Methods and systems for boost control

Patent metadata

Field	Value
Publication number	US-9309836-B2
Application number	US-201313965901-A
Country	US
Kind code	B2
Filing date	Aug 13, 2013
Priority date	Aug 13, 2013
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Methods and systems are provided for varying a proportion of compressed air recirculated to a compressor inlet from a location downstream of the compressor and upstream of a charge air cooler and a location downstream of the charge air cooler. A temperature-controlled compressor recirculation flow is used to reduce condensation from EGR being ingested into the compressor. The temperature-controlled compressor recirculation flow is also used to address compressor surge.

First claim

The invention claimed is:

1. A method of controlling a boosted engine, comprising:
determining, via an electronic control unit, engine operating conditions; and
adjusting, via at least one valve, a relative amount of compressed air recirculated to a compressor inlet from a first passage downstream of a compressor and downstream of an intercooler, and from a second passage downstream of the compressor and upstream of the intercooler based on an estimated compressor inlet temperature and an EGR amount received via an EGR passage merging with the first and second passages;
wherein the EGR amount includes exhaust residuals recirculated from downstream of an exhaust turbine to the compressor inlet via the EGR passage, the EGR passage merging with the first and second passages at a junction of the first and the second passage, upstream of the compressor inlet.

2. The method of claim 1 ,
wherein the adjusting includes adjusting the relative amount of the compressed air recirculated to the compressor inlet to maintain the compressor inlet temperature above a threshold temperature, and
wherein the compressed air recirculated to the compressor inlet from the first passage includes cooled compressed air cooled upon passing through the intercooler, and
wherein the compressed air recirculated to the compressor inlet from the second passage includes warm compressed air not cooled upon passing through the intercooler.

3. The method of claim 2 , wherein the threshold temperature is based on ambient conditions including ambient temperature and ambient humidity.

4. The method of claim 3 , wherein the threshold temperature is increased as the ambient humidity increases, and wherein the threshold temperature is decreased as the ambient temperature increases.

5. The method of claim 4 , wherein the threshold temperature is further based on the EGR amount, the threshold temperature increased as a water content in the EGR amount increases, the threshold temperature decreased as the ambient temperature increases or the amount of the EGR delivered via an EGR valve in the EGR passage decreases.

6. The method of claim 5 , wherein the adjusting includes, increasing the relative amount of compressed air recirculated along the second passage while correspondingly decreasing the relative amount of compressed air recirculated along the first passage as the compressor inlet temperature falls below the threshold temperature.

7. The method of claim 6 , wherein the EGR amount is in a low pressure EGR passage including the exhaust residuals recirculated from downstream of the exhaust turbine to upstream of the compressor.

8. The method of claim 7 , wherein the adjusting, via the at least one valve, based on the EGR amount includes increasing the relative amount of compressed air recirculated along the second passage while decreasing the relative amount of compressed air recirculated along the first passage as the water content in the EGR amount increases.

9. The method of claim 8 , wherein decreasing the relative amount of compressed air recirculated along the first passage includes decreasing an opening of a first valve in the first passage, and wherein increasing the relative amount of compressed air recirculated along the second passage includes increasing an opening of a second valve in the second passage.

10. The method of claim 7 , wherein the adjusting, via the at least one valve, based on the EGR amount includes decreasing the relative amount of compressed air recirculated along the second passage while increasing the relative amount of compressed air recirculated along the first passage as one or more of an EGR temperature increases and the EGR amount decreases.

11. The method of claim 1 , wherein adjusting the relative amount via the at least one valve includes adjusting an opening of a proportioning valve coupled at a junction of the first and second passages, upstream of the compressor inlet.

12. A method of controlling a turbocharged engine, comprising:
determining, via an electronic control unit, engine operating conditions;
adjusting, via at least one valve, a proportion of compressor recirculation flow received at a compressor inlet from a first location downstream of an intercooler and a second location upstream of the intercooler; and
mixing the compressor recirculation flow with an EGR flow, received at the compressor inlet from downstream of an exhaust turbine via an EGR passage, upstream of the compressor inlet before delivering the mixture to the compressor inlet.

13. The method of claim 12 ,
wherein the compressor recirculation flow from the second location is at a higher temperature than the compressor recirculation flow from the first location, and
wherein the adjusting, via the at least one valve, the proportion of compressor recirculation flow, based on the engine operating conditions includes adjusting based on a temperature difference between the compressor recirculation flow from the first location and the second location.

14. The method of claim 13 , wherein the adjusting is further based on each of a compressor inlet temperature, an EGR temperature, an EGR amount, an EGR humidity, an ambient humidity, and an intake air temperature.

15. The method of claim 14 , wherein the adjusting includes adjusting the proportion of compressor flow from the first location relative to the second location to raise the compressor inlet temperature above a threshold temperature, the threshold temperature based on each of the EGR humidity, the ambient humidity, and the intake air temperature, the threshold temperature raised as the EGR humidity or the ambient humidity increases or as the intake air temperature or ambient pressure decreases.

16. The method of claim 14 , wherein the adjusting includes:
increasing, via the at least one valve, the proportion of recirculation flow from the second location while correspondingly decreasing the proportion of recirculation flow from the first location as the compressor inlet temperature or the EGR temperature decreases; and
increasing, via the at least one valve, the proportion of recirculation flow from the second location while decreasing the proportion of recirculation flow from the first location as the EGR humidity or the ambient humidity increases, as the EGR amount increases, and/or as the intake air temperature decreases.

17. An engine system, comprising:
an engine including an intake and an exhaust;
a compressor for compressing intake air, the compressor driven by an exhaust turbine;
an intercooler located downstream of the compressor for cooling the compressed intake air;
a first passage for recirculating compressed intake air from downstream of the intercooler to a compressor inlet;
a second passage for recirculating compressed intake air from upstream of the intercooler to the compressor inlet;
one or more valves coupled to the first and second passages;
an EGR passage for recirculating exhaust gas flow from downstream of the turbine to upstream of the compressor; and
a controller with computer readable instructions stored in a non-transitory medium for:
during a first condition, adjusting the one or more valves coupled to the first and second passages to decrease a ratio of compressed air recirculated along the first passage relative to the second passage in a first direction responsive to EGR condensation; and
during a second condition, adjusting the one or more valves coupled to the first and second passages to increase the ratio of compressed air recirculated along the first passage relative to the second passage in a second,

Assignees

• Ford Global Tech Llc

Inventors

• Ulrey Joseph Norman
• Buckland Julia Helen
• Mcconville Gregory Patrick

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02M26/00 Primary

  Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems · CPC title

• F02B29/0493

  Controlling the air charge temperature · CPC title

• F02B29/04 Primary

  Cooling of air intake supply · CPC title

• F02M25/0709

  Mechanical Engineering · mapped topic