Railway digital signal cable

Abstract

The invention discloses a railway digital signal cable, the cable core of which at least includes a star-shaped four-wire group; a monitoring capacitor plate assembly is arranged between the inner tape layer and the outer tape layer of the star-shaped four-wire group, the monitoring capacitor plate on each side is composed of a plurality of capacitor plate units, the lengths of the capacitor plate units are not equal, the expansion angle α of the capacitor plate units is 90°-120°, and the capacitor plate units are connected in parallel by capacitor connecting lines; the wire group shielding structure includes a wire group shielding corrugated belt and a wire group shielding support ring supported in the wire group shielding corrugated belt at intervals; the overall shielding structure includes an overall shielding corrugated belt and a shielding support ring supported in the overall shielding corrugated belt at intervals; the armor layer includes an inner layer wrapped steel belt and an outer layer wrapped steel belt, and a rubber sealing belt is embedded between the overlapping sections of the inner layer wrapped steel belt and the outer layer wrapped steel belt. The signal cable can effectively monitor the timely operation status of the cable and has good pressure resistance and water resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a railway signal cable used for connecting relevant equipment and control devices in a railway signal system. Background Art

[0002] Railway signal cables are essential wires and cables for signal transmission and energy transmission in railway construction. They are key components for connecting relevant equipment and control devices in railway signal systems and are the nerve center of railway operation control systems. Especially with the continuous speed increase of railways and the development trend of high-speed railways entering digitalization, intelligence and integration, the reliability and safety of railway signal cables have become the top priority for the efficient operation of high-speed railway systems. Therefore, railway digital signal cables not only meet the original railway signal cable indicators, but also improve the comprehensive performance of cables, reduce the capacitance indicator by 40%, increase the insulation resistance indicator by 2.3 times, and optimize the impedance, attenuation and crosstalk performance.

[0003] Internally shielded railway digital signal cables have obvious advantages in digital signal transmission due to their transmission signal stability and excellent anti-interference performance, and account for a high proportion of the cables used in existing railway construction. Currently, there are two basic structures of railway digital signal cables, one is aluminum-polyethylene integrated sheath structure cable, and the other is aluminum sheath structure cable, whose cable core mainly includes an internally shielded four-wire group. With the continuous growth of high-speed railways, the complexity of the laying environment, and the further stringent installation and laying requirements, more stringent requirements are placed on the safety and reliability of signal cable operation: First, the conductor structure stability and conductor impedance of the inner shielded four-wire group will affect the safe and accurate transmission of the cable analog signals, digital signals and control information. However, in the process of manufacturing, laying and operation of digital signal cables, the four conductors of the four-wire group will undergo unexpected changes in the structural position, irregular stretching and shrinkage. In particular, when the railway signal cable is in an environment where it passes through special terrain or the terrain creeps during laying, the cable will be subjected to greater longitudinal tension. The increase in these longitudinal tensions will cause irregular radial shrinkage and deformation of the cable conductor, and may even cause the four-wire group conductor to break, which is very dangerous to high-speed locomotives. However, these changes in the conductor structure of the wire group cannot be timely monitored and discovered in the existing railway digital signal cables. Secondly, the existing wire group shielding is a shielding structure formed by wrapping a four-wire group with a metal foil tape. However, the signal cable will be subjected to rolling and bending during the laying and use process, and the metal shielding foil tape cannot withstand the rolling and bending caused by external forces. The rolling and bending caused by such external forces will not only destroy the stability of the position structure of the four-wire group conductor, but also cause the insulation of the wire group The single wire and the conductor are compressed and flattened or even broken, which will not only affect the mechanical strength and surface smoothness of the insulation single wire, but also affect the coaxial capacitance, concentricity and ellipticity of the insulation single wire, and then affect the electrical performance of the cable. Obviously, the existing shielding structure of the four-wire group cannot effectively protect the wire group conductor. Third, the use area of ​​railway digital signal cables is very complex, especially for signal cables that are in a humid or water-corroded environment for a long time. The aging and cracking of the cable sheath will cause water or water vapor to penetrate into the cable, which is easy to cause the electrical performance of the cable to deteriorate, and the conductor to be corroded and oxidized, which seriously affects the reliable and accurate transmission of the control signal and seriously reduces the safety and service life of the signal cable. At the same time, although the metal sheath of the existing railway digital signal cable has a certain shielding effect, the main function of the sheath is still to protect the cable core. Therefore, the shielding performance of this type is still insufficient, and there is a lack of reliable shielding of physical parameters such as external signals and chaotic electromagnetic waves, which directly affects the safe and reliable transmission of control signals. This is particularly prominent in high-reliability and high-safety applications such as high-speed railways and urban light rails. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a railway digital signal cable, which can not only effectively monitor the timely operation status of the cable, but also has good pressure resistance and water resistance.

