CN206827877U - A kind of elevator traction machine - Google Patents

Abstract

The utility model provides an elevator traction machine, which belongs to the technical field of motors. It solves the technical problems such as poor safety of the existing elevator traction machine. An elevator traction machine, including a motor, a casing and a rotating shaft on the motor, a speed reducer and a brake are arranged between the casing and the rotating shaft, the rotating shaft has a control end and an output end protruding from the casing, and the output end is provided with a passive Safety device, the passive safety device includes a brake disc fixed on the casing and a speed limiting box fixed on the rotating shaft. There are several sliding chambers evenly arranged in the speed limiting box, and a slidable distribution box is arranged in each sliding chamber. Heavy spool, there is also a guide chamber corresponding to the slide chamber one by one in the casing, the slide chamber communicates with the corresponding guide chamber, the guide chamber is slidably connected with a valve column, the valve column is connected with a brake pad, the guide chamber and the corresponding guide chamber are slidably connected. The sliding cavity is filled with hydraulic oil. The utility model has the advantages of good safety performance and the like.

Description

An elevator traction machine

technical field

The utility model belongs to the technical field of motors and relates to an elevator traction machine.

Background technique

The elevator traction machine is the power equipment of the elevator, also known as the elevator host. The function is to convey and transmit power to make the elevator run, control the elevator car to stop, etc. It is composed of motor, brake, coupling, reduction box, traction wheel, frame, guide wheel and auxiliary turning hand wheel. The guide wheels are generally installed on the frame or the load-bearing beam under the frame. Some of the turning hand wheels are fixed on the motor shaft, and some are usually hung on the nearby wall, and then set on the motor shaft when in use.

The existing elevator traction machine has the following problems: 1. The brake of the traditional elevator traction machine is electronically controlled, and the traction machine is located between the elevator car and the wall, and there is a lot of dust and debris, especially when it falls from the elevator door. 2. The brake of the traditional elevator traction machine has no passive safety device. When abnormal conditions such as power failure occur, the elevator car is in danger of falling; 3. The traditional elevator traction The brakes of the machine are used to brake the decelerated rotating shaft to achieve overall braking. The decelerated rotating shaft has a smaller speed and the braking effect is more obvious. However, when the decelerating end of the rotating shaft is braked, the impact on the reduction box is relatively large. , the damage and impact on the coupling is greater; 4. The coupling of the traditional elevator traction machine generally does not have a buffer function. Even if some couplings have a buffer function, the buffer cannot be buffered according to the actual situation of the elevator, that is, , when the elevator stops up and down, the impact force is different. The impact force of the down stop is relatively large, and it is not easy to avoid. The impact force of the down stop is small, but rebound is not allowed. If there is rebound, give Passengers have a stronger sense of weightlessness, which leads to discomfort when taking the elevator; 5. The reducer structure of the traditional elevator traction machine is complex, and it is generally realized by bevel gears. The reduction ratio is obtained through multiple reductions, sacrificing part of the transmission stability.

Contents of the invention

The purpose of this utility model is to provide an elevator traction machine for the above-mentioned problems existing in the existing technology. The technical problem to be solved by the utility model is to increase the passive installation device of the elevator traction machine to improve safety and prevent the car from falling.

The purpose of the utility model can be achieved through the following technical solutions: a traction machine for an elevator, comprising a motor, a casing and a rotating shaft on the motor, characterized in that a speed reducer and a brake are arranged between the casing and the rotating shaft, The rotating shaft has a control end protruding from the casing and an output end, the output end is provided with a passive safety device, and the passive safety device includes a brake disc fixed on the casing and a speed limiter fixed on the rotating shaft. There are several sliding chambers uniformly arranged in the speed limiting box, each of which is provided with a slidable counterweight spool, and the housing is also provided with one-to-one correspondence with the sliding chambers. A guide chamber, the slide chamber communicates with the corresponding guide chamber, a valve column is slidably connected in the guide chamber, the valve column is connected with a brake pad, and hydraulic oil is filled in the guide chamber and the slide chamber.

