A variable inner diameter twin turbine flow measurement sensor

Abstract

The present invention relates to the technical field of flow detection equipment, and specifically discloses a variable inner diameter twin turbine flow measurement sensor, comprising a pipeline shell, wherein a front end guide, a fixed guide, and a rear end guide are sequentially arranged inside the pipeline shell from front to back, and the front end guide and the rear end guide are fixed to the inner wall of the pipeline shell; a standard turbine group is installed between the front end guide and the fixed guide, and a variable diameter turbine group is installed between the fixed guide and the rear end guide, and the fixed guide is fixed between the front end guide and the rear end guide through the standard turbine group and the variable diameter turbine group; a standard sensing component for detecting the rotation speed of the standard turbine group and a comparative sensing component for detecting the rotation speed of the variable diameter turbine group are also embedded on the surface of the pipeline shell. The present invention adopts a twin turbine structure, and sets a standard turbine and a variable inner diameter turbine, which realizes the measurement of multiple physical parameters, can eliminate the adverse effects of external factors, has high measurement accuracy, and realizes real-time measurement of mixed media or multiple media in different time periods.

Description

Technical Field

[0001] The invention relates to the technical field of flow detection equipment, and in particular to a variable inner diameter twin-turbine flow measurement sensor. Background Art

[0002] Turbine flowmeters generally measure the volume flow of the medium flowing through the turbine. The turbine structure is a fixed structure, and the turbine rotation angular velocity is proportional to the volume flow of the medium flowing through. Limited by its measurement principle, ordinary turbine flowmeters can only measure volume flow. Even if the number of turbines is increased, that is, dual turbines and multi-turbine flowmeters can only measure volume flow, and cannot reflect the mass flow of the medium. It needs to be compensated by other parameter sensors such as density and temperature, and the form of compensation measurement is not suitable for application scenarios of multiple media and mixed media. Summary of the invention

[0003] In view of the deficiencies in the prior art, an object of the present invention is to provide a variable inner diameter twin-turbine flow measurement sensor that can realize real-time volume flow measurement, mass flow measurement, and density measurement and can be applied to complex measurement scenarios.

[0004] In order to achieve the above-mentioned purpose, the present invention is implemented through the following technical scheme: a variable inner diameter twin-turbine flow measurement sensor, including a pipeline shell, wherein a front end guide, a fixed guide, and a rear end guide are sequentially arranged inside the pipeline shell from front to back, and the front end guide and the rear end guide are fixed to the inner wall of the pipeline shell; a standard turbine group is installed between the front end guide and the fixed guide, and a variable diameter turbine group is installed between the fixed guide and the rear end guide, and the fixed guide is fixed between the front end guide and the rear end guide through the standard turbine group and the variable diameter turbine group; a standard sensing component for detecting the rotation speed of the standard turbine group and a comparison sensing component for detecting the rotation speed of the variable diameter turbine group are also embedded on the surface of the pipeline shell.

[0005] The working principle of this technical solution is to use a variable inner diameter turbine for supplementary measurement, combined with a standard turbine signal, and after processing, it can measure volume flow, mass flow, medium density, and achieve high-precision measurement. By analyzing the output signal of the standard turbine, the volume flow is measured, and the mass flow is calculated by solving the difference in the dual turbine conversion coefficient K. The medium density is analyzed by mass flow and volume flow. The change in the inner diameter of the variable inner diameter turbine is linearly related to the pressure on the pressure-sensitive component after debugging, and this pressure is linearly related to the mass flow of the medium flowing through. The standard impeller can be used as the volume flow measurement, and the inner diameter of the variable inner diameter impeller combination is a variable variable. The change is proportional to the mass flow of the medium. Combined with the dual impeller output signal, the mass flow signal and medium density information can be output after signal analysis and processing. Combining the dual impeller signal can achieve higher measurement accuracy. It can be used for flow measurement of various media, flow measurement of mixed media, and is commonly used for large-caliber flow measurement and scenes requiring high measurement accuracy.

