TECHNICAL FIELD

The present invention relates to a dirt separator for a vacuum cleaner and to a vacuum cleaner comprising the dirt separator.

BACKGROUND

Vacuum cleaners rely on a suction generator to generate an airflow, which is used to pick up dirt from a surface to be cleaned. The airflow is passed through one or more separation stages to separate dirt from the airflow before the airflow is ejected from the vacuum cleaner. Pressure losses can occur as the airflow passes through the separation stages, which can reduce performance of the vacuum cleaner and/or increase power consumption of the suction generator.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a dirt separator for a vacuum cleaner, comprising a dirt separation chamber extending along a longitudinal axis from an opening to an outlet, and a filter assembly extending parallel to the longitudinal axis and dividing the dirt separation chamber into a dirt collection chamber upstream of the filter assembly, and an outlet chamber downstream of the filter assembly. The outlet chamber has a cross-sectional area that is substantially constant along a length of the filter assembly.

The dirt collection chamber may have a cross-sectional area that is substantially constant along the length of the filter assembly. The cross-sectional areas of the outlet chamber and dirt collection chamber are in the plane normal to the longitudinal axis.

During use of the dirt separator, suction is generated at the outlet of the dirt separation chamber, causing airflow to flow along an airflow pathway from the opening to the outlet. Since the cross-sectional area of the outlet chamber is substantially constant along its length, the suction is unbalanced along the length of the filter assembly. In particular, suction is greatest at the end of the filter assembly adjacent the outlet and is weakest at the end of the filter assembly adjacent the opening. This then has the advantage that dirt is encouraged to fill the dirt collection chamber in a direction from the outlet (where suction is greatest) to the opening (where suction is weakest). As a result, the dirt separator is able to store a greater quantity of dirt within the dirt collection chamber before emptying is required. This arrangement is by no means intuitive. One would normally ensure that the suction along the filter assembly is balanced to ensure that the filter assembly is loaded evenly with dirt. This would be achieved by ensuring that the cross- sectional area of the outlet chamber gradually decreases in a direction from the outlet to the opening. The cross-sectional area of the outlet chamber would therefore be greatest at the end adjacent the outlet, and smallest at the end adjacent the opening. Having balanced suction along the length of the filter assembly would ensure that dirt collects more evenly on the filter assembly. However, the net result of this is that the dirt collection chamber fills with dirt in a less efficient way. For example, dirt may accumulate more quickly at the end of the dirt collection chamber adjacent the opening, thereby preventing further dirt from being drawn into the dirt separator. Dirt would therefore clog the opening end of the dirt collection chamber even though the remainder of the dirt collection chamber may be relatively empty.

Owing to the location of the opening and the outlet, the airflow moves longitudinally over the surface of the filter assembly. The unbalanced suction encourages more of the airflow to pass through the filter assembly at that end adjacent the outlet. As a result, the airflow may act to scrub the surface of the filter assembly, i.e., dirt which has accumulated at the opening end of the filter assembly may be agitated and driven towards the outlet end by the moving airflow. This then helps keep more of the filter assembly clear of dirt, which improves the performance of the vacuum cleaner and allows the vacuum cleaner to be used for a longer period of time before emptying of the dirt collection chamber is required.

The dirt collection chamber and outlet chamber may be free from features, restrictions or obstructions that increase or decrease a cross-sectional area of the airflow pathway along the length of the filter assembly. This may then better encourage the behaviour described above, i.e., dirt collects within the dirt collection chamber from the end adjacent the outlet to the end adjacent the opening.

A ratio of the cross-sectional areas of the dirt collection chamber to the outlet chamber may be between 0.9 and 1.1 along the length of the filter assembly. As a result, a relatively compact arrangement may be achieved for the dirt separator without adversely impacting performance.

A ratio of the cross-sectional areas of the opening to the outlet may be between 0.9 and 1.1. As a result, a relatively compact arrangement may be achieved without adversely impacting performance. In other vacuum cleaners, the outlet is typically much larger than the opening. However, by ensuring that the ratio of the opening to the outlet is between 0.9 and 1.1, a relatively small outlet may be employed that does not adversely restrict the airflow moving through the dirt separator.

The sum of the cross-sectional areas of the dirt collection chamber and the outlet chamber may be at a minimum along the length of the filter assembly. This increases a velocity of airflow passing through the filter assembly from the dirt collection chamber to the outlet chamber, which may improve filtration performance of the filter assembly. This may also increase the velocity of the airflow moving parallel to the filter assembly to better scrub the filter assembly and encourage dirt to move towards the outlet end of the dirt collection chamber.