The linear speed of the wire rope drawn by the elevator traction machine needs to be controlled evenly. If the speed is too high, the counterweight valve core squeezes the hydraulic oil in the sliding chamber to make the valve column move down, and the valve column pushes the brake pad to contact with the brake disc. , causing the linear velocity of the steel wire rope to decrease until the centrifugal force of the counterweight spool is not enough to push the brake pad to contact the brake disc. The linear velocity of the steel wire rope is controlled at a certain set value. When the elevator control circuit or power failure , the elevator car can descend at a steady speed, and there is no case of falling.

Hydraulic oil can improve the smooth rotation of the shaft.

In the above-mentioned elevator traction machine, a reed and a pressure plate are arranged in the sliding chamber, the reed is placed between the counterweight valve core and the pressure plate, and the speed limiting box is provided with a Pressure adjusting bolt on the pressure plate.

The pressure plate and the reed can adjust the pressure of the sliding chamber of the counterweight valve core, and the compression degree of the reed can be changed by adjusting the pressure regulating bolt, thereby adjusting the speed limit standard of the traction machine.

In the above-mentioned elevator traction machine, the reducer includes a main gear fixed on the output end, a side plate 1 located inside the main gear, and a side plate 2 located outside the main gear, the side plate 1 and the side plate There are several planetary gears meshed with the main gear arranged between the two plates. The reducer also includes an output gear with an inner ring gear, the output gear meshes with each planetary gear, and the output gear is fixedly equipped with Output shaft.

The planetary gear is transmitted through the main gear to reduce the speed of the rotating shaft and then transmitted to the output shaft. This reducer clamps the main gear and the planetary gear through the side plate 1, side plate 2 and the output gear to improve the transmission stability and has a simple structure. Reliable, relatively large deceleration.

In the above-mentioned elevator traction machine, the brake includes a turntable connected to the control end through splines, two annular chutes are opened on the turntable, and two ring-shaped chutes are provided on the casing. Corresponding to the second brake disc, the second brake disc can be inserted into the corresponding chute, a number of cylinders are arranged between the two chute, and the push rods of the cylinders are connected to the turntable through plane bearings .

The second brake disc can be in contact with the turntable after being pulled, and realize deceleration and braking through friction.

In the aforementioned traction machine for an elevator, the cylinder is connected to a controller, and the controller is connected in series with a piezoresistor.

In the aforementioned elevator traction machine, the cross section of the chute is trapezoidal, and the outer end of the second brake disc is provided with an insertion end corresponding to the chute. This structure increases the area of friction force, improves the braking strength, and can realize instant stop.

In the aforementioned elevator traction machine, several protrusions are provided on the bottom of the chute.

In the above elevator traction machine, the protrusion is made of rubber material.

The bulge made of rubber material can ensure the accuracy of stopping without slipping; the bulge has a certain buffering effect on the brake disc disc 2 in contact with it. Weaken the impact to avoid damage to parts. Since the brake is set at the control end, its speed is high and the torque is small. Through friction and flexible limit, it can brake quickly and accurately.

In the above-mentioned elevator traction machine, a power generating device is arranged on the control end, the power generating device includes a rotor, a permanent magnet stator and a casing, the permanent magnet stator is fixed on the casing, and the rotor is fixed on the control On the end, the rotor is wound with a coil.

The rotational speed of the shaft of the traction machine is detected by the permanent magnet DC motor. The faster the rotational speed of the shaft, the greater the voltage generated at both ends of the coil. This signal is used to limit the speed of the shaft.

In the aforementioned elevator traction machine, the coil is connected in series with the piezoresistor.

The varistor is in a high-resistance state within a specific voltage range, and cannot trigger the controller. When the voltage reaches the predetermined value of the varistor, the circuit is connected, and the voltage at both ends of the coil can trigger the controller to act on the cylinder, causing the cylinder to return to normal. Pull, so that the brake disc 2 rubs against the turntable, and decelerates the shaft until the speed is lower than the speed of the piezoresistor. Repeatedly, the down speed of the elevator can be controlled after the elevator fails or the power is cut off. Thereby preventing falls.

