Rotating electrical machine, in particular for a motor vehicle drive system

Abstract

The invention relates to a rotating electrical machine, in particular for a motor vehicle drive system, said machine comprising: a casing (1); a rotating element (10), rotatably mounted inside the casing (1) about an axis of rotation (X); a first electrically conductive element (5); and a sensor (4) for measuring one or more kinematic parameters of the rotating element (10), the first conductive element (5) being connected electrically to the casing (1). According to the invention, the sensor (4) is equipped with a through-hole (40) and the rotating element (10) and the first electrically conductive element (5) are in sliding contact with each other through said hole (40).

Description

Description Title of the invention: Rotating electrical machine, in particular for a motor vehicle engine

[0001] The invention relates to a rotating electrical machine. Although more particularly intended for a motor vehicle engine, the invention may however be applied in other fields.

[0002] Rotating electrical machines are known that include a stator, secured to a casing, and a rotor, secured to a shaft. During operation, the rotor becomes charged with static electricity and discharges, generating electric arcs between the rotor teeth and the ball bearing balls that allow the shaft to rotate in the casing. This damages the balls and, ultimately, leads to their destruction. It is therefore necessary to be able to connect the rotor to ground in order to avoid the generation of these electric arcs.

[0003] Various solutions have already been developed in this regard. One of them was the subject of a patent application filed in the name of the applicant, unpublished at the date of filing of the present application. It provides for a brush arranged axially, in the extension of the shaft, this brush, integral with the casing, having one end in sliding contact with the shaft.

[0004] It is also known to optimize the operation of rotating machines by controlling the angular position and / or rotational speed of the rotor. For this, inductive sensors are used. However, their positioning implies an increase in the size of the rotating machines equipped with them.

[0005] The invention aims to at least partially overcome the above drawbacks and to this end proposes a rotating electrical machine, in particular for a motor vehicle engine, said machine comprising a casing, a rotating assembly, mounted in rotation inside the casing around an axis of rotation, a first electrically conductive element and a sensor for measuring one or more kinematic quantities of said rotating assembly, said first conductive element being in electrical connection with said casing, said sensor having a passage orifice, said rotating assembly and said first electrically conductive element being in sliding contact with each other through said orifice.

[0006] Thanks to the first electrically conductive element, it is possible to electrically connect said rotating assembly to ground. In addition, the invention allows a limitation of the axial size of the machine by integrating a measuring sensor along said first electrically conductive element and / or said rotating assembly thanks to the orifice provided in the sensor for this purpose. Another advantage of the invention is make said sensor more easily accessible.

[0007] According to various additional characteristics of the invention, which may be taken together or separately and which form as many embodiments of the invention: - said kinematic quantities of said rotating equipment capable of being measured by the sensor are a speed and / or an angular position of said rotating equipment, - said rotating crew comprises a target configured to interact with said sensor, - said target comprises blades formed by angular sectors, - the number of angular sectors corresponds to a number of pairs of poles of said machine, - said sensor is an inductive sensor, - said sensor comprises inductive members configured to capture a variation in a magnetic field emitted by said sensor, said variation being a function of a passage of said angular sectors opposite said inductive members, - said sensor comprises a printed circuit board, - said inductive organs are fixed and electrically connected to said card, - said orifice is provided through said card, - said sensor comprises a housing, secured to the casing, - said housing is made of organic material, - said first conductive element is secured to the casing, directly or indirectly, - said first conductive element extends along the axis of rotation, - the first conductive element is integral with the sensor housing, - said sensor comprises an electrical conductor connecting said first conductive element and said casing, - said electrical conductor passes through said housing, - the first conductive element comprises a body, integral with the sensor housing, - said body is provided with a housing, said first conductive element further comprising an electrically conductive brush extending along the axis of rotation of said rotating assembly, said brush being received inside the housing, - said first conductive element further comprises a spring exerting an axial force on the brush in the direction of said rotating assembly, - said rotating assembly and said first electrically conductive element are in contact with each other at longitudinal ends, called contact ends, which face each other, said longitudinal contact ends are located in the vicinity of said orifice, said blades are located axially at the contact end of said rotating assembly so that an air gap between said target and the sensor is limited, said rotating assembly comprises a shaft and a second electrically conductive element, said target is mounted on said second electrically conductive element, the second electrically conductive element is conical in shape, centered on the axis of rotation, said second conductive element has a first end and a second end, the first end having a cross-section of smaller diameter than the second end and being in sliding contact with one end of the first conductive element, the second end being integral in rotation with the shaft,said machine comprises an oil guide element opening radially above the first end of the second conductive element, the shaft has a housing with an axis coincident with the axis of rotation of the rotating assembly, said housing of the shaft having an opening located axially opposite the target and receiving the second conductive element, the shaft has at least one channel connecting the housing to an external surface of the shaft and opening inside the housing between the second end of the second conductive element and the opening of the housing, the channel opens inside the housing near the second end of the second conductive element, the channel extends radially, the second conductive element is force-fitted inside the housing of the shaft, the second conductive element has a wall extending radially on the side of its first end, in sliding support against the first conductive element,the external surface of the shaft has grooves, said machine further comprises at least one pinion located inside the casing and cooperating with the grooves of the shaft, the channel of the shaft opens at the level of the grooves.,

