Sewage treatment equipment with anti-blocking filter

Abstract

The invention discloses sewage treatment equipment with an anti-blocking filter. The sewage treatment equipment comprises a filtering assembly, a scraping assembly and a feeding assembly, the filtering assembly is used for preliminarily filtering large-particle impurities in sewage, the scraping assembly is used for scraping the intercepted impurities to prevent long-time accumulation and blockage, and the feeding assembly is used for conveying the scraped impurities to the bottom of the filtering box in time. Through cooperative work of the transmission unit and the conveying unit, convenient conveying and timely pollution discharge of scraped impurities are achieved, through transmission of a series of bevel gears, power is transmitted to the conveying unit, a second rotating shaft and a spiral conveying blade are driven to rotate, the impurities in a material gathering groove are conveyed to the bottom of a filtering box, and the filtering efficiency is improved. Impurities can be discharged in time, so that the impurities are prevented from being accumulated in the filter box, the normal operation of the filter is further guaranteed, and meanwhile, the automation degree of the whole filter system is also improved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to sewage treatment equipment with an anti-clogging filter. Background Art

[0002] The filtration device for sewage treatment is a precision equipment that uses a filter to directly intercept impurities in sewage, remove suspended matter and particulate matter in the water, reduce turbidity, reduce system dirt, bacteria, algae, rust, etc., and perform preliminary filtration and treatment of sewage.

[0003] For the current sewage filter, such as a sewage treatment filter device disclosed in the Chinese patent publication number "CN119143214B", it uses a catalytic filter element to perform preliminary impurity filtration on the sewage. Not only is the filtration contact area for the sewage small, the filtration effect is slow, and when cleaning the surface of the catalytic filter element, it needs to be cleaned gradually from the beginning to the end, which is very inefficient. When the surface of the catalytic filter element is blocked, it cannot be cleaned in time, further affecting the discharge of impurities, and easily causing incomplete sewage treatment. Accordingly, the present invention proposes a sewage treatment device with an anti-blocking filter. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a sewage treatment device with an anti-clogging filter.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A sewage treatment device with an anti-clogging filter comprises a filtering component, a scraping component and a feeding component; The filter assembly is used for preliminary filtering of large particle impurities in sewage, and the filter assembly includes a support base and a filter box fixed on the top of the support base, the filter assembly includes a support base and a filter box fixed on the top of the support base, a collection tank is fixedly connected below the filter box and located on the support base, a biological treatment tank connected to the filter box is fixedly arranged on the top of the support base and located on one side of the filter box, a layered double tank connected to the biological treatment tank is fixedly arranged on the top of the support base and located on the side of the biological treatment tank away from the filter box, and a chemical disinfection tank connected to the layered double tank is fixedly connected below the layered double tank and located on the support base; A sealing cover plate is fixedly connected to the top of the filter box, a first fixing ring is fixedly connected to the inside of the filter box, and a second fixing ring is fixedly connected to the end of the filter box away from the first fixing ring; The scraping assembly is used to scrape the intercepted impurities to prevent long-term accumulation and clogging, and the scraping assembly includes a first rotating shaft rotatably connected between the sealing cover plate and the second fixing ring; The feeding assembly is used to timely convey the scraped impurities to the bottom of the filter box. The feeding assembly consists of a transmission unit and a conveying unit. The transmission unit includes a fixed sleeve fixedly connected to the bottom of the sealing cover plate and located inside the filter box.

[0006] Preferably, a first fixed block is fixedly connected to the first rotating shaft, a second fixed block is fixedly connected to the side of the first rotating shaft away from the first fixed block, three first fixed columns are fixedly connected to the first fixed block, three second fixed columns are fixedly connected to the second fixed block, a cleaning scraper is fixedly connected between each of the first fixed columns and an adjacent second fixed column, and a material collection groove is provided inside the three cleaning scrapers.

