DRAW WIRE SENSOR

Abstract

A draw wire sensor which measures distance. The draw wire sensor comprising: a reel, shaft or axle; a wire wound up on the reel, shaft or axle; and a rotational sensor coupled to the reel, shaft or axle. A rotation angle of the sensor is transformed into an electrical signal and the rotational sensor utilizes the tunnel magnetoresistance effect.

Claims

1. A draw wire sensor for measuring linear distances, comprising: a reel, shaft or axle, a wire wound up on the reel, shaft or axle, and a rotational sensor coupled to the reel, shaft or axle, a rotation angle of the sensor is transformed into an electrical signal, and the rotational sensor utilizes the tunnel magnetoresistance effect.

2. The draw wire sensor of claim 1, wherein the rotational sensor comprises a stationary part including a tunnel magnetoresistance element and a rotating part including a magnet.

3. The draw wire sensor of claim 1, wherein a rotating part of the rotational sensor is coupled to the reel, shaft or axle.

4. The draw wire sensor of claim 1, wherein a total measurable distance and an extension of the wire corresponding with the total measurable distance correspond to a rotation of the rotating part of the rotational sensor by 360 degrees or less.

5. The draw wire sensor of claim 1, wherein the rotational sensor comprises a spring configured to maintain a tension of the wire.

6. The draw wire sensor of claims 2, wherein the stationary part of the rotational sensor is mounted on a printed circuit board.

7. The draw wire sensor of claims 2, wherein the rotational sensor is electrically coupled with a measurement unit for measuring the electrical resistance of the magnetoresistance element.

8. The draw wire sensor of claim 7, wherein the measurement unit comprises a Wheatstone bridge.

9. The draw wire sensor of claims 1, further comprising an electric power supply including a battery electrically connected or electrically connectable with the rotational sensor.

10. A mobile machine, including the draw wire sensor according to claim 1.

11. A sensor comprising: a rotating component; and a rotational sensor coupled to the rotating component, the rotational sensor comprising: a tunnel magnetoresistance element, and a rotating magnet.

12. The sensor of claim 11, wherein a rotation angle of the rotating magnet changes a resistance of the tunnel magnetoresistance element and the resistance of the tunnel magnetoresistance element is converted to an electrical signal.

13. The sensor of claim 12, wherein the tunnel magnetoresistance element comprises a reference element, a sensing element, and an isolating barrier positioned between the reference element and sensing element.

14. The sensor of claim 13, wherein the reference element is mounted to a circuit board and the rotating magnet rotates adjacent to a side of the sensing element opposite the circuit board.

15. The sensor of claim 13, wherein the rotation angle of the rotating magnet changes a magnetic field direction of the sensing element and the magnetic field direction of the sensing element changes a resistance of the isolating barrier.

16. The sensor of claim 13, wherein the reference element and the sensing element are magnetic and the isolating barrier comprises a metal oxide.

17. The sensor of claim 11, wherein a gear couples the rotating component and the rotational sensor such that the rotating component and the rotational sensor rotate at different speeds.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0026] FIG. 1 schematically shows a magnetoresisitve sensor and its operating principle.

[0027] FIG. 2 schematically shows a 3d view of a magnetoresistive sensor coupled to a spool on which the draw wire is wound up.

[0028] FIG. 3 schematically shows a housing with a sensor on a PCB.

[0029] FIG. 4 schematically shows a vehicle with a potential application for a draw wire sensor.

[0030] FIG. 5 schematically shows another view of the vehicle with a potential application for a draw wire sensor.

DETAILED DESCRIPTION

[0031] FIG. 1 schematically shows the structure of a magnetoresistive sensor 3. The sensor 3 comprises a stationary part or stationary portion 3a. Here, the stationary part 3a is fixed to a printed circuit board or PCB 6. The stationary part 3a comprises a magnetoresistive element 3b including a reference element 9a, a sensing element 9b and an isolating barrier 9c disposed in between the reference element 9a and the sensing element 9b. The reference element 9a and the sensing element 9b may be one or more of magnetic, ferromagnetic, or iron. The electrical resistance of the isolating barrier 9c strongly depends on the alignment of magnetic field directions of the reference element 9a and of the sensing element 9b. The magnetic field direction of the sensing element 9b is influenced by the magnetic field direction of an external rotatable magnet 3d. Hence, the electrical resistance of the sensor 3 reflects or is indicative of a rotation angle of the rotatable magnet 3d. Thus, the rotation angle of the rotatable magnet 3d may be measured by measuring the electrical resistance of the sensor 3.

[0032] As can be seen in FIG. 2, the rotatable magnet 3d is fixed to a shaft 10 that is coupled to a reel, shaft or axle 2. Here and in all of the following, recurring features shown in different figures are designated with the same reference signs. A draw wire 1 is wound up on the shaft/axle 2 and any extension of the draw wire 1 may be measured by a change of the electrical resistance of the magnetoresistance sensor 3. The shaft 2 is mechanically coupled to the shaft 10 by means of a gear 4 which is only represented symbolically in FIG. 2 and not shown in detail. The gear 4 may comprise a plurality of gearwheels, for example.

[0033] It is understood that in alternative embodiments not depicted here, a portion of the rotational sensor 3 may be directly mounted on or fixed to the shaft or axle 2. For example, in such an alternative embodiment either one of the magnet 3d or the magnetorisistive element 3b may be mounted on or fixed to the shaft or axle 2.

[0034] Returning to the embodiment depicted in the figures, a spiral spring 5 is provided which maintains a torque on the shaft 2. In this way, the spiral spring 5 maintains a longitudinal tension on the draw wire 1. In FIG. 2, the rotatable magnet 3d is shown in bold in a first position and as a dotted line in a second position, wherein the second position is rotated about the rotational axis of the shaft 10 by a few degrees with respect to the first position. The arrows 11 show the directions of movement of the draw wire 1 in case the draw wire 1 is extended or drawn back by the spiral spring 5.

[0035] FIG. 3 shows a housing 12 of a draw wire sensor with a printed circuit board 6, a shaft 2 on which the draw wire 1 is or may be wound, and a shaft 10 which forms part of the rotating part 3c of the sensor. The rotating part or rotating portion 3c of the sensor is positioned below the printed circuit board in FIG. 3. The stationary part 3a, a measurement unit 7 (see FIG. 1) and possibly further circuitry configured to carry out the resistance measurement are positioned on the printed circuit board 6.

[0036] Optionally, the draw wire sensor may include a second TMR sensor which is or may be mechanically coupled to the shaft 2 in order to create a redundant measuring system.

[0037] FIG. 4 shows a truck 15 with an extendable boom 13. The bidirectional arrow 14 shows the directions in which a draw wire sensor may measure linear movements while the boom is extended or retracted.

[0038] FIG. 5 shows the truck 15 in a top view with extendable support arms 16, 17, 18, 19 for stabilization of the truck, for example during stationary operation of the truck 15. The single support arms are extendable a certain distance which may be measurable by a draw wire sensor of the presently proposed type in the directions indicated by double arrows 20, 21, 22, 23.

[0039] FIGS. 1-5 show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example.

[0040] It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. Moreover, unless explicitly stated to the contrary, the terms “first,” “second,” “third,” and the like are not intended to denote any order, position, quantity, or importance, but rather are used merely as labels to distinguish one element from another. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.

[0041] As used herein, the term “approximately” is construed to mean plus or minus five percent of the range unless otherwise specified.

[0042] The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.