[0005] In order to solve the above technical problems, the railway digital signal cable of the present invention comprises a cable core, wherein the cable core comprises at least one star-shaped quad-wire group, the star-shaped quad-wire group is formed by twisting four insulating single wires, and the insulating layers of the insulating single wires are three layers, namely, a solid inner skin layer, an intermediate foam layer and a solid outer skin layer, from the conductor to the outside; the star-shaped quad-wire group is coated with a wire group inner tape layer, a wire group outer tape layer, a wire group shielding structure and a wire group outer sheath from the inside to the outside, and a monitoring capacitor plate assembly is arranged between the wire group inner tape layer and the wire group outer tape layer, and the monitoring capacitor plate assembly comprises relatively arranged monitoring capacitor plates, and the monitoring capacitor plates on each side are composed of a plurality of capacitor plate units arranged in the longitudinal direction, and each capacitor plate unit is provided. The lengths of the elements are not equal, the expansion angle α of the capacitor plate unit is 90°-120°, and the capacitor plate units on the same side are connected in parallel by at least one capacitor connecting line; the wire group shielding structure includes a wire group shielding corrugated belt and a wire group shielding support ring supported in the wire group shielding corrugated belt at intervals; the cable core is sequentially coated with a tape layer, an inner sheath, a total shielding structure, an inner cushion layer, an armor layer and an outer sheath from the inside to the outside; the total shielding structure includes a total shielding corrugated belt and a shielding support ring supported in the total shielding corrugated belt at intervals; the armor layer includes a wrapped inner layer wrapped steel belt and an outer layer wrapped steel belt, and a rubber sealing belt is embedded between the overlapping sections of the inner layer wrapped steel belt and the outer layer wrapped steel belt.

[0006] Compared with the prior art, the railway digital signal cable of the present invention has at least the following significant advantages:

[0007] Firstly, since a monitoring capacitor plate assembly is arranged between the inner tape layer and the outer tape layer of the wire group, the relatively arranged monitoring capacitor plates are composed of a plurality of capacitor plate units arranged in the longitudinal direction, and the relatively arranged monitoring capacitor plates constitute a capacitive monitoring sensor element, when the physical quantities such as the structural position of the four-wire group and the wire group conductor between the two monitoring capacitor plates and the conductor cross-sectional shape change, the relative dielectric constant ε will also change, and the monitoring capacitor plate converts these changes into changes in capacitance, and then converts them into corresponding electrical signal outputs through the capacitor connecting wire and the conversion circuit, so as to monitor the operating status of each group of four-wire groups of the signal cable. The use of capacitive sensor devices has the characteristics of simple structure, good dynamic response and good temperature stability.

[0008] Since the plate lengths of the capacitor plate units arranged longitudinally along the cable are not equal, the position of the line group fault on the cable length can be accurately located according to the capacitance change rate corresponding to the plates of different lengths; the initial capacitance of any relatively arranged monitoring capacitor plate is C0=ε0S / d (where ε0 is the initial dielectric constant, S is the area covered by the two plates, and d is the distance between the two plates; when the physical quantities such as the line group and the line group conductor between the monitoring capacitor plates change, the dielectric constant changes to ε1, while S / d remains unchanged, and the capacitance is C1=ε1S / d. The change rate of the monitoring capacitance at this position reflected by the monitoring capacitor plate is △C / C0=(C1-C0) / C0=(ε1-ε0) / ε0. Since the plate lengths of the capacitor plate units arranged longitudinally along the cable are not equal, the initial capacitance of each capacitor plate unit and the change rate of the monitoring capacitance are also different. According to the different monitoring capacitance change rates, the position of the cable line group fault point can be determined, and a maintenance plan can be formulated, thereby well maintaining the signal cable in a safe and reliable operating state at all times.

