WO1991012901A2

WO1991012901A2 - Electromechanical vibration generator and device using it

Info

Publication number: WO1991012901A2
Application number: PCT/FR1991/000178
Authority: WO
Inventors: Christian Houze; Serge Legrand
Original assignee: Procedes Techniques De Construction
Priority date: 1990-03-02
Filing date: 1991-03-01
Publication date: 1991-09-05
Also published as: FR2659033B1; EP0471059A1; JPH04505696A; FR2659033A1; WO1991012901A3

Abstract

The vibration generator described comprises a body (3) made at least partially from a magnetisable material and able to move along at least one guide element (6) such that its centre of gravity (O') can move along a curved path about a central axis of rotation (O), and electromagnetic means for generating a rotating magnetic field capable of driving the said body (3) along the guide elements (6). This structure eliminates all mechanical transmission and also reduces friction to a minimum.

Description

ELECTROMECHANICAL VIBRATION GENERATOR AND DEVICE

USING THIS GENERATOR.

The present invention relates to an electromechanical vibration generator which can be used in particular, but not exclusively; in the vibrating needles used to ensure the vibration of the concrete.

It is known that the electromechanical generators used at present involve weights excen¬ trated relative to a rotary drive shaft, driven in rotation by a motor. These weights, when rotating, cause an imbalance capable of generating vibrations.

In the generators used for the vibrating needles which serve to ensure the vibration of the concrete, the drive of the rotary shaft is ensured by an electric motor engaged with the shaft, either directly, by means of a gearbox, or even via a flexible cable transmission.

In all cases, the high rotational speeds of the counterweights which make it possible to obtain the desired vibration frequencies, generate intense centrifugal forces and, consequently, significant stresses, both at the pivoting level and at the level of the transmission means used.

It is therefore necessary, for a longer service life, to use components with high mechanical resistance and, in particular, in many cases, to mount the rotary shaft carrying the eccentrics on two special bearings (so thus reducing the load per bearing).

It therefore appears that if the vibration generators produced at the present time are effective, they nevertheless present the drawback of being relatively complex, both in terms of the technique used and of their method of manufacture. They are, therefore ,. of a relatively high cost price.

In order to eliminate this drawback, the invention provides a vibration generator of the type comprising a body at least partially made of a magnetizable material and movable along at least one guide element so that its center of gravity can move along a closed curved path, and electromagnetic means for generating a rotating magnetic field capable of driving said body along the guide elements.

According to the invention, this generator is characterized in that:

- the electromagnetic means consist of a central core,

said body has a hollow shape surrounding said core and subjected to the rotating magnetic field produced by the latter,

- Said guide means comprise a guide track on which is supported, at all times, a generator different from an annular zone of the over- internal face of said body, when said body is driven by said magnetic field.

It appears that, thanks to the structure described above, the means ensuring the vibrations and the motor means form a single entity excluding any mechanical transmission system and any pivoting.

In addition, the friction between the elements is almost zero, because the guides are provided by successive presses along the guide track and, as a result, friction forces are avoided.

The stator winding can be performed on a central core having polar blooming sailants.

According to a first exemplary embodiment, the excen¬ trated core constituting the rotor forms a crown suspended by its internal bore on the stator formed by the cen¬ tral core, by means of a cylindrical sheath of thickness equal to an air gap to respect.

According to a second embodiment, the eccentric core constituting the rotor forms a crown, an external wall of which rolls over the internal bore of the envelope constituting the concentric raceway, the internal diameter of the crown being such that it allows a suitable air gap to exist between the outer wall of the central core or stator and the bore of the crown constituting the eccentric core.

This solution makes it unnecessary to use a sheath to create the air gap.

In the case of the production of a generator having a small diameter, the stator may include two series of inductors arranged at each end of the housing.

According to a variant of this latter embodiment, the stator consists of two series of inductors arranged at each end of its central core.

