CN118251165A - Dust separator - Google Patents

Abstract

A dust separator (18) for separating dust from an airflow includes an air inlet (40), an air outlet (54), and a filter (44) between the air inlet and the air outlet. The filter includes a first face (68), a second face (70), and a through-hole (50) extending between the first face and the second face. The filter includes a chamfer (64, 66) extending only partially around the perimeter of the through-hole on the first face.

Description

Dust separator

Technical Field

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

Background technique

Vacuum cleaners typically use a dust separator to separate dust from the airflow carried by the vacuum cleaner in use. Some dust separators may utilize filters to assist in dust separation.

Summary of the invention

According to a first aspect of the present invention, a dust separator for separating dust from an air flow is provided, the dust 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 surface, a second surface and a through hole extending between the first surface and the second surface, wherein the filter comprises a chamfer extending only partially around the periphery of the through hole on the first surface.

Providing a filter including a chamfer that extends only partially around the perimeter of the through-hole on the first face may make it easier to remove elongated debris, such as hair, from the filter while also providing a filter that may be manufactured with a relatively low failure rate.

In particular, it has been found that providing a filter having a through hole with sharp edges (e.g. without chamfers) within a dust separator of a vacuum cleaner can result in the through hole being clogged with elongated dust particles or debris such as hair, which elongated hair dust particles prove to be relatively difficult to remove from the filter. This is particularly the case when the filter is cleaned by wiping, for example, using a blade or other material in a direction substantially parallel to the periphery of the through hole. Indeed, it has been found that when such wiping is performed, the sharp edges of the periphery of the through hole may shred or cut the hair cuticle, causing the hair to become stuck in the through hole and requiring the user to manually remove the hair. This can be unhygienic and therefore undesirable for the user.

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

However, in some cases, providing a chamfer that extends completely around the perimeter of the through hole can result in a relatively high failure rate during manufacturing. It has been found that providing a chamfer that extends only partially around the perimeter of the through hole on the first side can provide the above-mentioned benefits related to less hair shredding, lower hair removal forces and/or reduction in airflow eddy compared to an arrangement where no chamfer is provided, while also being able to be manufactured with a relatively low failure rate compared to an arrangement where a chamfer is provided that extends completely around the perimeter of the through hole on the first side. Providing a chamfer that extends only partially around the perimeter of the through hole can provide increased filter strength compared to, for example, an arrangement where a chamfer is provided that extends completely around the perimeter of the through hole on the first side, as less material needs to be removed from the filter when the chamfer is created.

The chamfer may extend around no more than 75%, no more than 60%, or no more than 50% of the circumference of the through hole on the first side. It has been found that the extent of the chamfer may be reduced while still providing the aforementioned advantages of less hair shredding, lower hair removal forces, reduction in airflow vortices, increased strength, and/or lower failure rates during manufacturing. The chamfer may extend around 50% of the circumference of the through hole on the first side. The through hole may be substantially circular in cross-section, and the chamfer may extend around no more than 180° of the circumference of the through hole on the first side.

The filter may include a further chamfer extending only partially around the further periphery of the through-hole on the second side. This may result in less chopping of hair around the further periphery of the through-hole when cleaning the first side filter by wiping, for example, compared to an arrangement where no chamfer is provided around the further periphery of the through-hole. It has also been found that providing a chamfer around the further periphery of the through-hole may result in less force required to remove hair from the through-hole of the filter, compared to an arrangement where no chamfer is provided, for example. Providing a chamfer may further reduce airflow eddies in the further periphery region of the through-hole, for example, compared to an arrangement where no chamfer is provided and a sharp edge is present.

