Sensor unit for pipe inspection

Abstract

A sensor unit (40, 50) for pipe inspection comprises a plurality of sensors (44, 54) and a shielding is provided for the sensors (40, 50) with respect to a fluid present in the pipe. On the one hand, the shielding is formed by flow guiding elements (46) which are arranged on both sides of sensors (44) of the sensor unit (40) in the pipe tangential direction and thus span a shielding volume in which sensors (40) are located and which is also adjacent to and / or bounded by the inner wall of the pipe. And / or on the other hand that the shielding is established by at least one circumferentially closed channel, such as in particular a hose (56) or a tube, which extends over the length of the sensors (54) in the longitudinal direction of the sensor unit (50).

Description

240026 1Sensor unit for pipe inspection

[0001] The present invention relates to a sensor unit for pipe inspection, a pipe inspection device and a corresponding method.

[0002] Pipe inspection devices are known from prior art, which are set up to take measurements in the pipe during ongoing conveying operation. EP 0 955 103 A1 shows a such a device with a bypass for speed control. As part of the invention, the problem was recognized that a bypass fluid flow along the sensors can have a negative effect on the measurement results. This problem occurs especially when the inspection device is a multi-part device, i.e. with a guide unit and a upstream sensor unit. Thus, the problem to be solved is to achieve improvements to the quality of the measurement results.

[0003] This problem is solved by providing a shielding for the sensors from the bypass fluid flow. Accordingly, a sensor unit for pipe inspection comprises a plurality of sensors and shielding is provided for the sensors against a fluid present in the pipe. This can be achieved in two ways: On the one hand, the shielding can be formed by flow guiding elements that are arranged on both sides of the sensors of the sensor unit laterally to the sensor unit, thus in the tangential direction of the pipe. This creates a shielding volume in which the sensors are located, and which is also limited by the inner wall of the pipe. The bypass flow is thus separated from this shielding volume. But at least the flow speed close to the sensors is reduced by these measures. Also, a flow is provided close to the sensors such that turbulences are widely eliminated that could harm the measurement results. On the other hand, the shielding can also be provided by at least one circumferentially closed channel which carries the bypass flow, such as in particular a hose or a tube, which extends over the length of the sensors in the longitudinal direction of the sensor unit.

[0004] It is advantageous if the distance between the flow guiding elements and the inner wall of the pipe is less than 50% of the distance between the sensors and the inner wall of the pipe. Preferably less than 30% of this dimension and particularly preferably less than 10% of this dimension. Between the flow guiding elements, as will be explained below, a flow-calmed area is created in which the sensors are located240026 2 and the smaller the distance from the flow guiding elements to the inner wall of the pipe, the more the flow is calmed or even eliminated. The mentioned “inner wall of the pipe” and in particular its diameter is a dimension that results directly from the sensor unit, namely by reference to the rollers, which will be explained below.

[0005] It is also advantageous if the distance from the sensors to the inner wall of the pipe is at least 10 mm, preferably at least 30 mm, when the pipe inspection device is used accordingly to its purpose. The sensors can be ultrasonic sensors. With some physical measuring principles, such as magnetic measurements, the smallest possible distance from the sensors to the test object is advantageous. With ultrasonic measurement, on the other hand, a greater distance can be advantageous, as these sensors have an opening cone of the measurement and a larger area can be advantageous to work in the far field of the ultrasonic sensors. In some embodiments, the distance between the sensor and the wall can be mor than 50 mm.

[0006] Furthermore, the sensor unit can comprise a coupling element or can be connected to it. This allows the sensor unit to be coupled with other sensor units or a guide unit. This coupling causes the sensor unit(s) to move at the speed of the guide unit. The coupling is a connection of those components that preferably can be opened such that elements of the chain of these units can be exchanged. This is advantageous when adapting the device to different sensing purposes.

[0007] It is also advantageous if the sensors are each arranged on a sensor carrier. The sensor carrier is also the carrier for the flow guiding element. In particular, the sensor carrier also comprises boundary elements which, together with the flow guiding elements, form a frame around these sensors. The edges pointing radially outwards are at a defined small distance from the pipe wall and this frame has constructively provided openings or apertures or slots or gaps to allow a certain amount of fluid exchange with the surrounding fluid. This mentioned small distance is preferably less than 15%, in particular less than 5% of the radially length of the flow guiding elements. These edges of both the boundary elements and flow guiding elements are preferably equidistant to pipe’s inner wall.240026 3

[0008] In addition, the sensor unit preferably does not comprise any adjustable means for setting a bypass fluid flow, which would be adjustable in particular via a control unit. The term "control unit" refers in particular to an electronic control unit. This wording makes it clear that the sensor unit is part of a multi-part pipe inspection device. The invention is in particular not related to one-part designs, such as those might have a central conduct and are thus related to a rather different design.

