WO2021244815A1

WO2021244815A1 - Acceleration sensor and use of such an acceleration sensor

Info

Publication number: WO2021244815A1
Application number: PCT/EP2021/061698
Authority: WO
Inventors: Marco Laffranchi; David Weber; Tobias FROMMENWILER
Original assignee: Kistler Holding Ag
Priority date: 2020-06-02
Filing date: 2021-05-04
Publication date: 2021-12-09

Abstract

The invention relates to an acceleration sensor (10); which acceleration sensor (10), in order to measure accelerations of a measurement object (20), is able to be fastened to the measurement object (20); which acceleration sensor (10) has a housing (1), a carrier (2), at least one measurement element (3, 3') and at least one seismic mass (4, 4'); which housing (1) has a cavity (0); which carrier (2), which measurement element (3, 3') and which seismic mass (4, 4') are arranged in the cavity (0); wherein the measurement element (3, 3') and the seismic mass (4, 4') are attached to the carrier (2); wherein, when the acceleration sensor (10) is in a state fastened to the measurement object (20), accelerations of the measurement object (20) act on the seismic mass (4, 4'); which seismic mass (4, 4'), on account of its inertia, exerts forces on the measurement element (3, 3') under the effect of the accelerations of the measurement object (20); which measurement element (3, 3') generates measurement signals under the effect of the forces; wherein the housing (1) has a cutout (1.2), which carrier (2) has an outer end face (2.0) and extends through the cutout (1.2) with the outer end face (2.0); wherein, when the acceleration sensor (10) is in a state fastened to the measurement object (20), the carrier (2) is in contact with the measurement object (20) by way of the outer end face (2.0); wherein the carrier (2) has a modulus of elasticity greater than or equal to 350 GPa; and wherein the carrier (2) has a density less than or equal to 5 g/cm³.

Description

Accelerometer and use of such an accelerometer

Technical area

The invention relates to an acceleration sensor and a use of such an acceleration sensor according to the preamble of the independent claims.

State of the art

Accelerations of a measurement object are measured in many very different applications such as robotics, energy generation, transport, etc. Shocks and vibrations acting on the measurement object are measured as accelerations. The accelerations are given as a multiple of the acceleration due to gravity g = 9.81msec ² . Typical orders of magnitude of the accelerations are +/- 500g at measuring frequencies of 2Hz to 25kHz. An acceleration sensor is attached to the measurement object to measure the accelerations.

The document DE2817981A1 shows such an acceleration sensor. The acceleration sensor has a me-metallic housing, which consists of a base plate and a cover. The base plate and cover hermetically seal a cavity in the housing from outside the housing. A pin is formed on a top side of the base plate, around which pin several measuring elements and several seismic masses are arranged in the cavity. The measuring elements are piezoelectric measuring elements. The pin has three side faces surfaces that are twisted at an angle of 120 ° to each other. A measuring element is attached to each side surface. A seismic mass is assigned to each measuring element, and the seismic mass is attached to the measuring element. The seismic masses are arranged on outer surfaces of the measuring elements facing away from the side surfaces of the journal. This arrangement is held together by a ring spring. In the cavity, the annular spring rests against outer surfaces of the seismic masses facing away from the measuring elements. And on an underside of the base plate facing away from the top, an external thread is formed, via which the acceleration sensor can be attached to the measurement object. Accelerations of the measuring object act on the seismic masses via the housing and the journal and via the measuring elements. The seismic masses have an inertia. Due to their inertia, the seismic masses exert forces on the measuring elements. For each pairing of measuring element and assigned seismic mass, the forces act on the measuring element along a measuring axis from the seismic mass. The measuring element generates measuring signals under the effect of the forces. The measurement signals are proportional to the accelerations to be measured. The measurement signals are picked up via the ring spring and transferred to a plug in the cover. The measurement signals are derived from the connector via a signal cable to an evaluation unit. The tapping and the derivation of the measurement signals are electrically isolated from the housing.

The document EP059793A1 discloses an acceleration sensor with a solid metallic base plate, wel che in one piece with a likewise solidly made holding organ for a piezoelectric plate, a mass body and is an electrode. A sheet metal cap surrounds the holding element, the piezoelectric flap, the mass body and the electrode to protect against harmful environmental influences. The sheet metal cap is attached to the base plate via a free edge. The acceleration sensor is attached to the measurement object via the base plate.

The document DE2712359A1 also shows an acceleration sensor where a base plate carries a pin on which a piezoelectric element, a measuring mass and an electrode ring are attached on the outside. The pin, the piezoelectric element, the measuring mass and the electrode ring are firmly secured against each other and protected against external influences via a cap-shaped housing part. The cap-shaped housing part sits in a press fit on the base plate. The acceleration sensor is attached to the measurement object via the base plate.

