Non-lubricating compressor having a wear-resistant sealing element and a related assembly method of said compressor

Abstract

A non-lubricating compressor (10) for compressed gas comprises a fixed stator (12) having a housing (18) comprising a rotor cavity (20) defined by a bottom wall (22), an upper wall (24), and a side wall (26) connecting the bottom wall (22) and the upper wall (24), a rotor element (14) arranged to rotate about an axis (z) within the rotor cavity (20) to compress gas inside, and a self-supporting sealing element (16) arranged within the rotor cavity (20), wherein the sealing element (16) is formed of an abrasive carbon material and includes a wall portion (34) arranged on the inner surface of the side wall (26) in the rotor cavity (20).

Description

Technology Field

[0001] The present invention relates to a non-lubricating compressor for gas compression comprising a rotor cavity, a rotor element disposed within the rotor cavity, and a sealing element disposed within the rotor cavity and formed of an abrasion-resistant carbon material. Background Technology

[0002] Non-lubricated compressors do not use liquid lubricants to form a seal between the rotor and the housing. Generally, in known non-lubricated compressors, a wear layer of coating is applied to the functional surface, namely the surface of the rotor and / or the inner side of the wall defining the rotor cavity, and the wear layer of the coating tends to partially wear away during the compressor's operation to form a seal that is as tight as possible.

[0003] The disadvantage of these known embodiments is that the application of the abrasion-resistant coating is relatively time-consuming and the process is relatively expensive because it requires the lamination of multiple coating layers. Furthermore, the coating provides a limited margin allowing for machining tolerances, and consequently, the part must be manufactured to strict tolerance limits.

[0004] For example, an abrasive sealing element is proposed by the international patent application WO 2050 / 157567 A1 in the name of the present applicant. The said patent publication discloses a non-lubricating system comprising a stationary stator and a rotary rotor element, wherein an abrasive coating is provided on at least one side facing the rotor element of the sealing element included in the rotor cavity. Nevertheless, the sealing element presented by this publication covers the upper and lower walls of the rotor cavity but does not cover the side walls and does not provide a sufficient airtight seal. Furthermore, the sealing is not easily applicable to Wankel-type machines and, in particular, to Wankel compressors.

[0005] A three-dimensional sealing element formed of a non-wearing metal material for application to Wankel-type machines, particularly Wankel engines, is disclosed in U.S. patent application US 4021163 A. The problem to be solved

[0006] The objective of the present invention is to provide a non-lubricating compressor that does not suffer from the drawbacks of the prior art, in particular a non-lubricating compressor that is easy and inexpensive to manufacture, and at the same time is provided with sufficient airtight sealing elements. means of solving the problem

[0007] These and other objectives are achieved according to the present invention by a non-lubricating compressor according to claim 1 and a related assembly method of the said non-lubricating compressor according to claim 13.

[0008] Advantageous embodiments of the present invention are specified in dependent claims, the contents of which should be understood as an essential part of the description below.

[0009] In summary, the first aspect of the present invention is based on the concept of providing a non-lubricating compressor for gas compression, said compressor

[0010] A stationary stator having a housing comprising a rotor cavity defined by a bottom wall, an upper wall, and a side wall connecting the bottom wall and the upper wall,

[0011] A rotor element positioned to rotate about a z-axis within a rotor cavity to compress gas internally, preferably to move eccentrically about said z-axis, and

[0012] In a compressor comprising a self-supporting sealing element disposed within a rotor cavity,

[0013] The sealing element is formed of an abrasion-resistant carbon material, and

[0014] The sealing element is characterized by including a wall portion disposed on the inner surface of a side wall in the rotor cavity.

[0015] Herein, the expression “configured to rotate about an axis” as used in the description and in the appended claims includes both the state of an element configured to rotate simply about an axis and the state of an element configured to move eccentrically, that is, the state in which the element rotates about an axis that is not positioned at its center, as occurs in the case of a Wankel-type rotating machine.

