Crank arm lifting mechanism and overhead working truck

Abstract

The utility model provides a crank arm lifting mechanism and an overhead working truck. The crank arm lifting mechanism comprises a lower folding arm, a lower pull rod, a lower connecting seat, a synchronous pull rod, an upper folding arm, an upper pull rod and an upper connecting seat; the lower folding arm is respectively hinged with the lower connecting seat and the lower connecting seat, the lower pull rod and the lower folding arm are arranged in parallel up and down, and a lifting oil cylinder is connected between the lower folding arm and the lower connecting seat; the upper pull rod is respectively hinged with the lower connecting seat and the upper connecting seat; one end of the upper folding arm is connected to the seventh pin shaft, the other end of the upper folding arm is hinged to the upper connecting seat through a twelfth pin shaft, and the upper folding arm and the upper pull rod are arranged in parallel up and down; and the synchronous pull rod is respectively hinged with the upper folding arm and the lower folding arm. According to the utility model, the lifting mechanism can be arranged in the middle relative to the rotary table, so that the lateral rigidity and torsion resistance of the whole vehicle are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of aerial work platforms, in particular to a crank arm lifting mechanism and an aerial work vehicle. Background Art

[0002] Articulated boom aerial work platforms have a greater ability to cross obstacles and are better able to adapt to narrow and crowded work sites. They are widely used in construction, logistics and warehousing, equipment installation, fire rescue, venue maintenance, electricity, and landscaping.

[0003] Existing articulated boom work platforms, such as the one disclosed in Patent Publication No. CN111086961A, feature an articulated boom lift structure. The third boom is positioned to one side, rather than centrally. This can lead to significant off-center loading, poor lateral stiffness, and significant boom wobbling. The boom structure's poor ability to resist off-center loading can easily cause lateral deflection and significant wobbling when working on potholes. This not only compromises the operator's experience with the equipment but also creates the risk of equipment rollover.

[0004] For example, the novel crank arm device disclosed in existing patent publication number CN114671381A focuses on how to improve the stiffness of the crank arm device while increasing the lifting height and load capacity. However, it does not consider the lateral stiffness of the boom when the vehicle is on a lateral slope. When the crank arm is lowered into position, its first and second folding arms form a cross structure, with the first folding arm located between the two main beams of the second folding arm. Therefore, the two main beams of the second folding arm can only be designed as a cantilever beam structure, and the two main beams cannot be connected as a whole. Otherwise, interference problems will occur. However, this cantilever beam structure leads to insufficient lateral stiffness. Therefore, when the vehicle is operating on a road with a lateral slope, the lateral stiffness is relatively weak. Utility Model Content

[0005] The purpose of the utility model is to provide a crank arm lifting mechanism and an aerial work vehicle, so as to improve the lateral rigidity of the whole vehicle.

[0006] The technical solution of the utility model is: a crank arm lifting mechanism, comprising a lower folding arm, a lower pull rod, a lower connecting seat, a synchronous pull rod, an upper folding arm, an upper pull rod and an upper connecting seat; one end of the lower folding arm is hinged on the lower end of the lower connecting seat through a ninth pin, and one end of the lower pull rod is hinged on the upper end of the lower connecting seat through a seventh pin, and the lower pull rod and the lower folding arm are arranged parallel to each other up and down, and a lifting cylinder is connected between the lower folding arm and the lower connecting seat; one end of the upper pull rod is hinged on the lower connecting seat through an eighth pin, and the other end of the upper pull rod is hinged on the upper connecting seat through an eleventh pin; one end of the upper folding arm is hinged to the seventh pin, and the other end of the upper folding arm is hinged to the upper connecting seat through a twelfth pin, and the upper folding arm and the upper pull rod are arranged parallel to each other up and down; one end of the synchronous pull rod is hinged to the upper folding arm through the fourth pin, and the other end of the synchronous pull rod is hinged to the lower folding arm through the third pin.

[0007] In the above scheme, the crank arm lifting mechanism is designed as two parallel structures, one is the upper folding arm and the upper pull rod, and the other is the lower pull rod and the lower folding arm. Compared with the cross structure, the parallel structure can improve the lateral stiffness and torsional resistance of the entire vehicle.

