Sensor for distance or position measurement

Abstract

The invention relates to a sensor for distance or position measurement, in particular a capacitive or inductive or eddy-current-based sensor, comprising a carrier (10; 20) and a sensor element (5a, 5b), which is arranged on or integrated in a planar region (2), the sensor being designed and further improved in order to achieve reliable measurement performance under different environmental conditions by means of a structurally simple manner in such a way that the sensor element (5a, 5b) is given to the carrier (10; 20), to which a device (3) for flowing a gaseous medium along the planar region (2) or the sensor element (5a, 5b) is assigned.

Description

Technical Field

[0001] The present invention relates to a sensor for distance or position measurement, in particular a capacitive or inductive or eddy current-based sensor, which has a carrier and a sensor element, the carrier having a planar area, and the sensor element being arranged on or integrated in the planar area. Background Art

[0002] To measure, for example, a roll gap, a high-resolution capacitive sensor can be used. For this purpose, flat, single-sided or double-sided measuring sensors are used, which can measure, for example, the gap between two rolls starting from 0.5 mm. Here, the measurement is not limited to rolls, but can be used for flat and curved surfaces.

[0003] Depending on the location of use, these measurements may be strongly contaminated by particles, especially when the sensor is mounted horizontally, and particles or dust can easily remain on the sensor surface.

[0004] Excessive particles on the sensor will adversely affect the distance measurement. A capacitive sensor responds not only to the actual distance to be measured, but also to the medium in the gap. This means that a non-conductive medium in the gap increases the capacitance, which is equivalent to a decrease in distance when evaluating the sensor signal. Therefore, it is impossible to distinguish the gradual deposition of particles from a slow change in distance.

[0005] Especially in the case of conductive dust, such as graphite or carbon fiber, in addition to causing a change in the dielectric constant, it may also cause a short circuit and render the capacitive gap measurement completely ineffective.

[0006] According to the prior art, in some individual cases in a gap sensor, a separate air discharge nozzle is installed near the sensor, but this will generate turbulence in the sensor area. The resulting turbulence with corresponding air vortices may cause a thin and / or flexible sensor to bend, or may also cause the sensor to vibrate. This will render the measurement result unusable.

[0007] If possible, in a dusty environment, various protective plates or similar mechanical protection devices can also be installed, which can provide mechanical protection against contamination or at least reduce contamination. However, this also places higher requirements on the required installation space.

[0008] As long as the corresponding installation situation permits, optical sensors installed in a protective housing can also be used for such applications. The protective housing also partially has an air interface, for example, to leave an observation window for the sensor element. However, due to its corresponding size, the protective housing will significantly limit the installation possibilities. Summary of the Invention

[0009] Accordingly, the object of the present invention is to provide a sensor of the type described at the beginning, which achieves reliable measurement performance under different environmental conditions in a structurally simple manner.

[0010] According to the present invention, the aforementioned object is achieved by a sensor having the features of claim 1. The sensor is designed and further improved such that means for causing a gaseous medium to flow along a planar region or a sensor element are assigned to a carrier, a planar region, or a sensor element.

[0011] According to the present invention, it has first been recognized that the aforementioned object can be solved in a surprisingly simple manner by cleverly implementing means for removing or reducing dirt or particles deposited on a planar region or a sensor element. It has further been recognized according to the present invention that the means are specifically assigned to a carrier, a planar region, or a sensor element such that a flow of the gaseous medium along the planar region or the sensor element is provided. This flow along the planar region or the sensor element ensures on the one hand an efficient removal or reduction of dirt or particles deposited on the planar region or the sensor element and on the other hand a minimal mechanical load on the sensor element due to air vortices caused by turbulence that lead to bending of the sensor element. The planar region or the sensor element can thus be very effectively cleaned of dirt or particles by means of the gaseous medium. In this way, it is possible to avoid to the greatest extent possible an adverse effect on the measurement performance of the sensor due to bending of the sensor element, and the sensor also provides reliable measurement results in an environment with dirt and particle accumulation.

