Combined seal structure and hydraulic cylinder

Abstract

The present application relates to the technical field of sealing structure, and especially relates to a combined sealing structure and hydraulic cylinder, which comprises a gap seal between mounting surfaces, a first sealing element, a first retainer ring, a first elastic element, a second retainer ring, a second sealing element, a retainer ring, a second elastic element and a plug; the first sealing element is arranged between the gap seal and the first retainer ring, the first retainer ring and the second retainer ring are connected through the first elastic element, the second sealing element is arranged between the second retainer ring and the retainer ring, and the second retainer ring is connected with the plug through the second elastic element. The combined sealing structure provided by the present application can bear fluid pressure through the first sealing element and the second sealing element, so that the damage and failure of the sealing element are avoided, and the overall performance of the sealing system is improved; through the arrangement of the first elastic element and the second elastic element, the pressure fluctuation and pressure impact are buffered, most of the pressure is borne by the gap seal with high strength, a small part of the pressure is borne by the first sealing element, and the overall performance of the sealing system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sealing structure, in particular to a combined sealing structure and hydraulic cylinder. BACKGROUND

[0002] The sealing device is a crucial component in mechanical equipment working in a fluid environment, which can effectively control the leakage of medium and ensure the safe operation of the mechanical structure while maintaining its normal operation. Gap sealing is a common non-contact mechanical seal, which relies on the close fit between the piston and the inner wall of the cylinder or the shaft and the inner wall of the cylinder to form a very small gap between them to achieve sealing and ensure the pressure difference between the two cavities. It is generally used in conditions with high speed, high vibration frequency and large pressure impact. Gap sealing has the advantages of fast response speed, high structural strength and long service life. However, gap sealing has the problems of large leakage and insufficient sealing effect. The sealing structure of rubber and plastic sealing and spring energy storage sealing is commonly used in the mechanical field. The installation groove and the sealing element are assembled with interference, and the initial pre-tightening force is provided by the spring or the deformation of the rubber to form a contact pressure on the sealing surface to achieve sealing. However, the sealing element material is soft and has low strength, and the viscoelastic properties of the rubber material will produce hysteresis effect. When the sealing element faces high speed, high vibration frequency and large pressure impact conditions, the sealing structure will be damaged and the hysteresis effect will cause sealing failure. SUMMARY

[0003] The present application provides a combined sealing structure and hydraulic cylinder to solve the defects of sealing structure damage and hysteresis effect leading to sealing failure when the sealing element faces high speed, high vibration frequency and large pressure impact conditions in the prior art.

[0004] The present application provides a combined sealing structure arranged between a first mounting surface and a second mounting surface.

[0005] The combined sealing structure comprises a gap sealing, a first sealing element, a first retainer ring, a first elastic element, a second retainer ring, a second sealing element, a retainer ring, a second elastic element and a plug between the first mounting surface and the second mounting surface.

[0006] One end of the plug is arranged on the first mounting surface, the other end is arranged between the first mounting surface and the second mounting surface and away from the gap sealing, the first sealing element is arranged between the gap sealing and the first retainer ring, one end of the first retainer ring and the second retainer ring is connected by the first elastic element, the second sealing element is arranged between one end of the second retainer ring and the retainer ring, the retainer ring is arranged on the other end of the plug, the other end of the second retainer ring is connected to the other end of the plug by the second elastic element.

[0007] The second sealing member is in a gap fit with the first mounting surface and / or the second mounting surface in a natural state.

[0008] The first sealing member comprises a Y-shaped rubber ring, one end of the Y-shaped rubber ring is provided with a groove type structure, the groove type structure is arranged towards the direction of the gap sealing, and a cavity is formed between the groove type structure and the gap sealing.

[0009] The second blocking ring comprises a T-shaped blocking ring, the head of the T-shaped blocking ring is arranged on the stepped surface of the first mounting surface, the rod of the T-shaped blocking ring sequentially passes through the second sealing member and the blocking ring and is connected with the second elastic member.

