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Title:
A MINIMUM PRESSURE VALVE AND COMPRESSOR COMPRISING SUCH A MINIMUM PRESSURE VALVE
Document Type and Number:
WIPO Patent Application WO/2019/008451
Kind Code:
A1
Abstract:
The present invention is directed to a minimum pressure valve comprising a housing (13) with a. valve inlet (11) and a valve outlet (12) which are connected by means of a chamber (16), said minimum pressure valve (105 further comprising a valve body (17) movable in said chamber {16; between a closed position in which said valve inlet (11) is closed off, and an open position in which said valve inlet (II) is open, whereby said minimum pressure valve (10) further comprises a regulation unit (18) for setting the value of the pressure at which the valve body (1?) mena3 into an open position.

Inventors:
DE SCHAMPHELAERE, Pieter (nvBoomsesteenweg 957, 2610 Wilrijk, 2610, BE)
Application Number:
IB2018/053673
Publication Date:
January 10, 2019
Filing Date:
May 24, 2018
Export Citation:
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Assignee:
ATLAS COPCO AIRPOWER, NAAMLOZE VENNOOTSCHAP (Boomsesteenweg 957, 2610 Wilrijk, 2610, BE)
International Classes:
F04B49/03
Foreign References:
US1587015A1926-06-01
US20130139535A12013-06-06
US1706373A1929-03-19
US20130000759A12013-01-03
US5540558A1996-07-30
GB1597718A1981-09-09
US1798435A1931-03-31
GB2234801A1991-02-13
Attorney, Agent or Firm:
VAN VARENBERG, Patrick et al. (Arenbergstraat 13, 2000 Antwerpen, 2000, BE)
Download PDF:
Claims:
Claims .

1 À minimum pressure vai-ve comprising a housing (13) with a val-ve inlet (11) and a valve outlet (12) which are connected by means of a chamber (16), said minimum pressure valve (10) further comprising a valve body (17) movabLe in said chamber (16) betrreen a closed position in which said valve inlet (11) is closed off, and an open position in which said valve inlet (1f) is open, characterized in that said mj-nimum prèssure valve (10) further comprises a regulation unit (18) for setting the vaLue of the pressure at which the valve body (17) moves into an open position.

2. Minimum pressure valve according to claim L, characterized in that the minimum pressure va Ive (10 ) does not cornprise a spring.

3. Minimum pressurè valve according to any one or more of the previous claims, characterized in that the regulation unit (18) comprises a conduj-t (19) fluidly connecting a space (20') delimited betlreen the valve body (17) and the chamber (16) with the valve inl-et (11).

4. Minimum pressure vafve according to c.Iaim 3, characterized in that the regulation unit (18) cornprises a restricting module 122) adapted to be connected on the one hand to the conduit (19) and on the other hand onto a channel 123) created through the housing (13) and a r^ra.l- 1 of the chamber (16) . 5. pressure valve according to cfaim 4, characterized in that the restricting modufe 122') comprises a screw for adapting the flow of fluid fLowing through said channel (23) . 6. Minimum pressure val,ve according to any one or more of the previous claims, characterized j-n that the valve body (17) comprises a piston (24) recej-ved therein movabl-e bet$reen a closed position in which the valve inlet (11) is closed off and an open position in which said valve inlet (11) is open. 7. Minimum pressure val-ve according to cfaim 6 characterized in that when mounted, saj-d minimum pressure valve (10) does not comprise a spring between the val-ve body (17) and the piston (24).

8. Minimum pressure valve according to any one or more of the prevj-ous claims, characterized in that the valve body (17) comprises a seal (28) adapted to be mounted on the outer contour of the valve body (17), bet$reen the valve body (17) and the internal wall- of the chamber (16).

9. Minimum pressure valve according to any one or more of the previous claims, characterized in that the valve body (17) comprises a guiding unit (29) adapted to be mounted on the outer contour of the valve body (17), between the valve body (17) and the chamber (15).

10. Minimum pressure valve according to claims 8 and 9, characterized in that the seal (28) is received in between two guiding units (29) .

11. Minimum pressure valve according to any one or more of the previous claims, characterized in that the chamber (16) comprises a groove (30) above a first end (17a) of said valve body (L7\, the first end (17a) being closest to the valve outleL (12).

12. Minimum pressure valve according to claim 4, characterized in that at the 1evel of the channel- 123) the valve body (17) comprises a carved sect.ion (31) .

13. Minimum pressure valve according to claj-m 12, characterj.zed in that the carved sectj-on (31) has a height equal to the stroke of the valve.

74. Minimum pressure valve according to c]-aj.m 12 or 13, characterized in that the guiding unit (291 comprises a first guiding tape mounted on the outer contour of the valve body (1'l) , between the carved section (31) and a first end (L7a) of sald valve body (17), the first end (17a) being closest to the valve outlet (12 ) .

15. Minj-mum pressure val-ve according to any of the claj-ms \2 to 14, characterized in that the guiding unit (29) further comprises a second guiding tape mounted on the outer contour of the valve body (17), between the carved section (31) and a second end (17b) of said valve body (17), said second end (17b) belng closest to the valve inlet (11) .

16. Minimum pressure valve according to claims 4 and 11, characterized in that the channel (23) is fluidly connecting the space delimited by the groove (30) with the valve inlet (11).

l'7. Minimum pressure valve according to claim 6, characterj-zed in that the piston (241 comprises a semi-circufar step section, said semi-circular step section being adapted to be brought in contact with the housing (13).

