MAGNETIC HYSTERESIS BRAKE WITH REDUCED ELASTIC RETURN

Abstract

A magnetic hysteresis brake (10), comprising at least a first member (11.1) carrying first magnets (17.1) and a second member (12) made of magnetic material, each first magnet having a first surface (15.1) facing a first surface (14) of the second member (12) in order to generate a first magnetic flux towards the second member (12) through said surfaces, characterised in that the first magnets (17.1) are separated from one another by magnetic elements (18.1) which are made of a magnetic flux-conducting material and which have a first surface facing the first surface (14) of the second member (12) and close to the first surface (15.1) of the adjacent first magnets (17.1) in order to let pass a second magnetic flux the direction of which is opposite to the first flux of the first adjacent magnets, the first surface of the magnetic elements being of smaller size than the first surface (15.1) of the first magnets. The invention also relates to a control instrument and to a vehicle comprising such a brake.

Claims

1. A magnetic hysteresis brake (10), comprising at least a first member (11.1) carrying first magnets (17.1) and a second member (12) made of magnetic material, each first magnet having a first surface (15.1) facing a first surface (14) of the second member (12) in order to generate a first magnetic flux towards the second member (12) through said surfaces, characterised in that the first magnets (17.1) are separated from one another by magnetic elements (18.1) which are made of a magnetic flux-conducting material and which have a first surface facing the first surface (14) of the second member (12) and close to the first surface (15.1) of the first adjacent magnets (17.1) in order to let pass a second magnetic flux the direction of which is opposite to the first flux of the first adjacent magnets (17.1), the first surface of the magnetic elements (18.1) being of smaller size than the first surface (15.1) of the first magnets (17.1).

2. The brake according to claim 1, wherein the first member (11.1) comprises a framework having teeth forming the magnetic elements (18.1), each first magnet being mounted between two of the teeth, which are adjacent to each other.

3. The brake according to claim 1 or 2, wherein the first member (11.1) and the second member (12) are mounted to rotate relative to each other about an axis of rotation (4).

4. The brake according to claim 3, wherein the first surface (15.1) of each first magnet and the first surface (14) of the second member (12) are cylindrical with a circular cross-section; the first magnets (17.1) of the first member (11.1) being arranged in a cylinder and the first magnetic flux being radial.

5. The brake according to claim 4, wherein the second member (12) is tubular in shape with a circular cross-section and the brake (10) comprises a second first member (11.2) which is arranged in the second member (12) and which has a first surface (15.2) facing a second surface (16) of the second member (12), said second surface (16) of the second member (12) being opposite the first surface (14) of the second member (12).

6. The brake according to claim 3, wherein the first surface (15.1) of the first magnets (17.1) and the first surface (14) of the second member (12) are planar; the first magnets (17.1) of the first member (11.1) being arranged in a circle and the first magnetic flux being axial.

7. The brake according to any one of the preceding claims, comprising a plurality of first members (11.1) and a plurality of second members (12).

8. A control instrument (1) comprising a frame (2), a handle (3) movably mounted on the frame (2), and a brake (10) according to any one of the preceding claims, one of the first member (11.1) and the second member (12) being mounted fixed relative to the frame (2) and the other of the first member (11.1) and the second member (12) being connected to the handle (3).

9. The control instrument according to claim 8, wherein the handle (3) is mounted on the frame (2) to pivot.

10. The control instrument according to claim 9, comprising a gearbox having a first shaft connected to said other of the first member (11.1) and the second member (12) and a second shaft connected to the handle.

