A filter screen device for a heat exchanger

Abstract

The application relates to a filter screen device of a heat network heater and relates to the field of heat network heater production, and comprises a liquid storage cylinder, a liquid inlet and a liquid outlet are formed in the liquid storage cylinder, the liquid inlet of the liquid storage cylinder is communicated with a water source, the liquid outlet of the liquid storage cylinder is communicated with a water inlet of the heat network heater; a filter assembly, the filter assembly comprises a filter screen, a connecting ring and a plurality of supporting rods, the plurality of supporting rods are slidably connected with the connecting ring in the circumferential direction of the connecting ring and are arranged in the radial direction of the liquid storage cylinder, the plurality of supporting rods are detachably connected with the filter screen, two supporting rods connected with two ends of the filter screen can abut against each other, a sliding groove in the circumferential direction of the liquid storage cylinder is formed in the inner wall of the liquid storage cylinder, a sliding block slidably connected with the sliding groove is fixedly connected to the supporting rod, and an opening for enabling the sliding blocks of the plurality of supporting rods to enter the sliding groove is formed in the side wall of the sliding groove; a filter screen replacement hole is formed in the side of the liquid storage cylinder away from the ground, and a cover body for opening and closing the filter screen replacement hole is arranged on the liquid storage cylinder. The application can realize the purpose that the working efficiency of the heat network heater is not easily affected.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat network heater production, and particularly relates to a filter screen device of a heat network heater. BACKGROUND

[0002] The heat network heater is a key equipment of the heat network system and is one of the main auxiliary equipments of the heat power plant. The main function of the heat network heater is to heat the circulating water in the heat network by using the steam extracted from the steam turbine or the steam (heating medium) introduced from the boiler to meet the requirements of the heat supply users.

[0003] In the related art, a heat network heater inlet filter screen device is disclosed in Chinese Patent No. CN103316517B. The filter screen main body shell is arranged inside the collection well. The filter screen front end inlet and outlet reducer is arranged at the front end of the filter screen main body shell, and the filter screen rear end inlet and outlet reducer is arranged at the rear end of the filter screen main body shell. The filter screen is a cone, and the large end of the filter screen is arranged on the filter screen rear end inlet and outlet reducer. The cross grating is arranged on one side of the filter screen front end inlet and outlet reducer. The inlet pipe is arranged on the outer wall of the collection well, and the pollution discharge door with a valve is arranged at the tail end of the collection well. The pressure gauges are arranged on the filter screen front end inlet and outlet reducer and the inlet pipe.

[0004] For the above-mentioned related art, the inventors find that the filter screen is prone to be blocked after long-term use. Therefore, the filter screen needs to be replaced by the staff. The heat network heater needs to be shut down when the staff replaces the filter screen, which reduces the working efficiency of the heat network heater. SUMMARY

[0005] In order to prevent the working efficiency of the heat network heater from being affected, the present application provides a filter screen device of a heat network heater.

[0006] The present application provides a filter screen device of a heat network heater, which relates to the following technical scheme.

[0007] The filter screen device of the heat network heater comprises:

[0008] The liquid storage cylinder is provided with a liquid inlet and a liquid outlet. The liquid inlet of the liquid storage cylinder is communicated with a water source, and the liquid outlet of the liquid storage cylinder is communicated with the water inlet of the heat network heater.

[0009] The filter assembly comprises a filter screen, a connecting ring and a plurality of support rods. The plurality of support rods are circumferentially connected with the connecting ring in a sliding manner, and the plurality of support rods are arranged radially on the liquid storage cylinder. The plurality of support rods are detachably connected with the filter screen, and the two support rods connected with the two ends of the filter screen can abut against each other. The sliding groove is arranged on the inner wall of the liquid storage cylinder in a circumferential direction. The sliding block is fixedly connected with the support rod and is connected with the sliding groove in a sliding manner. The opening is arranged on the side wall of the sliding groove for the sliding block of the plurality of support rods to enter the sliding groove.

[0010] The filter screen replacement hole is provided on the side of the liquid storage cylinder away from the ground, and a cover body for opening and closing the filter screen replacement hole is arranged on the liquid storage cylinder.

