Device and method for cleaning deposits and deposits on an end plate of a sensor body

Abstract

Device for cleaning deposits and deposits on an end plate (2) of a sensor body (1), wherein the sensor body (1) is designed to accommodate a measuring device (6) for Determination of one or more physical and / or chemical process variables, wherein the sensor body (1) is designed to be liquid-tight and wherein a wiper (3) with a wiper blade (4) is provided for cleaning the end plate (2), characterized by that the wiper (3) is arranged as a subcomponent on a peripheral attachment module (7), wherein the geometries of the wiper (3) and the peripheral attachment module (7) are designed such that the wiper (3) moves from a rest position to a cleaning position and back to the rest position during a continuous unidirectional rotational movement in the course of one revolution, wherein in the rest position the upper edge of the wiper (3) is flush with the upper edge of the end plate (2), wherein the wiper (3) rises upwards during the rotary movement from the rest position along the sensor body longitudinal axis (LA) and reaches the maximum height in the cleaning position and thus the lower edge of the wiper blade (4) is flush with the upper edge of the end plate (2), and the wiper (3) cleans the end plate (2) through contact of the wiper blade (4).

Description

[0001] The invention relates to a device and a method for cleaning deposits and build-up on an end plate of a sensor body, wherein the sensor body is designed to accommodate a measuring device for determining one or more physical and / or chemical process variables, wherein the sensor body is designed to be liquid-tight and wherein a wiper with a wiper blade is provided for cleaning the end plate.

[0002] Sensors within the meaning of this invention serve to determine process variables in liquids, particularly fresh and process water, as well as gases. Examples of typical process variables are turbidity, solids content, or sludge level. However, embodiments allow for other chemical and physical process variables. Examples include the determination of nitrate content, UV absorption, pressure measurement, or non-contact level measurement, particularly using ultrasound. Measuring instruments suitable for determining the corresponding process variables are offered and distributed by the Endress+Hauser Group in a wide variety of models.

[0003] Typically, the sensors are arranged in a sensor body. Many of the aforementioned process variables are determined optically. Electromagnetic waves of a specific wavelength are received through an optical window in the sensor body. DE 42 33 218 C2 discloses a device for turbidity measurement, which additionally provides an optical source connected to the sensor body via another optical window.

[0004] From EP 1 816 462 B1 an arrangement is known in which only one window is provided for source and receiver.

[0005] If the process variables are determined non-optically, the sensor is in contact with the medium via a membrane or a corresponding matching layer.

[0006] Operation in aqueous or gaseous media, especially wastewater, can lead to incrustations, contamination, deposits, and buildup on the optical window or membrane, which can distort measurement results or make measurement impossible. The Endress+Hauser Group's "Technical Information TurbiMax W CUS41 / CUS41-W" brochure states that windows can be cleaned using a wiper mounted on the end plate of the sensor body.

[0007] The wiper is driven by a motor in the sensor body, with the movement transmitted via a shaft. Care must be taken to ensure that the point where the shaft passes through the sensor body is sealed for long-term stability to prevent any medium from penetrating the sensor body.

[0008] The movement of the wiper is controlled by a control unit and occurs alternately clockwise and counterclockwise.

[0009] To avoid incorrect measurements, the wiper must be placed in a defined rest position after cleaning, positioned far enough away from the windows. If the wiper is positioned close to the measuring device, the measurement will be disturbed and distorted by the wiper.

[0010] US 2009 / 0 229 067 A1 discloses a wiper for an optical surface of a device. The wiper comprises a blade with an edge that is rigid and non-deformable to withstand high shear stresses. The blade is configured to rotate about a first axis parallel to the optical surface and is configured to move in a line with respect to a second axis perpendicular to the optical surface.

[0011] EP 1 816 462 B1 discloses a wastewater submersible probe with an optical window that is cleaned by a wiper. The rotating wiper cleans the outside of the sensor window with oscillating wiping movements. The wiper is not connected via a shaft, but via a magnetic coupling to an electric drive motor located inside the housing.

[0012] The present invention is based on the object of proposing a device and a method which ensures reliable cleaning of the end plate of a sensor body.

[0013] The problem is solved by the features of claim 1.

