Slip ring for a wound rotor and rotor assembly comprising same

Abstract

The invention relates to a slip ring (C') configured to be securely mounted on the shaft of a wound rotor for a rotary electric machine and to be connected to the winding of the rotor, the slip ring comprising a current-collecting part (10), at one end of the slip ring, which is able to be connected to an electrical energizing system, characterized in that said current-collecting part (10) is removable and comprises elements (103, 104) for reversible electrical connection with the remaining part of the collector (10'). It also relates to a wound rotor assembly comprising said slip ring and to the process for manufacturing said assembly.

Description

Description Title of the invention: Rotating electrical collector of a wound rotor and rotor assembly comprising it

[0001] The invention relates to a rotating electrical collector of a wound rotor intended for a rotating electrical machine. It also relates to a wound rotor assembly comprising said rotating electrical collector, and the method of manufacturing the rotor assembly. It also relates to a vehicle comprising a rotating electrical machine comprising the wound rotor assembly.

[0002] Rotating electrical machines comprise a stator and a rotor secured to a shaft. The rotor may be secured to a driving and / or driven shaft and belong to a rotating electrical machine such as an electric motor or an alternator. The rotating electrical machine may be used in reversible operation in motor mode (electric current receiver) and in current generator mode, for example in the case of traction of a vehicle by an electric motor connected to a battery of electrochemical accumulators and which may operate as a current generator using for example regenerative braking, that is to say by using the inertia of the vehicle to drive the electric machine to enable the battery to be charged.

[0003] In the remainder of the description, the shaft to which the rotor is attached is called the “rotor shaft”.

[0004] Slip rings are electrical components used to create an electrical connection between a fixed part of a rotating electrical machine (electrical excitation system) and the rotor, the rotating part of the rotating electrical machine. They are used in particular in the case of rotation of a wound rotor, where transmission of electric current by cable would be impossible.

[0005] Figure 1A illustrates a wound rotor provided with a rotating electrical commutator “C”, and Figure 1B illustrates the commutator alone “C” according to a prior art. The rotating electrical commutator “C” is a rotating ring commutator.

[0006] Generally, a rotating ring collector comprises a support made of electrically insulating material having a spacer (electrically insulating) around which is fixed at least one electrically current-conducting collector ring, generally made of copper, the support with the spacer being mounted around the rotor shaft. In addition, connection elements made of electrically conductive material are secured to said collector support to provide the connection between the rotor winding and one end of the collector which is connected to the collector ring(s) of the collector. Furthermore, an electrical connection is established between the ring(s) and an electrical excitation system (of the fixed part of the electric machine) by sliding mechanical contact. This electrical connection can be established by means of an electrically conductive brush (not shown in the figures) which rubs on the rotating collector ring, or if necessary by means of a flexible metal blade in the case of very small electric machines. This is how the rotor is permanently supplied with an electric current which creates a magnetic field.

[0007] According to the example illustrated in Figure 1A, the rotor R comprises coils B of electrically conductive wire covered with electrically insulating enamel, which, in the case of an electric motor, must be supplied with electric current in order to generate a magnetic field and create a driving torque rotating the shaft A of the rotor. The coils are connected in series according to the example. At the end of the rotating collector proximal to the coils are two electrical connection elements C1, C2, made of electrically conductive material, respectively receiving the connection of one of the ends B1, B2 of the rotor winding, one of the hooks corresponding to the positive pole and the other hook to the negative pole. The ends of the rotor winding are fixed and electrically connected to the connection hooks for example by hot crimping which melts the insulating enamel. The collector comprises two current collector rings C11, C12, which are respectively connected to one of the connection hooks C1, C2 by a dedicated internal electrically conductive connection. This electrically conductive connection comprises, for example, a metal strip extending from a hook to one of the rings.

[0008] The design of current rotors creates problems. A problem is encountered during the manufacture of the rotor which includes a step of impregnating the rotor winding with a resin to fix the turns of the winding so that the winding is correctly held in place during rotation of the rotor in particular. The impregnation requires a step of baking the impregnation resin, which causes an oxidation deposit on the electrically conductive rings, especially when they are made of copper. The consequence is poor conductivity and therefore poor power supply to the rotor, which can cause failures of the electric motor for example. Another problem arises from the wear of the collector, in particular due to the wear of the rings, it is necessary to dismantle and change the entire rotor - collector assembly, the collector being connected in a non-reversible manner with the ends of the rotor winding.

