WO2020109121A1

WO2020109121A1 - Sensor assembly

Info

Publication number: WO2020109121A1
Application number: PCT/EP2019/082008
Authority: WO
Inventors: Ajoy Palit
Original assignee: Zf Friedrichshafen Ag
Priority date: 2018-11-28
Filing date: 2019-11-21
Publication date: 2020-06-04
Also published as: DE102018220458A1

Abstract

A sensor assembly comprises: - a flux element, which is mounted for movement along a trajectory; - a first, a second and a third flat coil, which are arranged adjacent to one another along a surface parallel to the trajectory; - and an evaluation device. The flat coils are shaped in such a way that the inductance of each flat coil is dependent on a position of the flux element along the trajectory. The evaluation device is designed to determine positions of the flux element with respect to inductances of the individual flat coils and to provide a position of the flux element on the basis of at least two corresponding determined positions.

Description

Sensor arrangement

The invention relates to an inductive position determination. In particular, the invention relates to the determination of a relative position of a movable element compared to a fixed element on board a motor vehicle.

A selector lever is provided on a motor vehicle for influencing a gear stage inserted in a transmission. The selector lever can be brought into different positions by the driver, the selector lever being able to be guided in a backdrop. The position of the selector lever along the backdrop is scanned and, if necessary, processed electronically. A control device can then control the transmission based on the driver's request expressed by the position of the selector lever.

A series of inductive coils can be attached to a console and a flow element can be attached to the selector lever to determine the position. The coils are excited to provide electromagnetic fields and inductances of the coils are determined. The flux element influences the inductance of a nearby coil, so that the position of the selector lever can be determined based on the specific inductances.

The invention has for its object to provide an improved device for indukti ven position determination. The invention solves this problem by means of a device with the features of the independent claim. Sub-claims ge preferred embodiments again.

According to a first aspect of the present invention, a sensor arrangement comprises a flow element that is movably attached along a trajectory; a first, a second and a third flat coil, which are arranged side by side in a surface parallel to the trajectory; and an evaluation device. The flat coils are shaped such that the inductance of each flat coil is dependent on a position of the flux element along the trajectory. The evaluation device is set up to determine positions of the flux element with respect to inductivities of the individual To determine flat coils and to provide a position of the flow element on the basis of at least two matching positions.

With the sensor arrangement, practically any number of positions of the flux element can be determined. It is not necessary to assign a flat coil to a position to be determined. A number and / or location of positions to be determined can be chosen freely and changed at any time. The sensor arrangement can be used flexibly for different applications and positions to be recognized can be calibrated if necessary. The sensor arrangement can be used, for example, for a selector lever to influence a gear stage inserted in a gear. The selector lever can, for example, be brought into five positions, which can be labeled S, D, N, P and R. Compared to a solution with flat coils assigned to the positions, a size of the area covered by flat coils can be greatly reduced. A robustness of the sensor arrangement can be increased and manufacturing costs can be reduced.

By determining the position of the flux element by means of three flat coils, redundancy can be created, which allows the sensor arrangement to operate even if one of the flat coils should fail, for example due to a short circuit or an interruption in the coil wire.

The trajectory is preferably a distance and the surface is preferably flat. A distance between the surface and the trajectory is more preferably constant. The trajectory can also run along a curve, which then preferably also follows the area at a constant distance.

The flat coils are preferably shaped such that the size of a region of a flat coil covered by the flux element in the surface is dependent on the position of the flux element along the trajectory. The area covered by the flow element can be determined on the basis of a projection of the flow element onto the surface. The entire area that the flow element can cover over its various positions in the surface is preferred by one of the flat surfaces. spools covered. The larger the area of a flat coil covered by the base element, the greater its influence on its inductance. By linking the covered area of a flat coil with the position, the inductance of the flat coil can be dependent on the position of the flux element, so that the position can be determined on the basis of the induction.

The trajectory usually extends between a start point and an end point. A width of the first and third flat coil transverse to the trajectory can decrease from the starting point, while a width of the second flat coil can increase from the starting point. As a result, the flat coils can be arranged in an improved compact manner. The first and third flat coils can be designed in such a way that their inductances correspond to one another regardless of the position of the flux element.

The second flat coil can lie in a direction transverse to the trajectory between the first and the third flat coil. This enables a particularly compact design of the flat coils to be achieved. Mutual interference between adjacent flat coils can also be reduced.

The flat coils preferably cover a rectangular area together. As a result, the flat coils can be of compact construction and can be easily arranged or installed together. The flow element can also have a rectangular shape, wherein widths of the flow element and the rectangular area can be the same and a length of the flow element in the direction of the trajectory is preferably less than the length of the rectangular area.

