Endshields for rotating electrical machines

Abstract

The invention proposes an end shield for an X-axis rotating electrical machine, comprising a side wall and a transverse wall, the side wall comprising at least three support surfaces, the support surfaces being axial and regularly arranged circumferentially around the axis X, each axial support surface being intended for surface contact with a plane of the reducer.

Description

[Technical Field]

[0001] The present invention particularly relates to end shields for rotating electrical machines.

[0002] The present invention is particularly advantageously, but not exclusively, applicable to high power reversible electric machines that can operate in alternator and motor modes and that are coupled to reduction elements. [Background technology]

[0003] In a manner known per se, a rotating electric machine has a stator and a rotor fixed to a shaft, the stator being mounted in a casing adapted to rotatably support the shaft on end shields by means of rolling bearings.

[0004] The rotor has a body formed by a stack of laminations held in a pack by a suitable fastening system. The rotor has magnetic poles formed, for example, by permanent magnets housed in cavities in the magnetic material of the rotor. Alternatively, in what is known as a "salient pole" structure, the magnetic poles are formed by coils wound around the arms of the rotor.

[0005] The stator has a body formed by a stack of thin laminations forming a ring, the inner surface of which is provided with slots that open inward to accommodate the windings. The windings are made, for example, from continuous wire covered with enamel or from conductive elements in the form of hairpins connected to each other by welding. The windings have star-connected or delta-connected phase windings, the outputs of which are connected to the electronic control module.

[0006] In some types of automotive drivetrains, which transmit mechanical power from an internal combustion engine to the vehicle wheels, a high-power reversible rotating electric machine may be coupled via a connecting piece to a reduction element, which may take the form of a vehicle transmission or a speed reducer attached to the vehicle's axle system and coupled to the rotating electric machine.

[0007] The rotating electric machine can operate in alternator mode, in particular to supply energy to the battery and to the vehicle's on-board network, and can operate in motor mode to start the internal combustion engine and / or to power the vehicle alone or in combination with the internal combustion engine.

[0008] To provide a mechanical connection between the electric machine and a connecting piece connected to the reduction element, a spline for coupling the shaft of the electric machine interacts with a complementary spline on the connecting piece. However, misalignment between the axis of the shaft of the machine and the axis of the connecting piece when connecting the machine and the reduction gear can damage the machine when it is rotated, in particular deteriorating the rolling bearings. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to make it possible to avoid the drawbacks of the prior art. [Means for solving the problem]

[0010] To this end, one subject of the invention is therefore an end shield for a rotating electrical machine of axis X, comprising a side wall and a transverse wall, the side wall comprising at least three abutment surfaces, the abutment surfaces being axial and regularly arranged circumferentially around the axis X, each axial abutment surface intended to be in surface contact with a plane of a reducer.

[0011] The invention therefore makes it possible to align the axes of the machine and the reduction element.

[0012] At least one axial abutment surface is advantageously planar.

[0013] The side wall is advantageously provided with three lugs extending radially therefrom, the three lugs being regularly arranged around the axis X, each lug having a radial abutment surface perpendicular to the axis X, each radial abutment surface (170) intended for surface contact with another plane of the reducer.

[0014] Each lug is advantageously provided with a circular through opening along X.

[0015] Each through opening is radially aligned with an axial face.

[0016] At least one lug also includes an oblong opening along X therethrough.

[0017] Another subject of the present invention is an automobile assembly comprising a rotating electrical machine having a shaft, a rotor attached to the shaft, in particular a stator surrounding the rotor, a front end shield according to any one of the preceding claims, having a rolling bearing for guiding the rotation of the shaft, the front end shield having an end protruding axially relative to the rolling bearing and splines provided on the end of the shaft, and a reduction element having a connecting piece having complementary splines that interact with the splines on the end of the shaft to provide a mechanical connection between the shaft and the connecting piece of the reduction gear, the reduction element having a flat surface that is in surface contact with the abutment surface of the end shield.

[0018] Another subject of the invention is a method for manufacturing an end shield, in which at least one abutment surface is obtained by machining.

[0019] All abutment surfaces can advantageously be obtained with a single pass of the machining tool.

[0020] In the case of end shields provided with through openings, at least one opening can be obtained by a simple drilling operation.

