EP0644561B1 - Direct current electromagnetic actuator - Google Patents

Description

The invention relates to a DC solenoid according to the features of the preamble of claim 1.

Such a DC solenoid is known for example from DE 36 05 216 A1 or DE-PS 976 704. There, an electromagnet is described which has a cylindrical armature which can be moved along an axis, an excitation coil which is arranged coaxially with this armature and a magnetic iron system for guiding the magnetic field. The magnetic iron system consists of a hollow cylindrical pipe guide arranged coaxially to the axis of the armature and an armature counterpart at a distance from the pipe guide. The armature counterpart is provided with an end wall opposite the armature and with hollow cylindrical walls pointing in the direction of the armature and also arranged coaxially to the axis. The hollow cylindrical tube guide and the hollow cylindrical walls of the armature counterpart are arranged between the excitation coil and the armature. In addition, the anchor counterpart and the pipe guide is connected to one another via a housing arranged around the excitation coil for closing the magnetic circuit. When the excitation coil is energized, a magnetic field line course is generated in the magnetic iron system, as a result of which the piston-shaped armature can be moved linearly along the axis in the direction of the armature end face.

Such magnetic iron systems are also referred to as so-called lifting or pulling magnets. To adapt the lifting force characteristic, it is proposed in DE-PS 976 704 to design the hollow cylindrical walls on the armature counterpart as control cone walls in order to influence the course of the lifting force curve with ferromagnetic means and to have a low magnetic resistance from the housing of the magnetic iron system during the transition to the movable armature and one to achieve high flux density in the "magnetic working space". In the following, the term "magnetic working space" refers to the space that lies within the boundaries of the armature end face, the end face of the armature counterpart and the control cone walls.

In the known DC solenoids, however, it is still problematic to enable good efficiency in both surge operation and continuous operation.

How electromagnets can be calculated and designed using a computer program is e.g. B. in Philips techn. Rdsch. 1980/81, Vol. 39, No. 2, pages 52-61.

It is generally known in magnetic lifting devices (linear lifting magnets, rotary magnets, magnetically actuated clutches and brakes) due to a briefly greatly increased current surge (compared to the electrical power load) with continuous activation) to increase the action force of the magnet system considerably in order to make the switching process more precise and to shorten the switching accuracy over time.

The impulse control can be controlled, for example, by a switch attached to the end of the stroke, mechanically controlled by the stroke or by a secondary winding of a few turns, an induced control voltage being output for a relay as long as a change in the Manget field takes place during the switching process.

Electronic control is also possible, a magnetic sensor being able to react function-dependently from the magnetic field of the excitation winding, as well as via an electronically predetermined switching duration of the current surge, which measures the increased lifting power of the magnet system over time as required. The usual impulse times are between 0.1 and 0.2 seconds.

Such short-term overexcitation of the magnet system is used in commercially available electromagnets depending on the task. With the dimensions of the magnet system that have been customary up to now, the brief current surge can only bring about a narrowly limited increase in the power of the lifting work, since the magnetic system quickly becomes over-saturated and the conversion of the electrical power output can only be transformed into mechanical lifting work with a poor efficiency.

Another problem with the known DC solenoids is that during surge operation, the armature of the lifting magnet is magnetically held in its stroke end position after the surge excitation with the shock excitation force must, the excessive adhesive force at low power (corresponding to the continuous operating power) must be applied. These are two opposite technical requirements in solenoid construction.

Furthermore, EP 0 296 983 A1 discloses a double air gap lifting magnet which has an inner annular and an outer annular air gap. It is of crucial importance in this known solenoid that an armature connected to a piston rod is reduced in mass in order to thereby save weight and thus enable the armature to be moved back and forth more quickly. In this known lifting magnet, the magnetic iron system is narrowed at the parts deflecting the magnetic field lines.

Further lifting magnets are described in documents EP 0 380 693 A1 and GB-A-2 040 585. A special configuration of the magnetic iron system depending on the cross section of the armature plays no role in these lifting magnets.

The invention is therefore based on the object of providing a direct current lifting magnet which has improved efficiency both in the case of surge operation and continuous operation.

This object is solved by the features of claim 1.

$$\text{Q3 = (1,3 - 2.5) x Q2}$$

$$\text{Q5 = (2,2 - 4,4) x Q2}$$

$$\text{Q6 = (1,1 - 2,0) x Q1}$$

und $$\text{Q10 = (3,0 - 5,0) x Q2.}$$

The invention is essentially based on the fact that the magnetic iron system with pipe guide, armature counterpart and housing has a cross section which is enlarged in comparison to the armature cross section at its points deflecting the magnetic field lines, at which a deflection angle of the magnetic field line course changes or sets. The magnetic flux density at these deflecting points can thus be reduced, the cross-sectional areas of the magnetic iron system preferably being approximately as follows: $$\text{Q2 = (1.2 - 1.8) x Q1}$$

$$\text{Q3 = (1.3 - 2.5) x Q2}$$

$$\text{Q5 = (2.2 - 4.4) x Q2}$$

$$\text{Q6 = (1.1 - 2.0) x Q1}$$

and $$\text{Q10 = (3.0 - 5.0) x Q2.}$$

Q1 denotes the cross-sectional area of the armature, Q2 a cross-sectional area of the armature counterpart in a base region of the control cone walls, Q3 an area in the region of a first deflection of the magnetic field between armature counterpart and housing wall of the magnetic iron system, Q5 a transition surface in the region of a second deflection between an outer tube-like wall of the housing of the magnetic iron system and a cover-like element assigned to the armature counterpart Wall of the housing, Q6 a cross-sectional area of the outside housing wall and Q10 a cylindrical transition surface between the pipe guide and anchor.

