High-purity lycium ruthenicum anthocyanin purification device

Abstract

The invention belongs to the technical field of anthocyanin purification, and particularly relates to a high-purity lycium ruthenicum anthocyanin purification device which comprises a purification cylinder, a crushing purification mechanism is arranged in the purification cylinder, the lower portion of the purification cylinder is communicated with a collection box through a connecting pipe, the collection box is communicated with an external negative pressure mechanism, and a blocking assembly is arranged in the collection box. The blocking assembly and the connecting pipe are correspondingly arranged up and down and are matched; the crushing and purifying mechanism comprises a crushing plate rotationally connected into the purifying barrel, the crushing plate is located in the middle of the purifying barrel and is coaxial with the purifying barrel, a first extrusion assembly and a second extrusion assembly which are used for extruding lycium ruthenicum are arranged on the two opposite sides of the crushing plate correspondingly, and the first extrusion assembly and the second extrusion assembly are coaxially and fixedly connected; the crushing plate is detachably connected with the first extrusion assembly and the second extrusion assembly, and a disturbance assembly is arranged on the crushing plate. The device can realize crushing, uniform mixing and separation of lycium ruthenicum, is simple in structure, and is convenient for efficiently completing anthocyanin purification operation of lycium ruthenicum.

Description

Technical Field

[0001] The invention belongs to the technical field of anthocyanin purification, and in particular relates to a high-purity black wolfberry anthocyanin purification device. Background Art

[0002] The anthocyanin content in black wolfberry is very high, several times that of ordinary food. It is known as the king of anthocyanins and is the most powerful free radical scavenger discovered so far. It is widely used in the prevention and treatment of cardiovascular and cerebrovascular diseases. It can inhibit free radicals in blood vessels and has anti-aging, antioxidant, and anti-atherosclerosis effects.

[0003] The traditional purification of anthocyanins from black wolfberry requires the separate operations of crushing, organic solution extraction, and separation and filtration. The raw materials are transferred multiple times between different equipment, which is not conducive to the simplification of production. The operation is time-consuming and labor-intensive, and the extraction efficiency and purity are low. Therefore, a high-purity black wolfberry anthocyanin purification device is urgently needed to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a high-purity black wolfberry anthocyanin purification device to solve the above problems.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A high-purity black wolfberry anthocyanin purification device, comprising: a purification cylinder, a crushing and purification mechanism is arranged in the purification cylinder, a collecting box is connected to the lower part of the purification cylinder through a connecting pipe, the collecting box is connected to an external negative pressure mechanism, a plugging component is arranged in the collecting box, and the plugging component is arranged correspondingly and matched with the connecting pipe above and below;

[0007] The crushing and purification mechanism includes a crushing plate rotatably connected to the purification cylinder, the crushing plate is located in the middle of the purification cylinder and is coaxially arranged with the purification cylinder, the first extrusion component and the second extrusion component for extruding black wolfberries are respectively arranged on opposite sides of the crushing plate, the first extrusion component and the second extrusion component are coaxially fixed, the crushing plate is detachably connected to the first extrusion component and the second extrusion component, and a disturbance component is arranged on the crushing plate.

[0008] Preferably, a plurality of crushing holes are provided on the crushing plate, the plurality of crushing holes are distributed in an array, slopes are circumferentially provided at the edges of the crushing holes, and a crushing net is fixedly connected in the crushing holes.

[0009] Preferably, the first extrusion assembly includes a first double-threaded shaft coaxially rotatably connected to the purification cylinder, one end of the first double-threaded shaft passes through the purification cylinder and is coaxially fixed to the output shaft of the driving motor through a coupling, a first push plate is slidably connected to the outer side of the first double-threaded shaft, a slider is rotatably connected at the inner edge of the first push plate, and the slider is slidably connected in the thread groove of the first double-threaded shaft.

