WO2007006730A1 - Device for assisting variation generating movement of a magnetic field - Google Patents

Abstract

The invention concerns a device (10) for assisting the relative movement of two parts of a mechanical system, for example a ball bearing or a gear device, adapted to recover the mechanical energy and convert same into electrical energy. Therefor, at least one among the driving (12, 14) and driven (18) elements of the device comprises a part generating a variable magnetic field during the relative movement of the elements with respect to each other. Coil type means (20) provide the conversion.

Description

 VARIABLE MAGNETIC FIELD GENERATING DEVICE

DESCRIPTION

TECHNICAL FIELD AND PRIOR ART

The present invention relates to systems capable of recovering energy from motions and based on the electromagnetic conversion of a variable field from a mass driven by means movable between them.

A recovery of the energy of a mobile system by magnetic principle has been described in WO 02/103881 or EP 1 429 444: a magnetic mass is driven, by gravity, a movement, in particular oscillation , relative to a fixed guide. This movement causes a variation of the induced magnetic field, variation converted into electrical energy through a winding; the goal is to convert the mechanical energy resulting from the displacement of a magnetic object into electrical energy.

However, it appears that many mechanical systems used move one element relative to another during their operation. For example, a ball bearing comprises two movable parts relative to each other and whose movement causes the displacement of friction-damping elements. These systems are optimized for their function of friction limitations and any ensuing energy loss, with mutual training. SUMMARY OF THE INVENTION

The invention proposes in particular to recover energy from mechanical systems operating with relative drive between several elements. The invention finds particular application for ball bearing-type motion assistance systems, but can be adapted to any similar system of principle.

In one of its aspects, the invention relates to a device comprising two driving parts movable relative to one another and defining a space between them. The device may be of the "ball-bearing" type, with relative rotation between the drive portions that define an annular space, or "slide" type, with translation between two drive parts parallel to each other.

By their movement, the driving elements drive one or more moving members in the space so that they move relative to the driving portions. In particular, the movable elements are spheres or cylinders that roll about an axis. The displacement can be controlled by pinion-type means, with teeth present on the surface of the elements in relation.

At least one of the elements in relation comprises a portion generating a magnetic field that varies during the movement of this element relative to the others. For example, the two parts in relative motion comprise magnetized portions of poles successive alternates, so that the field, orthogonal to the direction of displacement, fluctuates and reverses during the movement. Another possibility is that the rolling elements generate a multipole magnetic field orthogonal to their rolling axis. In the case where a plurality of driven elements follows in space during the relative displacement, it is also possible to alternate by reversing their direction of the bipolar elements along their axis, so that the field fluctuates during their displacement by report to the training parts.

The variation of the magnetic field is converted into electrical energy by appropriate means, for example one or more windings. The coils may be coupled to the driving elements or to the driven elements, in which case they may be integrated or external to them, especially within the space and between two contiguous driven elements. In another aspect, the invention relates to the use of a movement assistance device, in particular a ball bearing or a bearing or a slide, for recovering electrical energy during the movement of the various components of the device. device. The device according to the invention can also be part of a sensor, the variation of the magnetic field making it possible, for example, to obtain information on associated parameters, such as the speed of rotation, the position, etc. BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will be better understood on reading the description which follows and with reference to the accompanying drawings, given by way of illustration and in no way limitative.

Figures IA, IB, IC illustrate various motion assistance systems.

Figure 2 shows an embodiment of a device according to the present invention.

Figure 3 shows another embodiment of a device according to the invention.

FIGS. 4A and 4B show two embodiments of coils integrated in the space of the device.

FIG. 5 shows another embodiment of a device according to the invention.

Figure 6 illustrates different possibilities for the driven elements including a magnetic part.

FIGS. 7A, 7B, 7C show different views of another embodiment of a device according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

In a mechanical system comprising two parts moving relative to one another, devices exist to assist the movement, in particular to limit friction. Thus, as illustrated in FIG. 1A, a device 1, of the bearing or ball bearing type, comprises usually two elements 2, rotatable relative to each other without contact, secured to each of the moving parts of the system, defining between them a space within which one or more driven elements 3, cylindrical or spherical, roll when setting in motion.

It may be advantageous to provide the rolling elements as well as the tooth-driving elements which make it possible to prevent any slipping of the parts in contact and to preserve the interval between each rolling element without using spacing means, such as the device 4 illustrated in FIG. 1B: two drive elements 5 provided with teeth are secured to the parts of the system and define between them a space in which an element 6 provided with teeth cooperating with those of the driving elements 5 can rotate.

