CN220420855U - Combined shrinkage structure of plate-shaped antenna - Google Patents

Abstract

The utility model relates to the technical field of plate-shaped antennas, and discloses a combined contraction structure of a plate-shaped antenna, which comprises a main rod, wherein a fast-disassembly component capable of being clamped and connected and an adjustable adjusting component are arranged outside the main rod, the fast-disassembly component comprises a first fixed block arranged at the top of the main rod, the top of the first fixed block is provided with a clamping structure capable of being clamped and connected, the adjusting component comprises a first limiting plate arranged at the top of the main rod, the bottom of the first limiting plate is provided with a slidable sliding structure, the fast-disassembly component further comprises a fixed ring plate arranged at the bottom of the main rod, the outer wall of the fixed ring plate is provided with a hinged structure, the fast-disassembly component further comprises a first telescopic rod, the top of the first fixed block is fixedly provided with the first telescopic rod, the purpose of fast-disassembly of the device is achieved, the flexibility of the device is improved, workers can conveniently disassemble and repair parts which need to be overhauled according to overhauling requirements, the convenience of the device in use is improved, and overhauling pressure is lightened.

Description

Combined shrinkage structure of plate-shaped antenna

Technical Field

The utility model belongs to the technical field of plate-shaped antennas, and particularly relates to a combined shrinkage structure of a plate-shaped antenna.

Background

Is an important component in radio communication systems. An antenna is a device that can efficiently radiate electromagnetic waves in a specific direction in space or can efficiently receive electromagnetic waves in a specific direction in space, and has a certain directivity. Antennas can be classified into omni-directional antennas and directional antennas according to directivity.

The utility model discloses a dual-polarized plate-shaped antenna with the publication number of CN209561614U, which comprises a radiation antenna, a packaging shell arranged outside the radiation antenna and two fixed modules, wherein the same side wall of the packaging shell is respectively provided with a V-shaped rotating bracket and a rotating bracket, and one end of the V-shaped rotating bracket, which is far away from the packaging shell, is provided with a clamping part; the fixing module consists of a plurality of fixing monomers; the fixing units comprise arc plates, bolts and slots, the bolts and the slots are respectively arranged at two ends of the arc plates, the extending direction of the bolts is opposite to the opening direction of the slots, and the bolts and the slots of two adjacent fixing units are matched and fixed; the first two fixing monomers further comprise clamping bars, and the clamping bars are inserted into the clamping portions in a matched mode to be fixed. The utility model provides a dual-polarized plate-shaped antenna which can be adapted to the outer diameters of various rod bodies.

However, the above patent also has the following problems: the device is in the mounting process to platy antenna, can't directly dismantle platy antenna part, needs take off fixed knot constructs from the dead lever, does not set up quick detach structure on the device, and the device dismantles comparatively inconvenient, has increased workman's maintenance and installation pressure, and the device uses and has inconvenience, and the device is in the use, can't finely tune the position of antenna as required, and the receiving area of device can't be adjusted, and the device uses and experiences inadequately.

The present utility model has been made in view of this.

Disclosure of Invention

In order to solve the technical problems, the utility model adopts the basic conception of the technical scheme that:

the utility model provides a combination shrink structure of platy antenna, includes the mobile jib, but the outside of mobile jib is provided with quick detach subassembly and the adjustable regulation subassembly of joint, and quick detach subassembly is including setting up in the first fixed block at mobile jib top, but the top of first fixed block is provided with joint structure of joint, and regulation subassembly is including setting up in the first limiting plate at mobile jib top, and the bottom of first limiting plate is provided with slidable sliding structure, and quick detach subassembly is still including setting up in the fixed crown block of mobile jib bottom, but be provided with articulated hinge structure on the outer wall of fixed crown block.

As a preferred implementation mode of the utility model, the quick-release assembly further comprises a first telescopic rod, the top of the first fixed block is fixedly provided with the first telescopic rod, the top of the first telescopic rod is provided with a hole, the second telescopic rod is slidably arranged in the hole, the top of the second telescopic rod is fixedly provided with the second fixed block, the clamping structure comprises a spherical clamping groove, two groups of holes are formed in the outer wall of the first telescopic rod, a spherical clamping groove is fixedly arranged in the holes, the outer wall of the second telescopic rod is provided with a spherical clamping buckle, and the spherical clamping buckle can be clamped and installed in the two groups of spherical clamping grooves.

