Seal for scroll pump
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- EDWARDS LTD
- Filing Date
- 2026-01-28
- Publication Date
- 2026-08-06
Smart Images
Figure GB2026050103_06082026_PF_FP_ABST
Abstract
Description
[0001] SEAL FOR SCROLL PUMP
[0002] FIELD OF THE INVENTION
[0003] The present invention relates to channel seals for scroll pumps.
[0004] BACKGROUND
[0005] Scroll pumps are a known type of pump used in various industries to pump fluid using the relative motion of two intermeshed scrolls. Each scroll includes a base from which a spiral wall extends to define a spiral channel.
[0006] Scroll pumps include seals to prevent leakage of fluid from various parts of the scroll pump. Seals may include tip seals, positioned at the tip of the spiral wall, and channel seals, positioned at the base of the spiral channel.
[0007] Channel seals have advantages in compactness and sealing performance over tip seals; however, challenges arise when matching the channel seals to the scrolls. Typically, a scroll pump includes a channel seal positioned at the base of each spiral channel. The height of the channel seals must match the scrolls to achieve sufficient sealing. For example, if one channel seal is too thick it will push the scrolls apart slightly, resulting in a small leakage path across the other channel seal. Since it is difficult to machine the channel seals and scrolls accurately to the tolerances required, a period of operation is required to wear the channel seals down until a near perfect match, and thus optimal sealing, is achieved. This period of operation is herein referred to as bedding-in.
[0008] The present invention provides a channel seal optimised to speed up bedding-in, such that channel seals are matched after a shorter running period.
[0009] SUMMARY OF THE INVENTION
[0010] According to a first aspect, the present invention provides a channel seal for a scroll pump. The channel seal comprises a wear surface which is subject to wear during operation of the scroll pump, wherein at least a portion of the wear surface is textured.A scroll pump typically comprises two intermeshing scrolls, each having a base from which a spiral wall extends to define a spiral channel. In use, the channel seal is positioned on the base of a spiral channel of one of the scrolls to provide a seal between the base of that scroll and the tip of the spiral wall of the other scroll.
[0011] Bedding-in is required to wear down the channel seal such that the height of the channel seal matches the scrolls. In other words, the channel seal is worn down until the height of the channel seal is equal to the spacing / axial offset between the base of the scroll and the tip of the wall of the other scroll.
[0012] The textured portion of the wear surface acts to reduce the amount of material required to be removed or worn-away from the channel seal during bedding-in. In other words, the textured portion of the wear surface has a lower density than a comparatively smoother surface. This advantageously reduces the bedding-in time, since the textured portion of the wear surface will wear more quickly than a comparatively smoother surface.
[0013] The textured portion of the wear surface may comprise or be provided by a plurality of protrusions. The plurality of protrusions may be a repeating pattern of protrusions. In this way, the pattern of protrusions may advantageously repeat in a consistent and predictable manner, such that wear is consistent and predictable. Optionally, the textured portion of the wear surface may advantageously comprise or be provided by a regular and repeating pattern of protrusions. The pattern of protrusions may alternatively be irregular. The plurality of protrusions may be formed by pressing, etching or additive manufacture, for example. The protrusions are optionally pillars and / or depositions, for example.
[0014] Preferably, the plurality of protrusions comprises a pattern of ridges. In other words, the textured portion of the wear surface may be provided by a pattern of ridges, the pattern of ridges optionally being a repeating pattern of ridges. The pattern of ridges is preferably a regular and repeating pattern of ridges. The pattern of ridges may alternatively be irregular. The pattern of ridges may be formed by pressing, etching or additive manufacture, for example.
[0015] Alternatively, the textured portion of the wear surface may be provided by an array of cavities, for example in the case of a foam or fibrous mesh.- 3 -
[0016] Where the plurality of protrusions comprises a pattern of ridges, the pattern of ridges may comprise at least a first set of parallel ridges extending in a first direction and a second set of parallel ridges extending in a second direction at an angle to the first direction. Preferably, the first direction is substantially perpendicular to the second direction, such that the first and second sets of parallel ridges form a substantially grid-like pattern of ridges. The grid-like pattern of ridges may form a plurality of substantially square or rectangular pockets within the textured portion. Such a grid¬ like pattern of ridges advantageously simplifies the manufacture process of the channel seal, which will be explained in more detail in later aspects of the present invention. Furthermore, a pattern of intersecting ridges, whether grid-like or otherwise, advantageously acts to minimise leakage in multiple directions. In other words, leakage is prevented across the pockets formed between adjacent intersecting ridges.
[0017] It should be appreciated that the pattern of ridges may include more than two sets of parallel ridges (for example, three, four, five, etc.). The ridges of each set of parallel ridges may follow any path along their length, for example straight, curved or winding. Each set of parallel ridges may extend in varied directions and at varied angles relative to one another, such that a wide range of patterns may be formed, including but not limited to triangular and hexagonal. Alternatively, the pattern of ridges may comprise a plurality of curved or circular ridges.
