CA2331715A1

CA2331715A1 - Magnet armature bearing, especially for proportional magnets and switching magnets in the area of hydraulics and pneumatics

Info

Publication number: CA2331715A1
Application number: CA002331715A
Authority: CA
Inventors: Gerhard Mutz; Peter Vincon; Henning Kaess
Original assignee: Individual
Current assignee: ETO Magnetic GmbH
Priority date: 1998-05-14
Filing date: 1999-05-12
Publication date: 1999-11-18
Also published as: DE19821741A1; WO1999059169A1; DE19821741C2

Abstract

The invention relates to an armature bearing for proportional magnets or switching magnets used in the area of hydraulics or pneumatics. The armature of a magnet of this type is guided inside a pressure pipe by two rings which are welded into said pressure pipe. Said rings project over the inner periphery of the pressure pipe with a ring bearing and guide the armature with minimum friction. The ring facing towards the pole core is the separating ring which consists of non-ferromagnetic material. This separating ring concentrates the magnetic flux between the pole core and the armature. The second separating ring, which is situated on the other end section of the pressure pipe, may advantageously also consist of a non-ferromagnetic material such as brass or non-ferromagnetic steel, for production-related technical reasons. The inventive bearing can either be produced by welding suitable bearing rings with inwardly projecting ring bearings in sections of pressure pipes or by applying rings by build-up welding in grooves with a V-shaped cross-section in a solid rough-turned component and forming the pressure pipe with the inwardly projecting ring bearings by turning out said component. The ring bearings can be equipped with axial oil grooves.

Description

Magnet armature bearing, especially for proportional magnets and switching magnets in the area of hydraulics and pneumatics The invention relates to a bearing arrangement of the generic type specified in the preamble of patent claim 1.
For the reliable switching of such. magnets, in which the movement of the armature performs predetermined switching functions via a switching rod which passes through the pole core, free-running, tilt-free guidance of the armature in the pressure tube is necessary.
A generic reciprocating electromagnet is disclosed by DE-A-44 38 I58. In this case, a thin-walled tube consisting of non-magnetic material is provided in order to center the pressure tube, the non-ferromagnetic ring and cone of the pole core and to guide the armature.
According to prior art which is in use within the company, it is also customary to guide the armature via a sliding foil with a low coefficient of friction.
In this case, the sliding foil, which preferably consists of Teflon, rests on the inner diameter over the entire circumference. With regard to guiding the armature, such a sliding foil has proven to be expedient, under the precondition that satisfactory seating of the foil inside the sliding tube was ensured. However, for manufacturing reasons, AMENDED PAGE

this precondition was not ensured. This is because the foil has to be cut very accurately in terms of its width, in order that no gap or overlap occurs. In addition., a precise indentation on the pole base and limitation of the stroke are necessary in order that the sliding foil cannot be thrown out. The length of the foil must be produced exactly in compliance with the dimensions, in order that said foil does not migrate out of the indentation. Furthermore, a uniform thickness of the foil at all points must be ensured. These aforementioned conditions make production more difficult, in particular automated production. In functional terms, this sliding foil bearing has the further disad.var_tage that, because of the full-area contact with little play, it is sensitive to dirt, that is to say even small dirt particles entering via the hole in the pole core can. have a detrimental effect on the displacement of the armature:.
DE-A-19 64 297 shows a magnetic closing sleeve between the poles of the electromagnetic actuating means of valves, said sleeve consisting of non-magnetic material, defining the distance between the two poles and being flush with the inner wall of the pressure tube.
DE-A-32 27 765 describes a proportional magnet in which the armature guidance is provided by sliding segments which are fixed to the surface of the armature or are formed as protrusions on the guide tube.
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US-A-5 986 530, which is not a prior publication, describes an electromagnet and a manufacturing method, in which first and second ferromagnetic pieces of an armature housing are separated by a non-ferromagnetic piece, which connects the two ferromagnetic pieces mechanically. The non-ferromagnetic piece is arranged and configured in such a way that, within the housing, it forms a first bearing, which interacts with a second armature bearing in order to carry the armature inside the armature chamber. Manufacture is carried out by a circumferential groove being formed in a solid cylindrical body, which later forms the armature housing, and a ring of non-ferromagnetic material being welded into said groove. The solid cylindrical body .is then bored out in order to form the armature housing.
The invention is therefore based on the object of providing a magnet bearing arrangement of the generic type which, while avoiding the aforementioned disadvantages, ensures a permanent, free-running switch-displacement function of the armature, and can be manufactured. simply, precisely and automatically.
The object set is achieved by the features specified in the defining part of patent claim 1. Accordingly, the invention is based on the finding that a reliable and permanent bearing of the armature is ensured if the non-ferromagnetic ring effecting the magnetic separation and AMENDED PAGE

