a combination blower - vacuum unit 10 of this invention is illustrated in the drawings , and generally comprises a power - driven motor 12 mounted within a portable and relatively lightweight housing 14 formed from an impact resistant plastic or the like . the motor 12 rotatably drives a relatively lightweight and inexpensively - formed impeller 36 for drawing air axially inwardly through an air inlet 50 at a relatively high flow rate , and for discharging the air centrifugally into a circumferentially - formed chamber 58 and then through a tangentially directed air outlet 62 . the motor 12 is suitably mounted within a motor casing 24 forming a part of the unit housing 14 . more specifically , as shown in fig2 the motor casing 24 comprises a generally can - shaped member into which the motor 12 is received . the motor is fixed in position within the casing 24 by a plurality of screws 26 which conveniently also serve to connect a first handle member 28 to the unit housing . the motor 12 is connected at its opposite end to an impeller housing 30 as by another plurality of screws 32 , with the impeller housing 30 comprising a second portion of the unit housing 14 . conveniently , the impeller housing 30 includes a second handle member 31 . the two handle members 28 and 31 enable the entire unit 10 to be easily handled and oriented in any desired position by the individual operating the unit . the motor 12 rotatably drives a drive shaft 34 which carries the centrifugal impeller 36 within the impeller housing 30 . power is supplied to the motor 12 by a power cord 38 secured to the impeller housing 30 as by an appropriate connector . the cord 38 in turn is electrically coupled to an on - off switch 42 carried on the impeller housing 30 and operable to couple electrical power to the motor 12 for operation thereof . conveniently , if desired , the electrical connection includes a variable resistor unit 46 for allowing variable speed control of the motor 12 and resultant variable air flow through the unit . alternately , if desired , the electric motor 12 may comprise a small gasoline - powered engine , or other suitable portable power source . the impeller housing 30 is formed from a pair of complementary housing halves 33 secured together as by screws 37 , and defining the air inlet 50 in close association with the impeller 36 . this air inlet 50 is defined by a cylindrical flange 51 forming an open flow path for axial flow of air into communication with the impeller 36 . a perforate cover plate 52 is receivable over the inlet 50 for preventing the operator of the unit from manually contacting the rotating impeller 36 as well as to prevent large objects from being drawn into communication with the impeller . the cover plate 52 is carried on one side by a hinge 54 including a spring 56 for springably biasing the cover plate 52 to a position overlying the air inlet 50 . the cover plate 52 is thus movable between a position covering the inlet 50 when the unit is operated in a blower mode , and a position opening the inlet 50 when the unit is operated in a vacuum mode as will be described herein in more detail . for added safety , suitable latching means may be provided for positively locking the cover plate 52 over the inlet 50 , such as a screw 53 secured into the impeller housing 30 as shown in fig2 when the unit is operated in the blower mode . the rotating impeller 36 draws air axially inwardly through the air inlet 50 at a relatively high flow rate . this air is centrifugally discharged from the impeller 36 into an annular chamber 58 defined by the impeller housing 30 circumferentially surrounding the impeller . this chamber 58 communicates via an opening 60 within the housing 30 with a tangentially directed tube 61 forming the air outlet 62 for discharge of the impeller - blown air outwardly at a relatively high flow rate through the air outlet 62 . for example , in one embodiment of the invention , the centrifugal impeller 36 was rotably driven at up to about 11 , 000 r . p . m . to provide an air flow rate of about 300 cubic feet per minute . as shown in fig1 and 2 , the blower - vacuum unit 10 is adapted for use in a blower mode with the cover plate 52 in its normal position extending over the air inlet 50 . in this configuration , air is rapidly drawn axially inwardly by the impeller 36 through the air inlet 50 and the perforate cover plate 52 for centrifugal discharge at a correspondingly high flow rate through the air outlet 62 . an elongated nozzle tube 64 has a tapered end 66 for quick , easy , and snug reception into the open end of the tangential air outlet tube 61 , and functions in the blower mode to direct the blown air to the desired surface . conveniently , the opposite end of this nozzle tube 64 may be configured to have an appropriate nozzle geometry for direction of the blown air , or alternately , configured for reception of nozzle ends ( not shown ) of different geometries . the blower - vacuum unit 10 of this invention is quickly and easily adapted for use in a vacuum mode by removing the nozzle tube 64 from the air outlet 62 , and by mounting over the outlet 62 a dust bag 68 or the like comprising a bag formed from a relatively porous fabric or filtering material . as shown in fig4 the dust bag 68 is easily attached to the outlet 62 by means of a strap 70 secured behind a pair of lugs 71 receiving a pair of the screws 37 holding the housing halves 33 together . then as shown in fig3 the nozzle tube 64 is repositioned with its tapered end 66 secured within the flange 51 of the air inlet 50 . in this configuration , the impeller 36 is operable to vacuum material through the nozzle tube 64 into the impeller housing 30 , and then to discharge the material into the dust bag 68 . if desired , suitably geometried nozzle ends ( not shown ) may be provided for connection to the nozzle tube 64 for operating in the vacuum mode . the impeller 36 is adapted to mulch or chop leaves , grass , and other material vacuumed through the unit to prevent clogging or breaking of the impeller during operation . more specifically , as shown , the impeller 36 comprises a central boss 74 having an axial opening 76 for passage of the motor drive shaft 34 . the impeller 36 further includes vanes 78 radiating from the central boss 74 for effecting centrifugal air flow upon impeller rotation . the impeller is desirably formed from a relatively lightweight and inexpensive plastic material , and is secured for rotation on the drive shaft 34 by a lock washer 80 and a nut 82 . importantly , however , the washer 80 and nut 82 also secure upon the boss 74 a chopping or mulching blade 86 presented toward the air inlet 50 and axially spaced slightly from the vanes 78 . the blade 86 is formed from steel or the like , and has a length spanning at least the diametric width of the air inlet 50 upon rotation with the impeller 36 . in the vacuum mode , the blade 86 functions to chop leaves and other solid vacuumed material to a fine particle size prior to cummunication with the impeller 36 . in this manner , damage to or clogging of the impeller 36 is avoided , and the chopped material is freely blown through the impeller housing 30 to the dust bag 68 . the blower - vacuum unit 10 of this invention is thus quickly and easily changed from a blower mode to a vacuum mode , and vice versa . the unit is relatively lightweight and easily portable , and the rotating components of the unit are unaltered regardless of the mode of operation . a single nozzle tube 64 is conveniently provided with the unit for use as an outlet blower nozzle tube in the blower mode , and as an air inlet vacuum nozzle tube in the vacuum mode . the dust bag 68 is quickly and easily attached to and detached from the unit for easy adjustment of the unit between modes . a wide variety of modification and improvements of the invention disclosed herein are believed to be possible within the skill of the art . for example , the chopping blade 86 may be configured for quick and easy attachment in any suitable manner to the impeller of a conventional portable blower unit to adapt the unit for dual mode operation in either a blower mode or a vacuum mode . accordingly , no limitation on the invention is intended by way of the description herein except as set forth in the appended claims .
a portable blower - vacuum unit has an impeller for drawing air axially through a housing air inlet , and for discharging the air centrifugally through a tangential housing air outlet . in a blower mode , a perforate cover plate prevents ingestion of solid material by the impeller . in a vacuum mode , a vacuum conduit connects to the housing in lieu of the cover plate , and a vacuum bag attaches to the air outlet . a mulching blade rotates with the impeller to chop any solid material passing through the housing when the unit is operated in the vacuum mode .