A rope drive device with a convertible drive mode

Abstract

The present invention relates to the technical field of rehabilitation medical equipment, and particularly to a rope drive device with a convertible drive mode, which includes a left robotic arm mechanism, a right robotic arm mechanism, a force transmission mechanism, a movable pulley mechanism, a spring latch mechanism, a linear slide rail, a guide wheel, and a frame. The spring latch mechanism is used to lock and unlock the movable pulley mechanism, thereby changing the drive mode of the force transmission mechanism, and further changing the motion modes of the left robotic arm mechanism and the right robotic arm mechanism to perform mirror or non-mirror rehabilitation exercise training. The present invention can be generally used for the conversion of the motion mode of a cable-driven double-arm unpowered exoskeleton rehabilitation device, and according to different patients, it can realize the free switching between joint mirror and non-mirror rehabilitation training modes, improve the applicability of the rehabilitation robot to different patients, and ensure the effective progress of rehabilitation training.

Description

Technical Field

[0001] The present invention relates to the technical field of rehabilitation medical equipment, and in particular to a rope transmission device with a convertible transmission mode. Background Art

[0002] As a rehabilitation medical training device, an upper limb double-arm unpowered exoskeleton rehabilitation device can help patients with limb motor function injuries caused by diseases or accidents to carry out rehabilitation training, significantly improve the rehabilitation effect, and free rehabilitation physicians from heavy repetitive physical labor.

[0003] During the upper limb rehabilitation process, for the mid-late treatment of patients with bilateral arm motor function injuries, since the patients have a certain degree of autonomous movement ability at this time, the double-arm unpowered exoskeleton rehabilitation device can be used to perform passive training on the patient's arms. At this time, independent movement of the two arms (non-mirror movement of joints) is required to maximize the recovery of the coordinated movement ability of the two arms. For patients with single-arm motor function injuries, during the early rehabilitation treatment, the healthy side can be relied on to drive the patient to perform mirror movement training, and a certain amount of active training can be completed through the patient's own efforts, fully mobilizing the subjective initiative of the patient's rehabilitation training. At this time, bilateral arm linkage is required. Therefore, in order to meet the rehabilitation training requirements of different patients and different stages, the upper limb double-arm unpowered exoskeleton rehabilitation device needs a special motion mode conversion device. This device realizes the power transmission of the corresponding joints of the two arms based on ropes, and at the same time satisfies the free switching between the two motion modes of the linkage (mirror) and independent movement (non-mirror) of the corresponding joints (such as the flexion / extension joints of the left and right shoulder joints). For this reason, we propose a rope transmission device with a convertible transmission mode. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes a rope transmission device with a convertible transmission mode, which is used for a double-arm unpowered exoskeleton rehabilitation device driven by a rope reel. By converting the transmission mode of the rope, joint mirror and non-mirror rehabilitation movement training can be carried out on the patient to meet the rehabilitation training needs of the patient at different stages.

[0005] The present invention provides the following technical solutions: A rope transmission device with a convertible transmission mode, including a left robotic arm mechanism, a right robotic arm mechanism, a force transmission mechanism, a movable pulley mechanism, a spring pin mechanism, a linear slide rail, a guide wheel, and a frame. The left robotic arm mechanism, the right robotic arm mechanism, the spring pin mechanism, the linear slide rail, and the guide wheel are all fixed on the frame;

[0006] One side of the left robotic arm mechanism is fixed to one end of the first steel wire rope of the force transmission mechanism. The other end of the first steel wire rope bypasses the lower half of the first rope groove of the double-groove pulley of the movable pulley mechanism and is fixed to one side of the right robotic arm mechanism;

[0007] The other side of the left robotic arm mechanism is fixed to one end of the second steel wire rope of the force transmission mechanism. The other end of the second steel wire rope sequentially passes around a guide pulley, the upper semi-circular rope groove of the second rope groove of a double-groove pulley, and a guide pulley, and is fixed to the other side of the right robotic arm mechanism; the first steel wire rope and the second steel wire rope form a closed force transmission loop; the connection mode of the left robotic arm mechanism with the first steel wire rope and the second steel wire rope is opposite to the connection mode of the right robotic arm mechanism with the first steel wire rope and the second steel wire rope.

