Amphibious shackle opening and closing device

Abstract

The present invention relates to the technical field of lifting slings, in particular to a water-land dual-use shackle opening and closing device. It includes a pin shaft, a box body, a clamping plate, a pin shaft, a counterweight, a connecting piece, a hydraulic system. The pin shaft is provided with a central hole, the pin shaft penetrates through the shackle hole and one end of the mounting hole on the clamping plate to the inside of the pin shaft box body and is connected with a connecting plate. A shackle oil cylinder is installed on the connecting plate. One end of the pin shaft inside the pin shaft box body is provided with a fixed limit structure; the other end of the pin shaft extends to one side of the counterweight and is equipped with a radial sliding limit structure. Compared with the prior art, the axial fixation of the pin shaft adopts a two-end fixation method. The rightward movement of the pin shaft is restricted by the fixed limit structure on the pin shaft, and the leftward movement of the pin shaft is restricted by the radial sliding limit structure; this structure makes the fixed stiffness higher and at the same time avoids the eccentric load of the pin shaft.

Description

Technical Field

[0001] The present invention relates to the technical field of lifting slings, and in particular to a water-land dual-purpose shackle opening and closing device. Background Art

[0002] The shackle is a very widely used lifting rigging, mainly used in hoisting operations that are inconvenient or impossible for manual operation or support, such as offshore engineering, petrochemical engineering, bridge engineering, urban construction, and industrial installation. When hoisting heavy objects on land, generally, manual climbing is required to insert the pin into the shackle hole, and after hoisting, manual climbing is needed to pull out the pin from the shackle hole. When underwater, generally, professional divers or underwater robots are required to pull out the pin from the shackle hole, or directly cut the hoisting wire rope and sink the shackle into the water for no further use. There are also simple hydraulic devices fixed on the shackle to insert or pull out the pin of the shackle.

[0003] When used on land, for the existing shackles, manual climbing to the shackle position is required for loading and unloading. Especially at high altitudes, without protection, the operation is difficult and has great safety risks, and the loading and unloading efficiency is also very low. When used underwater, for the existing shackles, professional divers or underwater robots need to swim to the shackle position for loading and unloading. The operation is difficult, the cost is high, and the loading and unloading efficiency is low. If the hoisting wire rope is directly cut, the shackle will sink into the water and cannot be used again, resulting in economic losses.

[0004] For the simple hydraulic shackle, there is no emergency pin-pulling mechanism. When problems occur in the hydraulic power unit, manual pin-pulling is still required. The simple hydraulic shackle has no pin self-locking device and no balance weight, which is extremely likely to cause the shackle to tilt, resulting in the pin falling off, causing a hoisting accident, or difficult pin removal, and the operation reliability is relatively poor. The simple hydraulic shackle cannot be used for underwater operations either.

[0005] In the solution disclosed in 202011050139.9 announced by the State Intellectual Property Office, there are two ways to axially fix the pin: hydraulic fixation and mechanical fixation. Hydraulic fixation mainly uses one-way valves, and due to problems such as component quality and oil contamination, the reliability of hydraulic fixation is relatively low. Mechanical fixation has high reliability. The existing fixation method is to process a snap ring on the left side of the shackle body, and push the push rod into the snap ring to achieve two-way fixation. The axial force of the pin to the left is transmitted to the connecting bolt of the splint through the snap ring and the push rod. This solution increases the thickness of the splint, increases the diameter of the connecting bolt, and increases the weight of the equipment. Moreover, the axial force of the push rod on the snap ring is asymmetric in the circumferential direction, which will cause the pin to be eccentrically loaded. Summary of the Invention

[0006] The object of the present invention is to provide a water-land dual-purpose shackle opening and closing device with higher fixing stiffness and avoiding pin eccentric loading, overcoming the above-mentioned deficiencies of the prior art.

[0007] The present invention adopts the following technical solution:

[0008] An amphibious shackle opening and closing device includes a pin shaft box body, clamping plates, a pin shaft, a counterweight, a connecting member, a hydraulic system. A central hole is provided on the pin shaft. The pin shaft passes through the shackle hole and one end of the mounting hole on the clamping plate and extends into the pin shaft box body and is connected to a connecting plate. A shackle oil cylinder is installed on the connecting plate. One end of the pin shaft in the pin shaft box body is provided with a fixed limiting structure; the other end of the pin shaft extends to one side of the counterweight and is provided with a radial sliding limiting structure.

