Hybrid powertrain

• US 6,740,002 B1
• Filed: 04/21/2000
• Issued: 05/25/2004
• Est. Priority Date: 10/21/1997
• Status: Expired due to Term

• Current Assignee: Stridsberg Licensing AB
• Original Assignee: Stridsberg Innovation AB
• Inventors: Stridsberg, Lennart
• Primary Examiner(s): HO, HA DINH
• Application Number:
  US09/557,902
• Time in Patent Office: 1,495 Days
• Field of Search: 477/2, 477/3, 477/7, 477/12, 477/14, 477/5, 475/1, 475/2, 475/3, 475/4, 475/5, 180/65.2, 180/65.4, 180/65.7
• US Class Current: 477/14
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/405 Housings
• CPC Class Codes: B60K 6/442 Series-parallel switching type
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/485 Motor-assist type
• CPC Class Codes: B60K 6/52 Driving a plurality of drive axles, e.g. four-wheel drive
• CPC Class Codes: B60K 6/54 Transmission for changing ratio
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60W 10/026 of lock-up clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data
• CPC Class Codes: F16H 2200/0047 the gear ratios comprising five forward speeds
• CPC Class Codes: H02K 51/00 : Dynamo-electric gears, i.e. dynamo-electric means for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/909 : Gearing
• CPC Class Codes: Y10S 903/91 : Orbital, e.g. planetary gears
• CPC Class Codes: Y10S 903/914 : Actuated, e.g. engaged or disengaged by electrical, hydraulic or mechanical means
• CPC Class Codes: Y10S 903/916 : with plurality of drive axles
• CPC Class Codes: Y10S 903/917 : with transmission for changing gear ratio
• CPC Class Codes: Y10S 903/919 : Stepped shift
• CPC Class Codes: Y10S 903/952 : Housing details

Abstract

A method and an apparatus control a car equipped with an automatic transmission having a lockup clutch. When the lockup clutch is in the lockup state, a variation of a generated torque is detected. When the range of the torque variation detected exceeds a predetermined value, an engine torque is reduced by controlling the engine, and the automatic transmission is controlled to compensate for a reduction of the driving torque due to a reduction of the engine torque. Thus, the speed change ratio is changed to the low gear side. The control unit includes a unit for controlling an output torque of an engine according to a command value, a unit for changing the transmission ratio of the automatic transmission, a unit for detecting a variation of the engine torque, a unit for deciding a target driving torque, a unit for reducing a torque command value when the range of a detected variation of the torque has exceeded a predetermined value when the lockup clutch was in the lockup state, and a unit for deciding a transmission ratio at which the reduction of the driving torque due to the reduction of the engine torque is compensated for.

Claims

1. A powertrain of a vehicle having wheels, the powertrain comprising

a mechanical gear box having five different gear ratios,

at least one thermal engine having an output shaft, which shaft when required can be mechanically connected to at least one of the wheels through the mechanical gear box for driving the at least one of the wheels,

an energy storage,

at least one engine side electric motor and at least one tire side electric motor, which are connected to the energy storage and are supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

connection means connected to the at least one engine side electric motor, to the at least one tire side electric motor, to the output shaft of the at least one thermal engine and to the at least one wheel for mechanically connecting the at least one engine side electric motor to the output shaft of the at least one thermal engine to be driven by the at least one thermal engine and for mechanically connecting the at least one tire side electric motor to the at least one of the wheels for driving the at least one of the wheels;

and

at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and is arranged in such a way that the mechanical connection is performed when a speed of an input shaft of the device is close to a speed of an output shaft of the device.

2. A powertrain according to claim 1, further comprising:

an input shaft coupled to the mechanical gear box wherein,

the output shaft of the at least one thermal engine when required can be mechanically connected to the input shaft of the mechanical gear box for driving the at least one wheel through the mechanical gear box, and

the connection means is arranged to mechanically connect, when the at least one thermal engine is not mechanically connected to the input shaft of the mechanical gear box, the at least one tire side electric motor to the input shaft of the mechanical gear box.

3. A powertrain according to claim 2, wherein the at least one tire side electric motor is mounted coaxially with the input shaft of the mechanical gear box and is connected to the input shaft of the mechanical gear box through a torsionally flexible coupling.

4. A powertrain according to claim 1, further comprising:

an input shaft and an output shaft coupled to the mechanical gear box wherein,

the output shaft of the at least one thermal engine when required can be mechanically connected to the input shaft of the mechanical gear box for driving the at least one wheel through the mechanical gear box, and

the connection means is arranged to mechanically connect, when the at least one thermal engine is not mechanically connected to the input shaft of the mechanical gear box, the at least one tire side electric motor to the output shaft of the mechanical gear box.

