Cyclonic separating unit

Abstract

A cyclonic separating unit for a vacuum cleaning comprises an air inlet 40, an air outlet 60, and a primary airflow path 30 extending therebetween. The cyclonic separating unit further comprises a plu

Description

BACKGROUND Vacuum cleaning appliances typically have a separator for separating dust from an incoming airflow. The separator typically comprises a primary separating unit and a secondary separating unit through which the incoming airflow passes sequentially. This allows larger dirt and debris to be extracted from the airflow' in the primary separating unit, enabling the secondary separating unit to subsequently remove finer dust particles in an efficient manner. In some cases, the secondary separating unit is a cyclonic separating unit including a plurality of cyclones, e.g. arranged fluidically in parallel. SUMMARY In a first aspect, there is provided a cyclonic separating unit for a vacuum cleaning appliance, the cyclonic separating unit comprising: an air inlet, an air outlet, and a primary airflow path extending therebetween; a plurality of cyclones each comprising a respective dust opening, the plurality of cyclones being divided into a first set of cyclones and a second set of cyclones; a first dust collector arranged to receive dust from the first set of cyclones via each respective dust opening; and a second dust collector arranged to receive dust from the second set of cyclones via each respective dust opening; the cyclonic separating unit having a high-power configuration in which the primary airflow' path extends through both the first and the second set of cyclones, and a low-power configuration in which the primary airflow path extends through only the first set of cyclones, wherein the cyclonic separating unit further comprises a secondary' airflow' path fluidly connecting the first dust collector and the second dust collector, such that in use, in the low-power configuration, a pressure differential between the first dust collector and the second dust collector draws air from the first dust, collector into the second dust collector via the secondary airflow path. When the cyclonic separating unit is in the low-power configuration, the first dust collector is at a higher pressure than the second dust collector, thereby developing a pressure differential between the first and second dust collectors. The fluidic connection between the first and second dust collectors allows a proportion of the air supplied to the first set of cyclones via the primary airflow path to be drawn along the secondary airflow path. That is, under the influence of the pressure differential, air is drawn through each dust opening of the first set of cyclones and into the second dust collector via the first dust collector. The passage of air through the dust openings of the first set of cyclones helps dislodge any dust blinding the dust openings by drawing it into the first dust collector. Optional features are discussed below. The invention includes the combination of the aspects and optional features described except where such a combination is clearly impermissible or expressly avoided. For the avoidance of doubt, the secondary air flow path extends from the first dust collector to the second dust collector. There will be a further air flow feeding the secondary air flow path i.e. extending from the primary air flow path through the dust openings of the first set of cyclones and to the secondary air flow path via the first dust collector. The secondary airflow path (extending from the first, to the second dust, collector) may be substantially perpendicular to a central axis of each of the plurality of cyclones. The secondary airflow7 path (extending between the first and second dust collectors) may be located downstream of the dust openings of the first set of cyclones. Thus, when the cyclonic separating unit is in the low-power configuration, the pressure differential which develops between the first dust collector (high pressure) and the second dust collector (low-pressure) draws air from the dust, openings of the first set of cyclones towards the secondary airflow7 path. This helps dislodge any dust stuck in the dust openings of the first set. of cyclones and pull it. down into the first dust collector, towards the secondary airflow path, thereby clearing the dust openings. The first dust collector may extend axially between an upper end in fluid communication with the dust openings of the first set of cyclones, and a base opposite the upper end. The secondary airflow path may be located proximal the base (i.e. closer to the base than to the dust openings). It may be located adjacent the base of the first dust collector. Thus, it can be ensured that any dislodged dust from the dust openings of the first set of cyclones is pulled away from the dust openings as far down into the first dust collector as possible. This helps reduce a risk of dust building up inside the first dust collector in the vicinity of the dust openings of the first set of cyclones which can obstruct the dust openings. The secondary flow path may extend substantially parallel to the base of the first dust