WO1998042959A1

WO1998042959A1 - Electromagnetic control device

Info

Publication number: WO1998042959A1
Application number: PCT/EP1998/001718
Authority: WO
Inventors: Heinz Karl Leiber
Original assignee: Lsp Innovative Automotive Systems Gmbh
Priority date: 1997-03-24
Filing date: 1998-03-24
Publication date: 1998-10-01
Also published as: EP0970296A1

Abstract

The invention relates to an electromagnetic control device comprising two multipolar, preferably bipolar electromagnets, which are provided in each case with a magnetic yoke (4) with magnetic yoke limbs (5) and at least one coil (8), together with an armature (1) moving back and forth between the pole surfaces (3a) of both electromagnets. Said armature is brought into end positions by alternate electromagnet switching, at least in the vicinity of the pole surfaces (3a) of the corresponding electromagnet. The armature (1) is connected to a part (40) which is to be driven. The outer magnetic yoke limbs (5) of at least one of the electromagnets move towards each other in the direction of the poles and/or said limbs (5) are tapered towards their ends.

Description

ELECTROMAGNETIC ACTUATOR

The invention relates to an electromagnetic actuating device with two multi-pole, preferably two-pole electromagnets, each having a magnetic yoke with magnetic legs and at least one coil, and with an armature that can be moved back and forth between the pole faces of the two electromagnets, which at least when the electromagnets are alternately switched on in end positions is brought near the pole faces of the corresponding electromagnet, the armature being connected to a part to be driven.

Electromagnetic actuators of this type can e.g. be used in internal combustion engines to control the Em- / Auslaßventιle required for a gas change. These devices are therefore suitable to replace the usual camshaft controls. These electromagnetic actuators can also be used to adjust other elements, where a short adjustment path of a few millimeters is sufficient. For example, the electromagnetic actuators can e.g. can also be used for pumps.

In order to transfer the movement of the armature to a valve of an engine, for example, the 7-armature usually has holes through which it is connected to a part to be driven. This part in turn transmits its movement directly or indirectly to the valve.

An actuator of the type mentioned is e.g. known from DE 19521078 AI. In this known device, the armature is cuboid and has a remanent induction to save energy. In addition, each of the electromagnets used here has a U-shaped yoke shape with pole faces lying parallel to one another, the pole cross section remaining constant with increasing distance from the armature. The U-shaped yoke shape also ensures that the magnetic yoke legs are parallel.

The invention has for its object to reduce the energy expenditure or the power consumption of the electromagnetic actuating device and the weight of the moving masses, whereby an overall optimization of the efficiency, in particular in the end positions of the armature is to be achieved.

A minimum weight of the moving masses is important here, since it is squared in the power consumption. In addition, these demands should be met at acceptable costs.

This object is achieved in that the outer magnet yoke legs of at least one electromagnet approach each other towards the poles and / or that the magnet leg taper towards the end.

Characterized in that the magnetic yoke legs approach each other in the direction of the poles, whereby the yoke pole distance is reduced, the outer dimensions of the armature and thus of a substantial part of the moving mass can be minimized, thus saving weight.

This weight saving manifests itself positively in the lower power required to control the electromagnetic actuating device, and in an increase in the possible switching cycles and shorter switching times.

In addition, this construction realizes a magnetic circuit in which the magnetic flux has a homogeneous, in particular curved, shape without corners, which likewise leads to lower losses.

Despite the small distance between the poles located at the ends of the magnetic yoke legs in the vicinity of the armature, this device has only slight stray field losses in comparison to the losses in the working air gap, since the distance of the approaching magnetic yoke legs increases with the distance from the armature the magnetic yoke leg increases and the scattering losses become smaller and smaller.

The small distance between the poles of the magnetic yoke legs is therefore only achieved in the immediate vicinity of the armature.

Additionally or alternatively, the magnetic yoke legs are designed such that they taper towards the end. Accordingly, the poles or pole areas, which are located at the ends of the legs, also have this tapering course. The tapering of the poles takes place here at a spread angle β which is between 5 and 90 °, preferably between 10 and 50 ° and in particular around 30 ° lies. The spread angle β is the angle at which the side surfaces of the poles or the ends of the magnet yoke are oriented to one another.