[0006] In order to better realize the present invention, further, the variable diameter turbine group includes a variable diameter turbine shaft with a hollow interior, a variable diameter magnetically conductive turbine blade is fixed in the middle of the variable diameter turbine shaft, and the inner wall of the variable diameter turbine shaft between adjacent variable diameter magnetically conductive turbine blades is provided with a guide groove, and a variable slider is installed in the guide groove, and each of the variable sliders is fixedly connected to a connecting rod at the rear end, and the other ends of all the connecting rods are fixed to the end of a pressure rod, and the other end of the pressure rod extends from the rear end of the variable diameter turbine shaft and is provided with a pressure plate.

[0007] In order to better implement the present invention, further, a tension rod is arranged between at least one group of the variable sliding blocks that are symmetrically arranged with each other.

[0008] In order to better realize the present invention, further, bearings are arranged at both ends of the variable diameter turbine shaft, the bearing at the front end of the variable diameter turbine shaft is embedded in the rear side of the fixed guide, and the bearing at the rear end of the variable diameter turbine shaft is embedded in the front side of the rear end guide, so that the variable diameter turbine group is rollingly fixed between the fixed guide and the rear end guide, and the pressure rod is embedded in the rear end of the variable diameter turbine shaft, and the pressure rod can slide back and forth at the rear end of the variable diameter turbine shaft, so that the connecting rod is deformed, pushing or pulling the variable slider to reciprocate in the guide groove.

[0009] In order to better realize the present invention, further, the standard turbine group includes a standard turbine shaft, a standard magnetically conductive turbine blade is fixed in the middle of the standard turbine shaft, bearings are arranged at both ends of the standard turbine shaft, the bearing at the front end of the standard turbine shaft is embedded in the rear side of the front end guide, and the bearing at the rear end of the standard turbine shaft is embedded in the front side of the fixed guide, so that the standard turbine group is rollingly fixed between the front end guide and the fixed guide.

[0010] In order to better realize the present invention, further, the standard induction component includes a packaging shell fixed to the outer wall of the pipe shell, a coil frame is encapsulated in the packaging shell, a magnet is embedded and fixed in the middle of the coil frame, a plurality of turns of enameled wire are wound and fixed on the outside of the coil frame, and a magnet is fixed in the middle, and one end of the magnet is exposed from the packaging shell and extends toward the inner side of the pipe shell.

[0011] In order to better realize the present invention, further, the structure of the standard sensing component and the comparison sensing component is the same, the position where the standard sensing component is embedded in the surface of the pipe shell matches the position of the standard turbine group, and the position where the comparison sensing component is embedded in the surface of the pipe shell matches the position of the variable diameter turbine group.

[0012] In order to better implement the present invention, further, the front end guide and the rear end guide are both fixed in the positioning groove on the inner side of the pipeline shell through a retaining ring.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] (1) Compared with ordinary turbine flowmeters, the present invention adopts a dual-turbine structure, and sets a standard turbine and a variable inner diameter turbine. The volume flow V is measured by the standard turbine, and the medium mass flow Q and density ρ are calculated by measuring the coefficient K2 of the variable inner diameter turbine, thereby realizing multi-physical parameter measurement;

[0015] (2) The working environment of the impeller in the present invention is the same, and the coefficient K1 of the standard turbine and the coefficient K2 of the variable inner diameter turbine have the same trend of change with the medium flow rate, which can eliminate external factors such as the medium and the environment that affect the accuracy, and can make the measurement accuracy of each parameter higher;

[0016] (3) The present invention can monitor the volume flow, mass flow, and medium density flowing through the pipeline in real time, and can be applied to the real-time measurement of mixed media or multiple media in different time periods, and can be used in special fields such as chemical industry, aerospace, and shipbuilding. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments with reference to the following drawings:

[0018] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention;

[0019] Figure 2 It is a schematic cross-sectional structure diagram of the variable diameter turbine group in the present invention;

[0020] Figure 3 It is a schematic diagram of an enlarged cross-sectional structure of a standard sensing component in the present invention;

[0021] Figure 4It is a schematic diagram of the changes of the variable diameter turbine group in the present invention.

