FIELD OF THE INVENTION The present invention relates to a vacuum cleaner, and in particular to a vacuum cleaner having a printed circuit board.

BACKGROUND OF THE INVENTION Printed circuit boards, commonly known as PCBs, are widely used for electronic control in vacuum cleaners. There is a desire for PCBs to be as small as possible, yet reducing the size of a PCB may have associated disadvantages, such as, for example, a temperature increase during operation of the PCB. SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a vacuum cleaner comprising a main body, a motor-driven fan unit, a printed circuit board for controlling the motor-driven fan unit, and a housing encasing a portion of the printed circuit board, wherein a heat sink of the printed circuit board extends through the housing from an interior of the housing to an exterior of the housing, and the printed circuit board is disposed within the main body such that the heat sink is located in an air-flow path through the main body. The vacuum cleaner according to the first aspect of the present invention may be advantageous principally as the vacuum cleaner comprises a printed circuit board for controlling the motor-driven fan unit, and a housing encasing a portion of the printed circuit board, wherein a heat sink of the printed circuit board extends through the housing from an interior of the housing to an exterior of the housing, and the printed circuit board is disposed within the main body such that the heat sink is located in an air- flow path through the main body. In particular, as a portion of the printed circuit board is encased by the housing, the portion of the circuit board encased by the housing may be of a lower pollution degree than, for example, a portion of the printed circuit board not encased by a housing, as the housing may protect the encased portion of the printed circuit board from ingress of dust and debris and the like, as well as moisture.

As the encased portion of the printed circuit board may be of a lower pollution degree than a non-encased portion of a printed circuit board, components mounted to the surface of the printed circuit board encased by the housing may be placed closer together than would typically be permissible for a higher pollution degree environment. This may enable a reduction in size of the printed circuit board, which may allow for more efficient packaging of the printed circuit board within the vacuum cleaner. However, as a portion of the printed circuit board is encased by the housing, the temperature inside the housing may rise to unacceptable levels in use, particularly where, for example, components mounted to a surface of the printed circuit board encased by the housing are placed closer together than would typically be the case. The provision of a heat sink extending from an interior of the housing to an exterior of the housing, and the printed circuit board being disposed within the main body such that the heat sink is located in an air-flow path through the main body, may enable excess heat to be removed from the interior of the housing, thereby ensuring acceptable temperature levels within the housing in use. Furthermore, as a portion of the printed circuit board is encased by the housing, it may be possible to place the printed circuit board in an untreated air flow path through the vacuum cleaner in use, for example an air flow path containing nominal amounts of dust or debris or the like, as the housing may protect the components mounted therein from any dust or debris within the airflow. This may, for example, enable the printed circuit board to be exposed to a flow of untreated ambient air from an exterior of a vacuum cleaner to an interior of the vacuum cleaner, which may be beneficial as the untreated ambient air may have a lower temperature than, for example, air which has been worked on by a dirt separator and/or motor of the vacuum cleaner, and hence may have an enhanced cooling effect. Printed circuit boards are commonly known as PCBs, and the term PCB will be widely recognised by a person skilled in the art.

Only a portion of the PCB may be encased by the housing, for example such that at least a portion of the PCB is not encased by the housing. This may be beneficial as the greater the area of the PCB that is encased by the housing, the larger the heat sink needed to regulate temperature within the housing. By only encasing a portion of the PCB with the housing, it may be possible to maintain a low size of heat sink whilst still providing appropriate protection for certain components of the PCB, for example for surface mounted components of the PCB.

The housing may extend from a surface of the PCB. A surface of the PCB and the housing may together define an enclosure, for example with the surface of the PCB being exposed to the interior of the enclosure. The housing may be mounted to a surface of the PCB, for example a surface of the PCB on which components are mounted. The housing may be mounted to a surface of the PCB at a region spaced from the perimeter of the PCB. This may be beneficial over, for example mounting the housing to the perimeter/edge of the PCB as this may remove the need for the housing to extend about the entirety of the perimeter/edge of the PCB and/or may provide for a simpler mounting of the housing, as this may remove the need to shape the housing to account for input terminals and the like.

The housing may comprise a seal located at an interface between the housing and the PCB, for example such that the portion of the PCB encased by the housing is hermetically sealed. This may be beneficial as sealing the interface between the housing and the PCB may enable the region of the PCB in the interior of the housing to be a different pollution degree to the region of the PCB external to the housing. The portion of the PCB encased by the housing may comprise surface mounted components of the PCB. This may be beneficial as the surface mounted components may require smaller, if any, lead connections, and hence the structure of the housing to accommodate such connections may be relatively simple. Furthermore, surface mounted components may be located closer together than non-surface mounted components, and may therefore enable the use of a smaller housing and/or a smaller PCB. The portion of the PCB encased by the housing may comprise a different pollution degree, for example a lower pollution degree, to a portion of the PCB not encased by the housing. This may provide for a reduced total size of the PCB relative to a PCB without a housing and/or having a single pollution degree. The portion of the PCB encased by the housing may comprise a region of pollution degree 2 or 1.

