DE102020106427A1 - Force sensor system with overload protection - Google Patents

Abstract

The invention relates to a force sensor system (10), comprising - a housing arrangement (12) with at least one through recess (14) which has at least one diameter (D1) to accommodate at least one force measuring sensor (16), - at least one force measuring sensor (16), which is arranged in the at least one through recess (14); and- at least one abutment body (18) which is arranged in the at least one through recess (14), the force sensor system (10) having radial play (RS) between the at least one abutment body (18) and the through recess (14) an accurate force sensor system (10) with overload protection.

Description

The invention relates to a force-detecting sensor system with overload protection.

It has been found that in the off-highway machine sector, which includes agricultural and construction machinery, and in the trailer sector, there is a constant need for a force sensor system in order to precisely measure forces under, in some cases, widely differing conditions.

So far, there have been problems for force sensor systems when the measuring range and the overload range are so far apart that a conventional force measuring sensor fails in the event of an overload or only measures forces imprecisely.

In the off-highway sector in particular, machines must be designed to be very robust in order to withstand extreme loads undamaged. The wheel bearing forces of a construction machine can be cited as an example. In the case of a wheel loader, for example, the weight in the shovel can be determined. For example, three tons of material can be transported in its shovel. For a wheel loader with an unladen weight of around thirteen tons, this means that there are around four tons of weight per wheel. This value can be assumed as the nominal load for which the force sensor system is to be designed in order to record the weight of the conveyed material in the shovel as precisely as possible. In the operation of wheel loaders, however, there are situations in which the load is unevenly distributed on the wheels. For example, when eighty percent of the total weight is on a bike due to driving maneuvers. This corresponds to about thirteen tons or more than three times the original design. If the force sensor system is designed in such a way that it has a good measurement accuracy for the four-tonne nominal load, it would be destroyed in the event of an overload. If the force sensor system is designed in such a way that it can withstand the overload without damage, the measurement accuracy at the aforementioned nominal load is significantly reduced.

It is therefore the object of the invention to create a force sensor system that is accurate to measure and has overload protection.

The object is therefore achieved by a force sensor system, a housing arrangement and a force measuring sensor with the features of the independent claims. Preferred embodiments of the invention are specified in the subclaims and the following description, which can each represent an aspect of the invention individually or in combination.

The invention thus relates to a force sensor system
a housing arrangement with at least one through recess which has at least one diameter to accommodate at least one force measuring sensor;
at least one force measuring sensor which is arranged in the at least one through recess; and
at least one abutment body which is arranged in the at least one through recess, the force sensor system having radial play between the at least one abutment body and the through recess.

A basic idea of the invention and individual aspects of the claimed subject matter of the invention are explained below and preferred modified embodiments of the invention are described further below. Explanations, in particular regarding advantages and definitions of features, are basically descriptive and preferred, but not limiting, examples. If an explanation is limiting, this is expressly mentioned.

A basic idea of the invention is therefore that, as a result of the claimed construction of the force sensor system, the radial play is closed from a defined load and the forces are diverted around the force measuring sensor. This is also known as a force shunt. In particular, this force shunt should only come into operation outside of the measuring range in order not to falsify the measurement result or to maintain the measurement accuracy. The force shunt is achieved by bridging the play, i.e. a small gap. Since only very small distances or deformations occur during strain measurements, precisely manufactured machine components are required. Depending on the amount of play and the material properties, it can be set or defined from which force, tension and / or elongation a material deformation leads to a closed gap and thus the force shunt is formed.

The abutment body thus forms, with the defined gap, a radial play in relation to the housing arrangement. This radial play can be generated, for example, by precisely producing the through recess, for example by means of a grinding process. Then the diameter of the passage recess is measured and then the appropriate abutment body is selected and inserted. If a load that acts on the housing arrangement now exceeds a defined level, the play or the gap is closed and part of the force is diverted around the force measuring sensor.

For the purposes of the invention, radial play is at least one such gap which has a material distance between the inner surface of the through recess and the outer surface of the abutment body at a certain point in such a way that there is no force shunt for the regular force detection of a force sensor system set to a certain value range.

