Rotary electric machine with integral fluid seal

Abstract

A rotary compressor or expander apparatus includes a sealing scheme that is based on the physical configuration of the leakage path and various characteristics thereof to substantially inhibit fluid flow through the leakage path with minimal leakage.

Description

Field of the Invention

[0001] The present invention generally relates to the field of devices that can compress fluids or utilize compressed fluids to generate power. Such devices include compressors, pumps, expanders, or engines. More specifically, the present disclosure relates to such devices that employ a rotary displacement mechanism, such as positive displacement compressors, pumps, expanders, and positive-replacement engines. Background Art

[0002] The following references are listed as being relevant background to the presently disclosed subject matter:

[0003] -US 4,890,990

[0004] -US 9,638,035

[0005] The acknowledgment of the above references herein should not be construed as meaning that these references are in any way relevant to the patentability of the presently disclosed subject matter.

[0006] Background

[0007] Rotary mechanisms are well known in the field of compressing or expanding fluids. These involve a primary rotor having a plurality of protrusions that rotate in an annular space formed between the opposing surfaces of the rotor and the stator (this rotor is also referred to herein as a "convex rotor"). In such a rotary mechanism, these protrusions that closely engage the opposing stator surface of the annular space, together with reciprocating or rotating elements fixed in the stator and mating into and closely engaging the annular space, define a dynamic chamber, the volume of which changes as these protrusions approach or move away from such fixed elements. Devices embodying such a mechanism are disclosed in US 4,890,990 and US 9,638,035.

[0008] One challenge with such rotary mechanisms is to adequately seal the annular space and prevent leakage of compressed fluid through the small spacing between the rotating element and the surroundings of the device (which is sometimes referred to herein as a "fluid leakage path"). This is particularly severe in cases where, in addition to the primary rotor, the element fixed in the stator and mating into and closely engaging the annular space is a rotating element (commonly referred to in the art as a "concave rotor") that rotates in concert with the primary rotor.

[0009] US 4,890,990 teaches a solution to this problem by means of the paraboloidal cross-sectional shape of the annular space. The differences in the radial and axial expansion of different components during heating are balanced and compensated by the angles of the side walls having the same or similar ratios, thus mainly maintaining a uniform clearance of the leakage path formed between the convex rotor and the stator. Nevertheless, the walls of the fluid leakage path between the convex rotor and the stator will still expand differently, and thus it is virtually impossible to completely seal the fluid leakage path, especially at the sharp corners where the radial and axial expansions are different.

[0010] Additionally, as described above, it is particularly difficult to seal the fluid leakage path occurring at the intersection of the convex rotor and the concave rotor, where the fluid leakage path between the convex rotor and the stator is interrupted, thereby creating a fluid leakage path formed between the convex rotor and the concave rotor, which bifurcates into two fluid paths extending in different directions: one formed between the convex rotor and the stator and the other between the concave rotor and the stator. Since the intersection of the rotors is located between similar hyperboloid geometries of each version, yet having different axes and diameters, there are sharp edges between the different leakage paths at the intersection, which may increase leakage. This problem is complicated by the fact that it is virtually impossible to create such sharp edges at this intersection, which means they will be rounded, thus increasing the clearance of the leakage channel at this point and potentially increasing fluid leakage. Summary of the Invention

[0011] The present disclosure relates to a device having a rotating mechanism, wherein two main rotating parts rotate relative to each other about the same main axis of the device, one may be a rotor and the other may be a stator, and together they form a radially and axially restricted annular space (referred to herein as a "restricted annular space") that is restricted both circumferentially and axially. There is at least one protruding element extending into the restricted annular space from one of the parts and closely engaging the wall of the space, and at least one additional rotor (referred to herein as an "auxiliary rotor") rotating about a different axis (referred to herein as an "auxiliary axis") generally parallel to the main axis, the rotor being disposed in one of the two parts and rotating synchronously with the main rotating part. The auxiliary rotor, being an axisymmetric element, has a portion (which may be referred to herein as a "butting portion") butting against the restricted annular space, the portion closely engaging the wall of the space. The term "closely engaging" means an engagement that substantially minimizes or even substantially avoids fluid flow through. The at least one protruding element and the at least one butting portion define at least one annular chamber therebetween, the length of which continuously changes due to rotation, i.e., it contracts when the protruding element rotates towards the butting portion and contracts when the protruding element rotates away from the butting portion.

[0012] To allow rotation, the spacing between the rotating part and other rotating or static parts needs to be minimized, taking into account the expansion and contraction that inevitably occur when the temperature rises or falls respectively during operation. This minimum spacing results in gaps that create paths (such paths are referred to herein as "leakage paths") for the fluid in the annular chamber to leak and be lost, especially when such a chamber contains high-pressure fluid. The leakage paths extend in a generally axial direction along the surface of the rotating element in the device from within the restricted annular space to the periphery of the device.

[0013] The present disclosure provides a sealing solution for such devices.

[0014] The disclosure herein relates to such a device having a unique sealing arrangement.

[0015] The device of the present disclosure can be configured to operate as one or more of a compressor, a pump, or an expander.

[0016] The present disclosure provides a device for the rotary compression or expansion of a fluid having a unique sealing mechanism for substantially sealing a restricted annular space in which the fluid is compressed or expanded.

[0017] Between any two elements that rotate relative to each other and operate in fluid compression or expansion, a fluid leakage path is formed between the mating surfaces of one rotating element and another element of the device, and thus the working fluid (i.e., the fluid that undergoes compression or expansion) may leak through this fluid leakage path, thereby hindering the operating efficiency, as described above. The present disclosure provides a configuration of the fluid leakage path to minimize or sometimes actually avoid the leakage of fluid through the fluid leakage path. The present disclosure also provides a device that implements such a configuration of the fluid leakage path, in which such fluid leakage is prevented or even substantially avoided (i.e., avoided to a large or significant extent).

[0018] Several embodiments described herein are identified by serial numbers in the order in which they are described, such as "Embodiment (1)", "Embodiment (2)", etc. Each of these embodiments can be implemented in various different ways, which can also be referred to by the term "embodiment"; for example, "by an embodiment of Embodiment (1)…"; etc. It should be noted that these embodiments can be used alone or in any combination in a device used in accordance with the teachings of the present disclosure.

[0019] When referring to leakage paths in accordance with different embodiments of the sealing device, the terms "proximal" and "distal" can be used to denote the relative positions of these sections with respect to the restricted annular space and the flow path of the leaking fluid along the path. In other words, the leakage path extends from within the restricted annular space in a generally proximal to distal direction, where the distal section of the leakage path is further removed along the leakage path compared to the proximal section; and the leaking fluid flows along the leakage path in a generally proximal to distal direction. Flow in the proximal to distal direction can be referred to herein as "forward flow", and flow in the opposite direction can be referred to as "reverse flow".

[0020] The devices of the present disclosure include sealing solutions that are based on the physical configuration of the leakage path and its various characteristics to substantially inhibit fluid flow through the leakage path and minimize leakage. The term "active seal" means that once the device is in operation, the seal is active, and the seal is the result of the leaking fluid flowing through the leakage path. Active sealing is embodied in one or more of the following: (i) a first proximal section of the leakage path (Embodiment (1)), which extends on the circumferential sidewall of the restricted annular space defined by the rotor; (ii) providing an interrupted leakage path, where the leakage path branches into paths in different directions (Embodiment (2)), and optional rotating protrusions extending from the main rotor and / or auxiliary rotor are particularly suitable for interrupting the leakage path configuration. Active sealing can also be supplemented by passive sealing elements (such as rotary seals) known per se. This is particularly achieved by the embodiments of Embodiment (2). The embodiments can be combined with each embodiment to provide an additional sealing effect to one or more other embodiments.

[0021] Some additional terms used herein and their meanings include:

[0022] - The term "apex", as used herein in connection with a fluid leakage path, is used to denote the most radially extended region of an arcuate section of the path.

[0023] - The term "seal" or "sealing" means substantially preventing fluid from leaking from the restricted annular space to the exterior of the device, such prevention at least significantly minimizes fluid loss and sometimes completely prevents such losses. In other words, the seal substantially inhibits such leakage, meaning that even if there is some minor leakage, it has no functional impact or a very small functional impact on the operation of the device.

[0024] - The term "fluid" is used herein to denote any compressible working fluid, which can be a gas, a gas mixture, an aerosol carrying a gas, or other particles, etc. As can be readily understood, the disclosure herein is not limited to any particular compressible fluid that can be selected according to specific operating conditions or requirements.

[0025] - The term "rotor - associated leakage path" means a fluid leakage path formed between the outer surface of a rotor and opposing congruent surfaces (primarily those of the stator). Specifically, the terms "auxiliary - rotor - associated leakage path", "second - part - associated leakage path", and "main - rotor - associated leakage path" mean fluid leakage paths formed respectively between the auxiliary rotor, the second part and the main rotor, and between opposing congruent surfaces.

[0026] - As used herein, the term "about" means that the value can be ±1% of the indicated value and sometimes ±2%, ±3%, ±4%, ±5%, ±6%, ±7% and even up to ±10% of the indicated value. It should be noted that any numerical value given in this disclosure (even with the "about" modifier) should be understood to mean a value that is about the value given.

[0027] Other terms used herein will be understood from their context.

[0028] By Embodiment (1) of the present disclosure, the restricted annular space has sidewalls defined by circumferentially - radially extending protrusions, each protrusion having an arcuate surface that, together with the congruent surface of the rotor, defines a first section of the fluid leakage path that extends in a generally axial direction over the arcuate surface to other sections in the fluid leakage path. The centrifugal force acting on the leaking fluid causes droplets, mist, or other particles dispersed in the fluid to accumulate in the apex region of the arcuate surface and form a film in that region. The film has a sealing effect that prevents fluid from leaking through that section once formed, and thus has the effect of at least partially sealing the restricted annular space.

[0029] By Embodiment (2), the main rotor and the auxiliary rotor are configured such that their intersection forms a branch in the fluid - flow path in the forward - flow direction. The branch divides into two distal sections: one oriented in a generally axial direction along the auxiliary - rotor - associated leakage path and the other oriented in a generally radial direction along a generally radially - extending section of the second - part - associated leakage path or the main - rotor - associated leakage path defined below. This can cause: several active sealing effects, which means a back - flow of leakage losses caused by oscillations due to the periodic change of pressure in all angular sections of the restricted annular space; and an increase in the flow time of the fluid such that the time taken for the fluid to flow through the distal section of the leakage path is less than the pressure change within the angular section of the restricted annular space, and thus, the forward - flowing fluid will reverse flow due to the pressure drop in the associated angular section before passing through the entire leakage path.

[0030] This branching also creates two distinct leakage paths that allow additional anti-leakage features to be added to each of the branches. For example, as will be described below, it also permits the formation of a rotor having one or more circumferentially-radially projecting portions, each projecting portion having an arcuate edge, thereby defining a tortuous fluid leakage path having two generally radial sections extending around the edge of the projecting portion. Similar to that in embodiment (1), the centrifugal force acting on the leaking fluid will cause droplets, mist, or other particles dispersed in the fluid to accumulate at the edge region and form a film in that region. The film has a sealing effect that prevents fluid from leaking through it once formed. Additionally, this distinct separation of the leakage paths permits the installation of rotary seals at the ends of such paths.

[0031] Another embodiment, referred to as embodiment (3) of the present disclosure, also recognizes that in order to avoid a significant change in the gap width between the congruent surfaces of the generally radial sections, in view of the differences in the radial and axial thermally-induced expansions of the restricted annular chamber and other parts of the device, the generally radially extending sections should be angled such that within the operating temperature range of the device, the width change will be within a ±25% tolerance. That is, the generally radial sections should be angled relative to the axis such that given the difference in radial and axial expansion, there will be only a minor change in the gap between the congruent surfaces of such sections. To achieve this, these generally radial sections can have an angle of about 80° to 81° with respect to the axis, typically about 81°. Such sections include, for example, the generally radially extending sections extending from the intersection of embodiment (2), or the generally radial sections defined by the circumferentially-radially projecting portions of embodiment (2).

