that are rapidly changing inside the volume V. At the end of the aforesaid step, according to the requirements of filling of the volume V, closing of the valve 4 could take place. If this were to happen, at the next cycle only the valve 6 would be closed, since the valve 4 is already closed.

Hence, the cycle of optimized filling develops using, in the sequence described above and possibly applying the superposition principle, three flows of fluid:

- a first fluid flow through the second inlet port

14 and the connection stretch 140;

- a second fluid flow through the inlet port 8 (and the inlet port IP) coming directly from the pneumatic network N and corresponding to an effective energy expenditure; and

- a third fluid flow taken in from the external environment AMB once again through the second inlet port 14.

It is evident that in this way the advantages of the valve 2 already described in the. patent document No. WO2012/101593 are exploited, and these are combined with the further addition of a source of flow provided by means of the connection of the second inlet port 14 to an energetically dense area of the network.

Normally, the flow that passes through the inlet port IP is found to be considerably reduced, typically by about 50%, with respect to what would instead be necessary using simply the filling valve FV supplied by the field signals PS. In addition, thanks to the valve assembly 1 also any dissipation of energy in energetically dense areas of the plant is minimized, said dissipation being, instead, inevitable with solutions of a known type.

With reference to Figure 4, in an advantageous variant of the present invention, the valve assembly 1 can be obtained by doubling the third valve 6. For this purpose, the valve assembly of Figure 4 is designated by the reference 1', and all the components identical to the ones described previously are designated by the same reference numbers already adopted previously.

In this embodiment, the valve assembly 1' comprises two valves 6 that connect the second inlet port 14 to the external environment AMB independently of one another. In other words, the port 14 gives out onto a node 141, from which there depart two connection ducts 140 that lead to the valves 6 - and are hence connected in derivation with respect to the port 14 - and are selectively set in fluid communication with the external environment AMB by means of the valves 6 themselves .

The remaining components of the valve assembly 1 ' are identical to those of the valve assembly 1, as likewise the modalities of connection.

Likewise associated to each valve 6 is the pilot valve 60, which (in the preferred embodiments described herein) receives an air flow directly from the second inlet port IP' and transfers it onto a surface of influence of the corresponding valve 6. On the discharge towards the external environment (AMB) of each valve 6 there is moreover set the flow restrictor 61, which preferentially once again may be embodied by a partializing threaded grubscrew.

As in the previous case, the valve 6 and the valve 4 can be provided in a different form without pilot valve. In any case, the function would remain identical, since, even in the case where the valves 4, 6 were actuated directly by means of a solenoid, the result would in any case be that of selective switching between the open position and the closed position, which, instead, in the embodiments described, is obtained indirectly via the action of the pilot valves 40, 60.

Also the process of filling of the volume V is substantially unvaried with respect to what has already been described. The only difference lies in the fact that doubling of the valve 6 enables management of the possible discharge of flow from the volume V with different timings, in response to specific different functional requirements.

Furthermore, thanks to doubling of the valve 6 it is possible to have an intake phase (with reference to the foregoing description) that can occur at different times simply by determining a sequential actuation of each of the valves 6. It should be noted moreover that Figure 4 reproduces the connection of the valve assembly 1' to a user that consists of a linear pneumatic actuator CY of the type illustrated in Figure 1 (where the same reference numbers are used) . The person skilled in the branch will appreciate that the linear pneumatic actuator CY can be connected with the same modalities also to the valve assembly 1 in the embodiment illustrated in Figure 2.

Leading into the filling valve FV, here for example of the four-way two-position type, are the port OP and the duct 140, which is in turn connected to a node 141 and to the second inlet port 14. On the opposite side of the valve FV there are instead two fluid connections to the chambers VI and V2 of the actuator. In the aforesaid chambers, there are moreover preferentially set two sensors (one per chamber) that send signals of the type PS IN to the control unit CU and are designated by VIS, V2S, respectively. These sensors (and consequently this applies to the signal carried thereby) may be, as already described, designed to detect an end-of-travel condition of the piston P within the sleeve of the actuator or designed to detect that the controlled volume (VI or V2, according to whether a command for exit or re-entry of the stem S has been issued) has been filled or that the energetically dense volume (V2 or VI, according to whether a command for exit or re-entry of the stem S has been issued) has been emptied. It should be noted that, even though the schematic representation of the figures refers to just one entity in order not to render the representation burdensome, it is possible to have the simultaneous presence both of sensors for detecting filling/emptying of the volume and of end-of- travel sensors. In this case, the control unit CU would receive at input (signals PSi N ) all the types of signals sent by the aforesaid sensors, i.e., the end- of-travel signal and the signal indicating that filling/emptying has gone through.

