A highly reliable rear-tipping rocket pendulum hydraulic system and control method

Abstract

The present invention relates to a highly reliable rear-inverted rocket pendulum hydraulic system. A gear is fixed on the rotating shaft of the rocket pendulum mechanism. The input ends of the main gear pump and the auxiliary gear pump of the hydraulic control system are both connected to the fuel tank. The output ends of the main gear pump and the auxiliary gear pump are both connected to the input end of the flow control element. The output end of the flow control element is respectively connected to the oil supply input ends of the main direction control element and the auxiliary direction control element. The oil supply output ends of the main direction control element and the auxiliary direction control element are both connected to the rodless cavity of the pendulum cylinder. The rodless cavity of the pendulum cylinder is respectively connected to the oil return input ends of the main direction control element and the auxiliary direction control element. The oil return output ends of the main direction control element and the auxiliary direction control element are connected to the fuel tank. The rack on the piston rod of the pendulum cylinder meshes with the gear. The present invention can ensure the smoothness of swinging under variable loads, high wind loads and large inertia, avoid abnormal conditions such as stalling and jitter during swinging, and ensure the reliability of swinging open before launch.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic control, and particularly to a highly reliable hydraulic system and control method for a rearward-tilting rocket swing bar. Background Art

[0002] The swing bar system is an important component in the rocket launch support system, which is used to provide support and fixation for equipment such as liquid oxygen filling and draining connectors and their filling pipelines, filling liquid level transducers and their connecting cables, etc. After the cable plugs and connectors are detached before launch, it swings them to a safe range to create a safe passage for the rocket to take off.

[0003] At present, there are two layout methods for the swing bars supporting the Long March series rockets, which are respectively arranged on the launch tower and the umbilical tower, both adopting the horizontal swing method. During the swing, it is basically not affected by gravity. In addition, the horizontal swing angle is relatively large (generally greater than 76°), and the sway amount when the swing bar reaches the position during the pre-launch swing does not affect the take-off channel.

[0004] The swing bar of the new rocket launch pad adopts the vertical swing method, which is completely different from the previous swing bar layout method and swing method. After the rocket is hoisted, the swing bar needs to swing back from the swung-open position to the -6° rocket-holding position (taking the vertical state of the swing bar, i.e., 90°, as 0°, and based on this, the angle of the swing bar holding the rocket forward is negative, and the angle of the swing bar swinging backward is positive). The swing bar has a large mass and a long length, which is a large-inertia load for the drive system, and its stability is more difficult to control than that of general loads. Since the swing bar is relatively close to the rocket at this time, it is necessary to strictly control the sway amount when it swings back to the position to prevent the swing bar from swaying and hitting the rocket. After the rocket is filled with fuel until just before take-off, the swing bar needs to be held at the rocket-holding position for a long time under the action of wind load. And just before take-off, the swing bar needs to swing backward vertically by 30° within 30 s to clear the rocket take-off channel. Since the swing angle is relatively small, the reliability requirement for its swing is higher than before. The swing bar crosses the centroid position during the swing process, and the load changes from a positive load to a negative load. Moreover, the swing bar is located in a windy area and is affected by multiple factors such as variable wind load, variable load, and its own large inertia during the swing process, and its stability control is relatively complex. Summary of the Invention

[0005] The present invention innovatively provides a highly reliable hydraulic system and control method for a rearward-tilting rocket swing bar. The present invention can ensure the stability of the swing under variable load, high wind load, and large inertia, avoid abnormal conditions such as stall and jitter during the swing, and ensure the reliability of the pre-launch swing.

[0006] To solve the above problems existing in the prior art, a highly reliable rear-inverting rocket pendulum hydraulic system provided by the present invention includes a rocket pendulum mechanism and a hydraulic control system. The rocket pendulum mechanism includes a mounting frame, a rotating shaft, and a pendulum rod. The rotating shaft is rotatably mounted on the mounting frame. The lower end of the pendulum rod is fixed to the middle of the rotating shaft. One end of the rotating shaft passes through the mounting frame, and a gear is fixed on the part of the rotating shaft passing through the mounting frame. The hydraulic control system includes an oil tank, a main gear pump, an auxiliary gear pump, a flow control element, a main direction control element, an auxiliary direction control element, and a pendulum rod hydraulic cylinder. The input ends of the main gear pump and the auxiliary gear pump are both connected to the oil tank. The output ends of the main gear pump and the auxiliary gear pump are both connected to the input end of the flow control element through an oil delivery pipe. The output end of the flow control element is respectively connected to the oil delivery input ends of the main direction control element and the auxiliary direction control element. The oil delivery output ends of the main direction control element and the auxiliary direction control element are both connected to the rodless cavity of the pendulum rod hydraulic cylinder through a first branch oil pipe. The rodless cavity of the pendulum rod hydraulic cylinder is respectively connected to the oil return input ends of the main direction control element and the auxiliary direction control element through a second branch oil pipe. The oil return output ends of the main direction control element and the auxiliary direction control element are connected to the oil tank through an oil return pipe. A rack is fixed on the piston rod of the pendulum rod hydraulic cylinder, and the rack meshes with the gear.

[0007] Further, in a highly reliable rear-inverting rocket pendulum hydraulic system of the present invention, the flow control element includes a third branch oil pipe, a slow speed regulating valve, a stop valve, a fast speed regulating valve, and a first electromagnetic reversing valve. The slow speed regulating valve is installed on the oil delivery pipe. The stop valve, the fast speed regulating valve, and the first electromagnetic reversing valve are installed on the third branch oil pipe, and the fast speed regulating valve is arranged between the stop valve and the first electromagnetic reversing valve. One end of the third branch oil pipe is connected to the oil delivery pipe at the input end of the slow speed regulating valve, and the other end of the third branch oil pipe is connected to the oil delivery pipe at the output end of the slow speed regulating valve. The stop valve is located at one end of the third branch oil pipe, and the first electromagnetic reversing valve is located at the other end of the third branch oil pipe.

