Anti-entanglement pump-jet propulsion device and working method

Abstract

The present invention relates to an anti-winding pump-jet propulsion device, which comprises a front free impeller, a front stator, a rotor, a rear stator and a rear free impeller in order from front to rear in the axial direction; at least one front electric cutter is fixedly arranged at the front of the front stator; at least one rear electric cutter is fixedly arranged at the rear of the rear stator; a conical duct is fixedly sleeved on the front stator, the rotor, the rear stator and the outside; the rear free impeller is located in the conical duct, or the rear free impeller is fixedly connected to a rear duct, the rear end of the rear duct is sleeved outside the conical duct, and the gap between the rear duct and the conical duct is smaller than the size of an object that may be entangled; the front free impeller is arranged inside the conical duct, or the front free impeller is fixedly connected to a front duct, the outer diameter of the front duct is less than or equal to the outer diameter of the front free impeller, and the rear end of the front duct is sleeved outside the conical duct, and the gap between the front duct and the conical duct is smaller than the size of an object that may be entangled.

Description

Technical Field

[0001] The invention relates to a ship propeller, in particular to an anti-winding pump-jet propulsion device and a working method, belonging to the technical field of ship propulsion. Background Art

[0002] When ships are sailing in fishing areas or offshore aquaculture areas, they are often entangled in ropes or nets, causing the propellers to stop rotating and requiring personnel to go into the water for repairs, which is very inconvenient.

[0003] A pump-jet propulsion system is a marine propulsion system. The outside of the propeller is a duct. Stators are set at both ends or only at one end of the duct. The blade ends of the stator are fixedly connected to the duct and cannot rotate, so they are called stators. The middle of the duct is a propeller, also called a rotor. The axis of the stator and the rotor are located on the same straight line. Conventional rotors are driven by the tail shaft of the ship passing through the center of the front stator and connected to the rotor hub. There are also rotors that use electric propulsion and are placed in the duct without a tail shaft.

[0004] The Chinese patent document with the publication date of 2020.08.25, publication number CN111572744A, and titled "A hydraulic shear device for underwater entanglement of ship pump-jet propulsion" discloses a device for breaking ropes entangled on the propeller of a pump-jet propulsion. This solution has the following shortcomings: First, this solution belongs to passive defense, not active defense. It can only react and break the propeller after it is entangled. Secondly, it fails to solve the problem of ropes entangled on the propeller when reversing. Summary of the invention

[0005] The purpose of the present invention is to provide an anti-entanglement pump-jet propulsion device and a working method, which can react before the rope approaches the propeller (i.e., rotor) in the pump-jet propulsion device, and prevent the rope from being entangled outside the propeller, so that the propeller is not entangled. At the same time, the propeller can be prevented from being entangled in both forward and reverse sailing states. The rotor mentioned below refers to the propeller in the pump-jet propulsion device.

[0006] The present invention adopts the following technical solutions:

[0007] A entanglement-proof pump-jet propulsion device, axially from front to rear, comprises a front free impeller 100, a front stator 210, a rotor 220, a rear stator 230, and a rear free impeller 300 in sequence; at least one front electric cutter 400 is fixedly arranged at the front of the front stator 210; at least one rear electric cutter 500 is fixedly arranged at the rear of the rear stator 230; the front stator 210, the rotor 220, the rear stator 230, and an externally fixed conical conduit 240 are provided; the rear free impeller 300 is located in the conical conduit 240, or the rear free impeller 300 is connected to a rear free impeller 300. The duct 340 is fixedly connected, the rear end of the rear duct 340 is sleeved outside the conical duct 240, and the gap between the rear duct 340 and the conical duct 240 is smaller than the size of the object that may be entangled; the front free impeller 100 is arranged inside the conical duct 240, or the front free impeller 100 is fixedly connected to a front duct 140, the inner diameter of the front duct 140 is smaller than or equal to the outer diameter of the front free impeller 100, and the rear end of the front duct 140 is sleeved outside the conical duct 240, and the gap between the rear duct 140 and the conical duct 240 is smaller than the size of the object that may be entangled.

