US3732888A

US3732888A - Closing device for a pneumatic system

Info

Publication number: US3732888A
Application number: US00233601A
Authority: US
Inventors: M Convain; P Meresse
Original assignee: PRONAL SA
Current assignee: PRONAL SA
Priority date: 1972-03-10
Filing date: 1972-03-10
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15

Abstract

A closing device for a pneumatic system comprising an inflatable bag having a closing face co-operable with an annular seat defining an aperture which is connected to the pneumatic system by passage means. The bag has an orifice which conduit means puts in communication with the interior of the passage means so that pressure variations in the passage means inflate or deflate the bag so that the closing face closes or unmasks the annular seat. The bag consists of two fluidtight sheets interconnected along their peripheries and means are provided inside the bag to ensure that the two sheets are always spaced apart in the region of the orifice. The device can be employed in combination with the inlet of fluid-flow generating means to control the fluid flow through the inlet.

Description

[ 1 3,732,888 May 15, 1973 FOREIGN PATENTS OR APPLICATIONS CLOSING DEVICE FOR A PNEUMATIC SYSTEM Inventors:

5 9 Marcq-en- Baroeul; Pascal Meresse, 59 Roubaix, both of France Michel Convain,

Primary ExaminerHenry T, Klinksiek' Assistant ExaminerRobert J. Miller Attorney-John Lezdey [73] Assignee: Societe Anonyme Pronal, Roubaix,

France [57] ABSTRACT A closing device for a pneumatic system com prising an inflatable bag having a closing face co-operable with an annular seat defining an aperture which is connected to the pneumatic system by The bag has an ori 2 7 9 l 0 10 3 m3 2 o N .m.l. 0. MD. FA 1.] 2.1. 22 [I [52] U.S. Cl. ............137/489, 137/502, 251/61.1, passage means. 92/92 fice WhlCh condult means puts 11'] communication with the interior of the passage means so that pressure variations in the passage means inflate or deflate the bag so that the closing face closes or unmasks the annular seat. The bag consists of two fluid tight sheets interconnected along their peripheries and [56] References Cited means are provided inside the bag to ensure that the UNITED STATES PATENTS two sheets are always spaced apart in the region of the orifice.

137/487 X The device can be employed in combination with the inlet of fluid-flow generating means to control the "251/611 X fluid flow through the inlet.

1.319.154 Johnson.......-..................... 1,934,713 11/1933 Hughes.....

3,485,258 12/1969 Greene 13 Claims, 6 Drawing Figures PATENTED HAY] 51973 SHEET 1 BF 3 IIIIIIIIL 'PATENTEDHAYISIUTS ,888

SHEET 3 OF 3 iiil'lllliiiiiiiiiiiiiiiiiIiiiiiiiiiiiiliiilliliiiil i ww CLOSING DEVICE FOR A PNEUMATIC SYSTEM The present invention relates to closing devices for a pneumatic system comprising expansible means having a deformable wall at one end of which means there is provided a closing face adapted to co-operate with an annular seatadjacent an aperture communicating with I 673,497 in its application to a non-return valve. This known device employs as expansible means a bellows having a corrugated metal wall which has the drawback of possessing a certain amount of stiffness due to its own elasticity Which reduces its sensitivity to effects of variation in the pressure in the chamber of the bellows, since, in order to ensure the closureof the non-return valve, the applied pressure must first overcome the elastic force of the bellows. Moreover, the closing face is defined by a rigid plate so that a precise machining of the valve seat is requiredto achieve the desired closure in the expanded position of the bellows.

, An object of the present invention is to' overcome these drawbacks.

Theinvention provides a closing device for a pneumatic system of the aforementioned'type, wherein the expansible means comprises a preferably circular bag or bladder whose wall is defined by two fluidtight, sheets, for example of coated fabric, which are interconnected in edge to edge manner along their peripheries and in which are provided means, for example in the formof ribs, for separating the two sheets at least in the region of said orifice.

