ELECTROMOTIVE GROUP WITH MOUNTING OF A VOLTAGE CONVERTER

Abstract

The invention relates to an electromotive group for an electrically driven motor vehicle, extending in a reference frame comprising a first direction, a second vertical direction, and a third direction, the electromotive group comprising an electric machine, a transmission engaged with the machine rotor and with the wheel shafts, a casing housing the electric machine and the transmission, a voltage converter housed in a housing (3) fixed to the casing in a lower zone of the electromotive group, the fixing of the casing comprising a stud (4) fixed to the casing, with an axis parallel to the first direction, the casing comprising a housing capable of receiving the stud, and a nut (44) screwed onto the stud, the casing further comprising two ears (36, 37) in which two respective fixing screws are inserted and screwed onto the casing along the third direction. Figure 2

Description

Title of the invention: ELECTROMOTIVE GROUP WITH MOUNTING OF A VOLTAGE CONVERTER

[0001] The invention relates to a solution for positioning and fixing a voltage converter on an electric vehicle electromotor group, in other words the mounting of a voltage converter on an electromotor group.

[0002] In the configuration of an electric vehicle equipped with an electromotive group of interest, such a voltage converter is located in a lower zone of the electromotive group.

[0003] We are interested here in zero-emission vehicles with electric traction, namely 100% electric vehicles. We are interested here in private vehicles where the integration constraints of the various components are multiple in a limited and very constrained allocated geometric volume. Indeed, vehicle designers want to maximize the volume made available for occupants and for storage.

[0004] Furthermore, on these particular vehicles, the power steering is of the electric type and requires a sufficiently powerful electrical power supply. The voltage converter of interest here has the function in particular of supplying the electric power steering, located near the converter, from the main battery of the vehicle (the traction battery).

[0005] Regarding the mounting of the voltage converter, access to the fixing elements of the voltage converter must be provided on the one hand on the assembly table in the vehicle assembly plant and on the other hand for a possible after-sales maintenance operation, for example the removal and reinstallation of the voltage converter.

[0006] It is thus necessary to leave the passage for a screw socket opposite each fixing screw for the case of the vehicle assembly plant, and it is also necessary to leave the passage for a key available in a general mechanics garage in order to be able to remove the screws and to be able to reinstall them after intervention.

[0007] Furthermore, preference is given to isostatic mounting types, i.e. three-point mounting, which allows for balanced and reliable fixing over time without generating residual stresses on the part to be fixed. In addition, any source of noise must be avoided as much as possible, which can be generated by vibratory stresses when the vehicle is running, on different road surfaces and surfaces.

[0008] In the assembly of the known voltage converter, the three screw fixings are parallel to each other, which allows screwing in a single operation with three parallel rotating bushings in the assembly plant.

[0009] However, it turns out that the known configuration (with three parallel screws) is not ideal for overall optimization from the integration point of view, in particular for the management of electrical cables which have a route close to the passage of the screw sockets, the cables risking being damaged in contact with the screw sockets.

[0010] Furthermore, since the voltage converter is positioned from below, it would be preferable to have a pre-positioning before inserting and screwing the 3 fixing screws.

[0011] On the other hand, in after-sales maintenance, visibility and accessibility are not ideal.

[0012] The inventors therefore sought to improve the solution identified above.

[0013] To this end, the present invention proposes an electromotive group configured to supply torque to wheels of an electrically driven motor vehicle, the electromotive group extending in an orthogonal reference frame comprising a first direction, a second direction, and a third direction, the second direction being oriented vertically, thus defining a lower zone and an upper zone of the electromotive group, the electromotive group comprising: - at least one electrical machine, having a rotor rotating around an axis parallel to the first direction, - a transmission, engaged with the rotor and configured to be engaged with two respective wheel shafts, - a casing housing at least the electric machine and the transmission, - a voltage converter housed in a housing fixed to the casing in the lower zone of the electromotive group, by means of fixing elements, characterized in that the fixing elements comprise: - a stud fixed to the casing, with an axis parallel to the first direction, the housing comprising a first projection with a housing capable of receiving the stud, and a nut screwed onto the stud, - the housing comprising first and second ears in which respective first and second fixing screws are inserted and screwed into first and second holes of the casing along respective axes parallel to the third direction.

[0014] Thanks to the provisions promoted above, it is possible to improve the assembly process in the assembly plant.

