Abstract:
A standalone portable electric blower has a propeller generating airflow and driven by an electric motor powered: by a power source, said blower including an air-guide conduit made up of a series of three generally cylindrical tubular portions, namely a proximal portion or suction nozzle provided with an air inlet, a distal air exit portion or exhaust nozzle and a central portion. The central portion is a separate piece and is arranged to form a functional assembly, unitary or made up of a plurality of elements and made of a heat conducting material, said central portion comprising the following functional sub-assemblies; an electronic switching electric motor; at least one axial, propeller rotated b the electric motor; air rectifiers; and an electronic board for managing the tool and controlling the motor. The functional assembly is housed in the central or intermediate portion of said air-guide conduit with which said assembly engages,

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       REFERENCE TO AN SUBMITTED ON COMPACT DISC 
       [0004]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    The present invention concerns a standalone portable electric blower with variable air exit speed. It applies in particular to equipment of this type intended tot sweeping and/or cleaning by an blast, of large surfaces such as, for example, lawns, urban streets, outside parking areas, sports or playgrounds, etc. The result obtained by use of such equipment is analog to that obtained by using a traditional broom or rake, but the work is much less fatiguing and incomparably faster. In this application, utilization of such a machine consists of pushing the trash scattered over the ground and lying partly under obstacles such as parked vehicles, to form a heap or window which is then picked up by a suction device, a wad sweeper or a mixer. Such devices are usually found to be in the form of a portable unit which is hand-held and ma be supported by a harness. In practice, they are used while constantly adapting, the airflow speed to the condition of the treated surface. These devices may be designed for professional usage as well as for individual domestic use. 
         [0007]    2. Description of Related. Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
         [0008]    These devices comprise primarily an airflow guiding conduit, featuring a proximal air inlet portion or suction pipe, a distal air outlet part or exhaust pipe and an air blowing device positioned inside the intermediary part of the pipe. This air blowing device ensures the suction of air and its delivery in the form of an airflow characterized by an air output and an air speed at the exhaust of the device. 
         [0009]    The blower or the air blowing device of existing machines is driven by a thermal engine or by a universal electric motor with brushes. It is mostly constituted by a centrifugal turbine. Existing machines operating with a thermal engine are heavy (weights exceeding 4.5 kg in operation), cumbersome, noisy (noise above 100 dB), polluting (using fuel), and generating a significant gyroscopic effect during speed fluctuations considering the variety of rotating parts and their significant inertia due to their weight. Devices using an electric motor are most of the time powered through a power cable from the power grid, or they come in the form of small, battery-powered blowers but with low capacity. Such electric devices are therefore used more for domestic applications, but are not practical for use by professionals working in public spaces or large areas, on account of their small operational range. 
         [0010]    Portable blowers presently available on the market generally use centrifugal turbines. Particular drawbacks of these blowers are:
       Very loud noise (&gt;100 dB generally), obliging the operator to wear hearing protection, and when operating in an urban environment, to limit their daytime use to those hours that are the least annoying for nearby residents;   Significant weight (&gt;4.5 kg) generating additional discomfort for the operator:   Significant space requirements of thermal or electrical motors used to power the centrifugal turbine.       
 
         [0014]    Other noteworthy drawbacks of these motors are due to the fact that:
       They cannot run at high speed (generally the rotational speed is less than 12000 rpm);   Since centrifugal turbines have, by design, a relatively large diameter (of the same size as the dimensions of the motor in general), they present high air speeds on the periphery of the turbine and consequently generate significant ventilating noises;   Since the concept of these devices requires a low cost price, high-performing turbines are not feasible, thus limiting the output of the device and increasing the noise due to the creation of aerodynamic disturbances in the turbine and at its ends;   The assembly of rotating parts has a high moment of inertia which makes rapid modulations of the air output and speed at the blower exit difficult in order to rapidly adapt the operation of the tool to the configuration of the surface to be treated or to the condition of the trash to be swept away (whether dry or wet);   The mass of parts in rotation generates a significant gyroscopic effect which leads to twisted wrists of the operator;   It is very difficult for these devices to reach a weight/power ratio below 5 kg/kW during their operation.       
 
