U.S. patent application number 14/571672 was filed with the patent office on 2019-08-29 for method for manufacturing a pole tube for an electromagnet.
The applicant listed for this patent is Robert Bosch GmbH. Invention is credited to Friedrich MOSER, Christof OTT, Klaus SCHUDT.
Application Number | 20190267174 14/571672 |
Document ID | / |
Family ID | 53275127 |
Filed Date | 2019-08-29 |
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United States Patent
Application |
20190267174 |
Kind Code |
A9 |
OTT; Christof ; et
al. |
August 29, 2019 |
Method for Manufacturing a Pole Tube for an Electromagnet
Abstract
A method for manufacturing a pole tube having two magnetic pole
tube components and having one nonmagnetic ring, which is situated
axially between the pole tube components, for an electromagnet, in
particular for a solenoid valve of an automatic transmission in a
motor vehicle, including the following: concentric configuration
and/or centering of the pole tube components and of the ring, in
particular on a centering pin; form-fitting connection, in
particular by extrusion coating and/or casting an exterior lateral
surface of the pole tube components and of the ring.
Inventors: |
OTT; Christof; (Asperg,
DE) ; SCHUDT; Klaus; (Nordheim, DE) ; MOSER;
Friedrich; (Magstadt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Robert Bosch GmbH |
Stuttgart |
|
DE |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20160172091 A1 |
June 16, 2016 |
|
|
Family ID: |
53275127 |
Appl. No.: |
14/571672 |
Filed: |
December 16, 2014 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01F 41/0020130101; F16K
31/0675 20130101; H01F 7/081 20130101; F16D 2500/1085 20130101;
F16D 2500/1022 20130101; H01F 2007/085 20130101; H01F 7/1615
20130101; H01F 7/1607 20130101; F16D 2048/0224 20130101; H01F 7/127
20130101; F16D 2500/5116 20130101; F16D 2048/0221 20130101 |
International
Class: |
H01F 7/16 20060101
H01F007/16; H01F 41/00 20060101 H01F041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 2013 |
DE |
10 2013 226 619.7 |
Claims
1. A method for manufacturing a pole tube for an electromagnet, the
method comprising: providing at least one of concentric
configuration and centering of the pole tube components and of the
ring, in particular on a centering pin; and providing a
form-fitting connection of the pole tube components and of the
ring; wherein the pole tube includes two magnetic pole tube
components and one nonmagnetic ring, which is situated axially
between the pole tube components.
2. The method of claim 1, wherein prior to the at least one of the
concentric configuration and the centering, at least one of the
following is satisfied: (i) grooves are applied to the lateral
surface of the ring; and (ii) knurls are applied to the lateral
surface of the pole tube components.
3. The method of claim 1, wherein the pole tube components and a
ring are used which have the same inside diameter.
4. The method of claim 1, wherein a ring is used which has a
smaller inside diameter than the magnetic pole tube components.
5. A pole tube for an electromagnet, comprising: a nonmagnetic ring
situated axially between a pole core and a magnet tube, the pole
core, the ring and the magnet tube being situated concentrically to
one another; wherein an exterior lateral surface of the pole core,
of the ring and of the magnet tube is extrusion coated using an
extrusion coating or casting material.
6. The pole tube of claim 5, wherein the ring has two conical
sections which face away from one another in the axial direction
and cooperate with conical sections of the pole core and of the
magnet tube.
7. The pole tube of claim 5, wherein the pole core and the magnet
tube have knurls on the exterior lateral surface and/or the ring
has grooves on the exterior lateral surface.
8. The pole tube of claim 5, wherein the ring is made of a metal
bearing material.
9. The pole tube of claim 5, wherein the pole core, the ring and
the magnet tube have the same inside diameter.
10. The pole tube of claim 5, wherein the ring has a smaller inside
diameter than the pole core and the magnet tube.
11. An electromagnet for a solenoid valve, comprising: a pole tube,
including a nonmagnetic ring situated axially between a pole core
and a magnet tube, the pole core, the ring and the magnet tube
being situated concentrically to one another, wherein an exterior
lateral surface of the pole core, of the ring and of the magnet
tube is extrusion coated using an extrusion coating or casting
material, and wherein the pole core, the ring and the magnet tube
have the same inside diameter; wherein a bearing foil is provided
between the pole tube and a lateral surface of an armature situated
in the pole tube.
