EP0867898B1 - Electromagnetic positioning device - Google Patents

Abstract

The electromagnetic setting device has a pair of relatively spaced magnetic systems , each having an energising coil (3, 23) for displacement of a magnetic armature (17) between 2 switch positions. The magnetic armature is acted on by 2 opposing springs (11, 21), the energising coils connected in series or parallel, with a single magnetic system associated with a permanent magnet (71).

Description

The invention relates to an electromagnetically operating point device the specified in the preamble of claim 1 Art. Such an electromagnetic actuator is known from DE-C-0 912 721.

Another electromagnetic actuator is from Patent Abstracts of Japan: vol 11, No. 140, (M-586) JP-A61278673 known. A control circuit is described there with excitation coils connected in series or parallel to each other, the current through the excitation coils following a following first value switched to a lower second value becomes. The problem with this control device is the multitude of necessary circuit components and the complicated control of these circuit components. So are among other things 2 switching transistors in the circuit arrangement necessary, the mutually switched on by the control circuit Need to become.

Other electromagnetic actuators are known from EP-A-0 405 191 and EP-A-0 405 187.

Another electromagnetic actuating device is described in DE 39 28 066 A1. The actuator is for electromagnetic control of the gas exchange valve one Reciprocating internal combustion engine provided. The actuator has two mutually objectionable magnet systems, between which an anchor plate with an actuator stem to which the valve plate of the valve is coupled, can be moved back and forth. The valve-side magnet system for opening the valve exists from a known electromagnet with excitation coil, while the magnetic system facing away from the valve for closing of the valve has a permanent magnet whose magnetic field can be neutralized by a compensation coil.

Another electromagnetic actuator is described for example in DE 35 00 530 A1. To control a Valve of an internal combustion engine is instead of that mechanical cam control an electromagnetically working Control suggested. This consists of two magnet systems each with an excitation coil and an associated permanent magnet. Both systems, i.e. Permanent electromagnets act on a common anchor plate between them, which is firmly connected to a valve stem. On the anchor plate and thus push the valve in the opposite direction two feathers. The permanent magnets keep the armature in the end positions. The holding force of the permanent magnets becomes a trigger the valve movement by energizing the associated electromagnetic System lifted so that the anchor and therefore the valve under the action of the other magnet is transferred to the other end position.

The holding force of the two permanent magnets can be determined by a, the magnetic field of the permanent magnet opposite Cancel the DC field of the associated electromagnet. Will the Excitation coil of the permanent electromagnet in question is supplied with a current of suitable polarity and strength the permanent magnet "neutralizes". The result is that the anchor falls under the action of the preloaded spring and from which other permanent electromagnet is captured. Whose Permanent magnet in turn holds the armature in its stroke end position until its holding force through the constant field of this permanent magnet assigned permanent magnets assigned electromagnetic system will be annulled. The advantage of this solution is that only a short alternating energization of the electromagnetic Systems is necessary. Another advantage is there in the fact that this control device is relatively short Valve closing and opening times are available. About that In addition, the permanent magnets ensure that the control valve in the Normally with the engine switched off and thus with the engine switched off Power supply remains in the desired stroke end position.

However, in order to obtain the short operating times required a relatively complicated act on the two Excitation coils with suitable control signals required. Around to ensure proper operation of the actuating device, must a control circuit each of the two excitation coils Provide suitable control signals separately. The control circuit must ensure that no overlapping of the switch-on times accidentally occurs. In addition, the on and off times of the control signals for the two excitation coils exactly in time be coordinated.

Similar actuators are also in DE 30 24 109 A1 and DE 33 07 683 C1 described. Both actuators have also two electromagnets, between which an anchor plate is movable back and forth. The anchor plate itself is firmly connected with an employment. In these two However, no magnetic system with permanent magnets is provided for documents.

All o.b. The common feature is that the two provided magnet systems to achieve short switching times controlled separately with appropriate control signals have to be what a significant circuit Effort in a control circuit causes, and that the anchor plate when the power supply is switched off or at a control error a regularly undesirable middle position occupies. This means that for a restart a additional device, similar to DE 30 24 109 A1 or DE 33 07 683 C1 described, is required to the anchor plate to get out of the unwanted middle position.

