ELECTROMAGNETIC CLUTCH OR BRAKE

Description

[0001] The invention relates to an electromagnetic clutch or brake according to the preamble of claim 1.

[0002] Electromagnetic clutches or brakes are well known in the art. Reference is made, for example, to DE 32 17 715 A1 and EP 2 422 103 B1.

[0003] DE 32 17 715 A1 relates to an electromagnetically operated, slip-ringless clutch. This clutch comprises a clutch body with a drive shaft that transitions into an end plate at the front and has a clutch sleeve at the edge. To prevent a magnetic flux from short-circuiting in the clutch body during intended use, the end plate is interrupted by a welded-in ring made of magnetically non-conductive material. This separates the pole faces. Alternatively, milled openings can be provided to separate the pole faces. The webs separating the openings should be as large as possible to ensure sufficient strength of the clutch sleeve. Alternatively, straight slots can be milled into the end plate of the clutch body to separate the pole faces. The slots are arranged along an imaginary square.

[0004] EP 2 422 103 B1 discloses a method for producing a clutch and / or brake disc for an electromagnetic clutch and / or an electromagnetic brake. In this method, a circular slot is cut into a friction surface element by machining, thereby defining two pole surface rings. At least two webs are machined from the friction surface element in such a way that the slot shoulder of the webs, cut from the friction contact surface, is interrupted to form continuous air gaps.

[0005] Furthermore, reference is made to the documents DE 8 09 726 U, US 4 305 198 A, US 4 9951 797 A and DE 10 2009 016 716 A1.

[0006] From DE 8 09 726 U, it is known to achieve a separation of the pole faces in an electromagnetic clutch via circular grooves. In particular, it is provided that the connecting section of the magnet body is designed without any openings and has two circular grooves, and the armature plate is also designed without any openings and has one circular groove.

[0007] US 4,305,198 A discloses that the pole faces of an electromagnetic clutch are separated from each other by annular openings filled with a non-ferromagnetic material. A groove can be formed in the non-ferromagnetic material by pressing.

[0008] From US 4 9951 797 A a clutch disc for electromagnetic clutches or brakes is known, which can have several grooves on both sides of the disc.

[0009] From DE 10 2009 016 716 A1 a magnet housing for an electromagnetic clutch is known in which an inner ring and an outer ring form a circumferential groove.

[0010] Although the electromagnetic clutches or brakes described above, or the processes for manufacturing the corresponding clutch and / or brake friction discs, have proven themselves in everyday practical use, there is still room for improvement. Task The invention aims to propose a novel electromagnetic clutch or brake which enables simplified production and, if possible, simultaneous functional improvement.

[0011] To Solution To achieve this object, an electromagnetic clutch or brake having the features of claim 1 is proposed.

[0012] Three alternative embodiments are proposed. According to a first alternative, only the connecting section of the magnetic body is designed without any openings and has a circular circumferential groove. According to a second alternative, which is not part of the invention, only the armature plate is designed without any openings and has a circular circumferential groove. According to a third alternative, the first and second alternatives are combined with one another, so that both the connecting section of the magnetic body and the armature plate are designed without any openings and each have a circular circumferential groove.

[0013] With regard to the first alternative, the following advantages arise: The provided groove causes a pole separation between the inner pole on the one hand and the outer pole on the other hand, but at the same time, due to the connecting section, it is ensured that a sufficient mechanical connection is created between the first pole area and the second pole area, so that the structural integrity sufficient for proper operation is guaranteed.

[0014] The pole separation by means of the provided groove is achieved by a material taper in the connecting section as a result of the groove formation. This material taper minimizes the magnetic stray flux through the connecting section. In the area of ​​the groove, the connecting section can be reduced by half the material thickness of the connecting section, preferably by more than 50%, for example 60%, 70%, 80% or even 90%. In general, it can be said that the depth of the groove can be designed depending on the intended application, whereby the aim is to minimize the magnetic stray flux while at the same time ensuring a mechanically stable connection between the two pole areas. The groove should therefore be designed to be as deep as possible while maintaining the desired mechanical stability.

[0015] The groove is circular in shape. The magnetic body, which has a circular cross-section, is therefore equipped with a groove that runs circumferentially between the inner and outer poles, creating a circular, closed pole separation between the two poles.

