GB2612981A

GB2612981A - Dirt separator

Info

Publication number: GB2612981A
Application number: GB2116584.0A
Authority: GB
Inventors: Been Lee Kent; Mohd Rozaimi Che Mohd Nor Che; Kiong Pang Kian
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2021-11-17
Filing date: 2021-11-17
Publication date: 2023-05-24
Anticipated expiration: 2041-11-17
Also published as: GB202116584D0; GB2612981B; WO2023089297A1

Abstract

A filter (44, fig 2) suitable for use in a dirt separator (18, fig.2), the filter comprising a first face, a second face, and a through-hole 50 extending between the first and second faces. The filter includes a chamfer 64 extending only partially around a periphery of the through-hole on the first face. Also claimed, is a dirt separator suitable for separating dirt from an airflow which includes an air inlet, an air outlet, and the described filter located between the air inlet and outlet. The filter may comprise a further chamfer 66 extending only partially around a further periphery of the through-hole on the second face. The dirt separator may also comprise a cyclonic separator and a wiping mechanism (56, fig. 2) for wiping the first face. The through-hole may be generally circular in cross-section and comprise a diameter in the region of 200 µm to 600 µm. The invention aims to provide easy removal of debris from the filter hole (especially hair) and to reduce airflow eddies whilst providing low failure rate during manufacturing.

Description

DIRT SEPARATOR

Field of the Invention

The present invention relates to a dirt separator, a filter for a dirt separator, and a vacuum cleaner comprising such a dirt separator or filter.

Background of the Invention

Vacuum cleaners typically employ dirt separators for separating dirt from an airflow entrained by the vacuum cleaner in use. Some dirt separators may utilise filters to aid in dirt separation

Summary of the Invention

According to a first aspect of the present invention there is provided a dirt separator for separating dirt from an airflow, the dirt separator comprising an air inlet, an air outlet, and a filter located between the air inlet and the air outlet, the filter comprising a first face, a second face, and a through-hole extending between the first and second faces, wherein the filter comprises a chamfer extending only partially around a periphery of the through-hole on the first face.

Providing a filter comprising a chamfer extending only partially around a periphery of the through-hole on the first face may provide increased ease of removal of elongate debris, for example hair, from the filter, whilst also providing a filter which is manufacturable with a relatively low failure rate.

In particular, it has been found that provision of a filter with a through-hole comprising sharp edges, for example without a chamfer, within a dirt separator of a vacuum cleaner, can lead to clogging of the through-hole by elongate dirt particles or debris such as hair, with such elongate dirt particles of hair proving relatively difficult to remove from the filter. This may particularly be the case when cleaning of the filter by wiping, for example using a blade or other material, in a direction substantially parallel to a periphery of the through-hole occurs. Indeed, it has been found that when performing such wiping, sharp edges of the periphery of the through-hole may shred or cut hair cuticles, leading to hair becoming stuck in the through-hole, and requiring manual removal of the hair by a user. This may be unhygienic, and thus undesirable for a user.

By providing a chamfer around the periphery of the through-hole, it has been found that less shredding of hair by the periphery of the through-hole may occur when cleaning the filter by wiping, for example compared to an arrangement where no chamfer is provided. It has further been found that provision of a chamfer around the periphery of the through-hole may result in a lower force required to remove hair from the through-hole of the filter compared to, for example, an arrangement where no chamfer is provided Provision of a chamfer may further reduce airflow eddies in a region of the periphery of the through-hole, for example compared to an arrangement where no chamfer is provided and sharp edges occur.

However, provision of a chamfer extending fully around a periphery of the through-hole may, in some circumstances, lead to a relatively high failure rate during manufacture. It has been found that provision of a chamfer extending only partially around a periphery of the through-hole on the first face may provide the aforementioned benefits in relation to less shredding of hair, lower hair removal force, and/or reduction in airflow eddies, compared to an arrangement where no chamfer is provided, whilst also enabling manufacturing with a relatively low failure rate compared to an arrangement where a chamfer is provided that extends fully about the periphery of the through-hole on the first face. Provision of chamfer that extends only partially around a periphery of the through-hole may provide an increased strength of filter compared to, for example, an arrangement where a chamfer is provided that extends fully about the periphery of the through-hole on the first face, as less material may be required to be removed from the filter when creating the chamfer.