[0008] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the detailed explanatory description which follows, of at least one embodiment of the invention given by way of purely illustrative and non-limiting example, with reference to the appended schematic drawings among which:

[0009] [Fig.l] schematically illustrates along a longitudinal sectional plane an embodiment of the rotating machine according to the invention;

[0010] [Fig.2] schematically illustrates in perspective a sensor and a longitudinal end of a rotating assembly of the machine according to [Fig.l],

[0011] As illustrated in [Fig.l], the invention relates to a rotating electrical machine. It is, for example, a rotating electrical machine for a motor vehicle with an electric motor operating, in particular, in traction and / or propulsion. Said machine is intended to be supplied with electric current from an energy storage unit, such as batteries, using a power supply circuit making it possible to convert a direct current generated by said storage unit into an alternating current for supplying the rotating machine.

[0012] Said machine comprises a casing 1 and a rotating assembly 10, mounted in rotation inside the casing 1 around an axis of rotation, referenced X. Said machine further comprises a first electrically conductive element 5 in electrical connection with said casing 1. Said first conductive element 5 is preferably fixed. In other words, unlike the rotating assembly 10, it is not driven in rotation. As will be detailed below, said rotating assembly 10 and said first electrical element 5 are in sliding contact with each other so as to allow the conduction of an electric current between them.

[0013] According to the illustrated embodiment, said rotating assembly 10 comprises a shaft 2 and a second electrically conductive element 3. Said rotating assembly 10, in particular said shaft 2, is mounted, for example, via bearings, in particular ball bearings (not illustrated) on the casing 1. The rotating electrical machine further comprises at least one rotor (not shown) integral in rotation with said rotating assembly 10, in particular with said shaft 2, and at least one stator (not shown) linked to the casing 1. The rotating electrical machine is axial flux or radial flux, preferably axial flux.

[0014] Said machine optionally comprises a reducer provided with at least one pinion 6. Said rotating assembly 10 is connected to the reducer by the pinion 6. For this purpose, said rotating assembly 10, in particular said shaft 2, has on an external face splines 60 cooperating with the pinion 6, and located at the interface between said rotating assembly 10 and the pinion 6.

[0015] The casing 1 of the rotating machine comprises, for example, a first part in in which the reducer is housed and a second part in which stator and rotor windings are mounted. The first and second parts are attached to each other. Alternatively, they are made from the same material as each other.

[0016] The casing 1 and the rotating assembly 10, in particular the shaft 2, are typically metal parts and may be made of any metal or alloy commonly used to manufacture casings and shafts, such as aluminum. The casing 5 is connected to ground.

[0017] The first electrically conductive element 5 extends, in particular, longitudinally, along the axis of rotation X, and / or radially around said axis of rotation X. It forms, for example, a grounding ring.

[0018] In the example shown, the first conductive element 5 comprises a body 52 defining a housing 50. Said first conductive element 5 further comprises an electrically conductive brush 51 extending along the axis of rotation X. Said brush is received inside the housing 50. Said first conductive element 5 further comprises a spring 53 exerting an axial force on the brush in the direction X so as to press said brush 51 against said rotating assembly 10. The electric current flowing in the brush 51 is conducted to a fixed end of the spring 53 opposite that acting on the brush 51.

[0019] The sliding contact mentioned above between said rotating assembly 10 and said first electrically conductive element 5 takes place at longitudinal ends, called contact ends, which face each other of said rotating assembly 10 and said first electrically conductive element 5, in particular of said brush 51. The contact zone C defined in this way is located at the axis of rotation X of the rotating assembly, that is to say, in a zone where the tangential speed of the rotating assembly 10 is minimum. The wear of the brush 51 is thus limited.

