Shoulder strap tensioning device

Abstract

The invention discloses a shoulder strap tensioning device which is used for being installed on an aircraft seat and matched with a parachute strap to form safety constraint. Comprising two groups of shoulder strap units which are integrally mounted together, and each shoulder strap unit comprises a shoulder strap mechanism, an automatic recovery mechanism, a manual release mechanism, an inertia locking mechanism and a manual locking mechanism; the shoulder strap mechanism comprises a strap winding wheel, shoulder straps, locking pieces arranged at the ends of the shoulder straps and locking pins used for locking the locking pieces. The shoulder straps on the two sides bypass the umbrella straps on the two sides respectively and then are locked by the locking pins, and then safety constraint is formed. The automatic recovery mechanism is used for providing shoulder strap recovery force for the strap winding wheel; the manual release mechanism is used for manually operating to drive the locking pin to retreat from the locking sheet to realize manual release; the inertia locking mechanism is used for clamping and stopping the strap winding wheel when the shoulder strap is pulled out too fast; the manual locking mechanism is used for achieving locking through manual operation. According to the device, the shoulder restraint effect of a four-point type or five-point type safety belt can be achieved, two shoulder straps do not need to be used for being bound to the front portion of the trunk of a passenger, and comfort is improved.

Description

Technical Field

[0001] The invention relates to a restraining mechanism on an aircraft seat, in particular to a shoulder strap tightening device. Background Art

[0002] At present, in order to meet the needs of parachuting escape in emergency situations, the seats of domestic and foreign military transport aircraft or other aircraft modified from transport aircraft are equipped with parachutes. These lifesaving parachutes require passengers to wear parachute harnesses after boarding the aircraft and must also wear parachute harnesses throughout the flight so that they can react quickly when parachuting is needed. At the same time, the seats are equipped with four-point or five-point safety belts connected to the passengers (crew seats are generally not equipped with two-point safety belts). The safety belts also need to be worn during the flight to restrain the human torso and protect the passengers in the event of flight overload or emergency landing. Therefore, the passengers will wear two sets of restraint mechanisms, the parachute harness and the safety belt, which has a significant adverse effect on comfort. Summary of the invention

[0003] The object of the present invention is to provide a shoulder strap tensioning device which can cooperate with an umbrella strap to form a safety restraint and can play the role of a four-point or five-point safety belt shoulder restraint, without the need to use two shoulder straps to restrain the front of the occupant's torso, thereby improving comfort.

[0004] The technical solution adopted by the present invention is: A shoulder strap tensioning device is used to be installed on an aircraft seat and cooperate with an umbrella strap to form a safety restraint; it includes two groups of shoulder strap units that are integrated and installed together and arranged on the left and right, each group of shoulder strap units includes a shoulder strap mechanism, an automatic recovery mechanism, a manual release mechanism, an inertial locking mechanism and a manual locking mechanism; the shoulder strap mechanism includes a belt reel, a shoulder strap connected and wound around the belt reel, a locking piece arranged at the end of the shoulder strap, and a locking pin for locking the locking piece, the locking pin has a reset function and is initially in an extended state, and the shoulder straps of the shoulder strap mechanisms on both sides are respectively passed around the umbrella straps on both sides and locked by their respective locking pins The automatic recovery mechanism is used to use a mechanical structure to always provide the take-up wheel with the force to recover the shoulder strap; the manual release mechanism is used to manually operate to drive the locking pin to withdraw from the locking plate to achieve manual release; the inertial locking mechanism is used to utilize the inertia generated when the shoulder strap is pulled out too quickly to stop the take-up wheel and reset itself after stopping; the manual locking mechanism is used to manually operate to switch between the two modes of the take-up wheel. In one mode, the take-up wheel can rotate in both directions so that the shoulder strap can be pulled out and recovered freely, and in the other mode, the take-up wheel can only rotate in one direction so that the shoulder strap cannot be pulled out further but can be recovered.

[0005] Preferably, the automatic recovery mechanism uses a spring as a power source.

