Abstract: A control device for a diesel engine has a valve timing switching mechanism capable of selectively switching between first opening/closing timing and second opening/closing timing for an exhaust valve. The first opening/closing timing is set such that the period for which the exhaust valve is open overlaps the period for which an intake valve is open, and that opening start timing for the exhaust valve is after bottom dead center of expansion stroke of a piston. The second opening/closing timing is set such that opening start timing for the exhaust valve is advanced compared with the opening start timing according to the first opening/closing timing. A control unit controls the valve timing switching mechanism so that the exhaust valve is opened and closed according to the first opening/closing timing, at least when the diesel engine is operating in a predetermined cold condition.

Abstract: A variable valve apparatus comprises a rocker shaft having an eccentric shaft rendered eccentric, a cam provided below the rocker shaft and rotationally driven, a support shaft disposed at a height equal to the rocker shaft, a first arm rockingly supported by the rocker shaft and capable of driving a valve, a second arm rockingly supported by the eccentric shaft and driven by the cam, and a third arm rockingly supported by the support shaft and displaced by rocking of the second arm for driving the first arm, and turns the rocker shaft in the direction of R2 to continuously change the valve opening timing and lift amount of the valve.

Abstract: A variable valve apparatus comprises a rocker shaft having an eccentric shaft rendered eccentric, a cam provided below the rocker shaft and rotationally driven, a support shaft disposed at a height equal to the rocker shaft, a first arm rockingly supported by the rocker shaft and capable of driving a valve, a second arm rockingly supported by the eccentric shaft and driven by the cam, and a third arm rockingly supported by the support shaft and displaced by rocking of the second arm for driving the first arm, and turns the rocker shaft in the direction of R2 to continuously change the valve opening timing and lift amount of the valve.

Abstract: A variable valve mechanism has a switching mechanism for transmitting cam displacement to a first rocker arm from a second rocker arm. A camshaft is disposed obliquely above a rocker shaft. A first abutting portion and a second abutting portion are disposed in a dead space between an upper side of the rocker shaft and a side of the camshaft. The first abutting portion rotationally displaces in a rotational direction of rocker arms together with the first rocker arm. The second abutting portion rotationally displaces together with the second locker arm. The second abutting portion abuts on the first abutting portion from a rotating direction of rocker arms. In the switching mechanism thus configured, displacement of the second rocker arm is transmitted to the first rocker arm with reduced stress burden.

Abstract: The valve drive apparatus of the invention comprises an exhaust valve drive mechanism capable of changing an open/close timing of an exhaust valve, and a control device which controls the exhaust valve drive apparatus so as to release the exhaust valve during an intake stroke, independently of an exhaust stroke, in an EGR mode. Preferably, the exhaust valve drive mechanism comprises a first exhaust cam which defines the exhaust valve releasing timing and the amount of valve lift in the exhaust stroke, and a second exhaust cam which defines the exhaust valve releasing timing and the amount of valve lift during the intake stroke. In an normal mode, the displacement of the first exhaust cam is transmitted to the exhaust valve, and in the EGR mode, the displacement of the second exhaust cam is transmitted to the exhaust valve, in addition to the displacement of the first exhaust cam.

Abstract: A variable valve mechanism has a switching mechanism for transmitting cam displacement to a first rocker arm from a second rocker arm. A camshaft is disposed obliquely above a rocker shaft. A first abutting portion and a second abutting portion are disposed in a dead space between an upper side of the rocker shaft and a side of the camshaft. The first abutting portion rotationally displaces in a rotational direction of rocker arms together with the first rocker arm. The second abutting portion rotationally displaces together with the second locker arm. The second abutting portion abuts on the first abutting portion from a rotating direction of rocker arms. In the switching mechanism thus configured, displacement of the second rocker arm is transmitted to the first rocker arm with reduced stress burden.

Abstract: The valve drive apparatus of the invention comprises an exhaust valve drive mechanism capable of changing an open/close timing of an exhaust valve, and a control device which controls the exhaust valve drive apparatus so as to release the exhaust valve during an intake stroke, independently of an exhaust stroke, in an EGR mode. Preferably, the exhaust valve drive mechanism comprises a first exhaust cam which defines the exhaust valve releasing timing and the amount of valve lift in the exhaust stroke, and a second exhaust cam which defines the exhaust valve releasing timing and the amount of valve lift during the intake stroke. In an normal mode, the displacement of the first exhaust cam is transmitted to the exhaust valve, and in the EGR mode, the displacement of the second exhaust cam is transmitted to the exhaust valve, in addition to the displacement of the first exhaust cam.

Abstract: A multiple step valve opening control system, particularly for an EGR control valve unit, having a plurality of valve lifts. The system comprises a valve member for opening a fluid passage in multiple steps, a first piston slidably housed in a housing, a second cylinder substantially coaxial with the first piston, a second piston fitted in the second cylinder and coupled to the valve member, and a first piston stroke regulating member which is moved selectively to a first position for regulating an allowable displacement of the first piston to a first predetermined extent (l.sub.1) or to a second position for regulating the allowable displacement of the first piston to the first predetermined first extent (l.sub.1) plus a third predetermined extent (l.sub.3). By changing the position of the first piston displacement regulating member, the valve member is opened by various valve lifts.