         [0021]    In the U.S. Pat. No. 6,105,206 document an electric and portable air blower is described which is constituted by an elongated support tube the proximal end of which is equipped with a control handle and the distal end of which supports the active components of the device including an electric motor, a fan or compressor and air flow rectifiers. These components are housed in a conduit that is concentrically placed around the distal end of the support tube, this conduit featuring an air inlet and an air outlet. It is expected that said conduit be preferably made of moldable plastic material of a type currently used for molding of various rigid, objects and not of any special plastic material, that is to say of a material with no properties of thermal conductivity. By mourning the control handle and the blowing head of the device at the opposing ends of the support-tube the work is made very difficult and uncomfortable, because of the constant efforts the operator needs to make in order to counteract the tendency of said blower bead to tip downward, in spite of the use of a carrying shoulder strap. Furthermore, the blowing conduit is made of an insulating material which prevents dissipation of the heat generated by the operation of the motor and the fan. 
         [0022]    In the U.S. Pat. No. 4,945,604 document a portable blower is described where the motor, the fan and the air flow rectifiers are installed in the proximal end of a tube which is, on the other hand, equipped with a carrying handle. It is mentioned that the tube is made by an injection-molded process which implies that it is made of plastic material currently used for the molding of various rigid objects and not of a special plastic material, which is to say of a material without properties of thermal conductivity. 
         [0023]    Under these conditions, the proximal portion of the tube in which the active components of the blower are located does not perform any function of dissipating the heat produced by the operation of the motor and the fan. 
         [0024]    The invention aims in particular at making available to users a portable electric blower that is quiet, lightweight, well balanced, without effects of inertia or gyroscopic effects running counter to holding the device while in operation and eliminating the effects of discomfort while using such tools, not to mention the risks of trauma over time to the operators&#39; wrists. It must be taken into consideration that sometimes the tool is carried by the operator for several hours, with the result that this tool which is supposed to make work easier for the operator, can cause more severe muscular pain than the use of a rake, if the tool weighs too much. 
         [0025]    Another aim of the invention is the embodiment of a portable electric blower with low-noise operation, of simple construction, featuring means for quick modulation of the air flow exiting from the device, this air flow being directed and structured. 
       BRIEF SUMMARY OF THE INVENTION 
       [0026]    According to the invention, this objective is achieved by a standalone portable electric blower featuring at least one axial propeller generating an air flow and driven by an electric motor powered by a current source, said blower comprising an air-guide conduit consisting of a succession of three tubular parts of a generally cylindrical shape, namely a proximal part or suction nozzle with an air inlet, a distal air outlet part or exhaust pipe and a central or intermediary part characterized in that the central part is a separate piece and is fitted so as to constitute a functional assembly, solid bloc or consisting of an assembly of a number of elements and made of a material that is a good heat conductor, said assembly featuring the following functional sub-assemblies:
       an electric motor with electronic switching;   at least one axial propeller driven in rotation by the electric motor;   air flow rectifiers;   an electronic board for managing the tool and the motor controls, said functional assembly being housed in the central or intermediary pan of said air-guide conduit with which it is in contact.       
 
         [0031]    According to an advantageous characteristic arrangement, the functional assembly features also the following functional sub-assemblies;
       an aerodynamic air inlet cone positioned coaxially upstream of the propeller; and/or   an aerodynamic cone air outlet cone positioned coaxially downstream of the electric motor.       
 
