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.

Claims

1. A method for manufacturing a pole tube for an electromagnet, the method comprising: concentrically aligning (a) a first magnetic pole tube component, (b) a second magnetic pole tube component, and (c) a nonmagnetic ring arranged axially between the first and second magnetic components; form-fittingly connecting the concentrically aligned (a) the first magnetic component, (b) the second magnetic component, and (c) the nonmagnetic ring; and extrusion coating a coating material onto exterior lateral surfaces of the nonmagnetic ring, first magnetic pole tube component, and the second magnetic pole tube component, wherein the coating material is molded onto and in contact with the exterior lateral surfaces of the nonmagnetic ring, the first magnetic pole tube component, and the second magnetic pole tube component, wherein, prior to the concentrically aligning, grooves are applied to the lateral surface of the ring.

2. The method of claim 1, wherein, prior to the concentrically aligning, knurls are applied to the lateral surface of the pole tube components.

3. The method of claim 1, wherein the pole tube components and the ring have the same inside diameter.

4. The method of claim 1, wherein an interior diameter of the ring is smaller than an interior diameter of the magnetic pole tube components.

5. The method of claim 1, wherein the electromagnet is for a solenoid valve of an automatic transmission in a motor vehicle.

6. The method of claim 1, wherein the concentrically aligning is performed on a centering pin.

7. The method of claim 1, wherein the application of the coating is applied by casting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a flow chart of the method according to the present invention.

(2) 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.

(3) FIG. 3 shows a first specific embodiment of an electromagnet for a solenoid valve according to the present invention.

(4) FIG. 4 shows a second specific embodiment of an electromagnet according to the present invention for a solenoid valve.

DETAILED DESCRIPTION

(5) 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.

(6) 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.

(7) 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.

(8) 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 core 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.

(9) 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 to median longitudinal axis 28. Conical section 48 also extends at an angle 52 of approximately 30 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.

(10) 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.

(11) 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.

(12) 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.