[0018] The height of each protrusion may range from 20 to 500 microns and preferably from 20 to 100 microns. The height of each protrusion is the distance from the foot, or base, of the protrusion to the tip of the protrusion. Preferably, the height is equal for all protrusions.
[0019] Where the plurality of protrusions comprises a pattern of ridges, the height of each ridge may accordingly range from 20 to 500 microns and preferably from 20 to 100 microns. The height of each ridge is the distance from the foot of the ridge to the tip of the ridge. Preferably, the height of each ridge is constant along its length.
[0020] Preferably, the height is substantially equal for all ridges.
[0021] The width of each protrusion may be constant along the height of the protrusion. Alternatively, each protrusion may narrow in a direction towards the tip of said protrusion. This narrowing may occur linearly or non-linearly in the directionextending towards the tip, to form differing cross-sections of the protrusion, including but not limited to trapezoid, parallelogram, triangular or semi-circular. This may result in a pointed or curved tip for example.
[0022] Accordingly, where the plurality of protrusions comprises a pattern of ridges, the width of each ridge may be constant along the height of the ridge. Alternatively, each ridge may narrow in a direction extending towards the tip of said ridge. For example, the ridge may narrow in a direction extending from the foot of the ridge towards the tip of said ridge. This narrowing may occur linearly or non-linearly in the direction extending towards the tip, to form differing ridge cross-sections, including but not limited to trapezoid, parallelogram, triangular or semi-circular. This may result in a pointed or curved tip for example. Preferably, each ridge has a constant cross¬ section along its length (i.e. the narrowing is constant along the length of each ridge). Preferably, the ridge cross-section is the same for all ridges. The ridge cross-section is the cross-section perpendicular to the lengthwise direction of the ridge.
[0023] The wear surface may comprise a first portion and a second portion, wherein the first portion of the wear surface is the textured portion and the second portion of the wear surface is smoother than the first portion, it should be appreciated that the term smoother herein takes its conventional meaning and means that the second portion of the wear surface comprises one or more of: fewer surface irregularities or protrusions than the first portion of the wear surface, no surface irregularities or protrusions, smaller surface irregularities or protrusions than the first portion of the wear surface, ora lower surface roughness than the first portion of the wear surface, for example.
[0024] The channel seal may comprise an inner portion and an outer portion extending around the periphery of the inner portion, wherein the inner portion comprises the first portion of the wear surface and the outer portion comprises the second portion of the wear surface. In other words, the inner portion comprises the textured portion of the wear surface and the wear surface of the outer portion is smoother than the textured portion of the wear surface. The wear surface of the outer portion may also be referred to herein as the smooth portion. As a result, the wear surface of the outer portion is more wear resistant than the wear surface of the inner portion.In use, the outer portion of the channel seal is positioned between an outer portion of the scrolls. The outer portion of the scrolls between which the outer portion of the channel seal is positioned is a portion of the scrolls falling outside each respective spiral wall. As a result, the wear surface of the outer portion of the channel seal (i.e. the smooth portion) typically functions as a bearing area.
[0025] The wear surface of the outer portion (i.e. the smooth portion) may be axially offset below the wear surface of the inner portion (i.e. the textured portion). For example, the wear surface of the outer portion may be axially offset from the tip of each protrusion of the textured portion. Preferably, the axial offset is equal to the height of each protrusion. In other words, the foot of each protrusion is in the same plane as the wear surface of the outer portion. Since the outer portion typically functions as a bearing area, providing an axial offset below the height of each protrusion may eliminate the need to wear the outer portion during bedding in. This advantageously ensures that a minimum bedding-in period is maintained, even when an outer portion with a wear surface that is relatively smoother and thus more wear resistant than the textured portion is provided.
[0026] The channel seal may comprise an inner portion and an outer portion extending around the periphery of the inner portion, wherein the outer portion is formed from a harder material than the inner portion. Forming the outer portion from a harder material advantageously increases the wear resistance of the outer portion, supporting its function as a bearing area.
[0027] The outer portion may be a separate annular or ring-shaped portion arranged about the inner portion. Alternatively, the outer portion may be over moulded with the inner portion to achieve a one-piece seal.
[0028] The outer portion and inner portion may be formed as a single piece from the same material, such that the outer portion is integral with the inner portion.
[0029] The channel seal may comprise a base portion on which the textured portion, or first portion, of the wear surface is disposed. For example, the plurality of protrusions or pattern of ridges may protrude from the base portion. The textured, or first portion, of the wear surface may be formed on, applied to or supported by the base portion, for example.The textured portion, or first portion, may have a first density and the base portion may have a second density greater than the first. As the channel seal continues to wear during operation, the base portion engages with the spiral wall of the other scroll. Since the base portion has a higher density when compared to the textured portion, or first portion, the base portion has a lower wear rate. This advantageously increases the wear life of the channel seal after the textured portion, or first portion, has worn away, in other words, the wear life of the channel seal is Increased after bedding-ln.