[0009] Furthermore, since each wire group shielding structure includes a wire group shielding corrugated belt and a wire group shielding support ring supported in the wire group shielding corrugated belt, the corrugated shielding layer not only has a relatively stable shielding performance, but also can enhance the bending flexibility of the wire group and the cable, avoid bending, extrusion and deformation of the insulated single wire and the insulated conductor when the cable and the wire group are bent, and can effectively ensure the stability and firmness of the insulated single wire structure. The annular shielding support ring embedded in the inner side of the shielding corrugated belt can effectively support and withstand the pressure of the shielding wire group by external force, forming a reliable protection structure, improving the anti-extrusion mechanical performance of the shielded four-wire group, not only can ensure the stability, coaxial capacitance, concentricity and roundness of the insulated single wire structure in the shielding layer, but also can avoid the occurrence of the phenomenon of the insulation layer and the conductor being crushed or broken, forming a dual effect of shielding and protection.

[0010] Similarly, the overall shielding structure also adopts the structure of overall shielding corrugated tape and shielding support ring, replacing the aluminum sheath shielding structure in the existing signal cable with overall shielding corrugated tape and shielding support ring, which not only greatly reduces the weight and overall size of the signal cable, but also makes the signal cable more flexible in laying, and can form a firm and stable protection structure, maintain the structural stability of each four-wire group in the cable core, and maintain the mechanical properties of the signal cable such as compression and impact resistance.

[0011] The armor structure of the signal cable adopts a two-layer wrapped steel tape structure, and a rubber sealing tape is embedded between the overlapping sections of the inner and outer wrapped steel tapes, forming a zero-leakage overlapping structure, so that the wrapped armor steel tape forms a closed tubular space, which not only enhances the tensile and compressive strength and improves the cable's anti-interference performance, but also has extremely high sealing performance, completely avoiding the penetration and intrusion of moisture into the cable along the radial direction, and has reliable and strict waterproof performance.

[0012] The insulation layer of the insulated single wire adopts a three-layer structure of a solid inner layer, a middle foam layer and a solid outer layer, which greatly reduces the working capacitance between the insulated single wires and reduces the transmission attenuation constant of the wire group.

[0013] In a further embodiment of the present invention, the lengths of adjacent capacitor plate units increase or decrease in multiples along the longitudinal direction, and the lengths of capacitor plate units arranged opposite to each other are equal. This structure facilitates distinguishing the size of capacitance change rate, thereby accurately positioning.

[0014] In a preferred embodiment of the present invention, the longest capacitor plate unit among the capacitor plate units is located in the middle of the longitudinal direction of the star quadrifilar group, and the lengths of the capacitor plate units from the longest capacitor plate unit to the two ends of the longitudinal direction of the star quadrifilar group decrease in multiples; the capacitor plate units arranged from the middle to the two ends of the star quadrifilar group are respectively connected in parallel with corresponding capacitor connecting lines. The expansion angle α of the capacitor plate unit is 100°. This structure is conducive to accurately locating the fault point of a signal cable with a long length.

[0015] In a preferred embodiment of the present invention, the wire group shielding corrugated belt is a corrugated copper belt, and the wire group shielding support ring is embedded in the corrugated groove corresponding to the wire group shielding corrugated belt. The wire group shielding support ring is made of carbon fiber, and the wire group shielding support ring is composed of a shielding upper support ring and a shielding lower support ring, and the shielding upper support ring and the shielding lower support ring are plugged into each other by a support ring tenon and a support ring groove. The structure is reasonable, easy to manufacture and assemble, and can effectively enhance the pressure bearing capacity of the support ring.

[0016] In a preferred embodiment of the present invention, the overall shielding corrugated belt is a corrugated copper belt, and the shielding support ring is embedded in the corrugated groove corresponding to the overall shielding corrugated belt. The shielding support ring is made of carbon fiber, and the shielding support ring is composed of an upper support ring and a lower support ring, and the upper support ring and the lower support ring are plugged into each other by a plug-in tenon and a plug-in groove. The structure is reasonable, easy to manufacture and assemble, and the support ring has a strong pressure bearing capacity.

