Sensor arrangement for detecting deformation events

Abstract

Sensor arrangement (1) for detecting deformation events, comprising a measuring body (3) having a surface that can be elastically deformed by external forces and / or by internal forces acting on the measuring body (3), and comprising a piezosensor (31) comprising a piezoactive plastic film (32) provided with at least two electrodes (33, 34) arranged at a distance from one another, and comprising a strain sensor (23) designed as a strain gauge for detecting a deformation of the measuring body (3); wherein the measuring body (3) is designed as an actuator housing of an actuator (2), wherein the actuator housing delimits a working chamber (4) in which a working element (5) is accommodated so as to be movable along a movement path (6) between a first functional position and a second functional position,wherein the working element (5) divides the working chamber (4) into a first variable-size working space (7) and a second variable-size working space (8), wherein the first working space (7) is assigned a fluid connection which is designed for ventilation and de-aeration of the first working space (7), wherein the piezo sensor (31) and the strain sensor (23) are accommodated in a sensor groove (12) of the actuator housing and are accommodated between the measuring body (3) and a pressure body (25) coupled to the measuring body (3), wherein the pressure body (25) has a pressure surface which is geometrically similar to the surface of the measuring body (3) provided with the piezo sensor (31) and / or the strain sensor (23), so that the piezo sensor (31) and / or the strain sensor (23) rests against the surface of the measuring body (3) in a force-fitting manner, in particular exclusively in a force-fitting manner.

Description

[0001] The invention relates to a sensor arrangement for detecting deformation events.

[0002] Such a sensor arrangement can, for example, be used on components for automation technology that may be exposed to changing forces during intended use, whereby these changing forces may, among other things, also manifest themselves in deformation events for the respective component.

[0003] DE 10 2016 204 314 A1 discloses a linear motion device with a rod extending in the direction of a longitudinal axis and a rotor which is mounted on the rod via at least one row of rolling elements so as to be movable at least in the direction of the longitudinal axis, wherein each row of rolling elements is assigned a rotor rolling surface on the rotor, wherein said rolling elements bear against the rotor rolling surface in a load-transmitting manner at least in a supporting region of the rotor rolling surface, wherein the rotor is provided with at least one strain sensor which is flat in design so as to define a measuring surface, wherein strains, regardless of where they occur on the measuring surface, influence a measuring signal of the strain sensor, wherein the measuring surface extends in the direction of the longitudinal axis over at least 80% of the length of the supporting region.

[0004] DE 10 2015 218 891 A1 discloses a test arrangement for testing a test body with a sensor device for providing sensor data, wherein the sensor device comprises at least one sensor for attachment to the surface of the test body and for generating at least one sensor signal, wherein the sensor has two electrodes and a dielectric and wherein the dielectric is arranged between the two electrodes so that the sensor forms a capacitor with a capacitance, wherein the sensor signal is dependent on the capacitance and forms at least part of the sensor data, and with an evaluation device for evaluating the sensor data, wherein the evaluation device is designed to determine an extension of the test body and a body vibration of the test body on the basis of the sensor data.

[0005] EP 1 719 992 B1 describes a linear rolling bearing with an approximately U-shaped guide carriage arranged on a guide rail, which has two legs and a back connecting the two legs, wherein the guide carriage engages around the guide rail with its two legs, and wherein rolling elements roll under preload on raceways of the guide carriage and the guide rail, wherein the raceways are formed on mutually facing sides of the guide rail and the two legs, and wherein at least one sensor designed as a strain gauge is attached to the guide carriage, wherein the sensor designed as a strain gauge is attached to the side of the back of the guide carriage facing the guide rail, centrally between the two legs.

[0006] DE 11 2016 004 941 B4 discloses a position detection device in which a rail element of a motion guide device is provided with a through-hole into which a fastening element for securing the rail element to a base can be inserted. A carriage, which is movably connected to the rail element via a rolling element, is provided with magnets that generate a magnetic field in the direction of the rail element. Magnetic sensors, which detect a change in the magnetic fields of the magnets with the movement of the magnets relative to the rail element, are arranged within the magnetic fields of the magnets.

