GB2491891A

GB2491891A - Hand drying apparatus

Info

Publication number: GB2491891A
Application number: GB1110255.5A
Authority: GB
Inventors: Jon Todd
Original assignee: Personnel Hygiene Services Ltd
Current assignee: Personnel Hygiene Services Ltd
Priority date: 2011-06-17
Filing date: 2011-06-17
Publication date: 2012-12-19
Also published as: WO2012172376A2; WO2012172376A3; EP2720595A2; GB201110255D0

Abstract

A hand dryer 1 includes a fan 4 and a housing defining a fan chamber 16 arranged to receive blown air from the fan 4. The fan chamber 16 comprises an outlet 44 defining the air outlet of the dryer 1 through which air is blown directly to the outside atmosphere. The fan chamber 16 is configured such that it tapers towards the outlet 44 to accelerate air flow therethrough. Preferably, the outlet 44 comprises an elongate slot and the fan chamber 16 tapers to the elongate slot to optimise drying airflow for hand drying with the letterbox configuration providing an airflow which effectively spans a user's hands during drying.

Description

A HAND DRYING APPARATUS

This present invention relates to a drying apparatus, and in particular an apparatus for drying hands.

Hand dryers are widely used in public conveniences, and also in the many other establishments. They are generally hygienic and quite effective, though they may have a not insignificant power usage which may not be efficiently utilised.

Prior art dryers are disclosed in for example US2007/0130789, GB2428569, GB2078510, AU 2005203363, and EP1250878. EP1250878 for example describes a hand dryer having a body containing a fan in which air from the fan is directed to an outlet grill via an outlet duct.

Due to environmental and regulatory pressures, there is an increasing need for hand dryers to operate more efficiently. To limit power consumption, it is known to provide hand dryers which operate without heating elements, which consume large amounts of power. In order to maintain drying efficiency in the absence of a heating element, such dryers are operated to generate higher airflow rates. However, increased airflow rates require higher fan speeds and resultant increased power consumption. While this may be less than the power consumption of a heated unit, the levels achieved nonetheless remain undesirably high.

There is also a need to simplify hand dryer construction to minimise parts, thereby simplifying assembly and reducing cost and material consumption.

It is therefore desirable to provide an improved hand dryer which addresses the above described problems andlor which offers improvements generally.

According to the present invention there is provided a drying apparatus as defined by the accompanying claims In an embodiment of the invention there is provided a hand drying apparatus. The apparatus includes a fan, and a housing defining a fan chamber arranged to receive blown air from the fan. The fan chamber comprises an outlet defining the air outlet of the drying apparatus through which air is blown directly to the outside atmosphere, and is configured such that the fan chamber tapers towards the outlet to accelerate air flow therethrough.

Conventional hand dryers of the prior art are known to include nozzles connected to or arranged downstream of the fan chamber in some way, to concentrate and accelerate the airflow from the fan. The outlet of such dryer arrangements is formed in a planar base or side wall portion of the housing. The applicant has found that by instead providing a fan chamber which tapers directly to the outlet, the airflow can be channelled and concentrated more effectively, thereby providing more efficient acceleration of the airflow and avoiding losses to turbulence generated in common fan chamber configurations of the prior art. Tn addition, providing a tapered fan chamber obviated the requirement for addition components such as nozzles or grates, thereby reducing part numbers, simplifying construction and hence reducing unit cost.

The outlet preferably comprises an elongate slot. Tapering the fan chamber to an elongate slot has been found by the applicant to provide the most effective drying airflow for hand drying as the letterbox configuration provides an airflow which effectively spans a user's hands during drying.

The outlet preferably has a length of between 60mm and 80mm, the length being the dimension extending laterally across the dryer when viewed from the front. This length provides a sufficiently contracted aperture size, while still enabling the airflow to span a pair of hands placed therein. Most preferably the length is 70mm.

The width of the outlet is between 10mm and 20mm, the width being the dimension of the outlet extending in the front-to-rear direction of the dryer. This width provides suitable airflow constriction while still providing an airflow cross-section suitable for use in drying hands. A more preferable outlet width is between 12mm and 17mm.

The chamber preferably comprises an upper portion which receives the outlet of the fan and a lower portion contiguous with the upper portion, wherein the outlet is arranged at the base of the lower portion with the lower portion tapering towards the outlet. The upper portion is suitably sized to receive the electric fan, with the constriction from the upper portion through the lower portion to the outlet providing the desired airflow acceleration.

The base of the housing may define and is equal in size to the outlet. Preferably the housing comprises a plurality of walls defining the chamber which terminate and have terminal edges which define the peripheral edges of the outlet. As such, the base of the housing comprises the lower terminal edges of the housing walls, and the outlet aperture defined therebetween. The base does not comprise an portion of the walls extending further past the outlet aperture more than the thickness of the walls. This arrangement provides the optimum airflow acceleration, as the air is funnelled directly to the outlet by the tapered walls.