[0008] Preferably, the front blades 110 of the front free impeller 100 are connected to the front impeller hub 120 and are evenly distributed radially along the circumference of the front impeller hub 120. The front impeller hub 120 is fixed to the outer ring of the front rolling bearing 130. The inner ring of the front rolling bearing 130 is fixed to the front sleeve 150. The front sleeve 150 is fixed to the tail shaft sleeve 910 connected to the hull 900 by welding or fasteners; the front stator 210 of the pump-jet propeller 200 is sleeved on the tail shaft sleeve 910, the rotor 220 of the pump-jet propeller 200 is connected to the tail shaft 920 extending out of the tail shaft sleeve 910, and the conical duct 240 is connected to the hull 900 through the bracket 930; the rear blades 310 of the rear free impeller 300 are connected to the rear impeller hub 320 and are evenly distributed radially along the circumference of the rear impeller hub 120. The hub 320 is evenly distributed in a radial manner in the circumferential direction. The rear impeller hub 320 is fixed on the outer ring of the rear rolling bearing 330. The inner ring of the rear rolling bearing 330 is fixed on the rear sleeve 350. The rear sleeve 350 is fixed to the shaft of the rear stator 230 by welding or fasteners. No less than two front electric cutters 400 are evenly fixed on the hub of the front stator 210, and are located in front of the front stator 210, opposite to the front free impeller 100, and the axis of the front electric cutter 400 is parallel to the axis of the tail shaft sleeve 910. No less than two rear electric cutters 500 are evenly fixed on the shaft of the rear stator 230, and are located behind the rear stator 230, opposite to the rear free impeller 300, and the axis of the rear electric cutter 500 is parallel to the axis of the rear stator 230.

[0009] Furthermore, the front duct internal blades 141 are uniformly arranged in a concentric shape along the inner circumference of the front duct 140. The front duct internal blades 141 and the front blades 110 located in the duct 140 not only have the same blade section, but also have the same blade twisting direction. However, the length of the front duct internal blades 141 does not reach the front impeller hub 120. The rear part of the front duct 140 can shield the front part of the conical duct 240 to prevent the rope from flowing into the gap between the front free impeller 100 and the front stator 210. The rear part of the front duct 140 is uniformly arranged in a concentric shape along the inner circumference of the rear duct 340. The rear duct inner blade 311 is arranged in a heart shape, and the rear duct inner blade 311 has not only the same blade section as the rear blade 310, but also the same blade torsion direction, but the length of the rear duct inner blade 311 does not reach the rear impeller hub 320; when the rear duct 340 is arranged, the front part of the rear duct (340) can shield the rear part of the conical duct (240) to prevent the rope from flowing into the gap between the rear free impeller 300 and the rear stator 230; when the rear duct 340 is not arranged, the rear free impeller 300 is inside the conical duct 240.

[0010] Furthermore, the front blades 110 of the front free impeller 100 are divided into two parts: a central blade 111 and an outer blade 112; the diameter of the entire front blade 110 is 0.95-1.5 times the diameter of the front stator 210; the outer blade 112 adopts a marine propeller propeller blade, or a turbine blade that is a natural extension of the central blade 111.

[0011] Furthermore, when the front blade 110 is an integrated type: the front duct 140 is fixedly arranged on the outer edge of the front blade 110; when the front blade 110 is a split type: the front duct 140 is arranged on the top edge of the central blade 111, and the outer blades 112 are evenly and radially arranged along the outer circumference of the front duct 140. At this time, the number of blades of the central blade 111 and the outer blade 112 can be the same or different; the front duct 140 is supported by the top edge of the central blade 111 accommodated therein.

[0012] Furthermore, when the front duct 140 is provided, the rear portion of the front duct 140 can shield the front portion of the conical duct 240 to which the pump-jet propulsor 200 belongs; when the front duct 140 is not provided, the front free impeller 100 is placed inside the conical duct 240 to which the pump-jet propulsor 200 belongs, so as to ensure that the rope is prevented from flowing into the gap between the stators 210 in front of the front free impeller 100 in the presence or absence of the front duct 140; the cross-section of the front duct 140 is a straight surface, or a general airfoil-shaped cross-section of a ship's rotating duct.

