MAGNET ARMATURE BEARING, ESPECIALLY FOR PROPORTIONAL MAGNETS AND SWITCHING MAGNETS IN THE AREA OF HYDRAULICS AND PNEUMATICS

PALIERS D'ARMATURE D'AIMANT, NOTAMMENT POUR AIMANTS PROPORTIONNELS ET AIMANTS DE COMMUTATION DANS LE DOMAINE HYDRAULIQUE OU PNEUMATIQUE

English 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.

French Abstract

Dans un aimant proportionnel ou un aimant de commutation s'utilisant dans le domaine hydraulique ou pneumatique, l'armature est guidée à l'intérieur d'un tube de pression grâce au fait que dans ce dernier sont soudés deux anneaux qui font saillie, par un palier annulaire, sur la périphérie intérieure du tube de pression et guident l'armature sans frottement. L'anneau tourné vers le noyau polaire est l'anneau séparateur constitué d'un matériau non ferromagnétique, qui doit concentrer le flux magnétique entre le noyau polaire et l'armature. Le deuxième anneau séparateur situé à l'autre section terminale du tube de pression peut, pour des raisons techniques de fabrication, avantageusement être constitué également d'un matériau non ferromagnétique, par exemple du laiton ou de l'acier non ferromagnétique. La fabrication peut s'effectuer de telle manière que des anneaux de palier correspondants avec leurs paliers annulaires faisant saillie vers l'intérieur sont soudés dans des sections du tube de pression, ou bien grâce au fait que des anneaux sont appliqués par soudage par superposition dans des rainures de section en forme de V d'une pièce prétournée massive et que par alésage de cette dernière, le tube de pression est formé avec les paliers annulaires faisant saillie vers l'intérieur. Les paliers annulaires peuvent être munis de rainures de graissage axiales.

Claims

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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.

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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).

Description

CA 02331715 2000-11-10
08-02-2000 EP009903293
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,
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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
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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
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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
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Representative Drawing