Bond magnet for magnetically receiving a workpiece

Abstract

The invention relates to a holding magnet for magnetically holding a workpiece (W), comprising an electromagnet (2) and a permanent magnet (3), wherein the electromagnet (2) comprises a magnet housing (4) and a coil (5), wherein the magnet housing (4) at least partially encloses the coil (5), and wherein the magnet housing (4) comprises a first, inner pole body (6) and a second, outer pole body (7), as well as comprising an inner pole surface body (8) and / or an outer pole surface body (9), characterized in that the inner pole surface body (8) has at least one cavity (11) and / or the outer pole surface body (9) has at least one cavity (11).

Description

[0001] The invention relates to a holding magnet for magnetically holding a workpiece, comprising an electromagnet and a permanent magnet, wherein the electromagnet has a magnet housing and a coil, wherein the magnet housing at least partially encloses the coil and wherein the magnet housing has a first, inner pole body and a second, outer pole body, and further comprising an inner pole surface body and / or an outer pole surface body.

[0002] Permanent magnet excited, electrically switchable holding magnets, also known as permanent electro-holding magnets, are part of the generally known state of the art and have a wide range of applications, for example for the assembly of machine tools, as an assembly aid in mechanical and plant engineering, in construction and in recycling companies.

[0003] WO 2006 / 037765 A1 discloses a generic holding magnet with an electromagnet, comprising a magnet housing and a coil contained therein. The magnet housing consists of an outer ring body, providing an outer pole, and an inner ring body, providing an inner pole. An annular permanent magnet is mounted on a unit called the pole core. The permanent magnet and electromagnet interact with a plate called the armature plate. The permanent magnet generates the holding force, while the electromagnet generates a counter-field to release the armature plate from the holding magnet when necessary.

[0004] While such holding magnets have proven effective in practice, they have a limited holding force and are often bulky in their design. This leads to relatively high costs in relation to the required holding force and to an unnecessarily large holding magnet body.

[0005] Against this background, it is theAufgabe the present invention provides a holding magnet which is structurally further developed in such a way that a compact design is enabled while simultaneously low manufacturing costs.

[0006] To Lösung The invention proposes a holding magnet of the type mentioned at the outset to solve this problem, characterized in that the inner pole surface body has at least one cavity and / or the outer pole surface body has at least one cavity.

[0007] The basic idea of ​​the invention is to increase the efficiency of magnetic field generation by the holding magnet, in particular by the at least one permanent magnet and the magnetic coil, through an advantageous design of the pole body geometry. This allows for a reduction in manufacturing costs and a more compact design.

[0008] The advantage of cavities in the inner and / or outer pole surfaces lies in the fact that magnetic saturation is created in the remaining material of the respective pole surface. This maximizes the magnetic attraction force generated by the permanent magnet. Thus, either a stronger magnetic field can be generated with the same amount of material, or the same magnetic field strength can be achieved with less material. This results in advantages in terms of manufacturing costs. Furthermore, a more compact design of the holding magnet is possible.

[0009] In accordance with the invention, the pole surface bodies are designed, in the context of the cavity they provide, such that magnetic saturation is achieved. For the purposes of the invention, "saturation" means a saturation that is sufficiently high with regard to the intended use of the holding magnet, preferably more than 90%, more preferably more than 95%, and most preferably more than 98%. This saturation occurs in the area of ​​the cavity provided according to the invention. In the context of the invention, this means saturation that is formed at the edge of the cavity, i.e., not within the cavity, but in its immediate vicinity. As a result of the cavity provided according to the invention, there is an increase in saturation in the area of ​​the cavity, which leads to an increase in saturation also with regard to the entire surface provided by the respective pole surface body.The aforementioned percentages refer to the total saturation on these surfaces.

[0010] The cavity provided by each pole body is formed on the workpiece side. According to a first embodiment of the invention, the workpiece-side surfaces of the inner pole body and the outer pole body are approximately the same size in their geometric dimensions. Even in this embodiment, the desired increase in saturation is achieved as a result of the design according to the invention. However, according to a second embodiment, the workpiece-side surface provided by the inner pole body is significantly larger than the surface provided by the outer pole body. According to this embodiment, it is particularly advantageous, and therefore preferred, to provide increased saturation with respect to the inner pole body as a result of the design according to the invention.The cavity design according to the invention is particularly useful when the workpiece-side surfaces of the inner pole surface body on the one hand and the outer pole surface body on the other hand have different geometric dimensions.