[0013] Furthermore, there is a common divisor or no common divisor between the number of central blades 111 and / or the number of outer blades 112 of the front free impeller 100 and the number of blades of the rotor 220; the torsion direction of the central blades 111 is the same as the torsion direction of the blades of the front stator 210, and is opposite to the torsion direction of the blades of the rotor 220, so that the central blades 111 and the front stator 210 jointly enhance the reverse pre-rotation of the incoming flow in front of the rotor 220; the torsion direction / setting direction of the outer blades 112 should meet the following conditions: when the blades 112 rotate with the central blades 111, the direction of the auxiliary thrust generated by the blades 112 is consistent with the direction of the main thrust generated by the rotor 220.

[0014] Furthermore, the diameter of the rear free impeller 300 is 0.9-1.1 times the diameter of the rear stator 230; the blades 310 of the rear free impeller 300 are integrated, and can be either turbine blades or marine propeller blades, and the number of its blades has a common divisor with the number of blades of the rotor 220, or has no common divisor; the torsion direction of the rear blades 310 of the rear free impeller 300 is the same as the torsion direction of the blades of the rear stator 230, and is also the same as the torsion direction of the blades of the rotor 220, so that the rear blades 310 and the rear stator 230 can jointly recover the energy of the water flow behind the rotor 220.

[0015] Preferably, the front electric cutter 400 and the rear electric cutter 500 are both disc blades; and the rolling bearing is made of engineering plastics with self-lubricating function.

[0016] Preferably, the cable pipe and the lubricating oil pipe are laid along the bracket 930, the front stator 210, the rear stator 230, and the tail shaft sleeve 910 to the front and rear electric cutters and the front and rear free impellers to supply power to the electric cutters and oil to the rolling bearings.

[0017] Furthermore, the cable pipe and the lubricating oil pipe pass through the conical guide tube 240 and enter the interior of the pump-jet propeller 200.

[0018] A working method of an anti-entanglement pump-jet propulsion device, using the above-mentioned anti-entanglement pump-jet propulsion device; when working: the front duct 140 and the conical duct 240 form a circumferential shielding for the rotor 220, so that the rope can only flow from the front part of the front duct 140 when sailing forward, and can only flow from the rear part of the conical duct 240 to the pump-jet propeller 200 when sailing backward; when the ship's main engine is running forward, it drives the 220 rotor to rotate, and the rotation of the rotor 220 produces a suction effect, so that the water flows from the front to the back, and the front free impeller rotates; or when the ship's main engine is running backward, the water flows from the back to the front, and when the water flows through the rear free impeller, the rear free impeller The impeller rotates; when sailing forward, the rope flows from the front to the front free impeller 100, and when sailing backward, the rope flows from the rear to the rear free impeller 300; the rope is rotated by the front or rear free impeller, and gradually slides to the vicinity of the electric cutter under the action of the water flow, so that it cannot be entangled with the rotor 220; at this time, the rotor 220 can still rotate to push the ship to sail; because the rope is entangled on the front or rear free impeller, the streamline and flow of the water flow reaching the rotor 220 are changed, resulting in a change in the speed; from the change in the speedometer reading, the driver determines that the free impeller is entangled, and the driver starts the front or rear electric cutter to cut the rope.

[0019] The basic principle of the present invention is to use a freely rotating impeller to meet the rope before the propeller, and to wrap around the rope, preventing the rope from flowing to the propeller, thereby preventing the rope from wrapping around the propeller, and then cutting it.

[0020] The beneficial effects of the present invention are:

[0021] 1) The free impeller is used to rotate the rope before the propeller, which prevents the rotor from being entangled. When untangling, there is no need to stop the ship, which is a clever design.

[0022] 2) It can prevent rope entanglement when sailing forward or backward.