[0022] Among them: 1-pipe shell, 2-front end guide, 3-fixed guide, 4-rear end guide, 5-standard turbine group, 51-standard turbine shaft, 52-standard magnetic turbine blades, 6-variable diameter turbine group, 61-variable diameter turbine shaft, 62-variable diameter magnetic turbine blades, 63-variable slider, 64-connecting rod, 65-pressure rod, 66-tension rod, 7-standard induction component, 71-packaging shell, 72-coil frame, 73-magnet, 74-enamelled wire, 8-comparison induction component, 9-bearing, 10-retaining ring. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Embodiment 1:

[0027] The main structure of this embodiment is as follows: Figure 1As shown, it includes a pipeline shell 1, and a front end guide 2, a fixed guide 3, and a rear end guide 4 are sequentially arranged inside the pipeline shell 1 from front to back, and the front end guide 2 and the rear end guide 4 are fixed to the inner wall of the pipeline shell 1; a standard turbine group 5 is installed between the front end guide 2 and the fixed guide 3, and a variable diameter turbine group 6 is installed between the fixed guide 3 and the rear end guide 4, and the fixed guide 3 is fixed between the front end guide 2 and the rear end guide 4 through the standard turbine group 5 and the variable diameter turbine group 6; the surface of the pipeline shell 1 is also embedded with a standard sensing component 7 for detecting the rotation speed of the standard turbine group 5, and a comparison sensing component 8 for detecting the rotation speed of the variable diameter turbine group 6.

[0028] The specific measurement process is that when the variable diameter turbine group 6 is not variable, the size of its turbine is the same as that of the turbine in the standard turbine group 5. After the medium enters the pipeline, it drives the two turbines to rotate, and the turbine rotation angular velocity ω is proportional to the medium volume flow V, that is, formula ①:

[0029] V=K×ω ①

[0030] The corresponding coefficient between the turbine rotation angular velocity ω and the medium volume flow rate V is determined by the impeller structure. When the impeller blade lead parameter remains unchanged, the coefficient K is inversely proportional to the area S of the turbine cross-section where the medium can flow, that is, formula ②:

[0031] K=ε1 / S ②

[0032] Where ε1 is a constant related to the impeller structure.

[0033] The turbine is made of magnetic stainless steel. The angular velocity ω of the turbine rotation is measured by the induction component. The measurement signal is a sinusoidal induced electrical signal. The effective signal is the frequency H of the sinusoidal signal. The frequency H is proportional to the angular velocity ω and the number of turbine blades Z, that is, formula ③:

[0034] H=Z×ω ③

[0035] The standard sensing component 7 measures the rotational angular velocity ω1 of the standard turbine group 5, which corresponds to the frequency signal H1, and the comparison sensing component 8 measures the rotational angular velocity ω2 of the variable diameter turbine group 6, which corresponds to the frequency signal H2.

[0036] The frequency signal H1 can be used to calculate the volume flow rate V of the medium flowing through the sensor pipeline. The volume of the ordinary medium is a constant value, and the volume flow rate of the standard turbine group 5 is equal to the volume flow rate of the variable diameter turbine group 6.

[0037] The contrast sensing component 8 is located at the front end of the flow channel, and the pressure F1 felt by its disc is proportional to the medium mass flow Q, that is, formula ④:

[0038] F1=ε2×Q ④

[0039] ε2 is a constant related to the disk structure.

