Switching device for multi-split air conditioner

Abstract

The utility model relates to the technical field of air conditioner technologies, in particular to a switching device for a multi-split air conditioner, which has the function of automatically cleaning accumulated snow, avoids adverse effects caused by the accumulated snow and is better in reliability. Comprising a base and a shell; the top plate is located above the shell, the two sides of the lower end face of the top plate are each provided with the two elastic wheel frames in a front-back mode, the rollers are rotationally installed at the lower ends of the multiple elastic wheel frames, and the track frames are installed on the left side and the right side of the upper end face of the shell; the four rolling wheels are in rolling connection with the two rail frames respectively, the two hooks are installed on the rear side of the shell, two square holes are formed in the rear side of the top plate, hook parts of the two hooks stretch into the two square holes of the top plate from top to bottom respectively to hook the top plate, and the electric winding machine is installed on the rear portion of the upper end face of the shell. One end of the inhaul cable is wound on a reel device of the electric winding machine, and the other end of the inhaul cable is connected with the rear portion of the top plate.

Description

Technical Field

[0001] The utility model relates to the technical field of air conditioner technology, in particular to a switching device for a multi-connected air conditioner. Background Art

[0002] The multi-connected air conditioner system is mainly used to control the indoor temperature and humidity. Generally, it includes one or more outdoor units, one or more indoor units and a wired controller. The wired controller is connected to the indoor unit, and the indoor unit is then connected to the outdoor unit. The outdoor unit generally consists of an outdoor heat exchanger, a compressor and other refrigeration accessories; the indoor unit consists of a fan and a heat exchanger, etc. Compared with multiple household air conditioners, the outdoor units of the multi-connected air conditioner system are shared, which can effectively reduce the equipment cost. Through the switching device, centralized management of each indoor unit can be realized. One indoor unit can be started independently, or multiple indoor units can be started simultaneously, making the control more flexible.

[0003] In the prior art, the Chinese utility model patent with the application number CN201620925793.2, a switching device for a multi-connected air conditioner and a multi-connected air conditioner having the same, proposed a switching device for a multi-connected air conditioner. By separating the bottom surface of the water receiving tray from the inner wall of the base and setting a shock-absorbing pad on the water receiving tray, the water receiving tray is separated from the fixing member. Thus, it effectively avoids the noise generated when the refrigerant flows through the heat exchange system from being transmitted to the base through the water receiving tray, thereby greatly reducing the noise of the air conditioner using the base assembly, and does not affect the use occasion and installation position of the switching device, expanding the use occasion and installation position of the air conditioner, and improving the comfort of the air conditioner.

[0004] Since the switching device of the multi-connected air conditioner is generally arranged outdoors or on the roof following the outdoor unit, it is often covered by snow in the winter in the north. The thick snow exerts pressure on the shell of the switching device of the multi-connected air conditioner, resulting in the deformation of the shell. The snow will melt and freeze repeatedly in winter. When melting, it not only takes away the heat of the switching device of the multi-connected air conditioner, but also the snow water is easy to penetrate into the inside of the switching device of the multi-connected air conditioner, causing adverse effects on the circuit and pipeline. Summary of the Utility Model

[0005] To solve the above technical problems, the utility model provides a switching device for a multi-connected air conditioner, which has the function of automatically clearing snow, avoids the adverse effects caused by snow, and has better reliability.