[0011] By adopting the above technical scheme, the worker inserts the plurality of support rods into the sliding groove through the opening, and then pushes the support rods at both ends to rotate towards the ground by using the auxiliary tool until the support rods at both ends abut, thereby completing the installation of the filter screen; when the worker needs to replace the filter screen, the support rods are retracted by using the auxiliary tool, and the filter assembly is disassembled, so that the filter screen can be replaced; the arrangement of the liquid storage cylinder and the filter assembly in the application enables the worker to lower the filter assembly for removal without stopping the machine, and the filter screen can be replaced, thereby realizing the purpose of not easily affecting the working efficiency of the heat network heater.

[0012] Optionally, the filter assembly is provided with two groups, and the two groups of filter assemblies are arranged on the two sides of the filter screen replacement hole.

[0013] By adopting the above technical scheme, the arrangement of the two groups of filter assemblies can enable the worker to install a new filter screen first and then replace the old filter screen when replacing the filter screen, so that the replacement of the filter screen does not easily affect the filtration of water.

[0014] Optionally, the support rods at both ends of the filter screen are a first support rod and a second support rod, a first driving assembly for driving the first support rod to slide is arranged on the side wall of the liquid storage cylinder, the first driving assembly comprises a first driving worm wheel and a first driving worm, the first driving worm wheel is fixedly connected with the first support rod, and the first driving worm is engaged with the first driving worm wheel; a second driving assembly for driving the second support rod to slide is arranged on the side wall of the liquid storage cylinder, the second driving assembly comprises a second driving worm wheel and a second driving worm, the second driving worm wheel is fixedly connected with the second support rod, and the second driving worm wheel is engaged with the second driving worm.

[0015] By adopting the above technical scheme, the first driving worm is rotated, so that the first driving worm drives the first driving worm wheel to rotate, and then the first support rod drives the filter screen to rotate towards or away from the ground, so as to realize the unfolding or retraction of the filter screen; the second driving worm is rotated, so that the second driving worm drives the second driving worm wheel to rotate, and then the second support rod drives the filter screen to rotate towards or away from the ground, so as to realize the unfolding or retraction of the filter screen.

[0016] Optionally, the first support rod and the second support rod are fixedly connected with a buffer gasket on the side surface close to each other.

[0017] By adopting the above technical scheme, the arrangement of the buffer gasket makes the abutment of the first support rod and the second support rod more compact.

[0018] Optionally, a positioning plate is fixedly connected to the outer circumferential side of the filter screen, the positioning plate is a soft plate, and the positioning plate can be inserted into the sliding groove.

[0019] By adopting the above technical scheme, the positioning plate is arranged to prevent the filter screen from being wrinkled due to gravity.

[0020] Optionally, the inlet filter screen device further comprises a fixing assembly, the fixing assembly comprises a fixing block and a fixing box, the fixing box is fixedly connected to the side wall of the liquid storage cylinder, the fixing block is slidably connected to the fixing box in a direction approaching or moving away from the filter screen and can abut against the filter screen, and the fixing box is provided with a regulating assembly for regulating the sliding of the fixing block.

[0021] By adopting the above technical scheme, the fixing assembly is arranged to improve the connection stability of the filter screen and the positioning ring and reduce the pulling force between the supporting rod and the filter screen, thereby improving the connection stability of the supporting rod and the filter screen.

[0022] Optionally, the regulating assembly comprises a regulating screw and a regulating gear, one end of the regulating screw is rotatably connected to the side wall of the fixing box, the other end of the regulating screw is threadedly connected to the fixing block, the regulating gear is coaxially and fixedly connected to the regulating screw, and the fixing box is provided with an adjusting assembly for adjusting the rotation of the regulating gear.

[0023] By adopting the above technical scheme, the adjusting assembly is controlled to rotate the regulating gear, and the fixing block cannot rotate with the regulating screw, so that the fixing block moves away from or approaches the filter screen under the action of the regulating screw.

[0024] Optionally, the adjusting assembly comprises an adjusting gear ring, an adjusting bevel gear and an adjusting bevel gear ring, the adjusting bevel gear is fixedly connected with a rotating shaft, the rotating shaft is rotatably connected to the fixing box, one end of the rotating shaft penetrates out of the fixing box, the adjusting bevel gear ring is coaxially and fixedly connected to the adjusting gear ring, and both are rotatably connected to the inner wall of the fixing box, the adjusting bevel gear ring is engaged with the adjusting bevel gear, and the adjusting gear ring is engaged with the regulating gear.