[0008] Further, in a highly reliable rear-inverting rocket pendulum hydraulic system of the present invention, the main direction control element includes a first balance valve, a second balance valve, and a second electromagnetic reversing valve. The first balance valve is arranged on the first branch oil pipe. The second balance valve is arranged on the second branch oil pipe. The hydraulic control port of the first balance valve is connected to the second branch oil pipe at the liquid inlet of the second balance valve. The hydraulic control port of the second balance valve is connected to the first branch oil pipe at the liquid inlet of the first balance valve. The second electromagnetic reversing valve is a three-position four-way electromagnetic reversing valve. The P port of the second electromagnetic reversing valve is connected to the oil delivery pipe at the output end of the slow speed regulating valve. The A port of the second electromagnetic reversing valve is connected to the liquid inlet of the first balance valve. The B port of the second electromagnetic reversing valve is connected to the liquid inlet of the second balance valve. The T port of the second electromagnetic reversing valve is connected to the oil return pipe.

[0009] Further, for a highly reliable rear - inverted rocket swing bar hydraulic system of the present invention, the auxiliary direction control elements include a third balance valve, a fourth balance valve, and a third electromagnetic reversing valve. The third electromagnetic reversing valve is a three - position four - way electromagnetic reversing valve. The liquid inlet of the third balance valve is connected to port A of the third electromagnetic reversing valve through a fourth oil pipe. The liquid outlet of the third balance valve is connected to the first oil pipe at the rodless cavity of the swing bar hydraulic cylinder through a fifth oil pipe. The liquid inlet of the fourth balance valve is connected to port B of the third balance valve through a sixth oil pipe. The liquid outlet of the fourth balance valve is connected to the second oil pipe at the rod - end cavity of the swing bar hydraulic cylinder through a seventh oil pipe. The hydraulic control port of the third balance valve is connected to the sixth oil pipe. The hydraulic control port of the fourth balance valve is connected to the fourth oil pipe. The P port of the third electromagnetic reversing valve is connected to the oil supply pipe at the P port of the second electromagnetic reversing valve through an eighth oil pipe. The T port of the third electromagnetic reversing valve is connected to the oil return pipe through a ninth oil pipe.

[0010] Further, for a highly reliable rear - inverted rocket swing bar hydraulic system of the present invention, a fourth electromagnetic reversing valve is installed on the first oil pipe between the first balance valve and the fifth oil pipe, and a fifth electromagnetic reversing valve is installed on the second oil pipe between the second balance valve and the seventh oil pipe.

[0011] Further, for a highly reliable rear - inverted rocket swing bar hydraulic system of the present invention, the output end of the main gear pump is connected to the oil supply pipe through a tenth oil pipe. A first oil filter and a first one - way valve are arranged in sequence on the tenth oil pipe according to the flow direction of the hydraulic oil. The output end of the auxiliary gear pump is connected to the oil supply pipe through an eleventh oil pipe. A second oil filter and a second one - way valve are arranged in sequence on the eleventh oil pipe according to the flow direction of the hydraulic oil.

[0012] Further, for a highly reliable rear - inverted rocket swing bar hydraulic system of the present invention, one ends of a twelfth oil pipe and a thirteenth oil pipe are respectively connected to the tenth oil pipe between the first oil filter and the first one - way valve, and the other ends of the twelfth oil pipe and the thirteenth oil pipe are both connected to the oil return pipe. A first overflow valve is arranged on the twelfth oil pipe, and a sixth electromagnetic reversing valve is arranged on the thirteenth oil pipe. One ends of a fourteenth oil pipe and a fifteenth oil pipe are respectively connected to the eleventh oil pipe between the second oil filter and the second one - way valve, and the other ends of the fourteenth oil pipe and the fifteenth oil pipe are both connected to the oil return pipe. A second overflow valve is arranged on the fourteenth oil pipe, and a seventh electromagnetic reversing valve is arranged on the fifteenth oil pipe.

[0013] Further, for a highly reliable rear - tilting rocket pendulum hydraulic system of the present invention, an air cooler, a third one - way valve, and an oil return filter are sequentially arranged on the oil return pipe according to the flow direction of the hydraulic oil. The air cooler is arranged in parallel with the third one - way valve. A displacement sensor is arranged inside the pendulum hydraulic cylinder. A first pressure sensor is arranged on the seventh oil pipe. A second pressure sensor and a mechanical pressure gauge are respectively arranged on the eleventh oil pipe. A third pressure sensor is arranged on the oil supply pipe.

[0014] Further, for a highly reliable rear - tilting rocket pendulum hydraulic system of the present invention, the swing angle range of the pendulum is from - 6° to 24°. A first travel switch and a second travel switch are respectively arranged at the position where the swing angle of the pendulum is - 6°. A third travel switch is arranged at the position where the swing angle of the pendulum is - 3°. A fourth travel switch is arranged at the position where the swing angle of the pendulum is 22°. A fifth travel switch and a sixth travel switch are respectively arranged at the position where the swing angle of the pendulum is 24°.

[0015] The present invention also provides a control method for the above - mentioned highly reliable rear - tilting rocket pendulum hydraulic system.

[0016] It includes a step of swinging the pendulum open and a step of swinging the pendulum back.

[0017] The step of swinging the pendulum open includes:

[0018] Electromagnetic coils YA1 of the sixth electromagnetic directional valve and YA2 of the seventh electromagnetic directional valve are respectively energized to open the sixth electromagnetic directional valve and the seventh electromagnetic directional valve, and then the stop valve is opened.

[0019] The main gear pump and the auxiliary gear pump are started. The main gear pump and the auxiliary gear pump are started under unloading. After the main gear pump and the auxiliary gear pump run smoothly, the electromagnetic coil YA1 of the sixth electromagnetic directional valve is de - energized to close the sixth electromagnetic directional valve. Then the main gear pump builds pressure to work, and the auxiliary gear pump keeps running under unloading.

[0020] The electromagnetic coil YA3 of the first electromagnetic directional valve is energized to close the quick speed - regulating valve.

[0021] The electromagnetic coil YA4b of the second electromagnetic directional valve is energized to commutate, so that the hydraulic oil passes through the slow speed - regulating valve. A small part of the hydraulic oil leads to the hydraulic control port of the second balance valve to open the second balance valve. The rest of the hydraulic oil enters the rodless cavity of the pendulum hydraulic cylinder through the second electromagnetic directional valve and the one - way oil passage of the first balance valve, driving the piston rod of the pendulum hydraulic cylinder to extend and pushing the rack to extend. Then the rack drives the pendulum to tilt backward and swing open.