[0008] The movable pulley mechanism is slidably arranged on a linear slide rail. In the locked state of the spring latch mechanism, the stop latch of the spring latch mechanism is inserted into the hollow shaft of the double-groove pulley, coaxially fixing the movable pulley mechanism to the linear slide rail, and the double-groove pulley of the movable pulley mechanism can rotate along the axis; in the unlocked state of the spring latch mechanism, the double-groove pulley of the movable pulley mechanism can rotate relative to the axis and slide along the linear slide rail.

[0009] Preferably, the left robotic arm mechanism includes a left robotic arm and a left load rope reel.

[0010] The left robotic arm is fixedly connected to the left load rope reel, and the two can rotate coaxially. The left load rope reel is fixed to the frame.

[0011] Preferably, the right robotic arm mechanism includes a right robotic arm and a right load rope reel.

[0012] The right robotic arm is fixedly connected to the right load rope reel, and the two can rotate coaxially. The right load rope reel is fixed to the frame.

[0013] Preferably, the transmission mechanism includes a sleeve, a wire rope sleeve, a first steel wire rope, and a second steel wire rope.

[0014] Both ends of the wire rope sleeve are coaxially fixed in the sleeve by set screws. The sleeve is fixed in the mounting hole of the frame. The first steel wire rope and the second steel wire rope respectively pass through the inner hole of the wire rope sleeve and can slide in the inner hole of the wire rope sleeve.

[0015] Preferably, the linear slide rail includes a slider and a linear guide rail.

[0016] The slider is mounted on the front surface of the linear guide rail. The linear guide rail is vertically fixed to the frame.

[0017] Preferably, the guide pulley includes a U-shaped groove bearing, a shoulder equal-height bolt, and a guide pulley base.

[0018] The U-shaped groove bearing is fixed to the guide pulley base by the shoulder equal-height bolt. The guide pulley base is fixed to the frame.

[0019] Preferably, the movable pulley mechanism includes a front bearing base, a deep groove ball bearing, a bushing, a transmission shaft, a double-groove pulley, and a rear bearing base;

[0020] The bushing is coaxially installed on the transmission shaft, and the double-groove pulley is coaxially fixed on the transmission shaft. The two can rotate coaxially. Both ends of the transmission shaft are coaxially fixed in the deep groove ball bearings, and the deep groove ball bearings are fixed on the inner surfaces of the front bearing base and the rear bearing base. The rear bearing base is fixedly connected to the front surface of the slider. The rear bearing base is fixedly connected to the front surface of the slider by bolts. The transmission shaft is a hollow shaft, and the front bearing base and the rear bearing base are fixedly connected by bolts to form a box structure.

[0021] Preferably, the spring latch mechanism includes a handle, a stop latch, a compression spring, and a spring latch base;

[0022] The handle is fixedly connected to the threaded hole of the stop latch shoulder by thread fit and passes through the inverted L-shaped hole of the spring latch base. The upper and lower end surfaces of the compression spring coincide with the upper bottom surface of the inner hole of the spring latch base and the upper end surface of the stop latch shoulder respectively. The outer circle of the stop latch shoulder is coaxially fitted with the inner hole of the spring latch base, and the spring latch base is fixed on the frame.

[0023] The present invention provides a rope transmission device with a convertible transmission mode, which can realize the conversion between the mirror and non-mirror rehabilitation training modes by converting the transmission mode of the rope. It has the characteristics of convenient operation and good reliability. It can be used as a special rope transmission device for the conversion of the transmission mode of a double-arm unpowered exoskeleton rehabilitation device to meet the rehabilitation training needs of different patients, effectively assist the patient's rehabilitation training, and enhance the effect of rehabilitation training. The movable pulley mechanism is locked or unlocked by the spring latch mechanism. When the movable pulley mechanism is in the locked state, the mirror rehabilitation training mode can be realized. When the movable pulley mechanism is in the unlocked state, the non-mirror rehabilitation training mode can be realized. According to different patients, the free switching between the joint mirror and non-mirror rehabilitation training modes can be realized, improving the applicability of the rehabilitation robot to different patients and ensuring the effective progress of rehabilitation training. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 2 is Figure 1 a schematic diagram of the component structure of each component except the movable pulley mechanism and the spring latch mechanism in

