FR2626338A1 - VALVE PRESSURE TANK - Google Patents

Abstract

This is a pressure tank of the kind comprising a rigid body 10, and, therein, an elastically deformable separator 11 which divides the interior volume into two separate chambers 12, 13, with, for communication of the chamber 13 with the outside, an opening 14B controlled by a valve 20 comprising a valve 21 whose head 22 extends directly over a valve seat 23 surrounding said opening 14B and which is subjected to a spring 24 the biasing in the direction opposite to this valve seat 23. According to the invention, the upper surface 31 of the head 22 of the valve 21 being a spherical cap of radius R having in plan a circular contour of diameter D, said radius R and said diameter D are between them in the following relation: 0.8 <R / D <1.5 Application to pressure tanks.

Description

The present invention relates to a

  generally the pressure vessels of the type used, for example

  for example, as accumulators or pressure transmitters.

  It relates more particularly to the case where such a pressure reservoir comprises a rigid body, and, in it, a plastically deformable separator which divides the internal volume into two separate chambers, namely, a gas chamber and a chamber of liquid, with, for communication of the liquid chamber with the outside of the rigid body, in practice for serving a circuit, an opening of the rigid body controlled by a valve having a valve whose head extends to the plumb a valve seat surrounding said opening and which is subjected to resilient means urging it in the opposite direction to said

flap seat.

  In use, the valve is normally open, with the valve head maintained spaced from its valve seat by the elastic means associated therewith, usually a single spring-like coil spring, and the liquid chamber is filled 1.a pressure which, equal to that prevailing in the circuit served, is

  balanced by the pressure in the gas chamber.

  If, however, a depression appears in the circuit served, there is, for its part, a call for liquid that tends to empty the liquid chamber of the liquid it contains. Under the pressure of the pressure in the gas chamber, the elastically deformable separator is subject to expansion, which leads it to apply to the

  head of the valve controlling the opening of liquid -

  corresponding. In view of this application, the upper surface of this head, which in plan has a circular outline, is

usually more or less curved.

  In practice, it is usually in the form of a spherical cap. But, to this day, it is still relatively flat, the corresponding spherical cap having a radius

  much larger than the overall diameter of its outline.

  In any case, because of the combined effects, on the one hand, of the contact pressure of which it is the object of the elastically deformable separator as soon as it is thus applied on the upper surface of its head, and, on the other hand, of the suction of which it is also the object, from below, because of the liquid coming out, the valve of the valve controlling the orifice of liquid tends, in spite of the action of the elastic means urging it in the direction opposite to its seat, to close, and it is necessary that it be so to avoid extrusion of the separator Plastiquement deformable in the circuit served which would obviously be detrimental to a

good performance of the whole.

  But for some applications, at least, it is advantageous that the valve remains as completely open as possible for as long as possible, so that the flow of liquid outflow, commonly known as restitution, is maximum before closing, and that , thus, the effectiveness of

  pressure tank is itself optimal.

  To delay the closing of the valve, it is customary to increase the stiffness of the elastic means which

keep open.

  But, without any other, and experience confirms this, it can result in rapid damage to the separator

elastically deformable.

  In fact, in view of the resistance then offered by the elastic means of increased stiffness, this elastically deformable separator, when it is applied to the upper surface of the valve head, very quickly marries all of it, at the risk, on the one hand, of being injured in contact with the edge, always relatively acute, which delimits it, and at the risk, on the other hand, after bypassing this ridge, to be the object of a pinch between this valve head and the seat thereof, to the detriment, in either case, of its integrity, and

therefore, of its longevity.

  The present invention is based on the discovery that, by a simple preferential choice of geometric dimensions, it is possible to avoid such risks,

  while increasing the performance of the whole.

  Its purpose is a pressure reservoir

  such a choice of geometric dimensions.

