WO2025127936A1

WO2025127936A1 - A machine of positive displacement, centric reciprocating type with a pressure sealing system and method

Info

Publication number: WO2025127936A1
Application number: PCT/NO2024/050272
Authority: WO
Inventors: Fredrik Christopher THRANE
Original assignee: OTECHOS AS
Current assignee: OTECHOS AS
Priority date: 2023-12-13
Filing date: 2024-12-04
Publication date: 2025-06-19
Anticipated expiration: 2026-06-13
Also published as: NO20240047A1; NO348904B1; NO20231344A1

Abstract

A pressure sealing system in a machine of positive displacement, centric reciprocating type, e.g. a compressor, the machine having a non-rotatable housing (202; 302) which surrounds a pair of first and second mutually movable rotary parts (208, 217 and 308, 317) having co- axial axes of rotation, the housing exhibiting an inner, circular curved wall surface (205; 305) and two planar, parallel inner end wall surfaces (206, 207; 306, 307). A pair of drive shafts (101; 102) for the rotary parts ( extend in mutually opposite directions. Fluid inlets (231, 232; 331, 332); (229', 230'; 329', 330') and outlets (229, 230; 329, 330); (231', 232'; 331', 332') selectively communicate with adjustable angular spaces created by mutual rotary movement of the rotary parts. Pressure sealing between the rotary parts and surfaces of the inner walls is created by the rotary parts being filled with sealing liquid which through apertures in the rotary parts contacts at least parts of the inner wall surfaces of the housing.

Description

A MACHINE OF POSITIVE DISPLACEMENT, CENTRIC RECIPROCATING TYPE WITH A PRESSURE SEALING SYSTEM AND METHOD

Background of the invention

The present invention relates to a pressure sealing system and method in a machine of positive displacement, centric reciprocating type, as defined in the preamble of the independent claims.

In the current system and method of providing pressure sealing in a machine of positive displacement, centric reciprocating type, the machine comprises a non-rotatable housing which surrounds a pair of first and second mutually movable rotary parts having co-axial axes of rotation, the housing exhibiting an inner, circular curved surface and two planar, parallel inner end wall surfaces, a pair of drive shafts for the rotary parts extending in mutually opposite directions, and fluid inlets and outlets selectively communicating with adjustable angular spaces created by mutual rotary movement within the housing of the first and second rotary parts.

More specifically, in an embodiment of the machine using the novel pressure sealing, the machine comprises: a non-rotatable housing which surrounds a pair of first and second mutually movable rotary parts having co-axial axes of rotation, the housing exhibiting an inner, circular curved surface and two planar, parallel inner end wall surfaces, a pair of drive shafts having coordinated joint operation and being connected to the rotary parts, respectively, and the drive shaft of the first rotary part extending in an axially opposite direction to the drive shaft of the second rotary part, the first one of the rotary parts having a hub and at least two wings extending radially therefrom in mutually opposite directions, the radially outermost end of the wings having a curved configuration to be controllably movable along the inner circular curved wall surface of the housing, and with two other opposite, parallel wing regions movable relative to the flat inner end wall surfaces of the housing, the second one of the rotary parts having a hub and at least two wings extending radially therefrom in mutually opposite directions, the radially outermost end of the wings having a curved configuration to be controllably movable along the inner circular curved wall surface of the housing, and with two other opposite, parallel wing regions movable relative to the flat inner end wall surfaces of the housing, each of the wings of the second part being located in an adjustable angular space between a pair of the wings of the first pair, and an axial dimension of the hubs of the first and second rotary parts being a half of the axially directed thickness of the wings of the first and second rotary parts, and fluid inlets and outlets to selectively communicate with said adjustable angular spaces caused by mutual rotary movement of the first and second rotary parts.

Prior art

A type of a machine of positive displacement, centric reciprocating type is inter alia known from WO 2014/112,885. Other related prior art is known from US 2010/ 0,270,752; US 2012/ 0,080,006; US 3,112,062; US 4,169,697; GB 2,007,771 and GB 2,610,324

Such machines have made use of a variety of different types of pressure sealing devices, dependent on machine structure, fluid to be treated and practical and technical aspects related to maintenance and repair.

Pressure sealing in positive displacement machine is commonly and presently based on a sliding contact seal of metal, or of a soft material. Alternatively, it is based on very narrow clearance gaps. These gaps might or might not have some liquid present that comes from liquid present in or injected into the compression chambers. WO 2014/112,885 mentioned above makes use of pressure drop grooves or traps as a way of pressure sealing, and the other publications referred to all disclose use of conventional ways of pressure sealing.

Objects of the invention

The invention has as object to provide a simple and more reliable way of pressure sealing, in particular for a machine of positive displacement type where a safe long-term durability is required without necessitating frequent time related maintenance or costly retrieval of the equipment from not readily accessible locations.