[0011] The holding magnet designed according to the invention can, in principle, interact with any suitable workpiece. However, according to a particularly preferred embodiment, the workpiece is designed as an armature plate and, together with the holding magnet, forms an electromagnetic clutch and / or brake. In this case, a clutch and / or brake is provided which has a holding magnet according to the invention on the one hand and an interacting armature plate on the other, wherein the armature plate is in operative connection with both the permanent magnet and the electromagnet. The inner pole surface body and / or the outer pole surface body provided by the holding magnet are equipped with a cavity on the armature plate side, as described above.The invention, being eligible for protection in itself, relates to an electromagnetic brake or clutch comprising an electromagnet, a permanent magnet, and an armature plate cooperating with the electromagnet and the permanent magnet, which is arranged on a hub body in a rotationally fixed but axially displaceable manner, wherein the electromagnet has a magnet housing and a coil received therein, wherein the magnet housing has, on the armature plate side, an outer pole body providing an external pole and an inner pole body providing an internal pole, as well as an inner pole surface body and / or an outer pole surface body, wherein the inner pole surface body has at least one cavity and / or the outer pole surface body has at least one cavity.

[0012] The holding magnet is designed to magnetically grip a workpiece. This can mean that the holding magnet is configured to establish a magnetic connection with a workpiece that is at least partially ferromagnetic. Advantageously, the workpiece can then rest against the inner pole body and / or the outer pole body. This allows the holding magnet to be used in a variety of applications, for example, for mounting components in machine tools, as an assembly aid in mechanical and plant engineering, in construction, and in recycling operations. Furthermore, the holding magnet according to the invention can be used to position linear motors or linear drives. The workpiece can also be an armature plate, as described above. In this case, the workpiece, acting as an armature plate, together with the holding magnet, forms a clutch and / or a brake.

[0013] The at least one permanent magnet can be made of a hard magnetic material. Preferably, the permanent magnet consists of a neodymium or samarium alloy, in particular a neodymium-iron-boron alloy (NdFeB). Hard magnetic materials in general have the advantage of permanent magnetization. Samarium and neodymium alloys also have the advantage of enabling magnets with particularly strong magnetic fields and low manufacturing costs.

[0014] The magnet housing at least partially encloses the coil. This can mean that the magnet housing is positioned next to the coil in at least two spatial directions. However, it is also conceivable that the magnet housing is positioned next to the coil in all six spatial directions. The magnet housing may have one or more openings.

[0015] This can result in advantages regarding the formation of the magnetic field as well as regarding the protection of the coil from external influences, such as contamination.

[0016] The magnet housing can take on any possible shape. In an advantageous embodiment, however, the magnet housing assumes the form of a ring, with the axis of symmetry perpendicular to the plane in which the holding magnet contacts the workpiece. This allows for a particularly compact design of the holding magnet. Furthermore, the components required for a ring-shaped housing can be predominantly manufactured by turning processes, making them more cost-effective to produce compared to milled components.

[0017] The holding magnet has an inner pole body and / or an outer pole body. The holding magnet can therefore have one or two pole bodies. The inner pole body can be a separate component. However, the inner pole body can also be monolithically or metallurgically bonded to the outer pole body. Thus, the inner pole body can be provided by the inner pole body. Similarly, the outer pole body can be a separate component. However, the outer pole body can also be monolithically or metallurgically bonded to the outer pole body. Thus, the outer pole body can be provided by the outer pole body.

[0018] If the inner or outer pole surface body is designed as a separate component, advantages in terms of manufacturing costs can result. If the inner or outer pole surface body is monolithically or metallurgically bonded to the respective pole body, or especially if it is provided by the pole body, a more compact design of the holding magnet can be achieved. Furthermore, this can reduce the number of components required, which in turn can lead to a reduction in the manufacturing costs of the holding magnet.

[0019] The inner or outer polar surface body can consist of two or more components that are joined together by a joining process. This can offer the advantage that at least one cavity can be arranged as a hollow space inside the respective polar surface body.

[0020] A cavity can be a depression on the surface of a body whose longitudinal extent is significantly greater than its respective extent in the width or depth direction. In particular, a cavity can be a groove, i.e., a channel. A cavity can also be a depression on the surface of a body whose width is not significantly greater than its depth. The cavity can have any cross-section. In particular, the cavity can have a round, rectangular, or tapered cross-section.

