Oil diffuser

Abstract

The invention relates to an oil diffuser (10) comprising a diffuser body and sealing gaskets (12, 14), the diffuser further comprising a metal frame (15) axially positioned between the two sealing gaskets (12, 14). The invention also relates to an electrical machine comprising such an oil diffuser and an associated mounting method. Figure 2

Description

Title of the invention: Oil diffuser Technical field of the invention

[0001] The invention relates, in general, to the technical field of electrical machines, in particular for motor vehicles.

[0002] More particularly, the invention relates to cooling devices for an electrical machine. State of the prior art

[0003] Currently, the electrical machines that equip the powertrains of motor vehicles comprise active parts consisting mainly of a rotor and a stator. In one configuration, the stator comprises copper windings forming coils. The coils are cooled with oil via two oil diffusers of cylindrical shape of revolution placed on either side of the stator along a longitudinal axis of the latter.

[0004] Each of the oil diffusers is made of plastic and is provided at each end along the longitudinal axis of the stator with an axial seal. These axial seals ensure a seal of the oil circuit with respect to a casing containing at least the active parts of the electrical machine and the stator. Radial holes are made on a circumference of each oil diffuser. They allow the oil to be sprayed, during operation of the electrical machine, in the form of a spray onto each of the coils of said electrical machine. The oil is conveyed through a speed reducer to one of the two oil diffusers and then channeled to the other of the two oil diffusers through a series of longitudinal channels made in sheets forming different stacks of the stator.

[0005] The stator of the electrical machine, a fixed member of the active parts, provided with one of the two oil diffusers, is generally introduced inside a housing of the casing by a manufacturing process called "shrink fitting". This process, known per se, makes it possible to introduce, then by differential expansion, to immobilize in rotation the stator in the housing of the casing of the electrical machine. To do this, the casing is previously heated by induction to a temperature of the order of 200°C, which significantly increases an internal diameter of the housing in which the stator must be housed, in such a way that the latter can slide freely without any radial constraint. Thus, during a conventional assembly by this process, the casing is placed vertically and immobilized by clamping on a plate of a shrink fitting station.An expanding mandrel then grips the stator by an internal diameter, to come, by means of a sliding plate, to house it inside the associated housing of the . preheated crankcase. Preferably, the axial position of the stator is achieved using a shoulder, produced by machining in the crankcase housing. During assembly, the end of the stator carrying one of the two oil diffusers rests on this shoulder of the crankcase housing.

[0006] Machining such a shoulder within the stator housing is relatively expensive, given the tools and cycle times associated with producing it. Disclosure of the invention

[0007] The invention aims to remedy all or part of the drawbacks of the state of the art by proposing in particular a solution making it possible to avoid such a shoulder.

[0008] To do this, according to a first aspect of the invention, there is proposed an oil diffuser comprising a diffuser body and two seals, the diffuser further comprising a metal frame axially positioned between the two seals.

[0009] According to one embodiment, the diffuser body is overmolded onto the metal frame.

[0010] According to one embodiment, the metal frame comprises a series of slots arranged on a circumference of the metal frame.

[0011] According to one embodiment, the diffuser body comprises a series of radial holes facing the lights.

[0012] According to another aspect of the invention, there is provided an electrical machine comprising a casing comprising a housing, a stator positioned in the housing, the electrical machine comprising an oil diffuser having at least one of the preceding technical characteristics.

[0013] According to one embodiment, the housing comprising a bottom, the oil diffuser is sandwiched between the bottom and an associated end of the stator.

[0014] According to another aspect of the invention, there is provided a powertrain for a motor vehicle comprising an electric machine having at least one of the preceding technical characteristics.

[0015] According to yet another aspect of the invention, there is provided a motor vehicle comprising a powertrain having one of the preceding technical characteristics.

[0016] According to yet another aspect of the invention, there is provided a method of mounting the above electrical machine, the method comprising the following steps of: a. Assembling the oil diffuser onto the associated end of the stator; and, b. Performing a shrink-fitting operation to insert the assembled stator with the oil diffuser into the housing of the casing until the seal sealing comes to rest on the bottom of the casing. brief description of the figures

[0017] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: • [Fig.l]: a three-dimensional view of an electrical machine comprising an oil diffuser according to the invention; • [Fig.2]: a three-dimensional view of an oil diffuser frame according to the invention; • [Fig.3]: a three-dimensional view of an oil diffuser according to the invention comprising the frame of [Fig.2]; • [Fig.4]: a three-dimensional view of the stator of the electric machine of the [Fig.l] on which the oil diffuser of [Fig.3] is mounted; • [Fig.5]: a sectional view of the stator of [Fig.4] positioned in a housing of a casing of the electric machine of [Fig.l]; and • [Fig.6]: is a view of detail VI of [Fig.5].

