SYSTEMS AND METHODS FOR SHIFT CONTROL FOR VEHICULAR TRANSMISSION

• US 20090018732A1
• Filed: 07/12/2007
• Published: 01/15/2009
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: Toyota Motor Corporation
• Original Assignee: Toyota Motor Corporation
• Inventors: Choby, Jordon, Mathis, Ken
• Granted Patent: US 8,370,032 B2
• Time in Patent Office: Days
• US Class Current: 701/51
• CPC Class Codes: F16H 2059/663 Road slope
• CPC Class Codes: F16H 2061/163 Holding the gear for delaying gear shifts under unfavorable conditions, e.g. during cornering
• 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 61/16 Inhibiting or initiating shift during unfavourable conditions, e.g. preventing forward reverse shift at high vehicle speed, preventing engine over speed unintentional control input F16H61/18

Abstract

Systems and methods for shift control for vehicular transmission. A transmission may shift gears at designated transmission shift points. When the slope of the road grade encountered by a vehicle changes, the transmission shift points may be altered to provide better vehicle performance. According to one embodiment, road slope may be calculated based upon vehicle acceleration and acceleration caused by pedal depression. In such an embodiment, brake indication may be calculated from the same road slope calculation without the use of a brake signal switch. If brake application is indicated by the road slope calculation, transmission shifting may be adjusted to prevent poor vehicle performance.

Claims

1. A method for controlling a vehicle transmission having gears and being configured to respond to at least one shift point for effectuating an automatic gear change, comprising:

calculating a road slope based upon one or more detected conditions during vehicle travel;

measuring a change in the calculated road slope;

detecting brake application based on the change in the calculated road slope; and

inhibiting a transmission gear change when brake application is detected.

2. The method as recited in claim 1, wherein the road slope calculation is based upon acceleration of the vehicle.

3. The method as recited in claim 1, wherein the road slope calculation is based upon accelerator pedal depression.

4. The method as recited in claim 1, wherein measuring change in the calculated road slope further includes comparing the calculated road slope with a reference road slope.

5. The method as recited in claim 4, wherein measuring change in the calculated road slope further includes compensating the reference road slope.

6. The method as recited in claim 5, wherein the reference road slope is representative of a flat road.

7. The method as recited in claim 5, wherein the reference road slope is compensated by an increasing step function.

8. The method as recited in claim 1, wherein brake application is detected if the change in the calculated road slope is greater than about 1.0 (% grade/s).

9. The method as recited in claim 1, wherein the operation of detecting brake application is accomplished without taking into account the status of a brake switch.

10. A method for determining vehicle braking, comprising:

detecting conditions during vehicle travel;

calculating a road slope based upon one or more detected conditions;

measuring a change in the calculated road slope;

comparing the change in the calculated road slope to a range of values representative of actual slope change encountered by a vehicle; and

indicating brake application when the change in the calculated road slope falls outside the range of values.

11. The method as recited in claim 10, wherein the road slope calculation is based upon acceleration of the vehicle.

12. The method as recited in claim 10, wherein the road slope calculation is based upon accelerator pedal depression.

13. The method as recited in claim 10, wherein measuring change in the calculated road slope further includes comparing the calculated road slope with a reference road slope.

14. The method as recited in claim 13, wherein measuring change in the calculated road slope further includes compensating the reference road slope.

15. The method as recited in claim 13, wherein the reference road slope is representative of a flat road.

16. The method as recited in claim 10, wherein the range of values is between 0.0% per second and 1.0% per second.

17. The method as recited in claim 10, wherein the operation of detecting brake application is accomplished without taking into account the status of a brake switch.

18. An vehicle braking indication system comprising:

vehicle condition sensors;

at least one processor operative to calculate a road slope from information systems and to indicate vehicle brake application based upon the calculated road slope; and

a transmission control system operative to inhibit a transmission gear change based upon the vehicle brake indication.

19. The system recited in claim 18, wherein the processor is operative to compare the calculated road slope with an reference road slope to indicate vehicle brake application.

20. The system recited in claim 18, wherein the processor is operative to adjust the reference road slope to indicate a flat road by applying an increasing step function.

21. The system recited in claim 18, wherein the vehicle sensors detect vehicle speed and accelerator pedal depression.