Patent Description:
A vacuum cleaning appliance or, more simply, "vacuum cleaner", typically comprises a main body which is equipped with a suction motor, a dust separator, and a cleaner head connected to the dust separator usually by a separable coupling. The dust separator is the main mechanism by which the vacuum cleaner removes dirt and debris from the airflow through the machine, and this applies whether the dust separator relies on a cyclonic separation system or otherwise.

Although dust separators are generally very efficient at removing dirt and debris from the airflow, fine particles remain in the airflow that exits the dust separator and travels towards the suction motor. It is important that the suction motor is protected from these fine particles as they can be potentially damaging to some of its components. It is also important to make the exhaust airflow that is discharged from the vacuum cleaner as clean as possible, and to this end it is desirable to conform to HEPA standard filtration, as would be well-known to those skilled in this technical field.

Typically, a vacuum cleaner includes two filters: a first filter, also called a "pre-motor filter" or "pre-filter" which is located in the airflow through the machine downstream of the dust separator but upstream of the suction motor; and a second filter, also called a "post-motor filter" or "post-filter" that is located in the airflow downstream of the suction motor, before the airflow exhausts from the machine. Incorporating two filters into a vacuum cleaner can challenge packaging constraints, as well as making the machine larger and heavier. What is more, although it is usually recommended that both filters are washed frequently, filter washing typically is carried out less often than directed, which may be due, at least partly, to the additional inconvenience in having to find and remove two filters from the machine.

It has been attempted to combine pre- and post-filters into a single package to address packaging issues and to make filter removal and replacement more convenient. However, incorporating such combined filter packages in a vacuum cleaner in a way that is readily accessible, space efficient, ergonomic and yet unobtrusive can present a challenge.

<CIT> discloses a method and structure for removing a filter from a vacuum cleaner where the filter apparatus has a frame and a filter. The filter can be removed from the vacuum cleaner without removing the lid.

<CIT> discloses a structure of an air filter for an air conditioner where the filter has a receiving groove and is engaged using a push and pop-up manner.

According to a first aspect of the invention, there is provided a filter arrangement for a vacuum cleaning appliance, comprising: a filter enclosure having an enclosure opening; a filter configured to be received through the enclosure opening into the filter enclosure in an insertion direction; and retention means operable between latched and unlatched states for releasably retaining the filter in the filter enclosure, wherein the filter includes an actuation portion configured to operate the retention means, wherein the actuation portion is moveable between at least first and second positions and is biased towards the second position, wherein, when the filter is in the filter enclosure, movement of the actuation portion in the insertion direction from the first position to a depressed position transitions the retention means to the unlatched state, whereinafter the actuation portion is moved to the second position in which at least a part of the actuation portion is elevated above the enclosure opening.

An arrangement according to the invention advantageously permits easy removal of the filter from the filter enclosure. By simply moving the actuation portion in the insertion direction from the first to the depressed position, the retention means is transitioned to the unlatched state, and the actuation portion is biased into the second position. The required movement of the actuation portion is therefore straightforward and intuitive. In this elevated second position, a user is able to gain a purchase on, or grasp, the actuation portion, for removal. The filter can therefore be extracted from the filter enclosure in a small number of simple steps, when washing or other maintenance activities are required, for example.

Optionally, when the filter is in the filter enclosure, movement of the actuation portion in the insertion direction from the second position to the depressed position transitions the retention means to the latched state, whereinafter the actuation portion may be moved into the first position. Advantageously, the movement for transitioning the retention means to the latched state may therefore be the same as the movement for transitioning the retention means to the unlatched state. This further increases the simplicity of the arrangement, and the ease with which a filter can be inserted and removed from the filter enclosure.

Optionally substantially all, or the whole, of the actuation portion is elevated above the enclosure opening when the actuation portion is in the second position. The actuation portion may be spaced apart from the enclosure opening when the actuation portion is in the second position. In this way, the user is able to grip the sides and/or the base of the actuation portion for removal, increasing the ease of handling of the actuation portion.

The actuation portion may close the enclosure opening when in the first position. This feature has the advantage that the actuation portion has a dual-function, both sealing the filter in the filter enclosure and causing latching or unlatching of the retention means. This additionally reduces the number of component parts, increasing the simplicity of the arrangement and the ease of use. The first position may correspond to a stowed position, while the second position may correspond to an elevated, or removal position. An upper surface of the actuation portion may be substantially level with the enclosure opening when the actuation portion is in the first position.

The filter may further include a filter body, and the actuation portion may be movable relative to the filter body. Advantageously, this means that the filter body itself does not need to be moved to transition the retention means to an unlatched or to a latched state, and that this unlatching or latching can be effected by a separate component. The first and second positions may be positions of the actuation portion relative to the filter body.

The actuation portion may be biased away from and/or relative to the filter body, towards the second position. This feature has the advantage that the actuation portion is advantageously urged away from the filter body and into the second position when the retention means transitions to the unlatched state, or into the first position when the retention means transitions to the latched state, without input being required from the user. In addition, the actuation portion is advantageously urged into the second position irrespective of whether the filter is in the filter enclosure. Such an arrangement is relatively simple, and does not require the filter to be in position in the filter enclosure before the actuation portion is biased into the second position.

The actuation portion may be biased by a biasing means. The biasing means may be positioned intermediate the filter body and the actuation portion. The biasing means optionally comprises a torsion spring, a tension spring, a compression spring, a magnetic device or an elastomeric member, or a combination thereof.

Movement of the actuation portion relative to the filter body may cause operation of the retention means, such that the retention means transitions to the unlatched or to the latched state.

The retention means may include a first latching mechanism associated with the actuation portion and a second latching mechanism associated with the filter body. Advantageously, the provision of a latching mechanism for each of the actuation portion and the filter body means that the filter is securely retained in the filter enclosure when the retention means is in the latched state, and provides a level of redundancy. The latched state of the retention means may be a state in which each of the first and second latching mechanisms is in a respective latched state, while the unlatched state of the retention means may be a state in which each of the first and second latching mechanisms is in a respective unlatched state. The provision of two latching mechanisms may additionally mean that there are one or more intermediate states between the latched state and the unlatched state of the retention means, when the first latching mechanism is unlatched and the second is latched, for example.

The first latching mechanism may include a two-state latching mechanism which is activated by movement of the actuation portion relative to the filter body between the first position and the depressed position. The two-state latching mechanism may comprise a protrusion, or activation pin, and a receiving portion configured to be activated by and/or to receive the activation pin. The protrusion and receiving portion may be mounted to a respective one of the actuation portion and the filter enclosure. As such, movement of the actuation portion relative to the filter body from the first position to the depressed position may advantageously cause activation of the first latching mechanism, disengaging the actuation portion from the filter enclosure.

