Powertrain equipped with a cooling circuit

Abstract

The invention relates to a powertrain comprising: - at least one electric motor (60), - a speed reducer (10) comprising an outer casing (18), - an electronic control unit (30) which is adapted to control said at least one electric motor and which comprises an outer housing (37), and - a cooling circuit (100) of the electronic control unit. According to the invention, the outer housing bears against the outer casing and the cooling circuit passes through the outer casing. Figure for abstract: Fig.6

Description

Title of the invention: Powertrain equipped with a cooling circuit Technical field of the invention

[0001] The present invention relates generally to the cooling of powertrains.

[0002] It relates more particularly to a powertrain comprising: - at least one electric motor, - a speed reducer comprising an external casing, - an electronic control unit which is adapted to control said at least one electric motor and which comprises an external housing, and - a cooling circuit for the electronic control unit.

[0003] The invention also relates to a motor vehicle equipped with such a powertrain.

[0004] The invention finds a particularly advantageous application in hybrid powertrains comprising two electric motors and an internal combustion engine. State of the art

[0005] The applicant currently markets under the reference “E-Tech” a hybrid powertrain comprising a gearbox which is coupled to two electric motors and an internal combustion engine.

[0006] The electric motors are controlled by means of a control unit which not only transforms the direct current from a storage battery into alternating current but also regulates and distributes this current to the two electric motors.

[0007] Currently, this control unit is fixed on a metal plate which is located high up in relation to the powertrain (this plate having lugs by which it is bolted to a casing of this group). First electrical cables are then provided to connect the accumulator battery to this control unit, and other electrical cables to connect the control unit to the two electric motors.

[0008] Furthermore, a cooling circuit comprising hoses is used to cool the electronic components of this control unit.

[0009] It is understood that when designing the powertrain, care should be taken to find an ideal position for this control unit on the powertrain, so as to minimize the length of the electrical cables and hoses, for reasons of both cost and space.

[0010] But even with this research, the current situation is still not entirely satisfactory. Presentation of the invention

[0011] In order to remedy this, the present invention proposes to integrate the control unit into the powertrain in a different way.

[0012] More particularly, the invention proposes a powertrain as defined in the introduction, in which the external housing of the electronic control module bears against the external casing of the speed reducer and in which the cooling circuit of the electronic control module passes through the external casing of the speed reducer.

[0013] Thus, the invention takes advantage of the contact between the external casing of the speed reducer and the external housing of the electronic control unit to cool the electronic components of the electronic control unit without the need for bulky, fragile and unnecessarily expensive hoses.

[0014] Similarly, this contact can also make it possible to do without electrical cables between the control unit and the electric motor(s). The electrical connection can in fact be ensured by solid conductors (better known as bus bars) integrated into the housings of the powertrain.

[0015] It is therefore understood that the position of the control module on the external casing of the speed reducer facilitates its integration into the powertrain, makes it possible to reduce the size of the latter, to facilitate its assembly and to reduce its cost price.

[0016] Furthermore, this position of the electronic control module on the external casing of the speed reducer makes it possible to stiffen the connection between these two elements and thus reduces the vibrations of the powertrain.

[0017] The invention can also make it possible to share the cooling of the electronic control module with that of at least one other component (the electric motor, the speed reducer, etc.).

[0018] Other advantageous and non-limiting characteristics of the powertrain according to the invention, taken individually or in all technically possible combinations, are the following: - the electronic control unit is connected to the electric motor by current conductors which are integrated at least partly in the external housing; - the external housing comprises, on the one hand, a front wall which is bordered by a side wall and which delimits with the side wall a housing for receiving electronic components, and, on the other hand, an interface wall which closes at least partially said accommodation; - the external casing comprises a bottom wall which is bordered by a side wall and which delimits with the side wall a receptacle, the external housing resting on the external casing (here on the side wall) and closing said receptacle; - said interface wall is solid and hermetically separates said housing from said receptacle; - said interface wall has at least one opening for the passage between said housing and said receptacle of a cooling liquid circulating in the cooling circuit; - a lubricant circulation circuit (also called a lubrication circuit) is provided which passes through the receptacle; - this lubrication circuit is suitable for lubricating the speed reducer; - a second cooling circuit is provided which is adapted to cool said lubricant and which passes through the receptacle; - the cooling circuit has a main chamber located in the outer casing, and coolant inlet ducts into the main chamber and coolant outlet ducts out of the main chamber, at least one of the inlet and outlet ducts passing through the outer casing; - the cooling circuit has a main chamber located in the external casing; - the cooling circuit has an annex part which passes through a casing of the electric motor and which is adapted to cool at least part of said electric motor; - the annex part is located upstream of the part which passes through the external casing, taking into account the direction of circulation of the coolant; - the annex part is located downstream of the part which passes through the external casing, taking into account the direction of circulation of the coolant; - an internal combustion engine is provided which is coupled to said speed reducer.