[0040] The pressure rod 65 moves inward after sensing the pressure, and at the same time drives the connecting rod 64 to move. The movement of the connecting rod 64 causes the variable slider 63 to move along the specified trajectory. However, there is a tension rod 66 connecting the sliding blocks. The tension rod 66 can be regarded as a spring, and its elastic force will prevent the movement of the slider. When the elastic force F2 of the tension rod 66 and the pressure F1 of the pressure rod 65 form a balance, the movement of the variable slider 63 stops, and the moving distance h1 of the variable slider 63 is proportional to the mass flow rate of the medium, that is, formula ⑤:

[0041] h1=ε3×F1⑤

[0042] ε3 is a constant related to the structure of the tension rod 66 and the connecting rod 64. When the variable slider 63 moves outward, part of its surface is exposed outside the inner diameter d of the variable diameter magnetic turbine blade 62, which causes the inner diameter d of the variable diameter magnetic turbine blade 62 to change. This change causes the area S of the turbine cross section where the medium can flow to decrease. The change △S is proportional to the moving distance of the variable slider 63, that is, the formula:

[0043] △S=ε4×h1⑥

[0044] ε4 is a constant related to the variable slider 63 and the impeller structure.

[0045] According to formulas ②~⑥, △S and medium mass flow rate Q are in corresponding relationship, that is, formula ⑦:

[0046] △S=ε2ε3ε4×Q ⑦

[0047] That is, the coefficient K2 of the variable-diameter turbine group 6 is a variable, while the coefficient K1 of the standard turbine group 5 is a fixed value and is not affected by the medium flow rate.

[0048] According to the above characteristics, the frequency H1 of the output signal of the standard induction component 7 is measured first, combined with the coefficient K1 of the standard turbine group 5 to solve the medium volume flow V, and then the coefficient K2 of the variable diameter turbine group 6 is solved by combining the volume flow V with the frequency H2 of the output signal of the comparison induction component 8, that is, formula ⑧:

[0049] K2=V×Z / H2⑧

[0050] When there is no flow, the combined inner diameter of the variable-diameter turbine group 6 is the smallest. At this time, the turbine size of the variable-diameter turbine group 6 is the same as that of the standard turbine group, so the coefficient K 2的 The initial value is equal to K1. When the medium mass flow rate is Q, K2 decreases due to the movement of the variable slider 63, resulting in a decrease in the area S of the turbine cross section where the medium can flow. The change is obtained according to equation ⑦ and equation ②, equation 9:

[0051] K1-K2=ε1×[1 / S - 1 / (S-△S)] ⑨

[0052] Then we can get the functional relationship between the difference between K1 and K2 and the medium mass flow rate Q (⑩):

[0053] ⑩

[0054] Thus, the volume flow rate V and mass flow rate Q are measured, and the medium density ρ is calculated according to formula ⑾:

[0055] ρ=Q / V ⑾

[0056] Embodiment 2:

[0057] Based on the above embodiment, this embodiment further defines the structure of the variable diameter turbine group 6, such as Figure 2 , Figure 4 As shown, the variable diameter turbine group 6 includes a variable diameter turbine shaft 61 with a hollow interior, a variable diameter magnetically conductive turbine blade 62 is fixed in the middle of the variable diameter turbine shaft 61, and the inner wall of the variable diameter turbine shaft 61 between the adjacent variable diameter magnetically conductive turbine blades 62 is provided with a guide groove, and a variable slider 63 is installed in the guide groove, and each of the variable sliders 63 is fixedly connected to a connecting rod 64 at the rear end, and the other ends of all the connecting rods 64 are fixed to the end of a pressure rod 65, and the other end of the pressure rod 65 extends from the rear end of the variable diameter turbine shaft 61 and is provided with a pressure plate. The other parts of this embodiment are the same as the above embodiment and are not repeated here.

[0058] Embodiment 3:

[0059] Based on the above embodiment, this embodiment further defines the structure of the variable diameter turbine group 6, such as Figure 2 , Figure 4 As shown, at least one group of the variable sliders 63 symmetrically arranged are further provided with tension rods 66. However, the sliders are connected by tension rods 66, which can be regarded as springs, and their elastic force will prevent the sliders from moving. When the elastic force F2 of the tension rods 66 and the pressure F1 of the pressure rods 65 form a balance, the movement of the variable sliders 63 stops. The other parts of this embodiment are the same as those of the above embodiment and will not be repeated.