[0010] Preferably, the second extrusion assembly comprises a second double-threaded shaft coaxially rotatably connected in the purification cylinder, a second push plate is slidably connected to the outer side of the second double-threaded shaft, a connecting ring is coaxially fixedly connected to one end of the second double-threaded shaft, the connecting ring is coaxially fixedly connected to the end of the first double-threaded shaft, a distance is left between the end of the first double-threaded shaft and the end of the second double-threaded shaft, and the crushing plate is coaxially rotatably connected to the connecting ring;

[0011] The connection structure between the second double-threaded shaft and the second push plate is the same as the connection structure between the first double-threaded shaft and the first push plate.

[0012] Preferably, two second slip rings are circumferentially fixedly connected to the outer edge of the connecting ring, the two second slip rings are coaxially arranged with the connecting ring, and the crushing plate is slidably connected between the two second slip rings;

[0013] A sliding groove is circumferentially provided at the outer edge of the crushing plate, and a first sliding ring is slidably connected in the sliding groove. The first sliding ring is circumferentially fixed to the inner wall of the purification cylinder, and there is friction between the first sliding ring and the sliding groove.

[0014] Preferably, a threaded hole is coaxially formed in the second double-threaded shaft, a threaded rod is threadedly connected in the threaded hole, one end of the threaded rod penetrates into the connecting ring, the end of the threaded rod that penetrates into the connecting ring is configured to be in a frustum shape, and a gap is left between the end of the threaded rod and the end of the first double-threaded shaft;

[0015] The connecting ring is provided with a through hole, a pin is slidably connected in the through hole, one end of the pin extends into the connecting ring and is fixedly connected with a magnetic block, and the magnetic block is magnetically connected to the end of the threaded rod;

[0016] A pin hole is provided at the inner edge of the crushing plate, and the pin hole is matched with the pin shaft.

[0017] Preferably, the disturbance component includes a scraper fixedly connected to the outer edge of the crushing plate, the scraper is arranged along the length direction of the purification cylinder, and a rubber strip is fixedly connected to the scraper, and the rubber strip is in sliding contact with the inner wall of the purification cylinder.

[0018] Preferably, a filter screen is fixedly connected to the top end of the connecting tube, and the filter screen is flush with the inner wall of the purification cylinder.

[0019] Preferably, the blocking assembly includes a telescopic rod fixedly connected to the bottom wall of the collection box, the telescopic end of the telescopic rod is fixedly connected to a baffle, the top surface of the baffle is in contact with the filter, and a plurality of reinforcing ribs are fixedly connected between the baffle and the telescopic end of the telescopic rod, and the plurality of reinforcing ribs are circumferentially evenly spaced.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] When the device of the present invention is used, firstly, cleaned black wolfberries and purified water are poured into the purification cylinder together, and the black wolfberries fall between the first extrusion component and the crushing plate. Then, the black wolfberries are continuously crushed by the crushing plate under the joint action of the first extrusion component and the second extrusion component. After a set time, an ethanol solution is put into the purification cylinder, and the mixed liquid is mixed by the disturbance component. After the mixing set time, the blocking component is opened and the external negative pressure mechanism is opened at the same time, and the mixed liquid is pumped into the collection box, and the solid residue is left in the purification cylinder.

[0022] The invention can realize the crushing, mixing and separation of black wolfberry and has a simple structure, thereby facilitating the efficient completion of the anthocyanin purification operation of the black wolfberry. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 for Figure 1 A partial enlarged view of the middle A;

[0026] Figure 3 for Figure 1 A partial enlarged view of point B in the middle;

[0027] Figure 4 It is a schematic diagram of the connection between the first double-threaded shaft and the first push plate in the present invention;

[0028] Figure 5 It is a front view of the slider in the present invention;

