An inserted combined valve applied to the oil supply circuit of a pile hammer for offshore operations

Abstract

The present invention relates to a cartridge-type combined valve applied to the oil supply circuit of a pile hammer for offshore operations, which is composed of a pilot-stage cartridge valve and a main-stage cartridge valve. The pilot-stage cartridge valve is connected to the main-stage cartridge valve and is used to control the pressure of the control port of the main-stage cartridge valve. The pilot-stage cartridge valve is composed of an electromagnetic directional valve and a cartridge valve. The electromagnetic directional valve is controllably connected to the cartridge valve and is used to achieve flexible control and rapid response of the cartridge valve. The present invention applies a special combined cartridge valve with high pressure resistance, large flow rate, rapid response and impact resistance to an offshore pile hammer.

Description

Technical Field

[0001] The present invention relates to an oil inlet combination valve applied to a pile hammer for offshore operations, and more particularly to a cartridge type combination valve. Background Art

[0002] With the increasing depletion of natural resources, the effective exploitation and utilization of marine resources have been paid more and more attention. The emergence of offshore pile hammers has solved the main problems of offshore installation operations.

[0003] Currently, the control valves applied to pile hammers for offshore operations are mostly ordinary cartridge valves. For ordinary cartridge valves, their main disadvantages are as follows: 1. The maximum flow rate is limited. Due to the structural design of the cartridge valve, the external dimensions of the cartridge valve have always been relatively small, which directly affects the size of the valve port and the flow passage, thus directly limiting the flow rate. 2. The control accuracy of ordinary cartridge valves is relatively low, and its linearity is only good within a certain opening range. 3. The function is relatively single, mainly used to realize the on-off of the oil circuit. In view of the above disadvantages, a torque motor direct control type cartridge type two-dimensional electro-hydraulic proportional reversing valve (CN110131229B) patent introduced a highly integrated cartridge valve, and the spool can move in two degrees of freedom to achieve multi-dimensional on-off; a two-dimensional pilot-operated electromagnetic cartridge valve (CN111457127A) patent introduced a two-stage cartridge valve, the pilot stage is a micro electromagnetic switch valve, and the power stage is a cartridge valve. This valve has the advantages of low power consumption and fast response, but has the disadvantages of low pressure and small flow rate; a special high-quality cartridge type combination valve (main valve plus pilot valve) used in supporting the hydraulic system circuit annular valve group is the core hydraulic component of offshore hydraulic pile hammer equipment, and its performance requirements have characteristics such as high pressure resistance, large flow rate, fast response, and impact resistance. The special cartridge combination valve (main valve plus pilot valve) needs to deeply study its fast response, anti-impact structural characteristics and liquid resistance control mechanism.

[0004] In summary, the cartridge valve has the advantages of simple structure, small mass, large direct push driving force, etc., and has a broad application prospect. However, in terms of the current development situation, there is a lack of a special combined cartridge valve with high pressure resistance, large flow rate, fast response, and impact resistance for offshore pile hammers. Most of the current cartridge valves have small flow rates, are not suitable for high pressures, and have slow responses, and cannot meet the requirements of offshore pile hammers. Therefore, there is an urgent need for a special combined cartridge valve with high pressure resistance, large flow rate, fast response, and impact resistance to be applied to offshore pile hammers. Summary of the Invention

[0005] In order to overcome the deficiencies in the prior art, the present invention provides a cartridge type combination valve applied to the oil supply circuit of an offshore pile hammer.

[0006] To solve the above existing technical problems, the technical solution adopted by the present invention is as follows: An inserted combined valve applied to the oil supply circuit of a pile hammer for offshore operations, which is composed of a pilot-stage inserted valve and a main-stage inserted valve. The pilot-stage inserted valve is connected to the main-stage inserted valve and is used to control the pressure of the control port of the main-stage inserted valve. The pilot-stage inserted valve is composed of an electromagnetic reversing valve and an inserted valve. The electromagnetic reversing valve is controllably connected to the inserted valve and is used to achieve flexible control and rapid response of the inserted valve.