[0007] US 2014 / 0 366 646 A1 discloses a detector comprising a first substrate, a second substrate, a circuit board provided between the first substrate and the second substrate, and an element mounted on the circuit board, the element outputting a signal in response to an external force, a hole being formed in the circuit board at a position where the element is placed, and a first convex part being provided on the first substrate, which first convex part is inserted into the hole and projects toward the element.

[0008] From JP 2013 - 234 899 A a strain gauge holder is known which consists of a holder body with two plate-like side wall parts which are to be attached to a side surface of a pipe and which further comprises a gauge pressing element for pressing a strain gauge against the side surface of the pipe and a feed mechanism for applying a compressive force to the gauge pressing element and is configured such that the gauge pressing element is moved by the feed mechanism in a guide groove which is formed by the side wall parts and presses the strain gauge against the side surface of the pipe.

[0009] JP 2013 060 983 A discloses a fluid pressure cylinder device with a load transducer capable of easily draining oil accumulated in a space within the load transducer to prevent deterioration in measurement accuracy. To this end, the load transducer includes an elastic deformation portion formed in a thin cylindrical shape, elastically deformable by a load axially applied thereto, and to which a deformation sensor is attached. Furthermore, flange portions formed at both ends of the elastic deformation portion are connected to an outer end surface of a rod cover. A mounting flange for mounting the load transducer to an external frame is connected to the outer flange portion of the load transducer.A piston rod includes sealing elements provided between the piston rod and the rod cover to extend through the load converter and the mounting flange. The load converter includes a drain port for discharging fluid collected in a space between the elastic deformation portion and the piston rod to the outside.

[0010] DE 10 2014 221 294 A1 discloses a sensor device, in particular for a gripping device, with at least one sensor field having at least two pressure sensors, and with an elastomer layer arranged over the at least one sensor field.

[0011] JP 2020-186787 A discloses a fluid control valve capable of detecting a fluid control abnormality caused by the impact of fluid on a valve seat or a valve body made of an elastic body and a change in a physical property of the elastic body. To this end, the fluid control valve includes a vibration sensor for detecting vibrations generated by an impact force when the valve body rests on the valve seat, and further includes a determination part for determining that a flow control abnormality occurs when the vibration detected by the vibration sensor is equal to or smaller than a predetermined threshold.

[0012] The object of the invention is to enable a cost-effective or essentially comprehensive analysis of deformation events on an automation component.

[0013] This object is achieved with a sensor arrangement of the type mentioned at the outset having the features of claim 1.

[0014] The measuring body is the component whose condition is to be monitored with the help of associated sensors. Associated with the measuring body is a piezo sensor comprising a piezoactive plastic film, in particular made of polyvinylidene fluoride. The piezoactive plastic film is provided with at least two spaced-apart electrodes that enable measurement of charge transport that can occur in the piezoactive plastic film upon a change in strain, in particular tapping an electrical voltage from the plastic film or measuring a current at the plastic film.With the help of such a piezo sensor, which can be pressed against the measuring body, an electrical charge change is generated depending on a deformation of the measuring body and / or depending on vibrations of the measuring body. This change can be converted by a suitable evaluation device into a status signal for the measuring body. Furthermore, a strain sensor is provided, which can be used in the same way as the piezo sensor to detect elastic or elastic and plastic deformations of the measuring body. By combining the sensor signals from the sensors, useful information about the status of the measuring body can be determined, particularly in the manner of an observer, i.e., a virtual sensor.

