Hydraulic variable valve lift apparatus

Abstract

A hydraulic pressure variable valve lift apparatus may include a housing that a piston chamber that one side thereof is opened is formed, a valve operating piston that is slidably disposed in the piston chamber and one end thereof is connected to a valve for opening/closing a port, and an EHV hydraulic pump that is configured to supply the piston chamber with oil, wherein a first oil passage is formed between the EHV hydraulic pump and the piston chamber on as to supply a side surface of the piston chamber with oil, and an orifice hole is formed from a piston side surface of the valve operating piston to a piston upper end surface. Accordingly, the valve lift amount can be varied according to the operating condition of the engine, a hydraulic pressure variable valve lift apparatus reduces an impact at a moment when the valve is closed by having a valve lift formed a ramp profile and does not require accurate process of multi orifice and thereby decreases a production cost.

1 . A hydraulic pressure variable valve lift apparatus comprising:
 a housing including one opened side and forming a piston chamber;   a valve operating piston slidably disposed in the piston chamber and one end thereof is connected to a valve for opening/closing a port; and   an EHV hydraulic pump configured to supply the piston chamber with oil,   wherein a first oil passage is formed between the EHV hydraulic pump and the piston chamber supplies a side surface of the piston chamber with oil, and an orifice hole is formed from a piston side surface of the valve operating piston to a piston upper end surface.   
     
     
         2 . The apparatus of  claim 1 , wherein one side of the first oil passage is connected to a hydraulic pressure line and a first check valve is disposed at the main oil passage to prevent the oil from being flown backward. 
     
     
         3 . The apparatus of  claim 1 , wherein a second oil passage diverging from the first oil passage and is connected to the piston chamber is formed and a second check valve is disposed at the second oil passage so as to prevent the oil from flowing backward. 
     
     
         4 . The apparatus of  claim 3 , wherein the second oil passage is connected to a chamber upper end surface of the piston chamber. 
     
     
         5 . The apparatus of  claim 3 , wherein the second oil passage is connected to the other side of the piston chamber corresponding to the first oil passage. 
     
     
         6 . The apparatus of  claim 5 , wherein the first oil passage is connected to a side surface of the piston chamber with at least L 1  from a chamber upper end surface of the piston chamber, the second oil passage is connected to a side surface of the piston chamber with at least L 2  from a chamber upper end surface of the piston chamber, and the length of the L 1  is longer than that of the L 2 . 
     
     
         7 . The apparatus of  claim 3 , wherein the second check valve includes a check ball for preventing back flowing and a check valve orifice is formed in the check ball such that little oil flows backward or forward. 
     
     
         8 . The apparatus of  claim 1 , wherein an orifice check valve is disposed at the orifice hole such that the oil flux supplied to the piston chamber through the orifice hole is limited and the supplied oil is prevented from being flowing backward. 
     
     
         9 . The apparatus of  claim 8 , wherein the orifice check valve includes a check ball for preventing back flowing and a check valve orifice is formed in the check ball such that small amount of oil flows backwards or forward. 
     
     
         10 . The apparatus of  claim 1 , wherein the first oil passage is connected to a hydraulic pressure release line, includes:
 an oil control valve is disposed at the hydraulic pressure release line to open/close the hydraulic pressure release line; and   an accumulator disposed at a downstream side of the oil control valve in the hydraulic pressure release line and temporarily storing the hydraulic pressure that is released.   
     
     
         11 . The apparatus of  claim 10 , wherein the accumulator includes an accumulator piston slidably disposed in the accumulator chamber formed in one side of the hydraulic pressure release line and an accumulator spring that elastically supports the accumulator piston.