EP0935262B1 - Electromagnet - Google Patents

Description

The invention relates to an electromagnet, consisting of a current-acting coil, which generates such a magnetic field and moves an armature when energized, and the armature for driving a valve or other element is used, wherein the movement of the armature of one or more damping elements is dampened.

The aforementioned electromagnets have found wide use in the field of technology. They serve, for example, in textile machines for a quick weft insertion of the threads.

The above-described electromagnets are also used for controlling gaseous and liquid media (especially in liquid or hydraulic circuits), for example in a valve or as actuator or solenoid in life and time critical applications.

Especially the field of application in weaving machines or other textile machines requires a high efficiency of electromagnets. It is expected that the solenoids will reach highest lifetime requirements and switching frequencies. This results in considerable mechanical loads for the electromagnet and the movably mounted elements.

In German Patent 31 32 396 an electromagnet is described which uses elastic elements as a damping body, which absorbs the kinetic energy of the armature and thus avoids premature wear of the electromagnet.

In order to achieve the high clock frequencies, corresponding accelerations of the armature must be achieved. Of particular importance is the storage of the armature, since an inaccurate mounting of the armature can lead to a one-sided loading of the damping elements, which then preferably wear at these points and then jeopardize the entire usability of the device.

Due to the high frequencies and the heat development of the solenoid coil is considerable. Due to the design, this leads to larger air gaps in order to constructively take into account the thermal expansion of the components. On the other hand, this impairs the effective magnetic gaps and thus reduces the efficiency of the device.

From the document DE 35 02 730 a solenoid valve with a closure piece actuating armature is known, which is slidably housed in a magnetic sleeve through the guide sleeve, wherein the armature or the guide sleeve on one of the facing boundary surfaces at least over an axial portion of a coating identifies a plastic. In this case, the application of the coating, for example by spraying or brushing done. It is also possible to represent the coating by molding in a tool. Furthermore, the application of the coating of the magnet armature by immersing it in a polymerizable plastic is conceivable.

The invention is based on this prior art and has set itself the task of electromagnets such as Described initially to improve so that they have a greater average life and a higher efficiency.

To solve this problem, the invention is based on an electromagnet as described above and proposes an electromagnet, consisting of a current-acting coil, which generates such a magnetic field and moves an armature when energized, and the armature for driving a valve or other Element is used, wherein the movement of the armature is damped by one or more damping elements, wherein the armature runs on a Kunststoffgleitfläche, before, which is characterized in that the Kunststoffgleitfläche is formed of a sliding film made of plastic. By using a film, the problem of thermal expansion is cleverly solved because the inserted film undergoes a low thermal coupling due to the low mechanical contact with the other device and thus a smaller structural air gaps is necessary. It has also been found that the film storage of an exact and low-wear storage of the armature is used, whereby transverse forces or obliquity of the armature are optimally balanced, resulting in a relatively uniform loading of the damping elements. As a result, the one-sided wear of the damping elements is avoided, resulting in a high reliability and durability of the electromagnet.

The film storage has proven to be particularly resistant to wear. The thin-walled film saves space without compromising mechanical reliability or stability. Low and relatively precisely definable bearing gaps reduce the loss air gaps in the magnetic transition, which improves the magnetic properties of the magnet and thus also increases the efficiency. There is also an advantage in the production of the Device. In the known anchor guides the anchor runs on the inner surface of a tube. This tube has been created, for example, by drilling in a solid material. For the most accurate possible anchor guide, it was necessary to perform the hole in the pipe as accurately as possible. This high cost is saved by the proposal according to the invention. There are not any increased requirements regarding the surface quality of the pipe to consider more, since this task is taken over by the plastic tread, in particular by the inserted film. The solution according to the invention thus leads to a more cost-effective structure and a simpler installation of the device.

In addition to the use of a plastic film, it is also possible to slide the anchor on a suitably designed plastic surface. Here, this surface takes over the task of the film.