[0032] Accordingly, the present disclosure provides a device that includes a first part and a second part, one or both of which are rotatable relative to each other about a main axis that defines an axial direction (a direction parallel to the axis) and a radial direction (a direction perpendicular to the axis). There is one or more auxiliary rotors assembled in the first part and rotatable about an auxiliary axis parallel to the main axis. The device can include two or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or even more) auxiliary rotors. The auxiliary rotors are assembled in the first part and rotatable about an auxiliary axis parallel to the main axis. The rotation of the rotatable elements is synchronous and jointly used to compress, expand, or pump fluid within a restricted annular space formed between the first part and the second part. Fluid leakage paths are formed between the congruent opposing surfaces formed between each two of the first part, the auxiliary rotors, and the second part. Each fluid leakage path is configured with an active sealing element that impedes the flow of fluid through the path when rotating, and the active sealing element includes one or both of the following (1) and (2):

[0033] (1) The proximal section of the leakage path, the proximal section extending from within the restricted annular space and formed between the arcuate outer peripheral surface of the circumferential side wall of the space defined by the second part and the congruent surface of the first part, and

[0034] (2) Interrupting the leakage path, wherein the proximal section of the fluid leakage path extending from within the restricted annular space branches into two distal sections, the two distal sections including (i) one or more leakage paths associated with the auxiliary rotor, each leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and the congruent surface of the first part, and (ii) a generally radially extending section of the leakage path associated with the second part formed between the member of the second part and the congruent surface of the first part.

[0035] The present disclosure also provides a device that includes a first part and a second part, one or both of which are rotatable relative to each other about a main axis that defines an axial direction and a radial direction. There is one or more auxiliary rotors assembled in the first part and rotatable about an auxiliary axis parallel to the main axis. The rotations are synchronous and are jointly used to compress, expand, or pump a fluid within a restricted annular space formed between the first part and the second part. A fluid leakage path is formed between each pair of congruent opposing surfaces among the first part, the auxiliary rotor, and the second part. The fluid leakage path has a section with a generally radial trajectory (angled at approximately 80° to 81°, typically approximately 81°) relative to the axis.

[0036] Embodiments of the present disclosure will now be described with reference to two sets of embodiments: one set under the heading "General Aspects" and the other set under the heading "Specific Aspects", both of which relate to the device of the present disclosure. The term "aspect" is used only for linguistic convenience and has no other connotative meaning. Embodiments described in connection with the general aspects are also applicable to the specific aspects, with the necessary changes; and vice versa.

[0037] General aspects

[0038] In accordance with an overall aspect of the present disclosure, the device includes a first part and a second part, one or both of which rotate relative to each other about a main axis that defines an axial direction (a direction parallel to the axis) and a radial direction (a direction perpendicular to the axis). The first part may be a stator, and the second part may be a rotor. The device further includes two or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or even more) additional rotors, herein defined as "auxiliary rotors". The auxiliary rotors are assembled in the first part and rotate about an auxiliary axis parallel to the main axis. The rotation of the elements serves to jointly compress, expand, or pump a fluid within a restricted annular space defined between the first part and the second part at a radially engaging sector around the second part. Two or more auxiliary rotors engage with the second part.

[0039] A fluid leakage path is defined between congruent opposing surfaces between each two of the first part, the auxiliary rotors, and the second part. Each fluid leakage path includes one or more segments extending at the apex of a circumferentially radial rotating protrusion.

[0040] According to an embodiment (1) of this overall aspect, the restricted annular space has two circumferential sidewalls with an arcuate outer peripheral surface extending from the second part, and the fluid leakage path has a proximal segment of the leakage path that extends from within the restricted annular space and is formed between the arcuate outer peripheral surface and a congruent surface of the first part.

[0041] According to an embodiment (2) of this overall aspect, the fluid leakage path is configured with an interrupted leakage path, wherein the proximal segment of the fluid leakage path extending from within the restricted annular space branches into two distal segments, the two distal segments including (i) one or more auxiliary rotor-associated leakage paths, each leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and a congruent surface of the first part, and (ii) a generally radially extending segment of a second part-associated leakage path formed between a member of the second part and a congruent surface of the first part.

[0042] According to an embodiment (3) of this overall aspect, the fluid leakage path includes one or more segments extending in a generally radial direction and has a trajectory such that a thermally induced difference in radial and axial expansion will result in a minimal change in the width of the gap between the congruent surfaces of the segments. The trajectory may be angled at approximately 80° to 81° relative to the axis, typically about 81°.

[0043] The generally arcuate surface may have a semi-circular cross-section, a cross-section defining a portion of an ellipse, a polygonal cross-sectional shape, or generally any type of spline curve. Rotation results in a centrifugal force that causes droplets or mist particles to accumulate at the apex of the arcuate surface where they may coalesce and form a film that inhibits the flow of leaking fluid.

[0044] According to an embodiment of the present disclosure, the proximal section branches into two distal sections, the two distal sections including (i) an auxiliary rotor associated leakage path (for each of one or more auxiliary rotors) and (ii) a second part associated leakage path. Each of the auxiliary rotor associated leakage paths extends in a generally axial direction and is formed between one of the auxiliary rotors and a congruent surface of the first part. The second part associated leakage path is generally radially directed and extends along the face of the second part from the branch point.

[0045] By an embodiment of the present disclosure, the generally radially directed section is connected at its distal end to a distal section that extends in a generally axial direction from the distal end. Thus, the distal section of the second part associated leakage path extending from the branch point has one branch with a generally radial orientation and another branch with a generally axial orientation.

[0046] By an embodiment of the present disclosure, the annular member has a generally radially oriented inner face of a sidewall defining a restricted annular space, an outer face that is longer than the inner face, the outer face extending in a generally radial direction and defining the radially directed section. When the second part is an internal element contained within the scope of the first part or a frame formed or defined by the first part, the outer face extends radially in a generally direction of the axis. When the arrangement is reversed, i.e., the first part is contained within the scope of the second part, the outer face extends in the opposite direction, i.e., in a direction away from the axis.

[0047] Branching the proximal section into two distal sections can create a backflow of leakage losses by fluid oscillating along each branched path, and can also cause a pressure drop at the leakage path branch point and an accompanying reduction in fluid flow velocity and condensation, and thus effectively seal these paths.

[0048] The rotating elements and fluid leakage paths on both sides of the device generally exhibit mirror symmetry about a plane of symmetry that passes through the midline of the restricted annular space and is perpendicular to the main axis.

[0049] The device according to an embodiment of the present disclosure includes at least one circumferentially-radially projecting portion, i.e., a projecting member that extends radially in all directions and has a generally disk-like form, the circumferentially-radially projecting portion extending from a rotating element (e.g., a main rotor and / or an auxiliary rotor) into a congruent receiving recess of another element and being rotatable within the congruent receiving recess, thereby defining a tortuous fluid leakage path, wherein sections of the tortuous fluid leakage path extend in a generally radial direction and are connected to each other by sections extending along the edge of at least one circumferentially-radially projecting portion. Since the leakage path is generally mirror-symmetric on both sides of a restricted annular space, the radially projecting portions can be formed symmetrically on both sides of the space. Two or more such circumferentially projecting portions can be present in each fluid leakage path, and in such a case, they can all have the same radial width (i.e., the maximum diameter of the radially projecting portion) from the rotating element, but typically (but not exclusively) at least one of them has a radial span different from that of at least one other circumferentially projecting portion. In some cases, there may be one circumferentially projecting portion with a relatively large radial span, flanked on both sides by two, three, or more circumferentially projecting portions with relatively small radial spans; or there may be two or three, where the first of these (i.e., the first one encountered by the fluid flowing out of the restricted space through the leakage path) is the largest and the successive ones have decreasing radial extensions.

[0050] At least one circumferentially projecting portion can be formed in the second part and be rotatable within the congruent receiving recess of the first part to define a tortuous auxiliary fluid leakage path, wherein sections of the tortuous auxiliary fluid leakage path extend generally radially from two axial sides of the projecting portion and are connected to each other by sections extending along the generally arcuate edge of the circumferentially projecting portion. Similarly, at least one circumferentially projecting portion can be formed in the auxiliary rotor part and be rotatable within the congruent receiving recess of the first part, thereby defining a tortuous auxiliary fluid leakage path, wherein sections of the tortuous auxiliary fluid leakage path extend generally radially from two axial sides of the projecting portion and are connected to each other by sections extending along the generally arcuate edge of the circumferentially projecting portion. The circumferentially projecting portion can have a generally tapered cross-section extending from its base to a rounded end.

[0051] The fluid flowing through the leakage path is induced by the rotating element to form vortices. When the fluid flows around the circumferentially projecting portion, the rotational component of the vortices increases because the absolute rotational speed at the apex is greater than that at the base. This generates centrifugal forces that grow towards the apex, and these centrifugal forces cause components carried by the fluid (including one or more of droplets, mist, or other particles carried by the fluid) to accumulate at the apex of such sections of the circumferentially-radially projecting portion, thereby generally producing a film that reduces or sometimes almost completely prevents leakage.

[0052] According to an embodiment of the present disclosure, the fluid leakage path associated with the auxiliary rotor has a section distal to the branch point, and the section defines a general trajectory away from the auxiliary axis.

[0053] The generally radially directed section typically has a trajectory such that the thermally induced radial and axial expansion differences will result in a minimal change in the width of the gap between the congruent surfaces of the generally radially directed section. For example, within the operating temperature range of the device, the change in width is less than about ±25%. By way of example, the trajectory of the proximal section is about 81°.

[0054] It should be noted that similar considerations for the trajectory of the generally radially directed section can also apply to the generally radially directed section of the fluid leakage path defined around the circumferential radial protrusion.

[0055] The angle between the section of the fluid leakage path associated with the auxiliary rotor and the outer surface can be about 90°.

[0056] According to an embodiment of the present disclosure, the leakage path is configured such that the flow time of the fluid from the annular restricted space has a travel time through the leakage path (particularly but not only due to the branching at the branch point of the leakage path and the resulting slowdown of the fluid flow rate), and this travel time is longer than the time for the pressure change of the angular portion of the restricted annular space caused by the rotation of the protruding element in the space between the following different pressure strokes: when the device is configured as a compressor or operates as a compressor, including the pressure stroke at high pressure to the suction stroke at low pressure; or when the device is an expander or operates as an expander, from the expansion stroke at high pressure to the full expansion or condensation stroke in the annular chamber. There is some inherent time delay between the pressure rise and the pressure of the fluid flowing through the leakage path (or any fluid flow path for that matter). The fluid pressure in any part of the restricted annular space cyclically changes between high pressure and low pressure. If the flow time of the pressurized fluid through the flow path is longer than the time required for the fluid to travel through the fluid flow path before the fluid finally flows through the leakage path, this can serve as a barrier to fluid leakage. That is, the flow direction in the fluid leakage path will cyclically change between the forward direction and the reverse direction.

[0057] The outer peripheral portion of the rotating element including the vertex of the arc section or the edge of the circumferential radial protrusion defines a section of the leakage path with congruent surfaces. As described above, the section causes the accumulation of particles including droplets and mist, thereby forming a film in such a section, and the film hinders or sometimes substantially prevents the free flow of fluid through the leakage path.

[0058] By embodiments of the present disclosure, the fluid leakage path has an enlarged cross-section at a portion thereof opposite to the edge of the circumferentially radially protruding member. Due to the enlarged cross-section, this results in a local pressure drop, thereby reducing the velocity of the fluid flowing therethrough, and thus promoting the deposition of droplets or mist and the formation of a film.

[0059] By embodiments of the present disclosure, one or more of the leakage paths are configured to have one or more sections with a width different from other sections. The increase in width can cause a pressure drop of the fluid flowing in the leakage path and ultimately slow down the traveling speed of the fluid in the fluid leakage path. The leakage path branch point can also be configured to cause a pressure drop and ultimately slow down the traveling speed of the fluid in the radially directed sections of the leakage path associated with the auxiliary rotor and the leakage path associated with the second part. This can be achieved by changing the dimension of the width, which results in a pressure drop and thus slows down the flow rate of the leaking fluid through the leakage path. In some embodiments, the fluid leakage path can be configured to have multiple width dimension changes. This can be achieved by designing some imperfections in certain sections of the liquid flow path.

[0060] The slowing down of the fluid flowing through the fluid leakage path can also be achieved by a three-dimensional surface structure configured to increase the friction of the fluid flowing in such sections. Such a surface structure can be achieved by introducing minute or even microscopic surface defects, such as abrasions, dents or protrusions. For example, (i) a section of the leakage path associated with the auxiliary rotor extending from the branch and (ii) a part of one or both of the proximal sections have such a three-dimensional surface structure.

[0061] In some embodiments, particularly embodiments of embodiment (2), fluid seals are assembled in one or more of the fluid leakage paths. These can include one or more rotary seal elements assembled at the ends of the fluid leakage path. Such rotary seal elements can include encapsulated ball bearings.