[0015] According to the invention, it is provided that the piezo sensor and the strain sensor are accommodated between the measuring body and a pressure body coupled to the measuring body, wherein the pressure body has a pressure surface which is geometrically similar to the surface of the measuring body provided with the piezo sensor and / or the strain sensor, so that the piezo sensor and / or the strain sensor rests against the surface of the measuring body in a force-fitting manner, in particular exclusively in a force-fitting manner.The pressure body serves to couple the piezo sensor and / or the strain sensor to the measuring body in a manner that, on the one hand, ensures the transfer of deformations from the measuring body to the piezo sensor and / or the strain sensor, while, on the other hand, eliminating the need to create a material connection between the measuring body and the piezo sensor and / or the strain sensor. This is particularly advantageous when retrofitting the sensors to a measuring body. The pressure body is preferably made of a material with high elasticity, such as a rubber-elastic material, to ensure advantageous and uniform force transmission to the sensors.

[0016] According to the invention, the measuring body is designed as an actuator housing of an actuator. The actuator housing defines a working chamber in which a working element is movably accommodated along a movement path between a first functional position and a second functional position. This working element divides the working chamber into a first variable-size working chamber and a second variable-size working chamber. A fluid connection configured for ventilating and de-aerating the first working chamber is assigned to the first working chamber. Such an actuator can be designed, in particular, as a single-acting or double-acting pneumatic cylinder or as a pneumatic rotary actuator.In such an actuator, the objective to be achieved with the sensor arrangement can, for example, be to obtain as complete a status image as possible, independent of a pneumatic supply system, from which, for example, signs of wear such as wear of cylinder bores or sealing elements can be read out.

[0017] Preferably, the piezo sensor is electrically connected, in particular via a two-wire connection, to an evaluation device designed to detect time-varying electrical charges in the plastic film. The evaluation device processes the signals from the piezo sensor, in particular amplifies them, and generates information therefrom, which can be provided, for example, to a higher-level controller.

[0018] In an advantageous development of the invention, it is provided that the evaluation device comprises a transimpedance amplifier, in particular designed as a low-noise operational amplifier, and is designed to evaluate signals from the piezo sensor for structure-borne sound events and / or deformation events.

[0019] It is expedient if the plastic film of the piezo sensor is provided in some areas with a conductor track, particularly a meandering one, which is electrically connected to the evaluation device, wherein the evaluation device is designed to determine the temperature of the piezo sensor. This enables temperature determination to be carried out directly at the piezo sensor, which can be used to temperature compensate the sensor signal of the piezo sensor in order to increase the measurement accuracy of the piezo sensor.

[0020] In a further embodiment of the invention, it is provided that the strain sensor is electrically connected, in particular via a four-wire connection, to an evaluation device and that the evaluation device is designed to evaluate signals from the strain sensor for deformation events.

[0021] Preferably, the evaluation device is designed for a combined evaluation of signals from the piezo sensor and / or the strain sensor with the signals from a position sensor. Knowing the position of an actuator element that is movably mounted on or in the measuring body and whose relative position may depend, for example, on a working pressure in the measuring body, allows for an advantageous interpretation of the signals from the piezo sensor and / or the strain sensor.

[0022] It is advantageous if the evaluation device is designed to detect structure-borne sound events based on sensor signals from the piezo sensor and pressure change events based on sensor signals from the strain sensor. For example, if the measuring body is configured as an actuator housing of an actuator, this makes it possible to determine whether an actuator element of the actuator has encountered an obstacle, such as a component being pressed into a workpiece, during a relative movement relative to the actuator housing caused by a pressure change event. In this case, a structure-borne sound event occurs, which can be detected using the piezo sensor.

[0023] In an advantageous development of the invention, it is provided that an insulating film is arranged between the actuator housing and the piezo sensor and / or between the actuator housing and the strain sensor. This insulating film is electrically conductive on one side, in particular as a copper-clad polyimide film (Kapton film), with an electrically conductive surface of the insulating film facing the piezo sensor and / or the strain sensor. The insulating film ensures electrical insulation of the piezo sensor and / or the strain sensor from the measuring body, which is usually made of a metallic material. Furthermore, the electrically conductive surface of the insulating film ensures protection against interference and, where applicable, interference emission for the piezo sensor and / or the strain sensor.For this purpose, it can be provided to ensure an advantageous electrical contact connection between the insulation film and the evaluation device, which is preferably realized on a printed circuit, with the aid of contact springs, which are intended to ensure a reliable electrical connection of the insulation film to the ground potential of the evaluation device.

