Abstract
A force gauge includes a housing, comprising a first and a second plate elements. The gauge further comprises a foil-based sensor element to output an electric signal in response to a force exerted on the sensor element in a thickness direction (T) or in a direction of force application (F), at least one spring element arranged to provide a counter force in T or F and having a defined spring characteristic, and at least one abut element to limit a maximum compression of the sensor element in T or F. The sensor element, the spring element and the abut element are sandwiched between inner sides of the first and the second plate elements and, together, at least partly define a signal characteristic of the force gauge within an operational range with a lower limit (L2) and an upper limit (L1).
Claims
1. A force gauge, comprising: a housing, comprising a first plate element and a second plate element, a foil-based sensor element, adapted to output an electric signal in response to a force exerted on the sensor element in a thickness direction (T) or in a direction of force application (F) of the sensor element, at least one spring element, arranged to provide a counter force in the thickness direction (T) or the direction of force application (F) of the sensor element and having a defined spring characteristic, and at least one abut element, adapted to limit a maximum compression of the sensor element in the thickness direction (T) or direction of force application (F) of the sensor element, wherein the sensor element, the spring element and the abut element are sandwiched between inner sides of the first plate element and the second plate element, and wherein at least the sensor element, the spring element and the abut element together at least partly define a signal characteristic of the force gauge within an operational range with a lower limit (L2) and an upper limit (L1).
2. The force gauge according to claim 1, wherein the defined operational range deviates in at least one of the lower limit and upper limit from a reference operational range which the sensor element has when considered alone.
3. The force gauge according to claim 2, wherein the defined operational range is narrower than the reference operational range, wherein the defined signal characteristic within the defined operational range has an at least quasi-linear component.
4. The force gauge according to claim 1, further comprising at least one biasing element, adapted to apply a preload in the thickness direction (T) or the direction of force application (F) of the sensor element, preferably so as to shift at least one of the lower limit and upper limit.
5. The force gauge according to claim 4, wherein the biasing element is formed as a flat plateau which protrudes from the first or second plate element in the thickness direction (T) or the direction of force application (F) of the sensor element, and wherein the sensor element contacts the plateau in a flat manner.
6. The force gauge according to claim 1, wherein the sensor element and the spring element are arranged as overlapping layers, and wherein the at least one spring element is arranged between the sensor element and a force application area.
7. The force gauge according to claim 1, wherein the spring element is formed as a coil spring.
8. The force gauge according to claim 1, wherein the spring element comprises a through-hole for the passage of a fastening element or guiding element extending in the thickness direction (T) or the direction of force application (F).
9. The force gauge according to claim 1, wherein the spring element is formed as a leaf spring.
10. The force gauge according to claim 9, wherein the spring element is arranged within a recess of the first or second plate element.
11. The force gauge according to claim 1, wherein the abut element is formed by a recess of the first or second plate element in the thickness direction (T) or the direction of force application (F) of the sensor element, and wherein the sensor element is arranged within the recess.
12. The force gauge according to claim 11, wherein an extension height of side walls of the recess is equal or greater than a total thickness of the sensor element.
13. The force gauge according to claim 1, wherein the abut element is formed as a ring element extending from the first or second plate element in the thickness direction (T) or the direction of force application (F) of the sensor element and comprising a through-hole for the passage of a fastening element or guiding element.
14. The force gauge according to claim 1, further comprising an evaluation electronics, operatively connected to at least the sensor element.
15. The force gauge according to claim 14, wherein the evaluation electronics is adapted to be pushed into the housing from a lateral or radial direction or can be pushed out of the housing in a sliding manner.
