Method for crankcase ventilation in a boosted engine

Patent metadata

Field	Value
Publication number	US-2017009679-A1
Application number	US-201514792124-A
Country	US
Kind code	A1
Filing date	Jul 6, 2015
Priority date	Jul 6, 2015
Publication date	Jan 12, 2017
Grant date	—

Abstract

Methods and systems are provided for enhancing crankcase ventilation in a boosted engine. During boosted conditions, a crankcase may be ventilated via vacuum generated at an aspirator coupled in a compressor bypass passage. However, when the aspirator is plugged, pressure in the crankcase may be relieved by flowing crankcase gases through an aspirator bypass passage.

First claim

1 . A method for a boosted engine, comprising:
during a first condition,
generating vacuum at an aspirator positioned in a compressor bypass passage;
using the vacuum to draw gases from a crankcase; and
reducing a pressure in the crankcase; and
during a second condition,
reducing the pressure in the crankcase via a bypass passage coupled to an intake passage and the crankcase.

2 . The method of claim 1 , wherein the first condition includes boosted conditions wherein compressed air from downstream of a compressor flows through the aspirator in the compressor bypass passage to generate vacuum at the aspirator, and wherein the second condition includes boosted conditions wherein the aspirator is plugged and compressed air from downstream of the compressor does not flow through the aspirator.

3 . The method of claim 2 , wherein the bypass passage fluidically couples the crankcase to an engine intake passage upstream of the compressor.

4 . The method of claim 3 , wherein the bypass passage bypasses the aspirator coupled in the compressor bypass passage, and wherein pressure in the crankcase is reduced by flowing gases from the crankcase through the bypass passage.

5 . The method of claim 4 , wherein the bypass passage includes a check valve positioned to allow flow of gases from the crankcase towards the intake passage and block fluid flow from the engine intake passage to the crankcase.

6 . The method of claim 4 , wherein the bypass passage includes an electronically controlled valve, and wherein the electronically controlled valve is opened during the second condition.

7 . A method for a boosted engine, comprising:
during a first condition,
generating vacuum at an aspirator positioned in a compressor bypass passage;
drawing vapors from a crankcase using the vacuum generated at the aspirator; and
during a second condition,
adjusting an opening of an air induction system (AIS) throttle to generate AIS vacuum; and
drawing vapors from the crankcase with the AIS vacuum through an aspirator bypass passage.

8 . The method of claim 7 , wherein the first condition includes boosted conditions wherein compressed air from downstream of a compressor flows through the aspirator in the compressor bypass passage to generate vacuum at the aspirator, and wherein the second condition includes boosted conditions wherein the aspirator is plugged and compressed air from downstream of the compressor does not flow through the aspirator.

9 . The method of claim 8 , wherein adjusting the opening of the AIS throttle includes reducing the opening of the AIS throttle, and wherein the AIS throttle is positioned in an intake passage upstream of the compressor.

10 . The method of claim 9 , wherein the aspirator bypass passage fluidically couples the crankcase to the intake passage downstream of the AIS throttle and upstream of the compressor.

11 . The method of claim 8 , wherein the aspirator is determined to be plugged based on an output of a crankcase pressure sensor.

12 . The method of claim 7 , further comprising relieving a positive pressure in the crankcase during each of the first condition and the second condition.

13 . The method of claim 7 , further comprising, during non-boosted conditions when a pressure in an intake manifold of the boosted engine is lower than atmospheric pressure, flowing vapors from the crankcase directly to the intake manifold via a crankcase ventilation valve.

14 . A system, comprising:
an engine; a compressor coupled in an intake passage; a compressor bypass passage coupled across the compressor for flowing compressed air from downstream of the compressor to an inlet of the compressor; an ejector positioned within the compressor bypass passage, the ejector having a suction port; a crankcase; a crankcase pressure sensor coupled to the crankcase; a suction path fluidically coupling the crankcase to the suction port of the ejector; an ejector bypass passage fluidically coupling the crankcase to the inlet of the compressor, the ejector bypass passage bypassing the ejector; an electronically controlled valve positioned in the ejector bypass passage; an exhaust turbine coupled in an exhaust passage; a bypass conduit around the exhaust turbine; a wastegate coupled in the bypass conduit; and a controller with computer readable instructions stored in non-transitory memory for: during boosted conditions,
applying vacuum generated by the ejector to the crankcase;
drawing crankcase gases into the ejector; and
relieving pressure in the crankcase; and
in response to detecting plugging of the ejector,
opening the electronically controlled valve arranged in the ejector bypass passage to relieve pressure in the crankcase; and
adjusting the wastegate to reduce boost in the engine.

15 . The system of claim 14 , wherein plugging of the ejector is detected based on an output of the crankcase pressure sensor.

16 . The system of claim 14 , wherein vacuum is generated by the ejector during boosted conditions due to motive flow through the ejector and the compressor bypass passage, and wherein drawing crankcase gases into the ejector includes drawing crankcase gases through the suction path into the suction port of the ejector.

17 . The system of claim 14 , wherein adjusting the wastegate to reduce boost in the engine further includes increasing an opening of the wastegate to increase flow of exhaust gases through the bypass conduit around the exhaust turbine to reduce boost.

18 . The system of claim 17 , wherein the controller includes further instructions for increasing the opening of the wastegate in response to compressor surge.

19 . The system of claim 14 , further comprising an air induction system (AIS) throttle positioned in the intake passage upstream of the compressor.

20 . The system of claim 19 , wherein the controller includes further instructions for adjusting the AIS throttle towards a more closed position in response to detecting plugging of the ejector during boosted conditions.

Assignees

• Ford Global Tech Llc

Inventors

• Pursifull Ross Dykstra
• Steadman Mark
• Brewer Katherine Jane

Classifications

• F01M13/04

  having means for purifying air before leaving crankcase, e.g. removing oil · CPC title

• F01M2013/0044

  with one or more valves · CPC title

• F02B37/164

  the bypassed air being used in an auxiliary apparatus, e.g. in an air turbine · CPC title

• F02D41/0025 Primary

  Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures · CPC title

• F01M13/023

  Control valves in suction conduit · CPC title