At the o.b. Adjustment devices is necessary due to the separate control of the existing in the two magnet systems Excitation or compensation coils absolutely necessary, that each of these coils with separate outputs of a suitable one Control circuit is connected. A parallel or Series connection of these coils is therefore excluded.

The present invention is based on the object Electromechanical actuator mentioned at the beginning so that on the one hand a considerably easier one Control of the excitation coils is possible, and on the other hand the actuator in the de-energized state always in a defined, predetermined end position is brought.

This task is electromagnetic in the aforementioned Actuating device working in the license plate of the specified features solved.

The invention therefore essentially consists in that both connected in series or parallel to each other unchanged Excitation coils from the control circuit to the mutual Moving the armature into the first and second switching positions On / off control signals are provided, the A control signal after a predetermined first value lower second value (holding excitation) can be reduced.

In contrast to the known electromagnetic working Actuators is in the actuator according to the invention always ensure that the anchor is in de-energized Condition of the excitation coils assumes a stable end position. As soon as the control circuit a control signal for energizing the Provides excitation coils, both excitation coils are due through their series or parallel connection of current. With sufficient current and correct polarity of the current the anchor is based on its rest position, in which he on the one provided with the permanent magnet Electromagnet is present on the opposite electromagnet drawn. This happens because the effect of the Permanent magnets on the one hand by energizing one Excitation coil neutralized and by the simultaneous Excitation of the other excitation coil one magnetic field in the other Electromagnet builds up. This latter magnetic field pulls the armature to the other electromagnet. Will then the current through the two excitation coils switched off, falls the anchor returns to its rest position.

The spring force of the springs and the magnetic force are preferred of the permanent magnet dimensioned so that the armature in de-energized state of the two excitation coils from the alone given by the springs stable spring position in the direction of the magnet system to which the permanent magnet is assigned, staggered.

The main advantage of the actuating device according to the invention is that both excitation coils are from one and the same Control signals of a control circuit can be applied, because that a very simple control circuit is sufficient. The control circuit can, for example, at its output terminals a pulse width modulated voltage signal for Provide the current with its duty cycle can be determined.

To large switching forces of the actuating device according to the invention to achieve, in a further development of the invention both magnet systems preferably with an overexcitation current switched (100% DE). This overexcitation current neutralizes the permanent magnet and gives the other magnet system large switching forces. After switching operation with overexcitation current is reduced to a lower current value, the so-called Holding current, reduced or switched back (lower % ED, lower power consumption, less warming). The holding current is dimensioned according to the invention so that the Desired holding force with zero air gap between permanent magnet and magnet system is ensured.

Figur 1

eine Schnittansicht durch ein erstes Ausführungsbeispiel einer elektromechanisch arbeitenden Stelleinrichtung nach der Erfindung,

Figur 2

eine stirnseitige Draufsicht auf die Stelleinrichtung von Figur 1,

Figur 3

zwei mögliche Blockschaltbilder mit einer an eine Steuereinrichtung geschalteten Stelleinrichtung gemäß Figur 1

The actuating device according to the invention is explained in more detail below using an exemplary embodiment in connection with figures. Show it:

Figure 1

2 shows a sectional view through a first exemplary embodiment of an electromechanically operating actuating device according to the invention,

Figure 2

3 shows an end view of the actuating device from FIG. 1,

Figure 3

two possible block diagrams with an actuating device connected to a control device according to FIG. 1

Designate in the following figures, unless otherwise indicated, same reference numerals, same parts with the same Importance.

In Figure 1 is a sectional view through an embodiment an electromagnetic actuator shown. The control device shown in sectional view has a tubular housing 1. Inside the case 1, a control shaft 15 is arranged centrally by two Plain bearings 19a, 19b is guided and with a still to be explained Compensating element 51 cooperates. The staff 15 extends through the entire axial length of the housing 1.

