ELECTRIC VEHICLE PROPULSION SYSTEM

Abstract

A propulsion system for an electric vehicle including a first electric propulsion motor comprising a stator and a rotor having a first output shaft able to rotate about a first axis, a second electric propulsion motor comprising a stator and a rotor having a second output shaft able to rotate about a second axis, a first reducer able to receive the torque supplied by the first electric motor, via a first selective or non-selective coupling system, this first reducer having a first reduction ratio, a second reducer able to receive the torque supplied by the second electric motor, via a second selective or non-selective coupling system, this second reducer having a second reduction ratio, a third coupling system, which may or may not be selective, for coupling the first output shaft and the second output shaft, and the first axis and the second axis not being coincident.

Claims

1. A propulsion system for an electric vehicle, comprising: a first electric propulsion motor comprising a stator and a rotor having a first output shaft able to rotate about a first axis, a second electric propulsion motor comprising a stator and a rotor having a second output shaft able to rotate about a second axis, a first reducer able to receive the torque supplied by the first electric motor, via a first selective or non-selective coupling system, this first reducer having a first reduction ratio, a second reducer able to receive the torque supplied by the second electric motor, via a second selective or non-selective coupling system, this second reducer having a second reduction ratio, a third coupling system, which may or may not be selective, for coupling the first output shaft and the second output shaft, the first axis and the second axis not being coincident.

2. The propulsion system as claimed in claim 1, the first axis and the second axis being parallel.

3. The propulsion system as claimed in claim 1, the first reducer being connected to the first output shaft of the first electric motor via a first selective or non-selective coupling system.

4. The propulsion system as claimed in claim 1, the second reducer being connected to the second shaft of the second electric motor via the second selective or non-selective coupling system.

5. The system as claimed in claim 1, each coupling system employing a clutch.

6. The system as claimed in claim 3, the first coupling system and the second coupling system employing a clutch, and the third coupling system employing a dog clutch, or being non-selective.

7. The system as claimed in claim 3, the first coupling system and the second coupling system employing a dog clutch, and the third coupling system employing a dog clutch, or being non-selective.

8. The system as claimed in claim 1, comprising a differential arranged in such a way as to receive at least one of: the torque passing via the first reducer, and the torque passing via the second reducer.

9. The system as claimed in claim 3, comprising a control member for controlling the first, second and third coupling system so that the propulsion system can adopt all or some of the following configurations: a configuration (i) whereby the differential receives the torque passing via the first reducer, this torque being generated by the first electric motor, a configuration (ii) whereby the differential receives the torque passing via the second reducer, this torque being generated by the second electric motor, a configuration (iii) whereby the differential receives the torque passing via the first reducer, this torque being generated by the first electric motor, and also the torque passing via the second reducer, this torque being generated by the second electric motor, a configuration whereby the differential receives the torque passing via the first reducer, this torque being generated by the first electric motor, and by the second electric motor or, where appropriate, only by the second electric motor, and a configuration whereby the differential receives the torque passing via the second reducer, this torque being generated by the first electric motor and by the second electric motor or, where appropriate, only by the first electric motor, and a parking-brake configuration (vi) in which the three coupling systems are in the coupled configuration.

10. The system as claimed in claim 1, comprising at least one of: two of the first reducers, with first reduction gear ratios that differ from each other, being arranged in parallel, and two of the second reducers, with second reduction gear ratios that differ from each other, being arranged in parallel.

11. The system as claimed in claim 3, the third coupling system comprising at least one element which belongs neither to the first coupling system, nor to the second coupling system.

Description

[0057] The invention may be better understood on reading the following description of nonlimiting exemplary embodiments thereof and on studying the appended drawing, in which:

[0058] FIG. 1 is an elevation view of a propulsion system according to one embodiment of the invention,

[0059] FIG. 2 schematically depicts the propulsion system of FIG. 1,

[0060] FIGS. 3 to 7 are variants of FIG. 2,

[0061] FIG. 8 depicts a clutch that can be used to create a first or second coupling system, and

[0062] FIG. 9 depicts a dog clutch that can be used to create a first or second or third coupling system.

[0063] FIG. 1 depicts a vehicle propulsion system 1 according to a first embodiment of the invention.

[0064] This propulsion system 1 is, in this instance, purely electrical, which means to say that it does not employ any combustion engine to drive the vehicle which in this instance is an automobile. This propulsion system 1 here comprises a first electric motor 10 and a second electric motor 11.

[0065] The first electric motor 10 and the second electric motor 11 are, for example, permanent-magnet synchronous machines. The first electric motor 10 for example has a nominal torque of 50 Nm, while the second electric motor 11 for example has a nominal torque of 70 Nm. As can be seen in FIG. 1, the first electric motor 10, 11 has, in the example described, a rotor with a first output shaft rotating about a first axis of rotation X1, and the second electric motor 11 has, in the example described, a rotor having a second output shaft rotating about a second axis of rotation X2. In the example described, the axes of rotation of the first electric motor and of the second electric motor are parallel but not coincident, the two electric motors 10 and 11 not having their axes of rotation aligned.

