阅读说明：本技术 位移测量装置 (Displacement measuring device ) 是由 巴斯蒂安·安德烈亚斯·德赫尔里彭 马克·安东尼·曼奈斯 于 2018-06-01 设计创作，主要内容包括：位移测量装置(20)包括霍尔传感器(37)和安装在磁体壳体(38)中的磁体(35),磁体壳体(38)在容纳空间(47)中具有旋转自由度,调节装置以获得最佳的灵敏度包括旋转磁体壳体(36)。在调节之后,磁体壳体(36)固定在容纳空间(47)中。(The displacement measuring device (20) comprises a hall sensor (37) and a magnet (35) mounted in a magnet housing (38), the magnet housing (38) having a rotational degree of freedom in an accommodation space (47), and the adjusting means comprises a rotating magnet housing (36) for obtaining an optimal sensitivity. After adjustment, the magnet housing (36) is fixed in the accommodation space (47).)

1. A method of manufacturing a displacement measuring device (20), characterized in that the method comprises the steps of:

-providing a plate-like support base (21) comprising two supports (22, 23) separated by a gap (24), the support base (21) being deformable such that the two supports (22, 23) are movable relative to each other;

-arranging a first circular accommodation space (47) in a first one (22) of said two supports, adjacent to said gap (24), perpendicular to said plate-like support base;

-arranging a second circular accommodation space (48) in a second one (23) of said two supports, adjacent to said gap (24), perpendicular to said plate-like support base, wherein a virtual line connecting said first accommodation space (47) and said second accommodation space (48) defines a sensor orientation direction (X);

providing a sensor system (27, 28) comprising a sensor unit (28) and a reference unit (27),

wherein

-the sensor unit (28) comprises a sensor housing (38) and a sensing element (37) mounted in the sensor housing, and

-the reference unit (27) comprises a reference housing (36) and a sensor reference element (35) eccentrically mounted in the reference housing;

-inserting the reference unit (27) into the first housing space (47), with an insertion displacement direction (Z) perpendicular to the sensor orientation direction (X) and to the plate-like support base;

-placing the sensor unit (28) into the second housing space (48) perpendicular to the sensor orientation direction (X) and perpendicular to an insertion displacement direction (Z) of the plate-like support base;

-adjusting the positioning of the sensor system (27, 28) by rotation of the reference housing (36) about its respective axis of rotation in the first circular accommodation space (47);

-fixing the reference unit (27) and the sensor unit (28) in their respective accommodation spaces.

2. The method of claim 1, wherein the sensing element comprises a hall sensor, and wherein the reference element comprises a magnet.

3. Method according to any one of the preceding claims, characterized in that the first and second accommodation spaces (47, 48) open towards the gap (24).

4. Method according to any of the preceding claims, characterized in that the reference unit (27) and/or the sensor unit (28) protrude from the respective support (22, 23) into the gap (24).

5. Method according to any one of the preceding claims, characterized in that the step of adjusting the positioning of the sensor system (27, 28) comprises the step of radially moving the reference element with respect to the reference housing.

6. The method of claim 5, wherein the step of radially moving the reference element comprises the step of axially inserting a tapered tool into the reference housing.

7. The method according to any of the preceding claims, characterized in that the step of adjusting the positioning of the sensor system (27, 28) is performed while monitoring an output signal of the sensor unit (28), and wherein the rotational position of the reference unit (27) is set such that the output signal of the sensor unit (28) has a predetermined target value.

8. A displacement measuring device (20) with a sensor system (27, 28), characterized in that the measuring device comprises:

-a plate-like support base (21) comprising two supports (22, 23) separated by a gap (24), the support base (21) being deformable such that the two supports (22, 23) are movable relative to each other;

-wherein a first one (22) of the two supports has a first circular accommodation space (47) adjacent to the gap (24) perpendicular to the plate-like support base;

-wherein a second support (23) of said two supports has a second circular housing space (48) adjacent to said gap (24) perpendicular to said plate-like support base, wherein a virtual line connecting said first housing space (47) and second housing space (48) defines a sensor orientation direction (X);

-wherein the sensor system (27, 28) comprises a sensor unit (28) and a reference unit (27), the sensor unit (28) comprising a sensor housing (38) and a sensing element (37) mounted in the sensor housing, and the reference unit (27) comprising

A reference housing (36) and a sensor reference element (35) eccentrically mounted within the reference housing;

-wherein the reference unit (27) is arranged in the first accommodation space (47);

-wherein the sensor unit (28) is arranged in the second accommodation space (48);

-wherein the first housing space (47) and the reference unit (27) are shaped such that the reference unit (27) has a rotational degree of freedom within the respective housing space (47) about a rotational axis (Z) perpendicular to the sensor orientation direction (X).