[0029] Among them, 1. driving motor; 2. purification cylinder; 3. sealing bearing; 4. first push plate; 5. feed port; 6. sealing plug; 7. sealing ring; 8. first double threaded shaft; 9. second double threaded shaft; 10. threaded rod; 11. second push plate; 12. knob; 13. collecting box; 14. telescopic rod; 15. guide block; 16. quick connector; 17. connecting pipe; 18. baffle; 19. filter; 20. reinforcing rib; 21. solenoid valve; 22. discharge pipe; 23. crushing plate; 24. slide; 25. first slip ring; 26. crushing hole; 27. crushing net; 28. second slip ring; 29. ​​connecting ring; 30. magnetic block; 31. pin shaft; 32. through hole; 33. pin hole; 34. slider; 35. scraper; 36. rubber strip. DETAILED DESCRIPTION

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

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Reference Figures 1 to 5 The present invention discloses a high-purity black wolfberry anthocyanin purification device, comprising: a purification cylinder 2, a crushing and purification mechanism is arranged in the purification cylinder 2, a collecting box 13 is connected to the lower part of the purification cylinder 2 through a connecting pipe 17, the collecting box 13 is connected to an external negative pressure mechanism, a blocking component is arranged in the collecting box 13, and the blocking component and the connecting pipe 17 are arranged correspondingly and matched with each other;

[0033] A guide block 15 is fixedly connected to the bottom of the collecting box 13. The top surface of the guide block 15 is inclined and the lower end faces the discharge port of the collecting box 13. A discharge pipe 22 is provided at the discharge port of the collecting box 13, and a solenoid valve 21 is provided on the discharge pipe 22.

[0034] A quick connector 16 is fixedly connected to and communicated with one side of the collection box 13, and the quick connector 16 is located at the upper part of the collection box 13;

[0035] The top of the purification cylinder 2 is fixedly connected to and communicated with a feed port 5 , a sealing plug 6 is detachably connected to the feed port 5 , a sealing ring 7 is circumferentially fixedly connected to the outer wall of the sealing plug 6 , and the sealing ring 7 is in sealing contact with the inner wall of the feed port 5 .

[0036] The crushing and purification mechanism includes a crushing plate 23 rotatably connected to the purification cylinder 2. The crushing plate 23 is located in the middle of the purification cylinder 2 and is coaxially arranged with the purification cylinder 2. The first extrusion component and the second extrusion component for extruding black wolfberries are respectively arranged on opposite sides of the crushing plate 23. The first extrusion component and the second extrusion component are coaxially fixed. The crushing plate 23 is detachably connected to the first extrusion component and the second extrusion component, and a disturbance component is arranged on the crushing plate 23.

[0037] When the device of the present invention is used, first, the cleaned black wolfberry and pure water are poured into the purification cylinder 2 together, and the black wolfberry falls between the first extrusion component and the crushing plate 23. Then, the black wolfberry is continuously crushed by the crushing plate 23 under the joint action of the first extrusion component and the second extrusion component. After a set time, an ethanol solution is added to the purification cylinder 2, and the mixed liquid is mixed by the disturbance component. After the mixing set time, the blocking component is opened and the external negative pressure mechanism is opened at the same time, and the mixed liquid is pumped into the collection box 13, and the solid residue remains in the purification cylinder 2.

[0038] According to a further optimized solution, a plurality of crushing holes 26 are provided on the crushing plate 23 , the plurality of crushing holes 26 are distributed in an array, slopes are provided circumferentially at the edges of the crushing holes 26 , and a crushing net 27 is fixedly connected in the crushing holes 26 .

[0039] Under the extrusion of the first extrusion assembly and the second extrusion assembly, the black wolfberry reciprocates through the crushing hole 26 and is cut and crushed by the crushing net 27 in the crushing hole 26. The function of the slope is to prevent the black wolfberry from being retained in the crushing hole 26 and affecting the crushing effect.

[0040] A further optimized solution is that the first extrusion assembly includes a first double-threaded shaft 8 which is coaxially rotatably connected in the purification cylinder 2, one end of the first double-threaded shaft 8 passes through the purification cylinder 2 and is coaxially fixed to the output shaft of the driving motor 1 through a coupling, and the outer side of the first double-threaded shaft 8 is slidably connected to the first push plate 4, and the inner edge of the first push plate 4 is rotatably connected to a slider 34, and the slider 34 is slidably connected in the thread groove of the first double-threaded shaft 8.

