Sensor device for measuring a mechanical load

Abstract

The present invention relates to a sensor device (1) for measuring a mechanical load, comprising - a first member (2) to be mechanically loaded; - a first sensor assembly (3) arranged on the first member (2); - a printed circuit board (PCB) (4); - a second sensor assembly (5) arranged on the PCB (4) and spaced apart from the first sensor assembly (3), wherein the output signal of the second sensor assembly (5) indicates the distance between the first and second sensor assemblies (3, 5); and - an electronic assembly (11, 12, 13, 14) arranged on the PCB (4) and configured to receive the output signal of the second sensor assembly (5), wherein the sensor device (1) is configured such that the distance (19) between the first and second sensor assemblies (3, 5) depends on the mechanical load applied to the first member (2).

Description

Technical Field

[0001] The present invention relates to a sensor device for measuring mechanical loads. Background Art

[0002] Mechanical loads can be determined, for example, using different techniques. For example, if a conductive material is subjected to tensile stress, the length of the material will increase, and thereby the resistance of the material will increase. Similarly, if the material is subjected to compressive stress, the length will decrease, but the width will increase. This principle is used in strain gauges to measure mechanical loads, such as stress, strain, or weight applied to a structure such as a workpiece or a machine.

[0003] The most common type of strain gauge includes an insulating flexible carrier that supports a metal foil pattern. The strain gauge can be attached to the structure to be measured by a suitable adhesive. When the structure deforms, the foil deforms, causing a change in its resistance. For example, the deformation of the foil includes stretching or bending.

[0004] Typical strain gauge foils require at least 15 minutes for their correct installation, which is usually carried out manually. Therefore, a disadvantage of these strain gauges is that they require a relatively long time for installation. Reducing the installation time and the associated costs would be advantageous.

[0005] Although many strain gauges can measure foil deformation with high precision, not all practical applications require such high precision. In some applications, a cheaper solution with a lower accuracy grade is needed. Summary of the Invention

[0006] In view of the above problems, the present invention has been made.

[0007] According to the present invention, there is provided a sensor device for measuring mechanical loads. The sensor device includes

[0008] - a first member to be mechanically loaded;

[0009] - a first sensor assembly arranged on the first member;

[0010] - a printed circuit board (PCB);

[0011] - a second sensor assembly arranged on the PCB and spaced apart from the first sensor assembly, wherein an output signal of the second sensor assembly indicates a distance between the first and the second sensor assemblies; and

[0012] - an electronic assembly arranged on the PCB and configured to receive the output signal of the second sensor assembly.

[0013] The sensor device enables the distance between the first and the second sensor assemblies to depend on the mechanical load applied to the first member.

[0014] The PCB mechanically supports and electrically connects the electrical components and the second sensor assembly. Thus, by providing the PCB, the installation and production of the sensor device can be greatly simplified compared to the above-mentioned resistive foil strain gauges.

[0015] The mechanical load applied to the first member may cause the first member to deform, such as bending or stretching. Depending on the application, the mechanical load can be a tensile load and / or a compressive load. Due to the deformation of the first member, the first sensor assembly can move towards or away from the second assembly. Thus, the distance between the first and second sensor assemblies is a measurement of the mechanical load applied to the first member. In some examples, the distance between the first sensor assembly and the second assembly increases as the mechanical load is applied to the first member. In other examples, the distance between the first sensor assembly and the second assembly decreases when the mechanical load is applied to the first member. There may be an air gap between the first and second sensor assemblies. Generally, the first and second sensor assemblies do not contact each other.

[0016] The distance between the first and second sensor assemblies can be calculated or estimated using the output signal of the second assembly. Alternatively or additionally, the distance between the first and second assemblies is determined by comparing the output signal of the second sensor assembly with a reference value corresponding to a specific distance, which can be pre-stored in a look-up table. It is also possible to use a combination of calculation and comparison with a reference value for the determination of the distance between the first and second sensor assemblies. By determining the displacement of the first sensor assembly relative to the second sensor assembly, the mechanical load applied to the first member can be determined.

[0017] In an alternative embodiment, the output signal of the second sensor is used to directly determine the mechanical load applied to the first member, for example, as mentioned above, by using the output signal for calculation or by comparing the output signal with a reference value corresponding to a specific mechanical load.