Since this results in smaller pole faces of the magnetic yoke, the associated pole faces of the armature can also be reduced. This in turn results in a reduction in the size of the armature, which results in a reduction in weight with the advantages already mentioned above.

The approach of the magnet yoke legs is preferably realized in that at least the ends of the outer magnet yoke legs are directed towards one another too obliquely inwards. In this case, the magnetic yoke legs run towards each other at an opening angle α. It is also possible that not only the ends, but the magnetic yoke legs are directed inwards over their entire length.

The opening angle α at which the magnetic yoke legs run to each other is between 10 ° and 170 °. At an angle of 170 °, the magnetic yoke legs run almost parallel to one another. Opening angles of α = 30-120 ° are usually selected. Angles from 45 ° to 90 ° are particularly preferred.

It is also possible that only one magnet yoke leg is directed towards the other magnet yoke leg while it is straight in the usual way.

In general, it should be noted that the course of the approaching magnetic yoke legs does not necessarily have to be in a straight line. An approximation is through almost any zygomatic course possible. The course of the legs, which can also be given in a curved shape, is often determined by installation criteria, such as the space available.

The adjusting device is advantageously characterized in that the pole faces of the magnetic yoke and armature are essentially parallel to one another, at least in the end positions of the armature. This construction enables an even and smallest possible air gap between the poles of the armature and the magnet yoke, in particular in connection with a one-sided mounting of the armature.

It is particularly advantageous in this construction that the magnetic yoke i.e. the main areas of the magnetic yoke and in particular the magnetic yoke legs have a larger cross section than the magnetic yoke poles, inter alia due to the tapering shape of the magnetic yoke legs.

With a constant magnetic flux, which is given in particular by the excitation current in the coil and by the choice of material of the magnetic yoke, a lower flux density results in the magnetic yoke than at the magnetic yoke legs or at their ends / poles. This results in low iron losses, which in turn improves the overall efficiency of the electro-magnetic actuating device. A further reduction in iron losses can be achieved in that both the magnetic yoke and the armature are made laminated. This lamination can effectively suppress eddy currents which would otherwise lead to losses.

It proves to be particularly advantageous if the poles, in particular the tapered poles, are placed on the ends of the magnet yoke legs and / or have a greater saturation induction than the other regions of the magnet yoke. Since a greater flux density is established in the tapered pole areas of the magnetic yoke legs than in the other areas of the magnetic yoke, it is important to be able to choose a different material for the poles of the magnetic yoke than for the other parts of the magnetic yoke. Due to the greater magnetic flux density, a material is chosen for the poles that has a greater saturation induction.

In a particularly preferred variant, the distance between the magnetic yoke poles is set to a minimum in accordance with the design of the magnet yoke legs tapering toward one another, since in this case the armature is further reduced and the weight of the moving mass can thus be saved.

It should be noted, however, that scattering losses can occur in the vicinity of the pole regions, which are reduced in the present invention in that the magnetic yoke legs move away from one another with increasing distance from the armature at the opening angle α already mentioned. To minimize the scattering losses, the average distance between the poles should be chosen larger than the sum of the air gaps.

Due to the small distance between the magnetic yoke poles and the tapering course of the poles, which results in a small Results in the pole face, the correspondingly reduced armature is located in an area of greatest magnetic flux density, so that a material that has a high saturation induction must also be selected for the armature. In particular, the saturation induction of the armature should be greater than that of the magnetic yoke or its main area. On the other hand, it can be comparable to the saturation induction of the poles placed on the magnetic yoke legs.

It is particularly advantageous if the pole faces of the magnetic yoke and armature are preferably inclined at an angle γ between 30 ° and 45 ° to the direction of movement of the armature. Other angles are also possible. This results in the possibility that the effective air gap L can be reduced for a given stroke H. With a reduction in the air gap, there is also an improvement in efficiency because of the lower magnetic voltage.

In a construction in which the pole faces of the magnetic yoke and armature are oriented to the direction of movement of the armature at the angle γ mentioned, the effective air gap L for a given stroke H is given by the relationship L = H x SIN (γ).