For example, a second abutment body can be placed in the housing arrangement in such a way that the second abutment body adjusts the housing deformation for the desired data acquisition through a correspondingly acting abutment. Additionally or alternatively, the housing arrangement can be constructed with through openings and / or grooves in such a way that the through openings and / or grooves adjust the housing deformation for the desired data acquisition through a corresponding weakening of the material. These measures can be advantageous in order to be able to use the housing arrangement for different force levels and / or to bring about an increase in force at selected points.

According to a preferred embodiment of the invention it is provided that the at least one through recess has at least two different diameters, namely a small diameter and a larger diameter;
the at least one force measuring sensor in the at least one
Through recess is arranged in the area of the small diameter; and the at least one abutment body in the at least one
The passage recess is arranged in the area of the larger diameter, the force sensor system having the radial play between the at least one abutment body and the passage recess in the area of the larger diameter. The different diameters ensure that the abutment body and the force measuring sensor do not touch. This is useful in order to keep the measuring accuracy of the force measuring sensor high. In particular, if the force measuring sensor has sensory means in the potential contact area, this can reduce the risk of false detections.

According to a preferred embodiment of the invention it is provided that one or more force measuring sensors is or are strain gauges, preferably glued or sputtered, and / or essentially has or have a cylindrical shape with at least one end face and / or a lateral surface, the at least one end face and / or the lateral surface have elongation means running in a meandering shape.

A strain gauge is a sensor that is used to measure the elongation of an object. The most common type of strain gauge consists of an insulating flexible pad that carries a metal foil pattern. The strain gauge is attached with a suitable adhesive, such as. B. cyanoacrylate, attached to the object. It is also possible to sputter the strain gauge onto the object to be detected. When the object is deformed, the film is deformed, which changes its electrical resistance. This change in resistance, which is usually measured with a Wheatstone bridge, is related to the elongation caused by the quantity known as the elongation factor. A strain gauge uses the physical property of electrical conductivity and its dependence on the geometry of the conductor. When an electrical conductor is stretched within the limits of its elasticity so that it does not break or permanently deform, it becomes narrower and longer, which increases its electrical resistance from end to end. Conversely, when a conductor is compressed so that it is not kinked, it widens and shortens, reducing its electrical resistance from end to end. The level of the induced voltage can be deduced from the measured electrical resistance of the strain gauge. A typical strain gauge arranges a long, thin conductive strip in a meandering shape, a zigzag pattern of parallel lines. This does not increase the sensitivity, since the percentage change in resistance for a given elongation is the same for the entire zigzag line as for a single conductor track. A single linear conductor would have to be extremely thin, which could cause it to overheat. This would change its resistance and it would expand. Or the track would have to operate at a much lower voltage, which would make it difficult to accurately measure changes in resistance.

Sputtering, also known as cathode atomization, is a physical process in which atoms are released from a solid body, also known as a target, by bombarding them with high-energy ions, predominantly noble gas ions, and then change into the gas phase.

A force measuring sensor, which essentially has a cylindrical shape with at least one end face and / or a lateral surface, the at least one end face and / or the lateral surface having meandering expansion means, is a force measuring sensor that is based on thin-film sensor technology and that does Uses the measuring method of strain gauges. The stretching means directly on the face and for temperature compensation also on the are exemplary and not limiting Coated outer surface of a small steel cylinder. The force measuring sensor is pressed into the through recess of the housing arrangement with a slight oversize and thus experiences the same expansion as the surrounding material. The thin-film sensor technology functionality is usually realized by a submicrometer-thin, stretch-sensitive metal coating that is structured by micromachining. This measuring structure enables a continuous force and torque measurement during operation. This measurement technology makes it possible, for example, to determine torque very quickly and precisely. In particular, it is a multi-layer system comprising an insulation coating and a stretch-sensitive metal coating, in particular by means of the PVD process, physical vapor deposition process. In contrast to chemical vapor deposition processes, physical processes are used to convert the starting material into the gas phase. The gaseous material is then fed to the substrate to be coated, where it condenses and forms the target layer. Particularly preferred for good measurement results, but not limiting, the essentially cylindrical shape of the force measuring sensor is a bolt, preferably with a diameter of eight millimeters and, for example, a length of twenty millimeters. In this context, essentially means that the cylindrical basic structure can partially have deviations, for example small recesses. A completely cylindrical shape is also possible.

