MAGNETORHEOLOGICAL BRAKE SYSTEM

Abstract

A magnetorheological braking system (1) comprising a rotor and a stator, each having at least one ring (2), the rotor ring (2a) and the stator ring (2b) each having a complementary geometry, and the rotor ring (2a) and the stator ring (2b) being separated from each other by a magnetorheological fluid. Each ring (2) has a surface (4) having at least one inflection (6) in an axial plane (P) including a rotor axis (A). Figure to be published with the abbreviation: Fig. 2

Description

Title of the invention: MAGNETO-RHEOLOGICAL BRAKE SYSTEM technical field

[0001] The invention relates to the field of magnetorheological braking systems. STATE OF PRIOR ART

[0002] In a known manner, magnetorheological brakes comprise a stator and a rotor pivoting within the stator. The rotor and stator are separated by a magnetorheological fluid. It is known that a magnetorheological fluid is a fluid whose viscosity increases considerably (to the point of becoming viscoelastic solid) when it is subjected to a magnetic field.

[0003] Currently, numerous variations of magnetorheological braking systems are known. One example is US patent 14960482, which proposes combining a magnetorheological brake with a return spring. However, this solution requires the constant use of an electric motor to maintain a constant torque on the braking system. This consumes energy, wears out the electric motor, and generates heat loss.

[0004] The majority of known magnetorheological braking systems use a welded assembly of sheet metal rings. However, welded assemblies are expensive because they require numerous complex assembly operations. Furthermore, this type of assembly introduces weaknesses in the weld interface areas. Thus, the fragility of this type of assembly prevents the generation of optimal braking torque.

[0005] In this context, it is necessary to provide a magnetorheological braking system which provides a braking torque greater than the braking torque of known welded assemblies and which is simpler, faster and less expensive to manufacture. Description of the invention

[0006] To this end, according to a first aspect, a magnetorheological braking system is proposed comprising a rotor and a stator mounted movably relative to each other about a rotor axis of rotation, and mounted one inside the other, the rotor and the stator each having at least one ring, the rotor ring and the stator ring each having a complementary geometry, and the rotor ring and the stator ring being separated from each other by an air gap intended to contain a magnetorheological fluid. Each ring has a surface of which a geometry neratrice, in an axial plane including the axis of rotation of the rotor, has at least one non-zero derivative.

[0007] The specific geometry of the rings increases the surface area of ​​each ring, compared to known devices, to maximize the contact of each ring's surface with the magnetorheological fluid and thus maximize the braking torque developed by the braking system. Furthermore, the specific geometry of the rings can be produced using a traditional or additive manufacturing process. Thus, the magnetorheological braking system provides a braking torque higher than that of known welded assemblies.

[0008] According to a particular arrangement, each ring has at least one toroidal surface centered on the axis of rotation.

[0009] According to a particular arrangement, the surface of each ring presents a plurality of successive toroidal surfaces along the direction of the axis of rotation.

[0010] According to a particular arrangement, the surface of each ring is formed of a plurality of successive toric surfaces alternating concave toric surfaces and convex toric surfaces.

[0011] According to a particular arrangement, the surface of each ring has a plurality of inflections in the axial plane, so that the surface of the ring is formed of a plurality of successive conical surfaces along the direction of the axis of rotation.

[0012] According to a particular arrangement, the surface of the crown has a roughness Ra of at least 3.2 pm, and preferably of at least 20 pm.

[0013] According to a particular arrangement, the surface of the crown has a raised or recessed texture, such as undulations, bumps, random shapes, or striations.

[0014] According to a particular arrangement, the rotor ring and / or the stator ring comprise at least two portions assembled together.

[0015] According to a particular arrangement, the two portions are nested one inside the other according to a tongue and groove assembly, a first portion having a groove and a second portion having a tongue adapted to be nested in the groove.

[0016] According to a particular arrangement, the brake system comprises a radial stack of several rotor rings nested with a radial stack of several stator rings.