9. The displacement measuring device of claim 8, wherein the sensing element comprises a hall sensor and the reference element comprises a magnet.

10. Displacement measuring device according to any one of the preceding claims 8-9, characterised in that the first receiving space (47) and the second receiving space (48) are open towards the gap (24).

11. Displacement measuring device according to any one of the preceding claims 8-10, characterised in that the reference unit (27) and/or the sensor unit (28) protrude from the respective support (22, 23) into the gap (24).

12. A force measuring device comprising a displacement measuring device (20) according to any of claims 8-11, which responds to an external force by a displacement of the two supports (22, 23) relative to each other.

13. An adjustment device for adjusting the position of a housing (36) of a unit (27) of a displacement measuring device (20) according to any one of claims 8-11, characterized by comprising a support (61) having a top surface (62), and a tool (63) extending upright from the top surface (62) and having a profile adapted to engage the housing (36);

a motor (66) for rotating the tool (63);

a control device (65) that controls the motor (66);

an interface (64) coupled to the control device (65) and adapted to receive an output signal from the displacement measuring device;

wherein the control device (65) is adapted to monitor a measurement output signal received from the displacement measuring device and to control the motor (66) such that the tool (63) is brought into a rotational position, wherein in the rotational position the measurement output signal received from the displacement measuring device has a predetermined desired value.

14. A displacement measuring device (20) comprising a plate-like support base (21) holding a hall sensor (37) and a magnet (35) mounted in a magnet housing (36), the magnet housing (36) having a rotational degree of freedom with respect to the support base (21) about an axis of rotation perpendicular to the support base.

15. A method for adjusting the displacement measuring device (20) of claim 14, the method comprising the step of rotating the magnet housing (36) relative to the support base (21).

16. A human-driven vehicle having an auxiliary electric motor for providing auxiliary driving force in relation to driving force provided by a human driver, characterized in that the vehicle comprises a force measuring system for measuring driving force provided by the human driver, the force measuring system comprising a displacement measuring device according to any of claims 8-11 or a force measuring device according to claim 12.

17. The vehicle of claim 16, wherein the vehicle is a bicycle.

Technical Field

The present invention generally relates to force measuring devices.

To measure the force, various measurement techniques may be used. Forces tend to cause deformation of the object on which the force is applied, and one measurement technique is to measure the deformation of the object in question. The deformation of an adjacent or solid object can be measured by, for example, a strain gauge. Strain gauges actually measure local changes in the length of an object (stretching or shrinking). If the object comprises two parts with a gap in between, the deformation may result in a displacement of the two object parts relative to each other, and the mutual displacement of the two object parts may be measured in proportion to the applied force. On the other hand, it may also be necessary to measure the relative displacement of two different objects.

The invention relates in particular to a measuring device based on the principle of measuring displacement.

Background

In various technical fields, it is desirable to be able to measure forces. One particular field is that of bicycles (or other human powered vehicles) in which it is necessary to measure the pedaling force exerted by a cyclist. For background purposes reference is made to EP-1863700.

The measured signal can be used, for example, to calculate the energy consumed by the cyclist, but also as an input signal for the control device of the electric backup motor to assist the cyclist. In the following, the invention will be explained with particular reference to an example of an electrically assisted bicycle, but it should be noted that this explanation should not be construed as limiting the invention or its applicability.

Fig. 1 schematically shows the design of a displacement measuring device 10, which comprises a plate-shaped support base 1, typically, though not necessarily, made of a solid metal plate of sufficient thickness, typically aluminium, typically in the range of 3-10 mm. The support base 1 comprises at least one gap 4 between the two supports 2 and 3. The width direction of the gap 4 will be indicated as the X direction, and the longitudinal direction of the gap 4 will be indicated as the Y direction. On opposite sides of the gap 4, two connecting legs 5 and 6 extend in the X-direction, connecting the two support parts 2 and 3. The design in fig. 1 is symmetrical and the gap 4 is the central part of a substantially H-shaped gap.

The support base 1 includes a mounting hole for mounting the displacement measuring device 10 to an object such as a bicycle. For simplicity, these mounting holes are not shown. In some embodiments, the support base 1 is formed as part of a bicycle carrying frame.

