Reduction gear of hybrid power assembly

Abstract

The invention relates to a reduction gear comprising a housing (100) housing a shaft and a pinion of a gearbox and comprising a cooling and lubricating circuit adapted to spray a lubricating liquid onto the shaft and the pinion. According to the invention, the reduction gear further comprises an electric motor (200) comprising an output shaft (201) adapted to be coupled to one of the aforementioned shafts and cooled and lubricated by a pump mechanically driven by the electric motor using said lubricating liquid.

Description

Technical Field

[0001] The present invention generally relates to hybrid powertrains.

[0002] The invention more particularly relates to a reducer, typically a gearbox, comprising a housing housing at least one shaft and at least one pinion and comprising a cooling and lubricating circuit suitable for spraying lubricating fluid onto the aforementioned shaft and pinion.

[0003] The invention also relates to a motor vehicle comprising a powertrain including an internal combustion engine and a reduction gear. Background Art

[0004] In order to move forward, the motor vehicle is equipped with a powertrain. The powertrain can have a variety of structures.

[0005] For example, the powertrain may include an internal combustion engine, a clutch, a transmission, and a differential that distributes the transmission's torque to the vehicle's two drive wheels. A water cooling system includes a main heat exchanger ("radiator") located at the front of the vehicle and cools the internal combustion engine to prevent it from overheating.

[0006] Today, these powertrains are increasingly equipped with electric motors in order to protect the environment. In motor mode, such an electric motor helps the internal combustion engine to propel the motor vehicle or even replaces it in certain operating phases; in generator mode, the electric motor recovers mechanical energy and converts it into electrical energy for storage in the battery.

[0007] The electric motor is then usually placed close to the internal combustion engine or the radiator so that it can be cooled using a water circuit.

[0008] The main disadvantage of this solution is that it is both cumbersome and restrictive, since the electric motor must be located in the path of the water circuit and the water circuit must be sized to effectively cool not only the internal combustion engine but also the electric motor, regardless of its rotational speed. Summary of the invention

[0009] In order to overcome the above-mentioned shortcomings of the prior art, the present invention proposes to incorporate the electric motor and its cooling and lubrication system into the gearbox.

[0010] More specifically, according to the invention, a reducer as defined in the introduction is proposed, wherein there is also provided:

[0011] - an electric motor comprising an output shaft coupled to at least one shaft of a reducer, and

[0012] - A pump driven by the electric motor and adapted to use the lubricating fluid for cooling and lubricating the electric motor.

[0013] Thanks to the invention, the components of the reducer and the electric motor are lubricated and cooled by the same volume of lubricant, which reduces the overall size of the assembly.

[0014] Furthermore, thanks to the invention, lubrication and cooling of the motor is provided by the motor driving the pump. This makes it possible to adjust the fluid flow rate according to the speed of the motor to ensure that proper lubrication and cooling are always maintained, neither too low nor too high (which would unnecessarily reduce efficiency).

[0015] This advantage is particularly evident when the motor vehicle is stationary and the electric motor is started. In this configuration, the electric motor can be lubricated and cooled even when the internal combustion engine remains stationary.

[0016] In particular, the invention makes it possible to install the reducer components and the motor in the same housing. Therefore, there are few restrictions on the installation of the motor in the reducer housing, especially because the system for cooling it is more compact than a water cooling system.

[0017] Other advantageous and non-limiting features of the reducer according to the invention - either individually or in any technically possible combination - are as follows:

[0018] - the electric motor and the pump are housed in the above-mentioned housing;

[0019] - providing a reduction gear, the input of which is coupled to the output shaft of the electric motor and the output of which is coupled to the pump;

[0020] -The reduction ratio of the reduction gear is less than 1 / 2;

[0021] - the housing defines three separate chambers, including a first chamber accommodating the motor, a second chamber accommodating the reduction gear, and a third chamber accommodating the pump;

[0022] - a sealing device is provided between at least the second and third chambers;

[0023] - the motor, reduction gear and pump have a common axis of rotation;

[0024] - the reduction device and / or the pump comprises a drive shaft aligned with the output shaft of the electric motor and having an internal longitudinal duct through which the lubricating fluid flows;

[0025] - the output shaft of the electric motor has, over at least a portion of its length, an internal longitudinal duct through which the lubricating fluid flows;

[0026] The output shaft of the electric motor has at least one radial opening, so that the lubricating fluid flowing in the internal longitudinal duct can be ejected from the output shaft.

