Plate heat exchanger with adjustable frame length for waste heat recovery
The adjustable frame length design solves the problem of mismatched anchor bolts during plate heat exchanger installation, enabling an efficient and stable installation process, avoiding on-site troubleshooting, and improving the equipment's adaptability and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-11
- Publication Date
- 2026-04-14
AI Technical Summary
During the installation of plate heat exchangers, mismatch between the anchor bolts embedded in the frame and the concrete base can lead to installation delays, increased costs, and even affect structural safety. In particular, when the center distance of the anchor bolts is inconsistent, it is necessary to drill holes and install reinforcement bars on site or re-pour the foundation.
Design a plate heat exchanger for waste heat recovery with adjustable frame length. By setting a fixed pressure plate, a movable pressure plate, columns, upper guide rods and lower guide rods, the columns are slidably connected using the upper and lower rod holes, and multi-level precise adjustment is achieved through the upper and lower adjustment holes. The position is fine-tuned by combining corner brackets and waist-shaped holes to ensure the fit between the frame and the pre-embedded bolts.
This improves the installation efficiency and stability of plate heat exchangers, avoids on-site drilling and rebar installation or foundation re-pouring, reduces construction difficulty and cost, and ensures the rigidity and stability of the equipment.
Smart Images
Figure CN224121777U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of heat exchanger technology, and in particular to a plate heat exchanger for waste heat recovery with adjustable frame length. Background Technology
[0002] A plate heat exchanger is a high-efficiency heat exchanger composed of a series of metal plates with a certain corrugated shape stacked together. Thin rectangular channels are formed between the various plates, through which heat exchange occurs. Plate heat exchangers are mainly classified into two types: frame type (detachable) and brazed type. Frame type plate heat exchangers are made of many stamped corrugated thin plates spaced at certain intervals, sealed around the edges with gaskets, and overlapped and pressed together by a frame and clamping screws. The four corner holes of the plates and gaskets form distribution and collection pipes for the fluid, while also effectively separating the hot and cold fluids, allowing them to flow in the channels on both sides of each plate, thus exchanging heat through the plates.
[0003] Currently, plate heat exchangers are fixedly installed on a concrete base by a frame. Anchor bolts are pre-embedded in the concrete base during the pouring process, and the frame of the plate heat exchanger is connected to the anchor bolts to complete the fixation.
[0004] The existing technology has at least the following problems: During the installation of plate heat exchangers, there is a common situation where the frame of the heat exchanger does not match the anchor bolts embedded in the concrete base. This situation can delay installation and increase costs, or even affect structural safety, requiring the bolts to be cut or the foundation to be re-poured. The most common problem is that the center distance between the anchor bolts and the center distance between the bolt holes in the frame are inconsistent, which prevents the equipment from being lowered for installation and requires on-site drilling and rebar installation or other methods to deal with the problem. Utility Model Content
[0005] This invention addresses the shortcomings of existing technologies by developing a plate heat exchanger for waste heat recovery with an adjustable frame length. This invention allows for adjustment of the frame length according to site conditions and facilitates on-site installation, effectively improving the installation efficiency and stability of the plate heat exchanger.
[0006] The technical solution of this utility model to solve the technical problem is as follows: a plate heat exchanger for waste heat recovery with adjustable frame length, including a fixed pressure plate, a movable pressure plate and a column. The movable pressure plate is disposed between the fixed pressure plate and the column. Heat exchange plates are provided between the movable pressure plate and the fixed pressure plate. It also includes a horizontally arranged upper guide rod and a lower guide rod. The top and bottom of the column are respectively provided with an upper rod hole and a lower rod hole. The top of the column is slidably disposed on the upper guide rod through the upper rod hole, and the bottom of the column is slidably disposed on the lower guide rod through the lower rod hole. The top of the column is detachably connected to the first end of the upper guide rod by bolts, and the bottom of the column is detachably connected to the first end of the lower guide rod by bolts. Angle brackets are provided at the bottom of both the fixed pressure plate and the column, and the angle brackets are provided with waist-shaped holes.
