Valve timing control system for internal combustion engine

Details Valve timing control system for internal combustion engine Valve timing control system for internal combustion engine

2000-11-28

2001-12-04

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090170

Reexamination Certificate

active

06325029

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing control system for controlling valve operation timing(s) for an intake valve and/or an exhaust valve of an internal combustion engine.
2. Description of Related Art
As the conventional valve timing control system for the internal combustion engine known heretofore, there may be mentioned a control system such as disclosed, for example, in Japanese Patent Publication No. 317504/1997. In this known valve timing control system, such an arrangement is adopted in which one of the intake valve and the exhaust valve which exhibits such valve characteristic which allows the characteristic value of the internal combustion engine to attain speedily a desired or target characteristic value is selected, whereon control is performed such that the amount of a hydraulic fluid supplied to one of actuating mechanisms which is destined for changing the characteristic of the valve selected is increased more than the amount of the hydraulic fluid supplied to the other actuating mechanism.
For better understanding of the concept underlying the present invention, description will first be made in some detail of the conventional valve timing control system for the internal combustion engine known heretofore.
FIG. 18
of the accompanying drawings is a block diagram showing schematically and generally a configuration of a conventional valve characteristic (or performance) control system. As can be seen in the figure, this known valve timing control system is comprised of an intake valve M
4
for opening/closing an intake pipe M
3
for the intake air which pipe leads to a combustion chamber M
2
defined within a cylinder of an internal combustion engine M
1
, an exhaust valve M
7
for opening/closing an exhaust pipe M
6
provided for discharging an exhaust gas resulting from the combustion of the air-fuel mixture within the combustion chamber M
2
within the engine cylinder, first and second actuating mechanisms M
5
and M
8
adapted to be actuated under hydraulic pressure for changing valve characteristics of the intake valve M
4
and the exhaust valve M
7
, respectively, a hydraulic fluid supply source M
10
for supplying a hydraulic fluid such as oil to both the actuating mechanisms M
5
and M
8
by way of fluid passages M
9
, respectively, a hydraulic fluid flow regulating means M
11
for regulating or adjusting the amount or rate of the hydraulic fluid supplied from the hydraulic fluid supply source M
10
to both the actuating mechanisms M
5
and M
8
, respectively, an engine operating state detecting means M
12
for detecting the operating states of the internal combustion engine M
1
, a control means M
13
for changing the characteristics or performances of both the intake and exhaust valves, respectively, through regulation by the hydraulic fluid flow regulating means M
11
on the basis of the detected engine operation state so that the characteristic value of the internal combustion engine M
1
can assume the desired or target characteristic value, wherein the control means M
13
is so designed as to select on the basis of the prevailing engine operating state one of the intake valve M
4
and the exhaust valve M
7
which exhibits such valve characteristic which causes the characteristic value of the internal combustion engine M
1
to reach more speedily the target characteristic value, while controlling simultaneously the hydraulic fluid flow regulating means M
11
so that the amount of hydraulic fluid supplied to one of the actuating mechanisms (M
5
or M
8
) which is destined for changing the valve characteristic of the selected valve is increased more than the amount of the hydraulic fluid supplied to the other actuating mechanism (M
8
or M
5
).
At this juncture, it should be mentioned that the term “valve characteristic” used herein means at least one of a valve-open timing or a valve-close timing of the intake valve and the exhaust valve. Further, with the phrase “characteristic value of the internal combustion engine”, it is contemplated to mean a quantity which changes in response to the changes of the intake valve and the exhaust valve such as, for example, output characteristic, exhaust characteristic, fuel consumption ratio, stability in the idling operation of the engine or the like.
As will be appreciated from the foregoing, in the conventional valve timing control system of the structure described above, such arrangement is adopted in which one of the intake valve and the exhaust valve which exhibits the valve characteristic which allows the characteristic value of the internal combustion engine to reach speedily a desired or target characteristic value is selected, whereon control is performed such that the amount of the hydraulic fluid supplied to one of the actuating mechanisms which is destined for changing the characteristic of the valve selected is increased more than that of the hydraulic fluid supplied to the other actuating mechanism.
The reason why such control as mentioned above is performed may be explained by the fact that in case a plurality of valve timing control systems or mechanisms are actuated with one and the same hydraulic fluid supply source, the oil or hydraulic pressure to be supplied becomes lower (i.e., amount of the hydraulic fluid or oil decreases) when compared with the case a single valve timing control system or mechanism is actuated, which thus incurs lowering or degradation of the responsivity of the valve timing control means or mechanisms. Such being the circumstances, the selected valve timing control means or mechanism is actuated with priority over the other.
Thus, although sufficient responsivity can be ensured for the valve timing control means or mechanism actuated with priority, the other valve timing control means or mechanism(s) will suffer shortage of oil supply, incurring degradation in the responsivity thereof more or less.
SUMMARY OF THE INVENTION
In the light of the state of the art described above, it is an object of the present invention to provide a valve timing control system for an internal combustion engine in which a plurality of valve timing control means or mechanisms can be actuated with priority being imparted to a given valve timing control means or mechanism without degrading or impairing the responsivity of the other valve timing control means or mechanisms, to thereby enhance the responsivity of the valve timing control system on the whole.
Another object of the present invention is to provide the valve timing control system which can be implemented inexpensively in a structure similar to that of the conventional or existing valve timing control system without need for provision of additional means for achieving the functions contemplated with the present invention.
In view of the above and other objects which will become apparent as the description proceeds, there is provided according to a general aspect of the present invention a valve timing control system for an internal combustion engine, which system includes first and second valve means arranged for opening/closing an intake pipe which leads to a combustion chamber of an internal combustion engine and/or an exhaust pipe which extends from the combustion chamber, a first valve timing control means designed for causing a valve timing to change so that an actually advanced position of at least either one of the first and second valve means coincides with a desired or target advance position by regulating a control value, and a second valve timing control means designed for causing a valve timing to change so that an actually advanced position of the other one of the first and second valve means coincides with a target advance position by regulating a control value, wherein the control value for the first valve timing control means is changed in dependence on a controlling state of the second valve timing control means for thereby improving responsivity of the valve timing control system upon actuation of the first and second valve timing control means, respec

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