However, in some cases, providing a chamfer that extends completely around the other periphery of the through hole may result in a relatively high failure rate during manufacturing. It has been found that providing a chamfer that extends only partially around the other periphery of the through hole on the second side can provide the above-mentioned benefits related to less hair chopping, lower hair removal force and/or reduced airflow vortex compared to an arrangement where no chamfer is provided, while also being able to be manufactured with a relatively low failure rate compared to an arrangement where a chamfer is provided that extends completely around the other periphery of the through hole on the second side. Providing a chamfer that extends only partially around the other periphery of the through hole can provide increased filter strength compared to, for example, an arrangement where a chamfer is provided that extends completely around the other periphery of the through hole on the second side, because less material needs to be removed from the filter when the chamfer is produced. The further chamfer may extend no more than 75%, no more than 60% or no more than 50% around the other periphery of the through hole on the second side. It has been found that the extent of the further chamfer can be reduced while still providing the aforementioned advantages of less hair chopping, lower hair removal force, reduction in airflow vortex, increased strength and/or a lower failure rate during manufacturing. The further chamfer may extend around 50% of the other periphery of the through hole on the second side. The through hole may be substantially circular in cross-section, and the further chamfer may extend no more than 180° around another periphery of the through hole on the second face.

The chamfer and the further chamfer may be located on radially opposite sides of the respective periphery and the further periphery of the through-hole, for example the chamfer extends around a first lower side of the periphery of the through-hole on the first side and the further chamfer extends around a second upper side of the further periphery on the second side. This may define a generally diagonal path through the through-hole, for example from a first side of the filter to a second side of the filter, which may help reduce the shredding of hair when wiping the filter and may help reduce the force required to remove hair from the through-hole.

The through hole may include a central axis extending between the first face and the second face, a periphery of the through hole on the first face includes a first side and a second side relative to an axis orthogonal to the central axis, another periphery of the through hole on the second face includes a third side corresponding to the first side and a fourth side corresponding to the second side, a chamfer extends around the first side of the periphery of the through hole on the first face, and another chamfer extends around the fourth side of the other periphery of the through hole on the second face. In this way, the chamfer and the other chamfer do not overlap each other when viewed in a cross section taken along the central axis.

The dust separator may include a cyclonic separator, such as a separator configured to separate dust by cyclonic separation. The dust separator may include a housing, an air inlet is formed in the housing, and the housing is configured to generate a spiral airflow in the housing during use. The housing may include a substantially cylindrical overall form. The filter may be positioned in the housing so that a substantially spiral airflow is generated between the housing and the filter during use. For example, the filter may define a curved surface in the housing. The first face of the filter may define a curved surface in the housing.

The filter may be of substantially cylindrical form, for example such that the first face comprises the outer surface of the filter and the second face comprises the inner surface of the filter. In this way, the through-holes may define an airflow path through the filter in use, and dust or debris larger than the through-holes may not pass through the through-holes. The first face may comprise the upstream face of the filter and the second face may comprise the downstream face of the filter.

The dust separator may include a wiping mechanism for wiping the first side. Dust or debris may thus be removed from the first side of the filter, e.g. without requiring a user to manually remove the dust or debris using hands or a cloth or the like.

The wiping mechanism may include a blade movable from a first position to a second position relative to the first face, for example in a direction parallel to the central axis of the filter, and the chamfer may be positioned such that when moving from the first position to the second position, the blade passes over a peripheral portion of the through-hole that does not include the chamfer before passing over the chamfer. Such a position of the chamfer may reduce the force required to remove dust or debris (e.g., hair) from the through-hole and may facilitate removal of hair from the filter by the wiping mechanism.

The dust separator may include a dust outlet that is 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.

The depth of the chamfer may decrease in the direction from the first position to the second position. This may help remove dust or debris, such as hair, from the through hole. The depth of another chamfer may increase in the direction from the first position to the second position.

The through hole may include a first width, such as a diameter, the chamfer may include a second width that is less than the first width, and the ratio of the second width to the first width may be in the range of 0.1 to 0.5. Such a ratio may facilitate the removal of dust or debris (e.g., hair) from the through hole, for example by reducing the force required to remove dust or debris (e.g., hair) from the through hole, and may facilitate the removal of hair from the filter by a wiping mechanism. The ratio of the second width to the first width is about 0.3, for example about one-third.

The through hole may be substantially circular in cross section and may have a diameter in the range of 200 μm to 600 μm, for example about 300 μm. Such a through hole size may prevent relatively large dust or debris from passing through the through hole and may, for example, provide a filter that is particularly useful in a vacuum cleaner. The second width may be in the range of 80 μm to 150 μm, for example about 100 μm.