[0017] In a further embodiment of the present invention, the inner layer wrapped steel belt is spirally wrapped on the inner cushion layer at intervals; the outer layer wrapped steel belt is spirally wrapped on the inner layer wrapped steel belt at intervals. The distance between the two adjacent sides of the spirally wrapped inner layer wrapped steel belt or the outer layer wrapped steel belt is less than half of the width of the steel belt. The mechanical strength of the cable is effectively enhanced, and the anti-corrosion ability and water-blocking performance of the cable are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The railway digital signal cable of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0019] Figure 1 It is a schematic diagram of the cross-sectional structure of a specific implementation of the railway digital signal cable of the present invention;

[0020] Figure 2yes Figure 1 The schematic cross-sectional structure diagram of the overall shielding structure in the railway digital signal cable is shown;

[0021] Figure 3 yes Figure 2 A schematic diagram of the cross-sectional structure of the upper support ring in the overall shielding structure shown;

[0022] Figure 4 yes Figure 3 Schematic diagram of the left view structure;

[0023] Figure 5 yes Figure 2 A schematic diagram of the cross-sectional structure of the lower support circle in the overall shielding structure shown;

[0024] Figure 6 yes Figure 5 Schematic diagram of the left view structure;

[0025] Figure 7 yes Figure 1 The schematic diagram of the cross-sectional structure of the armor layer in the railway digital signal cable is shown;

[0026] Figure 8 yes Figure 1 The schematic diagram of the cross-sectional structure of the insulated single wire and star-shaped four-wire group in the railway digital signal cable shown;

[0027] Fig. 9 yes Figure 8 A schematic diagram of the structure of the monitoring capacitor assembly in the star-shaped quad-wire unit shown;

[0028] Fig.10 yes Figure 8 A schematic cross-sectional structure diagram of a pair of monitoring capacitor plate units arranged opposite to each other in the four-wire group unit shown;

[0029] Fig.11 yes Figure 1 A schematic cross-sectional structure diagram of a wire group shielding structure in a railway digital signal cable is shown;

[0030] Fig.12 yes Fig.11 A schematic diagram of the cross-sectional structure of the shielding support ring of the center line group in the structure shown;

[0031] Fig.13 yes Fig.12 A schematic diagram of the cross-sectional structure of the shielding upper support ring in the structure shown;

[0032] Fig.14 yes Fig.13 a left side view of the structure shown;

[0033] Fig.15 yes Fig.12 A schematic diagram of the cross-sectional structure of the shielding lower support ring in the structure shown;

[0034] Fig.16 yes Fig.15 Left side view of the structure shown.

[0035] In the figure, 1 is an outer sheath, 2 is an armor layer, 21 is an inner layer of steel tape, 22 is an outer layer of steel tape, 23 is a rubber sealing tape, 3 is an inner cushion layer, 4 is a total shielding layer, 41 is a total shielding corrugated tape, 42 is a shielding support ring, 43 is an upper support ring, 44 is a plug-in tenon, 45 is a lower support ring, 46 is a plug-in slot, 5 is an inner sheath, 6 is a tape layer, 7 is an insulated single wire, 71 is a conductor, 8 is a star-shaped four-wire group, 81 is a tape layer inside the wire group, 82 is a monitoring capacitor assembly, 821 is a monitoring capacitor plate, 822 is a capacitor connecting line, 823 is a capacitor plate unit, 83 is a tape layer outside the wire group, 84 is a wire group shielding structure, and 85 is a wire group outer sheath. DETAILED DESCRIPTION

[0036] like Figure 1 The railway digital signal cable shown in the figure has a cable core formed by twisting four star-shaped quad wires 8. Of course, the number of star-shaped quad wires in the cable core is not limited to four, but the number of star-shaped quad wires is at least one. In addition to the star-shaped quad wires, the cable core may also include a twisted pair group or / and an insulated single wire. The number or color of the star-shaped quad wires and twisted pair groups of the cable core is generally determined according to the design requirements and the railway industry standard "Railway Signal Cable". The cable core is coated with a tape layer 6, an inner sheath 5, a total shielding structure 4, an inner cushion layer 3, an armor layer 2 and an outer sheath 1 from the inside to the outside. The tape layer 6 is composed of one layer of insulating tape with a thickness of 0.05 mm and two layers of insulating tape with a thickness of 0.2 mm; the inner sheath 5 is a polyethylene sheath with a thickness of 1 mm; the inner cushion layer 3 is a polyethylene sheath with a thickness of 1.3 mm, and the outer sheath 1 is a low-smoke, halogen-free, flame-retardant sheath with a thickness of 2.1 mm.

