RADAR MEASURING DEVICE, MEASURING ARRANGEMENT AND LENS

Description

[0001] The present invention relates to a radar measuring device, in particular a radar level measuring device, a measuring arrangement comprising a radar measuring device 1 in a receptacle and a lens for such a radar measuring device.

[0002] Radar measuring instruments are well known for measuring the fill level or limit level of a medium in a process environment, e.g., a pipe, a container, or the like. Such radar measuring instruments have antenna systems that radiate into the process environment via lenses, or couple radar waves to a rod or cable probe (guided wave).

[0003] Radar measuring devices, such as radar level gauges, are known from the state of the art. These devices use the time-of-flight principle to detect the level of a medium, particularly liquids and bulk materials, in a container. Such radar level gauges are equipped, for example, with horn antennas and / or lenses, through which a coupled RF signal is radiated toward the medium and reflected by it. The signals reflected from the medium are recorded and evaluated in a combined transmit and receive system of the radar level gauge.

[0004] Horn antennas generally have a simple and robust design, a very good efficiency and are inexpensive to manufacture.

[0005] For beam shaping, it is known that such horn antennas can have a dielectric lens at the front end of the antenna horn, in the main radiation direction. The electromagnetic waves, which essentially propagate in the antenna horn in a spherical segment shape, are thus converted into wavefronts that are as parallel as possible and propagate in the main radiation direction, thus achieving a directional effect of the antenna.

[0006] Beamforming can also occur during the generation of a transmitted signal and / or during the reception of a received signal if a plurality of transmitters and / or receivers, usually arranged in an array, are used as the transmitting and / or receiving element. This is then referred to as digital beamforming.

[0007] In particular, FMCW radar measuring devices (FMCW: Frequency Modulated Continuous Wave) can be used, which can also detect the topology of a surface or the position of an object. One application example is level measurement in closed or open containers, and in particular, the determination of bulk material quantities. The FMCW radar measuring devices can have array antenna devices with a plurality of antenna elements, e.g., in the form of planar radiator elements. The array antenna device is configured to transmit the FMCW transmission signal toward the object and to receive a corresponding, reflected reception signal. These can be combined transmit and receive antennas or separate transmit and receive antennas.The FMCW transmit signal is a frequency-modulated continuous wave signal in which the transmit frequency is changed within a frequency band during a measurement, typically in the form of a continuous or stepped ramp.

[0008] With such an FMCW radar measuring device, it is possible to carry out so-called digital beamforming in order to scan a spatial area with the transmitted signal, so that a surface topology in the scanned spatial area can be calculated from the reflected received signal.

[0009] It should be noted at this point that for the sake of simplicity, we will refer to radar level gauges or radar level gauges in the following. However, the features described in relation to radar level gauges and radar level gauges apply equally to radar-based level gauges, point level gauges, interface gauges, and topology-detecting radar level gauges.

[0010] To accommodate such a radar level measuring device, the process environment, such as a container, has a receptacle, which can be designed, for example, as a clamp or pipe fitting. Receptacles in the form of adapters are also known in the prior art, which adapt a process connection of the radar level measuring device to a receptacle available or usable in the process environment.

[0011] A measuring arrangement comprising a radar level measuring device 1 and a recording 5 according to the prior art is shown in Figure 1 shown.

[0012] As can be seen from the sectional view in Fig. 1 As can be seen, according to the present exemplary embodiment, the radar measuring device 1 is designed as a radar level measuring device 1 and the receptacle 5 is designed as a flange 5 on an opening in a container wall of a container 2.

[0013] The radar level measuring device 1 has, in a rearward area in the main radiation direction H, radar electronics 1a, which, among other things, generates transmitted signals for radiation into the container 2 and processes radar signals reflected and received by, for example, a filling material in the container 2. Extending from the radar electronics 1a, a process connection 3 extends toward the interior of the container 2, wherein the process connection 3 is formed integrally with a horn antenna for radiation and reception of the radar waves. The front section of the horn antenna is closed off with a dielectric lens 16. The process connection 3, with the lens 16 arranged thereon, projects into a through-opening 4 formed in the wall of the container 2.

[0014] To enable a stable arrangement of the radar level gauge 1 in the through-opening 4, a flange 5 is formed in or arranged on the wall of the container 2. The flange 5 preferably protrudes outward from the container 2 in order to form the through-opening 4 with a larger guide and contact surface.

[0015] The flange 5 also serves to fasten the radar level measuring device 1 to the container 2. In the embodiment shown, the flange 5 has a threaded bore 6 in its outer circumferential area, into which a clamping screw 7 can be screwed to tighten the radar level measuring device 1. The radar level measuring device 1 has a driver 8 on an outer circumference of the process connection 3, which is engaged by a clamping clamp 9, wherein the clamping clamp 9 is fastened to the flange 5 with the aid of the clamping screw 7. Depending on the thickness of a seal 10 and / or the length of the measuring device nozzle relative to the position of the driver 8 on the peripheral wall, the driver 8 can also serve as a stop for a desired end position, as is exemplified by the driver 8 resting on the flange 5.

[0016] In the illustrated embodiment, the flange 5 is welded into the wall of the container 2. This enables a particularly smooth surface in the area of the container interior 2a, since after welding the flange 5, the wall of the container 2 can be smoothed and polished. However, other forms of fastening in the receptacle 5 are also possible, e.g., by means of a union nut that engages an external thread on the flange 5, a screw-in thread by means of which the radar measuring device 1 can be screwed into an internal thread of the flange 5, or various adaptations, depending on the process requirements.