According to a preferred embodiment of the invention it is provided that one or more abutment bodies are rolling bodies. Rolling bodies are known, for example, from rolling bearings as balls, rollers, cylindrical rollers, needles, cones or other rotating bodies made of steel, ceramic or special, extra hard plastics, which, as elements of a rolling bearing or a linear roller guide, significantly reduce the friction between the various components of the bearing or the guide reduce and thus extremely facilitate the relative movement of different machine elements to each other. Because of the completely different form of application, it is therefore far away to resort to rolling elements. It has been found that rolling bodies are particularly suitable as abutment bodies, since high-precision manufacturing processes for rolling bodies exist and the radial gap can thus be optimally adjusted. In particular, the rolling elements can be made of chrome steel. This material is very hard, but easily rusts, compared to the preferred steel grade 100Cr6; a steel with a content of about one percent by weight carbon and about one and a half percent by weight chromium. Other steels are, for example, 100CrMnSi6-4 and 100CrMo7, with the alloying elements manganese and molybdenum serving to improve hardenability. Because of the susceptibility to rust, the use of a cover element is particularly preferred. The high-alloy steels X65Cr13 and X30CrMoN15-1 can also be used for applications in a corrosive environment.

According to a preferred embodiment of the invention, it is provided that the at least one through recess between at least one force measuring sensor and at least one abutment body has a spacing device in order to abut the abutment body in a load-free manner relative to the force measuring sensor. For example, it can be provided that the at least one through recess in the transition area from a larger diameter to a small diameter has a step as a spacer device in order to counter the abutment body. The purpose of this feature is that the measuring accuracy of the force measuring sensor is not impaired.

According to a preferred embodiment of the invention it is provided that the at least one through recess has a cover element at one or both ends, which is preferably designed in two stages such that an inner diameter segment engages in the diameter, preferably the larger diameter, of the through recess and that a Even larger diameter outer diameter segment rests on an outer surface of the housing arrangement. Thus, on the one hand, it can be ensured that the abutment body does not fall out of the through recess. In addition, no dirt can penetrate into the passage recess. The cover element can be connected non-positively and / or positively, and in particular releasably, to the housing arrangement in order to always be able to access the force measuring sensor and / or the abutment body.

According to a preferred embodiment of the invention it is provided that the housing arrangement has one or more through openings and / or one or more grooves in order to be connected to a component via this or these and / or to set a flow of force for force detection via this or them . On the one hand, the housing arrangement must be connected to the component to be tested. A connection via one or more through openings and / or one or more grooves does not adversely affect the measurement result. On the other hand, the force flows can also be adjusted via the position of the connection between these components, so that the measurement quality can be improved and overload protection can be achieved.

According to a preferred embodiment of the invention it is provided that
the force sensor system has at least two abutment bodies in a through recess,
which are preferably arranged opposite one another along the through recess, and / or
which in particular surround the force measuring sensor along the passage recess at one end each. Deformations in two mutually opposite directions can thus be compensated for by the respective other abutment body. This increases the robustness and thus the measurement quality of the force sensor system.

The invention further relates to a housing arrangement for a force sensor system according to at least one of the preceding features, characterized by the features of the housing arrangement according to at least one of the preceding features.

The housing arrangement is preferably designed in the shape of a cuboid. It has been found that the aforementioned features can be implemented particularly well in the case of a cuboid shape. However, other shapes for the housing arrangement are also possible.

The invention further relates to a force measuring sensor for a force sensor system according to at least one of the preceding features, characterized by the features of the force measuring sensor according to at least one of the preceding features.

