Busbar for distribution of power between a wound rotor and a contactless excitation system

Abstract

The invention relates to a power distribution busbar (4) for an electric motor for a motor vehicle, the busbar being intended to be interposed between a ball bearing (6) and a mechanical shaft (5) of the electric motor. It comprises a far end (9) equipped with means for connecting the power distribution busbar to a system (3) for contactless excitation of a wound rotor (2) of an electric motor, a near end (10) equipped with means for connecting the power distribution busbar to a wound rotor (2) of an electric motor, one or more branches (11, 12), and electric wires (13) inserted into axial passages produced in the branches (11, 12), making it possible to make electric contact between the contactless excitation system (3) and the wound rotor (2).

Description

Description Title of the invention: Electrical power supply bus between a rotor coil and a contactless excitation system Technical field

[0001] The present invention relates to the electrical supply of wound rotors of motor vehicle electric motors and relates in particular to the connection between a wound rotor and an excitation system of an electric motor. More particularly, the invention relates to the electrical connection of a wound rotor and a contactless excitation system.

[0002] A contactless excitation system for a wound rotor performs the same function as an excitation system for an electric motor comprising a rotating commutator with a slip ring and brushes. Their function is to provide electrical power to the wound rotor. However, in a rotating commutator, the brushes rub continuously against the slip rings, which causes wear on the brushes and slip rings. A contactless excitation system thus avoids friction and therefore the risk of wear on the brushes on the rotating slip ring commutator of an electric motor.

[0003] In the automotive field, there are very few applications of wound rotor motors, and the use of a contactless excitation system for a wound rotor is very rare, if not non-existent. Although advantageous for limiting wear risks, such a system requires a connection to the wound rotor in order for it to be electrically powered. Statement of the invention

[0004] The invention relates to a power supply bus for an electric motor of a motor vehicle, the bus being intended to be interposed between a ball bearing and a mechanical shaft of the electric motor. It comprises a distal end provided with means for connecting the power supply bus with a contactless excitation system of a wound rotor of an electric motor, a proximal end provided with means for connecting the power supply bus with a wound rotor of an electric motor, one or more branches, and electrical wires inserted into axial passages made in the branches, making it possible to establish electrical contact between said contactless excitation system and said wound rotor.

[0005] The power bus is configured to be interposed radially between the ball bearing and the mechanical shaft, the mechanical shaft being grooved to immobilize the power bus from rotation.

[0006] Optionally, the power bus is created by overmolding and includes thermoplastic.

[0007] Advantageously, electrical wires protrude from each end, forming connection hooks.

[0008] According to one embodiment, a first connection hook is in contact with the electrical cables of the contactless excitation system, the contact being made by soldering, crimping or using terminals.

[0009] According to one embodiment, a second connection hook is in contact with the electrical cables of the wound rotor, the contact being made by welding, crimping or using terminals.

[0010] Advantageously, the supply bus comprises a guide surface capable of recovering and directing, by centrifugation, a portion of a lubricating liquid towards the contactless excitation system, in particular to cool it.

[0011] Optionally, the guide surface has a truncated cone shape.

[0012] The invention also relates to an electric motor comprising a power supply bus as defined above.

[0013] The invention also relates to a motor vehicle comprising a power supply bus as defined above. Brief description of the drawings

[0014] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0015] - [Fig.l] is a partial schematic view of an electric motor of a motor vehicle equipped with a power bus connected to a contactless excitation system and to a wound rotor;

[0016] - [Fig.2] is a partial sectional view of an electric motor of a motor vehicle equipped with a power bus positioned on a mechanical shaft; and

[0017] - [Fig.3] is a partial schematic view of an electric motor of a motor vehicle equipped with a power bus positioned on a mechanical shaft. Detailed description

[0018] In [Fig.l], there is shown a part of an electric motor of a motor vehicle with at least partially electric traction, designated by the general numerical reference 1.

[0019] The motor comprises a wound rotor 2, a contactless excitation system 3 for the wound rotor 2 and a power supply bus 4 providing electrical power to the rotor 2 from the excitation system.

[0020] The wound rotor 2 is carried by a mechanical shaft 5 bearing on bearings, such as the ball bearing 6, lubricated by a lubrication circuit.

[0021] The excitation system 3 is intended to electrically supply the wound rotor 2. It includes in particular an excitation part 7 fixed to the casing of the electric motor and intended to recover an electric current, and a rectifier circuit 8 intended to transmit the electric current to the wound rotor 2 via the power supply bus 4.

[0022] The power bus 4 is configured to radially surround the shaft 5, and more precisely to be interposed between the shaft 5 and the bearing 6.

[0023] The power bus 4 comprises a distal end 9, provided with means for connecting the power bus 4 with the contactless system 3 of the wound rotor 2, a proximal end 10, provided with means for connecting the power bus 4 with the wound rotor 2, and one or more branches 11, 12, in which axial passages are made. The power bus 4 also comprises electrical wires 13 inserted into the axial passages of the branches 11, 12 making it possible to establish electrical contact between the wound rotor 2 and the contactless system 3. The branches 11, 12 therefore make it possible to transport electricity from the distal end 9 to the proximal end 10 via the electrical wires 13.