Compared to electromagnetic actuating devices in which the pole faces of the armature and magnet yoke are arranged perpendicular to the direction of movement of the armature and in which the maximum stroke is thus given by the width of the air gap, the device according to the invention can be used given the stroke H, the air gap L is significantly reduced, which results in lower electrical power consumption.

A particular variability of the device results from the fact that the individual pole faces are inclined differently to the direction of movement of the armature. With such a construction, different and asymmetrical anchor shapes can be realized. In particular, one can take into account the different requirements that arise for the two end positions of the anchor, these end positions e.g. correspond to the open or closed state of an Em / exhaust valve in an internal combustion engine. In particular, the pole face geometry of the two electromagnets can be different, i.e. Large, shape of the cross-sectional area and inclination can be individually adapted to different requirements.

Another advantage results from the fact that the armature-side pole faces are larger than the cross-sectional area in the center of the armature. As a result, a uniformly high flux density is achieved in the anchor material, in particular in the case of a material with a higher saturation reduction. The induction in the anchor can be close to or reach the saturation modulation.

In the advantageous configurations of the magnetic actuating device described so far, optimization has been achieved, for example, by poles placed on the magnetic yoke legs with increased satiety reduction. If costs for the special pole material are to be saved, the pole faces of the yoke and armature are made larger, whereby they are dimensioned in the end positions of the armature so that operation with acceptable induction and small iron losses is possible.

A tapering course of the magnetic yoke legs is then also possible and preferred.

In this case, and also when using a pole material with a higher saturation induction, an improvement in the efficiency of the electromagnetic actuating device is possible in that the moving armature has recesses. In particular, as mentioned above, the central cross-sectional area of the armature can be smaller than the pole area due to recesses, which results in the advantages mentioned. Corresponding to the recesses, there is a weight saving, which in turn is advantageously noticeable in the power consumption of the electromagnetic actuating device.

It has a particularly positive effect if the recesses are arranged in the region of the center of the armature. The recesses can be e.g. be arranged next to the bores, which serve to connect the moving armature to the part to be driven. In particular, this recess can correspond to a normal bore or be adapted to the cross-sectional shape of the armature.

In the case of an approximately central recess in the armature, the shape is to be chosen so that the magnetic flux flows uniformly around this recess in the armature. A most homogeneous, for example arc-shaped course of the magnetic flux without corners is thus guaranteed.

In addition, it is advisable to make the recesses on the Arrange the surface of the armature, especially between the pole faces.

Essentially, the magnetic flux is introduced into the armature through the pole faces. Anchor material that is located between the pole faces and is not penetrated by the magnetic flux is removed in accordance with this design feature in order to achieve a further weight reduction of the armature.

Here, the cross-sectional area of the armature following the pole face is to be designed in such a way that a uniform high flux density with small air gaps is achieved in the armature material, which is close to the saturation reduction.

Another advantageous embodiment results from the fact that the armature can contain a permanent magnet. This magnet applies a holding force in the end positions, which makes it possible to reduce the holding current through the coils of the magnet yoke in the end positions.

To actuate an element, for example an em / exhaust valve in an internal combustion engine, it is provided that the armature is connected to a lever which is rotatably mounted at one end. The movement of the armature between the two electromagnets can thus be implemented as a movement of the lever. If the armature is also on the side opposite the bearing of the lever, at the other end of the lever, a long lever path ensures that the almost parallel orientation of the pole faces is maintained when the armature moves. The lever is advantageously mounted on a torsion spring which at least partially generates the spring forces for the armature in order to hold it in the intermediate position when the electromagnet is switched off. The torsion spring can also be designed such that the spring forces are fully applied. Furthermore, it is possible to arrange additional springs, in particular helical springs, on the lever, which hold the armature in the intermediate position.

The adjusting device according to the invention is further characterized in that an actuating element, in particular a rod, is articulated between the armature and the bearing of the lever. By means of this rod, the armature movement between the two electromagnets can be converted into an up and down movement of the rod, whereby depending on the distance of the articulation point of the rod from the armature, a more or less strong reduction of the armature movement takes place. The rod, which is set in motion by the armature, can be used when the actuator for controlling intake / exhaust valves in internal combustion engines is used to transmit its motion directly or indirectly via an intermediate part to the stem of the valve to be actuated.