[0023] 3) The reverse pre-swirl formed by the front free impeller and the front stator, and the energy recovery formed by the rear free impeller and the rear stator are both beneficial to improving the working efficiency of the propeller.

[0024] 4) The design of the front duct and the tapered duct can effectively prevent the rope from flowing into the gap between the free impeller and the stator.

[0025] 5) Since the circumference of the impeller hub is small, it is difficult to arrange more blades, while the circumference of the duct is long, more blades can be arranged. Therefore, short central blades are arranged to appropriately increase the gap and make it easier to wind the rope. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a schematic diagram of the overall layout of the anti-winding pump-jet propulsion device, including two structural forms (a) and (b).

[0027] Figure 2 It is a schematic diagram of the combination of a pump-jet propeller and front and rear free impellers.

[0028] Figure 3 It is a schematic cross-sectional view of the front free impeller in the first embodiment.

[0029] Figure 4 It is a schematic cross-sectional view of the front free impeller in the second embodiment.

[0030] Figure 5 It is a cross-sectional schematic diagram showing the rear free impeller mounted on the shaft of the rear stator.

[0031] In the figure, 900. hull, 910. tail shaft sleeve, 920. tail shaft, 930. bracket, 100. front free impeller, 110. front blades, 111. center blades, 112. outer blades, 120. front free impeller hub, 130. front free impeller rolling bearing, 140. front duct, 141. inner blades of the front duct, 150. front sleeve, 200. pump-jet propulsion, 210. front stator, 220. rotor, 230. rear stator, 240. tapered duct, 300. rear free impeller, 310. rear blades, 311. inner blades of the rear duct, 320. rear free impeller hub, 330. rear free impeller rolling bearing, 340. rear free impeller duct, 400. front electric cutter, 500. rear electric cutter. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] Embodiment 1:

[0034] See also Figure 1 A pump-jet propulsion device for preventing propellers from being entangled comprises, from front to rear, a front free impeller 100, a pump-jet propeller 200, a rear free impeller 300, a front electric cutter 400, and a rear electric cutter 500;

[0035] See also Figure 1-Figure 5The front blades 110 of the front free impeller 100 are connected to the front impeller hub 120 and are evenly distributed in a radial shape along the circumference of the front impeller hub 120. The front impeller hub 120 is fixed to the outer ring of the rolling bearing 130. The inner ring of the rolling bearing 130 is fixed to the sleeve 150. The sleeve 150 can be fixed to the tail shaft sleeve 910 connected to the hull 900 by welding or fasteners; the front stator 210 of the pump-jet propeller 200 is sleeved on the tail shaft sleeve 910, the rotor 220 of the pump-jet propeller 200 is connected to the tail shaft 920 extending out of the tail shaft sleeve 910, and the conical duct 240 is connected to the hull 900 through the bracket 930; the blades 310 of the rear free impeller 300 are connected to the rear impeller hub 320 and are evenly distributed in a radial shape along the circumference of the rear impeller hub 120. The hub 320 is evenly distributed in a radial pattern in the circumferential direction. The rear impeller hub 320 is fixed on the outer ring of the rolling bearing 330. The inner ring of the rolling bearing 330 is fixed on the sleeve 350. The sleeve 350 can be fixed on the shaft of the rear stator 230 by welding or fasteners. No less than two front electric cutters 400 are evenly fixed on the hub of the front stator 210, and are located in front of the front stator 210, opposite to the front free impeller 100, and the axis of the electric cutter 400 is parallel to the axis of the tail shaft sleeve 910. No less than two rear electric cutters 500 are evenly fixed on the shaft of the rear stator 230, and are located behind the rear stator 230, opposite to the rear free impeller 300, and the axis of the electric cutter 500 is parallel to the axis of the rear stator 230.

[0036] In this embodiment, see Figure 3 The front blade 110 of the front free impeller 100 is divided into two parts: a central blade 111 and an outer blade 112. The two parts are integrated. The diameter of the entire front blade 110 is 0.95-1.5 times the diameter of the front stator 210. The central blade 111 is a turbine blade, and the diameter of the blade is 0.95-1.2 times the diameter of the front stator 210. The outer blade 112 can be a marine propeller propeller blade or a natural extension of the central blade 111, which is a turbine blade. A front duct 140 is arranged at the outer edge of the front blade 110.

