WIDE OPEN THROTTLE GUARD FOR A VEHICLE FOR HIGH ELEVATION CHANGES

• US 20150039192A1
• Filed: 07/30/2013
• Published: 02/05/2015
• Est. Priority Date: 07/30/2013
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Gauthier, Christopher T.
• Granted Patent: US 9,073,533 B2
• Time in Patent Office: Days
• US Class Current: 701/54
• 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 2510/0619 Air-fuel ratio
• CPC Class Codes: B60W 2552/25 Road altitude
• CPC Class Codes: F16H 2059/366 Engine or motor speed
• CPC Class Codes: F16H 2061/0234 Adapting the ratios to special vehicle conditions
• CPC Class Codes: F16H 59/34 dependent on fuel feed
• CPC Class Codes: F16H 59/60 Inputs being a function of ambient conditions
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals

Abstract

A system for improving performance of a hybrid vehicle at higher elevations. The system includes a plurality of wheels, an engine, an altitude sensor, a transmission, a memory for storing target engine speeds, and a processor. The engine provides a torque to the plurality of wheels through the transmission, based on gear ratios limited by a wide open throttle (WOT) guard. The altitude sensor determines an elevation of the vehicle. Above a certain threshold elevation, the processor changes the WOT guard to improve performance at lower gears, such as standing start performance.

Claims

1. A system for controlling a transmission of a vehicle comprising:

a transmission capable of shifting gear ratios;

an engine connected to the transmission and having an engine speed and an engine power;

an altitude sensor for detecting an altitude of the vehicle;

a memory for storing a gear ratio limit based on the engine speed and the engine power, and a predetermined altitude corresponding to an altitude above which an engine performance of the engine is reduced; and

a processor configured to receive the altitude and adjust the gear ratio limit based on the altitude when the altitude exceeds the predetermined altitude.

2. The system of claim 1, wherein the processor adjusts the gear ratio limit by lowering the gear ratio limit such that the transmission can hold a low gear for a longer period of time.

3. The system of claim 1, wherein the memory stores the gear ratio limit in a table with gear ratio limit values, engine speed values and engine power values.

4. The system of claim 3, wherein the processor adjusts the gear ratio limit by adjusting the gear ratio limit values and the engine power values.

5. The system of claim 1, wherein the processor continuously adjusts the gear ratio limit.

6. The system of claim 1, wherein the processor dynamically calculates the predetermined altitude.

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

a transmission capable of shifting gear ratios;

an engine connected to the transmission and having an engine speed, an engine power, and an air-fuel ratio;

a sensor for detecting the air-fuel ratio;

a memory for storing a gear ratio limit based on the engine speed and the engine power, and an air-fuel ratio threshold which corresponds to an air-fuel ratio value below which an engine performance of the engine is reduced; and

a processor configured to receive the air-fuel ratio and adjust the gear ratio limit based on the air-fuel ratio when the air-fuel ratio reaches the air-fuel ratio threshold.

8. The system of claim 7, wherein the processor adjusts the gear ratio limit by lowering the gear ratio limit such that the transmission can hold a low gear for a longer period of time.

9. The system of claim 7, wherein the memory stores the gear ratio limit in a table with gear ratio limit values, engine speed values and engine power values.

10. The system of claim 9, wherein the processor adjusts the gear ratio limit by adjusting the gear ratio limit values and the engine power values.

11. The system of claim 7, wherein the processor continuously adjusts the gear ratio limit.

12. The system of claim 7, wherein the processor dynamically calculates the air-fuel ratio threshold.

13. A method for controlling a transmission of a vehicle comprising:

providing a memory for storing a gear ratio limit for limiting a transmission of the vehicle based on an engine speed and an engine power of an engine of the vehicle;

receiving a sensor value from a sensor of the vehicle;

comparing the sensor value to a sensor value threshold stored in the memory, the sensor value threshold corresponding to a reduction in an engine performance of the engine; and

adjusting a gear ratio limit based on the sensor value when the sensor value threshold is reached.

14. The method of claim 13, wherein the sensor is an altitude sensor and the sensor value is an altitude of the vehicle.

15. The method of claim 13, wherein the sensor is an air-fuel ratio sensor and the sensor value is an air-fuel ratio of the engine.

16. The method of claim 13, wherein adjusting the gear ratio limit further comprises lowering the gear ratio limit, such that a low gear can be held for a longer period of time.

17. The method of claim 13, wherein the memory stores the gear ratio limit in a table of gear ratio limit values, engine speed values and engine power values, and adjusting the gear ratio limit further comprises adjusting the gear ratio limit values and the engine power values in the table.

18. The method of claim 13, wherein adjusting the gear ratio limit further comprises adjusting the gear ratio limit continuously.

19. The method of claim 13, wherein adjusting the gear ratio limit further comprises adjusting the gear ratio limit based on a driving history.

20. The method of claim 13, further comprising dynamically calculating the sensor value threshold.