[0062] The device of the present disclosure can be configured to operate as a compressor or an expander. In the case where the device is configured as a compressor, it can be configured to achieve an increase in pressure in a first step of at least two rotation steps and further increase the pressure to a higher pressure in a second step. In the case where the device is configured as an expander, it can be configured to achieve a decrease in pressure in a first step of at least two rotation steps and further decrease the pressure to a lower pressure in a second step.

[0063] The first part may be a stator, and the second part may be a main rotor. The main rotor may include protruding elements extending therefrom into a restricted annular space, the protruding elements in their rotation jointly defining with portions of an auxiliary rotor protruding into the space adjacent thereto two or more chambers within the annular space, the two or more chambers expanding as the protruding elements recede in their rotation away from the portions or contracting as the protruding elements advance in their rotation towards the portions, thereby respectively expanding or compressing the fluid contained therein.

[0064] The second rotating member may be configured as a convex main rotor, i.e., having radially protruding portions (referred to herein as "protruding elements") fitting adjacent to a restricted annular space, and the auxiliary rotor is a concave rotor, i.e., configured with one or more recesses for receiving the protruding portions. The concave rotor provided in the first part is on the outer periphery of the convex rotor, wherein the first part is on the outer periphery of the second part. However, this arrangement may also be reversed, where the first part is defined within the scope of the second part.

[0065] Each of the portions of the auxiliary rotor may include one or more recesses configured to receive the protruding elements, and the rotation of the main rotor and the auxiliary rotor is synchronized to permit such reception as the protruding elements rotate past the portions.

[0066] Specific aspects

[0067] Some specific embodiments will now be described. Explanatory notes that have been provided above and are also applicable to some of the embodiments described below will not be repeated.

[0068] The device of this particular aspect includes a main rotor and a stator. The main rotor is rotatable about a main axis, and the main rotor and the stator have corresponding annular rotor faces and annular stator faces that face each other and define a restricted annular space therebetween. Two or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or even more) auxiliary rotors are embedded in shape - matching receiving spaces within the stator and are radially arranged around the main rotor, and each auxiliary rotor engages the main rotor at a radially engaging sector. Each of the rotors is axially rotatable about an auxiliary axis parallel to the main axis and is configured to rotate synchronously with the main rotor. Each of the auxiliary rotors has an engaging portion having an engaging abutment that abuts into the annular restricted space and is configured to roll in a sealing - fit manner on the annular rotor face. A plurality of protruding elements are provided on the annular rotor face and extend from the annular rotor face into the restricted annular space and are rotatable within the restricted annular space together with the main rotor. The protruding elements are configured to engage adjacent to the annular stator face and be received adjacent in engagement grooves formed in the engaging abutment. The protruding elements jointly define, in their rotation with the engaging portion, transient and volumetric - change compartments for fluid intake, compression, expansion, or discharge.

[0069] According to an embodiment (1) of this particular aspect, each of the fluid leakage paths includes a proximal section that extends in a generally axial direction and is formed between a generally arcuate face of one of the annular members and a congruent surface of the stator.

[0070] According to an embodiment (2) of this particular aspect, each of the fluid leakage paths includes a proximal section that extends in a generally axial direction and is formed between a generally arcuate face of one of the annular members and a congruent surface of the stator; and wherein the proximal section branches into two distal sections, the two distal sections including (i) one or more auxiliary - rotor - associated leakage paths, each leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and a congruent surface of a first part, and (ii) a generally radially - extending section of a second - part - associated leakage path formed between a member of the second part and the congruent surface of the first part.

[0071] According to an embodiment (3) of this particular aspect, each of the fluid leakage paths includes a proximal section that extends in a generally axial direction and is formed between a generally arcuate face of one of the annular members and a congruent surface of the stator; the fluid leakage path includes one or more sections that extend in a generally radial direction and has a trajectory such that a thermally - induced radial - to - axial expansion difference will result in a minimal change in the width of the section. This trajectory can be angled at about 80° or 81° relative to the axis, typically about 81°.

[0072] The rotor has two annular members on opposite sides of a restricted annular space, each annular member having an inner face defining a sidewall of the restricted annular space and an outer face that is longer than the inner face, the outer face extending to a generally axially extending base, and the two walls being connected by an arcuate section.

[0073] Fluid leakage paths are formed between congruent opposing faces defined between the main rotor, the auxiliary rotor, and the stator. Each of the fluid leakage paths includes a proximal section that extends in a generally axial direction and is formed between a generally arcuate face of one of the annular members and a congruent surface of the stator. The generally arcuate face may have a semi-circular cross-section, may have a cross-section defining a portion of an ellipse, a polygonal cross-sectional shape, or generally any type of spline curve.

[0074] By embodiments of the present disclosure, the proximal section branches into two distal sections: (1) an auxiliary rotor associated leakage path, each leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and a congruent surface of the stator; and (2) a generally radially directed section of the main rotor associated leakage path.

[0075] By an embodiment, the radially directed section includes a proximal section that is connected at its distal end to a distal section that extends in a generally axial direction from the distal end. Thus, the radially directed section is one branch of a generally L-shaped distal section of the fluid leakage path and the generally axially directed section is the other branch.

[0076] The branching can cause leakage losses to flow back and accumulate to seal the fluid leakage path.

[0077] The rotating elements and the fluid leakage paths on opposite sides of the device generally exhibit mirror symmetry about a plane of symmetry that passes through the midline of the restricted annular space and is perpendicular to the main axis.

[0078] By an embodiment, there is at least one and typically two or more radially circumferential protrusions that extend from the main rotor and / or from the auxiliary rotor into congruent receiving recesses in the stator and are rotatable within the congruent receiving recesses, thereby defining a tortuous leakage path of the radially directed section of the main rotor associated fluid leakage path, the tortuous leakage path having sections defined around at least one circumferentially radial protrusion. In the case where there are two or more such protruding members, at least one member may have a different radial span from at least one other such member. Such protrusions may generally (but not exclusively) have a tapered cross-section that extends from its base to a circular edge. Centrifugal force caused by rotation of the rotor can cause droplets or mist to accumulate in the edge region of such members to form a film that impedes fluid leakage.

[0079] By way of an example, the auxiliary rotor has an annular recess having a curvature complementary to the curvature of the circular apex of the annular member of the main rotor.

[0080] The proximal section (i.e., closest to and extending directly from the branch point) of the radially directed section of the fluid leakage path associated with the main rotor can have an angle relative to the axis such that the thermally induced radial and axial expansion differences will result in a minimal change in the width of the gap between the relatively congruent surfaces of the substantially radially directed section. For example, within the operating temperature range of the device, the change in width is less than about ±25%. By way of an example, the locus of the proximal section is about 81°.

[0081] It should be noted that similar considerations for the locus of the substantially radially directed section can also apply to the substantially radially directed section of the fluid leakage path defined around the circumferential radial protrusion.

[0082] The fluid leakage path associated with the auxiliary rotor can have a section at the branch that defines a general locus away from the auxiliary axis. The angle between the section of the fluid leakage path associated with the auxiliary rotor and the outer surface can be about 90°.

[0083] As briefly mentioned above, the axial centrifugal force caused by increasing the rotational speed at the edge of the radial protrusion (such as at the apex of the annular member of the main rotor (defined in the proximal section)) causes the fluid-carried components (which may be one or more of the droplets, mists, or other particles carried by the fluid) to accumulate at the apex of such sections. These components can accumulate at such apices and form a film at such locations.

[0084] The leakage path can be configured such that the flow time of the fluid from the annular restricted space has a travel time through the leakage path (e.g., due to the branch) that is longer than the time for the pressure change in any angular portion of the restricted annular space due to the rotation of the protruding element in the space.

[0085] The fluid leakage path can have an enlarged cross-section at the part opposite the edge of the circumferential protrusion. Additionally, one or more of the leakage paths can be configured to have one or more sections with a width different from other sections. The change in width can cause a pressure drop in the fluid flowing through the leakage path and ultimately slow down the travel speed of the fluid in the fluid leakage path.

[0086] The proximal section branches into two distal sections and can be configured to cause a pressure drop and a final slowing of the fluid's travel speed in the leakage path associated with the auxiliary rotor and in the proximal section. Additionally, a portion of one of the distal sections (e.g., the portion near the intersection) can have a three-dimensional surface structure configured to increase the friction of the fluid flowing in such a section. This can be in the form of surface irregularities of the above type.

[0087] The device, particularly the device embodying embodiment (2), can also include fluid seals in one or more fluid leakage paths. These seals can include rotary seal elements fitted at the ends of the fluid leakage paths.

[0088] By way of example, the device in this aspect can be configured to operate as a compressor. By another example, it can also be configured to operate as an expander. By another example, the device can be configured to operate as both a compressor and an expander.

[0089] By one example, the main rotor is fitted inside the stator. By another example, the stator is an internal element and is fitted inside a rotor that rotates around the stator. Example

[0090] In the following sections, the examples will be listed in numbered paragraphs, intended to be added to the above description without limiting it in any way. The examples include such examples drafted in an independent format and other examples that depend on such independent examples, and additional elements can be added to the examples they depend on or these examples can be modified. Examples that depend on one or more examples can also constitute elements that add to or modify other examples they do not depend on.

[0091] Overview

[0092] 1. A device, comprising:

[0093] A first part and a second part, one or both of which are capable of rotating relative to each other about a main axis that defines an axial direction and a radial direction, one or more auxiliary rotors are fitted in the first part and are capable of rotating about an auxiliary axis parallel to the main axis, the rotations being synchronous and jointly used to compress, expand, or pump a fluid in a restricted annular space formed between the first part and the second part; and

[0094] A fluid leakage path formed between congruent opposing surfaces formed between each two of the first part, the auxiliary rotor, and the second part; wherein

[0095] The fluid leakage path is configured with an active sealing element that impedes the flow of fluid through the path when rotating, and the active sealing element includes one or more of the following (1) and (2):

[0096] (1) A proximal section of the leakage path that extends from within the restricted annular space and is formed between an arcuate outer peripheral surface of a circumferential side wall of the space defined by the second part and a congruent surface of the first part, and

[0097] (2) An interrupted leakage path, wherein a proximal section of the fluid leakage path extending from within the restricted annular space branches into two distal sections, the two distal sections including (i) one or more leakage paths associated with an auxiliary rotor, each leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and a congruent surface of the first part, and (ii) a generally radially extending section of a leakage path associated with the second part formed between a member of the second part and a congruent surface of the first part.

[0098] 1A. The apparatus according to Embodiment 1, configured to operate as an expander and / or a compressor.

[0099] Example (1)

[0100] 2. An apparatus, comprising:

[0101] A first part and a second part, one or both of which are capable of rotating relative to each other about a main axis that defines an axial direction and a radial direction, one or more auxiliary rotors being assembled in the first part and capable of rotating about an auxiliary axis parallel to the main axis, the rotations together being used to compress, expand, or pump fluid in a restricted annular space formed between the first part and the second part; and including

[0102] A fluid leakage path formed between congruent opposing surfaces between each two of the first part, the one or more auxiliary rotors, and the second part; wherein

[0103] The restricted annular space has two circumferential side walls with arcuate outer peripheral surfaces extending from the second part, and the fluid leakage path has a proximal section of the leakage path that extends from within the restricted annular space and is formed between the arcuate outer peripheral surface and a congruent surface of the first part.

[0104] 3. The apparatus according to Embodiment 2, wherein the proximal section branches into two distal sections, the two distal sections consisting of:

[0105] Leakage paths associated with the auxiliary rotor, each leakage path extending in a generally axial direction and formed between a congruent surface of the auxiliary rotor and the first part;

[0106] The generally radially directed section of the leakage path associated with the second part.

[0107] 4. The apparatus according to embodiment 3, wherein the radially directed section is connected at its distal end to the distal section of the leakage path associated with the second part extending from the distal end in a generally axial direction.

[0108] 4A. The apparatus according to embodiment 4, wherein the distal sections of the leakage paths associated with the auxiliary rotor and the second part are radially separated relative to the main axis.

[0109] 5. The apparatus according to any one of embodiments 2 to 4A, wherein the annular member has a generally radially oriented inner surface defining the sidewall of the restricted annular space, and an outer surface extending in a generally radial direction that is longer than the inner surface, the outer surface defining the radially directed section.

