Screen window slideway with positioning structure and screen window

By introducing the design of rotating top block, sliding rod, first spring and anti-fall assembly into the screen slide, the problem of fast wear and laborious operation of the screen snaps is solved, and the stable hovering and smooth decline of the screen is achieved.

CN119434826AInactive Publication Date: 2025-02-14FOSHAN WANHEYUAN BUILDING MATERIALS CO LTD
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Patent Information

Application Number
CN202510017529.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-01-06
Publication Date
2025-02-14
Estimated Expiration
Not applicable · inactive patent

AI Technical Summary

Technical Problem

The existing screen buckles have problems such as fast wear of friction block structures and difficulty in lifting and unstable during falling.

Method used

A screen slide with a positioning structure is designed, including a rotating top block, a sliding rod, a first spring and a fall-proof assembly. The weight of the screen is distributed by the rotating top block and a sliding rod, and the resilience force of the first spring is used to stabilize the hover. And prevent the screen window from falling down quickly through the anti-fall assembly.

Benefits of technology

It improves the operation convenience when the screen is raised and the stability when it is lowered, extends the service life of the first spring, and effectively prevents noise or damage caused by rapid drop of the screen.

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Abstract

The invention discloses a screen window slideway with a positioning structure and a screen window, and relates to the technical field of screen windows. The screen window slideway with the positioning structure comprises a window frame, the screen window is connected in the window frame in a sliding mode, the screen window slideway further comprises two installation blocks which are transversely symmetrical, the two installation blocks which are transversely symmetrical are fixedly connected to the two transverse sides of the top end of the screen window, fixing rods are fixedly connected to the installation blocks, and rotating top blocks are rotationally connected to the fixing rods. When the screen window slides upwards, the window frame extrudes the end, away from the fixing rod, of the rotating ejector block, the rotating ejector block can be pushed in a more labor-saving mode to swing inwards to compress the first spring, and the screen window can be pushed upwards in a more labor-saving mode; the resilience force of the first spring bears the other part of weight of the screen window, so that the screen window can slide downwards more stably, the burden of the first spring can be relieved by sharing the weight of the screen window, and aging of the first spring is relieved.
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Description

Technical Field

[0001] The invention relates to the technical field of screen windows, and in particular to a screen window slideway and a screen window with a positioning structure. Background Art

[0002] In modern architecture and home decoration, screens are widely used as important protection and ventilation facilities. In order to meet the growing demand of users for the convenience and stability of screen operation, a variety of screen slides and screen systems with positioning structures have appeared on the market. These systems can achieve the suspension of screen fans at any position during the lifting and lowering process. However, the existing screen buckles (commonly known as free stop accessories) have some limitations, which are mainly reflected in the following two types: The screen buckle with friction block structure relies on friction to prevent the screen from sliding down, and achieves the hovering function by increasing the friction resistance between the screen and the guide rail. However, due to wear caused by long-term use, the effectiveness of the friction block will gradually decrease, and may eventually cause the screen to be unable to hover stably. In addition, this design is less adaptable to situations where the screen area is large or the weight is heavy, so it is not common in actual applications.

[0003] The spring-structured screen buckle relies on a built-in spring to offset the weight of the screen itself. By pre-compressing or stretching the spring, the screen can reach an approximate equilibrium state at any position, thereby achieving stable hovering. Although this solution solves the problem of friction block buckles to a certain extent, there are still some problems in actual use. First, when the user tries to push the screen upward, the dual resistance of the screen's own gravity and the spring elastic force must be overcome, which makes the pushing process very laborious. Secondly, when the screen is pulled downward, due to the combined effect of the screen's own weight and the user's pulling force, the screen will drop rapidly, resulting in an unstable descent process, and it is easy to collide with the window frame due to inertia, causing noise and damage. In addition, bearing the weight of the screen for a long time will cause the spring to age, especially when the screen is large and heavy, which will seriously affect the hovering effect and the service life of the system.

[0004] In view of the above problems, the present invention proposes a screen window slide and a screen window with a positioning structure. The device can improve the operating convenience when the screen window is lifted and the stability when it is lowered. Summary of the invention

[0005] In order to overcome the shortcomings of the existing screen buckles with friction block structure that are easy to wear, and the screen buckles with spring structure that are laborious when lifted and unstable when lowered, the present invention provides a screen slide and screen with a positioning structure, which can improve the operating convenience when lifting the screen and the stability when lowering it.