A flat coil usually comprises several turns that lie in the surface. An innermost turn can have the shape of a triangle and turns lying further outside can each have a constant distance from the next turn lying further inside. As a result, all turns except the innermost one can each have the shape of a trapezoid. One can also speak of a trapezoidal flat coil. In one embodiment, the innermost turns of the first and third flat coils each have the shape of a right-angled triangle and the innermost turn of the second flat coil has the shape of an equilateral triangle. The outer windings of the first and the third flat coil then essentially each have the shape of a right-angled trapezoid and the outer windings of the second flat coil have an essentially isosceles, symmetrical trapezoid.

Widths of the flat coils along the trajectory are preferably strictly monotonous. As a result, the inductances of the flat coils can also develop in a strictly monotonous manner via the position of the flux element along the trajectory. A clear determination of the position of the flux element on the basis of the inductance of a flat coil can thereby be made possible.

One of the flat coils can comprise several levels. The planes can be arranged along a distance direction of the trajectory from the surface. In practice, a flat coil can be formed as a printed coil in the form of a conductor track on a circuit board. In order to comprise several levels, coils can be formed on several layers of the board and electrically connected to one another to form a flat coil. The coils on the different layers usually have the same shape, surface and winding direction.

The flow element can comprise an electrically conductive element, which in particular extends parallel to the surface. The conductive element can reduce the inductance of a flat coil, in the electromagnetic field of which it is located, and thus act as a damping element. The flow element absorbs energy from the electromagnetic field and forms eddy currents in the electrically conductive material. In another embodiment, a flux element can be used that increases the inductance of a flat coil when it is in its electromagnetic field. The flux element is preferably made of an electrically poorly conductive, ferrimagnetic material such as ferrite or iron. The evaluation device can comprise a processing device which is set up to carry out a method described below in whole or in part. For this purpose, the processing device can comprise a programmable microcomputer or microcontroller and the method can be in the form of a computer program product with program code means. The computer program product can also be stored on a computer-readable data carrier. Features or advantages of the method can be transferred to the sensor arrangement or vice versa.

A second aspect of the invention relates to a method for determining the position of a flow element in a sensor arrangement described herein. The method comprises steps of determining inductances of the flat coils; determining positions of the flux element with respect to one of the determined inductances; and providing a position of the flow element based on at least two corresponding ones of the determined positions.

If the three determined positions correspond to one another, the position of the flow element can be determined on the basis of all three positions. Corresponding positions usually deviate slightly from one another due to imperfection in the determination. The provision of the position can include, for example, the formation of a minimum, a maximum, an average of the specific positions or the selection of a specific position that is assigned to a predetermined one of the three flat coils. If only two of the positions correspond to one another, the position of the flow element can be determined on the basis of these two specific positions.

In a general embodiment, N flat coils are provided in the area of the flux element, preferably N> 2 and N being more preferably odd. The position of the flux element can then be determined with respect to a majority of mutually corresponding positions, each of which is assigned to one of the flat coils. The sensor arrangement can generally continue to determine the position of the flux element even after the failure of N-2 flat coils. For reasons of space and If the probability of more than one flat coil failing at the same time is to be expected, it is proposed to choose N = 3.

In a further development of the method, a defective flat coil can be determined if the position determined on the basis of its inductance deviates from corresponding positions which have been determined on the basis of the other flat coils. A signal or a message indicating the defective flat coil can be provided. The defective flat coil can be excluded from further operation of the sensor arrangement. The sensor arrangement can continue to be operated at least as long as no further flat coils are determined to be defective.

The invention will now be described in more detail with reference to the accompanying figures, in which:

1 shows a system; and

2 shows a flow chart of a method

represents.

FIG. 1 shows in a top area a system 100 with a sensor arrangement 105, and in a bottom area a representation 110 of relationships on the sensor arrangement 105. The sensor arrangement 105 is set up to determine the position of a first element in relation to a second element. Before given the sensor arrangement 105 is set up to be used on board a motor vehicle to determine the position of a selector lever 115 which a driver can operate in order to influence the selection of an engaged gear stage in a gearbox in a drive train of the motor vehicle .

The sensor arrangement 105 comprises a first flat coil L1, a second flat coil L2 and a third flat coil L3, which lie side by side in a surface 120, which is preferably flat. In the present case, surface 120 extends in an xy plane that corresponds to the paper plane. A z-axis extends vertically towards the viewer. A flux element 125 is attached offset along the z-axis a predetermined trajectory 130 is displaceable. In the embodiment shown, the trajectory 130 coincides with the x-axis. Surface 120 is preferably rectangular and has edges that extend parallel to the x-axis or the y-axis. The flow element 125 is also rectangular in the illustrated embodiment and comprises edges that run in pairs parallel to edges of the surface 120.

