Magnetic locking and position measuring device for a rotating member

Abstract

The invention relates to a magnetic braking device (1) for an electric motor of a rotating member comprising at least: a rotor-forming magnet, of cylindrical shape extending along an axis of rotation (AA'), the wall of the cylinder comprising at least one north part (2) and at least one south part (4) forming at least one pair of poles, each part forming a half-cylinder and being extended towards the inside and / or the outside of the rotor, to form a detection part; a magnetic feedback stator (6) making it possible to create a torque for holding the magnetized rotor in a fixed position of said rotating member. Figure 1A

Description

Title of the invention: Magnetic locking and position measuring device for a rotating member

[0001] TECHNICAL FIELD AND STATE OF THE PRIOR ART

[0002] The field of the invention is that of locking elements for organs rotating, for example shutters such as electrified roller shutters.

[0003] If we consider for example the roller shutters, they are in the form of tubes and comprise an assembly of a motor, a reducer and a brake.

[0004] For these rotating members, the problem arises of having a braking system, preferably frictionless, ensuring the braking of the system as well as maintaining said member in position when the engine is stopped. But there is also the problem of providing a position indication or detection of the rotation of the rotating member. Preferably, such a system is reliable, simple, economical and compact.

[0005] Indeed, we know of static braking systems using fixed or static magnets, with the help of which we cannot therefore count the revolutions or identify the position of the organ concerned.

[0006] We also know a system for counting revolutions using a magnetic rotor, but which requires the use of powerful magnets, heavily loaded with rare earths (for example Neodymium) with sufficient density to generate a magnetic field strong enough to reach the sensor and thus count the revolutions.

[0007] A centrifugal rotor system is also known which separates from a notched stator during rotation: but this magnetless brake solution is complex and requires the addition of other means, for example at the end of the moving part of the brake, to perform a position detection or revolution counting function. Description of the invention

[0008] The invention aims to remedy at least in part the drawbacks of the prior art.

[0009] It first concerns a magnetic brake, at least static, comprising at least two elements: - a rotor, provided with a magnetization system, for example a magnet, with at least one pair of poles; - a magnetic feedback stator to create a braking torque in combination with the magnetized rotor.

[0010] Such a brake also makes it possible to brake a component at low speed, at the end of its travel. It can therefore exert dynamic braking, but over a small, low speed range close to stopping.

[0011] The invention makes it possible to limit the number of components by ensuring several functions with the same magnet, which also contributes to the compactness of the system.

[0012] It also allows the use of a magnet at least partly made of ferrite or a plastomagnet, for example of the NdFeB type, with a low density of rare earths; such solutions are more economical than rare earths and have a much more limited environmental impact than these.

[0013] A rotor according to the invention comprises a magnet comprising one or more alternation(s) of north and south polarities which interact with the stator to form the electric brake.

[0014] The invention makes it possible to use static magnetic braking technology. It allows the implementation of an economical form of magnet, for example made of ferrite, and ensuring static braking of the motor, and therefore its holding in position when stopped; possibly, the same magnetization system makes it possible to provide a position measurement using a probe, for example a Hall effect probe, which can be located at a fixed diameter of the magnet.

[0015] The invention makes it possible to minimize the mass of the magnet (with the same magnet, it is possible to perform the static braking function and rotation detection) and to use injected magnet technology to have a rotor shape fulfilling a brake function and possibly a position sensor function for controlling the motor.

[0016] According to the invention, the generator of the magnet is “L” shaped: the magnet is for example extended towards the inside and / or the outside of the rotor, to allow the formation of a detection part which, in cooperation with a sensor for example of the Hall effect type, will allow the rotation of the rotor to be detected.

[0017] In the case of the “L” shaped magnet generator, the side of the magnet facing the stator (the “large bar” of the “L”) is useful for braking and the other side of the magnet (the “small bar” of the “L”) is useful for measuring the position. This “L” shape can be made, for example, by a plastic injection process. Advantageously, no magnetized material is used in the areas that are not functional; in other words, the material is only present where it is necessary. This rotor shape fulfills a magnetic brake function, at least static, and possibly a position sensor function, for example for controlling the motor.

[0018] The stator may be laminated or be a solid, non-laminated stator.

[0019] The invention also relates to a magnetic braking device for an electric motor of a rotating member or a method for magnetic braking, at least static, of an electric motor of a rotating member, this device or this method implementing a device according to the invention. The magnetic feedback stator makes it possible to create a torque for holding the magnetized rotor in a fixed position of said rotating member.

