Abstract: A variable compression ratio internal combustion engine is equipped with a variable compression ratio mechanism that changes an engine compression ratio depending on the rotational position of a first control shaft arranged in an oil pan, and an actuator that changes and holds the rotational position of the first control shaft, and a linking mechanism configured to link the actuator and the first control shaft. The linking mechanism has a lever linked to the first control shaft, and a connecting pin configured to rotatably link the tip of an arm part extending radially outward from the center of the first control shaft and one end of the lever. At least when having been set to the highest compression ratio, the first connecting pin is configured to be submerged below an oil level of the oil pan.

Abstract: It has variable compression ratio mechanism (10) that changes engine compression ratio depending on the rotational position of first control shaft (14). First control shaft (14) and second control shaft, which is connected to a motor, are coupled together by lever (24) of coupling mechanism (20). First arm portion (25) of first control shaft (14) and one end of lever (24) are rotatably coupled together by first coupling pin (26). When viewed in the axial direction of this first coupling pin (26), at least at a given compression ratio position, first coupling pin (26) is arranged at a position away from bearing cap (30) that is for rotatably supporting first control shaft (14).

Abstract: An internal combustion engine (1) that has a variable-compression-ratio mechanism (2) has variable valve mechanisms (7, 8) for an intake valve (4) and an exhaust valve (5), respectively. If a malfunction in the variable-compression-ratio mechanism (2), which controls a mechanical compression ratio via an electric motor (31), is detected from the amplitude of variations in an actual compression ratio, then if the fuel supply to the engine is cut, a throttle valve (14) is opened wider than would be the case if the variable-compression-ratio mechanism (2) were not malfunctioning, thereby reducing in-cylinder negative pressure during the intake stroke. Also, the timing with which the intake valve is closed is advanced and the timing with which the exhaust valve is opened is retarded, increasing the in-cylinder positive pressure during the compression and power strokes. This prevents the variable-compression-ratio mechanism (2) from increasing the compression ratio when control is lost.

Abstract: A wave motion gearing speed reducer (20) is disposed between a driving motor (15) and a control shaft (11) of a variable compression ratio mechanism. There are provided a input shaft rotation sensing sensor (31) to sense the rotational position of an input shaft (16) of the speed reducer (20), and an output shaft rotation sensing sensor (32) to sense the rotational position of an output shaft (12) of the speed reducer (20). When a discrepancy quantity (??) between sensed quantities of both sensors is greater than or equal to a predetermined value, a judgment is made that a ratcheting of slippage of an engaging position between internal teeth (22) and external teeth (25) is generated.

Abstract: There are provided a variable compression-ratio mechanism (20) capable of varying an engine compression ratio in accordance with a rotational position of a control shaft (24); a speed reducer (44) configured to reduce in speed a rotational power of an actuator and transmit the speed-reduced rotational power to the control shaft (24); and a speed-reducer accommodating case (43) accommodating the speed reducer (44). An input shaft of the speed reducer (44) which is connected to the actuator has a shaft center line extending along a horizontal direction, and at least a part of the input shaft is kept under a lubricating oil retained in the speed-reducer accommodating case (43). The input shaft of the speed reducer (44) is swung by a predetermined swing angle to avoid inadequate lubrication of the input shaft of the speed reducer (44), during an operating state where the engine compression ratio is maintained constant.

Abstract: An actuator mounting structure of a variable compression ratio internal combustion engine includes: a variable compression ratio mechanism arranged to vary an engine compression ratio in accordance with a rotational position of a control shaft; an actuator arranged to drivingly rotate the control shaft, the actuator being fixed on an actuator mounting portion provided to a side wall of a main body of the engine by using a plurality of fixing bolts, and a rigidity improvement section arranged to improve a mounting rigidity of the actuator to the actuator mounting portion, and which is provided within an inter-bolt distance between two bolts of the plurality of the fixing bolts, which are located on the both sides in a direction of a crank shaft.