5. A powertrain according to any of claims 1-3, wherein

the mechanical gear box has an output shaft, and

at least one tire side electric motor is assembled on the output shaft of the mechanical gear box.

6. A powertrain according to any of claims 1-4, further comprising:

a differential connected between the mechanical gear box and the at least one wheel,

the at least one tire side electric motor being assembled on a separate shaft and connected to the at least one wheels through a pinion acting against a cog wheel of the differential.

7. A powertrain according to claim 1, wherein the at least one engine side electric motor is coaxial with the output shaft of the at least one thermal engine.

8. A powertrain according to claim 7, wherein each engine side electric motor is rigidly connected to the output shaft of the at least one thermal engine.

9. A powertrain according to any of claims 7-8, wherein the at least one engine side electric motor has a stator including electrically/magnetically active parts and a rotor including magnetically active parts, the magnetically active parts of the rotor being located radially outside, as seen from an axis of the motor, the electrically/magnetically active parts of the stator.

10. A powertrain according to claim 1, further comprising at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and has a thermal capacity approximately equivalent to a conventional clutch.

11. A powertrain according to claim 1, further comprising at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and has a limited thermal capacity approximately equivalent to a conventional clutch only for driving patterns adjusted to reduce the thermal load on the device.

12. A powertrain according to claim 1, further comprising at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and accepts a predetermined amount of slip.

13. A powertrain according to claim 1, further comprising means which when required performs the mechanical connection the at least one thermal engine and the at least one wheel and which comprise shifting from a gear position of the mechanical gearbox to a neutral state of the gearbox.

14. A powertrain according to claim 1, further comprising the at least one engine side electric motor has a power rating which permits the at least one engine side electric motor to absorb all power of the at least one thermal engine during gear shift operations of the mechanical gearbox even if torque and speed of the at least one thermal engine during a gear shift operation should be kept between optimal levels for a previous gear position and optimal levels for a forthcoming gear position.

15. A powertrain according to claim 1, further comprising the a least one engine side electric motor has a power rating which permits the at least one engine side electric motor to absorb all power of the at least one thermal engine during gear shift operations which are prolonged to permit slow changes in a speed of the at least one thermal engine.

16. A powertrain according to claim 1, wherein the at least one engine side electric motor has a power rating which permits the at least one engine electric motor to continuously absorb all power of the at least one thermal engine for at least one speed and torque of the at least one thermal engine at which one speed and torque the at least one thermal engine can run at more than substantially 90% of a peak efficiency of the at least one thermal engine.

17. A powertrain according to claim 1, wherein the mechanical gear box has an output shaft, which is mechanically connected to a mechanical differential driving at least two wheels of the vehicle.

18. A powertrain according to claim 1, wherein the mechanical gear box has an output shaft, which is connected to at least two wheels of the vehicle through mechanical means.

19. A powertrain according to claim 1, wherein the mechanical gear box has an output shaft, which is mechanically connected to two mechanical differentials, each differential driving at least two wheels of the vehicle.

20. A powertrain according to claim 1, wherein the mechanical gear box has an output shaft, which is connected to at least four wheels of the vehicle through mechanical means.

21. A powertrain according to claim 1, further comprising two tire side electric motors, each tire side electric motor being connected to at least one wheel of the vehicle.

22. A powertrain according to claim 1, further comprising two tire side electric motors, each tire side electric motor being connected to at least two wheels of the vehicle through a mechanical differential.

23. A powertrain according to claim 1, further comprising at least four tire side electric motors, each tire side electric motor being connected to at least one wheel.

24. A powertrain according to claim 1, further comprising at least two tire side electric motors, one tire side electric motor being mechanically connected to the output shaft of the mechanical gearbox and at least one tire side electric motor being connected to at least one wheel of the vehicle and being mechanically disconnected from the gearbox.

25. A powertrain according to claim 1, further comprising a device for disconnecting the at least one engine side electric motor from the output shaft of the at least one thermal engine.

26. A powertrain according to claim 25, further comprising a device for connecting the at least one engine side electric motor to an input shaft of the mechanical gearbox while the at least one engine side electric motor is disconnected from the output shaft of the at least one thermal engine.

27. A powertrain according to claim 1, further comprising a device or devices for disconnecting the at least one tire side electric motor from the wheels.

28. A powertrain according to claim 7, wherein a clutch is assembled on a rotor of the at least one engine side electric motor, in particular is assembled on the rotor in a manner similar to the manner in which clutches are assembled on flywheels of thermal engines.

