US20090313958A1 - Cyclonic separating apparatus - Google Patents

Abstract

A cyclonic separating apparatus for separating particles from a dirt-laden airflow includes a cyclone for separating and collecting dirt and dust from the dirt-laden airflow. The cyclone has an air inlet, an air outlet, a longitudinal axis and a wall. The wall includes a first portion and a second portion spaced farther from the longitudinal axis than the first portion, the first and second portions being spaced along the longitudinal axis. The cyclone also includes at least one lip extending from the first portion of the wall into a portion of the cyclone surrounded by the second portion of the wall. By providing a cyclone with a wall having two portions of different sizes and a lip extending from the portion with the smaller size into the portion with the larger size, the risk of blockages due to re-entrainment and movement of dirt and dust within the cyclonic separating apparatus is reduced.

Description

REFERENCE TO RELATED APPLICATIONS
• This application is a national stage application under 35 USC 371 of International Application No. PCT/GB2007/002525, filed Jul. 6, 2007, which claims the priority of United Kingdom Application No. 0614237.6, filed Jul. 18, 2006, the contents of which prior applications are incorporated herein by reference.
FIELD OF THE INVENTION
• The invention relates to cyclonic separating apparatus particularly, but not exclusively, for a vacuum cleaner. More particularly, the invention relates to cyclonic separating apparatus for a hand-held vacuum cleaner.
BACKGROUND OF THE INVENTION
• Cyclonic separating apparatus is known from, for example, EP 0 042 723. This document discloses a vacuum cleaner which separates particles from an airflow using two reverse flow cyclones. The cyclones comprise a first, low-efficiency cyclone and a second, high-efficiency cyclone downstream of the first cyclone. Dirt- and dust-laden air enters through an inlet in the first cyclone and follows a downward helical path around the interior of the first cyclone. Centrifugal forces act on the entrained dirt and dust to separate it from the airflow. When separated from the airflow, the dirt and dust collects at the base of the first cyclone. Upon reaching the base of the first cyclone, the airflow reverses direction. The partially-cleaned airflow moves back up the first cyclone and exits the first cyclone through an outlet. It is usual to provide a so-called shroud around the outlet from the first cyclone. The shroud comprises a wall with a large number of through-holes through which the airflow passes in order to reach the second cyclone. The air then enters the second cyclone and follows a downward helical path inside the second cyclone. Smaller particles are separated from the airflow in a similar fashion to the first cyclone and are deposited in a collector located beneath the second cyclone. The cleaned air then flows back up the interior of the second cyclone and passes sequentially through a pre-motor filter, a motor and a post-motor filter before being exhausted from the vacuum cleaner.
• Occasionally, in this arrangement, some of the dirt and dust which has been separated from the airflow becomes re-entrained in the return airflow. This is undesirable because this dirt and dust may cause blockages in parts of the cyclonic separating apparatus such as the through-holes of the shroud. Blocking the through-holes of the shroud will reduce the efficiency at which the cyclonic separating apparatus operates.
• In order to improve the retention of dirt and dust in the first cyclone upstream of the shroud, it is known to provide the shroud with a lip projecting into the first cyclone. An example of such a lip is shown and described in EP 0 800 359. This lip reduces the risk of the shroud through-holes becoming clogged or blocked.
• However, whilst this solution is useful for cyclonic separating apparatus which is orientated substantially vertically (such as in an upright machine), this arrangement may be less effective for cyclonic separating apparatus which is orientated away from the vertical. Such a situation may arise when, for example, the cyclonic separating apparatus is arranged at an angle to the vertical in a cylinder machine or forms part of a hand-held vacuum cleaner which may be held at an arbitrary angle by a user. In these circumstances, there is a risk that the separated dirt and dust will move towards the outlet of the first cyclone. This is undesirable because the dirt and dust may block the inlet or the through-holes in the shroud.
• It is known to provide an inwardly-extending projection on the wall of a cyclone. EP 0 728 435 and GB 2 363 744 both show an inwardly-projecting annular collar or rib located around the lower part of the inner surface of such a cyclone. In both of these prior art disclosures, it is suggested that these features will help to prevent dirt and dust becoming re-entrained in the partially-cleaned airflow. However, the introduction of elements such as inwardly-projecting ribs or collars on the inner wall of a cyclone may also introduce unwanted effects. For example, these elements may generate turbulence within the cyclone which may disturb the deposited dirt and dust in an undesirable way. Further, the introduction of these elements can reduce the separation efficiency of the cyclone.