[0018] In some examples, the first sensor assembly includes a magnetic material. For example, a part of the first member can include a magnetized region. Additionally, the first sensor assembly can be a magnet fixed to the first member. The second sensor assembly can be configured to sense the magnetic field strength of the first sensor assembly. Thus, the first sensor assembly can be a passive sensor assembly, while the second sensor assembly can be an active sensor assembly. For example, the output signal of the second sensor assembly can be proportional to the magnetic field measured by the second sensor assembly. That is, a small distance between the first and second sensor assemblies can be characterized by a relatively high magnetic field measured by the second sensor assembly. A large distance between the first and second sensor assemblies can be characterized by a relatively low magnetic field measured by the second sensor assembly.

[0019] The second sensor assembly may include an inductive sensor, a Hall sensor, or a magnetoresistive sensor. Other sensors configured to measure a magnetic field or its derivatives may also be considered. The cost of such a sensor assembly is much lower than the cost associated with strain gauges with foils based on thin-film technology.

[0020] The PCB may be positioned relative to the first member such that the position of the second sensor assembly remains constant independent of the mechanical load applied to the first member. The sensor device may include a predetermined portion for receiving the mechanical load. The predetermined portion for receiving the mechanical load may be part of the first member, but this is not necessary.

[0021] In some embodiments, the sensor device includes a first wall and an opposing second wall. The first member may include a first end and a second end. The first and second ends of the first member may be attached to the first wall and the second wall, respectively. The first end of the PCB may be attached to the first wall in a cantilever manner, and the second sensor assembly is arranged on the second end of the PCB. The predetermined portion for receiving the mechanical load may be the second end of the first member.

[0022] The first member and the PCB may extend substantially parallel to each other in the unloaded state of the first member. In the loaded state of the first member, a varying distance may exist between the first member and the PCB, and thus, the PCB and the first member may no longer extend parallel to each other.

[0023] The sensor device may further include a second member. The second member may have substantially the same shape as the first member. The PCB may be arranged in the space between the first member and the second member. The first member and the second member may extend parallel to each other in the loaded state and / or the unloaded state of the first member.

[0024] In a further development, the sensor device includes a housing surrounding the PCB. The first member, the second member, the first wall, and / or the second wall may be part of the housing. At least two of the above components may be integrally formed by the housing. The first end of the PCB may be mounted in a cantilever manner inside the housing. It is contemplated that the second sensor assembly is arranged on the second end of the PCB. The second end of the PCB may be spaced apart from the second wall. The PCB may extend into the cavity defined by the housing.

[0025] The first component and / or the second component may include, for example, a beam or a plate. The materials and dimensions of the housing, the first component, the second component, the first wall, and / or the second wall may be selected to be able to withstand mechanical loads and provide a measurable displacement of the first sensor assembly relative to the second sensor assembly. In common applications, the above elements may be made of metals such as steel, aluminum, or the like. The sensor device may be designed to withstand mechanical loads of at least 100 kg and / or at most 10,000 kg. In some cases, the sensor device is configured such that the position of the second sensor assembly remains constant independent of the mechanical load applied to the first component. For example, this may be achieved by having a rigid substrate for the PCB and / or through the design of the housing and / or by attaching the PCB to a location that is substantially non-deformable when the first component is mechanically loaded. In some examples, the PCB attachment location may be located at a position opposite to a predetermined portion for receiving the mechanical load. For example, when a mechanical load is applied, the PCB is typically attached to a portion of the housing that has a maximum deformation of less than 10% or less than 5%.

[0026] In some cases, the PCB includes a substrate made of a flexible material. In some examples, the PCB may include a slot defining a tongue and a frame surrounding the tongue. The frame may be attached to the first wall and the second wall. Additionally, the second sensor assembly may be arranged on the tongue such that the position of the second sensor assembly depends on the mechanical load applied to the first component. Thus, in this case, the mechanical load applied to the first component may cause the tongue to deform. The slot and / or the tongue may be substantially U-shaped or C-shaped.

[0027] The PCB may include dedicated sensor circuitry for reading, processing, and storing the output signals of the second sensor assembly. The electronic assembly may include at least one of an analog-to-digital converter (ADC), a processing unit, a storage device, and / or a communication unit.

[0028] The sensor device may further include a fixing device for fixing the sensor device, especially its housing, to a structure in a cantilever manner. The sensor device may be used in a device or machine configured to carry variable loads.