29. A powertrain according to claim 1, wherein the mechanical gearbox has one input shaft and one output shaft.

30. A powertrain according to claim 1, wherein the mechanical gearbox has at least two input shafts and means to mechanically connect any one of the at least two input shafts to the at least one thermal engine and/or to the at least one engine side electric motor.

31. A powertrain according to claim 1, wherein the mechanical gearbox has at least two output shafts and means to mechanically connect any one of the at least two output shafts to at least one wheel of the vehicle.

32. A powertrain according to any claims 30-31, wherein the mechanical gearbox has two input shafts or two output shafts, cog wheels of the mechanical gearbox for even gear positions being located on a first one of the two shafts and cog wheels of the mechanical gearbox for odd gear positions being located on a second, different one of the two shafts, thus permitting an inactive shaft to synchronise a forthcoming gear position while another shaft transfers torque through the mechanical gearbox.

33. A powertrain according to claim 1, wherein the mechanical gearbox has means for manually shifting gear positions.

34. A powertrain according to claim 1, wherein the mechanical gearbox has means for manually shifting gear positions and means for performing automated gear shifts.

35. A powertrain according to claim 1, wherein the mechanical gearbox comprises an automatic transmission.

36. A powertrain according to claim 1, wherein the mechanical gearbox comprises means for manually shifting gear positing and means for indicate to a driver of the vehicle when a shift of gear position are likely to permit reduced losses.

37. A powertrain of a vehicle having wheels, the powertrain comprising

a mechanical gear box having an input shaft and an output shaft,

a mechanical differential having an input gear,

an electric energy supply,

an electric motor, which has a rotor, is mechanically connected to the input shaft of the gear box and is electrically connected to the energy supply and supplied with electric power from the energy supply for supplying or receiving mechanical power or torque when required,

the powertrain further comprising means connected directly or indirectly to at least two devices selected among:

the rotor of the electric motor,

the input shaft of the gear box,

the output shaft of the gear box,

the input gear of the differential,

for measuring the speed and/or the position of the devices to which the means are connected; and

means for adjusting a speed of the electric motor during an operation for shifting a gear position of the mechanical gearbox so that a speed of the input shaft of the mechanical gearbox is rapidly adjusted to a speed suitable for an engagement of forthcoming gear position of the mechanical gearbox.

38. A powertrain according to claim 37, further comprising means for adjusting during an operation for shifting a gear position of the mechanical gearbox a speed and position of the electric motor so that a speed and position of the input shaft of the mechanical gearbox relative to the output shaft of the mechanical gearbox is rapidly adjusted to values suitable for an engagement of a forthcoming gear position of the mechanical gearbox.

39. A powertrain according to any of claims 37 and 38, wherein the electric motor is mounted coaxially with the input shaft of the mechanical gear box and is connected to the input shaft of the mechanical gear box through a torsionally flexible coupling.

40. A powertrain according to claim 37, further comprising a device connected to the output shaft of the mechanical gearbox for creating a torque on the output shaft of the mechanical gearbox.

41. A powertrain according to claim 40, wherein the device connected to the output shaft of the mechanical gearbox is arranged to create a torque in both directions on the shaft.

42. A powertrain of a vehicle having wheels, the powertrain comprising

a thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels for carrying torque to and thereby driving the at least one of the wheels,

an energy storage,

an electric motor, which is mechanically connected to the thermal engine or to the at least one wheel and which is electrically connected to the energy storage and is supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

the powertrain further comprising torque measuring means connected to any of mechanical components carrying torque from the thermal engine to the at least one wheel,

wherein the torque measuring means is arranged to utilise torsional deflection of torsionally elastic elements in a mechanical path from the thermal engine to the at least one wheel;

further comprising means for estimating torque from the engine using values provided by the torque measuring means.

43. A powertrain according to claim 42 wherein said means for estimating torque also uses available information of torque of the electric motor.

44. A powertrain according to claim 42, wherein the torsionally elastic elements are arranged to provide a damping of ripple in torque from the thermal engine.

45. A powertrain according to claim 42, wherein the torsionally elastic elements are arranged to provide a considerable reduction of loads on synchronising components of the mechanical gearbox.