[0110] 6. The apparatus according to any one of embodiments 3 to 5, including at least one circumferentially radially projecting portion that extends radially from a rotating element into a congruent receiving recess of another element and is rotatable within the congruent receiving recess, thereby defining a tortuous fluid leakage path, wherein sections of the tortuous fluid leakage path extend in a generally radial direction and are connected to each other by sections extending along the edge of the at least one circumferentially radially projecting portion.

[0111] 7. The apparatus according to embodiment 6, including two or more such circumferentially radially projecting portions extending from the rotating element.

[0112] 8. The apparatus according to embodiment 7, wherein the two or more circumferentially radially projecting portions include at least one circumferentially radially projecting portion having a radial span different from that of at least one other circumferentially radially projecting portion.

[0113] 9. The apparatus according to any one of embodiments 6 to 8, including at least one circumferentially radially projecting portion extending from the second part and rotatable within a congruent receiving recess of the first part, thereby defining a fluid leakage path associated with the second part, wherein sections of the fluid leakage path associated with the second part are defined around the circumferential projection.

[0114] 10. The apparatus according to any one of embodiments 6 to 9, comprising at least one circumferentially-radially projecting portion extending from the auxiliary rotor and rotatable within the congruent receiving recesses of the first portion, thereby defining a tortuous auxiliary fluid leakage path, wherein a section of the tortuous auxiliary fluid leakage path is defined around the circumferential projection.

[0115] 11. The apparatus according to any one of embodiments 6 to 10, wherein one or more of the circumferentially-radially projecting portions have a tapered cross-section extending from its base to a circular edge.

[0116] 12. The apparatus according to any one of embodiments 6 to 11, wherein the centrifugal force caused by the rotation of the rotating element causes droplets to accumulate at the edge of the circumferentially-radially projecting portion.

[0117] 13. The apparatus according to any one of embodiments 2 to 12, wherein the auxiliary rotor has an annular recess having a curvature complementary to the curvature of the arcuate outer peripheral surface.

[0118] 14. The apparatus according to any one of embodiments 2 to 13, wherein the generally radially-directed section has a locus such that the thermally-induced radial and axial expansion differences will result in a minimal change in the width of the gap between the relatively congruent surfaces of the section.

[0119] 15. The apparatus according to embodiment 14, wherein the generally radially-directed section is angled relative to the axis by approximately 80° to 81°.

[0120] 16. The apparatus according to any one of embodiments 3 to 15, wherein the auxiliary rotor-associated fluid leakage path has a proximal section extending from the branch, the proximal section defining a generally locus away from the auxiliary axis.

[0121] 17. The apparatus according to embodiment 16, wherein the angle between the section and the second branch is approximately 90°.

[0122] 18. The apparatus according to any one of embodiments 6 to 17, wherein the axial centrifugal force caused by increasing the rotational speed at the edge of the radially projecting portion causes the fluid-carried components and / or fluid condensates to accumulate at the apex of such sections.

[0123] 19. The apparatus according to embodiment 18, wherein the fluid-carried components are droplets, mists or particles that form a film in the section.

[0124] 20. The device according to any one of embodiments 6 to 19, wherein the leakage path is configured such that the flow time of the fluid from the annular restricted space has a travel time through the leakage path that is longer than the time interval between pressure changes in any angular portion of the restricted annular space due to rotation of the protruding element in the space.

[0125] 21. The device according to any one of embodiments 8 to 20, wherein the fluid leakage path has an enlarged cross-section at a portion thereof opposite the edge of the circumferential protruding member.

[0126] 22. The device according to any one of embodiments 2 to 21, wherein one or more of the leakage paths are configured to have one or more sections with a width different from other sections.

[0127] 23. The device according to embodiment 22, wherein the leakage path is configured to have one or more sections with a width wider than other sections.

[0128] 24. The device according to embodiment 23, wherein the change in width is configured to cause a pressure drop in the fluid flowing in the leakage path and the fluid to eventually condense at such sections.

[0129] 25. The device according to any one of embodiments 3 to 24, wherein the branch is configured to cause a pressure drop and the travel speed of the fluid in the distal section to eventually slow down.

[0130] 26. The device according to embodiment 26, wherein a part of one or both of the two distal sections has a three-dimensional surface structure configured to increase the friction of the fluid flowing in such sections.

[0131] 27. The device according to embodiment 26, wherein the surface structure includes surface defects.

[0132] 28. The device according to any one of embodiments 3 to 27, including one or more fluid seals located in corresponding ones of the distal sections of the fluid leakage path.

[0133] 29. The device according to embodiment 28, wherein the seal includes a rotary seal element assembled at the end of the fluid leakage path.

[0134] 30. The device according to embodiment 28, wherein the rotary seal includes a sealed ball bearing.

[0135] 31. The device according to any one of embodiments 2 to 30, configured to operate as a compressor and / or expander.

[0136] 32. The device according to any one of embodiments 2 to 31, wherein the auxiliary rotor is a concave rotor.

[0137] 33. The device according to embodiment 32, wherein the concave rotor is disposed on an outer portion of the two first and second portions.

[0138] 34. The device according to any one of embodiments 2 to 33, wherein the first portion is a stator and the second portion is a main rotor.

[0139] 35. The device according to embodiment 34, wherein the stator includes a frame surrounding the main rotor.

[0140] 36. The device according to embodiment 34 or 35, wherein the main rotor includes a protruding element extending therefrom into the restricted annular space, and the protruding element, in its rotation, jointly defines two or more chambers within the annular space with portions of one or more auxiliary rotors protruding adjacent thereto, and the two or more chambers expand as the protruding element retreats in its rotation away from the portions or contract as the protruding element advances in its rotation toward the portions.

[0141] 37. The device according to embodiment 36, wherein

[0142] each of the portions includes one or more recesses configured to receive the protruding element, and

[0143] the rotation of the main rotor and the auxiliary rotors is synchronized to permit such reception as the protruding element rotates past such portions.

[0144] 38. A device, comprising:

[0145] a main rotor and a stator, the main rotor being rotatable about a main axis, the main rotor and the stator having respective annular rotor faces and annular stator faces facing each other and defining a restricted annular space therebetween;

[0146] two or more auxiliary rotors, the two or more auxiliary rotors being embedded in shape - matching receiving spaces within the stator, radially disposed around the main rotor and each engaging the main rotor at a radially - engaging sector, each auxiliary rotor being axially rotatable about an auxiliary axis parallel to the main axis and configured to rotate synchronously with the main rotor and having a engaging portion with an engaging abutment that abuts into the annular restricted space and is configured to roll in a sealing - fit manner on the annular rotor face; [[ID=3,2]]

[0147] A plurality of protruding elements, said plurality of protruding elements being arranged on said annular rotor surface and extending from said annular rotor surface into said restricted annular space and being capable of rotating together with said main rotor within said restricted annular space, said protruding elements being configured to be adjacent to and received adjacent to said annular stator surface in engagement grooves formed in said engagement abutment portion, said protruding elements jointly defining with said engagement portion in their rotation transient and volumetric change compartments for fluid intake, compression, expansion or discharge;

[0148] A rotor having two annular members on both sides of said restricted annular space, each annular member having an inner surface defining a side wall of said restricted annular space and an outer surface longer than said inner surface, said outer surface extending to a substantially axially extending base, and the two walls being connected by an arcuate section; and

[0149] A fluid leakage path formed between congruent opposing surfaces of each two of said main rotor, said auxiliary rotor and said stator; wherein

[0150] Each of said fluid leakage paths includes a proximal section extending in a substantially axial direction and formed between a substantially arcuate surface of one of said annular members and a congruent surface of said stator.

[0151] 39. The apparatus according to embodiment 38, wherein said proximal section branches into two distal sections, said two distal sections consisting of:

[0152] An auxiliary rotor associated leakage path, each leakage path extending in a substantially axial direction and formed between one of said auxiliary rotors and a congruent surface of said stator; and

[0153] A substantially radially directed section of the main rotor associated leakage path.

[0154] 40. The apparatus according to embodiment 39, wherein said radially directed section is connected at its distal end to a distal section of the main rotor associated leakage path extending from said distal end in a substantially axial direction.

[0155] 40A. The apparatus according to embodiment 40, wherein said distal sections of said auxiliary rotor associated leakage path and said main rotor associated leakage path are radially separated relative to said main axis.

[0156] 41. The apparatus according to embodiment 39 or 40, wherein said branching causes leakage losses to flow back and accumulate for sealing said fluid leakage path.

[0157] 42. The device according to any one of embodiments 39 to 41, comprising at least one main rotor protrusion, which is a circumferentially radial protrusion that extends radially from the main rotor into a congruent receiving recess of the stator and is rotatable within the congruent receiving recess, thereby defining a tortuous distal section of the fluid leakage path associated with the main rotor, the tortuous distal section extending in a generally radial direction and being connected to each other by sections extending along the edges of the at least one circumferentially radial protrusion.

[0158] 43. The device according to any one of embodiments 39 to 42, comprising at least one auxiliary rotor protrusion, which is a circumferentially radial protrusion that extends from the auxiliary rotor and is rotatable within the congruent receiving recess of the stator, thereby defining a tortuous auxiliary fluid leakage path, wherein the sections of the tortuous auxiliary fluid leakage path are defined around the circumferentially radial protrusion.

[0159] 43A. The device according to embodiment 43, comprising at least one of the main rotor protrusions and at least one of the auxiliary rotor protrusions.

[0160] 44. The device according to embodiment 42 or 43, comprising two or more circumferentially radial protrusions that extend from the main rotor into the congruent receiving recess of the stator and are rotatable within the congruent receiving recess.

[0161] 45. The device according to embodiment 44, wherein the two or more circumferentially radial protrusions include at least one circumferentially radial protrusion having a radial span different from that of at least one other circumferentially radial protrusion.

[0162] 46. The device according to any one of embodiments 39 to 45, comprising at least one circumferentially radial protrusion that extends from the auxiliary rotor and is rotatable within the congruent receiving recess of the stator, thereby defining a tortuous auxiliary fluid leakage path, wherein the sections of the tortuous auxiliary fluid leakage path extend in a generally radial direction and are connected to each other by sections extending along the edges of the main circumferentially radial protrusion.

[0163] 47. The device according to embodiment 46, comprising two or more such circumferentially radial protrusions that extend from the auxiliary rotor into the congruent receiving recess of the stator and are rotatable within the congruent receiving recess.

[0164] 48. The device according to embodiment 47, wherein the two or more circumferentially radial protrusions include at least one circumferentially radial protrusion having a radial span different from that of at least one other circumferentially radial protrusion.

[0165] 49. The apparatus according to any one of embodiments 42 to 48, wherein one or more of the circumferentially-radially projecting portions have a tapered cross-section extending from its base to a rounded end.

[0166] 50. The apparatus according to any one of embodiments 42 to 49, wherein the centrifugal force caused by the rotation of the rotor causes droplets to accumulate at the edges of the circumferentially-radially projecting portions.

[0167] 51. The apparatus according to any one of embodiments 42 to 50, wherein the auxiliary rotor has an annular recess having a curvature complementary to the curvature of the arcuate outer peripheral surface of the annular member of the main rotor.

[0168] 52. The apparatus according to any one of embodiments 43 to 52, wherein the radially-directed section has a locus such that a thermally-induced radial and axial expansion difference will result in a minimal change in the width of the gap between the relatively congruent surfaces of the section.

[0169] 53. The apparatus according to embodiment 52, wherein the outer surface of the annular member of the main rotor has a generally locus angled at approximately 80° to 81° relative to the axis.

[0170] 54. The apparatus according to any one of embodiments 43 to 53, wherein the fluid leakage path associated with the auxiliary rotor has a proximal section at the branch, the proximal section defining a generally locus away from the auxiliary axis.

[0171] 55. The apparatus according to embodiment 54, wherein the angle between the section and the outer surface is approximately 90°.

[0172] 56. The apparatus according to any one of embodiments 43 to 55, wherein the axial centrifugal force caused by increasing the rotational speed at the edges of the radially projecting portions causes the fluid-carried components and / or fluid condensates to accumulate in the region of the edges.

[0173] 57. The apparatus according to embodiment 56, wherein the fluid-carried components are droplets, mists or particles that form a film in the section.

[0174] 58. The apparatus according to any one of embodiments 39 to 57, wherein the leakage path is configured such that the flow time of the fluid from the annular restricted space has a travel time through the leakage path that is longer than the time interval between pressure changes in any angular portion of the restricted annular space due to the rotation of the projecting element in the space.

[0175] 59. The device according to any one of embodiments 39 to 58, wherein the fluid leakage path has an enlarged cross-section at a portion thereof opposite the ridge.