[0029] The present invention also provides an apparatus or a machine for carrying a variable load such as a vehicle, a boom lift or a telescopic forklift including the sensor device as described above. By introducing the sensor device into these apparatuses, machines or systems, the risk of overload can be significantly reduced. In addition, the stability of the apparatus or the machine can be improved. For example, the sensor device can be part of a load management information system. The load management information system can provide an indication to the operator of the weight of the load on the machine and / or the position of the load in space. For example, the sensor device can be mounted on the shaft of the machine, preferably on the load-bearing shaft, where the sensor device measures the deflection of the shaft when a change in load occurs. These changes in the load can provide an indication of the stability of the machine to the load management system. When the load stability approaches its limit, the sensor device can be configured to send a signal to the control system, and the control system will issue a cabin alarm and prevent the operation of functions that further reduce the stability. Description of the Drawings

[0030] In conjunction with the accompanying drawings, further features, characteristics and advantages of the present invention will become apparent from the following description of the embodiments.

[0031] Figure 1 A longitudinal cross-section of the sensor device is schematically shown.

[0032] Figure 2 The sensor device in a side view is schematically shown.

[0033] Figure 3 The longitudinal cross-section of the sensor device connected to the structure is schematically shown Figure 1 is schematically shown.

[0034] Figure 4 A top view of the PCB is schematically shown.

[0035] Figure 5 A top view of another PCB is schematically shown.

[0036] In the following, for the sake of convenience of description, similar or equal features are denoted by the same reference numerals. Detailed Description of the Embodiments

[0037] Figure 1 A longitudinal cross-section of the sensor device 1 is shown. Figure 1 The cross-section shown in Figure 2 is obtained along section A-A of

[0038] The sensor device 1 includes a housing 10, which includes a first member 2 and an opposite second member 6, a first side wall 7 and an opposite second side wall 8. In the illustrated embodiment, the first member 2 may be a beam extending in the horizontal direction (x-direction). The second member 6 extends parallel to the first member 2 at least in the unloaded state of the sensor device 1 and may also be designed as a beam. Depending on the actual application, the first and second members 2, 6 may also be formed as plates or have other geometries. The first member 2 includes a first end 30 and a second end 31. The first and second ends 30, 31 of the first member 2 may be attached to the first side wall 7 and the second side wall 8, respectively. The side walls 7, 8 extend perpendicular (z-direction) from the first and second members 2, 6 and connect the two members 2, 6 to each other. The housing 10 may be closed by two additional side walls (not shown) that are parallel to each other. In the depicted embodiment, the first member 2, the second member 6 and the side wall 7 are integrally formed, i.e., formed from one part. The side wall 8 is a separate part that can be fixed to the first and second members 2, 6 using fasteners 26 such as screws.

[0039] The housing 10 may be made of a metallic material such as steel, which is configured to be able to withstand high mechanical loads, for example from 100 kg to 10,000 kg.

[0040] The housing 10 may include fixing means 23 for fixing the sensor device 1 to the structure 24 in a cantilever manner (also refer to Figure 3 ).

[0041] The housing 10 defines a cavity 20 for enclosing a printed circuit board (PCB) 4. The PCB 4 may have a rectangular perimeter and includes a first end 20 and an opposite second end 21. The first end 20 of the PCB 4 may be mounted inside the housing 10 in a cantilever manner. In this way, the PCB 4 extends into the cavity 20 of the housing 10. For example, the first end 20 may be attached to a step 27 that may be integrally formed with the first wall 7 and / or the second member 6. The second end 21 may be spaced apart from the second wall 8, the first member 2 and the second member 6.

[0042] The sensor device 1 includes a first sensor assembly 3 and a second sensor assembly 5 for measuring the mechanical load applied to the first member 2. More specifically, the first sensor assembly 3 is arranged on the first member 2, particularly at its second end 31. In the illustrated embodiment, the first sensor assembly 3 is attached to the side of the first member 2 facing the cavity 20 of the housing 10. The second sensor assembly 5 is arranged on the second end 21 of the PCB. The second sensor assembly 5 can be located on the PCB 4 such that it faces the first sensor assembly 2. In the unloaded state of the sensor device 1, there is a predetermined distance 19 between the first sensor assembly 3 and the second sensor assembly 5. Thus, the first and second sensor assemblies 3, 5 are separated from each other by an air gap. The sensor device 1 is configured such that the distance 19 between the first and second sensor assemblies 3, 5 depends on the mechanical load applied to the first member 2. When a mechanical load is applied to the first member 2, the distance 19 decreases. In other implementations, the distance 19 can increase when the first member 2 is mechanically loaded.