[0025] By adopting the above technical scheme, the staff holds one end of the rotating shaft penetrating out of the fixing box and rotates, so that the rotating shaft drives the adjusting bevel gear to rotate, the adjusting bevel gear ring rotates, the adjusting gear ring rotates, and finally the regulating gear rotates, and the fixing block cannot rotate with the regulating screw, so that the fixing block moves away from or approaches the filter screen under the action of the regulating screw.

[0026] In summary, the present application has at least the following beneficial technical effects:

[0027] 1. The operator inserts multiple support rods into the slide groove through the opening, and then uses an auxiliary tool to push the support rods at both ends towards the ground until the support rods at both ends touch, thus completing the installation of the filter screen; when the operator needs to replace the filter screen, the support rods are retracted using an auxiliary tool, and the filter assembly is removed; the liquid storage tank and filter assembly in this application allow the operator to remove the filter assembly and replace the filter screen without stopping the machine, thereby achieving the purpose of making the working efficiency of the heating network heater less affected;

[0028] 2. The fixed component improves the connection stability between the filter and the positioning ring, while reducing the tensile force between the support rod and the filter, thus enhancing the connection stability between the support rod and the filter. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application;

[0030] Figure 2 This is a top view of an embodiment of this application;

[0031] Figure 3 This is a schematic diagram of the connection structure between the filter component and the positioning ring in an embodiment of this application;

[0032] Figure 4 This is a partial cross-sectional view of the filtering component in an embodiment of this application;

[0033] Figure 5 This is an explosion diagram of the first and second protective shields in the embodiments of this application;

[0034] Figure 6 This is a partial cross-sectional view of the fixing component in an embodiment of this application.

[0035] Explanation of reference signs: 100, liquid storage cylinder; 110, liquid inlet; 120, liquid outlet; 130, filter screen replacement hole; 140, positioning ring; 141, sliding groove; 200, filter assembly; 210, filter screen; 211, positioning plate; 220, connecting ring; 230, support rod; 231, first support rod; 232, second support rod; 233, intermediate support rod; 234, sliding block; 235, buffer gasket; 300, first protective cover; 310, first driving assembly; 311, first driving worm; 312, first driving worm wheel; 313, first connecting rod; 314, first rotating groove; 320, first connecting hole; 321, first sealing strip; 400, second protective cover; 410, second driving assembly; 411, second driving worm; 412, second driving worm wheel; 413, second connecting rod; 414, second rotating groove; 420, second connecting hole; 421, second sealing strip; 500, fixing assembly; 510, fixing block; 520, fixing box; 600, regulating assembly; 610, regulating screw; 620, regulating gear; 700, adjusting assembly; 710, adjusting gear ring; 720, adjusting bevel gear ring; 730, adjusting bevel gear; 731, rotating shaft; 732, handle. DETAILED DESCRIPTION

[0036] The following will be described in detail below with reference to the accompanying drawings. Figures 1-2 The present application is further described in detail.

[0037] The embodiment of the present application discloses a filter screen device of a heat network heater. Referring to Figure 1 and Figure 2 , the filter screen device comprises a liquid storage cylinder 100 and a filter assembly 200 arranged in the liquid storage cylinder 100.

[0038] The liquid storage cylinder 100 is provided with a liquid inlet 110 and a liquid outlet 120, and the liquid inlet 110 and the liquid outlet 120 are arranged on opposite sides of the filter assembly 200. The liquid inlet 110 of the liquid storage cylinder 100 is used for being communicated with a water source, the liquid outlet 120 of the liquid storage cylinder 100 is communicated with a water inlet end of the heat network heater, so as to supply water into the heat network heater; a filter screen replacement hole 130 is arranged on the side of the liquid storage cylinder 100 away from the ground, so as to facilitate a worker to replace the filter assembly 200, a cover body for plugging the filter screen replacement hole 130 is arranged on the liquid storage cylinder 100, and the cover body and the liquid storage cylinder 100 are connected through a plurality of bolts.

[0039] Referring to Figure 2 and Figure 3 , the filter assembly 200 comprises a filter screen 210, a connecting ring 220 and a plurality of support rods 230.

[0040] The filter screen 210 is detachably connected with the plurality of support rods 230 through bolts.

