CN116569455A - Current collector for rotating electrical machine - Google Patents

Abstract

Current collector (1) for a rotor (4) of a rotating electrical machine, having a longitudinal axis (X-X) and comprising a lower collecting ring (10 a) and an upper collecting ring (10 b) separated from each other by an annular axial space, a spacer ring (20) accommodated in the annular axial space, a lower rail (16 a) electrically connected to the lower collecting ring and an upper rail (16 b) electrically connected to the upper collecting ring, a protective element (19) comprising an electrically insulating guiding zone (191 b) positioned between the upper rail (16 b) and the lower collecting ring (10 b), characterized in that the spacer ring (20) comprises at least one internal device (202), the protective element (19) comprising at least one external device (196) cooperating with the internal device to prevent the spacer ring from rotating relative to the protective element.

Description

Current collector for rotating electrical machine

Technical Field

The present invention relates to a current collector for a rotating electrical machine, and also to a corresponding rotating electrical machine. The invention has particular, but not exclusive, application in the field of alternators, starter-alternators, electric motors and reversible electric machines for vehicles or unmanned aerial vehicles. These may be, for example, automobiles, scooters, bicycles or motor tricycles.

Background

Additional slip ring assemblies are known that are manufactured by over-molding an insulating material over an electrically conductive element, which slip ring assemblies are intended to be mounted by press-fitting onto a knurled or non-knurled shaft of an alternator rotor.

More specifically, as described in document FR2710197, a current collector of this type comprises a substantially cylindrical body having on its outer surface two slip rings and two guide rails, each welded via one of its ends to the inner face of one of the slip rings. At the opposite end, each rail is provided with a connection element, such as a hook, for connecting to the conductors of the rotor winding in order to supply it with electricity. In the following, the adjective "upper" will refer to an axial position close to the motor cover. The adjective "lower" will refer to an axial position near the rotor of the motor.

When the current collector is mounted on an alternator shaft, the forces involved in the press-fitting lead to the risk of microcracks in the overmolded plastic part, which has a low plastic deformability, thus causing problems of overall electrical insulation. Furthermore, most modern current collectors have weaknesses in both dielectric testing and passing through the oven.

Disclosure of Invention

The present invention aims to effectively remedy this drawback. To this end, a first aspect of the invention relates to a current collector for a rotor of a rotating electrical machine, the current collector having a longitudinal axis. The current collector includes: a lower slip ring and an upper slip ring separated from each other by an axial space; a spacer ring accommodated in the axial space; a lower rail electrically connected to the lower slip ring and an upper rail electrically connected to the upper slip ring; and a protective element comprising an electrically insulating guiding region and positioned between the upper rail and the lower slip ring. According to the invention, the spacer ring comprises at least an inner means and the protection element comprises at least an outer means, said inner means cooperating with said outer means to prevent rotation of the spacer ring relative to the protection element.

Such a current collector makes it possible to control the distance between the two copper rings, thereby avoiding any risk of short circuits. Furthermore, the lower slip ring is insulated from the upper rail to avoid any short circuit between these two elements. Furthermore, two guide rails are guided to control the position of the connection elements, into each of which copper wires are soldered. Finally, such a current collector makes it possible to eliminate the risk of rotation of the spacer ring, for example when the upper and lower slip rings are subjected to a machining operation. This then has the advantage that the risk of detachment of the spacer ring is avoided or the risk of deformation of the region between the upper and lower slip ring during the machining phase is avoided.

The current collector according to the invention is preferably a current collector with a rotating slip ring.

According to one embodiment, the external device is defined by the protective element, not by a component mounted on the protective element. According to this embodiment or not, the protection element may be a one-piece element.

According to one embodiment, the internal device is a protrusion or recess and the external device is a recess or protrusion, respectively. In other words, one of the means is a protrusion and the other means is a recess. The use of such means makes it possible to ensure the positioning of the spacer rings without increasing the complexity of the structure of the collector.

According to one embodiment, the protrusion is a post.

According to one embodiment, the upright has a bevel. The inclined surface makes it possible to form a guide portion for guiding the insertion of the upright into the associated recess.