Since the distance between the armature and the bearing of the lever is greater than the distance between the articulation point of the rod and the bearing of the lever, a smaller force given by the lever ratios must be applied by the electromagnet compared to the force that actuates the valve, so that the magnet systems of the actuating device are overall smaller and thus lighter can .

By using this lever construction, weight can in turn be saved on the moving parts.

Preferred embodiments of the invention are shown in the following drawings. Show it:

1 and 2 actuating devices according to the invention with attached and tapered poles with high saturation induction and different anchor shapes,

3 and 4 adjusting devices according to the invention without attached poles with differently shaped anchors which have recesses,

Figure 5 The overall view of a

Actuating device with an armature mounted on a lever, the movement of which is converted into the movement of a valve,

Figure 6 The storage of the lever on a

Torsion spring,

Figure 7 An alternative embodiment in which the poles are perpendicular to the direction of movement of an armature with lateral recesses.

Figure 1 shows an anchor, which is essentially the shape two trapezoids lying on top of each other with their long base. The material of the anchor is of high quality, which means that it has a high saturation induction. The poles 2 of the armature are opposite yoke-side poles 3, which likewise consist of magnetically high-quality material and are placed on the ends of the yoke legs.

The magnetic yoke legs approach each other in the illustrated case in that they are directed obliquely toward one another at the opening angle α. It is not the legs as a whole, but only the end areas that face inwards. The opening angle is α = 45 ° and thus moves in the particularly preferred range from 45 ° to 90 °.

This also shows that the pole faces 3a of the magnetic yoke and the pole faces 2 of the armature, in particular in the end positions, not shown, are essentially parallel to one another.

It can also be seen that the poles 3 of the magnet yoke leg 5 taper towards the end of the magnet yoke leg, that is to say in the direction of the armature 1. The taper takes place at the spread angle β, which in the present case is 37 °. Other angles are also possible. The yoke 4 or the yoke 5 of the opposite electromagnet, which is no longer shown, has a cross section which is significantly larger than that of the poles and is made of a material which has less induction of saturation.

ExemDlarisch is only at yoke 4 of the upper electromagnet a winding 8 indicated. When the windings are activated, the armature 1 is moved in one of the directions of the double arrow 6 toward the poles 3 of the upper or lower electromagnet. The movement of the armature 1 is transmitted via a lever, not shown, which is fastened to the bores 7 of the armature, to other elements which are used, for example, to control a valve. The lever, not shown here, can for example be connected to a torsion bar bearing.

The orientation of the pole faces is chosen in the present case so that the faces are inclined at an angle γ to the direction of movement 6 of the armature. The angle γ is chosen to be 45 ° here. This ensures, as mentioned above, that a smaller air gap can be set between the poles for a given stroke. In the given case, the air gap L is only 70% of the stroke H. Again, other angles are possible.

A similar construction is also shown in FIG. 2. The exemplary embodiment in this figure differs from that in FIG. 1 essentially only in that the anchor 10 has the shape of two trapezoids with different angles of inclination of the non-parallel sides relative to one another. The angles of the pole faces to the direction of movement of the armature can be e.g. γ = 45 ° and below approx. 30 °.

The pole area is significantly larger here than in the exemplary embodiment according to FIG. 1. Due to the different orientation of the pole areas to the direction of movement of the armature, the different areas can be different Requirements when opening or closing a valve are taken into account. The lower and upper pole faces also have different sizes. In addition, the armature 10 has recesses 11a and 11b in the region of its center and at its lower end in order to save weight.

The shape of the recess 11a is adapted approximately to the outer cross section of the armature. Here too, bores 12 are provided on the armature, which are used to fasten the armature to a bearing, such as to serve as a lever. The holes are arranged in the present case so that they do not negatively affect the magnetic flux through the upper part of the armature. In the exemplary embodiments according to FIG. 1 and FIG. 2, a pole area is approximately as large as the central armature cross-sectional area in the direction AA (FIG. 1) or the sum of the armature cross-sectional areas (FIG. 2).