[0015] The proposed solution allows pre-positioning before insertion and screwing of two fixing screws.

[0016] In addition, access and visibility in after-sales situations, particularly in maintenance garages, are improved, or at least not degraded.

[0017] It is noted that the housing housing the voltage converter is obtained by molding from a plastic material, which makes it possible to provide complex and multiple shapes resulting from the molding forming the majority of the fixing elements.

[0018] It should be noted that what is called here 'wheel shaft' covers any lateral transmission connection between the gearbox output and the wheel, eg any transmission connection with constant velocity joints.

[0019] It is noted that the first projection is a cantilevered arm, extending from the main body of the housing. Such a cantilevered arm provides flexibility in the first direction and the second direction, the position of the housing provided to receive the stud consequently benefits from this flexibility and this allows a catch of the chain of ribs and a swallow effect during the insertion movement.

[0020] According to one embodiment, the casing comprises a rib forming a stop for insertion of the housing along the third direction and the housing comprises a concave housing for receiving and framing said rib. Whereby, the translational movement along the third direction is guided and stopped by the cooperation between said stop-forming rib and the aforementioned concave housing. This stop system provides mechanical protection for the first projection in the event of an excessively violent insertion movement. It is the stop-forming rib which will take up the main force and the first projection will not be damaged.

[0021] According to one embodiment, the housing comprises at least one guide notch or a guide groove for guiding electrical cables.

[0022] The converter housing is equipped with receiving shapes to ensure the guidance of the electrical cables and prevent them from moving during vibration stresses or impacts suffered by the vehicle. The presence of these shapes directly on the housing makes it possible to avoid installing specific guide lugs.

[0023] According to one embodiment, the housing is fixed to the casing in a lower and rear zone of the electromotor group, a lower and front zone of the electromotor group being occupied by an air conditioning compressor forming part of the electromotor group. The lower zone of the electromotor group houses both the air conditioning function and the power converter function, in particular for the power steering.

[0024] According to one embodiment, the first and second ears are arranged on either side of a housing body, along the first direction. The fixing thus produced is solid and the forces are well balanced.

[0025] According to one embodiment, the casing is made of a metal alloy based on aluminum or magnesium. Aluminum casting is a relatively affordable process. Such a material is lightweight and, in addition, ribs can be formed in the casting. Machining rework requires standard tools that have a long service life.

[0026] According to one embodiment, the housing is made of plastic material, based on a polymer chosen from polyethylenes, polypropylenes, polyamides and polyesters. Advantageously, complex shapes resulting from the molding of the plastic material can be provided, in particular the cable guide tabs and the fixing ears, as well as the concave housing capable of receiving the stud. Other polymer variants can also be considered.

[0027] According to one embodiment, the lower wall of the housing is lined with a protective screen, acting as mechanical protection. This makes it possible to protect the voltage converter against stone projections which may occur during driving and which may affect the underbody of the vehicle, including the compartment of the electric motor unit. The voltage converter is thus protected even in the absence of an underbody screen.

[0028] According to one embodiment, the casing comprises two additional ribs capable of framing, along the first direction, a second projection projecting from the housing, to participate in pre-positioning along the first direction.

[0029] According to one embodiment, the housing has a generally parallelepiped shape, with two cut sides arranged on the front side of the housing according to the mounting direction. This improves the overall compactness and integration.

[0030] The cut sides can be symmetrical or asymmetrical.

[0031] The front shape of the housing including said cut sides as well as the aforementioned guide groove make it possible to provide a passage, immobilization and protection function for two or three electric cables.

[0032] The invention also relates to an electric motor vehicle comprising a cradle and an electromotive group as described previously, mounted above the cradle along the second vertically oriented direction, the first direction corresponding to a transverse axis of the vehicle, the second direction corresponding to a vertical axis relative to the local ground, and the third direction corresponding to a longitudinal axis of the vehicle.

[0033] The invention also relates to an electric motor vehicle as described above, and comprising a front axle with steered wheels, an electric power steering configured to steer wheels of the front axle, the electric power steering being electrically powered by the voltage converter of the electromotive group.