Owing to the fact that its wall is constituted by flexible sheets, the expansible means has no stiffness in the axial direction of expansion or contraction so that it possesses very high sensitivity enabling it to respond to a pressure variation of the-order of a gram per square centimeter.

In the radial direction, the bag has on the other hand 7 a certain stiffness owing to the edge-to-edge assembly of the sheets, this stiffness being if desired reinforced by an inner connecting strip folded in the shape of a V so that even in the deflated condition, the bag retains its initial shape which is, asa rule, circular.

It is advantageous to arrange that the closing face cooperating with the seat be formed directly on one of the sheets of the bag so as to enable it to marry up, by deformation, with the exact shape of the seat which can then be constructed with no particular precautions. Any possible out-of-plane of the seat is therefore of no consequence as concerns the sealing qualities in the closing position.

Such a device can have various applications and in particular can be employed as a non-return valve in a system including a fan, or like pressurized air generator, the expansible bag being subjected externally to atmospheric pressure. In this application, the orifice of the expansible bag communicates with the interior of the inlet pipe, controlled by the closing face, and is so disposed that it receives the prevailing pressure immediately upstream of the fan. Consequently, when the fan starts up, the orifice is subjected to a depression which is transmitted to the interior of the bag and this produces a flattening of the bag leaving free a radial passage of air which thus enters the pipe and is drawn in by the fan.

On the other hand, when the fan is inoperative, the flowing back of air under pressure which occurs through the vanes of the fan creates an overpressure in the orifice which, when acting inside the bag, creates a force exceeding the opposing force produced by the atmospheric pressure so that the active annular portion of the bag is applied on its seat and cuts off any communication between the pipe and the atmosphere.

The closing device according to the invention is also of utility as an overpressure or relief valve.

- The closing device and two applications of this device will now be described with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic view of the closing device having an expansible bag, employed as a non-return valve upstream of a fan and shown in the closing positron;

FIG. 2 is a view of the closing device shown in FIG. 1 in the position corresponding to operation of the-fan, with the closing device in the opening position;

FIG. 3 is a plan view of the bagemployed in the device shown in FIG. 1;

FIG. 4 is a radial sectional view of the bag;

FIG. 5 is a diagrammatic view of the closing device employed as an overpressure or relief valve, and

FIG. 6 is an elevational view of a ring of the device constituting a seat for the closing bag.

FIG. 1 shows a fan whose case 1 contains a rotor 2, which has a horizontal axis of rotation and driven by a motor 3. Entry of exterior air into the fan occurs through an axial aperture 4 in which the flow of air from the exterior is controlled by a closing device 6 including a pipe 7 connected by flanges 8 to the inlet aperture 4. The air under pressure is delivered by way of a tangential aperture 9.

At its end opposed to the flanges 8, the pipe 7 is provided with a flat ring 1 l constituting a collar which constitutes aseat for a closing member 12 consisting of a circular bag or bladder of rubberized fabric of which the face 13 is fixed to a circular plate 14 parallel to the flat ring'l'l and maintained at a constant distance from the latter by spacer members 16. The face or side 15 of the bag which is opposed to the face 13 may be. provided, if desired, with a metal sheet 17 adapted to bear, when the closing member is in the closing position, against a flexible sealingring 18 fixed to the flat ring 1 1 around the pipe 7.

The plate 14 and the upstream face 13 of the bag have in their center an orifice in which is fixed the end 19 of a flexible pipe or conduit 21 which for example comprises a corrugated casing and whose other end 22 extends radially, in a fluidtight manner, through the pipe 7 and opens onto the downstream face of a deflector 24 by way of an orifice 23. The deflector has a frustoconical shape'of which the large end 26, adjacent the closing bag 12, is connected to the inner face of the pipe 7, thesmall end 27 being adjacent the flanges 8 and the inlet aperture 4 of the fan.

