Device for supplying electric current to the rotor of an electric machine.

Abstract

Current supply device 10 for the rotor of an electrical machine consisting of: a first fixed element 200, made of insulating material, composed of a radial face 202, a tubular part 201 carrying ears 203 for fixing to a casing 40 using screws 45 and centered on a shoulder 41 of the casing 40 by an internal diameter 201a; a second fixed element 300, made of insulating material, centered in the first fixed element 200; a rotary element 100, made of insulating material, carried by a rotor shaft 20; two current transmitting discs 400 interposed between the fixed elements and the rotary element; characterized in that in the tubular part 201 of the fixed element 200 the rotary element 100 is arranged between the radial face 202 and the second fixed element 300 and all of the components are brought into contact and under pressure by a corrugated washer 320 pushing on the second fixed element 300 while bearing on the first fixed element 200. Figure for the abstract: Fig.1

Description

Title of the invention: Device for supplying electric current to the rotor of an electric machine. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an electric current supply device comprising a rotating central element, connected to the terminals of the coils of the rotor of an electric machine, framed and enclosed by two fixed elements connected to a direct or alternating current electric supply external to the electric machine. STATE OF THE ART

[0002] the power supply of the rotor coils of an electrical machine uses a device comprising two friction contacts between rotating elements, rings generally made of copper also called collectors, carried by an insulating ring arranged on the rotor shaft, connected to the rotor coils and fixed elements, the brushes, also called "carbons" because of the high proportion of carbon, carried by an insulating structure fixed to the casing of the electrical machine.

[0003] Wound rotor electric machines have been adopted by very few electric car manufacturers.

[0004] However, this type of machine has the advantage of not requiring permanent magnets and therefore rare earths and the magnetic field generated by the rotor coils is adjustable.

[0005] On the other hand, the current supply of the coils has disadvantages: - an increase in the length of the machine; - the need to create a sealed chamber because the wear of the brushes releases dust; - wear of the brushes which may require maintenance; - small diameter collector rings to limit speed tangential contact with the brushes.

[0006] This last drawback obliges us to associate with the motor a conventional reducer with a remote differential. The small diameter rings do not, in fact, allow the association of the electric machine with a coaxial reducer, advantageous in packaging, because one of the transmission shafts, whose diameter is of the order of 25 to 30 mm, passes through the hollow shaft of the rotor. However, the external diameter of the collector rings is of the same order of magnitude as that of the transmission shaft.

[0007] A means of transmitting current other than the friction of a brush is known. This is conduction by the contact of a rolling body on a fixed body.

[0008] This is the method used for electric traction on rails. The motor of an electric train is supplied with energy by the single conductor cable of a catenary. The machine is subject to the potential difference between the catenary and the ground. The connection between the electric traction machine and the ground is made via the chassis, the bogie axle, the wheels and the rails. A brush device provides the electrical connection between the axle and the wheels in order to protect the wheel bearings. Such a device is described in publication EP 2 724 913.

[0009] A device for transmitting current by a rotating contact is described in publication FR 2 124 728 (utility certificate of 1972) entitled “rotating electrical contact”. The device is similar to an angular contact ball bearing whose inner and outer sheet metal rings each have a terminal and are insulated from the shaft and the housing. PRESENTATION OF THE INVENTION

[0010] The present invention relates to the supply of current to the coils of an electric machine rotor by two contacts, supply and return of the electric current, comprising the rolling bodies.

[0011] The rolling bodies are positioned on a diameter large enough to allow the production of a hollow rotor shaft and the passage of the transmission shaft of a coaxial type reducer.

[0012] However, the current transmitted by a rolling body must remain of low intensity so as not to cause an electric arc to appear which could damage the rolling body itself and its raceways. The solution is to multiply the rolling bodies, each transmitting, in parallel, a small fraction of the current.

[0013] The device, object of the invention, comprises a central element made of insulating material mounted on the rotor shaft, driven in rotation by grooves, serving as a support for two crown-shaped plates made of conductive material, copper or copper alloy, and each of these plates has on the inner periphery, a tongue for driving in rotation by the central element and on which is welded an electrically conductive wire for connection with the rotor coils.

[0014] The device comprises a first fixed element, made of insulating material, of tubular shape surrounding the rotating central element, which has at one end a radial face which carries a crown-shaped plate made of conductive material, which has, on the outer periphery, a tab making it fixed like its supporting element and on which is welded an electrically conductive wire for connection to the external electrical supply.

