Pump storage power station unit complete switchgear

Abstract

Provided is a complete set of switch equipment for pumped storage power station units, which comprises three single-phase switch cabinet devices that are electrically connected to achieve three-phase mechanical linkage, the three-phase switch equipment is divided into three phases, the circuit breaker controlled by the single-phase switch cabinet device is formed by two vacuum arc chambers in parallel, the single-phase switch cabinet device comprises a transmission box and a mechanism box that are fixedly connected and distributed in front and back, a spring operating mechanism is installed in the mechanism box, the output crank of the spring operating mechanism is connected with the input end of a four-bar linkage transmission mechanism arranged in the transmission box, and the two output ends of the four-bar linkage transmission mechanism are connected with the lower ends of the insulation pull rods of the two vacuum arc chambers of the corresponding phase circuit breaker. The utility model solves the problems of long procurement cycle, high procurement cost and untimely after-sales service caused by excessive dependence of pumped storage power station unit switch equipment on imported equipment, improves the shunt capacity and breaking capacity of the circuit breaker, solves the problem of heating of the large-current switch, and the opening and closing action is reliable, rapid and compact in structure.

Description

Technical Field

[0001] This utility model belongs to the field of switchgear technology, specifically relating to a complete set of switchgear for pumped storage power station units. Background Technology

[0002] Pumped storage power stations, as key power facilities with multiple functions including peak shaving, frequency regulation, phase regulation, energy storage, system backup, and black start, occupy an important position in the current energy system. They are not only the most technologically mature, with the best emission reduction effects throughout their entire life cycle and the potential for large-scale development as a major regulating power source, but they can also work well with energy systems such as wind power, solar power, and nuclear power, playing a crucial role in ensuring power security and promoting the healthy development of new energy sources.

[0003] With the continuous advancement of smart grid construction in my country, pumped storage power stations have become an important component of the smart grid due to their flexible operation and rapid response. However, the complete set of switchgear for pumped storage power stations in my country, including generator circuit breakers, starting switches, drive switches, electric braking switches, phase succession switching switches, and starting bus sectionalizing disconnect switches, has long relied on imports. This over-reliance on imported equipment has directly led to a series of problems such as long procurement cycles, high procurement costs, and untimely after-sales service, seriously restricting the construction progress and operational efficiency of pumped storage power stations in my country.

[0004] To break this situation, meet the demand for pumped storage power stations driven by the rapid growth of new energy sources, and address the numerous drawbacks of imported equipment, developing domestically produced pumped storage power station unit switchgear with independent intellectual property rights has become an urgent need for the industry. This is of great significance for promoting the independent development of my country's pumped storage industry. Utility Model Content

[0005] The technical problem solved by this utility model is to provide a complete set of switchgear for pumped storage power station units. It adopts a three-phase, box-type structure with three single-phase switchgear units electrically connected to achieve three-phase mechanical linkage. This facilitates the independent installation, maintenance, and repair of each single-phase unit. Simultaneously, the three-phase mechanical linkage ensures the coordination and consistency of the three-phase operation. This solves a series of problems caused by the excessive reliance on imported switchgear for pumped storage power station units, resulting in long procurement cycles, high procurement costs, and untimely after-sales service. The circuit breaker uses two vacuum interrupters connected in parallel, which improves the circuit breaker's shunt capacity and breaking capacity, effectively solving the problem of overheating in high-current switches and enhancing the stability of equipment operation. The opening and closing actions are completed through the cooperation of a spring operating mechanism and a four-bar linkage transmission mechanism, resulting in high transmission efficiency, reliable and rapid opening and closing actions, a compact structure, and space-saving installation. It also facilitates the overall commissioning and operation management of the equipment.

