DE102008030194A1 - Electromagnetic actuating drive operating method for actuating switching valve of internal-combustion engine, involves controlling and/or regulating trapping current supplied to coil in dependence of another current flowing by coil - Google Patents

Abstract

The method involves switching an anchor (2) of an electromagnetic actuating drive (1) between two end positions, where the drive comprises an electromagnetic coil (5) for holding the anchor at a trapping block (4) attached to one of the end positions. A trapping current is adjusted for switching the anchor from one of the end positions assigned to a released block, into the other end position assigned to the trapping block. The current supplied to the coil is controlled and/or regulated in dependence of another current flowing by the coil. An independent claim is also included for an electromagnetic actuating drive for actuating a switching valve.

Description

The The present invention relates to a method for operating a electromagnetic actuator and an associated actuator.

at the so-called "impulse charging" of internal combustion engines can fast-switching valves are used. Such a fast-switching Valve can do this in a single cylinder of the internal combustion engine Fresh gas feeding Fresh gas line may be arranged upstream of an intake valve. By utilizing fluid dynamic Effects can be in the respective fresh gas line pressure waves generate, with the help of which the loading of the respective cylinder can be improved. For Such fast-switching valves are also other applications known. For example, they can be used for an exhaust gas recirculation rate to control. For this purpose, the respective fast-switching valve, for example be arranged in an exhaust pipe of the internal combustion engine, and Although downstream of a sampling point for recirculating exhaust gas. By short-term, clocked closing the valve may be in the exhaust pipe at the sampling point an increased pressure be generated, which is the return of Exhaust favors. These are extremely short switching times for switching from one a closed position assigned end position and one associated with an open position End position required. The switching times of the fast switching Valves are in the range of switching times of the gas exchange valves. For example, a fast-switching valve during an opening phase an intake valve at least once opening and closing. The Switching times can be less than 10 ms and in particular in the range between 2 and 5 ms are. Likewise, for the control of the exhaust gas recirculation rate arranged such valve in a common fresh gas line be, from which divided the fresh gas to several cylinders of the internal combustion engine becomes. Here, the air cycle valve upstream or downstream of a Launch point for be recirculated Be disposed exhaust gas in this common fresh gas line. in the Operation of the internal combustion engine can arise in the fresh gas flow pressure waves. With the help of the fresh gas side arranged fast switching valve can be such pressure waves strengthen or generate. This can affect the pressure at the point of introduction what can be used to control the exhaust gas recirculation rate.

One Such quick-switching valve needs a corresponding, fast-switching actuator for actuating the valve. Such an actuator preferably has a switchable between two end positions and with a reset device in a lying between the end positions rest position anchor and at least one electromagnetic coil for holding the armature at one of the respective end position associated stop. The anchor can over a shaft with a valve member of the valve are drive-coupled. The end positions of the armature can therefore be the open position and the closed position Assign the valve member. If the respective coil is the anchor in which holds an end position, is the reset device, which is preferably a spring device, in particular a torsion spring, acts, cocked. When releasing the anchor from the one end position drives the restoring force of the spring device the anchor towards the rest position. This is the in the spring device stored potential energy in kinetic energy of the anchor transformed. In other words, the anchor is accelerated. At the Passing through the rest position is the potential energy of the restoring device Completely converted into kinetic energy of the anchor. Accordingly moved the anchor continues towards the other end position. This is the kinetic energy of the anchor back into potential energy the return device converted, whereby the anchor is braked. To the anchor must be able to catch the stop assigned to the other end position the respective, the catching stop associated coil in time be energized. With the help of the catching coil, energy conversion losses, such as B. heat, be compensated. For another, with the help of the catching coil ensure that the anchor remains on the catching stop. Furthermore, the anchor should not bounce on the catching stop. In addition, should the impact velocity of the anchor on the catching stop preferably be small to the wear and tear the noise preferably to keep low. This makes the control or regulation the respective coil as extremely complex, as contradictory Requirements must be realized. Furthermore, the Periods that for the Control or Regulation process available stand, extremely short, which complicates said operations in addition. Come in addition, that the boundary conditions of the actuator during operation, in particular in conjunction with an internal combustion engine, can change. For example, the Change the temperature of the actuator. The reset device can be a temperature-dependent characteristic have, resulting in the temperature-dependent restoring forces and thus temperature-dependent anchor speeds result. Further, depending from the operating state of the internal combustion engine the flow resistance, against which the respective valve member are moved by means of the armature must, vary. Thus, must from the actuator varying adjusting forces can be realized.