[0022] When the swing angle of the swing rod reaches -3°, cut off the power supply of the electromagnetic coil YA3 of the first electromagnetic directional valve to open the first electromagnetic directional valve, and then open the quick speed regulating valve, so that the quick speed regulating valve and the slow speed regulating valve are opened simultaneously, and the swing rod swings open quickly;

[0023] When the swing angle of the swing rod reaches 22°, energize the electromagnetic coil YA3 of the first electromagnetic directional valve to close the first electromagnetic directional valve, and then close the quick speed regulating valve, so that the quick speed regulating valve is closed and the slow speed regulating valve is opened, and the swing rod swings open slowly;

[0024] When the swing angle of the swing rod reaches 24°, the main gear pump stops working;

[0025] If the swing rod does not swing to -3° within a certain period of time, cut off the power supply of the electromagnetic coil YA2 of the seventh electromagnetic directional valve to close the seventh electromagnetic directional valve, and the auxiliary gear pump immediately builds pressure;

[0026] Energize the electromagnetic coil YA6 of the fourth electromagnetic directional valve and the electromagnetic coil YA7 of the fifth electromagnetic directional valve to close the fourth electromagnetic directional valve and the fifth electromagnetic directional valve, and energize the electromagnetic coil YA5b of the third electromagnetic directional valve, so that the port A and port P of the third electromagnetic directional valve are conducted, and the port B and port T are conducted, and the backup circuit works to execute the step of swinging the swing rod open;

[0027] The step of swinging the swing rod back includes:

[0028] Close the stop valve, and the main gear pump builds pressure;

[0029] Energize the electromagnetic coil YA3 of the first electromagnetic directional valve to close the quick speed regulating valve 20;

[0030] Energize and reverse the electromagnetic coil YA4a of the second electromagnetic directional valve, so that the port A and port T of the second electromagnetic directional valve are conducted, and the port B and port P are conducted. The hydraulic oil passes through the slow speed regulating valve, a small part of the hydraulic oil leads to the hydraulic control port of the first chamber balance valve to open the first balance valve, and the rest of the hydraulic oil enters the rod chamber of the swing rod hydraulic cylinder through the second electromagnetic directional valve and the one-way oil passage of the second balance valve, driving the piston rod of the swing rod hydraulic cylinder to retract and pulling the rack to retract, and then the rack drives the swing rod to swing back;

[0031] When the swing angle of the swing rod reaches -6°, the main gear pump 6 stops working;

[0032] If the swing-back of the swing rod fails, energize the electromagnetic coil YA6 of the fourth electromagnetic directional valve and the electromagnetic coil YA7 of the fifth electromagnetic directional valve to close the fourth electromagnetic directional valve and the fifth electromagnetic directional valve, and energize the electromagnetic coil YA5a of the third electromagnetic directional valve to make the port A and port T of the third electromagnetic directional valve conducted, and the port B and port P are conducted, and the backup circuit works to execute the step of swinging the swing rod back.

[0033] Compared with the prior art, a highly reliable rear - tilting rocket swing - rod hydraulic system of the present invention has the following advantages: In the present invention, the piston rod of the swing - rod hydraulic cylinder is directly connected to the rack, and the rack drives the gear on the rotating shaft to rotate, thereby driving the swing - rod fixed on the rotating shaft to swing. When the piston rod of the swing - rod hydraulic cylinder extends, the swing - rod tilts backward; when the piston rod fully extends, the swing - rod is in the fully - opened position. When the piston rod of the swing - rod hydraulic cylinder retracts, when the piston rod fully retracts, the swing - rod just reaches the arrow - holding position. In the hydraulic control system, a main gear pump and an auxiliary gear pump, as well as a main direction control element and an auxiliary direction control element, are provided. The two are redundant backups to ensure the high reliability of the overall system. This enables the present invention to ensure the smoothness of swinging under variable loads, high wind loads, and large inertia, avoiding abnormal conditions such as stalling and jitter during swinging, so as to ensure the reliability of the pre - launch swing - opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the principle of the hydraulic control system in a highly reliable rear - tilting rocket swing - rod hydraulic system of the present invention;

[0035] Figure 2 It is a schematic structural diagram of a highly reliable rear - tilting rocket swing - rod hydraulic system of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0037] A highly reliable rear - tilting rocket swing - rod hydraulic system of the present invention specifically includes a rocket swing - rod mechanism and a hydraulic control system. As Figure 2 shown, the rocket swing - rod mechanism specifically includes a mounting bracket 1, a rotating shaft 2, and a swing - rod 3. The rotating shaft 2 is rotatably installed on the mounting bracket 1. The lower end of the swing - rod 3 is fixed in the middle of the rotating shaft 2. One end of the rotating shaft 2 passes through the mounting bracket 1, and a gear 4 is fixed on the part of the rotating shaft 2 that passes through the mounting bracket 1. When the rotating shaft 2 rotates, the swing - rod 3 swings. As Figure 1As shown, the hydraulic control system specifically includes an oil tank 5, a main gear pump 6, an auxiliary gear pump 7, a flow control element 8, a main direction control element 9, an auxiliary direction control element 10 and a rocker arm hydraulic cylinder 11. The input ends of the main gear pump 6 and the auxiliary gear pump 7 are connected to the oil tank 5, and the output ends of the main gear pump 6 and the auxiliary gear pump 7 are connected to the input end of the flow control element 8 through the oil delivery pipe 12, and the output end of the flow control element 8 is respectively connected to the oil delivery input ends of the main direction control element 9 and the auxiliary direction control element 10, and the oil delivery output ends of the main direction control element 9 and the auxiliary direction control element 10 are connected to the rodless cavity of the rocker hydraulic cylinder 11 through the first branch oil pipe 13, and the rodless cavity of the rocker hydraulic cylinder 11 is respectively connected to the return oil input ends of the main direction control element 9 and the auxiliary direction control element 10 through the second branch oil pipe 14, and the return oil output ends of the main direction control element 9 and the auxiliary direction control element 10 are connected to the oil tank 5 through the return oil pipe 15, and finally a hydraulic circuit is formed, and a rack 16 is fixed on the piston rod of the rocker hydraulic cylinder 11, so that the rack 16 is meshed with the gear 4. When the piston rod of the rocker arm hydraulic cylinder 11 is extended, the rocker arm 3 is swung back and forth, and when the piston rod is fully extended, the rocker arm 3 is swung into place; when the piston rod of the rocker arm hydraulic cylinder 11 is retracted, the rocker arm 3 swings toward the rocket, and when the piston rod is fully retracted, the rocker arm 3 just reaches the arrow-holding position.

