A cable protection pipe hot deformation temperature on-line monitoring device

Abstract

This invention relates to the field of online monitoring technology for power cables, and discloses an online monitoring device for the thermal deformation temperature of cable protection pipes. The device includes a main base with a fixing mechanism for clamping the main base to the outer wall of the monitored cable protection pipe. The main base also has a guide hole and a linear groove. A baffle plate is fixedly clamped onto the cable protection pipe, maintaining an initial distance between the baffle plate and the main base. A measuring rod slides through the guide hole, with a ball head fixed at its first end, abutting against the end face of the baffle plate. A connecting rod is movably connected to the main base, hinged to the main base at its middle section. The first end of the connecting rod is movably connected to the second end of the measuring rod, and a sector gear is fixed at the second end of the connecting rod. This invention uses a planetary gear differential mechanism to mechanically compare the actual displacement with the theoretical thermal expansion in real time. This allows the pointer to remain stationary during normal temperature changes and only deflect and alarm during abnormal thermal displacement, thereby automatically filtering out background interference, avoiding false alarms, and significantly improving monitoring accuracy.

Description

Technical Field

[0001] This invention relates to the field of online monitoring technology for power cables, specifically to an online monitoring device for the thermal deformation temperature of cable protection pipes. Background Technology

[0002] The periodic changes in the load current of high-voltage cables cause conductor temperature fluctuations, resulting in thermomechanical effects that cause repeated expansion and contraction of the cable, potentially leading to fatigue, arching, or even damage to the metal sheath. Existing online cable displacement and temperature monitoring solutions mainly include: using current, temperature, and displacement sensors in conjunction with high-speed DSP acquisition and server software for identification; using a sliding rheostat with a CPU and AD module to measure displacement at bending points; employing fiber optic gratings (FBG) or distributed fiber optic temperature measurement systems (DTS) for continuous temperature monitoring; and analyzing surface deformation images through machine vision.

[0003] Existing technical solutions all rely on external power supplies and electronic signal processing systems, and generally suffer from the following shortcomings: First, dependence on external power supplies poses electrical safety hazards due to the long-term operation of electronic components in cable channels where moisture and flammable gases accumulate. Second, the systems involve multiple components such as sensors, data acquisition cards, communication modules, and host computer software, resulting in complex structures. Daily maintenance requires professional personnel and regular battery replacements, leading to high costs. Third, fiber optic gratings exhibit cross-sensitivity to temperature and strain, necessitating the addition of temperature-compensated gratings or complex demodulation algorithms to distinguish between the two, increasing system complexity and cost. Fourth, the above solutions are all designed for the cable itself; no online monitoring solution for the thermal deformation and displacement of the cable protection conduit has yet been found. Summary of the Invention

[0004] In view of the shortcomings of existing electronic cable online monitoring devices mentioned in the background art, the present invention provides an online monitoring device for the thermal deformation temperature of cable protection pipes, which has the advantages of safety, maintenance-free operation, automatic temperature compensation, and intuitive alarm for abnormal displacement, thus solving the technical problems mentioned in the background art.

[0005] The present invention provides the following technical solution: an online monitoring device for the thermal deformation temperature of a cable protection pipe, characterized in that: it includes a main base (1) on which a fixing mechanism (11) is provided, and the main base (1) is also provided with a guide hole (13) and a straight slide groove (14); a baffle (2) is fixedly clamped on the cable protection pipe, and a measuring rod (3) is slidably inserted in the guide hole (13), and a ball head (33) is fixed at the first end of the measuring rod (3), and the ball head (33) abuts against the end face of the baffle (2); a connecting rod (31) is movably connected on the main base (1), and the connecting rod (31) is hinged to the main base (1) in the middle, and the first end of the connecting rod (31) is movably connected to the second end of the measuring rod (3), and a sector gear (32) is fixed at the second end of the connecting rod (31). It also includes a first input gear (4), a second input gear (63), a bimetallic strip (5), a disc cam (6), and a follower (61); the first input gear (4) is rotatably mounted on the main base (1) and meshes with the sector gear (32), and a gear ring (8) is coaxially fixed on the axle of the first input gear (4); the bimetallic strip (5) is helical, with its helical center end fixed to the main base (1), and its helical outer end serving as a free end against the outer wall of the cable protection pipe; the disc cam (6) is fixedly connected to... The free end of the bimetallic strip (5); the follower (61) is slidably disposed on the main base (1), one end of the follower (61) abuts against the contour surface of the cam (6), and the other end of the follower (61) is fixedly connected to a rack (62); the rack (62) is slidably engaged in the linear groove (14); the second input gear (63) is rotatably mounted on the main base (1) and meshes with the rack (62), and a sun gear (7) is coaxially fixed on the axle of the second input gear (63).