The flat coils L1 -L3 can be mounted on a carrier 135 to form a separately manageable unit. The carrier 135 can be attached to a console and the selector lever 115 can be connected to the flow element 125, so that the flux element 125 is displaced with respect to the flat coils L1-L3 along the trajectory 130 when the selector lever 115 is moved with respect to the console. By way of example only, the selector lever 115 can assume five positions 140, which are denoted by S, D, N, P and R. Another assignment is also possible. A symbolic arrow on flow element 125 points to marks that indicate positions 140.

The carrier 130 can in particular comprise a circuit board and the flat coils L1 -L3 can be designed as conductor tracks on the circuit board. The circuit board can optionally comprise a plurality of layers, on each of which a section of a flat coil L1 -L3 can be formed as a conductor track, the sections of a flat coil L1 -L3 being electrically connected to one another. The flux element 125 may be made of a conductive material such as copper to act as a damping element for the inductances of the flat coils L1-L3.

The trajectory 130 extends in the illustrated embodiment from the position S (far left) to the position R (far right). The trajectory 130 is preferably so limited that the flow element 125 is in all positions 140 completely above (or below) the surface 120.

The flat coils L1 -L3 are shaped such that an area of each flat coil L1 -L3 covered by the flux element 125 depends on a position of the flux element 125. In the present case, the flat coils L1 and L3 are shaped so that they each the area covered by the flow element 125 is greatest when the flow element 125 is in position S and the covered area decreases strictly monotonously when the flow element 125 is moved in the direction of the position R. The flat coil L2 is shaped such that its area covered by the flux element 125 is the smallest when the flux element 125 is in the position S and the covered area increases strictly monotonously when the flux element 125 is shifted in the direction of the position R. becomes. The ge opposite arrangement of the flat coil L2 compared to the flat coils L1 and L3 is not absolutely necessary for the function of the sensor arrangement 105, but it can allow a particularly compact arrangement of the flat coils L1 -L3 on the surface 120.

The flat coils L1 -L3 preferably extend over the entire length of the surface 120 in the x direction. In the illustrated embodiment, the flat coils L1-L3 are each trapezoidal, with mutually parallel base sides of each trapezoid each extending in the y direction. The trapezoids of the flat coils L1 and L3 each carry two internal angles of 90 ° on the side facing away from the flat coil L2, one in the area of position S and one in the area of position R. The trapezoid of the second flat coil L2 has no right inner angle , but is symmetrical with respect to an axis parallel to the x-axis. Distances between the flat coils L1-L3 in the y direction are preferably constant along the x direction.

An evaluation device 145 is set up to determine inductances of the flat coils L1-L3. For this purpose, both ends of each of the flat coils L1 -L3 are preferably connected to the evaluation device 145, as indicated. To determine its inductance, a flat coil L1 -L3 can form part of an oscillating circuit, for example a parallel LC circuit, and its resonant frequency can be excited. The resonance frequency can be used as a measure of the inductance, which in turn depends on the area of the flat coil L1-L3 covered by the flux element 125. The size of the covered area is linked to the position 140 of the flow element 125, and thus to that of the selector lever 115, so that the position 140 of the selector lever 115 can be determined on the basis of the inductance of a flat coil L1 -L3. The evaluation device 145 is further preferably configured to determine the position 140 of the selector lever 115 or of the flow element 125 on the basis of positions 140, which were individually determined with respect to one of the flat coils L1 -L3. In particular, it can be determined whether two or more positions 140, which were each determined with respect to one of the flat coils L1 -L3, correspond to one another. If this is the case, the position 140 can be determined with respect to the mutually corresponding positions 140. The determined position 140 can be made available to the outside via an interface 150. The position provided can be continuously specified within a predetermined range or can discretely relate to one of the predetermined positions S, D, N, P or R. In addition, it can be determined whether one of the flat coils L1 -L3 has a defect.

The illustration 110 in the lower area of FIG. 1 shows qualitatively exemplary courses of inductances of the flat coils L1 -L3 as a function of different positions 140 of the flux element 125. A position 140 of the flux element 125 is plotted in the horizontal direction and an inductance is plotted in the vertical direction. Inductivities of the flat coils L1 and L3 are shown to be identical, although in practice they usually differ at least slightly from one another, even if the flat coils L1 and L3 are symmetrical to one another.

FIG. 2 shows a flowchart of a method 200 for determining the position 140 of the flow element 125 relative to an arrangement of coils L1 -L3 in a sensor arrangement 105 like that of FIG. 1. The method 200 can in particular be carried out using the evaluation device 145 and preferably starts in one Step 205.