[0034] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: [Fig.l] is a schematic representation of a side view of an example of voltage converter housed in a converter housing according to an embodiment of the present invention; [Fig.2] represents the converter housing of [Fig.l] seen from the front; [Fig.3] represents the converter housing of [Fig.l] in a perspective view; [Fig.4] shows schematically in perspective view a partial view of an electromotive group on which is mounted, in the lower zone, the voltage converter of [Fig.l]; [Fig.5] shows schematically, in front view from the rear, a partial view of an electromotive group on which the voltage converter of [Fig.l] is mounted with in addition the assembly preparation table used in the assembly plant; [Fig.6] shows schematically in side view the electromotor group mounted on the preparation table, on which is mounted the voltage converter of [Fig.l], with in addition a detail view centered on the stud located in front of the housing; [Fig.7] schematically shows an electric vehicle with an electromotor group driving the front axle [Fig.8] illustrates in more detail the first projection projecting from the body of the case.

[0035] We are interested here in an electric motor vehicle, such as that illustrated in [Fig.7], namely a vehicle equipped with an electric drive train powered from a battery 71.

[0036] More specifically, the vehicle comprises a front axle driven by an electric machine. The electric machine drives the front wheels via a transmission, most often equipped with a differential, and via axle shafts.

[0037] Furthermore, in the example illustrated, the front wheels are steered, that is to say they are mounted on steering knuckles which can be steered along a substantially vertical axis as known per se. The steering system is assisted, based on electrical energy, the assistance member being an electric motor marked 75. It is therefore an electric power steering system.

[0038] The electric assistance motor 75 is in the illustrated example installed on the steering rack system as known per se, but alternatively the electric assistance motor could be installed on the steering column.

[0039] The electric power steering is electrically powered by a voltage converter marked 30 which takes as input the voltage of the traction battery 71, higher than the operating voltage used for the power steering system, and delivers as output a voltage of type 12 volts or 24 volts usable by the power steering system. The voltage converter 30 comprises electrical and electronic circuits housed in a housing 3.

[0040] The electric machine 1 is part of an assembly called here an 'electric motor group' referenced 10. Said electric motor group 10 comprises, in addition to the electric machine: the transmission 8, and accessories such as for example an air conditioning compressor 9 and in our case the voltage converter 30 used for the electric power steering system.

[0041] The electromotive group 10 comprises a casing 2, said casing housing at least the electric machine and the transmission 8. In other words, the stator of the electric machine is fixed inside this casing, as well as bearings supporting the rotor. The rotor of the electric machine rotates around an axis Y0 parallel to the transverse axis Y of the vehicle.

[0042] In the example illustrated, all or part of the transmission components are also mounted in the casing 2.

[0043] The transmission 8 comprises in the illustrated example a reducer and a differential. As visible in [Fig.6], the outputs of the differential extend along the axis Y8 parallel to the transverse axis of the vehicle and parallel to the first direction Y as defined in this document.

[0044] The casing 2 is made of a metal alloy based on aluminum or magnesium. The metal alloy part from the foundry is then reworked in machining, in particular to drill holes, make tappings and counterbores, which will be discussed later.

[0045] The casing 2 can be obtained in a single piece or in two pieces assembled together.

[0046] To fix the housing 3 of the voltage converter relative to the casing 2, several fixing elements are used which will be detailed below.

[0047] We are talking here about isostatic mounting type mounting, i.e. generally three-point. The fixing in question here is used to hold the modestly sized part under its own weight, and subjecting it, if necessary, to vibratory stresses and shocks when the vehicle is moving.

[0048] Thus, various shapes are provided in the casing 2 to accommodate the mounting of the housing 3 of the voltage converter 30 discussed below.

[0049] The housing 3 comprises a main body 90 and auxiliary shaped elements serving in particular for fixing the housing to the casing as well as for its prior prepositioning.

[0050] The auxiliary shaped elements also serve incidentally to ensure the guidance of electrical cable(s) which pass in the vicinity of the housing.

[0051] The body 90 of the housing 3 comprises a lower face 91, an upper face 92, a left side face 93, a right side face 94, a front face 96 and a rear face 95.

[0052] The body 90 of the housing 3 is generally parallelepipedal.

[0053] It should be noted that the terms front and rear as well as left and right are conventionally taken according to the orientation of the vehicle in which the housing is placed. The front direction is illustrated by an arrow marked AV in Figures 1, 3, 4, 6, 7 and 8.

[0054] The movement of insertion of the housing into the electromotor group is from back to front, the front face 96 is housed in an available space.

