EP1627152A1

EP1627152A1 - Pitot check valve with variable throttle

Info

Publication number: EP1627152A1
Application number: EP04739127A
Authority: EP
Inventors: Mauro Guglielmi; Daniele Guglielmi; Claudio Ranieri
Original assignee: Gfluid Srl
Current assignee: Gfluid Srl
Priority date: 2003-05-07
Filing date: 2004-05-04
Publication date: 2006-02-22
Also published as: ITMO20030129A0; WO2004099626A1; ITMO20030129A1

Abstract

The invention relates to the field of valves for fluidodynamics. Inside a single block (2), there are two valves (3a, 3b) and a pilot element (5) positioned, aligned along a common axis (4). The said element can slide inside a space (7) defined by two stopping elements (6a, 6b). The valves (3a, 3b) contain holding seats (10a, 10b) fitted with an adjusting element (13).

Description

DESCRIPTION

PILOT CHECK VALVE WITH VARIABLE THROTTLE

Technical field

The invention relates to a valvular element for fluidodynamics, in particular of the adjustable, piloted throttle unidirectional type.

Background Art

Valves, whatever their type or function, are indispensable components in any fluidodynamic circuit. The presence of valves is indeed designed to deviate, control, regulate and impede the flow of fluid in the circuit in order to permit the opportune functioning of actuators and motors controlled by fluid.

There are various typologies of valves realised and present on the market and, among these, there are the so-called unidirectional piloted valves, so called because the controlling fluid flows through them following a preferential direction. Within this particular typology of fluidodynamic valves, there exists various embodiment possibilities, for example, single or dual-action embodiments.

In addition to the variety of embodiment possibilities for the aforesaid valves, there is a vast possibility of constructive forms for the said valves such as, for example, as a cartridge or on a line or as a manifold or flanged.

In very many practical cases, it is necessary to add to the pilot function of the valve itself a regulating function relating to the quantity of fluid passing through the said valve. The aforesaid pilot function is performed, generally, by sliding elements called small pilot pistons which, moving along their longitudinal axis by means of the fluid's thrusting action through the valve, determine the opening and closing of the opposing transit ways created for the fluid in the body of the said valve. It should be noted that, in current embodiments of unidirectional piloted valves the functioning is of either a fully open or a fully closed type as the pilot element moves fully to the stroke limit in both directions. The regulation function relating to the quantity of fluid transiting through the valves, conventionally called throttling, is performed by means of various typologies of regulation of the openings of the passageway holes for the said fluid such as, for example, needle elements which are adjusted by screwing or unscrewing the said elements or spring elements whose springs can be calibrated, or elements which can be screwed circumferentially. The said regulation is designed to reduce the opening of the passageway for the manoeuvring fluid in order to adapt the performance of the individual valves to the actual operative requirements. Currently, if both the pilot function of the valves and the throttling function of the control fluid's passageway are required contemporaneously, a throttle device is added to the unidirectional piloted valve, said throttle device either corresponding with a body which is external to the single piloted valve or being incorporated into an integrated unit where the said throttle is separate from the said unidirectional piloted valve, both the said current solutions having certain drawbacks, the main drawbacks being established as the possibility of fluid leaks, the overall dimensions and the cost. With regards to the fluid leaks, these characterise, as it can be inferred, the embodiments in which the two elements, valve and throttle are materially separate. Even the coupling of the two said elements, performed directly, i.e. without the presence of intermediary pipelines, can be subject to leaks as the said coupling envisages the indispensable presence of static seals which, due to both the ageing of the material of which the said seals are composed and the imperfect execution of surface machining on the seats of the said seals, can let the control fluid seep through. The said leaks generate, consequently, a loss of charge throughout the circuit and therefore the decline of the said circuit's performance.

With regards to the losses of charge, it should be noted that the latter, in the current embodiments, are also derived from the notable quantity of holes, curves, piping and suchlike which are characteristic of the aforesaid embodiments characterised by the fact that the valves and throttles are separate from each other.

With regards to the overall dimensions, these constitute a drawback as, in the case of the valve and throttle which are physically separate, there is a substantial doubling of the volume occupied and, in the case of the valve and the throttle united in a single block, this envisages, in the embodiments realised until now, the presence of the said valve and the said throttle on two different planes, this fact necessarily entailing the obtaining of single blocks of considerable dimensions and weight. The reasons for the drawback represented by the production costs of the current embodiments of unidirectional valves fitted with throttles are evident if one thinks of the overall quantity of material required, the quantity of machining necessary and the quantity of elements, many of which are subject to movements and require machining with extremely limited tolerances, constituting the valve and throttle.