SUMMARY OF THE INVENTION
• It is an object of the present invention to provide cyclonic separating apparatus which reduces the risk of re-entrainment of dirt and dust separated from an airflow whilst minimising any detrimental effect on the separation efficiency of the cyclonic separating apparatus. It is a further object to provide cyclonic separating apparatus which minimises the risk of re-entrainment of dirt and dust separated from an airflow when the cyclonic separating apparatus is moved away from a vertical orientation.
• The invention provides cyclonic separating apparatus for separating particles from a dirt- and dust-laden airflow comprising a cyclone for separating and collecting dirt and dust from the dirt- and dust-laden airflow, the cyclone having an air inlet, an air outlet, a longitudinal axis and a wall, the wall comprising a first portion and a second portion spaced further from the longitudinal axis than the first portion, the first and second portions being axially spaced along the longitudinal axis, wherein the cyclone further comprises at least one lip extending from the first portion of the wall into a portion of the cyclone surrounded by the second portion of the wall. By providing a cyclone with a wall having two portions of different sizes and a lip extending from the smaller portion into the larger portion, the risk of blockages due to re-entrainment and movement of dirt and dust within the cyclonic separating apparatus is reduced.
• Preferably, the first portion of the cyclone is cylindrical and has a first radius. More preferably, at least a part of the second portion of the cyclone is cylindrical and has a second radius.
• Preferably, the lip forms a substantially straight extension of the first portion of the wall. This arrangement minimises the protrusion of the lip into the airflow whilst still reducing the risk of re-entrainment of separated dirt and dust within the cyclonic separating apparatus.
• Preferably, the cyclonic separating apparatus comprises at least one further cyclone and a collector which are located downstream of the air outlet, the at least one further cyclone being arranged to deposit separated dirt and dust into the collector. More preferably, the collector has a longitudinal axis, a wall and at least one further lip extending from the wall of the collector into the collector. By providing a lip extending from the wall of the collector, the risk of re-entrainment and migration of fine dirt and dust deposited in the collector can be minimised and thus the risk of the further cyclones becoming blocked is reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
• Embodiments of the invention will now be described with reference to the accompanying drawings, in which:
• FIG. 1 shows a hand-held vacuum cleaner incorporating cyclonic separating apparatus according to a first embodiment of the invention;
• FIG. 2 is a cross section through the cyclonic separating apparatus of the hand-held vacuum cleaner ofFIG. 1 taken along a longitudinal axis thereof;
• FIG. 3 is a lateral cross section through the cyclonic separating apparatus of the hand-held vacuum cleaner ofFIG. 1; and
• FIGS. 4 to 11 are schematic diagrams of alternative embodiments of part of the cyclonic separating apparatus according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
• FIG. 1 shows a hand-heldvacuum cleaner10. The hand-heldvacuum cleaner10 has amain body12 which houses a motor and fan unit (not shown). Themain body12 also includes apower source14 such as a battery. Ahandle16 is provided on themain body12 for manipulating the hand-heldvacuum cleaner10 in use. Cyclonic separatingapparatus100 is attached to themain body12. Aninlet pipe18 extends from a portion of the cyclonic separatingapparatus100 remote from themain body12. Adirty air inlet20 is formed at the distal end of theinlet pipe18. Abrush tool22 is slidably mounted on the distal end of theinlet pipe18. A set ofexhaust vents24 are provided on themain body12 for exhausting air from the hand-heldvacuum cleaner10.
• The cyclonic separatingapparatus100 forming part of the hand-heldvacuum cleaner10 is shown in more detail inFIGS. 2 and 3. Thecyclonic separating apparatus100 comprises acyclone102 which has a longitudinal axis X-X and awall104. Thewall104 comprises afirst portion106 and asecond portion108. Aninlet110 is formed in thewall104 and arranged so that thefirst portion106 of thewall104 is located between theinlet110 and thesecond portion108 of thewall104. Theinlet110 is in communication with thedirty air inlet20 and forms a communication path between theinlet pipe18 and the interior of thecyclone102. Theair inlet110 is arranged tangentially to thecyclone102 so that the incoming air is forced to follow a helical path around the interior of thecyclone102.
• Thefirst portion106 of thewall104 is substantially cylindrical and is in two parts. This is so that the parts can be separated to allow cleaning of the interior of thecyclone102. However, this is not material to the invention. Thesecond portion108 of thewall104 is spaced further from the longitudinal axis X-X than thefirst portion106 of thewall104. Thesecond portion108 of thewall104 includes ashoulder112 and acylindrical part113. Alip114 extends from thefirst portion106 of thewall104 into the space surrounded by thesecond portion108 of thewall104 of thecyclone102. Thelip114 forms a substantially straight extension of thefirst portion106 of thewall104. The function of thelip114 will be described later.