[0006] Preferably, the manual release mechanism includes a square shaft, a rocker arm and a pin pulling arm fixed on the square shaft, and a spring sleeved on the locking pin. The pin pulling arm is hinged to one end of the locking pin, and the other end of the locking pin is used to realize the insertion and withdrawal action. The spring is used to provide a reset force for the locking pin. The rocker arm is connected to a release control member on the aircraft seat. The release control member drives the locking pin to overcome the spring force and withdraw through the rocker arm, the square shaft and the pin pulling arm in turn to realize manual release.

[0007] Preferably, the manual release mechanisms on both sides share a square shaft and a rocker arm, and when the release operating member operates the rocker arm, the manual release mechanisms on both sides are manually released synchronously.

[0008] Preferably, the inertial locking mechanism includes an inertial mass block and a tension spring provided on the take-up wheel, and an inner gear ring which is sleeved on and fixed to the take-up wheel. The two groups of inertial mass blocks and tension springs are symmetrically distributed about the axis of the take-up wheel. One end of the inertial mass block is hinged on the outer circle of the take-up wheel, and the other end is connected to one end of the tension spring of the same group. The other end of the tension spring of the same group is connected to the take-up wheel. The centrifugal force generated when the shoulder belt is pulled out too quickly causes the inertial mass block to overcome the tension spring force and extend outward and cooperate with the inner gear ring to stop the take-up wheel. After the take-up wheel is stopped, the centrifugal force disappears and the tension spring drives the inertial mass block to reset.

[0009] Preferably, the inertial locking mechanism also includes a synchronization ring and a connecting rod. The synchronization ring is rotatably mounted on the belt pulley. The two connecting rods are symmetrically arranged about the axis of the belt pulley and correspond to the two inertial mass blocks respectively. The two ends of the connecting rod are respectively hinged to the ejection end of the corresponding inertial mass block and the synchronization ring.

[0010] Preferably, a double-ear piece corresponding to the inertial mass block is provided on the outer circle of the belt pulley, one end of the inertial mass block is connected to the corresponding double-ear piece by a screw, and the screw also serves as a hinge point of the inertial mass block, and a tension spring is connected between the double-ear piece and the inertial mass block.

[0011] Preferably, the manual locking mechanism comprises a long shaft, a latching tooth arranged on the long shaft, a torsion spring sleeved on the long shaft and acting on the latching tooth, and a one-way toothed disc fixed on the take-up wheel, wherein the latching tooth is connected to a locking operating member on the aircraft seat; initially, the latching tooth is stuck on the one-way toothed disc, and the take-up wheel can only rotate in one direction so that the shoulder strap cannot be further pulled out but can be retracted; when the locking operating member drives the latching tooth to overcome the torsion spring force and leave the one-way toothed disc, the take-up wheel can rotate in both directions so that the shoulder strap can be freely pulled out and retracted.

[0012] Preferably, the manual locking mechanisms on both sides share a long axis, and the manual locking mechanisms on both sides work synchronously when the locking operating member is operated.

[0013] Preferably, in each set of shoulder strap units, the take-up wheel is installed in a shell, and the automatic recovery mechanism is installed in a spring protective cover; the two sets of shoulder strap units share a spring protective cover sleeve, and the shells of the two sets of shoulder strap units are respectively located on the left and right sides of the spring protective cover; both ends of the shell and the spring protective cover are open, one end of the shell is docked with the spring protective cover, and the other end is closed by an end cover, and the entire device is installed on the aircraft seat back through the end covers on both sides; the shoulder strap extends out of the shell, and a slot for placing a locking plate is provided on the outside of the shell, and the working end of the locking pin can enter and exit the slot; the part of the take-up wheel close to the automatic recovery mechanism cooperates with the shell through a bearing, and the take-up wheel cooperates with the end cover through a bearing.

[0014] The beneficial effects of the present invention are: The device can cooperate with the parachute strap to form a safety restraint, and can play the role of a four-point or five-point safety belt shoulder restraint. There is no need to use two shoulder straps to restrain the front of the occupant's torso, which improves comfort. The device integrates two sets of shoulder strap units together, which is convenient for installation on aircraft seats (can be used as part of the backrest), and is particularly suitable for aircraft seats that require compact structures and cannot be installed with inertia reel safety belts. In the device, the shoulder straps and automatic recovery mechanisms on both sides are independent of each other, and the shoulder straps on both sides will not get stuck when the occupants turn around or perform other actions even if the lengths of the shoulder straps are pulled out are inconsistent. The device realizes manual release through a manual release mechanism, prevents the shoulder straps from being pulled out too quickly through an inertial locking mechanism, and realizes one-way locking through a manual locking mechanism. It has many functions and is easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the overall appearance diagram of the shoulder strap tensioning device in the present invention.