[0006] A switching device for a multi-connected air conditioner of the present utility model includes a base and a housing. An electromagnetic valve group and a distribution pipeline are arranged on the base, and the housing is installed on the base. It further includes a top plate, an elastic wheel frame, a roller, a track frame, a hook, an electric winch, and a cable. The top plate is located above the housing. Two elastic wheel frames are arranged front and back on both sides of the lower end surface of the top plate. Springs are arranged in the middle of multiple elastic wheel frames. Rollers are rotatably installed at the lower ends of multiple elastic wheel frames. Track frames are installed on the left and right sides of the upper end surface of the housing. Tracks inclined towards the front of the housing are arranged on the two track frames. The four rollers are respectively in rolling connection with the tracks of the two track frames. Two hooks are installed at the rear side of the housing. Two square holes are arranged at the rear side of the top plate. The hook parts of the two hooks respectively extend downward from top to bottom into the two square holes of the top plate to hook the top plate. The electric winch is installed at the rear part of the upper end surface of the housing. One end of the cable is wound on the reel of the electric winch, and the other end of the cable is connected to the rear part of the top plate. In the normal state, the hook parts of the two hooks extend into the two square holes of the top plate to hook and lock the top plate, so that the top plate is kept above the housing. When it snows, the top plate replaces the upper end surface of the housing to bear the snow accumulation. As the thickness of the snow accumulation increases, its weight increases synchronously, causing the top plate to gradually compress the springs in multiple elastic wheel frames, causing multiple elastic wheel frames to contract and the height of the top plate to decrease. When the top plate drops to disengage from the two hooks, under the action of the component force of the gravity of the top plate and the snow accumulation along the inclined tracks of the track frames, the multiple rollers move along the inclined tracks of the two track frames towards the front of the housing, thereby driving the top plate to move forward of the housing. The front side of the top plate moves out of the two track frames and then turns downward, so that the snow accumulation on the top plate is poured out. After the snow accumulation is cleared, the electric winch operates to wind the cable, and the cable pulls the top plate back onto the housing and makes the four rollers return to the initial positions on the two track frames. The hook parts of the two hooks extend into the two square holes of the top plate again to hook and lock the top plate; realizing the function of automatically clearing snow accumulation, avoiding the oppression and deformation of the housing of the switching device of the multi-connected air conditioner caused by thick snow accumulation, and at the same time reducing the adverse effects on the circuits and pipelines inside the switching device of the multi-connected air conditioner during the melting of the snow accumulation, with better reliability.

[0007] Preferably, it further includes two supports, two columns, and two shock-absorbing springs. The two supports are respectively installed at both ends of the rear side wall of the housing. The two columns are respectively vertically installed on the two supports. The middle parts of the two hooks are respectively hinged at the tops of the two columns. The lower ends of the two shock-absorbing springs are respectively rotatably connected to the two supports, and the upper ends of the two shock-absorbing springs are respectively rotatably connected to the rear ends of the two hooks. The two supports and the two columns provide rotational support for the two hooks. The elastic forces of the two shock-absorbing springs keep the two hooks elastically stable, so that when the top plate is reset, the hook parts of the two hooks can be pushed up and extend into the two square holes of the top plate, improving the convenience of resetting the top plate.

[0008] Preferably, it further includes two limiting bars and two limiting blocks. The two limiting bars are respectively installed on the inclined tracks of the two track frames. The two limiting bars limit and guide the multiple rollers. The two limiting blocks are respectively installed at the front parts of the two track frames. The two limiting blocks limit the forward movement distance of the two rollers located at the rear part of the top plate, and the two limiting blocks also limit the backward movement distance of the two rollers located at the front part of the top plate. Due to the limiting and guiding effect of the two limiting bars, the four rollers are not easily separated from the inclined tracks of the two track frames. The two rollers located at the rear part of the top plate are blocked by the two limiting blocks, so that the two rollers are retained on the two track frames. When the top plate is reset, the two rollers located at the front part of the top plate are blocked by the two limiting blocks, thereby positioning the top plate and making the reset of the top plate more accurate.

[0009] Preferably, it further includes a first contact switch and a second contact switch. The first contact switch is installed at the front part of the track frame, and the second contact switch is installed at the rear part of the track frame. The contact arms of the first contact switch and the second contact switch both extend into the track of the track frame. The first contact switch and the second contact switch are both electrically connected to the controller of the electric winch. When the top plate moves forward to remove the snow on it, when the two rollers located at the rear part of the top plate are blocked by the two limiting blocks, the rollers contact the contact arm of the first contact switch, and the first contact switch sends a signal to the controller of the electric winch, causing the electric winch to operate and reel in the cable, so that the top plate starts to reset. When the top plate is reset in place, the rollers contact the contact arm of the second contact switch, and the second contact switch sends a signal to the controller of the electric winch, causing the electric winch to stop, realizing the automatic control of the electric winch.

[0010] Preferably, it further includes two front brackets and a scraper. The two front brackets are respectively installed on both sides of the front part of the housing. The two ends of the scraper are respectively connected to the two front brackets. When the top plate moves out of the housing for flipping, the scraper scrapes the upper end surface of the top plate, thereby improving the effect of snow removal on the top plate.