[0017] According to another aspect, a manufacturing method for a brake system according to the invention is proposed, the method comprising a co-generated additive manufacturing step of the rotor ring and / or the stator ring. Brief description of the drawings

[0018] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of at least one exemplary embodiment, said description being made in relation to the accompanying drawings, among which:

[0019] [Fig-1] schematically illustrates, in perspective, a crown of a rotor and a crown of a stator, according to an embodiment of a braking system according to the invention;

[0020] [Fig.2] schematically illustrates, in cross-section, a ring of a rotor and a ring of a stator, according to an embodiment of a brake system according to the invention;

[0021] [Fig.3] schematically illustrates a ring of a rotor and a ring of a stator, according to an embodiment of a brake system according to the invention;

[0022] [Fig.4] schematically illustrates, from above, a ring of a rotor and a ring of a stator, according to an embodiment of a brake system according to the invention;

[0023] [Fig. 5] schematically illustrates a tongue and groove assembly of two portions of a crown according to an embodiment of a brake system according to the invention; and

[0024] [Fig.6] schematically illustrates the assembly of crowns in two portions, according to an embodiment of a brake system according to the invention.

[0025] DETAILED DESCRIPTION OF IMPROVEMENTS

[0026] Magnetorheological braking system

[0027] With reference to [Fig. 1], according to a first aspect, a magnetorheological brake system 1 is proposed comprising a rotor and a stator mounted movable relative to each other about an axis A of rotation of the rotor, and mounted one inside the other. The rotor and the stator each have at least one ring 2a-b. Preferably, the rotor is made of magnetic material.

[0028] The rotor ring 2a and the stator ring 2b each have a complementary geometry. As schematically illustrated in particular in [Fig. 1], the rotor ring 2a is inserted into the stator ring 2b (or vice versa), so as to be free to rotate relative to each other around the rotor's axis of rotation A. According to a particular arrangement, the rotor ring 2a and the stator ring 2b each have a geometry that is complementary and homothetic to each other. In other words, the stator (or rotor) ring 2b is a hollow structure whose geometry is an enlargement of the geometry of the rotor ring 2a (or the corresponding stator ring).

[0029] The rotor ring 2a and the stator ring 2b are separated by an air gap 14 (i.e. a space) in which a magnetorheological fluid is positioned.

[0030] As previously stated, the magnetorheological fluid's viscosity changes when subjected to a magnetic field, eventually becoming viscoelastic, which enables braking. The behavior of the magnetorheological fluid is known and will not be detailed below. Furthermore, to subject the magnetorheological fluid to a magnetic field, the braking system 1 includes a magnetic field generation device, the conventional structure of which will not be described in this document.

[0031] In a particularly ingenious manner, each ring 2a-b has a surface 4, one generatrix of which, in an axial plane P including the axis A of rotation of the rotor, has at least one non-zero derivative. In other words, in the axial plane P, a generatrix of the surface 4 of each ring 2a-b has at least one change of direction (i.e., a curvature and / or an inflection) in the axial plane P. Put another way, in the axial plane P, the generatrix of the surface 4 of each ring 2a-b is not a straight line. Thus, the rings 2a-b are not right cylinders of revolution according to the mathematical definition of a cylinder as a ruled surface whose generatrices are parallel lines.

[0032] In a particularly advantageous manner, the geometry of the surfaces 4 of the braking system 1 according to the invention maximizes the area of ​​each surface 4. Indeed, the presence of a curvature and / or an inflection of the generatrix of the surface 4 in the axial plane P allows the surface 4 to have a larger area than a surface with a straight generatrix in the axial plane P. Now, the larger the area of ​​the surface 4, the larger the friction surface between the magnetorheological fluid and the rotor ring 2a and the stator ring 2b, which maximizes braking. Thus, the invention provides a braking system that delivers a braking torque greater than that of known welded assemblies.