[0030] Preferably, the base portion is formed from a harder material than the textured portion, or first portion. For example, the base portion may first be formed from a harder material, onto which a softer material may be coated or over moulded to form the textured portion, or first portion, of the wear surface. The texture may be applied to or formed using the softer material by etching or pressing, for example.
[0031] Alternatively, the texture may be formed by printing or depositing a plurality of protrusions directly onto the base portion, to form the textured portion, or first portion. This further improves the bedding-in time due to the higher wear rate of the softer textured portion, or first portion. The wear life of the channel seal after bedding-in may also be increased, since harder materials may be used for the base portion than have previously been considered feasible for use in channel seals due to the bedding-in process. The base portion may be formed as a single piece with the outer portion of the channel seal, in other words, for ease of manufacture the base portion and outer portion may be integral.
[0032] Each protrusion may protrude in a direction which is angled to the surface of the base portion (to define an “angle of protrusion”). For example, each ridge may protrude in a direction which is angled to the surface of the base portion. For protrusions or ridges with a cross-section comprising two parallel sides, for example a trapezoid, parallelogram or rectangular cross-section, the angle of protrusion is the smallest angle between a side and the surface of the base from which the protrusion or ridge protrudes. For protrusions or ridges with a triangular cross-section, the angle of protrusion is the angle between the bisector and the surface of the base portion from which the protrusion or ridge protrudes. For protrusions or ridges with a rounded or semi-circular cross-section, the angle of protrusion is the angle between a linetaken from the tip of the protrusion or ridge to midway along the width of the protrusion or ridge at the base portion and the surface of the base portion from which the protrusion or ridge protrudes. The ridge cross-section is the cross-section perpendicular to the lengthwise direction of the ridge. Preferably, the angle of protrusion is a right angle. Preferably, the angle of protrusion is constant along the length of each protrusion or ridge. Preferably, the angle of protrusion is equal for all protrusions or ridges.
[0033] The base portion is preferably a solid portion. Alternatively, the base portion may be a foam or a mesh.
[0034] According to a second aspect, the present invention provides a scroll pump comprising a first scroll and a second scroll intermeshing with the first scroll, each of the scrolls having a base and a spiral wall defining a spiral channel, and a drive for effecting relative orbiting motion between the scrolls. The scroll pump also comprises the channel seal of the first aspect arranged within the spiral channel of one of the scrolls for engaging the spiral wall of the other scroll. In particular, the wear surface of the channel seal engages with the tip of the spiral wall of the other scroll.
[0035] During operation of the scroll pump the textured portion of the channel seal engages with the tip of the spiral wall of the other scroll. Due to the high wear rate provided by the textured portion, the textured portion of the surface wears down quickly during bedding-in, until the height of the channel seal matches the spacing between the scrolls, as previously described. This advantageously reduces the time required for bedding-in, when compared to a conventional channel seal formed with uniform properties and a uniform density across its height. Since bedding-in typically occurs during the manufacturing process, this advantageously reduces the manufacturing time of the scroll pump.
[0036] Where the textured portion comprises a pattern of ridges, the maximum distance between adjacent ridges is preferably less than the width of the spiral wall engaging the channel seal. In other words, in use, there is preferably at least one ridge engaging with the tip of said spiral wall at any given time to form a seal across the entire length of said spiral wall. This acts to minimise leakage across the pockets between adjacent ridges during bedding-in. Where the textured portion is provided by a plurality of pillars and / or alternative protrusions, the maximum distance betweenadjacent pillars and / or alternative protrusions is preferably less than the width, or thickness of the spiral wall engaging the channel seal, such that there is at least one pillar and / or protrusion engaging with the tip of said spiral wall at any given time to form a seal across the entire length of said spiral wall at any given time.
[0037] The scroll pump may comprise more than one channel seal. For example, the scroll pump may comprise a further said channel seal arranged within the spiral channel of the other scroll for engaging the spiral wall of said one of the scrolls. Where more than one channel seal is included within the scroll pump, bedding-in is considered complete once all channel seals have made contact with the tip of the spiral wall with which it is configured to engage.
[0038] The scroll pump may be a scroll vacuum pump.
[0039] In a further aspect, the present invention provides a method of manufacturing a channel seal for a scroll pump, the method comprising providing a blank, or base portion, and texturing a surface of the blank that corresponds to the wear surface of the channel seal during operation of the scroll pump.
[0040] Texturing may be achieved by pressing, laser-etching, electro chemical machining (ECM) or any other suitable technique. Preferably, pressing is used as it is simple and cost effective.
[0041] Texturing may also be achieved by providing a mould, wherein the mould is shaped to define a textured surface, inserting a blank into said mould and supplying material to said mould to form a textured portion by overmoulding.
