Improvements relating to collection devices

Abstract: The present specification discloses a collection device comprising an elongate duct (3) for conveying loose material towards a downstream region thereof from a collection mouth (7) at an upstream end thereof. An air outlet (23,25) is disposed adjacent the collection mouth (7) and arranged to in use direct an air flow transversely to the longitudinal axis of the duct over a curved, generally convex flow control surface (27,29) of the collection mouth (7) such that at least a portion of said air flow follows said curved surface (27,29) and is directed downstream within said duct.

Description: The present invention relates to a collection device for use in collecting loose material from a surface. More particularly the present invention relates to a collection device for use in collecting loose material such as litter, debris, lawn cuttings and/or fallen leaves. The collection device is primarily for outdoor use though it may equally well be used indoors as and when appropriate. Existing collection devices such as domestic vacuum/suction cleaners are primarily designed for cleaning upholstery and carpets and are not really suitable for use outdoors. They are usually limited by weight, area of suction head and the cross-section of the tube connecting the suction head with a motor-driven fan for providing the suction, and a collection bag. Further, a large motor is required to overcome the various filters which are necessary whilst maintaining sufficient suction to extract/lift dirt, debris etc. and transport it to the collection bag. Known industrial and horticultural vacuum/suction cleaners usually comprise an internal combustion engine, a fan and a collection bag. However, these devices are meant for use outside of a domestic situation and are generally large and expensive, and whilst mobile, they are not versatile. However in both of the above known collection devices the loose material is collected by suction and has to pass through the fan arrangement, and this can and does cause problems with larger items, such as empty drink cans. Further a large amount of suction force is required to lift the loose material, thus necessitating a large, powerful motor which clearly adds to the weight and cost of the collection device. Further known collection devices designed for removing loose material from a fixed surface by means of a stream of air, utilise the stream of air to dislodge and entrain the said material with the stream of air being effectively directed at and bounced off the fixed surface. One such known construction is disclosed in US-A- 1383455 wherein the construction has a collection mouth which is neccesarily engaged with the fixed surface i.e. carpet or ground, so that the stream of air bounced off the fixed surface can only pass into a collection channel, entraining any loose material disturbed by the impact of the stream of air fitting the fixed surface. A similar construction is also disclosed in US-A- 4018483. The aim of the present invention is to provide a collection device which utilises a stream of air so as to lift and collect loose material off a fixed surface, this being in contrast to the known prior art devices wherein the loose material is collected either by suction or by utilising a stream of air to purely disturb and then entrain such loose material. According to the present invention there is provided a collection device for removing loose material from a fixed surface by means of a stream of air, the collection device comprising an elongate duct through which the loose material is conveyed from an upstream end region of the duct defining a collection mouth towards a downstream region of the duct when the collection mouth is disposed in a ready to collect position relative to the fixed surface, a source of pressure air and means for feeding pressure air to one or more air outlets disposed in the region of the collection mouth to provide a stream of air for use in conveying loose material lifted from the fixed surface, into and along the duct, characterised in that an air outlet opens directly into the duct and is located in the region of one end of a control surface, at least part of which control surface is generally convex, the control surface extending downstream of the duct, said air outlet being arranged to direct a stream of air over the control surface whereby the stream of air issuing from the air outlet is directed in a direction transverse of the longitudinal axis of the duct, and is directed within the duct and generally downstream within the duct, when the collection mouth is spaced above the fixed surface, the stream of air issuing from the air outlet inducing an additional flow of atmospheric air into the duct via the collection mouth to assist in lifting loose material from the fixed surface and in conveying the material downstream within the duct. By directing the air flow over a curved flow control surface, at least a portion of the air flow follows the contour of the curved flow control surface by virtue of the boundary layer effect. By having a very smooth curved flow control surface, laminar air flow is achieved and the boundary layer of air adjacent to the surface is very thin. In this instance a streamlined flow of air over the curved control surface results, and at least a major