Also in this case, it is possible to send both of the signals VIS, V2S so as to increase the reliability of the information transmitted: one signal could perform a "diagnostic" function with respect to the data of the other signal, and vice versa. In the case of discrepancies, the control unit CU could send a signal of malfunctioning to the user.

Modulation of the value of the passage area 12 is obtained via the pressure signal P12, which substantially corresponds to the pressure value in the node 141. This signal, with reference to the dashed- and-dotted circle in Figure 3, is fed back to the command of a two-port two-position proportional valve, designated by the reference VP SEZ/ of a pneumatically controlled continuous type, which in effect constitutes the section 12. The aforesaid valve is normally open so that, in the absence of a pressure signal on the node 141, the section 12 has a maximum area of passage. The valve closes in proportion to the increase of the pressure in the node 141 so as to keep the fluid- dynamic shape of the duct MD optimized as a function of the pressure conditions.

Control of the valve VP SEZ could be of an electrical type managed via the control unit CU: in this case, it would become necessary to use a pressure transducer positioned on the node 141, the output signal of which should be connected to the control unit CU so that this can send a corresponding pilot signal to the valve VP SEZ .

It should be noted that, during the last step of the method described above, where the volume to be filled (the chamber VI or V2) is connected to the pneumatic network through the port IP, the pressure value that is set up in the chamber during emptying of the actuator (energetically dense environment) is proportional to the amount of closing of the flow regulator 61. This pressure value determines modulation of the restricted section 12, which starts to close to limit the consumption of air taken in from the pneumatic network N through the port IP. The value of the overpressure in the chamber being emptied defines in effect the rate of extraction/retraction of the stem S: since discharge is obtained through the valves 6, it is possible to regulate the rate of extraction /retraction of the stem S simply by acting on the grubscrews defining the flow restrictors 61.

With the presence of two valves 6 and two grubscrews 61 it is possible to vary very finely the rate of exit and of re-entry, and - as has been said - to manage movement of the stem with different timings.

It should be noted that it would be possible also to provide just one grubscrew 61, but this would represent a convenient solution basically in the case where the rates of exit and re-entry of the stem S are substantially identical. If it were not, it would be necessary to regulate the grubscrew 61 continuously in order to adapt the passage area identified by this as a function of the action of exit or re-entry.

Both of the valve assemblies 1, l 1 enable a marked energy saving in all the applications that envisage filling of pneumatic volumes or simply delivery of flow to a user. The reason for this is that, defining "efficiency of the operation of flow delivery" as the ratio between the energy delivered to a user connected to the valve assembly 1, 1' (useful effect) and the energy absorbed from the pneumatic network N through the first inlet port IP (energy expenditure) , there would be a numerator basically constituted by the product of the flow passing through the outlet port 10 (and hence OP) and the average pressure on the inlet port (at inlet) of the volume V (typically estimated across the filling valve or valves FV) . This average pressure may be expressed as the time integral of the product of the instantaneous . pressure and the instantaneous flow at inlet to the volume V divided by the time interval itself.

In the denominator there would, instead, be a quantity equal to the product of the pressure available on the inlet port IP, which is much higher than the average operating pressure of the volume V, and of the flow passing through the first inlet port 8. This flow is decidedly lower than the one that passes through the outlet port 10, which is instead enriched with the contributions of flow that pass through the second inlet port 14.

Hence, the efficiency increases as compared to a traditional filling process because the numerator is affected by all the contributions of flow that constitute the flow passing through the port 10, otherwise substantially equal to the flow passing through the port 8. It should be noted that, in the present description, where not otherwise specified, by the term "flow" is always understood the mass flow.