[0042] The method may also comprise cutting the textured blank to define the channel seal. This may be applicable where, prior to texturing, the blank does not fit the spiral channel of the scroll to which the channel seal is to be arranged during use, for example where the blank forms a sheet from which multiple channel seals are cut. Alternatively, prior to texturing, the blank may already fit the spiral channel of the scroll to which the channel seal is to be arranged during use.
[0043] The method may also comprise fitting a separate outer portion, such as an annular ring, to the channel seal. For example, the outer portion may be fit around the blankbefore or after texturing. Preferably the outer portion is formed from a harder material than the textured blank.
[0044] In an alternative aspect, the present invention provides a method for manufacturing a channel seal for a scroll pump comprising providing a mould and injecting material into the mould to form the channel seal, wherein the mould is shaped to define a channel seal having a base portion and integral textured portion which is subject to wear during operation of the scroll pump, it should be appreciated that the channel seal of the present invention may also be manufactured by additive manufacture. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:
[0046] Figure 1 illustrates a first embodiment of a channel seal according to the present invention.
[0047] Figure 2a illustrates a schematic top plan view of a portion of the channel seal of Figure 1.
[0048] Figure 2b illustrates a schematic first perspective view of a portion of the channel seal of Figure 1.
[0049] Figure 2c illustrates a schematic second perspective view of a portion of the channel seal of Figure 1.
[0050] Figure 3a illustrates a schematic cross-sectional view of a portion of a channel seal according to a second embodiment of the present invention.
[0051] Figure 3b illustrates a schematic cross-sectional view of a portion of a channel seal according to a third embodiment of the present invention.
[0052] Figure 3c illustrates a schematic cross-sectional view of a portion of a channel seal according to a fourth embodiment of the present invention.
[0053] Figure 4 illustrates a schematic cross-sectional view of a scroll pump comprising the channel seal of Figure 1.Figure 5 illustrates a schematic view of the channel seal of previous embodiments engaging with a spiral wall of a scroll during operation.
[0054] Figure 6 illustrates a fifth embodiment of a channel seal according to the present invention.
[0055] Figure 7 illustrates a schematic cross-sectional view of a portion of the channel seal of Figure 6.
[0056] Figure 8 illustrates a schematic cross-sectional view of a portion of a channel seal according to a sixth embodiment of the present invention.
[0057] Figure 9 illustrates a schematic cross-sectional view of a portion of a channel seal according to a seventh embodiment of the present invention.
[0058] Figure 10 illustrates a schematic cross-sectional view of a portion of a channel seal according to an eighth embodiment of the present invention.
[0059] DETAILED DESCRIPTION OF THE DRAWINGS
[0060] Figure 1 illustrates a first embodiment of a channel seal 10a according to the present invention. The channel seal 10a exhibits a spiral geometry to match the spiral channel of the scroll in which the channel seal is designed to be arranged during use. In this embodiment, the entirety of the surface which is subject to wear during operation of the scroll pump (hereafter referred to as wear surface 12a) is textured. Figure 2a illustrates a top plan view of a portion of the channel seal 10a of Figure 1. The texture is provided by a plurality of protrusions. In the depicted embodiment, the texture is provided by a first set of parallel ridges 14a (hereafter referred to as first ridges), which extend in a first direction, and a second set of parallel ridges 16a (hereafter referred to as second ridges), which extend in a second direction. The first direction is at a right angle to the second direction, resulting in a grid-like pattern of intersecting ridges over the entirety of the wear surface 12a.
[0061] In use, the channel seal undergoes bedding-in, during which the first and second ridges 14a, 16a are worn down. The textured portion provided by the first and second ridges 14a, 16a has a lower wear resistance when compared to the comparatively smoother surface of conventional channel seals. In other words, the textured portionwears faster when compared to the comparatively smoother surface of conventional channel seals. This advantageously reduces the bedding-in time.
[0062] The first ridges 14a are evenly spaced apart, such that the distance between adjacent first ridges 14a is constant. Similarly, the second ridges 16a are evenly spaced apart, such that the distance between adjacent second ridges 16a is constant. The distance between adjacent first ridges 14a is equal to the distance between adjacent second ridges 16a, resulting in a grid-like pattern of square pockets 18a across the textured portion. The textured portion is therefore provided by a regular and repeating pattern of ridges 14a, 16a,
[0063] The maximum spacing between adjacent first and / or second ridges 14a, 16a is preferably less than the width of the spiral wall for engaging the channel seal 10a during use, as will be explained in more detail with reference to Figure 5. In the present embodiment, the maximum spacing between adjacent first and / or second ridges 14a, 16a is the diagonal distance D from one corner of each square pocket 18a to the other. Ensuring that this distance D is less than the width of the spiral wall for engaging the channel seal 10a during use guarantees that there is always at least one ridge 14a, 16a in contact with the spiral wall to form a seal during bedding-in. Figures 2b-c illustrate perspective views of a portion of the channel seal 10a of Figure 2a. The first and second ridges 14a, 16a protrude from a base portion 20a of the channel seal 10a. In use, the channel seal 10a undergoes bedding-in, during which the first and second ridges 14a, 16a are worn down, exposing the smoother base portion 20a to the spiral wall and maximizing wear resistance of the channel seal 10a.
