Step seal for refrigerant compressor

Abstract

In some aspects, the technology described herein relates to a refrigerant compressor comprising: a stator; a rotor configured to rotate relative to the stator; and at least one stepped seal located between the rotor and the stator, wherein the stepped seal comprises a first tooth and a second tooth extending from the rotor toward the stator, wherein a downstream surface of the first tooth and an upstream surface of the second tooth are arranged at an angle relative to each other, wherein the angle is less than 90°.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 133,471, filed January 4, 2021, and also claims the benefit of U.S. Provisional Application No. 63 / 224,479, filed July 22, 2021. The entire contents of Applications 63 / 133,471 and 63 / 224,479 are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the technical field of refrigerant compressors. Background Technology

[0003] A refrigerant compressor is used to circulate refrigerant in a refrigeration machine via a refrigerant circuit. A known refrigerant circuit includes a condenser, an expansion unit, and an evaporator. The compressor compresses the fluid, which then travels to the condenser, where it is cooled and condensed. The refrigerant then enters the expansion unit, which reduces the fluid's pressure, and finally reaches the evaporator, where the fluid evaporates, thus completing the refrigeration cycle.

[0004] Many refrigerant compressors are centrifugal compressors and have an electric motor that drives at least one impeller to compress the refrigerant. The fluid is then directed downstream for use in a refrigeration system. Known refrigerant compressors have seals. Summary of the Invention

[0005] In some aspects, the technology described herein relates to a refrigerant compressor comprising: a stator; a rotor configured to rotate relative to the stator; and at least one stepped seal located between the rotor and the stator, wherein the stepped seal includes a first tooth and a second tooth extending from the rotor toward the stator, wherein the downstream surface of the first tooth and the upstream surface of the second tooth are arranged at an angle relative to each other, wherein the angle is less than 90°.

[0006] In some aspects, the technology described herein relates to a refrigerant compressor as described above, wherein a first tooth and a second tooth constitute a pair of teeth, and a stepped seal comprises multiple pairs of teeth, wherein each pair of teeth is provided in a stepped arrangement.

[0007] In some aspects, the technology described herein relates to a refrigerant compressor, wherein a first tooth and a second tooth are formed in a rotor and an axial tooth is formed in a stator, and wherein the axial tooth extends radially outward from the first tooth and the second tooth in a generally axial direction.

[0008] In some aspects, the technology described herein relates to a refrigerant compressor, wherein a first tooth has a first point and a second tooth has a second point, and wherein the first point and the second point are arranged at a common radial position.

[0009] In some respects, the technology described herein relates to refrigerant compressors in which downstream and upstream surfaces meet at a curved surface to form a curved cavity.

[0010] In some aspects, the technology described herein relates to a refrigerant compressor in which a radial inner cavity wall is arranged downstream of a second tooth to form a second cavity located downstream of a curved cavity.

[0011] In some respects, the technology described herein relates to refrigerant compressors, wherein the second cavity is a curved cavity.

[0012] In some respects, the technology described herein relates to refrigerant compressors, wherein the second chamber is a square chamber.

[0013] In some aspects, the technology described herein relates to a refrigerant compressor in which the stator has a wear-resistant portion and wherein the first tooth and the second tooth extend toward the wear-resistant portion.

[0014] In some respects, the technology described herein relates to a refrigerant compressor in which the first and second teeth are configured to contact the wear-resistant portion and to etch tracks into the wear-resistant portion over time.

[0015] In some respects, the technology described herein relates to refrigerant compressors used in heating, ventilation, and air conditioning (HVAC) refrigeration systems.

[0016] In some aspects, the technology described herein relates to a refrigerant compressor, wherein a stator cavity is arranged in the stator, and the stator cavity is axially arranged between the first tooth and the second tooth.

[0017] In some aspects, the technology described herein relates to a refrigeration system comprising: a condenser; an evaporator; an expansion device; and a compressor, wherein the compressor includes a stator, a rotor configured to rotate relative to the stator, and at least one stepped seal located between the rotor and the stator, wherein the stepped seal includes a first tooth and a second tooth extending from the rotor toward the stator, wherein the downstream surface of the first tooth and the upstream surface of the second tooth are arranged at an angle relative to each other, wherein the angle is less than 90°.