A ratio of a length of the dirt separation chamber to a width of the dirt separation chamber may be at least 5. This allows for the filter assembly to be substantially longer than it is wide, which helps to increase an area of a filtration surface of the filter assembly without increasing an overall diameter of the dirt separator. Having a larger filtration surface area can lead to a smaller pressure drop and thus improved suction at the opening, and can also increase a time between necessary replacement or cleaning of the filter assembly. The dirt separation chamber may have a length no less than 150 mm. As a result, a relatively good dirt capacity may be achieved in a dirt separation chamber having a relatively small width or diameter. Additionally, a relatively long filter assembly having a good surface area may be employed, which in turn can improve performance and increase the time between replacement or cleaning.

The dirt separation chamber may have a width, or diameter, no greater than 60 mm. That is, a maximum dimension of the dirt separation chamber in a plane normal to the longitudinal axis may be no greater than 60 mm. More specifically, the dirt separation chamber may have a width in the region of 35-40 mm. This can help to decrease an overall diameter of the vacuum cleaner in which the dirt separator is employed. This could be particularly advantageous in a handheld vacuum cleaner in which size and weight are significant considerations. This may be particularly ergonomic, allowing an outer perimeter of the dirt separator to form a handle for a user to hold the vacuum cleaner during use.

The dirt separation chamber may be substantially cylindrical. This may help to provide smooth, curved walls of the dirt collection chamber and outlet chamber that are substantially free of sudden changes in direction. This may contribute to smoother airflow through the dirt separation chamber.

The filter assembly may comprise a mesh screen and a removable filter medium located downstream of the mesh screen. The mesh screen separates larger dirt and debris entrained in the airflow entering the dirt collection chamber via the opening, and the filter medium filters smaller particles of dirt and dust from the airflow.

The filter medium may be comprised in a removable cartridge having a frame supporting at least one filter medium. This may facilitate removal, cleaning and/or replacement of the filter medium when the filter medium becomes clogged with the dirt and dust so that performance of the dirt separator is reduced. The removable cartridge may comprise more than one type of filter media. For example, a fleece upstream of an electrostatic medium. This may help to increase the filtration performance of the filter assembly.

The mesh screen may be formed from a metal or metal alloy. This may provide a robust surface to protect the filter medium from the larger dirt and debris and that is easy to clean. The mesh screen may have a substantially smooth surface facing the dirt collection chamber, which may help to prevent dirt from catching on the surface.

The filter assembly may be substantially v-shaped or u-shaped in cross-section. The crosssection is in a plane normal to the longitudinal axis. A lowermost portion of the v or u may extend into the outlet chamber. Both shapes provide a greater surface area of the filter assembly for the same length compared to a substantially planar filter assembly. This may improve performance and/or increase the time between replacement or cleaning of the filter assembly. Av-shaped cross-section provides a slightly greater cross-sectional area than a u-shaped cross-section. A u-shaped cross-section provides a smoother shape than a v-shaped cross-section, which may help to prevent dirt from getting caught in the acute angle of the v.

The dirt separator may comprise a valve positioned at the opening, and the valve may be movable between a closed position, in which airflow is prevented from entering the dirt collection chamber via the opening, and a first open position, in which airflow is permitted to enter the dirt collection chamber via the opening. The valve may be moveable to the first open position in response to suction within the dirt separation chamber, and may be moveable to the closed position in response to removal of the suction within the dirt separation chamber. Accordingly, the valve prevents dirt collected in the dirt collection chamber from escaping via the opening when the suction is removed.

The valve may be movable, in response to a user input, from the closed position to a second open position to evacuate dirt collected in the dirt collection chamber. Accordingly, the dirt collection chamber can be emptied via the opening, which negates a need for an additional opening in the dirt separator. This provides a space-efficient construction in which the dirt is evacuated along the air pathway through which it entered the dirt collection chamber. The substantially constant cross-section of the dirt collection chamber can help to ensure that no obstructions impede the evacuation of the dirt from the dirt collection chamber. The first and second open positions may be the same position.

The valve may be biased to the closed position, for example by a biasing assembly or due to a property of a material from which the valve is formed. This may ensure that the valve returns to the closed position when the suction within the dirt separation chamber is removed so that the dirt cannot escape the dirt separation chamber inadvertently via the opening.

The valve may be formed from an elastically deformable material biased to the closed position. This may negate a need for an additional biasing assembly, which may reduce cost and/or simplify the assembly.

