Compression ratio

About: Compression ratio is a research topic. Over the lifetime, 12998 publications have been published within this topic receiving 135829 citations.

Method and device for controlling internal combustion engine with compression ratio variable mechanism

Abstract: PROBLEM TO BE SOLVED: To solve a problem in a conventional engine such that unless the control of a compression ratio is performed when a battery is not normal, such an effect as an increase in combustion efficiency by the control of the compression ratio can not be enjoyed in the engine with the compression variable mechanism. SOLUTION: The state of the battery 60 is measured under high load conditions such that a starter motor 45 is used. When the battery 60 is normal (F = 1), the compression ratio is controlled with a normal map (step S150). When the battery is determined to be not normal, the map is switched to a map less causing the switching of the compression ratio than the normal map and the compression ratio switching control is performed (step S160). Thereby, even when the battery 60 is not normal, the switching control of the compression ratio can be performed. Accordingly, such a merit that the combustion efficiency of the engine 20 can be improved by the control of the compression ratio can be enjoyed by preventing a useless load from applying on the battery 60. COPYRIGHT: (C)2005,JPO&NCIPI

Effects of Compression Ratio and CO_2 on the Process of HCCI Combustion Fueled with DME

Abstract: A 2-135 C.I. engine was modified to a dimethyl ether (DME) homogenous charge compression ignition (HCCI) combustion. The experimental results show that DME HCCI combustion presents almost zero NO_x emission and smokeless behavior. Within the engine load range, the emission of CO decreases with the increase of engine load, while the HC emission does not change much. The HCCI combustion of DME presents remarkable two-stage combustion characteristics. The first combustion stage starts at around 28° CA. The way of increase fuel input to increase engine load range is very likely to lead to knock. In order to control the ignition and combustion phase of HCCI, the effects of change of compression ratio and diluent gas CO_2 added to the engine intake flow on the combustion were evaluated. The experimental results show that both methods are quite effective in enlarging engine load range.

Universal performance of internal combustion engines with variable specific heats of working fluid

Abstract: The performance of a generalized irreversible internal combustion engine cycle model consisting of two heating branches, two cooling branches and two adiabatic branches with heat transfer, friction and variable specific heats of working fluid was analyzed by using finite-time thermodynamics. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between the power output and the efficiency of the cycle are derived by numerical example. Moreover, the effects of variable specific heats of working fluid and cycle process on cycle performance are analyzed. The performances of the cycle with variable and constant specific heats of working fluid are compared. The results obtained herein include the performance characteristics of irreversible reciprocating Diesel, Otto, Atkinson, Brayton, Dual and Miller cycles.

Wankel engine with variable compression ratio

Abstract: The invention discloses a wankel engine with a variable compression ratio. The wankel engine is at least composed of a cycloid-shaped cylinder body, a triangular rotor, a variable-volume groove and a reset spring. The variable-volume groove at least comprises a groove body, groove cavities, a sliding block and minimum-volume baffles. When the engine works, a suction stroke and a compression stroke are conducted in sequence. When the rotor rotates to the position of a smallest work cavity, an oil and gas mixture is ignited, fuel gas expands to act, and the triangular rotor is pushed to rotate. After an acting stroke is completed, an exhaust door is opened, an exhaust stroke is conducted, and then a second suction stroke, a second compression stroke, a second acting stroke and a second exhaust stroke are conducted, and circulation is conducted in such a manner. In the acting stroke, the fuel gas pushes the rotor to rotate at a high speed, generated centrifugal force enables the sliding block in the groove to generate the movement in the direction opposite to the movement direction of the rotor, and therefore the volume of the defined groove is changed. Due to the fact that the displacement generated by the sliding blocks is different and the volumes of the groove are different under different rotating speeds, the engine has a high compression ratio at a low rotating speed and has a low compression ratio at a high rotating speed.

High compression ration internal-combustion engine.

Abstract: This invention relates to a high compression ratio internal-combustion engine. The engine installs the control valve (4) which opens and shuts the connection hole (31) between pre-chamber (3) which pre-burn fuel and main chamber. and controls the fuel injection and the opening and shutting of the control valve (4) according to the rotation of the crank shaft. The air layer (32) is installed on the outer part of pre-chamber (3) and the engine is assumed to be of heat insulation structure. The connection hole (31) is opened at the last period of compression step near upper dead point, compressed and hot air is putin to the pre-chamber. The activated fuel is mixed with the air and is burning by the hot air, but the fuel in the pre-chamber is so rich that the generation of NOX is controlled. Afterwards, the non-burned fuel and flame generated in pre-chamber is ejected into main chamber, and fuel and hot air in the main chamber are reacted, then combuston ends. Even if the high compression ratio is maintained, the engine of this invention does a smooth engine operation.