[0009] Compared with the prior art, the present invention adopting the above technical solution fixes the axial direction of the pin shaft in a way of fixing both ends. The rightward movement of the pin shaft is restricted by the fixed limiting structure on the pin shaft, and the leftward movement of the pin shaft is restricted by the radial sliding limiting structure; this structure makes the fixing stiffness higher and at the same time avoids the eccentric load of the pin shaft.

[0010] The preferred solution of the present invention is:

[0011] The fixed limiting structure is a left shoulder structure, and the sliding limiting structure is: a sealing cylinder, a wedge piston and a spring are sequentially arranged in the central hole at the other end of the pin shaft. A slider is installed on the wedge piston through a guide rail.

[0012] Four guide rails are evenly arranged on the wedge piston, and sliders are respectively installed on each guide rail. The extending ends of the sliders are placed outside the pin shaft, and a chute is provided on the pin shaft.

[0013] The central hole on the pin shaft is a blind hole structure, and the closed end is located on the right side of the pin shaft. The oil inlet port is located on the left side of the pin shaft and is placed in a sealed box.

[0014] The sealed box is a cylindrical barrel structure. The lower part of the sealed box is provided with a pin shaft box body. The pin shaft box body is a rectangular frame structure. The left part of the pin shaft is installed in the pin shaft box body through a connecting plate and a left shoulder structure respectively. A horizontal cross plate is arranged in the cylindrical barrel structure. A through hole is provided at the bottom end of the cylindrical barrel structure, and the through hole is communicated with the pin shaft box body.

[0015] The central hole of the pin shaft is a stepped hole structure. The oil inlet port is located in the pin shaft box body. The straight hole of the central hole where the sealing cylinder is located is larger than the diameter of the oil inlet port. The diameter of the central hole where the wedge piston is located is larger than the diameter of the central hole where the sealing cylinder is located. The central hole where the spring is located is a square hole structure, and the maximum diameter of the square hole structure is larger than the diameter of the central hole where the wedge piston is located.

[0016] A spring pad is arranged between the spring and the end of the wedge piston, and a travel switch is arranged on the wall of the central hole where the spring is located.

[0017] The hydraulic system uses two pumps in parallel to supply oil to the system. One-way valves, accumulators, pressure sensors, and a first reversing valve are successively installed on the outlet pipelines of the pumps. The first reversing valve is connected to a second reversing valve and a third reversing valve respectively. The wedge piston cylinder includes a wedge piston and a spring. The wedge piston cylinder is connected to the third reversing valve through a pilot-operated check valve. The shackle cylinder is connected in parallel with the wedge piston cylinder through the second reversing valve.

[0018] The first reversing valve is a two-position two-way reversing valve, and the second reversing valve and the third reversing valve are three-position four-way reversing valves respectively. Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of the present invention.

[0020] Figure 2 is Figure 1 the A-A sectional view of

[0021] Figure 3 is Figure 1 the B-B sectional view of

[0022] Figure 4 is a hydraulic system diagram. Detailed Description of the Invention

[0023] The present invention will be described in detail below in conjunction with the embodiments and the drawings:

[0024] An amphibious shackle opening and closing device, see attached Figure 1 to attached Figure 4 , in the figure: slider 1, wedge piston 2, travel switch one 3, spring 4, sealing cylinder 5, spring washer 6, steel ring one 7, counterweight 8, lifting ring 9, shackle 10, clamping plate 11, pin shaft box body 12, right side plate 1201, steel ring two 13, pin shaft 14, sealing box 15, through hole 1501, cylindrical barrel structure 1502, horizontal cross plate 1503, connecting plate 16, nut 17, bolt 18, I-beam 19, travel switch two 20, shackle cylinder 21, left shoulder structure 22, internally threaded steel plate 23, steel ring four 24, steel ring three 25, central hole 26, central through hole 27, hydraulic pump one 28, hydraulic pump two 29, one-way valve 30, accumulator 31, pressure sensor 32, first reversing valve 33, second reversing valve 34, third reversing valve 35, pilot-operated check valve 36, wedge piston cylinder 37, guide rail 38, installation vertical plate 39, intermediate web 40, sealing plate 41, filter 42, overflow valve 43, wire threading bent pipeline 44.

