WO2005095831A1

WO2005095831A1 - Valve

Info

Publication number: WO2005095831A1
Application number: PCT/EP2005/003480
Authority: WO
Inventors: Enso Papi
Original assignee: Tm.C. S.P.A. Termomeccanica Compressori
Priority date: 2004-03-30
Filing date: 2005-03-29
Publication date: 2005-10-13
Also published as: ITMI20040622A1

Abstract

A control valve (10, 110, 210, 310) comprising a base body (12, 112, 212, 312) on which a shutter (14, 114, 214, 314) is fitted able to run in relation to the base body (12, 112, 212, 312) by means of drive elements to close an aperture (16, 116, 216, 316) coupling with a surface (38, 138, 238, 338) of a hollow cover (20, 120, 220, 320) connected to the base body (12, 112, 212, 312) by means of locking elements, said valve (10, 110, 210, 310), at least one of said components being made of plastic.

Description

VALVE

The present invention refers to a low cost control valve . The term valve identifies all fluid flow regulation devices; as is immediately evident, this first definition is general and the concept in question covers a wide range of practical embodiments present in various application fields, often completely different from each other given the large number of variables involved. Examples of these variables are: pressure, type of fluid, fluid speed and temperature, without considering the surrounding conditions, for example cleanliness, presence of corrosive agents etc. In particular, the present invention refers to a specific sector having the following characteristics: gaseous fluid under pressure, pressures between 1 and 30 bars, operating temperatures below 150°C. The technical aspects and problems of said specific sector must be taken into account .

At present almost all the components of these control valves are generally made of metal . The metal alloys used are well-known and guarantee correct operation of the valves subject to the stress resulting from the conditions of use.

Use of the known metal alloys has some drawbacks, however, in addition to the cost of the metal specifically developed for said applications.

Some of these problems are connected with the final weight of the valve and the difficulty of using it in the presence of chemical compounds otherwise corrosive to metals. The aim of the present invention is therefore to remedy the drawbacks previously mentioned and in particular to produce a low cost control valve with limited weight and low reactivity to chemical agents . A further aim of the present invention is to produce a low cost control valve with low inertia, responding promptly to commands.

A further aim of the present invention is to produce a low cost control valve with a drastic reduction in wear, with consequent longer life and greater dependability.

A further aim of the present invention is to produce a particularly simple and functional low cost control valve . These and other aims according to the present invention are achieved by producing a low cost control valve as described in claim 1.

Further characteristics are illustrated in the subsequent claims.

The characteristics and advantages of a low cost control valve according to the present invention will become clearer from the following description which is provided as a non-limiting example, referring to the attached schematic drawings in which: figure 1 is a side elevation section of a first embodiment of the low cost control valve according to the present invention; figure 2 is a front elevation section of a second embodiment of a low cost control valve according to the present invention; figure 3 is a front elevation section of a third embodiment of a low cost control valve according to the present invention; figure 4 is a front elevation section of a fourth embodiment of a low cost control valve according to the present invention.

With reference to figure 1, a low cost control valve is shown, indicated overall by 10. The valve 10 comprises a base body 12, in which a shutter 14 operates, generally sliding in one direction. The shutter 14 operates as a closing element on an aperture 16 for passage of fluid provided in a cover 20 which is coupled to said base body 12 by means of locking elements, and is coaxial with the shutter 14.

The base body 12 is a body having, starting from a first connection end for a compressor, a base surface 90 of a first portion 25 having a lateral surface 19, and a second portion with smaller external diameter 27 which forms with the first portion 25 a surface 29 in the form of a circular crown. The second portion 27 of the base body 12 has a cylindrical outer surface 11 and a base surface 22 at a second end of the base body 12 in which a central C-shaped aperture 18 is provided defining a central hollow cylindrical element 24, protruding with respect to said surface 22 and connected to the base body via a portion 21. The hollow cylinder 24 has at one end a cylindrical portion having an outer surface 28 on which the shutter 14 is inserted, and a base surface 31 in which a hole 30 is obtained which is connected to a hole 23 made on the lateral surface 19 of the base body 12 corresponding to the first portion 21.