[0021] The invention therefore makes it possible to obtain a position determination system for aligning the machine axis and the reducer axis in a simple manner.

[0022] The invention will be better understood on reading the following detailed description of non-limiting exemplary embodiments of the invention and on examining the accompanying drawings, in which: [Brief explanation of the drawings]

[0023] [Figure 1] 1 shows a rotating electrical machine according to the invention; [Figure 2] FIG. 2 is a diagram showing a machine and a reducer together with a contact surface of the reducer. [Figure 3] FIG. 2 is a diagram showing a machine and a reducer together with a contact surface of the machine. [Figure 4a] FIG. 2 is a view showing the radial and axial abutment surfaces of the end shield. [Figure 4b] FIG. 10 is a cross-sectional view of the radial and axial abutment surfaces of the wall of the end shield. [Figure 5a] 10A and 10B are diagrams illustrating the abutment of the reducer with the end shield. [Figure 5b] FIG. 10 shows a pin passing through an oblong opening in a bearing. DETAILED DESCRIPTION OF THE INVENTION

[0024] Equivalent, similar, or analogous elements retain the same reference numerals from one figure to another. Additionally, the exemplary embodiments described below are in no way limited.

[0025] Throughout the remainder of the description, the front-to-rear orientation is considered to be from left to right in Figure 1. Thus, "front" elements are understood to mean elements located on the side of the front rolling bearing 9a, and "rear" elements are understood to mean elements located on the opposite side, i.e., on the side of the electronic control module 34.

[0026] Throughout the remainder of the description, axial refers to the direction of axis X, and thus axial planes refer to planes extending along and around axis X. Radial refers to directions extending from axis X in planes perpendicular to axis X, and thus radial planes refer to planes perpendicular to axis X. Circumferential refers to directions extending around axis X in planes perpendicular to axis X.

[0027] 1 shows a rotating electric machine 100 having a multi-phase stator 1 surrounding a rotor 2 mounted on a shaft 3 of axis X corresponding to the axis of the electric machine 100. The stator 1 surrounds the rotor 2 with a gap between the inner peripheral surface of the stator 1 and the outer peripheral surface of the rotor 2. The stator 1 is mounted in a casing 4 having a front end shield 5 and a rear end shield 6. The front end shield 5 and the rear end shield 6 each have housings 7, 8 for receiving corresponding rolling bearings 9a, 9b that guide the rotation of the shaft 3 through a lateral wall 20 of the front end shield 5.

[0028] The stator 1 is attached inside the front end shield 5 between the stator 1 and a side wall 15 of the front end shield 5 .

[0029] This electric machine 100 is intended to be coupled to a reduction element 22 via a connecting piece 23 which can be seen in FIG.

[0030] The reduction element 22 may take the form of a transmission for the automobile or a speed reducer attached to the axle system of the vehicle and coupled to the rotating electrical machine 100 .

[0031] The electric machine 100 can operate in alternator mode, in particular to supply energy to the battery and to the vehicle's on-board network, and in motor mode to start the vehicle's internal combustion engine and, where appropriate, to power the vehicle alone or in combination with the internal combustion engine. The power output of the machine can be, for example, between 15 kW and 50 kW.

[0032] More specifically, rotor 2 has a body 24 in the form of a pack of laminations. Permanent magnets 25 are mounted in cavities 26 within body 24. Magnets 25 may be rare earth magnets or ferrite magnets, depending on the application and the desired output of the machine.

[0033] The rotor 2 also has two bearings 28, 29 that are pressed against the axial end faces of the rotor 2. These bearings 28, 29 are also used to hold the magnets in the axial direction and balance the rotor 2.

[0034] Furthermore, the stator 1 has a body 31 formed by a pack of laminations as well as windings 32. The body 31 is formed by a stack of laminations held in the form of a pack by a suitable fastening system such as rivets.

[0035] The body of the stator 1 is provided with teeth separating slots for mounting the windings 32. The windings 32 have a set of phase windings that pass through the slots and form bundles that protrude on both sides of the body of the stator 1. The windings 32 are obtained in this case from conductive elements in the form of hairpins connected to each other, for example by welding. The windings 32 have dual three-phase windings of star and / or delta connection. The phase outputs are intended to be connected to an electronic control module 34.