[0025] In this embodiment, a second steel ring 13 is provided on one side of the right side plate 1201 of the pin shaft housing 12. The second steel ring 13 is welded to the shackle 10 to support the pin shaft housing. A part of the pin shaft 14 is sleeved inside the second steel ring 13, and the left shoulder structure 22 of the pin shaft 14 is located inside the pin shaft housing 12 and on the left side of the second steel ring 13. The left shoulder structure 22 can be integrally formed with the pin shaft 14 or welded to the pin shaft 14 by welding.

[0026] The clamping plates 11 are placed inside and outside the two extending ends of the shackle 10, one on each of the left and right sides, for a total of four. Among them, two clamping plates 11 placed inside the two extending ends have the same specifications, and the other two clamping plates are respectively the right side plate 1201 of the pin shaft housing 12; the other clamping plate is the mounting vertical plate 39 connected to the I-beam 19, and the right side plate 1201 and the mounting plate vertical plate 39 have the same specifications.

[0027] The clamping plates inside and outside the same extending end are connected by bolts. Among them, at one place inside the pin shaft housing 12, an internally threaded steel plate 23 is used to connect with the bolts. Therefore, the installation space here is small, and it is inconvenient to install with nuts, so the internally threaded steel plate 23 is designed.

[0028] A first steel ring 7, a second steel ring 13, a third steel ring 25, and a fourth steel ring 24 are sleeved on the pin shaft 14. The third steel ring 25 and the fourth steel ring 24 are arranged between the clamping plate 11 and the pin shaft 14, and the second steel ring 13 is arranged between the pin shaft 14 and the right side plate 1201 of the pin shaft housing 12. The first steel ring 7, the second steel ring 13, the third steel ring 25, and the fourth steel ring 24 are all connected to the shackle 10 by welding.

[0029] A first steel ring 7 is installed between the pin shaft 14 and the mounting vertical plate 39. The mounting vertical plate 39 is connected to the I-beam 19, and the counterweight 8 is placed on the middle web 40 of the I-beam 19; the thickness of the first steel ring 7 is greater than the thickness of the second steel ring 13, and the second steel ring 13, the third steel ring 25, and the fourth steel ring 24 have the same thickness. The right side of the first steel ring 7 is in contact with the slider 1 to limit the leftward movement of the pin shaft 14.

[0030] A central hole 16 is provided on the pin shaft 14. The left port of the central hole 16 placed inside the pin shaft housing 12 is the inlet port for arranging hydraulic pipelines and electrical pipelines. After the pin shaft 14 passes through the through hole on the shackle 10 and the mounting holes on the clamping plate 11, one end of the pin shaft 14 extends into the pin shaft housing 12 and is connected to the connecting plate 16. A shackle oil cylinder 21 is installed below the connecting plate 16, and the shackle oil cylinder 21 is arranged parallel to the pin shaft 14. A second travel switch 20 is installed at the front end of the shackle oil cylinder 21, and a threading bend pipeline 44 for the first travel switch 3 is also provided on the pin shaft 14, and the threading bend pipeline 44 communicates with the central hole 26.

[0031] The other end of the pin shaft 14 extends to the side where the counterweight 8 is installed (in this embodiment, from Figure 1As shown on the left side), it is equipped with a slider 1. The pin shaft 14 has a left shoulder structure 22 in the pin shaft housing 12. In the center hole at the other end of the pin shaft 14, a sealing cylinder 5, a wedge piston 2, a guide rail 38, a first travel switch 3, and a spring 4 are arranged in sequence. The center hole 26 of the pin shaft 14 is a stepped hole structure. The sealing cylinder 5 is provided with a central through hole 27 for installing a hydraulic pipe joint. On the other side of the sealing cylinder 5, a wedge piston 2 is installed. The wedge piston 2 is equipped with a slider 1 through a guide rail 38, and a spring 4 is installed on one side of the wedge piston 2.

[0032] Four guide rails 38 are evenly arranged on the wedge piston 2. Each guide rail 38 is respectively connected to the dovetail structure on the slider 1 through a dovetail groove structure (or other groove structures can also be used for the connection between the guide rail 38 and the slider, not limited to the dovetail groove connection structure). The extended end of the slider 1 is outside the pin shaft 14, and the pin shaft 14 is provided with a chute structure for the slider 1 to move.

