Filter with adjustable center frequency and constant and adjustable absolute bandwidth

Abstract

The invention relates to the technical field of filter mounting, in particular to a filter with adjustable center frequency and constant and adjustable absolute bandwidth, which comprises a filter shell, a clamping mechanism and a limiting mechanism, a cover plate is fixedly mounted on the rear side of the filter shell, a fixing strip is arranged on the rear side of the cover plate, and a plurality of mounting holes are formed in the fixing strip. The cover plate is stably installed on the fixing strip in the transverse direction and the longitudinal direction through the clamping mechanism and the limiting mechanism, installation of the filter shell and the cover plate can be achieved whether the fixing strip is vertically installed or horizontally installed, the situation that an operator uses complex fixing tools and fixing steps is avoided, and the stability and reliability of equipment are improved. No matter whether the fixing strip is vertically installed or horizontally installed, the installation mode can meet different installation requirements, and the flexibility of equipment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of filter installation, and particularly to a filter with adjustable center frequency and continuously adjustable absolute bandwidth. Background Art

[0002] A filter with adjustable center frequency and continuously adjustable absolute bandwidth is a high-performance filter that can maintain a constant bandwidth while adjusting the center frequency. It mainly relies on technologies such as varactor diodes, mechanical tuning, microelectromechanical systems, and digital tuning. By changing the applied voltage, its capacitance value is adjusted, thereby affecting the resonant frequency of the filter. By rotating or sliding the resonant element, the resonant frequency is changed. By utilizing the change of the micro-mechanical structure, high-precision and high-reliability frequency tuning is achieved. In digital signal processing or software radio systems, the frequency response is adjusted by changing the filter coefficients.

[0003] When using a filter to filter signals in a circuit, it needs to be installed inside an electrical device. Generally, the fixing holes of the filter need to be aligned with the screw holes on the bottom plate, and screws are used to fix the filter on the bottom plate. During this process, the operator needs to prepare all the supporting screws and tools, and then fix the four corners of the filter one by one. When using screws to fix the filter, if the screws are tightened too tightly, mechanical stress may be imposed on the filter. This stress may cause damage to the internal components of the filter or a decline in performance. Especially for some sensitive components, this impact may be more significant. In addition, this installation method may not be suitable for devices that require frequent filter replacement. Because each replacement requires removing the screws, the operation is rather cumbersome, increasing the maintenance cost and time. Summary of the Invention

[0004] The purpose of the present invention is to provide an auxiliary structure for the construction of steel structures in building engineering to solve the problems raised in the above background art.

[0005] The technical solution adopted by the present application to solve its technical problems is: A filter with adjustable center frequency and continuously adjustable absolute bandwidth, comprising: a filter housing, a cover plate is fixedly installed on the rear side of the filter housing, a fixing strip is arranged on the rear side of the cover plate, and a plurality of mounting holes are opened on the fixing strip. It is characterized in that it further comprises:

[0006] A clamping mechanism, the clamping mechanism is arranged on the cover plate, the clamping mechanism includes a pressing component and a fixing component, the pressing component includes movable columns symmetrically arranged inside the cover plate, the fixing component includes synchronizing blocks fixedly arranged at the ends of the movable columns, and clamping claws are arranged on the synchronizing blocks. The clamping mechanism is used to install the filter housing and the cover plate onto the fixing strip;

[0007] The limiting mechanism is arranged on the cover plate. The limiting mechanism includes a fixed block fixedly arranged in the middle of the cover plate. Two abutting blocks are symmetrically arranged on both sides of the fixed block. The limiting mechanism is used to fix the position of the cover plate.

[0008] Preferably, an input end is fixedly arranged on one side of the filter housing, an output end is arranged on the other side of the filter housing, and a resonant element and a variable element are arranged in the inner cavity of the filter housing.

[0009] Preferably, the pressing assembly further includes cylindrical grooves one symmetrically opened on the cover plate. A pressing column is slidably connected to the inner wall of the cylindrical groove one. A group of fixing pieces one are symmetrically fixedly arranged at the end of the pressing column. Through holes are respectively and penetratingly opened on the fixing pieces one. A connecting shaft is fixedly arranged through the through holes.

