Automatic refrigerator door opening device

Abstract

The present invention relates to an automatic refrigerator door opening device having a motor-integrated structure and a motor-shaft-fixed-type automatic refrigerator door opening device, in which a lower half part of a motor shaft is rotatably inserted into a lower bearing disposed in a shaft groove of a bearing seat, and the motor shaft is rotatably inserted into a lower bearing disposed in the shaft groove of the bearing seat. The upper end part of the motor shaft is inserted into an upper bearing arranged in an upper shaft seat groove of the cover and is rotatably held, so that the upper end part of the shaft can be prevented from vibrating when the shaft rotates, and noise caused by the vibration of the upper end part of the shaft can be prevented; in the automatic refrigerator door opening device with the fixed motor shaft, not only is the lower half part of the motor shaft inserted and fixed in a shaft hole of a motor seat in a press-in manner, but also the upper end part of the motor shaft is inserted and fixed in a shaft seat groove of an upper cover, so that the upper end part of the shaft can be prevented from vibrating when an outer rotor relatively rotates by taking the shaft as a center; and noise caused by vibration of the shaft can be prevented.

Description

Technical Field

[0001] The present invention relates to an automatic refrigerator door opening device with a motor-integrated structure, which pushes open the refrigerator door after a push rod is pulled out from a sleeve, and more specifically relates to an automatic refrigerator door opening device with a motor-integrated structure, wherein the lower half of the motor shaft is rotatably inserted into a lower bearing of an axis groove arranged in a bearing seat, and the upper end of the motor shaft is inserted into an upper bearing of an upper axis seat groove arranged in a cover and is held in a rotatable manner.

[0002] In addition, the present invention relates to a motor shaft fixed type refrigerator door automatic opening device that pushes the refrigerator door open after the push rod is led out of the sleeve, and more specifically, to a motor shaft fixed type refrigerator door automatic opening device, in which the upper end of the motor shaft is inserted into and fixed in the shaft seat groove of the upper cover, thereby preventing the upper end of the shaft from vibrating when the outer rotor rotates relative to the shaft as the center, and preventing noise caused by the vibration of the shaft. Background Art

[0003] The applicant's Korean Patent Publication No. 10-2022-0088384 (published on June 27, 2022) introduces an "automatic refrigerator door opening device."

[0004] In the automatic opening device for the refrigerator door, a motor is installed inside the sleeve, and the timing drive pulley of the motor and the timing driven pulley of the gear transmission device are connected through a timing belt. The power of the motor is transmitted to the gear transmission device through the timing belt. The final gear device of the gear transmission device is linked to the rack gear formed on the side of the push rod, so that the push rod is led out of the sleeve and the refrigerator door is pushed open.

[0005] However, the disadvantage of the automatic opening device for the refrigerator door is that only the lower end of the motor shaft is fixed by a bearing through a shaft seat, and the upper end of the shaft is not fixed. When the motor shaft rotates, the upper end of the shaft shakes, thereby generating noise and vibration due to the shaking of the shaft. Summary of the invention

[0006] Therefore, an object of the present invention is to provide an automatic opening device for a refrigerator door having an integrated motor structure, wherein the lower half of the motor shaft is rotatably inserted into a lower bearing of an axis groove arranged in a bearing seat, and the upper end of the motor shaft is inserted into an upper bearing of an upper axis seat groove arranged in a cover and is held in a rotatable manner, thereby preventing the upper end of the shaft from vibrating when the shaft rotates and preventing noise from being generated due to the vibration of the upper end of the shaft.

[0007] In addition, another object of the present invention is to provide a motor shaft fixed refrigerator door automatic opening device, in which not only the lower half of the motor shaft is inserted and fixed in the shaft hole of the motor seat in a press-fit manner, but also the upper end of the motor shaft is inserted and fixed in the shaft seat groove of the upper cover, thereby preventing the upper end of the shaft from vibrating when the outer rotor rotates relative to the shaft, and preventing noise from being generated due to the vibration of the shaft.

