METHOD OF TRANSITIONING AMONG SHIFT SCHEDULES

• US 20160059845A1
• Filed: 08/26/2014
• Published: 03/03/2016
• Est. Priority Date: 08/26/2014
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: NEFCY, BERNARD D., COLVIN, DANIEL SCOTT, SHELTON, MATTHEW JOHN, YAMAZAKI, MARK STEVEN
• Granted Patent: US 9,533,677 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 20/14 in conjunction with braking regeneration
• 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 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 30/18127 Regenerative braking
• CPC Class Codes: B60W 30/182 Selecting between different operative modes, e.g. comfort and performance modes
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements

Abstract

A hybrid electric vehicle having a discrete ratio transmission shifts according to distinct shift schedules in various operating modes. For example, different shift schedules may be used for operating with the engine off, operating with the engine running, and regenerative braking. When the vehicle transitions from one mode to another, the new shift schedule may schedule a shift that the driver would not expect. To avoid annoying the driver, a control strategy inhibits the shift until either the old strategy would also schedule a shift or a customer event occurs.

Claims

1. A method of operating a hybrid vehicle having a discrete ratio transmission comprising:

operating the vehicle in a first engine state by shifting the transmission according to a first shift schedule;

operating the vehicle in a second engine state by shifting the transmission according to a second shift schedule;

while in a first transmission ratio as selected by the first shift schedule, transitioning from the first engine state to the second engine state at a first vehicle speed and first pedal position at which the second shift schedule would select a second transmission ratio different than the first transmission ratio; and

immediately following the transition from the first engine state to the second engine state, maintaining the transmission in the first transmission ratio.

2. The method of claim 1, further comprising:

in response to a change, while maintaining the first transmission ratio, to a second vehicle speed and second pedal position at which the first shift schedule would select the second transmission ratio, shifting the transmission from the first transmission ratio to the second transmission ratio.

3. The method of claim 1, further comprising:

in response to a customer event, while maintaining the first transmission ratio, shifting the transmission from the first transmission ratio to the second transmission ratio.

4. The method of claim 3 wherein the customer event comprises a change in pedal position exceeding a threshold magnitude and occurring within less than a threshold time interval.

5. The method of claim 1 wherein the first engine state is an engine off state and the second engine state is an engine running state.

6. The method of claim 1 wherein the first engine state is an engine running state and the second engine state is an engine off state.

7. A hybrid vehicle comprising:

an engine;

a discrete ratio transmission selectively coupled to the engine by a disconnect clutch; and

a controller programmed to

while the engine is running and an accelerator pedal is held at a pedal position, upshift from a first transmission ratio to a second transmission ratio in response to the vehicle accelerating through a first vehicle speed,

while the engine is not running and the accelerator pedal is held at the pedal position, upshift from the first transmission ratio to the second transmission ratio in response to the vehicle accelerating through a second vehicle speed greater than the first speed, and

while the engine is not running, the vehicle is moving at a third vehicle speed between the first and second vehicle speeds, and the accelerator pedal is held at the pedal position, start the engine and maintain the transmission in the first transmission ratio.

8. The hybrid vehicle of claim 7 wherein the controller is further programmed to:

after starting the engine and maintaining the transmission in the first transmission ratio, upshift to the second transmission ratio in response to the vehicle accelerating through the second vehicle speed.

9. The hybrid vehicle of claim 7 wherein the controller is further programmed to:

after starting the engine and maintaining the transmission in the first transmission ratio, upshift to the second transmission ratio in response to a customer event.

10. A method of operating a hybrid vehicle comprising:

operating the vehicle in a first mode by shifting a transmission according to a first shift schedule;

operating the vehicle in a second mode by shifting the transmission according to a second shift schedule; and

upon transitioning from the first mode to the second mode, delaying a next shift triggered by the second shift schedule.

11. The method of claim 10 further comprising, completing the next shift triggered by the second shift schedule in response to a change in a vehicle speed and a pedal position such that the first shift schedule would trigger a shift in a same direction.

12. The method of claim 10 further comprising, completing the next shift triggered by the second shift schedule in response to a customer event.

13. The method of claim 10 further comprising, upon transitioning from the first mode to the second mode, starting an engine and engaging a disconnect clutch.

14. The method of claim 13 wherein transitioning from the first mode to the second mode occurs in response to a battery state of charge decreasing below a threshold.

15. The method of claim 10 further comprising, upon transitioning from the first mode to the second mode, releasing a disconnect clutch and stopping an engine.

16. The method of claim 15 wherein transitioning from the first mode to the second mode occurs in response to a battery state of charge increasing above a threshold.

17. The method of claim 16 wherein transitioning from the first mode to the second mode occurs in response to a regenerative braking torque increasing above a threshold.