Electrical generator or motor structure – Dynamoelectric – Linear
Utility Patent
1998-07-23
2001-01-02
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
Utility Patent
active
06169342
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims the priority of German Application No. 297 13 167.2 filed Jul. 24, 1997, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
Electromagnetic actuators are essentially formed of at least one electromagnet which has a solenoid and a yoke provided with at least one pole face, as well as an armature which is coupled with a setting member to be operated by the electromagnetic actuator and which is connected to at least one resetting means. The armature is moved from a first setting position determined by the resetting means into a second setting position by electromagnetic forces in an energized state of the solenoid. The second setting position is determined by the abutting relationship between the armature and the pole face of the energized electromagnet.
Electromagnetic actuators of the above-outlined type are used, for example, for controlling cylinder valves in piston-type internal-combustion engines. Such actuators include two electromagnets between which electromagnetic forces cause the armature to reciprocate against the force of two resetting means, for example, resetting springs, as the electromagnets are alternatingly energized and de-energized. By an appropriate control of the individual actuators which operate the respective cylinder valves, the intake and outflow of working medium may be effected such that the operating process may be optimally controlled as a function of the momentary operational requirements. Electromagnetically operated actuators for cylinder valves are disclosed, for example, in U.S. Pat. No. 4,455,543.
To ensure a high control accuracy, a relatively high energy has to be applied to the armature for its capture at a pole face of the electromagnet. A high energy input, however, is coupled with a diminishing operational reliability, because as a further problem the phenomenon of armature rebounding appears in a more pronounced manner. This problem is caused by the fact that the armature impinges on the pole face at a high speed and may rebound either immediately or after a short delay. Such rebound phenomena in the control of cylinder valves adversely affect the operation of a piston-type internal-combustion engine. Even in the absence of rebound, the impact between armature and pole face generates relatively strong, undesired noises. For reducing such noises, it has been proposed to provide the pole faces with an elastically deformable layer or to provide hollow spaces in the region of the pole faces and/or the cooperating counterfaces of the armature. As a result, shortly before the full engagement of the armature at the pole face, the air enclosed in the hollow spaces is compressed and thus the impact of the armature is dampened. Providing such hollow spaces is involved, however, with a substantial technological outlay and requires, for example, high-precision finishing operations.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved electromagnetic actuator of the above-outlined type in which noise generation is reduced while maintaining the impact energy unchanged.
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 composed of a yoke provided with a pole face and a solenoid which is carried by the yoke and which is energizable with electric current for generating electromagnetic forces. An armature coupled to a setting member (such as a cylinder valve of an internal-combustion engine) is movable into engagement with and away from the pole face of the yoke. A resetting spring is connected to the armature for opposing movements of the armature toward the pole face. The yoke and/or the armature is at least in part elastically deformable toward the armature and the yoke, respectively.
In this arrangement advantage is derived from the fact that the armature is connected to a central guide rod extending perpendicularly to the armature surface and that the magnetic force which increases exponentially with increasing approach of the armature to the pole face, is effective essentially in the edge zone of the armature and the yoke, while the counteracting resetting force which, as a rule, increases linearly, has its principal effect in the region where the armature is connected to the guide rod. Thus, by using an essentially plate-like, for example, 3 mm thick armature which may be circular, square or rectangular, and which is made of a soft-magnetic, elastically deformable material, during the approach of the armature to the pole face under the effect of the above-described forces, a deformation of the armature occurs such that its edge zone is slightly bent in the direction of motion. As a result, the armature first touches the pole face with its edge zone and lies only thereafter with its full surface area against the pole face as urged by the large magnetic force while, at the same time, it undergoes a reverse deformation, regaining its original shape. As a result, noise generation upon impact is reduced.
The principle according to the invention may also be implemented by rendering the yoke elastically deformable, for example, by forming the yoke of welded core laminae. In such a case too, the magnetic forces appearing between the yoke and the approaching armature result in deformations which lead to an initial contact between the armature and the pole face only over partial regions of the eventually engaging surfaces. The position of the partial regions for the initial contacting may be predetermined by an appropriate shaping of the pole surface and/or the associated armature surface.
Thus, the invention may be implemented by a variety of combinations, such as rigid yoke/elastically deformable armature, elastically deformable yoke/rigid armature and elastically deformable yoke/elastically deformable armature. The selection of the specific combination and/or configuration to be used depend on the given geometry of the pole face and the armature as well as on the effective magnetic forces.
According to an advantageous feature of the invention, the pole face of the electromagnet has a dish-shaped depression, whose cross section is such that it is adapted to the spatial deformability of the plate-shaped armature, predetermined by the edge contour thereof. It is an advantage of this arrangement that as the edge region of the armature impinges on the edge region of the dish-shaped depression of the pole face, upon further approach of the armature (as urged by magnetic forces), not only is the deformation, obtained during the earlier approach, counteracted and eliminated but until a total full-face engagement of the armature on the pole face takes place, the armature is elastically deformed in the opposite direction, thus generating an additional resetting force which reduces the impact until the full-face engagement. It is a further advantage in this arrangement that for introducing a counter motion to release the armature subsequent to the de-energization of the holding current, the additional resetting force which is present by virtue of the above-noted deformation of the armature in the position of full-face engagement, a faster release of the armature and thus a shortening of the “sticking period” of the armature at the pole face are achieved.
Whether the armature or the yoke is elastically deformable, it is an advantageous feature of the invention to provide, in the pole face, a convex central region projecting toward the armature. The dimensions of such convex projecting part are determined dependent upon the elastic deformability of the armature and/or the yoke.
According to yet another feature of the invention, the armature is a solid body of soft-magnetic iron and the yoke is expediently formed of welded core laminae.
Thus, in the design of the armature as concerns its strength, on the one hand magnetic conditions have to be fulfilled and, on the other hand, the elasticity or spring conditi
Kley Philip
Nehl Jakob
Schmillen Karl
Schneider Matthias
FEV Motorentechnik GmbH & Co. KG
Jones Judson H.
Kelemen Gabor J.
Ramirez Nestor
Venable
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