Method for controlling a drive system of a vehicle, a drive system, a computer program, a computer program product and a vehicle

• US 9,333,967 B2
• Filed: 06/26/2013
• Issued: 05/10/2016
• Est. Priority Date: 06/27/2012
• Status: Active Grant

• Current Assignee: Scania CV AB (Volkswagen AG)
• Original Assignee: Scania CV AB (Volkswagen AG)
• Inventors: Pettersson, Niklas, Bergquist, Mikael, Lindstrm, Johan, Kjell, Anders, Bjrkman, Mathias
• Primary Examiner(s): Chen, Shelley
• Application Number:
  US14/411,131
• Publication Number:
  US 20150239459A1
• Time in Patent Office: 1,049 Days
• Field of Search: 701/22
• US Class Current: 1/1
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60W 10/02 including control of driveline 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 10/115 with planetary gears
• CPC Class Codes: B60W 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements

Abstract

A method for controlling a drive system of a vehicle. The drive system includes a combustion engine (2) with an output shaft (2a), a gearbox (3) with an input shaft (3a), an electrical machine (9) that comprises a stator (9a) and a rotor (9b), and a planetary gear that comprises a sun gear (10), a ring gear (11) and a planet wheel carrier (12). If the torque from the combustion engine and the electrical machine is sufficient for the operation of the vehicle with the planetary gear in the released state, and if the fuel consumption of the vehicle with the planetary gear in the released state is lower than in the locked states, then control the electrical machine and the combustion engine so that the requested torque is provided while the planetary gear is in the released state. Otherwise the planetary gear is arranged in the locked state and the method is terminated.

Claims

1. A method for controlling a drive system of a vehicle, wherein the drive system comprises a combustion engine having an output shaft, a gearbox having an input shaft, an electrical machine comprising a stator and a rotor, and a planetary gear comprising three components comprising a sun gear, a ring gear and a planet wheel carrier;

connecting the output shaft of the combustion engine with a first one of the components of the planetary gear such that rotation of the output shaft causes rotation of the first component;

connecting the input shaft of the gearbox with a second one of the components of the planetary gear such that rotation of the input shaft causes rotation of the second component;

connecting the rotor of the electrical machine with a third one of the components of the planetary gear such that rotation of the rotor causes a rotation of the third component;

wherein the drive system further comprises locking means transferable between a locked state in which two of the components of the planetary gear are locked together for causing the three components to rotate with a same speed of rotation and a released state in which the three components are allowed to rotate with different respective speeds of rotation; and

the method comprising steps a)-d) of;

a) receiving information for a requested torque for operation of the vehicle, wherein the information comprises at least a first operation parameter of the combustion engine and at least a second operation parameter of the electrical machine,

b) determining whether an available torque from the combustion engine and from the electrical machine are sufficient for obtaining the requested torque with the planetary gear in the released state,

c) determining a fuel consumption of the vehicle with the planetary gear in the released state and in the locked state thereof based on the first and the second operation parameters,

d) if the torque from the combustion engine and the electrical machine is sufficient for obtaining the requested torque with the planetary gear in the released state, and if the fuel consumption of the vehicle with the planetary gear in the released state is lower than in the locked state, arranging or maintaining the planetary gear in the released state and controlling the electrical machine and the combustion engine so that the requested torque is provided while the planetary gear is in the released state, and otherwise arranging or maintaining the planetary gear in the locked state and terminating the method.

2. A method for controlling a drive system according to claim 1, further comprising:

initiating the method with the steps;

receiving information on a first operation parameter of the combustion engine and a second operation parameter of the electrical machine;

the step of determining the fuel consumption of the vehicle with the planetary gear in the released state and in the locked state thereof, based on the first and the second operation parameter; and

if the fuel consumption of the vehicle with the planetary gear in the released state is lower than in the locked state, arranging the planetary gear in the released state and performing the steps a)-d).

3. A method for controlling a drive system according to claim 1, further comprising controlling the electrical machine with regards to one of a torque and a speed of rotation thereof, and controlling the combustion engine with regards to the other of the torque and the speed of rotation.

4. A method for controlling a drive system according to claim 3, further comprising controlling the combustion engine such that the speed of rotation of the combustion engine is minimized with regards to a requested torque of the combustion engine.

5. A method for controlling a drive system according to claim 4, further comprising controlling the combustion engine to an idle speed of rotation.

6. A method for controlling a drive system according to claim 2, wherein the first operation parameter is a speed of rotation of the combustion engine.

7. A method for controlling a drive system according to claim 6, wherein the second operation parameter is a generated torque of the electrical machine.