16. A force measuring system, comprising a plurality of force gauges, each of the force gauges comprising: a housing, comprising a first plate element and a second plate element, a foil-based sensor element, adapted to output an electric signal in response to a force exerted on the sensor element in a thickness direction (T) or in a direction of force application (F) of the sensor element, at least one spring element, arranged to provide a counter force in the thickness direction (T) or the direction of force application (F) of the sensor element and having a defined spring characteristic, and at least one abut element, adapted to limit a maximum compression of the sensor element in the thickness direction (T) or direction of force application (F) of the sensor element, wherein the sensor element, the spring element and the abut element are sandwiched between inner sides of the first plate element and the second plate element, wherein at least the sensor element, the spring element and the abut element together at least partly define a signal characteristic of the force gauge within an operational range with a lower limit (L2) and an upper limit (L1), and wherein the force gauges are arranged in a mesh network.
17. A method of manufacturing a force gauge, comprising: providing a housing, comprising a first plate element and a second plate element, providing a foil-based sensor element, adapted to output an electric signal in response to a force exerted on the sensor element in a thickness direction (T) or in a direction of force application (F) of the sensor element, providing at least one spring element, arranged to provide a counter force in the thickness direction (T) or the direction of force application (F) of the sensor element and having a defined spring characteristic, providing at least one abut element, adapted to limit a maximum compression of the sensor element in the thickness direction (T) or direction of force application (F) of the sensor element, wherein the sensor element, the spring element and the abut element are sandwiched between inner sides of the first plate element and the second plate element, wherein the sensor element, the spring element and the abut element are sandwiched between inner sides of the first plate element and the second plate element, wherein the sensor element and the spring element together at least partly define an application-specific signal characteristic of the force gauge within an operational range with a lower limit (L2) and an upper limit (L1), and wherein the operational range is adjusted by selecting one or more configurations of the sensor element, the spring element and the abut element.
18. The force gauge according to claim 6, wherein the at least one spring element comprises a first spring element having first material characteristics and a second spring element having second material characteristics different to the first material characteristics, and wherein the sensor element is sheathed between the first and second spring element.
19. The force gauge according to claim 18, wherein a shape or the material of the first spring element and the second spring element is selected to load the sensor element over its entire surface.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0048] Exemplary embodiments according to the present disclosure will be described in the following with reference to the following figures.
[0049] FIG. 1 shows in a schematic sectional view a force gauge according to an embodiment.
[0050] FIG. 2 shows in a schematic sectional view a force gauge according to an embodiment. FIG. 3 shows in a schematic sectional view a force gauge according to an embodiment.
[0051] FIG. 4 shows in a schematic exploded view a force gauge according to an embodiment.
[0052] FIG. 5 shows in a schematic exploded view a force gauge according to an embodiment.
[0053] FIG. 6 shows in a schematic exploded view a force gauge according to an embodiment.
[0054] FIG. 7 shows a first operational range of a force gauge, which does not comprise a spring element, and second operation range of a force gauge according to an embodiment of the invention, wherein the second operational range may be obtained by using a spring element that work together with a sensor element of the force gauge.
[0055] FIG. 8 shows in a voltage-force diagram an operational range of a force gauge according to an embodiment of the invention that is defined by an interaction of a sensor element and a spring element of the force gauge, the operational range comprising an at least quasi linear signal characteristic.
[0056] FIG. 9 shows in a force diagram a comparison of a measurement signal of a force gauge according to an embodiment of the invention and a measurement signal of a high-precision sensor specifically designed for the specific application.
[0057] FIG. 10 shows in a flow chart a method of manufacturing a force gauge according to an embodiment of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0058] In the following, a detailed description of exemplary embodiments will be given to explain the invention in more detail.
[0059] FIG. 1 shows in a schematic sectional view a force gauge 100 according to an embodiment. The force gauge 100 may be universally adapted or adjusted to a wide variety of applications for precise force measurement in industry, automotive, medicine, etc.
[0060] The force gauge 100 according to this embodiment comprises a sensor element 110 which is adapted to output an electric signal in response to a force exerted on the sensor element 110 in a thickness direction T of the sensor element 110. By way of example, the sensor element 110 is provided in layer technique, and is particularly provided as a foil-based sensor element. Such a foil-based sensor element may be based on or similar to an FSR as described above. It is noted that the sensor element 100 may also be based on a different sensor technology.