The invention is based on replacing the current types of pressure seals by using a body of sealing liquid as a seal in a centric reciprocating, positive displacement machine, providing thereby a pressure sealing across the wings of the rotary parts. The body of sealing liquid is to be contained within a respective rotor wing partly by walls of the moving rotor wing and partly by inner walls of the machine housing. Thus, pressure sealing between the rotary parts and the inner walls of the housing is created by the rotary parts being filled with sealing liquid which through apertures in the rotary parts contacts at least parts of the inner walls of the housing.

In the context of the present specification of the invention and its claims, “liquid” is intended to imply a sealing liquid to be entered into the mutually rotating rotary parts and to be exposed therefrom towards the interior walls of the machine housing. Further, the term “fluid” is intended to imply a fluid, such as gas, gas mixtures, gas and liquid mixture, or moist gas to be processed activity of the machine.

In currently preferred embodiments of the invention it is considered that the machine is useful as a compressor, a vacuum pump, an expander or a fluid powered engine.

In this context, it will be appreciated that compressors and vacuum-pumps are in effect both compressors sucking fluid, compressing it and releasing it at an outlet at higher pressure than at an inlet. A compressor or a vacuum pump must receive driving power, either motorized or manually powered. A vacuum pump is normally optimized for use at low or very low fluid pressure, whereas a compressor may be used for a wide range of fluid pressures.

Further, it will be appreciated that expanders and fluid powered engines have an opposite way of operation as compared with compressors. The inlet to the machine receives pressurized fluids which push on dedicated surfaces of movable part within the machine and thereby may via main drive shaft drive e.g. a generator, tools, propulsion equipment etc, A simple example of expander is a steam engine, and a fluid powered engine could e,g. be a drill powered by pressurized air.

Summary of the invention

According to the present invention, there is provided a pressure sealing system and a pressure sealing method in a machine of positive displacement, centric reciprocating type as stated in the “Background of the invention” and in the preamble of attached independent claims. The novel and characteristic features of the pressure sealing system appears from its independent claim. More specifically the novel features of the system reside in: provision of pressure sealing between the rotary parts and the inner walls of the housing by the rotary parts containing a supplied pressurized sealing liquid, the rotary parts exhibiting apertures thereby enabling the sealing liquid to pass through the apertures to contacts at least parts of surfaces of the inner walls of the housing, and filling an interspace between the rotary parts and the inside walls with the sealing liquid.

According to further inventive features of pressure sealing system, it comprises an interior space of the hubs and wings of the first and second parts being filled with a pressure sealing liquid, adjacent hub faces of the first and second parts each exhibiting sealing liquid surfaces provided from the hub interior to be present in their common hub interspace, a hub face of the first and second parts which faces the flat inner end surface of the housing exhibiting a sealing liquid surface provided from inside the hub to let sealing liquid be present in the interspace between the hub and the flat inner end surface of the housing, and either a) wherein the two opposite parallel regions of the wings exhibit a sealing liquid surface provided from an aperture into the wing interior to provide sealing liquid in an interspace between the wings and an adjacent opposite face of said flat inner end wall surface of the housing, and wherein said curved configurations of the wings are each constituted by a curved end wall having axial ends configured to allow sealing liquid to move from the wing interior to be present in a defined interspace between the curved walls of the wings and an opposite face portion of the circular curved inner surface of the housing, or b) wherein said curved configurations of the wings exhibit a sealing liquid surface provided from an aperture into the wing interior to allow sealing liquid to move from the wing interior to be present in a defined interspace between the curved end configurations of the wings and an adjacent opposite face portion of the curved inner surface of the housing, and wherein the two opposite parallel regions of the wings exhibit a planar wall having radial ends thereof configured to allow sealing liquid to move from the wing interior to be present in a defined interspace between the wings and an adjacent opposite face of said planar inner end surfaces of the housing.

The novel and characteristic features of the pressure sealing method appears from its independent claim. More specifically pressure sealing between the rotary parts and the inner walls of the housing is provided by filling the rotary parts with a sealing liquid which through apertures in the rotary parts contacts at least parts of surfaces of the inner walls of the housing, thereby filling an interspace between the rotary parts and the inside walls with the sealing liquid, and the sealing liquid is delivered into the rotary parts at a pressure being above an obtainable pressure within the adjustable angular spaces.

Further embodiments of the system and the method of the invention will appear from the attached sub-claims, respectively, as well as from the detailed description with reference to the attached drawings showing non-limiting embodiments of the invention.

Brief description of the drawings

Fig. 1 illustrates the inventive machine with its pressure sealing system and with radially located fluid inlets and outlets.

Fig. 2 illustrates in enlarged view the embodiment of Fig. 1 with radially located fluid inlets and outlets.

Fig. 3 illustrates in enlarged view a variant of the embodiment of Fig. 1 with axially oriented fluid inlets and outlets.

Fig. 4 shows a variant of the embodiment shown on Figs. 1 and 2.

Fig. 5 shows a partial cross-section of Fig.2 without the rotary parts of the machine filled with sealing liquid.

Fig. 6 shows a partial cross-section of Fig. 3 without the rotary parts of the machine filled with sealing liquid.

Fig.7 shows a cross-section of Fig.2 through the machine housing containing the rotary parts and with sealing liquid indicated.