[0019] The invention also provides a motor vehicle comprising a chassis and a powertrain as defined above.

[0020] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Detailed description of the invention

[0021] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0022] In the attached drawings:

[0023] [Fig-1] is a schematic view of a part of a powertrain according to a first embodiment of the invention;

[0024] [Fig.2] is a view of a first variant embodiment of the powertrain illustrated in [Fig.l];

[0025] [Fig.3] is a view of a second variant embodiment of the powertrain illustrated in [Fig.l];

[0026] [Fig.4] is a schematic view of a second embodiment of the motorcycle group propellant according to the invention;

[0027] [Fig.5] is a view of a first variant embodiment of the powertrain illustrated in [Fig.4];

[0028] [Fig.6] is a view of a second variant embodiment of the powertrain illustrated in [Fig.4].

[0029] In Figures 1 to 6, different embodiments and variants of a powertrain for a motor vehicle are shown.

[0030] In these figures, the powertrain is shown with an orientation which will be that used when it is installed in the motor vehicle and the latter is on a horizontal road.

[0031] In the remainder of the description, the terms “lower” and “upper” will then be used taking into account this orientation, the lower side of an element designating the part of this element which is turned towards the side of the portion of road on which the vehicle is resting and the upper side designating the part of this element which is turned towards the opposite side.

[0032] The vehicle carrying this powertrain could be of any type (car, truck, boat, plane, etc.). Here we will consider that it is a car (a personal or utility vehicle).

[0033] The powertrain could be purely electric, i.e. without an internal combustion engine.

[0034] But we will consider here that it is a hybrid powertrain comprising a battery of accumulators, at least one electric motor and at least one internal combustion engine.

[0035] More specifically, this will involve a hybrid powertrain comprising two electric motors and an internal combustion engine.

[0036] One of the electric motors, the one adapted to deliver the greatest torque, will preferably be an axial flux motor. This electric motor 60, shown in [Fig. 6], comprises a casing 61, as well as a rotor 63 and two stators 62 located on either side of the rotor, these rotors and stators all being housed in the casing 61.

[0037] The other of the electric motors (not shown) is here an alternator-starter of the type HSG.

[0038] The internal combustion engine (not shown) is a spark-ignition engine.

[0039] These three motors are all coupled to the same speed reducer. This reducer is here formed by a gearbox 10 comprising an external casing 18 housing three parallel shafts, including a central shaft 11 coupled to the rotor 63 of the electric motor 60 and two other shafts 12, 13 equipped with pinions meshed with pinions of the central shaft 11. One of these two shafts is coupled to the drive wheels of the motor vehicle.

[0040] The architecture of this gearbox 10, of the “E-tech” type, not being the subject of the present invention and being already known to those skilled in the art, it will not be described here in more detail.

[0041] It will only be noted in the figures that a lower part 19 of the external casing 18 forms a sort of box for the shafts 11, 12, 13 and that another part of the external casing 18 delimits a receptacle 25 which is located outside this box and which opens outwards. This other part is preferably located above the lower part of the external casing 18 and is then called the upper part 20. Alternatively, this other part could be located elsewhere on the external casing 18.

[0042] The upper part 20 of the external casing 18 comprises a bottom wall 21 which is bordered over its entire contour by a side wall 22. The side wall 22 thus rises from the edge of the bottom wall 21 and it delimits with the latter the receptacle 25. The latter is therefore open upwards.

[0043] Preferably, the bottom wall 21 projects on either side of the lower part 19 of the external casing 18.

[0044] Advantageously, the upper edge of the side wall 22 flares and forms a flat peripheral rim 23 (also called a “flange”) which extends all around the side wall 22 (see [Fig.l]).

[0045] The invention then proposes to take advantage of the upper part 20 of the external casing 18 to fix an electronic control module 30 there.

[0046] This electronic control module 30 is designed to control at least one of the electric motors (here both).

[0047] This electronic control module 30 comprises for this purpose an external housing 37 which houses electronic components forming an inverter 31, a power stage 32, and a voltage regulator 33.

[0048] The outer casing 37 has a shape similar to that of the upper part 20 of the outer casing 18 and is turned over thereon. More precisely, it comprises a front wall 38 bordered over its entire contour by a side wall 39 which flares and forms a flat peripheral rim 39A (also called a “flange”).

