BRAKING SYSTEM THAT INCLUDES MAGNETS

Description

[0001] An electric motor converts electrical energy into mechanical energy. This mechanical energy can be expressed as the product of torque and angular displacement (rotation) for rotary electric motors, while linear motors produce mechanical energy corresponding to the product of force and linear displacement.

[0002] An electric motor consists of a stator and a rotor. The rotor is the part that moves relative to the stator. It typically comprises a set of coils connected to a rotating commutator. In a permanent magnet electric motor, the current flowing through the rotor windings creates a magnetic field that interacts with the permanent magnetic field of the stator to rotate the central shaft.

[0003] The stator is the stationary part of the motor. Depending on the machine's configuration, the stator can create a magnetic field which, through interaction with the rotor's magnetic field, produces electromechanical torque. The stator is therefore generally equipped with magnets, which can be permanent magnets or electromagnets.

[0004] It is therefore necessary to equip the stator or rotor with magnets during its design by attaching them to the frame of the stator or rotor.

[0005] For optimal conversion of electrical energy into mechanical energy, the magnets must be positioned at precise locations on the frame in a specific orientation unique to each magnet. To achieve this, each magnet is individually attached to the frame.

[0006] However, the geometry of the rotor or stator housings makes installation difficult for the operator. They must adapt to each geometry and each type of magnet. Furthermore, if permanent magnets are used, they become magnetized during installation within the housing, making them difficult to handle.

[0007] A flexible strip to which magnets and spacers are attached by gluing is disclosed in US 2015 / 0089794 A1.

[0008] One aim of the invention is to facilitate the manufacture of electric motors.

[0009] For this purpose, according to the invention, an assembly according to claim 1 is provided.

[0010] Thanks to this assembly, it is possible to position all the ferromagnetic elements on the strip, then fix them all to it before assembling the strip to a support, such as the frame of a rotor or stator. The operator can therefore perform the positioning and fixing steps flat on a work surface. This greatly improves their comfort and safety. The strip can be manufactured in advance and stored as a roll or reel. Another technical advantage of this solution is that different types of ferromagnetic elements can be used for the same strip. A single roll can therefore be used to equip different motors. Conversely, the roll can be custom-made to fit the planned arrangement of the magnets for a particular motor, dedicated to that specific motor. Thus, a single operator can perform a manufacturing step for a greater number of different types of electric motors.Finally, since the step of attaching the magnets to the strip and the step of attaching the magnets to the casing do not take place simultaneously, it is possible to sequence the steps of manufacturing the motor, which means time and economic gains.

[0011] Thanks to the adhesive methods, the strip is easier to assemble onto a support.

[0012] Preferably, the ferromagnetic elements are arranged with a constant pitch along the strip.

[0013] Preferably, the ferromagnetic elements form groups of at least two ferromagnetic elements, these groups being arranged with a constant pitch along the strip.

[0014] The spacers are used to hold the ferromagnetic elements in position.

[0015] The invention also provides for an assembly in which the ferromagnetic elements form permanent magnets.

[0016] An electric motor component, such as a stator or rotor, can be provided, comprising an assembly according to the invention.

[0017] An electric motor equipped with such a component can be envisioned.

[0018] Advantageously, the engine is also equipped with magnetic shielding.

[0019] This magnetic shielding can be achieved using any type of ferromagnetic material with high magnetic susceptibility and a low coercive field. For example, the material used can be iron, nickel, cobalt, or combinations of different materials such as iron-silicon, or those marketed under the names Mumetal, Supermumetal, Cryophy, Supra50, and Supra36 by Aperam.

[0020] Claim 5 also provides for a braking system equipped with brakes and such an electric motor.

[0021] Claim 6 also provides a method for manufacturing an electric motor.

[0022] Advantageously, the process includes a subsequent step in which the ferromagnetic elements are magnetized so that they become permanent magnets.

[0023] Thus, the ferromagnetic elements are only magnetized at the final stage of the manufacturing process. This greatly improves their handling in all the stages preceding magnetization.

[0024] Advantageously, the fixing step includes crimping.

[0025] According to the invention, the bonding is achieved using a heat-cured adhesive. The polymerization temperature is greater than or equal to 70°C, preferably 100°C, and even more preferably 150°C.

[0026] Furthermore, advantageously, the bonding is achieved using a flexible adhesive, preferably a flexible adhesive made of elastomers.

[0027] Advantageously, the step of attaching the strip to the stator or rotor is carried out by means of gluing.

