Electric machine with a ring of fluid for cooling winding heads

Abstract

The invention relates to an electric machine comprising a stack of stator laminations having wire winding heads projecting on the sides, and comprising, on one side, a cooling fluid circulation ring (8) surrounding the winding heads, forming, with a housing of the machine, an annular chamber (28) having a rear circular seal (24) and a front circular seal (26), which delivers the fluid to the winding heads, the ring (8) being formed by at least two contiguous angular sectors (14), each sector (14) comprising a specific portion of each circular seal (24, 26), and end seals (30) on contiguous faces (16) between the angular sectors (14).

Description

[0001] DESCRIPTION

[0002] TITLE: ELECTRIC MACHINE WITH COOLING FLUID RING FOR THE WINDING HEADS

[0003] 001. The present invention claims priority from French application No. 2407515 filed on 10.07.2024, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004] 002. The present invention relates to an electrical machine comprising rings for circulating a cooling fluid around the stator winding heads, as well as an electric or hybrid motor vehicle equipped with this type of machine.

[0005] 003. A known type of electrical machine, presented in particular by document EP-A1-4270733, comprises a stator formed by a stack of sheets tightly packed in a casing, including windings of copper wire inserted in grooves having winding heads protruding from the sides of the stack, and around these grooves axial bores receiving circulation tubes for a cooling fluid, in particular an oil.

[0006] 004. A fluid circulation pump supplies a central bore in the rotor shaft comprising injectors directed towards the inside of the winding heads, and supplies tubes comprising fluid injectors directed towards gutters arranged around the winding heads, which then spray these heads through a succession of bores distributed along their length.

[0007] 005. Cooling of the winding heads is achieved by a radially internal flow with the fluid coming from the shaft and radially external flow with that coming from the gutters.

[0008] 006. Generally speaking, the traction motor for an electric or hybrid vehicle requires high power, good efficiency, and a compact design to minimize its size and weight, and thus keep costs down. Oil circulation close to the copper wires, releasing heat energy through the Joule effect, helps to improve these parameters.

[0009] 007. Another type of electrical machine, presented in particular by document W0-A1-2022237214, has on each side of the stator a fluid circulation ring surrounding the winding heads, forming a closed circular chamber supplied by the cooling fluid, having radially inwardly directed holes towards these heads to cool them.

[0010] 008. Each ring is formed by an outer contour receiving the fluid inlet, fitted to an inner contour to form the annular chamber, each contour being formed of three assembled angular sectors completing the full turn.

[0011] 009. Furthermore, it is known to have around the winding heads a fluid circulation ring comprising on its outer contour two continuous circular seals axially offset, one bearing on an inner surface of the casing and the other on the end of the stator sheet metal stack, which delimit between them the closed annular chamber receiving the fluid to distribute it around the heads.

[0012] 010. However, in the case of a ring formed from several assembled angular sectors, surrounded by continuous circular seals, the ring assembly requires spacing between the sectors, leading to problems with seal stretching and a risk of damage. Furthermore, the sealing of the annular chamber at the contact surfaces between the sectors is not guaranteed, which can result in fluid losses that are then unavailable for cooling the windings.

[0013] 011. The present invention is specifically designed to avoid these problems of the prior art.

[0014] 012. It proposes for this purpose an electrical machine comprising a stack of stator laminations having winding heads protruding on the sides, and comprising on one side a cooling fluid circulation ring surrounding the winding heads, forming with a machine housing an annular chamber having a rear circular sealing gasket and a front circular sealing gasket, which delivers the fluid to the winding heads, the ring being formed by at least two contiguous angular sectors, this machine being notable in that each sector has its own part of each circular sealing gasket, separate from the other sectors, and end sealing gaskets on contiguous faces between the angular sectors. 013.One advantage of this electric machine is that by equipping each sector with its own section of circular seals and end seals, the sectors are individually fitted around their perimeters, allowing them to be handled and separated independently during installation, thus avoiding any risk of stretching or damaging the circular seals. Furthermore, after assembly, complete sealing of the annular chamber is ensured, including at the joints between the sectors.

[0015] 015. The electrical machine according to the invention may further comprise one or more of the following characteristics, which may be combined with each other.

[0016] 016. Advantageously, each sector end has its own end seal.

[0017] 017. In this case, advantageously for each sector the rear joint part, the front joint part and the two end joints form a continuous contour of the chamber part of that sector.

[0018] 018. Advantageously, all the sealing joints in each sector are formed by the same overmolding of an elastic material.

[0019] 019. Advantageously, each end joint is arranged in a hollow of its adjoining face allowing direct support between the adjoining faces of two facing sectors.

[0020] 020. Advantageously, the rear sealing gasket rests on the front transverse face of the stator laminations and the front sealing gasket rests on a transverse face of the machine housing.

[0021] 021. Advantageously, on each sector the two parts of circular joints are connected to each other by several links of the same material inside the annular chamber.

[0022] 022. Advantageously, each sector comprises a ring arranged in a transverse plane which receives an angular orientation pin linked to the stator.

[0023] 023. The invention further relates to an electric or hybrid motor vehicle, notable in that it comprises an electric machine used for its traction, which is according to any one of the preceding claims. 024. The invention will be better understood and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which: 025. [Fig. 1] is a view of the end of the stator of an electric machine according to the invention;

[0024] 026. [Fig. 2] is an axial cross-sectional view of a part of this machine showing the fluid circulation ring;

[0025] 027. [Fig. 3] is an overview of this ring formed by two sectors; and

[0026] 028. [Fig. 4] is a detailed view of the assembly of the two rings together.

