Predicting tip seal wear in scroll pump

Abstract

A scroll pump or pumping system is configured to determine or predict whether a first scroll tip seal and / or a second scroll tip seal is a worn tip seal that should be replaced with a new tip seal. The determination or prediction is based on durations of run times during which the scroll pump operates in different, respective pressure ranges of pump inlet pressure, and durations of expected service lives of the scroll tip seals when operating in the respective pressure ranges.

Description

TECHNICAL FIELD

[0001] The present invention relates to scroll pumps, particularly to maintenance or servicing of scroll pumps, and more particularly to replacement of tip seals of scroll pumps.BACKGROUND

[0002] Scroll pumps are widely utilized as compressors for supplying a pressurized working fluid (e.g., compressed air, refrigerant, etc.) and as vacuum pumps for evacuating a chamber by removing a working fluid from the chamber. As appreciated by the skilled artisan, a scroll pump has at least one pumping (or compression) stage formed by an orbiting scroll and a fixed (stationary) scroll. The orbiting scroll has an orbiting scroll blade extending in an axial direction from a radially oriented orbiting scroll plate (or base) toward the fixed scroll. The fixed scroll has a fixed scroll blade extending in the opposite axial direction from a radially oriented fixed scroll plate (or base) toward the orbiting scroll. The scroll blades (or “wraps”) are spiral-shaped. That is, each scroll blade runs along a spiral path in multiple revolutions around the central region of its corresponding scroll plate. The orbiting and fixed scroll blades are nested with each other. The scroll pump further has a motor-driven crankshaft that rotates about its central shaft axis, or drive axis. The crankshaft has an eccentrically positioned crank located at the end of the crankshaft that is opposite to the motor. The central axis of the crank is radially offset from the drive axis of the main part of the crankshaft. Thus, as the main part of the crankshaft rotates about the drive axis, the crank orbits in a circle (whose radius corresponds to the radial offset distance) around the drive axis. The orbiting scroll is coupled to the crank and thus orbits with the crank, but without the orbiting scroll itself rotating on its own axis.

[0003] In operation, the orbiting scroll is driven by the crankshaft to orbit around the drive axis relative to the fixed scroll to create one or more moving, variable-volume pumping chambers or zones, also referred to as “pockets”, between the orbiting scroll blade and the fixed scroll blade. Each pocket is defined between and bounded by adjacent sections of the orbiting scroll blade and the fixed scroll blade. As the orbiting scroll orbits, the pockets receive the (gas-phase or liquid-phase) working fluid from a pump inlet and displace (transport or convey) the working fluid to a pump outlet. As the pockets move in accordance with the orbiting motion, the volume of the space inside the pockets decreases, thereby compressing the working fluid to some degree as the working fluid is being displaced toward the pump outlet.

[0004] An example of the structure and operation of such a scroll pump is described in U.S. Pat. No. 5,855,473, the entire contents of which are incorporated by reference herein.

[0005] A scroll pump may have more than one pumping stage, such as two pumping stages fluidly connected in series. For example, the orbiting scroll may be positioned between two fixed scrolls, namely, a fixed outboard scroll having a fixed outboard scroll blade and a fixed inboard scroll having a fixed inboard scroll blade. In this case, the orbiting scroll has one orbiting scroll blade on its inboard side and another orbiting scroll blade on its outboard side. The orbiting outboard scroll blade is nested with the fixed outboard scroll blade to cooperatively define one (outboard) pumping stage, and the orbiting inboard scroll blade is nested with the fixed inboard scroll blade to cooperatively define another (inboard) pumping stage, In operation, the first pumping stage (either the outboard stage or the inboard stage, depending on configuration) receives the working fluid from the pump inlet, compresses the working fluid, and transfers the compressed working fluid to the second pumping stage. The second pumping stage further compresses the working fluid and discharges the further compressed working fluid toward the pump outlet. An example of such a two-stage scroll pump is described in above-referenced U.S. Pat. No. 5,855,473.

[0006] In either a single-stage or multi-stage scroll pump, the orbiting scroll and the fixed scroll(s) may not contact each other. Instead, small axial gaps exist between the blade tips (free ends) of each scroll blade and the surfaces of the scroll plates that are immediately axially adjacent to and facing those corresponding blade tips. For example, on a given (outboard or inboard) side of the orbiting scroll plate, the blade tip of the orbiting scroll blade is spaced from the surface of the fixed scroll plate by an axial gap. Likewise, on the same side, the blade tip of the fixed scroll blade is spaced from the surface of the orbiting scroll plate by an axial gap. The axial gaps are necessary so that the orbiting scroll may move with respect to the fixed scroll(s). The scroll pump may be a “dry” scroll pump, meaning that it is not sealed or lubricated by a liquid such as oil. In this case, the axial gaps are closed and sealed by tip seals mounted to the respective blade tips, such that each tip seal runs continuously along the same spiral path as its corresponding scroll blade. The tip seals enhance the sealing interfaces between the orbiting scroll and the fixed scroll(s) without impairing the motion of the orbiting scroll.

[0007] In an alternative configuration, a scroll pump may be configured as a co-rotating scroll pump. In this case, for a given pumping stage, both scrolls orbit relative to each other. The scroll directly powered by the drive shaft may be termed the drive scroll and the other scroll may be termed the driven scroll. An example of a co-rotating scroll pump is described in U.S. Pat. No. 5,256,042, the entire contents of which are incorporated by reference herein.

[0008] In all types of dry scroll pumps utilizing tip seals, the tip seals wear down with pump operation over time due to sliding contact (e.g., rubbing) between the tip seals and the opposing, adjacent surfaces of the corresponding scroll plates (with the sliding contact occurring at least intermittently). Hence, the tip seals eventually and periodically need to be replaced with new tip seals, which requires at least partially disassembling the pump head to gain access to the tip seals. It would be desirable to know when a tip seal should be changed at a point in time before the tip seal wears to a point where the scroll pump starts to lose its vacuum performance. In certain applications, it can be very costly and undesirable to have an unplanned shutdown due to the need to replace a worn tip seal.

[0009] In view of the foregoing, there is a need for solutions regarding the replacement of tip seals in scroll pumps.SUMMARY

[0010] To address the foregoing problems, in whole or in part, and / or other problems that may have been observed by persons skilled in the art, the present disclosure provides methods, processes, systems, apparatus, instruments, and / or devices, as described by way of example in implementations set forth below.

[0011] According to one implementation, a method for replacing a tip seal in a scroll pump (e.g., a scroll pump assembly, or at least a scroll pump head thereof) includes: providing a scroll pump comprising a pump inlet, a pump outlet, and a pumping stage, wherein the pumping stage comprises a first scroll and a second scroll nested together, at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to pump fluid from the pump inlet to the pump outlet, the first scroll comprises a first scroll tip seal, and the second scroll comprises a second scroll tip seal; operating the scroll pump for a plurality of run times in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges; measuring a duration of each run time; determining the pump inlet pressure during the operating of the scroll pump for each of the amounts of run time; and determining that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal. The determination is based on: the duration of each run time measured; and respective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges.

[0012] According to another implementation, a scroll pump (e.g., a scroll pump assembly, or at least a scroll pump head thereof) includes: a pump inlet; a pump outlet; a pumping stage comprising a first scroll and a second scroll nested together, at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to pump fluid from the pump inlet to the pump outlet; a first scroll tip seal mounted to the first scroll; a second scroll tip seal mounted to the second scroll; a sensor configured to measure pump inlet pressure or to measure an operating parameter from which the pump inlet pressure can be calculated; a runtime meter configured to measure a plurality of run times during which the scroll pump operates in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges; and a controller configured to determine that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal. The determination is based on: the duration of each run time measured; and respective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges.

[0013] According to another implementation, a non-transitory computer-readable medium includes instructions stored thereon, that when executed on a processor, control or perform one or more of the steps of any of the methods disclosed herein.

[0014] Other devices, apparatus, systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention can be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.

[0016] FIG. 1 is a cross-sectional elevation view of an example of a scroll pump (assembly) in which the subject matter disclosed herein may be implemented.

[0017] FIG. 2 is a cross-sectional elevation view of an example of a pump head for a scroll pump according to an implementation of the present disclosure.

[0018] FIG. 3 is a cross-sectional perspective view of an orbiting scroll included with the pump head illustrated in FIG. 2.

[0019] FIG. 4 is a cross-sectional plan view (in the transverse plane) of a pumping stage of the pump head illustrated in FIG. 2.

[0020] FIG. 5 is a close-up view of a region of two pumping stages of the pump head illustrated in FIG. 2.

[0021] FIG. 6 is a schematic view of an example of a vacuum pumping system according to an implementation of the present disclosure.

[0022] FIG. 7 is a schematic view of a system controller for a vacuum pumping system according to an implementation of the present disclosure.

[0023] FIG. 8 is a flow diagram illustrating an example of a method for replacing a tip seal in a scroll pump according to an implementation of the present disclosure.

[0024] The illustrations in all of the drawing figures are considered to be schematic, unless specifically indicated otherwise.DETAILED DESCRIPTION

[0025] In this disclosure, all “implementations,”“aspects,”“examples,” and “embodiments” described are considered to be non-limiting and non-exclusive. Accordingly, the fact that a specific “implementation,”“aspect,”“example,” or “embodiment” is explicitly described herein does not exclude other “implementations,”“aspects,”“examples,” and “embodiments” from the scope of the present disclosure even if not explicitly described. In this disclosure, the terms “implementations,”“aspect,”“example,” and “embodiment” are used interchangeably, i.e., are considered to have interchangeable meanings.

[0026] In this disclosure, the term “substantially,”“approximately,” or “about,” when modifying a specified numerical value, may be taken to encompass a range of values that include + / −10% of such numerical value, unless specifically indicated otherwise.

[0027] FIG. 1 is a cross-sectional elevation view of an example of a scroll pump (assembly) 100 in which the subject matter disclosed herein may be implemented. The scroll pump 100 may be configured for use as a vacuum pump or as a compressor, as appreciated by persons skilled in the art. The type of working fluid pumped by the scroll pump 100 depends on the application for which the scroll pump 100 is utilized. The working fluid is often a gas (or mixture of gases) such as, for example, air, oxygen, nitrogen, a noble gas (e.g., helium, argon, etc.), a gas-phase compound (e.g., carbon dioxide, a refrigerant, etc.), a gas utilized in a chemical, manufacturing, or analytical process, or in applications requiring compressed air, etc. Alternatively, the working fluid may be a liquid such as may be utilized in a chemical, manufacturing, or analytical process, or a refrigerant in cooling applications, etc. The structure and operation of scroll pumps are generally understood by persons skilled in the art, and thus the scroll pump 100 and certain components thereof are described only briefly herein to provide a context for the presently disclosed subject matter.

[0028] The scroll pump 100 includes a pump head 102 powered by a motor 104. Typically, the motor 104 is an electric motor that includes a motor rotor (not shown) driven to rotate relative to a motor stator (not shown) by a magnetic field established between the motor rotor and motor stator by permanent magnets and / or electromagnets provided with the motor rotor and motor stator, as appreciated by persons skilled in the art. The motor rotor is coupled to a motor (output) shaft 108 that thus rotates with the motor rotor. The motor shaft 108 is coupled to a crankshaft 112 by an appropriate shaft coupling 116 such that the crankshaft 112 is driven to rotate by the motor rotor via the motor shaft 108 and shaft coupling 116. The shaft coupling 116 may be a mechanical coupling (e.g., shaft joint, spider coupling, etc.) or a non-contact type of coupling such as an axially- or radially-oriented magnetic coupling, as appreciated by persons skilled in the art. Alternatively, the pump head 102 and motor 104 are directly coupled by a single drive shaft instead of utilizing a separate motor shaft 108, crankshaft 112 and intermediate shaft coupling 116. The motor shaft 108 and at least a main portion of the crankshaft 112 rotate concentrically or coincidently about a central drive axis D.

[0029] The pump head 102 includes a pump frame 120, which may be a single-part construction or a multi-part construction in which two or more separate frame parts may be assembled to each other and disassembled from each other (e.g., for performing maintenance on the scroll pump 100). The pump frame 120 may be configured to serve as a pump housing that encloses various components of the pump head 102, and / or as a structural support to which various components are attached or with which various components are integral. The pump head 102 further includes one or more pumping elements configured to define one or more pumping (or compression) stages 124. At least one of the pumping elements is coupled to and driven to move by the crankshaft 112. In the implementations described herein, the pumping elements are scrolls as described in more detail below. The pump head 102 further includes a pump inlet 128 and an inlet conduit 132 (e.g., one or more passages, pipes, tubes, chambers, manifolds, plenums, headers, etc.) configured to direct a flow of incoming (aspirated) working fluid (the fluid being pumped) from the pump inlet 128 to the pumping stage(s) 124. The pump head 102 further includes a pump outlet 136 and an outlet conduit 140 (e.g., one or more passages, pipes, tubes, chambers, manifolds, plenums, headers, etc.) configured to direct a flow of outgoing (discharged) working fluid from the pumping stage(s) 124 to the pump outlet 136. Accordingly, the pump head 102 (particularly the pumping stage(s) 124) is configured to transport (or displace by pumping action) the working fluid from the pump inlet 128, through the inlet conduit 132, through the pumping stage(s) 124 and through the outlet conduit 140, and to the pump outlet 136, as indicated by an arrow F in FIG. 1. The inlet side of the pumping stage(s) 124 is the low-pressure (or vacuum) side and the outlet side of the pumping stage(s) 124 is the high-pressure side (the term “high” being relative to the term “low”).

[0030] The pump inlet 128 and / or the pump outlet 136 may include fittings as needed for fluidly connecting the pump head 102 to components (e.g., conduits, chambers, etc.) external to the scroll pump 100. For example, in the case of a vacuum pump, the pump inlet 128 may be configured to be fluidly coupled to a vacuum chamber (i.e., a chamber or enclosed space to be evacuated; see FIG. 6) and, depending on the application, the pump outlet 136 may discharge compressed fluid directly to the ambient or may be configured to be fluidly coupled to an appropriate receptacle for containing the discharged fluid. In the case of a compressor, the pump inlet 128 may be configured to be fluidly coupled to an upstream part of a system that circulates the working fluid (e.g., a heat exchanger or refrigeration system) or to intake ambient air (e.g., in the case of an air compressor), and the pump outlet 136 may be configured to be fluidly coupled to a device, tool or system that utilizes compressed fluid (i.e., is a consumer of compressed fluid, such as an air-powered tool). Such a downstream entity that receives compressed fluid from the scroll pump 100 may be referred to generally as a “destination” fluidly communicating with the pump outlet 136.

[0031] For purposes of reference and description, terms such as “axial” and “axially” are taken relative to the drive axis D. The drive axis D may be extended in either direction and considered to be part of (or coincident with) an overall longitudinal pump axis of the scroll pump 100. For example, an “axial distance” between any two components of the scroll pump 100 is a distance measurable along the (extended) drive axis D in either direction (from left to right, or right to left, from the perspective of FIG. 1). The drive axis D / pump axis is horizontal from the perspective of FIG. 1. In addition, terms such as “radial” and “transverse” refer to directions orthogonal to the axis D / pump axis, including the vertical direction from the perspective of FIG. 1. In the present context, the terms “horizontal” and “vertical” are relative to each other. The perspective of FIG. 1 is but one example; that is, the scroll pump 100 is not limited to the orientation shown in FIGS. 1-5. In addition, the scroll pump 100 is considered to have a front side 144 and a rear side 148. From the perspective of FIG. 1, the front side 144 corresponds to the left side and the rear side 148 corresponds to the right side of the scroll pump 100. Along the axial direction, the pump head 102 is nearer to the front side 144 than the motor 104, and the motor 104 is nearer to the rear side 148 than the pump head 102. Further, the pump head 102 is considered to have an outboard side 152 and an inboard side 156. Along the axial direction, the outboard side 152 is nearer to the front side 144 than the inboard side 156, and the inboard side 156 is nearer to the motor 104 than the outboard side 152. Along the axial direction, the outboard side 152 is nearer to the ambient (the space or environment external to the scroll pump 100) than the inboard side 156. In other words, the inboard side 156 is located farther into the interior of the pump head 102 than the outboard side 152. Correspondingly, any of the individual components (e.g., the pumping stage 124) of the pump head 102 likewise may be considered to have an outboard side and an inboard side.

