Piston-seal-free hydraulic cylinder and hydraulic system

Abstract

The invention discloses a hydraulic cylinder without a piston seal and a hydraulic system, belongs to the technical field of hydraulic cylinders, and aims to solve the problems that the hydraulic cylinder with the piston seal is easy to generate internal leakage and inconvenient to maintain and the pipe distribution of the hydraulic system is limited. The hydraulic cylinder without piston sealing comprises a first hydraulic cylinder module and a second hydraulic cylinder module. The first hydraulic cylinder module comprises a first cylinder body and a first hydraulic column, the second hydraulic cylinder module comprises a second cylinder body and a second hydraulic column, and the first hydraulic column and the second hydraulic column can synchronously move in the first cylinder body and the second cylinder body respectively. According to the hydraulic cylinder without piston sealing, internal leakage of the hydraulic cylinder can be avoided, maintenance is convenient, the pipeline layout of a hydraulic system is flexible, and the requirements of various different working conditions and application scenes are met.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic cylinder technology, and relates to a piston-seal-free hydraulic cylinder and hydraulic system. Background Technology

[0002] Existing hydraulic cylinders require guide sealing assemblies in the rod chamber and piston seals in the rodless chamber to ensure zero internal leakage. Because of the piston seal requirement, the entire cylinder body has high requirements for surface roughness, precision, and dimensional tolerances. Furthermore, maintenance necessitates complete disassembly of the hydraulic cylinder, removing the entire piston rod and piston. Moreover, the positions of the hydraulic cylinder's inlet and outlet ports must consider the influence of the rod and rodless chambers, meaning most ports can only be located near the cylinder ends, limiting the flexibility of the hydraulic system's piping layout. Summary of the Invention

[0003] Based on the above analysis, the present invention aims to provide a piston-seal-free hydraulic cylinder and hydraulic system to solve the problems of internal leakage, inconvenient maintenance, and limited piping of hydraulic systems caused by piston seals.

[0004] The objective of this invention is mainly achieved through the following technical solutions.

[0005] A first aspect of the present invention provides a pistonless hydraulic cylinder, comprising a first hydraulic cylinder module and a second hydraulic cylinder module; the first hydraulic cylinder module includes a first cylinder body and a first hydraulic column, and the second hydraulic cylinder module includes a second cylinder body and a second hydraulic column, wherein the first hydraulic column and the second hydraulic column are capable of moving synchronously within the first cylinder body and the second hydraulic column, respectively.

[0006] Furthermore, a first cavity is provided between the inner wall of the first cylinder and the first hydraulic column, and a second cavity is provided between the inner wall of the second cylinder and the second hydraulic column.

[0007] Furthermore, both the first cavity and the second cavity are sealed cavities.

[0008] Furthermore, gaps are provided between the outer walls of the first hydraulic column and the second hydraulic column and the inner walls of the first cylinder and the second cylinder, respectively.

[0009] Furthermore, the center lines of the first and second cylinder blocks are parallel.

[0010] Furthermore, the first end of the first cylinder and the second cylinder are respectively provided with a first guide sealing assembly A and a second guide sealing assembly A.

[0011] Furthermore, it also includes a first connector, and both the first guide sealing assembly A and the second guide sealing assembly A are fitted around the outer periphery of the first connector and are guided and sealed to the first connector.

[0012] Furthermore, it also includes a second connector, through which the first cylinder block and the second cylinder block are fixedly connected.

[0013] Furthermore, the first cylinder block and the second cylinder block also include a first oil port and a second oil port, with oil alternately entering and exiting through the first oil port and the second oil port.

[0014] Furthermore, both the first hydraulic cylinder module and the second hydraulic cylinder module include a pistonless seal structure.

[0015] Furthermore, the second ends of the first cylinder and the second cylinder are respectively provided with a first guide sealing assembly B and a second guide sealing assembly B.

[0016] Furthermore, the first guide sealing component B and the second guide sealing component B are respectively sleeved on the outer periphery of the first hydraulic column and the second hydraulic column and are respectively guided and sealed to the first hydraulic column and the second hydraulic column.

[0017] Furthermore, the two ends of the first connector are fixedly connected to the first ends of the first hydraulic column and the second hydraulic column, respectively.

