Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1999-03-18
2000-10-24
Lo, Weilun
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9048, F01L 1300
Patent
active
061350745
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Field of the Invention
The invention concerns a tappet for a valve train of an internal combustion engine, said tappet being designed to be switched to different valve lifts including a tappet (1) for a valve train of an internal combustion engine, which tappet (1) can be switched to different valve lifts and is comprised of an outer annular section (2) which concentrically surrounds a circular section (5) which is axially displaceable relative thereto, both sections (2,5) being loadable in lift direction in the regions of their bottoms (3,6) by cams of different lifts, or at least one section being loadable by at least one cam in the lift direction, each of the sections (2,5) comprising in the region of its bottom (3,6) at least one reception (9,10) extending radially said receptions (9,10) being aligned to each other in a cam base circle phase, there being arranged in the reception (9) of the annular section (2) a first slider (11) which is displaceable by a servo means towards the reception (10) of the circular section (5), and said first slider (11), for realizing un uncoupling of the sections (2,5) extends with an inner end face (12) up to a position immediately in front of an annular surface (13) between the sections (2,5), and, for realizing a coupling of the sections (2,5), acts on a second slider (14) which extends through an entire length of the reception (10) of the circular section (5), so that both sliders (11,14) overlap the annular surface (13) by their peripheral surfaces (20,21) to establish a coupled state.
2. Background of the Invention
A tappet of the pre-cited type is known from DE-OS 43 14 619 and does not need to be described more closely here. A drawback of this tappet is that it comprises no means to exclude switching errors of its pistons which function as coupling means. The pressure-medium loaded pistons receive no information as to when it is technically appropriate to overlap the annular surface between the two parts of the tappet. Since such a tappet is switched, as a rule, in the base circle phase of the cam in which its two sections are aligned to each other in the region of their bottoms, it is possible, for example, at high engine rotation speeds, or due to other influences such as pressure medium fluctuations and the like that, when leaving the base circle of the cam, i.e. at the start of the run-on flank, the coupling means have not yet reached their position of coupling or uncoupling as the case may be. If, in this transition state, the coupling means concerned overlaps the annular surface between the two sections only slightly, cam lift on the outer section can break off leading to a destruction of components or to an extreme noise generation.
OBJECT OF THE INVENTION
It is therefore the object of the invention to create a tappet of the pre-cited type in which the mentioned drawbacks are eliminated and, more particularly, using simple means, to create a mechanism which excludes switching errors in the aforementioned operating states, that is to say, a mechanism which enables an axial displaceability of the coupling means only in the base circle phase.
SUMMARY OF THE INVENTION
The invention comprising a tappet (1) for a valve train of an internal combustion engine, which tappet (1) can be switched to different valve lifts and is comprised of an outer annular section (2) which concentrically surrounds a circular section (5) which is axially displaceable relative thereto, both sections (2,5) being loadable in lift direction in the regions of their bottoms (3,6) by cams of different lifts, or at least one section being loadable by at least one cam in the lift direction, each of the sections (2,5) comprising in the region of its bottom (3,6) at least one reception (9,10) extending radially said receptions (9,10) being aligned to each other in a cam base circle phase, there being arranged in the reception (9) of the annular section (2) a first slider (11) which is displaceable by a servo means towards the reception (10) of the circular section (5), and
REFERENCES:
patent: 5203289 (1993-04-01), Hara et al.
patent: 5343833 (1994-09-01), Shirai
patent: 5603294 (1997-02-01), Kawai
patent: 5651335 (1997-07-01), Elendt et al.
patent: 5694894 (1997-12-01), Allen
patent: 5709180 (1998-01-01), Spath
patent: 5782216 (1998-07-01), Haas et al.
patent: 5950583 (1999-09-01), Kraxner et al.
Ina Walzlager Schaeffler OHG
Lo Weilun
LandOfFree
Tappet for the valve gear mechanism of an internal combustion en does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tappet for the valve gear mechanism of an internal combustion en, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tappet for the valve gear mechanism of an internal combustion en will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1953575