8. A method for controlling a drive system according to claim 1, further comprising:

determining whether the torque from the combustion engine is sufficient for operation of the vehicle with the planetary gear in the released state based on generated torque from the combustion engine×

transmission ratio; and

determining whether the torque from the electrical machine is sufficient for operation of the vehicle with the planetary gear in the released state based on generated torque from the electrical machine×

1−

transmission ratio, where the transmission ratio is a ratio between a number of teeth of the sun gear and a number of teeth of the ring gear+a number of teeth of the sun gear.

9. A method for controlling a drive system according to claim 1, wherein the gearbox comprises at least a first gear with a first lowest torque, and a second gear with a second lowest torque, and a third gear with a third lowest torque, wherein the first lowest torque is lower than the second lowest torque and the second lowest torque is lower than the third lowest torque,

the method further comprising:

arranging or maintaining the planetary gear in the released state while the gearbox is arranged in the first gear;

increasing the torque of the drive system from at least the second lowest torque to at least the third lowest torque by controlling the combustion engine and the electrical machine while maintaining a speed of rotation of the combustion engine;

changing gear of the gearbox from the first gear to the third gear; and

arranging the planetary gear in the locked state and then terminating the method.

10. A method for controlling a drive system according to claim 1, wherein in the locked state, the locking means is configured to connect the ring gear and the planet wheel carrier to rotate together;

and

a change from the locked state to the released state comprises;

controlling the electrical machine and the combustion engine to a condition mutually free of torque, and

releasing the locking means from engagement with the ring gear and the planet wheel carrier so that the ring gear and the planet wheel carrier are freely rotatable in relation to each other.

11. A method for controlling a drive system according to claim 10, wherein the locking means in the locked state is configured to connect the ring gear and the planet wheel carrier so that they rotate together;

and

a change from the released state to the locked state comprises;

controlling the electrical machine and the combustion engine to a condition mutually free of torque, and

displacing the locking means from engagement with the ring gear and the planet wheel carrier.

12. A method for controlling a drive system according to claim 1, wherein

the output shaft of the combustion engine is connected with the sun gear so that they rotate as a unit with a first speed of rotation (n₁);

the input shaft of the gearbox is connected with the planet wheel carrier so that they rotate as a unit with a second speed of rotation (n₂); and

the rotor of the electrical machine is connected with the ring gear so that the ring gear rotates with a third speed of rotation (n₃).

16. A computer program product comprising a non-volatile data storage medium that is readable by a computer, and a computer program stored therein, wherein the program comprises computer program code operable to implement a method according to claim 1 when the program code is executed in the computer.

13. A drive system for a vehicle, the drive system comprising:

a combustion engine with an output shaft;

a gearbox with an input shaft;

an electrical machine comprising a stator and a rotor;

a planetary gear comprising three components in the form of a sun gear, a ring gear and a planet wheel carrier;

the output shaft of the combustion engine is connected with a first one of the components of the planetary gear so that a rotation of the output shaft causes a rotation of the first component,

the input shaft of the gearbox is connected with a second one of the components of the planetary gear so that a rotation of the input shaft causes a rotation of the second component;

the rotor of the electrical machine is connected with a third one of the components of the planetary gear so that rotation of the rotor causes a rotation of the component,

the drive system further comprises locking means transferable between a locked state in which two of the components are locked together so that the three components rotate with the same speed of rotation and a released state in which the components are allowed to rotate with different respective speeds of rotation;

the drive system comprises a control unit configured to receive information about a torque demanded to drive the vehicle;

at least a first operation parameter of the combustion engine and at least a second operation parameter of the electric machine, configured for determining whether the available torque from the combustion engine and the electric machine is sufficient to reach the demanded torque with the planetary gear in the released state, and to determine the fuel consumption of the vehicle with the planetary gear in the released state and in the locked state based on the first and the second operation parameter;

if the torque from the combustion engine and the electrical machine is sufficient for the operation of the vehicle with the planetary gear in the released state, and if the fuel consumption of the vehicle with the planetary gear in the released state is lower than in the locked state, adjusting the control unit further to arrange or maintain the planetary gear in the released state and to control the electrical machine and the combustion engine so that the requested torque is provided while the planetary gear is in the released state and while maintaining the speed of rotation of the combustion engine.

14. A drive system for a vehicle according to claim 13, further comprising means for controlling the speed of rotation of the combustion engine.

15. A drive system for a vehicle according to claim 13, wherein the drive system comprises means for controlling the torque of the electrical machine.

17. A vehicle comprising a drive system according to claim 13.