• 1: einen Längsschnitt durch ein Kraftsensorsystem gemäß einer ersten bevorzugten Ausführungsform der Erfindung, mit einer Gehäuseanordnung, einem Kraftmesssensor und einem Widerlagerkörper, wobei im Bereich des Widerlagerkörpers eine Belastung auf die Gehäuseanordnung wirkt;
• 2: einen Längsschnitt durch ein Kraftsensorsystem gemäß einer alternativen bevorzugten Ausführungsform der Erfindung, wobei das Kraftsensorsystem gegenüber 1 einen weiteren Widerlagerkörper aufweist, und mit einer andere Belastung beaufschlagt wird, die jeweils im Bereich des Widerlagerkörpers auf die Gehäuseanordnung wirkt;
• 3: eine perspektivische Ansicht eines Längsschnitts des Kraftsensorsystems gemäß der ersten bevorzugten Ausführungsform der Erfindung;
• 4: eine perspektivische Ansicht des gesamten Kraftsensorsystems gemäß der ersten bevorzugten Ausführungsform der Erfindung;
• 5: eine symbolische Detailansicht des Längsschnitts des Kraftsensorsystems gemäß der ersten bevorzugten Ausführungsform der Erfindung im Bereich des Widerlagerkörpers;
• 6: eine perspektivische Ansicht des Kraftsensorsystems gemäß der ersten bevorzugten Ausführungsform der Erfindung, montiert zwischen zwei Bauteilen;
• 7: mehrere Ansichten von Kraftsensorsystemen gemäß unterschiedlichen bevorzugten Ausführungsformen der Erfindung, wobei die Kraftsensorsysteme unterschiedliche Durchgangsöffnungen und/oder Nuten aufweisen;
• 8: eine perspektivische Ansicht eines Kraftsensorsystems gemäß einer alternativen bevorzugten Ausführungsform der Erfindung, mit einem gegenüber der 1 abweichend angeordneten Kraftmesssensor;
• 9: eine perspektivische Ansicht eines Kraftsensorsystems gemäß einer alternativen bevorzugten Ausführungsform der Erfindung, mit einem gegenüber den 1 und 8 abweichend angeordneten Kraftmesssensor;
• 10: eine perspektivische und eine Schnittansicht eines Kraftsensorsystems gemäß einer alternativen bevorzugten Ausführungsform der Erfindung, mit einem gegenüber 1 abweichend angeordneten Kraftmesssensor und mit einer abweichenden Kabelverbindung; und
• 11: eine Schnittansicht eines Kraftsensorsystems gemäß einer alternativen bevorzugten Ausführungsform der Erfindung, mit einem gegenüber 1 abweichend angeordneten Kraftmesssensor.

In the following, the invention is explained by way of example with reference to the attached drawings using preferred exemplary embodiments, the features shown below being able to represent an aspect of the invention both individually and in combination. Show it:

• 1 : a longitudinal section through a force sensor system according to a first preferred embodiment of the invention, with a housing arrangement, a force measuring sensor and an abutment body, a load acting on the housing arrangement in the area of the abutment body;
• 2 : a longitudinal section through a force sensor system according to an alternative preferred embodiment of the invention, the force sensor system opposite 1 has a further abutment body and is subjected to a different load which acts on the housing arrangement in the region of the abutment body;
• 3 : a perspective view of a longitudinal section of the force sensor system according to the first preferred embodiment of the invention;
• 4th : a perspective view of the entire force sensor system according to the first preferred embodiment of the invention;
• 5 : a symbolic detailed view of the longitudinal section of the force sensor system according to the first preferred embodiment of the invention in the area of the abutment body;
• 6th : a perspective view of the force sensor system according to the first preferred embodiment of the invention, mounted between two components;
• 7th : several views of force sensor systems according to different preferred embodiments of the invention, the force sensor systems having different through openings and / or grooves;
• 8th : a perspective view of a force sensor system according to an alternative preferred embodiment of the invention, with one opposite to FIG 1 differently arranged force measuring sensor;
• 9 : a perspective view of a force sensor system according to an alternative preferred embodiment of the invention, with one opposite to the 1 and 8th differently arranged force measuring sensor;
• 10 : a perspective and a sectional view of a force sensor system according to an alternative preferred embodiment of the invention, with one opposite 1 differently arranged force measuring sensor and with a different cable connection; and
• 11 : a sectional view of a force sensor system according to an alternative preferred embodiment of the invention, with an opposite 1 differently arranged force measuring sensor.