A further advantage of the embodiment according to the invention lies in particular in the possibility of compensating for dimensional tolerances in the production of the electromagnets by a corresponding variation of the thickness of the foil. So far, magnets that gave too much dimensional tolerance automatically resulted in a reject because the oversized air gaps limited the performance or efficiency of this device and thus this device was no longer usable for certain applications. Since the movable armature slides on a Kunststoffgleitfläche, the thickness of this surface can be adjusted so that optimum conditions prevail. When testing the devices can thus be compensated by an appropriate choice of film thickness dimensional tolerances during manufacture. This preference is repeated even when overhauling the devices. If, due to the high lifetime of the device, especially on the moving parts, worn, can be easily and inexpensively overhauled and restored by a replacement of these moving parts and the cooperating plastic sliding and possibly a thicker sliding surface, the device. The resulting advantages in the reusability and recyclability of the complex equipment are obvious.

In addition to the use of a plastic film is provided, for example, to use in the known anchor guide made of a special plastic bush, slides on the inner surface of the anchor. As a further variant, a plastic coating on the armature facing inner surface of the armature guide is possible.

By using the plastic film is achieved that the film can be easily removed, especially if the anchor can be easily removed from the core. In the case that the film is worn, it can be easily replaced and the device can be made operational again.

In a preferred embodiment of the invention, a modular construction of the electromagnet is provided, wherein for the armature with the armature guide and the coil each have their own assembly are provided which are detachably connected to each other. By such a configuration, a simple and inexpensive construction or assembly of the electromagnet is achieved. It is also possible to perform a simple maintenance of the electromagnet, since the corresponding assemblies are interchangeable if necessary. A detachable connection can be achieved for example by a corresponding screw or clamp connection. This not only results in an advantage in the assembly or the construction of the electromagnet, but it is also an advantage in the operation of the device achieved. Due to the separate configuration, a substantial thermal decoupling of the electromagnet or the coil on the one hand and the armature assembly on the other hand is achieved. Since the heat conduction takes place essentially by a direct contact of these two modules, the thermal contact can be reduced by a waiver or reduction of a direct connection, whereby the thermal problems, especially at the described high frequencies can be significantly suppressed, resulting in an increase the reliability of the device leads. Alternatively, it is also possible to build the device as a non-separable unit. Here, for example, solid, permanent connections are used. The assemblies to be joined together are welded together, for example, or caulked mechanically. It can also be provided a common Kunststoffverguß or the like to firmly connect the modules together.

Another advantage is achieved when the armature assembly is connected to a drive element, for example for a valve. In connection with the modular construction of the invention, the drive element, for example for a valve or for another element which is also mechanically formed, is favorably combined with the armature assembly. Due to the interchangeability, the coil assembly can interact with differently dimensioned armature and / or control elements. With a small number of components can thus be covered a wide range of applications of these electromagnets.

For the movement of the armature damping elements are provided, wherein the damping elements are arranged either on the moving armature or on shoulders of the armature guide, substantially stationary. Optimal damping is achieved by relatively large-area and / or large-volume damping elements. By appropriate selection of the damping elements, in particular with respect to the material of the surfaces and the volume of the damping element, it is possible to adjust the wear characteristics of the device. It should also be noted that the selection of the elastic damping element, in combination with the film storage or the design of the plastic sliding surface of the armature results in further parameters by which the wear parameters or other requirements can be set specifically.

It is advantageous if the function of the damping element is combined with a sealing function, in particular if the damping element serves as a sealing plate for the closure of a valve opening. Due to the double functionality of the damping element, construction volume is saved in the relatively small devices.

It has proved to be advantageous if the anchor running surface or the sliding foil consists of polytetrafluorethylene (PTFE). This material is characterized by a very low adhesion, that is, an adhesion or adhesiveness. Surfaces or liners made from such a material act like a "ball bearing". These surfaces allow a smooth running of the moving part. By reducing the mechanical resistances, so the frictional resistances achievable accelerations and thus the achievable switching times are favorably influenced. At the same time, the film carries little, whereby volume of construction is saved and due to the low specific weight and the weight fraction for storage is very low.

Further advantageous embodiments of the invention are described in the subclaims or shown in the accompanying drawings.

Fig. 1, 2, 4 und 5

ein vertikaler Schnitt durch verschiedene Ausführungsformen des erfindungsgemäßen Elektromagneten und

Fig. 3

ein vergrößertes Detail gemäß III aus Fig. 1.

