CN107600453B

CN107600453B - Lifting device for boarding bridge

Info

Publication number: CN107600453B
Application number: CN201610542071.3A
Authority: CN
Inventors: 梁乐贤; 常绍民; 陈勇
Original assignee: China International Marine Containers Group Co Ltd; Shenzhen CIMC Tianda Airport Support Ltd
Current assignee: Shenzhen CIMC Tianda Airport Support Ltd
Priority date: 2016-07-11
Filing date: 2016-07-11
Publication date: 2021-03-30
Anticipated expiration: 2036-07-11
Also published as: CN107600453A

Abstract

The invention discloses a boarding bridge lifting device which comprises a boarding bridge mechanism, a quick-descending mechanism and a control mechanism. The boarding bridge mechanism comprises a cross beam, two inner sleeves, two outer sleeves and a boarding bridge channel; the quick descending mechanism comprises hydraulic cylinders, at least one hydraulic cylinder is arranged outside each outer sleeve, a cylinder body of each hydraulic cylinder is connected with the outer sleeve, the part above the piston in the cylinder body is an upper oil cavity, and the part below the piston in the cylinder body is a lower oil cavity; the control mechanism comprises an electromagnetic valve, and the electromagnetic valve can control the on-off of a first oil path between the upper oil chamber and the lower oil chamber; when the cylinder body is located at the first position, the electromagnetic valve is closed, the first oil way between the upper oil cavity and the lower oil cavity is disconnected, the oil quantity in the upper oil cavity and the oil quantity in the lower oil cavity are unchanged, and the boarding bridge channel is in a normal state; when the electromagnetic valve is opened, the first oil way between the upper oil cavity and the lower oil cavity is communicated, oil in the upper oil cavity flows to the lower oil cavity, the cylinder body descends to the second position from the first position, and the boarding bridge channel is in a quick descending completion state.

Description

Lifting device for boarding bridge

Technical Field

The invention relates to a mechanism for a boarding bridge in general, in particular to a boarding bridge lifting device.

Background

The boarding bridge is used for being butted with an airplane cabin door, and the height of the cabin door is not fixed, so that the height of the boarding bridge needs to be correspondingly adjusted by matching with the height of the cabin door so as to prevent the cabin door from being damaged due to collision with the cabin door. Generally, a gate protection device is disposed at a butt joint of the boarding bridge, and when an airplane door contacts with a safety boot of the boarding bridge, the boarding bridge needs to be quickly lowered by a certain distance so as to avoid collision with the door.

At present, a boarding bridge is lifted through a boarding bridge lifting mechanism, the lifting mechanism of the existing boarding bridge is driven by a motor and mainly comprises a speed reducing motor, a ball screw pair, an outer sleeve and an inner sleeve, the speed reducing motor is fixed at the top of the outer sleeve, and an output shaft of the speed reducing motor is fixedly connected with a screw of the ball screw pair through a coupler; a nut of the ball screw pair is fixedly connected with the inner sleeve; the inner sleeve is in sliding fit with the outer sleeve and is fixedly connected with a cross beam; the outer sleeve is fixedly connected with the boarding bridge channel. The motor drives the lead screw to slide, so as to drive the outer sleeve to lift. However, because the electromechanical boarding bridge lifting mechanism cannot realize a quick descending function due to the limitation of the ball screw and the speed reduction motor, when the airplane cabin door contacts with the door protection device of the boarding bridge, the descending speed of the boarding bridge is slow, and the boarding bridge collides with the cabin door, so that the cabin door is damaged.

Therefore, there is a need for a boarding bridge lifting device to achieve rapid descent of such electromechanical boarding bridges.

The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

A primary object of the present invention is to overcome at least one of the drawbacks of the prior art described above and to provide a boarding bridge lifting device that enables a quick descent of the boarding bridge.

In order to achieve the above object, the present invention provides a boarding bridge lifting device, which comprises a boarding bridge mechanism, a quick-lowering mechanism and a control mechanism.