[0007] As an optimization, the first end of the upper guide rod is evenly provided with several sets of upper adjustment holes. Mounting plates are installed on the columns on both sides of the upper rod holes. The mounting plates have upper through holes, and bolts are installed in the upper through holes and corresponding upper adjustment holes. By setting the upper adjustment holes, which can cooperate with the upper through holes on the mounting plates, multi-level precise adjustment of the upper guide rod's extension length can be achieved, further expanding the frame's length adaptability range and better handling installation scenarios with different anchor bolt center distances. The mounting plates increase the contact area between the columns and the upper guide rod, improving the firmness of the bolt connection. The upper through holes provide installation positioning for the bolts.
[0008] As an optimization, the first end of the lower guide rod is evenly provided with several sets of lower adjustment holes, which correspond to the upper adjustment holes. A U-shaped steel is provided at the bottom of the lower guide rod holes, and a lower through hole is provided on the U-shaped steel. Bolts are installed in the lower through hole and the corresponding lower adjustment hole. By setting the lower adjustment holes, the lower guide rod and the upper guide rod can be adjusted synchronously, ensuring that the lengths of the upper and lower sides of the frame are consistent and that the columns are installed vertically. By setting the U-shaped steel, the contact area between the lower guide rod and the column can be increased, improving the stability of the lower guide rod installation. By setting the lower through hole, it can cooperate with the lower adjustment hole to achieve precise bolt installation, ensuring the reliability of the fixed position after the lower guide rod length adjustment.
[0009] As an optimization, the upper guide rod includes H-beams and T-beams. The web of the T-beams connects to the bottom flange of the H-beams, and mounting plates are set on both sides of the web of the H-beams. By using H-beams, the overall structural strength and load-bearing capacity of the upper guide rod can be improved, ensuring long-term stable operation of the equipment. The web of the T-beams can also be adapted to the mounting plates, facilitating on-site bolt connections. By using T-beams, their flange structure can provide stable support and positioning for the heat exchange fins, preventing displacement and shaking of the heat exchange fins. At the same time, it provides a smooth sliding track for the movable pressure plate, ensuring convenient movement of the movable pressure plate and facilitating the installation and removal of the heat exchange fins.
[0010] As an optimization, the top of the movable pressure plate is provided with an upper mounting groove, within which a U-shaped mounting bracket is installed. Rollers are mounted on the inner walls of both sides of the mounting bracket, and these rollers are positioned on the flanges of the T-shaped steel. The upper mounting groove provides installation space for the mounting bracket, accommodating the upper guide rod and allowing the movable pressure plate to fully compress the heat exchange fins. The U-shaped mounting bracket adapts to the structural form of the T-shaped steel, with the rollers positioned on both sides of the T-shaped steel flanges. The rollers significantly reduce the resistance during the movement of the movable pressure plate, accommodating the installation needs of heat exchange fins of varying numbers and thicknesses, improving installation and maintenance efficiency, and ensuring the smooth sliding of the movable pressure plate.
[0011] As an optimization, the bottom of the movable pressure plate is provided with a lower mounting groove, and the lower guide rod is set in the lower mounting groove, with a gap between the lower guide rod and the lower mounting groove. By setting the lower mounting groove, the lower guide rod can be accommodated in the groove, allowing the movable pressure plate to fully press the heat exchange fins; by providing a gap between the lower guide rod and the lower mounting groove, hard friction between the movable pressure plate and the lower guide rod can be avoided when sliding, reducing component wear and extending the service life of the equipment. At the same time, the reserved gap can accommodate U-shaped steel when the fins are fully loaded.
[0012] Compared with the prior art, the present invention has the following beneficial effects:
[0013] By setting fixed and movable pressure plates, a clamping structure for the heat exchanger fins can be formed, providing stable installation support and adapting to the installation needs of heat exchanger fins of different numbers and thicknesses. By setting columns, they can cooperate with the fixed pressure plates, upper guide rods, and lower guide rods to form the equipment frame, ensuring the rigidity and stability of the equipment structure and bearing the load after the heat exchanger fins are compressed. The upper and lower guide rods can bear the weight of the movable pressure plate and heat exchanger fins, providing smooth sliding guidance for the movable pressure plate while meeting the needs of frame length adjustment. They can also accommodate anchor bolts with positional deviations without requiring on-site drilling, rebar installation, or bolt cutting. The upper and lower rod holes enable a sliding connection with the columns, allowing flexible adjustment of the column position to actively adapt to the pre-embedded bolts when there are positional deviations. The use of angle brackets and slotted holes allows for flexible fixing of the fixed pressure plates and columns to the concrete base, enabling fine-tuning of the position when there are positional deviations in the pre-embedded bolts of the concrete base, improving the adaptability of the equipment installation. Attached Figure Description
[0014] Figure 1 This is a perspective view of one embodiment of the present utility model.