[0010] The other end of the plug is formed with a mounting groove, the second elastic member is arranged in the mounting groove, the rod of the T-shaped blocking ring extends into the mounting groove and is connected with the mounting groove through the second elastic member.

[0011] The second sealing member comprises:

[0012] A first O-shaped sealing ring is arranged between the rod of the T-shaped blocking ring and the first mounting surface;

[0013] A second O-shaped sealing ring is arranged between the rod of the T-shaped blocking ring and the second mounting surface.

[0014] The blocking ring comprises:

[0015] A first O-shaped plastic blocking ring is arranged between the rod of the T-shaped blocking ring and the first mounting surface;

[0016] A second O-shaped plastic blocking ring is arranged between the rod of the T-shaped blocking ring and the second mounting surface.

[0017] The combination sealing structure further comprises a locking member, one end of the plug is formed with an assembly hole, the locking member passes through the assembly hole to fix the plug on the first mounting surface.

[0018] The combination sealing structure further comprises a gasket, the gasket is sleeved on the locking member and is arranged between one end of the plug and the first mounting surface.

[0019] The first elastic member and the second elastic member are both pressure springs.

[0020] The application further provides a hydraulic cylinder comprising the combined sealing structure.

[0021] The combined sealing structure comprises a gap seal between the first mounting surface and the second mounting surface, a first sealing element, a first retainer ring, a first elastic element, a second retainer ring, a second sealing element, a retainer ring, a second elastic element and a plug. One end of the plug is arranged on the first mounting surface, and the other end is arranged between the first mounting surface and the second mounting surface and away from the gap seal. The first sealing element is arranged between the gap seal and the first retainer ring. One end of the first retainer ring and the second retainer ring is connected by the first elastic element. The second sealing element is arranged between one end of the second retainer ring and the retainer ring. The retainer ring is arranged on the other end of the plug. The other end of the second retainer ring is connected to the other end of the plug by the second elastic element. The second sealing element is in clearance fit with the first mounting surface and / or the second mounting surface in a natural state. The combined sealing structure can share the fluid pressure by the first sealing element and the second sealing element, avoid damage and failure of the sealing element due to excessive pressure, and improve the overall performance of the sealing system. The first elastic element and the second elastic element can buffer pressure fluctuations and pressure shocks. The gap seal with high strength can bear most of the pressure, and the first sealing element can bear a small part of the pressure, thereby improving the overall performance of the sealing system. The second sealing element can ensure that the gas or liquid passes between the first retainer ring and the second retainer ring in a natural state, thereby ensuring that the first sealing element and the first retainer ring have sufficient displacement space.

[0022] Further, the application further provides a hydraulic cylinder. Since the hydraulic cylinder comprises the combined sealing structure in the embodiments of the application, the hydraulic cylinder has the same advantages as described above. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creative effort.

[0024] Figure 1 is a structure schematic view of the combined sealing structure provided in one of the embodiments of the application and arranged between a piston and a cylinder barrel.

[0025] Figure 2 is a structure schematic view of the combined sealing structure provided in one of the embodiments of the application and arranged between a shaft and a cylinder barrel.

[0026] Figure 3is a structure schematic view of the combined sealing structure provided in one embodiment of the present application installed between the piston and the cylinder when the spring is fully compressed.

[0027] Reference signs:

[0028] 1: piston; 2: cylinder; 3: gap seal; 4: first seal; 5, first retainer ring; 6: first elastic member; 7: second retainer ring; 8: first O-ring; 9: second O-ring; 10: first O-shaped plastic retainer ring; 11: second O-shaped plastic retainer ring; 12: second elastic member; 13: plug; 14: gasket; 15: locking member. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below with reference to the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0030] In the description of the present embodiment, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present embodiment and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present embodiment.

[0031] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present embodiment, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0032] In this embodiment, unless otherwise specified or limited, the terms "disposed," "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, or integration; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this embodiment based on specific circumstances.