[0008] In order to achieve the above-mentioned purpose, an example of the refrigerator door automatic opening device with a motor integrated structure according to the present invention is as follows:

[0009] As a refrigerator door automatic opening device with a motor integrated structure, a motor is arranged inside a sleeve, and a timing drive pulley of the motor and a timing driven pulley of a gear transmission device are connected through a timing belt, the power of the motor is transmitted to the gear transmission device through the timing belt, and the final gear device of the gear transmission device is linked with a rack gear formed on the side of a push rod, so that the push rod is led out of the sleeve and then the refrigerator door is pushed open, and an upper cover is combined with the sleeve so as to cover the motor, the gear transmission device and the push rod installed on the sleeve,

[0010] It is characterized in that the bearing seat of the motor is installed on the sleeve, and a lower bearing is arranged in the shaft groove of the bearing seat, and the lower half of the shaft is inserted into the lower bearing, so that the shaft can rotate relative to the bearing seat through the lower bearing, a stator is arranged around the bearing seat, an outer rotor is arranged around the stator, an axial hole is formed in the hub of the outer rotor, and a shaft is inserted into the axial hole of the hub, the shaft is combined with the hub of the outer rotor, so that the shaft rotates through the rotation of the outer rotor, the upper end of the shaft protruding upward through the hub of the outer rotor is inserted into the upper bearing, and the upper bearing is arranged in the upper shaft seat groove of the cover.

[0011] In addition, the present invention is characterized in that the bearing seat of the motor is combined with the sleeve, and the upper end of the shaft is rotatably arranged in the upper shaft seat groove of the cover, and the cover is combined with the sleeve, so that the motor, sleeve and cover are integrated.

[0012] In addition, the upper shaft seat groove of the cover is characterized in that a center circle pocket is formed on the upper bottom surface, and a plurality of guide parts are radially formed from the center circle pocket, a plurality of I-shaped oil storage channels are formed between the guide parts, and oil for lubricating the upper bearing is stored in the center circle pocket and the oil storage channels.

[0013] In addition, the bearing seat is characterized in that an oil storage space divided by a step portion is formed at the lower end of the shaft groove, and a washer is arranged at the step portion, the washer is inserted into the shaft, and the washer is arranged in a washer groove formed at the lower end of the shaft.

[0014] In addition, an example of the motor shaft fixed type refrigerator door automatic opening device according to the present invention is as follows:

[0015] As a refrigerator door automatic opening device with a motor integrated structure, a motor is arranged inside a sleeve, and a timing drive pulley of the motor and a timing driven pulley of a gear transmission device are connected through a timing belt, the power of the motor is transmitted to the gear transmission device through the timing belt, and the final gear device of the gear transmission device is linked with a rack gear formed on the side of a push rod, so that the push rod is led out of the sleeve and then the refrigerator door is pushed open, and an upper cover is combined with the sleeve so as to cover the motor, the gear transmission device and the push rod installed on the sleeve,

[0016] The invention is characterized in that the motor seat of the motor is installed on the sleeve, and the lower half of the shaft is inserted into and fixed in the shaft hole formed in the cylindrical part of the motor seat in a press-fit manner, a stator is installed around the cylindrical part of the motor seat, an outer rotor is arranged around the stator, a hollow part is formed in the hub of the outer rotor, a bearing is inserted in the hollow part, and a shaft is inserted in the bearing, so that the outer rotor can rotate relative to the shaft through the bearing, the upper end of the shaft protruding upward through the bearing is inserted into the shaft seat groove of the upper cover, and a timing drive pulley is installed around the hub.

[0017] In addition, the present invention is characterized in that a motor seat is combined with the sleeve, and the shaft of the motor is pressed and fixed to the motor seat, the upper end of the shaft is inserted into the shaft seat groove fixed to the upper cover, and the sleeve and the upper cover are combined, so that the motor, the sleeve and the upper cover are integrated.

[0018] In addition, the motor seat is characterized in that a coupling hole is formed at the lower end of the cylindrical portion so as to be coupled with a central protrusion formed on the bottom surface of the sleeve, and an axial hole is formed in the cylindrical portion, the axial hole is arranged at the upper part of the coupling hole, a base plate is formed at the lower end of the cylindrical portion, two mounting portions are formed around the base plate in a mutually opposing manner, boss portions are respectively formed at both ends of the mounting portion, coupling grooves are respectively formed in the boss portions, and the coupling grooves of the boss portions are respectively coupled with the protrusions formed on the bottom surface of the sleeve.

[0019] Therefore, the automatic opening device for a refrigerator door according to the present invention has the following effects: it can prevent the noise generated by the vibration of the upper end portion of the shaft, and integrate the motor, the sleeve and the cover, thereby improving the noise generation in structure.