[0014] The following advantages are evident when arranging the wiper on a peripheral add-on module according to the invention: - No shaft needs to penetrate the end plate, minimizing the risk of leaks. - In its resting position, the wiper is sufficiently far away from the surface of the end plate, and thus from the measuring device. This means that the wiper does not interfere with the measurement. - The peripheral add-on module can also be retrofitted to any sensor body. This means the wiper is optional. A peripheral add-on module can be added depending on customer requirements. The sensor body remains the same whether a wiper is installed or not, which helps keep production costs low.

[0015] In a preferred embodiment, the wiper moves orthogonally to the surface of the end plate from its rest position to the cleaning position and the wiper returns orthogonally to the surface of the end plate from the cleaning position to the rest position.

[0016] In an advantageous embodiment, an optical measuring device is provided in the sensor body, and at least one optical window is located in the end plate. Especially with optical measuring devices, it is necessary that the optical windows, which protect the measuring device from the medium, are cleaned regularly to ensure accurate measurement.

[0017] Positioned beneath the optical windows is the optical measuring device, which may comprise one or more optical components, such as optical sensors. In a preferred embodiment, each optical component has its own optical window. However, it is also conceivable to use a common optical window for all optical components.

[0018] Optical sensors within the meaning of this invention are sensors for determining turbidity, sludge level, or solids content. In addition to the sensors mentioned, other optical sensors, such as sensors for determining nitrate content, UV absorption, certain pressure sensors, or level sensors that operate according to the ultrasonic principle, can also be cleaned with the device according to the invention.

[0019] The wavelengths of the electromagnetic waves of the optical components are typically in the near infrared, for example at 880 nm.

[0020] Designs are possible in which the process variables are determined non-optically, for example, pressure sensors. The sensor is in contact with the medium via a membrane or a corresponding matching layer.

[0021] The rotary movement of the wiper can be controlled manually, but a motor is preferably used as the drive. This ensures that the start and stop times, speed, number of revolutions, and direction of movement can be precisely adjusted and controlled. The motor's power is transmitted to the wiper via a shaft. It is also conceivable for the power transmission to occur through non-rigid connections or without a shaft, for example, through the use of a magnetic actuator.

[0022] The motor moves the wiper unidirectionally, either clockwise or counterclockwise. The geometry of the wiper and the peripheral attachment module makes it possible to clean the end plate, even when the wiper only rotates in one direction. Of course, the motor can rotate in both directions and is also capable of a back-and-forth motion.

[0023] In an advantageous embodiment, a first detector element is located in the area of ​​the underside of the wiper, and a second, corresponding detector element is located in the area of ​​the top side of the peripheral attachment module. These detector elements can be used to determine the position and movement of the wiper, in particular the number of revolutions of the wiper.

[0024] A control unit is advantageously used. The control unit can determine and control the number, duration, direction, and speed of the wiper's rotations. This allows the user to determine how long, how quickly, and / or how often the end plate should be cleaned.

[0025] In a preferred embodiment, the geometry of the wiper and the peripheral attachment module is designed such that the wiper returns to its rest position automatically or under forced movement after cleaning is complete. When the wiper returns to its rest position in this way, it is always ensured that the wiper is far enough away from the measuring device during measurement phases and does not interfere with the measurement.

[0026] Preferably, a spring element is arranged inside the peripheral attachment module. This spring element retracts the wiper to the rest position or holds it in that position. The presence of the spring element has a beneficial effect on the quality of the measurement, as it keeps the wiper at a distance from the measuring device during measurement phases, holds it there, and does not interfere with the measurement.

[0027] The end plate is arranged either orthogonally or at an angle other than 90° to the sensor body's longitudinal axis. The latter design is advantageous because the measuring device can be installed in conventional pipelines or elsewhere, protected from shock and less susceptible to contamination.

[0028] The geometry of the peripheral add-on module and its arrangement on the sensor body, in particular the height difference between the upper edge of the peripheral add-on module and the upper edge of the end plate, i.e., the height of the wiper, is designed such that the deposits and residues on the wiper that accrue during cleaning are removed by overcoming the height difference. The edge of the end plate is designed as a "sharp" edge, i.e., the edge of the end plate is rectangular or acute-angled, so that the contaminants that the wiper has removed from the end plate are removed from the wiper blade, allowing the next cleaning process to begin with a "clean" wiper blade.

[0029] The object is achieved with regard to the method according to the invention by the features of claim 12.