[0037] In this embodiment, front duct internal blades 141 are uniformly and radially arranged along the inner circumference of the front duct 140. The front duct internal blades 141 and the front blades 110 located in the duct 140 not only have the same blade section, but also have the same blade torsion direction. However, the length of the front duct internal blades 141 does not reach the front impeller hub 120. The rear part of the front duct 140 can shield the front part of the tapered duct 240 to prevent the rope from flowing into the gap between the front free impeller 100 and the front stator 210. The rear duct internal blades 311 are uniformly and radially arranged along the inner circumference of the rear duct 340. The rear duct internal blades 311 and the rear blades 310 have the same blade section, but also have the same blade torsion direction. However, the length of the rear duct internal blades 311 does not reach the rear impeller hub 320. The front part of the rear duct 340 can shield the rear part of the tapered duct 240 to prevent the rope from flowing into the gap between the rear free impeller 300 and the rear stator 230.

[0038] In this embodiment, see Figure 1 When the front duct 140 is provided, the rear portion of the front duct 140 can shield the front portion of the tapered duct 240 to which the pump-jet propulsor 200 belongs. When the front duct 140 is not provided (not shown in the accompanying drawings), the free impeller 100 can be placed inside the tapered duct 240 to which the pump-jet propulsor 200 belongs, so as to ensure that the rope is prevented from flowing into the gap between the front free impeller 100 and the front stator 210 in the presence or absence of the front duct 140. The cross-section of the front duct 140 can be a straight surface or a general airfoil cross-section of a ship's rotating duct.

[0039] In this embodiment, the number of the central blades 111 and / or the number of the outer blades 112 of the front free impeller 100 may have a common divisor with the number of blades of the rotor 220, or may have no common divisor; the torsion direction of the central blades 111 is the same as the torsion direction of the blades of the front stator 210 (that is, the torsion trends are consistent, but the respective torsion angles may be the same or different, and the "same direction" in the following text is for this purpose), and is opposite to the torsion direction of the blades of the rotor 220 (that is, the torsion trends are opposite, but the absolute values ​​of the respective torsion angles may be the same or different, and the "different directions" in the following text is for this purpose), so that the central blades 111 and the front stator 210 jointly enhance the reverse pre-rotation of the incoming flow in front of the rotor 220; the torsion direction / setting direction of the outer blades 112 should meet the following conditions: when the blades 112 rotate with the aforementioned blades 111, the direction of the auxiliary thrust generated by the blades 112 is consistent with the direction of the main thrust generated by the rotor 220.

[0040] In this embodiment, see Figure 5, the diameter of the rear free impeller 300 is 0.9-1.1 times the diameter of the rear stator 230; the blades 310 of the rear free impeller 300 are integrated, and can be either turbine blades or marine propeller blades, and the number of its blades can have a common divisor with the number of blades of the rotor 220, or there can be no common divisor; the torsion direction of the blades 310 of the rear free impeller 300 is the same as the torsion direction of the blades of the rear stator 230, and is also the same as the torsion direction of the blades of the rotor 220, so that the blades 310 and the rear stator 320 jointly recover the energy of the water flow behind the rotor 220; preferably, the rear free impeller 300 is inside the conical duct 240.

[0041] In this embodiment, see Figure 1 The front and rear electric cutters all adopt disc blades.

[0042] In this embodiment, the rolling bearing is preferably made of engineering plastics with self-lubricating function.

[0043] In this embodiment, the cable pipe and the lubricating oil pipe can be laid along the fixed structural parts such as the bracket 930, the front stator 210, the rear stator 230, the tail shaft sleeve 910 to the front and rear electric cutters and the front and rear free impellers to supply power to the electric cutters and oil to the rolling bearings. If necessary, the cable pipe and the lubricating oil pipe can pass through the tapered duct 240 to enter the interior of the pump-jet propulsor 200.