[0020] In addition, the automatic opening device of the refrigerator door according to the present invention reduces the vibration of the timing drive pulley due to the reduced vibration of the shaft, thereby reducing fatigue caused by changes in the tension of the timing belt linked to the timing drive pulley, and prolongs the time for which the upper bearing can be lubricated, thereby ensuring high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 2 is a perspective view showing an automatic opening device for a refrigerator door having a motor-integrated structure according to the present invention.

[0022] Figure 2 1 is an exploded perspective view showing an automatic refrigerator door opening device having a motor-integrated structure according to the present invention.

[0023] Figure 3 The invention is a diagram showing an automatic opening device for a refrigerator door having a motor-integrated structure according to the present invention. Figure 1 Cross-sectional view of line AA.

[0024] Figure 4 It is enlarged to show Figure 3 Detailed diagram of the main parts.

[0025] Figure 5 The upper cover and upper shaft seat groove are shown.

[0026] Figure 6 2 is a perspective view showing a motor shaft fixed type refrigerator door automatic opening device according to the present invention.

[0027] Figure 7 1 is an exploded perspective view showing a motor shaft fixed type refrigerator door automatic opening device according to the present invention.

[0028] Figure 8 The present invention is a diagram showing a motor shaft fixed refrigerator door automatic opening device Figure 6 Cross-sectional view of line AA.

[0029] Fig. 9 It is enlarged to show Figure 8 Detailed diagram of the main parts.

[0030] Fig.10 It is an exploded perspective view showing the motor mount and the sleeve.

[0031] Description of symbols

[0032] 10: Casing 20: Motor

[0033] 30: Gear transmission 40: Timing belt

[0034] 50: Push rod 60: Upper cover

[0035] 210: Bearing seat 220: Lower bearing

[0036] 230: shaft 240: stator

[0037] 250: Outer rotor 260: Upper bearing

[0038] 1000: casing 2000: motor

[0039] 3000: Gear transmission 4000: Timing belt

[0040] 5000: Push rod 6000: Upper cover

[0041] 2100: Motor seat 2200: Shaft

[0042] 2300: stator 2400: outer rotor

[0043] 2500: Bearings DETAILED DESCRIPTION

[0044] Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Such description is not intended to limit the specific implementation of the present invention, but should be understood to include all changes, equivalents and even substitutes within the scope of the present invention. When describing the various drawings, similar reference numerals are used for similar components. Unless otherwise defined, all terms used in this specification, including technical or scientific terms, have the same meaning as those generally understood by people with general knowledge in the technical field to which the present invention belongs.

[0045] In this document, when it is mentioned that a part “comprises” a certain constituent element, this means that unless there is a special description to the contrary, other constituent elements may also be included, rather than being excluded.

[0046] Reference Figures 1 to 4 According to the automatic refrigerator door opening device with a motor-integrated structure of the present invention, a motor 20 is arranged inside the sleeve 10, and a timing drive pulley 21 of the motor 20 and a timing driven pulley 31 of the gear transmission device 30 are connected by a timing belt 40. The power of the motor 20 is transmitted to the gear transmission device 30 through the timing belt 40. The final gear device 32 of the gear transmission device 30 is linked with a rack gear 51 formed on the side of the push rod 50, so that the push rod 50 is moved from the sleeve 10 along the arrow 55 (refer to Figure 1 and Figure 2 ) direction, push open the refrigerator door (not shown), and an upper cover 60 is combined with the sleeve 10 so as to cover the motor 20, the gear transmission device 30 and the push rod 50 installed in the sleeve 10.

[0047] The bearing seat 210 of the motor 20 is installed on the sleeve 10, and a lower bearing 220 is arranged in the shaft groove 211 of the bearing seat 210, and the lower half of the shaft 230 is inserted into the lower bearing 220, so that the shaft 230 can rotate relative to the bearing seat 210 through the lower bearing 220. A stator 240 is arranged around the bearing seat 210, and an outer rotor 250 is arranged around the stator 240. An axial hole 252 is formed in the hub 251 of the outer rotor 250, and the shaft 230 is inserted into the axial hole 252 of the hub 251. The shaft 230 is combined with the hub 251 of the outer rotor 250, so that the shaft 230 rotates through the rotation of the outer rotor 250. The upper bearing 260 is inserted into the upper end of the shaft 230 protruding upward through the hub 251 of the outer rotor 250, and the upper bearing 260 is arranged in the upper shaft seat groove 610 of the cover 60.

