Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D11/00—Component parts of measuring arrangements not specially adapted for a specific variable
  • G01D11/30—Supports specially adapted for an instrument; Supports specially adapted for a set of instruments
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
  • G01B5/0011—Arrangements for eliminating or compensation of measuring errors due to temperature or weight
  • G01B5/0014—Arrangements for eliminating or compensation of measuring errors due to temperature or weight due to temperature
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
  • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
  • G01B7/023—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring distance between sensor and object
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
  • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure

Definitions

• the invention relates to a sensor for distance and/or position measurement with an essentially cylindrical housing and a sensor element that works according to the inductive, the capacitive or the eddy current principle and is at least partially arranged in the housing.
• the invention relates to a system with such a sensor and a fastening device.
• Sensors for distance measurement are used at different temperatures and distances. If you want to measure a distance very precisely, it is important to know the thermal expansion of the sensor due to temperature changes or to define it as precisely as possible in order to be able to compensate for it as well as possible.
• Cylindrical sensors without a thread are usually clamped in a clamping device. With this type of clamping, the exact location of the frictional connection between the clamping device and the sensor housing is not known. In the case of peripheral clamping in particular, it is unclear where the sensor is actually “clamped". Due to minor tolerances in the sensor housing or the clamping device, or due to small impurities (dust or grease/oil) in the clamp, the location of the frictional connection cannot be determined precisely, or it can even change over time or under changing temperatures.
• the sensor expands with the typical material-specific expansion coefficient of the housing, starting from the terminal point.
• the clamping device also expands due to its own material-specific coefficient of expansion. This causes the sensing element (electrode/coil) of the sensor to move towards or away from the target due to expansion, depending on the Materials of the sensor and the clamping device.
• a measurement error is the result, since the distance to the measurement object changes due to the clamping.
• the present invention is therefore based on the object of designing and developing a sensor and a system with a sensor and a fastening device in such a way that reliable measurement at different temperatures is made possible with structurally simple means.
• the above object in relation to the sensor is achieved by the features of claim 1.
• the sensor in question for measuring distance and/or position has an essentially cylindrical housing and a sensor element that works according to the inductive, capacitive or eddy current principle and is at least partially arranged in the housing, characterized in that on at least one fastening area is formed on the surface of the housing, which extends in the circumferential direction around the housing and is designed as an elevation or as a depression, wherein the housing can only be non-positively connected to the fastening area with a fastening device.
• improved clamping of the at least essentially cylindrical sensor can be achieved by the location of the clamping being reproducibly determined by the defined fastening area, preferably the sensor is only in contact with the fastening device with its fastening area.
• the location of the frictional connection can be precisely defined by the fastening area.
• the extent of a known point or a very small area can be calculated in the later measurement application, or the measurement can then be repeated extremely precisely over the entire application temperature range and can be actively compensated in the measurement system.
• cylindrical is to be understood in the broadest sense. It does not necessarily have to be a circular cylinder, it can also have other shapes, for example a square or oval base, be crooked and/or the base can change over the height of the cylinder.
• the elevation can have a maximum height of 0.05 mm and/or the depression can have a maximum depth of 0.05 mm.
• the fastening area can be realized in a structurally simple manner become.
• the housing can be made of steel, for example stainless steel, or of a steel alloy.
• the fastening area can be delimited by material depressions from the surface of the housing lying outside of the fastening area.
• This constructive measure enables a particularly simple positioning of the sensor in relation to the fastening device.
• the material depressions are V-shaped or U-shaped or semi-circular or trapezoidal. Appropriate geometries can be produced, for example, by turning.
• the fastening area can be formed by a large number of punctiform elevations. Due to the punctiform elevations, an improved frictional connection or improved clamping between the sensor and the fastening device can be generated. It is possible here for the punctiform elevations to be formed in one piece with the housing, i.e. to be machined out of the housing. Alternatively, the elevations can be applied to the housing.
• the fastening area can extend in a ring shape around the housing.
• Such an encircling ring can be worked out in a particularly simple manner during manufacture of the housing, for example when the housing is rotated.
• the width of the ring-shaped fastening area can be selected to be as small as possible and at the same time matched to the size of the housing in such a way that the fastening area is wide enough to prevent the housing from tilting when it is connected to the fastening device.
• the width of the ring-shaped fastening area should be as small as possible in order to define the location of the frictional connection or the clamping as precisely as possible.
• a ring-shaped attachment area that is too narrow increases the risk the tilting of the sensor in the fastening device.
• the decisive factor is the ratio of the width of the ring-shaped fastening area to the length of the housing, or the length of the fastening device.
• the fastening area can advantageously have a width in the range from 0.5 mm to 2.5 mm, in particular from 1 mm to 2 mm.
• a distance between a measuring surface of the sensor and the fastening area can be formed in such a way that the different temperature expansions of the housing and the fastening device are at least compensated. In other words, this distance can be selected in such a way that an optimal compensation of the different thermal expansion coefficients of the sensor housing and the fastening device is achieved.
