Lubrication system for electric motor set with magnet and calibrated passage between oil reservoirs

Abstract

Vehicle power unit comprising an electric machine (1) and a transmission (TR) with a differential (DIF) and a ring gear (3) providing a lubricating oil lifting function, the electric machine compartment comprising a first oil reservoir (VM) and the transmission compartment comprising a second oil reservoir (VT), the housing having a wall passage (6) connecting the second oil reservoir to the first oil reservoir, the power unit comprising an oil pump (5) supplying a lubrication circuit, a multi-function insert (7) sealing the wall passage and comprising a calibrated passage hole (8) defining a predefined passage cross-section between the second oil reservoir and the first oil reservoir, a magnet (2) housed and held between forms formed from the housing and the receiving elements of the multi-function insert. Figure 2

Description

Title of the invention: Lubrication system for a motor-driven set with a magnet and calibrated passage between oil reservoirs

[0001] The present invention relates to an electric motor unit for a motor vehicle and its lubrication system. The electric motor unit comprises an electric machine and a differential transmission. The electric motor unit includes, on the one hand, an electrically driven oil pump and, on the other hand, an oil lifting function obtained by rotating the differential input wheel, also referred to as the ring gear in this document.

[0002] The electric machine is cooled when necessary by means of a pressurized oil circulation supplied by the pump. This same oil lubricates all the transmission components, the gears, the bevel gears, the bearings, the bushings, etc...

[0003] An interior space is provided which houses the electric machine and another interior space is provided which houses the transmission, separated by a casing wall.

[0004] A first oil reservoir is provided on the electrical machine side and a second oil reservoir on the transmission side. The first oil reservoir is connected to the second oil reservoir by a passage which will be the focus of the discussion here.

[0005] For the oil lifting function, the differential ring lifts oil from the second oil reservoir. Regarding the pressurized oil circuit, the strainer connected to the electric oil pump draws oil from the first oil reservoir.

[0006] The electric motor unit is arranged in a transverse configuration in the front or rear engine compartment of the vehicle, it drives one of the axles of the vehicle.

[0007] There are dynamic situations where a centrifugal force tends to move the oil to the right, i.e., towards the electric motor, or conversely, other situations where the centrifugal force tends to move the oil to the left, i.e., towards the transmission. Of course, left and right can be reversed depending on the arrangement of the electromotor unit along the transverse Y-axis.

[0008] It is common practice to place a magnet on the oil circuit to trap and collect residues / waste from the manufacturing process, as well as particles that detach when generated during operation, and even metallic pollutants introduced into the oil.

[0009] Furthermore, there are situations in life where the electric oil pump is not operating while the transmission is running, and conversely there are also situations of life where the electric oil pump is running while the transmission is not turning.

[0010] It is in this context that the inventors sought to propose a solution which allows relevant management of oil volumes in static and dynamic conditions, according to different life situations, paying particular attention to the cost of the solution and also to the weight.

[0011] To this end, an electric motor unit is proposed comprising an electric machine and a transmission, the transmission comprising at least one differential with a ring gear and providing a lubricating oil lifting function, the electric motor unit comprising a housing separating an electric machine compartment from a transmission compartment, the electric machine compartment comprising a first oil reservoir and the transmission compartment comprising a second oil reservoir, the housing having a wall penetration, obtained by casting, connecting the second oil reservoir to the first oil reservoir, the electric motor unit comprising: - an oil pump, configured to supply a high-pressure lubrication circuit, capable at least of cooling the electric machine and delivering pressurized oil to the transmission elements,- a multi-function insert, generally used to seal the wall opening, comprising a calibrated passage hole and receiving elements configured to receive a magnet; the calibrated passage hole defining a predefined passage section between the second and first oil reservoirs; - a magnet housed and held between shapes formed from the crankcase and the receiving elements of the multi-function insert.

[0012] Thanks to the provisions promoted above, the multi-function insert cleverly combines a calibrated section communication function between the first oil reservoir and the second oil reservoir as well as a function for maintaining the particle trapping magnet.

[0013] Under the term "obtained from casting" with respect to the lower wall passage, it must be understood that there is no machining rework at this location.

