FR2978631A1 - Stator for electrical motor used for driving e.g. electric car, has carcass in which grooves extending between teeth and winding are formed, where head of winding is formed out of carcass and includes spaced beams and/or spaced conductors - Google Patents

Abstract

The stator (2) has a carcass in which grooves extending longitudinally between teeth (21) and a winding are formed. A head (5a) of the winding is formed out of the carcass, and includes spaced beams of conductors and/or spaced conductors (51). The spaced beams and/or spaced conductors are staggered. A channel element channels coolant e.g. oil, toward the spaced beams and/or the spaced conductors, and/or from the spaced beams and/or the spaced conductors. A case surrounds the head, and forms watertight cavities to receive the coolant.

Description

The present invention relates to an electric machine element comprising a carcass and a coil. The invention also relates to an electric machine comprising such an element. The invention also relates to a motor vehicle comprising such an electric machine.

In an electric motor of an electric vehicle, the thermal losses in the conductors of the windings by the Joule effect generally represent the major part of the thermal power to be evacuated. Moreover, in low-cost motors without magnets, coils are the elements that are least resistant to temperature (180 ° C maximum). Their cooling is therefore crucial.

The difficulty of cooling a winding comes from two main reasons: - there is a large number of thermal barriers hindering the transmission of heat from the winding to a cooling fluid, and - the thermal conductivity of a winding in the direction transverse to the conductors is bad.

In order for a large amount of heat generated in the conductors to be discharged, a very high temperature difference, hence a high winding temperature, must be achieved at constant temperature of the cooling fluid. This is not desirable.

It is therefore important to improve the cooling of the windings.

An electric motor is commonly cooled by either a gas such as air or a liquid such as water. For example, freon or other phase-change heat transfer fluid is used for the engine of an electric compressor of a refrigerating machine and water is used to cool the motor of an electric water pump.

In the case of gas cooling, the gas is ventilated by a fan driven generally by the axis of the electric motor. This gas exchanges heat with the walls of the motor (the external winding walls, the sheet walls). But, several problems severely limiting the performance of heat exchange exist. In particular, the gas exchange coefficients are low, the wall surfaces that contribute to the heat exchange are limited, and especially it is difficult to pass the gas in the areas that heat up. It can also be added that it is difficult, because of constraints related to the architecture of the engines, to bring a sufficient quantity of fresh gas into the engine and to get it out.

In the case of liquid cooling, a jacket containing a liquid is placed on the periphery (housing) of the electric motor (see FIGS. 1 and 2), generally on the stator plates. In these figures, there is shown, in partial cross-section and in longitudinal section, an electric motor 100 known from the prior art. The motor comprises a stator 104 and a rotor 108. Around the rotor is mounted a liquid-cooled housing 105 comprising a chamber 106 for containing the liquid. In the carcass of the stator, grooves 102 are provided to receive the windings 109 having winding heads 107. In these grooves, around the windings, an insulator, such as a cardboard 103, is provided. This insulator makes it possible in particular to provide protection mechanical conductors. Between the conductors of the coils, a resin is impregnated to stiffen the conductors and to improve the transfer of heat from the core of the coil to its periphery. In such an engine, the heat generated inside the winding must, as represented by the arrow in FIG. 1, first out of the winding, then through the air, then through the insulation 103, then through air, pass through the stator housing, and then into the liquid cooling housing. This path includes various thermal barriers significantly limiting the effectiveness of cooling.

There are documents describing solutions to improve the cooling of an engine with air. They essentially use an optimization of the air circulation inside the engine. Documents RU2280305, RU2239272, RU2101835 and RU2286640 are particularly known. Such solutions impose severe architectural constraints.

The object of the invention is to provide an electric machine element to overcome the disadvantages identified above and to improve the electrical machine elements known from the prior art. In particular, the invention provides an electric machine element having a simple structure, inexpensive and to improve its cooling without creating architectural constraints on the machine.

According to the invention, an electric machine element comprises a carcass and a coil. A winding head includes a plurality of spaced beams of conductors and / or a plurality of spaced apart conductors.

The element may comprise, at the level of the head, spaces between the spaced beams of conductors and / or between the spaced conductors, the gaps being for example between 1 mm and 4 mm, in particular between 2 mm and 3 mm. . The beams may comprise layers of conductors. The spaced beams and / or the spaced conductors may be staggered.

The element may comprise a heat transfer fluid channeling element: to spaced apart conductor bundles and / or to spaced conductors, and / or from spaced conductor bundles and / or spaced conductors. The element may comprise a housing surrounding the head and intended to receive a heat transfer fluid. According to the invention, an electric machine, in particular an electric motor, in particular an electric motor of a motor vehicle, comprises a previously defined element.

The electric machine may comprise a heat-transfer fluid setting element between the spaced beams of conductors and / or between the spaced conductors.

According to the invention, the motor vehicle comprises an electric machine 20 defined above.

The appended drawing shows, by way of example, several embodiments of an electric machine element according to the invention.

Figure 1 is a partial cross-sectional view of an electric motor known from the prior art.