According to one embodiment, the upright forms a semi-cylindrical protrusion.

According to one embodiment, the recess is an opening.

According to one embodiment, the opening is elongated by an open-ended slot. By "open-ended" is meant that the slot extends the opening to the upper end of the element in which the slot is formed, i.e., the protective element or spacer ring.

Optionally, the recess is a slot, in particular a semi-cylindrical slot.

According to one embodiment, the current collector includes a plurality of internal devices and a plurality of external devices.

According to one embodiment, the spacer ring has an inner circumferential surface comprising the inner means.

According to one embodiment, the outer surface of the spacer ring is located in a continuation of the outer surface of one of the slip rings.

According to one embodiment, the current collector comprises a body intended to be mounted on a rotor shaft of a rotating electrical machine and to be positioned at least partially between said shaft and a slip ring.

According to one embodiment, the body is formed of an electrically insulating material, such as a polymer or a composite material.

According to one embodiment, the protective element has an upper cutout accommodating the upper rail and a lower cutout accommodating the lower rail.

According to one embodiment, the upper cutout extends to the upper end of the protection element.

According to one embodiment, the undercut extends to the lower end of the protection element.

According to one embodiment, the protection element further comprises a rim at its lower end. The edge increases the rigidity of the protection element, allowing to maintain the roundness (roundness) of the protection element.

According to one embodiment, the internal device and the external device are complementary to each other.

According to one embodiment, the current collector comprises two internal devices and two external devices. Thus, the first internal device mates with the first external device and the second internal device mates with the second external device.

According to one embodiment, the current collector comprises exactly two slip rings, namely: only the lower slip ring and the upper slip ring are included. Thus, there are no additional rings other than those described above. According to this embodiment, the current collector may comprise exactly two rails, namely: only the lower rail and the upper rail are included.

The invention also relates to a rotating electrical machine comprising at least one current collector as described above.

Drawings

The invention and its various applications will be better understood from a reading of the following description and a review of the accompanying drawings, in which:

fig. 1 is a sectional view depicting an example of a part of a rotary electric machine according to the present invention;

fig. 2 is a perspective view of the current collector of fig. 1;

fig. 3 is an exploded perspective view of the current collector of fig. 2;

FIG. 4 is a perspective view of an assembled protective element and spacer ring according to one example of the invention;

FIG. 5 is a perspective view of an assembled protective element, connection rail, and connection element according to one example of the invention;

fig. 6 is a partially exploded perspective view of a current collector according to a first embodiment of the present invention;

fig. 7 is a partially exploded perspective view of a current collector according to a second embodiment of the present invention;

fig. 8 is a partially exploded perspective view of a current collector according to a third embodiment of the present invention; and is also provided with

Fig. 9 is a partially exploded perspective view of a current collector according to a fourth embodiment of the present invention.

The drawings are presented as a purely non-limiting indication of the invention. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar or analogous elements.

Detailed Description

Rotating electrical machines such as alternators, starter-alternators, electric motors, or reversible electric machines may be provided on vehicles, particularly motor vehicles having internal combustion engines. The rotating electrical machine is configured to convert mechanical energy from the internal combustion engine into electrical energy, with the specific purpose of recharging the battery of the vehicle and providing electrical power to the on-board network of the vehicle when the machine is operating as a generator. The rotating electrical machine may also have a motor operating mode in which the rotating electrical machine converts electrical energy into mechanical energy, in particular for starting an internal combustion engine of a motor vehicle.

Fig. 1 is a cross-sectional view depicting a portion of an internally ventilated multi-phase rotating electrical machine for a vehicle. The motor includes: a drive pulley 11, which works from left to right, i.e. front to back in fig. 1, which drive pulley 11 is fixed to the front end of the shaft 2, while the rear end of the shaft 2 carries slip rings 10a, 10b belonging to the current collector 1. The axis X-X of the shaft 2 constitutes the axis of rotation of the motor and the current collector.

The shaft 2 has a rotor 4 centrally fixed to the shaft 2, the rotor 4 being provided with an excitation winding 5, the ends of the winding 5 being connected to the current collector 1 by a wired connection. The rotor 4 is here a claw-pole rotor and has two claw poles 6, 7, each carrying a front fan 8 and a rear fan 9, respectively, each of the front fan 8 and the rear fan 9 having blades.

