FIELD OF THE INVENTION

The present invention relates to a proportional angle seat fail-safe valve assembly comprising a valve and a linear motor of the kind recited in the preamble of claim 1 .

BACKGROUND OF THE INVENTION

Valve assemblies for interception and regulation of fluids and/or gases are presently known, comprising valves, whose shutter is controlled by a linear motor. This kind of preferably proportional control allows a high precision of opening and closing the valve, thus of the flow rate of the fluid, and is obtained through the electric power supply of the linear motor.

However, it has to be pointed out that this kind of control is a risk factor in case of absence of energy or power supply, such as fault and/or blackout of the electric system.

In absence of energy, the linear motor is standstill and the valve shutter may remain open, thus making a condition of potential risk, such as pouring of the potentially harmful working fluid, or even unwanted pressure in a conduit, with consequent further problems.

In this connection, the known prior art provides for a second valve, for instance an electromagnetic one, series connected and actuated in the abovementioned condition. This prior art situation has some important troubles. More particularly, us of a plurality of valves to warrant a safe condition in case of electric power failure, causes a considerable complication of the circuit, due to additional components, wiring, control systems and many others. Moreover, use of a plurality of valves only with the safety function in case of malfunction, is not able to attenuate phenomena such as water hammer, typical of pipes where said valves are used.

Moreover, just to avoid these problems of motor-operated valves, one avoids this kind of solution, opting for pneumatic controlled solutions, which are more expensive and complex from the control point of view, but can warrant a safety level that cannot be achieved by the prior art motor-operated valves. SUMMARY OF THE INVENTION

In view of this situation, the technical problem of the present invention, is to develop a proportional angle seat fail-safe valve assembly, being able to substantially remedy at least part of the mentioned drawbacks.

In the present disclosure, the term fail-safe, which is known and commonly accepted by a person skilled in this art, means a safety device, in other words a device free from failure.

In the frame of said technical problem, it is an important object of the invention to obtain a valve assembly that can be used either as a regulation assembly or as a fail-safe system, that is a safety system for a fluid-mechanical circuit.

Another important problem of the invention is to develop an angle seat valve assembly, that when operating as a safety system, provides for features against the water hammer.

Another important object of the invention is to develop such an integration of the motor-operated linear control with a safety device, that in case of energy failure, the shutter quickly returns to the closure position, thus preventing any leak and achieving safety of the controlled circuit.

Still an important object of the invention is to simplify and reduce the components of the fail-safe systems of fluid-mechanical circuits.

Moreover, an important object of the invention is to attain a motor-operated valve assembly having a very quick closing time in case of failure.

Finally, an important object of the invention is to attain such a motor-operated valve assembly that at the input restoration, is just ready to restart, without requiring to reset the control of motor position.

The technical problem and the mentioned objects are attained by a proportional angle seat fail-safe valve assembly as recited in the annexed claim 1 .

Preferred technical solutions are highlighted in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWING

The characteristics and advantages of the present invention are hereinafter illustrated by the detailed description of preferred embodiments hereof, with reference to the annexed drawing, in which:

Fig.1 is a sectional view of a preferred embodiment of the valve assembly of the present invention, showing the angle seat valve in the condition of open valve A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the figure, the valve assembly according to the invention is globally indicated by reference numeral 100.

The valve assembly 100 according to the invention is suitable to carry out a control and/or regulation inside a fluid-mechanical circuit using compressible and/or incompressible fluids, toxic fluids and generally any kind of fluid.

Said valve assembly 100 preferably is a proportional fail-safe valve assembly. In the present document, proportional control valve assembly means a valve assembly having the possibility of regulating the flow rate of a fluid in transit, thus not only an on- off regulation. Moreover, in the present document, fail-safe valve assembly means a valve assembly returning the valve to a safe condition for the installation, for instance in case of malfunction of one or more parts of installation components, fluid-mechanical circuit and/or electric power supply and so on.

Preferably, said valve assembly 100 comprises a valve 1 , a linear motor 2, and control means 4 of both said valve assembly 1 and said linear motor 2. Preferably, according to the present invention, said valve 1 is an angle seat valvel , Moreover, said linear motor 2 is a reversing linear motor.

As it will be clear hereinafter, said valve 1 is of the normally closed (NC) kind. Therefore, this valve can be operatively connected with said linear motor 2.

As shown in Fig.1 , said valve 1 comprises a valve casing 10 provided with a fluid inlet 10a and a fluid outlet 10b connected in a fluid-mechanic way through a shaped ledge 10c.

Preferably, according to the present invention, said valve further comprises a shutter 1 1 mirror-shaped in 1

The shutter 1 1 is preferably made of polymeric material, more particularly polytetrafluorethylene (PTFE). Said shutter is preferably circular and in a normal section it has a preferably flat peripheral portion acting as a ledge when closed. And a curved central portion having a convexity in respect of the fluid inlet 10a.

Said valve preferably comprises a coupling 12, in which a plunger 13 is arranged, which is operatively connected at one end 13a with said shutter 1 1 and at the opposite end 13b with said linear motor 2. Therefore, considering the valve 1 shown in Fig.1 , said linear motor 2 preferably acts as an actuation member for the plunger 13 of valve 1 , moving the relevant components of valve 1 , and generally adjusting the flow between inlet 10a and outlet 10b, moving through said plunger 13 said shutter 1 1 , which can contact said ledge 10c at least in one position.

