689 results about "Four-stroke engine" patented technology

An engine has a crankshaft, rotating about a crankshaft axis of the engine. An expansion piston is slidably received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston reciprocates through an expansion stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft. A ratio of cylinder volumes from BDC to TDC for either one of the expansion cylinder and compression cylinder is substantially 20 to 1 or greater.

A system and method to control engine valve timing to during the start of an internal combustion engine. Electromechanical valves are controlled in a manner to reduce engine vibration and hydrocarbon emissions during the start of an internal combustion engine. The method controls valves without an explicit four-stroke engine cycle during a start.

An engine control apparatus is disclosed for determining crankshaft position and engine phase of an internal combustion engine (10) through monitoring intake air pressure fluctuations (120). The opening of the intake valve (44) is mechanically linked to the crankshaft position of an engine. When the intake valve (44) opens it creates air pressure fluctuations in the air induction system (14) of the engine (10). The control apparatus is configured to determine intake air pressure fluctuations indicative of an intake air event (100 to 110) and thus a particular crankshaft position, and their corresponding period of the engine cycle. The controller then uses this information to determine crankshaft speed and position for the purpose of fuel injection and ignition timing of the internal combustion engine. Engine phase is also determined on four-stroke engines. The engine may also include a crankshaft position sensor in combination with monitoring intake air pressure fluctuations to increase resolution in determination of crankshaft position.

An engine includes a crankshaft, rotating about a crankshaft axis of the engine. A power piston is slidably received within a first cylinder and is operatively connected to the crankshaft via first linkage system. The power piston reciprocates through a power stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft. A compression piston is slidably received within a second cylinder and operatively connected to the crankshaft via second linkage system. The first and second linkage systems share no common mechanical link. The compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same revolution of the crankshaft. The power piston leads the compression piston by a phase shift angle that is substantially equal to or greater than zero degrees and less than 30 degrees.

A lubrication system for a small lightweight four-stroke engine is disclosed. The lubrication system, provided with a weight at one end of a flexible oil tube inserted into an oil reservoir, is capable of providing a sufficient lubrication to components of the engine which may operate in a horizontal posture, a vertical posture, or any posture therebetween.

An engine is disclosed which may operate in a first operating state wherein a spark ignited fuel is ignited in a combustion chamber with an igniter and a second operating state wherein a compression ignited fuel is ignited in a combustion chamber with an igniter. A compression ratio in the combustion chamber being up to about eight to one. The engine may be a four-stroke engine. The engine may include a piston having a top portion with a recessed central portion.

A two stroke cycle internal combustion engine machine that does not require lubricating oil to be mixed with its fuel, producing greater efficiency, higher power to weight ratio, cooler operating temperatures, a wider speed range, greater simplicity, and lower toxic emissions, many of the improvements also transferable to four stroke engines.

The invention relates a two-stroke internal combustion engine (10) comprising at least one cylinder (20) with a piston (24) arranged reciprocateably between its top dead center and bottom dead center, and a cylinder cover (26) defining a combustion chamber (22), oxygen containing gas inlet (18) in the lower part of the cylinder (20) to be open into the combustion chamber (22) at least while the piston is at its bottom dead center position, a gaseous fuel inlet (30) arranged in the cylinder between the oxygen containing gas inlet (18) and the cylinder cover(26), and an exhaust valve (28) arranged to the cylinder cover at a center axis of the cylinder. The cylinder cover(26) is provided with pilot ignition pre-chambers (36) opening into the combustion chamber (22) through pre-chamber ports (34).The preset invention relates also to method of operating the two-stroke engine (10).

The interior of a crankcase is divided into a front crank chamber and a rear transmission chamber by a partition wall of a given height. A lower part of the transmission case is used as an oil reservoir chamber for reserving lubricating oil. Opposite ends of the crankcase are covered with covers to form a generator chamber and a clutch chamber. The crank chamber is connected to the generator chamber by a drain passage to drain oil collected in the crank chamber into the generator chamber. A scavenging pump placed in the clutch chamber sucks the oil collected in the generator chamber through an oil passage extending across the crankcase under the crank chamber and discharges the oil into an air space in the clutch chamber.

An engine control apparatus is disclosed for determining crankshaft position and engine phase of an internal combustion engine through monitoring intake air pressure fluctuations. The opening of the intake valve is mechanically linked to the crankshaft position of an engine. When the intake valve opens it creates air pressure fluctuations in the air induction system of the engine. The control apparatus is configured to determine intake air pressure fluctuations indicative of an intake air event and thus a particular crankshaft position, and their corresponding period of the engine cycle. The controller then uses this information to determine crankshaft speed and position for the purpose of fuel injection and ignition timing of the internal combustion engine. Engine phase is also determined on four-stroke engines. The engine may also include a crankshaft position sensor in combination with monitoring intake air pressure fluctuations to increase resolution in determination of crankshaft position. A circuit is provided for simultaneously measuring intake temperature using a single bridge type pressure sensor in order to calculate air mass flow rate.