The dirt collection chamber may be located on one side of the dirt separator, and the outlet chamber may be located on an opposite side of the dirt separator. The dirt separation chamber may be defined by an outer wall. For example, the outer wall may be substantially cylindrical. The dirt collection chamber may extend between an upstream surface of the filter assembly and a first side of the outer wall, and the outlet chamber may extend between a downstream side of the filter assembly and a second, opposite side of the outer wall. This may provide a space-efficient arrangement, enabling a relatively small outer equivalent diameter of the dirt separator.

According to a second aspect of the present invention, there is provided a vacuum cleaner comprising a main body comprising a dirt separator according to the first aspect and a suction generator for generating an airflow. The suction generator is positioned downstream of the dirt separator and has a rotational axis co-axial with the longitudinal axis of the dirt separator. This provides a space-efficient and ergonomic arrangement, and may enable the vacuum cleaner to have a substantially constant outer cross-sectional profile.

The main body may have a substantially constant cross-section along the longitudinal axis, for example the main body may be substantially cylindrical. This provides a spaceefficient and ergonomic arrangement. The main body may have an outer diameter no greater than 60 mm, for example in the region of 35-40 mm. This may be an ergonomic size to allow the main body to form a handle for a user to grip during use of the vacuum cleaner.

The main body may comprise a battery assembly, which may enable to vacuum cleaner to be used as a cord-free device. The battery assembly may be co-axial with the dirt separator and the suction generator.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples will now be described with reference to the accompanying drawings, in which:

Figure l is a front view of a vacuum cleaner according to an example;

Figure 2 is a cross-sectional side view of the vacuum cleaner of Figure 1;

Figure 3 is an exploded view of the vacuum cleaner of Figure 1;

Figure 4a is a sectional slice through a dirt separator of the vacuum cleaner in the plane A— A indicated in Figure 2;

Figure 4b is a sectional slice through a dirt separator according to a further example;

Figure 5 is a cross-sectional side view through a centre of the dirt separator, wherein a valve of the dirt separator is in a closed position;

Figure 6 is the same cross-sectional view as that of Figure 5, wherein the valve is in an open position;

Figure 7 is the same cross-sectional view as that of Figure 5, wherein the valve is in the open position and dirt is in the dirt separator;

Figure 8 is the same cross-sectional view as that of Figure 5, wherein the valve is in the closed position and dirt is in the dirt separator; Figure 9 is a cross-sectional view of the dirt separator in an emptying configuration;

Figure 10 is the same cross-sectional view as that of Figure 5, wherein the valve is in the closed position and dirt is outside the dirt separator;

Figure 11 is a cross-sectional side view of a portion of a dirt separator according to a further example, wherein a valve of the dirt separator is in a closed position;

Figure 12 is the same cross-sectional side view as that of Figure 11, wherein the valve is in an open position;

Figure 13 is a cross-sectional side view of a portion of a dirt separator according to a still further example;

Figure 14 is a perspective cutaway view of the portion of the dirt separator of Figure 13; Figure 15 is a perspective view of the portion of the dirt separator of Figure 13, wherein a valve of the dirt separator is in a closed position; and

Figure 16 is the same perspective view as that of Figure 15, wherein the valve is in an open position.

DETAILED DESCRIPTION

The example vacuum cleaner 1 of Figures 1-3 comprises a main body 10, an attachment 20 and a cleaner head 30. The cleaner head has an inlet aperture 32 arranged to face a surface to be cleaned by the vacuum cleaner 1, and an outlet 34 fluidly connected to the inlet aperture 32. The attachment 20 in this example is a tool, but in other examples may be a wand or other suitable attachment type. In any event, the attachment 20 comprises a duct 21 between a first end 22 and a second, opposite end 24 of the attachment 20. When assembled, as shown in Figures 1 and 2, the cleaner head 30 is removably attached to a first end 22 of the attachment 20, and a second end 24 of the attachment 20 is removably attached to the main body 10 such that an airflow pathway is formed from the cleaner head 30, through the attachment 20, to the main body 10.

When attached to the main body 10, the attachment 20 is arranged co-axially with a central longitudinal axis 2 of the main body 10. In this example, the main body 10 and the attachment 20 are generally cylindrical in shape, with each having an outer housing 12, 23 of a substantially constant outer diameter. The outer housing 12 of the main body 10 surrounds a suction generator 14 to generate an airflow along the airflow pathway, and a battery assembly 16 to power the suction generator 14. It will be appreciated that in other examples, the main body 10 may be provided with a power supply unit, to replace or supplement the battery assembly 16, for connection to a mains power outlet.

The main body 10 comprises a dirt separator 100 upstream of the suction generator 14. The dirt separator 100 is shown in more detail and in various configurations in Figures 4- 10. As with the outer housing 12, the dirt separator 100 is also cylindrical in shape and has a substantially constant outer diameter.