[0030] In one embodiment, the wiper is guided from the rest position to the cleaning position by the geometry of the wiper and the peripheral attachment module, with the wiper following a trajectory defined by the geometry of the wiper and the peripheral attachment module. The wiper or wiper blade cleans the surface of the end plate of the sensor body and then returns to the rest position.

[0031] In an alternative embodiment, the wiper is moved from the rest position to the cleaning position only by an axis, shaft or similar, the wiper or wiper blade cleans the surface of the end plate, and the wiper then returns to the rest position.

[0032] Advantageously, the wiper automatically returns to its rest position when force is applied. When the wiper returns to its rest position in this way, it is always guaranteed that the wiper is far enough away from the measurement and does not interfere with the measurement.

[0033] The wiper is held in the rest position and the drive must overcome the force in order for the wiper to move from the rest position to the cleaning position.

[0034] The invention is explained in more detail with reference to the following figures. Fig. 1 a perspective view of a sensor body with peripheral add-on module and wiper in rest position, Fig. 2 a side view of a sensor body with peripheral add-on module and wiper in an intermediate position, Fig. 3 a perspective view of a sensor body with peripheral add-on module and wiper in cleaning position, and Fig. 4 a cross-section through a sensor body with peripheral add-on module and wiper in rest position.

[0035] In the figures, identical features are identified by identical reference numerals.

[0036] Fig. Figure 1 shows a sensor body 1 sealed in a liquid-tight manner by an end plate 2. The end plate 2 is connected to the sensor body 1, for example, by screwing, gluing, or locking. The sensor body 1 and the end plate 2 are made of stainless steel, for example. Depending on the application, versions made of hard plastic, particularly PVC, POM, or PPS GF 40, are conceivable. The sensor body 1 and end plate 2 are preferably designed for permanent immersion in liquids, particularly wastewater, or gases.

[0037] The sensor body 1 typically has the shape of a right circular cylinder; the end plate 2 is positioned orthogonally to the sensor body's longitudinal axis LA. However, other embodiments are conceivable: Furthermore, it should be noted that the end plate 2 can be arranged at an angle other than 90° to the sensor body's longitudinal axis LA.

[0038] The embodiment in the figures Fig. 1- Fig. Figure 4 shows a measuring device for determining optical process variables. This can be used, for example, to determine turbidity, sludge level, or solids content. However, the device according to the invention can also be used to clean the end plate of a sensor body with a measuring device for non-optical process variables.

[0039] Six optical windows 5 are located on the end plate 2. An optical measuring device 6 located underneath transmits and receives electromagnetic waves, typically at near-infrared wavelengths, through the windows 5. The windows 5 are made of sapphire glass, for example.

[0040] In the Fig. In the embodiment shown in Figure 1, the optical measuring device 6 consists of six optical components. Each optical component transmits / receives through its own optical window with the medium. However, it is also conceivable for the optical components to transmit and receive through a common window.

[0041] The optical measuring device 6 has two independently functioning sensor units, each with a light source and two light receivers. The two light receivers are preferably used to receive scattered light at an angle of 90° and 135° to the beam direction of the light source, respectively. For example, in a turbidity sensor, the 90° channel is preferably used for low turbidity values. For medium and high turbidity values, as well as for solid measurements, the 135° channel is preferably used. Other embodiments have fewer, or possibly more, optical components.

[0042] For example, a sensory unit with a light source and a light receiver at an angle of 90° and 135° is conceivable.

[0043] A peripheral add-on module 7 is located on the sensor body 1. The peripheral add-on module 7 is firmly connected to the sensor body 1 by screwing, gluing, welding, or similar means. It should be noted that the peripheral add-on module 7 can also be retrofitted to the sensor body 1; in this case, the peripheral add-on module 7 is clipped to the sensor body, e.g., using an adapter piece, and secured as described above. The peripheral add-on module 7 is made, for example, of a plastic such as POM.

[0044] A wiper 3 is arranged on the peripheral attachment module 7. The wiper 3 is made of hard plastic or metal, for example. A wiper blade 4 is attached to the underside of the wiper 3. The wiper blade 4 serves to clean the end plate 2 and is made of plastic, rubber, or the like, for example. The wiper blade 4 is attached to the wiper 3 by joining, in particular by gluing.

[0045] In the resting position, as in Fig. 1, the upper edge of the wiper 3 is flush with the upper edge of the end plate 2.