46. A method for selecting, in a powertrain of a vehicle having wheels, the powertrain comprising

a mechanical gear box,

at least one thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels through the mechanical gear box for driving the at least one of the wheels,

an energy storage,

at least one electric motor, which is connected to the energy storage and is supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

a gear position of the mechanical gearbox to be used, the method further comprising:

using desired values of torque to be provided by the at least one thermal engine and by the at least one electric motor, and

determining the desired values by the steps of;

selecting a set of operational points for each gear position, each point representing a set of desired values for the torque provided by the at least one thermal engine and the at least one electric motor, which set fulfils a total requirement of power to be provided to the at least one wheel as given by a driver of the vehicle,

noting those points which are within limitations of rate of change of a speed and torque of the thermal engine as set by exhaust pollution limitation criteria,

calculating losses in all components of powertrain,

selecting for a gear position which is currently in use, an operational point which gives lowest total losses,

selecting among all other gear positions that gear position the operational point of which gives lowest total losses,

calculating whether the improvement which can be obtained by a change of gear position is large enough to accept losses and inconvenience incurred due to change of gear position,

setting a next set of desired values for the gear positions and torque to be provided by the at least one thermal engine and the at least one electric motor in such a way that an optimum loss operational point can be reached after some time and in such a way that limitations of rate of change of the speed and torque of the at least one thermal engine as set by exhaust pollution limitation criteria are respected.

47. A method for selecting, in a powertrain of a vehicle having wheels, the powertrain comprising

a mechanical gear box,

at least one thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels through the mechanical gear box for driving the at least one of the wheels,

an energy storage,

at least one engine side electric motor and at least one tire side electric motor, which are connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required, a gear position of the mechanical gearbox to be used, the method further comprising:

using desired values of torque to be provided by the at least one thermal engine, by the at least one engine side electric motor and the at least one tire side electric motor, and

determining the desired values by the steps of;

selecting a set of operational points for each gear position, each point representing a set of desired values for the torque provided by the at least one thermal engine, the at least one engine side electric motor and the at least one tire side electric motor, which set fulfils a total requirement of power to be provided to the at least one wheel as given by the driver,

noting those points which are within limitations of rate of change of a speed and torque of the thermal engine as set by exhaust pollution limitation criteria,

calculating losses in all components of powertrain,

selecting for a gear position which is currently in use, an operational point which gives lowest total losses,

selecting among all other gear positions that gear position the operational point of which gives lowest total losses,

calculating if the improvement which can be obtained by a change of gear position is large enough to accept losses and inconvenience incurred due to change of gear position,

setting a next set of desired values for the gear positions and torque to be provided by the thermal engines, engine side electric motors and tire side electric motors in such a way that an optimum loss operational point can be reached after some time and in such a way that limitations of rate of change of the speed and torque of the at least one thermal engine as set by exhaust pollution limitation criteria are respected.

48. A method for controlling the decision to start or stop a thermal engine of a powertrain of a vehicle having wheels, the powertrain comprising

at least one thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels driving the at least one of the wheels,

an energy storage,

at least electric motor, which is mechanically connected to the engine or the at least one wheel and which is electrically connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

the method comprising:

having the engine started if the speed of the at least one of the wheels is above a first limit at the same time as the torque demanded for the at least one of the wheels is above a second limit,

having the engine switched off when the torque demand on the at least one of the wheels goes below a third limit,

the three limit values being changed as a function of the charge status of the energy storage, so that, when the charge status of the energy storage is low, the limit values are changed in a way which will cause the engine to be switched on earlier and switched off later, and when the charge status of the energy storage is high, the limit values are changed in a way which will cause the engine to be switched on later and switched off earlier.

49. A method according to claim 48, wherein in controlling the thermal engine signals are used which are derived from

indicating means by which a driver can indicate that a power burst that would cause a start of the engine is estimated by the driver to be of short duration, thus recommending a control system not to start the engine, and

estimating means by which the driver can indicate that the driver estimates that a considerable power burst will be required very soon, thus recommending the control system to start the engine.

51. A method according to any claims 48-50, further comprising recognising frequent driving patterns like when the driver seems to be on a frequent route like home-to-work and using the recognising in the controlling.

50. A method for controlling the decision to start or stop the thermal engine in a powertrain of a vehicle having wheels, the powertrain comprising

at least one thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels driving the at least one of the wheels,

an energy storage,

at least electric motor, which is mechanically connected to the engine or the at least one wheel and which is electrically connected to the energy storage and supplied with electric power from the energy storage for providing or receiving mechanical power or torque when required,

means to determine the position of the vehicle in relation to a data base over a road system,

the method comprising:

having the engine started if the torque demanded by the driver and the position of the vehicle in the road system indicates that the immediate and long term power requirement motivates a start of the engine,

having the engine stopped if the torque demanded by the driver and the position of the vehicle in the road system indicates that the immediate and long term power requirement motivates a stop of the engine,

a criteria used being changed as a function of the charge status of the energy storage, so that, when the charge status of the energy storage is low, the criteria being changed in a way which will cause the engine to be switched on earlier and switched off later, and when the charge status of the battery is high, the criteria being changed in a way which will cause the engine to be switched on later and switched off earlier.