[0055] Cut sides 67, 68 are provided in the vicinity of the front face 96, on either side of the top of the front portion.

[0056] The cut sides 67, 68 accommodate the passage of one or more cables marked 69 and illustrated in figures 2 and 4.

[0057] The housing comprises a first projection 31 with a housing 32 capable of receiving a stud, or more generally any current section of rod extending transversely to the insertion movement.

[0058] The first projection is a cantilever arm, extending from the main body of the housing in the third direction X forward.

[0059] In an illustrated example, visible in [Fig. 3], a lower reinforcing rib 88 is provided to support the first projection and increase the robustness of the first projection 31. The lower reinforcing rib 88 is arranged continuously under the first projection 31 and extends vertically over a large part of the height LZ of the housing.

[0060] Due to its cantilevered structure, the first projection 31 offers flexibility in the first direction and in the second direction, thus allowing certain tolerances and dispersions of mass production to be taken into account.

[0061] The housing comprises a left ear 37 and a right ear 36. Each ear is pierced with an orifice 38 intended to receive a fixing screw.

[0062] Opposite the orifice of the left ear is a tapped blind hole 28 with axis XI into which a first fixing screw 81 is screwed. Similarly, opposite the orifice of the right ear is another tapped blind hole 28 with axis X2 into which a second fixing screw 82 is screwed.

[0063] Advantageously, the first and second fixing screws 81, 82 each comprise an integrated washer. This integrated washer bears on a counterbore made during machining on the casing so as to lie flat and provide reliable and robust fixing.

[0064] The axes XI,X2 as well as the first and second ears are arranged on either side on the other side of a box body, along the first direction Y. The axes XI,X2 are spaced apart by a distance slightly greater than the length of the box LY.

[0065] The casing 2 comprises a rib 22 forming a stop for inserting the housing along the third direction X, and the plastic housing a concave housing 33 for receiving and frame rib 22.

[0066] Considering the profile of the upper fixing elements of the housing, the concave housing 33 is interposed between a lower peak 35 which forms in the example illustrated the top of the groove 34 for the cables, and the second projection 39 which forms the upper peak.

[0067] The casing 2 comprises two additional ribs, 25, 26 arranged vertically or obliquely but with a vertical component

[0068] The two additional ribs frame a second projection 39 which extends forwardly from the housing, the second projection forming a horizontal tongue, which may have entry chamfers.

[0069] The dimensions of the LX LY LZ housing according to the three dimensions are between 30 mm and 100 mm. But we note that the principle of mounting and fixing is applicable to any dimension.

[0070] The stud 4 is fixed in a tapped hole 21 on a finger or projection 24 provided on the casing 2. From the body of the casing 2, the projection 24 projects downwards (Z-).

[0071] In the example illustrated, the stud 4 comprises a first threaded portion 42 which is screwed into the tapped hole of the casing, a collar 41 which has the function of stopping the screwing of the first threaded portion. The stud 4 comprises a second threaded portion 43 received in the housing 32 of the aforementioned plastic case.

[0072] As the housing is in the shape of an open C, it is not necessary to thread the housing from the end of the second threaded portion. The first projection 31 with its housing 32 is housed around the second threaded portion 43 according to a simple translational movement in the third direction X.

[0073] A nut 44 is screwed onto the second threaded portion 43 to tighten the first projection 31 against the collar 41 of the stud 4.

[0074] Access to this nut can be direct along Yl. In a variant as illustrated, the casing 2 comprises a casing web 48 which extends in the XZ plane and forms a reinforcement of the portion of the casing which houses the transmission components. Provision is made in this casing web to have a wide orifice 47 opposite the stud, centered on the Yl axis, as illustrated in [Fig.6] in the zoomed part, to leave a wide passage for a screwing / unscrewing socket and for a socket wrench.

[0075] For the situation in an after-sales maintenance garage, access to nut 44 for its unscrewing is possible from below the electromotor group with a conventional key.

[0076] Turning to [Fig.8], it can be provided that the housing 32 capable of receiving the stud 4 is an oblong shape to tolerate a certain dispersion of positioning according to the third direction X. The final position according to the third X direction is obtained by screwing in the fixing screws 81, 82.

[0077] Furthermore, two branches 32a, 32b may be provided which move away from each other by widening and form a guide to facilitate the insertion movement even if the housing is not completely opposite the stud.