[0026] Figure 3 is Figure 1 an exploded view of the movable pulley mechanism in

[0027] Figure 4 For Figure 1 The exploded view implemented by the spring latch mechanism in the figure;

[0028] Figure 5 For the rope drive schematic diagram of the mirror image rehabilitation training mode;

[0029] Figure 6 For the rope drive schematic diagram of the non - mirror image rehabilitation training mode;

[0030] In the figure: 1. Left robotic arm mechanism; 101. Left robotic arm; 102. Left load rope reel; 2. Right robotic arm mechanism; 201. Right robotic arm; 202. Right load rope reel; 3. Force transmission mechanism; 301. Sleeve; 302. Steel wire rope sleeve; 303. First steel wire rope; 304. Second steel wire rope; 4. Movable pulley mechanism; 401. Front bearing base; 402. Deep groove ball bearing; 403. Bush; 404. Transmission shaft; 405. Double - groove pulley; 4051. First rope groove; 4052. Second rope groove; 406. Rear bearing base; 5. Spring latch mechanism; 501. Handle; 502. Stop latch; 503. Compression spring; 504. Spring latch base; 6. Linear slide rail; 601. Slide block; 602. Linear guide rail; 7. Guide wheel; 701. U - groove bearing; 702. Shoulder - equal height bolt; 703. Guide wheel base; 8. Frame. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] As Figure 1 As shown in the figure, the present application provides a rope drive device with a convertible drive mode, including a left robotic arm mechanism 1, a right robotic arm mechanism 2, a force transmission mechanism 3, a movable pulley mechanism 4, a spring latch mechanism 5, a linear slide rail 6, a guide wheel 7, and a frame 8. The spring latch mechanism 5 is used to lock and unlock the movable pulley mechanism 4, thereby changing the drive mode of the force transmission mechanism 3, and further changing the motion modes of the left robotic arm mechanism 1 and the right robotic arm mechanism 2 to perform mirror image or non - mirror image rehabilitation exercise training.

[0033] As Figure 2As shown in the figure, the left robotic arm mechanism 1 includes a left robotic arm 101 and a left load rope reel 102. The left robotic arm 101 is fixedly connected to the left load rope reel 102, and the two can rotate coaxially. The left load rope reel 102 is fixed to the frame 8. The right robotic arm mechanism 2 includes a right robotic arm 201 and a right load rope reel 202. The right robotic arm 201 is fixedly connected to the right load rope reel 202, and the two can rotate coaxially. The right load rope reel 202 is fixed to the frame 8. The left robotic arm mechanism 1 and the right robotic arm mechanism 2 are arranged symmetrically about the linear guide rail 602 on the left and right;

[0034] The force transmission mechanism 3 includes a sleeve 301, a wire rope sleeve 302, a first wire rope 303, and a second wire rope 304. Both ends of the wire rope sleeve 302 are coaxially fixed inside the sleeve 301 through set screws. The sleeve 301 is fixed in the mounting hole of the frame 8 through set screws. The first wire rope 303 and the second wire rope 304 respectively pass through the inner hole of the wire rope sleeve 302 and can slide in the inner hole of the wire rope sleeve 302. Both ends of the first wire rope 303 are respectively fixed in the rope grooves of the left load rope reel 102 and the right load rope reel 202, and bypass the lower semi-circular rope groove of the double-groove pulley 405. Both ends of the second wire rope 304 are respectively fixed in the rope grooves of the left load rope reel 102 and the right load rope reel 202, and bypass the U-shaped groove bearing 701 and the upper semi-circular rope groove of the double-groove pulley 405. The first wire rope 303 and the second wire rope 304 form a closed force transmission loop. The connection method of the left robotic arm mechanism 1 to the first wire rope 303 and the second wire rope 304 is opposite to the connection method of the right robotic arm mechanism 2 to the first wire rope 303 and the second wire rope 304.