The through hole may include a first maximum depth between the first and second faces, the chamfer may include a second maximum depth that is less than the first maximum depth, and the ratio of the second maximum depth to the first maximum depth may be in the range of 0.4 to 0.6, such as about 0.5. This may provide a filter with sufficient structural integrity while facilitating the removal of dust or debris (e.g., hair) from the through hole. Another chamfer may include a third maximum depth that is less than the first maximum depth, and the ratio of the third maximum depth to the first maximum depth may be in the range of 0.4 to 0.6, such as about 0.5. The second maximum depth and the third maximum depth may be substantially the same.

A chamfer may be formed on the filter by chemical etching.Another chamfer may be formed on the filter by chemical etching.

The filter may include a plurality of through holes and a plurality of chamfers, each chamfer extending only partially around a respective periphery of the through holes on the first face. The filter may include a plurality of further chamfers extending only partially around a respective periphery of the through holes on the second face.

According to a second aspect of the present invention, there is provided a filter for a dust separator, the filter comprising a first face, a second face and a through hole extending between the first face and the second face, 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 the dust separator according to the first aspect of the present invention and/or the filter according to the second aspect of the present invention.

The vacuum cleaner may comprise a handheld unit comprising a dust separator and a suction motor for generating an air flow from an air inlet of the dust separator to an air outlet of the dust separator. The vacuum cleaner may comprise a cleaning head detachably attached to the handheld unit, for example directly or via one or more intermediate tubes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a perspective view of a vacuum cleaner;

FIG2 is a side view of the handheld unit of the vacuum cleaner of FIG1 in a first configuration;

FIG3 is a side view of the handheld unit of FIG2 in a second configuration;

FIG4 is a schematic diagram of a first side of a filter of the handheld unit of FIG2 ;

FIG5 is an enlarged cross-sectional view of the filter of FIG4;

FIG6 is a schematic diagram of a second side of the filter of FIG4 ;

FIG7 is a second schematic diagram of the first side of the filter;

Fig. 8 is a cross-sectional view taken along line C-C of Fig. 7;

Fig. 9 is a cross-sectional view taken along line D-D of Fig. 7;

Fig. 10 is a cross-sectional view taken along line E-E of Fig. 7; and

11 is a graph of through-hole size versus force for an illustrative filter.

Detailed ways

1 shows a vacuum cleaner 10, which includes a handheld unit 12, a cleaning head 14 and an elongated tube 16. The handheld unit 12 is releasably attached to the cleaning head 14 via the elongated tube 16, and in an alternative configuration, the handheld unit 12 may be directly attached to the cleaning head 14.

The handheld unit 12 comprises a dust separator 18 and a main body 20. The main body 20 is shaped to define a handle 22 and to house a battery pack 24 and a suction motor 26.

The dust separator 18 includes a primary cyclone stage 28 and a secondary cyclone stage 30. The primary cyclone stage 28 includes a separation chamber 32 defined by a lower wall 34, an upper wall 36, and a curved wall 38 between the lower wall 34 and the upper wall 36, such that the separation chamber 32 is substantially cylindrical. An opening in the lower wall 34 defines an air inlet 40 of the dust separator 18. The lower wall 34 is pivotally connected to the curved wall 38 so that the lower wall 34 can move relative to the curved wall 38 to define a dust outlet that can remove dust and debris from the separation chamber 32 of the dust separator 18.

The separation chamber 32 houses a filter 44 in the form of a shroud. The filter 44 is arranged in a substantially cylindrical manner within the separation chamber 32 and includes a plurality of through holes 50, which will be described in more detail below.

The secondary cyclone stage 30 includes a plurality of relatively small cyclone bodies 52 and a fine dust collection chamber 46 extending through the separation chamber 32. The lower wall 34 of the separation chamber 32 also serves as a housing for the fine dust collection chamber 46.

During operation of the vacuum cleaner 10, the battery pack 24 provides electrical energy to the suction motor 26 to generate an airflow through the vacuum cleaner 10. A brush bar (not shown) within the cleaning head 14 agitates the surface to be cleaned so that dust is entrained in the airflow through the vacuum cleaner 10. The dust-laden air enters the dust separator 18 through the air inlet 40 and flows within the separation chamber 32 in a spiral manner.