The shutter 14 is a plug having a head 34 and a cylindrical stem 32 with a blind hole that comprises a bottom surface 35 and a cylindrical lateral surface 26 which couples with the outer surface 28 of the hollow cylindrical element 24 of the base body 12 and is able to run in an axial direction with respect to it. Inside the hole 30 of the hollow cylindrical element 24 elastic elements are inserted which, cooperating with pressurised air introduced into the hole 23 and passing into the shutter 14, press on the bottom surface 35 so that the shutter 14 runs axially with respect to the base body 12, moving it away from the base surface 22 of the base body 12 and closing the aperture 16 of the cover 20, consequently preventing the passage of fluid also towards the aperture 18 of the base body 12. The head 34 of the shutter 14 has an outer surface 36 which, by coupling with a surface 38 of the cover 20, preferably annular, provides a seal, keeping the aperture 16 of the cover 20 closed.

The head 34 of the shutter is also provided with a small central through hole 40 via which a small amount of the pressurised air introduced into the hole 23 is discharged. During operation of the valve the pressurised air flow via this central through hole 40 stabilises the shutter 14 preventing vibrations of the same and improving overall operation of the valve. The cover 20 is a tubular body having, starting from a first end, a first portion 50 in the shape of a flange which houses locking elements followed by a second cylindrical annular portion 52 with smaller external diameter, a third tapered annular portion 54 and lastly a fourth cylindrical annular portion 56 with smaller diameter. The first portion 50 has a cylindrical inner surface 39 with constant section which couples with a corresponding cylindrical surface 11 of the base body 12. The first portion 50 has a base surface 51 in the shape of a circular crown which couples with the corresponding surface 29 in the shape of a circular crown of the first portion of the base body 12. Furthermore the first portion 50 of the cover 20 has, at the level of a second cylindrical annular portion 52, a base surface 91 in which through holes 61 are obtained.

The locking elements have the function of making the cover 20 integral with the base body 12. In this first embodiment the locking elements preferably comprise threaded holes 63, obtained in the base surface 29 of the first portion 25 of the base body 12, and screws 62 inserted in the through holes 61 of the cover 20 and screwed in the threaded holes 63 to make the base body 12 and the cover 20 integral. The second cylindrical annular portion 52 of the cover

20 has an inner surface and a cylindrical outer surface. The third tapered annular portion 54 has an inner surface 38 which couples with the outer surface

36 of the head 34 of the shutter 14, closing the aperture 16 defined in the fourth cylindrical annular portion 56 of the inner cylindrical surface 57.

The shutter 14 in the rest position is pressed against the cover 20 by elastic elements inserted inside the base body 12, which operate inside the shutter 14. Via the hole 23 the intake of pressurised air can be suspended so that, by operating a compressor connected to the base surface 90 of the first portion 25 of the base body 12, it is possible to suck a fluid from the aperture 16 of the cover 20 as far as the compressor via the aperture 18 of the base body 12.

To maintain the seal the base body is also provided with a gasket 17 inserted in the first portion 25 of the base body 12 protruding from the surface 29 and in contact with the circular crown shaped surface 51 of the cover 20.

Figures 2, 3 and 4 illustrate further possible practical embodiments of the invention, where the components equal and/or equivalent to those illustrated in figures 2, 3 and 4 have the same reference numbers increased by 100 or 200 or 300. Figure 2 shows a second embodiment of the present invention illustrating a cover 120 connected to a base body 112 preferably by means of a bayonet fitting. The first portion 150 of the cover 120 has an inner cylindrical surface 39 having a protruding element 65 which, by rotation of the cover 120 inserted on the base body 112, can be pressed into a corresponding element 64 protruding from the outer cylindrical surface 11 of the second portion 127 of the base body 112, preventing the relative sliding movement and making the cover 120 and base body 112 integral. In this second embodiment the locking elements comprise preferably the element 65 protruding from the inner cylindrical surface 39 of the first portion 150 of the cover 120 and the element 64 protruding from the outer cylindrical surface 11 of the second portion 127 of the base body 112.