collector. The second dust collector may extend axially between an upper end in fluid communication with the dust, openings of the second set of cyclones, and abase opposite the upper end. The secondary airflow path may be located proximal the base (i.e. closer to the base than to the dust openings). It may be located adjacent the base of the second dust collector. The secondary flow path may extend substantially parallel to the base of the second dust collector. The first dust collector may comprise at least one upstream opening through which the secondary flow path extends. The upstream opening(s) may be located downstream of the dust openings of the first set of cyclones. For example, the upstream opening(s) may be located proximal the base of the first dust collector. The second dust collector may comprise at least one downstream opening through which the secondary flow7 path enters the second dust collector (from a respective upstream opening). The downstream opening(s) may be located downstream of the dust openings of the second set of cyclones. For example, the downstream opening(s) may be located proximal the base of the second dust collector. The secondary flow path extends from the upstream openmg(s) in the first dust collector to the downstream opening(s) in the second dust collector. In some embodiments, the first dust collector may be adjoined to the second dust collector via an adjoining wall (e.g. an axially-extending adjoining wall extending from the upper end of the first dust collector to the base of the first dust collector), and the secondary airflow path may be formed through the adjoining wall (e.g. proximal the base of the first dust collector). For example, the adjoining wall may comprise at least one through hole through which the secondary airflow path passes. The upstream opening(s) (in the first dust collector) and the downstream opening(s) (in the second dust collector) may be formed on opposing sides of the adjoining wall and will be in fluid communication with the respective through hole in the adjoining wall. For example, the opening(s) may be coincident with the through hole(s) (i.e. the axes of the respective openings and through hole may be aligned). In some embodiments, the dust collectors may be arranged so as to be concentric e.g. with the first dust collector located radially inwards of the second dust collector. That is, the first dust collector and the second dust collector may be arranged in a nested manner relative to one another. For example, at least the outer dust collector (which may be the second dust collector) may be an annulus. In these embodiments, the first and second dust collectors each extend circumferentially (as well as axially). There may be a circumferentially-extending (and axially-extending) adjoining wall which may define the radially-outer wall of the inner (e.g. first) dust collector and the radially-inner wall of the outer (e.g. second) dust collector. The upstream and downstream opening(s) may be formed on opposing sides of the circuniferentially- / axially-extending adjoining wall. In some embodiments, instead of the dust collectors being arranged concentrically, the first dust collector and the second dust collector may be arranged such that together they at least partially form an annulus. That is, the first and the second dust collectors may be arranged circumferentially in series such that the first dust collector forms a first part of an annulus and the second dust collector forms a second part of the same annulus. In these embodiments, the first and second dust collectors each extend circumferentially (as well as axially). In some examples, the annulus may be completely formed by the first dust-collector and the second dust collector. In other examples, the annulus may be only partially formed by the first dust collector and the second dust collector. There may be a radially-extending (and axially-extending) adjoining wall interposed between the first dust collector and the second dust collector. The upstream and downstream opening(s) may be formed on opposing sides of the radially- / axially-extending adjoining wall. In some embodiments, there may be a channel extending between the first and second dust collectors and the secondary air flow path may extend through the channel. The upstream and downstream openings of the first and second dust collectors wall be in fluid communication with the channel. Thus the first dust collector may comprise a first wall in which the upstream opening(s) is / are formed and the second dust collector may comprise a second wall in which the downstream opening(s) are formed. The first and second walls wall be spaced by the channel. The first and second walls will be axially-extending between the upper ends and bases of the first and second dust collectors respectively. Where the dust collectors are concentrically arranged as described above, the first and second wads may also be circumferentially-extending (and axially extending). When the first dust collector and the second dust collector are annularly arranged as discussed above, the first and second walls may be axially- and radially-extending. The or each upstream