The second latching mechanism may include a latch member carried on the filter body which is engageable with the filter enclosure. Movement of the actuation portion relative to the filter body between the first position and second position may cause movement of the latch member. Conveniently, the latch member may be a latch bolt.

For example, movement of the actuation portion relative to the filter body from the first position to the second position may cause the latch member to move out of engagement with the filter enclosure, and may cause retraction of the latch member towards the filter body. Movement of the actuation portion relative to the filter body from the second position to the first position may cause extension or movement of the latch member into engagement with the filter enclosure, and may cause the latch member to move away from the filter body. Movement of the actuation portion relative to the filter body from the first position and/or the second position to the depressed position optionally causes extension of the latch member into engagement with the filter enclosure.

Optionally, the latch member is biased out of engagement with the filter enclosure. Advantageously, this means that the latch member is biased into a position in which the second latching mechanism is in an unlatched state. In this way, once any external force applied to the latching mechanism by way of the actuation portion has been removed, the latch member retracts and the filter body can be removed from the filter enclosure without resistance.

Movement of the latch member may be in a direction that is transverse to the movement of the actuation portion. Optionally, movement of the latch member is in a direction that is substantially perpendicular to the movement of the actuation portion. Movement of the latch member may be in a direction that is transverse to the movement of the actuation portion in the insertion direction.

The filter may comprise alignment means configured to guide the movement of the actuation portion relative to the filter body. Advantageously, this means that the movement and orientation of the actuation portion relative to the filter body is controlled, and that the actuation portion is only permitted to move relative to the filter body in the insertion direction and a direction opposite thereto. Undesirable relative translational or rotational movement between the two parts is therefore mitigated against. The alignment means may comprise one or more protrusions and one or more openings, each of the one or more protrusions being received by a corresponding one of the one or more openings. The one or more protrusions may be elongate members or rods, and each of the openings may be complementary elongate openings, wherein each member and/or opening optionally extends in the insertion direction.

The actuation portion may have a plan profile that substantially corresponds to a plan profile of the filter body. Such an arrangement is advantageously relatively compact, while providing an actuation portion having a relatively large surface area for depression. The actuation portion may comprise a plate-shaped member. Optionally, the actuation portion is a closure plate or lid.

The actuation portion may be suspended, or moveably suspended, relative to the filter body by a load-equalising mechanism. The load-equalising mechanism may be configured to maintain the orientation of the actuation portion relative to the filter body during movement of the actuation portion. Such a load-equalising mechanism advantageously permits a user to apply a load at any point on the actuation portion and for the entire actuation portion to move uniformly in the insertion direction, maintaining the orientation of the actuation portion relative to the filter body. The load-equalising mechanism therefore increases the ease of use of the filter arrangement, and the ease of removal of the filter from the filter enclosure, since a user is not required to apply pressure at a specific point on the actuation portion.

The load-equalising mechanism may comprise a pair of torque arms, a first torque arm of the pair optionally being transverse to a second torque arm of the pair. As such, the torque arms may spread, or equalise, an applied load in different directions. The first torque arm may be perpendicular to the second torque arm.

The first and second torque arms may each be pivotably mounted to at least one of the actuation portion and the filter body, and may each be in sliding communication with at least one of the actuation portion and the filter body. The actuation portion or the filter body may comprise a pair of elongate tracks, each elongate track being configured to receive a respective one of the first torque arm and the second torque arm.

Optionally, the filter and the filter enclosure define a keyway arrangement such that the filter may only be received into the filter enclosure in a single orientation. Such an arrangement increases the ease of insertion of the filter into the filter enclosure, guarding against incorrect insertion and ensuring that the filter is positioned in the filter enclosure in the orientation in which it can operate successfully.

Optionally, the enclosure opening has a central longitudinal axis substantially perpendicular to the insertion direction, the keyway arrangement being offset from the central longitudinal axis at the enclosure opening when the filter is in the filter enclosure. Optionally, the keyway arrangement comprises at least one protrusion and at least one recess, each protrusion optionally being received by a respective recess when the filter is received into the filter enclosure. Each protrusion may be an elongate rib, and each recess may be an elongate channel, wherein each elongate rib and each elongate channel optionally extends in the insertion direction. The at least one recess may extend from the enclosure opening into the filter enclosure, wherein a width of each recess in a direction substantially perpendicular to the insertion direction may be at a maximum at a first end of the recess corresponding to the enclosure opening. Each recess may be tapered at a first end of the recess corresponding to the enclosure opening. Such a feature further increases the ease with which the filter can be inserted into the filter enclosure.

The filter may comprise an angled side, or side wall, the angled side being at a transverse angle to the insertion direction when the filter is in the filter enclosure. The filter enclosure may comprise a flexible side wall biased towards the filter to support the filter in the filter enclosure. The flexible side wall may engage a side, or side wall, of the filter when the filter is received into the filter enclosure. The filter may comprise a filter body, and the filter body and the filter enclosure may define the keyway arrangement.

Optionally, the filter comprises a first filter and a second filter. The first filter and the second filter may be annular about a common axis and the first and second filters are typically concentrically arranged. Advantageously, in such a configuration the first and second filters take a compact arrangement, reducing the space required by the filters in the vacuum cleaning appliance, freeing up space for other components and increasing the ease with which the filters can be packaged and housed in the appliance.

The first filter is optionally positioned radially outward of the second filter, in a direction perpendicular to the common axis. Typically, the first filter is a pre-motor filter and the second filter is a post-motor filter. When the pre-motor filter is positioned radially outwardly of the post-motor filter, this has the advantage that the filter that is required to filter the more heavily dust and dirt-laden air has the larger surface area, increasing the effectiveness of the vacuum cleaning appliance and increasing the time that elapses before the filters need washing or maintenance.

The first and second filters may be housed within and/or configured to engage with the actuation means. The first and second filters are optionally moveable relative to the actuation means, to disengage the first and second filters therefrom. The first and second filters may be housed within and/or configured to engage with the filter body. The first and second filters are optionally moveable relative to the filter body, to disengage the first and second filters therefrom.

The first and second filters may be coupled so as to be moveable as a single unit. The first and second filters may be coupled to a gripping means, for gripping the first and second filters during movement thereof. Such a feature increases the ease of handling and manipulation of the first and second filters, during maintenance activities for example.

The first filter may overlap with the second filter in a direction parallel to the common axis. The cross sectional shape of one or both of the first and second filters in a plane perpendicular to the common axis may be one of circular, elliptical or obround.

In another aspect of the invention, there is provided a vacuum cleaning appliance comprising a filter arrangement in accordance with a previous aspect of the invention.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/ or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/ or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/ or incorporate any feature of any other claim although not originally claimed in that manner.

