Abstract:
Blower attachment that attaches to a drive unit having a long driveshaft, such as, for example, a lawn trimmer typically used in garden and landscape maintenance. The blower attachment has a housing and an impeller that rotates therein. When coupled together, the drive shaft drives the impeller in the blower attachment. The rotating impeller causes an intake of air through an inlet in the housing. Air is expelled laterally from the housing through air outlets in the housing, blowing a stream of air horizontally across the ground.

Description:
BACKGROUND INFORMATION 
       [0001]    1. Field of the Invention 
         [0002]    The innovation relates to the field of motorized blower devices for gardening and landscape maintenance. Such blower devices are used, for example, to blow fallen leaves over the ground and thereby clean the ground of fallen leaves. 
         [0003]    2. Description of the Prior Art 
         [0004]    Prior-art motorized blower devices have an internal combustion engine and a blower arranged directly adjacent to each another. The operator generally carries such blower devices by its long arm or on his/her back. The expelled air is directed toward the ground through a pipe or hose attached to the blower, so that the generated airflow reaches the material on the ground that is to be blown, such as debris. 
         [0005]    In addition, motorized equipment having a long drive shaft are known for use in gardening and landscape maintenance. An example of this type of motorized device is shown schematically in  FIG. 1 . These motorized devices have a motor that drives a drive shaft that is usually much longer than one meter. Generally, the drive shaft is housed in a tube, in order to eliminate the risk of injury to the user. The aforementioned motorized devices are used, for example, in motorized lawn trimmers. In this case, a cutting tool is coupled to the free end of the drive shaft and rotated by the drive shaft. 
         [0006]    Against this backdrop, the object of the present innovation is to offer improved devices for blowing debris in gardening and landscape maintenance. In particular, devices are to be offered that do not exhibit the aforementioned disadvantages. The innovative devices should especially provide an economical blower device that generates less noise and/or transmits fewer vibrations to the user than the prior-art blower devices. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The invention is a blower attachment for use with a gardening and landscape maintenance drive unit having a long drive shaft. The blower attachment according to the invention comprises a housing and a rotatable impeller therein. The housing has an appropriately arranged inlet for drawing in air and an appropriately arranged outlet for expelling air. The impeller is constructed such that, during rotation, air is drawn through the inlet of the housing and expelled through the outlet of the housing. Furthermore, the blower attachment is coupled to the drive unit in such a way that the impeller is rotated by the rotating drive shaft of the drive unit. 
         [0008]    The innovation achieves the desired advantages. Since the blower attachment itself does not contain a motor, it can be manufactured relatively inexpensively, for example, of plastic. The blower attachment according to the invention is couplable to drive units having a long drive shaft, such as are commonly used in gardening and landscape maintenance. Coupling the blower attachment to a conventional drive unit eliminates the costs for a motor that is used only for blowing—and increases the efficient use of existing drive units. In this way, the blower attachment according to the invention affords cost savings. In particular, the blower attachment according to the invention is couplable to a motorized lawn trimmer by means of a drive unit having a long drive shaft. Diverse cutting tools are couplable to a series of such conventional lawn trimmers, and the blower attachment according to the invention can be coupled to such units, instead of the cutting tool. 
         [0009]    Furthermore, the innovative blower attachment reduces noise. The motor and blower are not directly adjacent each another, but rather, are separated from each other by the drive shaft, which is generally over one meter long. Thus, the blower does not intensify the noise generated by the motor. Consequently, less noise is produced than with prior-art blower devices. 
         [0010]    In a preferred embodiment, the impeller of the blower attachment has an axle or a shaft. Preferably, when coupling the blower attachment to the drive unit, this axle is coupled to the drive shaft. When coupled to the drive unit, the rotation of the drive shaft thus transmits rotation to the impeller via this axle. In another embodiment, however, it is also possible to construct the impeller without this axle, but with a center through-bore for receiving a drive pin or the drive shaft. The manufacture of this blower attachment is especially simple and cost-effective. In this embodiment, the impeller itself is not mounted, until it is screwed onto the drive pin or the drive axle. 
         [0011]    According to another preferred embodiment, the impeller is mounted in the housing. If the impeller has an axle, the impeller may be mounted via the mounting of the axle in the housing. This arrangement results in quieter impeller operation. As already discussed, it is also very advantageous with regard to especially cost-effective manufacturing, that the impeller itself does not have a shaft, but rather only a bore or a receptacle for the drive pin or the drive axle. 