The inventors have found that the use of this device in a common pneumatic application such as the movement of a linear pneumatic actuator entails an average saving that can be estimated at about 50%.

With reference to Figures 5 to 13, a practical embodiment of the valve assembly 1' will now be described by way of example. All the components already described will be designated by the same reference numbers .

With reference to Figures 5 and 6, the valve assembly 1' is provided as a structure with three plates set on top of one another 1A, IB, 1C, where the plate IB is comprised between the other two. Provided in each of the plates are the connection channels between the various components of the valve assembly 1' and the seats for the valves 2, 4, 6, 40, 60.

Moreover provided on the plates 1A and 1C are the power and pilot ports already described and by means of which the valve assembly 1' can interface with a user.

Provided in particular on the plate 1A are the ports OP and the inlet of the channel 140.

Provided, instead, on the plate 1C (Figure 7) are the ports IP and IP'. Furthermore, provided in the plate 1C (as may be seen in Figures 5 and 12) are the seats for the valves 60 (also visible in Figure 12) and the seats for the threaded grubscrews 61 (also visible in Figure 12 ) .

Once again located in the plate 1C is a membrane actuator 201, which is configured for modulation of the restricted section 12 of the valve 2. Finally, provided in the plate IB are the seats for the valves 6 (visible in Figure 12), the seats for the valve 2 (Figures 10, 11, 13), for the valve 4 (Figures 10, 11), and for the valve 40 (Figure 13).

With reference to the transparency view of Figure

9, it is to be noted that all the so to speak "main" valves 2, 4, 6, substantially define cartridge structures with mutually parallel axes, X2, X4 , X6 respectively, and - in the figures - vertical. The pilot valves 40, 60 have, instead, axes, X40 and X60, respectively, that are mutually parallel, but orthogonal to the axes of the valves 2, 4, 6.

With reference to Figures 10, 11, 13, the valve 2 is preferentially obtained in the form of a cartridge 202, mobile within which is a poppet element 204. The cartridge 202 carries on its own outer surface four annular grooves, housed in which are corresponding 0- rings designated by the reference OR. These O-rings identify three annular bands that correspond to as many environments. A first annular band houses in fact a first circumferential array of radial holes defining the first inlet port 8. A second annular band houses a second circumferential array of radial holes that define the second inlet port 14, and finally, the third annular band houses a third circumferential array of radial holes that define the outlet port 10. It should moreover be noted that provided within the plate IB is also the seat for the one-way valve 15 of which the fluid connection with the port 14 may be noted, comprised, precisely, between two successive O-rings. It should moreover be noted that defined between the first and second arrays of holes are all the sections 18, 12, 20 of the converging-diverging main duct MD. The poppet element 204 is instead shaped like a body with cylindrical symmetry and substantially shaped like an hourglass. The poppet element 204 hence comprises two portions with widened section at the ends: the first, designated by 206, is able to slide in a corresponding guide seat in the plate 1A; the second, designated by 208, is housed within a cup 210 of the membrane actuator 201. This second portion with widened section, in a stretch radiusing with the rest of the poppet element 204, moreover defines the variable passage area 12 (Figure 10) .

All the components of the valve 2 described above share the axis X2, and the poppet element 204 is movable along the axis X2 within the cartridge 202 thanks to the action of the membrane actuator 201, which receives the signal P12 (see, for example, Figures 2, 3, 4) .

It should be noted that the valve 2 substantially traverses all the plates 1A, IB, 1C of the valve assembly 1', since the sleeve 202 functions in effect as a distributor of signals for the other components of the assembly 1' itself.

Finally, with reference to Figure 12, schematically represented therein is the path of the pilot signals P6 directed towards the valves 6 and the position of the elastic elements 6A that impinge upon the mobile elements of the valves 6. The reference PA6 designates a driving edge the valves 6, i.e., the area in which the passage area is exposed during movement of the moving element of the valves 6.

Finally, a triple black arrow indicates the connection ^ between the channel 140 and the valves 6: in other words, the circle at the top right in Figure 12 is merely the section of the node 141.

Of course, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein purely by way of non- limiting example, without thereby departing from the sphere of protection of the invention.