Rotary commutator for an electric machine

Abstract

The invention relates to a rotary commutator (34) for the rotor of an electric machine, comprising: - a body (36) provided with at least one rotary contact (38), - at least one connection tab (46), extending from the body (36), electrically connected to said rotary contact (38), and able to be electrically connected and attached to a winding wire of the rotor, said commutator (34) guiding said winding wire between one end (50) of said wire and said winding, said commutator (34) comprising at least one attachment tab (56) extending from the body (36), arranged between one end (50) of said wire and said winding, and capable of being attached to said wire, in order to successively receive the wire in the tabs (46, 56), attach the wire (19) only to one of said tabs (46, 56) close to the end (50), mechanically tension the wire between said tabs (46, 56), then attach same to the other of said tabs (46, 56).

Description

Rotating collector for an electric machine Technical field of the invention

[0001] The invention relates to a rotating collector for an electrical machine, and an electrical machine comprising such a collector. Technical background

[0002] A slip ring, or commutator, is a crucial electromechanical component in electrical machines. In electrical machines such as generators or motors, slip rings allow the transmission of high-power electrical currents between stationary and moving parts. For example, in an electric motor, they transmit electricity to a rotor winding. To achieve this, a slip ring typically consists of a body with rotating contacts in the form of conductive rings flush with the periphery of the body. Carbon or metal brushes mounted on the stator brush the conductive rings to maintain the electrical connection while allowing rotation.

[0003] The conductive rings are internally connected to the collector via connecting lugs arranged around the periphery of the collector body.

[0004] The connecting tabs are electrically connected and mechanically attached to the winding. Conventionally, one strand of the winding wire is cold-crimped to one of the connecting tabs and then wound around a portion of the commutator body before entering the rotor. There, it is wound around the rotor poles before a second strand of the wire exits the rotor and is also cold-crimped to a second connecting tab. Due to connection and mechanical strength requirements, the winding wire undergoes a second, hot-crimping of its strands to the connecting tabs.

[0005] The commutator is conventionally fitted onto a rotor shaft. Due to the dimensions of the crimping tools, it is not possible to perform hot and cold crimping once the commutator has been fully fitted onto the rotor shaft. Therefore, these crimps are only performed when the commutator is partially fitted onto the rotor shaft.

[0006] As a result, the recoil of the commutator during its final fitting onto the rotor shaft produces a loosening of the winding wire, particularly with regard to its longest strand outside the poles, namely the first strand which is located between the first of the legs and the winding.

[0007] This loosening can be detrimental to the mechanical strength of the first strand during the operation of the electric machine. Indeed, due to its relative freedom, the first strand is susceptible to alternating accelerations and stresses as the rotor accelerates, which can eventually cause it to break and consequently stop the electric machine.

[0008] Therefore, there is a real need for a collector that can cancel out or compensate for this release.

[0009] The invention satisfies this need by providing a collector capable of ensuring tension on the winding wire prior to the final fitting of the collector in order to compensate for the slack in the wire induced by said winding.

[0010] To this end, the invention proposes a rotating collector for an electric machine rotor, said collector comprising:

[0011] - a body with axis A comprising at least one rotating contact,

[0012] - at least one first connection tab, protruding from the body, electrically connected to said at least one rotating contact of said body, and capable of being electrically connected and fixed to a winding wire of the rotor,

[0013] said collector comprising at least one fixing tab protruding from the body, said fixing tab being intended to be arranged between one end of said wire and said winding, and suitable for being fixed to said winding wire, to allow successively receiving the wire in the first connection tab and in the fixing tab, fixing the end of said winding wire only to that of said tabs which is closest to said end, putting the winding wire under mechanical tension between said tabs, and then fixing it to the other of said tabs.

[0014] The invention advantageously provides tension to the winding wire at the point where the wire connects to the commutator, the part most prone to slack. This tension compensates for the slack in the winding wire as the commutator retracts during its final mounting onto the rotor shaft. This limits the wire's movement under inertial forces, thus reducing the risk of breakage at this point.