At about half the axial length of the housing 1 is a plate-shaped Anchor 17 attached to the stem 15. The anchor 17 is located between two magnet systems and thus in the magnetic Circle of both the left and right magnet systems arranged. Both magnetic systems are after Kind of pot magnets preferably rotationally symmetrical. The magnet system arranged on the left in FIG. 1 exists from a pot-shaped jacket 9, a core 5 and a coil former 7, on which an excitation coil 3 is wound. Between the bottom plate of the jacket 9 and the core 5 is a plate-shaped permanent magnet 71 arranged. The magnetization this permanent magnet 71 is chosen so that the north pole N and south pole S are provided as plate-shaped elements are, the plate levels parallel to the plane of the plate-shaped Permanent magnets 71 are arranged. The separation of The north pole N and south pole S are dashed in Figure 1 in the permanent magnet 71 indicated.

There is an opening in the bottom plate of the jacket 9, in which a bearing bush 19a sits. In this bearing bush 19a and in an opposite bearing bush 19b Position 15 led.

The permanent magnet 71 also has a central opening in which an annular element 13 sits. At this Element 13 is supported by a compression spring 11 with one end. This compression spring 11 is arranged coaxially around the control shaft 15. Around this compression spring 11 is the core 5 of the Magnet system. The compression spring 11 is supported with her other End at the plate-shaped anchor 17.

As the representation of Figure 1 shows, the plate-shaped Anchor 17 flat on the front side of the left magnet system air gap-free.

Within the housing 1 is another magnet system that only one electromagnet and no assigned permanent magnet has arranged. This electromagnet has one a coil carrier 27 wound excitation coil 23. The Magnetic system of this electromagnet is in this embodiment also designed rotationally symmetrical and has a one-piece magnetic body 25, which has a central through opening. Through this Through opening extends the stem 15. The Position shaft 15 is guided in the bearing bush 19b, which on the Bottom side of the magnetic body 25 is attached. In the centric Through opening of the magnetic body 25 is seated Compression spring 21, which is on the one hand on the plate-shaped armature 17th and on the other hand on a ring-shaped projecting shoulder supports in the vicinity of the bearing bush 19b. The left front this electromagnet is spaced from the opposite one Surface of the plate-shaped anchor 17.

The end of the actuator stem protruding from the bearing bush 19b 15 is connected to a compensating element 51. This Compensating element 51 serves to ensure that even at existing end stop of the part to be moved the anchor plate 17 air gap on the magnetic body 25 of the electromagnet is applied. This measure guarantees a low holding power. Furthermore, the prestressed compression spring 53 in End of stroke position almost constant forces. So that to be moved Part that is articulated in the bore 52, too can perform an arcuate movement is the compensating element 51 on the control shaft 15 via a compensating ring 59 gimbal mounted.

Such actuators are ideal where Large actuating forces in the stroke start or stroke end position with a small one Construction volume, small weight and small performance required e.g. for flap adjustments in automotive applications. Of this actuator is also suitable for actuation of elements that require a specific work profile.

According to the invention, the two excitation coils 3, 23 are either connected in series or parallel to each other. The row or Parallel connection of the two excitation coils 3, 23 is with output terminals 43, 44 of the control circuit 41 already mentioned in connection. In the position of the armature 17 shown the entire actuator is in a de-energized state. In this de-energized state, the in the left magnet system ensures existing permanent magnet 71 for the armature 17 lies flat against the magnetic body 5, 9 of the left magnet system.

Provides the control circuit 41 at its output terminals 43, 44 a current of suitable polarity at a sufficient level A magnetic field builds up in the left magnet system on, which cancels the magnetic effect of the permanent magnet 71. At the same time builds by energizing the excitation coil 23 in right electromagnet a magnetic field that the armature 17th attracts. The armature 17 therefore moves to the right electromagnet and strikes there on the left face of the magnetic body 25 on. If the energization of the two excitation coils 3, 23 ends, the anchor 17 falls back into the figure 1 position shown.

The main advantage of this control device is that very simple control option by switching on and off a control signal. A separate control of the two excitation coils 3, 23 is no longer necessary.