[0016] Herein, the term “self-supporting” as used in the description and in the appended claims means that the sealing element is strong enough to be handled alone during the assembly of a non-lubricated compressor. Consequently, the sealing element may be manufactured separately and then inserted or fitted into the rotor cavity of the housing, and may be fastened to the rotor cavity, for example, by bonding, screwing, attaching, clamping, locking, or other means.

[0017] Herein, as used in the description and in the appended claims, the term “wearable carbon material” refers to a carbon material that wears away in powder form or a carbon material that is brittle in its mechanical behavior, namely, a carbon material in which fine particles are worn away through contact with the relevant end face of a rotating rotor element of a non-lubricated compressor. Ideally, such worn fine particles have a number average particle size of less than 1 μm.

[0018] The abrasive carbon material enables controlled wear during the operation of the system, taking into account the heat generated during the operation of the system, thereby wearing away the fine particles defined above. Accordingly, a sufficient amount of abrasive material is removed to allow proper rotation of the rotor element, and a layer of abrasive material with a thickness of, for example, 50 μm is removed from the sealing element until the abrasive material remaining on the sealing element provides a sufficiently airtight seal, that is, until the remaining gap is, for example, less than 10 μm.

[0019] According to a preferred embodiment of the present invention, a sealing element comprises a plate-shaped portion connected to or integral with a wall portion of the sealing element, and the plate-shaped portion is disposed on the inner surface of a bottom wall in the rotor cavity. Preferably, the sealing element further comprises another plate-shaped portion disposed on the inner surface of an upper wall in the rotor cavity. In this embodiment, the plate-shaped portion and the wall portion of the sealing element are preferably formed as a single piece, and more preferably, the other plate-shaped portion is provided as a separate cover component.

[0020] According to a preferred embodiment of the present invention, the wall portion of the sealing element has an inner surface facing the inside of the rotor cavity and an outer surface on the opposite side, and the inner surface has an epitrochoid shape or a hypotrochoid shape in a cross-section on a plane parallel to the bottom wall of the rotor cavity. In this embodiment, the outer surface of the wall portion in the sealing element preferably contacts the side wall of the rotor cavity entirely.

[0021] According to a preferred embodiment of the present invention, the self-supporting sealing element may preferably have a minimum thickness of at least 2 mm, more preferably at least 2.5 mm, and even more preferably at least 3 mm.

[0022] The sealing element is composed of a single layer made of, for example, abrasive carbon material, but in a given embodiment, the sealing element is composed of a layered structure formed of abrasive carbon material layers.

[0023] According to a preferred embodiment, the sealing element is formed at least partially from a carbon substrate, that is, the abrasion-resistant carbon material comprises or is composed of a carbon substrate. The carbon substrate is at least partially, preferably mostly, in the form of graphite, e.g., fine-grained graphite. According to an embodiment, the degree of graphitization is a PI defined as the possibility that adjacent hexagonal carbon layers have a graphite relationship of more than 60%, more than 80%, or more than 95%. X-ray diffraction spectroscopy provides a suitable method for determining the degree of graphitization.

[0024] The abrasive carbon material in the form of a carbon substrate according to the present invention is available through the carbonization of a synthetic material (e.g., carried out at a high temperature in the presence or absence of oxygen), wherein the synthetic material comprises a polymer substrate and carbon (e.g., in the form of carbon fibers or carbon particles). In the examples, the polymer is selected from the group consisting of polyester, vinyl ester, polyepoxide, polyphenol, polyimide, polyamide, polypropylene, and polyether ether ketone, and the polymer is a polyepoxide.

[0025] Preferably, the abrasive carbon material in the form of a carbon substrate according to the present invention can also be obtained by subjecting the aforementioned carbonized synthetic material to a separate graphite-forming step, such as high-temperature treatment—which increases the degree of graphitization. The abrasive carbon material in the form of a carbon substrate according to the present invention is optionally obtained by impregnating the carbonized synthetic material undergoing a separate graphite-forming step. The impregnation may be carried out by a metal, a salt, or a polymer.

[0026] In a preferred embodiment, the abrasive carbon material contains 80 weight%, 90 weight%, or 95 weight% of carbon.

