Interlocking multi-stage cylinder and boom for aerial work platform vehicle using same

Abstract

The objective of the present invention is to provide an interlocking multi-stage cylinder in which multiple cylinders can be simultaneously driven, and a boom for an aerial work platform vehicle using same. Boom rods of a boom for an aerial work platform vehicle equipped with the interlocking multi-stage cylinder according to the present invention can be smoothly moved. According to the present invention, operation balance and stability of each of the boom rods may be increased, fatigue applied to each of the boom rods may be reduced, accordingly, impact caused to a worker may be reduced, anxiety of the worker may be reduced, the risk of accidents may be lowered, and the entire movement time may be shortened when the cylinder rods move at the same time so that the boom extends and retracts. Therefore, there is an effect that the speed of the process of adjusting the length of the boom can be increased.

Description

Linked multi-stage cylinder and boom for aerial work vehicle using the same

[0001] The present invention relates to a linked multi-stage cylinder and a boom for an aerial work vehicle using the same.

[0002] In high-altitude ladder trucks (high-altitude work vehicles), a multi-stage boom is used so that workers can ride the work platform to move to the desired high location and work.

[0003] To operate a multi-stage boom, wires were traditionally used. That is, the length of the boom was increased or decreased by pulling and extending the wires.

[0004] In this case, because the wire is elastic, it can stretch or become damaged over time, reducing its accuracy. Furthermore, due to the wire's elasticity, the boom may not respond immediately when extended or retracted, resulting in a delayed initial response. Furthermore, the wire has poor durability. Furthermore, the wire can generate irregular shocks and vibrations, exposing workers to the risk of safety accidents.

[0005] Recently, attempts have been made to use hydraulic cylinders instead of wire-driven ones. However, because these methods combine simple single-stage cylinders with conventional wire-driven ones, the drive components are not standardized. Consequently, rattling shocks and vibrations occur at the boundary between cylinder operation and wire operation. This shock and vibration is transmitted to workers, causing them to feel uneasy and exposing them to the risk of safety accidents.

[0006] In addition, even when combining only multi-stage cylinders, there is a disadvantage in that the device structure is complex and large, taking up a lot of space, because it is a method of simply combining a large number of simple cylinders.

[0007] Furthermore, conventional multi-stage cylinders utilize a sequential movement method, whereby one cylinder begins its movement and, once its movement is fully completed, moves on to the next cylinder. However, when cylinders move sequentially, the operating time increases by the amount of time it takes for the sequential movement, leading to a problem in that the operating process steps become longer.

[0008] The purpose of the present invention, proposed to solve the above-described problem, is to provide a linked multi-stage cylinder capable of simultaneously driving a plurality of cylinders and a boom for an aerial work vehicle using the same.

[0009] In order to achieve the above-described technical problem, a linked multi-stage cylinder according to an embodiment of the present invention comprises: a first cylinder rod including a first lower plate and a first extension portion extending upward from the first lower plate; a second cylinder rod inserted into an internal space of the first extension portion through an upper end of the first extension portion and reciprocating in an up-and-down direction of the first extension portion; a third cylinder rod inserted into an internal space of the second cylinder rod through an upper end of the second cylinder rod and reciprocating in an up-and-down direction of the second cylinder rod; an extraction portion connected to the internal space of the first extension portion through the first lower plate and into which extraction hydraulic oil is injected; And it includes an inlet portion that extends from the first lower plate to the inner space of the third cylinder rod through the second cylinder rod and into which hydraulic oil for inlet is injected, and among the inner spaces of the first extension portion, a first inner space between the first lower plate and the lower end of the second cylinder rod is filled with first hydraulic oil, and among the inner spaces of the first extension portion, a second inner space between the outer circumference of the upper end of the second cylinder rod and the inner circumference of the first extension portion and a second inner space between the inner circumference of the second cylinder rod and the lower end of the third cylinder rod are filled with second hydraulic oil, and the second inner space and the second inner space are in communication with each other, and among the inner spaces of the second cylinder rod, a third inner space between the outer circumference of the upper end of the third cylinder rod and the inner circumference of the second cylinder rod and a third inner space which is an inner space of the third cylinder rod are filled with third hydraulic oil, and the third inner space and the third inner space are in communication with each other.

