This invention has been created without the sponsorship or funding of any federally sponsored research or development program.
Solenoid systems for electromagnetic actuation of engine valves are well known in the art. These systems are required to move a valve between open and closed positions that are far apart in a short time. Previous designs have relied on mechanical springs to store part of the energy in the system in order to lessen the power requirement of the solenoid and to improve control of valve's acceleration and deceleration. It would be desirable to develop a system that would make it practical to eliminate the mechanical spring used in an electromagnetic valve actuator.
Since the magnetic attractive force between two parallel surfaces decreases as the distance increases by the square of the distance and the force is proportional to the area of the surfaces, the magnetic interaction between conventional flat to parallel surfaces employed and prior art designs impose serious limitations. It would be desirable to develop geometric techniques that would increase the effective power of the solenoid system and improve energy efficiency.
Thus, existing actuators employ mechanical springs that complicate and increase the cost of the actuators and contribute to maintenance difficulties. Furthermore, existing actuators employ the solenoid systems that are not efficient producers of force and therefore also complicate increase the cost of the actuators and contribute to maintenance difficulties.
These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the present invention to provide an actuator which increases electromagnetic effectiveness over the range of movement.
Another object of this invention is to provide an actuator this simple in construction in design.
A further object of the present invention is to provide an actuator which is compacted in design and therefore allows a high degree of flexibility in integrating the actuator into mechanical systems.
It is another object of the invention is to provide an actuator that allows precise and reproducible motion.
It is a further object of the invention to provide an actuator that is capable of being manufactured of high quality and at a low cost, and which is capable of providing a long and useful life with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto, it being understood that changes in the precise embodiment of the invention herein disclosed may be made within the scope of what is claimed without departing from the spirit of the invention.
This invention is a valve actuator for controlling movement of poppet valves (inlet valve and exhaust valve) and internal combustion engines. The actuator includes an armature is mounted on the stem of the valve. The armature has a convex surface on its front and a convex on the rear. In one embodiment the surfaces would be tapered with a wedge shape. The taper would be approximately eighteen degrees from the axis of the valve stem. The actuator also includes electromagnets with concave surfaces that conformed to the convex surfaces of the armature. The electromagnets are arranged so that they can be selectively activated to cause movement of the valve. The complementary geometry of the armatures and magnets enhance the effectiveness of the magnetic field cost by the electromagnets on the armature.
The character of the invention, however, may best be understood by reference to one of its structural forms, as illustrated by the accompanying drawings, in which:
a shows magnetic circuits for a prior art valve actuator,
b shows magnetic circuits for a valve actuator of the present invention,
a shows a front elevation sectional view of valve actuator with tapered armature, said actuator embodying the principles of the present invention, in the valve closed position,
b shows a front elevation sectional view of valve actuator with tapered armature, said actuator embodying the principles of the present invention, in the valve open position,
c shows a front elevation view of an armature and valve stem used in a valve actuator embodying the principles of the present invention,
d shows a right side elevation view of an armature and valve stem used in a valve actuator embodying the principles of the present invention,
e shows a front elevation sectional view of an armature and valve stem used in a valve actuator embodying the principles of the present invention, the section as viewed along line AA of
f is a plan view of a coil assembly and actuator body embodying the principles of the present invention,
g is a front elevation view of a coil assembly and actuator body embodying the principles of the present invention,
h is a right side elevation view of a coil assembly and actuator body embodying the principles of the present invention,
i is a front elevation view of the left coil in the coil assembly and actuator body shown in
j is a left side elevation view of the coil assembly and actuator body shown in
k is a sectional front elevation view of the coil assembly and actuator body shown in
l is a sectional front elevation view of the coil structure shown in
m is a sectional front elevation view of the coil structure shown in
a shows a front elevation view of an alternate valve and armature arrangement for use when the valve itself is nonmagnetic,
b shows a right side elevation view of the arrangement shown in
c shows a sectional front elevation view of the arrangement shown in
a shows a magnetic circuit for a prior art actuator used for operating engine valves. Coil 1a is wound on magnetic member 2a. Magnetic member 2a is attached to two magnetic members 3a. The coil 1a and the members 2a and 3a form the coil assembly. Magnetic member 4a, which is the movable part, is attracted to the coil assembly by magnetic attraction. Flux lines 9a depict the path of the magnetic flux. The flux lines traverse air gap 7a and air gap 10a in their circuit. Surfaces 5a and surface 8a define the area of air gap that must be traversed. In practice, surface area 10a is equal to the sum of the two surface areas 5a. The distance that separates the magnetically attractive surfaces is typically about 8 mm. The part of the flux path that is in the magnetic members is typically about 48 mm. For a given magneto motive force A (mmf), the solenoid system of
b shows a magnetic circuit of the present invention. The two drawings
In
Ft=Fa sin a
The result of this is that the solenoid system of
In one embodiment of this invention, the motion of the valve @@ from its open position to its closed position, is controlled through a the magnetic action of the coils by an electronic valve position controller @@. In one embodiment of this invention, the controller receives a signal from the valve position sensor @@. The signal is generated by the physical relationship between the tapered end 6 of the valve 15 and the valve position sensor coil 13. The signal is an accurate representation of the relative position of the valve in its range of movement. This signal allows the controller to recalibrate the position of the valve at its closed position during every valve opening cycle, and thereby more accurately control the movement of the valve. In this way, compensation for thermal expansion is determined and applied.
In one embodiment of the invention, the coupling 5 may be a rigid connection between the valve 15 and the armature shaft 4. This rigid connection is possible because the accuracy of the valve position sensor @@ allows a valve position controller @@ to recalibrate the position of the valve at its closed position during every valve opening cycle. In this way, compensation for thermal expansion is determined and applied, so the coupling 5 need not be expandable.
In some applications, it is possible to have the valve 15 extend through the armature and have no coupling 5 outside of the valve actuator. An example of this is when the valve material is titanium.
It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.
This application claims the benefit under 35 U.S.C. §119(e) of: U.S. Provisional Application No. 60/551,199 filed Mar. 8, 2004, U.S. Provisional Application No. 60/566,112 filed Apr. 28, 2004, U.S. Provisional Application No. 60/574,414 filed May 24, 2004, U.S. Provisional Application No. 60/578,548 filed Jun. 10, 2004, U.S. Provisional Application No. 60/605,943 filed Aug. 31, 2004, and U.S. Provisional Application No. 641,225 filed Jan. 4, 2005, and this application claims the benefit under 35 U.S.C. §120 of: an Patent Cooperation Treaty application filed on the same day (Mar. 7, 2005) as this application, entitled “Induction Sensor”, by the same inventors as this application, all of which applications are hereby incorporated by reference.
Number | Date | Country | |
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60551199 | Mar 2004 | US | |
60566112 | Apr 2004 | US | |
60574414 | May 2004 | US | |
60578548 | Jun 2004 | US | |
60605943 | Aug 2004 | US | |
60641225 | Jan 2005 | US |