Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
  • H02K29/06—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with position sensing devices
  • H02K29/08—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with position sensing devices using magnetic effect devices, e.g. Hall-plates, magneto-resistors

Definitions

• the invention generally relates to polyphase rotary electric machines. More specifically, the invention relates to a polyphase rotary electric machine, suitable for use in a motor vehicle with an internal combustion engine on the one hand as an electric generator, and on the other hand as an electric motor in particular for starting the combustion engine.
• internal of the vehicle comprising a rotary shaft, a rotor integral in rotation with the shaft, a fixed polyphase stator surrounding the rotor, and magnetic means for monitoring the rotation of the rotor, these means comprising an annular target surrounding the shaft and integral in rotation with this shaft, and at least one fixed sensor disposed close to the target and cooperating with it.
• Machines of this type are known from the prior art, and in particular from patent application FR 2 807 231, which describes magnetic means the target of which is fixed to the pulley of the machine, the latter being itself integral in rotation of the shaft.
• Such a reversible machine is called an alternateo-starter.
• This target is rotated at high speed by the shaft and undergoes a significant centrifugal force.
• it is subjected to repeated cycles of acceleration and deceleration, depending on whether the vehicle starts or slows down.
• the present invention aims to overcome the above-mentioned defect.
• the machine of the invention is essentially characterized in that the target comprises an annular magnetic part and reinforcing means enveloping the magnetic part on a radially outer side.
• the target comprises an annular magnetic part and reinforcing means enveloping the magnetic part on a radially outer side.
• the air gap between the target and the sensor is well controlled.
• mounting is easy at the rear of the machine and good positioning accuracy of the sensor is obtained with respect to the target.
• the reinforcing means form a cylinder enveloping the annular magnetic part over the entire circumference of this part.
• the reinforcing means are made of a non-magnetic material for good looping of the magnetic flux.
• the reinforcing means consist of aluminum and / or austenitic steel and / or plastic and / or a woven or non-woven textile material.
• the reinforcement means can be: - force-fitted around the annular magnetic part, - hooped around the annular magnetic part, - glued around the annular magnetic part, magnetoformed around the annular magnetic part, thermoformed around the annular magnetic part, overmolded around the annular magnetic part.
• the annular magnetic part can be molded into the reinforcement means.
• the annular magnetic part is a plasto-magnet.
• the reinforcing means form a thin layer pressed against the magnetic part on a radially outer side.
• This thin layer is for example produced in the form of a strip or a film.
• the thin layer can be full.
• the thin layer may have openings.
• the magnetic part can fill the openings of the thin layer and can be flush with an outer side of the thin layer through the openings.
• the sensor is arranged radially outside the annular target, facing the latter.
• FIG. 1 is an axial sectional view d a polyphase rotary electrical machine according to the invention
• FIG. 2 is a side view of a target according to a first embodiment of the invention, the right half of the target being shown in section
• Figures 3 and 4 are enlarged views respectively of details III and IV of Figure 2
• - Figure 5 is a view equivalent to that of Figure 3, for a second embodiment of one invention
• - Figure 6 is an exploded view corresponding to FIG. 5.
• the rotary electrical machine shown in FIG. 1 is an alternator for a motor vehicle operating in a reversible manner.
• Such an alternator is called an alternator-starter and comprises a rotary shaft 1, a claw rotor 2 integral in rotation with the shaft 1, a fixed polyphase stator 3 surrounding the rotor 2, and magnetic means 4 for monitoring the rotation of the rotor 2.
• the axis of the shaft 1 defines the axis of rotation XX ′ of the electric machine, here of the polyphase type.
• the rotor 2 is integral with the shaft 1 and forms therewith a rotor assembly. This rotor 2 comprises two pole claw wheels 21 and an excitation coil 22 disposed between the pole wheels 21.
• Each pole wheel 21 has a flange extending substantially perpendicularly to the shaft 1, carrying teeth at its outer periphery. 'axial orientation directed to the flange of the other pole wheel.
• the teeth are offset circumferentially from one pole wheel to another and interpenetrate. They each have a trapezoidal shape.
• the flanges are each pierced with a central bore receiving the shaft 1, and are secured to this rotating shaft by ribs cooperating with grooves formed in the shaft 1.
• the stator 3 intended to be fixed on a fixed part of the vehicle, comprises meanwhile front and rear bearings 31 and 32, which are closed one on the other and fixed with each other here with tie rods referenced at 33 in FIG. 1 to form a casing, as well as a stator assembly 34 comprising a stator body carrying a set of stator windings.