[0044] The basic principle of the anti-entanglement pump-jet propulsion device is that the free-rotating impeller meets the rope before the propeller, entangles the rope, prevents the rope from flowing to the propeller, thereby preventing the rope from entanglement with the propeller, and then cuts it.

[0045] During operation: First, the front duct 140 and the conical duct 240 form a circumferential shield for the rotor 220, so that the rope can only flow to the propeller from the front (when sailing forward) and the rear (when sailing reverse) of the duct. This first ensures that the rope cannot flow into the propeller from other directions, reducing the probability of the rope being entangled in the rotor 220.

[0046] Secondly, when the ship's main engine is running, it drives the 220 rotor to rotate. The rotor 220 rotates, generating a suction effect, causing the water to flow from front to back (when sailing forward) or from back to front (when sailing backward). When the water flows through the front and rear free impellers, the front and rear free impellers rotate. When sailing forward, the rope flows from the front to the front free impeller 100, and when sailing backward, the rope flows from the rear to the rear free impeller 300. The rope is rotated by the free impeller and gradually slides to the vicinity of the electric cutter under the action of the water flow, so that it cannot be entangled with the rotor 220. The rotor 220 can still rotate to drive the ship to sail. Because the rope is wrapped around the free impeller, the streamline and flow of the water reaching the rotor 220 are changed, resulting in a change in the speed. From the change in the speedometer reading, the driver can judge that the free impeller is entangled, and the driver can start the electric cutter in the cab to cut the rope.

[0047] When not working: just turn off the electric cutter.

[0048] Embodiment 2:

[0049] The difference between this embodiment and the first embodiment is that:

[0050] See also Figure 4 The front blades 110 of the front free impeller 100 are divided into a central blade 111 and an outer blade 112, and are split. At this time, a front duct 140 is arranged at the top edge of the central blade 111, and then the outer blades 112 are uniformly arranged radially along the outer circumference of the front duct 140. The number of blades of the central blade 111 and the outer blade 112 can be the same or different, and the front duct 140 is supported by the top edge of the blades it accommodates.

[0051] Continue to see Figure 4 , front duct internal blades 141 are uniformly and radially arranged along the inner circumference of the front duct 140, the front duct internal blades 141 and the front blades 110 located in the duct 140 not only have the same blade section, but also have the same blade twisting direction, but the length of the front duct internal blades 141 does not reach the front impeller hub 120; the rear part of the front duct 140 can shield the front part of the tapered duct 240 to prevent the rope from flowing into the gap between the front free impeller 100 and the front stator 210;

[0052] See also Figure 5 The rear duct internal blades 311 are evenly and radially arranged along the inner circumference of the rear duct 340. The rear duct internal blades 311 have not only the same blade section as the rear blades 310, but also the same blade torsion direction. However, the length of the rear duct internal blades 311 does not reach the rear impeller hub 320. The rear part of the rear duct 340 can shield the rear part of the conical duct 240 to prevent the rope from flowing into the gap between the rear free impeller 300 and the rear stator 230.

[0053] The rest is the same as in the first embodiment.

[0054] The above are preferred embodiments of the present invention. A person skilled in the art may make various changes or improvements on this basis. Without departing from the longitudinal concept of the present invention, these changes or improvements should fall within the scope of protection required by the present invention.

Claims

1. An anti-entanglement pump-jet propulsion device, characterized in that: From front to rear in the axial direction, it includes a front free impeller (100), a front stator (210), a rotor (220), a rear stator (230), and a rear free impeller (300); At least one front electric cutting knife (400) is fixedly arranged at the front of the front stator (210); At least one rear electric cutting knife (500) is fixedly arranged at the rear of the rear stator (230); The front stator (210), the rotor (220), the rear stator (230), and an externally fixed conical duct (240); the rear free impeller (300) is located in the conical duct (240), or the rear free impeller (300) is fixedly connected to a rear duct (340), and the rear end of the rear duct (340) is sleeved outside the conical duct (240), and the gap between the rear duct (340) and the conical duct (240) is smaller than the size of an object that may be entangled; The front free impeller (100) is arranged inside the conical duct (240), or the front free impeller (100) is fixedly connected to a front duct (140), the outer inner diameter of the front duct (140) is less than or equal to the outer diameter of the front free impeller (100), and the rear end of the front duct (140) is sleeved outside the conical duct (240), and the gap between the front duct (140) and the conical duct (240) is smaller than the size of an object that may be entangled.