As the airflow flows within the separation chamber 32, larger dust and debris are removed from the airflow due to the centrifugal force. After the larger dust and debris are separated from the airflow in the separation chamber, the airflow passes through the filter 44 and enters the secondary cyclone stage 30. The small cyclone body 52 is able to separate any finer dust that can pass through the filter 44, and the fine dust enters the fine dust collection chamber 46. The cleaned airflow leaves the secondary cyclone stage 30 through the air outlet 54 of the small cyclone body 52, and thus leaves the dust separator 18. Although not shown, in some examples, the airflow passes through the pre-motor filter, the suction motor 26, and the post-motor filter 27 before being discharged into the atmosphere.

As the airflow moves within the separation chamber 32 and through the through holes 50 of the filter 44, dust and debris may be trapped in or on the filter 44. To facilitate cleaning of the filter 44, the dust separator 18 includes a wiping mechanism 56. The wiping mechanism includes a blade 58, a track 60, and an actuator 62. In some examples, the blade 58 includes 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 can move relative to the small cyclone body 52 along the track 60, for example, the curved wall 38 includes an engagement feature (not shown) for sliding engagement with the track 60. The actuator 62 is fixedly attached to the outer surface of the curved wall 38 of the separation chamber 32, so that the force applied by the user to the actuator 62 moves the curved wall 38 along the track 60.

Specifically, when a user applies a force to the actuator 62 in the direction indicated by the arrow A in FIG. 2 , i.e., in a direction parallel to the central axis of the filter 44 and the separation chamber 32 and away from the handle 22, the curved wall 38 can be moved along the track 60 from the first position shown in FIG. 2 to the second position shown in FIG. 3 . As the curved wall 38 moves along the track 60, the blade 58 moves relative to the filter 44 and contacts the filter 44, so that when moving from the first position of FIG. 2 to the second position of FIG. 3 , the blade 58 wipes the outer surface of the filter 44. In this way, dust and debris adhering to the filter 44 can be removed from the filter 44 by the blade 58. As shown in FIG. 3 , actuating the actuator 62 in this manner also moves the lower wall 34 relative to the curved wall 38, for example, opening the separation chamber 32, so that dust and debris are discharged from the separation chamber 32 and the fine dust collection chamber 46.

While it has been found that wiping the filter 44 in this manner helps to remove dust and debris from the surface of the filter 44, it has also been found that in some cases, elongated dust and debris, such as hair, remain on the filter 44 despite the action of the blade 58. Specifically, elongated dust and debris, such as hair, can become trapped in the through holes 50 of the filter 44.

To aid in the removal of dust and debris, the filter 44 includes first and second chamfers 64, 66 located around the perimeter of each respective through hole 50, a single through hole 50 being schematically shown in each of Figures 4 to 10. The first and second chamfers 64, 66 are formed on the filter by a chemical etching process.

The filter 44 has a first face 68 as an outer/upstream face and a second face 70 as an inner/downstream face, with the through holes 50 extending between the first face 68 and the second face 70 .

As shown in Fig. 4, the first chamfer 64 extends only partially around the perimeter of the through hole 50 on the first face 68 of the filter 44, and the first chamfer 64 extends around the lower half of the perimeter. The through hole 50 is substantially circular in cross section, and the first chamfer 64 has a substantially U-shaped profile when viewed in Fig. 4, and the second chamfer 66 has a substantially inverted U-shaped profile when viewed in Fig. 6.

The diameter of the through hole 50 is in the range of 200 μm to 600 μm, more specifically about 300 μm. As shown in FIG. 4 , the first chamfer 64 has a width W1, and the ratio of the width W1 to the diameter of the through hole 50 is in the range of 0.2 to 0.5, more specifically about 0.3 or one third. In the example shown in FIG. 4 , the width W1 is about 100 μm. As shown in FIG. 5 , the first chamfer 64 has a depth D1, so that the ratio of the depth D1 to the maximum depth DMAX of the through hole 50 is in the range of 0.4 to 0.6, more specifically about 0.5.

The first chamfer 64 extends approximately 180° around the perimeter of the through hole 50 on the first side 68, although it will be appreciated that in other examples, the first chamfer 64 may extend around the perimeter to a greater or lesser extent, as long as the first chamfer 64 only partially extends around the perimeter 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 perimeter of the through hole 50 on the first side 68.

