Sensor arrangement for detecting deformation events

Abstract

The invention relates to a sensor arrangement (1; 51; 71) for detecting deformation events, comprising a measuring body (3; 53; 73), and a piezoelectric sensor (31; 81) comprising a piezoactive plastic film (32; 82), in particular made of polyvinylidene fluoride, which is provided with at least two spaced-apart electrodes, or with at least two sensors from the group: piezoelectric sensor (31; 81) comprising a piezoactive plastic film (32; 82), in particular made of polyvinylidene fluoride, which is provided with at least two spaced-apart electrodes (33, 34; 83, 84), strain sensor (23) designed as a strain gauge for detecting a deformation of the measuring body (3; 53; 73), position sensor (24) designed for detecting a position of a device movably arranged on or in the measuring body (3; 53; 73). actuator element (5) is formed.

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

[0004] This object is achieved with a sensor arrangement of the type mentioned at the outset in that the sensor arrangement comprises a measuring body which has a surface which can be elastically deformed by external forces and / or by internal forces acting on the measuring body, and further comprises a piezosensor which has a piezoactive plastic film, in particular made of the material polyvinylidene fluoride, wherein the piezoactive plastic film is provided with at least two electrodes arranged at a distance from one another, in particular for tapping the electrical voltage from the plastic film or for measuring the current on the plastic film, or in that the sensor arrangement, in addition to the measuring body, is provided with at least two sensors from the group: piezosensor which has a piezoactive plastic film made of the material polyvinylidene fluoride, wherein the piezoactive plastic film is provided with at least two electrodes arranged at a distance from one another,in particular for tapping the electrical voltage from the plastic film or for measuring the current on the plastic film; a strain sensor designed as a strain gauge for detecting a deformation of the measuring body; a position sensor designed to detect a position of an actuator element movably arranged on or in the measuring body.

[0005] The measuring body is the component whose condition is to be monitored with the aid of associated sensors. In a first embodiment, a piezo sensor is associated with the measuring body. The sensor comprises 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 aid of such a piezo sensor, which is preferably pressed against the measuring body or can be integrally connected to the measuring body, an electrical charge change is provided as a function of a deformation of the measuring body and / or as a function of vibrations of the measuring body. This change can be converted into a status signal for the measuring body by a suitable evaluation device. In a further embodiment, combinations of sensors are provided which comprise a piezo sensor, a strain sensor, and a position sensor, with at least two sensors from the aforementioned group being arranged on the measuring body. The strain sensor can be used in the same way as the piezo sensor to detect elastic or elastic and plastic deformations of the measuring body.The position sensor is of interest when an actuator element is movably mounted on or in the measuring body, the relative position of which is to be determined. By combining the sensor signals from the sensors in the aforementioned group, useful information about the state of the measuring body can be obtained, particularly in the form of an observer, i.e., a virtual sensor.

[0006] Advantageous further developments of the invention are the subject of the subclaims.

[0007] It is advantageous if the piezo sensor and / or the strain sensor is 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 way that, on the one hand, ensures the transfer of deformations from the measuring body to the piezo sensor and / or the strain sensor and, on the other hand, does not require the creation of a material connection between the measuring body and the piezo sensor and / or the strain sensor, which is particularly advantageous when retrofitting the sensors to a measuring body.

[0008] The pressure body is preferably made of a material with high elasticity, for example a rubber-elastic material, in order to ensure an advantageous and uniform force introduction onto the sensors.

[0009] In a further development of the invention, the position sensor is designed as a pressure body. In this embodiment, the position sensor, which is usually housed in a dimensionally stable housing, can exert the pressure force on the other sensors. Preferably, an elastic intermediate layer is arranged between the position sensor and the piezo sensor and / or strain sensor.

[0010] In a further embodiment of 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.

[0011] It is advantageous if the measuring body is designed as a gripper finger of a gripper and is movably mounted on a gripper housing of the gripper. This design variant makes it possible, in particular, to determine the gripping force exerted by the gripper fingers on an object to be grasped.

[0012] Alternatively, it is provided that the measuring body is designed as a housing of a fluid-conducting component. In this embodiment, a statement can be made, in particular, about an operating state of the fluid-conducting component, which can be, purely by way of example, a fitting or a pneumatic control valve, in particular a switching valve or a proportional valve. In this case, structure-borne sound events caused, for example, by a fluid flow in the fluid-conducting component, which can preferably be detected using the piezo sensor, are evaluated. From this, a setting of the fluid-conducting component (closed, partially open, fully open) and / or a wear state of the fluid-conducting component can be determined, if necessary.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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 the 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 second embodiment of a sensor arrangement 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 third embodiment of a sensor arrangement 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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 with a metallic coating on both sides, 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In addition to the temperature sensor 22, the strain sensor 23, and the piezo sensor 31, the sensor group 21 includes a position sensor 24, which can be designed, in particular, as an inductive position sensor or a Hall position sensor and is designed to detect the position of the working piston 5 in the respective end region of the actuator housing 3. For example, the position sensor 24 is provided with 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.

[0032] 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.

[0033] In the Fig. In the second embodiment of a sensor arrangement, shown only schematically in Figure 2, gripper fingers 53 movable in opposite directions 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 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 detailed description is omitted.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.