[0027] The present invention also provides a motor vehicle with a powertrain, wherein the powertrain includes the internal combustion engine and a reducer.

[0028] Of course, the various features, variants and embodiments of the present invention can be associated with each other in various combinations, as long as they are not incompatible or mutually exclusive. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following description of the invention, together with the accompanying non-limiting drawings, will clearly explain what the invention consists of and how to implement the invention.

[0030] In the attached figure:

[0031] [ Figure 1 ] is a schematic diagram of a gearbox according to the present invention.

[0032] [ Figure 2 ]yes Figure 1 A view of a portion of the gearbox housing showing the electric motor coupled to the reduction gear and the pump on the left side.

[0033] [ Figure 3 ]yes Figure 2 A cross-sectional view of a portion of the housing is shown showing the motor, reduction gear and pump.

[0034] [ Figure 4 ]yes Figure 1 An exploded view of the first section of the gearbox is shown in FIG.

[0035] [ Figure 5 ]yes Figure 1 Exploded view of the second part of the gearbox, where Figure 4 The part in is shown in the assembled position.

[0036] [ Figure 6 ]and Figure 3 Similarly, the oil circuit is shown.

[0037] Figure 1 A gearbox of a powertrain is shown. Specifically, it is a gearbox 10, but alternatively it can be a simpler gearbox (single ratio or even double ratio).

[0038] The powertrain is preferably designed to be installed in a motor vehicle. The motor vehicle can take various forms. For example, it can be a truck, a motorcycle, an airplane, a boat, etc. However, it is preferably a car.

[0039] This powertrain is called a hybrid and includes an internal combustion engine (not shown) and an electric motor 200 .

[0040] Typically, an internal combustion engine has a crankshaft coupled to a transmission 10 , possibly via a clutch.

[0041] Electric motor 200 may function as a motor (whose torque is added to that produced by the internal combustion engine), as an alternator (whose torque is subtracted from that produced by the internal combustion engine), or as both, depending on the conditions encountered.

[0042] The electric motor 200 is coupled to the rest of the powertrain at the gearbox 10. This is referred to as a hybrid gearbox 10.

[0043] like Figure 1 As shown, the gearbox generally includes a housing 100 that houses shafts 20, 30 and pinions 40, 50 to provide multiple gear ratios. Such a gearbox can take various forms: manual gearbox, robotic gearbox, automatic gearbox, etc.

[0044] Typically, a gearbox may include two shafts 20, 30 on which face-to-face meshing pinions 40, 50 of different diameters are provided, the pinion 50 of one of the shafts 30 being, for example, idlingly mounted on the shaft (i.e., freely rotating on the shaft), while the other pinion is fixedly mounted on the other shaft 20. To change the gear ratio, such a gearbox 10 uses a coupling device (called a shifter) designed to couple one of the idler pinions 50 to the shaft 30 so as to make their rotational speeds equal.

[0045] This gearbox 10 also houses a main lubrication and cooling circuit 60 which takes lubricating fluid (eg oil) from the bottom of the housing 100 and sprays it everywhere where lubrication and cooling are required.

[0046] This part of the gearbox 10 will not be described in further detail here as it is well known.

[0047] The housing 100 of the gearbox defines a main chamber that accommodates the shafts 20 , 30 and the pinions 40 , 50 .

[0048] Here, the housing 100 has a protruding portion so that it can accommodate in particular the electric motor 200 .

[0049] Figure 2 The protrusion is shown in more detail on the right side of FIG.

[0050] The protrusion comprises several parts so as to make it easier to assemble the hybrid gearbox assembly. It is formed by four parts 110, 120, 130, 140 which are fixed together to accommodate the electric motor 200 as well as the reduction gear 300 and the oil pump 400 (these three elements 200, 300, 400 are in Figure 2 Detailed illustration on the left side of the figure).