[0008] Preferably, the lower folding arm includes two first main beams arranged at intervals, at least one first rectangular tube connected between the two first main beams, a first hinge hole is provided at one end of the first main beam, a first side vertical plate is provided at the other end of the first main beam, the two first hinge holes are connected by a first shaft sleeve, a second hinge hole for installing the third pin shaft and a third shaft sleeve for fitting the ninth pin shaft are provided on the first side vertical plate; a fifth pin shaft is installed between the two first main beams, and one end of the lifting cylinder is connected to the fifth pin shaft.

[0009] Preferably, a first reinforcing plate and a second reinforcing plate are provided on the side surface of the first main beam, the first reinforcing plate is arranged close to the first hinge hole, and the second reinforcing plate is arranged close to the fifth pin shaft.

[0010] Preferably, two first side vertical plates are provided on the inner and outer surfaces of the first main beam, and the third sleeve is connected between the two first side vertical plates on the same first main beam.

[0011] Preferably, the lower connecting seat includes two first main vertical plates arranged at intervals, two first neutral plates located between the two first main vertical plates, multiple first connecting plates connected between the two first neutral plates, a circular tube connected between the first neutral plate and the first main vertical plates, and two box-type plates respectively arranged on the outside of the two first main vertical plates. The seventh pin shaft is connected to the first main vertical plate, the first neutral plate and the box-type plate at one end of the lower connecting seat, the ninth pin shaft is connected to the first main vertical plate and the first neutral plate at the other end of the lower connecting seat, the eighth pin shaft is connected between the two first main vertical plates, a sixth pin shaft is connected between the two first neutral plates, and one end of the lifting cylinder is connected to the sixth pin shaft.

[0012] Preferably, the box-type panel includes two spaced-apart side panels and a sealing plate connected between the two side panels, the seventh pin shaft passes through and is connected to the side panels, and one of the side panels is fitted and fixed to the first main vertical panel.

[0013] Preferably, the upper folding arm includes two second main beams arranged at intervals, at least one second rectangular tube connected between the two second main beams, one end of the second main beam is provided with an eighth shaft sleeve for fitting the twelfth pin shaft, and the other end of the second main beam is provided with a ninth shaft sleeve for fitting the seventh pin shaft and a third hinge hole for fitting the fourth pin shaft.

[0014] Preferably, the upper pull rod includes two third main beams arranged at intervals, at least one third rectangular tube connected between the two third main beams, one end of the third main beam is provided with a tenth shaft sleeve for fitting the eleventh pin shaft, and the other end of the third main beam is provided with an eleventh shaft sleeve for fitting the eighth pin shaft.

[0015] Preferably, the upper connecting seat includes two second main vertical panels arranged at intervals, two third neutral panels located between the two second main vertical panels, a second connecting plate connected between the two third neutral panels, a fourth rectangular tube connected between the second main vertical panels and the third neutral panel, and a fifth rectangular tube connected between the two second main vertical panels; one end of the two second main vertical panels is provided with the tenth pin shaft, the other end of the two second main vertical panels is provided with the eleventh pin shaft, the twelfth pin shaft is connected between the two second main vertical panels, one end of the two third neutral panels is connected to the fifth rectangular tube, and the other end of the two third neutral panels is connected with a thirteenth pin shaft.

[0016] The utility model also provides an aerial work vehicle, comprising a chassis, a turntable rotatably arranged on the chassis, a main arm and the above-mentioned crank arm lifting mechanism, the lower folding arm in the crank arm lifting mechanism is hinged to the turntable through a first pin shaft, the lower pull rod is hinged to the turntable through a second pin shaft, the main arm is hinged to the upper connecting seat through a tenth pin shaft, and a variable amplitude oil cylinder is connected between the upper connecting seat and the main arm.

