Hybrid electric vehicle and method of control

Patent metadata

Field	Value
Publication number	US-9440643-B1
Application number	US-201514665540-A
Country	US
Kind code	B1
Filing date	Mar 23, 2015
Priority date	Mar 23, 2015
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

A vehicle and a method of controlling a vehicle are provided. The vehicle may include a controller programmed to, in response to a change from a first to a second powertrain operating mode, operate an engine and electric machine to increase a state of charge target of a traction battery to increase propulsion torque available from the electric machine. The controller may be further programmed to, in response to a decrease in accelerator pedal position and a vehicle speed being less than a threshold speed while operating the powertrain in the second powertrain operating mode and the engine and electric machine are coupled via a friction element, decrease a pressure of the friction element to a first target pressure to decouple the engine from the electric machine.

First claim

What is claimed is:

1. A vehicle comprising:
a powertrain including a battery, an engine, and an electric machine selectively coupled to the engine; and
a controller programmed to, in response to a request to transition powertrain operation from a first mode to a second mode, increase a battery state of charge target based on an electric propulsion torque availability and an expected engine torque lag to increase the electric propulsion torque availability as compared to the first mode.

2. The vehicle of claim 1 wherein increasing the battery state of charge target includes increasing a lower limit associated with the battery state of charge target.

3. The vehicle of claim 1 wherein the controller is further programmed to output for display an indicator indicative of an increased battery state of charge target.

4. The vehicle of claim 1 further comprising a friction element configured to selectively couple the engine and electric machine, wherein the controller is further programmed to, in response to an accelerator pedal position falling below a threshold while the powertrain is operating in the second mode and the engine is operating and coupled to the electric machine, decrease a pressure associated with the friction element to decouple the engine from the electric machine and continue operating the engine.

5. The vehicle of claim 4 wherein the friction element includes first and second components spaced apart from one another and configured to synchronously rotate while the engine is operating and decoupled from the electric machine.

6. The vehicle of claim 5 wherein the controller is further programmed to decrease the pressure such that the first and second components are held near a touch point while the engine is operating and decoupled from the electric machine.

7. The vehicle of claim 4 wherein the controller is further programmed to, in response to the accelerator pedal position exceeding the threshold, increase the pressure to couple the engine to the electric machine.

8. The vehicle of claim 7 wherein the controller is further programmed to, in response to coupling the engine to the electric machine, operate the electric machine to provide a propulsion torque based on a state of charge of the battery and the accelerator pedal position.

9. A vehicle comprising:
a controller programmed to,
in response to a transition from a first powertrain operating mode to a second powertrain operating mode, operate an engine and electric machine to increase a state of charge target of a traction battery to increase propulsion torque available from the electric machine, wherein the state of charge target of the traction battery is based on an electric propulsion torque availability and an expected engine torque lag; and
in response to a decrease in accelerator pedal position and a vehicle speed being less than a threshold speed while a powertrain of the vehicle is operating in the second powertrain operating mode and the engine and electric machine are coupled via a friction element, decrease a pressure of the friction element to a first target pressure to decouple the engine from the electric machine.

10. The vehicle of claim 9 wherein the controller is further programmed to, in response to the vehicle speed being less than the threshold speed and a state of charge being greater than the state of charge target, decrease the pressure to a second target pressure less than the first target pressure, and shut down the engine.

11. The vehicle of claim 9 wherein the controller is further programmed to, in response to a decrease in the accelerator pedal position and the vehicle speed being greater than a threshold speed while the powertrain is operating in the second powertrain operating mode, maintain the pressure.

12. The vehicle of claim 9 wherein the friction element includes a first component spaced apart from a second component and the controller is further programmed to, in response to a decrease in the accelerator pedal position and the vehicle speed being less than a threshold speed while the powertrain is operating in the second powertrain operating mode, decrease the pressure such that the first component and second component are released proximate a touch point.

13. The vehicle of claim 12 wherein the engine is operated to rotate the first component and the electric machine is operated to rotate the second component such that the first and second components are synchronously rotated while the engine is decoupled from the electric machine.

14. The vehicle of claim 12 wherein the controller is further programmed to, in response to the accelerator pedal position exceeding a threshold, increase the pressure and operate the engine and the electric machine to satisfy a demand for torque from the powertrain associated with the accelerator pedal position.

15. A method of controlling a vehicle comprising:
in response to a transition from a first powertrain operating mode to a second powertrain operating mode, increasing a traction battery state of charge target, wherein the traction battery state of charge target is based on an electric propulsion torque availability and an expected engine torque lag;
operating a powertrain to achieve the traction battery state of charge target; and
in response to a decrease in accelerator pedal position and a vehicle speed being less than a threshold, decreasing a pressure of a friction element configured to selectively couple an engine and transmission of the powertrain such that no torque is transmitted to the transmission by the engine while the engine continues operating.

16. The method of claim 15 wherein the pressure is decreased such that a first and second component of the friction element are held proximate a touch point while the engine is operating and decoupled from the transmission.

17. The method of claim 15 wherein increasing the traction battery state of charge target includes maintaining a traction battery state of charge upper limit and increasing a traction battery state of charge lower limit.

18. The method of claim 15 further comprising
in response to the accelerator pedal position exceeding a threshold, increasing the pressure to couple the engine to the transmission, and
operating the powertrain to satisfy a demand associated with the accelerator pedal position.

Assignees

• Ford Global Tech Llc

Inventors

• Yamazaki Mark Steven
• Wang Xiaoyong
• Johri Rajit
• Liang Wei
• Kuang Ming Lang
• Doering Jeffrey Allen

Classifications

• B60W2710/083

  Torque · CPC title

• B60K6/442

  Series-parallel switching type · CPC title

• B60W2710/06

  Combustion engines, Gas turbines · CPC title

• B60W20/20 Primary

  Control strategies involving selection of hybrid configuration, e.g. selection between series or parallel configuration · CPC title

• B60W10/26

  for electrical energy, e.g. batteries or capacitors · CPC title