Sensors that measure distance or position

Abstract

The object of the present invention is to provide reliable measurement operation in a wide variety of environmental conditions using structurally simple means. This object is achieved by designing and developing a sensor for measuring distance or position, in particular a sensor that operates capacitively or inductively or based on eddy currents, comprising a support (10; 20) with a planar area (2) and sensor elements (5a, 5b) arranged on or integrated into the planar area (2), so that the support (10; 20), the planar area (2) or the sensor elements (5a, 5b) can be used in conjunction with a device (3) for guiding a gaseous medium along the planar area (2) or the sensor elements (5a, 5b).

Description

[Technical Field]

[0001] The present invention relates to a distance or position measuring sensor, in particular a sensor that operates capacitively, inductively or based on eddy currents, comprising a support with a planar area and a sensor element that is arranged on or integrated into this planar area. [Background technology]

[0002] For example, measuring roll gap can be very effective using a high resolution capacitive sensor. For this purpose, flat sensors are used which are capable of measuring on one or both sides and are, for example, capable of measuring gaps of more than 0.5 mm between two rolls. The measurement object is not limited to a roll, and may be used for both flat and curved surfaces.

[0003] Depending on the location of use, if the sensor is installed horizontally, particles and dust may easily remain on the sensor surface, resulting in a large amount of particle accumulation during measurement.

[0004] Too many particles on the sensor can interfere with distance measurements. Capacitive sensors respond not only to the actual distance they measure, but also to the medium within the gap. That is, the presence of a non-conductive medium in the gap increases the capacitance, which, in the evaluation of the sensor signal, has the same effect as a decrease in distance. Therefore, it is not possible to distinguish between an increase in particle accumulation and a gradual change in distance.

[0005] However, conductive dust such as graphite or carbon fiber can change the dielectric constant and can also cause short circuits or even complete failure of capacitive gap measurements.

[0006] According to the prior art, gap sensors may have a separate air outlet nozzle mounted adjacent to the sensor, which creates turbulence in the sensor area. The turbulence thus generated, accompanied by air vortices, can cause thin and / or flexible sensors to bend and vibrate, thereby making measurements impossible.

[0007] Where possible, various protective plates and other mechanical measures may be used in dusty environments. These measures provide mechanical protection against contamination or at least help to reduce contamination, but increase the installation space required.

[0008] If installation conditions permit, optical sensors integrated into protective housings are also used in such applications. These protective housings may then have pneumatic connectors, for example to keep open the optical windows of the sensor elements. However, these protective housings have very limited installation possibilities due to their size. Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention to provide a sensor of the type mentioned at the outset which allows a reliable measurement response by means of simple design under a wide variety of ambient conditions. [Means for solving the problem]

[0010] The above-mentioned object of the invention is achieved by a sensor having the features of claim 1. The sensor is therefore constructed and developed in such a way that a device for generating a flow of gaseous medium along the planar area or sensor element is assigned to the support, the planar area or the sensor element.

[0011] In accordance with the present invention, it has now been discovered that the above-mentioned objectives may be surprisingly easily achieved by preferably producing an apparatus for removing or reducing dirt and particle buildup on a planar area or sensor element. Furthermore, according to the invention, the device may be assigned to the support, the planar area or the sensor element in such a way that a flow of gaseous medium is formed along the planar area or the sensor element. Such a flow along the planar area or sensor element then ensures, on the one hand, that dirt and particles accumulating on the planar area or sensor element are effectively removed or reduced, and, on the other hand, that mechanical distortion of the sensor element due to bending of the sensor element by turbulent air vortices is minimized. Thus, dirt and particles can be very gently removed from the planar area or sensor element using a gaseous medium. In this case, adverse effects on the measurement response are largely avoided and the sensor provides reliable measurement results even in dirty and particulate environments.

[0012] The sensor according to the invention therefore provides a sensor that allows a reliable measurement response under a wide variety of ambient conditions by means of simple design.

