EP1390959A2

EP1390959A2 - Magnet arrangement

Info

Publication number: EP1390959A2
Application number: EP02740320A
Authority: EP
Inventors: Klaus HÖFLING; Hans-Georg Schubert
Original assignee: Bosch Rexroth AG
Current assignee: Bosch Rexroth AG
Priority date: 2001-05-17
Filing date: 2002-05-08
Publication date: 2004-02-25
Anticipated expiration: 2022-05-08
Also published as: DE10220405A1; WO2002093592A3; US20040129318A1; US7093613B2; EP1390959B1; WO2002093592A2

Abstract

The invention relates to a magnet arrangement for an electromechanical drive comprising a cylindrical armature guided in a pole tube, whereby the position of the armature is transformed into an electric signal. A displacement sensor with a fixed and a mobile part is connected to the armature. One side of the armature is embodied in such a way that it transfers the movement of the armature. The other side of the armature is connected to the moveable part of the displacement sensor. The pole tube is provided with a closure part on the side of the displacement sensor. A pressure tube is guided in an outward direction through an axial recess of the closure part. The moveable part of the displacement sensor moves in the pressure tube. The pressure tube is enclosed by the fixed part of the displacement sensor. In order to prevent the displacement sensor from being damaged by vibrations, the fixed part of the displacement sensor is arranged in a recess of the closure part. Magnet arrangements of said variety are, preferably, used for electric re-positioning in liquid valves.

Description

description

magnet assembly

The invention relates to a magnet arrangement for an electromechanical drive, in particular for a fluidic valve, according to the preamble of claim 1.

Such a magnet arrangement is part of a hydraulic directional control valve from the publication "Novel, Cost-Effective Actuators for Proportional Valves in Fluid Technology", magazine "O + P Oil Hydraulics and Pneumatics" 43 (1999) No. 4, pages 252 to 258. In the housing of a directional valve, a control piston is axially displaceably mounted, which controls the size of the pressure medium flow flowing through the directional valve. In the axial extension of the control piston, a pole tube is screwed into the housing from both sides. A coil is slid over each pole tube. A cylindrical armature is guided in each of the two pole tubes and exerts a force deflecting the control piston when current is applied to the coil surrounding it. A displacement transducer is connected to one armature and converts the position of the armature into an electrical output signal which is a measure of the position of the armature. Since the control piston of the directional control valve is non-positively coupled to the armature, the electrical output signal of the displacement sensor is also a measure of the position of the control piston. The displacement sensor has a stationary part in the form of a coil arrangement and a movable part, the core. The core is held on a core carrier, which on the of the Spool facing away from the armature is held. The pole tube is closed on the side of the displacement transducer by a closure part which is provided with an axial recess. A pressure pipe is led out of the pole pipe through this recess. The closure part and the pressure pipe passed through this seal the armature space from the outside in a pressure-tight manner. The part of the pressure tube which projects beyond the closure part in the axial direction is concentrically enclosed by a coil arrangement which forms the fixed part of the displacement transducer. The coil arrangement is arranged in its own housing. This housing is held on the pole tube by a clamping bracket which engages in an outer annular groove of the closure part. In addition, toothing is provided which prevents the housing from rotating relative to the pole tube. The core of the displacement sensor moves in the area of the pressure tube enclosed by the coil arrangement. The housing of the stationary part of the displacement sensor lies against the coil and secures the coil in the axial direction. This type of attachment of the coil is more complex than the attachment of the coil by a nut, which engages in an external thread on the closure part, which is common in a pole tube without a displacement sensor, and increases the variety of parts. The arrangement of the displacement sensor in the axial extension of the pole tube makes the directional valve provided with the displacement sensor susceptible to vibrations, which in extreme cases can lead to the displacement of the displacement sensor.

The invention has for its object to provide a magnet arrangement of the type mentioned, in which the Risk of damage due to vibrations is significantly reduced.