The above and other aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:.

In the drawings, like features are denoted by like reference signs.

A specific embodiment of the invention will now be described in which numerous features will be discussed in detail in order to provide a thorough understanding of the inventive concept as defined in the appended claims. However, it will be apparent to the skilled person that the invention may be put in to effect without the specific details and that in some instances, well known methods, techniques and structures have not been described in detail in order not to obscure the invention unnecessarily. Moreover, references in the following description to "left", "right", "front", "rear" and any other terms having an implied orientation, such as "vertical" and "horizontal" are not intended to be limiting, and refer only to the orientation of the features as shown in the accompanying drawings.

<FIG> shows a vacuum cleaning appliance or vacuum cleaner <NUM> comprising a main body <NUM>, a suction motor <NUM>, a dirt and dust separator <NUM>, a filter arrangement <NUM> having a filter <NUM>, and a cleaner head <NUM> connected to the dust separator <NUM>. In use, the suction motor <NUM> draws dirt-laden air from a surface to be cleaned through the cleaner head <NUM> and into the dirt and dust separator <NUM>. The dirt and dust separator <NUM> separates dirt and debris from the dirt-laden air drawn in through the cleaner head <NUM>, before the air is expelled into the filter <NUM> for removal of smaller dirt and dust particles. The filter <NUM> itself comprises a first, pre-motor filter 18a (shown in <FIG>) and a second, post-motor filter 18b (not shown in <FIG>), situated upstream and downstream of the suction motor <NUM>, respectively. After passing through the pre-motor filter 18a, the suction motor <NUM> and the post-motor filter 18b, the cleaned air is then expelled from the vacuum cleaner <NUM> into the atmosphere.

The dirt and dust separator <NUM> shown in this example is a cyclonic separating unit, but it will be appreciated by the skilled person that the separator <NUM> may take any one of a number of suitable forms, and that the cyclonic separating unit <NUM> may be replaced with an alternative separating unit or combination of separating units. In addition, in the described arrangement, the vacuum cleaner <NUM> takes the form of a robot vacuum cleaner. However, it will be appreciated that the filter arrangement <NUM> described herein may be used with other types of vacuum cleaners such as, for example, upright or stick vacuum cleaners.

Turning to <FIG>, the filter arrangement <NUM> will now be described. The filter arrangement <NUM> comprises a filter enclosure <NUM> extending into the main body <NUM> of the vacuum cleaner <NUM> and defining an enclosure opening <NUM> at an upper surface 12a of the main body <NUM>, such that the upper surface 12a and enclosure opening <NUM> lie in substantially the same plane. The filter <NUM> is configured to be received through the enclosure opening <NUM> and into the filter enclosure <NUM> in an insertion direction I (shown in <FIG>), which, in the described arrangement, is substantially vertical. It will be appreciated that the insertion direction I will depend on the specific arrangement of the filter <NUM> and filter enclosure <NUM> and may therefore take another orientation. A removal direction of the filter <NUM> is substantially opposite to the insertion direction I.

In use of the vacuum cleaner <NUM>, the filter <NUM> is housed and retained in the filter enclosure <NUM>. However, it is recommended that pre- and post-motor filters 18a, 18b are washed at regular intervals, to remove dirt and dust particles that have built up on their component parts over time, and it is desirable for the filter <NUM> to be removable from the filter enclosure <NUM> for this purpose. To this end, the filter arrangement <NUM> also comprises a retention means <NUM> operable between latched and unlatched states for releasably retaining the filter <NUM> in the filter enclosure <NUM>, such that the filter <NUM> may be held in the filter enclosure <NUM>, or released for handling by a user when washing or other maintenance activities are necessary.

In the described arrangement, the filter <NUM> includes a filter body <NUM> and an actuation portion <NUM> mounted to the filter body <NUM>. The actuation portion <NUM> is configured to operate the retention means <NUM>, and is moveable relative to the filter body <NUM> between at least a relatively low first position and a relatively high second position. The actuation portion <NUM> takes the form of a closure plate and closes the enclosure opening <NUM> when in the first position, sitting substantially flush, or level, with the upper surface 12a of the main body <NUM>. The closure plate <NUM> is in this first position during normal operation of the vacuum cleaner <NUM>.

When the filter <NUM> is in the filter enclosure <NUM>, movement of the actuation portion <NUM> in the insertion direction I from the first position to a depressed position transitions the retention means <NUM> to the unlatched state so that the closure plate <NUM> is biased towards the second position. Upon this transition, the closure plate <NUM> is urged, or moved, into the second position. In this second position, the closure plate <NUM> is elevated above, and is spaced apart from the enclosure opening <NUM>. From this position, subsequent movement of the actuation portion <NUM> in the insertion direction I to the depressed position transitions the retention means <NUM> to the latched state, and the closure plate is urged, or moved, into the first position.

While the actuation portion <NUM> is described herein as being a separate part to the filter body <NUM>, the skilled person will appreciate that the actuation portion <NUM> may alternatively be integral with the filter body <NUM>. In other words, the filter body <NUM> may itself be configured to operate the retention means <NUM> and can be moveable between at least first and second positions, in the manner described above.

The filter body <NUM> and closure plate <NUM> will now be described in more detail, with reference to <FIG>.

The filter body <NUM> is substantially rectangular in plan profile, comprising front, rear, left-hand and right-hand sides <NUM>, <NUM>, <NUM>, <NUM>. The pre- and post-motor filter 18a, 18b are each housed within the filter body <NUM>, and the front <NUM> and rear <NUM> sides of the filter body <NUM> curve inwardly, towards one another, following the shape of the filters. To permit air flowing out of the cyclonic separating unit <NUM> to enter the filter body <NUM> for filtering by the pre- and post-motor filters 18a, 18b, the rear <NUM> of the filter body <NUM> defines a filter inlet opening <NUM>.

The left-hand side <NUM> of the filter body <NUM> is generally vertical, and is substantially parallel with the insertion direction I when the filter body <NUM> is in place in the filter enclosure <NUM>. In contrast, the right-hand side <NUM> of the filter body <NUM> is angled, sloping inwardly towards the left-hand side wall. As such, the right-hand side <NUM> is at a transverse angle to the insertion direction I when the filter <NUM> is in the filter enclosure <NUM>. In practice, the sloping right-hand side <NUM> of the filter body <NUM> advantageously assists with smooth insertion of the filter <NUM> into the filter enclosure <NUM>, guarding against the filter body <NUM> catching, or snagging, against an edge of the enclosure <NUM>.

