Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
2003-01-21
2004-06-29
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
C123S090240, C251S129010, C251S129090, C251S129150, C335S220000
Reexamination Certificate
active
06755161
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a gas exchange valve drive for a valve-controlled combustion engine. In particular, the invention relates to a gas exchange valve where the reciprocating movement of the valve member is not effected and controlled by a cam shaft. Rather, the valve member is electrically actuated by the inventive gas exchange valve.
STATE OF THE ART
From DE 195 18 056 A1 a gas valve control with a gas exchange valve is known, which is actuated by an electromagnet arrangement. By means of a special configuration of the pole shaft of the electromagnet arrangement, a signal related to the movement of the armature is generated in the control line of the electromagnet arrangement. This signal can be evaluated for detecting any armature position without additional sensors. A considerable problem with the employment of an electromagnet arrangement for operating the valve is the high noise level developing upon reaching the respective end positions, the abrupt braking upon reaching the end positions, as well as the required high holding currents.
The same applies to differential electromagnet arrangements which have been proposed on several occasions, which are specifically subjected to an increasing current for achieving the required thrust of approx. 300-400 N for combustion engines of passenger cars. Therein, the valve which is biased by a spring arrangement initially performs an oscillating movement before an iron plate arranged at the valve shaft abuts the armature of the electromagnet arrangement so that a much lower holding current is required. Here, the maximum speed of the engine, however, is considerably limited. The start-up time upon starting is relatively long because of the required high force it takes some time for the valve arrangement to oscillate into its desired position.
From JP-A-3-92518 a drive means for a valve arrangement in combustion engines is known, wherein the stator is built from two approximately semi-cylindrical shells which comprise teeth, split both in the circumferential direction and in the longitudinal direction of each shell, facing towards the rotor. The individual teeth of each shell are each surrounded by a coil the center longitudinal axis of which extends in the radial direction. This results in a magnetic flux oriented in the radial direction, which originating from each of the plurality of teeth flows through the air gap between stator and rotor into the rotor.
An insofar corresponding configuration of the stator, the stator coils, and the rotor of a drive means for a valve arrangement in combustion engines is described in U.S. Pat. No. 5,129,369. In this case, too, teeth of the stator, which are split in the radial and tangential direction, are surrounded by a coil each whose_ center longitudinal axis extends in the radial direction.
EP 0 485 231 A1, too, shows a similar type of the stator design, the stator coils, and the rotor of a drive means for a valve arrangement in combustion engines. In this case, too, teeth of the stator, which are split in the radial and tangential direction, are surrounded by a radially oriented coil each.
These arrangements necessitate a very high manufacturing expenditure because the assembly of the coils around the individual teeth is difficult to realize. Moreover, the pole pitch which can be achieved with this construction is relatively large.
From WO98/55741 a valve arrangement for a valve-controlled combustion engine is known, with an electric travelling-field motor as an actuator for a valve member, which comprises a rotor coupled with a valve member and a stator. The stator is built from plates whose surfaces are oriented vertically to the direction of movement of the rotor. The stator has teeth facing towards the rotor which is designed as a synchronous or asynchronous rotor, each of which having a closed lateral cylinder area facing towards the rotor. Between two neighbouring teeth each of the stator, stator coil chambers are formed in which a coil each is arranged with is oriented parallel to the area of the plates.
From U.S. Pat. No. 6,039,014 a valve arrangement driven by a linear motor for a combustion engine is known. Here, the stator of the linear motor comprises several coils which are separated from each other by a ferromagnetic housing section each. A rotor is built from several sections of a permanent-magnetic material, between which sections are arranged, each consisting of a ferromagnetic material.
Further documents which show the technical background for the invention include, without claiming to be exhaustive: DE 33 07 070 A1; DE 35 00 530 A1; EP 244 878 B1; WO90/07635; U.S. Pat. No. 4,829,947; EP 377 244 B1; EP 347 211 B1; EP 390 519 B1; EP 328 194 B1; EP 377 251 B1; EP 312 216 B1; U.S. Pat. Nos. 4,967,702; U.S. Pat. No. 3,853,102; U.S. Pat. No. 4,829,947; U.S. Pat. No. 4,915,015; WO90/07637, WO90/07637; EP 328 195 A2.
Problem on Which the Invention is Based
All concepts which are described in the above mentioned documents have in common that they are unable to achieve the stroke, thrust, and dynamics required for gas exchange valves in combustion engines with adequate compact construction and high reliability for large series application in automotive engines. Moreover, known arrangements are manufactured in a very space consuming and expensive manner. Finally, these arrangement are also not suited for the application in high-speed (fast-running) combustion engines, because none of these arrangements is optimized with respect to the moved masses.
Invention Solution
For the elimination of these drawbacks, the invention teaches a gas exchange valve drive for a valve-controlled combustion engine with a linear motor as the actuator for a valve member, which is defined by the characteristics of Claim
1
.
Construction and Advantages of the Invention Solution
According to the invention the gas exchange valve drive for a valve-controlled combustion engine has a hollow cylindrical rotor to be coupled with a valve member, and a stator, with the rotor comprising permanent-magnetic rings arranged concentrically above each other, the stator being at least partially formed from a soft magnetic material and comprising at least one tooth facing towards the rotor, the stator comprising a radially inner magnetically conductive area and a radially outer magnetically conductive area, with the rings of the rotor being arranged between the inner area and the outer area of the stator, and the outer area of the stator having a C-shaped cross-sectional configuration in the radial direction in at least one partial section and comprising at least one stator coil.
The concept on which the invention is based consists in spatially “removing” the portion of the stator which effects the armature magnetomotive force, i.e. the coil area with the stator coil, from the portion generating the force of the linear motor, i.e. the tooth area of the stator. Compared to conventional linear motors where the stator coils are arranged between two teeth each of the stator, a considerably higher magnetomotive force of the armature can be achieved. This is dues to the fact that the coil is subjected to considerably less spatial restrictions due to the inventive design and can therefore to optimized to minimal (ohmic) losses- and the associated maximal magnetic field induction. By the dimensions of the permanent-magnetic rings in the direction, of movement of the rotor or the dimensions of a tooth of the stator in the direction of movement of the rotor, respectively, a pole pitch is defined which is smaller than the dimension of the stator coil in its longitudinal direction.
Simultaneously, the rotor magnetic pole/stator tooth arrangements generating force or movement, respectively, are concentrated so that these are not interrupted by stator coils. This allows a very small pole pitch which in turn effects a high force density. In addition, the inventive arrangement allows partial strokes of the valve member. Thus, it is possible with a combustion engine equipped with the inventive gas exc
Gründl Andreas
Hoffmann Bernhard
Compact Dynamics GmbH
Denion Thomas
Riddle Kyle
Wood Herron & Evans L.L.P.
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