Power-off downshift engagement dampening

• US 8,308,609 B2
• Filed: 06/14/2010
• Issued: 11/13/2012
• Est. Priority Date: 06/14/2010
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Holland, Shawn A., Walker, Ralph S., Herr, George, Tumavitch, Jeffrey J., Riedle, Bradley D., Meisner, Steven C., Jiang, Hong, Shelton, Matthew J.
• Primary Examiner(s): YOUNG, EDWIN
• Application Number:
  US12/814,550
• Publication Number:
  US 20110306464A1
• Time in Patent Office: 883 Days
• Field of Search: 477/77
• US Class Current: 477/77
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/113 with two input flow paths, e.g. double clutch transmission selection of one of the torque flow paths by the corresponding input clutch
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2061/0496 for low engine torque, e.g. during coasting, sailing or engine braking
• CPC Class Codes: F16H 2306/54 Synchronizing engine speed to transmission input speed
• CPC Class Codes: F16H 2342/044 Torque transmitting capability
• CPC Class Codes: F16H 61/0403 Synchronisation before shifting
• CPC Class Codes: F16H 63/46 Signals to a clutch outside the gearbox

Abstract

A method for controlling a power-off downshift in a powershift transmission includes disengaging the current gear, synchronizing engine speed and a speed of the target gear layshaft by increasing a torque capacity of the target gear clutch, disengaging the clutch, engaging the target gear, and reengaging the clutch.

Claims

1. A method for controlling a power-off downshift in a powershift transmission, comprising:

(a) disengaging a current gear;

(b) using a torque capacity of a target gear clutch to synchronize engine speed and a speed of a target gear layshaft;

(c) disengaging said clutch;

(d) engaging the target gear;

(e) reengaging said clutch.

2. The method of claim 1, wherein step (a) further comprises:

disengaging a coupler that connects one of a plurality of gears that produces the current gear from a layshaft on which said gear is supported.

3. The method of claim 1, wherein step (a) further comprises:

disengaging a coupler that connects one of a plurality of gears that produces the current gear from a layshaft on which said gear is supported; and

maintaining said coupler in a neutral position.

4. The method of claim 1, wherein step (b) further comprises increasing engine speed to a speed greater than a current speed of the target gear layshaft before synchronizing engine speed and a speed of the target gear layshaft.

5. The method of claim 1, wherein step (b) further comprises increasing a torque capacity of the target gear clutch.

6. The method of claim 1, wherein step (c) further comprises producing a stepwise reduction in torque capacity of the target gear clutch.

7. The method of claim 1, wherein step (d) further comprises:

using a coupler to produce a drive connection between one of a plurality of gears that produces the target gear and a layshaft on which said gear is supported.

8. A method for controlling a power-off downshift in a powershift transmission, comprising:

(a) disengaging a current gear from driven vehicle wheels;

(b) increasing engine speed to a speed greater than a current speed of a target gear layshaft;

(c) using a torque capacity of a target gear clutch to synchronize engine speed and a speed of a target gear layshaft;

(d) disengaging said clutch;

(e) engaging the target gear;

(f) reengaging said clutch.

9. The method of claim 8, wherein step (a) further comprises:

moving to a neutral position a sleeve of a coupler that connects one of a plurality of gears that produces the current gear.

10. The method of claim 8, wherein step (a) further comprises:

moving to a neutral position a sleeve of a coupler that connects one of a plurality of gears that produces the current gear; and

maintaining said coupler sleeve in the neutral position.

11. The method of claim 8, wherein step (c) further comprises increasing a torque capacity of the target gear clutch.

12. The method of claim 8, wherein step (d) further comprises producing a stepwise reduction in torque capacity of the target gear clutch.

13. The method of claim 8, wherein step (e) further comprises:

using a coupler to produce a drive connection between one of a plurality of gears that produces the target gear and a layshaft on which said one of a plurality of gears is supported.