[0017] The inside of the through-opening 4 and the outside of the radar level gauge 1 have a special shape in the transition area or adjacent area to the container interior 2a of the container 2 for accommodating one or more sealing elements. This serves to enable particularly stable mounting of the radar level gauge 1 in the through-opening 4, while simultaneously enabling a smooth surface of the container interior 2a even in the transition area to the front side of the radar level gauge 1. In particular, a seal 10 in the form of a substantially commercially available O-ring can be used.

[0018] The inner wall of the through-opening 4 is designed such that it extends through the through-opening 4 toward the container interior 2a in a direction parallel to a main radiation direction H of the radar level measuring device 1. This means that the through-opening 4 tapers toward the container interior 2a, forming an opening wall 18 that projects into the through-opening 4. In other words, the flange 5 widens toward the container interior 2a, leading into the through-opening 4, for example in the form of a small canopy.

[0019] The inclination or steepness of the wall 18 projecting into the through-opening 4 toward the container interior 2a is dimensioned such that an abutment is formed for a seal 10 clamped between this wall 18 and a driver 13 of the radar level gauge 1. Furthermore, the inclination is selected such that the seal 10 pressed against this wall 18 is pressed toward a gap-shaped spacing region 14 formed between the inner wall of the through-opening 4 in the area adjacent to the container interior 2a and the outer periphery of the radar level gauge 1, in this case the lens 16.

[0020] In order to avoid complex machining of the container 3 or the container wall and / or the flange 5 in this area, various adapters have become established in the prior art, which on the one hand have the previously described design of the through-opening 4 and can be connected to the container 2 via a standardized connection mechanism. Examples include the so-called clamp connection (DIN 32676, ISO 2852), pipe fitting DIN 11851, pipe fitting DIN 11864-1, aseptic connection F40 with grooved union nut, aseptic connection with clamping flange, DRD connection, SMS connection, Neumo Biocontrol connection or Varivent adapter and others.

[0021] The radar level measuring device 1 has in its front section, in the present case in the region of an outer circumference of the lens 16 in the transition region to the container inner side 2a, a circumference which is designed to be so narrower than a diameter of the through opening 4 there that a spacing region 14 is formed.

[0022] At a distance from the container interior 2a, the radar level gauge 1 has a driver 13 for the seal 10. The driver 13 is formed here as an integral component of the lens 16. The driver 13, the peripheral wall of the lens 16 located in front of it, as well as the inner wall of the through-opening 4 and the wall section of the opening wall 18 projecting into the through-opening 4 form a space 5 for receiving the seal 10.

[0023] When the radar level measuring device 1 is inserted into the through-opening 4, the seal 10 located in this area is clamped and pressed or compressed by the driver 13 towards the inner side 2a of the container and the opening wall 18 projecting into the through-opening 4. In particular, due to the inclination of the opening wall 18 of the flange 5 projecting into the through-opening 4 or the container wall of the container 2, the seal 10 is pressed into the spacing area 14 between the opening wall 18 projecting into the through-opening 4 and the outer circumference of the radar level measuring device 1, in this case the lens 16. The seal 10 is not only pressed into the spacing area 14, but is also pressed up to the inner side 2a of the container or, preferably, slightly swells into the interior of the container 2.The opening wall 18 projecting into the through opening 4 projects obliquely in the direction of the spacing area 14, so that the projecting opening wall 18 serves as an abutment and at the same time as a guide element for the pressed-on seal 10.

[0024] In the present embodiment, the lens 16 is centrally connected to a filling 54 of the horn antenna 50 via a threaded bolt that is integrally formed on the lens 16.

[0025] From CN 210 664 669 U a radar measuring device is known in which a radar dome is screwed to a horn antenna.

[0026] US 2008 / 204351 A1 discloses a mounting device for a radar level sensor antenna for detachably mounting a dielectric insert in the antenna. The mounting device can be a continuous clamping ring that clamps the dielectric insert in place within the antenna. Spring-loaded balls can also be used.

[0027] The object of the present invention is to provide a radar measuring device, in particular a radar level measuring device, with improved handling. Furthermore, a measuring arrangement formed from such a radar measuring device and a mount, as well as a lens for such a radar measuring device, are to be provided.

[0028] This object is achieved by a radar measuring device, in particular a radar level measuring device, having the features of patent claim 1, a measuring arrangement having the features of patent claim 14 and by a lens for a radar measuring device having the features of patent claim 16.

[0029] Advantageous embodiments and variants of the invention emerge from the dependent claims and the following description. The features listed individually in the dependent claims can be combined with each other in any technically reasonable manner, as well as with the features explained in more detail in the following description, and represent other advantageous embodiments of the invention.

[0030] A radar measuring device according to the invention, in particular a radar level measuring device, has a housing and is sealingly connectable to a receptacle. The housing is designed as a process connection on the front side, and a dielectric lens is arranged on the housing on the front side and connected to the process connection in such a way that the lens is fixed relative to the housing in the axial direction, in particular in the direction of a main radiation direction of the radar measuring device. According to the invention, the radar measuring device is characterized in that a positive connection is formed between the lens and the process connection.