[0020] The brush 51 of the first element 5 is made of an electrically conductive material. Preferably, it is composed of a highly conductive and low-abrasive compound, generally carbon-based, such as graphite or a composite containing carbon. The brush 51 advantageously has a polygonal shape, in particular rectangular or square, cooperating with a fixed complementary shape of the rotating machine, thus preventing it from being driven in rotation when the rotating assembly 10 is rotated and ensuring the sliding of said rotating assembly 10 on said brush 51.

[0021] According to the invention, said rotating machine further comprises a sensor 4 for measuring one or more kinematic quantities of said rotating assembly 10, in particular its speed and / or its angular position. Said sensor 4 has a passage orifice 40 through which the sliding contact between said rotating assembly 10 and said first electrical element 5 takes place. Thanks to said orifice 40 and the passage therethrough of said rotating assembly 10 and / or said first conductive element 5, the sensor 4 does not add to the axial bulk of said rotating machine. Sensor 4 is also more easily accessible.

[0022] As illustrated in [Fig.2], said rotating assembly 10 comprises a target 33 configured to interact with said sensor. 4. Said target 33 is, for example, made of iron or steel. Said target 33 here comprises blades forming angular sectors, in particular in a number equal to a number of pairs of electrical poles of said machine. Said blades are located axially at the contact end of said rotating assembly 10 so that an air gap between said target 33 and the sensor 4 is limited.

[0023] Said sensor 4 is preferably an inductive sensor. In other words, said sensor 4 comprises inductive members (not illustrated) configured to capture a variation in a magnetic field emitted by said sensor 4. Said variation in the magnetic field is a function of the measurements to be carried out. Here, said variation is a function of a passage of said angular sectors opposite said inductive members.

[0024] More precisely, the inductive members generate a high-frequency signal reflected by the target 33, the number of blades of which is directly linked to the architecture of the rotor. The target 33 is formed, for example, of four blades, symmetrically distributed, corresponding to four pairs of rotor poles. The fact of having blade cutouts generates a disturbance of the high-frequency signal generated by the inductive members. The reading of the reflected signal is carried out by the sensor 4 and this signal makes it possible to know precisely the angular position and the rotation speed.

[0025] Said sensor 4 advantageously comprises a printed circuit board 43 (visible [Fig. 1]). Said inductive members are fixed and electrically connected to said board. Said sensor 4 further comprises electronic components, connected to said board, for converting the signal reflected by the blades in the form of an electric current representative of the speed and / or the angular position of said rotating assembly 10.

[0026] According to the illustrated embodiment, said sensor 4 comprises a housing 4L. Said housing 41 is advantageously secured to the casing 1, for example using screws. For this, said sensor 4 here comprises fixing flanges 45.

[0027] Said printed circuit board 43 is here fixed on said housing 4L. Said sensor also comprises a closing cover 42. Said printed circuit board is housed in a space located between said housing 41 and said closing cover 42. Said orifice 40 is provided through said board 43 as well as, here, through said housing 41 and said closing cover 42. In other words, said housing 41, said board 43 and said closing cover 42 have as many passages for said rotating assembly 10 and / or said first conductive element 5, said passages being located one after the other along said axis of rotation X to form said orifice 40 of the sensor 4.

[0028] Said sensor 4 advantageously comprises an electrical connector 46. It makes it possible to connect said sensor 4 to a current supply circuit for the components of said sensor and / or to a control circuit intended for transmission of the measurements taken by said sensor 4. Said connector 46 is formed, for example, in the housing 4L

[0029] If we refer again to [Fig.l], we see that said longitudinal contact ends of the first conductive element 5 and of said rotating assembly 10 are located in the vicinity of said orifice 40. More precisely, here, said first conductive element 5, in particular said brush 51, opens through said orifice 40 and said longitudinal contact ends are located slightly outside said housing 41 of the sensor 4, on the side of the casing 1.

[0030] The first electrically conductive element 5 is integral with the casing 1, directly or indirectly. In the illustrated embodiment, the first conductive element 5, in particular the body 52 of the first electrically conductive element 5, is integral with the housing 41 of the sensor 4 which, as already indicated, is integral with the casing 1.