portion of the air flow follows said curved surface and enters said duct. Thus a positive air flow is provided along the duct away from the collection mouth, causing air to be drawn into the collection mouth together with any loose material in the vicinity of the collection mouth. The lifting of any such loose material, e.g. leaves, drink cans, etc., is enhanced by the fact that any such loose material will be near to one particular region of the curved flow control surface and the air thus increases speed in the gap between this one particular region and said material, causing a drop in air pressure in the gap, which drop in pressure pulls the loose material towards the curved flow control surface, i.e. the loose material is lifted off the ground. The loose material is then passed along the duct to a collection container at the downstream region of the duct, by the air flow, and as the duct is merely a passage with no fan or other auxiliary component causing at least a partial obstruction or a tortuous flow path, it can provide a relatively smooth path which facilitates the collection of a large variety of shapes and sizes of loose material. In a preferred embodiment of the present invention said duct is provided with outwardly flaring front and rear edge regions, each of which edge regions is curved and ends in an air flow outlet. Each air flow outlet is connected to a motor driven fan with the outlet being so designed as to direct a flow of air at an inclined angle to the longitudinal axis of the duct, substantially along a smoothly curved surface, into the duct, part of the outlet merging with the smoothly curved surface and said smoothly curved surface merely merging with and continuing as the inside wall of the duct. As previously mentioned at least a major part of the air flow will follow the curved surface and enter the duct due to the boundary layer effect, the remainder of the air flow disturbing the loose material beneath the collection mouth and thus facilitating the loose material being drawn into the duct by the air flow. Whilst the front and rear edge regions of the collection mouth may be provided with curved surfaces and associated air flow outlets, solely the front or rear edge region may be so designed or alternatively one or other side edge regions may be additionally or alternatively so designed, as is required. The collection device is preferably designed so as to be hand-held with the motor driven fan being electrically driven. Alternatively, the device may be mounted on wheels and/or the fan may be driven by alternative power means, e.g. an internal combustion engine. Preferably the collection device is designed so that when it is hand-held, with the collection mouth aligned with the ground in a ready-for-use position, the elongate duct is inclined to the ground. The collection container may be a disposable plastic bag which can be easily detachably attached to the downstream end region of the duct with a filter outlet allowing the air flow to escape adjacent to the container, or alternatively a loose-woven bag may form the collection container obviating the need for a filter outlet. In a modified embodiment of the present invention a controllable air flow outlet is provided so as to allow a flow of air to be directed out from the collection device, as and when desired, preferably in the region of the collection mouth. By guiding the collection device and thus the direction of this flow of air our from the collection device, material to be collected can be disturbed and/or collected together prior to the collection mouth being moved thereover. The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which:- Fig.1 is a perspective view of a presently preferred embodiment of the present invention; Fig.2 is a front view, partially in cross section, of the lower part of the device of Fig.1, which forms a collection mouth; and Fig.3 is a cross-sectional side view of the lower part of Fig.2. The presently preferred embodiment of a collection device of the present invention illustrated in the accompanying drawings, comprises an elongate duct member 1 through which a generally smooth profile duct 3 extends, with a collection head 5 defining a collection mouth 7 at one end region i.e. the upstream end region, of the duct 3, and a collection container 9 detachably secured at the other end region i.e the downstream end region of the duct 3. The collection device includes an electric motor and fan 11 which is mounted on the outside of the duct member 3 and which connects with front and rear edge regions of the collection head 5 via pipes 13 and 15, respectively. The motor 11 and/or pipes 13 and 15 can of course be constructed as an integral part of the duct member 3 and hidden from sight within the duct member 3 to improve the aesthetics of the device. The motor 11 is connected to an electricity supply by a cable (not shown) and switched on and off by a switch provided in a handle 17, the handle 17 enabling the collection device to be moved by hand as desired, to pass the collection head 5 over loose material to be collected. As evident in Figs. 1 and 3, the collection device is designed so that with the collection head 5 aligned with the ground, the duct 3 is inclined to the ground, thereby facilitating entrainment of loose material along the duct 3 as compared to a