  This pressure tank is of the type comprising a rigid body, and in this case an elastically deformable separator which divides the internal volume into two distinct chambers, namely a gas chamber and a liquid chamber, with, for communication of the liquid chamber with the outside of the rigid body, an opening of said rigid body controlled by a valve comprising a valve whose head extends perpendicular to a valve seat surrounding said opening and which is subjected to means resilient biasing it in a direction opposite to said valve seat, and is generally characterized in that, the upper surface of said head of the valve being formed, at least in its central zone, by a substantially spherical cap of radius R -and having in plan a circular outline of diameter D, said radius R and said diameter D are in the following relation to each other

08 <<1,5

  For example, the upper surface of this valve head is formed, in its entirety, of such a substantially spherical cap of radius R. As a variant, and according to a development of the invention, it is formed, in its central zone, of such a substantially spherical cap of radius R, having in plan a circular contour of diameter D and, Ds being its overall diameter, it comprises, annularly, around this central zone, a peripheral zone which extends,

  axially, on a height H between Q and Ds / 3.

  Experience shows, and the calculation confirms, that from the crown of the upper surface of the valve-head, so much more accentuated than is normally admitted, it follows that at every moment; the pressure according to which the elastically deformable separator is applied to this upper surface is advantageously more uniform and the corresponding resultant force is advantageously greater than that observed, the conditions being equal, moreover, with a top surface of the head; valve

flatter.

  This resulting force being thus higher, the stiffness of the elastic means & antagonistic effect which this valve is otherwise subject to may advantageously itself be higher, without resulting in any risk of pinching -for the elastically deformable separator by adopting, according to the invention, the value indicated above for the radius R. It is thus advantageously possible, for example doubling the stiffness of the elastic means used, the other parameters in play remaining constant, d ' increase by 40% the rate of return compared to what it is in the realizations

comparable known today.

  As a corollary, since the closing of the valve is delayed because of the stiffness thus increased by the elastic means which keep it open, the volume of liquid that can be returned by the pressure reservoir before this closure is itself increased, to the advantage its effectiveness, especially if it is a

  Pressure tank arranged to the horizontal.

  The characteristics and advantages of the invention

  will emerge from the description which follows,

  By way of example, with reference to the accompanying diagrammatic drawings, in which: FIG. 1 is a view in axial section of a pressure tank according to the invention, for the normal configuration of the elastically deformable separator that it comprises; FIG. 2 shows, on a larger scale, the detail of FIG. 1 indicated by an inset II on it, for the configuration that the elastically deformable separator takes when it is applied to the upper surface of the valve head. associated; Figure 3 is a view which, similar to that of Figure 2, relates to the prior art; FIG. 4 is a diagram illustrating the results obtained with the pressure tank according to the invention; FIG. 5 is a partial view, in elevation, of the head of the valve equipping the pressure tank according to the invention, for a variant embodiment of

this valve head.

  As illustrated in these figures, the pressure tank according to the invention comprises, in a manner known per se, a rigid body 10, with, in it, an elastically deformable separator 11 which separates the internal volume into two chambers distinct, namely a room

  of gas 12 and a liquid chamber 13.

  In the embodiment shown, the rigid body 10 is elongate, having a generally cylindrical middle portion and two ends generally

  hemispherical, and is made in one piece, par.

example by forming.

  In the center of its upper end, it comprises axially an opening 14A, and in the center of its lower end, it comprises axially, in alignment with the

previous, an opening 14B.

  At the same time, the plastically deformable separator 11, which is usually made of a synthetic material, of the elastomer type for example, chosen to have a certain elasticity and a sufficient gas tightness, is in shape

of bladder.

  By its outlet 15, which is circular, and which is established around the upper opening 14A of the rigid body 10, it is reported, internally, in this rigid body, a support 16 plating for this purpose this outlet 15 against

  the inner surface of this rigid body 10.

  For example, and as shown, this support 16 axially has a tip 17, through which it passes through the opening 14A of the rigid body 10, and by which it cooperates, beyond it, with means specific to the to securely fasten this body

rigid 10.

  The gas chamber 12 is formed by the internal volume of the bladder that forms the elastically d: formable separator 11 thus implemented, and, for its charging, the nozzle 17 of the support 16 thereof has, axially, a bore 18 duly controlled by a valve

visible in the figures.

  These arrangements are well known in themselves, and, not being part of the present invention,

  they will not be described in more detail here.

