Control system and method for vehicle having continuously variable transmission

• US 20030022753A1
• Filed: 07/22/2002
• Published: 01/30/2003
• Est. Priority Date: 07/26/2001
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Mizuno, Makoto, Mogi, Kazuhisa
• Granted Patent: US 6,726,594 B2
• Time in Patent Office: Days
• US Class Current: 477/43
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: F16H 2302/02 Optimizing the way to the new ratio
• CPC Class Codes: F16H 2306/30 characterised by the way or trajectory to a new ratio, e.g. by performing shift according to a particular algorithm or function determining the way or trajectory to a new ratio F16H2302/00
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38

Abstract

A control system for a vehicle in which an internal combustion engine whose output torque is controlled based on a required output power is coupled to a continuously variable transmission whose input rotation speed is controlled based on the required output power. A controller of the system determines a final target operating point of the engine which is defined by the output torque and the input rotation speed, on the basis of the required output power, and sets a transient operating point to one of possible operating points that can be achieved within a predetermined period of time such that the operating point of the engine approaches the final target operating point. The controller then controls the output torque and the input rotation speed of the continuously variable transmission so as to operate the engine at the set transient operating point.

Claims

1. A control system for a vehicle in which an internal combustion engine whose output torque is controlled based on a required output power is coupled to a continuously variable transmission whose input rotation speed is controlled based on the required output power, comprising a controller that:

determines a final target operating point of the internal combustion engine which is defined by the output torque and the input rotation speed, on the basis of the required output power;

sets a transient operating point of the engine to one of possible operating points that can be achieved within a predetermined period of time such that the transient operating point is closer to the final target operating point than the current operating point of the engine; and

controls the output torque and the input rotation speed of the continuously variable transmission so as to operate the internal combustion engine at the set transient operating point.

2. The control system according to claim 1, wherein:

the internal combustion engine includes a turbocharger; and

the controller sets the transient operating point on the basis of a delay in an increase in a boost pressure of the turbocharger and a delay in a change of a speed ratio of the continuously variable transmission.

3. The control system according to claim 1, wherein the controller sets the transient operating point on the basis of a delay in a change of a speed ratio of the continuously variable transmission.

4. The control system according to claim 1, wherein the controller sets the transient operating point to one of possible operating points which is reached when the largest amounts of changes occur in the output torque and the input rotation speed within the predetermined period of time.

5. The control system according to claim 2, wherein the controller sets the transient operating point to one of possible operating points which is reached when the largest amounts of changes occur in the output torque and the input rotation speed within the predetermined period of time.

6. The control system according to claim 1, wherein the controller sets the transient operating point to one of possible operating points which is closest to the final target operating point.

7. The control system according to claim 2, wherein the controller sets the transient operating point to one of possible operating points which is closest to the final target operating point.

8. The control system according to claim 1, wherein the possible operating points are determined based on the output torque and the input rotation speed that can be achieved within the predetermined period of time.

9. A method of controlling a vehicle in which an internal combustion engine whose output torque is controlled based on a required output power is coupled to a continuously variable transmission whose input rotation speed is controlled based on the required output power, comprising the steps of:

determining a final target operating point of the internal combustion engine which is defined by the output torque and the input rotation speed, on the basis of the required output power;

setting a transient operating point of the engine to one of possible operating points that can be achieved within a predetermined period of time such that the transient operating point is closer to the final target operating point than the current operating point of the engine; and

controlling the output torque and the input rotation speed of the continuously variable transmission so as to operate the internal combustion engine at the set transient operating point.

10. The method according to claim 9, wherein:

the internal combustion engine includes a turbocharger; and

the transient operating point is set on the basis of a delay in an increase in a boost pressure of the turbocharger and a delay in a change of a speed ratio of the continuously variable transmission.

11. The method according to claim 9, wherein the transient operating point is set on the basis of a delay in a change of a speed ratio of the continuously variable transmission.

12. The method according to claim 9, wherein the transient operating point is set to one of possible operating points which is reached when the largest amounts of changes occur in the output torque and the input rotation speed within the predetermined period of time.

13. The method according to claim 10, wherein the transient operating point is set to one of possible operating points which is reached when the largest amounts of changes occur in the output torque and the input rotation speed within the predetermined period of time.

14. The method according to claim 9, wherein the transient operating point is set to one of possible operating points which is closest to the final target operating point.

15. The method according to claim 10, wherein the transient operating point is set to one of possible operating points which is closest to the final target operating point.

16. The method according to claim 9, wherein the possible operating points are determined based on the output torque and the input rotation speed that can be achieved within the predetermined period of time.