The chamfer may extend around no more than 75%, no more than 60%, or no more than 50% of the periphery of the through-hole on the first face. It has been found that the extent of the chamfer may be reduced whilst still providing the aforementioned benefits of less shredding of hair, lower hair removal force, reduction in airflow eddies, increased strength and/or lower failure rate during manufacture. The chamfer may extend around 50% of the periphery of the through-hole on the first face. The through-hole may be substantially circular in cross-section, and the chamfer may extend around no more than 180° of the periphery of the through-hole on the first face The filter may comprise a further chamfer extending only partially around a Iiirther periphery of the through-hole on the second face. This may result in less shredding of hair by the further periphery of the through-hole when cleaning the first face filter by wiping, for example compared to an arrangement where no chamfer is provided on the further periphery of the through-hole. It has further been found that provision of a chamfer around the further periphery of the through-hole may result in a lower force required to remove hair from the through-hole of the filter compared to, for example, an arrangement where no chamfer is provided. Provision of a chamfer may further reduce airflow eddies in a region of the further periphery of the through-hole, for example compared to an arrangement where no chamfer is provided and sharp edges occur.

However, provision of a chamfer extending fully around the further periphery of the through-hole may, in some circumstances, lead to a relatively high failure rate during manufacture. It has been found that provision of a chamfer extending only partially around the further periphery of the through-hole on the second face may provide the aforementioned benefits in relation to less shredding of hair, lower hair removal force, and/or reduction in airflow eddies, compared to an arrangement where no chamfer is provided, whilst also enabling manufacturing with a relatively low failure rate compared to an arrangement where a chamfer is provided that extends fully about the further periphery of the through-hole on the second face. Provision of chamfer that extends only partially around the further periphery of the through-hole may provide an increased strength of filter compared to, for example, an arrangement where a chamfer is provided that extends fully about the further periphery of the through-hole on the second face, as less material may be required to be removed from the filter when creating the chamfer. The further chamfer may extend around no more than 75%, no more than 60%, or no more than 50% of the further periphery of the through-hole on the second face. It has been found that the extent of the further chamfer may be reduced whilst still providing the aforementioned benefits of less shredding of hair, lower hair removal force, reduction in airflow eddies, increased strength and/or lower failure rate during manufacture. The further chamfer may extend around 50% of the further periphery of the through-hole on the second face. The through-hole may be substantially circular in cross-section, and the further chamfer may extend around no more than 180° of the further periphery of the through-hole on the second face.

The chamfer and the further chamfer may be located on diametrically opposite sides of the respective periphery and further periphery of the through-hole, for example with the chamfer extending around a first, lower, side of the periphery of the through-hole on the first face, and the further chamfer extending around a second, upper side of the further periphery of the through-hole on the second face. This may define a substantially diagonal path through the through-hole, for example from the first side of the filter to the second side of the filter, which may assist with reducing shredding of hair when wiping the filter, and may assist with reducing the force required to remove hair from the through-hole.

The through-hole may comprise a central axis extending between the first and second faces, the periphery of the through-hole on the first face comprises a first side and a second side relative to an axis orthogonal to the central axis, the further periphery of the through-hole on the second face comprises a third side corresponding to the first side, and a fourth side corresponding to the second side, the chamfer extends around the first side of the periphery of the through-hole on the first face, and the further chamfer extends around the fourth side of the further periphery of the through-hole on the second face. In such a manner the chamfer and the further chamfer may not overlap with one another when viewed in a cross-section taken along the central axis.

The dirt separator may comprise a cyclonic separator, for example a separator configured to separate dirt via cyclonic separation. The dirt separator may comprise a housing in which the air inlet is formed, with the housing configured to generate a helical airflow within the housing in use. The housing may comprise a substantially cylindrical global form. The filter may be positioned within the housing such that a substantially helical airflow is generated between the housing and the filter in use. For example, the filter may define a curved surface within the housing. The first face of the filter may define a curved surface within the housing.