Abstract: A control system is provided with a piston TDC (top dead center) position variable mechanism and a valve operational characteristics variable mechanism. An actual distance between the valve and the piston of closest approach is calculated based on the actual operation states of these mechanisms. In addition, a limit distance of closest approach necessary to avoid interference between the valve and the piston is set, and, the piston TDC position variable mechanism and the valve operational characteristics variable mechanism are controlled to be driven to increase the actual distance.

Abstract: A control device for a variable compression ratio internal combustion engine is equipped with a variable compression ratio device capable of changing an engine compression ratio of the internal combustion engine. The control device detects or estimates the temperature of an exhaust component (B11), and sets a target exhaust gas temperature based on the temperature of the exhaust component (B12). A mixing ratio and compression ratio set section (B13) sets a fuel mixing ratio and the engine compression ratio within such a range as not to exceed the target exhaust gas temperature such that energy loss becomes minimum.

Abstract: A variable compression ratio internal combustion engine includes a variable compression ratio mechanism, an actuator and a linking mechanism. The actuator is varies and maintains a rotational position of the first control shaft. The linking mechanism includes a second control shaft and a lever. The second control shaft is selectively turned by the actuator. The lever links the second control shaft to the first control shaft such that transference of vibration of the first control shaft to the second control shaft is suppressed. The first control shaft is pivotally linked to a first end of the lever by a first linking pin. The second control shaft is pivotally linked to a second end of the lever by a second linking pin.

Abstract: It is an object to increase the reliability and durability by minimizing mixing/entry of foreign matter (contaminants) into a speed reducer. The speed reducer is provided for reducing rotation of an actuator of a variable compression ratio mechanism and for transmitting the reduced rotation to a control shaft of the variable compression ratio mechanism. The actuator and the speed reducer are attached to a sidewall of an engine main body with a housing therebetween. An oil filter, which removes contaminants from within lubricating oil, is attached to the housing with an oil-passage-forming body therebetween. A portion of the lubricating oil supplied from the oil filter immediately after having been filter-purified is supplied via a bypass oil passage, formed in the oil-passage-forming body and the housing, into a speed-reducer accommodation chamber of the housing.

Abstract: In a variable compression ratio engine with a connecting mechanism including a first control shaft to control the compression ratio of a variable compression ratio, a second control shaft to be rotated/retained by an actuator, and a lever interconnecting the first control shaft and the second control shaft, a speed reduction ratio from the actuator to the first control shaft through the rotation power transmission path is set to be maximum at the maximum compression ratio, at a preset compression ratio (i.e. at any given compression ratio between the minimum compression ratio and the maximum compression ratio) the speed reduction ratio is set to be minimum, and the reduction ratio is set higher at the maximum compression ratio as compared to the intermediate compression ratio.

Abstract: A variable compression ratio internal combustion engine basically has a main engine body and a variable compression ratio mechanism. A housing is attached to an outside wall of the main engine body to support an actuator. The variable compression ratio mechanism varies an engine compression ratio according to a rotational position of a first control shaft by the actuator. A second control shaft links the actuator to the first control shaft. A bearing includes a pair of split bearing bodies that rotatably holds and supports the second control shaft on the housing. The split bearing body that is farther from the main engine body has higher in rigidity than the housing. The bearing is fixed to the side wall of the main engine body by fixing bolts that pass through both of the split bearing bodies and thread into the side wall of the main engine body.

Abstract: A control system is provided with a piston TDC (top dead center) position variable mechanism and a valve operational characteristics variable mechanism. An actual distance between the valve and the piston of closest approach is calculated based on the actual operation states of these mechanisms. In addition, a limit distance of closest approach necessary to avoid interference between the valve and the piston is set, and, the piston TDC position variable mechanism and the valve operational characteristics variable mechanism are controlled to be driven to increase the actual distance.

Abstract: In a variable compression ratio engine with a connecting mechanism including a first control shaft to control the compression ratio of a variable compression ratio, a second control shaft to be rotated/retained by an actuator, and a lever interconnecting the first control shaft and the second control shaft, a speed reduction ratio from the actuator to the first control shaft through the rotation power transmission path is set to be maximum at the maximum compression ratio, at a preset compression ratio (i.e. at any given compression ratio between the minimum compression ratio and the maximum compression ratio) the speed reduction ratio is set to be minimum, and the reduction ratio is set higher at the maximum compression ratio as compared to the intermediate compression ratio.