The closure plate <NUM> has a plan profile that broadly corresponds to the rectangular plan profile of the filter body <NUM>, and is elevated above and spaced apart from the filter body <NUM> in both the first and second position. In particular, the closure plate <NUM> is suspended directly above the filter body <NUM> by way of both a load-equalising mechanism <NUM> and a biasing means <NUM> positioned intermediate the filter body <NUM> and closure plate <NUM>. The load-equalising mechanism <NUM> is configured to maintain the orientation of the closure plate <NUM> relative to the filter body <NUM> during movement of the closure plate <NUM>, while the primary purpose of the biasing means is to bias the closure plate <NUM> away from the filter body <NUM>.

The biasing means is in the form of a compression spring <NUM>, coupled at a lower end to an upper side of the filter body <NUM> and at an upper end to an underside of the closure plate <NUM>, opposing the filter body <NUM>. The compression spring <NUM> urges the closure plate <NUM> into the second position, in which the spring <NUM> is neither in tension nor compression. The closure plate <NUM> has a central longitudinal axis A, substantially perpendicular to the insertion direction I when the filter <NUM> is in the filter enclosure <NUM> and, in the depicted arrangement, the spring <NUM> is positioned along this central longitudinal axis A, towards a front end of the closure plate <NUM>. It will be appreciated that the spring may take any one of a number of suitable positions, and that the arrangement may alternatively comprise two springs each positioned either end of the closure plate <NUM>, or four springs positioned at respective corners of the closure plate <NUM>, for example.

As shown in <FIG>, the load-equalising mechanism <NUM> takes the form of a pair of torque arms 42a, 42b mounted to the upper side of the filter body <NUM>. A first torque arm 42a of the pair is longer than, and substantially perpendicular to, a second torque arm 42b of the pair, such that a central longitudinal axis of an elongate portion of the first torque arm 42a is perpendicular to a central longitudinal axis of a corresponding elongate portion of the second torque arm 42b. The first torque arm 42a extends from front to rear along the length of the filter body <NUM>, while the second torque arm 42b extends across the filter body <NUM> from left to right. The elongate portion of each torque arm is received by a complimentary mount <NUM> on the filter body <NUM>, and is permitted to rotate about its central longitudinal axis, in a hinge-type arrangement. While each torque arm 42a, 42b is therefore free to pivot in its respective mount <NUM>, the connection between the torque arm and the mount <NUM> is relatively tight, to avoid undesirable relative translational movement, or 'rattling', therebetween.

The underside of the closure plate <NUM>, opposing the upper side of the filter body <NUM>, is provided with four elongate tracks (not shown). The ends of each torque arm 42a, 42b remote from their respective mounts <NUM> are received in respective tracks, such that the torque arms 42a, 42b are in sliding communication with the closure plate <NUM>. It will be apparent to the skilled person that the sliding direction of the first torque arm 42a relative to the closure plate <NUM> is substantially perpendicular to the sliding direction of the second torque arm 42b relative to the closure plate <NUM>.

In practice, when pressure is applied at any point on the closure plate <NUM> to move the closure plate <NUM> towards the filter body <NUM>, the torque bars 42a, 42b ensure that the entire closure plate <NUM> moves in a uniform manner. In other words, in the event that a user presses down on a corner of the closure plate <NUM> when it is in position in the filter enclosure <NUM>, the entire closure plate <NUM> moves downwardly towards the filter body <NUM>, and the attitude of the closure plate <NUM> relative to the filter body <NUM> is maintained.

The load-equalising mechanism <NUM> may itself also have a biasing function, to bias the closure plate <NUM> away from the filter body <NUM>. For example, a spring may be coupled between each torque arm 42a, 42b and the respective mount <NUM>, biasing the ends of the torque arm that are remote from the mount <NUM> upwardly, away from the filter body <NUM>.

Other arrangements are envisaged in which the torque arms 42a, 42b take other positions or orientations relative to the filter body <NUM>. For example, the torque arms 42a, 42b may alternatively be mounted to the closure plate <NUM>, and in sliding communication with the filter body <NUM>. The load-equalising mechanism <NUM> could alternatively take another form, provided that the means is capable of maintaining the orientation of the closure plate <NUM> relative to the filter body <NUM> during movement of the closure plate <NUM> towards and away from the filter body <NUM>. For example, the load-equalising mechanism may be in the form of a scissor mechanism <NUM>', as shown in <FIG>. In this arrangement, two scissor arms <NUM>'a, <NUM>'b are provided, each being slidably and pivotably mounted to a respective one of the closure plate <NUM>' and filter body <NUM>', and being pivotably connected to the other.

To further guide the movement of the closure plate <NUM> relative to the filter body <NUM>, the filter <NUM> additionally comprises alignment means. The alignment means takes the form of a number of rods <NUM> mounted to the closure plate <NUM>, and complimentary elongate openings <NUM> in the filter body <NUM>. In the depicted arrangement, four rods <NUM> are provided, each extending from a respective corner of the underside of the closure plate <NUM> towards the filter body <NUM>. Similarly, four elongate openings <NUM> are provided, each being configured to receive a corresponding rod <NUM> in a relatively tight clearance fit.

With the filter <NUM> in position in the filter enclosure <NUM>, both the rods <NUM> and the elongate openings <NUM> extend in the insertion direction I. As such, during relative movement between the closure plate <NUM> and the filter body <NUM>, the rods <NUM> and, by association, the closure plate <NUM>, are able to move only in the insertion and removal directions. This guards against any relative translational movement, or 'sliding', between the closure plate <NUM> and filter body <NUM> in a direction perpendicular to the insertion direction I.

Referring again to <FIG>, the filter <NUM> and filter enclosure <NUM> comprise cooperating features to allow the filter <NUM> to be inserted into the filter enclosure <NUM> with ease.

In particular, the filter <NUM> and filter enclosure <NUM> together define a keyway arrangement such that the filter <NUM> may only be received into the filter enclosure <NUM> in a single orientation. In the depicted embodiment, the keyway arrangement comprises two opposing elongate ribs <NUM> mounted to the filter body, and two complimentary elongate recesses, or channels <NUM> extending into the main body <NUM> of the vacuum cleaner <NUM> from the filter enclosure <NUM>. Each rib <NUM> and channel <NUM> extends in a direction parallel with the insertion direction I. Each channel <NUM> extends downwardly from a first end 54a of the channel corresponding to the filter enclosure <NUM>, while an elongate rib <NUM> is mounted to, or forms part of, each of the front and rear sides <NUM>, <NUM> of the filter body <NUM>. While the described arrangement comprises two elongate ribs <NUM> and two channels <NUM>, it will be appreciated that any suitable number of ribs <NUM> and channels <NUM> may be used.