The filter may be substantially cylindrical in form, for example such that the first face comprises an outer face of the filter and the second face comprises an inner face of the filter. In such a manner the through-hole may define an airflow path through the filter in use, with dirt or debris larger than the through-hole unable to pass through the through-hole. The first face may comprise an upstream face of the filter and the second face may comprise a downstream face of the filter.

The dirt separator may comprise a wiping mechanism for wiping the first face. Thus may enable dirt or debris to be removed from the first face of the filter, for example without a user needing to manually remove dirt or debris using their hands or a cloth or the like.

The wiping mechanism may comprise a blade movable relative to the first face from a first position to a second position, for example in a direction parallel to a central axis of the filter, and the chamfer may be located such that the blade passes over a portion of the periphery of the through-hole that does not comprise the chamfer before passing over the chamfer when moving from the first position to the second position. Such a location of the chamfer may enable a reduced force required to remove dirt or debris such as hair from the through-hole, and may aid with removal of hair from the filter by the wiping mechanism.

The dirt separator may comprise a dust outlet movable between a closed position and an open position. Movement of the blade from the first position to the second position may move the dust outlet from the closed position to the open position, and vice versa.

A depth of the chamfer may decrease in a direction from the first position to the second position. This may aid with removal of dirt or debris such as hair from the through-hole. A depth of the further chamfer may increase in a direction from the first position to the second position The through-hole may comprise a first width, for example a diameter, the chamfer may comprise a second width less than the first width, and a ratio of the second width to the first width may be in the region of 0.1 to 0.5. Such a ratio may aid with removal of dirt or debris such as hair from the through-hole, for example by reducing a force required to remove dirt or debris such as hair from the through-hole, and may aid with removal of hair from the filter by the wiping mechanism. The ratio of the second width to the first width may in the region of 0.3, for example in the region of one third.

The through-hole may be generally circular in cross-section, and may comprise a diameter in the region of 200pm to 600m, for example around 300p.m. Such a through-hole size may prohibit relatively large dirt or debris from passing through the through-hole, and may, for example, provide a filter that finds particular utility in a vacuum cleaner. The second with may be in the region of 80pm to 150pm, for example around 100pm.

The through-hole may comprise a first maximal depth between the first and second faces, the chamfer may comprise a second maximal depth less than the first maximal depth, and a ratio of the second maximal depth to the first maximal depth may be in the region of 0.4 to 0.6, for example around 0.5. This may provide a comprise between aiding removal of dirt or debris such as hair from the through-hole whilst providing a filter of sufficient structural integrity. The further chamfer may comprise a third maximal depth less than the first maximal depth, and a ratio of the third maximal depth to the first maximal depth may be in the region of 0.4 to 0.6, for example around 0.5. The second maximal depth and the third maximal depth may be substantially the same.

The chamfer may be formed on the filter by chemical etching. The further chamfer may be formed on the filter by chemical etching.

The filter may comprise a plurality of through-holes, and a plurality of chamfers each extending only partially about a corresponding periphery of a through-hole on the first face. The filter may comprise a plurality of further chamfers extending only partially about a corresponding periphery of a through-hole on the second face.

According to a second aspect of the present invention there is provided a filter for a dirt separator, the filter comprising a first face, a second face, and a through-hole extending between the first and second faces, wherein the filter comprises a chamfer extending only partially around a periphery of the through-hole on the first face.

According to a third aspect of the present invention there is provided a vacuum cleaner comprising a dirt separator according to the first aspect of the present invention, and/or a filter according to the second aspect of the present invention.

