Systems and methods for controlling transmission shifting during vehicle braking along a decline

• US 7,853,385 B2
• Filed: 08/10/2007
• Issued: 12/14/2010
• Est. Priority Date: 08/10/2007
• Status: Active Grant

• Current Assignee: Toyota Motor Corporation
• Original Assignee: Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Ly, Tai Joey
• Primary Examiner(s): Nguyen; Cuong H
• Application Number:
  US11/891,432
• Publication Number:
  US 20090043463A1
• Time in Patent Office: 1,222 Days
• Field of Search: 701/51, 701 55- 56, 180/337, 477/34
• US Class Current: 701/51
• CPC Class Codes: F16H 59/54 dependent on signals from the brakes, e.g. parking brakes
• CPC Class Codes: F16H 59/66 Road conditions, e.g. slope, slippery
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/21 Providing engine brake control

Abstract

In some embodiments, systems and methods are provided for controlling transmission downshifting of a vehicle. The systems and methods monitor vehicular conditions continuously throughout vehicle travel such that downshifting may occur during braking along a decline and are not influenced by and do not interfere with road grade calculation systems. In one embodiment, a system comprises sensors that monitor vehicular conditions. The sensors transmit signals indicative of vehicular conditions to an electronic controller that processes the signals. The electronic controller generates instructions for downshifting where the processed signals indicate vehicle travel along a decline and when downshifting would not cause exceeding of a maximum revolutions per minute limit. The instructions are transmitted to a transmission system that downshifts the transmission gear position according to the instructions. The electronic controller cancels the instructions for the downshifting when the degree or duration of accelerator pedal depression exceed predefined values.

Claims

1. A method of controlling transmission downshifting of a vehicle, the method comprising:

monitoring various vehicular conditions during vehicle travel;

transmitting signals indicative of the vehicular conditions;

processing the transmitted signals;

generating instructions for a downshifting of a transmission gear position of a transmission system of the vehicle when the processed signals indicate vehicle travel along a declining road grade, when braking is being applied by a brake, and when downshifting would not cause a predefined limit of a vehicular condition to be exceeded;

transmitting the instructions for the downshifting to the transmission system; and

downshifting the transmission gear position according to the instructions,

wherein the instructions for the downshifting are canceled when at least one of one or more accelerator conditions achieve a predefined value.

2. The method of claim 1, wherein the method of controlling transmission downshifting is not influenced by and does not interfere with any road grade calculation systems of the vehicle.

3. The method of claim 1, wherein the monitoring of the vehicular conditions is performed continuously throughout vehicle travel such that downshifting occurs during vehicle braking along the declining road grade.

4. The method of claim 1, wherein the vehicular conditions comprise:

engine rotational velocity;

transmission gear position;

at least one of degree of accelerator pedal depression and duration of accelerator pedal depression; and

at least one of;

a. duration of brake pedal depression;

b. degree of brake pedal depression;

c. brake pressure;

d. increase in speed of the vehicle without depressions of brake pedal and acceleration pedal;

e. frequency of accelerator pedal depression;

f. G characteristic of vehicle;

g. frequency of steering wheel adjustments; and

h. estimation of engine rotational velocity at next lower transmission gear position.

5. The method of claim 4, wherein the one or more accelerator conditions that cancel the instructions for the downshifting are the degree of accelerator pedal depression and the duration of accelerator pedal depression.

6. The method of claim 5, wherein the electronic controller is configured such that the instructions for the downshifting are canceled when the degree of accelerator pedal depression is between 1 degree and 84 degrees or the duration of accelerator pedal depression is between 0.1 seconds and 10 seconds.

7. A system for controlling transmission downshifting of a vehicle, the system comprising:

one or more sensors configured to monitor vehicular conditions indicative of vehicle travel, wherein the sensors are configured to transmit signals indicative of the vehicular conditions;

an electronic controller configured to process the signals, wherein the electronic controller is configured to generate instructions for a downshifting of a transmission gear position of a transmission system of the vehicle when the processed signals indicate vehicle travel along a declining road grade and when the processed signals comport with predefined limits at vehicular conditions where downshifting is permitted; and

circuitry for transmitting the signals to the electronic controller and for transmitting the instructions to a transmission system of the vehicle, wherein the transmission system is configured to downshift the transmission gear position according to the instructions,

wherein the sensors are configured to monitor the vehicular conditions continuously throughout vehicle travel such that downshifting occurs during vehicle braking along the declining road grade.