At least two of the walls may converge towards each other to define a narrowing taper in the direction of the outlet. Preferably the housing comprises a front wall, two side walls, and a rear wall portion. The front wall extends in a substantially vertical direction, with the rear wall portion being angled forwardly towards the front wall. The front wall further includes a curved upper portion located adjacent the outlet of the fan.

The taper preferably extends to and terminates at the outlet, which no surplus portion of the housing extending past the outlet in any direction.

The air chamber preferably comprises a front wall section and a rear wall section and the front and rear walls are arranged to converge to define the narrowing taper in the direction of the outlet.

The front wall preferably comprises a lower portion which extends substantially vertically and the rear wall comprises a lower portion which slopes downwardly and forwardly towards the front wall to define the taper.

The taper extends to and terminates proximate the outlet. The walls of the air chamber may be arranged such that they are parallel immediately preceding the outlet, to ensure that the outlet air is directed in a parallel and common direction to maximise drying efficiency.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a side view of a hand drying apparatus according to the invention, with the front casing removed; Figure 2 is a perspective view from below of the apparatus of Figure 1; Figure 3 is a perspective section view from the side of the apparatus of Figure 1; and Figure 4 is a side on section view of the arrangement of figure 1.

Figure 1 shows a drying apparatus 1 suitable for use as a hand dryer. The hand dryer 1 includes a base plate 2 which is mountable to a wall or other fixture to support the hand dryer in a suitable location. An electric fan 4 is mounted to the upper part of the base plate 2. The fan 4 is a low vohage 400W electric wheel fan. The drive mechanism 5 of the fan 4 is partially received within a rear casing section 6, which is mounted to the base plate 2.

The rear casing section 6 may be integrally formed with the base plate 2. The rear casing section 6 extends forwardly from the base and comprises upper, lower and side walls. The front edges of the walls of the rear casing section define a front connection edge to which a front casing section 8 is secured to cover the drive mechanism 5 of the fan 4.

As shown in figure 2, the fan 4 includes a fan wheel 10 comprising a plurality of fan blades 12. The fan wheel 10 is connected to the drive shaft 14 of the drive mechanism 5, which defines the rotational drive axis of the fan wheel 10. The drive axis 14 of the fan drive mechanism S extends laterally across the dryer assembly 1, and the fan wheel 10 is positioned laterally to the side of the drive mechanism 5 in connection with the distal end of the drive shaft 14. The drive axis 14 is located at the centre of the fan wheel 10, and the blades 12 are arranged circumferentially around the periphery of the fan wheel 10.

An casing is provide about the fan 4 which defines an air chamber 16 configured to direct and channel air from the fan 4 to an outlet. The air chamber 16 comprises a front panel section 20 and a rear panel section 22, and laterally opposed side panels 18. The air chamber 16 has a two-part separable structure, with the front 20 and rear 22 panel sections comprising a separation line extending along their lengths. A plurality of connectors 24 connect opposing flange sections extending along either side of the separation line to join the two halves of the air chamber 16. A rubber gasket 26 is provided along the separation line to provide an air tight seal between the two halves of the air chamber 16.

The air chamber 16 comprises an upper section 28 and a lower section 30 which are integral and contiguous. The upper section 28 includes a wall portion 32 extending from the rear plate 2 and having a curved configuration which is substantially concentric with fan wheel 10. The wall section 32 is radially spaced from the fan wheel and curves forwardly at a substantially constant radial spacing until it is vertically oriented, at which point the wall section 32 continues vertically downwards.

The lower section 30 includes a front wall portion 34 and a rear wall portion 36. The front wall portion 34 continues from the upper wall portion 32 and extends vertically downwards therefrom. The front wall portion 34 terminates at a position spaced vertically downwards from the lowermost part of the fan wheel 10. The rear wall portion 36 is spaced rearwardly from the front wall portion 34. When used herein, the terms front and rear, and forwardly and rearwardly are used relative to the axis of the hand dryer 1 extending in a direction perpendicular to the plane defined by the base plate 2, and any planar surface to which it is secured. The rear portion 36 comprises a rearward section 38 which extends forwardly from the base plate 2 and curves radially inwardly towards the fan wheel 10, and a tapering section 40. The tapering section 40 is downwardly and forwardly away from the base plate 2, towards the front portion 34, such that the spacing between the front portion 34 and the tapering section of the rear portion 36 decreases towards the lower edge of the tapering portion 40.