[0043] The first sensor assembly 3 can include a magnetizable material, such as a magnet attached to the first member 2. The second sensor assembly 5 is configured to sense the magnetic field strength of the magnetic material of the first sensor assembly 3. For example, the second sensor assembly 5 can be an inductive sensor, a Hall sensor, or a magnetoresistive sensor.

[0044] The output signal of the second sensor assembly 5 indicates the distance between the first and second sensor assemblies 3, 5.

[0045] For example, the output signal of the second sensor assembly 5 can be proportional to the magnetic field measured by the second sensor assembly 5. That is, a small distance between the first and second sensor assemblies 3, 5 can be characterized by a relatively high magnetic field measured by the second sensor assembly 5. A large distance between the first and second sensor assemblies 3, 5 can be characterized by a relatively low magnetic field measured by the second sensor assembly 5.

[0046] The PCB 4 is positioned relative to the first member 2 such that the position of the second sensor assembly 5 remains constant independent of the mechanical load applied to the first member 2.

[0047] Figure 3 A longitudinal cross-section of the sensor device 1 connected to the structure 24 is schematically shown. Further, Figure 1 of. The unloaded state of the sensor device 1 and the loaded state of the sensor device 1 are shown. The first member 2 and the PCB 4 extend substantially parallel to each other in the unloaded state of the first member 2. Under load conditions, the elements are denoted by the same reference numerals with an apostrophe (e.g., 2', 3', 6'). As Figure 3 shown in Figure 3As explained, a mechanical load F is applied to a predetermined load receiving portion, which is the second end 31 of the first member 2' near the second side wall 8. A bending moment is applied to the first and second members 2', 6', causing displacement of the first sensor assembly 3'. However, the PCB 4 attached to the first wall 7 substantially maintains its position, and thus the second sensor assembly 5 is not moved by the mechanical load F. In the loaded state of the first member 2', the distance between the first member 2' and the PCB 4 varies in the horizontal direction (x-direction), and thus, the PCB 4 and the first member 2' no longer extend parallel to each other. As a result, the distance 19 between the first and second sensor assemblies 3, 5 decreases, which can be measured by a higher magnetic field near the second sensor assembly 5. From Figure 3 it can be seen that the first and second members 2' and 6' run parallel to each other in the loaded and unloaded states.

[0048] The magnetic field value included in the output signal of the second sensor assembly 5 can be directly used to calculate the magnitude of the mechanical load F at the second end 31 of the first member 2. Alternatively, the measured magnetic field can be compared with a reference value stored in a look-up table to determine the mechanical load F. The look-up table can be stored in the storage unit 13 described below. Generally, the sensor device 1 is designed such that mechanical loads between 100 kg and 10,000 kg can be measured.

[0049] Figure 4 and 5 illustrates a top view of two different PCBs 4 Figure 4 . As shown, the PCB 4 serves as a mechanical support for a number of electronic components 11, 12, 13, 14. At least one of the electronic components 11, 12, 13, 14 or all of the electronic components 11, 12, 13, 14 are configured to receive the output signal of the second sensor assembly 5.

[0050] The PCB 4 can include dedicated sensor circuitry for reading, processing, and storing the output signal of the second sensor assembly 5. For example, an analog-to-digital converter 11, a processing unit 12, a storage unit 13, a communication unit 14, and a power supply 15 that can be envisioned and arranged on the PCB 4. It should be noted that the PCB may also carry more or fewer electronic components. The PCB 4 can include a plurality of conductive tracks, pads, and other features etched from one or more copper sheet layers laminated on a non-conductive substrate 25. The electronic components 11, 12, 13, 14, 15 and the second sensor assembly 5 are typically soldered to the PCB 4 to electrically connect and mechanically secure them to the PCB 4.

[0051] The analog-to-digital converter (ADC) 11 can convert the analog output signal of the second sensor assembly 5 into a digital signal. For example, the ADC can convert an input analog voltage or current into a digital number representing the magnitude of the voltage or current. Typically, the digital output is a two's complement binary number proportional to the input, but there are other possibilities. The ADC 11 can feed the digital output to the processing unit 12.