[0018] Furthermore, the synchronous sliding of the first hydraulic column and the second hydraulic column can cause the volumes of the first cavity and the second cavity to increase or decrease in turn.

[0019] A second aspect of the present invention provides a pistonless hydraulic system comprising an oil pump, a control valve, an actuator, and a pistonless hydraulic cylinder as described in any of the first aspects of the present invention.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] 1. The pistonless hydraulic cylinder of the present invention, by setting two hydraulic cylinder modules, uses the synchronous movement of the first hydraulic column and the second hydraulic column to transmit the hydraulic kinetic energy of the two cylinders, which can effectively avoid the internal leakage that is easy to be generated by the traditional piston sealing structure, and significantly improve the operating efficiency and service life of the hydraulic system.

[0022] 2. The pistonless hydraulic cylinder of the present invention achieves a pistonless sealing structure by connecting two coordinated hydraulic columns to the guide seals of two cylinder bodies respectively. Since the guide seal assembly has higher wear resistance and anti-eccentric load capacity compared with the piston seal, it effectively avoids the early wear and leakage problems caused by uneven radial force of traditional piston seal, and can even achieve the effect of zero internal leakage.

[0023] 3. The pistonless hydraulic cylinder of the present invention reduces frictional resistance and heat generation risk by not using traditional piston seals, improves energy transfer efficiency, and maintains stable sealing performance under frequent reciprocating and high-load conditions, significantly extending the service life and maintenance cycle of the hydraulic cylinder. Furthermore, the piston seal structure does not need to be disassembled during assembly and maintenance, simplifying the maintenance process and reducing operating costs.

[0024] 4. The pistonless hydraulic cylinder of the present invention, due to its pistonless sealing structure, allows the oil port to be arranged at any position on the cylindrical surface of the hydraulic housing, which facilitates the pipeline layout and integration of the hydraulic system, improves the system adaptability and installation freedom, and is especially suitable for complex working conditions where space is limited or multi-directional piping is required.

[0025] 5. The pistonless hydraulic cylinder of the present invention, due to the adoption of a pistonless sealing structure, allows for adjustment of the position between the first hydraulic cylinder module and the second hydraulic cylinder module and enables different model combinations, further improving the product's versatility and flexibility, and enabling it to adapt to the needs of various working conditions and application scenarios.

[0026] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings, which are particularly pointed out. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the piston-sealed hydraulic cylinder according to Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the extended state of the first hydraulic cylinder module of the pistonless hydraulic cylinder according to Embodiment 1 of the present invention.

[0029] Figure 3 This is a schematic diagram of the extended state of the second hydraulic cylinder module of the pistonless hydraulic cylinder according to Embodiment 1 of the present invention.

[0030] Figure 4 This is a schematic diagram of the overall structure of the piston-sealed hydraulic cylinder according to Embodiment 2 of the present invention;

[0031] Figure 5 This is a schematic diagram of the overall structure of the pistonless hydraulic cylinder of Embodiment 3 of the present invention.

[0032] Figure label:

[0033] 1-First hydraulic cylinder module;

[0034] 11-First cylinder block; 111-First cavity; 112-First oil port; 113-First guide sealing assembly A; 114-First guide sealing assembly B; 12-First hydraulic column;

[0035] 2-Second hydraulic cylinder module;

[0036] 21-Second cylinder body; 211-Second cavity; 212-Second oil port; 213-Second guide sealing assembly A; 214-Second guide sealing assembly B; 22-Second hydraulic column;

[0037] 3-First connector;

[0038] 31-First locking key; 32-First nut; 33-First sealing ring; 34-Second locking key; 35-The

[0039] Two nuts; 36 - Second sealing ring;

[0040] 301-First connecting rod; 3011-First rack; 302-Second connecting rod; 3021-Second rack; 303-Transmission gear;

[0041] 4-Second connector. Detailed Implementation

[0042] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0043] Example 1

[0044] This embodiment discloses a piston-seal-free hydraulic cylinder, such as... Figure 1 As shown, it includes a first hydraulic cylinder module 1 and a second hydraulic cylinder module 2; the first hydraulic cylinder module 1 includes a first cylinder body 11 and a first hydraulic column 12, and the second hydraulic cylinder module 2 includes a second cylinder body 21 and a second hydraulic column 22, and the first hydraulic column 12 and the second hydraulic column 22 can move synchronously in the first cylinder body 11 and the second cylinder body 21 respectively.