If the aforementioned conditions are met, the magnetic field lines in the highly permeable iron system with a reduced flux density (compared to the flux density when running straight ahead) can perform a directional component of the iron molecules at the deflecting points with less effort in order to bring about the desired change in the overall direction of the field. The deflection power loss for the four-fold change of direction of the magnetic field around the excitation coil required in conventional solenoids can be kept extremely low in such an implementation.

In a further development of the invention, it is provided that the magnetic iron system together with the excitation coil is constructed at least approximately symmetrically to a magnetic energy symmetry plane running parallel to the cross section of the armature and that the end face of the armature in an initial stroke position lies at least approximately on this symmetry plane. Proceeding from this, the armature can be moved into a stroke end position up to the end wall of the armature counterpart. The cone tip of the cylindrical control cone is also at least approximately abutting the plane of symmetry. In the stroke end position, which is also referred to as the armature field closing position, the "magnetic working space" is completely filled by the armature. In the event that the surface of the armature opposite the armature end face is flush with the outer end of the magnetic iron system in the stroke position, the electromagnet is completely symmetrical to the plane of symmetry of the magnetic iron system. The energy content of the two halves of the magnet system on both sides of the plane of symmetry is thus equal in terms of magnetic energy content compared to the cylindrical "magnetic work space". Since the "magnetic working space" in the magnet system according to the invention is acted upon from both sides by straight field lines, an optimal control effect is achieved for the lifting force characteristic adaptation described in DE-PS 976 704. In addition, the "cone control" known from DE-PS 976 704 lies geometrically in the magnetically inductive, highly effective, centrally arranged interior of the excitation coil.

In a further development of the invention, the outer corners of the magnet system are provided with bulges to increase the radius of the curve, a gradual transition of the cross section before or after the curve to the straight-line part of the magnet system being advantageous.

Since the armature is exposed to high magnetic stress in its front part facing the armature counterpart when advancing into the "magnetic working space", it is expedient to manufacture the armature in its front part from a high-quality permeable magnetic material. In the rear part, however, the anchor can consist of a magnetic soft iron material. Otherwise it is possible to build the anchor from a highly permeable material.

The surface of the armature opposite the armature face is expediently connected to a short-circuit plate. This is to ensure that in the stroke end position and thus the field closing position, this short-circuit plate is magnetically short-circuited by placing it on the outer wall of the magnetic iron system between the armature and the pipe guide. To increase this effect and thus to increase the holding force of the armature in its stroke end position, an annular recess can be provided on the outer wall of the magnetic iron system between the pipe guide and the housing.

Due to the design of the hollow cylindrical control cone walls with a conical outer surface, the control of the lifting force characteristic curve can be represented for the design of both the impulse-operated magnet system and for the direct network operating method.

In order to achieve the best possible adjustment of the lifting force characteristic, the cylindrical cone with its conical outer surface is designed to be interchangeable. With the interchangeability of this control cone, the course of the traction curve can be influenced.

In order to achieve a favorable magnetic field course within the magnetic iron system, it is formed from two parts which are to be connected to one another on the plane of symmetry. Ie that corresponding housing parts are integrally formed on the anchor counterpart on the one hand and on the pipe guide on the other hand, and these two parts on the plane of symmetry can be connected to one another without any air gaps.

In order to make the magnet system according to the invention pressure-tight, an annular intermediate element made of non-magnetic material is to be arranged in a sealing manner between the opposite and spaced ends of the control cone walls and the pipe guide.

Due to its extremely reduced shape of the magnet system, the DC solenoid according to the invention enables small magnets to be built which can be kept very small in size.

The DC solenoid according to the invention takes advantage of the conditions necessary for effective miniaturization of solenoids. Highly permeable iron grades must be used as the material, the magnetization curves of which meet special conditions for switching the magnetic iron system on and off. In addition, these materials should be easy to machine for production and largely independent of temperature. This is possible by reducing the DC solenoid according to the invention and the magnetic iron system contained therein to extremely simple geometric shapes. In addition, it is possible to design the working air gap which is always required in such a way that the least possible scatter of the magnetic field occurs, particularly in the starting position of the stroke. Furthermore, the DC solenoid according to the invention makes good use of the fact that the "generator lifting force characteristic" can be adapted to a "consumer lifting force characteristic".

The main advantages of the DC solenoid according to the invention are essentially in the extremely simple structure, which enables miniaturization of the DC solenoid. In addition, the DC solenoid according to the invention is characterized by low stray field and therefore low losses.

As an alternative to this or in addition to this, the magnetic iron system together with the excitation coil can also be formed at least approximately symmetrically with respect to a plane of symmetry running parallel to the cross section of the armature, an end face of the armature in a start of stroke position being arranged at least approximately on this symmetry plane and starting therefrom up to the end wall of the armature counterpart is movable into a stroke end position. If the anchor counterpart is provided with a control cone, as is known per se from DE-PS 976 704, then the cone end of the control cone is expediently to be arranged at least approximately abutting the plane of symmetry.