[0009] In addition, the sensor unit can comprise at least one sealing disk whose diameter largely corresponds to the internal pipe diameter or is slightly smaller. It also comprises at least one aperture that is connected to a bypass channel. The bypass channel is aligned in the longitudinal direction of the pipe and has at least partial fluid separation from the sensors. The term "sealing disk" is to be understood broadly and includes all structures that have an outer area that is adapted to the inner diameter of the pipe and comprises a largely closed cross-sectional area. The separation is formed in particular by the aforementioned flow guiding elements or the circumferentially closed channel. This channel, which can be in particular a hose, is preferably fixed (or mounted to ) at least one of the sealing disks. The sealing disk(s) is / are therefore aligned transversely to the longitudinal direction of the pipe.

[0010] Furthermore, in addition to the means described above for enabling a bypass fluid flow, the sealing disk can also comprise means for reducing the sealing effect. These means comprise either at least one bore that is not connected to a bypass channel. And / or the outer diameter of the sealing disk is structurally provided with a radial clearance to the inner pipe wall. And / or the design or the material of the sealing disk is such that there is no optimized sealing effect with respect to the inner wall of the pipe and thus during operation there is a leakage of at least 1 %, preferably at least 5%, of the fluid flow. Conventionally, it is usual for a seal to be designed to achieve a good sealing function. However, here the peculiarity of the described features is that a certain proportion of the bypass volume flow does not take place via the bypass means provided by the design, but along an area of the sensor unit which is in direct fluid connection with the sensors and this enables this area to be flushed, which would be associated with a reduction in the quality of the sensor measurement results if the area were to become contaminated. In other words, the sealing disk comprises a plurality of apertures, each of which is connected to the bypass channel and each of which has at least partial fluid separation from the sensors. This embodiment with only one240026 4 bypass channel is particularly advantageous if the sensor unit comprises a radially inner and coaxially aligned bypass channel. In some embodiments, however, an additional functional unit of a certain size is necessary in the sensor unit (e.g. for electronics), which requires a certain part or a large part of the space in the center of the sensor unit. In particular, this at least aperture is not coaxial. Using the mentioned hoses is advantageous because they can be winding around structural elements of the sensor unit.

[0011] Preferably, the sensor unit comprises a plurality of sensor carriers, each with a large number of sensors, and the sensor carriers are radially movable via guide elements. This ensures that the intended distance from the sensors to the inner pipe wall is achieved even if the inner pipe diameter varies.

[0012] A pipe inspection device with a multi-part structure comprises a guide unit and at least one coupled sensor unit. The guide unit comprises a seal with respect to the pipe and is set up to allow a bypass fluid flow through the guide unit that can be varied by a control system. Coupling comprises in particular that both units are separate mechanical assemblies which are connected to a coupling element which in particular defines the distance between these units.

[0013] In a method for pipe inspection, a sensor unit does not include means for changing its fluidic resistance to the flow within a pipe to be inspected. A sensor carrier includes at least one sensor and the sensor unit includes shielding elements, to create a fluidically calmed area in a space between the sensors and the inner wall of the pipe.

[0014] The invention is described below in preferred embodiments. The figures show: Fig. 1 a side view of a pipe inspection device,Fig. 2 a side view of a guide unit of the pipe inspection device,Fig. 3 a perspective view of a sensor unit,Fig. 4 a detail of the embodiment according to Fig. 3 andFig. 5 an alternative embodiment of a sensor unit.

[0015] Fig. 1 shows a pipe inspection device 10, which comprises a guide unit 20 and preferably a plurality of sensor units 40. In particular, at least one sensor unit 40 is240026 5 used. The sensor unit 40 is designed as a unit that is separate from the guide unit 20 and is connected to the guide unit via a coupling element 30. In Fig. 1 , the coupling element 30 is designed as a cardan element. Preferably, the coupling is such that the sensor unit 40 can be positioned or aligned in the pipe’s radial direction independently of the guide unit 20. The degrees of freedom are thus (as with a gimbal element) the pivotability in the axes within the pipe cross-section. Preferably, there can be no degree of freedom of rotation in the longitudinal direction of the tube. The latter is advantageous if several sensor units 40 are used and the pipe measurement is to be optimized via a required alignment of the sensors of different sensor units to each other.