As a preferred implementation mode of the quick-release assembly, the quick-release assembly further comprises a first arc-shaped plate, the outer wall of the fixed ring plate is fixedly provided with the first arc-shaped plate, the hinge structure comprises hinge rods, two ends of the first arc-shaped plate are respectively provided with a group of hinge rods in a hinge mode, the outer wall of each hinge rod is fixedly provided with a second arc-shaped plate, the outer wall of each second arc-shaped plate is fixedly provided with connecting blocks, the number of the connecting blocks is two, one side outer wall of each connecting block is provided with two groups of holes, the holes are internally provided with internal thread grooves, the number of the internal thread grooves is four, one group of limit bolts are rotatably arranged between every two groups of internal thread grooves, and the two groups of limit bolts are altogether.

As a preferred implementation mode of the utility model, the quick-release assembly further comprises soft cushions, a group of soft cushions are stuck and installed on the inner walls of the two groups of second arc plates and the inner wall of the first arc plate, a group of auxiliary blocks are fixedly installed on the outer walls of the first fixing block and the second fixing block, a hole is formed in the outer wall of one side of the auxiliary block, a buckling groove is fixedly installed in the hole, two groups of buckling blocks are arranged outside the main rod, and the buckling blocks can be installed inside the buckling groove in a clamping mode.

As a preferred embodiment of the utility model, the adjusting component further comprises a second limiting plate, the top of the main rod is provided with the second limiting plate, the second limiting plate is positioned below the first limiting plate, the sliding structure comprises limiting groove holes, a group of groove holes are formed in the bottom of the first limiting plate and the top of the second limiting plate, limiting groove holes are fixedly arranged in the groove holes, a group of bar-shaped groove holes are formed in the inner walls of two sides of the limiting groove holes, limiting sliding rails are fixedly arranged in the bar-shaped groove holes, and the four groups of limiting sliding rails are arranged in the bar-shaped groove holes.

As a preferred implementation mode of the utility model, the adjusting component further comprises limit sliding blocks, four groups of limit sliding blocks are slidably arranged in each group of limit sliding rails, twelve groups of limit sliding blocks are arranged in each group of limit groove holes, four groups of first support plates are fixedly arranged in each group of limit groove holes, one group of second support plates are fixedly arranged between every two groups of first support plates, four groups of second support plates are arranged, one group of third support plates are fixedly arranged between every two groups of second support plates, and two groups of third support plates are arranged.

As a preferred embodiment of the utility model, the adjusting component further comprises arc-shaped fixing plates, six groups of arc-shaped fixing plates are fixedly arranged on the outer walls of two sides of the third support plate, one group of first fixing rods are fixedly arranged between every two groups of arc-shaped fixing plates, two groups of second fixing rods are fixedly arranged on the outer wall of each first fixing rod, twenty four groups of second fixing rods are totally arranged on the outer wall of each second fixing rod, a fourth support plate is fixedly arranged on the outer wall of one side of each second fixing rod, a spherical hinge groove is fixedly arranged on the outer wall of one side of each fourth support plate, a spherical hinge part is hinged in each spherical hinge groove, one end of each spherical hinge part is fixedly provided with a third fixing rod, and the top of each third fixing rod is fixedly provided with a plate-shaped antenna.

As a preferred embodiment of the utility model, the data connecting wire is fixedly arranged on the outer wall of one side of the first limiting plate, the hole is formed on the outer wall of one side of the second fixing block, the clamping interface is fixedly arranged in the hole, one end of the data connecting wire can be clamped and arranged in the clamping interface, a hole is formed at the bottom of the main rod, an electric wire is fixedly arranged in the hole, and the outer wall of one side of the clamping block is fixedly connected with the outer walls of one sides of the first limiting plate and the second limiting plate.

Compared with the prior art, the utility model has the following beneficial effects:

1. the device is quickly disassembled, the flexibility of the device is improved, workers can conveniently install the device, the part to be overhauled is disassembled and repaired according to overhauling requirements, the use convenience of the device is improved, and overhauling pressure is reduced.