As already mentioned, the walls of the anchor counterpart can be provided with a control cone. The wall end of the opposite armature is expediently also provided with a control cone and thus a bevel such that the wall ends of the armature and armature counterpart run parallel to one another. The resulting conical shape of the working air gap is particularly suitable for longer lifting heights of the armature. It has been found that the overlapping arrangement of the wall ends of the armature counterpart and armature in the form of bevelled ends results in little magnetic scatter.

However, such a conical shape of the working air gap is not mandatory. Rather, the wall ends of the armature and armature counterpart can also be made orthogonal to the axis of the DC solenoid. In addition, it is also possible to form the wall ends in a stepped manner, so that ferromagnetic contact similar to that of the cone control takes place already in the start of stroke position. The magnetic lifting force characteristic curve can thus be advantageously adapted to the demand characteristic curve with a corresponding excess force.

For the sake of simplicity, the housing of the direct current lifting magnet according to the invention merely consists of a non-magnetic pipe guide, in the ends of which the bottom-like walls of the armature and armature counterpart sit and are flush with the pipe ends of the pipe guide. For this purpose, the non-magnetic pipe guide has an inner cylindrical wall, on the one hand the anchor counterpart is arranged in a fixed manner and on the other hand the anchor is slidably seated. The inner wall of the pipe guide can be used here advantageously as a slideway. The pipe routing can their outer circumference be cylindrical or cuboid. It is only essential that the pipe guide is non-magnetic in order to avoid a magnetic short circuit in the working air gap.

Figur 1

eine ringförmige Spule mit kreisförmigem Spulenquerschnitt und den dazugehörenden Magnetfeldlinien,

Figur 2

eine Darstellung ähnlich zu Figur 1 mit einem zusätzlichen, dem Magnetfeldlinienverlauf angepaßten Magneteisensystem sowie einem in einer Öffnung des Magneteisensystems bewegbaren Anker,

Figur 3

ein erfindungsgemäßes Magnetsystem mit einer Erregerspule mit quadratischem Spulenquerschnitt, einem daran angepaßten Magneteisensystem sowie einem Anker,

Figur 4

ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Magnetsystems,

Figur 5

Zugkraftkurven eines bekannten Hubmagneten bei Dauerbetrieb (100 % ED) und Kurzzeitbetrieb (5 % ED),

Figur 6

Zugkraftkurven des erfindungsgemäßen Magnetsystems bei Dauerbetrieb (100 % ED) und Kurzzeitbetrieb (5 % ED), und zwar bei gleichem elektrischem Leistungsaufwand wie in Figur 5 und denselben Außenabmessungen,

Figur 7

ein Beispiel der Querschnittsflächen des in Figur 4 gezeigten erfindungsgemäßen Magnetsystems im Vergleich zu den Querschnittsflächen eines herkömmlichen Hubmagneten,

Figur 8

ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Magnetsystems mit Ausbuchtungen an den äußeren Rändern des Hubmagneten,

Figur 9

eine Darstellung ähnlich zu Figur 4, wobei zusätzlich das außenseitige Ende des Ankers mit einer Kurzschlußplatte versehen und an der außenseitigen Wandung des Magneteisensystems zwischen Rohrführung und Anker eine ringförmige Ausnehmung angeordnet ist,

Figur 10

eine Darstellung ähnlich zu Figur 4, wobei das Magneteisensystem eine Außenrundform aufweist,

Figur 11

ein weiteres erfindungsgemäßes Magnetsystem mit einem ein Hydraulikventil steuernden, druckdichten Innenrohr, wobei das Magneteisensystem ebenfalls eine Außenrundform aufweist, und

Figur 12, Figur 13

das in Figur 11 dargestellte Magnetsystem in auseinandergebautem Zustand.

The present invention is explained in more detail in the present on the basis of exemplary embodiments or curves shown in the figures. Show it :

Figure 1

an annular coil with a circular coil cross section and the associated magnetic field lines,

Figure 2

1 shows an illustration similar to FIG. 1 with an additional magnetic iron system which is adapted to the course of the magnetic field and an armature which can be moved in an opening in the magnetic iron system,

Figure 3

a magnet system according to the invention with an excitation coil with a square coil cross-section, a magnet iron system adapted to it and an armature,

Figure 4

another embodiment of a magnet system according to the invention,

Figure 5

Traction force curves of a known solenoid in continuous operation (100% ED) and short-time operation (5% ED),

Figure 6

Traction force curves of the magnet system according to the invention in continuous operation (100% ED) and short-time operation (5% ED), with the same electrical Performance as in Figure 5 and the same external dimensions,

Figure 7

4 shows an example of the cross-sectional areas of the magnet system according to the invention shown in FIG. 4 in comparison to the cross-sectional areas of a conventional lifting magnet,

Figure 8

another embodiment of a magnet system according to the invention with bulges on the outer edges of the lifting magnet,

Figure 9

4 shows a representation similar to FIG. 4, the additional end of the armature being provided with a short-circuit plate and an annular recess being arranged on the outer wall of the magnetic iron system between the pipe guide and the armature,

Figure 10

a representation similar to Figure 4, wherein the magnetic iron system has an outer circular shape,

Figure 11

another magnet system according to the invention with a pressure-tight inner tube controlling a hydraulic valve, the magnet iron system likewise having an outer circular shape, and

Figure 12, Figure 13

the magnet system shown in Figure 11 in disassembled state.

