Vehicle control during tip-in

Patent metadata

Field	Value
Publication number	US-10131357-B2
Application number	US-201715430940-A
Country	US
Kind code	B2
Filing date	Feb 13, 2017
Priority date	Feb 13, 2017
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

A vehicle powertrain includes an engine and a transmission, each controlled by controllers that communicate with one another. When the vehicle is coasting in certain gears, a one-way clutch over-runs. When the driver depresses the accelerator pedal (tips in), the transmission controller adjusts a transmission torque demand limit which is communicated to the engine controller. In response, the engine controller adjusts the engine torque, resulting in a smooth re-engagement of the one-way clutch.

First claim

What is claimed is:

1. A vehicle powertrain comprising:
an engine;
an engine controller programmed to command the engine to produce a torque equal to the lesser of a driver demand torque based on a pedal position and a transmission torque limit;
a transmission gearbox having a one-way clutch with a slip speed; and
a transmission controller in communication with the engine controller and programmed to
respond to the slip speed decreasing to less than a first threshold by reducing the transmission torque limit to less than the driver demand torque; and
respond to the slip speed further decreasing to less than a second threshold by gradually increasing the transmission torque limit to the driver demand torque.

2. The vehicle powertrain of claim 1 further comprising a torque converter having an impeller fixed to a crankshaft of the engine and a turbine fixed to an input of the gearbox.

3. The vehicle of claim 2 wherein the first threshold is a function of a turbine acceleration rate.

4. The vehicle powertrain of claim 3 wherein the second threshold is a function of the turbine acceleration rate.

5. The vehicle powertrain of claim 1 wherein the transmission controller is further programmed to increase the transmission torque limit to a level substantially higher than the driver demand torque after the slip decreases to zero.

6. A method of controlling a transmission comprising:
operating the transmission in a coasting gear state in which a one-way clutch overruns with a slip speed;
in response to the slip speed decreasing to less than a first threshold, requesting an engine torque reduction; and
in response to the slip speed further decreasing to less than a second threshold, increasing the requested engine torque gradually back to a driver demand level based on a pedal position.

7. The method of claim 6 wherein the first threshold is a function of a turbine acceleration rate.

8. The method of claim 7 wherein the second threshold is a function of the turbine acceleration rate.

9. A method of controlling a powertrain comprising:
while a one-way clutch is overrunning with a slip speed, increasing an engine torque in response to depression of a pedal;
in response to the slip speed subsequently decreasing to less than a first threshold, reducing the engine torque; and
in response to the slip speed further decreasing to less than a second threshold, ramping the engine torque to a level based on a position of the pedal.

10. The method of claim 9 wherein the first threshold is a function of a turbine acceleration rate.

11. The method of claim 10 wherein the second threshold is a function of the turbine acceleration rate.

Assignees

• Ford Global Tech Llc

Inventors

• Nickerson Kurt Howard
• Riedle Bradley Dean
• Morrison Kendrick
• Zhang Jianping
• Laroche Cory Benson

Classifications

• B60W2710/105

  Output torque · CPC title

• B60W2540/10

  Accelerator pedal position · CPC title

• B60W2510/0241

  Clutch slip, i.e. difference between input and output speeds · CPC title

• B60W10/06 Primary

  including control of combustion engines · CPC title

• B60W2710/0666

  Engine torque · CPC title