Open type pressurizing hollow piston rod hydraulic cylinder

Abstract

The invention relates to an open type pressurizing hollow piston rod hydraulic cylinder which mainly comprises a front end cover, a cylinder barrel, a piston, a hollow piston rod assembly, a rear end cover, a one-way valve and the like. A one-way valve and a pressurizing hole are arranged in the output end of the piston rod, and the interior of the hollow piston rod assembly is pressurized through the pressurizing hole to form a high-pressure liquid column so as to improve the bending stability of the hollow piston rod assembly. A pressurizing oil source of the hollow piston rod assembly is independent of a hydraulic cylinder oil source, zero pressure building time can be achieved by pressurizing the hollow piston rod assembly in advance, and the pressurizing value of the hollow piston rod assembly can be regulated and controlled based on the load of the hydraulic cylinder. In addition, different types of pressurizing media can be selected based on the working requirements of the hydraulic cylinder. The pressurizing value and the pressurizing medium in the hollow piston rod assembly can be reasonably selected, the stress distribution of the piston rod can be effectively improved, the instability resistance of the piston rod can be improved, and the adaptability of the hydraulic cylinder under the working conditions of long stroke and high load can be remarkably enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of hollow piston rod hydraulic cylinders, in particular to an open type pressurized hollow piston rod hydraulic cylinder. Background Art

[0002] Hydraulic cylinders are widely used in industrial equipment, engineering machinery, shipping, aerospace and other fields because they can meet various linear motion and power transmission requirements. In the design of modern hydraulic cylinders, in order to reduce dead weight and optimize material utilization efficiency, hollow piston rods have gradually become an important choice.

[0003] In the actual application of long-stroke hydraulic cylinders, such as aerial work platforms, bridge lifting equipment, and large excavators, the hollow piston rod is prone to instability due to its structural characteristics. In order to improve its stability, the method of pressurizing the inner cavity of the hollow piston rod is usually adopted to effectively enhance its anti-instability ability by increasing the stiffness of the piston rod, thereby meeting the performance requirements under harsh working conditions.

[0004] However, currently, the closed pressure charging method is usually used in practical applications. Because the rodless cavity is connected to the inner cavity of the piston rod, and the oil enters the inner cavity of the hollow piston rod through a one-way valve, the inner cavity pressure value is the maximum pressure value of the oil entering the rodless cavity. This type of pressure charging method takes a long time to build up pressure and has a low pressure value, which can easily lead to slow system response speed and insufficient load-bearing capacity, which may affect the stability and working efficiency of the hydraulic cylinder and reduce the overall performance and service life. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide an open-type pressurized hollow piston rod hydraulic cylinder, which can effectively solve the problems involved in the closed-type pressurized hollow piston rod cylinder, such as uncontrollable pressurization value, long pressure building time, and single pressurization medium, and provide strong technical support for the application and development of hollow piston rod hydraulic cylinders.

[0006] The technical solution adopted by the present invention is as follows:

[0007] An open-type pressurized hollow piston rod hydraulic cylinder proposed in the present invention comprises a front end cover, a cylinder barrel, a piston, a hollow piston rod assembly, a piston rod output end and a rear end cover; the front end cover and the rear end cover are coaxially fixedly connected to the front and rear ends of the cylinder barrel respectively; the hollow piston rod assembly is coaxially arranged inside the cylinder barrel and cooperates with the inner ring moving pair of the rear end cover; the piston rod output end is located on the outside of the rear end cover and is coaxially fixedly connected to the rear end of the hollow piston rod assembly; the piston is coaxially fixedly connected to the front side of the hollow piston rod assembly and cooperates with the inner wall moving pair of the cylinder barrel; one side of the front end cover is provided with an oil filling hole connected to the rodless cavity of the cylinder barrel; the rear side of the cylinder barrel is provided with an oil outlet hole connected to the rod cavity of the cylinder barrel; the front side of the interior of the piston rod output end is provided with a hollow structure connected to the inner cavity of the hollow piston rod assembly, and a one-way valve is provided inside the hollow structure; a pressurizing hole is provided on one side of the middle part of the piston rod output end; the pressurizing hole is connected to the inner cavity of the hollow piston rod assembly through a one-way valve.