The enclosure opening has a central longitudinal axis A that is substantially perpendicular to the insertion direction I, extending from a front end to a rear end of the filter enclosure <NUM>. When the filter <NUM> is in position in the filter enclosure <NUM> the keyway arrangement of ribs <NUM> and channels <NUM> is offset from this central longitudinal axis A at the enclosure opening <NUM>. This can be seen in <FIG> and <FIG>, for example, which show that the ribs <NUM> are offset towards the left-hand side <NUM> of the filter body <NUM>. As such, there is only one position and orientation in which the filter <NUM> can be received by the filter enclosure <NUM>, ensuring that the user can only insert the filter <NUM> into the enclosure <NUM> in the correct orientation for operation.

The keyway arrangement may alternatively, or additionally, take the form of one or more hooks mounted to and extending from the filter body <NUM>, and receiving channels extending from the filter enclosure <NUM> into the main body <NUM> of the vacuum cleaner <NUM>. The hooks may be positioned on the front side <NUM> of the filter body <NUM>, and may extend in a direction that is transverse to the insertion direction I when the filter body <NUM> is in position in the filter enclosure <NUM>, into the receiving channels. In this way, in this example, the filter may only be inserted into the filter enclosure <NUM> by aligning the hooks with the receiving channels and simultaneously inserting the hooks into the channels while the filter <NUM> is lowered into the filter enclosure <NUM>.

In order to further increase the ease with which the filter <NUM> can be inserted into the enclosure <NUM>, each channel <NUM> is tapered slightly from the first end 54a. A width of each channel <NUM>, in a direction substantially perpendicular to the insertion direction I, is at a maximum at the first end 54a of the channel <NUM>, and decreases until the tapered portion meets a narrower portion of constant width, where the width of the channel <NUM> substantially corresponds to the width of the corresponding rib <NUM>. In this way, the user does not have to perfectly align the two ribs <NUM> of the filter body <NUM> with the corresponding channels <NUM> to insert the filter <NUM> into the filter body <NUM>. Instead, provided that the user places each rib <NUM> at some position in the wider first end 54a of the corresponding channel <NUM>, the rib <NUM> will then self-locate into the narrower portion as the filter <NUM> is inserted into the enclosure <NUM>.

The filter enclosure <NUM> additionally comprises a flexible side wall <NUM>, which can be seen in <FIG>. The flexible side wall <NUM> of the enclosure <NUM> is biased towards the filter body <NUM> when the filter <NUM> is in position in the filter enclosure <NUM>, and engages with the vertical left-hand side <NUM> of the filter body <NUM>. As such, the filter <NUM> is supported in position in the filter enclosure <NUM>, mitigating against relative movement between the filter <NUM> and enclosure <NUM> in a direction transverse to the insertion direction I. In addition, a seal is created between the flexible side wall <NUM> and the filter body <NUM>, guarding against the unintentional release of gases from within the filter body <NUM> into the enclosure <NUM>, and into the atmosphere. At the rear end of the filter enclosure <NUM>, an enclosure inlet opening <NUM> is provided corresponding to the filter inlet opening <NUM> of the filter body <NUM> and arranged to be aligned with the filter inlet opening <NUM> when the filter <NUM> is in position in the enclosure <NUM>.

The specific arrangement of the pre- and post-motor filters 18a, 18b will now be described. As can be seen in <FIG>, <FIG> and <FIG>, the pre-motor filter 18a and post-motor filter 18b are coupled together to form a single unit, or filter unit 18c, housed within the filter body <NUM>.

The pre- and post-motor filter 18a, 18b are each substantially annular in shape, and are concentrically arranged about a common axis C, such that the pre-motor filter 18a overlaps the post-motor filter 18b in a direction parallel with the common axis C. When the filter <NUM> is in position in the filter enclosure <NUM>, the common axis C is substantially horizontal, and is substantially perpendicular to the insertion direction I. The pre-motor filter 18a is positioned radially outward of the post-motor filter 18b, in a direction perpendicular to the common axis C, such that the pre-motor filter 18a effectively surrounds the post-motor filter 18b.

The pre- and post-motor filters 18a, 18b therefore form a compact arrangement, and the overall size of the filter <NUM> can be minimised. This is advantageous from a packaging perspective, allowing the size and weight of the vacuum cleaner <NUM> to be reduced and/or freeing up space in the main body <NUM> of the vacuum cleaner <NUM> for other components.

The pre-motor filter 18a can be formed of any suitable filter material, or a combination of filter materials typically found in pre-motor filters. In the described arrangement, the pre-motor filter 18a comprises layers of filter media, including a layer of scrim or web material, a non-woven filter medium such as fleece, followed by a further layer of scrim or web material. An electrostatic filter medium could also be included if desired. The post-motor filter 18b can similarly be formed of any suitable filter material, or combination of materials, typically found in post-motor filters. In the present embodiment, the post-motor filter 18b is formed of a pleated HEPA-standard filter medium.

The pre-motor filter 18a is mounted to a first support frame <NUM> of the filter unit 18c, while the post-motor filter 18b is mounted to a second support frame <NUM> of the filter unit 18c, arranged to be received by, and mounted to, the first. As will be described in more detail below, the pre-motor filter 18a, post-motor filter 18b and first and second support frames <NUM>, <NUM> are connected in such a way as to define a number of distinct channels, or pathways, for guiding air flowing through the filter unit 18c.

The filter unit 18c has a first end <NUM> corresponding to the left-hand side <NUM> of the filter body <NUM>, when the filter unit 18c is in position in the filter body <NUM>, and a second end <NUM> opposing the first, corresponding to the right-hand side <NUM> of the filter body <NUM>. The second end <NUM> follows the shape of the right-hand side <NUM> of the filter body <NUM>, and is therefore at a transverse angle to the insertion direction I. Similarly, the first end <NUM> is substantially vertical, parallel to the insertion direction I, in line with the left-hand side <NUM> of the filter body <NUM>.

The second support frame <NUM> is positioned intermediate the pre- and post-motor filters 18a, 18b and is annular in shape, comprising a series of spaced-apart longitudinal ridges <NUM> (shown in <FIG>) extending from the first end <NUM> of the filter unit 18c towards the second end <NUM>. As the second support frame <NUM> extends towards the second end <NUM> it tapers towards the common axis C, such that the ridges <NUM> define separate sloping channels between the pre-motor filter 18a and the second support frame <NUM> for the passage of air. These channels terminate at the second end <NUM> of the filter unit 18c in a pre-motor outlet <NUM>.

Radially inward of these sloping channels, the second support frame <NUM> and post-motor filter 18b define a substantially annular channel therebetween, which terminates in a filter outlet <NUM> at the first end <NUM> of the filter unit 18c. Radially inward still, the second support frame <NUM> and post-motor filter 18b together define a cylindrical channel extending through a central core of the filter unit 18c, which terminates in a post-motor inlet <NUM> at the second end <NUM>. As can be seen in <FIG> and <FIG>, a seal <NUM> is provided at the second end <NUM> of the unit 18c to mitigate against any passage of air therethrough other than through the pre-motor outlet <NUM> or post-motor inlet <NUM>.