[0007] Preferably, the fixing sleeve and the first fixing block are rotatably connected, the bottom of the fixing sleeve is fixedly provided with a first gear located inside the first fixing block, the first fixing block has one side close to the three first fixing columns and is rotatably connected to the second gear, the tops of the three second gears are fixedly connected to the first bevel gear, the three first fixing columns are rotatably connected to the first rotating rod extending into the first fixing block, the three first rotating rods have one side close to the three first bevel gears and are fixedly connected to the second bevel gears, the three first rotating rods are located inside the three first fixing columns and are fixedly connected to the third bevel gears, the tops of the three first fixing columns are fixedly connected to the first waterproof box, the three first waterproof boxes are rotatably connected to the second rotating rod extending into the three first fixing columns, the bottoms of the three second rotating rods are fixedly connected to the fourth bevel gear, the tops of the three second rotating rods are fixedly connected to the fifth bevel gear, and the three first waterproof boxes have one side close to the fifth bevel gear and are rotatably connected to the sixth bevel gear.

[0008] Preferably, the conveying unit includes a second waterproof box fixedly connected to the top of the material collecting trough, the interior of the second waterproof box is rotatably connected to a seventh bevel gear fixedly connected to the sixth bevel gear, the interior of the second waterproof box is rotatably connected to an eighth bevel gear on one side close to the seventh bevel gear, the bottom of the eighth bevel gear is fixedly connected to a second rotating shaft that extends to the outside of the second waterproof box and is rotatably connected to the second waterproof box, the second rotating shaft is fixedly connected to a spiral conveying blade, and the second rotating shaft and the spiral conveying blade are both located on the inner side of the material collecting trough.

[0009] Preferably, a water inlet is fixedly provided on the filter box, a water outlet is fixedly provided on a side of the filter box away from the water inlet, and a filter net is fixedly connected between the first fixing ring and the second fixing ring.

[0010] Preferably, a scraping motor is fixedly connected to the top of the sealing cover plate, and a driving end of the scraping motor is fixedly connected to the first rotating shaft.

[0011] Preferably, the first gear meshes with the three second gears, the first bevel gear meshes with the second bevel gear, the third bevel gear meshes with the fourth bevel gear, the fifth bevel gear meshes with the sixth bevel gear, and the seventh bevel gear meshes with the eighth bevel gear.

[0012] The present invention has the following beneficial effects: 1. By setting up the filtering components, large particles of impurities in sewage can be effectively intercepted. The reasonable setting of the water inlet and outlet allows the water flow to be filtered through the filter in an orderly manner, thereby purifying the water quality and meeting the water quality requirements of various water use scenarios. For example, in industrial production, it can effectively filter impurities in cooling water to ensure the normal operation of equipment. In domestic water use, it can preliminarily filter out large particles of impurities in sewage.

[0013] 2. By setting up a scraping assembly, the first rotating shaft can be driven to rotate by a scraping motor, and the first fixed block and the second fixed block on the first rotating shaft rotate accordingly, and the first fixed column and the second fixed column fixed thereon also rotate together, thereby driving the cleaning scraper to rotate. The cleaning scraper can scrape off the impurities intercepted on the filter net during the rotation process, and the collection tank opened inside it can collect the scraped impurities in a centralized manner. This automatic scraping process of impurities does not require frequent manual cleaning, which not only saves labor costs, but also ensures the continuous and stable operation of the filter, greatly improving the filtration efficiency and the service life of the equipment.

[0014] 3. By setting up the feeding assembly, the transmission unit and the conveying unit can work together to realize the convenient conveying and timely sewage discharge of the scraped impurities. The first gear at the bottom of the fixed sleeve is meshed with the second gear inside the first fixed block. The power is transmitted to the conveying unit through a series of bevel gears. The seventh bevel gear in the second waterproof box of the conveying unit is meshed with the eighth bevel gear, driving the second rotating shaft and the spiral conveying blade to rotate, and the impurities in the aggregate trough are conveyed to the bottom of the filter box. The collection tank at the bottom of the filter box can discharge the impurities in time under the control of the biological treatment tank, avoiding the accumulation of impurities in the filter box, further ensuring the normal operation of the filter, and also improving the automation degree of the whole filtration system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the main structure of a sewage treatment device with an anti-clogging filter proposed by the present invention; Figure 2 It is a schematic diagram of the structure inside the filter box of the present invention; Figure 3 It is a schematic diagram of the structure inside the filter screen of the present invention; Figure 4 It is a structural schematic diagram of the scraping component in the present invention; Figure 5 It is a schematic diagram of the structure inside the first fixing block in the present invention; Figure 6 It is a schematic diagram of the structure inside the first waterproof box of the present invention; Figure 7 It is a schematic diagram of the structure inside the second waterproof box of the present invention; Figure 8 for Figure 5 Schematic diagram of the enlarged structure of A.