These two illustrative examples may have many variations. The rotational bearing of FIG. 1A can thus be produced as a sliding support, with two plane surfaces movable in translation, one parallel to the other, driving cylinders located between them, in the manner of displacement on wooden logs. . Another embodiment, illustrated in FIG. 1C, concerns the presence of a guide cage for a spherical driven element 7 comprising relatively movable elements, here two movable rods 8 with respect to a third 9. Moreover, all the elements 2, 5, 8, 9 or some of them may be part of the mechanical system as such, the assistance being provided by the single driven member 3, 6, 7.

The invention can be applied to all these devices 10, examples of which are illustrated in FIGS. 2, 3, 5, 7, independent or assisting the movement of more complex systems, which comprise at least two movable drive elements 12, 14 relative to each other and defining a space 16 between them, in which at least one driven member 18 moves in rotation during the relative movement of the driving elements 12, 14. The driven elements 18 are not in fact linked to each of the driving surfaces only by mechanical contact. The sizing of the various elements 12, 14, 18 and their shape depend on the use made of the device 10.

According to the invention, at least one of the driven or driving elements comprises a part generating a magnetic field in one or more directions. During the relative movement of the elements 12, 14, 18 between them, a variation of the field in time and / or in space is generated; it is converted into electrical energy by appropriate means 20, for example using a magnetoelectric material, or one or more magnetic coils.

The usual techniques can be used to produce the devices 10 according to the invention, in particular mechanical machining (milling machine, lathe, electroerosion, ...) or molding. allow the different elements to be realized, and the magnetization of certain parts can be obtained by applying, for example, an intense field during the cooling of the elements concerned previously brought to a temperature above the Curie point.

The energy conversion means 20 depends on the use, as does their location on the device. For example, the coils 20 may be external, fixed on one or more of the driving elements 12, 14; they can be secured to the driven elements 18, in the space 16 or outside, and thus partly movable relative to the drive elements 12, 14. It is also possible to use the magnetic field variation within even of the driven member 18 to generate electrical energy usable directly therein. The winding or windings 20 have a relative movement with respect to the magnets; different embodiments will be illustrated. According to one option, the magnetic field is created by the driving elements 12, 14 and varies during their relative movement. In this case, at least two movable drive elements relative to each other comprise means generating a magnetic field whose directions are alternated along the direction of movement. In particular, the two drive elements 12, 14, as illustrated in FIG. 2, comprise magnetized parts alternating their North / South poles. The first drive element 12, considered fixed, comprises a succession of North / South poles; the second training element 14 is mobile in translation parallel to the first and includes the same succession of North / South poles. During displacement, the generated magnetic field is reversed locally. Furthermore, in the space 16 rolls at least one element 18, which is driven by mobile contact without sliding during the relative displacement of the drive elements; the driven member 18 may be ferromagnetic, magnetized or unmagnetized. The energy recovery is here direct at the rolling element 18: a coil 20 is placed in the driven elements 18 which can thus have electrical energy within them, for example to supply an operating sensor. To better channel the field lines, it is preferable to add a ferromagnetic material 22 to the middle of the winding 20.

It is often preferable to recover electrical energy via a coil 20 outside the rolling elements 18 to dispose of it on one of the drive elements. For this purpose, the conversion means 20 may be coupled to one of the two drive elements. It is also possible to locate the coil 20 in the space 16, between the rolling elements 18. For example, as shown in FIG. 3, the driving elements 12, 14 comprise alternating North / South poles and drive in rotation a line of rolling elements 18. Windings 20 are placed between the rolling elements 18, preferably in even numbers, and of alternating direction; the point or cross placed on the coils 20 in the figures indicate the winding direction of the turns. During the rotation of one of the driving elements 14 relative to the other 12, the driven elements 18 are subjected to polarities North / South which alternate in time, and generate across the windings 20 a electromagnetic force that can be used to power an electrical circuit.

Advantageously, in particular in this embodiment, the periodicity of the North / South poles of the drive elements 12, 14 is chosen equal to the distance separating the rolling elements 18 so that each rolling element 18 channels at a given instant. a magnetic field of the same amplitude, facilitating the series or parallel winding 20. It is also preferable that the distances between the rolling elements 18 do not change during operation: the spacing can be provided by mechanical means and / or directly by the windings 20.