[0007] Furthermore, the main-stage inserted valve is composed of a valve sleeve, a valve core, a spring seat, a first cover plate, a spring, and a flow channel. The valve sleeve is fixedly connected to the first cover plate. The valve core is installed inside the valve sleeve. The spring is installed inside the valve core through the spring seat, and both ends of the spring are respectively connected to the valve core and the first cover plate. The first cover plate is provided with a flow channel. One end of the valve sleeve is provided with a main valve control port X, the other end is provided with a control port A, and the side is provided with a control port B. The control port A is communicated with the upper cavity B of the valve core through the flow channel.

[0008] Furthermore, the valve sleeve is provided with 8 circular oil inlets arranged along the circumference of the valve sleeve, and the bottom is provided with an oil outlet in the form of a conical surface. The top is connected to the first cover plate in the form of a threaded connection, and three sealing grooves are provided for installing sealing rings.

[0009] Furthermore, the valve core is a semi-empty cylindrical structure. The upper cavity is used to install the spring and control the entry of oil. The lower end has two conical surfaces, one of which is used to form an end face to realize the upward movement of the valve core, and the other is used to form a conical surface seal with the valve sleeve to isolate the oil inlet cavity and the oil outlet cavity. Multiple groups of annular grooves are opened on the outer surface for sealing and reducing the resistance of movement.

[0010] Furthermore, the first cover plate is used to connect the control oil to the upper cavity of the valve to control the opening and closing of the valve core. Two vertical oil channels are arranged inside to form four oil inlets, and at the same time, the oil is introduced into the inner cavity and the upper plane of the valve core. The oil inlet connection port is placed at the bottom of the first cover plate for connecting the valve block, and an oil drain joint is also provided on the side for safety purposes.

[0011] Furthermore, the spring seat is a hollow cylinder at the lower part, mainly used to place the spring to prevent the spring from deflecting and misaligning. The upper part is provided with a drilled hole for the flow channel; the spring has a right-handed helix, with a total of 16 turns and a stiffness of 116.3 N / mm.

[0012] Furthermore, the pilot-stage inserted valve includes a valve body, a valve seat, a second cover plate, an outer cover plate, a second valve core, a first valve core, a plug shaft, a valve sleeve, and a flow channel. The valve body contains the valve seat and the valve sleeve. The valve seat contains the first valve core, and the valve sleeve contains the second valve core. One end of the second valve core is connected to the second cover plate and the outer cover plate through the plug shaft. The valve body is provided with the P1 port, P2 port, A1 port, A2 port, A3 port, T2 port of the inserted valve, the D1, D2, and D3 ports of the electromagnetic reversing valve, and is provided with flow channels L1, L4, and L5.

[0013] Furthermore, the valve body is a stepped cylindrical structure with a hollow interior. The lower part is used to install the electromagnetic directional control valve and is provided with a connecting oil passage for introducing the hydraulic oil at port P into port D3, the hydraulic oil at port D2 into the bottom of the main spool to control the opening and closing of the main spool, and the hydraulic oil at port D1 back to port T2. The upper part is provided with port P, port T, port A1, port A2 and their flow passages, and the opening and closing of the cartridge valve is realized by the up and down movement of spool one in the valve sleeve.

[0014] Furthermore, spool one is of a cylindrical structure, and the control oil of the electromagnetic directional control valve flows to the lower end face of spool one through the internal oil passage, so as to realize the up and down movement of spool one; spool two is an irregular grooved cylinder, connected to spool one at the lower end, provided with two circular grooves in the middle for connecting port P and port A, and also provided with a groove at the top for connecting port T and port A.

[0015] Furthermore, the outer cover plate is used to fix spool two, and is provided with a threaded hole at the top, and is connected to cover plate two through bolts.

[0016] Furthermore, the valve seat is of a cylindrical structure, internally provided with four channels, two of which are used for supplying oil to spool one, and the other two are used for connecting port T to drain oil to the outside. In addition, the valve seat and spool one form a clearance fit; the upper end of the plug shaft is connected to the outer cover plate, and the lower end is connected to spool two, and is a guide groove for the movement of spool two.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The application of heat treatment technology and the reasonable selection of the materials of the main valve sleeve and the valve body optimize the spool valve sleeve structure, and improve the service life and impact resistance of the valve group.