Each claw pole has axial teeth directed towards the other claw pole, and the teeth of one claw pole are interposed between the teeth of the other claw pole so as to form magnetic poles when the winding 5 is activated due to the slip rings of the current collector 1, each slip ring being in contact with a brush (not shown) carried by the brush holder 100, in this example the brush holder 100 being fixed to a voltage regulator (not visible). The brushes are oriented radially with respect to axis X-X, while the rings 10a, 10b are oriented axially with respect to axis X-X. Each brush is connected to a metal braid which is connected to a terminal which is itself connected to the vehicle ground and the positive terminal of the vehicle battery, respectively.

The motor in this example comprises a rectifier 110, for example a diode bridge (two of these diodes are visible in fig. 1), converting alternating current into direct current. Alternatively, the electric machine may comprise a power module comprising transistors of the MOSFET type, in particular when the alternator is of the reversible type and consists of a starter-alternator. The device 110 itself is electrically connected, on the one hand, to the phase outputs belonging to the windings 12 comprised by the stator 13 and, on the other hand, to the on-board network and to the battery of the motor vehicle. The stator 13, which in the case of an alternator acts as an armature, surrounds the rotor 4 and has a body 14 internally provided with axial cuts (not visible) for the passage of the wires or hairpin coils (hairpins) contained in the windings 12. The winding 12 has winding overhangs (not shown) that project axially on each side of the body 14.

It should be noted that the purpose of the voltage regulator is to control the current flowing through the field winding 5 in order to regulate the voltage delivered to the on-board network and the vehicle battery via the current rectifier means.

Fans 8, 9 extend near a front end plate (referred to as front support 150) and a rear end plate (referred to as rear support 160), respectively, which belong to a stationary housing of the motor, which is electrically grounded. The supports 150, 160 are perforated so that when the assembly consisting of fans 8, 9, plus rotor 4, plus shaft 2 is driven in rotation by pulley 11, the interior of the motor is ventilated by fans 8, 9. This ventilation allows cooling of the windings 12, 5 and cooling of the brush holder 100 with the regulator and rectifier device 110. The path followed by the cooling fluid, in this case air, through the openings in the supports 150, 160 is indicated by arrows in fig. 1.

Here, the device 110, the brush holder 100 and the perforated protective rear cover 21 are supported by the rear support 160, so that the rear fan 9 can be stronger than the front fan 8. The supports 150, 160 are connected to each other, in this case using screws or through bolts (not visible), to form a housing intended to be mounted on a fixed part of the vehicle.

The bearings 150, 160 each centrally carry rolling contact ball bearings 17, 18 to support the front and rear ends of the shaft 2 passing through the bearings 150, 160 while allowing the front and rear ends of the shaft 2 to rotate, which front and rear ends of the shaft 2 carry the pulleys 10 and the rings 10a, 10b of the current collector 1. The supports have a hollow shape and here each bearing has a perforated transverse oriented portion carrying the rolling contact bearings 17, 18 and a perforated axial oriented portion having an inner stepped diameter for centering the body 14 of the stator 13 and axially holding the body 14 of the stator 13 when the two supports are connected to each other to form a housing.

The blades of the fans 8, 9 may extend radially above the housing provided by the support 150, 160 for mounting the rolling contact bearings 17, 18, thereby ventilating the rolling contact bearings 17, 18.

As can be seen in fig. 2 and 3, the current collector 1 comprises a body 3 mounted on a shaft 2. The body 3 is at least partially located between the shaft and the slip rings 10a, 10b. The body is formed in particular of an electrically insulating material, such as a polymer or a composite material. The body 3 has an annular first part 34 at the front, a cylindrical second part 35 carrying the slip ring at the rear, and a connecting intermediate part 36 extending between the first and second parts. The intermediate portion 36 comprises two arms 361a, 361b. The first portion, the second portion and the intermediate portion may be formed of the same material to constitute a one-piece element. For example, the portions may be manufactured by injection molding a polymer, a composite material, or a plastic (e.g., a thermoset or thermoplastic), and are clearly visible in the exploded view of the current collector of fig. 3.