The coils 20 located in the space 16 at the level of the rolling elements 18 can be individual, that is to say that each driven element 18 is surrounded by a winding 20A, which can then be associated in series or in parallel, or even managed individually: Figure 4A. It is also possible to have a winding 2OB made in one single block around all the rolling elements 18: FIG. 4B.

Although represented by "ball-bearing" type, it is clear that the embodiment of FIG. 3 can be adapted and used for a planar support sliding in translation with respect to a second driven element, as in Figure 2, and vice versa.

According to another embodiment, it is possible to "reverse" the arrangement of the parts generating a magnetic field, that is to say to cause the modification of the magnetic field by the use of magnetized driven elements 18 of which the setting in motion causes a variation of the relative position of the poles. In particular, as shown in FIG. 5, the two driving elements 12, 14 sliding relative to one another define a space 16 in which elements 18, for example cylindrical, are driven by a rotational movement about their axis and relative translation with respect to the direction of sliding. In the presence of a single driven element, it is thus important that the magnetization of the rolling element 18 is oriented so that the translation and / or rotation causes a variation of orthogonal flow to the driving surfaces 12, 14 Moreover, in the presence of several magnetized elements 18 which follow one another during displacements, preferably an alternating orientation is placed in such a way that they introduce into the part of the winding 20 placed between two consecutive elements a force electromagnetic in the same direction; if it is desired to put the coils 20 in series or in parallel, it is recommended to synchronize the magnetic orientations of the rolling elements 18. In order to increase the flux passing through the coils 20, it is preferable to carry out the driving elements 12, 14 with ferromagnetic materials.

The driven elements 18 have been shown as bipolar cylinders oriented orthogonal to their axis of symmetry. Other geometries of the polarity can be used; FIG. 6 thus illustrates a multipole cylinder oriented orthogonally to its axis of symmetry 18A, a bipolar sphere oriented orthogonally to its axis of symmetry 18B, a bipolar pinion oriented orthogonal to its axis of symmetry 18C, but all combinations are conceivable.

Moreover, in the case where a succession of rolling elements is provided, it is also possible to use a plurality of bipolar cylinders 18D oriented along their axis of symmetry, and to alternate their orientation. One embodiment is illustrated in FIGS.

FIG. 7A also illustrates an alternative positioning of the windings 20 for converting the energy, external to the space 16 and secured to a driving portion, advantageously non-movable 12; the connection between the coil 20 and one of the drive elements 12, 14 may be effected for example by an integral mechanical support. It is possible to couple the coil 20 and the magnetic circuit between each possible North / South pair, on the front face, on the rear face, or between faces; the outputs can be combined in series and / or parallel depending on the need, that is to say the system to supply electrical energy. For to increase the magnetic flux passing through the winding 20, here too, it is possible to add a ferromagnetic material 22 bonded to the central part of the winding 20 (FIG. 7B). In this embodiment also, the relative displacement of the magnetized portions 18 with respect to the surfaces 12, 14 presents to the coil 20 a variable magnetic field generating an electromagnetic force E and a current I if this coil 20 is connected to a load.

For this embodiment, for example, the axial driving portion 14 may be 4 cm in diameter, for an outer casing 12 with a thickness of 1 cm, an internal diameter of 6 cm and a length of 2.5 cm. The rolling elements 18 can thus be cylinders with a diameter D = 1 cm and a length L = 2 cm: it is preferable for the rolling elements 18 to be shorter than the driving elements 12, 14 so that they are not do not go out; guiding excess thicknesses 24 may be provided to maintain the cylinders 18 in the annular space 16. The ferromagnetic element 22 preferably has a volume of the order of magnitude of the rolling elements 18, or less, just like the winding 20. For this embodiment, the following performances can be considered: FIG. 7C shows the two configurations for which the magnetic field B _max inside the coils is maximum and of opposite sign. Between these two extremes, the field crossing the magnetic circuit can be considered sinusoidal of frequency f. The permeability of magnetic circuit is chosen much higher than that of the magnet 18, and its participation in the total reluctance can be considered negligible. The available magnetic energy is π-fLSB ² then: P≈ ² ^, with μ ₀ air permeability and

Section S of the magnet 18 (S = π D ^2/4).

For a maximum field B _max = 1 T, the magnetic power is 3.93 W / Hz. If the bearing 10 comprises six driven magnetic elements 18 associated with three ferromagnetic element 22 / coil 20 systems, the field variation frequency is equal to 1.5 times the rotation frequency of the driving element 14, and the power Magnetic available is equal to 17.7 W per rps, or 442 W for a speed of 1500 r / s.

