Magnetostrictive sensor arrangement

Abstract

A magnetostrictive sensor arrangement for detecting the position of a mechanical component along a predetermined movement path, in particular the position of a piston in a hydraulic cylinder, comprising a ferromagnetic waveguide extending along the movement path, the near first end of which is connected to an electronic assembly for supplying a short electrical pulse, around which a radial magnetic field is formed upon supply of the pulse, and in which a mechanical torsional pulse propagates upon interaction of the radial magnetic field with the local magnetic field of a position magnet attached to the component, and the distant second end of which comprises a damping device for the torsional pulse, wherein a converter for converting the torsional pulse into an electrical pulse and a one-piece metal part are attached to the first end of the waveguide,which combines the functions of a reflector for the torsional pulse and a mechanical anchoring of the waveguide at its first end and an electrical contact for connecting the waveguide to the electronic assembly.

Description

[0001] The invention relates to a magnetostrictive sensor arrangement for detecting the position of a mechanical component along a predetermined movement path, in particular the position of a piston in a hydraulic cylinder or the position of a translationally moved machine part in a machine system or the like.

[0002] Such a sensor arrangement, as developed and manufactured by the applicant, has as its core a ferromagnetic waveguide running along the movement path, the near first end of which is connected to an electronic assembly for feeding in a short electrical pulse, around which a radial magnetic field is formed when the pulse is fed in and in which a mechanical torsional pulse propagates when the radial magnetic field interacts with the local magnetic field of a position magnet attached to the component, and the distant second end of which has a damping device for the torsional pulse.

[0003] At the first end of the waveguide, a so-called tape is attached as part of a converter for converting the torsional pulse into an electrical pulse. The waveguide is mechanically anchored there and electrically connected to an electronic module. The "tape," referred to below as the converter element, is surrounded by a coil in the converter system, which inductively converts the mechanical oscillations of the converter element into an electrical signal.

[0004] In the electronic assembly, the transit time between the moment the electrical pulse is fed into the waveguide and the reception of the latter signal is recorded, and from this the position of the aforementioned position magnet and thus of the mechanical component with respect to the waveguide is calculated.

[0005] The current state of the art provides the mechanical anchoring and electrical connection of the waveguide through several individual elements, each mounted separately and, in some designs, pressed and / or bonded to the end of the waveguide. These elements, collectively referred to as "signal converters," take up a relatively large amount of space and are complex to assemble.

[0006] The invention is based on the object of providing an improved magnetostrictive sensor arrangement which can be designed more compactly overall and whose signal converter requires less installation space and is simpler and thus more cost-effective to install.

[0007] This object is achieved by a magnetostrictive sensor arrangement having the features of claim 1. Appropriate developments of the inventive concept are the subject of the dependent claims.

[0008] The key element of the proposed sensor arrangement is a one-piece metal part ("armature") that combines the functions of a reflector for the torsional pulse, a mechanical anchor for the waveguide at its first end, and an electrical contact for connecting the waveguide to the electronic assembly. With its reflector function or reflection edge function, the metal part serves to amplify the amplitude of the torsional pulse at the position of the converter element (tape).

[0009] In the sensor arrangement proposed here, the so-called signal converter is characterized by geometric compactness and a design that allows for a production-optimized, uniform attachment of the actual converter (tape) and the mechanical fixation (anchor) using similar process steps. In a preferred embodiment of the invention, this is achieved by welding.

[0010] In a further embodiment of the invention, the metal part is configured as a through-hole plating for an SMD electronic assembly. This enables the use of standardized SMD assembly processes for connecting the waveguide to the signal reception and evaluation components of the sensor array.

[0011] In one design, the metal part is configured as a flat profile with multiple bends. Alternatively, the metal part is designed—in a particularly cost-effective manner—as a multiply bent wire part. A section of this multiply bent or bent metal part rests on a circuit board of the electronic assembly and is electrically connected there to a conductor section or component, while another section (particularly at the other end of the metal part) is firmly connected to the waveguide.

[0012] In a preferred embodiment of the invention, it is provided that the metal part is fixed in a plastic body placed on the circuit board of the electronic assembly in such a way that several profile or wire sections each lie in correspondingly extending recesses of the plastic body, so that the plastic body fixes the metal part in all spatial directions against displacements or rotations.