[0016] The connecting section is designed without any openings. There are therefore no slots, holes, or other openings intended for pole separation. This makes it possible to create pole separation through turning alone. Milling, either as a standalone operation or in combination with turning, can thus be completely eliminated, which minimizes manufacturing effort and also contributes to minimizing manufacturing costs.

[0017] The result of the design explained above is that pole separation can be achieved solely by turning, which saves time and money. At the same time, improved stress distribution is achieved within the component, i.e. the magnetic body, as a circumferentially continuous geometry is provided in the design of the groove. Compared to magnetic bodies with partial recesses or openings, this allows either higher loads or, with consistently high loads, the use of materials with lower strength properties, such as low-alloy steels, which is more cost-effective. Since low-alloy steels also have better magnetic properties, this results in a technical advantage in addition to the cost advantage. This is because better magnetic properties allow higher magnetic forces to be generated on the armature plate, which leads to an increase in the transmittable torque.

[0018] Particularly in the case of an electromagnetic clutch, the connecting section also serves to accommodate a friction lining. This lining is typically glued to the connecting section for placement. In this context, the design of a perforation-free connecting section provides the advantage of a larger adhesive surface between the connecting section and the friction lining. This enables the transmission of larger forces or torques between the friction lining and the connecting section, i.e., the magnetic body.

[0019] The perforation-free design of the connecting section also proves advantageous during the manufacturing step of bonding the friction lining and connecting section, as there is no risk of adhesive accidentally dripping through the perforations. This allows for a simplified bonding process.

[0020] Particularly in electromagnetic brakes, but also in lining-free electromagnetic clutches, the described connecting section also serves as protection against the unwanted ingress of media, since the perforation-free design of the connecting section prevents media from passing through. The components covered by the magnetic body in the direction of medium feed are thus protected from unwanted media contact.

[0021] The intended groove can be advantageously formed by turning alone. Milling is therefore completely unnecessary. This has the advantage that no deburring is required, which is particularly advantageous for components with multiple flow paths.

[0022] The result of the design explained above is a construction with improved technical properties while simplifying production.

[0023] With regard to the second alternative, the following advantages arise: The design of equipping the armature plate with a circumferential groove has the positive effect that the desired magnetic flux is specifically directed multiple times over the armature plate. This leads to an increased attractive force and thus also to the possibility of transmitting higher torques. This resulting positive effect is not unknown in the prior art. However, openings, particularly in the form of holes and recesses, are sometimes used to deflect the magnetic flux, for example in accordance with the prior art known from DE 32 17 715 A1. As with the pole separation previously known from DE 32 17 715, openings of this type lead to a material weakening of the armature plate and, particularly for small series, necessitate comparatively costly production by milling.The design described above provides a remedy for this problem, as the armature plate is designed without any openings. Instead, a circumferential groove is provided which causes the material of the armature plate to taper to such an extent that the magnetic flux within the armature plate is minimized at this point, with the magnetic flux being redirected at this point of interruption and transferred into the magnet body. Radially offset from the circumferential groove in the armature plate, a material taper is provided in the magnet body so that the magnetic flux is redirected again at this point and transferred back into the armature plate. This advantageously creates a double-flux armature plate, which leads to the already explained effect of increased attractive force. The formation of a groove instead of openings provides the advantages already described with regard to the pole separation of the magnet body.

[0024] What both designs have in common is that the magnetic flux is influenced by the grooves incorporated. Instead of openings in the form of recesses, holes, or the like, perforations are provided to influence the magnetic flux, but instead, circumferential grooves are provided, thus ensuring that the respective component, i.e., the magnet body or the armature plate, is designed without any openings.

[0025] According to a third and preferred alternative, the two previously described alternatives are combined, whereby both the connecting section of the magnet body and the armature plate are each designed without any openings and each have a circular, circumferential groove. This combination achieves the synergistic effect of achieving both pole separation and increased attractive force, with the groove in the magnet body provided for pole separation also serving as a deflection point for the magnetic flux on the magnet body side for the purpose of double magnetic flux flow. The groove design in the magnet body thus serves, on the one hand, to minimize unwanted magnetic stray flux within the magnet body and, on the other hand, to deflect the desired magnetic flux from the magnet body into the armature plate.

