A mechanical engine cylinder system, includes a cylinder, an occupying structure with a cavity, and a crankshaft piston, the cylinder having a dedicated compression space and a dedicated combustion space, the occupying structure having a primary combustion space utilized during an early stage of a power stroke, wherein combustion pressure applied to the crankshaft piston during the power stroke is applied to a smaller surface area of the crankshaft piston during an early stage of the power stroke and to a larger surface area of the crankshaft piston during a later stage of the power stroke, the combustion pressure applied to the occupying structure applies a net-force to the occupying structure in the direction of the crankshaft piston during the early stage of the power stroke, and in the opposite direction of the crankshaft piston during the later stage of the power stroke.

A mechanical engine cylinder system, includes a cylinder, an occupying structure with a cavity, and a crankshaft piston, the cylinder having a dedicated compression space and a dedicated combustion space, the occupying structure having a primary combustion space utilized during an early stage of a power stroke, wherein combustion pressure applied to the crankshaft piston during the power stroke is applied to a smaller surface area of the crankshaft piston during an early stage of the power stroke and to a larger surface area of the crankshaft piston during a later stage of the power stroke, the combustion pressure applied to the occupying structure applies a net-force to the occupying structure in the direction of the crankshaft piston during the early stage of the power stroke, and in the opposite direction of the crankshaft piston during the later stage of the power stroke.

A split cycle internal combustion engine includes a combustion cylinder accommodating a combustion piston and a compression cylinder accommodating a compression piston. The engine also includes a controller arranged to receive an indication of a parameter associated with the combustion cylinder and/or a fluid associated therewith and to control an exhaust valve of the combustion cylinder in dependence on the indicated parameter to cause the exhaust valve to close during the return stroke of the combustion piston, before the combustion piston has reached its top dead centre position (TDC), when the indicated parameter is less than a target value for the parameter; and close on completion of the return stroke of the combustion piston, as the combustion piston reaches its top dead centre position (TDC), when the indicated parameter is equal to or greater than the target value for the parameter.

A method for controlling an internal combustion engine system, the engine system including a combustor arranged to receive air and fuel, and combust the received air and fuel, an expander arranged to expand exhaust gases from the combustion in the combustor and to extract energy from the expanded exhaust gases, and a communication valve arranged to control a communication between the combustor and the expander, including determining during operation of the engine system whether there is a pressure difference across said communication valve.

A method for controlling an internal combustion engine system, the engine system including a combustor arranged to receive air and fuel, and combust the received air and fuel, an expander arranged to expand exhaust gases from the combustion in the combustor and to extract energy from the expanded exhaust gases, and a communication valve arranged to control a communication between the combustor and the expander, including determining during operation of the engine system whether there is a pressure difference across said communication valve.

The invention relates to an internal combustion engine comprising a combustion cylinder housing a combustion piston, a compressor cylinder housing a compressor piston, an expander cylinder housing an expander piston, and a crankshaft connected to the combustion piston and the expander piston by a respective connecting rod. The internal combustion engine further comprises a connecting element rigidly connecting the compressor piston and the expander piston such that the compressor piston and the expander piston move in unison.

The invention relates to an internal combustion engine comprising a combustion cylinder housing a combustion piston, a compressor cylinder housing a compressor piston, an expander cylinder housing an expander piston, and a crankshaft connected to the combustion piston and the expander piston by a respective connecting rod. The internal combustion engine further comprises a connecting element rigidly connecting the compressor piston and the expander piston such that the compressor piston and the expander piston move in unison.

It is disclosed a boxer engine with two substantially mirror-symmetric engine sides (L, R) comprising a crankshaft (1) to which is connected, at least two main scotch yoke assemblies (110) each having one main piston (7) arranged inside one main cylinder (I, III; II, IV) of each engine side (R; L), and at least one auxiliary scotch yoke assembly (120) having a pair of auxiliary pistons (8) arranged inside a pair of auxiliary cylinders (V, VII; VI, VIII) of each engine side (R; L), wherein the main scotch yoke assemblies (110) are arranged synchronized on the crankshaft (1) and the at least one auxiliary scotch yoke assembly (120) is arranged 180° offset on the crankshaft (1), each auxiliary piston (7) defining an outer space and an inner space within each auxiliary cylinder (V, VII; VI, VIII), the inner space facing the opposite engine side (R; L), wherein, said inner spaces of each auxiliary cylinder (V, VII; VI, VIII) pair are in fluid communication and forming a compression chamber, said compression chamber comprises first and second check valves (69, 70), wherein the auxiliary cylinder (V, VII; VI, VIII) pair is adapted to suck in ambient air through the first check valve (69) and compress and pump said air out through the second check valve (70) into a main cylinder (I, III; II, IV) of the opposite engine side (R; L), and said outer spaces of each auxiliary cylinder (V, VII; VI, VIII) pair are in fluid communication and are receiving pressurized exhaust gas from a main cylinder (I, III; II, IV) of the same engine side (R; L).

The present invention relates to an internal combustion engine arrangement for a vehicle, said internal combustion engine arrangement comprising a combustion cylinder housing a reciprocating combustion piston, and an expansion cylinder housing a reciprocating expansion piston, said expansion cylinder being arranged in downstream fluid communication with the combustion cylinder for receiving combustion gases exhausted from the combustion cylinder, wherein the internal combustion engine arrangement further comprises a pressure tank arranged in fluid communication with the expansion cylinder, wherein the internal combustion engine arrangement is further arranged to be operated in a first operating mode in which compressed gas generated in the expansion cylinder is delivered to the pressure tank, and a second operating mode in which compressed gas contained in the pressure tank is delivered from the pressure tank to the expansion cylinder.

The present invention relates to an internal combustion engine arrangement for a vehicle, said internal combustion engine arrangement comprising a combustion cylinder housing a reciprocating combustion piston, and an expansion cylinder housing a reciprocating expansion piston, said expansion cylinder being arranged in downstream fluid communication with the combustion cylinder for receiving combustion gases exhausted from the combustion cylinder, wherein the internal combustion engine arrangement further comprises a pressure tank arranged in fluid communication with the expansion cylinder, wherein the internal combustion engine arrangement is further arranged to be operated in a first operating mode in which compressed gas generated in the expansion cylinder is delivered to the pressure tank, and a second operating mode in which compressed gas contained in the pressure tank is delivered from the pressure tank to the expansion cylinder.