Fig.8 shows a cross-section of Fig.3 through the machine housing containing the rotary parts and with sealing liquid indicated. Fig. 9 shows an enlarged view of Fig. 7.

Fig. 10 shows an enlarged view of Fig. 8.

Fig. 11 shows the view of Fig.5 indicating sealing liquid filled rotary parts.

Fig. 12 shows the view of Fig. 11 without machine housing, indicating sealing liquid filled rotary parts and shaft seals.

Fig. 13 shows the view of Fig. 6 without machine housing and shaft seals, but indicating sealing liquid filled the rotary parts.

Fig. 14 shows a partial cross-section through the view of Fig. 5 and with reference to Figs. 7 and 9.

Fig. 15 shows a partial cross-section through the view of Fig. 6 and with reference to Figs. 8 and 10.

Figs. 16 shows a pair of first and second rotary parts with wings and hubs and attached drive shafts for use in a machine with radially located fluid inlets and outlets, the rotary parts not showing sealing liquid therein.

Figs. 17 is the view of Fig. 16 with the rotary parts showing sealing liquid therein.

Fig. 18 shows the rotary parts of Fig. 16 in cooperative engagement.

Fig. 19 shows the rotary parts of Fig. 17 in cooperative engagement.

Figs. 20 shows a pair of first and second rotary parts with wings and hubs and attached drive shafts for use in a machine with axially oriented fluid inlets and outlets, the rotary parts not showing sealing liquid therein.

Fig. 21 shows the rotary parts of Fig. 20 in cooperative engagement. Fig. 22 shows the view of Fig. 21 with the rotary parts filled with sealing liquid.

Fig. 23a- 23k illustrate mutual rotation of the two rotary parts relative to radially located fluid inlets and outlets on the machine housing.

Fig. 24a- 24k illustrate the views of Fig. 23a-23k, but related to axially oriented fluid inlets.

Fig. 25 illustrates in simplified schematic way separation of sealing liquid from processed fluid.

Detailed description

In the description with reference to the drawings, there are two embodiments related to location of machine inlets and outlets, accordingly implying that the rotary parts also exhibits two embodiments. Structural elements of the machine and of the sealing system having common location in the two embodiments are labelled Ixx, whereas structural elements of the machine and of the sealing element related to radially located fluid inlets and outlets are labelled 2xx, and those related to axially oriented inlets and outlets are labelled 3xx, xx indicating consecutive numbers 01, 02, 03... . etc.

The machine of positive displacement, centric reciprocating type is labelled 201 on Figs. 1, 2 and 4, and 301 on Fig. 3. The machine has a non-rotatable housing 202; 302 which surrounds a pair of first and second mutually movable rotary parts 208, 217; 308; 317 having co-axial axes of rotation. The housing exhibits an inner, circular curved surface 205; 305 and two planar, parallel inner wall surfaces 206, 207; 306, 307 serving as first and second end surfaces of the housing.

A pair of drive shafts 101, 102 having coordinated joint operation are connected to the rotary parts 208, 308; 217, 317, respectively, and the drive shaft 101 of the first rotary part 208, 308 extends in an axially opposite direction to the drive shaft 102 of the second rotary part 217, 317. In a currently preferred embodiment of the coordinated joint operation of the pair of drive shafts 101, 102 there are provided power transfer gear assemblies 203, 204 (Fig. 2) and 303, 304 (Fig. 3) linking the drive shafts 101, 102 with a common main drive shaft 105.

More specifically, at the gear assemblies 203, 204 (Fig. 2) and 303, 304 (Fig. 3) there is attached a non-circular gear 103, 104 to each drive shaft 101, 102, the non-circular gear 103 of one shaft 101 having its major axis forming a first angle (suitably 90°, but not necessarily limited thereto) with a major axis of the non-circular gear 104 of the other shaft 102. The non-circular shaft gears 103, 104 each communicate with the rotary main drive shaft 105 located parallel to the drive shafts 101, 102 of the rotary parts 208, 308; 217, 317 via an intermediate non-circular gear 106; 106’ powered by a circular gear 107; 107’ engaging a further circular gear 108; 108’ attached on the main drive shaft 105. If the machine is to operate as a compressor or a vacuum pump, then the unit 109 connected to the main drive shaft 105 is an electric motor 109 to power the driving of the rotary parts 208; 308 and 217; 317. If the machine is to operate as an expander or a fluid engine, then the unit 109 connected to the main drive shaft 105 is an electric generator 109 or symbolizing the drive of tools or propulsion equipment with power derived from pressurized fluid acting on the rotary parts 208; 308 and 217; 317. It will be recognized that the electric motor 109 could be replaced any other device providing driving power onto the main drive shaft 105.

The configuration shown with both non-circular gears and circular gears has the advantages of: enabling rpm (revolutions per minute) to be easily determined by having different radius of the circular gears; enabling required distance between the drive shafts of the rotary parts and the main drive shaft to be obtained, so that the main drive shaft is at a distance from the housing of the machine; and enabling the size of the non-circular gears to be reduced to have their moment of mass inertia to be as small as possible.