[0031] Radar level measuring devices are based on the principle of time-of-flight measurements. Time-of-flight measurements determine the signal propagation times of emitted measurement signals, particularly radar signals. These signal propagation times are then used to determine the desired measured value, such as a level or limit level.

[0032] The process environment is defined as the space in which a medium is located, whose level, limit level, boundary layer, or topology is to be determined. The process environment can be, for example, a vessel in the form of a tank, container, pipe, or silo, where the radar measuring device is installed. The vessel itself can have a mount for the radar measuring device, or a flange or nozzle to which the radar measuring device is attached using an adapter.

[0033] In this application, the term "adapter" refers to components that adapt, i.e., adjust, the process connection of the radar measuring device to a receptacle of the process environment. For example, the process connection can be designed as a screw-in thread, and the adapter can be used to connect, for example, to another screw-in thread or a clamp receptacle (DIN 32676, ISO 2852). Other connection options include pipe fittings according to DIN 11851, pipe fittings according to DIN 11864-1, aseptic connection F40 with grooved union nut, aseptic connection with clamping flange, DRD connection, SMS connection, Neumo Biocontrol connection, or Varivent adapter.

[0034] The housing of the radar measuring device can be made up of one or more parts and generally serves to protect the components arranged in the housing, for example electronics for signal processing and an optional display and / or operating module. The fact that the front part of the housing is designed as a process connection means that the front part of the radar level measuring device is designed so that it can be connected to a process environment. The process connection can be formed integrally with the housing or connected to it. The process connection is generally made from a material selected to suit the process environment, e.g. one that is mechanically and chemically resistant, e.g. a suitably alloyed stainless steel such as 1.4404 (316L) or 2.4602 (Hastelloy C-22) or PEEK or ceramic. For the rear part of the housing, cheaper materials can often be used due to the lower chemical and mechanical requirements there, e.g.Plastics or sheets, for example made of a lower alloy steel, can be used.

[0035] A process connection typically refers to the part of a field device that allows it to be arranged in a process environment. The process connection thus represents the mechanical interface between the field device and the process environment.

[0036] The primary radiation direction is the direction in which the radar measuring device emits the most radiation due to the directivity of the antenna used or due to beam-shaping measures without digital beamforming. For radar level measuring devices, this is usually a surface normal to a plane formed by the end of the process connection facing the process environment.

[0037] The connection between the lens and the process connection is preferably circumferential, i.e. in an area located on the circumference of the lens. This means in particular that the positive connection is preferably arranged in an area not directly irradiated when the radar radiation is emitted and therefore has no negative effects on the beam-shaping effect of the lens. In other words, a lens-side part of the positive connection is arranged essentially on the outside of the lens in the radial direction. This means in particular that the connection between the dielectric lens and the process connection, starting from an outer circumference of the dielectric lens, is made no further than 10% of a radius of the dielectric lens inwards. The radius of the dielectric lens results from the process connection and the thickness of the seal used, as well as the shape of the protruding opening wall.This influences the shape of the seal.

[0038] The lens is arranged on the front side of the process connection, i.e., in particular, the lens can be arranged sectionally within the process connection, but is essentially located on the front side, i.e., in the direction of the main radiation direction, at an end of the process connection facing the process environment. The lens is inserted into the process connection from the front or arranged on it. The lens has, at least in sections, a diameter that is larger than a front-side inner diameter of the process connection. In other words, a diameter of the lens is larger, at least in one area, than a clear width of the process connection, so that the lens abuts the front side of the process connection and cannot be pushed through it. Such an arrangement also has the advantage that the lens rests against the process connection, in particular all the way around, and thus good overpressure resistance of the lens can be achieved.

[0039] The arrangement according to the invention with a positive connection also ensures that the lens is not lost when disassembling the radar level gauge. This is particularly advantageous for lenses arranged between the process connection and the process environment receptacle. Such an arrangement is also advantageous because it can reduce the number of transitions that need to be sealed.

[0040] It should be noted at this point that a lens according to the present application refers not only to dielectric components that direct electromagnetic radiation in free-radiating radar measuring devices, but also to dielectric components that serve, for example, to couple the electromagnetic radiation to a probe, e.g., a rod or a cable, and / or to insulate the probe. These components are also dielectrically active and influence the electromagnetic radiation emitted by the radar measuring device and are therefore also considered lenses in the context of the present application.

[0041] In one variant of the radar level gauge, the positive connection is designed as a snap-in connection. A snap-in connection enables a simple and cost-effective provision of a positive connection and is also easy to produce with minimal effort. A snap-in connection can be easily designed so that it can be manufactured without tools or with simple tools, meaning that no tools are required, in particular for inserting the lens and establishing the positive connection. If a press is used for assembly, for example, this ensures that the lens is pressed in centrally and without tilting.

[0042] In this context, a locking connection is understood to mean a connection in which a first component and a second component are mechanically connected in a connection direction by a locking element being positioned behind an undercut or a support of one or both components in the connection direction. By engaging behind the undercut with the locking element, movement in the connection direction is prevented once the locking element rests against the undercut.

[0043] Locking elements can be, for example, locking lugs or rings, which can be positioned behind the undercut in the connection direction by means of a movable bearing and then move behind the undercut, for example, by means of an articulated or spring-loaded bearing. Preferably, the connection direction is parallel to the main radiation direction H of the radar measuring device, and the undercut is a section that runs in the radial direction, e.g., a step or a web.

