A flame retardant volute variable frequency centrifugal fan

Abstract

The utility model discloses a flame retardant volute variable frequency centrifugal fan, which relates to the technical field of fans. The flame retardant volute variable frequency centrifugal fan comprises a guide component, which is used to guide wind; a drive component, which is arranged in the inner cavity of the guide component, and the drive component is used to drive the wind to move; and a mounting component, which is arranged on the bottom surface of the guide component, and the mounting component is used to provide support for the guide component. The mounting component comprises a mounting plate, and fixing holes are provided at the four corners of the top surface of the mounting plate. The utility model can compress and transport gas, and is convenient for staff to disassemble and repair, and can be convenient for staff to conduct regular inspections, so as to increase the service life, and has good flame retardant effect, and can suppress the speed of flame spread.

Description

Technical Field

[0001] The utility model relates to the technical field of fans, in particular to a flame-retardant volute variable frequency centrifugal fan. Background Art

[0002] A fan is a machine that relies on input mechanical energy to increase gas pressure and discharge gas. It is a driven fluid machine. In China, fan is the customary abbreviation for gas compression and gas delivery machinery, usually including ventilators, blowers, wind turbines and other types. The working principle of a fan is mainly to promote air flow through the rotation of the blades on the wind wheel, thereby realizing functions such as transportation, ventilation, and air conditioning. Fans are widely used in many fields, such as ventilation, dust removal and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings, ventilation and air intake of boilers and industrial furnaces, cooling and ventilation in air conditioning equipment and household appliances, drying and selection of grains, wind tunnel wind sources and inflation and propulsion of hovercraft, etc. In addition, fans are also used in the field of transportation, such as the engine cooling system of vehicles and ships. In the field of construction, fans play an important role in ventilation, exhaust and air supply, which helps to keep indoor air fresh and clean and improve the comfort of the indoor environment.

[0003] Although the existing flame-retardant volute variable frequency centrifugal fan can guide the gas, it is inconvenient to repair it, which shortens its service life and reduces its work efficiency. Therefore, we propose a flame-retardant volute variable frequency centrifugal fan to solve the above problems. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a flame-retardant volute variable frequency centrifugal fan, which solves the problem of inconvenient maintenance thereof.

[0005] To achieve the above objectives, the utility model is implemented through the following technical solutions: A flame-retardant volute variable frequency centrifugal fan, comprising a guide component, the guide component is used to guide the wind;

[0006] A driving assembly, the driving assembly being disposed in the inner cavity of the guide assembly and being used to drive the wind to move; and

[0007] The mounting assembly is arranged on the bottom surface of the guide assembly, and the mounting assembly is used to provide support for the guide assembly.

[0008] Preferably, the mounting assembly includes a mounting plate, fixing holes are provided at the four corners of the top surface of the mounting plate, support columns are provided on the top surface of the mounting plate and near the four fixing holes, and two arc-shaped plates are provided on the top surfaces of the four support columns.

[0009] Preferably, a reinforcing plate is provided between both sides of the two side walls of the two arc-shaped plates, and the reinforcing plate is used to increase the strength of the arc-shaped plates.

[0010] Preferably, the guide assembly includes a volute, the volute is arranged in the inner cavity of the arc-shaped plate, a volute cover is arranged on one side surface of the volute, the volute cover is connected to the one side surface of the volute through a first fixing bolt, a mounting hole is opened on one side surface of the volute cover near the center position, four mounting holes are opened, the four mounting holes are distributed in a rectangular array, and the inner cavity of the mounting hole is connected to the driving assembly;

[0011] A flange is provided at the open end of one side of the volute, and the flange is connected to the volute and the volute cover through a second fixing bolt, and connection holes are provided at the four corners of the surface of one side of the flange;

[0012] The other side surface of the volute and the inner cavity surface of the volute are both provided with a clamping ring, and the outer side of the clamping ring is connected to the driving component.

[0013] Preferably, an inlet is opened at the center of the other side surface of the volute, a limit plate is arranged outside the inlet, the limit plate is connected to the other side surface of the volute through a locking bolt, and a filter is arranged in the inner cavity of the limit plate.

