Abstract: The engine with a variable flow rate oil pump includes a subsidiary relief passage that extends from an oil passage-switching valve to a subsidiary oil pump, a main relief passage that extends from the oil passage-switching valve to the main oil pump separately from the subsidiary relief passage, and a check valve that is provided in the subsidiary discharge passage and cuts off the flow of oil from the main discharge passage side to the oil passage-switching valve side. The oil passage-switching valve has a main pressure-adjusting chamber for the main oil pump, a subsidiary pressure-adjusting chamber of for the subsidiary oil pump, and a spool valve that performs partitioning between the main pressure-adjusting chamber and the subsidiary pressure-adjusting chamber.

Abstract: An exhaust system for a variable cylinder engine for assuring purification of exhaust gas without increasing the number of catalysts and an intake system for purifying blow-by gas. The exhaust system includes an activation side exhaust pipe connected to an activation cylinder group that operates normally. A deactivation side exhaust pipe is connected to a deactivation cylinder group wherein fuel supply is stopped under a particular condition. A gathering section is connected to downstream ends of the activation side exhaust pipe and the deactivation side exhaust pipe with a sub-catalyst disposed in the activation side exhaust pipe and a main catalyst disposed at the gathering section. The main catalyst is formed wherein gas passing therethrough is partitioned into flows independent of each other in a flow path direction. The activation side exhaust pipe and the deactivation side exhaust pipe are connected in a mutually independent state to the main catalyst.

Abstract: In an engine having an oil pump wherein an oil filter is incorporated into the oil pump without allowing the oil pump to become large in size. An oil pump and a hydraulic line changeover valve including a spool valve are disposed so as to have axes extending in parallel with each other. The oil pump has a plate-shaped oil filter disposed at a discharge port thereof. The plate-shaped oil filter is curved arcuately along an outer periphery of a pump rotor as viewed from a pump axial direction.

Abstract: An internal combustion engine which includes a valve deactivation mechanism for reducing an output power shock upon changing of the cylinder number. In an internal combustion engine which includes a valve deactivation mechanism driven by a slide pin which is driven by hydraulic pressure, response delay time after a signal is sent to oil control valves until an intake valve and an exhaust valve are activated or deactivated is used to form a control map in response to control parameters, and the valve deactivation mechanism is controlled based on the control map.

Abstract: There is provided an engine for a small vehicle where driven sprockets, around which a cam chain for transmitting power from a crankshaft is wound, are provided at one end of camshafts that form a part of a valve system provided with hydraulic valve-operation mode changing mechanisms; and a valve-moving hydraulic pressure control device, which controls hydraulic pressure applied to the valve-operation mode changing mechanisms, is provided in the engine body. In the engine, it is possible to increase the degree of freedom in disposing the oil passage between the valve-operation mode changing mechanism and the valve-moving hydraulic pressure control device while avoiding the increase in the number of parts and assembly man-hours. A valve-moving hydraulic pressure control device is mounted on the side surface of the engine body on the side opposite to a cam chain in an axial direction of a camshaft.

Abstract: A power system for a vehicle includes a hydraulic pressure generating device, a first hydraulically operated device, a second hydraulically operated device, a common oil channel, a first bifurcated oil channel, a second bifurcated oil channel, and an oil state detector. The first hydraulically operated device is configured to be operated by liquid supplied from the hydraulic pressure generating device. The second hydraulically operated device is configured to be operated by liquid supplied from the hydraulic pressure generating device. The common oil channel is connected to the hydraulic pressure generating device. The first bifurcated oil channel connects the common oil channel and the first hydraulically operated device. The second bifurcated oil channel connects the common oil channel and the second hydraulically operated device. The oil state detector is provided in the common oil channel and configured to detect the state of the liquid.

