Driving force control system for vehicle

• US 9,630,610 B2
• Filed: 09/27/2011
• Issued: 04/25/2017
• Est. Priority Date: 09/27/2011
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Hayashi, Takeshi, Takeuchi, Keisuke, Agata, Yoshimitsu, Tanahashi, Toshio, Noumura, Shin, Tsuruoka, Kazuo, Kaneko, Hiroki, Honda, Tomoyuki
• Primary Examiner(s): Butler, Rodney
• Assistant Examiner(s): BRUSHABER, FREDERICK M
• Application Number:
  US14/347,346
• Publication Number:
  US 20150127200A1
• Time in Patent Office: 2,037 Days
• Field of Search: 701 22
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• 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 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/105 of electric type
• CPC Class Codes: B60W 10/11 Stepped gearings
• 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 20/30 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 2540/215 Selection or confirmation of options
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: B60W 50/082 Selecting or switching between different modes of propelling
• CPC Class Codes: F02D 2700/07 Automatic control systems according to one of the preceding groups in combination with control of the mechanism receiving the engine power
• CPC Class Codes: F02D 29/02 peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/84 Data processing systems or methods, management, administration

Abstract

A driving force control system for a vehicle having a mechanism for changing an engine speed continuously. The driving force control system basically controls said mechanism in a manner such that the engine speed is adjusted to optimize fuel economy. The driving force control system is configured to determine an index representing a demand to enhance agility of behavior of the vehicle based on an actual behavior of the vehicle or an amount of operation carried out by a driver to cause said behavior. An upper limit value of the engine speed of the case in which a drive demand is increased is determined on the basis of the index, and the upper limit value is set to the higher value with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

Claims

1. A driving force control system for a vehicle having a transmission mechanism for changing an engine speed continuously in accordance with a vehicle speed, comprising a control unit configured to:

control a speed ratio of the speed of the transmission mechanism on the basis of a vehicle speed and an opening degree of an accelerator;

determine an index representing a demand to enhance agility of behavior of the vehicle based on an acceleration of the vehicle;

change the index promptly in the direction to enhance the agility of the vehicle but relatively slower in the direction to moderate the behavior of the vehicle;

select a sporty mode if the index is larger than a threshold value; and

restrict the engine speed to an upper limit value that is lower than that to be achieved by a current speed ratio of the transmission when the acceleration is demanded, carry out an upshifting when the engine speed reaches the upper limit value of the current speed ratio, and set the upper limit value to a higher value with an increase in the index, in a case that the sporty mode is selected,

wherein the upper limit value is set in each stage of the speed ratio based on a maximum demanded acceleration rate which is a ratio of a demanded acceleration to a maximum possible acceleration of the vehicle that is calculated based on the index, and

wherein the upper limit value is set to a higher value with a reduction in the speed ratio.

2. The driving force control system for a vehicle as claimed in claim 1,

wherein the relation of the engine speed to the vehicle speed for the case of changing the engine speed by the transmission mechanism is determined in a manner such that the engine speed is increased in proportion to an increase in the vehicle speed from an original point;

and

a speed ratio as a relation of the engine speed to a vehicle speed is changed in accordance with the index and the vehicle speed in a manner such that the speed ratio is set to a larger ratio with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

3. The driving force control system for a vehicle as claimed in claim 2,

wherein the upper limit value of the engine speed is determined on the basis of the index;

the upper limit value is set to a higher value with an increase in the index representing the demand to enhance agility of behavior of the vehicle; and

the speed ratio is changed in accordance with the index, the vehicle speed and the upper limit value, in a manner such that the speed ratio is set to a larger ratio with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

4. The driving force control system for a vehicle as claimed in claim 3,

wherein a lower limit value of the engine speed is changed based on the index;

and

the lower limit value is set to a larger value with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

5. The driving force control system for a vehicle as claimed in claim 3, wherein the vehicle includes a hybrid vehicle in which said transmission mechanism is comprised of:

a power distribution device that is adapted to perform a differential action among an input element connected with the engine, a reaction element, and an output element, and

a motor that is connected with the reaction element, and that is adapted to change the engine speed thereby adjusting the engine speed to a target speed.

6. The driving force control system for a vehicle as claimed in claim 2,

wherein a lower limit value of the engine speed is changed based on the index;

and

the lower limit value is set to a larger value with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

7. The driving force control system for a vehicle as claimed in claim 2, wherein the vehicle includes a hybrid vehicle in which said transmission mechanism is comprised of:

a power distribution device that is adapted to perform a differential action among an input element connected with the engine, a reaction element, and an output element, and

a motor that is connected with the reaction element, and that is adapted to change the engine speed thereby adjusting the engine speed to a target speed.

8. The driving force control system for a vehicle as claimed in claim 1,

wherein a lower limit value of the engine speed is changed based on the index;

and

the lower limit value is set to a larger value with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

9. The driving force control system for a vehicle as claimed in claim 8, wherein the vehicle includes a hybrid vehicle in which said transmission mechanism is comprised of:

a power distribution device that is adapted to perform a differential action among an input element connected with the engine, a reaction element, and an output element, and

a motor that is connected with the reaction element, and that is adapted to change the engine speed thereby adjusting the engine speed to a target speed.

10. The driving force control system for a vehicle as claimed in claim 1,

wherein the engine speed is changed continuously in accordance with an opening degree of an accelerator and the vehicle speed until the index exceeds a threshold value, irrespective of a change in the index.

11. The driving force control system for a vehicle as claimed in claim 10, wherein the vehicle includes a hybrid vehicle in which said transmission mechanism is comprised of:

a power distribution device that is adapted to perform a differential action among an input element connected with the engine, a reaction element, and an output element, and

a motor that is connected with the reaction element, and that is adapted to change the engine speed thereby adjusting the engine speed to a target speed.

12. The driving force control system for a vehicle as claimed in claim 1, wherein the vehicle includes a hybrid vehicle in which said transmission mechanism is comprised of:

a power distribution device that is adapted to perform a differential action among an input element connected with the engine, a reaction element, and an output element, and

a motor that is connected with the reaction element, and that is adapted to change the engine speed thereby adjusting the engine speed to a target speed.

13. The driving force control system for a vehicle as claimed in claim 1,

wherein a lower limit value of the engine speed is changed based on the index;

and

the lower limit value is set to a larger value with an increase in the index representing the demand to enhance agility of behavior of the vehicle.

14. The driving force control system for a vehicle as claimed in claim 1, wherein the vehicle includes a hybrid vehicle in which said transmission mechanism is comprised of:

a power distribution device that is adapted to perform a differential action among an input element connected with the engine, a reaction element, and an output element, and

a motor that is connected with the reaction element, and that is adapted to change the engine speed thereby adjusting the engine speed to a target speed.