A valve drive for an internal combustion engine may include a camshaft, at least one cam follower, at least one adjusting device, and at least one control shaft. The camshaft may include at least one cam group including a first cam and a second cam. The at least one adjusting device may include a first engagement element and a second engagement element. The at least one control shaft may include at least one control cam group including a first control cam and a second control cam. The at least one control shaft may rotate such that at least one stop region of the first control cam adjusts the first engagement element from the basic position into the switching position and at least one stop region of the second control cam adjusts the second engagement element from the basic position into the switching position one after the other.

A scavenger valve and method of directing gas in a two stroke engine are provided involving poppet elements in a scavenger valve with specific multiple, different flow paths from individual poppet heads.

A scavenger valve and method of directing gas in a two stroke engine are provided involving poppet elements in a scavenger valve with specific multiple, different flow paths from individual poppet heads.

A method for cleaning an exhaust valve of a two-stroke internal combustion engine is provided. The method comprises: requesting an exhaust valve cleaning cycle if at least one of a first condition or a second condition is satisfied; initiating the exhaust valve cleaning cycle if at least one of a third condition or a fourth condition is satisfied; and aborting the exhaust valve cleaning cycle if at least one of the at least one of the third or fourth conditions is no longer satisfied. The first condition is a time elapsed since a previous cleaning cycle has been completed being greater than a predetermined time. The second condition is a rate of opening of the exhaust valve being less than predetermined rate. The third condition is a throttle valve being closed. The fourth condition is an engine speed being less than a predetermined engine speed.

A method for cleaning an exhaust valve of a two-stroke internal combustion engine is provided. The method comprises: requesting an exhaust valve cleaning cycle if at least one of a first condition or a second condition is satisfied; initiating the exhaust valve cleaning cycle if at least one of a third condition or a fourth condition is satisfied; and aborting the exhaust valve cleaning cycle if at least one of the at least one of the third or fourth conditions is no longer satisfied. The first condition is a time elapsed since a previous cleaning cycle has been completed being greater than a predetermined time. The second condition is a rate of opening of the exhaust valve being less than predetermined rate. The third condition is a throttle valve being closed. The fourth condition is an engine speed being less than a predetermined engine speed.

A multicylinder internal combustion free-piston engine (FPE) with synchronized reciprocating plungers. The invention provides a solution for the problem of the slow engine speed typical of FPE's with heavy plunger mass. Bounce chambers fitted with sleeve valves control the engine's speed and stroke length. The invention's configuration prevents piston head-strikes and operates at standard compression ratios. Piston pop-top intake valves allow uniflow scavenging and connecting rod oil channels provide lubrication with no combustion chamber contamination. Poppet combustion head valves are operated by linear cams attached to the plungers. Hydraulic valve actuators implement variable valve timing under computer control.

A multicylinder internal combustion free-piston engine (FPE) with synchronized reciprocating plungers. The invention provides a solution for the problem of the slow engine speed typical of FPE's with heavy plunger mass. Bounce chambers fitted with sleeve valves control the engine's speed and stroke length. The invention's configuration prevents piston head-strikes and operates at standard compression ratios. Piston pop-top intake valves allow uniflow scavenging and connecting rod oil channels provide lubrication with no combustion chamber contamination. Poppet combustion head valves are operated by linear cams attached to the plungers. Hydraulic valve actuators implement variable valve timing under computer control.

A multicylinder internal combustion free-piston engine (FPE) with synchronized reciprocating plungers. The invention provides a solution for the problem of the slow engine speed typical of FPE's with heavy plunger mass. Bounce chambers fitted with sleeve valves control the engine's speed and stroke length. The invention's configuration prevents piston head-strikes and operates at standard compression ratios. Piston pop-top intake valves allow uniflow scavenging and connecting rod oil channels provide lubrication with no combustion chamber contamination. Poppet combustion head valves are operated by linear cams attached to the plungers. Hydraulic valve actuators implement variable valve timing under computer control.

A multicylinder internal combustion free-piston engine (FPE) with synchronized reciprocating plungers. The invention provides a solution for the problem of the slow engine speed typical of FPE's with heavy plunger mass. Bounce chambers fitted with sleeve valves control the engine's speed and stroke length. The invention's configuration prevents piston head-strikes and operates at standard compression ratios. Piston pop-top intake valves allow uniflow scavenging and connecting rod oil channels provide lubrication with no combustion chamber contamination. Poppet combustion head valves are operated by linear cams attached to the plungers. Hydraulic valve actuators implement variable valve timing under computer control.

A method of controlling a reciprocating internal combustion engine comprising: a cylinder defining a cavity having a first end and a second end; and a piston moveable within the cavity of the cylinder between the first end and the second end, the method comprising: receiving at least a first signal; determining a quantity of liquid air to be injected using at least the received first signal; controlling injection of the determined quantity of liquid air into the first end of the cavity at a first time when the piston is closer to the first end than the second end.