[0033] Thus, in other words, the invention proposes a braking system 1 in which the geometry of the shapes of the rotor ring 2a and the stator ring 2b has been optimized taking into account the criteria of mass, ease of assembly or manufacture, volume constraint and pivoting of the surfaces relative to each other over 360 degrees while allowing the circulation of a magnetorheological fluid which ensures the mechanical braking function and maintaining the air gap 14 between the rings 2a-b.

[0034] Toric surface

[0035] According to an embodiment schematically shown in Figs 3, 4 and 6, the surface 4 of each ring 2a-b has at least one toroidal surface 4 centered on the axis A of rotation of the rotor. In a particularly advantageous manner, the toroidal surfaces 4 maximize the area of ​​the surfaces 4 (compared to a cylindrical surface of the prior art), so as to optimize the braking of the braking system 1.

[0036] According to a further particular embodiment, the surface 4 of the rotor ring 2a is a convex toroidal surface 4 and the surface 4 of the stator ring 2b is a concave toroidal surface 4. In other words, the toroidal surface 4 of the rotor ring 2a is complementary to the toroidal surface 4 of the stator ring 2b.

[0037] According to a particular embodiment (not shown), the surface 4 of each ring 2a-b has a plurality of successive toric surfaces 4 along the direction of the axis A of rotation.

[0038] According to an even more particular embodiment, the surface 4 of each ring 2a-b is formed of a plurality of successive toric surfaces 4 alternating concave toric surfaces 4 and convex toric surfaces 4.

[0039] Plurality of inflections

[0040] According to a particular embodiment, schematically shown in Figs. 1 and 2, the surface 4 of each ring 2a-b has a plurality of inflections 6 in the axial plane P, so that the surface 4 of the ring 2a-b is formed of a plurality of successive conical surfaces 4 along the direction of the axis A of rotation.

[0041] In other words, as schematically shown in [Fig.2], according to this embodiment, a generatrix of the surface 4 in the axial plane P is a broken line having a sawtooth profile.

[0042] This technical arrangement is particularly advantageous because it allows maximizing the surfaces 4 (compared to a cylindrical surface of the prior art), so as to optimize the braking of the braking system 1.

[0043] As will be detailed below, such surfaces 4 can be produced using an additive manufacturing process.

[0044] Texture

[0045] According to a particular arrangement, the surfaces 4 can be textured. In other words, the surfaces 4 can have raised patterns, asperities. The texture of each surface 4 is such that each surface 4 has a roughness Ra of at least 3.2 pm and at least 20 pm. Even more preferably, the roughness Ra can be at least 25 pm.

[0046] Assembly of surface portions

[0047] According to a particular arrangement, one of the rotor and / or stator rings 2a-b comprises at least two portions 8 assembled together. This embodiment is particularly suitable when the rings 2a-b are made of bent sheet metal.

[0048] Typically, as schematically shown in Figs. 5 and 6, the two portions 8 are nested one inside the other according to a groove 10 and tongue 12 assembly, a first portion 8b having a groove 10 and a second portion 8a having a tongue 12 adapted to be nested in the groove 10.

[0049] As schematically shown in [Fig.6], the assembly of the two portions 8 can be normal to a radial plane of each ring 2. This arrangement allows for a simpler assembly than known welding methods which are complex to implement and induce areas of weakness.

[0050] In addition, this arrangement makes it easier to assemble the crowns 2, in particular when the brake system 1 comprises a plurality of crowns, as will be described below.

[0051] Stacking of several crowns

[0052] According to a particular arrangement, as shown in Figs. 3 and 4, the brake system 1 comprises a radial stack of several rotor rings 2a nested with a radial stack of several stator rings 2b.

[0053] The use of a nested ring 2a-b, each having at least one curvature (or inflection 6) in the axial plane P, is a particularly ingenious arrangement that maximizes the area of ​​the surfaces 4 in contact with the magnetorheological fluid, thereby optimizing braking. Indeed, the larger and more numerous the surfaces 4 in contact with the magnetorheological fluid, the more effective the braking.

