Method of controlling transmission in neutral

Patent metadata

Field	Value
Publication number	US-11041534-B2
Application number	US-201916525138-A
Country	US
Kind code	B2
Filing date	Jul 29, 2019
Priority date	Jul 30, 2018
Publication date	Jun 22, 2021
Grant date	Jun 22, 2021

Abstract

Ideally, when a transmission is in Neutral, no torque should be exerted on the vehicle wheels by the powertrain. However, even with all clutches in a gearbox disengaged, some torque may be transmitted from a turbine shaft to the transmission output due to clutch drag and transmission component inertia. To avoid transmitting torque, a subset of clutches may be engaged to produce an input tie-up state, this holding the turbine shaft against rotation while permitting rotation of the output element.

First claim

What is claimed is:

1. A transmission comprising:
a fluid coupling having an impeller and a turbine;
a gearbox including a plurality of clutches and an output element, the gearbox being configured to establish various speed ratios between the turbine and the output, wherein one of the clutches is a one-way clutch; and
a controller programmed to, responsive to (i) selection of a Neutral mode and (ii) a transmission fluid temperature being less than a threshold, engage a subset of the plurality of the clutches to hold the turbine stationary while permitting rotation of the output element, wherein the subset includes the one-way clutch.

2. The transmission of claim 1 , wherein the controller is programmed to transition from a Drive or Reverse mode to the Neutral mode by releasing a first clutch of the plurality of clutches and engaging a second clutch of the plurality of clutches.

3. The transmission of claim 1 , wherein the one-way clutch is a selectable one-way clutch having a passive state in which the selectable one-way clutch is permitted to overrun having an active state in which the selectable one-way clutch is locked.

4. A transmission comprising:
a fluid coupling having an impeller and a turbine;
a gearbox including a plurality of clutches and an output element, the gearbox being configured to establish various speed ratios between the turbine and the output element, wherein one of the clutches of the gearbox is a selectable one-way clutch having a passive state in which the selectable one-way clutch is permitted to overrun in a first direction and lock in a second direction and having an active state in which the selectable one-way clutch is locked in both the first and second directions; and
a controller programmed to, responsive to selection of a Neutral mode, engage a subset of the plurality of the clutches to hold the turbine stationary while permitting rotation of the output element, wherein the selectable one-way clutch is included in the subset.

5. The transmission of claim 4 , wherein the fluid coupling further includes a stator.

6. The transmission of claim 4 , wherein the controller is programmed to transition from a Drive or Reverse mode to the Neutral mode by releasing a first clutch of the plurality of clutches and engaging a second clutch of the plurality of clutches.

7. The transmission of claim 4 , wherein at least one of the clutches of the subset is a two-way clutch.

8. The transmission of claim 4 , wherein one of the clutches of the subset is a brake.

9. The transmission of claim 4 , wherein the engagement of the subset of clutches to hold the turbine stationary is performed further responsive to a transmission fluid temperature being less than a threshold.

10. A transmission comprising:
a fluid coupling having an impeller and a turbine;
a housing;
a gearbox disposed in the housing and including:
a turbine shaft connected to the turbine,
an output element,
a selectable one-way clutch having a passive state in which the selectable one-way clutch is permitted to overrun in a first direction and lock in a second direction and having an active state in which the selectable one-way clutch is locked in both the first and second directions, and
a plurality of two-way clutches; and
a controller programmed to:
in response to the transmission being switched from a Drive mode to a Neutral mode and the selectable one-way clutch slipping below a threshold speed, command the selectable one-way clutch to the active state, command engagement of a first of the two-way clutches, and command disengagement of a remainder of the two-way clutches so the output element is permitted to rotate and the turbine shaft is rotationally locked to the housing, and
in response to the transmission being switched from the Drive mode to the Neutral mode and the selectable one-way clutch slipping above the threshold speed, command engagement of a second and a third of the two-way clutches and command disengagement of a remainder of the two-way clutches.

11. The transmission of claim 10 , wherein the controller is further programmed to, in response to the transmission being in the Neutral mode, the second and third two-way clutches being engaged, and the selectable one-way clutch slipping below the threshold speed, (i) command the selectable one-way clutch to the active state, (ii) disengage the second and third two-way clutches once the one-way clutch is in the active state, and (iii) engage the first two-way clutch once the second and third two-way clutches are disengaged.

12. The transmission of claim 10 , wherein the second two-way clutch is a brake.

13. The transmission of claim 12 , wherein the second two-way clutch circumscribes the third two-way clutch.

14. The transmission of claim 10 , wherein the controller is further programmed to, in response to the transmission being switched from a reverse mode to the neutral mode, command disengagement of the second of the two-way clutches and command engagement of the first of the two-way clutches.

15. The transmission of claim 14 , wherein the first of the two-way clutches is engaged subsequent to the disengagement of the second of the two-way clutches.

16. The transmission of claim 10 , wherein the controller is further programmed to, in response to the transmission being switched from a Park mode to the Neutral mode, command engagement of at least one of the two-way clutches such that the transmission is in a full tied-up condition, command the selectable one-way clutch to the active state, command engagement of the first of the two-way clutches, command release of a parking pawl, and command disengagement of the at least one of the two-way clutches.

17. The transmission of claim 10 , wherein the threshold speed is less than 20 revolutions per minute.

18. The transmission of claim 10 , wherein the selectable one-way clutch is a brake when in the active state.

Assignees

• Ford Global Tech Llc

Inventors

• Cicala Stephen Michael
• Diakiw Markian Oleh
• Sullivan Conor Edward
• Li Dongdong Dee
• Fedullo Timothy
• Riedle Bradley Dean
• Gittins Scott Joseph
• Wincek Peter

Classifications

• F16H63/3458

  with electric actuating means, e.g. shift by wire · CPC title

• F16H2061/0481

  during range shift from drive (D) or reverse (R) to neutral (N) · CPC title

• F16H2200/2082

  one freewheel mechanisms · CPC title

• F16H63/3425

  characterised by pawls or wheels · CPC title

• F16H2059/467

  of torque converter · CPC title