[0051] The idea here is that the housing 100 not only houses the motor 200, but also houses an oil pump 400 designed specifically and exclusively for cooling and lubricating the motor 200. The reduction gear 300 is then used so that the motor 200 can mechanically actuate the oil pump 400 at a desired speed to ensure cooling and lubrication of the motor.

[0052] It should be noted that once the motor 200 starts to rotate, the speed is not zero. Since the oil pump 400 is constantly meshed with the motor 200 through the reduction gear 300, its speed will depend on the speed of the motor 200, and thus the flow rate of oil used to cool and lubricate the motor 200 will be a function of the motor speed (a linear function in this case).

[0053] According to the present invention, the oil used for this purpose is the same as the oil used for cooling and lubricating other parts of the gearbox. In this case, the oil will be taken out from the bottom of the housing 100.

[0054] Here, the motor 200 , the reduction gear 300 , and the oil pump 400 are sequentially stacked on the same axis (referred to as the rotation axis A1 ) to reduce the floor space.

[0055] For simplicity, in the rest of this specification, the terms "right" and "left" are used in view of the orientation of the three elements 200, 300, and 400 in the various figures, so that the motor 200 is located on the left side of the reduction gear 300, and the reduction gear 300 itself is located on the left side of the oil pump 400.

[0056] At this point, we may describe the three elements 200, 300, 400 in more detail.

[0057] like Figure 2 and Figure 3 As shown, the electric motor 200 generally includes a rotor 230 (eg, a permanent magnet rotor or a wound rotor), and a stator 220 located around the rotor 230 , the stator 220 including electrical coils for establishing a rotating magnetic field suitable for the rotation of the rotor.

[0058] The rotor 230 is equipped with an output shaft 201, which is thus suitable for rotating about the axis of rotation A1. To this end, the output shaft 201 is equipped with two ball bearings that engage in openings provided in two flanges 210, 211 fixed to both sides of the stator 220. The two flanges are fixed in place by bolts.

[0059] Figure 3 The left end of the output shaft 201 is shown to be solid and to carry a fixed pinion 240 for coupling the output shaft 201 to a shaft 20 of the gearbox 10 .

[0060] It can be seen that the right end of the shaft is hollow. A longitudinal hole 201A is provided, which extends along the rotation axis A1 over most of the length of the shaft. Therefore, the longitudinal hole 201A is open on the oil pump 400 side and, as will be clear later, allows oil to enter the interior of the motor 200. In order to exit from the longitudinal hole 201A, two sets of radial openings 201B are provided, which are located close to the two ball bearings, allowing oil to be sprayed into them and the stator winding 220 to cool and lubricate the entire motor 200.

[0061] like Figure 4 As shown, the motor 200 is fixed to the first part 110 of the housing 100 by screws 111, here there are four screws. It can also be seen that two centering pins 112 are used to adjust the position of the motor 200 relative to the first part 110 of the housing 100 as much as possible.

[0062] like Figure 4 As shown, the second part 120 of the housing 100 is then screwed onto the first part 110 to enclose the motor 200. Of course, this closure is not complete, because an opening is provided so that the oil entering the motor 200 can flow to the bottom of the housing through the opening under the action of gravity (the opening is provided for this purpose).

[0063] The first and second parts 110, 120 of the housing 100 together define a space for the motor 200, which space forms part of the first chamber (it should be remembered that this chamber houses the gearbox shaft and the pinion). Therefore, the oil flowing into this space by gravity will naturally drain to the bottom of the housing 100, that is, to the bottom of the first chamber 200A defined by the housing 100.

[0064] The first part 110 of the housing 100 includes a main wall that is generally flat and orthogonal to the rotation axis A1, and has a flange-shaped edge for fixing to the second part 120 of the housing 100. The second part includes a side wall that is bent around the motor 200. The second part 120 is open on the same side as the first part 110 of the housing, but is closed at the opposite end by a generally flat wall, and an opening 121 is provided at the center of the flat wall for the right end of the output shaft 201 of the motor 200 to pass through.

[0065] The seal at the opening 121 is provided by a seal 122, preferably a lip seal, to withstand the high speed rotation of the output shaft 201. The seal is fixed in the opening 121 so that its lip rests on the output shaft.