Abstract: An exhaust system for a variable cylinder engine for assuring purification of exhaust gas without increasing the number of catalysts and an intake system for purifying blow-by gas. The exhaust system includes an activation side exhaust pipe connected to an activation cylinder group that operates normally. A deactivation side exhaust pipe is connected to a deactivation cylinder group wherein fuel supply is stopped under a particular condition. A gathering section is connected to downstream ends of the activation side exhaust pipe and the deactivation side exhaust pipe with a sub-catalyst disposed in the activation side exhaust pipe and a main catalyst disposed at the gathering section. The main catalyst is formed wherein gas passing therethrough is partitioned into flows independent of each other in a flow path direction. The activation side exhaust pipe and the deactivation side exhaust pipe are connected in a mutually independent state to the main catalyst.

Abstract: In an engine having an oil pump wherein an oil filter is incorporated into the oil pump without allowing the oil pump to become large in size. An oil pump and a hydraulic line changeover valve including a spool valve are disposed so as to have axes extending in parallel with each other. The oil pump has a plate-shaped oil filter disposed at a discharge port thereof. The plate-shaped oil filter is curved arcuately along an outer periphery of a pump rotor as viewed from a pump axial direction.

Abstract: The engine with a variable flow rate oil pump includes a subsidiary relief passage that extends from an oil passage-switching valve to a subsidiary oil pump, a main relief passage that extends from the oil passage-switching valve to the main oil pump separately from the subsidiary relief passage, and a check valve that is provided in the subsidiary discharge passage and cuts off the flow of oil from the main discharge passage side to the oil passage-switching valve side. The oil passage-switching valve has a main pressure-adjusting chamber for the main oil pump, a subsidiary pressure-adjusting chamber of for the subsidiary oil pump, and a spool valve that performs partitioning between the main pressure-adjusting chamber and the subsidiary pressure-adjusting chamber.

Abstract: Provided is a power unit for a vehicle including an engine main body of an engine having: a valve system capable of changing operational modes of each engine valve; valve controlling apparatuses for controlling operations of the valve system; and a crankcase housing a transmission, the engine main body being mounted on a vehicle frame. The power unit for a vehicle achieves reduction in size of the engine main body in a direction along the axis of a cylinder, and increases the freedom of arranging parts designed to be placed on an upper end portion of the engine main body. The valve controlling apparatuses are attached to the top surface of the crankcase.

Abstract: A power unit for a small type vehicle wherein a speed change mechanism is disposed on a lateral side of a crankcase on the side of one end of a crankshaft. A valve operation controller for controlling the operations of valve operation mode change mechanisms and a speed change controller for controlling a speed change operation of a speed change mechanism are attached to an engine body, to lay out the valve operation controller and the speed change controller in good balance of center of gravity so as to prevent the center of gravity of the power unit from being deviated to one side. The valve operation controller and the speed change controller being attached to the engine body on the opposite side of the clutch device with respect to a vehicle body center line in a direction along the axis of the crankshaft.

Abstract: There is provided a saddle-riding type small vehicle where a power unit is mounted on a vehicle body frame. The power unit includes a valve control device that controls the operation of valve-operation mode changing mechanisms capable of changing operation modes of engine valves, and a clutch control device that controls the operation of a clutch unit provided between a crankshaft and a shift mechanism so as to shift the connection/disconnection of power transmission. In the vehicle, the valve control device and the clutch control device are disposed to balance the center of gravity, so as to make a power unit compact. A valve control device and a clutch control device are disposed on left and right sides of a center line CB of a vehicle in a width direction of the vehicle.

Abstract: A multicylinder engine for a motorcycle includes a valve actuation mechanism having a hydraulically-operated valve pausing mechanism for holding at least one of an intake valve and an exhaust valve of selected cylinders in a suspended state. The valve actuation mechanism operates the intake valve and the exhaust valve, and controls flow of oil through an oil passage which introduces working oil to the valve pausing mechanism from a hydraulic-pressure control device. Air-bleeding holes are formed in the cylinder head. The air-bleeding holes are fluidly connected with portions of the oil passages that are located at a highest level in the oil passages while the motorcycle is parked in an inclined state with its side stand down.