[0017] Compared with the related art, the beneficial effects of the present invention are:

[0018] First, the utility model designs the crank arm lifting mechanism into two parallel structures: an upper folding arm and an upper pull rod, and a lower pull rod and a lower folding arm. Compared with a cross structure, the parallel structure can improve the lateral rigidity and torsional resistance of the entire vehicle. When the vehicle is operating on a road with a lateral slope, the arm deformation is small, and the operation is more stable and safer.

[0019] Second, the lower folding arm adopts a stable frame structure formed by two first main beams and a first rectangular tube, while the upper folding arm adopts a stable frame structure formed by two second main beams and a second rectangular tube. This improves the lateral rigidity of the lower folding arm and the upper folding arm respectively, allowing the turntable and lower folding arm to withstand eccentric loads, further improving the lateral rigidity of the entire vehicle when operating on lateral slopes.

[0020] 3. The lower connecting seat adopts a structural design of the first main vertical plate, the first middle vertical plate and the box-type plate. The box-type plate is located on the outside of the first main vertical plate, thereby increasing the lateral rigidity of the upper connecting seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the three-dimensional structure of the crank arm lifting mechanism provided by the utility model;

[0022] Figure 2 This is a front view structural diagram of the connection between the crank arm lifting mechanism and the main arm provided by the utility model;

[0023] Figure 3 Schematic diagram of the structure of the lower folding arm;

[0024] Figure 4 Schematic diagram of the structure of the lower connecting seat;

[0025] Figure 5 Schematic diagram of the structure of the upper folding arm;

[0026] Figure 6 Schematic diagram of the structure of the upper pull rod;

[0027] Figure 7 Schematic diagram of the structure of the upper connecting seat;

[0028] Figure 8 A schematic diagram of the three-dimensional structure of the aerial work vehicle provided by the utility model;

[0029] Figure 9 This is a front view structural diagram of the aerial work vehicle provided by the utility model;

[0030] Figure 10 Schematic diagram of automatic leveling cylinder assembly Figure 1 ;

[0031] Figure 11 Schematic diagram of automatic leveling cylinder assembly Figure 2 . DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention may be combined unless they conflict. For ease of description, the words "upper," "lower," "left," and "right" appear below merely to indicate the directions of upper, lower, left, and right in the accompanying drawings and do not limit the structure.

[0033] like Figure 1 As shown, the crank arm lifting mechanism 3 provided in this embodiment includes a lower folding arm 100, a lower pull rod 200, a lower connecting seat 300, a synchronous pull rod 400, an upper folding arm 500, an upper pull rod 600, an upper connecting seat 700 and a lifting cylinder 800.

[0034] One end of the lower folding arm 100 is hinged to the lower end of the lower connecting base 300 via a ninth pin 3800. One end of the lower tie rod 200 is hinged to the upper end of the lower connecting base 300 via a seventh pin 3500. The lower tie rod 200 and the lower folding arm 100 are arranged vertically parallel to each other, and a lifting cylinder 800 is connected between the lower folding arm 100 and the lower connecting base 300. One end of the upper tie rod 600 is hinged to the lower connecting base 300 via an eighth pin 3700, and the other end of the upper tie rod 600 is hinged to the upper connecting base 700 via an eleventh pin 7500. One end of the upper folding arm 500 is connected to the seventh pin 3500, and the other end of the upper folding arm 500 is hinged to the upper connecting base 700 via a twelfth pin 7600. The upper folding arm 500 and the upper tie rod 600 are arranged vertically parallel to each other. One end of the synchronization rod 400 is hinged to the upper folding arm 500 via a fourth pin 5800. The other end of the synchronization rod 400 is hinged to the lower folding arm 100 via a third pin 1800.

[0035] like Figure 3 As shown, the lower folding arm 100 includes two first main beams 110 spaced apart and three first rectangular tubes 170 connected between the two first main beams 110. The three first rectangular tubes 170 are spaced apart in the length direction of the first main beam 110. A first hinge hole 121 is provided at one end of the first main beam 110, and a first side vertical plate 140 is provided at the other end of the first main beam 110. The two first hinge holes 121 are connected through a first shaft sleeve 120. The first shaft sleeve 120 is used to install a first pin shaft 2100, which is hinged to the turntable 2 (as shown in FIG. Figure 9 shown).

