Elastic bearing element

Abstract

Elastic bearing element (1) with at least one first body (11), with at least one second body (12) and with at least one elastomeric element (10) which is arranged in the direction of a force flow between the first body (11) and the second body (12), furthermore, with at least one sensor (2) which is designed and arranged to detect a force in the force flow between the first body (11) and the second body (12) directly or indirectly, characterized by the fact that the sensor (2) at least one elastic layer (20), at least one first electrode (21) and at least a second electrode (22) exhibits wherein the elastic layer (20) is arranged at least sectionally between the first electrode (21) and the second electrode (22), wherein the sensor (2) is arranged in the force flow between the first body (11) and the second body (12) such that the force changes the distance between the two electrodes (21, 22) and the force can be at least partially detected by this means, wherein the elastic layer (20) comprises a rubber compound comprising at least a silicone rubber as the sole rubber component and microhollow spheres.

Description

[0001] The present invention relates to an elastic bearing element according to claim 1.

[0002] The installation of load cells and force transducers to measure forces at the point of elastic support is known. These sensors are arranged in addition to the elastic support, for example, parallel or in series with the force flow to be measured. Such commonly available sensors are based on strain gauge technology or piezoelectric sensors, sometimes with integrated amplifiers. For example, bending beams can be used with strain gauge sensor elements glued to them. Alternatively, air pressure measurements can be taken inside air springs.

[0003] The disadvantage here is that an additional component is required for each installation. This can lead to additional costs and require additional installation space. Furthermore, the sensor may need to be protected from external influences.

[0004] A further disadvantage of using strain gauge sensors is that they can only detect stresses or bending in a single spatial direction. This can lead to inaccurate measurements if force components occur in other directions. Overcoming this limitation by using multiple strain gauge sensors can increase the complexity and cost of both the sensors themselves and the electronics for evaluating and converting the stress values, thus driving up the overall price.

[0005] AT 389 171 B discloses a device for measuring loads in composite bodies using strain gauge sensor elements.

[0006] A disadvantage of measuring air pressure in air springs can be that air is compressible, and therefore the measured pressure value may be lower than the actual force exerted.

[0007] A general disadvantage of pressure measurements with fluids is the removal of air present in the system. Venting the system often proves difficult, especially when the air needs to be removed as completely as possible. The compressibility of air in the system can reduce the accuracy of the measurement.

[0008] DE 102011085920 A1 discloses a rolling bearing of a pulley, which is designed to determine loads in a rope guided over the pulley.

[0009] WO 2006 040 781 A2 discloses a sensor for measuring physical quantities with at least one capacitive measuring cell, the electrical properties of which change in response to the physical quantities.

[0010] One object of the present invention is to enable force measurement at the location of an elastic bearing element of the type described above to be carried out more simply, cost-effectively, and / or more accurately than previously known methods. In particular, it should be possible to dispense with additional components such as load cells.

[0011] The problem is solved according to the invention by an elastic bearing element with the features according to claim 1. Advantageous embodiments are described in the dependent claims.

[0012] The present invention thus relates to an elastic bearing element comprising at least one first body, at least one second body, and at least one elastomeric element, which is arranged in the direction of force flow between the first body and the second body. The elastomeric element is elastically designed, i.e., it can change its shape under the influence of force and return to its original shape when the acting force is removed. Preferably, the elastomeric element comprises or is formed from a vulcanized rubber compound.

[0013] The elastic bearing element further comprises at least one sensor, which is designed and arranged to detect a force in the force flow between the first body and the second body, either directly or indirectly. For direct force detection, the sensor can be arranged directly in the force flow between the two bodies. For indirect force detection, the sensor can be arranged outside the force flow, whereby, for example, forces can be transmitted to the sensor via a fluid arranged in the force flow. The two bodies are designed to be rigidly connected to another body, so that force transmission can occur via the elastomeric element, whereby dynamic force transmission can be dampened by the elastic properties of the elastomeric element. The two bodies are preferably rigid, in particular made of metal.The two bodies can also be described as stop elements.