[0064] Figure 3a illustrates a cross-sectional view of a second embodiment of a channel seal 10b. The textured portion of the channel seal 10b is provided by a first set of parallel ridges (first ridges) 14b and a second set of parallel ridges (not shown). The cross-sectional view is taken through a plane perpendicular to the lengthwise direction of the first ridges 14b. The first ridges 14b have a constant width from the foot of each ridge to its tip 15b. In other words, the first ridges 14b have a constant thickness from the foot of each ridge to its tip 15b.Figure 3b illustrates a cross-sectional view of a third embodiment of a channel seal 10c. The textured portion of the channel seal 10c is provided by a first set of parallel ridges (first ridges) 14c and a second set of parallel ridges (not shown). The cross- sectional view is taken through a plane perpendicular to the lengthwise direction of the first ridges 14c. The first ridges 14c have a width that reduces in the direction from the foot of each ridge to its tip 15c, such that the first ridges 14c narrow in the direction from the foot to the tip 15c. The width reduces linearly, resulting in a triangular ridge cross-section.
[0065] Figure 3c illustrates a cross-sectional view of a fourth embodiment of a channel seal 10d. The textured portion of the channel seal 10d is provided by a first set of parallel ridges (first ridges) 14d and a second set of parallel ridges (not shown). The cross-sectional view is taken through a plane perpendicular to the lengthwise direction of the first ridges 14d. The first ridges 14d have a width that reduces in the direction from foot of each ridge to its tip 15d, such that the ridges narrow in the direction from the foot to the tip 15d. The width reduces non-linearly, resulting in a substantially semi-circular ridge cross-section.
[0066] The plurality of protrusions or ridges of the invention may have any of a number of cross-sections. For example, the first ridges 14a and second ridges 16a of the arrangement of Figures 1 to 2c may take any of the forms depicted in Figures 3a to 3c in cross-section.
[0067] Further, it should be appreciated that the cross-sections of the protrusions or ridges are not limited to the above-described embodiments and one or more of a multitude of ridge cross-sections may be used. It should also be appreciated that the cross¬ sections of any additional sets of ridges (not shown) may also vary in a similar way, though preferably the cross-sections of each set of ridges is the same as for every other set of ridges. Whilst above-described embodiments show the ridges narrowing from the foot of each ridge to its tip, it should be appreciated that the narrowing need not extend along the entire height of the ridge. For example, the narrowing may extend only along a portion of the height of the ridge in the direction towards the tip of said ridge.
[0068] Each ridge 14b,14c,14d protrudes from a base portion 20b,20c,20d at an angle to a surface 22b,22c,22d of the base portion which is subject to wear during use. Inthese embodiments, the angle of protrusion is a right angle, but the angle may be an acute angle.
[0069] The height of each ridge hR is the distance from the foot of said ridge to its tip 15b, as illustrated in Figure 3a. The height of each ridge hR may range from 20 to 500 microns, preferably from 20 to 100 microns. The height of the base portion hB is typically larger than the height of the ridges hR. The overall height of the channel seal hS is equal to the sum of the heights of the base portion hB and the highest of the ridges hR.
[0070] Figure 4 illustrates a scroll pump 100 comprising the channel seal 10a of Figure 1. The scroll pump 100 comprises a first scroll 120 and a second scroll 130 intermeshing with the first scroll 120. Each of the scrolls 120,130 comprise a base 122,132 and a spiral wall 124,134 defining a spiral channel (not labelled). The first spiral wall 124 extends perpendicularly from the first base 122 towards the second base 132, such that the tip of the first spiral wall 124 is proximate but not in contact with an opposing surface of the second base 132. Similarly, the second spiral wall 134 extends perpendicularly from the second base 132 towards the first base 122, such that the tip of the second spiral wall 134 is proximate to but not in contact with an opposing surface of the first base 122. The first and / or second spiral walls 124,134 may be integrally formed with the respective first and / or second base 122,132.
[0071] A channel seal 10a is arranged within each of the spiral channels (not labelled), such that one of the channel seals 10a is sandwiched between the end surface of the second spiral wall 134 and the opposing surface of the first base 122 and the other of the channel seals 10a is sandwiched between the end surface of the first spiral wall 124 and the opposing surface of the second base 132. The first scroll 120 and second scroll 130 may be biased together by a biasing apparatus (not shown) of the scroll pump (e.g. one or more springs).
[0072] In this embodiment, the housing 110 and the first scroll 120 together define an overall housing of the scroll pump 100. However, it should be appreciated that the first scroll 120 may not define any of the overall housing of the scroll pump 100.A drive 150 is coupled to the second scroll 130 for effecting relative orbiting motion between the first and second scrolls 120,130 during operation of the scroll pump. During operation of the scroll pump 100, fluid is pumped from an inlet to an outlet of the scroll pump 100 (not shown) via the spiral channel. The precise physical mechanism by which fluid is pumped is well understood and will not be described herein for the sake of brevity.