  Also knownly, the opening 14B of the rigid body 10, which is intended to allow communication, with the outside of this rigid body 10, the liquid chamber 13, the latter being defined by the part of the interior volume of this rigid body. 10 which is external to the bladder formed by the elastically deformable separator 11, is controlled by a valve 20, and it comprises a valve 21 whose head 22 extends vertically above a valve seat 23 surrounding said opening 14B and which is subjected to elastic means 24 urging it in the direction

opposite this valve seat 23.

  For example, the valve seat 23 belongs to a tip 25, which is suitably secured to the rigid body, extending on both sides of the opening 14B thereof, and which has a axially, for guiding the valve 21, a bore 26 in which is engaged & sliding the shank 27 of the valve 21, and, secondly, parallel to the axial bore 26, one or more bores 28 own To a communication from the

  liquid chamber 13 with the outside.

  In practice, it is by such a nozzle 25 that the pressure reservoir thus formed is adapted to be attached to the circuit to be served, ie, for example, that this nozzle 25 belongs to a T-fitting inserted on such a circuit, that he himself can be reported on a

such connection.

  Together, in the embodiment shown, the elastic means 24 associated with the valve 21 are constituted by a spring of the coil spring type, which, resting on a shoulder 30 of the nozzle 25, bears on the lower surface of the head 22 of the valve

  21, around the tail 27 thereof.

  Finally, also known per se, the upper surface 31 of this valve head 22 is formed, at least in its central zone, by a substantially spherical cap, and has, in plan, an outline

circular.

  In the embodiment more particularly shown in FIGS. 1 and 2, the upper surface 31 of the valve head 22 is formed, in its entirety, by

  such a substantially spherical cap.

  Let R be the radius of this substantially spherical cap, D the diameter of its circular contour and Ds the overall diameter of the circular contour of the whole of the

surface 31 concerned.

  In the case where, as in this case, the spherical cap of radius R extends over the entire surface

  31, these circular contours are merged.

  In practice, the corresponding circular contour is

  is materialized by a ridge 32 more or less softened.

  According to the invention, the radius R and the diameter D are between them in the following relation:

0.8 <<1.5

For example:

  R # D This is the case in the embodiment shown, in which, however, the radius R is slightly smaller than the diameter D.

  To appreciate the originality of such a choice

  geometric dimensions, refer to Figure 3, qgui

illustrates the prior art.

  As can be seen in this FIG. 3, the radius of the spherical cap forming the upper surface 31 of the head of a valve is usually much larger than the diameter of its contour, so that this surface

  upper 31 is much flatter.

  As illustrated by arrows P in FIGS. 2 and 3, the curved, more pronounced, according to the invention, of this upper surface 31 advantageously leads, when the plastically deformable separator It applies thereto, to a pressure contact point P which is more uniform, and which, in the central zone at least of this upper surface 31, is

higher.

  The resultant force is, therefore, itself greater. As a result, the conditions being equal, the stiffness of the elastic means 24 implemented

  can be increased, and for example doubled.

  As a result, as illustrated in the -

  2, the elastically deformable separator It never reaches, in practice, before the valve 21 is closed, the edge 32 delimiting the upper surface 31 of the head 22 of the latter, whereas, when, as shown in Figure 3, this upper surface 31 is flatter, it quickly reaches before this closure, this edge 32 and can therefore be subject to a pinch beyond

this one during this closing.

  Due to the increased stiffness of the elastic means 24, and as illustrated by the diagram of Figure 4, on which it is carried, on the abscissa, the restitution rate Q, and, in ordonnéAes, the residual volume V remaining, following a curve I for the pressure tank according to the invention and a curve II for a comparable pressure tank of the type known previously, the limiting flow of restitution Q is, with a pressure tank according to the invention, higher, and, together, the volume

residual V is lower.

  Because, moreover, that the elastically deformable separator 11 does not reach the head 32 of the valve head 22, this elastically deformable separator

  It is advantageously housed.

  For it to be more surely so, that is to say that the elastically deformable separator It is more surely spared, the stiffness of the elastic means 24 to which the valve 21 is preferably subjected is chosen so that the contact pressure P according to which this elastically deformable separator 11 is capable of being applied to the head 22 of this valve 21 is included, for the elastic separators

  most usual deformable materials, between 0.02 and 0.04 MPa.