[0014] The elastic bearing element is characterized in that the sensor comprises at least one elastic layer, at least one first electrode, and at least one second electrode, wherein the elastic layer is arranged at least partially between the first and second electrodes. The elastic layer preferably comprises or is formed from an elastomeric material. The elastic layer is non-electrically conductive, i.e., electrically insulating or dielectric, in order to electrically isolate the two electrodes from each other. The elastomeric material of the elastic layer preferably comprises or is formed from a vulcanized rubber compound, whereby, for example, polyurethanes can also be used.An electrode is an electrical conductor that interacts with a second (counter-)electrode and a medium located between the two electrodes, such as the elastic layer in this case. Electrodes can be electrical conductors, such as metal or graphite, or be made entirely of them. Electrodes can be planar or linear. The distance between the two electrodes can be measured, for example capacitively, using such a sensor.

[0015] The sensor is positioned in the force path between the first and second bodies in such a way that the force changes the distance between the two electrodes, allowing the force to be at least partially detected. In other words, the sensor is designed to infer the magnitude of the force between the two bodies, which changes this distance, from the distance between the electrodes. Due to the elastic properties of the elastomer element, the distance between the two electrodes can decrease as the force increases. Conversely, as the force decreases, the distance between the two electrodes can increase again, returning to the distance of the unloaded state.

[0016] The elastic layer comprises a rubber compound containing at least one silicone rubber as the sole rubber component and microhollow spheres. Any silicone rubber known to a competent person can be used. Preferably, silicone rubbers also known as poly(organo)siloxanes can be used. These possess groups accessible for crosslinking reactions, consisting predominantly, but not exclusively, of hydrogen atoms, hydroxyl groups, and vinyl groups, which may be located in the chain or at the chain ends.

[0017] Both cold-curing (RTV = room temperature curing) and hot-curing (HTV = high-temperature curing) silicone rubbers can be used. RTV silicone rubbers are available in one-component and two-component systems. The silicone rubber can also be used as a premix of polymer, filler, and oil, as is common practice on the market.

[0018] To adjust the viscosity, the rubber compound may contain at least one plasticizer. Any plasticizer known to a qualified professional and compatible with the specific silicone rubber can be used. The use of silicone oil has proven particularly advantageous due to its compatibility with silicone rubber. Cross-linking silicone oils, which participate in the cross-linking of the rubber compound and are often referred to as cross-linkable silicone oils, have proven especially suitable. These significantly reduce the potential leaching of plasticizers, a phenomenon sometimes observed in prior art insulating tubing.

[0019] To increase the elasticity and compressibility of the rubber compound, it is given a porous structure. This simultaneously improves the thermal and acoustic insulation properties of the rubber compound. This porous structure is achieved by incorporating microspheres into the rubber compound. These microspheres, often simply called microbeads, are hollow spheres (microspheres) with a diameter in the micrometer range, made of glass, phenolic resin, carbon, or thermoplastic materials. They are available in expandable form, filled with a blowing agent and expanding upon heating, or in pre-expanded form, where expansion is already complete.Preferably, the rubber mixture contains 2 to 200 phr microspheres, particularly preferably 2 to 30 phr, most preferably 2 to 15 phr already expanded microspheres made of thermoplastic material, so that the rubber mixture already has a pore structure before the formation of the elastic layer or before crosslinking.

[0020] In addition to the increased elasticity and compressibility of the rubber compound, microspheres offer the further advantage of forming a closed-pore structure, which is better suited for insulation purposes due to reduced convection within the pores. The higher the quantity of expanded microspheres, the better the insulation effect due to the increased pore size. However, excessively large quantities of microspheres can lead to processing problems during compound production or application.

[0021] Alternatively, the rubber compound can contain 10 to 200 phr glass microspheres. This variant yields a rubber compound with higher stability but lower elasticity and compressibility, since glass microspheres, unlike thermoplastic microspheres, are not compressible. This reduced elasticity and compressibility, which may still be greater than that of known sensors of this type, can be accepted in favor of the increased stability and lifespan of the elastic layer, depending on the application.

