Method and system for exhaust air injection

Patent metadata

Field	Value
Publication number	US-11073059-B2
Application number	US-201916548707-A
Country	US
Kind code	B2
Filing date	Aug 22, 2019
Priority date	Aug 22, 2019
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

Methods and systems are provided for improving catalyst temperature control while reducing oxygen saturation. Secondary air is injected at a location downstream of the catalyst during selected conditions. A mixing valve position is coordinated with the air injection to improve local turbulence and thereby enhance air and fuel mixing in the exhaust passage, in at least one arrangement.

First claim

The invention claimed is:

1. A method for operating an engine system including a controller, comprising:
injecting air downstream of a catalyst without injecting air upstream of the catalyst in an exhaust passage by operating a secondary air injection system of the engine system via the controller responsive to an exhaust temperature upstream of the catalyst being greater than a first threshold and an exhaust temperature downstream of the catalyst being greater than a second threshold, the exhaust temperature upstream of the catalyst detected via a first temperature sensor and the exhaust temperature downstream of the catalyst detected via a second temperature sensor.

2. The method of claim 1 , further comprising adjusting a position of a flow mixing valve towards a closed position via the controller when injecting air upstream of the catalyst.

3. The method of claim 2 , wherein the flow mixing valve is positioned upstream of the catalyst.

4. The method of claim 1 , further comprising injecting air both upstream and downstream of the catalyst in response to the exhaust temperature upstream of the catalyst detected via the first temperature sensor decreasing below the first threshold and the exhaust temperature downstream of the catalyst being detected via the second temperature sensor greater than the second threshold.

5. The method of claim 4 , further comprising adjusting a flow mixing valve positioned downstream of the catalyst towards a closed position via the controller when injecting air downstream of the catalyst.

6. The method of claim 1 , wherein the secondary air injection system provides port electric thermactor air (PETA).

7. A method for operating an engine system including a controller, comprising:
detecting an exhaust temperature upstream of a catalyst that is less than a first threshold via a first temperature sensor;
detecting an exhaust temperature downstream of the catalyst that is less than a second threshold via a second temperature sensor;
opening a first flow valve positioned upstream of the catalyst via the controller to introduce port electric thermactor air (PETA) into a passage upstream of the catalyst; and
holding a second flow valve positioned downstream of the catalyst in a closed position via the controller to prevent introduction of PETA air into a passage downstream of the catalyst.

8. The method of claim 7 , wherein the first threshold and the second threshold are different threshold temperatures stored in the controller.

9. The method of claim 7 , further comprising adjusting an upstream mixing valve towards a closed position via the controller, wherein the upstream mixing valve is positioned immediately upstream of the catalyst.

10. The method of claim 9 , wherein the upstream mixing valve is a throttle valve.

11. The method of claim 7 , wherein an air-fuel ratio downstream of the second flow valve is unmetered.

12. A method for operating an engine system including a controller, comprising:
during a first condition,
detecting an upstream exhaust temperature that is less than a first threshold via a first temperature sensor, the upstream exhaust temperature being a temperature upstream of a catalyst;
detecting a downstream exhaust temperature that is greater than a second threshold via a second temperature sensor, the downstream exhaust temperature being a temperature downstream of the catalyst;
injecting port electric thermactor air (PETA) both upstream and downstream of the catalyst by operating a secondary air injection system of the engine system via the controller; and
adjusting a position of an upstream mixing valve towards a closed position via the controller, the upstream mixing valve positioned immediately upstream of the catalyst.

13. The method of claim 12 , wherein the FETA injection is downstream of the catalyst and further downstream of all exhaust oxygen sensors.

14. The method of claim 12 , further comprising,
during a second condition,
detecting that the upstream exhaust temperature is greater than the first threshold via the first temperature sensor;
detecting that the downstream exhaust temperature is greater than the second threshold via the second temperature sensor;
injecting PETA downstream of the catalyst without PETA injection upstream of the catalyst by operating the secondary air injection system of the engine system via the controller;
adjusting the upstream mixing valve to a fully open position via the controller; and
adjusting a position of a downstream mixing valve towards a closed position via the controller, wherein the downstream mixing valve is positioned downstream of the catalyst.

15. The method of claim 14 , wherein the first condition is an engine cold start condition, and wherein the second condition is an engine hot start condition.

16. The method of claim 12 , wherein the first threshold and the second threshold are different threshold temperatures.

Assignees

• Ford Global Tech Llc

Inventors

• Williams Jason
• Roth John M

Classifications

• F01N2560/06

  the means being a temperature sensor · CPC title

• F01N3/30 Primary

  Arrangements for supply of additional air (control, e.g. using by-passes or variable air pump drives, F01N3/22) · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02D41/1446

  the characteristics being exhaust temperatures · CPC title

• F01N2900/1404

  Exhaust gas temperature · CPC title