[0013] For the purpose of particularly gentle removal of dirt and particles on the planar area or sensor element, the device may be configured to generate a laminar flow of the medium along the planar area or sensor element. Such laminar flow is characterized by a constant flow rate and does not impose sudden shocks on the sensor element or flat area, as may occur, for example, with turbulent air vortices. Additionally, laminar flow inherently prevents dirt and particles from adhering to the planar area or sensor element. Dirt and particles include, among other things, dust and liquids such as water and oil. In any case, it is advantageous for the flow to be stable so as not to induce lateral forces or bending moments on the planar area or sensor element. Lateral forces and bending moments can lead to vibrations of the thin support and sensor element. Additionally, laminar flow allows for better control of dirt and particle trajectories.

[0014] For particularly effective removal of particles and other contaminants, the device may have an adjustment or regulation mechanism for adjusting or regulating the flow and / or rate of the medium. In this case, the constant flow rate may be adjusted and / or regulated by using appropriate measurement sensors. Furthermore, if contamination is already present, the conditioning device may generate a pressure surge or pulsating flow to remove contamination caused, for example, by a stopped supply of medium or compressed air. Such contamination can result in deposits that may remain more or less strongly attached to the planar area or sensor element depending on the material, either when contamination occurs suddenly in large quantities or during long periods of cessation. In this case, the flow may be generated initially at a relatively high pressure or a relatively high Reynolds number, and then the pressure may be reduced to the desired flow or rate.

[0015] In certain embodiments, the flow of the medium may be directed in a direction perpendicular to the measurement direction. This allows dirt and particles to be intentionally excluded from the measurement line predetermined by the measurement direction. Furthermore, the flow of the medium may be guided parallel to the planar area or the sensor element. This ensures that dirt and particles can be removed from the planar area or sensor element without any bending moments acting on the planar area or sensor element that would impede or even make measurement impossible.

[0016] For reliable operation of the sensor, the device may include guiding elements for the flow of the medium. The guide element is assigned to the support, the surface area or the sensor element and / or can be connected to the support, the surface area or the sensor element and can be separated from the support, the surface area or the sensor element. Such a guide element makes it possible to guide the flow of the gaseous medium particularly reliably. To remove dirt or particles on the planar area or sensor element, the media may be conveyed by the guide elements in various desired directions depending on the configuration of the guide elements. Being capable of being docked and detached, the sensor may operate without such guide elements if desired. This allows for great flexibility, since the sensor can be used on the one hand with guide elements and on the other hand without guide elements. This also makes it possible to retrofit the sensor with a guide element.

[0017] In order to achieve a particularly reliable flow generation and thus a reliable operation of the sensor, the guide element may comprise a connector for a supply tube of the medium. In this case, the medium is guided directly and reliably in a controllable manner via or by the guide element to the surface area or sensor element.

[0018] Furthermore, in order to ensure particularly controlled flow generation, the guide element may comprise a medium receiving or dispensing chamber which is in fluid communication with the connector. Such a receiving or distributing chamber may act as a buffer chamber for the medium and transport the received medium in a controlled manner to the planar area or sensor element.

[0019] To ensure a flow directed towards the planar area or the sensor element, the receiving or distribution chamber may comprise at least one outlet for the medium. When one outlet is formed, all of the medium received in the receiving chamber or the dispensing chamber may be intentionally transported along the flat area or the sensor element. If two or more outlets are formed, the medium may be supplied to multiple planar areas or sensor elements of the sensor so that the medium received in the receiving chamber or distribution chamber can flow along multiple planar areas or sensor elements. In the case of a gap sensor with two sensor elements measuring in opposite directions, the medium may be conveyed simultaneously along both sensor elements or along the two associated planar areas to remove dirt or particles. The parallel flows thus generated mean that the sensor element is sandwiched between the two flows, which particularly reliably avoids the occurrence of bending moments on the sensor element that would adversely affect the measurement.