[0010] According to an embodiment of the present invention, when hydraulic oil for withdrawal is injected into the first internal space through the withdrawal portion, the second cylinder rod can be moved upward from the lower end of the first cylinder rod, and when the second cylinder rod is moved, the third cylinder rod can be moved upward from the lower end of the second cylinder rod.

[0011] According to an embodiment of the present invention, the second cylinder rod includes a second lower plate that moves along the inner surface of the first extension portion; and a second extension portion that extends from the upper surface of the second lower plate toward the upper side of the second cylinder rod, and a second through hole that connects the second a internal space and the second b internal space may be formed in the second extension portion.

[0012] According to an embodiment of the present invention, the third cylinder rod includes a third lower plate that moves along the inner surface of the second extension portion; and a third extension portion that extends from the upper surface of the third lower plate toward the upper side of the third cylinder rod, and a third through hole that connects the 3a internal space and the 3b internal space may be formed in the third extension portion.

[0013] According to an embodiment of the present invention, the inlet portion extends through the first lower plate, the second lower plate, and the third lower plate to the 3b internal space, and the hydraulic oil for inlet can be injected into the 3b internal space through the inlet portion.

[0014] According to an embodiment of the present invention, when the hydraulic oil for withdrawal flows into the first internal space through the withdrawal portion, the second lower plate moves toward the upper end of the first extension portion along the inner surface of the first extension portion by the hydraulic oil for withdrawal, and when the second lower plate moves toward the upper end of the first extension portion, the second hydraulic oil in the 2a internal space flows into the 2b internal space through the second through hole, and the third lower plate can move toward the upper end of the second extension portion along the inner surface of the second extension portion by the second hydraulic oil flowing into the 2b internal space.

[0015] According to an embodiment of the present invention, when the hydraulic oil for introduction is introduced into the 3b internal space through the introduction portion, the third hydraulic oil is introduced into the 3a internal space through the third through hole, and the upper surface of the third lower plate is pressed by the third hydraulic oil introduced into the 3a internal space, so that the third lower plate moves along the inner surface of the second extension portion toward the lower side of the second extension portion, and when the third lower plate moves toward the lower side of the second extension portion, the second hydraulic oil in the 2b internal space is introduced into the 2a internal space through the second through hole, and the upper surface of the second lower plate is pressed by the second hydraulic oil introduced into the 2a internal space, so that the second lower plate can move along the inner surface of the first extension portion toward the lower side of the first extension portion.

[0016] A boom for an aerial work vehicle according to an embodiment of the present invention includes a first boom rod, a second boom rod, and a third boom rod, wherein the first boom rod can be connected to the first cylinder rod, the second boom rod can be connected to the second cylinder rod, and the third boom rod can be connected to the third cylinder rod.

[0017] Since the cylinder rods constituting the linked multi-stage cylinder according to the present invention can be driven continuously, the boom rods of the boom for an aerial work vehicle equipped with the linked multi-stage cylinder according to the present invention can be moved smoothly.

[0018] That is, according to the present invention, the operational balance and stability of each boom rod are improved. In addition, fatigue applied to each boom rod is reduced, and thus the shock applied to the worker is reduced. Therefore, the worker's anxiety can be reduced, and the risk of safety accidents can be lowered.

[0019] Furthermore, according to the present invention, each cylinder rod can move simultaneously, reducing the overall travel time during withdrawal and retraction. Consequently, the process of adjusting the boom length can be accelerated. Consequently, work using the boom can proceed more quickly.

[0020] Figure 1 is an exemplary drawing showing an aerial work vehicle equipped with a boom for an aerial work vehicle according to the present invention.

[0021] Figure 2 is an exemplary diagram showing a boom for an aerial work vehicle according to the present invention.

[0022] Figure 3 is an exemplary diagram showing a method for changing the length of a boom for an aerial work vehicle illustrated in Figure 2.

[0023] Figure 4 is an exemplary drawing schematically showing a cross-section of a linked multi-stage cylinder according to the present invention.

[0024] Fig. 5 is an exemplary diagram illustrating a method for increasing the length of the linked multi-stage cylinder illustrated in Fig. 4.

[0025] Fig. 6 is an exemplary diagram illustrating a method for reducing the length of the linked multi-stage cylinder illustrated in Fig. 4.

