Method for manufacturing a magnetic pole core, magnetic pole core, electromagnetic actuator, and shock absorber

Abstract

The invention relates to a method for producing a magnetic pole core (1), having the following method steps: - providing a magnetic workpiece (10) having a first side (11) and a second side (12), wherein the first side (11) has a recess (15) which is directed toward the second side (12); - inserting at least two insert pieces (20) and at least one connecting medium (25) into the recess (15), wherein the at least one connecting medium (25) is arranged between the two insert pieces (20); and - connecting the at least two insert pieces (20) to one another in an integral bond and / or connecting the at least two insert pieces (20) to the workpiece (10) in an integral bond.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a magnetic pole core of an electromagnetic actuator with improved characteristics, a magnetic pole core manufactured according to the method, an electromagnetic actuator having a magnetic pole core, and a vibration damper having such an electromagnetic actuator. Background Technology

[0002] Magnetic pole cores are known in the prior art to employ various designs and are made of magnetic materials, particularly ferromagnetic metals. These pole cores are widely used in electromagnetic actuators for guiding magnetic flux, such as in damping valves used to control the damping characteristics of shock absorbers. The damping valve has an outlet opening between the inlet and outlet that can be more or less closed. Opening or closing this outlet opening throttles the flow and thus adjusts the damping characteristics of the shock absorber. If a "stiff" chassis is desired, the throttling effect is increased or the outlet opening is further closed, while in the case of a "soft" chassis, the outlet opening is further opened. Opening and closing the damping valve is achieved by an electromagnetic actuator system that supplies power to the valve body when the excitation coil is energized accordingly.

[0003] The damping valve should be configured to be "fail-safe" so that, for example, the motor vehicle can be safely operated using such a damper in the event of electromagnetic actuator failure.

[0004] In the prior art, various structural types of magnetic pole cores have been proposed for this purpose. In these cores, the magnetic pole core serves as a flux guiding component, while the components of the electromagnetic actuator are sealed and isolated from the medium in the vibration damper. This sealing is necessary to prevent contaminants from penetrating the components of the electromagnetic actuator and potentially interfering with the function of the electromagnetic actuator or vibration damper.

[0005] In the past, a flanged magnetic pole core was proposed, which was divided into a first segment and a second segment by an interruption. A non-magnetic insert was arranged in the interruption, connecting the first segment to the second segment. The insert was typically bonded integrally with both the first and second segments by brazing, sealing the interruption. This design resulted in a gas-tight and liquid-tight magnetic pole core, as has been proven in the past. However, it has been shown that the integral connection between the first segment, the insert, and the second segment is subject to wear due to internal stress and different coefficients of thermal expansion, and the sealing of the interruption cannot be permanently guaranteed. This can lead to premature failure of electromagnetic actuators, damping valves, and possibly even vibration dampers. Summary of the Invention

[0006] This invention is hereby proposed.

[0007] The object of this invention is to provide an improved method for manufacturing a magnetic pole core, a magnetic pole core, an improved electromagnetic actuator, and an improved vibration damper, which eliminates the known disadvantages of the prior art in a manner that satisfies the purpose and achieves the manufacture of a magnetic pole core with long-term stability, taking into account economic factors.

[0008] The method for manufacturing a magnetic pole core according to the present invention comprises the following steps:

[0009] A magnetic workpiece is provided having a first side and a second side, wherein the first side has a groove pointing toward the second side;

[0010] At least two inserts and at least one connecting medium are inserted into the recess, wherein at least one connecting medium is arranged between the two inserts; and

[0011] Connecting at least two inserts to each other in an integral manner and / or connecting at least two inserts to the workpiece in an integral manner by preferred melting of a connecting medium.

[0012] The method for manufacturing a magnetic pole core according to the present invention is based on the understanding that when the connecting medium melts, capillary forces distribute the molten connecting medium onto the contact surface between the workpiece and the insert, and the contact surface is completely wetted, thereby achieving an intermetallic connection between the insert and the workpiece. The material stress caused by the distribution of the force vector is partially compensated by at least two inserts inserted into the groove, and a magnetic pole core with a closed, integrally joined connector can be provided, eliminating the problems known in the prior art. It has also proven important that the flow path of the molten connecting medium is reduced.

[0013] Herein and in the following text, in conjunction with the present invention, a magnetic workpiece should be understood as a workpiece made of a soft magnetic material that can be easily magnetized in a magnetic field. Such materials are, for example, carbon steel, iron or so-called soft iron, silicon-added steel, nickel-iron alloys, nickel-cobalt alloys, etc.