[0006] The technical implementation scheme of the present invention is: a screen slide and screen with a positioning structure, including a window frame, a screen slidingly connected in the window frame, and two transversely symmetrical mounting blocks, the two transversely symmetrical mounting blocks are fixedly connected to the transverse sides of the top end of the screen, a fixing rod is fixedly connected to the mounting block, a rotating top block is rotatably connected to the fixing rod, the rotating top block is arranged inclined as a whole, the bottom end of the rotating top block contacts the inner wall of the window frame, two transversely symmetrical sliding rods are slidably connected to the screen, the outer end of the sliding rod is movably connected to the adjacent rotating top block, a connecting piece is fixedly connected to the sliding rod, a first spring is connected between the connecting piece and the screen, the first spring is sleeved on the sliding rod, an anti-falling component is provided on the window frame and the screen, the anti-falling component is used to prevent the screen from falling suddenly, and a locking component is provided on the screen to prevent children and pets from opening it by mistake.

[0007] More preferably, the anti-fall component includes two laterally symmetrical locking rods, which are fixedly connected to the two lateral sides of the screen window. An inclined groove is opened in the middle of the two lateral sides of the screen window, and the locking rods are located in the inclined groove. Two laterally symmetrical sliding blocks are slidably connected to the window frame, a second spring is connected between the sliding block and the window frame, and an intercepting plate is fixedly connected to the sliding block.

[0008] More preferably, a side of the intercepting plate close to the locking rod is provided with equidistantly distributed protrusions for intercepting and clamping the locking rod.

[0009] More preferably, the locking assembly includes two laterally symmetrical guide plates, the two laterally symmetrical guide plates are fixedly connected to the screen window, a sliding plate is slidably connected between the two guide plates, an adjusting rod is rotatably connected to the screen window, the adjusting rod and the sliding plate are threadedly connected, two laterally symmetrical rubber limit blocks are slidably connected to the top of the screen window, a contact block is fixedly connected to the rubber limit block, and a spring is connected between the rubber limit block and the screen window.

[0010] More preferably, both lateral ends of the sliding plate are provided with upwardly bent protrusions, the side of the contact block close to the sliding plate is inclined, and the sliding plate and the contact block are pressed and matched.

[0011] More preferably, it also includes a cleaning component for cleaning impurities in the window frame slide, the cleaning component includes two vertically symmetrical fixed shafts, the two vertically symmetrical fixed shafts are fixedly connected to the mounting block, a cleaning wheel is rotatably connected to the fixed shaft, and cleaning brushes are fixedly connected on both sides of the top and bottom ends of the mounting block, and the cleaning brushes are in contact with adjacent cleaning wheels.

[0012] More preferably, it also includes a cleaning component for cleaning the cleaning wheel and the cleaning brush, the cleaning component includes two laterally symmetrical piston plates, the two laterally symmetrical piston plates are slidably connected to the screen window, air cavities are opened on both lateral sides of the screen window, the lower space of the air cavity is large, and the upper space is narrow, the air cavity is connected to the mounting block, the piston plate is located in the lower space of the air cavity, the bottom end of the piston plate is fixedly connected to a contact rod, the bottom end of the contact rod passes through the outside of the screen window, a third spring is connected between the piston plate and the screen window, and the third spring is sleeved on the contact rod.

[0013] Compared with the prior art, the present invention has the following advantages: 1. When the screen window slides upward, the window frame squeezes the end of the rotating top block away from the fixed rod, which can push the rotating top block to swing inward to compress the first spring with less effort, thereby offsetting the elastic force of the first spring, so that the screen window can be pushed upward with less effort; when the screen window slides downward, the rotating top block with the lower end tilted outward will play a role similar to that of a barb, with the rotating top block and the fixed rod bearing part of the weight of the screen window, and the rebound force of the first spring bearing another part of the weight of the screen window, so that the screen window can slide downward more smoothly, and sharing the weight of the screen window can reduce the burden of the first spring and slow down the aging of the first spring.