At the first end <NUM> of the filter unit 18c, the second support frame <NUM> comprises an outer wall <NUM> having gripping means <NUM>, to allow a user to remove the filter unit 18c from the filter body <NUM> and to handle the filter unit 18c with ease. In the depicted arrangement, the gripping means <NUM> takes the form of two recesses that are a mirror image of one another about an intermediate dividing wall <NUM>. In particular, they are substantially hemispherical in cross-section taken parallel to the plane of the outer wall <NUM>. The dividing wall <NUM> essentially forms a grip feature, which the user can pinch between a finger and thumb when they wish to extract the filter unit 18c from the filter body <NUM>.

During operation of the vacuum cleaner <NUM>, dirt-laden air is drawn into the cyclonrry, ic separating unit <NUM> and dirt and debris are separated from the air. The air is subsequently expelled from the cyclonic separating unit <NUM> and flows through the enclosure inlet opening <NUM> and the adjoining filter inlet opening <NUM> to enter the filter unit 18c. The air is then drawn generally radially inwardly through the pre-motor filter 18a, which separates smaller dirt and dust particles from the air. The cleaner air flows along the channels between the pre-motor filter 18a and the second support frame <NUM> before passing out of the pre-motor outlet <NUM>. After passing through the motor <NUM>, the air is forced back into the filter unit 18c through the post-motor inlet <NUM> into the annular channel between the second support frame <NUM> and post-motor filter 18b. The air travels radially outwardly, though the post-motor filter 18b and is expelled from the filter unit 18c through the filter outlet <NUM>, before being exhausted from the vacuum cleaner <NUM>.

Positioning of the pre-motor filter 18a radially outward of the post-motor filter 18b advantageously ensures that the filter required to carry out the more significant cleaning operation also has the largest surface area.

The retention means <NUM> of the filter arrangement <NUM> will now be described in more detail, with reference to <FIG> and <FIG>. The retention means <NUM> comprises a first latching mechanism <NUM> associated with the closure plate <NUM>, and a second latching mechanism <NUM> associated with the filter body <NUM>.

The first latching mechanism <NUM> is a two-state latching mechanism in the form of a conventional push-push latch, and comprises a receiving portion <NUM> and an activation pin <NUM> as can be seen in <FIG> in particular. The filter enclosure <NUM> defines a shelf <NUM> at the front end, slightly offset from the enclosure opening <NUM> in the insertion direction I, and the receiving portion <NUM> of the first latching mechanism <NUM> is mounted in a substantially central position on this shelf <NUM>. The activation pin <NUM>, configured to operate the receiving portion <NUM>, is mounted to, or is integral with, an underside of the closure plate <NUM> at the front end of the plate <NUM> and extends generally vertically in the insertion direction I. The receiving portion <NUM> and activation pin <NUM> are so-positioned that they are aligned when the filter <NUM> is inserted into the filter enclosure <NUM>.

The receiving portion <NUM> comprises two receiving arms <NUM>, each mounted either side of an activation button <NUM>. Each arm <NUM> is pivotable relative to the activation button <NUM>, such that upper ends of the arms <NUM> can be brought closer together or further apart depending on the state of the first latching mechanism <NUM>. Each arm <NUM> comprises a protrusion at its upper end, such that it effectively forms a hook, capable of latching on to a complimentary protrusion formed at a lower end of the activation pin <NUM>.

Operation, or activation, of the activation button <NUM> by the activation pin <NUM> causes the first latching mechanism <NUM> to change state, and for the receiving arms <NUM> to move position. In particular, if the arms <NUM> begin in a position in which they are spaced apart, operation of the activation button <NUM> by the pin <NUM> causes the arms <NUM> to move closer together, so that the arms <NUM> effectively embrace the activation pin <NUM>. Subsequent operation of the button <NUM> causes the arms <NUM> to separate again, and so on.

With the closure plate <NUM> in the first position, the first latching mechanism <NUM> is in a latched state. In this state, the receiving arms <NUM> embrace the activation pin <NUM>, and the protrusion of each arm <NUM> is hooked onto the complimentary protrusion of the pin <NUM>. With the closure plate <NUM> in the second position, the first latching mechanism <NUM> is in an unlatched state, and the receiving arms <NUM> are splayed apart at their upper ends, such that the activation pin <NUM> is released. The first latching mechanism <NUM> is activated by movement of the closure plate <NUM> relative to the filter body <NUM> between the first position and the depressed position, and between the second position and the depressed position.

Movement of the closure plate <NUM> relative to the filter body <NUM> additionally operates the second latching mechanism <NUM>. This second latching mechanism <NUM> is at least partly visible in <FIG>, <FIG>, <FIG> and <FIG>, and comprises a latch element <NUM>, a latch member in the form of a latch bolt <NUM> and a complimentary recess <NUM> of the filter enclosure <NUM>.

The latch element <NUM> is mounted to, or is integral with, the closure plate <NUM>, and extends generally vertically in the insertion direction I from the underside of the closure plate <NUM>, as can be seen in <FIG>. The latch bolt <NUM> is itself carried in a track on the filter body <NUM>, and is slidable relative to the filter body <NUM> during operation of the second latching mechanism <NUM>. A lower end of the latch element <NUM>, remote from the closure plate <NUM>, is configured to engage a first end 102a of the latch bolt <NUM>. In the depicted arrangement, the latch bolt <NUM> is substantially perpendicular to the latch element <NUM>, such that the latch element <NUM> meets the latch bolt <NUM> at a right angle.

The latch element <NUM> is wedge-shaped at the lower end, and is provided with an angled lower surface. In other words, towards the lower end, the latch element <NUM> appears to taper and become narrower in a direction perpendicular to the insertion direction I. The first end 102a of the latch bolt <NUM> is provided with a corresponding angled surface, which is at broadly the same angle as, and is in sliding engagement with, the angled lower surface of the latch element <NUM>. A second end 102b of the latch bolt <NUM>, opposite to the first end 102a, is arranged to be received into the complimentary recess <NUM> of the filter enclosure <NUM>, to engage with the enclosure <NUM> during movement of the latch bolt <NUM>.

In use, when the closure plate <NUM> is moved relative to the filter body <NUM>, the angled lower surface of the latch element <NUM> engages the corresponding angled surface of the latch bolt <NUM>, staying in contact with the latch bolt <NUM> while moving relative thereto. When the closure plate <NUM> is moved in the insertion direction I, the angled lower surface of the latch element <NUM> progressively forces the latch bolt <NUM> outwardly, as the portion of the latch element <NUM> in contact with the bolt <NUM> increases in thickness. This drives the bolt <NUM> in a latching direction L perpendicular to the insertion direction I and into the corresponding recess <NUM> of the enclosure <NUM>.

