Abstract: In a variable compression ratio internal combustion engine that controls the compression of an internal combustion engine by changing the volume of the combustion chamber of the internal combustion engine in an axial direction of the cylinder, when a target compression ratio (?t) based on an operating condition of the internal combustion engine is at a reference compression ratio (?0) or greater (S102), the compression ratio is changed to the target compression ratio (S103). When the target compression ratio (?t) is lower than the reference compression ratio (?0) (S102), a control is executed to change the compression ratio and also to strength the tumble flow in the combustion chamber (S104).

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: In a spark ignition type internal combustion engine that includes a variable compression ratio mechanism A capable of changing the mechanical compression ratio, and a variable valve mechanism B capable of changing valve characteristics of an intake valve or an exhaust valve, the variable valve mechanism is mechanically coupled to the variable compression ratio mechanism, and the variable valve mechanism is controlled in accordance with the compression ratio-changing operation amount of the variable compression ratio mechanism. The variable valve mechanism is coupled to the variable compression ratio mechanism without intervention of an electronic control unit. Therefore, the possibility of the interference between a piston and an intake valve resulting from an abnormality in a control system that includes an electronic control unit as an intervening unit can be eliminated.

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. The mechanical compression ratio is made maximum so that the expansion ratio becomes 20 or more at the time of engine low load operation, while 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 high load operation.

Abstract: A spark ignition type internal combustion engine comprises a variable compression ratio mechanism able to change a mechanical compression ratio, an actual compression action start timing changing mechanism able to change a start timing of an actual compression action, and an exhaust valve. At the time of engine low load operation, the mechanical compression ratio is maximized to obtain a maximum expansion ratio, and the actual compression ratio is set so that no knocking occurs. The maximum expansion ratio is 20 or more. The closing timing of the exhaust valve at the time of engine low load operation is made substantially intake top dead center. Due to this, even if operating the internal combustion engine in a state of a large expansion ratio, the temperature of the exhaust purification catalyst can be maintained at a relatively high temperature.

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: A variable compression ratio internal combustion engine rotates a camshaft to cause relative movement between a crankcase and a cylinder block. The camshaft has a shaft member, a cam member fixed to the shaft member, and a movable bearing member rotatable with respect to the shaft member. The cam member is rotatably housed in a cam housing hole formed in the crankcase, and the movable bearing member is rotatably housed a bearing housing hole formed in the cylinder block. The length of a line segment joining the centers of the shaft member and the movable bearing member, the center of the movable bearing member being the center of rotation of the movable bearing member with respect to the bearing housing hole, is set to be longer than the length of a line segment joining the centers of the shaft member and the cam member, the center of the cam member being the center of rotation of the cam member with respect to the cam housing hole.

Abstract: An internal combustion engine 1 in which the compression ratio can be varied by moving a cylinder block and a crankcase along the axial direction of the cylinder is mounted on a vehicle body member 29 by at least two portions including a first mount portion 32 provided on a transmission apparatus to and a second mount portion 31 provided on the internal combustion engine 1, wherein said second mount portion 31 is provided on the crankcase 4. The first mount portion 32 and the second mount portion 31 are arranged in such a way that the direction of a rotation moment TD about the output shaft RC1 of the transmission apparatus acting on the internal combustion engine 1 upon combustion becomes opposite to the direction of a rotation moment M1 about the output shaft RC1 generated by a force acting on a cylinder block 3 upon changing the compression ratio.

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: 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: 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: 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.

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 a vehicle body via a 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 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: The invention is directed to a variable compression ratio internal combustion engine in which the compression ratio of the engine can be varied and multiple types of fuels having different combustion velocities are used. The invention provides a technology for achieving excellent engine performance for respective types of fuels. In the variable compression ratio internal combustion engine in which the compression ratio can be varied and multiple types of fuels having different combustion velocities are injected through multiple fuel injection valves, maps from which a target compression ratio of the internal combustion engine is read out are switched in accordance with the fuel used, thereby suppressing knocking or other disadvantages.

Abstract: When controlling the valve characteristics of an intake valve and changing the compression ratio, an upper variation limit compression ratio, which is the upper limit of the variation of compression ratio, is determined according to the actual valve characteristics of the intake valve characteristics control. The upper variation limit compression ratio is set to a valve at which the intake valve does not collide with the piston. When a target compression ratio corresponding to the operation state of the engine is larger than the upper variation limit compression ratio, the compression ratio is set to the upper variation limit compression ratio that is smaller than the target compression ratio. Thus, collision between the intake valve and the piston can be prevented while allowing the compression ratio to be increased up to the maximum compression ratio of the range where the collision does not occur.

Abstract: When controlling the valve characteristics of an intake valve and changing the compression ratio, an upper variation limit compression ratio, which is the upper limit of the variation of compression ratio, is determined according to the actual valve characteristics of the intake valve characteristics control. The upper variation limit compression ratio is set to a valve at which the intake valve does not collide with the piston. When a target compression ratio corresponding to the operation state of the engine is larger than the upper variation limit compression ratio, the compression ratio is set to the upper variation limit compression ratio that is smaller than the target compression ratio. Thus, collision between the intake valve and the piston can be prevented while allowing the compression ratio to be increased up to the maximum compression ratio of the range where the collision does not occur.

Abstract: An internal combustion engine 1 in which the compression ratio can be varied by moving a cylinder block and a crankcase along the axial direction of the cylinder is mounted on a vehicle body member 29 by at least two portions including a first mount portion 32 provided on a transmission apparatus to and a second mount portion 31 provided on the internal combustion engine 1, wherein said second mount portion 31 is provided on the crankcase 4. The first mount portion 32 and the second mount portion 31 are arranged in such a way that the direction of a rotation moment TD about the output shaft RC1 of the transmission apparatus acting on the internal combustion engine 1 upon combustion becomes opposite to the direction of a rotation moment M1 about the output shaft RC1 generated by a force acting on a cylinder block 3 upon changing the compression ratio.

Abstract: In a variable compression ratio mechanism that serves to change the compression ratio of an internal combustion engine by rotating camshafts so as to cause relative movement between a cylinder block and a crankcase, an oil film forming device forms oil films on the sliding portions of camshafts.

Abstract: A variable compression ratio engine has a compression ratio varying mechanism, which moves a cylinder block relative to a lower case. The rotational driving force of a servo motor is transmitted to vertical sliding movements of the cylinder block by means of cam shafts with eccentric cams. First and second rows of spring members and are arranged on both sides of the cylinder block. The resultant spring force of the first and second spring members is applied to the cylinder block and the lower case. The resultant spring force works to reduce the transmission torque of the rotational driving force of the servo motor and assist the compression ratio varying mechanism to vary a compression ratio of the engine. The technique simplifies the control procedure of varying the compression ratio of the engine and reduces the size of the mechanism required.