Propeller of a pulsed airflow generator, in particular for a portable blower

Abstract

A propeller of a pulsed airflow generator, in particular for a standalone portable blower, of the type made up of the assembly of two parts coaxially adjoining one another, i.e.: a first front part made as a single piece and comprising a plurality of twisted blades connected to a central ring, and a second rear part with a generally conical shape also made as a single piece, the central portion of said assembly having a conical shape and making up the rear portion of an air-inlet cone, said propeller being characterised in that said first and second rear parts are secured by a clamping device made up of a hub including two parts assembled coaxially and between which said two parts that make up the propeller are clamped, said hub being rotatably secured to the latter and maintaining said front and rear parts in the assembled position thereof.

Claims

1. A propeller assembly for a pulsed airflow generator, the propeller assembly comprising: a propeller having: a front piece formed by a single block and having a number of twisted blades attached to a central ring; and a rear piece formed by another single block and having a generally conical shape, said rear piece being rigidly and coaxially attached to said front piece, said front piece said rear piece forming a central part having a conical shape and defining a rear portion of an air inlet cone; a clamping device having: a hub having a pair of coaxially assembled pieces, said hub having an axial bore adapted to seat a shaft or a drive motor therein; wherein said front piece and said rear piece are clamped between the pair of coaxially assembled pieces so as to assure that said front piece and said rear piece remain in an assembled position, said hub being integral in rotation with said front piece and said rear piece.

2. The propeller assembly of claim 1, wherein a front piece of said pair of coaxially assembled pieces has a conical shape and defines a vertex of said air inlet cone.

3. The propeller assembly of claim 1, wherein said pair of coaxially assembled pieces are fitted together.

4. The propeller assembly of claim 3, wherein said pair of coaxially assembled pieces are forced fitted together.

5. The propeller assembly of claim 1, said number of twisted blades being attached to said central ring through respective blade roots, said rear piece having a plurality of spaced claws respectively engaged in gaps between adjacent blade roots.

6. The propeller assembly of claim 5, the blade roots having a surface which overlaps on one side of the blade with an outer surface of an overlapping part of the blade roots, said claws having an outer surface that constitutes portions of said air inlet cone.

7. The propeller assembly of claim 1, said front piece and said rear piece being molded.

8. The propeller assembly of claim 1, said front piece and said rear piece being formed of a rigid plastic material.

9. The propeller assembly of claim 1, said front piece and said rear piece being formed of a metallic material.

10. A portable blower comprising: the propeller assembly of claim 1, and said shaft or drive motor.

11. The portable blower of claim 10, including both said shaft and said drive motor, said drive motor having said shaft , said shaft having an end that is force fitted to a front piece of said pair of coaxially assembled pieces, said hub having an axial bore seated on said end of said shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above aims, characteristics and advantages, as well as still more, will become clearer from the following detailed description and the attached drawings in which:

(2) FIG. 1 is a perspective view of an example of an axial propeller produced according to the invention.

(3) FIG. 2 is an exploded view of the two constitutive parts of the propeller the assembly hub of which is not shown.

(4) FIG. 3 is also a perspective view of the two constitutive parts of the propeller seen from another angle.

(5) FIG. 4 is an exploded view of the assembly hub.

(6) FIG. 5 is an axial section of this hub shown in assembled position.

(7) FIG. 6 is a partial axial section showing the two constitutive parts assembled by the hub and of the drive shaft.

(8) FIG. 7 is a cross section of the central part of the propeller and shows the drive mechanism in rotation.

(9) FIGS. 8, 8A, and 8B illustrate an application of the principle of the triangle of speeds.

(10) FIG. 8 is a schematic plan view of a propeller with twisted blades.

(11) FIG. 8A is a section view along line A-A of FIG. 8.

(12) FIG. 8B is a section view along line B-B of FIG. 8.

(13) Reference is made to these drawings to describe an interesting, although by no means limiting example, of embodiment of the propeller according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(14) The axial high-performance propeller 1 according to the invention is constituted by the assembly of two parts coaxially attached one after another, like this: a first front part 2 formed of a single block and constituted by a number of twisted blades 3 attached to a central ring 4, and a second rear part 5 of a general conical shape also formed by a single block, the central part 6 of this assembly presenting a continuous conical shape or more exactly the form of a truncated cone constituting the rear part of an air inlet cone.

(15) Advantageously, the front part 2 and the rear part 5, are assembled by rigidly fitting them together.

(16) According to an interesting implementation, the twisted blades 3 are attached to the central ring 4 through the intermediary of spaced blade roots 3a and the rear part 5 features a number of spaced teeth or claws 5a engaged in the gaps 7 provided between said blade roots 3a.

(17) The claws 5a of the rear part present a straight edge oriented along a generating line of the air inlet cone or oriented obliquely in relation to this generating line, and an opposite curved edge the shape of which corresponds to the surface of the blade roots this curbed edge comes into contact with. This complementary shaping of the claws 5a and the blade roots 3a ensures good assembly by fitting together the front part 2 and the rear part 5.

(18) The blade roots 3a to which the base of blades 3 is attached present, laterally, a surface that overlaps one of the sides of said base. The outer surface 8 of the overlapping part of the blade roots 3a and the outer surface 9 of the teeth or claws 5a constitute portions of the surface of the air inlet cone 6.

(19) Preferably, the front part 2 and the rear part 5 are obtained by molding, using any suitable equipment or process, for instance by an injection process that is known per se.

(20) Advantageously the front piece 2 and the rear piece 5 are made of plastic or light metal, presenting the desirable rigidity for their function.

(21) According to the invention, maintenance of the front piece 2 and the rear piece 5 in the assembled position is achieved, by a clamping device 10 (FIGS. 4 and 5) constituted by a hub comprising two pieces 11 and 12 that are coaxially assembled and between which the two fitted parts 2, 5 constitutive parts of propeller 1, are clamped.

(22) The hub 10 is integral in rotation with the propeller 1. For example, the inner cylindrical surface of the central ring 4 presents, for this purpose, angularly spaced ribs 13 that are oriented in parallel to its axis, whereas the outer cylindrical surface of the rear piece 10 of hub 9 features angularly spaced grooves 14 into which the ribs 13 are engaged.

(23) According to the illustrated example, the front piece 12 of the clamping hub 10 presents a front portion 12a of conical shape positioned in front of the cone 6 and constituting with the latter an air inlet cone 6-12a. Said. front portion 12a constitutes the vertex of this air inlet cone.

(24) Locking of the two pieces 11, 12 of the clamping hub 10 in the clamping position is preferably obtained by a forced fitting of the rear piece 11 of said hub 10 into the front piece 12 of the latter.

(25) The hub 10 features an axial bore 15 for seating the end 16a of the shaft of a drive motor 16, the shaft end being made integral with the front piece 12 of the hub 10 through forced fitting.

(26) It is clear that the shaft 116 is thereby integral in rotation with the hub 10 which is itself integral in rotation with the actual propeller 1.

(27) The portable blower according to the invention is of the type that includes an axial fan.

(28) According to the invention, this blower is remarkable in that the axial fan presents the major characteristic arrangements described above, or that it results from the implementation of the process according to the invention.