[0006] Document US3858065A1 also describes an acceleration sensor with a metallic base plate, which base plate is integral with a web, which web in turn carries a piezoelectric crystal, electrodes and a seismic mass. A hollow cylindrical housing encloses the piezoelectric crystal, the electrodes and the seismic mass and is connected to the base plate. It is the base plate with which the acceleration sensor rests on the measurement object.

And then the document EP0762131A2 also shows an acceleration sensor in which the carrier is attached to a base plate, which carrier is a piezoelectric element, a seismic see ground and carries an electrical contact. A pot-shaped housing is attached to the outside of the base plate and protects the piezo element, the seismic mass and the electrical contact. The carrier and the base plate make contact with the measurement object.

Such an acceleration sensor should have a small structural dimension, because there is often little space available on the measurement object for fastening the acceleration sensor. A small structural dimension of less than 1 cm ³ is therefore desirable.

An acceleration sensor should also have a low weight. This is because the inertia of the acceleration sensor attached to the measurement object falsifies the acceleration of the measurement object to be measured. A low weight of less than 10g is therefore aimed for.

And then forces which do not originate from the accelerations to be measured and which, as interference forces, falsify the measurement of the accelerations, should be as small as possible.

- Interfering forces can be caused by thermally induced non-linearity of the acceleration sensor. The thermally induced non-linearity is the deviation of the proportionality between the measurement signals and the accelerations to be measured when the temperature changes. The thermally induced non-linearity falsifies the measurement of the acceleration of the measurement object. The thermally induced non-linearity can have various causes such as different thermal expansion coefficients of the measurement object and housing, etc. With different thermal output Expansion coefficients of the measuring object and the housing, mechanical stresses are generated in the housing, which can act as disruptive forces on the measuring elements. A thermally induced non-linearity of less than 3% over the entire operating temperature range is required for high measurement accuracy.

- Interfering forces can, however, also originate from cross-talk. Speaking transversely comes from force components that originate transversely to the measuring axis of a pairing of measuring element and assigned seismic mass. The force components acting across the measuring axis are disruptive forces. If a measuring element now also generates interference signals for such interference forces, one speaks of cross-talk.

- Finally, the housing can deform elastically under the accelerations. Movements of the signal cable can also cause elastic deformations of the housing. The elastic deformations of the housing lead to mechanical stresses, which act as interference forces on the measuring elements via the housing and can generate interference signals.

For a high measurement accuracy, a proportion of the interfering forces in the forces should be below 20%.

The object of the present invention is to provide an acceleration sensor which measures the accelerations to be measured with a high degree of accuracy while being small and lightweight. Presentation of the invention

This object is achieved by the acceleration sensor with the features of the first independent claim and with the use of an acceleration sensor with the features of the second independent claim.

The invention relates to an acceleration sensor; which acceleration sensor for measuring accelerations of a measurement object can be attached to the measurement object; which acceleration sensor has a housing, a carrier, at least one measuring element and at least one seismic mass; which housing has a cavity; which carrier, which measuring element and which seismic mass are arranged in the cavity; wherein the measuring element and the seismic mass are attached to the carrier; wherein when the acceleration sensor is attached to the measurement object, accelerations of the measurement object act on the seismic mass; which seismic mass exerts forces on the measuring element due to its inertia under the effect of the accelerations of the measuring object; which measuring element generates measuring signals under the effect of the forces; wherein the housing has a recess, which carrier has an outer recess and the outer end face extends through the recess; where, when the acceleration sensor is attached to the measurement object, the carrier is in contact with the measurement object via the outer end face; wherein the carrier has a modulus of elasticity of greater than or equal to 350GPa; and wherein the carrier has a density of less than / equal to 5 g / cm ³ . The invention also relates to a use of an acceleration sensor for measuring accelerations of a measurement object; which acceleration sensor is attached to the measurement object; which acceleration sensor has a housing, a carrier, at least one measuring element and at least one seismic mass; which housing has a cavity; which carrier, which measuring element and which seismic mass are arranged in the cavity; wherein the Mes selement and the seismic mass are attached to the carrier; accelerations of the measurement object acting on the seismic mass; which seismic mass exerts forces on the measuring element due to its inertia under the effect of the accelerations of the measuring object; which measuring element generates measuring signals under the effect of the forces; the housing having a recess, which carrier has an outer recess and the outer end face extends through the recess and is in contact with the measurement object via the outer end face; wherein the carrier has a modulus of elasticity of greater than or equal to 350GPa; and wherein the carrier has a density of less than / equal to 5 g / cm ³ .