[0016] The guide unit 20 comprises at least one sealing ring 22 in order to achieve a good sealing with respect to the pipe 5. (see fig. 5) Preferably, the pipe inspection device 10 inspects the pipe 5 during operation, which means with a fluid flow. So that the pipe inspection device 10 does not move at the same speed as the volume flow of the conveyed medium, the pipe inspection device 10 permits a bypass volume flow 29. The bypass volume flow 60 defines of how much the speed of movement of the pipe inspection device 10 is lower than the said volume flow. A defined speed of movement is essential for a good inspection of the pipe. For this purpose, the guide unit 20 comprises flaps (or in general: valves) that can be regulated by a control system in such a way that the pipe inspection device 10 moves in the pipe at the desired speed. In addition, brakes and driven wheels / rollers can preferably be provided on the guide unit in order to achieve a better control the speed. The guide unit 20 can also comprise its own sensor(s) 24, which is / are also used in particular to check and determine the speed.

[0017] Particularly due to space problems and the need for a large number of sensors for different measurement tasks, all needed sensors can often not be integrated in said guide unit, but a separate sensor unit 40 is coupled to the guide unit 20. The sensor unit(s) 40 do not comprise components for motion control, but are focused or limited for their measuring task(s). They might be designed to have a low flow resistance, as the bypass volume flow 60 must flow through them.240026 6

[0018] The volume between the sensors and the inner wall of the pipe is filled with the fluid that is transported in the pipe. It has been recognized that turbulence might occur, which can have a harmful effect on the measurement results. The design concept described below reduce these harmful effects.

[0019] Fig. 3 shows the sensor unit 40. Starting from a base body 41 , several sensor carriers 42 are shown, each comprising a plurality of sensors 44. The sensors are in principle aligned in the longitudinal direction of the sensor unit 40. In particular they can be arranged in two rows as shown. Further they may have a certain degree of inclination so that the inner wall of the tube can be scanned by all the sensors at all circumferential locations, when the sensor unit 40 is moved axially. Flow guiding elements 46 are arranged on the outer areas of the sensor carriers 42. They have an orientation in the longitudinal direction of the sensor carrier and are directed radially outwards. This structure can be seen in detail in Fig. 4. Two bearing arms 43 are pivotably mounted on the base body 41 , which are pivotably mounted on the sensor carrier 42. In some embodiments, this design can be considered as a four-link coupling element. The sensor carrier 42 is pressed outwards by means not shown, such as springs in particular, so that rollers 45, which are also mounted on the sensor carrier 42, are pressed against the inner wall of the tube. This creates a defined distance between the sensors 44 and the pipe’s wall. Also, a defined distance from the flow guiding elements 46 to the inner wall of the pipe is achieved. As described above, fluid flows through the sensor unit 40. The flow guide elements 46 are used to rectify the bypass fluid flow 60 in the longitudinal direction of the pipe, thus reducing turbulence along the sensors. Also the flow volume along the sensors 44 can be reduced. In addition, limiting elements 47 are preferably arranged upstream and downstream of the sensors 44. They also reduce the flow from the transported fluid along the sensors 44. The flow guide elements 46 and the limiting elements 47 thus jointly create a frame or box in which the sensors 44 are located and which is open in the direction of the inner pipe wall. This reduces significantly the flow of the transported fluid into the inside the box. Thus, a harmful influence of that flow to the measurement results is excluded. However, it could be negative if that box might be tightly sealed, as contaminants might not be drained off properly and could accumulate in it. For this reason, this box is designed with openings to the rest of the sensor unit. These are preferably provided by slots 48 within the limiting element 47 and or guiding elements 46. These openings240026 7 can also be realized by shortening the length of these elements 46, 47 in their radially outward direction, so that they are at a distance from the inner wall of the tube.

[0020] Fig. 5 shows an alternative embodiment of the sensor unit 50 which is located in a section of a tube 5. It also comprises sensors 54, which are schematically sketched here as an area. A plate 52 is provided at both axial ends, whereby, according to the invention, just one of these plates might be sufficient, regardless of the side where it is positioned. These plates 52 have openings 54 to which hoses 56 are coupled, so that the required bypass fluid flow 60 is directed through the hoses 56 and is thus separated from the sensors 54. For this reason, flow guiding elements 46 and limiting elements 47 are not necessary for this embodiment. An extension 56' of a hose is also shown which can be used to establish a connection to the next sensor unit 50 (not shown). Since the hoses have certain mechanical strength and are not compressible in their longitudinal direction, they can be used to support the above-described coupling of two sensor units or with the guide unit 10. They might even substitute a mechanical coupling element.

[0021] The plates 52 are preferably designed to seal against the inner wall of the pipe, but could preferably also be provided with a clearance fit so that no perfect sealing effect is created. In this way, the limited fluid exchange, which is advantageous for cleaning purposes, can be realized. Alternatively, or additionally, passages or holes 59 can be provided in the plates, which are not connected to a hose and thus enable fluid exchange in the area in between.

