Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
2000-03-13
2001-11-27
Jeffery, John A. (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
Reexamination Certificate
active
06321700
ABSTRACT:
The invention relates to a method for controlling an electromagnetically actuatable adjustment device, in particular a periodically operating gas-reversing valve for internal combustion engines, as well as an adjustment device for realizing this method according to the preamble to the independent claims.
Electromagnetically actuatable adjustment devices, in particular adjustment devices for actuating gas-reversing valves on internal combustion engines are known from literature. A control method for such an adjustment drive is disclosed in the U.S. Pat. No. 5,636,601. The adjustment device comprises a tappet, which acts upon the adjustment member and is connected to an armature that is guided axially movable between the pole surfaces of two axially spaced apart electromagnets. Two adjustment springs that are effective in opposite directions hold the armature in an intermediate position, approximately in the center between the pole surfaces for the electromagnets, if no current is supplied to the electromagnets. The control is intended to adapt the adjustment device operation to various operating conditions.
The European Patent 0 77 038 A2, upon which this invention is based, discloses a method for operating an adjustment device by using a position sensor to determine the valve position. The start-up and shutdown periods for the closing and/or opening magnets are derived from different operating parameters, such as the adjustment angle for the crankshaft, the position of the drive pedal or the air-fuel-ratio. The position sensor records the valve position to avoid possible collisions with the piston.
Not solved, however, is the problem of eliminating the influence of variables that interfere with the control and are caused by the operation, in particular temperature fluctuations, changes in the viscosity of the oil for the gas-reversing valves, wear and tear on the adjustment device or soiling of the adjustment device. This can lead to a malfunction of the adjustment device, particularly to increased wear on the adjustment device, undesirable noise development and excess energy consumption. A reliable, continuous operation of the adjustment device cannot be ensured with this.
It is the object of the invention to specify a method for controlling an adjustment device, as well as a device for realizing said method, which can ensure a safe, continuous operation of the adjustment device and a reduction in the wear and tear of the adjustment device.
The above object generally is achieved according to the present invention by a method for operating an electromagnetically actuatable adjustment member, in particular a periodically operated valve for an internal combustion engines, including a connecting rod with at least one armature that is attached crosswise to its longitudinal axis, with the armature being moved between opposing pole surfaces of two electromagnets arranged at a distance from each other in an axial direction, two resetting springs that are effective in the axial direction connected to the connecting rod so that the armature is held in a center position between the electromagnets while the electromagnets are not supplied with current, wherein the method comprises: detecting the position of the adjustment member and/or the armature using a path sensor; and adjusting the current flow through the electromagnets such that the armature and/or the adjustment member move along a predetermined position/speed characteristic curve.
The position of the adjustment member and/or the armature is preferably detected by means of a path sensor and/or the speed of the adjustment member and/or the armature is determined from this position. The position and/or the speed are then transmitted to a regulating and control unit, which processes the signals into an actuation signal for the electromagnets, by taking into account the actual adjustment variables for the adjustment device, made available by a data source. The actuation signal influences the current flow through the electromagnets.
Especially preferred is the determination of position and/or speed by determining the inductance and/or the changes in the inductance of a coil, which is used as path sensor element. It is preferable if the coil is a component of an oscillating circuit, the frequency of which serves as measure for the inductance of the coil. The frequency advantageously is a measure for the position of the armature and/or the adjustment member. In particular, the frequency change represents as measure for the speed of the armature and/or the adjustment device.
It is favorable that the current flow through the electromagnets is adjusted with the method according to the invention, such that the armature and/or the adjustment member move securely along a predetermined position/speed characteristic curve. In particular, the current flow through the electromagnets is adjusted such that the speed at which the armature comes to rest on the pole surface is less than 3 m/s.
It is useful to select the coil shape such that the position/frequency connection is at least approximately linear. One preferred form of the coil is helical while another preferred form is cylindrical.
An electromagnetically actuatable adjustment device comprises an adjustment member, in particular a periodically operated gas-reversing valve for internal combustion engines, as well as a connecting rod that is connected force-locking with adjustment member. This connecting rod comprises an armature that is attached crosswise to its longitudinal axis and can be moved between opposite-arranged pole surfaces of two electromagnets in a magnet unit, which are arranged at an axial distance to each other. The adjustment device has two resetting springs that are effective in axial direction, so that the armature assumes a center position between the two electromagnets in the currentless state. According to the invention, the adjustment device is connected at least indirectly to a path sensor element, which determines the actual position of the armature and/or the adjustment member.
The position is preferably used to determine the speed of the adjustment member and/or the armature by means of a path sensor. Preferably, the path sensor is assigned to the connecting rod for the adjustment device or is connected to it and/or forms a component of this connecting rod.
The path sensor element of one preferred embodiment is arranged on the connecting rod end that is far from the adjustment member. In another preferred embodiment, the path sensor element is arranged directly adjacent to the magnet unit. The path sensor element of yet another preferred embodiment is arranged inside an electromagnet region that essentially does not contain a magnetic field, in particular inside the region closest to the connecting rod. Particularly preferred is an arrangement of the path sensor element between the pole surfaces of the electromagnets.
The path sensor for one preferred embodiment is a semiconductor sensor, particularly a Hall sensor. In another preferred embodiment, the path sensor is a magnetic sensor and for yet another preferred embodiment, it is an optical sensor. The path sensor of a further preferred embodiment is a capacitive sensor.
It is particularly preferable if the path sensor element comprises a coil, the inductance of which can be changed at least indirectly by the connecting rod. The path sensor of a particularly preferred embodiment is formed by a coil, into which the connecting rod of the adjustment device can plunge, at least at times. It is advantageous if the connecting rod is designed such that the coil inductance is influenced by the connecting rod.
The connecting rod end that is far from the adjustment member is advantageously provided with a metallic and/or magnetic material and/or a ferrite material.
It is particularly favorable that the actual contact position of the armature and/or the point in time at which the armature makes contact can furthermore be determined precisely by means of the path sensor.
The adjustment device can be connected to a control a
Ganser Thomas
Hein Nils
Hille Peter
Daimler-Chrysler AG
Jeffery John A.
Norman N. Kunitz
Patel Vinod D.
Venable
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