As shown on Fig.4, it is conceivable to only use non-circular gears instead of adding the use of circular gears. There are the advantages of a simpler solution and less losses due to gear engagement, but the disadvantage is it might require larger non-circular gears. The machine 201 on Figs. 1 and 2 appears modified in Fig. 4 as regards the coordinated joint operation of the pair of drive shafts 101, 102, as Fig. 4 shows a non-circular gear 103, 104 attached to each drive shaft 101, 102, and these non-circular gears 103; 104 of the shafts 101, 102 each communicate with a respective non-circular gear 106”; 106’” attached on the rotary main drive shaft 105 located parallel to the drive shafts 101, 102 of the rotary parts 208, 217; 308, 317. The main drive shaft 105 is powered or is powering, as described above. It is appreciated that the machine 301 on Fig. 3 may be modified in a similar way. In the present context oval or elliptical gears as non-circular gears are preferred. Further, noncircular gears could also include gears having other geometrical general shapes or other ways of operating. Examples thereof could e.g. be gears of triangular or square configuration or other polygonal configuration. Also gears with eccentric centre could be an option. It will be appreciated that fluid inlets and outlets and locations thereof may require adaptation to the gear configuration chosen.

A first one 208; 308 of the rotary parts has a hub 209; 309 and at least two wings 210, 211; 310, 311 extending radially therefrom in mutually opposite directions, the radially outermost end of the wings 210, 211; 310, 311 having a curved configuration 212; 312 to be controllably movable along and narrowly spaced from the inner curved surface 205; 305 of the housing 202; 302, and with two other opposite, parallel wing regions 213, 214 and 215, 216; 313, 314 and 315, 316 movable relative to the flat inner end surfaces 206, 207; 306, 307 of the housing 202; 302.

A second one 217; 317 of the rotary parts has a hub 228; 328 and at least two wings 219, 220; 319, 320 extending radially therefrom in mutually opposite directions, the radially outermost end of the wings having a curved configuration 221; 321 to be controllably movable along and narrowly spaced from the inner curved surface 205; 305 of the housing 202; 302, and with two other opposite, parallel wing regions 222, 223 and 224, 225; 322, 323 and 324, 325 movable relative to the flat inner end surfaces 206, 207; 306, 307 of the housing 202; 302. Each of the wings 219, 220; 319, 320 of the second rotary part 217; 317 is located in an adjustable angular space 226, 227; 326, 327 between a pair of the wings 210, 211; 310, 311 of the first rotary part 208; 308. An axial dimension of the hubs 209, 309 and 228; 328 of the first and second rotary parts 208, 308 and 217, 317 is a half of the axially directed thickness t of the wings of the first and second rotary parts 208, 308 and 217, 317.

Fluid inlets 231, 232; 331, 332 and fluid outlets 229, 230; 329, 330selectively communicate with said adjustable angular spaces 226, 227; 326, 327 caused by mutual rotary movement of the first and second rotary parts. It should be noted that these indicated reference numerals on Figs. 23 and 24 for fluid inlets and outlets are valid if the machine 201; 301 operates as a compressor or vacuum pump, However, if the machine 201; 301 operates as an expander or fluid powered engine, then the fluid inlets are 229’, 230’; 329’, 330’ and the fluid outlets are 231’, 232’; 331’, 332’, as indicated on Figs. 23 and 24.

The inventive pressure sealing system now to be described is operative between the rotary parts 208, 308 and 217, 317 and the inner walls 205, 206, 207; 305, 306, 307 of the housing 202; 302.

It is noted from the attached drawing that the hubs 209, 309 and 228; 328 of the first and second rotary parts 208, 308 and 217, 317 are to a substantial extent hollow, and the wings 210, 211; 310, 311 and 219, 220; 319, 320 with one or even two wall faces not present. The reason is that an interior space of the hubs 209, 309 and 228; 328 and wings 210, 211; 310, 311 and 219, 220; 319, 320 of the first and second parts 208, 308 and 217, 317 are filled with a pressure sealing liquid denoted by 233; 333 as shown by coarse hatching on Figs. 6 and 7 and fine hatching on Figs. 8 and 9.

Adjacent hub faces 234, 235; 334, 335 of the first and second parts 208, 308 and 217, 317 each exhibit liquid surfaces provided from the hub interior to be present in their common hub interspace denoted by reference numeral 236, 336 as clearly seen when studying Figs. 8 and 9.

A hub face 237, 238; 337, 338 of the first and second parts 208, 308 and 217, 317 facing the flat inner wall surface 206, 207; 306, 307 of the housing 202; 302 exhibit a liquid surface provided from inside the hub 209, 309 and 228; 328 to let liquid be present in the interspace between the hub and the flat inner end surface of the housing.

As indicated above, if the fluid inlets and outlets are radially located on the housing 202, as shown on Fig. 2, it will yield that the two opposite parallel regions 213, 214 and 215, 216 of the wings 211, 210 exhibit a sealing liquid 233 surface provided from an aperture 242 into the wing interior to provide sealing liquid 233 in an interspace between the wings 210, 211 and an adjacent opposite face of said flat inner wall surface 206, 207 of the housing 202. Further, said curved configurations 212 of the wings are each constituted by a curved end wall 239, 240 having axial ends 241 configured to allow sealing liquid 233 to move from the wing interior to be present in a defined interspace between the curved walls 239, 240 of the wings and an opposite face portion of the circular curved inner wall surface 205 of the housing 202.