11. A vehicle including a control instrument according to any one of claims 8 to 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Reference will be made to the accompanying drawings, in which:

[0027] FIG. 1 is a partial schematic view of a vehicle cockpit, provided with a control instrument, according to the invention;

[0028] FIG. 2 is a perspective view of a brake equipping the control instrument, according to a first embodiment,

[0029] FIG. 3 is a perspective view of a portion of the brake according to the first embodiment;

[0030] FIG. 4 is a perspective view of a brake equipping the control instrument, according to a second embodiment;

[0031] FIG. 5 is an exploded, perspective of the brake according to the second embodiment;

[0032] FIG. 6 is another perspective view of the brake according to the second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0033] With reference to FIGS. 1 to 6, the invention is, in this case, described in application to a control instrument, generally referenced as 1, equipping the cockpit of a vehicle V such as an aerial, land or naval vehicle. The control instrument 1 is, in this case, arranged to control the motor of said vehicle (the control instrument 1 is, in this case, what is commonly called the throttle).

[0034] The control instrument 1 comprises a frame 2, which is fixed to the structure of the vehicle V, in the cockpit, within the pilot's reach.

[0035] A handle 3 is mounted on the frame 2 to pivot about an axis of rotation 4, in this case, horizontal.

[0036] The control instrument 1 further comprises, a brake 10 comprising two stators 11.1, 11.2 rotatably connected to the frame 2 and a rotor 12 rotatably connected to the handle 3. The first stator 11.1 may be referred to as the first member. The second stator 11.2 may be referred to as the second first member. Furthermore, the rotor 12 may be referred to as the second member.

[0037] The brake 10 is a magnetic hysteresis brake.

[0038] According to the first embodiment shown in FIGS. 2 and 3, the rotor 12 in this case is a bell having a cylindrical outer surface 14 and a cylindrical inner surface 16 that is coaxial with the outer surface 14 and defines an inner housing of the rotor 12. The outer surface 14 and the inner surface 16 form major surfaces of the rotor 12.

[0039] The rotor 12 is made of a magnetic material and more particularly, in this case, a semi-remanent material. The material chosen is called semi-remanent as its major hysteresis cycle is close to that of a magnet. The material is, for example, that produced under the trademark MAGNETOFLEX (and more specifically, MAGNETOFLEX 35 U) or CROVAC, by the manufacturer VACUUMSCHMELZE.

[0040] The rotor 12 further comprises a tubular hub which is centred on the axis of rotation 4 and which connects the rotor 12 to the handle 3.

[0041] The stator 11.1 is an outer stator extending around the rotor 12 and the stator 11.2 is an inner stator extending into the housing of the rotor 12.

[0042] The stator 11.1 comprises a cylindrical framework, made of a magnetic flux-conducting material, centred on the axis of rotation 4, and a set of permanent magnets 17.1 which are fixed to the inner periphery of the cylindrical framework so as to have a free surface forming a substantially cylindrical main surface 15.1 of said stator 11.1 surrounding the outer surface 14 of the rotor 12. The framework comprises magnetic elements 18.1 which separate the magnets 17.1 from one another and which have a free surface close to the main surface 15.1 of said stator 11.1. In this case, the magnetic elements are teeth 18.1 integral with the framework.

[0043] The teeth 18.1 are shaped to define therebetween housings for said magnets 17.1 and have widened free ends to project slightly into the housings over opposite side portions of the magnets 17.1. In other words, the magnets 17.1 are held by the teeth 18.1, said teeth 18.1 partly covering the magnets 17.1 in their housings. The free surface of the teeth 18.1 here is flush with the free surface of the magnets 17.1 and therefore, coincides with the main surface 15.1 of the stator 11.1. The teeth 18.1 occupy a smaller portion (or area) in the main surface 15.1 of the stator 11.1 than that of the magnets 17.1. Therefore, the surface (or area) occupied by the magnets 17.1 and therefore, the performance of the brake 10, is optimised to the maximum, the teeth 18.1 being mainly arranged to separate the magnets 17.1 from one another. The magnets 17.1 are positioned so that their magnetisation vector extends in a radial direction of the stator 11.1 to produce a radial or axial magnetic flux in the case illustrated in FIGS. 4 to 6. Furthermore, the magnets 17.1 all have the same pole oriented towards the rotor 12. Each of the teeth 18.1 let pass a second flux the direction of which is opposite to the first flux of the two magnets 17.1 that surround it to allow the magnetic field produced by the two magnets 17.1 to be looped. This architecture allows optimal magnetic flux loop-back.

