Method and control for operating a transmission in neutral

Patent metadata

Field	Value
Publication number	US-2018118214-A1
Application number	US-201615337540-A
Country	US
Kind code	A1
Filing date	Oct 28, 2016
Priority date	Oct 28, 2016
Publication date	May 3, 2018
Grant date	—

Abstract

A vehicle powertrain includes an engine and a transmission coupled to the engine. The transmission has a first neutral state in which a first combination of clutches are engaged and a second neutral state in which a second combination of clutches are engaged. A vehicle controller is programmed to, in response to the transmission being in the first neutral state and an engine-torque request exceeding a threshold value, shift the transmission to the second neutral state.

First claim

What is claimed is:

1 . A vehicle powertrain comprising:
an engine; a transmission coupled to the engine and including a first neutral state in which a first combination of clutches are engaged and a second neutral state in which a second combination of clutches are engaged; and a controller programmed to, in response to the transmission being in the first neutral state and an engine-torque request exceeding a threshold value, shift the transmission to the second neutral state.

2 . The vehicle powertrain of claim 1 , wherein the controller is further programmed to shift the transmission back to the first neutral state in response to the engine-torque request being below a threshold value.

3 . The vehicle powertrain of claim 2 , wherein the transmission is shifted back to the first neutral state after the engine-torque request is below the threshold value for a threshold amount of time.

4 . The vehicle powertrain of claim 1 , wherein the controller is further programmed to:
limit engine torque to a magnitude less than the engine-torque request in response to the transmission being in the first neutral state and the engine-torque request exceeding the threshold value; and increasing engine torque to a magnitude substantially equal to the engine-torque request in response to the transmission being in the second neutral state.

5 . The vehicle powertrain of claim 1 , wherein the first neutral state has a first number of clutches engaged, and the second neutral state has a second number of clutches engaged that is less than the first number.

6 . The vehicle powertrain of claim 1 , wherein the second neutral state has a smaller inertia-coupling value than the first neutral state.

7 . A vehicle powertrain comprising:
an engine; a transmission coupled to the engine and including planetary gear sets and shift actuators engageable with one or more components of the planetary gear sets; and a controller programmed to, in response to the transmission being in a first neutral state and an engine-torque request exceeding a threshold valve, disengaging at least one of the shift actuators to place the transmission in a second neutral state.

8 . The vehicle powertrain of claim 7 , wherein the controller is further programmed to re-engage at least one of the shift actuators to shift the transmission back into the first neutral state in response to the engine-torque request being below a second threshold value.

9 . The vehicle powertrain of claim 7 , wherein the controller is further programmed to limit engine torque to a magnitude less than the engine-torque request in response to the transmission being in the first neutral state and the engine-torque request exceeding the threshold value.

10 . The vehicle powertrain of claim 9 , wherein the controller further programmed to limit engine torque to a magnitude less than the engine-torque request for a predefined time.

11 . The vehicle powertrain of claim 9 , wherein the controller is further programmed to increase engine torque to a magnitude substantially equal to the engine-torque request in response to the transmission being in the second neutral state.

12 . The vehicle powertrain of claim 7 , wherein the first neutral state has a larger inertia-coupling value than the second neutral state.

13 . The vehicle powertrain of claim 7 , wherein the engine-torque request is based on a pedal position of an accelerator pedal.

14 . A method of controlling clutches of a transmission, the method comprising:
engaging a first combination of the clutches to generate a first neutral state in response to the transmission being in PARK or NEUTRAL; and disengaging one of the clutches of the first combination of clutches to generate a second neutral state in response to an engine-torque request exceeding a threshold value while the transmission is in the first neutral state.

15 . The method of claim 14 further comprising limiting engine torque to a magnitude less than the engine-torque request in response to the transmission being in the first neutral state and the engine-torque request exceeding the threshold value.

16 . The method of claim 15 further comprising increasing engine torque to a magnitude substantially equal to the engine-torque request in response to the transmission being in the second neutral state.

17 . The method of claim 14 further comprising re-engaging the one of the clutches to shift the transmission back into the first neutral state in response to the engine-torque request being below a threshold value.

18 . The method of claim 14 further comprising shifting the transmission to the first neutral state in response to a gear selector being actuated by a driver.

Assignees

• Ford Global Tech Llc

Inventors

• Mcdonnell Alexander Phillip
• Cicala Stephen Michael
• Suter Charles William
• Riedle Bradley Dean
• Kiliaris Leonidas
• Diakiw Markian Oleh
• Nickerson Kurt Howard

Classifications

• F16H2059/6823

  Sensing neutral state of the transmission · CPC title

• F16H2200/0069

  the gear ratios comprising ten forward speeds · CPC title

• F16H61/0202

  the signals being electric · CPC title

• F16H2059/147

  Transmission input torque, e.g. measured or estimated engine torque · CPC title

• B60W2540/16

  Ratio selector position · CPC title