If a force is applied in the X-direction, in particular the connecting legs 5 and 6 of the support base 1 have sufficient stiffness to substantially prevent relative movement of the two support parts 2 and 3 in the X-direction. It will be apparent to those skilled in the art that the connecting legs 5 and 6 are less stiff in the Y direction, so that in response to a force applied in the Y direction, in particular the two support parts 2 and 3 will undergo some displacement relative to each other in the Y direction. Also, in response to a force applied in the Z direction perpendicular to the position of the support base 1, or in response to a torque, the two support parts 2 and 3 will undergo some displacement relative to each other in the Y direction and/or the Z direction. In contrast, the two support portions 2 and 3 have only freedom of displacement in the Y direction and the Z direction. Obviously, the ratio between force and displacement will depend on the stiffness, and the stiffness in the X, Y and Z directions will depend on, among other things, the shape of the parts, on the choice of material of the support base foundation, more specifically, on the material of its connecting legs 5 and 6, and on the thickness of the material.

The displacement measuring device 10 further comprises a sensor unit 8 and an input/output terminal 9 for providing an output signal of the sensor unit 8. The sensor unit 8 is mounted in one support 3 facing the opposite support 2 close to the gap 4. Reference numeral 7 denotes a reference unit installed in the opposite support 2 near the gap 4. A virtual line connecting the reference unit 7 and the sensor unit 8 will be represented as a sensor facing direction and is substantially equal to the X direction.

The sensor unit 8 comprises the actual sensitive element mounted in the housing, while the reference unit 7 comprises the actual reference element mounted in the housing. The sensitive element (not shown for simplicity) is sensitive to the displacement of the reference element. In a preferred embodiment, the sensing element is a hall sensor and the reference element is a magnet. Since hall sensors and their operation are generally known and commercially available, a more detailed description is omitted here.

The challenge with displacement measuring devices 10 is manufacturing. In order to be able to measure small displacements accurately, the X-distance between the hall sensor and the magnet should be small. For this reason, the gap 4 is usually manufactured as a narrow gap with a width of less than 1mm, but requires a complicated and expensive technique. For placing the components 7 and 8, grooves are machined on the main surface of the support base 1.

Furthermore, the hall sensor and the magnet should be positioned very accurately with respect to each other. Typically, the magnet unit 7 is attached first, and then the hall element 8 is positioned. The support base 1 allows some linear displacement of the hall element 8 in a direction perpendicular to the X-direction. The positioning is performed while the monitored output signal is obtained, and the positioning is considered optimal if the output signal has a certain target value. The hall element 8 is then fixed, typically with a fast acting glue. However, this is cumbersome and the accuracy obtained is not optimal.

It has also been proposed to mount the hall sensors and magnets first together on a sub-frame which is then attached to the support base 1, but this presents problems with tolerances for mounting the hall sensors and magnets on the sub-frame and attaching the sub-frame to the support base 1.

Document US-2008/0034896 discloses a measuring device with a complex design, comprising a curved rod and a cylindrical sleeve. The curved rod has two curved legs extending parallel to each other in the longitudinal direction and meeting each other in a base part. In the base part, a longitudinal magnet chamber is arranged between the two legs. The sleeve has a radial bore. First, an elongated magnet is axially introduced and fixed in a magnet chamber. The sleeve is then placed around the rod and welded to the rod. Finally, a sensor unit is arranged in the radial hole of the sleeve, carrying a hall sensor, which will be located between the two legs of the rod, close to the protruding end of the elongated magnet. The sensor unit is rotated about its axis of rotation extending radially relative to the bending rod to find a position where the output signal is zero, and then fixed.

A disadvantage of this known measuring device is the need to rotate the sensor unit, which requires the transmission of the measuring signal to the outside world. More importantly, however, the disadvantage is that the two receiving holes for the functional elements of the measuring device (i.e. the magnet and the sensor) are formed in separate parts, namely the rod and the sleeve, which are later connected by welding. In addition to being expensive, this makes it difficult to achieve high accuracy in the relative positioning between the magnet and the sensor.

Disclosure of Invention

It is an object of the present invention to provide a design and manufacturing method of a displacement measuring device 10 which allows an easier and more cost-effective assembly, allows positioning accuracy to be achieved in an easier and more convenient manner, and in particular allows simpler and more accurate adjustability.

