Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
2001-05-15
2002-07-02
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
C251S129100, C335S255000
Reexamination Certificate
active
06412456
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a control system for controlling an electromagnetically operated valve, and more particularly to an electromagnetic valve control system which is capable of executing a soft landing of a movable member onto an electromagnet in a valve open/close control.
Lately, there are proposed various electromagnetic valve operating systems that employ an electromagnetic actuator comprised of a movable member, a pair of electromagnets and a pair of springs so as to reciprocatingly operate intake and exhaust valves of an internal combustion engine. Generally, it is preferable that a movable member of such a valve operating system is softly landed on an electromagnet while ensuring a required motion performance. A Japanese Patent Provisional Publication No. (Heisei)11-159313 discloses a landing method for softly landing a movable member on an electromagnet in an electromagnetic valve operating system. Such soft landing in this system is achieved by temporally switching off the electromagnet during a period between a switch-on moment of the electromagnet and the landing moment of the movable member. Further, in order to realize a further accurate landing control of an electromagnetic valve unit including a valve and an electromagnetic actuator, there is proposed a control method employing a characteristic representative of a vibration system of the electromagnetic valve unit.
SUMMARY OF THE INVENTION
However, the characteristic of the vibration system of the controlled electromagnetic valve unit is varied according to an operating condition. Particularly, a friction in the electromagnetic valve unit is largely affected by a temperature since the friction largely depends on a characteristic of rubricating oil whose viscosity is varied according to the change of temperature. Therefore, it is difficult to stably execute a required landing control only by a preset characteristic representative quantity.
It is therefore an object of the present invention to provide a control system for certainly executing a soft landing control of an electromagnetic valve unit by employing an actual characteristic of a vibration system of the electromagnetic valve unit.
An aspect of the present invention resides in a valve control system comprising an electromagnetic valve unit and a controller. In this system, the electromagnetic valve unit comprises a valve, a pair of electromagnets arranged in spaced relationship from one another in axial alignment with the valve so as to form a space, a movable member axially movably disposed in the space between the electromagnets and interlocked with the valve, and a pair of springs biasing the movable member so as to locate the movable member at an intermediate portion of the space when both of the electromagnets are de-energized. The controller is connected to the electromagnetic valve unit and energizes and de-energizes each of said electromagnets to reciprocatingly displace the valve. The controller is arranged to detect a characteristic of a free vibration of a vibration system in the electromagnetic valve unit when both electromagnets are de-energized, and to estimate at least one of a friction quantity and a spring constant of the vibration system on the basis of the detected characteristic of the free vibration.
Another aspect of the present invention resides in a method for controlling an electromagnetic valve unit, the electromagnetic valve unit being arranged to operate a valve by electromagnetically controlling a pair of electromagnets so as to displace a movable member disposed in a space between the electromagnets which receiving biasing force of a pair of springs. The method comprises detecting a characteristic of a free vibration of a vibration system in the electromagnetic valve unit when both electromagnets are de-energized; and estimating at least one of a friction quantity and a spring constant of the vibration system on the basis of the detected characteristic of the free vibration.
REFERENCES:
patent: 4905506 (1990-03-01), Lebershausen
patent: 6047672 (2000-04-01), Hanai
patent: 11-159313 (1999-06-01), None
Kawabe Taketoshi
Kumaki Hiroshi
Nakajima Shigeru
Taniguchi Ikuhiro
Corrigan Jaime
Denion Thomas
Nissan Motor Co,. Ltd.
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