Homogeneous charge compression ignition engine and air intake and exhaust system thereof

Abstract

An EGR passage partially refluxes exhaust gas to a combustion chamber as an EGR gas. A heat exchanger cools the EGR gas. A heating intake passage branches off from a branching portion formed in a portion of an intake passage on an upstream side of a downstream end of the EGR passage, and its downstream end communicates with a portion of the EGR passage on an upstream side of the heat exchanger. A switch valve adjusts respective amounts of intake air passing through the intake passage and through the heating intake passage. When an EGR valve is closed, an ECU switches the switch valve such that the intake air passes through one of the intake passage and the heating intake passage; when the EGR valve is open, the ECU switches the switch valve such that the intake air passes solely through the intake passage.

1 . A homogeneous charge compression ignition engine, comprising:
 a combustion chamber;   an intake passage serving as a passage for intake air to the combustion chamber;   an exhaust passage serving as a passage for exhaust gas from the combustion chamber;   an EGR passage, communicating with the exhaust passage and the intake passage, for refluxing a part of the exhaust gas from the combustion chamber to the combustion chamber as an EGR gas;   a heat exchanger, provided at some midpoint in the EGR passage, for cooling the EGR gas;   an EGR valve, provided at some midpoint in the EGR passage, for adjusting an opening and closing of the EGR passage;   a heating intake passage which branches off from a branching portion formed in a portion of the intake passage on an upstream side of a downstream end of the EGR passage and whose downstream end communicates with a portion of the EGR passage on an upstream side of the heat exchanger;   a switch valve for adjusting respective amounts of intake air passing through the portion of the intake passage on a downstream side of the branching portion and through the heating intake passage; and   a control means
 which, when the EGR valve is closed, switches the switch valve such that, on the downstream side of the branching portion, the intake air flowing into the combustion chamber passes through at least one of the intake passage and the heating intake passage, and 
 which, when the EGR valve is open, switches the switch valve such that, on the downstream side of the branching portion, the intake air flowing into the combustion chamber passes solely through the intake passage. 
   
     
     
         2 . A homogeneous charge compression ignition engine according to  claim 1 , wherein, in the EGR passage, the EGR valve is provided on the upstream side of the downstream end of the heating intake passage. 
     
     
         3 . A homogeneous charge compression ignition engine according to  claim 1 , wherein the switch valve is provided at the branching portion. 
     
     
         4 . A homogeneous charge compression ignition engine according to  claim 1 , wherein the switch valve and the EGR valve are provided at a communication portion between the heating intake passage and the EGR passage. 
     
     
         5 . A homogeneous charge compression ignition engine according to  claim 1 , wherein the heat exchanger is one through which circulation coolant of an engine passes. 
     
     
         6 . An air intake and exhaust system for use in a homogeneous charge compression ignition engine having a combustion chamber and an exhaust passage serving as a passage for exhaust gas from the combustion chamber, the air intake and exhaust system comprising:
 an intake passage leading to the combustion chamber;   an EGR passage, communicating with the exhaust passage and the intake passage, for refluxing the exhaust gas from the combustion chamber to the combustion chamber as an EGR gas;   a heat exchanger, provided at some midpoint in the EGR passage, for cooling the EGR gas;   an EGR valve, provided at some midpoint in the EGR passage, for opening and closing the EGR passage;   a heating intake passage which branches off from a branching portion formed in a portion of the intake passage on an upstream side of a downstream end of the EGR passage and whose downstream end communicates with a portion of the EGR passage on an upstream side of the heat exchanger;   a switch valve for adjusting respective amounts of intake air passing through the intake passage and through the heating intake passage on a downstream side of the branching portion; and   a control means
 which, when the EGR valve is closed, switches the switch valve such that, on the downstream side of the branching portion, the intake air flowing into the combustion chamber passes through at least one of the intake passage and the heating intake passage, and 
 which, when the EGR valve is open, switches the switch valve such that, on the downstream side of the branching portion, the intake air flowing into the combustion chamber passes solely through the intake passage.