[0019] 2. Optimize the design of the pilot valve liquid resistance bridge circuit, optimize the configuration of the pilot liquid resistance bridge circuit through motion simulation calculation, form a fast-response liquid bridge selection group, improve the response ability of the pilot stage, optimize the dynamic characteristics of the main valve, and lay a foundation for the transition zone window control of the fast-switching circuit.

[0020] 3. Use ANSYS to conduct stress simulation analysis on the combined valve, conduct multi-condition stress analysis through interaction to optimize the spool valve sleeve structure, use Fluent to conduct flow field simulation analysis through interaction to improve the structure and reduce the cavitation phenomenon, optimize the parts with excessive stress and excessive loss, and obtain a valve group with strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the schematic cross-sectional view of the main valve of the two-stage inlet combined cartridge valve of the present invention;

[0022] Figure 2 is the schematic cross-sectional view of the pilot valve of the two-stage inlet combined cartridge valve of the present invention;

[0023] Figure 3 is the hydraulic schematic diagram of the second-stage oil inlet combined cartridge valve of the present invention;

[0024] Figure 4 is the AMESIM simulation model diagram of the second-stage oil inlet combined cartridge valve of the present invention. Specific embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0027] As Figures 1 to 3 shown, a combined cartridge valve of a pilot valve and an oil inlet valve applied to an offshore operation pile hammer includes a pilot-stage cartridge valve D and a main-stage cartridge valve P. The pilot-stage cartridge valve D is connected to the main-stage cartridge valve P and is used to control the control port pressure of the cartridge valve PR. The pilot-stage cartridge valve D is composed of an electromagnetic reversing valve and a cartridge valve. The cartridge valve is controlled by the electromagnetic reversing valve to achieve flexible control and rapid response of the cartridge valve.

[0028] As Figure 1 shown, the main-stage cartridge valve is composed of a valve sleeve 1, a valve core 2, a spring seat 3, a first cover plate 4, a spring 5, and a flow channel. The valve sleeve 1 is fixedly connected to the first cover plate 4. The valve core 2 is installed in the valve sleeve 1. The spring 5 is installed in the valve core 2 through the spring seat 3, and both ends of the spring 5 are respectively connected to the valve core 2 and the first cover plate 4. A flow channel is provided in the first cover plate 4. One end of the valve sleeve 1 is provided with a main valve control port X, the other end is provided with a control port A, and the side is provided with a control port B. The control port A is communicated with the upper cavity B of the valve core through the flow channel.

[0029] Preferably, the valve sleeve 1 is provided with 8 circular oil inlets arranged along the circumference of the valve sleeve. The bottom is provided with an oil outlet in the form of a conical surface, and the top is connected to the end cover in the form of a threaded connection. Three sealing grooves are provided for installing sealing rings.

[0030] Preferably, the valve core 2 is mainly a semi-empty cylindrical structure. The upper cavity is mainly used for installing the spring 5 and controlling the entry of oil. The lower end has two conical surfaces. One of them is used to form an end surface to realize the upward movement of the valve core 2, and the other is used to form a conical seal with the valve sleeve 1 to isolate the oil inlet cavity and the oil outlet cavity. Multiple groups of annular grooves are opened on the outer surface, which can not only play a sealing role but also reduce the resistance of movement.

[0031] Preferably, the first cover plate 4 is mainly used to connect the control oil to the upper cavity of the valve to control the opening and closing of the control valve core 2. It is internally provided with two vertical oil channels, forming four oil inlets, and at the same time introducing the oil into the inner cavity and the upper plane of the valve core 2. The oil inlet connection port is placed at the bottom of the cover plate for connecting to the valve block, and an oil drain joint is also provided on the side to play a safety role.

[0032] Preferably, the spring seat 3 is a hollow cylinder at the lower part, mainly used to place the spring 5 to prevent the spring 5 from deflecting and misaligning. A flow channel is drilled at the upper part to meet the better inflow of the oil into the valve core.

[0033] Preferably, the spring 5 has a right-handed helix, with a total of 16 turns and a stiffness of 116.3 N / mm.