The present invention is concerned with the problem for an actuator of the aforementioned type or for an associated Be drive method to provide an improved embodiment, which is characterized in particular by the fact that less wear and less noise and / or an improved adaptation to changing operating parameters can be realized.

This Problem is inventively things the independent one claims solved. Advantageous embodiments are the subject of the dependent Claims.

The The invention is based on the general idea, the power supply to respective catching coil not in dependence predetermined fixed Times, but in dependence to control the current flowing through the respective catching coil current or to regulate. The invention uses the knowledge that the approaching the catching plot Anchor strongly influences the current flow through the catching coil, so that over the current flow through the catching coil conclusions about the position of the armature possible are. This is a simple way of estimating the Anchor position during the important final phase of his movement possible, resulting in the adaptation of the Energizing the catching coil can be used. Especially let yourself the catching coil thereby depending on the actual, within the respective switching operation present position of the Anker energized, which in particular an individual adaptation changing Operating parameters possible is.

Corresponding an advantageous embodiment can be provided on the respective catching coils the catching current to adjust until a quotient of current change per time change at the current flowing through the respective catching coil current a predetermined first threshold reached, with the respective catching coil is switched to a freewheel, as soon as said quotient reaches the first threshold, until the said Quotient reaches a predetermined second threshold. At the respective catching coils will then set a lashing current as soon as said quotient reaches the second threshold. This embodiment based on the idea the current flowing through the respective catching coil is about to strike of the anchor at the catching stop comparatively strong drops. This is explained by that At this stage of the armature movement, there is a gap between the armature and the catching stop so far reduced that a gap bridging magnetic flux between the anchor and the catching stop strongly increases with decreasing gap. By the first threshold can thus be recognized that the anchor in a final phase of his Movement path is located in which no additional attractive magnetic forces required are to bring the anchor safely to the catching stop to the plant. Another energization of the catching coil would be in this phase of movement accelerate the anchor too much. Accordingly, upon reaching the first threshold, the power supply of the fishing coil off. The current flow through the respective catching coil has at Impingement of the anchor at the catching stop a turning point, since In this case, the gap between the anchor and catching stop closed becomes and thereby the magnetic flux and in the consequence also the current through the catching coil change. In particular from the impact of the anchor on the catching stop the decrease the coil current less strong. Upon reaching the second threshold, whose Quotient in the course of the current a section after the said inflection point can represent it can be assumed that the armature bears against the catching stop. Accordingly, upon reaching the second threshold, the Festzurrstrom be set. The tightening current is dimensioned in this way, that he bounces, so again lifting the anchor from the stop prevented or at least disabled. It is important that the Times to turn off the capture current and turn on the Festzurrstroms are not fixed, but depending on the flowing through the catching coil Amount of electricity to be switched. This is within the individual Switching a certain adaptation to changing boundary conditions possible.

Further important features and advantages of the invention will become apparent from the Dependent claims, from the drawings and from the associated description of the figures the drawings.

It it is understood that the above and the following yet to be explained features not only in the specified combination, but also in other combinations or alone, without to leave the scope of the present invention.

preferred embodiments The invention are illustrated in the drawings and in the following description explains where like reference numerals refer to the same or similar or functionally identical components relate.

It show, in each case schematically,

1 a simplified, circuit diagram-like schematic diagram of an actuator,

2 a simplistic schematic diagram of a switching valve,

3 a diagram illustrating the timing of a coil current.

Corresponding 1 includes an electromagnetic actuator 1 an anchor 2 , between two end positions indicated here by broken lines I and II is switchable and with the help of a reset device 3 in a rest position shown by a solid line III is biased. In his final positions I . II is the anchor 2 each at a stop 4 at. In its rest position III is the anchor 2 in the position shown between the two stops 4 , The attacks 4 is at least one electromagnetic coil 5 assigned. In the example shown is every stop 4 such a coil 5 assigned. The anchor 2 consists of a suitable ferromagnetic or soft magnetic material.

In the example shown is the anchor 2 around a rotation axis 6 rotatably arranged to move between its end positions I . II to be adjusted back and forth. It is clear that even a linear actuator 1 it is conceivable that the respective anchor 2 bidirectional between his attacks 4 or end positions I . II is adjustable.

The reset device 3 consists in the example shown essentially of a torsion bar 7 that is coaxial in a hollow shaft 8th extends, at which the anchor 2 rotatably attached.