Figure 3 shows a third embodiment of the present invention illustrating a cover 220 connected to a base body 212 by means of a threaded fitting.

In this third embodiment the locking means comprise preferably a threaded inner cylindrical surface 66 obtained in the first portion 250 of the cover 220 and a corresponding threaded outer cylindrical surface 67, which can be screwed to it, obtained on the second portion 227 of the base body 212, in order to connect the base body 212 to the cover 220.

Figure 4 shows a fourth embodiment of the present invention illustrating metal inserts present in the base body 312 and in the shutter 314.

In this fourth embodiment of the present invention, there is a hollow cylindrical bronze metal insert 68 inserted on the inner surface 326 of the cylindrical stem 332 of the shutter 314 which couples with a corresponding hollow cylindrical metal insert 70 inserted in the central hollow cylindrical element 324 of the base body 312.

There is also a metal insert in the shape of a plate in the base surface 390 of the base body 312 for accurate coupling with a compressor, for example. Lastly, in this embodiment the locking elements comprise, instead of the threaded holes 63, inserted threaded metal inserts 72 which couple with the screws 362 for improved coupling and which are inserted in the base surface 329 of the base body 312.

According to the present invention, the valve 10 is made of plastic. In particular, the components of the valve 10 are made entirely or almost entirely of plastic.

Naturally there are also non-plastic items, such as screws and gaskets which, moreover, do not constitute critical elements for correct operation of the valve 10. The use of plastic permits considerable reduction in cost and weight of the control valve. If for example the valve is a suction valve in a screw compressor, the cost and weight of the screw compressor itself, on which the valve is fitted, are drastically reduced. Another important factor deriving from the lightness of the plastic components is the low inertia of the same when subjected to variable force. This concerns in particular the moving elements, i.e. the shutter 14: by producing it in plastic, there is an increase in the response speed, an aspect which in particular applications constitutes a considerable functional advantage .

Another factor of the plastic components is the low level of friction which results in a drastic reduction in wear with consequent longer life and greater dependability.

In addition, the very high chemical stability of the plastic makes the valve 10 of the invention suitable for use in the presence of chemical compounds otherwise corrosive to metals.

The components can be made of a plastic with optimal mechanical characteristics to withstand the pressures of the pressurised fluid when the valve is closed. The plastic comprises a reinforced polymer, or more preferably a reinforced technopolymer with optimal mechanical characteristics and high resistance to chemical agents .

The term technopolymer indicates a polymer chosen from a polyketone, a polysulphone, a polyphenylether or their mixtures .

Even more preferably the reinforced technopolymer is a reinforced polyketone . Production using a plastic material also constitutes a further important aspect of the present invention. As the components of the valve 10 are made of moulded plastic material, it is possible and expedient to provide inserts of different material in various critical points of the valve 10. Said inserts are generally made of metal . The use of inserts allows you to choose the material to be used not on the basis of the stress of the valve 10 analysed globally, which inevitably leads to compromises between costs and benefits, with consequent reduced performance as regards both duration and resistance, but on the basis of the individual specific local requirements of the valve 10. The result is that the valve 10 is no longer studied as such in its entirety but is seen as a set of sub-systems which can, with the present invention, be managed and studied in a completely separate and therefore much more efficient way. It should be noted that a very important aspect when talking about mechanical components which, like valves, will constitute an essential element of a more complex machine, is ease of maintenance. The configuration of the valve 10 has been designed with this factor in mind; at least two extremely important aspects can be noted from the point of view of maintenance : - possibility of performing all types of maintenance (replacement of the internal elements or simply cleaning) without having to physically disassemble the whole component from the installation; - extremely rapid access to the internal parts of the component with base connection which can be screw type, threaded type or bayonet type .