In the above-mentioned elevator traction machine, a shaft coupling is provided on the output shaft, and the shaft coupling includes an inner shaft sleeve fixedly arranged on the output shaft, and the inner shaft sleeve has a limit block- , the limiting block 1 is provided with arc-shaped insertion piece 1 and insertion piece 2 located on the side of the limiting block 1, and the coupling also includes an outer sleeve sleeved on the inner sleeve, so There is a limit block 2 inside the outer sleeve, and the limit block 2 is provided with a socket 1 corresponding to the insert 1 and a socket 2 corresponding to the insert 2, and the socket 1 and the socket 2 A number of avoidance holes are opened on the outer shaft sleeve between them. The coupling also includes a corrugated energy-absorbing sheet, which is inserted in the avoidance hole, and part of the energy-absorbing sheet extends into the socket one and insert In the hole two, a buffer spring is fixedly connected to the other side of the limit block one, and the two ends of the buffer spring are fixedly connected to the limit block one and the limit block two respectively.

The coupling connects the output shaft and the wire rope puller. When the elevator car goes up to a certain floor and stops, the outer bushing and the inner bushing squeeze the buffer spring. The buffer spring is a steel leaf spring with greater rigidity. , the cushioning effect is not great, and the stop position of the elevator car is accurate; when the elevator car goes down to a certain floor and stops, the inserts 1 and 2 on the inner bushing are inserted into the jack 1 and jack 2 respectively, and are sucked The function of the energy-absorbing sheet, the energy-absorbing sheet has a greater buffering effect on the first and second inserts, and can absorb the impact energy through friction and deformation of the energy-absorbing spring. Furthermore, the first and second inserts are affected The clamping force of the energy-absorbing spring is not easy to be pulled out, so that the elastic impact between the inner bushing and the outer bushing is small, that is to say, when the elevator car stops downward, the vibration and shaking are small.

In the above-mentioned elevator traction machine, as another option, a control device capable of pushing the counterweight spool to move to the outside of the slide chamber is provided in the slide chamber, the control device includes a hydraulic cylinder, and the hydraulic pressure The push rod of the cylinder is fixedly connected with the counterweight spool. The hydraulic cylinder is controlled by a control valve, which is controlled by an external circuit and can assist the brake to perform braking.

Compared with the prior art, the utility model has the following advantages:

1. The linear speed of the wire rope drawn by the elevator traction machine needs to be controlled evenly. If the speed is too high, the counterweight valve core squeezes the hydraulic oil in the sliding chamber to make the valve column move down, and the valve column pushes the brake pad and the brake disc. Once in contact, the linear speed of the steel wire rope decreases until the centrifugal force of the counterweight spool is not enough to push the brake pads to contact the brake disc. The linear speed of the steel wire rope is controlled at a certain set value. When the elevator control circuit or When the power is off, the elevator car can descend at a steady speed, and there is no falling down.

2. The varistor is in a high-resistance state within a specific voltage range and cannot trigger the controller. When the voltage reaches the predetermined value of the varistor, the circuit is connected, and the voltage at both ends of the coil can trigger the controller to act on the cylinder, so that The cylinder pulls back, so that the brake disc 2 rubs against the turntable, and decelerates the rotating shaft until the speed is lower than the speed of the piezoresistor. Repeatedly, the down speed of the elevator can be adjusted after the elevator fails or the power is cut off. control to prevent falls.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the traction machine.

Fig. 2 is a cross-sectional view along the direction A in Fig. 1 .

Fig. 3 is a cross-sectional view along direction B in Fig. 1 .

Fig. 4 is a cross-sectional view along direction C in Fig. 1 .

Fig. 5 is a cross-sectional view along the direction D in Fig. 1 .

Fig. 6 is a schematic diagram of the circuit principle of the power generating device, the brake and the coil.

Fig. 7 is an enlarged view of part of the structure in Fig. 1 .

In the figure, 11, motor; 12, casing; 13, rotating shaft; 14, control end; 15, output end; 21, brake disc one; 22, speed limiting box; 221, sliding cavity; 222, guide cavity; 23 , counterweight spool; 24, spool; 25, brake disc; 26, reed; 27, pressure plate; 28, pressure regulating bolt; 31, main gear; 32, side plate one; 33, side plate two; 34 , planetary gear; 35, output gear; 36, output shaft; 41, turntable; 42, chute; 43, brake disc two; 44, cylinder; 45, controller; 46, varistor; 47, insertion end; 48, protrusion; 51, rotor; 52, permanent magnet stator; 53, shell; 54, coil; 61, inner shaft sleeve; 62, limit block one; 63, insert one; 64, insert two; 65, Outer shaft sleeve; 66, limit block two; 67, jack one; 68, jack two; 69, escape hole; 71, energy-absorbing sheet; 72, buffer spring.

detailed description

The following are specific embodiments of the utility model and in conjunction with the accompanying drawings, the technical solution of the utility model is further described, but the utility model is not limited to these embodiments.