[0037] like Figure 2 As shown, the total shielding structure 4 includes a total shielding corrugated belt 41, which adopts a commonly used corrugated copper belt, and annular shielding support rings 42 are supported on the inner wall surface of the total shielding corrugated belt 41 at intervals. By adjusting the spacing between two adjacent shielding support rings 42, the pressure-bearing strength of the shielding structure can be changed to adapt to different use environments. The shielding support ring 42 is just embedded in the corrugated groove corresponding to the total shielding corrugated belt 41, so that the shielding support ring 42 is relatively stably fixed on the inner wall surface of the total shielding corrugated belt 41. The annular shielding support ring 42 is made of carbon fiber material, and has the characteristics of light weight and high strength. The shielding support ring 42 is composed of an upper support ring 43 and a lower support ring 45.

[0038] like Figure 3 , Figure 4 As shown, the upper support ring 43 is a semicircular ring, and both ends of the semicircular ring are provided with a trapezoidal plug-in tenon 44. Figure 5 , Figure 6 As shown, the lower support ring 45 is also a semicircular ring, and both ends of the semicircular ring are provided with a concave trapezoidal cross-section plug-in groove 46, and the cross-sectional shapes of the plug-in tenon 44 and the plug-in groove 46 are consistent with each other, so as to be plugged into each other to form a shielding support ring 42 with a full ring structure.

[0039] like Figure 7 As shown, the armor layer 2 adopts a double-layer steel tape wrapped structure, and the armor layer 2 includes an inner wrapped steel tape 21 and an outer wrapped steel tape 22. The inner wrapped steel tape 21 is spirally wrapped on the inner cushion layer 3, and the outer wrapped steel tape 22 is also spirally wrapped on the inner wrapped steel tape 21. The distance between the adjacent sides of the spirally wrapped inner wrapped steel tape 21 or the outer wrapped steel tape 22 should be less than or equal to half of the steel tape width. In this embodiment, the steel tape width of the inner wrapped steel tape 21 or the outer wrapped steel tape 22 is B, and the distance between the adjacent sides of the same steel tape is b, b=0.45B, preferably b=(0.40-0.50)B, but the spacing should be less than half of the steel tape width. A corresponding embedding groove is provided between the overlapping sections of the inner wrapped steel belt 21 and the outer wrapped steel belt 22, in which a rubber sealing belt 23 is embedded. Therefore, the rubber sealing belt 23 is also spirally embedded between the overlapping sections of the inner wrapped steel belt 21 and the outer wrapped steel belt 22, thereby forming a strict water-blocking and waterproof structure.

[0040] like Figure 8 The star-shaped quad wire group 8 in the cable core shown is twisted by four insulated single wires 7. The conductor 71 of the insulated single wire is a metal copper wire with a diameter of 0.995 mm. An insulating layer is coated on the outside of the conductor 71. The outer diameter of the insulating layer is 2.75 mm. The insulating layer is composed of a three-layer structure, which is a solid inner skin layer, a middle foam layer and a solid outer skin layer from the conductor 71 to the outside. The four mutually twisted insulated single wires 7 are coated with a wire group inner tape layer 81, a wire group outer tape 83, a wire group shielding structure 84 and a wire group outer sheath 85 from the inside to the outside. The wire group inner tape layer 81 is wrapped by an insulating tape with a thickness of 0.05 mm, and the wire group outer tape layer 83 is also wrapped by an insulating tape with a thickness of 0.05 mm. The wire group outer sheath 85 is extruded from a polyethylene material. A monitoring capacitor plate assembly 82 is provided between the inner tape layer 81 of the wire group and the outer tape layer 83 of the wire group. The monitoring capacitor plate assembly 82 is symmetrically arranged on both sides of the axis of the star-shaped quad wire group 7, thereby forming a monitoring capacitive sensor.