[0026] Figure 7 is an exemplary drawing showing the appearance of a linked multi-stage cylinder according to the present invention.

[0027] Figure 8 is an exemplary drawing specifically showing a cross-section of a linked multi-stage cylinder according to the present invention.

[0028] Fig. 9 is an example diagram showing a state in which the length of the linked multi-stage cylinder illustrated in Fig. 8 has increased.

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0030] FIG. 1 is an exemplary view showing an aerial work vehicle equipped with a boom for an aerial work vehicle according to the present invention, FIG. 2 is an exemplary view showing a boom for an aerial work vehicle according to the present invention, and FIG. 3 is an exemplary view showing a method for changing the length of the boom for an aerial work vehicle shown in FIG. 2.

[0031] Referring to FIG. 1, an aerial work vehicle equipped with a boom for an aerial work vehicle according to an embodiment of the present invention is described.

[0032] For example, a driving device (200) is mounted on a high-altitude work vehicle (400), a boom (100) for high-altitude work vehicles is mounted on the driving device, and a work platform (300) is mounted at the end of the boom (100) for high-altitude work vehicles.

[0033] A boom (100) for an aerial work vehicle is equipped with at least three boom rods and a linked multi-stage cylinder (120) (see FIGS. 2 and 3) according to the present invention that connects the at least three boom rods.

[0034] In this case, the boom (100) for the aerial work vehicle can be equipped with at least two linked multi-stage cylinders (120).

[0035] Referring to FIGS. 2 and 3, a boom for an aerial work vehicle according to an embodiment of the present invention will be described.

[0036] In the following description, the present invention is described using a boom (100) for an aerial work vehicle including a first boom load (111), a second boom load (112), a third boom load (113) and two linked multi-stage cylinders (120).

[0037] That is, the present invention relates to a boom (100) for an aerial work vehicle mounted on a high-altitude ladder truck (hereinafter, simply referred to as an aerial work vehicle) and a linked multi-stage cylinder (120) mounted on the boom for an aerial work vehicle to increase or decrease the length of the boom for an aerial work vehicle.

[0038] In particular, the linked multi-stage cylinder (120) according to the present invention may include at least three cylinder rods, and the at least three cylinder rods may be simultaneously withdrawn or drawn in.

[0039] That is, the cylinder rods constituting the linked multi-stage cylinder (120) according to the present invention are not sequentially moved by hydraulic pressure, but can be simultaneously introduced and withdrawn.

[0040] Accordingly, the boom rods (111, 112, 113) connected to the cylinder rods can also be simultaneously introduced and withdrawn.

[0041] For example, a case in which a boom (100) for an aerial work vehicle according to the present invention includes a first boom load (111), a second boom load (112), a third boom load (113), and a linked multi-stage cylinder (120) is described.

[0042] The linked multi-stage cylinder (120) may include a first cylinder rod (121), a second cylinder rod (122), and a third cylinder rod (123). The first cylinder rod (121), the second cylinder rod (122), and the third cylinder rod (123) may include a first extension (121b), a second extension (122b), and a third extension (123b), respectively. (See FIG. 4, the detailed structures of the first, second, and third cylinder rods will be described later.)

[0043] A first extension (121b) of a linked multi-stage cylinder (120) may be connected to the first boom rod (111), a second extension (122b) of a linked multi-stage cylinder (120) may be connected to the second boom rod (112), and a third extension (123b) of a linked multi-stage cylinder (120) may be connected to the third boom rod (113).

[0044] In this case, when the second extension (122b) moves in the first direction along the first extension (121b), the third extension (123b) can also move in the first direction along the second extension (122b). Accordingly, the second boom rod (112) inserted into the first boom rod (111) can move in the first direction (i.e., the upper direction in FIG. 3). The third boom rod (113) inserted into the second boom rod (112) can also move in the first direction (i.e., the upper direction in FIG. 3).

[0045] That is, in the present invention, the second extension (122b) and the third extension (123b) constituting the linked multi-stage cylinder (120) can move in the first direction simultaneously, and accordingly, the second boom rod (112) and the third boom rod (113) constituting the boom (100) for the aerial work vehicle can also move in the first direction simultaneously.