[0066] The reduction gear device 300 is directly coupled to the output shaft without any components therebetween.

[0067] The reduction gear device 300 may take many different forms.

[0068] In any case, it is designed to provide a reduction ratio of less than 1 / 2, which value enables the oil pump 4000 to run at a speed compatible with the motor 200. Typically, the reduction ratio may be between 1 / 8 and 1 / 10.

[0069] Preferably, the reduction gear 300 is of an epicyclic type, and its input axis and output axis are also preferably coaxial.

[0070] In this case, if Figure 4 As shown, the reduction gear comprises a fixed annular gear 340 , a planetary central pinion 310 and a planetary gear carrier 320 . The planetary gear carrier 320 is equipped with at least one satellite pinion 330 . The satellite pinion 330 is meshed with the central pinion 310 and the fixed annular gear 340 .

[0071] The fixed ring gear 340 is forcibly engaged in a hole in the second part 120 of the housing 100. The hole is recessed on the right side of the second part 120 of the housing 100 so that the bottom of the hole is formed by a wall in which an opening 121 is located for passage of the motor output shaft 201. The outer surface of the fixed ring 340 matches the shape of the hole, and its inner surface has straight teeth evenly distributed around the rotation axis A1.

[0072] The central pinion 310 is mounted on the right end of the output shaft 201 of the motor 200 and is fixedly mounted relative to the output shaft 201, for example by forced adaptation or by a spline connection coupled to an axial stop (here a circlip 311). Of course, other connection methods can also be used.

[0073] The planetary carrier 320 comprises a shaft (called "drive shaft 301"), the left end of which is fixed to a flange, here in the shape of a cross, each branch of which extends radially relative to the axis of rotation A1. Each end of these branches has a shaft on which the satellite pinions 330 are mounted so as to be free to pivot about an axis parallel to the axis of rotation A1.

[0074] Thus, when the central pinion 310 pivots, the satellite pinions 330 rotate, orbiting around the circumference of the fixed ring gear 340 , which forces the drive shaft 301 to rotate around the axis of rotation A1 at a lower speed (but dependent on the speed of the output shaft 201 of the motor 200 ).

[0075] like Figure 3 As shown, the reduction gear device 300 is designed to be accommodated in a second chamber 300A defined by the housing 100 , which can be sealed relative to the first chamber 200A.

[0076] For this reason, Figure 5As shown, the housing 100 comprises a third tubular portion 130, the left end of which is attached to the second portion 120 of the housing and the right end of which is closed by a flat wall.

[0077] The wall has a central opening 131 for the drive shaft 301 to pass through.

[0078] The seal at the opening 131 is provided by a seal 132, preferably a lip seal, to withstand the high speed rotation of the drive shaft 301. The seal is fixed in the opening 131 with its lip against the drive shaft 301.

[0079] The drive shaft 301 is then mounted in the third portion 130 of the housing 100 , free to rotate about the axis of rotation A1 via a ball bearing 133 which engages with a housing in the third portion 130 close to the opening 131 .

[0080] It should be noted that the static seal between the second part 120 and the third part 130 of the housing 100 is achieved by means of a flat gasket 134. They are fixed by means of screws.

[0081] Figure 5 It is shown that the third part 130 of the housing is provided with two centering pins 136 on each of its two faces, so that the different parts of the housing 100 can precisely match each other, thereby ensuring perfect matching between the axis of the output shaft 201 and the axis of the drive shaft 301.

[0082] like Figure 3 As shown, the drive shaft 301 is hollow. A longitudinal hole 301A is provided, which extends along the rotation axis A1 over the entire length of the shaft. This longitudinal hole 301A is therefore open on the oil pump 400 side and on the motor 200 side, and as will become clear in the rest of this description, the longitudinal hole 301A allows oil to enter the interior of the motor 200. The longitudinal hole 301A is here connected to the output shaft 201 via a sleeve 500, which is contracted into the output shaft 201 (and thus fixed on the output shaft 201) and is free to pivot relative to the drive shaft 301.