[0033] The center hole 26 on the pin shaft 14 is a blind hole structure. The closed end is on the right side of the pin shaft 14, and the oil inlet port is on the left side of the pin shaft 14 and is placed in the pin shaft housing 12.

[0034] The sealing box 15 is a cylindrical barrel structure 1502. The lower part of the sealing box 15 is installed on the pin shaft housing 12. The left part of the pin shaft 14 is respectively installed in the pin shaft housing 12 through a connecting plate 16 and a left shoulder structure 22. The left shoulder structure 22 is in contact with the second steel ring 13 on the pin shaft housing 12 to prevent the pin shaft 14 from moving to the right. A horizontal cross plate 1503 is arranged in the cylindrical barrel structure 1502, which provides an installation platform for components such as an oil tank, a motor, and a hydraulic valve block. A through hole 1501 is arranged at the bottom end of the cylindrical barrel structure 1502. The function of the through hole 1501 is to lead out hydraulic pipelines and wires from the sealing box and connect them to the hydraulic cylinder and the limit switch; the through hole 1501 is communicated with the inside of the pin shaft housing 12.

[0035] The center hole of the pin shaft 14 is a stepped hole structure. The inlet pipe and wire port is placed in the pin shaft housing 12. The diameter of the straight hole of the center hole 26 where the sealing cylinder 5 is located is larger than the diameter of the inlet pipe and wire port. The diameter of the center hole 26 where the wedge piston 2 is located is larger than the diameter of the center hole 26 where the sealing cylinder is located. Part of the center hole 26 where the spring 4 is located is a square hole structure, which is beneficial for installing two first travel switches 3. The maximum diameter of this square hole structure is larger than the diameter of the center hole 26 where the wedge piston 2 is located. One side of the spring 4 is installed on the sealing plate 41. A cylindrical boss structure can be added at the front end of the sealing plate 41, and this cylindrical boss structure extends into the inner circle of the spring 4 to position the spring to prevent deviation. A blind hole structure is formed between the sealing plate 41 and the center hole of the pin shaft 14.

[0036] A spring pad 6 is arranged between the spring 4 and the end of the wedge-shaped piston 2, and a first travel switch 3 is arranged on the wall of the central hole 26 where the spring 6 is located. The hydraulic system uses two pumps to supply oil to the system. The first hydraulic pump 28 and the second hydraulic pump 29 are arranged in parallel. Check valves 30, accumulators 31, pressure sensors 32 and first reversing valves 33 are successively installed on the outlet pipelines of the pumps. The first reversing valve 33 is respectively connected to the second reversing valve 34 and the third reversing valve 35. The wedge-shaped piston oil cylinder is composed of a wedge-shaped piston 2, a guide rail 38, a slider 1 and a spring 4. The wedge-shaped piston oil cylinder is connected to the third reversing valve 35 through a pilot-operated check valve 36. The shackle oil cylinder 21 is connected in parallel with the wedge-shaped piston oil cylinder through the second reversing valve 34. The first reversing valve 33 is a two-position two-way reversing valve, and the second reversing valve 34 and the third reversing valve 35 are respectively three-position four-way reversing valves. The reversing valves are controlled through ground control buttons and travel switches to realize the opening and closing of the shackle and the fixing of the pin 14. The extension of the wedge-shaped piston 2 is hydraulically driven, and the retraction is driven by the spring 4.

[0037] The hydraulic system is as Figure 4 shown in the figure. The actuators include a shackle oil cylinder 21 and a wedge-shaped piston oil cylinder. The shackle oil cylinder 21 completes the shackle release action of the pin 14. When the wedge-shaped piston oil cylinder extends, it drives the slider 1 to radially extend to complete the axial positioning of the pin 14. The control part includes reversing valves, check valves 30 and pilot-operated check valves 36. The power part includes accumulators 31, make-up oil pumps, DC motors and lithium batteries. The shackle release action is an intermittent and discontinuous movement, and the make-up oil pump plus the accumulator 31 is used as the power part solution. The working pressure of the accumulator 31 is 10 MPa. When it is lower than this value, the make-up oil pump starts to replenish oil for the accumulator 3l to maintain the working pressure of the accumulator 31. A filter 42 is arranged on the return oil pipeline to ensure the cleanliness of the oil. Two first hydraulic pumps 28 and second hydraulic pumps 29 are provided, one for work and one for standby. When the working first hydraulic pump 28 or its motor fails, the standby second hydraulic pump 29 starts (vice versa: when the second hydraulic pump 29 is the working pump, the first hydraulic pump 28 is the standby pump), improving the reliability of the system. The relief valve 43 ensures that the pump outlet pressure does not exceed 12 MPa.