[0032] The scroll pump 100 may further include an outer cowling 164 that covers all or a portion of the pump head 102. The motor 104 may also be enclosed in the cowling 164 or in a motor housing (not shown) distinct from the cowling 164. The cowling 164 and / or motor housing may enclose electrical components external to the motor 104 (e.g., circuitry, wiring / cables, electrical interconnects, other electrical hardware, etc.). An electrical component may be configured to control motor speed, one example being an inverter. The scroll pump 100 may further include a suitable base or platform 168 configured to support the weight of the scroll pump 100 in a stable manner as the scroll pump 100 rests on or is mounted to an underlying surface such as a floor, table, bench, etc.

[0033] The scroll pump 100 may further include one or more cooling fans 172 for directing cooling air into thermal contact with the pump head 102 or additionally the motor 104 to carry dissipated heat away from the scroll pump 100. In the present implementation, a cooling fan 172 is positioned in the pump frame 120 axially between the inboard side of the pumping stage(s) 124 and the motor 104. In this case, the cooling fan 172 may be mounted to and thereby powered by the crankshaft 112 as illustrated. The cooling fan 172 may draw in ambient air from, for example, the rear or outboard side of the pump head 102, such as though one or more openings (vents) formed in the pump frame 120, direct the drawn in ambient air along one or more air flow paths through the interior of the pump frame 120 (including around and in thermal contact with the pumping stage(s) 124), and discharge the now heat-laden ambient air out from one or more openings (vents) formed in the cowling 164 at the front or inboard side of the pump head 102. FIG. 1 depicts an example of a few air flow paths by arrows A.

[0034] FIG. 2 is a cross-sectional elevation view of an example of a pump head 202 according to an implementation of the present disclosure. The pump head 202 may be utilized, for example, as the pump head 102 of the scroll pump 100 described above and illustrated in FIG. 1.

[0035] Generally, the pump head 202 may include a stationary pump frame and / or pump housing (not shown) that encloses and / or supports various components of the pump head 202. For example, various components of the pump head 202 may be integrated with or attached to a pump frame or housing. In the present implementation, the pump head 202 is a multi-stage pump head. Specifically, the pump head 202 is a two-stage pump head and thus includes a first (or outboard, or upstream) pumping stage 224A and a second (or inboard, or downstream) pumping stage 224B fluidly communicating in series (with respect to the fluid flow path F, FIG. 1) with the first pumping stage 224A. The first pumping stage 224A receives the (lower-pressure) working fluid from the pump inlet 128 (FIG. 1), (at least slightly) compresses the working fluid, and outputs the compressed working fluid to the second pumping stage 224B. The second pumping stage 224B further compresses the working fluid and discharges the (now even higher-pressure) working fluid to the pump outlet 136 (FIG. 1). As shown, the total internal volume and volumetric displacement rate of one pumping stage (e.g., first pumping stage 224A) may be different from those of the other pumping stage (e.g., second pumping stage 224B).

[0036] Alternatively, the pump head 202 may be configured such that the inboard pumping stage is the first pumping stage and the outboard pumping stage is the second pumping stage. Alternatively, the pump head 202 may provide more than two pumping stages and / or two or more pumping stages operating in parallel. As another alternative, the pump head 202 may be a single-stage pump head.

[0037] Each pumping stage 224A and 224B provided includes a first scroll and a second scroll nested together in a manner described below. One or both of these scrolls orbits about the drive axis D relative to the other scroll as described further below. In the examples illustrated herein, the first scroll is configured to orbit while the second scroll remains stationary (i.e., as a pump stator). In this case, the first scroll may be referred to as an orbiting scroll and the second scroll may be referred to as a fixed scroll. Alternatively, one or both of the pumping stages 224A and 224B may have a co-rotating configuration in which both scrolls are configured to orbit about the drive axis D relative to each other. In this case, the first scroll may be referred to as a drive scroll and the second scroll may be referred to as a driven scroll, as its orbiting motion is driven by the orbiting motion of the first (drive) scroll.

[0038] In the implementation illustrated in FIG. 2, the pump head 202 includes an orbiting (first) scroll 280 axially interposed between a fixed (second) outboard scroll 284A and a fixed (third) inboard scroll 284B. The fixed outboard scroll 284A and the outboard side of the orbiting scroll 280 cooperatively define the first pumping stage 224A, and the fixed inboard scroll 284B and the inboard side of the orbiting scroll 280 cooperatively define the second pumping stage 224B. During operation of the pump head 202, the orbiting scroll 280 eccentrically orbits in a circular path around the drive axis D at an offset or radial distance r (in the transverse plane orthogonal to the drive axis D) from the drive axis D, as described further below.

[0039] The orbiting scroll 280 includes an orbiting scroll plate 288 oriented in the transverse plane, at least one orbiting outboard (first) scroll blade 292A extending (or projecting) axially from the outboard side of the orbiting scroll plate 288 toward the fixed outboard scroll 284A, and at least one orbiting inboard (second) scroll blade 292B extending (or projecting) axially from the inboard side of the orbiting scroll plate 288 toward the fixed inboard scroll 284B. The fixed outboard scroll 284A includes a transversely-oriented fixed outboard scroll plate 296A and at least one fixed outboard scroll blade 298A extending (or projecting) axially toward the outboard side of the orbiting scroll plate 288. The fixed inboard scroll 284B includes a transversely-oriented fixed inboard scroll plate 296B and at least one fixed inboard scroll blade 298B extending (or projecting) axially toward the inboard side of the orbiting scroll plate 288.

[0040] The fixed inboard scroll 284B may be removably attached to or integral with the above-noted pump frame or housing. The fixed outboard scroll 284A may be removably attached to the fixed inboard scroll 284B (or alternatively to another stationary structure such as the pump frame 210) by an appropriate fastening device (e.g., a pattern of bolts or screws 276 as illustrated, etc.).

[0041] The orbiting outboard scroll blade 292A, the orbiting inboard scroll blade 292B, the fixed outboard scroll blade 298A, and the fixed inboard scroll blade 298B are each spiral-shaped (each runs along a spiral path, which may be Archimedean, involute, etc.) in the transverse plane. The cross-sectional view of FIG. 2 shows several (e.g., four) turns or revolutions taken by the scroll blades 292A, 292B, 298A and 298B, along their respective spiral paths. As shown, the orbiting outboard scroll blade 292A is juxtaposed with the fixed outboard scroll blade 298A in the radial direction (orthogonal to the drive axis D), such that the orbiting outboard scroll blade 292A and the fixed outboard scroll blade 298A are nested (or interleaved, interdigitated, intermeshed, etc.) together with a predetermined relative angular positioning. Likewise, the orbiting inboard scroll blade 292B is juxtaposed with the fixed inboard scroll blade 298B in the radial direction, such that the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B are nested together with a predetermined relative angular positioning. By this configuration, as the orbiting scroll 280 orbits relative to the fixed outboard scroll 284A and the fixed inboard scroll 284B, one or more variable-volume pockets are defined in the first pumping stage 224A by (and between) the nested orbiting outboard scroll blade 292A and fixed outboard scroll blade 298A, and one or more variable-volume pockets are defined in the second pumping stage 224B by (and between) the nested orbiting inboard scroll blade 292B and fixed inboard scroll blade 298B.

[0042] As an example, FIG. 3 is a cross-sectional perspective view of the orbiting scroll 280 in which about half of the orbiting scroll 280 is illustrated. FIG. 3 shows the multi-revolution, spiral shapes of the orbiting outboard scroll blade 292A and orbiting inboard scroll blade 292B. The spiral shapes of the fixed outboard scroll blade 298A and the fixed inboard scroll blade 298B (FIG. 2) may be similar.

[0043] As another example, FIG. 4 is a cross-sectional plan view (in the transverse plane) of the second pumping stage 224B. FIG. 4 illustrates the nested relation between the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B, and the development of crescent-shaped, moving, variable-volume pockets P between adjacent sections of the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B (see also FIG. 5). The second pumping stage 224B includes one or more pumping stage inlet ports located at or near the outer periphery, and one or more pumping stage outlet ports located at or near the center. Generally, the working fluid enters at least one inlet port, is compressed and displaced radially inwardly toward the center, and then is discharged from at least one outlet port. For example, as the orbiting inboard scroll blade 292B orbits, the trailing end of a given (or first) pocket P opens into fluid communication with an inlet port and takes in a quantity of the incoming working fluid. As the orbiting inboard scroll blade 292B continues to orbit, both the leading end and the trailing end of the pocket P may become substantially closed off, i.e., leaving only a small clearance between adjacent points of the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B at the respective leading end and trailing end. In addition, the volume of the pocket P decreases, thereby (at least slightly) compressing the working fluid trapped in the pocket P. As the orbiting inboard scroll blade 292B continues to orbit further, the leading end of the pocket P opens into fluid communication with an outlet port and the compressed working fluid is discharged from the pocket P and through the outlet port. One or more additional pockets P may operate in same manner at least partially simultaneously with the first pocket P.

[0044] In the present implementation, the first pumping stage 224A includes one or more pumping stage inlet ports located at or near the center, and one or more pumping stage outlet ports located at or near the outer periphery. In this configuration, the working fluid enters at least one inlet port, is compressed and displaced radially outwardly toward the outer periphery, and then is discharged from at least one outlet port. This pumping action is effected by moving pockets in a manner analogous to the second pumping stage 224B just described. The working fluid is then transferred to at least one inlet port of the second pumping stage 224B via an interconnecting fluid passage.

[0045] In some implementations, at least one of the pumping stages 224A or 224B includes more than one distinct pair of nested scroll blades. An example of a pumping stage having three pairs of nested scroll blades is described in above-referenced U.S. Pat. No. 5,855,473.

[0046] As shown in FIG. 2, the pump head 202 includes a crankshaft 212, which may correspond to the crankshaft 112 described above and illustrated in FIG. 1. The crankshaft 212 includes a main shaft 206 (portion or section) and an eccentric shaft (portion or section) or crank 210 integral with or attached to the main shaft 206. The main shaft 206 extends in the outboard direction from the motor side (from right to left in FIG. 2) into a central bore 214 of the fixed inboard scroll 284B. The main shaft 206 rotates directly on (coaxial or coincidently with) the drive axis D, which rotation is driven by the motor 104 (FIG. 1). One or more bearings 218 are configured to support the rotation of the main shaft 206 and / or bear thrust forces generated during operation. The crank 210 extends in the outboard direction from the main shaft 206 into the central (orbiting scroll) bore of an orbiting scroll hub 222 of the orbiting scroll 280. The central axis of the crank 210 (designated as crank axis C in FIG. 2A) is radially offset from the central axis of the main shaft 206 (drive axis D) by the above-noted radial distance r and thus orbits in a circular path of radius r around the drive axis D as the main shaft 206 rotates on the drive axis D. The orbiting scroll 280 is coupled to the crank 210 via one or more bearings 226 and thus orbits with the crank 210. The bearings 226 are configured to support the orbiting of the crank 210 and orbiting scroll 280 and / or bear thrust forces generated during operation.

[0047] The pump head 202 is configured to constrain the motion of the orbiting scroll 280 to the orbiting motion only. That is, the pump head 202 is configured to prevent the orbiting scroll 280 from rotating about its own central axis (i.e., the crank axis C). For this purpose, the scroll pump 100 may include an appropriate anti-rotation device (e.g., metal bellows, Oldham coupling, eccentrically positioned synchronization cranks or idler shafts, etc., not shown) interfaced with the orbiting scroll 280 as appreciated by persons skilled in the art.

[0048] In the present implementation, the pump head 202 may further include an axial end cap or cover 274 positioned at the outermost end (on the outboard side) of the crank 210. The end cap 274 may be removably mounted at least partially inside the orbiting scroll hub 222 and secured by an appropriate retainer 278 such as a snap ring, C-clip or the like that expands into an annular inside groove of the orbiting scroll hub 222.

[0049] FIG. 5 is a close-up view of a region of the pumping stages 224A and 224B illustrated in FIG. 2A. As shown, small axial gaps g exist between the blade tips (free ends) of each scroll blade 292A, 292B, 298A and 298B and the surfaces of the scroll plates 288, 296A and 296B that are immediately adjacent to and facing those blade tips. Specifically, an axial gap g exists between the tip of the orbiting outboard scroll blade 292A and the fixed outboard scroll plate 296A, another axial gap g exists between the tip of the fixed outboard scroll blade 298A and the outboard side of the orbiting scroll plate 288, another axial gap g exists between the tip of the orbiting inboard scroll blade 292B and the fixed inboard scroll plate 296B, and an another axial gap g exists between the tip of the fixed inboard scroll blade 298B and the inboard side of the orbiting scroll plate 288. The axial gaps g create partially or substantially fluid-sealed interfaces that allow the development of the above-noted moving, variable-volume pockets P for trapping, compressing and transporting the working fluid without constraining the orbital motion of the orbiting scroll 280.

[0050] In the present implementation, the axial gaps g are at least partially occupied or filled by dynamic tip seals 282. The blade tip of each scroll blade 292A, 292B, 298A and 298B has a groove 286 (see also FIG. 3) in which a tip seal 282 is mounted, such that each groove 286 and corresponding tip seal 282 (orbiting outboard tip seal, orbiting inboard tip seal, fixed outboard tip seal, and fixed inboard tip seal) run along the same spiral path as its corresponding scroll blade 292A, 292B, 298A and 298B. The above-noted axial gap g may be specified as being the axial distance between the bottom of the groove 286 (instead of the blade tip) and the correspondingly adjacent scroll plate 288, 296A and 296B. As one example, the axial gap g may be on the order of a few (e.g., less than 10) thousandths of an inch (e.g., in a range from 0.001″ to 0.002″, or about 0.025 mm to about 0.051 mm). The tip seals 282 may each have a one-piece construction composed of a relatively rigid polymer with low-friction characteristics such as, for example, polytetrafluoroethylene (PTFE), ultra-high-molecular-weight polyethylene (UHMW-PE), etc., or an elastomeric polymer such as, for example, a natural or synthetic rubber (e.g., a closed-cell foam rubber). Alternatively, the tip seals 282 may each have a two-piece construction that includes an elastomeric (springy) layer resting on the bottom of the groove 286 and a wear-resistant layer (e.g., PTFE) disposed on the elastomeric layer and extending out from the groove 286.

[0051] The tip seals 282 may enhance the sealing interfaces between the orbiting scroll 280 and the fixed scrolls 284A and 284B. During operation of the pump head 202 and particularly during the orbital motion of the orbiting scroll 280, the tip seals 282 prevent direct contact between the blade tips of the scroll blades 292A, 292B, 298A and 298B and the correspondingly adjacent scroll plates 288, 296A and 296B. Due to exposure to friction and heat, the tip seals 282 eventually wear down with pump operation over time, which degrades the sealing effectiveness of the tip seals 282 and thus the pumping performance of the pumping stages 224A and 224B (e.g., the ability to generate and maintain vacuum). Thus, the tip seals 282 have a limited service life and periodically need to be replaced as part of a regular maintenance procedure.

