SHIFT TO DIRECT DRIVE DURING COAST CONDITIONS

• US 20100248896A1
• Filed: 03/27/2009
• Published: 09/30/2010
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Dreier, Loren Christopher
• Granted Patent: US 8,343,010 B2
• Time in Patent Office: Days
• US Class Current: 477/118
• CPC Class Codes: F16H 2059/186 Coasting
• CPC Class Codes: F16H 2061/0015 Transmission control for optimising fuel consumptions
• 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

A method and system for automated manual transmission shift methodologies for coasting conditions are disclosed. A coast condition is detected in a vehicle having a transmission that couples prime mover power from a transmission input to a transmission output at a plurality of different gear ratios. A target gear ratio is selected based on the power loss attributes associated with each gear ratio. Each gear ratio is associated with a power loss attribute indicative of a power loss between the transmission input and transmission output when prime mover power is coupled from the transmission input to the transmission output using that gear ratio. The transmission is shifted from a current gear ratio to the target gear ratio if the target and current gear ratios differ. By selecting the target gear ratio, vehicle fuel efficiency is improved, while keeping the vehicle under constant prime mover braking or continuous prime mover control.

Claims

1. A method of changing gear ratios of a transmission in a vehicle, the method comprising:

detecting a coast condition in a vehicle having a transmission operative to couple prime mover power from a transmission input to a transmission output at a plurality of different gear ratios, wherein each gear ratio is associated with a power loss attribute indicative of a power loss between the transmission input and transmission output when the prime mover power is coupled from the transmission input to the transmission output using the associated gear ratio;

selecting a target gear ratio based on the power loss attributes associated with each gear ratio; and

shifting from a current gear ratio to the target gear ratio if the target gear ratio is not the same as the current gear ratio.

2. The method of claim 1, wherein detecting a coast condition comprises detecting a predetermined position of a vehicle brake pedal.

3. The method of claim 1, wherein detecting a coast condition comprises detecting a predetermined position of a vehicle throttle pedal.

4. The method of claim 1, wherein detecting a coast condition comprises detecting a predetermined setting of a power metering device of a prime mover of the vehicle.

5. The method of claim 1, wherein detecting a coast condition comprises detecting a predetermined grade of a road surface the vehicle is travelling on.

6. The method of claim 1, wherein each gear ratio is further associated with a torque multiplier attribute indicative of an effectiveness of the associated gear ratio for prime mover braking, wherein selecting a target gear ratio based on the power loss attributes associated with each gear ratio comprises selecting a target gear ratio based on the power loss attribute and the torque multiplier attribute associated with each gear ratio.

7. A method of changing gear ratios of a transmission in a vehicle, the method comprising:

detecting a coast condition in a vehicle having a transmission operative to couple prime mover power from a transmission input to a transmission output at a plurality of gear ratios, wherein each gear ratio is associated with a power loss attribute indicative of a power loss between the transmission input and transmission output when the prime mover power is coupled from the transmission input to the transmission output using the associated gear ratio, and wherein each gear ratio is associated with a torque multiplier attribute indicative of an effectiveness of the associated gear ratio for prime mover braking;

selecting a target gear ratio based on the power loss attribute and the torque multiplier attribute associated with each gear ratio; and

shifting from a current gear ratio to the target gear ratio if the target gear ratio is not the same as the current gear ratio.

8. The method of claim 7, wherein detecting a coast condition comprises detecting a predetermined position of a vehicle brake pedal.

9. The method of claim 7, wherein detecting a coast condition comprises detecting a predetermined position of a vehicle throttle pedal.

10. The method of claim 7, wherein detecting a coast condition comprises detecting a predetermined setting of a power metering device of a prime mover of the vehicle.

11. The method of claim 7, wherein detecting a coast condition comprises detecting a predetermined grade of a road surface the vehicle is travelling on.

12. A vehicle, comprising:

a prime mover;

a transmission operative to couple prime mover power from a transmission input to a transmission output at a plurality of different gear ratios, wherein each gear ratio is associated with a power loss attribute indicative of a power loss between the transmission input and transmission output when the prime mover power is coupled from the transmission input to the transmission output using the associated gear ratio;

a sensor, operative to receive a signal indicative of a coasting condition of the vehicle; and

a controller, in communication with the sensor and the transmission, operative to;

shift to a current gear ratio of the transmission;

detect a coasting condition;

select a target gear ratio based the power loss attribute associated with each gear ratio; and

shift from the current gear ratio to the target gear ratio if the target gear ratio is not the same as the current gear ratio.

13. The vehicle of claim 12, wherein detecting a coast condition comprises detecting a predetermined position of a vehicle brake pedal.

14. The vehicle of claim 12, wherein detecting a coast condition comprises detecting a predetermined position of a vehicle throttle pedal.

15. The vehicle of claim 12, wherein detecting a coast condition comprises detecting a predetermined setting of a power metering device of a prime mover of the vehicle.

16. The vehicle of claim 12, wherein detecting a coast condition comprises detecting a predetermined grade of a road surface the vehicle is travelling on.

17. The vehicle of claim 12, wherein each gear ratio is further associated with a torque multiplier attribute indicative of an effectiveness of the associated gear ratio for prime mover braking, wherein selecting a target gear ratio based on the power loss attributes associated with each gear ratio comprises selecting a target gear ratio based on the power loss attribute and the torque multiplier attribute associated with each gear ratio.