Corresponding 2 can the actuator 1 about his wave 8th with a valve member 9 be connected to drive. With the help of the actuator 1 can thus the valve member 9 around the axis of rotation 6 rotatably operated. The actuator 1 is with a controller 10 coupled, in particular the coils 5 can be controlled to the valve member 9 between one of the one end position I assigned closed position and one of the second end position II to be able to adjust the assigned open position. The arrangement of actuator 1 and valve member 9 forms a switching valve 11 , with the aid of which the flow-through cross-section of a conduit 12 can be controlled. The switching valve 11 can thereby a line section 13 involve in the line 12 is used. Likewise, the valve member 9 directly into the line 12 be used. For example, it is the line 12 to an exhaust pipe or to a fresh gas line of an internal combustion engine.

With the help of the actuator 1 Thus, for example, a fast-switching switching valve 11 be actuated, the valve member 9 is rotatably adjustable between its switching positions. Likewise, it is basically possible, with the aid of the aforementioned linear actuator 1 to drive a linear adjustable between its switching positions actuator. For example, gas exchange valves can be operated with such a linear actuator.

In the diagram of 3 the abscissa defines the time rail, while the ordinate defines a voltage U and a current I through the respective coil 5 and a path φ and the velocity ω of the armature 2 represents. This is a course 14 an induction voltage or indicator voltage of the releasing coil 5 shown in a lower part of the diagram as well as a gradient 15 of the coil current I through the catching coil 5 and a course 16 of the coil current I through the releasing coil 5 , In contrast, the armature travel φ and the armature speed ω are shown in an upper portion of the diagram.

Several parallel vertical lines characterize different times t throughout the diagram, while in the lower half several horizontal lines represent certain current values I and in the upper half three horizontal lines represent the two end positions I . II and the rest position III of the anchor 2 represent. The rest position III associated horizontal line also represents the value 0 (zero) for the anchor speed (ω = 0).

In the following, a switching process is explained in more detail, in which the anchor 2 from the one end position I in the other end position II is switched.

During this switching process, the armature moves 2 according to a course 16 from the one end position I to the second end position II , Its velocity ω changes according to a course 17 ,

At the time t ₀ , a signal for switching the armature takes place 2 , Until this time t ₀ is at the releasing coil 5 a holding current I _hold set. Likewise is due to the releasing coil 5 until the time t ₀ a corresponding, constant voltage. At time t ₀ , the energization of the releasing coil 5 switched off. Accordingly, the current falls through the releasing coil 5 according to the course 16 strong. At the same time, the voltage drops at the releasing coil 5 according to the course 14 strong. At a time t _on , the zero crossing of the course takes place 16 that is, by the releasing coil 5 flowing electricity. At this time t _on , a so-called counter-pulse is started, in which the releasing coil 5 temporary is energized with reverse polarization. Accordingly, the coil current drops through the releasing coil 5 continue to negative values. With the time t _on the time measurement begins within the described here Control algorithm.

After a predetermined time period from the time t _on the time is t _off prior to the counter pulse, so the commutated energization of releasing coil 5 is ended. As a result, the current through the releasing coil approaches according to the course 16 from below again to the value 0.

The at the releasing coil 5 applied voltage U _ind initially decreases during this time to a minimum 19 and then rises to a maximum 20 back to. At time t ₀ is the at the releasing coil 5 applied voltage equal to zero. However, due to Lenz's rule, induction is reciprocally proportional to the degrading magnetic field of the releasing coil 5 , At the minimum 19 The decrease of the induction voltage and the increase of the applied voltage counterbalance each other. Thereafter, the applied voltage predominates and rises to the maximum 20 at. Subsequently, the voltage decreases again, which is attributed to induction processes, the formation of a gap and by increasing the gap between the armature 2 and releasing stop 4 is returned. In other words, upon reaching the Maximus 20 raises the anchor 2 from the releasing stop 4 from. By measuring the at the releasing coil 5 applied voltage can thus be determined the time t ₁ , to which the armature 2 from the releasing stop 4 takes off.

After a predetermined and adjustable period of time t ₂ -t ₁ , the time t _{2 is} present. At time t ₂ is at the catching coil 5 a Vorbestromung performed, whereby the coil current waveform 15 has a strong rising edge. This Vorbestromung is carried out for a predetermined period of time t ₃ -t ₂ , which may also be adjustable, but is usually fixed. Subsequently, from the time t ₃ on the catching coil 5 a capturing current set I _catcher. Specifically, the catch current I _{Fang is} regulated or chopped. When chopping, the current value is adjusted by quickly switching on and off a higher current. Accordingly, the current curve has 15 in this area a wavy structure.