[0031] According to a first embodiment, said housing 41 is made of organic material. To make the electrical connection between said first conductor 5 and said casing 1, said sensor 4 comprises an electrical conductor 44, preferably made of copper, connecting said first conductor 5 and said casing 1. In other words, here, the electrical conductor 44 is connected to the passage of the current coming from the brush 51 located at the fixed end of the spring 53, on the one hand, and / or, on the other hand, at a point on the casing 1, for example at one of the flanges 45 for fixing the sensor 4 to said casing 1.Said electrical conductor 44 passes along the body 52 of the first conductive element 5, under said cover 42 and through said housing 4L. By placing the end of said conductor 44, located on the side of the casing 1, between said casing 1 and said housing 41, close to one of the fixing flanges 45 of the sensor 4 on the casing 1, good plating of said connector 44 against said casing 1 is ensured and, consequently, a good electrical connection between these two components.

[0032] Alternatively, the housing 41 of the sensor 4 is made of an electrically conductive material, in particular iron or steel, alternatively copper or aluminum. The body 52 of the first element 5 is made of an electrically conductive material. The body 52 may be made of any conductive metal or alloy, such as aluminum. Preferably, it is made of the same material as the housing 41 and / or the casing 5.

[0033] Thus, in each of these variants, the first conductive element 5 makes it possible to ground the rotating assembly 10, via the sensor 4, by electrically connecting said rotating assembly 10 and the casing 1. The electrical discharge of the rotating assembly 10 without generating electric arcs with the metallic elements surrounding the latter is thus possible.

[0034] In the illustrated embodiment, the second conductive element 3 is received in a housing 23 of the shaft 2. Said housing 23 has a longitudinal axis coincident with the axis of rotation X of the rotating assembly and an opening 23a located axially opposite the target 33. This housing 23 of the shaft 2 advantageously has a cylindrical shape which is simple to produce. A conical or truncated conical shape is however conceivable.

[0035] The second conductive element 3 is, for example, of conical shape with an axis coincident with the axis of rotation X of the rotating assembly. The second conductive element 3 makes it possible in particular to ensure electrical conduction between the shaft 2 and the first element 5. For this purpose, the second conductive element 3 is made of an electrically conductive material. It can be composed of any electrically conductive metal or alloy, such as aluminum, copper or other. However, the choice of its material will advantageously be made according to the material of the first electrically conductive element 5, and in particular of the brush 51, with which it is in contact to avoid and / or limit corrosion at the interface between these two elements. The second conductive element 3 has a first end and a second end 3b.

[0036] The first end has a cross-section of smaller diameter than the second end 3b. Said first end of the second conductive element 3 here forms the contact end of the rotating assembly 10 mentioned above and is therefore located at the contact zone C. In other words, said first end of the second conductive element 3 is in sliding contact with the contact end of the first conductive element 5, namely the end located opposite the brush 51. Said contact ends preferably have similar dimensions. For example, a diameter of said first end of the second conductive element 3 is substantially equal to a dimension of one side of the brush 51 so that said first end of the second conductive element 3 is inscribed in the end opposite the brush 51.

[0037] Said target 33 is here mounted on said second electrically conductive element 3, for example by shrink fitting. Said target 3 comprises for this purpose an annular plate 31 (better visible [Fig.2]) fixed to said second electrically conductive element 3. The blades of the target 33 extend radially from said plate 31.

[0038] The second end 3b of the second conductive element 3 is rotationally integral with the shaft 2. In particular, this second end 3b may be located near, or against, a bottom of the housing 23 of the shaft 2. The second conductive element 3 is preferably force-mounted, for example by shrinking, inside the housing 23 of the shaft 3, in particular by means of a shrinking zone 30 located near said second end 3b of the second conductive element 3. However, it may also be secured to the shaft by any means ensuring electrical contact with the shaft, for example by welding or the use of a glue driver, or other.

[0039] According to the invention, the shaft 2 also has at least one channel 21 connecting the housing 23 to an external surface of the shaft and opening inside the housing 23 between the second end 3b of the second conductive element 3 and the opening 23a of the housing 23.

[0040] To facilitate its production and the flow of oil, said channel(s) 21 advantageously extend radially. They possibly have a cylindrical shape which can be easily produced by drilling into the shaft 2. The invention is however not limited to a particular channel shape and / or to a particular orientation of the channels provided that the channels allow the oil to be conveyed from the housing 23 to the external face of the shaft 2.