[0073] The channel seals 10a provide axial seals to minimise leakage of fluid axially between different sections of the spiral channels during operation of the scroll pump 100. To ensure maximum sealing, the height of the channel seals 10a must match the first and second scrolls 120,130.
[0074] During operation of the scroll pump 100, due to the relative orbiting motion of the first and second scrolls 120,130, each of the relative end surfaces of the first and second spiral walls 122,124 rub against the relative channel seal 10a. Thus, each of the channel seals 10a are subject to wear during use overtime. A surface of the channel seals 10a that is subject to wear during operation of the scroll pump 100 is textured. As a result, it has a lower wear resistance when compared to a comparatively smooth surface of conventional channel seals. Therefore, there is a period during initial operation of the scroll pump 100 in which the textured surface of the channel seals 10a wears relatively quickly until the base portion of the channel seal is exposed. This proves advantageous in reducing the time required for bedding-in, as previously described herein.
[0075] It should be appreciated that the channel seals 10b-1 Oh described in Figures 3 and 5-10 can also be applied to a scroll pump as depicted in Figure 4.
[0076] Figure 5 illustrates a view of the channel seal 10b of Figure 3a engaging with a spiral wall 124 of the scroll pump 100 during operation. It should be appreciated that the depicted arrangement also applies to the channel seals 10a and 10c-h of Figs 1, 2, 3b, 3c and 6-10 and that the channel seal of Figure 3a has been shown here as a representative example. The spacing between adjacent ridges of the set of parallel ridges 14b is denoted S. The spacing S at its maximum between adjacent ridges, or protrusions, is less than the width of the spiral wall, denoted W. In other words, S < W. It should be appreciated that the diagonal distance D of the embodiment of Figure 2a represents the maximum spacing S of the arrangement of Figure 2a and Figure 5.In other words, the largest dimension of each pocket formed between adjacent ridges is smaller than the width of the spiral wall. This advantageously ensures that, during operation, the tip 15b of at least one ridge of the pattern of first ridges 14b engages with the tip of the spiral wall 124 at any given time to form a seal across the entire length of said spiral wall 124. This acts to minimise leakage across the pockets between adjacent ridges of the pattern of ridges 14b during bedding-in.
[0077] Figure 6 illustrates a fifth embodiment of a channel seal 10e according to the present invention. The wear surface of the channel seal 10e has a first portion 24e and a second portion 26e. The first portion 24e is the textured portion of the wear surface, whilst the second portion 26e of the wear surface is smoother than the first portion 24e. In other words, only the first portion 24e of the wear surface is textured. The texture is provided by a pattern of first and second ridges, similar to those previously described with reference to Figures 1-3c and 5, for example. The second portion 26e of the wear surface extends around the periphery of the first portion 24e.
[0078] In use, the second portion 26e of the wear surface of the channel seal 10e is positioned between respective outer portions of the scrolls to provide a higher degree of wear resistance in this region. The outer portions of the scrolls, between which the second portion 26e of the wear surface of the channel seal 10e is positioned, is a portion of the scrolls falling outside each respective spiral wall. The second portion 26e of the wear surface therefore functions as a bearing area.
[0079] Figure 7 illustrates a cross-sectional view through the channel seal 10e of Figure 6, for example. The cross-sectional view is taken through a plane perpendicular to a lengthwise direction of the first ridges 14e (second ridges not shown) formed at the first portion 24e of the wear surface. The second portion 26e of the wear surface is axially offset below the tip 15e of each first ridge 14e. Preferably, the axial offset, denoted A, is equal to the height of each first ridge 14e. In other words, the wear surface of the second portion 26e is in the same plane as the foot of each first ridge 14e. The second portion 26e of the wear surface typically functions as a bearing area, hence providing an axial offset below the height of each of the first ridges 14e may eliminate the need to wear the second portion 26e of the wear surface during bedding in. This advantageously ensures that a minimum bedding-in period is maintained.The channel seal 10e has a base portion 32e on which the first portion 24e of the wear surface is disposed. In other words, the channel seal 10g has a base portion 32g on which the textured portion of the wear surface is disposed. In the depicted embodiment the surface of the base portion 32e that extends around the periphery of the first portion 24e directly forms the second portion 26e of the wear surface. The textured portion may be formed integrally with the base portion 32e as depicted, or may be formed separately from the base portion 32e. Further, the channel seal 10e can be described as having an inner portion comprising the first portion 24e, or textured portion, of the wear surface and an outer portion comprising the second portion 26e of the wear surface.
[0080] It should be appreciated that whilst the second ridges are not shown in Figure 7, the same principle applies to the second ridges, which preferably have substantially the same height as the first ridges 14e.
