REFERENCE TO RELATED APPLICATIONS

This application claims priority of United Kingdom Application No. 1721394.3, filed Dec. 20, 2017, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a filter assembly.

BACKGROUND OF THE INVENTION

Filters are key components in products containing motors, and particularly motors which generate a flow of fluid through the product such as vacuum cleaners. Without filters, dirt and debris can enter the motor, reducing its efficiency and performance overtime. In addition, motors themselves can produce emissions in the form of particles which may be undesirable to be released into the atmosphere.

However, the addition of filters to a product can impact the size of the product, particularly if more than one filter is required in order to filter both upstream and downstream of a motor. In addition, filters typically require maintenance by a user, whether that be replacement or removal for cleaning, and multiple filters to maintain can lead to frustration for a user.

Therefore there is a need for improvements to be made to filters that can go some way to alleviate these problems.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides a filter assembly comprising: a filter housing; a first filter; and a second filter, wherein the first filter is a pre-motor filter, and the second filter is a post-motor filter, and both the first and second filters are fixed to the filter housing and are annular about a common axis.

By combining both the pre-motor and post-motor filters into a single assembly, a more compact and convenient motor filter assembly can be achieved. Furthermore, a user is able to handle and interact with both filters simultaneously. For example, removing, replacing, washing or cleaning both the filters can be done in a single action instead of the user having to do so for each filter individually. In addition, the annular shape of the filters provides a particularly efficient use of space, whereby a motor can be positioned at least partially within the annular shape defined by the filters.

The cross-sectional shape of one or both of the first and second filters may be one of circular, elliptical or obround. Motors tend to have a generally cylindrical shape, and providing the filters with a cross sectional shape that substantially matches that of the outside of the motor or motor housing, a particularly space-efficient filter can be achieved.

The first filter may be adjacent the second filter in a direction along the common axis. As a result, the filter surface area can be maximised while keeping the overall size of the filter assembly to a minimum.

The filter housing may comprise an exposed portion and an enclosed portion. The exposed portion of the filter housing may comprise a frame extending from the enclosed portion, the first filter being positioned around the frame. The enclosed portion of the filter housing may comprise an outer casing, and the second filter may be positioned inside the outer casing.

As a result the exposed portion allows for efficient fluid flow to and around the pre-motor filter, which can allow even-loading of the flow around the filter. The enclosed portion allows a part of the filter assembly to remain enclosed such that a user can hygienically handle the filter assembly by the enclosed portion without getting filtered dirt or dust on their hands.

The outer casing may have vent holes. As a result, fluid flowing through the post-motor filter is able to exit the enclosed portion of the filter housing.

The first filter may comprise a layered filter medium, and the second filter may be a pleated filter.

The filter housing may comprise an annular seal between the first and second filters. As a result, the seal can ensure that there is no fluid leakage around the housing between the pre- and post-motor filters. Any such fluid leakage around the housing could reduce the performance of a motor positioned within the filter assembly.

The flow direction for the first filter may be opposite to the flow direction for the second filter. As a result, there is an efficient fluid flow through the filter assembly which minimises any changes of direction for the fluid flow, which can have a negative impact on efficiency and performance of a machine.

The flow direction for the first filter may be radially inwards towards the common axis, and the flow direction for the second filter may be radially outwards away from the common axis. As a result, the filter assembly can conveniently be positioned around a motor positioned along the common axis, maximising the use of space, while providing efficient filtration of fluid flowing into and out of the motor.

A second aspect of the present invention provides a product comprising a motor, and the filter assembly described in any one of the previous statements, wherein the filter assembly at least partially overlaps with the motor in a direction along the common axis.

As a result the filter assembly surrounds the motor in a particularly space efficient arrangement. This helps to minimise the overall size of the product.

The filter assembly may be positioned around the motor such that the first filter is positioned around an inlet to the motor, and the second filter is positioned around an outlet of the motor. As a result, fluid passes through the pre-motor filter directly into the inlet to the motor, and air leaving the motor passes directly through the post-motor filter.

The motor may be housed in a cylindrical motor bucket having a motor bucket inlet and a motor bucket outlet, the filter assembly being positioned around the motor bucket and being removable from the product by sliding the filter assembly over the motor bucket along the direction of the common axis. As a result, the filter assembly can be quickly and easily removed from the motor bucket, and maintenance of the filters is more convenient for a user.

The motor bucket inlet may comprise a plurality of through-holes aligned with the inlet of the motor, and the motor bucket outlet may comprise a plurality of through-holes aligned with the outlet of the motor. As a result, the through holes allow fluid to flow easily through the motor bucket, without unnecessarily compromising the structural integrity of the motor bucket.

The filter housing may comprise an annular seal between the first and second filters, the annular seal being in sealing contact with a solid central portion of the motor bucket between the motor bucket inlet and motor bucket outlet. As a result, the seal can ensure that there is no fluid leakage around the housing between the motor bucket inlet and motor bucket outlet. Any such fluid leakage around the housing could reduce the performance of the motor, and as a result the performance of the product.

The product may be a vacuum cleaner.

At least part of the filter assembly may form at least part of an outer surface of the product. As a result, the filter assembly can be easily accessed by a user, and filter maintenance is made easier.

The filter housing may comprise an enclosed portion comprising an outer casing, and it may be the outer casing that forms at least part of an outer surface of the product.