[0026] As a result, the preferred third alternative offers the advantage of minimizing stray flux in the magnetic body, while also achieving increased attractive force through targeted redirection of the desired magnetic flux. The groove formed on the magnetic body side serves both to minimize stray flux and to redirect the magnetic flux, which is particularly advantageous in terms of simplified and more cost-effective production.

[0027] According to a further feature of the invention, the groove has a partially elliptical, preferably circular, or polygonal cross-sectional contour. Such a configuration can be formed particularly easily and, while simultaneously maintaining a certain degree of mechanical stability, ensures such a tapering of the connecting section that a pole separation is formed that allows only minimal stray flux.

[0028] According to a further feature of the invention, the groove is formed on a side of the connecting section facing the armature plate and / or on a side of the connecting section facing away from the armature plate. Depending on the machining accessibility of the magnetic body, a groove can therefore be provided either on one or the other side of the connecting section provided by the magnetic body. This creates a certain flexibility during production, which supports simplified manufacturing. If the groove is provided on the side of the connecting section facing away from the armature, this has the advantage of enlarging the friction surface facing the armature. This increases the wear volume and thus the service life of the clutch or brake.

[0029] Alternatively, a groove can be provided on both sides of the connecting section, i.e., on both the side of the connecting section facing the armature plate and the side of the connecting section facing away from the armature plate. Such a double-groove design can be advantageous, particularly for reasons of simplified manufacturing. Furthermore, optimized pole separation while maintaining the stability of the connecting section can be achieved, for example, by arranging the provided grooves offset in the radial direction.

[0030] According to a further feature of the invention, a second groove is provided which is radially spaced from the groove. According to this exemplary embodiment, not only one groove is used, but also a second groove. The two grooves are preferably arranged parallel to one another, while leaving a distance between them. The formation of two grooves is particularly important for correspondingly large connecting sections. This can further minimize stray flux. It is also possible, with regard to the relative position of the armature plate, to form one of the two grooves on one side of the connecting section and the other of the two grooves on the other side of the connecting section.

[0031] According to the invention, the side of the connecting section facing the armature plate carries a friction lining. This lining is bonded to the connecting section, whereby the inventive design provides the advantages already described above.

[0032] According to the invention, the friction lining is provided by a friction ring. Alternatively, the friction lining and connecting section can be directly bonded. The advantage of the friction ring design lies in simplified assembly and disassembly, especially in the event of repairs.

[0033] According to the invention, the friction ring is glued to the connecting section, which also leads to the advantages already mentioned above.

[0034] Furthermore, the invention provides that the side of the connecting section facing the armature plate has two radial shoulders. This means that a stepped design of the connecting section is provided. This is selected such that, according to a further feature of the invention, the friction lining or friction ring is carried by one of the two radial shoulders and ends flush with the other of the two radial shoulders. This enables positive insertion of the friction lining or friction ring, which also provides a centering aid. This allows for simplified handling during production. The design of the radial shoulders and the groove is preferably selected such that the groove is completely covered by the friction lining or friction ring in the finally assembled state. This results in a seamless, flush transition between the friction lining or friction ring on the one hand and the adjacent radial shoulder on the other.In the final assembled state, the friction ring may not be exactly flush, but rather forms a so-called pole face recess or projection by means of a projection or recess. In this case, the delta can be a few hundredths to a few tenths of a millimeter. For the purposes of the invention, such a pole face recess or projection is flush in the sense described above.

[0035] Further features and advantages of the invention will become apparent from the following description with reference to the figures. Fig. 1 schematically shows a partially sectioned side view of an electromagnetic clutch of the type according to the invention; Fig. 2 schematically shows a perspective view of a clutch rotor according to the invention of an electromagnetic clutch according to a second embodiment; Fig. 3 shows a partially sectioned side view of the clutch rotor according to Fig. 2; Fig. 4 schematically shows an electromagnetic brake in a partially sectioned side view; Fig. 5 schematically shows an electromagnetic clutch of the type according to the invention in a third embodiment in a partially sectioned side view and Fig. 6 schematically shows the electromagnetic clutch according to Figure 5 with magnetic flux drawn in.

[0036] Fig. 1 shows the embodiment according to the invention using an electromagnetic clutch 1 as an example.

