Synchronous telescopic double-acting two-stage hydraulic cylinder

Abstract

The utility model relates to the technical field of hydraulic telescopic cylinders, and mainly discloses a synchronous telescopic double-acting two-stage hydraulic cylinder which comprises a cylinder barrel, a rear end cover, a large gland, a large piston, a large piston rod, a small piston, a small piston rod and a small gland, the large piston is arranged in the cylinder barrel, the small piston is arranged in the large piston rod, a first-stage rodless cavity is formed between the large piston and the rear end cover, and a second-stage rodless cavity is formed between the large piston and the small gland. A second-stage rodless cavity is formed between the large piston and the small piston, a one-way valve assembly is arranged between the first-stage rodless cavity and the second-stage rodless cavity, a first-stage rod cavity is formed between the inner wall of the cylinder barrel and the outer wall of the large piston rod, and a second-stage rod cavity is formed between the inner wall of the large piston rod and the outer wall of the small piston rod. The first-stage rod cavity is communicated with the second-stage rodless cavity, an oil return cavity is formed in the small piston rod, the oil return cavity is communicated with the oil return port, the second-stage hydraulic cylinder can stretch out and draw back synchronously, in addition, part of components are made of titanium alloy, and light weight and compactness of the hydraulic cylinder are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic telescopic cylinders, in particular to a synchronous telescopic double-acting two-stage hydraulic cylinder. Background Art

[0002] The two-stage telescopic hydraulic cylinder is widely used in hydraulic systems, especially for mechanical transmissions that perform high-power, high-speed, long-stroke, and high-load conditions. The two-stage telescopic hydraulic cylinder is usually composed of two cylinders, one of which is the main cylinder and the other is the auxiliary cylinder. The main cylinder and the auxiliary cylinder are connected in the middle, and each of the main cylinder and the auxiliary cylinder is equipped with a piston connected to the telescopic rod. The piston of the main cylinder is directly connected to the hydraulic pump, and the piston is driven to move by the high-pressure hydraulic oil of the pump. When the piston of the main cylinder pushes the telescopic rod to a certain position, the oil in the oil pipe connected to the auxiliary cylinder gradually flows into the auxiliary cylinder, thereby driving the piston in the auxiliary cylinder to move, achieving a two-stage telescopic effect.

[0003] The two-stage telescopic hydraulic cylinder is mainly divided into two types: single-acting two-stage hydraulic cylinder and double-acting two-stage hydraulic cylinder. The internal structure of the single-acting two-stage hydraulic cylinder is relatively simple, and it has only one oil inlet, which also serves as an oil return port. When the oil is inletted, the cylinder barrels and piston rods of each stage of the single-acting two-stage hydraulic cylinder extend step by step, but it can only provide a unidirectional force and needs to rely on external force (such as load gravity) to achieve retraction. The two-stage cylinder barrels of the double-acting two-stage hydraulic cylinder are provided with oil inlets and outlets to control the movement of each stage of the cylinder barrel. The existing double-acting two-stage hydraulic cylinder can refer to a double-acting two-stage hydraulic cylinder disclosed in Chinese utility model patent CN105650059A.

[0004] The existing technology has the following technical problems: First, when the double-acting two-stage hydraulic cylinder is extended, the large stage is extended first, and after it is in place, the small stage is extended; when it is retracted, the opposite is true. This design that cannot be extended or retracted at the same time leads to slow lifting and lowering speeds, reducing work efficiency. Secondly, the oil return port of the existing two-stage telescopic cylinder is set on the first-stage cylinder body, the second-stage cylinder body or the telescopic rod. This design causes the oil circuit to occupy additional space and is not conducive to installation. Finally, the existing oil cylinder design usually uses common carbon steel materials such as 20# and 45#. Although in order to minimize the volume, HSG standard style hydraulic cylinders are used, some special industries have higher requirements for the compactness, lightweight, aesthetics, corrosion resistance and efficiency of the two-stage telescopic cylinder, and the existing two-stage telescopic cylinder cannot meet these requirements. Utility Model Content

[0005] The purpose of the utility model is to provide a synchronous telescopic double-acting two-stage hydraulic cylinder to solve the technical problems in the prior art that the two-stage telescopic cylinder is not synchronously extended or retracted, and the existing two-stage telescopic cylinder is large in size, occupies a large space, is not conducive to installation and has poor corrosion resistance.