[0027] According to a preferred embodiment, the preferred C2 Shore hardness of the abrasive carbon material in the sealing element is 60 to 70, and most preferably about 65. As used herein and known to those skilled in the art, “C2 Shore hardness” refers to the Shore hardness defined by the ASTM D2240 standard.

[0028] According to an embodiment of the present invention, the rotor element may be formed of stainless steel, preferably hardened stainless steel.

[0029] According to the most preferred embodiment of the present invention, the rotor cavity is a Wankel-type compression chamber, and the rotor element is a Wankel-type rotor configured for eccentric motion around a central axis nearly orthogonal to the bottom wall of the rotor cavity.

[0030] According to an embodiment of the present invention, at least a portion of the surface of the rotor element has a contact surface with a roughness Ra > 1.0 μm, preferably Ra > 2.5 μm. This can be achieved, for example, by roughening the end face using means known to those skilled in the art.

[0031] According to a preferred embodiment of the present invention, the sealing element may be provided with one or more openings for supplying and / or exhausting gas to and / or from the rotor cavity. That is, these openings form a passage for the inlet / outlet ports of the housing. In particular, at least one inlet opening and at least one outlet opening may be provided on the side wall and / or bottom wall of the sealing element for supplying the gas to be compressed and exhausting the compressed gas.

[0032] In addition, a second aspect of the present invention relates to a method for assembling a non-lubricating compressor according to the first aspect of the present invention, said method

[0033] a) a step of manufacturing a semi-finished sealing element by machining a block of abrasive carbon material such that the outer shape of the block replicates the inner shape of the rotor cavity, and the block has an open inner cavity defined by side walls and bottom walls having a constant thickness;

[0034] b) a step of heating the housing of the stator to a temperature of at least 350 ℃;

[0035] c) A step of inserting a semi-finished sealing element into the rotor cavity of the housing, provided that the housing is at least 350 ℃;

[0036] d) mounting the rotor element inside the inner cavity of the semi-finished sealing element; and

[0037] e) includes a step of operating the rotor element so that the inner cavity of the semi-finished sealing element is further machined by the rotor element.

[0038] The execution of step e) may be carried out for a predetermined period, for example, 5 to 15 minutes.

[0039] According to an embodiment of the present invention, the method may further include the step of roughening at least one end face in the rotor element.

[0040] According to an embodiment of the present invention, step c) may include the application of a sealant and / or adhesive and / or glue and / or thermal paste between the inner surface of the side wall in the housing and the sealing element to ensure or facilitate a sufficiently airtight seal between the sealing element and the inner surface of the wall of the rotor cavity in the housing and / or to bond the sealing element to the housing.

[0041] According to the most preferred embodiment of the above method, the rotor element is a Wankel-type rotor configured for eccentric motion around a central axis that is nearly orthogonal to the bottom wall of the rotor cavity, and much more preferably, step e) is performed in such a way that the inner surface of a sealing element having an epitrochoid or hypotrochoid shape in a cross section parallel to the bottom wall of the rotor cavity is obtained.

[0042] According to an embodiment of the above method, the method

[0043] f) After step c) or after step a) and before step d), further includes a step of machining the plate portion of the semi-finished sealing element until it has a constant thickness.

[0044] According to an embodiment of the above method, the method

[0045] g1) After step c), a step of machining at least one inlet opening that penetrates the sidewall of the sealing element and the sidewall of the rotor cavity by a single drilling step for supplying the compressed target gas; and

[0046] g2) After step c), the method further includes a step of machining at least one outflow opening that penetrates the sidewall of the sealing element and the sidewall of the rotor cavity by a single drilling step for exhausting compressed gas.

[0047] According to an embodiment of the above method, step c) may further include the step of applying an adhesive layer between the semi-finished sealing element and the rotor cavity.