FIG. 1 shows an annular coil 1 of a magnet system with a circular coil cross section. If current flows through this ring-shaped coil 1, the magnetic field lines 2 shown in FIG. 1 result. The highest magnetic flux density occurs in the coil center due to the action of the current-carrying ring-shaped coil as a function of the distance from the coil center.

It is noteworthy in this embodiment that the annular coil 1 and the magnetic field lines 2 are arranged symmetrically to a plane of symmetry S. In addition, it can be clearly seen that the change in direction in the field line image is approximately uniform (similarly circular) and that there are no sharp corners or bends. The deflection angle of the magnetic field lines 2 is therefore almost always the same.

When the same ring-shaped coil 1, which is also referred to as excitation coil, is assembled with a magnetic iron system 3, as shown in FIG. 2, an almost constant "turning angle" of the magnetic field lines also arises. The magnetic iron system 3 is arranged in FIG. 2 in a rotationally symmetrical manner about the excitation coil 1 with respect to the coil axis A and points at its outer Edge a round cross-section. The rounding is correspondingly formed on the course of the magnetic field lines 2 shown in FIG. 1.

In addition, an armature 5 is shown in Figure 2, which is arranged linearly movable along the coil axis A. For this purpose, the magnetic iron system 3 is provided with an opening for the armature 5. In addition, this armature 5 is connected to a piston rod 4, which is arranged lying on the coil axis A at an opening of the magnet system 3 opposite the aforementioned opening for the armature 5.

The magnetic iron system 3 together with the coil 1 - with the exception of the openings for the armature 5 and the piston rod 4 - is constructed symmetrically to the plane S.

In the representation of Figure 2, the armature 5 is currently in its initial stroke position. If, on the other hand, current flows through the excitation coil 1, the armature 5 together with the piston rod 4 moves to the left in the illustration in FIG. 2, to the extent that it abuts the inner end wall 6 of the magnetic iron system 3. This space is referred to below as "magnetic displacement". This magnetic displacement (comparable to a cylindrical combustion chamber in an internal combustion engine) is consequently defined in the start of stroke position by the inner end wall 6 of the magnet iron system 3, the end face 8 of the armature 5 and the inner cylinder wall 7 of the magnet iron system 3.

As can be seen in FIG. 2, the end face 8 of the armature 5 is again at least approximately at the plane of symmetry S in the starting position of the armature 5. The magnetic iron system 3 in the representation of FIG. 2 is formed in two parts, as shown by the dashed lines in the lower half of the magnetic iron system 3. It goes without saying that it can also be composed of several parts. It is only essential that the magnetic iron system 3 has a pipe guide for the armature 5 and an armature counterpart with an end wall 6 opposite the armature, and walls are also provided which point in the direction of the armature 5 and also lie coaxially to the axis A. The two housing halves are aligned coaxially by fits on the outer diameter of the housing.

A special feature of the lifting magnet shown in FIG. 2 is that the magnetic iron system 3 is arranged directly around the excitation coil 1 except for the opening for the armature 5. This results in a control cone wall 10 at the edge region of the magnetic displacement 13 in the magnetic iron system 3, as is required from DE-PS 976 704 for adapting the lifting force characteristic of an electric lifting magnet. FIG. 2 also shows a magnetically favorable transition surface 11 between linearly movable armature 5 and magnetic iron system 3.

During the switching process, current flows through the coil 1 and the linearly movable armature 5 with the piston rod 4 is guided in the opening of the magnetic iron system 3 such that it can completely fill the magnetic displacement 13 during the switching process.

In the initial stroke position, as shown in FIG. 2 (ie the end face 8 of the armature 5 lies at least approximately on the plane of symmetry S), the magnetic displacement has the lowest magnetic energy content. In the field closing position, on the other hand, the anchor 5 has a high iron permeability bump against the end wall of the armature counterpart of the magnetic iron system 3 at the end of its working stroke. If the armature 5 is exactly as long as the opening of the magnet iron system 3, the surface opposite the end face 8 of the armature 5 is flush with the outer surface of the magnet iron system 3. This ensures complete symmetry of the magnet system with respect to the plane of symmetry S. If the armature 5 is in its stroke end position, the energy content of the two halves of the magnetic iron system 3 on both sides of the plane of symmetry S is equal in terms of energy content compared to the cylindrically shaped magnetic displacement 13.

In addition, the magnetic displacement 13 is acted upon from both sides by straight magnetic field lines. This measure achieves an optimal adaptation of the lifting force characteristic, since the control cone wall 10 lies geometrically in the centrally arranged interior of the excitation coil 1.

Although the magnet system shown in FIG. 2 has an almost circular magnetic field profile even with high magnetic excitation and can be regarded as extremely low in scatter, such a magnet iron system 3 with a rounded outer shape can only be produced with great technical effort. FIG. 3 therefore shows a magnet system according to the invention that is easier to manufacture and that has an excitation coil 1 with an approximately square coil window cross section. In this coil form, the magnetic field lines 2 no longer run in a circle, but approximately along a rectangle with four deflection points in the magnetic iron system 3. At these deflection points, the magnetic field line profile has a comparison with the other sections of the magnetic field line profile changed, ie larger deflection angle. According to the magnetic field theory, a remarkable loss of scatter is to be expected with such a change in flow direction, especially with high induction.