The vacuum cleaner may comprise a dirt separator, a first air inlet, a second air inlet, a first air flow path between the first air inlet and the dirt separator, and a second air flow path between the second air inlet and the motor-driven fan unit, and the PCB may be located in the second air flow path. This may be beneficial as air from the second air flow path may be cooler than air from the first air flow path, for example, air which has been worked on by the dirt separator in use, and so may provide enhanced cooling of the interior of the housing via interaction with the heat sink. The second air flow path may comprise an air flow path for untreated air. The second air inlet may be spaced apart from the first air inlet, and may, for example, be spaced apart from a surface to be cleaned in use. The second air inlet may be formed in the main body. The first air inlet may comprise a dirty air inlet, for example a dirty air inlet formed upstream of the dirt separator, and the dirty air inlet may be located in a region of a surface to be cleaned in use. The second air flow path may be at least partially generated by the motor-driven fan unit. The motor-driven fan unit may create a negative pressure within the main body which draws air from the exterior of the main body to the interior of the main body, for example via the second air inlet. The motor-driven fan unit may comprise at least one bleed, and, for example, the at least one bleed may be located pre- the motor of the motor driven fan unit.

According to a second aspect of the present invention there is provided a printed circuit board for controlling a motor-driven fan unit, the printed circuit board comprising a housing encasing a portion of the printed circuit board, and a heat sink extending through the housing from an interior of the housing to an exterior of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the present invention, and to show more clearly how the invention may be put into effect, the invention will now be described, by way of example, with reference to the following drawings:

Figure 1 is a perspective view of a disassembled vacuum cleaner according to a first aspect of the present invention;

Figure 2 is a top plan view of a main body of the vacuum cleaner of Figure 1;

Figure 3 is top plan view of the main body of Figure 2 with an uppermost surface of the main body removed.

Figure 4 is a rotated view of the main body of Figure 3;

Figure 5 is a perspective view of a printed circuit board (PCB) used in the vacuum cleaner of Figure 1;

Figure 6 is a first perspective view of the PCB of Figure 5 with its housing removed; and Figure 7 is a second perspective view of the PCB of Figure 5 with its housing removed.

DETAILED DESCRIPTION

A vacuum cleaner according to a first aspect of the present invention, generally designated 10, is shown in Figure 1. The vacuum cleaner 10 comprises a main body 12, a separating apparatus 14, a flexible hose 16, a wand assembly 18, and a cleaner head 20. The main body 12 is shown in isolation in Figures 2 to 4.

Mounted within the main body 12 are a motor-driven fan unit 114 for generating airflow through the separating apparatus 14 in use, a cable rewind unit (not shown) for retracting and storing an electrical cable within the main body 12, and appropriate control electronics 118 for controlling the cylinder vacuum cleaner 10.

The motor-driven fan unit 114 and cable rewind unit are conventional, and will not be described here in any detail.

The motor-driven fan unit 114 is housed in a motor bucket 115. The motor bucket 115 is connected to the main body 12 so that the motor-driven fan unit 114 does not rotate as the cylinder vacuum cleaner 10 is manoeuvred over a floor surface to be cleaned in use.

The motor bucket 115 has a plurality of bleeds 117, and the plurality of bleeds 117 are located pre- the motor of the motor-driven fan unit 114. In use, the plurality of bleeds 117 generate a negative pressure within the main body 12, which acts to draw ambient air from the exterior of the main body 12 to the interior of the main body 12, via vents 123 and/or a cable inlet 125. The control electronics 118 comprise a PCB 122 according to the second aspect of the present invention, which is shown in Figures 5 to 7.

The PCB 122 comprises a substrate 124, a plurality of components 126 mounted to the substrate 124, a housing 128, and a heat sink 130.

The housing 128 comprises a seal 132, and is mounted to the surface of the substrate 124 such that surface-mounted components 126 of the PCB 122 are sealed within the housing 128. The heat sink 130 extends from the interior of the housing 128 to the exterior of the housing 128, and comprises a heat conductive metal plate.

As the housing 128 seals with the surface of the substrate 124, the region of the PCB 122 within the housing 128 is protected from moisture and dust, for example conductive dust. Thus the region of the PCB 122 within the housing 128 can be a different pollution degree to the remainder of the PCB 122, and in the presently preferred embodiment the interior of the housing 128 is of pollution degree 2, whilst the remainder of the PCB 122 external of the housing 128 is of pollution degree 3.

As the interior of the housing 128 is of pollution degree 2, the surface-mounted components 126 within the housing 128 can be placed closer together than, for example, if they were located exterior of the housing 128 in a region of pollution degree 3. This may enable the overall size of the PCB 122 to be reduced.

However, as the surface-mounted components 126 are enclosed within the housing 128, and as the distance between the surface-mounted components 126 is reduced, the temperature within the housing 128 can reach excessive levels during use. The heat sink 130 extends outwardly from the housing 128, and acts to regulate the temperature within the housing 128 by transferring heat from the interior of the housing 128 to the exterior of the housing 128 in use. The heat sink 130 extends outwardly from the housing 128 of the PCB 122, and is positioned within the interior of the main body 12 such that at least a portion of airflow from the vents 123 and/or the cable inlet 125 toward the plurality of bleeds 117 in the motor bucket 115 passes over the heat sink 130 in use. An example airflow is shown by arrow A in Figure 4. The combination of the heat sink 130 and the cooling airflow acts to maintain the temperature within the housing 128 at acceptable levels during use.