18. Minimum pressure valve according to c.Iaim 6, characterized in that the piston 124) comprises a second guiding unit (34) adapted to be mounted between the piston (24) and the valve body (17).

19. Minimum pressure valve according to c.l-aim 11, characterized in that a top space (35) is created between the chamber (16) and the first end (17a) of the val-ve body ( 17 ) .

20. A compressor comprisinll a compressor element (2) having a gas inlet (3) and a compressed gas outlet (4), the compressor (1) further comprising a pressure vessel- (6) having an inlet (7) connected to the compressed gas outlet (4), whereby a minimum pressure valve (10) is provided at an outLet (8) of said pressure vessel (6), said minimum pressure valve (l-0) having a va.Lve inlet (11) connected to the outl-et (8) of the pressure vessel (5) and a valve outlet lL2]. adapted to be connected to a user's network (91 , whereby said minimum pressure valve (10) comprises a housing (13) whereby the valve inlet (11) and the val-ve outleL (12) are connected by means of a chamber (16), a vaJ-ve body (17) movable in said chamber (16) bethreen a closed position in which said valve inlet (11) is closed off, and an open position in which said valve j-nlet (11) is open, characterized in that said minimum pressure val-ve (10) further comprises a regul-ation unit (18) for setting the val-ue of the pressure at which the valve body (17) moves into an open position.

2L. Compressor according to clai-m 21, characterized in that the compressor (1) 1s a liquid inj ected compressor.

22. Compressor according to claim 2L or 22, characterized in that the compres sor (1) oi1 inj ected.

23. Compressor according to any onè or more of claims 2L Eo 23, characterized in that the regulation unit (18) comprises a conduit (19) connecting a space l20l del,imited between the valve body (17) and the chamber (16) with an outfet (8) of the pressure vesseL (6) .

24. Compressor according to any one or more of claims 2l Eo 24, characterized in that the compressor (1) further comprises an oil separation element (21-) provided on the outl-et (8) of the pressure vessel (6) , betÍ4reen the pressure vesse.I ( 6) and the minimum pressure valve (1-0 ) .

25. Compressor according to claim 24 and 25, characterized in that the conduit (19) connects the space (20) del-imited between the valve body (17) and the chamber (16) with the outlet (8) of the pressure vessel (6), before the oif separation element (21). 26. Method foï regulating the pressure in a pressure vessel (6) of a compressor (1), whereby the compressor (l-) further comprises a compressor e.Iement 12) having a gas inlet (3) and a compressed gas outlet (41 , whereby the pressure vessel (6) has an inlet (7) connected to the compressed gas outlet (4), $rhereby a minj,mum pressure valve (1"0) is provided at an outlet (8) of said pressure vessel (6), said minimum pressure val-ve (10) having a valve inlet (11) connected to the outlet (8) of the pressure vessel (6) and a valve outlet (72], adapted to be connected to a user's network (9), whereby said minimum pressure vafve (10) comprises a housing (13) whereby the valve infet (11) and the va]ve outlet lL2) are connected by means of a chamber (16), a valve body (17) movable in said chamber (16) between a closed posj-tion in which said valve inlet (11) is closed off and an open position in which said valve inlet (11) is open, characterized in that for setting the value of the pressure at which the va]ve body (17) moves into an open position, use is made of a regulation unit (18) .

21. Method according to c.l-aim 27, characterized in that the regulating unit (18) uses the pressure at the outfet (8) of the pressure vessef (6) for setting the va.Iue of the pressure at which the valve body (17) moves lnto an open positlon.

28. Method according to claim 21 or 29, characterized in that use is made of a minimum pressure val-ve (10) according to any of the previous claims I to 20.

Description:
A minj-mum pressure valve and compressor comprising such a minimum pressure valve.

This invention relates to a minimum pressure valve comprising a housing lrith a valve inlet and a valve outlet which are connected by means of a chamber, said minimum pressure valve further comprising a valve body movable in said chamber between a closed position in which said vafve infet is closed off, and an open position in which said vaf ve in.Iet is open.

ft is known that compressor instalfations often comprise a minimum pressure val,ve (hereafter abbreviated MPV) , often mounted at the outlet of a pressure vessel, which might serve for the purpose of separatíng liquid, such as oi1 in case of an oil injected compressor, fïom the compressed gas leaving the compressor el-ement.

By injecting a Liquld, such as for example oi.1, into the compressor el-ement of the compressor during the compression of the 9as, the temperature rise of the compressed gas can be kept under controf. The cooling liquid is typíca11y separated from the compressed gas stream in a liquid separator, which often is incorporated into a pressure vesse.l mounted downstream of the compressor element. The cooling liquid is then usually recycled and fed back, from the pressure vessel or liquid separator, through a cooler, to the compressor element. While ffowing through the cooling circui-t, the pressure of the cooling Iiquid will drop. In order to make sure that the pressure of the cooling liquid 1s stil-l sufficiently hiqh in order to be re-injected into the compressor element, the pressure in the pressure vessëI or Iiquid separator needs to be maintained at a sufficientl-y hj-gh l-eve1.