From the time t ₃ monitors the controller 10 a quotient of the current change ΔI per time change Δt in the course of the current 15 through the catching coil 5 , As soon as this quotient ΔI / Δt reaches a predetermined and in particular fixed first threshold value Q ₁ , the catching coil becomes 5 no longer energized with the catch current I _Fang , but switched to a freewheel, during which no energy supply to the catching coil 5 he follows. The first threshold Q ₁ is chosen so that it does not occur during the chopping of the _catch current I _Fang , but can then be detected when the current through the catching coil 5 decreases sharply and no longer reaches the value of the catch current I _catch by choppers. This is the case when the anchor 2 the catching plot 4 has come so far that the magnetic flux over the then correspondingly reduced gap between the armature 2 and catching stop 4 significantly enlarged. As soon as the first fast value Q _{1 has been} reached, there is the time t ₄ at which the energization of the catching coil 5 is turned off. Accordingly, the current flow through the catching coil decreases 5 according to the course 15 with the time t ₄ from having a steep flank. The steeply sloping flank but after a short time flatter and flatter. In between there is a turning point in the course 15 the current through the catching coil 5 , This turning point is caused by the impact of the anchor 2 on the catching plot 4 , For monitoring the contact between armature 2 and catching stop 4 watch the control 10 continue the current flow 15 through the catching coil 5 , As soon as the quotient ΔI / Δt reaches a predetermined and, as a rule, fixed second threshold value Q ₂ , control passes 10 assume that the anchor 2 in the meantime at the catching stop 4 has come to the plant. The second threshold value Q ₂ is smaller in magnitude than the first threshold value Q ₁ . As soon as the second threshold Q _{2 is} reached, the time t _{5 is} present.

From the time t ₅ is at the catching coil 5 a tightening current I _fixed set. Said Festzurrstrom I _Fest in the example shown is smaller than the catch current I _Fang . With the help of the lashing current I _Fest is trying to bounce the anchor 2 at the catching stop 4 to avoid what can happen due to the impulse laws. The Festzurrstrom I _Fest is gechoppert appropriate.

The lashing current I _fixed is set for a predetermined period of time t ₆ -t ₅ . Subsequently, from the time t ₆ on the catching coil 5 a holding current I _hold adjusted, preferably chopped.

Of particular importance here is that the time t ₄ -t _{3 is} not fixed, but that the switching off of the catch current I _{catch is} determined by the presence of the first threshold Q ₁ , which thereby determines the time t ₄ . Furthermore, it is important that the time period t ₅ -t _{4 is} not fixed, but is determined on the one hand by the variable time t ₄ and on the other hand by the variable time t ₅ , the latter depending on reaching the second threshold value Q ₂ . Accordingly, in the method presented here, the respective catching coil 5 supplied current I as a function of by the respective catching coil 5 flowing current I controlled or regulated.

An embodiment in which the time t ₅ resulting from the second threshold value Q ₂ is used to adapt the next or another subsequent switching operation is particularly advantageous. As a result, the respective current switching process is effectively evaluated and used for an adaptation of at least one subsequent Umschaltvor gangs. This allows the controller 10 adjust the switching operations to changing environmental conditions.

For example, at time t ₅ by the respective scavenging coil 5 flowing minimum current I _{Min be} determined. Furthermore, an actual difference between the capture current I _Fang and the minimum current I _Min and with a desired difference of these currents I _Fang and I _Fest can be compared. The desired difference can be determined, for example, by means of field tests and test benches and predefined. Depending on this desired-actual comparison of the mentioned current differences, the catch current I _Fang can now be adapted for the next or another subsequent switching process. If the actual difference is too small, the catch current I _{Fang is} increased. If the actual difference is too large, the catch current I _catch is reduced accordingly. If the difference corresponds approximately to the desired difference, the catch current I _{catch / catch is} left constant. In each case, the respective adaptation of the catching current can take place in each case by a predetermined fixed change value, which simplifies the adaptation.

Additionally or alternatively, with the aid of the time t ₅ , an actual difference between this time t ₅ and an earlier time t can be determined and compared with a desired difference of these times. Depending on this desired-actual comparison of the time differences can then be adapted accordingly for the next or another subsequent switching operation of the respective earlier time t, ie in particular kept constant or moved to early or delayed. This adaptation also preferably takes place by a predetermined fixed change value. The mentioned time differences define time periods, whereby the beginning of the respective time span can be shifted by the adaptation of the respective earlier time t. The time t that can be displaced with the aid of this adaptation can be, for example, the time t ₃ , starting at the catching coil 5 the catch current I _{catch is} set. Likewise, it may be at the earlier time to the time t ₂ , starting from the catching coil 5 the pre-energization is performed.

