ELECTRIC MACHINE WITH STATOR COMPRISING AXIAL DRILLINGS FOR COOLING FLUID

Abstract

Electrical machine comprising a stator (2) having an axis of rotation, comprising a stack of sheets (38) having electrical wire winding heads (4) projecting axially, and around these windings (4) axial bores for circulating a cooling fluid, this machine comprising around the winding heads (4) a fluid circulation ring (14) forming an annular chamber receiving the fluid from the axial bores to distribute it towards the heads of the windings (4), which comprises at least one stop (48) achieving its angular positioning around the axis. Figure 1

Description

Title of the invention: ELECTRIC MACHINE WITH STATOR COMPRISING AXIAL DRILLINGS FOR COOLING FLUID

[0001] The present invention relates to an electric machine with a stator comprising axial holes for circulating a cooling fluid, as well as a method of assembling this machine and an electric or hybrid motor vehicle equipped with this type of machine.

[0002] A known type of electrical machine, presented in particular by document EP-Al-4270733, comprises a stator formed by a stack of sheets clamped in a casing, comprising around the copper wire windings, near the outside diameter of the sheets, axial holes for the circulation of a cooling fluid, in particular an oil.

[0003] A fluid circulation pump supplies a central bore of the rotor shaft, as well as tubes inserted into the bores of the stator, comprising several holes forming fluid injectors. In particular, an injector formed on each side of the tube makes it possible to spray fluid into a gutter arranged along the circumference of the stator around the heads of the windings, which then waters these heads through a succession of bores distributed along the length of the gutter.

[0004] Thus, by the arrival of the fluid coming from the shaft on the radially inner contour of the winding heads, and coming from the gutters on their radially outer contour, a watering of the ends of the wire windings is obtained which cools them.

[0005] In particular for a traction machine of an electric or hybrid vehicle, we are looking for both significant power and good efficiency with a compact machine to limit its size, and a minimum of materials to reduce mass and costs. Circulating oil as close as possible to the copper wires releasing heat energy by the Joule effect makes it possible to improve these parameters.

[0006] However, fluid distribution chutes acting solely by gravity do not allow the distribution of the fluid flow rate to be optimized over the complete contour of the ends of the windings, which poses problems of optimization of heat exchanges on these parts producing calories, in particular depending on the angular position of each winding.

[0007] The present invention aims in particular to avoid these problems of the prior art.

[0008] To this end, it proposes an electrical machine comprising a stator having an axis of rotation, comprising a stack of sheets having axially projecting electrical wire winding heads, and around these windings axial drillings of circulation of a cooling fluid, this machine comprising around the winding heads a fluid circulation ring forming an annular chamber receiving the fluid from the axial bores to distribute it towards the winding heads, this machine being remarkable in that the sealing ring comprises at least one stop achieving its angular positioning around the axis.

[0009] An advantage of this electric machine is that by providing at least one angular positioning stop on the sealing ring, for example an element fitting into another fixed element, an angular position of this ring is automatically obtained during assembly of the machine, precisely adjusting the angular distribution of the injectors formed on the ring.

[0010] This ensures, by simply adding shapes which can be produced economically in molded parts, ease of series assembly of the machines giving a precise distribution of the flow according to the angular sectors of the windings and their particular thermal exchange requirements, so as to obtain maximum regularity of temperatures which optimizes the power and efficiency of the machine.

[0011] The electrical machine according to the invention may further comprise one or more of the following characteristics, which may be combined with each other.

[0012] Advantageously, the angular positioning stop comprises a pin arranged axially entering a bore.

[0013] Advantageously, the angular positioning stop comprises an element fixed to a current-conducting ring arranged at the end of the windings.

[0014] In addition, the fluid circulation ring may comprise a flat tab comprising the bore which is radially inwardly facing.

[0015] Advantageously, the fluid circulation ring comprises two half-rings which join along a joint plane passing through the axis.

[0016] In this case, advantageously each half-ring comprises an angular positioning stop.

[0017] Advantageously, the fluid circulation ring is formed in one piece with an element of the angular positioning stop by a plastic molding.

[0018] The invention also relates to a method of assembling an electrical machine comprising any one of the preceding characteristics, remarkable in that it comprises a step of axial sliding of the fluid circulation ring which comprises, during this sliding, a fitting of two elements of the angular positioning stop.

[0019] Advantageously, the fluid circulation ring comprising two half-rings, the method further comprises a preliminary step of separating the half-rings, then a step of partial sliding to pass bosses on the external contour of the heads of the windings, then a step of tightening the half-rings, and finally a end of sliding step comprising a fitting of the elements of the angular positioning stop.

[0020] The invention further relates to an electric or hybrid motor vehicle, remarkable in that it comprises an electric machine used for its traction comprising any one of the preceding characteristics.

[0021] The invention will be better understood and other characteristics and advantages will appear more clearly on reading the description below given by way of example, with reference to the appended drawings in which:

[0022] [Fig-1] is a view of the end of an electric machine according to the invention without its casing;

[0023] [Fig.2] is an axial sectional view of the end of the machine passing through the positioning stop;

[0024] [Fig.3] is a top view of the ring positioning stop of this machine; and

[0025] [Fig.4] is a bottom view of this stop, showing the angular positioning pin of the fluid circulation ring without the conductive crowns.

[0026] Figures 1 and 2 show the front axial side AV of a stator 2 of an electrical machine formed by a stack of sheets 38, comprising the heads of the wire windings 4 projecting axially on each side of this stack, having on their outer contour a boss 32 facing radially outwards.

