A piston is provided for an internal combustion engine. The piston may include a cylindrical first piston portion having a first diameter, a cylindrical second piston portion of the first diameter, and a cylindrical third piston portion of a second diameter less than the first diameter located between the first piston portion and the second piston portion. The first piston portion may be configured such that prior to assembly, the first piston portion is separate from the second piston portion. The piston may also include a continuous, gapless piston ring circumscribing the third piston portion, where the piston ring may be configured such that when heated the piston ring deforms in an axial direction of the piston.

A fan is suitable for an air-guiding system of an outboard motor including an internal combustion engine and a covering hood bounding an engine interior space. The engine drives the fan, which is connected to an upright shaft journal projecting beyond an upper side of a housing of the engine. The covering hood has air flow openings, and the fan influences the air flows in the covering hood interior space. A flywheel, fixedly attached to the upright shaft journal, carries a fan wheel of the fan. The fan wheel is set in place from above, and the flywheel carries the fan wheel for conjoint rotation. Airflows enter the interior space via an inlet opening and a first conducting device, and the airflows, under the action of the fan, act upon at least parts of surfaces of the internal combustion engine and the auxiliary units to cool the internal combustion engine.

An axis line of a cylinder and a cylinder head of a four-stroke engine is disposed inclining to one side in a lateral direction with respect to a center line extending in a front-rear direction of the outboard motor from a top view, and a fuel tank is disposed on a side portion of the cylinder and the cylinder head in another side in the lateral direction with respect to the center line.

A marine vessel engine in which moving parts found in conventional marine engines are eliminated, wherein such engine is used for the propulsion of marine vessels. In the marine vessel engine, no lubrication or cooling is required, and a column of water replaces the conventional piston in a cylinder of the engine, wherein such water column partially fills such cylinder. The marine vessel engine comprises a cylinder, a bent tube with a plurality of openings and two ends, a flapping member, at least one solenoid valve, and an exhaust. In operation of the marine vessel engine, a column of water fills the cylinder through the bent tube openings, and is purged outside from the cylinder through the flapping member. The at least one solenoid valve controls the flow of a power source into the cylinder.

A method of operating an internal combustion engine having a housing, a piston mounted in the housing for complex motion about a plurality of axes and coupled to a shaft, and wherein occur phases of compression, combustion, and expansion in the housing, and wherein, in the compression phase, air introduced through an intake port into the housing is compressed by reducing volume of a compression chamber in the housing from an initial volume to a second volume that is less than the initial volume, and in the expansion phase, byproducts of combustion expand from the second volume to a third volume that is greater than the initial volume.

A method of operating an internal combustion engine having a housing, a piston mounted in the housing for complex motion about a plurality of axes and coupled to a shaft, and wherein occur phases of compression, combustion, and expansion in the housing, and wherein, in the compression phase, air introduced through an intake port into the housing is compressed by reducing volume of a compression chamber in the housing from an initial volume to a second volume that is less than the initial volume, and in the expansion phase, byproducts of combustion expand from the second volume to a third volume that is greater than the initial volume.

A variable compression ratio internal combustion engine is provided with a variable compression ratio mechanism in which a mechanical compression ratio of the internal combustion engine changes in accordance with a rotational position of a control shaft, a low compression ratio side stopper, a high compression ratio side stopper, a sensor for detecting a rotational position of a drive shaft of an actuator, and an arm press-fitted onto the drive shaft. Relative rotation between the arm and the drive shaft occurs when a torque exceeding an upper-limit torque has been applied. The drive shaft or the control shaft is caused to move to restriction positions restricted by the respective stoppers, and then a diagnosis on the presence or absence of the relative rotation is executed, based on the detected values at the respective restriction positions.

A variable compression ratio internal combustion engine is provided with a variable compression ratio mechanism in which a mechanical compression ratio of the internal combustion engine changes in accordance with a rotational position of a control shaft, a low compression ratio side stopper, a high compression ratio side stopper, a sensor for detecting a rotational position of a drive shaft of an actuator, and an arm press-fitted onto the drive shaft. Relative rotation between the arm and the drive shaft occurs when a torque exceeding an upper-limit torque has been applied. The drive shaft or the control shaft is caused to move to restriction positions restricted by the respective stoppers, and then a diagnosis on the presence or absence of the relative rotation is executed, based on the detected values at the respective restriction positions.

A multi-cylinder engine includes a plurality of cylinders that are fired at uneven intervals. A controller is configured or programmed to overlap a time period that a plunger increases a pressure in a pressurizing chamber and a time period that an electromagnetic valve remains opened in at least the longest one of the intervals at which the firing is conducted in the plurality of cylinders.

The present invention discloses a two-dimensional engine, including a driving device, a two-dimensional gas compressor, a gas outlet pipe, a refueling device, a safety device, an electric ignition device, an axial-flow gas compressor, and a crank connecting rod mechanism, wherein the electric ignition device is arranged on a left side of the gas outlet pipe; the crank connecting rod mechanism is arranged below the gas outlet pipe; the driving device includes a first motor, a first gear, a first dowel bar and a first rack that is arranged on the first dowel bar; the first rack is meshed with the first gear; and the two-dimensional gas compressor includes an upper pressure plate, a first cylindrical plate, a second cylindrical plate, a fixing rod, a first pressure-bearing plate, a second pressure-bearing plate and a shell. The present invention has the beneficial effects of simple structure and relatively high energy utilization rate.