[0049] The front wall 38 of the external housing 37 delimits with the side wall 39 a housing 35 for the electronic components.

[0050] The peripheral rim 39A has dimensions similar to those of the peripheral rim 23 of the upper part 20 of the external casing 18 of the gearbox 10, so that these two rims can overlap (see [Fig.l]). It is intended to fix them in this position by any fixing means, for example by means of bolts engaged through openings provided in these rims and regularly distributed along these rims.

[0051] It will be noted here that the electronic power module 30 may be assembled in a location remote from the powertrain assembly plant, so as to form a single-piece assembly that is easy to install on the rest of the powertrain. To protect the electronic components during its transport to the powertrain assembly plant, the housing 37 preferably comprises an interface wall 40 which at least partially closes the housing 35.

[0052] The external casing 18 is preferably made of aluminum alloy.

[0053] The external housing 37 of the electronic control module 30 can also be made of the same material, or of a different material (stamped sheet metal, etc.). In any case, it is made of a material with little elasticity so as to be rigid.

[0054] If the external housing 37 is rigid, the interface wall 40 can be either rigid or flexible. Here, it is made of the same material as the external housing 37.

[0055] This interface wall 40 has a plate shape whose edge overlaps that of the peripheral rim 39A of the housing 37. Its edge is therefore designed to be pinched between the two peripheral rims 23, 39A.

[0056] This interface wall 40 can have a sealing function, and in all cases it has a function of protecting the electronic components against dust and other dirt.

[0057] The powertrain also comprises a cooling circuit 100 for the electronic control module 30.

[0058] In operation, the electronic components of this electronic control module 30 in fact emit significant heat which must be evacuated, here by means of a cooling liquid circulating in this cooling circuit 100.

[0059] According to the invention, this cooling circuit 100 passes through the external casing 18 of the gearbox 10. More precisely, it passes into the upper part 20 of this casing, through the receptacle 25.

[0060] This cooling circuit 100 is designed to circulate the coolant in or against the electronic control module 30. For this purpose, it comprises a pump (not shown) for forcing the coolant to circulate, as well as various pipes, part of which is shown in the various figures.

[0061] In Figures 1 to 3 on the one hand, and 4 to 6 on the other hand, two main embodiments of the powertrain are shown, one in which the cooling circuit 100 enters the housing 35 delimited by the external casing 37 of the electronic control module 30, and the other in which the cooling circuit 100 remains mainly confined in the receptacle 25.

[0062] In [Fig. 1], the first embodiment of this power unit is shown in detail.

[0063] In this embodiment, the housing 35 delimited by the external housing 37 of the electronic control module 30 forms a main chamber 110 inside the external housing 37 of the electronic control module 30. This main chamber 110 is confined in this housing and extends between the electronic components and the interface wall 40.

[0064] The cooling circuit 100 then comprises a coolant inlet pipe in the main chamber 110, called the inlet pipe 111, and a coolant discharge pipe from the main chamber 110, called the outlet pipe 112.

[0065] These two inlet 111 and outlet 112 pipes are formed from the same material as the outer casing 18 of the gearbox 10. They are formed in one piece with it. They each have a lower end located outside the outer casing 18, by which they can be connected to the rest of the cooling circuit 100. These two lower ends are located on either side of the lower part 19 of the outer casing 18. They extend vertically, in parallel with each other, pass through the bottom wall 21 of the receptacle 25 and extend up to the height of the peripheral rim 23 of the outer casing 18. They thus open out at the height of the interface wall 40.

[0066] In this first embodiment, this interface wall 40 then has two openings so as not to hinder the circulation of the cooling liquid. This wall is however called “full”, in the sense that it does not have other openings and that it thus prevents the cooling circuit from exiting the main chamber 110 other than via the outlet duct 112.

[0067] Here, the receptacle 25 is therefore crossed by the two inlet 111 and outlet 112 pipes and it is otherwise left empty.

[0068] In [Fig.2], a first variant embodiment of the powertrain illustrated in [Fig.l] is shown.

[0069] This variant is essentially distinguished from the solution illustrated in [Fig.l] in that the remainder of the receptacle 25 is not left empty. On the contrary, it is used to ensure the circulation of a lubricant from one side of the gearbox to the other, which avoids using a hose to fulfill this function.

[0070] The powertrain in fact conventionally comprises a lubrication circuit 200 making it possible to supply a lubricant to different zones of the powertrain, in particular in the gearbox 10.