[0016] Figure 2 It is a schematic diagram of the shoulder strap tensioning device of the present invention after hiding one side housing and the end cover.

[0017] Figure 3 It is the appearance diagram of the take-up wheel in the present invention.

[0018] Figure 4 It is a schematic diagram of the installation of the inertial locking mechanism in the present invention.

[0019] Figure 5 It is an installation cross-sectional view of the inertial locking mechanism in the present invention.

[0020] Figure 6 It is a schematic diagram of the installation of the manual locking mechanism in the present invention.

[0021] Figure 7 It is an installation sectional view of the manual release mechanism in the present invention.

[0022] In the figure: 1-housing, 2-end cover, 3-locking pin, 4-shoulder strap, 5-locking plate, 6-long shaft, 7-square shaft, 8-pin pulling arm, 9-take-up wheel, 10-needle bearing, 11-ball bearing, 12-clockwise mechanism, 13-one-way gear plate, 14-inertial mass block, 15-grip, 16-tension spring, 17-synchronizing ring, 18-connecting rod, 19-inner gear ring, 20-torsion spring, 21-spring, 22-rocker arm, 23-clockwise protection cover. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] The present application provides a shoulder strap 4 tensioning device for installation on an aircraft seat and cooperating with an umbrella strap to form a safety restraint, such as Figure 1 As shown, it is composed of two groups of shoulder strap 4 units that are integrated and installed together and arranged on the left and right; Figures 2 to 7 As shown, each set of shoulder strap 4 units includes a shoulder strap mechanism, an automatic recovery mechanism, a manual release mechanism, an inertial locking mechanism and a manual locking mechanism.

[0025] About the shoulder strap mechanism: like Figure 1 , Figure 2 , Figures 4 to 7 As shown, the shoulder strap mechanism includes a winding wheel 9, a shoulder strap 4, a locking piece 5 and a locking pin 3. The shoulder strap 4 is connected to and wound around the winding wheel 9. The locking piece 5 is arranged at the end of the shoulder strap 4. The locking pin 3 is used to lock the locking piece 5. The locking pin 3 has a reset function and is initially in an extended state. The shoulder straps 4 of the shoulder strap mechanisms on both sides are respectively passed around the umbrella straps on both sides and then locked by their respective locking pins 3 to form a safety restraint (the shoulder strap 4 can directly pass around the umbrella straps or pass around the adapter on the umbrella straps. The specific selection is based on the model of the umbrella straps and the comfort requirements of the occupants. If necessary, a specially designed adapter can be used).

[0026] About automatic recycling institutions: The automatic recovery mechanism is used to use a mechanical structure to always provide the take-up wheel 9 with a force to recover the shoulder strap 4. In this embodiment, preferably, the automatic recovery mechanism uses a spring as a power source, and before the shoulder strap 4 is installed on the take-up wheel 9, the take-up wheel 9 and the spring are first installed together (the spring has no power stored at this time), and then the take-up wheel 9 is rotated in the direction of pulling out the shoulder strap 4 by a suitable number of turns (at this time the spring mechanism 12 stores power), and then the take-up wheel 9 is temporarily fixed, and then the shoulder strap 4 is installed on the take-up wheel 9, after which the spring will provide the take-up wheel 9 with a force to recover the shoulder strap 4.

[0027] About the manual release mechanism: It is used for manual operation to drive the locking pin 3 out of the locking plate 5 to realize manual release. In this embodiment, preferably, as Figure 1 , Figure 2 , Figure 4 , Figure 6 and Figure 7 As shown, the manual release mechanism includes a square shaft 7, a rocker arm 22, a pin pulling arm 8 and a spring 21. The pin pulling arm 8 is fixed on the square shaft 7. The pin pulling arm 8 is hinged to one end of the locking pin 3. The other end of the locking pin 3 is used to realize the insertion and withdrawal action. The spring 21 is sleeved on the locking pin 3. The spring 21 is used to provide a reset force for the locking pin 3. The rocker arm 22 is fixed on the square shaft 7. The rocker arm 22 is connected to a release control member on the aircraft seat (the release control member can be in the form of a pull rod, a cable, etc.). The release control member drives the locking pin 3 to overcome the force of the spring 21 and withdraw to realize manual release through the rocker arm 22, the square shaft 7 and the pin pulling arm 8 in turn; in order to improve the operation efficiency, as Figure 1 As shown, the manual release mechanisms on both sides can share the square shaft 7 and the rocker arm 22, and when the release operating member operates the rocker arm 22, the manual release mechanisms on both sides are manually released synchronously.