         [0012]    In another preferred embodiment, the air inlet and air outlet of the housing, as well as the impeller, are constructed such that the air of the impeller rotation is drawn in the axial direction and expelled in the radial direction. In this way, the blower attachment functions as a radial blower. The blower attachment can thus be advantageously constructed such that, after coupling the attachment to the drive unit, the rotational axis of the impeller basically extends perpendicular to the ground during operation. A radial blower attachment constructed in this manner enables air to be drawn from above along the rotational axis of the impeller and then expelled perpendicularly to the rotational axis and thus parallel to the ground. Drawing air from above is advantageous because this prevents debris lying on the ground from being drawn into the blower attachment. 
         [0013]    In another preferred embodiment, the housing of the blower attachment has a cover and a base. When using the coupled blower attachment, the base faces the ground and the cover faces away from the ground. The air inlet of the housing, as well as the coupler for coupling to the drive unit, is located in the cover. With regard to the coupling of the blower attachment to the drive unit, however, there are additional advantageous embodiments, which will be described below. Referring again to the air inlets in the cover, this construction also keeps the air inlet as far as possible from the ground debris during use of the blower attachment, which prevents the air inlet from drawing this debris into the blower attachment. 
         [0014]    In yet another preferred embodiment, the air inlet in the cover surrounds the coupler annularly. This is achieved, for example, by a ring of air slots around the coupler. This embodiment keeps the air inlet a substantial distance away from the ground. Placing the air inlet in the cover of the housing and close to the rotational axis of the impeller provides the greatest protection against drawing debris into the air inlet. 
         [0015]    In yet another preferred embodiment, the impeller is constructed as a disk, on which the impeller blades are essentially arranged standing perpendicular to the plane of the disk and in the form of a ring. This embodiment enables a flat construction of the blower attachment. Preferably, the blower attachment is constructed in such a way that the disk is essentially parallel to the ground when the blower attachment is in use. The disk is suitably located on the side of the impeller facing the housing base. The impeller blades then stand on the side of the disk facing the housing cover. This allows the air to be drawn from above. 
         [0016]    In yet another preferred embodiment, the blower attachment is constructed such that, rotation of the impeller causes the air to be drawn on the inside of the blade ring and expelled on the outside of the blade ring. In this way, the air is drawn near the rotational axis of the impeller. 
         [0017]    Furthermore, the object according to the present innovation is fulfilled by a blower device that is constructed as a drive unit with a long drive shaft and a blower attachment as previously disclosed. In a blower device according to the invention, the blower attachment is coupled to the drive shaft of the drive unit. 
         [0018]    The innovative blower device achieves the desired advantages. The drive unit with the long drive shaft is decouplable from the blower attachment and usable for other purposes in gardening and landscape maintenance. Furthermore, the motor and blower are separated from each other by the long drive shaft on the blower attachment according to the invention, which reduces the noise that is generated. In addition, during use, the motor is separated a distance from the operator, thereby reducing the exposure of the operator to vibrations. 
         [0019]    In a preferred embodiment, a drive head to which the blower attachment is coupled is provided on the free end of the drive shaft. Inside the drive head, the rotation of the drive shaft is converted into a rotation, the rotational axis of which is at an angle to the drive shaft. The rotational axis of the impeller of the blower attachment and the drive shaft thus preferably form a blunt angle. 
         [0020]    In another preferred embodiment, the drive components of a motorized lawn trimmer are used as the drive unit of the blower device according to the invention. These drive components essentially have the form of a drive unit with a long drive shaft. To construct the blower device according to the invention, the blower attachment is coupled to the drive shaft of the motorized lawn trimmer, in place of the cutting tool. This provides the advantage, that the drive components of a lawn trimmer can also be used for another purpose, namely, for constructing a blower device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. 
           [0022]      FIG. 1  is a perspective view of a conventional gardening and landscape maintenance power device having a long drive shaft. (Prior Art) 
           [0023]      FIG. 2  is an external, perspective view of a blower attachment according to the invention, 
           [0024]      FIG. 3  is a cross-sectional view of a blower attachment according to the invention that is attached to a power device. 
           [0025]      FIG. 4  is an exploded view of a blower attachment according to the invention. 
           [0026]      FIG. 5  is a perspective view of a blower device according to the invention, showing the blower attachment coupled with a drive unit. 
           [0027]      FIG. 6  is a cross-sectional view of an embodiment of the blower attachment according to the invention. 
           [0028]      FIG. 7  is a cross-sectional view of an embodiment of the blower attachment according to the invention. 
