Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Reexamination Certificate
1999-05-14
2001-02-06
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
C123S090110, C251S129160, C335S251000
Reexamination Certificate
active
06184767
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims the priority of German Application No. 198 22 907.0 filed May 22, 1998, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
An electromagnetic actuator for operating a setting member (for example, a cylinder valve of art internal-combustion engine) has at least one electromagnet—but frequently two spaced electromagnets—energizable in a controlled manner. The electromagnet is associated with an armature which is connected with a guide rod and which is further operatively connected with the setting member. Upon energization of the electromagnet the armature is moved into an end position against the force of a resetting spring and the armature again assumes its initial position when the electromagnet is de-energized. In case two electromagnets and thus two resetting springs are used, during alternating energization of the electromagnets, the armature is reciprocated in accordance with the frequency of the alternating energization. The duration of the energization of an electromagnet also determines the period in which the armature is held at the pole face of the respective attracting electromagnet and, accordingly, the setting member which is operated by the armature is held in the respective switching position.
An electromagnetic actuator of the above-outlined type having two electromagnets is used in particular for operating a cylinder valve of an internal-combustion engine. In such a construction the resetting springs, serve as respective opening and closing springs for the cylinder valve. Because of the necessarily large forces required to maintain the cylinder valve in its closed position and, also, to open the cylinder valve against the gas pressure within the engine cylinder, strong compression coil springs are required which are loaded (compressed) parallel to their geometrical central axis. Such an axis, at the same time, represents the line of motion of the armature, and if the setting member is a cylinder valve, such an axis also represents the line of motion of the cylinder valve.
The end faces of a compression coil spring of the above-outlined type have a planar annular configuration to ensure a satisfactory seating of the spring on the associated spring support.
Because of manufacturing tolerances, however, the effective operating path line of the resulting force of the compressed coil springs generally does not coincide with the geometric central axis. As a result, the Force is not evenly distributed over the spring seating surface, but is introduced at a location preferred by the structure. An eccentric location of the point of force introduction causes, in the seating surface of the compression spring, reaction forces which may be demonstrated by the existence of transverse forces and tilting torques. Such torques are transmitted from the spring support to the armature and the armature guide rod and cause, in addition to a rotation of the armature about its axis of motion, a rocking (tilting) motion of the armature transversely to the Line of motion. As an undesired result, the armature strikes the components laterally bordering the armature chamber, and also, stochastic frictional effects are introduced. A rotation of the armature about its longitudinal axis is particularly disadvantageous in actuator constructions in which the armature is not of rotationally symmetrical configuration but is, for example of rectangular outline. Because of such a tilting motion and as a function of the location of force introduction, the release behavior of the armature from the pole face changes as the electromagnet is de-energized.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved electromagnetic actuator of the above-outlined type from which the discussed disadvantages are eliminated.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the electromagnetic actuator includes an electromagnet and an armature movable toward the electromagnet by an electromagnetic force generated upon energization of the electromagnet. The armature is connectable to a setting member displaced as a function of armature motions. The electromagnetic actuator further has a resetting spring which opposes the electromagnetic force and which has a first end supported in a housing and a second end; and at least one jointed connecting arrangement interposed between the resetting spring and the armature for supporting the armature on the second end of the resetting spring.
The armature which is usually connected with a spring seat disk of the armature guide rod and to which thus the resetting forces of the spring are applied, is, by virtue of the interpositioned jointed structure, disconnected from the resetting spring so that rotational motions appearing during the loading and relaxing of the compression coil spring are transmitted to the armature to a negligible extent—if at all—due to the frictional forces in the region of the joint. Geometrical deviations of the effective path of the resulting spring force relative to the geometric central axis of the spring can no longer act as a tilting force on the armature via the armature guide rod. The joint is to be designed such that it has at least two degrees of freedom. In both earlier-noted uses in which the joint has three degrees of freedom, the joint permits a motion of the resetting spring relative to the armature in all three coordinates, that is, in addition to a tilting motion relative to the central axis, it also permits a rotation about the axis without force transmission. Expediently, the joint is formed by a spherical joint which is preferably free from transverse forces.
According to an advantageous feature of the invention, the resetting spring is a compression coil spring and the center of the joint lies on the geometrical center line of the spring.
According to a further feature of the invention, the resetting spring is supported on the housing by a spherical joint arrangement. Such an arrangement further minimizes interfering effects of the resetting spring on the armature because both spring ends, by virtue of the given degrees of freedom of the joint, may freely move relative to the armature and/or the housing.
According to a further advantageous feature of the invention, the joint includes a supporting yoke for the resetting spring. Such a supporting yoke may be a plate or a transverse member which, on the one side, constitutes the seating surface for the resetting spring and, on the other side, constitutes a part of the spherical joint. In such a construction it is feasible to provide the supporting yoke with a bore into which a suitably dimensioned steel ball is pressed and which cooperates with a corresponding counterface of the housing and/or the armature guide rod. The arrangement may further be such that the supporting yoke is either planar or is provided with cup-shaped depressions which are engaged by the spherical counter element or the correspondingly configured spherical end of the armature guide rod.
REFERENCES:
patent: 3813625 (1974-05-01), Kinsella
patent: 5813653 (1998-09-01), Esch et al.
patent: 5868108 (1999-02-01), Schmitz et al.
patent: 5878704 (1999-03-01), Schebitz et al.
Duesmann Markus
Esch Thomas
Pischinger Martin
Donovan Lincoln
FEV Motorentechnik GmbH
Kelemen Gabor J.
Nguyen Tuyen T.
Venable
LandOfFree
Electromagnetic actuator having a joint-supported resetting... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electromagnetic actuator having a joint-supported resetting..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic actuator having a joint-supported resetting... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2599443