[0052] The size (axial distances) of the axial gaps g affects the sealing effectiveness of the tip seals 282 and thus the pumping performance. The axial gap size depends on the axial position of the orbiting scroll 280 relative to the fixed scrolls 284A and 284B.

[0053] In the present implementation, the pump head 202 includes an adjusting nut 290 configured to control (adjust or set) the axial position of the orbiting scroll 280 and hence the axial gap size. The adjusting nut 290 is axially adjustable relative to the crank 210. For this purpose, the adjusting nut 290 may be directly engaged with the crank 210. For example, in the present implementation, the adjusting nut 290 is threaded (screwed) onto the crank 210 such that the adjusting nut 290 is positioned axially between the end cap 274 and the outermost bearing 226 that is at least partially responsible for coupling the crank 210 and the orbiting scroll 280.

[0054] An example of partially disassembling the pump head 202 will now be described with reference being made primarily to FIG. 2. First, any components covering the outboard side of the pump head 202 (e.g., cowling 164 shown in FIG. 1, if provided, and any other covers, caps, etc.) are removed. Next, the fixed outboard scroll 284A is detached (e.g., unfastened) and removed from the fixed inboard scroll 284B (or from another stationary structure of the pump head 202, depending on the implementation). At this time or later, the tip seal 282 of the fixed outboard scroll 284A may be removed and replaced with a new tip seal if needed, and / or the fixed outboard scroll 284A may be otherwise serviced (e.g., cleaned, repaired, relubricated, etc.) or replaced. For example, before mounting a new tip seal, the tip seal groove 286 of the fixed outboard scroll 284A may be cleaned. The end cap 274 is then removed, which may involve removing the retainer 278 (e.g., by utilizing an appropriate tool such as snap-ring pliers). The orbiting scroll 280 is then removed. Depending on the implementation, the outermost bearing 226 may need to be removed before removing the entire orbiting scroll 280. Depending on the implementation, a tool may or may not be needed to assist in removing the outermost bearing 226, or other bearings, or other annular components surrounding the crank 210. At this time or later, the outboard-side and inboard-side tip seals 282 of the orbiting scroll 280 may be removed and replaced with new tip seals if needed, and / or the orbiting scroll 280 may be otherwise serviced (e.g., cleaned, repaired, etc.) or replaced. For example, before mounting a new tip seal, the tip seal grooves 286 of the orbiting scroll 280 may be cleaned. In addition, any components located inside the orbiting scroll hub 222 and / or on or around the crank 210 (e.g., bearings 226, spacers, sleeves, washers, springs, shaft seals, etc.) may be serviced or replaced if needed.

[0055] The removal of the orbiting scroll 280 not only provides access to the inboard-side of the orbiting scroll 280, but also provides access to the fixed inboard scroll 284B from the outboard side of the pump head 202. The removal of the orbiting scroll 280 exposes the fixed inboard scroll 284B to the outboard side of the pump head 202. Hence, access to the fixed inboard scroll 284B does not require the fixed inboard scroll 284B to be detached and removed from the pump frame or housing, and such access also does not require the fixed inboard scroll 284B or any other any other component on the inboard side of the pump head 202 to be detached and / or removed from the crankshaft 212, shaft coupling 116 (FIG. 1), motor shaft 108, motor 104, or the like. With the orbiting scroll 280 removed, the tip seal 282 of the fixed inboard scroll 284B is then removed and replaced with a new tip seal, and the tip seal groove 286 of the fixed inboard scroll 284B may be cleaned, if needed. After maintenance is completed, reassembly of the pump head 202 may entail essentially the reverse of the foregoing steps of disassembly.

[0056] As an example, a scroll pump such as disclosed herein may operate at a pumping speed in a range from 30 L / min to 1200 L / min. As an example, a scroll pump such as disclosed herein may operate at an inlet pressure in a range from 1 atmosphere (735.6 Torr) to 1×10−4 Torr. As an example, a scroll pump such as disclosed herein may generate an ultimate vacuum level in a range from 2 Torr to 5×104 Torr.

[0057] FIG. 6 is a schematic view of an example of a vacuum pumping system 600 according to an implementation of the present disclosure. The vacuum pumping system 600 includes a scroll pump 100 with a pump inlet 128, a pump outlet 136, a pump head 102 or 202, and a motor 104 such as described above and illustrated in FIGS. 1-5. In the present implementation, the pump inlet 128 is in fluid communication with a vacuum chamber 604. Generally, the vacuum chamber 604 may be any chamber (or enclosed space) to be evacuated by operation of the scroll pump 100. The vacuum chamber 604 may be a part of any apparatus 608 (or device, instrument, system, etc.) that requires the pressure of an internal volume or region to be pumped down to and maintained at a predetermined vacuum level. Examples of the apparatus 608 include, but are not limited to, a gas leak detector, mass spectrometer, ion mobility spectrometer, electron microscope, etc.

[0058] Alternatively, the scroll pump 100 may be a compressor. In this case, the pump outlet 136 may be placed in fluid communication with a downstream destination, as described above.

[0059] The vacuum pumping system 600 may include an inlet pressure sensor 612 positioned in operative communication with the inlet line of the scroll pump 100 upstream of the pumping stage(s) of the pump head 102 / 202, at or near the pump inlet 128, for measuring (or monitoring) the inlet pressure of the scroll pump 100 during operation thereof. The vacuum pumping system 600 may also include an outlet pressure sensor 616 positioned in operative communication with the outlet line of the scroll pump 100 downstream of the pumping stage(s) of the pump head 102 / 202, at or near the pump outlet 136, for measuring (or monitoring) the outlet pressure of the scroll pump 100 during operation thereof. Measurement of the inlet pressure or additionally the outlet pressure may be done on a continuous basis or intermittently (e.g., at predetermined time intervals). The scroll pump 100 is configured to operate at different inlet pressures, or in different ranges of inlet pressure (or different inlet pressure regimes, or additionally different outlet pressure regimes), depending on the implementation. In some implementations, the scroll pump 100 may be considered as including the inlet pressure sensor 612 and the outlet pressure sensor 616.

[0060] The inlet pressure sensor 612 measures pump inlet pressure directly. Alternatively or additionally, the scroll pump 100 may include one or more sensors configured to measure an operating parameter from which the pump inlet pressure can be calculated or derived. Examples include, but are not limited to, an electrical current sensor 614 and a voltage sensor 618, one or both of which may be provided as part of the drive circuitry of the motor 104. At a given motor speed, there is a known relationship between the current drawn by the motor 104 and the pump inlet pressure. At a given motor speed, there is also a known relationship between the power drawn by the motor 104 and the pump inlet pressure. Thus, the pump inlet pressure may be calculated from the measurement signals outputted from the current sensor 614 and / or voltage sensor 618 to the controller 632 described below.

[0061] The vacuum pumping system 600 also includes a run time meter 620 configured to measure (or log) the cumulative time of operation of the scroll pump 100. For example, the run time meter 620 may be positioned in operative communication with the motor 104 and log the amount of time the motor 104 is operating. The vacuum pumping system 600 may also include a pump speed sensor 624 (e.g., an encoder, tachometer, etc.) configured to measure (or monitor) the rotational speed (e.g., in revolutions per minute, RPM) of the scroll pump 100, for example, through operative communication with a rotating component such as the orbiting scroll 280 (FIG. 2), the motor shaft 108 or the crankshaft 112 (FIG. 1). In some implementations, the pump speed sensor 624 may serve as a run time meter, in which case the separate run time meter 620 may not be needed or, alternatively, the operations of both the run time meter 620 and the pump speed sensor 624 may be coordinated to properly log the run time (time of operation) of the scroll pump 100. The run time meter 620 and / or the pump speed sensor 624 may be integrated with the motor controller or other electronics provided at the motor 104. The vacuum pumping system 600 may also include one or more temperature sensors 628 located at one or more positions in the scroll pump 100 to measure (or monitor) temperature at one or more regions of the scroll pump 100.

[0062] The vacuum pumping system 600 further includes a system controller (or controller, or computing device) 632. The controller 632 may schematically represent one or more modules (or units, components, etc.) configured (or programmed) for controlling, monitoring and / or timing various functional aspects of the vacuum pumping system 600 including, for example, the operations of components of (or communicating with) the scroll pump 100. For all such purposes, the controller 632 may be in wired or wireless communication with one or more of the components of the vacuum pumping system 600, as depicted by dashed lines in FIG. 6, and may include any suitable combination of hardware, firmware, software, etc., including one or more electronics-based processors and memories, as appreciated by persons skilled in the art. For example, the controller 632 may include a non-transitory (or tangible) computer-readable medium that includes non-transitory instructions for performing any of the methods disclosed herein. All or part of the controller 632, as well as the run time meter 1020 and / or the pump speed sensor 1024, may be located directly at the scroll pump 500, such as in an electronics box or as part of an inverter drive that supplies power to the motor 504. A more detailed example of the controller 632 is described below with reference to FIG. 7.

[0063] As one example, the controller 632 may control the pump speed, and thus pump inlet and outlet pressures, by sending control signals to the motor 104 (or motor electronics) to control the motor 104 and thus the speed of the drive shaft (e.g., the motor shaft 108 and crankshaft illustrated in FIG. 1). In an implementation, the controller 632 operates the scroll pump 100 at different, predetermined pressure ranges as noted above, according to the specific application to which the scroll pump 100 is utilized. In an implementation, the controller 632 cooperates with the inlet pressure sensor 612 (or additionally the outlet pressure sensor 616) and the run time meter 620 (and / or the pump speed sensor 624) to log accumulated run time for each predetermined pressure range at which the scroll pump 100 has been operating. Alternatively or additionally, the controller 632 utilizes measurements made by the current sensor 614 and / or voltage sensor 618 to calculate inlet pressure values, as described above. In this way, the controller 632 acquires data relating to different amounts of accumulated run time (run time durations) of the scroll pump 100 for each respective pressure range. The controller 632 may then use the acquired run time data to determine that the tip seal(s) 282 (FIGS. 2 and 5) have become too worn for further operation. Stated in another way, the controller 632 may use the acquired run time data to predict the point in time when the tip seal(s) 282 have become worn to the degree that the tip seal(s) 282 should be replaced with new tip seal(s) 282 to maintain an acceptable level of pump performance. The controller 632 may be configured (or programmed) to make this determination intermittently (e.g., at predetermined intervals of time) or continuously during operation of the scroll pump 100.

[0064] In an implementation, an expected (tip seal) service life may be associated with each pressure range in which the scroll pump 100 is operated. The expected service life is a time duration predetermined for each pressure range. During the expected service life, the degree of wear of a tip seal 282 is considered to be low enough that it does not impair pump operation to an unacceptable degree. The end of the expected service life may generally mark the time at which the tip seal wear has advanced to a degree warranting replacement of the tip seal 282. For this implementation, the pressure range is considered to be the primary factor influencing the expected service life. Operation at a higher pressure range will result in a shorter expected service life, whereas operation at a lower pressure range (relative to the higher pressure range) will result in a longer expected service life (relative to the shorter expected service life corresponding to operation at the higher pressure range). For each pressure range, the corresponding expected service life may be determined empirically (e.g., from experimental or historical data). For example, the expected service life may be based on data acquired from prior operations (runs) of the scroll pump 100. Besides inlet pressure, other factors may be utilized to determine the expected service life as deemed appropriate such as, for example, measurements of outlet pressure, operating temperature (e.g., of the pump head 102 / 202), etc.

[0065] Thus, in an implementation, the controller 632 may be configured to make the determination that the orbiting scroll tip seal(s) 282 and / or the fixed scroll tip seal(s) 282 is / are worn tip seal(s) based on the following acquired data: the duration of each run time measured (e.g., by the run time meter 620); and the respective durations of several different expected service lives of the scroll tip seals 282, wherein each expected service life corresponds to a respective one of the pressure ranges (and corresponding run time interval) as described above.

[0066] If the controller 632 positively determines that the orbiting scroll tip seal(s) 282 and / or the fixed scroll tip seal(s) 282 is / are worn tip seal(s) such that they should be replaced, the controller 632 may then produce an output of any appropriate type to the user such as, for example, an audible alarm, a visual alarm, a wired or wireless communication (e.g., email, text message, etc.), etc., or a combination of two or more different types of alarms or communications, as appreciated by persons skilled in the art.

[0067] In an implementation, the controller 632 may be configured to determine that the first scroll tip seal (e.g., the orbiting scroll tip seal(s) 282, or drive scroll tip seal in the case of co-rotating scrolls described above) and / or second scroll tip seal (e.g., the fixed scroll tip seal(s) 282, or drive scroll tip seal in the case of co-rotating scrolls described above) is / are worn tip seal(s) based (at least in part) on an assessment of “cumulative tip seal wear” (or “cumulative wear”). A current (recently calculated) value of cumulative tip seal wear is determined. Then, the current value of cumulative tip seal wear is compared to a predetermined threshold value of cumulative tip seal wear to determine whether the current value equals or exceeds the threshold value. A positive determination of excessive cumulative tip seal wear indicates that the tip seal(s) should be replaced. The threshold value may be determined empirically or by any other appropriate means.

[0068] As an example, the scroll pump 100 may be operated in N different pressure ranges, where Nis any integer number greater than 2. In this case, there are N corresponding run times (the lengths of time the scroll pump 100 was operated in the respective pressure ranges) and N corresponding expected service lives. The controller 632 may be configured to determine that the orbiting scroll tip seal(s) 282 and / or the fixed scroll tip seal(s) 282 is / are worn tip seal(s) based (at least in part) on the following calculation of (equation for) cumulative tip seal wear, CW:CW=Trun⁢1Tesl⁢1+Trun⁢2Tesl⁢2+…+Trun⁢NTesl⁢N

[0069] where Trun1 is the duration of the first run time of operation in the first pressure range, Tesl1 is the duration of the first expected service life when operating in the first pressure range, Trun2 is the duration of the second run time of operation in the second pressure range (different from the first pressure range), Tesl2 is the duration of the second expected service life when operating in the second pressure range, TrunN is the duration of the Nth run time of operation in the Nth pressure range (different from the first and second pressure ranges, and any additional pressure ranges between the second pressure range and the Nth pressure range), and TeslN is the duration of the Nth amount of expected service life when operating in the Nth pressure range. The dimension for all of these values is time, for example, hours or other units as deemed appropriate for the particular application.

[0070] The calculated CW value is then compared to a predetermined threshold CW value as described above to determine whether the threshold CW value has been reached and thereby determine whether the scroll tip seal(s) 282 have become worn to the degree that they should be replaced (changed out with new scroll tip seal(s) 282). In an implementation, a threshold CW value of 1.0 is considered to correspond to the end of service life of one or more scroll tip seal(s) 282 currently installed in the scroll pump 100. However, any value less than 1.0 (e.g., 0.8) may be utilized as the threshold value for CW, for example, to ensure that the worn tip seal(s) 282 is / are changed out before appreciably impairing the performance of the scroll pump 100.

[0071] In an implementation, for a scroll pump 100 that operates primarily in, for example, two pressure ranges R1 (corresponding to Trun1 / Tesl1) and R2 (corresponding to Trun2 / Tesl2), these two pressure ranges R1 and R2 may be further divided into narrower subranges (e.g., R1a, R1b, . . . . R1n; and R2a, R2b, . . . . R2n), and expected service lives (e.g., Tesl1a, Tesl1b, . . . , Tesl1n; and Tesl2a, Tesl2b, . . . , Tesl2n) may be determined for these subranges appropriately. The above calculation / equation for cumulative wear, CW, may then be utilized in the same way as just described.