           [0029]      FIG. 8  is an exploded view of an embodiment of the blower attachment according to the invention. 
           [0030]      FIG. 9  is a cross-sectional view of the embodiment of the blower attachment of  FIG. 8 . 
           [0031]      FIG. 10  is an exploded view of an embodiment of the blower attachment according to the invention. 
           [0032]      FIG. 11  is a cross-sectional view of an impeller blade of the blower attachment of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    The present invention will now be described more fully in detail with reference to the accompanying drawings, in which the preferred embodiments of the invention are shown. This invention should not, however, be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be complete and will fully convey the scope of the invention to those skilled in the art. 
         [0034]    In order to understand the innovation,  FIG. 1  shows a conventional gardening and landscape maintenance drive unit  50  with a long drive shaft  52 . Such drive units  50  usually have an internal combustion engine or an electric motor  54 , which rotates a drive shaft  52 , that is typically over one meter long. To prevent injuries to users, the drive shaft is usually sheathed in a stationary protective tube  56 . The protective tube  56  prevents the user from coming into direct contact with the rotating drive shaft  52 . For greater ease of use, handles  58  may be mounted on the protective tube  56 . A drive head  60 , which allows a change in the rotational direction, is provided on the free end of the drive shaft  52 . 
         [0035]    The drive unit shown in  FIG. 1  is used especially in motorized lawn trimmers. With such lawn trimmers, the cutting tool, for example, a rotating nylon string or a rotating blade, is attached to the free end of the long drive shaft. 
         [0036]      FIG. 2  shows an external view of the innovative blower attachment  10 . An inlet  22  for drawing in the blower air is located on the top of the housing  20 . The inlet  22  is formed by a ring of air slots surrounding a coupler  28  for coupling the attachment to the drive unit  50 . An outlet  23  for expelling the blower air is located on the right side of the housing  20 . The arrangement of the inlet  22  and outlet  23  shown in  FIG. 2  allows the air to be drawn from above and expelled horizontally across the ground when the blower attachment is used. The close proximity of the inlet  22  to the coupler  28  and, at the same time, the large distance between the inlet  22  and the ground prevents the debris on the ground from being drawn into the inlet. Furthermore, the construction of the inlet  22  as a ring of air slots prevents larger objects from being drawn into the housing, since the air slots act like a sieve. 
         [0037]      FIG. 3  shows a cross-section of a blower unit  1000  according to the invention, comprising the blower attachment  10  and the drive unit  50 . The blower attachment  10  is attached to the drive unit  50  by means of a long drive shaft  52 . The only part of the drive unit shown is the free end of the long drive shaft  52  with a drive head  60 . The rotational axis of the drive head  60  is angled relative to the rotational axis of the drive shaft  52 , by means of a ball joint or a gear. The impeller has a rotational axis RA. A directional change of the rotational axis of the drive unit  50  thus occurs in the drive head  60 . The housing  20  of the blower attachment  10  shown in  FIG. 3  has a cover  25  and a base  26 . The air inlet  22 , formed as a ring of air slots, is located in the cover  25 . An impeller  30  is located inside the housing. The impeller  30  is constructed as a disk  34  on which impeller blades  36  are essentially arranged perpendicularly to the disk. The disk  34  of the impeller  30  has a curved cross-section, with a slight elevation  34 A in the center. This construction of the impeller with the curved cross-section and elevation in the center is merely one embodiment. In another construction of the impeller, the top and bottom sides of the impeller can essentially be flat (except for the recess in the middle area), for example, to make production of the impeller more cost-effective. In the outer region, the impeller blades  36  almost completely fill the cross-section of the housing, so that only a small space exists between the internal wall of the housing  20  and the impeller  30 . The impeller  30  has a center shaft  32  that is mounted on a bearing  33  in the housing  20  of the blower attachment  10 . The shaft  32  of the impeller  30  is attachable to the drive head  60 , such that the impeller  30  is rotatable by the long drive shaft  52 . Due to the directional change in the drive head  60 , the shaft  32  is at an angle to the drive shaft  52 . As shown in other embodiments, it is not necessary to construct the impeller  30  with a shaft  32 ; rather, the impeller  30  may have a bore or a recess in the center, such that the drive shaft or the drive pin of a drive unit extends into this recess and causes the impeller  30  to rotate when this drive pin rotates. 
         [0038]    For proper operation of the blower attachment  10 , one sweeps the bottom of the housing  26  over the ground, so that the air that is drawn in from above through the inlet  22  and is expelled horizontally directly across the ground, so as to blow the debris on the ground. 