[0036] Two first side uprights 140 are provided on the inner and outer surfaces of the first main beam 110. Each first side upright 140 is triangular in shape, with one corner on its base connected to the first main beam 110. A third bushing 130 is located at the other corner of the base, and a second hinge hole 141 is located at the top corner of the triangle. The third bushing 130 is connected between two first side uprights 140 on the same first main beam 110. A second hinge hole 141 is formed on each first side upright 140, into which a bushing is inserted. A third pin 1800 is installed between the bushings in the two second hinge holes 141 on the same first main beam 110. The third bushing 130 is used to attach the ninth pin 3800. A plate is also connected between the lower surfaces of the two first main beams 110 to enhance the stability of the overall frame. A fifth pin 1600 is installed between the two first main beams 110, and one end of the lifting cylinder 800 is connected to the fifth pin 1600.

[0037] like Figure 4 As shown, the lower connecting base 300 includes two first main vertical panels 310 spaced apart, two first neutral panels 320 located between the two first main vertical panels 310, a plurality of first connecting panels 321 connected between the two first neutral panels 320, a circular tube 330 connected between the first neutral panel 320 and the first main vertical panels 310, and two box-shaped panels 340 disposed on the outsides of the two first main vertical panels 310. The first main vertical panels 310 and the first neutral panel 320 are each provided with three hinge points.

[0038] The box-shaped plate 340 includes two spaced-apart side plates 3401 and a sealing plate 3402 connected between the two side plates 3401. One of the side plates 3401 is fixedly attached to the first main vertical plate 310.

[0039] The seventh pin 3500, at one end of the lower connecting base 300, penetrates and connects to the first main vertical plate 310, the first neutral plate 320, and the side plate 3401 of the box-type plate 340. The ninth pin 3800, at the other end of the lower connecting base 300, connects to the first main vertical plate 310 and the first neutral plate 320. The eighth pin 3700 is connected between the two first main vertical plates 310. A sixth pin 360 is connected between the two first neutral plates 320. The other end of the lifting cylinder 800 is connected to the sixth pin 360.

[0040] A fourth shaft sleeve 311 is mounted between the ninth pin 3800 and the first main vertical plate 310 and the first neutral plate 320. A fifth shaft sleeve 313 is mounted between the eighth pin 3700 and the first main vertical plate 310. A seventh shaft sleeve 344 is mounted between the sixth pin 3600 and the first neutral plate 320. A sixth shaft sleeve 343 is mounted between the seventh pin 3500 and the box-type plate 340, between the seventh pin 3500 and the first main vertical plate 310, and between the seventh pin 3500 and the first neutral plate 320.

[0041] A third reinforcing plate 312 is fixed to the side surface of the first main vertical plate 310 . The third reinforcing plate 312 is disposed close to the circular tube 330 and the fifth shaft sleeve 313 .

[0042] like Figure 5 As shown, the upper folding arm 500 includes two spaced-apart second main beams 510 and two second rectangular tubes 550 connected between the two second main beams 510. The two second rectangular tubes 550 are spaced apart along the length of the second main beam 510. An eighth sleeve 520 for receiving the twelfth pin 7600 is provided at one end of the second main beam 510, and a second side plate 540 is provided at the other end of the second main beam 510. Two second side plates 540 are attached to the inner and outer surfaces of the second main beam 510. A fourth pin 5800 is connected between the two second side plates 540 on the same second main beam 510. Each second side plate 540 is provided with a ninth sleeve 530 for receiving the seventh pin 3500 and a third hinge hole 541 for receiving the fourth pin 5800. A fourth reinforcing plate 521 is provided on the side surface of the second main beam 510, located near the eighth sleeve 520.