[0010] Preferably, a movable cavity one is further opened on the cover plate. The movable cavity one is communicated with the cylindrical groove one. The end of the pressing column, the fixing piece one and the connecting shaft are all located in the movable cavity one. A cylindrical groove two communicated with the movable cavity one is arranged on one side of the movable cavity one. The inner wall of the cylindrical groove two is slidably connected with the movable column.

[0011] Preferably, a movable cavity two is arranged in the middle of the cylindrical groove two. Limiting rings are arranged in the movable cavities. The limiting rings are fixedly arranged on the outer surface of the movable column. A first spring is sleeved on the outer surface of the movable column. The first spring is located in the movable cavity two.

[0012] Preferably, a fixing piece two is fixedly arranged at the top of the movable column. The fixing piece two is located between the fixing pieces one. A straight slot is penetratingly opened on the fixing piece two. The straight slot is inclined. The inner wall of the straight slot is slidably connected with the connecting shaft, and the connecting shaft penetrates through the straight slot.

[0013] Preferably, the fixing assembly further includes grooves symmetrically opened at the rear side of the cover plate. The inner wall of the groove is slidably connected with the synchronous block.

[0014] Preferably, the limiting mechanism further includes square grooves symmetrically opened on the fixed block. Movable blocks one are slidably arranged on the inner walls of the square grooves. The ends of the movable blocks one are fixedly connected with the abutting blocks.

[0015] Preferably, circular grooves communicated with the square grooves are respectively opened at the bottoms of the square grooves. Chute grooves are symmetrically opened on the groove walls of the circular grooves. Movable blocks two are slidably arranged on the inner walls of the circular grooves. One side of the movable blocks two is fixedly connected with the movable blocks one.

[0016] Preferably, sliding blocks are symmetrically arranged on the outer surface of the movable blocks two. The outer surfaces of the sliding blocks slide in the chute grooves. A second spring is sleeved on the outer surface of the movable blocks. The second spring is located in the inner cavity of the square groove.

[0017] The beneficial effects of this application are as follows:

[0018] A filter with adjustable center frequency and continuously adjustable absolute bandwidth provided by this application realizes the quick installation and disassembly of the filter housing and the cover plate from the fixing strip through the combined use of a pressing component and a fixing component. The pressing component is responsible for responding to the external pressing of the operator and driving the fixing component to clamp the fixing strip, thereby ensuring the stable installation of the filter. The fixing component includes a synchronization block and a claw, which are used to clamp the fixing strip under the action of pressing to prevent the filter from loosening. This not only simplifies the installation and disassembly process of the filter but also improves the up-and-down stability of the device and prevents the cover plate from shaking up and down.

[0019] A filter with adjustable center frequency and continuously adjustable absolute bandwidth provided by this application has a stopper of the limiting mechanism stuck in the installation hole of the fixing strip, which laterally fixes the cover plate and prevents the cover plate from shaking left and right. By stably installing the cover plate on the fixing strip both horizontally and vertically, the installation of the filter housing and the cover plate can be achieved regardless of whether the fixing strip is installed vertically or horizontally. This avoids the operator using complex fixing tools and fixing steps, and improves the stability and reliability of the device. Whether the fixing strip is installed vertically or horizontally, this installation method can adapt to different installation requirements and improves the flexibility of the device.

[0020] In addition to the purposes, features, and advantages described above, this application has other purposes, features, and advantages. The following will refer to the drawings to further elaborate on this application in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the cover plate structure after removing the fixing strip of the present invention;

[0023] Figure 3 It is a schematic diagram of the cross-section structure of the cover plate of the present invention;

[0024] Figure 4 It is the present invention Figure 3 The enlarged schematic diagram of the structure at A in;

[0025] Figure 5 It is a partial mechanism structure schematic diagram of the pressing component of the clamping mechanism of the present invention;

[0026] Figure 6 It is a partial mechanism structure schematic diagram of the inner cavity of the cover plate of the present invention;

[0027] Figure 7 It is a schematic diagram of the overall structure of the present invention from another perspective;

[0028] Figure 8 For the present invention Figure 7 Schematic enlarged structure diagram at position B in the present invention;

[0029] Figure 9 Schematic structure diagram of the limit mechanism of the present invention;

[0030] Figure 10 For the present invention Figure 9 Schematic enlarged structure diagram at position C in the present invention.