[0014] For the purposes of this description, the term "oil reservoir" refers to a hollow area in the lower part of the crankcase designed to receive oil by gravity; it designates the oil receptacle. In practice, before the electric motor unit is filled with oil, the first and second oil reservoirs are empty. During operation, the oil reservoirs are replenished by oil runoff that naturally returns to the lower part of the crankcase by gravity. The current oil level in the reservoirs depends on the operating lubrication conditions.

[0015] The wall passage is a through passage in the lower part which connects the electrical machine compartment with the transmission compartment for the lubrication system as will be seen later.

[0016] The oil pump is an electrically driven oil pump, meaning that it is equipped with an electric motor that drives the oil pump impeller / turbine. This motor is selectively controlled by a control unit, for example, according to the cooling requirement.

[0017] It is noted that the lubricating oil lifting function is carried out where there is a small radial gap left free between the differential ring and the differential housing; there is no pump element here as such.

[0018] The use of the multi-function insert having the calibrated passage hole makes it possible to release the constraints on the shape and section of the wall passage obtained from casting, which can then present a wider passage section which contributes to the overall lightening of the electromotor unit.

[0019] The function of the magnet is to trap particles with a metallic component that are transported by the circulating oil flow. It should be noted that the housing is made of aluminum and does not interfere with the effectiveness of the magnetic field created by the magnet.

[0020] According to one embodiment, when the electric oil pump is in operation, a first oil circuit Cl is established in which the magnet is positioned upstream of the calibrated passage hole, and when the electric pump is not in operation and the differential ring is rotating, a second oil circuit C2 is established in which the magnet is positioned upstream of the lifting zone provided by the ring.

[0021] The filtering and trapping effect provided by the magnetic field of the magnet thus makes it possible to treat the entire hydraulic flow which will be sent back upwards and in particular towards the elements to be lubricated, whatever the operating conditions.

[0022] Furthermore, in a static situation, that is, when the electric oil pump is not running and the differential ring gear is not rotating, with the vehicle substantially parked on a level surface, the axis of the calibrated passage hole is located below the general upper oil level. The two oil reservoirs then share the same upper oil level thanks to the communicating vessel function provided by the calibrated passage hole.

[0023] It is noted that during operation, the levels decrease and can be different between the first reserve and the second reserve.

[0024] According to one embodiment, the multi-function insert comprises on the one hand an insert body which rests at least in part on the edge of the wall passage and on the other hand one or more retaining elements.

[0025] The body of the insert is typically in the shape of a plate.

[0026] The calibrated through hole is made in the insert body.

[0027] According to one embodiment, the retaining elements include at least one fixing tab bearing on an edge of the wall passage and / or at least one S-shaped tab bearing on an edge of the wall passage.

[0028] The tabs and / or S-shaped tabs are configured to position and firmly hold the multifunction insert at the point of penetration through the wall. On one side, the body of the multifunction insert rests against the edge of the penetration, and on the other side, the ends of the tabs and / or S-shaped tabs hook onto the penetration.

[0029] According to a preferred embodiment, 2 fixing tabs and two S-shaped tabs are provided. One or more positioning locating points may also be provided.

[0030] According to one embodiment, the multi-function insert is inserted into the wall penetration by a translation along the transverse Y direction. The tabs and / or S-shaped lugs flex during the passage and return at the end of the translation to their rest position, thus achieving the desired anchoring. The multi-function insert is removable.

[0031] It is noted that the multifunction insert is inserted from the transmission compartment, which offers good access when the transmission-side crankcase cover is not in place.

[0032] According to one embodiment, the multi-function insert is made of plastic, preferably polyamide reinforced with fibers. For example, PA66 with GF35 fiber reinforcement could be chosen.

[0033] Complex shapes can be obtained from molding, in particular the retaining elements such as the more or less complex tabs and hooks, as well as the receiving elements for the magnet.

[0034] Advantageously, the multi-function insert is made in one piece entirely from material.

[0035] According to an alternative embodiment, the multi-function insert can be made of metal, for example by cutting and bending a sheet metal blank.

[0036] According to one embodiment, the calibrated passage hole is circular and has a diameter D8 between 4 mm and 8 mm. The inventors conducted simulations and tests to verify the damping effect of such a passage cross-section, which limits the flow rate from one oil reservoir to the other in the presence of centrifugal force. However, this hole allows sufficient flow for the first lubrication circuit when the pump is running and supplying the transmission compartment, as the oil return passes through the calibrated passage hole in this case.

