Method and system for a boosted engine

Patent metadata

Field	Value
Publication number	US-10731577-B2
Application number	US-201715847332-A
Country	US
Kind code	B2
Filing date	Dec 19, 2017
Priority date	Dec 19, 2017
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

Methods and systems are provided for improving transient performance in a boosted engine having staged air compression systems. An electric supercharger compressor is staged downstream of a turbocharger compressor in a bypass, airflow diverted from a main intake passage to the bypass via closure of a bypass valve. During selected conditions when the supercharger compressor is not being spun, the bypass valve may be closed to direct air to the engine after flowing through the supercharger in a stand-by mode, thereby enabling a transient increase in torque demand to be rapidly met.

First claim

The invention claimed is:

1. A method for a boosted engine, comprising:
during selected low load conditions when an electrically-driven compressor coupled to a turbine-driven compressor is not activated, commanding a bypass valve closed to direct intake air to an engine via the deactivated electrically-driven compressor, wherein the electrically-driven compressor being deactivated includes no electrical power being provided to an electric motor coupled to the electrically-driven compressor, and no electrical power being generated by the electric motor; and
adjusting a counter electromotive force applied by an alternator coupled to the electric motor to enable freewheeling of the electrically-driven compressor.

2. The method of claim 1 , wherein the closing is in anticipation of a tip-in from the selected low load conditions to an engine operating condition where boost assistance from the electrically-driven compressor is required.

3. The method of claim 1 , wherein the selected low load conditions include low load conditions where engine fuel economy with the bypass valve closed and the electrically-driven compressor deactivated is higher than engine fuel economy with the bypass valve open and the electrically-driven compressor deactivated.

4. The method of claim 1 , wherein the selected low load conditions include engine speed increasing from rest to a first threshold speed and decreasing from the first threshold speed to a second threshold speed, and, concurrently, engine load increasing from a first load to a first threshold load, and then decreasing from the first threshold load to a second load, the second load lower than the first load.

5. The method of claim 4 , wherein a rate of the increasing engine speed from rest to the first threshold speed is higher than a rate of decreasing engine speed from the first threshold speed to the second threshold speed, and wherein a rate of the increasing engine load from the first load to the first threshold load is higher than a rate of the decreasing engine load from the first threshold load to the second load.

6. The method of claim 1 , wherein the turbine-driven compressor is coupled in an intake passage, and wherein the electrically-driven compressor is coupled in a bypass passage, the bypass passage coupled to the intake passage upstream of the bypass valve.

7. The method of claim 6 , wherein directing intake air to the engine via the deactivated electrically-driven compressor includes diverting all the intake air from the intake passage into the bypass passage, and flowing all the intake air from the bypass passage to the engine upon passage through the deactivated electrically-driven compressor.

8. The method of claim 1 , wherein the turbine-driven compressor is staged upstream of the electrically-driven compressor, and wherein the selected low load conditions include the electrically-driven compressor not being choke limited.

9. A method for a boosted engine, comprising:
during selected low load conditions when an electrically-driven compressor coupled to a turbine-driven compressor is not activated, commanding a bypass valve closed to direct intake air to an engine via the deactivated electrically-driven compressor, and further comprising:
monitoring a speed of the electrically-driven compressor during the directing of intake air to the engine via the deactivated electrically-driven compressor; and
indicating that the bypass valve is stuck at least partially open responsive to the monitored speed being lower than a threshold speed after commanding the bypass valve closed.

10. A method for a boosted engine, comprising:
prior to an anticipated increase in torque demand, selectively raising a pressure ratio across an electric supercharger by diverting intake air through a deactivated compressor of the electric supercharger from downstream of a deactivated turbocharger compressor.

11. The method of claim 10 , wherein the diverting includes closing a bypass valve coupled in an intake passage downstream of the turbocharger compressor to divert all of the intake air to engine cylinders via a bypass housing the electric supercharger.

12. The method of claim 11 , wherein the selectively raising includes closing the bypass valve in an engine speed-load region where fuel economy with the bypass valve closed is higher than a threshold, the engine speed-load region mapped by overlaying an engine brake specific fuel consumption map with the bypass valve closed onto a corresponding map with the bypass valve open.

13. The method of claim 11 , further comprising, responsive to an actual increase in torque demand, while maintaining the bypass valve closed, activating the supercharger compressor to further raise the pressure ratio based on the increased torque demand.

14. The method of claim 11 , further comprising indicating that the bypass valve is stuck open responsive to supercharger compressor speed being lower than a threshold during the diverting of the intake air.

15. The method of claim 10 , wherein the diverting of the intake air through the deactivated compressor includes freewheeling the deactivated compressor of the electric supercharger without providing electrical power from an electric motor to the deactivated compressor, and without generating electrical power at the electric motor from the deactivated compressor.

16. A vehicle system, comprising:
an engine;
a branched intake passage system including a common upstream intake passage branching into first and second parallel branches, and rejoining into a common downstream intake passage;
a twin turbocharger including a first intake compressor in the first branch, driven by a first exhaust turbine, and a second intake compressor in the second branch, driven by a second exhaust turbine;
a twin supercharger including a third intake compressor driven by a first electric motor, the third intake compressor housed in a first bypass passage bypassing the common downstream intake passage, and a fourth intake compressor driven by a second electric motor, the fourth intake compressor housed in a second bypass passage bypassing the common downstream intake passage, the first bypass passage and the second bypass passage parallel to each other and to the common downstream passage;
a bypass valve coupled in the common downstream passage, downstream of an inlet of each of the first and second bypass passages; and
a controller with computer readable instructions stored on non-transitory memory for:
while operating the engine with each of the first, second, third, and fourth intake compressors deactivated, selectively closing the bypass valve to direct all intake air to the engine via a combination of the first and second branches, and then via a combination of the first and second bypass passages, while bypassing the common downstream passage, the selectively closing based on engine fuel economy with the bypass valve closed relative to bypass valve open; and
responsive to an increase in torque demand, maintaining the bypass valve closed while activating the third and fourth intake compressors.

17. The system of claim 16 , wherein the selectively closing is further based on a choke limit of each of the third and fourth intake compressors.

18. The system of claim 16 , further comprising a sensor for estimating a rotation speed of at least one of the third and fourth compressors, wherein the controller includes further instructions for indicating degradation of the bypass valve responsive to a lower than threshold change in rotation speed of the at least one of the third an

Assignees

• Ford Global Tech Llc

Inventors

• Kelly Tyler
• Mariucci Vincent

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02B37/013 Primary

  with exhaust-driven pumps arranged in series · CPC title

• F02B37/162

  by bypassing, e.g. partially, intake air from pump inlet to pump outlet · CPC title

• F02B33/40 Primary

  of non-positive-displacement type · CPC title

• F02D41/0007 Primary

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title