[0018] In some respects, the technology described herein relates to a refrigeration system as described above, wherein the first tooth and the second tooth constitute a pair of teeth, and the stepped seal comprises multiple pairs of teeth, each pair of teeth being provided in a stepped arrangement.

[0019] In some aspects, the technology described herein relates to a refrigeration system in which a first tooth has a first point and a second tooth has a second point, and wherein the first point and the second point are arranged at a common radial position.

[0020] In some respects, the techniques described herein relate to refrigeration systems in which downstream and upstream surfaces meet at a curved surface to form a curved cavity.

[0021] In some aspects, the technology described herein relates to a refrigeration system in which a radial inner cavity wall is arranged downstream of a second tooth to form a second cavity located downstream of a curved cavity.

[0022] In some respects, the techniques described herein relate to refrigeration systems in which the second cavity is a curved cavity.

[0023] In some respects, the technology described herein relates to a refrigeration system in which the second cavity is a square cavity.

[0024] In some aspects, the technology described herein relates to a refrigeration system in which the stator has a wear-resistant portion, wherein a first tooth and a second tooth extend toward the wear-resistant portion, and wherein the first tooth and the second tooth are configured to contact the wear-resistant portion and etch tracks in the wear-resistant portion over time. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the refrigerant circuit.

[0026] Figure 2 A schematic diagram of a refrigerant compressor is shown.

[0027] Figure 3 A schematic diagram of an exemplary stepped sealing arrangement is shown.

[0028] Figure 4A An exemplary stepped sealing arrangement is shown.

[0029] Figure 4B It shows Figure 4A An exemplary stepped sealing arrangement.

[0030] Figure 5A Another exemplary stepped sealing arrangement is shown.

[0031] Figure 5B It shows Figure 5A An exemplary stepped sealing arrangement.

[0032] Figure 6A Another exemplary stepped sealing arrangement is shown.

[0033] Figure 6B It shows Figure 6A An exemplary stepped sealing arrangement.

[0034] Figure 7 A schematic diagram of another exemplary stepped sealing arrangement is shown.

[0035] Figure 8AAn exemplary stepped sealing arrangement is shown.

[0036] Figure 8B It shows Figure 8A An exemplary stepped sealing arrangement. Detailed Implementation

[0037] Figure 1 A refrigerant system is shown, comprising a compressor 10, a condenser 11, an evaporator 13, and an expansion device 15 arranged in a main refrigerant circuit or loop 17. This refrigerant system can be used, for example, in a refrigeration unit. In this example, a cooling tower may be in fluid communication with the condenser 11. While a specific example of a refrigerant system is shown, the application extends to other refrigerant system configurations, including those that do not include a refrigeration unit. For example, the main refrigerant circuit 17 may include an economizer located downstream of the condenser 11 and upstream of the expansion device 15. The refrigerant system may be, for example, part of a heating, ventilation, and air conditioning (HVAC) refrigeration system.

[0038] Figure 2 More details are shown from Figure 1 This is a part of a compressor 10, which in this example is a refrigerant compressor 10 (“compressor 10”). The compressor 10 includes a housing 12 that surrounds a motor 14. The housing 12 may include one or more components. The motor 14 rotates about axis A to drive at least one impeller to compress refrigerant. Example refrigerants include chemical refrigerants, such as R-134a, etc. The motor 14 may be driven by a variable frequency drive. The compressor 10 includes a first impeller 16 and a second impeller 18, each impeller being connected to the motor 14 via a shaft 19. In the illustrated example, impellers 16, 18 are centrifugal impellers. Although two impellers are illustrated, this disclosure extends to compressors having one or more impellers. In some embodiments, the compressor 10 may have two axial compression stages, or may have a mixed stage (i.e., a stage with radial and axial components) and an axial compression stage.

[0039] The housing 12 establishes the main refrigerant flow path F. Specifically, the housing 12 establishes the outer boundary of the main refrigerant flow path F. The first or primary refrigerant flow is configured to flow along the main refrigerant flow path F between the compressor inlet 20 and the compressor outlet 22. In the illustrated example, no inlet guide vanes are provided at the compressor inlet 20. The absence of inlet guide vanes reduces the number of mechanical parts in the compressor 10. In other examples, inlet guide vanes may be arranged near the inlet 20.