[0046] Corresponding detector elements 10a and 10b are located in the area of ​​the underside of wiper 3 and in the area of ​​the top of peripheral add-on module 7. Each time wiper 3 or detector element 10a passes over peripheral add-on module 7 or detector element 10b, a rotation is detected.

[0047] Fig. Figure 4 shows a cross-section through the sensor body 1 in the resting position. The optical measuring devices 6 are located below the windows 5. A drive 9 transmits its power to the wiper 3 via a shaft 8. The drive can be manual, but typically a motor is used. The drive is unidirectional, counterclockwise. Of course, embodiments in which the drive 9 rotates clockwise are also possible.

[0048] The drive 9 is controlled by a control unit 12. The control unit 12 controls the number of revolutions, the speed, the direction of movement and / or the duration of the wiper 3. The detector elements 10a and 10b provide information about the position and / or movement of the wiper 3.

[0049] In the peripheral attachment module 7, above the drive 9 and around the shaft 8, there is a spring element 11. This spring element 11 causes the wiper 3 to be retracted to its rest position or held there. The drive 9 must overcome this restoring force to move the wiper 3 away from the rest position. Furthermore, the wiper 3 or wiper blade 4 exerts a defined contact pressure on the end plate 2 during cleaning thanks to the spring element 11.

[0050] The restoring force can also be applied by components other than a spring element 11, e.g. by magnetic elements attached to the wiper 3 and the peripheral attachment module 7.

[0051] The characters Fig. 1- Fig. 3 show the cleaning process from the rest position ( Fig. 1) via an intermediate position ( Fig. 2) towards a cleaning position ( Fig. 3). After cleaning is complete, wiper 3 returns to the rest position ( Fig. 1).

[0052] Fig. Figure 2 shows the sensor body 1 with the peripheral attachment module 7 in a side view. If the drive 9 moves unidirectionally counterclockwise, the wiper 3 is set into a rotational movement via the shaft 8. The geometry of the wiper 3 and the peripheral attachment module 7 determine the trajectory, i.e., the spatial curve, of the wiper 3 during the movement: The further the wiper 3 moves away from the rest position due to the rotational movement, the further the wiper rises in the direction of the sensor body's longitudinal axis LA.

[0053] In the Fig. 2, the upper edge of the wiper 3 is located above the upper edge of the end plate 2. As already mentioned, this is realized by the special design of the wiper 3 and the peripheral attachment module 7. In the rest position ( Fig. 1), however, the upper edge of the wiper 3 is flush with the upper edge of the end plate 2.

[0054] In the cleaning position in Fig. 3, the wiper blade 3 reaches its maximum height. In the cleaning position, the lower edge of the wiper blade 4 is then flush with the upper edge of the end plate 2.

[0055] The end plate 2 is cleaned by the continuous, unidirectional movement of wiper 3 or wiper blade 4. Depending on the type of sensor, one or more windows 5, possibly also membranes or matching layers, are located on the end plate, which are also cleaned in this way. It is also possible for wiper 3 to perform a back-and-forth movement.

[0056] After passing over the end plate 2, the wiper 3 falls back into the rest position on the peripheral attachment module 7. In addition to the drive-controlled movement of the wiper 3, this is done with the help of the spring element 11, which retracts the wiper 3 through its restoring force and allows the wiper 3 to snap back into its rest position.

[0057] By overcoming the height difference between the upper edge of the end plate 2 and the upper edge of the peripheral attachment module 7, the deposits and buildup on the wiper 3 and the wiper blade 4 are removed. This is supported by a sharp design of the edge of the end plate 2.

[0058] Thus, one rotation of the wiper 3 is completed. The detector elements 10a and 10b detect the end of a rotation. The control unit 12 controls the number of rotations, the duration of cleaning, the direction of movement and / or the speed of the wiper 3. For example, it is also conceivable that after a specified time, the wiper 3 changes its direction of movement. In the embodiment shown in the figures Fig. 1- Fig. In the configuration shown in Figure 4, this means a change in direction from the original counterclockwise to a clockwise direction. Due to the geometry of wiper 3 and the peripheral attachment module 7, wiper 3 moves back to its rest position, where it is detected by detector elements 10a and 10b.

[0059] A cleaning process consists of at least one rotation, but any number of rotations or a time period can be set.