[0078] In the vehicle assembly plant, the electromotive group is installed on an assembly preparation table marked 100. This assembly table 100 is a tool which facilitates the assembly operations; the electromotive group is mounted there, as well as a certain number of accessories which are fixed there, or others which are temporarily placed in indexers, including in particular the power steering components.

[0079] It is noted that when the electromotive group is installed on the assembly table, access to the face of the nut 44 as well as to the face of the first and second fixing screws 81, 82 remains easy. This is illustrated in Figures 5 and 6.

[0080] After preparing the electromotor group and all its accessories, the table 100 equipped with the electromotor group 10 is assembled to the chassis of the vehicle.

[0081] Furthermore, there is provided in the vehicle 7, a front cradle marked 5 and visible in [Fig.4], on which rests all or part of the electromotive group. As known per se, the cradle is presented as a mechanically welded structure with side members and cross members.

[0082] It is noted that the presence of the front cradle does not prevent access in the after-sales network to the two fixing screws 81, 82 as well as to the nut 44 screwed onto the stud.

[0083] According to an optional arrangement, it is provided to add under the lower face of the housing a protective screen 55, acting as mechanical protection. This protective screen 55 makes it possible to protect the voltage converter against projections of stones which may occur during driving and which may affect the underbody of the vehicle including the compartment of the electromotive group.

Claims

Claims

1. An electromotive group configured to provide torque to the wheels of an electrically powered motor vehicle, the electromotive group extending in an orthogonal reference frame comprising a first direction (Y), a second direction (Z), and a third direction (X), the second direction (Z) being oriented vertically, thus defining a lower zone and an upper zone of the electromotive group, the electromotive group comprising: - at least one electric machine (1), having a rotor rotating about an axis (Y0) parallel to the first direction (Y), - a transmission (8), engaged with the rotor and configured to be engaged with two respective wheel shafts, - a casing (2) housing at least the electric machine and the transmission, - a voltage converter (30) housed in a housing (3) fixed to the casing in a lower zone of the electromotive group, by means of fixing elements,characterized in that the fixing elements comprise: - a stud (4) fixed on the casing, with an axis (Yl) parallel to the first direction, the housing comprising a first projection (31) with a housing capable of receiving the stud, and a nut (44) screwed onto the stud, - the housing comprising first and second ears (36,37) in which respective first and second fixing screws (81,82) are inserted and screwed into first and second orifices (28) of the casing along respective axes (XI,X2) parallel to the third direction (X).,

2. An electromotive group according to claim 1, characterized in that the casing comprises a rib (22) forming a stop for inserting the housing along the third direction, and the housing comprises a concave housing (33) for receiving and framing the rib.

3. Electromotive group according to any one of claims 1 to 2, characterized in that the housing comprises at least one guide notch or guide groove (34) for guiding electric cables.

4. Electromotive group according to any one of claims 1 to 3, characterized in that the housing (3) is fixed to the casing in an in- lower and rear of the electromotive group, a lower and front area of ​​the electromotive group being occupied by an air conditioning compressor (9) forming part of the electromotive group.

5. Electromotive group according to any one of claims 1 to 4, characterized in that the first and second ears are arranged on either side of a housing body, along the first direction (Y).

6. Electromotive group according to any one of claims 1 to 5, characterized in that the casing (2) is made of a metal alloy based on aluminum or magnesium.

7. Electromotive group according to claim 2, characterized in that the casing comprises two additional ribs (26, 25) capable of framing, along the first direction (Y), a second projection (39) projecting from the housing, to participate in a prepositioning along the first direction.

8. Electromotive group according to any one of claims 1 to 7, characterized in that the housing has a generally parallelepiped shape, with two cut sides arranged on the front side of the housing in the direction of assembly.

9. Electric motor vehicle comprising a cradle (5) and an electromotive group according to one of claims 1 to 8 mounted above the cradle along the second direction (Z) oriented vertically, the first direction (Y) corresponding to a transverse axis of the vehicle, the second direction (Z) corresponding to a vertical axis relative to the local ground, and the third direction (X) corresponding to a longitudinal axis of the vehicle.

10. Electric motor vehicle according to claim 9, comprising a front axle with steered wheels, an electric power steering configured to steer the steered wheels of the front axle, the electric power steering being electrically powered by the voltage converter (30) of the electromotive group.

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