[0045] The pistonless hydraulic cylinder of this embodiment uses two hydraulic cylinder modules for synchronous dual-cylinder drive. The first hydraulic column 12 and the second hydraulic column 22 are used to transmit the kinetic energy of the hydraulic pressure and convert it into synchronous linear motion of the two hydraulic columns. This can effectively avoid the internal leakage that is easy to occur in traditional piston sealing structures, and significantly improve the operating efficiency and service life of the hydraulic system.

[0046] Specifically, such as Figure 1As shown, both the first hydraulic cylinder module 1 and the second hydraulic cylinder module 2 are connected and assembled to the same oil supply system. A first cavity 111 is provided between the inner wall of the first cylinder body 11 and the first hydraulic column 12, and a second cavity 211 is provided between the inner wall of the second cylinder body 21 and the second hydraulic column 22. Both the first cavity 111 and the second cavity 211 are sealed cavities. When the first hydraulic column 12 and the second hydraulic column 22 move synchronously, the volumes of the first cavity 111 and the second cavity 211 change synchronously.

[0047] Specifically, such as Figure 1 and Figure 2 As shown, the first cylinder 11 and the second cylinder 21 also include a first oil port 112 and a second oil port 212, respectively. The first oil port 112 and the second oil port 212 alternately supply and discharge oil, so that the first cylinder 11 and the second cylinder 21 can be connected to the same hydraulic circuit, so that the hydraulic oil alternately enters and exits between the two chambers, realizing the circulation supply and recovery of oil, thereby simplifying the system pipeline layout, effectively reducing pipeline complexity and improving system response speed.

[0048] In some embodiments, such as Figure 1 and Figure 2 As shown, the piston-free hydraulic cylinder also includes a first connecting member 3. The two ends of the first connecting member 3 are fixedly connected to the first ends of the first hydraulic column 12 and the second hydraulic column 22, respectively, so that the first hydraulic column 12 and the second hydraulic column 22 can slide synchronously and the volume changes of the first cavity 111 and the second cavity 211 are inversely proportional.

[0049] This embodiment achieves dynamic volume balance between the two sealed cavities by synchronously sliding the first hydraulic column 12 and the second hydraulic column 22, effectively ensuring the consistency of movement of the first hydraulic column 12 and the second hydraulic column 22 in a hydraulic system, so that the hydraulic medium can flow alternately in the first cavity 111 and the second cavity 211, thereby driving the load to operate smoothly.

[0050] In some embodiments, the center lines of the first cylinder 11 and the second cylinder 21 coincide, and the extension directions of the first hydraulic column 12 and the second hydraulic column 22 are opposite.

[0051] For example, the first hydraulic column 12 and the second hydraulic column 22 are hollow columns, which can reduce weight and cost while ensuring rigidity, and facilitate connection with the first connecting member 3.

[0052] For example, such as Figure 2As shown, the first connecting member 3 is a rigid linear rod. One end of the first connecting member 3 passes through the first end of the first cylinder body 11 and is detachably connected to the first hydraulic column 12 via a first latch 31 and a first nut 32. The other end passes through the first end of the second cylinder body 21 and is detachably connected to the second hydraulic column 22 via a second latch 33 and a first nut 34. Both ends of the first connecting member 3 are provided with steps, and the end faces of the steps at both ends are respectively provided with a first sealing ring 33 and a second sealing ring 36 between the end faces of the first hydraulic column 12 and the second hydraulic column 22 to achieve sealing at the connection. Optionally, other detachable connection methods can also be used to facilitate maintenance and replacement. The rigid structure of the first connecting member 3 effectively ensures the consistency of the movement of the two cylinders, avoids the phenomenon of uneven load caused by uneven force, and further improves the stability and reliability of the system operation.