[0041] The first double-threaded shaft 8 is driven to rotate by the driving motor 1, and the first double-threaded shaft 8 drives the slider 34 to slide in the thread groove, thereby driving the first push plate 4 to reciprocate along the first double-threaded shaft 8, thereby achieving the extrusion of black wolfberries.

[0042] Further optimized solution, the second extrusion assembly includes a second double-threaded shaft 9 coaxially rotatably connected in the purification cylinder 2, the outer side of the second double-threaded shaft 9 is slidably connected with a second push plate 11, one end of the second double-threaded shaft 9 is coaxially fixed with a connecting ring 29, the connecting ring 29 is coaxially fixed with the end of the first double-threaded shaft 8, a distance is left between the end of the first double-threaded shaft 8 and the end of the second double-threaded shaft 9, and the crushing plate 23 is coaxially rotatably connected with the connecting ring 29;

[0043] The connection structure between the second double threaded shaft 9 and the second push plate 11 is the same as the connection structure between the first double threaded shaft 8 and the first push plate 4 .

[0044] The first double-threaded shaft 8 and the second double-threaded shaft 9 are both rotatably connected to the purification cylinder 2 via the sealed bearing 3 .

[0045] The second double threaded shaft 9 has the same structure as the first double threaded shaft 8. The second double threaded shaft 9 is driven by the first double threaded shaft 8. When the first push plate 4 approaches the crushing plate 23, the second push plate 11 moves away from the crushing plate 23. The first push plate 4 and the second push plate 11 move synchronously, thereby continuously squeezing and crushing the black wolfberry.

[0046] Further optimizing the scheme, two second slip rings 28 are fixedly connected to the outer edge of the connecting ring 29 in the circumferential direction, and the two second slip rings 28 are coaxially arranged with the connecting ring 29, and the crushing plate 23 is slidably connected between the two second slip rings 28;

[0047] A slide groove 24 is circumferentially provided at the outer edge of the crushing plate 23 , and a first slide ring 25 is slidably connected in the slide groove 24 . The first slide ring 25 is circumferentially fixed to the inner wall of the purification cylinder 2 , and there is friction between the first slide ring 25 and the slide groove 24 .

[0048] The provision of the first sliding ring 25 and the second sliding ring 28 can effectively prevent the crushing plate 23 from being deformed under the squeezing effect of the black wolfberry.

[0049] Further optimized, a threaded hole is coaxially opened in the second double-threaded shaft 9, a threaded rod 10 is threadedly connected in the threaded hole, one end of the threaded rod 10 is inserted into the connecting ring 29, and the end of the threaded rod 10 inserted into the connecting ring 29 is set to be a frustum, and a gap is left between the end of the threaded rod 10 and the end of the first double-threaded shaft 8;

[0050] A through hole 32 is formed on the connecting ring 29, and a pin shaft 31 is slidably connected in the through hole 32. One end of the pin shaft 31 extends into the connecting ring 29 and is fixedly connected to a magnetic block 30. The magnetic block 30 is magnetically connected to the end of the threaded rod 10.

[0051] A pin hole 33 is formed at the inner edge of the crushing plate 23 , and the pin hole 33 is matched with the pin shaft 31 .

[0052] A further optimized solution is that the disturbance component includes a scraper 35 fixedly connected to the outer edge of the crushing plate 23, the scraper 35 is arranged along the length direction of the purification cylinder 2, and a rubber strip 36 is fixedly connected to the scraper 35, and the rubber strip 36 is in sliding contact with the inner wall of the purification cylinder 2.

[0053] When the scraper 35 does not move, the scraper 35 acts as a guide rail, so that the first push plate 4 and the second push plate 11 can continuously reciprocate without rotating with the first double-threaded shaft 8 / the second double-threaded shaft 9;

[0054] When the scraper 35 moves, it disturbs the mixed liquid to facilitate mixing of the mixed liquid. At the same time, the residue on the filter screen 19 is scraped off by the rubber strip 36 to prevent the residue from affecting the filtration of the filter screen 19.