[0012] Accordingly, the sensor according to the present invention provides a sensor that achieves reliable measurement performance under different environmental conditions in a structurally simple manner.

[0013] Regarding the particularly effective removal of dirt or particles on a planar region or a sensor element, the means can be designed to generate a laminar flow of the medium along the planar region or the sensor element. The characteristic of this laminar flow is its constant flow velocity, which does not exert a sudden pulsed impact on the sensor element or the planar region as in the case of air vortices caused by turbulence, for example. In addition, laminar flow fundamentally prevents dirt and particles from adhering to the planar region or the sensor element. Dirt and particles also include dust and liquids, such as water and oil. In any case, a smooth flow is more conducive to avoiding the generation of lateral forces or bending moments on the planar region or the sensor element, which could otherwise cause vibration of a thin carrier or sensor element. In addition, the movement direction of dirt and particles can be well controlled by laminar flow.

[0014] To ensure the particularly efficient removal of particles or other contaminants, the device may have an adjustment mechanism or a control mechanism for adjusting or controlling the flow and / or flow rate of the medium. Here, a constant flow with a constant flow rate can be adjusted and / or controlled, for example, by using suitable measuring sensors. In addition, in the case where contaminants already exist, a pressure shock or a pulsating flow can be generated by means of an adjustment device to remove the contaminants, which may, for example, due to an interruption in the supply of the medium or compressed air, lead to the formation of deposits that may adhere to the planar area or the sensor element with more or less intensity depending on the material properties, and the contaminants may be generated when there is a sudden large amount of contamination or when the device has been shut down for a long time. Here, the flow can first be at a higher pressure or a higher Reynolds number and then the pressure can be reduced, preferably to the desired flow or flow rate.

[0015] In a specific embodiment, the flow of the medium can be guided transversely to the measuring direction. This ensures that contaminants or particles are specifically removed from the measuring line predefined by the measuring direction. Instead or in addition, the flow of the medium can be guided parallel to the planar area or the sensor element. This ensures that contaminants or particles are reliably guided away from the planar area or the sensor element, without, for example, applying a bending moment to the planar area or the sensor element that would distort the measurement or make it impossible.

[0016] Regarding the particularly reliable operation of the sensor, the device may have a guiding element for the flow of the medium, which is assigned to the carrier, the planar area or the sensor element, and / or the guiding element can be coupled to the carrier, the planar area or the sensor element and can be separated from the carrier, the planar area or the sensor element. Through such a guiding element, the flow of the gaseous medium can be guided particularly reliably. Depending on the design of the guiding element, the medium can be guided along different desired directions by means of the guiding element to remove contaminants or particles from the planar area or the sensor element. Due to the possibility of coupling and separation, the sensor can also be operated without the guiding element as needed. This achieves a high degree of flexibility in the use of the sensor, which can be used both with and without the guiding element. This also enables the addition of a guiding element to the sensor.

[0017] Regarding the particularly reliable generation of flow and thus the reliable operation of the sensor, the guiding element can have an interface for the supply line of the medium. Here, the medium is guided through or by the guiding element to the planar area or the sensor element in a simple and reliably controllable manner.

[0018] Furthermore, with regard to a particularly reliable controlled generation of flow, the guiding element may have a receiving or distributing chamber for the medium, which is in fluid communication with the interface. Such a receiving or distributing chamber may serve as a buffer chamber for the medium and the received medium is controllably guided to a planar area or a sensor element.

[0019] For a reliable guiding of the flow to the planar area or the sensor element, the receiving or distributing chamber may have at least one outlet for the medium. In an implementation with one outlet, all the medium received in the receiving or distributing chamber may be specifically guided along the planar area or the sensor element. In an implementation with two or more outlets, the medium received in the receiving or distributing chamber may be supplied to multiple planar areas of the sensor or sensor elements, so as to enable the medium to flow along more planar areas or sensor elements. In the case of a gap sensor having two sensor elements measuring in opposite directions, the medium may be guided along both sensor elements or along two respective planar areas simultaneously, so as to ensure the removal of dirt or particles. The resulting parallel flow causes the sensor element to be surrounded by two flows in a sandwich-like manner, thereby particularly reliably avoiding bending moments that would damage the measurement of the sensor element.

