Patent Application
20160108924
The present invention relates generally to the field of lawn, leaf and turf blowers, and specifically to battery powered backpack blowers.
In general, backpack leaf blowers are well known, especially in the commercial turf care industry. Most such backpack blowers are gas powered, that is, they have a gasoline engine that powers the blower. In such gas powered blowers, the gasoline engine needs to be very small and light, in order to fit into the backpack form factor. Accordingly, most such backpack blowers have air-cooled 2-cycle engines. Such blowers are often very noisy. A typical gas backpack blower will spin a small fan at about 9,000-10,000 rpm. Such a blower will generally deliver about 500 cfm at 150 mph out of the tube, and will cause about a 75-84 db noise level at 50 feet of distance. Further, 2-cycle engines run hot and emit a large amount of air pollution, have high operating costs because of the gasoline/oil mixture, and can be difficult to start with a pull string and manual choke lever. Particularly in a commercial setting, where use of such blowers can be all day long, operators can feel sick from the odors and fumes of gas engines, and feel fatigue from the work of starting and carrying the noisy gas-powered blowers. Most operators will do anything they can to avoid using the backpack blowers, in large part because the heat from the user builds up between the user's back and the blower, which leads to substantial discomfort.
One attempt at a solution to the heat and noise, air pollution, hard starting, and high operating cost problems associated with 2-cycle gas engine powered blowers, has been to try electric powered blowers. Some weight can be eliminated if a corded version is used, but the fact that the blower is corded so severely limits the physical range of use that it is impractical for commercial applications. And conventional handheld cordless versions are much smaller, and generally have a small battery that will only run 9-12 minutes at top speed, requiring constant recharging with the delays and inefficiencies associated with the charging. At the same time, even electric powered blowers have not solved the problem of noise, as the fans they have used to move the air have been at least as much a source of the noise as has been the gas powered engines. Most hand-held battery-operated cordless blowers spin a very small ducted fan at about 18,000-22,000 rpm. Most hand-held battery-operated cordless blowers move air at about 400 cfm at a maximum speed of about 130 mph, and most such cordless blowers cause about 65-70 db of noise at 50 feet of distance.
The present invention relates to improvements over the apparatus described above and to solutions to some of the problems raised or not solved thereby.
The invention provides a backpack blower, having a fan frame, with a bottom plate and a motor plate. The motor plate has an opening of a certain area which functions as an air inlet. The bottom plate and motor plate are connected to and separated by a side wall, and both are generally ring shaped, except having an air outlet area. A fan assembly, positioned within the fan frame, has a bottom ring and a top ring, which are spaced apart from each other by a plurality of vanes. Each vane is angled and curved substantially the same as all the other vanes with respect to the center of the bottom ring. A motor is provided to rotate the fan assembly within the fan frame, and thus move air from the air inlet to the air outlet. A removable battery pack has electrical connectors for mating with electrical connectors mounted to the fan frame. A controller is electrically connected to the motor and to the battery pack, for using power from the battery pack to energize the motor and thus rotate the fan to move air from the air inlet to the air outlet. A harness frame is connected to the fan frame and has an opening in air flow communication with the air inlet, so that, when the motor is rotating the fan assembly, air is drawn in through the harness frame opening. With the harness frame positioned adjacent to the operator's back, the air flow through the harness frame opening has the effect of cooling the operator. A main cover with air intake openings is connected to the motor plate and to the harness frame and positioned over the motor plate opening.
Other objects and advantages of the invention will become apparent hereinafter.
Referring now to the drawing figures, the invention provides a backpack style leaf and lawn blower 10. In the embodiment shown, the blower 10 includes a fan frame 12. Fan frame 12 includes a substantially flat bottom plate 14, which is generally circular except for an outlet area 14a which will be explained below. Fan frame 12 also includes a substantially flat motor plate 16 which is also generally circular except for its matching outlet area 16a. Motor plate 16 is positioned above and substantially parallel to bottom plate 14, with the outlet areas 14a and 16a aligned over each other. The bottom plate 14 and the motor plate 16 are maintained at a predetermined separation from each other by a side wall 18 mounted substantially perpendicular to, and at the periphery of, the bottom plate and motor plate. The centers of the bottom plate 14 and motor plate 16 form a line substantially parallel to the side wall 18.
