Multi-inlet cyclone

Abstract

A surface cleaning apparatus comprising a cyclone positioned in an air flow path. The cyclone has a cyclone chamber with a thin walled porous outlet member.

Claims

1. A surface cleaning apparatus comprising: (a) an air flow path extending from a dirty air inlet to a clean air outlet; (b) a cyclone positioned in the air flow path, the cyclone having an interior volume defining a cyclone chamber having a diameter of 0.5-2.5 inches, the cyclone comprising a cyclone chamber air inlet, a cyclone chamber air outlet at a cyclone chamber outlet end, a centrally positioned cyclone axis of rotation, a cyclone chamber second end axially spaced from the cyclone chamber outlet end and a cyclone chamber sidewall extending between the cyclone chamber outlet end and the cyclone chamber second end; and, (c) a suction motor positioned in the air flow path upstream of the clean air outlet, the suction motor has a motor axis of rotation, wherein the cyclone chamber air outlet comprises a vortex finder comprising a porous metal screen, the vortex finder has an air outlet and a longitudinal vortex finder axis that extends in a direction of flow through the air outlet of the vortex finder, the porous metal screen consists of a chemical etched or laser cut continuous metal sheet that has a plurality of openings formed through the continuous metal sheet that are 0.005 to 0.04 inches in length and the openings are spaced apart from each other by 0.0005-0.06 inches, and wherein the vortex finder is contained within the cyclone chamber, and wherein the cyclone axis of rotation, the motor axis of rotation and the longitudinal vortex finder axis extend in a common direction.

2. The surface cleaning apparatus of claim 1 wherein the porous metal screen has a thickness of 0.002 to 0.08 inches.

3. The surface cleaning apparatus of claim 1 wherein the openings are spaced apart from each other by 0.002-0.01 inches.

4. The surface cleaning apparatus of claim 1 wherein the openings are spaced apart from each other by 0.001-0.02 inches.

5. The surface cleaning apparatus of claim 1 wherein the vortex finder has a diameter of about 1 inch.

6. A surface cleaning apparatus comprising: (a) an air flow path extending from a dirty air inlet to a clean air outlet; (b) a cyclone positioned in the air flow path, the cyclone having an interior volume defining a cyclone chamber, the cyclone comprising a cyclone chamber air inlet, a cyclone chamber air outlet at a cyclone chamber outlet end, a cyclone axis of rotation, a cyclone chamber second end axially spaced from the cyclone chamber outlet end and a cyclone chamber sidewall extending between the cyclone chamber outlet end and the cyclone chamber second end; and, (c) a suction motor positioned in the air flow path upstream of the clean air outlet, the suction motor has a motor axis of rotation, wherein the cyclone chamber air outlet comprises a vortex finder comprising a screen that comprises a chemical etched or laser cut continuous metal sheet having a plurality of openings, the continuous metal sheet has a thickness of 0.002 to 0.08 inches, the vortex finder has an air outlet and a longitudinal vortex finder axis that extends in a direction of flow through the air outlet of the vortex finder, and wherein the vortex finder is located within the cyclone chamber, and wherein the cyclone axis of rotation, the motor axis of rotation and the longitudinal vortex finder axis extend in a common direction.

7. The surface cleaning apparatus of claim 6 wherein the openings are 0.001 to 0.02 inches in length.

8. The surface cleaning apparatus of claim 6 wherein the continuous metal sheet has a thickness of 0.005 to 0.04 inches.

9. The surface cleaning apparatus of claim 6 wherein the openings are spaced apart from each other by 0.0005-0.06 inches.

10. The surface cleaning apparatus of claim 6 wherein the openings are 0.002 to 0.01 inches in length, the continuous metal sheet has a thickness of 0.01 to 0.02 and the openings are spaced apart from each other by 0.002 to 0.01 inches.

11. The surface cleaning apparatus of claim 6 wherein the cyclone chamber has a diameter of 0.5-2.5 inches.

12. The surface cleaning apparatus of claim 11 wherein the vortex finder has a diameter of about 1 inch.

13. The surface cleaning apparatus of claim 6 wherein the vortex finder has a diameter of about 1 inch.

14. The surface cleaning apparatus of claim 6 wherein the openings are 0.0005 to 0.06 inches in length and the openings are spaced apart from each other by 0.0005-0.06 inches.