[0041] The support rods 230 are provided in the embodiment, and there are 9 support rods 230. The support rods 230 at two ends are respectively a first support rod 231 and a second support rod 232. The support rods 230 at middle positions are middle support rods 233. The middle support rods 233 are fixedly connected with the connecting ring 220. In other embodiments, the middle support rods 233 can also be slidably connected with the connecting ring 220. The remaining support rods 230 are all slidably connected with the connecting ring 220 in the circumferential direction of the connecting ring 220, and the support rods 230 all extend in the radial direction of the connecting ring 220. The filter screen 210 is circular after alignment at two ends. The plurality of support rods 230 are detachably connected with the filter screen 210 and are uniformly arranged in the circumferential direction of the filter screen 210. The first support rod 231 and the second support rod 232 are separately arranged at two ends of the filter screen and are fixedly connected with the filter screen 210.

[0042] The inner wall of the liquid storage cylinder 100 is fixedly connected with a positioning ring 140. The inner circumferential wall of the positioning ring 140 is provided with a sliding groove 141 in the axial direction, and the sliding groove 141 is an L-shaped groove. The support rod 230 is fixedly connected with a sliding block 234 matched with the shape of the sliding groove 141, and the sliding block 234 is slidably connected with the side wall of the sliding groove 141. The positioning ring 140 is provided with an opening for the sliding blocks 234 of the plurality of support rods 230 to enter the sliding groove 141, and the opening is located below the filter screen replacement hole 130.

[0043] In order to prevent the filter screen from being wrinkled, the positioning plate 211 is fixedly connected to the circumferential side of the filter screen 210. The positioning plate 211 is fixedly connected to the side of the sliding block 234 close to the groove bottom of the sliding groove 141, so that the positioning plate 211 can be inserted into the sliding groove 141. In the application, the positioning plate 211 is a rubber plate, so that the positioning plate 211 is soft and does not easily interfere with the folding of the filter screen 210.

[0044] Referring to Figure 4 and Figure 5The first protective cover 300 is fixedly connected to the connecting ring 220 and is a cuboid box. A first driving assembly 310 for driving the first supporting rod 231 to slide is arranged on the connecting ring 220. The first driving assembly 310 comprises a first driving worm gear 312 and a first driving worm 311. The first driving worm gear 312 is rotatably connected to the side wall of the first protective cover 300 at both ends, and one end of the first driving worm gear 312 close to the middle supporting rod 233 penetrates out of the first protective cover 300 and is sealingly rotatably connected to the side wall of the first protective cover 300. A first rotating groove 314 is arranged at the end of the first driving worm gear 312 penetrating out of the first protective cover 300. A first connecting rod 313 is fixedly connected to the first driving worm gear 312, and the first connecting rod 313 is fixedly connected to the first supporting rod 231 away from the first driving worm gear 312. A first connecting hole 320 is arranged on the first protective cover 300 for the first connecting rod 313 to penetrate out of. In order to prevent water from entering the first protective cover 300, a first sealing strip 321 is arranged on the first protective cover 300. The first sealing strip 321 is sleeved on the first connecting rod 313 and is slidingly connected to the first protective cover 300. The sliding track of the first sealing strip 321 is arranged along the moving track of the first connecting rod 313.

[0045] The second protective cover 400 is fixedly connected to the connecting ring 220 and is a cuboid box. The second protective cover 400 is fixedly connected to the first protective cover 300 away from the filter screen 210. A second driving assembly 410 for driving the second supporting rod 232 to slide is arranged on the connecting ring 220. The second driving assembly 410 comprises a second driving worm gear 412 and a second driving worm 411. The second driving worm gear 412 is rotatably connected to the side wall of the second protective cover 400 at both ends, and one end of the second driving worm gear 412 close to the middle supporting rod 233 penetrates out of the second protective cover 400 and is sealingly rotatably connected to the side wall of the second protective cover 400. A second rotating groove 414 is arranged at the end of the second driving worm gear 412 penetrating out of the second protective cover 400. A second connecting rod 413 is fixedly connected to the second driving worm gear 412 away from the second supporting rod 232. A second connecting hole 420 is arranged on the second protective cover 400 for the second connecting rod 413 to penetrate out of. In order to prevent water from entering the second protective cover 400, a second sealing strip 421 is arranged on the second protective cover 400. The second sealing strip 421 is sleeved on the second connecting rod 413 and is slidingly connected to the second protective cover 400. The sliding track of the second sealing strip 421 is arranged along the moving track of the second connecting rod 413.