[0022] The present invention is based on the understanding that, due to the comparatively high elasticity or compressibility of the sensor's elastic layer, an exceptionally sensitive sensor can be created using such a sensor, which can deliver correspondingly accurate measurements. At the same time, such a sensor can be easily and robustly integrated into such an elastic bearing element. In this way, a comparatively accurate measurement of the force in the force flow of such an elastic bearing element can be achieved without using external components that may require protection. Furthermore, such a sensor or elastic bearing arrangement can be implemented simply and / or cost-effectively. Such a sensor or elastic bearing arrangement can also be robust against environmental influences such as water, moisture, dust, mud, stones, and the like.

[0023] The sensor can be positioned within the elastomer element or between the elastomer element and one of the two bodies. This allows for an arrangement, depending on the application, to be configured to detect the force of the respective force flow as effectively and accurately as possible.

[0024] Another advantage is that such a sensor can be positioned directly in the force flow between the two bodies for direct force measurement. This eliminates the need for force transmission, e.g., via a fluid.

[0025] Furthermore, it is advantageous that such a sensor can be integrated into or attached to the elastomer element before its vulcanization. This can simplify the manufacturing of the elastic bearing element as a whole, thus enabling the sensor function.

[0026] A further advantage is that such an elastic bearing element can also be retrofitted by inserting such a sensor into an existing elastic bearing element. Thus, the properties and advantages achievable according to the invention can be retrofitted and utilized in existing, suitable elastic bearing elements.

[0027] Multiple such sensors, which may be identical or differently designed and arranged, can also be used. This allows measurements to be taken independently at several points. These multiple measurements can then be evaluated, for example, to detect tilting and / or rotation of the elastic bearing element, as well as to determine the degree of tilting or rotation.

[0028] The sensor can be designed and arranged in all sorts of shapes. For example, it can be laid out in a straight line, curved, spiral, circular, as an inner and outer circle, in a cross shape, triangular, square, etc. This allows for the most representative force measurement possible, depending on the application.

[0029] According to one aspect of the present invention, the sensor is coaxially configured, wherein the first electrode is cylindrically surrounded, at least partially, preferably completely, by the elastic layer, and wherein the elastic layer is cylindrically surrounded, at least partially, preferably completely, by the second electrode. This allows for a compact arrangement of the sensor elements, resulting in a space-saving sensor. Furthermore, a sensor can be created which, due to its rotational symmetry, can be used as the axis of rotational symmetry regardless of its orientation about the longitudinal axis, since a radial change in distance leads to the same change in the distance between the two electrodes in any orientation. Thus, the same change in distance can always be detected, regardless of the orientation about the longitudinal axis.

[0030] According to a further aspect of the present invention, the first electrode is designed as an electrically conductive wire made of solid material or as a stranded wire, wherein the wire preferably comprises or consists of copper, aluminum, silver, or gold. A solid wire can be easily manufactured and processed. A stranded wire can have a higher ductility than a solid wire, so that the sensor can withstand the force loads for a longer period and thus have a longer service life. The materials copper, aluminum, silver, or gold can have high electrical conductivity, whereby, depending on the application, the degree of electrical conductivity, the material costs, and possibly other properties of the materials must be weighed against each other.

[0031] According to a further aspect of the present invention, the second electrode is configured as an electrically conductive layer in the form of a film or as a braid, knitted fabric, or woven fabric, wherein the layer preferably comprises or consists of copper, aluminum, silver, or gold. By using a layer, a second electrode with a maximum surface area can be created, so that a force flow can be detected over a correspondingly large area, provided the layer is at least substantially flat. When using the second electrode layer in a cylindrical shape in a coaxially configured sensor, the first electrode can be enclosed by the second electrode to create the coaxial arrangement. In any case, a layer in the form of a film can be produced simply and cost-effectively. The alternative configuration of the layer as a braid, knitted fabric, or woven fabric, similar to a stranded wire as the first electrode, can result in higher extensibility than with a film.A braid is a flat structure created by braiding, the regular interlacing of several strands of flexible material. A woven fabric is a textile structure made up of at least two thread systems crossed at right angles or nearly at right angles. The difference between a braid and a woven fabric lies in the fact that the threads are not introduced at right angles during braiding. A knitted fabric is a thread system produced by forming loops.