[0018] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of an embodiment

[0019] [Fig.l] illustrates an electrical machine 1 intended to equip, for example, a powertrain of a motor vehicle. The electrical machine 1 comprises a casing 2 in which a housing 21 is provided for receiving active parts 3 and 5 of the electrical machine 1. The active parts 3 and 5 are, here, respectively a stator 3 and an associated rotor 5. As indicated in the preamble to the description, the stator is made of a series of stacks of sheets in an axial or longitudinal direction in which a series of longitudinal channels 32 are provided for conveying a cooling oil from one of the longitudinal ends of the stator 3 to the other of the longitudinal ends. This is illustrated in [Fig.4]. Furthermore, at each of the longitudinal ends, the stator comprises respectively a first oil diffuser 4 and a second oil diffuser 10.The oil diffuser 10 is, here, according to the invention and is sandwiched longitudinally between the stator 3 and a bottom 22 of the housing 21 (see [Fig.6]). In particular, the first 5 and second 10 oil diffusers each surround the buns 31 of their respective ends of the stator 3 to ensure cooling by oil projection during operation of the electrical machine 1.

[0020] With reference to Figures 2 and 3, we will describe in more detail the oil diffuser 10 according to the invention. The oil diffuser 10 according to the invention here comprises a metal frame 15 of truncated cone shape. The metal frame 15 comprises on a circumference a series of openings 16 uniformly distributed on said circumference of the frame 15. Here, the openings 16 are six in number. At each of the axial ends of the metal frame 15, the oil diffuser 10 according to the invention comprises an axial seal 12, 14. In addition, the oil diffuser 10 according to the invention comprises a diffuser body 11, here made of plastic material, which can be overmolded onto the metal frame 15. The diffuser body 11 comprises, in a manner known per se, a set of radial holes 13 distributed over a circumference of the diffuser body 11 opposite and through the openings 16 of the metal frame 15.

[0021] The shape of the oil diffuser 10 according to the invention may be different from that of the embodiment which has just been described, and in particular the structure of the metal frame of the oil diffuser 10 according to the invention.

[0022] With reference to Figures 4 to 6, we will briefly describe a method of mounting the stator 3 in the housing 2 of the casing 2 of the electrical machine 1.

[0023] Before a shrink fitting operation, the stator 3 comprising the stacks of sheets and the coils 31 of the copper windings is assembled with the oil diffuser 10 according to the invention as illustrated in [Fig.4]. The seal 14 is fixed on the associated end of the stator 3.

[0024] Then, the casing 2 is heated to approximately 200°C, which allows it to expand, and, in particular, to expand the housing 21 at least radially. Then, by a shrink-fitting operation known per se, the stator 3 equipped with the oil diffuser 10 according to the invention is introduced axially into the preheated housing 21, the oil diffuser 10 according to the invention being introduced first until the seal 12 comes to bear on the bottom 22 of the housing 21. Thus, the metal frame 15 of the oil diffuser 10 according to the invention allows said oil diffuser 10 according to the invention not to deform under the weight of the stator 3 (of the order of about twenty kilograms) and thus to allow optimal positioning of the stator 3 in the housing 21 of the casing 2 of the electrical machine 1.

[0025] With such an oil diffuser 10 according to the invention, it is no longer necessary to produce the shoulder of the prior art described in the preamble to the description inside the housing 21. This makes it possible to produce a less expensive electrical machine 1 whose casing 2 is simpler and quicker to produce.

[0026] Naturally, the invention is described in the foregoing by way of example. It is understood that the person skilled in the art is able to carry out different variant embodiments of the invention without departing from the scope of the invention.

[0027] It is emphasized that all features, as they emerge for a person skilled in the art from the present description, the drawings and the attached claims, even if concretely they have only been described in relation to other determined features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or meaningless.

Claims

Claims

1. Oil diffuser (10) comprising a diffuser body (11) and two seals (12, 14), characterized in that the diffuser further comprises a metal frame (15) axially positioned between the two seals (12, 14).

2. Diffuser according to claim 1, characterized in that the diffuser body is overmolded onto the metal frame.

3. Diffuser according to one of claims 1 to 2, characterized in that the metal frame comprises a series of lights (16) arranged on a circumference of the metal frame.

4. Diffuser according to claim 3, characterized in that the diffuser body comprises a series of radial holes (13) facing the lights (16).

5. Electrical machine (1) comprising a casing (2) comprising a housing (21), a stator (3) positioned in the housing (21), characterized in that the electrical machine comprises an oil diffuser (10) according to one of claims 1 to 4.

6. An electrical machine according to claim 5, characterized in that the housing comprising a bottom (22), the oil diffuser (10) is sandwiched between the bottom (22) and an associated end of the stator (3).

7. Powertrain for a motor vehicle, characterized in that it comprises an electric machine according to one of claims 5 QA

8. d U. Motor vehicle, characterized in that it comprises a powertrain according to claim 7.

9. Method for assembling the electrical machine according to claim 6, characterized in that the method comprises the following steps of: a. Assembling the oil diffuser (10) on the associated end of the stator (3); and, b. Carrying out a shrink-fitting operation to introduce the stator assembled with the oil diffuser into the housing (21) of the casing (2) until the seal (12) comes to bear on the bottom (22) of the casing.

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