2. The purpose of adjusting the position of the device is achieved, the position of the plate-shaped antenna is adjusted according to the requirement, the transceiving effect of the device is improved, the signal transceiving intensity of the device is improved, the use stability of the device is improved, and the use experience of the device is optimized.

3. The stability of device use is improved, the stability of device signal receiving and transmitting is improved, the information received by the antenna is transmitted, the service life of the device is prolonged, and the service life of the device is prolonged.

The following describes the embodiments of the present utility model in further detail with reference to the accompanying drawings.

Drawings

In the drawings:

FIG. 1 is a front view of the present utility model;

FIG. 2 is a bottom perspective view of FIG. 1 of the present utility model;

FIG. 3 is a bottom perspective view of the present utility model in FIG. 2;

FIG. 4 is a right side perspective view of the present utility model;

FIG. 5 is a perspective view of the structure of the present utility model in FIG. 1;

FIG. 6 is a perspective view of the structure of the present utility model in FIG. 2;

fig. 7 is a perspective view of the structure of the present utility model in fig. 3.

In the figure: 10. a main rod; 11. a first fixed block; 12. a first telescopic rod; 13. a second telescopic rod; 14. a second fixed block; 15. spherical buckling grooves; 16. spherical buckle; 17. an electric wire; 18. a fixed ring plate; 19. a first arcuate plate; 20. a hinge rod; 21. a second arcuate plate; 22. a connecting block; 23. an internal thread groove; 24. a limit bolt; 25. a soft cushion; 26. an auxiliary block; 27. a first limiting plate; 28. a second limiting plate; 29. a buckle block; 30. a buckle groove; 31. limiting groove holes; 32. a limit sliding rail; 33. a limit sliding block; 34. a first support plate; 35. a second support plate; 36. a third support plate; 37. an arc-shaped fixing plate; 38. a first fixing rod; 39. a second fixing rod; 40. a fourth support plate; 41. spherical hinge grooves; 42. a spherical hinge; 43. a third fixing rod; 44. a plate-like antenna; 45. and a data link line.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and the following embodiments are used to illustrate the present utility model.

Embodiment one: the utility model provides a combination shrink structure of platy antenna, specifically is shown as shown in fig. 1, including mobile jib 10, the outside of mobile jib 10 is provided with but quick detach subassembly and adjustable regulation subassembly of joint, and quick detach subassembly is provided with but the joint structure of joint including setting up in the first fixed block 11 at mobile jib 10 top, the top of first fixed block 11, and regulation subassembly is including setting up in the first limiting plate 27 at mobile jib 10 top, and the bottom of first limiting plate 27 is provided with slidable sliding structure, and quick detach subassembly is still including setting up in the fixed ring board 18 of mobile jib 10 bottom, is provided with but articulated hinge structure on the outer wall of fixed ring board 18. The device is quickly assembled and disassembled through the quick-dismantling assembly, and the position of the plate-shaped antenna is adjusted through the adjusting assembly.

Specifically as shown in fig. 1, the quick-release assembly further comprises a first telescopic rod 12, the top of the first fixed block 11 is fixedly provided with the first telescopic rod 12, the top of the first telescopic rod 12 is provided with a hole, the second telescopic rod 13 is slidably mounted in the hole, the top of the second telescopic rod 13 is fixedly provided with a second fixed block 14, the clamping structure comprises a spherical clamping groove 15, two groups of holes are formed in the outer wall of the first telescopic rod 12, a spherical clamping groove 15 is fixedly mounted in each hole, a spherical clamping 16 is arranged on the outer wall of the second telescopic rod 13, and the spherical clamping 16 can be clamped and mounted in the two groups of spherical clamping grooves 15. The second fixing block 14 is pushed to drive the second telescopic rod 13 to move in the first telescopic rod 12, so that the spherical buckle groove 15 is clamped and installed in the spherical buckle 16.

