SELF-CONTROLLED SYNCHRONOUS TURNIP MACHINE WITH BRAKE DEVICE

Description

[0001] The present invention relates to a self-piloted synchronous rotating machine of the brushless motor type equipped with a rotor braking and immobilization device.

[0002] These motors typically consist of a fixed stator equipped with coils operating as electromagnets, generating stator magnetic fields of varying amplitude and phase, depending on the current supplied to the coil. This supply is, in practice, controlled by the position of the rotor's permanent magnets, hence the self-control, and therefore by the orientation of the rotor magnetic fields. Appropriate sensors (for example, Hall effect sensors) constantly detect the precise angular position of the rotor in order to deduce the phase to be given to the stator magnetic fields by the supply currents (this is generally a three-phase supply). The stator coils are, in fact, energized in such a way as to continuously create, on the periphery of the rotor, magnetic fields that are out of phase, for example, in quadrature, with the rotor magnetic fields.The rotor, whose magnetic fields constantly strive to align with the stator magnetic fields, is then driven to rotate, according to the classic operation of rotating electrical machines. The phase quadrature of the magnetic fields ensures the creation of maximum motor torque.

[0003] The operating speed of the brushless motor is regulated by modulating the current in the stator windings. An increase in this current speeds up the motor's rotational speed, while a decrease has the opposite effect. Modulating the supply current also allows for the management of motor torque. Control is achieved through electronic control systems that, in simplified terms, manage both the feedback signals from sensors detecting the rotor's position and the shape and intensity of the supply currents to the stator windings.

[0004] The issue of braking these brushless motors is the same as for DC motors with commutators, since in the absence of power, such a motor generally has only limited braking capacity, far below the actual requirement. This "natural" braking results in practice from the "cogging torque." When the stator windings cease to be energized, the motor is also braked by the mechanical reduction gear located on the transmission shaft coupled to the rotor, which generates a resistive torque in addition to the cogging torque. This type of uncontrolled natural braking is, however, unsatisfactory and, above all, insufficient in many applications for these motors.

[0005] Similar self-piloted synchronous rotating electric machines of the brushless motor type are described in particular in documents US2005 / 184691 A1, US4251758 A and EP0783072 A1.

[0006] The present invention relates to a self-piloted synchronous rotating electric machine of the brushless type, as defined in independent claim 1.

[0007] Thus, in a preferred application of the invention to the motorization of roller shutters, in which the motors in most cases include at least one reduction gear, and for which braking without necessarily resulting in locking can be implemented, the braking torque to be applied is variable, potentially reaching up to twice the declared motor torque, the maximum descent speed of the roller shutter being on the order of 150 mm / s. A suitable braking device must meet the resulting constraints.

[0008] One of the objectives of the present invention is to avoid linking the braking function to the control and power supply of the stator coils, and to provide a braking and immobilization device that is simple to implement and effective for immobilizing the rotor. In the rotating machine configuration of the invention, braking is indeed controlled electronically, but locking is independent of it. In the event of slippage, it is also possible to limit the descent of the load by short-circuiting the windings in order to create a counter-EMF. The goal, however, remains to immobilize the motor shaft in the absence of electrical supply currents.

[0009] To achieve these objectives, the braking and immobilizing device of the synchronous rotating machine of the invention, which includes at least one permanent magnet mounted fixed relative to the stator in the vicinity of one end of the rotor, is such that the permanent magnets equipping the periphery of the rotor (20) have extensions protruding from the stator in a direction parallel to the axis of rotation of the rotor, in the vicinity of which is fixed at least one permanent magnet of the braking and immobilizing device, each magnet of the braking and immobilizing device being housed in a casing fixed against a front face of a magnetic pole yoke of the stator surrounding the stator coils.

[0010] This simple solution generates a static torque that helps to load the rotor in predetermined positions. It plays a significant role in braking when the stator coils are not energized, i.e., when the motor is not running. When energized, the braking and locking device of the invention is not detrimental because the permanent magnet is positioned such that the average magnetic field it generates in the structure is zero.

[0011] Moreover, this is a solution which can present a very interesting advantage insofar as, combined with a structural feature of the rotating machine of the invention, it allows the simultaneous implementation of two functions.

[0012] This particular configuration in which the end portions of the rotor magnets come out of the stator assembly imposes a very localized positioning of the magnet(s) of the braking and immobilizing device.