• Abase116 closes one end of thecyclone102. Thebase116 is pivotably mounted on the lower end of thesecond portion108 of thewall104 by means of ahinge118. Thebase116 is retained in a closed position (as shown inFIGS. 1 to 3) by means of acatch120.
• Ashroud121 is located inwardly of thewall104 of thecyclone102. Theshroud121 comprises acylindrical wall122 having a plurality of through-holes123. Theshroud121 surrounds anoutlet124 from thecyclone102. Theoutlet124 provides a communication path between thecyclone102 and afurther cyclone assembly126. Alip128 is provided at the base of theshroud121. Thelip128 has a plurality of through-holes which are designed to allow air to pass through but to capture dirt and dust.
• Thefurther cyclone assembly126 comprises a plurality offurther cyclones130 arranged in parallel. In this embodiment, sixfurther cyclones130 are provided. Eachfurther cyclone130 has a tangentially-arrangedair inlet132 and anair outlet134. Eachair inlet132 andair outlet134 is located at a first end of the respectivefurther cyclone130. Acone opening136 is located at a second end of eachfurther cyclone130. Thecone opening136 of eachfurther cyclone130 is inclined with respect to a longitudinal axis (not shown) of the respectivefurther cyclone130 as can be best seen inFIG. 3. Thecone openings136 of each of thefurther cyclones130 are in communication with apassageway138 defined by awall140 located inwardly of theshroud121.
• Acollector142 is located at the lower end of thepassageway138. Thecollector142 comprises a frustoconicalfirst portion144 and a cylindricalsecond portion146. The interior of thecollector142 is surrounded by thebase116 and the sides of the first andsecond portions144,146 of thecollector142.
• Afurther lip148 extends into the portion of thecollector142 surrounded by the cylindricalsecond portion146. Thefurther lip148 comprises afrustoconical portion148aand acylindrical portion148bwhich extends substantially parallel to the sides of thesecond portion146 of thecollector142. The function of thefurther lip148 will be described later.
• Each of theair outlets134 of thefurther cyclones130 is in communication with aduct150. Theduct150 provides an airflow path from thecyclonic separating apparatus100 into other parts of the hand-heldvacuum cleaner10. Located at the downstream end of theduct150 is apre-motor filter152. Thepre-motor filter152 comprises a porous material such as foam.
• In use, the motor and fan unit draws a flow of dirt-laden air into thedirty air inlet20, through theinlet pipe18 and into thecyclonic separating apparatus100. Dirt-laden air enters thecyclonic separating apparatus100 through theinlet110. Due to the tangential arrangement of theinlet110, the airflow is forced to follow a helical path around the interior of thewall104. Larger dirt and dust particles are separated by cyclonic motion around thewall104. These particles are then collected at thebase116 of thecyclone102. Separation of larger particles will occur in the region of thecyclone102 surrounded by thefirst portion106 of thewall104 and also the portion of thecyclone102 surrounded by thelip114. Separated particles gather in the portion of thecyclone102 surrounded by thesecond portion108 of thewall104.
• The partially-cleaned airflow then flows back up the interior of thecyclone102 and exits thecyclone102 via the through-holes in theshroud121. Once the airflow has passed through theshroud121, it enters theoutlet124 and from there is divided between thetangential inlets132 of each of thefurther cyclones130. Each of thefurther cyclones130 has a diameter smaller than that of thecyclone102. Therefore, thefurther cyclones130 are able to separate smaller particles of dirt and dust from the partially-cleaned airflow than thecyclone102. Separated dirt and dust exits thefurther cyclones130 via thecone openings136. Thereafter, the separated dirt and dust passes down thepassageway138 and into thecollector142. The separated dirt and dust eventually settles at the base of thecollector142.
• Cleaned air then flows back up thefurther cyclones130, exits thefurther cyclones130 through theair outlets134 and enters theduct150. The cleaned air then passes from theduct150 sequentially through thepre-motor filter152, the motor and fan unit, and a post-motor filter before being exhausted from thevacuum cleaner10 through the air vents24.
• It is likely that, in use, the hand-heldvacuum cleaner10 will be held in a variety of orientations. It may even be held upside down in use. When thecyclonic separating apparatus100 is tilted away from the vertical, a large proportion of the separated dirt and dust that may otherwise move towards theinlet110 and theshroud121 is caught in an annular pocket created between thelip114 and thesecond portion108 of thewall104. Further, the presence of the above-described pocket may assist in the creation of stagnation points and eddy-currents within the lower portion of thecyclone102. This may further prevent re-entrainment of separated dirt and dust into the return airflow.