[0021] A cavity can be a depression on a surface whose longitudinal extent is not significantly greater than its respective extent in the width or depth direction. In particular, a cavity can be a bore or a blind hole.

[0022] A cavity can be a space completely surrounded by the body.

[0023] According to a further feature of the invention, the inner and outer pole bodies are connected to each other by at least one connecting web. The connecting web can be an independent component that is positively or materially connected to the inner and outer pole bodies. Alternatively, the connecting web can be monolithically connected to the inner and / or outer pole bodies. In particular, the connecting web can be part of the inner and / or outer pole body.

[0024] The connecting bridge can continuously connect the inner and outer pole bodies. However, it is also possible for the connecting bridge to have breaks.

[0025] The advantage of a connecting bridge linking the inner and outer pole bodies lies in the fact that it avoids an air gap between the two pole bodies, which in turn reduces the magnetic resistance between the inner and outer poles. This increases the efficiency of the electromagnetic control of the holding magnet.

[0026] A cavity within the meaning of the present invention is a void in an otherwise predominantly solid body. The void may be completely enclosed by the body, or the void may itself form part of the body's surface. In particular, the void may interrupt an otherwise flat or uniformly curved surface. A void may be a void that was not introduced into a body for the purpose of receiving another element, in particular a fastening element. A void may be a void that is completely filled by the surrounding medium, in particular air.

[0027] According to a further feature of the invention, the inner pole body, the outer pole body and the connecting bridge are formed in one piece.

[0028] "One-piece" can mean that the inner pole body, the outer pole body, and the connecting web were manufactured together from a single raw component. However, "one-piece" can also mean that the inner pole body, the outer pole body, and the connecting web originally consisted of several components that were joined by a material-bonded joining process, particularly welding.

[0029] If the inner pole body, the outer pole body, and the connecting bridge are formed as a single piece, advantages can arise in terms of the manufacturing costs of the holding magnet. Furthermore, this allows for optimal selection of the geometry of the pole bodies and the connector, and in particular, avoids an air gap between the pole bodies and the connecting bridge. This results in a more compact holding magnet.

[0030] According to a further feature of the invention, it is provided that the outer pole body projects towards the workpiece relative to the inner pole body, and that the permanent magnet and the inner pole surface body are arranged on the inner pole body such that the permanent magnet is located between the inner pole body and the inner pole surface body and the workpiece-side surface of the inner pole surface body is in a plane with the workpiece-side surface of the outer pole body, or that the inner pole body projects towards the workpiece relative to the outer pole body, and that the permanent magnet and the outer pole surface body are arranged on the outer pole body such that the permanent magnet is located between the outer pole body and the outer pole surface body and the workpiece-side surface of the outer pole surface body is in a plane with the workpiece-side surface of the inner pole body.

[0031] The term "workpiece side" here refers to the side of the holding magnet that is designed to magnetically grip a workpiece. "Protruding" in this context can mean that the pole body protruding from the other pole body is located closer to the workpiece when such a workpiece has been gripped by the holding magnet.

[0032] By protruding one of the two pole bodies relative to the other on the workpiece side, the holding magnet has a stepped design. This creates a cavity to accommodate the permanent magnet and the pole body. This can result in a more compact design for the holding magnet.

[0033] According to a further feature of the invention, it is provided that the at least one cavity is designed as a circular groove, i.e. as a slot.

[0034] A groove can be a cavity whose longitudinal extent is significantly greater than its lateral and lateral extents. Circular can mean that the cavity extends along a circular path in its longitudinal direction. Circular can also mean that the cavity extends along a spiral across the polar surface.

[0035] If the cavity is designed as an annular groove, it can be incorporated into the pole surface body particularly cost-effectively, thus enabling more economical production of the holding magnet. Since the groove extends uninterrupted across the pole surface body, it can be particularly shallow to achieve the technical effect according to the invention, resulting in advantages regarding the compactness of the holding magnet.

[0036] According to a further feature of the invention, it is provided that the inner pole surface body and / or the outer pole surface body has several cavities, in particular arranged concentrically to each other.

[0037] If the inner and / or outer pole body has multiple cavities, the magnetic saturation according to the invention can be generated over the entire surface of the pole body. This can result in advantages regarding the compactness of the holding magnet. If the cavities are arranged concentrically to one another, they can be produced in a single setup when manufactured using a lathe. This allows for cost-effective production of the holding magnet.