[0083] like Figure 3 and Figure 5 As shown, the oil pump 400 is then installed into the right side of the third portion 130 of the housing 100 and into the sealed chamber 400A defined by the third portion 130 and the fourth portion 140 of the housing 100 .

[0084] The oil pump 400 is mounted directly on the drive shaft 131, which reduces its overall size. Therefore, the oil pump 400 is centered on the rotation axis A1.

[0085] Different types of pumps can be used. Typically, a vane pump or an internal crescent gear pump is used.

[0086] However, in this case, the choice was to use a positive displacement pump with an eccentric rotor.

[0087] The flow rate of this type of pump depends directly on the rotation speed of the drive shaft 301 , which is fully adapted to the needs of the electric motor 200 .

[0088] like Figure 5 As shown, it comprises a toothed wheel 420 having a central opening through which the toothed wheel 420 is fixedly mounted on the drive shaft 301. This mounting can be done by force or by contraction. However, here it is chosen to use a key, which is locked in a groove in the drive shaft 301 and in the central opening of the toothed wheel 420. The right end of the drive shaft 301 is threaded so that a nut 421 can be screwed on to lock the gear 420.

[0089] In the same manner as the second part 120 of the housing 100, a hole is provided in the third part 130 of the housing 100. The hole is recessed on the right side of the third part 130 of the housing 100 so that the bottom of the hole is formed by a wall in which an opening 131 for the drive shaft 301 to pass is located.

[0090] The pump has an internally toothed eccentric ring 410 which sits within the bore.

[0091] Thus, when the gear 420 rotates, it drives the eccentric ring 410, thereby pumping oil from one side of the bore and back to the other side.

[0092] Then two coaxial holes 137, 138 opposite to each other are arranged at the edge of the hole. One of these holes 137 is unscrewed so that a connector can be screwed therein, thereby being able to connect the hole to the bottom of the housing 100, where the oil is taken.

[0093] The outer end of the other hole 137 is closed by the first plug. On the other hand, the hole is connected to the conduits recessed in the third and fourth parts 130 and 140 of the housing 100 to guide the oil from the hole to the right end of the drive shaft 301.

[0094] The fourth part 140 of the housing 100 is designed to rest against the third part 130 to close the pump 400. For this purpose, it is disc-shaped and drilled with four lugs for the passage of screws which will pass through the third part of the housing 100 and screw into the second part 120.

[0095] A flat gasket 145 is used to provide a static seal between the two housing components 130 , 140 .

[0096] like Figure 5 As shown, the fourth portion 140 of the housing 100 has a protrusion protruding from its outer surface, which extends radially in length relative to the rotation axis A1. The protrusion defines a radial duct 142 inside, which allows the oil from the pump 400 to be conveyed along the rotation axis A1 to a longitudinally arranged orifice in the housing. The orifice is connected to the inside of the drive shaft 301 through a sleeve 501, which is retracted into the housing and can freely pivot relative to the shaft.

[0097] Figure 6 The flow path of the oil is shown. It can be seen that the oil arrives through the first hole 137 and flows into the second hole 138 through the pump 400. The intermediate duct 141 then allows the oil to flow (parallel to the axis of rotation A1) to the radial duct 142 provided in the fourth part 140 of the housing 100. In this way, the oil can pass through the axial aperture, then through the drive shaft 301, and then through the output shaft 201, thereby entering the motor 200.

[0098] Here, the first hole 137, the intermediate duct 141 and the radial ducts 142 are made by drilling, which explains the placement and use of plugs 139, 149 at their outlets to the outside. Alternatively, they can be made in another way, for example at the casting stage of the housing, or they can be replaced by external ducts to guide the oil flow from the delivery area of ​​the pump to the return shaft.

[0099] The gearbox 10 operates as follows.

[0100] When the output shaft 201 of the motor 200 is subjected to a rotation speed Ω1, the motor 200 drives the driving shaft 301 at a reduced rotation speed Ω2 through the reduction gear 300 to adapt to the operation of the oil pump 400.

[0101] When the toothed wheel 420 is driven to rotate, the toothed wheel 420 will cause the eccentric ring 410 to perform an eccentric circular motion, which will generate suction on one side of the hole 137 and pressure on the opposite side.

