Variable valve timing system for induction control of an internal combustion engine
AssigneeNissan Motor Co., Ltd.
InventorShunichi Aoyama
Life of this patent
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Abstract
The present invention relates to a variable valve timing system for an internal combustion engine which cyclically opens and closes a port providing fluid communication between a combustion chamber and a conduit leading thereto and which delays the closure of the port in response to a signal indicative of the power output required of the engine in order to vary the ratio of the mass of fluid inducted into the chamber to the mass of fluid expelled from said chamber during the period the port is open so that the mass of fluid retained in the chamber after closure of the port can be controlled without the use of a throttle valve.
Claims16
An apparatus for actuating an inlet valve associated with a combustion chamber of an internal combustion engine having an exhaust valve, the combustion chamber undergoing a volume expansion during a first phase of the engine operation and a volume contraction during a subsequent second phase of the engine operation,
- the valve actuating apparatus comprising:
- a leading cam;
- a trailing cam;
- a hydraulic actuator having a hydraulic chamber, said hydraulic actuator including a first cam follower cooperating with said leading cam, a second cam follower cooperating with said trailing cam, said first and second cam followers including first and second pistons, respectively,
- said hydraulic actuator including a third valve tappet engaging the inlet valve, said third valve tappet including a third piston,
- said first, second and third pistons being reciprocally movable and defining said hydraulic chamber within said actuator, said hydraulic chamber being pressurized by reciprocation of said first and second pistons induced by rotation of said first and second cams;
- a controller to vary a phase difference between said first and second cams.
An internal combustion engine having a crankshaft comprising:
- a combustion chamber;
- a conduit fluidly communicating with said combustion chamber through a port;
- an inlet valve for said port;
- a variable valve timing system which opens said inlet valve during one phase of the engine operation and variably delays the closure of said inlet valve so as to overlap a portion of the subsequent phase of the engine operation, said variable valve timing system responding to an increase in a demand signal representing demand on the engine to reduce the degree of overlap;
- said variable valve timing system comprising:
- a first cam fixedly mounted on a first cam shaft;
- a second cam fixedly mounted on a second cam shaft;
- a cylinder;
- a first piston reciprocatively received in said cylinder, said first piston having a tappet portion which follows said first cam;
- a second piston reciprocatively received in said cylinder, said second piston having a tappet portion which follows said second cam;
- said first and second cam shafts being arranged to rotate in synchronism with the crankshaft of the engine and with a predetermined phase difference between said first and second cams;
- a third piston reciprocatively received in said cylinder, said third piston having a tappet portion engaging said inlet valve,
- said first, second and third pistons defining a variable volume space within said cylinder which is filed with a hydraulic fluid, the hydraulic fluid being cyclically pressurized by the reciprocation of said first and second pistons induced by the rotation of said first and second cams, respectively, to cyclically reciprocate said third piston which in turn opens and closds said inlet valve;
- means for reducing the phase difference between said first and second cams in response to the magnitude of said demand signal increasing toward a maximum value thereof.
A variable valve timing system for an internal combustion engine having a crankshaft, comprising:
- first and second cams fixedly mounted on first and second cam shafts respectively, said first and second camshafts being arranged to rotate in synchronism with the crankshaft of said engine and with a predetermined phase difference between said cams;
- a cylinder which reciprocatively receives therein first, second and third pistons, which pistons therebetween define a closed variable-volume chamber within said cylinder, which chamber is filled with a working fluid,
- said first and second pistons respectively engaging said first and second cams to be reciprocatively driven thereby to cyclically pressurize said working fluid to in turn reciprocatively drive said third piston;
- and
- means for reducing the phase difference between said first and second cams in response to the magnitude of a control signal increasing toward a maximum valve thereof.
Dependencies are inferred from the claim text.