As shown in FIG6 , the second chamfer 66 has a width W2, and the ratio of the width W2 to the diameter of the through hole 50 is in the range of 0.1 to 0.5, more specifically about 0.3 or one third. In the example shown in FIG6 , the width W2 is about 100 μm. As shown in FIG5 , the second chamfer 66 has a depth D2, so that the ratio of the depth D2 to the maximum depth DMAX of the through hole 50 is in the range of 0.4 to 0.6, more specifically about 0.5.

The second chamfer 66 extends approximately 180° around the perimeter of the through hole 50 on the second face 70, although it will be appreciated that in other examples, the second chamfer 66 may extend around the perimeter to a greater or lesser extent, as long as the second chamfer 66 only partially extends around the perimeter 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 perimeter of the through hole 50 on the second face 70.

As can be appreciated from FIGS. 4 to 6 , the first chamfer 64 is located on a first side 72 of the through hole 50 relative to the axis B that bisects the through hole 50, and the second chamfer 66 is located on a second side 74 opposite the first side 72, as shown in FIGS. 4 and 6 . When used with the vacuum cleaner 10 in use, the filter 44 is oriented so that when the curved wall 38 moves from the first position of FIG. 2 to the second position of FIG. 3 , the blade 58 first passes over the peripheral portion of the through hole 50 where the first chamfer 64 is not provided, and then passes over the first chamfer 64. In this manner, the first chamfer 64 and the second chamfer 66 can be considered to define an inclined path in the direction in which the blade 58 wipes the filter 44.

It has been found that providing the first chamfer 64 and the second chamfer 66 as described above can help remove dust and debris, particularly elongated dust and debris, such as hair, from the filter 44 during the process of the blade 58 wiping the first face 68 of the filter 44. This is schematically illustrated by the hair 76 and the wiping direction W shown in FIG5. In particular, by providing the first chamfer 64 and the second chamfer 66, the periphery of the through hole 50 is less likely to chop hair than an arrangement where no chamfer is provided, which can reduce the likelihood of hair clogging the through hole 50. Providing the first chamfer 64 and the second chamfer 66 can further reduce airflow vortices in the area around the through hole 50 compared to an arrangement where no chamfer is provided and sharp edges are present.

In some cases, providing a chamfer that extends completely around the perimeter of the through-hole 50 can result in a relatively high failure rate during manufacturing. It has been found that providing a first chamfer 64 and a second chamfer 66 that extend only partially around the perimeter of the through-hole can provide the above-mentioned benefits related to less hair cutting and/or reduced airflow vortex and less cutting by the blade 58 compared to an arrangement where no chamfer is provided, while also being able to be manufactured with a relatively low failure rate compared to an arrangement where a chamfer is provided that extends completely around the perimeter of the through-hole 50. Providing a first chamfer 64 and a second chamfer 66 that extend only partially around the perimeter of the through-hole 50 can also provide increased strength to the filter 44 compared to, for example, an arrangement where a chamfer is provided that extends completely around the perimeter of the through-hole 50, because less material needs to be removed from the filter 44 when the chamfer is created.

The provision of the first chamfer 64 and the second chamfer 66 can also reduce the force required to remove hair from the through hole 50. Figure 7 shows a graph of through hole size versus the force required to remove three strands of hair from the through hole. A test method was used here in which three strands of hair were located within the through hole and pulled vertically downward relative to the plane of the perimeter of the through hole while attached to a force gauge.

Point 80 on the graph is used to represent the form of via 50 having the aforementioned first chamfer 64 and second chamfer 66. Point 82 represents a 300 μm via without chamfer, point 83 represents a 500 μm via without chamfer, and point 84 represents a 700 μm via without chamfer.

As can be seen from point 80, when attempting to remove hair in the manner described above, the through hole 50 described herein with the first chamfer 64 and the second chamfer 66 only generates a force of 0.21 N. In comparison, a 300 μm through hole without chamfers generates a force of approximately 0.95 N, a 500 μm through hole without chamfers generates a force of approximately 0.33 N, and a 700 μm through hole without chamfers generates a force of approximately 0.04 N. It should be appreciated that in the filter 44 of the vacuum cleaner 10 described above, a 700 μm through hole may not be ideal because it may allow relatively large dust and debris particles to pass through.