Àn MPV assures that the pressure in the pressure vessel, durlng load of the compressor 1nsta1latj.on, never drops below a determined minimum value. This mininum vafue is the setpoint of the MPV.

The setpoint is chosen such that the j.njection of cooling liquid is always guaranteed, under aIl- conditions. This means that also during transient conditions the pressure htill- be maintained suff ici.entl-y high to avoid temperature peaks. The setpoint is afso chosen in a way that the flow speed through the pressure vessel or liquid separator is not too high.

Such MPVS are used in the industry, like for exampfe the one disclosed in CN 101,520,103 A.

A significant drawback of the known MPVs is that they tend to have a significantly hiqh number of components interacting with each other. This trans.Lates .into a significantl,y high amount of time needed for assembling such a minimum pressure valve on site, which translates into very high maintenance costs and losses associated with the compressor not being functional during this time frame . Moreover, each of the components wiIl have its o&rn tolerance, these individual tolerances adding up and influencing the overaff performance of the mi nimum pressure valve. Eurthermore, because of such a high number of components, during assembl-y some of them, for example the springs woufd require pre-tensioning, can easily damage the adj acent

components entering in contact with such a spring.

Taking the above drawbacks j-nto account it is an object of the present invention to provide a minimum pressure valve that would be easy to manufacture and mount, having a .l-ot fess interacting components and reducing the risk of an incorrect mounting or of an incorrect functioning of the mj-nimum pressure valve after mounting. The present invention aims at providing a minimum pressure vaLve that would be adaptabfe to be used within compressors of different capacities without the need of changing any components. Consequently, the present patent application relates to a new design of minimum pressure valve, which is less prone to hrear and potentia] failure than traditional mj-nimum pressure valves.

To this aim the invention relates to a minimum pressure val-ve comprisJ-ng a housing with a valve inlet and a valve outlet hrhich are connected by means of a chamber, said minimum pressure valve further comprising a valve body movable in said chamber bethÍeen a closed position in which said val-ve inlet is closed off, and an open position in which said valve inlet is open, r^rhereby said minimum pressure valve further comprises a requlation unit for setting the va.Iue of the pressure at which the va.Ive body moves into an open position.

Indeed, because the minimum pressure valve according to the present invention comprises a regul-ation unit, such minimum pressure val-ve can be adapted for any type of compressor without the need of changing specific components.

Another benefit is the minimum number of components that require expensive machinj-ng for such mi-nj-mum pressure va1ve, reducing the costs assocj-ated with manufacturing and maintaining the functionality thereof, and also minimizing if not even eJ-iminating the risk of such minimum pressure valve to have a lower risk to fail- due to a faulty mounting or of damaged components during the mounting procedure. The failing possibly transl-ating into a modified pressure value at which such a minimum pressure valve opens, which would be highly unwanted at the customer' s end. The present invention is further directed to a compressor comprising a compressor element havj-ng a gas infet and a compressed gas outlet, the compressor further comprising a pressure vessel- having an inlet connected to the compressed gas outlet, whereby a minimum pressure valve is provided at an outlet of said pressure vessel, said minimum pressure valve havj-ng a valve inl-et connected to the outl,et of the pressure vessel and a valve outlet adapted to be connected to a user' s net!/ork, whereby said minimum pressure valve comprises a housing whereby the vafve inlet and the vafve outlet are connected by means of a chamber, a valve body movable in said chamber between a closed position in which said val-ve inlet is closed off, and an open position in which said valve inlet is open, whereby said minimum pressure valve further comprises a regufatj,on unit for setting the value of the pressure at which the valve body moves into an open position.

The invention also relates to a method for regulating the pressure j-n a pressure vessel of a compressor, whereby the compressor further comprises a compressor el-ement having a gas inlet and a compressed gas outfet, i^rhereby the pressure vessel has an infet connected to the compressed gas outlet, whereby a minimum pressure valve is provided at an outlet of said pressure vessel, said minimum pressure vafve having a valve inlet connected to the outlet of the pressure vessef and a valve outlet adapted to be connected to a user' s network, whereby said minimum pressure va.Ive comprises a housing whereby the val-ve inlet and the valve outlet are connected by means of a chamber, a valve body movable in said chamber between a closed position in which said valve inlet is cl-osed off, and an open position in which said valve inlet is open, whereby for setting the value of the pressure at which the valve body moves into an open position, use is made of a regu.l-ation unit.

Preferably, the regulating unit uses the pressure at the outlet of the pressure vessel for setting the val,ue of the pressure at whj"ch the valve body moves into an open posit.ion. However, it .is also possible that the regulatlng unit uses the pressure at the inl-et of the pressure vesse.I to set the value of the pressure at which the valvë body moves into an open posltlon. This will be better for the rel iabi l ity. Preferably, a minimum pressure vafve according to the invention ls used.

In the context of the present invention it shoul-d be understood that the benefits presented above with respect to the minimum pressure valve are also val-id for the compressor and the method.

With the intention of better showing the characteristics of the invention, some preferred configurations according to the present invention are described hereinafter by way of an example, without any 1j-miting nature, with reference to the accompanying drawings, wherein:

figure 1 schematically illustrates a compressor 1 a ccordinq to the present invention;

figure 2 schematically illustrates an exploded viei^, of a cut-through of a minimum pressure valve 10 according to an embodiment of the present inventioni figure 3 schematically illustrates a cut-through of a minimum pressure val-ve 10 according to an èmbodiment of the present invention; and figure 4 schematically ilLustrates a cut-through of a minimum pressure valve 10 according to another embodiment of the present inventioni

figures 5 and 6 schematically illustrate a seal 28 which can be used with the minimum pressure valve l-0 according to the invention.