[0060] Embodiment 4:

[0061] Based on the above embodiment, this embodiment further defines the structure of the variable diameter turbine group 6, such as Figure 1 , Figure 2 , Figure 4As shown, bearings 9 are provided at both ends of the variable-diameter turbine shaft 61, and the bearing 9 at the front end of the variable-diameter turbine shaft 61 is embedded in the rear side of the fixed guide 3, and the bearing 9 at the rear end of the variable-diameter turbine shaft 61 is embedded in the front side of the rear end guide 4, so that the variable-diameter turbine group 6 is rollingly fixed between the fixed guide 3 and the rear end guide 4, and the pressure rod 65 is inserted in the rear end of the variable-diameter turbine shaft 61, and the pressure rod 65 can slide back and forth at the rear end of the variable-diameter turbine shaft 61, so that the connecting rod 64 is deformed, pushing or pulling the variable slider 63 to reciprocate in the guide groove. The other parts of this embodiment are the same as the above embodiment and will not be repeated.

[0062] Embodiment 5:

[0063] Based on the above embodiment, this embodiment further defines the structure of the standard turbine group 5, such as Figure 1 As shown, the standard turbine group 5 includes a standard turbine shaft 51, a standard magnetically conductive turbine blade 52 is fixed in the middle of the standard turbine shaft 51, bearings 9 are arranged at both ends of the standard turbine shaft 51, the bearing 9 at the front end of the standard turbine shaft 51 is embedded in the rear side of the front guide 2, and the bearing 9 at the rear end of the standard turbine shaft 51 is embedded in the front side of the fixed guide 3, so that the standard turbine group 5 is rollingly fixed between the front guide 2 and the fixed guide 3. The other parts of this embodiment are the same as the above embodiment and will not be repeated.

[0064] Embodiment 6:

[0065] Based on the above embodiments, this embodiment further defines the structure of the standard sensing component 7, such as Figure 3 As shown, the standard induction component 7 includes a packaging shell 71 fixed to the outer wall of the pipeline shell 1, a coil frame 72 is packaged in the packaging shell 71, a magnet 73 is embedded and fixed in the middle of the coil frame 72, a plurality of turns of enameled wire 74 are wound and fixed on the outer side of the coil frame 72, and one end of the magnet 73 is exposed from the packaging shell 71 and extends toward the inner side of the pipeline shell 1. The other parts of this embodiment are the same as the above embodiment and will not be repeated.

[0066] Embodiment 7:

[0067] Based on the above embodiment, this embodiment further defines the positional relationship between the standard sensing component 7 and the comparison sensing component 8, such as Figure 1 As shown, the structure of the standard induction component 7 is the same as that of the comparison induction component 8. The position where the standard induction component 7 is embedded on the surface of the pipeline shell 1 matches the position where the standard turbine group 5 is located, and the position where the comparison induction component 8 is embedded on the surface of the pipeline shell 1 matches the position where the variable-diameter turbine group 6 is located. The other parts of this embodiment are the same as those of the above embodiment and will not be repeated.

[0068] Embodiment 8:

[0069] Based on the above embodiments, this embodiment further defines the fixing method of the front guide 2, the rear guide 4 and the pipeline housing 1, such as Figure 1 As shown, the front guide 2 and the rear guide 4 are both fixed in the inner positioning groove by a retaining ring 10. The other parts of this embodiment are the same as those of the above embodiment and will not be described in detail.

[0070] It can be understood that the working principle and working process of the variable inner diameter twin-turbine flow measurement sensor structure according to an embodiment of the present invention, such as the standard turbine group 5 and the standard sensing assembly 7, are all prior art and are well known to technicians in this field, and will not be described in detail here.