[0038] According to a further feature of the invention, it is provided that the inner pole surface body and / or the outer pole surface body has several cavities arranged along one or more interrupted circular paths, preferably that the several cavities are arranged offset from one another along several concentric interrupted circular paths.

[0039] This can have the advantage that the cavities can be introduced into the pole surface body in a particularly cost-effective manner, so that the holding magnet can be manufactured at a lower cost.

[0040] In an advantageous embodiment, the cavities are designed as circular arc segments, bores, or blind holes. This makes the cavities particularly easy and therefore cost-effective to produce.

[0041] An interrupted circular path can be a circular path that is interrupted by parts of the polar surface body that do not have a cavity. Therefore, it is conceivable that the cavities that are part of the interrupted circular path do not assume a circular shape.

[0042] Cavities can be arranged offset from one another along several concentric, interrupted circular paths if, starting from the center of the circular paths, circular segments exist in which only a part of the circular paths contain cavities.

[0043] According to a further feature of the invention, it is provided that the at least one permanent magnet is provided by a ring body or several ring bodies, preferably arranged concentrically to each other, wherein the axial dimension of the at least one permanent magnet is smaller than the radial dimension between the inner diameter of the at least one permanent magnet and the outer diameter of the at least one permanent magnet.

[0044] If the permanent magnet is provided by a ring body, it can be manufactured particularly easily using a turning operation, allowing for cost-effective production of the holding magnet. If the axial dimension is smaller than the radial dimension, the permanent magnet can be integrated into the holding magnet in a particularly compact manner.

[0045] According to a further feature of the invention, it is provided that the flat side of the at least one permanent magnet is arranged parallel to the flat side of the inner pole body and / or to the flat side of the outer pole body.

[0046] This allows for a particularly compact design of the holding magnet.

[0047] The flat side of the permanent magnet can be the side of the holding magnet that has no curvature.

[0048] "Parallel" here means that there is an angle of less than 5 degrees, preferably less than 1 degree, more preferably less than 0.5 degrees, and more preferably less than 0.1 degrees, between the flat side of the inner or outer pole surface body on the one hand and the flat side of the permanent magnet on the other. In particular, "parallel" here means that only the deviations from parallelism that are unavoidable due to manufacturing tolerances are present.

[0049] Alternatively, according to a further feature of the invention, the permanent magnet and the associated pole body, i.e., the pole surface body arranged thereon, can be formed in one piece. In particular, it can be provided that the permanent magnet is equipped on the workpiece side with a cavity in the sense already described. In this case, this equipment constitutes the pole surface body.

[0050] According to a further feature of the invention, the depth of the at least one cavity is designed such that, in the unenergized state of the coil, magnetic saturation of the remaining material of the inner pole body and / or outer pole body occurs in the region of the respective at least one cavity. This saturation occurs on the side of the cavity, i.e., with respect to the surface of the pole body equipped with the cavity. The saturation takes place particularly at the edge of the cavity, i.e., not within the cavity itself. In certain embodiments of the cavity, the entire pole surface is advantageously brought into saturation, depending on the cavity's design in terms of size, depth, and / or geometric shape. It is therefore generally desirable to design the cavity in such a way that the desired saturation is achieved.A saturation of more than 90% is preferred, more preferred than 95%, and most preferred than 98%.

[0051] This increases the efficiency of the holding magnet, allowing the holding magnet to be manufactured more compactly and cost-effectively.

[0052] The depth of the cavity can be defined as the extent of the cavity in a direction perpendicular to the plane in which the holding magnet contacts the workpiece. Alternatively, the depth can be defined as the extent perpendicular to the flat side of the holding magnet.

[0053] The unenergized state of the coil can be the state in which no electric current flows through the conductors of the coil, and thus, in particular, the coil does not generate a magnetic field.

[0054] Magnetic saturation can be the state in which a further increase in the external magnetic field no longer results in a significant increase in the magnetization of the material. This can mean that all magnetic moments of the atoms in the material are maximally aligned.

[0055] The remaining material in the area of ​​the respective cavity can be that part of the polar surface body which is located along a projection of the cavity in a direction perpendicular to the surface of the polar surface body.

[0056] If cavities are located on both sides of the pole body, the combined depth of both cavities is such that, in the unenergized state of the coil, a magnetic saturation of the remaining material of the inner pole body and / or outer pole body occurs in the area of ​​the respective at least one cavity.