[0102] The oil flow will be axially returned along the two shafts 201, 301 due to the ducts inside the housing 100 (the ducts provide sealing between the housing 100 and the drive shaft 301 and between this drive shaft and the output shaft 201). Finally, radial holes provided in the output shaft 201 will supply oil to the moving parts and bearings of the motor 200.

[0103] Due to the rotation speed of the motor 200 and these radial holes, the oil is naturally projected to these different components. Then, the oil falls directly to the bottom of the housing 100 by dripping along the wall of the housing.

[0104] The oil flow rate for lubricating and cooling the motor can be more than 2 L / min at most, in this case, when the motor speed reaches 18000 rpm, the oil flow rate is about 6 L / min.

[0105] At this stage, it should be noted that the oil supply circuit of the oil pump 400 preferably includes a non-return valve (not shown) to prevent the oil pump 400 from being higher than the oil level in the gearbox. It may also include a heat exchanger to cool the oil.

[0106] It should also be noted that lubrication of the reduction gear unit can be performed in several ways. By enclosing the lubricant in chamber 300A when the gearbox is assembled, lifetime lubrication can be used. Alternatively, a filling plug can be provided in the housing so that lubricant can be added to chamber 300A and drained as needed. Alternatively, an orifice can be provided in the wall separating the above-mentioned chambers 200A and 300A so that oil from the motor can be sprayed onto the reduction gear unit 300.

[0107] The invention is in no way limited to the embodiments described and shown, but a person skilled in the art will know how to apply any variant according to the invention.

[0108] In particular, the oil for lubricating the gearbox components and the motor 100 may not be stored at the bottom of the housing, but may be stored in a dedicated oil tank outside the housing and below the housing.

Claims

1. A speed reducer (10), comprising a housing (100) accommodating at least one shaft (20, 30) and at least one pinion (40, 50), and comprising a cooling and lubricating circuit (60), wherein the cooling and lubricating circuit (60) is suitable for spraying lubricating liquid onto the shaft (20, 30) and / or the pinion (40, 50), It is characterized in that The reducer (10) further includes: An electric motor (200) comprising an output shaft (201) coupled to the at least one shaft (20, 30), and A pump (400) is actuated by the motor (200) and is adapted to cool and lubricate the motor (200) using the lubricating fluid.

2. The reducer (10) according to claim 1, wherein: The motor (200) and the pump (400) are accommodated in the housing (100).

3. The reducer (10) according to claim 1 or 2, wherein: A reduction gear (300) is provided, wherein an input of the reduction gear (300) is coupled to the output shaft (201) of the motor (200), and an output of the reduction gear (300) is coupled to the pump (400).

4. The reducer (10) according to claim 3, wherein: The reduction ratio of the reduction device (300) is less than 1 / 2.

5. The reducer (10) according to claim 3 or 4, wherein: The housing (100) defines three separate chambers, namely a first chamber (200A) accommodating the motor (200), a second chamber (300A) accommodating the reduction device (300), and a third chamber (400A) accommodating the pump (400), and a sealing device is provided at least between the second chamber (300A) and the third chamber (400A).

6. The reducer (10) according to any one of claims 3 to 5, wherein: The motor (200), the reduction gear (300) and the pump (400) have a common rotation axis (A1).

7. The reducer (10) according to any one of claims 3 to 6, wherein: The reduction device (300) and / or the pump (400) comprises a drive shaft (301) aligned with the output shaft (201) of the motor (200) and having an internal longitudinal conduit (301A) through which the lubricating fluid flows.

8. The reducer (10) according to any one of claims 1 to 7, wherein: The output shaft (201) of the motor (200) has an internal longitudinal conduit (201A) over at least a portion of its length, through which the lubricating fluid flows.

9. The reducer (10) according to claim 8, wherein: The output shaft (201) of the motor (200) has at least one radial opening (201B), and the at least one radial opening (201B) allows the lubricating fluid circulating in the internal longitudinal pipe (201A) to be ejected from the output shaft (201).

10. A motor vehicle comprising a powertrain, the powertrain comprising an internal combustion engine and a reducer (10), characterized in that: The reducer (10) is a reducer (10) according to any one of the preceding claims.

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