[0015] Figure 2 This is a front view of one embodiment of the present invention.
[0016] Figure 3 This is a perspective view of the column in one embodiment of the present invention.
[0017] Figure 4 for Figure 2 A cross-sectional view along the AA direction.
[0018] In the diagram: 1. Fixed pressure plate; 2. Movable pressure plate; 3. Column; 4. Heat exchange fins; 5. Fastening bolts; 6. Upper guide rod; 7. Lower guide rod; 8. Upper rod hole; 9. Lower rod hole; 10. Angle bracket; 11. Waist-shaped hole; 12. Upper adjustment hole; 13. Mounting plate; 14. Upper through hole; 15. Lower adjustment hole; 16. U-shaped steel; 17. Lower through hole; 18. I-beam; 19. T-shaped steel; 20. Upper mounting groove; 21. Mounting bracket; 22. Pulley; 23. Lower mounting groove. Detailed Implementation
[0019] To clearly illustrate the technical features of this solution, the present invention will be described in detail below through specific implementation methods and in conjunction with the accompanying drawings.
[0020] Example 1
[0021] Figures 1 to 4 As one embodiment of this utility model, such as Figures 1 to 4 As shown, a plate heat exchanger for waste heat recovery with an adjustable frame length includes a fixed pressure plate 1, a movable pressure plate 2, and a column 3. The movable pressure plate 2 is positioned between the fixed pressure plate 1 and the column 3. Heat exchange plates 4 are provided between the movable pressure plate 2 and the fixed pressure plate 1. The fixed pressure plate 1 is connected to the movable pressure plate 2 by fastening bolts 5. The plate also includes a horizontally arranged upper guide rod 6 and a lower guide rod 7. The top and bottom of the column 3 are respectively provided with upper rod holes 8 and lower rod holes 9. The top of the column 3 is slidably mounted on the upper guide rod 6 through the upper rod hole 8, and the bottom of the column 3 is slidably mounted on the lower guide rod 7 through the lower rod hole 9. The top of the column 3 is connected to the fixed pressure plate 1 by bolts 6 and 7. The first end of the upper guide rod 6 is detachably connected. The bottom of the column 3 is detachably connected to the first end of the lower guide rod 7 by bolts. The bottom of the fixed pressure plate 1 and the column 3 are both provided with corner brackets 10. The grounding end of the corner bracket 10 at the bottom of the fixed pressure plate 1 is provided with a round hole, which is used for initial positioning during installation. The grounding end of the corner bracket 10 at the bottom of the column 3 is provided with a waist-shaped hole 11. The second end of the upper guide rod 6 is detachably connected to the top of the fixed pressure plate 1 by bolts. The second end of the lower guide rod 7 is detachably connected to the bottom of the fixed pressure plate 1 by bolts. The top of the movable pressure plate 2 is slidably connected to the upper guide rod 6, and the bottom of the movable pressure plate 2 is slidably connected to the lower guide rod 7.
[0022] By setting up a fixed pressure plate 1, a movable pressure plate 2, and fastening bolts 5, an installation clamping structure for the heat exchanger 4 can be formed, providing stable installation support for the heat exchanger 4 and adapting to the installation requirements of heat exchanger 4 with different numbers and thicknesses. By setting up columns 3, they can cooperate with the fixed pressure plate 1, upper guide rod 6, and lower guide rod 7 to form the frame of the equipment, ensuring the rigidity and stability of the equipment structure and bearing the load after the heat exchanger 4 is pressed. By setting up fastening bolts 5, the clamping force of the movable pressure plate 2 can be ensured, ensuring the sealing effect between the heat exchanger 4 and preventing the leakage of hot and cold fluids from affecting the heat exchange efficiency. By setting up upper guide rods 6 and lower guide rods 7, the movable pressure plate 2 can withstand the load. The weight of plate 2 and heat exchange fin 4 provides a smooth sliding guide for the movable pressure plate 2, while also meeting the needs of frame length adjustment. It can match anchor bolts with positional deviations without the need for on-site drilling, rebar installation, or bolt cutting. By setting the upper rod hole 8 and lower rod hole 9, a sliding connection with the column 3 can be achieved. When the position of the pre-embedded bolts deviates, the position of the column 3 can be flexibly adjusted to actively adapt to the pre-embedded bolts. By setting the angle bracket 10 and waist-shaped hole 11, the pressure plate 1 and column 3 can be flexibly fixed to the concrete base. When the position of the pre-embedded bolts in the concrete base deviates, fine-tuning of the position can be performed, improving the adaptability of equipment installation.