[0011] Preferably, it further includes two screws and two nuts. Screws are provided at both ends of the scraper. The two screws are respectively inserted into the two front brackets movably. The two nuts are respectively screwed on the two screws and locked with the two front brackets. Rotate the scraper to adjust the distance between the edge of the scraper and the housing, thereby adjusting the gap between the edge of the scraper and the upper end surface of the top plate. Tighten the two nuts to lock the two screws and the two front brackets, and lock the scraper to achieve different snow scraping effects.

[0012] Compared with the prior art, the beneficial effects of the utility model are as follows: in a normal state, the hooks of the two hooks extend into the two square holes of the top plate to hook and lock the top plate, so that the top plate is kept above the shell; when it snows, the top plate replaces the upper end surface of the shell to bear the accumulated snow; as the thickness of the accumulated snow increases, its weight increases synchronously, so that the top plate gradually compresses the springs in the multiple elastic wheel frames, so that the multiple elastic wheel frames shrink and the height of the top plate is reduced; when the top plate is lowered to be disengaged from the two hooks, under the component force of the gravity of the top plate and the accumulated snow along the inclined tracks of the track frames, the multiple rollers move toward the front of the shell along the inclined tracks of the two track frames, thereby bringing The top plate is moved to the front of the shell, and the front side of the top plate moves out of the two track frames and then flips downward, so that the snow on the top plate dumps down. After the snow is cleared, the electric winder runs the winder cable, and the cable pulls the top plate back to the shell, and returns the four rollers to their initial positions on the two track frames. The hooks of the two hooks are again extended into the two square holes of the top plate to hook and lock the top plate; the function of automatic snow cleaning is realized, avoiding the compression and deformation of the shell of the switching device of the multi-split air conditioner caused by thick snow, and at the same time reducing the adverse effects of melting snow on the circuits and pipes inside the switching device of the multi-split air conditioner, and the reliability is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the utility model;

[0014] Figure 2 It is a side view structural schematic diagram of the utility model;

[0015] Figure 3 It is a rear axonometric structural schematic diagram of the utility model;

[0016] Figure 4 It is a schematic diagram of the structure of the utility model in a decomposed state;

[0017] Figure 5 It is a schematic diagram of the structure of the utility model when the top plate is removed;

[0018] Figure 6 It is a schematic diagram of the structure of the track frame and the hook;

[0019] Figure 7 It is a schematic diagram of the structure when looking up at the top plate and other structures.

[0020] Markings in the attached drawings: 1. base; 2. shell; 3. top plate; 4. elastic wheel frame; 5. roller; 6. track frame; 7. hook; 8. electric winder; 9. cable; 10. support; 11. column; 12. shock-absorbing spring; 13. limit strip; 14. limit block; 15. contact switch 1; 16. contact switch 2; 17. front bracket; 18. scraper; 19. screw; 20. nut. DETAILED DESCRIPTION

[0021] To facilitate the understanding of the present utility model, the present utility model will be described more comprehensively below with reference to the relevant drawings. The present utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present utility model more thorough and comprehensive.