In contrast to the prior art according to DE2817981A1, a carrier thus extends through a recess in the housing and is in contact with the measurement object. This has the advantage that the accelerations to be measured act on the measuring element and the seismic mass while avoiding the housing. The housing only has a protective function. It protects the measuring element and the seismic mass from harmful environmental influences. According to the invention, it is therefore not the housing that transmits the accelerations to be measured to the measuring element and the seismic mass. carries, but the carrier is intended for it. The housing and carrier therefore have a minimal interface. Interfering forces which falsify the measurement of the accelerations of the measurement object and which originate from the housing thus have a minimal interface to the measurement element and to the seismic mass. Such disruptive forces are thus effectively reduced.

In a further difference compared to the prior art according to the documents EP059793A1, DE2712359A1, US3858065A1 and EP0762131A2, the carrier according to the invention has a high resistance to elastic deformations due to the large modulus of elasticity, which elastic deformations in turn act as interfering forces on the measuring element and can generate spurious signals. The carrier is therefore very stiff and only deforms very slightly when accelerated. And thanks to its low density, the carrier is also extremely light. In particular, the carrier according to the invention is lighter than the metallic holding organs, pins, webs and carriers from the prior art, whereby the acceleration sensor has a comparatively higher resonance frequency, which expands the measuring range to high frequencies.

Advantageous embodiments of the acceleration sensor are defined in the dependent claims.

Brief description of the drawings

In the following, the invention is explained in more detail using an exemplary embodiment of an acceleration sensor with reference to the figures. Show it Fig. 1 is a view of part of the acceleration sensor; and

FIG. 2 shows a section along a line AA 'through the acceleration sensor from FIG. 1.

In principle, the same parts are provided with the same reference symbols in the figures.

Ways of Carrying Out the Invention

1 and 2 show an exemplary embodiment of an acceleration sensor 10 according to the invention.

The acceleration sensor 10 has a housing 1, a carrier 2, at least one measuring element 3, 3 'and at least one seismic mass 4, 4.

The housing 1 protects the measuring element 3, 3 'and the seismic mass 4, 4 from harmful environmental influences such as

Impurities (dust, moisture, etc.) and from electrical and electromagnetic interference in the form of electromagnetic radiation. The housing 1 is made of mechanically resistant material such as pure metals, nickel alloys, cobalt alloys, iron alloys, etc. In the game Ausführungsbei the housing 1 is made of titanium.

The housing 1 is a three-dimensional hollow body. In the exemplary embodiment, the housing 1 has along a Transverse axis X has a width of 6mm, along a longitudinal axis Y the housing 1 has a length of 6mm and along a vertical axis Z the housing 1 has a height of 5mm. In an XY plane spanned by the transverse axis X and the longitudinal axis Y, the housing 1 has a rectangular cross section of 36 mm ² . Overall, the housing 1 has a small external dimension of less than / equal to 180 mm ³ . With knowledge of the present invention, the person skilled in the art can also realize a housing for an acceleration sensor with other cross-sectional shapes, such as a circle, etc. A person skilled in the art can also implement an acceleration sensor with a smaller housing or with a larger housing.

The housing 1 has a lower part 1.1, a side wall 1.3 and an upper part 1.4. According to Fig. 2, the upper part 1.4 is arranged along the vertical axis Z above the lower part 1.1. Lower part 1.1, side wall 1.3 and upper part 1.4 can be taken in one piece or as individual parts gefer. In the exemplary embodiment, the lower part 1.1, the side wall 1.3 and the upper part 1.4 are individual parts that are firmly connected to one another.

The housing 1 has a housing surface 1.0. The housing surface 1.0 lies in a contact surface C spanned by the transverse axis X and the longitudinal axis Y. The housing 1 can be fastened in the contact surface C on the measurement object 20 via the housing surface 1.0. The housing surface 1.0 is preferably part of the lower part 1.1.

The housing 1 encloses a cavity 0. In the cavity 0, the carrier 2, the measuring element 3, 3 'and the seismic mass 4, 4 'arranged. The cavity 0 has a volume.

Because the housing 1 only has a protective function for the measuring element 3, 3 'and the seismic mass 4, 4, and that the housing 1, in a departure from the prior art according to DE2817981A1, the accelerations to be measured of the measurement object does not transfer to the measurement element 3, 3 ', the wall thickness of the housing 1 does not have to be so strong in order to suppress mechanical stresses that arise when the housing is fastened to the measurement object and act as disruptive forces on the housing. A wall thickness of the housing 1 is therefore weight-optimized, as a result of which the acceleration sensor 10 has a low weight of less than 10 g, which extends the measuring range to high frequencies. The wall thickness of the housing 1 is preferably less than or equal to 0.5mm. In the exemplary embodiment, the wall thickness of the housing is 10.25mm.