[0024] It is expedient if the pressure body is made of a rubber-elastic material that has, in particular, evenly spaced, electrically conductive sections that are insulated from one another by electrically insulating sections and designed for electrically connecting the piezo sensor and / or the strain sensor. Such an embodiment for the pressure body ensures a dual function, since in addition to providing contact pressure on the piezo sensor and / or the strain sensor, electrical signal transmission can also take place via the pressure body, for example, between the piezo sensor and / or the strain sensor and a printed circuit board resting on the pressure body.

[0025] For this purpose, it is provided in particular that the evaluation device is formed on an electrical circuit board which is provided on a largest surface with electrical conductor tracks which rest at least partially on the electrically conductive sections of the pressure body.

[0026] Advantageous embodiments of the invention are illustrated in the drawing. Fig. 1 is a purely schematic lateral sectional view of a first embodiment of a sensor arrangement comprising a measuring body designed as a pneumatic cylinder and a sensor group comprising a strain sensor, a temperature sensor and a piezo sensor serving as a structure-borne sound sensor, Fig. 2 a purely schematic front view of a sensor arrangement not belonging to the invention, in which gripper fingers of a gripper serve as measuring bodies and are each equipped with a piezo sensor, and Fig. 3 a purely schematic front view of a sensor arrangement not belonging to the invention, in which a valve body of a fluid-conducting component designed as a manually operable control valve serves as a measuring body and is provided with a piezo sensor.

[0027] One in the Fig. 1, a purely schematically illustrated sensor arrangement 1 comprises an actuator 2, which is designed as a double-acting pneumatic cylinder, and two identically designed sensor groups 21, of which one sensor group 21 is described in more detail below as representative of both sensor groups 21. The actuator 2 comprises an actuator housing 3, which serves as a measuring body and in which a working chamber 4 is formed. In the working chamber 4, a working piston 5 is accommodated so as to be linearly movable along a movement axis 6, which divides the working chamber 4 into a first working chamber 7 of variable size and a second working chamber 8 of variable size. Each of the working chambers 7, 8 is assigned a working connection (not shown in detail) with a respective mouth opening 10, 11, which enables an individual inflow of compressed air into the respective working chamber 7, 8 and an individual outflow of compressed air from the respective working chamber 7, 8.

[0028] Each of the two sensor groups 21 is fixed in a sensor groove 12 of the actuator housing 3, which is only shown schematically. For example, it is provided that the sensor group 21 has a Fig. 1, a temperature sensor 22, a strain sensor 23, a position sensor 24, and a piezo sensor 31. The temperature sensor 22, the strain sensor 23, and the piezo sensor 31 are designed for almost direct contact with a groove base 13 of the sensor groove 12, while the position sensor 24 is arranged at a distance from the groove base 13.

[0029] For example, temperature sensor 22 is a semiconductor temperature sensor with negative temperature coefficients, also known as an NTC temperature sensor. Temperature sensor 22 serves to detect the temperature of groove base 13. Two electrically conductive contact pads 26 are arranged on an upper side of temperature sensor 22, enabling sampling of the electrical signal that can be provided by temperature sensor 22.