The vacuum cleaner may comprise a handheld unit comprising the dirt separator and a suction motor for generating an airflow from the air inlet of the dirt separator to the air outlet of the dirt separator. The vacuum cleaner may comprise a cleaner head releasably attachable to the handheld unit, for example directly attachable or attachable via one or more intermediate tubes

Brief Description of the Drawings

Figure I is a perspective view of a vacuum cleaner; Figure 2 is a side view of a handheld unit of the vacuum cleaner of Figure 1 in a first configuration, Figure 3 is a side view of the handheld unit of Figure 2 in a second configuration; Figure 4 is a schematic view of a first face of a filter of the handheld unit of Figure 2, Figure 5 is an enlarged cross-sectional view through the filter of Figure 4, Figure 6 is a schematic view of a second face of the filter of Figure 4, Figure 7 is a second schematic view of the first face of the filter; Figure 8 is a cross-section taken along the line C-C of Figure 7; Figure 9 is a cross-section taken along the line D-D of Figure 7; Figure 10 is a cross-section taken along the line E-E of Figure 7; and Figure 11 is a plot of through-hole size vs force for illustrative filters.

Detailed Description of the Invention

A vacuum cleaner 10 is illustrated in Figure 1, and comprises a handheld unit 12, a cleaner head 14, and an elongate tube 16. The handheld unit 12 is releasably attached to the cleaner head 14 by the elongate tube 16, and in an alternative configuration the handheld unit 12 can be directly attached to the cleaner head N. The handheld unit 12 comprises a dirt separator 18, and a main body 20. The main body 30 20 is shaped to define a handle 22, and houses a battery pack 24 and a suction motor 26.

The dirt separator 18 comprises a primary cyclonic stage 28 and a secondary cyclonic stage 30. The primary cyclonic stage 28 comprises a separation chamber 32 defined by a lower wall 34, an upper wall 36 and a curved wall 38 between the lower 34 and upper 36 walls, such that the separation chamber 32 is generally cylindrical in form. An opening in the lower wall 34 defines an air inlet 40 of the dirt separator 18. The lower wall 34 is pivotally connected to the curved wall 38 such that the lower wall 34 can move relative to the curved wall 38, thereby defining a dirt outlet that enables dirt and debris to be removed from the separation chamber 32 of the dirt separator 18.

The separation chamber 32 houses a filter 44 in the form of a shroud. The filter 44 is arranged in a generally cylindrical manner within the separation chamber 32, and comprises a plurality of through-holes 50 as will be described in more detail hereafter.

The secondary cyclonic stage 30 comprises a plurality of relatively small cyclone bodies 52 and a fine dust collection chamber 46 that extends through the separation chamber 32.

The lower wall 34 of the separation chamber 32 also acts as a closure for the fine dust collection chamber 46.

During operation of the vacuum cleaner 10, the battery pack 24 provides electrical power to the suction motor 26 to generate an airflow through the vacuum cleaner 10. A surface to be cleaned is agitated by a brushbar (not shown) within the cleaner head 14, such that dirt is entrained within the airflow flowing through the vacuum cleaner 10. Dirt-laden air enters the dirt separator 18 through the air inlet 40, and flows within the separation chamber 32 in a helical manner.

Larger dirt and debris is removed from the airflow due to centrifugal forces as the airflow flows within the separation chamber 32. After the larger dirt and debris has been separated from the airflow in the separation chamber, the airflow passes through the filter 44 and enters the secondary cyclonic stage 30. The small cyclone bodies 52 are able to separate any finer dust that was able to pass through the filter 44, and the fine dust passes into the fine dust collection chamber 46. Cleaned airflow exits the secondary cyclonic stage 30, and hence the dirt separator 18, through air outlets 54 of the small cyclone bodies 52. Although not illustrated, in some examples the airflow then passes through a motor pre-filter, the suction motor 26 and a motor post-filter 27, before being expelled into the atmosphere.

As airflow moves within the separation chamber 32 and through the through-holes 50 of the filter 44, dirt and debris can become trapped in or on the filter 44. To facilitate cleaning of the filter 44, the dirt separator 18 comprises a wiping mechanism 56. The wiping mechanism comprises a blade 58, a track 60, and an actuator 62. In some examples the blade 58 comprises a silicone rubber wiper.

The blade 58 is fixedly attached to the curved wall 38 of the separation chamber 32, and extends inwardly from the curved wall 38 to contact the filter 44 The curved wall 38 of the separation chamber 32 is movable relative to the small cyclone bodies 52 along the track 60, for example with the curved wall 38 comprising an engagement feature (not shown) for slidably engaging with the track 60 The actuator 62 is fixedly attached to an outer surface of the curved wall 38 of the separation chamber 32 such that application of a force by a user to the actuator 62 moves the curved wall 38 along the track 60.