In the drawing, the invention is shown schematically. Show it:

Fig. 1, 2, 4 and 5

a vertical section through various embodiments of the electromagnet according to the invention and

Fig. 3

an enlarged detail according to III of Fig. 1st

In Fig. 1 the electromagnet according to the invention is shown schematically.

Due to the modular structure, there is an armature assembly 1 and a coil assembly 3.

The coil assembly 3 in this case comprises the bobbin 30, which carries the wire windings. The coil 30 is connected to electrical contacts 34 with a corresponding electrical power supply. The winding is wound on a bobbin 33, wherein the bobbin 33 is provided substantially rotationally symmetrical to the coil axis 31.

The modular design also continues in the coil assembly. The coil 30, which is surrounded by a plastic sheath 35, in this case is inserted into the bracket 32 substantially at right angles to the coil axis 31. The bracket 32 has in each case an opening for the implementation of the coil assembly 3 on the two legs. The coil 30 is thus easily detached from the bracket 32. The bracket 32 serves e.g. the attachment. In a variant, the bracket 32 may also be surrounded by a plastic casing.

The coil assembly 3 is connected to the armature assembly 1 through the connection 4. As a compound 4, for example, a clamping ring 40 is provided. This can also be designed as a screw 41 (Fig. 5). As a connection in this case, in particular, a releasable connection is provided. This ensures that the armature assembly 1 and the coil assembly 3 can also be easily disassembled, for example, when the device must be repaired or overhauled.

The armature assembly 1 consists of several elements. At the anchor assembly 1, the tube tube 10 is provided, which coaxial with the coil axis 31 in the coil assembly 3 can be inserted. The tube tube 10 is thereby introduced through the corresponding holes of the bracket 32 in the previously used in this bracket coil assembly 3.

The tube tube 10 has at its upper end the core 12, which provides a magnetic guidance of the magnetic field generated by the coil 30. The core 12 protrudes into the interior of the coil 30th

The tube 11 is used to guide the armature 11. The armature 11 does not run directly on the inner wall of the Tubusrohres 10, but as in Fig. 1 example shown on a sliding surface 2 and a sliding film 20. This is shown enlarged in Fig. 3 , The tube tube 10 is thereby pushed onto the core 12 and caulked or welded. In the lower, inner region of the core 12, a peripheral gap 17 (FIG. 3) is provided in the lateral surface, which has been produced by simply turning off the core 12.

In the gap 17, the film 20 protrudes. By a certain jamming of the film 20 in the gap this is held on the circumference. The film consists of Polytetraflourethylene and causes a smooth running of the movable anchor body 15 on the inner surface of the Tubusrohres 10. In addition to the use of a film 20, it is also possible to produce the inner surface of the Tubusrohres either of a corresponding plastic or a corresponding coating on the Tubusrohr applied. The use of the film is simple in that the film is easy to produce in different thicknesses and can be assembled in appropriate dimensions. By pinching the film in the gap 17, this is also reliably held. Since the guiding function is provided by the film, no increased requirements must now be met for the inner surface quality of the tube tube be, whereby the costs for the production of the tube significantly reduce, since the tube can be edited with a simpler tool and in particular a subsequent surface treatment, for example grinding or polishing is no longer necessary.

According to the embodiment shown in Fig. 1, a separate element, the tube 10 was used in the bobbin 30, which has to take over the task of guiding the armature. However, the proposal according to the invention of a sliding foil arrangement can also be used with electromagnets in which the coil body has a recess in the interior and at the same time serves as a running surface for the armature. In particular, in such embodiments, the invention may be advantageous since the introduction of the Tubusses in addition to the better magnetic guide is also produced more accurately. The use of the slip film can also be exploited to compensate for production-related inaccuracies in the bore in the coil. In this variant of the invention, therefore, an additional, relatively complex and accurate to be manufactured element, namely the tube barrel, saved and replaced by the inventive design, and obtained a smooth and wear-resistant electromagnet. This results in an advantageous embodiment of the invention such that the Kunststoffgleitfläche is provided on the tube tube and / or the bobbin or the bore in the bobbin. It is also possible not to arrange the tube tube 10 over the entire length of the bobbin or its bore and to guide the anchor in sections either through the tube tube or the bobbin. Between the anchor body and the tube tube or the bobbin the plastic sliding surface is provided for example in the form of a coating of a separate element or a film.