[0022] Embodiment 1

[0023] As Figure 1 、 Figure 2 、 Figure 3 and Figure 7 shown, a switching device for a multi-connected air conditioner includes a base 1 and a housing 2. An electromagnetic valve group and a distribution pipeline are provided on the base 1, and the housing 2 is installed on the base 1. It further includes a top plate 3, an elastic wheel frame 4, a roller 5, a track frame 6, a hook 7, an electric winch 8 and a cable 9. The top plate 3 is located above the housing 2. Two elastic wheel frames 4 are arranged front and back on both sides of the lower end surface of the top plate 3. Springs are arranged in the middle of multiple elastic wheel frames 4. Rollers 5 are rotatably installed at the lower ends of multiple elastic wheel frames 4. Track frames 6 are installed on the left and right sides of the upper end surface of the housing 2. Tracks inclined towards the front of the housing 2 are provided on both track frames 6. The four rollers 5 are respectively in rolling connection with the tracks of the two track frames 6. Two hooks 7 are installed at the rear side of the housing 2. Two square holes are provided at the rear side of the top plate 3. The hook parts of the two hooks 7 respectively extend downward from above into the two square holes of the top plate 3 to hook the top plate 3. The electric winch 8 is installed at the rear part of the upper end surface of the housing 2. One end of the cable 9 is wound on the reel of the electric winch 8, and the other end of the cable 9 is connected to the rear part of the top plate 3. It further includes two supports 10, two columns 11 and two shock-absorbing springs 12. The two supports 10 are respectively installed at both ends of the rear side wall of the housing 2. The two columns 11 are respectively vertically installed on the two supports 10. The middle parts of the two hooks 7 are respectively hinged to the tops of the two columns 11. The lower ends of the two shock-absorbing springs 12 are respectively rotatably connected to the two supports 10, and the upper ends of the two shock-absorbing springs 12 are respectively rotatably connected to the rear ends of the two hooks 7. It further includes two limit strips 13 and two limit blocks 14. The two limit strips 13 are respectively installed on the inclined tracks of the two track frames 6. The two limit strips 13 limit and guide the multiple rollers 5. The two limit blocks 14 are respectively installed at the front parts of the two track frames 6. The two limit blocks 14 limit the forward movement distance of the two rollers 5 located at the rear part of the top plate 3, and the two limit blocks 14 limit the backward movement distance of the two rollers 5 located at the front part of the top plate 3.

[0024] Under normal conditions, two supports 10 and two columns 11 rotatably support two hooks 7. The elastic force of two shock-absorbing springs 12 keeps the two hooks 7 elastically stable, so that when the top plate 3 is reset, the hook parts of the two hooks 7 can be pushed up and extended into two square holes of the top plate 3 to hook and lock the top plate 3, keeping the top plate 3 above the outer shell 2. When it snows, the top plate 3 replaces the upper end surface of the outer shell 2 to bear the snow accumulation. As the thickness of the snow accumulation increases, its weight increases synchronously, causing the top plate 3 to gradually compress the springs in multiple elastic wheel frames 4, making the multiple elastic wheel frames 4 contract and the height of the top plate 3 decrease. When the top plate 3 drops to disengage from the two hooks 7, under the action of the component force of the gravity of the top plate 3 and the snow accumulation along the inclined tracks of the two track frames 6, multiple rollers 5 move along the inclined tracks of the two track frames 6 towards the front of the outer shell 2, thereby driving the top plate 3 to move forward relative to the outer shell 2. The front side of the top plate 3 moves out of the two track frames 6 and then flips downward, so that the snow accumulation on the top plate 3 is dumped. After the snow accumulation is cleared, the electric winch 8 operates to wind up the cable 9. The cable 9 pulls the top plate 3 back onto the outer shell 2 and makes the four rollers 5 return to their initial positions on the two track frames 6. The hook parts of the two hooks 7 extend into two square holes of the top plate 3 again to hook and lock the top plate 3; realizing the function of automatically clearing snow accumulation, avoiding the oppression and deformation of the outer shell of the switching device of the multi-split air conditioner caused by thick snow accumulation, and at the same time reducing the adverse effects on the circuits and pipelines inside the switching device of the multi-split air conditioner when the snow accumulation melts. Due to the limiting and guiding effects of two limiting strips 13, the four rollers 5 are not easily separated from the inclined tracks of the two track frames 6. Two rollers 5 located at the rear of the top plate 3 are blocked by two limiting blocks 14, so that the two rollers 5 remain on the two track frames 6. When the top plate 3 is reset, two rollers 5 located at the front of the top plate 3 are blocked by two limiting blocks 14 to position the top plate 3.

[0025] Embodiment 2

[0026] As Figure 6 shown, on the basis of Embodiment 1, it further includes a first contact switch 15 and a second contact switch 16. The first contact switch 15 is installed at the front of the track frame 6, and the second contact switch 16 is installed at the rear of the track frame 6. The contact arms of the first contact switch 15 and the second contact switch 16 extend into the tracks of the track frame 6. Both the first contact switch 15 and the second contact switch 16 are electrically connected to the controller of the electric winch 8.