[0038] In this embodiment, the main gear pump 6 and the auxiliary gear pump 7 are mutually redundant backups. When working, the main gear pump 6 works to increase pressure, and the auxiliary gear pump 7 waits for unloading. If the working circuit of the main gear pump 6 fails, the auxiliary gear pump 7 builds pressure to work and replaces the main gear pump 6; the main direction control element 9 and the auxiliary direction control element 10 are mutually redundant backups. When working, the main direction control element 9 controls the swing arm hydraulic cylinder 11 to extend or retract. When the main direction control element 9 fails, the auxiliary direction control element 10 replaces the main direction control element to work, thereby ensuring stable and reliable operation of the system. The flow control element 8 can realize the functions of fast swinging, slow swinging back and slow opening and closing at a small angle. It has the functions of slow starting and slow stopping when swinging quickly, reducing the shaking amount when holding the arrow. The use of hydraulic drive can ensure the stability of the swing arm 3 under variable load, high wind load and large inertia, and realize the upper time (>6h) of the swing arm hydraulic cylinder 11 under wind load, so that the swing arm 3 can maintain a completely closed state of holding the arrow, ensuring the stability of the rocket before launching.

[0039] On the basis of the above embodiments, the flow control element 8 in this embodiment specifically includes a third branch oil pipe 17, a slow speed regulating valve 18, a stop valve 19, a fast speed regulating valve 20, and a first electromagnetic reversing valve 21. Among them, the slow speed regulating valve 18 is installed on the oil delivery pipe 12, and the stop valve 19, the fast speed regulating valve 20, and the first electromagnetic reversing valve 21 are installed on the third branch oil pipe 17, and the fast speed regulating valve 20 is arranged between the stop valve 19 and the first electromagnetic reversing valve 21. One end of the third branch oil pipe 17 is communicated with the oil delivery pipe 12 at the input end of the slow speed regulating valve 18, and the other end of the third branch oil pipe 17 is communicated with the oil delivery pipe 12 at the output end of the slow speed regulating valve 18. The stop valve 19 is located at one end of the third branch oil pipe 17, and the first electromagnetic reversing valve 21 is located at the other end of the third branch oil pipe 17. More specifically, both the slow speed regulating valve 18 and the fast speed regulating valve 20 are overflow valves, and the difference between them is that the opening pressure of the slow speed regulating valve 18 is higher than that of the fast speed regulating valve 20, and the slow speed regulating valve 18 and the fast speed regulating valve 20 are arranged in parallel. The stop valve 19 is a stop valve with a limit switch, and the stop valve 19 is used to manually switch the fast and slow speeds of the swing rod hydraulic cylinder 11. The first electromagnetic reversing valve 21 is preferably a normally open two-position two-way electromagnetic reversing valve. The stop valve 19 and the first electromagnetic reversing valve 21 are redundant to each other, and their functions are to control whether the third oil pipe 17 where the fast speed regulating valve 20 is located is put into operation. If either of them is closed, the fast speed regulating valve is closed, and the swing rod hydraulic cylinder can only move slowly. In this embodiment, the control effect of speed grading can be realized. When only the slow speed regulating valve 18 is supplied with oil, the swing rod hydraulic cylinder 11 moves slowly. When both the slow speed regulating valve 18 and the fast speed regulating valve 20 are supplied with oil, the swing rod hydraulic cylinder 11 moves quickly.

[0040] Based on the above embodiments, the main direction control element 9 in this embodiment includes a first balance valve 22, a second balance valve 23, and a second electromagnetic directional control valve 24. The first balance valve 22 is arranged on the first branch oil pipe 13, and the second balance valve 23 is arranged on the second branch oil pipe 14. The hydraulic control port of the first balance valve 22 is communicated with the second branch oil pipe 14 at the liquid inlet of the second balance valve 23, and the hydraulic control port of the second balance valve 23 is communicated with the first branch oil pipe 13 at the liquid inlet of the first balance valve 22. The second electromagnetic directional control valve 24 is a three-position four-way electromagnetic directional control valve. The P port of the second electromagnetic directional control valve 24 is communicated with the oil delivery pipe 12 at the output end of the slow speed regulating valve 18. The A port of the second electromagnetic directional control valve 24 is communicated with the liquid inlet of the first balance valve 22. The B port of the second electromagnetic directional control valve 24 is communicated with the liquid inlet of the second balance valve 23. The T port of the second electromagnetic directional control valve 24 is communicated with the oil return pipe 15. Specifically, the second electromagnetic directional control valve 24 is used to control the movement direction of the swing rod hydraulic cylinder 11, and the first balance valve 22 and the second balance valve 23 are used to effectively control the variable load during the swinging process of the swing rod 3, so that the whole swinging process is stable, and the pressure change caused by the variable load can be effectively balanced. Especially during the swinging process, the center of mass will be passed, and the load changes from a positive load to a negative load. The first balance valve 22 and the second balance valve 23 can form a certain back pressure for balancing, thereby ensuring the stable operation of the system.

[0041] The auxiliary direction control element 10 specifically includes a third balance valve 25, a fourth balance valve 26, and a third electromagnetic directional control valve 27. The third electromagnetic directional control valve 27 is a three-position four-way electromagnetic directional control valve. The liquid inlet of the third balance valve 25 is communicated with the A port of the third electromagnetic directional control valve 27 through the fourth branch oil pipe 28. The liquid outlet of the third balance valve 25 is communicated with the first branch oil pipe 13 at the rodless cavity of the swing rod hydraulic cylinder 11 through the fifth branch oil pipe 29. The liquid inlet of the fourth balance valve 26 is connected to the B port of the third balance valve 25 through the sixth branch oil pipe 30. The liquid outlet of the fourth balance valve 26 is communicated with the second branch oil pipe 14 at the rod cavity of the swing rod hydraulic cylinder 11 through the seventh branch oil pipe 31. The hydraulic control port of the third balance valve 25 is communicated with the sixth branch oil pipe 30, and the hydraulic control port of the fourth balance valve 26 is communicated with the fourth branch oil pipe 28. The P port of the third electromagnetic directional control valve 27 is communicated with the oil delivery pipe 12 at the P port of the second electromagnetic directional control valve 24 through the eighth branch oil pipe 32. The T port of the third electromagnetic directional control valve 27 is communicated with the oil return pipe 15 through the ninth branch oil pipe 33. The third electromagnetic directional control valve 27 has the same function as the second electromagnetic directional control valve 24, and the third balance valve 25 and the fourth balance valve 26 have the same function as the first balance valve 22 and the second balance valve 23, which will not be elaborated here. When the main direction control element 9 fails, the auxiliary direction control element 10 replaces it to perform the work task, thereby ensuring the reliability of the system.