Therefore, according to the invention, the magnetic iron system 3 is formed with different cross sections in order to achieve a favorable overall efficiency again, so that the magnetic flux density at the deflection points is reduced, taking into account the permeability properties of the magnetic iron system 3.

According to the invention, the magnetic iron system with pipe guide, armature counterpart and housing has a cross section which is enlarged in comparison to the armature cross section at its points deflecting the magnetic field lines 2, at which a directly previous deflection angle changes. The armature cross section is designated Q1 in the illustration in FIG. With this configuration of the magnetic iron system 3, the magnetic field lines 2 can carry out a change in direction of the iron molecules with less power at a reduced flux density (compared to the flux density when running straight ahead) in order to bring about the desired change in the overall direction of the magnetic field.

It follows from this that with impulse magnetization, i.e. with impulse excitation of the excitation coil 1, a differentiated design of the induction is possible in the respective sections of the magnetic iron system 3, specifically to the extent that the straight magnetic field lines have a specially designed induction compared to practically right-angled deflection exhibit.

In addition to the armature cross section Q1, a further cross section Q2 is shown in FIG. This cross-section, referred to below as the conical base cross-section Q2, is the cross-sectional area that the magnet system 3 has at the level of its end wall 6. This conical cross-sectional area Q2 is consequently (disregarding the air gap) the armature cross-section Q1 plus twice the thickness of the wall between the excitation coil 1 and the magnetic displacement 13 in the cone area of the armature counterpart.

It can also be clearly seen in the illustration in FIG. 3 that the magnetic displacement 13 is arranged at least approximately centrally in the magnet system. This means that the magnetic displacement 13 lies at least approximately in the plane of symmetry S and also centrally to the coil plane A. Due to the shape of the magnet system according to the invention at its deflection points for the magnetic field profile, a maximum magnetization and thus lifting force control effect for the armature 5 in the magnetic displacement 13 can be achieved with the control cone walls 10, since this is also arranged centrally in the magnet iron system 3. In this way, novel tractive force curves can be achieved with relatively low electrical power. In addition, the electronic switching elements for controlling the magnet system according to the invention only need to switch lower powers. This central arrangement of the magnetic displacement 13 can take place independently of the thickness dimensioning of the magnetic iron system 3, but is the most effective in combination therewith.

Q1

die bereits erwähnte Querschnittsfläche des Ankers 5,

Q2

die bereits erwähnte Querschnittsfläche des Ankergegenstückes im Magneteisensystem 3 im Konusbasisbereich, im folgenden als Konusbasisquerschnittsfläche bezeichnet,

Q3

eine etwa zylindermantelförmige Schnittfläche im Bereich der ersten Umlenkung der magnetischen Feldlinien 2 zwischen Ankergegenstück und Gehäuse (hier die kreisrunde Schnittfläche links von der Symmetrieebene S in der axialen Verlängerung der innersten Spulenwicklung),

Q5

eine zylindermantelförmige Schnittfläche im Bereich der zweiten Umlenkung der magnetischen Feldlinien 2 zwischen der außenrohrartigen Wandung des Gehäuses des Magnetsystems 3 und einer dem Ankergegenstück zugeordneten deckelartigen Wandung des Gehäuses (hier die Schnittfläche im Magneteisensystem 3 in der axialen Verlängerung der äußeren Spulenwicklung im linken Teil des Magnetsystems 3),

Q6

die Querschnittsfläche der rohrartigen Außenwandung des Magneteisensystems 3 im Bereich der Symmetrieebene S,

Q7

entspricht der Schnittfläche Q5, allerdings im rechten Teil des Magneteisensystems 3 zur Symmetrieebene S,

Q9

entspricht Q3 für den rechten Teil des Magneteisensystems 3 und

Q10

die zylinderförmige Fläche zwischen Magneteisensystem 3 (hier der Rohrführungsbereich des Magneteisensystems 3) und dem Anker 5.

A specific application of the magnet system according to the invention is shown in FIG. 4 using a lifting magnet. The already known reference numerals continue to be used for the same parts. In the illustrated in Figure 4 The following cutting surfaces are listed for solenoids:

Q1

the cross-sectional area of the armature 5 already mentioned,

Q2

the cross-sectional area of the armature counterpart in the magnetic iron system 3 already mentioned in the cone base area, hereinafter referred to as the cone base cross-sectional area,

Q3

an approximately cylindrical jacket-shaped cut surface in the area of the first deflection of the magnetic field lines 2 between the armature counterpart and the housing (here the circular cut surface to the left of the plane of symmetry S in the axial extension of the innermost coil winding),

Q5

a cylindrical jacket-shaped cut surface in the region of the second deflection of the magnetic field lines 2 between the outer tube-like wall of the housing of the magnet system 3 and a cover-like wall of the housing assigned to the armature counterpart (here the cut surface in the magnet iron system 3 in the axial extension of the outer coil winding in the left part of the magnet system 3 ),

Q6

the cross-sectional area of the tubular outer wall of the magnetic iron system 3 in the region of the plane of symmetry S,

Q7

corresponds to the cut surface Q5, but in the right part of the magnetic iron system 3 to the plane of symmetry S,

Q9

corresponds to Q3 for the right part of the magnetic iron system 3 and

Q10

the cylindrical surface between the magnetic iron system 3 (here the pipe routing area of the magnetic iron system 3) and the armature 5.