• the distance between the measuring surface of the sensor (sensor front side) and the fastening area, viewed in the direction of extension of the sensor, could be 0.5 mm to 1.5 mm, preferably 2 mm.
• the fastening area can extend in a ring shape around the housing and the outer diameter of the housing in the fastening area can be larger than the outer diameter of the housing outside of the fastening area.
• the outer diameter of the housing in the fastening area is at most 0.05 mm, in particular at most 0.02 mm, preferably 0.01 mm, larger than the outer diameter of the housing outside of the fastening area.
• the ratio of the outer diameters of the fastening area and the rest of the housing to one another should be chosen appropriately.
• a larger outer diameter of the fastening area will be sufficient, for example 0.05 mm with a housing diameter of 10 mm, with smaller sensors the outer diameter of the fastening area should be chosen smaller, for example 0.01 mm with an outer diameter of the housing of 5 mm.
• the fastening device is advantageously designed in such a way that the sensor can be connected to the fastening device with a peripheral clamp.
• the sensor can be arranged in the opening in such a way that a fastening means, for example a fastening screw or a fastening pin, acts on the fastening area of the housing.
• FIG. 1a shows a schematic representation of a side view of a sensor according to the invention
• FIG. 1c shows an enlarged detail from FIG. 1a in a schematic representation
• FIG. 3 in a schematic representation a further partially sectioned view of the system according to FIG. 2, Fig. 4 in a schematic representation, a partially sectioned
• FIG. 5 in a schematic representation another partially sectioned
• FIG. 6 shows a sectional view of a system in a schematic representation
• FIG. 7 shows a schematic representation of a sectional view of a further exemplary embodiment of a system according to the invention.
• FIGS. 1a to 1c show a sensor 1, for example a capacitive displacement sensor, which can have a measuring range of 0.2 mm, for example.
• An annular fastening area 3 is formed on the housing 2, it also being possible for the fastening area 3 to have a different geometry.
• the ring-shaped fastening area 3 can be located, for example, approx. 3 mm to 5 mm behind the measuring surface 4 of the sensor element 5 (FIG. 1b).
• the housing 2 of the sensor 1 can have an outside diameter of 6 mm and a length of 12 mm, for example.
• the ring-shaped fastening area 3 can have an outer diameter 6, for example, which is 0.01 mm larger than the remaining outer diameter of the (cylindrical) housing 2 of the sensor 1.
• the width of the ring-shaped fastening area 3 can be 2 mm, for example be.
• the ring-shaped fastening area 3 is delimited from the rest of the housing 2 by material depressions 7, which are designed as V-shaped recesses (shown enlarged in FIG. 1c).
• the sensor 1 also has an annular fastening area 3 on the housing 2.
• FIG. Furthermore, it can be seen that the sensor 1 is introduced into an opening 8 of the fastening device 9 . Since the outer diameter 6 of the ring-shaped fastening area 3 is slightly larger than the outer diameter of the rest of the housing 2 , the sensor 1 is clamped to the fastening device 9 exclusively via the fastening area 3 .
• the fastening means 10 designed as a screw is tightened.
• the exemplary embodiment according to FIGS. 4 and 5 corresponds to the exemplary embodiment according to FIGS. 2 and 3, with the difference that the location of the clamping is determined by the ring-shaped fastening area 3 and the position of the fastening means 10 designed as a screw. It can be seen that the screw 10 rests exactly on the defined fastening area 3 and thus causes clamping at an extremely precisely defined position.
• FIG. 6 shows a system in which the sensor 1 has no fastening area. If the sensor 1 is clamped in a flattening 11 with a fastening device 9, the measuring surface 4 has a certain basic distance D, defined depending on the measuring task, from the bearing surface 12 for the measuring object (not shown). This basic distance D changes when the temperature changes due to the different temperature-dependent expansion coefficients of the materials used.
• the sensor 1 is made of stainless steel (V4A) and the fastening device 9 is made of aluminum, this expands more than the housing 2 of the sensor 1 when the temperature rises, as a result of which the basic distance D increases. If the sensor 1 does not have a defined fastening area 3, then the location of the frictional connection in the axial direction along the clamping area 13 is undefined. In extreme cases, the frictional connection could be right at the beginning (in the direction of the measuring surface 4) or at the end (in the direction of the cable outlet/connector). In Figures 6 and 7, these two extreme cases are referred to as variant a) and b): In case a), the location of the frictional connection is closer to the plug-side end 14 of the sensor 1.
• the relative expansion of the fastening device 9, symbolized by the arrow 15, acts over the entire length 15.
• the expansion of the sensor 1 acts in the opposite direction, symbolized by the arrow 16. Due to the different expansion coefficients, the resulting change in the basic distance D is very large.
• the location of the frictional connection is on the front measuring surface 4 of the sensor 1.
• the relative expansion of the fastening device, symbolized by the arrow 17, acts over the entire length 17.
• the expansion of the sensor 1 acts in the opposite direction, symbolized by the arrow 18. Due to the different expansion coefficients, the resulting change in the basic distance D is small.
• the relative extension can vary in size, as a result of which the basic distance D changes in a non-reproducible manner, with correspondingly disadvantageous effects on the measurement result.
• Figure 7 shows that the location of the adhesion can be better reproduced even with changing temperatures if you use the
• Fastening area 3 determines the location of the frictional connection to a local, here to a clamping area 13 that is narrowly limited in the axial direction.
• the location can be placed closer to the measuring surface 4, for example, or in the opposite direction closer to the cable outlet/connector.
• fastening device 0 fastening means 1 holder 2 contact surface 3 clamping area 4 plug-side end 5 expansion (fastening device) 6 expansion (sensor) 7 expansion (fastening device) 8 expansion (sensor)

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Clamps And Clips (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Family Cites Families (10)

• 2021
  • 2021-07-27 DE DE102021208078.2A patent/DE102021208078A1/de active Pending
• 2022
  • 2022-07-26 EP EP22753999.6A patent/EP4179279A1/de active Pending
  • 2022-07-26 CN CN202280051176.2A patent/CN117677821A/zh active Pending
  • 2022-07-26 WO PCT/DE2022/200171 patent/WO2023006163A1/de active Application Filing

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