[0014] 2. If the screen window falls rapidly, the locking rod will move backwards due to inertia and come into contact with the protrusion on the interception plate. The protrusion will intercept and clamp the locking rod, thereby intercepting the screen window. This can effectively prevent the screen window from falling down and colliding with the window frame, causing noise or damage.

[0015] 3. After the rubber limit block slides outward and sticks to the inner wall of the window frame, the screen window can be locked in a designated position to prevent children or pets from opening the screen window and causing safety hazards.

[0016] 4. Clean the dust and impurities in the window frame by rotating the cleaning wheels on the upper and lower sides to ensure the supporting effect of the rotating top block and the window frame on the screen window.

[0017] 5. The piston plate slides upward to squeeze the air in the large space at the bottom of the air cavity into the small space at the top. The air in the small space at the top of the air cavity rushes into the mounting block, thereby cleaning the cleaning wheel and the cleaning brush to prevent dust and impurities from staying near the cleaning wheel and the cleaning brush. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0019] Figure 2 It is a schematic diagram of the cross-sectional structure of the present invention.

[0020] Figure 3 It is a schematic diagram of the enlarged three-dimensional structure of part A of the present invention.

[0021] Figure 4 It is a three-dimensional structural schematic diagram of the screen window, locking rod, interception plate and other components of the present invention.

[0022] Figure 5 It is a three-dimensional structural schematic diagram of the locking rod, the inclined groove and the sliding block and other components of the present invention.

[0023] Figure 6 It is a schematic diagram of the three-dimensional structure of the sliding block, the second spring, the intercepting plate and other components of the present invention.

[0024] Figure 7 It is a three-dimensional structural schematic diagram of components such as the rubber limit block, the contact block and the spring piece of the present invention.

[0025] Figure 8 It is a schematic diagram of the enlarged three-dimensional structure of part B of the present invention.

[0026] Fig. 9 It is a schematic diagram of the three-dimensional structure of the mounting block, the fixed shaft, the cleaning wheel and the cleaning brush of the present invention.

[0027] Fig.10 It is a three-dimensional structural schematic diagram of the air cavity, piston plate, contact rod and other components of the present invention.

[0028] Fig.11 It is a three-dimensional structural schematic diagram of the air cavity, screen window, mounting block and cleaning brush of the present invention.

[0029] The markings of the components in the accompanying drawings are as follows: 1. window frame, 2. screen window, 3. mounting block, 301. fixed rod, 4. rotating top block, 5. sliding rod, 501. connecting plate, 6. first spring, 7. locking rod, 701. inclined groove, 8. sliding block, 9. second spring, 10. intercepting plate, 11. guide plate, 12. sliding plate, 13. adjusting rod, 14. rubber limit block, 141. contact block, 142. spring, 15. fixed shaft, 16. cleaning wheel, 17. cleaning brush, 18. piston plate, 19. contact rod, 20. third spring, 21. air cavity. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Embodiment 1: A screen window slideway and screen window with a positioning structure, such as Figure 1 , Figure 2 and Figure 3As shown, it includes a window frame 1, a screen 2, a mounting block 3, a fixed rod 301, a rotating top block 4, a sliding rod 5, a connecting piece 501, a first spring 6, an anti-falling component and a locking component. The lower part of the window frame 1 is slidably connected to the screen 2, the upper positions on the left and right sides of the screen 2 are fixedly connected to the mounting blocks 3, the upper part of the mounting block 3 is fixedly connected to the fixed rod 301, the fixed rod 301 is rotatably connected to the rotating top block 4, the rotating top block 4 is arranged obliquely as a whole, the lower end of the rotating top block 4 contacts the inner wall of the window frame 1, the left and right parts of the upper part of the screen 2 are slidably connected to the sliding rod 5, the outer end of the sliding rod 5 is movably connected to the adjacent rotating top block 4, the sliding rod 5 is fixedly connected to the connecting piece 501, the first spring 6 is connected between the connecting piece 501 and the screen 2, the first spring 6 is sleeved on the sliding rod 5, the window frame 1 and the screen 2 are provided with an anti-falling component, the anti-falling component is used to prevent the screen 2 from falling suddenly, and the screen 2 is provided with a locking component for preventing children and pets from opening by mistake.