[0037] The electromagnetic clutch 1 has, in a manner known per se, an electromagnet 3, which in turn has a magnet housing 4 which accommodates a coil 5.

[0038] A magnetic body in the form of a clutch rotor 2 with a circular cross-section is provided, rotatable relative to the electromagnet 3. This interacts with an armature plate 6, which is arranged at a distance from the end face of the clutch rotor 2, leaving a gap.

[0039] The clutch rotor 2 provides a first pole region 7 and a second pole region 8, which, when the electromagnet 3 is energized, provide an outer pole 9 and an inner pole 10, respectively.

[0040] Between the first pole region 7 and the second pole region 8, a connecting section 11 is formed, which has a pole separation for separating the two poles 9 and 10. According to the invention, this pole separation is formed by a groove 12 that runs circularly around the clutch rotor 2, with the connecting section 11 otherwise being designed without any openings.

[0041] The reference to the drawing plane according to Fig. 1 The arrows 15, 16 and 17 shown on the right schematically represent the course of the magnetic flux when current is applied to the coil 5. Technically speaking, only the magnetic flux as shown by arrows 15 and 16 is actually desired. Arrow 17 represents the unwanted leakage flux. This is accepted in order to be able to provide a one-piece clutch rotor 2 whose outer pole 9 and inner pole 10 are mechanically connected to one another with sufficient strength. The magnitude of the leakage flux depends on the residual cross-sections between the outer pole 9 and inner pole 10. The residual cross-section is therefore kept as small as possible while taking mechanically sufficient strength into account, i.e. the connecting section 11 is tapered as much as possible in the area of ​​the groove 12 by forming the groove 12.

[0042] According to the embodiment shown in Fig. 1The groove 12 is formed on the side 14 of the connecting section 11 facing the armature plate 6. A receiving area 13 is formed between the connecting section 11 and the armature plate 16, into which a friction lining or a friction ring equipped with a friction lining can be inserted flush with the end face of the clutch rotor 2. To connect a friction lining or a friction ring to the clutch rotor 2, the friction lining or friction ring can be glued to the clutch rotor 2.

[0043] The Figures 2 and 3reveal a further embodiment of a clutch rotor 2. According to this embodiment, the connecting section 11 is equipped with radial shoulders 18 and 19, wherein a friction ring 20 with a friction lining 21 is inserted into a receiving space provided by the radial shoulder 18, in such a way that the friction ring 20 with its friction lining 21 is flush with the other radial shoulder 19. The groove 12 provided according to the invention is completely covered by the friction ring 20. This not only creates a quasi-material connection by adhesive bonding, but also a positive fit due to the insertion of the friction ring into the receptacle provided by the radial shoulder 19, which is particularly useful for centering during assembly.

[0044] Fig. 4 shows the embodiment according to the invention using the example of an electromagnetic brake 22, which is Fig. 4is shown in detail. An armature plate 6 and an electromagnet 3 can be seen, wherein the electromagnet 3 has a magnet housing 23. This is formed in two parts and has a magnet housing pot 24 serving as the magnet body and a magnet housing back 25. In the final assembled state, the magnet housing 23 accommodates a coil 5 in a conventional manner.

[0045] As already explained above with reference to the electromagnetic clutch, the magnet housing pot 24, which serves as the magnetic body, provides a first pole region 7 and a second pole region 8, which are coupled to one another via a connecting section 11 to ensure sufficient mechanical stability. During intended use, a stray flux flows through this connecting section 11 as indicated by arrow 17. To minimize this stray flux, pole separation is provided in the form of a groove 12 that is designed to run in a circular manner. Furthermore, the connecting section 11 is designed to be open-ended. The actual desired magnetic flux is represented by arrows 15 and 16.

[0046] Furthermore, the above statements regarding electromagnetic clutch 1 apply accordingly.

[0047] A third and preferred embodiment is shown in the Figures 5 and 6In addition to the embodiments according to the Figures 1 to 4 is according to the embodiment according to the Figures 5 and 6 It is provided that both the connecting section 11 of the magnetic body 2 and the armature plate 6 are designed without any openings, wherein both the connecting section 11 has a circular circumferential groove 12 and the armature plate 6 has a circular circumferential groove 27. The connecting section 11 further has a second circumferential groove 26, which is radially spaced from the first circumferential groove 12. The groove 27 provided by the armature plate 6 is arranged in the radial direction between the two grooves 12 and 26, as can be seen in particular from the illustration according to Figure 5 results.