[0027] 029. Figures 1, 2, 3 and 4 show the side of a stator 2 of an electrical machine rotated axially towards a forward direction AV directed outwards, formed by a stack of laminations 38, including the heads of the windings 4 exiting this stack which are inscribed in a circular contour having at the front end an external boss 32.

[0028] 030. Three superimposed conductive rings 6 arranged in front of the winding heads 4 receive the current from each of the phases of these windings of the three-phase machine to connect them to a terminal block 10 comprising three terminals 12 for electrical connection to the outside.

[0029] 031. A cooling fluid circulation ring 8 comprises two equal sectors 14 made by a plastic molding, which are connected to each other by adjoining flat faces 16 arranged along an axial plane.

[0030] 032. Each ring sector 14 has at one end a radially turned inwards lug 40, disposed in a transverse plane which is perpendicular to the axis of the machine, comprising a bore which receives in a fitted manner a pin 42 fixed on the outermost conducting ring 6 to form an angular positioning stop of the ring 8 around the axis.

[0031] 033. The rear portion of the sectors 14 is separated from the housing 22 to form an annular chamber 28 between them, which is delimited at the rear by the transverse face 34 of the stator laminations 38, which include axial holes 20 supplying fluid to this chamber. The radially inner face of the fluid circulation ring 8 has, at the level of the annular chamber 28, holes 36 facing the winding heads 4 in order to distribute the fluid onto them.

[0032] 034. Each sector 14 includes a proper part of two circular sealing gaskets, covering the length of the sector, comprising a rear gasket 24 fixed on the rear end of these sectors, bearing on the front transverse face 34 of the stator sheets 38, and a front gasket 26 fixed on the rear face of an annular boss 48 bearing on a circular transverse face of the housing 22.

[0033] 035. At each end of the sectors 14, the two rear circular seals 24 and front circular seals 26 are connected by an end seal 30 covering the adjoining faces 16 of these sectors at the level of the annular chamber 28, so as to form on each sector a continuous contour comprising the circular seals and the two end seals. Each end seal 30 is disposed in a recess in its adjoining face 16, allowing direct contact between the opposing adjoining faces.

[0034] 036. The two parts of the two circular joints 24, 26 are connected to each other by several links of the same material 50 arranged in an axial plane inside the annular chamber 28, and distributed over the contour of the ring 8.

[0035] 037. Advantageously on each sector 14 the set of joints 24, 26, 30 is formed by the same overmolding of an elastic material which ensures adhesion to the sector and continuity of the joint.

[0036] 038. Each end of the sectors 14 has one or two circumferentially oriented tabs 44 that protrude from the adjoining face 16 to fit into a recess 46 formed on the opposite sector, in order to ensure alignment of these ends with each other and with the circular sealing gaskets. 039. For each sector 14, continuous sealing is achieved around the perimeter of the annular chamber 28, comprising the two circular gasket sections 24, 26, and the end gaskets 30 connected without discontinuity to these circular gaskets, which constitute a watertight perimeter of the annular chamber section of the sector.

[0037] 040. The installation of the complete fluid circulation ring 8 is facilitated by its division into two sectors 14, each independently comprising the complete sealing contour of its annular chamber portion 28, which is fixed to it. The independent approach of the sectors 14 to the stator during the assembly of the electrical machine is facilitated, without risk of damage to the seals, by separating them sufficiently to pass over the radially external boss 32 of the winding heads 4, and then bringing them together and fitting them into the bore of the machine housing 22.

Claims

DEMANDS 1. An electric machine comprising a stack of stator laminations (38) having winding heads (4) protruding on the sides, and comprising on one side a cooling fluid circulation ring (8) surrounding the winding heads (4), forming with a machine housing (22) an annular chamber (28) having a rear circular sealing gasket (24) and a front circular sealing gasket (26), which delivers the fluid onto the winding heads (4), the ring (8) being formed by at least two contiguous angular sectors (14), characterized in that each sector (14) has its own part of each circular sealing gasket (24, 26), separated from the other sectors (14), and end sealing gaskets (30) on contiguous faces between the angular sectors (14).

2. Electric machine according to claim 1, characterized in that each sector end (14) has its end seal (30).

3. Electric machine according to claim 2, characterized in that for each sector (14) the rear joint part (24), the front joint part (26) and the two end joints (30) form a continuous contour of the chamber part (28) of this sector (14).

4. Electric machine according to any one of the preceding claims, characterized in that all the sealing joints (24, 26, 30) of each sector (14) are formed by the same overmolding of an elastic material.

5. Electric machine according to any one of the preceding claims, characterized in that each end joint (30) is disposed in a hollow of its adjoining face (16) allowing direct support between the adjoining faces (16) of two sectors (14) opposite each other.

6. Electric machine according to any one of the preceding claims, characterized in that the rear sealing gasket (24) is supported on the front transverse face (34) of the stator laminations (38) and the front sealing gasket (26) is supported on a transverse face of the machine housing (22).

7. An electrical machine according to any one of the preceding claims, characterized in that on each sector (14) the two parts of circular joints (24, 26) are connected to each other by several links of the same material (50) inside the annular chamber (28).

8. An electrical machine according to any one of the preceding claims, characterized in that each sector (14) comprises a ring (40) disposed in a transverse plane which receives an angularly oriented pin (42) connected to the stator.

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

Images