vertical duct. The collection head 5, as best seen in Figs. 2 and 3 of the accompanying drawings, is generally rectangular with front and rear edge regions 19 and 21 respectively, being each provided with an air outlet 23,25 which is arranged to direct an air flow generally along an adjacent curved surface 27,29, one part 30 of each air flow outlet 23,25 being formed by a continuation of the adjacent curved surface 27,29, to thus cause the air to flow along and against the respective curved surfaces. Due to the boundary layer effect, and the provision of a smoothly curved surface 27,29, laminar and streamlined air flow results so that the major part of the air flow from each outlet 23,25 follows the profile of the respective curved surface 27,29 into the duct 3, the remainder disturbing any loose material located beneath the collection mouth 7 and facilitating entrainment of this loose material into the air flow along the duct 3. Entrainment of loose material into the air flow along the duct 3 is specifically enhanced by the fact that the material to be collected will be closer to one part of a curved surface 27,29 than another when the collection mouth 7 is passed thereover. Thus the air flow through the gap between the material and said close part of the curved surface 27,29 will be increased causing a drop in air pressure in the gap and resulting in the material being drawn nearer to the curved surface, i.e. lifted off the ground, the air flow into the duct 3 carrying the material along the duct. 3. The air outlet 23 at the front edge region 19 of the collection mouth 7, extends as a narrow slot across the width of the collection head 5, and leads from a plenum chamber 31 which is connected to air flow pipe 13. A number of angled baffles 33 are provided in the plenum chamber 31 to provide for an even distribution of the air flow emanating from the pipe 13, across the slot forming the outlet 23. As will be seen in Figs. 1 and 3 of the accompanying drawings, a slidable flap 32 is provided in the outer wall of the plenum chamber 31. Thus, when desired, this flap 32 can be moved to open a blower outlet 32a of the collection device, thereby providing a flow of air away from the collection head 5, which air flow can be used, by guiding the collection device and thus the direction of this air flow, to disturb and/or collect material together before the collection head is moved thereover. As opposed to the slidable flap 32, a hinged flap or any other controllable outlet can be substituted. The air outlet 25 at the rear edge region 21 of the collection mouth 7, also extends as a narrow slot across the width of the collection head 5. This outlet 25 leads from a plenum chamber 35 which is connected to air flow pipe 15. Whilst air outlets and associated curved surfaces are provided in the presently preferred embodiment of the present invention, at the front and rear edge regions of the collection mouth 7, one or other outlets could be omitted or blanked off, as desired. Further, air outlets and associated curved surfaces can be provided on the side edge regions of the collection mouth, additionally or instead of the outlets at the front and/or rear edge regions. Also, the collection mouth can be circular or oval with an outlet and curved surface provided continuously therearound. Further, the duct can be rectangular, circular or oval. The collection container 9 is a loose-woven bag which is detachably mounted on hooks 37 at the other end region of the duct 3, the bag itself acting as an air flow escape filter. Alternatively, a disposable plastic bag can be detachably secured to the other end region of the duct 3 and in this case an air flow escape filter has to be additionally provided. Whilst the motor 11 is described as being an electric motor 11 and this motor powers a fan which draws ambient air through a filter 39, and passes the air to the collection head 5, an internal combustion engine can be substituted to power a centrifugal blower fan, or an air compressor can be alternatively substituted. In operation the air is blown over the or each curved surface in the vicinity of the collection mouth 7, this air tending to cling to the curved surface(s) due to the boundary layer effect and as with an aircraft wing, a drop in pressure is experienced above the curved surface causing an amount of lift to the loose material beneath the collection head 5. The loose material is thus drawn towards the curved surface(s) where it is entrained with the air flow along the curved surface(s) and into the duct 3. The amount of lift is dependent on the radius and nature of the curved surface, the amount of air flow and the speed of air flow. By suitable selection of these parameters, the desired performance for any particular situation can be achieved. Whilst the presently preferred embodiment illustrated in the accompanying drawings is a hand-held and operated device, it is envisaged that wheels or rollers can be provided on large machines for use such as in parks and towns, to collect litter, leaves etc. Whatever the required function, the present invention provides a collection device with a smooth profile duct which is free of any ancillary equipment such as an impeller, thereby obviating any possible obstruction or need for a tortuous path, for the loose material entrained in the air flow in the duct.