[0020] Depending on the requirements and design of the planar area or the sensor element, at least one outlet may have a slot, which has at least one guiding rib or multiple channels arranged side by side. In an implementation of the slot (with or without guiding ribs), a wide, thin and flat flow can be achieved. A flat flow can also be reliably achieved through multiple channels arranged side by side.

[0021] The guiding element may be designed as a one-piece or multi-piece component. In a multi-piece design, the guiding element can be adapted to different measurement conditions, such as spatial conditions, in individual ways and methods. The multi-piece design also enables the easy replacement of a damaged component while continuing to use the undamaged parts.

[0022] In a further embodiment, the guiding element may have two half-shells that can be coupled or bolted together, or consist of two half-shells that can be coupled or bolted together. Such half-shells can be assigned to the carrier or the sensor, for example, from different sides and in a very simple manner.

[0023] Here, the carrier can be at least partially arranged between the half-shells in a reliable manner, and / or the half-shells are fixed to the carrier by clamping, thereby achieving a particularly protected arrangement of the carrier by means of the half-shells and a particularly reliable and stable coupling of the carrier with the half-shells or the guiding element.

[0024] Depending on the desired flow direction, the carrier and / or the guiding element and / or the receiving or dispensing chamber can have a curved or bent shape. The curved or bent shape can, for example, have a curvature or an angle of approximately 90° in order to deflect the flow accordingly by approximately 90° from the feed direction.

[0025] In a specific embodiment, the carrier or the planar region can have two sensor elements measured in opposite directions, thereby forming a gap sensor through which the gap width can be measured particularly easily. Generally, the carrier or the plane can have a plurality of sensor elements measured along different directions, wherein the number of sensor elements and directions can also be three or more depending on the application.

[0026] Regarding a particularly simple and reliable structure, the carrier can be designed as having a circuit board or a circuit board. Using a circuit board as a carrier has proven to be feasible in practice and enables the flexible and cost-effective manufacture of sensors.

[0027] Regarding the particularly reliable control and / or transmission of measurement data to the evaluation electronics, the sensor elements can be connected to the evaluation electronics via a coaxial cable or a triaxial cable. A particularly high shielding effect can be achieved with the aid of a triaxial cable.

[0028] Other advantages and aspects of an embodiment of the sensor according to the invention are described below:

[0029] By means of a fixedly installed or also retrofittable guiding element for the medium, a flow or an air flow transverse to the measuring direction can be integrated, which blows away particles or dirt. The two aforementioned half-shells can be designed such that the air flow is designed to be parallel to the sensor surface or the sensor elements.

[0030] The flow can be achieved through the entire sensor surface or the entire sensor element or a plurality of complete sensor elements, if necessary on both sides of the carrier.

[0031] By means of lateral connecting channels in the guiding element, an air chamber or a receiving or dispensing chamber can be generated, which is supplied with air at one point (one interface), however the air chamber or the receiving or dispensing chamber discharges at different openings or outlets. It is irrelevant in this case from which direction the air or the medium is supplied, which can be individually adapted according to the installation situation. For example, compressed air can be supplied through the interface.

[0032] The air flow guiding device or the guiding element can be made from a simple, 3D-printed plastic part to a more complex metal-milled part as required. Here, the air flow guiding device or the guiding element as well as the air chamber or the receiving or dispensing chamber can be formed as a unit.

[0033] In any case, a simple design solution for the exhaust port or outlet at the corresponding desired position can be achieved. In a simple case, the exhaust port or outlet can have a slit nozzle. It is also possible to implement a row of hole nozzles or a slit nozzle with or without a partition in the gap for guiding (preferably laminar) air flow.

[0034] The exhaust ports or outlets on both sides of the gap sensor have the advantage that the unilateral temperature change is not caused by air flow or medium flow and the thin / flexible sensor is not bent in a certain direction. The reason is that air or medium is guided from a common air chamber or a receiving or distributing chamber to both sides. Even if the cooling usually desired for the sensor is caused by the temperature difference between the air or medium and the sensor, this effect is the same on both sides and the sensor in the middle can still remain straight.

