Intake control apparatus for an engine and method

Abstract

An engine intake control apparatus for an engine that comprises at least one combustion chamber operatively connected to an intake port and an intake valve associated with each intake port, wherein the intake valve is adapted to open and close the intake port is disclosed herein. The intake control apparatus comprises a variable valve operating mechanism and a controller. The variable valve operating mechanism is configured and arranged to selectively change a valve closing timing and a valve lift amount of the intake valve. The controller is configured and arranged to control the variable valve operating mechanism when the engine is in a low load condition. The valve closing timing is determined such that an actual compression ratio of the engine is reduced relative to the actual compression ratio when the engine is operating in a high load condition. The valve lift amount is smaller when the engine is in the low load condition relative to the valve lift amount when the engine is in the high load condition. A method for controller an engine is also disclosed.

1. An engine intake control apparatus for an engine that comprises at least one combustion chamber operatively connected to an intake port and an intake valve associated with each intake port, wherein the intake valve is adapted to open and close the intake port, the intake control apparatus comprising:
 a variable valve operating mechanism configured and arranged to selectively change a valve closing timing and a valve lift amount of the intake valve; and 
 a controller configured and arranged to control the variable valve operating mechanism when the engine is in a low load condition, wherein, the controller using the variable valve operating mechanism to set the valve closing timing is determinedof the intake valve such that an actual compression ratio of the engine is reduced relative to the actual compression ratio when the engine is operating in a high load condition upon detecting that the engine is in a low load condition and that a temperature of a combustion chamber wall is less than or equal to a predetermined value, and 
 whereinthe controller using the variable valve operating mechanism to set the valve lift amount isof the intake valve to be smaller when the engine is in the low load condition relative to the valve lift amount of the intake valve set by the controller when the engine is in the high load condition upon detecting that the engine is in the low load condition and that the temperature of the combustion chamber wall is less than or equal to the predetermined value. 
 
     
     
       2. The intake control apparatus as described in  claim 1 , wherein
 at least a portion of the wall surfaces of the combustion chamber wall is made of a heat insulating material. 
 
     
     
       3. The engine intake control apparatus as described in  claim 2 , wherein
 the heat insulating material is a ceramic material. 
 
     
     
       4. The engine intake control apparatus as described in  claim 2 , wherein
 the heat insulating material is coated on a cylinder liner of the engine. 
 
     
     
       5. The engine intake control apparatus as described in  claim 1 , wherein
 a cylinder wall that forms part of the combustion chamber wall has a first liner part positioned next to a piston at a top dead center side with the first liner part having a lower thermal conductivity than a portion of the cylinder wall second liner part positioned next to the piston at a bottom dead center side. 
 
     
     
       6. The engine intake control apparatus as described in  claim 5 , wherein
 a top dead center side of the cylinder wallthe first liner part is constructed of a first material, and the bottom dead center side of the cylinder wallsecond liner part is constructed of a second material, and 
 wherein the first material is a heat insulating material and the second material is a conductive material. 
 
     
     
       7. The engine intake control apparatus as described in  claim 5 , wherein
 athe first cylinder liner forms the top dead center side of the cylinder wall and part is constructed of the a first material and a the second cylinder liner forms the bottom dead center side of the cylinder wall and part is constructed of the a second material that is different from the first material. 
 
     
     
       8. The engine intake control apparatus as described in  claim 1 , wherein
 the controller reduces the valve lift amount of the intake valves is reduced sufficiently to letthereby letting an intake air flow into the combustion chamber along the wall surfaces of the combustion chamber wall when the engine is in the low load condition. 
 
     
     
       9. The engine intake control apparatus as described in  claim 1 , wherein
 the controller sets the valve closing of the intake valves is set to occur prior to the bottom dead center of an intake stroke when the engine is operating in the low load condition, thereby reducing the actual compression ratio. 
 
     
     
       10. The engine intake control apparatus as described in  claim 1 , wherein
 the variable valve operating mechanism comprises a variable lift mechanism that selectively varies the valve lift amount of the intake valves, and a variable valve closing timing mechanism that selectively varies the valve closing timing of the intake valves. 
 
     
     
       11. The engine intake control apparatus as described in  claim 1 , wherein
 when the engine is in a the low load condition, the valve lift amount of the intake valve is increased by the controller when a the temperature of a the combustion chamber wall exceeds a the predetermined temperature as compared to when the temperature of the combustion chamber wall is lower than the predetermined temperature. 
 
     
     
       12. The engine intake control apparatus as described in  claim 1 , wherein
 when the engine is in the high load condition, the controller actuates the variable valve operating mechanism to increase the valve lift amount of the intake valves so as to alleviate intake air flow from flowing along the wall surfaces of the combustion chamber wall. 
 
     
     
       13. A method for controlling an engine that comprises at least one combustion chamber that is operatively connected to an intake port through an intake valve that selectively and variably opens and closes the intake port, the method comprising:
 detecting an engine operational condition to determine whether the engine is in a low load condition; and 
 actuating an intake valve with a valve closing timing and a valve lift amount when the engine is in the low load condition; 
 whereinsetting the valve closing timing is determined such thatof the intake valve to reduce an actual compression ratio of the engine is reduced relative to the actual compression ratio of the engine with when the engine is in a high load condition upon detecting that the engine is in the low load condition and that a temperature of a combustion chamber wall is less than or equal to a predetermined temperature; and 
 whereinsetting the valve lift amount isof the intake valve to be smaller when the engine is in a low load condition relative to the valve lift amount of the intake valve when the engine is in the high load condition upon detecting that the engine is in the low load condition and that the temperature of the combustion chamber wall is less than or equal to the predetermined temperature. 
 
     
     
       14. The method for controlling the engine as described in  claim 13 , wherein
 when a the temperature of a the combustion chamber wall exceeds a the predetermined temperature, the valve lift amount is increased relative to the valve lift amount when the temperature of the combustion chamber wall is lower than the predetermined temperature. 
 
     
     
       15. An intake control apparatus for an engine that comprises at least one combustion chamber operatively connected to an intake port and an intake valve associated with each intake port, wherein the intake valve is adapted to open and close the intake port, the intake control apparatus comprising:
 variable valve operating means for selectively changing a valve closing timing and a valve lift amount of the intake valve; and 
 control means for controlling the variable valve operating means when the engine is in a low load condition, wherein
 to set the valve closing timing is determinedof the intake valve such that an actual compression ratio of the engine is reduced relative to the actual compression ratio when the engine is operating in a high load condition upon detecting that the engine is in a low load condition and that a temperature of a combustion chamber wall is less than or equal to a predetermined value, and 
 whereinto set the valve lift amount isof the intake valve to be smaller when the engine is in a low load condition relative to the valve lift amount of the intake valve set by the control means when the engine is in the high load condition upon detecting that the engine is in the low load condition and that the temperature of the combustion chamber wall is less than or equal to the predetermined value.