[0020] The invention also relates to a method for magnetic braking, at least static, of an electric motor of a rotary member, for example using a device according to the invention, this method comprising:

[0021] - the rotation of a magnet, of cylindrical shape extending along an axis of rotation (AA'), the cylinder wall comprising at least one north portion and at least one south portion forming at least one pair of poles, each portion forming a half-cylinder and being extended towards the inside and / or outside of the rotor, to form a detection portion;

[0022] - the formation, using a magnetic looping stator, of a couple of maintaining the magnetic rotor in a fixed position of said rotating member.

[0023] According to an exemplary embodiment, said rotary member is or comprises a rolling shutter. Brief description of the drawings

[0024] Other aspects, aims, advantages and characteristics of the invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the appended drawings in which: • [Fig.lA] and [Fig.lB] are schematic views of an example of a brake according to the invention; • [Fig.2A] and [Fig.2B] represent 2 views of an example of a rotor for a brake according to the invention; • [Fig.3A] and [Fig.3B] are views of another example of a brake according to the invention. • [Fig.4A] and [Fig.4B] represent various views of another example of a rotor for a brake according to the invention; • [Fig.5] represents an example of support for a device according to the invention.

[0025] DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0026] In the figures and in the remainder of the description, the same references represent identical or similar elements. In addition, the different elements are not shown to scale so as to enhance the clarity of the figures. Furthermore, the different embodiments and variants are not mutually exclusive and may be combined with each other. Unless otherwise stated, the terms "substantially", "approximately", "in the order of" mean to within 10%. Furthermore, the terms "between ... and..." and equivalents mean that the limits are included, unless otherwise stated.

[0027] The invention relates in particular to a brake 1, an example of which is illustrated in FIGS. 1A and 1B: a rotor (with axis of rotation AA') of cylindrical shape comprises a magnet having a part 2 of north polarity and a part 4 of south polarity, these polarities being diametrically opposed to each other; these different parts 2, 4 can interact with a magnetic feedback stator 6 (represented in [Fig. 1B]) to form an electric brake. In [Fig. 1B], the reference 8 designates a support for coupling the magnet to a motor. The brake 1 can be coupled to a motor, for example of the brush type or of the BLDC type. This motor can for example be arranged in a tubular motor, around which a rotating member is wound, for example a roller shutter, or a blind or a mosquito net in the form of a blind, or a sunshade, or a garage door, or a gate. The rotating organ in question has an axis arranged horizontally when in use.

[0028] Between the motor and the output shaft of the tubular motor there may be a reducer or torque and / or speed reduction stage, the magnet therefore being driven at high speed (for example speed > 100 rpm) by the motor and therefore being able to be advantageously used for measuring or detecting position or rotation, since the higher speed allows greater reliability of this detection.

[0029] The rotor of a brake 1 according to the invention is therefore advantageously fixed relative to the rotor of a geared motor (before reduction, therefore at high speed), the stator of the brake being advantageously fixed relative to the stator of the geared motor. This stator of the geared motor is preferably fixed relative to the frame of the mechanism (for example of a roller shutter).

[0030] The invention makes it possible to produce a passive brake, i.e. one for which there is no need to use an exciter coil to activate the braking and position-holding function. The position-holding function is obtained by the natural rest position of the magnets facing the stator 6, this position being maintained by attraction by the magnet. There is therefore a point of equilibrium due to the magnetic notching. The braking function is obtained by the passage of the magnetic field of the magnet in the stator which, by its relative permeability, creates a viscous braking torque adjustable by the stacking of sheet(s) of the stator 6 and / or the thickness of each sheet of the stator. The iron losses of the stator can be broken down into 3 parts according to the Bertotti model:

[0031] [Math.l] Pfer = W ( B m *f ) ° 2 + k. ( V / )

[0032] Where:

[0033] k} is the hysteresis loss coefficient also called magnetic dry friction;

[0034] k2 is the eddy current loss coefficient also called magnetic viscous friction;

[0035] k3 is the excess loss coefficient (it can be assumed to be zero because the frequency domain is not high enough for this term to be predominant compared to hysteresis and eddy current losses). This coefficient is only taken into account for frequencies of the order of Megahertz (MHz), but here the frequency is "1 MHz.

[0036] Hysteresis losses are due to the geometry of the motor, eddy current losses involve the thickness of the stator laminations which allows the viscous magnetic friction to be adjusted (it is this thickness of the laminations which allows the viscous friction to be adjusted) and therefore the frequency braking of the magnetic brake.

[0037] Each magnetic looping sheet is part of the stator 6; for example, housings are provided in a static part, fixed to the stator of the motor, to accommodate one or more stator sheets. There are as many such housings as there are poles on the magnet and the different sheets 6b 62 are located diametrically opposite each other.