[0031] Description of figure numbers:

[0032] 1. Filter housing; 2. Cover plate; 3. Input end; 4. Output end; 5. Fixed strip; 6. Mounting hole; 7. Clamping mechanism; 8. Pressing component; 9. First cylindrical groove; 10. Pressing column; 11. First fixing piece; 12. Through hole; 13. Connecting shaft; 14. First movable cavity; 15. Second cylindrical groove; 16. Movable column; 17. Limiting ring; 18. Second fixing piece; 19. Straight notch; 20. Second movable cavity; 21. First spring; 22. Fixing component; 23. Groove; 24. Synchronous block; 25. Claw; 26. Limit mechanism; 27. Fixed block; 28. Square groove; 29. First movable block; 30. Circular groove; 31. Sliding groove; 32. Second movable block; 33. Slider; 34. Second spring; 35. Block. Detailed implementation manners

[0033] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will describe the present application in detail with reference to the drawings and in combination with the embodiments.

[0034] In order to enable those skilled in the art to better understand the solution of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0035] Please refer to Figures 1 to 10, A filter with adjustable center frequency and continuously adjustable absolute bandwidth, comprising: a filter housing 1 which provides physical protection for the sensitive electronic components inside the filter, preventing damage to the components caused by external impacts, vibrations or environmental factors. A cover plate 2 is fixedly installed at the rear side of the filter housing 1. The cover plate 2 covers the opening end of the filter to ensure the isolation of the internal circuit from the external environment, preventing dust, moisture or other impurities from entering the filter interior. The cover plate 2 is usually fixed to the housing by screws or snaps, providing additional support for the internal components and enhancing the overall structural strength of the filter. A fixing strip 5 is provided at the rear side of the cover plate 2, and a plurality of mounting holes 6 are formed in the fixing strip 5. The fixing strip 5 is installed on the inner wall of the electrical equipment through the mounting holes 6.

[0036] Please refer to Figures 1 to 10 , A filter with adjustable center frequency and continuously adjustable absolute bandwidth, further comprising: a clamping mechanism 7 which is arranged on the cover plate 2. The clamping mechanism 7 includes a pressing component 8 and a fixing component 22. The pressing component 8 includes movable columns 16 symmetrically arranged inside the cover plate 2. The fixing component 22 includes a synchronous block 24 fixedly arranged at the end of the movable column 16, and claws 25 are arranged on the synchronous block 24. The clamping mechanism 7 is used to install the filter housing 1 and the cover plate 2 onto the fixing strip 5. Through the cooperation of the pressing component 8 and the fixing component 22, the clamping mechanism 7 realizes the quick installation and disassembly of the filter housing 1 and the cover plate 2 from the fixing strip 5. The pressing component 8 is responsible for responding to the external pressing of the operator and driving the fixing component 22 to clamp the fixing strip 5, thereby ensuring the stable installation of the filter. The fixing component 22 includes the synchronous block 24 and the claws 25, which are used to clamp the fixing strip 5 under the pressing action to prevent the filter from loosening. This not only simplifies the installation and disassembly process of the filter, but also improves the up-and-down stability of the device, avoiding the up-and-down shaking of the cover plate 2.

[0037] Please refer to Figures 1 to 10 , A filter with adjustable center frequency and continuously adjustable absolute bandwidth, further comprising: a limiting mechanism 26 which is arranged on the cover plate 2. The limiting mechanism 26 includes a fixing block 27 fixedly arranged in the middle of the cover plate 2, and resisting blocks 35 are symmetrically arranged on both sides of the fixing block 27. The limiting mechanism 26 is used to fix the position of the cover plate 2. The resisting blocks 35 are symmetrically arranged on both sides of the fixing block 27 and cooperate with the mounting holes 6 of the fixing strip 5 to ensure the stable connection of the cover plate 2. The design of the resisting blocks 35 improves the lateral stability and reliability of the device, avoiding the left-and-right shaking of the cover plate 2.