The housing 1 has a recess 1.2. Preferably, the recess 1.2 is arranged in the housing surface 1.0 to. The recess 1.2 lies like the housing surface 1.0 in the contact surface C. In the exemplary embodiment, the recess 1.2 has a width of 3 mm along the transverse axis X and the recess 1.2 has a length of 3 mm along the longitudinal axis Y. Thus, the recess 1.2 has an upper surface of 9mm ² . The housing surface 1.0 in turn has a width of 6 mm along the transverse axis X and a length of 6 mm along the longitudinal axis Y in the exemplary embodiment. The housing area 1.0 thus has a surface area of 27 mm ² . In the contact surface C, the recess 1.2 is completely radially surrounded by the housing surface 1.0. The recess 1.2 is preferably enclosed by the housing surface 1.0 by a rectangular, closed circumferential abutment surface 1.6. In the exemplary embodiment, the abutment surface 1.6 has a width of 3 mm along the transverse axis X, it has a length of 3 mm along the longitudinal axis Y and a wall thickness of 0.25 mm along the vertical axis Z. A surface of the joint area 1.6 is therefore 3.0mm ² .

The housing 1 has a through opening 1.8. In the exemplary embodiment, the through opening 1.8 is arranged in the upper part 1.4. With knowledge of the present invention, the through opening can also be arranged in the side wall.

The carrier 2 is advantageously made of mechanically stiff material of low density such as Al2O3, ceramic, Al20 ₃ ceramic, sapphire, etc. The carrier 2 is mechanically stiff in order to inelastically transmit accelerations to be detected to the seismic mass 4, 4 . The mechanically rigid carrier 2 has a high resistance to elastic deformations, which elastic deformations in turn act as interference forces on the measuring element 3, 3 'and can generate interference signals. For high mechanical rigidity, the material of the carrier 2 has a modulus of elasticity of greater than or equal to 350 GPa. The material of the carrier 2 preferably has a modulus of elasticity in the range from 350 GPa to 470 GPa. Due to the high mechanical rigidity, the carrier 2 can only deform very slightly during accelerations. For a low density, the material of the carrier gers 2 has a density of less than / equal to 5g / cm ³ . The material of the carrier 2 preferably has a density in the range from 4 g / cm ³ to 5 g / cm ³ . Due to the low density of the carrier 2 is easy. In particular, the carrier 2 is lighter than the metallic pin from the prior art according to DE2817981A1, as a result of which the acceleration sensor 10 has a comparatively higher resonance frequency, which extends the measuring range to high frequencies.

The carrier 2 is preferably a cube with two end faces and four side faces. The two end faces delimit the support 2 along the vertical axis Z, the four side faces delimit the support 2 along the transverse axis X and along the longitudinal axis Y. The two end faces comprise an outer end face 2.0 and an inner end face 2.0 '. The outer face 2.0 lies outside the cavity 0, the inner face 2.0 'lies in the cavity 0. The four side faces include a first side face 2.3, a second side face 2.3', a third side face 2.3 '' and a fourth side face 2.3 ''' . The end faces and side faces are largely the same size. In the embodiment, the carrier 2 has a width of 3 mm along the transverse axis X, the carrier 2 has a length of 3 mm along the longitudinal axis Y and the carrier 2 has a height of 3.5 mm along the vertical axis Z. Thus, each end face has a surface area of 9mm ² and each side surface has a surface area of 10.5mm ² . With knowledge of the present invention, the person skilled in the art can also realize a differently shaped carrier such as a multi-sided prism, a multi-sided pyramid, etc. The carrier 2 extends through the recess 1.2. Preferably, the carrier 2 extends with the outer end face 2.0 through the recess 1.2. The outer end face 2.0 lies in the contact area C. The carrier 2 can be fastened in the contact area C on the measurement object 20 via the outer end face 2.0.

The housing surface 1.0 and the outer end face 2.0 are thus in the same contact surface C. In the exemplary embodiment, the contact surface C is a flat surface. The surface of the housing surface 1.0 and the surface of the outer end face 2.0 form a surface of the contact surface C. In the exemplary embodiment, the surface of the contact surface is 36mm ² . With knowledge of the present invention, the person skilled in the art can also realize a differently shaped contact surface with steps, etc.

The acceleration sensor 10 can thus be fastened in the contact area C via the housing area 1.0 and via the outer end face 2.0 on the measurement object 20. The housing surface 1.0 is preferably larger than the outer end surface 2.0. In the exemplary embodiment, the housing surface 1.0 has a surface area of 27 mm ² and is three times larger than the outer end face 2.0 with a surface ^{area of 9 mm 2} .