• the stator assembly 34 surrounds the rotor 2 and comprises a body in the form of a sheet pack in which are formed a series of notches containing windings at the rate of at least one winding per phase which comprises 1 alternator-starter here of the three-phase type.
• the windings can be of the type with separate coils, with entangled coils or of the bar type, for example in the shape of a U as described in document WO 92/06527.
• the bearings 31 and 32 of hollow form are perforated for the circulation of air inside the machine of the compact type and with internal ventilation, the rotor 2 here carrying at each of its axial ends a fan referenced 23 in the figure 1. As a variant, only one fan 23 is provided.
• Each bearing 31, 32 here made of aluminum, carries a ball bearing centrally, referenced at 35 in FIG. 1. These bearings respectively support the front and rear ends of the shaft 1.
• the bearing 35 associated with the rear bearing 32 is smaller than that associated with the front bearing 31.
• the shaft 1 extends beyond the front bearing 31, a movement transmission member 5 in the form of a pulley being fixed on the shaft 1 to the outside of said bearing and integral in rotation with the shaft 1.
• This pulley is intended to cooperate with a V-grooved belt (not shown) by which the heat engine drives 1 • shaft 1 and the rotor assembly 2 when the machine electric works in mode generator.
• This pulley and the belt associated with it also makes it possible in the opposite direction to the electric machine to drive the heat engine, when said machine operates in starter mode.
• the transmission of movement between the shaft 1 and the heat engine of the vehicle as a variant may comprise gears, at least one chain of pulleys with variable spacing and / or at least one belt.
• the movement transmission member 5 can have many configurations and consist of a gear, a toothed wheel, a pulley etc.
• the ends of the winding 22 of the rotor 2 are each connected by a wire connection to slip rings 11 carried by the shaft 1.
• the windings of the stator assembly 34 are in turn connected by a wire connection to an electronic management device , not shown, arranged outside the machine.
• the machine is of the type described in document WO 01/69762 to which reference will be made for more details.
• the magnetic means 4 for monitoring the rotor 2 comprise an annular target 41 surrounding the shaft 1 and integral in rotation with this shaft 1, and at least one fixed sensor 42 disposed near the target 41 and cooperating therewith.
• the means 4 typically comprise three sensors 42, of the Hall effect type.
• the annular target 41 extends in a plane perpendicular to the shaft 1, is centered on the shaft 1 and is arranged on a rear axial side of the rotor 2.
• the target extends substantially around the rear bearing 35, at inside the stator 3. It is in one embodiment rigidly fixed to the metal rear fan 23 integral with the rotor 2, as visible for example in FIG. 12 of the above-mentioned document WO 01/69762, the fan being shaped at its free end to form an annular target support cup.
• This cup comprises an axial orientation portion extended outwardly by an annular rim of transverse orientation directed in the direction opposite to the axis XX '. The transverse edge is lower than the target.
• the target 41 comprises a central drive and / or fixing hub 413, linked in rotation to the rotor either directly, for example by cooperation of shapes, or indirectly.
• the hub 413 can for example be linked to the rotor via the fan, as in FIGS. 1 to 6 of document WO 01/69762.
• the hub 413 then comprises a metal cup of the aforementioned type, with an axial orientation portion and an annular rim of transverse orientation. This part is linked in rotation to the fan by cooperation of shapes.
• the hub 413 may comprise a cup, advantageously made of steel, provided with a rim of transverse orientation extended at its external periphery by an annular portion of axial orientation carrying the target by fixing. In the embodiment of FIGS.
• the hub 413 is linked in rotation to the rotor by means of the collector 12 carrying the rings 11.
• This collector is better visible in FIG. 8 of document FR A 2 710 200 to which see for more details. It comprises a tubular body 121 force fitted onto the rear end of the shaft 1, and a ring 122 centered on the shaft 1 and integral with the body 121.
• the body 121 carries the rings 11.
• the body 121 and the ring 122 are mutually separated, so that the body 121 is arranged outside the rear bearing 32 and the ring 122 inside the rear bearing 32, between the ball bearing 35 and the rotor 2, as shown see it in figure 1.
• the ring 122 carries elements 123 for electrical connection of the ends of the winding 22 of the rotor 2, these elements projecting radially outwards at from the ring 122. These elements 123 are electrically connected to the rings 11.
• the ring 122 also carries reliefs, for example projecting radially outwards, the hub 413 of the annular target 41 being linked in rotation to the 'ring 122 by shape cooperation with these reliefs.
• the sensors 42 are fixedly mounted on the rear bearing 32, inside the stator 3. These sensors are mounted on a sensor holder disposed on the side of the rear bearing opposite to the rotor as described below. Under the effect of the rotation of the target 41 together with the shaft 1, the magnetic field received by each sensor 42 varies.