This object is achieved by the feature characterized in claim 1. Since the entire displacement sensor is arranged within the closure part of the pole tube, the magnet arrangement has a very compact structure, in which the displacement sensor is also protected against mechanical damage. No separate housing is required for the stationary part of the displacement sensor. In addition, measures for fastening such a housing to the pole tube are omitted. The closure parts containing the fixed part of the displacement sensor can be manufactured and tested on their own.

Advantageous developments of the invention are characterized in the subclaims. They include structural details of the magnet arrangement, in particular those which allow a simple arrangement of the electronic components of a circuit arrangement for evaluating the output signals of the displacement transducer and a simple connection of external electrical lines. The subclaims also include constructive measures relating to the design of the closure part of the pole tube.

The invention is explained in more detail below with its further details using exemplary embodiments shown in the drawings. FIG. 1 shows a section through a magnet arrangement designed according to the invention, FIG. 2 shows the area of the closure part of the magnet arrangement shown in FIG. 1 in an enlarged view,

FIG. 3 shows a section through a further closure part with a closure part for a magnet arrangement according to the invention,

Figure 4 shows a section through a third closure part

End part for a magnet arrangement according to the invention, Figure 5 shows a section through that shown in Figure 4

Closing part,

6 shows a section through a fourth closure part for a magnet arrangement according to the invention and

7 shows a section through a further closure part with a closure part, the closure part and the closure part being connected to one another via a screw drive.

Identical components are provided with the same reference symbols in the figures.

FIG. 1 shows a section through a magnet arrangement 10 with a pole tube 11, an armature 12 guided in the pole tube 11 and a closure part 13. The pole tube 11 is screwed into a housing 14 of a fluidic valve, which is only shown schematically. A plunger 15 is formed on the armature 12 on the side facing the housing 14 and deflects a control piston of the valve, not shown here. A magnet coil 16, shown only schematically, surrounds the pole tube 11. The magnet coil 16 is between the housing 14 and a nut 17, which is screwed into an external thread 18 of the connector. engages closing part 13, held. A spring 19 is arranged between the armature 12 and the closure part 13. The spring 19 ensures a defined position of the armature 12 when the magnet coil 16 is not energized. The spring 19 can be omitted if a defined position of the armature 12 when the solenoid 16 is not energized is provided in another way. If the solenoid 16 is energized, the armature 12 is deflected accordingly. A core holder 21 provided with a core 20 is arranged on the side of the armature 12 facing the closure part 13. The core 20 forms the movable part of a displacement sensor. The displacement transducer converts the position of the armature 12 into an electrical signal, which is a measure of the position of the armature 12. The closure part 13 is provided with a recess 24 which is closed by a closure part 25. Details of the connection of the end part 25 with the closure part 13 are not shown in detail. Both parts can e.g. B. are glued together. In the end part 25, a plug 26 is integrated at the end. The end part 25 is provided with a recess 27 which merges into the recess 24 of the closure part 13. A coil arrangement consisting of two secondary coils 28a and 28b and a primary coil 28c surrounding them forms, together with a carrier 36, the stationary part of the displacement transducer. The carrier 36 with the coils 28a, 28b and 28c is arranged in the recess 24 of the closure part 13. The coils 28a and 28b and 28c are arranged concentrically with the core 20. Further details of the displacement sensor are described with reference to FIG. 2. FIG. 2 shows a section of the magnet arrangement 10 shown in FIG. 1 in an enlarged representation. Components that have already been described above are not described again in connection with FIG. 2. A pressure tube 29, which is closed on one side and is provided with a collar 30 at its open end, projects into the recess 24 of the closure part 13. The collar 30 is supported on an annular surface 31 of the closure part 13 facing the armature 12. A circumferential weld seam 32 ensures a pressure-tight connection between the collar 30 of the pressure tube 29 and the closure part 13. The weld seam 32 can be dispensed with if a pressure-tight connection is established in another way between the collar 30 and the closure part 13. Alternatively, it is possible to design the closure part and pressure pipe in one piece. The free end of the pole tube 11 is crimped into a first annular groove 33 of the closure part 13. A sealing ring 34 is arranged between the closure part 13 and the pole tube 11 in a further annular groove 35. So that the magnet coil 16 can be pushed onto the pole tube 11, the outer diameter dis of the external thread 18 is selected to be slightly smaller than the outer diameter du of the pole tube 11. Two winding ends, designated 37 and 38, are shown of the winding ends of the coils 28a, 28b and 28c arranged on the carrier 36. The winding ends 37, 38 are directly with in the simplest case