[0057] According to a further feature of the invention, it is provided that the inner pole body, the outer pole body and the connecting bridge form a magnetic pot, preferably that the magnetic pot is closed in the direction of the inner pole surface body and / or the outer pole surface body.

[0058] According to this preferred embodiment, the magnet pot, as part of the magnet housing, accommodates the coil of the electromagnet in the fully assembled state. This results in a single-piece component that serves both as an enclosure for the coil of the electromagnet and as a housing for the outer and inner pole bodies as well as the connecting bridge.

[0059] This results in a simplified design that is easy to manufacture and assemble, and also saves space and therefore material. Thus, the holding magnet can be manufactured cost-effectively and compactly.

[0060] According to a further feature of the invention, it is provided that the inner pole body and / or the outer pole body and / or the connecting bridge are formed from a soft magnetic material.

[0061] This allows the magnetically conductive cross-section in the permanent magnet's magnetic circuit to be increased, thus enabling more efficient use of the permanent magnet. This, in turn, allows the holding magnet to be manufactured cost-effectively and compactly.

[0062] A soft magnetic material is one that can be easily magnetized and demagnetized. In particular, a soft magnetic material is characterized by low coercivity, high permeability, low remanence, and low magnetic losses.

[0063] In an advantageous embodiment, the inner pole body and / or the outer pole body and / or the connecting bridge are made of iron, an iron alloy, ferrite or Permalloy.

[0064] The advantage of these materials lies in their particularly favorable soft magnetic properties, allowing the holding magnet to be manufactured in a particularly compact and inexpensive manner.

[0065] According to a further feature of the invention, it is provided that the at least one permanent magnet is arranged to the coil in such a way that a magnetic field generated by the coil in the energized state of the coil opposes the magnetic field generated by the at least one permanent magnet.

[0066] This allows the magnetic field generated by the permanent magnet to be at least partially neutralized, making it particularly easy to detach the workpiece from the holding magnet. This eliminates the need for additional devices to release the connection, enabling the holding magnet to be manufactured in a particularly cost-effective and compact manner.

[0067] As a result of the inventive design, constrictions are provided in the magnetic circuit in the area of ​​the pole faces. These constrictions are formed as cavities, for example in the form of depressions, and are located on at least one of the two pole face sides. These cavities can be designed, for example, as circularly arranged teeth, grooves, or spirals. This drives the magnetically conductive material on the pole face into magnetic saturation, generating the maximum possible attracting force. By limiting the constriction to the required location on the pole face, losses due to cross-sectional constrictions in irrelevant areas are reduced. By reducing losses in areas irrelevant to the attracting force and saturating the relevant areas, the attracting force can be increased without having to change the permanent magnets used or the material of the magnetically conductive material.

[0068] The effect of this method is greater the larger the polar surfaces are in relation to the other dimensions.

[0069] As already explained above, according to a special feature of the invention, it can be provided that the workpiece is designed as an anchor plate and forms an electromagnetically switchable clutch and / or brake together with the holding magnet.The invention therefore further proposes an electromagnetically actuated clutch or brake, comprising a holding magnet and an armature plate cooperating therewith, wherein the holding magnet comprises an electromagnet and a permanent magnet, wherein the electromagnet comprises a magnet housing and a coil, wherein the magnet housing at least partially encloses the coil, and wherein the magnet housing comprises a first, inner pole body and a second, outer pole body, and wherein the holding magnet comprises an inner pole surface body and / or an outer pole surface body, characterized in that the inner pole surface body has at least one cavity and / or the outer pole surface body has at least one cavity, or that the armature plate preferably has a cavity on the holding magnet side.

[0070] In the case of an electromagnetically actuated clutch or brake, the cavity according to the invention can therefore be provided by one of the pole surface bodies on the holding magnet side or by the armature plate that interacts with the holding magnet in the intended use. In the case of a cavity on the armature plate side, it is preferred that this cavity is provided by a surface of the armature plate that faces the holding magnet in the intended use. The armature plate thus carries the cavity on the holding magnet side.

[0071] Alternatively, it may also be provided that cavities are formed on both the pole surface body side and the anchor plate side.

[0072] Furthermore, such a clutch or brake can have the additional features already described above on the holding magnet side. This results in the advantages already described above for such a clutch or brake with reference to the holding magnet according to the invention.