[0048] Other features and advantages of the present invention will become clear from the following detailed description, given as a purely non-limiting example with reference to the accompanying drawings. Brief explanation of the drawing

[0049] FIG. 1 is a perspective view of a partial cross-sectional view of a non-lubricating compressor according to an embodiment of the present invention, and FIG. 2 is a perspective view of a partial cross-section of a sealing element in a non-lubricating compressor of FIG. 1, and FIG. 3 is a perspective view of a partial cross-section of the non-lubricated compressor of FIG. 1, in which a rotor element is shown. Specific details for implementing the invention

[0050] The present invention is described herein with reference to a number of preferred embodiments and the drawings, but the invention is not limited thereto in any way and is defined only by the claims. The drawings are intended to be schematic and non-limiting. In the drawings, the size of certain elements may not be depicted to actual scale for illustrative purposes. Dimensions and relative dimensions do not necessarily correspond to actual embodiments of the invention.

[0051] Referring to the drawings, the non-lubricating compressor according to the present invention has a reference numeral 10 It is represented as.

[0052] The compressor (10) as illustrated in the drawing is a non-lubricating system that compresses a gas or a mixture of gases, such as air. “Non-lubricating” means that no liquid is injected into the gas stream for lubrication, cooling, or sealing. Sealing of the rotor element to the rotor cavity of the housing is performed as described herein, but the compressor (10) may also include additional measures for sealing, such as sealing against the environment. Such additional measures are known to those skilled in the art and are therefore not described further here.

[0053] The compressor (10) according to the present invention basically includes a stationary stator (12), a rotor element (14), and a sealing element (16).

[0054] In a manner known as itself, the stationary stator (12) has a housing (18) containing a rotor cavity (20).

[0055] The rotor cavity (20) is defined by a bottom wall (22), a top wall (24), and a side wall (26) connecting the bottom wall (22) to the top wall (24). The bottom wall (22) has a basically flat surface facing the rotor cavity (20). In a preferred embodiment, the top wall (24) also has a basically flat surface facing the rotor cavity (20), and more preferably, the top wall (24) is parallel to the bottom wall (22). As illustrated in the drawing, in a preferred embodiment, the side wall (26) is orthogonal to both the bottom wall (22) and the top wall (24). The side wall (26) may be of any shape, but in a preferred embodiment, the side wall has a stadium shape, a discorectular shape, or an obround shape, that is, it comprises two flat wall sections facing each other and joined by a pair of opposing semicircular walls.

[0056] The rotor element (14) is positioned inside or within the rotor cavity (20) to compress the internal gas when rotating around the z-axis in a manner known as itself. As illustrated in FIG. 3, the rotor element (14) may be mounted on a rotor shaft (28) that rotates around the z-axis and may extend through the housing (18) on either side or one side, and may be driven to the shaft to rotate by the proper engagement of gears.

[0057] In the most preferred embodiment, the compressor (10) may be a Wankel-type compressor. Accordingly, in this embodiment, the rotor cavity (20) is formed as a Wankel-type compression chamber, and the rotor element (4) is a Wankel-type rotor. In a known manner, a Wankel-type rotor is similar in shape to a Reuleaux triangle and is configured for eccentric movement around the z-axis. Accordingly, the rotor element (14) may be configured for eccentric rotational movement around the z-axis that is nearly orthogonal to the bottom wall (22) of the rotor cavity (20).

[0058] In a manner known as itself, the compressor (10) supplies the gas to be compressed and supplies the compressed gas itself. In an embodiment, at least one inlet opening (30) and at least one outlet opening (32) are provided for supplying the gas to be compressed and exhausting the compressed gas, respectively. Preferably, both the at least one inlet opening (30) and the at least one outlet opening (32) are provided as through holes on the bottom wall (22) of the rotor cavity (20). As will be obvious to those skilled in the art, the at least one inlet opening (30) and the at least one outlet opening (32) are matched by each through hole formed through the thickness of the sealing element (16) so that gas can flow into and out of the rotor cavity (20). However, the at least one inlet opening (30) and / or the at least one outlet opening (32) may also be located at different parts of the rotor cavity (20). For example, in the embodiment illustrated in the drawing, a pair of inlet openings (30) are provided through the bottom wall (22) of the rotor cavity (20), and a pair of outlet openings (32) are provided through the side wall (26) of the rotor cavity (20).