Pins 41, 42 of the plug 26 connected. It is also possible, as shown schematically in FIG. 2, to hold a circuit board 39 on the connecting pins 41, 42 of the plug 26, which is equipped with electrical components 44, 45 of an electrical evaluation circuit. In this case the winding ends 37, 38 are connected to the input of the evaluation circuit and the output of the evaluation circuit to the connection pins 41, 42.

FIG. 3 shows a further closure part 50 with a closure part 51. As shown in FIGS. 1 and 2, the circuit board 39 is held on the carrier 36 for the coils 28a, 28b and 28c of the stationary part of the displacement transducer. The carrier 36 is pushed over a pressure tube 53, which is in turn held on the closure part 50. The pressure pipe 53 is provided with a collar 54. The collar 54 is supported on the annular surface 31 of the closure part 50. The collar 54 is provided on the side facing the armature 12 with a recess 55 which is designed as a guide for the spring 19 shown in FIG. 1. The collar 54 is connected to the closure part 50 in a pressure-tight manner by a circumferential weld seam 32. The circuit board 39 is provided with soldering points 57 and 58, with which the winding ends 37 and 38 are connected. An electrical cable 60 is guided in the axial direction through the end part 51. In the passage area, the cable 60 is surrounded by a grommet 61. A tubular extension 62 which extends the end part 51 is formed on the end part 51 as an additional kink protection. The individual lines 63, 64 of the cable 60 are connected to further soldering points 65, 66 of the printed circuit board 39. In the simplest case, ie if no evaluation circuit is provided, the soldering points 57, 58 are connected to the soldering points 65, 66. In the exemplary embodiment shown in FIG. 3, the printed circuit board 39 is shown schematically by an electronic component 44, 45 Evaluation circuit connected, the input of which is connected to the soldering points 57, 58 and the output of which is connected to the soldering points 65, 66.

FIG. 4 shows a third closure part 67, in which a closure part designed as a plate 68 is screwed to the closure part 67. On the plate 68, the plug 26 is formed with the connecting pins 41, 42. The circuit board 39 is held mechanically on the connecting pins 41, 42. As shown in FIG. 2, the carrier 36 is held on the printed circuit board 39. From the plate 68, the connector pins

41, 42, the circuit board 39 and the support 36 unit formed is pushed over the pressure tube 53. The circuit board 39 with the schematically illustrated electrical components 44, 45 of an evaluation circuit is arranged in a recess 70 of the plate 68. The winding ends 37, 38 of the coils 28a, 28b, 28c are connected to the input of the evaluation circuit. The connection pins 41, 42 of the plug 26 are electrically connected to the output of the evaluation circuit. The plate 68 is held on the closure part 67 by screws distributed over the circumference, of which two screws 77, 78 are visible in FIG.

FIG. 5 shows a section along the line B-B shown in FIG. 4. In addition to screws 77 and 78, two further screws 79 and 80 are visible in this illustration. There are also two more in this cut