         [0034]    According to a preferred implementation, the central functional assembly includes also a passageway housing the electrical cable(s) of the motor connecting the electronic board and the electric motor. 
         [0035]    It is clear that a major advantage of the invention is to bring together all elements necessary for the functions of the tool in its central pan. This arrangement makes it possible in particular to achieve three functions: the function of mechanical support for all the elements required for the functions of the tool; the function of rectifier of the air flow generated by the propeller; the function of heat exchanger enabling good dissipation of the heat generated b the motor and the electronic board and it makes it easy to perform functional tests prior to the complete assembly of the device. 
         [0036]    According to an interesting implementation, said suction nozzle presents, upstream of the axial fan, an elbow the proximal end of which, demarcating the air inlet, is directed downward, considering a working position of the blower according to which the blower is directed forward and the operating handle of the blower is placed on top of the blower. 
         [0037]    According to an advantageous implementation, the operating handle of the blower is placed above the central part fitted to constitute the functional assembly, preferably positioned above the center of gravity (G) of the device, considering a working position of the blower according to which the blower is directed forward. 
         [0038]    The operating handle also incorporates the control elements of the device, namely a trigger, a secondary electronic board for analyzing the position of said trigger, as well as an air speed selector and a device for displaying this speed managed by said secondary electronic board so that the position of said trigger can define, an air speed proportional to the maximum speed set by the selector, in connection with the management control board of the tool and of motor guidance. It also includes the link with the electric power cable connected to a battery. This cable is provided, at its end, with the removable connector plug to the battery pack carried by the operator Or with an exterior power source, and may incorporate, furthermore, a quick connect/disconnect plug of the tool so that the operator can quickly free the tool from its connection with the battery. 
         [0039]    According to an advantageous implementation, the control handle is made of two half shells capable, once they are assembled, of providing a rapid fastening of all the elements of the tool to each other, but also to ensure the definitive design form of the tool. It will be completed by a housing that is adapted as well to the shell of the tool and to covering the electronic board in order to protect it, but also to provide for its inspection for maintenance purposes, if necessary, without taking the whole tool apart. 
         [0040]    Besides the qualities sought after and obtained by the portable electric blower featuring the aforementioned characteristics, the blower has also these advantages:
       very reduced space requirement of the tool around the air-guide conduit;   reduced weight (2.6 kg);   considerably less noise (&lt;9 dB);   high rotational speed of the axial propeller (&gt;20000 rpm) favoring its output in order to prolong the duration of utilization for one battery charge;   a very low Weight/Power proportion (3.5 kg/kW);   simplicity of assembly of its various components;   reliable operation of the device over several hours of daily use:   power of a device of such a design can easily reach 2 kW.       
 
         [0049]    In other areas of application, such as aeromodelling, building ventilation, cooling of electronic systems, spraying, or even air supply in mine galleries, one is familiar with devices designed for generating air flows by use of axial fans such as the US-2006/0.237.168 patent which describes a ventilation device comprising:
       a housing or casing;   a fan consisting of blades driven in rotation by a motor and placed in said housing; and,   a number of guide vanes fixed inside said housing, said guide vanes being thermally coupled to an electronic component through the intermediary of a beat pipe, so that the heat generated by the electronic component is transferred, through said guide vanes, in an air flow generated by the rotation of a number of fan blades.       
 