12. The electromagnet of claim 10, wherein the ring has a smaller
inside diameter than the pole core and the magnet tube, and wherein
a friction bearing sleeve is situated between the pole tube and a
lateral surface of an armature in the pole tube on the side facing
away from the pole core.
13. The electromagnet of claim 11, wherein a coil is situated
around the extrusion-coated lateral surface of the pole tube.
14. The method of claim 1, wherein the electromagnet is for a
solenoid valve of an automatic transmission in a motor vehicle.
15. The method of claim 1, wherein the form-fitting connection is
provided by at least one of extrusion coating and casting an
exterior lateral surface of the pole tube components and of the
ring.
16. The pole tube of claim 5, wherein the ring is made of a bearing
material, which is brass or bronze.
17. The pole tube of claim 5, wherein the electromagnet is a
solenoid valve of an automatic transmission in a motor vehicle.
18. The pole tube of claim 5, wherein the extrusion coating or
casting material includes plastic.
19. The electromagnet of claim 11, wherein the solenoid valve is
for an automatic transmission in a motor vehicle.
20. The electromagnet of claim 13, wherein the coil is a copper
wire winding.
Description
RELATED APPLICATION INFORMATION
[0001] The present application claims priority to and the benefit
of German patent application no. 10 2013 226 619.7, which was filed
in Germany on Dec. 19, 2013, the disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for manufacturing
a pole tube, in particular for a solenoid valve of an automatic
transmission in a motor vehicle according to the description
herein. The present invention also relates to a pole tube for an
electromagnet, in particular for a solenoid valve of an automatic
transmission in a motor vehicle according to the definition of the
species in description herein. Furthermore, the present invention
relates to electromagnets for solenoid valves according to the
definitions of the species in the further description herein.
BACKGROUND INFORMATION
[0003] In modern automatic transmissions for passenger vehicles,
hydraulically operated clutches are used for changing gears. In
order for these shifting operations to take place without pressure
and not be noticeable by the driver, the hydraulic pressure on the
clutches must be adjusted with an extremely high precision
according to predefined pressure ramps. Electromagnetically
operated pressure control valves are used for this purpose. These
pressure control valves may be configured either as seat valves or
as slide valves.
[0004] Electromagnetic operation results in an electromagnetic
force which is proportional to the coil current and which operates
a hydraulic slide valve. For a high pressure precision, it is
advantageous if the electromagnet has a precise force-current
characteristic curve having a low variance of the force level. In
addition, the resulting magnetic force should be largely
independent of the position of the control piston or of the
armature in the slide valve, i.e., the electromagnet should also
have what may be a force-distance characteristic curve. A force
hysteresis, which depends on the direction of movement or the
direction of current, due to friction in the armature bearing or
due to a hysteresis during magnetization of the magnetic circuit
materials, should be avoided. Furthermore, a high force level of
the electromagnets during use of the electromagnetically operated
pressure control valves in automatic transmissions is
desirable.
[0005] It is believed to be understood from DE 10 2006 011 078 A1
that a two-piece pole tube including a pole core and a bearing
sleeve made of a thin nonmagnetic material may be provided to
supply a low-friction bearing. Patent document DE 10 2006 015 233
B4 discusses a one-piece pole tube, which has a thinly turned
location. Furthermore, DE 10 2006 015 070 A1 discusses a
three-piece pole tube, in which a nonmagnetic ring is welded
between two magnetic pole parts to prevent a magnetic short
circuit.
[0006] To achieve a high force level of the electromagnetic
actuating device, it is important for the radial air gaps between
the pole tube and the armature to be configured small, if desired.
Furthermore, even extremely minor eccentricities may result in an
asymmetrical magnetic field, and therefore, transverse forces,
which burden the armature bearing and cause increased friction. It
is therefore important to position the components centrally (if
desired) with respect to one another.
SUMMARY OF THE INVENTION
[0007] The problem on which the present invention is based is
solved by a method for manufacturing a pole tube having two
magnetic pole tube components and having a nonmagnetic ring
situated axially between the pole tube components for an
electromagnet, in particular for a solenoid valve, for an automatic
transmission in a motor vehicle. Advantageous refinements are
described herein. Features important for the present invention are
also found in the following description and in the drawings, where
the features may be important for the present invention, either
alone or in various combinations, without having to mention this
again explicitly.
[0008] The method according to the present invention includes the
steps: [0009] Concentric configuration and/or centering of the pole
tube components and the ring, in particular on a centering pin;
[0010] Form-fitting connection, in particular extrusion coating
and/or casting an exterior lateral surface of the pole tube
components and of the ring.