The boarding bridge mechanism comprises a cross beam, two inner sleeves fixed on the cross beam, two outer sleeves sleeved outside the inner sleeves in a sliding manner and a boarding bridge channel fixedly connected between the two outer sleeves;

the quick descending mechanism comprises hydraulic cylinders, at least one hydraulic cylinder is arranged outside each outer sleeve, a cylinder body of each hydraulic cylinder is connected with the outer sleeve, a piston of each hydraulic cylinder is slidably positioned in the cylinder body, the part, above the piston, in the cylinder body is an upper oil cavity, and the part, below the piston, in the cylinder body is a lower oil cavity; and

the control mechanism comprises an electromagnetic valve, and the electromagnetic valve can control the on-off of a first oil path between the upper oil chamber and the lower oil chamber;

when the cylinder body is located at the first position, the electromagnetic valve is closed, the first oil way between the upper oil cavity and the lower oil cavity is disconnected, the oil quantity in the upper oil cavity and the oil quantity in the lower oil cavity are unchanged, and the boarding bridge channel is in a normal state; when the electromagnetic valve is opened, the first oil way between the upper oil cavity and the lower oil cavity is communicated, oil in the upper oil cavity flows to the lower oil cavity, the cylinder body descends to the second position from the first position, and the boarding bridge channel is in a quick descending completion state.

Compared with the prior art, the invention has the beneficial effects that: compared with the existing lifting mechanism driven only by a motor, the lifting mechanism quickly responds to a descending instruction through the electromagnetic valve, the cylinder body descends immediately when the electromagnetic valve is opened, the outer sleeve and the boarding bridge descend synchronously, the reaction in the whole process is quick, the time is short, and the boarding bridge descends immediately before contacting with the cabin door, so that the contact with the cabin door is avoided, and the collision damage of the cabin door is prevented. Therefore, the boarding bridge lifting device can effectively protect the cabin door.

Drawings

Various objects, features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, when considered in conjunction with the accompanying drawings. The drawings are merely exemplary of the invention and are not necessarily drawn to scale. In the drawings, like reference characters designate the same or similar parts throughout the different views. Wherein:

fig. 1 is a front view of a boarding bridge lifting device according to an exemplary embodiment.

Fig. 2a is a partial schematic view of the boarding bridge lifting device shown in fig. 1.

Fig. 2b is a partial sectional view of the boarding bridge lifting device shown in fig. 2 a.

Fig. 3a is a schematic view of the cylinder in the first position.

Fig. 3b is a schematic cross-sectional view of the cylinder in the first position.

Fig. 4a is a schematic view of the cylinder in the second position.

Fig. 4b is a schematic cross-sectional view of the cylinder in a second position.

Fig. 5a is a schematic view of the cylinder in a third position.

Fig. 5b is a schematic cross-sectional view of the cylinder in a third position.

FIG. 6 is a hydraulic system diagram in accordance with an exemplary embodiment.

FIG. 7 is a hydraulic system diagram in accordance with another exemplary embodiment.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted.

Relative terms, such as "lower" or "bottom" and "upper" or "top," may be used in embodiments to describe a relative relationship of one component of an icon to another component. It will be appreciated that if the device of the icon is turned upside down, components described as being on the "lower" side will be components on the "upper" side. Further, when a layer is "on" another layer or a substrate, it may mean "directly on" the other layer or the substrate, or that the layer is on the other layer or the substrate, or that the other layer is interposed between the other layer and the substrate.

The invention provides a boarding bridge lifting device, which is used for realizing the rapid descending of a boarding bridge and comprises a boarding bridge mechanism 10, a rapid descending mechanism 20 and a control mechanism 30.

As shown in fig. 2a and 2b, the boarding bridge mechanism 10 includes a beam 11, two inner tubes 12 fixed on the beam 11, two outer tubes 13 slidably sleeved outside the inner tubes 12, and a boarding bridge passage 14 fixedly connected between the two outer tubes 13.

The quick descending mechanism 20 comprises hydraulic cylinders 21, at least one hydraulic cylinder 21 is arranged outside each outer sleeve 13, a cylinder body 211 of each hydraulic cylinder 21 is connected with the outer sleeve 13, a piston 212 of each hydraulic cylinder 21 is slidably positioned in the cylinder body 211, the part, above the piston 212, in the cylinder body 211 is an upper oil chamber C1, and the part, below the piston 212, in the cylinder body 211 is a lower oil chamber C2.