[0038] Among them, it should be emphasized that an input end 3 is fixedly arranged on one side of the filter housing 1, an output end 4 is arranged on the other side of the filter housing 1, and a resonant element and a variable element are arranged in the inner cavity of the filter housing 1. The input end 3 is used to receive the signal to be processed, and the output end 4 is used to send the processed signal. They play the role of a signal transmission bridge in the filter, ensuring that the signal can smoothly enter and leave the filter. The resonant elements, such as inductors and capacitors, together constitute a resonant circuit and determine the center frequency of the filter. Through their impedance characteristics, they allow signals of specific frequencies to pass through, while blocking or weakening signals of other frequencies, thereby achieving the filtering function. The variable elements, such as varactor diodes and adjustable inductors, are used to adjust the inductance value or capacitance value of the filter, thereby realizing the dynamic control of the filter characteristics. This design enables the filter to adjust its operating frequency or bandwidth as needed, improving the flexibility and practicality of the device.

[0039] Furthermore, specifically refer to Figures 2 to 7 The pressing assembly 8 further includes cylindrical grooves 9 symmetrically formed on the cover plate 2. A pressing column 10 is slidably connected to the inner wall of the cylindrical groove 9. A group of fixing pieces 11 are symmetrically fixedly arranged at the end of the pressing column 10. Through holes 12 are respectively formed through the fixing pieces 11, and a connecting shaft 13 is fixedly arranged through the through holes 12. An active cavity 14 is also formed on the cover plate 2. The active cavity 14 communicates with the cylindrical groove 9. The end of the pressing column 10, the fixing pieces 11, and the connecting shaft 13 are all located in the active cavity 14. A cylindrical groove 15 communicating with the active cavity 14 is arranged on one side of the active cavity 14. The inner wall of the cylindrical groove 15 is slidably connected to the active column 16. An active cavity 20 is arranged in the middle of the cylindrical groove 15. A limiting ring 17 is arranged in the active cavity. The limiting ring 17 is fixedly arranged on the outer surface of the active column 16. A first spring 21 is sleeved on the outer surface of the active column 16. The first spring 21 is located in the active cavity 20.

[0040] Among them, a fixing piece 18 is fixedly arranged at the top of the active column 16. The fixing piece 18 is located between the fixing pieces 11. A straight slot 19 is formed through the fixing piece 18. The straight slot 19 is inclined. The inner wall of the straight slot 19 is slidably connected to the connecting shaft 13, and the connecting shaft 13 penetrates through the straight slot 19. It should be noted that the fixing assembly 22 further includes grooves 23 symmetrically formed on the rear side of the cover plate 2. The inner wall of the groove 23 is slidably connected to the synchronous block 24.

[0041] By the operator simultaneously pinching the pressing column 10, it is urged that the connecting shaft 13 on the first movable piece slides in the straight groove 19 of the second connecting piece, and the straight groove 19 is inclined, so that the connecting shaft 13 jacks up the movable column 16. Under the limiting effect of the limiting ring 17, the first spring 21 is squeezed and compressed. At this time, the fixed block 27 of the fixing assembly 22 is driven by the movable column 16, prompting the two claws 25 to move away from each other. At this time, there is enough distance between the claws 25 to be inserted into the fixing strip 5. When the inclined surfaces of the claws 25 and the fixing strip 5 are staggered, the pressing column 10 is released. At this time, when the restriction of the first spring 21 is released, while the movable column 16 is reset, it drives the claws 25 to be stuck on the fixing strip 5. The whole operation process is simple and clear, and only by pinching the pressing column 10 can the installation and fixation of the filter be completed. Through the coordinated work of components such as the connecting shaft 13, the movable column 16 and the spring, it is ensured that the claws 25 can be firmly stuck on the fixing strip 5, improving the longitudinal stability of the device.