According to the first aspect of the invention, the magnet is included in the rotatable magnet unit, the hall sensor unit 8 is first attached, and then the positioning of the magnet unit 7 is adjusted and fixed. The positioning of the magnet unit 7 is easier to manipulate in view of the wires 9 connected to the hall sensor unit 8.

According to the second aspect of the present invention, the receiving holes for the magnet unit and the sensor unit, respectively, in the plate-shaped support base are circular receiving holes whose axial direction is perpendicular to the Z direction of the X direction and the Y direction, i.e., perpendicular to the plane of the plate-shaped support base. These holes can be easily and accurately formed by drilling or punching or the like in the plate-like support base 1, with the drilling direction or punching direction directed in the Z direction perpendicular to the X direction and the Y direction. Making the holes in this way is relatively easy and accurate in terms of diameter, orientation and positioning. It should be noted that two holes are formed in the two supports which are integral parts of the same plate, so their relative positioning is and remains accurate. The hall sensor units 8 are placed in their respective holes, using insertion in the Z direction, and fixed by glue or the like. The magnet units 7 are placed in their respective holes using insertion in the Z-direction. The magnets in the magnet unit 7 are positioned eccentrically, close to the surface. When the magnet unit 7 is inserted, the unit is positioned substantially in the correct orientation with low precision. Subsequently, the magnet unit 7 is rotated about the Z axis, causing displacement in the Y direction at the surface portion facing the hall sensor unit 8. At the same time, the output signal of the hall sensor unit 8 is monitored and the angular orientation of the magnet unit 7 is adjusted such that the output signal has a certain target value within a certain tolerance. Since the magnet units 7 are already retained within their respective apertures, it is relatively easy to change the angular orientation. In practice, the adjustment process may be interrupted and then continued or improved. Any manufacturing tolerances of the holes and any tolerances in the positioning of the hall sensor unit 8 can thus be compensated for, but they are already smaller compared to the prior art design of US-2008/0034896.

According to the third aspect of the invention, the central axis of the receiving hole is located at a smaller distance from the edge of the gap 4 than the radius of the hole. Therefore, each accommodation hole opens into the gap, and the magnet unit 7 and the sensor unit 8 protrude into the gap. Thus, the mutual distance between the magnet unit 7 and the sensor unit 8 can be much smaller than the gap width. Conversely, the gap 4 may have a considerable width, e.g. 3-5mm, and the accuracy of the width of the gap 4 is less important, so that the gap may be manufactured more easily and cost-effectively with conventional techniques, such as milling or punching.

The receiving hole may be formed before the gap is cut. Also, the receiving hole may be cut in the same process as the gap is cut.

Drawings

These and other aspects, features and advantages of the present invention will be further explained by the following description of one or more preferred embodiments with reference to the drawings, in which like reference numerals indicate like or similar parts, and in which:

fig. 1 schematically shows a displacement measuring device;

FIG. 2 schematically illustrates an embodiment of a displacement measuring device according to the present invention;

FIG. 3 schematically shows a detail of a displacement measuring device on a larger scale;

FIGS. 4A-4C show details of possible shapes of the magnet housing and corresponding receiving holes;

fig. 5A and 5B are schematic perspective views of embodiments of a magnet unit;

FIG. 6 is a schematic block diagram of an apparatus for adjusting a magnet housing;

figures 7A-7C illustrate possible radial adjustment of the position of the magnets in the magnet housing.

Detailed Description

Fig. 2 schematically shows an embodiment of a displacement measuring device 20 according to the invention, which is suitable for use as a force measuring device in an electric power assisted bicycle. Reference numerals in the range 21-29 indicate the same or similar parts as the parts in the range 1-9 of the reference numerals discussed above with reference to fig. 1. Reference numeral 33 denotes mounting holes for passing screws for attaching one support portion 23 to the frame of such a bicycle. Reference numeral 32 denotes a mounting hole for connecting the opposite support portion 22 to the shaft of the driven wheel. If the rider pushes on the pedals, the driving force in the drive train (typically a chain) will exert a force on the driven wheel, thereby slightly displacing the axle of the driven wheel (typically the rear wheel) relative to the bicycle frame, thereby displacing the support portions 22 and 23 relative to each other, mainly in a direction perpendicular to the X-direction, i.e. in the direction of the virtual line connecting the magnet and the sensor.