[0048] As described above, the present invention inserts the upper end portion of the shaft 230 into the upper bearing 260 of the upper shaft seat groove 610 configured in the cover 60 and holds it in a rotatable form, thereby preventing the upper end portion of the shaft 230 from vibrating when the shaft 230 rotates and preventing noise from being generated due to the vibration of the upper end portion of the shaft 230.

[0049] In addition, the bearing seat 210 of the motor 20 is combined with the sleeve 10, and the upper end of the shaft 230 is rotatably arranged in the upper shaft seat groove 610 of the cover 60, and the sleeve 10 is combined with the cover 60, so that the motor 20, the sleeve 10 and the cover 60 are integrated, thereby improving the generation of noise in structure.

[0050] In the structure as described above, when the timing drive pulley 21 is installed around the hub 251 of the outer rotor 250 and the hub 251 of the outer rotor 250 is rotated, the timing drive pulley 21 installed around the hub 251 rotates, so that the vibration of the timing drive pulley 21 is reduced due to the reduction of the vibration of the shaft 230, thereby reducing the fatigue of the timing belt 40 linked to the timing drive pulley 21 caused by the tension change generated by the vibration of the timing drive pulley 21.

[0051] Reference Figure 5 The upper shaft seat groove 610 of the cover 60 is formed with a center circular pocket 611 on the upper bottom surface, and a plurality of guide portions 612 are radially formed from the center circular pocket 611, and a plurality of I-shaped oil storage channels 613 are formed between the guide portions 612. Oil for lubricating the upper bearing 260 is stored in the center circular pocket 611 and the oil storage channels 613.

[0052] As described above, a space for storing oil on the upper bottom surface of the upper shaft seat groove 610 is ensured, thereby extending the time during which the upper bearing 260 can be lubricated.

[0053] Refer again Figure 4 The bearing seat 210 is formed with an oil storage space 213 divided by a step portion 212 at the lower end of the shaft groove 211, and a washer 270 is arranged in the step portion 212, the washer 270 is inserted into the shaft 230, and the washer 270 is arranged in a washer groove 235 formed at the lower end of the shaft 230.

[0054] Therefore, when the oil stored in the oil storage space 213 is supplied to the lower bearing 220 during the rotation of the shaft 230 and a pressure increase is generated inside the bearing seat 210 during the rotation of the shaft 230, the washer groove 235 of the shaft 230 is stuck around the washer 270, thereby preventing the shaft 230 from rising.

[0055] Reference Figures 6 to 9 According to the automatic refrigerator door opening device with a motor-integrated structure of the present invention, a motor 2000 is arranged inside a sleeve 1000, and a timing drive pulley 2101 of the motor 2000 and a timing driven pulley 3100 of a gear transmission device 3000 are connected by a timing belt 4000, the power of the motor 2000 is transmitted to the gear transmission device 3000 through the timing belt 4000, and the final gear device 3200 of the gear transmission device 3000 is linked with a rack gear 5100 formed on the side of the push rod 5000, so that the push rod 5000 is moved from the sleeve 1000 along the arrow 5500 (refer to Figure 6 and Figure 7 ) direction and then push open the refrigerator door (not shown), and an upper cover 6000 is combined with the sleeve 1000 so as to cover the motor 2000, the gear transmission device 3000 and the push rod 5000 installed on the sleeve 1000.

[0056] The motor seat 2100 of the motor 2000 is installed on the sleeve 1000, and the lower half of the shaft 2200 is inserted into and fixed in the shaft hole 2120 formed in the cylindrical part 2110 of the motor seat 2100 in a press-fit manner. The stator 2300 is installed around the cylindrical part 2110 of the motor seat 2100, and the outer rotor 2400 is arranged around the stator 2300. A hollow part 2420 is formed in the hub 2410 of the outer rotor 2400, and a bearing 2500 is inserted in the hollow part 2420. The shaft 2200 is inserted in the bearing 2500, so that the outer rotor 2400 can rotate relative to the shaft 2200 through the bearing 2500. The upper end of the shaft 2200 protruding upward through the bearing 2500 is inserted into the shaft seat groove 6100 of the upper cover 6000, and a timing drive pulley 2101 is installed around the hub 2410.