[0028] Adhesive fixing avoids altering the mechanical structure of the rotor or stator and does not influence its electromagnetic behavior.

[0029] The invention also provides for a method of manufacturing a braking system comprising a method of manufacturing an electric motor according to the invention.

[0030] It is also anticipated that the manufacturing process of the electric motor according to the invention includes a step in which magnetic shielding of the motor is carried out.

[0031] We will now present an embodiment of the invention given by way of non-limiting example and supported by the attached figures in which: there figure 1 is a top view of the flexible band according to one embodiment of the invention; the figure 2 is a larger-scale view of part of the band of the figure 1 ; there figure 3 is a perspective view of an electric motor component equipped with the band of the figure 1 ; there figure 4 is an axial cross-sectional view of the organ shown in the figure 3 . there figure 5 is a diagram representing a braking system equipped with an electric motor, with the electric motor component illustrated in figures 3 et 4 .

[0032] There figure 1 presents an assembly 1 according to this embodiment. It comprises a flexible strip 2 to which ferromagnetic elements 4 and spacers 6 are attached. The strip may be made of plastic, resin, silicone, or stainless steel. It initially has an elongated rectangular flat shape. The strip is flexible so that it can be wound inside a support as illustrated in the figure 3 .

[0033] According to the embodiment shown in the figure 2 The ferromagnetic elements 4 are identical to each other. In this case, they are rectangular parallelepipeds. They are arranged at constant intervals along the longitudinal direction of the strip 2. According to this embodiment, the ferromagnetic elements are arranged in unit groups along the strip. However, it is possible to arrange the ferromagnetic elements in groups of at least two elements, the number of which is a matter of arbitrary choice by a person skilled in the art. Thus, two elements 4 can be close to each other, separated from the next group of two elements 4, and so on.

[0034] The spacers 6 are arranged here alternately with the ferromagnetic elements 4. Advantageously, a spacer is placed between each ferromagnetic element and vice versa.

[0035] In the presence of groups of at least two ferromagnetic elements, it is also possible to place at least one spacer in each group of ferromagnetic elements and / or between the groups.

[0036] The ferromagnetic elements and / or spacers are all arranged here on the same face 7 of the strip. However, it can be assumed that they are distributed on the two opposite faces 7 and 9 of the strip.

[0037] There figure 1 This illustrates that the strip is not necessarily adapted to a specific type of ferromagnetic element 4 and / or spacer 6. Indeed, it is possible to attach any type of ferromagnetic element and / or spacer to the flexible strip according to the invention. In other words, the strip is not designed exclusively for one type of ferromagnetic element and / or one type of spacer.

[0038] The strip is equipped with fastening means. These fastening means are adhesives, in the form of glue, present on both sides 7 and 9.

[0039] On the band of the figure 2 ferromagnetic elements do not yet form permanent magnets.

[0040] THE figures 3 et 4 represent an electric motor component 8, such as a stator or rotor, equipped with an assembly 1, namely a flexible band 2 and ferromagnetic elements 4 attached to the band 2.

[0041] The ferromagnetic elements are therefore attached to the strip, which is itself fixed to a support, in this case a rotor or a stator. The rotor or stator has a cylindrical shape with a circular cross-section in a plane perpendicular to the axis 10 of the cylinder.

[0042] In this embodiment of an electric motor component 8, the flexible band is fixed inside the component on an inner face 11 of the component. It extends along the circumference of this face 11, adapting to it thanks to its flexibility. It thus forms a turn around the axis 10. Its face 9 also makes surface contact with the inner face 11 of the rotor or stator.

[0043] Here, component 8 is a rotary electric motor component 12 due to the circumferential arrangement of the strip on the inner face of component 8. Of course, the electric motor can be linear. In this case, the stator and rotor are planar, in which case the flexible strip to which ferromagnetic elements and / or spacers are attached is fixed in a plane.

[0044] The electric motor 12 can equip a vehicle wheel braking system 14, as schematically represented in the figure 5 . In this braking system 14, brakes 16 are actuated by means of the energy supplied by the electric motor 12.

[0045] One manufacturing process for the electric motor 12 is, for example, as follows.

[0046] According to this process, assembly 1 is initially outside its final support. The operator therefore has complete freedom to carry out the following steps.