Also, as indicated above, fluid inlets and outlets may be axially oriented, as seen on Fig. 3. In this case said curved configurations 312 of the wings exhibit a liquid surface 333 provided from an aperture 339 thereat into the wing interior to allow sealing liquid 333 to move from the wing interior to be present in a defined interspace between the curved end configurations 312 of the wings and an adjacent opposite face portion of the circular curved inner wall surface 305 of the housing 302. The two opposite parallel regions 313, 314 and 315, 316 of the wings 311, 310 exhibit a planar wall 353, 354 and 355, 356 having radial ends 340, 341 thereof configured to allow sealing liquid to move from the wing interior to be present in a defined interspace between the wings 311, 310 and an adjacent opposite face of said planar inner wall surfaces 305, 306 of the housing.

The housing 202; 302 has a plurality of sealing liquid inlets 243; 343 communicating at their outlets 244; 344 with dedicated sealing liquid outlet space volumes 245; 345. These space volumes are each axially restricted by a pair of seals, such as e.g. sim-rings. The volumes 245, 345 extend around the circumference of the respective shaft 101, 102 and the sealing liquid therein also functions as a barrier liquid. Each shaft 101, 102 has sealing liquid inlets 246, 247; 346, 347 communicating with the interior of the wings and the interspace 236; 336 between the hubs. Thus, as the shafts 101 and 102 rotate or not, or are in any rotary position, sealing liquid 233; 333 enters into the interior of the rotary parts via sealing liquid inlets 243; 343, the outlets 244; 344, volumes 245; 345 into the shaft 101; 102..

As seen from Fig. 6 - 9 each hub 209, 228; 309, 328 has a recessed portion 248, 249; 348, 349 into which the shaft sealing liquid inlets 246, 247; 346, 347 opens for further deployment inside the rotary parts.

To prevent any leaking of sealing liquid into the interior of sleeves 250; 251 and 350; 351 integral with the housing 202; 302 surrounding the drive shafts 101, 102, sealing devices like e.g. sim-rings 252; 352 or equivalent sealing means, e.g. mechanical seals having barrier fluid, are provided. Suitably, the shafts 101, 102 are made integral with the first one 208; 308 and the second one 217; 317 of the rotary parts, at least at an end region of the shafts adjoining the hubs 209; 309 and 228; 328, i.e. a region 101’, 102’ of the shafts where they are hollow to receive and forward sealing liquid. The rest of the shafts 101, 102 towards their respective free ends where the non-circular gears 103, 104 are located can either be integral with said regions 101’, 102’ or can be firmly attached thereto.

In summary, the principle of the inventive way of LBPS (Liquid Body Pressure Seal) is according to the invention applied to centric reciprocating machines. The rotary wings and the hubs thereof are filled with a sealing liquid, and the body of sealing liquid is providing pressure sealing instead of using traditional sliding seals, narrow sealing gaps or pressure drop traps.

The sealing liquid flows into the wings through dedicated channels, as described with reference to the drawings, then out of the wings, such as e.g. through narrow gaps between the wings and inside walls of the machine housing, and is partly mixed with a fluid (e.g. a gas to be compressed) during fluid compression. The mixture of sealing liquid and compressed fluid then exit the machine successively at outlets a dedicated discharge rate of the machine. Downstream from the outlets, the sealing liquid is separated from the fluid, cooled, and reinjected into the wings, as indicated on Fig. 24 where 110 indicates inflow of fluid to be processed; 111 indicates a gas/ liquid separator, 112 indicates a liquid cooler, 113 indicates a one-way valve or pump, and 114 is gas outlet from the separator 111. The gas/ liquid separator 111 connected to the machine outlets is useful, in particular when fractions of sealing liquid are not acceptable in a gas phase fluid leaving the machine. The configuration of the separator, cooler and pump could be of any commercial type or a customized version, dependent on gas type and LBPS liquid type.

As indicated earlier, if a compressing mode is replaced by an expansion mode, then used drive fluid may be reused following a separation and cooling of sealing liquid from the drive fluid, i.e. fractions of sealing liquid having entered into the drive fluid during machine operation. It will be appreciated that the sealing liquid body 233; 333 is pressurised to a pressure higher than the chamber, thus ensuring that no fluid travels from the chamber, e.g. 253 on Fig.22, into the liquid of the LB PS.

A compression pressure range of the machine is suitably, though not limited to the range 0 - 50 Bar(g), and the LBPS liquid pressure could suitably be 0.5 -2.0 Bar(g) above that value. Further, a suitable, though not limiting, example range of operational temperatures could be selectable from -50°C to 250°C. Similar ranges may apply for an expansion pressure range, although it will be appreciated that for expansion machines or fluid powered machines, such as e.g. steam engines, the upper region of operational temperature may be substantially higher and even in excess of 600°C. However, it will be appreciated that the physical size and the used machine materials, as well as suitably selected sealing liquid will determine any deviations from the indicated ranges.