The current collector 1 comprises two axially extending connecting rails 16a, 16b, which are in particular in the form of strips. Each connection rail has a portion embedded in one of said arms 361a, 361b, and a connection element 15a, 15b arranged at one end, so that an electrical connection to the free end of the associated wire of the winding 5 of the rotor 4 can be seen. The connection is achieved, for example, by a first-step crimping and a subsequent second-step soldering. The other end of each rail 16a, 16b is electrically connected (in particular by welding) to the inner face of one of the rings 10a, 10b in a connection region that is not drawn.

Each slip ring 10a, 10b has the shape of a hollow ring with an axis X-X made of an electrically conductive material, preferably copper. The connection between the ring and the rail may be produced, for example, using ultrasonic welding techniques. A distinction is made between the ring 10a called "lower" which is axially closest to the claw poles 6, 7 and the ring 10b called "upper" which is axially closest to the protective cover 21. In other words, the lower ring 10a is axially located between the upper ring 10b and the claw poles 6, 7, more specifically between said upper ring 10b and the rear end plate 160. The lower rail 16a is connected to the lower slip ring 10a and the upper rail 16b is connected to the upper slip ring 10b.

The current collector 1 further comprises a protection element 19, which protection element 19 is configured to insulate the connection between the rails 16a, 16b and the respective rings 10a, 10b from the shaft 2. The protection element 19 is arranged at least partially surrounding the cylindrical second portion 35 of the body 3. Said elements being arranged radially between the body 3 and the slip rings 10a, 10b. The protection element 19 comprises a guiding zone 191a, 191b for guiding each rail 16a, 16b and extending axially with respect to the axis X-X. The two guide areas 191a, 191b are substantially diametrically opposite one another.

In this case, the guide region 191a is formed by a slit extending axially of the protective element 19, which is referred to as a lower slit 194a, as shown in fig. 4 and 5. The lower cutout 194a extends to the upper axial end of the protective element and enables electrical contact to be established between the lower rail 16a and the lower slip ring 10 a.

The guide zone 191b comprises a groove extending axially along the inner wall of the protection element 19, which groove extends between the ring 10a and the guide rail 16b, allowing said ring to be electrically insulated from said guide rail. Guidance may be provided by two insulating walls 192, 193, which insulating walls 192, 193 extend axially and are arranged circumferentially one on each side of the groove. The groove is axially elongated by an upper cutout 194b extending to the upper axial end of the protective element. The upper cutout enables electrical contact to be established between the guide rail 16b and the slip ring 10b. The guide region 191b may extend axially along the entire length of the protection element 19. The guide region 191b extends as a radial projection toward the axis X-X. The protrusion may mate with a correspondingly shaped recess formed on the outer periphery of the cylindrical second portion 35 of the current collector.

The protective element 19 may also comprise a rim 195 at the lower end. The rim 195 bears against the axial end face of the lower slip ring 10 a. Such a rim 195 allows a controlled positioning of the protective element 19 with respect to the slip rings 10a, 10b, while increasing the rigidity of the protective element, so that the roundness of the protective element can be maintained.

The current collector 1 further comprises a spacer ring 20 having an annular shape with an axis X-X, so that electrical insulation between the slip rings 10a and 10b can be ensured. The spacer ring 20 comprises an annular collar 201 arranged axially between the rings to maintain an axial spacing between the rings, in this case a substantially constant spacing. Here, the outer diameter of the liner 201 corresponds to the outer diameters of the slip rings 10a and 10b. In other words, the outer surface of the spacer ring is arranged in a continuation of the outer surface of one of the slip rings 10a or 10b. Notably, the inner diameter of the collar 201 substantially corresponds to the inner diameter of the slip rings 10a and 10b.