The dirt separator 100 comprises an opening 102 at an interface between the main body 10 and the attachment 20. The opening 102 serves as both an air inlet and a dirt outlet of the dirt separator 100. When serving as an air inlet, the opening 102 permits the airflow generated by the suction generator 14 to pass into the dirt separator 100 from the duct 21 in a direction parallel to the longitudinal axis 2 of the main body 10 (which is co-axial with a longitudinal axis of the dirt separator 100). The dirt separator 100 also comprises an air outlet 106 fluidly connected to the suction generator 14, to permit airflow to exit the dirt separator 100. In this example, when assembled, a ratio of the cross-sectional areas of the opening 102 and the outlet 106 is substantially 1.

In this example, the dirt separator 100 comprises a frame 104 that extends parallel to the longitudinal axis 2 of the main body 10. The frame 104 is fixed at a first end to the outer housing 12 of the main body 10. A second opposite end 105 of the frame 104 partially defines the opening 102 of the dirt separator 100.

The frame 104 supports electrical terminals 17 and electrical wires 18. The electrical terminals 17 are located at the second end 105 of the frame 104, and the electrical wires 18 extend along the length of the frame 104 from the main body 10 to the electrical terminals 17. The electrical terminals 17 mate with corresponding terminals (not shown) of the attachment 20 to transfer electrical power from the main body 10 to the cleaner head 30. A filter assembly 120 is attached to the frame 104. The filter assembly 120 is configured to separate dirt D from dirt-laden airflow received via the opening 102, and comprises two filtration layers 122, 124 for doing so, as best shown in Figure 4a. It will be appreciated that in other examples, the filter assembly 120 may comprise a different number of filtration layers.

The filter assembly 120 comprises a mesh or screen 122 fixedly attached to the frame 104 and a filter cartridge removable attached to the frame 104. In this example, the mesh or screen 122 is the uppermost filtration layer 122 shown in Figure 4a, and is formed of a metal.

The filter cartridge is located downstream of the mesh 122 and comprises a filter frame and filter media 124 held by the frame. The mesh 122 protects the filter media 124 from impacts by debris in the dirt separator 100. The filter media 124 is the lowermost layer 124 shown in Figure 4a. Being removable allows the filtration media 124 to be replaced and/or washed to restore filtration performance of the filter assembly 120. Although not shown in Figure 4a, in some examples the filter media 124 has a plurality of filtration layers of differing filtration properties. For example, the filter media 124 may comprise a layer formed from fleece upon a layer formed from an electrostatic medium.

The mesh 122 is substantially curved, as viewed in a plane normal to the longitudinal axis 2 (Figure 4a), and the filter media 124 is substantially planar. It will be appreciated that in other examples, the mesh 122 may be, for example, v-shaped or planar.

Figure 4b shows an example of an alternative filter assembly 120b in the dirt separator 100. The alternative filter assembly 120b is very similar to the filter assembly 120 except that in this example the filter media 124b is substantially curved. Providing a substantially planar filter media 124, as shown in Figure 4a, allows a thicker lower-most filtration layer 124 to be employed within the same overall diameter of the dirt separator 100 compared to a curved filter media 124b, as shown in Figure 4b, which can increase the filtration performance of the filter assembly 100. Conversely, providing a curved filter media 124b increases the surface area of the filter media 124b compared to the surface area of the filter media 124, which may also provide filtration benefits such as increasing a time between required replacement or cleaning of the filter media 124b. References herein to the filter assembly 120 may equally apply to the alternative filter assembly 120b.

The filter assembly 120 is elongate in a direction parallel to the longitudinal axis 2. Accordingly, airflow enters the dirt separator 100 in a direction parallel to the filter assembly 120 so that the airflow scrubs the mesh 122 of the filter assembly 120 to help attenuate accumulation of dirt D on the filter assembly 120.

The filter assembly 120 forms a wall of a dirt collection chamber 108. The dirt collection chamber 108 receives dirt-laden airflow via the opening 102 during vacuum cleaning and fills up with dirt D separated from the dirt-laden airflow by the filter assembly 120. The dirt collection chamber 108 is elongate in shape and extends between the opening 102 at one end, and the outer housing 12 of the main body 10 at an opposite end. The dirt collection chamber 108 extends alongside the filter assembly 120 and has a substantially constant cross-sectional profile along the length of the filter assembly 120, as viewed in a plane normal to the longitudinal axis 2. The elongate shape of the dirt collection chamber 108 allows for a larger volume for a given diameter of the dirt separator 100.