[0011] A pole core and a magnet tube may advantageously be used as
pole tube components. To accommodate an armature, the magnet tube
has a through-hole, which may have the same inside diameter as the
pole core. The pole tube components and the ring may be situated
concentrically to a median longitudinal axis of the pole tube or of
the centering pin. If the pole tube components and the ring are
extrusion coated and/or cast, then a blind hole in the pole core,
the through-hole in the magnet tube and the ring form a magnet
space to accommodate the armature situated displaceably in the pole
tube. Due to the concentric configuration and/or centering, a small
joint clearance may be achieved prior to extrusion coating, the
form-fitting connection being able to prevent a subsequent movement
of the connected components due to the extrusion coating. The air
gaps present in the magnetic circuit may be minimized due to the
concentric configuration. In particular the air gap between the
armature and the pole core, i.e., the radial air gap and the
so-called "recess step" and the radial air gap between the movable
armature and the magnet tube, which is referred to as a so-called
"secondary air gap," may be minimized. Consequently, a pole tube
having small radial air gaps in the "recess step" and in the
"secondary air gap" may be manufactured using the method according
to the present invention, so that high magnetic forces may be
implemented, on the one hand, and a low friction armature bearing
may be provided, on the other hand, since it is possible to prevent
transverse magnetic forces due to eccentricities in the pole tube
components and the nonmagnetic ring. Reworking of the armature
bearing surface bordering the magnet space may be avoided since
stresses cannot be introduced into the components, in contrast with
connecting the pole tube components to the ring with the aid of a
thermal joining method, such as welding, for example.
[0012] One advantageous refinement of the method provides that,
prior to the concentric configuration and/or centering, grooves are
applied to the lateral surface of the ring and/or knurls are
applied to the lateral surface of the pole tube components. A
better connection to the extrusion coating material or casting
material is achievable through the knurls and/or grooves. It is
advantageous to provide knurls on the magnetic components since
knurls have less influence on the magnetic cross section. Grooves,
which are advantageously easier to manufacture, may be provided on
the nonmagnetic ring.
[0013] Additionally, it is provided that the pole tube components
and a ring be used which have the same inside diameter. Thus, the
pole tube components and the ring may be pushed onto a centering
pin easily from above. Therefore, no special tool is required for
centering and for concentric configuration of the pole tube
components and the ring. If the pole tube components and the ring
have the same inside diameter, then an armature bearing surface,
which is largely without offset, may be provided.
[0014] Another advantageous embodiment of the present invention
provides that a ring is used which has a smaller inside diameter
than the magnetic pole tube components. The inside diameter of the
ring may be only slightly smaller than the inside diameter of the
pole tube components. The part of the ring extending in the
direction of the magnet space may be used as a protruding friction
bearing section for support of an armature in the pole tube. An
internal collet chuck is advantageously used as a tool for the step
of concentric configuration and/or centering since components
having different diameters may also be situated concentrically to
one another by using this tool. In particular, a ring made of a
bearing metal, in particular brass or bronze, may be used in this
embodiment. The effects of friction on the bearing location may be
minimized by using a ring made of bearing metal.
[0015] The underlying problem on which the present invention is
based is also solved by a pole tube for an electromagnet, in
particular for a solenoid valve of an automatic transmission in a
motor vehicle having the features of Claim 5. It is provided
accordingly that an external lateral surface of the pole core, of
the ring and of its magnet tube is extrusion coated using an
extrusion coating or casting material, in particular a plastic. As
explained at the outset, the air gaps present in the magnetic
circuit may be minimized in the "recess step" and in the "secondary
air gap" due to the concentric configuration. Consequently a high
magnetic force with a low friction armature bearing at the same
time may be provided with a pole tube according to the present
invention.
[0016] One advantageous refinement of the pole tube provides that
the ring has two conical sections facing away from one another in
the axial direction, which cooperate with conical sections of the
pole core and of the magnet tube. The conical sections therefore
may have the same angle on the ring, on the pole core and on the
magnet tube. During centering and/or concentric configuration of
the components, the conical sections may then engage in or mesh
with one another and ensure a high radial strength after the
form-fitting connection by extrusion coating and/or casting. Thus,
even at a high radial load, a decentering of the individual pole
tube components is avoidable.