[0034] As Figure 2 shown, the pilot stage cartridge valve consists of an electromagnetic directional valve and a cartridge valve. It mainly includes a valve body 11, a valve seat 12, a second cover plate 13, an outer cover plate 14, a second valve core 15, a first valve core 16, a plug shaft 17, a valve sleeve 18 and a flow channel. The valve body 11 contains the valve seat 12 and the valve sleeve 18. The valve seat 12 contains the first valve core 16, and the valve sleeve 18 contains the second valve core 15. One end of the second valve core 15 is connected to the second cover plate 13 and the outer cover plate 14 through the plug shaft 17. The valve body 11 is provided with the P1 port, P2 port, A1 port, A2 port, A3 port, T2 port of the cartridge valve, the D1, D2 and D3 ports of the electromagnetic directional valve, and is provided with flow channels L1, L4, L5. The flow channel provided in the valve body 11 introduces the high-pressure oil at the P port into the electromagnetic directional valve. The flow channel in the valve sleeve 18 is used to introduce the oil flowing out of the electromagnetic directional valve to the bottom of the pilot valve core, thereby controlling the opening of the pilot valve core.

[0035] Preferably, the valve body 11 is a stepped cylindrical structure with a hollow interior. The lower half is used to install the electromagnetic directional valve, and a communicating oil channel is provided to introduce the hydraulic oil at the P port into the D3 port, and the hydraulic oil at the D2 port into the bottom of the main valve core to control the opening and closing of the main valve core, and the hydraulic oil at the D1 port is led back to the T2 port. The upper half is provided with the P port, T port, A1 port, A2 port and their flow channels. The opening and closing of the cartridge valve are realized by the up and down movement of the main valve core in the valve sleeve.

[0036] Preferably, the first valve core 16 is a cylindrical structure, and the control oil of the electromagnetic directional valve flows to the lower end face of the first valve core 16 through the internal oil channel, thereby realizing the up and down movement of the first valve core 16.

[0037] Preferably, the second valve core 15 is an irregular grooved cylinder, with the lower end connected to the first valve core 16, and two round grooves are provided in the middle to connect the P port and the A port, and at the same time a groove is also provided at the top for connecting the T port and the A port.

[0038] Preferably, the outer cover plate 14 is mainly used to fix the second valve core 15, and a threaded hole is provided at the top and is connected to the second cover plate 13 through a bolt.

[0039] Preferably, the valve seat 12 is also of a cylindrical structure with four channels provided inside. Two of them are used to supply oil to the first spool 16, and the other two are used to connect to the T port for draining oil to the outside. In addition, the valve seat 12 and the first spool form a clearance fit.

[0040] Preferably, the upper end of the plug shaft 17 is connected to the outer cover plate 14, and the lower end is connected to the second spool 15, serving as a guiding groove for the movement of the second spool 15.

[0041] As Figure 3 shown, it is a schematic diagram of a two-stage oil inlet cartridge valve applied to an offshore pile hammer. High-pressure oil enters the B port of the main valve and the P1 port of the pilot valve simultaneously. When the electromagnetic directional valve is de-energized and in the right position, the high-pressure oil cannot pass through the directional valve. Instead, the high-pressure oil passes through the damping hole to the left end of the pilot valve, and the oil at the right end returns to the oil tank. The pilot valve is in the left position, and the oil in the control port of the main valve returns to the oil tank through the pilot valve. Thus, the pressure at the B port lifts the main spool upward, causing the B port and the A port to communicate, and the high-pressure oil enters the pile hammer through the main valve. When the electromagnetic directional valve is energized, the valve moves to the left position, and the D3 port and the D2 port communicate. Due to the adjustability of the throttle orifice, the pressure at the right end of the pilot valve spool is higher than that at the left end, and the pilot valve moves to the right position, connecting the P2 port to the A3 port. High-pressure oil enters the control chamber of the main valve. Since the area of the B chamber of the main valve is small, the spool cannot move upward, and the A port and the B port are in a disconnected state.