[0023] like Figures 1 to 3 As shown, the column 3 is a channel steel, and the first end of the upper guide rod 6 is evenly provided with several sets of upper adjustment holes 12. The column 3 on both sides of the upper rod hole 8 is provided with a mounting plate 13. The mounting plate 13 is provided with an upper through hole 14. Bolts are provided in the upper through hole 14 and the corresponding upper adjustment hole 12. The mounting plate 13 is connected to the upper guide rod 6 by bolts. The center distance between the two semicircles of the waist-shaped hole 11 is equal to the center distance between the two sets of upper adjustment holes 12. When the deviation of the anchor bolt is within the distance range of the two adjacent sets of upper adjustment holes 12, the waist-shaped hole 11 can also ensure that it fits the anchor bolt. By setting the column 3 as a channel steel, the structural strength and bending resistance of the column 3 can be improved by utilizing the profile characteristics of the channel steel, so as to better bear the overall load of the equipment. At the same time, the groove side of the channel steel facilitates the fixing and disassembly of the corner bracket 10, reducing maintenance difficulty, and the back side of the groove facilitates the welding of the mounting plate 13. By setting the upper adjustment hole 12, it can cooperate with the upper through hole 14 on the mounting plate 13 to realize multi-level precise adjustment of the extension length of the upper guide rod 6, further expanding the length adaptation range of the frame and better coping with different anchor bolt center distances. By setting the mounting plate 13, the connection contact area between the column 3 and the upper guide rod 6 can be increased, improving the firmness of the bolt connection. By setting the upper through hole 14, the bolt can be positioned for installation.
[0024] like Figures 1 to 3As shown, the first end of the lower guide rod 7 is evenly provided with several sets of lower adjustment holes 15, which correspond to the upper adjustment holes 12. A U-shaped steel 16 is provided at the bottom of the lower rod hole 9, and a lower through hole 17 is provided on the U-shaped steel 16. Bolts are installed in the lower through hole 17 and the corresponding lower adjustment hole 15. The U-shaped steel 16 is connected to the lower guide rod 7 by bolts. By setting the lower adjustment holes 15, the lower guide rod 7 and the upper guide rod 6 can be adjusted synchronously in length, ensuring that the lengths of the upper and lower sides of the frame are consistent and that the column 3 is installed vertically. By setting the U-shaped steel 16, the contact area between the lower guide rod 7 and the column 3 can be increased, improving the stability of the lower guide rod 7 installation. By setting the lower through hole 17, it can cooperate with the lower adjustment hole 15 to achieve precise bolt installation, ensuring the reliability of the lower guide rod 7 after length adjustment.
[0025] like Figures 1 to 4 As shown, the upper guide rod 6 includes an I-beam 18 and a T-beam 19. The web of the T-beam 19 is connected to the center of the bottom flange of the I-beam 18. The I-beam 18 and the T-beam 19 are integrally formed. The upper adjustment hole 12 is provided on the web of the I-beam 18. The mounting plate 13 is provided on both sides of the web of the I-beam 18. The top and bottom of the heat exchange plate 4 are provided with slots. The top of the heat exchange plate 4 is set on the flange of the T-beam 19 through the slots, and the bottom of the heat exchange plate 4 is set on the lower guide rod 7 through the slots. By setting the I-beam 18, the overall structural strength and load-bearing capacity of the upper guide rod 6 can be improved, ensuring long-term stable operation of the equipment. The web of the T-beam 19 can also be adapted to the mounting plate 13, facilitating on-site bolt connection. By setting the T-beam 19, its flange structure can provide stable support and positioning for the heat exchanger 4, preventing the heat exchanger 4 from shifting or shaking. At the same time, it provides a smooth sliding track for the movable pressure plate 2, ensuring convenient movement of the movable pressure plate 2 and facilitating the installation and removal of the heat exchanger 4. By setting slots at the top and bottom of the heat exchanger 4, precise engagement between the heat exchanger 4 and the flange of the T-beam 19 and the lower guide rod 7 can be achieved.