[0059] The sealing element (16) is a self-supporting sealing element (16) and is positioned or fitted within the rotor cavity (20) or inside the rotor cavity to provide a sufficiently airtight seal between the rotor element (14) and the rotor cavity (20). To this end, the sealing element (16) includes a wall portion (34) positioned on the inner surface of a side wall (26) in the rotor cavity, preferably positioned to be in direct contact with said inner surface. 'Inner surface' here refers to a surface facing the inside of the rotor cavity (20).

[0060] The wall portion (34) of the sealing element (16) has an inner surface (34a) and an outer surface (34b), wherein the inner surface (34a) faces inward toward the rotor cavity (20) and the outer surface (34b) faces outward toward the rotor cavity, that is, positioned opposite the inner surface (34a) or on the opposite side of the wall portion (34). In the most preferred embodiment of the present invention, the inner surface (34a) has an epitrochoidal or hypotrochoidal shape in a cross-section of a plane parallel to the bottom wall (22) of the rotor cavity (20) or perpendicular to the z-axis around which the rotor element (14) rotates. The outer surface (34b) of the wall portion (34) in the sealing element (16) does not need to be parallel to the inner surface (34a). Nevertheless, in the preferred embodiment, the outer surface (34b) is in contact with the side wall (26) of the rotor cavity (20) completely or entirely. In this case, the outer surface (34b) of the wall portion (34) in the sealing element (16) can replicate the shape of the side wall (26), that is, it can be any shape, for example, but in a preferred embodiment, the outer surface has a stadium shape, a discorectular shape, or a non-circular shape, that is, it includes two flat wall portions facing each other and joined by a pair of opposing semicircular walls.

[0061] The sealing element (16) is shrink-fitted into the rotor cavity (20), and accordingly, the inner surface (34a) of the wall portion (34) replaces the surface of the side wall (26) in the rotor cavity (20) facing the contact portion, i.e., the inner surface or the inside of the rotor cavity (20)—on which the rotor element (14) would otherwise operate.

[0062] The sealing element (16) may further include a plate-shaped portion (36) disposed on the inner surface of the bottom wall (22) in the rotor cavity (20). The plate-shaped portion (36) may be connected to or integral with the remainder of the sealing element (16), i.e., the wall portion (34) of the sealing element (16) (i.e., formed as a single piece). When at least one inlet opening (30) and / or at least one outlet opening (32) is provided on the bottom wall (22) of the rotor cavity (20), the plate-shaped portion (36) of the sealing element is provided with individual through holes facing each of the at least one inlet opening (30) and / or at least one outlet opening (32) to allow gas to flow into and out of the rotor cavity (20).

[0063] In a preferred embodiment, the sealing element (16) may be disposed on the inner surface of the upper wall (24) in the rotor cavity (20), or may also include an additional plate-shaped portion (38) that contacts (at least partially) this inner surface. As an alternative to or in combination with the additional plate-shaped portion (38), a single layer or multilayer coating of abrasive carbon material may also be applied to the inner surface of the upper wall (24).

[0064] In a preferred embodiment, the plate portion (36) of the sealing element (16) and the wall portion (34) of the sealing element (16) are formed as a single piece or are integral with each other, whereas an additional plate portion (38) is provided as an individual component that covers and seals the rotor cavity (20). For example, the additional plate portion (38) may be attached to the inward side of the cover (40) of the housing (18) intended to close the rotor cavity (20).

[0065] In a preferred embodiment, the sealing element (16) has a minimum thickness of at least 2 mm, preferably at least 3 mm. This thickness is evaluated in the wall portion (34), and in the presence of the plate portion (36) and additional plate portion (38).

[0066] The sealing element (16) is formed from an abrasive carbon material, preferably formed entirely from an abrasive carbon material. In a preferred embodiment, the sealing element (16) comprises a layered structure formed from an abrasive carbon material. In a further preferred embodiment, the sealing element is formed from a carbon substrate as described above. Finally, the sealing element (16) preferably has a C2 Shore hardness of about 60 to about 70, more preferably about 65.