As shown in fig. 6, the control mechanism 30 includes a solenoid valve 31, and the solenoid valve 31 is capable of controlling on/off of the first oil passage L1 between the upper oil chamber C1 and the lower oil chamber C2.

When the cylinder body 211 is at the first position, the electromagnetic valve 31 is closed, the first oil path L1 between the upper oil chamber C1 and the lower oil chamber C2 is cut off, the oil amount in the upper oil chamber C1 and the oil amount in the lower oil chamber C2 are not changed, and the boarding bridge 14 is in a normal state, i.e., a state of not descending, as shown in fig. 3a and 3 b; when the electromagnetic valve 31 is opened, the first oil passage L1 between the upper oil chamber C1 and the lower oil chamber C2 is communicated, the oil in the upper oil chamber C1 flows into the lower oil chamber C2, the cylinder body 211 descends from the first position to the second position, and the boarding bridge passage 14 is in a quick descent completion state, as shown in fig. 4a and 4 b.

Therefore, the boarding bridge lifting device controls the oil circuit of the hydraulic cylinder through the electromagnetic valve, the oil in the oil cavity limits the cylinder body under the normal state, the cylinder body and the outer sleeve of the hydraulic cylinder are kept at higher positions, when the control mechanism receives a signal to quickly drop, the electromagnetic valve is opened, the oil is allowed to flow between the upper cavity and the lower cavity, the limit on the cylinder body is relieved, the outer sleeve and the cylinder body of the hydraulic cylinder are driven to drop under the self-weight action of the boarding bridge, and the quick drop of the boarding bridge is completed.

Therefore, compared with the existing lifting mechanism which drives the screw rod to slide only through the motor so as to drive the outer sleeve and the boarding bridge to descend, the lifting mechanism has the advantages that the electromagnetic valve quickly responds to a descending instruction, the cylinder body descends immediately when the electromagnetic valve is opened, the outer sleeve and the boarding bridge descend synchronously, the reaction is quick in the whole process, the time is short, the boarding bridge descends quickly immediately before contacting with the cabin door, the contact with the cabin door is avoided, and the cabin door is prevented from being collided and damaged. Therefore, the boarding bridge lifting device can effectively protect the cabin door.

In this embodiment, as shown in fig. 3a and 4b, two hydraulic cylinders 21 are symmetrically disposed outside each outer sleeve 13, and when the electromagnetic valve 31 is opened, the cylinders 211 of the two hydraulic cylinders 21 are synchronously lowered to the second position.

As shown in fig. 3a and 3b, when the cylinder block 211 is in the first position, the upper oil chamber C1 is filled with oil, and the piston 212 is at the lowest position in the cylinder block 211. As shown in fig. 4a and 4b, when the lower oil chamber C2 is filled with oil and the piston 212 is at the highest position in the cylinder block 211, the cylinder block 211 is at the second position.

In this embodiment, as shown in fig. 2a and 2b, the fast descending mechanism 20 further includes a top cover 22 and a transition sleeve 23, the top cover 22 is located above the outer sleeve 13, the transition sleeve 23 is fixed on the lower surface of the top cover 22 and is sleeved outside the outer sleeve 13, the cylinder 211 is hinged to the outer sleeve 13, and the piston 212 is hinged to the transition sleeve 23. Because the hydraulic cylinder 21 is respectively hinged with the outer sleeve 13 and the transition sleeve 23, when the hydraulic cylinder 21 is installed and inclined, and cannot be lifted vertically, the hydraulic cylinder 21 is allowed to rotate relative to the outer sleeve 13 and the transition sleeve 23 in the movement process, and the movement is prevented from being blocked. The connection mode of the hydraulic cylinder 21 is not limited to this, and may be fixed connection, bolt connection, or the like, and any mode capable of achieving mechanical connection is included in the scope of the present application.

In this embodiment, the inner circumference of the transition sleeve 23 is provided with a first baffle 231, and the outer circumference of the upper end of the outer sleeve 13 is provided with a second baffle 131; during the process of lowering the cylinder 211 from the first position, the second baffle 131 descends along with the outer sleeve 13 onto the first baffle 231, and is stopped by the first baffle 231, and the cylinder 211 is at the second position, as shown in fig. 4a and 4 b.