[0032] According to a further aspect of the present invention, the sensor also has at least one protective layer, which is preferably arranged directly on the side of at least one electrode, preferably the second electrode, facing the elastomer element. This protects the electrode on this side. This protective layer can serve to protect the electrode in its uninstalled state, but also to protect it from the elastomer element in its installed state.

[0033] According to a further aspect of the present invention, the protective layer is designed to be electrically insulating. This allows the electrode on this side to be electrically isolated, so that an electrical sensor function can be performed better compared to another electrode on the side facing away from the protective layer.

[0034] According to a further aspect of the present invention, the protective layer is elastically designed, preferably comprising a silicone, and more preferably consisting of a silicone. In this way, force transmission through the protective layer can be as undisturbed as possible, so that despite the use of the advantageous properties of the protective layer, the sensory detection of the force is affected as little as possible, or not at all. This can be achieved simply, robustly, and / or cost-effectively through the use of silicone.

[0035] According to a further aspect of the present invention, at least one electrode, preferably the second electrode, is in direct contact with the elastomeric element, wherein the electrode preferably has, at least partially, preferably completely, an adhesion promoter, and preferably also an adhesive elastomer mixture, on the side facing the elastomeric element, so that adhesion is established between the electrode and the elastomeric element. This allows for the most direct and therefore undisturbed force transmission possible. The use of an adhesion promoter and, optionally, an additional adhesive elastomer mixture can improve the bond between the electrode and the elastomeric element, thus increasing or ensuring direct force transmission and improving the accuracy of the force measurement. The service life of the sensor can also be extended as a result.

[0036] According to a further aspect of the present invention, the sensor is elongated, and at least in sections, it is arranged at least substantially transversely to the direction of force flow along its elongated extension. An elongated sensor is understood to be one that extends significantly further in one direction, namely its longitudinal direction, than in the other two Cartesian spatial directions, namely the transverse direction and the vertical direction. Viewed in cylindrical coordinates, the elongated sensor extends significantly further along its longitudinal axis than in the radial direction. The elongated extension of the sensor allows for the detection of the largest possible area within the elastomeric element without unduly interrupting the force transmission through the elastomeric element.Positioning the elongated sensor at least substantially, preferably precisely, perpendicular to the direction of force flow can be achieved with the shortest possible sensor. The force of the force flow acting perpendicularly on the sensor can also be measured directly.

[0037] According to a further aspect of the present invention, the sensor extends at least partially, preferably completely, in a straight line. This can simplify the subsequent integration of such a sensor into an elastomer element, since a straight hole, either blind or through, can be made from the outside to accommodate the sensor. This can be done easily and quickly in manufacturing, for example, by drilling, due to the straightness of a bore. Furthermore, a sensor extending in a straight line can detect as much of the elastomer element as possible, which can keep the associated costs low.

[0038] According to a further aspect of the present invention, the sensor extends at least partially, preferably completely, in a ring shape. This allows for a comparatively large area over which the sensor can detect the force of the force flow. This can increase the accuracy of the detection.

[0039] According to a further aspect of the present invention, the sensor is designed with two electrodes, the first being continuous and the second being discontinuous. This allows two measurements to be acquired with one sensor, enabling the detection of force distribution, e.g., whether the load is concentrated on the left or right. Simultaneously, the respective force values ​​can be used to detect the individual forces and calculate the difference in load. The total force can be determined by summing the two individual measurements.

[0040] According to a further aspect of the present invention, the sensor is designed such that the change in the distance between the two electrodes is proportional to the force of the force flow between the first body and the second body. This can be achieved by selecting the geometries of the electrodes and their distance from each other, depending on the application. A proportional relationship between distance or change in distance and force is understood to be a linear relationship, which can be evaluated accordingly simply and directly.

[0041] According to a further aspect of the present invention, the sensor is designed such that the capacitance between the two electrodes is proportional to the distance between the two electrodes. Accordingly, the linear relationship between the capacitance and the distance can be detected and evaluated simply and directly.