[0052] The processing unit 12 can be any arrangement of electronic circuits, electronic components, processors, program components, etc. configured to store and / or execute programming instructions to direct the operation of the other functional components 5, 11, 13, 14 of the sensor device 1, and can be implemented, for example, in any combination of hardware, software, and / or firmware. The processing unit 12 can be configured to read, process, and / or analyze the sensor signal of the second sensor assembly 5 and / or the digital signal provided by the ADC 11. In particular, the processing unit 12 can determine the distance 19 and / or the magnitude of the mechanical load applied to the second member 2 based on the output signals of the second sensor assembly 5 and / or the ADC 11.

[0053] According to some implementations, the storage unit 13 can be used to store the information sensed by the second sensor assembly 5. The storage unit 13 can include volatile and / or non-volatile memory and can store instructions that, when executed by the processing unit 12 or the second sensor assembly 5, cause methods and processes to be executed by the processing unit 12 or the second sensor assembly 5.

[0054] The communication unit 14 can include any combination of hardware, software, and / or firmware configured to facilitate the establishment, maintenance, and use of any number of communication links. In embodiments, the communication unit 14 of the sensor device 1 facilitates wired or wireless communication with the processing unit 12. In embodiments, the communication component 14 can also facilitate communication with external devices (not shown), such as, for example, facilitating coordinated operation between the sensor device 1 and external devices. For example, a user can request sensor output signals, sensor values, etc. through an external device connected to the communication unit 14.

[0055] In addition, the power supply 15 can be envisioned to provide power to the other operating components of the sensor device 1 (e.g., the analog-to-digital converter 11, the second sensor assembly 5, the processing device 12, the storage unit 13, and the communication unit 14), and can be any type of power supply suitable for providing the desired performance and / or lifetime requirements of the sensor device 1. In various embodiments, the power supply 15 can include one or more batteries, which can be charged (e.g., using an external energy source). The power supply 15 can include one or more capacitors, energy conversion mechanisms, etc. The power supply of the sensor device 1 is well known and will not be discussed in more detail herein.

[0056] Figure 1, 3 The substrate 25 of the PCB 4 shown in FIGS. 2 and 4 is made of a rigid material to ensure that the position of the second sensor assembly 5 remains constant independent of the orientation of the sensor device 1.

[0057] Figure 5 An embodiment with a slightly different top view of the PCB 4 is shown. The PCB 4 includes a substrate 25 made of a flexible material. The PCB may include a slot 17 defining a tongue 16 and a frame 18 surrounding the tongue 16. The slot 17 and the corresponding tongue 16 may be substantially U-shaped or C-shaped. The tongue 16 is attached to the frame 18 in the region of the first end 20 of the PCB 4. Thus, the tongue 16 is connected to the frame 18 only at one of its sides. The frame 18 is attached to at least the first side wall 7 and the second side wall 8. The frame may also be connected to the other two side walls. The second end of the PCB 4 lies on the end of the tongue 16. If a mechanical load is applied to the housing 10, the frame 18 can be bent or stretched together with the first member 2, depending on the magnitude and direction of the mechanical force. For example, in the loaded and unloaded states of the sensor device 1, the frame 18 may extend parallel to the first member 2. However, the tongue 16 extends into the cavity 20 of the housing 10. When a force is applied to the first member 2, the tongue 16 can bend towards or away from the first member 2. For example, the second sensor assembly 5 can move towards the first sensor assembly 3, and the distance 19 decreases depending on the mechanical load. The second sensor assembly 5 is arranged on the tongue 16 such that the position of the second sensor assembly 5 depends on the mechanical load applied to the first assembly 2. Thus, by Figure 5 the embodiment shown in FIGS. 2 and 4, a more sensitive sensor device 1 can be provided.

[0058] The present invention also provides a device or machine (not shown) for carrying a variable load such as a vehicle, a boom lift or a telescopic forklift. The machine or device includes the sensor device 1 as described above. For example, the device or machine may include a load management information system (not shown), where the sensor device 1 is part of the load management information system. The load management information system can provide an indication of the weight of the load on the device / machine and / or the position of the load in space to the operator. For example, the sensor device 1 can be mounted on the load-bearing axis of the device / machine, such as the rear axle of a telescopic forklift, where the sensor device 1 measures the deflection of the axis (e.g., its casting) when a load change occurs. These changes in the load can provide an indication of the longitudinal stability of the machine as it moves through the entire load map. When the load stability approaches its limit, the sensor device 1 can be configured to send a signal to the control system, which will issue a cabin alarm and prevent the operation of functions that further reduce stability.