In particular, when a user applies a force to the actuator 62 in the direction indicated by arrow A in Figure 2, which is in a direction parallel to a central axis of the filter 44 and the separation chamber 32 and away from the handle 22, the curved wall 38 is movable along the track 60 from a first position shown in Figure 2, to a second position shown in Figure 3. As the curved wall 38 moves along the track 60, the blade 58 moves relative to, and contacts, the filter 44, such that the blade 58 wipes the outer face of the filter 44 when moving from the first position of Figure 2 to the second position of Figure 3 In such a manner, dirt and debris stuck to the filter 44 may be removed from the filter 44 by the blade 58 As shown in Figure 3, actuation of the actuator 62 in such a manner also moves the lower wall 34 relative to the curved wall 38, for example to open the separation chamber 32, such that dirt and debris is ejected from the separation chamber 32 and the fine dust collection chamber 46.

Whilst wiping of the filter 44 in such a manner has been found to aid with removal of dirt and debris trapped on the surface of the filter 44, it has also been found that, in some cases, elongate dirt and debris such as hair may remain trapped on the filter 44 in spite of the action of the blade 58. In particular, elongate dirt and debris such as hair can become trapped in the through-holes 50 of the filter 44.

To aid with removal of dirt and debris, the filter 44 comprises a first chamfer 64 and a second chamfer 66 located about the periphery of each respective through-hole 50, with a single through-hole 50 illustrated schematically in each of Figures 4 to 10. The first 64 and second 66 chamfers are formed on the filter by a chemical etching process.

The filter 44 has a first face 68, which is an outer/upstream face, and a second face 70, which is an inner/downstream face, and the through-hole 50 extends between the first 68 and second 70 faces.

As illustrated in Figure 4, the first chamfer 64 extends only partially about a periphery of the through-hole 50 on the first face 68 of the filter 44, with the first chamfer 64 extending about a lower half of the periphery. The through-hole 50 is substantially circular in cross-section, with the first chamfer 64 being generally U-shaped in profile when viewed in Figure 4, and the second chamfer 66 being generally inverted U-shaped in profile when viewed in Figure 6.

The through-hole 50 has a diameter in the region of 200pm to 600pm, more particularly around 300pm. The first chamfer 64 has a width WI, seen in Figure 4, which is such that a ratio of the width WI to the diameter of the through-hole 50 is in the region of 0.2 to 0.5, and more particularly around 0.3 or one third. In the example illustrated in Figure 4, the width W1 is around 100pm. The first chamfer 64 has a depth DI, seen in Figure 5, which is such that a ratio of the depth D1 to a maximal depth DMAX of the through-hole 50 is in the region of 0.4 to 0.6, and more particularly around 0.5.

The first chamfer 64 extends around roughly 1800 of the periphery of the through-hole 50 on the first face 68, although it will be appreciated that in other examples the first chamfer 64 may extend to a greater or lesser degree around the periphery, provided the first chamfer 64 extends only partially about the periphery of the through-hole 50. In some examples, the first chamfer 64 extends around no more than 75%, no more than 60%, or no more than 50% of the periphery of the through-hole 50 on the first face 68.

The second chamfer 66 has a width W2, seen in Figure 6, which is such that a ratio of the width W2 to the diameter of the through-hole 50 is in the region of 0.1 to 0.5, and more particularly around 0.3 or one third. In the example illustrated in Figure 6, the width W2 is around 100nm. The second chamfer 66 has a depth D2, seen in Figure 5, which is such that a ratio of the depth D2 to a maximal depth DMAX of the through-hole 50 is in the region of 0.4 to 0.6, and more particularly around 0.5.

The second chamfer 66 extends around roughly 180° of the periphery of the through-hole on the second face 70, although it will be appreciated that in other examples the second chamfer 66 may extend to a greater or lesser degree around the periphery, provided the second chamfer 66 extends only partially about the periphery of the through-hole 50. In some examples, the second chamfer 66 extends around no more than 75%, no more than 60%, or no more than 50% of the periphery of the through-hole 50 on the second face 70.