[0035] In particular, the slender design solution of the sensor combined with a single interface or an air interface enables a very compact sensor, which can be well applied even in a narrow installation space. Here, the guiding element can be bolted to the sensor, and the sensor can still be installed at its predetermined bolt connection point.

[0036] The guiding element can be adapted to the roller geometry and ensure the additional mechanical stability of a thin sensor, such as a 0.4 mm thin sensor. This can also reduce the tendency of the sensor to swing or vibrate, for example, caused by external vibrations. The guiding element can have a curved surface here.

[0037] The embodiment of the sensor according to the present invention can be used not only for measuring the roll gap, but generally also for gap measurement in a harsh environment where dirt may appear.

[0038] Generally speaking, the sensor can be implemented as a flat sensor for roll gap measurement, which has means for allowing a gaseous medium to flow along the planar area or sensor element of the sensor. Fundamentally speaking, the means for allowing a gaseous medium to flow can also be called a purging device, that is, a device for blowing dirt or particles away from the planar area or sensor element. Description of the Drawings

[0039] Now there are different possibilities to design and further improve the principle of the present invention in an advantageous manner. For this purpose, on the one hand, reference can be made to the dependent claims, and on the other hand, reference can be made to the following description of the preferred embodiments of the sensor according to the present invention. The preferred design and improvement of the principle of the present invention will generally also be elaborated in the description of the preferred embodiments in conjunction with the drawings. Shown in the drawings:

[0040] Figure 1 A first embodiment of the sensor according to the present invention is shown in a perspective view,

[0041] Figure 2 The embodiment in the case of use between two rollers is shown partially cut away in a side view and is from Figure 1 and is in the situation of being used between two rollers.

[0042] Figure 3 The embodiment from Figure 1 is shown in two exploded views, one shown from obliquely above and one shown from obliquely below.

[0043] Figure 4 The embodiment from Figure 1 is shown in a side view, partially cut away, and in a top view.

[0044] Figure 5 A second embodiment of the sensor according to the invention is shown in an exploded view from obliquely above, and

[0045] Figure 6 The second embodiment from Figure 5 is shown in a side view and in a top view.

[0046] In the following embodiments of the sensor according to the invention and designed as a gap sensor 1, the same reference numerals refer to the same elements. Detailed Description

[0047] Figure 1 A first embodiment of the sensor according to the invention and designed as a gap sensor 1 is shown in a perspective view. The sensor includes a substrate or carrier having a planar region 2 and means 3 for causing a gaseous medium to flow along the planar region 2. The means 3 may also be referred to as a purge means 3. The purge means has an interface 4 for the gaseous medium (here air). Other gaseous media may be used instead of air to generate the flow. The interface 4 is designed as a compressed air interface 4 in this embodiment, and a pressure hose (not shown) can be coupled to the compressed air interface. Sensor elements 5a, 5b are arranged on opposite sides of the front end portion of the planar region 2 so as to measure the sensor elements 5a, 5b in opposite directions, for example to determine the gap width. The gap sensor 1 can be supplied with compressed air through the interface 4, so that dirt or particles can be removed from the planar region 2 or the sensor elements 5a, 5b by the flow of air.

[0048] Furthermore, the gap sensor 1 has two electrical interfaces in the form of triaxial cables 6a, 6b for the two capacitive sensor elements 5a, 5b, and the triaxial cables are connected in a connection region 7 on the gap sensor 1.

[0049] Figure 2 The embodiment in the arrangement for measuring the roller gap 8 between two rollers 9a, 9b is shown in a partially cut-away side view and is fromFigure 1 The gap sensor 1. The gap sensor 1 is arranged here on one side of the rolls 9a, 9b in an area where the rolled material (not shown) does not pass through. Here, the planar area 2 with the sensor elements 5a, 5b extends into the roll gap 8. Alternatively, the gap sensor 1 can also be arranged in the area of the roll heads (not shown).

