Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
1999-10-29
2001-07-10
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
C251S129100, C251S129160
Reexamination Certificate
active
06257182
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates an electromagnetic drive system for opening and closing intake valves and exhaust valves of an internal combustion engine for automobiles.
A Japanese Patent Provisional Publication No. 8-21220 discloses a typical electromagnetic drive system constituted by an electromagnetic drive mechanism and a control unit. The electromagnetic drive mechanism is basically constituted by an armature directly connected to an intake valve, a pair of electromagnets and a pair of springs. The control unit receives information indicative of an engine operating condition from various sensors and outputs a control current to the electromagnetic drive mechanism according to the engine operating condition indicative information. The electromagnets are alternately energized and de-energized to repeatedly open and close the intake valve according to the engine operating condition indicative information.
SUMMARY OF THE INVENTION
However, this conventional electromagnetic drive system has several characteristics to be improved. For example, although the attracting force of the electromagnet is radically increased according to the decrease of a distance between the armature and the electromagnet, spring force of the spring against the attracting force of the electromagnet is linearly increased. Therefore, at a terminating period of a valve-closing stroke, the intake valve may radically collide with the valve seat, and at a terminating period of a valve-opening period, the armature may radically collide with the electromagnet. Further, since this conventional electromagnetic drive system is integrally installed to the intake valve, assembly of this system to an engine requires complicated steps.
It is therefore an object of the present invention to provide an improved electromagnetic drive system which solves the above-mentioned drawbacks.
An electromagnetic drive system according to the present invention functions to repeatedly open and close a valve of an internal combustion engine and comprises an electromagnetic drive mechanism and a damper mechanism. The electromagnetic drive mechanism comprises a pair of electromagnets, an armature disposed between the pair of electromagnets and a pair of springs setting the armature at a neutral position between the electromagnets when both the electromagnets are de-energized. The electromagnets are alternately energized and de-energized according to a control signal. The damper mechanism is interlocked with the electromagnetic drive mechanism and functions to decrease a speed of displacement of the valve at a terminating period of each of a valve-closing stroke and a valve-opening stroke of the valve.
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Hara Seinosuke
Hibi Tsutomu
Miyazato Yoshiaki
Nakamura Makoto
Todoroki Katsuhisa
Foley & Lardner
Lo Weilun
Unisia Corporation
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