Hybrid vehicle and downshifting strategy in a hybrid vehicle

Patent metadata

Field	Value
Publication number	US-9758149-B2
Application number	US-201514603749-A
Country	US
Kind code	B2
Filing date	Jan 23, 2015
Priority date	Jan 23, 2015
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A vehicle includes an engine, an electric machine, an engine disconnect clutch, and a transmission input configured to transmit power from the engine and electric machine to a transmission. The vehicle also includes a controller program to close the disconnect clutch and start the engine before downshifting in response to an anticipated transmission downshift in which a predicted speed of the transmission input after the downshift will be outside a predetermined speed range or a torque capacity of the electric machine will be less than a predicted required torque after the downshift.

First claim

What is claimed is:

1. A method of downshifting a transmission in a hybrid vehicle comprising:
in response to an anticipated downshift in which a predicted impeller speed of a torque converter, which is an input to the transmission, will be outside a predetermined speed range after the downshift, closing a disconnect clutch configured to selectively couple an engine and electric machine, starting the engine, and downshifting the transmission after starting the engine.

2. The method of claim 1 , wherein the predicted impeller speed is based on a predicted vehicle speed after the downshift.

3. The method of claim 2 , wherein the predicted vehicle speed is based on a current vehicle speed and a driver demand to alter the current vehicle speed.

4. The method of claim 1 , wherein the predicted impeller speed is also based on an expected slip across a bypass clutch of the torque converter after the downshift.

5. A method of downshifting a transmission in a hybrid vehicle comprising:
in response to an anticipated downshift in which a torque capacity of an electric machine will be less than a predicted demanded impeller torque of a torque converter after the downshift, closing a disconnect clutch configured to selectively couple an engine and the electric machine, starting the engine, and downshifting the transmission after starting the engine.

6. The method of claim 5 , wherein the predicted demanded impeller torque is based on a desired output torque of the transmission after the downshift.

7. The method of claim 6 , wherein the desired output torque of the transmission is based on a currently desired output torque of the transmission and a driver demand to alter the desired output torque of the transmission.

8. The method of claim 5 , wherein the predicted demanded impeller torque is based on a demanded torque of an input to the transmission after the downshift.

9. The method of claim 8 , wherein the demanded torque of the input is based on a current demanded torque of the input and a driver demand to alter the current demanded torque of the input.

10. The method of claim 5 , wherein the predicted demanded impeller torque is also based on an expected slip across a bypass clutch of the torque converter after the downshift.

11. A vehicle comprising:
an engine;
an electric machine;
a disconnect clutch configured to selectively couple the engine and electric machine;
a torque converter configured to transmit power from the engine and electric machine to a transmission; and
a controller programmed to, in response to an anticipated transmission downshift in which a predicted impeller speed of the torque converter after the downshift will be outside a predetermined speed range or a torque capacity of the electric machine will be less than a predicted demanded impeller torque of the torque converter after the downshift, close the disconnect clutch and start the engine before downshifting.

12. The vehicle of claim 11 , wherein the predicted impeller speed is also based on an expected slip across a bypass clutch of the torque converter after the downshift.

13. The vehicle of claim 11 , wherein the predicted impeller speed of the torque converter is based on a current vehicle speed and a driver demand to alter the current vehicle speed.

14. The vehicle of claim 11 , wherein the predicted demanded impeller torque of the torque converter is based on a currently desired output torque of the transmission and a driver demand to alter the desired output torque of the transmission.

Assignees

• Ford Global Tech Llc

Inventors

• Doering Jeffrey Allen
• Wang Xiaoyong
• Nedorezov Felix
• Zhang Chen
• Mccullough Todd
• Johri Rajit

Classifications

• B60W2710/1005

  Transmission ratio engaged · CPC title

• B60W10/06

  including control of combustion engines · CPC title

• B60W2540/10

  Accelerator pedal position · CPC title

• B60K6/547

  the transmission being a stepped gearing · CPC title

• B60W2510/025

  Slip change rate · CPC title