         [0039]      FIG. 4  shows an exploded view of the blower attachment  10  according to the invention. The air inlet  22  and the coupler  28  for the drive unit  50 , as well as the top of the outlet  23 , are located in the cover  25  of the housing  20 . The impeller  30  is constructed as a single disk  34  on which the impeller blades  36  are arranged standing essentially perpendicular in the shape of a ring. The disk  34  of the impeller is elevated in the middle and reinforced, i.e., made of thicker material, in this center area, to provide good interference fit with the shaft, by means of which the impeller  30  is rotated. Of course, this embodiment is only one example; the impeller  30  may be constructed, for example, essentially flat or level on the top or bottom side. 
         [0040]      FIG. 5  shows a perspective view of the blower device according to the invention. The blower attachment  10  according to the invention is coupled to the drive unit  50 , which has a long drive shaft  52 . During operation, the air is drawn from above through the inlet  22  in the cover  25  of the housing  20  along the rotational axis RA of the impeller  30 , and expelled horizontally over the ground perpendicular to the rotational axis  32  of the impeller  30 .  FIG. 5  clearly shows that, due to the long drive shaft  52 , the motor  54  of the drive unit  50  and the blower attachment  10  are spaced far apart, so that the blower does not intensify the noise of the motor. 
         [0041]    The desired advantages are achieved with the aforementioned innovation. The blower attachment  10  according to the invention is cost-effective to manufacture, since it does not contain a motor. For example, it can be made relatively inexpensively of plastic. Producing the attachment in plastic also results in a relative weight reduction, so that the blower attachment or the blower device is easy and comfortable to use. Coupling the attachment  10  to a drive unit  50  with a long drive shaft also has the advantage of spacing the blower and motor far apart. The long drive shaft  52  also expands the effective range of the blower device, so that the operator can reach even more remote or hard-to-reach spots with the blower attachment or the blower device. The invention makes it possible to use conventional drive units with a long drive shaft that are typically found in gardening and landscape maintenance as a blower. 
         [0042]    The drive shaft  52  drives a splined drive pin  37 , shown in  FIG. 4 , or the splined drive shaft, respectively, in rotational motion. When the blower attachment  10  is coupled to the drive unit, this drive pin  37  meshes into a central bore  38  of the impeller  30 , causing the impeller to rotate. The impeller  30  is connected to the drive pin  37  by means of a screw  39  when the blower attachment  10  is coupled to the drive unit, i.e., the screw  39 , which actually is a component of the drive unit, threads into a threaded opening provided in the drive pin  37 . 
         [0043]    The base  26  has an opening  40  through which the screw  39  can be threaded or unthreaded. 
         [0044]    An adapter system can be used for a simple and inexpensive means of fastening of the blower attachment to the drive unit  50 , whereby an adapter ring (not shown) is fastened to the side facing the blower attachment  10  and a corresponding construction of an adapter mating part is mounted on the cover  25  of the blower attachment  10 . The blower attachment can then be fastened to the adapter ring that is attached to the drive head  60  by means of the adapter mating part affixed to it, for example, by screwing or locking, or by using a bayonet catch. The use of an adapter fastening system is advantageous, because it allows the blower attachment  10  to be very quickly removed from, or fastened to, the drive unit without, for example, requiring the use of a tool. 
         [0045]    The adapter ring fastened to the drive head  60  corresponds in construction to that of the drive head  60 , i.e., it can be constructed according to the various embodiments of the device, whereby only one embodiment of the adapter mating part provided on the cover  25  is required. Thus, particularly when a bayonet catch system is used between the adapter ring, on one side, and the adapter mating part, on the other, one can achieve both ease of operation and an inexpensive means of fastening the blower attachment  10  to the work device, especially if the adapter ring and adapter mating part are, for example, made of plastic. It is important that the use of an adapter enable one to attach the recommended blower device to all drive units, so that the recommended blower device may be used universally. 