[0037] According to one embodiment, the wall passage obtained from casting has a passage section at least 3 times greater than the passage section provided by the calibrated passage hole.

[0038] It should be noted that if the tests lead to the need to modify the cross-section of the calibrated hole, this does not call into question the casting of the housing, which would have been the case if the hole had been made directly in the casting of the housing. It is easier and more practical to modify the multi-function insert than to modify the housing of the generator set.

[0039] According to one embodiment, the electromotor unit further comprises a housing cover, and the magnet is further held by at least one rib formed in the housing cover. Closing the cover immobilizes the magnet along the transverse Y direction.

[0040] According to one embodiment, the receiving elements are L-shaped, U-shaped, or wedge-shaped walls. These receiving elements, in combination with those present on the housing casting, make it possible to visibly and intuitively delimit the housing for the magnet and frame the magnet. Thanks to these receiving elements, the magnet mounting is intuitive, and they provide a pre-retaining function for the magnet before the transmission housing cover is closed.

[0041] According to one embodiment, at least one guide rib is provided at the bottom of the housing, which facilitates the installation of the insert. A corresponding notch is provided in the bottom of the multifunction insert. The rib provides visual and physical guidance for mounting the insert in the wall opening.

[0042] The present invention also relates to an electric or hybrid vehicle, comprising at least one electromotor unit as described above.

[0043] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates an electric vehicle in top view with the electromotor unit mounted transversely; - [Fig.2] illustrates a schematic cross-section of the electromotor unit according to a generally vertical cross-section, with the electrical machine compartment shown on the right and the transmission compartment shown on the left; - [Fig.3] illustrates a schematic detail view of the wall passage between the transmission compartment and the electrical machine compartment, the multifunction insert not yet being installed, the view being taken according to the arrow III-III visible in [Fig.2]; - [Fig. 4] shows a perspective view of an example of an insert multifunctional according to the present invention; - [Fig.5] is analogous to [Fig.3] and illustrates the wall passage area equipped with the multi-function insert and magnet; - [Fig.6] is analogous to [Fig.3] and illustrates the area of ​​the wall passage equipped with the multifunction insert, the magnet being removed with the oil circulations around the magnet; - [Fig.7] illustrates a schematic vertical cross-section of the insert area multifunction, the differential ring is not shown and the transmission side casing cover is not closed; - [Fig.8] illustrates a schematic cross-section of the multifunction insert area, along the section line VIII-VIII visible in [Fig.5]; - [Fig.9] illustrates a front view of the multifunction insert from the side facing towards the electrical machine compartment.

[0044] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale, in particular the gaps and intervals.

[0045] Figure 1 shows a VH vehicle in top view. In the illustrated example, this vehicle comprises an electric motor unit located in the front engine compartment, with an electric traction machine 1 located on the right side of the electric motor unit and a transmission TR located on the left side of the electric motor unit.

[0046] Of course, the arrangement could be reversed, with the machine on the left and the transmission on the right. Alternatively, the electric motor unit could interact with the rear axle of the vehicle. The electric motor unit can be installed in conjunction with a steering or non-steering axle.

[0047] In the figures, the vehicle and its electromotor unit are located with respect to an orthogonal frame of reference as follows: the vertical direction is noted Z, the horizontal direction called longitudinal is noted X, the horizontal direction called transverse is noted Y.

[0048] The TR transmission includes a RED reduction gear and a DIF differential. The lubrication system equipping the electric motor unit will be discussed in the following paragraphs.

[0049] In the illustrated example, the electric motor 1 provides torque which enters the transmission, to be distributed to the two wheels of the axle via the differential DIF. At the output of the transmission TR, there are two wheel shafts, one connected to the left wheel and the other connected to the right wheel of the vehicle (not shown).

[0050] Regarding the reducer, as known in itself and not described in detail, there is provided an intermediate double pinion 61 which is driven by an output pinion of the electric machine and which in turn drives the ring 3 of the differential.

[0051] As can be seen in [Fig. 2], this intermediate gear 61 comprises a first pinion of large diameter and a second pinion of small diameter fixed to the first pinion. The second pinion is permanently engaged with the teeth 31 of the differential ring gear 3.