[0038] In the context of the present invention, it is sought to obtain a maintenance in the stopped position of the rotor, after complete rotation, in one direction or another, of a rotating member (for example after complete winding or complete unwinding of an electric shutter) and not a braking of the latter during its entire stroke. A device according to the present invention therefore preferably uses a solid, non-laminated stator, the braking of which (during the rotation of the stator) is negligible in view of the system in which the magnetic brake is integrated. In addition, in the case where a plasto-magnet is used for the magnet 1, the stator is not magnetically saturated (it is thick in its radius compared to the level of magnetic field emitted by the magnets); therefore the coefficient Bm of the Bertotti equation is then low, which further reduces the magnetic braking.

[0039] Each part 2, 4 of the magnet forms a half-cylinder. According to one aspect of the invention, the active part of the magnet for dynamic braking and position holding (or static magnetic braking) is the part 12 (the “large bar” of the “L”) which is located under the magnetic looping sheet(s) 6.

[0040] The magnet forms a cylinder 14; as shown in figures 2A - 2B, each of its parts 2, 4 can extend towards the inside of the rotor, in the direction of the axis AA', preferably at one of the ends of the cylinder 14, to form a part in the form of a crown or a ring or a disc 16 comprising a part 161 of north polarity and a part 162 of south polarity and whose center is on axis AA'. This part is flat, that is to say of extension, along the axis AA', small compared to its external diameter or its dimension (measured in a plane perpendicular to the axis AA') the widest. The magnet therefore has an "L" shaped generator, the large bar of which faces the stator and the small bar allows the detection of the rotation or the position, the small bar having its free end oriented inwards (in the direction of the axis AA'). Each of these parts 161, 162 is flat, arranged at the end of the large bar of the "L" and extends substantially perpendicular to the axis AA', in the direction of the latter. These parts will allow, in cooperation with a sensor 20 (represented in figures 1A and 1B), for example of the Hall effect type, to measure the rotational position of the rotor.The data resulting from this measurement can be processed by an electronic control card (PCBA) and make it possible to know the position of the rotor axis and therefore to control an electric motor coupled to the static magnetic brake by adjusting its power supply according to this measurement.

[0041] In figures 1A - 2B, the sensor 20 is located at a distance from the axis AA' of the rotor, less than the external size or the diameter of the latter or of the parts 2, 4.

[0042] Another embodiment is illustrated in figures 3A - 3B and 4A - 4B, in which the sensor 20 is located at a distance from the axis AA' of the rotor which is greater than the external size or the diameter of the latter or of the parts 2, 4. The use of the data can be the same as that described above.

[0043] Figures 4A - 4B show various views of the rotor, in which each part 2, 4 extends outward from the rotor, to form a crown or ring 17 comprising a part 171 of north polarity and a part 172 of south polarity and whose center is on the axis AA'. The magnet therefore has an "L" shaped generator, the large bar of which faces the stator and the small bar allows the detection of rotation or position, but the small bar has its free end oriented outward (in the opposite direction to the axis AA'). Here again:

[0044] - each of these parts 161, 162 is flat and extends substantially perpendicular to the axis AA', this time at least in the opposite direction to it, towards the outside of the cylinder;

[0045] - these parts will allow, in cooperation with a sensor 20 (represented in figures 3A and 3B), for example of the Hall effect type, to measure the rotational position of the rotor. In figures 3A - 4B, the sensor 20 is therefore located at a distance from the axis AA' of the rotor, greater than the external size or the diameter of the latter or of the parts 2, 4.

[0046] Preferably, a magnet implemented within the framework of the invention is at least partly made of ferrite or is a plastomagnet, for example of the NdFeB type, with a low density of rare earths; such solutions are more economical than rare earths and have a much more limited environmental impact than these. For example, it is possible to produce a magnet containing neodymium injected with plastic: the Nd is then much less dense (for example we have a density lower than 5 g / cm3) than in purely neodymium magnets (which have a density of around 7.5 g / cm3). A plastic injection technique is well suited to the production of a magnet with an “L” shaped generator. The loss of material is then minimized.

[0047] In an assembly according to the invention combining a brake and a rotation or position sensor, the sensor is fixed relative to the stator of the brake and their position can be adjusted in order to ensure the reliability of the measurement. For this, a part made of non-ferrous material so as not to interfere with the different magnetic fields, for example plastic, can ensure the respective position of these 2 elements and their relative maintenance.

[0048] The magnetic notching of the brake, i.e. the static restoring force of the magnets on the stator, makes it possible to hold a rotating member in position, for example a roller shutter apron via its winding shaft: for example, a notching of 0.000N.m on the brake for a reduction ratio of 220 gives a holding torque at the end of the shaft of 100N.m (assuming an efficiency of 81% for the reduction gear).