[0024] [Fig. 2] illustrates the fitting of the power bus 4 onto the shaft 5. The latter comprises grooves 14 which accommodate the branches 11, 12 of the power bus 4 in order to immobilize it in rotation. The branches 11, 12 therefore also have the objective of immobilizing the power bus 4.

[0025] According to one embodiment, the power supply bus 4 comprises a radial support at the proximal end 10, making it possible to hold the branches 11, 12.

[0026] The electrical wires 13 protrude from each end 9, 10, forming connection hooks 9a, 9b, 10a, 10b.

[0027] As illustrated in [Fig. 1], on the side of the distal end 9, the electrical wires 13 form one or more first connection hooks 9a, 9b and, on the side of the proximal end 10, the electrical wires 13 form one or more second connection hooks 10a, 10b.

[0028] According to one embodiment, these hooks 9a, 9b, 10a, 10b are metallic, for example copper-plated, conducting electric current.

[0029] The means for connecting the power supply bus 4 with the contactless system 3 of the wound rotor 2 therefore comprise first hooks 9a, 9b placed in contact with electrical cables Xa, Xb at the output of the rectifier 8. According to various embodiments, the contact between the hooks 9a, 9b and the electrical cables of the rectifier 8 is made by welding, by crimping or by using lugs.

[0030] The means for connecting the power supply bus 4 with the wound rotor 2 comprise second hooks 10a, 10b placed in contact with electric cables Ya, Yb of the coils of the wound rotor 2, shown in [Fig.2]. The contact between the hooks 10a, 10b and the electric cables of the wound rotor 2 is made, for example, by welding, by crimping or by using terminals.

[0031] In other words, the electric cables Xa, Xb, Ya, Yb are, for example, wound respectively around the hooks 9a, 9b, 10a, 10b, or welded or crimped respectively to the hooks 9a, 9b, 10a, 10b.

[0032] These contacts thus make it possible to electrically connect the wound rotor 2 and the excitation system 3.

[0033] Advantageously, the power bus 4 is overmolded and comprises thermoplastic.

[0034] The power bus 4 also comprises a radial guide surface 15 visible in [Fig. 3]. This guide surface 15 recovers a lubricating liquid downstream of the bearing 6 and is configured to direct this lubricating liquid towards the excitation system 3. This guide surface 15 thus makes it possible to cool the non-contact excitation system 3, which heats up quickly, more quickly and over a larger area.

[0035] In various embodiments, the guide surface 15 may have different shapes, as long as this shape allows the centrifugation of the lubricating liquid towards the excitation system 3. For example, the guide surface 15 has a truncated cone shape.

[0036] When the wound rotor 2 is electrically powered, the assembly comprising the wound rotor, the shaft 5 and the power bus 4 is rotated with the rectifier circuit 8 of the excitation system 3. While these parts are rotating, the excitation part 7 of the contactless excitation system 3 is stationary, fixed to the casing of the electric motor.

Claims

Claims

1. Power supply bus (4) for an electric motor of a motor vehicle, said bus being intended to be interposed between a ball bearing (6) and a mechanical shaft (5) of the electric motor, characterized in that it comprises a distal end (9) provided with means for connecting the power supply bus with a contactless excitation system (3) of a wound rotor (2) of an electric motor, a proximal end (10) provided with means for connecting the power supply bus with a wound rotor (2) of an electric motor, one or more branches (11, 12), and electrical wires (13) inserted in axial passages made in the branches (11, 12), making it possible to establish an electrical contact between said contactless excitation system (3) and said wound rotor (2).

2. Power bus (4) according to claim 1, configured to be interposed radially between the ball bearing (6) and the mechanical shaft (5), said mechanical shaft (5) being grooved to immobilize the power bus (4) in rotation.

3. Power bus (4) according to one of claims 1 and 2, created by overmolding and which comprises thermoplastic.

4. Power bus (4) according to any one of claims 1 to 4, wherein the electrical wires (13) protrude from each end (9, 10) forming connection hooks (9a, 9b, 10a, 10b).

5. Power supply bus (4) according to any one of claims 1 to 5, configured so that a first connection hook (9a, 9b) is in contact with the electrical cables (Xa, Xb) of the contactless excitation system (3), said contact being made by soldering, crimping or using terminals.

6. Power bus (4) according to any one of claims 1 to 6, configured so that a second connection hook (10a, 10b) is in contact with the electrical cables (Ya, Yb) of the wound rotor (2), said contact being made by soldering, crimping or using terminals.

7. Power supply bus (4) according to any one of claims 1 to 7, which comprises a guide surface (15) capable of recovering and directing, by centrifugation, a portion of a lubricating liquid towards the contactless excitation system (3), in particular to cool it.

8. A power bus (4) according to claim 8, wherein the guide surface (15) has a truncated cone shape.

9. An electric motor comprising a power bus (4) according to any one of claims 1 to 9.

10. Motor vehicle comprising a power supply bus (4) according to any one of claims 1 to 9.

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