Eigure 1 illustrates a compressor 1 comprising a compressor element 2 having a gas inlet 3 and a compressed gas outl-et 4. Typically the compressor 1is driven by a fixed speed or a variable speed motor 5.

In the context of the present invention, the compressor 1 should be understood as the complete compressor installation, including the compressor element 2, all the tlpicaf connection plpes and valves, the housing oÍ the compressor 1 and possibly the motor 5 driving the compressor element 2.

In the context of the presënt invention, the compressor element 2 should be understood as the compressor element casing i-n which the compression process takes place by means of a rotor or through a reciprocating movement.

Eurther, said compressor element 2 can be selected from a group comprising: a screw, a tooth, a claw, a scroll, a rotary vane, a centrifugal, a piston, etc.

Returning now to figure 1 the compressor 1 further comprises a pressure vessel 6 having an inlet 7 connected to the compressed gas outlet 4 , and an out.l-et 8 connected Èo a user's network 9. Further, a minimum pressure valve 1"0 is provided at the outlet 8, on the fluid conduit provi.ded between the pressure vesse.I 6 and the user's network 9,

Said minimum pressure valve 10 having a va1ve inlet 11 connected to the outlet 8 of the pressure vessel 6 and a valve outlet 12 adapted to be connected to a user's network 9. The minimum pressure val-ve 10 compri s ing a housing 13 with a housing inlet l-4, a housing outlet 15 and a chamber 16, as iLlustrated in figure 2.

Said housing infet 14 being brought in fluid communication with the valve infet 11, and said housing outl-et 15 being brought in fluid communication with the valve outlet 12 when said minimum pressure valve is mounted withj-n the compressor 1. The minimum pressure valve l0 further conprising a valve body l1 movabl-e in said chamber L6 between a cfosed position in which said valve inlet 11 is closed off, and an open position in which said valve inlet 11 is open.

It goes without saying that when the valve inlet 1l is cfosed off, no fluid or practicalJ-y no fluid is allowed to flow through the minimum pressure valve 10, therefore from the housing inlet 14 towards the housing outlet 15 and further towards the user's network 9. whereas, when the valve j.nlet 1,1 is open, fluid is allowed to flow through the minimum pressure val-ve 10, from the housing inlet 14 towards the housing outlet 15 and further reaching the user' s network 9. Eor setting the value of the pressure at which the valve body 17 moves into an open position, the minimum pressure valve 10 according to the present j-nvention further comprises a regulation unit 18. This regulating unit 18 is preferably a separaLe component of the minimum pressure valve 10.

In a preferred embodiment according to the present invention but not l-imiting thereto, the compressor 1 is a Iiquid injected compressor, case in which the pressure vessel 6 preferably comprises a liquid separation vessel (not shown) , or such liquid separation vessel can be mounted as a separate component part of the compressor l. The Iiquid injected within said compressor 1 belng any type of Iiquid such as for example and not fimiting thereto: water, oil, wi-th or without an additive provided the re in .

In a preferred embodinent according to the present invention and not limiting thereto, the compressor 1 is oil inj ected.

It shoufd be however not excluded that the mini-mum pressure valve 10 can be afso mounted within an oil free compressor.

In another embodiment according to the present inventj-on, the regulation unit 18 comprises a conduit 19 connectj-ng a space 20 delimited between the val-ve body L7 and the chamber 16 with the outlet 8 of the pressure vessel 6. The space 20 should be understood AS the gap between the internaf wa11 of the chamber 16 and the val-ve body 17, $rhen the minimum pressure valve 10 in a mounted state. The space 20 wiII be used to be abfe to transport air to a first end 17a of the val-ve body 17.

It goes wj-thout saying that the chamber L6 defines a hol-Iow space wherein the valve body 17 is recej-ved and comprises an internal- wal1 and an external wa11, said externa.L wall being subjected to the pressure val-ue of the fluid at the level of the housing outlet 15. By connecting the space 20 with the outlet 8, the pressure val-ue at the level of said space 20 is j-nfluenced by the pressure val-ue at the 1evel of the outlet 8. AccordingJ.y, the force generated by such pressure value and acting onto the valve body L1 is influencing the opening and the closing of the minimum pressure val-ve 10.

Preferabfy, the regulation unit 18 and the geometry of the conduj.t 19 j-nfluence the rapidity with which such pressure is increased or decreased and al-so the pressure value at which the minj-mum pressure vafve 10 opens or closes.

Returning to figure l, the compressor 1 can further comprises an oi1 separation e.Iement 2l provided on the outlet 8, between the pressure vessel I and the mi nimum pressure va.Ive l-0.

In other words, the oil separation e.l-ement 21 is provj-ded downstream of the pressure vessef 6 Such oil separatlon element 21 being of any type, as for example, and not l-imiting thereto: any type of filter, any type of oi1 separation vessef, or other.

In a preferred embodiment accordj-ng to the present invention and not limiting thereto, the conduit 19 connects the space 20 with the outlet 8 of the pressure vessel 8, upstream from the oi1 separation element 21.