[0067] As expected, a second aspect of the present invention relates to a method of assembling a non-lubricating compressor (10) according to a first aspect of the present invention. The method is at least,

[0068] a) A step of manufacturing a semi-finished sealing element (16);

[0069] b) a step of heating the housing (18) of the stator (12);

[0070] c) a step of inserting a semi-finished sealing element (16) into the housing (18);

[0071] d) mounting the rotor element (14) inside the semi-finished sealing element (16); and

[0072] e) includes the step of operating the rotor element (14) so ​​that the semi-finished sealing element (16) is further machined by the rotor element (14).

[0073] In particular, step a) of manufacturing a semi-finished sealing element (16) is performed by machining a block of abrasive carbon material so that the outer shape of the block replicates the inner shape of the rotor cavity (20). In particular, the block is machined to have an upwardly open inner cavity defined by a bottom wall and a side wall having a constant thickness.

[0074] The housing (18) of the stator (12) is heated to a temperature of at least 350°C. As will be obvious to those skilled in the art, both the minimum temperature at which the housing (18) must be heated and the maximum temperature at which the housing can be heated depend on the coefficient of thermal expansion of the housing (18) material, the size of the housing (18), and the size of the semi-finished sealing element (16) that must be shrink-fitted inside the housing. Most preferably, the housing (18) is heated to a temperature ranging from 150°C to 450°C.

[0075] While the housing (18) is at a temperature of at least 350°C, the semi-finished sealing element (16) is fitted into the rotor cavity (20) of the housing (18). In fact, due to the high temperature of the housing (18), the size of the rotor cavity (20) will expand due to thermal expansion, and the semi-finished sealing element (16) will be easily fitted into the rotor cavity (20). Once the housing (18) is cooled back to room temperature, the size of the rotor cavity (20) returns to a smaller value. Thus, the semi-finished sealing element (16) is properly positioned and shrink-fitted into the rotor cavity (20), at which point the wall portion (34) presses against the side wall (26) of the rotor cavity (20).

[0076] In a preferred embodiment of the present invention, step c) of inserting a semi-finished sealing element (16) into the rotor cavity (20) may also include a step of applying an adhesive layer, a glue layer, or a thermal paste material layer between the semi-finished sealing element (16) and the rotor cavity (20), particularly between the side wall of the semi-finished sealing element (16) and the side wall of the rotor cavity (20).

[0077] In an embodiment relating to the method of the present invention, the semi-finished sealing element (16) may be further machined, for example, before step c) is performed to obtain a specific surface roughness value, i.e., before the semi-finished sealing element (16) is fitted into the rotor cavity (20).

[0078] In another embodiment of the method of the present invention, the plate portion of the semi-finished product element (16) is machined until it has a constant thickness or at least a surface facing the inner cavity of the semi-finished product sealing element (16) which is basically flat.

[0079] The rotor element (14) is mounted inside the inner cavity of the semi-finished sealing element (16), and accordingly, the rotor element operates so that when rotated, the inner cavity of the semi-finished sealing element (16) is further machined by the rotor element (14).

[0080] In a preferred embodiment, the rotor element (14) is a Wankel-type rotor arranged for eccentric movement, and accordingly, when step e) is executed, the rotor element (14) wears down the inner cavity of the semi-finished sealing element (16) and machines the inner surface (34a) of the sealing element (16) having an epitrochoid or hypotrochoid shape when cut into a cross section parallel to the bottom wall (22) of the rotor cavity (20) and basically orthogonal to the z-axis.

[0081] According to a preferred embodiment of the method of the present invention, the method may further include the step of machining at least one inlet opening (30) penetrating the wall (24) of the sealing element (16) and the side wall (26) of the rotor cavity (20) for supplying a compressed gas. Much more preferably, the opening penetrating the wall (34) of the sealing element (16) and penetrating the side wall (26) of the rotor cavity (20) is machined by a single drilling step, for example, by laser drilling, after or immediately after step c) is performed in a known manner.