Other characteristics will appear during the description which follows with reference to the appended drawings in which:

Figures la and lb are diagram¬ tick views, respectively in cross section and in axial section of a first embodiment of a generator according to the invention;

Figure 2 is a schematic cross-sectional view of an alternative embodiment of the generator according to Figure 1, wherein the rotor is provided with a plurality of permanent magnets;

Figure 3 is a schematic cross-sectional view of a second embodiment of the generator according to the invention;

Figure 4 is a schematic cross-sectional view, corresponding to that of Figure 2 but in which the permanent magnets are replaced by axial cavities;

Figures 5 and 6 are schematic cross-sectional views of vibration generators in which the rotors follow oval paths so as to favor

The amplitude of the vibrations along a determined axis; FIG. 7 is a schematic view of a unidirectional vibrator produced by the association of several generators of the type of those represented in FIGS. 5 and 6;

Figure 8 is a schematic axial section of a vibration generator capable of generating an adjustable torque.

In the example shown in FIGS. 1a and 1b, the vibration generator comprises:

- A cylindrical casing 1, with a longitudinal central axis O;

- A cylindrical stator 2 disposed inside the casing 1, coaxial with the latter;

an annular rotor 3 mounted freely in the intermediate space between the casing 1 and the stator 2, and

- A sheath 4 of a non-magnetic material, preferably insulating, which has a thickness equal to an air gap "e" and which at least partially covers the stator 2.

More precisely, the rotor 3, made of magnetizable material, is dimensioned so as to be able to roll freely by its internal cylindrical surface 5 on the external cylindrical surface 6 of the sleeve 4, and this, without its external cylindrical surface being able come to bear on the inner cylindrical surface of the casing 1. The rotor 3 can therefore perform a rotary movement during which its axis 0 ′ sweeps a cylindrical surface centered on the axis 0.

Of course, the radius r of this cylindrical surface (which in fact constitutes the eccentricity of the rotor 3) is defined as a function of the inertial characteristics to be obtained. The stator 2 has a structure substantially similar to that of a wound rotor of an asynchronous machine. It is produced for example using a stack of discs made of silicone sheet provided with a plurality of notches T_ to T4 delimiting between them polar expansions N, S around which are wound windings, not shown .

The excitation of the windings is carried out in sequence so as to generate a rotating magnetic field, the pole shoes having alternating North (N) and South (S) polarities.

Under the effect of this rotating field, the rotor 3, attracted by the successive pairs of poles N, S, is caused to roll on the stator 2 by its inner cylindrical face 5 and therefore performs a rotational movement "to catch up with the field "for example in the counterclockwise direction of FIG. 1, the axis 0 'sweeping a cylindrical surface of axis O by producing the same vibratory effect as that which would be produced by a counterweight centered at 0'.

As previously mentioned, the sleeve 4, which here extends over the entire length of the stator 2, serves both as a raceway for the rotor 3 as well as for the réali¬ tion of the air gap.

These two functions could be ensured by two non-magnetic rings 40, 40 'surrounding only the ends of the stator 2 and having a thickness cor¬ corresponding to the value of the desired air gap, or by two discs 8, 9 (in dashed lines) of non-magnetic material arranged at the two ends of the stator 2, coaxially with the latter and having a radius equal to the sum of the radius of the stator 2 and of a value corresponding to the desired air gap "e", the cylindrical surface of these discs 8, 9 then serving as a raceway for the rotor 3.

The variant embodiment shown in FIG. 2 essentially differs from the previous one in that the bore 3a of the eccentric core 3 in the form of a crown and constituting a part activated by the rotating field, is equipped with a plurality of 'permanent magnets A, B, C, D, E, F arranged radially and equidistantly at a pitch identical to that of the windings (not shown) of the poles N, S of the stator 2. The movement of the said magnets in operation is represented fictitiously by the positions A ', B', C ', D', E ', F' given by way of illustration.