[0013] With regard to the function of the one-piece metal part as a reflector or reflection edge for the torsional pulse at the first end of the waveguide, it is particularly provided that the converter element for converting the torsional pulse into an electrical pulse is offset by a predetermined distance from the one-piece metal part toward the second, distant end of the waveguide. The distance is predetermined such that, taking into account the physical characteristics of the torsional pulses traveling through the waveguide, a maximum signal amplitude is achieved at the position of the converter.

[0014] Advantages and benefits of the invention will become apparent from the accompanying figures and the associated description of an embodiment. The figures show: Fig. 1 a perspective view of the first end of an embodiment of the magnetostrictive sensor arrangement with the signal converter system, Fig. 2 a schematic diagram of the proposed sensor arrangement in the form of a longitudinal section, Fig. 3 is a perspective view of an exemplary configuration of the one-piece metal part attached to the first end of the waveguide, Fig. 4 a perspective detail view to illustrate the fixation of the waveguide in the Fig. 1 to 3 shown embodiment And Fig. 5 is a perspective view of another exemplary configuration of the integral metal part attached to the first end of the waveguide.

[0015] Fig. Figure 1 is a sketch-like perspective view of the near end, i.e., the end adjacent to an electronic assembly (not shown here), of a magnetostrictive sensor arrangement 1 according to the invention. Its core is a ferromagnetic waveguide 2, shown only symbolically here, which runs from the near end in this embodiment in a straight line in two coaxial cladding tubes 3 and 4 to a distant second end (also not shown here). A return conductor 2a of the waveguide 2 runs parallel to the waveguide from its distant second end to the near first end; see the explanation of Fig. 2 below.

[0016] The near first end of the waveguide with its inner cladding tube 3 is fixed in a plastic coil former 5, which further carries a cylindrical coil 6 with its longitudinal axis perpendicular to the waveguide axis. Coil 6 is connected to a printed circuit board of the electronics assembly via two terminals 6a and 6b. A rod-shaped converter element 7, shown here as a separate part, is welded to the waveguide in the assembled state of the sensor arrangement such that it protrudes into coil 6.

[0017] A multiply angled metal flat profile 8 is also welded to the waveguide 1 at a predetermined distance from the position of the converter element 7, securing it in the coil body 5. It is therefore also referred to as an "armature plate." It also serves as a connecting conductor to the electronic assembly and (as mentioned above) as a mechanical reflector for the torsional wave propagating in the waveguide during a measurement process.

[0018] Fig. 2 shows in a schematic diagram in the form of a longitudinal section the functionally essential elements of the sensor arrangement 1 according to Fig. 1. Particularly visible are the converter element (tape) 7 extending into the coil 6 near the first end of the waveguide 2, a mechanical damping element 9 at the distant second end of the waveguide, as well as the return conductor 2a, which closes the electrical circuit for signal control of the waveguide, and finally a return conductor contact element 2b. The latter establishes electrical contact with corresponding components on the electronics board. Also shown is a position magnet 10, which is located on a component whose position is to be determined by the sensor arrangement.

[0019] Also shown schematically as an L-shaped element is the one-piece metal part 8 for securing and electrically connecting the waveguide, which also serves as a mechanical reflector. Also symbolically depicted is an electronics board 11 of the sensor array's electronic assembly.

[0020] Regarding the function of this arrangement, please refer to the explanations above.

[0021] Fig. 3 shows an exemplary geometric configuration of the metal part 8 from Fig. 1 and Fig. 2. Depending on the specific geometric design of the converter and the electronic board 11, various variations of this configuration are possible.

[0022] In the embodiment shown, the metal part 8 comprises a first rectilinear profile section 8a, a second profile section 8b bent at a right angle to the first profile section in its plane of extension, a third profile section 8c bent at a right angle perpendicular to the plane of extension of the second profile section, a fourth profile section 8d bent at a right angle to the third profile section in the plane of extension, a fifth profile section 8e bent at a right angle to the fourth profile section in the plane of extension of the third and fourth profile sections, and a sixth profile section 8f bent at a right angle to the fifth profile section perpendicular to the plane of extension of the first and second profile sections.

[0023] In the (sixth) profile section 8f touching the waveguide, a recess, such as a notch or a semicircular cutout, can be provided in which the first end of the waveguide lies during assembly of the sensor arrangement.

[0024] Fig. Figure 4 shows how the multiply bent metal flat profile (the "anchor plate") is positively fixed to the electronics board by means of a plastic body 12. The metal flat profile 8 is welded to the waveguide 2 on one side and to a contact element (not shown separately) on the electronics board 11 on the other.