[0026] like Figure 4 As shown, the top of the movable pressure plate 2 is provided with an upper mounting groove 20, and a mounting frame 21 is provided inside the upper mounting groove 20. The mounting frame 21 is U-shaped, and pulleys 22 are provided on the inner walls of both sides of the mounting frame 21. The two sets of pulleys 22 are respectively set on the flanges on both sides of the web of the T-shaped steel 19. By setting the upper mounting groove 20, installation space can be provided for the mounting frame 21 to accommodate the upper guide rod 6, so that the movable pressure plate 2 can fully press the heat exchange fins 4. By setting the U-shaped mounting frame 21, it can be adapted to the structural shape of the T-shaped steel 19, and the pulleys 22 can be arranged on both sides of the flanges of the T-shaped steel 19. By setting the pulleys 22, the resistance when the movable pressure plate 2 moves can be greatly reduced, adapting to the installation requirements of heat exchange fins 4 of different numbers and thicknesses, improving installation and maintenance efficiency, and ensuring the smooth sliding of the movable pressure plate 2.
[0027] like Figure 1 andFigure 4 As shown, the bottom of the movable pressure plate 2 is provided with a lower mounting groove 23, and the lower guide rod 7 is set in the lower mounting groove 23, with a gap between the lower guide rod 7 and the lower mounting groove 23. By setting the lower mounting groove 23, the lower guide rod 7 can be accommodated in the groove, so that the movable pressure plate 2 can fully press the heat exchange plate 4; by providing a gap between the lower guide rod 7 and the lower mounting groove 23, hard friction between the movable pressure plate 2 and the lower guide rod 7 can be avoided when they slide, reducing component wear and extending the service life of the equipment. At the same time, the reserved gap can accommodate the U-shaped steel 16 when the heat exchange plate 4 is fully loaded.
[0028] When using the equipment, after it arrives at the installation site, first measure the center distance of the anchor bolts embedded in the concrete base and compare it with the preset length when the equipment left the factory. Based on the measurement results, determine the required adjustment length of the upper guide rod 6 and the lower guide rod 7. Loosen the bolts on the mounting plate 13 and the U-shaped steel 16, slide the column 3 on the upper guide rod 6 and the lower guide rod 7, select a suitable set of upper adjustment holes 12 and align them with the upper through holes 14 of the mounting plate 13, and insert bolts for initial tightening. At this time, the corresponding lower adjustment hole 15 on the lower guide rod 7 is also aligned with the lower through hole 17 of the U-shaped steel 16, and bolts are inserted for initial tightening, completing the synchronous adjustment of the extension length of the upper guide rod 6 and the lower guide rod 7.
[0029] Using lifting equipment, the adjusted frame (including fixed pressure plate 1, movable pressure plate 2, column 3, upper guide rod 6 and lower guide rod 7) is lifted as a whole and slowly moved above the concrete base. The pre-embedded anchor bolts are aligned with the round holes of the bottom corner bracket 10 of the fixed pressure plate 1 and the oblong holes 11 of the bottom corner bracket 10 of the column 3. The round holes can enhance the stability of the equipment after installation, while the oblong holes 11 are designed so that even if there is a slight deviation in the bolt position (within the range of the first-level adjustment hole distance), they can be smoothly fitted in.
[0030] After the equipment is in place, check whether each corner bracket 10 is in stable contact with the base. Then tighten the nuts on the anchor bolts to firmly fix the fixing plate 1 and the column 3 to the concrete base. Then, tighten the bolts on the mounting plate 13 and the U-shaped steel 16 to ensure that the positions of the upper guide rod 6 and the lower guide rod 7 are completely locked, and the frame installation is completed.
