Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
1999-11-16
2001-01-09
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
Reexamination Certificate
active
06170445
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic actuating system of an internal combustion engine, and particularly to an electromagnetic actuating system of an internal combustion engine which actuates an intake valve or an exhaust valve by cooperation of an electromagnetic force generated by an electromagnet and a resilient force generated by a spring.
2. Description of the Related Art
Conventionally, as disclosed in Japanese Laid-Open Patent Application No. 59-213913, there is known a solenoid valve having an engine valve which functions as an intake valve or an exhaust valve of an internal combustion engine. An armature is connected to the engine valve. Hereinafter, the engine valve and the armature are referred to as a movable part.
An upper electromagnet and an upper spring are disposed above the armature, and a lower electromagnet and a lower spring are disposed below the armature. The armature is held at a neutral position between the upper and lower electromagnets by the upper and lower springs. Each of the upper and lower electromagnets generates an electromagnet force which attracts the armature by being supplied with an exciting current.
According to the above-mentioned conventional solenoid valve, the movable part can be moved toward the upper electromagnet by supplying an exciting current to the upper electromagnet. Similarly, the movable part can be moved toward the lower electromagnet by supplying an exciting current to the lower electromagnet. Thus, according to the conventional solenoid valve, it is possible to actuate the intake valve or the exhaust valve to be closed and opened by alternately supplying exciting currents to the upper and lower electromagnets at appropriate timings.
In the conventional solenoid valve, when the movable part is in a fully closed position or a fully opened position, the movable part can promptly start being actuated in response to a request by cooperation of the electromagnetic force generated by the upper or lower electromagnet and a resilient force generated by the upper or lower spring. On the other hand, when power supply to the solenoid valve is shut off, the movable part is held at a neutral position between the fully closed position and the fully opened position since neither the upper electromagnet nor the lower electromagnet is energized. In this state, the armature is spaced away from both the upper and lower electromagnets and resilient forces of the upper and lower springs exerted on the armature are balanced. Thus, in order to start actuating the movable part from the neutral position, it is necessary to exert an electromagnetic attracting force on the armature spaced away from the electromagnets in a situation where the resilient forces of the springs cannot be used. Therefore, when the movable part is at the neutral position, electric power to be supplied to the electromagnet becomes large, and, additionally, it is difficult to promptly operate the solenoid valve.
For this reason, in the above-mentioned conventional solenoid valve, exciting currents are alternately supplied to the upper and lower electromagnets with a period corresponding to a natural vibration period of the movable part when the internal combustion engine is started. According to this technique, the movable part can be moved from the neutral position to the fully closed position or the fully opened position by a resonance phenomenon of the movable part. Hereinafter, the above-mentioned process of, when the engine is started, moving the movable part to the fully closed or opened position by exciting a natural vibration of the movable part is referred to as an initial actuation.
However, when the initial actuation is performed, a large operating sound is generated by a vibration of the movable part. Additionally, since exciting currents must be alternately supplied to the upper and lower electromagnets, power consumption of the solenoid valve becomes large.
In view of these disadvantages of the initial actuation, Japanese Laid-Open Patent Application No. 10-138110 discloses a solenoid valve which can maintain the movable part in the fully closed position without performing the initial actuation. This solenoid valve includes a solenoid which is provided to the upper spring at one end thereof opposite to the armature. When the solenoid is not energized, the upper spring is upwardly retracted. In this state, the armature is in contact with the upper electromagnet. On the other hand, when the solenoid is energized, the upper spring is downwardly pressed toward the armature by the solenoid. In this state, the armature is held in the neutral position. Thus, according to the above-mentioned structure, it is possible to hold the movable part in the fully closed position by simply de-energizing the solenoid.
However, when the engine is operating, the movable part must be actuated by the upper and lower electromagnets with the neutral position being a center of movement of the movable part. Thus, when the engine is operating, it is necessary to energize the solenoid so as to maintain a state where the upper spring is pressed toward the armature, resulting in increased power consumption of the solenoid valve.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electromagnetic actuating system of an internal combustion engine which can hold an armature in a fully closed position or a fully opened position when the engine is started while obviating a necessity of the initial actuation and effectively reducing power consumption of the system.
The above-mentioned object of the present invention can be achieved by an electromagnetic actuating system of an internal combustion engine, comprising:
an engine valve which functions as an intake valve or an exhaust valve of the internal combustion engine;
an armature which moves with the engine valve;
an electromagnet which attracts the armature in a direction of movement of the engine valve by being supplied with a current;
a spring which presses the armature away from the electromagnet;
a permanent magnet which can exert a magnetic attracting force between the armature and the electromagnet; and
a stop-time current controller which shuts off the current supplied to the electromagnet, after controlling the current supplied to the electromagnet until the armature is attracted to the electromagnet by the magnetic attracting force of the permanent magnet, when a request to stop the internal combustion engine is generated.
In this invention, the controller shuts off a current to the electromagnet after the armature is attracted by the permanent magnet to the electromagnet. Since the permanent magnet can exert a magnetic attracting force between the armature and the electromagnet, the state in which the armature is attracted by the permanent magnet to the electromagnet can be maintained while the electromagnet is being de-energized, that is, while the internal combustion engine is not operating. A position of the armature in the state where the armature is attracted to the electromagnet corresponds to the fully closed position or the fully opened position. Thus, the armature can be held in the fully closed position or the fully opened position when the internal combustion engine is started next time without performing the initial actuation. Therefore, according to the invention, it is possible to prevent an increase in an operating sound and power consumption of the system due to execution of the initial actuation. Additionally, since it is unnecessary to supply a current to the electromagnetic coils so as to hold the armature, electric power is not consumed while the internal combustion engine is not operating. Further, since the magnetic attracting force of the permanent magnet contributes to a force for attracting the armature toward the electromagnet while the internal combustion engine is operating, a current to be supplied to the electromagnet can be reduced. Thus, power consumption of the system can be further saved.
Other objects a
Asano Masahiko
Hattori Hiroyuki
Iida Tatsuo
Izuo Takashi
Kenyon & Kenyon
Lo Weilun
Toyota Jidosha & Kabushiki Kaisha
LandOfFree
Electromagnetic actuating system of 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 Electromagnetic actuating system of internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic actuating system of internal combustion engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2447962