[0035] The linear slide rail 6 includes a slider 601 and a linear guide rail 602. The slider 601 is installed on the front surface of the linear guide rail 602 and can move up and down along the linear guide rail 602. The linear guide rail 602 is provided with mounting holes in the vertical direction and can be vertically fixed to the frame 8 through bolts;

[0036] The guide wheel 7 includes a U-shaped groove bearing 701, a shoulder-equivalent height bolt 702, and a guide wheel base 703. The U-shaped groove bearing 701 is fixed to the guide wheel base 703 through the shoulder-equivalent height bolt 702, and the guide wheel base 703 is fixed to the frame 8.

[0037] As Figure 3As shown in the figure, the movable pulley mechanism 4 includes a front bearing base 401, a deep groove ball bearing 402, a bushing 403, a transmission shaft 404, a double-groove pulley 405, and a rear bearing base 406. The bushing 403 is coaxially installed on the transmission shaft 404. A threaded hole is provided in the circumferential direction of the shoulder end face in the middle of the transmission shaft 404. The double-groove pulley 405 is provided with mounting holes in the circumferential direction and can be coaxially fixed to the transmission shaft 404 through bolts. The two can rotate coaxially. Both ends of the transmission shaft 404 are respectively coaxially fixed in the deep groove ball bearing 402. The deep groove ball bearing 402 is fixed in the mounting holes on the inner surfaces of the front bearing base 401 and the rear bearing base 406. The rear bearing base 406 is fixedly connected to the front surface of the slider 601 through bolts. The transmission shaft 404 is a hollow shaft, and the front bearing base 401 is provided with a through hole along the axial direction of the transmission shaft 404. The front bearing base 401 and the rear bearing base 406 are fixedly connected through bolts to form a box structure.

[0038] As Figure 4 shown in the figure, the spring latch mechanism 5 includes a handle 501, a stop latch 502, a compression spring 503, and a spring latch base 504. The handle 501 is fixedly connected to the threaded hole of the shoulder of the stop latch 502 through threaded fit and passes through the inverted L-shaped hole of the spring latch base 504. The upper and lower end faces of the compression spring 503 coincide with the upper bottom surface of the inner hole of the spring latch base 504 and the upper end face of the shoulder of the stop latch 502 respectively. The outer circle of the shoulder of the stop latch 502 is coaxially fitted with the inner hole of the spring latch base 504. The outer circle of the cylindrical pin of the stop latch 502 can be coaxially fitted with the inner hole of the transmission shaft 404. The stop latch 502 is located directly in front of the transmission shaft 404. The spring latch base 504 is fixed on the frame 8;

[0039] As Figure 5As shown in the figure, for patients with lack or loss of left or right hand motor function and normal motor function of the other arm, it is necessary to convert the transmission mode of the rope into a mirror transmission mode. In this example, for a patient with lack of left hand motor function and normal right hand motor function, mirror rehabilitation exercise training is carried out. First, the spring latch mechanism 5 is converted from the unlocked state to the locked state. By operating the handle 501, the handle 501 is moved in the direction that reduces the compression amount of the compression spring 503 and finally reaches the bottom end of the inverted L-shaped hole on the spring latch base 504. At this time, the compression amount of the compression spring 503 becomes smaller and the length elongates, thereby pushing the stop pin 502 forward along the elongation direction of the compression spring 503, so that the stop pin 502 is inserted into the inner hole of the transmission shaft 404, and the two are coaxially matched, so that the movable pulley mechanism 4 is fixed in the same horizontal plane as the spring latch mechanism 5 and cannot move up and down. After the locking of the movable pulley mechanism 4 is completed, the transmission mode of the rope is converted into a mirror transmission mode; at this time, the patient drives the right robotic arm 201 to move through the right arm, and the right load rope reel 202 rotates coaxially with the right robotic arm 201, so that the first steel wire rope 303 and the second steel wire rope 304 move in the direction of the rotation of the right load rope reel 202 in the force transmission loop, thereby driving the first steel wire rope 303 and the second steel wire rope 304 to move around the left load rope reel 102, so that the left load rope reel 102 rotates, and the rotation direction and speed are the same as those of the right load rope reel 202. The left robotic arm 101 rotates coaxially with the left load rope reel 102, so that the left robotic arm 101 follows the right robotic arm 201 to perform synchronous mirror movement.