A four-stroke engine (1) structured to introduce fresh air and EGR gas into a cylinder (1a) includes a blowdown supercharging system (40) using a combustion chamber internal pressure when exhaust valves open in an expansion stroke of a first cylinder (hereinafter denoted as an exhaust blowdown pressure) for introducing EGR gas into a second cylinder from near a bottom dead center of an intake stroke to near a bottom dead center of a compression stroke of the second cylinder which is different from the first cylinder in combustion timing, and a secondary air supply system (20) supplying secondary air to an exhaust port (1e) of the second cylinder prior to arrival of the exhaust blowdown pressure at the second cylinder. The secondary air in the exhaust port and the EGR gas are supercharged into the second cylinder by the exhaust blowdown pressure from the first cylinder.

A method for combusting fuel in an engine involving decreasing a first volume of gas to a second volume, in two stages, while increasing the pressure and temperature of that volume of gas (a compression process having a chosen compression ratio), then increasing the second volume to a third volume at constant pressure while adding heat until a predetermined temperature is obtained, increasing the third volume of gas to a fourth volume, in two stages while decreasing the pressure at the predetermined temperature (an expansion process having a chosen expansion ratio much greater than the compression ratio), decreasing the pressure to atmospheric pressure while removing heat under constant volume, and finally decreasing the volume of gas to the first volume while removing heat under constant pressure to complete an over expanded, limited-temperature cycle. Also disclosed is an engine employing said over expanded, limited-temperature cycle.

A snowmobile has a four-stroke engine mounted in an engine cradle and an exhaust system connected to the engine. The exhaust system includes a generally U-shaped exhaust pipe extending forwardly from the engine to a first point disposed forwardly of the engine cradle, and of suspension assemblies of the skis, and extending rearwardly from the first point to a second point disposed rearwardly of a front of the engine cradle.

The fuel efficiency of an internal combustion reciprocating piston engine may be increased through selective secondary expansion of exhaust gas in the engine cylinders in order to recover exhaust gas energy which is otherwise wasted by cylinder blow-down at the end of the power stroke. Exhaust valve cam switching, intake valve deactivation, multiple exhaust valves, a specialized exhaust manifold arrangement and an exhaust gas diverter valve can be configured to enable a reciprocating engine to selectively operate in efficient eight stroke cycle compound mode when moderate engine power is demanded, then revert to conventional four stroke cycle non-compound mode operation when high engine power is demanded, without stopping the engine. For a road vehicle application, the benefit is substantially reduced highway cruising fuel consumption, while incurring minimal impact on engine weight, minimal impact on engine manufacturing cost, and no adverse impact on vehicle acceleration performance, hill climbing performance or trailer towing performance.

A four-stroke internal combustion engine includes a crankcase with a bottom, an oil pan and an oil spray generating assembly. The oil spray generating assembly having a closed sidewall, a valve, a bottom cap and nozzles is attached to the bottom of the crankcase and is enclosed by the oil pan. The closed sidewall is formed at the bottom of the crankcase to define a mist chamber enclosed by the bottom cap. The valve is mounted in the mist chamber with a valve port defined through the crankcase and a resilient valve flap corresponding to the valve port attached to the bottom of the crankcase. The nozzles are respectively mounted in the bottom cap out of the mist chamber inside the closed sidewall. The operation of the engine will produce an oil vapor for lubrication with the lubricating oil flowing out of the nozzles.

Providing a cam for lifting and lowering the exhaust valve so that the exhaust gas return-flow from one cylinder to another cylinder can be realized as greatly as possible, wherein the pistons and the exhaust valves do not come in contact with each other, and the valve control method does not depend on an electronic control approach. An exhaust cam for lifting and lowering the valve lift of the exhaust valve of one of the cylinders wherein the cam profile of the exhaust cam regarding the one of the cylinders including, but not limited to: a main exhaust lobe part for opening the exhaust valve so that the exhaust gas is discharged out of the cylinder; and, a gas return lobe part for opening the exhaust valve so that the quantity of the exhaust gas from the one of cylinders to the other cylinder is increased, the gas return lobe part being formed on the cam-follower descending part of the profile so as to delay the closing timing of the exhaust valve or maintain the valve lift-displacement regarding the exhaust valve larger, and wherein the cam profile is formed so that the interference between the exhaust valve and the piston is evaded and the overlap regarding the exhaust valve of the one cylinder and the exhaust valve of the other cylinder is increased by the manner that the main exhaust lobe part and the gas return lobe part rise outward from the base circle.

A rotary modulation engine enabling modulation of rotary pistons' rotational speeds is introduced. The rotary modulation engine utilizes four elliptical gears to drive two rotors that overlap each other with rotary pistons thereon alternating one another and rotating in the same direction. The elliptical gears also modulate the relative rotational speeds of these rotary pistons to thereby complete compression, power, exhaust and intake strokes four times in one revolution of a power output shaft of the engine. The rotary modulation engine with the above arrangements has smaller volume and improved efficiency as compared to the conventional four-stroke engine that requires two revolutions of the engine's crankshaft to complete four strokes. The rotary modulation engine can be applied to cars, ships, power generators and the like, and has reduced number of parts, volume and manufacturing cost while provides effectively upgraded operation efficiency.