2. The anti-winding pump-jet propulsion device according to claim 1, characterized in that: The front blades (110) of the front free impeller (100) are connected to the front impeller hub (120) and are evenly distributed in a radial shape along the circumference of the front impeller hub (120); the front impeller hub (120) is fixed to the outer ring of the front rolling bearing (130); the inner ring of the front rolling bearing (130) is fixed to the front sleeve (150); and the front sleeve (150) is fixed to the tail shaft sleeve (910) connected to the hull (900) by welding or fasteners; The front stator (210) of the pump-jet propulsion device (200) is sleeved on the tail shaft sleeve (910), the rotor (220) of the pump-jet propulsion device (200) is connected to the tail shaft (920) extending out of the tail shaft sleeve (910), and the conical guide tube (240) is connected to the hull (900) through the bracket (930); The rear blades (310) of the rear free impeller (300) are connected to the rear impeller hub (320) and are evenly distributed in a radial shape along the circumference of the rear impeller hub (320). The rear impeller hub (320) is fixed to the outer ring of the rear rolling bearing (330). The inner ring of the rear rolling bearing (330) is fixed to the rear sleeve (350). The rear sleeve (350) is fixed to the shaft of the rear stator (230) by welding or fasteners. No less than two front electric cutters (400) are evenly fixed on the hub of the front stator (210) and are located in front of the front stator (210) and opposite to the front free impeller (100). The axis of the front electric cutter (400) is parallel to the axis of the tail shaft sleeve (910); No less than two rear electric cutters (500) are evenly fixed on the shaft of the rear stator (230) and are located behind the rear stator (230) and opposite to the rear free impeller (300). The axis of the rear electric cutter (500) is parallel to the axis of the rear stator (230).

3. The anti-entanglement pump-jet propulsion device according to claim 2, characterized in that: Front duct internal blades (141) are uniformly arranged in a centripetal shape along the inner circumference of the front duct (140); the front duct internal blades (141) and the front blades (110) located in the front duct (140) have the same blade section and the same blade twisting direction; however, the length of the front duct internal blades (141) does not reach the front impeller hub (120); the rear part of the front duct (140) can shield the front part of the conical duct (240) to prevent the rope from flowing into the gap between the front free impeller (100) and the front stator (210); The rear duct internal blades (311) are uniformly arranged in a centripetal shape along the inner circumference of the rear duct (340); the rear duct internal blades (311) and the rear blades (310) not only have the same blade section, but also have the same blade twisting direction; however, the length of the rear duct internal blades (311) does not reach the rear impeller hub (320); when the rear duct (340) is arranged, the front part of the rear duct (340) can shield the rear part of the conical duct (240) to prevent the rope from flowing into the gap between the rear free impeller (300) and the rear stator (230); when the rear duct (340) is not arranged, the rear free impeller (300) is inside the conical duct (240).

4. The anti-entanglement pump-jet propulsion device according to claim 2, characterized in that: The front blades (110) of the front free impeller (100) are divided into two parts: a central blade (111) and an outer blade (112); The diameter of the entire front blade (110) is 0.95-1.5 times the diameter of the front stator (210); The outer blades (112) are marine propeller blades, or turbine blades naturally extended from the central blades (111).

5. The anti-entanglement pump-jet propulsion device according to claim 4, characterized in that: When the front blade (110) is of an integrated type: the front duct (140) is fixedly arranged on the outer edge of the front blade (110); When the front blade (110) is of split type: the front duct (140) is arranged at the top edge of the central blade (111), and the outer blades (112) are evenly and radially arranged along the outer circumference of the front duct (140). At this time, the number of blades of the central blade (111) and the number of blades of the outer blade (112) can be the same or different; the front duct (140) is supported by the top edge of the central blade (111) accommodated therein.