[0072] As a more specific example, assume that the scroll pump 100 is operated in two pressure ranges: a first pressure range, R1, below 10 Torr (e.g., between 3 Torr and 10 Torr), and a second pressure range, R2, above 10 Torr (e.g., between 10 Torr and 50 Torr). Assume further that the first expected service life, Tesl1, has been determined (or estimated) to be 10,000 hours and the second expected service life, Tesl2, has been determined (or estimated) to be 3000 hours. In this case, cumulative tip seal wear would be determined (or calculated) according to the above equation (with N=0) as follows:CW=Trun⁢110,000+Trun⁢23000

[0073] The controller 632 may then compare the calculated CW value with the predetermined threshold value to determine whether it is time to replace the tip seal(s) 282. If so, the controller 632 may produce one or more alerts and / or otherwise communicate with the user in the manner described above. The user may then shut down the scroll pump 100, at least partially disassemble the pump head 102 / 202, remove the fixed outboard 284A and orbiting scroll 280, replace the tip seal(s) 282, and service or replace other components as needed and as described above.

[0074] In the context of the present disclosure, the term “wear” is generally taken to mean loss of volume (removal) of a tip seal 282 over time due to sliding contact (e.g., rubbing) between the tip seal 282 and the opposing surface (e.g., the orbiting scroll plate 288, fixed outboard scroll plate 296A, or fixed inboard scroll plate 296B described above and illustrated in FIGS. 2-5). As such, the condition of “wear” is to be distinguished from failure modes that are a concern in other technological fields such as, for example, fatigue (e.g., evolution of microcracks), plastic deformation, stress, strain, pitting, breaking, degradation due to chemical reaction or incident electromagnetic radiation, etc.

[0075] FIG. 7 is a schematic view of an example of a system controller 700 configured to control a vacuum pumping system (e.g., 600), in particular the scroll pump 100 and its sensing / measuring / logging devices, according to an implementation of the present disclosure. All or part of the controller 700 may correspond to the controller 632 described above in conjunction with FIG. 6. The controller 700 may schematically represent one or more modules, control units, components, or the like configured for controlling, monitoring, analyzing and / or timing the operations of various devices or components of the vacuum pumping system 600, as well as controlling or executing one or more steps of any of the methods disclosed herein. In addition to the various controllable devices or components described above in conjunction with FIG. 6, other devices may include, but are not limited to, electrical power (voltage) sources, timing controllers, clocks, frequency / waveform generators, processors, logic circuits, memories, databases, etc. One or more modules of the controller 700 may be, or be embodied in, one or more devices located outside or separate from the vacuum pumping system 600, for example, a computer workstation, desktop computer, laptop computer, portable computer, tablet computer, handheld computer, mobile computing device, personal digital assistant (PDA), smartphone, etc. One or more modules of the controller 700 may communicate with one or more other modules via one or more busses or other types of communication lines or wireless links, as appreciated by persons skilled in the art.

[0076] In the illustrated implementation, the controller 700 includes one or more electronics-based processors 702, which may be representative of a main electronic processor providing overall control, and one or more electronic processors configured for dedicated control operations or specific signal processing tasks (e.g., a graphics processing unit or GPU, a digital signal processor or DSP, an application-specific integrated circuit or ASIC, a field-programmable gate array or FPGA, etc.). The controller 700 also includes one or more memories 704 (volatile and / or non-volatile types, e.g., RAM and / or ROM) for storing data and / or software. Stored data may be organized, for example, in one or more databases or look-up tables. The controller 700 may also include one or more device drivers 706 for controlling one or more types of user interface devices and providing an interface between the user interface devices and components of the controller 700 communicating with the user interface devices. Such user interface devices may include user input devices 708 (e.g., keyboard, keypad, touch screen, mouse, joystick, trackball, and the like) and user output devices 710 (e.g., display screen, printer, visual indicators or alerts, audible indicators or alerts, and the like). In various implementations, the controller 700 may be considered as including one or more of the user input devices 708 and / or user output devices 710, or at least as communicating with them.

[0077] In some implementations, the controller 700 may also include one or more types of computer programs or software contained in memory and / or on one or more types of non-transitory (or tangible) computer-readable media. One or more devices of the controller 700 may be configured to receive and read (and optionally write to) the computer-readable media. The computer programs or software may contain non-transitory instructions (e.g., logic instructions) for controlling or performing various operations of the vacuum pumping system 600, such as the operations of the various devices described herein. The computer programs or software may include system software and application software. System software may include an operating system (e.g., a Microsoft Windows® operating system) for controlling and managing various functions of the controller 700, including interaction between hardware and application software. In particular, the operating system may provide a graphical user interface (GUI) displayable via a user output device 710, and with which a user may interact with the use of a user input device 708. Application software may include software configured to control or execute various operations of the vacuum pumping system 600, and / or some or all of the steps of any of the methods disclosed herein.

[0078] The controller 700 may also include a motor controller (or control module) 712 configured to control the operation of the motor 104 (e.g., on / off states, power supplied, drive shaft speed, etc.) and thus the rotational velocity of the orbiting scroll 280 and inlet and outlet pressures of the pump head 102 / 202 (FIGS. 1, 2 and 6). The controller 700 may also include one or more sensor interfaces 714 configured to receive and process feedback (e.g., measurement) signals received from one or more sensors / meters / data loggers provided with the vacuum pumping system 600, such as the inlet pressure sensor 614, outlet pressure sensor 616, current sensor 614, voltage sensor 618, run time meter 620, speed sensor 624, and temperature sensor 628 described above (FIG. 6). For example, the sensor interfaces 714 may be embodied in different pieces of firmware or other electronic circuitry that are part of a microcontroller of the controller 700. The sensor interfaces 714 may communicate with the motor controller 712 and other components of the controller 700 as needed to provide effective control of various operations of the vacuum pumping system 600 and the performing of any of the methods described herein. The firmware or other electronic circuitry embodying the motor controller 712 also may be provided with the same microcontroller that includes the sensor interfaces 714, or may be provided with separate hardware of the controller 700. The controller 700 may also include a data acquisition module (or DAQ) 716 configured to further condition or process the signals received by the sensor interface(s) 714 as needed for preparing data to be analyzed by the controller 700. The controller 700 may also include a wear analyzer (or analyzing module) configured to analyze the data and make the determinations in accordance with any of the methods described herein.

[0079] FIG. 8 is a flow diagram 800 illustrating an example of a method for predicting tip seal wear in a scroll pump according to an implementation of the present disclosure. The method may utilize the various hardware components, modules and structures described herein. The method starts with providing a scroll pump such as described herein (step 802). Accordingly, the scroll pump may include a pump inlet, a pump outlet, and a pumping stage. The pumping stage may include a first scroll and at least one (inboard or outboard) second scroll nested together. The first scroll and / or the second scroll is / are configured to orbit about a drive axis relative to the other of the first scroll and second scroll to create a moving pocket between the orbiting scroll and the fixed scroll effective to pump fluid from the pump inlet to the pump outlet. The first scroll includes at least one first scroll tip seal, and the second scroll includes at least one second scroll tip seal.

[0080] The scroll pump is operated, such as to evacuate (or “pump down”) a vacuum chamber such as described above. Specifically, the scroll pump is operated for a plurality of run times in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges (step 804). The durations of the successive run times are measured (step 806) (e.g., the accumulative hours of operation during each pressure regime are counted or logged). In addition, the pump inlet pressure during the operating of the scroll pump for each of the run times is determined by direct measurement of pressure (using a pressure gauge), or by calculation based on operating parameters having a correlation with pressure (e.g., current and / or voltage), as described above (step 808). A determination is then made (e.g., by the controller 632 / 700 described herein) as to whether at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal (step 810). The determining step 810 is based on: the duration of each run time measured; and respective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges. If the determination is positive—that is, if it is determined that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal—the scroll pump is shut down and the worn tip seal(s) is / are replaced in the manner described herein.

[0081] In an implementation, one or more steps of the method just described and illustrated in FIG. 8 may be controlled or performed by a controller including a processor, memory, and other components as appreciated by persons skilled in the art, such as the controller 632 / 700 described above in conjunction with FIGS. 6 and 7.

[0082] In an implementation, the flow diagram 800 may represent a scroll pump, or additionally a vacuum pumping system, configured to carry out the steps shown in the flow diagram 800. For this purpose, various components of the scroll pump 100 and / or vacuum pumping system 600 described and illustrated herein may be utilized.

[0083] It will be understood that one or more of the processes, sub-processes, and process steps described herein may be performed by hardware, firmware, software, or a combination of two or more of the foregoing, on one or more electronic or digitally-controlled devices. The software may reside in a software memory (not shown) in a suitable electronic processing component or system such as, for example, the system controller 632 or 700 schematically depicted in FIG. 6 or 7. The software memory may include an ordered listing of executable instructions for implementing logical functions (that is, “logic” that may be implemented in digital form such as digital circuitry or source code, or in analog form such as an analog source such as an analog electrical, sound, or video signal). The instructions may be executed within a processing module, which includes, for example, one or more microprocessors, general purpose processors, combinations of processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate array (FPGAs), etc. Further, the schematic diagrams describe a logical division of functions having physical (hardware and / or software) implementations that are not limited by architecture or the physical layout of the functions. The examples of systems described herein may be implemented in a variety of configurations and operate as hardware / software components in a single hardware / software unit, or in separate hardware / software units.

[0084] The executable instructions may be implemented as a computer program product having instructions stored therein which, when executed by a processing module of an electronic system (e.g., the system controller 632 or 700 schematically depicted in FIG. 6 or 7), direct the electronic system to carry out the instructions. The computer program product may be selectively embodied in any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as an electronic computer-based system, processor-containing system, or other system that may selectively fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this disclosure, a computer-readable storage medium is any non-transitory means that may store the program for use by or in connection with the instruction execution system, apparatus, or device. The non-transitory computer-readable storage medium may selectively be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device. A non-exhaustive list of more specific examples of non-transitory computer readable media include: an electrical connection having one or more wires (electronic); a portable computer diskette (magnetic); a random access memory (electronic); a read-only memory (electronic); an erasable programmable read only memory such as, for example, flash memory (electronic); a compact disc memory such as, for example, CD-ROM, CD-R, CD-RW (optical); and digital versatile disc memory, i.e., DVD (optical). Note that the non-transitory computer-readable storage medium may even be paper or another suitable medium upon which the program is printed, as the program may be electronically captured via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner if necessary, and then stored in a computer memory or machine memory.

[0085] It will also be understood that the term “in signal communication” or “in electrical communication” as used herein means that two or more systems, devices, components, modules, or sub-modules are capable of communicating with each other via signals that travel over some type of signal path. The signals may be communication, power, data, or energy signals, which may communicate information, power, or energy from a first system, device, component, module, or sub-module to a second system, device, component, module, or sub-module along a signal path between the first and second system, device, component, module, or sub-module. The signal paths may include physical, electrical, magnetic, electromagnetic, electrochemical, optical, wired, or wireless connections. The signal paths may also include additional systems, devices, components, modules, or sub-modules between the first and second system, device, component, module, or sub-module.

[0086] More generally, terms such as “communicate” and “in . . . communication with” (for example, a first component “communicates with” or “is in communication with” a second component) are used herein to indicate a structural, functional, mechanical, electrical, signal, optical, magnetic, electromagnetic, ionic or fluidic relationship between two or more components or elements. As such, the fact that one component is said to communicate with a second component is not intended to exclude the possibility that additional components may be present between, and / or operatively associated or engaged with, the first and second components.

[0087] It will be understood that various aspects or details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation—the invention being defined by the claims.

Examples

Embodiment Construction

[0025]In this disclosure, all “implementations,”“aspects,”“examples,” and “embodiments” described are considered to be non-limiting and non-exclusive. Accordingly, the fact that a specific “implementation,”“aspect,”“example,” or “embodiment” is explicitly described herein does not exclude other “implementations,”“aspects,”“examples,” and “embodiments” from the scope of the present disclosure even if not explicitly described. In this disclosure, the terms “implementations,”“aspect,”“example,” and “embodiment” are used interchangeably, i.e., are considered to have interchangeable meanings.

[0026]In this disclosure, the term “substantially,”“approximately,” or “about,” when modifying a specified numerical value, may be taken to encompass a range of values that include + / −10% of such numerical value, unless specifically indicated otherwise.

[0027]FIG. 1 is a cross-sectional elevation view of an example of a scroll pump (assembly) 100 in which the subject matter disclosed herein may be imp...

TECHNICAL FIELD

[0001] The present invention relates to scroll pumps, particularly to maintenance or servicing of scroll pumps, and more particularly to replacement of tip seals of scroll pumps.BACKGROUND

[0002] Scroll pumps are widely utilized as compressors for supplying a pressurized working fluid (e.g., compressed air, refrigerant, etc.) and as vacuum pumps for evacuating a chamber by removing a working fluid from the chamber. As appreciated by the skilled artisan, a scroll pump has at least one pumping (or compression) stage formed by an orbiting scroll and a fixed (stationary) scroll. The orbiting scroll has an orbiting scroll blade extending in an axial direction from a radially oriented orbiting scroll plate (or base) toward the fixed scroll. The fixed scroll has a fixed scroll blade extending in the opposite axial direction from a radially oriented fixed scroll plate (or base) toward the orbiting scroll. The scroll blades (or “wraps”) are spiral-shaped. That is, each scroll blade runs along a spiral path in multiple revolutions around the central region of its corresponding scroll plate. The orbiting and fixed scroll blades are nested with each other. The scroll pump further has a motor-driven crankshaft that rotates about its central shaft axis, or drive axis. The crankshaft has an eccentrically positioned crank located at the end of the crankshaft that is opposite to the motor. The central axis of the crank is radially offset from the drive axis of the main part of the crankshaft. Thus, as the main part of the crankshaft rotates about the drive axis, the crank orbits in a circle (whose radius corresponds to the radial offset distance) around the drive axis. The orbiting scroll is coupled to the crank and thus orbits with the crank, but without the orbiting scroll itself rotating on its own axis.

[0003] In operation, the orbiting scroll is driven by the crankshaft to orbit around the drive axis relative to the fixed scroll to create one or more moving, variable-volume pumping chambers or zones, also referred to as “pockets”, between the orbiting scroll blade and the fixed scroll blade. Each pocket is defined between and bounded by adjacent sections of the orbiting scroll blade and the fixed scroll blade. As the orbiting scroll orbits, the pockets receive the (gas-phase or liquid-phase) working fluid from a pump inlet and displace (transport or convey) the working fluid to a pump outlet. As the pockets move in accordance with the orbiting motion, the volume of the space inside the pockets decreases, thereby compressing the working fluid to some degree as the working fluid is being displaced toward the pump outlet.

[0004] An example of the structure and operation of such a scroll pump is described in U.S. Pat. No. 5,855,473, the entire contents of which are incorporated by reference herein.