[0013] But it also optimizes the overall operation of the motor because, in addition to the braking function that is the subject of the invention, this structure facilitates the detection of the rotor's angular position by Hall effect sensors, which benefit from the extension of the ferrites. It is clear that, to function optimally, these sensors must be positioned close to the magnets they are designed to detect, which is obviously the case with this solution.

[0014] According to a first possibility, assuming that said extensions are polarized in a radial direction, the polarization of the adjacent magnets around the rotor always being reversed, at least one magnet of the braking and immobilizing device is placed, in a radial direction, opposite the extensions protruding from the stator.

[0015] According to a second possibility, if the said extensions are polarized in an axial direction, the polarization of two adjacent magnets on the periphery also always being reversed, at least one magnet of the braking and immobilizing device is placed, in an axial direction, opposite the ends of the extensions protruding from the stator.

[0016] Under this same assumption, where the extensions are polarized in an axial direction, and the polarization of two adjacent magnets on the rotor's periphery is always reversed, at least one sensor, for example a Hall effect sensor, can be placed on an electronic board positioned near and opposite the ends of the extensions protruding from the stator. This doubly benefits the aforementioned specific structure in which axial extensions of the magnets protrude from the stator.

[0017] A simple structure allowing for precise positioning of the permanent magnet(s) of the braking and immobilizing device consists, as previously mentioned, of housing each magnet, if there are several, in a casing fixed against a magnetic pole piece of the stator surrounding the stator coils. This support allows for precise positioning in an axial direction, but the attachment to this pole piece also offers the possibility of fine positioning in a radial direction.

[0018] To keep things simple, the magnet(s) of this braking and immobilizing device can take the form of a disc, a shape readily available almost everywhere at very low cost.

[0019] In practice, the braking device of the invention preferably consists of a single permanent magnet, as will be the case in most scenarios. Similarly, although both configurations of rotating machines, with an internal rotor (enclosed within the stator) or an external rotor (enclosing the stator), can exist and function in the same way with a braking and locking device as described above, the variant with an internal rotor, located inside the stator, is preferably used.

[0020] The invention also relates to the use of a rotating electric machine as described above for driving a motorized roller shutter hub. This is a preferred application in which the braking device used functions very satisfactorily.

[0021] The invention will now be described in more detail, with reference to the attached figures, for which: there figure 1 is an exploded perspective view of the stator of a self-piloted synchronous motor equipped with a braking and immobilizing device according to the invention; the figure 2 shows a partial view, also in perspective, of said stator assembled and fitted with the braking and immobilizing device; and the figure 3 represents a perspective view of a complete synchronous motor, that is to say equipped with its rotor and an unassembled closing flange and showing the braking and immobilizing device of the invention.

[0022] With reference to the figure 1 The stator of the self-piloted synchronous motor of the invention comprises a cylindrical peripheral magnetic yoke (1) and stator coils (2), each wound on a frame (3). These coils (2) and their frames (3) are positioned around elongated axial reliefs (4) formed by peripheral teeth, machined into sheets whose stacking forms a laminated stator pole ring (5). One of these coils (2) is shown at a distance from the stator ring (5), and the unit it forms with its frame (3) is clearly visible. When positioned, the coils (2) are effectively placed between said stator ring (5) and the cylindrical, laminated peripheral magnetic yoke (1). The free radial end of the elongated reliefs (4), protruding from the carcasses (3) of the coils (2) when the latter are positioned, is also used for the positioning and fixing of the stator ring (5) in the peripheral cylinder head (1).

[0023] The end of said stator ring (5) appearing to the right of the figure 1 It has mounting pins (6) and connection pins (6') distributed around its periphery. The pins (6) are used, in particular, to position the board (7) which includes an electronic connector (8), while the connection pins (6') with a conductive end are intended for connecting the coils (2), thus forming three groups of coils powered by the three phases of a three-phase current. This electronic board (7) also includes the rotor position sensors, for example, Hall effect sensors.