[0044] A positive fit can also be achieved using a ring spring, a double thread, a right-hand thread for the snap-on lens, and a left-hand thread for the antenna. In another variant, the positive fit can be achieved using a slotted guide, lateral insertion of the lenses into the process connection with radial locking, or similar.

[0045] In one variant, the positive connection is designed as a snap connection. Snap connections are functional elements for the simple, detachable and permanent, positive joining of components. One part deforms elastically and then interlocks, either detachably or permanently, with the other part. Snap connections can be realized, for example, using snap hooks. In snap connections, the elasticity of one of the materials used, usually plastics or spring steel, is used to connect two components. In one variant, the snap connection is implemented as a ring snap connection ("snap cylinder").

[0046] The snap connection can, for example, be designed as a ring snap connection, in which a continuous snap ring is used. A ring snap connection can be particularly advantageous because it is rotationally symmetrical, allowing the entire lens to be manufactured as a turned part. The snap ring, at the end of which a circumferential web acts as a snap element – which resembles a snap hook in a longitudinal section – can in this case be turned together with the entire lens in a production machine.

[0047] This can be particularly advantageous for lens materials that cannot be manufactured using injection molding or are difficult to manufacture. Furthermore, low production volumes may be a reason to use a turned part instead of injection molding. A material typically used for hygienic applications is polyetheretherketone (PEEK). PEEK is a high-temperature, chemically, and abrasion-resistant thermoplastic that is well suited as a lens material.

[0048] The ring snap connection can thus have, on the one hand, a preferably circumferential web with locking elements or the locking element and, on the other hand, a preferably circumferential support as an abutment.

[0049] Preferably, the ridge is located on the lens side and the support on the process connection side. This arrangement has proven particularly advantageous, as it allows the flexibility of the lens material to be utilized to create a spring effect. The process connection with the support, which acts as a counterbearing, can then be made of stainless steel, for example.

[0050] The ring and / or the support can be segmented in the circumferential direction. This can be used, for example, to increase the flexibility of the spring element and facilitate assembly of the components. A segmented design of the snap ring reduces compression in the circumferential direction when inserting the snap ring, thus simplifying insertion.

[0051] Individual locking hooks, preferably evenly distributed around the circumference of the lens, can be made shorter and with a greater material thickness than a snap ring, so that they are also more stable.

[0052] In one embodiment, a lens-side part of the positive connection is molded from the same material as the lens. This has the advantage that the lens and the lens-side part of the positive connection can be manufactured in a single operation. For example, the lens with the lens-side part of the positive connection arranged on it can be manufactured in a single injection molding process as an injection-molded part or in a turning process as a turned part. Combinations of the various processes are also possible and can be used.

[0053] In an alternative embodiment, the lens can be formed in at least two parts, consisting of a lens body and a connecting part, whereby the connecting part, as the lens-side part of the positive connection, can then be formed from a different material than the lens body. Such a design has the advantage that, for example, the lens is made of a dielectric plastic adapted to hygienic requirements, e.g., PEEK, and the connecting part is made of a plastic adapted to the mechanical requirements of the attachment and, if necessary, is easy to process.

[0054] This means that, for example, stable and dielectrically adapted lenses can be manufactured by combining a PEEK lens body with a stable and injection-moldable plastic.

[0055] The lens body and the connecting part can be manufactured separately and joined together using a suitable joining technique. For example, a connection can be made by adhesive bonding, ultrasonic welding, or laser welding. Alternatively, screw connections, face screw connections, other snap connections, and press fits are also possible.

[0056] Such a two-part lens can be manufactured particularly easily using a two-component injection molding process. In such a two-component injection molding process, the lens body, for example, is prefabricated from a first material, such as PEEK, and inserted into an injection mold. The connecting part can then be molded onto the lens body or partially overmolded, creating a bonded connection between the two parts.

[0057] In one variant, an insert is arranged in the process connection, which is preferably integrally formed with an antenna, preferably a horn antenna. The advantages of a horn antenna have already been explained in detail above. However, the insert can also be configured with a different antenna, e.g., a planar antenna. The planar antenna can be designed, for example, as a so-called phased array antenna, with an adjustable main radiation direction H. Antennas with an adjustable main radiation direction H can be used in particular in topology-detecting radar measuring devices.

[0058] The variant with an insert that preferably forms or accommodates the antenna achieves a structure in which the process connection can be particularly well adapted to the requirements of the process environment.

[0059] The insert can then be made of a material adapted to the local requirements.

[0060] In one embodiment, the insert is designed as a driver for preloading the lens relative to the process connection. For this purpose, the insert can, for example, be screwed into the process connection. The insert itself can have a thread by means of which it is screwed into the process connection, which then has a corresponding thread. Alternatively, a driver with a thread can be screwed into the process connection, thus pressing the insert into the process connection.

[0061] In one variant, the insert is arranged and designed in such a way that, when inserted into the process connection, it blocks the positive connection from coming loose. Preferably, the insert is dimensioned such that mechanical blocking prevents the locking elements, such as the locking lugs, from coming loose. This ensures that the connection between the lens and the process connection cannot be accidentally released when the field device is mounted.

[0062] The insert can further comprise a stop, preferably a circumferential stop, to limit the insertion depth of the stop into the process connection. Such a stop prevents the lens from being pushed out of the process connection by inserting the stop, and prevents the positive connection from being destroyed by inserting the insert too deeply.