[0009] Furthermore, rotating electrical machines may comprise a wound rotor connected to a contactless excitation system by means of a rotating electrical commutator without sliding mechanical contact with the contactless excitation system (brushless). This rotating commutator may be electrically connected on the one hand to the rotor winding and on the other hand to a rotating part of the excitation system which rotates integrally with the rotor shaft and which supplies the rotor with direct current. The electrical connections of the commutator with the rotor and with the rotating part of the excitation system are permanent (non-reversible). A problem in the event of an incident with the collector is the need to dismantle the wound rotor with the current collector. Furthermore, depending on the configuration and nature of the collector connection elements with the excitation system, these elements could also be altered during the impregnation step of the rotor winding.

[0010] The invention aims to address these issues.

[0011] To this end, the invention provides a rotating current collector configured to be securely mounted to the shaft of a wound rotor for a rotating electrical machine and to be connected to the winding of the rotor, and said collector comprising a current collecting part, at one end of the collector, capable of being connected to an electrical excitation system. According to the invention, said current collecting part is removable and comprises elements for reversible electrical connection with the remaining part of the collector.

[0012] Said collector part at one end of the collector can thus be removed from the collector if necessary when the collector is installed on the rotor shaft and connected to the rotor winding, without having to remove the entire assembly, and therefore without having to change the entire assembly, the collector remaining connected to the rotor only by its remaining part. The invention thus presents an economic advantage by saving time and simplifying the repair process for the user.

[0013] According to a particular embodiment of the invention, said remaining part of the collector comprises first electrical connection means capable of being connected directly to the winding of the rotor and second electrical connection means connected to said first connection means and reversibly connecting with the connection elements of the removable collector part.

[0014] More particularly, said remaining part of the collector comprises an electrically insulating support of elongated shape, and said first electrical connection means capable of being connected directly to the winding of the rotor are external connection elements with respect to said support, and said second electrical connection means are electrically conductive elements which have an elongated shape extending into said support to be reversibly connected to the removable part of the collector. Preferably, said first external electrical connection means are carried at one end of the support and said second electrical connection means extend at least to the end of said support opposite to that carrying the first connection means, to be reversibly connected to the removable part of the collector. In particular, said electrically insulating support has a generally cylindrical elongated shape.

[0015] According to a particular embodiment of the invention, said removable current collector part comprises at least one current-conducting ring (collector ring) capable of being connected by sliding mechanical contact to the excitation system, in particular via an electroconductive component of the brush type.

[0016] According to another particular embodiment of the invention, said removable current collector part is configured to be connected with an excitation system without sliding mechanical contact. In particular, the removable collector part of the rotating collector is configured to be connected by a mechanical contact to a rotating part that comprises the excitation system which can rotate integrally with the rotor shaft and which can supply the rotor with direct current.

[0017] The invention also relates to a wound rotor assembly for a rotating electrical machine comprising the rotor shaft and a rotating current collector mounted around said rotor shaft, said rotating current collector being as described above, the removable current collector part being reversibly connected to the remaining part of the collector which is connected to the rotor winding.

[0018] The invention also relates to a method of manufacturing a wound rotor assembly for a rotating electrical machine, comprising the rotor shaft and a rotating current collector mounted around the rotor shaft, in which a current collector as described above is used, and comprising the following steps which ones - (a) the current collector is mounted around the rotor shaft without the removable collector part, and the rotor winding is connected to the remaining part of the current collector mounted around the rotor shaft, then - (b) the rotor winding is impregnated with a resin, then (c) thermosetting said resin, then - (d) the removable collector part of said current collector is mounted around the rotor shaft and reversibly connected to the remaining part of the current collector.

[0019] The current collector according to the invention thus allows an advantageous manufacturing process for the wound rotor assembly without fear of altering the collector part which will be connected to the excitation system.

[0020] In particular, the remaining portion of the current collector and the removable collector portion of the current collector are mounted respectively in step (a) and step (d) by press-fitting around the rotor shaft.

[0021] In particular, in step (d), the removable collector part of the rotating electrical collector is mounted butted against the remaining part of the collector.

[0022] The invention also relates to a rotating electrical machine comprising the wound rotor assembly as described above or a wound rotor assembly manufactured according to the method as described above. In particular, said machine is configured to operate as an electric current receiver and as an electric current generator.