[0024] The permanent magnet (10), in this case in the form of a pellet, which is by no means a limiting shape, is housed in a casing (11) fixed to the stator, as shown in figure 2 In this position of the housing (11), the permanent magnet (10) is located – relative to the other components – as shown in the representation of the figure 3 , which illustrates a possible variant: it is placed radially with respect to the rotor (20) which is present in this figure. This rotor (20) is also made of stacked sheets, and it is essentially not visible in the figure (3) than through its transmission shaft (21) and its peripheral permanent magnets (22). In the configuration shown, the latter extend axially beyond the stator casing, so that the permanent magnet (10) of the braking and locking device can be positioned, within its housing (11), radially opposite the protruding end portions of said permanent magnets (22) covering the periphery of the laminated pole piece of the rotor (20). The sensors located on the board (7) are themselves very close to the protruding end portions of the magnets (22), thus ensuring optimal operation of the rotor position detection necessary for the self-control of this type of rotating machine. The existence of these extensions at the ends of the magnets (22) therefore cleverly allows two important functions to be performed separately.

[0025] The housing (11) is secured, by means of two tabs (12, 13), to the front face of the peripheral magnetic yoke (1) and, via a tab (14), in an opening (15) provided for this purpose in the closing flange (16) located at one of the axial ends of the motor. It is thus perfectly positioned and immobilized to maintain a constant position of the permanent magnet (10) relative to the rotor (20) and its magnets (22). The flange (16) also has other openings, including an opening (17) for the electronic connector (8) and openings (18) provided for the connection pins (6'). A bearing (19) surrounds a central opening (9) for the passage of the rotor shaft (21) (20).

[0026] The invention is of course not limited to the examples described and explained with reference to the figures, but it encompasses variants and versions which fall within the scope of the claims.

Claims

1. Self-propelled synchronous rotating electrical machine of the brushless motor type with a rotor (20), the periphery of which is covered with permanent magnets (22), and provided with a device for braking and immobilizing the rotor (20), the device for braking and immobilizing the rotor (20) comprising at least one permanent magnet (10) which is fixedly mounted with respect to the stator in the vicinity of one end of the rotor (20), characterized in that the permanent magnets (22) fitted on the periphery of the rotor (20) comprise extension pieces projecting from the stator in a direction parallel to the axis of rotation of the rotor (20), in the vicinity of which extension pieces at least one permanent magnet (10) of the device for braking and immobilizing the rotor (20) is fixed, each permanent magnet (10) of the device for braking and immobilizing the rotor being accommodated in a housing (11) fixed against a front face of a polar magnetic yoke (1) of the stator surrounding the stator coils (2).

2. Self-propelled synchronous rotating electrical machine of the brushless motor type according to the preceding claim, characterized in that said extension pieces are polarized in a radial direction, the polarization of two adjacent permanent magnets (22) on the periphery of the rotor (20) always being reversed, and in that at least one permanent magnet (10) of the device for braking and immobilizing the rotor (20) is placed, in a radial direction, opposite the extension pieces projecting from the stator in a direction parallel to the axis of rotation of the rotor (20).

3. Self-propelled synchronous rotating electrical machine of the brushless motor type according to claim 1, characterized in that said extension pieces projecting from the stator in a direction parallel to the axis of rotation of the rotor (20) are polarized in an axial direction, the polarization of two adjacent permanent magnets (22) on the periphery of the rotor (20) always being reversed, and in that at least one permanent magnet (10) of the device for braking and immobilizing the rotor (20) is placed, in an axial direction, opposite the ends of the extension pieces projecting from the stator in a direction parallel to the axis of rotation of the rotor (20).

4. Self-propelled synchronous rotating electrical machine of the brushless motor type according to either of claims 1 and 3, characterized in that said extension pieces projecting from the stator in a direction parallel to the axis of rotation of the rotor (20) are polarized in an axial direction, the polarization of two adjacent permanent magnets (22) on the periphery of the rotor (20) always being reversed, and in that at least one sensor, for example a Hall effect sensor, is placed on an electronic board (7) arranged in the vicinity of and facing the ends of the extension pieces projecting from the stator in a direction parallel to the axis of rotation of the rotor (20).

5. Self-propelled synchronous rotating electrical machine of the brushless motor type according to any of the preceding claims, characterized in that at least one permanent magnet (10) of the device braking and immobilizing the rotor is in the form of a disc.

6. Self-propelled synchronous rotating electrical machine of the brushless motor type according to any of the preceding claims, characterized in that the device for braking and immobilizing the rotor (20) comprises a single permanent magnet (10).

7. Self-propelled synchronous rotating electrical machine of the brushless motor type according to any of the preceding claims, characterized in that the rotor (20) is placed inside the stator.

8. Use of a self-propelled synchronous rotating electrical machine of the brushless motor type according to any of the preceding claims for driving a motorized roller shutter hub.