[0014] Furthermore, a preferred improvement to this manufacturing method specifies that at least two inserts are made of non-magnetic materials, particularly stainless steel.

[0015] It has proven advantageous in performing this manufacturing method that at least one connecting medium comprises at least one insulating copper body inserted into the groove. Copper is excellently suited for manufacturing integrally bonded joints constituting closed brazed connections and possesses high elasticity due to its material properties, thereby compensating for stresses caused by the different thermal expansion of the insert and the workpiece. Furthermore, copper has low viscosity in the molten state, so the melt of the connecting medium completely wets the insert in the groove due to capillary forces, and a strong, integrally bonded brazed connection is achieved upon cooling. The at least one insulating copper body may preferably be a copper body adapted to the shape of the groove. For example, the copper body may be copper wire, a molded part, or a bulk material. The copper body may also be formed from a copper alloy. Alternatively, instead of copper as the connecting medium, another non-magnetic connecting medium comprising silver, brass, etc., and suitable for brazing, may be used. By definition, brazing is performed in a temperature range above 723 K.

[0016] An improved version of this manufacturing method specifies that the groove is machined into a first side of the workpiece by a cutting process. Preferably, the groove is formed into the first side as an annular groove with a U-shaped cross-section, having an inner side, a bottom side, and an outer side. The corresponding insert is cuboid in cross-section and can be adapted to the shape of the groove. The insert has a first surface and a second surface. When the groove is an annular groove, the corresponding insert can also be formed as an annular groove, wherein the first surface corresponds to the inner surface and the second surface corresponds to the outer surface.

[0017] According to another preferred embodiment of this manufacturing method, the first and / or second surfaces of at least one of the two inserts constitute a transition fit, thus allowing the insert to be pressed into the groove with moderate pressure. Here, it is advantageous that the insert has a transition fit only on the first or second side, while a clearance fit can be provided on the other side, taking into account the different thermal expansion of the materials used for the workpiece and the insert. When the desired temperature is reached, the connecting medium melts and can flow through a capillary gap of approximately the same size not only on the first side but also on the second side. Due to capillary forces, the melt flows and distributes therein.

[0018] According to another advantageous embodiment of this manufacturing method, the workpiece is positioned such that at least one of the inserts is pressed into the groove by gravity during the integral connection. Once the connecting medium liquefies upon reaching its melting temperature, at least one of the inserts can apply a compressive force to the liquefied connecting medium by gravity and expel the liquefied connecting medium between at least two inserts, thereby promoting the distribution of the molten connecting medium on the contact surface in the capillary gap. Here, the corresponding inserts sink, more precisely, preferably until the at least two inserts in the groove are abutted except for a thin layer of the molten connecting medium. As the workpiece cools, the connecting medium hardens and forms a closed integral connection not only between the workpiece and the inserts but also preferably between the at least two inserts.

[0019] According to a preferred improvement of this manufacturing method, the workpiece is heated and the connecting medium is liquefied until the connecting medium is nearly completely extruded between the inserts through capillary delivery in the groove and the two inserts are mated in the groove. Excess melt of the connecting medium may escape from the groove or settle in the recess on the bottom side. The near-constant thickness of the connecting medium after cooling, not only in the capillary gap but also between the inserts, prevents the formation of pores or cavities, which would impair the sealing of the integrally joined joint and increase internal stress.

[0020] An improvement to this manufacturing method specifies that material is removed from the first and / or second sides after the workpiece has cooled. Particularly preferred is that, after the workpiece has cooled, the first and / or second sides are re-machined by cutting methods such as turning, milling, or grinding.

[0021] Preferably, material is at least partially removed from the second side to expose the end side of one of the at least two inserts or the bottom side of the groove on the second side, thereby dividing the magnetic workpiece into a first segment and a second segment. After at least partially removing the second side and exposing at least one of the inserts, a groove is formed at the interruption between the first segment and the second segment, wherein the first segment and the second segment are integrally connected in the interruption by means of at least two inserts and a connecting medium.

[0022] Another aspect of the invention relates to a magnetic pole core manufactured using the manufacturing method according to the invention. The magnetic pole core is preferably divided into at least two segments by an interruption portion, wherein at least two non-magnetic inserts are arranged in the interruption portion, and the at least two segments are connected by these non-magnetic inserts using an integrally joined connector.

[0023] Alternatively, preferably, at least two non-magnetic inserts are made of stainless steel and connected by an integrally brazed connector, wherein copper can be used as the connection medium. The interruption is sealed airtightly and liquidtightly by the inserts and the integrally brazed connector, thereby preventing material transport from the first side to the second side through the interruption, and vice versa.