[0005] A scroll pump may have more than one pumping stage, such as two pumping stages fluidly connected in series. For example, the orbiting scroll may be positioned between two fixed scrolls, namely, a fixed outboard scroll having a fixed outboard scroll blade and a fixed inboard scroll having a fixed inboard scroll blade. In this case, the orbiting scroll has one orbiting scroll blade on its inboard side and another orbiting scroll blade on its outboard side. The orbiting outboard scroll blade is nested with the fixed outboard scroll blade to cooperatively define one (outboard) pumping stage, and the orbiting inboard scroll blade is nested with the fixed inboard scroll blade to cooperatively define another (inboard) pumping stage, In operation, the first pumping stage (either the outboard stage or the inboard stage, depending on configuration) receives the working fluid from the pump inlet, compresses the working fluid, and transfers the compressed working fluid to the second pumping stage. The second pumping stage further compresses the working fluid and discharges the further compressed working fluid toward the pump outlet. An example of such a two-stage scroll pump is described in above-referenced U.S. Pat. No. 5,855,473.

[0006] In either a single-stage or multi-stage scroll pump, the orbiting scroll and the fixed scroll(s) may not contact each other. Instead, small axial gaps exist between the blade tips (free ends) of each scroll blade and the surfaces of the scroll plates that are immediately axially adjacent to and facing those corresponding blade tips. For example, on a given (outboard or inboard) side of the orbiting scroll plate, the blade tip of the orbiting scroll blade is spaced from the surface of the fixed scroll plate by an axial gap. Likewise, on the same side, the blade tip of the fixed scroll blade is spaced from the surface of the orbiting scroll plate by an axial gap. The axial gaps are necessary so that the orbiting scroll may move with respect to the fixed scroll(s). The scroll pump may be a “dry” scroll pump, meaning that it is not sealed or lubricated by a liquid such as oil. In this case, the axial gaps are closed and sealed by tip seals mounted to the respective blade tips, such that each tip seal runs continuously along the same spiral path as its corresponding scroll blade. The tip seals enhance the sealing interfaces between the orbiting scroll and the fixed scroll(s) without impairing the motion of the orbiting scroll.

[0007] In an alternative configuration, a scroll pump may be configured as a co-rotating scroll pump. In this case, for a given pumping stage, both scrolls orbit relative to each other. The scroll directly powered by the drive shaft may be termed the drive scroll and the other scroll may be termed the driven scroll. An example of a co-rotating scroll pump is described in U.S. Pat. No. 5,256,042, the entire contents of which are incorporated by reference herein.

[0008] In all types of dry scroll pumps utilizing tip seals, the tip seals wear down with pump operation over time due to sliding contact (e.g., rubbing) between the tip seals and the opposing, adjacent surfaces of the corresponding scroll plates (with the sliding contact occurring at least intermittently). Hence, the tip seals eventually and periodically need to be replaced with new tip seals, which requires at least partially disassembling the pump head to gain access to the tip seals. It would be desirable to know when a tip seal should be changed at a point in time before the tip seal wears to a point where the scroll pump starts to lose its vacuum performance. In certain applications, it can be very costly and undesirable to have an unplanned shutdown due to the need to replace a worn tip seal.

[0009] In view of the foregoing, there is a need for solutions regarding the replacement of tip seals in scroll pumps.SUMMARY

[0010] To address the foregoing problems, in whole or in part, and / or other problems that may have been observed by persons skilled in the art, the present disclosure provides methods, processes, systems, apparatus, instruments, and / or devices, as described by way of example in implementations set forth below.

[0011] According to one implementation, a method for replacing a tip seal in a scroll pump (e.g., a scroll pump assembly, or at least a scroll pump head thereof) includes: providing a scroll pump comprising a pump inlet, a pump outlet, and a pumping stage, wherein the pumping stage comprises a first scroll and a second scroll nested together, at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to pump fluid from the pump inlet to the pump outlet, the first scroll comprises a first scroll tip seal, and the second scroll comprises a second scroll tip seal; operating the scroll pump for a plurality of run times in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges; measuring a duration of each run time; determining the pump inlet pressure during the operating of the scroll pump for each of the amounts of run time; and determining that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal. The determination is based on: the duration of each run time measured; and respective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges.

[0012] According to another implementation, a scroll pump (e.g., a scroll pump assembly, or at least a scroll pump head thereof) includes: a pump inlet; a pump outlet; a pumping stage comprising a first scroll and a second scroll nested together, at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to pump fluid from the pump inlet to the pump outlet; a first scroll tip seal mounted to the first scroll; a second scroll tip seal mounted to the second scroll; a sensor configured to measure pump inlet pressure or to measure an operating parameter from which the pump inlet pressure can be calculated; a runtime meter configured to measure a plurality of run times during which the scroll pump operates in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges; and a controller configured to determine that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal. The determination is based on: the duration of each run time measured; and respective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges.

[0013] According to another implementation, a non-transitory computer-readable medium includes instructions stored thereon, that when executed on a processor, control or perform one or more of the steps of any of the methods disclosed herein.

[0014] Other devices, apparatus, systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention can be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.

[0016] FIG. 1 is a cross-sectional elevation view of an example of a scroll pump (assembly) in which the subject matter disclosed herein may be implemented.

[0017] FIG. 2 is a cross-sectional elevation view of an example of a pump head for a scroll pump according to an implementation of the present disclosure.

[0018] FIG. 3 is a cross-sectional perspective view of an orbiting scroll included with the pump head illustrated in FIG. 2.

[0019] FIG. 4 is a cross-sectional plan view (in the transverse plane) of a pumping stage of the pump head illustrated in FIG. 2.

[0020] FIG. 5 is a close-up view of a region of two pumping stages of the pump head illustrated in FIG. 2.

[0021] FIG. 6 is a schematic view of an example of a vacuum pumping system according to an implementation of the present disclosure.

[0022] FIG. 7 is a schematic view of a system controller for a vacuum pumping system according to an implementation of the present disclosure.

[0023] FIG. 8 is a flow diagram illustrating an example of a method for replacing a tip seal in a scroll pump according to an implementation of the present disclosure.

[0024] The illustrations in all of the drawing figures are considered to be schematic, unless specifically indicated otherwise.DETAILED DESCRIPTION

[0025] In this disclosure, all “implementations,”“aspects,”“examples,” and “embodiments” described are considered to be non-limiting and non-exclusive. Accordingly, the fact that a specific “implementation,”“aspect,”“example,” or “embodiment” is explicitly described herein does not exclude other “implementations,”“aspects,”“examples,” and “embodiments” from the scope of the present disclosure even if not explicitly described. In this disclosure, the terms “implementations,”“aspect,”“example,” and “embodiment” are used interchangeably, i.e., are considered to have interchangeable meanings.

[0026] In this disclosure, the term “substantially,”“approximately,” or “about,” when modifying a specified numerical value, may be taken to encompass a range of values that include + / −10% of such numerical value, unless specifically indicated otherwise.

[0027] FIG. 1 is a cross-sectional elevation view of an example of a scroll pump (assembly) 100 in which the subject matter disclosed herein may be implemented. The scroll pump 100 may be configured for use as a vacuum pump or as a compressor, as appreciated by persons skilled in the art. The type of working fluid pumped by the scroll pump 100 depends on the application for which the scroll pump 100 is utilized. The working fluid is often a gas (or mixture of gases) such as, for example, air, oxygen, nitrogen, a noble gas (e.g., helium, argon, etc.), a gas-phase compound (e.g., carbon dioxide, a refrigerant, etc.), a gas utilized in a chemical, manufacturing, or analytical process, or in applications requiring compressed air, etc. Alternatively, the working fluid may be a liquid such as may be utilized in a chemical, manufacturing, or analytical process, or a refrigerant in cooling applications, etc. The structure and operation of scroll pumps are generally understood by persons skilled in the art, and thus the scroll pump 100 and certain components thereof are described only briefly herein to provide a context for the presently disclosed subject matter.

[0028] The scroll pump 100 includes a pump head 102 powered by a motor 104. Typically, the motor 104 is an electric motor that includes a motor rotor (not shown) driven to rotate relative to a motor stator (not shown) by a magnetic field established between the motor rotor and motor stator by permanent magnets and / or electromagnets provided with the motor rotor and motor stator, as appreciated by persons skilled in the art. The motor rotor is coupled to a motor (output) shaft 108 that thus rotates with the motor rotor. The motor shaft 108 is coupled to a crankshaft 112 by an appropriate shaft coupling 116 such that the crankshaft 112 is driven to rotate by the motor rotor via the motor shaft 108 and shaft coupling 116. The shaft coupling 116 may be a mechanical coupling (e.g., shaft joint, spider coupling, etc.) or a non-contact type of coupling such as an axially- or radially-oriented magnetic coupling, as appreciated by persons skilled in the art. Alternatively, the pump head 102 and motor 104 are directly coupled by a single drive shaft instead of utilizing a separate motor shaft 108, crankshaft 112 and intermediate shaft coupling 116. The motor shaft 108 and at least a main portion of the crankshaft 112 rotate concentrically or coincidently about a central drive axis D.

[0029] The pump head 102 includes a pump frame 120, which may be a single-part construction or a multi-part construction in which two or more separate frame parts may be assembled to each other and disassembled from each other (e.g., for performing maintenance on the scroll pump 100). The pump frame 120 may be configured to serve as a pump housing that encloses various components of the pump head 102, and / or as a structural support to which various components are attached or with which various components are integral. The pump head 102 further includes one or more pumping elements configured to define one or more pumping (or compression) stages 124. At least one of the pumping elements is coupled to and driven to move by the crankshaft 112. In the implementations described herein, the pumping elements are scrolls as described in more detail below. The pump head 102 further includes a pump inlet 128 and an inlet conduit 132 (e.g., one or more passages, pipes, tubes, chambers, manifolds, plenums, headers, etc.) configured to direct a flow of incoming (aspirated) working fluid (the fluid being pumped) from the pump inlet 128 to the pumping stage(s) 124. The pump head 102 further includes a pump outlet 136 and an outlet conduit 140 (e.g., one or more passages, pipes, tubes, chambers, manifolds, plenums, headers, etc.) configured to direct a flow of outgoing (discharged) working fluid from the pumping stage(s) 124 to the pump outlet 136. Accordingly, the pump head 102 (particularly the pumping stage(s) 124) is configured to transport (or displace by pumping action) the working fluid from the pump inlet 128, through the inlet conduit 132, through the pumping stage(s) 124 and through the outlet conduit 140, and to the pump outlet 136, as indicated by an arrow F in FIG. 1. The inlet side of the pumping stage(s) 124 is the low-pressure (or vacuum) side and the outlet side of the pumping stage(s) 124 is the high-pressure side (the term “high” being relative to the term “low”).

[0030] The pump inlet 128 and / or the pump outlet 136 may include fittings as needed for fluidly connecting the pump head 102 to components (e.g., conduits, chambers, etc.) external to the scroll pump 100. For example, in the case of a vacuum pump, the pump inlet 128 may be configured to be fluidly coupled to a vacuum chamber (i.e., a chamber or enclosed space to be evacuated; see FIG. 6) and, depending on the application, the pump outlet 136 may discharge compressed fluid directly to the ambient or may be configured to be fluidly coupled to an appropriate receptacle for containing the discharged fluid. In the case of a compressor, the pump inlet 128 may be configured to be fluidly coupled to an upstream part of a system that circulates the working fluid (e.g., a heat exchanger or refrigeration system) or to intake ambient air (e.g., in the case of an air compressor), and the pump outlet 136 may be configured to be fluidly coupled to a device, tool or system that utilizes compressed fluid (i.e., is a consumer of compressed fluid, such as an air-powered tool). Such a downstream entity that receives compressed fluid from the scroll pump 100 may be referred to generally as a “destination” fluidly communicating with the pump outlet 136.

[0031] For purposes of reference and description, terms such as “axial” and “axially” are taken relative to the drive axis D. The drive axis D may be extended in either direction and considered to be part of (or coincident with) an overall longitudinal pump axis of the scroll pump 100. For example, an “axial distance” between any two components of the scroll pump 100 is a distance measurable along the (extended) drive axis D in either direction (from left to right, or right to left, from the perspective of FIG. 1). The drive axis D / pump axis is horizontal from the perspective of FIG. 1. In addition, terms such as “radial” and “transverse” refer to directions orthogonal to the axis D / pump axis, including the vertical direction from the perspective of FIG. 1. In the present context, the terms “horizontal” and “vertical” are relative to each other. The perspective of FIG. 1 is but one example; that is, the scroll pump 100 is not limited to the orientation shown in FIGS. 1-5. In addition, the scroll pump 100 is considered to have a front side 144 and a rear side 148. From the perspective of FIG. 1, the front side 144 corresponds to the left side and the rear side 148 corresponds to the right side of the scroll pump 100. Along the axial direction, the pump head 102 is nearer to the front side 144 than the motor 104, and the motor 104 is nearer to the rear side 148 than the pump head 102. Further, the pump head 102 is considered to have an outboard side 152 and an inboard side 156. Along the axial direction, the outboard side 152 is nearer to the front side 144 than the inboard side 156, and the inboard side 156 is nearer to the motor 104 than the outboard side 152. Along the axial direction, the outboard side 152 is nearer to the ambient (the space or environment external to the scroll pump 100) than the inboard side 156. In other words, the inboard side 156 is located farther into the interior of the pump head 102 than the outboard side 152. Correspondingly, any of the individual components (e.g., the pumping stage 124) of the pump head 102 likewise may be considered to have an outboard side and an inboard side.

[0032] The scroll pump 100 may further include an outer cowling 164 that covers all or a portion of the pump head 102. The motor 104 may also be enclosed in the cowling 164 or in a motor housing (not shown) distinct from the cowling 164. The cowling 164 and / or motor housing may enclose electrical components external to the motor 104 (e.g., circuitry, wiring / cables, electrical interconnects, other electrical hardware, etc.). An electrical component may be configured to control motor speed, one example being an inverter. The scroll pump 100 may further include a suitable base or platform 168 configured to support the weight of the scroll pump 100 in a stable manner as the scroll pump 100 rests on or is mounted to an underlying surface such as a floor, table, bench, etc.

[0033] The scroll pump 100 may further include one or more cooling fans 172 for directing cooling air into thermal contact with the pump head 102 or additionally the motor 104 to carry dissipated heat away from the scroll pump 100. In the present implementation, a cooling fan 172 is positioned in the pump frame 120 axially between the inboard side of the pumping stage(s) 124 and the motor 104. In this case, the cooling fan 172 may be mounted to and thereby powered by the crankshaft 112 as illustrated. The cooling fan 172 may draw in ambient air from, for example, the rear or outboard side of the pump head 102, such as though one or more openings (vents) formed in the pump frame 120, direct the drawn in ambient air along one or more air flow paths through the interior of the pump frame 120 (including around and in thermal contact with the pumping stage(s) 124), and discharge the now heat-laden ambient air out from one or more openings (vents) formed in the cowling 164 at the front or inboard side of the pump head 102. FIG. 1 depicts an example of a few air flow paths by arrows A.

[0034] FIG. 2 is a cross-sectional elevation view of an example of a pump head 202 according to an implementation of the present disclosure. The pump head 202 may be utilized, for example, as the pump head 102 of the scroll pump 100 described above and illustrated in FIG. 1.

[0035] Generally, the pump head 202 may include a stationary pump frame and / or pump housing (not shown) that encloses and / or supports various components of the pump head 202. For example, various components of the pump head 202 may be integrated with or attached to a pump frame or housing. In the present implementation, the pump head 202 is a multi-stage pump head. Specifically, the pump head 202 is a two-stage pump head and thus includes a first (or outboard, or upstream) pumping stage 224A and a second (or inboard, or downstream) pumping stage 224B fluidly communicating in series (with respect to the fluid flow path F, FIG. 1) with the first pumping stage 224A. The first pumping stage 224A receives the (lower-pressure) working fluid from the pump inlet 128 (FIG. 1), (at least slightly) compresses the working fluid, and outputs the compressed working fluid to the second pumping stage 224B. The second pumping stage 224B further compresses the working fluid and discharges the (now even higher-pressure) working fluid to the pump outlet 136 (FIG. 1). As shown, the total internal volume and volumetric displacement rate of one pumping stage (e.g., first pumping stage 224A) may be different from those of the other pumping stage (e.g., second pumping stage 224B).