$$\text{Q3 = (1,3 ... 2,5) x Q2,}$$

$$\text{Q5 = (2,2 ... 4,0) x Q2,}$$

$$\text{Q6 = (1,1 ... 2,0) x Q1}$$

und $$\text{Q10 = (3,0 ... 5,0) x Q2.}$$

According to the invention, the magnet iron system 3 satisfies the following conditions with regard to its dimensions: $$\text{Q2 = (1.2 ... 1.8) x Q1,}$$

$$\text{Q3 = (1.3 ... 2.5) x Q2,}$$

$$\text{Q5 = (2.2 ... 4.0) x Q2,}$$

$$\text{Q6 = (1.1 ... 2.0) x Q1}$$

and $$\text{Q10 = (3.0 ... 5.0) x Q2.}$$

FIG. 7 shows a diagram from which the sectional areas Q1 to Q10 shown in FIG. 4 are shown in relation to the anchor cross-sectional area Q1. If the individual cross sections are connected to one another on the basis of a line in the diagram in FIG. 7, the course denoted by I results for the magnet system according to the invention shown in FIG. 4. As can clearly be seen on the basis of this curve profile I, the cross-sectional area increases continuously from Q1 to Q5 and decreases continuously from Q7 to Q9. This avoids that sudden differences in flux density, which lead to losses, can occur in the magnetic circuit of the magnetic iron system 3.

To clarify the dimensioning of the magnetic iron system 3 according to the invention in comparison with the dimensioning in the prior art, in addition to the curve profile I according to the invention, there is also the iron cross-sectional situation represented by commercially available electromagnets (see curve II). This curve II shows a virtually constant flow cross-section for the entire magnetic circuit of the magnetic iron system.

Referring again to FIG. 4, the symmetrical structure of the magnetic iron system in combination with the arrangement of the excitation coil 1, which is rectangular in cross section, and the symmetrical position of the magnetic displacement 13, which is surrounded by the annular control cone walls 10, are shown there. At the same time, FIG. 4 shows the course of the magnetic field lines 2 when the armature 5 moves axially into the magnetic displacement 13. The plane of symmetry S again coincides with the end wall of the armature 5 in the starting position of the armature, the conical tip of the control cone wall 10 abutting the plane of symmetry S at least approximately .

From the representations of FIGS. 5 and 6, the advantage of the magnet systems according to the invention in comparison to conventional lifting magnets is also clear. FIG. 5 shows the traction force curves of the commercially available lifting magnets for continuous current operation (100% ED) and short-time operation (5% ED). The lifting force is plotted vertically in Ncm and horizontally the stroke in mm. FIG. 5 clearly shows the force characteristic curve running almost horizontally over the entire stroke, both for continuous operation and for short-term operation.

FIG. 6 shows the traction force curves of the magnet system according to the invention with the same electrical power and the same external dimensions. The course of the curve during continuous operation of the magnet system according to the invention shows a horizontal traction force curve over the majority of its stroke (approximately 80%), but increases in the remaining part of the stroke to an almost six-fold holding force (see point F in FIG. 6). The curve for short-term operation (5%) shows an approximately six to seven times increased initial lift force compared to the initial force during continuous operation (see point B in FIG. 6) and then increases continuously. The tractive force curve according to the invention is consequently designed for both types of load such that the holding force during continuous operation (point F at 100% ED) can apply the initial force during intermittent operation (point B at 5% ED) with complete certainty (see here the horizontally strongly emphasized comparison line FROM).

In addition, the magnet system according to the invention has a significantly higher flux density (induction) than the previously known lifting magnet systems and is characterized by better efficiency. When the armature reaches the end-of-stroke position, the electrical power can be switched to continuous operating power when the armature reaches the end of stroke, and the armature 5 then remains in the end-of-stroke position until the current is finally switched off and the armature returns to the initial stroke position.

FIG. 8 shows a further development of the magnet system according to the invention. The representation of FIG. 8 largely corresponds to the representation of FIG. 4, the magnetic iron system 3 being provided with bulges 20 on its edges in order to enlarge the curve radius for the magnetic field lines. These bulges 20 can also be used to specifically reduce the magnetic flux density at the deflecting points.

FIG. 9 also shows a lifting magnet, as has already been explained in FIG. 4. In addition to the presentation 4, the armature 5 is now provided with a short-circuit plate 32 on its outer surface 30, ie on its surface facing away from the armature counterpart. This short-circuit plate 32 has a larger diameter than the armature 5. In addition, the lifting magnet shown in FIG. 9 is provided with an annular recess 34 at the outer transition between armature 5 and magnetic iron system 3.

To perfect the magnetic field guidance of the longitudinally movable armature 5, it can be divided into two parts 5a and 5b. The anchor part 5b consists of a highly permeable special material. When the excitation coil is energized, this armature part 5b runs into the magnetic displacement 13 or working space. The length of this armature part 5b made of special magnetic material with the highest permeability (ie the material has a high saturation limit) is determined by the fact that at the end of stroke position plus an air gap distance between the armature counterpart and the end wall 8 of the armature 5, a sufficiently large piece of this part 5b in the tubular transition surface of the magnetic iron system 3 is present. The second armature part 5a of the armature 5 consists of conventional magnet soft iron material, the aforementioned short-circuit plate 30 being fastened to this second armature part 5a. This ensures that in the stroke end position of the armature 5, this short-circuiting plate 30 is magnetically short-circuited by lying on the outer wall of the magnetic iron system between the armature 5 and the pipe guide of the magnetic iron system 3. The ring-shaped recess, which acts as a bottleneck for the magnetic field lines, serves to increase this effect and thus to increase the holding force.