From the description provided, the characteristics of the low cost control valve subject of the present invention are clear, as are the related advantages. Lastly it is clear that the low cost control valve thus conceived can be modified and varied in numerous ways, all falling within the invention; in addition all the parts can be replaced by technically equivalent parts. In practice any materials, shapes and dimensions can be used, according to technical requirements.

The protective scope of the invention is therefore defined by the attached claims.

Claims

1. Control valve (10, 110, 210, 310) comprising a base body (12, 112, 212, 312) on which a shutter (14, 114, 214, 314) is fitted able to run in relation to the base body (12, 112, 212, 312) by means of drive elements to close an aperture (16, 116, 216, 316) coupling with a surface (38, 138, 238, 338) of a hollow cover (20, 120, 220, 320) connected to the base body (12, 112, 212, 312) by means of locking elements, said valve (10, 110, 210, 310), at least one of said components being made of plastic.

2. Control valve as claimed in claim 1, characterised in that all the components are made of plastic.

3. Control valve as claimed in claim 1, characterised in that the locking elements comprise screws (62) inserted in through holes (61) obtained in the cover

(20, 120, 220, 320) and screwed in threaded holes (63) obtained in the base body (12, 112, 212, 312) to connect the cover (20, 120, 220, 320) to the base body (12, 112, 212, 312) .

4. Control valve as claimed in claim 1, characterised in that the locking elements comprise a bayonet fitting to connect the cover (20, 120, 220, 320) to the base body (12, 112, 212, 312) .

5. Control valve as claimed in claim 1, characterised in that the locking elements comprise a threaded surface (66) obtained in the cover (20, 120, 220, 320) and screwed to a corresponding threaded surface (67) obtained in the base body (12, 112, 212, 312) to connect the cover (20, 120, 220, 320) to the base body (12, 112, 212, 312) .

6. Control valve as claimed in claim 1, characterised in that it comprises metal inserts.

7. Control valve as claimed in claim 1, characterised in that the metal inserts comprise a hollow cylindrical metal insert (68) inserted inside a cylindrical stem

(32, 132, 232, 332) of the shutter (14, 114, 214, 314) which couples with a corresponding hollow cylindrical metal insert (70) inserted on a central hollow cylindrical element (24, 124, 224, 324) of the base body (12, 112, 212, 312) to minimise the friction, and furthermore a metal insert in the form of a plate inserted on a base surface (90, 190, 290, 390) of the base body (12, 112, 212, 312) for improved coupling with a compressor and furthermore threaded metal inserts (72) inserted in the base body (12, 112, 212, 312) which couple with screws (62, 162, 262, 362) for improved coupling and which are inserted in the base surface (29) of the base body (12, 112, 212, 312).

8. Control valve as claimed in claim 1, characterised in that the plastic comprises a reinforced polymer with optimal mechanical characteristics and high resistance to chemical agents .

9. Control valve as claimed in claim 8, characterised in that the reinforced polymer is chosen from a polyketone, a polysulphone, a polyphenylether and their mixtures.

10. Control valve as claimed in claim 9, characterised in that the reinforced polymer is chosen from a reinforced polyketone.

11. Control valve as claimed in claim 1, characterised in that the shutter (14, 114, 214, 314) comprises a drilled cylindrical stem (32, 132, 232, 332) and a head (34, 134, 234, 334) in which a central through hole is made (40, 140, 240, 340) of reduced dimensions, and characterised in that the drive elements comprise pressurised air which passes into the shutter (14, 114, 214, 314) and comes out through said central through hole (40, 140, 240, 340) to stabilise the shutter (14, 114, 214, 314) and prevent vibrations during operation of the valve .

12. Control valve according to claims 1-11, characterised in that it comprises gaskets to maintain a hermetic seal and an external filter fitted on the cover (20, 120, 220, 320) for the fluid.

13. Control valve as claimed in claim 1, characterised in that it is a control valve (10, 110, 210, 310) for a gaseous pressurised fluid, with pressures of between 1 and 30 bars and operating temperatures below 150 °C.