Valves and valve actuation – Electrically actuated valve – Remote or follow-up control system for electrical actuator
Patent
1989-09-14
1991-09-10
Rosenthal, Arnold
Valves and valve actuation
Electrically actuated valve
Remote or follow-up control system for electrical actuator
25112908, 25112915, 13762548, F16K 3106
Patent
active
050467026
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a solenoid device, and more precisely relates to such solenoid devices as an electromagnetic valve which has a coil and a plunger, a displacement sensor, etc.
BACKGROUND TECHNOLOGY
Conventionally, an electromagnetic valve, which is one type of solenoid devices, has a plunger, which is movably provided in a center hole of an electromagnetic coil in the axial direction thereof. A valve body is provided at the front end of the plunger. There is shown a proportional control valve for controlling the amount of flow in FIG. 15.
A proportional control valve 900 has an electromagnetic coil 904, which covers the outer face of a plunger 902. There are provided yokes 906 and 908 around the electromagnetic coil to enclose the magnetic circuit. The plunger 902 is biased to the electromagnetic coil 904 by leaf springs 910 and 912. The force working on the plunger 902 is transmitted to a valve body 916 by a slide pin 914.
Upon passing the electric current through the electro-magnetic coil 904, the magnetic force corresponding to the intensity of electric current, voltage or number of pulse biases the plunger 902 downward to press the valve body 916 which is connected to a diaphragm. The amount of flow at an exit 920 can be controlled under the governor theory.
An example of displacement sensors is disclosed as Japanese Patent Provisional Publication (Kokai) No. 61-172011. This displacement sensor has a coil and a diaphragm. A magnetizable body, which can be slidable in the coil, is attached to the diaphragm. The end face of the magnetizable body is arranged outside of the coil. The change of the reactance (or the frequency) of the coil caused by displacement of the magnetizable body which is connected to the diaphragm is measured as the amount (or pressure) of displacement of the diaphragm.
DISCLOSURE OF THE INVENTION
However, the above stated solenoid devices have the following problems.
In the proportional control valve, the magnetic circuit closes via the yokes and the plunger. The magnetic force works to the lower end of the plunger because the cross sectional area of the plunger is the same at any position. But the magnetic force working to the yokes and the plunger changes due to the rule of Coulomb because of the gap therebetween. Therefore, the degree of the opening of the valve body curvilinearly changes when the degree of the opening of the valve body is changed by adjusting the intensity of the electric current (or the voltage), so that it is difficult to control or to adjust precisely. To adjust the change of the degree linearly, an additional mechanism (e.g. spring) should be required), so that manufacturing cost will be increased.
While, in the displacement sensor, when the end face of the magnetizable body comes up to the opposite end face of the coil, the reactance of the coil quickly changes becoming the gap zero, so that a large amount of change of the reactance cannot be gained once the end section of the magnetizable body has been inserted into the center hole of the coil. Therefore, the range in which the amount of displacement of such displacement body as a diaphragm can be gained as the change of the reactance of the coil is limited from the position at which the end face of the magnetizable body is closed to the opposite end face of the coil to the position at which the end face of the magnetizable body begins insertion into the center hole of the coil. Namely, the stroke of the displacement is quite limited in narrow a range, so that a large amount of the displacement cannot be measured.
The characteristic curve of the stroke of the magnetizable body and the reactance of the coil is curvilinearly (i.e. the curve of secondary degree) changed, so that an expensive microprocessor having a large memory capacity is needed to convert the change of the reactance into the amount of the displacement.
Therefore, the object of the present invention is to provide a solenoid device such as an electromagnetic valve which can precisely control the amou
Kobayashi Takanori
Miyazawa Shozo
Kabushiki Kaisha Kambayashi Seisakujo
Rosenthal Arnold
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