[0006] The technical solution adopted in this utility model is as follows: a complete set of switchgear for a pumped storage power station, including three single-phase switchgear units that achieve three-phase mechanical linkage through electrical connection, and a three-phase box-type switchgear. The circuit breaker controlled by the single-phase switchgear unit is composed of two vacuum interrupters connected in parallel. The single-phase switchgear unit includes a transmission box and a mechanism box that are distributed and fixedly connected at the front and rear. A spring operating mechanism is installed in the mechanism box. The output crank arm of the spring operating mechanism is connected to the input end of a four-bar linkage mechanism located in the transmission box. The two output ends of the four-bar linkage mechanism are connected to the lower ends of the insulating pull rods of the two vacuum interrupters of the corresponding phase circuit breaker. The opening and closing actions are completed with the cooperation of the spring operating mechanism and the four-bar linkage mechanism.

[0007] The spring operating mechanism includes an energy storage motor, an energy storage spring, a camshaft, and a cam. The output end of the energy storage motor is connected to the camshaft, which is rotatably mounted in the mechanism housing, via a gear transmission group. The lower ends of two energy storage springs symmetrically distributed on both sides of the camshaft are connected to the corresponding ends of the camshaft. A switch shaft is rotatably mounted in the mechanism housing via a bearing below the camshaft. The cam, which is centrally mounted on the camshaft, corresponds to the position of the crank arm roller on the switch shaft and moves against each other when the camshaft or the switch shaft rotates. The output crank arm, which is centrally fixed on the switch shaft, is connected to the input end of a four-bar linkage mechanism via a connecting plate. The camshaft is equipped with a mechanism for limiting the clockwise rotation of the switch shaft when the switch is closed.

[0008] Furthermore, the bottom surface of the mechanism box is provided with a buffer device for absorbing and buffering the energy on the switch shaft during the opening and closing processes. The buffer device includes an opening buffer for absorbing excess energy during the opening process, a closing buffer for absorbing excess energy during the closing process, and a positioning buffer for absorbing the impact energy of the opening process and positioning the moving parts.

[0009] Furthermore, the opening and closing buffers are rubber buffers, and the positioning buffer is an oil buffer for opening positioning.

[0010] Furthermore, the four-bar linkage includes a transmission crank arm, a main connecting plate, and two main crank arms. Two crank arm supports and a transmission crank arm support are fixed to the bottom plate of the transmission box. The transmission crank arm has a triangular plate-like structure. The corner where the two short sides of the transmission crank arm intersect is hinged to one side of the transmission crank arm support. One end of the transmission crank arm is hinged to the output crank arm in the spring operating mechanism via a connecting plate. One of the main crank arms is hinged to the other side of the transmission crank arm support, and the upper end of this main crank arm is concentrically hinged to the output connecting plate and one end of the main connecting plate. The lower end of this main crank arm is connected to one of the insulating pull rods. The lower end is connected, and the other end of the transmission crank arm is hinged to the other end of the output connecting plate; another main crank arm is hinged to a crank arm support on the side away from the mechanism box, and the upper end of the main crank arm is hinged to the other end of the main connecting plate, while the lower end of the main crank arm is connected to the lower end of another insulating pull rod. When the main connecting plate moves back and forth, the two main crank arms respectively control the up and down of the two insulating pull rods. A buffer crank arm is provided in the middle position of the two main crank arms, which is hinged to the other main crank arm. One end of the buffer crank arm is hinged to the middle of the main connecting plate, while the other end of the buffer crank arm is connected to a buffer provided on the bottom plate of the transmission box.

[0011] Advantages of this utility model compared to the prior art:

[0012] 1. This technical solution adopts a three-phase box-type structure with three single-phase switchgear equipment connected by electrical connection to achieve three-phase mechanical linkage. This facilitates the independent installation, maintenance and repair of each single-phase equipment. At the same time, the three-phase mechanical linkage can ensure the coordination and consistency of the three-phase operation. It solves a series of problems caused by the excessive reliance on imported equipment for pumped storage power station units, which leads to long procurement cycles, high procurement costs and untimely after-sales service. Each box is an independent unit. The opening and closing action is completed by the cooperation of spring operating mechanism and four-bar transmission mechanism. The transmission efficiency is high, the opening and closing action is reliable and fast, the structure is compact, saves installation space, and is also conducive to the overall commissioning and operation management of the equipment.