[0042] Based on the above embodiments, in this embodiment, a fourth electromagnetic directional valve 34 is installed on the first oil pipe 13 between the first balance valve 22 and the fifth oil pipe 29, and a fifth electromagnetic directional valve 35 is installed on the second oil pipe 14 between the second balance valve 23 and the seventh oil pipe 31. More specifically, both the fourth electromagnetic directional valve 34 and the fifth electromagnetic directional valve 35 are normally open two-position two-way electromagnetic directional valves. The fourth electromagnetic directional valve 34 and the fifth electromagnetic directional valve 35 are used to cut off the operation of the main direction control element 9 when a failure occurs in the main direction control element 9, ensuring the stable and reliable operation of the auxiliary direction control element 10.

[0043] Based on the above embodiments, in order to further ensure the reliability of the hydraulic system, in this embodiment, the output end of the main gear pump 6 is connected to the oil delivery pipe 12 through the tenth oil pipe 36, and a first oil filter 37 and a first check valve 38 are sequentially arranged on the tenth oil pipe 36 according to the flow direction of the hydraulic oil. The output end of the auxiliary gear pump 7 is connected to the oil delivery pipe 12 through the eleventh oil pipe 39, and a second oil filter 40 and a second check valve 41 are sequentially arranged on the eleventh oil pipe 39 according to the flow direction of the hydraulic oil. The first oil filter 37 and the second oil filter 40 can ensure the purity of the hydraulic oil flowing into the hydraulic system; the first check valve 38 and the second check valve 41 are used to isolate the main gear pump 6 and the auxiliary gear pump 7 to prevent the hydraulic oil from flowing back.

[0044] One ends of a twelfth oil pipe 42 and a thirteenth oil pipe 43 are respectively connected to the tenth oil pipe 36 between the first oil filter 37 and the first check valve 38, and the other ends of the twelfth oil pipe 42 and the thirteenth oil pipe 43 are both connected to the oil return pipe 15. A first overflow valve 44 is arranged on the twelfth oil pipe 42, and a sixth electromagnetic directional valve 45 is arranged on the thirteenth oil pipe 43. The first overflow valve 44 is used to limit the maximum pressure of the main gear pump 6; the sixth electromagnetic directional valve 45 is a normally closed two-position two-way electromagnetic directional valve, which is used to unload the main gear pump 6 when energized and build pressure for the main gear pump 6 when de-energized. One ends of a fourteenth oil pipe 46 and a fifteenth oil pipe 47 are respectively connected to the eleventh oil pipe 39 between the second oil filter 40 and the second check valve 41, and the other ends of the fourteenth oil pipe 46 and the fifteenth oil pipe 47 are both connected to the oil return pipe 15. A second overflow valve 48 is arranged on the fourteenth oil pipe 46, and a seventh electromagnetic directional valve 49 is arranged on the fifteenth oil pipe 47. The second overflow valve 48 is used to limit the maximum pressure of the auxiliary gear pump 7; the seventh electromagnetic directional valve 49 is a normally closed two-position two-way electromagnetic directional valve, which is used to unload the auxiliary gear pump 7 when energized and build pressure for the auxiliary gear pump 7 when de-energized.

[0045] An air cooler 50, a third one-way valve 51, and an oil return filter 52 are successively arranged on the oil return pipe 15 in the direction of the hydraulic oil flow. The air cooler 50 and the third one-way valve 51 are arranged in parallel. When the temperature of the hydraulic system is relatively high, the air cooler 50 is used to blow and dissipate heat from the hydraulic oil. The third one-way valve 51 is arranged in parallel with the air cooler 50 to prevent oil return through the third one-way valve 51 when the air cooler 50 is blocked. A displacement sensor 53 is arranged inside the swing rod hydraulic cylinder 11, and the displacement sensor 53 is used to detect the stroke of the piston rod in the swing rod hydraulic cylinder 11. A first pressure sensor 54 is arranged on the seventh oil pipe 31 to monitor the pressure in the rod chamber of the swing rod hydraulic cylinder. A second pressure sensor 55 and a mechanical pressure gauge 56 are respectively arranged on the eleventh oil pipe 39, and a third pressure sensor 57 is arranged on the oil supply pipe 12. The second pressure sensor 55 and the third pressure sensor 57 are redundant to each other and are used to monitor the working pressure of the hydraulic system. The second pressure sensor 55 and the mechanical pressure gauge 56 are redundantly arranged for a second time to improve the reliability of system monitoring.

[0046] In order to check the swinging position of the swing rod and read the acceleration position point and deceleration position point of the swing rod, the swinging angle range of the swing rod 3 is set to -6° to 24°. A first travel switch 58 and a second travel switch 59 are respectively arranged at the position where the swinging angle of the swing rod 3 is -6°. The first travel switch 58 and the second travel switch 59 are redundant to each other and are used to detect the position where the swing rod holds the arrow in place. A third travel switch 60 is arranged at the position where the swinging angle of the swing rod 3 is -3°. The third travel switch 60 is used to detect the acceleration position point of the swing rod and the switching point of the backup circuit. A fourth travel switch 61 is arranged at the position where the swinging angle of the swing rod 3 is 22°. The fourth travel switch 61 is used to detect the deceleration position point of the swing rod. A fifth travel switch 62 and a sixth travel switch 63 are respectively arranged at the position where the swinging angle of the swing rod 3 is 24°.