[0033] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0034] The following combination Figures 1-3 The invention describes a combined sealing structure, which is arranged between a first mounting surface and a second mounting surface and is used for sealing the first mounting surface and the second mounting surface in a hydraulic cylinder or a gas cylinder.

[0035] The combined sealing structure includes: a gap seal 3 between the first mounting surface and the second mounting surface, a first sealing member 4, a first retaining ring 5, a first elastic member 6, a second retaining ring 7, a second sealing member, a retaining ring, a second elastic member 12 and a plug 13.

[0036] Specifically, one end of the plug 13 is arranged on the first mounting surface, and the other end is arranged between the first mounting surface and the second mounting surface, and is arranged away from the gap seal 3. The first seal 4 is arranged between the gap seal 3 and the first retaining ring 5. The first retaining ring 5 and one end of the second retaining ring 7 are connected through the first elastic member 6. The second seal is arranged between one end of the second retaining ring 7 and the retaining ring. The retaining ring is arranged at the other end of the plug 13. The other end of the second retaining ring 7 is connected to the other end of the plug 13 through the second elastic member 12. In the natural state, the second seal is gap-fitted with the first mounting surface and / or the second mounting surface.

[0037] like Figure 1 In the structure shown, the gap seal 3, the first seal 4, the first retaining ring 5, the first elastic member 6, the second retaining ring 7, the second seal, the retaining ring, the second elastic member 12 and the plug 13 between the first mounting surface and the second mounting surface are arranged in sequence from small to large along the gap between the first mounting surface and the second mounting surface.

[0038] The upper side of the first mounting surface is a high-pressure cavity. When pressure fluctuation occurs, the fluid pressure in the high-pressure cavity suddenly rises. The hydraulic oil in the high-pressure cavity will leak through the gap seal 3 between the first mounting surface and the second mounting surface to the cavity above the first seal 4. When the cavity is filled with oil, the first seal 4 and the first retainer 5 move downward under the action of fluid pressure, the first elastic member 6 is compressed, and the volume of the cavity above the first seal 4 increases. During the above process, since the volume of the cavity above the first seal 4 is variable, the high pressure generated by the pressure fluctuation is borne by the gap seal 3 and cannot be directly transmitted to the first seal 4. The pressure borne by the first seal 4 depends on the elastic force of the first elastic member 6, i.e. P=F / S, where P is the fluid pressure, F is the elastic force of the first elastic member 6, and S is the pressure receiving area of the first seal 4 in the vertical direction. The variable volume of the cavity above the first seal 4 is achieved by a mechanical structure, and is used in cooperation with the gap seal 3 to achieve the buffering of pressure fluctuation and pressure impact. The gap seal 3 with high strength bears most of the pressure, and the first seal 4 bears a small part of the pressure, thereby improving the overall performance of the sealing system.

[0039] The second seal is assembled on the inner side and / or the outer side of the first retainer 5. In the natural state, i.e. when the second elastic member 12 is not compressed, there is no interference between the second seal and the second mounting surface and / or the first mounting surface, i.e. there is a gap between the second seal and the second mounting surface and / or a gap between the second seal and the first mounting surface. The purpose of the above-mentioned gap is to allow the stored fluid or gas between the second retainer 7 and the first retainer 5 to pass through the gap when the first seal 4 and the first retainer 5 move downward under the action of fluid pressure, thereby ensuring that the first seal 4 and the first retainer 5 have sufficient displacement space.