[0059] List of reference numerals

[0060] 1 Sensor device

[0061] 2 First component

[0062] 3 First sensor assembly

[0063] 4 Printed circuit board

[0064] 5 Second sensor assembly

[0065] 6 Second component

[0066] 7 First side wall

[0067] 8 Second side wall

[0068] 10 Housing

[0069] 11 Analog-to-digital converter

[0070] 12 Processing unit

[0071] 13 Storage unit

[0072] 14 Communication unit

[0073] 15 Power supply

[0074] 16 Tongue

[0075] 17 Groove

[0076] 18 Frame

[0077] 19 Distance

[0078] 20 First end

[0079] 21 Second end

[0080] 22 Cavity

[0081] 23 Hole

[0082] 24 Structure

[0083] 25 Substrate

[0084] 26 Fastener

[0085] 27 Step

[0086] 30 First end

[0087] 31 Second end

[0088] F Mechanical load.

Claims

1. A sensor device (1) for measuring a mechanical load, comprising - a first member (2) to be mechanically loaded; - a first sensor assembly (3) arranged on the first member (2); - a PCB (4); - a second sensor assembly (5) arranged on the PCB (4) and spaced apart from the first sensor assembly (3), wherein an output signal of the second sensor assembly (5) indicates a distance (19) between the first sensor assembly (3) and the second sensor assembly (5); and - an electronic assembly (11, 12, 13, 14) arranged on the PCB (4) and configured to receive the output signal of the second sensor assembly (5), - a second member (6), the PCB (4) being arranged in a cavity (22) between the first member (2) and the second member (6), wherein the sensor device (1) is configured such that the distance (19) between the first sensor assembly (3) and the second sensor assembly (5) depends on the mechanical load applied to the first member (2).

2. The sensor device (1) according to claim 1, characterized in that, The first sensor assembly (3) comprises a magnetic material, and the second sensor assembly (5) is configured to sense a magnetic field strength of the magnetic material.

3. The sensor device (1) according to claim 2, characterized in that, The second sensor assembly (5) comprises an inductive sensor, a Hall sensor or a magnetoresistive sensor.

4. The sensor device (1) according to any one of claims 1 to 3, characterized in that Further comprising a first wall (7) and an opposite second wall (8), wherein a first end portion (20) of the PCB (4) is attached to the first wall (7) in a cantilever manner, and the second sensor assembly (5) is arranged on a second end portion (21) of the PCB (4).

5. The sensor device (1) according to any one of claims 1 to 3, characterized in that, In a no-load state of the first member (2), the first member (2) and the PCB (4) extend parallel to each other.

6. The sensor device (1) according to any one of claims 1-3, characterized in that The sensor device (1) is configured such that the distance between the first sensor assembly (3) and the second sensor assembly (5) decreases or increases when a mechanical load is applied to the first member (2).

7. The sensor device (1) according to claim 1, characterized in that, In a loaded and no-load state of the first member (2), the first member (2) and the second member (6) extend parallel to each other.

8. The sensor device (1) according to claim 4, characterized in that, Further comprising a housing (10) surrounding the PCB (4), wherein the first member (2), the second member (6), the first wall (7) and the second wall (8) are part of the housing (10).

9. The sensor device (1) according to any one of claims 1 to 3, characterized in that The electronic assembly (11, 12, 13, 14) comprises at least one of an analog-to-digital converter (11), a processing unit (12), a storage unit (13) and a communication unit (14).

10. The sensor device (1) according to any one of claims 1-3, characterized in that, Further comprising a fixing device (23) for fixing the sensor device (1) to a structure (24) in a cantilever manner.

11. The sensor device (1) according to any one of claims 1 to 3, characterized in that The PCB (4) is positioned relative to the first member (2) such that a position of the second sensor assembly (5) remains constant independent of the mechanical load applied to the first member (2).

12. The sensor device (1) according to claim 4, characterized in that, The PCB (4) includes a groove (17) defining a tongue (16), and a frame (18) surrounding the tongue (16), wherein the frame (18) is attached to the first wall (7) and the second wall (8), and the second sensor assembly (5) is arranged on the tongue (16) such that the position of the second sensor assembly (5) depends on the mechanical load applied to the first member (2).

13. The sensor device (1) according to claim 12, characterized in that, The groove (17) and / or the tongue (16) is U-shaped or C-shaped.

14. A machine for carrying a variable load, the machine having a sensor device (1) as claimed in any one of the preceding claims.

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