In the exemplary embodiments of FIGS. 3 and 4, the anchor 20 or 30 basically has a shape which corresponds to two trapezoids lying one on top of the other. However, the armature 20 and 30 and the pole 21 and 31 on the axis are not made of the high-quality material compared to FIGS. 1 and 2. Instead, the yoke and armature-side poles have larger pole faces. The magnetic yoke legs taper in the pole area, but this need not necessarily be the case. To reduce the weight, the anchors 20 and 30 are provided with recesses 22 and 32, respectively.

In the exemplary embodiment in FIG. 3, these recesses 22 are located between the pole faces at the top and bottom, without negatively influencing the magnetic flux through the armature. In the embodiment of Figure 4, the recess 32 is in turn in the area of the anchor center. The recesses in both the armature 20 and the armature 30 are designed such that the area of a pole AP is larger than the cross-sectional area of the armature in the center in the direction AA (FIG. 3) or as the sum of the cross-sectional areas of the armature on both sides of the recess 32. In addition to minimal weight, care was taken in the present exemplary embodiment in the dimensioning and geometry of the armature that the armature cross-section behind the larger pole faces was reduced in such a way that a uniform flux density was created in the armature material.

In the case of small working air gaps, there is therefore a high flux density, which requires an anchor material with a high degree of saturation.

As with the exemplary embodiment in FIG. 3, the solution according to FIG. 4 has the advantage that the magnetic flux is not inhibited by the fastening bores. From the figure 3 it can also be seen from the indicated field line F that the magnetic flux runs optimally in an arc shape between the two magnetic poles 21 through the armature 20. The oval shape of the recess 32 according to FIG. 4 also supports a uniform flow around the recess by the magnetic flux.

5 shows an overall overview of the electromagnetic actuating device in which the armature 30 is connected to a lever 40 which is rotatably mounted at the point 41. The armature is actuated by two helical springs 42 and 43 without actuation of one of the electromagnets in the intermediate position shown held. Approximately in the middle between .Anchor 30 and lever bearing 41, a rod is articulated as an actuating element 44, which in turn is connected to a valve stem 45 of an intake / exhaust valve of an internal combustion engine.

FIG. 5 also shows two excitation coils, each of which is wound around a yoke leg of an electromagnet. When the electromagnets are actuated, the armature 30 is moved from its intermediate position either upwards or downwards in accordance with the construction shown, this movement being reduced into a movement of the actuating element 44 by the lever ratios selected between the armature position and the articulation point of the element 44. The armature 30 thus carries out a larger stroke between the poles of the electromagnets than the correspondingly moved valve. Accordingly, the Kraftaufwanα in the electromagnet for actuating the valve is significantly reduced, so that a smaller and lighter actuator can be used.

FIG. 6 shows the lever 40, which is connected to a torsion bar or a torsion spring 46, which in turn is arranged perpendicular to the lever 40 and is clamped in a rotationally fixed manner at its other end. This torsion bar 46 or the torsion spring can at least partially generate the spring forces with which the armature is held in its intermediate position. The torsion bar is preferably additionally held in a support bearing (not shown).

FIG. 7 also shows a two-pole magnet system, the magnet yokes 51 and 52 of which run obliquely to an armature 50 mm. This in turn ensures that the Anchor length can be minimized. In this case, however, care must be taken to ensure that the leakage flux between the poles due to the smaller distance between the magnetic yoke poles remains acceptable.

In the present case, the pole faces of both the magnetic yoke and the armature are oriented perpendicular to the direction of movement of the armature 50. The stroke of the armature is therefore limited by the width of the air gap. In order to save weight and thus optimize efficiency, the flake anchor 50 has V-shaped recesses 54 on the outside of its edge. The tip of these recesses 54 can extend almost to the inner edge 53 of the yoke poles 51 and 52. This ensures that the magnetic flux also runs homogeneously and in an arc shape between the poles of the yokes through the armature in this exemplary embodiment. In the present exemplary embodiment, the yoke legs taper towards one another. However, this is not absolutely necessary.

FIG. 8 shows further possible magnetic yoke shapes 60 and 61, in which the magnetic yoke legs 62, 63, 64 and 65 of the electromagnets approach each other towards the poles and at the same time taper to the end.