6. The anti-entanglement pump-jet propulsion device according to claim 4, characterized in that: When the front duct (140) is provided, the rear portion of the front duct (140) can shield the front portion of the conical duct (240) to which the pump-jet propeller (200) belongs; When the front duct (140) is not provided, the front free impeller (100) is placed inside the conical duct (240) belonging to the pump-jet propeller (200) to ensure that the rope is prevented from flowing into the gap between the stators (210) in front of the front free impeller (100) with or without the front duct (140); The cross section of the front duct (140) is a straight surface, or a general airfoil cross section of a rotating duct of a ship.

7. The anti-entanglement pump-jet propulsion device according to claim 4, characterized in that: There is a common factor between the number of blades (111) at the center of the front free impeller (100) and / or the number of outer blades (112) and the number of blades of the rotor (220), or there is no common factor; The twisting direction of the central blades (111) is the same as the twisting direction of the blades of the front stator (210), and is opposite to the twisting direction of the blades of the rotor (220), so that the central blades (111) and the front stator (210) jointly enhance the reverse pre-rotation of the incoming flow in front of the rotor (220); the twisting direction / setting direction of the outer blades (112) should meet the following conditions: when the outer blades (112) rotate with the central blades (111), the direction of the auxiliary thrust generated by the outer blades (112) is consistent with the direction of the main thrust generated by the rotor (220).

8. The anti-entanglement pump-jet propulsion device according to claim 2, characterized in that: The diameter of the rear free impeller (300) is 0.9-1.1 times the diameter of the rear stator (230); the blades (310) of the rear free impeller (300) are integrated, and can be turbine blades or marine propeller blades, and the number of its blades has a common divisor with the number of blades of the rotor (220), or there is no common divisor; the torsion direction of the rear blades (310) of the rear free impeller (300) is the same as the torsion direction of the blades of the rear stator (230), and is also the same as the torsion direction of the blades of the rotor (220), so that the rear blades (310) and the rear stator (230) can jointly recover the energy of the water flow behind the rotor (220).

9. The anti-entanglement pump-jet propulsion device according to claim 2, characterized in that: The front electric cutting knife (400) and the rear electric cutting knife (500) are both disc blades; the front rolling bearing (130) and the rear rolling bearing (330) are made of engineering plastics with self-lubricating function.

10. The anti-entanglement pump-jet propulsion device according to claim 1, characterized in that: The cable pipe and the lubricating oil pipe pass through the conical guide tube (240) and enter the interior of the pump-jet propeller (200).

11. A working method of an anti-entanglement pump-jet propulsion device, characterized in that: The anti-entanglement pump-jet propulsion device according to claim 5 is used; when working: The front duct (140) and the conical duct (240) form a circumferential shielding for the rotor (220), so that the rope can only flow from the front of the front duct (140) when sailing forward, and can only flow from the rear of the conical duct (240) to the pump-jet propeller (200) when sailing backward; When the ship's main engine is running forward, it drives the rotor (220) to rotate, and the rotation of the rotor (220) generates a suction effect, so that the water flows from the front to the rear, and the front free impeller rotates; or when the ship's main engine is running reverse, the water flows from the rear to the front, and when the water flows through the rear free impeller, the rear free impeller rotates; When sailing forward, the rope flows from the front to the front free impeller (100), and when sailing backward, the rope flows from the rear to the rear free impeller (300); The rope is rotated by the front or rear free impeller and gradually slides down to the vicinity of the electric cutter under the action of the water flow, so that it cannot be entangled with the rotor (220); at this time, the rotor (220) can still rotate to propel the ship to sail; Since the rope is wound around the front or rear free impeller, the streamline and flow rate of the water reaching the rotor (220) are changed, resulting in a change in the ship's speed. From the change in the speedometer reading, the driver determines that the free impeller is wound, and then the driver starts the front or rear electric cutter to cut the rope.

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