[0032] When the screen window 2 is pushed to slide upward, the mounting block 3, the fixing rod 301 and the rotating top block 4 will also move upward. At this time, the force applied by the window frame 1 on the rotating top block 4 is downward, and the window frame 1 squeezes the rotating top block 4 away from the end position of one end of the fixing rod 301, which can more effortlessly push the rotating top block 4 to swing inward and compress the first spring 6, thereby offsetting the elastic force of the first spring 6, so that the screen window 2 can be pushed upward more effortlessly. When the screen window 2 is pulled to slide downward, the force applied by the window frame 1 on the rotating top block 4 is upward. At this time, the rotating top block 4 with the lower end tilted outward will play a role similar to that of a barb. The rotating top block 4 transmits part of the weight of the screen window 2 to the fixing rod 301, and part of the weight of the screen window 2 is borne by the rotating top block 4 and the fixing rod 301, while the resilience of the first spring 6 bears The first spring 6 can also be used to lift the screen window 2 and lower the screen window 2 to a certain extent, thereby preventing the screen window 2 from sliding downward and colliding with the window frame 1 to cause noise or damage.

[0033] like Figure 4 , Figure 5 and Figure 6As shown, the anti-falling assembly includes a locking rod 7, a sliding block 8, a second spring 9 and an intercepting plate 10. The middle parts of the left and right sides of the screen window 2 are slidably connected with the locking rod 7. The middle parts of the left and right sides of the screen window 2 are provided with an inclined groove 701. The locking rod 7 is located in the inclined groove 701. The left and right parts of the window frame 1 are slidably connected with the sliding blocks 8. The second spring 9 is connected between the sliding block 8 and the window frame 1. The front side of the sliding block 8 is fixedly connected with the intercepting plate 10. The front side of the intercepting plate 10 is provided with equidistantly distributed protrusions for intercepting and clamping the locking rod 7.

[0034] In the initial state, the locking rod 7 and the protrusion on the intercepting plate 10 are in a misaligned state. When the screen window 2 slides up and down and drives the locking rod 7 to move up and down, the locking rod 7 will not contact the protrusion on the intercepting plate. If the screen window 2 falls rapidly, the locking rod 7 will slide backward and upward in the inclined groove 701 under the action of inertia. After moving backward, the locking rod 7 will contact the protrusion on the intercepting plate 10, and the locking rod 7 will be intercepted and stuck by the protrusion, thereby intercepting the screen window 2. Under the action of the expansion and contraction of the second spring 9 The sliding block 8 and the intercepting plate 10 can slide downward, thereby buffering the downward impact force of the screen window 2 and the locking rod 7, avoiding damage caused by the hard interception of the locking rod 7 and the protrusions on the intercepting plate 10. When the screen window 2 is stopped, the work is such as pushing the screen window 2 to slide upward, the locking rod 7 will be stuck on the protrusion on the intercepting plate 10, and the inclined groove 701 can squeeze the locking rod 7 to move forward and reset it to be misaligned with the protrusion on the intercepting plate. In this way, the screen window 2 can be effectively prevented from falling downward and colliding with the window frame 1 to cause noise or damage.

[0035] like Figure 1 , Figure 7 and Figure 8 As shown, the locking assembly includes a guide plate 11, a sliding plate 12, an adjusting rod 13, a rubber limit block 14, a contact block 141 and a spring piece 142. Two left-right symmetrical guide plates 11 are fixedly connected to the upper front side of the screen window 2, and a sliding plate 12 is slidably connected between the left and right guide plates 11. An adjusting rod 13 is rotatably connected to the middle and upper front side of the screen window 2. The adjusting rod 13 is connected to the sliding plate 12 by threads. The left and right parts of the upper side of the screen window 2 are both slidably connected to rubber limit blocks 14. The front side of the rubber limit block 14 is fixedly connected to the contact block 141. The left and right ends of the sliding plate 12 are provided with upwardly bent protrusions. The side of the contact block 141 close to the sliding plate 12 is inclined. The sliding plate 12 is squeezed and matched with the contact block 141. A spring piece 142 is connected between the rubber limit block 14 and the screen window 2.