[0052] The differential DIF comprises a ring gear 3 and a mechanism body 32 which contains the planetary and satellite gears as known per se. The ring gear 3 forms the input wheel of the differential. It should be noted here that the ring gear's drive is parallel; it is not a bevel gear. The ring gear 3 is provided with teeth 31. In the illustrated example, the teeth are helical; they are not parallel to the axis.

[0053] The rotor of the electric motor rotates around the axis Al. The rotor of the electric motor is rotationally fixed to a primary pinion permanently engaged with the large pinion of the intermediate gear 61.

[0054] The crown 3 rotates about an axis labeled A3. The intermediate gear 61 rotates about an axis labeled A2. The axes A1, A2 and A3 are parallel.

[0055] The electromotor unit comprises a main housing 4.

[0056] The casing 4 delimits an internal space 4M which houses the electric machine and another internal space 4T which houses the transmission.

[0057] In other words, the casing 4 delimits an electrical machine compartment in relation to the transmission compartment, the two compartments are generally separated by a casing wall.

[0058] The housing 4 is made of aluminum and does not interfere with the effectiveness of the magnetic field created by the magnet. It is provided with a cover 42 on the machine side and a cover 41 on the transmission side. The housing 4 can be made in one piece or in several pieces assembled together.

[0059] The electric motor unit includes an oil pump 5 which is the driving element of a first lubrication circuit, labeled Cl. The oil pump is electrically driven. The oil pump supplies pressurized oil to the core of the electric machine, the circuit Cl being shown schematically in [Fig. 2]. In addition, a heat exchanger, not shown in the figures, is provided on the first oil circuit Cl.

[0060] Furthermore, an oil lifting function is provided, obtained by means of the rotation of the teeth 31 of the ring 3. The oil lifting function is part of a second lubrication circuit designated C2, the circuit C2 being schematically shown in [Fig.2].

[0061] Furthermore, the second lubrication circuit provides a trough 9, also called a multi-function reservoir trough. This trough forms a buffer oil reservoir; during lubrication operation, the trough 9 is continuously supplied by the lift or the electric oil pump and simultaneously discharges oil onto the relevant parts through orifices.

[0062] In the second lubrication circuit C2, there is no specific filter per se, but a magnet 2 is provided to trap metallic particles that might circulate in the oil. The position of this magnet 2 will be discussed later.

[0063] A first oil reservoir VM is provided on the electrical machine side and a second oil reservoir VT on the transmission side. The first oil reservoir is in Communication with the second oil reservoir is via a passage that will be discussed later. Regarding the pressurized oil circuit, the strainer connected to the electric oil pump draws oil from the first oil reservoir. An oil filter is provided near the strainer or pump to supplement the filtering effect provided by magnet 2.

[0064] The housing includes a wall passage 6, obtained by casting, connecting the second oil reservoir VT to the first oil reservoir VM.

[0065] There are dynamic situations where a centrifugal force FC1 (see figures 1 and 2) tends to move the oil to the right, i.e. towards the electric machine, or conversely other situations where the centrifugal force FC2 tends to move the oil to the left, i.e. towards the transmission.

[0066] Under the effect of inertial forces, the oil moves from one reservoir to the other through a communicating passage.

[0067] According to an advantageous feature of the present invention, the electromotor unit includes a multi-function insert 7 which generally closes the wall passage 6. This part is called an 'insert' because it is inserted in a position provided for this purpose in the wall passage 6; it can be removed if necessary and is therefore removable.

[0068] This part is described as multifunctional because on the one hand it defines the passage of oil between the two oil reservoirs and on the other hand it contributes to housing and maintaining the particle trapping magnet.

[0069] The multi-function insert 7 includes a calibrated through hole 8.

[0070] The calibrated passage hole defines a predefined passage section between the second oil reservoir VT and the first oil reservoir VM.

[0071] According to one option, the calibrated through hole is circular. According to one embodiment, the diameter D8 is between 4 mm and 8 mm.

[0072] It is noted that the shape of the passage hole could be other than circular, for example a substantially rectangular window.