The filter assembly 120 separates the dirt collection chamber 308 from an outlet chamber 103 downstream of the filter assembly 120. The outlet chamber fluidly connects the filter assembly 120 to the air outlet 106. The dirt separator therefore comprises an upper longitudinal portion comprising the dirt collection chamber 108 and a lower longitudinal portion comprising the outlet chamber 103.

The outlet chamber 103 also has a constant cross-sectional area along the length of the filter assembly 120. In this example, the ratio of the cross-sectional areas of the dirt collection chamber 108 to the outlet chamber 103 is substantially 1. Since the cross- sectional area of the outlet chamber 103 is substantially constant along its length, suction is unbalanced along the length of the filter assembly 120. In particular, suction is greatest at the end of the filter assembly 120 adjacent the outlet 106 and is weakest at the end of the filter assembly 120 adjacent the opening 102. Dirt D is therefore encouraged to fill the dirt collection chamber 108 in a direction from the outlet 106 (where suction is greatest) to the opening 102 (where suction is weakest). As a result, the dirt collection chamber 108 is able to store a greater quantity of dirt D within the dirt collection chamber 108 before emptying is required.

The dirt separator 100 comprises a tubular outer wall, orbin, 130 extending along a length of the dirt separator 100 and surrounding the frame 104, the filter assembly 106 and the valve 110. The outer wall 130 defines a cylindrical dirt separation chamber 101 of the dirt separator 100, the chamber 101 comprising the dirt collection chamber 108 and the outlet chamber 103. In this example, the dirt separation chamber 101 is around 8 times longer than it is wide. The dirt collection chamber 108 is therefore defined along one side by the outer wall 114 and along an opposite side by the frame 104 and the filter assembly 106.

A valve 110 is connected to the second end 105 of the frame 104 such that the valve 110 is positioned at the opening 102. The valve 110 is movable between a closed position (as shown in Figures 5, 8 and 10), a first open position (as shown in Figures 6 and 7) in response to suction within the dirt separator 100 generated by the suction generator 14, and a second open position (as shown in Figure 9). The valve 110 is movable between the different positions about a pivot axis 112 that is normal to the longitudinal axis 2. In the present example, the valve is formed of an elastically deformable material, such as rubber, and is configured to pivot about a hinge at the base of the valve 110.

In the closed position, the valve 110 obstructs the opening 102 such that dirt D is prevented from escaping the dirt collection chamber 108 via the opening 102. The valve 110 abuts a lip 134 of the outer wall 130 when in the closed position, as best shown in Figures 5 and 8. The lip 134 acts to help maintain the valve 110 in the closed position, particularly when dirt D in the dirt collection chamber 108 rests against the valve, as shown in Figure 8. In the closed position, an outer perimeter of the valve 110 forms a seal with the frame 104 and the outer wall 130 at the opening 102. This seal prevents dirt D from inadvertently escaping the dirt collection chamber 108.

The valve 110 moves from the closed position to the first open position in response to suction within the dirt collection chamber 108. In the first open position, the opening 102 is unobstructed by the valve 110, thereby enabling dirt-laden airflow to be drawn from the inlet aperture 32 of the attachment, through the duct 21 and into the dirt separator 100 via the opening 102. In moving to the first open position, the valve 110 pivots about the pivot axis 112 in a first direction towards the interior of the dirt collection chamber 108. The valve 110 then provides a smooth surface for the airflow, which can help to prevent dirt within the airflow from catching on the valve 110 as it passes into the dirt collection chamber 108.

As described below in more detail, the valve 110 moves from the closed position to the second open position during emptying of the dirt separator 100. In the second open position, the opening 102 is unobstructed by the valve 110, thereby enabling dirt D in the dirt collection chamber 108 to exit the dirt separator 100, for example under gravity, via the opening 102. In moving to the second position, the valve 110 pivots about the pivot axis 112 in a second opposite direction to that of the first open position. The valve 110 then provides a smooth surface to help prevent the dirt D from catching on the valve 110 as it passes out of the dirt collection chamber 108

The valve 110 is biased to the closed position such that, in the absence of force acting on the valve 110, the valve 110 remains or returns to the closed position.

The dirt separator 100 comprises a well 109 located downstream of the opening 102, between the valve 100 and the dirt collection chamber 108. The well 109 has a greater cross-sectional area than the dirt collection chamber 108. When the dirt separator 100 is not in use, dirt D collected in the dirt collection chamber 108 may fall under gravity and come to rest against the valve 110, as shown in Figure 8. In examples of a dirt separator that do not have a well 109, the accumulation of dirt D on one side of the valve 100 may hinder movement of the valve 110 to the first open position. Accordingly, a relatively large force may be required to move the valve 110 against the weight of the dirt D to the first open position. If there is too much dirt D in the dirt collection chamber 108, the dirt D may cause the valve 110 to become stuck in the closed position, or at least prevent the valve 110 from moving fully to the first open position under the suction generated by the suction generator 14. The well 109 provides a larger space behind the valve 110 to accommodate dirt D that falls under gravity. This can reduce the force required to move the valve 110 to the first open position, and therefore help to prevent the valve 110 from getting stuck in the closed position.