[0015] According to various additional features of the invention, which may be taken together or separately and which constitute so many embodiments of the invention:

[0016] - said collector is configured to guide said winding wire between said wire end and said winding,

[0017] - said first connecting leg is radial,

[0018] - said mounting bracket is radial,

[0019] - the fixing tab is suitable for being fixed to the end of the wire upstream of said first connection tab,

[0020] - the first connection tab and / or the fixing tab comprises a main extension part and a wing extending from said part, said wing being capable of being folded over the wire in contact with the main extension part to fix said wire to said first connection tab and / or to said fixing tab by crimping,

[0021] - the first connection tab and the fixing tab are spaced at a predetermined distance configured to allow the passage between said tabs of a tool capable of applying radial stress to said wire towards the body,

[0022] - the first connection tab and the fixing tab are attached to a so-called input strand of the winding wire,

[0023] - the collector also includes a second connection tab intended to be attached to a so-called output strand of the winding wire,

[0024] - the connecting tabs are diametrically opposed,

[0025] ,

[0026] - said collector is configured to guide said winding wire between its end and said winding over at least 180°, - said collector is provided with means for guiding said input strand comprising: an angular sector of radial flange extending around the body between the connection lugs, a radial finger for retaining the input strand extending angularly downstream of the connection lug receiving the output strand,

[0027] - said body is tubular with axis A.

[0028] - said body has a surface in which said rotating contact is flush.

[0029] The invention also relates to an electric machine rotor comprising at least: a hub of axis A, having a plurality of radial poles arranged angularly at regular intervals around the axis, a shaft of axis A passing through said hub, coupled to said hub, and having one end protruding out of said hub, a continuous winding wire wound on said poles, the rotating commutator of the type described above, fitted onto the end of said shaft, and electrically connected to the input strand, or even to said output strand, of said continuous winding wire.

[0030] The invention also relates to an electrical machine comprising at least one stator and one rotor of the type described above.

[0031] The invention also relates to a method for assembling a rotor of the type described above, comprising the steps of:

[0032] i) partially fit the rotating commutator onto the end of the rotor shaft,

[0033] (ii) insert the input strand into said first connection lug and said fixing lug intended to receive the input strand, and cold crimp the wire into that of said first connection lug and fixing lug closest to the end of said input strand,

[0034] iii) arrange the input strand in the guide means of the collector,

[0035] iv) wind the rotor wire,

[0036] (v) secure the output strand of the winding wire, in particular to the commutator,

[0037] vi) position a squeezing tool in contact with the input strand between said first connection lug and said fixing lug,

[0038] vii) to apply radial stress to the input strand towards the collector body using said stressing tool,

[0039] viii) hot crimp the input strand at least in said connection tab and in the fixing tab,

[0040] ix) release the tension on the input strand by the tensioning tool,

[0041] x) fully fit the rotating collector onto the end of the rotor shaft.

[0042] According to other characteristics of this process:

[0043] - during step v) the output strand of the winding wire is fixed to the collector by cold crimping the end of the output strand to at least the second connection lug receiving the output strand,

[0044] - during step viii) the output strand of the winding wire is further hot-crimped at least in the second connection tab receiving the output strand.

[0045] The invention finally relates to a excitation tool for implementing the aforementioned process comprising an active end, in particular a roller, having a groove adapted to cooperate with the winding wire. Brief description of the figures

[0046] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent in the course of the detailed explanatory description which follows, of at least one embodiment of the invention given by way of purely illustrative and non-limiting example, with reference to the accompanying schematic drawings, among which:

[0047] This is a schematic cross-sectional view of an electric machine rotor;

[0048] This is a detailed view at the end of an electric machine rotor according to the invention;

[0049] This is a perspective view of a rotating collector according to the invention;

[0050] This is a perspective view of an electric machine rotor according to the invention;

[0051] This is a detailed perspective view illustrating the mechanical tensioning of the winding wire in the collector according to the invention;

[0052] This is a block diagram illustrating the steps of a method for assembling an electric machine rotor according to the invention. Detailed description of the invention

[0053] Figures 1, 2, and 4 show a rotor 10 of an electric machine according to the invention. The rotor 10 comprises a shaft 12 with axis A passing through a hub 13, this hub 13 carrying an armature 14 having a plurality of sectors (not shown) defining as many poles 16 arranged angularly at regular intervals around the axis A. One end 15 of the shaft 12 protrudes from the hub 13.