In this embodiment, the lower surface of second baffle 131 is provided with buffer block 132, when second baffle 131 descends onto first baffle 231 along with outer sleeve 13, buffer block 132 directly contacts first baffle 231, and buffer block 132 may be rubber, so as to reduce the impact on hydraulic cylinder 21 when boarding bridge descends quickly.

According to an embodiment of the present invention, the present embodiment can not only realize the above-mentioned rapid descending, but also perform normal ascending and descending, and the mechanism and operation related to the normal ascending and descending will be described in detail below.

As shown in fig. 2a and 2b, the boarding bridge lifting device further includes a normal lifting mechanism 40, which includes a motor 41 and a screw pair 42, the motor 41 is fixed above the top cover 22, a screw 421 of the screw pair 42 is fixedly connected with an output shaft 411 of the motor 41, and a nut 422 of the screw pair 42 is in threaded connection with the screw 421 and is fixedly connected with the inner sleeve 12; a first bearing 43 is arranged between the top cover 22 and the screw rod. When the cylinder 211 is at the second position, the output shaft 411 of the motor 41 rotates in the first direction to lower the lead screw 421, and the upper cover, the driving transition sleeve 23 and the outer sleeve 13 are lowered accordingly. A bushing 44 and a second bearing 45 may be disposed below the nut 422, the bushing 44 is fixed below the nut 422 and sleeved on the outer circumference of the screw 421, and the second bearing 45 is disposed below the bushing 44. The first bearing 43 and the second bearing 45 may be self-aligning bearings to allow slight radial movement during sliding of the lead screw 421, preventing the lead screw 421 from being broken.

In this embodiment, the lower end of the inner tube 12 is provided with a stopper 15, and when the outer tube 13 descends to be stopped by the stopper 15, the cylinder 211 is in the third position, as shown in fig. 5a and 5 b. The stopping portion 15 is in the form of a boss in the embodiment, however, the structure of the stopping portion 15 is not limited to this, for example, other protruding structures may be provided outside the inner sleeve 12, and therefore, it should be understood that any structure capable of realizing a stopping function is covered in the protection scope of the present invention.

In the present embodiment, as shown in fig. 5a and 5b, when the cylinder 211 is in the third position, the output shaft 411 of the motor 41 continues to rotate in the first direction, so that the lead screw 421 descends, the outer sleeve 13 is stopped by the stopping portion 15 and cannot descend, and the piston 212 can descend to return to the lowest position in the cylinder 211, i.e. the initial position, as shown in fig. 2a and 2 b.

After the boarding bridge is completely descended, the boarding bridge lifting device needs to be restored to the normal position as shown in fig. 3a and 3b for the next use. The motor 41 can be reversed to raise the lead screw 421, and the hydraulic cylinder 21 and the outer sleeve 13 in the boarding bridge lifting device shown in fig. 2a and 2b are driven to rise. The present embodiment can be implemented in the following manner.

In the present embodiment, the electromagnetic valve 31 may be a one-way electromagnetic valve, when the electromagnetic valve 31 is closed, the oil in the cylinder block 211 is allowed to flow from the lower oil chamber C2 to the upper oil chamber C1, while the oil in the upper oil chamber C1 cannot flow to the lower oil chamber C2; when the electromagnetic valve 31 is opened, the oil in the cylinder block 211 is allowed to flow between the upper oil chamber C1 and the lower oil chamber C2.

As shown in fig. 2a and 2b, when the cylinder block 211 is at the third position and the piston 212 descends to the lowest position in the cylinder block 211, the solenoid valve 31 is closed, and thus, the oil in the upper oil chamber C1 cannot flow to the lower oil chamber C2, so that the cylinder block 211 cannot move relative to the piston 212. At this time, the output shaft 411 of the motor 41 rotates in the second direction to lift the lead screw 421, the piston 212 lifts therewith, and the cylinder 211 and the outer sleeve 13 are lifted to the first position of the cylinder 211, as shown in fig. 3a and 3 b. Wherein the second direction is opposite to the first direction. Thereby, the boarding bridge elevating apparatus is restored to the normal state as shown in fig. 3a and 3 b.