The motor plate 16 has an opening 20 at its center which is generally round, the diameter of which about half of the diameter of the motor plate itself, except that there are motor mounting arms 21 extending generally radially inward from the inner edges of the opening.
The embodiment shown includes a centrifugal fan assembly 22 with forward curved vanes 32. The fan assembly 22 is positioned within the fan frame 12, that is, between the bottom plate 14 and the motor plate 16, and within the side wall 18. The fan assembly 22 includes a bottom ring 24, and a top ring 26. The rings 24, 26 have similar diameters. Top ring 26 has a top ring opening 30 at its center, the diameter of which opening is about 70% of the outside diameter of the top ring. The plane of the top ring 26 is spaced apart from and parallel to the plane of the bottom ring 24, held at a predetermined spacing by a number of the vanes 32, spaced generally equally about the circumference of the rings. The embodiment shown in
As shown in
The side wall 18 does not entirely enclose the fan assembly 22, instead having an outlet 44 which allows escape of the air being moved by the fan assembly, and in fact, use of the blower 10 as a blower. The area of the outlet opening is about 25% of the area of the motor plate opening 20, so as to provide proper air flow and pressure. As shown in
Mounted to the outer surface of the motor plate 16 is a main cover 52. Considering as the front of the blower 10 the outlet 44, and that the direction of air flow from the outlet is out the front of the blower, the bottom end of the main cover 52 is connected to the motor plate 16 at the back of the blower. The main cover 52 acts as a guard, rising at a forward angle and thereby covering the motor 34 and the larger motor plate opening 20, and being perforated with small openings 52b so as to still permit entry of air into the motor plate opening, as shown by arrows 53 (
A harness frame 58 (shown in isometric isolation in
The power source for the blower 10 is a battery pack 64 which is easily removable and replaceable, in an opening 52a provided for that purpose in main cover 52. Some of the drawing figures show the opening 52a with the battery pack 64 having been removed, so as to show the battery pack support plates 66, 68 under the main cover 52. As shown in
Given the generally horizontal orientation of the fan assembly 22 and the straight-line orientation between the outlet 44 and the hose 46, the invention provides a blower 10 that produces higher static pressure and has much quieter operation than prior backpack leaf blowers, but still has very good air flow. Blower 10 generally has a top speed of about 4700 rpm, compared to, as described above, 9,000-10,000 rpm for commercial gas backpack blowers and about 18,000-22,000 rpm for most hand held cordless blowers. Fan assembly 22 will deliver 504 CFM at 150 mph out of the tube with 58 db noise level at 50′ distance. As stated above, a typical gas backpack blower that delivers 500 cfm at 150 mph out of the tube causes about a 75-84 db noise level at 50′ distance. Since noise doubles for every 6 db change, blower 10 is about 3-4 times quieter than a conventional gas blower. Most handheld battery-powered cordless blowers move about 400 cfm of air at a maximum of about 130 mph, and cause about 65-70 db of noise—still 2-3 times louder than blower 10, with much less air movement performance. As described above, these hand held blowers also have a disadvantage in that their small battery will only run 9-12 minutes at top speed. With its large battery pack 64, blower 10 will run over 60 minutes at the best speed of the handheld blowers, or about 45 minutes at its top speed of 150 mph. Run time such as that is about the same as in a commercial gas backpack blower using a full tank of gasoline. Further, as shown in
While the apparatus hereinbefore described is effectively adapted to fulfill its intended objects, it is to be understood that the invention is not intended to be limited to the specific preferred embodiments set forth above. Rather, it is to be taken as including all reasonable equivalents to the subject matter described.
This application is based on and claims priority from U.S. Provisional Patent Application No. 62/065,079 filed on Oct. 17, 2014, which is incorporated herein by reference in its entirety for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62065079 | Oct 2014 | US |