[0014] Preferably, the driving assembly includes a connecting plate, which is arranged on one side surface of the volute cover, and four limiting bolts are arranged on one side surface of the connecting plate, and the bottom ends of the four limiting bolts are connected to the inner cavity of the mounting hole, and a variable frequency motor is arranged at the center position of one side surface of the connecting plate, and a wheel disc is arranged at the output end of the variable frequency motor, and the wheel disc is connected to the output end of the variable frequency motor through a locking bolt, and blades are arranged between the wheel discs, and a plurality of blades are arranged, and the plurality of blades are distributed in a circular array.

[0015] Preferably, engaging grooves are provided on both side surfaces of the wheel disc, and the inner cavity of the engaging grooves is connected to the engaging ring. Beneficial Effects

[0016] The utility model provides a flame-retardant volute variable frequency centrifugal fan. Compared with the prior art, it has the following beneficial effects:

[0017] When the flame retardant volute variable frequency centrifugal fan needs to be installed, the installation component is first fixedly connected at a preset position, and then the guide component is fixedly connected to the top of the installation component, so that the installation component can provide support for the guide component, and then the guide component can guide, so as to effectively guide the airflow. Since the driving component is fixedly installed in the inner cavity of the guide component, the guide component can provide support for the driving component, so that it is convenient for the staff to install and disassemble the driving component, so that it is convenient for the staff to carry out maintenance and increase the service life. Then, through the driving component, the gas can be compressed and transported, so as to promote air circulation, so as to help improve the air transparency in the closed environment and optimize the working environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0019] Figure 2 It is a schematic diagram of the overall side structure of the utility model;

[0020] Figure 3 This is a schematic diagram of the installation assembly structure of the utility model;

[0021] Figure 4 This is a schematic diagram of the structure of the guide assembly of the utility model;

[0022] Figure 5 This is a schematic diagram of the planing structure of the guide assembly of the utility model;

[0023] Figure 6 This is a schematic diagram of the structure of the drive assembly of the utility model;

[0024] Figure 7 This is a schematic diagram of the planing structure of the drive assembly of the utility model.

[0025] In the figure: 1. Installation assembly; 11. Installation plate; 12. Fixing hole; 13. Support column; 14. Arc plate; 15. Reinforcement plate; 2. Guide assembly; 21. Volute; 22. Volute cover; 23. First fixing bolt; 24. Installation hole; 25. Inlet; 26. Limit plate; 27. Locking bolt; 28. Filter; 29. ​​Flange; 210. Second fixing bolt; 211. Connection hole; 212. Clamping ring; 3. Drive assembly; 31. Connection plate; 32. Limiting bolt; 33. Frequency conversion motor; 34. Wheel; 35. Clamping bolt; 36. Blade; 37. Clamping groove. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] See also Figure 1-7 The utility model provides a technical solution: a flame-retardant volute variable frequency centrifugal fan, comprising a guide assembly 2, the guide assembly 2 is used to guide the wind; a drive assembly 3, the drive assembly 3 is arranged in the inner cavity of the guide assembly 2, the drive assembly 3 is used to drive the wind to move; and a mounting assembly 1, the mounting assembly 1 is arranged on the bottom surface of the guide assembly 2, and the mounting assembly 1 is used to provide support for the guide assembly 2;

[0028] When it is necessary to install the flame-retardant volute variable frequency centrifugal fan, first fix the installation component 1 at a preset position, and then fix the guide component 2 at the top of the installation component 1, so that the installation component 1 can provide support for the guide component 2, and then the guide component 2 can be guided, so as to effectively guide the airflow. Since the driving component 3 is fixedly installed in the inner cavity of the guide component 2, the guide component 2 can provide support for the driving component 3, so that the staff can install and disassemble the driving component 3 conveniently, so that the staff can conveniently carry out maintenance and improve the service life. Then, through the driving component 3, the gas can be compressed and transported, so as to promote air circulation, so as to help improve the air transparency in the closed environment and optimize the working environment.