         [0046]      FIG. 6  shows another embodiment of the innovation that relates especially to the fastening of the blower attachment  10  to the drive head  60 . In this embodiment, the drive pin  37  of the drive head  60  fits into a splined sleeve  75  of the blower attachment  10 . This splined sleeve  75  corresponds in form to the external form of the drive pin  37 , so that, when the drive pin  37  rotates, the splined sleeve  75  and the impeller blades arranged on it also begin to rotate. The impeller  30  is connected to the drive pin  37  by means of a wing nut  70  or other appropriate fastening device, whereby the wing nut  70  may be screwed into a threaded bore in the drive pin  37 . This embodiment does not include an additional mounting of the impeller  30  in the region of the drive pin, in order to keep the production costs of the blowing attachment  10  as low as possible and the portion of blower attachment  10  parts that are made of plastic as high as possible, so that these parts can in turn be produced inexpensively. In this embodiment, the housing  20  of the blower attachment  10  is fastened to the drive head  60  via an adapter  72 . In the embodiment shown, the adapter  72  grips the lower edge of the drive head  60 . A fixing clamp  79  with two seating surfaces that rest on the top of the drive head when it is in the fixed position clamps the adapter  72  in place. The fixing clamp  79 , which may also have a hood-shaped design, may be connected to the adapter  72 , for example, by a threaded fastener or, as in this embodiment, a bayonet catch. The fixing clamp  79  is manually rotated to its fixed position, something easily done by using the raised grips  82 ,  83 . This holds the adapter ring  72  on the housing  20  up against the drive head  60 , whereby the fixing clamp  79  presses against and is supported by the drive head  60 . 
         [0047]    This therefore enables easy attachment of the blower attachment  10  to the drive head  60 , as well as easy removal of the attachment from the drive head  60 , without the need of a tool. The blower attachment  10  is adaptable to many different constructions of drive heads  60 , by means of various embodiments of the adapter  72 . 
         [0048]    A brush  84  in the area of the outlet serves to loosen leaves that have been trodden into the ground, for example, which can then be picked up by the blowing airflow. The brush  84  also acts as a shock absorber for the blower attachment relative to the ground and prevents the blower attachment  10  from striking the ground too hard when improperly operated. 
         [0049]    Another possible way of connecting the blower attachment  10  to the drive head  60  is to use a positioning part  85 , as shown in  FIG. 7 , which can be affixed to the drive head  60  with a clamping device, for example, the tensioning screw  86 . The tensioning screw is constructed to brace the top of the drive head  60  with a support plate  87 . Like the fixing clamp  79 , the positioning part  86  is another coupling mechanism for holding the drive head  60  and blower attachment  10  together. 
         [0050]    With its two outriggers  88  and  89 , the positioning part  85  engages the curved top edge of an adapter  72 , which in turn is connected to the housing  20  of the blower attachment  10 . Pressing the supporting plate onto the drive head allows the positioning part  85  to lock with the adapter  72  that is connected to the blower attachment  10 . In this embodiment, the adapter  72  may also be adapted to the different measurements of the various constructions of drive heads  60 . Again, only a positioning part is needed to attach different blower attachments to the corresponding drive heads  60 . This embodiment also allows the positioning part  85  to be attached to the blower attachment  20 , or to the adapter  72 , respectively, for example, by turning via the use of a bayonet catch, as in the shown embodiment. Other suitable means of attachment may also be used. 
         [0051]    This embodiment also avoids high production costs by simply fastening the impeller  30  to the drive pin  37 , so that rotation of the drive pin  37  also rotates the impeller  30 . No additional mounting is required in the area of the impeller blade; rather, the blower attachment housing is affixed by means of an external attachment aided by a positioning part  85 . The external attachment is braced, on the one hand, against the housing wall of the drive head  60  and, on the other hand, is attachable to the housing of the blower attachment  10 . 
         [0052]    This embodiment also allows the blower attachment  10  to be fastened to the drive head  60  without use of a tool. Furthermore, this embodiment does not require that the drive head  60  of a conventional drive unit be altered. The operating noise of the blower attachment  10  is substantially reduced by lowering the top edge  36 A of the impeller blades  36  in the area of the inflow air slot, as shown in  FIGS. 6 and 7 . 
         [0053]      FIGS. 8 and 9A  illustrate a further embodiment of the invention, in which a blower attachment  10  is attachable via an adapter  90  to a drive unit that is partially shown in  FIG. 9 . In this embodiment, the adapter  90  comprises two adapter shells  91 ,  92 , which, when assembled as in  FIG. 8 , mate along fold lines  96  to form a sleeve or a continuous recess  93 , which corresponds in length to the entire length of the adapter  90 . As shown in  FIG. 9 , the continuous recess  93  formed by the adapter  90  is adapted to correspond to the outer diameter of the protective tube  56 , within which the drive shaft of the drive unit extends. 