Abstract: A valve stopping mechanism wherein when hydraulic fluid pressure is low a cylinder operating state is set and a response of a switch from a cylinder stop state to the cylinder operating state is high. An intake valve and an exhaust valve, a first intake valve spring and a first exhaust valve spring are provided for energizing the valves in the direction of closing the valves, valve drive cams, valve stopping mechanisms, on the basis of a stop hydraulic fluid pressure and energization of plunger springs, for selectively generating valve operating and valve stop states. The valve stopping mechanism generates the operating state when the energizing force of the plunger spring is larger than the press force of the stop hydraulic fluid pressure and generates the stop state when the press force of the stop hydraulic fluid pressure is larger than the energizing force of the plunger spring.

Abstract: A V-type engine for a vehicle is provided with front and rear banks including intake and exhaust valves exposed to a combustion chamber, a valve operating device for operating the engine valves, a valve stop mechanism for stopping the operation of the engine valves according to an operational condition of the vehicle, and an actuator for driving a throttle valve. A valve stop mechanism is provided in either the front bank or the rear bank. An actuator provided in one of the front bank and the rear bank excluding the valve stop mechanism is lower in height than the actuator provided in the other of the front bank.

Abstract: A simpler configuration of a mechanism for stopping intake/exhaust valves opened/closed by a valve opening/closing mechanism of a rocker arm. An engine E includes an exhaust valve for opening/closing an exhaust port of an exhaust path with a first exhaust valve spring for energizing the exhaust valve in a valve closing direction. An exhaust valve drive cam is rotated in correspondence with the rotation of an engine crankshaft. A rocker arm is swingably provided between the exhaust valve and the exhaust valve drive cam with one end that abuts on the exhaust valve drive cam being pressed according to rotation of the exhaust valve drive cam and swinging to press the exhaust valve by a press member at the other end to move to the open side. An exhaust valve stopping mechanism is provided between the press member of the rocker arm and the exhaust valve.

Abstract: In a multi-cylinder internal combustion engine, a hydraulic valve rest mechanism is mounted on a valve operating device, which performs open-close driving of an engine valve which is arranged in a cylinder head of an engine body having a plurality of cylinders in an openable-and-closable manner. The hydraulic valve rest mechanism is operated with an oil pressure that is controlled by a hydraulic control device so as to close and rest engine valves of a plurality of cylinders for bringing the cylinders into a rest state Therefore, the miniaturization of the multi-cylinder internal combustion engine along an axis of a crankshaft and can shorten a length of an oil passage which connects a hydraulic valve rest mechanism and a hydraulic control device. A hydraulic control device is arranged on an engine body directly above a portion thereof corresponding to a cylinder that is expected to assume a cylinder rest state.

Abstract: An internal combustion engine which includes a valve deactivation mechanism for reducing an output power shock upon changing of the cylinder number. In an internal combustion engine which includes a valve deactivation mechanism driven by a slide pin which is driven by hydraulic pressure, response delay time after a signal is sent to oil control valves until an intake valve and an exhaust valve are activated or deactivated is used to form a control map in response to control parameters, and the valve deactivation mechanism is controlled based on the control map.

Abstract: An electronic throttle control device in a internal combustion engine for a vehicle can be improved in maintainability and can be reduced in size. An electronic throttle control device in a V-type internal combustion engine for a vehicle has a fuel injection valve and throttle valves in an intake passage. A throttle driving motor controls the opening angle of each throttle valve according to the amount of operation of a throttle grip performed by an operator of the vehicle. The throttle driving motor is located outside a region surrounded by the throttle bodies that are respectively connected to all of intake ports as viewed in plan.

Abstract: A cooling control unit for a water-cooled multi-cylinder internal combustion engine having a cylinder deactivation mechanism for controlling the flow of coolant to prevent the internal combustion engine from being incompletely warmed up when the internal combustion engine returns to its operating condition with all of the cylinders being activated. A communicating passage communicates with a normally activated cylinder coolant jacket as a coolant passage formed for normally activated cylinders and a deactivation-programmed cylinder water jacket as a coolant passage formed for the deactivation-programmed cylinders to communicate with each other, and through which the coolant flows. A bypass passage diverges from the communicating passage and bypasses the deactivation-programmed cylinder coolant jacket. A diversion control valve is provided in a diversion section where the bypass passage diverges from the communication passage.