[0008] Furthermore, the hollow piston rod assembly includes a piston rod end cover and a hollow piston barrel; the hollow piston barrel is coaxially arranged inside the cylinder barrel and cooperates with the inner ring moving pair of the rear end cover; the piston rod end cover is coaxially fixed to the front end inner ring of the hollow piston barrel; the outer circumferential surface of the front side of the hollow piston barrel is provided with a thread, and the piston is correspondingly threadedly connected to the front side of the hollow piston barrel; the rear end of the hollow piston barrel is coaxially matched with and fixedly connected to the front end of the piston rod output end; the rear end of the inner cavity of the hollow piston barrel is correspondingly connected to the hollow structure inside the piston rod output end.

[0009] Furthermore, a retaining spring is used to limit the front end of the one-way valve and the inner wall of the piston rod output end; and a one-way valve static seal is provided between the outer circumferential surface of the one-way valve and the inner wall of the piston rod output end.

[0010] Furthermore, a piston sealing group is provided in the middle of the outer circumferential surface of the piston.

[0011] Furthermore, a piston rod static seal is provided on the front outer circumferential surface of the hollow piston cylinder.

[0012] Furthermore, a front end cover static seal is provided on the outer circumferential surface of the portion of the front end cover located in the cylinder barrel.

[0013] Furthermore, a rear end cover static seal is provided on the outer circumferential surface of the portion of the rear end cover located in the cylinder barrel; and a piston rod dynamic seal group is provided on the inner circumferential surface of the rear end cover.

[0014] Furthermore, the front end cover is coaxially fixedly connected to the front end of the cylinder barrel by welding; and the rear end cover is coaxially fixedly connected to the rear end of the cylinder barrel by bolting.

[0015] Furthermore, the pressurized medium inside the hollow piston cylinder is hydraulic oil, nitrogen or air.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention adopts an open charging method to realize the free setting of the inner cavity pressure value of the piston rod, so that the hydraulic cylinder can flexibly adjust the inner cavity pressure according to the specific working conditions. By reasonably adjusting the inner cavity pressure, it can not only effectively improve the stress distribution of the piston rod and improve its anti-instability ability, but also enhance the adaptability of the hydraulic cylinder under long stroke and high load conditions. The freely set pressure value helps to strike a balance between lightweight design and high stability, reduce the risk of failure caused by external loads, extend the service life of the equipment, and further improve the working reliability and efficiency of the hydraulic system. In addition, the charging medium of the hollow piston rod can be freely selected, such as hydraulic oil, nitrogen, air and other fluids. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the overall structure of an open type pressurized hollow piston rod hydraulic cylinder proposed by the present invention.

[0019] Among them, the figure markings are: 1-front end cover; 2-oil filling hole; 3-front end cover static seal; 4-piston rod end cover; 5-piston; 6-piston seal group; 7-piston rod static seal; 8-cylinder barrel; 9-hollow piston barrel; 10-oil outlet hole; 11-rear end cover static seal; 12-rear end cover; 13-piston rod dynamic seal group; 14-circlip; 15-check valve static seal; 16-check valve; 17-pressurization hole; 18-piston rod output end; 19-hollow piston rod assembly. DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] It should be noted that, in the description of the present invention, the terms "up", "down", "top", "bottom", "one side", "the other side", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device or element must have a specific orientation, be constructed and operated in a specific orientation.

[0022] See attached Figure 1 , a specific structure of an embodiment of an open type pressurized hollow piston rod hydraulic cylinder proposed by the present invention is given. The hydraulic cylinder comprises a front end cover 1, a cylinder barrel 8, a piston 5, a hollow piston rod assembly 19, a piston rod output end 18 and a rear end cover 12.

[0023] The front end cover 3 is coaxially fixedly connected to the front end of the cylinder 8 by welding; the rear end cover 12 is coaxially fixedly connected to the rear end of the cylinder 8 by bolting. In this embodiment, the outer circumferential surface of the portion of the front end cover 1 located in the cylinder 8 is provided with a front end cover static seal 3; the outer circumferential surface of the portion of the rear end cover 12 located in the cylinder 8 is provided with a rear end cover static seal 11.