8. The system of claim 7, wherein the electronic controller comprises an electronic control unit.

9. The system of claim 7, wherein the system is not influenced by and does not interfere with any road grade calculation systems of the vehicle.

10. The system of claim 7, wherein the sensors of the system comprise:

a tachometer;

a transmission gear position sensor;

an accelerator sensor; and

at least one of;

a. a brake sensor;

b. an acceleration sensor;

c. a vehicle G characteristic sensor; and

d. a steering wheel sensor.

11. The system of claim 10, wherein:

a. the tachometer is configured to monitor the vehicular condition of engine rotational velocity;

b. the transmission gear position sensor is configured to monitor the vehicular conditions of transmission gear position and estimation of engine rotational velocity at next lower transmission gear position;

c. the brake sensor is configured to monitor the vehicular conditions of degree of brake pedal depression, duration of brake pedal depression, and brake pressure;

d. the accelerator sensor is configured to monitor the vehicular conditions of degree of accelerator pedal depression, duration of accelerator pedal depression, and frequency of accelerator pedal depression;

e. the acceleration sensor is configured to monitor the vehicular condition of increases in speed of the vehicle without depressions of brake pedal or accelerator pedal;

f. the vehicle G characteristic sensor is configured to monitor the vehicular condition of a G characteristic of the vehicle; and

g. the vehicle steering sensor is configured to monitor the vehicular condition of frequency of steering wheel adjustment.

12. The system of claim 7, wherein the electronic controller is configured such that the instructions for the downshifting are canceled when at least one of one or more accelerator conditions achieve a predefined value.

13. The system of claim 12, wherein the one or more accelerator conditions that cancel the instructions for the downshifting are the degree of accelerator pedal depression and the duration of accelerator pedal depression.

14. The system of claim 13, wherein the predefined value for the degree of accelerator depression sufficient to cancel the instructions for downshifting is between 1 degree and 84 degrees.

15. The system of claim 13, wherein the predefined value for the duration of accelerator depression sufficient to cancel the instructions for downshifting is between 0.1 seconds and 10 seconds.

16. The system of claim 7, wherein the predefined limits of vehicular conditions represent relationships between each transmission gear position of the transmission system and partially overlapping ranges of engine revolutions per minute of engine rotational velocity.

17. The system of claim 16, wherein the predefined limits of vehicular conditions that permit downshifting are defined such that downshifting is not permitted if engine revolutions per minute of the monitored engine rotational velocity would exceed upper limits of the range of engine revolutions per minute associated with the transmission gear position lower than the current transmission gear position.

18. A vehicle comprising a system for controlling transmission downshifting of a vehicle, wherein the system comprises:

one or more sensors configured to monitor vehicular conditions indicative of vehicle travel, wherein the sensors are configured to transmit signals indicative of the vehicular conditions;

an electronic controller configured to process the signals, wherein the electronic controller is configured to generate instructions for a downshifting of a transmission gear position of a transmission system of the vehicle when the processed signals indicate vehicle travel along a declining road grade and when the processed signals comport with predefined limits of vehicular conditions that permit downshifting; and

circuitry configured to transmit the signals to the electronic controller and to transmit the instructions to a transmission system of the vehicle, such that the transmission system downshifts the transmission gear position according to the instructions,

wherein the sensors are configured to monitor the vehicular conditions continuously throughout vehicle travel such that downshifting occurs during vehicle braking along the declining road grade,

wherein the system is not influenced by and does not interfere with any road grade calculation systems of the vehicle.

19. The vehicle of claim 18, wherein the sensors of the system comprise:

a tachometer;

a transmission gear position sensor;

an accelerator sensor; and

at least one of;

a. a brake sensor;

b. an acceleration sensor;

c. a vehicle G characteristic sensor; and

d. a steering wheel sensor.

20. The vehicle of claim 18, wherein the electronic controller is configured such that the instructions for the downshifting are canceled when the degree of accelerator pedal depression is between 1 degree and 84 degrees or the duration of accelerator pedal depression is between 0.1 seconds and 10 seconds.