[0047] With the strip 2 laid flat on a work surface, the operator positions the ferromagnetic elements 4 on the strip 2 according to the final geometry of the strip on its final support, for example, the frame of a rotor or stator. If the support is a rotor or stator, the ferromagnetic elements, once magnetized, will react to the magnetic field created by the electric current flowing through the motor winding. They must therefore be positioned as precisely as possible. This precise positioning can, for example, consist of positioning groups of ferromagnetic elements at constant intervals along the flexible strip. It is also possible to position the ferromagnetic elements according to a repeating pattern, either at constant or variable intervals, along the strip. For example, a group of two ferromagnetic elements can follow a group of three ferromagnetic elements.In other words, groups of ferromagnetic elements do not necessarily contain the same number of ferromagnetic elements. Ferromagnetic elements can also be oriented with opposite polarities within the same group or alternately from one group to another.

[0048] The operator fixes one or more spacers 6 between each group of ferromagnetic elements 4, unitary or not.

[0049] Once the positioning step is complete, the operator attaches the ferromagnetic elements 4 to the flexible strip 2. This can be done by crimping the ferromagnetic elements 4. Alternatively, adhesives can be used to attach the ferromagnetic elements to the strip. The adhesive is flexible and heat-cures at a temperature at which it is activated, ensuring a durable bond between the ferromagnetic elements 4 and the flexible strip 2. Therefore, as the temperature increases, the heat absorbed by the adhesive strengthens the bond between the ferromagnetic elements 4 and the flexible strip 2. An exposure temperature above 70°C, 100°C, or 150°C is sufficient to secure the elements 4 to the strip 2. However, the exposure temperature must not exceed the demagnetization temperature of the ferromagnetic elements 4, also known as the Curie temperature of the material.The adhesive used is therefore chosen accordingly. Indeed, at this specific temperature, a ferromagnetic material, such as that of elements 4, loses its permanent magnetization. Thus, as long as the heat emitted by the motor does not cause the Curie temperature of elements 4 to be reached, their attachment to the flexible strip 2, thanks to the polymerizable adhesive, is preserved by the heat from the motor. Another advantage of using a flexible adhesive is the damping of vibrations and noise emitted by the motor's operation.

[0050] The spacers are also attached to the flexible band 2. To do this, it uses the same fastening methods used for the ferromagnetic elements.

[0051] At this stage of the process, the flexible tape 2 is fitted with ferromagnetic elements 4 and spacers 6 fixed on one or both of its faces. In this state, the tape can be in the form of a roll or a reel.

[0052] The strip is suitable for direct assembly onto a support: if necessary, the operator has adapted the length of the flexible strip 2 to the final support to which it will be fixed. At the figure 1 , we have schematically illustrated the fact that the operator cuts a portion of flexible strip 2 onto which ferromagnetic elements 4 and spacers 6 are fixed.

[0053] The operator now installs and secures assembly 1 to a rotor or stator of the electric motor 12. Adhesives can be used to attach the flexible strip 2 to the rotor or stator. For example, one or both sides of the strip may be adhesive, in which case it is sufficient to apply one side to a receiving part of the rotor or stator to attach the flexible strip 2 to the rotor or stator.

[0054] With the flexible strip now attached to the stator or rotor, the operator magnetizes the ferromagnetic elements so that they become permanent magnets. After this step, the ferromagnetic elements are capable of being driven by a magnetic field and can therefore convert electrical energy into mechanical energy.

[0055] This manufacturing process for motor 12 may include a step of magnetically shielding the motor. Such magnetic shielding can be achieved using a material or assembly of materials exhibiting high magnetic susceptibility and the lowest possible coercive field. Indeed, magnetic susceptibility describes the intensity of the material's response to magnetic excitation. A material with high magnetic susceptibility will therefore tend to concentrate magnetic field lines within itself, thus preventing them from spreading beyond its boundaries. On the other hand, it is important that the coercive field of the chosen material be as low as possible, in order to avoid hysteresis effects and, in particular, to ensure that the magnetic shielding is effective even at the weakest fields.Thus, eligible materials include, for example, pure iron, soft iron, cobalt, nickel, copper or metal assemblies including metals chosen from iron, nickel, molybdenum, copper, silicon etc... As an example, the following alloys marketed by the company Aperam under the name Mumetal (Ni 80 FeMo 5 ), SuperMumetal (Ni 80 FeMo 5 ), Cryophy (Ni 81 FeMo 5 ), Supra50 (FeNi 48 ) or Supra36 (FeNi 36 ) are eligible.