In the illustrated position, which corresponds to the state of rest or inoperative state of the fan, the bag (possibly provided with the sheet 17) is applied against the sealing ring 18, since the pressure P, which prevails downstream of the outlet 9 of the fan and is normally higher than atmospheric pressure, exerts on the downstream face of the bag 12, by way of the pipe 7 and the pipe 21, a force exceeding the, force due to atmospheric pressure which is established owing to the fact that the space between the plate 14 and the flat ring 1 1 is open at its periphery to the exterior medium.

When the motor 3 is started up to drive the rotor 2 of the fan, suction, shown by the arrow f, in FIG. 2, is produced in the pipe 7 so that the pressure P which is established downstream'of the deflector 24 is lower than atmospheric pressure, itself lower than the initial pressure P,.

The suction thus produced in the orifice 23 is transmitted by way of the pipe 21 to the interior of the bag 12 so that, under the effect of atmospheric pressure applied to the exterior of the bag on the downstream face 15, the bag is axially crushed and the sheet 17 moves away from the sealing ring 18. The closing device is thus in the opening position and the exterior air flows radially between the flat ring 11 and the crushed bag 12, as indicated by the arrows f It will be understood that the annular section of the passage thus created must be at least equal to the section of the pipe 7.

' The opening of the closing device therefore affords the fan the supply of air required for its operation.

When the fan is stopped, the overpressure prevailing downstream of the fan results in a counterflow in the opposite direction to the flowf and this creates a pressure P on the downstream face of the deflector 24 which is higher than atmospheric pressure and is transmitted by way of the pipe 21 to the interior of the bag 12. The latter is consequently inflated and is applied,

possibly through the medium of the sheet 17, against the sealing ring 18 so that the closing device closes the pipe 17 and stops the air flow. The pressure P then becomes equal to the pressure P, prevailing inside the fan and inside the system downstream of the fan. I

The satisfactory operation of the bag 12 implies that the latter is very easily deformable in the axial direction so as to expand or'contract under the effect of pressure variations. It is, on the other hand, desirable that this bag have great stiffness in the radial direction. These two conditions are satisfied in the embodiment shown in FIGS. 3 and 4 in which the bag 12 is constituted by two sheets of rubberized

fabric

31, 32 whose two edges are interconnected by vulcanization which produces a peripheral lip portion 33, this connection being completed by an inner strip 34 which is folded to have a Y- section' and whose two branches are connected to the inner faces of the

walls

31, 32 respectively, in a position adjacent the lip portion 33. These two branches define an extremely small included angle.

Further, the wall 32, which corresponds to the downstream face 15 shown in FIG. 1, is provided with ribs 36 arranged in the manner of a star (FIG. 3). They are preferably section members having a rectangular crosssection and are composed of rubberized fabric or rubber and constitute suction collectors which permit, when the bag is subjected to suction, drawing out all the air contained in the bag while precluding the closure of the axial orifice 37 of the bag by the wall 32 which wou'ldbe otherwise placed flat against this orifice. These ribs also serve to stiffen the bag radially.

FIG. 5 shows a closing device 46 having a bag or bladder 12 and generally conforming to that shown in FIGS. 1 and 2 but adapted to be employed as a relief valve or overpressure valve to maintain constant the pressure prevailing in a pneumatic system which communicates with the pipe 7 by way of a pipe 47.

Instead of the flexible pipe 21 which directly connects the orifice 23 of the deflector 24 to the center orifice 37 of the bag 12, there is provided a flexible pipe or conduit 48 which is connected firstly by a coupling 49 to a calibrated exhaust valve 51 and, secondly, to the orifice 23 by way of a pipe or conduit 45. The calibrated valve 51 comprises a circular seat 52 constituting the end orifice of the pipe 50 connected to the coupling 49. This orifice is normally covered or masked by the flat end 53 of a closing weight 54 which is slidable in a cup 56 whose lower end has a lateral exhaust pipe 57 located at the level of the seat 52. The pipe 45 connecting the coupling 49 to the orifice 23 of the deflector 24 comprises a calibrated washer 58 which forms brake or retarding means for the air flow and tends to create a preferential flow path through the flexible pipe 48 between the pneumatic system, to which the pipe 47 is connected, and the calibrated valve 51 while permitting a pressure balance. To facilitate the escape of air in the event of overpressure, a series of orifices 61 arranged on a circle are provided in the flat ring 11 at a radial distance from the sealing ring 18.