When the invention is applied on the centric reciprocating machine, e.g. a compressor or an expander, it will be recalled that all rotor wings and their hubs are filled with liquid. Space between the mutually movable rotor wings constitute either compression or expansion chambers. In a preferred, though non-limiting embodiment, there are in effect created four such chambers. The drawing figures show the machine, with two rotors each having two identical wings. Thus, the rotor wings separate the internal compressor or expander volume into four chambers by virtue of the wings each having two mutally inclined chamber facing walls.

Using the body of LBPS liquid provides for efficient fluid pressure sealing across the rotor wings, thereby eliminating conventional sliding seal friction and thus increasing compressor efficiency.

An advantage of the pressure sealing system is that it yields no mechanical contact between the rotor wings, nor between the wing hubs, nor between the rotor wings and the walls of housing. This implies that no lubricating oil is required to lubricate moving parts. Using LBPS liquids other than oil enables an oil free machine without dry running contact seals. This is an advantage as many compressed fluid applications require compressed fluid free of any oil and free of impurities coming from dry running contact sliding seals. As a result, this also effectively eliminates any issue as regards wear of contact seals and of housing walls and inherently increases required maintenance intervals.

Although oil free compression or expansion is possible with dry running contact seals, such pressure seals do not tolerate high temperatures. As a consequence, that issue limits the compression ratio to 3: 1 or lower per compression stage. The present invention using LBPS allows for oil free compression at much higher compression ratios, typically in the range 3.5: 1 - 6: 1. Similar considerations apply for expansion operational mode.

The invention enables LBPS Liquid, suitably cooled, to circulate through the hollow rotor wings to cool the wings in addition to providing pressure sealing, and exiting of the LBPS liquid implies that it also partly enters the chambers and enables cooling of the fluid arriving into the chamber from the chamber inlet duct during the fluid inflow suction phase and during the fluid compression. Due to this cooling feature, this makes the inlet fluid denser and further increases the compressor efficiency. Effectively, the LBPS liquid cooling the gas during the compression phase will counteract an adiabatic heating of the fluid that would otherwise have taken place during compression in absence of cooling. Adiabatic heating is in general a main source of compressor inefficiency. Further, the LBPS liquid cools the fluid after discharge by the virtue of the LBPS liquid also being mixed with the fluid in the compression chamber discharge duct. This cools the fluid further to obtain a low delivery temperature of the compressed fluid. This advantage further eliminates the need to use a fluid aftercooler. The cooling effect of sealing liquid is however not desirable when the machine operates as an expander, implying that non-cooled sealing liquid may be more suitable for that kind of machine operation,

Additionally, the circulating LBPS liquid cools compressor components to avoid that machine component materials heat up and loose strength, which enables higher material utilization and thus in fact lighter components. Reduced component weight and reduced moment of inertia do indeed increase compressor efficiency. Further, the cooling made possible by using the LBPS liquid yields to a great extent avoidance of material dimension variations of the machine due to temperature induced expansion. This in turn allows for a more precise machine with narrow sealing gaps which reduces LBPS liquid flow through gaps, which in turn increases the compressor efficiency. However, if the machine 201; 301 is an expander or a fluid powered engine, then there is compromise aspect prevailing, i.e. the desire to maintain the machine components at an elevated, though controllable even temperature by at least reducing cooling effect on the drive fluid as far as possible upon any mixing with a fraction of sealing liquid.

It is noted from the description and drawings that there are essentially two ways of operation of the machine, either with radially located fluid inlets and outlets, or axially oriented fluid inlets and outlets, as indicated on Figs. 1 and 2, and Fig. 3. It is observed that physical walls on the wings are, apart from walls thereof facing a compression or expansion chamber, essentially only located at locations thereof which will be passing fluid inlets and outlets, to avoid excessive entry of LBPS liquid in to the compression chambers. Laterally of such limited walls there will be located, transversely of direction of wing rotation the narrow apertures to allow escape of LBPS liquid from the wing interior. Thus, for the version of radial inlets and outlets, the extreme curved end of the wing has such limited wall, whereas the two planar sides of the wings facing the planar interior wall faces of the housing only present a “wall” of LBPS liquid body. For the version of axially directed inlets and outlet, the two planar sides of the wings have such limited wall, whereas the curved extreme end of the wings is open to present only an “end wall” of LBPS liquid body. Further, the hubs of the wings, respectively, will substantially be axially open so to avoid that the hubs rub against each other and against machine material. It will thus be appreciated that the wings and their hubs have a minimum of walls, apart from internal stays for overall structural Stability-

Types of LBPS liquid used must be adapted to the type of fluid to be processed . Suitably, though not limited thereto, LBPS liquid could be selectable from e.g. water, glycol or oil-gas condensate etc. The viscosity of the LBPS liquid should be optimized with regard gas return flow versus viscous friction. However, it is vital that the type and consistency of the LBPS liquid is adapted to the downstream process requirements related to purity and tolerances of different LBPS liquids. As a non-limiting example, hydrogen to be used in fuel cells must not contain any trace of oil, implying that oil cannot be used as LBPS liquid in the process of compressing hydrogen.

