Abstract: A valve operation control system for an internal combustion engine in which hydraulic pressure applied to a valve operation mode changing mechanism is controlled by hydraulic pressure control means that is formed from a holder mounted on a cylinder head, a spool valve formed by slidably housing a spool valve body in a valve body, and an electromagnetic open/close valve for controlling hydraulic pressure of a pilot hydraulic chamber, wherein the holder (109) is formed by integrally connecting a housed portion (109a) and a projecting portion (109b) by means of a connection portion (109c), the housed portion (109a) being housed between the cylinder head (22R) and a head cover, the projecting portion (109b) projecting outside the cylinder head (22R) and the head cover and having the electromagnetic open/close valve (113, 114) mounted thereon, a seal face (116) with the head cover is formed on the connection portion (109c), and the valve body (110) is provided so as to be connected to the housed portion (109a) whi

Abstract: A valve operation control system for an internal combustion engine in which hydraulic pressure applied to a valve operation mode changing mechanism is controlled by hydraulic pressure control means that is formed from a holder mounted on a cylinder head, a spool valve formed by slidably housing a spool valve body in a valve body, and an electromagnetic open/close valve for controlling hydraulic pressure of a pilot hydraulic chamber, wherein the holder (109) is formed by integrally connecting a housed portion (109a) and a projecting portion (109b) by means of a connection portion (109c), the housed portion (109a) being housed between the cylinder head (22R) and a head cover, the projecting portion (109b) projecting outside the cylinder head (22R) and the head cover and having the electromagnetic open/close valve (113, 114) mounted thereon, a seal face (116) with the head cover is formed on the connection portion (109c), and the valve body (110) is provided so as to be connected to the housed portion (109a) whi

Abstract: An inner-space-sectioned tube wherein, in manufacturing the tube having four or more independent fluid channels formed inside thereof, while at least two lengths of inner tubes are set to inscribe an outer tube, cold working is applied, which is a simple manufacturing process, thereby enabling to reduce the number of cold drawing passes and allowing the inner space of the tube, even if the outer tube is small in size, to effectively be allocated for four independent fluid channels. Further, this inner-space-sectioned tube adopts a simple tube structure wherein the number of constituting members is reduced, thereby enabling to reduce weight while ensuring tube strength and to achieve further reduction of manufacturing costs.

Abstract: An inner-space-sectioned tube wherein, in manufacturing the tube having four or more independent fluid channels formed inside thereof, while at least two lengths of inner tubes are set to inscribe an outer tube, cold working is applied, which is a simple manufacturing process, thereby enabling to reduce the number of cold drawing passes and allowing the inner space of the tube, even if the outer tube is small in size, to effectively be allocated for four independent fluid channels. Further, this inner-space-sectioned tube adopts a simple tube structure wherein the number of constituting members is reduced, thereby enabling to reduce weight while ensuring tube strength and to achieve further reduction of manufacturing costs.

Abstract: In a valve operating system for a multi-cylinder internal combustion engine, which is capable of closing and stopping operation of both of a pair of intake valves in a cylinder to provide a stopped state of a cylinder, intake valves are independently operatively connected to first and second driving rocker arms which abut against a pair of stopping portions provided in a completely circular shape without a cam lobe on a cam shaft. A first free rocker arm is provided and abuts against a substantially stopping cam, and a second free rocker arm is provided and abuts against an operating cam. A first connection switch-over device is provided in the first driving rocker arm and the first free rocker arm, and a second connection switch-over device is provided in the second driving rocker arm and the second free rocker arm. A third connection switch-over device is provided in the first driving rocker arm, the second driving rocker arm and the second free rocker arm.

Abstract: A valve operating apparatus for driving intake valves and exhaust valves of an internal combustion engine has a valve operating cam and a rocker arm unit. The rocker arm unit is made up of driving rocker arms which operatively contact the valves, a free rocker arm which is free from contact with the valves, and a changeover mechanism for varying the valve lift amount and timing of opening and closing the valves by connecting the rocker arms and releasing the connection between them. The free rocker arm is urged by a torsion spring so as to operatively contact the valve operating cam. The torsion spring is disposed inside a hollow rocker arm shaft of the rocker arm unit. In case the free rocker arm is fixed to the rocker arm shaft, a coil spring is disposed inside a supporting portion for rotatably supporting the rocker arm shaft such that the free rocker arm is urged by the coil spring via the rocker arm shaft.

Abstract: A valve operating system in a multi-cylinder internal combustion engine, including an intake valve and an exhaust valve valve operating/stopping switch-over device capable of switching over the operation and non-operation or stoppage of an intake valve and an exhaust valve, respectively. Each valve operating/stopping switch-over device includes a hydraulic pressure chamber for exhibiting a hydraulic pressure force in one axial direction and a return spring for exhibiting a spring force in the other axial direction for opposing the hydraulic pressure force, so that the operation and stoppage of the intake and exhaust valves is switched over from one to another by controlling the hydraulic pressure applied to the hydraulic pressure chambers. A single hydraulic pressure control valve is connected commonly to the hydraulic pressure chambers in the intake valve and exhaust valve operating/stopping switch-over device.

Abstract: In an internal combustion engine comprising a valve operating device which is disposed in a cylinder head coupled to an upper surface of a cylinder block and which includes a valve operating cam shaft connected to a crank shaft rotatably carried in a lower engine body portion including the cylinder block, and valve operation characteristic changing means for changing, in accordance with a variation in hydraulic pressure in a hydraulic pressure chamber, the operation characteristics of an engine valve which is supported in the cylinder head for opening and closing, a lower oil supply system and an upper oil supply system are disposed independently of each other.

Abstract: A valve operating mechanism for an internal combustion engine has a low-speed cam for operating the intake or exhaust valves during low-speed operation of the engine and a high-speed cam for operating the intake or exhaust valves during high-speed operation of the engine. A low-speed lubricating oil passage is provided for supplying lubricating oil to the low-speed cam and a separate high-speed lubricating oil passage is provided for supplying lubricating oil to the high-speed cam. A control valve is connected to said low-speed and high-speed lubricating oil passages for selectively supplying maximum oil pressure to the high-speed lubricating oil passage during high-speed operation while restricting the rate of flow of oil during low-speed operation of the engine and supplying maximum oil pressure to the low-speed lubricating oil passage during low-speed operation of the engine while restricting or eliminating the oil supplied thereto during high-speed operation.