The carrier 2 closes the recess 1.2. The four side surfaces 2.3, 2.3 ', 2.3'',2.3''' preferably lie precisely against the abutment surface 1.6 and thus form a precisely fitting closure of the recess 1.2. In the exemplary embodiment, the closure of the recess 1.2 has a fit with a play of less than 0.1mm. The carrier 2 is attached to the impact surface 1.6. In the exemplary embodiment, the four side surfaces 2.3, 2.3 ', 2.3 ", 2.3"''are attached to the abutment surface 1.6 by means of a material bond such as gluing, soldering, thermo-compression bonding, etc. The fastening of the carrier 2 to the abutment surface 1.6 closes the recess 1.2 hermetically tight to the outside of the housing 1. In the context of the invention, the expression "hermetically tight" means a gas-tight and pressure-tight closure of the recess 1.2 a leak test with gases such as helium or argon gas cannot be carried out and pressures of up to 2 bar can be permanently applied.

The carrier 2 is only in direct mechanical contact with the housing 1 in the area of the abutment surface 1.6. The surface of the abutment surface 1.6 is 3.0mm ² and is largely an order of magnitude smaller than the surface of the housing surface 1.0 with 27mm ² . The surface of the abutment surface 1.6 thus forms a minimal interface between the housing 1 and the carrier 2. This means that disruptive forces which originate from the housing 1 act less via the abutment surface 1.6 than rather via the housing surface 1.0. The disruptive forces act in a main force via the housing surface 1.0 into the measurement object 20 and they act in a largely an order of magnitude smaller shunt force via the impact surface 1.6 into the carrier 2. Therefore, the acceleration sensor 10 has a small proportion of the disruptive forces for high measurement accuracy the forces of less than 20%.

The fastening of the acceleration sensor 10 on the measurement object 20 takes place via a fastening means 9. Preferably, the fastening means 9 is a cohesive fastening means 9 and the acceleration sensor 10 is fastened to the measurement object 20 via material bonding such as gluing, thermocompression bonding, etc. In the exemplary embodiment, the material fastening means 9 largely completely covers the housing surface 1.0 and the end face 2.0. A thickness of the cohesive fastening means 9 along the vertical axis Z is less than / equal to 0.1 mm. The carrier 2 is in contact with the measurement object 20 due to the type of thin, cohesive fastening means 9. Such fastening of the acceleration sensor 10 to the measurement object 20 can be carried out quickly and inexpensively.

The cohesive fastening means 9 is a chemically curing adhesive or a physically settable adhesive or a combination of a chemically curing adhesive and a physically settable adhesive. The cohesive fastening means 9 preferably consists of an adhesive such as epoxy, polyurethane, cyanoacrylate, methyl methacrylate, etc.

In contrast to the prior art according to DE2817981A1, the acceleration sensor 10 is therefore not attached to the measurement object via a screw connection. Such screw connections lead to mechanical stresses which act as disruptive forces on the housing and falsify the measurement of the accelerations. The fastening of the acceleration sensor 10 via the integral fastening means 9, however, is free of mechanical stresses. The fastening of the acceleration sensor 10 via the integral fastening means 9 on the measurement object 20 is also largely inelastic. For high mechanical rigidity, the chemically cured adhesive or the physically set adhesive or a combination of a chemically cured adhesive and a physically set adhesive has a modulus of elasticity greater than or equal to IPA. The modulus of elasticity is preferably in the range from IGPa to IGPa.

The acceleration sensor 10 has at least one measuring element 3, 3 '. In the exemplary embodiment, the acceleration sensor 10 has a first measuring element 3 and a second measuring element 3 '. With knowledge of the present invention, the person skilled in the art can also implement an acceleration sensor with more than two measuring elements.

The measuring element 3, 3 'is attached to the carrier 2. The first measuring element 3 is preferably attached to the first side surface 2.3 and the second measuring element 3 'is attached to the third side surface 2.3'.

The measuring element 3, 3 'consists of piezoelectric material such as quartz (S1O2 single crystal), calcium gallo-germanate (Ca ₃ Ga2Ge40i4 or CGG), langasite (La ₃ Ga5SiOi4 or LGS), tourmaline, gallium orthophosphate, piezoceramics, etc. The measuring element 3, 3 'is rectangular in cross section with an upper surface of preferably less than 1 cm ² and with a thickness of preferably less than 2 mm.