The operation of the electromagnet according to the invention is essentially as follows:

The magnetic field generated by the coil 30 moves the movable armature 11 and anchor body 15 usually against the force of a return spring 14 such that the air gap 13 is closed upon application of the coil 30. By means of the stroke corresponding to the air gap 13, a device connected thereto, for example a valve or another element, can be correspondingly controlled, opened or moved. If the current through the coil 30 is turned off, the magnetic field collapses, whereby the magnetic attraction forces are lower than the spring force of the Rückholfelder 14 and the return spring 14 pushes anchor back away from the core 12 such that an air gap 13 is made.

The movement of the armature 11 and the anchor body 15 is limited in particular by damping elements 6.

The anchor body 15 has a flange 18 in its lower part. This flange 18 cooperates with a damping element 6, which adjoins above the flange 18. The damping element 6 in this case surrounds the armature 11 in an annular manner. The damping element 6 is preferably fixed in this case, ie does not move with the armature 11, in order thereby not to unnecessarily increase the moved mass. But it is also possible to design the damping element 6 movable with the armature 11 and the anchor body 15. This is particularly advantageous if an additional function, for example a sealing function, is to be triggered by the movement of the damping element 6. By the damping element, the kinetic energy of the armature, which is directed upward, collected in cooperation with the ring plate. The ring plate 19 in this case connects the tube tube 10, to which this is integrally formed with the valve body 7. For this purpose, screws 73 are provided. The valve body 7 in this case has in its upper, directed against the tube tube end 10 in the inner region a recess which is formed so that the damping element 6 can be accommodated. This recess 74 is limited by the ring plate 19th

To dampen the kinetic energy of the armature 11, which is directed downward, a damping element 6 is embedded in the armature on the lower end face of the armature 11, which acts as a sealing plate 60. In Fig. 1 in this case the closed position of a solenoid valve is shown, wherein the sealing plate 60 finally cooperating with the sealing surface 75 at the outlet opening 71 of the valve body 7. As a result, the inlet port 70 is separated from the outlet port 71 and interrupted. On the outside of the valve body 7, seals 72 are provided to tightly connect and connect the solenoid valve to the medium circuit (for example, liquid circuit) which is switched and controlled.

It has been found in an advantageous manner that the inventive design, also with regard to different media, has led to a long life of the device and a corresponding reliability at high efficiency.

It is known that dried air often acts abrasive on the storage and leads to a preferred wear. The use in oil sludge may be detrimental to the life of the device. Now, it has been found by the use of the plastic tread or the sliding film that they work reliably in a variety of operating media.

2, another embodiment of the electromagnet according to the invention is shown. In Fig. 1, a hydraulic or pneumatic assembly is connected by the valve body, in Fig. 2 it is provided that the anchor rod 16 which is connected to the armature 11 and the anchor body 15, a corresponding movement to a not further shown element transfers. Such an electromagnet can e.g. used in textile machines. Incidentally, the structure is substantially identical to the structure of FIG. 1.

It should be noted that the damping elements 6 are each not designed to be moving with the anchor body 15, but are formed substantially fixed. The flange 18 of the anchor body 15 in this case runs against the upper and lower damping element 6. Again, in the assembly 9, which also forms a guide 90 for the anchor rod 16, a recess 91 is provided, in which the flange 18 moves up and down. The guide 90 is in this case provided in an anchor rod guide 8 and is located at the lower end of the electromagnet. In a variant of the invention, it is of course also possible that the damping element moves with the anchor body 15. The movement of the armature 11 is in this case absorbed by the damping elements 6, wherein other elements of the electromagnet, in particular elements which are connected to the coil group 3, serve as an abutment and compensate for a part of the kinetic energy.

The upper damping element 6 serves as attachment of the film 20, such that, after the film 20 is inserted into the tube, the film is pulled in the recess 91 radially outward and is clamped by the axially slid damping element 6.

The damping element 6 and the sealing plate 60 are formed of suitable, elastic plastic. By choice of these materials and the choice of the quality of the sliding film 20 and the strength of the sliding film 20, it is possible to adjust the wear parameters of the electromagnet or the ease of use or the life according to the intended use.