[0040] When the high pressure of the pressure fluctuation lasts for a long time, the first seal 4 and the first retainer 5 continue to move downward, the first elastic member 6 is completely compressed, and at the same time the first retainer 5 and the second retainer 7 come into contact, thereby causing the second retainer 7 to move downward, the second elastic member 12 is compressed, and the second seal is compressed, and the gap between the second seal and the second mounting surface and / or the first mounting surface disappears. At this time, the first seal 4 and the second seal form a series sealing system, in which the fluid pressure is borne by the first seal 4 and the second seal together, thereby avoiding damage and failure of the seal caused by excessive pressure and improving the overall performance of the sealing system, i.e. the structure as shown in Figure 3 It can be seen that the variable compression amount of the second seal is achieved by the combination of the second retainer 7 and the elastic member. In the low pressure working condition, the second seal does not participate in sealing (the structure as shown in Figure 1 In the high pressure working condition, the second seal and the first seal 4 form a series sealing system (the structure as shown in Figure 3 ).

[0041] As shown in Figure 1 the first mounting surface can be on the piston 1 in the hydraulic cylinder or pneumatic cylinder, and the second mounting surface can be on the cylinder barrel 2 in the hydraulic cylinder or pneumatic cylinder, which can be used for sealing the piston 1; as shown in Figure 2 the first mounting surface can be on the shaft in the hydraulic cylinder or pneumatic cylinder, and the second mounting surface can be on the cylinder barrel 2 in the hydraulic cylinder or pneumatic cylinder, which can be used for sealing the shaft.

[0042] The combined sealing structure provided by the application is arranged between the first mounting surface and the second mounting surface, and comprises a gap seal 3 between the first mounting surface and the second mounting surface, a first sealing element 4, a first retainer ring 5, a first elastic element 6, a second retainer ring 7, a second sealing element, a retainer ring, a second elastic element 12 and a plug 13. One end of the plug 13 is arranged on the first mounting surface, the other end is arranged between the first mounting surface and the second mounting surface and is arranged away from the gap seal 3. The first sealing element 4 is arranged between the gap seal 3 and the first retainer ring 5. One end of the first retainer ring 5 and the second retainer ring 7 is connected through the first elastic element 6. The second sealing element is arranged between one end of the second retainer ring 7 and the retainer ring. The retainer ring is arranged on the other end of the plug 13. The other end of the second retainer ring 7 is connected to the other end of the plug 13 through the second elastic element 12. The second sealing element is in clearance fit with the first mounting surface and / or the second mounting surface in a natural state. The combined sealing structure provided by the application can bear fluid pressure through the first sealing element 4 and the second sealing element, so as to avoid damage and failure of the sealing element due to excessive pressure and improve the overall performance of the sealing system. Through the arrangement of the first elastic element 6 and the second elastic element 12, the pressure fluctuation and pressure impact are buffered. Most of the pressure is borne by the gap seal 3 with high strength, and a small part of the pressure is borne by the first sealing element 4, so as to improve the overall performance of the sealing system. In the natural state, the second sealing element can ensure that the gas or liquid passes between the first retainer ring 5 and the second retainer ring 7, so as to ensure that the first sealing element 4 and the first retainer ring 5 have enough displacement space.

[0043] In one embodiment of the application, the first sealing element 4 comprises a Y-shaped rubber ring. One end of the Y-shaped rubber ring has a groove structure, which is arranged in the direction of the gap seal 3 and forms a cavity between the groove structure and the gap seal 3. When the first mounting surface generates pressure fluctuation, the fluid pressure in the high-pressure cavity suddenly rises, and the hydraulic oil in the high-pressure cavity leaks into the groove structure and the cavity on the upper part of the Y-shaped rubber ring (the space on the upper part of the Y-shaped rubber ring) through the gap seal 3. When the oil fills the groove structure and the cavity, the Y-shaped rubber ring and the first retainer ring 5 are moved downward under the action of fluid pressure, the first elastic element 6 is compressed, and the volume of the cavity on the upper part of the Y-shaped rubber ring is increased.

[0044] Optionally, the first blocking ring 5 can be a metal blocking ring, which is connected with the second blocking ring 7 through the first elastic member 6 and is located at the bottom of the Y-shaped rubber ring.