[0024] Another aspect of the invention relates to an electromagnetic actuator having such a magnetic pole core.

[0025] A third aspect of the invention relates to a vibration damper having such an electromagnetic actuator.

[0026] The fourth and final aspect of the invention relates to a motor vehicle having at least one such shock absorber. Attached Figure Description

[0027] The following describes in detail an embodiment of the magnetic pole core according to the present invention with reference to the accompanying drawings. In the drawings:

[0028] Figure 1 A cross-sectional view of a workpiece with a groove is shown, into which two inserts are pressed, and the two inserts are connected to the workpiece by means of an integrally joined connector brazed within the groove; and

[0029] Figure 2 A schematic diagram of the manufacturing method of the magnetic pole core is shown. Detailed Implementation

[0030] Hereinafter, components that are the same or have the same function will be represented by the same reference numerals. For clarity, not all components that are the same or have the same function will have reference numerals in each drawing.

[0031] Figure 1 Workpiece 10 is shown, which is configured to be approximately rotationally symmetrical about a longitudinal axis XX. Workpiece 10 has a sleeve section and a flange section, wherein the flange extends from the sleeve section perpendicular to the longitudinal axis XX.

[0032] The flange segment has a first side 11 and a second side 12, which are arranged at intervals along the longitudinal axis XX on opposite sides of the flange segment.

[0033] A U-shaped groove 15 is arranged in the flange section from the first side 11. The groove 15 is arranged in a ring around the longitudinal axis XX, preferably rotationally symmetrical about the longitudinal axis XX, and points towards the second side. The groove 15 has an inner side 15a, a bottom side 15b, and an outer side 15c, wherein the inner side 15a and the outer side 15c are arranged parallel to the longitudinal axis XX. The bottom side 15b may arch towards the second side 12 and may have a tapered countersunk hole or a spherical countersunk hole.

[0034] In addition, from Figure 1 As can be seen, the two inserts 20 are inserted into or pressed into the grooves 15. The respective inserts 20 are made of a non-magnetic material, such as stainless steel. The respective inserts 20 are annularly configured with two end sides 20b, a first surface 20a formed by the inner surface, and a second surface 20c formed by the outer surface.

[0035] The corresponding insert 20 can be inserted coaxially into the groove 15 with respect to the longitudinal axis XX, wherein the first surface 20a and the second surface 20c of the insert 20 are adapted to the inner side 15a and the outer side 15c. The inner side 15a of the groove 15 and the first surface 20a of the corresponding insert 20 can be configured as a transition fit, and its dimensions are within a tolerance range of ±0.05mm, more preferably ±0.025mm, and particularly more preferably ±0.015mm. The outer side 15c of the groove 15 and the second surface 20c of the corresponding insert 20 can also be configured as a transition fit, and its dimensions are within a tolerance range of ±0.025mm, more preferably ±0.015mm.

[0036] Figure 1 An additional magnetic pole core segment 40, made of magnetic material, is shown that can be connected to the workpiece 10. The magnetic pole core segment 40 is connected to the workpiece 10 via a non-magnetic sleeve 30, preferably made of stainless steel, wherein the non-magnetic sleeve 30 can also be connected by means of a connecting medium 25 via a brazed integral joint connector. Preferably, the workpiece 10 may have a tapered bevel 35 on the side facing the sleeve 30.

[0037] In the groove 15, two inserts 20 are integrally connected to the workpiece, wherein the integral connection is performed by brazing using a connecting medium 25 at a temperature above 723K, the connecting medium 25 comprising copper according to a preferred embodiment of the manufacturing method described in detail later.

[0038] Therefore, firstly, based on Figure 2 In method step 100, a workpiece 10 made of magnetic material is provided having a first side 11 and a second side 12.

[0039] Then, in method step 120, the groove 15 is preferably machined into the workpiece 10 on the first side 11 by turning or milling.

[0040] In subsequent method step 130, at least two inserts 20 and a connecting medium 25 are inserted into the recess 15, wherein the connecting medium 25 is preferably arranged between the two inserts 20 as at least one spacer. In this state, the last insert 20 inserted or pressed into the recess 15 may partially protrude from the recess 15.

[0041] In subsequent method step 140, the arrangement formed in method step 130 for integrally connecting the insert 20 to the workpiece 10 and integrally connecting the inserts 20 to each other is heated until the connecting medium melts.