15. A surface cleaning apparatus comprising: (d) an air flow path extending from a dirty air inlet to a clean air outlet, the dirty air inlet is provided at a first end of an air inlet conduit; (e) a cyclone positioned in the air flow path, the cyclone having an interior volume defining a cyclone chamber, the cyclone comprising a cyclone chamber air inlet, a cyclone chamber air outlet at a cyclone chamber outlet end, a cyclone axis of rotation, a cyclone chamber second end axially spaced from the cyclone chamber outlet end and a cyclone chamber sidewall extending between the cyclone chamber outlet end and the cyclone chamber second end; and, (f) a suction motor positioned in the air flow path upstream of the clean air outlet, the suction motor has a motor axis of rotation, wherein the cyclone chamber air outlet comprises a vortex finder comprising a porous metal screen, the porous metal screen comprising a chemical etched or laser cut continuous metal substrate that has a plurality of openings formed through the continuous metal substrate, the vortex finder has an air outlet and a longitudinal vortex finder axis that extends in a direction of flow through the air outlet of the vortex finder, and wherein the cyclone axis of rotation, the motor axis of rotation and the longitudinal vortex finder axis extend in a common direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a better understanding of the described embodiments and to show more clearly how they may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:

(2) FIG. 1 is a top perspective view of a surface cleaning apparatus, according to an embodiment;

(3) FIG. 2 is a perspective cross sectional view of the surface cleaning apparatus of FIG. 1, taken along line 2-2 of FIG. 1;

(4) FIG. 3 is a perspective cross sectional view of the cyclone of the surface cleaning apparatus of FIG. 1, taken along line 2-2 of FIG. 1, schematically showing the airflow therethrough;

(5) FIG. 4 is the perspective cross sectional view of FIG. 3 containing additional reference numbers;

(6) FIG. 5 is a perspective exploded cross sectional view of the cyclone of the surface cleaning apparatus of FIG. 1, taken along line 2-2 of FIG. 1;

(7) FIG. 6 is a top perspective cross sectional view of a cyclone, according to an embodiment;

(8) FIG. 7 is a perspective view of a porous screen of the cyclone of FIG. 6;

(9) FIG. 8 is a top perspective cross sectional view of a cyclone, according to an embodiment;

(10) FIG. 9 is a perspective view of a porous screen of the cyclone of FIG. 8;

(11) FIG. 10 is a perspective view of the inside of a cyclone chamber inlet body of the surface cleaning apparatus of FIG. 1;

(12) FIG. 11 is a perspective view of a sheet or blank which may be formed into the cyclone chamber inlet body of FIG. 10; and,

(13) FIG. 12 is a cross sectional side elevation view of a compression system, according to an embodiment.

(14) The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the teaching of the present specification and are not intended to limit the scope of what is taught in any way.

DESCRIPTION OF EXAMPLE EMBODIMENTS

(15) Various apparatuses, methods and compositions are described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover apparatuses and methods that differ from those described below. The claimed inventions are not limited to apparatuses, methods and compositions having all of the features of any one apparatus, method or composition described below or to features common to multiple or all of the apparatuses, methods or compositions described below. It is possible that an apparatus, method or composition described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus, method or composition described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicant(s), inventor(s) and/or owner(s) do not intend to abandon, disclaim, or dedicate to the public any such invention by its disclosure in this document.

(16) The terms “an embodiment,” “embodiment,” “embodiments,” “the embodiment,” “the embodiments,” “one or more embodiments,” “some embodiments,” and “one embodiment” mean “one or more (but not all) embodiments of the present invention(s),” unless expressly specified otherwise.

(17) The terms “including,” “comprising” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. A listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an” and “the” mean “one or more,” unless expressly specified otherwise.

(18) As used herein and in the claims, two or more parts are said to be “coupled”, “connected”, “attached”, or “fastened” where the parts are joined or operate together either directly or indirectly (i.e., through one or more intermediate parts), so long as a link occurs. As used herein and in the claims, two or more parts are said to be “directly coupled”, “directly connected”, “directly attached”, or “directly fastened” where the parts are connected in physical contact with each other. None of the terms “coupled”, “connected”, “attached”, and “fastened” distinguish the manner in which two or more parts are joined together.

