Variable valve timing mechanism

Abstract

Embodiments of the disclosure provide variable valve timing (VVT) mechanisms. A VVT mechanism according to the disclosure can include: a lever having a first end, a second end, and a fulcrum positioned therebetween; a length-adjustable push rod coupled to the first end of the lever and including an actuator therein; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and an engine control unit (ECU) operatively connected to the actuator of the length-adjustable push rod, wherein the ECU adjusts a length of the length-adjustable push rod based on an operating condition of the engine system. In addition or alternatively, the ECU can control an amount of cushioning fluid for the valves to affect the rate at which the intake valve opens or closes.

What is claimed is: 
     
         1 . A variable valve timing (VVT) mechanism comprising:
 a lever having a first end, a second end, and a fulcrum positioned therebetween;   a length-adjustable push rod coupled to the first end of the lever and including an actuator therein;   a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and   an engine control unit (ECU) operatively connected to the actuator of the length-adjustable push rod, wherein the ECU adjusts a length of the length-adjustable push rod based on an operating condition of the engine system.   
     
     
         2 . The VVT mechanism of  claim 1 , wherein the length-adjustable push rod further includes a first member and a second member each coupled to an opposing end of the actuator, and wherein one of the first member and the second member further includes a sleeve for receiving the actuator therein. 
     
     
         3 . The VVT mechanism of  claim 1 , further comprising:
 a spring positioned circumferentially about the rod valve, and interposed between the second end of the lever and the intake valve of the engine system; and   a position sensor operatively connected to the ECU, wherein the ECU further adjusts the length-adjustable push rod in response to detecting a compression of the spring.   
     
     
         4 . The VVT mechanism of  claim 3 , further comprising a cam lobe coupled to the length-adjustable push rod, wherein the position sensor measures a position of the cam lobe to detect the compression of the spring. 
     
     
         5 . The VVT mechanism of  claim 1 , further comprising a mechanical damping system coupled to the rod valve. 
     
     
         6 . The VVT mechanism of  claim 1 , wherein the intake valve comprises an air-intake valve of a Miller cycle combustion chamber. 
     
     
         7 . The VVT mechanism of  claim 1 , wherein the ECU further adjusts the length of the length-adjustable push rod to maintain the intake valve in an open position. 
     
     
         8 . The VVT mechanism of  claim 1 , wherein the operating condition of the engine system comprises one of a transient-state operation and steady-state operation, and wherein the ECU increases a length of the length-adjustable push rod in response to the engine system having the transient-state operation. 
     
     
         9 . A variable valve timing (VVT) mechanism comprising:
 a lever having a first end, a second end, and a fulcrum positioned therebetween;   a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever;   a mechanical damping system including:
 a fluid chamber positioned between the rod valve and the second end of the lever, the fluid chamber being fluidly connected to a fluid source, and 
 a fluid valve positioned between the fluid chamber and the fluid source; and 
   an engine control unit (ECU) operatively connected to the fluid valve, wherein the ECU adjusts a position of the fluid valve based on an operating condition of the engine system.   
     
     
         10 . The VVT mechanism of  claim 9 , further comprising an acoustic sensor operatively connected to the ECU, wherein the ECU is further configured to open the fluid valve in response to the acoustic sensor detecting a closing movement of the rod valve. 
     
     
         11 . The VVT mechanism of  claim 10 , wherein the operating condition of the engine system comprises one of a transient-state operation and steady-state operation, and wherein the ECU adjusts the position of the fluid valve in response to the engine system having the transient-state operation. 
     
     
         12 . The VVT mechanism of  claim 10 , wherein the ECU is further configured to open the fluid valve in response to detecting the closing movement of the rod valve, and wherein a cushioning fluid entering the fluid chamber from the fluid source reduces a closing speed of the rod valve. 
     
     
         13 . The VVT mechanism of  claim 9 , further comprising a length-adjustable push rod coupled to the first end of the lever and including an actuator therein. 
     
     
         14 . The VVT mechanism of  claim 9 , wherein the intake valve comprises an air-intake valve of a Miller cycle combustion chamber. 
     
     
         15 . A variable valve timing (VVT) mechanism comprising:
 a lever having a first end, a second end, and a fulcrum positioned therebetween;   a length-adjustable push rod coupled to the first end of the lever and including an actuator therein;   a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and   a mechanical damping system including:
 a fluid chamber positioned between the rod valve and the second end of the lever, the fluid chamber being fluidly connected to a fluid source, and 
 a fluid valve positioned between the fluid chamber and the fluid source; and 
   an engine control unit (ECU) operatively connected to the actuator and the fluid valve, wherein the ECU adjusts a length of the length-adjustable push rod and a position of the fluid valve based on an operating condition of an engine system including the intake valve therein.   
     
     
         16 . The VVT mechanism of  claim 15 , wherein the length-adjustable push rod further includes a first member and a second member each coupled to an opposing end of the actuator, and wherein one of the first member and the second member further includes a sleeve for receiving the actuator therein. 
     
     
         17 . The VVT mechanism of  claim 15 , further comprising:
 a spring positioned circumferentially about the rod valve, and interposed between the second end of the lever and the intake valve of the engine system; and   a position sensor operatively connected to the ECU, wherein the operating condition of the engine system includes a compression of the spring, and wherein the ECU adjusts a length of the length-adjustable push rod in response to the position sensor detecting a compression of the spring.   
     
     
         18 . The VVT mechanism of  claim 17 , further comprising a cam lobe coupled to the length-adjustable push rod, wherein the position sensor measures a position of the cam lobe to detect the compression of the spring. 
     
     
         19 . The VVT mechanism of  claim 15 , further comprising an acoustic sensor operatively connected to the ECU, wherein the ECU is further configured to open the fluid valve in response to detecting a closing movement of the rod valve. 
     
     
         20 . The VVT mechanism of  claim 15 , wherein the operating condition of the engine system comprises one of a transient-state operation and steady-state operation, and wherein the ECU increases a length of the length-adjustable push rod in response to the engine system having the transient-state operation.