The embodiment represented in FIG. 3 differs essentially from that of FIG. 1 in that the eccentric core constituting the rotor forms a crown 3 whose external wall 3b rolls on the internal bore 1a of the envelope 1 thus constituting the concentric raceway following contact by an internal generator of the latter on an external generator of said crown 3 (the internal diameter "D" of the crown 3 being equal, for a given point, to the distance "d "from a point P of the bore 3a of the crown 3 to a diametrically opposite point P 'situated on the external wall 2a of the stator 2, plus the air gap distance" e ").

Furthermore, it should be noted that in the example shown in FIG. 2, the permanent magnets A to F and G to J, respectively included in the eccentric core 3 in the form of a crown can be replaced by axial recesses respectively 31 to 35 occupying substantially the same place and which make it possible to create similar polarities (FIG. 4).

In the examples described above, the rotors are guided by circular surfaces, so that their centers of gravity themselves make circular paths.

Of course, the invention is not limited to such a feature. On the contrary, it proposes to take advantage of the specific structure of the generators described above in order to obtain, with simple shape modifications, an oval trajectory of the rotor and, consequently, vibrations having maximum amplitudes along an axis. privileged.

This result can be obtained for example:

- using a structure of the type of that of the generator shown in FIG. 3, but in which the annular rotor, of cylindrical shape, rolls on the oval section bore of the envelope, surrounding the central stator 2 which has itself an oval shape (Figure 5); - Using a structure of the type shown in Figure 1, but in which the annular rotor 3 which is guided by its inner surface on a central stator 2, of cylindrical shape, has an oval section (Figure 6).

Advantageously, the generators described above can be used to produce apparatuses for generating unidirectional vibrations using one or more pairs of generators, for example two pairs as shown in FIG. 7.

In this example, the generator involves two pairs of structures of the type shown in FIG. 5, the central cores 40 to 43, integral with each other, are oriented parallel to each other and are oriented in the same direction. The two structures Si, S2 - S3, S4 of the same pair present:

- rotors 44, 45 - 46, 47 rotating, synchronously, in the same direction which is opposite to the direction of rotation of the rotors of the other pair,

- the same plane of symmetry Pi, P'l - P2, P'2 passing through the major axes of their central cores 40, 41 - 42, 43,

- two respective parallel planes of symmetry P3, P'3 - P4, P'4 passing through the minor axes of their central cores 40, 41 - 42, 43, these two planes being coincident with the corresponding planes of symmetry of the structures of l 'other pair.

According to this arrangement, the longitudinal axes of the cores 42, 43 - 40, 41 form the edges of a prismatic volume of square section.

It is clear that when the rotors 44, 45 - 46, 47 of these structures perform their rotational movements, the forces generated parallel to the small axes of the central cores will compensate (resulting zero), while the forces generated parallel to the large axes will accumulate, so that a unidirectional vibrator is thus obtained which is parallel to the major axes of the cores and generates vibrations of maximum amplitude.

Of course, it would be possible to generate, parallel to the minor axes of the cores, vibrations of smaller amplitude by rotating the rotors 47 and 44 in the same direction and the rotors 46 and 45 in the opposite direction.

The amplitude of the vibrations generated by the previously described apparatus could also be adjusted by varying the orientation of the central cores 41 to 44, with respect to each other. In the embodiment shown in FIG. 8, the rotor 50 which has the shape of a tubular section rolls by its two chamfered ends 51, 52 on two respective frustoconical raceways 53, 54, coaxial 1 to 1 other and movable one with respect to the other.

This structure allows adjustment of the eccentricity of the rotor 50 and therefore of the amplitude of the vibrations generated, by a simple adjustment of the spacing of the two frustoconical raceways 53, 54.

Such adjustment of the amplitude of the vibrations could also be obtained by means of a generator of the type shown in FIG. 7, involving at least a pair of structures Si, S2 or S3, S4.

In this case, the controlled variation of the amplitude of the vibrations is ensured by generating a phase shift in the excitation cycles of the windings of the cen¬ traux cores 40, 41 or 42, 43, thanks to an appropriate switching circuit.