Claims

[1] Device for cleaning deposits and deposits on an end plate (2) of a sensor body (1), wherein the sensor body (1) is designed to accommodate a measuring device (6) for Determination of one or more physical and / or chemical process variables, wherein the sensor body (1) is designed to be liquid-tight and wherein a wiper (3) with a wiper blade (4) is provided for cleaning the end plate (2), characterized by , that the wiper (3) is arranged as a subcomponent on a peripheral attachment module (7), wherein the geometries of the wiper (3) and the peripheral attachment module (7) are designed such that the wiper (3) moves from a rest position to a cleaning position and back to the rest position during a continuous unidirectional rotational movement in the course of one revolution, wherein in the rest position the upper edge of the wiper (3) is flush with the upper edge of the end plate (2), wherein the wiper (3) rises upwards during the rotary movement from the rest position along the sensor body longitudinal axis (LA) and reaches the maximum height in the cleaning position and thus the lower edge of the wiper blade (4) is flush with the upper edge of the end plate (2), and the wiper (3) cleans the end plate (2) through contact of the wiper blade (4). [2] The device according to claim 1, wherein the wiper (3) moves orthogonally to the surface of the end plate (2) from the rest position to the cleaning position and the wiper (3) returns orthogonally to the surface of the end plate (2) from the cleaning position to the rest position. [3] Device according to claim 1 or 2, wherein an optical measuring device (6) is provided and wherein at least one optical window (5) is arranged on the end plate (2). [4] Device according to one of claims 1-3, wherein a motor is provided as a drive (9) for the rotary movement of the wiper (3), and wherein the motor transmits its power to the wiper (3) via a shaft (8). [5] Device according to one of claims 1-4, wherein the motor moves the wiper (3) unidirectionally, i.e. either clockwise or counterclockwise. [6] Device according to one of claims 1-5, wherein a first detector element (10a) is mounted in the area of ​​the underside of the wiper (3) and a second, corresponding detector element (10b) is mounted in the area of ​​the top side of the peripheral attachment module (7), which are provided for determining the position and / or movement of the wiper (3), in particular the number of revolutions of the wiper (3). [7] Device according to one or more of the preceding claims, wherein a control unit (12) is provided, which determines and / or controls the number of revolutions, duration of movement, direction of movement and / or speed of the wiper (3). [8] Device according to one or more of the preceding claims, wherein the geometry of the wiper (3) and the peripheral attachment module (7) is designed such that the wiper (3) automatically returns to the rest position after cleaning has been completed, or returns to the rest position under forced guidance. [9] Device according to one or more of the preceding claims, wherein a spring element (11) is arranged in the peripheral attachment module (7) so that that the spring element (11) retracts the wiper (3) into the rest position or holds the wiper (3) in the rest position. [10] Device according to one or more of the preceding claims, wherein the end plate (2) is arranged either orthogonally or at an angle other than 90° to the sensor body longitudinal axis (LA). [11] Device according to one or more of the preceding claims, wherein the geometry of the peripheral attachment module (7) and its arrangement on the sensor body (1), in particular the height difference between the upper edge of the peripheral attachment module (7) and the upper edge of the end plate (2), ie the height of the wiper (3), are designed such that the deposits and deposits on the wiper (3) arising during cleaning are detached by overcoming the height difference. [12] Method for cleaning deposits and deposits from an end plate of a sensor body (1), wherein the sensor body (1) is designed to accommodate a measuring device (6) for Determination of one or more physical and / or chemical process variables, wherein the sensor body (1) is designed to be liquid-tight and wherein a wiper (3) with a wiper blade (4) is provided for cleaning the end plate (2), characterized by , that the wiper (3), which is arranged as a subcomponent on a peripheral attachment module (7), during continuous unidirectional rotary movement, it is moved from a rest position to a cleaning position in the course of one revolution, the end plate (2) is cleaned by contact of the wiper blade (4), wherein in the rest position the upper edge of the wiper (3) is flush with the upper edge of the end plate (2), wherein the wiper (3) rises upwards during the rotary movement from the rest position along the sensor body longitudinal axis (LA) and reaches the maximum height in the cleaning position and thus the lower edge of the wiper blade (4) is flush with the upper edge of the end plate (2), and the wiper (3) is then moved back to the rest position. [13] Method according to claim 12, wherein the wiper (3) automatically returns to the rest position under the action of force and / or is held in the rest position, and wherein a drive (9) must overcome this force in order for the wiper (3) to be moved from the rest position into the cleaning position.

Images