Variable lost motion valve actuator and method

Abstract

A lost motion engine valve actuation system and method of actuating an engine valve are disclosed. The system may comprise a valve train element, a pivoting lever, a control piston, and a hydraulic circuit. The pivoting lever may include a first end for contacting the control piston, a second end for transmitting motion to a valve stem and a means for contacting a valve train element. The amount of lost motion provided by the system may be selected by varying the position of the control piston relative to the pivoting lever. Variation of the control piston position may be carried out by placing the control piston in hydraulic communication with a control trigger valve and one or more accumulators. Actuation of the trigger valve releases hydraulic fluid allowing for adjustment of the control piston position. Means for limiting valve seating velocity, filling the hydraulic circuit upon engine start up, and mechanically locking the control piston/lever for a fixed level of valve actuation are also disclosed.

What is claimed is: 
     
         1 . A valve actuation system for controlling the operation of an engine valve, said system comprising: a hydraulic lost motion system having a master piston disposed in a master piston chamber, a slave piston disposed in a slave piston chamber, and a hydraulic circuit connecting the master piston chamber to the slave piston chamber; a solenoid actuated valve in hydraulic communication with the hydraulic circuit; and means for determining solenoid actuation and deactuation times based on a selected engine mode, and engine load and engine speed values. 
     
     
         2 . The system of  claim 1 , wherein the means for determining includes an electronic storage device having solenoid actuation and deactuation times for an engine warm-up mode and a normal positive power mode. 
     
     
         3 . The system of  claim 1 , wherein the means for determining includes an electronic storage device having solenoid actuation and deactuation times for an engine warm-up mode, a normal positive power mode, a transient mode, and an engine braking mode of operation. 
     
     
         4 . The system of  claim 1 , wherein the means for determining solenoid actuation and deactuation times determines such times based further on an engine oil temperature value. 
     
     
         5 . The system of  claim 1 , wherein the means for determining solenoid actuation and deactuation times determines such times based further on an engine oil viscosity value. 
     
     
         6 . The system of  claim 1 , wherein the means for determining solenoid actuation and deactuation times changes a number of cylinders in which engine valves are actuated based on an engine load value. 
     
     
         7 . The system of  claim 6 , wherein the means for determining solenoid actuation and deactuation times rotates the selection of cylinders in which engine valves are actuated when less than all cylinders have actuated engine valves. 
     
     
         8 . The system of  claim 1 , wherein the means for determining solenoid actuation and deactuation times changes a number of cylinders in which engine valves are actuated based on the persistence of an engine load value over a preselected time period. 
     
     
         9 . The system of  claim 1 , wherein the means for determining solenoid actuation and deactuation times includes an electronic storage device having solenoid actuation and deactuation times for a reduced sound pressure level mode of engine braking operation. 
     
     
         10 . The system of  claim 1 , further comprising: means for determining a present temperature of an engine fluid, wherein the means for determining solenoid actuation and deactuation times determines such times based on a determined engine fluid temperature. 
     
     
         11 . The system of  claim 1 , further comprising: means for determining a present viscosity of an engine fluid, wherein the means for determining solenoid actuation and deactuation times determines such times based on a determined engine fluid viscosity. 
     
     
         12 . The system of  claim 1 , further comprising: means for determining a present temperature of an engine fluid; means for determining a present viscosity of an engine fluid, wherein the means for determining solenoid actuation and deactuation times determines such times based on determined engine fluid temperature and viscosity. 
     
     
         13 . A valve actuation system for controlling the operation of an engine valve which controls communication between an engine cylinder and an engine manifold, said system comprising: a hydraulic lost motion system having a master piston disposed in a master piston chamber, a slave piston disposed in a slave piston chamber, and a hydraulic circuit connecting the master piston chamber to the slave piston chamber; a valve in hydraulic communication with the hydraulic circuit; and means for determining valve actuation and deactuation times based on a value selected from the group consisting of an engine fluid temperature value and an engine fluid viscosity value. 
     
     
         14 . The system of  claim 13 , wherein the means for determining includes an electronic storage device having valve actuation and deactuation times for an engine warm-up mode and a normal positive power mode. 
     
     
         15 . The system of  claim 13 , wherein the means for determining includes an electronic storage device having valve actuation and deactuation times for an engine warm-up mode, a normal positive power mode, a transient mode, and an engine braking mode of operation. 
     
     
         16 . The system of  claim 13 , wherein the means for determining valve actuation and deactuation times changes a number of cylinders in which engine valves are actuated based on an engine load value. 
     
     
         17 . The system of  claim 16 , wherein the means for determining valve actuation and deactuation times rotates the selection of cylinders in which engine valves are actuated when less than all cylinders have actuated engine valves. 
     
     
         18 . The system of  claim 13 , wherein the valve in hydraulic communication with the hydraulic circuit is a solenoid actuated valve. 
     
     
         19 . A hydraulic valve actuation system for controlling, at different operating temperatures, the operation of at least one engine valve which engine valve controls communication between an engine cylinder and an engine manifold, said valve actuation system including a solenoid actuated valve adapted to control hydraulic fluid flow in the valve actuation system, and said valve actuation system comprising: a solenoid; a solenoid actuated valve; means for determining a present temperature of an engine fluid; means for modifying the operation of the solenoid or solenoid actuated valve in response to the determined temperature; and a hydraulic lost motion system having a master piston disposed in a master piston chamber, a slave piston disposed in a slave piston chamber, and a hydraulic circuit connecting the master piston chamber to the slave piston chamber, said hydraulic lost motion system being in hydraulic communication with said solenoid actuated valve. 
     
     
         20 . The valve actuation system of  claim 19 , wherein the means for modifying compares a determined present temperature with predetermined values to determine a timing modification for solenoid actuation.