• Regarding thecollector142, a pocket is created between thesecond portion146 of thecollector142 and thefurther lip148. The pocket will prevent a proportion of the separated dirt and dust which may potentially block thecone openings136 or other parts of thefurther cyclones130 from re-entering thepassageway138 when the hand-heldvacuum cleaner10 is tilted away from the vertical.
• Thecyclone102 andcollector142 can be emptied simultaneously by releasing thecatch120 to allow the base116 to pivot about thehinge118 so that the separated dirt and dust can fall away from thecyclonic separating apparatus100.
• Both thelip114 and thefurther lip148 may take different configurations or shapes from those shown in the first embodiment.FIGS. 4 to 11 illustrate schematically eight further alternative configurations of the lip or lips which fall within the scope of the invention. In these illustrations, all detail will be omitted other than the general shape of the lip and adjoining wall portions. These configurations of lip may be applied to either the lip in the cyclone or to the further lip in the collector.
• FIG. 4 shows a second embodiment of the invention. In this embodiment, thecyclonic separating apparatus200 includes alip202 which extends from afirst portion204 of a wall into a region surrounded by asecond portion206 of the wall. Thelip202 has a plurality of through-holes which allow air to pass but block larger particles of dirt and dust. Otherwise, thelip202 is the same as thelip114 described above.
• FIG. 5 shows a third embodiment of the invention. In this embodiment, thecyclonic separating apparatus250 includes alip252 which extends from a frustoconically-shapedfirst portion254 of a wall into a region surrounded by asecond portion256 of the wall. Thesecond portion254 of the wall is partly frustoconical-shaped and partly cylindrical.
• FIG. 6 shows a fourth embodiment of the invention. In this embodiment (which is not shown to scale), the cyclonic separating apparatus300 has a longitudinal axis X′-X′ and includes alip302 which extends from a cylindrically-shapedfirst portion304 of a wall into a region surrounded by asecond portion306 of the wall. Thelip302 extends inwardly from thefirst portion304 of the wall at an angle to the longitudinal axis X′-X′.
• FIG. 7 shows a fifth embodiment of the invention. In this embodiment (which is also not shown to scale), the cyclonic separating apparatus350 has a longitudinal axis X″-X″ and includes alip352 which extends from a cylindrically-shapedfirst portion354 of a wall into a region surrounded by asecond portion356 of the wall. Thelip352 extends outwardly from thefirst portion304 of the wall at an angle to the longitudinal axis X″-X″.
• FIG. 8 shows a sixth embodiment of the invention. In this embodiment, thecyclonic separating apparatus400 includes alip402 which extends from a cylindrically-shapedfirst portion404 of a wall into a region surrounded by asecond portion406 of the wall. Thelip402 comprises two parts—a first part which forms a substantially straight extension of thefirst portion404 of the wall and a second part which forms an inwardly-extending annular part at right angles to the first part.
• FIG. 9 shows a seventh embodiment of the invention. In this embodiment, thecyclonic separating apparatus450 includes alip452 and first andsecond portions454,456 of a wall. This embodiment is the same as the sixth embodiment except that the annular part extends outwardly.
• FIG. 10 shows an eighth embodiment of the invention. In this embodiment, thecyclonic separating apparatus500 includes alip502 extending from a cylindrically-shapedfirst portion504 of a wall into a region surrounded by asecond portion506 of the wall. Thelip502 comprises two parts—a first part which extends inwardly and a second part which extends parallel to thefirst portion504 of the wall.
• FIG. 11 shows a ninth embodiment of the invention. In this embodiment, thecyclonic separating apparatus550 includes afirst portion552 of a wall which has a cylindrical part and an annular part. Alip554 extends from the annular part of thefirst portion552 into a region surrounded by asecond portion556 of the wall.
• The arrangements illustrated inFIGS. 4 to 11 are intended to show that the number, shape and configuration of the lip or lips can be varied. It will be understood that other arrangements are also possible. For example, the further cyclone assembly may comprise any number of cyclones. Alternatively, the further cyclone assembly need not be present and a filter or other separating media may take its place.
• There need not be a collector or a lip on the collector. What is important is that there is one cyclone which has a wall with two portions of different sizes, and a lip extends from the smaller portion into the larger portion.
• The lips in the above-described embodiments all extend around the whole of the circumference of the wall of the cyclone. However, this need not be so. The lip may extend around only part of the circumference of the wall of the cyclone. Alternatively, a plurality of lips may be provided, each of which extends partly around the circumference of the wall of the cyclone.
• The lip may extend into a small part of the region surrounded by second portion of the wall of the cyclone or, alternatively, the lip may extend further into the cyclone. Any number of lips may be provided; for example, several concentric lips may be provided.