[0046] In order to prevent the filtering effect of water from being affected by the replacement of the filter screen 210 by the staff, two groups of filter assemblies 200 are arranged in the application, and the two groups of filter assemblies 200 are arranged on both sides of the filter screen replacement hole 130.

[0047] Referring to Figure 4 and Figure 6 In order to improve the support stability of the filter screen 210, the filter screen device further comprises a fixing assembly 500, the fixing assembly 500 comprises an annular fixing block 510 and a fixing box 520, the fixing box 520 is fixedly connected with the inner wall of the liquid storage cylinder 100 and is located on the side of the filter screen 210 away from the first protective cover 300, and the fixing box 520 is arranged in a spaced manner with the filter screen 210. The fixing block 510 is sealingly and slidingly connected with the fixing box 520 in the direction of approaching or moving away from the filter screen 210, and the fixing box 520 is provided with a regulating assembly 600 for regulating the sliding distance of the fixing block 510.

[0048] The regulating assembly 600 is specifically arranged as follows: the regulating assembly 600 comprises a plurality of regulating screws 610 and a plurality of regulating gears 620, the plurality of regulating gears 620 are uniformly arranged in the circumferential direction of the fixing box 520, and one end of the regulating screw 610 is rotationally connected with the fixing box 520 and the other end is threadedly connected with the fixing block 510. The regulating gear 620 corresponds to the regulating screw 610 in one-to-one correspondence, and the regulating gear 620 is fixedly connected with the corresponding regulating screw 610 in a coaxial manner.

[0049] The fixing box 520 is provided with an adjusting assembly 700 for adjusting the rotation of the regulating gear 620, the adjusting assembly 700 comprises an adjusting gear ring 710, an adjusting bevel gear ring 720 and an adjusting bevel gear 730, the adjusting bevel gear 730 is fixedly connected with a rotating shaft 731, the rotating shaft 731 penetrates out of the fixing box 520 and is sealingly and rotationally connected with the side wall of the fixing box 520, and one end of the rotating shaft 731 penetrating out of the fixing box 520 is fixedly connected with a handle 732. The adjusting bevel gear ring 720 is fixedly connected with the adjusting gear ring 710 in a coaxial manner and is rotationally connected with the side wall of the fixing box 520, the adjusting bevel gear ring 720 is engaged with the adjusting bevel gear 730, and the adjusting gear ring 710 is engaged with the regulating gear 620.

[0050] When the adjusting bevel gear 730 is twisted by the staff, the adjusting bevel gear 730 drives the adjusting bevel gear ring 720 to rotate, that is, the adjusting gear ring 710 rotates and drives the regulating gear 620 to rotate, so that the regulating screw 610 drives the fixing block 510 to move in the direction of approaching or moving away from the filter screen 210.

[0051] The implementation principle of the embodiment of the application is that after the staff connects the liquid storage cylinder 100 with the water source and the heat network heater, inserts a plurality of supporting rods 230 into the sliding groove 141 through the opening, then inserts a tool into the first rotating groove 314, so that the first driving worm 311 rotates and drives the first driving worm wheel 312 to rotate and drive the first supporting rod 231 to rotate, when the first supporting rod 231 is rotated to the position, inserts the tool into the second rotating groove 414, so that the second driving worm 411 rotates and drives the second driving worm wheel 412 to rotate and drive the second supporting rod 232 to rotate, until the side surfaces of the first supporting rod 231 and the second supporting rod 232 abut, thereby completing the supporting of the filter screen 210, finally holds the handle 732 to move the fixed block 510 to the direction close to the filter screen 210, until the fixed block 510 abuts with the filter screen 210, thereby completing the installation of the filtering device; when the staff needs to replace the filter screen 210, the supporting rod 230 and the fixed block 510 are retracted, finally the filtering assembly 200 is disassembled, and the filter screen 210 can be replaced.

[0052] The above are preferred embodiments of the application, and do not limit the protection scope of the application, so: equivalent changes made according to the structure, shape, principle of the application should be covered in the protection scope of the application.