[0015] The device comprises a second fixed element made of insulating material closing the first hollow fixed element and thus forming a chamber containing the rotating element. This second The fixed element also carries a crown-shaped plate made of conductive material. This has, on the outer periphery, a tab making it fixed like its supporting element and on which is welded an electrically conductive wire for connection to the external power supply.

[0016] Between the conductive crown-shaped plate of the first fixed element and one of the crown-shaped plates of the rotating element is interposed an annular disc made of insulating or non-insulating material, carrying rolling bodies made of conductive material, copper or copper alloy, responsible for making a first electrical connection between the two crown-shaped plates.

[0017] Between the conductive crown-shaped plate of the second fixed element and the other crown-shaped plate of the rotating element, there is also interposed an annular disc, identical to the previous one, made of insulating material or not, carrying rolling bodies made of conductive material, copper or copper alloy, responsible for making a second electrical connection between the two crown-shaped plates.

[0018] The second fixed element has an excess thickness at its periphery, the internal diameter of which accommodates a spring of the corrugated washer type, put under tension by a flat washer stopped by a ring housed in a groove of the first fixed element, which allows axial pressure to be applied to all of the elements and guarantees permanent contact of the rolling bodies with the two tracks. DETAILED DESCRIPTION OF THE INVENTION

[0019] These characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows and with regard to the appended drawings given as non-limiting examples and in which:

[0020] [Fig. 1] is a sectional view of the entire device mounted on the rotor shaft;

[0021] [Fig.2] is a front view of the annular transmitting disc supporting bodies rolling and a cut according to AA;

[0022] [Fig.3] is a sectional view of the entire device passing through the first fixed connection and the BB cut in the plane of the conductive crown-shaped plate;

[0023] [Fig.4]is a sectional view of the entire device passing through the second fixed connection and the CC section in the plane of the conductive crown-shaped plate;

[0024] [Fig.5]is a front view of the device on the fixing side on the casing showing the output of the two fixed conductors;

[0025] [Fig.6]is a sectional view of the entire device passing through the first rotary connection and the DD section in the plane of the conductive crown-shaped plate;

[0026] [Fig.7] is a sectional view of the entire device passing through the second rotary connection and the section EE in the plane of the conductive crown-shaped plate;

[0027] [Fig.8]is a front view of the device from the side opposite the fixing face and showing the output of two rotating conductors.

[0028] [Fig. 1] shows in section the entire device 10 carried by the hollow rotor shaft 20. It is composed of a first fixed element 200, made of insulating material, containing, in its tubular part 201, the other components of the device 10.

[0029] This fixed element 200 has around its tubular part 201 ears 203 for fixing to the casing 40 of the electric machine by the screws 45. It is centered by its internal diameter 201a on the shoulder 41 of the casing.

[0030] Opposite the fixing face, the first fixed element 200 is partially closed by a radial face 202 open in its center.

[0031] On the internal side of the radial face 202 is fixed, for example by gluing, a crown-shaped plate 210 made of conductive material, preferably copper or copper alloy.

[0032] Inside this first fixed element 200 is arranged a rotary element 100 having a cylindrical part 101 and a discoid part 102.

[0033] The rotary element 100, carried by the rotor shaft 20, has drive splines 101a, cooperating with the splines 21 of the rotor shaft. This rotor shaft 20 is guided by the ball bearing 30, stopped on the shaft by the stop ring 32 and placed under slight preload by the elastic washer 31 arranged between its outer ring and the casing 40.

[0034] The rotating element 100 carries on either side of its discoid part 102 two crown-shaped plates 110 and 120, made of conductive material, preferably copper or copper alloy.

[0035] A second fixed element 300 encloses the rotary element 100 in the first fixed element 200. This second fixed element 300 is mainly in the form of a disc with a cylindrical part 302 at its periphery centered by its external diameter 302a in the first fixed element 200.

[0036] Internally, the fixed element 300 has an excess thickness 301. This excess thickness, open in its center, allows the rotor shaft 20 to pass freely and its external diameter centers the crown-shaped plate 310, made of conductive material, preferably copper or copper alloy.

[0037] Between the crown-shaped plates 110 rotating and 210 fixed on the one hand, 120 rotating and 310 fixed on the other hand are interposed transmitting discs 400 free to rotate and centered by the external diameter with a significant clearance in the part tubular 201 of the first fixed element 200 and by the internal diameter with a significant clearance in the cylindrical part 101 of the rotating element 100.