In this embodiment, the quick drop mechanism 20 further includes a hinge holder 24, which includes a first hinge portion 241 and a second hinge portion 242, one end of the first hinge portion 241 is hinged to the transition sleeve 23 at a first hinge point, one end of the second hinge portion 242 is hinged to the outer sleeve 13 at a second hinge point, the other end of the first hinge portion 241 is hinged to the other end of the second hinge portion 242, and the first hinge point is parallel to the axis of the second hinge point.

The torque generated by the motor 41 is transmitted to the transition sleeve 23, and then from the transition sleeve 23 to the outer sleeve 13 via the hinge holder 24. The inner sleeve 12, the outer sleeve 13 and the transition sleeve 23 are polygonal with the same shape, and each side of the outer sleeve 13 and the transition sleeve 23 is provided with the hinge retainer 24. Since the inner sleeve 12 is fixed, the outer sleeve 13 will not rotate, and the hinge holder 24 can prevent the motor 41 and the transition sleeve 23 from unnecessary rotation, thereby stopping rotation. Meanwhile, the hinge holder 24 prevents the transition sleeve 23 and the outer sleeve 13 from being deviated from each other, and maintains the positional relationship therebetween.

In this embodiment, as shown in fig. 2a and 2b, the inner sleeve 12 and the outer sleeve 13 are both provided with the slider 16, and the slider 16 is located between the inner sleeve 12 and the outer sleeve 13. Therefore, the outer sleeve 13 is prevented from rubbing against the inner sleeve 12 when moving, and smooth sliding of the outer sleeve 13 outside the inner sleeve 12 is ensured. Among them, the slide block 16 may be uniformly arranged between the inner sleeve 12 and the outer sleeve 13. For example, the inner and outer sleeves 13 are square tubes, and the sliders 16 may be disposed on four surfaces of the square tubes. It should be noted that the position and number of the sliders 16 are not limited thereto, and may be located in the middle of the inner sleeve 12. The sliders 16 may be disposed on the inner and outer sleeves 13, respectively, or may be disposed entirely on the inner sleeve 12 or the outer sleeve 13.

FIG. 6 illustrates an embodiment of a hydraulic system diagram. In the present embodiment, the control mechanism 30 may further include a throttle valve 32, which is located on the first oil passage L1, for example, downstream of the solenoid valve 31, and which controls the flow rate of oil from the upper oil chamber C1 into the lower oil chamber C2, thereby controlling the fast descent speed of the outer sleeve 13.

As shown in fig. 6, control mechanism 30 may further include a first relief valve 33 on a second oil passage L2 connected in parallel with first oil passage L1, and when first relief valve 33 is opened, oil in upper oil chamber C1 is allowed to flow into lower oil chamber C2 via second oil passage L2. Therefore, when the oil pressure in the upper oil chamber C1 becomes excessive, the first relief valve 33 can be opened to release part of the oil in the upper oil chamber C1 to ensure the safety of the apparatus. For example, when the outer sleeve 13 on one side is accidentally lowered due to a fault, the first overflow valve 33 on the other side can be opened, so that the outer sleeve 13 on the other side is lowered, and the safety of the boarding bridge is ensured.

As shown in FIG. 6, the control mechanism 30 may also include an accumulator 34 for replenishing or absorbing hydraulic oil in the lower oil chamber C2.

FIG. 7 illustrates another embodiment of a hydraulic system diagram. In this embodiment, the boarding bridge lifting device further includes a power unit 50, and the energy storage device 34 is eliminated. As shown in fig. 7, the third oil passage L3 of the power unit 50 is connected in parallel to the first oil passage L1 of the control unit 30. The power unit 50 includes an oil tank 51, a filter 52, a hydraulic pump 53, a check valve 54, and a second relief valve 55; when the hydraulic pump 53 is operated, the hydraulic oil in the oil tank 51 can be pressed into the upper oil chamber C1 of the hydraulic cylinder 21, and at the same time, the oil in the lower oil chamber C2 flows back into the oil tank 51, and the piston 212 descends to the lowest position in the cylinder body 211, that is, the quick-descent mechanism 20 returns to the initial position.