[0081] Figure 8 illustrates a cross-sectional view of a channel seal 10f according to a sixth embodiment of the present invention. The channel seal 10f is similar to the channel seal 1 Oe, of Figures 6-7, in that the wear surface of the channel seal 10f has a first portion 24f and a second portion 26f. The first portion 24f is the textured portion of the wear surface, provided by a pattern of first and second ridges. The cross- sectional view is taken through a plane perpendicular to the lengthwise direction of the first ridges 14f (second ridges not shown) formed at the first portion 24f of the wear surface. The second portion 26f of the wear surface is smoother than the first portion 24f and extends around the periphery of the first portion 24f. The second portion 26f of the wear surface is axially offset below the tip 15f of each first ridge 14f. Preferably, the axial offset, denoted A’, is equal to the height of each first ridge 14f. In other words, the wear surface of the second portion 26f is in the same plane as the foot of each first ridge 14f.
[0082] The channel seal 10f further has an inner portion 28f and an outer portion 30f. The outer portion 30f extends around the periphery of the inner potion 28f. The inner portion 28f comprises the first portion 24f of the wear surface. In other words, the wear surface of the inner potion 28f is textured. The inner portion 28f exhibits a spiral geometry to match the spiral channel of the scroll in which the channel seal 20f is designed to be arranged during use. The outer portion 30f comprises the secondportion 26f of the wear surface. In other words, the wear surface of the outer portion 30f is smoother than the textured portion.
[0083] In this particular embodiment, the outer portion 30f is formed from a harder material than the inner portion 28f. In particular, the outer portion 30f is formed from a separate annular ring of harder material than the inner portion 28f. This further improves the wear resistance of the outer portion 30f and second portion 26f of the wear surface and thus its performance as a bearing surface after bedding-in. It should however be appreciated that the outer portion 30f may be formed from the same material as the inner portion 28f.
[0084] In use, the outer portion 30f of the channel seal 10f is positioned between respective outer portions of the scrolls to provide a higher degree of wear resistance in this region. The outer portion of the scrolls, between which the outer portion 30f of the channel seal 10f is positioned, is a portion of the scrolls falling outside each respective spiral wall. The outer portion 30f therefore functions as a bearing area. Figure 9 illustrates a cross-sectional view of a channel seal 10g according to a seventh embodiment of the present invention. The channel seal 10g is similar to the channel seals 1 Oe and 10f, of Figures 6-8, in that the wear surface of the channel seal 10g has a first portion 24g and a second portion 26g. The first portion 24g is the textured portion of the wear surface, provided by a pattern of first and second ridges. The cross-sectional view is taken through a plane perpendicular to the lengthwise direction of the first ridges 14g (second ridges not shown) formed on the first portion 24g of the wear surface. The second portion 26g of the wear surface is smoother than the first portion 24g and extends around the periphery of the first portion 24g. The second portion 26g of the wear surface is axially offset below the tip 15g of each first ridge 14g in the same manner as previously described.
[0085] The channel seal 10g has a base portion 32g on which the first portion 24g of the wear surface is disposed. In other words, the channel seal 10g has a base portion 32g on which the textured portion of the wear surface is disposed. The base portion 32g is formed from a harder material than the first portion 24g. In other words, the base portion 32g is formed from a harder material than the textured portion and thus has a higher wear resistance.The first portion 24g does not extend across the entirety of the surface of the base portion 32g, As such, a portion of the surface of the base portion 32g that extends around the periphery of the first portion 24g directly forms the second portion 26g of the wear surface. The wear resistance of the second portion 26g is therefore significantly higher than that of the first portion 24g, by virtue of the smoother wear surface and harder material. This further improves the function of the second portion 26g as a bearing area.
[0086] Further, the channel seal 10g can be described as having an inner portion comprising the first portion 24g, ortextured portion, of the wear surface and an outer portion comprising the second portion 26g of the wear surface.
[0087] Figure 10 illustrates a cross-sectional view of a channel seal 10h according to an eighth embodiment of the present invention. The channel seal 10h is similar to the channel seal 10g, of Figure 9, but the entirety of the wear surface of the channel seal 10h is textured. The texture is provided by a pattern of first and second ridges. The cross-sectional view is taken through a plane perpendicular to the lengthwise direction of the plurality of first ridges 14h (plurality of second ridges not shown). The channel seal 10h has a base portion 32h on which the textured portion of the wear surface is disposed. The base portion 32h is formed from a harder material than the textured portion and thus has a higher wear resistance.
[0088] In this particular embodiment, the first ridges 14h protrude directly from the surface of the base portion 32h. In other words, the foot of each ridge 14h is in the same plane as the surface of the base portion 32h. The same applies to the second ridges (not shown). It should be appreciated however that the first and second ridges need not protrude directly from the surface of the base portion 32h, and as such, the foot of each first and second ridge need not be in the same plane as the surface of the base portion 32h.