[0030] The strain sensor 23 is designed purely as an example as a strain gauge and provides an electrical signal at contact fields 27 that is dependent on a strain of the strain sensor 23. The strain sensor 23 thus enables the detection of a change in strain in the region of the groove base 13, wherein this change in strain is caused in particular by an increase or decrease in pressure in the respective working chamber 7 or 8. From the electrical signal of the strain sensor 23, a conclusion can thus be drawn about the pressure prevailing in the respective working chamber 7 or 8. It is preferably provided that the strain sensor 23 is arranged in the groove base 13 in such a way that it detects strains transversely to a main extension direction of the sensor groove 12.By this orientation of the strain sensor 23, pressure-induced strains of the actuator housing 3 are advantageously detected, while force reactions on the actuator housing 3, such as can occur due to reaction forces on the working piston 5, remain at least largely without influence on the strain sensor 23, so that a very precise pressure detection for the pressure prevailing in the actuator housing 3 is ensured.

[0031] The piezo sensor 31 comprises a piezoactive plastic film 32, which is made purely by way of example from the material polyvinylidene fluoride and which is provided on both sides with a metallic coating, forming an upper electrode 33 and a lower electrode 34. For example, a through-hole connection extending from the lower electrode through the plastic film 32 to the upper side of the plastic film, where a contact field 36 is formed, is provided. To prevent an electrically conductive connection between the upper electrode 33 and the contact field 36, the metallic coating on the upper side of the plastic film 32 is partially interrupted.

[0032] For advantageous electrical contacting of the contact pads 26 of the temperature sensor 22, the contact pads 27 of the strain sensor 23, as well as the upper electrode 33 and the contact pad 36 of the piezo sensor 31, a pressure body 25 is provided. This pressure body is designed as a so-called zebra element or conductive rubber and is realized as a regular layer structure of insulating and electrically conductive layers. Purely by way of example, the insulating layers and the electrically conductive layers can each be made of a silicone material, whereby the electrically conductive layers can be realized, for example, with a filling of electrically conductive carbon material or with electrically conductive wire pieces.A division of the electrically conductive layers, which are each separated by electrically insulating layers, is selected such that each of the contact fields 26, 27, 36 as well as the upper electrode 33 can be reliably contacted and an electrical connection with electrical conductor tracks 42 of a printed circuit board 41 designed as a printed circuit is ensured.

[0033] As can be seen from the detailed representation of the Fig. 1, each of the contact pads 26 of the temperature sensor 22 and each of the contact pads 27 of the strain sensor 23 is provided with two independent electrical conductor tracks, whereby a signal transmission between the temperature sensor 22 and an evaluation device 43 designed as a microprocessor and arranged on an upper side of the circuit board 41, as well as the strain sensor 23 and the evaluation device 43, can be realized in each case using four-wire technology in order to ensure that interference on the signals of the temperature sensor 22 and the strain sensor 23 is minimized. Since the piezo sensor 31 has a high impedance, a signal transmission to the evaluation device 43 can be provided here using two-wire technology.

[0034] In order to achieve advantageous overall shielding for the sensor group 21, it is provided, purely by way of example, to enclose the sensor group 21 with a foil tube 28 provided with a copper coating 29 on the inside. The foil tube 28 is made, for example, from a polyimide film (which is sold under the trade name Kapton, among other things). The circuit board 41 is provided at its end with a first connector 44, which is designed to receive an electrical conductor arrangement (not shown), which can be used to supply electrical power to the sensor group 21 and to transmit output signals from the sensor group 21. Instead of the foil tube 28, a U-shaped profiled foil arrangement can also be provided.

[0035] In addition to the temperature sensor 22, the strain sensor 23 and the piezo sensor 31, the sensor group 21 comprises a position sensor 24, which can be designed in particular as an inductive position sensor or Hall position sensor and which is designed to detect the position of the working piston 5 in the respective end region of the actuator housing 3.

[0036] By way of example, it is provided that the position sensor 24 has a sensor interface 30, via which an electrical supply to the position sensor 24 and a sampling of sensor signals from the position sensor 24 is possible. It is preferably provided that a microprocessor (not shown) arranged in the position sensor 24 is electrically connected to a second connector 45 on the circuit board 41 via an electrical conductor connection (likewise not shown), whereby signals from the evaluation device 43 can be made available to the microprocessor of the position sensor 24 for further processing, in order to be able to carry out joint processing of the position sensor signals with the signals from the temperature sensor 22, the strain sensor 23 and the piezo sensor 31.