[0036] The electronic control module 34 has a heat sink, to which in particular the power modules 36 are fastened, for example by screw fastening. These power modules 36 incorporate switches, for example in the form of MOS transistors, in a manner known per se, which make it possible to control the phases of the rotating electrical machine 100 in motor mode or alternator mode. The switching of these transistors is controlled by a control unit. The electronic control module 34 is mounted via a heat sink 35 against the rear face of the lateral wall of the rear end shield 6.

[0037] As can be seen in FIG. 3, the front end 47 of the shaft 3, which projects axially relative to the rolling bearing, is provided with splines 48, in this case oriented axially relative to the axis X. The splines 48 at the end of the shaft 3 interact with complementary splines 49 on the connecting piece 23, which is shown in FIG. 2. The splines 49 are formed annularly and axially oriented on the inner circumferential surface of the connecting piece 23. In this way, the teeth of the splines 48, 49 of one element intersect with the spaces separating the teeth of the splines 48, 49 of the other element, and vice versa. This makes it possible to provide a mechanical rotational connection between the shaft 3 and the connecting piece 23. The connecting piece 23 is also rotationally connected to the reduction element 22, in particular by a spline connection.

[0038] As shown in Figure 3, the outer circumferential surface of the side wall of the front end shield 5 is provided with three projections 16 regularly arranged in the circumferential direction around the axis X. The three projections 16 therefore extend from the outer circumferential surface of the side wall in such a way that three planes offset by 120° around the axis X, which contain the machine axis and intersect the side wall of the end shield, are each intersected by one projection 16. The advantage of having three projections rather than a ring going around the periphery of the end shield is that at least the side wall 15 of the end shield is covered, optimizing its cooling, and in particular the air passages in the wall of the end shield are not covered.

[0039] Each projection 16 has an axial abutment surface 160, i.e., a surface that extends axially around the axis X and is shown in FIG. 4a. The axial abutment surface 160 is advantageously planar. The circumferential extent of the surface is limited to a few millimeters, typically 8 millimeters, which is very small compared to the circumference of the end shield, so that the surface can be considered as a plane. The axial surfaces of the end shield are advantageously aligned axially, i.e., a plane perpendicular to the axis X that intersects one of the axial surfaces intersects the other two axial surfaces.

[0040] The reduction element also has three planar axial faces 51 regularly spaced circumferentially around the axis of the connecting piece of the reduction element. The three axial faces 51 are also axially aligned and equidistant radially from the axis X' of the connecting piece, so that when the end shield is assembled to the reduction element, each axial abutment face 160 of the end shield faces abuttingly faces 51 of the reduction element. These abutment faces 160, 51 allow the axis X' of the reduction element to be aligned with the axis X of the machine by using the centering stop formed by face 160 relative to face 51 to limit the radial clearance for alignment. This eliminates the clearance caused by attaching the reducer to the end shield using screws, which would lead to inaccurate alignment as the only means of aligning the axes.

[0041] The end shield also comprises three lugs 17 extending radially from the side wall. The three lugs 17 are regularly arranged circumferentially about the axis X. Thus, the three lugs 17 extend from the outer circumferential surface of the side wall 15 in such a way that three planes offset by 120° about the axis X, which contain the machine axis and intersect the end shield side wall, intersect one lug each.

[0042] Each lug 17 has a radial abutment surface 170 shown in Figure 4a, perpendicular to the axis X. The radial abutment surfaces are advantageously planar. These radial abutment surfaces are advantageously axially aligned, i.e. the plane containing one of the radial abutment surfaces also contains the other radial abutment surfaces. The reduction element also comprises three planar radial surfaces 52 regularly arranged around the axis X of the machine, radially equidistant from the axis and axially aligned.

[0043] As a result, when the reduction element is assembled to a machine, each radial abutment surface 170 abuts flush against the radial abutment surface 52 of the opposing reduction element. This abutment allows for axial alignment of the reduction element with the machine. The axial and radial abutments are shown in FIG. 5.

[0044] Each lug 17 advantageously has a circular through-opening 171, shown in Figure 4a, through which a nut is passed for assembling the reduction element to the machine. The through-opening 171 is advantageously located in the centre of the radial abutment surface 170, which is advantageously circular.