[0066] In the example described with reference to FIGS. 1 and 2, the first output shaft is connected to a first coupling system 20 which in this instance is a selective-coupling system. This coupling system 20 is depicted in the form of a clutch in FIGS. 1 and 2, but could be produced in some other way, for example using a dog clutch.

[0067] This first coupling system 20 allows the first output shaft of the first electric motor 10 to be coupled to a first reducer 21 which, for example, has a reduction ratio of the order of 12.

[0068] The second output shaft of the second electric motor 11 is, according to the example described with reference to FIGS. 1 and 2, connected to a second coupling system 22 which in this instance is a selective-coupling system. Similarly to that which was mentioned in respect of the first coupling system 20, this system is depicted in the form of a clutch in FIGS. 1 and 2, but could be produced in some other way, for example using a dog clutch.

[0069] FIG. 8 depicts an example of a clutch suitable for embodying the first coupling system 20 or for embodying the second coupling system 22. This clutch in this instance is a plate clutch, these plates 26 becoming coupled in order to transmit torque, under the action of a mobile piston.

[0070] In a variant, each coupling system 20, 22 could employ a dog clutch, as depicted in FIG. 9. Such a coupling system allows two components to be coupled using dogs 27.

[0071] The second coupling system 22 allows the second output shaft of the second electric motor 11 to be coupled to a second reducer 23 which, for example, has a reduction ratio of the order of 8.

[0072] The invention is not restricted to the positioning of the first or, respectively, second, coupling system 20 or, respectively, 22, upstream of the first reducer 21 or, respectively, second reducer 23, in the path of the torque generated by the corresponding motor 10 or, respectively, 11. The first or, respectively, second, coupling system 20 or, respectively, 22, may, as a variant, be positioned downstream of the first reducer 21 or, respectively, second reducer 23, in the path of the torque generated by the corresponding motor 10 or, respectively, 11.

[0073] The propulsion system 1 further comprises a differential 30. In the examples considered, one or more gear wheels 32 are interposed between the first reducer(s) 21 and the differential 30 and between the second reducer(s) 23 and the differential 30. However, in variants, it is possible for no gear wheel to be provided.

[0074] In the example of FIGS. 1 and 2, the propulsion system 1 comprises just one single first reducer 21 and just one single second reducer 22, but the invention is not restricted to that scenario.

[0075] Thus, as depicted in FIGS. 5 and 6, several first reducers 21 may be arranged in parallel between the first shaft of the first electric motor and the differential 30, and several second reducers 23 may be arranged in parallel between the second shaft of the second electric motor 11 and the differential 30.

[0076] As may be seen in FIGS. 5 and 6, two first reducers 21 may be arranged in parallel, and two second reducers 23 are arranged in parallel. The two first reducers 21 here have a first reduction ratio that differs from one to the other, just like the two second reducers 23. Where appropriate, a selection member 33 for selecting one of the first reducers 21 and a selection member 34 for selecting one of the second reducers 23 may be provided. Each of these selection members 33, 34 is in this instance a dog clutch.

[0077] In the example of FIG. 5, the first coupling system 20 and the selection member 33 are associated with the first reducers 21, and the second coupling system 22 and the selection member 34 are associated with the second reducers 23.

[0078] In the example of FIG. 6, there is no first coupling system 20 and 22; the function of uncoupling of the reducers 21 and 23 is performed by the selection members 33 and 34.

[0079] It is also possible for the selection members 33 and 34 to be present in instances in which the propulsion system comprises a single first reducer 21 and a single second reducer 22. This selection member 33, 34 therefore allows the corresponding reducer 21, 23 to be uncoupled from its downstream side.

[0080] The differential 30 is arranged in such a way as to receive, in the examples described:

[0081] the torque available on the first shaft of the first electric motor 10, after passing via the first coupling system 20, where present, and the first reducer 21, and/or

[0082] the torque available on the second output shaft of the second electric motor 11, after passing via the optional second coupling system 22, where present, and the second reducer 23 in the example described.

[0083] The differential 30 allows the torque to be transmitted to the wheels 31.

[0084] As can be seen in FIGS. 1 to 7, the first output shaft of the first electric motor 10 is coupled to the second output shaft of the second electric motor 11. This coupling is done via a third coupling system 35.

[0085] This third coupling system 35 may be embodied in different ways, as will now be described.

[0086] In FIGS. 1 and 2, this third coupling system 35 is an assembly formed by a sprocket gear 52 secured to rotate as one with the first output shaft of the first electric motor 10, an idling sprocket gear 54 mounted with the ability to rotate freely on the second output shaft of the second electric motor 11, and a chain 55 meshing with each sprocket gear 52 and 54. A dog clutch 56 is provided for selectively coupling the sprocket gear 54 to the second output shaft of the second electric motor 11.