[0054] Each of the poles 16 is wound, that is, it comprises a portion 18 of a continuous winding wire 19 which is wound onto a corresponding sector of the armature 14. All the portions 18 of the wire 19 wound onto the armature 14 form the total winding 21 of the rotor. The continuous wire 19 is connected to the winding 21 at one of the poles 16, is wound along the portion 18 on that pole 16, then passes from pole 16 to pole 16 to be wound around each armature sector of each pole 16 and finally emerges from the winding 21. The poles 16 are separated by spacers 20 and contained by flanges 26 which are held by tie rods 28 with axes parallel to the axis A so as to form a cage 22.

[0055] The winding wire 19 enters and exits the poles 16, and for this purpose, its electrical connection comprises two strands: an input strand 30 and an output strand 32. It is understood that this terminology is a convention intended solely to distinguish these strands and is not limiting to the invention. However, the input strand 30 may be considered the strand from which the winding 21 is initiated around the armature 14.

[0056] To ensure the supply of the winding 21, as shown in figures 1 to 4, a rotating collector 34 is fitted onto the shaft 12. The collector 34 is electrically connected to the input strands 30, or even to the output strand 32, of the continuous wire 19 of the winding 21.

[0057] As illustrated in Figures 1 to 4, and more particularly in Figure 1, the collector 34 comprises a body 36 with axis A including at least one rotating contact 38. As shown in Figure 1, without limiting the invention, the body 36 of the collector is generally tubular in shape. The body 36 has a surface in which said rotating contact 38 is flush.

[0058] Preferably, it comprises a front section 40 with two flush annular conductive rings 38 forming two rotating contacts. These rings 38 are, for example, suitable for rubbing against the conductive brushes of the motor (not shown). The body 36 also comprises a rear section 42 including a shaft 41 which is connected to the front section 40, here by two diametrically opposed arms 44.

[0059] At its rear section 42, the body 36 has at least one first radial connection lug 46 projecting from the body 36, and in particular from the shaft 41 of its rear section 42. Here, the body 36 advantageously has two radial connection lugs, namely the first connection lug and a second connection lug 48. These lugs are preferably diametrically opposed. Each lug 46, 48 is electrically connected to one of the rotating contacts 38 of the body 36, for example, via internal connections in the arms 44. Each of the lugs 46, 48 is suitable for electrical connection and attachment to the rotor winding wire 19.

[0060] In particular, the first connecting pin 46 is connected to the input strand 30 of wire 19, and the second connecting pin 48 is connected to the output strand 32 of wire 19. By convention, the rotary contact 38 connected to the first connecting pin is called the input rotary contact and the rotary contact 38 connected to the second connecting pin 48 is called the output rotary contact.

[0061] The collector 34 is further configured to guide said winding wire 19 between an end 50 of said wire 19 and the winding 21, in particular at said input strand 30. As shown in the figures, the end 50 of wire 19 is also the end of the input strand 30 of this wire 19.

[0062] In the embodiment shown here, which is not a limitation of the invention, it is the input strand 30 of the winding wire 19 that is guided by the commutator 34 between its end 50 and the winding 21. For this purpose, the body 36 includes means for guiding the input strand 30, which essentially comprise an angular sector 52 of radial flange extending around the rear section 42 of the body 34 between the first and second connecting lugs 46, 48. These guiding means also include a radial finger 54 for retaining the input strand 30, which extends radially from the barrel 41 angularly downstream of the second connecting lug 48 receiving the output strand 32. The input strand 30 is thus guided around the rear section 42 between its end 50 and the finger 54 around the barrel 41, and in particular by the flange sector 52 at an angle determined (here at least 180°), then rests on finger 54 before joining winding 21.