Build-up of dirt D in the dirt collection chamber 108 can negatively impact the pick-up performance of the vacuum cleaner 1. Performance can be at least partially restored by emptying the dirt D from the dirt collection chamber 108. Accordingly, the dirt separator 100 is arranged to allow a user to perform a simple dirt emptying sequence to empty dirt D from the dirt collection chamber 108, as will now be described.

The dirt emptying sequence is performed with the attachment 20 detached from the main body 10 and the suction generator 14 powered off.

The outer wall 130 is movable relative to the valve 110 and the frame 104 between a first position (as shown in Figures 5-8) and a second position (as shown in Figure 9). Movement of the outer wall 130 between the first and second positions is in a direction parallel to the longitudinal axis 2 of the main body 10. In the first position, the outer wall 130 surrounds all of the frame of the main body 10. A majority of the outer wall 130 is therefore located downstream of the valve 100 when the outer wall 130 is in the first position. A small portion, or cuff, of the outer wall 130 extends upstream of the valve 110 when the outer wall 130 is in the first position, and serves to protect the electrical terminals 17 and to receive and form an attachment with the end 24 of the attachment 20. In the second position, a majority of the outer wall 130 is located upstream of the valve 100 such that the opening 132 is further from the main body 10 than when in the first position.

The outer wall 130 comprises a pair of ridges 136 protruding inwardly from an inner surface 131 of the outer wall 130 (as best shown in Figures 4a and 4b). The ridges 136 extend longitudinally along opposite sides of the outer wall 130. The pair of ridges 136 act upon the valve 110 to move the valve 110 from the closed position to the second open position (as shown in Figure 9) as the outer wall 130 is moved from the first position to the second position. In the second open position, the opening 102 is unobstructed by the valve 110. Accordingly, movement of the outer wall 130 from the first position to the second position opens the opening 102 such that dirt D in the dirt collection chamber 108 can be evacuated under gravity via the opening 102. It will be appreciated that in other examples alternative actuator elements may be employed to move the valve 110 to the second open position.

The dirt separator 100 comprises a plunger 116 attached to the outer wall 130 and positioned in the dirt collection chamber 108. In this example, the plunger 116 protrudes from the inner surface 131 of the outer wall 130 into the dirt collection chamber 108 along a plane normal to the longitudinal axis 2 of the main body 10. The plunger 116 and the outer wall 130 are movable as a single body between the first and second position.

When the outer wall 130 is in the first position, the plunger 116 is adjacent the main body 10. As the outer wall 130 moves towards the second position, the plunger 116 pushes dirt D in the dirt collection chamber towards and/or past the valve 110.

To assist in pushing as much of the dirt D in the dirt collection chamber 108 as possible, the plunger 116 comprises a resilient wiper 118 (as best shown in Figure 3) at a periphery of the plunger 116. The wiper 118 is configured to wipe a surface of the mesh 122 of the filter assembly 120 as the outer wall 130 is moved between the first and second positions. The wiper 118 dislodges dirt D from the mesh 122 to better restore filtration performance of the filter assembly 120. In a first stage of an emptying sequence, a user applies a force to the outer wall 130 to move the outer wall 130 and the plunger 116 from the first position to the second position, as shown in Figure 9. Accordingly, dirt D in the dirt collection chamber 108 is pushed towards the valve 110. Movement of the outer wall 130 from the first position towards the second position causes the pair of ridges 136 to push the valve 110 to the second open position so that the dirt D can be pushed and/or fall under gravity past the valve 110.

In a second stage of the emptying sequence, a user applies a force to the outer wall 130 to move the outer wall 130 and the plunger 116 from the second position to the first position, as shown in Figure 10. Due to the nature of dirt D that is typically collected during use of a vacuum cleaner, the dirt D tends to gather together as a single clump, for example due to entangled hair or fibres. This can cause the dirt clump D to remain within the outer wall 130 even after it has passed the valve 110 during the first stage of the emptying sequence.

