Patent Application
20090313958
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.
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.
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.
Embodiments of the invention will now be described with reference to the accompanying drawings, in which:
The cyclonic separating apparatus 100 forming part of the hand-held vacuum cleaner 10 is shown in more detail in
The first portion 106 of the wall 104 is substantially cylindrical and is in two parts. This is so that the parts can be separated to allow cleaning of the interior of the cyclone 102. However, this is not material to the invention. The second portion 108 of the wall 104 is spaced further from the longitudinal axis X-X than the first portion 106 of the wall 104. The second portion 108 of the wall 104 includes a shoulder 112 and a cylindrical part 113. A lip 114 extends from the first portion 106 of the wall 104 into the space surrounded by the second portion 108 of the wall 104 of the cyclone 102. The lip 114 forms a substantially straight extension of the first portion 106 of the wall 104. The function of the lip 114 will be described later.
A base 116 closes one end of the cyclone 102. The base 116 is pivotably mounted on the lower end of the second portion 108 of the wall 104 by means of a hinge 118. The base 116 is retained in a closed position (as shown in
A shroud 121 is located inwardly of the wall 104 of the cyclone 102. The shroud 121 comprises a cylindrical wall 122 having a plurality of through-holes 123. The shroud 121 surrounds an outlet 124 from the cyclone 102. The outlet 124 provides a communication path between the cyclone 102 and a further cyclone assembly 126. A lip 128 is provided at the base of the shroud 121. The lip 128 has a plurality of through-holes which are designed to allow air to pass through but to capture dirt and dust.
The further cyclone assembly 126 comprises a plurality of further cyclones 130 arranged in parallel. In this embodiment, six further cyclones 130 are provided. Each further cyclone 130 has a tangentially-arranged air inlet 132 and an air outlet 134. Each air inlet 132 and air outlet 134 is located at a first end of the respective further cyclone 130. A cone opening 136 is located at a second end of each further cyclone 130. The cone opening 136 of each further cyclone 130 is inclined with respect to a longitudinal axis (not shown) of the respective further cyclone 130 as can be best seen in
A collector 142 is located at the lower end of the passageway 138. The collector 142 comprises a frustoconical first portion 144 and a cylindrical second portion 146. The interior of the collector 142 is surrounded by the base 116 and the sides of the first and second portions 144, 146 of the collector 142.
A further lip 148 extends into the portion of the collector 142 surrounded by the cylindrical second portion 146. The further lip 148 comprises a frustoconical portion 148a and a cylindrical portion 148b which extends substantially parallel to the sides of the second portion 146 of the collector 142. The function of the further lip 148 will be described later.
Each of the air outlets 134 of the further cyclones 130 is in communication with a duct 150. The duct 150 provides an airflow path from the cyclonic separating apparatus 100 into other parts of the hand-held vacuum cleaner 10. Located at the downstream end of the duct 150 is a pre-motor filter 152. The pre-motor filter 152 comprises a porous material such as foam.
In use, the motor and fan unit draws a flow of dirt-laden air into the dirty air inlet 20, through the inlet pipe 18 and into the cyclonic separating apparatus 100. Dirt-laden air enters the cyclonic separating apparatus 100 through the inlet 110. Due to the tangential arrangement of the inlet 110, the airflow is forced to follow a helical path around the interior of the wall 104. Larger dirt and dust particles are separated by cyclonic motion around the wall 104. These particles are then collected at the base 116 of the cyclone 102. Separation of larger particles will occur in the region of the cyclone 102 surrounded by the first portion 106 of the wall 104 and also the portion of the cyclone 102 surrounded by the lip 114. Separated particles gather in the portion of the cyclone 102 surrounded by the second portion 108 of the wall 104.
The partially-cleaned airflow then flows back up the interior of the cyclone 102 and exits the cyclone 102 via the through-holes in the shroud 121. Once the airflow has passed through the shroud 121, it enters the outlet 124 and from there is divided between the tangential inlets 132 of each of the further cyclones 130. Each of the further cyclones 130 has a diameter smaller than that of the cyclone 102. Therefore, the further cyclones 130 are able to separate smaller particles of dirt and dust from the partially-cleaned airflow than the cyclone 102. Separated dirt and dust exits the further cyclones 130 via the cone openings 136. Thereafter, the separated dirt and dust passes down the passageway 138 and into the collector 142. The separated dirt and dust eventually settles at the base of the collector 142.
Cleaned air then flows back up the further cyclones 130, exits the further cyclones 130 through the air outlets 134 and enters the duct 150. The cleaned air then passes from the duct 150 sequentially through the pre-motor filter 152, the motor and fan unit, and a post-motor filter before being exhausted from the vacuum cleaner 10 through the air vents 24.
It is likely that, in use, the hand-held vacuum cleaner 10 will be held in a variety of orientations. It may even be held upside down in use. When the cyclonic separating apparatus 100 is tilted away from the vertical, a large proportion of the separated dirt and dust that may otherwise move towards the inlet 110 and the shroud 121 is caught in an annular pocket created between the lip 114 and the second portion 108 of the wall 104. Further, the presence of the above-described pocket may assist in the creation of stagnation points and eddy-currents within the lower portion of the cyclone 102. This may further prevent re-entrainment of separated dirt and dust into the return airflow.
Regarding the collector 142, a pocket is created between the second portion 146 of the collector 142 and the further lip 148. The pocket will prevent a proportion of the separated dirt and dust which may potentially block the cone openings 136 or other parts of the further cyclones 130 from re-entering the passageway 138 when the hand-held vacuum cleaner 10 is tilted away from the vertical.
The cyclone 102 and collector 142 can be emptied simultaneously by releasing the catch 120 to allow the base 116 to pivot about the hinge 118 so that the separated dirt and dust can fall away from the cyclonic separating apparatus 100.
Both the lip 114 and the further lip 148 may take different configurations or shapes from those shown in the first embodiment.
The arrangements illustrated in
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0614237.6 | Jul 2006 | GB | national |
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.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB07/02525 | 7/6/2007 | WO | 00 | 7/31/2009 |