In reverse, when the closure plate <NUM> moves in the removal direction, the latch bolt <NUM> travels along the angled lower surface of the latch element <NUM> and, as the latch element <NUM> tapers and reduces in thickness, moves inwardly, in a withdrawal direction opposite to the latching direction L, retracting out of the recess <NUM> of the enclosure <NUM>. To aid this inwards movement of the latch bolt <NUM>, the bolt <NUM> is connected to a latch mount <NUM> provided on the filter body <NUM>, and is biased relative to the latch mount <NUM>. Specifically, a tension spring <NUM> is connected to the latch mount <NUM> at one end and the latch bolt <NUM> at the other, to bias the latch bolt <NUM> out of the recess <NUM> and out of engagement with the filter enclosure <NUM>. When the closure plate <NUM> moves in the insertion direction I, the latch element <NUM> forces the latch bolt <NUM> to move against the force of the tension spring <NUM>.

When the closure plate <NUM> is in the first position, the latch bolt <NUM> extends partway into the recess <NUM> of the filter enclosure <NUM>, such that any movement of the filter body <NUM> relative to the filter enclosure <NUM> in the removal direction would cause the latch bolt <NUM> to contact the filter enclosure <NUM>. In the depressed position, the latch bolt <NUM> extends fully into the recess <NUM> of the filter enclosure <NUM>, such that any relative movement in the removal direction similarly causes contact between the latch bolt <NUM> and enclosure <NUM>. The second latching mechanism <NUM> is therefore in a latched state in both the first position and the depressed position. However, when the closure plate <NUM> is in the second position, and is elevated above the enclosure opening <NUM>, the second latching mechanism <NUM> is in an unlatched state, and the latch bolt <NUM> is fully withdrawn from the recess <NUM> of the enclosure <NUM>, permitting removal of the filter body <NUM> from the filter enclosure <NUM> in the removal direction.

While the retention means <NUM> has been described as comprising both the first <NUM> and the second <NUM> latching mechanisms, other arrangements are envisaged in which the second latching mechanism <NUM> is omitted, and only the first latching mechanism <NUM> is used to releasably retain the filter <NUM> in the filter enclosure <NUM>.

The following passages describe the typical sequence of steps carried out by a user, when maintenance of the filter unit 18c is necessary. Reference is made to <FIG>.

As has been mentioned previously, during normal operation of the vacuum cleaner <NUM> the filter <NUM> is positioned inside the filter enclosure <NUM>, and the closure plate <NUM> is in the first position, in which it sits substantially flush with the upper surface of the main body <NUM> of the vacuum cleaner <NUM>. In this position, the first <NUM> and second <NUM> latching mechanisms are each in their respective latched states.

In terms of the first latching mechanism <NUM>, with the closure plate <NUM> in the first position, the receiving arms <NUM> of the receiving portion <NUM> embrace the activation pin <NUM>, hooking the protrusion of the activation pin <NUM> and guarding against movement of the closure plate <NUM> out of the filter enclosure <NUM> in the removal direction. In terms of the second latching mechanism <NUM>, the second end 102b of the latch bolt <NUM> protrudes partway into the complimentary recess <NUM> of the filter enclosure <NUM> under the action of the latch element <NUM>, guarding against movement of the filter body <NUM> out of the filter enclosure <NUM> in the removal direction.

When it is desired for the filter <NUM> to be removed from the filter enclosure <NUM>, the user can push down at any position on the closure plate <NUM>, until the closure plate <NUM> is in the depressed position. In this depressed position, the closure plate <NUM> is at the limit of travel in the insertion direction I relative to the filter body <NUM>, and is depressed below the upper surface 12a of the main body <NUM>, as is shown in <FIG>. As the closure plate <NUM> takes the depressed position, the activation pin <NUM> contacts and depresses, or operates, the activation button <NUM>.

Upon operation of the activation button <NUM>, the button <NUM> may 'click', providing the user with haptic, or tactile, feedback that the button <NUM> has been successfully operated. The user then releases pressure on the closure plate <NUM>, which is biased in the removal direction, towards the second position. The closure plate <NUM> moves away from the filter body <NUM> under the action of the compression spring <NUM>, the activation button <NUM> is released and the receiving arms <NUM> separate, thereby releasing the activation pin <NUM> and unlatching the first latching mechanism <NUM>. The closure plate <NUM> is urged by the compression spring <NUM> into the second position.

The second latching mechanism <NUM> is unlatched simultaneously. As the closure plate <NUM> takes the depressed position, the latch bolt <NUM> is forced by the latch element <NUM> further into the complimentary recess <NUM> of the filter enclosure <NUM>, as shown in <FIG>. As the user subsequently releases pressure on the closure plate <NUM>, the latch element <NUM> moves in the withdrawal direction, away from the filter body <NUM>, and the latch bolt <NUM> is urged by the tension spring <NUM> out of the complimentary recess <NUM> of the filer enclosure <NUM>.

When the closure plate <NUM> is in the second position, shown in <FIG> and <FIG>, the entire plate <NUM> is elevated above, and spaced slightly apart from, the upper surface 12a of the main body <NUM> of the vacuum cleaner <NUM>. This permits a user to grasp the sides and/or underside of the closure plate <NUM> for removing the filter <NUM> from the filter enclosure <NUM>. In this second position, the receiving arms <NUM> of the first latching mechanism <NUM> are still spaced apart in the unlatched position, while the latch bolt <NUM> is fully withdrawn from the complimentary recess <NUM> of the filter enclosure <NUM>. As such, the first <NUM> and second <NUM> latching mechanisms are each in their respective unlatched states.

From this position, the user can remove the filter <NUM> from the filter enclosure <NUM> in the removal direction, as shown in <FIG>, before grasping the dividing wall <NUM> of the filter unit gripping means <NUM>, and extracting the filter unit 18c from the filter body <NUM> in the manner shown in <FIG>. The user is then free to wash the pre- and post-motor filters 18a, 18b, or to replace the filters, if required.

Once any maintenance activities on the filter unit 18c are completed, the filter <NUM> can be reinserted into the filter enclosure <NUM> by broadly reversing the sequence of steps taken to remove the filter <NUM>.

In brief, the user aligns the elongate ribs <NUM> of the filter body <NUM> with the complimentary channels <NUM> that extend from the enclosure opening <NUM>, and inserts the filter <NUM> into the filter enclosure <NUM> in the insertion direction I. Without any pressure applied to the closure plate <NUM>, once the filter body <NUM> reaches a base of the filter enclosure <NUM>, the closure plate <NUM> sits in the second position, raised slightly above the upper surface 12a of the vacuum cleaner main body <NUM>. In this position, the first <NUM> and second <NUM> latching mechanisms are in their respective unlatched states.

