Variable valve timing system for an internal combustion engine

Abstract

An engine with a valve actuator to extend duration of a valve event and method of controlling an engine with such an actuator are disclosed. The actuator may include an actuator cylinder with an actuator piston. The actuator contains an electrorheological fluid. A magnetic flux may be applied the electrorheological fluid to prevent or slow movement of the actuator piston and change valve movement with respect to its regular, cyclical operation provide for with a cam. A biasing means is connected with the actuator piston to allow positioning of the valve actuator in an existing engine design.

What is claimed is:  
     
         1 . An engine valve actuator, comprising: 
 an actuator cylinder;    a electromagnetic coil connected with at least a portion of said actuator cylinder;    an actuator piston reciprocatingly disposed in said actuator cylinder, said actuator piston having an actuating surface and a control surface opposite said actuating surface;    a biasing means being operatively connected with said control surface; and    an electrorheological fluid disposed in at least a portion of said actuator cylinder.    
     
     
         2 . The engine valve actuator of  claim 1  including a flow control device fluidly connecting said actuating surface with said control surface.  
     
     
         3 . The engine valve actuator of  claim 2  wherein said control device is an orifice in said actuator piston.  
     
     
         4 . The engine valve actuator of  claim 1  wherein said biasing means is a spring connected between said control surface and said actuator cylinder.  
     
     
         5 . The engine valve actuator of  claim 1  wherein said electromagnetic coil is integral with said actuator cylinder.  
     
     
         6 . The engine valve actuator of  claim 1  wherein said biasing means includes: 
 a control piston reciprocatingly positioned in said actuating cylinder, said control piston having a second biasing means, said control piston being adapted to reduce a control volume in said actuating cylinder; and  
 a flow control device fluidly connecting said control piston with said control surface.  
 
     
     
         7 . The engine valve actuator of  claim 6  wherein said second biasing means is a spring connecting between said control piston and said actuating cylinder.  
     
     
         8 . The engine valve actuator of  claim 6  wherein said control device is an orifice.  
     
     
         9 . An engine valve actuator, comprising: 
 an actuator cylinder;    an actuator piston reciprocatingly disposed in said actuator cylinder;    an electromagnetic coil connecting with at least a portion of said actuator cylinder;    an electrorheological fluid disposed in at least a portion of said actuator cylinder;    a control cylinder fluidly connecting with said actuator cylinder through a flow control device;    a control piston reciprocatingly disposed in said control cylinder; and    a biasing means being operatively connected with said control piston, said biasing means being adapted expel said electrorheological fluid from said control cylinder.    
     
     
         10 . The engine valve actuator of  claim 9  wherein said biasing means is a spring.  
     
     
         11 . The engine valve actuator of  claim 9  wherein said actuator cylinder and said control cylinder are formed by a single cylinder divided by a partition.  
     
     
         12 . The engine valve actuator of  claim 11  wherein said control device is an orifice in said partition.  
     
     
         13 . An internal combustion engine having valves with variable timing, said engine comprising: 
 an engine block defining an engine cylinder;    a piston reciprocatingly positioned in said engine cylinder;    a cylinder head being connected with said engine block, said head defining an inlet port and an exhaust port;    an intake valve positioned in said inlet port, said valve being adapted to restrict flow through said intake port to said cylinder;    an exhaust valve positioned in said exhaust port, said valve being adapted to restrict flow through said exhaust port to said cylinder;    a cam being connected with said intake valve and said exhaust valve to cyclically move said intake valve and said exhaust valve; and    an engine valve actuator connected with said intake valve, said valve actuator including: an actuator cylinder having an actuator piston reciprocatingly positioned in said actuator cylinder, an electrorheological fluid being contained in said actuator cylinder, an electromagnetic coil being proximate said electrorheological fluid, and a biasing means being connected with a control surface of said actuator piston.    
     
     
         14 . The engine of  claim 13  wherein said biasing means is a spring.  
     
     
         15 . The engine of  claim 13  wherein said biasing means includes: 
 a control cylinder;  
 a control piston reciprocatingly positioned in said control cylinder; and  
 a second biasing means being connected with said control piston, said biasing means being adapted to reduce a control volume in fluid communication with said control surface.  
 
     
     
         16 . The engine of  claim 15  including a flow control device between said control volume and said control surface.  
     
     
         17 . The engine of  claim 13  including a controller being connected with said engine valve actuator.