Arrangement of a shaft and a housing

Abstract

An arrangement (1) comprises a housing (5), a shaft (3) rotatably mounted inside the housing (5), and a first electrically conductive element (7) integral with the housing (5) and extending along the axis of rotation (A) of the shaft (3). The arrangement includes a second electrically conductive element (9) of conical shape with axis (A), the first end (9a) of which has a cross-sectional diameter smaller than a second end (9b) and is in sliding contact with an end (7a) of the first conductive element (7). An oil guide element (11) is located radially above the shaft (3) and defines, with an inner wall (51) of the housing (5), a funnel whose lower opening extends radially above the first end (9a) of the second conductive element (9). The second conductive element is received inside a housing (30) in the shaft, and at least one channel (36) connects the housing to the external surface of the shaft. (See abstract figure: Figure 1)

Description

Title of the invention: Arrangement of a shaft and a housing

[0001] The invention relates to an arrangement of a shaft and a housing, comprising a housing, in particular a mechanical reducer housing, and a shaft, in particular a rotating electrical machine shaft, mounted for rotation inside the housing.

[0002] Rotating electrical machines, as is known per se, comprise a stator, fixed to a housing, and a rotor, fixed to a shaft. The rotor may be fixed to a driving and / or driven shaft and may belong to a rotating electrical machine in the form of an alternator or an electric motor. The housing of the electrical machine is configured to support the rotation of the rotor shaft by means of ball bearings, for example, made of steel.

[0003] During operation, the rotor accumulates static electricity like a capacitor and discharges it, generating electric arcs on the rotor teeth and bearing balls, which damages their surface and eventually leads to their destruction. It is therefore necessary to be able to connect the rotor to ground to prevent the generation of these electric arcs.

[0004] One solution is to use a conductive felt, as described in US20160010750. This felt extends radially from the shaft to the housing and ensures electrical contact between the shaft and the housing, the latter being grounded. However, felt is an expensive, fragile material that degrades over time and therefore loses effectiveness.

[0005] Another solution involves using brushes extending radially between the shaft and the gearbox housing, the latter being grounded. However, the friction generated by the brushes leads to a decrease in machine efficiency. To reduce friction, a single brush has also been positioned axially, in line with the shaft. This brush, fixed to the gearbox housing, has one end in sliding contact with the shaft.

[0006] Furthermore, an electric powertrain of a motor vehicle comprises a rotating electric machine and various mechanical parts, such as the mechanical gearbox that allows the speed ratio or torque between the input and output shafts of the motor to be changed. These mechanical parts require lubrication by a lubricating oil that forms a thin film between the mechanical parts, thus limiting friction between them and reducing wear. The gearbox is typically housed inside a casing, which may also house the rotating electric machine to form a geared motor. Alternatively, the gearbox casing may not include the rotating electric machine and may only house one end of the rotating electric machine's shaft. In In all cases, the shaft of the rotating electrical machine has splines that cooperate with at least one pinion forming part of the gearbox and requiring lubricating oil. This lubrication of the spline-pinion interface is achieved by supplying oil circulating inside the gearbox housing and penetrating the space between the splines and the pinion from their axial ends, which does not provide adequate lubrication of this interface.

[0007] There is therefore a need for an arrangement between a shaft and a housing which improves the lubrication of the shaft while allowing an electrical discharge of the shaft.

[0008] To this end, an arrangement of a shaft and a housing is proposed, comprising a housing, a shaft mounted for rotation inside the housing about an axis of rotation, and a first electrically conductive element integral with the housing extending along the axis of rotation of the shaft. The arrangement further comprises:

[0009] - a second electrically conductive element of conical shape with its axis coinciding with the axis of rotation of the shaft and having 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 conducting element, the second end being rotationally fixed to the shaft,

[0010] - an oil guide element located radially above the shaft, and defining with an inner wall of the casing a funnel whose lower opening opens radially above the first end of the second conductive element.

