A four-stroke internal combustion engine comprising an inlet cam configured to open and close an inlet valve, a No. 1 exhaust cam configured to open and close an exhaust valve, a No. 2 exhaust cam configured to open and close the same exhaust valve, wherein the No. 2 exhaust cam is angularly adjustable relative to the No. 1 exhaust cam in response to input from an operator, so that the No. 2 exhaust cam is able to be selectively engaged; wherein the No. 1 exhaust cam is configured to open and close the exhaust valve during the compression stroke, so that a selected quantity of air drawn in during the intake stroke is expelled during the compression stroke; and wherein the No. 2 exhaust cam is configured to optionally close the exhaust valve when engaged.

Methods and systems are provided for a valve lift control device. In one example, a method may include rotating an adjusting camshaft of the valve lift control device in order to adjust a valve lift of one or more cylinders.

The present disclosure relates to a variable valve drive for a lifting valve, in particular for a charge-exchange valve of an internal combustion engine, which is periodically movable between a closed position and an open position indirectly by way of a cam via a rocker lever. The variable valve drive includes a switchable rocker lever arrangement for the actuation of the lifting valve, having a transmission rocker lever and a valve rocker lever which are mounted pivotably on different rocker lever axles which are each parallel to the camshaft axis.

An engine variable valve train includes a cam changeover mechanism for axially shifting a cylindrical cam carrier fitted on and around a camshaft for changing over cam lobes on the cam carrier to cause one of the cam lobes to selectively act on an engine valve for engine operation. The cam changeover mechanism includes changeover pins adapted to be advanced and retracted for engagement with or disengagement from a lead groove formed around the cam carrier, and with a changeover driving shaft constituting a linear motion cam mechanism for causing the changeover pins to selectively advance to engage with the lead groove. The cam carrier, while rotating with the cam shaft, is axially shifted by the action of the lead groove having the changeover pins selectively engaged therewith, so that the cam lobes are changed over and one of the cam lobe is made to act on the engine valve.

The variable lift valve train includes a spring-loaded valve that is in mechanical connection with a lever bar. The lever bar is attached to a stroke limiter. The lever bar extends across the spring-loaded valve and the stroke limiter. The lever bar is positioned under a first cam. The angle of the first cam adjusts the angular orientation of the lever bar with respect to the stroke limiter as well as the spring-loaded valve. The stroke limiter is biased via a stroke spring. Moreover, the stroke limiter extends downwardly, and optionally engages against a stroke limiter cam. The stroke limiter cam is optionally able to influence the stroke limiter, and is a secondary influence when compared to the angular orientation of the lever bar. In use, the variable lift valve train is able to adjust the timing and lift of the spring-loaded valve of the engine.

Embodiments relate generally to energy storage systems, and in particular to energy storage systems using compressed gas as an energy storage medium. In various embodiments, a compressed gas storage system may include a plurality of stages to convert energy into compressed gas for storage, and then to recover that stored energy by gas expansion. In certain embodiments, a stage may comprise a reversible compressor/expander having a reciprocating piston. Pump designs for introducing liquid for heat exchange with the gas, are described. Gas flow valves featuring shroud and/or curtain portions, are also described.

A four-stroke internal combustion engine comprising an inlet cam configured to open and close an inlet valve, a No. 1 exhaust cam configured to open and close an exhaust valve, a No. 2 exhaust cam configured to open and close the same exhaust valve, wherein the No. 2 exhaust cam is angularly adjustable relative to the No. 1 exhaust cam in response to input from an operator, so that the No. 2 exhaust cam is able to be selectively engaged; wherein the No. 1 exhaust cam is configured to open and close the exhaust valve during the compression stroke, so that a selected quantity of air drawn in during the intake stroke is expelled during the compression stroke; and wherein the No. 2 exhaust cam is configured to optionally close the exhaust valve when engaged.

There is provided a variable valve device provided in a cylinder head and capable of changing a valve lift amount, including: a camshaft on which a plurality of cams with different valve lift amounts are formed; a switching mechanism configured to switch a cam for moving a valve among the plurality of cams; and an oil control valve configured to control an oil pressure for the switching mechanism. Oil starts to be supplied from the oil control valve to the switching mechanism at an end timing of a valve lift or in a zero range in which no valve lift occurs.

Internal combustion engines having a split crankshaft are disclosed. The engines may also have non-circular, preferably rectangular, cross-section pistons and cylinders. The pistons may include a skirt with a field of pockets that provide a ringless, non-lubricated, seal equivalent. The pistons also may have a domed piston head with depressions thereon to facilitate the movement of air/charge in the cylinder. The engines also may use multi-stage poppet valves in lieu of conventional poppet valves. The engines may use the pumping motion of the engine piston to supercharge the cylinder with air/charge. The engines also may operate in an inverted orientation in which the piston is closer to the local gravitationally dominant terrestrial body's center of gravity at top dead center position than at bottom dead center position.

A summation rocker system is disclosed for acting on the end of a stem of a poppet valve (16) in dependence upon the combined lifts of a first and a second cam profile defined by different cam lobes (14, 22) of a concentric camshaft (46). The system comprises a first rocker (12) mounted on a pivot shaft (18) and having a first follower (44) to contact the first cam profile and an end acting on the valve (16) to displace the valve (16) by an amount dependent upon the lift of the first cam profile, a rocker shaft (24) to be fixedly mounted on the engine, and a second rocker (20) pivotable about the rocker shaft (24), the second rocker (20) having a second follower (48) to contact the second cam profile and acting to displace the pivot shaft (18) of the first rocker (12) in dependence of the lift of second cam profile. The rocker shaft (24) intersects a plane containing the axis of the pivot shaft (18) and the end of the first rocker (12) acting on the valve stem, and the first rocker (12) includes a cut-out (26) for receiving the rocker shaft (24), which cut-out (26) is configured and dimensioned to prevent the rocker shaft (24) from interfering with movement of the first rocker (12).