[0034] In the Fig. 3 shows a third embodiment of a sensor arrangement 71. 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 a 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; 51; 71) for detecting deformation events, with a measuring body (3; 53; 73) which has a surface which can be elastically deformed by external forces and / or by internal forces acting on the measuring body (3; 53; 73), and with a piezosensor (31; 81) which has a piezoactive plastic film (32; 82), in particular made of the material polyvinylidene fluoride, wherein the piezoactive plastic film (32; 82) is provided with at least two electrodes arranged at a distance from one another, in particular for tapping an electrical voltage from the piezoactive plastic film (32; 82) or for measuring a current at the plastic film (32; 82), or with at least two sensors from the group: piezosensor (31; 81) which has a piezoactive plastic film (32; 82), in particular made of the material polyvinylidene fluoride, wherein the piezoactive plastic film (32;82) is provided with at least two electrodes (33, 34; 83, 84) arranged at a distance from one another, in particular for tapping an electrical voltage from the piezoactive plastic film (32; 82) or for measuring a current on the plastic film (32; 82); strain sensor (23) designed as a strain gauge for detecting a deformation of the measuring body (3; 53; 73); position sensor (24) designed to detect a position of an actuator element (5) arranged movably on or in the measuring body (3; 53; 73); [2] Sensor arrangement (1; 51; 71) according to claim 1, characterized byin that the piezo sensor (31; 81) and / or the strain sensor (23) is accommodated between the measuring body (3; 53; 73) and a pressure body (25) coupled to the measuring body (3; 53; 73), wherein the pressure body (25) has a pressure surface which is geometrically similar to the surface of the measuring body (3; 53; 73) provided with the piezo sensor (31; 81) and / or the strain sensor (23), so that the piezo sensor (31; 81) and / or the strain sensor (23) rests against the surface of the measuring body (3; 53; 73) in a force-fitting manner, in particular exclusively in a force-fitting manner. [3] Sensor arrangement (1; 51; 71) according to claim 2, characterized by that the position sensor (24) is designed as a pressure body. [4] Sensor arrangement (1; 51; 71) according to claim 1, 2 or 3, characterized byin that the measuring body (3; 53; 73) is designed as an actuator housing (3) of an actuator (2), wherein the actuator housing (3) 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 working space (7) of variable size and into a second working space (8) of variable size, wherein the first working space (7) is assigned a fluid connection which is designed for ventilating and de-ventilating the first working space (7). [5] Sensor arrangement (1; 51; 71) according to claim 1, 2 or 3, characterized by that the measuring body (3; 53; 73) is designed as a gripping finger (53) of a gripper (52) and is movably received on a gripper housing (54) of the gripper (52). [6] Sensor arrangement (1; 51; 71) according to claim 1, 2 or 3, characterized bythat the measuring body (3; 53; 73) is designed as a housing of a fluid-conducting fitting (72). [7] Sensor arrangement (1; 51; 71) according to one of the preceding claims, characterized by that the piezo sensor (31; 81) is electrically connected, in particular via a two-wire connection, to an evaluation device (43; 57; 75) which is designed to detect time-varying electrical charges of the piezoactive plastic film (32; 82). [8] Sensor arrangement (1; 51; 71) according to claim 7, characterized by that the evaluation device (43; 57; 75) comprises a transimpedance amplifier, in particular designed as an operational amplifier, and is designed to evaluate signals from the piezo sensor (31; 81) for structure-borne sound events and / or deformation events. [9] Sensor arrangement (1; 51; 71) according to claim 7 or 8, characterized bythat the piezoactive plastic film (32; 82) of the piezo sensor (31; 81) is provided in some regions with a conductor track (87), in particular one of a meandering shape, which is electrically connected to the evaluation device (43; 57; 75), wherein the evaluation device (43; 57; 75) is designed to determine the temperature of the piezo sensor (31; 81). [10] Sensor arrangement (1; 51; 71) according to one of the preceding claims, characterized by that the strain sensor (23) is electrically connected, in particular via a four-wire connection, to an evaluation device (43; 57; 75) and that the evaluation device (43; 57; 75) is designed to evaluate signals from the strain sensor (23) for deformation events. [11] Sensor arrangement (1; 51; 71) according to one of claims 7 to 10, characterized bythat the evaluation device (43; 57; 75) is designed for a combined evaluation of signals from the piezo sensor (31; 81) and / or the strain sensor (23) with the signals from the position sensor (24). [12] Sensor arrangement (1; 51; 71) according to one of claims 7 to 11, characterized by that the evaluation device (43; 57; 75) is designed to determine structure-borne sound events on the basis of sensor signals from the piezo sensor (31; 81) and pressure change events on the basis of sensor signals from the strain sensor (23). [13] Sensor arrangement (1; 51; 71) 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; 81) 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; 81) and / or the strain sensor (23). [14] Sensor arrangement (1; 51; 71) according to one of the preceding claims in conjunction with claim 2, characterized by in 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; 81) and / or the strain sensor (23). [15] Sensor arrangement (1; 51; 71) according to claim 14, characterized bythat the evaluation device (43; 57; 75) 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).

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