[0042] According to a further aspect of the present invention, the elastic layer of the sensor exhibits at least substantially the same elasticity as the elastomer element. This allows the sensor to be positioned in the force flow in such a way that the force can be detected as representatively as possible, because, due to the identical elasticity of the elastomer element and the sensor, the same force can flow through the sensor as through the elastomer element. This can improve the quality of the detected sensor signal and simplify its evaluation.

[0043] Several embodiments of the present invention are explained below in connection with the following figures. These show: Fig. 1 a schematic longitudinal section of a sensor of an elastic bearing element according to the invention; Fig. 2 a schematic cross-section of the Fig. 1; Fig. 3 a perspective view of an elastic bearing element according to the invention in a first embodiment; Fig. 4 a perspective view of an elastic bearing element according to the invention in a second embodiment; and Fig. 5 a perspective view of an elastic bearing element according to the invention in a third embodiment.

[0044] Fig. Figure 1 shows a schematic longitudinal section of a sensor 2 of an elastic bearing element 1 according to the invention. Fig. Figure 2 shows a schematic cross-section of the Fig. 1. The sensor 2 extends longitudinally along its longitudinal axis L, from which a radial direction R extends perpendicularly. Radially inside the sensor 2 is a first electrode 21, which can also be referred to as the inner electrode 21. Radially around the first electrode 21 is a cylindrical elastic layer 20, which surrounds the first electrode 21 in the circumferential direction U. The elastic layer 20 is surrounded radially outside by a second electrode 22 in the circumferential direction U.

[0045] The two electrodes 21, 22 are electrically conductive and are contacted externally along the longitudinal axis L (not shown). The intervening layer 20 is elastic and electrically insulating, allowing, for example, the detection of capacitance between the two electrodes 21, 22. If a force or pressure is applied externally to the second electrode 22, the radial distance between the two electrodes 21, 22 decreases at this point. This can be detected via a corresponding change in capacitance and converted into a force or pressure value, so that the sensor 2 can also be referred to as a force or pressure sensor 2.

[0046] The elastic layer 20 comprises a rubber compound containing at least one silicone rubber as its sole rubber component and microhollow spheres. This allows for the creation of an elastic, electrically insulating layer 20 between the two electrodes 21, 22, which is also highly compressible, enabling the sensor to detect even small forces with comparatively high accuracy.

[0047] Optional and in the Fig. 1 and Fig. Figure 2 shows that the second electrode 22 is enclosed in the circumferential direction U by a ring-shaped protective layer 23 to protect against external influences. The protective layer 23 is made of an elastic and electrically insulating silicone compound. The protective layer 23 can also be omitted.

[0048] Fig. Figure 3 shows a perspective view of an elastic bearing element 1 according to a first embodiment of the invention. A sensor 2 is integrated into the elastic bearing element 1 in a straight line and perpendicular to the main deflection direction A of the elastic bearing element 1. The elastic bearing element 1 has an elastomer body 10 in the form of a rubber spring 10, which is arranged between a first body 11 as a lower stop element 11 and a second body 12 as an upper stop element 12. The sensor 2 is arranged within the elastomer body 10 such that forces from the force flow in the main deflection direction A of the elastomer body 10 can be detected as described above.

[0049] Fig. Figure 4 shows a perspective view of an elastic bearing element 1 according to a second embodiment of the invention. In this case, the sensor 2 is designed with an interrupted section, while the first electrode 21 is continuous.