[0011] Furthermore, according to the invention, the tree exhibits:

[0012] - a housing with a shaft coinciding with the axis of rotation of the shaft, presenting a an opening located axially opposite the first conductive element and receiving the second conductive element.

[0013] - 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.

[0014] Thus, a feature of the invention lies in the implementation of a second electrically conductive element placed inside a housing made in the shaft to lubricate the external surface of the latter and to serve as an electrical contactor between the shaft and the housing via the first electrically conductive element.

[0015] The second conductive element thus transmits the electricity accumulated by the shaft to the first conductive element, which is electrically connected to the housing and to ground. Typically, the second conductive element can be made of an electrically conductive metallic material. The second conductive element can therefore be aluminum, copper, or any other conductive metal or alloy. Preferably, it is made of aluminum.

[0016] Furthermore, the second conductive element also allows the oil to be directed to at least one channel to lubricate the shaft. The guide element effectively collects the oil flowing from the housing and directs it to the second conductive element. The oil, guided by the guide element, thus falls onto the first end of the second conductive element and, since the second conductive element is rotationally fixed to the shaft, this rotation will carry the oil towards the second end of the second conductive element and then into at least one channel.

[0017] Advantageously, at least one channel can open inside the housing near the second end of the second conductive element. This allows the channel to be positioned as close as possible to, or at the level of, an area where oil will accumulate due to the conical shape of the second conductive element, thus sending a maximum amount of oil into the channel. This area corresponds to the contact zone between the housing and the second end of the second conductive element.

[0018] Advantageously, at least one channel can extend radially, which can facilitate the conveyance of oil from the housing to the external surface of the shaft.

[0019] Advantageously, the second conductive element can be press-fitted inside the shaft housing. This ensures good electrical contact between the shaft and the second conductive element.

[0020] The housing typically exhibits rotational symmetry. A cylindrical housing is advantageously produced, being simple to manufacture and ensuring good contact between the second end of the second conductive element and the shaft. Although not preferred, a conical or frustoconical housing, with a reduction in the diameter of the opening towards the bottom of the housing, is also possible. This housing advantageously presents, for example, a small apex angle, for example less than 8°.

[0021] Advantageously, the second conductive element may have a wall extending radially from its first end, sliding against the first conductive element, particularly its end. This wall improves electrical contact between the first end of the second conductive element and the first conductive element. It also limits the flow of oil to the contact area between the first and second conductive elements. Finally, this wall can facilitate the guidance of oil from the inner wall of the housing, forming a funnel with the guiding element, towards the first end of the second conductive element, especially when the wall extends along the line of the inner wall of the housing, and particularly along a radial lower portion of this inner wall.

[0022] Advantageously, the external surface of the shaft may have at least one groove into which at least one channel opens. This can provide an oil reservoir on the external surface of the shaft to improve lubrication. In particular, the external surface of the shaft may have splines, notably intended to cooperate with a reduction gear, and at least one groove may be located, and / or at least one channel may open, at the splines to ensure proper lubrication of the spline surface. Specifically, at least one groove may be located, and / or at least one channel may open, at the mid-axial length of the splines. Furthermore, at least one groove may extend over all or part of the periphery of the external surface, thus forming an annular groove in an axial plane.

[0023] One, two, or more channels may be provided connecting the housing to the external surface of the shaft. When two or more channels are present, they may be axially spaced, in particular regularly spaced, or located in the same radial plane and / or regularly distributed around the axis of rotation of the shaft. In particular, a regular axial and radial distribution ensures shaft stability by redistributing its mass around its axis of rotation, thus limiting the generation of vibrations during its rotation.

[0024] Advantageously, the external surface of the shaft may have splines, and at least one channel may open at the splines, for optimal lubrication of the interface between the splines and a gear intended to cooperate with the shaft splines. Thus, in one embodiment, the arrangement also includes a gear cooperating with said splines.