         [0053]    According to this document, the blowing device is constituted by the assembly of several pans, namely: the exterior housing, the housing of the fan motor, the guide vanes of the air flow and the support of the electronic component. In particular, the electronic component is connected to the guide vanes through the intemedially of other components of the heat pipe or heat conductor type. This results in a low level of removal of the heat generated by the fan motor and the electronic component. 
         [0054]    Devices of this kind are, in practice, intended for cooling of electronic components as described in the US-2006/0.237.169 patent, where the cooling functions predominate over the generation of a significant air flow which is better suitable for blowing. These devices function also in a fixed manner with a low power supply (less than 100 W in general), but in a continual manner with little no need for modulating the air flows and speeds. 
         [0055]    One also finds much more powerful fans of this type (sometimes several tens of kW), especially for the ventilation of mines such as described in the document FR-2.603.350, but these are fixed, heavy systems which are always powered over the grid and where the outer and inner housings and the radial vanes connecting said housings are constituted by several assembled parts during the assembly of the fan, which, in addition to the drawback mentioned above, has an unfavorable influence of the cost of the equipment. 
         [0056]    According to another significant objective, the invention aims at providing, a lightweight and compact air blowing device that is high-performing, of simple and economical construction, generating low inertia and a quasi-non-existent gyroscopic effect, an air flow drawn at high speed with excellent ventilating output so as to considerably increase the range of a device powered by a battery, for example a Lithium-ton or a Lithium-Polymer battery of high capacity, and without no cooling, device other than the components strictly necessary for the generation of the air flow. 
         [0057]    The second objective cited above is achieved by means of an air blowing device which is particularly remarkable in that it comprises, on the one hand, an exterior housing of a general, cylindrical shape, an interior, cylindrical housing of a smaller diameter and positioned axially in said exterior housing, said exterior and interior housings being connected by radial blades capable of rectifying the air flow of the propeller, currently called rectifiers, demarcating a number of cooling air circulation channels positioned between said housings and extending in parallel to the axis of the latter and, on the other hand, an axial fan the propeller of which is driven in rotation by an electric motor housed in the interior housing, this device being particularly remarkable in that the exterior housing, the interior housing and the rectifiers connecting said housings are made of a single piece of as good heat-conducting material, for example of aluminum another metal, of a composite material or a plastic material with good thermal conductivity qualities. 
         [0058]    According to a very advantageous implementation, the exterior housing is provided with a plate that is in contact with said exterior housing and on which an electronic board is fastened for ensuring the management of the operation of a portable electric blower or analog equipment which includes such a device. 
         [0059]    According to another significant characteristic arrangement, this holding plate of the electronic board is made of a single piece with the assembly constituted by the exterior housing, the interior housing and the rectifiers. 
         [0060]    According to another advantageous characteristic arrangement, the blades of the axial propeller and the rectifying ribs are curbed in the opposite direction. 
         [0061]    According to an interesting implementation, the rectifiers and the air circulation channels have a length corresponding essentially to the length of the interior housing which encloses the motor of the axial fan. 
         [0062]    According to another interesting implementation the solid bloc assembly constituted by the exterior housing, the interior housing, the rectifiers and the plate holding the electronic board, is made of magnesium. 
         [0063]    The assembly constituted by the exterior housing, the interior housing, the rectifiers and the plate holding the electronic board is obtained, in a single piece, by a molding process or by a precision injection process. 
         [0064]    Besides the fact that it does indeed possess the previously indicated sought after qualities, the claimed air blowing device has further advantages such as sturdiness, so one can expect long-lasting operation, ease of performing operational tests during its assembly, maintenance or repair, a smaller number of constituent parts and a reduced space requirement. The rectifiers connecting the exterior housing to the interior housing allow for rectifying the air flow while enabling a transfer of the heat stored b the interior housing enclosing the motor of the axial fan, and also ensuring circulation of cooling air around said interior housing so as to create optimal thermal equilibrium of the assembly due to the significant air speed generated by the propeller. 
         [0065]    On the other band, a portion of the heat produced by the electronic board is transferred to the exterior housing, even to the rectifiers, by way of the plate supporting said electronic board whereby the cooling of the latter is ensured. 
         [0066]    It is to be noted here that the task of cooling the components of the equipment does not use other parts than those serving the main function of the tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0067]    The above-mentioned aims, characteristics and advantages and still more, will become clearer in the description which follows and the attached drawings in which: 
           [0068]      FIG. 1  showing a portable electric blower held by an operator and powered by a battery carried on the back of the latter, through an electric cord. 
           [0069]      FIG. 2  is an exterior view and at a larger scale of the blower. 
           [0070]      FIG. 3  is an exploded perspective view of the portable electric blower. 
           [0071]      FIG. 4  is a detailed exploded view in perspective with partial sections of the air blowing device housed in the central part of the blower. 
           [0072]      FIG. 5  is a detailed rear view, in perspective and at larger scale, illustrating the solid bloc assembly shown without the axial fan. 
           [0073]      FIG. 6  is a front view and at a larger scale of the propeller of this axial fan. 
           [0074]      FIG. 7  is a perspective view of an example of implementation of an air blower device according to the invention. 
           [0075]      FIG. 8  is an axial section view of this device. 
       
    
    
       [0076]    Reference to said drawings is made to describe interesting, although by no means limiting examples of implementation of the air blowing device and of a portable electric, blower applying it. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0077]    The blower shown comprises primarily an air guiding conduit  1  constituted by a succession of three tubular parts of generally cylindrical shape, namely a proximal part or suction nozzle  2  provided with an air inlet  3 , a distal air outlet part or exhaust pipe  4  and a central or intermediary part  5  is a separate piece positioned between said proximal and distal parts. In this central part is housed a functional assembly designated. globally by reference  6 , solid bloc or formed of an assembly of a number of elements and made of a material that is a good heat conductor, said assembly features the following functional sub-assemblies:
       an electric motor with electronic switching  7 , commonly called a brushless motor;   at least one axial propeller  8  driven in rotation by the electric motor;   air rectifiers  9 ;   an electronic board  10  for tool management and motor control.   said functional assembly being housed in the central or intermediary part of said air-guide conduit with which it is in contact.       
 
         [0083]    Advantageously the functional assembly features also the following functional sub-assemblies:
       an aerodynamic air inlet cone  11  placed coaxially upstream of the propeller; and/or   an aerodynamic air outlet cone  12  placed coaxially downstream of the electric motor, and ensuring the prevention of the appearance of turbulences in the air flow.       
 