[0017] In addition, it is advantageous if the pole core and the
magnet tube have knurls on the exterior lateral surface and/or if
the ring has grooves on the exterior lateral surface. As already
explained, a better connection to the casting material, for
example, to plastic, may be achieved by applying knurls and/or
grooves.
[0018] In addition, it is advantageous if the ring is manufactured
from a bearing metal, in particular brass or bronze.
[0019] The pole tube, the intermediate piece and the magnet tube
may have the same inside diameter. The pole tube components and the
ring may then be simply pushed onto a centering pin for the
manufacturing process.
[0020] Another advantageous embodiment of the pole tube provides
that the intermediate piece has a smaller inside diameter than the
pole tube and the magnet tube. When using a ring made of bearing
metal, the section of the ring extending into the magnet space may
then be used as a friction bearing section for supporting the
armature in the pole tube.
[0021] The problem on which the present invention is based is also
solved by an electromagnet for a solenoid valve having the features
described herein. The electromagnet therefore has a bearing foil
between the pole tube and a lateral surface of an armature situated
in the pole tube. An offset may occur on the armature bearing
surface in the concentric configuration of the pole tube components
and the ring at the same inside diameters of the components in each
case, this offset depending on the joint clearance prior to the
extrusion coating and/or casting; the offset in the armature
bearing surface may be compensated for by the flexibility of the
bearing foil, which may be manufactured from plastic or a
plastic-fiberglass.
[0022] Furthermore, the problem on which the present invention is
based is solved by an electromagnet for a solenoid valve having the
features described herein. Such an electromagnet has, on the side
which faces away from the pole core, a friction bearing sleeve
between the pole tube and a lateral surface of an armature situated
in the pole tube. When using a pole tube in which the ring has a
smaller inside diameter than the pole tube components, the part of
the ring extending in the magnet space may be used as the first
bearing point of the armature, and the friction bearing sleeve may
be used as the second bearing point. Thus a simple two-point
bearing which is inexpensive to manufacture is achievable.
[0023] In addition, it is advantageous if a coil, in particular a
copper wire winding, is situated around the extrusion-coated
lateral surface of the pole tube. The extrusion-coated lateral
surface of the pole tube may be used here as a coil carrier.
Because of the omission of thick-walled coil carriers, more space
for the copper wire winding may then be created, so that a higher
magnetic force may also be achieved.
[0024] Additional details and advantageous embodiments of the
present invention are derived from the following description, on
the basis of which the method shown in the figures and the specific
embodiments shown in the figures are described and explained in
greater detail.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 shows a flow chart of the method according to the
present invention.
[0026] FIG. 2 shows the individual method steps of a method
according to the present invention for manufacturing a pole tube
according to the present invention.
[0027] FIG. 3 shows a first specific embodiment of an electromagnet
for a solenoid valve according to the present invention.
[0028] FIG. 4 shows a second specific embodiment of an
electromagnet according to the present invention for a solenoid
valve.
DETAILED DESCRIPTION
[0029] FIG. 1 shows a flow chart for the method steps illustrated
in FIG. 2. In a first step S100, grooves and/or knurls, not shown
in FIG. 2 but indicated in FIGS. 3 and 4, are applied to a lateral
surface of the components shown in FIG. 2a.
[0030] According to FIG. 2, pole tube 10 has a pole core 12 and a
magnet tube 14. A nonmagnetic ring 16 is situated between pole core
12 and magnet tube 14.
[0031] In a second step S200, magnet tube 14, ring 16 and pole core
12 are attached to a centering pin 18 shown in FIG. 2b and are
thereby positioned concentrically to one another. In a step S300,
an external lateral surface 20 of pole core 12, magnet tube 14 and
ring 16 is then extrusion coated and/or cast using extrusion
coating or casting material, for example, plastic. This step is
also shown in FIG. 2c. FIG. 2d shows pole tube 10 after step S300
having an extrusion coating or casting layer 22 applied to exterior
lateral surface 20. Pole tube 10 according to FIG. 2d need not have
an offset on armature bearing surface 24 formed in the interior of
pole tube 10, i.e., between the inside diameters of pole core 12,
magnet tube 14 and ring 16. Due to the high centricity of pole core
12, magnet tube 14 and ring 16, armature bearing surface 24 may be
configured in such a way that small radial air gaps may be achieved
between armature bearing surface 24 and an armature, not shown in
FIG. 2, which may be situated displaceably in pole tube 10.
