Device for transmitting power between the output of a thermal engine and a wheel shaft, and use of said device

1. Power transmission device comprising:

an input shaft intended to be connected to a heat engine, and an output shaft intended to be connected to a wheel shaft,

a first and a second electric machine respectively comprising a stator and a rotor, each machine respectively being equipped with a shaft, and

a mechanical assembly providing the mechanical connection between the input shaft, the output shaft, and the shafts of the machines,

wherein

at least one of the electric machines comprises a rotating rotor and a rotating stator each directly connected to the mechanical assembly, and

the device comprises a switching device mounted on the shaft of one of the electric machines, this switching device enabling the shaft of the machine to be selectively and directly connected to two different elements of the mechanical assembly in order to change an operating mode of the power transmission device.

2. Device according to claim 1 , wherein:

the rotational speed of the electric machine that carries the switching device is proportional solely to the rotational speed of a plurality of wheels or of the engine when the shaft of said machine is connected to one of the two elements of the mechanical assembly, and

the rotational speed of the electric machine that carries the switching device is dependent on the rotational speeds of the wheels and of the engine when the shaft of the machine ( 6 , 7 ) is connected to another element of the mechanical assembly.

3. Device according to claim 2 , wherein both electric machines have rotating stators, and the mechanical assembly does not include a planetary gear train.

4. Device according to claim 2 , wherein one of the machines has a rotating stator and the other has a fixed stator, and the mechanical assembly comprises only one planetary gear train, made up of a sun gear, a planet carrier with planet gears, and a ring gear that intermesh.

5. Device according to claim 4 , wherein the input shaft is directly connected to the planet carrier, and the output shaft is connected to an intermediate shaft via a differential with a ratio of μ 1 , said intermediate shaft being connected to the ring gear via a first gear assembly with a ratio of μ 0 .

6. Device according to claim 5 , wherein the shaft of the machine with the fixed stator is selectively connectable to the ring gear via a second gear assembly with a ratio of r 2 , or to the sun gear via a third gear assembly with a ratio of r 3 .

7. Device according to claim 1 , wherein both electric machines have rotating stators, and the mechanical assembly does not include a planetary gear train.

8. Device according to claim 7 , wherein the output shaft is connected to an intermediate shaft via a differential with a ratio of μ 1 , said intermediate shaft being connected to the input shaft via a first gear assembly with a ratio of μ 0 .

9. Device according to claim 8 , wherein the rotor of the first machine is connected to a plurality of wheels via a second gear assembly with a ratio of q 1 , and the stator of this machine is connected to the input shaft via a third gear assembly with a ratio of q 2 .

10. Device according to claim 9 , wherein the rotor of the second machine is selectively connectable to the output shaft via a fourth gear assembly with a ratio of r 2 or via a fifth gear assembly with a ratio of q 3 , respectively by means of a first dog clutch and a second dog clutch, and

the stator of the second machine is selectively connectable to the input shaft via a sixth gear assembly with a ratio of q 4 or to a fixed frame, respectively by means of a third dog clutch and a fourth dog clutch.

11. Device according to claim 10 , wherein μ 0 =−0.15; μ 1 =−1.65; r 2 =−0.25; r 3 =−0.89; q 1 =−0.26; q 2 =−0.50; q 3 =0.49; q 4 =0.32.

12. Device according to claim 1 wherein one of the machines has a rotating stator and the other has a fixed stator, and the mechanical assembly comprises only one planetary gear train, made up of a sun gear, a planet carrier with planet gears, and a ring gear that intermesh.

13. Device according to claim 12 , wherein the input shaft is directly connected to the planet carrier, and the output shaft is connected to an intermediate shaft via a differential with a ratio of μ 1 , said intermediate shaft being connected to the ring gear via a first gear assembly with a ratio of μ 0 .

14. Device according claim 13 , wherein the shaft of the machine with the fixed stator is selectively connectable to the ring gear via a second gear assembly with a ratio of r 2 , or to the sun gear via a third gear assembly with a ratio of r 3 .

15. Device according to claim 14 , wherein the stator of the machine with the rotating stator is connected to the input shaft via a fourth gear assembly with a ratio of q 2 , and the rotor of the machine with the rotating stator is connected to the sun gear via a fifth gear assembly with a ratio of q 1 .

16. Device according claim 15 , wherein μ 0 =−0.15; μ 1 =−1.65; r 2 =−0.25; r 3 =−0.89; q 1 =−0.26; q 2 =−0.50.

17. Device according to claim 12 , wherein the shaft of the machine with the fixed stator is selectively connectable to the ring gear via a first gear assembly with a ratio of r 2 , or to the sun gear via a second gear assembly with a ratio of r 3 .

18. Method of transmitting power using the device according to claim 10 , comprising:

switching the switching device so as to change between the operating mode of the power transmission device and other operating modes of the power transmission device, wherein the operating modes include:

a coupled-output mode of the power transmission device, wherein the first and fourth dog clutches are closed, and the second and third dog clutches are opened, and

a combined mode of the power transmission device, wherein the second and third dog clutches are closed, and the first and fourth dog clutches are opened.

19. Method according to claim 18 , comprising, in order to change from the coupled-output mode to the combined mode:

disengaging the first dog clutch while the fourth dog clutch remains engaged,

synchronizing a rotational speed of the rotor of the second machine with a first idler gear connectable to the second dog clutch,

then engaging the second dog clutch,

disengaging the fourth dog clutch,

synchronizing the rotational speed of the stator of the second machine with a second idler gear connectable to the third dog clutch, and

engaging the third dog clutch with this gear.

20. Method according to claim 18 , comprising, in order to change from the combined mode to the coupled-output mode:

disengaging the third dog clutch,

stopping the stator of the second machine,

engaging the fourth dog clutch with the frame,

opening the second dog clutch,

synchronizing the rotor of the second machine with an idler gear connectable to the first dog clutch, and

engaging the first dog clutch with the idler gear.