In addition, in the present embodiment, the control mechanism 30 may further include a travel switch 35 disposed on the outer wall of the transition sleeve 23, as shown in fig. 3a and 3b, when the cylinder 211 is in the first position, the travel switch 35 is not triggered; when the piston 212 of the hydraulic cylinder 21 is not at the lowest position of the cylinder 211, the stroke switch 35 is triggered to determine whether or not the boarding bridge 14 performs the quick descent operation. That is, when the travel switch 35 is triggered, the worker is notified that the boarding bridge gate 14 is performing the quick-lowering operation, and the worker controls the boarding bridge elevating device to perform the subsequent normal elevating operation to return to the normal state.

In summary, the boarding bridge lifting device controls the oil path of the hydraulic cylinder through the electromagnetic valve, in a normal state, oil in the oil cavity limits the cylinder body, so that the cylinder body and the outer sleeve of the hydraulic cylinder are both kept at a higher position, when the control mechanism receives a signal to quickly drop, the electromagnetic valve is opened, oil is allowed to flow between the upper cavity and the lower cavity, the limit on the cylinder body is removed, the outer sleeve and the cylinder body of the hydraulic cylinder are driven to drop under the self-weight action of the boarding bridge, and the quick drop of the boarding bridge is completed. Therefore, compared with the existing lifting mechanism which drives the screw rod to slide only through the motor so as to drive the outer sleeve and the boarding bridge to descend, the lifting mechanism has the advantages that the electromagnetic valve quickly responds to a descending instruction, the cylinder body descends immediately when the electromagnetic valve is opened, the outer sleeve and the boarding bridge descend synchronously, the reaction is quick in the whole process, the time is short, the boarding bridge descends quickly immediately before contacting with the cabin door, the contact with the cabin door is avoided, and the cabin door is prevented from being collided and damaged. Therefore, the boarding bridge lifting device can effectively protect the cabin door.

While the present invention has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration, rather than of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.

Claims

1. A boarding bridge lifting device comprising:

a boarding bridge mechanism comprising: the aerobridge comprises a crossbeam, two inner sleeves fixed on the crossbeam, two outer sleeves sleeved outside the inner sleeves in a sliding manner and an aerobridge channel fixedly connected between the two outer sleeves;

the quick descending mechanism comprises hydraulic cylinders, at least one hydraulic cylinder is arranged outside each outer sleeve, a cylinder body of each hydraulic cylinder is connected with the outer sleeve, a piston of each hydraulic cylinder can be slidably positioned in the cylinder body, the part, above the piston, in the cylinder body is an upper oil cavity, and the part, below the piston, in the cylinder body is a lower oil cavity; and

when the cylinder body is located at the first position, the electromagnetic valve is closed, the first oil way between the upper oil cavity and the lower oil cavity is disconnected, the oil quantity in the upper oil cavity and the oil quantity in the lower oil cavity are unchanged, and the boarding bridge channel is in a normal state; when the electromagnetic valve is opened, a first oil path between the upper oil cavity and the lower oil cavity is communicated, oil in the upper oil cavity flows to the lower oil cavity, the cylinder body descends to a second position from a first position, the boarding bridge channel is in a quick descending completion state, when the cylinder body is at the first position, the upper oil cavity is filled with oil, the piston is at the lowest position in the cylinder body, the lower oil cavity is filled with oil, and when the piston is at the highest position in the cylinder body, the cylinder body is at the second position;

the boarding bridge lifting device also comprises a normal lifting mechanism, the normal lifting mechanism comprises a motor and a lead screw pair, the motor is fixed above the top cover, a lead screw of the lead screw pair is fixedly connected with an output shaft of the motor, a nut of the lead screw pair is in threaded connection with the lead screw and is fixedly connected with the inner sleeve, and a first bearing is arranged between the top cover and the lead screw; when the cylinder body is located at the second position, the output shaft of the motor rotates in the first direction to enable the screw to descend, the upper cover drives the transition sleeve and the outer sleeve to descend, a second bearing is arranged below the nut and on the periphery of the screw, and the first bearing and the second bearing are self-aligning bearings to allow the screw to move radially in the sliding process;

the boarding bridge lifting device also comprises a power unit, wherein the power unit comprises an oil tank, a filter, a hydraulic pump, a one-way valve and a second overflow valve; when the hydraulic pump works, hydraulic oil in the oil tank can be pressed into the upper oil cavity of the hydraulic cylinder, oil in the lower oil cavity flows back into the oil tank, and the piston descends to the lowest position in the cylinder body.

