Crankcase breech detection for boosted engines

Abstract

Methods for indicating whether a crankcase of an engine is breeched are provided. One example method comprises restricting a communication of the crankcase with atmosphere, acting to increase or decrease a crankcase pressure, and indicating whether the crankcase is breeched based on the crankcase pressure. Another example method comprises sensing a crankcase pressure component, and indicating whether the crankcase is breeched based on the crankcase pressure component, the crankcase communicating with atmosphere via a conduit, a restrictedness of the conduit responsive to one or more of a crankcase pressure and a signal from an electronic control unit of the motor vehicle. Still other examples provide more particular methods for indicating whether the crankcase is breeched, and example configurations that enable the various methods.

1 . A method for indicating whether a crankcase of an engine is breeched, the method comprising:
 restricting a communication of the crankcase with atmosphere;   acting to increase or decrease a crankcase pressure; and   indicating whether the crankcase is breeched based on the crankcase pressure.   
   
   
       2 . The method of  claim 1 , further comprising sensing the crankcase pressure via a sensor coupled to the crankcase. 
   
   
       3 . The method of  claim 1 , wherein restricting a communication of the crankcase with atmosphere comprises closing one or more electronically actuable valves. 
   
   
       4 . The method of  claim 1 , wherein acting to increase or decrease a crankcase pressure comprises selectably coupling the crankcase to a source of pressure. 
   
   
       5 . The method of  claim 1 , wherein acting to increase or decrease a crankcase pressure comprises selectably coupling the crankcase to a source of vacuum. 
   
   
       6 . The method of  claim 1 , wherein the engine includes a PCV system, and where acting to increase or decrease a crankcase pressure includes influencing the PCV system to cause a net flow of gas into or out of the crankcase. 
   
   
       7 . The method of  claim 1 , wherein indicating whether the crankcase is breeched based on the crankcase pressure comprises indicating the crankcase breeched if, on acting to increase or decrease a crankcase pressure, the crankcase pressure fails to respond as expected. 
   
   
       8 . The method of  claim 1 , wherein indicating whether the crankcase is breeched based on the crankcase pressure comprises indicating that an oil fill cap or dipstick is unseated. 
   
   
       9 . The method of  claim 1 , wherein indicating whether the crankcase is breeched based on the crankcase pressure comprises indicating that a sealing element fluidically coupled to the crankcase is leaking. 
   
   
       10 . A method for indicating whether a crankcase of an engine is breeched, the engine operatively coupled to an electronic control unit, the method comprising:
 sensing a crankcase pressure component;   indicating whether the crankcase is breeched based on the crankcase pressure component, the crankcase communicating with atmosphere via a conduit, a restrictedness of the conduit responsive to one or more of a crankcase pressure and a signal from the electronic control unit.   
   
   
       11 . The method of  claim 10 , further comprising acting to delay a depletion of lubricant from the crankcase if the crankcase is indicated breeched. 
   
   
       12 . The method of  claim 11 , wherein acting to delay a depletion of lubricant from the crankcase includes one or more of reducing an intake of air into the engine and adding lubricant to the crankcase. 
   
   
       13 . The method of  claim 10 , wherein the crankcase pressure component is derived from the crankcase pressure by low-pass filtering. 
   
   
       14 . The method of  claim 10 , wherein the crankcase pressure component is an alternating component of the crankcase pressure, and the crankcase is indicated breeched if an amplitude of the crankcase pressure component is below a threshold. 
   
   
       15 . The method of  claim 14 , wherein the sensing the crankcase pressure component comprises synchronizing a sampling of the crankcase pressure to an operational state of the engine. 
   
   
       16 . The method of  claim 10 , further comprising restricting a communication of the crankcase with atmosphere. 
   
   
       17 . The method of  claim 16 , further comprising restricting a communication of the crankcase with an intake of the engine. 
   
   
       18 . The method of  claim 16 , further comprising acting to increase the crankcase pressure and indicating the crankcase breeched if the crankcase pressure component stays below a threshold. 
   
   
       19 . The method of  claim 16 , further comprising acting to decrease the crankcase pressure and indicating the crankcase breeched if the crankcase pressure component stays above a threshold. 
   
   
       20 . The method of  claim 10 , further comprising:
 coupling the crankcase to a pressure or vacuum source;   isolating the crankcase from the pressure or vacuum source;   indicating the crankcase breeched based on a rate of approach of the crankcase pressure component to atmospheric pressure.   
   
   
       21 . An engine system having a crankcase and configured to indicate whether the crankcase is breeched, the engine system comprising:
 a sensor having an output responsive to a crankcase pressure;   an electronic control unit configured to sample the output and to indicate whether the crankcase is breeched based on the output, the crankcase communicating with atmosphere via a breather conduit, a restrictedness of the breather conduit responsive to one or more of the crankcase pressure and a signal from the electronic control unit.   
   
   
       22 . The engine system of  claim 21 , further comprising a check valve disposed in the breather conduit, wherein the output includes an alternating output, and the electronic control unit is further configured to indicate the crankcase breeched if the alternating output more closely matches an output expected for a breeched crankcase than an output expected for an unbreeched crankcase. 
   
   
       23 . The engine system of  claim 21 , further comprising an electronically actuable PCV valve operatively coupled to the electronic control unit, wherein the electronic control unit is further configured to open the electronically actuable PCV valve wide at idle and to indicate the crankcase breeched if the output fail to indicate an expected level of vacuum in the crankcase. 
   
   
       24 . The engine system of  claim 21 , further comprising an electronically actuable check valve disposed in the breather conduit, wherein the electronic control unit is further configured to admit a flow of air through the electronically actuable check valve and to indicate the crankcase breeched if the output fail to indicate an expected level of vacuum in the crankcase. 
   
   
       25 . The engine system of  claim 21 , further comprising an electronically actuable check valve disposed in the breather conduit, wherein the electronic control unit is further configured to admit a flow of crankcase head gas through the electronically actuable check valve and to indicate the crankcase breeched if the output fail to indicate an expected level of pressure. 
   
   
       26 . The engine system of  claim 21 , further comprising an electronically actuable normally open valve disposed in the breather conduit and operatively coupled to the electronic control unit, wherein the electronic control unit is further configured to indicate the crankcase breeched if the output fail to indicate one or more of an expected level of pressure during push-over and an expected level of vacuum during clean-air purge. 
   
   
       27 . The engine system of  claim 21 , further comprising a first electronically actuable normally open valve disposed in the breather conduit and a second electronically actuable normally open valve disposed in a PCV inlet conduit of the engine, wherein the electronic control unit is further configured to close the first and second normally open valves and to indicate the crankcase breeched if the output fail to indicate an expected level of pressure when the first and second normally open valves are closed. 
   
   
       28 . The engine system of  claim 21 , further comprising an electronically actuable pressure or vacuum port coupled to the crankcase, wherein the electronic control unit is further configured to actuate the electronically actuable pressure or vacuum port and to indicate the crankcase breeched if the output fail to indicate an expected level of pressure or vacuum when the electronically actuable pressure or vacuum port is actuated. 
   
   
       29 . The engine system of  claim 21 , further comprising an intake throttle and an electronically actuable PCV by-pass valve configured to couple the crankcase to an intake of the engine, wherein the electronic control unit is further configured to open the electronically actuable PCV by-pass valve and to indicate the crankcase breeched if the output fail to indicate an expected level of vacuum in the crankcase while cranking the engine with the electronically actuable PCV by-pass valve open and the intake throttle closed.