Pins 81, 82 and two further electronic components 84, 85 visible. FIG. 6 shows a further closure part 87. The end part of the closure part 87 is produced, as described below, by casting with plastic. The pressure pipe 53 projects into the recess 24 of the closure part 87 and is connected to it in a pressure-tight manner. The carrier 36 with the coils 28a, 28b, 28c is pushed over the pressure tube 53. The circuit board 39 is held on the carrier 36. The connection pins 41, 42 are held mechanically on the printed circuit board 39. This structure is inserted into a multi-part tool, shown only schematically, which consists of a base plate 90, two mold halves 91a, 91b and an insert 92. Together with the insert 92, the mold halves 91a, 91b enclose a space 94 which determines the later shape of the end part and the plug molded onto it. The mold halves 91a, 91b are divided along a plane running through the central axis of the closure part 87 in such a way that the closure part provided with the end part and the plug can be removed from the mold. Via a channel 95, which is only shown schematically, the space 94 and the recess 24 are filled with liquid plastic during casting. So that the plastic mass can be distributed uniformly in the mold, riser bores are provided in the tool and / or in the closure part 87 in the usual way. They are not shown in FIG. 6. Since the plastic also touches electrical circuit parts, it is necessary to use an electrically insulating plastic for the end part. To demold the closure part 87 provided with the end part and plug, after the plastic mass has solidified, the mold halves 91a and 91b are pulled apart laterally and the insert 92 is pulled out upwards. FIG. 7 shows a closure part 100, to which a closure part 101 is connected via a screw connection. Insofar as details are shown in FIG. 7 that have already been described in connection with previous figures, the same reference numerals are used in the following for the corresponding components as in the previous figures. The pressure tube 29 protrudes into the cylindrical recess 24 of the closure part 100. Its collar 30 is supported on the end face of the closure part 100 facing the armature of the magnet arrangement.

The recess 24 of the closure part 100 is provided with an internal thread 104 and the closure part 101 with a corresponding external thread 105. The internal thread 104 of the closure part 100 and the external thread 105 of the closure part 101 form a screw drive which rotates the closure part 101 relative to the closure part 100 in reshaped an axial movement between the two parts. The circuit board 39 is held on the end part 101. The carrier 36 with the coils 28a, 28b and 28c, which form the fixed part of the displacement sensor, are held on the printed circuit board 39. The region of the end part 101, in which the carrier 36 with the coils 28a to 28c is located, is arranged within the recess 24 of the closure part 100. The carrier 36 surrounds the pressure tube 29 concentrically. The distance between the pressure tube 29 and the carrier 36 is selected so that the carrier 36 can be moved with little play relative to the pressure tube 29. A lock nut 108, which is provided with an internal thread 107, is screwed onto the external thread 105 of the end part 101 and prevents the end part 101 from being inadvertently rotated during operation of the displacement sensor. prevented over the closure member 100. In order to secure the relative position of the end part 101 with respect to the closure part 100, the lock nut 108 is screwed against the closure part 100, its internal thread 107 being supported on the external thread 105 of the end part 101 and which with the

End face provided with reference numeral 110 on the closure part 100. The plug 26 with the connecting pins 41, 42 is molded onto the end of the closure part 101 facing away from the closure part 100. The position of the core 20, which forms the movable part of the displacement sensor, is shown with dashed lines. By turning the end part 101 relative to the closure part 100, the axial distance between the fixed and the movable part of the displacement sensor can be changed. The terms "fixed part" and "movable part" of the displacement transducer refer to the operation of the displacement transducer, in which the armature of the magnet arrangement moves the core 20 and the carrier 36 with the coils 28a to 28c is arranged stationary with respect to the valve housing. In order to adjust the displacement transducer, the core is held in a position that is stationary with respect to the valve housing and the end part 101 is rotated relative to the closure part 100 and thus with respect to the valve housing until the electrical output signal present at the connecting pins 41, 42 has assumed a desired value , As described above, this position is secured against unintentional rotation by tightening the lock nut 108.

The configuration of the closure part and the end part described with reference to FIG. 7 allows a zero point shift of the electrical output signal to mechanical niche way. With such a zero point shift z. B. Correct manufacturing-related tolerances with regard to the axial position of the stationary part of the displacement sensor. In addition, it is also possible to change the range of the electrical output signal by an axial adjustment of the fixed part of the displacement sensor relative to the closure part, so that, for. B. Instead of an output signal that moves between a negative and a positive maximum value, an electrical output signal results that moves between zero and a positive maximum value or between zero and a negative maximum value.