[0044] The stator 11.1 comprises a cylindrical outer surface 13.1 coaxial with the main surface 15.1 constituting the inner surface of the stator 11.1. The diameter of the main surface 15.1 of the stator 11.1 is slightly greater than the diameter of the outer surface 14 of the rotor 12.

[0045] The stator 11.2 has a structure similar to the stator 11.1 and is coaxial with the latter and the rotor 12. The stator 11.2 is however arranged in the inner housing of the rotor 12 and comprises a framework carrying magnets 17.2 on its outer periphery. The magnets 17.2 have a free surface defining a main surface 15.2 (which is the outer surface of the stator 11.2 and not the inner surface as in the stator 11.1) and having magnetic elements 18.2 separating the magnets 17.2 from one another. In this case, the magnetic elements are teeth 18.2.

[0046] The teeth 18.2 are shaped to define therebetween housings for the magnets 17.2 and have widened free ends to project slightly into the housings over opposite side portions of the magnets 17.2. In other words, the magnets 17.2 are held by the teeth 18.2, said teeth 18.2 partly covering the magnets 17.2 in their housings.

[0047] As previously, the teeth 18.2 have a free surface close to the main surface 15.2 of said stator 11.2. The free surface of the teeth 18.2, in this case, is flush with the free surface of the magnets 17.2 and therefore, coincides with the main surface 15.2 of the stator 11.2. The teeth 18.2 occupy a smaller portion (or area) in the main surface 15.2 of the stator 11.2 than that of the magnets 17.2. Therefore, the surface (or area) occupied by the magnets 17.2 and therefore, the performance of the brake 10, is optimised to the maximum, the teeth 18.2 being mainly arranged to separate the magnets 17.2 from one another. The magnets 17.2 are positioned so that their magnetisation vector extends along a radial direction of the stator 11.2 to produce a radial magnetic flux. Furthermore, the magnets 17.2 all have the same pole oriented towards the rotor 12. This architecture allows optimal loop-back of the magnetic flux.

[0048] The stator 11.2 comprises a cylindrical inner surface 13.2 coaxial with the main surface 15.2 constituting the outer surface of the stator 11.2.

[0049] It can be understood that when the pilot moves the handle 3, the handle 3 moves the rotor 12 in rotation. Under the effect of the rotation of the rotor 12 relative to the stators 11.1 and 11.2, the bell saturates locally opposite the poles, which will generate dry friction.

[0050] It should be noted that the teeth 18.1, 18.2 allow to increase the number of poles, to channel the magnetic flux and to reduce the elastic return. More particularly, the number of poles allows the bell to align more, when it is remanent with the poles.

[0051] In the second embodiment of FIGS. 4 to 6, the stators 11.1, 11.2 and the rotor 12 are not arranged in the same way. Indeed, the stators 11.1, 11.2 and the rotor 12 are disk-shaped and the stators 11.1, 11.2 have plane main surfaces facing opposite plane main surfaces of the rotor 12. As a result, the rotor 12 has a central position between the stators 11.1, 11.2.

[0052] As previously, the main surfaces 15.1, 15.2 of the stators 11.1, 11.2 are formed by the free surfaces of the magnets 17.1, 17.2 which are carried by a framework comprising magnetic elements 18.1, 18.2 separating the magnets 17.1, 17.2 from one another. In this embodiment, as in the previous one, the magnetic elements are teeth 18.1, 18.2 of the framework.