[0082] In a similar manner, according to a preferred embodiment of the method of the present invention, the method may further include the step of machining at least one outflow opening (32) penetrating the wall (34) of the sealing element (16) and the side wall (26) of the rotor cavity (20) for exhausting compressed gas. Much more preferably, at least one outflow opening (32) penetrating the wall (34) of the sealing element (16) and penetrating the side wall (26) of the rotor cavity (20) is machined by a single drilling step, for example, laser drilling, after or immediately after step c) is performed in a known manner.

[0083] As is evident from the foregoing description, the non-lubricating compressor according to the present invention has a number of advantages.

[0084] By providing abrasion-resistant carbon material as a self-supporting sealing element rather than applying one or more abrasion-resistant coating layers to the inner walls of the housing, the fabrication and / or assembly of the housing is simplified, time and cost are saved, and a more airtight seal is provided for non-lubricated compressors.

[0085] Furthermore, due to the self-supporting nature of the sealing element (which eliminates the need to directly apply an abrasion coating to the relevant parts of the housing), materials with higher thermal resistance and / or better corrosion resistance can be used for the abrasion coating, thereby obtaining a seal that is more resistant to high operating temperatures and / or corrosion, which can extend the lifespan of non-lubricated systems. More specifically, the self-supporting element provides corrosion protection for the parts of the housing covered by this element, which provides better protection against corrosion than a coating when the latest technology is available. The achievable higher thermal resistance ensures usability at higher temperatures. In the aforementioned systems, higher temperatures are primarily the result of higher inlet temperatures and / or higher pressure ratios. Consequently, higher thermal resistance enables an extended operating range. However, mechanical robustness within the thermal capacity of the material still determines the service life. Higher thermal resistance is achieved by using carbon materials or carbon-based materials as described herein, instead of modern organic coatings. In addition, possible application of a glue layer and / or thermal paste between the sealing element and the rotor cavity facilitates heat transfer, thereby further improving the overall thermal resistance of the compressor.

[0086] Of course, without prejudice to the principles of the present invention, embodiments and details of the configuration may be broadly modified with respect to those described and illustrated merely as non-limiting examples, without departing from the scope of the present invention as defined by the appended claims.