[0020] Depending on the requirements and the configuration of the planar area or sensor element, the at least one outlet may comprise a slit, a slit with at least one guiding strip, or a plurality of openings arranged adjacent to each other. If a slit is formed (with or without guide strips), a wide, thin, flat stream may be produced. A plurality of openings positioned adjacent to each other may also ensure a flat flow.

[0021] The guide element may be made in one piece or in multiple pieces. If made of multiple parts, the guide elements may be individually adapted to various measurement conditions, for example with respect to geometrical properties. Furthermore, since the device is made up of multiple components, damaged components can be easily replaced and undamaged components can continue to be used.

[0022] In a further embodiment, the guide element may comprise or consist of two connectable or screwable half shells. Such half shells may then be very simply attached to a support or a sensor from different sides.

[0023] In this case, the support may be firmly arranged in the region between at least two half shells and / or the half shells may be fixed to the support by a clamping action, which results in an arrangement of the support that is well protected by the half shells and a reliable and stable connection between the support and the half shells or guide elements.

[0024] Depending on the desired flow direction, the support and / or the guide elements and / or the receiving or distribution chambers may have a curved or angled shape. For example, the curved or angled shape may have a curvature or angle of about 90° to deflect the flow from the feed direction by about 90°.

[0025] In one particular embodiment, the support or the planar area may comprise two sensor elements measuring in opposite directions, thereby forming a gap sensor that makes it particularly easy to measure the gap width. More generally, the support or planar area may include multiple sensor elements measuring different directions, where the number and directions of the sensor elements may be three or more depending on the application.

[0026] For a particularly simple and reliable design, the carrier can be configured as or include a printed circuit board. The use of a printed circuit board as a support has proven useful in practice, allowing the sensor to be manufactured flexibly and economically.

[0027] To ensure reliable transmission of drive and / or measurement data to the evaluation electronics, the sensor element may be connected to the evaluation electronics via a coaxial or triaxial cable. By using a triaxial cable, a high shielding effect can be obtained.

[0028] Further advantages and aspects of embodiments of sensors according to the present invention are described below.

[0029] Permanently mounted or retrofittable guide elements for the medium allow for the introduction of a flow or air current perpendicular to the measuring direction, which can then blow away dirt and particles. The two half shells may be configured to create an air flow parallel to the sensor surface or sensor element.

[0030] Flow may be generated across the entire sensor surface or across a sensor element, across multiple sensor elements, and optionally on both sides of a support.

[0031] By providing lateral connecting channels in the guide element, it is possible to form an air chamber or a receiving or distribution chamber which is supplied with air from one point (one connector) but which has air exiting from several openings or outlets. The direction of air or medium supply is not critical and may be adjusted individually depending on the installation situation. For example, compressed air may be supplied through the connector.

[0032] The air guide, or the guide element, may be manufactured as desired from a simple 3D printed plastic part to a more complex machined metal part. The guide or guide element and the air chamber or the receiving or distribution chamber may be formed as one unit.

[0033] In any case, the air outlets or blowouts can be manufactured in a simple configuration at the required positions, respectively. In a simple example, the air outlet or nozzle may comprise a slit nozzle with or without strips in the gap to guide the air (preferably in a laminar flow).

[0034] Providing air outlets or blow-out ports on both sides of the gap sensor has the advantage that temperature changes on only one side due to air or medium flow will not occur, and thin / flexible sensors will not bend in one direction. This is because air or medium is conveyed to both sides from a common air chamber or receiving or distribution chamber. Often the sensor is intentionally cooled by a temperature difference between the air or medium and the sensor, but this effect is similar on both sides and the centrally located sensor remains upright.

[0035] The sensor's elongated configuration, combined with a single connector or pneumatic connector, allows for a very compact sensor that can be easily adapted to tight installation conditions. In this case, the guide element may be screwed onto the sensor, which makes it possible to maintain the sensor in a predetermined screwed position.