Figure 2 is a longitudinal sectional view of an electric motor known from the prior art. Figure 3 is a longitudinal sectional view of a first embodiment of an electric motor according to the invention. Fig. 4 is a partial perspective view of a first variant of the first embodiment of the electric motor.

Figure 5 is a partial longitudinal sectional view of the first variant of the first embodiment of the electric motor.

Figure 6 is a partial longitudinal sectional view of a second variant of the first embodiment of the electric motor. Figure 7 is a partial longitudinal sectional view, perpendicular to that of Figure 6, of the second variant of the first embodiment of the electric motor.

Figure 8 is a longitudinal sectional view of a second embodiment of an electric motor according to the invention.

Figure 9 is a longitudinal sectional view of a third embodiment of an electric motor according to the invention. Fig. 10 is a cross-sectional view of the third embodiment of the electric motor.

A first embodiment of electric machine is described below with reference to Figures 3 to 7. The electric machine 1 is for example an electric motor, in particular an electric motor of a motor vehicle for driving the motor vehicle. The electric machine comprises a stator 2 and a rotor 3.

The stator comprises a carcass 20 in which longitudinally extending grooves are formed between teeth 21 and coils 4 whose electrical conductors are intended to be traversed by an electric current. The grooves are intended to receive the coils 4. Heads 5 of these coils are formed outside the stator casing, at the ends thereof. A portion of at least one winding, in particular a winding head, comprises a plurality of disjoint or spaced apart beams of conductors and / or several disjoint or spaced apart conductors 51. The fact that several conductors or several bundles of conductors are disjoint or spaced makes it possible to pass between them, that is to say in the spaces 12, 13 which separate them, a coolant such as a gas, especially air , or a liquid, especially water or oil. In this way, a heat exchanger is produced that allows heat transfer from the conductors or the bundles of conductors to the coolant.

As represented in FIGS. 4 and 5, in a first variant embodiment, a coil comprises a head 5a in which the conductors 51 (or bundles of several conductors) are spaced apart and therefore separated by spaces 12. For example, the heat transfer fluid passing through this head moves generally radially relative to the stator, as represented by the arrows 11. Advantageously, as shown in FIG. 5, in a plane parallel to the direction of overall displacement of the coolant, the conductors (or bundles of several conductors ) are arranged in staggered or substantially staggered rows. In this head, the minimum distance between two conductors (or two beams of several conductors) is for example greater than 1 mm, preferably greater than 2 mm. Similarly, in this head, the maximum distance between two adjacent conductors (or two adjacent bundles of multiple conductors) is for example less than 4 mm, preferably less than 3 mm. It is clear that the arrangement of the different conductors and / or the different beams of several conductors and the dimensions of the spaces separating the different conductors and / or the different beams of several conductors can be optimized according to the geometry of the conductors and / or the conductor bundles and depending on the nature of the heat transfer fluid, in order to optimize the heat exchange between the conductors and / or the conductor bundles, on the one hand, and the heat transfer fluid on the other hand.

As represented in FIGS. 6 and 7, in a second variant embodiment, a coil comprises a head 5b in which bundles of several conductors are spaced apart and thus separated by spaces 13. For example, the heat transfer fluid passing through this head moves globally radially relative to the stator, as represented by the arrows 11. Advantageously, the conductor bundles form plies 52. These plies are separated by spaces 13. In this head 5b, the minimum distance between two plies of several conductors is for example greater at 1 mm, preferably greater than 2 mm. Similarly, in this head, the maximum distance between two adjacent sheets is for example less than 4 mm, preferably less than 3 mm. It is clear that the arrangement of the different plies and the dimensions of the spaces separating the different plies can be optimized as a function of the geometry of the plies and depending on the nature of the coolant, in order to optimize the heat exchange between the conductors and / or the driver bundles, on the one hand, and the coolant on the other hand.

The provision of ribbon conductors can be achieved by inserting a constant section object during winding.

The bundles of conductors may have other shapes than those of layers, in particular the form of strands. By "beam" is meant any configuration of conductors arranged parallel to each other or substantially parallel to each other in which the conductors are in contact with each other or substantially in contact with each other.

Advantageously, each stator winding comprises a head having a plurality of spaced apart beams of conductors and / or a plurality of spaced conductors 51. More preferably, each winding comprises two heads having a plurality of spaced beams of conductors and / or several spaced conductors 51, for example the two heads of each of the windings.

To guide the heat transfer fluid, the stator also comprises a heat transfer fluid channeling element: towards the spaced apart bundles of conductors and / or to the spaced conductors (51), and / or from the spaced apart bundles of conductors and / or from the conductors (51) spaced apart.

In the first variant described above, this pipe element 20 may comprise a single wall 8a. In the second variant described above, this pipe element may be constituted by the web 8b furthest from the stator frame. In this second variant, the pipe element may also comprise a single wall.

As shown in FIG. 8, a second motor embodiment 1 a differs from the first embodiment in that it comprises an element 7 for setting a heat transfer fluid in motion between the spaced beams of conductors and / or between the spaced apart conductors 51, for example a fan 7 for forcing a flow of air towards the heads previously described. Preferably, the motor comprises a fan at each of its ends at the winding heads. The fan or fans, for example each comprise a centrifugal wheel integral with the rotor 3.

