Research on Traction Speed Regulation and Braking Device of Pipeline Intelligent Plugging Robot

ObjectiveWith increasing pipeline mileage and service time, more pipelines are being damaged due to environmental corrosion and human factors. This damage results in interruptions in transport and leakage of oil and gas, which in turn causes economic losses, environmental pollution, ecological damage, and other safety issues. To quickly address pipeline breakage during oil and gas transportation and to plug pipelines without halting transmission, pipeline intelligent plugging robots must be capable of rapidly and accurately reaching the damaged section and achieving maximum deceleration.MethodsTo this end, a DC cut-off valve-type traction speed regulation and braking device for a pipeline intelligent plugging robot is designed. Based on the in-pipe motion model of the robot and analysis of the speed regulation mechanism, a motion mechanism model incorporating the traction speed regulation and braking device is established. Its motion influencing factors are analyzed to determine key parameters affecting speed control characteristics. Using finite element numerical simulation, the speed valve’s flow field characteristics are analyzed, examining how the valve seat’s axial length, drain length, and internal diameter affect pressure drop. The influence of each parameter on flow and pressure drop is determined to optimize the design. Simulations of the crude oil pipeline plugging robot's motion mechanism are carried out under actual working conditions to identify performance-related factors. Proportional scaling test devices are fabricated for crude oil and refined oil pipeline conditions. Using a power torque system to supply liquid, throttling pressure drop experiments are conducted. Pressure values at varying valve openings are measured to verify the structural design’s reliability and effectiveness.Results and DiscussionsThe results show that the traction speed control and braking device’s performance is strongly affected by the structure and shape of the speed control valve. Six different axial elongation values for the valve seat—0.10<italic>D</italic>, 0.15<italic>D</italic>, 0.20<italic>D</italic>, 0.25<italic>D</italic>, 0.30<italic>D</italic>, and 0.35<italic>D </italic>(<italic>D</italic> is the inner diameter of the pipe)—significantly influence pressure drop. As the elongation increases, pressure loss decreases. Likewise, five drain hole lengths—0.80<italic>Z</italic>, 0.75<italic>Z</italic>, 0.70<italic>Z</italic>, 0.65<italic>Z</italic>, and 0.60<italic>Z </italic>(<italic>Z</italic> is the speed control valve axial length)—exert a significant effect on pressure drop across the device. Longer drain holes lead to lower pressure differentials. In contrast, five inner diameters of the valve seat—<italic>Φ</italic>169.7 mm, <italic>Φ</italic>179.7 mm, <italic>Φ</italic>189.7 mm, <italic>Φ</italic>199.7 mm, and <italic>Φ</italic>209.7 mm—have a relatively minor effect on pressure drop. After comprehensive analysis, the optimal structural parameters are determined: an axial elongation of 96.7 mm, an inner diameter of 169.7 mm, and a drain hole length of 92.8 mm. This combination yields a pressure loss of 0.139 MPa. As the valve opening decreases, the flow rate and velocity at the device outlet increase. Turbulence intensity also rises, peaking at an opening of 0.4, where high-speed water jets strike the pipeline's inner wall, effectively removing debris and preventing downstream clogging. This also reduces drag on the robot. Conversely, at full opening (1.0), the pressure differential is minimal, enabling the maximum deceleration effect. The study confirms that the designed device enables the robot to achieve efficient pipeline flushing, maintain effective speed regulation, and attain maximum deceleration, thereby fulfilling the plugging task.ConclusionsThis study provides a theoretical foundation for the structural design and parameter selection of intelligent pipeline plugging robots. It also offers valuable data and design guidance for fluid-driven pipeline robots equipped with bypass rotary valves.