[0036] Alternatively, the pump head 202 may be configured such that the inboard pumping stage is the first pumping stage and the outboard pumping stage is the second pumping stage. Alternatively, the pump head 202 may provide more than two pumping stages and / or two or more pumping stages operating in parallel. As another alternative, the pump head 202 may be a single-stage pump head.

[0037] Each pumping stage 224A and 224B provided includes a first scroll and a second scroll nested together in a manner described below. One or both of these scrolls orbits about the drive axis D relative to the other scroll as described further below. In the examples illustrated herein, the first scroll is configured to orbit while the second scroll remains stationary (i.e., as a pump stator). In this case, the first scroll may be referred to as an orbiting scroll and the second scroll may be referred to as a fixed scroll. Alternatively, one or both of the pumping stages 224A and 224B may have a co-rotating configuration in which both scrolls are configured to orbit about the drive axis D relative to each other. In this case, the first scroll may be referred to as a drive scroll and the second scroll may be referred to as a driven scroll, as its orbiting motion is driven by the orbiting motion of the first (drive) scroll.

[0038] In the implementation illustrated in FIG. 2, the pump head 202 includes an orbiting (first) scroll 280 axially interposed between a fixed (second) outboard scroll 284A and a fixed (third) inboard scroll 284B. The fixed outboard scroll 284A and the outboard side of the orbiting scroll 280 cooperatively define the first pumping stage 224A, and the fixed inboard scroll 284B and the inboard side of the orbiting scroll 280 cooperatively define the second pumping stage 224B. During operation of the pump head 202, the orbiting scroll 280 eccentrically orbits in a circular path around the drive axis D at an offset or radial distance r (in the transverse plane orthogonal to the drive axis D) from the drive axis D, as described further below.

[0039] The orbiting scroll 280 includes an orbiting scroll plate 288 oriented in the transverse plane, at least one orbiting outboard (first) scroll blade 292A extending (or projecting) axially from the outboard side of the orbiting scroll plate 288 toward the fixed outboard scroll 284A, and at least one orbiting inboard (second) scroll blade 292B extending (or projecting) axially from the inboard side of the orbiting scroll plate 288 toward the fixed inboard scroll 284B. The fixed outboard scroll 284A includes a transversely-oriented fixed outboard scroll plate 296A and at least one fixed outboard scroll blade 298A extending (or projecting) axially toward the outboard side of the orbiting scroll plate 288. The fixed inboard scroll 284B includes a transversely-oriented fixed inboard scroll plate 296B and at least one fixed inboard scroll blade 298B extending (or projecting) axially toward the inboard side of the orbiting scroll plate 288.

[0040] The fixed inboard scroll 284B may be removably attached to or integral with the above-noted pump frame or housing. The fixed outboard scroll 284A may be removably attached to the fixed inboard scroll 284B (or alternatively to another stationary structure such as the pump frame 210) by an appropriate fastening device (e.g., a pattern of bolts or screws 276 as illustrated, etc.).

[0041] The orbiting outboard scroll blade 292A, the orbiting inboard scroll blade 292B, the fixed outboard scroll blade 298A, and the fixed inboard scroll blade 298B are each spiral-shaped (each runs along a spiral path, which may be Archimedean, involute, etc.) in the transverse plane. The cross-sectional view of FIG. 2 shows several (e.g., four) turns or revolutions taken by the scroll blades 292A, 292B, 298A and 298B, along their respective spiral paths. As shown, the orbiting outboard scroll blade 292A is juxtaposed with the fixed outboard scroll blade 298A in the radial direction (orthogonal to the drive axis D), such that the orbiting outboard scroll blade 292A and the fixed outboard scroll blade 298A are nested (or interleaved, interdigitated, intermeshed, etc.) together with a predetermined relative angular positioning. Likewise, the orbiting inboard scroll blade 292B is juxtaposed with the fixed inboard scroll blade 298B in the radial direction, such that the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B are nested together with a predetermined relative angular positioning. By this configuration, as the orbiting scroll 280 orbits relative to the fixed outboard scroll 284A and the fixed inboard scroll 284B, one or more variable-volume pockets are defined in the first pumping stage 224A by (and between) the nested orbiting outboard scroll blade 292A and fixed outboard scroll blade 298A, and one or more variable-volume pockets are defined in the second pumping stage 224B by (and between) the nested orbiting inboard scroll blade 292B and fixed inboard scroll blade 298B.

[0042] As an example, FIG. 3 is a cross-sectional perspective view of the orbiting scroll 280 in which about half of the orbiting scroll 280 is illustrated. FIG. 3 shows the multi-revolution, spiral shapes of the orbiting outboard scroll blade 292A and orbiting inboard scroll blade 292B. The spiral shapes of the fixed outboard scroll blade 298A and the fixed inboard scroll blade 298B (FIG. 2) may be similar.

[0043] As another example, FIG. 4 is a cross-sectional plan view (in the transverse plane) of the second pumping stage 224B. FIG. 4 illustrates the nested relation between the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B, and the development of crescent-shaped, moving, variable-volume pockets P between adjacent sections of the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B (see also FIG. 5). The second pumping stage 224B includes one or more pumping stage inlet ports located at or near the outer periphery, and one or more pumping stage outlet ports located at or near the center. Generally, the working fluid enters at least one inlet port, is compressed and displaced radially inwardly toward the center, and then is discharged from at least one outlet port. For example, as the orbiting inboard scroll blade 292B orbits, the trailing end of a given (or first) pocket P opens into fluid communication with an inlet port and takes in a quantity of the incoming working fluid. As the orbiting inboard scroll blade 292B continues to orbit, both the leading end and the trailing end of the pocket P may become substantially closed off, i.e., leaving only a small clearance between adjacent points of the orbiting inboard scroll blade 292B and the fixed inboard scroll blade 298B at the respective leading end and trailing end. In addition, the volume of the pocket P decreases, thereby (at least slightly) compressing the working fluid trapped in the pocket P. As the orbiting inboard scroll blade 292B continues to orbit further, the leading end of the pocket P opens into fluid communication with an outlet port and the compressed working fluid is discharged from the pocket P and through the outlet port. One or more additional pockets P may operate in same manner at least partially simultaneously with the first pocket P.

[0044] In the present implementation, the first pumping stage 224A includes one or more pumping stage inlet ports located at or near the center, and one or more pumping stage outlet ports located at or near the outer periphery. In this configuration, the working fluid enters at least one inlet port, is compressed and displaced radially outwardly toward the outer periphery, and then is discharged from at least one outlet port. This pumping action is effected by moving pockets in a manner analogous to the second pumping stage 224B just described. The working fluid is then transferred to at least one inlet port of the second pumping stage 224B via an interconnecting fluid passage.

[0045] In some implementations, at least one of the pumping stages 224A or 224B includes more than one distinct pair of nested scroll blades. An example of a pumping stage having three pairs of nested scroll blades is described in above-referenced U.S. Pat. No. 5,855,473.

[0046] As shown in FIG. 2, the pump head 202 includes a crankshaft 212, which may correspond to the crankshaft 112 described above and illustrated in FIG. 1. The crankshaft 212 includes a main shaft 206 (portion or section) and an eccentric shaft (portion or section) or crank 210 integral with or attached to the main shaft 206. The main shaft 206 extends in the outboard direction from the motor side (from right to left in FIG. 2) into a central bore 214 of the fixed inboard scroll 284B. The main shaft 206 rotates directly on (coaxial or coincidently with) the drive axis D, which rotation is driven by the motor 104 (FIG. 1). One or more bearings 218 are configured to support the rotation of the main shaft 206 and / or bear thrust forces generated during operation. The crank 210 extends in the outboard direction from the main shaft 206 into the central (orbiting scroll) bore of an orbiting scroll hub 222 of the orbiting scroll 280. The central axis of the crank 210 (designated as crank axis C in FIG. 2A) is radially offset from the central axis of the main shaft 206 (drive axis D) by the above-noted radial distance r and thus orbits in a circular path of radius r around the drive axis D as the main shaft 206 rotates on the drive axis D. The orbiting scroll 280 is coupled to the crank 210 via one or more bearings 226 and thus orbits with the crank 210. The bearings 226 are configured to support the orbiting of the crank 210 and orbiting scroll 280 and / or bear thrust forces generated during operation.

[0047] The pump head 202 is configured to constrain the motion of the orbiting scroll 280 to the orbiting motion only. That is, the pump head 202 is configured to prevent the orbiting scroll 280 from rotating about its own central axis (i.e., the crank axis C). For this purpose, the scroll pump 100 may include an appropriate anti-rotation device (e.g., metal bellows, Oldham coupling, eccentrically positioned synchronization cranks or idler shafts, etc., not shown) interfaced with the orbiting scroll 280 as appreciated by persons skilled in the art.

[0048] In the present implementation, the pump head 202 may further include an axial end cap or cover 274 positioned at the outermost end (on the outboard side) of the crank 210. The end cap 274 may be removably mounted at least partially inside the orbiting scroll hub 222 and secured by an appropriate retainer 278 such as a snap ring, C-clip or the like that expands into an annular inside groove of the orbiting scroll hub 222.

[0049] FIG. 5 is a close-up view of a region of the pumping stages 224A and 224B illustrated in FIG. 2A. As shown, small axial gaps g exist between the blade tips (free ends) of each scroll blade 292A, 292B, 298A and 298B and the surfaces of the scroll plates 288, 296A and 296B that are immediately adjacent to and facing those blade tips. Specifically, an axial gap g exists between the tip of the orbiting outboard scroll blade 292A and the fixed outboard scroll plate 296A, another axial gap g exists between the tip of the fixed outboard scroll blade 298A and the outboard side of the orbiting scroll plate 288, another axial gap g exists between the tip of the orbiting inboard scroll blade 292B and the fixed inboard scroll plate 296B, and an another axial gap g exists between the tip of the fixed inboard scroll blade 298B and the inboard side of the orbiting scroll plate 288. The axial gaps g create partially or substantially fluid-sealed interfaces that allow the development of the above-noted moving, variable-volume pockets P for trapping, compressing and transporting the working fluid without constraining the orbital motion of the orbiting scroll 280.

[0050] In the present implementation, the axial gaps g are at least partially occupied or filled by dynamic tip seals 282. The blade tip of each scroll blade 292A, 292B, 298A and 298B has a groove 286 (see also FIG. 3) in which a tip seal 282 is mounted, such that each groove 286 and corresponding tip seal 282 (orbiting outboard tip seal, orbiting inboard tip seal, fixed outboard tip seal, and fixed inboard tip seal) run along the same spiral path as its corresponding scroll blade 292A, 292B, 298A and 298B. The above-noted axial gap g may be specified as being the axial distance between the bottom of the groove 286 (instead of the blade tip) and the correspondingly adjacent scroll plate 288, 296A and 296B. As one example, the axial gap g may be on the order of a few (e.g., less than 10) thousandths of an inch (e.g., in a range from 0.001″ to 0.002″, or about 0.025 mm to about 0.051 mm). The tip seals 282 may each have a one-piece construction composed of a relatively rigid polymer with low-friction characteristics such as, for example, polytetrafluoroethylene (PTFE), ultra-high-molecular-weight polyethylene (UHMW-PE), etc., or an elastomeric polymer such as, for example, a natural or synthetic rubber (e.g., a closed-cell foam rubber). Alternatively, the tip seals 282 may each have a two-piece construction that includes an elastomeric (springy) layer resting on the bottom of the groove 286 and a wear-resistant layer (e.g., PTFE) disposed on the elastomeric layer and extending out from the groove 286.

[0051] The tip seals 282 may enhance the sealing interfaces between the orbiting scroll 280 and the fixed scrolls 284A and 284B. During operation of the pump head 202 and particularly during the orbital motion of the orbiting scroll 280, the tip seals 282 prevent direct contact between the blade tips of the scroll blades 292A, 292B, 298A and 298B and the correspondingly adjacent scroll plates 288, 296A and 296B. Due to exposure to friction and heat, the tip seals 282 eventually wear down with pump operation over time, which degrades the sealing effectiveness of the tip seals 282 and thus the pumping performance of the pumping stages 224A and 224B (e.g., the ability to generate and maintain vacuum). Thus, the tip seals 282 have a limited service life and periodically need to be replaced as part of a regular maintenance procedure.

[0052] The size (axial distances) of the axial gaps g affects the sealing effectiveness of the tip seals 282 and thus the pumping performance. The axial gap size depends on the axial position of the orbiting scroll 280 relative to the fixed scrolls 284A and 284B.

[0053] In the present implementation, the pump head 202 includes an adjusting nut 290 configured to control (adjust or set) the axial position of the orbiting scroll 280 and hence the axial gap size. The adjusting nut 290 is axially adjustable relative to the crank 210. For this purpose, the adjusting nut 290 may be directly engaged with the crank 210. For example, in the present implementation, the adjusting nut 290 is threaded (screwed) onto the crank 210 such that the adjusting nut 290 is positioned axially between the end cap 274 and the outermost bearing 226 that is at least partially responsible for coupling the crank 210 and the orbiting scroll 280.

[0054] An example of partially disassembling the pump head 202 will now be described with reference being made primarily to FIG. 2. First, any components covering the outboard side of the pump head 202 (e.g., cowling 164 shown in FIG. 1, if provided, and any other covers, caps, etc.) are removed. Next, the fixed outboard scroll 284A is detached (e.g., unfastened) and removed from the fixed inboard scroll 284B (or from another stationary structure of the pump head 202, depending on the implementation). At this time or later, the tip seal 282 of the fixed outboard scroll 284A may be removed and replaced with a new tip seal if needed, and / or the fixed outboard scroll 284A may be otherwise serviced (e.g., cleaned, repaired, relubricated, etc.) or replaced. For example, before mounting a new tip seal, the tip seal groove 286 of the fixed outboard scroll 284A may be cleaned. The end cap 274 is then removed, which may involve removing the retainer 278 (e.g., by utilizing an appropriate tool such as snap-ring pliers). The orbiting scroll 280 is then removed. Depending on the implementation, the outermost bearing 226 may need to be removed before removing the entire orbiting scroll 280. Depending on the implementation, a tool may or may not be needed to assist in removing the outermost bearing 226, or other bearings, or other annular components surrounding the crank 210. At this time or later, the outboard-side and inboard-side tip seals 282 of the orbiting scroll 280 may be removed and replaced with new tip seals if needed, and / or the orbiting scroll 280 may be otherwise serviced (e.g., cleaned, repaired, etc.) or replaced. For example, before mounting a new tip seal, the tip seal grooves 286 of the orbiting scroll 280 may be cleaned. In addition, any components located inside the orbiting scroll hub 222 and / or on or around the crank 210 (e.g., bearings 226, spacers, sleeves, washers, springs, shaft seals, etc.) may be serviced or replaced if needed.