[0063] In one variant, the positive connection is designed as a snap ring arranged between the process connection and the lens. Such a snap ring can simply be mounted in two corresponding grooves. When installed, the snap ring overlaps both grooves in the radial direction, thus achieving a positive connection in the connection direction. For insertion, the snap ring can be arranged in one of the grooves and expanded or compressed (squashed) by suitable guide edges on the other component.

[0064] The grooves required for this purpose can be produced particularly easily through a turning process for a rotationally symmetrical component. The process connection and the lens then have grooves that correspond to each other, with the snap ring being dimensioned such that, when installed, it lies between the process connection and the lens in such a way that it limits axial movement at least in the front direction.

[0065] In a preferred embodiment, which can be achieved both with a locking or snap-in connection and when using a retaining ring as a connecting element, the lens is mounted so that it can rotate relative to the process connection. A rotatable arrangement of the lens relative to the process connection and thus also to the radar measuring device ensures that when the radar measuring device is fastened in the holder of the process environment, e.g. by screwing it in, the lens can rotate relative to the radar measuring device. A seal arranged between the lens and the holder, e.g. an O-ring, can therefore be used with no or at least reduced shear forces acting on the seal. Ideally, the lens is stationary relative to the holder when the radar measuring device is connected to the holder, so that no forces act on the seal arranged between the lens and the holder in the circumferential direction.An improved sealing effect is achieved by reducing the circumferential load on the seal.

[0066] In an alternative design, the lens is mounted in a rotationally fixed manner relative to the process connection. A rotationally fixed mount can be useful if the lens is heated, for example, by means of parallel heating wires embedded in or applied to the lens. Since the metallization can impede or even prevent the emission of an electromagnetic field, it can be crucial in these cases that the electric field oscillates perpendicular to the heating wires. Such a grating is only permeable to this polarization.

[0067] In order to achieve the best possible seal, it is advantageous if a first seal is arranged between the lens and the process connection, wherein the lens preferably forms a receiving space for the first seal. It is advantageous if the first seal is used to seal directly between the lens and the process connection. By consistently reducing the number of gaps and material transitions that need to be sealed, improved tightness and a reduction in gaps in which contamination can accumulate can be achieved. The lens preferably forms a first receiving space for the seal, which can preferably be designed as being formed in the lens. The first seal is therefore arranged radially between the lens and the process connection and prevents medium from penetrating into a space between the process connection and the lens.

[0068] Preferably, the lens is designed so that it is positioned at least partially in front of the process connection in the main radiation direction. This ensures that only a gap between the lens and the process environment receptacle needs to be sealed against the process environment. Advantageously, a receiving space for the seal is formed and delimited by the lens and the receptacle.

[0069] A measuring arrangement according to the invention comprising a radar measuring device, in particular a radar level measuring device and a receptacle, in which the radar measuring device has a housing and can be sealingly connected to the receptacle, is characterized in that the radar measuring device is designed according to the above description.

[0070] It is particularly advantageous if a second seal is arranged directly between the lens and the receptacle, preferably meeting the requirements of hygienic processes. This means, in particular, that the seal is free of dead space and easy to clean.

[0071] A particularly good seal of the transition between the installed radar measuring device and an adjacent inner wall of the holder, e.g. of the container or adapter, is achieved by pressing a part of the second seal into a lateral spacing area located between them, which results from the lens having a diameter in the area of a through opening formed by the holder that is smaller than a diameter of the through opening.

[0072] For deforming purposes, the second seal is pressed in the direction of the container interior by a driver on the radar measuring device when the radar measuring device is inserted, whereby a through-opening into which the radar measuring device is inserted tapers towards the container interior, thus forming an abutment for the second seal. By means of such an arrangement and corresponding assembly, a part of the second seal is pressed into the intermediate space or spacing area between the inside of the through-opening and an outer circumference of the lens. This sealing part, which is pressed into the spacing area in a deformed manner, clamps the radar measuring device within the through-opening in a lateral direction, i.e. in the direction of a plane essentially perpendicular to the installation direction of the radar measuring device, which is spanned by the holder in the installation area.In addition, the seal creates a seal that prevents any portions of the fill medium from penetrating the spacing area. This creates a substantially smooth surface from the receptacle, across the seal portions pressed into the spacing area, to an inner surface, i.e. in this case the surface of the lens of the radar measuring device facing the process. In this case, the inner surface of the radar measuring device is designed, for example, as an antenna cone of a radar level measuring device. In addition to preventing any fill medium from penetrating gaps, cracks, or the like, or even the inner area of the radar measuring device itself, this type of arrangement also makes cleaning easier. It should also be emphasized that this arrangement enables particularly stable clamping of the radar measuring device within the through-opening of the container.

[0073] The radar measuring device has a driver for the second seal, which presses it into the space between the lens and the holder. The driver can be designed, for example, as an integral component of the lens (made of PTFE or PEEK, for example), as the actual end face of the process connection, as the end face of the insert, or as a separating or transition element to the lens. The driver, the peripheral wall of the lens located in front of it, as well as an inner wall of the through-opening of the holder and a wall section of the opening wall projecting into the through-opening form a space for accommodating the second seal.