[0013] 2. The circuit breaker in this technical solution is composed of two vacuum interrupters connected in parallel, which can improve the shunt capacity and breaking capacity of the circuit breaker, effectively solve the problem of heat generation in high-current switches, reduce heat generation, enhance the stability of equipment operation, and eliminate the use of SF6 gas, which is in line with the current trend of green and environmentally friendly switch applications.

[0014] 3. This technical solution, by setting up a buffer device, can effectively mitigate the energy impact during the opening and closing process, reduce the wear of mechanical parts, and improve the stability and service life of the equipment.

[0015] 4. The symmetrical arrangement of the energy storage springs in this technical solution makes the output of the cam more stable, the force distribution on the camshaft more reasonable, the structure is simple, the design is novel, and the product has high reliability. Attached Figure Description

[0016] Figure 1 This is a front view of the structure of this utility model;

[0017] Figure 2 This is a right view of the structure of this utility model. Detailed Implementation

[0018] The following will be based on the embodiments of this utility model. Figure 1-2 The technical solutions in the embodiments of this utility model are clearly and completely described herein. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0019] It should be noted that, unless otherwise stated herein, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] Pumped storage power station unit switchgear, such as Figure 1-2As shown, this is a three-phase modular switchgear system comprising three single-phase switchgear units electrically connected to achieve three-phase mechanical linkage. The circuit breaker controlled by each single-phase switchgear unit uses two vacuum interrupters connected in parallel, which improves the shunt capacity and breaking capacity of the circuit breaker, effectively solves the problem of overheating in high-current switches, reduces heat generation, enhances equipment operational stability, and eliminates the use of SF6 gas, aligning with the current trend of green and environmentally friendly switch applications. The single-phase switchgear unit includes a transmission box 15 and a mechanism box 6, which are distributed and fixedly connected front and rear. The mechanism box 6 is constructed from eight thick steel plates bent and welded together. The transmission box 15 is made of welded I-beams and channel steel. The mechanism box 6 and the transmission box 15 are welded together by a 20mm thick processed steel plate, and the overall structure has high strength and assemblability. A spring operating mechanism 7 is installed in the mechanism box 6. The output crank arm of the spring operating mechanism 7 is connected to the input end of the four-bar linkage mechanism located in the transmission box 15. The two output ends of the four-bar linkage mechanism are connected to the lower ends of the insulating pull rods 17 of the two vacuum interrupters of the corresponding phase circuit breaker. The opening and closing actions are completed with the cooperation of the spring operating mechanism 7 and the four-bar linkage mechanism.

[0022] The above structure uses a three-phase box-type structure with three single-phase switchgear devices connected by electrical connection to achieve three-phase mechanical linkage. This facilitates the independent installation, maintenance and repair of each single-phase device. At the same time, the three-phase mechanical linkage can ensure the coordination and consistency of the three-phase operation. This solves a series of problems caused by the excessive reliance on imported equipment for pumped storage power station units, which leads to long procurement cycles, high procurement costs and untimely after-sales service. Each box is an independent unit, and the opening and closing actions are completed through the cooperation of spring operating mechanism and four-bar linkage transmission mechanism. The transmission efficiency is high, the opening and closing actions are reliable and rapid, the structure is compact, saves installation space, and is also conducive to the overall commissioning and operation management of the equipment.

[0023] The spring operating mechanism 7 and the four-bar linkage mechanism adopt a three-phase box-type structure. The arc extinguishing device adopts a vacuum arc extinguishing chamber. Each phase consists of two vacuum arc extinguishing chambers connected in parallel. The four-bar linkage mechanism adopts a longitudinal arrangement. The spring operating mechanism 7 and the two arc extinguishing chambers are arranged in a straight line, one in front of the other. Air insulation is used between phases. Each of the three phases uses three spring operating mechanisms 7 and four-bar linkage mechanisms, which can realize three-phase mechanical linkage. The overall structure is simple and compact.