[0027] When removing the snow on the top plate 3 by moving it forward, when the two rollers 5 at the rear of the top plate 3 are blocked by the two limit blocks 14, the rollers 5 contact the contact arm of the first contact switch 15. The first contact switch 15 sends a signal to the controller of the electric winch 8, causing the electric winch 8 to operate and reel in the cable 9, so that the top plate 3 starts to reset. When the top plate 3 is in place, the rollers 5 contact the contact arm of the second contact switch 16. The second contact switch 16 sends a signal to the controller of the electric winch 8, causing the electric winch 8 to stop, realizing the automatic control of the electric winch 8.

[0028] Embodiment 3

[0029] As Figure 5 shown, on the basis of Embodiment 1, it further includes two front brackets 17 and a scraper 18. The two front brackets 17 are respectively installed on both sides of the front part of the housing 2. The two ends of the scraper 18 are respectively connected to the two front brackets 17. It further includes two screws 19 and two nuts 20. Screws 19 are provided at both ends of the scraper 18. The two screws 19 are respectively movably inserted into the two front brackets 17. The two nuts 20 are respectively screwed onto the two screws 19 and locked with the two front brackets 17.

[0030] When the top plate 3 is moved out of the housing 2 for flipping, the scraper 18 scrapes the upper end surface of the top plate 3, thereby improving the effect of snow removal on the top plate 3. Rotate the scraper 18 to adjust the distance between the edge of the scraper 18 and the housing 2, thereby adjusting the gap between the edge of the scraper 18 and the upper end surface of the top plate 3. Tighten the two nuts 20 to lock the two screws 19 with the two front brackets 17, locking the scraper 18 to achieve different scraping effects on the snow.

[0031] As Figures 1 to 7As shown in the figure, a switching device for a multi-connected air conditioner of the present utility model, when it is working, first in the normal state, the hook parts of the two hooks 7 extend into the two square holes of the top plate 3 to hook and lock the top plate 3, so that the top plate 3 is kept above the outer shell 2. Then when it snows, the top plate 3 replaces the upper end face of the outer shell 2 to bear the snow accumulation. As the thickness of the snow accumulation increases, its weight increases synchronously, causing the top plate 3 to gradually compress the springs in the plurality of elastic wheel frames 4, causing the plurality of elastic wheel frames 4 to contract, and the height of the top plate 3 to decrease. When the top plate 3 drops to disengage from the two hooks 7, then under the action of the component force of the gravity of the top plate 3 and the snow accumulation along the inclined track of the track frame 6, the plurality of rollers 5 move along the inclined tracks of the two track frames 6 towards the front of the outer shell 2, thereby driving the top plate 3 to move forward towards the outer shell 2. After the front side of the top plate 3 moves out of the two track frames 6, it turns downward, so that the snow accumulation on the top plate 3 is poured out. The scraper 18 scrapes the snow accumulation on the top plate 3. The two rollers 5 located at the rear of the top plate 3 are blocked by the two limit blocks 14 and contact the first contact switch 15. The first contact switch 15 sends a signal to the controller of the electric winch 8, causing the electric winch 8 to operate to wind up the cable 9, so that the top plate 3 starts to reset. The electric winch 8 operates to wind up the cable 9, and the cable 9 pulls the top plate 3 back onto the outer shell 2 and makes the four rollers 5 return to the initial positions on the two track frames 6. Finally, when the top plate 3 is reset in place, the roller 5 contacts the contact arm of the second contact switch 16. The second contact switch 16 sends a signal to the controller of the electric winch 8, causing the electric winch 8 to stop. The elastic force of the two shock-absorbing springs 12 makes the hook parts of the two hooks 7 extend into the two square holes of the top plate 3 again to hook and lock the top plate 3.

[0032] The main functions achieved by the present utility model are:

[0033] 1. It has the function of automatically clearing snow accumulation, avoiding the adverse effects caused by snow accumulation, and having better reliability;

[0034] 2. It can automatically reset after the snow accumulation is cleared, without manual maintenance.

[0035] The installation method, connection method or setting method of a switching device for a multi-connected air conditioner of the present utility model are all common mechanical methods, and any method that can achieve its beneficial effects can be implemented; the base 1, outer shell 2, elastic wheel frame 4, roller 5, hook 7, electric winch 8, cable 9, shock-absorbing spring 12, first contact switch 15, second contact switch 16, screw 19, and nut 20 of a switching device for a multi-connected air conditioner of the present utility model are purchased on the market. Those skilled in the art only need to install and operate according to the attached user manual, without the need for creative labor from those skilled in the art.