[0048] The groove 12 provided on the magnet body side serves to separate the poles, as already explained above with reference to the Figures 1 to 4 The embodiment according to the Figures 5 and 6The additional grooves 26 and 27, in combination with groove 12, serve to deflect the desired magnetic flux. This creates a double-flux coupling 1, which advantageously results in an increased attractive force between the armature plate 6 and the magnet body 2.

[0049] The deflection of the desired magnetic flux results in particular from the representation according to Figure 6 , according to which the resulting magnetic flux is represented by corresponding arrows 15 to 17 and 28 to 30.

[0050] The resulting magnetic flux is shown in the arrows 15, 19, 29 and 16. This magnetic flux is deflected as a result of the design of the grooves 26 and 30, as can be seen in particular from the illustration according to Figure 6 "Deflection" in the sense of the invention means that the magnetic flux initially passes from the magnet body 2 to the armature plate 6. This transition is enforced by the groove 26.

[0051] The magnetic flux then jumps from the armature plate 6 back to the magnet body 2. This redirection is enforced by the groove 27 on the armature plate side. The magnetic flux then jumps from the magnet body 2 back to the armature plate 6, due to the groove 12. As a result, a double magnetic flux flow through the armature plate 6 is achieved.

[0052] A leakage flux drops off at the respective grooves 12, 27 and 26, as symbolized by the arrows 17, 28 and 30. Reference symbol

[0053] 1 Electromagnetic clutch 2 Clutch rotor (magnetic body) 3 Electromagnet 4 Magnet housing 5 Coil 6 Armature plate 7 First pole area 8 Second pole area 9 Outer pole 10 Inner pole 11 Connecting section 12 Groove 13 Mounting area 14 Side 15 Magnetic flux (arrow) 16 Magnetic flux (arrow) 17 Leakage flux (arrow) 18 Radial section 19 Radial section 20 Friction ring 21 Friction lining 22 Electromagnetic brake 23 Magnet housing 24 Magnet housing pot (magnetic body) 25 Magnet housing back 26 Groove 27 Groove 28 Leakage flux (arrow) 29 Magnetic flux (arrow) 30 Leakage flux (arrow)

Claims

1. Electromagnetic clutch or brake with a magnet body (2, 24) of circular cross-section and an armature plate (6) interacting with it, wherein the magnet body (2, 24) has a first pole region (7) and a second pole region (8) radially spaced therefrom, the first pole region (7) providing an external pole (9) and the second pole region (8) providing an internal pole (10), wherein a connecting portion (11) is formed between the first pole region (7) and the second pole region (8), wherein the connecting portion (11) of the magnetic body (2, 24) is designed free of breakthroughs and has a circular circumferential groove (12), characterized in that the side (14) of the connecting portion (11) facing the armature plate (6) has a friction lining (21) which is provided by a friction ring (20), the friction ring (20) being glued to the connecting section (11), and that the side (14) of the connecting portion (11) facing the armature plate (6) has two radial shoulders (18, 19), the friction ring (20) being supported by one of the two radial shoulders (18, 19) and terminating flush with the other one of the two radial shoulders (18, 19).

2. Electromagnetic clutch or brake according to claim 1, characterized in that the groove (12) has a partially elliptical, preferably partially circular or polygonal cross-sectional contour.

3. Electromagnetic clutch or brake according to claim 1 or 2, characterized in that the groove (12) is formed on the side (14) of the connecting portion (11) facing the armature plate (6).

4. Electromagnetic clutch or brake according to any one of the preceding claims, characterized in that a second groove (26) is provided which is radially spaced from the groove (12).

5. Electromagnetic clutch or brake according to any one of the preceding claims, characterized in that the armature plate (6) is formed free of breakthroughs and has a circular circumferential groove (27).

6. Electromagnetic clutch or brake according to claims 4 and 5, characterized in that the groove (27) provided by the armature plate (6) is arranged in the radial direction between the two grooves (12, 26) of the magnetic body (2, 24).

7. Electromagnetic clutch or brake according to any one of the preceding claims, characterized in that the groove (12) of the connecting portion (11) is completely covered by the friction ring (20).