Therefore, a high level of magnetic force may be achieved, on the
one hand, and a low-friction armature bearing may be achieved, on
the other hand.
[0032] FIG. 3 shows a partial detail of a section through an
electromagnet 26 according to the present invention for a solenoid
valve having a pole tube 10 according to the present invention in a
first specific embodiment. A pole tube 10 in electromagnet 26 is
situated concentrically to a median longitudinal axis 28 of
electromagnet 26. Pole tube 10 includes a pole core 12 and a magnet
tube 14, both of which are made of magnetic material. Furthermore,
pole tube 10 includes a nonmagnetic ring 16. An extrusion coating
or casting layer 22 is molded onto an exterior lateral surface 20
of pole tube 12, of magnet tube 14 and of ring 16. This extrusion
coating or casting layer functions as a winding carrier for a coil
30 situated around it in the form of a copper wire winding. Coil 30
is delimited toward the outside by a cylindrical housing 32. On a
right side in FIG. 3, housing 32 is sealed with a cover 34. A flow
disk 36 is inserted at least partially into housing 32 on the side
which faces away from cover 34.
[0033] Flow disk 36 has a central opening (no reference numeral) in
which an operating pin 38 for a valve element is guided
displaceably. Operating pin 38 is operable by an armature 42
supported in pole tube 10 or in opening 40 in armature bearing
surface 24 and operable by an armature bolt 44 connected to
armature 42. Ring 16 has a conical section 46, 48 on each of its
sides facing pole core 12 and magnet tube 14. Conical section 46
extends at an angle 50 of approximately 30.degree. to median
longitudinal axis 28. Conical section 48 also extends at an angle
52 of approximately 30.degree. to median longitudinal axis 28. Pole
core 12 also has a conical section 54 on its side which faces ring
16, the angle of the conical section corresponding approximately to
angle 50 of conical section 46. Furthermore, magnet tube 14 also
has a conical section 56 on its side which faces ring 16, the angle
of this conical section corresponding approximately to angle 52 of
conical section 48. Knurls not shown in the figures are applied to
one exterior lateral side of pole core 12 and of magnet tube
14.
[0034] Furthermore, grooves 58 are applied to the exterior lateral
side of ring 16. Knurls and/or grooves 58 facilitate a connection
of pole core 12, magnet tube 14 and ring 16 to the extrusion
coating or casting layer 22. Due to conical sections 46, 48, which
cooperate with conical sections 54, 56, a high radial strength of
pole tube 10 is achievable by using the extrusion coating or
casting layer 22. Pole tube 10, shown in FIG. 3, has an
approximately constant diameter 60 in the magnet space. For
compensation of possible component offsets between pole core 12,
magnet tube 14 and ring 16 due to a joint clearance during the
manufacture of pole tube 10, a bearing foil 62, which is made of
plastic or plastic-fiberglass in particular, is provided in the
magnet space between pole tube 10 and armature 42. During operation
of electromagnet 26, shown in FIG. 3, armature 42 may be moved back
and forth in the magnet space with a high magnetic force and a low
friction, when coil 30 is energized and acts on operating pin 38
via armature bolt 44.
[0035] FIG. 4 shows a second specific embodiment of electromagnet
26 according to the present invention for a solenoid valve in a
second specific embodiment of pole tube 10 according to the present
invention. The components corresponding to the specific embodiment
shown in FIG. 3 are labeled with corresponding reference numerals.
Ring 16 of pole tube 10, in contrast with ring 16 of pole tube 10
in FIG. 3, has an inside diameter 64, which is slightly smaller
than diameter 60, i.e., than the diameter of pole core 12 and
magnet tube 14. Ring 16 of pole tube 10 shown in FIG. 4 is made of
a bearing metal, in particular bronze or brass. A peripheral
bearing location 66 may be provided for armature 42 in the magnet
space due to its smaller inside diameter 64.
[0036] Furthermore, a friction bearing sleeve 68 is inserted into
magnet tube 14 on the side facing away from pole core 12. This
friction bearing sleeve 68 provides a second bearing location 70
for armature 42. Consequently, a two-point bearing may be provided
in a simple manner without any offset between the components of
pole tube 10. Using pole tube 10 shown in FIG. 4, the radial air
gaps between armature bearing surface 24 and armature 42 may be
still further reduced, since in the exemplary embodiment shown in
FIG. 4, it is possible to omit the configuration of a bearing foil
62.
* * * * *