The desired difference for the currents I is expediently chosen such that a catching current I _Fang results therefrom, which is dimensioned such that the minimum current I _{Min which is} likely to be present at time t ₅ is presumably greater than the holding current I _Halt .

Claims (11)

Method for operating an electromagnetic actuator ( 1 ), one between two end positions ( I . II ) and with a reset device ( 3 ) into one between the end positions ( I . II ) lying rest position ( III ) prestressed anchors ( 2 ) and at least one electromagnetic coil ( 5 ) for holding the anchor ( 2 ) at one of the respective end positions ( I . II ) associated stop ( 4 ), in which the switchover of the armature ( 2 ) from one, the releasing stop ( 4 ) associated end position ( I . II ) into the other, the catching stop ( 4 ) associated end position ( I . II ) from a point in time (t ₃ ) on the respective stop ( 4 ) associated coil ( 5 ) a catching current (I _catch ) is set, - whereby that of the respective catching coil ( 5 ) supplied current (I _catch , I _fixed ) as a function of the respective catching coil ( 5 ) flowing current (I) is controlled and / or regulated. Method according to claim 1, characterized in that - at the respective catching coil ( 5 ) the catching current (I _catch ) is set until a quotient of current change (ΔI) per time change (Δt) reaches a predetermined first threshold value (Q ₁ ), - that the respective catching coil ( 5 ) is freewheeled as soon as said quotient (ΔI / Δt) reaches the first threshold (Q ₁ ) and until said quotient (ΔI / Δt) reaches a predetermined second threshold (Q ₂ ), - at the respective catching coil ( 5 ) a Festzurrstrom (I _fixed ) is set as soon as said quotient (.DELTA.I / .DELTA.t) reaches the second threshold (Q ₂ ). Method according to Claim 2, characterized in that a time (t ₅ ) at which said quotient (ΔI / Δt) reaches the second threshold value (Q ₂ ) is determined and used to adapt the next or another subsequent switching operation. A method according to claim 3, characterized in that - at the time (t ₅ ) through the respective catching coil ( 5 ) minimum current (I _min ) is determined, - that an actual difference between the catch current (I _catch ) and the minimum current (I _min ) is determined and compared with the desired difference of these currents (I _catch , I _min ), that depending on the target-actual comparison of the Dif With reference to these currents (I _catch , I _min ), the catch current (I _catch ) is adapted, in particular kept constant or increased or decreased, for the next or another subsequent switchover, in particular by a predetermined change value. Method according to claim 3 or 4, characterized in that - an actual difference between a time (t ₅ ) at which said quotient (ΔI / Δt) reaches the second threshold (Q ₂ ) and an earlier time (t) is determined and compared with a desired difference of these times (t ₅ , t), - that depending on the target-actual comparison of the difference of this time (t ₅ , t) of the respective earlier time (t) for the next or another subsequent switching operation is adapted, in particular kept constant or shifted early or delayed, in particular by a predetermined change value. A method according to claim 5, characterized in that - the earlier time is a time (t ₃ ), starting from which at the respective catching coil ( 5 ) the catch current (I _catch ) is set, or - that the earlier time is a time (t ₂ ), starting from which at the respective catching coil ( 5 ) a Vorbestromung is performed. A method according to claim 6, characterized in that the Vorbestromung from the time (t ₂ ) for a predetermined period of time (t ₃ -t ₂ ) is performed and at the time (t ₃ ) ends, from which the catching current (I _catch ) at the respective catching coil ( 5 ) is set. Method according to one of claims 2 to 7, characterized in that the catching current (I _catch ) is greater than the Festzurrstrom (I _fixed ). Method according to one of claims 2 to 8, characterized in that the Festzurrstrom (I _fixed ) is adjusted until a predetermined period of time (t ₆ -t ₅ ) is reached, at the end of this period (t ₆ -t ₅ ) from the time (t ₆ ) a holding current (I _stop ) at the respective catching coil ( 5 ) is set. Method according to one of claims 1 to 9, characterized in that the catching current (I _catch ) is selected so that the present at the time (t ₅ ) minimum current (I _Min ) is likely to be greater than the holding current (I _stop ). Electromagnetic actuator, in particular for actuating a switching valve ( 11 ), with one between two end positions ( I . II ) and with a reset device ( 3 ) into one between the end positions ( I . II ) lying rest position ( III ) prestressed anchors ( 2 ) and at least one electromagnetic coil ( 5 ) for holding the anchor ( 2 ) at one of the respective end positions ( I . II ) associated stop ( 4 ) and with a controller ( 10 ) for carrying out the method according to one of claims 1 to 10.