Fig. 3 schematically shows a detail of the displacement measuring device 20 on a larger scale. Reference numeral 42 denotes an edge of the plate-like support portion 22. Reference numeral 43 denotes an edge of the plate-like support portion 23. Reference numeral 47 denotes a circular accommodation hole for accommodating the magnet unit 27. Reference numeral 48 denotes a circular accommodation hole for accommodating the hall sensor unit 28. The axial direction of the bore is in the Z-direction, i.e. perpendicular to the plane of the drawing. On the left-hand side of the dashed line, the magnet unit 27 with the magnet 35 in the magnet housing 36 is shown, and the sensor unit 28 with the hall sensor 37 in the sensor housing 38 is shown, while on the right-hand side of the dashed line the respective accommodation holes 47, 48 are shown empty. It can be seen that the receiving holes 47, 48 are open towards the gap 24 and that the magnet unit 27 and the hall sensor unit 28 project into the gap 24 such that their mutual distance is smaller than the width of the gap 24. The receiving bores 47, 48 may have mutually the same diameter, but this is not critical.

It is convenient to insert the magnet unit 27 and the sensor unit 28 into the respective holes 47 and 48 by linear axial movement in the Z-direction.

At least one of the sensor parts 27, 28 is held in the respective receiving hole 47, 48 with a rotational degree of freedom. In any case, this will apply to the magnet units 27 in the respective receiving holes 47, but equally to the hall sensor units 28.

In order to maintain rotational freedom, the cells and holes do not have to have rotational symmetry. Fig. 4A shows that the circular unit 44 has a rotational degree of freedom in the square hole 45. Fig. 4B shows that the square cells 44 have rotational freedom in the circular holes 45. Furthermore, a rotational degree of freedom in the sense of the present invention does not require a rotational degree of freedom exceeding 360 °. A 20 ° degree of freedom of rotation is usually more than sufficient for the required adjustment purposes. This in turn means that a portion of the unit projects into the gap 24 through the "mouth" of the receiving hole, even without needing to fit within the receiving hole as shown in exaggerated fashion in fig. 4C.

Fig. 5A is a schematic perspective view of an embodiment of a magnet unit 27 according to the present invention. The magnet unit 27 comprises a magnet housing 36, the magnet housing 36 having a cylindrical cross-section in this example. The magnet housing 36 may be made of a suitable plastic material or any other suitable material. For simplicity, the magnets disposed in the magnet housing 36 are not shown.

In one embodiment, magnet housing 36 has a flange 51 at one end, preferably a tapered flange as shown. The corresponding receiving hole 47 may be provided with a similar tapered inlet portion. These tapered portions cooperate to provide an axial stop when the magnet housing 36 is inserted into its respective receiving hole 47, thereby ensuring correct axial positioning. It should be clear that this "stop function" can also be realized in different shapes.

As shown in the schematic perspective view of fig. 5B, in one end face 52, which in this case is the end face associated with the tapered flange 51, the profiled recess 53 allows engagement of a tool that rotates the magnet housing 36. Preferably a groove having a 6-point star-shaped profile ("quincunx"). The opposite end face is indicated by reference numeral 56.

Fig. 6 is a schematic block diagram of an apparatus 60 for inserting and adjusting magnet housing 36. The device 60 comprises a support 61 having a top surface 62, and a tool 63 extending upright from the top surface 62, the tool 63 having a profile matching the profile of the recess 53. The worker places the magnet housing 36 (already provided with a magnet) on the tool 63 so that the tool 63 and the recess 53 engage with each other. Then, the worker takes up the support base 1 of the measuring device 10, aligns the accommodation hole 47 with the magnet housing 36, and gently pushes downward so that the magnet housing 36 enters the accommodation hole 47 until the flange 51 hits the support 61. Alternatively, the worker may first push the magnet housing 36 into the accommodation hole 47 and then engage the recess 53 with the tool 63. The worker preferably visually ensures that the angular orientation of the magnet housing 36 is approximately to the right, but a tolerance of approximately 1mm (measured on the circumference of the magnet housing 36) is acceptable. The input/output terminal 29 of the measuring device 10 is connected to an interface 64 of the device 60, which interface is connected to a control device 65, which control device 65 controls a motor 66 for rotating the tool 63. While continuously receiving the measurement output signal from the hall sensor, the control device 65 adjusts the rotational position of the magnet housing 36 such that the value of the measurement output signal from the hall sensor is equal to a predetermined desired value within a predetermined accuracy range, typically better than 0.1%. This ensures that the measurement signal provided as output will correspond very accurately to some mechanical deformation of the support substrate 21, given similar measurement behavior of the different measurement devices.