[0025] Advantageously, the first conductive element may comprise a body integral with the housing and provided with a recess, an electrically conductive brush extending along the direction of rotation of the shaft and received within the recess, and a spring exerting an axial force on the brush in the direction of the shaft. The spring makes it possible to exert sufficient force on the brush to maintain contact between the brush and the second conductive element. Typically, the brush may be made of a conductive material different from that of the second conductive element. Preferably, the brush is made of a carbon-based material, such as graphite or a carbon-containing composite.

[0026] To facilitate maintenance and the creation of the funnel shape, the housing may have a removable part forming a lid to which the first conductive element is attached, and the internal wall of the housing defining a funnel with the guiding element may be an internal wall of this removable part of the housing. This makes it possible, in particular, to implement the invention without having to modify the housing, but only its removable part.

[0027] The arrangement according to the invention thus makes it possible to lubricate and ground a shaft mounted to rotate within a housing.

[0028] Advantageously, the shaft of the arrangement according to the invention may be a shaft of a rotating electrical machine and have splines on its external face. The arrangement may include at least one pinion located inside the housing and cooperating with the splines of the shaft, and at least one channel of the shaft may open at the splines. The electrical machine may be a rotating electrical machine with axial or radial flux, advantageously with axial flux. The at least one pinion may be part of a gearbox, and the housing may be a gearbox housing.

[0029] The arrangement according to the invention is not limited to this application and can be implemented whenever a rotating shaft needs to be electrically connected to a housing and lubricated by oil present inside the housing.

[0030] Other features and advantages of the invention will become apparent from the following description of several particular embodiments of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:

[0031] [Fig-1] is a side sectional view of an arrangement of a shaft and a housing according to an embodiment of the invention.

[0032] [Fig.2] is a partial perspective view of the arrangement of [Fig.2] showing the oil guide element.

[0033] In this description, the terms "above," "superior," "below," and "lower" refer to a vertical direction corresponding to the direction of gravity, with the arrangement according to the invention in its operating position. The term "axial" refers to a direction coinciding with the axis of rotation A of the shaft, and the term "radial" refers to a direction perpendicular to the axis of rotation A of the shaft.

[0034] Fig. 1 represents an arrangement 1 according to an embodiment of the invention of a shaft 3 and a housing 5. This arrangement 1 therefore comprises a housing 5 and a shaft 3 mounted for rotation inside the housing 5.

[0035] The shaft 3 is here a shaft of a rotating electrical machine 2, partially shown in [Fig. 1]. The rotating electrical machine 2 includes, in particular, a housing 20 (partially shown) rotatably mounted on the shaft 3 via bearings 22, here ball bearings. The rotating electrical machine 2 also typically includes at least one rotor (not shown) fixed for rotation to the shaft 3 and at least one stator (not shown) free to rotate. These elements are well known and will not be described in further detail. The rotating electrical machine 2 may have axial flux or radial flux, preferably axial flux.

[0036] Typically, the shaft 3 of the rotating electrical machine is connected to a reduction gear 4 comprising at least one pinion 40. For this purpose, the shaft 3 has on its external face 32 of the splines 34 cooperating with the pinion 40, and located at the interface between the shaft 3 and the pinion 40.

[0037] The reducer 4 is housed here inside the casing 5, like the shaft 3. The casing 5 may or may not be integral with the casing 20 of the rotating electrical machine 2.

[0038] The housing 5 and the shaft 3 are typically metallic parts and can be made of any metal or alloy commonly used to manufacture housings and shafts, such as aluminum. Typically, the housing 5 is connected to ground.

[0039] The arrangement 1 also includes, inside the housing 5, a first electrically conductive element 7 attached to the housing 5 extending along the axis of rotation A of the shaft 3.

[0040] In the example shown, the first conductive element 7 comprises a body 70 fixed to the housing 5 and provided with a housing 72, and a conductive brush 74 extending along the direction of the axis of rotation A of the shaft 3 and received inside the housing 72. The first conductive element 7 also comprises a spring 76 exerting an axial force on the brush 74 in the direction of the shaft 3.