Abstract: A variable compression ratio internal combustion engine basically has a main engine body and a variable compression ratio mechanism. A housing is attached to an outside wall of the main engine body to support an actuator. The variable compression ratio mechanism varies an engine compression ratio according to a rotational position of a first control shaft by the actuator. A second control shaft links the actuator to the first control shaft. A bearing includes a pair of split bearing bodies that rotatably holds and supports the second control shaft on the housing. The split bearing body that is farther from the main engine body has higher in rigidity than the housing. The bearing is fixed to the side wall of the main engine body by fixing bolts that pass through both of the split bearing bodies and thread into the side wall of the main engine body.

Abstract: A variable compression ratio internal combustion engine includes a variable compression ratio mechanism, an actuator and a linking mechanism. The actuator is varies and maintains a rotational position of the first control shaft. The linking mechanism includes a second control shaft and a lever. The second control shaft is selectively turned by the actuator. The lever links the second control shaft to the first control shaft such that transference of vibration of the first control shaft to the second control shaft is suppressed. The first control shaft is pivotally linked to a first end of the lever by a first linking pin. The second control shaft is pivotally linked to a second end of the lever by a second linking pin.

Abstract: A variable compression ratio device for an internal combustion engine comprises a control shaft (7) that varies a compression ratio of the internal combustion engine in accordance with a rotational displacement, and a linear actuator (13, 16, 17, 18). A connecting link (12) connects a first point (14) offset from a rotation axis (7a) of the control shaft (7) to an actuator rod (13) of the linear actuator (13, 16, 17, 18). Thus, a bending load acting on the actuator rod (13) is reduced, and controllability of the compression ratio is improved.

Abstract: A multi-link variable compression ratio engine is provided with a crankshaft, a piston, a control shaft, a linkage, a motor and a reduction mechanism. The crankshaft moves the piston within an engine cylinder. The control shaft has an eccentric axle eccentric relative to its center-axis. The linkage operatively connects the piston to the crankshaft and the crankshaft to the eccentric axle of the control shaft. The motor rotates the control shaft so a top-dead-center position of the piston changes to vary compression ratios by changing the positions of the eccentric axle and the linkage. The reduction mechanism couples the motor to the control shaft to transmit a reduced rotation of the motor to the control shaft so a reduction ratio of a rotation angle of the motor to a rotation angle of the control shaft is less at high-compression ratios than at intermediate compression ratios.

Abstract: A variable compression ratio engine. The engine includes a piston disposed in a cylinder bore and constituting a combustion chamber, a variable compression ratio mechanism connected to the piston and causing a top dead center position of the piston to vary, an actuator connected to the variable compression ratio mechanism to actuate the variable compression ratio mechanism, and a controller connected to the actuator to control an engine state and the actuator. The controller performs operations including setting the compression ratio corresponding to a state of the engine, actuating the actuator so that the compression ratio is set, determining whether a state of the engine is either a state allowing actuation of the actuator, or a state limiting actuation of the actuator, and limiting actuation of the actuator in the state limiting actuation of the actuator.

Abstract: An engine intake control apparatus for an engine that comprises at least one combustion chamber operatively connected to an intake port and an intake valve associated with each intake port, wherein the intake valve is adapted to open and close the intake port is disclosed herein. The intake control apparatus comprises a variable valve operating mechanism and a controller. The variable valve operating mechanism is configured and arranged to selectively change a valve closing timing and a valve lift amount of the intake valve. The controller is configured and arranged to control the variable valve operating mechanism when the engine is in a low load condition. The valve closing timing is determined such that an actual compression ratio of the engine is reduced relative to the actual compression ratio when the engine is operating in a high load condition. The valve lift amount is smaller when the engine is in the low load condition relative to the valve lift amount when the engine is in the high load condition.