Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
1999-05-27
2001-03-27
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C335S261000, C335S281000, C335S301000
Reexamination Certificate
active
06206343
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a solenoid valve for use with a transmission device in automotive vehicles and, in particular, to a linear solenoid valve wherein a plunger is brought into linear movement when current is applied to a coil.
2. Description of the Prior Art
A conventional solenoid valve such as one disclosed in Japanese Patent Laid-open Publication No. Hei. 6 (1994)-123378 includes a coil wound around a bobbin, first and second yokes mounting thereon opposite sides of the bobbin, respectively, first and second bearings disposed in the respective first and second yokes, and a plunger disposed within the bobbin such that opposite ends of the plunger are supported by the respective first and second bearings, the plunger being brought into linear mode movement upon excitation of the coil.
For establishing smooth or reliable movement of the plunger, magnetic isolation between the plunger and each yoke must be formed in a uniform manner. To this end, in the conventional solenoid valve, an air gap is defined between the plunger and the yoke which is in the form of an annular ring in cross-section.
On the other hand, the plunger sometimes comes out of alignment with each of the yokes or an inclination condition may occur due to an assembly error of the bearing to the corresponding yoke.
Thus, the air gap should be of a sufficient width to prevent direct contact between the plunger and each yoke even though the plunger is brought into the inclination condition.
Such an air gap of sufficient width constitutes dead space in the solenoid valve, however, resulting in a solenoid valve larger in scale.
SUMMARY OF THE INVENTION
It is, therefore, one of the objects of the present invention to provide a solenoid valve without the foregoing drawbacks.
In order to attain the foregoing objects, the present invention provides a solenoid valve which comprises: a housing formed of a metal; a yoke accommodated in the housing and formed of magnetic material such that a non-magnetization portion is provided at a midway portion thereof; a coil wound around the yoke; a plunger arranged within the yoke coaxially with the yoke and moving in linear mode upon excitation of the coil; and a coating treatment made on at least one of an outer surface and an inner surface of the yoke so as to establish magnetic isolation evenly between the yoke and the plunger.
REFERENCES:
patent: 4826130 (1989-05-01), Griffith et al.
patent: 5509439 (1996-04-01), Tantardini
patent: 5538219 (1996-07-01), Osterbrink
patent: 6-123378 (1994-05-01), None
Kato Masaaki
Maeda Kazuhiko
Aisin Seiki Kabushiki Kaisha
Bonderer D Austin
Reed Smith Hazel & Thomas LLP
Shaver Kevin
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