[0006] Preferably, it also includes a planetary carrier, a pointer, and a dial; the planetary carrier is rotatably mounted on the main base (1), and at least two planetary gears are evenly distributed around the circumference of the planetary carrier. Each planetary gear is rotatably mounted on the planetary carrier and simultaneously meshes with the sun gear (7) and the gear ring (8); the pointer is fixedly connected to the shaft end of the planetary carrier; the dial is fixed to the main base (1), and the pointing end of the pointer sweeps across the surface of the dial. The dial is divided into a green safety area and a red alarm area.

[0007] Preferably, the measuring rod (3) is made of Invar alloy, the baffle (2) is made of wear-resistant material, the main base (1) is a rigid frame, and the baffle (2) and the main base (1) maintain an initial distance.

[0008] Preferably, an elastic copper sheet (51) is fixedly connected to the free end of the bimetallic strip (5), the elastic copper sheet (51) is attached to the outer wall of the cable protection tube, and a return spring (64) is provided between the driven member (61) and the main base (1) to force the driven member (61) to be in close contact with the cam.

[0009] Preferably, the profile of the cam (6) is configured such that, within the operating temperature range sensed by the bimetallic strip (5), the rotation angle of the cam (6) is linearly related to the theoretical thermal elongation determined by the thermal expansion coefficient of the cable protection pipe material itself.

[0010] Preferably, the baffle (2) is fixedly clamped to the cable protection pipe by a clamp (21).

[0011] Preferably, the distance from the middle hinge point of the link (31) to its first end is less than the distance to its second end.

[0012] Preferably, the number of planetary gears circumferentially distributed on the planet carrier is two or three.

[0013] Preferably, the return spring (64) is a compression spring, with one end abutting against the driven member (61) and the other end abutting against the main base (1).

[0014] The present invention has the following beneficial effects: 1. This invention uses a planetary gear differential mechanism to mechanically compare the actual displacement with the theoretical thermal expansion in real time. This allows the pointer to remain stationary during thermal expansion and contraction caused by temperature changes in the normal environment, and to deflect and alarm only during abnormal thermal displacement. This automatically filters out background interference, avoids false alarms, and significantly improves the accuracy of monitoring.

[0015] 2. This invention enables the monitoring indicator to operate inherently safely in damp and flammable cable channels by using purely mechanical components such as baffles, measuring rods, and bimetallic strips in synergy, completely eliminating the risk of electrical arcing and short circuits, and ensuring reliable use in long-term harsh environments.

[0016] 3. The present invention uses a first-stage amplification mechanism composed of unequal-arm levers and sector gears, combined with the secondary output of differential planetary gear train, to amplify the micro-scale axial displacement of the protective tube into the centimeter-scale pointer swing on the dial. Inspection personnel can clearly judge the thermal deformation state from a distance, greatly improving inspection efficiency and intuitiveness.

[0017] 4. This invention uses an Invar alloy probe and a spiral bimetallic strip to pick up displacement and temperature respectively, and uses a specially designed cam profile to accurately and linearly map the temperature to the theoretical elongation. This enables the two inputs to perform mechanical differential under the same physical dimension, ensuring that the comparison results are not affected by the thermal expansion and contraction of the probe itself, and guaranteeing the long-term stability and reliability of the alarm threshold.