[0024] The hollow piston rod assembly 19 is coaxially arranged inside the cylinder 8, and the outer ring of the hollow piston rod assembly 19 is matched with the inner ring of the rear end cover 12 in a moving pair; the piston rod output end 18 is located outside the rear end cover 12 and is coaxially fixed to the rear end of the hollow piston rod assembly 19; the piston 5 is coaxially fixed to the front outside of the hollow piston rod assembly 19, and the outer ring of the piston 5 is matched with the inner wall of the cylinder 8 in a moving pair, and a piston sealing group 6 is provided in the middle of the outer circumferential surface of the piston 5.

[0025] An oil filling hole 2 communicating with the rodless cavity of the cylinder 8 is disposed on one side of the front end cover 1 ; an oil outlet hole 10 communicating with the rod cavity in the cylinder 8 is disposed on the rear side of the cylinder 8 .

[0026] The front side of the interior of the piston rod output end 18 is arranged as a hollow structure connected with the inner cavity of the hollow piston rod assembly 19, and a one-way valve 16 is coaxially installed inside the hollow structure; a pressurizing hole 17 is arranged on one side of the middle part of the piston rod output end 18; the pressurizing hole 17 is connected with the inner cavity of the hollow piston rod assembly 19 via the one-way valve 16, and the interior of the hollow piston rod assembly 19 can be pressurized through the pressurizing hole 17.

[0027] In this embodiment, the hollow piston rod assembly 19 includes a piston rod end cover 4 and a hollow piston cylinder 9; the hollow piston cylinder 9 is coaxially arranged inside the cylinder 8 and the outer ring corresponds to the inner ring moving pair of the rear end cover 12; and the inner ring circumferential surface of the rear end cover 12 is provided with a piston rod dynamic seal group 13.

[0028] The front end inner ring of the hollow piston cylinder 9 is provided with a countersunk hole, and is coaxially matched with the piston rod end cover 4 through the countersunk hole, and the two are fixedly connected by welding; the front side outer circumferential surface of the hollow piston cylinder 9 is provided with a thread, and the piston 5 is correspondingly threadedly connected to the front side of the hollow piston cylinder 9, and a piston rod static seal 7 is provided between the front side outer circumferential surface of the hollow piston cylinder 9 and the inner ring of the piston 5; the rear end inner ring of the hollow piston cylinder 9 is provided with a countersunk hole, and the front end outer ring of the piston rod output end 18 is provided with a countersunk hole, and the two ends are spliced ​​and coaxially matched and fixedly connected by welding; the inner cavity of the hollow piston cylinder 9 is correspondingly connected to the hollow structure inside the piston rod output end 18.

[0029] The front end of the one-way valve 16 is limited by a retaining spring 14 against the inner wall of the piston rod output end 18 ; a one-way valve static seal 15 is provided between the outer circumferential surface of the one-way valve 16 and the inner wall of the piston rod output end 18 .

[0030] The hollow piston cylinder 9 can be pressurized through the pressurizing hole 17. After pressurization, the oil cannot flow out through the one-way valve 16, thereby achieving a pressure-maintaining effect. The oil source of the pressurizing hole 17 and the oil source of the oil injection hole 2 are two different oil sources, and the pressure value Pc at the pressurizing hole 17 is not related to the pressure value PA at the oil injection hole 2.

[0031] The hollow piston rod assembly 19 can be pressurized separately after installation, and does not need to be pressurized through the oil filling hole 2 when the hydraulic cylinder is working; and the Pc value can be adjusted according to the load of the hydraulic cylinder, and its pressure value can be larger or smaller than the PA value.

[0032] The inner cavity of the hollow piston cylinder 9 can select hydraulic oil, nitrogen, air and other fluids as the pressurizing medium; the pressurizing medium can be determined according to the use environment and requirements of the hydraulic cylinder. For example, gas medium can be selected for lightweight requirements, and inert gas medium such as nitrogen can be selected for flammable and explosive environments.