Assuming the closing device is in its closing position, as shown, with the bag 12 applied against the sealing ring 18, there prevails inside the pneumatic system, the pipe '47 and the bag'l2, a pressure P exceeding atmospheric pressure. (P,,,). The weight 54, which defines the calibration of the valve 51, defines a pressure P so that P P P The closing device remains closed when the pressure P varies within the limits P and P If the pressure of the system P reaches and exceeds P the closing weight 54 is raised so that there is a slight escape of air through the orifice 52 and the pipe 57 of the valve 51 and the bag 12 deflates. The face 15 of the bag adjacent the pipe 7 then moves away from its seat and the air is able to escape by way of the orifices 61 in the flat ring 1 1. This escape of air contributes to lower the pressure P which, at the moment it reaches a value slightly lower than pressure P for which the valve 51 is calibrated, causes the weight 54 to descend and close the orifice 52 then brings about, by way of the pipe 45 and the calibrated orifice 58, an increase in the pressure in the bag 12 which once more bears against its seat and consequently puts the closing device in its closing positron.

The rate of flow through the valve 51'is very low, since it essentially results from the deflation of the bag 12. By adopting a suitable section for the pipe 7, a very high exhaust flow rate can be achieved, that is to say, a rapid return of the pneumatic system to the reference or imposed value of the pressure.

The sensitivity of the response is excellent, since there is neither risk of wedging nor any problem of inertia. The device is capable of operating in any position provided the valve 51 is correctly designed to permit this.

Having nowdescribed our inventionwhat We claim as new and desire to secure by Letters Patent is:

l. A closing device for a pneumatic system comprising expansible means having a deformable wall, a closing face provided at one end of the expansible means, means defining an annular seat, means defining an aperture surrounded by the annular seat, passage means for connecting the aperture to the pneumatic system, the closing face being co-operable with the annular seat, the wall of the expansible means defining an inner chamber and the wall having an orifice, conduit means for connecting the orifice to the passage means so that pressure variations in the chamber result in the selective contraction and expansion of the expansible means and a relative displacement of the seat and the closing face which selectively unmasks and closes said annular seat, the expansible means being a flexible bag, said wall comprising two fluidtight sheets having interconnected peripheral portions and means for ensuring that the sheets are always spaced apart in the region of said orifice.

2. A closing device as claimed in claim 1, wherein the bag is circular.

3. A closing device as claimed in claim 1, wherein the sheets are of coated fabric.

4. A closing device as claimed in claim 1, wherein said means ensuring that the sheets are always spaced apart in the region of the orifice comprise ribs on the deformable wall.

5. A device as claimed in claim 1, comprising a connecting strip having a V-sectional shape defining two branches which are respectively connected to the sheets inside the bag immediately adjacent the interconnected peripheral portions of the two sheets.

6. A device as claimed in claim 1, wherein the closing face is constituted by one of the sheets of the bag.

7. A device as claimed in claim 1, wherein one of the .sheets of the bag comprises internal ribs of flexible material which extend in the region of said orifice.

8. A device as claimed in claim 1, comprising a deflector of frustoconical shape located inside the passage means, a second orifice in the deflector, said conduit means connecting the orifice of the bag to the second orifice, the convergence of the deflector being in the direction away from the bag and the second orifice communicating with the passage means on the side of the delector remote from the bag.