After this position has been reached, the control means 65 holds the tool 63 stationary and provides a signal to the worker who will then apply a quick-acting glue to secure the magnet housing 36 in place. In a fully automated form, the device 60 is provided with an applicator (not shown) controlled by a control device 65. The glue will be applied to the magnet housing 36 visible in the device 60, in this embodiment on the side opposite the flange 51.

Glue attaches the magnet housing 36 to the support base 1. For this purpose, the glue (applied in the liquid state) must be able to flow between the wall of the magnet housing 36 and the wall of the accommodation hole 47. If the magnet housing 36 and the receiving bore 47 both have a circular profile over their entire axial length, it is difficult to ensure that the glue is applied properly.

To overcome this problem, axial or helical grooves 54 may be provided in the outer surface of the magnet housing 36 and/or the wall of the receiving bore 47. As shown in fig. 5A, the preferred solution is to provide such a groove 54 on the outer surface of the magnet housing 36.

Such a slot may not need to be applied if the magnet housing 36 or the receiving bore 47 has a non-circular profile. In the above, with reference to fig. 4A and 4B, it is explained that these components do not necessarily have circular symmetry. For example, if the magnet housing 36 has a flat surface portion 55 (fig. 5A), or even a square cross-section (fig. 4B), or a hexagonal or octagonal cross-section (not shown), a space 45 will automatically be left between the magnet housing 36 and the accommodation hole 47, which space can be filled with glue.

Fig. 7A-7D schematically illustrate radial adjustment of the magnet 35 within the magnet housing 36 according to the present invention. The magnet housing 36 is shown as a solid cylinder with its central axis aligned with the Z-axis (vertical). Perpendicular to the central axis, a magnet bore 71 extends through the magnet housing 36 from side wall to side wall. Parallel to the central axis, a tool cavity 72 extends through magnet housing 36 from top surface 56 to magnet cavity 71.

In a first mounting step, the magnet 35 is pushed laterally into the magnet housing 36, i.e. into the magnet cavity 71 (fig. 7A and 7B), to a certain position "depth" within the magnet cavity 71, as shown in fig. 7C. This position, particularly through the tool cavity 72, may be more or less precise. This figure shows in an exaggerated manner that the dimensions of the magnet bore 71 may be slightly smaller than the dimensions of the magnet 35 so that the magnet 35 is clamped in place by the magnet bore 71.

With the magnet 35 in this position, the magnet housing 36 is inserted into its receiving hole 47 as described above. Now, the tapered adjustment tool 80 is inserted down into the tool cavity 72, as shown in FIGS. 7C and 7D. The tapered front portion of the adjustment tool 80 engages the magnet 35 and pushes it further in the X direction schematically indicated by the solid line towards the hall sensor 37. A reference tool 81 of calibrated thickness (here schematically represented by a dashed line) may be held in front of the hall sensor 37 to ensure that the magnet 35 is pushed to a calibrated distance from the hall sensor 37.

The adjustment tool 80 is now removed and glue is applied into the tool cavity 72. The glue will engage the magnet 35 to secure it in place. Glue will also pass through magnet bore 71 and engage receiving hole 47 to secure magnet housing 36 in place.

It should be clear to a person skilled in the art that the present invention is not limited to the exemplary embodiments discussed above, but that several variations and modifications are possible within the protective scope of the invention as defined in the appending claims. For example, the step of fixing the sensor unit may be performed before or after adjusting the positioning of the reference unit.

Even if certain features are recited in different dependent claims, the invention relates to embodiments comprising these features in common. Even though some features have been described in connection with each other, the invention relates to embodiments in which one or more of these features have been omitted. Features not explicitly described as essential may also be omitted. Any reference signs in the claims shall not be construed as limiting the scope of the claims.

It should be particularly clear to the person skilled in the art that the measuring device proposed by the invention essentially consists of two elements, in the example in question a hall sensor and a magnet, and that the measuring device is essentially sensitive to the displacement of one element relative to the other, since the output signal of the device depends on and, in a first approximation, is proportional to such a displacement. For this reason, the measuring device will be denoted as a displacement measuring device. However, such a displacement may be caused by an external influence, such as a force, such that the output signal is indicative of such an external influence, and the measuring device may be indicated as a measuring device for such an external influence.