[0040] exist Figure 2From left to right, the main refrigerant flow path F begins at the compressor inlet 20, where refrigerant is drawn towards the first impeller 16. The first impeller 16 is disposed in the main refrigerant flow path F and is arranged upstream of the second impeller 18 relative to the main refrigerant flow path F. The first impeller 16 includes: an axially arranged inlet 16I, which is generally parallel to axis A; and a radially arranged outlet 16O, which is generally perpendicular to axis A.

[0041] In this example, immediately downstream of outlet 16O is a first bladed diffuser 24. The main refrigerant flow path F extends through diffuser 24 in a direction generally radially away from axis A. Next, the main refrigerant flow path F turns 180° in a cross-over bend 25 and flows radially inward through return channel 27 to the second impeller 18. Like the first impeller 16, the second impeller 18 includes an axially oriented inlet 18I and a radially oriented outlet 18O.

[0042] The compressor 10 has multiple seals 30A-30F. Seals 30A-30F prevent the main refrigerant from escaping from the flow path F. Seal 30A is located between the outer diameter of the first impeller 16 and the housing 12, and near the inlet 16I. Seal 30B is located between the first impeller 16 and the second impeller 18, between the shaft 19 and the housing 12. Seal 30C is located between the outer diameter of the second impeller 18 and the housing 12, and near the inlet 18I. Seal 30D is located between the inner diameter of the second impeller 18 and the motor 14. At least one of seals 30A-30D is a stepped seal. In one particular embodiment, all seals 30A-30D are stepped seals.

[0043] Stepped seals are used in turbomachinery to restrict or prevent the flow of fluid (e.g., liquid or gas) between adjacent internal compartments with different pressures. Stepped seals prevent fluid from flowing from a high-pressure location to a low-pressure location. A stepped seal typically includes multiple fins or teeth defining multiple cavities. These cavities trap the working fluid between moving and stationary components. Thus, the trapped fluid forms a barrier separating high-pressure areas from low-pressure areas within the machine. In one example, the stationary and moving components are a stator and rotor, such as an impeller. In another example, the stationary component may be provided by an insert within the compressor housing.

[0044] Figure 3An exemplary stepped seal 30 is schematically shown, representing any one of seals 30A-30D. A sealing flow path 32 is formed between the stator 38 and the rotor 40. In the illustrated embodiment, a plurality of teeth 42 extend generally radially outward from the rotor 40 in a direction toward the stator 38 (i.e., in a direction perpendicular to axis A) to define a plurality of cavities 48, 50 between the teeth 42 along the flow path 32. In another embodiment, the plurality of teeth 42 extend outward from the stator 38.

[0045] The teeth 42 on the rotor 40 are arranged in a stepped pattern, meaning that some teeth are positioned radially differently from the others. Specifically, in... Figure 3 In the rotor 40, teeth 42 are radially spaced by steps 44A. In the illustrated example, steps 44A are formed such that the teeth are arranged in pairs 60. Each pair 60 has a first tooth 42A and a second tooth 42B. The teeth 42A and 42B in each pair 60 are positioned in the same radial direction relative to the axis of rotation (i.e., axis A) of the rotor 40. In one example, steps 44A and teeth 42 are cut from the rotor 40 using known manufacturing techniques. Similarly, steps 44B are cut into the stator 38 to align with the rotor 40. Steps 44B may be formed, for example, by an insert within a housing. The insert may be metallic. In the illustrated example, each of steps 44A and 44B has seven. In other examples, each of steps 44A and 44B may have at least five. In yet another example, each of steps 44A and 44B may have ten or fewer. Tooth 42 and steps 44A, 44B introduce backflow, which delays the refrigerant flow (e.g., the trapping flow in cavities 48, 50) and helps reduce overall leakage.

