A debris blowing apparatus

Abstract: A debris blowing apparatus (1) with a motor (2), a fan (4) driven by the motor (2), an inlet (6) to the fan (4) and an air outlet (8) from the fan (4). A portion (10) of the air which is emitted through the outlet (8) is recycled through a metering aperture (12) into the air inlet (6) to maintain a constant load on fan (4) whilst varying the air output.

Description: This invention relates to a debris blowing apparatus, in particular a garden debris blowing apparatus used for blowing debris into piles ready for collection. The apparatus is preferably of the kind which may be used either in a vacuum mode, to suck debris into the apparatus, or in a blowing mode, to discharge a stream of air so that debris can be blown into piles, ready for collection. Known forms of apparatus of this kind, for example, that disclosed in US Patent No. 4,694,528, have a motor which is located in a housing and which drives a fan. An air inlet is provided in front of the fan and an air outlet is located radially of the fan. Differing arrangements of ducts are used to direct the air flow to provide the vacuum and blowing mode. In blowing mode, the output of the fan can be varied to provide a high blow or a low blow. A known system for controlling the strength of the blow which is disclosed in US 4,694,528 does so by varying the input of air to the fan by having a rotating disc which is disposed in front of the inlet to the fan. The disc has holes in it, the size of which can be varied by rotation of the disc in order to vary the air blowing speed. Such systems have the disadvantage of varying the load on the motor as the input to the fan varies and the fan speeds up or slows down. The closest piece of prior art is FR2300535. FR2300535 discloses the features of the pre-characterising part of claim 1. According to the first aspect of the present invention there is provided a debris blowing apparatus comprising a housing in which is located: a motor; a fan driven by the motor; an air inlet to the fan, an air outlet from the fan, a metering aperture through which air expelled from the outlet can pass, an aperture cover for selectively covering the metering aperture, and a blower duct, a first end of which communicates with the air outlet so that, in use, air which does not pass through the metering aperture travels along the blower duct and exits the housing from a second working end of the blower duct characterised in that the metering aperture provides a passageway within the housing to the inlet through which the air expelled from the outlet can be recirculated into the air inlet. Preferably, the aperture cover is a sliding cover. The sliding cover may be operated by a rack and pinion arrangement. The apparatus may include a suction duct, a first end of which communicates with the inlet to the fan when the apparatus is used in vacuum mode so that air is drawn into a second working end of the suction duct along the suction duct and through the fan. Debris is carried by the air flow into and along the suction duct and through the fan to a collection point. According to the second aspect of the present invention, there is provided a debris collecting apparatus comprising a debris blowing apparatus as previously described which may include a suction duct the working end of which includes a means for generating an entrained air flow in the suction duct by using air expelled from the outlet by the fan. The entrained airflow draws debris into the working end of the suction duct and transports along the suction duct to a collection point. Specific embodiments of the present invention are now described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a debris collecting apparatus in accordance with a first embodiment of the present invention with the recycled air flow depicted by arrows; Figure 2 is a cross-section of the debris collecting apparatus of Figure 1 with no air recycling; Figure 3 is a cross-section of a debris collecting apparatus in accordance with a second embodiment of the present invention in blowing mode with the recycled airflow depicted by arrows; and Referring to Figures 1 and 2, a debris collection apparatus 1 has a motor 2 which drives a fan 4. Air enters the apparatus 1 through a air vents 6 and is drawn into the fan 4 through an air inlet 7 in front of the fan 4. The air is expelled by the fan 4 radially and is directed through an air outlet 8. The apparatus 1 has a blower duct 20 through which the air from the outlet 8 travels. The blower duct 20 has a flap 36 at an opening 38 at its working end. The flap 36 is pivotable between two positions. In a first position (shown in solid line in Figures 1 and 2) the air flow is directed from the opening 38 of the blower duct 20 back along a collecting duct 30 which runs parallel to the blower duct 20. A second position of the flap 36 (shown in broken lines in Figures 1 and 2) directs the air away from the collecting duct 30 and the apparatus 1 functions as a blower. In the first position of the flap 36, the debris collecting apparatus is arranged in a vacuum mode. The air exiting through the outlet 8 from the fan 4 is directed by the blower duct 20 and the opening 38 at its working end. The flap 36 directs the exiting air back along a collecting duct 30 running parallel to the blower duct 20. An opening 32 at the working end of the collecting duct 30, adjacent to the opening 38 of the blower duct 20, provides an inlet for the debris which is sucked into the collecting duct 30 by the air current exiting from the blower duct 20. The debris passes along the collecting duct 30 into a collecting sack 22. In this arrangement the debris does not pass through the fan 4. In the second position of the flap 36 (shown in dotted lines) the debris collecting apparatus is arranged as a blower. Air is sucked into the fan 4 through the air inlet 7 via air vent 6 in an inlet housing 26 and is expelled through the air outlet 8 and out of the blower duct 20. Air which exits from the blower duct 20 (as shown by the dotted arrow in Figure 1) is used to blow debris into a desired position for collecting. An aperture 12 is provided in a wall 24 between the blower duct 20 and the inlet housing 26. The aperture 12 is metered by a sliding cover 28 operated by a knob 18 external to the housing 26. The knob 18 operates the cover 28 via a rack and pinion arrangement 14, 16. The toothed pinion 16 is rotated by the knob 18 causing the pinion 16 to interact with the rack 14 disposed on the sliding cover 28. A variable portion of the air exiting through the blower duct 20 is recycled through the metering aperture 12 and re-enters the fan 4. The amount of air 10 being recycled through the aperture 12 is varied by the operation of the knob 18. If a low blow is required with a low air output, the aperture 12 is opened to recycle the maximum amount of air possible through the aperture 12 so that less air travels down to the working end of the blower duct 20. The amount of air being drawn by the fan 4 through the air vents 6 is therefore reduced as there is less demand on the air vents. If a high blow is required, with a high air output, the aperture 12 is closed and all the air exiting from the fan 4 is directed to the working end of the blower duct 20. Thus, the amount of air drawn through the air vents 6 increases. As the size of the aperture 12 is varied the amount of air being drawn by the fan through the air vents 6 changes to compensate for the change in the volume of recirculated air. However, the total amount of air being drawn by the fan hardly changes so the load on the fan and thus the motor remains constant. A second type of debris collecting apparatus is shown in Figure 3. Figure 3 shows the apparatus in blowing mode. A housing 40 houses a motor (not shown) which drives a fan 4' via a drive shaft 42. The fan 4' draws air through the air vents 6' and air inlet 7' and expels air radially through air outlet 8' and blower duct 20'. Air exits the blower duct 20' at its working end 44 and can be used to blow debris into piles. The inlet housing 26' is formed integrally with the blower duct 20' to form a blower attachment. The metering aperture 12' and cover 28' are located on a wall 24' between the inlet housing 26' and the blower duct 20' and works in a similar way to that described in relation to Figures 1 and 2. The blower attachment is releasably attachable to the motor fan housing 46.