[0063] The input strand 30 of the winding wire 19 is first fixed to the commutator 34 by cold crimping. Taking into account the connection and mechanical strength requirements, the wire 19 of the winding 21 is then subjected to a second, hot crimping.

[0064] As seen in Figure 1, the commutator 34 is fitted onto the rotor shaft 12. Given the dimensions of the crimping tools and the presence of the cage 22, it is not possible to perform hot and cold crimping once the commutator has been fully fitted onto the rotor shaft 12. Therefore, these crimps are only performed when the commutator 34 is partially fitted onto the end 15 of the rotor shaft 10.

[0065] As a result, the applicant has observed that the recoil of the collector 34 during its final fitting onto the end 15 of the shaft 12 of the rotor 10 produces a loosening of the winding wire 19, particularly with regard to its input strand 30 which is the longest outside the poles 16, since this strand 30 is wound and guided in part around the body 36 of the rotor 34.

[0066] This loosening can be detrimental to the mechanical strength of the input strand 30 during the operation of the electric machine. Indeed, according to one possible explanation, due to its relative freedom, the input strand 30 is likely to be subjected to alternating accelerations and stresses as the rotor accelerates, which can eventually cause it to break and consequently stop the electric machine.

[0067] To remedy this drawback, according to the invention, the collector 34 includes at least one mounting tab 56 projecting from the body 36, specifically from the rear section 42 of the body 36. Without limiting the invention, this mounting tab 56 is also radial. This mounting tab 56 is intended to be positioned between the end 50 of the wire 19 and the winding 21, and is suitable for being fixed to said winding wire 19.

[0068] This configuration allows, during assembly, regardless of the relative position of the first connecting tab 46 and the mounting tab 56, the input strand 30 of the wire 19 to be received simultaneously in the first connecting tab 46 and the mounting tab 56, then the end 50 of said winding wire 19 to be fixed only to whichever of said tabs 46, 56 is closest to said end 50, then the winding wire 19 to be mechanically tensioned between said tabs 46, 56, before being fixed to the other of said tabs 46, 56. It will be understood that, since the input strand 30 of the wire 19 is received simultaneously in the first connecting tab 46 and the mounting tab 56, in order to achieve tension the end 50 of the winding wire 19 is necessarily fixed to whichever of the tabs 46, 56 is closest to said end 50.

[0069] This tension on the first strand 30 of the winding wire 19 is capable of compensating for the slack in the winding wire 19 during the retraction of the commutator 34 when it is finally fitted onto the rotor shaft 12. This tension on the wire 19 therefore eliminates the risk of the input strand 30 flapping.

[0070] In the embodiment shown in the figures, the two tabs 46, 56 receiving the wire 19, it is the fixing tab 56 which is closest to the end 50 of the input strand 30 of the wire 19 and it is therefore the fixing tab 56 which is able to be fixed to the wire 19 upstream of the first connection tab 46. The first connection tab 46 is therefore located downstream of the fixing tab 56 when moving away from the end 50 of the wire 19.

[0071] In practice, the end 50 of the wire 19 can be fixed to the fixing tab 56 and is therefore not free and does not protrude out of the fixing tab 56.

[0072] It will be understood that this configuration could be reversed and that it could be the first connecting leg 46 which would be arranged near the end 50 of the input strand 30 of the wire 19, and it is therefore to this that the wire 19 would be attached, the fixing leg 56 then being located downstream of the first connecting leg 46 when moving away from the end 50 of the wire 19.

[0073] As illustrated, the first connecting leg 46 and the fixing leg 56 are spaced angularly at a determined angle d configured to allow the passage between these legs 46, 56 of a squeezing tool 58 capable of squeezing the input strand 30 radially towards the body 36.

[0074] In the embodiment shown here, a excitation tool 58 is preferably used, comprising an active end 60, in particular a roller, having a groove 62 suitable for cooperating with the winding wire 19, as shown in the.

[0075] Thus, as illustrated, the rotor 10 can be assembled according to the following assembly process:

[0076] In a step i), the rotating collector 34 is partially fitted onto the end 15 of the shaft 12 of the rotor 10.