[0046] Figure 4A More details of the stepped seal 30 are shown. Teeth 42A, 42B, 60, form two cavities 48, 50 of different shapes. Cavity 50 has a square shape, while cavity 48 has a circular shape. The first tooth 42A has an upstream surface 62 and a downstream surface 64. The second tooth 42B has an upstream surface 66 and a downstream surface 68. In this example, the upstream surface 62 of the first tooth 42A and the downstream surface 68 of the second tooth 42B form the wall of each cavity 50. Cavity 50 has a radially inner cavity wall 51. The cavity wall 51 is substantially parallel to axis A. The upstream surface 62 and the downstream surface 68 each extend radially outward from the cavity wall 51 at approximately a right angle. In other words, cavity 50 has a square bottom.

[0047] The downstream surface 64 of tooth 42A and the upstream surface 66 of tooth 42B form an angle with respect to the radial direction. Surfaces 64 and 66 join at a curved inner wall 47 to form a cavity 48. Cavity 48 is a curved cavity, while cavity 50 is a square cavity. Surfaces 64 and 66 are arranged relative to each other at an angle θ. Angle θ is less than 90°. In another example, angle θ is between 45° and 90°.

[0048] The upstream surface 62 and downstream surface 64 of the first tooth 42A meet at point 72A. The upstream surface 66 and downstream surface 68 of the second tooth 42B meet at point 72B. Points 72A and 72B are the outermost radial portions of the rotor 40 in each step. In this example, points 72A and 72B within each pair 60 extend radially to the same location. A radial clearance 80 is defined between points 72A and 72B and the stator 38. In one example, the radial clearance 80 is at least 0.15 mm. An axial clearance 82 is defined between the downstream surface 68 of the second tooth 42B and the upstream surface 62 of the adjacent pair of teeth 60. In one example, the axial clearance is at least 0.7 mm. An axially extending tooth 70 extends from the stator 38 in a generally axial direction. The axial tooth 70 extends from step 44B into the flow path. The axial tooth 70 may have an inner surface 74 and an outer surface 76. In one example, the inner surface 74 is substantially parallel to the axis of rotation A. Inner surface 74 and outer surface 76 are arranged relative to each other at an angle ψ. For example, the angle ψ is less than 60°. Inner and outer surfaces 74 and 76 extend in the upstream direction and meet at point 78. In one example, point 78 is aligned with point 72A in the axial direction.

[0049] Figure 4B Fluid flow through the stepped seal 30 is illustrated. As shown, radial teeth 42 and axial teeth 70 generate vortices in the fluid, thereby trapping the fluid in cavities 48, 50. While an exemplary seal 30 is shown, specific shapes and dimensions can be customized for specific compressor sizes, speeds, and refrigerants. Cavities 48, 50 provide recirculation areas within the refrigerant leakage path to help reduce leakage. Three sharp teeth 42A, 42B, 70 generate vortices 90, 92, 94 in the flow field. This tooth arrangement provides three recirculation areas 91, 93, 95 for each step to help passively control the flow, thereby reducing overall leakage and improving efficiency.

[0050] Figure 5A Another example of a stepped seal 130 is illustrated. Unless otherwise described or shown, the stepped seal 130 corresponds to... Figure 3 , 4AThe stepped seal 30 of 4B, wherein similar components have reference numerals prefixed with "1". In this example, the two teeth 142A, 142B in each pair 160 form two angled cavities 148, 150. The upstream surface 162 of the first tooth 142A extends from the radial inner cavity wall 151 at an angle α less than 90°. The downstream surface 168 of the second tooth 142B extends from the cavity wall 151 at a substantially right angle or perpendicular to axis A. Thus, the cavity 150 formed between adjacent tooth pairs 60 has an angled shape. The downstream surface 164 of the first tooth 142A and the upstream surface 166 of the second tooth 142B meet at a point defining an angle θ. For example, the angle θ can be less than 90°.

[0051] The upstream surface 162 and downstream surface 164 of the first tooth 142A meet at point 172A. The upstream surface 166 and downstream surface 168 of the second tooth 142B meet at point 172B. Points 172A and 172B within each pair 160 extend radially to the same position. In other words, points 172A and 172B touch the portion of the radial clearance between the rotor 140 and the stator 138.