[0024] The specific structure of the spring operating mechanism 7 is as follows: The spring operating mechanism 7 includes an energy storage motor 8, an energy storage spring 10, a camshaft 4, and a cam 9. The energy storage motor 8 can be operated manually or electrically. The output end of the energy storage motor 8 is connected to the camshaft 4, which is rotatably mounted in the mechanism housing 6, through a gear transmission group 11. The gear transmission group 11 has high transmission efficiency and low noise. The lower ends of the two energy storage springs 10, which are symmetrically distributed on both sides of the camshaft 4, are connected to the corresponding ends of the camshaft 4. The symmetrical arrangement of the energy storage springs 10 makes the output of the cam 9 more stable and the force distribution of the camshaft 4 more reasonable. The structure is simple, the design is novel, and the product has high reliability. A switch shaft 12 is provided diagonally below the camshaft 4 and is rotatably mounted in the mechanism housing 6 through a bearing 2. The cam 9, which is centrally mounted on the camshaft 4, is connected to the switch shaft 12. The crank arm rollers on the upper part are positioned correspondingly and move against each other when the camshaft 4 or the switch shaft 12 rotates. The output crank arm fixed in the center on the switch shaft 12 is connected to the input end of the four-bar linkage through a connecting plate. The camshaft 4 is equipped with a mechanism lever 5 for limiting the clockwise rotation of the switch shaft 12 when the switch is closed. During the closing process of the equipment, the mechanism lever 5, through cooperation with the switch shaft 12, can accurately limit its rotation angle, ensuring that the closing action is in place and does not rotate excessively, thereby ensuring the accuracy of the opening and closing actions. At the same time, the cooperation between the mechanism lever 5 and the camshaft 4 and the switch shaft 12 can reduce the mechanical wear caused by the action deviation, indirectly improving the overall reliability and service life of the equipment. The spring operating mechanism 7 keeps the latching parts uniformly using lever roller latching, reducing wear and ensuring reliability.

[0025] The mechanism housing 6 has a buffer device on its inner bottom surface for absorbing and buffering the energy on the switch shaft 12 during opening and closing processes. The buffer device includes an opening buffer 1 for absorbing excess energy during opening, a closing buffer 13 for absorbing excess energy during closing, and a positioning buffer 3 for absorbing the impact energy of opening and positioning the moving parts. The switch shaft 12 has crank arms at positions corresponding to the opening buffer 1, closing buffer 13, and positioning buffer 3, which contact the opening buffer when it is rotated to the correct position. Specifically, the opening buffer 1 and closing buffer 13 are rubber buffers, and the positioning buffer 3 is an oil buffer for opening and positioning. In the above structure, by setting up the buffer device, the energy impact during opening and closing processes can be effectively mitigated, the wear of mechanical parts can be reduced, and the stability and service life of the equipment can be improved.

[0026] like Figure 2As shown, the specific structure of the four-bar linkage is as follows: The four-bar linkage includes a transmission crank arm 14, a main connecting plate 18, and two main crank arms 20. Two crank arm supports 21 and a transmission crank arm support 23 are fixed on the bottom plate of the transmission box 15. The transmission crank arm 14 has a triangular plate structure. The corner of the intersection of the two short sides of the transmission crank arm 14 is hinged to one side of the transmission crank arm support 23, and one end of the transmission crank arm 14 is hinged to the output crank arm in the spring operating mechanism 7 through the connecting plate. One of the main crank arms 20 is hinged to the other side of the transmission crank arm support 23, and the upper end of the main crank arm 20 is concentrically hinged to one end of the output connecting plate 16 and the main connecting plate 18, while the lower end of the main crank arm 20 is hinged to one of the... The lower end of the tie rod 17 is connected to the transmission crank arm 14, and the other end of the transmission crank arm 14 is hinged to the other end of the output connecting plate 16. The other main crank arm 20 is hinged to the crank arm support 21 on the side away from the mechanism box 6, and the upper end of the main crank arm 20 is hinged to the other end of the main connecting plate 18, while the lower end of the main crank arm 20 is connected to the lower end of the other insulating tie rod 17. When the main connecting plate 18 moves back and forth, the two main crank arms 20 respectively control the up and down of the two insulating tie rods 17. A buffer crank arm 19 is provided in the middle of the two main crank arms 20 and is hinged to the other main crank arm 20. One end of the buffer crank arm 19 is hinged to the middle of the main connecting plate 18, and the other end of the buffer crank arm 19 is connected to the buffer 22 provided on the bottom plate of the transmission box 15.