[0077] Then, in a step ii), the input strand 30 is inserted into the first radial connecting tab 46 and into the fixing tab 56 which are intended to receive the input strand 30, and only the one of said first connecting tab 46 and fixing tab 56 closest to the end 50 of the input strand 30 (i.e., generally receiving the end 50 of the input strand 30) is cold-crimped, i.e. in the example shown, the fixing tab 56.

[0078] Then during a step iii) the input strand 30 is placed in the guide means of the collector 34, that is to say on the collar 52 and the finger 54.

[0079] Then, in a step iv), the rotor wire 19 is wound onto the armature sectors of the poles 16. Then, in a step v) the output strand 32 of the wire 19 can be fixed by means of the second connection lug 48 which is preferably located at the same collector 34.

[0080] In step vi), the stress tool 58 is positioned in contact with the input strand 30 between the first connection lug 46 and the fixing lug 56. Then in step vii), the input strand 30 is stressed radially towards the body 36 of the collector 34 using the stress tool 58. The rotor equipped with its collector 34 is then moved to a hot crimping machine. By maintaining the tension, during a step viii) the input strand 30 is hot-crimped into the first connection lug 46 and, possibly, but not necessarily, into the fixing lug 56. As already mentioned above, such a hot crimping produces not only a fixing of the input strand of wire 19 in the first connection lug 46, or even in the fixing lug 56, but also an electrical contact between said wire 19 and said first connection lug 46, or even between said wire 19 and said fixing lug 56.

[0081] It should also be noted that only the first connecting tab 46 is necessarily connected to the input rotary contact 38. According to a first embodiment, in which the mounting tab 56 is also hot-crimped, said mounting tab 56 can also be connected to said input rotary contact 38. In another embodiment, it is not, or even not hot-crimped.

[0082] However, it should be noted that hot crimping, which is a resistance welding operation, also allows for strengthening a mechanical connection and that preferably both the first connection tab 46 and the fixing tab 56 will be hot crimped during step viii).

[0083] We can then in a step ix) release the stress on the input strand 30 by the stressing tool 58, and then in a step x) fully fit the rotating collector 34 onto the end 15 of the shaft 12 of the rotor 10.

[0084] It should be noted that, advantageously, during step v), the output strand 32 of the winding wire 19 is optionally fixed to the commutator by cold-crimping the end of the output strand 32 to at least the second connecting tab 48 receiving the output strand. This fixing is carried out or completed during step viii) by hot-crimping the output strand 32 of the winding wire 19 to at least the second radial connecting tab 48 receiving the output strand at approximately the same time as the first connecting tab 46, or even the fixing tab 56.

[0085] In the embodiment shown in Figure 1, the connection lugs 46 and the fixing lugs 56 of the input strand 30 are substantially radial overall, although this is not a limitation of the invention. In this embodiment, to secure the input strand 30 of the wire in the first connection lug 46 and in the fixing lug 56, each of the first connection lug 46 or fixing lug 56 comprises a main extension portion 64, 66, extending radially with respect to the axis A of the rotor 10. This main extension portion 64, 66 is, for example, bent at a right angle. Extending from this main extension portion 64, 66, each of the first connection lug 46 and fixing lug 56 comprises a wing 70, 72 extending from said portion 64, 66.Each wing 70, 72 is suitable for being folded over the input strand 30 in contact with the main extension part 64, 66 to fix said input strand 30 on said first connection tab 46 or on said fixing tab 56 by crimping.

[0086] Similarly, to secure the output strand 32 of the wire 19 in the second connecting tab 48, this tab 48 includes a main extension portion 68 extending radially with respect to the axis A of the rotor 10. This main extension portion 68 is, for example, also bent at a right angle. Extending from this main extension portion 68, the second connecting tab 48 includes a wing 74 which is adapted to be folded over the output strand 32 in contact with the main extension portion 68 to secure said input strand 32 to said second connecting tab 48 by crimping.