[0037] For example, it can be provided that the signals from the strain sensor 23 are used to determine the force acting on the piston rod 9 of the actuator 2. Furthermore, the signals from the position sensor 24 can be used to determine the position of the working piston 5 of the actuator 2. The evaluation device 43 can also be designed to evaluate the signals from the piezo sensor 31 for structure-borne sound events, such as those that can occur, for example, when the piston rod 9 strikes an object, as can be the case, for example, when carrying out an entry process or when carrying out a pulse introduction to an object lying loosely on a conveyor belt in order to change the direction of movement of the object.The signals of the temperature sensor 22 are used in particular to perform temperature compensation for the signals of the piezo sensor 31, whose sensor signals are significantly temperature-dependent.

[0038] In the Fig. In the sensor arrangement shown only schematically in Figure 2 and not forming part of the invention, opposingly movable gripper fingers 53 are mounted on a gripper housing 54 of a parallel gripper 52. A drive device (not shown in detail) is arranged in the gripper housing 54, which enables the opposing relative movement of the two gripper fingers 53 and which can be designed, for example, as an electric or pneumatic drive device. Each of the gripper fingers 53 is provided with a piezo sensor on an inner surface 55, which is opposite the other gripper finger 53. This piezo sensor is identical to the piezo sensor 31, so that a more detailed description is unnecessary.Each of the piezo sensors 31 is connected via an associated sensor line 56 to an evaluation device 57, which is designed to evaluate the electrical signals of the piezo sensors 31 and which enables, for example, the determination of gripping forces or the determination of structure-borne sound events when the gripper fingers 53 impact objects (not shown). To protect the piezo sensors 31 and to ensure advantageous force transmission between the respective gripper finger 53 and the gripped object (not shown), each of the piezo sensors 31 is covered by a rubber layer 58.

[0039] In the Fig. 3 shows a sensor arrangement 71 not belonging to the invention, in which the measuring body is formed by a valve body 73 of a fluid-conducting component designed as a manually operable control valve and referred to as valve 72. A piezo sensor 81 is attached, for example, glued to a front side 74 of the valve body 73, which is purely exemplary and flat. For example, the piezo sensor 81 comprises a rectangularly cut piezoactive plastic film 82, which is provided with a strip-shaped metallization in certain regions on the front side facing the observer and on a rear side facing the valve body 73, thereby forming an upper electrode 83 and a lower electrode 84, shown only in dashed lines.The lower electrode 84 is connected to a contact pad 86 on the front side of the piezo sensor 81 via an electrical via (not shown in detail), so that both electrodes 83, 84 can be electrically contacted from the front side of the piezo sensor 81. Furthermore, a meandering resistance track, which can be used as a temperature sensor 87, is also applied to the front side as a metallic coating on the piezoactive plastic film 82, which has a contact pad at each of its opposite end regions. The temperature sensor 87 changes its electrical resistance depending on the temperature of the piezoactive plastic film 82 and can thus be used by an evaluation device 75 for temperature compensation of the signals from the two electrode arrangements 83, 84.For example, it can be provided that the evaluation device 75 is designed to detect structure-borne sound events on the fitting 72, such as can occur, for example, when the fitting 72 is flowed through by a fluid such as compressed air or water, as is indicated by the two lateral arrows in the . Fig. 3 is symbolized, or when an adjustment of the valve 72 is made on a handwheel 76.