[0045] In an advantageous embodiment, the axial and radial abutment surfaces are radially aligned, i.e., the plane containing the machine axis X and intersecting the projection 16 also intersects the through opening 171. The proximity of the abutment surfaces facilitates machining of the abutment surfaces, as will be explained below. The proximity of the surfaces also makes it possible to minimize tolerance runout between the axial and radial alignment of the X and X' axes. The axial and radial abutment surfaces 51, 52 of the reduction element are also radially aligned along the three arms of the reduction element shown in FIG. 2.

[0046] The axial and radial abutment surfaces 160 and 170 of the end shield are obtained by milling. The milling cutter used for machining simultaneously machines the two radially aligned abutment surfaces 160 and 170 in one pass of the machining tool, typically over a 30° sector. The tool then moves radially away from the end shield and then moves circumferentially around the machine axis to machine the next sector of the end shield.

[0047] The advantage of simultaneously machining two aligned radial and vertical abutment surfaces is that good perpendicularity between these two reference surfaces is ensured since the workpiece does not move relative to the machining tool and therefore the reference is not lost.

[0048] After passing through the machining tool, the cross section of the end shield in a plane containing axis X and intersecting lug 16 and opening 171 is as shown in Figure 4b. The radial abutment surface is in the same plane as radial face 180 of lug 16. Lug 16 therefore has a raised portion 18, since the milling process cuts lug and lug at the same axial level. The excess thickness of the lug, over which abutment surface 170 extends, makes it possible to avoid interference between the machine and the reducer by a distance D shown in Figure 5a when face 52 abuts on the reducer side.

[0049] The lug 17 also advantageously includes an oblong opening 19 for receiving a mating pin 19a shown in Figure 5b to ensure angular positioning of the assembly relative to the motor.

[0050] The circular opening 171 and the oblong opening 19 are advantageously obtained by simple drilling operations without precise resizing, because very precise alignment is already achieved by using the abutment surfaces 160, 170. These assembly openings and angular alignment openings are very easily produced by simple drilling operations.

Claims

1. An end shield (5) for a rotating electrical machine of axis X, comprising a side wall (15) and a transverse wall (20), The side wall (15) has at least three abutment surfaces (160), said abutment surfaces (160) being axial and regularly arranged circumferentially around said axis X; An end shield (5), each axial abutment surface (160) intended for surface contact with a flat surface of the reducer.

2. The end shield of claim 1 , wherein at least one axial abutment surface (160) is planar.

3. The side wall (15) is provided with three lugs (17) extending radially from the side wall (15); These three lugs (17) are regularly arranged around the axis X, Each lug (17) has a radial abutment surface (170) perpendicular to said axis X, 3. An end shield according to claim 1 or 2, wherein each radial abutment surface (170) is intended for surface contact with another flat surface of the reducer.

4. 4. An end shield according to claim 3, wherein each lug is provided with a circular through opening (171) along X.

5. The end shield of claim 4, wherein each through opening (171) is radially aligned with the axial surface (160).

6. 6. An end shield according to any one of claims 3 to 5, wherein at least one lug (17) also comprises an oblong through-opening (19) along X.

7. 1. A vehicle assembly comprising: a rotating electrical machine (100) comprising a shaft (3), a rotor (2) attached to said shaft, and in particular a stator (1) surrounding said rotor; 7. A front end shield (5) according to any one of claims 1 to 6, comprising rolling bearings (9a, 9b) for guiding the rotation of the shaft, a front end shield (5) in which the shaft (3) has an end that protrudes axially relative to the rolling bearing, and the end of the shaft is provided with a spline (48); a reduction element (22) provided with a connecting piece (23) of the reducer having complementary splines (49) that interact with the splines (48) on the end of the shaft to provide a mechanical connection between the shaft and the connecting piece (23) of the reducer; and The deceleration element is provided with flat surfaces (51, 52) that come into surface contact with the abutment surfaces (160, 170) of the end shields.

8. A method for manufacturing an end shield according to any one of claims 1 to 6, wherein at least one abutment surface is obtained by machining.

9. 9. The method of claim 8, wherein all of the abutment surfaces are obtained in a single pass of the machining tool.

10. 10. A method according to claim 8 or 9, wherein in the case of end shields provided with through openings, at least one opening is obtained by a simple drilling operation.

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