It couLd be equally possible for such a conduit 19 to connect the space 20 with the outlet I of the pressure vessel- 6, downstream of the oiI separation element 21, case i.n which the pressure value at the outlet I wj-ll be affected by the pressure drop across the oil separation el-ement 21.

In a preferred embodj-ment according to the present invention, the minimum pressure val-ve 10, when mounted in a vertical position, does not comprise a sprinq.

The minimum pressure valve 10 according to the present embodiment replaces in fact a sprj-ng which is typical-Iy used within known minimum pressure valves, $rith a regulation unit 18, eLimj-nating components which would be difficul-t to mount or change on site.

In typically used minimum pressure valves 10, a spring is used for setting the pressure value at whj-ch the minj-mum pïessure vafve is opened, and depending on the capacity and operating pressure range of the compressor 1, such a spring is chosen. By replacing such spring with a regufation unit 18, such pressure value can be adapted according to the capacity of the compressor 1. Consequent.l-yr the manufacturing and servicing costs drop and the l-ifetime of the minimum pressure valve l-0 Ís also increased. Such regulation unit 18 allowing for a nanual change of the pressure value or for an automatized change.

Returning to the layout of the minimurn pressuïe valve 10, the valve body 17 comprises a first end 17a positloned closest to the housing outlet l-5 and a second end 17b positioned cl-osest to the housing inlet 14, when the minimum pressure val-ve L0 is in a mounted state.

Preferably, but not limitj-ng thereto, the conduit L9 helps in delimiting two areas within the minimum pressure valve 10, such areas having two different or relatively tr^ro different pressure values. More specifically, the difference between the area of the first end 17a of the valve body 17, and the area at the inlet 14 of the valve. Said conduit L9 can be connected at any location along the height H of the val-ve body 17 or at any location within said chamber 16.

In this case, the conduit 19 is connected to the chamber L6 at approximatefy half of the height H, or at a relatively smaI]- distance from the half of said height H. Horrever, this is not necessary for the invention.

Depending on the si ze of said minimum pressure valve 10, the conduit 19 can be mounted at a distance from the half of said height H ranging from a couple of centimeters to possibl-y tens of centimeters.

In another embodiment according to the present inventj-on, the regulation unit 18 comprises a restricting module 22 adapted to be connected on the one hand to the conduit 19 and on the other hand onto a channe], 23 created through the housing and a i"rall of the chamber.

The channel 23 allowing fluid communication between the fluid flowing through the conduit 19 and the space 20 created between the Ínternaf wall of the chamber 16 and the vafve body 17. Consequently the channel 23 is created as a cut through the housing 13 and the wa1l of the chamber 16.

In a preferred embodiment but not limiting thereto, the restricting module 22 comprises an adjustable element capabl-e of regul,ating the volume of fluid flowing through said channel 23.

Said adjustable element being selected from a group comprising: a screw, a baff valve, a butterfly va1ve, a pl-ate valve, disk vaIve, a poppet val-ve, a ring valve, or any other element capable of sel-ectivefy restricting the flow of ffuid through the channel 23. However, this is not necessary for the invention and can be omitted.

The adjustabfe efement having a flow regulation pattern defined by a linear or a non-finear graph, or an ON/OEF type of regulation. The actuation of such adjustabfe element being either manua] or automati zed.

If the actuation is automatized, said adjustable element can be connected through a wired or wireless connection to a control unit (not shown) all-o&ring for an electronic adjustment of the opening degree or of the position of said adjustable element.

Another possibility is for the adjustable e.Iement to be set at one time, or for the minimum pressure valve 10 to have a continuous regul-ation of said adjustabl,e el,ement. In a preferred enbodiment according to the present invention and not 1j-mj-ting thereto, the restrj-cting module 22 comprises a screw for adapting the flow of fluid flowing through said channel 23 (as shown in figure 4). In such a situation a thread is preferably provided within the channef 23, allowing the screw to be screr^red more or less, depending on the volume of fluid deslred to be allowed to f.Iow through said channel 23.

If the screw is mounted relatively loose, a bigger volume of fluid is allowed to flow though said channel 23 and reach the space 20, allowing the pressure value of thè fl-uid wíthi-n said space 20 to faster reach the val-ue of the pressure of the fluid at the l-evel of the outlet 8. whereas j-f the screw is screwed more within the thread, a smaI1er volume of ffuid is aflowed to f.Iow through the channel 23 and to reach the space 20, allowing for the pressure value of the fl-uld within said space 20 to sl-ower reach the vafue of the pressure of the fluid at the level of thè outIèt 8- In a further embodiment according to the present invention, the vafve body L] comprises a piston 24 received therein movable between a cl-osed position in which the housing inlet L4 is closed off and an open position in which said housÍng inlet 14 is open.

In an embodiment according to the present invention but not limiting thereto, for achieving a stable and balanced minimum pressure valve 10, said piston 24 can be retrieved through the middfe of the valve body !1 , or approximately through the middle.

Àccordingly, the force generated by the pressure value at the l-evel- of the chamber 16 by the fluid flowj-ng through the conduit 19 and further through the channel 23 is acting on both the val-ve body 17 and onto the piston 24. Such piston 24 comprising a first piston end 24a posj-tioned cl-osest to the housing inlet 14 and a second piston end 24b, positioned withj.n the valve body 17, closest to the first end L'la, when said piston 24 is mounted within the valve body 17.