[0061] The force gauge 100 further comprises at least one spring element 120 that is arranged overlapping with the sensor element 110 in the thickness direction of the sensor element 110. The sensor element 110 has a defined spring characteristic, which may be expressed by a specific spring constant, hardness, stiffness, rigidity, or the like, of the spring element 120. By way of example, the sensor element 110 is sheathed by two different spring elements 120, namely a first spring element 120A and a second spring element 120B (see also e.g. FIG. 3). It is noted that the first spring element 120A and the second spring element 120B may have different material characteristics, such as different stiffness, different degrees of hardness, etc. Thus the sensor and/or signal characteristics may be modelled in their basic behavior. The shape and/or the choice of material of the first spring element 120A and the second spring element 120B may ensure that the sensor element 110 is constantly loaded over the entire surface and not only at specific points. The first spring element 120A may primarily provide a suitable support for the sensor element 110 and the second spring element 120B may primarily provide an adjustment mechanism for adjusting the operational range and/or the response of the force gauge 100. In at least some embodiments, there may be one or more further, third spring elements 120, such as spring element 120C, which, in the embodiment according to FIG. 1, is arranged so as to act in the thickness direction T. In this way, the further spring element 120C may be a further part of the adjustment mechanism for adjusting the operational range and/or the response of the force gauge 100. As exemplarily shown in FIG. 1, the one or more spring elements 120 may be selected from a rubber, a foam rubber, a foamed plastic and a mechanical spring, or an combination thereof. In FIG. 1, an upper side of the force gauge 100 represents a force application area.
[0062] In at least some embodiments, the force gauge 100 may further comprise a housing 130, at least one biasing element 140, e.g. an adjustable plate or the like, at least one abut element 150, an evaluation electronic 160, and a power supply 170. In the embodiment according to FIG. 1, components 110, 120 and 140 to 170 of the force gauge 100 are accommodated within the housing 130.
[0063] FIG. 2 shows in a schematic sectional view a force gauge 100 according to an embodiment. Deviating from the embodiment described above with reference to FIG. 1, the force gauge 100 according to this embodiment does not comprise the further, third spring element 120C. Accordingly, the adjustment mechanism for adjusting the operational range and/or the response of the force gauge 100 mainly comprises the spring elements 120A and 120B. It is noted that the force gauge 100 according to this embodiment may comprise the housing 130, which is here formed by the first and second spring elements 120A and 120B. It is noted that a material of the first spring elements 120A and/the second spring element 120B may be chosen from a foam, a mat, a rubber, a silicone, or the like, wherein, in at least some embodiments, a first material associated with the first spring element 120A and a second material associated with the second spring element 120B may differ from each other, Thus, the sensor and/or signal characteristics may be modelled more accurately. As can be seen in FIG. 2, the sensor element 110, the evaluation electronic 160, and/or the power supply 170 may be arranged in a recess of one of the first and second spring element 120A and 120B, wherein these components are at least partly covered by the other one of the first and second spring element 120A and 120B.
[0064] FIG. 3 shows in a schematic sectional view a force gauge 100 according to an embodiment. Deviating from the embodiments described above with reference to FIG. 1 or FIG. 2, in the force gauge 100 according to this embodiment, the evaluation electronic 160 and/or the power supply 170 are arranged separately to the sensor element 110 and the spring elements 120A and 120B.