[0027] Each phase switch has two parallel vacuum interrupters arranged before and after it. The moving end of the vacuum interrupter is connected to the main crank arm 20 through an insulating pull rod 17 with a contact spring, realizing the opening and closing movement of the interrupter. Its operating principle is as follows: The spring operating mechanism 7 installed on the mechanism box 6, driven by the energy storage motor 8, completes the energy storage process through the rotation of the camshaft 4. After receiving the closing command, the energy storage spring 10 releases energy to drive the camshaft 4 to rotate instantaneously, and the cam 9 installed on it strikes the corresponding position on the switch shaft 12. The rollers on the crank arm drive the switch shaft 12 to rotate clockwise until it stops at the limit position of the mechanism lever 5. The output crank arm of the switch shaft 12 drives the transmission crank arm 14, which is hinged to the transmission crank arm support 23 in the transmission box 15, to rotate clockwise through the connecting plate. Through the output connecting plate 16 and the main connecting plate 18, the main crank arm 20 and the buffer crank arm 19, which are hinged to the crank arm support 21, rotate clockwise. The insulating pull rod 17 connected to the other end of the main crank arm 20 will move upward, thereby driving the vacuum interrupter to achieve the closing action.

[0028] Upon receiving the tripping command, the mechanism lever 5 releases its limit. Under the action of the contact spring, the insulating pull rod 17 moves downward, causing the main crank arm 20 to rotate counterclockwise. This rotation is also transmitted through the main connecting plate 18 and the output connecting plate 16. The buffer crank arm 19, the output crank arm 14, and the switch shaft 12 move counterclockwise. The buffer crank arm 19 contacts the buffer 22, and the crank arm on the switch shaft 12 is limited by the tripping buffer 1 and the positioning oil buffer 3, thus completing the tripping action.

[0029] In this structure, the pumped storage switchgear consists of three single-phase switchgear units forming a three-phase box-type switchgear. Each single-phase switchgear unit is installed separately in a box, and the three boxes are arranged in parallel to form a complete three-phase switchgear. Each phase unit is equipped with a separate spring operating mechanism 7 and a four-bar linkage mechanism. Through electrical connection, three-phase mechanical linkage can be achieved. The overall structure is simple and compact.

[0030] The spring operating mechanism 7 and the four-bar linkage mechanism are designed for the operating conditions of the corresponding switchgear, requiring frequent operation and numerous starts, and thus possessing the characteristics of long life and high reliability. Given the small opening distance of the vacuum interrupter and the high contact pressure required by the contacts, the original three-phase integrated mechanism design was abandoned in favor of a three-phase compartmentalized structure. Following the principle of "mature equals stable, simple equals reliable," mechanical reliability studies were conducted on the characteristics of the equipment body, operating mechanism, transmission links, and matching interrupters. The current-carrying capacity and dynamic and thermal stability of the interrupters were analyzed, and the overall structure was optimized. Existing mature interrupters were selected, and a mature four-bar linkage mechanism was chosen for the transmission system. Further optimization of the spring mechanism was achieved through calculations of the equivalent mass of moving parts such as the vacuum interrupter and the closing work required during the closing process. Simulation of the transmission structure and stress analysis of key components ensured that the mechanism and transmission components met strength requirements.

