摘要:
A decompression engine brake device is incorporated with an internal combustion engine. The device comprises an exhaust valve arranged to open and close an exhaust port of a combustion chamber of the engine. A valve stem extends from the exhaust valve. A valve lifter is slidably disposed in a cylinder head of the engine. The valve lifter has the valve stem contacting thereto. An exhaust cam disposed about an exhaust cam shaft is operatively engageable with the valve lifter to actuate the exhaust valve in accordance with a contour of the exhaust cam. An engine brake cam is defined by the exhaust cam. A hydraulically operating device is employed for inducing an operative engagement between the engine brake cam with the valve lifter thereby to actuate the exhaust valve in accordance with a contour of the engine brake cam.
摘要:
A method of producing a valve lifter to be used in a valve operating mechanism of an automotive vehicle. The valve lifter includes a skirt section, a crown section formed one end of the skirt section so that a cam of a camshaft is slidably contactable with the crown section, and a contacting section formed at an inside surface of the crown section and contactable with a valve stem of an engine valve. The production method comprises the following steps in the sequence set forth: (a) cold-forging a base material to form a valve lifter-shaped base material; (b) cold-pressing the base material to shape the valve lifter-shaped base material; (c) grinding an outer surface of the valve lifter-shaped base material to trim an outer shape of the valve-lifter-shaped base material; (d) totally machining the outer surface and an inner surface of the valve-shaped base material to adjust dimensions of parts of the valve lifter-shaped base material; (e) heat-treating only a part of the valve lifter-shaped base material, corresponding to the contacting section, to increase a hardness of the contacting section; and (f) grinding the contacting section to finish the contacting section.
摘要:
A relative angular phase between a timing sprocket 1 and a camshaft 2 is changed by rotating a vane rotor 3 in a normal-rotation direction or in a reverse-rotation direction by way of relative application of hydraulic pressure to one of a timing-advance phase hydraulic pressure chamber 32 and a timing-retard phase hydraulic pressure chamber 33 both defined in a housing 6 and relative release of hydraulic pressure from the other of the hydraulic pressure chambers, in order to vary the opening and closing timing of an intake valve. A restricting mechanism 10 is also provided for reverse rotation of the vane rotor, which may occur during rotating from the timing-retard phase to the timing advance phase owing to a positive fluctuating torque of the camshaft. In the restricting mechanism, a plunger 52 is projected outward by way of a hydraulic pressure supplied to a high-pressure chamber 54, so that the plunger is constantly in abutted-contact with one side wall 13a, and whereby the plunger 52 produces a pushing a force or thrust by virtue of a check valve 56, so as to counteract the positive fluctuating torque. A turning-back phenomenon of the vane rotor can be restricted in presence of torque fluctuations of the camshaft during rotation of the vane rotor, thus enhancing the responsiveness of valve timing control.
摘要:
A valve timing control system for an internal combustion engine is provided. This system includes a sprocket assembly in driven connection with a crankshaft of the engine, a camshaft assembly disposing cams for opening and closing intake- and/or exhaust valves, and a ring gear assembly functioning as a piston slidably disposed between the sprocket assembly and the camshaft assembly for modifying a phase angle relation between the sprocket assembly and the camshaft assembly. The system further includes first and second pressure chambers for exerting fluid pressure on the ring gear assembly to be displaced over a range of first, second, and third positions which correspond to phase angle relations respectively suitable for low, intermediate, and high engine load levels. The ring gear assembly is responsive to fluid pressures in the first and second pressure chambers both below a threshold valve to be arranged at the first position, responsive to elevation in the fluid pressure in the first pressure chamber above the threshold value to be arranged at the second position, and responsive to elevation in the fluid pressures in the first and second pressure chambers both above the threshold value to be arranged at the third position.
摘要:
A variable valve system varies an operation condition of an engine valve by controlling an angular position of a control shaft in accordance with an operation condition of the engine. The system has an actuating mechanism for actuating the control shaft. The actuating mechanism comprises a threaded shaft that is rotated about its axis in accordance with the operation condition of the engine; a nut member operatively engaged with the threaded shaft, so that upon rotation of the threaded shaft the nut member runs axially along the threaded shaft; a link mechanism provided between the control shaft and the nut member, so that the axial movement of the nut member along the threaded shaft induces a rotational motion of the control shaft; and a biasing mechanism that biases the nut member relative to the threaded shaft at least at a predetermined range of the operation condition of the engine valve.
摘要:
A variable valve system varies an operation condition of an engine valve by controlling an angular position of a control shaft in accordance with an operation condition of the engine. The system has an actuating mechanism for actuating the control shaft. The actuating mechanism comprises a threaded shaft that is rotated about its axis in accordance with the operation condition of the engine; a nut member operatively engaged with the threaded shaft, so that upon rotation of the threaded shaft the nut member runs axially along the threaded shaft; a link mechanism provided between the control shaft and the nut member, so that the axial movement of the nut member along the threaded shaft induces a rotational motion of the control shaft; and a biasing mechanism that biases the nut member relative to the threaded shaft at least at a predetermined range of the operation condition of the engine valve.
摘要:
A rocker arm 13 is rocked with respect to a control shaft 32 through a link arm 14 by rotation of a drive shaft 3. With this configuration, a rocking cam 7 is rocked with respect to the drive shaft 3 through a link member 15. A valve lifter 6 is pushed downward by rocking of the rocking cam 7. The control shaft 32 is integrally provided with a control cam which is eccentric with respect to an axis of the control shaft 32. If the control cam is rotated, a rocking fulcrum position of the rocker arm 13 is changed, thereby varying a valve-lift amount. An eccentric bush 22 is provided on an inner peripheral surface of the rocker arm 13 on an outer periphery side of the control cam. The eccentric bush 22 meshes with an inner peripheral gear formed on an inner periphery of the rocker arm 13 by an outer peripheral gear 39b, and is coupled to the rocker arm 13. This coupled state is released by moving the eccentric bush 22 in the axial direction. In this state, the eccentric bush 22 is rotated by a predetermined amount with respect to the control cam and the rocker arm 13, thereby adjusting the valve-lift amount.
摘要:
A first stopper device is arranged between an output element of a planetary gear unit and a drive rotation member driven by an output shaft of an engine. The first stopper device stops a relative rotation therebetween when a relative rotation angle therebetween comes to a first predetermined degree. A second stopper device may be arranged between a free element of the planetary gear unit and an input element of the planetary gear unit. The second stopper device stops a relative rotation therebetween when a relative rotation angle therebetween comes to a second predetermined degree.
摘要:
A VA apparatus includes a rocker arm coaxially swingably supported on a support shaft. The rocker arm is swung by torque transmitted from an engine to operate an engine valve and includes a first arm to which torque is transmitted and a second arm for operating the engine valve. The first and second arms, which are separate and distinct from each other, are swingable relative to each other. Bolts are provided to fix the first and second arms in a predetermined relative angle position.
摘要:
A VA apparatus includes a rocker arm coaxially swingably supported on a support shaft. The rocker arm is swung by torque transmitted from an engine to operate an engine valve and includes a first arm to which torque is transmitted and a second arm for operating the engine valve. The first and second arms are separate and distinct from each other, and are swingable relative to each other. Bolts are provided to fix the first and second arms in a predetermined relative angle position.