[0036] When it is necessary to lock the screen window 2 to prevent children or pets from opening it by mistake, the staff rotates the adjusting rod 13, and the sliding plate 12 driven by the adjusting rod 13 slides upward, and the sliding plate 12 slides upward to squeeze the contact block 141 to move outward, and the contact block 141 moves outward to drive the rubber limit block 14 to slide outward, and the spring piece 142 is deformed. After the rubber limit block 14 slides outward, it is close to the inner wall of the window frame 1, and then the screen window 2 is locked in the specified position to prevent children or pets from opening the screen window 2 and causing safety hazards. When the screen window 2 needs to be opened and closed normally, the staff controls the adjusting rod 13 to reverse, and the adjusting rod 13 reverses to drive the sliding plate 12 to slide downward and no longer squeeze the contact block 141. At this time, the spring piece 142 is reset to drive the rubber limit block 14 and the contact block 141 to move inward and reset.

[0037] Embodiment 2: Based on embodiment 1, Fig. 9 As shown, a cleaning component for cleaning impurities in the slideway of the window frame 1 is also included, and the cleaning component includes a fixed shaft 15, a cleaning wheel 16 and a cleaning brush 17. The upper and lower parts of the mounting block 3 are fixedly connected to the fixed shaft 15, and the cleaning wheel 16 is rotatably connected to the fixed shaft 15. The cleaning brush 17 is fixedly connected to the upper and lower sides of the mounting block 3, and the cleaning brush 17 is in contact with the adjacent cleaning wheel 16.

[0038] When the device is used, when the screen window 2 drives the mounting block 3 to move up and down, the fixed shaft 15 and the cleaning wheel 16 will also move up and down together, and the dust and impurities in the window frame 1 are cleaned by the cleaning wheels 16 on the upper and lower sides to ensure the supporting effect of the rotating top block 4 and the window frame 1 on the screen window 2. When the cleaning wheel 16 rotates, the cleaning brush 17 can also clean the dust attached to the cleaning wheel 16 to prevent the dust attached to the cleaning wheel 16 from affecting the cleaning effect.

[0039] like Fig.10 and Fig.11 As shown, it also includes a cleaning component for cleaning the cleaning wheel 16 and the cleaning brush 17, the cleaning component includes a piston plate 18, a contact rod 19 and a third spring 20, the left and right parts of the screen 2 are slidably connected with the piston plate 18, the left and right parts of the screen 2 are opened with air cavities 21, the lower space of the air cavity 21 is large, and the upper space is narrow, the upper part of the air cavity 21 is connected with the mounting block 3, the piston plate 18 is located in the lower space of the air cavity 21, the lower side of the piston plate 18 is fixedly connected with the contact rod 19, the lower end of the contact rod 19 passes through the outside of the screen 2, the third spring 20 is connected between the piston plate 18 and the screen 2, and the third spring 20 is sleeved on the contact rod 19.

[0040] When using the device, the up and down movement of the screen 2 will also drive the piston plate 18 and the contact rod 19 to move up and down. When the contact rod 19 moves downward to contact the window frame 1, the contact rod 19 is squeezed by the window frame 1, causing the piston plate 18 to slide upward in the air cavity 21, and the third spring 20 is deformed. The piston plate 18 slides upward to squeeze the air in the large space at the bottom of the air cavity 21 into the small space at the top. The air in the small space at the top of the air cavity 21 rushes into the mounting block 3, and then the cleaning wheel 16 and the cleaning brush 17 are cleaned to prevent dust and impurities from staying near the cleaning wheel 16 and the cleaning brush 17. When the screen 2 slides upward, the contact rod 19 is no longer squeezed by the window frame 1. Under the action of the resetting of the third spring 20, the piston plate 18 and the contact rod 19 slide downward and reset accordingly, so that the dust and impurities staying near the cleaning wheel 16 and the cleaning brush 17 can be blown away, ensuring the use effect of the cleaning wheel 16 and the cleaning brush 17.