[0176] 60. The device according to any one of embodiments 39 to 59, wherein one or more of the leakage paths are configured to have one or more sections with a width different from other sections.

[0177] 61. The device according to embodiment 61, wherein the leakage path is configured to have one or more sections with a width wider than other sections.

[0178] 62. The device according to embodiment 61, wherein the change in width is configured to cause a pressure drop in the fluid flowing in the leakage path and ultimately slow down the traveling speed of the fluid in the fluid leakage path.

[0179] 63. The device according to any one of embodiments 39 to 62, wherein the branch is configured to cause a pressure drop and ultimately slow down the traveling speed of the fluid in the distal section.

[0180] 64. The device according to embodiment 63, wherein a part of one or both of the two distal sections has a three-dimensional surface structure configured to increase the friction of the fluid flowing in such sections.

[0181] 65. The device according to embodiment 64, wherein the surface structure includes one or more of abrasions, dents, and protrusions.

[0182] 66. The device according to any one of embodiments 39 to 65, including one or more fluid seals located in the corresponding one or more of the distal sections of the fluid leakage path.

[0183] 67. The device according to embodiment 66, wherein the seal includes a rotary seal element assembled at the end of the fluid leakage path.

[0184] 68. The device according to any one of embodiments 39 to 67, configured to operate as a compressor and / or an expander.

[0185] 69. The device according to any one of embodiments 39 to 68, wherein the stator includes a frame surrounding the main rotor.

[0186] Example (2)

[0187] 70. A device, comprising:

[0188] a first part and a second part, one or both of which are capable of rotating relative to each other about a main axis that defines an axial direction and a radial direction, one or more auxiliary rotors being mounted in the first part and capable of rotating about an auxiliary axis parallel to the main axis, the rotations being synchronous and together serving to compress, expand or pump a fluid in a restricted annular space formed between the first part and the second part; and

[0189] a fluid leakage path formed between congruent opposing surfaces formed between each two of the first part, the auxiliary rotor(s) and the second part; wherein

[0190] the fluid leakage path is configured with an interrupted leakage path, wherein a proximal section of the fluid leakage path extending from within the restricted annular space branches into two distal sections, the two distal sections including (i) one or more auxiliary rotor-associated leakage paths, each leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and a congruent surface of the first part, and (ii) a generally radially extending section of a second part-associated leakage path formed between a member of the second part and the congruent surface of the first part.

[0191] 71. The apparatus according to embodiment 70, wherein the radially directed section is connected at its distal end to a distal section of the second part-associated leakage path extending from the distal end in a generally axial direction.

[0192] 71A. The apparatus according to embodiment 71, wherein the distal sections of the auxiliary rotor-associated leakage path and the second part-associated leakage path are radially separated from each other relative to the main axis.

[0193] 72. The apparatus according to any one of embodiments 70 to 71A, wherein the annular member has a generally radially oriented inner face defining a side wall of the restricted annular space and an outer face extending in a generally radial direction and longer than the inner face, the outer face defining the radially directed section.

[0194] 73. The apparatus according to any one of embodiments 70 to 72, including at least one circumferentially radially projecting portion that extends radially from a rotating element into a congruent receiving recess of another element and is capable of rotating within the congruent receiving recess, thereby defining a tortuous fluid leakage path, wherein sections of the tortuous fluid leakage path extend in a generally radial direction and are connected to each other by sections extending along an edge of the at least one circumferentially radially projecting portion.

[0195] 74. The device according to embodiment 73 includes two or more of such circumferentially-radially projecting portions extending from the rotating element.

[0196] 75. The device according to embodiment 74, wherein the two or more circumferentially-radially projecting portions include at least one circumferentially-radially projecting portion having a radial span different from at least one other circumferentially-radially projecting portion.

[0197] 76. The device according to any one of embodiments 73 to 75 includes at least one circumferentially-radially projecting portion extending from the second part and rotatable within a congruent receiving recess of the first part, thereby defining a tortuous fluid leakage path associated with the second part, wherein a section of the tortuous fluid leakage path associated with the second part is defined around the circumferentially projecting portion.

[0198] 77. The device according to any one of embodiments 73 to 76 includes at least one circumferentially-radially projecting portion extending from the auxiliary rotor and rotatable within a congruent receiving recess of the first part, thereby defining a tortuous auxiliary fluid leakage path, wherein a section of the tortuous auxiliary fluid leakage path is defined around the circumferentially projecting portion.

[0199] 78. The device according to any one of embodiments 73 to 77, wherein one or more of the circumferentially-radially projecting portions have a tapered cross-section extending from their base to a circular edge.

[0200] 79. The device according to any one of embodiments 73 to 78, wherein the centrifugal force caused by the rotation of the rotating element causes droplets to accumulate at the edge of the circumferentially-radially projecting portion.

[0201] 80. The device according to any one of embodiments 70 to 79, wherein the auxiliary rotor has an annular recess having a curvature complementary to the curvature of the arcuate outer peripheral surface.

[0202] 81. The device according to any one of embodiments 70 to 79, wherein the generally radially-directed section has a trajectory such that a thermally-induced radial-to-axial expansion difference will result in a minimal change in the width of the gap between the opposing congruent surfaces of the section.

[0203] 82. The device according to embodiment 81, wherein the generally radially-directed section is angled relative to the axis at approximately 80° to 81°.

[0204] 83. The device according to any one of embodiments 70 to 82, wherein the auxiliary rotor-associated fluid leakage path has a proximal section extending from the branch, the proximal section defining a general trajectory away from the auxiliary axis.

[0205] 84. The device according to embodiment 83, wherein the angle between the segment and the second branch is about 90°.

[0206] 85. The device according to any one of embodiments 73 to 84, wherein the axial centrifugal force caused by increasing the rotational speed at the edge of the radially protruding portion causes the fluid-carried components and / or fluid condensates to accumulate at the vertices of such segments.

[0207] 86. The device according to embodiment 85, wherein the fluid-carried components are droplets, mists or particles that form a film in the section.

[0208] 87. The device according to any one of embodiments 70 to 86, wherein the leakage path is configured such that the flow time of the fluid flowing into the annular restricted space has a travel time through the leakage path, which is longer than the time interval between the pressure changes in any angular portion of the restricted annular space caused by the rotation of the protruding element in the space.

[0209] 88. The device according to any one of embodiments 70 to 87, wherein the fluid leakage path has an enlarged cross-section at a portion thereof opposite to the vertex of the circumferentially protruding member.

[0210] 89. The device according to any one of embodiments 70 to 88, wherein one or more of the leakage paths are configured to have one or more segments with a width different from other segments.

[0211] 90. The device according to embodiment 89, wherein the leakage path is configured to have one or more segments with a width wider than other segments.

[0212] 91. The device according to embodiment 90, wherein the change in width is configured to cause a pressure drop in the fluid flowing through the leakage path and the fluid to finally condense at such segments.

[0213] 92. The device according to any one of embodiments 70 to 92, wherein the branch is configured to cause a pressure drop and the travel speed of the fluid in the distal segment to finally slow down.

[0214] 93. The device according to embodiment 92, wherein a part of one or both of the two distal segments has a three-dimensional surface structure configured to increase the friction of the fluid flowing through such segments.

[0215] 94. The device according to embodiment 93, wherein the surface structure includes surface defects.

[0216] 95. The apparatus according to any one of embodiments 70 to 94, comprising one or more fluid seals in a respective one or more of the distal sections of the fluid leakage path.

[0217] 96. The apparatus according to embodiment 95, wherein the seal comprises a rotary seal element fitted at an end of the fluid leakage path.

[0218] 97. The apparatus according to embodiment 96, wherein the rotary seal comprises an encapsulated ball bearing.

[0219] 98. The apparatus according to any one of embodiments 70 to 97, configured to operate as a compressor and / or an expander.

[0220] 99. An apparatus, comprising:

[0221] A main rotor and a stator, the main rotor being rotatable about a main axis, the main rotor and the stator having respective annular rotor faces and annular stator faces facing each other and defining a restricted annular space therebetween;

[0222] Two or more auxiliary rotors, the two or more auxiliary rotors being embedded in shape - matching receiving spaces within the stator, radially disposed around the main rotor and each engaging the main rotor at a radially - engaging sector, each auxiliary rotor being axially rotatable about an auxiliary axis parallel to the main axis and configured to rotate synchronously with the main rotor and having an engaging portion, the engaging portion having an engaging abutment that abuts into the annular restricted space and is configured to roll in a sealing - adapted manner on the annular rotor face;

[0223] A plurality of protruding elements, the plurality of protruding elements being provided on the annular rotor face and extending from the annular rotor face into the restricted annular space and being rotatable within the restricted annular space together with the main rotor, the protruding elements being configured to be adjacent to and received in engagement grooves formed in the engaging abutment on the annular stator face, the protruding elements jointly defining, in their rotation with the engaging portion, transient and volumetric - change compartments for fluid intake, compression, expansion, or discharge;

[0224] A rotor having two annular members on opposite sides of the restricted annular space, each annular member having an inner face defining a side wall of the restricted annular space and an outer face longer than the inner face, the outer face extending to a substantially axially - extending base, and the two walls being connected by an arcuate section; and

[0225] A fluid leakage path formed between congruent opposing faces of each two of the main rotor, the auxiliary rotors, and the stator; wherein

[0226] Each of the fluid leakage paths includes a proximal section that extends in a generally axial direction and is formed between a generally arcuate surface of one of the annular members and a congruent surface of the stator; and wherein

[0227] the proximal section branches into two distal sections, the two distal sections including (i) one or more auxiliary rotor-associated leakage paths, each extending in a generally axial direction and formed between one of the auxiliary rotors and a congruent surface of the first portion, and (ii) a generally radially extending section of a second-portion-associated leakage path formed between a member of the second portion and the congruent surface of the first portion.

[0228] 100. The apparatus according to embodiment 99, wherein the radially directed section is connected at its distal end to a distal section of the second-portion-associated leakage path that extends from the distal end in a generally axial direction.

[0229] 100A. The apparatus according to embodiment 100, wherein the distal sections of the auxiliary rotor-associated leakage paths and the second-portion-associated leakage path are radially separated relative to the main axis.

[0230] 101. The apparatus according to any one of embodiments 99 to 100A, wherein the branching causes leakage losses to flow back and accumulate to seal the fluid leakage paths.

[0231] 102. The apparatus according to any one of embodiments 99 to 102, including at least one circumferentially radially projecting portion that extends radially from the main rotor into a congruent receiving recess of the stator and is rotatable within the congruent receiving recess, thereby defining a tortuous distal section of a main-rotor-associated fluid leakage path that extends in a generally radial direction and is connected to each other by sections extending along the edges of the at least one circumferentially radially projecting portion.

[0232] 103. The apparatus according to any one of embodiments 99 to 102, including at least one circumferentially radially projecting portion that extends from the auxiliary rotor and is rotatable within a congruent receiving recess of the stator, thereby defining a tortuous auxiliary fluid leakage path, wherein sections of the tortuous auxiliary fluid leakage path are defined around the circumferentially radially projecting portion.

[0233] 104. The apparatus according to embodiment 102 or 103, including two or more circumferentially radially projecting portions that extend from the main rotor into a congruent receiving recess of the stator and are rotatable within the congruent receiving recess.

[0234] 105. The device according to embodiment 104, wherein the two or more circumferentially-radially projecting portions include at least one circumferentially-radially projecting portion having a radial span different from that of at least one other circumferentially-radially projecting portion.

[0235] 106. The device according to embodiment 105, comprising two or more such circumferentially-radially projecting portions extending from at least one of the rotors into congruent receiving recesses of the stator and being rotatable within the congruent receiving recesses.

[0236] 107. The device according to embodiment 106, wherein the two or more circumferentially-radially projecting portions include at least one circumferentially-radially projecting portion having a radial span different from that of at least one other circumferentially-radially projecting portion.

[0237] 108. The device according to any one of embodiments 102 to 107, wherein one or more of the circumferentially-radially projections have a tapered cross-section extending from its base to a rounded end.

[0238] 109. The device according to any one of embodiments 102 to 108, wherein centrifugal force caused by rotation of the rotor causes droplets to accumulate at the edges of the circumferentially-radially projecting portions.

[0239] 110. The device according to any one of embodiments 102 to 109, wherein the auxiliary rotor has an annular recess having a curvature complementary to the curvature of the arcuate outer peripheral surface of the annular member of the main rotor.