[0046] Conversely, in a state as illustrated in FIG. 3, when the third extension (123b) moves in the second direction along the second extension (122b), the second extension (122b) can also move in the second direction along the first extension (121b). Accordingly, the third boom rod (113) can move in the second direction (i.e., the downward direction in FIG. 3), and the second boom rod (112) can also move in the second direction (i.e., the downward direction in FIG. 3).

[0047] That is, in the present invention, the second extension (122b) and the third extension (123b) constituting the linked multi-stage cylinder (120) can move in the second direction simultaneously, and accordingly, the second boom rod (112) and the third boom rod (113) constituting the boom (100) for the aerial work vehicle can also move in the second direction simultaneously.

[0048] Hereinafter, the structure and operating principle of the linked multi-stage cylinder (120) according to the present invention are described with reference to FIGS. 4 to 9.

[0049] FIG. 4 is an exemplary drawing schematically showing a cross-section of a linked multi-stage cylinder according to the present invention, FIG. 5 is an exemplary drawing for explaining a method for increasing the length of the linked multi-stage cylinder shown in FIG. 4, FIG. 6 is an exemplary drawing for explaining a method for decreasing the length of the linked multi-stage cylinder shown in FIG. 4, FIG. 7 is an exemplary drawing showing the appearance of a linked multi-stage cylinder according to the present invention, FIG. 8 is an exemplary drawing specifically showing a cross-section of a linked multi-stage cylinder according to the present invention, and FIG. 9 is an exemplary drawing showing a state in which the length of the linked multi-stage cylinder shown in FIG. 8 is increased.

[0050] Referring to FIG. 4, a linked multi-stage cylinder (120) of an embodiment of the present invention is described.

[0051] The linked multi-stage cylinder (120) includes a first cylinder rod (121), a second cylinder rod (122), a third cylinder rod (123), an outlet portion (128), and an inlet portion (127).

[0052] The first cylinder rod (121) includes a first lower plate (121a) and a first extension portion (121b) that extends from the first lower plate toward the upper side of the first lower plate and is formed in a cylindrical shape.

[0053] In this case, the first lower plate (121a) may be formed as a circular plate. The inlet portion (127) may extend through the first lower plate (121a) toward the second cylinder rod (122), and the outlet portion (128) may extend through the first lower plate (121a) and be connected to the internal space of the first extension portion (121b).

[0054] The inner diameter of the first extension portion (121b) may be smaller than or equal to the diameter of the first lower plate (121a). That is, the first extension portion (121b) may be a cylinder extending from the first lower plate (121a).

[0055] The space sealed by the first lower plate (121a), the first extension (121b) and the lower end of the second cylinder rod (hereinafter, simply referred to as the first internal space (121s1)) can be filled with the first hydraulic oil (121x).

[0056] The second cylinder rod (122) is inserted into the internal space of the first extension (121b) through the upper end of the first extension and can reciprocate in the up-and-down direction of the first extension.

[0057] In this case, the lower end of the second cylinder rod (122) is in close contact with the inner surface of the first extension (121b), and the upper end of the second cylinder rod (122) can be spaced apart from the inner surface of the first extension (121b) by a certain distance.

[0058] However, the upper end of the first extension (121b) is in close contact with the outer surface of the second cylinder rod. Accordingly, the internal space of the first extension (121b) and the second cylinder rod (122) can be sealed from the outside. The internal space of the first extension (121b) and the second cylinder rod (122) can be filled with the second hydraulic fluid (122x).

[0059] The third cylinder rod (123) is inserted into the internal space of the second cylinder rod (122) through the upper end of the second cylinder rod (122) and can reciprocate in the up-and-down direction of the second cylinder rod (122).

[0060] In this case, the lower end of the third cylinder rod (123) is in close contact with the inner surface of the second cylinder rod (122), and the upper end of the third cylinder rod (123) can be spaced apart from the inner surface of the second cylinder rod (122) by a certain distance.

[0061] However, the upper end of the second cylinder rod (122) is in close contact with the outer surface of the third cylinder rod (123). Accordingly, the inner space of the second cylinder rod (122) and the third cylinder rod (123) can be sealed from the outside.

[0062] The withdrawal part (128) is connected to the first internal space (121s1) of the first extension part (121b) through the first lower plate (121a), and hydraulic oil (121x) for withdrawal can be injected into the first internal space (121s1) through the withdrawal part (128).