In other words, it can be said that all the drawbacks mentioned above are the direct consequence of the fact that, until now, no other device has been realised which is capable of effecting the throttling function by means of limiting the small pilot piston's stroke. Disclosure of Invention

The aim of this invention is to overcome all the aforesaid drawbacks. In particular, the valvular element for fluidodynamics, in particular of a unidirectional piloted single-block type, is fitted with at least one valve and one pilot element for the said valve, characterised by the fact that the said valvular element comprises two stopping elements positioned along the longitudinal stroke of the said pilot element and reciprocally separated by a space, inside which the pilot element is positioned, whose axis of movement coincides with a longitudinal axis of symmetry of at least one valve, the said two stopping elements being designed to limit the movement of the pilot element, and by the fact that an adjusting element is centred axially in relation to the aforesaid longitudinal axis of symmetry, said adjustable axis being designed to vary the position of at least one holding seat in relation to the position of the pilot element and therefore to divide the flow of fluid through the said valvular element into parts. These and other characteristics will better emerge in the description that follows of a preferred embodiment illustrated, purely in the form of a non- limiting example, in the drawing enclosed, in which:

- figure 1 shows a total longitudinal section of the valvular element in question in this invention; - figure 2 shows the functional diagram of the said valvular element. With reference to the figures, 1 is a valvular element composed of a single block 2 containing two valves 3 a and 3b of the unidirectional dual-action type, both the said valves extending along a single longitudinal axis of symmetry 4.

The said longitudinal axis of symmetry coincides with the longitudinal running axis of a small pilot piston 5. Two elastic rings 6a end 6b, respectively the first and second, are fitted in suitable seats created in the single block 2 and are centred in relation to the longitudinal axis of symmetry 4. The said two elastic rings are reciprocally separated by a space 7 which corresponds with the possibility of movement of the small pilot piston 5 positioned between the said two elastic rings.

The small pilot piston 5 has two pins 8a and 8b, opposite each other and centred according to the longitudinal axis of symmetry 4, each of which is facing one of the two small holding pistons 9a and 9b that are parts, respectively, of the valve 3a and 3b. Each of the small pistons 9a and 9b beats against a relative holding seat, respectively 10a and 10b, thanks to a spring 11. The said spring is contained within the said holding seat integrally restrained by a means of connection 12, for example a cylindrical pin as shown in figure 1, to a coaxially threaded adjusting screw 13 inside a valve body 14. The longitudinal axes of both the said valve body and the said adjusting screw correspond with the longitudinal axis of symmetry 4. The said holding seats are provided with a plurality of holes 23 bored radially into the depth of the said holding seats. A fastening nut 15 is positioned at the external end of the adjusting screw 13.

In the single block 2 there is a first and a second inlet opening, respectively 16 and 17, and there is a first and a second outlet opening, respectively 18 and 19. The said inlet openings are linked to a pump and a distributor not shown, while the outlet openings are linked to a driving element 20 in figure 2 which shows schematically a dual-action cylinder. 20a and 20b are a delivery chamber and a return chamber respectively of the said driving element 20.

In the single block 2 there is also a first and a second chamber, respectively 21 and 22, reciprocally separated by the presence of the small pilot piston 5 and related, respectively, to the openings 16 and 18 and the openings 17 and 19.

There will now follow a description of the functioning of this invention, using the references indicated in the figure. Coming from the pump and the distributor, not shown, the fluid enters the valvular element 1 through the first inlet opening 16, filling the first chamber 21. At this point the fluid pressure generates two effects: the movement of the small holding piston 9a with compression of the relative spring 11 and the movement of the small pilot piston 5 towards the holding piston 9b.

The withdrawal of the small holding piston 9a results in the said piston beating no longer against the holding seat 10 and the fluid can move through the plurality of holes 23 in the valve 3 a and flow, through the first outlet opening 18, towards the delivery chamber 20a of the dual-action cylinder 20. Contemporaneously, the pressure of the fluid present in the first chamber 21 pushes the small pilot piston 5 towards the elastic ring 6b and brings the pin 8b into contact with the small holding piston 9b. If the pressure of the fluid in the first chamber 21 is great enough to overcome the resistance of the spring 11 of the valve 3b, the pin 8b detaches the holding piston 9b from the relative holding seat 10b; in this way the passage of the fluid coming from the return chamber 20b is obtained.