[0016] In the figure: 1 support base, 2 filter box, 3 sealing cover, 4 collection tank, 5 biological treatment tank, 6 water inlet, 7 water outlet, 8 first fixed ring, 9 second fixed ring, 10 filter screen, 11 first rotating shaft, 12 first fixed block, 13 second fixed block, 14 first fixed column, 15 second fixed column, 16 cleaning scraper, 17 aggregate trough, 18 fixed sleeve, 19 first gear, 20 second gear, 21 first bevel gear, 22 first rotating rod, 23 second bevel gear, 24 third bevel gear, 25 first waterproof box, 26 second rotating rod, 27 fourth bevel gear, 28 fifth bevel gear, 29 sixth bevel gear, 30 second waterproof box, 31 seventh bevel gear, 32 eighth bevel gear, 33 second rotating shaft, 34 spiral conveying blade, 35 scraping motor, 36 layered double tank, 37 chemical disinfection tank. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Embodiment 1:

[0018] Reference Figure 1-Figure 3 , a sewage treatment device with an anti-clogging filter, comprising a filtering component, a scraping component and a feeding component; The filter assembly is used for preliminary filtering of large particle impurities in sewage, and the filter assembly includes a support base 1 and a filter box 2 fixed on the top of the support base 1, the filter assembly includes a support base 1 and a filter box 2 fixed on the top of the support base 1, a collection tank 4 is fixedly connected below the filter box 2 and located on the support base 1, a biological treatment tank 5 connected to the filter box 2 is fixedly arranged on the top of the support base 1 and located on one side of the filter box 2, a layered double tank 36 connected to the biological treatment tank 5 is fixedly arranged on the top of the support base 1 and located on the side of the biological treatment tank 5 away from the filter box 2, and a chemical disinfection tank 37 connected to the layered double tank 36 is fixedly connected below the layered double tank 36 and located on the support base 1; A sealing cover plate 3 is fixedly connected to the top of the filter box 2, a first fixing ring 8 is fixedly connected to the inside of the filter box 2, and a second fixing ring 9 is fixedly connected to the end of the filter box 2 away from the first fixing ring 8; The scraping assembly is used to scrape the intercepted impurities to prevent long-term accumulation and clogging. The scraping assembly includes a first rotating shaft 11 rotatably connected between the sealing cover plate 3 and the second fixing ring 9; The feeding assembly is used to timely convey the scraped impurities to the bottom of the filter box 2. The feeding assembly is composed of a transmission unit and a conveying unit. The transmission unit includes a fixed sleeve 18 fixedly connected to the bottom of the sealing cover plate 3 and located inside the filter box 2. A water inlet 6 is fixedly provided on the filter box 2, a water outlet 7 is fixedly provided on a side of the filter box 2 away from the water inlet 6, and a filter screen 10 is fixedly connected between the first fixing ring 8 and the second fixing ring 9; In this embodiment, a sealing cover plate 3 is installed on the top of the filter box 2, and a tight seal is achieved through sealing materials such as a rubber sealing ring to prevent external impurities from entering from the top during the operation of the equipment, thereby ensuring that the filtering effect is not affected. At the same time, a biological treatment tank 5 is installed on the collection tank 4, and the biological treatment tank 5 is connected to the control system to realize remote or automatic control of sewage discharge operations. The material and mesh size of the filter screen 10 are selected according to actual filtering needs. When filtering larger particle impurities in industrial sewage, a stainless steel wire mesh with a slightly larger mesh can be selected. In domestic sewage filtration, a finer filtering material, such as a polypropylene melt-blown filter element, can be used to effectively intercept tiny particle impurities. Furthermore, when water containing impurities flows into the filter box 2 from the water inlet 6, due to the reasonable setting of the water inlet 6 and the water outlet 7 and the principle of water flow dynamics, the water flow can pass through the inside of the filter box 2 in an orderly manner. When passing through the filter screen 10 between the first fixing ring 8 and the second fixing ring 9, the impurities in the water are intercepted by the filter screen 10. For example, in industrial production, metal debris, mud and other impurities in the cooling water are blocked by the filter screen 10, thereby ensuring the normal operation of the pipes and equipment in the equipment cooling system and preventing impurities from causing wear or blockage to the equipment. Embodiment 2:

[0019] Reference Figure 3-Figure 5 Compared with the first embodiment, in this embodiment, a first fixed block 12 is fixedly connected to the first rotating shaft 11, a second fixed block 13 is fixedly connected to the side of the first rotating shaft 11 away from the first fixed block 12, three first fixed columns 14 are fixedly connected to the first fixed block 12, and three second fixed columns 15 are fixedly connected to the second fixed block 13. A cleaning scraper 16 is fixedly connected between each first fixed column 14 and an adjacent second fixed column 15, and a material collecting trough 17 is opened inside the three cleaning scrapers 16.

[0020] In this embodiment, the scraping motor 35 is started, and the power output by the scraping motor 35 is transmitted to the first rotating shaft 11 through connecting parts such as couplings, driving the first rotating shaft 11 to rotate. The rotation of the first rotating shaft 11 drives the first fixed block 12 and the second fixed block 13 thereon to rotate synchronously. Since the first fixed column 14 is fixed on the first fixed block 12 and the second fixed column 15 is fixed on the second fixed block 13, the first fixed column 14 and the second fixed column 15 also rotate accordingly, thereby driving the cleaning scraper 16 to make a circular motion around the first rotating shaft 11.

[0021] Furthermore, during the rotation of the cleaning scraper 16, its edge closely fits the surface of the filter 10 to scrape off the impurities intercepted on the filter. As the cleaning scraper 16 continues to rotate, the scraped impurities are collected in the collection trough 17 opened inside it. This automatic scraping of impurities function eliminates the need for frequent manual cleaning of the filter 10, greatly saving labor costs. At the same time, it effectively prevents clogging caused by long-term accumulation of impurities on the filter, ensuring that the filter can operate continuously and stably, and improving the filtration efficiency and service life of the equipment. In a sewage treatment plant, sewage contains a large amount of suspended matter, organic matter and other impurities. Traditional filters are prone to frequent shutdowns for cleaning due to clogging by impurities, while the scraping component of the external scraper filter can clean impurities in real time to ensure the continuous and stable operation of the sewage treatment system. Embodiment three:

[0022] Reference Figure 6-Figure 8Compared with the first and second embodiments, in the present embodiment, the fixing sleeve 18 and the first fixing block 12 are rotatably connected, the bottom of the fixing sleeve 18 and the first fixing block 12 are fixedly provided with a first gear 19, the first fixing block 12 is rotatably connected to one side close to the three first fixing columns 14, the tops of the three second gears 20 are all fixedly connected to the first bevel gears 21, the insides of the three first fixing columns 14 are all rotatably connected to the first rotating rods 22 extending through the inside of the first fixing block 12, and the three first rotating rods 22 are all fixedly connected to the one side close to the three first bevel gears 21 There is a second bevel gear 23, and the three first rotating rods 22 are fixedly connected to the third bevel gear 24 on one side inside the three first fixed columns 14, and the tops of the three first fixed columns 14 are fixedly connected to the first waterproof box 25, and the insides of the three first waterproof boxes 25 are all rotatably connected to the second rotating rods 26 that extend through the insides of the three first fixed columns 14, and the bottoms of the three second rotating rods 26 are fixedly connected to the fourth bevel gear 27, and the tops of the three second rotating rods 26 are fixedly connected to the fifth bevel gear 28, and the insides of the three first waterproof boxes 25 are all rotatably connected to the sixth bevel gear 29 near the fifth bevel gear 28.

[0023] The conveying unit includes a second waterproof box 30 fixedly connected to the top of the material collecting trough 17, the interior of the second waterproof box 30 is rotatably connected to a seventh bevel gear 31 fixedly connected to the sixth bevel gear 29, the interior of the second waterproof box 30 is rotatably connected to an eighth bevel gear 32 on one side close to the seventh bevel gear 31, the bottom of the eighth bevel gear 32 is fixedly connected to a second rotating shaft 33 that extends through and extends to the outside of the second waterproof box 30 and is rotatably connected to the second waterproof box 30, a spiral conveying blade 34 is fixedly connected to the second rotating shaft 33, and the second rotating shaft 33 and the spiral conveying blade 34 are both located on the inner side of the material collecting trough 17.