[0087] It will be understood that, in the same way as for the input strand 30, the collector 36 may include at least one fixing tab (not shown) also suitable for being fixed to the output strand 32, which would be arranged near the second connection tab 48 receiving the output strand 32, to ensure tension on the output strand 32 prior to its hot crimping.

[0088] The invention is particularly applicable to an electrical machine comprising at least one stator and one rotor 10 of the type described above.

Claims

Rotating commutator (34) for a rotor (10) of an electric machine, said commutator comprising: - a body (36) with axis A including at least one rotating contact (38), - at least one first connecting lug (46), projecting from the body (36), electrically connected to said at least one rotating contact (38) of said body (36), and adapted to be electrically connected and fixed to a winding wire (19) of the rotor, said commutator (34) comprising at least one mounting lug (56) projecting from the body (36), said mounting lug (56) being intended to be arranged between an end (50) of said wire and said winding, and adapted to be fixed to said winding wire, to allow successively receiving the wire (19) in the first connecting lug (46) and in the mounting lug (56), fixing the end (50) of said winding wire (19) only to that of said lugs (46, 56) which is closest to said end (50),mechanically tension the winding wire (19) between said lugs (46, 56), then fix it to the other of said lugs (46, 56). Rotating collector (34) according to the preceding claim, wherein the fixing tab (56) is able to be fixed to the end (50) of the wire (19) upstream of said first connection tab (46). Rotating collector (34) according to any one of the preceding claims, wherein the first connecting leg (46) and / or the fixing leg (56) comprises a main extension part (64, 66) and a wing (70, 72) extending from said part (64, 66), said wing (70, 72) being able to be folded over the wire (19) in contact with the main extension part (64, 66) to fix said wire (19) on said first connecting leg (46) and / or the fixing leg (56) by crimping. Collector (34) according to any one of the preceding claims, wherein the first connecting leg (46) and the fixing leg (56) are spaced a determined distance (d) configured to allow passage between said legs (46, 56) of a tool (58) capable of applying said wire (19) radially towards the body (36). Collector (34) according to any one of the preceding claims, wherein the first connecting lug (46) and the fixing lug (56) are fixed to a so-called input strand (30) of the wire (19) of the winding. Collector according to the preceding claim further comprising a second connection lug (48), intended to be fixed to a strand (32) called output strand of the wire (19) of the winding. Rotor (10) of an electric machine comprising at least: - a hub (13) of axis A, having a plurality of radial poles (16) arranged angularly at regular intervals around the axis (A), - a shaft (12) of axis A passing through said hub, coupled to said hub, and having one end (15) projecting out of said hub (13), - a continuous winding wire (19) wound on said poles (16), - the commutator (34) rotating according to any one of claim 5 or 6 fitted onto the end (15) of said shaft (12), and electrically connected at least to the input strand (30) of said continuous winding wire (19). electrical machine comprising at least one stator and one rotor (10) according to claim 7. A method for assembling a rotor (10) according to claim 7, comprising the steps of: i) partially fitting the rotating commutator (34) onto the end (15) of the rotor shaft (12), ii) inserting the input strand (30) into said first connecting tab (46) and said retaining tab (56) intended to receive the input strand, and cold-crimping the wire (19) only in said first connecting tab (46) and retaining tab (56) that is closest to the end (50) of said input strand (30), iii) positioning the input strand (30) in guiding means for the commutator (34), iv) winding the wire (19) from the rotor, v) securing the output strand (32) of the winding wire (19) to the commutator (34), vi) positioning a squeezing tool (58) in contact with the input strand (30) between said first connecting tab (46) and said fixing bracket (56),vii) apply radial stress to the input strand (32) towards the body (36) of the commutator (34) using said stress tool (58), viii) hot crimp the input strand (30) at least in said first connecting lug (46) and in the fixing lug (56), ix) release the stress on the input strand (30) by the stress tool (58), x) fully fit the rotating commutator (34) onto the end (15) of the shaft (12) of the rotor (10). Tool (58) for excitation for the implementation of a method according to claim 9, comprising an active end (60), in particular a roller, having a groove (62) adapted to cooperate with the winding wire (19).

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