As will be appreciated from Figures 4 to 6, the first chamfer 64 is located on a first side 72 of the through-hole 50 relative to an axis B that bisects the through-hole 50 as shown in each of Figures 4 and 6, with the second chamfer 66 located on a second 74 opposite to the first side 72 When utilised in the vacuum cleaner 10 in use, the filter 44 is oriented such that the blade 58 passes firstly over a portion of the periphery of the through-hole 50 where the first chamfer 64 is not located, and then subsequently over the first chamfer 64, when the curved wall 38 moves from the first position of Figure 2 to the second position of Figure 3. In such a manner the first 64 and second 66 chamfers can be considered to define a ramped pathway in the direction in which the filter 44 is wiped by the blade 58.

H

It has been found that provision of the first 64 and second 66 chamfers as described above may aid with removal of dirt and debris, and in particular elongate dirt and debris such as hair, from the filter 44 during wiping of the first face 68 of the filter 44 by the blade 58.

This is illustrated schematically with hair 76 and a wiping direction W shown in Figure 5. In particular, by providing the first 64 and second 66 chamfers there may be less shredding of hair by the periphery of the through-hole 50 compared to an arranged where no chamfer is provided, which may lower the chances of hair becoming clogged in the through-hole 50. Provision of the first 64 and second 66 chamfers may further reduce airflow eddies in a region of the periphery of the through-hole 50 compared to an arrangement where no chamfer is provided and sharp edges occur.

Provision of a chamfer extending fully around a periphery of the through-hole 50 can, in some circumstances, lead to a relatively high failure rate during manufacture. It has been found that provision of the first 64 and second 66 chamfers that extends only partially around a periphery of the through-hole may provide the aforementioned benefits in relation to less shredding of hair, and/or reduction in airflow eddies, as well as less shredding of the blade 58, compared to an arrangement where no chamfer is provided, whilst also enabling manufacturing with a relatively low failure rate compared to an arrangement where a chamfer is provided that extends fully about the periphery of the through-hole 50. Provision of the first 64 and second 66 chamfers that extend only partially around a periphery of the through-hole 50 may also provide an increased strength of filter 44 compared to, for example, an arrangement where a chamfer is provided that extends fully about the periphery of the through-hole 50, as less material may be required to be removed from the filter 44 when creating the chamfer.

Provision of the first 64 and second 66 chamfers may also lower a force required to remove hair from the through-hole 50. A plot of through-hole size versus a force required to remove three strands of hair from the through-hole is illustrated in Figure 7. Here a test method in which three strands of hair are located within a through-hole and pulled

N

vertically downwardly, relative to a plane of the periphery of the through-hole, whilst attached to a force gauge, was utilised Point 80 on the plot is used to indicate the form of through-hole 50 with first 64 and second 66 chamfers previously described. Point 82 represents a 300pm through-hole with no chamfer, point 82 represents a 500pm through-hole with no chamfer, and point 84 represents a 700pm through-hole with no chamfer.

As can be seen from point 80, the through-hole 50 with first 64 and second 66 chamfers described herein generate only 0.21N of force when attempting to remove hair in the manner described above. In contrast, a 300pm through-hole with no chamfer generates around 0.95N of force, a 500pm through-hole with no chamfer generates around 0.33N of force, and a 700tim through-hole with no chamfer generates around 0.04N of force. It will be appreciated that a 700p.m through-hole may be undesirable in the filter 44 of the vacuum cleaner 10 described above, as it may allow passage of relatively large particles of dirt and debris.

The filter 44 described above, with the first 64 and second 66 chamfers, may provide a relatively low generated force, roughly equivalent to that of a roughly 550pm through-20 hole with no chamfer, and hence may provide a good compromise between filtration and ease of hair removal from the filter 44 Whilst the filter 44 has been described above in the context of a particular form of vacuum cleaner 10, it will be appreciated that the form of the vacuum cleaner 10 may vary with the filter 44 still finding utility. For example, a vacuum cleaner 10 in which the secondary cyclonic stage 30 is omitted is envisaged, as indeed are non-cyclonic vacuum cleaners Furthermore, the filter 44 may find utility in other apparatus, for example haircare appliances or air movement devices such as fans or purifiers, with appropriate modification.