[0029] See also Figure 1 , Figure 2 , Figure 3 The mounting assembly 1 includes a mounting plate 11, and fixing holes 12 are provided at four corners of the top surface of the mounting plate 11. Support columns 13 are provided on the top surface of the mounting plate 11 and near the four fixing holes 12. Two arc-shaped plates 14 are provided on the top surfaces of the four support columns 13. Reinforcing plates 15 are provided between the two sides of the two side walls of the two arc-shaped plates 14. The reinforcing plates 15 are used to increase the strength of the arc-shaped plates 14.

[0030] The mounting plate 11 in the mounting assembly 1 can be fixedly connected at a preset position and can provide a space for the fixing hole 12. Since the fixing hole 12 is elliptical, the staff can connect it to external equipment through the fixing hole, and then the position of the mounting plate 11 can be easily adjusted to improve convenience. Since the top surface of the mounting plate 11 and the positions close to the four fixing holes 12 are fixedly connected with support columns 13, and the top surfaces of the four support columns 13 are fixedly connected with two arc plates 14, and at the same time, reinforcing plates 15 are fixedly connected between the two side walls of the two arc plates 14, the support columns 13 can provide support for the arc plates 14, and then the reinforcing plates 15 can increase the strength of the arc plates 14, so as to provide stable support for the guide assembly 2.

[0031] See also Figure 1 , Figure 2 , Figure 4 , Figure 5 The guide assembly 2 includes a volute 21, which is arranged in the inner cavity of the arc plate 14. A volute cover 22 is arranged on one side of the volute 21. The volute cover 22 is connected to the surface of one side of the volute 21 through a first fixing bolt 23. A mounting hole 24 is opened near the center of the surface of one side of the volute cover 22. There are four mounting holes 24, which are distributed in a rectangular array. The inner cavity of the mounting hole 24 is connected to the driving assembly 3; a flange 29 is arranged at an open end of one side of the volute 21, and the flange 29 is fixed by a second fixing bolt. 210 is connected to the volute 21 and the volute cover 22, and connecting holes 211 are provided at the four corners of one side surface of the flange 29; the other side surface of the volute 21 and the inner surface of the volute 21 are provided with a clamping ring 212, and the outer side of the clamping ring 212 is connected to the driving component 3, and the other side surface of the volute 21 is provided with an inlet 25 at the center position, and a limit plate 26 is provided on the outer side of the inlet 25, and the limit plate 26 is connected to the other side surface of the volute 21 through a locking bolt 27, and a filter screen 28 is provided in the inner cavity of the limit plate 26;

[0032] The volute 21 in the guide assembly 2 can be fixedly connected to the inner cavity of the arc plate 14 and can provide an installation foundation for the volute cover 22. Since the volute cover 22 is connected to the surface of one side of the volute cover 21 through the first fixing bolt 23, the volute cover 22 and the volute cover 21 can form a whole, so that the volute cover 22 and the volute cover 21 can guide the gas, so that it is convenient for the staff to disassemble and install the volute cover 22 and to inspect the interior. Since the volute cover 22 and the volute case 21 are composite materials formed by mineral fibers and resins, and the composite materials have the advantages of high strength and high temperature resistance, the mineral fibers can provide the skeleton and reinforcement of the composite materials, so as to facilitate the maintenance of the internal parts. The resin can fill the gaps between the fibers and firmly bond the fibers together to form an integral structure. This structure enables the composite material to effectively disperse and transfer stress through the joint action of the fibers and the resin when subjected to external force, thereby improving the strength and toughness of the material. The mineral fibers and the resin themselves have good flame retardant and high temperature resistance, and can effectively resist the erosion and spread of flames. Since a mounting hole 24 is provided on one side surface of the volute cover 22 near the center, and the inner cavity of the mounting hole 24 is connected to the drive assembly 3, the drive assembly 3 can be fixedly installed in the center of one side surface of the volute cover 22 through the mounting hole 24, thereby being able to The driving component 3 can drive the gas to be transported so as to facilitate ventilation. A flange 29 is installed at the open end of one side of the volute 21, and the flange 29 is connected to the volute 21 and the volute cover 22 through a second fixing bolt 210. At the same time, connecting holes 211 are opened at the four corners of the surface of one side of the flange 29, so that the flange 29 can be fixedly connected to the open end of the volute 21 through the second fixing bolt 210, and then can be connected to an external device through the connecting hole 211, so as to facilitate the gas transportation. A clamping ring 212 is fixedly connected to the other side surface of the volute 21 and the inner cavity surface of the volute 21, and the outer side of the clamping ring 212 is connected to the driving component 3. Thereby, the locking ring 212 can guide the output end of the drive component 3, thereby improving the stability of the rotation of the output end of the drive component 3, so as to improve safety. Since an inlet port 25 is opened in the center position of the other side surface of the volute 21, and a limit plate 26 is installed on the outside of the inlet port 25, and the limit plate 26 is connected to the other side surface of the volute 21 through a locking bolt 27, and at the same time, a filter screen 28 is fixedly connected to the inner cavity of the limit plate 26, the limit plate 26 can be installed on the other side surface of the volute 21 through the locking bolt 27, and the limit plate 26 can provide support for the filter screen 28, so that the filter screen 28 can block foreign matter and improve safety.