The acceleration sensor 10 has at least one seismic mass 4, 4 '. In the exemplary embodiment, the Acceleration sensor 10 has a first seismic mass 4 and a second seismic mass 4 '. With knowledge of the present invention, those skilled in the art can also implement an acceleration sensor with more than two seismic masses.

The seismic mass 4, 4 'is attached to the measuring element 3, 3'. In the exemplary embodiment, the first seismic mass 4 is attached to the first measuring element 3 and the second seismic mass 4 'is attached to the second measuring element 3'. Accelerations of the measuring object 20 act from the measuring object 20 directly on the carrier 2 and from the carrier 2 indirectly via the measuring element 3, 3 'on the seismic mass 4, 4'.

The seismic mass 4, 4 'is made of material of high density such as iridium, platinum, tungsten, gold, etc. For small external dimensions of the acceleration sensor 10, the seismic mass 4, 4' has a high density of greater than 17g / cm ³ . The seismic mass 4, 4 ′ preferably has a high density of greater than 19 g / cm ³ . The seismic mass 4, 4 'is rectangular in cross section with a surface area of preferably less than 1 cm ² and with a thickness of preferably less than 5 mm. Due to the high density of the seismic mass 4, 4 ', the acceleration sensor 10 has a small structural dimension. In particular, a structural dimension of the acceleration sensor 10 is smaller than that of the acceleration sensor from the prior art according to DE2817981A1.

The fastening of the measuring element 3, 3 'on the carrier 2 and the fastening of the seismic mass 4, 4' on the measuring element 3, 3 'takes place by means of a material bond such as gluing, thermocompression bonding, etc. The accelerations of the measurement object 20 to be measured act on the seismic mass 4, 4 '. Under the effect of the accelerations of the measuring object 20, the seismic mass 4, 4 'exerts forces on the measuring element 3, 3' due to its inertia. The forces act as shear forces or as normal forces on the measuring element 3, 3 '.

Under the action of the forces, the measuring element 3, 3 'generates piezoelectric charges. A number of the piezoelectric charges is proportional to a magnitude of the forces, which magnitude of the forces is in turn proportional to a magnitude of the accelerations of the measurement object 20 to be measured. The piezoelectric charges are referred to below as measurement signals.

The measurement signals are generated on surfaces of the measuring element 3, 3 'and picked up by at least two electrodes 5 - 5' '' attached to surfaces of the measuring element 3, 3 '. In the exemplary embodiment, the first measuring element 3 has a first electrode 5 and a second electrode 5 ′ and the second measuring element 3 ′ has a third electrode 5 ″ and a fourth electrode 5 ″ ″.

The electrodes 5 - 5 '''are made of electrically conductive material such as copper, copper alloys, gold, gold alloys, aluminum, aluminum alloys, silver, silver alloys, etc. The electrodes 5 - 5''' can be therm - mock up with a metal foil or by depositing metal on the surfaces of the measuring element 3, 3 '. Each electrode 5 - 5 '''has a thickness of preferably less than 0.1 mm. The acceleration sensor 10 has signal conductors 6, 6 '. The signal conductors 6, 6 'are made of electrically conductive material such as copper, copper alloys, gold, gold alloys, aluminum, aluminum alloys, etc. Each signal conductor 6, 6' has a diameter of less than 1mm.

First signal conductors 6 derive the measurement signals from electrodes 5 - 5 '' 'to a converter unit 7. The first signal conductors 6 are attached to the ends of the electrodes 5 - 5 '' '. The first signal conductors 6 are attached to the ends of the electrodes 5 - 5 '' 'by material bonding such as wire bonding, soldering, etc. For wire bonding, methods such as thermocompression bonding, thermosonic ball wedge bonding, ultrasonic wedge wedge are suitable -Bond etc.

The transducer unit 7 is arranged on the inner end face 2.0 '. The first signal conductors 6 are attached to the converter unit 7. The first signal conductor 6 is attached to the transducer unit 7 by material bonding such as wire bonding, soldering, etc. In wire bonding, methods such as thermocompression bonding, thermosonic ball-wedge bonding, ultrasonic wedge-wedge bonding, etc. are suitable.

The converter unit 7 converts derived measurement signals. For this purpose, the converter unit 7 has electrical components. The electrical components can be attached directly to the inner end face 2.0 ', and / or the electrical components can be attached to an electrical circuit board, which electrical circuit board is then attached to the inner end face 2.0'. The electrical components are transimpedance converters, electrical resistors, electrical capacitors, etc. The converter unit 7 preferably filters the derived measurement signals with a high-pass filter, a low-pass filter, etc. For example, a high-pass filter can filter interference frequencies of the measurement signals below a lower limit frequency. And a low-pass filter can filter interference frequencies in the measurement signals above an upper limit frequency.