opening may be axially-extending along the first side of the adjoining wall or along the first wall. The or each downstream opening may be axially-extending along the second side of the adjoining wall or along the second wall. The cyclonic separating unit may be configured such that the axial extension of the or each upstream opening is at least 5%, such as at least 10% or 20%, for example at least 30% or 40%, such as at least 50% or 60%, e.g. at least 70 or 80% of the axial extension of the first side of the adjoining wall / first wall. Indeed, the axial extension of the or each upstream opening may be at least 90% and even up to 100% of the axial extension of the first side of the adjoining ’wall / first wall. The or each upstream opening may be circumferentially-extending along the first side of the adjoining wall or along the first wall. The or each downstream opening may be circumferentially-extending along the second side of the adjoining wall or along the second wall. The cyclonic separating unit may be configured such that a transverse cross section of the secondary airflow path at the upstream opening(s) (i.e, a cross-section perpendicular to the secondary airflow path e.g. in a plane defined by the axial and circumferential extension of the upstream opening(s)) is at least 5%, such as at least 10% or 20%, for example at least 30% or 40%, such as at least 50% or 60%, e.g. at least 70 or 80% of the surface area of the first side of the adjoining wall or the first wall. Indeed, the transverse cross section of the secondary flow path may be at least 90% and even up to 100% of the surface area of the first, side of the adjoining wall or the first, wall. Generally, the larger the surface area of the transverse cross section of the secondary airflow path, the lesser the risk of accumulated dust obstructing the secondary airflow path, e.g. at the through hole. The secondary' airflow path may comprise at least one dust filter configured to prevent dust migration between the first, dust collector and the second dust collector. The dust filter(s) may have a meshed and / or porous structure. The dust filter(s) may be dimensioned to extend transversely across the entirety of the secondary airflow path. The dust filter(s) may be located across the upstream opening(s) to the secondary airflow-path in the first dust collector. The dust filter(s) may be located on the first side of the adjoining wall. The dust filter / s) may be located on the first wall. The dust filter(s) may be located within the through hole(s) through the adjoining wall. The dust filter(s) may be located within the channel. The plurality of cyclones may be arranged fluidic-ally in parallel. Each of the plurality of cyclones may be hollow' and generally conical in shape. For example, each of the plurality of cyclones may be frustoconical. Each dust opening may be located at. the frustum of its respective cyclone. The plurality of cyclones may define a central channel, with the cyclones arranged about the central channel. The air inlet of the cyclonic separating unit-may be located in or at the central channel. The plurality of cyclones may be provided as a single moulded arrangement. The first set of cyclones and the second set of cyclones may be arranged such that together they at least partially form an annulus. That is, the first and the second sets of cyclones may be arranged circumferentially in series such that the first set of cyclones forms a first part of an annulus and the second set of cyclones forms a second part of the same annulus. For example, the plurality of cyclones may be arranged in a substantially frustoconical manner along the central channel. Alternatively, the first set of cyclones and the second set of cyclones may be arranged in a nested configuration, i.e. such that, the first set of cyclones and the second set of cyclones are concentric with respect to the central channel. For example, at least the outer set of cyclones (which may be the second set of cyclones) may be annularly shaped. The cyclonic separating unit may further comprise a valve movable between a first position in which the valve allows the primary airflow path to extend through both the first and second set of cyclones, and a second position in which the valve prevents the primary airflow path from extending through the second set of cyclones. The valve may be mounted inside the air inlet of the cyclonic separating unit. The valve may be located at or inside the central channel defined by the plurality of cyclones. The valve may be movable axially along the central channel to transition between the first position and the second position. In a second aspect, there is provided a separator for a vacuum cleaning appliance, the separator comprising: a primary separating unit comprising a primary air inlet and a primary air outlet; and the cyclonic separating unit of the first aspect; wherein the primary air outlet is fluidly connected to the air inlet of the cyclonic separating unit. That is, the primary separating unit and the cyclonic separating unit are arranged fluidically in series and the cyclonic separating unit is downstream of primary separating unit, along the