[0036] The guide elements may be adapted to the shape of the roll and may further increase the mechanical stability of thin sensors, for example with a thickness of 0.4 mm. This also makes it possible to reduce vibration of the sensor due to external vibration, for example. The guide element may have a curved shape.

[0037] Sensor embodiments according to the present invention may be used not only for roll gap measurement, but also for gap measurement in harsh environments where contamination may occur in general.

[0038] Typically, for example, a sensor for roll gap measurement may be manufactured as a planar sensor having a device for generating a flow of gaseous medium along the planar area or sensor element of the sensor. The device for generating a flow of gaseous medium is also called a blowing device, i.e. a device for blowing away dirt and particles from the planar area or the sensor element.

[0039] There are various possibilities for advantageously configuring and developing the invention. In this respect, reference is made on the one hand to the dependent claims and on the other hand to the following description of embodiments of the sensor according to the invention. The construction and development of the present invention will now be explained in conjunction with the description of preferred exemplary embodiments with reference to the drawings. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a perspective view showing a sensor according to a first embodiment of the present invention; [Figure 2] 2 is a side view, partly in section, of the first embodiment of FIG. 1 in use between two rolls; FIG. [Figure 3] 2 shows two exploded views of the first embodiment of FIG. 1, one seen from above and the other seen from diagonally below. [Figure 4] 2A and 2B are a side view and a plan view showing a partial cross section of the first embodiment of FIG. 1; [Figure 5] FIG. 6 is an exploded view of a sensor according to a second embodiment of the present invention, viewed obliquely from above. [Figure 6] 6A and 6B are a side view and a plan view showing the second embodiment of FIG. 5; DETAILED DESCRIPTION OF THE INVENTION

[0041] In the following embodiments of the sensor according to the invention configured as a gap sensor 1, the same reference numbers denote the same components.

[0042] FIG. 1 shows a perspective view of a first embodiment of a sensor according to the invention. The sensor is configured as a gap sensor 1 comprising a substrate or support having a planar area 2 and a device 3 for generating a flow of gaseous medium along the planar area 2 . Here, the device 3 is also called a blowing device 3. The blowing device 3 includes a connector 4 for a gaseous medium (in this case air). Instead of air, other gaseous media may be used to generate the flow. In this embodiment, the connector 4 is configured as a compressed air connector 4, to which a pressure hose (not shown) can be connected. At the front end of the planar area 2, sensor elements 5a, 5b are arranged on either side of the planar area 2, which perform measurements in opposite directions to determine the gap width. Compressed air can be forced through the connector 4 into the gap sensor 1, causing the air flow to remove dirt and particles from the planar area 2 or the sensor elements 5a, 5b.

[0043] Furthermore, the gap sensor 1 includes two electrical connectors for the two capacitive sensor elements 5a, 5b, which take the form of triaxial cables 6a, 6b that meet at connector areas 7 on the gap sensor 1.

[0044] FIG. 2 shows the gap sensor 1 of FIG. 1 in a partial cross-sectional view in an arrangement for measuring the roll gap 8 between two rolls 9a, 9b. In this case, the gap sensor 1 is arranged to the side of the rolls 9a, 9b, ie in an area through which the material to be rolled (not shown) does not pass. The planar area 2 projects into the nip 8 together with the sensor elements 5a, 5b. Alternatively, the gap sensor 1 may be located in the area of ​​the journal of the roll (not shown).

[0045] The compressed air connector 4 and the triaxial cable 6 are located behind the gap sensor 1 to prevent the pressure hose (not shown) from coming into contact with the rolls 9a, 9b.

[0046] The roll gap 8 is measured using sensor elements 5a, 5b, with a first sensor element 5a making a measurement on the upper roll 9a and a second sensor element 5b making a measurement on the lower roll 9b.