The upper magnetic yoke 60 has a shape in which the left magnetic yoke leg 62 bends almost at right angles to the other leg 63 at approximately half its length.

The right leg 63 initially has an outwardly curved course in order to maintain the greatest possible average distance from the left leg 62, the End region of the leg 63 is bent in the direction of the left leg 62 and approaches it.

The lower magnetic yoke 61 has a shape in which the right magnetic yoke leg 64 runs straight and only the left leg 65 is directed towards the other leg. An armature 66, which is fastened to a lever (not shown) and is used for this purpose, in turn, moves between the poles of the magnetic yokes 60 and 61, e.g. to actuate a valve of an internal combustion engine.

Claims

claims

1. Electromagnetic adjusting device with two multi-pole, preferably two-pole electromagnets, each having a magnetic yoke (4) with magnetic yoke legs (5) and at least one coil (8) and with an armature (1 that can be moved back and forth between the pole faces (3a) of both electromagnets ) which, when the electromagnets are switched on alternately, is brought into end positions at least in the vicinity of the pole faces (3a) of the corresponding electromagnet, the armature (1) being connected to a part (40) to be driven, characterized in that the outer magnet yoke legs (5 ) at least one electromagnet approach each other towards the poles and / or that the magnetic yoke legs (5) taper towards the end.

2. Adjusting device according to claim 1, characterized in that at least the ends of the outer magnet yoke leg (5) at least one of the electromagnets are directed towards each other too obliquely inwards.

3. Adjusting device according to claim 1, characterized in that a magnetic yoke leg is directed towards the other magnetic yoke leg.

4. Adjusting device according to one of the preceding claims, characterized in that the pole faces

(2,3a) of the magnetic yoke (4) and armature (1) are essentially parallel to one another at least in the end positions.

5. Adjusting device according to one of the preceding claims, characterized in that the magnetic yoke (4), in particular the magnetic yoke legs have a larger cross section than the magnetic yoke poles (3).

6. Adjusting device according to one of the preceding claims, characterized in that the poles (3), in particular the tapering poles (3), are placed on the ends of the magnet yoke legs (5).

7. Adjusting device according to one of the preceding claims, characterized in that the magnetic yoke poles have a greater saturation than the main parts of the magnetic yoke (4).

8. Adjusting device according to one of the preceding claims, characterized in that the distance between the magnetic yoke poles is minimal.

9. Adjusting device according to one of the preceding claims, characterized in that the armature (1) has a higher saturation than the main parts of the magnet yoke (4).

10. Adjusting device according to one of the preceding claims, characterized in that the pole faces

(2,3a) of magnetic yoke (4) and armature (1), preferably inclined at an angle (γ) between 30 ° and 45 ° to the direction of movement of the armature (1).

11. Adjusting device according to claim 10, characterized in that the individual pole faces (2,3a) to the direction of movement of the armature (1) are inclined differently.

12. Adjusting device according to one of the preceding claims, characterized in that the armature-side pole faces (2) are larger than the cross-sectional area in the center of the armature.

13. Adjusting device according to one of the preceding claims, characterized in that the anchor

(1,10,20,30,50) recesses (11a, 11b, 22, 32, 54).

14. Adjusting device according to claim 13, characterized in that the recesses (11a, 32) are arranged in the region of the center of the armature.

15. Adjusting device according to claim 13, characterized in that the recesses (11b, 22, 54) on the surface of the armature, in particular between the pole faces (2) are arranged.

16. Adjusting device according to one of the preceding claims, characterized in that the armature contains a permanent magnet.

17. Adjusting device according to one of the preceding Anspr che, characterized in that the armature is connected to a lever (40,44) which is rotatably mounted at one end.

18. Adjusting device according to claim 17, characterized in that the lever is mounted on a torsion spring (46) which at least partially generates the spring forces for the armature.

19. Adjusting device according to one of claims 17 or 18, characterized in that springs (42), in particular helical springs, are arranged on the lever (40).

20. Adjusting device according to one of claims 17, 18 or 19, characterized in that an actuating element (44), in particular a rod, is articulated between the armature and the bearing of the lever.

21. Actuating device according to one of the preceding claims, characterized in that it is used to control intake / exhaust valves in internal combustion engines.