[0025] The metal flat profile 8 is stably fixed in all three spatial directions by means of the multiple bends, which run in corresponding recesses of the plastic body 12, and thus equally fixes the waveguide 2, which is integrally connected to it, and connects it electrically to a contact partner on the electronic board 11.

[0026] Fig. 5 shows, as an alternative configuration to the metal flat profile 8 described above, a wire bent part 8' for fixing and electrically connecting the waveguide 2.

[0027] The bent wire part 8' is designed such that it comprises a first rectilinear wire section 8a', a second wire section 8b' bent at a right angle to the first wire section in its plane of extension, a third wire section 8c' bent at a right angle perpendicular to the plane of extension of the first and second wire sections, a fourth wire section 8d' bent at a right angle to the third wire section, a fifth wire section 8e' bent at a right angle to the fourth wire section, and a sixth wire section 8f' bent at a right angle to the plane of extension of the first and second wire sections and to the fifth wire section.

[0028] The implementation of the invention is not limited to the aspects highlighted above and the embodiment shown, but is also possible in a multitude of modifications that are within the scope of expert action.

Claims

[1] Magnetostrictive sensor arrangement for detecting the position of a mechanical component along a predetermined movement path, in particular the position of a piston in a hydraulic cylinder, with a ferromagnetic waveguide running along the movement path, the near first end of which is connected to an electronic assembly for feeding in a short electrical pulse, around which a radial magnetic field is formed when the pulse is fed in and in which a mechanical torsional pulse propagates upon interaction of the radial magnetic field with the local magnetic field of a position magnet attached to the component, and the distant second end of which has a damping device for the torsional pulse, wherein a converter for converting the torsional pulse into an electrical pulse and a one-piece metal part are attached to the first end of the waveguide,which combines the functions of a reflector for the torsional pulse and a mechanical anchoring of the waveguide at its first end and an electrical contact for connecting the waveguide to the electronic assembly. [2] Magnetostrictive sensor assembly according to claim 1, wherein the metal part is welded to the first end of the waveguide. [3] Magnetostrictive sensor arrangement according to claim 1 or 2, wherein the metal part is configured as a via for an SMD electronic assembly. [4] Magnetostrictive sensor arrangement according to one of the preceding claims, wherein the metal part is configured as a multiply bent flat profile, of which a first profile section rests on a circuit board of the electronic assembly and is conductively connected there to a conductive section and a further profile section is connected to the waveguide. [5] Magnetostrictive sensor arrangement according to claim 4, wherein the flat profile comprises a first rectilinear profile section, a second profile section bent at a right angle to the first in its plane of extension, a third profile section bent at a right angle perpendicular to the plane of extension of the first and second profile sections, a fourth profile section bent at a right angle to the third profile section in the plane of extension, a fifth profile section bent at a right angle to the fourth profile section in the plane of extension of the third and fourth profile sections, and a sixth profile section bent at a right angle to the fifth profile section perpendicular to the plane of extension of the first and second profile sections. [6] Magnetostrictive sensor arrangement according to one of the preceding claims, wherein the metal part is configured as a wire bent multiple times, in particular at right angles, of which a first wire section rests on a circuit board of the electronic assembly and is conductively connected there to a conductive section and a further wire section is connected to the waveguide. [7] Magnetostrictive sensor arrangement according to claim 6, wherein the wire comprises a first straight wire section, a second wire section bent at a right angle in its plane of extension relative to the second wire section, a third wire section bent at a right angle perpendicular to the plane of extension of the first and second wire sections, a fourth wire section bent at a right angle relative to the third wire section, a fifth wire section bent at a right angle relative to the fourth wire section and a sixth wire section bent at a right angle perpendicular to the plane of extension of the first and second wire sections and relative to the fifth wire section. [8] Magnetostrictive sensor arrangement according to one of claims 4 to 7, wherein the metal part is fixed in a plastic body placed on the circuit board of the electronic assembly in such a way that several profile or wire sections are each located in correspondingly extending recesses of the plastic body, so that the plastic body fixes the metal part in all spatial directions against displacements or rotations. [9] Magnetostrictive sensor arrangement according to one of the preceding claims, wherein the converter for converting the torsional pulse into an electrical pulse is offset by a predetermined distance from the one-piece metal part in the direction of the second, remote end of the waveguide. [10] Magnetostrictive sensor arrangement according to one of the preceding claims, wherein the converter for converting the torsional pulse into an electrical pulse comprises a further metal part fixedly attached to the waveguide, in particular welded thereto, and a coil into which the further metal part projects.

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