In another embodiment according to the present invention, but not limiting thereto, the pj.ston 24 can comprise a piston channel 25, such a channel 25 al-Iowing for a equalj.zation of the pressure such that the piston 24 can glide inside the valve body 17 without any resistance. AccordingLy, the helght of the piston channef 25 can be chosen during design and it can vary bethreen a fraction of the total height HP of the piston 24 and the total- height of the piston 24 HP.

Preferably, if the piston channe.I 25 is created through the entire height HP of the piston 24, piston 24 further comprises a nozzLe (24c) at the leve.I of the first piston end 24a for control-l-ing the amount of fluid circulating therethrough.

In yet another embodiment accordj-ng to the present invention the valve body l'l can comprise a duct 26, preferably positioned through the middLe or relativel-y through the middle of the vale body 17, starting from the first end 17a and projecting through the va.Lve body 17 to$rards the second end 17b. Such a duct 26 being created in the direction of the fJ-ow of ffuid flowing through the minimum pressure val,ve 10 when said minimum pressure valve 10 is in open position. It shoul-d be noted that the f l-ow that passes through the minimum pressure va.l-ve L0 does not pass through the duct 26 of the valve body 17. There will only be a flow through the duct 26 when the valve body 17 moves. The height of the duct 26 can be selectèd according to the requirements of the minimum pressure valve 10 and the response time needed.

Such duct 26 allowing for the force generated within the chamber 16 to act on a bigger surface of the valve body r7.

In another embodiment according to the present invention and not limiting thereto, the duct 26 comprises a transversal ramification 27, created preferably perpendicular or relatlvely perpendicu]-ar onto the duct 26 and reachi,ng the chamber 16. Consequently the space delimited bethreen the space 20 at the level of the channel 23 or relativel-y cl-ose to where the channel 23 reaches the space 20 1s brought in fluid communication with the space del,imited between the internal wafl of the chamber 16 and the body of the vafve 17 at the level of the fiïst end 17a. Thj-s wilf al.Iow for the control,led pressure to reach the surface of the first end 17a.

In a further preferred embodiment according to the present j-nvention, when mounted, said mininum pressure valve 10 does not comprise a spring between the valve body 17 and the piston 24. Consequentl-y, the correctness of mounting the minimum pressure valve 10 according to the present embodiment is assured, and the amount of time needed to assemble or disassembl-e such a minimum pressure val-ve 10 is reduced considerably. Moreover, the manufacturing and servicing costs are even more reduced s.ince such a typical-fy used spring is replaced by a channel 23, a duct 26, and a specific manner in whj-ch the force generated by the pressure at the leve1 of the chamber 161s aflowed to act onto the valve body 17 and onto the piston 24. In fact the omission of the spring means a reductlon in the vol-ume of material used to manufacture the components of such minimum pressure valve 10. The aforementioned specific manner in which the force generated by the pressure at the level- of the chamber 16 is allowed to act onto the valve body 17 and piston 24 is being set up through the geometry characteristics of the channef 23, duct 26 and the tota.I surface of the valve body 17 onto which the force generated by Èhe pressure of the fluid flowing through said channel 23 is acting.

In another enbodiment according to the pïesent invention, the val-ve body l'l comprises a seaf 28 adapted to be mounted on the outer contour of the valve body 17, between the valve body 17 and the internal- wal-I of the chamber 16. The seaf 28 is mounted under the .l-evel where the channeL 23 is created, therefore between the height at which the channel 23 is created and the second end 17b, when the mj-ni-mum pressure valve 10 is in a mounted state, such rninimum pressure valve 10 being in a closed position.

Consequently, such a seal 28 is positioned such that a separation is created between the space 20 whereby the pressure val-ue is influenced by the pressure of the fluid flowing through said channel 23 and the space delimited between the seal 28 and the second end 17b. Depending on the requirements of the minimum pre s sure valve 10, moïè than one seal 28 can be nounted, such as for example 2, 3 or more seals.

Preferably a bidirectional seal is used. This is a seal that will work in both directions. Figures 5 and 6 show a cross-section of such a sea1. Al-ternatively, two singeacting seals can be used, which are pl-aced back-to-back or front-to-front i-n series. Al-though in figures, the seal is placed around the valve body 17; it would a.Iso be possibfe to place it insi.de the housing 13 of the minirnun pressure valve 10, by providing a groove in the chamber 16.

Preferably, but not fimiting thereto, such seals can be characterized by very l-ow friction and very little stick sIip.

In a further ernbodiment according to the present invention, the valve body 17 comprises a gui-ding unit 29 adapted to be mounted on the outer contour of the valve body 17, between the valve body 17 and the internal wa1l of the chamber 16.

Such guiding unit 29 reducing the wear of the valve body 17 and of the internal wall- of the chamber 16, wear that would be cause by the movement of the va.Ive body 17 within the chamber 16 and the friction generated thereon.

Moreover, such guiding units absorbing the transverse forces occurring during the movement of the valve body 1? within the chamber 16.

In a preferred embodj-ment according to the pre s ent inventj-on but not limiting thereto, the seal 28 is received in between two guiding units 29.