[0042] Furthermore, specifically refer to Figures 8 to 10

[0043] When the operator installs the fixed block 27 by aligning it with the mounting hole 6 of the fixing strip 5, the fixed block 27 will gradually approach the mounting hole 6 and continue to align until the abutting block 35 fits the mounting hole 6. At this time, the opening of the mounting hole 6 will squeeze the inclined surface of the abutting block 35, prompting the abutting block 35 to squeeze the first movable block 29 to slide in the square groove 28. At the same time, the second movable block 32 slides synchronously in the circular groove 30 through the slider 33 until the distance between the two abutting blocks 35 is equal to the distance between the mounting holes 6. At this time, the cover plate 2 is horizontally fixed, avoiding the left - right shaking of the cover plate 2. By horizontally and longitudinally stably installing the cover plate 2 on the fixing strip 5, whether the fixing strip 5 is installed vertically or horizontally, the installation of the filter housing 1 and the cover plate 2 can be realized, avoiding the operator using complex fixing tools and fixing steps, and improving the stability and reliability of the device. Whether the fixing strip 5 is installed vertically or horizontally, this installation method can adapt to different installation requirements and improve the flexibility of the device.

[0044] Through all the above - mentioned embodiments, the working principle of the present invention is:

[0045] The operator simultaneously pinches the pressing column 10, causing the connecting shaft 13 on the first movable piece to slide within the straight slot 19 of the second connecting piece. The straight slot 19 is inclined, such that the connecting shaft 13 jacks up the movable column 16. Under the restricting action of the limiting ring 17, the first spring 21 is squeezed and compressed. At this time, the fixed block 27 of the fixing assembly 22 is driven by the movable column 16, causing the two claw fingers 25 to move away from each other. At this time, there is sufficient distance between the claw fingers 25 to be inserted into the fixing strip 5. When the claw fingers 25 cross the inclined surface of the fixing strip 5, release the pressing column 10. At this time, when the restriction of the first spring 21 is released, while the movable column 16 is reset, it drives the claw fingers 25 to latch onto the fixing strip 5. The entire operation process is simple and clear, and only by pinching the pressing column 10 can the installation and fixation of the filter be completed. Through the coordinated work of components such as the connecting shaft 13, movable column 16, and spring, it is ensured that the claw fingers 25 can be firmly latched onto the fixing strip 5, improving the longitudinal stability of the device;

[0046] While the operator pinches the pressing column 10, align the fixed block 27 with the mounting hole 6 of the fixing strip 5 for installation. The fixed block 27 will gradually approach the mounting hole 6 and continue to be aligned until the abutting block 35 fits against the mounting hole 6. At this time, the opening of the mounting hole 6 will squeeze the inclined surface of the abutting block 35, causing the abutting block 35 to squeeze the first movable block 29 to slide within the square slot 28. At the same time, the second movable block 32 synchronously slides within the circular slot 30 through the slider 33 until the distance between the two abutting blocks 35 is equal to the distance between the mounting holes 6. At this time, the cover plate 2 is horizontally fixed, preventing the cover plate 2 from shaking left and right. By horizontally and longitudinally stably installing the cover plate 2 on the fixing strip 5, whether the fixing strip 5 is vertically installed or horizontally installed, the installation of the filter housing 1 and the cover plate 2 can be achieved, avoiding the operator from using complex fixing tools and fixing steps, and improving the stability and reliability of the device. Whether the fixing strip 5 is vertically installed or horizontally installed, this installation method can adapt to different installation requirements and improve the flexibility of the device.

[0047] Those of ordinary skill in the art should understand that the discussion of any above embodiments is only exemplary. Under the concept of the present invention, the technical features between the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. There are many other variations in different aspects of the present invention as described above, and they are not provided in detail for the sake of brevity.

[0048] The present invention aims to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A filter with adjustable center frequency and adjustable absolute bandwidth, comprising: Filter housing (1), a cover plate (2) is fixedly installed on the rear side of the filter housing (1), a fixing strip (5) is arranged on the rear side of the cover plate (2), and a plurality of mounting holes (6) are formed in the fixing strip (5). It is characterized in that it further comprises: A clamping mechanism (7), the clamping mechanism (7) is arranged on the cover plate (2), the clamping mechanism (7) comprises a pressing component (8) and a fixing component (22), the pressing component (8) comprises movable columns (16) symmetrically arranged in the cover plate (2), the fixing component (22) comprises synchronous blocks (24) fixedly arranged at the ends of the movable columns (16), clamping claws (25) are arranged on the synchronous blocks (24), and the clamping mechanism (7) is used for installing the filter housing (1) and the cover plate (2) onto the fixing strip (5); A limiting mechanism (26), the limiting mechanism (26) is arranged on the cover plate (2), the limiting mechanism (26) comprises a fixing block (27) fixedly arranged in the middle of the cover plate (2), and abutting blocks (35) are symmetrically arranged on both sides of the fixing block (27), and the limiting mechanism (26) is used for fixing the position of the cover plate (2).