Claims

[1] Sensor arrangement (1) for detecting deformation events, comprising a measuring body (3) having a surface that can be elastically deformed by external forces and / or by internal forces acting on the measuring body (3), and comprising a piezoelectric sensor (31) comprising a piezoactive plastic film (32) provided with at least two electrodes (33, 34) arranged at a distance from one another, and comprising a strain sensor (23) designed as a strain gauge for detecting a deformation of the measuring body (3); wherein the measuring body (3) is designed as an actuator housing of an actuator (2), wherein the actuator housing delimits a working chamber (4) in which a working element (5) is accommodated so as to be movable along a movement path (6) between a first functional position and a second functional position,wherein the working element (5) divides the working chamber (4) into a first variable-size working space (7) and a second variable-size working space (8), wherein the first working space (7) is assigned a fluid connection which is designed for ventilation and de-aeration of the first working space (7), wherein the piezo sensor (31) and the strain sensor (23) are accommodated in a sensor groove (12) of the actuator housing and are accommodated between the measuring body (3) and a pressure body (25) coupled to the measuring body (3), wherein the pressure body (25) has a pressure surface which is geometrically similar to the surface of the measuring body (3) provided with the piezo sensor (31) and / or the strain sensor (23), so that the piezo sensor (31) and / or the strain sensor (23) rests against the surface of the measuring body (3) in a force-fitting manner, in particular exclusively in a force-fitting manner. [2] Sensor arrangement (1) according to claim 1, characterized bythat the piezo sensor (31) is electrically connected to an evaluation device (43) which is designed to detect time-varying electrical charges of the piezoactive plastic film (32). [3] Sensor arrangement (1) according to claim 2, characterized by that the evaluation device (43) comprises a transimpedance amplifier, in particular designed as an operational amplifier, and is designed to evaluate signals from the piezo sensor (31) for structure-borne sound events and / or deformation events. [4] Sensor arrangement (1) according to claim 2 or 3, characterized by that the piezoactive plastic film (32) of the piezo sensor (31) is provided in some areas with a conductor track (87) which is electrically connected to the evaluation device (43), wherein the evaluation device (43) is designed to determine the temperature of the piezo sensor (31). [5] Sensor arrangement (1) according to one of the preceding claims, characterized bythat the strain sensor (23) is electrically connected to an evaluation device (43) and that the evaluation device (43) is designed to evaluate signals from the strain sensor (23) for deformation events. [6] Sensor arrangement (1) according to one of claims 2 to 5, characterized by that the evaluation device (43) is designed for a combined evaluation of signals from the piezo sensor (31) and / or the strain sensor (23) with the signals from the position sensor (24). [7] Sensor arrangement (1) according to one of claims 2 to 6, characterized by that the evaluation device (43) is designed to determine structure-borne sound events on the basis of sensor signals from the piezo sensor (31) and pressure change events on the basis of sensor signals from the strain sensor (23). [8] Sensor arrangement (1) according to one of the preceding claims, characterized bythat an insulating film (28) is arranged between the actuator housing (3) and the piezo sensor (31) and / or between the actuator housing (3) and the strain sensor (23), which is designed to be electrically conductive on one side, in particular as a copper-clad polyimide film, wherein an electrically conductive surface of the insulating film (28) faces the piezo sensor (31) and / or the strain sensor (23). [9] Sensor arrangement (1) according to claim 1, characterized by that the pressure body (25) is made of a rubber-elastic material which has, in particular, electrically conductive sections arranged at equal intervals, which are insulated from one another by electrically insulating sections and which are designed for an electrical connection of the piezo sensor (31) and / or the strain sensor (23). [10] Sensor arrangement (1) according to claim 9, characterized bythat the evaluation device (43) is formed on an electrical circuit board (41) which is provided on a largest surface with electrical conductor tracks (42) which rest at least partially on the electrically conductive sections of the pressure body (25). [11] Sensor arrangement (1) according to one of the preceding claims, characterized by that a position sensor (24) for detecting a position of an actuator element (5) arranged movably on or in the measuring body (3) is formed on the measuring body (3) and / or that the piezoactive plastic film (32) of the piezo sensor (31) is made of the material polyvinylidene fluoride.

Images