(19) Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the example embodiments described herein. Also, the description is not to be considered as limiting the scope of the example embodiments described herein.

(20) As used herein, the wording “and/or” is intended to represent an inclusive-or. That is, “X and/or Y” is intended to mean X or Y or both, for example. As a further example, “X, Y, and/or Z” is intended to mean X or Y or Z or any combination thereof.

(21) General Description of a Surface Cleaning Apparatus

(22) Referring to FIGS. 1 and 2, an exemplary embodiment of a surface cleaning apparatus is shown generally as 100. Surface cleaning apparatus 100 includes an apparatus body 102 having a housing 104 and a handle 106. An air treatment member 110 is connected to the apparatus body 102.

(23) In the embodiment illustrated, the surface cleaning apparatus 100 is a hand-held vacuum cleaner, which is commonly referred to as a “hand vacuum cleaner” or a “handvac”. As used herein, a hand-held vacuum cleaner or hand vacuum cleaner or handvac is a vacuum cleaner that can be operated generally one-handedly to clean a surface while its weight is held by the same one hand. This is contrasted with upright and canister vacuum cleaners, the weight of which is supported by a surface (e.g. floor below) during use. Optionally, surface cleaning apparatus 100 could be, for example, an upright vacuum cleaner, a canister vacuum cleaner, a stick vac, a wet-dry vacuum cleaner and the like.

(24) Surface cleaning apparatus 100 has an air flow path extending from a dirty air inlet 112 to a clean air outlet 114 (FIG. 2). Surface cleaning apparatus 100 also has a front end 118, a rear end 120, an upper end or top 122, and a lower end or bottom 124. Optionally, as exemplified, dirty air inlet 112 may be at an upper portion of the front end 118 and clean air outlet 114 may be at a rearward portion of the lower end 124. In other embodiments, dirty air inlet and clean air outlet 112, 114 may be provided in different locations.

(25) A suction motor 126 (FIG. 2) is provided to generate vacuum suction through the air flow path, and is positioned within a motor housing 128 upstream of clean air outlet 114. In the illustrated embodiment, the suction motor 126 is positioned downstream from the air treatment member 110, and an optional pre-motor filter, although in alternative embodiments it may be positioned upstream of the air treatment member 110.

(26) Air treatment member 110 is configured to remove particles of dirt and other debris from the air flow and/or otherwise treat the air flow. The air treatment member may comprise one or more cyclonic cleaning stages, each of which may comprise a single cyclone or a plurality of cyclones in parallel. In the illustrated example, air treatment member 110 comprises a cyclone assembly 130 which has a first cyclonic cleaning stage 170 and a second, downstream, cyclonic cleaning stage 172. Each cyclonic cleaning stage 170, 172 may comprise a single cyclone (or cyclone chamber) or a plurality of cyclones (or cyclone chambers) in parallel. As exemplified in FIGS. 2 and 3, the first cyclonic cleaning stage 170 comprises a single cyclone chamber 174 and second cyclonic cleaning stage 172 comprises a single cyclone chamber 176.

(27) The first and second cyclonic cleaning stages 170, 172 may have a common dirt collection region. Alternately, each cyclonic cleaning stage 170, 172 may have one or more dirt collection regions. While in some embodiments the dirt collection region may be part of cyclone chamber, as exemplified cyclone chamber 174 has a dirt collection chamber 178 which is external to the cyclone chamber 174. Dirt collection chamber 178 is in communication with cyclone chamber 174 via one or more dirt outlets 180. As exemplified, cyclone chamber 176 has a dirt collection chamber 182 which is external to the cyclone chamber 176. Dirt collection chamber 182 is in communication with cyclone chamber 176 via one or more dirt outlets 184 (See FIG. 5).

(28) A cyclone chamber may have one or more air inlets and one or more air outlets. The air inlet(s) and air outlet(s) may be at the same end of a cyclone chamber or opposed ends.