[0018] 5. This invention, through its fully enclosed mechanical frame and maintenance-free structural design, enables the device to eliminate the need to replace consumable parts such as batteries and sensors. Daily maintenance only requires periodic visual inspection of the dial, significantly reducing the frequency and cost of operation and maintenance. It is particularly suitable for underground enclosed spaces such as cable tunnels that are difficult to access frequently. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the elongation measurement structure of the present invention; Figure 2 This is a schematic diagram of the temperature measuring structure of the present invention.

[0020] In the diagram: 1. Main base; 11. Fixing mechanism; 13. Guide hole; 14. Linear slide; 2. Baffle; 3. Measuring rod; 31. Connecting rod; 32. Sector gear; 33. Ball head; 4. First input gear; 5. Bimetallic strip; 51. Elastic copper strip; 6. Cam; 61. Follower; 62. Rack; 63. Second input gear; 64. Return spring; 7. Sun gear; 8. Gear ring. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 An online monitoring device for the thermal deformation temperature of a cable protection pipe includes a main base 1 serving as an installation reference. The main base 1 is a rigid frame made of stainless steel or high-strength aluminum alloy, possessing good structural stability. A fixing mechanism 11 is provided on the main base 1. During installation, the fixing mechanism 11 securely clamps the main base 1 to the outer wall of the cable protection pipe being monitored, preventing relative sliding. In this embodiment, the fixing mechanism 11 uses bolt clamps. The main base 1 is also machined with guide holes 13 and linear grooves 14. The guide holes 13 provide precise sliding guidance for the measuring rod 3, while the linear grooves 14 constrain the movement trajectory of the rack 62.

[0023] The baffle 2 is fixedly clamped to the cable protection pipe by an independent clamp, and its position ensures that the end face of the baffle 2 maintains an initial distance L0 between the end face of the baffle 2 and the corresponding end face of the main base 1. The baffle 2 is preferably made of wear-resistant material, such as cemented carbide or hardened tool steel, to resist wear that may be caused by repeated contact over a long period of time. The measuring rod 3 is made of Invar alloy, which has an extremely low coefficient of thermal expansion, thus minimizing the impact of ambient temperature changes on the length of the measuring rod itself. The measuring rod 3 slides through the guide hole 13, and its first end is fixed with a ball head 33, which abuts against the end face of the baffle 2 after installation; the second end of the measuring rod 3 is movably connected to the first end of the connecting rod 31. This movable connection can be made by a pin and a slotted hole to allow a small amount of relative rotation when the connecting rod swings.

[0024] The middle part of the connecting rod 31 is hinged to the main base 1 via a hinge shaft. A sector gear 32 is fixedly connected to the second end of the connecting rod 31. Specifically, the distance L1 from the hinge point at the middle of the connecting rod 31 to its first end is less than the distance L2 from the hinge point to its second end, thus forming an unequal-arm lever with a displacement amplification ratio of i = L2 / L1. The small axial displacement at the end of the measuring rod 3 is amplified into a larger angular displacement output by the sector gear 32. The first input gear 4 is rotatably mounted on the main base 1 via bearings and meshes with the sector gear 32. A gear ring 8, an internal gear ring, is coaxially fixedly connected to the axle of the first input gear 4, forming one input end of the differential gear train.

[0025] Please see Figure 2 The bimetallic strip 5 is helical, with its central end fixed to the inner surface of the main base 1, while the outer end of the helix serves as a free end, and is fixedly connected to an elastic copper strip 51 by welding or riveting. The elastic copper strip 51 has good thermal conductivity and flexibility, and always adheres to the outer wall of the cable protection pipe, which can quickly transfer the pipe wall temperature to the bimetallic strip 5 without scratching the pipe wall. A disc-shaped cam 6 is coaxially fixedly connected to the free end of the bimetallic strip 5.