         [0054]    The adapter  90 , along with its adapter shells  91 ,  92 , is thus attachable to the blower-attachment end of this protective tube  56 , so that the protective tube is located inside the recess  93 . The adapter  90  also has a projecting collar  94  on its upper side. The collar has a serrated edge, making it easy to operate or turn manually. Lock tabs  95 ,  96  are provided, spaced apart from the top of the adapter  90 . The tabs are constructed to protrude laterally from the recess  93 . Each adapter shell in this embodiment has a lock tab. The adapter  90  can be made of plastic or metal or any other suitable material. Of course, the adapter  90  can comprise more than the two adapter shells  91 ,  92  shown, which, as is shown in this embodiment, may be constructed as separate components. They may also be connected to each other with a hinge, for example, to provide particularly simple operation or handling. 
         [0055]    The cover  25  of the housing of the blower attachment  10  has a contour  97  in the center, which essentially corresponds to the contour of the underside the adapter  90 , i.e., the bottom contour of the adapter  90  together with the contour of the lock tabs  95  and  96 , as well as of the central part of the adapter shells  91  and  92 . With the adapter  90  positioned as shown in  FIG. 8 , the adapter  90  can now be lowered, so that the lock tabs  95 ,  96  protrude under the bottom of the cover  95 . The adapter  90  can then be rotated 90 degrees, to move the lock tabs  95 ,  96  under the housing wall of the cover  25 , thereby locking or affixing the adapter  90  with the cover  25 . In this way, the adapter  90  allows the blower attachment  10  to be connected to the protective tube  56  of the drive unit. 
         [0056]    The recess  93  is a continuous opening extending the entire length of the adapter  90 . The drive pin  37 , or, more generally, the drive axle of the drive unit, extends all the way through the adapter  90 . When the adapter  90  is mounted, the drive pin or the drive shaft, respectively, extends through the housing of the blower attachment  10  and all the way through the impeller  30 , which itself is driven by this drive shaft or the drive pin  37 . The impeller is then connected to the drive shaft by means of a screw or other fastening element. For example, as shown in  FIG. 6 , a screw is guided through the impeller itself from the bottom of the impeller and screwed into a recess in the drive shaft. Thus, the impeller is screwed directly onto the drive shaft or drive axle and does not have an additional expensive mounting. 
         [0057]    The blower attachment  10  that is mounted in this way is shown schematically in  FIG. 9 , along with the protective tube  56  of the drive shaft, the adapter  90 , the motor-driven drive pin  37  or the end of the drive shaft, as well as a screw  70 . Conventional drives A and B are schematically illustrated by dashed lines. In the case of the protective tube  56  shown in  FIG. 9 , within which the drive shaft extends, a special construction of this protective tube  56  is exploited in the blower-attachment area, in order to hold the adapter  90 . The two adapter shells  91  and  92  encase the housing provided at the end of the protective tube  56  and allow the blower attachment  10  to attach to the adapter  90  without the use of additional locks, screws, or other lock means. The adapter  90  can, of course, be constructed such, that it may be used with all drive units  50  and the corresponding blower attachments  10 . 
         [0058]    The suggested adapter  90  is particularly advantageous in that it is individually adapted to any desirable drive unit, whereby the external perimeter of the adapter  90  always remains the same, so that the blower attachment  10  may have a uniform construction. While the external perimeter, or, external configuration of the adapter  90  always stays the same, the internal configuration of the adapter  90  must be adapted to the form of the respective drive housing or protective housing  56 . This is achieved, for example, by the appropriate form of injection moulding dies. 
         [0059]      FIGS. 10 and 11  show another embodiment of the blower attachment, in which the blower attachment  10  again comprises a top cover  25  and a bottom cover or base  26 , with an impeller  30  therebetween. Again, the top cover  25  has inlets  22  for the air, which, due to the rotation of the impeller  30 , is expelled through the air outlet  23 . In this embodiment, however, the base  26  also has air inlets  98 , so that air from both the top and bottom of the blower attachment  10 , i.e., through the air inlets of the top cover  25  and the base  26 , is fed to the impeller  30 , which is a two-sided construction in this embodiment. The individual air blades  99  are centrally positioned on an impeller base  100 , i.e., they project beyond the impeller base  100 , upward, in the direction of the top cover  25 , and downward, toward the base  26 . Such an arrangement allows air to be drawn simultaneously through the top cover  25  and the base  26 , thereby achieving very high performance. 
         [0060]    Protection against debris may be installed from underneath. For example, a filter may be provided in the area of the inlet slots  98  on the bottom; tests, however, have shown that the impeller  30  made of polyethylene, for example, is very robust, and no damage to the impeller was found. By introducing air from both above and below, an increase of approximately 20% in air speed at the outlet  23  was determined.