[0063] The inlet portion (127) extends from the first lower plate (121a) through the second cylinder rod (122) into the internal space of the third cylinder rod (123), and hydraulic oil (123x) for inlet can be injected into the internal space of the third cylinder rod (123) through the inlet portion (127).

[0064] That is, among the internal spaces of the first extension (121b), the first internal space (121s1) between the first lower plate (121b) and the lower end of the second cylinder rod (122) is filled with the first hydraulic oil (121x). Among the internal spaces of the first extension (121b), the second internal space (122s2a) between the outer surface of the upper end of the second cylinder rod (122) and the inner surface of the first extension (121b) and the second internal space (122s2b) between the inner surface of the second cylinder rod (122) and the lower end of the third cylinder rod (123) are filled with the second hydraulic oil (122x). Among the internal spaces of the second cylinder rod (122), the third hydraulic oil (123x) is filled in the third a internal space (123s3a) between the outer surface of the upper part of the third cylinder rod (123) and the inner surface of the second cylinder rod (122) and the third b internal space (123s3b) which is the internal space of the third cylinder rod (123).

[0065] In this case, hydraulic oil for withdrawal can be injected into the first internal space (121s1) through the withdrawal portion (128), and the first hydraulic oil (121x) can be discharged through the withdrawal portion (128).

[0066] The second hydraulic oil (122x) does not leak out of the second a internal space (122s2a) and the second b internal space (122s2b), and does not flow into the second a internal space (122s2a) and the second b internal space (122s2b) from the outside. In other words, the second hydraulic oil (122x) filled in the second a internal space (122s2a) and the second b internal space (122s2b) can be isolated from the outside.

[0067] Hydraulic oil for introduction can be injected into the 3b internal space (123s3b) through the introduction portion (127), and the third hydraulic oil (123x) can be discharged through the introduction portion (127).

[0068] Next, when hydraulic oil for withdrawal is injected into the first internal space (121s1) through the withdrawal portion (128), the second cylinder rod (122) moves upward from the lower end of the first cylinder rod. When the second cylinder rod (122) moves, the third cylinder rod (123) moves upward from the lower end of the second cylinder rod.

[0069] That is, in the present invention, the second cylinder rod (122) and the third cylinder rod (123) can be simultaneously moved upward when the hydraulic oil for withdrawal (121x) is injected into the first internal space (121s1).

[0070] For example, a case will be described where a first cylinder rod (121) is connected to a first boom rod (111), an upper end of a second cylinder rod (122) is connected to a second boom rod (112), and an upper end of a third cylinder rod (123) is connected to a third boom rod (113). When the second cylinder rod (122) moves upward, the second boom rod (112) connected to the second cylinder rod moves upward of the first boom rod (111). The third boom rod (113) connected to the third cylinder rod (123) can move upward of the second boom rod (112).

[0071] Next, as described above, the first cylinder rod (121) includes a first lower plate (121a) and a first extension portion (121b) that extends from the first lower plate toward the upper side of the first lower plate and is formed in a cylindrical shape.

[0072] In this case, the second cylinder rod (122) includes a second lower plate (122a) that moves along the inner surface of the first extension portion (121b), a second packing (122d) (see FIG. 8) that is mounted on the outer surface of the second lower plate and is in close contact with the inner surface of the first extension portion (121b), and a second extension portion (122b) that extends from the upper surface of the second lower plate toward the upper side of the second cylinder rod (122).

[0073] A second through hole (122c) is formed in the second extension (122b) to connect the second a internal space (122s2a) and the second b internal space (122s2b).

[0074] That is, the second through hole (122c) penetrates the second extension (122b), and through the second through hole (122c), the second a internal space (122s2a) outside the second extension (122b) and the second b internal space (122s2b) inside the second extension can be connected.

[0075] Accordingly, the second hydraulic oil (122x) may be moved from the second a internal space (122s2a) to the second b internal space (122s2b) through the second through hole (122c), and may be moved from the second b internal space (122s2b) to the second a internal space (122s2a).

[0076] Next, the third cylinder rod (123) includes a third lower plate (123a) that moves along the inner surface of the second extension (122b), a third packing (123d) (see FIG. 8) that is mounted on the outer surface of the third lower plate (123a) and is in close contact with the inner surface of the second extension (122b), and a third extension (123b) that extends from the upper surface of the third lower plate (123a) toward the upper side of the third cylinder rod (123).