[0026] The follower 61 is slidably mounted on the main base 1, with one end abutting against the contour surface of the cam 6. A return spring 64 is provided between the follower 61 and the main base 1. Preferably, the return spring 64 is a compression spring, with one end abutting against a boss on the follower 61 and the other end abutting against a fixed stop on the main base 1, always forcing the follower 61 to fit tightly against the contour of the cam 6, eliminating transmission backlash. The other end of the follower 61 is fixedly connected to a rack 62, which slides within a linear groove 14 on the main base 1, allowing it to move linearly only along the axial direction of the tube.

[0027] The second input gear 63 is rotatably mounted on the main base 1 via bearings and meshes with the rack 62. A sun gear 7, which is an external gear, is coaxially fixedly connected to the axle of the second input gear 63, forming another input end of the differential gear train.

[0028] In the above structure, the profile of cam 6 is constructed such that, within the entire operating temperature range sensed by bimetallic strip 5, the rotation angle of cam 6 is linearly related to the theoretical thermal elongation of the cable protection pipe at the corresponding temperature, determined by its own material linear expansion coefficient and original length. When the pipe wall temperature changes, bimetallic strip 5 drives cam 6 to rotate through an angle, and the cam push causes the follower 61 to generate displacement. This displacement is converted into the rotation angle of sun gear 7 via rack 62 and second input gear 63, and the magnitude of this rotation angle is proportional to the theoretical thermal elongation.

[0029] The sun gear 7, ring gear 8, planet carrier, and at least two planet gears together form a planetary gear differential mechanism. The planet carrier is rotatably mounted on the main base 1 via bearings. Two or three planet gears are evenly distributed around its circumference. Each planet gear is rotatably mounted on the planet carrier via a small shaft and simultaneously meshes externally with the sun gear 7 and internally with the ring gear 8. A pointer is fixedly connected to the end of the planet carrier's shaft via a set screw. The dial is fixed to the outside of the main base 1, and the indicating end of the pointer sweeps across the surface of the dial. The dial is divided into a green safety zone and a red alarm zone.

[0030] The method of using (working principle) of this invention is as follows: When installing this device, first clamp the main base 1 onto the protective tube, then fix the baffle 2 in the appropriate position with a clamp, so that the ball head 33 contacts the end face of the baffle 2, and pre-press it a certain distance to ensure that the pointer indicates the starting section of the green safety zone when cold.

[0031] As the cable and ambient temperature change slowly, the temperature of the protective tube wall rises and falls accordingly. On one hand, the baffle 2 undergoes actual axial displacement with the tube body, pushing the measuring rod 3. After being amplified by the connecting rod 31 and the sector gear 32, it causes the first input gear 4 and the gear ring 8 to rotate through a certain angle. On the other hand, the bimetallic strip 5 senses the same tube wall temperature and, through the cam 6, follower 61, rack 62, and second input gear 63, causes the sun gear 7 to rotate through an angle representing the theoretical thermal expansion. Due to the linear design of the cam profile, input A and input B are completely synchronized and proportional during normal thermal expansion and contraction. That is, the gear ring 8 and the sun gear 7 rotate in the same direction and at the same speed. At this time, the planetary gears only rotate on their own axis and do not drive the planet carrier to revolve. The pointer remains stationary and is always within the green safe zone.

[0032] When abnormally high temperatures are generated inside the cable due to overload, short circuit, or other faults, causing a rapid axial thermal thrust that exceeds normal thermal equilibrium, the actual axial elongation of the pipe will be significantly greater than the theoretical elongation that should occur solely due to the instantaneous temperature of the pipe wall. At this time, the actual displacement input A transmitted by measuring rod 3 suddenly increases, while the theoretical displacement input B reflected by bimetallic strip 5 remains lagging or small. An angular difference appears between the two inputs. This difference, through the differential action of the planetary gears, drives the planetary carrier to rotate, thereby causing the pointer to deflect significantly, instantly moving from the green safe zone to the red alarm zone, achieving a direct over-limit alarm. The alarm status can be directly observed by inspection personnel. Even if the temperature drops after the fault is cleared, if the pipe has undergone irreversible deformation, the pointer will remain in the alarm zone, serving as a memory function.