[0043] like Figure 6 As shown, the upper tie rod 600 includes two spaced-apart third main beams 610 and two third rectangular tubes 640 connected between the two third main beams 610. The two third rectangular tubes 640 are spaced apart along the length of the third main beam 610. A tenth sleeve 620, which receives the eleventh pin 7500, is provided at one end of the third main beam 610. An eleventh sleeve 630, which receives the eighth pin 3700, is provided at the other end of the third main beam 610. A fifth reinforcing plate 621 is provided on the side surface of the third main beam 610, positioned adjacent to the tenth sleeve 620 and the eleventh sleeve 630, respectively.

[0044] like Figure 7As shown, the upper connecting base 700 includes two spaced-apart second main vertical plates 710, two third neutral plates 740 located between the two second main vertical plates 710, a second connecting plate 742 connected between the two third neutral plates 740, a fourth rectangular tube 744 connected between the second main vertical plates 710 and the third neutral plates 740, and a fifth rectangular tube 745 connected between the two second main vertical plates 710. One end of the two third neutral plates 740 is connected to the fifth rectangular tube 745, and a thirteenth pin 7800 is connected between the other ends of the two third neutral plates 740.

[0045] The tenth pin 7700 is provided at one end of the two second main vertical panels 710, the eleventh pin 7500 is provided at the other end of the two second main vertical panels 710, and the twelfth pin 7600 is connected between the two second main vertical panels 710. The second main vertical panels 710 are provided with a fifth hinge hole 713 for mounting the twelfth pin 7600 and a sixth hinge hole 712 for mounting the eleventh pin 7500.

[0046] Two second neutral panels 720 are further disposed within the inner portion of the second main vertical panels 710. Multiple second closing panels 722 are connected between the second neutral panels 720 and the second main vertical panels 710. The second neutral panels 720 define fourth hinge holes 726 for mounting the tenth pin 7700. A third connecting panel 730 is connected between the second main vertical panels 710. The second closing panels 722, the second neutral panels 720, the second main vertical panels 710, and the third connecting panels 730 form a box-shaped structure.

[0047] The second main vertical panel 710 is provided with a process hole 715, which is located near the tenth pin 7700. The tenth pin 7700 extends through and connects the second main vertical panel 710 and the second intermediate panel 720. A sixth reinforcement plate 711 is fixed to the outer surface of the second main vertical panel 710, covering the tenth pin 7700, the process hole 715, the fifth hinge hole 713, and the sixth hinge hole 712.

[0048] The seventh pin shaft 3500 , the ninth pin shaft 3800 and the eighth pin shaft 3700 are designed as through shafts, which hinge the components together and can greatly enhance the lateral rigidity of the lower connecting seat 300 .

[0049] The eleventh pin 7500 and the twelfth pin 7600 are designed as through-axes, which articulate the components together and can greatly enhance the lateral rigidity of the upper connecting seat 700. The fifteenth pin 5200 is mounted on the second main vertical plate 710.

[0050] like Figure 8 、 Figure 9As shown, the utility model also provides an aerial work vehicle, including a chassis 1, a turntable 2, an active leveling cylinder 4, a main arm 5, a luffing cylinder 6, a passive leveling cylinder 7, a flying arm 8 and a working platform 9.

[0051] The lower folding arm 100 is hinged to the turntable 2 via a first pin 2100, the lower pull rod 200 is hinged to the turntable 2 via a second pin 2200, and the main arm 5 is hinged to the upper connecting base 700 via a tenth pin 7700. The first pin 2100 is an integral through-shaft, enabling the turntable 2 and lower folding arm 100 to withstand deflection as a whole, thereby improving lateral stiffness during operation on lateral slopes.

[0052] One end of the luffing cylinder 6 is hinged to the thirteenth pin 7800, and the other end of the luffing cylinder 6 is hinged to one end of the main boom 5. The other end of the main boom 5 is hinged to one end of the fly boom 8, and a passive leveling cylinder 7 is hinged between the main boom 5 and the fly boom 8. The other end of the fly boom 8 is mounted on the work platform 9.