• the electronic management device is of the type described in document FR A 2 745 444, and comprises a converter transforming the alternating current produced by the stator 3 into direct current, control means receiving the information from the sensors 42, and means for regulating the excitation current of the rotor 2.
• These regulation means are connected by a wire connection to a brush-carrying device, not shown, comprising brushes in contact with the rings 11 carried by the shaft 1.
• the target 41 comprises a magnetic part annular 411 and reinforcing means 412 enveloping the magnetic part 411 on a radially outer side.
• the central hub 413 of the target 41 comprises a metallic core 43 in the form of a cup, and a drive part 44 of plastic material overmolded on the metallic core 43.
• the metal core 43 has a central plate 431 in the form of a disc extending in a plane perpendicular to the axis XX ', an edge 432 drawn backwards carried by a radially outer side of the central plate 431, and a flange 433 extending the edge
• the plate 431 is pierced centrally with an orifice receiving the rotary shaft 1, and is pierced in a peripheral zone with several other orifices allowing the passage of the electrical conductors connecting the connection elements 123 to the rings 11.
• the magnetic part 411 is rigidly fixed on a radially outer face of the raised edge 432.
• the drive part 44 is overmolded on the metal core 43 and forms on a front side of the plate 431 of the reliefs cooperating with the reliefs of the ring 122 in order to link in rotation the manifold 12 and the annular target 41. It will be noted, as shown in FIGS.
• the fixing part 44 forms a second flange 441 parallel to the rim 433, of the same radial width as the latter, extending substantially in the plane of the plate 431, and slightly projecting outwardly relative to the latter.
• the magnetic part 411 comprises a radially inner part extending between the two flanges
• This magnetic part 411 is of substantially rectangular radial section, and has a radially external surface 414 substantially cylindrical, coaxial with the shaft 1.
• the magnetic part 411 is a plastomagnet, made up of magnetic particles dispersed in a plastic matrix.
• the radially outer surface 414 is coated by the reinforcement means 412, these forming a cylinder enveloping the annular magnetic part 411 over the entire circumference of this part.
• the reinforcement means can be mounted on the magnetic part of the target of FIG. 1, this magnetic part being advantageously magnetized in the end.
• the reinforcing means 412 form a thin layer 415 surrounding the magnetic part 411 on a radially outer side, this layer being pressed against the outer surface 414.
• the thin layer 415 has a cylindrical shape corresponding to that of the outer surface 414 and completely covers it. Its radial thickness is small relative to that of the annular magnetic part so that the overall dimensions of the machine are not generally modified.
• the thin layer 415 is full, as illustrated in FIGS. 5 and 6.
• the thin layer 415 has openings 416, as shown in FIGS. 2 to 4. These openings 416 are small relative to the axial width of the thin layer and its diameter.
• the thin layer 415 is pierced with a large number of openings 416, distributed regularly over its entire surface, axially and circumferentially.
• the thin layer can be made up of a network of braces defining square openings 416, as can be seen in FIG. 4. These braces form a regular mesh, and each have a width substantially equal to half the side. with a square opening. The width of a spider is considered perpendicular to its longitudinal direction.
• These braces extend obliquely to the axial edge of the thin layer 415, substantially at 45 °, and constitute two series. The braces of the same series are mutually parallel and are perpendicular to those of the other series.
• the openings 416 may also have other shapes, in diamond, round, rectangular, elliptical, triangular or other.
• the magnetic part 411 fills the openings 416 with the thin layer 415, so that it is flush on a radially outer side of the thin layer through the openings 416.
• the material of the magnetic part 411 which fills the openings 416 therefore fits perfectly into the cylindrical surface formed by the outer side of the thin layer.
• the reinforcement means 412 are made of a non-magnetic material. More specifically, they typically consist of aluminum and / or austenitic steel and / or plastic and / or a woven or non-woven textile material, for example felt.
• the plastic material may or may not include reinforcements, for example glass fibers.
• the reinforcement means 412 can be made integral with the annular magnetic part 411 in several different ways.
• the reinforcement means 412 can be hooped around the annular magnetic part 411, as shown in FIGS. 5 and 6.
• the reinforcement means 412 comprise in addition to the thin cylindrical layer 415 coaxial with the shaft 1, an annular wing 417 extending perpendicular to the shaft 1.
• This wing 417 is integral with an axial side of the thin cylindrical layer 4 15 and extends radially inwards from this one.
• the wing 417 is pressed against an axial face of the magnetic part 411.