[0050] To avoid collision of the pressure hoses (not shown) with the rolls 9a, 9b, the compressed air connection 4 and the three-axis cable 6 are arranged on the rear side of the gap sensor 1.

[0051] The roll gap 8 is measured by means of the sensor elements 5a, 5b in such a way that the first sensor element 5a measures against the upper roll 9a and the second sensor element 5b measures against the lower roll 9b.

[0052] Figure 3 The gap sensor 1 from Figure 1 is shown in two exploded views, one viewed obliquely from above (A) and one viewed obliquely from below (B). The gap sensor 1 has two sensor elements 5a, 5b, which are arranged on the planar area 2 of the flat carrier or substrate 10. In the connection area 7, the sensor elements 5a, 5b are connected to the three-axis cables 6a, 6b. The purging device 3 has two half-shells 11a, 11b, which together form a guiding element for the gaseous medium (here air). The upper half-shell 11a contains the compressed air connection 4 for the compressed air hose (not shown) and guides the compressed air from above along the carrier or substrate 10 in the direction of the upper sensor element 5a. The lower half-shell 11b supports the carrier or substrate 10 and guides the compressed air from below along the carrier or substrate 10 in the direction of the lower sensor element 5b. The lower half-shell 11b additionally contains a partition 12, which additionally supports the substrate 10. The partition 12 is arranged relative to the air inlet nozzle 13 used as an inlet in the upper half-shell 11a and prevents the substrate 10 from vibrating in the front area due to the impact of the compressed air. The two half-shells 11a, 11b of the purging device 3 are connected to each other by bolts 14a, 14b and are fixed to the carrier or substrate 10 by clamping.

[0053] The half-shells 11a, 11b form a cavity 5 that is in fluid connection with the air inlet nozzle 13. The cavity has a side that is open in the direction of the sensor elements 5a, 5b, thereby forming air discharge nozzles 16a, 16b that serve as outlets respectively. The air inlet nozzle 13 forms an inlet for the cavity 15 here, and the inlet serves as a receiving or distributing chamber for air. Compressed air is guided along the substrate 10 towards the sensor elements 5a, 5b through the air discharge nozzles 16a, 16b, thereby efficiently removing dirt. The substrate 10 includes two mounting bushings 17a, 17b in the connection area 7, whereby the gap sensor 1 can be fixed to an object (not shown here). Alternatively, the fixing can also be carried out by the purging device 3, for example, by constructing bolt connection lugs or mounting bushings there.

[0054] Figure 4 A gap sensor 1 according to a first embodiment from Figure 1 is shown in a partially cut-away side view (A) and in a top view (B). Through the air passage 18 in the preferably coupleable and detachable compressed air interface 4, compressed air is guided through the air inlet nozzle 13 into the cavity 15 and then continues to be guided through the air discharge nozzles 16a, 16b.

[0055] Figure 5 A second embodiment of a sensor in the form of a gap sensor 1 according to the present invention is shown in an exploded view from obliquely above. The sensor has a bent design and has a purging device 19. Here, the carrier or substrate 20 is bent, ideally at an angle of 90°. Thereby, the gap sensor 1 can be arranged such that the sensor elements 5a, 5b extend into a roll gap (not shown here) and the interfaces (cables 6a, 6b, compressed air interface 4) protrude from one side. This avoids interfering with the rolling process. In this example, the half-shells 21a, 21b are designed such that the cavity 22 is also bent and the air discharge nozzles 23a, 23b again guide compressed air in the direction of the sensor elements 5a, 5b. The half-shells 21a, 21b are connected to each other by bolts 14a, 14b. Additionally, the substrate 20 is also connected to the lower half-shell 21b by press-in sleeves 24a, 24b to mechanically fix the substrate. In this example, the lower half-shell 21b is also designed for fixing the sensor 1. For this purpose, a metal angle 25 is formed on the half-shell 21b, and the sensor 1 can be fixed to one side, for example, to a rolling stand (not shown here) by means of the metal angle.