In a step 210, an inductance of the flat coil L1 can be determined. Correspondingly, inductances of the flat coils L2 and L3 can be determined in steps 215 and 220. Steps 210-220 can be carried out sequentially, synchronized or concurrently with one another. For each particular inductance, a corresponding position 140 of the flux element 125 can then be determined in steps 230-240, for example on the basis of a table that maps inductances at positions 140 or on the basis of a known relationship that enables a functional determination of the Position 140 allowed on the basis of inductance.

In a step 250, the determined positions 140 can be compared with one another. If positions 140 of a plurality of flat coils L1 -L3 agree with one another, a position 140 of the flux element 125 can be determined on the basis of these determined positions 140 and provided in a step 255, for example via the interface 150.

For example, in the embodiment shown in FIG. 1, positions 140 determined with respect to the flat coils L1 and L2 essentially coincide and the position 140 determined with respect to the flat coil L3 deviates by more than a predetermined amount from the other two Positions 140 from, the position 140 of the flow element 125 can be determined with respect to the two matching positions 140. In this case, the flat coil L1 -L3, with respect to which a different position 140 was determined, can be determined as defective in a step 260. A flat coil L1-L3 determined as defective cannot be used to determine a position 140 in a subsequent run through the illustrated steps. The method 200 can be run through cyclically in order to determine the position 140 at predetermined time intervals.

System reference

Sensor arrangement

presentation

Selector lever

area

Flow element

Trajectory

carrier

position

Evaluation device

interface

method

begin

Determine inductance L1

Determine inductance L2

Determine inductance L3

Determine position according to L1

Determine position after L2

Determine position according to L3

Form majority decision

Provide position

determine defective flat coil

Claims

A sensor arrangement (105), the sensor arrangement (105) comprising: a flow element (125) which is movably attached along a trajectory (130); a first, a second and a third flat coil (L1 -L3), which are arranged side by side in a surface (135) parallel to the trajectory (130); the flat coils (L1-L3) being shaped such that the inductance of each flat coil (L1-L3) is dependent on a position (140) of the flux element (125) along the trajectory (130); and an evaluation device (145) which is set up to determine positions (140) of the flux element (125) with regard to inductivities of the individual flat coils (L1 -L3) and a position (140) of the flux element (125) on the basis of at least two to provide matching certain positions (140).

2. Sensor arrangement (105) according to claim 1, wherein the flat coils (L1 -L3) are shaped such that in each case the size of an area of a flat coil (L1-L3) covered by the flux element (120) in the surface (135) from the position (140) of the flow element (120) along the trajectory (130).

3. Sensor arrangement (105) according to claim 2, wherein the trajectory (130) extends between a start point (S) and an end point (R) and a width of the first and the third flat coil (L1 -L3) transverse to the trajectory ( 130) decreases from the starting point (S) and a width of the second flat coil (L1 -L3) increases from the starting point (S).

4. Sensor arrangement (105) according to claim 3, wherein the second flat coil (L1 -L3) in a direction transverse to the trajectory (130) between the first and the third flat coil (L1-L3).

5. Sensor arrangement (105) according to one of the preceding claims, wherein the flat coils (L1 -L3) together cover a rectangular surface (120).

6. Sensor arrangement (105) according to one of the preceding claims, wherein widths of the flat coils (L1 -L3) along the trajectory (130) in each case are strictly monotonous.

7. Sensor arrangement (105) according to one of the preceding claims, wherein one of the flat coils (L1 -L3) comprises several levels.

8. Sensor arrangement (105) according to one of the preceding claims, wherein the flow element (125) comprises an electrically conductive element which extends parallel to the surface (120).

9. A method for determining the position (140) of a flux element (125) in a sensor arrangement (105), the sensor arrangement (105) comprising a first, a second and a third flat coil (L1 -L3), which are arranged side by side in a surface (120 ) are arranged, and comprises a flux element (125), the flux element (125) being movably mounted along a trajectory (130) parallel to the surface (120), and the flat coils (L1-L3) being shaped such that the Induction of a flat coil (L1-L3) depends on the position (140) of the flow element (125) along the trajectory (130); the method comprising the following steps: determining inductances of the flat coils (L1-L3); Determining positions (140) of the flux element (125) with respect to one of the determined inductances; and providing a position (140) of the flow element (125) based on at least two mutually corresponding ones of the determined positions (140).

10. The method according to claim 9, wherein a defective flat coil (L1 -L3) is determined if the position (140) determined on the basis of its inductance deviates from corresponding positions (140) based on the other flat coils (L1 -L3) were determined.