[0028] About inertia locking mechanism: It is used to utilize the inertia generated when the shoulder strap 4 is pulled out too fast to stop the belt reel 9 and reset itself after stopping. Figure 2 , Figure 4 and Figure 5 As shown, the inertial locking mechanism includes an inertial mass block 14, a tension spring 16 and an inner gear ring 19. The inertial mass block 14 and the tension spring 16 are arranged on the belt pulley 9. The inner gear ring 19 is sleeved on the belt pulley 9 and fixedly installed. The two groups of inertial mass blocks 14 and the tension spring 16 are symmetrically distributed about the axis of the belt pulley 9. One end of the inertial mass block 14 is hinged on the outer circle of the belt pulley 9, and the other end is connected to one end of the tension spring 16 of the same group. The other end of the tension spring 16 of the same group is connected to the belt pulley 9. When the shoulder belt 4 is pulled out too fast, the centrifugal force generated causes the inertial mass block 14 to overcome the force of the tension spring 16 and extend outward and cooperate with the inner gear ring 19 to stop the belt pulley 9. After the belt pulley 9 is stopped, the centrifugal force disappears and the tension spring 16 drives the inertial mass block 14 to reset; and as Figure 4 and Figure 5 As shown, a synchronization ring 17 and a connecting rod 18 may be additionally provided. The synchronization ring 17 is rotatably sleeved on the belt reel 9. The two connecting rods 18 are symmetrically arranged about the axis of the belt reel 9 and correspond to the two inertial mass blocks 14 respectively. The two ends of the connecting rod 18 are respectively hinged to the ejection ends of the corresponding inertial mass blocks 14 and the synchronization ring 17. This ensures that the two inertial mass blocks are ejected synchronously, avoiding the problem that the inertial mass blocks cannot be ejected synchronously due to different tensions caused by a slight error in the manufacturing of the tension spring 16; and, as shown in FIG. Figure 3 and Figure 4As shown, a double-ear piece corresponding to the inertial mass block 14 can be provided on the outer circle of the belt reel 9, one end of the inertial mass block 14 is connected to the corresponding double-ear piece by a screw, and the screw also serves as a hinge point of the inertial mass block 14, and a tension spring 16 is connected between the double-ear piece and the inertial mass block 14.

[0029] About the manual locking mechanism: It is used to manually switch between two modes of the take-up wheel 9. In one mode, the take-up wheel 9 can rotate in both directions so that the shoulder strap 4 can be freely pulled out and recovered. In the other mode, the take-up wheel 9 can only rotate in one direction so that the shoulder strap 4 cannot be further pulled out but can be recovered. In this embodiment, preferably, as Figure 1 , Figure 2 and Figure 6 As shown, the manual locking mechanism includes a long shaft 6, a latch 15, a torsion spring 20 and a one-way toothed disc 13, the latch 15 is arranged on the long shaft 6, the torsion spring 20 is sleeved on the long shaft 6 and acts on the latch 15, the one-way toothed disc 13 is fixed on the belt reel 9, the latch 15 is connected to a locking control member on the aircraft seat (the locking control member can be in the form of a pull rod, a pull cable, etc.), initially, the latch 15 is stuck on the one-way toothed disc 13, the belt reel 9 can only rotate in one direction so that the shoulder strap 4 cannot be further pulled out but can be recovered, and when the locking control member drives the latch 15 to overcome the force of the torsion spring 20 and leave the one-way toothed disc 13, the belt reel 9 can rotate in both directions so that the shoulder strap 4 can be freely pulled out and recovered; in order to improve the operating efficiency, such as Figure 1 , Figure 2 and Figure 6 As shown, the manual locking mechanisms on both sides can also share the long axis 6, and the manual locking mechanisms on both sides work synchronously when the locking operating member is operated.