Claims

claims

1. A vibration generator of the type comprising a body (3) at least partially made of a magnetizable and movable material along at least one guide element (6) so that its center of gravity can move along a closed curved path, and electromagnetic means making it possible to generate a rotating magnetic field capable of driving said body (3) along the guide elements, characterized in that:

the electromagnetic means consist of a central core (2), said body (3) has a hollow shape surrounding said core (2) and subjected to the rotating magnetic field produced by the latter,

- Said guide means (6) comprise a guide track on which is supported, at all times, a different generator of an annular zone of the internal surface of said body, when said body is driven by said magnetic field.

2. Generator according to claim 1, characterized in that the above path is circular.

3. Generator according to one of claims 1 and 2, characterized in that it comprises a hollow cylindrical casing forming an envelope (1), in which the above-mentioned body (3) is driven along a concentric raceway to the envelope (1) by the above electromagnetic means.

4. Generator according to one of the preceding claims, characterized in that the above electromagnetic means comprise an inductor or stator (2) coaxial with casing and wound so as to have alternating polarities (N, S).

5. Generator according to claim 1, characterized in that the aforesaid core (2) comprises notches (Ti to T4) axial delimiting polar expansions around which are wound windings.

6. Generator according to claim 5, characterized in that the aforesaid body (3) constituting the rotor forms a crown suspended by an internal bore on the stator formed by the central core (2), via a cylindrical sheath (4) of thickness equal to an air gap ("e") to be respected, the external wall of said sheath (4) constituting the raceway on which the bore of said crown rolls.

7. Generator according to claim 5, characterized in that the aforesaid body (3) constituting the rotor forms a crown of which an external wall (3b) rolls on the internal bore (la) of the casing (1), the diameter internal ("D") of this crown being determined so as to leave a permanent air gap ("e") between the outer wall (3a) of the body and the bore (2a) of said crown.

8. Generator according to claim 1, characterized in that the active part of the above-mentioned body (3) is equipped with permanent magnets (A to F, G to J), the pitch of which is identical to that of the stator windings.

9. Generator according to claim 1, characterized in that the active part of the aforesaid body (3) comprises axial recesses (31 to 36, 201 to 204), the pitch of which is identical to that of the stator windings.

10. Generator according to one of the preceding claims, characterized in that the guide track of the said body consists of non-magnetic rings (40, 40 ') interposed, at each end of the stator (2), between said body (3 ) and said stator (2).

11. Generator according to claim 5, characterized in that the aforesaid body (3) rolls on two discs (8, 9) respectively arranged at the end of the central core (2).

12. Generator according to claim 1, characterized in that the above path is oval.

13. Generator according to claim 12, characterized in that it comprises a central stator (2) of oval section around which rolls an annular rotor (3).

14. Generator according to claim 4, characterized in that it comprises an annular rotor (3) of oval section, which rolls by its inner surface on a central stator (2), of cylindrical shape.

15. Generator according to claim 1, characterized in that it comprises a rotor of cylindrical shape rolling, by its two ends (51, 52), on two respective raceways (53, 54) mobile coaxial 1'un relative to the other so that they can adjust their spacing.

16. Device for generating unidirectional vibrations, characterized in that it comprises at least two mutually integral generators produced in accordance with one of the preceding claims, and the rotors of which rotate in opposite directions.

17. Device according to claim 16, characterized in that it comprises two pairs of généra¬ ^tors' 1'une according to the preceding claims, oriented parallel to one another and oriented in the same direction, the two structures of the same pair presenting:

- rotors (44, 45 - 46, 47) rotating, synchronously, in the same direction which is opposite to the direction of rotation of the rotors of the other pair, - the same plane of symmetry (Pi, P'i - P2, P'2) passing through the major axes of their central nuclei (40, 41 - 42, 43),

- two respective parallel planes of symmetry (P3, P'3 - P4, P'4) passing through the minor axes of their central nuclei (40, 41 - 42, 43), these two planes being merged with the corresponding planes of symmetry structures of the other pair.

18. Device according to claim 16, characterized in that the excitation cycles of the windings of the central cores of the two generators are out of phase as a function of the amplitude of the oscillations that it is desired to obtain.