[0240] 111. The device according to any one of embodiments 99 to 110, wherein the radially-directed section has a locus such that a thermally-induced radial-to-axial expansion difference will result in a minimal change in the width of the gap between the opposing congruent surfaces of the section.

[0241] 112. The device according to embodiment 111, wherein the outer surface of the annular member of the main rotor has a generally locus angled at approximately 80° to 81° relative to the axis.

[0242] 113. The device according to any one of embodiments 99 to 112, wherein the fluid leakage path associated with the auxiliary rotor has a proximal section at the branch, the proximal section defining a generally locus away from the auxiliary axis.

[0243] 114. The device according to embodiment 113, wherein the angle between the section and the outer surface is approximately 90°.

[0244] 115. The device according to any one of embodiments 102 to 114, wherein an axial centrifugal force caused by increasing the rotational speed at the edge of the radial protrusion causes accumulation of fluid-carried components and / or fluid condensates in the region of the edge.

[0245] 116. The device according to embodiment 115, wherein the fluid-carried components are droplets, mists or particles that form a film in the section.

[0246] 117. The device according to any one of embodiments 99 to 116, wherein the leakage path is configured such that the flow time of the fluid from the annular restricted space has a travel time through the leakage path that is longer than the time interval between pressure changes in any angular portion of the restricted annular space due to rotation of the protruding element in the space.

[0247] 118. The device according to any one of embodiments 99 to 117, wherein the fluid leakage path has an enlarged cross-section at a portion thereof opposite the ridge.

[0248] 119. The device according to any one of embodiments 99 to 118, wherein one or more of the leakage paths are configured to have one or more sections with a width different from other sections.

[0249] 120. The device according to embodiment 119, wherein the leakage path is configured to have one or more sections with a width wider than other sections.

[0250] 121. The device according to embodiment 120, wherein the change in width is configured to cause a pressure drop in the fluid flowing in the leakage path and ultimately slow down the travel speed of the fluid in the fluid leakage path.

[0251] 122. The device according to any one of embodiments 99 to 121, wherein the branch is configured to cause a pressure drop and ultimately slow down the travel speed of the fluid in the distal section.

[0252] 123. The device according to embodiment 122, wherein a portion of one or both of the two distal sections has a three-dimensional surface structure configured to increase the friction of the fluid flowing in such sections.

[0253] 124. The device according to embodiment 123, wherein the surface structure includes one or more of abrasions, dents and protrusions.

[0254] 125. The device according to any one of embodiments 99 to 124, comprising one or more fluid seals in a respective one or more of the distal sections of the fluid leakage path.

[0255] 126. The device according to embodiment 125, wherein the seal comprises a rotary seal element fitted at the end of the fluid leakage path.

[0256] 127. The device according to any one of embodiments 99 to 126, configured to operate as a compressor and / or an expander.

[0257] 128. The device according to any one of embodiments 99 to 127, wherein the stator comprises a frame surrounding the main rotor.

[0258] Example (3)

[0259] 129. A device comprising:

[0260] a first part and a second part, one or both of which are capable of rotating relative to each other about a main axis that defines an axial direction and a radial direction, one or more auxiliary rotors being fitted in the first part and capable of rotating about an auxiliary axis parallel to the main axis, the rotations being synchronous and together serving to compress, expand or pump a fluid in a restricted annular space formed between the first part and the second part; and

[0261] a fluid leakage path formed between congruent opposing faces formed between each two of the first part, the auxiliary rotor and the second part; wherein

[0262] the fluid leakage path comprises one or more sections extending in a generally radial direction and having a trajectory such that thermally induced radial and axial expansion differences will result in a minimal change in the width of the section.

[0263] 130. The device according to embodiment 129, wherein one or more generally radially directed sections are angled relative to the axis at about 80° to 81°.

[0264] 131. The device according to embodiment 129 or 130, wherein one of the radially directed sections is a distal branch extending from a branch point where a proximal section extending in a substantially axial direction branches into two distal sections, the two distal sections including (i) one or more auxiliary rotor associated leakage paths, each leakage path extending in a substantially axial direction and formed between one of the auxiliary rotors and a congruent surface of the first part, and (ii) the substantially radially extending section formed between a member of the second part and the congruent surface of the first part.

[0265] 132. The device according to any one of embodiments 129 to 131, wherein one of the radially directed sections is a radially directed section defined by at least one circumferentially radially projecting portion that extends radially from a rotating element into a congruent receiving recess of another element and is rotatable within the congruent receiving recess, thereby defining a tortuous fluid leakage path, wherein sections of the tortuous fluid leakage path extend in a substantially radial direction and are connected to each other by sections extending along the edges of the at least one circumferentially radially projecting portion.

[0266] 133. A device comprising:

[0267] A main rotor and a stator, the main rotor being rotatable about a main axis, the main rotor and the stator having respective annular rotor faces and annular stator faces that face each other and define a restricted annular space therebetween;

[0268] Two or more auxiliary rotors that are embedded in shape - matching receiving spaces within the stator, are radially disposed around the main rotor, and each engage the main rotor at a radially engaging sector, each auxiliary rotor being axially rotatable about an auxiliary axis parallel to the main axis and configured to rotate synchronously with the main rotor and having a engaging portion that has an engaging abutment that abuts into the annular restricted space and is configured to roll in a sealingly adapted manner on the annular rotor face;

[0269] A plurality of projecting elements that are disposed on the annular rotor face and extend from the annular rotor face into the restricted annular space and are rotatable within the restricted annular space together with the main rotor, the projecting elements being configured to engage adjacent to the annular stator face and being received adjacent to each other in engaging grooves formed in the engaging abutment, the projecting elements jointly defining, in their rotation with the engaging portion, transient and volumetric change compartments for fluid intake, compression, expansion, or discharge;

[0270] A rotor having two annular members on opposite sides of the restricted annular space, each annular member having an inner face defining a side wall of the restricted annular space and an outer face longer than the inner face, the outer face extending to a substantially axially extending base, and the two walls being connected by an arcuate section; and

[0271] Fluid leakage paths formed between congruent opposing faces of each two of the main rotor, the auxiliary rotor, and the stator; wherein

[0272] Each of the fluid leakage paths includes a proximal section extending in a substantially axial direction and formed between a substantially arcuate face of one of the annular members and a congruent surface of the stator; and wherein

[0273] The fluid leakage path includes one or more sections extending in a substantially radial direction and having a trajectory such that a thermally induced radial-to-axial expansion difference will result in a minimal change in the width of the section.

[0274] 134. The apparatus according to embodiment 133, wherein one or more substantially radially directed sections are angled relative to the axis at approximately 80° to 81°.

[0275] 135. The apparatus according to embodiment 133 or 134, wherein one of the radially directed sections is a distal branch extending from a branch point where a proximal section extending in a substantially axial direction branches into two distal sections, the two distal sections including (i) one or more auxiliary rotor-associated leakage paths, each leakage path extending in a substantially axial direction and formed between one of the auxiliary rotors and a congruent surface of the first part, and (ii) the substantially radially extending section formed between a member of the second part and the congruent surface of the first part.

[0276] 136. The apparatus according to any one of embodiments 133 to 135, wherein one of the radially directed sections is a radially directed section defined by at least one circumferentially radially projecting portion that extends radially from a rotating element into a congruent receiving recess of another element and is rotatable within the congruent receiving recess, thereby defining a tortuous fluid leakage path, wherein the sections of the tortuous fluid leakage path extend in a substantially radial direction and are connected to each other by sections extending along the edge of the at least one circumferentially radially projecting portion. Description of the Drawings

[0277] To better understand the subject matter disclosed herein and to illustrate how the subject matter may be practiced in practice, embodiments will now be described by way of non-limiting example only with reference to the schematic drawings, in which:[[]]END

[0278] Figure 1 is a partial isometric view of a device according to an embodiment of the present disclosure, in which some parts of the stator are cut away to better view the main rotor and the two auxiliary rotors.

[0279] Figure 2 is at Figure 1 a cross-section through the auxiliary rotor of the device in a partial isometric view of the auxiliary rotor.

[0280] Figure 3 is an isometric view radially through the center of the recess of the auxiliary rotor of the device housing Figure 1 thereof.

[0281] Figure 4 Shows the same isometric view after assembling the auxiliary rotor.

[0282] Figure 5 Shows a radial cut through a portion between successive auxiliary rotors Figure 1 of the device.

[0283] Figure 6 is a view similar to Figure 5 of a device according to another embodiment.

[0284] Figure 7 Shows a device according to another embodiment of the present disclosure in isometric and partial axial cross-section.

[0285] Figure 8 Shows an isometric and partial axial cross-section of a device according to another embodiment of the present disclosure.

[0286] Figure 9 Shows an isometric and partial axial cross-section of a device according to another embodiment of the present disclosure.

[0287] Figure 10 is an isometric and partial radial and axial cross-section of a device according to yet another embodiment of the present disclosure.

[0288] Figure 11 is an isometric view of a device according to yet another embodiment of the present disclosure, which shows a gear drive system. DETAILED DESCRIPTION

[0289] In the following description, some illustrative and non-limiting embodiments will be described with reference to the accompanying drawings.

[0290] When describing the different embodiments, reference numerals will be used, where the first digit is an indicator of the successive numbering of the embodiment and the subsequent reference numerals are related to the element numbers. Thus, for example, element 102 is related to the stator of the device of Figures 1 to 5 the first embodiment shown, while element 302 is related to Figure 6Relates to the stator of the second embodiment shown. In other words, elements numbered with the same reference numeral except for the first digit perform the same function. When describing different embodiments, the description may skip elements that have already been described in connection with other embodiments, and the reader is referred to the description of the previously described embodiments to understand the structure and / or function of such elements.

[0291] First, refer to Figures 1 to 5 , in which an apparatus 100 according to an embodiment of the present disclosure is schematically shown in several views. The apparatus 100 includes a stator 102, a main rotor 104, and a plurality of auxiliary rotors 106 (six auxiliary rotors in this exemplary embodiment; however, the number of auxiliary rotors may be any number specified by design and engineering considerations). The rotors are rotatable about a main axis, which is represented by the dashed line 108 in Figure 1 . In this embodiment, the rotors are contained within the stator. In other embodiments, this may be reversed, as shown below in Figure 10 . The stator 102 is schematically shown as an annular ring in the figure. However, as can be understood, the stator may also be embodied as a larger frame having any shape specified by engineering or other considerations. Similarly, the main rotor 104 is schematically shown as a rotating annular element. However, as can also be understood, the rotor may have various other configurations, for example, the hollow space within the rotor may be filled, or the rotor may have an integral structure for connection to a shaft, etc.

[0292] Generally, the apparatus may be configured to operate as a compressor, in which case the main rotor 104 may be connected to an electric motor, for example, an electric motor, or may be configured to operate as an expander, in which case the main rotor 104 may be coupled to an energy generator, for example, a generator.

[0293] The stator 102 and the rotor 104 have corresponding annular stator faces 110 and annular rotor faces 112 that face each other and define a restricted annular space 114 therebetween (best visible in Figure 3 and Figure 5 ).

[0294] A plurality of auxiliary rotors 106 are embedded in shape-matching receiving recesses 116 (visible in Figure 3 ) within the stator 102, and the receiving recesses define a radial engagement sector between the auxiliary rotors and the main rotor. Each of the auxiliary rotors 106 is rotatable about an auxiliary axis parallel to the main axis 108 (by Figure 4The dashed line 118 therein indicates axial rotation and is configured to rotate synchronously with the main rotor 102. The synchronization can be achieved by a gear drive system as shown in FIG. 11. Each of the auxiliary rotors 106 has an engagement portion 120, and the engagement portion 120 has an engagement abutment 122 that abuts into the restricted annular space 114 and is configured to roll on the annular rotor surface 112 in a tight engagement. On both sides of the engagement abutment are two annular recesses 123A, 123B, and the two annular recesses are configured to tightly engage with annular members 124A, 124B that are formed on both sides and define the side walls of the restricted annular space 114.

[0295] A plurality of protruding elements 126 (one of which is visible in Figure 1 are provided on the annular rotor surface 112 and extend from the annular rotor surface into the restricted annular space 114, and can rotate within the restricted annular space together with the main rotor 104. The protruding elements 126 are configured to tightly engage the annular stator surface 110 and are tightly received in engagement grooves 128 formed on the engagement abutment 122 of the auxiliary rotor 106. The protruding elements 126 jointly define, in their rotation, transient and volume-changing compartments for fluid intake, compression, expansion, or discharge, as is known per se. Also as is known per se, the restricted annular space has an inlet port for introducing fluid into the restricted annular space and an outlet port for discharging the liquid from the restricted annular space; and has valve means to allow the fluid to be filled into the restricted annular space in a timely manner through the corresponding inlet and outlet ports and to allow the fluid to be discharged from the restricted annular space in a timely manner.