[0038] For the branch of the shackle oil cylinder 21, its extension and retraction are controlled by the second reversing valve 34, and the pin 14 is driven to realize the opening and closing of the shackle and the buckling and unbuckling of the shackle. The first reversing valve 33 is a ball valve used to cut off the pipeline between the accumulator 31 and the oil cylinder to prevent the pressure of the accumulator 31 from decreasing due to leakage. The pressure sensor 32 is used to monitor the pressure of the accumulator 31 in real time as the basis for judging the start of the pump. The return oil of the shackle oil cylinder 21 flows into the fuel tank through the second reversing valve 34. The fuel tank is closed, and the internal pressure is 0 MPa.

[0039] The pin shaft 14 fixes the oil cylinder branch (i.e., the wedge piston oil cylinder branch), and its extension is controlled by the third reversing valve 35. Its retraction is achieved by the spring 4. When extending, the wedge piston 2 pushes the slider 1 to extend to axially position the pin shaft 14. The power for pushing is also provided by the accumulator 1. The hydraulic control check valve 36 is used to maintain the pressure in the oil chamber of the wedge piston to prevent the wedge piston 2 from retracting. To release the axial fixation, the third reversing valve 35 opens the hydraulic control check valve 36, and the oil flows into the oil tank through the third reversing valve 35. The electromagnetic action sequence table during the working process is shown in Table 1. All the electromagnets are de-energized in the intermediate state of the action, which can improve the working life of the electromagnetic coil and the reliability of the system.

[0040] Table 1 Electromagnetic action sequence table

[0041] Action 1YA 2YA 3YA 4YA 5YA Shackle + + - - - Buckle + - + - - Slider 1 extends + - - + - Slider 1 retracts + - - - +

[0042] In this embodiment, the axial fixation device of the pin shaft:

[0043] The pin shaft 14 is fixed by using the left shoulder structure 22 for limiting at the right end of the pin shaft 14 extending out of the slider 1. The oil enters the sealed cavity on the left side of the wedge piston 2 from the left end of the pin shaft 14 through the central hole 26 of the pin shaft 14. The pressure of the oil pushes the wedge piston 2 to move rightward. The wedge piston 2 pushes the slider 1 to radially extend through the guide rail 38. After the slider 1 extends out of the chute of the pin shaft 14, it serves as the shoulder on the right side of the pin shaft 14 to prevent the pin shaft 14 from moving leftward. Four sliders 1 are evenly arranged in the circumferential direction. When releasing the fixation, the spring force of the spring 4 on the right side pushes the wedge piston 2 to move leftward, and the slider 1 radially retracts under the drive of the guide rail 38 to release the fixation of the pin shaft 14. The steel ring 1 is welded on the body of the shackle 10. Two travel switches 1 need to be installed on the wedge piston 2 as the basis for triggering the third reversing valve 35 to lose power.

[0044] To prevent the slider 1 and the guide rail 38 from rusting, a polyethylene guide rail 38 wrapped with stainless steel is used, and the material of the slider 1 is austenitic stainless steel. The spring 4 should have anti-rust ability.

[0045] Advantages of the improved invention:

[0046] 1. The axial fixation of the pin shaft 14 adopts a two-end fixation method. The left shoulder structure 22 on the pin shaft 14 restricts the pin shaft 14 from moving rightward, and the radially moving slider 1 restricts the pin shaft 14 from moving leftward. This structure makes the fixation stiffness higher and avoids the eccentric load on the pin shaft 14.

[0047] 2. The hydraulic system adopts two sets of motor pumps, one for operation and one for standby. When one motor pump fails, the other starts to improve the reliability of the system. The wedge piston cylinder adopts a hydraulic control one-way valve 36 to prevent the slider 1 from retracting due to radial movement during the fixing stage. The moving hydraulic fluid of the shackle cylinder 21 and the wedge piston cylinder is provided by the accumulator 31. The outlet pressure of the accumulator 31 is collected by the pressure sensor 32. When the pressure is lower than 10 MPa, the pump starts to refill the accumulator 31 to maintain its working pressure. The pump refills the accumulator 31 once for each operation.