[0089] In use, the textured portion of the wear surface, i.e. the first and second ridges, are initially worn away until eventually the surface of the base portion 32h is exposed. The initial wear rate of the channel seal 10h is therefore relatively high, due to the textured surface and softer material, as previous described. The bedding-in time is therefore reduced, compared to conventional channel seals. Furthermore, due to thebase portion 32h being formed from a harder material, the wear life of the channel seal 10h is significantly increased after the textured portion wears away.
[0090] Although several embodiments of the invention have been described in detail with reference to Figures 1 to 10, it should be appreciated that the invention is not limited to these precise embodiments and that various modifications may be made by the skilled person without departing from the scope of the invention as claimed herein. For example, the embodiment of Figure 4 provides a scroll pump 100 with two channel seals 10a according to the present invention. It should be appreciated however, that one or both of the channel seals may be a channel seal according to an embodiment of the present invention. In other words, one of the channel seals may be a conventional channel seal. Alternatively, it should also be appreciated that the scroll pump 100 may comprise only one channel seal 10a arranged within only one of the first or second spiral channels. As previously noted, it should also be appreciated that any of the channel seals 10a-h described herein may be applied to the scroll pump 100 of Figure 4. Furthermore, the ridges depicted in Figures 3a-c are shown as being formed integrally with the base portion, however the ridges may alternatively be overmoulded or formed separately to the base portion, to have a structure similar to those illustrated in Figures 9 and 10, for example. The channels seals 10a-h described herein each comprise a textured portion provided by a pattern of first and second ridges, however it should be appreciated that the textured portion may alternatively be formed by a plurality of protrusions taking an alternative geometry, for example, pillars and / or depositions, as previously described herein.REFERENCE NUMERALS
[0091] 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h channel seal
[0092] 12a wear surface
[0093] 14a, 14b, 14c, 14d, 14e, 14f, 14g, 14h first set of parallel ridges (first ridges) 15b, 15c, 15d, 15e, 15f, 15g, 15h tip
[0094] 16a second set of parallel ridges (second ridges)
[0095] 18a pocket
[0096] 20a, 20b, 20c, 20d, 32g, 32h base portion
[0097] 22b, 22c, 22d surface of base portion
[0098] 24e, 24f, 24g first portion
[0099] 26e, 26f, 26g second portion
[0100] 28f inner portion
[0101] 30f outer portion
[0102] 100 scroll pump
[0103] 110 housing
[0104] 120 first scroll
[0105] 122 first base
[0106] 124 first spiral wall
[0107] 130 second scroll
[0108] 132 second base
[0109] 134 second spiral wall150 drive
[0110] D diagonal distance hR first ridge height hB base height
[0111] hS channel seal height W spiral wall width S ridge spacing
[0112] A, A’, A” axial offset
Claims
CLAIMS1. A channel seal for a scroll pump, the channel seal comprising:a wear surface which is subject to wear during operation of the scroll pump, wherein at least a portion of the wear surface is textured.
2. A channel seal according to claim 1, wherein the textured portion of the wear surface comprises a plurality of protrusions.
3. A channel seal according to claim 2, wherein the plurality of protrusions is a repeating pattern of protrusions.
4. A channel seal according to claim 2 or 3, wherein the plurality of protrusions is a pattern of ridges.
5. A channel seal according to claim 4, wherein the pattern of ridges comprises at least a first set of parallel ridges extending in a first direction and a second set of parallel ridges extending in a second direction at an angle to the first direction.
6. A channel seal according to any of claims 2 to 5, wherein the height of each protrusion ranges from 20 to 500 microns, preferably from 20 to 100 microns.
7. A channel seal according to any of claims 2 to 6, wherein each protrusion narrows in a direction towards a tip of said protrusion.
8. A channel seal according to any preceding claim, wherein the wear surface comprises a first portion and a second portion, wherein the first portion of the wear surface is the textured portion and the second portion of the wear surface is smoother than the first portion.
9. A channel seal according to claim 8, comprising an inner portion and an outer portion extending around the periphery of the inner portion, wherein the inner portion comprises the first portion of the wear surface and the outer portion comprises the second portion of the wear surface.
10. A channel seal according to claim 9, wherein the outer portion is formed from a harder material than the inner portion.
11. A channel seal according to any of claims 1 to 8, comprising a base portion on which the textured portion of the wear surface is disposed, wherein the base portion is formed from a harder material than the textured portion.
12. A scroll pump comprising:a first scroll and a second scroll intermeshing with the first scroll, each of the scrolls comprising a base and a spiral wall defining a spiral channel;a drive for effecting relative orbiting motion between the scrolls; and the channel seal of any preceding claim arranged within the spiral channel of one of the scrolls for engaging the spiral wall of the other scroll.
13. A scroll pump according to claim 12 when depending on claim 2, wherein the maximum distance between adjacent protrusions is less than the width of the spiral wall engaging the channel seal.
14. A scroll pump according to claims 12 or 13, comprising a further said channel seal arranged within the spiral channel of the other scroll for engaging the spiral wall of said one of the scrolls.