  In the variant embodiment of FIG. 5, the upper surface 31 of the head 22 of the valve 21 is formed, in its central zone 33, with a substantially spherical cap of radius R having in plan a circular contour of diameter D, less than Ds, and it comprises, annularly, 'around this central zone 33, a peripheral zone 34 which extends, axially, over a height H between 0

and Ds / 3.

  When this axial height H is zero, we find

  the previous embodiment.

  Whatever the case, and as before, the radius R and the diameter D, in plan, of the circular contour of the spherical cap forming the central zone 33 of the valve head 22 are in the following relation to each other:

0.8 <<1, 5

  As previously, also, the radius R is, for example, close to the diameter D. However, because of the still substantially greater bulge of the upper surface 31 of the intake head 22, it is then advantageously possible to implement elastic means of even greater stiffness, by adopting, with respect to D, a radius R corresponding to the prescribed relationship, and thus to further increase the rate of return P, at the price, it is true, of a fatigue a little more accentuated for the separator Plastiquement deformable 11, * which, for at least some applications, is of no consequence, and therefore does not constitute a

disadvantage.--

  Preferably, the peripheral zone 34 that presents in this case the upper surface 31 of the valve head 22 is conical and this peripheral zone 34 and the central zone 33 that it extends are connected tangentially.

one to the other.

  Let C be the half-angle at the apex of the cone

  belongs the peripheral zone 34.

  There is, among the various parameters involved, the following relationships, which make it possible to determine the

one against another.

  In any event, since the peripheral zone 34 acts somewhat like a riser, there is little risk, in this case, that the elastically-deformable separator 11 will ever reach, or at least otherwise with a substantially zero contact pressure P

contour 32 of the set.

  There is therefore little risk that it will be the object of a

  any pinching when closing the valve 21.

  Of course, the present invention is not limited to the embodiments described and shown, but

  encompasses any variant of execution.

Claims (7)

  1. A pressure vessel of the kind comprising a rigid body (10), and, therein, an elastically deformable separator (11) which divides the internal volume into two separate chambers, namely, a gas chamber (12) and a liquid chamber (13), with, for communication of the liquid chamber (13) with the outside of the rigid body (10), an opening (14B) of said rigid body (10) controlled by a valve (20) having a valve (21) whose head (22) extends plumb with a valve seat (23) surrounding said opening (14B) and which is subjected to resilient means (24) urging it in the opposite direction said valve seat (23), characterized in that, the surface   upper (31) of the head (22) of the valve (21) being.   formed, at least in its central zone, by a substantially spherical cap of radius R and having in plan a circular contour of diameter D, said radius R and said diameter D are between them in the following relation: 0.8 <D C 1.5   Pressure tank according to Claim 1, characterized in that R # D 3. Pressure tank according to any one of   Claims 1, 2, characterized in that the surface   upper (31) of the head (22) of the valve (21) is formed, in its entirety, a substantially spherical cap of radius R. 4. Pressure tank according to any one of   claims 1, 2, characterized in that the surface   The upper end (31) of the head (22) of the valve (21) is formed in its central zone (33) with a substantially spherical cap of radius R having in plan a circular contouX of diameter D and Ds being its overall diameter, it comprises, annularly, around this central zone (33), a peripheral zone (34) which extends,   axially, on a height H between 0 and Ds / 3.   Pressure tank according to Claim 4, characterized in that the peripheral zone (34) of the upper surface (31) of the head (22) of the valve (21) is conical.   1 6. Pressure tank according to any one of   claims 4, 5, characterized in that the central area   (33) and the peripheral zone (34) of the upper surface (31) of the valve (21) tate (22) are connected tangentially to each other.   7. Pressure tank according to any one of   Claims 1 to 6, characterized in that the stiffness of   elastic means (24) to which the valve (21) is subjected is chosen so that the contact pressure (P) in which the elastically deformable separator (11) is capable of being applied to the head (22) of said valve (21) is between 0.02 and 0.04 MPa,