[0055] The removal of the orbiting scroll 280 not only provides access to the inboard-side of the orbiting scroll 280, but also provides access to the fixed inboard scroll 284B from the outboard side of the pump head 202. The removal of the orbiting scroll 280 exposes the fixed inboard scroll 284B to the outboard side of the pump head 202. Hence, access to the fixed inboard scroll 284B does not require the fixed inboard scroll 284B to be detached and removed from the pump frame or housing, and such access also does not require the fixed inboard scroll 284B or any other any other component on the inboard side of the pump head 202 to be detached and / or removed from the crankshaft 212, shaft coupling 116 (FIG. 1), motor shaft 108, motor 104, or the like. With the orbiting scroll 280 removed, the tip seal 282 of the fixed inboard scroll 284B is then removed and replaced with a new tip seal, and the tip seal groove 286 of the fixed inboard scroll 284B may be cleaned, if needed. After maintenance is completed, reassembly of the pump head 202 may entail essentially the reverse of the foregoing steps of disassembly.

[0056] As an example, a scroll pump such as disclosed herein may operate at a pumping speed in a range from 30 L / min to 1200 L / min. As an example, a scroll pump such as disclosed herein may operate at an inlet pressure in a range from 1 atmosphere (735.6 Torr) to 1×10−4 Torr. As an example, a scroll pump such as disclosed herein may generate an ultimate vacuum level in a range from 2 Torr to 5×104 Torr.

[0057] FIG. 6 is a schematic view of an example of a vacuum pumping system 600 according to an implementation of the present disclosure. The vacuum pumping system 600 includes a scroll pump 100 with a pump inlet 128, a pump outlet 136, a pump head 102 or 202, and a motor 104 such as described above and illustrated in FIGS. 1-5. In the present implementation, the pump inlet 128 is in fluid communication with a vacuum chamber 604. Generally, the vacuum chamber 604 may be any chamber (or enclosed space) to be evacuated by operation of the scroll pump 100. The vacuum chamber 604 may be a part of any apparatus 608 (or device, instrument, system, etc.) that requires the pressure of an internal volume or region to be pumped down to and maintained at a predetermined vacuum level. Examples of the apparatus 608 include, but are not limited to, a gas leak detector, mass spectrometer, ion mobility spectrometer, electron microscope, etc.

[0058] Alternatively, the scroll pump 100 may be a compressor. In this case, the pump outlet 136 may be placed in fluid communication with a downstream destination, as described above.

[0059] The vacuum pumping system 600 may include an inlet pressure sensor 612 positioned in operative communication with the inlet line of the scroll pump 100 upstream of the pumping stage(s) of the pump head 102 / 202, at or near the pump inlet 128, for measuring (or monitoring) the inlet pressure of the scroll pump 100 during operation thereof. The vacuum pumping system 600 may also include an outlet pressure sensor 616 positioned in operative communication with the outlet line of the scroll pump 100 downstream of the pumping stage(s) of the pump head 102 / 202, at or near the pump outlet 136, for measuring (or monitoring) the outlet pressure of the scroll pump 100 during operation thereof. Measurement of the inlet pressure or additionally the outlet pressure may be done on a continuous basis or intermittently (e.g., at predetermined time intervals). The scroll pump 100 is configured to operate at different inlet pressures, or in different ranges of inlet pressure (or different inlet pressure regimes, or additionally different outlet pressure regimes), depending on the implementation. In some implementations, the scroll pump 100 may be considered as including the inlet pressure sensor 612 and the outlet pressure sensor 616.

[0060] The inlet pressure sensor 612 measures pump inlet pressure directly. Alternatively or additionally, the scroll pump 100 may include one or more sensors configured to measure an operating parameter from which the pump inlet pressure can be calculated or derived. Examples include, but are not limited to, an electrical current sensor 614 and a voltage sensor 618, one or both of which may be provided as part of the drive circuitry of the motor 104. At a given motor speed, there is a known relationship between the current drawn by the motor 104 and the pump inlet pressure. At a given motor speed, there is also a known relationship between the power drawn by the motor 104 and the pump inlet pressure. Thus, the pump inlet pressure may be calculated from the measurement signals outputted from the current sensor 614 and / or voltage sensor 618 to the controller 632 described below.

[0061] The vacuum pumping system 600 also includes a run time meter 620 configured to measure (or log) the cumulative time of operation of the scroll pump 100. For example, the run time meter 620 may be positioned in operative communication with the motor 104 and log the amount of time the motor 104 is operating. The vacuum pumping system 600 may also include a pump speed sensor 624 (e.g., an encoder, tachometer, etc.) configured to measure (or monitor) the rotational speed (e.g., in revolutions per minute, RPM) of the scroll pump 100, for example, through operative communication with a rotating component such as the orbiting scroll 280 (FIG. 2), the motor shaft 108 or the crankshaft 112 (FIG. 1). In some implementations, the pump speed sensor 624 may serve as a run time meter, in which case the separate run time meter 620 may not be needed or, alternatively, the operations of both the run time meter 620 and the pump speed sensor 624 may be coordinated to properly log the run time (time of operation) of the scroll pump 100. The run time meter 620 and / or the pump speed sensor 624 may be integrated with the motor controller or other electronics provided at the motor 104. The vacuum pumping system 600 may also include one or more temperature sensors 628 located at one or more positions in the scroll pump 100 to measure (or monitor) temperature at one or more regions of the scroll pump 100.

[0062] The vacuum pumping system 600 further includes a system controller (or controller, or computing device) 632. The controller 632 may schematically represent one or more modules (or units, components, etc.) configured (or programmed) for controlling, monitoring and / or timing various functional aspects of the vacuum pumping system 600 including, for example, the operations of components of (or communicating with) the scroll pump 100. For all such purposes, the controller 632 may be in wired or wireless communication with one or more of the components of the vacuum pumping system 600, as depicted by dashed lines in FIG. 6, and may include any suitable combination of hardware, firmware, software, etc., including one or more electronics-based processors and memories, as appreciated by persons skilled in the art. For example, the controller 632 may include a non-transitory (or tangible) computer-readable medium that includes non-transitory instructions for performing any of the methods disclosed herein. All or part of the controller 632, as well as the run time meter 1020 and / or the pump speed sensor 1024, may be located directly at the scroll pump 500, such as in an electronics box or as part of an inverter drive that supplies power to the motor 504. A more detailed example of the controller 632 is described below with reference to FIG. 7.

[0063] As one example, the controller 632 may control the pump speed, and thus pump inlet and outlet pressures, by sending control signals to the motor 104 (or motor electronics) to control the motor 104 and thus the speed of the drive shaft (e.g., the motor shaft 108 and crankshaft illustrated in FIG. 1). In an implementation, the controller 632 operates the scroll pump 100 at different, predetermined pressure ranges as noted above, according to the specific application to which the scroll pump 100 is utilized. In an implementation, the controller 632 cooperates with the inlet pressure sensor 612 (or additionally the outlet pressure sensor 616) and the run time meter 620 (and / or the pump speed sensor 624) to log accumulated run time for each predetermined pressure range at which the scroll pump 100 has been operating. Alternatively or additionally, the controller 632 utilizes measurements made by the current sensor 614 and / or voltage sensor 618 to calculate inlet pressure values, as described above. In this way, the controller 632 acquires data relating to different amounts of accumulated run time (run time durations) of the scroll pump 100 for each respective pressure range. The controller 632 may then use the acquired run time data to determine that the tip seal(s) 282 (FIGS. 2 and 5) have become too worn for further operation. Stated in another way, the controller 632 may use the acquired run time data to predict the point in time when the tip seal(s) 282 have become worn to the degree that the tip seal(s) 282 should be replaced with new tip seal(s) 282 to maintain an acceptable level of pump performance. The controller 632 may be configured (or programmed) to make this determination intermittently (e.g., at predetermined intervals of time) or continuously during operation of the scroll pump 100.

[0064] In an implementation, an expected (tip seal) service life may be associated with each pressure range in which the scroll pump 100 is operated. The expected service life is a time duration predetermined for each pressure range. During the expected service life, the degree of wear of a tip seal 282 is considered to be low enough that it does not impair pump operation to an unacceptable degree. The end of the expected service life may generally mark the time at which the tip seal wear has advanced to a degree warranting replacement of the tip seal 282. For this implementation, the pressure range is considered to be the primary factor influencing the expected service life. Operation at a higher pressure range will result in a shorter expected service life, whereas operation at a lower pressure range (relative to the higher pressure range) will result in a longer expected service life (relative to the shorter expected service life corresponding to operation at the higher pressure range). For each pressure range, the corresponding expected service life may be determined empirically (e.g., from experimental or historical data). For example, the expected service life may be based on data acquired from prior operations (runs) of the scroll pump 100. Besides inlet pressure, other factors may be utilized to determine the expected service life as deemed appropriate such as, for example, measurements of outlet pressure, operating temperature (e.g., of the pump head 102 / 202), etc.

[0065] Thus, in an implementation, the controller 632 may be configured to make the determination that the orbiting scroll tip seal(s) 282 and / or the fixed scroll tip seal(s) 282 is / are worn tip seal(s) based on the following acquired data: the duration of each run time measured (e.g., by the run time meter 620); and the respective durations of several different expected service lives of the scroll tip seals 282, wherein each expected service life corresponds to a respective one of the pressure ranges (and corresponding run time interval) as described above.

[0066] If the controller 632 positively determines that the orbiting scroll tip seal(s) 282 and / or the fixed scroll tip seal(s) 282 is / are worn tip seal(s) such that they should be replaced, the controller 632 may then produce an output of any appropriate type to the user such as, for example, an audible alarm, a visual alarm, a wired or wireless communication (e.g., email, text message, etc.), etc., or a combination of two or more different types of alarms or communications, as appreciated by persons skilled in the art.

[0067] In an implementation, the controller 632 may be configured to determine that the first scroll tip seal (e.g., the orbiting scroll tip seal(s) 282, or drive scroll tip seal in the case of co-rotating scrolls described above) and / or second scroll tip seal (e.g., the fixed scroll tip seal(s) 282, or drive scroll tip seal in the case of co-rotating scrolls described above) is / are worn tip seal(s) based (at least in part) on an assessment of “cumulative tip seal wear” (or “cumulative wear”). A current (recently calculated) value of cumulative tip seal wear is determined. Then, the current value of cumulative tip seal wear is compared to a predetermined threshold value of cumulative tip seal wear to determine whether the current value equals or exceeds the threshold value. A positive determination of excessive cumulative tip seal wear indicates that the tip seal(s) should be replaced. The threshold value may be determined empirically or by any other appropriate means.

[0068] As an example, the scroll pump 100 may be operated in N different pressure ranges, where Nis any integer number greater than 2. In this case, there are N corresponding run times (the lengths of time the scroll pump 100 was operated in the respective pressure ranges) and N corresponding expected service lives. The controller 632 may be configured to determine that the orbiting scroll tip seal(s) 282 and / or the fixed scroll tip seal(s) 282 is / are worn tip seal(s) based (at least in part) on the following calculation of (equation for) cumulative tip seal wear, CW:CW=Trun⁢1Tesl⁢1+Trun⁢2Tesl⁢2+…+Trun⁢NTesl⁢N

[0069] where Trun1 is the duration of the first run time of operation in the first pressure range, Tesl1 is the duration of the first expected service life when operating in the first pressure range, Trun2 is the duration of the second run time of operation in the second pressure range (different from the first pressure range), Tesl2 is the duration of the second expected service life when operating in the second pressure range, TrunN is the duration of the Nth run time of operation in the Nth pressure range (different from the first and second pressure ranges, and any additional pressure ranges between the second pressure range and the Nth pressure range), and TeslN is the duration of the Nth amount of expected service life when operating in the Nth pressure range. The dimension for all of these values is time, for example, hours or other units as deemed appropriate for the particular application.

[0070] The calculated CW value is then compared to a predetermined threshold CW value as described above to determine whether the threshold CW value has been reached and thereby determine whether the scroll tip seal(s) 282 have become worn to the degree that they should be replaced (changed out with new scroll tip seal(s) 282). In an implementation, a threshold CW value of 1.0 is considered to correspond to the end of service life of one or more scroll tip seal(s) 282 currently installed in the scroll pump 100. However, any value less than 1.0 (e.g., 0.8) may be utilized as the threshold value for CW, for example, to ensure that the worn tip seal(s) 282 is / are changed out before appreciably impairing the performance of the scroll pump 100.

[0071] In an implementation, for a scroll pump 100 that operates primarily in, for example, two pressure ranges R1 (corresponding to Trun1 / Tesl1) and R2 (corresponding to Trun2 / Tesl2), these two pressure ranges R1 and R2 may be further divided into narrower subranges (e.g., R1a, R1b, . . . . R1n; and R2a, R2b, . . . . R2n), and expected service lives (e.g., Tesl1a, Tesl1b, . . . , Tesl1n; and Tesl2a, Tesl2b, . . . , Tesl2n) may be determined for these subranges appropriately. The above calculation / equation for cumulative wear, CW, may then be utilized in the same way as just described.

[0072] As a more specific example, assume that the scroll pump 100 is operated in two pressure ranges: a first pressure range, R1, below 10 Torr (e.g., between 3 Torr and 10 Torr), and a second pressure range, R2, above 10 Torr (e.g., between 10 Torr and 50 Torr). Assume further that the first expected service life, Tesl1, has been determined (or estimated) to be 10,000 hours and the second expected service life, Tesl2, has been determined (or estimated) to be 3000 hours. In this case, cumulative tip seal wear would be determined (or calculated) according to the above equation (with N=0) as follows:CW=Trun⁢110,000+Trun⁢23000

[0073] The controller 632 may then compare the calculated CW value with the predetermined threshold value to determine whether it is time to replace the tip seal(s) 282. If so, the controller 632 may produce one or more alerts and / or otherwise communicate with the user in the manner described above. The user may then shut down the scroll pump 100, at least partially disassemble the pump head 102 / 202, remove the fixed outboard 284A and orbiting scroll 280, replace the tip seal(s) 282, and service or replace other components as needed and as described above.

[0074] In the context of the present disclosure, the term “wear” is generally taken to mean loss of volume (removal) of a tip seal 282 over time due to sliding contact (e.g., rubbing) between the tip seal 282 and the opposing surface (e.g., the orbiting scroll plate 288, fixed outboard scroll plate 296A, or fixed inboard scroll plate 296B described above and illustrated in FIGS. 2-5). As such, the condition of “wear” is to be distinguished from failure modes that are a concern in other technological fields such as, for example, fatigue (e.g., evolution of microcracks), plastic deformation, stress, strain, pitting, breaking, degradation due to chemical reaction or incident electromagnetic radiation, etc.

[0075] FIG. 7 is a schematic view of an example of a system controller 700 configured to control a vacuum pumping system (e.g., 600), in particular the scroll pump 100 and its sensing / measuring / logging devices, according to an implementation of the present disclosure. All or part of the controller 700 may correspond to the controller 632 described above in conjunction with FIG. 6. The controller 700 may schematically represent one or more modules, control units, components, or the like configured for controlling, monitoring, analyzing and / or timing the operations of various devices or components of the vacuum pumping system 600, as well as controlling or executing one or more steps of any of the methods disclosed herein. In addition to the various controllable devices or components described above in conjunction with FIG. 6, other devices may include, but are not limited to, electrical power (voltage) sources, timing controllers, clocks, frequency / waveform generators, processors, logic circuits, memories, databases, etc. One or more modules of the controller 700 may be, or be embodied in, one or more devices located outside or separate from the vacuum pumping system 600, for example, a computer workstation, desktop computer, laptop computer, portable computer, tablet computer, handheld computer, mobile computing device, personal digital assistant (PDA), smartphone, etc. One or more modules of the controller 700 may communicate with one or more other modules via one or more busses or other types of communication lines or wireless links, as appreciated by persons skilled in the art.