[0023] The invention also relates to a vehicle, in particular a motor vehicle, comprising a rotating electrical traction machine which comprises a wound rotor assembly as described above or a wound rotor assembly manufactured according to the method as described above. Advantageously, said machine is configured to operate as a receiver of electric current and as a generator of electric current, for example to enable the energy source of the excitation system to be recharged. In generator mode, for example, the inertia of the vehicle can be used to drive the electric machine in order to charge a battery.

[0024] Other features and advantages of the invention will emerge from reading the description given below of a particular embodiment of the invention, given for informational purposes but not as a limitation, with reference to the appended drawings in which:

[0025] [Fig. 1 A] illustrates, in a perspective view, a rotating electrical collector mounted on the shaft of a wound rotor, according to a prior art embodiment of the invention.

[0026] [Fig. 1 B] is a perspective view of the rotating electrical collector of Fig. 1A according to a prior art.

[0027] [Fig. 2] is a perspective view of a rotating electrical collector according to one embodiment of the invention.

[0028] [Fig. 3] is a view of a portion of the rotating electrical collector shown in Figure 2.

[0029] [Fig. 4] is a partial view, in longitudinal section, of the rotating electrical collector of Figure 3.

[0030] Figures 1 A and 1 B were commented on in the introduction.

[0031] Figures 2 to 4 illustrate a rotating electric current collector according to an embodiment in accordance with the invention capable of being connected to a wound rotor. Said collector is a rotating ring collector “C'”.

[0032] The rotating current collector “C'” consists of two separable parts 10, 10', in other words the collector comprises two parts.

[0033] The collector thus comprises a first part, the part 10' connected directly to the rotor winding. It comprises an electrically insulating support 100', made of plastic material, of elongated, generally cylindrical shape (axial direction XX') and internally hollow. The plastic material is a thermoplastic, a polyamide according to the example. This first part (part 10') comprises first connection elements 11, 12, receiving the ends of the rotor winding, and which are external to said support 100' which supports them at its end which will be proximal to the rotor winding. These first connection elements 11, 12 are in the form of hooks in which the ends of the rotor winding will be hot-crimped to establish electrical contact.These hooks 11, 12 are furthermore connected to second connection elements 111, 112, internal to said support 100', and which extend to the end of the support which is opposite the end carrying the external connection elements 11, 12 (see Fig. 4).

[0034] The collector also comprises a second part 10, corresponding to the current collector part 10 of the collector, capable of being connected to an electrical excitation system with sliding mechanical contact of the fixed part of a rotating electrical machine. It comprises two electrical current collector rings 101, 102, made of electrically conductive material, copper according to the example, fixed around an electrically insulating support 100, of cylindrical and hollow shape (in axial direction XX') which is installed as an insulating spacer on the rotor shaft. The rings 101, 102 will thus establish an electrical connection with an electrical excitation system via brushes.

[0035] Said current collector part 10 also comprises two elements of connection 103, 104, partially internal to its electrically insulating support 100, which are on the one hand connected respectively to a ring 101, 102, and on the other hand connected, reversibly, respectively to the second internal connection elements 111, 112 of said first part 10' by ends protruding from the support 100. The connection between the respective connection elements 103, 104, 111, 112 of the two parts 10, 10' of the collector is made by pressing electroconductive strips between them, according to the example (Fig. 4).

[0036] When manufacturing the wound rotor assembly comprising the wound rotor, the rotor shaft and the rotating current collector C', the following procedure is carried out: - the first part 10' of the current collector is mounted alone around the shaft of the wound rotor, and the ends of the rotor winding are then connected respectively to the external connection elements 11, 12 of said first part 10', then - the rotor winding is impregnated with a resin, where appropriate including the connections with the external elements 11, 12 of the part 10' of the collector, then - the said resin is thermoset, in order to hold the turns of the winding together and ensure the winding holds during rotations, then - the second part 10, the ring collector part of the collector, is mounted around the rotor shaft so as to abut it with the first part 10' of the collector and to connect its partially internal connection elements 103, 104, reversibly, respectively to those internal 111, 112 of said first part 10'.

[0037] The impregnation resin is chosen from resins known per se for this use.

[0038] The different parts 10, 10' of the current collector are mounted around the rotor shaft by press-fitting (shrink fitting) according to the example.