Although it was stated in connection with FIG. 9 that the anchor 5 consists of an anchor part 5b made of highly permeable material and an anchor part 5a made of soft iron material, the anchor 5 can of course be made entirely of the highly permeable material.

According to the invention, the transition surface Q10 from the magnetic iron system 3 to the movable armature 5 is to be made geometrically as large as possible in its tubular transition surface, since a magnetic resistance must necessarily be overcome by a few tenths of a mm in diameter. This design-related magnetic resistance is influenced during the lifting process of the armature 5 by the short-circuit plate 30 in the stroke end position.

In addition, the sectional view through the lifting magnet along the sectional line X-X is also shown in the illustration in FIG. From this sectional view it can be seen that the lifting magnet has a square outer contour. The area of the pipe routing of the magnetic iron system 3 is identified by 3a.

The lifting magnet shown in FIG. 9 has a magnetic iron system 3 which is assembled from two parts which are each formed in one piece. According to the invention, the housing butt joint 38 of these two parts is placed on or at least in the vicinity of the plane of symmetry S, since the magnetic field lines there run in a straight line.

A magnet system is shown in FIG. 10, the magnet iron system 3 having a housing with an outer circular shape and consisting of two essentially identically shaped, shell-like housing parts, each half of which surround the excitation coil 1. Also in this example the conditions described above with regard to cross sections Q1 to Q10 are observed. In contrast to the aforementioned exemplary embodiments, the pipe guide 3a of the magnetic iron system 3 is now designed as a separate component. The armature counterpart 3b of the magnetic iron system 3 is also formed separately. The entire magnetic iron system 3 consequently consists of the armature counterpart 3b, the shell-like housing 3c and the pipe guide 3a. The anchor counterpart 3b and the pipe guide 3a are inserted into one of the two tubular parts of the housing walls 3c and fixed there. It is important to ensure that there is no air gap between the individual elements 3a, 3b and 3c.

FIG. 11 shows an electromagnet similar to FIG. 10. The same reference symbols again designate the same parts. In contrast to the aforementioned exemplary embodiments, the magnet system has an armature 5 which has to actuate a hydraulic valve with a threaded connection 50. For this purpose, an annular intermediate element 18 made of non-magnetic material is arranged in a sealing manner between the opposite and spaced ends of the control cone wall 10 and the end of the pipe guide 12.

FIG. 11 again shows the separately formed armature counterpart 3b and the separately implemented pipe guide 3c of the magnet system 3. In addition, the magnet system in FIG. 11 consists of a tubular outer wall 3c and two cover walls 3d each arranged on the end faces of the magnet system. Here, too, the above-mentioned regulations regarding cross-sectional dimensioning (Q1 to Q10) and the symmetry conditions with regard to the magnetic displacement are observed. Such a magnet system can be used, for example, for pressure-tight Control magnets, but also for normal solenoids.

For a better understanding of the embodiment shown in FIG. 11, the illustrations in FIGS. 12 and 13 show the magnet system shown in FIG. 11 in a disassembled state. As can be clearly seen in FIG. 12, the magnetic displacement 13 is designed to be pressure-tight due to the insertion of the annular intermediate element 18 between the control cone 10 and the pipe guide 3c. Both the pressure-tight hydraulic pipe system shown in FIG. 12 and a magnetic core system with an armature operating in air, as shown for example in FIG. 10, can be inserted into the opening of the excitation system shown in FIG. 13.

In summary, it can therefore be stated that, in the magnet system according to the invention, all field deflection points have enlarged cross sections with regard to the armature cross section and, if possible, are designed without an air gap. The entire magnet system is arranged almost symmetrically to a plane of symmetry S, as a result of which the magnet system is practically divided into two equal halves of the magnetic energy content. The magnetic displacement 13 with its conical outer sheath lies both symmetrically to the axis A of the excitation coil 1 and in the plane of symmetry S of the magnetic iron system 3. The result of each of these individual measures leads to an increase in the lifting force characteristics compared to previous magnet systems. The measures can basically be used separately from each other. However, it is advisable to implement all of the measures presented in a magnet system in order to achieve the greatest possible increase in the lifting force characteristics compared to the previous magnet systems. so that with a continuous current power the tractive force characteristic has such a holding force that the high pulling force can be applied as a holding force at low continuous current power in the event of shock excitation.

An examination of the lifting force values and the power requirement of a lifting magnet according to the invention in comparison with a commercially available lifting magnet with the same external dimensions and the same lifting height has shown the following comparison values in normal operation and surge mode: Listed standard solenoid (stroke 10 mm) type A According to the invention new magnet system (stroke 10 mm) type B traction Holding force traction Holding force 100% ED continuous operation 6.2 watts 10 N 16 N 23 N 100 N 5% ED intermittent operation 83 watts 62 N 90 N 100 N 400 N

The table of the measured data shows that the magnet (type B) according to the invention has a holding force which is sufficiently large to be able to safely still apply about five times the initial lifting force in the case of shock magnetization.