Specifically as shown in fig. 2 and 6, the quick detach subassembly still includes first arc 19, fixed mounting has first arc 19 on the outer wall of fixed ring board 18, the hinge structure includes articulated pole 20, a set of articulated pole 20 is all articulated to the both ends of first arc 19, fixed mounting has second arc 21 on the outer wall of articulated pole 20, fixed mounting has connecting block 22 on the outer wall of second arc 21, the quantity of connecting block 22 is two sets of, two sets of holes have all been seted up on the outer wall of one side of two sets of connecting blocks 22, be provided with internal thread groove 23 in the hole, the quantity of internal thread groove 23 is four sets of, rotate between every two sets of internal thread groove 23 and install a set of limit bolt 24, two sets of limit bolts 24 altogether. The second arc-shaped plate 21 is shifted to drive the hinging rod 20 to hinge and rotate on the first arc-shaped plate 19, the second arc-shaped plate 21 is sleeved and arranged on the outer wall of the fixed column, the limiting bolt 24 is spirally arranged in the internal thread groove 23 through the rotation of the limiting bolt 24, two groups of connecting blocks 22 are tightly attached and fixed, and the soft cushion 25 is tightly attached and fixed with the fixing.

As shown in fig. 5, the quick-release assembly further includes a cushion 25, a set of cushions 25 are adhered and mounted on the inner walls of the two sets of second arc plates 21 and the inner wall of the first arc plate 19, a set of auxiliary blocks 26 are fixedly mounted on the outer walls of the first fixing block 11 and the second fixing block 14, an opening is formed in one side outer wall of the auxiliary block 26, a fastening groove 30 is fixedly mounted in the opening, two sets of fastening blocks 29 are arranged on the outer portion of the main rod 10, and the fastening blocks 29 can be fastened and mounted in the fastening groove 30. The fastening block 29 is fastened and mounted in the fastening groove 30, so that the first limiting plate 27 and the second limiting plate 28 are tightly attached to the auxiliary block 26.

According to the above, the purpose of quick disassembly of the device is achieved through the structures of the first fixing block 11, the first telescopic rod 12, the second telescopic rod 13, the second fixing block 14, the spherical buckling groove 15, the spherical buckling 16, the electric wire 17, the fixing ring plate 18, the first arc plate 19, the hinging rod 20, the second arc plate 21, the connecting block 22, the internal thread groove 23, the limit bolt 24, the soft cushion 25, the auxiliary block 26, the first limit plate 27, the second limit plate 28, the buckling block 29 and the buckling groove 30, the flexibility of the device is improved, the device is convenient to install by workers, the part needing to be overhauled is disassembled and repaired according to overhauling requirements, the convenience of the device use is improved, and overhauling pressure is lightened.

Embodiment two: on the basis of the first embodiment, as shown in fig. 2, 3 and 4, the adjusting component further comprises a second limiting plate 28, the top of the main rod 10 is provided with the second limiting plate 28, the second limiting plate 28 is located below the first limiting plate 27, the sliding structure comprises a limiting groove hole 31, a group of groove holes are formed in the bottom of the first limiting plate 27 and the top of the second limiting plate 28, limiting groove holes 31 are fixedly mounted in the groove holes, a group of bar-shaped groove holes are formed in the inner walls of two sides of the limiting groove holes 31, limiting slide rails 32 are fixedly mounted in the bar-shaped groove holes, and four groups of limiting slide rails 32 are formed.

As shown in fig. 3 and fig. 4, the adjusting assembly further includes a limiting slider 33, four groups of limiting sliders 33 are slidably mounted in each group of limiting slider 32, twelve groups of limiting sliders 33 are provided in each group of limiting slot holes 31, four groups of first support plates 34 are fixedly mounted in each group of limiting sliders 33, a group of second support plates 35 are fixedly mounted between each two groups of first support plates 34, four groups of second support plates 35 are provided in total, a group of third support plates 36 are fixedly mounted between each two groups of second support plates 35, and two groups of third support plates 36 are provided in total. The third support plate 36 is shifted to drive the second support plate 35 to move, so that the limit sliding block 33 and the first support plate 34 are driven to slide in the limit sliding rail 32, and the position of the third support plate 36 is adjusted.