[0027] Three superimposed conductive rings 6, arranged in front of the winding heads 4, receive the current from each of the phases of the three-phase machine via connections 8, to connect them to a terminal block 10 comprising three terminals 12 for electrical connection to the outside.

[0028] A fluid circulation ring 14 produced by molding a plastic material comprises two half-rings connected along a joint plane passing through the axis 16, each having an axial bore 18 near this plane.

[0029] The rear base 24 of the ring 14, resting on the transverse face 34 of the stator laminations 38, is radially spaced from the casing 22 so as to form between them an annular chamber 28 which is closed towards the front by an axial support of the ring 26 on a boss of this casing. A sealing membrane 30 covers the part of the ring 14 forming the chamber 28 in order to ensure the sealing of the contact on the stator laminations 38 and on the casing 22.

[0030] Figures 3 and 4 show each half-ring comprising at one end, opposite an axial bore 18, a radially inwardly facing tab 40, arranged in a transverse plane, comprising a bore which receives in an adjusted manner a pin 42 fixed on the outermost conductive ring 6 to form a stop 48 for angular positioning of this ring around the axis. Each tab 40 extends towards the rear by an axial plane 44 which connects it to the external boss 46 of its bore 18 arranged opposite.

[0031] The method of assembling the fluid circulation ring 14 is as follows. A tool comprising two parts, each having two rods, receives the ring 14 by introducing the two rods of each part into the holes 18 of the same half-ring. The tool then performs a step of radially separating the half-rings in order to obtain a larger interior space allowing their base 24 to pass above the external bosses 32 of the winding heads 4.

[0032] There is then a step of partial sliding towards the rear to pass the base 24 over the bosses 32, then after this passage a step of tightening the two parts of the tool to reform the circular ring 14, then a step of end of sliding comprising a fitting of two elements of the angular positioning stop 48, and a complete positioning of the ring 14. Then the tool rises towards the front to release its rods from the holes 18.

[0033] Thus, with the support of the sealing membrane 30 on the transverse face 34 of the stator sheets 38 and the axial support 26 on the casing 22, the annular chamber 28 is formed, which receives the fluid coming from the stator bores 20 to distribute it via a series of radial bores distributed over the contour, forming injectors 36 facing the winding heads 4.

[0034] The angular distribution of the injectors 36 on the inner face of the ring 14 may be irregular, so as to favor certain zones of the winding heads 4 receiving a higher flow rate of cooling fluid in order to adapt it to the heating that they produce.

[0035] When the ring 14 is lowered for its installation, the holes in the legs 40 each receive a pin 42 which easily fits thanks to a chamfer at the end of this pin. At the end of the descent, each leg 40 is close to the outer conductive ring 6.

[0036] After removing the assembly tool, a ring 14 is obtained, centered in the casing 22 by its rear part, and positioned angularly by the holes in its legs 42, each receiving a pin 42 connected to the casing 22.

[0037] Alternatively, it is possible to use a single pierced tab 40 receiving a single pin 42 which is sufficient to ensure angular positioning of the fluid circulation ring 14. It is also possible to use any other type of angular positioning stop, such as a pin of the ring 14 entering a drilling of a fixed element of the machine, the casing 22 for example, or other forms of stop such as a tenon entering an axial groove.

[0038] The plastic molding of the half-rings of the fluid circulation ring 14 makes it possible to easily and economically obtain in the same operation molding of the legs 40.

Claims

Claims

1. Electrical machine comprising a stator (2) having an axis of rotation, comprising a stack of sheets (38) having electrical wire winding heads (4) projecting axially, and around these windings (4) axial bores (20) for circulating a cooling fluid, this machine comprising around the winding heads (4) a fluid circulation ring (14) forming an annular chamber (28) receiving the fluid from the axial bores (20) to distribute it towards the heads of the windings (4), characterized in that the sealing ring (14) comprises at least one stop (48) achieving its angular positioning around the axis.

2. Electrical machine according to claim 1, characterized in that the angular positioning stop (48) comprises an axially arranged pin (42) entering a bore.

3. Electrical machine according to claim 1 or 2, characterized in that the angular positioning stop (48) comprises an element fixed on a current-conducting ring (6) arranged at the end of the windings (4).

4. Electrical machine according to claims 2 and 3, characterized in that the fluid circulation ring (14) comprises a flat tab (40) comprising the bore which is turned radially inwards.

5. Electrical machine according to any one of the preceding claims, characterized in that the fluid circulation ring (14) comprises two half-rings which join along a joint plane passing through the axis (16).

6. Electrical machine according to claim 5, characterized in that each half-ring comprises an angular positioning stop.

7. Electrical machine according to any one of the preceding claims, characterized in that the fluid circulation ring (14) is formed in one piece with an element of the angular positioning stop (48) by a plastic molding.

8. Method of assembling an electrical machine according to any one of the preceding claims, characterized in that it comprises a step of axial sliding of the fluid circulation ring (14) which comprises during this sliding a fitting of two elements of the angular positioning stop (48).

9. An assembly method according to claim 8, the circulation ring of fluid (14) comprising two half-rings, characterized in that it comprises a preliminary step of separating the half-rings, then a partial sliding step to pass bosses (32) on the external contour of the heads of the windings (4), then a step of tightening the half-rings, and finally a step of end of sliding comprising a fitting of the elements of the angular positioning stop (48).

10. Electric or hybrid motor vehicle, characterized in that it comprises an electric machine used for its traction which is according to any one of claims 1 to 7.

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