[0056] Figure 6 A gap sensor 1 according to a second embodiment from Figure 5 is shown in a side view (A) and in a top view (B). Through holes or drill holes 26 are provided in the metal angle 25 for fixing to an object (not shown here).

[0057] For other advantageous designs of the sensor according to the invention, reference is made to the general part of the description and the appended claims in order to avoid repetition.

[0058] Finally, it should be clearly pointed out that the foregoing embodiments are only used for discussing the claimed principles and are not limited to these embodiments.

[0059] List of reference signs

[0060] 1 Gap sensor

[0061] 2 Planar area

[0062] 3 Device, purging device

[0063] 4 Interface, compressed air interface

[0064] 5a, 5b Sensor elements

[0065] 6, 6a, 6b Triaxial cables

[0066] 7 Connection area

[0067] 8 Roll gap

[0068] 9a, 9b Rolls

[0069] 10 Carrier, substrate

[0070] 11a, 11b Half shells

[0071] 12 Partition

[0072] 13 Air inlet nozzle

[0073] 14a, 14b Bolts

[0074] 15 Cavity

[0075] 16a, 16b Air outlet nozzles

[0076] 17a, 17b Mounting bushings

[0077] 18 Air channel

[0078] 19 Device, purging device

[0079] 20 Carrier, substrate

[0080] 21a, 21b Half shells

[0081] 22 Cavity

[0082] 23a, 23b Air outlet nozzles

[0083] Press-in sleeves 24a, 24b

[0084] Angle iron 25

[0085] Through hole 26

Claims

1. A sensor for distance or position measurement, in particular a capacitive or inductive sensor or a sensor operating based on eddy currents, having a carrier (10; 20) and sensor elements (5a, 5b), wherein the carrier has a planar region (2) and the sensor elements are arranged on or integrated in the planar region (2). It is characterized in that A device (3) for causing a gaseous medium to flow along the planar region (2) or the sensor element (5a, 5b) is assigned to the carrier (10; 20), the planar region (2) or the sensor element (5a, 5b).

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

3. The sensor according to claim 1 or 2, characterized in that The device (3) has an adjustment mechanism or a control mechanism for adjusting or controlling the flow and / or the flow rate of the medium.

4. The sensor according to any one of claims 1 to 3, characterized in that The flow of the medium is guided transversely to the measuring direction and / or parallel to the planar region (2) or the sensor element (5a, 5b).

5. The sensor according to any one of claims 1 to 4, characterized in that The device (3) has a guiding element for the flow of the medium, which guiding element is assigned to the carrier (10; 20), the planar region (2) or the sensor element (5a, 5b), and / or the guiding element can be coupled to the carrier (10; 20), the planar region (2) or the sensor element (5a, 5b) and can be separated from the carrier (10; 20), the planar region or the sensor element (5a, 5b).

6. The sensor according to claim 5, characterized in that The guiding element has an interface (4) for a supply line of the medium.

7. The sensor according to claim 5 or 6, characterized in that The guiding element has a receiving or distributing chamber (15; 22) for the medium, which is in fluid communication with the interface (4).

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

9. The sensor according to claim 8, characterized in that The at least one outlet (16a, 16b; 23a, 23b) has a slot which has at least one guiding rib (12) or a plurality of channels arranged side by side.

10. The sensor according to any one of claims 5 to 9, characterized in that The guiding element is designed in a multi-piece manner.

11. The sensor according to any one of claims 5 to 10, characterized in that The guiding element has two half-shells (11a, 11b; 21a, 21b) which can be coupled or bolted together or consists of two half-shells (11a, 11b; 21a, 21b) which can be coupled or bolted together.

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

13. The sensor according to any one of claims 1 to 12, characterized in that The carrier (20) and / or the guiding element and / or the receiving or distributing chamber (22) has a curved or bent shape.

14. The sensor according to any one of claims 1 to 13, characterized in that The carrier (10; 20) or the planar region (2) has two sensor elements (5a, 5b) measured in opposite directions, thereby forming a gap sensor (1).

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