Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2002-08-06
2004-09-07
Hirsch, Paul J. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C335S255000
Reexamination Certificate
active
06786467
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to electric-actuated control valves, such as valves for controlling flow of fluids in automotive vehicle engine systems. In particular, the invention relates to improvements for increasing the useful stroke of such a valve by enhancing the force vs. stroke characteristic of the valve actuator. Examples of such valves are exhaust gas recirculation (EGR) valves and fuel cell valves.
BACKGROUND OF THE INVENTION
The actuator of certain control valves of automotive vehicle engine systems comprises a solenoid that comprises an electromagnet coil and a stator having an air gap at which magnetic flux acts on an armature. The armature motion is transmitted to a valve element to control flow through a passage of the valve. Armature motion is resisted by a return spring that acts on the armature, either directly or via the valve element, to bias the armature toward a position that causes the valve element to close the passage.
The stator air gap is defined by an upper pole piece that is disposed at an upper end of the coil and a lower pole piece at a lower end of the coil. The pole pieces have respective annular hubs that fit into an interior space bounded by the coil, approaching each other from opposite ends of the coil. The juxtaposed ends of the two hubs are spaced apart to define the air gap as a generally annular space within which the armature is centered and along which the armature can travel. Electric current in the coil creates magnetic flux that passes from one hub through a portion of the air gap to the armature, through the armature, and back across another portion of the air gap to the other hub. The flux creates an electromagnetic force on the armature, and the axial component of that force acts to displace the armature along the centerline of the solenoid against the resistance of the return spring. In order to operate the valve from closed to open, the solenoid must apply a force that is greater than the sum of the bias force being applied by the return spring and any other forces acting on the valve.
For achieving improved control, it is desirable that the valve actuator be able to deliver increasing force over an increased stroke length. However, certain constraints that are imposed on certain automotive vehicles, especially mass-produced vehicles that are subject to governmental regulation, make it impossible, impractical, and/or uneconomical simply to use a larger solenoid. Accordingly, it is believed that a valve that is capable of delivering increasing force over an increased stroke length, without accompanying increases in size and weight that would be deemed unacceptable, would be useful to automotive vehicle manufacturers in complying with constraints imposed on the vehicles that they manufacture.
SUMMARY OF THE INVENTION
The present invention relates to a valve that is capable of delivering increasing force over an increased stroke length, without accompanying increases in size and weight that would be deemed unacceptable.
One general aspect of the invention relates to an electric-actuated control valve for controlling flow of fluid in an automotive vehicle engine system. The valve comprises a valve body comprising a passage having an inlet port for receiving fluid and an outlet port for delivering fluid. A mechanism selectively positions a valve element to selectively restrict the passage. The mechanism comprises a solenoid actuator comprising a bobbin having a tubular core of non-ferromagnetic metal and ferromagnetic pole pieces at axial ends of the tubular core. An electromagnet coil comprising a length of magnetic wire is wound on the tubular core between flanges of the pole pieces. The pole pieces form portions of a magnetic circuit for magnetic flux created by electric current in the coil and comprise hubs that protrude into the tubular core and have juxtaposed ends defining an air gap within the tubular core through which the magnetic flux passes between the pole piece hubs. The mechanism further comprises an armature that is guided for motion axially of the tubular core for positioning the valve element and that comprises ferromagnetic material for conducting magnetic flux created at the air gap when electric current flows in the coil to cause an axial component of electromagnetic force to be exerted on the armature for positioning the valve element.
Another aspect relates to the solenoid actuator itself.
Still another aspect relates to a method of making the valve and the actuator.
The accompanying drawings, which are incorporated herein and constitute part of this specification, include a presently preferred embodiment of the invention, and together with a general description given above and a detailed description given below, serve to disclose principles of the invention in accordance with a best mode contemplated for carrying out the invention.
REFERENCES:
patent: 3670274 (1972-06-01), Ellison
patent: 4518938 (1985-05-01), Bartholomaus et al.
patent: 4725802 (1988-02-01), Johnson et al.
patent: 5237980 (1993-08-01), Gillier
patent: 6220277 (2001-04-01), Blain
patent: 6474320 (2002-11-01), Modien
Hirsch Paul J.
Siemens VDO Automotive Inc.
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