[0047] The present invention also provides a control method for the above-mentioned highly reliable rear-inverting rocket swing rod hydraulic system, which specifically includes a swing rod swinging-out step and a swing rod swinging-back step;

[0048] The swing rod swinging-out step includes:

[0049] Step 1: Energize the electromagnetic coil YA1 of the sixth electromagnetic directional valve 45 and the electromagnetic coil YA2 of the seventh electromagnetic directional valve 49 respectively to open the sixth electromagnetic directional valve 45 and the seventh electromagnetic directional valve 49, and then open the stop valve 19;

[0050] Step 2: Start the main gear pump 6 and the auxiliary gear pump 7, and start the main gear pump 6 and the auxiliary gear pump 7 under unloading. After the main gear pump 6 and the auxiliary gear pump 7 operate stably, de-energize the electromagnetic coil YA1 of the sixth electromagnetic directional valve 45 to close the sixth electromagnetic directional valve 45. Then the main gear pump 6 builds pressure for work, and the auxiliary gear pump 7 remains under unloading operation;

[0051] Step 3: Energize the electromagnetic coil YA3 of the first electromagnetic directional valve 21 to close the quick speed control valve 20;

[0052] Step 4: Energize and reverse the electromagnetic coil YA4b of the second electromagnetic directional valve 24, so that the hydraulic oil passes through the slow speed control valve 18. A small part of the hydraulic oil leads to the hydraulic control port of the second balance valve 23 to open the second balance valve 23, and the rest of the hydraulic oil enters the rodless cavity of the swing rod hydraulic cylinder 11 through the one-way oil passage of the second electromagnetic directional valve 24 and the first balance valve 22, driving the piston rod of the swing rod hydraulic cylinder 11 to extend and pushing the rack 16 to extend as well. Then, the rack 16 drives the swing rod 3 to swing backward and open;

[0053] Step 6: When the swing angle of the swing rod 3 reaches -3°, de-energize the electromagnetic coil YA3 of the first electromagnetic directional valve 21, open the first electromagnetic directional valve 21, and then open the quick speed control valve 20, so that the quick speed control valve 20 and the slow speed control valve 18 are opened simultaneously, and the swing rod 3 swings open quickly;

[0054] Step 7: When the swing angle of the swing rod 3 reaches 22°, energize the electromagnetic coil YA3 of the first electromagnetic directional valve 21, close the first electromagnetic directional valve 21, and then close the quick speed control valve 20, so that the quick speed control valve 20 is closed and the slow speed control valve 18 is opened, and the swing rod 3 swings open slowly;

[0055] Step 8: When the swing angle of the swing rod 3 reaches 24°, the main gear pump 6 stops working;

[0056] If the swing rod 3 does not swing to -3° within a certain period of time, de-energize the electromagnetic coil YA2 of the seventh electromagnetic directional valve 49 to close the seventh electromagnetic directional valve 49, and the auxiliary gear pump 7 immediately builds pressure;

[0057] Energize the electromagnetic coil YA6 of the fourth electromagnetic directional valve 34 and the electromagnetic coil YA7 of the fifth electromagnetic directional valve 35 to close the fourth electromagnetic directional valve 34 and the fifth electromagnetic directional valve 35. Energize the electromagnetic coil YA5b of the third electromagnetic directional valve 27, so that port A and port P of the third electromagnetic directional valve 27 are conducted, and port B and port T are conducted, and the backup circuit works to execute the swing rod opening step;

[0058] The swing rod closing step includes:

[0059] Step 9: Close the stop valve 19, and the main gear pump 6 builds pressure;

[0060] Step 10: Energize the electromagnetic coil YA3 of the first electromagnetic directional valve 21 to close the quick speed control valve 20;

[0061] Step 10: Energize and commutate the electromagnetic coil YA4a of the second electromagnetic directional valve 24, so that the A port of the second electromagnetic directional valve 24 communicates with the T port, and the B port communicates with the P port. The hydraulic oil passes through the slow speed control valve 18. A small part of the hydraulic oil leads to the hydraulic control port of the first chamber balance valve to open the first balance valve 22. The remaining hydraulic oil enters the rodless chamber of the swing rod hydraulic cylinder 11 through the one-way oil passage of the second electromagnetic directional valve 24 and the second balance valve 23, driving the piston rod of the swing rod hydraulic cylinder 11 to retract and pulling the rack 16 to retract as well. Furthermore, the rack 16 drives the swing rod 3 to swing back;

[0062] Step 11: When the swing angle of the swing rod 3 reaches -6°, the main gear pump 6 stops working;

[0063] If the swing-back of the swing rod fails, energize the electromagnetic coil YA6 of the fourth electromagnetic directional valve 34 and the electromagnetic coil YA7 of the fifth electromagnetic directional valve 35, close the fourth electromagnetic directional valve 34 and the fifth electromagnetic directional valve 35, energize the electromagnetic coil YA5a of the third electromagnetic directional valve 27, make the A port of the third electromagnetic directional valve 27 communicate with the T port, and the B port communicate with the P port. The backup circuit works and executes the swing-back step of the swing rod.

[0064] In this embodiment, the sway amount at the start and in place of the swing-out can be effectively controlled. A hierarchical oil inlet speed control scheme is designed. Small flow is used for startup from -6° to -3°, large flow is used for operation between -3° and 22°, with a fast backward movement, and then the flow is reduced to small flow to reach the position after 22°. Slow start and stop are achieved, effectively controlling the sway amount, and at the same time meeting the requirement of rapidity.