Accordingly, the dirt separator 100 is arranged such that, during the second stage of the emptying sequence, the valve 110 is moved from the second open position to the closed position so that the dirt clump D is pushed out of the opening 132 by the valve 110. In this example, the pair of ridges 136 have a length that is shorter than a length of travel of the outer wall 130 between the first and second positions. Consequently, as the outer wall 130 nears the second position, the ridges 136 pass the valve 110 and so stop acting upon the valve 110. The valve 110 therefore returns to the closed position under the biasing force. As the outer wall 130 is then moved from the second position to the first position, the ridges 136 again act upon the valve 110. However, the force applied by the ridges 136 is insufficient to move the valve 110 to the first open position, such that the valve 110 remains in the closed position during the second stage of the emptying sequence.

The frame 104 comprises slots 111 adjacent to the outer wall 130, as best shown in Figures 4a and 4b. The slots 111 extend parallel to the longitudinal axis 2 of the main body 10 and engage with the ridges 136 on the inner surface 131 of the outer wall 130. The ridges 136 are slidable in the slots 111 to constrain rotational movement of the outer wall 130 relative to the frame 104.

Although not shown in this example, the dirt separator 100 may comprise a biasing assembly to bias the outer wall 130, and thus the plunger 116, towards the first position. The biasing assembly may comprise a spring disposed in each of the slots 111 and attached to the respective ridges 136. In biasing the outer wall 130 and the plunger 116 towards the first position, the biasing assembly assists in ensuring the outer wall 130 returns fully to the first position.

In this example, the user grips an outer surface of the outer wall 130 to perform the emptying sequence. It will be appreciated that in other examples, the dirt separator 100 may comprise a handle, knob, collar or other suitable element connected directly or indirectly to the outer wall 130 for a user to grip and cause the outer wall 130 to slide parallel to the longitudinal axis 2 relative to the frame 104.

Figures 11 and 12 show a portion of a dirt separator 200 according to a further example. In this further example, the dirt separator 200 is for use in a vacuum cleaner having the same features as the vacuum cleaner 1 shown in Figure 1. The portion is a distal end of the dirt separator 200 relative to the main body 10. The dirt separator 200 differs from the dirt separator 100 described with reference to Figures 1-10 in the arrangement of the valve 210. Other features of the dirt separator 200 are substantially identical to those of the dirt separator 100 and have the same reference numbers, but increased by 100. In this further example, the first and second open positions of the valve 210 are the same position, and will be referred to herein as the open position.

The valve 210 is formed from a rigid material and is biased to the closed position (as shown in Figure 11) by a spring 214. The spring 214 is attached to the frame 204 and is located in the well 209. In order to prevent dirt D in the dirt collection chamber 208 from entering the well 209 and potentially damaging the spring 214, the valve 210 is v-shaped, having a first arm 217 and a second arm 219. The first arm 217 of the valve 210 is pivotally attached to the frame 204 by a pivot pin 211. The valve 210 therefore pivots about the pivot axis 212 between the open position and the closed position. The second arm 219 of the valve extends from the opposite end of the first arm 217 to that of the pivot pin 211. When the valve 210 is in the open position, the first arm 217 defines part of the airflow pathway along which airflow enters the dirt separator 200, and the second arm 219 is located in the well 209 and therefore out of the airflow pathway. When the valve is 210 is in the closed position, the first arm 217 contacts the lip 234 of the outer wall 230 and forms a seal with the outer wall 230, and the second arm extends between the outer wall 230 and the frame 204 to prevent dirt D in the dirt collection chamber 208 from entering the well 209 (as shown in Figure 11).

The valve 210 is movable from the closed position to the open position (as shown in Figure 12) in response to suction within the dirt separator 200 generated by the suction generator 14. Suction in the dirt collection chamber 208 causes a drop in pressure in the dirt collection chamber 208 such that ambient air outside the dirt separator 200 applies a force on the valve 210 to overcome the biasing force of the spring 214 to move the valve 210 to the open position.

The valve 210 is also movable to the open position to permit emptying of dirt D from the dirt collection chamber 208 (as shown in Figure 12). Ridges on the inner surface of the outer wall 230 (as described above with reference to Figures 1-10) cooperate with the valve 210 as the outer wall 230 is moved towards the second position. The ridges push the valve 210 downwards to the open position. Removal of force by the ridges upon the valve 210 allows the spring 214 to move the valve 210 back to the closed position.