[0030] Regarding the installation structure between the various mechanisms, in this embodiment, preferably: Figures 1 to 7As shown, in each group of shoulder strap units 4, the belt reel 9 is installed in the housing 1, and the automatic recovery mechanism is installed in the spring protection cover 23; the two groups of shoulder strap units 4 share a spring protection cover 23 set, and the housings 1 of the two groups of shoulder strap units 4 are respectively located on the left and right sides of the spring protection cover 23; both ends of the housing 1 and the spring protection cover 23 are open, one end of the housing 1 is butt-connected with the spring protection cover 23, and the other end is closed by the end cover 2, and the entire device can be reliably installed on the aircraft seat back by simply improving the structure of the end cover 2; the belt reel 9 adopts a single part, one end of the belt reel 9 is connected to the automatic recovery mechanism, and the other end is connected to the automatic recovery mechanism. A hexagonal boss is set at one end, and the one-way toothed disc 13 is matched on the hexagonal boss and limited by the end cover 2; the shoulder belt 4 extends out of the shell 1, and a slot for placing the locking plate 5 is provided on the outside of the shell 1, and the working end of the locking pin 3 can enter and exit the slot. The inertial mass block 14, the tension spring 16, the synchronous ring 17 and the connecting rod 18 are located in the shell 1, the square shaft 7 and the long shaft 6 are located outside the shell 1, and the inner gear ring 19 is fixed in the shell 1; the part of the belt pulley 9 close to the automatic recovery mechanism is matched with the shell 1 through a needle bearing 10, and the belt pulley 9 is matched with the end cover 2 through a ball bearing 11 to ensure that the belt pulley 9 rotates flexibly.

[0031] The device can cooperate with the umbrella strap to form a safety restraint, and can play the role of a four-point or five-point safety belt shoulder restraint. It is not necessary to use two shoulder straps 4 to restrain the front of the occupant's torso, thereby improving comfort. The device integrates two groups of shoulder straps 4 units together, which is convenient to install on an aircraft seat (can be used as a part of the backrest), and is particularly suitable for aircraft seats that require compact structures and cannot be installed with inertia reel safety belts. In the device, the shoulder straps 4 and the automatic recovery mechanism on both sides are independent of each other, and the shoulder straps 4 on both sides will not get stuck when the occupant turns around or performs other actions even if the lengths of the shoulder straps 4 pulled out are inconsistent. The device realizes manual release through a manual release mechanism, prevents the shoulder straps 4 from being pulled out too quickly through an inertial locking mechanism, and realizes one-way locking through a manual locking mechanism. It has many functions and is easy to use.

[0032] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

Claims

1. A shoulder strap tensioning device, characterized in that: Used to be installed on an aircraft seat and cooperate with an umbrella strap to form a safety restraint; it includes two groups of shoulder strap units that are integrated and installed together and arranged on the left and right, each group of shoulder strap units includes a shoulder strap mechanism, an automatic recovery mechanism, a manual release mechanism, an inertial locking mechanism and a manual locking mechanism; the shoulder strap mechanism includes a belt reel, a shoulder strap connected and wound around the belt reel, a locking piece provided at the end of the shoulder strap, and a locking pin for locking the locking piece, the locking pin has a reset function and is initially in an extended state, and the shoulder straps of the shoulder strap mechanisms on both sides are respectively locked by their respective locking pins after passing through the umbrella straps on both sides. The fixed plate forms a safety restraint; the automatic recovery mechanism is used to use a mechanical structure to always provide the take-up wheel with force to recover the shoulder strap; the manual release mechanism is used to manually operate to drive the locking pin to withdraw from the locking plate to achieve manual release; the inertial locking mechanism is used to utilize the inertia generated when the shoulder strap is pulled out too quickly to stop the take-up wheel and reset itself after stopping; the manual locking mechanism is used to manually operate to switch between the two modes of the take-up wheel. In one mode, the take-up wheel can rotate in both directions so that the shoulder strap can be pulled out and recovered freely, and in the other mode, the take-up wheel can only rotate in one direction so that the shoulder strap cannot be pulled out further but can be recovered.