[0053] In some embodiments, such as Figure 1 As shown, the system also includes a second connecting member 4, through which the first ends of the first cylinder body 11 and the second cylinder body 21 are fixedly connected. For example, the second connecting member 4 is a connecting sleeve, with its two ends fixedly connected to the first ends of the first cylinder body 11 and the second cylinder body 21, respectively. Preferably, the second connecting member 4 is fixedly connected to the cylinder body by a threaded connection, ensuring a stable structure and easy assembly and disassembly. The length of the connecting sleeve can be flexibly adjusted according to the actual installation space to adapt to the layout of hydraulic systems with different stroke requirements.

[0054] To achieve a seal at the first end of the two cylinders, such as Figure 2 As shown, the first cylinder body 11 and the second cylinder body 21 are respectively provided with a first guide sealing assembly A113 and a second guide sealing assembly A213 at their first ends. The first guide sealing assembly A113 and the second guide sealing assembly A213 are both fitted around the outer periphery of the first connecting member 3 and are guided and sealed to the first connecting member 3, so that the first connecting member 3 maintains good guiding and sealing performance when sliding relative to the first ends of the first cylinder body 11 and the second cylinder body 21, effectively preventing hydraulic medium leakage and reducing motion resistance.

[0055] To achieve a seal at the second end of the two cylinders, such as Figure 2 As shown, the second ends of the first cylinder 11 and the second cylinder 21 are respectively provided with a first guide sealing assembly B114 and a second guide sealing assembly B214. Specifically, the second ends of the first hydraulic column 12 and the second hydraulic column 22 are located outside the first cylinder 11 and the second cylinder 21, respectively. The first guide sealing assembly B114 and the second guide sealing assembly B214 are respectively sleeved on the outer periphery of the first hydraulic column 12 and the second hydraulic column 22 and respectively guide and seal with the first hydraulic column 12 and the second hydraulic column 22. This ensures that during the reciprocating motion of the first hydraulic column 12 and the second hydraulic column 22, the guide sealing assemblies on their outer periphery effectively maintain the sealing performance of the second ends, preventing external impurities from entering and reducing internal hydraulic oil leakage.

[0056] It should be noted that both guide sealing assembly A and guide sealing assembly B in this embodiment adopt existing standard guide sealing assemblies.

[0057] After the piston-sealed hydraulic cylinder of this embodiment is connected to the hydraulic system, as shown... Figure 2 As shown, when oil enters through the first port 112, the pressure inside the first cavity 111 increases, pushing the first hydraulic column 12 towards the second end of the first cylinder 11. The first hydraulic column 12 extends, simultaneously driving the second hydraulic column 22 to move synchronously through the first connecting member 3, reducing the volume of the second cavity 211 and pushing the hydraulic oil out through the second port 212; Figure 3 As shown, when oil enters through the second oil port 212, the pressure inside the second cavity 211 increases, pushing the second hydraulic column 22 to move towards the second end of the second cylinder 21. The second hydraulic column 22 performs an extension action, and at the same time, it drives the first hydraulic column 12 to move synchronously through the first connecting piece 3, so that the volume of the first cavity 111 decreases and pushes the hydraulic oil out through the first oil port 112.

[0058] This embodiment of the pistonless hydraulic cylinder achieves a pistonless sealing structure by connecting two coordinated hydraulic columns to guide seals on two cylinder bodies. Compared to piston seals, the guide seal assembly offers higher wear resistance and resistance to eccentric loads, effectively avoiding early wear and leakage problems caused by uneven radial forces in traditional piston seals, and even achieving zero internal leakage. Furthermore, the absence of traditional piston seals reduces frictional resistance and the risk of overheating, improving energy transfer efficiency. It maintains stable sealing performance even under frequent reciprocating and high-load conditions, significantly extending the service life and maintenance cycle of the hydraulic cylinder. In addition, the hydraulic cylinder of this embodiment does not require disassembly of the piston seal structure during assembly and maintenance, simplifying the repair process and reducing operating costs.

[0059] To ensure smooth oil inlet and outlet, gaps are provided between the outer walls of the first hydraulic column 12 and the second hydraulic column 22 and the inner walls of the first cylinder 11 and the second cylinder 21, respectively, so as to prevent the first hydraulic column 12 and the second hydraulic column 22 from interfering with the inner walls of the cylinders due to thermal expansion or deformation under force during operation, or even affecting the normal oil inlet and outlet.