[0077] A third through hole (123c) is formed in the third extension (123b) to connect the third a internal space (123s3a) and the third b internal space (123s3b).

[0078] That is, the third through hole (123c) penetrates the third extension (123b), and through the third through hole (123c), the third a internal space (123s3a) outside the third extension (123b) and the second b internal space (123s3b) inside the third extension (123b) can be connected.

[0079] Accordingly, the third hydraulic oil (123x) may be moved from the 3a internal space to the 3b internal space through the third through hole, and may also be moved from the 3b internal space to the 3a internal space.

[0080] Next, the inlet portion (127) extends through the first lower plate (121a), the second lower plate (122a), and the third lower plate (123a) to the third b internal space (123s3b), and the hydraulic oil (123x) for inlet can be injected into the third b internal space (123s3b) through the inlet portion (127). In addition, the third hydraulic oil (123x) can also be discharged to the outside through the inlet portion (127). For this purpose, the end of the inlet portion (127) can be connected to the third b internal space (123s3b).

[0081] Referring to FIGS. 4 and 5, the withdrawal (extension) of the linked multi-stage cylinder of the present embodiment is explained.

[0082] When hydraulic oil for withdrawal is introduced into the first internal space (121s1) through the withdrawal portion (128), the second lower plate (122a) can move along the inner surface of the first extension portion (121b) toward the upper side of the first extension portion by the hydraulic oil for withdrawal.

[0083] When the second lower plate (122a) moves toward the upper side of the first extension (121b), the second hydraulic oil (122x) in the second a internal space (122s2a) can flow into the second b internal space (122s2b) through the second through hole (122c).

[0084] In this case, the third lower plate (123a) can be moved toward the upper side of the second extension (122b) along the inner surface of the second extension (122b) by the second hydraulic oil (122x) flowing into the secondb internal space (122s2b).

[0085] That is, the second lower plate (122a) and the third lower plate (123a) can rise simultaneously, and accordingly, the second cylinder rod (122) and the third cylinder rod (123) can rise simultaneously.

[0086] Referring to FIGS. 3 and 5, the length of a boom (100) for an aerial work vehicle is increased using a multi-stage cylinder of the present embodiment as follows.

[0087] Hydraulic oil for withdrawal is introduced into the first internal space (121s1) through the withdrawal portion (128). Accordingly, the second cylinder rod (122) provided in the first internal space (121s1) can rise along the inside of the first cylinder rod (121). Accordingly, the overall length of the boom (100) increases as the second cylinder rod (122) rises.

[0088] In addition, when the second cylinder rod (122) moves to the upper end of the first cylinder rod (121), the third cylinder rod (123) provided in the second b internal space can be raised along the inside of the second cylinder rod (122) by the second hydraulic oil (122x) flowing into the second b internal space (122s2b). Accordingly, the overall length of the boom (100) increases as the third cylinder rod (123) rises.

[0089] Ultimately, the overall length of the boom (100) increases as the second cylinder rod (122) and the third cylinder rod (123) rise.

[0090] Referring to FIGS. 4 and 6, the return of the linked multi-stage cylinder of the present embodiment is described.

[0091] When hydraulic oil for introduction is introduced into the 3b internal space (123s3b) through the introduction portion (127), the 3rd hydraulic oil (123x) is introduced into the 3a internal space (123s3a) through the 3rd through hole (123c).

[0092] The upper surface of the third lower plate (123a) is pressed by the third hydraulic oil (123x) flowing into the third inner space, so that the third lower plate (123a) can move along the inner surface of the second extension (122b) toward the lower side of the second extension.

[0093] When the third lower plate (123a) moves in the lower direction of the second extension (122b), the second hydraulic oil (122x) in the second b internal space (122s2b) can flow into the second a internal space (122s2a) through the second through hole (122c).

[0094] In this case, the upper surface of the second lower plate (122a) is pressed by the second hydraulic oil (122x) flowing into the second a internal space (122s2a), so that the second lower plate (122a) can move along the inner surface of the first extension (122b) toward the lower side of the first extension.

[0095] That is, the second lower plate (122a) and the third lower plate (123a) can be lowered simultaneously, and accordingly, the second cylinder rod (122) and the third cylinder rod (123) can be lowered simultaneously.