[0031] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A complete set of switchgear for a pumped storage power station, characterized in that: The three-phase box-type switchgear includes three single-phase switchgear units that achieve three-phase mechanical linkage through electrical connection. The circuit breaker controlled by the single-phase switchgear unit is composed of two vacuum interrupters connected in parallel. The single-phase switchgear unit includes a transmission box (15) and a mechanism box (6) that are distributed and fixedly connected at the front and rear. A spring operating mechanism (7) is installed in the mechanism box (6). The output crank arm of the spring operating mechanism (7) is connected to the input end of the four-bar linkage mechanism located in the transmission box (15). The two output ends of the four-bar linkage mechanism are connected to the lower ends of the insulating pull rods (17) of the two vacuum interrupters of the corresponding phase circuit breaker. The opening and closing actions are completed with the cooperation of the spring operating mechanism (7) and the four-bar linkage mechanism.

2. The complete set of switchgear for a pumped storage power station according to claim 1, characterized in that: The spring operating mechanism (7) includes an energy storage motor (8), an energy storage spring (10), a camshaft (4), and a cam (9). The output end of the energy storage motor (8) is connected to the camshaft (4) rotatably installed in the mechanism box (6) through a gear transmission group (11). The lower ends of the two energy storage springs (10) symmetrically distributed on both sides of the camshaft (4) are connected to the corresponding ends of the camshaft (4). The camshaft (4) is provided with a switch shaft (12) rotatably installed in the mechanism box (6) through a bearing (2) at an angle below. The cam (9) installed in the center on the camshaft (4) corresponds to the position of the crank arm roller on the switch shaft (12) and moves against each other when the camshaft (4) or the switch shaft (12) rotates. The output crank arm fixed in the center on the switch shaft (12) is connected to the input end of the four-bar linkage through a connecting plate. The camshaft (4) is provided with a mechanism lever (5) for limiting the clockwise rotation of the switch shaft (12) when the switch is closed.

3. The complete set of switchgear for a pumped storage power station according to claim 2, characterized in that: The bottom surface of the mechanism box (6) is provided with a buffer device for absorbing and buffering the energy on the switch shaft (12) during the opening and closing process. The buffer device includes an opening buffer (1) for absorbing excess energy during the opening process, a closing buffer (13) for absorbing excess energy during the closing process, and a positioning buffer (3) for absorbing the opening impact energy and positioning the action part.

4. The complete set of switchgear for a pumped storage power station according to claim 3, characterized in that: The opening buffer (1) and closing buffer (13) are rubber buffers, and the positioning buffer (3) is an oil buffer for opening positioning.

5. The complete set of switchgear for pumped storage power station units according to any one of claims 1-4, characterized in that: The four-bar linkage includes a transmission crank arm (14), a main connecting plate (18), and two main crank arms (20). Two crank arm supports (21) and a transmission crank arm support (23) are fixed to the bottom plate of the transmission box (15). The transmission crank arm (14) has a triangular plate structure. The corner of the intersection of the two short sides of the transmission crank arm (14) is hinged to one side of the transmission crank arm support (23). One end of the transmission crank arm (14) is hinged to the output crank arm in the spring operating mechanism (7) via a connecting plate. One of the main crank arms (20) is hinged to the other side of the transmission crank arm support (23). The upper end of the main crank arm (20) is concentrically hinged to one end of the output connecting plate (16) and the main connecting plate (18), while the lower end of the main crank arm (20) is connected to the lower end of one of the insulating pull rods (17). The other end of the transmission crank arm (14) is hinged to the other end of the output connecting plate (16); another main crank arm (20) is hinged to the crank arm support (21) on the side away from the mechanism box (6), and the upper end of the main crank arm (20) is hinged to the other end of the main connecting plate (18), while the lower end of the main crank arm (20) is connected to the lower end of another insulating pull rod (17), and the two main crank arms (20) respectively control the two insulating pull rods (17) up and down when the main connecting plate (18) moves back and forth. A buffer crank arm (19) is provided in the middle position of the two main crank arms (20) and is hinged to the other main crank arm (20). One end of the buffer crank arm (19) is hinged to the middle of the main connecting plate (18), while the other end of the buffer crank arm (19) is connected to the buffer (22) provided on the bottom plate of the transmission box (15).

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