Cons e quent l-y, the $rear is avoided on the height H of the valve body 17 and the stability of the valve body 17 while moving r,rithin the chamber 15 is maintained. In another em.lcodiment according to the present invention, the guldi.ng unit 29 can be in the shape of a seaI, a guiding ring or a guiding tape.

Preferably, for ease of mounting, but not limiting thereto, the guiding unit 29 is in the shape of guiding tape.

Such guiding tape can have a composition se]ected from a group comprising: a polymer based composition, PETE (Polytetrafluoroethylene) based composj-tion, metal based composition, efastomer based compositj-on, fiber and resin based composition, thermopl-astic and fiber glass based compositionr àDy corÈination thereof or any other composition. However, the guiding tape can be of any other suitable material.

In a further embodiment according to the present invention, the chamber 16 comprises a groove 30 or rece s s above a first end 17a of said valve body 17.

Such a groove 30 being cïeated in any shape such as for example and not liniting thereto: rectangle, arch of a circle, pyramidal, in the shape of a dome, in the shape of a mushroom or any other shape.

Preferably, but not limiting thereto, the groove 30 can be created in the shape of a rectangle with rounded edges, whereby the walIs of the rectangle are created by the internal wall- of the chamber L6, having an open end towards the va]-ve body 17. Such groove 30 creating a ho]-l-ow space between the internal wa.ll of the chamber 16 and the valve body 17 at the l-eve1 of the first end 17a.

In yet a further embodiment according to the present invention, the valve body 17 further compri-ses a carved section 31 at the leve]- of the channel 23. Such carved section 3l creating an internal- space betr^reen the internal wa11 of the chamber 16 and the valve body 17 al-f owing for the pressure of the fl-uid flowing through the channe]- 23 to have a bigger influence onto the val-ve body 77.

Preferably, but not limitíng thereto, the carved section 31 can be rea.Iized along the circumference of the vaJ-ve body L7 , creating a circular channel . Consequentl-y, no matter where the transversal ramification 27 ís positioned along the circumference, the ffuid flowing through the channel 23 is reaching the groove 30.

In a further embodiment according to the present inventíon but not Iimiting thereto, the carved section 31 has a height HC equal- to the stroke of the valve.

Consequently, irrespective of the posÍtion of the val-ve, the fluid flowing through the channe.I 23 is reaching the space 20.

In yet another embodiment according to the present j-nvention, the guiding unit 29 comprises a first guiding tape mounted on the outer contour of the valve body 1,7, between the carved section 31 and a fi,rst end 17a of said valve body 17.

In a further embodiment, the guiding unit 29 further comprises a second guidj.ng tape mounted on the outer contour of the valve body 17, between the carved section 31 and a second end 17b of said valve body 17. The carved section 31 is used to transport the controlled pressure to the first end 17a of the valve body 17.

In yet another embodiment according to the present invention, the piston 24 comprises a conical section 32 and a step section 33, said step section 33 being adapted to be brought in contact with the housing 13 of the minimum pressure valve 10 and whereby the conical section 32 is provided between the step section 33 and the housing inlet 14.

The piston 24 with the conical section 32 and the step sectj-on 33 are made such that a guidance for the flow j-s created, ensuring l-ittle or no resistance and to havé such a weight such that it will faII down under the gravity when no other external forces are applied. The piston 24 will al-so take care of the sealing between the outlet 12 of the mj.nimum pressure valve 10 and the outlet of the pressure vesse.I 6.

In a further embodiment according to the present invention, the step section 33 comprises a seal 33a between a nain step section 33b and the housing 13, for reducing the wear of the step section 33 and increasing the sealing capabilities when the minimum pressure valve 10 is brought into a closed state. The seal 33a and the main step section 33b are preferably fixed through mounting onto the conical section 32.

In yet another embodiment according to the present invention, as iffustrated in figure 4, the channel 23 is fluidly connecting the space, defimited by the groove 30 or recess, with the valve inlet 11.

It should be however not excluded that, as explained above, the channel 23 can fluidly connect the space delimited by the groove 30 with the outl,et 8 of the pressure vessef 6.

In a further embodiment according to the present invention, the piston 24 comprises a semi-circular step section. said semi-circuLar step section being adapted to be brought in contact with the housing 13, as illustrated in figure 4.

If such a l-ayout of the step section 33 is adopted, the piston 24 woufd not require a conical section 32 anymore, reducing even more the Iayout of the minimum pressure valve and reducing the number of components. PreferabJ,y but not limiting thereto, the semi-circufar step section further comprises a flange at the level of the outer contour, said f]-ange entering in contact hrith the housing 13 when the mlnimum pressure valve 10 is brought into a closed position. For achieving a smooth movement between the piston 24 and the valve body 17, and for protecting the piston 24 and the valve body L7 from the damaging effects of the friction generated thereon, the piston 24 further comprj-ses a second guiding unit 34 adapted to be mounted between the piston 24 and the vafve body 17.

In a further embodiment according to the pre s ent invention, a top space 35 is created between the chambe r 16 and the first end 17a of the valve body 17.

In order to create such a top space 35, either the valve body 17 can comprise Ieg structures 36 positioned onto the first end L7a, as shown in figures 2 and 3, or the chamber 16 can comprise such leg structures 36, as shown in figure i The shape of such Ieg structures 36 being chosen such that they can $rithstand the force of impact between the valve body 17 and the chamber 16, and in such a way that the valve body 17 would not get stuck while moving into a closed pos j-ton. Said top space 35 being created such that the surface onto which the force generated by the pressure of the fluid flowing through the channel 23 is acting onto the val-ve body is maximized, while the minimum pressure valve 10 is in a cl-osed state.