The user then applies pressure to the closure plate <NUM> in the insertion direction, pushing the closure plate <NUM> down towards the depressed position, such that the activation pin <NUM> of the closure plate <NUM> contacts the activation button <NUM> of the receiving portion <NUM>. Upon depression of the button <NUM>, the user again experiences feedback, indicating that the button <NUM> has been successfully operated, and the receiving arms <NUM> move towards one another. In this depressed positon, the protrusion of the activation pin <NUM> still sits beneath the protrusions of the receiving arms <NUM>, so that the pin <NUM> can still move a short way relative to the arms <NUM> in the removal direction.

Under the action of the compression spring, the closure plate <NUM> moves slightly away from the filter body <NUM>, into the first position, in which the protrusion of the activation pin <NUM> is in contact with the protrusion of the receiving arms <NUM>, and the activation pin <NUM> is hooked by the receiving arms <NUM>.

The second latching mechanism <NUM> is again operated simultaneously with the first. When the closure plate <NUM> is pushed down towards the depressed position, the latch element <NUM> of the second latching mechanism <NUM> travels in the insertion direction I, forcing the latch bolt <NUM> to move in a perpendicular direction, against the action of the tension spring <NUM>, into engagement with the complimentary recess <NUM> of the enclosure <NUM>. With the closure plate <NUM> in the depressed position, the latch bolt <NUM> is at the limit of its travel into the complimentary recess <NUM>.

When the closure plate <NUM> subsequently moves into the first position, the latch bolt <NUM> retracts slightly, but remains in the complimentary recess <NUM> of the filter enclosure. With the closure plate <NUM> back in the first position, each of the first <NUM> and second <NUM> latching mechanisms are therefore in their respective latched states, and neither the closure plate <NUM> nor the filter body <NUM> is able to move relative to the filter enclosure <NUM> in the removal direction.

Many modifications may be made to the above examples without departing from the scope of the present invention as defined in the appended claims.

For example, while the receiving portion of the first latching mechanism <NUM>" has been described as being mounted on a shelf of the filter enclosure, the receiving portion may alternatively be positioned on an upper surface of the filter body <NUM>", as shown in <FIG>. In this case, when the closure plate <NUM>" is in the first position and is moved in the insertion direction I", the activation pin mounted to the closure plate <NUM>" operates the receiving portion mounted to the filter body <NUM>" in the same manner as previously described. In this way, the first latching mechanism <NUM>" is configured to latch and unlatch the closure plate <NUM>" to and from the filter body <NUM>".

The closure plate may alternatively or additionally be pivotably mounted to the filter body <NUM>‴, at the front end of the closure plate <NUM>‴, for example. In this example, with the closure plate <NUM>‴ in the first position, the closure plate <NUM>‴ still sits substantially flush with the upper surface 12a‴ of the main body <NUM>‴, while in the second position only a rear end of the closure plate <NUM>‴ is elevated above the enclosure opening <NUM>‴, as depicted in <FIG>. Other features of the arrangement may substantially correspond to those features described previously, with the latch element of the second latching mechanism <NUM>‴ extending from the underside of the closure plate <NUM>‴ at the rear end thereof.

In another arrangement (not shown), the closure plate <NUM> may not be connected to the filter body <NUM>, and may therefore be removed from the filter enclosure <NUM> independently of the filter body <NUM>. In this arrangement, the first <NUM> and/or second <NUM> latching mechanism may operate substantially as has been described herein, such that when the closure plate <NUM> is moved from the first position or the second position into the depressed position, the retention means <NUM> is operated. In this example, the closure plate <NUM> may be biased into the second position relative to the filter enclosure <NUM> or to the main body <NUM> of the vacuum cleaner <NUM>. Once in the second position, the closure plate <NUM> can be removed from the filter enclosure <NUM>, allowing subsequent access to, and removal of, the filter body <NUM>.

As has been mentioned previously, arrangements are also envisaged in which the actuation portion <NUM>iv forms part of the filter body <NUM>iv, and in which the first <NUM>iv and second latching mechanisms may be associated with the filter body <NUM>iv. In addition, or as an alternative, the receiving portion <NUM>iv of the first latching mechanism <NUM>iv may be mounted to the base of the filter enclosure <NUM>iv, while the activation pin <NUM>iv extends from a base of the filter body <NUM>iv, as is shown in <FIG>.

While arrangements have been described in which the first latching mechanism <NUM> is a single two-state latching mechanism, it is envisaged that any suitable number of two-state latching mechanisms may be used. For example, it is envisaged that the first latching mechanism <NUM> may comprise two two-state latching mechanisms, with one at each of the front and rear end of the closure plate <NUM>. In this arrangement, both two-state latching mechanisms can be operated simultaneously by moving the closure plate <NUM> in the insertion direction I.

Turning now to <FIG>, the latch bolt of the second latching mechanism has been described herein as being slidable relative to the filter body. However, it is envisaged that the latch bolt <NUM>v may instead form part of the filter body (not shown), such that the filter body is itself forced into engagement with the filter enclosure <NUM>v when the closure plate <NUM>v is moved in the insertion direction I. For example, there may in fact be two latch bolts <NUM>v fixedly mounted to, or forming part of, the filter body, extending generally in the insertion direction I on the front side of the filter body and being received in complimentary recesses <NUM>v of the filter enclosure <NUM>v. In this example, the closure plate <NUM>v similarly comprises two wedge-shaped latch elements <NUM>v extending from the underside of the closure plate <NUM>v.

Claim 1:
A filter arrangement (<NUM>) for a vacuum cleaning appliance (<NUM>), comprising:
a filter enclosure (<NUM>) having an enclosure opening;
a filter (<NUM>) configured to be received through the enclosure opening into the filter enclosure in an insertion direction; and
retention means (<NUM>) operable between latched and unlatched states for releasably retaining the filter (<NUM>) in the filter enclosure, characterised in that
the filter (<NUM>) includes an actuation portion (<NUM>) configured to operate the retention means (<NUM>), wherein the actuation portion (<NUM>) is moveable between at least first and second positions and is biased towards the second position,
wherein, when the filter (<NUM>) is in the filter enclosure, movement of the actuation portion in the insertion direction from the first position to a depressed position transitions the retention means to the unlatched state, whereinafter the actuation portion is moved to the second position in which at least a part of the actuation portion (<NUM>) is elevated above the enclosure opening, and wherein the filter (<NUM>) further includes a filter body (<NUM>), and wherein the actuation portion (<NUM>) is movable relative to the filter body (<NUM>).