Valves and valve actuation – Electrically actuated valve – Solenoid having plural coils
Reexamination Certificate
1998-03-12
2001-02-06
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Solenoid having plural coils
C251S129150, C251S337000
Reexamination Certificate
active
06182942
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic actuator.
It is well known to utilize electromagnetic actuators, commonly referred to as solenoids, to control the operation of ancillary devices such as hydraulic valves. The principle of operation is well known and utilizes the magnetic field produced by a coil to cause displacement of a magnetizable core.
One such arrangement is shown in U.S. Pat. No. 5,513,832 to Becker in which a hydraulic valve is controlled by an armature mounted within a coil. The armature includes a magnetizable core supported on a central pin. The pin is guided for movement at one end in a conventional bearing. At the opposite end, a fluid-tight diaphragm is provided that includes a plate spring to provide a return force on the armature.
The accurate control of the ancillary device depends upon the repeatability of the response to a given input signal and the proportionality of that response. As such, the mechanical systems utilized to support an armature within the actuator have a significant effect upon the performance of the actuator and the device upon which it is acting. The coil not only imparts axial forces to the armature but also imparts radial forces. Conventional bushings of the type shown in the Becker patent are therefore susceptible to increased friction forces, particularly as the actuator wears, and radial misalignment that affects the proportionality of the response from given inputs.
It is therefore an object of the present invention to provide an actuator in which the above disadvantages are obviated or mitigated.
SUMMARY OF THE INVENTION
In general terms, therefore, the present invention provides an electromagnetic actuator having a body, an armature movable within the body, and a pair of supports extending between the body and the armature at longitudinally spaced locations to support the armature. A coil assembly is located in the body to encompass the armature. Each of the supports includes a resilient plate member extending normal to the longitudinal axis and secured to the body. Each plate member is arranged to flex in the direction of the longitudinal axis upon application of an electromagnetic force between the coil and the armature and thereby provide a bias to the armature.
Preferably the plate member is provided by a plurality of concentric rings interconnected by bridging members. The bridging members are circumferentially displaced to provide circumferentially extending beams between adjacent rings that allow for flexure of the plate upon application of an axial force.
REFERENCES:
patent: 3900822 (1975-08-01), Hardwick et al.
patent: 4396037 (1983-08-01), Wilcox
patent: 4494098 (1985-01-01), Haneda et al.
patent: 4635683 (1987-01-01), Nielsen
patent: 4988074 (1991-01-01), Najmolhoda
patent: 5234032 (1993-08-01), Kline et al.
patent: 5513832 (1996-05-01), Becker et al.
patent: 5787915 (1998-08-01), Byers et al.
patent: 5806565 (1998-09-01), Kadlicko
Keasel Eric
Ladas & Parry
Microhydraulics Inc.
Shaver Kevin
LandOfFree
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