[0087] In FIG. 3, this third coupling system 35 is an assembly formed by: a pinion gear 40 secured to rotate as one with the first output shaft of the first electric motor 10, and meshing with a first pinion gear 41 secured to rotate as one with an intermediate shaft 42, a pinion gear 43 secured to rotate as one with the second output shaft of the second electric motor 11 and meshing with an idling second pinion gear 44 mounted to rotate freely on the intermediate shaft 42, and a dog clutch 45 forming a coupling member for the selective coupling of the first pinion gear 41 and of the second pinion gear 44.

[0088] In FIGS. 4 to 6, which differ from one another as has been seen in terms of the number of first reducers 21 and second reducers 23 and in terms of the presence or absence of the first coupling system 20 and the second coupling system 22, the third coupling system is an assembly formed by a pinion gear 45 secured to rotate as one with the first output shaft of the first electric motor 10, an idling pinion gear 47 mounted to rotate freely on the second output shaft of the second electric motor 11, a first pinion gear 48 secured to rotate as one with an intermediate shaft 49 and meshing with the pinion gear 45, a second pinion gear 50 secured to rotate as one with the intermediate shaft 49 and meshing with the pinion gear 47, and a dog clutch 46 allowing the pinion gear 47 to be selectively coupled to the second output shaft on which it is mounted. In a variant, the pinion gears 48, 50 and the intermediate shaft 49 may be omitted, the idling pinion gear 47 meshing directly with the pinion gear 45.

[0089] In FIG. 7, the third coupling system is an assembly formed by a sprocket gear 52 secured to rotate as one with the first output shaft of the first electric motor 10, a sprocket gear 53 secured to rotate as one with the second output shaft of the second electric motor 11, and a chain 55 meshing with each sprocket gear 52 and 53. No selective-coupling means is provided here, the third coupling system 35 not being selective in this instance.

[0090] Other examples are possible for embodying a selective or non-selective third coupling system, for example a clutch.

[0091] In an additional variant, the first coupling system 20 and the second coupling system 22 employ dog clutches, and the third coupling system 35 employs a clutch.

[0092] Throughout the foregoing, the propulsion system may further comprise a control member 50 for controlling the first 20, second 22 and third 35 coupling systems when these three coupling systems are present. When several first reducers 21 and/or several second reducers 23 are present, the control member 50 may also make it possible to select one of the reducers, where appropriate via a module specific to these first reducers or to these second reducers, this specific module operating a selection member 33 or 34 as mentioned hereinabove. As already mentioned, these selection members may be present with a single first reducer and a single second reducer, in which case they can be controlled by the control member 50, without there necessarily having to be a first coupling system 20 and a second coupling system 22.

[0093] The control member 50 is programmed so that the propulsion system can adopt the following configurations:

[0094] a configuration (i) whereby the differential 30 receives the torque passing via the first reducer 21, this torque being generated by the first electric motor 10,

[0095] a configuration (ii) whereby the differential 30 receives the torque passing via the second reducer 23, this torque being generated by the second electric motor 11,

[0096] a configuration (iii) whereby the differential 30 receives the torque passing via the first reducer 21, this torque being generated by the first electric motor 10, and also the torque passing via the second reducer 23, this torque being generated by the second electric motor 11,

[0097] a configuration (iv) whereby the differential 30 receives the torque passing via the first reducer 21, this torque being generated by the first electric motor 10, and by the second electric motor 11 or, where appropriate, only by the second electric motor 11 when the first electric motor 10 is switched off, and

[0098] a configuration (v) whereby the differential receives the torque passing via the second reducer 23, this torque being generated by the first electric motor 10, and by the second electric motor 11 or, where appropriate, only by the first electric motor 10 when the second electric motor 11 is switched off, and

[0099] a configuration (vi) whereby each coupling system 20, 22 and 35 is in a coupled position.

[0100] The commands used by the control member 50 to control the coupling systems in order to obtain the configurations (i) to (vi) above are given in the table below.

TABLE-US-00001 First coupling Second coupling Third coupling Configuration system (20) system (22) system (35) (i) Couple Uncouple Uncouple (ii) Uncouple Couple Uncouple (iii) Couple Couple Uncouple (iv) Couple Uncouple Couple (v) Uncouple Couple Couple (vi) Couple Couple Couple

[0101] Configuration (i) is for example suited to low vehicle speeds with low torque demands.

[0102] Configuration (ii) is for example suited to high vehicle speeds with low torque demands.

[0103] Configuration (iii) is for example suited to transient speeds, for example when making the transition from one reduction ratio to another.

[0104] Configuration (iv) is for example suited to low vehicle speeds with high torque demands.

[0105] Configuration (v) is for example suited to high vehicle speeds with high torque demands.

[0106] Configuration (vi) is for example suited to operation as a parking brake.

[0107] The invention is not limited to the examples that have been described above.