[0074] By arranging the seal directly between the lens and the holder, ie in particular the container or adapter, without any intermediate components, the reduction of the gap to be sealed enables a particularly tight design and thus the use in hygienic applications, ie in particular applications which are characterized by the design of devices and systems for easy cleaning in order to avoid contamination of food.

[0075] Ideally, the process connection should have a depth stop to limit the insertion depth of the radar level gauge into the receptacle. This depth stop allows a specified insertion depth of the radar level gauge into the receptacle to be precisely maintained, thus specifying the desired compression of the second seal.

[0076] In one embodiment, the process connection, with its front side facing the process, acts as a driver for the lens, which in turn acts as a driver for the second seal. The lens has a circumferential rib that serves as a contact surface for the process connection on the rear side and presses the second seal into the clearance area on the front side.

[0077] A lens according to the invention for a radar measuring device, in particular a radar level measuring device, has a lens body and a connecting part, wherein the connecting part is designed to form a positive connection between the lens and the radar measuring device.

[0078] The features of the lens already mentioned above with regard to its connection to the process connection of the radar measuring device also apply to the lens in isolation. In particular, a lens-side part of the positive connection can be designed as part of a locking connection, in particular a snap connection. The lens body and connecting part can in particular be formed integrally and / or from the same material. Alternatively, the connecting part can be formed from a different material than the lens body. In particular, the lens body can be formed from a dielectrically adapted, preferably temperature-resistant, and more preferably chemically and / or mechanically resistant material.

[0079] The present invention will be explained in detail below using exemplary embodiments with reference to the accompanying figures. They show: Figure 1 shows a measuring arrangement comprising a radar measuring device 1 and a recording 5 according to the prior art (already discussed), Figure 2a shows a first embodiment of a measuring arrangement comprising a radar measuring device 1 and a recording 5, Figure 2b shows an enlargement of a first section of Figure 2a , Figure 2c an enlargement of a second section of Figure 2a , Figure 3a a second embodiment of a measuring arrangement with a radar measuring device 1 and a recording 5, Figure 3b an enlargement of a section of Figure 3a and Figure 4 shows an alternative embodiment of the lens 16.

[0080] In the figures, unless otherwise stated, the same reference symbols designate the same or corresponding components with the same function.

[0081] Figure 2ashows a first exemplary embodiment of a measuring arrangement with a radar measuring device 1 and a receptacle 5, which in the present case is designed as a clamp adapter. The radar measuring device 1 is designed in the present exemplary embodiment as a radar level measuring device 1 and extends from a rear housing 3a via a process connection 3 formed with a screw-in thread to a lens 16 arranged on the front, i.e. oriented towards a process environment I. The lens 16 is seated in the receptacle 5 and is prestressed by the process connection 3 in the direction of the process environment I. The lens 16 is connected circumferentially to the process connection 3 via a positive connection 20, wherein the detailed design of the positive connection 20 is shown in the Figure 2b shown in the enlarged detail Y.

[0082] The lens 16 is made of a dielectric material that is particularly suitable for hygienic applications. One suitable material for this purpose is, for example, polyetheretherketone (PEEK), which, as a semi-crystalline thermoplastic, has very good mechanical and thermal properties. The lens 16 is designed with a diameter such that a circumferential annular gap exists between an outer circumference of the lens 16 and an inner wall of the receptacle 5, in this case the adapter, so that a spacing region 14 is formed between the receptacle 5 and the lens 16. A second seal 10, which is arranged between the lens 16 and the receptacle 5 and is designed as a commercially available O-ring in this case, is pressed into the spacing region 14 by a driver 13 molded onto the lens 16.In the present embodiment, a front face of the process connection 3 acts on the driver 13, thus preloading the lens 16 toward the process environment. In the present embodiment, the process connection 3 is screwed into the adapter 5 via a screw thread, with the screw-in depth being limited by a depth stop 35 located on the rear side of the adapter 5. This depth stop 35 prevents the lens 16 from being pushed out of the adapter 5 in the front direction. The position of the lens 16 relative to the receptacle 5 can thus be determined in advance.

[0083] Between the lens 16 and the process connection 3, in an area in which the lens 16 is arranged within the process connection 3, there is arranged a circumferential first seal 11, which is arranged in a groove 12 in the lens 16. This first seal 11 prevents the penetration of medium into the interior of the radar measuring device 1 and clamps the lens 16 in the process connection 3. In order to prevent the lens 16 from falling out of the process connection 3 during assembly and disassembly, it is held in the process connection 3 via the positive connection 20, which in the present embodiment is designed as a ring snap connection. Loosening of the ring snap connection is prevented by an insert 31 arranged in the process connection 3. The insert 31 is designed and arranged such that it prevents loosening of the ring snap connection by preventing the locking elements from springing open.In the present embodiment, the insert 31 is formed integrally with an antenna horn 52 of a horn antenna 50 for emitting the radar radiation of the radar measuring device 1. The horn antenna 50 is filled with a filling 54 made of a dielectric material.