[0073] When the vehicle travels on a curved road and a centrifugal force prevails to the right FC1, the transfer of oil through the calibrated hole 8 is limited in flow and prevents the second oil reservoir VT from drying out quickly.

[0074] Similarly, in the other direction, when a left-hand centrifugal force FC2 prevails, the transfer of oil through the calibrated hole 8 is limited in flow and prevents the first oil reservoir VM from drying out quickly.

[0075] There is no other passage for the oil between the two reservoirs at the bottom of the crankcase than the calibrated hole 8.

[0076] Furthermore, the multi-function insert 7 also includes reception elements 24 configured to receive a magnet 2.

[0077] The multi-function insert comprises an insert body 70. The insert body bears at least partially on the edge 47 of the wall opening (see [Fig. 8]). The insert body 70 closes the wall opening except for the calibrated hole 8. The thickness E7 of the insert body 70, for example from 1.5 to 3 mm, is less than the thickness L1 of the housing wall.

[0078] The multi-function insert includes retaining elements for holding said insert in the wall passage area 6.

[0079] In the example shown in [Fig.4], the retaining elements include two fixing tabs 71,72 bearing on an edge 49 of the wall passage and two S-shaped tabs 73,74 bearing on an edge 49 of the wall passage.

[0080] The number of tabs and / or S-shaped legs or equivalent may of course be different.

[0081] It is noted that any other means of clipping and / or holding the multifunction insert 7 in the wall passage 6 could be used within the framework of the present invention.

[0082] For the function of housing and holding the magnet 2, the multi-function insert 7 includes retaining elements. In the illustrated example, these are L-shaped, U-shaped, or wedge-shaped walls 24. The walls 24 protrude from the plate body 70.

[0083] The multi-function insert 7 is made of plastic. In the illustrated example, preferably polyamide reinforced with reinforcing fibers is chosen, for example PA6-6 grade GF35.

[0084] All the necessary shapes can be obtained directly from the mold that forms the multi-function insert part, including the retaining elements on the housing and also the receiving elements that allow the magnet 2 to be housed.

[0085] However, it is not excluded to form the multifunctional insert out of metal.

[0086] According to one option, the maximum dimension of the insert is 25 mm, the thickness of the body 70 is 3 to 4 mm, and it is understood that the dimensions mentioned are not limiting.

[0087] In the lower wall of the housing, two ribs 45, 46 are provided against which the magnet rests. These ribs act as spacers to keep the magnet away from the bottom wall of the housing. These ribs are cast and do not require any further processing.

[0088] It is noted that opposite the rib 46, a notch 78 is provided in the insert body, which allows for guidance during insertion. A locating 79, with a recessed shape in the housing, is also provided in the insert body for positioning.

[0089] As shown in [Fig. 5], the housing also includes side walls 64 which complement the reception elements provided on the multifunction insert. Preferably, these side walls 64 are cast without further machining.

[0090] Figure 9 illustrates another example of its multifunctionality with three similar tabs 71, 72, 77 extending perpendicularly from the body of the inserts (two at the bottom and one at the top) and bearing against the edge 49 of the wall passage. The multifunctional insert 7 can thus be an inexpensive component.

[0091] As illustrated in figures 7 and 8, the housing cover 41 includes a rib 41a provided which locks the position of the magnet when the cover is placed in its position.

[0092] The magnet 2 is made of a material known per se and therefore not detailed here. The magnet is prismatic in shape, preferably parallelepiped in general shape. Its dimensions L2 and W2 may be from a few twenty to thirty millimeters. The thickness may be less than 10 millimeters.

[0093] Operation

[0094] Figure 6 illustrates the passage of the oil which is drawn in either by the lift provided by the rotation of the ring or by the operation of the electric oil pump. The oil passage Fl above the magnet has a height E3. The oil passage F2 below the magnet has a maximum height E4 and passes through a path delimited by the walls 45, 46 and 41a.

[0095] The oil passage F3 illustrates the suction provided by the lifting effect of the rotation of the ring 3.

[0096] When the electric oil pump 5 is in operation, the oil level in the first oil reservoir VM drops. The portion of oil delivered to the 4T transmission compartment trickles into the transmission compartment, passes near the magnet (F1,F2) where particles are trapped, then passes through the calibrated hole 8 and returns to the first oil reservoir to be drawn back into the pump.