consisting of brass, for example, together with a second bearing ring which acts at the other end of the armature, performs the bearing function. For this purpose, the non-ferromagnetic ring and the second bearing ring project inward beyond the inner diameter of the pressure tube.
According to a manufacturing process according to claim 4, the separation of the magnetic flux can be achieved by welding on a non-ferromagnetic ring to an appropriate rough-turned part, in addition to the magnetic separating ring, a bearing ring also being welded on at the other end.
The rough-turned part can then be machined out to form a pressure tube, the two bearing rings projescting appropriately beyond the inner diameter.
Expedient refinements of the invention emerge from the subclaims.
The invention will be described below, taking into consideration the prior art, using exemplary embodiments. In the drawing:
Fig. 1 shows an axial section of a magnet armature bearing representing the prior art;
Fig. 2 shows an axial section through a magnet armature bearing constructed in accordance with the invention;
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Fig. 3 shows a longitudinal section through the pressure tube constructed in accordance with the invention, with pole core but without magnet armature:; and Fig. 4 shows an axial section through a rough-turned part, from which the construction of the ~>ressure tube with pole core visible from Fig. 3 can be produced.
In all the figures, the pressure t:ube is designated by the reference symbol 10, and is connected via a magnetic separating piece to the pole core 12, which has a through hole 14 for an actuating rod and a screw-t:breaded connecting piece 16 to be led through. Inside the pressure tube 10, the armature 18 is displaceably mounted.
In the arrangement representing the prior art, according to Fig. 1, the magnetic separating piece is constructed as a ring 20 of brass or the like, whose inner wall is aligned with the inner wall of thE: pressure tube. The inner wall of pressure tube 10 and ring 20 is lined with a foil 22 of Teflon, which at both ends projects into annular indentations 24.
In the inventive magnet armature bearing according to Figs. 2 and 3, the non-ferromagnetic separating ring 30 projects inward with a ring bearing 32 be;rond the inner diameter of the pressure tube 10. A further ring 34 used for the bearing is arranged in the end portion of the pressure tube that faces away from the pole core 12. This bearing ring AMENDED PAGE

34 has an inwardly projecting ring bearing 36 corresponding to the ring bearing 32. These ring bearings 32 and 36 guide the armature 18 with minimum friction and low tolerances. In order to reduce the friction further, the ring bearings 32 and 36 can be equipped with axial oil guide grooves, not illustrated in the drawing.
The rings 30 and 34 can be inserted between portions of the pressure tube and welded or soldered to the pressure tube. The ring 30 effecting the magnetic .separation consists of non-ferromagnetic material, for example of brass or else non-ferromagnetic steel, for example Rema:nite. For reasons of expediency, the other bearing ring 34 consists of the same material.
An advantageous production method will be described below using Fig. 4. Fig. 4 shows a solid :rough-turned part 38 with ready-constructed pole core 12 and two annular grooves 40 and 42 of V-shaped cross section, into which metal rings 44, 46 are inserted by means of build-up welding. In a clamping and machining operation, the rough-turned part which can be seen from Fig. 4 is then finely machined, in order to produce the bearing body which can be seem from Fig. 3.
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List of reference symbols Pressure tube 12 Pole core 14 Through hole 16 Screw-thread connecting piece 18 Armature Ring 22 Foil 24 Indentations Non-ferromagnetic ring 32 Ring bearing 34 Bearing ring 36 Ring bearing 38 Rough-turned part Annular groove 42 Annular groove 44 Metal ring 46 Metal ring AMENDED PAGE

Claims

claims:

1. A bearing arrangement for the armature (18) of a magnet, especially a proportional magnet or a switching magnet in the area of hydraulics or pneumatics, the armature (18) being displaceable inside a ferromagnetic pressure tube (10), and an non-ferromagnetic ring (30) being arranged between pressure tube (10) and pole core (12) to concentrate the magnetic flux over the armature toward the pole base, wherein the non-ferromagnetic ring (30), in the pressure tube (10), projects inward with a first ring bearing (32) beyond the inner diameter of the pressure tube (10), wherein, in the end portion of the pressure tube (10) that faces away from the pole core (12), a further non-ferromagnetic ring (34) is arranged, which projects inward with a second ring bearing (36) beyond the inner diameter of the pressure tube (10), and wherein the armature (18) is guided by the two ring bearings (32, 36).

2. The bearing arrangement as claimed in claim 1, wherein the ring bearings (32, 36) have an axial length smaller than the rings (30, 34) bearing them.

3. The bearing arrangement as claimed in either of claims 1 and 2, wherein the ring bearings (32, 36) have axial oil guide grooves.

4. A process for producing a magnet bearing arrangement as claimed in claim 1, wherein annular grooves (40, 42) are machined into a solid rough-turned part (38), into which grooves non-ferromagnetic metal rings (44, 46) are welded in by build-up welding or soldered in, and wherein, in order to produce the pressure tube (10), the rough-turned part (38) is machined out with the inwardly projecting ring bearings (32, 36).