Vehicle and Method of Control Thereof

• US 20150314771A1
• Filed: 12/10/2013
• Published: 11/05/2015
• Est. Priority Date: 12/10/2012
• Status: Active Grant

• Current Assignee: Jaguar Land Rover Limited (TATA Motors Limited)
• Original Assignee: Jaguar Land Rover Limited (TATA Motors Limited)
• Inventors: Dextreit, Clement, Ellis, Mark, Hancock, Matt
• Granted Patent: US 9,725,083 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/48 Parallel type
• 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2554/00 Input parameters relating to objects
• CPC Class Codes: B60W 2554/406 Traffic density
• CPC Class Codes: B60W 2554/801 Lateral distance
• CPC Class Codes: B60W 2554/804 Relative longitudinal speed
• CPC Class Codes: B60W 2556/45 External transmission of data to or from the vehicle
• CPC Class Codes: B60W 2710/06 Combustion engines, Gas turbines
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/16 Control of distance between vehicles, e.g. keeping a distance to preceding vehicle
• CPC Class Codes: B60W 50/082 Selecting or switching between different modes of propelling
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements

Abstract

The invention provides a speed control system and method for a hybrid electric vehicle, the vehicle having an engine (121), an electric machine (123) and a mode switch (169), to allow switching between a first speed control mode (EV) and a second speed control mode (HEV). When the control system is in the first mode and at least one of a prescribed one or more conditions is met, e.g. a rate of acceleration demanded by the driver or a difference between a target vehicle speed and a current vehicle speed exceeds a respective prescribed threshold value, the system is operable to not limit operation of the vehicle to the EV mode.

Claims

1. A speed control system for a hybrid electric vehicle, the vehicle having at least one engine and at least one electric machine, the system being operable to allow a driver to set a target vehicle speed, the system being operable in first and second speed control modes to control the vehicle to maintain the target vehicle speed, wherein in the first speed control mode the system is configured to limit operation of the vehicle to an electric vehicle (EV) mode, wherein in the second speed control mode the system is configured not to limit operation of the vehicle to the EV mode, and wherein when the control system is in the first speed control mode and at least one of a prescribed one or more conditions is met, the system is operable to not limit operation of the vehicle to the EV mode.

2. The speed control system of claim 1, further operable to maintain a prescribed distance behind a followed vehicle at a speed not exceeding the target vehicle speed.

3. The speed control system of claim 2, further operable to determine a required rate of acceleration of the vehicle in order to maintain the prescribed distance behind the followed vehicle, the system being operable in the first speed control mode to limit operation of the vehicle to the EV mode by limiting a maximum rate of acceleration that may be commanded by the system to a rate that is achievable in EV mode.

4. The speed control system of claim 3, further operable in the first speed control mode to limit the maximum rate of acceleration that may be commanded by the system to a rate corresponding substantially to the maximum rate achievable in EV mode.

5. The speed control system of claim 1, further operable in the first speed control mode to limit operation of the vehicle to the EV mode by limiting a maximum amount of drive torque that may be commanded by the system to an amount that is achievable in EV mode.

6. The speed control system of claim 5, further operable in the first speed control mode to limit the maximum amount of drive torque that may be commanded by the system to a rate corresponding substantially to the maximum amount achievable in EV mode.

7. The speed control system of claim 1, wherein the prescribed one or more conditions includes a condition that a difference between the target vehicle speed and a current vehicle speed exceeds a prescribed delta speed value.

8. The speed control system of claim 7, wherein the prescribed delta speed value is determined in dependence on gradient of a surface over which the vehicle is driving.

9. The speed control system of claim 7, wherein the said prescribed one or more conditions includes the condition that a difference between the target vehicle speed and a current vehicle speed exceeds the prescribed delta speed value and a followed vehicle is accelerating at a rate exceeding a prescribed followed vehicle acceleration rate.

10. The speed control system of claim 9, wherein the prescribed followed vehicle acceleration rate is determined in dependence on gradient of a surface over which the vehicle is driving.