Claims: A debris blowing apparatus comprising a housing in which is located: a motor (2); a fan (4) driven by the motor (2); an air inlet (7) to the fan (4), an air outlet (8) from the fan (4), a metering aperture (12) through which air expelled from the outlet (8) can pass, an aperture cover (28) for selectively covering the metering aperture (12), and a blower duct (20), a first end of which communicates with the air outlet (8) so that, in use, air which does not pass through the metering aperture (12) travels along the blower duct (20) and exits the housing from a second working end of the blower duct (20) characterised in that the metering aperture (12) provides a passageway within the housing to the air inlet (7) through which air expelled from the outlet (8) can be recirculated into the air inlet (7). A debris blowing apparatus as claimed in claim 1, wherein the metering aperture (12) has a sliding cover. A debris blowing apparatus as claimed in claim 2, wherein the sliding cover is operated by a rack and pinion arrangement (14,16). A debris blowing apparatus as claimed in any one of the preceding claims, wherein a knob (18) on the outside of the apparatus controls the aperture cover. A debris blowing apparatus as claimed in any one of the preceding claims, wherein the apparatus additionally comprises a suction duct a first end of which communicates with the inlet to the fan (4) when the apparatus is used in vacuum mode so that air is drawn into a second working end of the suction duct along the suction duct and through the fan to a collection point (22). A debris collecting apparatus which comprises a debris blowing apparatus as claimed in any one of claims 1 to 4, wherein the apparatus includes a suction duct which has a working end (32) into which, in use, debris enters and said end includes a means (38) for generating an entrained airflow in the suction duct by using air expelled from the outlet by the fan.

Inventors: SADLER JOHN, WEBSTER CRAIG, SADLER, JOHN, WEBSTER, CRAIG
Applicants: BLACK & DECKER INC, BLACK & DECKER INC.
Application year: 1996
Main classification: A47L5
IPC codes: A47L5