As shown in fig. 4 and 7, the adjusting assembly further includes an arc fixing plate 37, six groups of arc fixing plates 37 are fixedly installed on outer walls of two sides of the third support plate 36, a group of first fixing rods 38 are fixedly installed between every two groups of arc fixing plates 37, two groups of second fixing rods 39 are fixedly installed on outer walls of the first fixing rods 38, twenty four groups of second fixing rods 39 are totally installed on outer walls of one side of the second fixing rods 39, a fourth support plate 40 is fixedly installed on outer walls of one side of the fourth support plate 40, a spherical hinge groove 41 is fixedly installed on an outer wall of one side of the fourth support plate 40, a spherical hinge piece 42 is installed in the spherical hinge groove 41 in a hinged mode, a third fixing rod 43 is fixedly installed at one end of the spherical hinge piece 42, and a plate-shaped antenna 44 is fixedly installed at the top of the third fixing rod 43. And 4, stirring the rod 4, driving the spherical hinge piece 42 and the third fixing rod 43 to hinge in the spherical hinge groove 41, changing the orientation of the plate-shaped antenna 44, and limiting and fixing the position of the second fixing rod 39 through the arc-shaped fixing plate 37 and the first fixing rod 38.

According to the above, the purpose of adjusting the device position is achieved through the structures of the limiting groove hole 31, the limiting sliding rail 32, the limiting sliding block 33, the first supporting plate 34, the second supporting plate 35, the third supporting plate 36, the arc-shaped fixing plate 37, the first fixing rod 38, the second fixing rod 39, the fourth supporting plate 40, the spherical hinge groove 41, the spherical hinge piece 42, the third fixing rod 43 and the plate-shaped antenna 44, the position of the plate-shaped antenna is adjusted according to the requirement, the transceiving effect of the device is improved, the signal transceiving intensity of the device is improved, the use stability of the device is improved, and the use experience of the device is optimized.

Embodiment III: on the basis of the first embodiment and the second embodiment, as shown in fig. 1 and fig. 5, a data connection line 45 is fixedly installed on one side outer wall of the first limiting plate 27, a hole is formed on one side outer wall of the second fixing block 14, a clamping interface is fixedly installed in the hole, one end of the data connection line 45 can be clamped and installed in the clamping interface, a hole is formed in the bottom of the main rod 10, an electric wire 17 is fixedly installed in the hole, and one side outer wall of the clamping block 29 is fixedly connected with one side outer walls of the first limiting plate 27 and the second limiting plate 28. The antenna is connected to the device via a data connection 45 and the device is supplied via an electrical line 17.

In summary, through the structures of the electric wire 17, the first limiting plate 27, the second limiting plate 28, the fastening block 29 and the data connecting wire 45, the stability of the device in use is improved, the stability of signal receiving and transmitting of the device is improved, the information received by the antenna is transmitted, the service life of the device is prolonged, and the service life of the device is prolonged.

It will be understood that the utility model has been described in terms of several embodiments, and that various changes and equivalents may be made to these features and embodiments by those skilled in the art without departing from the spirit and scope of the utility model. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the utility model without departing from the essential scope thereof. Therefore, it is intended that the utility model not be limited to the particular embodiment disclosed, but that the utility model will include all embodiments falling within the scope of the appended claims.

Claims (8)

1. The utility model provides a combination shrink structure of platy antenna, includes mobile jib (10), its characterized in that, the outside of mobile jib (10) is provided with quick detach subassembly and adjustable regulation subassembly of joint, and quick detach subassembly is provided with joint structure including setting up in first fixed block (11) at mobile jib (10) top, first fixed block (11) at the top of being provided with joint, regulation subassembly is provided with slidable sliding structure including setting up in first limiting plate (27) at mobile jib (10) top, the bottom of first limiting plate (27) still including setting up fixed ring board (18) in mobile jib (10) bottom, is provided with articulated hinge structure on the outer wall of fixed ring board (18).

2. The plate-shaped antenna combined shrinkage structure according to claim 1, wherein the quick-release assembly further comprises a first telescopic rod (12), the first telescopic rod (12) is fixedly arranged at the top of the first fixed block (11), a hole is formed in the top of the first telescopic rod (12), the second telescopic rod (13) is slidably arranged in the hole, the second fixed block (14) is fixedly arranged at the top of the second telescopic rod (13), the clamping structure comprises a spherical clamping groove (15), two groups of holes are formed in the outer wall of the first telescopic rod (12), spherical clamping grooves (15) are fixedly arranged in the holes, spherical clamping buckles (16) are arranged on the outer wall of the second telescopic rod (13), and the spherical clamping buckles (16) can be clamped and installed inside the two groups of spherical clamping grooves (15).