Claims (17)

1. A cyclonic separating apparatus for separating particles from a dirt- and dust-laden airflow comprising a cyclone for separating and collecting dirt and dust from the dirt- and dust-laden airflow, the cyclone having an air inlet, an air outlet, a longitudinal axis and a wall upon which cyclonic separation takes place, the wall comprising a first portion and a second portion spaced further from the longitudinal axis than the first portion, the first and second portions being axially spaced along the longitudinal axis,

wherein the cyclone further comprises at least one lip extending from the first portion of the wall into a portion of the cyclone surrounded by the second portion of the wall.

2. The cyclonic separating apparatus ofclaim 1, wherein the first portion of the wall is cylindrical and has a first radius.

3. The cyclonic separating apparatus ofclaim 2, wherein at least a part of the second portion of the wall is cylindrical and has a second radius.

4. The cyclonic separating apparatus ofclaim 1,2 or3, wherein the first portion of the wall is located between the air inlet and the second portion of the wall.

5. The cyclonic separating apparatus ofclaim 1,2 or3, wherein the at least one lip has a plurality of holes therethrough.

6. The cyclonic separating apparatus ofclaim 1,2 or3, wherein the at least one lip forms a substantially straight extension of the first portion of the wall.

7. The cyclonic separating apparatus ofclaim 1,2 or3, wherein a distal end of the at least one lip is spaced at a distance from the longitudinal axis greater than that of the first portion.

8. The cyclonic separating apparatus ofclaim 1,2 or3, wherein a distal end of the at least one lip is spaced at a distance from the longitudinal axis less than that of the first portion.

9. The cyclonic separating apparatus ofclaim 7, wherein the at least one lip extends from the first portion of the wall at an angle to the longitudinal axis.

10. The cyclonic separating apparatus ofclaim 1,2 or3, wherein a single lip is provided, the lip extending around the circumference of the wall.

11. The cyclonic separating apparatus ofclaim 1,2 or3, further comprising at least one further cyclone and a collector which are located downstream of the air outlet, the at least one further cyclone being arranged to deposit separated dirt and dust into the collector.

12. The cyclonic separating apparatus ofclaim 11, wherein the collector has a longitudinal axis, a wall and at least one further lip extending from the said wall into the collector.

13. The cyclonic separating apparatus ofclaim 12, wherein the further cyclone has an inlet and a cone opening and the at least one further lip extends away from the cone opening of the at least one further cyclone.

14. The cyclonic separating apparatus ofclaim 12, wherein at least a part of the at least one further lip is parallel to a part of the wall of the collector.

15. (canceled)

16. A vacuum cleaner comprising the cyclonic separating apparatus ofclaim 1,2 or3.

17. The vacuum cleaner ofclaim 16, wherein the vacuum cleaner is a hand-held vacuum cleaner.

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