[0040] For patients with certain motor abilities in both arms but not fully recovered, it is necessary to convert the transmission mode of the rope into a non-mirror transmission mode, such as Figure 6As shown in the figure, first, the spring latch mechanism 5 is switched from the locked state to the unlocked state. By operating the handle 501, the handle 501 is moved in the direction that increases the compression amount of the compression spring 503 and locked on the upper shoulder of the right end of the inverted L-shaped hole on the spring latch base 504. At this time, the compression amount of the compression spring 503 becomes larger and the length shrinks, and the stop pin 502 moves out of the inner hole of the transmission shaft 404, and the two are no longer coaxially engaged, so that the movable pulley mechanism 4 is in the unlocked state and can move up and down along the linear guide rail 602. After the unlocking of the movable pulley mechanism 4 is completed, the transmission mode of the rope is converted into a non-mirror transmission mode; at this time, the patient's arms drive the left robotic arm 101 and the right robotic arm 201 to move non-mirroringly. At this time, the left load rope reel 102 and the right load rope reel 202 move out of sync, thereby driving the first steel wire rope 303 and the second steel wire rope 304 to move in a closed loop. The forces transmitted by the first steel wire rope 303 and the second steel wire rope 304 finally act on the double-groove pulley 405. When the first steel wire rope 303 bypasses the lower semi-circular rope groove of the double-groove pulley 405, the resultant force F1 acting on the double-groove pulley 405 is upward. When the second steel wire rope 304 bypasses the upper semi-circular rope groove of the double-groove pulley 405, the resultant force F2 acting on the double-groove pulley 405 is downward. When the resultant force acting on the double-groove pulley 405 is upward, the movable pulley mechanism 4 will move upward along the linear guide rail 602. When the resultant force is downward, the movable pulley mechanism 4 will move downward along the linear guide rail 602.

[0041] In the present invention, the conversion between the mirror and non-mirror rehabilitation training modes is realized by converting the transmission mode of the rope, which has the characteristics of convenient operation and good reliability. It can be used as a special rope transmission device for the conversion of the transmission mode of the double-arm non-powered exoskeleton rehabilitation device to meet the rehabilitation training needs of different patients, effectively assist the patient's rehabilitation training, and enhance the effect of rehabilitation training. The movable pulley mechanism 4 is in the locked or unlocked state through the spring latch mechanism 5. When the movable pulley mechanism 4 is in the locked state, the mirror rehabilitation training mode can be realized. When the movable pulley mechanism 4 is in the unlocked state, the non-mirror rehabilitation training mode can be realized. According to different patients, the free switching between the joint mirror and non-mirror rehabilitation training modes can be realized, improving the applicability of the rehabilitation robot to different patients and ensuring the effective progress of rehabilitation training.

[0042] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A rope drive device with a convertible drive mode, characterized in that: it includes a left robotic arm mechanism (1), a right robotic arm mechanism (2), a force transmission mechanism (3), a movable pulley mechanism (4), a spring latch mechanism (5), a linear slide rail (6), a guide pulley (7), and a frame (8). The left robotic arm mechanism (1), the right robotic arm mechanism (2), the spring latch mechanism (5), the linear slide rail (6), and the guide pulley (7) are all fixed on the frame (8); one side of the left robotic arm mechanism (1) is fixed to one end of the first steel wire rope (303) of the force transmission mechanism (3). The other end of the first steel wire rope (303) bypasses the lower semi-circular rope groove of the first rope groove (4051) of the double-groove pulley (405) of the movable pulley mechanism (4) and is fixed to one side of the right robotic arm mechanism (2); the other side of the left robotic arm mechanism (1) is fixed to one end of the second steel wire rope (304) of the force transmission mechanism (3). The other end of the second steel wire rope (304) successively bypasses the left guide pulley (7), the upper semi-circular rope groove of the second rope groove (4052) of the double-groove pulley (405), and the right guide pulley (7) and is fixed to the other side of the right robotic arm mechanism (2). The first steel wire rope (303) and the second steel wire rope (304) form a closed force transmission loop. The connection mode of the left robotic arm mechanism (1) with the first steel wire rope (303) and the second steel wire rope (304) is opposite to the connection mode of the right robotic arm mechanism (2) with the first steel wire rope (303) and the second steel wire rope (304); the movable pulley mechanism (4) is slidably arranged on the linear slide rail (6). In the locked state of the spring latch mechanism (5), the stop latch (502) of the spring latch mechanism (5) is inserted into the hollow shaft of the double-groove pulley (405), coaxially fixing the movable pulley mechanism (4) on the linear slide rail (6), and the double-groove pulley (405) of the movable pulley mechanism (4) can rotate along the axis. In the unlocked state of the spring latch mechanism (5), the double-groove pulley (405) of the movable pulley mechanism (4) can rotate relative to the axis and slide along the linear slide rail (6).