[0296] Each of the two annular members 124A, 124B has corresponding inner surfaces 128A, 128B that define the side walls of the restricted annular space 114. The outer surfaces 130A, 130B of the corresponding annular members 124A, 124B are longer than the inner surfaces and extend in a generally radial direction to face the bases 132A, 132B. The annular members 124A, 124B have outer peripheral arcuate surfaces 141A, 141B, as generally explained above, and the outer peripheral arcuate surfaces exert a centrifugal force during their rotation, and the centrifugal force causes the film to deposit at its apex, thereby providing a seal to prevent and reduce fluid leakage loss from the restricted annular chamber. The arcuate section is presented as a section having a semi-circular cross-section, but it can also have a cross-section that defines a part of an ellipse, a polygonal cross-sectional shape, or generally the arcuate section can follow any type of spline curve.

[0297] The bases 132A, 132B are the first parts of a generally axially oriented fluid leakage path, and in this exemplary embodiment, the fluid leakage path is a tortuous path having a generally radial section defined by annular radial protrusions 134A, 134B.

[0298] The device 100 of this embodiment has mirror symmetry about a plane passing through the middle of the restricted annular space 114 that is perpendicular to the axis 108 and between the two annular members 124A, 124B. While mirror symmetry of all the functional elements of the device (the functional elements include the rotor, the stator portion engaged with the rotor, and the fluid leakage paths defined therebetween) is typical for designing a device according to the present disclosure, and in fact all the devices illustrated herein have this mirror-symmetric design, this mirror symmetry is not the only way to design a device according to the present disclosure. For example, for various design and engineering considerations, the auxiliary rotor may not have mirror symmetry, and thus the auxiliary-rotor-associated leakage paths on one side may be different from those on the other side. By another example, the stator may have an overall asymmetric design, e.g., in view of engineering considerations for coupling the device to other foreign elements. Additionally, the rotor may be connected to a motor or a generator on one side, which in itself causes asymmetry (but in this case, the auxiliary rotor and the leakage paths can still have a mirror-symmetric design).

[0299] To permit the rotational elements to rotate, there must be spacing between the different elements, and this spacing, even if small, will create fluid leakage paths between the congruent opposing faces formed between the main rotor and each auxiliary rotor, between the main rotor and the stator, and between each of the auxiliary rotors and the stator. Such leakage paths 140A, 140B are in Figure 5is schematically marked by the sinuous arrows, showing the lateral flow direction of the leaking fluid from within the restricted annular space 114 towards the two sides 142A, 142B of the device. This fluid leakage path has proximal sections 141A, 141B that pass through the arcuate sections 136A, 136B. The rotor 104 rotating about the axis 108 generates a centrifugal force that causes droplets and mist to accumulate at the apexes of the arcuate sections 136A, 136B, thereby forming a film that impedes the flow of the leaking fluid through the leakage paths 140A, 140B. The leakage paths 140A, 140B branch into two distal sections relative to the branch points 154A, 154B, which include radially directed sections 143A, 143B that extend along the outer surfaces 130A, 130A and connect to a distal generally axially tortuous section that has a generally radial portion defined by and extending along the edges of the annular radial protrusions 134A, 134B. Similarly, as described above in connection with the proximal sections 141A, 141B, the centrifugal force causes a film to form at the edges of the annular radial protrusions 134A, 134B, thereby impeding the flow of the leaking fluid through the fluid leakage paths 140A, 140B. Thus, for the fluid leakage paths 140A, 140B, several active fluid sealing mechanisms operate together, one defined by the arcuate sections 136A, 136B and another defined by the annular radial protrusions 134A, 134B, and yet another defined by the branching at the branch points 154A, 154B.

[0300] The auxiliary rotor associated leakage paths 144A, 144B extend generally axially and are formed between each of the auxiliary rotors 106 and the congruent surfaces of the stator 102. The auxiliary rotor associated leakage paths 144A, 144B extend along a tortuous path over the circumferential radial protrusions 146A, 146B.

[0301] The main rotor associated leakage path consists of proximal sections 141A, 141B, radially directed sections 150A, 150B, and distal sections 152A, 152B. The proximal sections 141A, 141B extend generally axially from the restricted annular space 114 (not visible in the given cross-section Figure 2 to the branch points 154A, 154B and are formed between the arcuate sections 136A, 136B and the congruent surfaces of the stator. The radially directed sections 150A, 150B extend generally radially from the intersections 154A, 154B and are defined by the outer surfaces and the congruent surfaces of the stator. The distal sections 152A, 152B extend along a tortuous path in a generally axial direction over the circumferential radial protrusions 134A, 134B between the faces of the main rotor and the congruent surfaces of the stator.

[0302] It should be noted that the mating surfaces defining the proximal sections 140A, 140B of the main rotor associated leakage paths (as visible in Figure 2 ) are the mating surfaces of the recesses 123A, 123B, but this is only at the radial cross - sectional positions where the recesses 123A, 123B contact the annular sections 136A, 136B. At other radial positions, the mating opposing surfaces are those of the stator. It should also be noted that in this cross - section, the engagement abutment 122 engages tightly with the annular rotor surface 112, while at other positions of the engagement abutment 122, there is a spacing between the engagement abutment 122 and the annular rotor surface 112, as can be seen, for example, in Figure 5 . This cross - section is chosen for illustrative purposes because it clearly shows all the leakage paths. It should also be noted that the intersection occurs along the distance defined by the shoulders 158A, 158B outside the recesses 123A, 123B.

[0303] In the Figures 1 to 5 embodiment, there is one main rotor circumferential protrusion 134A, 134B and one auxiliary rotor circumferential protrusion 146A, 146B (on each side). In other embodiments, there can be 2, 3, or more such protrusions, all having the same radial extension, different from each other in their radial extension, two having the same radial span and one having a different radial span, etc.

[0304] The main rotor circumferential protrusions 134A, 134B and the auxiliary rotor circumferential protrusions 146A, 146B each have a tapered cross - section extending from their base to a rounded end. While this is typical, it is not the only configuration for such circumferential protrusions. Additionally, the rounded ends of the protrusions can have a circular cross - section, an ellipse, or a polygon, or generally any spline - like shape.

[0305] The radially - directed sections 150A, 150B extend generally radially, but are angled in a trajectory towards the main axis, which is designed such that thermally - induced radial and axial expansion differences will result in a minimal change in the width of the radially - directed sections, e.g., within the operating temperature range of the device, the change in width is less than about ±25%. In this embodiment, the trajectory of the radially - directed sections 150A, 150B defined by the relatively straight main portions of the outer surfaces 130A, 130B of the annular members 124A, 124B is about 81°.

[0306] As can be seen, the first segments 158A, 158B of the auxiliary rotor - associated fluid leakage paths 144A, 144B extending from the intersections 154A, 154B define a general trajectory away from the auxiliary axis 118. The angle between the segments 158A, 158B and the radially - directed sections 150A, 150B is about 90°.

[0307] As briefly mentioned above, the axial centrifugal force caused by increasing the rotational speed at the edge of the circumferential radial protrusion or at the apex of the arcuate sections 136A, 136B causes the components carried by the fluid (which may be one or more of the droplets, mists, or other particles carried by the leakage fluid) to accumulate at this apex or edge region. These components can accumulate at such apices and cause a film to form at such locations.

[0308] The leakage path can be configured such that the flow time of the leakage fluid from the annular restricted space has a travel time through the leakage path (e.g., due to branching), which is longer than the time for the pressure change in any angular portion of the restricted annular space caused by the rotation of the protruding element in the space. By designing one or both of the congruent surfaces to have a smaller deviation from the overall trajectory or by designing one of the congruent surfaces to have a cross-section slightly deviated from perfect congruence, the fluid leakage path can be designed to have an enlarged cross-section in the portion opposite the ridge of the circumferential protrusion. The change in width can cause a pressure drop in the leakage fluid flowing through the fluid leakage path and ultimately slow down the travel speed of the leakage fluid in the fluid leakage path.

[0309] The branching at the branch points 154A, 154B can cause the fluid to circulate in the forward or reverse direction between the branches, causing the fluid in the leakage path to remain there, neither escaping nor entering the restricted annular space 114. The leakage path branching into the auxiliary rotor-associated leakage paths 144A, 144B and the radially directed sections 150A, 150B at the branch points 154A, 154B can also be designed to cause a pressure drop and ultimately slow down the travel speed of the leakage fluid in the auxiliary rotor-associated leakage paths and the radially directed sections. Additionally, the sections of the auxiliary rotor-associated leakage paths 144A, 144B and / or the radially directed sections 150A, 150B (usually the sections near the intersections 154A, 154B) can have a three-dimensional surface structure configured to increase the friction of the leakage fluid flowing through this section. This can be in the form of surface irregularities such as surface wear, small indentations, or small protrusions. Such surface irregularities are typically at the sub-millimeter level.

[0310] Figure 6 An apparatus 200 according to another embodiment of the present disclosure is shown, where the fluid leakage path has an enlarged cross-section at portions 235, 235B opposite the ridges of the circumferential protrusions 234A, 234B. These portions of the leakage path with the enlarged cross-section will cause a local pressure drop in the leakage fluid flowing through the fluid leakage path, resulting in the condensation and deposition of a fluid film at this portion, and this fluid film acts as a seal, thereby hindering the leakage fluid from flowing through the fluid leakage path.

[0311] Figure 7 illustrates a device 300 according to another embodiment of the present disclosure. The main differences between the device 300 and the Figures 1 to 5 device 100 are as follows: (1) Instead of forming a single circumferential radial protrusion 146A, 146B on the auxiliary rotor 106 in the device 100, the auxiliary rotor 306 of the device 300 has one main circumferential radial protrusion 346A, 346B and three secondary circumferential radial protrusions 347A, 347B, and the secondary circumferential radial protrusions have a radial span smaller than that of the main circumferential radial protrusions 346A, 346B, where the radial span increases from the secondary circumferential radial protrusion closest to the circumferential radial protrusions 346A, 346B to the outermost secondary circumferential radial protrusion among the three secondary circumferential radial protrusions; and the difference is (2) Instead of forming a single circumferential radial protrusion 156A, 156B on the main rotor 104 in the device 100, the main rotor 306 of the device 300 has three circumferential radial protrusions 357A, 357B, and the radial span of the circumferential radial protrusions decreases from the largest circumferential radial protrusion near the outside 330A, 330B to the more outermost circumferential radial protrusion.

[0312] Figure 8 illustrates a device 400 according to another embodiment of the present disclosure. In the device 400, there are no circumferential radial protrusions on either the main rotor 404 or the auxiliary rotor 406. However, the proximal segment at the leakage path branches into two distal leakage paths that are different from each other at the branch point, allowing rotary seals 460A, 460B to be assembled at the ends of the leakage paths associated with the main rotor to further seal the leakage path and thereby prevent any remaining leakage fluid from passing through. Similarly, rotary seals 462A, 462B can also be assembled at the ends of the leakage paths associated with the auxiliary rotor, and seal the leakage path by preventing any remaining leakage fluid from flowing through the leakage path and thereby preventing any remaining leakage fluid from passing through.

[0313] Figure 9 illustrates a device 500 according to another embodiment of the present disclosure. The device has a general design similar to that of the Figures 1 to 5 device 100, where sealing elements 560A, 560B and 562A, 562B similar to those of the device 400 are added.

[0314] Figure 10 illustrates a device 600 according to another embodiment of the present disclosure. Although in all the previous embodiments described above, the stator is the outer peripheral member and the rotor is contained within the stator, this is reversed in the device 600, i.e., the stator 602 is the inner member of the two members and the rotor rotates around the stator.

[0315] Referring now to FIG. 11, which shows an apparatus 700 according to another embodiment of the present disclosure. Twelve auxiliary rotors 706 are disposed in a stator 702. A main rotor 704 is coupled to a gear 705 that meshes with the toothed end portions 707 of the auxiliary rotors 706. Through this gear drive, the main rotor 704 and the auxiliary rotors 706 can rotate in a synchronous manner.