[0053] like Figure 10 、 Figure 11 As shown, the upper connecting seat 700 is provided with a process hole 715, and a fourteenth pin 5100 is provided in the main arm 5. The diameter of the process hole 715 is larger than the diameter of the fourteenth pin 5100. During assembly, the active leveling cylinder 4 is hinged to the upper connecting seat 700 via the fifteenth pin 5200. After the main arm 5 is connected to the upper connecting seat 700 via the tenth pin 7700, the upper hinge point of the active leveling cylinder 4, the process hole 715, and the leveling hinge hole on the main arm 5 are coaxially aligned. The fortieth pin 5100 is then inserted through the process hole 715 until it passes through the leveling hinge hole on the main arm 5 and the upper hinge point of the active leveling cylinder 4, thereby hingedly fixing the active leveling cylinder 4 to the main arm 5. The provision of the process hole 715 facilitates the assembly of the active leveling cylinder 4.

[0054] like Figure 9 As shown, the turntable 2, the lower folding arm 100, the lower connecting seat 300 and the lower pull rod 200 form a parallelogram structure I. The lower connecting seat 300, the upper folding arm 500, the upper pull rod 600 and the upper connecting seat 700 form a parallelogram structure II.

[0055] The working principle of the crank arm lifting mechanism 3 is as follows: when the lifting cylinder 800 extends or contracts, it drives the parallelogram structure I to rise or fall. At the same time, under the action of the synchronization rod 400, the parallelogram structure II is synchronously driven to rise or fall.

[0056] When the lifting cylinder 800 is shortened to its minimum length and the lifting mechanism 3 is lowered into place, the lifting mechanism 3 is in the stowed state. At this time, the lower folding arm 100, the upper folding arm 500, the upper rod 600, and the lower rod 200 are all parallel to each other. The upper folding arm 500 and the lower folding arm 100 do not cross each other during the entire movement process.

[0057] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A crank arm lifting mechanism, characterized in that: The utility model comprises a lower folding arm (100), a lower pull rod (200), a lower connecting seat (300), a synchronous pull rod (400), an upper folding arm (500), an upper pull rod (600) and an upper connecting seat (700); one end of the lower folding arm (100) is hinged to the lower end of the lower connecting seat (300) through a ninth pin (3800), one end of the lower pull rod (200) is hinged to the upper end of the lower connecting seat (300) through a seventh pin (3500), the lower pull rod (200) and the lower folding arm (100) are arranged parallel to each other, and a lifting cylinder (800) is connected between the lower folding arm (100) and the lower connecting seat (300); one end of the upper pull rod (600) is hinged to the upper end of the lower connecting seat (300) through an eighth pin (3 The upper pull rod (600) is hinged to the lower connecting seat (300), and the other end of the upper pull rod (600) is hinged to the upper connecting seat (700) through the eleventh pin shaft (7500); one end of the upper folding arm (500) is hinged to the seventh pin shaft (3500), and the other end of the upper folding arm (500) is hinged to the upper connecting seat (700) through the twelfth pin shaft (7600), and the upper folding arm (500) and the upper pull rod (600) are arranged parallel to each other; one end of the synchronous pull rod (400) is hinged to the upper folding arm (500) through the fourth pin shaft (5800), and the other end of the synchronous pull rod (400) is hinged to the lower folding arm (100) through the third pin shaft (1800).

2. The crank arm lifting mechanism according to claim 1, characterized in that: The lower folding arm (100) includes two first main beams (110) arranged at intervals, and at least one first rectangular tube (170) connected between the two first main beams (110). One end of the first main beam (110) is provided with a first hinge hole (121), and the other end of the first main beam (110) is provided with a first side vertical plate (140). The two first hinge holes (121) are connected through a first shaft sleeve (120). The first side vertical plate (140) is provided with a second hinge hole (141) for installing the third pin shaft (1800) and a third shaft sleeve (130) for sleeve-mounting the ninth pin shaft (3800). A fifth pin shaft (1600) is installed between the two first main beams (110), and one end of the lifting cylinder (800) is connected to the fifth pin shaft (1600).

3. The crank arm lifting mechanism according to claim 2, characterized in that: A first reinforcing plate (123) and a second reinforcing plate (153) are provided on the side surface of the first main beam (110), wherein the first reinforcing plate (123) is arranged close to the first hinge hole (121), and the second reinforcing plate (153) is arranged close to the fifth pin shaft (1600).