[0042] As Figure 4 shown, it is a simulation diagram of the special combined valve for oil inlet. By setting the sizes of various dampings and selecting the matching scheme of the pilot hydraulic resistance, different response characteristic curves are obtained, thereby correcting the simulation models such as the flow field and structure of the special combined valve. In addition, the structural characteristic analysis of the two-stage oil inlet combined valve, the flow field characteristic analysis of the special combined valve, the stress simulation calculation analysis, and the structural optimization of key parts are also carried out. Multi-condition stress analysis is performed interactively to optimize the structures of the spool and valve sleeve. By designing and combining different throttle orifice shapes and quantities, a stress distribution diagram is obtained, and the optimal scheme is selected for the structural optimization of key parts such as the spool and valve sleeve. The flow field mainly includes the simulation and optimization of the valve port flow field, the simulation calculation of typical working conditions, and the structural optimization of key parts. The FLUENT software is used to perform the simulation analysis of the flow field to obtain the flow rate characteristics and steady-state hydrodynamic force of the valve port. The flow field simulation analysis is performed interactively to improve the structure and reduce the cavitation phenomenon, providing a reference for its structural design. Through the matching of hydraulic resistance, structural analysis, and flow field analysis, the response of the special combined valve for oil inlet is further improved, and the pressure loss is further reduced.

[0043] The working process of the present invention is as follows:

[0044] (1) The oil inlet process of the special combined valve for oil inlet

[0045] High-pressure oil enters port B of the main valve and port P1 of the pilot valve simultaneously. When the solenoid valve is de-energized and in the right position, the high-pressure oil entering the pilot valve cannot pass through the directional valve. At this time, the spool of the pilot valve does not move, and the oil in the control port X of the main valve passes through port A3, then through the flow passage L1 of the pilot valve to port T2, and thus returns to the fuel tank. Since the pressure in the control port of the main valve is the back pressure, which is much lower than the inlet pressure, the pressure at port B pushes the main spool upward, causing it to move upward, so that port B and port A are connected, and the high-pressure oil enters the pile hammer through the main valve.

[0046] (2) Oil cut-off process of the dedicated combined valve for oil inlet

[0047] After the oil passes through port P1 of the pilot valve, it is divided into two paths. One path acts on the main spool of the pilot valve, and the other path reaches port D3 of the electromagnetic directional valve of the pilot valve through flow passage L2. At this time, the electromagnetic directional valve is energized, and the oil passes through port D2 of the electromagnetic directional valve and acts on the bottom of the pilot valve spool through flow passage L4, pushing the spool two upward, thereby driving the spool one to move. At this time, the oil in the main flow passage of the pilot valve passes through the valve sleeve and the spool to port A1, and reaches the control port X of the main valve through the main valve flow passage L5, causing the pressure in the upper chamber of the main valve to rise and approach the pressure at port B. Since the area of chamber B of the main valve is small, the spool cannot move upward, and port A and port B are in a disconnected state.

[0048] In this specification, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An inserted combined valve applied to the oil supply circuit of a pile hammer for offshore operations, characterized in that: It is composed of a pilot-stage cartridge valve and a main-stage cartridge valve. The pilot-stage cartridge valve is connected to the main-stage cartridge valve and is used to control the pressure of the control port of the main-stage cartridge valve. The pilot-stage cartridge valve is composed of an electromagnetic directional valve and a cartridge valve. The electromagnetic directional valve is controllably connected to the cartridge valve to achieve flexible control and rapid response of the cartridge valve. The main-stage cartridge valve is composed of a valve sleeve, a valve core, a spring seat, a first cover plate, a spring and a flow channel. The valve sleeve is fixedly connected to the first cover plate. The valve core is installed inside the valve sleeve. The spring is installed inside the valve core through the spring seat, and both ends of the spring are respectively connected to the valve core and the first cover plate. The first cover plate is provided with a flow channel. One end of the valve sleeve is provided with a main valve control port X, the other end is provided with a control port A, and the side is provided with a control port B. The control port A is communicated with the upper cavity B of the valve core through the flow channel. The pilot-stage cartridge valve includes a valve body, a valve seat, a second cover plate, an outer cover plate, a second valve core, a first valve core, a plug shaft, a valve sleeve and a flow channel. The valve body is internally provided with the valve seat and the valve sleeve. The first valve core is installed inside the valve seat. The second valve core is installed inside the valve sleeve. One end of the second valve core is connected to the second cover plate and the outer cover plate through the plug shaft. The valve body is provided with a P1 port, a P2 port, an A1 port, an A2 port, an A3 port, a T2 port of the cartridge valve, D1, D2 and D3 ports of the electromagnetic directional valve, and is provided with flow channels L1, L4 and L5.