It should be understood that the shape of the valve body 17, the chamber 16 and of the piston 24 carl be any shape. Preferably and not restricting thereto, the shape IS circular.

In a further embodj-ment according to the present invention, the housing 13, the valve body L7 and the piston 24 can be manufactured through any known technique such as casting or additive manufacturing. other techniques are of course possible. Eor reducing even more the manufacturing costs and material needed therefore, the housíng 13, the valve body 17 and the piston 24 can be manufactured through additive manufacturing.

Depending on the design of the minimum pressure valve l-0, said minimum pressure valve 10 can comprise some or even all the technÍcal features presented herein, in any combination $rithout departing from the scope of the invention. By technical- features it is meant at least: all the components of the compressor 1, the conduit 19, the space 20, the restricting modul,e 22, th,e channel- 23, the piston 24, the piston channef 25, the duct 26, the transversa] ramification 27, Lh.e seal 28, the guiding uni.t 29, the groove 30, the carved section 31, the conical section 32, the step section 33, the seal- 33a, the main step section 33b, the second guiding unit 34, the top space 35 and the 1eg structures 36. Not all these features need to be present. Eor examp]e, the space 20 is only needed in one embodiment. The seal 33a j-s not present in the embodiment of figure 4, where mètal-to-metal contact is used for the seal-ing. Eurthermore, the duct 26 and the transversal ramification 2'1 are not necessary.

The operation of the minimum pressure valve 10 is very simple and as fo11ows. The piston 24, the conical section 32, the step section 33, the seaL 33a and the maj-n step section 33b are all connected to one another to form one piece o.r a so called check valve assembfy.

This check valve assembly can move or slide inside a cavity in the valve body 17.

The check valve assembly can move freely down when the valve body l7 is in the open position. This is the positlon shown in figure 3, whereby the valve body 17 is upwards. When the valve body L7 moves down, the check valve assembly wifl be moved down with it. In this closed position of the mj,nimum pressure valve 10, the valve body L7 closes off the valve inl-et 11 by pressing the piston 24 of the check valve assembly agai-nst the val-ve housing 13 at the valve inlet Ll-.

In this cfosed position, there will be no or practically no fluid af]owed to flow through the minimum pressure valve 10. The va]-ve body 17 will remain j-n this closed position as Ionq as the prèssure at the second end 17b of the val-ve body 17, which corresponds to the pressure at the valve inl-et 11 when the valve body 17 is in the c.Losed position, remains below or uptoa certain pressure vaIue. Thi s pressure va l-ue corresponds to the setpoint of the minj-mum pressure valve 10.

Once the pressure at the second end 17b of the valve body 17 is equal to or larger than this certain pressure value, the valve body 17 wiI.I move to the open position, whereby the vaLve body 17 does not close off the vaLve inlet 11 and the piston 24 wíll move to the open position, as long as the pressurè at the valve inlet 11 is larger than the pressure at the valve outlet 12. In this open position of the minimum pressure valve l- 0, there wifl be fl-uid allowed to f l-ow through the minimum pressure valve 10. The aforementioned pressure val-ue, corresponding to the setpoint of the minlmum pressure valve L0, depends on the pïessure to which the first end 17a of the valve body 17 is subjected or on the pressure in the space 20. This pressure can be regulated by the regul-ating unit 18. To this end, the regulating unit 18 compr j-ses the conduit 19, the restrictinq module 22 wíth. an adj ustable element and the channel 23. The conduit 19 will allow to use the pressure at the outfet of the pressure vessel I to vary the pressure in the space 20 by allowing a flow via the conduit 19, the restricting module 22 and the channel 23. In the examples, the flow will flow further via the carved sectj-on 31, the transversal- ramification 27 and the duct 26 towards the groove 30. In this way, the pressure at the first end 17a of the valve body 17 can be influenced by this f l-ow.

The regulating unit 18 can determine if and how the pressure at the first end 17a of the valve body 17 can be influenced. Eor exampfe, the adjustable element or the aforementioned screw in the channel 23 as shown in figure 4, can be controlled by the regulating unit 18. The regulatlng unit 18 will control the pressure at whj-ch the valve body L7 will- move, whereas the channel 23 wilf determine how fast the valve body 17 will move.

In this way, the regulation unit 18 can determine the setpoint at which the minimum pressure valve 10 will open, i.e. at $rhich point the valve body 17 wifl move to the open position. only when the pressure at the val-ve inlet 11 is different than the pressure to which the first end 17a of the valve body 17 is subjected, the valve body 17 wilf move towards the open position. This is dependent of course on the chosen ratio of the diameters of the first end 17a and the valve Ín.Iet 11. Therefore, by increasing the pressure at the first end 17a of the valve body 17, the pressure at the valve inlet 11 needs to be J.arger before the valve 10 will open, such that it can be assured that the pressure in the pressure vessel 6 never drops below a determined minimum value. The present invention is by no means limited to the embodiments described as an example and shown in the drawings, but such a minimum pressure valve 10 can be realized in al-f kinds of variants, without departing from the scope of the j-nvention.