As shown in FIGS. 9 and 10, a third embodiment of motor 1b differs from the first embodiment in that the stator comprises a housing 8 surrounding the head or heads. This housing forms one or more sealed cavities 9 intended to receive a coolant. Advantageously, a cavity 9 is formed at each head, that is to say at each winding head and the pipes 14, 15 guide a heat transfer fluid to each other cavities.

The invention has been described above applied to an electric machine stator, in particular an electric motor stator. Nevertheless, it is clear that the invention can also be applied to a wound rotor of an electric machine, in particular a wound rotor of an electric motor.

An electric machine according to the invention advantageously equips a motor vehicle.

The invention makes it possible to ensure excellent cooling of the electric machine. In fact, the material used to form electrical conductors, such as copper, are excellent electrical conductors, but also excellent thermal conductors (340 W / ° C / m against approximately 1 W / ° C / m for the resin and enamel protection of drivers). According to the invention, the electrical conductors are used to conduct the heat generated by the Joule effect in them according to the arrows 6 of Figure 3 to the heads where the heat is transmitted to a heat transfer fluid. At these heads, the heat exchanger makes it possible to effectively extract the heat from the winding and transfer it into the coolant without degrading the performance of the engine.

Thanks to the invention, the overall architecture of an electric machine must not be modified. In particular, the arrangement of the conductors in the notches is not modified. Thus, one can maintain a maximum filling of conductors to keep good performance of the machine. Compared to an electric machine known from the prior art, the arrangement of the conductors in the winding heads is modified: the conductors are spaced to allow the passage of the coolant (air or a liquid, such as oil having good dielectric properties). The heat generated in the conductors located in the notches is therefore conducted by the conductors to the winding heads, where a cooling fluid passes to evacuate the heat. The conductors can be electrically isolated by enamel. Their retention in the winding heads can be ensured by resin in the notches. Given the rigidity of the conductors, it is not necessary to embed the conductors in a resin in the winding heads and can therefore leave the electrically insulated conductors in direct contact with the heat transfer fluid.

As seen above, at the winding head, any type of conductor arrangement is possible to allow the cooling fluid to pass between the conductors.

The cooling performance obtained with the solution according to the invention is much greater than that obtained using the known solutions of the prior art.

If necessary, a deposit of a layer of resin may be applied to the conductors to protect them from the risk of mechanical attack during the flow of the cooling fluid. Resins can also be applied to certain parts of the conductors at the winding head to reinforce the mechanical structure of the conductors. This reinforcement is useful only if the conductors are thin, or if the length of conductors in suspension without contact with neighboring conductors is important. The electric machine according to the invention may be of variable reluctance type. This type of machine can be used to drive an electric vehicle or a hybrid vehicle.

In the case where the electric machine is integrated in a vehicle in a transmission system or close to a transmission system, the lubricating oil of the transmission system can be used as heat transfer fluid. This improves the integration of the solution.

In the same way, in the case where the electric machine is integrated in an electric or hybrid vehicle having a heat-transfer fluid system regulating the cabin and / or the battery and / or the electronics, it is possible to use this heat transfer fluid to thermally regulate the electric machine.

In the same way, in the case where the electric machine is integrated in a hybrid vehicle having a heat-transfer fluid system for thermal regulation of the heat engine, this heat transfer fluid can be used to thermally regulate the electric machine. The invention has been described applied to an electric motor stator. However, it can be applied in the same way to an electric motor rotor. It can still be applied to a stator or rotor of an electric machine other than an electric motor. 25 30

Claims (9)

1. An element (2) of electric machine (1) comprising a carcass (20) and a coil (4), characterized in that a head (5) of the coil comprises a plurality of spaced apart beams of conductors and / or several conductors (51) spaced apart. 2. Element according to the preceding claim, characterized in that it comprises, at the head, spaces (12; 13) between the spaced beams of conductors and / or between the spaced conductors (51), the spaces being by example between 1 mm and 4 mm, in particular between 2 mm and 3 mm. 3. Element according to one of the preceding claims, characterized in that the bundles comprise layers (52) of conductors. 4. Element according to one of the preceding claims, characterized in that the spaced apart beams and / or the spaced conductors are arranged in staggered rows. 5. Element according to one of the preceding claims, characterized in that it comprises a member (8; 8a; 8b) for channeling a coolant: to the spaced beams of conductors and / or to the conductors (51) spaced, and / or from the spaced beams of conductors and / or spaced conductors (51). 6. Element according to one of the preceding claims, characterized in that it comprises a housing (8) surrounding the head and intended to receive a heat transfer fluid. Electric machine, in particular an electric motor (1; 1a; 1b), in particular an electric motor vehicle engine, comprising an element according to one of the preceding claims. 8. Electrical machine according to the preceding claim, characterized in that it comprises a member (7) for moving a heat transfer fluid between the spaced apart beams of conductors and / or between the spaced conductors (51). 9. Motor vehicle comprising an electric machine according to claim 7 or 8.