In Fig. 1 and 2, the return spring 14 is arranged in the region of the air gap 13. It can also be provided that the bearing of the return spring 14 is equipped with further damping elements.

4, a further variant of the invention is shown. The anchor rod 16 is guided here in the core 12. When the armature 11 is tightened, the anchor rod 16 is displaced to the right, the air gap 13 being closed. In contrast to the embodiment according to FIG. 2, when the current is applied, the anchor rod 16 comes out here, in FIG. 2, the armature rod 16 is pulled into the electromagnet.

Again, the other structure is identical as in the example of FIG. 1, 2. That is, the tube tube 10 is equipped as part of the anchor assembly 1 with an inside sliding 2. In order to improve the sliding properties, the anchor body 15 has a plurality of slide rings 25. The slide rings in this case consist of a bronze alloy, which are welded or applied to the anchor body 15.

The tube tube 10 is interrupted in the region of the air gap 13 by an annular tube element 26, which may consist of a different material. Due to the variation of magnetizable, ferromagnetic or non-magnetic materials in this area, the switching characteristic of the magnet can be influenced accordingly. The annular tube member 26 is incorporated in the manufacture of the tube in this, for example, soldered or welded and afterwards turned off.

FIG. 5 shows a further example of the magnet according to the invention. Here, an electromagnet is presented, which is constructed in the same way as the examples of FIGS. 1, 2 and 4. This is a valve magnet, which in turn is closed or opened by a sealing plate 60, which also serves as a damping element 6, a valve opening. This magnet is also modular, that is, the armature assembly 1 is easily detachably arranged by the coil assembly 3. This is done e.g. by the connecting means 4, 41, which are hereby equipped as nuts with internal or external thread.

The claims now filed with the application and later are attempts to formulate without prejudice to the attainment of further protection.

The references cited in the dependent claims indicate the further development of the subject matter of the main claim by the features of the respective subclaim. However, these are not to be understood as a waiver of obtaining independent, objective protection for the features of the dependent claims.

Features that have hitherto been disclosed only in the description may be claimed in the course of the method as of essential importance to the invention, for example to distinguish from the prior art.

Claims (11)

1. Electromagnet comprising a coil which can be supplied with current which thus generates a magnetic field and moves an armature when supplied with current, and the armature serves for selecting a valve or another element, the movement of the armature being damped by one or more damping elements, the armature (11) running on a plastics sliding surface (2), characterised in that the plastics gliding surface is a sliding film (20) of plastics material.
2. Electromagnet according to claim 1, characterised by a modular construction where for the armature (11) with the armature guide and the coil (30) each time an individual assembly (1, 3) is provided which are connected to each other in a releasably way.
3. Electromagnet according to one or both of the preceding claims, characterised in that the armature assembly (1) comprises essentially a tube (10) in which the armature (11) is supported movably.
4. Electromagnet according to one or more of the preceding claims, characterised in that the armature assembly (1) with the tube (10) can be introduced into the coil assembly (3) coaxially to the coil axis (31), and can be fastened by a screwed or clamped connection (4, 40, 41).
5. Electromagnet according to one or more of the preceding claims, characterised in that the armature assembly (1) is connected with a selecting element (7), for example for a valve.
6. Electromagnet according to one or more of the preceding claims, characterised in that damping elements (6) are provided at the armature (11) and/or at one or more steps (91, 74) of the armature guide for damping the movement of the armature (11).
7. Electromagnet according to one or more of the preceding claims, characterised in that the damping element (6) arranged on the armature (11) serves as sealing plate (60) for the sealing of a valve opening (70, 71).
8. Electromagnet according to one or more of the preceding claims, characterised in that the armature (11) has sliding rings (25) interacting with the armature guide.
9. Electromagnet according to one or more of the preceding claims, characterised in that the sliding surface (2) of the armature or the sliding film (20), respectively, is polytetrafluorethylene (PTFE).
10. Electromagnet according to one or more of the preceding claims, characterised in that the plastics sliding surface (2) is provided on the tube and/or the coil former or the boring in the coil former.
11. Electromagnet according to one or more of the preceding claims, characterised in that the damping element (6) is designed in such a way that it is, with respect to the armature (11), stationary or movable.

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