REFERENCE SIGN LIST

1

Excitation coil

2nd

magnetic field lines

3rd

Magnetic iron system

3a

Pipe routing

3b

Anchor counterpart

3c

tubular housing

3d

Housing cover

4th

Piston rod

5

anchor

5a

first part of the anchor

5b

second part of the anchor

5e

Cylinder body of the armature

5f

Hollow cylinder body of the armature

5g

Cover part of the anchor

6

Front wall

7

Cylinder wall

8th

Face

10th

Control cone wall

11

Transition area

12th

End of pipe routing

13

magnetic displacement

15

Pipe routing

18th

Intermediate element

20th

Bulges

30th

outside surface of the anchor

32

Short circuit plate

34

Recess

36

Air gap

38

Butt joint

50

Threaded connection

mm

millimeter

N

Newton

S

Plane of symmetry

A

axis

Q1 ... Q10

Cut surfaces

I.

Curve

II

Curve

X-X

Cutting line

F, B,

Points

A ', B'

Points

y

axis

S-S

Cutting line

Claims (8)

1. Direct-current lifting magnet having a cylindrical armature (5) which can be moved along one axis (A), an excitation coil (1) disposed coaxially with respect to said armature (5) and a fixed magnet iron system (3) for conducting the magnetic field having a hollow-cylindrical tubular guide (3a) disposed coaxially with respect to the axis (A) and situated between armature (5) and excitation coil (1) and having an armature counterpart (3b) which is situated at a specified distance opposite the tubular guide (3a) and which has an end wall situated opposite the armature (5) and a hollow-cylindrical regulating conical wall (10) which points in the direction of the armature (5), which is also disposed coaxially with respect to the axis (A), which is situated between armature (5) and excitation coil (1) and which is disposed at the end face at a distance from the hollow-cylindrical tubular guide with the formation of an annular air gap, and also having an air-gap-free housing wall which is disposed around the excitation coil (1) and which links the armature counterpart (3b) and the tubular guide (3a), wherein a closed magnetic-field line pattern can be generated in the magnet iron system (3) by passing current through the excitation coil (1), characterized in that the magnet iron system together with tubular guide (3a), armature counterpart (3b) and housing wall (3c) has, at its points which deflect the magnetic field lines (2) and at which a deflection angle of the magnetic field line pattern changes or is established, a cross section which is in each case increased compared with the armature cross section (Q1) in order to reduce the magnetic flux density at the deflecting points.
2. Direct-current lifting magnet according to Claim 1, characterized in that the magnet iron system is provided with a cross-sectional area Q1 of the armature (5), a cross-sectional area Q2 of the magnet iron system (3) in the vicinity of the armature counterpart (3b) at the beginning of the wall of the regulating cone, a sectional area Q3 in the vicinity of a first deflection of the magnetic field between armature counterpart (3b) and housing walls (3c), a sectional area Q5 in the vicinity of a second deflection between the tubular housing wall (3c) of the magnet iron system (3) and the armature counterpart (3b), a cross sectional area Q6 of the tubular housing wall (3c) of the magnet iron system (3) and a cylindrical transition area Q10 between tubular guide (3a) and armature (5), and in that, to reduce the magnetic flux density at the deflecting points at which a deflection angle of the magnetic field line pattern changes or is established, the magnet iron system (3) fulfils at least to some extent the following conditions with regard to its cross sections: $$\text{Q2 = (1.2 ... 1.8) × Q1}$$

   

   $$\text{Q3 = (1.3 ... 2.5) × Q2}$$

   

   $$\text{Q5 = (2.2 ... 4.0) × Q2}$$

   

   $$\text{Q6 = (1.1 ... 2.0) × Q1}$$

   

   and $$\text{Q10 = (3.0 ... 5.0) × Q2}$$

   
3. Direct-current lifting magnet according to Claim 1 or 2, characterized in that the magnet iron system (3) together with the excitation coil (1) is formed at least approximately symmetrically with respect to a symmetry plane (S) extending parallel to the cross section (Q1) of the armature (5), in that an end face (8) of the armature (5) is disposed in an initial lifting position at least to some extent so as to be situated on said symmetry plane (S) and, starting from this point, can be moved up to the end wall (6) of the armature counterpart (3b) into a final lifting position, and in that a cone end of the hollow-cylindrical regulating conical wall (1) is disposed at least approximately so as to adjoin the symmetry plane (S).
4. Direct-current lifting magnet according to one of Claims 1 to 3, characterized in that the armature (5) has a length by means of which its surface (30) remote from the armature counterpart (3b) terminates flushly with an outside wall of the tubular guide (3a) of the magnet iron system (3) in the final lifting position.
5. Direct-current lifting magnet according to one of Claims 1 to 4, characterized in that the armature (5) is provided with a short-circuit plate (32) at its surface (30) remote from the armature counterpart (3b).
6. Direct-current lifting magnet according to one of Claims 1 to 5, characterized in that an annular recess (34) is disposed on an outside of the magnet iron system (3) between tubular guide (3a) and housing (3c).
7. Direct-current lifting magnet according to one of Claims 1 to 6, characterized in that the magnet iron system (3) is provided with bulges (20) at its points which deflect the magnetic field lines (2).
8. Direct-current lifting magnet according to one of Claims 1 to 7, characterized in that the regulating conical walls (10) of the armature counterpart (3b) are provided with a conical outside surface.

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