9. A device as claimed in claim 8, comprising a calibrated valve having a seat defining an intermediate orifice and an exhaust pipe which communicates with the exterior, means putting the intermediate orifice in communication with the orifice of the bag and with the orifice of the deflector, the calibrated valve being capable of putting the interior of the passage means in communication with the exhaust pipe by way of the orifice of the deflector and the intermediate orifice when the pressure inside the passage means exceeds a predetermined value.

10. A device as claimed in claim 9, wherein the means putting the intermediate orifice in communication with the orifice of the deflector and with the bag orifice comprise a conduit having a calibrated orifice and putting the intermediate orifice in communication with the deflector orifice.

11. A device as claimed in claim 9, wherein the means defining the seat comprises a ring having a series of orifices communicating with the exterior and capable of being unmasked by the closing face when the bag deflates so as to achieve, when there is an excess of pressure in the passage means, an escape of fluid from the passage means and a pressure relief.

12. A structure comprising in combination fluid-flow generating means having an axial inlet, a closing device for the inlet comprising expansible means having a deformable wall, a closing face provided at one end of the expansible means, means defining an annular seat, means defining an aperture surrounded by the annular seat, passage means for connecting the aperture to the inlet, the closing face being co-operable with the annular seat, the wall of the expansible means defining an inner chamber and the wall having an orifice, conduit means for connecting the orifice to the passage means so that pressure variations in the chamber result in the selective contraction and expansion of the expansible means and a relative displacement of the seat and the closing face which selectively unmasks and closes said annular seat, the expansible means being a flexible bag, said wall comprising two fluidtight sheets having interconnected peripheral portions and means for ensuring that the sheets are always spaced apart in the region of said orifice, the conduit means opening into the passage means in a direction which enables the conduit means to be exposed to the pressure which is established immediately upstream of the inlet of the fluidflow generating means.

13. A structure as claimed in claim 12, comprising an annular deflector which is secured to an inner face of the passage means and has a shape converging toward the inlet of the fluid-flow generating means, the conduit means having an orifice which is opposed to the bag orifice and opens onto a face of the deflector adjacent the inlet.

Claims

1. A closing device for a pneumatic system comprising expansible means having a deformable wall, a closing face provided at one end of the expansible means, means defining an annular seat, means defining an aperture surrounded by the annular seat, passage means for connecting the aperture to the pneumatic system, the closing face being co-operable with the annular seat, the wall of the expansible means defining an inner chamber and the wall having an orifice, conduit means for connecting the orifice to the passage means so that pressure variations in the chambEr result in the selective contraction and expansion of the expansible means and a relative displacement of the seat and the closing face which selectively unmasks and closes said annular seat, the expansible means being a flexible bag, said wall comprising two fluidtight sheets having interconnected peripheral portions and means for ensuring that the sheets are always spaced apart in the region of said orifice.

2. A closing device as claimed in claim 1, wherein the bag is circular.

7. A device as claimed in claim 1, wherein one of the sheets of the bag comprises internal ribs of flexible material which extend in the region of said orifice.

12. A structure comprising in combination fluid-flow generating means having an axial inlet, a closing device for the inlet comprising expansible means having a deformable wall, a closing face provided at one end of the expansible means, means defining an annular seat, means defining an aperture surrounded by the annular seat, passage means for connecting the aperture to the inlet, the closing face being co-operable with the annular seat, the wall of the expansible means defining an inner chamber and the wall having an orifice, conduit means for connecting the orifice to the passage means so that pressure variations in the chamber result in the selective contraction and expansion of the expansible means and a relative displacement of the seat and the closing face which selectively unmasks and closes said annular seat, the expansible means being a flexible bag, said wall comprising two fluidtight sheets having interconnected peripheral portions and means for ensuring that the sheets are always spaced apart in the region of said orifice, the conduit means opening into the passage means in a direction which enables The conduit means to be exposed to the pressure which is established immediately upstream of the inlet of the fluid-flow generating means.