[0050] Fig. Figure 5 shows a perspective view of an elastic bearing element 1 according to a third embodiment of the invention. In this case, the sensor 2 is arranged in a ring shape to increase the effective sensor area. Reference symbol list (part of the description) A Main deflection direction of the elastic bearing element 1 L Longitudinal axis R radial direction U circumferential direction 1 elastic bearing element 10 elastomer element; Rubber spring 11 first body; lower stop element 12 second body; upper stop element 2 Sensors; Pressure sensor; Force sensor 20 elastic layer; rubber compound 21 first electrode; inner electrode 22 second electrode; outer electrode 23 Protective layer

Claims

[1] Elastic bearing element (1) with at least one first body (11), with at least one second body (12) and with at least one elastomeric element (10) which is arranged in the direction of a force flow between the first body (11) and the second body (12), furthermore, with at least one sensor (2) which is designed and arranged to detect a force in the force flow between the first body (11) and the second body (12) directly or indirectly, characterized by , that the sensor (2) at least one elastic layer (20), at least one first electrode (21) and at least a second electrode (22) exhibits wherein the elastic layer (20) is arranged at least sectionally between the first electrode (21) and the second electrode (22), wherein the sensor (2) is arranged in the force flow between the first body (11) and the second body (12) such that the force changes the distance between the two electrodes (21, 22) and the force can be at least partially detected by this means, wherein the elastic layer (20) comprises a rubber compound comprising at least a silicone rubber as the sole rubber component and microhollow spheres. [2] Elastic bearing element (1) according to claim 1, characterized by , that the sensor (2) is designed coaxially, wherein the first electrode (21) is cylindrically surrounded at least partially, preferably completely, by the elastic layer (20), and wherein the elastic layer (20) is cylindrically surrounded at least partially, preferably completely, by the second electrode (22). [3] Elastic bearing element (1) according to claim 1 or 2, characterized by, that the first electrode (21) is designed as an electrically conductive wire made of solid material or as a stranded wire, wherein the wire preferably comprises or consists of copper, aluminium, silver or gold. [4] Elastic bearing element (1) according to any one of the preceding claims, characterized by , that the second electrode (22) is designed as an electrically conductive layer in the form of a foil or as a braid, knit or fabric, wherein the layer preferably comprises or consists of copper, aluminium, silver or gold. [5] Elastic bearing element (1) according to any one of the preceding claims, characterized by , that the sensor (2) further comprises at least one protective layer (23) which is arranged, preferably directly, on the side facing the elastomer element (10) of at least one electrode (21, 22), preferably the second electrode (22). [6] Elastic bearing element (1) according to claim 5, characterized by, that the protective layer (23) is electrically insulating. [7] Elastic bearing element (1) according to claim 5 or 6, characterized by that the protective layer (23) is elastically designed, wherein the protective layer (23) preferably comprises a silicone, and is particularly preferably made of a silicone. [8] Elastic bearing element (1) according to any one of claims 1 to 4, characterized by , that at least one electrode (21, 22), preferably the second electrode (22), is in direct contact with the elastomer element (10), wherein the electrode (21, 22) preferably has an adhesion promoter, preferably also an adhesion elastomer mixture, at least sectionally, preferably completely, on the side facing the elastomer element (10), so that adhesion is established between the electrode (21, 22) and the elastomer element (10). [9] Elastic bearing element (1) according to any one of the preceding claims, characterized by, that the sensor (2) is elongated, wherein the sensor (2) is arranged at least section by section in the direction of its elongated extension at least substantially transversely to the direction of the force flow. [10] Elastic bearing element (1) according to claim 9, characterized by that the sensor (2) extends in a straight line, at least section by section, preferably completely. [11] Elastic bearing element (1) according to claim 9 or 10, characterized by that the sensor (2) extends in a ring shape, at least in sections, preferably completely. [12] Elastic bearing element (1) according to any one of the preceding claims, characterized by , that the sensor (2) is formed in two parts, wherein the first electrode (21) is continuous and the second electrode (22) is interrupted. [13] Elastic bearing element (1) according to any one of the preceding claims, characterized by, that the sensor (2) is designed such that the change in the distance between the two electrodes (21, 22) is proportional to the force of the force flow between the first body (11) and the second body (12). [14] Elastic bearing element (1) according to any one of the preceding claims, characterized by , that the sensor (2) is designed such that the capacitance between the two electrodes (21, 22) is proportional to the distance between the two electrodes (21, 22) from each other. [15] Elastic bearing element (1) according to any one of the preceding claims, characterized by , that the elastic layer (20) of the sensor (2) has at least substantially the same elasticity as the elastomer element (10).

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