[0084] Figure 2b shows an enlarged detail of the positive connection 20 from Figure 2a. In the illustrated section, it can be seen that a locking element 22 is formed in a circumferential area on the lens 16 for a spring bar 23. The spring bar extends rearward in the axial direction and enables the lens 16 to be inserted from the front into the process connection 3 of the radar level measuring device 1. Corresponding starting edges on the locking element 22 on the one hand and on a web 24 of the process connection 3 designed as a support 24 on the other hand enable the locking element 22 to lie behind the web 24 and thus prevent any movement of the lens 16 in the axial direction in the front direction.To prevent the locking connection between the lens 16 and the process connection 3 from becoming loose, the insert 31 is dimensioned such that, when mounted, it lies directly behind the spring bar 23 of the locking connection, thus preventing the spring bar 23 from springing back and the locking element 22 from moving beyond the bar 24. At the same time, the lens 16 is preloaded in the front direction by the insert 31, so that movement in the rear direction is also prevented in this state.

[0085] Figure 2c shows an enlarged detail of detail Z from Figure 2a .

[0086] In this enlarged detail, it can be seen particularly clearly that the lens 16 has a circumferential web 24 extending in the radial direction, which acts as a driver 13 for the second seal 10. The driver 13 is in direct contact with an end face of the process connection 3 in the rear direction, which preloads the lens 16 in the installed state towards the process environment I. The driver 13 presses the second seal 10 into the spacing area 14 between the receptacle 5 and the lens 16 in a beam-shaping manner and protrudes slightly from this spacing area 14 towards the process environment. The direct seal between the lens 16 and the receptacle 5 preloads the lens 16 in the receptacle 5, thus ensuring a particularly stable and tight arrangement.The first seal 11 between the lens 16 and the process connection 3 sits in a circumferential groove 12 which forms a receiving space 12 for the first seal 11. The positive connection 20 between the lens 16 and the process connection 3 prevents movement of the lens 16 in the axial direction, but rotation of the lens 16 about a longitudinal axis A of the radar measuring device is still permitted. In this way, when the radar measuring device 1 is inserted into the receptacle 5, the lens 16 together with the second seal 10 remains stationary relative to the receptacle 5 or at least rotates less than would be the case with a rotationally fixed connection between the lens 16 and the process connection 3. In this way, shearing of the second seal 10 in the circumferential direction is reduced, thus achieving an improved seal between the lens 16 and the receptacle 5.

[0087] Figure 3ashows a second embodiment of a measuring arrangement in a radar measuring device 1 and a receptacle 5, wherein the positive connection 20 between the lens 16 and the process connection 3 is achieved by a snap ring 26 arranged in mutually corresponding grooves 20 of the lens 16 and the process connection 3. The further construction of the Figure 3a The embodiment shown does not differ from the structure of the measuring arrangement according to Figure 2a , so reference is made to the comments therein.

[0088] An enlarged detail of the positive connection 20 between the lens 16 and the process connection 3 is shown in Figure 3b , which is an enlarged detail of the detail Z from Figure 3a shows, shown.

[0089] In the enlarged section of the Figure 3bIt can be clearly seen that the snap ring 26 is arranged in a groove 12 of the lens 16, wherein the front section of the process connection 3 has a leading edge such that the snap ring 26 is compressed when the lens 16 is inserted into the process connection 3, is pushed completely into the groove 12 of the lens 16 and then expands again after it has slid over a locking lug 37 formed at the front end of the process connection 3. In addition to the locking lug 37 in the manner already described, the lens 16 forms a driver 13 for the second seal 10, formed by a circumferential web, so that the latter is pressed by means of the driver 13 in the front direction into the spacing area 14 between the receptacle 5 and the lens 16.

[0090] Figure 4 shows an alternative embodiment of the lens 16, wherein the lens shown in Figure 4The embodiment shown is formed from a lens body 15 with a molded-on driver 13 and receiving space 12 for the second seal 10, and a connecting part 17 is molded onto the rear of the lens body 15, by means of which the positive connection 20 between the lens 16 and the process connection 3 is made possible. The connecting part 17 can, for example, be moved onto the lens body 15 using a two-component injection molding process. In this way, it is possible for the lens 16 to be manufactured from a material other than an injection molding process and to be connected to the connecting part 17. In this way, it is also possible to combine a comparatively brittle material, which is not suitable for forming a spring tongue for the positive connection 20, with a suitable elastic material, so that the advantages of different materials can be combined in this way.

[0091] A key feature of this measuring arrangement is that a plastic lens is snapped onto the outside of the process connection 3. An O-ring is inserted into a receiving space 12 defined on the inside and back by the lens 16. This O-ring then seals directly against the receptacle 5, forming a seal approved for hygienic applications. This process connection 3 can be designed in different ways, thus enabling various connections.

[0092] The lens 16 is held in the process connection 3 of the radar measuring device 1 via a positive connection 20, in particular a snap hook or a retaining ring, even when the radar measuring device 1 is disassembled. The lens 16 is thus preferably rotatably held in the process connection 3 and thus does not rotate when screwed into the receptacle 5. As a result, a seal between the lens 16 and the receptacle 5, e.g., an O-ring, is not excessively deformed / damaged during assembly, and the sealing function is not impaired.