[0053] Teeth 18.1, 18.2 are shaped to carry said magnets 17.1, 17.2. In other words, the magnets 17.1, 17.2 are held by the teeth 18.1, 18.2, said teeth 18.1, 18.2 partially covering the magnets 17.1, 17.2 in their housings. The teeth 18.1, 18.2 have a free surface flush with the main surfaces 15.1, 15.2 of the stators 11.1, 11.2. The teeth 18.1, 18.2 occupy in the main surfaces 15.1, 15.2 of the stators 11.1, 11.2, a smaller portion than that of the magnets 17.1, 17.2. Therefore, the surface occupied by the magnets 17.1, 17.2 and therefore, the performance of the brake 10, is optimised to the maximum, the teeth 18.1, 18.2 being mainly arranged to separate the magnets 17.1, 17.2 from one another. The magnets 17.1, 17.2 of the stators 11.1 and 11.2 are arranged in a circle and have a magnetisation vector parallel to the axis of rotation 4 and the direction of which is oriented towards the rotor 12 to produce an axial magnetic flux.

[0054] The aforementioned friction torque is adjustable by offsetting one stator 11 relative to the other. Particularly, and with reference to FIGS. 2 and 3, each of the teeth 18.1 carried by the stator 11.1 faces one of the teeth 18.2 carried by the stator 11.2. It will be noted that in order to adjust the resistant force, it suffices to offset one stator relative to the other and, for example, to make each tooth 18.1 of the stator 11.1 coincide with one of the magnets 17.2 of the stator 11.2.

[0055] Alternatively, a gearbox may be associated with the brake in order to further reduce the amplitude of the effect of the magnetic elastic return. In such an embodiment, the gearbox comprises a first shaft connected to the rotor and a second shaft connected to the handle. The transmission ratio x of the gearbox, from the handle 3 to the rotor 12, is greater than 1 so that a return of the rotor 12 over an angular amplitude will result in a movement of the handle 3 of a lesser amplitude equal to /x.

[0056] Naturally, the invention is not limited to the embodiments described, but comprises any variant entering into the scope of the invention such as defined by the claims.

[0057] Particularly, the brake can have a different structure from that described above.

[0058] The handle of the control instrument can, for example, be a button, a steering wheel, a lever, or other. The invention is also applicable to rudder controls, and more generally, for any device needing to implement a dry friction.

[0059] The handle can be mounted on the frame to slide along a linear axis.

[0060] The stator can constitute the inner element and the rotor can constitute the outer element, or vice versa. The brake may comprise a stator in the form of a drum and two annular rotors, one extending in the drum and the other around the drum.

[0061] The rotor 12 and the stator 11 can be mounted relative to each other so as to be movable, not only rotatable about the axis of rotation 4, but also translatable along the axis of rotation 4 to allow adjustment of the air gap between the stator and the rotor. To this end, the hub of the rotor 12 is mounted to slide axially over a tubular shaft rotatably connected, in this case, via an inner gearing, to the handle 3 and mounted in the frame 2 to pivot about the axis of rotation 4.

[0062] Alternatively, the stator can be rotatably fixed and translatable, while the rotor is rotatably movable and translatably fixed.

[0063] The rotor can have the shape of a solid cylinder and not a hollow hub.

[0064] The rotor can carry the magnets and the stator can be made of semi-remanent or low-remanent material.

[0065] The number of magnets and therefore teeth, as well as the number of rotor(s) and/or stator(s) depend on the desired performance according to the intended application (braking torque, bulk, mass, effect of magnetic elastic return).

[0066] Another possible architecture may be the successive alternation of a stator and then a rotor, at a frequency defined based on the desired performance depending on the envisaged application.

[0067] The magnets may be fastened by means distinct from the shape of the teeth, for example, by gluing or screwing.

[0068] Alternatively, the teeth can be replaced by second magnets having a polarisation opposite to that of the first magnets: each second magnet is thus passed through by a second flux in the opposite direction to the first flux passing through the two first magnets that surround it.

[0069] Provision can be made for each of the first magnets to have poles of different sizes.