• eine Gehäuseanordnung 12 mit mindestens einer Durchgangsausnehmung 14, die mindestens einen Durchmesser D1 aufweist, um mindestens einen Kraftmesssensor 16 aufzunehmen;
• mindestens einen Kraftmesssensor 16, der in der mindestens einen Durchgangsausnehmung 14 angeordnet ist; und
• mindestens einen Widerlagerkörper 18, der in der mindestens einen Durchgangsausnehmung 14 angeordnet ist, wobei das Kraftsensorsystem 10 zwischen dem mindestens einen Widerlagerkörper 18 und der Durchgangsausnehmung 14 radiales Spiel RS aufweist.

the 1 until 11 show a variety of embodiments of a preferred force sensor system 10 . This includes all force sensor systems 10 according to the teachings of the invention:

• a housing assembly 12th with at least one through recess 14th that have at least one diameter D1 has to at least one force measuring sensor 16 record;
• at least one force measuring sensor 16 , in the at least one through recess 14th is arranged; and
• at least one abutment body 18th , in the at least one through recess 14th is arranged, wherein the force sensor system 10 between the at least one abutment body 18th and the through hole 14th radial play RS having.

The illustrated preferred embodiments of the force sensor system 10 are according to the 1 until 11 also characterized in that the at least one through recess 14th at least two different diameters D1 , D2 has, namely a small diameter D1 and a larger diameter D2 ;
the at least one force measuring sensor 16 in the at least one through recess 14th in the area of the small diameter D1 is arranged; and
the at least one abutment body 18th in the at least one through recess 14th in the area of the larger diameter D2 is arranged, wherein the force sensor system 10 between the at least one abutment body 18th and the through hole 14th in the area of the larger diameter D2 the radial play RS having. However, these are preferred but not limiting features of the force sensor system 10 .

The force measuring sensor 16 detects loads acting on it B. and forwards this information by means of a cable connection 40 the end

According to a preferred and not shown embodiment of the invention it is provided that one or more force measuring sensors 16 Strain gauges is or are, preferably glued or sputtered.

In contrast, shown in the disclosed figures, even if only preferred and not limiting, that one or more force measuring sensors 16 essentially a cylindrical shape with at least one end face 20th and a lateral surface 22nd has or have, wherein the at least one end face 20th and the outer surface 22nd Have meandering elongation means. The cylinder shape is clearly schematized in the figures. With a view to the cylindrical shape, this essentially means that the respective force measuring sensor 16 along the through recess 14th can be performed and at the same time sufficient contact to the passage recess 14th has to perform a qualitative force measurement.

It is provided according to the illustrated embodiment that the abutment body 18th Are rolling elements. Again, this is a separate feature and not limiting.

Especially in 5 the exemplary embodiment can be clearly seen that the at least one through recess 14th between the at least one force measuring sensor 16 and the at least one abutment body 18th a spacer device designed as a step or support shoulder 24 has to the abutment body 18th load-free to the force measuring sensor 16 to be countered. This is shown by way of example as a preferred embodiment, with the at least one through recess 14th in the transition area from the larger diameter D2 on the small diameter D1 a step or support shoulder as a spacer device 24 has to the abutment body 18th to be countered. This becomes the face 20th of the force measuring sensor 16 through the abutment body 18th not burdened.

Furthermore, the exemplary embodiment is shown in FIGS 1 until 11 shown in such a way that the at least one through recess 14th a cover element at one or both ends 26th has, which is preferably designed in two stages that an inner diameter segment 28 in the larger diameter D2 the through recess 14th engages and that an even larger diameter outer diameter segment 30th on an outside surface 32 the housing arrangement 12th rests. So the embodiment demonstrates 1 a cover element 26th on and the embodiment after 2 two cover elements 26th . This is advantageous, for example, when a respective abutment body 18th is designed as a rolling element, since rolling element steels tend to corrode. This provides increased protection against corrosion and other harmful influences, such as dust particles.