[0096] When the lowering of the second cylinder rod (122) and the third cylinder rod (123) is completed, the return of the linked multi-stage cylinder is completed.

[0097] Referring to FIGS. 3 and 6, the method of reducing the length (return) of a boom (100) for an aerial work vehicle using a multi-stage cylinder of the present embodiment is described as follows.

[0098] Hydraulic oil for introduction is introduced into the 3b internal space (123s3b) through the introduction portion (127), and accordingly, the third hydraulic oil is introduced into the 3a internal space (123s3a). By the third hydraulic oil introduced into the 3a internal space (123s3a), the third cylinder rod (123) provided in the 3b internal space (123s3b) can be lowered along the inside of the second cylinder rod (122). Accordingly, the overall length of the boom (100) is reduced by the amount that the third cylinder rod (123) is lowered.

[0099] In addition, when the third cylinder rod (123) moves to the lower end of the second cylinder rod (122), the second lower plate (122a) of the second cylinder rod (122) provided in the second a internal space (122s2a) can be lowered along the inside of the first cylinder rod (121) by the second hydraulic oil (122x) flowing into the second a internal space (122s2a).

[0100] In addition, when hydraulic oil for introduction is introduced through the introduction portion (127) inserted into the center of the linked multi-stage cylinder (120) according to the present invention and introduced to the third b internal space (123s3b) of the third cylinder rod (123), the third cylinder rod (123) descends in the downward direction of the second cylinder rod (122), and in this case, the second cylinder rod (122) can descend in the downward direction of the first cylinder rod (121).

[0101] Additionally, when hydraulic oil for withdrawal is discharged through the withdrawal portion (128) communicating with the first cylinder rod (121), the second cylinder rod (122) can be lowered in the downward direction of the first cylinder rod (121).

[0102] Accordingly, the overall length of the boom (100) is reduced as the second cylinder rod (122) is lowered.

[0103] Ultimately, the overall length of the boom (100) is reduced as the second cylinder rod (122) and the third cylinder rod (123) are lowered.

[0104] As described above, in the present invention, the second cylinder rod (122) and the third cylinder rod (123) can be raised or lowered simultaneously. Accordingly, the second boom rod (112) and the third boom rod (123) can be raised or lowered simultaneously. Accordingly, the overall length of the boom (100) for the aerial work vehicle can be rapidly increased or decreased. Accordingly, work using the boom (100) for the aerial work vehicle can be performed more quickly.

[0105] Additionally, since the second boom load (112) and the third boom load (113) rise and fall simultaneously, the impact applied to the work platform on which the worker is riding can be reduced. Accordingly, the worker can quickly proceed with the work in a safer posture.

[0106] In this case, it is preferable that the movement amount of the second cylinder rod (122) and the third cylinder rod (123) be set to 1:1, but may be set at various ratios depending on the requirements of the boom (100) for the aerial work vehicle.

[0107] For example, the movement amounts of the second cylinder rod (122) and the third cylinder rod (123) can be adjusted at various ratios by adjusting the inner diameters of the first extension portion (121b) to the third extension portion (123b), the inner diameters of the withdrawal portion and the introduction portion, the volumes of the first extension portion (121b) to the third extension portion (123b), etc.

[0108] Additionally, as the number of boom rods provided on a boom for an aerial work vehicle increases, the number of cylinder rods constituting a linked multi-stage cylinder can also increase in the same manner.

[0109] Additionally, when the number of boom rods provided on the boom for the aerial work vehicle is large, at least two linked multi-stage cylinders can be connected to the boom rods in series.

[0110] For example, when the number of boom rods is 10, a linked multi-stage cylinder including five cylinder rods may be connected to the first to fifth boom rods, and another linked multi-stage cylinder including five cylinder rods may be connected to the sixth to tenth boom rods.

[0111] In this case, the first to fifth boom rods can be raised or lowered simultaneously, and the sixth to tenth boom rods can be raised or lowered simultaneously. In this case, if the timing of injecting the hydraulic oil for withdrawal into the first boom rod and the timing of injecting the hydraulic oil for withdrawal into the sixth boom rod are matched, the first to tenth boom rods can be raised or lowered simultaneously.