[0033] See also Figure 1 , Figure 2 , Figure 6 , Figure 7The driving assembly 3 includes a connecting plate 31, which is arranged on one side surface of the volute 22. Four limiting bolts 32 are arranged on one side surface of the connecting plate 31. The bottom ends of the four limiting bolts 32 are connected to the inner cavity of the mounting hole 24. A variable frequency motor 33 is arranged at the center of one side surface of the connecting plate 31. A wheel disc 34 is arranged at the output end of the variable frequency motor 33. The wheel disc 34 is connected to the output end of the variable frequency motor 33 through a clamping bolt 35. Blades 36 are arranged between the wheel discs 34. There are multiple blades 36, and the multiple blades 36 are distributed in a circular array. Clamping grooves 37 are opened on both side surfaces of the wheel disc 34. The inner cavity of the clamping groove 37 is connected to the clamping ring 212.

[0034] The connecting plate 31 in the drive assembly 3 can be installed on one side surface of the volute cover 22, and can also provide an installation base for the limiting bolt 32. Since the bottom end of the limiting bolt 32 is connected to the inner cavity of the mounting hole 24, the connecting plate 31 can be installed on the one side surface of the volute cover 22 through the limiting bolt 32, and the volute cover 22 can provide support for the connecting plate 31, so that it is convenient for the staff to disassemble and repair. Since the frequency conversion motor 33 is fixedly connected to the center position of one side surface of the connecting plate 31, and a wheel disc 34 is installed at the output end of the frequency conversion motor 33, and the wheel disc 34 is connected to the output end of the frequency conversion motor 33 through the clamping bolt 35, the wheel disc 34 can be installed at the output end of the frequency conversion motor 33 through the clamping bolt 35, so that the frequency conversion motor 3 The output end drives the wheel disc 34 to rotate, so that the variable frequency motor 33 can adjust the rotation speed, improve the operation efficiency, and avoid energy waste when running at full load. Since the blades 36 are fixedly connected between the wheels 34, and the blades 36 are fixedly connected, the wheel disc 34 can rotate and drive the multiple blades 36 to rotate to generate centrifugal force, so that the gas can be compressed under the action of the centrifugal force and flow in the radial direction, so as to compress and transport the gas. Since the surfaces of both sides of the wheel disc 34 are provided with engaging grooves 37, and the inner cavity of the engaging grooves 37 is connected to the engaging ring 212, the engaging ring 212 can guide the wheel disc 34, so as to improve the stability of the rotation of the wheel disc 34, so as to improve the safety.

[0035] During operation, when the flame-retardant volute variable frequency centrifugal fan needs to be installed, the installation component 1 is first fixedly connected to the preset position, and then the guide component 2 is fixedly connected to the top of the installation component 1, so that the installation component 1 can provide support for the guide component 2, and then the guide component 2 can be guided, so as to effectively guide the airflow. Since the drive component 3 is fixedly installed in the inner cavity of the guide component 2, the guide component 2 can provide support for the drive component 3, so that the staff can install and disassemble the drive component 3 conveniently, so that the staff can conveniently carry out maintenance and improve the service life. Then, through the drive component 3, the gas can be compressed and transported, so as to promote air circulation, so as to help improve the air transparency in the closed environment and optimize the working environment.