• the internal diameter of the thin layer 415 is chosen to be slightly smaller than the external diameter of the magnetic part, the difference being chosen so as to obtain a good adjustment of the reinforcement means on the outer surface 414 of the magnetic part 411.
• the reinforcement means 412 can also be force-fitted around the annular magnetic part 411.
• the reinforcement means 412 can also be glued around the annular magnetic part 411, on the outer face 414.
• the reinforcement means can consist of an adhesive tape, coated with glue on a large face intended to be affixed on the outer face 414.
• the reinforcement means 412 can also be magnetoformed around the annular magnetic part 411. In this case they are made of a suitable metallic material
• the means reinforcement ens 412 can be thermoformed around the annular magnetic part 411.
• the annular magnetic part 411 is overmolded in the reinforcement means 412. This is made possible by the fact that this magnetic part 411 is a plastomagnet. This method makes it easy to obtain that the material constituting the magnetic part 411 fills the openings 416 of the reinforcement means 412. Furthermore, it is particularly suitable for the reinforcement means 412 made of fibrous materials, for example woven or non-woven textiles, because the natural porosity of these materials facilitates their mechanical attachment to the plastic matrix of the magnetic part 411 during overmolding. In yet another embodiment, the reinforcement means 412 are made of a plastic material and are molded around the annular magnetic part 411.
• the sensors 42 are mounted on a support 421.
• This support 421 comprises a main part 422 fixed, preferably with angular adjustment, in a rigid variant, on the rear bearing 32, on a side external to the stator 3 that is to say to the rotor 2, and three fingers 423 extending axially forwards from said main part and penetrating into the stator by openings in the rear bearing 32.
• the sensors 42 are rigidly fixed to free front ends of the fingers 423, and are arranged radially outside the annular target 41, facing the latter.
• An air gap of determined thickness separates the sensors 42 on the radially outer side of the thin layer 415 from the reinforcement means 412.
• the fingers 423 are connected together to form a single sector passing through a wider opening of the rear bearing.
• the radial thickness of the thin layer 415 is small relative to the air gap.
• the reinforcing means 412 are perforated by openings 416, these openings being filled with the material of the magnetic part 411, is particularly advantageous.
• the reinforcing means 412 constitute an armature for the annular magnetic part 411, allowing the latter to resist the centrifugal force created when the shaft 1 is driven at high speed. These reinforcing means significantly increase the mechanical resistance of the annular target to the centrifugal force. These reinforcing means are radially thin and compact. They do not significantly increase the distance between the magnetic part and the sensor.
• the assembly of the reinforcement means on the annular magnetic part can be carried out simply and quickly, using methods such as fitting and shrinking. Furthermore, the magnetic target reinforcement mode adopted here makes it possible to position the sensors radially outside the target. This arrangement is favorable since the implantation of the sensors is relatively easier outside the target than radially inside the target, or axially behind the target, as is well understood when considering FIG. 1. D ' other alternative embodiments of the machine described above can be envisaged without departing from the scope of the invention.
• the annular magnetic part may have a radial section which is not substantially rectangular.
• the annular magnetic part may not be a plasto-magnet, but be made of a material whose matrix is metallic or mineral.
• the reinforcement means 412 are perforated, the number of openings made in the thin layer and the size of these openings can vary very widely, provided that the mechanical strength of the annular target is sufficient.
• the present invention is not limited to the embodiments described.
• the rotor is in a variant of the type with salient poles around which excitation windings are wound.
• the alternator is with salient poles, around which are wound excitation coils, and with permanent magnets integrated in the rotor as described for example in the document WO
• the casing of the alternator may comprise more than two parts, for example three parts connected together for example by means of screws. These three parts comprise the two bearings arranged on either side of a central part internally carrying the stator assembly.
• the structures can be inverted, the target holder being located between the bottom of the front bearing 31 with a hole for the passage of fingers 423 and the adjacent flange of the pole wheel 21. The sensor holder is then fixed on the face of the bearing 31 turned towards the opposite of the rotor.
• the hub 413 can be glued to the fan.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Brushless Motors (AREA)
• Synchronous Machinery (AREA)

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• 2004
  • 2004-04-30 FR FR0404675A patent/FR2870055B1/fr not_active Expired - Fee Related
• 2005
  • 2005-04-27 WO PCT/FR2005/001040 patent/WO2005117244A1/fr active Application Filing
  • 2005-04-27 DE DE112005000419.8T patent/DE112005000419B4/de not_active Expired - Fee Related
  • 2005-04-27 JP JP2007510076A patent/JP4787242B2/ja not_active Expired - Fee Related

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