[0071] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A variable inner diameter twin turbine flow measurement sensor, characterized in that: The invention comprises a pipeline shell (1), wherein a front end guide (2), a fixed guide (3), and a rear end guide (4) are arranged in sequence from front to rear inside the pipeline shell (1), wherein the front end guide (2) and the rear end guide (4) are fixed to the inner wall of the pipeline shell (1); a standard turbine group (5) is installed between the front end guide (2) and the fixed guide (3), a variable diameter turbine group (6) is installed between the fixed guide (3) and the rear end guide (4), and the fixed guide (3) is connected to the standard turbine group (5) and the variable diameter turbine group (6) through the standard turbine group (5) and the variable diameter turbine group (6) ) is fixed between the front guide (2) and the rear guide (4); the surface of the pipeline shell (1) is also embedded with a standard sensing component (7) for detecting the rotation speed of the standard turbine group (5), and a comparison sensing component (8) for detecting the rotation speed of the variable diameter turbine group (6); the variable diameter turbine group (6) includes a variable diameter turbine shaft (61) with a hollow interior, a variable diameter magnetically conductive turbine blade (62) is fixed in the middle of the variable diameter turbine shaft (61), and the inner wall of the variable diameter turbine shaft (61) between adjacent variable diameter magnetically conductive turbine blades (62) is provided with a guide groove. A variable slider (63) is installed in the guide groove, and a connecting rod (64) is fixedly connected to the rear end of each variable slider (63), and the other ends of all the connecting rods (64) are fixed to the end of a pressure rod (65), and the other end of the pressure rod (65) extends from the rear end of the variable diameter turbine shaft (61) and is provided with a pressure plate; a tension rod (66) is also provided between at least one group of the variable sliders (63) that are symmetrically arranged; bearings (9) are provided at both ends of the variable diameter turbine shaft (61), and the variable diameter turbine shaft ( The bearing (9) at the front end of the variable diameter turbine shaft (61) is embedded in the rear side of the fixed guide (3), and the bearing (9) at the rear end of the variable diameter turbine shaft (61) is embedded in the front side of the rear end guide (4), so that the variable diameter turbine group (6) is rollingly fixed between the fixed guide (3) and the rear end guide (4), and the pressure rod (65) is inserted in the rear end of the variable diameter turbine shaft (61), and the pressure rod (65) can slide back and forth at the rear end of the variable diameter turbine shaft (61), so that the connecting rod (64) is deformed, pushing or pulling the variable slider (63) to reciprocate in the guide groove.

2. A variable inner diameter twin turbine flow measurement sensor according to claim 1, characterized in that: The standard turbine assembly (5) comprises a standard turbine shaft (51), a standard magnetically conductive turbine blade (52) is fixed in the middle of the standard turbine shaft (51), bearings (9) are arranged at both ends of the standard turbine shaft (51), the bearing (9) at the front end of the standard turbine shaft (51) is embedded in the rear side of the front end guide (2), and the bearing (9) at the rear end of the standard turbine shaft (51) is embedded in the front side of the fixed guide (3), so that the standard turbine assembly (5) is rollingly fixed between the front end guide (2) and the fixed guide (3).

3. The variable inner diameter twin-turbine flow measurement sensor according to claim 1, characterized in that: The standard induction component (7) comprises a packaging shell (71) fixed to the outer wall of the pipeline shell (1), a coil frame (72) is encapsulated in the packaging shell (71), a magnet (73) is embedded and fixed in the middle of the coil frame (72), a plurality of turns of enameled wire (74) are wound and fixed on the outside of the coil frame (72), and a magnet (73) is fixed in the middle, with one end of the magnet (73) protruding from the packaging shell (71) and extending toward the inside of the pipeline shell (1).

4. A variable inner diameter twin-turbine flow measurement sensor according to claim 3, characterized in that: The standard induction component (7) and the comparison induction component (8) have the same structure. The position at which the standard induction component (7) is embedded in the surface of the pipeline shell (1) matches the position at which the standard turbine group (5) is located. The position at which the comparison induction component (8) is embedded in the surface of the pipeline shell (1) matches the position at which the variable-diameter turbine group (6) is located.

5. The variable inner diameter twin-turbine flow measurement sensor according to claim 1, characterized in that: The front end guide (2) and the rear end guide (4) are both fixed in the positioning groove on the inner side of the pipeline shell (1) via a retaining ring (10).

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