[0047] FIG. 3 shows two exploded views of the gap sensor 1 of FIG. 1, one seen from above (A) and the other seen from diagonally below (B). The gap sensor 1 comprises two sensor elements 5 a , 5 b arranged on a planar area 2 of a planar support or substrate 10 . In the connector area 7, the sensor elements 5a, 5b are in contact with the triaxial cables 6a, 6b. The blowing device 3 comprises two half shells 11a, 11b, which together form a guide element for the gaseous medium (in this case air). The upper half-shell 11a houses a compressed air connector 4 for a compressed air hose (not shown) which delivers compressed air along the support or substrate 10 from above in the direction of the upper first sensor element 5a. The lower half-shell 11b supports supports or substrates 10 and directs compressed air along these supports or substrates 10 from below in the direction of the lower second sensor element 5b. Furthermore, this lower half-shell 11b also includes strips 12 that provide additional support for the substrate 10. The strip 12 is then placed in an air inlet nozzle 13 which serves as the inlet of the upper half shell 11a, and prevents the substrate 10 from vibrating due to the impact of compressed air. The two half shells 11a, 11b of the blowing device 3 are connected to each other by screws 14a, 14b and fixed to a support or substrate 10 by a clamping action.

[0048] These two half shells 11a, 11b form a cavity 15 which is in fluid communication with the air inlet nozzle 13 and has a side opening towards the sensor elements 5a, 5b, thereby forming air outlet nozzles 16a, 16b, respectively, which function as air outlets. The air inlet nozzle 13 forms the entrance to a cavity 15 which functions as an air receiving or distribution chamber. Via the air outlet nozzles 16a, 16b, compressed air is guided along the substrate 10 in the direction of the sensor elements 5a, 5b, thereby effectively removing the dirt. In the connector area 7, the substrate 10 includes two threaded bushings 17a, 17b, which can be used to fasten the gap sensor 1 to an object (not shown). Alternatively, this fixing may be effected via the blow-off device 3, for example by forming threaded lugs or threaded bushes on the blow-off device 3.

[0049] FIG. 4 shows a partially cross-sectional side view (A) and a plan view (B) of the gap sensor 1 according to the first embodiment of FIG. Through an air passage 18 (preferably connectable and separable) in the compressed air connector 4, compressed air is guided through the air inlet nozzle 13 into the cavity 15 and then delivered to the air outlet nozzles 16a, 16b.

[0050] FIG. 5 shows an exploded view, seen obliquely from above, of a gap sensor 1 equipped with an angled embodiment of a blowing device 19, which is a second embodiment of a sensor according to the invention. The support or substrate 20 is angled, ideally at a 90° angle. The gap sensor 1 can therefore be positioned so that the sensor elements 5a, 5b protrude into the roll gap 8 (not shown here) and the connectors (triaxial electrical cables 6a, 6b, compressed air connector 4) are routed laterally. This avoids interference with the rolling process. In this embodiment, the half shells 21a, 21b are configured so that the cavity 22 is similarly angled and the air outlet nozzles 23a, 23b again direct the compressed air towards the sensor elements 5a, 5b. The half shells 21a, 21b are connected to each other by screws 14a, 14b. Furthermore, the substrate 20 is also connected to the lower half shell 21b by press-fit sockets 24a, 24b, and is mechanically fixed. In this embodiment, the lower half shell 21b is also configured to fix the gap sensor 1 thereto. For this purpose, the lower half-shell 21b is formed with a metal bracket 25 for laterally fixing the gap sensor 1, for example to a roll stand (not shown).

[0051] FIG. 6 shows a side view (A) and a plan view (B) of the gap sensor 1 according to the second embodiment of FIG. The metal bracket 25 has an opening or hole 26 for fastening to an object (not shown here).

[0052] For further advantageous configurations of the gap sensor 1 according to the invention, reference is made to the general part of the description and the appended claims in order to avoid repetition.