[0055] According to a further optimized solution, a filter screen 19 is fixedly connected to the top end of the connecting tube 17 , and the filter screen 19 is flush with the inner wall of the purification cylinder 2 .

[0056] A further optimized solution is that the blocking component includes a telescopic rod 14 fixedly connected to the bottom wall of the collecting box 13, the telescopic end of the telescopic rod 14 is fixedly connected to a baffle 18, the top surface of the baffle 18 is in contact with the filter screen 19, and a plurality of reinforcing ribs 20 are fixedly connected between the baffle 18 and the telescopic end of the telescopic rod 14, and the plurality of reinforcing ribs 20 are circumferentially evenly spaced.

[0057] The telescopic rod 14 extends, driving the baffle 18 to block the connecting pipe 17, thereby preventing the mixed liquid from falling into the collecting box 13 when the mixed liquid is not completely mixed. The reinforcing rib 20 can strengthen the connection strength between the telescopic rod 14 and the baffle 18.

[0058] When crushing, the pin shaft 31 is separated from the crushing plate 23, and is fixed by the friction between the rubber strip 36 and the inner wall of the purification cylinder 2 and the friction between the first sliding ring 25 and the slide groove 24. At this time, the first push plate 4 and the second push plate 11 both slide along the length direction of the scraper 35, and the first push plate 4 and the second push plate 11 both slide in contact with the inner wall of the purification cylinder 2, thereby crushing the black wolfberry;

[0059] During mixing, the threaded rod 10 is rotated by the knob 12 at the end of the threaded rod 10, and the threaded rod 10 pushes the pin shaft 31 into the pin hole 33. At this time, the first double threaded shaft 8 drives the crushing plate 23 to rotate, and then drives the scraper 35 to move in the purification cylinder 2 to stir the mixed liquid. After the stirring set time, the telescopic rod 14 descends and drives the baffle 18 to descend. The quick connector 16 on the collection box 13 is connected to the external negative pressure mechanism to keep the negative pressure in the collection box 13. The mixed liquid enters the collection box 13, and the residue remains in the purification cylinder 2 under the action of the filter 19. At the same time, the scraper 35 drives the rubber strip 36 to scrape away the residue above the filter 19 to prevent the residue from affecting the filtering efficiency of the filter 19.

[0060] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0061] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A high-purity black wolfberry anthocyanin purification device, characterized in that: include: A purification cylinder (2), wherein a crushing and purification mechanism is arranged in the purification cylinder (2), a collecting box (13) is connected to the bottom of the purification cylinder (2) through a connecting pipe (17), the collecting box (13) is connected to an external negative pressure mechanism, a plugging component is arranged in the collecting box (13), and the plugging component and the connecting pipe (17) are arranged correspondingly and matched with each other up and down; The crushing and purification mechanism comprises a crushing plate (23) rotatably connected to the purification cylinder (2); the crushing plate (23) is located in the middle of the purification cylinder (2) and is coaxially arranged with the purification cylinder (2); a first extrusion assembly and a second extrusion assembly for extruding black wolfberries are respectively arranged on opposite sides of the crushing plate (23); the first extrusion assembly and the second extrusion assembly are coaxially fixedly connected; the crushing plate (23) is detachably connected to the first extrusion assembly and the second extrusion assembly; and a disturbance assembly is arranged on the crushing plate (23).

2. A high-purity black wolfberry anthocyanin purification device according to claim 1, characterized in that: The crushing plate (23) is provided with a plurality of crushing holes (26), the plurality of crushing holes (26) are distributed in an array, a slope is provided in the circumferential direction at the edge of the crushing hole (26), and a crushing net (27) is fixedly connected in the crushing hole (26).