[0052] An axially extending tooth 170 extends from the stator 138 in a generally axial direction. The axial tooth 170 extends from the step 144B into the flow path. The inner surface 74 of the axial tooth 170 is substantially parallel to the axis of rotation A. The inner surface 174 and the outer surface 176 of the axial tooth 170 are arranged relative to each other at an angle ψ. For example, the angle ψ is less than 60°. The inner surface 174 and the outer surface 176 extend in an upstream direction and meet at point 178. In one example, point 178 extends upstream of the first tooth 142A. In another example, point 178 is substantially aligned with the first tooth 142A in the axial direction.

[0053] Figure 5B Fluid flow through a stepped seal 130 is illustrated. The toothed arrangement provides three recirculation zones 191, 193, and 195 for each step. Three sharp teeth 142A, 142B, and 170 generate eddies 190, 192, and 194 in the flow field. In some examples, this arrangement passively controls flow to reduce overall leakage and can reduce leakage by 40–80% compared to known conventional seals.

[0054] Figure 6A Another exemplary stepped seal 230 is illustrated. Unless otherwise described or shown, stepped seal 230 corresponds to... Figure 3 , 4AThe stepped seal 30 of 4B, wherein similar components have a reference numeral "2" appended to its front. In this example, the stepped seal 230 reduces leakage flow by using a stepped arrangement and a wear-resistant material within the stepped seal. The performance of the seal 230 depends on the stepped design and the radial clearance at the tips of the teeth 242. In some known stepped seals, the amount of radial clearance can be difficult to control because factors such as thermal gradients, centrifugal forces, gas pressure, and shaft bending can cause deformation between components. The stator 238 includes a wear-resistant portion 246 formed of a wear-resistant material. In some examples, the wear-resistant portion 246 is an insert disposed within the compressor housing. The wear-resistant portion 246 helps to minimize the clearance between the tips of the teeth 242 and the stator 238. The wear-resistant portion 246 initially comes very close to the clearance between the rotor 240 and the teeth 242, and gradually wears away over time as the teeth 242 come into contact with the wear-resistant portion 246.

[0055] like Figure 6A As shown, the wear-resistant portion 246 wears away over time as the compressor 10 operates. Tracks 249 are etched into the radially outward-facing wear-resistant portion 246 of each tooth 242. Each tooth 242 has a flat tip 272 forming the track 249. As the rotor 240 rotates, the teeth 242 contact the wear-resistant portion 246, and some of the wear-resistant portion 246 is worn away in the track 249 where the teeth 242 contact the wear-resistant portion 246. The track 249 provides a very small gap between the teeth 242 and the stator 238. In other words, once the track 249 is formed by the teeth 242, a portion 253 of the wear-resistant material extends radially inward from the track 249 between the tracks 249. Due to the axial movement of the impellers 16, 18, the track 249 can be wider in the axial direction than the tip 272 of the teeth 242.

[0056] In this arrangement, the upstream surface 262 of the first tooth 242A and the downstream surface 268 of the second tooth 242B are substantially perpendicular to the radial inner cavity wall 251. Surfaces 262 and 268 meet the cavity wall 251 at a rounded edge to form a curved cavity 250. The downstream surface 264 of the first tooth 242A meets the upstream surface 266 of the second tooth 242B at a curved surface 247 to form a second curved cavity 248. Surfaces 264 and 266 are arranged relative to each other at an angle θ. In one example, the angle θ may be less than 90°. In another example, the angle θ is between 45° and 90°. For example, a specific tooth arrangement can be selected based on a specific compressor size and speed.

[0057] The wear-resistant portion 246 is formed of a wear-resistant material. Examples of wear-resistant materials may include polytetrafluoroethylene (“PTFE”), polyamide, and other low-strength alloys. The rotor 240 and teeth 242 are typically formed of a hard material that can wear away the wear-resistant portion 246, such as aluminum alloys, stainless steel, carbon steel, nickel alloys (e.g., Incol nickel alloy), etc. The wear-resistant portion 246 and the track 249 formed over time allow for minimal clearance dimensions, making it more difficult for flow to continue, thereby improving the sealing capability of the seal 230.