2. The rope drive device with a convertible drive mode according to claim 1, characterized in that: the left robotic arm mechanism (1) includes a left robotic arm (101) and a left load rope reel (102); the left robotic arm (101) is fixedly connected to the left load rope reel (102), and the two can rotate coaxially. The left load rope reel (102) is fixed on the frame (8).

3. The rope drive device with a convertible drive mode according to claim 2, characterized in that: the right robotic arm mechanism (2) includes a right robotic arm (201) and a right load rope reel (202); the right robotic arm (201) is fixedly connected to the right load rope reel (202), and the two can rotate coaxially. The right load rope reel (202) is fixed on the frame (8).

4. A rope drive device with a convertible drive mode according to claim 3, characterized in that: The conduction mechanism includes a sleeve (301), a wire rope sleeve (302), a first wire rope (303), and a second wire rope (304); Both ends of the wire rope sleeve (302) are coaxially fixed inside the sleeve (301) by set screws. The sleeve (301) is fixed in the mounting hole of the frame (8). The first wire rope (303) and the second wire rope (304) respectively pass through the inner hole of the wire rope sleeve (302) and can slide in the inner hole of the wire rope sleeve (302).

5. A rope drive device with a convertible drive mode according to claim 1, characterized in that: The linear slide rail (6) includes a slider (601) and a linear guide rail (602); The slider (601) is installed on the front surface of the linear guide rail (602), and the linear guide rail (602) is vertically fixed on the frame (8).

6. A rope drive device with a convertible drive mode according to claim 1, characterized in that: The guide wheel (7) includes a U-shaped groove bearing (701), a shoulder equal-height bolt (702), and a guide wheel base (703); The U-shaped groove bearing (701) is fixed on the guide wheel base (703) by the shoulder equal-height bolt (702), and the guide wheel base (703) is fixed on the frame (8).

7. A rope drive device with a convertible drive mode according to claim 5, characterized in that: The movable pulley mechanism (4) includes a front bearing base (401), a deep groove ball bearing (402), a bushing (403), a transmission shaft (404), a double-groove pulley (405), and a rear bearing base (406); The bushing (403) is coaxially installed on the transmission shaft (404); the double-groove pulley (405) is coaxially fixed on the transmission shaft (404), and the two can rotate coaxially. Both ends of the transmission shaft (404) are coaxially fixed inside the deep groove ball bearing (402), and the deep groove ball bearing (402) is fixed on the inner surfaces of the front bearing base (401) and the rear bearing base (406). The rear bearing base (406) is fixedly connected to the front surface of the slider (601). The rear bearing base (406) is fixedly connected to the front surface of the slider (601) by bolts. The transmission shaft (404) is a hollow shaft, and the front bearing base (401) and the rear bearing base (406) are fixedly connected by bolts to form a box structure.

8. A rope drive device with a convertible drive mode according to claim 1, characterized in that: The spring latch mechanism (5) includes a handle (501), a stop latch (502), a compression spring (503), and a spring latch base (504); The handle (501) is fixedly connected to the threaded hole of the shoulder of the stop pin (502) through thread fitting, and passes through the inverted L-shaped hole of the spring pin base (504). The upper end surface and the lower end surface of the compression spring (503) coincide with the upper bottom surface of the inner hole of the spring pin base (504) and the upper end surface of the shoulder of the stop pin (502) respectively. The outer circle of the shoulder of the stop pin (502) is coaxially fitted and installed with the inner hole of the spring pin base (504). The spring pin base (504) is fixed on the frame (8).

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