Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1994-09-30
1996-03-05
Lo, Weilun
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9022, F01L 1300, F01L 126
Patent
active
054958318
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a valve actuation mechanism for an internal combustion engine with three inlet valves per cylinder which are actuated by cams of a camshaft by way of rocker arms.
In a known valve actuation mechanism of this type (e.g. DE-A 38 00 347), two first rocker arms are provided for actuating two inlet valves, which rocker arms interact with identical first cams so that in the first (lower) rotational speed range, all the inlet valves are actuated in an identical manner. Two second rocker arms are arranged between the first rocker arms or outside the same and these second rocker arms interact with different second cams. In one embodiment, each second rocker arm can be coupled to the adjacent first rocker arm. In another embodiment, the first rocker arms are connected together by a bridge and one or the other second rocker arm can be optionally coupled to the bridge and, by this means, to the two first rocker arms. For the actuation of three inlet valves, two first rocker arms interacting with identical cams are provided in a manner analogous to the second embodiment. These rocker arms are connected together by a bridge which acts on the three inlet valves. The two second rocker arms, which are arranged adjacent to one another and between the two first rocker arms, can be optionally coupled to the bridge and, by this means, to the two first rocker arms. In these known embodiments, the opening force exerted by the second cams in the coupled condition acts to one side of the first rocker arms or asymmetrically on the bridge connecting the first rocker arms together so that a tipping moment is generated which makes the decoupling, in particular, more difficult and, in the extreme case, can lead to jamming of the coupling means.
JP-A-60-216014 describes a valve actuation mechanism for an internal combustion engine with three inlet valves per cylinder which are actuated via rocker arms by cams of a camshaft. In this publication, each valve has its own rocker arm associated with it, which rocker arm is supported on its own rocker arm support and interacts with its own cam. No second rocker arms are provided to connect for valve control as a function of rotational speed, to the three rocker levers by coupling means.
SUMMARY OF THE INVENTION
The object of the invention is to create a valve actuation mechanism of the generic type, for an internal combustion engine with three inlet valves per cylinder, in which different control times can be effected for the three inlet valves in the first (lower) rotational speed range and the occurrence of tipping moments is avoided when the first and second rocker arms are coupled.
By using an appropriate configuration of the first cams, for example, it is possible to achieve a reduction in the idling rotational speed in the lowest rotational speed range, without impairing smooth running, by not opening the first inlet valve, by briefly opening the second inlet valve and by opening the third inlet valve for a longer time and with a late beginning of inlet. This is possible because the residual gas proportion, i.e. the quantity of burnt gases in the combustion space, is small due to the lack of overlap between the inlet and exhaust and because the small amount of idling mixture only enters the combustion space via the second and the third inlet valves, with different control periods, and a swirl is generated in the combustion space which contributes to optimum combustion. In the medium rotational speed range, all three inlet valves are in action so that by advancing the "inlet open" control time, a gain in torque is achieved and, because of the overlap between "inlet open" and "exhaust closed" now present, there is an internal exhaust gas recirculation which contributes to a reduction in the formation of oxides of nitrogen. In the upper rotational speed range, the first rocker arms are coupled to the second arms so that the valves can now be operated in accordance with the cam contour of the second cams--with a large lift, long openin
REFERENCES:
patent: 4762096 (1988-08-01), Kamm et al.
patent: 4799463 (1989-01-01), Konno
patent: 4809663 (1989-03-01), De Tomaso
patent: 4844023 (1989-07-01), Konno et al.
patent: 5101778 (1992-04-01), Fukuo et al.
Hannibal Wilhelm
Hubschle Peter
Paul Michael
Audi AG
Lo Weilun
LandOfFree
Valve actuating mechanism for an internal combustion engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Valve actuating mechanism for an internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Valve actuating mechanism for an internal combustion engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1406278