52. A method according to claim 50, wherein the means to determine the position of the vehicle is a Global Position System device.

53. A powertrain of a vehicle having wheels, the powertrain comprising

at least one thermal engine having an output shaft,

an energy storage,

at least one engine side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the engine side electric motor to the output shaft of the thermal engine,

a mechanical gear box having an input shaft and an output shaft and at least three different gear ratios,

means for transferring torque from the output shaft of the gear box to at least one of the wheels,

at least one tire side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the tire side electric motor to the input shaft of the gear box, and

connection means connected to at least one selected among the at least one engine side electric motor and the output shaft of the at least one thermal engine and connected to at least one selected among the at least one tire side electric motor and the input shaft of the gear box for mechanically connecting the at least one thermal engine to the input shaft of the gear box.

54. The powertrain of claim 53, wherein the at least one tire side electric motor is rigidly connected to the input shaft of the gear box.

55. The powertrain of claim 53, wherein the mechanical gearbox comprises a manual type gearbox having automated, non-manual shifts of gear position.

56. The powertrain of claim 53, further comprising a torsionally flexible coupling, the at least one tire side electric motor mounted coaxially with the input shaft of the mechanical gear box and connected to the input shaft of the mechanical gear box through the torsionally flexible coupling, the torsionally flexible coupling connected in such a way that torque from the thermal engine must pass the torsionally flexible coupling when the thermal engine is mechanically connected to the at least one tire side motor.

57. The powertrain of claim 53, wherein the at least one tire side electric motor is assembled on the output shaft of the mechanical gear box.

58. The powertrain of claim 53, wherein the at least one engine side electric motor is coaxial with the output shaft of the at least one thermal engine.

59. The powertrain of claim 53, wherein the at least one engine side electric motor is arranged to supply or receive mechanical power or torque by being rigidly or directly coupled to the output shaft of the thermal engine.

60. The powertrain of claim 53 wherein the at least one engine side electric motor has a stator including electrically/magnetically active parts and a rotor including magnetically active parts, the magnetically active parts of the rotor being located radially outside, as seen from an axis of the motor, the electrically/magnetically active parts of the stator.

61. The powertrain of claim 53, further comprising at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and has a thermal capacity permitting the at least one device to operate as a clutch including a friction disc and a pressure plate.

62. The powertrain of claim 53, further comprising at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and has a limited thermal capacity permitting it to operate as a clutch including a friction disc and a pressure plate only for driving patterns adjusted to reduce the thermal load on the device.

63. The powertrain of claim 53, further comprising at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and is arranged in such a way that it can only perform the mechanical connection when a speed of an input shaft of the at least one device is close to a speed of an output shaft of the at least one device.

64. The powertrain of claim 53, further comprising at least one device which when required performs the mechanical connection between the at least one thermal engine and the at least one wheel and is adapted to only accept limited slip.

65. The powertrain of claim 53, wherein the at least one engine side electric motor has a power rating permitting the at least one engine side electric motor to absorb all power of the at least one thermal engine during gear shift operations of the mechanical gearbox even if torque and speed of the at least one thermal engine during a gear shift operation should be kept between optimal levels for a previous gear position and optimal levels for a forthcoming gear position.

66. The powertrain of claim 53, wherein the a least one engine side electric motor has a power rating permitting the at least one engine side electric motor to absorb all power of the at least one thermal engine during gear shift operations which are prolonged to permit slow changes in a speed of the at least one thermal engine.

67. The powertrain of claim 53, wherein the at least one engine side electric motor has a power rating permitting the at least one engine electric motor to continuously absorb all power of the at least one thermal engine for at least one speed and torque of the at least one thermal engine at which one speed and torque the at least one thermal engine can run at more than substantially 90% of a peak efficiency of the at least one thermal engine.

68. The powertrain of claim 53, further comprising a mechanical differential driving at least two of the wheels of the vehicle and mechanically connected to the output shaft of the mechanical gear box.

69. The powertrain of claim 53, further comprising mechanical means connecting the output shaft of the mechanical gear box to at least two of the wheels of the vehicle.

70. The powertrain of claim 53, further comprising two mechanical differentials, each of the two mechanical differentials driving at least two wheels of the vehicle and the output shaft of the mechanical gear box mechanically connected to each of the two mechanical differentials.

71. The powertrain of claim 53 further comprising mechanical means connecting the output shaft of the mechanical gear box to at least four of the wheels of the vehicle.