(29) As exemplified in FIGS. 2-5, cyclone chamber 174 has a centrally positioned axis of rotation 148 and first and second axially opposed ends 134, 136. A single cyclonic air inlet 138 is provided at first end 134, which may also be referred to as a front end or an inlet end of the cyclone 174. A single air outlet 140 is provided at second end 136, which may also be referred to as a rear end or an outlet end of the cyclone 174. Accordingly, cyclone 174 may be referred to as a uniflow cyclone since the air enters one end of the cyclone chamber and exits via the opposed end of the cyclone chamber. The air flow is shown schematically by arrows 142.

(30) As exemplified in FIGS. 2-5, cyclone chamber 176 has a centrally positioned axis of rotation, which is co-axial with the cyclone axis of rotation of cyclone 174 and is therefore also denoted by reference numeral 148. It will be appreciated that the cyclone axes of rotation need not be co-axial and need not be parallel. Cyclone chamber 176 has first and second axially opposed ends 220, 222. A plurality of cyclonic air inlets 226 are provided at first end 220 of cyclone chamber 176, which may also be referred to as a front end or an inlet end of the cyclone 176. A single air outlet 228 is also provided at second end 222, which may be referred to as a rear end or an outlet end of cyclone 176. Inlets 226 are positioned immediately rearward of second end 186 of the upstream cyclone chamber 174. The second end 186 of cyclone chamber 174 is spaced from the outlet end 136 of cyclone chamber 174.

(31) Thin Walled Air Flow Passage

(32) Portions of a cyclone may be made of a thin walled material. Each thin walled portion may be a separately manufactured part that is then secured to another part. For example, a thin walled part may be prepared by bending or stamping a die cut blank or substrate and then securing the thin walled part to a part which may be produced by molding.

(33) An advantage of this design is that smaller cyclones, which would have smaller sized air inlets, may be prepared while enabling the cross-sectional area in a direction transverse to the flow direction to be enlarged.

(34) A cyclone, such as for example a hand vacuum cleaner, may have a cyclone having a diameter of between 0.5 inches and 4 inches, 0.5 and 2.5 inches, or 0.5 and 2 inches or 0.5 and 1.5 inches. Portions of the walls that define one or both sides of an air flow passage for the cyclone may have a wall thickness (in a direction transverse to the direction of air flow through the air flow passage) of 0.001 to 0.06 inches, 0.002 to 0.03 inches, or 0.005 to 0.015 inches. The air flow passage having the thinner walls may be part or all of the air flow passage extending to the cyclone air inlets and/or the cyclone air outlet (a vortex finder).

(35) Thin wall portions may be formed out of metal or plastic. Plastic is often used to form body portions of vacuums due to its strength profile and cost. Plastic may also be easy and/or cheap to form or shape. However, typically molding processed for vacuum cleaner parts produce parts having a relatively thick wall to provide a vacuum cleaner that is durable.

(36) Accordingly, thin walled portions may be made of metal, such as aluminum or steel, and then may be secured to a molded plastic part. Using metal may enable the production of a part having a thin wall that is rigid and will withstand wear.

(37) Alternately, thin walled parts may be made from plastic by alternate manufacturing methods. For example, one or more thin wall portions may be formed of sheet plastic or machined plastic. Wall portions may be formed by bending or machining a substrate into shape, such as by heat bending a plastic sheet.

(38) Annular Flow Region

(39) In accordance with one aspect, which may be used by itself or with any other aspect set out herein, a cyclone may have two or more inlets and a flow region or header may be provided to distribute the air amongst the plurality of cyclone air inlets. For example, as exemplified in FIG. 4, a header or flow region 194 is provided around the second stage cyclone air inlets 226. As exemplified, cyclone 170 has an outlet 140 at an outlet end 136 and a second end 186 spaced from outlet end 136. Cyclone assembly 130 includes an outer wall 188 extending between the cyclone chamber outlet end 136 and the cyclone chamber second end 186. Air inlets 226 are provided at the cyclone chamber outlet end 136 of cyclone chamber 174. The plurality of cyclone air inlets 226 is spaced from an inner surface 192 of the cyclone chamber sidewall 188 and a flow region 194 extends around the plurality of cyclone air inlets 226. Accordingly, air exiting cyclone chamber 174 passes through outlet 140 and enters flow region 194. The air then passes through second stage air inlets 226.