Claims

1. An apparatus, comprising: a first part and a second part, one or both of the first part and the second part being capable of rotating in opposite directions about a main axis, the main axis defining an axial direction and a radial direction, one or more auxiliary rotors being assembled in the first part and capable of rotating about an auxiliary axis parallel to the main axis, the rotations being synchronous and jointly serving to compress, expand or pump a fluid in a restricted annular space formed between the first part and the second part; and a fluid leakage path formed between congruent opposing surfaces formed between each two of the first part, the auxiliary rotors and the second part; wherein the fluid leakage path is configured with an active sealing element that impedes the flow of fluid through the path during rotation, the active sealing element comprising one or more of the following (1) and (2): (1) a proximal section of the leakage path that extends out of the restricted annular space and is formed between an arcuate outer peripheral surface of a circumferential sidewall of the space defined by the second part and a congruent surface of the first part, and (2) an interrupted leakage path, wherein a proximal section of the fluid leakage path that extends out of the restricted annular space branches into two distal sections, the two distal sections comprising: (i) one or more auxiliary-rotor-associated leakage paths, each auxiliary-rotor-associated leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and a congruent surface of the first part; and (ii) a generally radially extending section of a second-part-associated leakage path formed between a member of the second part and a congruent surface of the first part.

2. An apparatus, comprising: a main rotor and a stator, the main rotor being capable of rotating about a main axis, the main rotor and the stator having respective annular rotor faces and annular stator faces that face each other and define a restricted annular space therebetween; two or more auxiliary rotors that are embedded in shape-matching receiving spaces within the stator, are radially disposed around the main rotor, and each engage the main rotor at a radially engaging sector, each auxiliary rotor being capable of rotating axially about an auxiliary axis parallel to the main axis and being configured to rotate synchronously with the main rotor and having a engaging portion that has an engaging abutment that abuts into the annular restricted space and is configured to roll in a sealing fit on the annular rotor face; a plurality of protruding elements that are disposed on the annular rotor face and extend from the annular rotor face into the restricted annular space and are capable of rotating with the main rotor within the restricted annular space, the protruding elements being configured to engage adjacent to and be received adjacent to in engaging grooves formed in the engaging abutment, the protruding elements jointly defining, in their rotation with the engaging portion, transient and volumetric change compartments for fluid intake, compression, expansion or discharge. A rotor having two annular members on opposite sides of the restricted annular space, each annular member having an inner face defining a sidewall of the restricted annular space and an outer face longer than the inner face, the outer face extending to a substantially axially extending base, the two walls being connected by an arcuate section; and A fluid leakage path formed between congruent opposing faces of each two of the main rotor, the auxiliary rotor, and the stator; wherein Each fluid leakage path in the fluid leakage paths includes a proximal section that extends in a substantially axial direction and is formed between a substantially arcuate face of one of the annular members and a congruent surface of the stator.

3. The apparatus according to claim 2, wherein the proximal section branches into two distal sections, the two distal sections consisting of: An auxiliary rotor associated leakage path, each leakage path extending in a substantially axial direction and formed between an auxiliary rotor of the auxiliary rotor and a congruent surface of the stator; and A substantially radially directed section of the main rotor associated leakage path.

4. The apparatus according to claim 3, wherein the branching causes leakage losses to flow back and accumulate to seal the fluid leakage path.

5. The apparatus according to claim 3 or 4, wherein the radially directed section is connected at its distal end to a distal section of the main rotor associated leakage path that extends in a substantially axial direction from the distal end.

6. The apparatus according to any one of claims 3 to 5, wherein the distal sections of the auxiliary rotor associated leakage path and the main rotor associated leakage path are radially separated relative to the main axis.

7. The apparatus according to claim 6, including one or both of the following: At least one main rotor protrusion, which is a circumferential radial protrusion that extends radially from the main rotor into a congruent receiving recess of the stator and is rotatable within the congruent receiving recess, and defines a tortuous distal section of the main rotor associated fluid leakage path, the tortuous distal section extending in a substantially radial direction and being connected to each other by sections extending along the edge of the at least one circumferential radial protrusion, and At least one auxiliary rotor protrusion, which is a circumferential radial protrusion that extends from the auxiliary rotor and is rotatable within the congruent receiving recess of the stator, and defines a tortuous auxiliary fluid leakage path, wherein the tortuous auxiliary fluid leakage path has sections defined around the circumferential radial protrusion.

8. The apparatus according to claim 7, including at least one of the main rotor protrusions and at least one of the auxiliary rotor protrusions.

9. The apparatus according to claim 7 or 8, wherein one or more of the circumferential radial protrusions have a tapered cross-section that extends from its base to a rounded end.

10. The apparatus according to any one of claims 3 to 9, wherein the radially directed section has a trajectory such that a thermally induced radial and axial expansion difference will result in a minimal change in the width of the gap between the opposing congruent surfaces of the section.

11. The apparatus according to claim 10, wherein the outer surface of the annular member of the main rotor has a substantially locus angled relative to the axis at about 80° to 81°.

12. The apparatus according to any one of claims 3 to 11, wherein the fluid leakage path associated with the auxiliary rotor has a proximal section at the branch, the proximal section defining a substantially locus away from the auxiliary axis.

13. The apparatus according to claim 12, wherein the angle between the section and the outer surface is about 90°.

14. The apparatus according to any one of claims 3 to 13, wherein the leakage path is configured such that the flow time of the fluid from the annular restricted space has a travel time through the leakage path that is longer than the time interval of the pressure change in any angular portion of the restricted annular space due to the rotation of the protruding element in the space.

15. The apparatus according to any one of claims 3 to 14, including one or more fluid seals in respective ones or more of the distal sections of the fluid leakage path.

16. An apparatus comprising: a main rotor and a stator, the main rotor being rotatable about a main axis, the main rotor and the stator having respective annular rotor faces and annular stator faces facing each other and defining a restricted annular space therebetween; two or more auxiliary rotors, the two or more auxiliary rotors being embedded in a shape-matching receiving space within the stator, radially disposed around the main rotor and each engaging the main rotor at a radially engaging sector, each auxiliary rotor being axially rotatable about an auxiliary axis parallel to the main axis and configured to rotate synchronously with the main rotor and having an engaging portion having an engaging abutment that abuts into the annular restricted space and is configured to roll in a sealingly adapted manner on the annular rotor face; a plurality of protruding elements, the plurality of protruding elements being disposed on the annular rotor face and extending from the annular rotor face into the restricted annular space and being rotatable within the restricted annular space together with the main rotor, the protruding elements being configured to engage adjacent to the annular stator face and being received adjacent in engagement grooves formed in the engaging abutment, the protruding elements jointly defining with the engaging portion in their rotation transient and volumetric change compartments for fluid intake, compression, expansion or discharge; a rotor having two annular members on both sides of the restricted annular space, each annular member having an inner surface defining a sidewall of the restricted annular space and an outer surface longer than the inner surface, the outer surface extending to a substantially axially extending base, the two walls being connected by an arcuate section; and a fluid leakage path formed between congruent opposing faces of each two of the main rotor, the auxiliary rotor and the stator; wherein Each fluid leakage path in the fluid leakage path includes a proximal section that extends in a generally axial direction and is formed between a generally arcuate surface of one of the annular members and a congruent surface of the stator; and wherein the proximal section branches into two distal sections, the two distal sections including (i) one or more auxiliary rotor-associated leakage paths, each auxiliary rotor-associated leakage path extending in a generally axial direction and formed between one of the auxiliary rotors and the congruent surface of the first part, and (ii) a generally radially extending section of the second part-associated leakage path formed between the member of the second part and the congruent surface of the first part.

17. The apparatus according to claim 16, wherein the branching causes leakage losses to flow back and accumulate to seal the fluid leakage path.

18. The apparatus according to claim 16 or 17, wherein the radially directed section is connected at its distal end to a distal section of the main rotor-associated leakage path that extends in a generally axial direction from the distal end.

19. The apparatus according to any one of claims 16 to 18, comprising one or both of the following: at least one main rotor protrusion, which is a circumferentially radial protrusion that extends radially from the main rotor into a congruent receiving recess of the stator and is capable of rotating within the congruent receiving recess, and defines a tortuous distal section of the main rotor-associated fluid leakage path, the tortuous distal section extending in a generally radial direction and being connected to each other by sections extending along the edge of the at least one circumferentially radial protrusion, and at least one auxiliary rotor protrusion, which is a circumferentially radial protrusion that extends from the auxiliary rotor and is capable of rotating within the congruent receiving recess of the stator, and defines a tortuous auxiliary fluid leakage path, wherein the tortuous auxiliary fluid leakage path has sections defined around the circumferentially radial protrusion.

20. The apparatus according to claim 19, comprising at least one main rotor protrusion of the main rotor protrusions and at least one auxiliary rotor protrusion of the auxiliary rotor protrusions.

21. The apparatus according to claim 19 or 20, wherein one or more of the circumferentially radial protrusions have a tapered cross-section that extends from its base to a rounded end.

22. The apparatus according to any one of claims 16 to 21, wherein the radially directed section has a locus such that a thermally induced radial-to-axial expansion difference will result in a minimal change in the width of the gap between the opposing congruent surfaces of the section.

23. The apparatus according to claim 22, wherein the outer surface of the annular member of the main rotor has a generally locus angled at approximately 80° to 81° relative to the axis.

24. The apparatus according to any one of claims 16 to 23, wherein the auxiliary rotor-associated fluid leakage path has a proximal section at the branch, the proximal section defining a generally locus away from the auxiliary axis.

25. The device according to claim 24, wherein the angle between the segment and the outer surface is about 90°.

26. The device according to any one of claims 16 to 25, including one or more fluid seals in respective ones of the distal segments of the fluid leakage path.

27. The device according to claim 26, wherein the seal includes a rotary seal element fitted at the end of the fluid leakage path.

28. A device comprising: a main rotor and a stator, the main rotor being rotatable about a main axis, the main rotor and the stator having respective annular rotor faces and annular stator faces facing each other and defining a restricted annular space therebetween; two or more auxiliary rotors, the two or more auxiliary rotors being embedded in a shape-matching receiving space within the stator, radially disposed around the main rotor and each engaging the main rotor at a radially engaging sector, each auxiliary rotor being axially rotatable about an auxiliary axis parallel to the main axis and configured to rotate synchronously with the main rotor and having an engaging portion having an engaging abutment that abuts into the annular restricted space and is configured to roll in a sealing fit on the annular rotor face; a plurality of protruding elements, the plurality of protruding elements being provided on the annular rotor face and extending from the annular rotor face into the restricted annular space and being rotatable with the main rotor within the restricted annular space, the protruding elements being configured to engage adjacent to the annular stator face and being received adjacent to each other in engagement grooves formed in the engaging abutment, the protruding elements jointly defining with the engaging portion in their rotation a transient and volumetric change compartment for fluid intake, compression, expansion or discharge; a rotor having two annular members on both sides of the restricted annular space, each annular member having an inner surface defining a side wall of the restricted annular space and an outer surface longer than the inner surface, the outer surface extending to a substantially axially extending base, the two walls being connected by an arcuate segment; and a fluid leakage path formed between congruent opposing faces of each two of the main rotor, the auxiliary rotors and the stator; wherein each fluid leakage path of the fluid leakage paths includes a proximal segment extending in a substantially axial direction and formed between a substantially arcuate face of one of the annular members and a congruent surface of the stator; and wherein the fluid leakage path includes one or more segments extending in a substantially radial direction and having a trajectory such that a thermally induced radial-to-axial expansion difference will result in a minimal change in the width of the segment.

29. The device according to claim 28, wherein one or more of the substantially radially directed segments are angled at about 80° to 81° relative to the axis.

30. The device according to claim 28 or 29, wherein one of the radially directed sections is a distal branch extending from a branch point where a proximal section extending in a substantially axial direction branches into two distal sections, the two distal sections including (i) one or more auxiliary rotor associated leakage paths, each auxiliary rotor associated leakage path extending in a substantially axial direction and formed between one of the auxiliary rotors and a congruent surface of the first part, and (ii) the substantially radially extending section formed between a member of the second part and the congruent surface of the first part.

31. The device according to any one of claims 28 to 30, wherein one of the radially directed sections is a radially directed section defined by at least one circumferential radial protrusion that extends radially from a rotating element into a congruent receiving recess of another element and is rotatable within the congruent receiving recess and defines a tortuous fluid leakage path, wherein sections of the tortuous fluid leakage path extend in a substantially radial direction and are connected to each other by sections extending along the edge of the at least one circumferential radial protrusion.

32. The device according to any one of claims 1 to 31, which is used as one or both of a compressor and an expander.

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