[0058] When the wear-resistant parts wear away, the use of wear-resistant materials can generate debris. Although the amount of wear may be small, the system may include high-precision parts. For example, bearings, sensors, and power electronics within the system must not have debris intrusion. In some examples, a debris catcher may be positioned downstream of tooth 242 to capture any debris from wear-resistant part 246 as it wears. The debris catcher may be positioned in the discharge path to redirect debris away from any sensitive components downstream of seal 230.

[0059] Figure 6B Fluid flow through the stepped seal 230 is illustrated. Compared to arrangements with rigid materials, the wear-resistant material provides a significantly smaller radial clearance, which further reduces leakage. The combination of two teeth 242A, 242B followed by a rounded rectangular cavity 250 provides a specific flow pattern with two vortices 290, 294 and two recirculation zones 291, 295. This recirculation arrangement reduces the total leakage flow. In some examples, this arrangement passively controls the flow to reduce total leakage and can reduce leakage by 40-80% compared to known conventional seals.

[0060] Figure 7 Another exemplary stepped seal 330 is illustrated. Unless otherwise described or shown, the stepped seal 330 corresponds to... Figure 3 , 4A The stepped seal 30 of 4B, wherein similar components have reference numerals prefixed with "3". In this example, teeth 342 on rotor 340 are radially spaced by steps 344A. In the illustrated example, steps 344A are formed such that the teeth are arranged in pairs 360. Each pair 360 has a first tooth 342A and a second tooth 342B. The teeth 342A, 342B in each pair 360 are in the same position in the radial direction relative to the axis of rotation (i.e., axis A) of rotor 340. A cavity 350 is formed between each pair of teeth 360, and a cavity 348 is formed between the teeth 342A, 342B within each pair 360.

[0061] Steps 344A, teeth 342, and cavities 350 are cut from the rotor 40 using known manufacturing techniques. A similar step 344B is also cut into the stator 338 to align with the rotor 340. In this example, a cavity 371 is formed in the stator 338 between the steps 344B. In some examples, cavities 371 form teeth 359 extending toward the rotor 340 within the stator 338. Teeth 359 may have a size and shape substantially similar to teeth 342A. Teeth 342, 359, and steps 344A, 344B introduce backflow, which delays refrigerant flow (e.g., trapping flow in cavities 348, 350, 371) and helps reduce overall leakage.

[0062] Figure 8A It shows Figure 7 An exemplary stepped sealing arrangement is provided. In this example, two teeth 342A, 342B in each pair 360 form two cavities 348, 350. Cavity 350 is formed between the upstream surface 362 of the first tooth and the downstream surface 368 of the second tooth 342B. In this example, the cavity wall 351 is rounded at its radially innermost portion. For example, the cavity wall 351 may have a semicircle or a radius. For example, the wall 355 opposite the rounded end of the cavity wall 351 may be substantially parallel to axis A. For example, the cavity 350 has a rectangular shape with rounded ends. Surfaces 362, 368 may extend substantially perpendicular to axis A. In some examples, tooth 359 may meet wall 355 at a fillet 357.

[0063] A cavity 348 formed between teeth 342A and 342B within a pair of teeth 360 has an angled shape. The downstream surface 364 of the first tooth 342A and the upstream surface 366 of the second tooth 342B are angled relative to axis A. The downstream surface 364 of the first tooth 342A and the upstream surface 366 of the second tooth 342B are arranged relative to each other at an angle θ. For example, the angle θ can be approximately 90°. In other examples, the angle θ can be less than 90°. A cavity 371 is formed in the stator 338 and is opposite to cavity 348. Cavity 371 can have a similar shape to cavity 348 and is substantially aligned with cavity 348. In one example, cavity 371 is a mirror image of cavity 348 with respect to a plane parallel to the axial direction and radially arranged between cavities 348 and 371.

[0064] The upstream surface 362 and downstream surface 364 of the first tooth 342A meet at end face 372A. The upstream surface 366 and downstream surface 368 of the second tooth 342B meet at end face 372B. End faces 372A and 372B within each pair 360 extend radially to the same position. The geometry of the flow path alters the velocity and trajectory of the fluid flow, which can reduce leakage through the seal.

