Methods of controlling a camless engine to prevent interference between valves and pistons

Abstract

Methods of controlling a camless engine to prevent interference between engine valves and engine valves and pistons. The methods utilize one or more safe trajectories for the valves versus engine crankshaft angle. In normal operation, an engine valve control system monitors crankshaft angle and controls the engine valve so as to stay on the safe side of a safe trajectory. In the event the actual valve motion deviates excessively from the intended trajectory so as to reach or cross the safe trajectory, preventive action is taken, typically to command the engine valve to close. Safe trajectories may be stored in lookup tables, in equation form or both. In some cases a single safe trajectory for a valve may be sufficient, though in other cases, safe trajectories as a function of some engine operating conditions and environmental conditions, and in some cases may include crankshaft acceleration. Various embodiments are disclosed.

What is claimed is:  
     
         1 . A method of operating a camless engine valve actuation system in an internal combustion engine, the system including one or more actuators controlled by a controller operating under program control to control an engine valve, comprising: 
 determining a safe trajectory for the engine valve versus crankshaft angle, the safe trajectory separating acceptable trajectories from unacceptable trajectories risking or causing collision of the engine valve another engine valve or with the engine piston;    determining the desired trajectory for the engine valve versus crank angle;    controlling the actuators to nominally cause the engine valve to follow the desired trajectory;    sensing the actual engine valve trajectory, and if the actual engine valve trajectory deviates into an unacceptable trajectory, controlling the actuators to close the engine valve.    
     
     
         2 . The method of  claim 1  further comprising, if the actual engine valve trajectory deviates from the desired trajectory more than an allowable deviation within the acceptable trajectories, controlling to actuators to reduce the deviation.  
     
     
         3 . The method of  claim 1  wherein the desired trajectory for the engine valve versus crank angle is determined as a desired opening angle, a desired opening flank rate, a desired lift, a desired closing flank rate and a desired closing angle.  
     
     
         4 . The method of  claim 1  wherein the control of the actuators to nominally cause the engine valve to follow the desired trajectory is based in part on previous actuator controls and associated engine valve responses.  
     
     
         5 . The method of  claim 1  wherein the safe trajectory for an intake valve is comprised of a minimum opening angle and a maximum allowable opening flank rate.  
     
     
         6 . The method of  claim 1  wherein the safe trajectory for an exhaust valve is comprised of a maximum allowable closing angle and a minimum allowable closing flank rate.  
     
     
         7 . The method of  claim 1  wherein the safe trajectory for an exhaust valve is comprised of a minimum allowable opening angle and a maximum allowable opening flank rate.  
     
     
         8 . The method of  claim 1  wherein a safe trajectory is determined based on engine operating conditions and environmental conditions.  
     
     
         9 . The method of  claim 8  wherein a safe trajectory is determined based on past, current and commanded engine load.  
     
     
         10 . The method of  claim 1  wherein a desired trajectory is determined based on engine operating conditions and environmental conditions.  
     
     
         11 . The method of  claim 10  wherein a desired trajectory is determined based on past, current and commanded engine load.  
     
     
         12 . The method of  claim 10  wherein the desired trajectory for the engine valve is determined, at least in part, from equations.  
     
     
         13 . The method of  claim 10  wherein the desired trajectory for the engine valve is determined, at least in part, from lookup tables.  
     
     
         14 . The method of  claim 1  wherein the safe trajectory for the engine valve is determined, at least in part, from equations.  
     
     
         15 . The method of  claim 1  wherein the safe trajectory for the engine valve is determined, at least in part, from lookup tables.  
     
     
         16 . The method of  claim 1  wherein the actuators comprise a hydraulic actuator controlled by electronically controlled valving.  
     
     
         17 . The method of  claim 16  wherein the hydraulic actuator is a single stage hydraulic actuator.  
     
     
         18 . The method of  claim 17  wherein the hydraulic actuator is a two stage hydraulic actuator.  
     
     
         19 . The method of  claim 18  wherein a first stage comprises electromagnetically actuated spool valving, and the second state comprises hydraulically controlled spool valving.  
     
     
         20 . A method of operating a camless engine valve actuation system in an internal combustion engine, the system including one or more actuators controlled by a controller operating under program control to control an engine valve, comprising: 
 determining a safe trajectory for the engine valve versus crankshaft angle, the safe trajectory separating acceptable trajectories from unacceptable trajectories risking or causing collision of the engine valve with another engine valve or with the engine piston;    determining the desired trajectory for the engine valve versus crank angle;    controlling the actuators to nominally cause the engine valve to follow the desired trajectory;    sensing the actual engine valve trajectory, and;    if the actual engine valve trajectory deviates from the desired trajectory by more than an allowable deviation, controlling to actuators to reduce the deviation;    if the actual engine valve trajectory deviates from the desired trajectory into an unacceptable trajectory, controlling the actuators to close the engine valve.    
     
     
         21 . The method of  claim 20  wherein the desired trajectory for the engine valve versus crank angle is determined as a desired opening angle, a desired opening flank rate, a desired lift, a desired closing flank rate and a desired closing angle.  
     
     
         22 . The method of  claim 20  wherein the control of the actuators to nominally cause the engine valve to follow the desired trajectory is based in part on previous actuator controls and associated engine valve responses.  
     
     
         23 . The method of  claim 20  wherein the safe trajectory for an intake valve is comprised of a minimum opening angle and a maximum allowable opening flank rate.  
     
     
         24 . The method of  claim 20  wherein the safe trajectory for an exhaust valve is comprised of a maximum allowable closing angle and a minimum allowable closing flank rate.  
     
     
         25 . The method of  claim 20  wherein the safe trajectory for an exhaust valve is comprised of a minimum allowable opening angle and a maximum allowable opening flank rate.  
     
     
         26 . The method of  claim 20  wherein a safe trajectory is determined based on engine operating conditions and environmental conditions.  
     
     
         27 . The method of  claim 26  wherein a safe trajectory is determined based on past, current and commanded engine load.  
     
     
         28 . The method of  claim 20  wherein a desired trajectory is determined based on engine operating conditions and environmental conditions.  
     
     
         29 . The method of  claim 28  wherein a desired trajectory is determined based on past, current and commanded engine load.  
     
     
         30 . The method of  claim 28  wherein the desired trajectory for the engine valve is determined, at least in part, from equations.  
     
     
         31 . The method of  claim 28  wherein the desired trajectory for the engine valve is determined, at least in part, from lookup tables.  
     
     
         32 . The method of  claim 20  wherein the safe trajectory for the engine valve is determined, at least in part, from equations.  
     
     
         33 . The method of  claim 20  wherein the safe trajectory for the engine valve is determined, at least in part, from lookup tables.  
     
     
         34 . The method of  claim 20  wherein the actuators comprise a hydraulic actuator controlled by electronically controlled valving.  
     
     
         35 . The method of  claim 34  wherein the hydraulic actuator is a two stage hydraulic actuator.  
     
     
         36 . The method of  claim 35  wherein a first stage comprises electromagnetically actuated spool valving, and the second state comprises hydraulically controlled spool valving.