[0065] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0067] The above embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of protection requested by the present invention. Without departing from the design spirit of the present invention, various forms of deformation made by those skilled in the art according to the technical solution of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A highly reliable rear - tilting rocket swing - rod hydraulic system, characterized in that, It includes a rocket pendulum mechanism and a hydraulic control system. The rocket pendulum mechanism includes a mounting frame (1), a rotating shaft (2), and a pendulum rod (3). The rotating shaft (2) is rotatably mounted on the mounting frame (1). The lower end of the pendulum rod (3) is fixed to the middle of the rotating shaft (2). One end of the rotating shaft (2) passes through the mounting frame (1), and a gear (4) is fixed on the part of the rotating shaft (2) that passes through the mounting frame (1). The hydraulic control system includes an oil tank (5), a main gear pump (6), an auxiliary gear pump (7), a flow control element (8), a main direction control element (9), an auxiliary direction control element (10), and a pendulum rod hydraulic cylinder (11). The input ends of the main gear pump (6) and the auxiliary gear pump (7) are both connected to the oil tank (5). The output ends of the main gear pump (6) and the auxiliary gear pump (7) are both connected to the input end of the flow control element (8) through an oil delivery pipe (12). The output end of the flow control element (8) is respectively connected to the oil delivery input ends of the main direction control element (9) and the auxiliary direction control element (10). The oil delivery output ends of the main direction control element (9) and the auxiliary direction control element (10) are both connected to the rodless cavity of the pendulum rod hydraulic cylinder (11) through a first branch oil pipe (13). The rod chamber of the pendulum rod hydraulic cylinder (11) is connected to the oil return input ends of the main direction control element (9) and the auxiliary direction control element (10) respectively through a second branch oil pipe (14). The oil return output ends of the main direction control element (9) and the auxiliary direction control element (10) are connected to the oil tank (5) through an oil return pipe (15). A rack (16) is fixed on the piston rod of the pendulum rod hydraulic cylinder (11), and the rack (16) meshes with the gear (4). The flow control element (8) includes a third branch oil pipe (17), a slow speed regulating valve (18), a stop valve (19), a fast speed regulating valve (20), and a first electromagnetic reversing valve (21). The slow speed regulating valve (18) is installed on the oil delivery pipe (12). The stop valve (19), the fast speed regulating valve (20), and the first electromagnetic reversing valve (21) are installed on the third branch oil pipe (17), and the fast speed regulating valve (20) is arranged between the stop valve (19) and the first electromagnetic reversing valve (21). One end of the third branch oil pipe (17) is connected to the oil delivery pipe (12) at the input end of the slow speed regulating valve (18), and the other end of the third branch oil pipe (17) is connected to the oil delivery pipe (12) at the output end of the slow speed regulating valve (18). The stop valve (19) is located at one end of the third branch oil pipe (17), and the first electromagnetic reversing valve (21) is located at the other end of the third branch oil pipe (17). The main direction control element (9) includes a first balance valve (22), a second balance valve (23), and a second electromagnetic reversing valve (24). The first balance valve (22) is arranged on the first branch oil pipe (13). The second balance valve (23) is arranged on the second branch oil pipe (14). The hydraulic control port of the first balance valve (22) is connected to the second branch oil pipe (14) at the liquid inlet of the second balance valve (23).The hydraulic control port of the second balance valve (23) is communicated with the first branch oil pipe (13) at the oil inlet of the first balance valve (22). The second electromagnetic reversing valve (24) is a three-position four-way electromagnetic reversing valve. The P port of the second electromagnetic reversing valve (24) is communicated with the oil delivery pipe (12) at the output end of the slow speed regulating valve (18). The A port of the second electromagnetic reversing valve (24) is communicated with the oil inlet of the first balance valve (22). The B port of the second electromagnetic reversing valve (24) is communicated with the oil inlet of the second balance valve (23). The T port of the second electromagnetic reversing valve (24) is communicated with the oil return pipe (15).

2. The highly reliable rear - tilting rocket swing - rod hydraulic system according to claim 1, characterized in that, The auxiliary direction control element (10) includes a third balance valve (25), a fourth balance valve (26) and a third solenoid directional valve (27). The third solenoid directional valve (27) is a three-position four-way solenoid directional valve. The inlet port of the third balance valve (25) is communicated with the port A of the third solenoid directional valve (27) through a fourth branch oil pipe (28). The outlet port of the third balance valve (25) is communicated with the first branch oil pipe (13) at the rodless cavity of the swing rod hydraulic cylinder (11) through a fifth branch oil pipe (29). The inlet port of the fourth balance valve (26) is connected with the port B of the third balance valve (25) through a sixth branch oil pipe (30). The outlet port of the fourth balance valve (26) is communicated with the second branch oil pipe (14) at the rod cavity of the swing rod hydraulic cylinder (11) through a seventh branch oil pipe (31). The hydraulic control port of the third balance valve (25) is communicated with the sixth branch oil pipe (30). The hydraulic control port of the fourth balance valve (26) is communicated with the fourth branch oil pipe (28). The port P of the third solenoid directional valve (27) is communicated with the oil supply pipe (12) at the port P of the second solenoid directional valve (24) through an eighth branch oil pipe (32). The port T of the third solenoid directional valve (27) is communicated with the oil return pipe (15) through a ninth branch oil pipe (33).

3. The highly reliable rear - tilting rocket swing - rod hydraulic system according to claim 2, characterized in that, A fourth solenoid directional valve (34) is installed on the first branch oil pipe (13) between the first balance valve (22) and the fifth branch oil pipe (29). A fifth solenoid directional valve (35) is installed on the second branch oil pipe (14) between the second balance valve (23) and the seventh branch oil pipe (31).

4. The highly reliable rear - tilting rocket swing - rod hydraulic system according to claim 3, characterized in that, The output end of the main gear pump (6) is communicated with the oil supply pipe (12) through a tenth branch oil pipe (36). A first oil filter (37) and a first check valve (38) are arranged in sequence on the tenth branch oil pipe (36) according to the flow direction of the hydraulic oil. The output end of the auxiliary gear pump (7) is communicated with the oil supply pipe (12) through an eleventh branch oil pipe (39). A second oil filter (40) and a second check valve (41) are arranged in sequence on the eleventh branch oil pipe (39) according to the flow direction of the hydraulic oil.

5. The highly reliable rear - tilting rocket swing - rod hydraulic system according to claim 4, characterized in that, One ends of a twelfth branch oil pipe (42) and a thirteenth branch oil pipe (43) are respectively connected to the tenth branch oil pipe (36) between the first oil filter (37) and the first check valve (38). The other ends of the twelfth branch oil pipe (42) and the thirteenth branch oil pipe (43) are both connected to the oil return pipe (15). A first overflow valve (44) is arranged on the twelfth branch oil pipe (42). A sixth solenoid directional valve (45) is arranged on the thirteenth branch oil pipe (43). One ends of a fourteenth branch oil pipe (46) and a fifteenth branch oil pipe (47) are respectively connected to the eleventh branch oil pipe (39) between the second oil filter (40) and the second check valve (41). The other ends of the fourteenth branch oil pipe (46) and the fifteenth branch oil pipe (47) are both connected to the oil return pipe (15). A second overflow valve (48) is arranged on the fourteenth branch oil pipe (46). A seventh solenoid directional valve (49) is arranged on the fifteenth branch oil pipe (47).