[0073] Further features and advantages of the invention will become apparent from the following description with reference to the figures. These show: Fig. 1 shows a schematic sectional view of a holding magnet according to a first embodiment of the invention; Fig. 2a-2 shows a schematic side view of the pole surface body in cross-section; Fig. 3a-3 shows a schematic top view of the pole surface body; Fig. 4a and 4 show a schematic view of a permanent magnet; and Fig. 5 shows a schematic sectional view of a holding magnet according to a second embodiment of the invention.

[0074] Fig. 1 An exemplary holding magnet 1 according to the invention is shown in a schematic sectional view.

[0075] The holding magnet 1 serves to magnetically hold a workpiece W, which - as in Figur 1 shown - is attracted by the holding magnet 1 in the intended use case.

[0076] The holding magnet 1 has an electromagnet 2 and a permanent magnet 3.

[0077] The electromagnet 2 comprises a magnet housing 4 and a coil 5, wherein the magnet housing 4 at least partially encloses the coil 5, i.e., the coil 5 is at least partially contained within the magnet housing 4. For the purpose of containing the coil 5, the magnet housing 4 has a coil compartment 15. This compartment is closed at the rear of the magnet housing 4 by means of a flange 14. The flange 14 is plate-shaped and preferably detachably arranged on the magnet housing 4.

[0078] The magnet housing 4 has a first, inner pole body 6 and a second, outer pole body 7. The inner pole body 6 and the outer pole body 7 are connected to each other by at least one connecting web 10.

[0079] The holding magnet 1 further comprises an inner pole body 8 and / or an outer pole body 9. The inner pole body 8 has at least one cavity 11 and / or the outer pole body 9 has at least one cavity 11.

[0080] According to the in Fig. 1 In the illustrated embodiment, the holding magnet 1 is rotationally symmetrical about an axis of rotation designated Z. The holding magnet 1 serves to hold a workpiece W, which is magnetically attracted to the inner pole body 8 and to a contact surface of the outer pole body 7. The embodiment shown here does not have an outer pole body 9. However, embodiments are conceivable that have only an outer pole body 9 but no inner pole body 8. Likewise, embodiments are conceivable that have both an inner pole body 8 and an outer pole body 9.

[0081] The inner pole body 6, the outer pole body 7, and the connecting web 10 are formed in one piece. The outer pole body 7 projects from the inner pole body 6 on the workpiece side, with the permanent magnet 3 and the inner pole surface body 8 arranged on the inner pole body 6 such that the permanent magnet 3 is located between the inner pole body 6 and the inner pole surface body 8. The workpiece-side surface of the inner pole surface body 8 is in a plane with the workpiece-side surface of the outer pole body 7.

[0082] In another embodiment, not shown here, the inner pole body 6 projects from the workpiece side relative to the outer pole body 7, wherein the permanent magnet 3 and the outer pole surface body 9 are arranged on the outer pole body 7 such that the permanent magnet 3 is located between the outer pole body 7 and the outer pole surface body 9. The workpiece-side surface of the outer pole surface body 9 is in a plane with the workpiece-side surface of the inner pole body 6.

[0083] The inner pole body 6, the outer pole body 7 and the connecting bridge 10 are made of a soft magnetic material.

[0084] It is also in Fig. 1 It can be seen that the flat side of the at least one permanent magnet 3 is arranged parallel to the flat side of the inner pole body 8 and / or to the flat side of the outer pole body 9.

[0085] It is also in Fig. 1 It can be seen that the inner pole body 6, the outer pole body 7 and the connecting web 10 form a magnetic pot, the magnetic pot being closed in the direction of the inner pole surface body 8.

[0086] The magnetic pot houses the coil 5. The at least one permanent magnet 3 is arranged relative to the coil 5 such that the magnetic field generated by the coil 5 when the coil 5 is energized opposes the magnetic field generated by the permanent magnet 3.

[0087] The inner polar surface body 8 of the in Fig. 1 The embodiment shown has at least one cavity. In particular, the inner polar surface body 8 has several cavities.

[0088] The Fig. 2a - Fig. 2d The figures illustrate various embodiments of the cross-section of these cavities. The same cross-sections are also conceivable for the outer pole surface body 9.

[0089] The depth B of the at least one cavity 11 is designed such that, in the unenergized state of the coil 5, a magnetic saturation of the remaining material of the inner pole body 8 and / or outer pole body 9 occurs in the area of ​​the respective at least one cavity 11.

[0090] Fig. 3a - Fig. 3c reveal a partial top view of the inner polar surface body 8 or the outer polar surface body 9.