As shown in Figure 1, Figure 2 and Figure 3, the elevator traction machine includes a motor 11, a casing 12 and a rotating shaft 13 are arranged on the motor 11, a speed reducer and a brake are arranged between the casing 12 and the rotating shaft 13, and the rotating shaft 13 has Stretch out the control terminal 14 and output terminal 15 of casing 12, be provided with passive safety device on the output terminal 15, passive safety device comprises the brake disc-21 that is fixed on the casing 12 and the speed limiting box that is fixed on the rotating shaft 13 22. A number of sliding chambers 221 are evenly arranged in the speed limiting box 22, and a slidable counterweight valve core 23 is arranged in each sliding chamber 221, and a guide chamber corresponding to the sliding chambers 221 is also arranged in the casing 12 222, the slide chamber 221 communicates with the corresponding guide chamber 222, the guide chamber 222 is slidingly connected with the valve column 24, the valve column 24 is connected with a brake pad 25, the guide chamber 222 and the slide chamber 221 are filled with hydraulic oil; the elevator The linear speed of the traction machine pulling the wire rope needs to be controlled evenly. If the speed is too high, the counterweight spool 23 squeezes the hydraulic oil in the sliding chamber 221 to move the spool 24 downward, and the spool 24 pushes the brake pad 25 to contact with the brake pad. The contact of the moving disc 1 21 causes the linear velocity of the steel wire rope to decrease until the centrifugal force of the counterweight spool 23 is not enough to push the brake pad 25 to contact the brake disc 1 21, and the linear velocity of the steel wire rope is controlled at a certain set value , when the elevator control circuit or power failure, the elevator car can descend at a steady speed without falling down; the hydraulic oil can improve the rotation stability of the rotating shaft 13 .

The sliding cavity 221 is provided with a reed 26 and a pressure plate 27, the reed 26 is placed between the counterweight spool 23 and the pressure plate 27, and the speed limiting box 22 is provided with a pressure regulating bolt 28 that can lean against the pressure plate 27; the pressure plate 27 and the reed 26 can adjust the pressure of the counterweight spool 23 to compress the sliding chamber 221, and the compression degree of the reed 26 can be changed by adjusting the pressure regulating bolt 28, thereby adjusting the speed limit standard of the traction machine.

As shown in Figures 1 and 4, the speed reducer includes a main gear 31 fixedly arranged on the output end 15, a side plate one 32 positioned inside the main gear 31 and a side plate two 33 positioned outside the main gear 31, side plates one 32 and Several planetary gears 34 meshed with the main gear 31 are arranged between the side plates 2 33, and the speed reducer also includes an output gear 35 with an inner ring gear, the output gear 35 meshes with each planetary gear 34, and the output gear 35 is fixed An output shaft 36 is provided; the planetary gear 34 is transmitted through the main gear 31, the rotating speed of the rotating shaft 13 is reduced, and then transmitted to the output shaft 36. It is clamped with the planetary gear 34 to improve transmission stability, and the structure is simple and reliable, and the reduction ratio is relatively large.

As shown in Figures 1 and 7, the brake includes a turntable 41 connected to the control end 14 through a spline, and two annular chute 42 is opened on the turntable 41, and the casing 12 is provided with corresponding to the two chute 42. Brake disc two 43, the brake disc two 43 can be inserted in the corresponding chute 42, a number of cylinders 44 are arranged between the two chute 42, and the push rods of the cylinders 44 are connected to the rotating disk 41 through plane bearings; The second brake disc 43 can be in contact with the rotating disc 41 after being pulled, so as to realize deceleration and braking through friction.

Cylinder 44 is connected with a controller 45, and controller 45 is connected in series with a piezoresistor 46; This structure increases the area of friction force, improves the braking strength, and can realize instant stop.

The bottom of the chute 42 is provided with some protrusions 48; the protrusions 48 are made of rubber material; the protrusions 48 made of rubber material can ensure the accuracy of stopping without slipping; the protrusions 48 are paired with it The contacted brake disc disc 2 has a certain buffering effect. Under the premise of precise stop, it can weaken the impact as much as possible and avoid damage to parts. Since the brake is set at the control end 14, its speed is high and the torque is small. Through friction and flexible limit, it can brake quickly and accurately.