(40) Radial flow region 194 extends between inner surface 192 of the cyclone chamber sidewall 188 and sidewall portions 158, and has a radial thickness R (see FIG. 2). Optionally, the cross-sectional area of the flow region 194 in a direction transverse to the direction of flow entering the flow region (which may be considered the radial direction or a direction transverse to the cyclone axis of rotation 148) is at least as large as the cross-sectional area of cyclone air outlet 140 in a direction transverse to the direction of flow through cyclone air outlet 140, or it may be 10%, 15%, 20%, 25% or 50% larger.

(41) Increasing the diameter of sidewall 188 would increase the size of the cross-sectional area of the flow region 194 in the radial direction, but it would also increase the size of the hand vacuum cleaner. If the hand vacuum cleaner is to be miniaturized, then it is advantageous to increase the cross-sectional area of the flow region 194 in the radial direction without increasing the size of any components.

(42) It will be appreciated that the cross-sectional area of the flow region 194 in the radial direction may be increased by one or both of sidewall 188 and sidewall portions 158 having a smaller thickness in the radial direction. If the cross-sectional area of the flow region 194 in the radial direction is small, as in the case of a cyclone having a diameter of between 0.5 inches and 4 inches, 0.5 and 2.5 inches, or 0.5 and 2 inches or 0.5 and 1.5 inches, then a small reduction in the wall thickness may increase the cross-sectional area of the flow region 194 in the radial direction by 10%, 15%, 20%, 25% 50% or more.

(43) It will be appreciated that, for small diameter cyclones, the cyclone may be manufactured by different techniques. As exemplified in FIGS. 2-9, cyclone 176 comprises a cyclone main body 150 and a chamber inlet body 152.

(44) As exemplified in FIG. 10, cyclone chamber inlet body 152 has an inlet end wall 156 and a plurality of sidewall portions 158 angularly spaced apart around at least a portion of, and optionally all of, a radial outer perimeter 160 of end wall 156. Cyclone chamber inlet body is of a thin wall construction and may have a thickness T of 0.001 to 0.06 inches, 0.002 to 0.03 inches, or 0.005 to 0.015 inches. Reducing thickness T may therefore provide a large increase in the cross-sectional area of the flow region 194 in the radial direction.

(45) Chamber inlet body 152 may be separately manufactured and then secured (releasably or permanently secured) to cyclone main body 150 to form cyclone 176. For example, chamber inlet body 152 may be secured to a support housing provided in surface cleaning apparatus 100 or it may be secured to cyclone main body 150.

(46) As exemplified, chamber inlet body 152 and cyclone main body 150 are securable in an assembled configuration. Cyclone chamber 176 is formed between chamber inlet body 152 at a cyclone chamber inlet end 220 and an opposed end wall 154 formed by cyclone main body 150. Opposed end wall 154 is axially spaced apart from the cyclone chamber inlet end 220 and is at outlet end or opposed end 222. A main body sidewall 232 forms a radial outer wall of cyclone chamber 176. Main body sidewall 232 extends between the cyclone chamber inlet body 152 and the opposed end wall 154.

(47) As exemplified in FIG. 5, main body 150 may comprise a plurality of portions 150c and 150d (FIG. 5) that can also be manufactured separately and then secured (releasably or permanently secured) to form a main body 150 of cyclone assembly 130. Cyclone body portion 150c comprises the inlet end of the exemplified cyclone. Chamber inlet body 152 is securable to cyclone body portion 150c so as to form the cyclone inlets of the cyclone 176. Cyclone end portion 150d forms the outlet end of the cyclone 176. Alternately, it will be appreciated that cyclone body portion 150c and cyclone end portion 150d may be manufactured as a unitary body (e.g., molded as a single component).

(48) Similarly, the first stage cyclone chamber 174 may also be formed from 2 or more components. As exemplified, first stage inlet portion 150a and first stage cyclone main body portion 150b together define the first stage cyclone 174. Alternately, portions 150a and 150b may be manufactured as a unitary body.