By linking the electrical output signal of the displacement transducer with predeterminable threshold values in the form of electrical signals, switching signals can be generated from the continuous output signal of the displacement transducer if necessary, which signal the reaching of the control piston of a control valve determined by the threshold values. The combination of the electrical signals can be both outside the closure part and inside the closure part, for. B. by the arrangement of additional electronic components on the circuit board 39. The switching signals are available in addition to the continuous output signal of the displacement transducer and can be processed independently in control and / or monitoring devices.

Claims

claims

1. Magnet arrangement for an electromechanical drive, in particular for a fluidic valve, with a cylindrical armature guided in a pole tube and with a magnet coil surrounding the pole tube and with a displacement transducer that converts the position of the armature into an electrical signal and that has a stationary and a movable part has, in which one side of the armature is designed to transmit the movement of the armature and the other side of the armature is connected to the movable part of the displacement sensor, the pole tube being provided with a closure part on the side of the displacement sensor, characterized in that the fixed part (28a to 28c, 36; 28a to 28c, 69) of the displacement sensor is arranged in a recess (24) of the closure part (13; 50; 67; 87; 100).

2. Magnet arrangement according to claim 1, characterized in that on the closure part (13; 50; 67; 87; 100) a closing part (25; 51; 68) is held.

3. Magnet arrangement according to claim 2, characterized in that electrical connecting lines (63, 64) of

Displacement sensor are guided through the end part (51).

4. Magnet arrangement according to claim 2, characterized in that a plug (26) is integrated in the end part (25; 68; 101).

5. Magnet arrangement according to claim 3 or claim 4, characterized in that the end part (25; 51; 68) is provided with a recess (27; 70) which in the recess (24) of the closure part (13; 50; 67) transforms.

6. Magnet arrangement according to claim 5, characterized in that a circuit board (39) is arranged in the recess (27; 70) of the end part (25; 51; 68; 101).

7. Magnet arrangement according to claim 6, characterized in that the printed circuit board (39) on the connecting pins (41, 42) of the plug (26) is held.

8. Magnet arrangement according to one of the preceding claims, characterized in that the movable part

(20) of the displacement sensor is guided in a pressure pipe (29; 53).

9. Magnet arrangement according to claim 8, characterized in that the pressure tube (29; 53) is provided with a collar (30; 54) which on an armature (12) facing ^¬ facing annular surface (31) of the closure part (13; 50; 67; 87; 100).

10. Magnet arrangement according to claim 9, characterized in that the collar (54) is designed as a guide (55) for a spring (19) arranged between the armature (12) and the closure part (50; 67; 87).

11. Magnet arrangement according to one of the preceding claims, characterized in that the closure part (13; 50; 67; 87; 100) is provided with an external thread (18) whose outside diameter (dis) is smaller than the outside diameter (du) of Pole tube (11).

12. Magnet arrangement according to one of claims 2 to 11, characterized in that the end part consists of plastic and is molded onto the closure part (87).

13. Magnet arrangement according to one of claims 2 to 11, characterized in that the fixed part (28 a to

28c, 36) of the displacement transducer is held on the end part (101) and that the end part (101) is adjustable in the axial direction relative to the closure part (100).

14. Magnet arrangement according to claim 13, characterized in that the end part (101) with the closure part

(100) is connected via a screw drive (104, 105).

15. Magnet arrangement according to claim 14, characterized in that the closure part (100) with an internal thread (104) and the end part (101) is provided with an external thread (105).

16. Magnet arrangement according to one of claims 13 to 15, characterized in that securing means (108) are provided which prevent accidental rotation of the end part

(101) against the closure part (100) prevent.

17. Magnet arrangement according to claim 16, characterized in that the end part (101) is provided with a lock nut (108), the internal thread (107) of which is supported on the external thread (105) of the end part (101) and the closure part (100) facing end face (110) is supported on this.