[0049] [Fig. 5] represents a support 30 for a device according to the invention: the parts 2, 4 of the rotor and the stator 6 are recognized. The support here comprises 2 arms 32, 34 each provided with a hole 33, 35 for fixing on a motor.

[0050] The invention therefore relates in particular to a magnetic braking device for an electric motor of a rotating member comprising at least: - a rotor-forming magnet, cylindrical in shape extending along an axis of rotation (AA'), the wall of the cylinder comprising at least one north part 2 and at least one south part 4 forming at least one pair of poles, each part forming a half-cylinder and being extended towards the inside and / or the outside of the rotor, to form a detection part; - a magnetic relooping stator 6 making it possible to create a torque for holding the magnetized rotor in a fixed position of said rotating member.

[0051] A device according to the invention further comprising a sensor, to enable, in interaction with the detection part, the rotation of the rotor to be detected, may further comprise processing means for calculating or estimating the position of the rotor.

[0052] In a device according to the invention, the magnetic looping stator may comprise at least 2 parts arranged in housings of the stator.

[0053] The invention also relates to an electric motor comprising a rotor, a stator and a magnetic braking device according to the invention, the magnet forming the rotor of this magnetic braking device being linked to the rotor of the electric motor.

[0054] The invention also relates to an electrified rolling member, comprising a rolling member, for example a roller shutter or a blind or a mosquito net in the form of a blind, or a sunshade, or a garage door, or a gate, and an electric motor according to the invention.

Claims

Claims

1. Magnetic braking device (1) for an electric motor of a rotating member comprising at least: - a magnet forming a rotor, of cylindrical shape extending along an axis of rotation (AA'), the wall of the cylinder comprising at least one north part (2) and at least one south part (4) forming at least one pair of poles, each part forming a half-cylinder and being extended towards the inside and / or the outside of the rotor, to form a detection part; - a magnetic feedback stator (6) making it possible to create a torque for holding the magnetized rotor in a fixed position of said rotating member.

2. Device according to claim 1, each part of the magnet extending, in a direction perpendicular to the axis of rotation (AA'), to form a crown or a ring or a disc (16, 17) comprising at least one part (161, 171) of north polarity and at least one part (162, 172) of south polarity and whose center is on the axis of rotation (AA').

3. Device according to claim 1 or 2, further comprising a sensor (20) for example of the Hall effect type, to allow, in interaction with the detection part, to detect the rotation of the rotor.

4. Device according to claim 3, further comprising processing means for calculating or estimating the position of the rotor.

5. Device according to one of claims 1 to 4, the magnetic looping stator (6) comprising at least 2 parts arranged in housings of the stator.

6. Device according to one of claims 1 to 5, each part of the rotor forming a half-cylinder being extended towards the inside and / or the outside of the rotor to form a detection part at one end of the magnet, along said axis of rotation (AA').

7. Device according to one of claims 1 to 6, the rotor-forming magnet being at least partly made of ferrite.

8. Device according to one of claims 1 to 6, the rotor-forming magnet comprising or being a plastomagnet, for example of the NdFeB type, with a low density of rare earths.

9. Device according to one of claims 1 to 8, the stator being laminated or being a solid, non-laminated stator.

10. Electric motor comprising a rotor, a stator and a magnetic braking device (1) according to one of claims 1 to 9, the magnet forming the rotor of this magnetic braking device being linked to the rotor of the electric motor.

11. An electric motor according to claim 10, arranged in a tubular motor.

12. An electric motor according to claim 11, a reducer being arranged between the electric motor and the tubular motor.

13. Electrified rolling member, comprising a rolling member, for example a roller shutter or a blind or a mosquito net in the form of a blind, or a sunshade, or a garage door, or a gate, and an electric motor according to one of claims 10 to 19

14. IZr. Method for static magnetic braking of an electric motor of a rotating member comprising: - the rotation of a magnet, of cylindrical shape extending along an axis of rotation (AA'), the wall of the cylinder comprising at least one north part (2) and at least one south part (4) forming at least one pair of poles, each part forming a half-cylinder and being extended towards the inside and / or the outside of the rotor, to form a detection part; - the formation, using a magnetic feedback stator (6), of a torque for holding the magnetized rotor in a fixed position of said rotating member.

15. A method according to claim 14, said rotating member comprising a roller shutter or a blind or a mosquito net in the form of a blind, or a sunshade, or a garage door, or a gate, said rotating member having an axis of rotation arranged horizontally.

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