[0091] Again Fig. 3a As can be seen, at least one cavity 11 is designed as a circular groove. In particular, the inner polar surface body 8 and / or the outer polar surface body 9 has several cavities 11 arranged concentrically to one another.

[0092] According to another embodiment, as described in the Fig. 3b und Fig. 3c As shown, the inner polar surface body 8 and / or the outer polar surface body 9 has several cavities 11 arranged along one or more interrupted circular paths, with the multiple cavities 11 being offset from one another along several concentric interrupted circular paths. In a top view, the cavities can, for example, have the shape of a circular segment or a circle. However, other shapes, such as oval, rectangular, or triangular shapes, are also conceivable.

[0093] Fig. 4a und Fig. 4b The figures show the permanent magnet 3 in a top view and as a three-dimensional body.

[0094] The at least one permanent magnet 3 is provided by several concentrically arranged ring bodies 13, wherein the axial dimension A of the at least one permanent magnet 3 is smaller than the radial dimension between the inner diameter D1 of the permanent magnet 3 and the outer diameter D2 of the permanent magnet 3.

[0095] According to a further embodiment, the permanent magnet 3 can be formed from individual rectangular bodies arranged side by side. Each rectangular body represents a magnet, and the sum of these rectangular bodies forms the permanent magnet 3.

[0096] In Fig. 5 A second embodiment of a holding magnet 1 according to the invention is shown. According to the embodiment shown here, the holding magnet 1 is part of an electromagnetic clutch and / or brake that interacts with a workpiece designed as an armature plate, which is Fig. 5 Not shown for the sake of clarity.

[0097] In contrast to the first embodiment according to Fig. 1 The holding magnet 1 indicates Fig. 5 An outer pole body 7 on the one hand and an inner pole body 6 on the other hand, which provide workpiece-side pole surface bodies 8 and 9 that are approximately the same size in their geometric design, i.e., provide approximately equally sized surfaces on the workpiece side. In contrast, Fig. 1 An embodiment in which the inner pole body 8 is designed to be much larger with regard to its surface design than the outer pole body 9. Furthermore, the two holding magnets 1 differ according to the embodiments according to the Fign. 1 and 5 regarding the design and arrangement of the permanent magnet 3.

[0098] The design of the cavities 11 on the workpiece or armature plate side according to the invention brings about the advantage of magnetic saturation in the manner already described above. This advantage is all the more significant the larger the geometric dimensions in the workpiece-side surface design between the outer pole surface body 9 on the one hand and the inner pole surface body 8 on the other.

[0099] In the case of the electromagnetically switchable clutch and / or brake according to Fig. 5 It can be provided that the cavities 11 provided according to the invention are provided by the inner pole surface body and / or by the outer pole surface body in the manner already described above. Alternatively, it can also be provided that the Fig. 5The armature plate, not shown in detail, has a cavity 11 according to the invention. In this case, it is preferred that the armature plate provides such a cavity 11 on the magnet side, i.e., the cavity 11 is provided by a surface of the armature plate facing the electromagnet 2.

[0100] Alternatively, it can be provided that both a pole surface body 8 or 9, or both pole surface bodies 8 and 9, have a corresponding cavity 11, as does the anchor plate. In such a case, it is particularly preferred if the cavities 11 of the anchor plate on the one hand and the pole surface bodies on the other are arranged offset from each other.

[0101] The design of a cavity 11 according to the invention provides the previously explained advantage of magnetic saturation. Therefore, it is also irrelevant whether the cavity 11 is formed on the holding magnet side or the armature plate side. The only decisive factor is that such a cavity 11 is provided at all, whether it is provided by the armature plate or by one or both pole surface bodies 8, 9. Reference sign

[0102] 1 Holding magnet 2 Electromagnet 3 Permanent magnet 4 Magnet housing 5 Coil 6 Inner pole body 7 Outer pole body 8 Inner pole surface body 9 Outer pole surface body 10 Connecting bridge 11 Cavity 12 Ring body 13 Flat side 14 Flange 15 Coil space

Claims

1. Holding magnet for magnetically holding a workpiece (W), comprising an electromagnet (2) and a permanent magnet (3), - wherein the electromagnet (2) comprises a magnet housing (4) and a coil (5), - wherein the magnet housing (4) at least partially encloses the coil (5) and - wherein the magnet housing (4) comprises a first, inner pole body (6) and a second, outer pole body (7), as well as comprising an inner pole surface body (8) and / or an outer pole surface body (9), characterized by that the inner polar surface body (8) has at least one cavity (11) and / or the outer polar surface body (9) has at least one cavity (11).