During movement from the closed position to the open position, the v-shaped nature of the valve 210 means that the second arm 219 slides relative to dirt D resting against the arm 219, rather than pushes against the dirt D. This can reduce the chance of the valve 210 becoming stuck in the closed position and reduce a moment about the pivot axis 212 that is required to open the valve 210. Figures 13 to 16 show a portion of a dirt separator 300 according to a still further example. In this still further example, the dirt separator 300 is for use in a vacuum cleaner having the same features as the vacuum cleaner 1 shown in Figure 1. The portion is a distal end of the dirt separator 300 relative to the main body 10. The dirt separator 300 differs from the dirt separator 100 described with reference to Figures 1-10 and the dirt separator 200 described with reference to Figures 11 and 12 in the arrangement of the valve 310. Other features of the dirt separator 300 are substantially identical to those of the dirt separator 100 and have the same reference numbers, but increased by 200.

The dirt separator 300 comprises a valve 310 rotatable about a pivot axis, or valve axis, 312 by a motor 315 between a closed position and an open position. The pivot axis 312 is co-axial with the longitudinal axis 2 of the main body 10, and therefore parallel to a direction of flow entering the dirt separator 300 via the opening 302. It will be appreciated that in other examples, the pivot axis 312 may not be co-axial with the longitudinal axis 2.

In the closed position (as shown in Figures 13-15), the valve 310 is configured to obstruct the opening 302, and therefore the airflow pathway. The valve 310 therefore prevents dirt D from escaping the dirt collection chamber 308 via the opening 302 when in the closed position.

In the open position (as shown in Figure 16), the opening 302 is unobstructed by the valve 310. The valve 310 may be moved to the open position when the suction generator is powered on to enable dirt-laden airflow to be drawn into the dirt separator 300 via the opening 302. Alternatively, the valve 310 may be moved to the open position when the suction generator is powered off to enable dirt D within the dirt collection chamber 308 to be emptied via the opening 302.

In this example, the valve 310 is in the form of a radial disc having a diameter substantially equal to an inner diameter of the outer wall 330. The valve 310 has an aperture 340, in this case a sector of almost 180 degrees, cut out of it. In the open position, the aperture 340 is aligned with the opening 302 such that the valve 310 does not obstruct the opening 302. In the closed position, the aperture 340 is misaligned with the opening 302 such that the valve 310 obstructs the opening 302. As with the valve 210 described with reference to Figures 11 and 12, during movement from the closed position to the open position, the valve 310 slides relative to dirt D resting against the valve 310, rather than pushing against the dirt D. This can reduce the chance of the valve 310 becoming stuck in the closed position and reduce the torque required from the motor 315 to open the valve 310.

In this example, the valve 310 is driven by the motor 315 via a pair of gears 344,346. This then allows the position of the motor 315 to be offset from the pivot axis 312 (i.e., the rotational axis of the motor 315 may be offset from the pivot axis 312).

In this example, the dirt separator 300 comprises a passage 348 extending from the opening 302 to the dirt collection chamber 308 and the motor is positioned alongside the passage 348. The passage is comprised in the upper longitudinal portion of the dirt separator 300. A cross-sectional area of the passage 348 is equal to a cross-sectional area of the opening 302 and the dirt collection chamber 308, to provide a smooth air pathway to the dirt collection chamber 308.

The motor 315 is contained in a motor chamber 350 to prevent dirt D affecting performance of the motor 315. The motor chamber 350 is comprised in the lower longitudinal portion of the dirt separator 300, longitudinally adjacent to the passage 348.

In this example, electrical wires (not shown) are mounted to the frame 304 and extend along a length of the frame 304. The electrical wires deliver electrical power from the battery assembly 16 to the motor 315.

In this example, the vacuum cleaner 1 comprises a control system (not shown) arranged to receive a signal indicative of a user desire to empty the dirt collection chamber 308 and, in response to receiving the signal, cause the motor 315 to move the valve 310 to the open position. The control system comprises a switch located on the outer housing 12 of the main body 10 that is actuable by a user to indicate a desire to empty the dirt collection chamber 308. Actuation of the switch causes the control system to generate the signal. Accordingly, the valve 310 is movable to the closed position to evacuate dirt D from the dirt collection chamber 308.

The control system is also arranged to cause the motor 315 to move the valve 310 between the open and closed positions in response to a signal indicative of a user desire to power on and off the vacuum cleaner 1. In response to the signal indicative of a user desire to power on the vacuum cleaner 1, the control system is arranged to cause the motor 315 to move the valve 310 to the open position after the suction generator 14 is powered on. In response to the signal indicative of a user desire to power off the vacuum cleaner 1, the control system is arranged to cause the motor 315 to move the valve 310 to the closed position before the suction generator 14 is powered off. This ensures that the suction generator 14 is always powered on when the valve 310 is in the open position so that dirt D does not inadvertently escape the dirt collection chamber 308 during vacuum cleaning.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, the dirt separators 200, 300 may comprise any of the features of the dirt separator 100 described with reference to Figures 1-10. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.