[0036] The mounting plate 11 in the mounting assembly 1 can be fixedly connected at a preset position and can provide a space for the fixing hole 12. Since the fixing hole 12 is elliptical, the staff can connect it to external equipment through the fixing hole, and then the position of the mounting plate 11 can be easily adjusted to improve convenience. Since the top surface of the mounting plate 11 and the positions close to the four fixing holes 12 are fixedly connected with support columns 13, and the top surfaces of the four support columns 13 are fixedly connected with two arc plates 14, and at the same time, reinforcing plates 15 are fixedly connected between the two side walls of the two arc plates 14, the support columns 13 can provide support for the arc plates 14, and then the reinforcing plates 15 can increase the strength of the arc plates 14, so as to provide stable support for the guide assembly 2.

[0037] The volute 21 in the guide assembly 2 can be fixedly connected to the inner cavity of the arc plate 14 and can provide an installation foundation for the volute cover 22. Since the volute cover 22 is connected to the surface of one side of the volute cover 21 through the first fixing bolt 23, the volute cover 22 and the volute cover 21 can form a whole, so that the volute cover 22 and the volute cover 21 can guide the gas, so that it is convenient for the staff to disassemble and install the volute cover 22 and to inspect the interior. Since the volute cover 22 and the volute case 21 are composite materials formed by mineral fibers and resins, and the composite materials have the advantages of high strength and high temperature resistance, the mineral fibers can provide the skeleton and reinforcement of the composite materials, so as to facilitate the maintenance of the internal parts. The resin can fill the gaps between the fibers and firmly bond the fibers together to form an integral structure. This structure enables the composite material to effectively disperse and transfer stress through the joint action of the fibers and the resin when subjected to external force, thereby improving the strength and toughness of the material. The mineral fibers and the resin themselves have good flame retardant and high temperature resistance, and can effectively resist the erosion and spread of flames. Since a mounting hole 24 is provided on one side surface of the volute cover 22 near the center, and the inner cavity of the mounting hole 24 is connected to the drive assembly 3, the drive assembly 3 can be fixedly installed in the center of one side surface of the volute cover 22 through the mounting hole 24, thereby being able to The driving component 3 can drive the gas to be transported so as to facilitate ventilation. A flange 29 is installed at the open end of one side of the volute 21, and the flange 29 is connected to the volute 21 and the volute cover 22 through a second fixing bolt 210. At the same time, connecting holes 211 are opened at the four corners of the surface of one side of the flange 29, so that the flange 29 can be fixedly connected to the open end of the volute 21 through the second fixing bolt 210, and then can be connected to an external device through the connecting hole 211, so as to facilitate the gas transportation. A clamping ring 212 is fixedly connected to the other side surface of the volute 21 and the inner cavity surface of the volute 21, and the outer side of the clamping ring 212 is connected to the driving component 3. Thereby, the locking ring 212 can guide the output end of the drive component 3, thereby improving the stability of the rotation of the output end of the drive component 3, so as to improve safety. Since an inlet port 25 is opened in the center position of the other side surface of the volute 21, and a limit plate 26 is installed on the outside of the inlet port 25, and the limit plate 26 is connected to the other side surface of the volute 21 through a locking bolt 27, and at the same time, a filter screen 28 is fixedly connected to the inner cavity of the limit plate 26, the limit plate 26 can be installed on the other side surface of the volute 21 through the locking bolt 27, and the limit plate 26 can provide support for the filter screen 28, so that the filter screen 28 can block foreign matter and improve safety.