The above illustrated connection between the preferably linear motor 2 and the plunger 13, may comprise a plurality of additional components suitable to transmit the motion and to control the position of plunger 13 and shutter 11 .

Moreover, said plunger 13 preferably is operatively connected with at least one spring 14. Said spring 14 can bring said valve 1 to a closed condition C, by moving said plunger 13 and said shutter 1 1 .

Finally, according to the present invention, said linear motor 2 may preferably be able to move said valve 1 only to an open condition A, while the motor is released and substantially does not make any action on said valve 1 , when the valve must be returned to the closed condition.

Consequently, in the above described embodiment of the present invention, said linear motor 2 can take said valve 1 to the open condition A, while said spring 14 can take said valve 1 to the closed condition C. In this configuration, dictated by engineering elements such as dimensioning of spring 14, motive power of the linear motor 2 and size of the valve, the motor 2 is able to move the components of valve 1 , i.e. plunger 13 and shutter 1 1 , in both directions, but substantially it is the spring 14 to act in one direction (closure C) and the motor 2 to act in the other direction (opening A). Advantageously, in this configuration, the spring 14 allows to save electric energy in the direction of closure C of the valve 1 . Moreover, preferably, said linear motor 2 can take said valve 1 to both the open condition A and the closure condition C. More preferably, said spring 14 can take said valve to the closed condition C only when said linear motor 2 has no power supply or when the valve release is actuated. Consequently, spring 14 acts as an element warranting the fail-safe condition.

Said control means, which for instance comprise electronic means known per se, such as a driver, an electronic board, or even a portion of software inside a computer or control processor, thus actuate said release or activation of valve 1 and more particularly of plunger 13 and consequently of the connected shutter 1 1. The control means 4 are therefore configured either to actuate the motor 2, when the valve 1 must be taken to the open condition A, or to actuate the plunger 13, when the valve 1 must be taken to the closed condition C.

Moreover, the control means 4 preferably comprise measuring means 40 of the position of shutter 1 1 , being at least able to differentiate the position of shutter 1 1 either in the open condition A or in the closed condition C. More particularly, the measuring means 40 are able to measure the accurate position of shutter 1 1 , for instance with a precision equal to or less than one tenth of millimetre. The measuring means 40 may for instance comprise an encoder measuring rotations made by motor 2 or the like.

Moreover, preferably, once the shutter 1 1 is released, thus the valve 1 is in the closed condition C, the measuring means 4o reset, as closed condition C, the place value of the shutter 11 . Consequently, the position of the shutter 1 1 is calculated starting from the last position of the closed condition C of the shutter, irrespective of the position of said shutter in respect of the other components.

Moreover, according to the present invention, the valve assembly 100 may be of the dry kind with fluid separation, wherein at least part of the valve assembly 100 is not wetted by the working fluid.

Indeed, said valve 1 preferably comprises also a fluid separation system 3 arranged between said coupling 12 and said plunger 13, said system 3 extending radially to said plunger 13. As it is known to a man skilled in this art, said systems is able to separate at least some components of the valve assembly 100 from the working fluid.

Moreover, preferably said system 3 of fluid separation comprises a Belleville washer 31 capable of energizing a plurality of V rings 32, said washer 31 and V rings 32 being tightened by a bush 33. Said bush 33 has also the function of slide guide for said plunger 13.

The described valve assembly 100 defines also an innovative method of operating a valve assembly 100, preferably of the above described type.

Said method comprises the closure of valve 1 by releasing the shutter 1 1 by means of the motor 2.

The method further comprises the measurement of the position of the shutter 1 1 in respect of a starting position, also called zero position, coinciding with a closure configuration C. Said starting position is being reset once the motor 2 releases the shutter 1 1 , due to an explicit command or an emergency such as a power failure or blackout.

The method comprises also the positioning of the shutter 11 by means of the motor 2 and the control means 4, as previously illustrated in the present disclosure.

The valve assembly 100 according to the invention attains important advantages.

Indeed, the main competitive advantages relate to the simplification of the circuit in which the valve is being introduced, i.e. eliminating an on-off valve and related wiring and control.

Moreover, the described angle seat valve assembly advantageously reduces the installation components, since it operates both as regulation and fail-safe system for a fluid-mechanical circuit.

Advantageously, the valve assembly according to the present invention warrants under any condition even of failure, a prompt return to the safety closure position, avoiding fluid pouring and further circuit problems.

Furthermore, it is possible to measure easily the position of the shutter 1 1 through the measuring means 40 because, even if the valve operation is interrupted, the position of the shutter 1 1 would be calculated starting from the last position of closed condition C of shutter 1 1 . Even possible wear condition of worn shutter 11 , with consequent presence of different closed conditions C, are automatically calculated by the measuring means 40, resetting the position when the shutter 1 1 is in closed position C, and only spring 14 acts on it.

Finally, in case of failure, spring 14 advantageously takes valve 1 back to the closed position, for instance when the power supply is restored, and the operation of the whole valve assembly 100 can be restored without needing external interventions.

It has to be pointed out that only some preferred embodiments were described and illustrated, but many alterations, additions, modifications and/or several combinations of the elements may be resorted to, however without departing from the general innovative concept nor from its protection scope, as resulting also from the annexed claims.