[0038] The cylindrical part 302 accommodates an elastic corrugated washer 320 centered in the internal diameter 302b. This corrugated washer 320 is tensioned by the washer 321 stopped by the stop ring 322, implanted in a groove cut in the diameter 201a of the first fixed element 200.

[0039] This corrugated washer 320, resting on the first fixed element 200, presses the second fixed element 300 onto the transmitter disc 400, itself put under pressure on the rotating element 100, itself put under pressure on the second transmitter disc 400, pressed onto the crown-shaped plate 210. This thus ensures the best possible transmission of the electric current between the facing crown-shaped plates 110, 210 and 120, 310.

[0040] [Fig.2] is a front view of the transmitter disc 400. It is similar to a needle thrust bearing, but plays a very different role. It is composed of an annular disc 401 made of insulating or metallic material (preferable for mechanical strength) which has, on a circle, a large number of rectangular openings in which are inserted rollers 402, all identical cylindrical, made of conductive material, copper or copper alloy, with a diameter greater than the thickness of the annular disc 401.

[0041] The choice of a very large number of rollers 402 is the way of sharing the electric current and limiting it, for each contact, to a low intensity level reducing the risks of electric arcing and damage.

[0042] The choice of short cylindrical rollers is the way to limit sliding friction because the ends of the rollers, being on different radii, have theoretically different rotation speeds. Since this is not possible, compensation is made by sliding which can cause slight wear during use. To limit this effect, the transmitting discs are greased during assembly (conductive grease). The discs being enclosed by the fixed elements 200,300, the grease will remain confined.

[0043] The rollers could be replaced by balls. This has a negative impact on the contacts which become point contacts instead of linear contacts. The arrangement of the tracks to switch to two point contacts would lead to a constraint in the positioning of the crown-shaped plates facing each other, one fixed and the other rotating, arranged on either side of the transmitter disk. However, by construction, the fixed crown-shaped plates 210, 310 are centered on the fixed elements 200, 300 carried by the casing 40 and the rotating crown-shaped plates 110, 120 are centered on the rotating element 100 carried by the rotor shaft 20. Installing an adjustment device does not seem realistic. The rollers give the fixed crown-shaped plates a degree of freedom of eccentricity with the rotating crown-shaped plates.

[0044] [Fig.3] is a sectional view of the entire device 10 passing through the first fixed connection and the section BB in the plane of the crown-shaped conductive plate 310.

[0045] The crown-shaped plate 310, carried by the second fixed element 300, has a tab 311 on its outer periphery. This tab occupies a zone of adapted shape 204 in the periphery of the tubular part 201 of the first fixed element. This tab 311, moreover, ensures that the crown-shaped plate 310 does not rotate.

[0046] On this tab 311 is attached, for example by welding, a conductor 312 passing through a first guide 205 carried by the fixed element 200, then a second guide 42 carried by the casing 40 and held by a plate 43 and a screw 44.

[0047] [Fig-4] is a sectional view of the entire device 10 passing through the second fixed connection and the DC cut in the plane of the crown-shaped conductive plate 210.

[0048] The crown-shaped plate 210, carried by the first fixed element 200, has a tongue 211 on its outer periphery. This tongue 211 occupies a zone of adapted shape 206 in the periphery of the tubular part 201, and also ensures that the crown-shaped plate 210 does not rotate.

[0049] On this tab 211 is attached, for example by welding, a conductor 212 passing through a first guide 207 carried by the fixed element 200 then a second guide 42 carried by the casing 40 and held by the plate 43 and the screw 44.

[0050] [Fig.5] is a front view of the device 10 on the fixing side on the casing showing the relative positions of the conductors 212, 312 in the guides 205, 207 housed in the adapted shapes 204, 206 in the tubular part 201 of the first fixed element.

[0051] [Fig.6] is a sectional view of the entire device 10 passing through the first rotary connection and the section DD in the plane of the crown-shaped conductive plate 120.

[0052] The crown-shaped plate 120, carried by the discoid part 102 of the rotary element 100, has, on its inner periphery, a tongue 121. This tongue occupies a suitable groove 101c in the cylindrical part 101. This tongue 121, moreover, ensures the rotation of the crown-shaped plate 120.