2. Holding magnet according to claim 1, characterized by the fact that the inner pole body (6) and the outer pole body (7) are connected to each other by at least one connecting bridge (10).

3. Holding magnet according to claim 2, characterized by the fact thatthe inner pole body (6), the outer pole body (7) and the connecting bridge (10) are formed in one piece.

4. Holding magnet according to one of claims 1, 2 or 3, characterized by the fact thatthe outer pole body (7) protrudes on the workpiece side relative to the inner pole body (6), and that the permanent magnet (3) and the inner pole surface body (8) are arranged on the inner pole body (6) such that the permanent magnet (3) is located between the inner pole body (6) and the inner pole surface body (8) and the workpiece-side surface of the inner pole surface body (8) is in a plane with the workpiece-side surface of the outer pole body (7), or that the inner pole body (6) protrudes on the workpiece side relative to the outer pole body (7), and that the permanent magnet (3) and the outer pole surface body (9) are arranged on the outer pole body (7) such that the permanent magnet (3) is located between the outer pole body (7) and the outer pole surface body (9) and the workpiece-side surface of the outer pole surface body (9) is in a plane with the workpiece-side surface of the inner pole body (6).

5. Holding magnet according to one of claims 1 to 4, characterized by the fact that which at least one cavity (11) is formed as a circular groove.

6. Holding magnet according to claim 5, characterized by the fact that the inner polar surface body (8) and / or the outer polar surface body (9) has several cavities (11), in particular arranged concentrically to each other.

7. Holding magnet according to one of claims 1 to 4, characterized by the fact that the inner polar surface body (8) and / or the outer polar surface body (9) has several cavities (11) arranged along one or more interrupted circular paths, preferably that the several cavities (11) are arranged offset from each other along several concentric interrupted circular paths.

8. Holding magnet according to one of claims 1 to 7, characterized by the fact thatthe at least one permanent magnet (3) is provided by a ring body (13) or several ring bodies (13), preferably arranged concentrically to each other, wherein the axial dimension (A) of the at least one permanent magnet (3) is smaller than the radial dimension between the inner diameter (D1) of the at least one permanent magnet (3) and the outer diameter (D2) of the at least one permanent magnet (3).

9. Holding magnet according to claim 8, characterized by the fact that the flat side of the at least one permanent magnet (3) is parallel to the flat side of the inner pole body (8) and / or to the flat side of the outer pole body (9).

10. Holding magnet according to one of claims 1 to 9, characterized by the fact thatthe depth (B) of the at least one cavity (11) is designed such that, in the unenergized state of the coil (5), a magnetic saturation of the remaining material of the inner pole body (8) and / or outer pole body (9) occurs in the area of ​​the respective at least one cavity (11).

11. Holding magnet according to one of claims 1 to 10, characterized by the fact that the inner pole body (6), the outer pole body (7) and the connecting bridge (10) form a magnetic pot, preferably that the magnetic pot is closed in the direction of the inner pole body (8) and / or the outer pole body (9).

12. Holding magnet according to one of claims 1 to 11, characterized by the fact that the inner pole body (6) and / or the outer pole body (7) and / or the connecting bridge (10) are made of a soft magnetic material.

13. Holding magnet according to one of claims 1 to 12, characterized by the fact thatthe at least one permanent magnet (3) is arranged in such a way as to the coil (5) that a magnetic field generated by the coil (5) in the energized state of the coil (5) opposes the magnetic field generated by the at least one permanent magnet (3).

14. Electromagnetically actuated brake or clutch, comprising a holding magnet (1) and an armature plate interacting therewith, wherein the holding magnet (1) comprises an electromagnet (2) and a permanent magnet (3), wherein the electromagnet (2) comprises a magnet housing (4) and a coil (5), wherein the magnet housing (4) at least partially encloses the coil (5), and wherein the magnet housing (4) comprises a first, inner pole body (6) and a second, outer pole body (7), and wherein the holding magnet (1) comprises an inner pole surface body (8) and / or an outer pole surface body (9). characterized by the fact thatthe inner pole surface body (8) has at least one cavity (11) and / or the outer pole surface body (9) has at least one cavity (11) or that the armature plate preferably has a cavity (11) on the holding magnet side.

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