Because of the losses due to the winding resistance, it is reasonable to consider recovering about half of this energy with a winding volume 20 of the order of magnitude of that of the rolling magnets 18. The power recovered is therefore much higher than that usually required to operate a sensor. Moreover, in this optical recovery only to power a sensor, it is sufficient to place only one magnetic circuit / winding system, or even to keep only the winding to capture the unchanneled flow variations near the sensor. rolling magnets, completely freeing the magnetic circuit. It should be noted that the dimensioning can take varied values depending on the use: the dimensions can notably be greatly increased for truck-type vehicle axles, or strongly restricted for clock applications. The higher the diameter of the axis 14, calculated as a function of the torque to be transmitted, the larger the bearing 10, and the greater the torque that can be absorbed, and the greater the electrical power available after conversion is important.

According to the invention, it is possible, from the variation of a magnetic field in the time and / or the space obtained from one or more ferromagnetic and / or magnetic elements set in rolling or sliding movement between at least two relatively movable surfaces relative to each other, to generate usable electrical energy to power an electronic circuit, a sensor, or other. It is also possible to use the device according to the invention as direct sensor of physical measurements, to know for example the speed and / or the position of the driving elements, possibly the mechanical vibrations: it is sufficient to recover the electrical signal in output of a winding adapted to the desired use.

It is possible to guide and feed a moving part through bearings whose ferromagnetic rolling elements and / or magnetized are coupled to a magnetic winding or other. In addition, the devices according to the invention are capable of operating in reverse, that is to say of generating a mechanical movement from a source of electrical energy.

The rolling parts are thus, according to the invention, the object of a dual use, mechanical guide and variable field generator. If the rotational speed is increased, particularly if the rolling parts are small in relation to the driving system, a minimization of the volume of the magnetic winding necessary to provide a given electrical power is obtained with respect to a magnetic system which would be realized directly by the two driving parties.

Claims

A variable magnetic field generating device (10) comprising at least two driving elements (12, 14) movable relative to each other and defining a space (16) therebetween, at least one driven element ( 18) by the movement of the drive elements (12, 14) located in the space (16) and movable relative to the driving elements (12, 14), in which one of the elements (12, 14, 18) at least comprises a magnetic field generating portion that varies with the relative movement of this element relative to the others. 2. Device according to claim 1 wherein the space (16) is annular and the drive elements (12, 14) are rotatable relative to each other. 3. Device according to claim 1 wherein the drive elements (12, 14) are planar and move in translation one parallel to the other. 4. Device according to one of claims 1 to 3 wherein the driven elements (18) are spherical and move rolling in one space (16). 5. Device according to one of claims 1 to 3 wherein the driven elements (18) are cylindrical of revolution and move in space (16) by rotating about their axis. 6. Device according to claim 5 wherein the driven elements (18) comprise teeth on their surface which cooperate with teeth placed on the driving surfaces of the driving elements (12, 14). 7. Device according to one of claims 4 to 6 wherein the driven elements (18) comprise a portion generating a multipolar magnetic field orthogonal to their rolling axis. 8. Device according to one of claims 1 to 7 comprising a plurality of driven elements (18) magnetized multipole, two elements contiguous in the direction of their displacement generating an opposite magnetic field. 9. Device according to one of claims 1 to 8 wherein two driving elements (12, 14) movable relative to each other comprise a magnetic field generating portion whose poles are alternated along the direction of movement. 10. Device according to one of claims 1 to 9 further comprising means (20) for converting into electric energy the variation of the magnetic field generated by the relative movement. The device of claim 10 including a coil (20) for converting the integrated magnetic field variation to each driven member (18). 12. Device according to claim 10 comprising a plurality of driven elements (18) and wherein the means for converting comprise at least one coil (20). The device of claim 12 comprising a plurality of spaced-apart windings (20) (16) surrounding each driven member (18). 14. Device according to claim 12 comprising a coil (20) located in the space (16) and surrounding several successive driven elements (18). 15. Device according to claim 12 comprising at least one coil (20) coupled to a driving element (12) so as to cover the interval between two consecutive driven elements (18). 16. Physical measurement sensor comprising a device according to one of claims 1 to 15, the variable magnetic field being able to recover information on the state of the sensor. 17. Use of a motion assistance device (10) comprising a portion generating a variable magnetic field during movement to recover electrical energy. 18. Use according to claim 17 wherein the assistance device is a ball bearing. 19. Use of a device according to one of claims 1 to 16 comprising generating a mechanical movement between two drive parts from an electrical energy.