Radiant energy – Ionic separation or analysis – Static field-type ion path-bending selecting means
Reexamination Certificate
2002-10-24
2004-07-06
Hirsch, Paul J. (Department: 3754)
Radiant energy
Ionic separation or analysis
Static field-type ion path-bending selecting means
C123S090110
Reexamination Certificate
active
06759640
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 2001-328900 filed on Oct. 26, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of controlling a current applied to an electromagnetically driven valve such as an intake valve and an exhaust valve of an internal combustion engine and a control system.
2. Description of Related Art
Conventionally, operation of an internal combustion engine is controlled by opening and closing an intake valve or an exhaust valve by a cam of a camshaft synchronously driven by a crankshaft. With recent progress of computer-controlled operation in the field of internal combustion engines, operation of an internal combustion engine is increasingly controlled by opening and closing an intake valve or an exhaust valve by an electromagnetic actuator. The use of the electromagnetic actuator enables the valve to be opened and closed at various timings. As a result, various methods of controlling the operation of an internal combustion engine (especially for a vehicle) have been proposed.
Basically, in the intake valve or the exhaust valve of an internal combustion engine, a disc-like armature is attached to a valve shaft, and a pair of electromagnets for opening and closing the electromagnetically driven valve are disposed so as to be apart from the armature by a distance equivalent to a sum of an opening/closing stroke of the valve and a thickness of the armature, respectively such that those valves face with each other. The valve is opened by applying electric current to the electromagnet for opening the valve (hereinafter referred to as the valve opening electromagnet) so as to attract the armature thereto. The valve is closed by applying electric current to the electromagnet for closing the valve (hereinafter referred to as the valve closing electromagnet) so as to attract the armature thereto. In general, as the armature is formed from a paramagnetic material such as a soft iron, each of the valve opening and valve closing electromagnets generates only an attraction force to attract the armature, not a repulsion force. As the magnetic attraction force is inversely proportional to the square of the distance, and the valve opening/closing stroke is relatively long, a size of the valve opening electromagnet, thus, has to be increased to generate the attraction force sufficient to attract the armature released from the valve closing. Likewise a size of the valve closing electromagnet has to be increased to generate the attraction force sufficient to attract the armature released from the valve opening electromagnet to the valve closing electromagnet. The electromagnetically driven intake valve or exhaust valve as aforementioned is provided with a pair of springs for urging the armature at a neutral position of the valve opening/closing stroke. More specifically, one of the pair of springs, serving as the valve opening spring, forces the armature released from the valve closing electromagnet toward the direction away from the valve closing electromagnet. The other spring, serving as the valve closing spring, forces the armature released from the valve opening electromagnet toward the direction away from the valve opening electromagnet. The aforementioned structure forms a vibration system in which a valve element including the armature, the valve shaft to which the armature is attached, and the valve body is suspended between those springs. The valve can be opened and closed by adjusting the current applied to the valve opening electromagnet and the valve closing electromagnet using resonance of the vibration system. Therefore, there is no need to increase each size of those electromagnets. Assuming that the displacement of the valve body or the armature resulting from the valve opening/closing operation is expressed as a lift amount, the lift amount is correlated with the moving speed of the valve body or the armature as shown in FIG.
1
. In order to establish the relation as shown in
FIG. 1
, the current applied to the electromagnets may be correlated with the lift amount as shown in FIG.
2
. As a result, the lift amount changes with times as shown by a solid line of FIG.
3
. In the case where the electromagnet has a small capacity, and the valve movement goes out of the timing at which the resonance of the vibration system can be used for assisting the valve operation, the valve may be stuck at the neutral position of the valve opening/closing stroke. The aforementioned stuck state is typically known as “step-out”.
Japanese Patent Laid-Open Publication 11-294209 discloses alternate application of current to the first and the second electromagnets synchronously with a natural period of the vibration system to gradually increase the amplitude of the armature so as to recover the valve from the step-out state. Generally reverse current is applied to the electromagnet to which application of current is interrupted so as to extinguish the residual magnetic field upon switching the opening/closing operation of the electromagnetically driven valve. Then the inductance of the valve against the reverse current is detected. If the detected inductance is smaller than a predetermined value, it is determined that the electromagnet has failed to attract the armature and, thus, the valve has been brought into the step-out state.
According to the aforementioned method, it is determined whether the armature has been attracted to the electromagnet on the basis of the inductance of the electromagnet that releases the armature against the reverse current applied thereto for extinguishing the residual magnetic field. If the inductance is smaller than a predetermined value, it is determined that the armature has not been attracted to the electromagnet and, thus, it is determined that the step-out has occurred. The valve may be recovered from the step-out by taking a required procedure so as to avoid any failure in operating the internal combustion engine owing to the step-out.
However, according to the aforementioned method, the step-out of the valve is generally detected with a delay corresponding to a period taken for operating a cycle of opening or closing the valve.
According to the aforementioned method in which the step-out is regarded as the state where the valve is stuck at a neutral position between the valve opening/closing stroke. However, there may be a case in which the valve body fails to open/close in accordance with the normal timing even if the valve is held at the closing or the opening position. Such behavior of the valve that indicates possibility of the step-out may be recovered to the normal condition after performing at least one cycle of the valve opening/closing operation.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of controlling current applied to an electromagnetically driven valve and a control system so as to detect a failure in the valve as well as to recover the detected failure at the appropriate timing.
In a control method of current applied to an electromagnetically driven valve including a first electromagnet, a second electromagnet, an armature that is attracted by one of the first and the second electromagnets after being released from attraction of the other electromagnet so as to move a valve body of the electromagnetically driven valve between a valve opening position and a valve closing position, and a spring that holds the armature at a neutral position between a position where the armature is attracted by the first electromagnet and a position where the armature is attracted by the second electromagnet, it is determined whether a displacement of the armature is equal to or smaller than a predetermined threshold value after an elapse of a predetermined time from start of switching operation of the electromagnetically driven valve between an opening state and a closing state. When it is determined that the displacement is e
Katsumata Shoji
Matsumoto Isao
Mizuta Tametoshi
Nishida Hideyuki
Ogiso Makoto
Hirsch Paul J.
Oliff & Berridg,e PLC
LandOfFree
Method of controlling current applied to electromagnetically... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of controlling current applied to electromagnetically..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of controlling current applied to electromagnetically... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3220412