[0024] The first gear 19 meshes with the three second gears 20 , the first bevel gear 21 meshes with the second bevel gear 23 , the third bevel gear 24 meshes with the fourth bevel gear 27 , the fifth bevel gear 28 meshes with the sixth bevel gear 29 , and the seventh bevel gear 31 meshes with the eighth bevel gear 32 .

[0025] In this embodiment, when the first fixed block 12 rotates, since the first gear 19 and the second gear 20 inside the first fixed block 12 are meshed with each other, the second gear 20 starts to rotate driven by the first gear 19, and the first bevel gear 21 fixedly connected to the top of the second gear 20 also rotates synchronously, the first bevel gear 21 and the second bevel gear 23 fixedly connected to one end of the first rotating rod 22 are meshed with each other, thereby driving the first rotating rod 22 to rotate, the third bevel gear 24 fixedly connected to one side of the first rotating rod 22 located inside the first fixed column 14 rotates with the first rotating rod 22, the third bevel gear 24 and the fourth bevel gear 27 fixedly connected to the bottom of the second rotating rod 26 are meshed with each other, driving the second rotating rod 26 to rotate inside the first waterproof box 25, the fifth bevel gear 28 fixedly connected to the top of the second rotating rod 26 rotates, the fifth bevel gear 28 and the sixth bevel gear 29 inside the first waterproof box 25 are meshed with each other, and the power is transmitted to the conveying unit.

[0026] Furthermore, in the conveying unit, the rotation of the sixth bevel gear 29 drives the seventh bevel gear 31 fixedly connected thereto to rotate inside the second waterproof box 30, and the seventh bevel gear 31 meshes with the eighth bevel gear 32 to drive the eighth bevel gear 32 to rotate, and the second rotating shaft 33 fixedly connected to the bottom of the eighth bevel gear 32 rotates accordingly, and the spiral conveying blade 34 fixedly connected to the second rotating shaft 33 also starts to rotate. During the rotation process, the spiral conveying blade 34 conveys the impurities in the material trough 17 to the bottom of the filter box 2. When the impurities are conveyed to the bottom of the filter box 2, the control system sends a signal to open the biological treatment tank 5 according to a preset time interval or impurity accumulation amount and other conditions, and the impurities are discharged from the filter box 2 through the collection tank 4. This design enables impurities to be processed quickly and efficiently, avoids the accumulation of impurities in the filter box, further ensures the normal operation of the filter, and improves the degree of automation of the entire filtration system. For example, in the sewage generated by chemical production, the filtered chemical impurities may be corrosive or toxic. Discharging these impurities in time can prevent them from causing harm to the filtration equipment and the surrounding environment, thereby ensuring the safety and stability of the production process.

[0027] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A sewage treatment device with an anti-clogging filter, comprising a filtering component, a scraping component and a feeding component, It is characterized by: The filter assembly is used for preliminary filtering of large particle impurities in sewage, and comprises a support base (1) and a filter box (2) fixed on the top of the support base (1); a collection tank (4) is fixedly connected below the filter box (2) and located on the support base (1); a biological treatment tank (5) in communication with the filter box (2) is fixedly arranged on the top of the support base (1) and located on one side of the filter box (2); a layered double tank (36) in communication with the biological treatment tank (5) is fixedly arranged on the top of the support base (1) and located on a side of the biological treatment tank (5) away from the filter box (2); and a chemical disinfection tank (37) in communication with the layered double tank (36) is fixedly connected below the layered double tank (36) and located on the support base (1); A sealing cover plate (3) is fixedly connected to the top of the filter box (2), a first fixing ring (8) is fixedly connected to the inside of the filter box (2), and a second fixing ring (9) is fixedly connected to the end of the inside of the filter box (2) away from the first fixing ring (8); The scraping assembly is used to scrape off the intercepted impurities to prevent long-term accumulation and clogging, and the scraping assembly comprises a first rotating shaft (11) rotatably connected between the sealing cover plate (3) and the second fixing ring (9); The feeding assembly is used to promptly convey the scraped impurities to the bottom of the filter box (2), and the feeding assembly is composed of a transmission unit and a conveying unit, wherein the transmission unit comprises a fixing sleeve (18) fixedly connected to the bottom of the sealing cover plate (3) and located inside the filter box (2).