72. The powertrain of claim 53 comprising two tire side electric motors, each of the two tire side electric motors connected to at least one of the wheels of the vehicle.

73. The powertrain of claim 53 comprising two tire side electric motors and two mechanical differentials, each of the two tire side electric motors connected to at least two wheels of the vehicle through a respective one of the two mechanical differentials.

74. The powertrain of claim 53 comprising at least four tire side electric motors, each of the at least four tire side electric motors connected to at least one of the wheels of the vehicle.

75. The powertrain of claim 53 comprising at least two tire side electric motors, one of the two tire side electric motors mechanically connected to the output shaft of the mechanical gearbox and at least one of the two tire side electric motor connected to at least one of the wheels of the vehicle and mechanically disconnected from the gearbox.

76. The powertrain of claim 53, further comprising a device for disconnecting the at least one engine side electric motor from the output shaft of the at least one thermal engine.

77. The powertrain of claim 73, further comprising a device for connecting the at least one engine side electric motor to the input shaft of the mechanical gearbox while the at least one engine side electric motor is disconnected from the output shaft of the at least one thermal engine.

78. The powertrain of claim 53, further comprising at least one device for disconnecting the at least one tire side electric motor from the wheels of the vehicle.

79. The powertrain of claim 53, further comprising a clutch assembled on a rotor of the at least one engine side electric motor.

80. The powertrain of claim 79, wherein the clutch is assembled on the rotor in a manner similar to a manner in which clutches are assembled on flywheels of thermal engines.

81. The powertrain of claim 53, wherein the mechanical gearbox has a single input shaft and a single output shaft.

82. The powertrain of claim 53, wherein the mechanical gearbox comprises at least two input shafts and means to mechanically connect any one of the at least two input shafts to the at least one thermal engine and/or to the at least one engine side electric motor.

83. The powertrain of claim 53, wherein the mechanical gearbox comprises at least two output shafts and means to mechanically connect any one of the at least two output shafts to at least one of the wheels of the vehicle.

84. The powertrain of claim 53, wherein the mechanical gearbox comprises two input shafts or two output shafts, cog wheels of the mechanical gearbox for even gear positions being located on a first one of the two input or output shafts respectively and cog wheels of the mechanical gearbox for odd gear positions being located on a second, different one of the two input or output shafts, thereby permitting an inactive one of the two input or output shafts to synchronise a forthcoming gear position while another of the two input or output shafts transfers torque through the mechanical gearbox.

85. The powertrain of claim 53, wherein the mechanical gearbox comprises means for manually shifting gear positions.

86. The powertrain of claim 53, wherein the mechanical gearbox comprises means for manually shifting gear positions and means for performing automated gear shifts.

87. The powertrain of claim 53, wherein the mechanical gearbox comprises an automatic transmission.

88. The powertrain of claim 53, wherein the mechanical gearbox comprises means for manually shifting gear positions and means for indicating to a driver of the vehicle when a shift of gear position is likely to permit reduced losses.

89. The powertrain of claim 53, further comprising a first mechanical clutch connected in the output shaft of the thermal engine between a first portion of said output shaft close to the thermal engine and a second portion of said output shaft distant from the thermal engine, the at least one tire side electric motor mechanically connected to the second portion.

90. The powertrain of claim 89, wherein the at least one thermal engine side electric motor comprises a combined electric generator and motor mechanically connected to the first portion to be driven thereby and to drive the first portion, the combined electric motor and generator electrically connected to the energy storage to charge the energy storage and to be supplied with electric power thereby, when required.

91. The powertrain of claim 53, further comprising a differential gear, the output shaft of the mechanical gearbox having a cog wheel cooperating with a cog wheel on an input shaft of the differential gear, an output shaft of the least one tire side electric motor having a toothed wheel also co-operating with the toothed wheel of the input shaft of the differential gear.

92. The powertrain of claim 89, further comprising a second mechanical clutch connected in the output shaft of the thermal engine between the thermal engine and the combined electric generator and motor.

93. The powertrain of claim 53, further comprising measuring means connected directly or indirectly to at least two devices selected among:

the rotor of the electric motor,

the input shaft of the gear box,

the output shaft of the gear box,

the input gear of the differential,

for measuring the speed and/or the position of the devices to which the measuring means are connected.

94. The powertrain of claim 53, further comprising a torsionally flexible coupling, at least one of the at least one engine side electric motor and the at least one tire side electric motor being mounted coaxially with the input shaft of the mechanical gear box and connected to the input shaft of the mechanical gear box through the torsionally flexible coupling.

95. The powertrain of claim 53, further comprising a device connected to the output shaft of the mechanical gearbox for creating a torque on the output shaft of the mechanical gearbox, the created torque being relatively small and insignificant for propelling the vehicle.