[0041] The body 70 and the brush 74 of the first element 7 are made of an electrically conductive material. The body 70 can be made of any conductive metal or alloy, such as aluminum. Preferably, it is made of the same material as the housing 5. The brush 74, for its part, can be a highly conductive and low-abrasive compound, generally carbon-based, such as graphite or a carbon-containing composite.

[0042] Thus, the first conductive element 7 allows the shaft 3 to be grounded by electrically connecting the shaft 3 and the housing 5, via the second conductive element 9 as described below, thus allowing the electrical discharge of the shaft 3 without generating electric arcs with the metallic elements surrounding the shaft.

[0043] The first conductive element 7, and in particular its body 70, may have a polygonal shape, preferably rectangular or square, cooperating with a complementary shape of the housing 5, thus preventing its rotation when the shaft 3 is rotated. The first conductive element 7, and in particular its body 70, may be secured to the housing 5 by any suitable means ensuring electrical contact, for example by simple fitting or by press fitting, by screwing, gluing with a conductive glue or otherwise.

[0044] The invention is of course not limited by the shape and / or structure of the first conductive element 7, provided that it is electrically conductive. Thus, the brush 74 could be received directly into a housing in the casing provided for this purpose.

[0045] According to the invention, the arrangement 1 further comprises, inside the housing 5, a second conductive element 9 and a guiding element 11. These elements, in co operation with the particular structure of the shaft 3 according to the invention, participate in the lubrication of the external surface 32 of the shaft 3.

[0046] The shaft 3 thus has a housing 30 whose axis coincides with the axis of rotation A of the shaft 3. The housing 30 has an opening 30a located axially opposite the first conductive element 7. The housing 30 receives the second electrically conductive element 9. This housing 30 advantageously has a simple cylindrical shape. A conical or frustoconical shape as described above is, however, conceivable, although not preferred.

[0047] The second electrically conductive element 9 is conical in shape with its axis coinciding with the axis of rotation A of the shaft 3. The second conductive element 9 has a first end 9a and a second end 9b. The first end 9a has a cross-section of smaller diameter than the second end 9b and is in sliding contact with an end 7a of the first conductive element 7. The second end 9b is rotationally fixed to the shaft 3. In particular, this second end 9b may be located near, or against, the bottom 30b of the housing 30 of the shaft 3, as shown in [Fig. 1].

[0048] The second conductive element 9 ensures electrical conduction between the shaft 3 and the first element 7. For this purpose, the second conductive element 9 is made of an electrically conductive material. It can be composed of any electrically conductive metal or alloy, such as aluminum, copper, or other materials. However, the choice of its material will advantageously be made according to the material of the first electrically conductive element 7, and in particular of the brush 74, with which it is in contact, in order to prevent and / or limit corrosion at the interface between these two elements.

[0049] To ensure better contact between the first element 7 and the second element 9, the latter may have a wall 90 extending radially on the side of its first end 9a, sliding against the end 7a of the first conductive element 7, here against the brush 74.

[0050] The second conductive element 9 is preferably press-fitted, for example by shrink fitting, inside the housing 30 of the shaft 3. However, it can also be secured to the shaft by any commonly used means ensuring electrical contact with the shaft, for example by welding or the use of conductive glue, or other.

[0051] According to the invention, the shaft 3 also has at least one channel 36 connecting the housing 30 to its external surface 32 and opening into the housing 30 between the second end 9b of the second conductive element 9 and the opening 30a of the housing 30.

[0052] To facilitate its construction and the flow of oil, at least one channel 36 extends advantageously radially. The at least one channel 36 may also have a cylindrical shape which can be easily produced by drilling in the shaft 3. The invention is not, however, limited to a particular shape of a channel and / or a particular orientation of a channel provided that the channel allows the oil to be conveyed from the housing to the outer face of the shaft.