[0041] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A screen window slideway and a screen window with a positioning structure, comprising a window frame (1), a screen window (2) being slidably connected to the window frame (1), wherein: The invention also comprises two transversely symmetrical mounting blocks (3), the two transversely symmetrical mounting blocks (3) are fixedly connected to the transverse sides of the top of the screen window (2), the mounting blocks (3) are fixedly connected to a fixing rod (301), the fixing rod (301) is rotatably connected to a rotating top block (4), the rotating top block (4) is arranged in an inclined manner as a whole, the bottom end of the rotating top block (4) contacts the inner wall of the window frame (1), two transversely symmetrical sliding rods (5) are slidably connected to the screen window (2), the outer ends of the sliding rods (5) are movably connected to adjacent rotating top blocks (4), the sliding rods (5) are fixedly connected to a connecting piece (501), a first spring (6) is connected between the connecting piece (501) and the screen window (2), the first spring (6) is sleeved on the sliding rod (5), the window frame (1) and the screen window (2) are provided with an anti-falling component, the anti-falling component is used to prevent the screen window (2) from falling suddenly, and the screen window (2) is provided with a locking component for preventing children and pets from opening by mistake.

2. A screen window slideway and screen window with a positioning structure according to claim 1, characterized in that: The anti-falling component comprises two transversely symmetrical locking rods (7), the two transversely symmetrical locking rods (7) are fixedly connected to the transverse sides of the screen window (2), the middle parts of the transverse sides of the screen window (2) are each provided with an oblique groove (701), the locking rods (7) are located in the oblique groove (701), two transversely symmetrical sliding blocks (8) are slidably connected to the window frame (1), a second spring (9) is connected between the sliding block (8) and the window frame (1), and an interception plate (10) is fixedly connected to the sliding block (8).

3. A screen window slideway and screen window with a positioning structure according to claim 2, characterized in that: A side of the interception plate (10) close to the locking rod (7) is provided with equidistantly distributed protrusions for intercepting and clamping the locking rod (7).

4. A screen window slideway and screen window with a positioning structure according to claim 3, characterized in that: The locking assembly comprises two transversely symmetrical guide plates (11), the two transversely symmetrical guide plates (11) are fixedly connected to the screen window (2), a sliding plate (12) is slidably connected between the two guide plates (11), an adjusting rod (13) is rotatably connected to the screen window (2), the adjusting rod (13) and the sliding plate (12) are connected via threads, two transversely symmetrical rubber limit blocks (14) are slidably connected to the top of the screen window (2), a contact block (141) is fixedly connected to the rubber limit block (14), and a spring piece (142) is connected between the rubber limit block (14) and the screen window (2).

5. A screen window slideway and screen window with a positioning structure according to claim 4, characterized in that: Both lateral ends of the sliding plate (12) are provided with upwardly bent protrusions, and the side of the contact block (141) close to the sliding plate (12) is inclined, and the sliding plate (12) and the contact block (141) are pressed and matched.

6. A screen window slideway and screen window with a positioning structure according to claim 5, characterized in that: It also includes a cleaning component for cleaning impurities in the slideway of the window frame (1), the cleaning component including two vertically symmetrical fixed shafts (15), the two vertically symmetrical fixed shafts (15) are fixedly connected to the mounting block (3), a cleaning wheel (16) is rotatably connected to the fixed shaft (15), and cleaning brushes (17) are fixedly connected to both sides of the top and bottom ends of the mounting block (3), and the cleaning brushes (17) are in contact with adjacent cleaning wheels (16).

7. A screen window slideway and screen window with a positioning structure according to claim 6, characterized in that: The cleaning assembly also includes a cleaning component for cleaning the cleaning wheel (16) and the cleaning brush (17). The cleaning component includes two transversely symmetrical piston plates (18). The two transversely symmetrical piston plates (18) are slidably connected to the screen window (2). An air cavity (21) is provided on both transverse sides of the screen window (2). The air cavity (21) has a large lower space and a narrow upper space. The air cavity (21) is communicated with the mounting block (3). The piston plate (18) is located in the lower space of the air cavity (21). The bottom end of the piston plate (18) is fixedly connected to a contact rod (19). The bottom end of the contact rod (19) extends out of the screen window (2). A third spring (20) is connected between the piston plate (18) and the screen window (2). The third spring (20) is sleeved on the contact rod (19).