2. The boarding bridge lifting device according to claim 1, wherein two hydraulic cylinders are symmetrically arranged outside each outer sleeve, and when the solenoid valve is opened, the cylinders of the two hydraulic cylinders are synchronously lowered to the second position.

3. The boarding bridge lifting device of claim 2, wherein a first baffle is protruded on the inner periphery of the transition sleeve, and a second baffle is protruded on the outer periphery of the upper end of the outer sleeve; in the process that the cylinder body descends from the first position, the second baffle descends to the first baffle along with the outer sleeve and is stopped by the first baffle, and the cylinder body is located at the second position at the moment.

4. The boarding bridge lifting device according to claim 3, wherein a buffer block is provided on a lower surface of the second baffle, and the buffer block is in direct contact with the first baffle when the second baffle is lowered onto the first baffle along with the outer sleeve.

5. The boarding bridge lifting device according to claim 3, wherein a stopper is provided at a lower end of the inner tube, and when the outer tube is lowered to be stopped by the stopper, the cylinder is in the third position.

6. The boarding bridge lifting device of claim 5, wherein when the cylinder is at the third position, the output shaft of the motor continues to rotate in the first direction so that the screw rod descends, and the piston can continue to descend to the lowest position in the cylinder.

7. The boarding bridge lifting device according to claim 6, wherein the solenoid valve is a one-way solenoid valve, when the solenoid valve is closed, oil in the cylinder body is allowed to flow from the lower oil chamber to the upper oil chamber, and oil in the upper oil chamber cannot flow to the lower oil chamber; when the electromagnetic valve is opened, oil in the cylinder body is allowed to flow between the upper oil chamber and the lower oil chamber.

8. The boarding bridge lifting device according to claim 7, wherein when the cylinder is at the third position and the piston is lowered to the lowest position in the cylinder, the solenoid valve is closed, the output shaft of the motor rotates in the second direction to raise the screw, the piston is raised therewith, and the cylinder and the outer sleeve are raised to return to the first position, wherein the second direction is opposite to the first direction.

9. The boarding bridge lifting device of claim 3, wherein the quick drop mechanism further comprises a hinge holder including a first hinge portion and a second hinge portion, one end of the first hinge portion is hinged to the transition sleeve at a first hinge point, one end of the second hinge portion is hinged to the outer sleeve at a second hinge point, the other end of the first hinge portion is hinged to the other end of the second hinge portion, and the first hinge point is parallel to the axis of the second hinge point.

10. The boarding bridge lifting device according to claim 9, wherein the inner sleeve, the outer sleeve and the transition sleeve are polygonal with the same shape, and one hinge holder is provided on each side of the outer sleeve and the transition sleeve.

11. The boarding bridge lifting device according to claim 1, wherein the inner sleeve and the outer sleeve are provided with sliders, and the sliders are located between the inner sleeve and the outer sleeve.

12. The boarding bridge lifting device of claim 1, wherein the control mechanism further comprises a throttle valve located on the first oil path to control the flow rate of oil.

13. The boarding bridge lifting device according to claim 12, wherein the control mechanism further comprises a first relief valve provided on a second oil passage connected in parallel with the first oil passage, the first relief valve allowing the oil in the upper oil chamber to flow into the lower oil chamber via the second oil passage when opened.

14. The boarding bridge lifting device according to claim 13, wherein the control mechanism further comprises an accumulator for supplementing or absorbing hydraulic oil in the lower oil chamber.

15. The boarding bridge lifting device of claim 2, wherein the control mechanism further comprises a travel switch disposed on an outer wall of the transition sleeve; when the cylinder body is at the first position, the travel switch is not triggered; when the piston of the hydraulic cylinder is not at the lowest position of the cylinder body, the travel switch is triggered, and therefore the boarding bridge channel is judged to be in a quick descending completion state.