Abstract: A spark ignition type internal combustion engine comprises a variable compression ratio mechanism able to change a mechanical compression ratio, a variable valve timing mechanism able to control a closing timing of an intake valve, and an air flow control valve controlling an air flow in a cylinder and able to control the amount of intake air fed into a combustion chamber. The mechanical compression ratio is made maximum so as to obtain the maximum expansion ratio at the time of engine low load operation and the actual compression ratio at the time of engine low load operation is made an actual compression ratio substantially the same as that at the time of engine medium and high load operation. When the engine load is in an extremely low load region, the air flow control valve is used to control an amount of intake air fed into the combustion chamber.

Abstract: An engine provided with a variable timing mechanism (B) able to control a closing timing of an intake valve (7) and a variable compression ratio mechanism (A) able to change a mechanical compression ratio and controlling the closing timing of the intake valve (7) to control the amount of intake air fed into a combustion chamber (5). To obtain an output torque in accordance with the required torque even when the atmospheric pressure changes, when the atmospheric pressure falls, the closing timing of the intake valve (7) is made to approach intake bottom dead center and the mechanical compression ratio is reduced.

Abstract: Disclosed is a spark ignition type internal combustion engine, which comprises a variable compression ratio mechanism capable of changing a mechanical compression ratio, and a variable valve timing mechanism capable of controlling the closing timing of an intake valve. The intake air flow to be fed to the inside of a combustion chamber is controlled mainly by changing the closing timing of an intake valve so that the mechanical compression ratio is set higher at an engine low-load miming time than that at an engine high-load running time. The mechanical compression ratio at the engine low-load running time before completion of the warm-up of the internal combustion engine is set lower than that at the engine low-load running time after completion of the warm-up of the internal combustion engine.

Abstract: In a variable compression ratio internal combustion engine in which the compression ratio is changed by changing the combustion chamber volume, the present invention enables to inhibit irregularities in the air-fuel ratio involved by changing of the combustion chamber volume. In a transition period during which the compression ratio is changed, the actual volume of the combustion chamber realized by a compression ratio changing mechanism is detected. A factor that influences the air-fuel ratio (for example, fuel injection quantity, cylinder intake air quantity or amount of EGR) is controlled based on the actual volume of the combustion chamber thus detected to make the air-fuel ratio substantially equal to that before and after the change of the compression ratio.

Abstract: Provided is a spark ignition type internal combustion engine comprising a variable compression ratio mechanism (A) capable of changing a mechanical compression ratio, and a variable valve timing mechanism (B) capable of controlling the closing timing of an intake valve. At an engine low-load running time, the mechanical compression ratio is made so higher than that at an engine high-load running time that the expansion ratio may be 20 or higher. In case the vacuum in an engine intake passage is lower than the required vacuum, the opening of a throttle valve (17) is reduced, and the valve closing timing of the intake valve is controlled so that the intake air in a quantity according to the engine load may be fed to the inside of a combustion chamber in accordance with the opening of the throttle valve. As a result, a brake booster or the like can be properly activated in the internal combustion engine having its mechanical compression ratio enlarged at the engine low-load running time.

Abstract: A drive device includes a variable compression ratio internal combustion engine that moves a cylinder block relative to crankcase in a cylinder axis direction, and a transmission device. A chain case is made up of a crankcase-side chain case fixed to the crankcase, and a cylinder block-side chain case fixed to the cylinder block. An upper portion of the crankcase-side chain case is supported on a vehicle body via a support member. The transmission device is supported on the vehicle body via the support member. A support member coupling portion that fixes the support member of the crankcase-side chain case includes a rib that improves the rigidity of a front wall portion of the crankcase-side chain case.

Abstract: An internal combustion engine provided with a variable compression ratio mechanism able to change a mechanical compression ratio and an actual compression action start timing changing mechanism able to change a start timing of an actual compression action. An amount of intake air in accordance with the required load is fed into a combustion chamber by controlling the closing timing of the intake valve, while a pressure, temperature or density in the combustion chamber at the end of a compression stroke is maintained substantially constant regardless of the engine load by controlling the mechanical compression ratio.

Abstract: A spark ignition internal combustion engine includes a variable expansion ratio mechanism which can alter the mechanical expansion ratio, and an exhaust variable valve mechanism which can alter the timing for opening an exhaust valve. The mechanical expansion ratio and the timing for opening the exhaust valve are set depending on the engine load such that the mechanical expansion ratio increases and the timing for opening the exhaust valve is retarded to the exhaust bottom dead center side as the engine load decreases. By setting the mechanical expansion ratio in such a manner depending on the engine load, thermal efficiency can be enhanced as compared with a case where the mechanical expansion ratio is set to make the actual compression rate constant for example. Consequently, a spark ignition internal combustion engine exhibiting high thermal efficiency is provided.

Abstract: An internal combustion engine comprises a variable compression ratio mechanism capable of varying the mechanical compression ratio and a variable valve timing mechanism capable of controlling the closing timing of an intake valve. In an engine low-load operation, the mechanical compression ratio is maintained at a maximum mechanical compression ratio. In an engine high-load operation, the mechanical compression ratio is gradually decreased as the engine load increases. In the engine high-load operation, a load at which a predetermined mechanical compression ratio lower than the maximum mechanical compression ratio is obtained is preset, and a throttle valve is closed in the range of loads lower than the preset load.

Abstract: A spark-ignited internal combustion engine includes a variable compression ratio mechanism that changes a mechanical compression ratio and an actual compression ratio start timing-changing mechanism that changes a start timing at which actual compression starts. An actual compression ratio is changed according to the specific heat ratio of an intake gas that is supplied into a cylinder.