[0097] In this configuration, it is the first lubrication circuit Cl which prevails, the lifting function may be disprimed, but there is no adverse consequence, the delivery of oil being ensured by the first lubrication circuit Cl which supplies the reservoir chute 9 with oil dispensing and distribution orifices at the appropriate locations.

[0098] When the electric oil pump 5 is not in operation, the oil lifting function is operational, the oil level in the second VT reservoir on the transmission side may drop, but is partially replenished via the calibrated hole 8 from the first VM oil reservoir which is not being drawn by the pump.

[0099] It is therefore understood that the passage provided by the calibrated hole 8 in both directions must be sufficient to ensure the correct operation of the two lubrication configurations described above.

[0100] Furthermore, we have seen that an excessively large cross-section promotes rapid oil transfer under the effect of inertial forces directed along the transverse axis. The cross-section of the calibrated orifice is therefore crucial.

[0101] The configuration shown therefore offers a compromise to ensure proper lubrication operation, whether or not the electric oil pump is operating, and on the other hand to protect these two modes from undesired priming in the event of transverse centrifugal force applied for a certain time.

[0102] The trick of forming the calibrated hole in a small part, i.e. here the multi-function insert 7, allows a late adjustment of the passage section in the development of the electromotor group, after simulations and tests.

[0103] In addition, the proposed multi-function insert allows the magnet to be ideally placed in the oil path in order to maximize the trapping effect.

[0104] This allows for a reasonable quantity of oil and limits the bubbling of the crown in both lubrication configurations. For example, the total quantity of oil can be between 500 ml and 1 liter.

Claims

Demands

1. Motor vehicle power unit comprising an electric machine (1) and a transmission (TR), the transmission comprising at least one differential (DIF) with a ring gear (3) having teeth (31) and providing a lubricating oil lifting function, the power unit comprising a housing (4) separating an electric machine compartment (4M) from a transmission compartment (4T), the electric machine compartment comprising a first oil reservoir (VM) and the transmission compartment comprising a second oil reservoir (VT), the housing having a wall penetration (6), obtained by casting, connecting the second oil reservoir to the first oil reservoir, the power unit comprising: - an oil pump (5), configured to supply a high-pressure lubrication circuit, capable of at least cooling the electric machine and delivering pressurized oil to the transmission elements,- a multi-function insert (7) generally used to seal the wall opening and comprising a calibrated passage hole (8) and receiving elements configured to receive a magnet, the calibrated passage hole defining a predefined passage section between the second oil reservoir and the first oil reservoir, - a magnet (2) housed and held between forms (45) of the housing and the receiving elements (24) of the multi-function insert.

2. Electric motor unit according to claim 1, characterized in that when the electric oil pump is in operation, a first oil circuit (Cl) is established in which the magnet is positioned upstream of the calibrated passage hole (8), and when the electric pump is not in operation and the differential ring is rotating, a second oil circuit (C2) is established in which the magnet is positioned upstream of the lifting zone.

3. Power unit according to any one of claims 1 to 2, wherein the multifunction insert (7) comprises on the one hand an insert body (70) which bears at least in part on the edge of the wall passage and on the other hand one or more retaining elements.

4. Power unit according to claim 3, wherein the retaining elements comprise at least one fixing tab (71) bearing on an edge of the wall passage and / or at least one S-shaped tab (73) bearing on an edge of the wall passage.

5. Power unit according to any one of claims 1 to 4, wherein the multifunction insert (7) is made of plastic material, preferably of polyamide loaded with reinforcing fibers.

6. Electromotor unit according to any one of claims 1 to 5, wherein the calibrated through hole (8) is circular in shape and has a diameter (D8) between 4 mm and 8 mm.

7. Electromotor unit according to any one of claims 1 to 6, further comprising a housing cover (41) and the magnet is further held by at least one rib (41a) formed in the housing cover.

8. An electric motor unit according to any one of claims 1 to 7, wherein the receiving elements are L-shaped, U-shaped, or wedge-shaped walls

9. Electromotor unit according to any one of claims 1 to 8, wherein at least one guide rib (46) is provided at the bottom of the housing, facilitating the installation of the insert.

10. Electric or hybrid vehicle, comprising at least one electric motor unit according to any one of claims 1 to 9.

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