Claims: A collection device for removing loose material from a fixed surface by means of a stream of air, the collection device comprising an elongate duct (3) through which the loose material is conveyed from an upstream end region of the duct defining a collection mouth (7) towards a downstream region of the duct when the collection mouth (7) is disposed in a ready to collect position relative to the fixed surface, a source of pressure air and means for feeding pressure air to one or more air outlets (23,25) disposed in the region of the collection mouth (7) to provide a stream of air for use in conveying loose material lifted from the fixed surface, into and along the duct, characterised in that an air outlet (23,25) opens directly into the duct (3) and is located in the region of one end of a control surface (27,29), at least part of which control surface is generally convex, the control surface (27,29) extending downstream of the duct (3), said air outlet (23,25) being arranged to direct a stream of air over the control surface (27,29) whereby the stream of air issuing from the air outlet (23,25) is directed in a direction transverse of the longitudinal axis of the duct (3), and is directed within the duct and generally downstream within the duct, when the collection mouth is spaced above the fixed surface, the stream of air issuing from the air outlet (23,25) inducing an additional flow of atmospheric air into the duct (3) via the collection mouth (7) to assist in lifting loose material from the fixed surface and in conveying the material downstream within the duct. A collection device as claimed in claim 1, wherein said at least one air outlet (23,25) is laterally offset outwardly of the throughflow cross section of the duct (3). A collection device as claimed in claim 1 or claim 2, wherein the duct (3) is substantially unobstructed along its length. A collection device as claimed in claim 1, wherein the or each air outlet (23, 25) is disposed within said collection mouth (7). A collection device as claimed in any one of claims 1 to 4, wherein the or each air outlet (23, 25) is arranged to direct said air flow in a direction which is inclined towards the longitudinal axis of said elongate duct (3). A collection device as claimed in any one of the preceding claims, wherein the or each air outlet (23) leads from a plenum chamber (31), a further controllable air flow outlet (32) leading from the plenum chamber (31) to allow air to flow from the plenum chamber (31) to outside the device. A collection device as claimed in any one of the preceding claims, wherein the or each air outlet (23, 25) is in the form of a narrow slot, one side (30) of which slot is coplanar with the adjacent convex surface (27, 29). A collection device as claimed in any one of the preceding claims, wherein the collection mouth (7) is generally rectangular with the or each air outlet (23, 25) extending as a narrow slot which extends across the width of the collection mouth (7). A collection device according to claim 8, wherein the or each air outlet (23, 25) leads from a plenum chamber (31, 35), a number of angled baffles (33) being provided in the plenum chamber (31) to provide for an even distribution of the air flow across the slot forming the air flow outlet (23). A collection device as claimed in any one of the preceding claims, wherein two such air outlets (23,25) are provided, said air outlets (23, 25) being directed towards each other, located at opposite portions of the collection mouth (7), and arranged to, in use, direct air over respective curved flow control surfaces (27, 29). A collection device as claimed in any one of the preceding claims, the said device being adapted to be hand-held with the said collection mouth (7) aligned with a floor surface or ground constituting the said fixed surface, with the duct (3) then being inclined to the ground or floor surface. A collection device as claimed in any one of the preceding claims, wherein the or each air outlet (23, 25) is in the form of a slot which is aligned with the adjacent peripheral region of the collection mouth (7). A collection device as claimed in any one of the preceding claims, wherein an integral motordriven fan means (11) is arranged to discharge air through the or each air outlet (23, 25). A collection device as claimed in any one of the preceding claims, wherein a removable collection container (9) is arranged to collect and retain loose material which is conveyed towards said downstream region of said duct (3).

Inventors: COATHUPE JOHN EDWARD, COATHUPE, JOHN EDWARD
Applicants: COATHUPE JOHN E, COATHUPE, JOHN EDWARD
Application year: 1991
Main classification: E01H1
IPC codes: E01H1, A01G1, A47L9