Abstract: In an internal combustion engine, a variable compression ratio mechanism able to change a mechanical compression ratio and a variable valve timing mechanism able to control the closing timing of an intake valve are provided. The mechanical compression ratio is made to be the maximum mechanical compression ratio at low load operation regions excluding idling operation, while during idling operation, the mechanical compression ratio is made lower than the maximum mechanical compression ratio.

Abstract: A spark-ignited internal combustion engine includes a variable compression ratio mechanism (A) that changes a mechanical compression ratio and an actual compression ratio 70 start timing-changing mechanism (B) that changes a start timing at which actual compression starts. The maximum mechanical compression ratio while the engine is in operation is reduced with increase in engine speed.

Abstract: An internal combustion engine provided with a variable compression ratio mechanism able to change a mechanical compression ratio and a variable valve timing mechanism able to individually control the opening timing and closing timing of the intake valve. At the time of engine low load operation, the maximum expansion ratio is obtained by making the mechanical compression ratio maximum and, while the mechanical compression ratio is made maximum, the opening timing of the intake valve is maintained at a target opening timing of substantially intake top dead center in the noninterference region where no interference between the valve and the piston occurs.

Abstract: An internal combustion engine 10 comprises a device having a mechanism that moves a cylinder block relative to a crankcase, a worm wheel (wheel) 54 fixed to the mechanism, and a worm 55 meshed with the wheel. The device is disposed at the position in the vicinity of an disposed-face OS1 and within the OS3 disposed-face when the disposed-face is viewed from the front. The internal combustion engine drives the worm for rotatably driving the wheel to drive the mechanism. The internal combustion engine has a noise shielding members 61, 62, and 83 arranged so as to cover a meshing portion EG where the wheel and the worm are meshed with each other, when the disposed-face is viewed from the front. The noise generated at the meshing portion is attenuated by the noise shielding member, and propagated to the outside of the internal combustion engine. Consequently, the noise heard at the outside is reduced.

Abstract: In an internal combustion engine, a variable compression ratio mechanism able to change a mechanical compression ratio and a variable valve timing mechanism able to control the closing timing of an intake valve are provided. At the time of engine low load operation, the mechanical compression ratio is made the maximum so that the expansion ratio becomes 20 or more. Further, at the time of engine low load operation, in part of the operating region or all of the operating region, the actual compression ratio is lowered compared with the time of engine high load operation and, at the time of engine low load operation, at least when the actual compression ratio is being lowered compared with the time of engine high load operation, the throttle valve is made to close.

Abstract: A spark-ignited internal combustion engine includes a variable compression ratio mechanism that changes a mechanical compression ratio, and a variable valve timing mechanism that controls a valve closing timing at which an intake valve is closed, in which the amount of intake air that is supplied into a combustion chamber is controlled by changing the valve closing timing of the intake valve, and when an air-fuel ratio is increased from a first desired air-fuel ratio to a second desired air-fuel ratio, the valve closing timing of the intake valve is brought close to an intake bottom dead center until the air-fuel ratio becomes equal to the second desired air-fuel ratio, without changing a fuel injection amount.

Abstract: An engine provided with a variable timing mechanism (B) able to control a closing timing of an intake valve (7) and a variable compression ratio mechanism (A) able to change a mechanical compression ratio. At the time of engine startup, the closing timing of the intake valve (7) is made the most delayed position so that the least intake air is fed to the inside of the combustion chamber (5) and the mechanical compression ratio is made the maximum compression ratio.

Abstract: An internal combustion engine includes a variable compression ratio mechanism made up of a case-side bearing-forming portion, a block-side bearing-forming portion, and a shaft-shaped drive portion. The case-side bearing-forming portion is formed in an upper portion of a crankcase. The block-side bearing-forming portion extends outward from a lower end portion of an outer wall surface of the cylinder block. The block-side bearing-forming portion is linked to the case-side bearing-forming portion by the shaft-shaped drive portion. Slit-shaped stress reduction groove portions each having an opening in a region between the block-side bearing-forming portion and cylinder bores are formed in a lower surface of the cylinder block. Therefore, even when the block-side bearing-forming portion presses the outer wall surface, the stress reduction groove portions reduce the stress, so that the deformation of the wall surface of each cylinder bore can be restrained.

Abstract: When knocking occurs, a control apparatus for an internal combustion engine increases the rotational speed of a pump to increase the flow rate of a coolant supplied to an area near a combustion chamber wall surface, and controls an actual mechanical compression ratio to a low mechanical compression ratio lower than a mechanical compression ratio set based on the load of the engine. Thus, the pressure of end gas is decreased, and occurrence of knocking is suppressed. Then, the actual mechanical compression ratio is returned to the mechanical compression ratio at a time point at which the temperature of the combustion chamber wall surface has been sufficiently decreased due to the increase in the rotational speed. Thus, occurrence of knocking is suppressed while avoiding the situation where the actual mechanical compression ratio continues to be controlled to the low mechanical compression ratio that is lower than the mechanical compression ratio.

Abstract: The invention provides a technology that enables to control response delay of the supercharger in a variable compression ratio internal combustion engine under acceleration. When the variable compression ratio internal combustion engine is under acceleration, the compression ratio of the internal combustion engine is set to a compression ratio lower than a basic compression ratio that is so determined in accordance with the running condition of the internal combustion engine to realize a predetermined heat efficiency while suppressing knocking, thereby raising the exhaust gas pressure and shortening the response time of the supercharger.