primary? airflow path. In a third aspect, there is provided a vacuum cleaning appliance comprising the cyclonic separating unit of the first aspect or the separator of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically shows a perspective view of a part of a cyclonic separating unit according to an embodiment of the present invention; Fig. 2A schematically shows a partial cross-sectional view of a cyclonic separating unit according to an embodiment of the present invention which is in a high-power configuration; Fig. 2B schematically shows a partial cross-sectional view of the cyclonic separating unit of Fig. 2A in a low-power configuration; Fig. 3 schematically shows a perspective view7 of a cyclonic separating unit according to an embodiment of the present invention; Fig. 4A schematically show's a cross-sectional view of a part of a cyclonic separating unit according to an embodiment of the present invention with a valve in a first position, Fig. 4B schematically shows a cross-sectional view of a part of the cyclonic separating unit of Fig. 4 A with the valve in a second position; Fig. 5 schematically shows a perspective view of a separator for a vacuum cleaning appliance according to an embodiment of the present invention; and Fig. 6 schematically shows a perspective view of a vacuum cleaning appliance according to an embodiment of the present invention. DETAILED DESCRIPTION A cyclonic separating unit according to embodiments of the present invention is discussed below' with reference to Figs 1-4B. With reference to Fig. 1, the cyclonic separating unit 1 comprises a plurality of cyclones 2. The plurality of cyclones 2 is arranged fluidically in parallel. Each cyclone is hollow and generally conical, specifically frustoconical, in shape. Each cyclone of the plurality of cyclones 2 comprises a respective dust opening 13, 14. Each dust opening is located at the frustum of its respective cyclone (see Fig. 2). The plurality of cyclones 2 is divided into a first set of cyclones 11 and a second set of cyclones 12. In the example of Fig. 1, the first set of cyclones includes six cyclones, and the second set of cyclones includes five cyclones. In the example of Fig. 3, the first set of cyclones 11 instead comprises five cyclones and the second set of cyclones 12 comprises four cyclones. However, the total number of cyclones, as well as their relative distribution between the first set and the second set, can vary depending on the requirements of the vacuum cleaning appliance. In all the examples shown the plurality of cyclones 2 is provided as a single moulded arrangement defining a central channel 17, with the cyclones 2 arranged about the central channel. In the examples of Figs I, 3 4A and 4B the plurality of cyclones 2 is arranged such that together they at least partially form an annulus. That is, the first 11 and the second 12 sets of cyclones are arranged such that the first set of cyclones 11 forms a first part of an annulus and the second set of cyclones 12 forms a second part of the same annulus. More specifically, the plurality of cyclones 2 is arranged in a substantially frustoconical manner along the central channel 17. Alternatively, the plurality of cyclones 2 may be arranged in a nested manner, i.e. such that the first set of cyclones 11 and the second set of cyclones 12 are concentric with respect to the central channel 17. This is shown in Figs 2A and 2B where the second set of cyclones 12 is substantially annularly (e.g. frustoconically) shaped, the first set of cyclones 11 is also substantially annularly shaped (e.g. frustoconically), and the first set of cyclones is nested within the inner space defined by the second set of cyclones. With reference to Figs 2A and 2B, the cyclonic separating unit I further comprises an air inlet 40, an air outlet 60, and a primary airflow path 30 extending therebetween. In use, suctioned dust-carrying airflow' flows along the primary airflow path 30 through the cyclonic separating unit 1 such that dust is cyclonically separated from the dust-carrying airflow via the plurality of cyclones 2. The cyclonic separating unit 1 further comprises a first dust collector 21 arranged to receive dust from the first set of cyclones 11 via each respective dust opening 13. The cyclonic separating unit 1 also comprises a second dust collector 22 arranged to receive dust from the second set of cyclones 12 via each respective dust opening 14. Thus, the separated dust falls down the cyclones 2 and into the respective dust collector 21, 22. As shown in Fig. 2B, the cyclonic separating unit 1 also comprises a secondary airflow path 15 fluidly connecting the first dust collector 21 and the second dust collector 22. The secondary airflow path 15 is substantially perpendicular to a central axis of each of the plurality of cyclones. In the example of Figs 2A and 2B, the first 21 and second 22 dust collectors are arranged so as to be concentric, with the first dust collector located radially inwards of the second dust collector. Each of the first 21 and second 22 dust collector is an annulus. The first 21 and second 22 dust collectors each extend circumferentially (as well as