[0042] When copper is used as the connecting medium 25, the arrangement is heated to at least the melting temperature of copper, which is approximately 1358 K. The copper liquefies and flows around the insert 20 in the groove 15 due to capillary forces, especially between the inner side 15a and the first side 20a and in the capillary gap between the outer side 15c and the second side 20c.

[0043] When heating the arrangement formed in method step 130, it is advantageous that the workpiece 10 is arranged such that the groove 15 is arranged vertically so that the insert 20 is pressed into the groove 15 by gravity. Therefore, Figure 1 The workpiece 10 shown is arranged such that the longitudinal axis XX is oriented in the vertical direction and the groove 15 points upward relative to the ground surface.

[0044] The arrangement from method step 130 is heated to a temperature higher than the melting temperature of the connecting medium 25 until the connecting medium 25 between the two inserts 20 is completely melted and until the two inserts 20 are mated on the remaining film layer of the connecting medium 25. In this heated state, pressure can also be used to press the two inserts 20 into the groove 15.

[0045] After cooling, both the first side 11 and the second side 12 can be machined. To form the magnetic pole core 1 according to the invention, material is removed from the second side 12 in method step 150 to expose the groove 15 or the insert 20 initially inserted into the groove 15 and to divide the workpiece into two regions 16, 18. Exposing the insert 20 is preferably done by milling or turning, thereby separating the workpiece 10 into two segments 16, 18 by an interruption created by the groove 15 and the insert 20 integrally arranged in the groove 15. The two segments 16, 18 are connected only by a non-magnetic material, namely the two inserts 20 and the connecting medium 25.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1 magnetic pole core

[0048] 10 workpieces

[0049] 11 First side

[0050] 12 Second side

[0051] 15 grooves

[0052] 15a inner side

[0053] 15b bottom side

[0054] 15c outer side

[0055] 16 sections

[0056] 17 Interruption Section

[0057] 18 sections

[0058] 20 inserts

[0059] The first surface of 20a20

[0060] 20b20 end side

[0061] The second surface of 20C20

[0062] 25 Connection Medium

[0063] 30 sleeve

[0064] 35 bevel

[0065] 40-pole core section

[0066] XX longitudinal axis

Claims

1. A method for manufacturing a magnetic pole core (1), comprising the following steps: A magnetic workpiece (10) having a first side (11) and a second side (12) is provided, wherein, The first side (11) has a groove (15) pointing toward the second side (12); At least two inserts (20) and at least one connecting medium (25) are inserted into the groove (15), wherein the at least one connecting medium (25) is arranged between the two inserts (20); and The at least two inserts (20) are connected to each other in an integral manner by heating the workpiece and liquefying the connecting medium (25) and / or the at least two inserts (20) are connected to the workpiece (10) in an integral manner.

2. The method according to claim 1, characterized in that, The at least two inserts (20) are made of non-magnetic material.

3. The method according to claim 1, characterized in that, The at least two inserts are made of stainless steel.

4. The method according to any one of claims 1 to 3, characterized in that, The connecting medium (25) includes at least one insulating copper body inserted into the groove (15).

5. The method according to any one of claims 1 to 3, characterized in that, At least one of the two inserts (20) has a transition fit on a first surface (20a) and / or a second surface (20c), the transition fit being adapted to the groove (15).

6. The method according to any one of claims 1 to 3, characterized in that, At least one of the two inserts (20) is inserted into the groove (15) by pressing.

7. The method according to any one of claims 1 to 3, characterized in that, When the workpiece (10) is integrally joined, it is positioned such that at least one of the two inserts (20) is pressed into the groove (15) by gravity.

8. The method according to any one of claims 1 to 3, characterized in that, The workpiece is heated and the connecting medium (25) is liquefied until the connecting medium is conveyed through the capillary in the groove (15) and melted between the inserts (20) and the at least two inserts (20) are approximately mated in the groove (15).

9. The method according to any one of claims 1 to 3, characterized in that, The material on the second side is removed by a cutting process to expose at least one of the two inserts (20).

10. A magnetic pole core (1) manufactured using the manufacturing method according to any one of the preceding claims.

11. The magnetic pole core according to claim 10, characterized in that, The interruption section (17) divides the magnetic pole core (1) into at least two segments (16, 18), and at least two non-magnetic inserts (20) are arranged in the interruption section (17), the at least two segments (16, 18) being interconnected by the non-magnetic inserts (20).

12. An electromagnetic actuator having a magnetic pole core (1) according to claim 10 or 11.

13. A shock absorber for a vehicle, comprising the electromagnetic actuator according to claim 12.

14. A vehicle having a shock absorber according to claim 13.

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