[0112] Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering its technical spirit or essential characteristics. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims

1. A first cylinder rod including a first lower plate and a first extension extending upward from the first lower plate; A second cylinder rod inserted into the internal space of the first extension through the upper end of the first extension and reciprocating in the up-and-down direction of the first extension; A third cylinder rod inserted into the inner space of the second cylinder rod through the upper end of the second cylinder rod and reciprocating in the up-and-down direction of the second cylinder rod; A withdrawal part connected to the internal space of the first extension part through the first lower plate and into which hydraulic oil for withdrawal is injected; and It includes an inlet portion extending from the first lower plate to the inner space of the third cylinder rod through the second cylinder rod and into which hydraulic oil for inlet is injected. Among the internal spaces of the first extension, the first internal space between the first lower plate and the lower end of the second cylinder rod is filled with the first hydraulic oil. Among the internal spaces of the first extension, the second hydraulic fluid is filled in the second a internal space between the outer surface of the upper end of the second cylinder rod and the inner surface of the first extension and the second b internal space between the inner surface of the second cylinder rod and the lower end of the third cylinder rod, and the second a internal space and the second b internal space are connected. A multi-stage cylinder having a third hydraulic fluid filled in the third a internal space between the outer surface of the upper end of the third cylinder rod and the inner surface of the second cylinder rod, and the third b internal space, which is the internal space of the third cylinder rod, among the internal spaces of the second cylinder rod, and the second a internal space and the second b internal space are connected to each other.

2. In paragraph 1, A linked multi-stage cylinder in which, when hydraulic oil for withdrawal is injected into the first internal space through the withdrawal portion, the second cylinder rod moves upward from the lower end of the first cylinder rod, and when the second cylinder rod moves, the third cylinder rod moves upward from the lower end of the second cylinder rod.

3. In paragraph 1, The above second cylinder rod, A second lower plate moving along the inner surface of the first extension; and A second extension portion extending from the upper surface of the second lower plate in the upper direction of the second cylinder rod is included. A linked multi-stage cylinder in which a second through hole connecting the second a internal space and the second b internal space is formed in the second extension section.

4. In paragraph 3, The above third cylinder rod, A third lower plate moving along the inner surface of the second extension; and A third extension portion extending from the upper surface of the third lower plate in the upper direction of the third cylinder rod is included. A linked multi-stage cylinder in which a third through hole connecting the thirda internal space and the thirdb internal space is formed in the third extension section.

5. In paragraph 4, A linked multi-stage cylinder in which the above-mentioned inlet portion extends through the first lower plate, the second lower plate, and the third lower plate to the 3b internal space, and the hydraulic oil for inlet is injected into the 3b internal space through the above-mentioned inlet portion.

6. In paragraph 5, When the hydraulic oil for withdrawal flows into the first internal space through the withdrawal portion, the second lower plate moves toward the upper side of the first extension portion along the inner surface of the first extension portion by the hydraulic oil for withdrawal, When the second lower plate moves toward the upper side of the first extension, the second hydraulic oil in the second a internal space flows into the second b internal space through the second through hole. A linked multi-stage cylinder in which the third lower plate moves toward the upper side of the second extension along the inner surface of the second extension by the second hydraulic fluid flowing into the second b internal space.

7. In paragraph 6, When the hydraulic oil for introduction flows into the 3b internal space through the above introduction portion, the 3rd hydraulic oil flows into the 3a internal space through the 3rd through hole, The upper surface of the third lower plate is pressed by the third hydraulic fluid flowing into the third a internal space, and the third lower plate moves along the inner surface of the second extension toward the lower side of the second extension. When the third lower plate moves in the lower direction of the second extension, the second hydraulic oil in the second b internal space flows into the second a internal space through the second through hole, A linked multi-stage cylinder in which the upper surface of the second lower plate is pressed by the second hydraulic fluid flowing into the second a internal space, and the second lower plate moves in the lower direction of the first extension along the inner surface of the first extension.

8. Including a linked multi-stage cylinder of any one of clauses 1 to 7, Including the first boom rod, the second boom rod and the third boom rod, The first boom rod is connected to the first cylinder rod, The second boom rod is connected to the second cylinder rod, A boom for an aerial work vehicle, wherein the third boom rod is connected to the third cylinder rod.

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