4. The crank arm lifting mechanism according to claim 2, characterized in that: Two first side upright plates (140) are provided on the inner and outer surfaces of the first main beam (110), and the third shaft sleeve (130) is connected between the two first side upright plates (140) on the same first main beam (110).

5. The crank arm lifting mechanism according to claim 1, characterized in that: The lower connecting seat (300) comprises two first main vertical plates (310) spaced apart, two first neutral plates (320) located between the two first main vertical plates (310), a plurality of first connecting plates (321) connected between the two first neutral plates (320), a circular tube (330) connected between the first neutral plate (320) and the first main vertical plates (310), and two box-shaped plates (340) respectively arranged on the outside of the two first main vertical plates (310). The seventh pin shaft (3500) is located on the lower connecting seat (300). One end of the ninth pin (3800) is connected to the first main vertical plate (310), the first neutral plate (320) and the box-type plate (340); the other end of the ninth pin (3800) is connected to the first main vertical plate (310) and the first neutral plate (320) at the lower connecting seat (300); the eighth pin (3700) is connected between the two first main vertical plates (310); a sixth pin (360) is connected between the two first neutral plates (320); and one end of the lifting cylinder (800) is connected to the sixth pin (360).

6. The crank arm lifting mechanism according to claim 5, characterized in that: The box-shaped plate (340) includes two spaced-apart side plates (3401) and a sealing plate (3402) connected between the two side plates (3401). The seventh pin (3500) is connected through the side plates (3401). One of the side plates (3401) is fixedly attached to the first main vertical plate (310).

7. The crank arm lifting mechanism according to claim 1, characterized in that: The upper folding arm (500) comprises two second main beams (510) spaced apart, and at least one second rectangular tube (550) connected between the two second main beams (510). One end of the second main beam (510) is provided with an eighth shaft sleeve (520) for fitting a twelfth pin shaft (7600). The other end of the second main beam (510) is provided with a ninth shaft sleeve (530) for fitting a seventh pin shaft (3500) and a third hinge hole (541) for fitting a fourth pin shaft (5800).

8. The crank arm lifting mechanism according to claim 1, characterized in that: The upper pull rod (600) includes two third main beams (610) arranged at intervals, and at least one third rectangular tube (640) connected between the two third main beams (610). One end of the third main beam (610) is provided for fitting a tenth shaft sleeve (620) of an eleventh pin shaft (7500), and the other end of the third main beam (610) is provided for fitting an eleventh shaft sleeve (630) of an eighth pin shaft (3700).

9. The crank arm lifting mechanism according to claim 1, characterized in that: The upper connecting seat (700) comprises two second main vertical plates (710) arranged at intervals, two third neutral plates (740) located between the two second main vertical plates (710), a second connecting plate (742) connected between the two third neutral plates (740), a fourth rectangular tube (744) connected between the second main vertical plates (710) and the third neutral plate (740), and a fifth rectangular tube (745) connected between the two second main vertical plates (710); one end of the two second main vertical plates (710) is provided with a tenth pin (7700), the other end of the two second main vertical plates (710) is provided with the eleventh pin (7500), the twelfth pin (7600) is connected between the two second main vertical plates (710), one end of the two third neutral plates (740) is connected to the fifth rectangular tube (745), and the other end of the two third neutral plates (740) is connected with a thirteenth pin (7800).

10. An aerial work vehicle comprising a chassis (1), a turntable (2) rotatably mounted on the chassis (1), and a main arm (5), characterized in that: It also includes a crank arm lifting mechanism as described in any one of claims 1 to 9, wherein the lower folding arm (100) in the crank arm lifting mechanism is hinged to the turntable (2) through a first pin (2100), the lower pull rod (200) is hinged to the turntable (2) through a second pin (2200), the main arm (5) is hinged to the upper connecting seat (700) through a tenth pin (7700), and a variable amplitude cylinder (6) is connected between the upper connecting seat (700) and the main arm (5).

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