[0065] FIG. 4 shows in a schematic exploded view a force gauge 100 according to an embodiment. The housing 130 comprises a first plate element 131, which may also be referred to as a base plate or lower plate, and a second plate element 132, which may also be referred to as a cover plate or top plate. According to FIG. 4, the housing 130 and/or the first and second plate element 131, 132 has a rectangular shape. At least one of the first plate element 131 and the second plate element comprises the abut element 150, which is formed as a recess 133 configured to accommodate the sensor element 110. Preferably, the number of recesses 133 corresponds to the number of sensor elements 110. It is noted that this embodiment comprises an exemplary total of four sensor elements 110, wherein the number of recesses 133 is correspondingly also four. One or more sidewalls of the recess 133 have an extension height that is equal or greater than a total thickness of the sensor element 110. In other words, the side walls of the recess 130 may protrude beyond a flat side of the sensing element 110. Further, at least one of the first plate element 131 and the second plate element comprises a further recess 134 configured to accommodate the spring element 120, which is here formed as a leaf spring. Optionally, the spring element 120 comprises a through hole. The first plate element 131 and the second plate element 132 comprise a number of through holes for the passage of a fastening element 135, which comprises, for example, a screw and a nut 136. The spring element 120 and/or its through hole is also configured for the passage of the fastening element 135.
[0066] FIG. 5 shows in a schematic exploded view a force gauge 100 according to an embodiment. In at least this embodiment, the housing 130 and/or the first and second plate element 131, 132 has a cylindrical shape. The spring element 120 is formed as coil spring, that is arranged in a center of the housing 130. The abut element 150 is formed as a ring element, a washer, or the like, arranged at least one of the first plate element 131 and second plate element 132. In this exemplary embodiment, the fastening element 135 comprises a screw arranged so as to passage a through hole and/or a center of the spring element 120. Further, the force gauge 100 comprises a number of guiding elements 135A, which may be formed as e.g. a bolt, or the like. Further, the force gauge 100 comprises a cable routing 137, which for example is formed as a radial at least partially circumferential groove in one of the first and second plate element 131, 132. The cable routing 137 is covered by a cable routing cover 138. Further in at least this embodiment, the biasing element 140 is formed as a flat plateau on which the sensor element 110 is arranged so as to contact the biasing element in a flat manner. The evaluation electronics 160 and/or the power supply 170 are configured to be accommodated within the housing 130 in a sliding manner, for which purpose the housing 130 and/or the evaluation electronics 160 and/or the power supply 170 may comprise a fastening device. The contacting to the sensor element 130 may be provided by sliding contacts, or the like.
[0067] FIG. 6 shows in a schematic exploded view a force gauge 100 according to an embodiment. In at least this embodiment, the housing 130 and/or the first and second plate element 131, 132 has a horseshoe shape. Here, the spring element 120 is formed as a leaf spring, disc spring, or the like, accommodated in the further recess 134, which is exemplary formed at or in the first plate element 131. Further, the abut element 150 is formed as a ring element, which is exemplarily formed at or in, or is arranged at, the second plate element 132. It is noted that this embodiment may also comprise a number of the fastening elements 135 and/or guiding elements 136.
[0068] It is noted that the embodiments according to FIGS. 1 to 6 may be combined with each other. In particular, individual features of these embodiments may be combined in order to adapt the force gauge 100 to individual applications.
[0069] The embodiments described above with reference to FIGS. 1 to 6 may have in common that the sensor element 110 and the at least one spring element 120 (e.g. spring elements 120A, 120B and 120C) together at least partly define a signal characteristic of the force gauge 100 within an operational range with a lower limit and an upper limit. In particular, the defined operational range may deviate in at least one of the lower limit and upper limit from a reference operational range which the sensor element 110 would have when considered alone (i.e. without the spring element 120). Depending on e.g. the individual application of the force gauge 100, the at least one biasing element 140 and/or at least one abut element 150 may be optionally provided to further adjust the operational range.