11. The speed control system of claim 9, wherein the prescribed followed vehicle acceleration rate corresponds substantially to the maximum rate of acceleration that the system is permitted to command when the system is operating in the first speed control mode and none of the prescribed one or more conditions is met.

12. The speed control system of claim 1, wherein the prescribed one or more conditions includes a condition that the driver demands a rate of acceleration of the vehicle which exceeds a prescribed threshold value.

13. The speed control system of claim 1, wherein the prescribed one or more conditions includes a condition that the driver demands an amount of drive torque which exceeds a prescribed threshold value.

14. The speed control system of claim 1, further operable automatically to assume the second speed control mode if whilst in the first speed control mode, the at least one engine is started more than a prescribed number of times within a prescribed period of time.

15. The speed control system of claim 1, further operable automatically to assume the second speed control mode if whilst in the first speed control mode, it is determined that a density of traffic exceeds a prescribed value.

16. The speed control system of claim 15, further operable to determine the density of traffic responsive to traffic density data received by the system from a traffic information service.

17. The speed control system of claim 15, further operable to determine the density of traffic responsive to measurement of a number of vehicles passing the vehicle within a prescribed period of time.

18. The speed control system claim 15, further operable to determine the density of traffic responsive to measurement of a number of vehicles passed by the vehicle within a prescribed period of time.

19. The speed control system of claim 1, further operable automatically to assume the second speed control mode if, whilst in the first speed control mode, the driver increases a rate of acceleration of the vehicle above a maximum value available in EV mode, one or more times in a given time period, a prescribed number of times over a given distance and/or a prescribed number of times over a given journey.

20. The speed control system of claim 1, wherein the prescribed one or more conditions includes a condition that a maximum rate of acceleration achievable by the vehicle in EV mode is below a prescribed threshold value.

21. The speed control system of claim 1, wherein the prescribed one or more conditions includes a condition that a maximum amount of torque achievable by the vehicle in EV mode is below a prescribed threshold value.

22. The speed control system of claim 1, further comprising a driver-operable control to select one of the first and second speed control modes.

23. The speed control system of claim 1, further operable to store data in respect of geographical locations at which an engine start has been commanded by the system, when the vehicle subsequently approaches the same location in substantially the same direction of travel the system being configured to start the at least one engine in advance of arrival at the location such that power generated as a consequence of starting the at least one engine may be delivered to a driveline of the vehicle substantially at said location.

24. The speed control system of claim 23, further configured to start the at least one engine in advance of arrival at the location such that drive torque from the engine may be delivered to the driveline of the vehicle substantially at said location.

25. The speed control system of claim 23, further configured to store said data in respect of geographical location only when the at least one engine was started in the absence of driver intervention causing an engine start such as accelerator pedal actuation.

26. The speed control system of claim 23, further configured to store said data in respect of geographical location only when the at least one engine was started when the traffic density was below a threshold value.

27. The speed control system of claim 23, further configured to store said data in respect of geographical location only when a followed vehicle was not accelerating at a rate exceeding a prescribed rate thereby triggering an engine start.

28. The speed control system of claim 23, further configured to store said data in respect of geographical location only when the at least one engine was started (1) not in response to driver intervention causing an engine start such as accelerator pedal actuation, (2) when traffic density was below a threshold value and (3) when a followed vehicle was not accelerating at a rate exceeding a prescribed rate thereby triggering an engine start.

29. A hybrid electric vehicle comprising the speed control system of claim 1.

30. A method of controlling speed of a hybrid electric vehicle via a speed control system, the method comprising:

allowing a driver to set a target vehicle speed;

controlling the vehicle to maintain the target speed;

in a first speed control mode of the control system, limiting operation of the vehicle to an electric vehicle (EV) mode;

in a second speed control mode of the control system, not limiting operation of the vehicle to the EV mode;

wherein when the speed control system is in the first speed control mode and at least one of a prescribed one or more conditions is met, not limiting operation of the vehicle to the EV mode.

31. (canceled)