         [0086]    Preferably, the functional central assembly  6  comprises a passageway  13  situated primarily in the air current and housing the electric cable(s)  14  connecting the electronic board  10  and the electric motor  7 , in order to ensure the protection of this or of these cables. This passageway may be constituted by a specific sheath or may be made in one of the rectifiers  9 , or in a rib provided for this purpose. 
         [0087]    According to an interesting implementation, said suction nozzle  2  presents, upstream of the functional assembly  6 , an elbow  22  the proximal end of which demarcates the air inlet  3 , is oriented downward, considering a working position of the blower according to which the blower is directed forward and the control handle  15  of the blower is placed on top of it. 
         [0088]    According to an advantageous implementation, the control handle  15  of the blower is placed above the central part enclosing the functional assembly  6 , considering a working position of the blower according to which it is directed forward ( FIG. 1 ) and positioned essentially above the center of gravity G. 
         [0089]    According to one implementation, the handle  15  is constituted by the assembly of two half shells  30  and  31 , and it incorporates the control actuators of the tool, featuring in particular a secondary electronic board  32 , connected to the electronic management board of the tool and of the motor control  10 . This secondary electronic board  32  is configured to analyze the position of the trigger  34  controlling the operation and stopping of the tool, in order to modulate the air speed at the outlet of the device proportionally to the position of said trigger; the objective being to obtain a progressive and precise dosage of the air flow. 
         [0090]    The system for measuring the position of the trigger  34  uses a directed field magnet attached to said trigger (mobile part) associated with a magneto-resistive sensor placed on the secondary electronic board  32  (fixed part). Concerning the disclosure of such a system, one needs to refer to the description and drawings of the French patent published under number 2.935.175. 
         [0091]    To complete the modulation of the air exiting from the device, the secondary electronic board  32  features a speed selector and a display device of the speed selected, limiting the maximal speed of the air exiting from the device at the selected setting, the objective being to assist the operator in reducing the power consumption by adapting the best possible speed range available. The different modes or speed ranges selected offset the high limit of frequency of the motor (for example, speed range 1 corresponds to a frequency between  0  and 15,400 rpm, speed range 4 corresponds to a frequency between 0 and 21,300 rpm). The change of speed is made by impulse on the appropriate selection button. A Hall-effect sensor that is also present on the secondary electronic board  32  (fixed part) functions here in “all or nothing” mode, which is to say in non-progressive mode. It thus detects a distancing or approaching of the magnetic field of the magnet attached to the button or other control element (mobile part) of this selector. Information processing of the detected signal makes it also possible to determine if the button is pushed briefly or held, and, if applicable, a fifth speed range is engaged with this prolonged push of the button in order to deliver more power. 
         [0092]    The two half shells ( 30  and  31 ) constituting the handle  15  are, incidentally, capable, once they are assembled, of enabling a quick lastening of the totality of the tool elements to each other (proximal part  2 , central part  5 , and distal part  4 ) and also of ensuring the definitive specific form of the tool. Closure of the shell is completed by a housing  35  adapted to the shape of the tool and covering the electronic board  10  in order to protect it and enabling also its inspection for maintenance, if necessary, without having to disassemble the entire tool. 
         [0093]    According to one implementation, the portable electric blower configured in the manner disclosed above may be equipped with a ring or other fastening element so it can be suspended from a harness H worn by the operator. 
         [0094]    On the other hand, the electric motor  7  may be powered either by a battery B inserted into the blower, or through the intermediary of an electric cable  16  provided with a connecting means to a current source (power outlet of the power adapter or battery carried by the operator). 
         [0095]    According to another significant characteristic arrangement, the functional assembly  6  housed in the central part  5  comprises an exterior housing  17  of a general cylindrical shape, an interior cylindrical housing  8  of a smaller diameter d and positioned axially in said exterior housing, said exterior housing  17  and interior housing  18  being linked by radial ribs commonly called rectifiers  9 . These rectifiers demarcate a number of cooling air circulation channels  19  arranged between the exterior housing  17  and the interior housing  18  and around the latter. They extend longitudinally between said exterior housing  17  and interior housing  18 . 
         [0096]    The exterior housing  17  presents open proximal and distal ends constituting respectively an air inlet  17   a  and an air outlet  17   b.    
         [0097]    The assembly constituted by the exterior housing  17 , the interior housing  18  and the rectifiers  9  is made of a single piece in a material that is a good heat conductor, for instance of magnesium or of aluminum, or even of composite or plastic matters possessing this property. This solid bloc assembly can be obtained by a molding process or by a precision injection process known as such. 