[0071] Here, this lubrication circuit 200 comprises a main chamber 201 formed by the receptacle 25. It also comprises inlet ducts 202 and outlet ducts 203 for the lubricant, which here have the shape of tubes bordering two openings provided in the upper part 20 of the external casing 18. Here, these two openings are provided in the bottom wall 21 of this upper part 20 of the external casing 18, on either side of the lower part 19 of this casing.

[0072] In this variant, the inlet ducts 111 and outlet ducts 112 of the cooling circuit 100 are therefore immersed in the lubricant.

[0073] Here, the coolant and lubricant inlet pipes may be located on the same side of the external casing 18 or on either side of this casing. In other words, the coolant and lubricant flows may circulate in the same direction, as shown in [Fig.2], or in the opposite direction.

[0074] In [Fig.3], a second variant embodiment of the powertrain illustrated in [Fig.l] is shown.

[0075] This variant is essentially distinguished from the solution illustrated in [Fig.2] in that the container 25 is also crossed by a secondary cooling circuit 155.

[0076] The lubricant heats up naturally when it lubricates hot mechanical parts, in particular gearbox pinions. It is therefore necessary to cool it so that its temperature does not rise above a threshold beyond which its lubricating properties would be degraded. Furthermore, it may be necessary to heat this lubricant when starting the powertrain.

[0077] For at least one of these two reasons, it is proposed to place this secondary cooling circuit 155 in the container 25 so that it is immersed in the lubricant and the upper part 20 of the external casing 18 forms a heat exchanger.

[0078] This secondary cooling circuit 155 comprises a main heat exchange chamber 156 which is entirely immersed in the lubricant in the sense that it is not in contact with either the external casing 18 or the interface wall 40.

[0079] This main heat exchange chamber 156 opens to the outside of the external casing 18 via inlet 157 and outlet 158 ​​pipes for cooling liquid, which here again have the shape of tubes bordering two openings provided in the bottom wall 21.

[0080] The cooling circuit 100 and the secondary cooling circuit 155 are here distinct, which allows the liquids which circulate therein to have temperatures different. Typically, the liquid circulating in the secondary cooling circuit 155 may have a temperature higher than that of the liquid circulating in the cooling circuit 100. Common circuits could of course be used, but this would require significantly lowering the temperature of the entire cooling liquid, which would be to the detriment of the overall efficiency of the powertrain.

[0081] Here, the inlet pipes 157 of the secondary cooling circuit 155 and of the lubrication circuit 200 are located opposite each other with respect to the lower part 19 of the external casing 18. In other words, the flows of coolant and lubricant circulate in opposite directions to optimize heat exchanges.

[0082] Finally, it can be noted that this variant illustrated in [Fig. 3] also differs from the solution illustrated in [Fig. 2] in that the lubrication circuit 200 does not include an outlet pipe. On the contrary, an opening 205 is provided in the bottom wall 21 of the receptacle 25 so that the lubricant can flow by gravity towards the lower part 19 of the external casing 18 of the gearbox 10.

[0083] In [Fig. 4], a second embodiment of the powertrain is shown which differs mainly from the first in that the main chamber 120 of the cooling circuit 100 is confined not in the external housing 37 of the electronic control module 30, but in the receptacle 25, between the interface wall 40 and the bottom wall 21 of this receptacle 25.

[0084] In this embodiment, the external housing 37 preferably has a reduced height compared to that which it has in the first embodiment, so that the electronic components are located at a zero or reduced distance from the interface wall 40 to optimize heat exchanges.

[0085] This time, the inlet 121 and outlet 122 pipes have tube shapes which border two openings provided in the bottom wall 21, on either side of the lower part 19 of the external casing 18. These tubes extend from the lower side of this bottom wall 21 and therefore make it possible to connect the main chamber 120 with the rest of the cooling circuit 100.

[0086] As illustrated in [Fig.4], the interface wall 40 is not pierced with an opening. On the contrary, it is solid so as to prevent the cooling liquid from being able to penetrate into the external housing 37 of the electronic control module 30.

[0087] Thus, the electronic control module 30, which is assembled in a location remote from the powertrain assembly plant, is well protected since its electronic components are confined in the external housing 37, behind the interface wall 40, and do not risk any degradation or soiling during transport.

[0088] This solution also has the advantage of limiting the size of the cooling circuit 100.

[0089] In [Fig.5], a first variant embodiment of the powertrain illustrated in [Fig.4] is shown, which is distinguished by its interface wall 43.