The elastic ring 6b limits the stroke towards small holding piston 9b of the small pilot piston 5, preventing the latter compressing the spring 11 of the valve 3b completely, thereby obtaining a throttling action in relation to the passage of the fluid from the return chamber 20b. This prevents, in practice, the valve 3b functioning either fully open or fully closed, regulating the flow depending on the operative requirements. In other words, it prevents the valvular element 1 functioning simply as a unidirectional valve which is either fully opened or fully closed.

In the inletting direction, therefore, the valve in question in this invention functions as a normal open unidirectional valve, while in the returning direction, it functions as an adjustable throttle. By means of the rotation of the adjusting screws 13 the position of the small holding pistons 9a and 9b can be varied inside the single block 2 in order to vary the moment of contact between the pins 8a and 8b and the small holding pistons 9b and 9a facing the said pins. If, for example, the seat 10b is operatively positioned as shown in the figure 1, the pin 8b, during its movement towards the right-hand side of the said figure, will come into contact with the holding element 9b almost immediately and the latter, compressing the spring 11 to the maximum, will move by a distance corresponding to the movement made by the small pilot piston 5 until the latter beats against the elastic ring 6b. This situation corresponds with the maximum opening of the passageway for the fluid running from the opening 19 to the opening 17, i.e. for the fluid leaving the return chamber 20b of the dual-action cylinder 20. On the contrary, if the adjusting screw 13 is rotated so that the seat 10b is positioned further to the right than indicated in figure 1, it is possible to ensure the pin 8b, during its movement towards the right-hand side of the said figure, comes into contact with the holding element 9b when the pilot element practically beats against the elastic ring 6b. This situation corresponds with the minimum opening, the zero limit, of the passageway for the fluid running from the opening 19 to the opening 17.

The fluid coming from the return chamber 20b, on filling the second chamber 22, brings about an inversion of the movement of the small pilot piston 5 obtaining a function which is contrary but similar to that described earlier. A first advantage of this invention is represented by the reduction in the overall dimensions and weight of the piloted valvular element performing, contemporaneously, the function of unidirectional dual-action valve and the throttle function. A further advantage consists in the reduced production cost thanks to the lesser quantity of material used, of elements used and the construction simplicity.

In the description explicit reference is made to a piloted valve of the unidirectional type, but it is extremely evident that the art of this invention can also be applied, advantageously, to any typology of valve for fluidodynamics, in which there is at least one pilot element present, whether it is of the blow-down, balancing, sequence or any other kind. In the same way, reference is made in the description to the single block 2 but it is evident that this element can also be constituted, advantageously, of a cartridge.

Claims

1. A valvular element (1) for fluidodynamics, in particular of a unidirectional piloted, single-block type, fitted with at least one valve (3a) and/or (3b) and one pilot element (5) for the said valve, characterised by the fact that the said valvular element comprises two stopping elements (6a, 6b) positioned along the longitudinal stroke of the said pilot element and reciprocally separated by a space (7), inside which the said pilot element is positioned, whose axis of movement coincides with a longitudinal axis of symmetry (4) of at least one valve (3 a) and/or (3b), the said two stopping elements being designed to limit the movement of the pilot element (5), and characterised by the fact that an adjusting element (13) is centred axially in relation to the aforesaid longitudinal axis of symmetry, the said adjusting element being designed to vary the position of at least one holding seat (10a) and/or (10b) in relation to the position of the pilot element (5) and therefore to divide the flow of fluid through the said valvular element into parts.

2. A valvular element according to claim 1, characterised by the fact that at least one holding element (9a) and/or (9b) is connected to the relative holding seat (10a,10b); the adjusting element (13) being designed to vary the distance between the at least one holding element (9a) and/or (9b) and the pilot element (5).

3. A valvular element according to claims 1 and 2 characterised by the fact that the space (7) and the at least one adjusting element (13) are reciprocally complementary, the said complementary nature permitting the said valvular element to perform, contemporaneously, both the pilot function of at least one valve (3 a) and/or (3b) and the regulation of the flow of the work fluid through the said valvular element.

4. A valvular element according to claim 1, characterised by the fact that the stopping elements (6a, 6b) can be a variety of kinds, for example, elastic rings.