[0048] The protection scope of the present invention is not limited to the above examples. For example, in the radial limit structure on the right side, a tapered guide rail structure can be provided on the cylindrical piston cylinder, and the guide rail structure cooperates with the slider to achieve radial limit. In addition, there is a fixed limit structure on the left side of the pin shaft and a radial sliding limit structure on the right side of the pin shaft, which are all regarded as within the protection scope of the present invention.

[0049] The expressions such as left side and right side in the present invention are defined according to the positional relationship in the figures of this embodiment. The present invention is not limited to the structure formed by interchanging the left and right positions, which are all regarded as within the protection scope of the present invention.

[0050] The underwater shackle opening and closing device listed in this embodiment can realize the opening and closing of the lifting shackle in complex underwater conditions where it is not easy to operate. Of course, it is not limited to applications in onshore environments.

Claims

1. An amphibious shackle opening and closing device, comprising a pin shaft box body, a clamping plate, a pin shaft, a counterweight block, a connecting piece, and a hydraulic system, characterized in that : A central hole is provided on the pin shaft. The pin shaft passes through the shackle hole and one end of the mounting hole on the clamping plate and extends into the pin shaft box body and is connected to the connecting plate. A shackle oil cylinder is installed on the connecting plate. One end of the pin shaft in the pin shaft box body is provided with a fixed limit structure; The other end of the pin shaft extends to one side of the counterweight block and is equipped with a radial sliding limit structure; The fixed limit structure is a left shoulder structure. The sliding limit structure is: a sealing cylinder, a wedge piston and a spring are sequentially arranged in the central hole at the other end of the pin shaft. A slider is installed on the wedge piston through a guide rail; Four guide rails are evenly arranged on the wedge piston. A slider is installed on each guide rail respectively. The extended end of the slider is placed outside the pin shaft, and a chute is provided on the pin shaft; The central hole on the pin shaft is a blind hole structure. The closed end is located on the right side of the pin shaft. The oil inlet port is located on the left side of the pin shaft and is placed in the pin shaft box; The central hole of the pin shaft is a stepped hole structure. The incoming line port is located in the pin shaft box body. The diameter of the straight hole of the central hole where the sealing cylinder is located is larger than the diameter of the incoming line port. The diameter of the central hole where the wedge piston is located is larger than the diameter of the central hole where the sealing cylinder is located. The central hole where the spring is located is a square hole structure. The maximum diameter of the square hole structure is larger than the diameter of the central hole where the wedge piston is located; The extension of the wedge piston is driven by hydraulic pressure, and the retraction is driven by the spring.

2. The amphibious shackle opening and closing device according to claim 1, characterized in that: The sealing box is a cylindrical barrel structure. The lower part of the sealing box is provided with a pin shaft box body. The pin shaft box body is a rectangular frame structure. The left part of the pin shaft is respectively installed in the pin shaft box body through the connecting plate and the left shoulder structure. A horizontal cross plate is arranged in the cylindrical barrel structure. A through hole is provided at the bottom end of the cylindrical barrel structure, and the through hole is communicated with the pin shaft box body.

3. The amphibious shackle opening and closing device according to claim 1, characterized in that: A spring pad is arranged between the spring and the end of the wedge piston. A travel switch is arranged on the wall of the central hole where the spring is located.

4. The amphibious shackle opening and closing device according to claim 1, characterized in that: The hydraulic system uses two pumps in parallel to supply oil to the system. A one-way valve, an accumulator, a pressure sensor and a first reversing valve are sequentially installed on the outlet pipeline of the pump. The first reversing valve is respectively connected to the second reversing valve and the third reversing valve. The wedge piston oil cylinder includes a wedge piston and a spring. The wedge piston oil cylinder is connected to the third reversing valve through a hydraulic control one-way valve. The shackle oil cylinder is connected in parallel with the wedge piston oil cylinder through the second reversing valve.

5. The amphibious shackle opening and closing device according to claim 4, characterized in that: The first reversing valve is a two-position two-way reversing valve, and the second reversing valve and the third reversing valve are respectively three-position four-way reversing valves.

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