[0053] On this tab 121 is attached, for example by welding, a conductor 122 passing through the cylindrical part 101 in the drilling 101b, and exiting the device 10.

[0054] [Fig.7]is a sectional view of the entire device 10 passing through the second rotary connection and the section EE in the plane of the crown-shaped conductive plate 110.

[0055] The crown-shaped plate 110, carried by the discoid part 102 of the rotating element 100, has, on its inner periphery, a tongue 111. This tongue occupies a suitable shape in the cylindrical part 101 and also ensures the rotation of the crown-shaped plate 110.

[0056] On this tab 111 is attached, for example by welding, a conductor 112 passing through the cylindrical part 101 in the adapted shape 101, and exits the device 10.

[0057] [Fig-8] is a front view of the device 10 on the radial face 202 side, opposite the face fixing on the casing and showing the exit of two rotary conductors 122 and 112 in the drilling 101b and the adapted shape lOld. This view also shows the tab 111.

Claims

Claims

1. Device for supplying current (10) to the rotor of an electrical machine consisting of: • a first fixed element (200), made of insulating material, composed of a radial face (202), a tubular part (201) carrying ears (203) for fixing to a casing (40) using screws (45) and centered on a shoulder (41) of the casing (40) by an internal diameter (201a); • a second fixed element (300), made of insulating material, centered in the first fixed element (200); • a rotary element (100), made of insulating material, carried by a rotor shaft (20); • two current transmitting discs (400) interposed between the fixed elements and the rotary element;characterized in that in the tubular part (201) of the fixed element (200) is arranged the rotary element (100) between the radial face (202) and the second fixed element (300) and all of the components are brought into contact and under pressure by a corrugated washer (320) pushing on the second fixed element (300) while bearing on the first fixed element (200).;

2. Current supply device (10) for the rotor of an electrical machine according to claim 1 characterized in that on the radial face (202), internal side of the fixed element (200) is attached, for example by gluing, a crown-shaped plate (210): • made of conductive material, preferably copper or copper alloy; • provided with a tab (211), housed in a suitable shape (206) in the cylindrical part (201), making the crown-shaped plate (210) fixed, and on the tab (211) is fixed a conductor (212) which, first, runs along the cylindrical part (201) in a guide (207) housed in the suitable shape (206) then passes through a guide (42) carried by the casing (40).

3. Device for supplying current (10) to the rotor of an electric machine according to claim 1 characterized in that on the second

4.

5. fixed element (300), side oriented towards the radial face (202), is attached, for example by gluing, a crown-shaped plate (310): • made of conductive material, preferably copper or copper alloy; • provided with a tab (311), housed in a suitable shape (204) in the cylindrical part (201), making the crown-shaped plate (310) fixed, and on the tab (311) is fixed a conductor (312) which, first, runs along the cylindrical part (201) in a guide (205) housed in the suitable shape (206) then passes through a guide (42) carried by the casing (40). Device (10) for supplying current to the rotor of an electrical machine according to claim 1, characterized in that two crown-shaped plates (110), (120) are attached to the rotating element (100), for example by gluing, on either side of its discoid part (102): • made of conductive material, preferably copper or copper alloy; • each provided with a tab (111), (121) housed in the adapted shapes (101d), (110c) of the cylindrical part (101), making the crown-shaped plates (110), (120) rotatable and on these tabs are fixed the conductors (112), (212) passing the first in the adapted shape (101d), and the second in a hole (101b) in the rotating element (100), in order to be able to be connected to the rotor coils. Current supply device (10) for the rotor of an electrical machine according to claims 1 to 4, characterized in that between the crown-shaped plates (110), (210) on the one hand and (120), (310) on the other hand are interposed the transmitter discs (400) composed of an annular disc (401) made of insulating or metallic material (preferable for mechanical strength) and which has, on a circle, a large quantity of rectangular openings in which are inserted rollers (402), all identical cylindrical, made of conductive material, copper or copper alloy, of diameter greater than the thickness of the annular disc (401).

6. Current supply device (10) for the rotor of an electric machine according to claims 1 and 5, characterized in that the assembly of components, to thus best ensure the transmission of the electric current between the facing crown-shaped plates 110, 210 and 120, 310, is pressurized by a corrugated washer (320) located in a diameter (302b) of the second fixed element (300) on which a washer (321) held by a stop ring (322) located in a groove of the first fixed element (200) rests.

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