[0033] The specific working principle of the present invention is as follows: before the hollow piston rod hydraulic cylinder is assembled and the hydraulic cylinder is working, the pressurizing medium is injected into the hollow piston cylinder 9 through the pressurizing hole 17 and the one-way valve 16 by means of the pressurizing device, and the pressurizing is completed when the pressurizing medium fills the entire cavity and the pressure is established. Under the action of the one-way valve 16 and the one-way valve static seal 15, a stable liquid column / gas column with a certain pressure is formed in the hollow piston cylinder 9. When the hydraulic cylinder starts to work, unlike the existing hollow hydraulic cylinder pressurizing method (pressurizing the hollow piston rod through the oil in the rodless cavity of the hydraulic cylinder), the hollow piston cylinder 9 in the present invention has completed the pressurization in advance, which reduces the pressure building time and increases the stability of the hydraulic cylinder when working. In addition, the present invention can freely set the pressure value in the hollow piston cylinder 9, which is independent of the pressure value of the rodless cavity of the hydraulic cylinder, so that the stiffness of the hydraulic cylinder piston rod can be freely adjusted.

[0034] Matters not covered in the present invention are all known technologies.

[0035] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An open type pressurized hollow piston rod hydraulic cylinder, characterized in that: The hydraulic cylinder includes a front end cover, a cylinder barrel, a piston, a hollow piston rod assembly, a piston rod output end and a rear end cover; the front end cover and the rear end cover are coaxially fixed to the front and rear ends of the cylinder barrel respectively; the hollow piston rod assembly is coaxially arranged inside the cylinder barrel and cooperates with the inner ring moving pair of the rear end cover; the piston rod output end is located outside the rear end cover and is coaxially fixed to the rear end of the hollow piston rod assembly; the piston is coaxially fixed to the front side of the hollow piston rod assembly and cooperates with the inner wall moving pair of the cylinder barrel; one side of the front end cover is provided with an oil filling hole connected to the rodless cavity of the cylinder barrel; the rear side of the cylinder barrel is provided with an oil outlet hole connected to the rod cavity of the cylinder barrel; the front side of the interior of the piston rod output end is provided with a hollow structure connected to the inner cavity of the hollow piston rod assembly, and a one-way valve is provided inside the hollow structure; a pressurizing hole is provided on one side of the middle part of the piston rod output end; the pressurizing hole is connected to the inner cavity of the hollow piston rod assembly through a one-way valve.

2. An open type pressurized hollow piston rod hydraulic cylinder according to claim 1, characterized in that: The hollow piston rod assembly includes a piston rod end cover and a hollow piston barrel; the hollow piston barrel is coaxially arranged inside the cylinder barrel and cooperates with the inner ring moving pair of the rear end cover; the piston rod end cover is coaxially fixedly connected to the front end inner ring of the hollow piston barrel; the outer circumferential surface of the front side of the hollow piston barrel is provided with a thread, and the piston is correspondingly threadedly connected to the front side of the hollow piston barrel; the rear end of the hollow piston barrel is coaxially matched with and fixedly connected to the front end of the piston rod output end; the rear end of the inner cavity of the hollow piston barrel is correspondingly connected to the hollow structure inside the piston rod output end.

3. An open type pressurized hollow piston rod hydraulic cylinder according to claim 1, characterized in that: The front end of the one-way valve and the inner wall of the piston rod output end are limited by a retaining spring; a one-way valve static seal is arranged between the outer circumferential surface of the one-way valve and the inner wall of the piston rod output end.

4. An open type pressurized hollow piston rod hydraulic cylinder according to claim 1, characterized in that: A piston sealing group is arranged at the middle part of the outer circumferential surface of the piston.

5. An open type pressurized hollow piston rod hydraulic cylinder according to claim 2, characterized in that: The front outer circumferential surface of the hollow piston cylinder is provided with a piston rod static seal.

6. An open type pressurized hollow piston rod hydraulic cylinder according to claim 1, characterized in that: The outer circumferential surface of the portion of the front end cover located in the cylinder barrel is provided with a front end cover static seal.

7. An open type pressurized hollow piston rod hydraulic cylinder according to claim 1, characterized in that: The outer circumferential surface of the rear end cover located in the cylinder barrel is provided with a rear end cover static seal; the inner circumferential surface of the rear end cover is provided with a piston rod dynamic seal group.

8. An open type pressurized hollow piston rod hydraulic cylinder according to claim 1, characterized in that: The front end cover is coaxially fixedly connected to the front end of the cylinder barrel by welding; the rear end cover is coaxially fixedly connected to the rear end of the cylinder barrel by bolting.

9. An open type pressurized hollow piston rod hydraulic cylinder according to claim 2, characterized in that: The pressurized medium inside the hollow piston cylinder is hydraulic oil, nitrogen or air.

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