[0031] Then, align the top slot of the first heat exchange plate 4 with the flange of the T-shaped steel 19 of the upper guide rod 6, and align its bottom slot with the lower guide rod 7. Push it along the guide rod towards the fixed pressure plate 1, and install the sealing gasket and subsequent heat exchange plates 4 in sequence until the designed number of plates is reached. Push the movable pressure plate 2 towards the heat exchange plate 4 through the pulley 22. Install several sets of fastening bolts 5, and gradually tighten all the heat exchange plates 4 by tightening the bolts to achieve the specified compression size and ensure reliable sealing between the plates.
[0032] This utility model, through the multi-level adjustable design of the upper guide rod 6 and the lower guide rod 7, and the fine-tuning function of the waist-shaped hole 11 of the corner code 10, successfully solves the common problem of mismatch between the center distance of the plate heat exchanger and the pre-embedded anchor bolts during installation. It eliminates the need for on-site cutting, rebar installation, or re-pouring of the foundation, greatly improving installation efficiency and adaptability, and reducing construction difficulty and cost.
[0033] The descriptions of the orientation or relative positional relationships of the structure in this utility model, such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inner", and "outer", are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the structure referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
Claims
1. A plate heat exchanger for waste heat recovery with adjustable frame length, comprising a fixed pressure plate (1), a movable pressure plate (2), and a column (3), wherein the movable pressure plate (2) is disposed between the fixed pressure plate (1) and the column (3), and heat exchange plates (4) are provided between the movable pressure plate (2) and the fixed pressure plate (1), characterized in that: It also includes a horizontally arranged upper guide rod (6) and lower guide rod (7). The top and bottom of the column (3) are respectively provided with an upper rod hole (8) and a lower rod hole (9). The top of the column (3) is slidably set on the upper guide rod (6) through the upper rod hole (8), and the bottom of the column (3) is slidably set on the lower guide rod (7) through the lower rod hole (9). The top of the column (3) is detachably connected to the first end of the upper guide rod (6) by bolts, and the bottom of the column (3) is detachably connected to the first end of the lower guide rod (7) by bolts. The bottom of the fixed pressure plate (1) and the column (3) are both provided with corner brackets (10), and the corner brackets (10) are provided with waist-shaped holes (11).
2. The plate heat exchanger for waste heat recovery with adjustable frame length according to claim 1, characterized in that: The first end of the upper guide rod (6) is evenly provided with several sets of upper adjustment holes (12). The columns (3) on both sides of the upper rod hole (8) are provided with mounting plates (13). The mounting plates (13) are provided with upper through holes (14). Bolts are provided in the upper through holes (14) and the corresponding upper adjustment holes (12).
3. The plate heat exchanger for waste heat recovery with adjustable frame length according to claim 2, characterized in that: The first end of the lower guide rod (7) is provided with several sets of lower adjustment holes (15), the lower adjustment holes (15) correspond to the upper adjustment holes (12), the bottom of the lower rod hole (9) is provided with a U-shaped steel (16), the U-shaped steel (16) is provided with a lower through hole (17), and the lower through hole (17) and the corresponding lower adjustment hole (15) are provided with bolts.
4. The plate heat exchanger for waste heat recovery with adjustable frame length according to claim 2, characterized in that: The upper guide rod (6) includes an I-beam (18) and a T-beam (19). The web of the T-beam (19) is connected to the bottom flange of the I-beam (18), and the mounting plate (13) is set on both sides of the web of the I-beam (18).
5. The plate heat exchanger for waste heat recovery with adjustable frame length according to claim 4, characterized in that: The top of the movable pressure plate (2) is provided with an upper mounting groove (20), and a mounting bracket (21) is provided in the upper mounting groove (20). The mounting bracket (21) is U-shaped, and pulleys (22) are provided on the inner walls on both sides of the mounting bracket (21). The pulleys (22) are set on the flanges of the T-shaped steel (19).
6. The plate heat exchanger for waste heat recovery with adjustable frame length according to any one of claims 1 to 5, characterized in that: The bottom of the movable pressure plate (2) is provided with a lower mounting groove (23), and the lower guide rod (7) is set in the lower mounting groove (23). There is a gap between the lower guide rod (7) and the lower mounting groove (23).