[0060] The hydraulic cylinder in this embodiment, due to its pistonless sealing structure, allows the oil port to be arranged at any position on the cylindrical surface of the hydraulic housing, which facilitates the pipeline layout and integration of the hydraulic system, improves the system adaptability and installation freedom, and is especially suitable for complex working conditions where space is limited or multi-directional piping is required.

[0061] To adapt to different installation environments and stroke requirements, the position between the first hydraulic cylinder module 1 and the second hydraulic cylinder module 2 can be adjusted and configured in different combinations. For example, the diameter and length of the first cylinder body 11 and the second cylinder body 21 can be selected according to actual load and stroke requirements. The total stroke of the hydraulic cylinder can be flexibly configured by adjusting the length of the first connecting member 3 and the second connecting member 4, thereby improving product versatility and facilitating mass production and rapid replacement.

[0062] Example 2

[0063] The pistonless hydraulic cylinder disclosed in this embodiment differs from that in Embodiment 1 in that the first cylinder body 11 and the second cylinder body 21 are staggered and the first hydraulic column 12 and the second hydraulic column 22 extend in opposite directions.

[0064] In some embodiments, such as Figure 4 As shown, the first connecting member 3 is a Z-shaped rod, with its two ends connected to the ends of the first hydraulic column 12 and the second hydraulic column 22, respectively. The middle section spans the misaligned area between the two cylinders, achieving synchronous transmission of force and displacement. This structure ensures synchronous movement of the first hydraulic column 12 and the second hydraulic column 22 while effectively adapting to the layout requirements of misaligned cylinder axes, improving the flexibility of installation space utilization. This arrangement is particularly suitable for hydraulic drive scenarios in narrow or asymmetrical spaces, achieving a balance between structural compactness and adaptability to operating conditions without sacrificing output performance.

[0065] It should be noted that, considering the additional bending moment caused by the eccentric load on the Z-shaped rod, the rod body is preferably made of high-strength lightweight alloy. In the design, simulation and stress analysis can be used to optimize the performance, so that the stress distribution in each part is uniform during the transmission of push and pull forces, avoiding fatigue failure caused by stress concentration. Rounded transitions can also be set at the turning points to enhance the structural stiffness and bending resistance.

[0066] Example 3

[0067] The pistonless hydraulic cylinder disclosed in this embodiment differs from that in Embodiment 1 in that the first cylinder body 11 and the second cylinder body 21 are arranged side by side and the first hydraulic column 12 and the second hydraulic column 22 extend in the same direction.

[0068] In some embodiments, such as Figure 5As shown, the first connecting member 3 includes a gear and rack transmission structure, comprising a first connecting rod 301, a second connecting rod 302, and a transmission gear 303. One end of the first connecting rod 301 and the second connecting rod 302 are respectively fixed to the ends of the first hydraulic column 12 and the second hydraulic column 22, and the other end is respectively provided with a first rack 3011 and a second rack 3021. The transmission gear 303 is located between the two and meshes with the first rack 3011 and the second rack 3021, thereby realizing the synchronous movement of the first hydraulic column 12 and the second hydraulic column 22 through the transmission of the gear and rack.

[0069] When the first oil port 112 is the oil inlet, hydraulic oil enters the first cylinder 11, pushing the first hydraulic column 12 to extend. The first connecting rod 301 then moves towards the first cylinder 11. The first rack 3011 drives the transmission gear 303 to rotate, which in turn drives the second rack 3021 to move in the opposite direction. This causes the second connecting rod 302 to synchronously retract the second hydraulic column 22. At this time, the second oil port 212 becomes the oil outlet, and hydraulic oil is discharged from the second cylinder 21. When the second oil port 212 is the oil inlet, the direction of movement is reversed.