[0038] The connecting plate 31 in the drive assembly 3 can be installed on one side surface of the volute cover 22, and can also provide an installation base for the limiting bolt 32. Since the bottom end of the limiting bolt 32 is connected to the inner cavity of the mounting hole 24, the connecting plate 31 can be installed on the one side surface of the volute cover 22 through the limiting bolt 32, and the volute cover 22 can provide support for the connecting plate 31, so that it is convenient for the staff to disassemble and repair. Since the frequency conversion motor 33 is fixedly connected to the center position of one side surface of the connecting plate 31, and a wheel disc 34 is installed at the output end of the frequency conversion motor 33, and the wheel disc 34 is connected to the output end of the frequency conversion motor 33 through the clamping bolt 35, the wheel disc 34 can be installed at the output end of the frequency conversion motor 33 through the clamping bolt 35, so that the frequency conversion motor 3 The output end drives the wheel disc 34 to rotate, so that the variable frequency motor 33 can adjust the rotation speed, improve the operation efficiency, and avoid energy waste when running at full load. Since the blades 36 are fixedly connected between the wheels 34, and the blades 36 are fixedly connected, the wheel disc 34 can rotate and drive the multiple blades 36 to rotate to generate centrifugal force, so that the gas can be compressed under the action of the centrifugal force and flow in the radial direction, so as to compress and transport the gas. Since the surfaces of both sides of the wheel disc 34 are provided with engaging grooves 37, and the inner cavity of the engaging grooves 37 is connected to the engaging ring 212, the engaging ring 212 can guide the wheel disc 34, so as to improve the stability of the rotation of the wheel disc 34, so as to improve the safety.

[0039] In summary, the device can not only compress and transport gas, but also facilitate disassembly and maintenance by staff, and can facilitate regular inspections by staff to increase service life, and has good flame retardant effect and can suppress the speed of flame spread.

[0040] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A flame retardant volute variable frequency centrifugal fan, characterized in that: include; A guide component (2), wherein the guide component (2) is used to guide wind; A driving component (3), the driving component (3) being arranged in the inner cavity of the guide component (2), the driving component (3) being used to drive wind to move; as well as An installation component (1), the installation component (1) being arranged on the bottom surface of the guide component (2), the installation component (1) being used to provide support for the guide component (2); The mounting assembly (1) comprises a mounting plate (11), the top surface of the mounting plate (11) is provided with fixing holes (12) at four corners, the top surface of the mounting plate (11) is provided with support columns (13) at positions close to the four fixing holes (12), and the top surfaces of the four support columns (13) are provided with two arc-shaped plates (14); The guide assembly (2) comprises a volute (21), the volute (21) being arranged in the inner cavity of the arc-shaped plate (14), a volute cover (22) being arranged on one side surface of the volute (21), the volute cover (22) being connected to one side surface of the volute (21) via a first fixing bolt (23), a mounting hole (24) being provided on one side surface of the volute cover (22) near the center, four mounting holes (24) being provided, the four mounting holes (24) being arranged in a rectangular array, the inner cavity of the mounting hole (24) being connected to the drive assembly (3); A flange (29) is provided at an open end of one side of the volute (21), and the flange (29) is connected to the volute (21) and the volute cover (22) via a second fixing bolt (210). Connection holes (211) are provided at four corners of a surface of one side of the flange (29); The other side surface of the volute (21) and the inner cavity surface of the volute (21) are both provided with a clamping ring (212), and the outer side of the clamping ring (212) is connected to the driving assembly (3); An inlet (25) is provided at a central position on the other side surface of the volute (21), a limit plate (26) is provided outside the inlet (25), the limit plate (26) is connected to the other side surface of the volute (21) via a locking bolt (27), and a filter screen (28) is provided in the inner cavity of the limit plate (26); The drive assembly (3) comprises a connecting plate (31), the connecting plate (31) being arranged on a side surface of the volute (22), the side surface of the connecting plate (31) being provided with four limiting bolts (32), the bottom ends of the four limiting bolts (32) being connected to the inner cavity of the mounting hole (24), a variable frequency motor (33) being arranged at a central position on the side surface of the connecting plate (31), a wheel disc (34) being arranged at the output end of the variable frequency motor (33), the wheel disc (34) being connected to the output end of the variable frequency motor (33) via a locking bolt (35), blades (36) being arranged between the wheel discs (34), a plurality of blades (36) being arranged, and the plurality of blades (36) being distributed in a circular array.

2. The flame-retardant volute variable frequency centrifugal fan according to claim 1, characterized in that: A reinforcing plate (15) is provided between both sides of the two side walls of the two arc-shaped plates (14), and the reinforcing plate (15) is used to increase the strength of the arc-shaped plates (14).

3. The flame-retardant volute variable frequency centrifugal fan according to claim 1, characterized in that: The surfaces of both sides of the wheel disc (34) are provided with engaging grooves (37), and the inner cavity of the engaging groove (37) is connected to the engaging ring (212).

Images