Claims

1. A system of providing pressure sealing in a machine of positive displacement, centric reciprocating type, the machine comprising

- a non-rotatable housing (202; 302) which surrounds a pair of first and second mutually movable rotary parts (208, 217 and 308, 317) having co-axial axes of rotation, the housing exhibiting an inner, circular curved surface (205; 305) and two planar, parallel inner end wall surfaces (206, 207; 306, 307),

- a pair of drive shafts (101; 102) for the rotary parts (208, 217 and 308, 317) extending in mutually opposite directions, and

- fluid inlets (231, 232; 331, 332); (229’, 230’; 329’, 330’) and outlets (229, 230; 329, 330);

(231’, 232’; 331’, 332’) selectively communicating with adjustable angular spaces created by mutual rotary movement within the housing of the first and second rotary parts (208, 217 and 308, 317), characterized in that the pressure sealing system comprises:

- provision of pressure sealing between the rotary parts (208, 217 and 308, 317) and the inner walls (205; 305 and 206, 207; 306, 307) of the housing (202; 302) by the rotary parts (208;

308 and 217; 317) containing a supplied pressurized sealing liquid (233; 333), the rotary parts exhibiting apertures thereby enabling the sealing liquid to pass through the apertures to contacts at least parts of surfaces of the inner walls (205; 305 and 206, 207; 306, 307) of the housing, and filling an interspace between the rotary parts and the inside walls with the sealing liquid.

2. The pressure sealing system of claim 1, wherein the pair of drive shafts (101; 102) having coordinated joint operation and being connected to the rotary parts (208, 217 and 308, 317), respectively, and the drive shaft (101) of the first rotary part (208, 308) extending in an axially opposite direction relative to the drive shaft (102) of the second rotary part (217, 317), wherein the first one (208, 308) of the rotary parts having a hub (209; 309) and at least two wings (210, 211; 310, 311) extending radially therefrom in mutually opposite directions, the radially outermost end of the wings (210, 211; 310, 311) having a curved configuration (212; 312) to be controllably movable along the inner circular curved wall surface (205; 305) of the housing (202; 302), and with two other opposite, parallel wing regions (213, 214 and 215, 216; 313, 314 and 315, 316) movable relative to the flat inner end wall surfaces (206, 207; 306, 307) of the housing (202; 302), wherein the second one (217; 317) of the rotary parts having a hub (228; 328) and at least two wings (219, 220; 319, 320) extending radially therefrom in mutually opposite directions, the radially outermost end of the wings (210, 211; 310, 311) having a curved configuration (221; 321) to be controllably movable along the inner circular curved wall surface (205; 305) of the housing (202; 302), and with two other opposite, parallel wing regions (222, 223 and 224, 225; 322, 323 and 324, 325) movable relative to the flat inner end wall surfaces (206, 207; 306, 307) of the housing (202; 302), each of the wings (219, 220; 319, 320) of the second rotary part (217; 317) being located in an adjustable angular space (226, 227; 326, 327) between a pair of the wings (210, 211; 310, 311) of the first rotary part (208; 209), and an axial dimension of the hubs (209; 309 and 228; 328) of the first and second rotary parts (208; 308 and 217; 317) being a half of the axially directed thickness (t) of the wings of the first and second rotary parts, and wherein the pressure sealing system further comprises: an interior space of the hubs (209; 309 and 228; 328) and wings (210, 211; 310, 311 and 219, 220; 319, 320) of the first and second parts (208; 308 and 217; 317) being filled with the pressure sealing liquid (233; 333), adjacent hub faces (234, 235; 334, 335) of the first and second parts (208; 308 and 217; 317) each exhibiting liquid surfaces provided from the hub interior to be present in their common hub interspace (236; 336), a hub face (237, 238; 337, 338) of the first and second parts (208; 308 and 217; 317) which faces the flat inner wall surface (206, 207; 306, 307) of the housing exhibiting a sealing liquid surface provided from inside the hub to let liquid be present in the interspace between the hub and the flat inner wall surface of the housing, and either a) the two opposite parallel regions (213, 214 and 215, 216) of the wings (210, 211) exhibiting a liquid surface provided from an aperture (242) into the wing interior to provide sealing liquid (233) in an interspace between the wings (210, 211) and an adjacent opposite face of said flat inner end wall surface (206, 207) of the housing, and said curved configurations (212) of the wings (210, 211) each being constituted by a curved end wall (239, 240) having axial ends (241) configured to allow sealing liquid (233) to move from the wing interior to be present in a defined interspace between the axial ends (241), the circular curved inner wall surface (205), and the flat inner end wall surfaces (206, 207), or b) said curved configurations (312) of the wings exhibiting a sealing liquid surface (333) provided from an aperture (339) into the wing interior to allow sealing liquid (333) to move from the wing interior to be present in a defined interspace between the curved end configurations (312) of the wings (311, 310) and an adjacent opposite face portion of the circular curved inner wall surface (305) of the housing (302), and the two opposite parallel regions (313, 314 and 315, 316) of the wings (311, 310) exhibiting a planar wall (353, 354 and 355, 356) having radial ends (340, 341) thereof configured to allow sealing liquid to move from the wing interior to be present in a defined interspace between the wings (311, 310) and an adjacent opposite face of said planar inner end wall surfaces (306, 307) of the housing (302).