As shown in Figure 6, wherein, S1 is an auxiliary switch controlling the circuit where the piezoresistor 46 is located, which is used for emergency or opening or closing the function of controlling the speed through voltage, and S2 is the main circuit switch controlling the cylinder 44, and the control terminal 14 is set There is a generator, the generator includes rotor 51, permanent magnet stator 52 and casing 53, permanent magnet stator 52 is fixed on the casing 53, rotor 51 is fixed on the control end 14, is wound with coil 54 on the rotor 51; , to detect the rotational speed of the rotating shaft 13 of the traction machine, the faster the rotational speed of the rotating shaft 13, the greater the voltage generated at both ends of the coil 54, the signal is used to limit the speed of the rotating shaft 13; the coil 54 is connected in series with the piezoresistor 46; The sensitive resistor 46 is in a high-resistance state within a specific voltage range, and the controller 45 cannot be triggered. When the voltage reaches the predetermined value of the piezoresistor 46, the circuit is connected, and the voltage at both ends of the coil 54 can trigger the controller 45 to perform an operation on the cylinder 44. action, the cylinder 44 is pulled back, so that the second brake disc 43 rubs against the rotary disc 41, and the rotating shaft 13 is decelerated until the rotating speed is lower than the rotating speed of the piezoresistor 46, so repeated, it can be used when the elevator fails or the power is cut off. Finally, the down speed of the elevator is controlled to prevent the elevator from falling.

As shown in Fig. 1 and Fig. 5, a shaft coupling is arranged on the output shaft 36, and the shaft coupling includes an inner shaft sleeve 61 fixedly arranged on the output shaft 36, and the inner shaft sleeve 61 has a limit block 1 62, the position limit Block 1 62 is provided with arc-shaped insertion piece 1 63 and insertion piece 2 64 on one side of limit block 62, and the shaft coupling also includes an outer shaft sleeve 65 sleeved on the inner shaft sleeve 61. There is a limit block two 66 in the cover 65, and the limit block two 66 is provided with a jack one 67 corresponding to the insert one 63 and a jack two 68 corresponding to the insert two 64, the jack one 67 and the jack two There are several avoidance holes 69 on the outer bushing 65 between 68, and the coupling also includes a corrugated energy-absorbing piece 71, which is inserted in the avoidance hole 69, and part of the energy-absorbing piece 71 is inserted into the In the hole one 67 and the jack two 68, the other side of the limit block one 62 is fixedly connected with a buffer spring 72, and the two ends of the buffer spring 72 are fixedly connected with the limit block one 62 and the limit block two 66 respectively; The output shaft 36 is connected with the wire rope puller. When the elevator car goes up to a certain floor and stops, the outer bushing 65 and the inner bushing 61 squeeze the buffer spring 72. The buffer spring 72 is a steel leaf spring with a relatively Large rigidity, little cushioning effect, precise stop position of the elevator car; when the elevator car goes down to a certain floor and stops, the first insert 63 and the second insert 64 on the inner shaft sleeve 61 are inserted into the first jack 67 and the second insert respectively. In the socket 2 68, the energy-absorbing sheet 71 acts as a buffer for the first 63 and second 64, and can absorb the impact energy through friction and deformation of the energy-absorbing spring. Furthermore, the first insert 63 and the second insert 64 are clamped by the energy-absorbing spring, so they are not easily pulled out, so that the rebound impact between the inner sleeve 61 and the outer sleeve 65 is relatively small, that is to say When the elevator car goes down, there is less vibration and shaking.

As another option, a control device capable of pushing the counterweight spool 23 to move to the outside of the slide cavity 221 is provided in the slide chamber 221. The control device includes a hydraulic cylinder, and the push rod of the hydraulic cylinder is fixedly connected with the counterweight spool 23. . The hydraulic cylinder is controlled by a control valve, which is controlled by an external circuit and can assist the brake to perform braking.

The specific embodiments described herein are only examples to illustrate the spirit of the present invention. Those skilled in the technical field to which the utility model belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the utility model or go beyond the appended claims defined range.