[0056] In practice, the shielding process includes an isolation step for the device to be protected, in this case the electric motor 12, within an enclosure formed by the shielding material. This enclosure constitutes the shielding of the device. It can have many shapes or geometries. However, spherical, cylindrical, or rounded shapes with sharp edges are often preferred. The thickness of the shielding and the number of successive layers forming it are also parameters chosen according to the circumstances. Such shielding makes it possible to isolate the ferromagnetic elements 4 from the surrounding fields and / or to prevent the motor from disturbing the surrounding magnetic field with its own. Since the ferromagnetic elements 4 have a magnetization specifically determined according to the motor's requirements and expected performance, the shielding helps to preserve the motor's performance or even prevent any motor malfunction.

[0057] This manufacturing process for the 12 engine and the steps that compose it offer several advantages.

[0058] First, as explained above, the steps of positioning the ferromagnetic elements and spacers on the belt and attaching the belt to its support can be separated. This separation offers greater comfort for the operator. They can work on a work surface, rather than directly on the rotor or stator housing, which often has a geometry that is unfavorable for handling. Furthermore, since the ferromagnetic elements are not yet magnetized, they are easier to handle.

[0059] The process of attaching the ferromagnetic elements and spacers to the belt is also easier thanks to this method. Many more fastening methods can be used since the operator is not limited by the size of the casing, as can be the case with current technologies.

[0060] The ability to separate the positioning and fastening steps allows multiple operators to be involved during the manufacturing of the electric motor. It is also possible to store flexible strips ready for direct assembly for future use. This process therefore offers greater flexibility in the logistical management of electric motor manufacturing plants and, ultimately, of braking systems. Furthermore, the bonding methods are more easily adapted to all types of materials that can be used for the flexible strip, namely: plastic, resin, silicone, or metal, such as stainless steel.

[0061] The invention is not limited to the embodiments shown, and other embodiments will be obvious to those skilled in the art. In particular, it is possible to adapt the invention to any rotating machine, for example, an alternator. List of references used:

[0062] 1: assembly 2: flexible band 4: ferromagnetic elements 6: spacer 7: one face 9: the other face 10: shaft 11: inner face of the rotor or stator 12: electric motor 14: braking system 16: brake

Claims

1. An assembly (1) comprising: - a flexible strip (2) having a first face and a second face, the strip being provided with at least one adhesive, and - ferromagnetic elements (4) secured to one of said faces of the strip (2) by means of the adhesive and separated from one another by at least one spacer (6), the assembly being configured such that at least part of one of said faces of the strip is capable of being directly bonded to a substrate by means of adhesive, the strip (2) being designed to accommodate different types of ferromagnetic elements and / or different types of spacers and made from a material selected from the following list: plastic, resin, silicone, stainless steel, characterised in that the adhesive is a flexible adhesive polymerisable at a temperature above 70°.

2. Assembly according to the preceding claim, in which the ferromagnetic elements (4) are arranged at a constant pitch along the strip (2).

3. An assembly according to one of claims 1 to 2, wherein the ferromagnetic elements (4) form groups of at least two ferromagnetic elements, these groups being arranged at a constant pitch along the strip (2).

4. Assembly according to one of the preceding claims, in which the ferromagnetic elements form permanent magnets.

5. A braking system (14) equipped with an electric motor (12), characterised in that it comprises: - a component (8) of the electric motor (12), such as a stator or a rotor, - an assembly as defined in any of claims 1 to 4.

6. A method of manufacturing an electric motor comprising the steps of: - ferromagnetic elements (4), separated from one another by at least one spacer (6), are fixed to one side of a flexible strip (2) - the strip (2) having a first side and a second side - using an adhesive, then - the strip (2) is mounted on a stator or rotor of the electric motor by means of bonding, characterised in that the adhesive is a flexible adhesive polymerisable at a temperature above 70°C, the strip (2) being designed to accommodate different types of ferromagnetic elements and / or different types of spacers and being made of a material selected from the following list : plastic, resin, silicone, stainless steel.

7. A method according to the preceding claim, comprising a further step in which the ferromagnetic elements (4) are magnetised so that they become permanent magnets.

8. A method according to one of claims 6 or 7, wherein the fixing step comprises crimping.

9. A method according to at least one of claims 6 or 7, wherein at least one spacer (6) is fixed between some of the ferromagnetic elements (4).

10. A method of manufacturing a braking system (14) comprising a method of manufacturing an electric motor (12) according to any one of claims 6 to 9.