[0076] In the illustrated implementation, the controller 700 includes one or more electronics-based processors 702, which may be representative of a main electronic processor providing overall control, and one or more electronic processors configured for dedicated control operations or specific signal processing tasks (e.g., a graphics processing unit or GPU, a digital signal processor or DSP, an application-specific integrated circuit or ASIC, a field-programmable gate array or FPGA, etc.). The controller 700 also includes one or more memories 704 (volatile and / or non-volatile types, e.g., RAM and / or ROM) for storing data and / or software. Stored data may be organized, for example, in one or more databases or look-up tables. The controller 700 may also include one or more device drivers 706 for controlling one or more types of user interface devices and providing an interface between the user interface devices and components of the controller 700 communicating with the user interface devices. Such user interface devices may include user input devices 708 (e.g., keyboard, keypad, touch screen, mouse, joystick, trackball, and the like) and user output devices 710 (e.g., display screen, printer, visual indicators or alerts, audible indicators or alerts, and the like). In various implementations, the controller 700 may be considered as including one or more of the user input devices 708 and / or user output devices 710, or at least as communicating with them.

[0077] In some implementations, the controller 700 may also include one or more types of computer programs or software contained in memory and / or on one or more types of non-transitory (or tangible) computer-readable media. One or more devices of the controller 700 may be configured to receive and read (and optionally write to) the computer-readable media. The computer programs or software may contain non-transitory instructions (e.g., logic instructions) for controlling or performing various operations of the vacuum pumping system 600, such as the operations of the various devices described herein. The computer programs or software may include system software and application software. System software may include an operating system (e.g., a Microsoft Windows® operating system) for controlling and managing various functions of the controller 700, including interaction between hardware and application software. In particular, the operating system may provide a graphical user interface (GUI) displayable via a user output device 710, and with which a user may interact with the use of a user input device 708. Application software may include software configured to control or execute various operations of the vacuum pumping system 600, and / or some or all of the steps of any of the methods disclosed herein.

[0078] The controller 700 may also include a motor controller (or control module) 712 configured to control the operation of the motor 104 (e.g., on / off states, power supplied, drive shaft speed, etc.) and thus the rotational velocity of the orbiting scroll 280 and inlet and outlet pressures of the pump head 102 / 202 (FIGS. 1, 2 and 6). The controller 700 may also include one or more sensor interfaces 714 configured to receive and process feedback (e.g., measurement) signals received from one or more sensors / meters / data loggers provided with the vacuum pumping system 600, such as the inlet pressure sensor 614, outlet pressure sensor 616, current sensor 614, voltage sensor 618, run time meter 620, speed sensor 624, and temperature sensor 628 described above (FIG. 6). For example, the sensor interfaces 714 may be embodied in different pieces of firmware or other electronic circuitry that are part of a microcontroller of the controller 700. The sensor interfaces 714 may communicate with the motor controller 712 and other components of the controller 700 as needed to provide effective control of various operations of the vacuum pumping system 600 and the performing of any of the methods described herein. The firmware or other electronic circuitry embodying the motor controller 712 also may be provided with the same microcontroller that includes the sensor interfaces 714, or may be provided with separate hardware of the controller 700. The controller 700 may also include a data acquisition module (or DAQ) 716 configured to further condition or process the signals received by the sensor interface(s) 714 as needed for preparing data to be analyzed by the controller 700. The controller 700 may also include a wear analyzer (or analyzing module) configured to analyze the data and make the determinations in accordance with any of the methods described herein.

[0079] FIG. 8 is a flow diagram 800 illustrating an example of a method for predicting tip seal wear in a scroll pump according to an implementation of the present disclosure. The method may utilize the various hardware components, modules and structures described herein. The method starts with providing a scroll pump such as described herein (step 802). Accordingly, the scroll pump may include a pump inlet, a pump outlet, and a pumping stage. The pumping stage may include a first scroll and at least one (inboard or outboard) second scroll nested together. The first scroll and / or the second scroll is / are configured to orbit about a drive axis relative to the other of the first scroll and second scroll to create a moving pocket between the orbiting scroll and the fixed scroll effective to pump fluid from the pump inlet to the pump outlet. The first scroll includes at least one first scroll tip seal, and the second scroll includes at least one second scroll tip seal.

[0080] The scroll pump is operated, such as to evacuate (or “pump down”) a vacuum chamber such as described above. Specifically, the scroll pump is operated for a plurality of run times in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges (step 804). The durations of the successive run times are measured (step 806) (e.g., the accumulative hours of operation during each pressure regime are counted or logged). In addition, the pump inlet pressure during the operating of the scroll pump for each of the run times is determined by direct measurement of pressure (using a pressure gauge), or by calculation based on operating parameters having a correlation with pressure (e.g., current and / or voltage), as described above (step 808). A determination is then made (e.g., by the controller 632 / 700 described herein) as to whether at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal (step 810). The determining step 810 is based on: the duration of each run time measured; and respective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges. If the determination is positive—that is, if it is determined that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal—the scroll pump is shut down and the worn tip seal(s) is / are replaced in the manner described herein.

[0081] In an implementation, one or more steps of the method just described and illustrated in FIG. 8 may be controlled or performed by a controller including a processor, memory, and other components as appreciated by persons skilled in the art, such as the controller 632 / 700 described above in conjunction with FIGS. 6 and 7.

[0082] In an implementation, the flow diagram 800 may represent a scroll pump, or additionally a vacuum pumping system, configured to carry out the steps shown in the flow diagram 800. For this purpose, various components of the scroll pump 100 and / or vacuum pumping system 600 described and illustrated herein may be utilized.

[0083] It will be understood that one or more of the processes, sub-processes, and process steps described herein may be performed by hardware, firmware, software, or a combination of two or more of the foregoing, on one or more electronic or digitally-controlled devices. The software may reside in a software memory (not shown) in a suitable electronic processing component or system such as, for example, the system controller 632 or 700 schematically depicted in FIG. 6 or 7. The software memory may include an ordered listing of executable instructions for implementing logical functions (that is, “logic” that may be implemented in digital form such as digital circuitry or source code, or in analog form such as an analog source such as an analog electrical, sound, or video signal). The instructions may be executed within a processing module, which includes, for example, one or more microprocessors, general purpose processors, combinations of processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate array (FPGAs), etc. Further, the schematic diagrams describe a logical division of functions having physical (hardware and / or software) implementations that are not limited by architecture or the physical layout of the functions. The examples of systems described herein may be implemented in a variety of configurations and operate as hardware / software components in a single hardware / software unit, or in separate hardware / software units.

[0084] The executable instructions may be implemented as a computer program product having instructions stored therein which, when executed by a processing module of an electronic system (e.g., the system controller 632 or 700 schematically depicted in FIG. 6 or 7), direct the electronic system to carry out the instructions. The computer program product may be selectively embodied in any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as an electronic computer-based system, processor-containing system, or other system that may selectively fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this disclosure, a computer-readable storage medium is any non-transitory means that may store the program for use by or in connection with the instruction execution system, apparatus, or device. The non-transitory computer-readable storage medium may selectively be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device. A non-exhaustive list of more specific examples of non-transitory computer readable media include: an electrical connection having one or more wires (electronic); a portable computer diskette (magnetic); a random access memory (electronic); a read-only memory (electronic); an erasable programmable read only memory such as, for example, flash memory (electronic); a compact disc memory such as, for example, CD-ROM, CD-R, CD-RW (optical); and digital versatile disc memory, i.e., DVD (optical). Note that the non-transitory computer-readable storage medium may even be paper or another suitable medium upon which the program is printed, as the program may be electronically captured via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner if necessary, and then stored in a computer memory or machine memory.

[0085] It will also be understood that the term “in signal communication” or “in electrical communication” as used herein means that two or more systems, devices, components, modules, or sub-modules are capable of communicating with each other via signals that travel over some type of signal path. The signals may be communication, power, data, or energy signals, which may communicate information, power, or energy from a first system, device, component, module, or sub-module to a second system, device, component, module, or sub-module along a signal path between the first and second system, device, component, module, or sub-module. The signal paths may include physical, electrical, magnetic, electromagnetic, electrochemical, optical, wired, or wireless connections. The signal paths may also include additional systems, devices, components, modules, or sub-modules between the first and second system, device, component, module, or sub-module.

[0086] More generally, terms such as “communicate” and “in . . . communication with” (for example, a first component “communicates with” or “is in communication with” a second component) are used herein to indicate a structural, functional, mechanical, electrical, signal, optical, magnetic, electromagnetic, ionic or fluidic relationship between two or more components or elements. As such, the fact that one component is said to communicate with a second component is not intended to exclude the possibility that additional components may be present between, and / or operatively associated or engaged with, the first and second components.

[0087] It will be understood that various aspects or details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation—the invention being defined by the claims.

Examples

Embodiment Construction

[0025]In this disclosure, all “implementations,”“aspects,”“examples,” and “embodiments” described are considered to be non-limiting and non-exclusive. Accordingly, the fact that a specific “implementation,”“aspect,”“example,” or “embodiment” is explicitly described herein does not exclude other “implementations,”“aspects,”“examples,” and “embodiments” from the scope of the present disclosure even if not explicitly described. In this disclosure, the terms “implementations,”“aspect,”“example,” and “embodiment” are used interchangeably, i.e., are considered to have interchangeable meanings.

[0026]In this disclosure, the term “substantially,”“approximately,” or “about,” when modifying a specified numerical value, may be taken to encompass a range of values that include + / −10% of such numerical value, unless specifically indicated otherwise.

[0027]FIG. 1 is a cross-sectional elevation view of an example of a scroll pump (assembly) 100 in which the subject matter disclosed herein may be imp...

Claims

1. A method for predicting tip seal wear in a scroll pump, the method comprising:providing a scroll pump comprising a pump inlet, a pump outlet, and a pumping stage, wherein the pumping stage comprises a first scroll and a second scroll nested together, at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to pump fluid from the pump inlet to the pump outlet, the first scroll comprises a first scroll tip seal, and the second scroll comprises a second scroll tip seal;operating the scroll pump for a plurality of run times in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges;measuring a duration of each run time;determining the pump inlet pressure during the operating of the scroll pump for each of the run times; anddetermining that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal, wherein the determining is based on:the duration of each run time measured; andrespective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges.

2. The method of claim 1, comprising, after determining that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal, at least one of:shutting down the scroll pump and replacing the first scroll tip seal and / or the second scroll tip seal with a new first scroll tip seal and / or a new second scroll tip seal;producing a user-interpretable output indicating that tip seal maintenance is required.

3. The method of claim 1, wherein the determining that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal comprises determining a current value of cumulative tip seal wear, and determining that the current value of cumulative tip seal wear equals or exceeds a threshold value of cumulative tip seal wear.

4. The method of claim 3, wherein:the plurality of run times comprises a first run time Trun1, a second run time Trun2, and an Nth run time TrunN;the plurality of expected service lives comprises a first expected service life Tesl1, a second expected service life Tesl2, and an Nth expected service life TeslN; andthe determining of the current value of cumulative tip seal wear, CW, is calculated from the following equation:CW=Trun⁢1Tesl⁢1+Trun⁢2Tesl⁢2+…+Trun⁢NTesl⁢N.

5. The method of claim 3, wherein:the plurality of run times comprises a first run time Trun, and a second run time Trun2;the plurality of expected service lives comprises a first expected service life Tesl1 and a second expected service life Tesl2 andthe determining of the current value of cumulative tip seal wear, CW, is calculated from the following equation:CW=Trun⁢1Tesl⁢1+Trun⁢2Tesl⁢2.

6. The method of claim 1, comprising one of:wherein the scroll pump is a vacuum scroll pump, and the operating of the scroll pump comprises evacuating a vacuum chamber communicating with the pump inlet;wherein the scroll pump is a scroll compressor, and the operating of the scroll pump comprises outputting the fluid toward a destination that utilizes compressed fluid and communicates with the pump outlet.

7. The method of claim 1, comprising one of:wherein the first scroll is an orbiting scroll and the second scroll is a fixed scroll, and the first scroll is configured to orbit about the drive axis relative to the second scroll;wherein the first scroll and the second scroll are co-rotating scrolls configured to orbit about the drive axis relative to each other.

8. The method of claim 1, wherein the determining of the pump inlet pressure is based on at least one of:measuring the pump inlet pressure by using a pressure sensor of the scroll pump;calculating the pump inlet pressure based on measurements made by a current sensor monitoring operation of a motor of the scroll pump;calculating the pump inlet pressure based on measurements made by a voltage sensor monitoring operation of a motor of the scroll pump;calculating the pump inlet pressure based on measurements made by a current sensor and a voltage sensor monitoring operation of a motor of the scroll pump.

9. A scroll pump, comprising:a pump inlet;a pump outlet;a pumping stage comprising a first scroll and a second scroll nested together, at least one of the first scroll or the second scroll is configured to orbit about a drive axis relative to the other of the first scroll and the second scroll to pump fluid from the pump inlet to the pump outlet;a first scroll tip seal mounted to the first scroll;a second scroll tip seal mounted to the second scroll;a sensor configured to measure pump inlet pressure or to measure an operating parameter from which the pump inlet pressure can be calculated;a runtime meter configured to measure a plurality of run times during which the scroll pump operates in a plurality of respective pressure ranges of pump inlet pressure, wherein each pressure range is different from the other pressure ranges; anda controller configured to determine that at least one of the first scroll tip seal or the second scroll tip seal is a worn tip seal, wherein the determining is based on:the duration of each run time measured; andrespective durations of a plurality of expected service lives of the first scroll tip seal and the second scroll tip seal, wherein each expected service life corresponds to a respective one of the pressure ranges.

10. The scroll pump of claim 9, wherein the determining performed by the controller comprises determining a current value of cumulative tip seal wear, and the controller is further configured to determine that the current value of cumulative tip seal wear equals or exceeds a threshold value of cumulative tip seal wear.

11. The scroll pump of claim 10, wherein:the plurality of run times comprises a first run time Trun1, a second run time Trun2, and an Nth run time TrunN;the plurality of expected service lives comprises a first expected service life Tesl1, a second expected service life Tesl2, and an Nth expected service life TeslN; andthe determining of the current value of cumulative tip seal wear, CW, is calculated from the following equation:CW=Trun⁢1Tesl⁢1+Trun⁢2Tesl⁢2+…+Trun⁢NTesl⁢N.

12. The scroll pump of claim 10, wherein:the plurality of run times comprises a first run time Trun, and a second run time Trun2;the plurality of expected service lives comprises a first expected service life Tesl1 and a second expected service life Tesl2 andthe determining of the current value of cumulative tip seal wear, CW, is calculated from the following equation:CW=Trun⁢1Tesl⁢1+Trun⁢2Tesl⁢2.

13. The scroll pump of claim 9, comprising one of:wherein the scroll pump is a vacuum scroll pump, and the pump inlet is configured to communicate with a vacuum chamber,wherein the scroll pump is a scroll compressor, and the pump outlet is configured to communicate with a destination that utilizes compressed fluid.

14. The scroll pump of claim 9, comprising one of:wherein the first scroll is an orbiting scroll and the second scroll is a fixed scroll, and the first scroll is configured to orbit about the drive axis relative to the second scroll;wherein the first scroll and the second scroll are co-rotating scrolls configured to orbit about the drive axis relative to each other.

15. The scroll pump of claim 9, wherein the sensor comprises at least one of: a pressure sensor; a current sensor monitoring operation of a motor of the scroll pump; a voltage sensor monitoring operation of a motor of the scroll pump.

16. A non-transitory computer-readable medium comprising instructions stored thereon, that when executed on a processor, control or perform one or more of the steps of the method of claim 1.

Images