[0070] The pistonless, seal-free hydraulic cylinder of this embodiment achieves reverse synchronization of the two hydraulic cylinders' movements by incorporating a first connecting member 3 with a gear and rack transmission mechanism. This enables coordinated action of the first hydraulic module 1 and the first hydraulic module 2 in a parallel arrangement. Mechanical coupling ensures the motion accuracy and synchronous response of the first hydraulic cylinder 12 and the second hydraulic cylinder 22, making it particularly suitable for operational scenarios requiring bidirectional constant speed or mirror-image motion. The gear and rack structure boasts high load-bearing capacity and low wear; combined with precision bearings and a sealed lubrication design, it can operate stably for extended periods.

[0071] In some embodiments, the second connecting member 4 is a housing, and the transmission gear 303 is supported on the second connecting member 4 by bearings to ensure smooth meshing and reduce wear. A position sensor can also be integrated at the gear shaft end to achieve precise feedback and control of the motion stroke.

[0072] Example 4

[0073] This embodiment discloses a pistonless hydraulic system, including the pistonless hydraulic cylinder described in any one of embodiments 1 to 3.

[0074] Specifically, a pistonless hydraulic system includes a pistonless hydraulic cylinder, an oil pump, a control valve, and actuators. The hydraulic cylinder is connected to the control valve via an oil circuit. The control valve regulates the flow and pressure of the hydraulic oil to achieve the reciprocating motion of the hydraulic cylinder.

[0075] The pistonless hydraulic system of this embodiment effectively prevents internal leakage of the hydraulic cylinder by using a pistonless hydraulic cylinder, thereby improving the stability and energy efficiency of the system operation; at the same time, it reduces maintenance costs and extends the service life of the equipment; it also allows for various combinations or arrangements of the first hydraulic module 1 and the second hydraulic module 2 of the hydraulic cylinder, which not only facilitates the flexible piping of the hydraulic system, but also flexibly adapts to the needs of various application scenarios.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A piston-less sealed hydraulic cylinder characterized by, The hydraulic cylinder module comprises a first hydraulic cylinder module (1) and a second hydraulic cylinder module (2), the first hydraulic cylinder module (1) comprises a first cylinder body (11) and a first hydraulic cylinder (12), the second hydraulic cylinder module (2) comprises a second cylinder body (21) and a second hydraulic cylinder (22), and the first hydraulic cylinder (12) and the second hydraulic cylinder (22) can move synchronously in the first cylinder body (11) and the second cylinder body (21) respectively.

2. The piston-less sealed hydraulic cylinder of claim 1, wherein, A first cavity (111) is arranged between the inner wall of the first cylinder body (11) and the first hydraulic cylinder (12), and a second cavity (211) is arranged between the inner wall of the second cylinder body (21) and the second hydraulic cylinder (22).

3. The piston-less sealed hydraulic cylinder of claim 2, wherein, The first cavity (111) and the second cavity (211) are both closed cavities.

4. The piston-less sealed hydraulic cylinder of claim 3, wherein, Gaps are arranged between the outer walls of the first hydraulic cylinder (12) and the second hydraulic cylinder (22) and the inner walls of the first cylinder body (11) and the second cylinder body (21) respectively.

5. The piston-less sealed hydraulic cylinder of claim 4, wherein, The center lines of the first cylinder body (11) and the second cylinder body (21) are parallel.

6. The piston-less sealed hydraulic cylinder of claim 5, wherein, First guide sealing assembly A (113) and second guide sealing assembly A (213) are arranged at the first ends of the first cylinder body (11) and the second cylinder body (21) respectively.

7. The piston-less sealed hydraulic cylinder of claim 6, wherein, First guide sealing assembly A (113) and second guide sealing assembly A (213) are arranged at the first ends of the first cylinder body (11) and the second cylinder body (21) respectively.

8. The piston-less sealed hydraulic cylinder of claim 1, wherein, The first cylinder body (11) and the second cylinder body (21) are fixedly connected through the second connecting piece (4).

9. The piston-less sealed hydraulic cylinder of claim 8, wherein, The first cylinder body (11) and the second cylinder body (21) further comprise first oil port (112) and second oil port (212) respectively, and the first oil port (112) and the second oil port (212) alternately enter and exit oil.

10. A pistonless sealed hydraulic system characterized by, The hydraulic cylinder module comprises an oil pump, a control valve, an execution element and the hydraulic cylinder without piston seal in any one of claims 1 to 9.

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