3. The plate antenna combination shrinkage structure according to claim 2, wherein the quick-release assembly further comprises a first arc plate (19), the first arc plate (19) is fixedly installed on the outer wall of the fixed ring plate (18), the hinge structure comprises hinge rods (20), a group of hinge rods (20) are hinged at two ends of the first arc plate (19), a second arc plate (21) is fixedly installed on the outer wall of the hinge rod (20), connecting blocks (22) are fixedly installed on the outer wall of the second arc plate (21), the number of the connecting blocks (22) is two, two groups of holes are formed in the outer wall of one side of each connecting block (22), internal thread grooves (23) are formed in the holes, a group of limit bolts (24) are rotatably installed between every two groups of internal thread grooves (23), and the total number of the limit bolts (24) is two groups.

4. A combination shrinkage structure of a plate antenna according to claim 3, wherein the quick-release assembly further comprises soft cushions (25), a group of soft cushions (25) are adhered and mounted on the inner walls of the two groups of second arc plates (21) and the inner wall of the first arc plate (19), a group of auxiliary blocks (26) are fixedly mounted on the outer walls of the first fixing block (11) and the second fixing block (14), a hole is formed in one side outer wall of the auxiliary block (26), a buckling groove (30) is fixedly mounted in the hole, two groups of buckling blocks (29) are arranged on the outer portion of the main rod (10), and the buckling blocks (29) can be clamped and mounted in the buckling groove (30).

5. The plate-shaped antenna combined shrinkage structure according to claim 1, wherein the adjusting component further comprises a second limiting plate (28), the top of the main rod (10) is provided with the second limiting plate (28), the second limiting plate (28) is located below the first limiting plate (27), the sliding structure comprises a limiting groove hole (31), a group of groove holes are formed in the bottom of the first limiting plate (27) and the top of the second limiting plate (28), limiting groove holes (31) are fixedly installed in the groove holes, a group of bar-shaped groove holes are formed in the inner walls of two sides of the limiting groove holes (31), limiting sliding rails (32) are fixedly installed in the bar-shaped groove holes, and the four groups of limiting sliding rails (32) are formed in the bar-shaped groove holes.

6. The plate-shaped antenna combined contraction structure according to claim 5, wherein the adjusting assembly further comprises limit sliding blocks (33), four groups of limit sliding blocks (33) are slidably mounted in each group of limit sliding rails (32), twelve groups of limit sliding blocks (33) are formed in each group of limit slot holes (31), four groups of first supporting plates (34) are fixedly mounted in each group of the first supporting plates (34), one group of limit sliding blocks (33) are fixedly mounted between each two groups of the first supporting plates (34), one group of second supporting plates (35) are fixedly mounted between each two groups of the first supporting plates (34), one group of third supporting plates (36) are fixedly mounted between each two groups of the second supporting plates (35), and two groups of the third supporting plates (36) are formed.

7. The plate antenna combined contraction structure according to claim 6, wherein the adjusting component further comprises arc-shaped fixing plates (37), six groups of arc-shaped fixing plates (37) are fixedly installed on outer walls of two sides of the third support plate (36), one group of first fixing rods (38) are fixedly installed between every two groups of arc-shaped fixing plates (37), two groups of second fixing rods (39) are fixedly installed on outer walls of the first fixing rods (38), twenty-four groups of second fixing rods (39) are altogether, a fourth support plate (40) is fixedly installed on one outer wall of the second fixing rods (39), a spherical hinge groove (41) is fixedly installed on one outer wall of the fourth support plate (40), spherical hinge pieces (42) are fixedly installed in the spherical hinge grooves (41), one end of each spherical hinge piece (42) is fixedly installed with a third fixing rod (43), and the top of each third fixing rod (43) is fixedly installed with the plate antenna (44).

8. The plate-shaped antenna combined shrinkage structure according to claim 1, wherein a data connection line (45) is fixedly installed on one side outer wall of the first limiting plate (27), a hole is formed in one side outer wall of the second fixing block (14), a clamping interface is fixedly installed in the hole, one end of the data connection line (45) can be clamped and installed in the clamping interface, a hole is formed in the bottom of the main rod (10), an electric wire (17) is fixedly installed in the hole, and one side outer wall of the clamping block (29) is fixedly connected with one side outer walls of the first limiting plate (27) and the second limiting plate (28).