2. The shoulder strap tensioning device according to claim 1, characterized in that: The automatic recovery mechanism uses a spring as its power source.

3. The shoulder strap tensioning device according to claim 1, characterized in that: The manual release mechanism includes a square shaft, a rocker arm and a pin pulling arm fixed on the square shaft, and a spring sleeved on the locking pin. The pin pulling arm is hinged to one end of the locking pin, and the other end of the locking pin is used to realize the insertion and withdrawal action. The spring is used to provide a reset force for the locking pin. The rocker arm is connected to the release control piece on the aircraft seat. The release control piece drives the locking pin to overcome the spring force and withdraw through the rocker arm, square shaft and pin pulling arm in turn to realize manual release.

4. The shoulder strap tensioning device according to claim 3, characterized in that: The manual release mechanisms on both sides share a square shaft and a rocker arm, and when the operating member operates the rocker arm, the manual release mechanisms on both sides are manually released synchronously.

5. The shoulder strap tensioning device according to claim 1, characterized in that: The inertial locking mechanism includes an inertial mass block and a tension spring arranged on the take-up wheel, and an inner gear ring which is sleeved on and fixed to the take-up wheel. The two groups of inertial mass blocks and tension springs are symmetrically distributed about the axis of the take-up wheel. One end of the inertial mass block is hinged on the outer circle of the take-up wheel, and the other end is connected to one end of the tension spring of the same group. The other end of the tension spring of the same group is connected to the take-up wheel. The centrifugal force generated when the shoulder belt is pulled out too quickly causes the inertial mass block to overcome the tension spring force and extend outward and cooperate with the inner gear ring to stop the take-up wheel. After the take-up wheel is stopped, the centrifugal force disappears and the tension spring drives the inertial mass block to reset.

6. The shoulder strap tensioning device according to claim 5, characterized in that: The inertial locking mechanism also includes a synchronization ring and a connecting rod. The synchronization ring is rotatably mounted on the belt pulley. The two connecting rods are symmetrically arranged about the axis of the belt pulley and correspond to the two inertial mass blocks respectively. The two ends of the connecting rod are respectively hinged to the ejection end of the corresponding inertial mass block and the synchronization ring.

7. The shoulder strap tensioning device according to claim 5, characterized in that: A double-ear piece corresponding to the inertial mass block is provided on the outer circle of the belt reel. One end of the inertial mass block is connected to the corresponding double-ear piece by a screw. The screw also serves as a hinge point of the inertial mass block. A tension spring is connected between the double-ear piece and the inertial mass block.

8. The shoulder strap tensioning device according to claim 1, characterized in that: The manual locking mechanism includes a long shaft, a latching tooth arranged on the long shaft, a torsion spring sleeved on the long shaft and acting on the latching tooth, and a one-way toothed disc fixed on the belt reel, wherein the latching tooth is connected to a locking operating member on the aircraft seat; initially, the latching tooth is stuck on the one-way toothed disc, and the belt reel can only rotate in one direction so that the shoulder strap cannot be further pulled out but can be recovered; when the locking operating member drives the latching tooth to overcome the torsion spring force and leave the one-way toothed disc, the belt reel can rotate in both directions so that the shoulder strap can be freely pulled out and recovered.

9. The shoulder strap tensioning device according to claim 8, characterized in that: The manual locking mechanisms on both sides share a long axis, and the manual locking mechanisms on both sides work synchronously when the locking operating member is operated.

10. The shoulder strap tensioning device according to any one of claims 1 to 9, characterized in that: In each set of shoulder strap units, a belt reel is installed in a shell, and an automatic recovery mechanism is installed in a spring protection cover; two sets of shoulder strap units share a spring protection cover, and the shells of the two sets of shoulder strap units are respectively located on the left and right sides of the spring protection cover; both ends of the shell and the spring protection cover are open, one end of the shell is docked with the spring protection cover, and the other end is closed by an end cover, and the entire device is installed on the aircraft seat back through the end covers on both sides; the shoulder strap extends out of the shell, and a slot for placing a locking plate is provided on the outside of the shell, and the working end of the locking pin can enter and exit the slot; the part of the belt reel close to the automatic recovery mechanism cooperates with the shell through a bearing, and the belt reel cooperates with the end cover through a bearing.

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