(49) Portions 150b and 150c together with chamber inlet body 152 define the header or flow region 194 around the second stage cyclone air inlets 226. Releasable securing of two or more of portions 150a, 15b, 15c, 150d together may allow a user to access an interior of cyclone assembly 130, such as to empty a dirt chamber.

(50) Cyclone chamber inlet body 152 may be mounted to the cyclone main body sidewall 232 by any means. As exemplified, main body sidewall 232 has a terminal end 234 spaced from the opposed end wall 154.

(51) The plurality of cyclonic air inlets 226 are each formed between two adjacent sidewall portions 158. The sidewall portions 158 extend towards the opposed end wall 154 from the cyclone chamber inlet end wall 156. The plurality of sidewall portions 158 each have a terminal end 236 spaced from the cyclone chamber inlet end wall 156. The terminal ends 236 of the sidewall portions 158 mate with the terminal end 234 of the main body sidewall 232. For example, as exemplified, terminal end 234 of the main body sidewall 232 has recesses 238 in which the terminal end 236 of the sidewall portions 158 are received. They may be secured therein by welding, an adhesive or a friction fit.

(52) Optionally, the cross-sectional area defined by cyclonic air inlets 226 in a direction transverse to the direction of flow passing between sidewall portions 58 is at least as large as the cross-sectional area of cyclone air outlet 140 in a direction transverse to the direction of flow through cyclone air outlet 140, or it may be 10%, 15%, 20% or 25% larger. Alternately, or in addition, the cross-sectional area defined by cyclonic air inlets 226 may be the same as the cross-sectional area of the flow region 194 in the radial direction±20%.

(53) Cyclone Air Outlet Conduit

(54) Alternately, or in addition to having a thin walled cyclone chamber inlet body 152, the cyclone air outlet (or vortex finder) may also have a thin walled construction and may also be separately manufactured.

(55) Accordingly, as exemplified, cyclone chamber 176 has a vortex finder 190. Vortex finder 190 may also be separately manufactured and then mounted (releasably or permanently mounted) in cyclone assembly 130. It will be appreciated that the vortex finder may be of various designs that are known.

(56) In a small diameter cyclone, as discussed herein, the vortex finder may have an inner flow diameter of, e.g., about 1 inch (20-25 mm). Increasing the diameter of outlet conduit 140 would increase the cross-sectional flow area through the outlet conduit. However, it would reduce the radial thickness of the cyclonic flow region between the outlet conduit and cyclone sidewall 232. However, by reducing the radial thickness of outlet conduit 140 the cross-sectional flow area through the outlet conduit may be increased without decreasing the radial thickness of the cyclonic flow region between the outlet conduit 140 and cyclone sidewall 232.

(57) For example, if the internal diameter of a vortex finder is increased from, e.g., 21 mm to, e.g., 24 mm, then the cross-sectional flow are in the direction of flow through the vortex finder is increased from 346.4 mm.sup.2 to 452.4 mm.sup.2. Therefore, increasing the diameter of a vortex finder by 3 mm produces a 31% increase in the cross-sectional flow areas in the direction of flow through the vortex finder. Accordingly, small changes in the cross-sectional flow area can produce a significant change in the back-pressure.

(58) Screen

(59) Alternately, or in addition to having a thin walled cyclone chamber inlet body 152 and/or a thin walled cyclone outlet conduit 140, a screen that is provided at the cyclone outlet may also have a thin walled construction and may also be separately manufactured.

(60) In order to inhibit hair and large particulate matter passing through a cyclone air outlet, such as in a first stage cyclone, a vortex finder may comprise a porous section or have a screen overlying an outlet conduit. The porous section or screen may have a wall thickness 204 of 0.001 to 0.06 inches, 0.002 to 0.03 inches, or 0.005 to 0.015 inches (see FIG. 6).

(61) As exemplified in FIGS. 6-9, vortex finder 242 comprises a porous screen 196 comprising a substrate 198 having a plurality of openings 200. The screen defines a flow area through which air passes as it exits the cyclone chamber 174 to travel to the second stage cyclone camber 176.

(62) Increasing the size of the screen will increase the flow area through which air passes as it exits the cyclone chamber 174. However, this will reduce the volume in the cyclone chamber for cyclonic flow. Increasing the number of openings in the screen without reducing the size of the openings and without increasing the size of the screen will increase the flow area through which air passes as it exits the cyclone chamber 174.