[0090] This interface wall 43 in fact has at least one opening allowing the cooling liquid to circulate from the receptacle 25 to the chamber 35 delimited by the external housing 37 of the electronic power module 30. In practice, it has a number of openings greater than or equal to three, to promote the circulation of the cooling liquid around the electronic components.

[0091] In this variant, the electronic components must of course be housed in waterproof boxes or be waterproof themselves.

[0092] They are thus better cooled than in the solution illustrated in [Fig.4], but are less well protected during transport of the power electronic module 30.

[0093] In [Fig.6], a second variant embodiment of the power unit illustrated in [Fig.4] is shown.

[0094] It is distinguished by its inlet pipe 121 for coolant in the receptacle 25 which is connected to the casing 61 of the electric motor 60. This connection is made without a flexible hose. It is therefore the casings of the gearbox 10 and the electric motor 60 which are shaped to communicate through this inlet pipe 121. These casings can therefore be formed from a single piece or be assembled using a simple sealing joint.

[0095] Thus, the cooling circuit 100 is used to cool not only the electronic control module 30 but also the electric motor 60 (and in particular its stators 62).

[0096] In [Fig.6], the coolant therefore begins by cooling the electric motor 60 before cooling the electronic control module 30.

[0097] Of course, as a variant, the liquid could circulate in the opposite direction in order to start by cooling the electronic control module 30 before cooling the electric motor 60.

[0098] As shown in [Fig.6], the interface wall 40 is solid but it could also have liquid passage openings, as in the variant illustrated in [Fig.5].

[0099] In all these embodiments and variants, the electronic control module 30 can be connected to the storage battery and to the electric motors by flexible electric cables.

[0100] However, preferably, at least one of these electrical cables will be replaced over at least part of its length by rigid electrical conductors of the bus bar type, embedded in the external casing 18 of the gearbox. 10 or attached to it.

[0101] Thus, in the variant illustrated in [Fig.6], it could be provided to electrically connect the electronic components of the electronic control module 30 to the electric motor 60 by bus bars embedded in the walls (or fixed to the walls) of the external housing 37 of the electronic control module 30, of the external casing 18 of the gearbox 10, and of the casing 61 of the electric motor 60.

[0102] The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to provide any variant in accordance with the invention.

Claims

Claims

1. Power unit comprising: - at least one electric motor (60), - a speed reducer (10) comprising an external casing (18), - an electronic control unit (30) which is adapted to control said at least one electric motor (60) and which comprises an external housing (37), and - a cooling circuit (100) of the electronic control unit (30), characterized in that the external housing (37) bears against the external casing (18) and in that the cooling circuit (100) passes through the external casing (18).

2. Powertrain according to claim 1, wherein the electronic control unit (30) is connected to the electric motor (60) by current conductors which are integrated at least partly in the outer casing (18).

3. Powertrain according to claim 1 or 2, in which the external housing (37) comprises, on the one hand, a front wall (38) which is bordered by a side wall (39) and which delimits with the side wall (39) a housing (35) for receiving electronic components (31, 32, 33), and, on the other hand, an interface wall (40; 43) which at least partially closes said housing (35).

4. Powertrain according to one of claims 1 to 3, in which the external casing (18) comprises a bottom wall (21) which is bordered by a side wall (22) and which delimits with the side wall (22) a receptacle (25), the external housing (37) resting on the side wall (22) and closing said receptacle (25).

5. A powertrain according to claims 3 and 4, wherein said interface wall (40) is solid and hermetically separates said housing (35) from said receptacle (25).

6. Powertrain according to claims 3 and 4, wherein said interface wall (43) has at least one opening for the passage between said housing (35) and said receptacle (25) of a coolant circulating in the cooling circuit (100).

7. Powertrain according to one of claims 4 to 6, in which a circulation circuit (200) of a lubricant is provided which passes through the receptacle (25).

8. A powertrain according to claim 7, wherein there is provided a second cooling circuit (155) which is adapted to cool said lubricant and which passes through the receptacle (25).

9. Powertrain according to one of claims 1 to 8, in which the cooling circuit (100) has a main chamber (110) located in the external housing (37), and inlet conduits (111) for coolant in the main chamber (110) and outlet conduits (112) for coolant out of the main chamber (110), at least one of the inlet conduits (111) and outlet conduits (112) passing through the external casing (18).

10. Powertrain according to one of claims 1 to 8, in which the cooling circuit (100) has a main chamber (120) located in the external casing (18).

11. Powertrain according to one of claims 1 to 10, in which the cooling circuit (100) has an ancillary part (164) which passes through a casing of the electric motor (60) and which is adapted to cool at least part of said electric motor (60).

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