Second signal conductors 6 'derive converted measurement signals from the transducer 7 to an electrical feed-through 8. The second signal conductor 6 'are fastened to the converter unit 7 be. The second signal conductor 6 'is attached to the transducer unit 7 by means of a material bond such as wire bonding, soldering, etc. For wire bonding, methods such as thermocompression bonding, thermosonic ball wedge bonding, ultrasonic wedge wedge bonding, etc. are suitable.

The electrical bushing 8 has an Isolati onskbody 8.0 made of electrically insulating material such as Al2O3, ceramic, A ^ CU ceramic, sapphire, etc. on. Electrical conductors 8.1 are arranged in the insulation body 8.0. The second Sig nalleiter 6 'are taken fastened at the ends of the electrical conductor 8.1. The attachment of the second signal conductor 6 'to the ends of the electrical conductor 8.1 takes place by material connection such as wire bonding, soldering, etc. In wire bonding, methods such as thermocompression bonding, thermosonic ball-wedge bonding, ultrasonic wedge-wedge bonding, etc. are suitable. The electrical conductors 8.1 conduct the measurement signals to the outside of the housing 1. The electrical bushing 8 closes the through opening 1.8 of the housing 1. In the exemplary embodiment, the electrical bushing 8 is attached to an edge of the through opening 1.8 of the housing 1 by means of a material bond such as gluing, soldering, thermocompression bonding, etc. The closure of the through opening 1.8 through the electrical bushing 8 and the fastening of the electrical bushing 8 on the housing 1 is hermetically sealed to the outside of the housing 1.

The housing 1 is preferably electrically conductive. The carrier 2 is preferably coated in an electrically conductive manner. The outer end face 2.0 of the carrier 2 is preferably coated in an electrically conductive manner. The electrically conductive coating can be formed by thermal lamination with a metal foil or by depositing metal. As the metal, copper, copper alloys, gold, gold alloys, aluminum, aluminum alloys, silver, silver alloys, etc. can be used. The electrically conductive coating has a thickness of preferably less than 0.01 mm. Preferably, the integral fastening means 9 is electrically lei tend. In this way, the housing 1 with the carrier 2 or the housing 2 with the outer end face 2.0 or the housing 1 with the integral fastening means 9 form a Faraday cage. Thus, the measuring element 3, 3 ', the electrodes 5, 5', the signal conductors 6, 6 and the converter unit 7 are effectively protected against electrical and electromagnetic interference effects in the form of static and quasi-static fields, electromagnetic waves, etc. Such electromagnetic interference can falsify a derivation of the measurement signals. The housing is preferably 1 electrically connected to a ground from the environment. Preferably, the housing 1 is electrically connected to a ground from the environment via an electrical connector that can be connected to the electrical bushing 8.

List of reference symbols

AA 'line

C contact area

X transverse axis

Y longitudinal axis

XY plane

Z vertical axis

0 cavity

1 housing

1.0 Housing surface 1.1 Lower part 1.2 Recess

1.3 side wall

1.4 Upper part 1.6 Joint area 1.8 Through opening 2 beams

2.0, 2.0 'face

2.3 - 2.3 "'side surface

3, 3 'measuring element

4, 4 'seismic mass

5 - 5 "'electrode

6 6 signal conductors

7 converter unit

8 electrical feedthrough

8.0 Insulation body 8.1 electrical conductors 9 fasteners

10 accelerometer

20 target

Claims

1. acceleration sensor (10); which acceleration sensor (10) can be attached to the measurement object (20) for measuring accelerations of a measurement object (20); which Be acceleration sensor (10) has a housing (1), a carrier (2), at least one measuring element (3, 3 ') and at least egg ne seismic mass (4, 4'); which housing (1) has a cavity (0); which carrier (2), which measuring element (3, 3 ') and which seismic mass (4, 4') are arranged in the cavity (0); wherein the measuring element (3, 3 ') and the seismic mass (4, 4') are attached to the carrier (2); wherein when the acceleration sensor (10) is attached to the measurement object (20), accelerations of the measurement object (20) act on the seismic mass (4, 4 '); which seismic mass (4, 4 ') exerts forces on the measuring element (3, 3') due to its inertia under the effect of the accelerations of the measuring object (20); which

Measuring element (3, 3 ') generated under the action of the forces Messsig signals; which housing (1) has a recess (1.2), which carrier (2) has an outer end face (2.0) and extends with the outer end face (2.0) through the recess (1.2); and wherein when the acceleration sensor (10) is attached to the measurement object (20), the carrier (2) is in contact with the measurement object (20) via the outer end face (2.0); characterized in that the carrier (2) has a modulus of elasticity of greater than or equal to 350 GPa; and that the carrier (2) has a density of less than / equal to 5 g / cm ³ . 2. acceleration sensor (10) according to claim 1, characterized in that the housing (1) has a housing surface (1.0); that the recess (1.2) is in the housing surface (1.0); and that the recess (1.