2. The adjustable center frequency and adjustable absolute bandwidth filter according to claim 1, characterized in that An input end (3) is fixedly arranged on one side of the filter housing (1), an output end (4) is arranged on the other side of the filter housing (1), and a resonant element and a variable element are arranged in the inner cavity of the filter housing (1).

3. A filter with adjustable center frequency and continuously adjustable absolute bandwidth according to claim 1, characterized in that, The pressing component (8) further comprises cylindrical grooves one (9) symmetrically formed in the cover plate (2), a pressing column (10) is slidably connected to the inner wall of the cylindrical groove one (9), a group of fixing pieces one (11) are symmetrically and fixedly arranged at the end of the pressing column (10), through holes (12) are formed through the fixing pieces one (11), and a connecting shaft (13) is fixedly arranged through the through holes (12).

4. A filter with adjustable center frequency and adjustable absolute bandwidth as claimed in claim 3, characterized in that, An activity cavity one (14) is further formed in the cover plate (2), the activity cavity one (14) communicates with the cylindrical groove one (9), the end of the pressing column (10), the fixing piece one (11) and the connecting shaft (13) are all located in the activity cavity one (14), a cylindrical groove two (15) communicated with the activity cavity one (14) is arranged on one side of the activity cavity one (14), and the inner wall of the cylindrical groove two (15) is slidably connected to the movable column (16).

5. A filter with adjustable center frequency and continuously adjustable absolute bandwidth according to claim 4, characterized in that, An activity cavity two (20) is arranged in the middle of the cylindrical groove two (15), limiting rings (17) are arranged in the activity cavities, the limiting rings (17) are fixedly arranged on the outer surface of the movable column (16), and a first spring (21) is sleeved on the outer surface of the movable column (16), and the first spring (21) is located in the activity cavity two (20).

6. A filter with adjustable center frequency and continuously adjustable absolute bandwidth according to claim 5, characterized in that, A fixing piece two (18) is fixedly arranged at the top of the movable column (16), the fixing piece two (18) is located between the fixing pieces one (11), a straight slot (19) is formed through the fixing piece two (18), the straight slot (19) is inclined, the inner wall of the straight slot (19) is slidably connected to the connecting shaft (13), and the straight slot (19) is penetrated by the connecting shaft (13).

7. A filter with adjustable center frequency and adjustable absolute bandwidth as claimed in claim 1, characterized in that, The fixed component (22) further includes grooves (23) symmetrically formed at the rear side of the cover plate (2), and the inner wall of the groove (23) is slidably connected to the synchronization block (24).

8. A filter with adjustable center frequency and continuously adjustable absolute bandwidth according to claim 1, characterized in that, The limiting mechanism (26) further includes square grooves (28) symmetrically formed in the fixed block (27), and a first movable block (29) is slidably arranged on the inner wall of the square groove (28), and the ends of the first movable block (29) are fixedly connected to the abutting blocks (35).

9. The tunable center frequency and continuously tunable absolute bandwidth filter according to claim 8, wherein, Circular grooves (30) communicating with the square grooves (28) are formed at the bottom of the square grooves (28), and sliding grooves (31) are symmetrically formed on the inner wall of the circular groove (30). A second movable block (32) is slidably arranged on the inner wall of the circular groove (30), and one side of the second movable block (32) is fixedly connected to the first movable block (29).

10. A filter with adjustable center frequency and adjustable absolute bandwidth as claimed in claim 9, characterized in that, Sliders (33) are symmetrically arranged on the outer surface of the second movable block (32), and the outer surface of the slider (33) slides in the sliding groove (31). A second spring (34) is sleeved on the outer surface of the movable block, and the second spring (34) is located in the inner cavity of the square groove (28).

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