Furthermore, it is preferably provided that the housing arrangement 12th one or more through openings 34 and / or one or more grooves 36 having. In 6th is shown as an example that the force sensor system 10 via the through openings 34 with two components 38 connected is. Among other things 7th shows in the 7a , 7c and 7d different preferred configurations of grooves 36 in order to use this to set a flow of force for force detection. In 7b it is preferable to see that the force flow for force detection is via a passage opening 34 can be adjusted.

Exemplary in 2 is shown that the force sensor system 10 at least two abutment bodies 18th in a through recess 14th having,
which preferably extends along the through recess 14th are arranged opposite one another, and / or
which in particular the force measuring sensor 16 along the through recess 14th surrounded at one end each. The latter feature means that an abutment body 18th is arranged closer to the outside area than the force measuring sensor to be protected 16 .

In the figures it is shown by way of example that the housing arrangement 12th Is cuboid. This shape has proven to be particularly advantageous, with other shapes also being used for the housing arrangement 12th are possible, provided that they allow a power shunt.

List of reference symbols

10

Force sensor system

12th

Housing arrangement

14th

Through recess

16

Force measuring sensor

18th

Abutment body

20th

Face

22nd

Outer surface

24

Spacer

26th

Cover element

28

Inside diameter segment

30th

Outside diameter segment

32

Outer surface of the housing assembly

34

Through opening

36

Groove

38

Component

40

Cable connection

D1

small diameter

D2

larger diameter

RS

radial play

B.

load

Claims (10)

Force sensor system (10), having - A housing arrangement (12) with at least one through recess (14) which has at least one diameter (D1) in order to receive at least one force measuring sensor (16); - At least one force measuring sensor (16) which is arranged in the at least one through recess (14); and - At least one abutment body (18) which is arranged in the at least one through recess (14), the force sensor system (10) having radial play (RS) between the at least one abutment body (18) and the through recess (14). Force sensor system (10) Claim 1 , characterized in that - the at least one through recess (14) has at least two different diameters (D1, D2), namely a small diameter (D1) and a larger diameter (D2); - The at least one force measuring sensor (16) is arranged in the at least one through recess (14) in the area of the small diameter (D1); and - the at least one abutment body (18) is arranged in the at least one through recess (14) in the area of the larger diameter (D2), the force sensor system (10) between the at least one abutment body (18) and the through recess (14) in the area of the larger diameter (D2) has the radial play (RS). Force sensor system (10) according to at least one of the Claims 1 or 2 , characterized in that one or more force measuring sensors (16) is or are strain gauges, preferably glued or sputtered, and / or essentially has or have a cylindrical shape with at least one end face (20) and / or a lateral surface (22), wherein which have at least one end face (20) and / or the lateral surface (22) extending in a meandering manner. Force sensor system (10) according to at least one of the preceding claims, characterized in that one or more abutment bodies (18) are rolling bodies. Force sensor system (10) according to at least one of the preceding claims, characterized in that the at least one through recess (14) between at least one force measuring sensor (16) and at least one abutment body (18) has a spacing device (24) around the abutment body (18) without stress to counterbalance the force measuring sensor (16). Force sensor system (10) according to at least one of the preceding claims, characterized in that the at least one through recess (14) has a cover element (26) at one or both ends, which is preferably designed in two stages such that an inner diameter segment (28) is inserted into the at least one diameter (D2) of the through recess (14) engages and that an outer diameter segment (30) having a larger diameter rests on an outer surface (32) of the housing arrangement (12). Force sensor system (10) according to at least one of the preceding claims, characterized in that the housing arrangement (12) has one or more through openings (34) and / or one or more grooves (36) in order to be connected to a component (38) via this or these, and / or to provide a flow of force via this or these Adjust force detection. Force sensor system (10) according to at least one of the preceding claims, characterized in that the force sensor system (10) has at least two abutment bodies (18) in a through recess (14), which are preferably arranged opposite one another along the through recess (14). Housing arrangement (12) for a force sensor system (10) according to at least one of the preceding claims, characterized by the features of the housing arrangement (12) according to at least one of the preceding claims, wherein the housing arrangement (12) is preferably cuboid. Force measuring sensor (16) for a force sensor system (10) according to at least one of the preceding claims, characterized by the features of the force measuring sensor (16) according to at least one of the preceding claims.

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