[0057] As described above, in the present invention, not only is the lower half of the shaft 2200 inserted and fixed in the shaft hole 2120 of the motor base 2100 in a press-fit manner, but the upper end of the shaft 2200 is also inserted and fixed in the shaft seat groove 6100 of the upper cover 6000, thereby preventing the upper end of the shaft 2200 from vibrating when the outer rotor 2400 rotates relative to the shaft 2200, and preventing noise from being generated due to the vibration of the upper end of the shaft 2200.

[0058] In addition, the motor seat 2100 is combined with the sleeve 1000, and the shaft 2200 to which the motor 2000 is pressed and fixed is inserted into the motor seat 2100, and the upper end of the shaft 2200 is inserted into the shaft seat groove 6100 fixed to the upper cover 6000, and the sleeve 1000 and the upper cover 6000 are combined, so that the motor 2000, the sleeve 1000 and the upper cover 6000 are integrated, thereby improving the generation of noise in structure.

[0059] Reference Fig. 9 and Fig.10 The motor seat 2100 has a coupling hole 2130 formed at the lower end of the cylindrical portion 2110 so as to be coupled with the central protrusion 1110 formed on the bottom surface 1100 of the sleeve 1000, and an axial hole 2120 is formed on the cylindrical portion 2110, and the axial hole 2120 is arranged on the upper part of the coupling hole 2130. A base plate 2140 is formed at the lower end of the cylindrical portion 2110, and two receiving portions 215 are formed around the base plate 2140 in a mutually opposing manner. 0, 2160, boss portions 2170a, 2170b, 2180a, 2180b are respectively formed at the two end portions of the placement portions 2150, 2160, coupling grooves 2190a, 2190b are respectively formed in the boss portions 2180a, 2180b, and the coupling grooves 2190a, 2190b of the boss portions 2180a, 2180b are respectively coupled with raised portions 1120, 1130 formed on the bottom surface 1100 of the sleeve 1000.

[0060] In the structure as described above, when the timing drive pulley 2101 is installed around the hub 2410 of the outer rotor 2400 and the hub 2410 of the outer rotor 2400 is rotated, the timing drive pulley 2101 installed around the hub 2410 rotates, so that the upper end of the shaft 2300 is installed in the shaft seat groove 6100 of the upper cover. Since the vibration of the upper end of the shaft 2300 is reduced, the vibration of the timing drive pulley 2101 is reduced, thereby reducing the fatigue of the timing belt 4000 linked to the timing drive pulley 2101 caused by the tension change caused by the vibration of the timing drive pulley 2101.

[0061] As described above, in the present invention, although specific matters such as specific constituent elements and limited embodiments and drawings are used to illustrate, this is only provided to help a more comprehensive understanding of the present invention. The present invention is not limited to the above-mentioned embodiments. Anyone with general knowledge in the field to which the present invention belongs can make various modifications and variations from these records.

[0062] Therefore, the idea of ​​the present invention is not limited to the illustrated embodiments, and not only the patent claims but also all equivalent or equivalent modifications to the patent claims belong to the scope of the idea of ​​the present invention.

Claims

1. An automatic refrigerator door opening device, as an automatic refrigerator door opening device, a motor (20) is arranged inside a sleeve (10), and a timing drive pulley (21) of the motor (20) and a timing driven pulley (31) of a gear transmission device (30) are connected through a timing belt (40), the power of the motor (20) is transmitted to the gear transmission device (30) through the timing belt (40), and the final gear device (32) of the gear transmission device (30) is linked with a rack gear (51) formed on the side of a push rod (50), so that the push rod (50) is led out of the sleeve (10) and then the refrigerator door is pushed open, and an upper cover (60) is combined with the sleeve (10) so as to cover the motor (20), the gear transmission device (30) and the push rod (50) installed on the sleeve (10), characterized in that The bearing seat (210) of the motor (20) is installed on the sleeve (10), and a lower bearing (220) is arranged in the shaft groove (211) of the bearing seat (210), and the lower half of the shaft (230) is inserted into the lower bearing (220), so that the shaft (230) can rotate relative to the bearing seat (210) through the lower bearing (220), and a stator (240) is arranged around the bearing seat (210), and an outer rotor (250) is arranged around the stator (240). The hub (251) is formed with an axial hole (252), and a shaft (230) is inserted into the axial hole (252) of the hub (251). The shaft (230) is combined with the hub (251) of the outer rotor (250), so that the shaft (230) rotates through the rotation of the outer rotor (250). The upper end of the shaft (230) protruding upward through the hub (251) of the outer rotor (250) is inserted into the upper bearing (260), and the upper bearing (260) is arranged in the upper shaft seat groove (610) of the cover (60).