96. The powertrain of claim 95, wherein the device connected to the output shaft of the mechanical gearbox is arranged to create a torque in both directions on the output shaft of the mechanical gearbox.

97. The powertrain of claim 53, further comprising torque measuring means connected to any of mechanical components carrying torque from the at least one thermal engine to at least one of the wheels of the vehicle.

98. The powertrain of claim 97, further comprising means for estimating torque from the at least one thermal engine using values provided by the torque measuring means.

99. The powertrain of claim 97, further comprising means for estimating torque from the thermal engine using values provided by the torque measuring means and using available information of torque of at least one of the at least one engine side electric motor and the at least one tire side electric motor.

100. The powertrain of claim 53, wherein at least part of filtered air from an air filter of the thermal engine is made to pass in such away that at least part of at least one of the at least one engine side electric motor and the at least one tire side electric motor obtains cooling from the filtered air.

101. The powertrain of claim 100, wherein at least part of the filtered air is made to pass through an airgap of said at least one of the at least one engine side electric motor and the at least one tire side electric motor.

102. The powertrain of claim 100, wherein at least part of the filtered air is made to pass along permanent magnets of said at least one of the at least one engine side electric motor and the at least one tire side electric motor.

103. The powertrain of claim 100, wherein at least part of the air is made to pass between windings of said at least one of the at least one engine side electric motor and the at least one tire side electric motor.

104. A powertrain of a vehicle having wheels, the powertrain comprising:

at least one thermal engine having an output shaft,

an energy storage,

at least one engine side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the engine side electric motor to the output shaft of the thermal engine,

a mechanical gear box having an input shaft and an output shaft,

means for transferring torque from the output shaft of the gear box to at least one of the wheels,

at least one tire side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the tire side electric motor to the input shaft of the gear box,

connection means connected to at least one selected among the at least one engine side electric motor and the output shaft of the at least one thermal engine and connected to at least one selected among the at least one tire side electric motor and the input shaft of the gear box for mechanically connecting the at least one thermal engine to the input shaft of the gear box; and

means for adjusting a speed of the electric motor during an operation for shifting a gear position of the mechanical gearbox so that a speed of the input shaft of the mechanical gearbox is rapidly adjusted to a speed suitable for a fast engagement of a forthcoming gear position of the mechanical gearbox.

105. A powertrain of a vehicle having wheels, the powertrain comprising:

at least one thermal engine having an output shaft,

an energy storage,

at least one engine side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the engine side electric motor to the output shaft of the thermal engine,

a mechanical gear box having an input shaft and an output shaft,

means for transferring torque from the output shaft of the gear box to at least one of the wheels,

at least one tire side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the tire side electric motor to the input shaft of the gear box,

connection means connected to at least one selected among the at least one engine side electric motor and the output shaft of the at least one thermal engine and connected to at least one selected among the at least one tire side electric motor and the input shaft of the gear box for mechanically connecting the at least one thermal engine to the input shaft of the gear box; and

means for adjusting during an operation for shifting a gear position of the mechanical gearbox a speed and position of the electric motor so that a speed and position of the input shaft of the mechanical gearbox relative to the output shaft of the mechanical gearbox is rapidly adjusted to values suitable for a fast engagement of a forthcoming gear position of the mechanical gearbox.

106. A powertrain of a vehicle having wheels, the powertrain comprising:

at least one thermal engine having an output shaft,

an energy storage,

at least one engine side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the engine side electric motor to the output shaft of the thermal engine,

a mechanical gear box having an input shaft and an output shaft,

means for transferring torque from the output shaft of the gear box to at least one of the wheels,

at least one tire side electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

mechanical means for transferring torque from the tire side electric motor to the input shaft of the gear box,

connection means connected to at least one selected among the at least one engine side electric motor and the output shaft of the at least one thermal engine and connected to at least one selected among the at least one tire side electric motor and the input shaft of the gear box for mechanically connecting the at least one thermal engine to the input shaft of the gear box; and

torque measuring means connected to any of mechanical components carrying torque from the at least one thermal engine to at least one of the wheels of the vehicle,

wherein the torque measurement means are arranged to utilise torsional deflection of at least one torsionally elastic element in a mechanical path from the at least one thermal engine to the at least one of the wheels of the vehicle.

107. The powertrain of claim 106, wherein the at least one torsionally elastic element is arranged to provide a damping of ripple in torque from the at least one thermal engine.

108. The powertrain of claim 106, further comprising at least one torsionally elastic element arranged to provide a considerable reduction of loads on synchronising components of the mechanical gearbox.