axially). Alternatively, the dust collectors 21, 22 can be arranged such that together they at least partially form an annulus. That is schematically shown in Fig. 3 where the first 21 and the second 22 dust collectors are arranged circumferentially in series such that the first dust collector forms a first part of an annulus and the second dust collector forms a second part of the same annulus. In the example of Fig. 3, the annulus is only partially formed by the first dust collector 21 and the second dust collector 22. With reference to any one of Figs 2A, 2B or 3, the first dust collector 21 comprises a base 7 and an upper end 8 opposite the base and in fluid communication with the dust openings 13 of the first set of cyclones 11. The first dust collector 21 is adjoined to the second dust collector 22 via an adjoining w'all 6, and the secondary airflow path 15 is formed through the adjoining wall. When the first 21 and second 22 dust collectors are concentric, as shown in Figs 2A and 2B, the adjoining wall 6 is circumferentially-extending and forms the radially inner wall of the annular second dust collector 22 and the radially outer wall of the annular first dust collector 21. When the first 21 and the second 22 dust collectors are arranged annularly as shown in Fig. 3, the adjoining wall 6 extends radially and axially therebetween. The secondary airflow path 15 comprises a dust filter 5 configured to prevent dust migration between the first dust collector 21 and the second dust collector 22. The dust filter 5 has a meshed and / or porous structure. In this example, the dust filter 5 is located across an upstream opening to the secondary airflow path 15 in the first dust collector 21, on a first side of the adjoining wall 6. The upstream opening, and thus the secondary airflow path 15, is located downstream of the dust openings 13 of the first set of cyclones 11. Specifically, the upstream opening and the secondary' airflow path 15 are located proximal the base 7 of the first dust collector 21. The axial extent of the secondary airflow path 15 at the first side of the adjoining wall 6 is around 50% of the axial extent of the adjoining wall 6. The dust filter 5 may occupy at least 50% of the surface area of the adjoining wall 6. Next, the cyclonic separating unit I also comprises a valve 20 movable between a first position in which the valve allows the primary airflow path 30 to extend through both the first 11 and the second 12 set of cyclones 2 (see Figs 2A and 4A), and a second position in which the valve 20 prevents the primary airflow path 30 from extending through the second set of cyclones 12 (see Fig 2B and 4B). The valve 20 is mounted inside the air inlet 40 of the cyclonic separating unit 1. With reference to Figs 4A and 4B, the valve 20 is located inside the central channel 17 defined by the plurality of cyclones 2. To transition between the first position and the second position, the valve 20 is movable axially along the central channel 17. Thus, in the first position (as shown in Fig. 4A) the valve allows air to flow into the air inlets 3, 3’ of both the first 11 and the second 12 set of cyclones. In the second position (as shown in Fig. 4B), the valve 20 obstructs the inlets 3’ of the second set of cyclones 12 thereby preventing the primary7 airflow path 30 from extending through the second set of cyclones. The first position of the valve 20 corresponds to a high-power configuration of the cyclonic separating unit 1 (shown in Fig. 2A). The second position of the valve 20 corresponds to a low-power configuration of the cy clonic separating unit 1 (shown in Fig. 2B). With reference to Fig. 213, in the low-power configuration, a pressure differential develops in use between the first dust collector 21 and the second dust collector 22. That is, the first dust collector 21 is at a higher pressure than the second dust collector 22 due to the primary airflow path 30 passing through the first set of cyclones 11 but not through the second set of cyclones 12. The pressure differential draws air from the first dust collector 21 into the second dust collector 22 via the secondary' airflow path 15. The cyclonic separating unit 1 can be provided as part, of a separator 10 for a vacuum cleaning appliance. This is discussed with reference to Fig. 5. The separator 10 comprises a primary separating unit 50 comprising a primary' air inlet 51 and a primary air outlet (not visible). The separator 1 also comprises the cyclonic separating unit 1 described with reference to Figs 1-4B above. The primary air outlet of the primary separating unit is fluidly connected to the air inlet 40 of the cyclonic separating unit 1. That is, the primary' separating unit 50 and the cyclonic separating unit 1 are arranged fluidically in series and the cyclonic separating unit is downstream of primary' separating unit, along the primary airflow path 30. The primary separating unit 50 may be cyclonic, or non-cyclonic. Finally, cyclonic separating unit 1 can be provided as part of a vacuum cleaning appliance 100. One example of this is shown in Fig. 6 in which the vacuum cleaning appliance 100 comprises the separator 10 discussed with reference to Fig. 5.