[0039] The collector part 10 which connects to the electrical excitation system is therefore installed on the collector mounted on the rotor in a removable manner. It can be easily separated from the first part 10 of the collector, which is the remaining part of the collector connected (permanently) directly to the rotor winding. In the event of wear, only this removable part 10 needs to be replaced.

[0040] Furthermore, the wound rotor assembly, which includes the wound rotor, the rotor shaft and the rotating commutator, can be manufactured without the commutator part 10 with ring being subjected to the impregnation step which can oxidize it.

[0041] The invention is however not limited to the embodiment described, in particular not to the method of electrical connection between the two parts of the rotating collector which has been described. An electrical connection by clipping, for example using electrical terminals and / or electrical connectors, can be envisaged. In addition, the method of joining the two parts and their mounting on the rotor shaft is not limited to a method of butting by shrink-fitting the two parts onto the rotor shaft.

[0042] The invention can thus be applied to a rotating electrical machine of the electrical receiver type, for example an electric motor, or of the electrical generator type, as well as to a rotating electrical machine required to use both current receiver and generator functions, such as for example an electric motor of a vehicle powered from a battery.

Claims

Claims

1. Rotating current collector (C') configured to be mounted securely to the shaft of a wound rotor for a rotating electrical machine and to be connected to the winding of the rotor, and said collector comprising a current collecting part (10), at one end of the collector, capable of being connected to an electrical excitation system, characterized in that said current collecting part (10) is removable and comprises reversible electrical connection elements (103, 104) with the remaining part of the collector (10').

2. Rotating current collector according to claim 1, characterized in that said remaining part of the collector (10') comprises first electrical connection means (11, 12) capable of being connected directly to the rotor winding and second electrical connection means (111, 112) connected to said first connection means (11, 12) and reversibly connecting with the connection elements (103, 104) of the removable collector part (10).

3. A rotating current collector according to claim 2, characterized in that said remaining part of the collector (10') comprises an electrically insulating support (100') of elongated shape, and in that said first electrical connection means (11, 12) capable of being connected directly to the rotor winding are external connection elements (11, 12) with respect to said support (100'), and in that said second electrical connection means (111, 112) are electrically conductive elements which have an elongated shape extending into said support (100') to reversibly connect to the removable part (10) of the collector.

4. Rotating current collector according to one of claims 1 to 3, characterized in that said removable current collector part (10) comprises at least one current-conducting ring (101, 102) capable of being connected by sliding mechanical contact to the excitation system.

5. Rotating current collector according to one of claims 1 to 3, characterized in that said removable current collector part is configured to be connected with an electrical excitation system without sliding mechanical contact.

6. A wound rotor assembly for a rotating electrical machine comprising the rotor shaft and a commutator rotating current (C') mounted around said rotor shaft, characterized in that said rotating current collector is according to any one of claims 1 to 5, the removable current collector part (10) being reversibly connected to the remaining part of the collector (10') which is connected to the rotor winding.

7. A method of manufacturing a wound rotor assembly for a rotating electrical machine, comprising the rotor shaft and a rotating current collector mounted around the rotor shaft, in which a current collector (C') according to one of claims 1 to 5 is used, and comprising the steps of - (a) the current collector is mounted around the rotor shaft without the removable collector part (10), and the rotor winding is connected to the remaining part (10') of the current collector mounted around the rotor shaft, then - (b) the rotor winding is impregnated with a resin, then - (c) said resin is thermoset, then - (d) the removable collector part (10) of said current collector is mounted around the rotor shaft and reversibly connected to the remaining part (10') of the current collector.

8. A method of manufacturing a wound rotor assembly according to claim 7, characterized in that the remaining part (10') of the current collector and the removable collector part (10) of the current collector are mounted respectively in step (a) and in step (d) by fitting around the rotor shaft.

9. Method of manufacturing a wound rotor assembly according to one of claims 7 to 8, characterized in that in step (d), the removable collector part (10) of the rotating electrical collector is mounted butting against the remaining part of the collector (10').

10. Vehicle, in particular motor vehicle, comprising a rotating electrical traction machine which comprises a wound rotor assembly according to claim 6 or a wound rotor assembly manufactured according to the method according to one of claims 7 to 9, and preferably said machine being configured to operate as an electric current receiver and as an electric current generator.

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