The front portion 34 and the tapering portion 40 therefore define taper in the air chamber 6 forming a nozzle or funnel section 42 which is integral with the air chamber. At its lower end, the forward and downward slope of the tapered section 40 extends vertically downwards, such that the lowermost part of the tapered section 40 is substantially parallel to the front portion 34. The lower edges of the front portion 34 and tapering portion 40 are interconnected by the lower edges of the side panels 18, and together define an elongate slot 44 forming the outlet of the dryer 1. The size of the elongate outlet is selected such that its lateral dimension defining the length of the slot of between 60mm and 8 0mm, and preferably 70mm, which is substantially equivalent to the width of an average adult hand when cupped beneath a dryer. The width of the outlet is between 10mm and 20mm, and preferably 17mm.

In use, the fan wheel 10 is rotated forwardly which in the view shown in Figure 4 comprise rotation in a clockwise direction. Air drawn into the fan wheel 10 is expelled radially outwards by the fan blades 12 with a forwards momentum. The size of the fan wheel is selected to provide a large flow rate with a relatively low velocity. By minimising the fan velocity, the power of the may also be reduced, therefore improving the energy efficiency of the dryer 1. However, efficient drying performance requires a high velocity airflow at the outlet.

Air blown upwardly from the fan wheel 10 engages and is channelled downwardly by the curved inner surface of the upper section 28 of the air chamber 16. As the air moves downwardly it is passed into the lower section 30. The funnel defined by the reducing spacing between the tapering section 40 and the front portion 34 of the lower secretion 30 begins to constrict the downward air flow. As the cross sectional area A of the fluid channel defined by the lower section 30 decreases, while a constant flow rate Q is maintained by the fan 4, the airflow accelerates as the velocity v of the airflow increases according to v = Q/A.

The velocity of the airflow is significantly increased as travels through the lower section, until it reaches a maximum at the elongate outlet 44. In this way, the tapered lower section enables the low velocity airflow generated by the fan 4 to be converted to a high velocity airflow at the outlet 44, using only the shape and configuration of the air chamber 16. No additional nozzles or channels are required at the outlet to focus and concentrate the airflow, as this function entirely by the air chamber. As such, parts are reduced and assembly is simplified.

The walls 20, 22, and 18 of the air chamber 16 all reduce to and meet at the outlet 44, with the lower edge of each of the walls defining the peripheral edge of the outlet 44. It has been found that this arrangement concentrates the airflow in the most efficient manner, with all of the airflow big channelled directly to the outlet. This improves on arrangement of the prior art, in which the air chamber typically comprises parallel walls which meet at a flat planar base having an opening formed in a part thereof leading to a nozzle is arrangement. As not all the airflow is channelled directly to the outlet, inefficiencies are caused through impact of the airflow with the area of the base surrounding the outlet and the turbulences this creates. The arrangement of the present invention avoids such inefficiencies and provides an optimised arrangement with minimised power consumption.

Claims

CLAIMS1. A hand drying apparatus, the apparatus including a fan, and a housing defining a fan chamber arranged to receive blown air from the fan, wherein the fan chamber comprises an outlet defining the air outlet of the drying apparatus through which air is blown directly to the outside atmosphere, and is configured such that the fan chamber tapers towards the outlet to accelerate air flow therethrough.
2. A hand drying apparatus according to claim 1, wherein the outlet comprises an elongate slot.
3. A hand drying apparatus according to claim 2 wherein the outlet has a length of between 60mm and 80mm.
4. A hand drying apparatus according to claim 2 or 3 wherein the width of the outlet is between 10mm and 20mm.
5. A hand drying apparatus according to any preceding claim wherein the chamber comprises an upper portion which receives the outlet of the fan and a lower portion contiguous with the upper portion, wherein the outlet is arranged at the base of the lower portion with the lower portion tapering towards the outlet.
6. A hand drying apparatus according to any preceding claim wherein the base of the housing defines and is equal in size to the outlet.
7. A hand drying apparatus of claim 6 wherein the housing comprises a plurality of walls defining the chamber which terminate and have terminal edges which define the peripheral edges of the outlet.
8. A hand drying apparatus of claim 7 wherein at least two of the walls converge towards each other to define a narrowing taper in the direction of the outlet.
9. A hand dryer according to claim 8 wherein the air chamber comprises a front wall section and a rear wall section and the front and rear walls are arranged to converge to define the narrowing taper in the direction of the outlet.
10. A hand dryer according to claim 10 wherein the front wall comprises a lower portion which extends substantially vertically and the rear wall comprises a lower portion which slopes downwardly and forwardly towards the front wall to define the taper.ic
11. A hand drying apparatus of claim 8 wherein the taper extends to and terminates at the outlet.
12. A hand drying apparatus substantially as hereinbefore described with reference to, and/or as shown in figures 1 to 3.