2. A sewage treatment equipment with an anti-clogging filter according to claim 1, characterized in that: A first fixed block (12) is fixedly connected to the first rotating shaft (11); a second fixed block (13) is fixedly connected to the side of the first rotating shaft (11) away from the first fixed block (12); three first fixed columns (14) are fixedly connected to the first fixed block (12); three second fixed columns (15) are fixedly connected to the second fixed block (13); a cleaning scraper (16) is fixedly connected between each of the first fixed columns (14) and an adjacent second fixed column (15); and a material collecting trough (17) is provided inside each of the three cleaning scrapers (16).

3. A sewage treatment equipment with an anti-clogging filter according to claim 2, characterized in that: The fixing sleeve (18) and the first fixing block (12) are rotatably connected. A first gear (19) is fixedly arranged at the bottom of the fixing sleeve (18) and located inside the first fixing block (12). A second gear (20) is rotatably connected to one side of the first fixing block (12) close to the three first fixing columns (14). The tops of the three second gears (20) are fixedly connected to a first bevel gear (21). The insides of the three first fixing columns (14) are rotatably connected to a first rotating rod (22) extending through the inside of the first fixing block (12). The sides of the three first rotating rods (22) close to the three first bevel gears (21) are fixedly connected to a second bevel gear (23). The three first rotating rods (22) are fixedly connected to a third bevel gear (24) on one side located inside the three first fixed columns (14); the tops of the three first fixed columns (14) are fixedly connected to a first waterproof box (25); the insides of the three first waterproof boxes (25) are rotatably connected to a second rotating rod (26) extending through the insides of the three first fixed columns (14); the bottoms of the three second rotating rods (26) are fixedly connected to a fourth bevel gear (27); the tops of the three second rotating rods (26) are fixedly connected to a fifth bevel gear (28); and the insides of the three first waterproof boxes (25) are rotatably connected to a sixth bevel gear (29) on one side close to the fifth bevel gear (28).

4. A sewage treatment equipment with an anti-clogging filter according to claim 3, characterized in that: The conveying unit comprises a second waterproof box (30) fixedly connected to the top of the material collecting trough (17); a seventh bevel gear (31) fixedly connected to the sixth bevel gear (29) is rotatably connected inside the second waterproof box (30); an eighth bevel gear (32) is rotatably connected to a side of the second waterproof box (30) close to the seventh bevel gear (31); a second rotating shaft (33) extending through the outside of the second waterproof box (30) and rotatably connected to the second waterproof box (30) is fixedly connected at the bottom of the eighth bevel gear (32); a spiral conveying blade (34) is fixedly connected to the second rotating shaft (33); and both the second rotating shaft (33) and the spiral conveying blade (34) are located inside the material collecting trough (17).

5. The sewage treatment equipment with an anti-clogging filter according to claim 1, characterized in that: A water inlet (6) is fixedly provided on the filter box (2), a water outlet (7) is fixedly provided on a side of the filter box (2) away from the water inlet (6), and a filter screen (10) is fixedly connected between the first fixing ring (8) and the second fixing ring (9).

6. The sewage treatment equipment with an anti-clogging filter according to claim 1, characterized in that: A scraping motor (35) is fixedly connected to the top of the sealing cover plate (3), and a driving end of the scraping motor (35) is fixedly connected to the first rotating shaft (11).

7. The sewage treatment equipment with an anti-clogging filter according to claim 1, characterized in that: The first gear (19) and the three second gears (20) are meshed with each other, the first bevel gear (21) and the second bevel gear (23) are meshed with each other, the third bevel gear (24) and the fourth bevel gear (27) are meshed with each other, the fifth bevel gear (28) and the sixth bevel gear (29) are meshed with each other, and the seventh bevel gear (31) and the eighth bevel gear (32) are meshed with each other.

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