The above filter 44 with the first chamfer 64 and the second chamfer 66 can provide a relatively low generation force, substantially equivalent to the generation force of a through hole of about 550 μm without chamfers, and thus can provide a good compromise between filtering and ease of removing hair from the filter 44.

Although the filter 44 has been described above in a particular form of vacuum cleaner 10, it should be understood that the form of the vacuum cleaner 10 may vary with the use of the filter 44. For example, a vacuum cleaner 10 omitting the secondary cyclone stage 30 is contemplated, as is a non-cyclonic vacuum cleaner. Furthermore, the filter 44 may be used in other devices, such as a hair care appliance or an air moving device, such as a fan or purifier, with appropriate modifications.

Claims (20)

1. A dust separator for separating dust from an air flow, the dust 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 surface, a second surface and a through hole extending between the first surface and the second surface, wherein the filter comprises a chamfer extending only partially around the periphery of the through hole on the first surface. 2. The dust separator according to claim 1, wherein the chamfer extends no more than 75%, no more than 60% or no more than 50% around the circumference of the through hole on the first face. 3. A dust separator according to claim 1 or 2, wherein the cross-section of the through hole is substantially circular, and the chamfer extends no more than 180° around the periphery of the through hole on the first face. 4. A dust separator according to any one of the preceding claims, wherein the filter comprises a further chamfer extending only partially around a further periphery of the through hole on the second face. 5. The dust separator according to claim 4, wherein the further chamfer extends no more than 75%, no more than 60% or no more than 50% around the further periphery of the through hole on the second face. 6. The dust separator according to claim 4 or 5, wherein the cross section of the through hole is substantially circular, and the further chamfer extends for no more than 180° around the further periphery of the through hole on the second face. 7. The dust separator according to any one of claims 4 to 6, wherein the chamfer and the further chamfer are located at radially opposite sides of the respective periphery and the further periphery of the through hole. 8. The dust separator according to claim 7, wherein: The through hole includes a central axis extending between the first and second faces; The periphery of the through hole on the first face includes a first side and a second side relative to an axis orthogonal to the central axis; Another periphery of the through hole on the second face includes a third side corresponding to the first side and a fourth side corresponding to the second side; The chamfer extends around a first side of a perimeter of the through hole on the first face; and The other chamfer extends around a fourth side of another periphery of the through hole on the second face. 9. A dust separator according to any preceding claim, wherein the dust separator comprises a cyclone separator. 10. A dust separator according to any preceding claim, wherein the dust separator comprises a wiping mechanism for wiping the first face. 11. A dust separator according to claim 10, wherein the wiping mechanism includes a blade capable of moving from a first position to a second position relative to the first surface, and the chamfer is positioned so that when moving from the first position to the second position, the blade passes over the portion of the periphery of the through hole that does not include the chamfer before passing over the chamfer. 12. The dust separator according to claim 11, wherein a depth of the chamfer decreases in a direction from the first position to the second position. 13. The dust separator according to any one of the preceding claims, wherein the through hole comprises a first width, the chamfer comprises a second width smaller than the first width, and a ratio of the second width to the first width is in the range of 0.1 to 0.5. 14. The dust separator of claim 13, wherein a ratio of the second width to the first width is about 0.3. 15. A dust separator according to any one of the preceding claims, wherein the through-holes are substantially circular in cross-section and have a diameter in the range of 200 to 600 μm. 16. A dust separator according to any one of the preceding claims, wherein the through hole comprises a first maximum depth between the first face and the second face, the chamfer comprises a second maximum depth that is less than the first maximum depth, and a ratio of the second maximum depth to the first maximum depth is in the range of 0.4 to 0.6. 17. A dust separator according to any one of the preceding claims, wherein the chamfer is formed on the filter by chemical etching. 18. A dust separator according to any one of the preceding claims, wherein the filter comprises a plurality of through holes and a plurality of chamfers, each chamfer extending only partially around a respective periphery of the through hole on the first face. 19. A filter for a dust separator, the filter comprising a first face, a second face and a through hole extending between the first face and the second face, wherein the filter comprises a chamfer extending only partially around a perimeter of the through hole on the first face. 20. A vacuum cleaner comprising a dust separator according to any one of claims 1 to 18 or a filter according to claim 19.