         [0098]    The functional assembly  6  housed in the central part  5  is in contact with the inner wall of the latter. 
         [0099]    In this assembly is housed an axial fan  20 , consisting of the propeller  8  and the motor  7 , the propeller  8  of it being, positioned in the proximal part of the exterior housing  17  and the electric motor  7  which provides rotation of said propeller is enclosed in the interior housing  18  which presents a length shorter than that of the exterior housing  17 . 
         [0100]    The propeller  8  has a diameter D which is barely smaller than the internal diameter of the inlet  17   a  of the exterior housing  17  in which the propeller is housed, so as to be able to rotate inside the latter without any friction. 
         [0101]    The rectifiers  9  and the air circulation channels  19  demarcated by these rectifiers may have a length corresponding essentially to the length of the housing  18  enclosing the electric motor  7  of the axial fan  20 . They could however present a shorter length than that of the interior housing  18 , for example, they could have a length equal to the length of the blade chord  8 a of the propeller  8 . 
         [0102]    Besides, the functional assembly  6  comprises an aerodynamic air inlet cone  11  positioned coaxially upstream of the propeller  8 , and/or an aerodynamic air outlet cone  12  positioned coaxially downstream of the electric motor  7 , in the extension of the interior housing  18 . The length of the aerodynamic air outlet cone  12  is clearly greater than that of the aerodynamic air inlet cone  11 . For example, it presents a length greater than its diameter. 
         [0103]    Advantageously the blades  8 a of the axial propeller  8  and the rectifiers  9  are curved in the opposite direction which results in a good aeraulic output. 
         [0104]    The interior housing  18  in which the electric motor  7  of the axial fan  20  is housed, is positioned downstream of the propeller consisting of the assembly of blades  8 a, considering the direction of displacement of the air flow generated by said fan. On the other hand, said propeller  8  presents a diameter D larger than the diameter d of the interior housing  18 . 
         [0105]    The rectifiers  9  allow rectifying the air flow drawn upstream of the axial fan  20  and provide the transfer of a portion of the heat stored by the interior housing  18 enclosing the electric motor  7 , from the axial fan  20  toward the exterior housing. The air flow produced by the axial fan  20  participates efficiently in the cooling of the walls of the exterior cylinder  17 , of the interior cylinder  18  and of the radial rectifying ribs of said air flow, with which walls the latter is in contact. 
         [0106]    The air blowing device featuring the characteristics described above makes it possible to obtain an air flow at the outlet of the tool with significant speed and volume, by means of a motor capable of providing a rotating speed above  20 , 000  rpm. 
         [0107]    Production of this assembly in a single piece assures its proper balance through conduction and thermal radiation in the air flow generated by the propeller  8  of the fan  20 , its method of production also makes it possible to obtain a surface condition that limits losses of pressure of the air flow crossing it. 
         [0108]    The single bloc assembly  17 - 18 - 9  is machined to ensure ideal centering of the constitutive parts of the axial fan  20  so as to reduce the play of the propeller at the end of blades in order to increase aerodynamic performance and to reduce noise. 
         [0109]    According to another advantageous characteristic arrangement, the exterior cylindrical housing  17  is equipped, on its outside, with a plate or base  21  on which is attached an electronic board  10  which is configured to provide management or guidance of the motor of the air blowing device of a portable electric blower or analog equipment, including the claimed air blowing device. This electronic control of the motor ensures its optimum operation under all of its operating conditions (continuous or transient), via control elements (trigger, power limiter). 
         [0110]    The electronic board enables changes of power settings, that is to say to modulate the air speed at the tool outlet, more or less frequently, in order to adapt them to the configuration of the treated surface, particularly when the areas to be treated are hard to reach (this is for example the case of surfaces underneath vehicles parked on urban streets), or to the conditions of the leaves (dry or wet) or other trash to be swept away. 
         [0111]    According to another significant characteristic arrangement, the plate  21  holding the electronic board  10  is made of a single piece with the assembly constituted by the exterior housing  17 , the interior housing  18  and the rectifiers  9 . 
         [0112]    The fastening of the electronic  10  on a support or plate  21  that is integral with the exterior housing  17  allows for good dissipation of the heat generated by said electronic board. 
         [0113]    It is noted that according to the invention, all elements necessary for the functions of the tool are brought together in its central part. 
         [0114]    This provides several interesting advantages, in particular it contributes to proper balancing of the blower, facilitates easy assembly and maintenance, and the possibility to easily perform operational tests on said central part, prior to the complete and definitive assembly of the equipment.