[0041] It is preferable for said channel(s) 21 to open into the interior of the housing 23 near the second end 3b of the second conductive element 3, in particular as close as possible to the hooping zone 30. Indeed, said second end 3b obstructing the housing 23 at this level, the oil will tend to accumulate near said hooping zone 30, ensuring an oil reserve allowing a continuous supply of oil to the channel(s) 21 opening into the vicinity of this zone.

[0042] In the embodiment shown, the channel(s) 21 open at the level of the grooves 60 formed on the external surface of the shaft 3, advantageously at mid-distance axially of the length of the grooves 60 for better lubrication of the grooves over their entire length (measured axially).

[0043] The channels 21 are, for example, distributed regularly around the periphery of the shaft 3 and / or spaced axially, preferably regularly spaced. Preferably, the shaft 3 has two or three of them, advantageously arranged in the same axial plane, and distributed regularly around the axis X to maintain a balance of the inertia of the shaft. They are thus distributed angularly regularly around the second conductive element 3.

[0044] Said machine advantageously comprises an oil guide element 71 opening radially above the first end of the second conductive element 3. Said guide element 71 is here connected to an internal space 7, bathed in oil, of the casing 1.

[0045] Said second conductive element 3 has a cone 32 for routing the oil between its first end and said hooping zone 30. The conical shape of the second conductive element 3 makes it possible to convey the oil coming from the guide circuit 71 to the conduits 21. Indeed, the second conductive element 3 being in rotation, the oil will move along the surface of this second element 3 thanks to the centrifugal force and the viscosity of the oil from the first end in the direction of the second end 3b. The apex angle of the conical shape of the second conductive element 3 may be chosen so as to optimize the path of the oil along the surface and according to the dimensions of the housing 23. For example, a conical shape with an apex angle of 10° to 40°, preferably 20° to 30°, may be produced. The oil accumulated at this second end 3b is then evacuated through the channel(s) 21 towards the external surface of the shaft 3 and the splines 60, ensuring their lubrication.

[0046] The invention is of course not limited by a shape and / or a structure of the first conductive element 5, provided that it is electrically conductive, nor to a shape and / or a structure of the sensor 4. Thus, the brush 51 and / or the measuring components of the sensor 4 could be received directly in one or more housings of the casing 1 provided for this purpose.

Claims

Claims

1. Rotating electrical machine, in particular for a motor vehicle engine, said machine comprising a casing (1), a rotating assembly (10), mounted in rotation inside the casing (1) around an axis of rotation (X), a first electrically conductive element (5) and a sensor (4) for measuring one or more kinematic quantities of said rotating assembly (10), said first conductive element (5) being in electrical connection with said casing (1), said sensor (4) having a passage orifice (40), said rotating assembly (10) and said first electrically conductive element (5) being in sliding contact with each other through said orifice (40).

2. Machine according to the preceding claim in which said kinematic quantities of said rotating assembly (10) measured by the sensor (4) are a speed and / or an angular position of said rotating assembly (10).

3. Machine according to any one of the preceding claims in which said rotating assembly (10) comprises a target (33) configured to interact with said sensor (4), said target (33) comprising blades formed by angular sectors.

4. Machine according to any one of the preceding claims wherein said sensor (4) is an inductive sensor.

5. A machine according to any preceding claim wherein said sensor (4) comprises a printed circuit board (43), said orifice (40) being provided through said board (43).

6. Machine according to any one of the preceding claims in which said sensor (4) comprises a housing (41), integral with the casing (1), said housing (41) being made of organic material, the first conductive element (5) being integral with said housing (41), said sensor (4) comprising an electrical conductor (44) connecting said first conductive element (5) and said casing (1), said electrical conductor (44) passing through said housing (41).

7. Machine according to any one of the preceding claims in which said rotating assembly (10) and said first electrically conductive element (5) are in contact with each other at longitudinal ends, called contact ends, which face each other, said longitudinal contact ends being located in the vicinity of said orifice (40).

8. Machine according to the preceding claim taken in combination with the claim 3 wherein said blades are located axially at the contact end of said rotating assembly (10) so that an air gap between said target (33) and the sensor (4) is limited.

9. Machine according to any one of the preceding claims in which said rotating assembly (10) comprises a shaft (2) and a second electrically conductive element (3) having a first end and a second end (3b), said first end being in sliding contact with the first conductive element (5), the second end (3b) being integral in rotation with the shaft (2).

10. Machine according to the preceding claim taken in combination with claim 3 in which said target (33) is mounted on said second electrically conductive element (3).

Images