Claims (10)

1. A kind of elevator traction machine, comprise motor (11), have casing (12) and rotating shaft (13) on the motor (11), it is characterized in that, between described casing (12) and rotating shaft (13) A speed reducer and a brake are provided, the rotating shaft (13) has a control end (14) extending out of the casing (12) and an output end (15), the output end (15) is provided with a passive safety device, the The passive safety device includes a brake disc one (21) fixed on the casing (12) and a speed limiting box (22) fixed on the rotating shaft (13), and a number of slides are evenly arranged in the speed limiting box (22). Cavities (221), each of the sliding chambers (221) is provided with a slidable counterweight spool (23), and the casing (12) is also provided with the sliding chamber (221) one by one Corresponding guide cavity (222), described sliding cavity (221) communicates with corresponding guide cavity (222), described guide cavity (222) is slidingly connected with valve column (24), and described valve column (24) and A brake pad (25) is connected, and hydraulic oil is filled in the guide cavity (222) and the slide cavity (221). 2. An elevator traction machine according to claim 1, characterized in that, a reed (26) and a pressure plate (27) are arranged in the sliding chamber (221), and the reed (26) is placed Between the heavy spool (23) and the pressure plate (27), the speed limiting box (22) is provided with a pressure regulating bolt (28) capable of abutting against the pressure plate (27). 3. An elevator traction machine according to claim 2, characterized in that, the speed reducer comprises a main gear (31) fixedly arranged on the output end (15), a side plate located inside the main gear (31) (32) and the side plate two (33) positioned at the outer side of the main gear (31), between the side plate one (32) and the side plate two (33) are provided with several gears meshed with the main gear (31) Planetary gears (34), this speed reducer also includes an output gear (35) with an internal ring gear, and the output gear (35) is meshed with each planetary gear (34), and the output gear (35) is fixedly provided with output shaft (36). 4. An elevator traction machine according to claim 3, characterized in that the brake includes a turntable (41) connected to the control end (14) through a spline, and two An annular chute (42), the casing (12) is provided with brake disc two (43) corresponding to the two chute (42), and the brake disc two (43) can be inserted in the corresponding In the chute (42), several cylinders (44) are arranged between the two chutes (42), and the push rods of the cylinders (44) are connected with the rotating disk (41) by plane bearings. 5. An elevator traction machine according to claim 4, characterized in that, the cylinder (44) is connected to a controller (45), and the controller (45) is connected in series with a piezoresistor (46) . 6. An elevator traction machine according to claim 5, characterized in that the cross-section of the chute (42) is trapezoidal, and the outer end of the brake disc 2 (43) is provided with a The slot (42) corresponds to the insertion end (47). 7. An elevator traction machine according to claim 6, characterized in that, the bottom of the chute (42) is provided with several protrusions (48); the protrusions (48) are made of rubber material. 8. A kind of elevator traction machine according to claim 7, it is characterized in that, described control end (14) is provided with a generating device, and described generating device comprises rotor (51), permanent magnet stator (52) and casing (53), the permanent magnet stator (52) is fixed on the shell (53), the rotor (51) is fixed on the control end (14), and the coil (54) is wound on the rotor (51). 9. An elevator traction machine according to claim 8, characterized in that the coil (54) is connected in series with the piezoresistor (46). 10. An elevator traction machine according to claim 9, characterized in that, the output shaft (36) is provided with a coupling, and the coupling includes an inner shaft fixed on the output shaft (36). A shaft sleeve (61), the inner shaft sleeve (61) has a limit block one (62), and the limit block one (62) is provided with an arc-shaped Insert one (63) and insert two (64), the coupling also includes an outer sleeve (65) sleeved on the inner sleeve (61), the outer sleeve (65) has Limiting block two (66), said limiting block two (66) is provided with jack one (67) corresponding to inserting piece one (63) and jack two (68) corresponding to inserting piece two (64) ), the outer shaft sleeve (65) between the jack one (67) and the jack two (68) is provided with a number of avoidance holes (69), and the coupling also includes a corrugated energy-absorbing piece (71 ), the energy-absorbing piece (71) is inserted in the avoidance hole (69), and the energy-absorbing piece (71) partially extends into the first jack (67) and the second jack (68), and the limit The other side of the block one (62) is fixedly connected with a buffer spring (72), and the two ends of the buffer spring (72) are fixedly connected with the stop block one (62) and the stop block two (66) respectively.