2. The automatic refrigerator door opening device according to claim 1, characterized in that: The sleeve (10) is combined with a bearing seat (210) of the motor (20), and the upper end of the shaft (230) is rotatably arranged in the upper shaft seat groove (610) of the cover (60), and the sleeve (10) is combined with the cover (60), so that the motor (20), the sleeve (10) and the cover (60) are integrated.

3. The automatic refrigerator door opening device according to claim 1, characterized in that: The upper shaft seat groove (610) of the cover (60) is formed with a central circular pocket (611) on the upper bottom surface, and a plurality of guide portions (612) are radially formed from the central circular pocket (611), and a plurality of straight-line oil storage channels (613) are formed between the guide portions (612). Oil for lubricating the upper bearing (260) is stored in the central circular pocket (611) and the oil storage channels (613).

4. The automatic refrigerator door opening device according to claim 1, characterized in that: The bearing seat (210) is formed with an oil storage space (213) divided by a step portion (212) at the lower end of the shaft groove (211), and a washer (270) is arranged on the step portion (212), the washer (270) is inserted into the shaft (230), and the washer (270) is arranged in a washer groove (235) formed at the lower end of the shaft (230).

5. An automatic refrigerator door opening device, as an automatic refrigerator door opening device, a motor (2000) is arranged inside a sleeve (1000), and a timing drive pulley (2101) of the motor (2000) and a timing driven pulley (3100) of a gear transmission device (3000) are connected through a timing belt (4000), the power of the motor (2000) is transmitted to the gear transmission device (3000) through the timing belt (4000), and the gear transmission device (3000) is connected to the timing driven pulley (3100) of the gear transmission device (3000). The final gear device (3200) of the driving device (3000) is linked with the rack gear (5100) formed on the side of the push rod (5000), so that the push rod (5000) is led out of the sleeve (1000) and the refrigerator door is pushed open, and the sleeve (1000) is combined with an upper cover (6000) so as to cover the motor (2000), the gear transmission device (3000) and the push rod (5000) installed on the sleeve (1000), characterized in that: The motor seat (2100) of the motor (2000) is installed on the sleeve (1000), and the lower half of the shaft (2200) is inserted and fixed in the shaft hole (2120) formed in the cylindrical part (2110) of the motor seat (2100) by pressing, and a stator (2300) is installed around the cylindrical part (2110) of the motor seat (2100), and an outer rotor (2400) is arranged around the stator (2300), and a hub (2410) of the outer rotor (2400) is formed. A hollow portion (2420) is provided, in which a bearing (2500) is inserted, and in which a shaft (2200) is inserted, so that the outer rotor (2400) can rotate relative to the shaft (2200) through the bearing (2500), and the upper end of the shaft (2200) protruding upward through the bearing (2500) is inserted into the shaft seat groove (6100) of the upper cover (6000), and a timing drive pulley (2101) is installed around the wheel hub (2410).

6. The automatic refrigerator door opening device according to claim 5, characterized in that: The sleeve (1000) is combined with a motor seat (2100), and the shaft (2200) of the motor (2000) is pressed and fixed to the motor seat (2100), the upper end of the shaft (2200) is inserted into and fixed to the shaft seat groove (6100) of the upper cover (6000), and the sleeve (1000) and the upper cover (6000) are combined, so that the motor (2000), the sleeve (1000) and the upper cover (6000) are integrated.

7. The automatic refrigerator door opening device according to claim 5, characterized in that: The motor seat (2100) is formed with a coupling hole (2130) at the lower end of the cylindrical portion (2110) so as to be coupled with the central protrusion (1110) formed on the bottom surface (1100) of the sleeve (1000), and an axial hole (2120) is formed on the cylindrical portion (2110), and the axial hole (2120) is arranged on the upper part of the coupling hole (2130). A base plate (2140) is formed at the lower end of the cylindrical portion (2110), and two placement portions ( 2150, 2160), boss portions (2170a, 2170b, 2180a, 2180b) are respectively formed at both ends of the placement portions (2150, 2160), coupling grooves (2190a, 2190b) are respectively formed in the boss portions (2180a, 2180b), and the coupling grooves (2190a, 2190b) of the boss portions (2180a, 2180b) are respectively coupled with protrusions (1120, 1130) formed on the bottom surface (1100) of the sleeve (1000).

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