[0065] Figure 8BFluid flow through a stepped seal 330 is illustrated. In this example, the arrangement of teeth and cavities provides three recirculation zones 391, 393, and 395 for each step as the fluid flows from left to right. The arrangement of teeth 342 and cavities 348, 350, and 371 generates eddies 390, 392, and 394 in the flow field. In some examples, this arrangement passively controls the flow to reduce overall leakage.

[0066] Any of the aforementioned stepped seals 30, 130, 230, and 330 can be used at any of the sealing positions 30A-30D. In some examples, different types of stepped seals 30, 130, 230, and 330 can be used at different sealing positions 30A-30D within the same compressor 10.

[0067] Although the different examples have the specific components shown in the illustrations, the embodiments of this disclosure are not limited to those specific combinations. Some components or features from one example may be used in combination with features or components from another example. Furthermore, the various drawings accompanying this disclosure are not necessarily drawn to scale, and some features may be enlarged or minimized to show certain details of a particular component or arrangement.

[0068] Those skilled in the art will understand that the above embodiments are exemplary and not restrictive. That is, modifications to this disclosure will fall within the scope of the claims. Therefore, the following claims should be studied to determine their true scope and content.

Claims

1. A refrigerant compressor, the refrigerant compressor comprising: stator; A rotor, the rotor being configured to rotate relative to the stator; and At least one stepped seal is located between the rotor and the stator, wherein the stepped seal includes a first tooth and a second tooth extending from the rotor toward the stator, wherein the downstream surface of the first tooth and the upstream surface of the second tooth are arranged at an angle relative to each other, wherein the angle is less than 90°, wherein the downstream surface and the upstream surface meet at a curved surface to form a rotor cavity, wherein the rotor cavity is defined by the downstream surface, the upstream surface and the curved surface, wherein the downstream surface of the first tooth extends from the curved surface along a direction having a radially outward component and an axially upstream component to a first point of the first tooth, wherein the upstream surface of the second tooth extends from the curved surface along a direction having a radially outward component and an axially downstream component to a second point of the second tooth, wherein the first point and the second point are arranged at a common radial position, wherein a stator cavity is arranged in the stator, wherein the stator cavity is axially arranged between the first tooth and the second tooth, wherein the stator cavity is a mirror image of the rotor cavity about a plane radially arranged between the rotor cavity and the stator cavity and extending parallel to the rotation axis of the rotor.

2. The refrigerant compressor according to claim 1, wherein, The first tooth and the second tooth constitute a pair of teeth, and the stepped seal includes multiple pairs of teeth, wherein each pair of teeth is provided in a stepped arrangement.

3. The refrigerant compressor according to claim 1, wherein, The first tooth and the second tooth are formed in the rotor, and the axial tooth is formed in the stator, wherein the axial tooth extends radially outward from the first tooth and the second tooth in a generally axial direction.

4. The refrigerant compressor according to claim 1, wherein, The rotor cavity is a curved cavity.

5. The refrigerant compressor according to claim 4, wherein, The radial inner cavity wall is arranged downstream of the second tooth to form a second cavity downstream of the curved cavity.

6. The refrigerant compressor according to claim 5, wherein, The second cavity is a curved cavity.

7. The refrigerant compressor according to claim 5, wherein, The second cavity is a square cavity.

8. The refrigerant compressor according to claim 1, wherein, The stator has a wear-resistant portion, wherein the first tooth and the second tooth extend toward the wear-resistant portion.

9. The refrigerant compressor according to claim 8, wherein, The first tooth and the second tooth are configured to contact the wear-resistant portion and etch a track in the wear-resistant portion over time.

10. The refrigerant compressor according to claim 9, wherein, Each track etched in the wear-resistant portion has an axial dimension larger than the axial dimension of the tip of the corresponding tooth in the first and second teeth.

11. The refrigerant compressor according to claim 1, wherein, The refrigerant compressor is used in heating, ventilation, and air conditioning refrigeration systems.

12. A refrigeration system, the refrigeration system comprising: Condenser; Evaporator; Expansion device; and The compressor is a refrigerant compressor according to any one of claims 1 to 11.

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