The current collector is assembled, for example, as follows: the lower slip ring 10a slides over the protective element 19 until the lower axial end face of the ring abuts against the rim 195 of the protective element. The spacer ring 20 is then slid over the protection element 19 such that the lower axial end face of said ring 20 is in contact with the upper axial end face of the lower slip ring 10 a. Finally, the upper slip ring 10b slides around the protection element until the lower axial end face of said ring 10b abuts against the upper axial end face of the spacer ring 20. The connecting rails 16a, 16b are positioned and electrically connected to the slip rings, the body 3 being injection molded.

The spacer ring 20 has at least one internal means 202, which internal means 202 are arranged on the inner circumference of the ring, namely: on the face facing the axis X-X. Furthermore, the protection element 19 comprises at least one external device 196, which external device 196 is positioned on the outer peripheral surface of the element, namely: on a face radially opposite to the inner face facing the axis X-X. The inner device 202 cooperates with the outer device 196 to prevent rotation of the spacer ring relative to the protective element. In the examples described below, the spacer ring 20 and the protection element 19 each comprise several means 202, 196, in particular two means, preferably arranged radially opposite each other.

In the example of the first embodiment shown in fig. 6, the inner means 202 of the spacer ring 20 are protrusions and the outer means 196 of the protection element 19 are recesses.

Here, more specifically, the spacer ring 20 includes two internal devices, each formed by a respective upright 202a, 202b protruding from the inner peripheral surface of the collar 201. Each post forms a protrusion on the inner surface of the ring such that the distance between the post and the axis X-X is smaller than the distance between the inner face of the collar 201 and the axis. Furthermore, the distance between the upright and the axis X-X is smaller than the corresponding distance between the slip rings 10a, 10b and said axis. In other words, the inner diameter of the spacer ring measured at the posts 202a, 202b is smaller than the respective inner diameter of the slip rings 10a, 10b. In this example, the upright extends in a radial direction over the entire height of the collar 201.

In this embodiment shown in fig. 6, the protective element 19 comprises two external devices 196, each external device 196 forming a recess, which recess is in this case an opening, in particular a through-opening. More specifically, the protection element 19 comprises two diametrically opposite openings 196a, 196b. Each opening extends axially to the upper edge of the protective element. The upper edge of the protective element is formed by the axial end of said element, which is arranged closest to the protective cover 21 of the motor. The openings 196a, 196b are configured such that, when assembled, the posts 202a, 202b belonging to the spacer ring 20 can slide in each opening, respectively. Thus, after assembly, the lower axial end face of each post abuts the closed end of the opening, which is the lower axial end of the opening. When assembled, the posts engage in the openings, preventing any rotational movement of the spacer ring 20 relative to the protective element 19.

In the example of the second embodiment shown in fig. 7, the inner means 202 of the spacer ring 20 are protrusions and the outer means 196 of the protection element 19 are recesses.

Here, more specifically, the spacer ring 20 includes two internal devices, each formed by a respective upright 202a, 202b protruding from the inner peripheral surface of the collar 201. The description of the internal device 202 of the first embodiment shown in fig. 6 also applies to this second embodiment. In addition to having the features of the first embodiment, each post 202a, 202b has a bevel 203. In this case, each inclined surface 203 extends in the axial direction such that the inner diameter of the pillar increases in the axial direction toward the lower edge of the pillar. In other words, the distance between the lower axial end of the upright and the axis X-X is greater than the distance between the upper axial end of said upright and said axis. Here, the chamfer 203 extends only over a part of the pillar, in particular over an axial part, which represents less than half the height of the pillar in the axial direction.

The protection element 19 described in this second embodiment comprises two external devices 196, each forming a recess. Here, each recess is formed by a through opening 196a, 196b, the through openings 196a, 196b extending axially through a slot 197. Each slot 197 extends axially between the respective opening 196a, 196b and the upper axial end of the protective element. The openings 196a, 196b and slots 197 are configured such that, upon assembly, each lug 202a, 202b of the spacer ring 20 slides in one of the slots 197, the ramp acting as a guide during assembly until the lug snaps into the corresponding opening 196a, 196b. Thus, after assembly, the lower axial end face of each post abuts the closed end of the opening. When assembled, the posts engage in the openings, preventing any rotational movement of the spacer ring 20 relative to the protective element 19. Furthermore, in this embodiment, the post is also axially fixed in the opening.