[0070] FIG. 7 illustrates this interaction between the sensor element 110 and the at least one spring element 120 and/or the at least one biasing element 140 and/or the least one abut element 150. On the left, a first operational range is shown in a voltage-force diagram. This first operational range may represent the reference operational range as described above. On the right, a second operational range is shown in a voltage-force diagram. This second operational range may represent the defined operational range of the force gauge 100 according to the embodiments described above, which may be obtained by using the at least one spring element 120 together with the sensor element 110. As can be seen in FIG. 7, providing the at least one spring element 120 shifts the operational range of the force gauge 100 from e.g. 0 to 250 N to e.g. 0 to 3000 N, wherein these values a only examples that may differ from application to application. Optionally, the defined operational range may further be adjusted by providing the at least one biasing element 140 and/or the least one abut element 150.
[0071] FIG. 8 shows in a voltage-force diagram the operational range of the force gauge 100 according to an embodiment of the invention. The operational range is defined and may be adjustable by an interaction of the sensor element 110 and the at least one spring element 120 of the force gauge 100, wherein the defined operational range comprises an at least quasi-linear signal characteristic within an upper limit L1 and a lower limit L2. Accordingly, the at least one spring element 120 may be selected from different variants so as to adjust the operational range and/or the upper limit L1 and/or the lower limit L2 to a specific application of the force gauge 100. As can be seen in FIG. 8, the defined operational range is narrower than the reference operational range, wherein the defined signal characteristic within the defined operational range has the at least quasi-linear component. Within the defined operation range, the force gauge 100 may allow precise force measurement that may be adapted to a wide variety of applications.
[0072] As exemplarily described with reference to FIG. 1, the operational range and/or the upper limit L1 and/or the lower limit L2 may be further adjusted by optionally providing the at least one biasing element 140 and/or the at least one abut element 150. In particular, the at least one biasing element 140 may be adapted to apply a preload in the thickness direction T of the sensor element 110, preferably so as to shift at least one of the lower limit L2 and the upper limit L1. Further, the at least one abut element 150 may be adapted to limit a maximum compression of the sensor element 110 in the thickness direction T of the sensor element 110 so as to shift at least one of the lower limit L2 and upper limit L1. Likewise, providing one or more of the third spring elements 120C may also allow to individually adjust the operational range and/or the upper limit L1 and/or the lower limit L2 to a specific application of the force gauge 100.
[0073] FIG. 9 illustrates in a force diagram a comparison of a measurement signal of the force gauge 100 according to an embodiment of the invention and a measurement signal of a high-precision sensor (not shown) specifically designed for the specific application. As can be seen, the application-specific selection of the at least one spring element 120 allows high precision measurement of forces when still using the sensor element 110. In FIG. 9, the solid line indicates the measurement signal provided by the force gauge 100 according to an embodiment and the dashed line indicates the measurement provided by the high-precision sensor (not shown) specifically designed for the specific application. As can be seen, the two lines or signals are largely congruent. This means that the force gauge 100 can be set most accurately for a specific application by a suitable selection of one or more of the spring elements 120 described above.
[0074] FIG. 10 shows in a flow chart a method of manufacturing a force gauge according to an embodiment.
[0075] In a first step S1, the housing 130 comprising the first plate element 131 and the second plate element 132 according to any one of the above embodiments is provided.
[0076] In a second step S2, the sensor element 110 is provided. The sensor element 110 is adapted to output an electric signal in response to a force exerted on the sensor element 110 in the thickness direction T of the sensor element 110.
[0077] In a third step S3, the at least one spring element 120 is arranged overlapping with the sensor element 110 in the thickness direction of the sensor element 110, wherein the at least one spring element 120 has a defined spring characteristic.
[0078] In a fourth step S4, the at least one abut element 150, adapted to limit a maximum compression of the sensor element 110 in the thickness direction T and/or direction of force application F (which corresponds to the thickness direction T as shown in FIG. 1, of the sensor element 110.
[0079] As described above, the sensor element 110 and the at least one spring element 120 together at least partly define an application-specific signal characteristic of the force gauge 100 within an operational range with a lower limit L2 and an upper limit L1.