3. The system of claim 1 or 2, wherein the housing (202; 302) has a plurality of sealing liquid inlets (243; 343) communicating at their outlets (244; 344) with dedicated sealing liquid volumes (245; 345), each shaft (101;102) having sealing liquid inlets (246, 247; 346, 347) communicating with the interior of the wings and the interspace (236; 336) between the hubs.

4. The system of claim 2 or 3, wherein each hub (209, 228); 309, 328) has a recessed portion (248, 249; 348, 349) into which the shaft sealing liquid inlets (246, 247; 346, 347) open.

5. The system of any one of claims 2 - 4, wherein in alternative a) the fluid inlets (231, 232); (229’, 230’) and outlets (229, 230; 231’, 232’) are located on a curved wall part of the housing (202).

6. The system of any one of claim 2 - 4, wherein in alternative b) the fluid inlets (331, 332; 329’, 330’) and outlets (329, 330; 331’, 332’) are located on a planar end wall part of the housing (302).

7. The system of any one of claims 2 - 6, wherein the coordinated joint operation of the pair of drive shafts (101, 102) is provided by attaching an non-circular gear (103, 104) to each drive shaft (101, 102), , and wherein the non-circular gears (103; 104) of the shafts (101, 102) each communicate with a rotary main drive shaft (105) located parallel to the drive shafts (101, 102) of the rotary parts (208, 217; 308, 317) via an intermediate non-circular gear (106; 106’) powered by a circular gear (107; 107’) engaging a further circular gear (108;

108’) attached on the main drive shaft (105), the main drive shaft (105) being powered from or delivering power to a power device (109), e.g. a motor or generator.

8. The system of any one of claims 2 - 6, wherein the coordinated joint operation of the pair of drive shafts (101, 102) is provided by attaching a non-circular gear (103, 104) to each drive shaft (101, 102), and wherein the non-circular gears (103; 104) of the shafts (101, 102) each communicate with a respective non-circular gear (106”; 106’”) on the rotary main drive shaft (105) located parallel to the drive shafts (101, 102) of the rotary parts (208, 217; 308, 317), and wherein the main drive shaft (105) being powered from or delivering power to a power device (109), e.g. a motor or generator.

9. The system of any one of claims 2 - 8, wherein the non-circular gears (103; 104; 106; 106’; 106”; 106’”) are oval or elliptical.

10. The system of any one of claims 1 - 9, wherein the machine (201; 301) has a compressor or vacuum pump mode of operation, and wherein the fluid outlet (231, 232; 331, 332) is linked to a gas/ sealing liquid separator (111) configured to separate sealing liquid (233; 333) from compressed gas phase fluid to deliver the gas phase fluid to a first separator output (114), and wherein separated sealing liquid is cooled in a cooler (112) and delivered by a pump (113) back into the first and second rotary parts of the machine (202; 302).

11. The system of claim 10, wherein the sealing liquid pressure is the range of 0.5 -2.0 Bar(g) above the compression pressure values.

12. A method of providing pressure sealing in a machine of positive displacement, centric reciprocating type, the machine comprising

- a non-rotatable housing (202; 302) which surrounds a pair of first and second mutually movable rotary parts (208, 217; 308, 317) having co-axial axes of rotation, the housing exhibiting an inner, circular curved surface (205; 305) and two planar, parallel inner end wall surfaces (206, 207; 306, 307),

- a pair of drive shafts (101; 102) for the rotary parts (208, 217; 308, 317) extending in mutually opposite directions, and - fluid inlets (231, 232; 331, 332); (229’, 230’; 329’, 330’) and outlets (229, 230; 329, 330); (231’, 232’; 331’, 332’) selectively communicating with adjustable angular spaces created by mutual rotary movement within the housing of the first and second rotary parts (208; 308 and 217; 317), wherein pressure sealing between the rotary parts (208, 217; 308, 317) and the inner walls (205; 305 and 206, 207; 306, 307) of the housing (202; 302) is provided by filling the rotary parts (208; 308 and 217; 317) with a sealing liquid (233; 333) which through apertures in the rotary parts contacts at least parts of surfaces of the inner walls (205; 305 and 206, 207; 306, 307) of the housing, thereby filling an interspace between the rotary parts and the inside walls with the sealing liquid, and wherein the sealing liquid (233; 333) is delivered into the rotary parts (208, 217; 308, 317) at a pressure being above an obtainable pressure within the adjustable angular spaces.

13. The method of claim 12, wherein the sealing liquid pressure is the range of 0.5 -2.0 Bar(g) above the pressure values within the adjustable angular spaces.