3 shows two different block diagrams, in which the one in connection with FIG explained two excitation coils 3, 23 one after the other (cf. Figure 3 above) and on the other hand connected in parallel are (see FIG. 3 below). These two connected in series or excitation coils 3, 23 connected in parallel with output terminals 43, 44 of a control circuit 41 in connection. This control circuit 41 is shown schematically and contains only one switching device between two Switching states S1, S2 is switchable. In the switch position S1 reaches the control circuit 41 on the input side applied voltage U to the output terminals 43, 44 while with switch position S2 the switch is open and consequently at the output terminals 43, 44 of the control circuit 41 there is no voltage signal. From the illustration in FIG. 3 it is clearly evident that in the switch position S1 is independent from the choice of a series or parallel connection of the Excitation coils 3, 23 flowed through by current at the same time become. A separate control of both excitation coils 3, 23 not necessary. For completeness are in Figure 3 shows the two connected to the output terminals 43, 44 Supply lines with the reference numbers 31, 32.

LIST OF REFERENCE NUMBERS

1

casing

3

excitation coil

5

core

7

coil carrier

9

metal part

11

compression spring

15

set shaft

17

anchor

19a

bearings

19b

bearings

21

compression spring

23

excitation coil

25

core

27

coil carrier

31

management

32

management

41

control circuit

43

output terminals

44

output terminals

51

compensation element

52

drilling

53

compression spring

59

compensation ring

71

permanent magnet

Claims (12)

1. Electromagnetically operating positioning device with two magnet systems spaced apart from one another and each having an excitation coil (3, 23), between which is arranged an armature (17), which is positively connected to a positioning shaft (15), is clamped between two springs (11, 21) acting in opposition and is movable by the magnet systems into two switching positions, a permanent magnet (71) being associated with just one of the two magnet systems and the two excitation coils (3, 23) being connected either in series or in parallel with one another, and it being possible for them to be connected to output terminals (43, 44) of a control circuit (41), characterised in that on/off control signals (S1, S2) are provided from the control circuit (41) to the two unchanged excitation coils (3, 23) connected in series or parallel with one another for the reciprocal movement of the armature (17) into the first and the second switching position, it being possible to reduce the on control signal (S1) after a given first value (over-excitation) to a lower second value (holding excitation).
2. Electromagnetically operating positioning device according to Claim 1, characterised in that the springs (11, 21) and the permanent magnet (71) are sized so that, in the de-energised state of the two excitation coils (3, 23), the armature (17) are [sic] offset from the stable spring position defined by the springs (11, 21) alone in the direction of that magnet system, with which the permanent magnet (17) is associated.
3. Electromagnetically operating positioning device according to Claim 1 or 2, characterised in that an on signal S1 can be controlled by a pulse width modulation.
4. Electromagnetically operating positioning device according to one of Claims 1 to 3, characterised in that the amplitude and polarity of the on control signals (S1) is chosen so that the holding effect of the permanent magnet (71) is just neutralised in the first electromagnet.
5. Electromagnetically operating positioning device according to one of Claims 1 to 4, characterised in that an on control signal (S1) can be made available by the control circuit (41), which, after a given first value (over-excitation) is reduced to a lower second value (holding excitation).
6. Electromagnetically operating positioning device according to one of Claims 1 to 5, characterised in that the armature (17) is designed in the form of a plate.
7. Electromagnetically operating positioning device according to one of Claims 1 to 6, characterised in that the two excitation coils (3, 23) are designed identically to one another.
8. Electromagnetically operating positioning device according to one of Claims 1 to 7, characterised in that the two excitation coils (3, 23) are designed differently.
9. Electromagnetically operating positioning device according to one of Claims 1 to 8, characterised in that the permanent magnet (71) lies parallel to the armature (17) but flat against the side of the first electromagnet, which faces away from the armature (17).
10. Electromagnetically operating positioning device according to one of Claims 1 to 9, characterised in that both poles (N, S) of the permanent magnet (71) are plate-shaped and arranged next to one another and parallel to the plane of the plate of the permanent magnet (71).
11. Electromagnetically operating positioning device according to one of Claims 1 to 10, characterised in that the positioning device is coupled to a part to be moved via a compensation element (51) and in that the compensation element (51) enables the armature (17) to lie against the core (25) of the magnet system without an air gap when an end stop exists for the part to be moved.
12. Electromagnetically operating positioning device according to one of Claims 1 to 11, characterised in that the compensation element (51) provides for an axial stroke compensation, an arc-shaped stroke compensation for rotary movement via an eccentric or a rotational stroke compensation after converting an axial movement into a rotary movement.

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