Claims

1. A cyclonic separating unit for a vacuum cleaning appliance, the cyclonic separating unit comprising:an air inlet, an air outlet, and a primary' airflow path extending therebetween;a plurality of cyclones each comprising a respective dust opening, the plurality of cyclones being divided into a first set of cyclones and a second set of cyclones;a first dust collector arranged to receive dust from the first set of cyclones via each respective dust opening, anda second dust collector arranged to receive dust from the second set of cyclones via each respective dust opening;the cyclonic separating unit having a high-power configuration in which the primary airflow path extends through both the first and the second set of cyclones, and a low'-power configuration in which the primary airflow path extends through only the first set of cyclones,wherein the cyclonic separating unit further comprises a secondary airflow path fluidly connecting the first dust collector and the second dust collector, such that in use, in the low-power configuration, a pressure differential between the first dust collector and the second dust collector draws air from the first dust collector into the second dust collector via the secondary airflow path.

2. The cyclonic separating unit of claim 1 wherein the secondary airflow path is located downstream of the dust openings of the first set of cyclones.

3. The cyclonic separating unit of claim 2 wherein the first dust collector extends axially between an upper end in fluid communication with the dust openings of the first set of cyclones, and a base opposite the upper end, the secondary airflow path being located proximal the base.

4. The cyclonic separating unit of any preceding claim wherein the first dust collector is adjoined to the second dust collector via an adjoining wall, and the secondary airflow' path is formed through the adjoining wall.

5. The cyclonic separating unit of claim 4 wherein a transverse cross section of the secondary airflow path at the adjoining wall occupies at least 5% of the surface area of the adjoining wall.

6. The cyclonic separating unit of any preceding claim wherein the secondary’ airflow path comprises a dust filter configured to prevent dust migration between the first dust collector and the second dust collector.

7. The cyclonic separating unit of claim 6 wherein the dust filter is located across an upstream opening to the secondary? airflow path in the first dust collector.

8. The cyclonic separating unit of any preceding claim wherein the cyclonic separating unit further comprises a valve movable between a first position in which the valve allows the primary airflow? path to extend through both the first, and second set of cyclones, and a second position in which the valve prevents the primary airflow path from extending through the second set of cyclones.

9. A separator for a vacuum cleaning appliance, the separator comprising:a primary separating unit comprising a primary air inlet and a primary air outlet; andthe cyclonic separating unit of any preceding claim;wherein the primary’ air outlet is fluidly connected to the air inlet of the cyclonic separating unit.

10. A vacuum cleaning appliance comprising the separator of claim 9.

11. A vacuum cl eaning appliance comprising the cyclonic separating unit of any one ofclaims 1-8.

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