2) is completely enclosed in the housing surface (1.0) by an abutment surface (1.6) of the housing (1).

3. acceleration sensor (10) according to claim 2, characterized in that the carrier (2) closes the recess (1.2) with an accurate fit; that the carrier (2) is attached to the impact surface (1.6); and that the attachment of the carrier (2) to the abutment surface (1.6) hermetically seals the recess (1.2).

4. acceleration sensor (10) according to claim 3, characterized in that the carrier (2) is in mechanical contact with the housing (1) only in the area of the abutment surface (1.6); and that a surface of the impact surface (1.6) is largely an order of magnitude smaller than a surface of the housing surface (1.0).

5. acceleration sensor (10) according to claim 4, characterized in that because the surface of the impact surface (1.6) is largely an order of magnitude smaller than the surface of the housing surface (1.0) then also interference forces which are attached to the measurement object (20) State of the acceleration sensor (10) originate from the housing (1), act in a main force connection via the housing surface (1.0) in the measurement object (20) and in a largely an order of magnitude smaller force shunt via the impact surface (1.6) in the carrier (2 ) works.

6. acceleration sensor (10) according to any one of claims 1 to

5, characterized in that the carrier (2) is made of A10 ₃ or ceramic or A ^ Cp ceramic or sapphire.

7. acceleration sensor (10) according to any one of claims 1 to

6, characterized in that the measuring element (3, 3 ') consists of piezoelectric material; that the seismic mass (4, 4 ') exerts shear forces or normal forces on the measuring element (3, 3') due to its inertia under the action of the accelerations of the measuring object (20).

8. acceleration sensor (10) according to any one of claims 1 to

7, characterized in that the carrier (2) has an inner end face (2.0 '); that a transducer unit (7) is arranged on the inner end face (2.0 '); that first signal conductors (6) derive measurement signals from the measurement element (3, 3 ') to the converter unit (7); and that the converter unit (7) converts the derived measurement signals.

9. acceleration sensor (10) according to one of claims 1 to

8, characterized in that it is the seismic mass

(4, 4 ') has a high density of greater than / equal to 17 g / cm ³ .

10. Acceleration sensor (10) according to one of claims 1 to 9, characterized in that the housing (1) with the carrier (2) or the housing (2) with the outer end face (2.0) or the housing (1) with a Cohesive fastening means (9) of the acceleration sensor (10) on the measurement object (20) forms a Faraday cage.

11. Use of an acceleration sensor (10) for measuring accelerations of a measurement object (20); which Be acceleration sensor (10) is attached to the measurement object (20); which acceleration sensor (10) has a housing (1), a carrier (2), at least one measuring element (3, 3 ') and at least one seismic mass (4, 4'); which housing (1) has a cavity (0); which carrier (2), which measuring element (3, 3 ') and which seismic

Masses (4, 4 ') are arranged in the cavity (0); where the

Measuring element (3, 3 ') and the seismic mass (4, 4') on the

Carriers (2) are attached; accelerations of the measurement object (20) acting on the seismic mass (4, 4 '); which seismic mass (4, 4 ') exerts forces on the measuring element (3, 3') due to its inertia under the effect of the accelerations of the measuring object (20); which

Measuring element (3, 3 ') generated under the action of the forces Messsig signals; which housing (1) has a recess (1.2), which carrier (2) has an outer recess (2.0) and extends with the outer end face (2.0) through the recess (1.2) and via the outer end face (2.0) in contact with the measurement object (20) is characterized in that the carrier (2) has a modulus of elasticity of greater than / equal to 350 GPa; and that the carrier (2) has a density of less than / equal to 5 g / cm ³ .

12. Use of the acceleration sensor (10) according to claim 11, characterized in that the housing (1) has a housing surface (1.0); that the recess (1.2) lies in the housing surface (1.0), that the housing surface (1.0) and the outer end face (2.0) lie in a contact surface (C); and that the housing (1) and the carrier (2) in the contact surface (C) are in flat contact with the measurement object (20).

13. Use of the acceleration sensor (10) according to claim 12, characterized in that the acceleration sensor (10) is fastened to the measurement object (20) via a fastening means (9); that the fastening means (0) is a cohesive fastening means (9); and that the fastening means (9) Be the housing surface (1.0) and the outer end face (2.0) largely completely covered.