109. A method for selecting, in a powertrain of a vehicle having wheels, the powertrain comprising:

a mechanical gear box,

at least one thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels through the mechanical gear box for driving said at least one of the wheels,

an energy storage,

at least one electric motor connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

the method including the steps of;

using desired values of torque to be provided by the at least one thermal engine and by the at least one electric motor, and

determining the desired values by the steps of;

selecting a set of operational points for each gear position, each point representing a set of desired values for the torque provided by the at least one thermal engine and the at least one electric motor, which set fulfils a total requirement of power to be provided to the at least one wheel as given by a driver of the vehicle,

noting those points which are within limitations of rate of change of a speed and torque of the thermal engine as set by exhaust pollution limitation criteria,

calculating losses in all components of the powertrain for those operational points,

selecting for a gear position which is currently in use, an operational point which gives lowest total losses,

selecting among all other gear positions that gear position the operational point of which gives lowest total losses,

calculating whether an improvement which can be obtained by a change of gear position is large enough to accept losses and inconvenience incurred due to change of gear position,

setting a next set of desired values for the gear positions and torque to be provided by the at least one thermal engine and the at least one electric motor in such a way that an optimum loss operational point can be reached after some time and in such a way that limitations of rate of change of the speed and torque of the at least one thermal engine as set by exhaust pollution limitation criteria are respected.

110. The method of claim 109, wherein in the step of calculating, losses are calculated for thermal engines, engine side electric motors, tire side electric motors, electric power inverters and energy storage if any.

111. A method for selecting, in a powertrain of a vehicle having wheels, the powertrain comprising:

a mechanical gear box,

at least one thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels through the mechanical gear box for driving said at least one of the wheels,

an energy storage,

at least one engine side electric motor and at least one tire side electric motor, which are connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

a gear position of the mechanical gearbox to be used,

the method including the steps of;

using desired values of torque to be provided by the at least one thermal engine, by the at least one engine side electric motor and the at least one tire side electric motor, and

determining the desired values by the steps of;

selecting a set of operational points for each gear position, each point representing a set of desired values for the torque provided by the at least one thermal engine, the at least one engine side electric motor and the at least one tire side electric motor, which set fulfils a total requirement of power to be provided to the at least one wheel as given by the driver,

noting those points which are within limitations of rate of change of a speed and torque of the at least one thermal engine as set by exhaust pollution limitation criteria,

calculating losses in all components of powertrain for those operational points,

selecting for a gear position which is currently in use, an operational point which gives lowest total losses,

selecting among all other gear positions that gear position the operational point of which gives lowest total losses,

calculating if the improvement which can be obtained by a change of gear position is large enough to accept losses and inconvenience incurred due to change of gear position,

setting a next set of desired values for the gear positions and torque to be provided by the at least one thermal engine, the at least one engine side electric motor and the at least one tire side electric motor in such a way that an optimum loss operational point can be reached after some time and in such a way that limitations of rate of change of the speed and torque of the at least one thermal engine as set by exhaust pollution limitation criteria are respected.

112. The method of claim 111, wherein in the step of calculating, losses are calculated for thermal engines, engine side electric motors, tire side electric motors, electric power inverters and energy storage if any.

113. A method for controlling the decision to start or stop a thermal engine of a powertrain of a vehicle having wheels carrying tires, the powertrain comprising:

at least one thermal engine having an output shaft, which when required can be mechanically connected to at least one of the wheels for driving said at least one of the wheels,

an energy storage,

at least one electric motor, which is mechanically connected to the engine or said at least one wheel and which is electrically connected to the energy storage and supplied with electric power from the energy storage for supplying or receiving mechanical power or torque when required,

the method including the steps of;

having the engine started if the speed of the tires is above a first limit at the same time as the torque demanded for the tires is above a second limit,

having the engine switched off when the torque demand on the tires goes below a third limit

the three limit values being changed as a function of the charge status of the energy storage, so that, when the charge status of the energy storage is low, the limit values are changed in a way which will cause the engine to be switched on earlier and switched off later, and when the charge status of the energy storage is high, the limit values are changed in a way which will cause the engine to be switched on later and switched off earlier.

114. The method of claim 113, wherein, in controlling the at lest one thermal engine, signals are used which are derived from

first indicating means arranged to allow a driver of the vehicle to indicate, that a power burst that would cause a start of the at least one thermal engine, is estimated to be of short duration, thus recommending a control system not to start the at least one thermal engine, and

second indicating means arranged to allow the driver to indicate, that a considerable power burst is estimated to be required very soon, thus recommending the control system to start the at least one thermal engine.