[0054] Manufacturing process

[0055] According to another aspect, the invention relates to a method for manufacturing the brake system 1.

[0056] The process includes a co-generated additive manufacturing step of the rotor ring and / or the stator ring.

[0057] It is specified that by cogenerated additive manufacturing, it is understood that at least one ring 2a of the rotor and at least one ring 2b of the stator are manufactured during the same additive manufacturing operation, which allows them to be manufactured nested.

[0058] Thus, the production of the crowns by additive manufacturing makes it possible to manufacture at the same time all the crowns 2a-2b of the brake system 1, which allows the crowns 2a-b to have surfaces 4 presenting at least one inflection 6 in the axial plane P, because not constrained by the assembly of the brake system 1. Indeed, additive manufacturing makes it possible to produce complex parts having shapes which would be difficult to produce or assemble together according to other manufacturing processes.

[0059] In a particularly advantageous manner, the additive manufacturing step can be carried out, for example, using: a laser powder bed fusion process, a fused filament deposition process, a binder jetting process, or a direct energy deposition process. The additive manufacturing processes listed here are only examples; the additive manufacturing step can be carried out using any additive manufacturing process.

Claims

Claims

1. Magnetorheological brake system (1) comprising a rotor and a stator mounted to move relative to each other around an axis (A) of rotation of the rotor, and mounted one inside the other, the rotor and the stator each having at least one crown (2a-b), the crown (2a) of the rotor and the crown (2b) of the stator each having a complementary geometry and the crown (2a) of the rotor and the crown (2b) of the stator being separated from each other by an air gap (14) intended to contain a magnetorheological fluid, the brake system (1) being characterized in that each crown (2) has a surface (4) of which a generatrix, in an axial plane (P) comprising the axis (A) of rotation of the rotor, has at least one non-zero derivative.

2. Brake system (1) according to claim 1 wherein the surface (4) of each crown (2) has at least one toric surface (4) centered on the axis (A) of rotation.

3. Brake system (1) according to claim 2, in which the surface (4) of each crown (2) has a plurality of successive toric surfaces (4) in the direction of the axis (A) of rotation.

4. Brake system (1) according to claim 3, wherein the surface (4) of each crown (2) is formed of a plurality of successive toric surfaces (4) alternating concave toric surfaces (4) and convex toric surfaces (4).

5. Brake system (1) according to claim 1, wherein the surface (4) of each crown (2) has a plurality of inflections (6) in the axial plane (P), so that the surface (4) of the crown (2) is formed of a plurality of successive conical surfaces (4) in the direction of the axis (A) of rotation.

6. Brake system (1) according to any one of the preceding claims, wherein the surface (4) of the crown (2) has a roughness Ra of at least 3.2 pm, and preferably at least 20 pm.

7. A brake system (1) according to any preceding claim, wherein the surface (4) of the crown (2) has a raised or hollow texture, such as undulations, spikes, random shapes, or grooves.

8. Brake system 1 according to any one of the preceding claims, wherein the crown (2a) of the rotor and / or the crown (2b) of the stator comprise at least two portions (8a-b) assembled together.

9. Brake system (1) according to claim 8 in which the two portions (8a-b) are nested one inside the other according to a groove (10) and tongue (12) assembly, a first portion (8b) having a groove (10) and a second portion (8a) having a tongue (12) adapted to be nested in the groove (10).

10. Brake system (1) according to any one of the preceding claims comprising a radial stack of several rings (2a) of the rotor nested with a radial stack of several rings (2b) of the stator.

11. Method for manufacturing a brake system (1) according to any one of claims 1 to 10, the method comprising a step of cogenerated additive manufacturing of the crown (2a) of the rotor and / or the crown (2b) of the stator.

Images