[0041] like Fig. 9As shown, the monitoring capacitor plates 821 located on both sides of the axis of the star-shaped quadrifilar group are composed of a plurality of capacitor plate units 823 arranged along the length direction of the axis, and the lengths of each unit plate of each capacitor plate unit 823 are not equal. In this embodiment, since the cable is long, the longest capacitor plate units 823 are on both sides of the middle position of the cable length. The unit plate lengths of the capacitor plate units 823 from the longest capacitor plate unit 823 to the capacitor plate units 823 at the two ends of the star-shaped four-wire group decrease in multiples. For example, if the longest capacitor plate unit 823 is L, the lengths of the capacitor plate units 823 at the two ends are 1 / 2L, 1 / 4L, 1 / 8L, 1 / 16L, ... respectively. In this way, the capacitance change rates of the capacitor plate units 823 caused by the fault are different, and the numerical differences are relatively large, which is conducive to accurately determining the location of the fault. From the longest capacitor plate unit 823 in the middle to each capacitor plate unit 823 at the two ends, they are connected in parallel with the corresponding capacitor connecting lines 822. Therefore, the star-shaped four-wire group has two corresponding capacitor connecting lines 822 from the middle to the end. Of course, the plate length of the capacitor plate unit 823 can also be continuously increased in multiples from one end to the other end, such as the length of each plate from one end of the star quad group to the other end is L, 2L, 4L, 8L, .... The capacitor plate units 823 on the same side are connected in parallel to each other through the capacitor connection line 822, and the extended end of the capacitor connection line 822 is connected to the monitoring conversion circuit to convert it into a corresponding electrical signal.

[0042] like Fig.10 As shown, the corresponding capacitor plate units 823 located on both sides of the axis of the star quad group 8 are symmetrical arc-shaped plate units, and the capacitor plate units 823 are thin copper sheets. The expansion angle α of the capacitor plate unit 823 is 100°. Of course, the expansion angle α of the capacitor plate unit 823 should preferably be controlled to α=90°-120°.

[0043] like Fig.11 and Fig.12 The wire group shielding structure shown in the figure includes a wire group shielding corrugated belt 841, and the wire group shielding corrugated belt 841 adopts a commonly used corrugated copper belt, and an annular wire group shielding support ring 842 is supported on the inner wall surface of the wire group shielding corrugated belt 841 at intervals. By adjusting the spacing between two adjacent wire group shielding support rings 842, the pressure-bearing strength of the shielding structure can be changed to adapt to different use environments. The wire group shielding support ring 842 is just embedded in the corrugated groove corresponding to the wire group shielding corrugated belt 841, so that the wire group shielding support ring 842 is relatively stably fixed on the inner wall surface of the wire group shielding corrugated belt 841. The annular wire group shielding support ring 842 is made of carbon fiber material, and has the characteristics of light weight and high strength.

[0044] like Fig.12 As shown, the wire group shielding support ring 842 is composed of a shielding upper support ring 843 and a shielding lower support ring 845. Fig.13 , Fig.14 As shown, the shielding upper support ring 843 is a semicircular ring, and both ends of the semicircular ring are trapezoidal support ring tenons 844. Fig.15 , Fig.16 As shown, the shielding lower support ring 845 is also a semicircular ring, and a support ring groove 846 with a concave trapezoidal cross-section is provided at both ends of the semicircular ring. The cross-sectional shapes of the support ring tenon 844 and the support ring groove 846 are consistent with each other, so as to be plugged into each other to form a wire group shielding support ring 8 with a full ring structure.

[0045] The above only lists a preferred implementation mode of the present invention, but the present invention is not limited to this embodiment. Many improvements and changes can be made without violating the basic principles of the present invention, and these improvements and changes all fall within the protection scope of the present invention.