Claims

1. A filter device for a heating network heater, characterized in that, include: A liquid storage cylinder (100) is provided with an inlet (110) and a outlet (120). The inlet (110) of the liquid storage cylinder (100) is connected to a water source, and the outlet (120) of the liquid storage cylinder (100) is connected to the water inlet of the heating network heater. A filter assembly (200) includes a filter screen (210), a connecting ring (220), and multiple support rods (230). The multiple support rods (230) are slidably connected to the connecting ring (220) along the circumference of the connecting ring (220), and the multiple support rods (230) are arranged radially along the liquid storage cylinder (100). The multiple support rods (230) are detachably connected to the filter screen (210), and the two support rods (230) connected to both ends of the filter screen (210) can abut against each other. A sliding groove (141) is provided on the inner wall of the liquid storage cylinder (100) along its circumference. A slider (234) is fixedly connected to the support rod (230) and slidably connected to the sliding groove (141). An opening is provided on the side wall of the sliding groove (141) for the sliders (234) of the multiple support rods (230) to enter the sliding groove (141). The liquid storage cylinder (100) has a filter replacement hole (130) on the side away from the ground, and the liquid storage cylinder (100) is provided with a cover (131) for opening and closing the filter replacement hole (130).

2. The filter device for a heat exchanger heater according to claim 1, characterized in that, The filter assembly (200) is provided in two sets, and the two sets of filter assemblies (200) are respectively located on both sides of the filter replacement hole (130).

3. The filter device for a heat exchanger heater according to claim 1, characterized in that, The support rods (230) located at both ends of the filter screen (210) are respectively the first support rod (231) and the second support rod (232). The connecting ring (220) is provided with a first drive assembly (310) for driving the first support rod (231) to slide. The first drive assembly (310) includes a first drive worm gear (312) and a first drive worm (311). The first drive worm gear (312) is fixedly connected to the first support rod (231), and the first drive worm (311) meshes with the first drive worm gear (312). The first drive worm gear (312) and the first drive worm... The drive worm (311) is rotatably connected to the connecting ring (220); the connecting ring (220) is provided with a second drive assembly (410) for driving the second support rod (232) to slide. The second drive assembly (410) includes a second drive worm wheel (412) and a second drive worm (411). The second drive worm wheel (412) is fixedly connected to the second support rod (232), and the second drive worm wheel (412) meshes with the second drive worm (411). The second drive worm wheel (412) and the second drive worm (411) are both rotatably connected to the connecting ring (220).

4. The filter device for a heat exchanger heater according to claim 3, characterized in that, Buffer pads (235) are fixedly connected to the sides of the first support rod (231) and the second support rod (232) that are close to each other.

5. The filter device for a heating network heater according to claim 1, characterized in that, A positioning plate (211) is fixedly connected to the outer periphery of the filter screen (210). The positioning plate (211) is a flexible plate and can be inserted into the slide groove (141).

6. The filter device for a heat exchanger heater according to claim 1, characterized in that, The filter device further includes a fixing component (500), which includes a fixing block (510) and a fixing box (520). The fixing box (520) is fixedly connected to the side wall of the liquid storage cylinder (100). The fixing block (510) is slidably connected to the fixing box (520) in a direction close to or away from the filter (210) and can abut against the filter (210). The fixing box (520) is provided with a regulating component (600) for regulating the sliding of the fixing block (510).

7. The filter device for a heating network heater according to claim 6, characterized in that, The control assembly (600) includes a control screw (610) and a control gear (620). One end of the control screw (610) is rotatably connected to the side wall of the fixed box (520), and the other end is threadedly connected to the fixed block (510). The control gear (620) is coaxially fixedly connected to the control screw (610). The fixed box (520) is provided with a control assembly (700) for adjusting the rotation of the control gear (620).

8. The filter device for a heating network heater according to claim 7, characterized in that, The adjustment assembly (700) includes an adjustment gear ring (710), an adjustment bevel gear (730), and an adjustment bevel gear ring (720). A rotating shaft (731) is fixedly connected to the adjustment bevel gear (730). The rotating shaft (731) is rotatably connected to the fixed box (520), and one end of the rotating shaft (731) extends out of the fixed box (520). The adjustment bevel gear ring (720) and the adjustment gear ring (710) are coaxially fixedly connected, and both are rotatably connected to the inner wall of the fixed box (520). The adjustment bevel gear ring (720) meshes with the adjustment bevel gear (730), and the adjustment gear ring (710) meshes with the control gear (620).

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