[0033] This device requires no power supply, wires, or any electronic components throughout the entire process. It has a simple and reliable structure and realizes online monitoring of thermal deformation of cable protection pipes, automatic temperature compensation, and purely mechanical alarm. It has significant advantages such as intrinsic safety, long life and maintenance-free operation.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An apparatus for on-line monitoring of the hot deformation temperature of a cable protection pipe, characterized in that: The system includes a main base (1) on which a fixing mechanism (11) is provided. The main base (1) is also provided with a guide hole (13) and a straight groove (14). A baffle (2) is fixedly clamped on the cable protection pipe. A measuring rod (3) is slidably inserted in the guide hole (13). A ball head (33) is fixed at the first end of the measuring rod (3). The ball head (33) abuts against the end face of the baffle (2). A connecting rod (31) is movably connected to the main base (1). The connecting rod (31) is hinged to the main base (1) in the middle. The first end of the connecting rod (31) is movably connected to the second end of the measuring rod (3). A sector gear (32) is fixed at the second end of the connecting rod (31). It also includes a first input gear (4), a second input gear (63), a bimetallic strip (5), a disc cam (6), and a follower (61); the first input gear (4) is rotatably mounted on the main base (1) and meshes with the sector gear (32), and a gear ring (8) is coaxially fixed on the axle of the first input gear (4); the bimetallic strip (5) is helical, with its helical center end fixed to the main base (1), and its helical outer end serving as a free end against the outer wall of the cable protection pipe; the disc cam (6) is fixedly connected to... The free end of the bimetallic strip (5); the follower (61) is slidably disposed on the main base (1), one end of the follower (61) abuts against the contour surface of the cam (6), and the other end of the follower (61) is fixedly connected to a rack (62); the rack (62) is slidably engaged in the linear groove (14); the second input gear (63) is rotatably mounted on the main base (1) and meshes with the rack (62), and a sun gear (7) is coaxially fixed on the axle of the second input gear (63).

2. The apparatus according to claim 1, characterized in that: It also includes a planetary carrier, a pointer, and a dial; the planetary carrier is rotatably mounted on the main base (1), and at least two planetary gears are evenly distributed around the planetary carrier. Each planetary gear is rotatably mounted on the planetary carrier and simultaneously meshes with the sun gear (7) and the gear ring (8); the pointer is fixedly connected to the shaft end of the planetary carrier. The dial is fixed to the main base (1), and the pointer sweeps across the surface of the dial. The dial is divided into a green safety area and a red alarm area.

3. The online monitoring device for thermal deformation temperature of cable protection pipe according to claim 1, characterized in that: The measuring rod (3) is made of Invar alloy, the baffle (2) is made of wear-resistant material, the main base (1) is a rigid frame, and the baffle (2) and the main base (1) maintain an initial distance.

4. The apparatus according to claim 1, characterized in that: An elastic copper sheet (51) is fixedly connected to the free end of the bimetallic strip (5). The elastic copper sheet (51) is attached to the outer wall of the cable protection tube. A return spring (64) is provided between the driven member (61) and the main base (1) to force the driven member (61) to be in close contact with the cam (6).

5. The apparatus according to claim 1, characterized in that: The profile of the cam (6) is configured such that, within the operating temperature range sensed by the bimetallic strip (5), the rotation angle of the cam (6) is linearly related to the theoretical thermal elongation determined by the thermal expansion coefficient of the cable protection pipe material itself.

6. The apparatus according to claim 1, characterized in that: The baffle (2) is fixedly clamped to the cable protection pipe by a clamp (21).

7. The apparatus according to claim 1, characterized in that: The distance from the middle hinge point of the link (31) to its first end is less than the distance to its second end.

8. The on-line monitoring device for thermal deformation temperature of cable protection tube according to claim 2, characterized in that: The number of planetary gears circumferentially distributed on the planet carrier is two or three.

9. The apparatus according to claim 1, characterized in that: The reset spring (64) is a compression spring, with one end abutting against the driven member (61) and the other end abutting against the main base (1).

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