3. A high-purity black wolfberry anthocyanin purification device according to claim 1, characterized in that: The first extrusion assembly includes a first double-threaded shaft (8) coaxially rotatably connected to the purification cylinder (2), one end of the first double-threaded shaft (8) passes through the purification cylinder (2) and is coaxially fixed to the output shaft of the driving motor (1) through a coupling, the outer side of the first double-threaded shaft (8) is slidably connected to a first push plate (4), the inner edge of the first push plate (4) is rotatably connected to a slider (34), and the slider (34) is slidably connected in the thread groove of the first double-threaded shaft (8).

4. A high-purity black wolfberry anthocyanin purification device according to claim 3, characterized in that: The second extrusion assembly comprises a second double-threaded shaft (9) coaxially rotatably connected in the purification cylinder (2); a second push plate (11) is slidably connected to the outer side of the second double-threaded shaft (9); a connecting ring (29) is coaxially fixedly connected to one end of the second double-threaded shaft (9); the connecting ring (29) is coaxially fixedly connected to the end of the first double-threaded shaft (8); a distance is left between the end of the first double-threaded shaft (8) and the end of the second double-threaded shaft (9); and the crushing plate (23) is coaxially rotatably connected to the connecting ring (29); The connection structure between the second double-threaded shaft (9) and the second push plate (11) is the same as the connection structure between the first double-threaded shaft (8) and the first push plate (4).

5. A high-purity black wolfberry anthocyanin purification device according to claim 4, characterized in that: Two second slip rings (28) are fixedly connected to the outer edge of the connecting ring (29) in the circumferential direction. The two second slip rings (28) are coaxially arranged with the connecting ring (29). The crushing plate (23) is slidably connected between the two second slip rings (28). A sliding groove (24) is circumferentially provided at the outer edge of the crushing plate (23), and a first sliding ring (25) is slidably connected in the sliding groove (24). The first sliding ring (25) is circumferentially fixed to the inner wall of the purification cylinder (2), and there is friction between the first sliding ring (25) and the sliding groove (24).

6. A high-purity black wolfberry anthocyanin purification device according to claim 5, characterized in that: A threaded hole is coaxially formed inside the second double-threaded shaft (9), a threaded rod (10) is threadedly connected inside the threaded hole, one end of the threaded rod (10) is inserted into the connecting ring (29), the end of the threaded rod (10) inserted into the connecting ring (29) is configured to be a frustum, and a gap is left between the end of the threaded rod (10) and the end of the first double-threaded shaft (8); The connecting ring (29) is provided with a through hole (32), a pin shaft (31) is slidably connected in the through hole (32), one end of the pin shaft (31) extends into the connecting ring (29) and is fixedly connected with a magnetic attraction block (30), and the magnetic attraction block (30) is magnetically connected to the end of the threaded rod (10); A pin hole (33) is provided at the inner edge of the crushing plate (23), and the pin hole (33) is matched with the pin shaft (31).

7. A high-purity black wolfberry anthocyanin purification device according to claim 1, characterized in that: The disturbance component comprises a scraper (35) fixedly connected to the outer edge of the crushing plate (23), the scraper (35) being arranged along the length direction of the purification cylinder (2), and a rubber strip (36) being fixedly connected to the scraper (35), and the rubber strip (36) being in sliding contact with the inner wall of the purification cylinder (2).

8. A high-purity black wolfberry anthocyanin purification device according to claim 1, characterized in that: A filter screen (19) is fixedly connected to the top end of the connecting pipe (17), and the filter screen (19) is flush with the inner wall of the purification cylinder (2).

9. A high-purity black wolfberry anthocyanin purification device according to claim 8, characterized in that: The blocking assembly comprises a telescopic rod (14) fixedly connected to the bottom wall of the collection box (13); a baffle (18) is fixedly connected to the telescopic end of the telescopic rod (14); the top surface of the baffle (18) is in contact with the filter screen (19); a plurality of reinforcing ribs (20) are fixedly connected between the baffle (18) and the telescopic end of the telescopic rod (14); and the plurality of reinforcing ribs (20) are arranged at equal intervals in the circumferential direction.

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