Claims

Claim 1 A non-lubricating compressor (10) for gas compression, comprising a fixed stator (12) having a housing (18) including a rotor cavity (20) defined by a bottom wall (22), an upper wall (24), and a side wall (26) connecting the bottom wall (22) and the upper wall (24); a rotor element (14) arranged to rotate about an axis (z) within the rotor cavity (20) to compress gas inside; and a self-supporting sealing element (16) arranged within the rotor cavity (20), wherein the sealing element (16) is formed of an abrasive carbon material and the sealing element (16) includes a wall portion (34) arranged on the inner surface of the side wall (26) in the rotor cavity (20). Claim 2 A non-lubricating compressor according to claim 1, wherein the sealing element (16) further comprises a plate-shaped portion (36) connected to or integral with the wall portion (34) of the sealing element (16), and said plate-shaped portion (36) is disposed on the inner surface of the bottom wall (22) in the rotor cavity (20). Claim 3 A non-lubricating compressor according to claim 1 or 2, wherein the wall portion (34) of the sealing element (16) has an inner surface (34a) facing the inside of the rotor cavity (20) and an outer surface (34b) on the opposite side, and the inner surface (34a) has an epitrochoid shape in a cross section in a plane parallel to the bottom wall (22) of the rotor cavity (20) or a plane orthogonal to the central axis (z). Claim 4 In paragraph 3, the outer surface (34b) of the wall portion (34) in the sealing element (16) is in contact with the side wall (26) of the rotor cavity (20) in its entirety, in a non-lubricating compressor. Claim 5 A non-lubricating compressor according to paragraph 2, wherein the sealing element (16) further comprises another plate-shaped part (38) disposed on the inner surface of the upper wall (24) in the rotor cavity (20). Claim 6 A non-lubricating compressor according to claim 5, wherein the plate portion (36) and the wall portion (34) of the sealing element (16) are formed as one piece, and the other plate portion (38) is provided as a separate cover component. Claim 7 A non-lubricating compressor according to claim 1 or 2, wherein the sealing element (16) has a minimum thickness of at least 2 mm or at least 3 mm. Claim 8 A non-lubricating compressor according to claim 1 or 2, wherein the sealing element (16) includes a layered structure. Claim 9 A non-lubricating compressor according to claim 1 or 2, wherein the sealing element (16) is formed at least partially from a carbon substrate in the form of graphite or fine-grained graphite. Claim 10 A non-lubricating compressor according to claim 1 or 2, wherein the sealing element (16) has a C2 Shore hardness of 60 to 70 or 65. Claim 11 A non-lubricating compressor according to claim 1 or 2, wherein the rotor cavity (20) is a Wankel-type compression chamber and the rotor element (14) is a Wankel-type rotor configured for eccentric movement around a central axis (z) perpendicular to the bottom wall (22) of the rotor cavity (20). Claim 12 A non-lubricating compressor according to claim 1 or 2, wherein at least one inlet opening (30) and at least one outlet opening (32) are provided in the side wall, bottom wall (22) of the rotor cavity (20) or both for supplying and exhausting gas, respectively. Claim 13 A method for assembling a non-lubricating compressor (10) according to claim 1 or 2, comprising: a) manufacturing a semi-finished sealing element (16) by machining a block of abrasive carbon material such that the outer shape of the block replicates the inner shape of the rotor cavity (20) and the block has an open inner cavity defined by side walls and bottom walls having a certain thickness; b) heating the housing (18) of the stator (12) to a temperature of at least 350°C; c) inserting the semi-finished sealing element (16) into the rotor cavity (20) of the housing (18) while the housing (18) is at a temperature of at least 350°C; and d) mounting a rotor element (14) into the inner cavity of the semi-finished sealing element (16). and e) a method for assembling a non-lubricating compressor comprising the step of operating a rotor element (14) so ​​that the inner cavity of a semi-finished sealing element (16) is further machined by the rotor element (14). Claim 14 A method for assembling a non-lubricating compressor according to claim 13, wherein the rotor element (14) is a Wankel-type rotor configured for eccentric movement around an axis (z), and step e) is performed to obtain an inner surface (34a) of a sealing element (16) having an epitrochoidal shape in a cross-section in a plane parallel to the bottom wall (22) of the rotor cavity (20) or in a plane perpendicular to the axis (z). Claim 15 A method for assembling a non-lubricating compressor (10) according to claim 2, comprising: a) manufacturing a semi-finished sealing element (16) by machining a block of abrasive carbon material such that the outer shape of the block replicates the inner shape of the rotor cavity (20) and the block has an open inner cavity defined by side walls and bottom walls having a constant thickness; b) heating the housing (18) of the stator (12) to a temperature of at least 350°C; c) inserting the semi-finished sealing element (16) into the rotor cavity (20) of the housing (18) while the housing (18) is at least 350°C; d) mounting a rotor element (14) into the inner cavity of the semi-finished sealing element (16); e) operating the rotor element (14) so ​​that the inner cavity of the semi-finished sealing element (16) is further machined by the rotor element (14); and f) a method for assembling a non-lubricating compressor comprising the step of machining the plate portion (36) of the semi-finished sealing element (16) until it has a constant thickness after step c) or before step d). Claim 16 A method for assembling a non-lubricating compressor according to claim 13, further comprising: g1) a step after step c) of machining at least one inlet opening (30) that penetrates the wall (34) of the sealing element (16) and the side wall (26) of the rotor cavity (20) by a single drilling step for supplying the gas to be compressed; and g2) a step after step c) of machining at least one outlet opening (32) that penetrates the wall (34) of the sealing element (16) and the side wall (26) of the rotor cavity (20) by a single drilling step for exhausting the compressed gas. Claim 17 A method for assembling a non-lubricating compressor according to claim 13, wherein step c) further comprises the step of applying an adhesive layer between the semi-finished sealing element (16) and the rotor cavity (20).

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