[0045] In one embodiment of the present application, the second blocking ring 7 comprises a T-shaped blocking ring, the head of the T-shaped blocking ring is arranged on the stepped surface of the first mounting surface, and the stem of the T-shaped blocking ring passes through the second sealing member and the blocking ring in sequence and is connected with the second elastic member 12. Specifically, the T-shaped blocking ring comprises a head and a stem, the radial dimension of the head is greater than that of the stem, and the axial dimension of the head is smaller than that of the stem. The second elastic member 12 is connected between the head of the T-shaped blocking ring and the first blocking ring 5, and the head of the T-shaped blocking ring is clamped on the stepped surface of the first mounting surface to limit the upward displacement thereof. Under the pressure of the high-pressure liquid, the first blocking ring 5 compresses the first elastic member 6, so that the T-shaped blocking ring moves downward, and at the same time, the second elastic member 12 is compressed.

[0046] In one embodiment of the present application, the other end of the plug 13 is formed with a mounting groove, the second elastic member 12 is arranged in the mounting groove, and the stem of the T-shaped blocking ring extends into the mounting groove and is connected with the mounting groove through the second elastic member 12. In this embodiment, the plug 13 is in an L-shaped structure and is arranged on the stepped surface of the first mounting surface. A mounting groove is processed on the upper end surface of the plug 13, the second elastic member 12 is arranged in the mounting groove, the stem of the T-shaped blocking ring extends into the mounting groove and is connected with the second elastic member 12, and when the T-shaped blocking ring descends, the second elastic member 12 is compressed.

[0047] In one embodiment of the present application, the second sealing member comprises a first O-shaped sealing ring 8 and a second O-shaped sealing ring 9. The first O-shaped sealing ring 8 is arranged between the stem of the T-shaped blocking ring and the first mounting surface, and the second O-shaped sealing ring 9 is arranged between the stem of the T-shaped blocking ring and the second mounting surface. In this embodiment, the second sealing member comprises O-shaped sealing rings arranged on the inner and outer sides of the stem of the T-shaped blocking ring, so that gaps are formed between the T-shaped blocking ring and the first mounting surface and between the T-shaped blocking ring and the second mounting surface, which ensures that the gas or liquid stored between the first blocking ring 5 and the second blocking ring 7 can pass through the two gaps in a natural state, and ensures that the first sealing member 4 and the first blocking ring 5 have sufficient displacement space.

[0048] In one embodiment of the present application, the blocking ring comprises a first O-shaped plastic blocking ring 10 and a second O-shaped plastic blocking ring 11. The first O-shaped plastic blocking ring 10 is arranged between the stem of the T-shaped blocking ring and the first mounting surface, and the second O-shaped plastic blocking ring 11 is arranged between the stem of the T-shaped blocking ring and the second mounting surface. In this embodiment, the blocking ring also comprises O-shaped plastic blocking rings arranged on the inner and outer sides of the stem of the T-shaped blocking ring, which are arranged correspondingly with the O-shaped sealing rings on the inner and outer sides.

[0049] In one of the embodiments of the present application, the combined sealing structure further comprises a locking member 15; one end of the plug 13 is formed with an assembly hole, and the locking member 15 passes through the assembly hole to fix the plug 13 on the first mounting surface. Preferably, the locking member 15 can be a bolt, and a threaded hole is formed on the first mounting surface, and the plug 13 is fixed on the first mounting surface by the bolt passing through the assembly hole and cooperating with the threaded hole on the first mounting surface.

[0050] In one of the embodiments of the present application, the combined sealing structure further comprises a gasket 14, which is sleeved on the locking member 15 and arranged between one end of the plug 13 and the first mounting surface. In this embodiment, the gasket 14 is arranged between the contact surface of the plug 13 and the first mounting surface, so as to avoid damaging the contact surface of the first mounting surface by the plug 13 and ensure the safety of the hydraulic cylinder.

[0051] In one of the embodiments of the present application, the first elastic member 6 and the second elastic member 12 are both pressure springs. Of course, other elastic members with the same function can also be used instead.