[0053] It is preferable that at least one channel 36 opens into the housing 30 near the second end 9b of the second conductive element 9, in particular as close as possible to the contact area between this second end 9b and the housing 30. With this second end 9b obstructing the housing 30, the oil will tend to accumulate along the contact area between the second end 9b and the housing 30, ensuring an oil reserve allowing a continuous supply of oil to the channel(s) 36 opening into this area.

[0054] In the embodiment shown, at least one channel 36 opens at the splines 34 of the external surface 32 of the shaft 3, advantageously at mid-axial distance along the length of the splines 34 for better lubrication of the splines along their entire length (measured axially).

[0055] The shaft 3 may have two or more channels 36 distributed regularly around its periphery and / or axially spaced, 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 A to maintain a balance of the shaft's inertia. They are thus distributed angularly regularly around the second conducting element 9.

[0056] The oil is conveyed to the second conductive element 9 via the guide element 11, which is located above the shaft 3 radially (i.e. vertically), so that the oil falls onto the second conductive element under the effect of gravity.

[0057] As shown in Figures 1 and 2, the guide element 11 defines, with an inner wall 51 of the housing 5, a funnel 13, the lower opening of which 13a opens radially above the first end 9a of the second conductive element 9. In the example shown, the guide element 11 thus has two opposing lateral walls 110, 111, these walls being, on one side, connected to each other by a partially inclined lateral wall 112, and, on the other side, fixed to the inner wall 51 of the housing. The partially inclined lateral wall 112 is inclined towards the inner wall 51 in order to form the funnel shape 13 with it. Finally, the guide element 11 can be fixed to the inner wall 51 of the housing 5 by interlocking, welding, or otherwise.

[0058] Of course, the invention is not limited to a specific shape of the guide element 11 provided that it defines a general funnel shape 13 with the inner wall 51 of the housing. The guide element 11 could thus have a more rounded shape.

[0059] During the rotation of the shaft 3, the oil present inside the housing 5 (and used for the lubrication of the mechanical parts inside the housing) is projected against the inner wall of the housing 5, and in particular against the inner wall 50 located above the shaft 3, flows under the effect of gravity and its viscosity along this inner wall 50 and also along the inner wall 51 defining the funnel 13 with the guide element 11. The oil is thus collected by the guide element 11 and then flows from the opening 13a of the funnel 13 onto the first end 9a of the second conductive element 9. In order to facilitate this flow of the oil, the inner wall 51 of the housing 5 may advantageously have a radial lower portion 51a located radially above this first end 9a, in particular immediately above it.This arrangement of the internal wall 51 can be provided regardless of the embodiment of the guiding element 11 and / or the number, arrangement, and shape of the channel(s). Furthermore, the second conductive element 9 can advantageously be dimensioned so that its wall 90 extends in line with the part 51a, regardless of the embodiment of the arrangement according to the invention. Thus, the oil flowing through the opening 13a is not projected towards the first conductive element 7 and is guided towards the first end 9a of the second conductive element 9.

[0060] The conical shape of the second conductive element 9 then allows the oil to be conveyed from the first end 9a to the second end 9b. Indeed, as the second conductive element 9 is rotated, the oil will move along its surface due to centrifugal force and the oil's viscosity, from the first end 9a to the second end 9b. The apex angle of the conical shape of the second conductive element 9 can be chosen to optimize the oil flow along the surface, according to the dimensions of the housing. For example, a conical shape with an apex angle of 10° to 40°, preferably 20° to 30°, can be produced. The oil accumulated at this second end 9b is then discharged through the channel(s) 36 to the external surface 32 of the shaft 3, thus lubricating this surface.

[0061] In order to create an oil reservoir on the external surface 32 of the shaft (and thus at the shaft-pinion interface) and thereby improve the lubrication of this external surface, one or more grooves 38 may be formed on the external surface of the shaft 3, into which at least one channel 36 opens. The groove(s) 38 may be axial or non-axial, for example helical or otherwise, and / or extend over all or part of the periphery of the shaft. This embodiment can be combined with all the embodiments described.