(63) The screen may have closely spaced and/or large openings to increase the flow area. For example, openings may be 0.0005 to 0.06 inches, 0.001 to 0.02 inches, or 0.002 to 0.01 inches in length 202. Openings may be spaced from each other by a spacing 206 of 0.0005 inches to 0.06 inches, 0.001 inches to 0.02 inches or 0.002 to 0.01 inches. Increasing the number of openings 200 will increase the flow area through which air passes as it exits the cyclone chamber 174. The number of openings may be increased by providing the openings closer together, without increasing the size of the screen.

(64) Manufacturing Processes

(65) In accordance with this aspect, a thin walled part may be prepared by bending or forming a part from a continuous planar substrate. Accordingly, a continuous substrate, that may be plastic or metal, may be prepared in a desired shape (e.g., by being stamped or die cut) and then formed (e.g., bent) to form a part. Such a technique may be used to form cyclone chamber inlet body 152.

(66) As exemplified in FIGS. 10 and 11, cyclone chamber inlet end wall 156 and the sidewall portions 158 are integrally formed. According to this aspect, sidewall portions 158 may be mechanically shaped to extend generally axially away from the cyclone chamber inlet end wall 156.

(67) For example, cyclone chamber inlet body 152 may be formed from a generally planar sheet 164 having a plurality of flanges 166 extending outwardly from the cyclone chamber inlet end wall 156. Sidewall portions 158 may be formed by bending the flanges 166 to extend at an angle 168 to a plane in which the cyclone chamber inlet end wall 152 extends. For example, a metal plate 164 may be metal stamped to form sidewall portions 158, or a plastic sheet 164 may be shaped using a thermomechanical process such as a heat bending process to form sidewall portions 158. A plastic sheet 164 may, in some embodiments, be molded with bend lines at the base of each flange 166, or may otherwise incorporate structure to facilitate bending.

(68) Flanges 166 may be bent to an angle 168 that maximizes stability and durability, such as an angle of 90°. Sidewall portions 158 may be arranged so that a projection 169 of a width of an opening 226 on an internal surface of a sidewall 158 is spaced from each axial edge 171 of the sidewall 158.

(69) Alternately, or in addition, according to this aspect a screen 198 may be formed by chemical etching or laser cutting of a continuous substrate.

(70) Alternately, or in addition, according to this aspect a screen may be formed from a woven mesh by compression.

(71) As exemplified in FIG. 12, a porous screen 198 may be produced by producing a woven mesh material and subjecting the woven mesh material to compression whereby the thickness of the woven mesh material is reduced. For example, the woven mesh material may be produced from metal strands. Subjecting the woven mesh material to compression may be done by stamping the woven mesh material or compressing the woven mesh material between opposed rollers.

(72) FIG. 12 schematically depicts a method 218 of producing a porous screen. In some embodiments a woven mesh material 208 is produced of metal strands 210 and is then compressed between opposed rollers 212 to produce porous screen 206. Opposed rollers 212 may compress the metal strands 210 together and may flatten metal strands 210. Accordingly, a thinner walled screen may be produced.

(73) The woven mesh material 208 may be produced with a looser weave, which will have a larger spacing or opening 214 between strands 210 than a woven mesh that is not to be compressed. Compression flattens and/or otherwise shifts or reshapes strands 210 resulting in the openings in the screen becoming smaller. Accordingly, a larger spacing 214 is needed before compression to result a desired size 202 and spacing 206 of openings 200 in a compressed screen 198.

(74) While the above description describes features of example embodiments, it will be appreciated that some features and/or functions of the described embodiments are susceptible to modification without departing from the spirit and principles of operation of the described embodiments. For example, the various characteristics which are described by means of the represented embodiments or examples may be selectively combined with each other. Accordingly, what has been described above is intended to be illustrative of the claimed concept and non-limiting. It will be understood by persons skilled in the art that other variants and modifications may be made without departing from the scope of the invention as defined in the claims appended hereto. The scope of the claims should not be limited by the preferred embodiments and examples, but should be given the broadest interpretation consistent with the description as a whole.