[0036] All the technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the technical field to which this utility model pertains. The terms used in the specification of this utility model herein are only for the purpose of describing specific embodiments and are not intended to limit this utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0037] The above are only the preferred embodiments of this utility model. It should be noted that for those of ordinary skill in the technical field, without departing from the technical principle of this utility model, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of this utility model.

Claims

1. A switching device for a multi-split air conditioner, comprising a base (1) and a housing (2), wherein a solenoid valve group and a distribution pipeline are arranged on the base (1), and the housing (2) is mounted on the base (1); characterized in that: The utility model also comprises a top plate (3), an elastic wheel frame (4), a roller (5), a track frame (6), a hook (7), an electric reel (8) and a cable (9), wherein the top plate (3) is located above the outer shell (2), two elastic wheel frames (4) are arranged front and rear on both sides of the lower end surface of the top plate (3), a plurality of elastic wheel frames (4) are arranged in the middle of the plurality of elastic wheel frames (4), and rollers (5) are rotatably mounted on the lower ends of the plurality of elastic wheel frames (4), and track frames (6) are arranged on the left and right sides of the upper end surface of the outer shell (2), and the two track frames (6) are arranged with springs that are directed toward the outer shell (2). The front part of the housing (2) is provided with an inclined track, four rollers (5) are respectively connected to the tracks of the two track frames (6) in a rolling manner, two hooks (7) are installed on the rear side of the housing (2), two square holes are arranged on the rear side of the top plate (3), the hooks of the two hooks (7) extend from top to bottom into the two square holes of the top plate (3) to hook the top plate (3), an electric reel (8) is installed on the rear part of the upper end surface of the housing (2), one end of the cable (9) is reeled on the reel of the electric reel (8), and the other end of the cable (9) is connected to the rear part of the top plate (3).

2. A switching device for a multi-split air conditioner according to claim 1, characterized in that: The utility model also comprises two supports (10), two upright posts (11) and two shock absorbing springs (12), wherein the two supports (10) are respectively mounted at the two ends of the rear side wall of the housing (2), the two upright posts (11) are respectively vertically mounted on the two supports (10), the middle parts of the two hooks (7) are respectively hinged on the top ends of the two upright posts (11), the lower ends of the two shock absorbing springs (12) are respectively rotatably connected to the two supports (10), and the upper ends of the two shock absorbing springs (12) are respectively rotatably connected to the rear ends of the two hooks (7).

3. A switching device for a multi-split air conditioner according to claim 1, characterized in that: The invention also comprises two limit bars (13) and two limit blocks (14), wherein the two limit bars (13) are respectively installed on the inclined tracks of the two track frames (6), the two limit bars (13) limit and guide the plurality of rollers (5), and the two limit blocks (14) are respectively installed on the front of the two track frames (6), the two limit blocks (14) limit the forward movement distance of the two rollers (5) located at the rear of the top plate (3), and the two limit blocks (14) limit the backward movement distance of the two rollers (5) located at the front of the top plate (3).

4. A switching device for a multi-split air conditioner according to claim 1, characterized in that: The invention also comprises a contact switch 1 (15) and a contact switch 2 (16), wherein the contact switch 1 (15) is mounted on the front of the track frame (6), and the contact switch 2 (16) is mounted on the rear of the track frame (6), and the contact arms of the contact switch 1 (15) and the contact switch 2 (16) both extend into the track of the track frame (6), and the contact switch 1 (15) and the contact switch 2 (16) are both electrically connected to the controller of the electric retractor (8).

5. A switching device for a multi-split air conditioner according to claim 1, characterized in that: It also includes two front brackets (17) and a scraper (18), wherein the two front brackets (17) are respectively mounted on both sides of the front portion of the housing (2), and the two ends of the scraper (18) are respectively connected to the two front brackets (17).

6. A switching device for a multi-split air conditioner according to claim 5, characterized in that: It also includes two screw rods (19) and two nuts (20). The two ends of the scraper (18) are provided with screw rods (19). The two screw rods (19) are respectively movably inserted in the two front brackets (17). The two nuts (20) are respectively screwed on the two screw rods (19) and locked with the two front brackets (17).

Images