[0062] In the example shown, and as can be seen more particularly in [Fig. 2], the part of the housing 5 which receives the first conductive element 7 and to which the element of The guide 11 forms a removable cover 52, which can be attached to the rest of the housing by screws (not shown). This cover 52 thus extends axially opposite the end of the shaft 3, which has the housing 30. This arrangement allows for quick and easy assembly / disassembly of the first conductive element 7, and also facilitates the replacement of the brush 74, the guide element, or another component, if necessary. This arrangement can be combined with all the embodiments described above.

Claims

Claims

1. Arrangement (1) of a shaft (3) and a casing (5), comprising a casing (5), a shaft (3) rotatably mounted inside the casing (5) about an axis of rotation (A) and a first electrically conductive element (7) integral with the casing (5) extending along the axis of rotation (A) of the shaft (3), characterized in that it comprises: - a second electrically conductive element (9) of conical shape with an axis coincident with the axis of rotation (A) of the shaft (3) and having a first end (9a) and a second end (9b), the first end (9a) having a cross-section of smaller diameter than the second end (9b) and being in sliding contact with one end (7a) of the first conductive element (7), the second end (9b) being integral in rotation with the shaft (3), - an oil guide element (11) located above the shaft (3) radi-ally,and defining with an internal wall (51) of the casing (5) a funnel (13) of which a lower opening (13a) opens radially above the first end (9a) of the second conductive element (9), and in that the shaft (3) has: - a housing (30) with an axis coincident with the axis of rotation (A) of the shaft (3), having an opening (30a) situated axially opposite the first conductive element (7) and receiving the second conductive element (9), - at least one channel (36) connecting the housing (30) to an external surface (32) of the shaft (3) and opening inside the housing (30) between the second end (9b) of the second conductive element (9) and the opening (30a) of the housing (30).,

2. Arrangement (1) according to claim 1, characterized in that the at least one channel (36) opens into the interior of the housing (30) near the second end (9b) of the second conductive element (9).

3. Arrangement (1) according to claim 1 or 2, characterized in that the at least one channel (36) extends radially.

4. Arrangement (1) according to any one of claims 1 to 3, characterized in that the second conductive element (9) is force-mounted inside the housing (30) of the shaft (3).

5. Arrangement (1) according to any one of claims 1 to 4, characterized in that the second conductive element (9) has a wall (90) extending radially on the side of its first end (9a), in sliding support against the first conductive element (7).

6. Arrangement (1) according to any one of claims 1 to 5, characterized in that the external surface (32) of the shaft (3) has at least one groove (38) inside which the at least one channel (36) opens.

7. Arrangement (1) according to any one of claims 1 to 6, characterized in that the shaft (3) has at least one of the following characteristics: - two or more channels (36) regularly distributed around the axis of rotation of the shaft, - two or more channels (36) axially spaced or located in the same radial plane.

8. Arrangement (1) according to any one of claims 1 to 7, characterized in that the first conductive element (7) comprises a body (70) integral with the casing (5) and provided with a housing (72), an electrically conductive brush (74) extending in the direction of rotation (A) of the shaft (3) and received inside the housing (72), and a spring (76) exerting an axial force on the brush (74) in the direction of the shaft (3).

9. Arrangement (1) according to any one of claims 1 to 8, characterized in that the casing (5) has a removable part (52) forming a cover to which the first conductive element (7) is secured, and the internal wall (51) of the casing defining a funnel with the guide element (11) is an internal wall of this removable casing part.

10. Arrangement (1) according to any one of claims 1 to 9, the shaft (3) being a shaft of a rotating electrical machine (2) and having splines (34) on its external face, and the arrangement further comprising at least one pinion (40) located inside the casing and cooperating with the splines (34) of the shaft and the at least one channel (36) of the shaft opening at the splines.

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