Claims

1. A railway digital signal cable, comprising a cable core, characterized in that: The cable core comprises at least one star-shaped quad-wire group (8), the star-shaped quad-wire group (8) being formed by twisting four insulated single wires (7), the insulating layers of the insulated single wires (7) being three layers, namely, a solid inner skin layer, an intermediate foam layer and a solid outer skin layer, from the conductor (71) to the outside; the star-shaped quad-wire group (8) is coated with a wire group inner tape layer (81), a wire group outer tape layer (83), a wire group shielding structure (84) and a wire group outer sheath (85) in sequence from the inside to the outside, the wire group inner tape layer (81) and the wire group outer tape layer (83) being ) is provided between the two monitoring capacitor plates, the monitoring capacitor plate assembly (82) comprising monitoring capacitor plates (821) arranged opposite to each other, the monitoring capacitor plates (821) on each side are composed of a plurality of capacitor plate units (823) arranged in the longitudinal direction, the lengths of the capacitor plate units (823) are not equal, the extension angles α of the capacitor plate units (823) are 90°-120°, and the capacitor plate units (823) on the same side are connected in parallel with each other by at least one capacitor connecting line (822); the line group shielding structure (84 ) comprises a wire group shielding corrugated tape (841) and a wire group shielding support ring (842) supported in the wire group shielding corrugated tape (841) at intervals; the cable core is covered with a tape layer (6), an inner sheath (5), a total shielding structure (4), an inner cushion layer (3), an armor layer (2) and an outer sheath (1) in sequence from the inside to the outside; the total shielding structure (4) comprises a total shielding corrugated tape (41) and a shielding support ring (42) supported in the total shielding corrugated tape (41) at intervals; the armor layer (2) comprises The inner layer of the wrapped steel belt (21) and the outer layer of the wrapped steel belt (22) are wrapped, and a rubber sealing belt (23) is embedded between the overlapping sections of the inner layer of the wrapped steel belt (21) and the outer layer of the wrapped steel belt (22); the lengths of adjacent capacitor plate units (823) increase or decrease in multiples along the longitudinal direction, and the lengths of the capacitor plate units (823) arranged opposite to each other are equal; the wire group shielding corrugated belt (841) is a corrugated copper belt, and the wire group shielding support ring (842) is embedded in the corrugated groove corresponding to the wire group shielding corrugated belt (841).

2. The railway digital signal cable according to claim 1, characterized in that: The longest capacitor plate unit (823) among the capacitor plate units (823) is located in the middle of the star-shaped quadrifilar group (8) in the longitudinal direction, and the lengths of the capacitor plate units (823) from the longest capacitor plate unit (823) to the capacitor plate units (823) at the two ends of the star-shaped quadrifilar group (8) in the longitudinal direction decrease in multiples; the capacitor plate units (823) arranged from the middle to the two ends of the star-shaped quadrifilar group (8) are respectively connected in parallel via corresponding capacitor connecting lines (822).

3. The railway digital signal cable according to claim 1 or 2, characterized in that: The expansion angle α of the capacitor plate unit (823) is 100°.

4. The railway digital signal cable according to claim 1, characterized in that: The wire group shielding support ring (842) is made of carbon fiber, and the wire group shielding support ring (842) is composed of a shielding upper support ring (843) and a shielding lower support ring (845), and the shielding upper support ring (843) and the shielding lower support ring (845) are plugged into each other by a support ring tenon (844) and a support ring groove (846).

5. The railway digital signal cable according to claim 1, characterized in that: The overall shielding corrugated belt (41) is a corrugated copper belt, and the shielding support ring (42) is embedded in the corrugated groove corresponding to the overall shielding corrugated belt (41).

6. The railway digital signal cable according to claim 5, characterized in that: The shielding support ring (42) is made of carbon fiber. The shielding support ring (42) is composed of an upper support ring (43) and a lower support ring (45). The upper support ring (43) and the lower support ring (45) are plugged into each other via a plug-in tenon (44) and a plug-in groove (46).

7. The railway digital signal cable according to claim 1, characterized in that: The inner layer wrapping steel belt (21) is wrapped around the inner cushion layer (3) at intervals in a spiral manner; and the outer layer wrapping steel belt (22) is wrapped around the inner layer wrapping steel belt (21) at intervals in a spiral manner.

8. The railway digital signal cable according to claim 7, characterized in that: The distance between two adjacent sides of the spirally wrapped inner layer steel strip (21) or the spirally wrapped outer layer steel strip (22) is less than half the width of the steel strip.

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