[0022] Combinations of the embodiments of Figures 3 or 5 are considered to be included in the scope of protection, such that that, for example, a hose can be used as a bypass element in the embodiment of Fig. 3. Or a fluid shielding of the sensors 54 of Fig. 5 can be provided, according to the respective other embodiment.240026 8[00231 Reference numerals:10 pipe inspection device20 guide unit22 seal24 sensors29 bypass volume flow30 coupling element40,50 sensor unit41 base body42 sensor carrier44 sensors45 rolls46 flow guiding elements47 boundary element48 slot50 sealing disc52 plate54 opening56, 56‘ shielding element, in particular as a bypass channel, or hose59 passage or hole60 bypass fluid flow

Claims

240026 9Claims:1 . Sensor unit (40, 50) for pipe inspection, characterized in that the sensor unit (40, 50) comprises at least one sensor and preferably a plurality of sensors (44, 54) and a shielding is provided for the sensors (40, 50) with respect to a fluid present in the pipe, wherein on the one hand, the shielding is formed by flow guiding elements (46) which are arranged on both sides of sensors (44) of the sensor unit (40) in the pipe tangential direction and thus span a shielding volume in which sensors (40) are located and which is also adjacent to and / or bounded by the inner wall of the pipe, and / or on the other hand that the shielding is effected by at least one circumferentially closed channel, such as in particular a hose (56) or a tube, which extends over the length of the sensors (54) in the longitudinal direction of the sensor unit (50).

2. Sensor unit (40) according to claim 1 , wherein the distance of the flow guiding elements (46) to the inner pipe wall is less than 50% of the distance from the sensors to the inner pipe wall, preferably less than 30% of this dimension and particularly preferably less than 10% of this dimension.

3. Sensor unit (40, 50) according to claim 1 or 2, characterized in that the distance from the sensors (40) to the inner wall of the pipe is at least 10 mm, preferably at least 30 mm, when the pipe inspection device is used accordingly, and / or in that the sensors (44, 54) are ultrasonic sensors.

4. Sensor unit (40, 50) according to one of the preceding claims, characterized in that the sensor unit (40, 50) comprises or can be connected to a coupling element (30), via which the sensor unit (40, 50) can be coupled to other sensor units (40, 50) and / or to a guide unit (20).240026 105. Sensor unit (40) according to one of the preceding claims, characterized in that sensors (44) are arranged on a sensor carrier (42) and the sensor carrier (42) is also the carrier for the flow guiding element (46) and in particular, the sensor carrier (42) also comprises boundary elements (47) which, together with the flow guiding elements (46), form a frame around these sensors (44).

6. Sensor unit (40) according to claim 5, wherein the flow guiding elements (46) and in particular also the boundary elements (47) have radially outwardly pointing edges that are adjacent to or at a defined small distance from the pipe wall and thus form a frame around the sensors (44) and this frame having constructively provided openings or apertures or slots (48) or spacings in order to permit a certain fluidal exchange with the surrounding fluid.

7. Sensor unit (40, 50) according to one of the preceding claims, characterized in that the sensor unit (40, 50) does not comprise any adjustable means for adjusting a bypass fluid flow (60), in particular which means that it could be adjustable via a controller.

8. Sensor unit (40) according to one of the preceding claims, characterized in that the sensor unit (40) comprises at least one sealing disc whose diameter largely corresponds to the internal pipe diameter or is slightly smaller and comprises at least one aperture which is connected to a bypass channel (56), the bypass channel (56) being aligned in the longitudinal direction of the pipe (5) and having at least partial fluid separation with respect to the sensors (44).

9. Sensor unit according to claim 8, wherein the sealing element (50), in addition to the above-described means (56) for enabling a bypass fluid flow (60), constructively comprises means for reducing the sealing effect, wherein these means either comprise- at least one opening which is not connected to a bypass channel, and / or- the sealing element is designed by construction or by the material in such a way that there is no optimum sealing effect relative to the inner wall of the pipe and thus has a leakage of at least 1 %, preferably at least 5%, of the bypass240026 11 fluid flow (60) during operation.

10. Sensor unit (40, 50) according to one of the preceding claims, wherein the sensor unit comprises a plurality of sensor carriers (42) each having one or a plurality of sensors (44) and the sensor carriers (42) are radially movable via guide elements (43).

11. A pipe inspection device (10) comprises a guide unit (20) and at least one coupled sensor unit (40) according to one of the preceding claims, characterized in that the guide unit (20) comprises a seal (22) with respect to the pipe’s inner wall and is set up to allow a bypass fluid flow (60) through the guide unit (20) which preferably can be varied by a control system.

12. A method for pipe inspection, wherein a sensor unit (40) comprises no means for changing its fluidic resistance in the flow within a pipe to be inspected, and a sensor carrier (42) of the sensor unit (40) contains at least one sensor (44) and shielding is achieved by shielding elements (46, 56), which create a fluid ically calmed area in a space between the sensors (44) and the inner wall of the pipe (5).

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