2. The cartridge-type combined valve applied to the oil supply circuit of a pile hammer for offshore operations according to claim 1, characterized in that: The valve sleeve is provided with 8 circular oil inlets arranged along the circumference of the valve sleeve. The bottom is provided with an oil outlet in the form of a conical surface. The top is connected to the first cover plate in the form of a threaded connection and is provided with three sealing grooves for installing sealing rings.

3. The cartridge-type combined valve applied to the oil supply circuit of a pile hammer for offshore operations according to claim 1, characterized in that: The valve core is a semi-empty cylindrical structure. The upper cavity is used to install the spring and control the entry of hydraulic oil. The lower end has two conical surfaces. One is used to form an end face to realize the upward movement of the valve core, and the other is used to form a conical surface seal with the valve sleeve to isolate the oil inlet cavity and the oil outlet cavity. Multiple groups of annular grooves are opened on the outer surface for sealing and reducing the resistance of movement.

4. The cartridge-type combined valve applied to the oil supply circuit of a pile hammer for offshore operations according to claim 1, characterized in that: The first cover plate is used to connect the control oil to the upper cavity of the valve to control the opening and closing of the valve core. Two vertical oil channels are arranged inside to form four oil inlets. At the same time, the oil is introduced into the inner cavity and the upper plane of the valve core. The oil inlet connection port is placed at the bottom of the first cover plate for connecting the valve block. An oil drain joint is also arranged on the side to play a safety role.

5. The cartridge-type combined valve applied to the oil supply circuit of a pile hammer for offshore operations according to claim 1, characterized in that: The spring seat is a hollow cylinder at the lower part, mainly used to place the spring to prevent the spring from deflecting and misaligning. The upper part is provided with a drilled hole for the flow channel. The spring has a right-handed helix, with a total of 16 turns and a stiffness of 116.3 N / mm.

6. The cartridge-type combined valve applied to the oil supply circuit of a pile hammer for offshore operations according to claim 1, characterized in that: The valve body is a stepped cylindrical structure with a hollow inside. The lower half is used to install the electromagnetic directional valve and is provided with a communicating oil channel for introducing the hydraulic oil at the P port into the D3 port, and the hydraulic oil at the D2 port into the bottom of the main valve core to control the opening and closing of the main valve core. The hydraulic oil at the D1 port is led back to the T2 port. The upper half is provided with a P port, a T port, an A1 port, an A2 port and their flow channels. The opening and closing of the cartridge valve are realized by the up and down movement of the first valve core in the valve sleeve.

7. The cartridge-type combined valve applied to the oil supply circuit of a pile hammer for offshore operations according to claim 1, wherein: The spool 1 has a cylindrical structure. The control oil of the electromagnetic directional valve flows to the lower end face of the spool 1 through the internal oil passage, so as to realize the up and down movement of the spool 1; the spool 2 is an irregular grooved cylinder, the lower end is connected to the spool 1, two circular grooves are arranged in the middle to connect the P port and the A port, and at the same time, a groove is also arranged at the top for connecting the T port and the A port; the outer cover plate is used to fix the spool 2, and a threaded hole is arranged at the top, and it is connected to the cover plate 2 through a bolt.

8. The cartridge-type combined valve applied to the fuel supply circuit of a pile hammer for offshore operations according to claim 1, characterized in that: The valve seat has a cylindrical structure, and four channels are arranged inside. Two of them are used to supply oil to the spool 1, and the other two are used to connect the T port to drain oil to the outside. In addition, the valve seat and the spool 1 form a clearance fit; the upper end of the plug shaft is connected to the outer cover plate, and the lower end is connected to the spool 2, which is a guide groove for the movement of the spool 2.

Images