6. The highly reliable rear - tilting rocket swing - rod hydraulic system according to claim 5, characterized in that, An air cooler (50), a third one-way valve (51) and an oil return filter (52) are successively arranged on the oil return pipe (15) along the flow direction of the hydraulic oil. The air cooler (50) is arranged in parallel with the third one-way valve (51). A displacement sensor (53) is arranged in the swing rod hydraulic cylinder (11). A first pressure sensor (54) is arranged on the seventh oil pipe (31). A second pressure sensor (55) and a mechanical pressure gauge (56) are respectively arranged on the eleventh oil pipe (39). A third pressure sensor (57) is arranged on the oil supply pipe (12).

7. The highly reliable rear - tilting rocket swing - rod hydraulic system according to claim 6, characterized in that, The swing angle range of the swing rod (3) is from -6° to 24°. A first travel switch (58) and a second travel switch (59) are arranged at the position where the swing angle of the swing rod (3) is -6°. A third travel switch (60) is arranged at the position where the swing angle of the swing rod (3) is -3°. A fourth travel switch (61) is arranged at the position where the swing angle of the swing rod (3) is 22°. A fifth travel switch (62) and a sixth travel switch (63) are arranged at the position where the swing angle of the swing rod (3) is 24°.

8. A control method for the highly reliable rear - tilting rocket swing - rod hydraulic system according to claim 7, characterized in that, The control method includes a swing rod swinging-open step and a swing rod swinging-back step; The swing rod swinging-open step includes: Electromagnetic coils YA1 of the sixth electromagnetic directional valve (45) and YA2 of the seventh electromagnetic directional valve (49) are respectively energized to open the sixth electromagnetic directional valve (45) and the seventh electromagnetic directional valve (49), and then the stop valve (19) is opened; The main gear pump (6) and the auxiliary gear pump (7) are started, and the main gear pump (6) and the auxiliary gear pump (7) are unloaded and started. After the main gear pump (6) and the auxiliary gear pump (7) run smoothly, the electromagnetic coil YA1 of the sixth electromagnetic directional valve (45) is de-energized to close the sixth electromagnetic directional valve (45). Then the main gear pump (6) builds pressure to work, and the auxiliary gear pump (7) keeps running in an unloaded state; The electromagnetic coil YA3 of the first electromagnetic directional valve (21) is energized to close the quick speed regulating valve (20); The electromagnetic coil YA4b of the second electromagnetic directional valve (24) is energized and commutated, so that the hydraulic oil passes through the slow speed regulating valve (18). A small part of the hydraulic oil leads to the hydraulic control port of the second balance valve (23) to open the second balance valve (23). The remaining hydraulic oil enters the rodless cavity of the swing rod hydraulic cylinder (11) through the one-way oil passage of the second electromagnetic directional valve (24) and the first balance valve (22), driving the piston rod of the swing rod hydraulic cylinder (11) to extend and pushing the rack (16) to extend. Then the rack (16) drives the swing rod to swing backward and open; When the swing angle of the swing rod (3) reaches -3°, the electromagnetic coil YA3 of the first electromagnetic directional valve (21) is de-energized to open the first electromagnetic directional valve (21), and then the quick speed regulating valve (20) is opened, so that the quick speed regulating valve (20) and the slow speed regulating valve (18) are opened simultaneously, and the swing rod swings open quickly; When the swing angle of the swing rod (3) reaches 22°, energize the electromagnetic coil YA3 of the first electromagnetic directional valve (21) to close the first electromagnetic directional valve (21), and then close the quick speed control valve (20), so that the quick speed control valve (20) closes and the slow speed control valve (18) opens, and the swing rod (3) swings open slowly; When the swing angle of the swing rod (3) reaches 24°, the main gear pump (6) stops working; If the swing rod (3) does not swing to -3° within a certain period of time, de-energize the electromagnetic coil YA2 of the seventh electromagnetic directional valve (49) to close the seventh electromagnetic directional valve (49), and the auxiliary gear pump (7) immediately builds pressure; Energize the electromagnetic coil YA6 of the fourth electromagnetic directional valve (34) and the electromagnetic coil YA7 of the fifth electromagnetic directional valve (35) to close the fourth electromagnetic directional valve (34) and the fifth electromagnetic directional valve (35), and energize the electromagnetic coil YA5b of the third electromagnetic directional valve (27), so that the port A and port P of the third electromagnetic directional valve (27) are conducted, and the port B and port T are conducted, and the backup circuit works to execute the swing rod opening step; The swing rod retracting step includes: Close the stop valve (19), and the main gear pump (6) builds pressure; Energize the electromagnetic coil YA3 of the first electromagnetic directional valve (21) to close the quick speed control valve (20); Energize and commutate the electromagnetic coil YA4a of the second electromagnetic directional valve (24), so that the port A and port T of the second electromagnetic directional valve (24) are conducted, and the port B and port P are conducted. The hydraulic oil passes through the slow speed control valve (18), a small part of the hydraulic oil leads to the hydraulic control port of the first balance valve (22) to open the first balance valve (22), and the rest of the hydraulic oil enters the rodless cavity of the swing rod hydraulic cylinder (11) through the one-way oil passages of the second electromagnetic directional valve (24) and the second balance valve (23), driving the piston rod of the swing rod hydraulic cylinder (11) to retract and pulling the rack (16) to retract, and then the rack (16) drives the swing rod to retract; When the swing angle of the swing rod (3) reaches -6°, the main gear pump (6) stops working; If the swing rod (3) fails to retract, energize the electromagnetic coil YA6 of the fourth electromagnetic directional valve (34) and the electromagnetic coil YA7 of the fifth electromagnetic directional valve (35) to close the fourth electromagnetic directional valve (34) and the fifth electromagnetic directional valve (35), and energize the electromagnetic coil YA5a of the third electromagnetic directional valve (27), so that the port A and port T of the third electromagnetic directional valve (27) are conducted, and the port B and port P are conducted, and the backup circuit works to execute the swing rod retracting step.

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