[0093] The fastening of the lens 16 by means of a form fit is preferably carried out by means of a snap hook, which is advantageously designed as a rotationally symmetrical turned part for cost-effective production and means that no further fastening materials are required for the lens 16. Reference symbol list

[0094] 1Radar measuring device, radar level measuring device 2Vessel 3Process connection 4Through opening 5Receptacle, flange, adapter 6Threaded hole 7Clamping screw 8Carrier 9Clamping clamp 10Second seal 11First seal 12Receiving space, groove 13Drive member 14Spacing area 15Lens body 16Lens 17Connecting part 18Opening wall 20Form-locking connection 22Locking element 23Spring bar 24Support, bar 26Retaining ring 31Insert 33Stop 35Depth stop 37Locking lug 50Horn antenna 52Antenna horn 54Filling 1aRadar electronics 2aContainer interior 3aHousing HMain radiation direction IProcess environment

Claims

1. Radar measuring device (1), in particular radar level measuring device, with a housing, wherein the housing (3a) can be connected in a sealing manner to an accommodating portion (5), wherein the housing (3a) is configured at the front as a process connection (3) and wherein a dielectric lens (16) is disposed at the front of the housing (3a) and connected to the process connection (3) such that the lens (16) is fixed in the axial direction relative to the housing (3a), wherein a positive connection (20) is formed between the lens (16) and the process connection (3), characterized in that a) the positive connection (20) is configured as a latching connection and / or as a snap-fit connection and an insert (31) is arranged in the process connection (3) in such a way that it blocks release of the positive connection, the insert (31) ensuring that the connection between the lens (16) and the process connection (3) cannot be inadvertently released and / or b) the positive connection (20) is configured as a ring snap connection and the ring snap connection has, on the one hand, a web (23) with latching members (22) and, on the other hand, a contact portion (24) as an abutment and / or c) the positive connection (20) is formed by a snap ring (26) arranged between the process connection (3) and the lens (16).

2. Radar measuring device (1) according to claim 1, wherein the positive connection (20) is configured as a ring snap connection and the ring snap connection has, on the one hand, a web (23) with latching members (22) and, on the other hand, a contact portion (24) as an abutment characterized in that the web (23) is formed on the lens side and the contact portion (24) is formed on the process connection (3) side.

3. Radar measuring device (1) according to claim 1, wherein the positive connection (20) is configured as a ring snap connection and the ring snap connection has, on the one hand, a web (23) with latching members (22) and, on the other hand, a contact portion (24) as an abutment characterized in that the ring and / or the contact portion (24) is segmented in the circumferential direction.

4. Radar measuring device (1) according to one of the preceding claims, characterized in that a lens-side part of the positive-locking connection is formed from the same material as the lens (16).

5. Radar measuring device (1) according to one of claims 1 to 3, characterized in that the lens (16) is formed in at least two parts from a lens body (15) and a connecting part (17), the connecting part (17) being formed as the lens-side part of the positive-locking connection from a different material than the lens body (15).

6. Radar measuring device (1) according to claim 5, characterized in that the lens body (15) and the connecting part (17) are connected to one another by means of two-component injection molding.

7. Radar measuring device (1) according to one of the preceding claims, wherein the positive connection (20) is configured as a latching connection and / or as a snap-fit connection and an insert (31) is arranged in the process connection (3) in such a way that it blocks a release of the positive connection characterized in that the insert (31) is configured as a driver for pretensioning the lens (16) relative to the process connection (3).

8. Radar measuring device (1) according to one of the preceding claims, wherein the positive connection (20) is configured as a latching connection and / or as a snap-fit connection and an insert (31) is arranged in the process connection (3) in such a way that it blocks a release of the positive connection, characterized in that the insert (31) is integrally formed with an antenna, preferably a horn antenna (50).

9. Radar measuring device (1) according to one of the preceding claims, wherein the positive connection (20) is configured as a latching connection and / or as a snap-fit connection and an insert (31) is arranged in the process connection (3) in such a way that it blocks a release of the positive connection, characterized in that the insert (31) has a stop (33), preferably a circumferential stop (33) for limiting an insertion depth of the stop (33) into the process connection (3).

10. Radar measuring device (1) according to one of the preceding claims, wherein the positive connection (20) is formed by a snap ring (26) arranged between the process connection (3) and the lens (16), characterized in that the process connection (3) and the lens (16) have grooves which correspond to one another and the snap ring (26) is dimensioned in such a way that, in the assembled state, it comes to lie between the process connection (3) and the lens (16) in such a way that it limits an axial movement at least in the front direction.

11. Radar measuring device (1) according to one of the preceding claims, characterized in that the lens (16) is rotatably mounted relative to the process connection (3).

12. A radar measuring device (1) according to any one of claims 1 to 10, characterized in that the lens (16) is mounted in a rotationally fixed manner relative to the process connection (3).

13. Radar measuring device (1) according to one of the preceding claims, characterized in that a first seal (11) is disposed between the lens (16) and the process connection (3), the lens (16) preferably forming a receiving space (12) for the first seal (11).

14. Measuring arrangement comprising a radar measuring device (1), in particular a radar level measuring device, and an accommodating portion (5), wherein the radar measuring device (1) has a housing (3a) and can be connected to the accommodating portion (5) in a sealing manner, characterized in that the radar measuring device (1) is designed in accordance with one of the preceding claims.

15. Measuring arrangement according to claim 14, characterized in that a second seal (10), which preferably meets the requirements of hygienic processes, is arranged directly between the lens (16) and the accommodating portion (5).

16. Lens (16) for a radar measuring device (1), the lens having a lens body (15) and a connecting part (17), the connecting part (17) being suitably configured to form a positive connection between the lens (16) and the radar measuring device (1), characterized in that the radar device (1) is configured according to one of the preceding claims.

17. Lens (16) according to claim 16, characterized in that the lens body (15) and the connecting part (17) are connected to one another by means of two-component injection molding.