[0053] Finally, the above-described embodiments are merely intended to discuss the claimed teachings and are not intended to limit the teachings to the embodiments. [Explanation of symbols]

[0054] 1. Gap sensor 2...plane area 3. Device, blowing device 4 Connector, compressed air connector 5a, 5b...sensor element 6, 6a, 6b... Triaxial cable 7 Connector area 8 Roll gap 9a, 9b... Roll 10 Support, substrate 11a, 11b... Half shell 12 strips 13 Air inlet nozzle 14a, 14b...Screws 15...Cavity part 16a, 16b Air outlet nozzle 17a, 17b...Threaded bushing 18 Air flow path 19...device, blowing device 20 Support, substrate 21a, 21b... Half shell 22...Cavity part 23a, 23b Air outlet nozzle 24a, 24b... Press-fit socket 25 Metal bracket 26 Opening

Claims

1. A distance or position measuring sensor, which operates capacitively or inductively or based on eddy currents, comprising a support (10; 20) having a planar area (2) and sensor elements (5a, 5b) arranged on or integrated into said planar area (2), 1. A sensor characterized in that a device (3) for generating a flow of a gaseous medium along the planar area (2) or along the sensor element (5a, 5b) is assigned to the support (10; 20), the planar area (2) or the sensor element (5a, 5b).

2. 2. The sensor according to claim 1, characterized in that the device (3) is configured to generate a laminar flow of the gaseous medium along the planar area (2) or along the sensor element (5a, 5b).

3. 3. A sensor according to claim 1 or claim 2, characterized in that the device (3) comprises an adjustment or regulation mechanism for adjusting or regulating the flow and / or volumetric flow of the gaseous medium.

4. 4. The sensor according to claim 1, wherein the flow of the gaseous medium is guided in a direction perpendicular to the measuring direction and / or parallel to the planar area (2) or the sensor elements (5a, 5b).

5. the device (3) comprises a guide element for the flow of the gaseous medium, 5. The sensor according to claim 1, wherein the guide element is assigned to the support (10; 20), the planar area (2) or the sensor element (5a, 5b) and / or can be connected to the support (10; 20), the planar area (2) or the sensor element (5a, 5b) and can be separated from the support (10; 20), the planar area (2) or the sensor element (5a, 5b).

6. 6. A sensor according to claim 5, characterized in that the guide element comprises a connector (4) for a supply pipe of the gaseous medium.

7. 7. A sensor according to claim 5 or 6, characterized in that the guide element comprises a receiving or dispensing chamber (15; 22) for the gaseous medium, which is in fluid communication with the connector (4).

8. 8. A sensor according to claim 7, characterized in that the receiving or distribution chamber (15; 22) comprises at least one outlet (16a, 16b; 23a, 23b) for the gaseous medium.

9. 9. The sensor according to claim 8, characterized in that the at least one outlet (16a, 16b; 23a, 23b) comprises a slit, a slit with at least one guide strip (12), or a plurality of openings arranged adjacent to each other.

10. 10. A sensor according to any one of claims 5 to 9, characterized in that the guide element is made of several parts.

11. 11. The sensor according to claim 5, wherein the guide element comprises or is made up of two connectable or screwable half shells (11a, 11b; 21a, 21b).

12. 12. The sensor according to claim 11, characterized in that the support (10; 20) is arranged in the region between at least the two half shells (11a, 11b; 21a, 21b) and / or the two half shells (11a, 11b; 21a, 21b) are fixed to the support (10; 20) by a clamping action.

13. 13. A sensor according to any one of the preceding claims, characterized in that the support (20) and / or the guide element and / or the receiving or dispensing chamber (22) have a curved or angled shape.

14. 14. A sensor according to any one of claims 1 to 13, characterized in that the support (10; 20) or the planar area (2) contains two sensor elements (5a, 5b) measuring in opposite directions, thereby forming a gap sensor (1).

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