Jib system and telescopic oil cylinder thereof

Abstract

The invention discloses a jib system and a telescopic oil cylinder thereof. The disclosed jib system comprises a cylinder jacket (21), a first piston rod (22), a second piston rod (23) and a core pipe (24) for conveying hydraulic oil into the telescopic oil cylinder. The cylinder jacket (21) comprises a first chamber which is sleeved on the first piston rod (22); the first piston rod (22) comprises a second chamber which is sleeved on the second piston rod (23); the second piston rod (23) comprises a third chamber which is sleeved on the core pipe (24); the first piston rod (22) further comprises a first channel (221) which is communicated with the first chamber and the third chamber; and the second piston rod (23) further comprises a second channel (231) which is communicated with the second chamber and the third chamber. The telescopic oil cylinder is simple in structure, and is easy to process; the assembling difficulty and the production cost of the oil cylinder are lowered effectively; convenience of the engineering design is provided; and the economical applicability of engineering vehicles with the jib system is improved.

Description

Technical field [0001] The invention relates to the field of engineering vehicles, and in particular to a telescopic oil cylinder used for an engineering vehicle boom system. In addition, the present invention also relates to a boom system including the above-mentioned telescopic oil cylinder. Background technique [0002] The telescopic function of the boom of engineering vehicles such as telescopic box-type fire trucks and aerial work vehicles can only be realized by the pushing action of hydraulic cylinders. [0003] Please refer to figure 1 , figure 1 It is a schematic cross-sectional view of a typical boom telescopic cylinder in the prior art. [0004] In the current boom system, most of the telescopic cylinders used are double-acting cylinders. The working process is described as follows: [0005] When the cylinder needs to be extended, the oil is supplied through port B and port C. The oil from port B passes through the first core tube 18 to the rodless cavity 13, which pushes...

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Problems solved by technology

[0006] This kind of oil cylinder has a complex structure, and there are two points that require high processing technology

Among them, since there is an oil passage 20 in the primary piston rod 14, the oil passage 20 can be processed with a deep hole drill, but the disadvantage is that the straightness of the drilling is very high, and the wall thickness of the general cylinder rod is relatively small, so it is difficult to ensure a straight line. In addition, the length of the drill bit is limited, and it is difficult to process long oil cylinders; the oil passage 20 can also be welded with two-stage sleeves, leaving a certain gap in the middle. Although this method can process long oil cylinders, it will affect the strength and stability of the cylinder rod. , while cleaning the middle cavity is more difficult

Moreover, in order to ensure that the hydraulic oil can be delivered to the rodless cavity 13, the second core tube 18 needs to adopt a two-stage nesting form, which requires very high straightness and coaxiality. There is a seal for sealing, which requires very strict processing and welding of the core tube, and problems such as core tube bending and oil leakage are prone to occur in the later stage

The telescopic oil cylinders of high-lift vehicles are generally very long, with a stroke of about 10 meters, so the above two points are difficult to meet the use requirements. Even if they are barely achieved, it will be difficult to quantitatively produce due to the complicated process

[0007] At the same time, because the structure of this oil cylinder is too complicated, the later failure rate will be very high, and because there are many failure points, once a problem occurs, it will be difficult to judge the specific cause of the failure, which will seriously affect the production progress and quality stability of the main engine product; and In order to ensure that its complex internal structure can be realized while satisfying the performance, the external dimensions of the oil cylinder must be relatively increased, resulting in an increase in the corresponding structural size and weight. However, once the telescopic load of the boom is too large, in order to ensure that the hydraulic system can provide the maximum If the hydraulic cylinder can output enough thrust, it is necessary to increase the size of the hydraulic cylinder, and the increase in the size of the cylinder will make it difficult to arrange the internal space of the boom structure, so it is necessary to increase the size of the boom, which in turn increases the weight of the boom At the same time, the weight of the telescopic cylinder itself will also increase, which will further increase the telescopic load, which will form a vicious circle and cause the product to fail to meet the design standards

[0008] Moreover, because the existing boom telescopic oil cylinder is a double-acting oil cylinder, it needs high-pressure oil in the rod cavity to retract when retracting, but because the area ratio of the rodless cavity to the rod cavity is generally very large, it leads to When the oil cylinder is retracted, the pressure of the hydraulic system is too high, which cannot meet the use of existing products

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