Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1990-05-16
1992-06-09
Cross, E. Rollins
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
F01L 112, F01L 118, F01L 122
Patent
active
051197731
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an apparatus for operating the valves on internal combustion engines with the variable valve lift curve with a multimember, rotatable gear comprising the valve-guiding case, a rotating cam, driven by a crankshaft, connected to the case by a pivot joint, an intermediate member operated by the cam by a curve joint and a driven member, supported by a joint on the case and operatively connected to the intermediate member by a joint for transferring the movement to the valve.
BACKGROUND OF THE INVENTION
In order to reduce the load-dependent throttle losses on internal combustion engines, it is known to modify the valve opening times and valve lift curves during operation. In order to permit this modification, inter alia, multimember regulating or control gears are known (DE-A-27 53 197, DE-A-27 47 884, DE-A-30 06 619 and GB-A- 21 00 344). The known multimember gears suffer from the disadvantage of having a high constructional expenditure and a large space requirement and they generally constitute expensive constructions. In addition, in many cases, there is also a lack of rigidity due to the large number of members and joints and, in particular, their reciprocal construction and arrangement, so that it is frequently impossible to use them in rapidly rotating engines.
SUMMARY OF THE INVENTION
The aim underlying the invention resides in providing an apparatus of the aforementioned type which is inexpensive to manufacture and has a relatively small size and provides the necessary rigidity.
In accordance with the present invention, the intermediate member is supported by a curve joint on the case, with the curve of said curve joint, arranged on the intermediate member, having a portion forming a locking device and a control portion. A position of the curve supported on the case and belonging to the curve joint or the position of the pivot joint of the cam can be adjusted during operation.
In operation, the apparatus according to the invention only has three moving parts, namely, the rotary cam, the intermediate member and the driven member. Importance is attached to the adjustable curve joint with which the intermediate member is supported on the case, or the adjustable pivot joint of the cam for controlling the valve opening times, or the valve lift. These are determined by the curve located on the intermediate member as a part of the curve joint supporting said intermediate member, with the curve having a locking device for the load-free area and a controlled portion.
In a preferred embodiment, the curve of the curve joint supported on the case and which cooperates with the curve on the intermediate member is formed by a cylindrical surface. In the simplest case, it can be a cylindrical bolt, a roll, etc.
According to the invention, the joint is constructed between the intermediate member and the driven member and between the latter and the case as the pivot joint on each occasion.
The aforementioned embodiment is characterized by a particularly great rigidity and by a limited clearance and, as a result of its two pivot joints, constitutes a particular wear-resistant arrangement, which is especially suitable for rapidly rotating engines.
In accordance with features of the invention, the joint between the intermediate member and the driven member is constructed as a pivot joint and the joint between the driven member as a slider joint.
In this embodiment, the pivot joint between the intermediate member and the driven member is preferably formed by circular sliding faces, while the slider joint between the driven member and the case can be realized by the driven member being guided in a linearly displaceable manner in the case.
In the two aforementioned embodiments, the construction is advantageously such that the curve portion arranged on the intermediate member and forming the locking device (for the load-free area) is formed by an arc, whose center coincides with the pivot center of the pivot joint between the intermediate member and the driven member.
The a
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patent: 4714057 (1987-12-01), Wichart
patent: 4724822 (1988-02-01), Bonvallet
patent: 4911124 (1990-03-01), Bennett
Kuhn Peter
Schon Helmut
Cross E. Rollins
Kuhn Peter
Lo Weilun
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