Claims

Claims 1. A dirt separator for separating dirt from an airflow, the dirt separator comprising an air inlet, an air outlet, and a filter located between the air inlet and the air outlet, the filter comprising a first face, a second face, and a through-hole extending between the first and second faces, wherein the filter comprises a chamfer extending only partially around a periphery of the through-hole on the first face.
2. A dirt separator as claimed in Claim 1, wherein the chamfer extends around no more than 75%, no more than 60%, or no more than 50% of the periphery of the through-hole on the first face.
3 A dirt separator as claimed in Claim 1 or Claim 2, wherein the through-hole is substantially circular in cross-section, and the chamfer extends around no more than 1800 of the periphery of the through-hole on the first face.
4. A dirt separator as claimed in any preceding claim, wherein the filter comprises a further chamfer extending only partially around a further periphery of the through-hole on the second face.
5. A dirt separator as claimed in Claim 4, wherein the further chamfer extends around no more than 75%, no more than 60%, or no more than 50% of the further periphery of the through-hole on the second face.
6 A dirt separator as claimed in Claim 4 or Claim 5, wherein the through-hole is substantially circular in cross-section, and the further chamfer extends around no more than 1800 of the further periphery of the through-hole on the second face.
7. A dirt separator as claimed in any of Claims 4 to 6, wherein the chamfer and the further chamfer are located on diametrically opposite sides of the respective periphery and further periphery of the through-hole.
A dirt separator as claimed in Claim 7, wherein: the through-hole comprises a central axis extending between the first and second faces; the periphery of the through-hole on the first face comprises a first side and a second side relative to an axis orthogonal to the central axis; the further periphery of the through-hole on the second face comprises a third side corresponding to the first side, and a fourth side corresponding to the second side; the chamfer extends around the first side of the periphery of the through-hole on the first face, and the further chamfer extends around the fourth side of the further periphery of the through-hole on the second face.
9. A dirt separator as claimed in any preceding claim, wherein the dirt separator comprises a cyclonic separator.
10. A dirt separator as claimed in any preceding claim, wherein the dirt separator comprises a wiping mechanism for wiping the first face.
11. A dirt separator as claimed in Claim 10, wherein the wiping mechanism comprises a blade movable relative to the first face from a first position to a second position, and the chamfer is located such that the blade passes over a portion of the periphery of the through-hole that does not comprise the chamfer before passing over the chamfer when moving from the first position to the second position.
12. A dirt separator as claimed in Claim 11, wherein a depth of the chamfer decreases in a direction from the first position to the second position.
13. A dirt separator as claimed in any preceding claim, wherein the through-hole comprises a first width, the chamfer comprises a second width less than the first width, and a ratio of the second width to the first width is in the region of O. Ito 0.5. Vi
14. A dirt separator as claimed in Claim 13, wherein the ratio of the second width to the first width is in the region of 0.3.
15. A dirt separator as claimed in any preceding claim, wherein the through-hole is generally circular in cross-section, and comprises a diameter in the region of 200um to 600um.
16. A dirt separator as claimed in any preceding claim, wherein the through-hole comprises a first maximal depth between the first and second faces, the chamfer comprises a second maximal depth less than the first maximal depth, and a ratio of the second maximal depth to the first maximal depth is in the region of 0.4 to 0.6.
17. A dirt separator as claimed in any preceding claim, wherein the chamfer is formed on the filter by chemical etching.
18. A dirt separator as claimed in any preceding claim, wherein the filter comprises a plurality of through-holes, and a plurality of chamfers each extending only partially about a corresponding periphery of a through-hole on the first face.
19. A filter for a dirt separator, the filter comprising a first face, a second face, and a through-hole extending between the first and second faces, wherein the filter comprises a chamfer extending only partially around a periphery of the through-hole on the first face A vacuum cleaner comprising a dirt separator as claimed in any of Claims Ito 18, or a filter as claimed in Claim 19.