[0052] The present application also provides a hydraulic cylinder. The hydraulic cylinder comprises the combined sealing structure in the embodiments of the present application. Specifically, the combined sealing structure in the embodiments of the present application is arranged between the first mounting surface and the second mounting surface.

[0053] Further, the present application also provides a hydraulic cylinder, which has the same advantages as described above because it comprises the combined sealing structure in the embodiments of the present application.

[0054] The device embodiments described above are only schematic, and the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiments. Those skilled in the art can understand and implement without creative labor.

[0055] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A combined sealing structure, characterized in that: Located between the first mounting surface and the second mounting surface; The combined sealing structure comprises: a gap seal (3) between the first mounting surface and the second mounting surface, a first sealing member (4), a first retaining ring (5), a first elastic member (6), a second retaining ring (7), a second sealing member, a retaining ring, a second elastic member (12) and a plug (13); One end of the plug (13) is arranged on the first mounting surface, and the other end is arranged between the first mounting surface and the second mounting surface and is arranged away from the gap seal (3); the first seal (4) is arranged between the gap seal (3) and the first retaining ring (5); the first retaining ring (5) and one end of the second retaining ring (7) are connected through the first elastic member (6); the second seal is arranged between one end of the second retaining ring (7) and the retaining ring; the retaining ring is arranged at the other end of the plug (13); the other end of the second retaining ring (7) is connected to the other end of the plug (13) through the second elastic member (12); In a natural state, the second sealing member is in clearance fit with the first mounting surface and / or the second mounting surface.

2. The combined sealing structure according to claim 1, characterized in that: The first sealing member (4) comprises a Y-shaped rubber ring, one end of the Y-shaped rubber ring having a groove structure, the groove structure being arranged in the direction of the gap seal (3), and forming a chamber between the groove structure and the gap seal (3).

3. The combined sealing structure according to claim 1, characterized in that: The second retaining ring (7) comprises a T-shaped retaining ring, the head of the T-shaped retaining ring being arranged on the step surface of the first mounting surface, the rod of the T-shaped retaining ring passing through the second sealing member and the retaining ring in sequence and being connected to the second elastic member (12).

4. The combined sealing structure according to claim 3, characterized in that: The other end of the plug (13) is formed with a mounting groove, the second elastic member (12) is arranged in the mounting groove, and the rod portion of the T-shaped retaining ring extends into the mounting groove and is connected to the mounting groove through the second elastic member (12).

5. The combined sealing structure according to claim 3, characterized in that: The second sealing member comprises: a first O-type sealing ring (8), the first O-type sealing ring (8) being arranged between the stem portion of the T-type retaining ring and the first mounting surface; A second O-type sealing ring (9) is provided between the rod portion of the T-type retaining ring and the second mounting surface.

6. The combined sealing structure according to claim 3, characterized in that: The retaining ring comprises: a first O-shaped plastic retaining ring (10), the first O-shaped plastic retaining ring (10) being arranged between the stem portion of the T-shaped retaining ring and the first mounting surface; A second O-shaped plastic retaining ring (11) is provided between the rod portion of the T-shaped retaining ring and the second mounting surface.

7. The combined sealing structure according to any one of claims 1 to 6, characterized in that: Also includes: A locking member (15); an assembly hole is formed at one end of the plug (13); the locking member (15) passes through the assembly hole to fix the plug (13) on the first mounting surface.

8. The combined sealing structure according to claim 7, characterized in that: Also includes: A gasket (14), the gasket (14) is sleeved on the locking member (15) and is arranged between one end of the plug (13) and the first mounting surface.

9. The combined sealing structure according to any one of claims 1 to 6, characterized in that: The first elastic member (6) and the second elastic member (12) are both pressure springs.

10. A hydraulic cylinder, characterized in that: include: The combined sealing structure according to any one of claims 1 to 9.

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