In the example of the third embodiment shown in fig. 8, the inner means 202 of the spacer ring 20 are protrusions and the outer means 196 of the protection element 19 are recesses.

Here, more specifically, the spacer ring 20 includes two internal devices, each formed by a respective upright 202a, 202b protruding from the inner peripheral surface of the collar 201. In this embodiment, each pillar differs from the pillar of the first embodiment only in its shape. In this example, each upright has in this case the form of a semi-cylindrical projection. In this embodiment as well, the protection element 19 comprises two external means 196, each external means 196 forming a recess, which recess is a slot 198. Each slot has a semi-cylindrical shape. Each slot extends axially to an upper edge of the protective element. The slots are configured such that, when assembled, the semi-cylindrical projections belonging to the spacer ring 20 can slide in each slot, respectively. Thus, after assembly, the lower axial end face of each post abuts the lower axial end of the corresponding slot. When assembled, the posts engage in the slots, preventing any rotational movement of the spacer ring 20 relative to the protective element 19.

In the example of the fourth embodiment shown in fig. 9, the inner means 202 of the spacer ring 20 are recesses and the outer means 196 of the protection element 19 are protrusions.

Here, more specifically, the protection element 19 comprises two internal means, each formed by a respective upright 199 protruding from the peripheral surface of said element. The upright extends in the axial direction over part of the height of the element 19. Here, for example, each column 199 has the form of a semi-cylindrical protrusion. Notably, posts 199 are disposed radially opposite each other.

Still in this fourth embodiment, the spacer ring 20 comprises two internal means 202, each internal means 202 forming a recess, in this case a slot 204. More specifically, the spacer ring 20 includes two diametrically opposed slots 204. Each slot extends axially over the entire height of the collar 201. The slots are configured such that, when assembled, post 199 may slide in each slot separately. When assembled, the posts engage in the slots, preventing any rotational movement of the spacer ring 20 relative to the protective element 19.

In either embodiment, the spacer ring 20 and the protective element 19 are made in particular of an electrically insulating material, such as a polymer or a composite material. The protective element 19 and the spacer ring 20 can be made of plastic, thermoplastic or thermosetting plastic, for example.

Of course, the invention is not limited to the embodiments described with reference to the drawings, and alternative embodiments may be envisaged without departing from the scope of the invention.

Claims (12)

1. A current collector (1) for a rotor (4) of a rotating electrical machine, having a longitudinal axis (X-X) and comprising:

a lower slip ring (10 a) and an upper slip ring (10 b) separated from each other by an axial space,

a spacer ring (20) accommodated in the axial space,

a lower rail (16 a) electrically connected to the lower slip ring and an upper rail (16 b) electrically connected to the upper slip ring, and

a protective element (19) comprising an electrically insulating guiding region (191 b) and being positioned between the upper rail (16 b) and the lower slip ring (10 b),

characterized in that the spacer ring (20) comprises at least an inner means (202) and the protection element (19) comprises at least an outer means (196), the inner means cooperating with the outer means to prevent rotation of the spacer ring relative to the protection element.

2. The current collector of claim 1, wherein the inner means (202) is a protrusion or recess and the outer means (196) is a recess or protrusion, respectively.

3. The current collector of claim 2, wherein the protrusions are posts.

4. A collector as claimed in claim 3, wherein the posts have a chamfer.

5. The current collector of claim 3 or 4, wherein the pillars form semi-cylindrical protrusions.

6. The current collector according to any one of claims 2 to 5, wherein the recess is an opening.

7. The current collector of claim 6, wherein said opening is elongated by an open slot.

8. The current collector according to any one of claims 2 to 5, wherein the recess is a slot, in particular a semi-cylindrical slot.

9. The current collector of any of the preceding claims, wherein the current collector comprises a plurality of internal devices (202) and a plurality of external devices (196).

10. The current collector according to any of the preceding claims, comprising exactly two slip rings, namely: only the lower slip ring (10 a) and the upper slip ring (10 b) are included.

11. The current collector according to any of the preceding claims, wherein the protection element (19) is a one-piece element.

12. A rotating electrical machine comprising a current collector (1) according to any of the preceding claims.