[0006] The technical solution of the utility model to achieve the above-mentioned purpose is a synchronous telescopic double-acting two-stage hydraulic cylinder, comprising a cylinder barrel, a rear end cover, a large pressure cover, a large piston, a large piston rod, a small piston, a small piston rod and a small pressure cover. The rear end cover and the large pressure cover are respectively sealed and connected to the two ends of the cylinder barrel, and the rear end cover is provided with an oil inlet and an oil return port. The large piston is slidably and sealably connected in the cylinder barrel. The large piston rod is hollow inside, and the rear end of the large piston rod is fixedly connected to the large piston. A small pressure cover is provided at the front end of the large piston rod, and the large piston rod is slidably and sealably connected to the large pressure cover and extends out of the front end of the large pressure cover. The small piston is slidably and sealably connected to the inside of the large piston rod, and the rear end of the small piston rod is fixedly connected to the small piston, and the front end of the small piston rod is slidably and sealably connected to the small pressure cover and extends out of the front end of the small pressure cover. There is a primary rodless chamber between the large piston and the rear end cover, the oil inlet is connected to the primary rodless chamber, there is a secondary rodless chamber between the large piston and the small piston, and a one-way valve assembly is provided between the primary rodless chamber and the secondary rodless chamber for unidirectional communication from the primary rodless chamber to the secondary rodless chamber. There is a primary rod chamber between the inner wall of the cylinder and the outer wall of the large piston rod, there is a secondary rod chamber between the inner wall of the large piston rod and the outer wall of the small piston rod, the volumes of the primary rod chamber and the secondary rodless chamber are equal, and the primary rod chamber and the secondary rodless chamber are connected through the first oil port. An oil return chamber is provided inside the small piston rod, the oil return chamber is connected to the secondary rod chamber through the second oil port, the front sliding seal of the large oil pipe is connected to the inside of the small piston rod, the rear end of the large oil pipe is fixedly connected to the large piston, the front end of the small oil pipe is slidably connected to the inside of the large piston and the large oil pipe, the rear end of the small oil pipe is sealed and fixed on the rear end cover, and the oil return chamber is connected to the oil return port through the large oil pipe and the small oil pipe.

[0007] Through the above technical scheme, a one-way valve assembly is set between the first-level rodless chamber and the second-level rodless chamber, the first-level rodless chamber and the second-level rodless chamber are designed to have equal volumes, and the first-level rodless chamber and the second-level rodless chamber are connected. When extending, the first-level rodless chamber extends first, and at the same time, the return oil of the first-level rodless chamber directly enters the second-level rodless chamber, so that the large piston extends while the small piston extends synchronously; when retracting, the oil inlet of the second-level rodless chamber retracts first, and at the same time, the return oil of the second-level rodless chamber enters the first-level rodless chamber, so that the large piston retracts synchronously. The one-way valve assembly allows the medium to fill the primary rodless chamber and the secondary rodless chamber during the initial test and the first action of the two-stage hydraulic cylinder. When the oil is returned, the one-way valve works to prevent the return oil from the secondary rodless chamber from entering the primary rodless chamber and directly entering the primary rod chamber, thereby realizing the function of synchronous extension and retraction. In addition, by connecting the secondary rod chamber with the return oil chamber in the small piston rod, and conducting the return oil of the return oil chamber through the large oil pipe and the small oil pipe to the return oil port of the rear end cover, instead of setting the return oil port at the top of the large piston rod and the small piston rod, the oil inlet and the oil return port are both on the rear end cover at the bottom, which is convenient for installing the oil circuit, thereby saving installation space.

[0008] A further solution of the utility model is that the two ends of the cylinder are respectively connected to the rear end cover and the large gland by threads, and thread-proof sealant is provided at the threaded connection. A second O-ring and a second retaining ring are provided in sequence from front to back between the cylinder and the rear end cover, and a second retaining ring and a second O-ring are provided in sequence from front to back between the cylinder and the large gland, and the second O-ring and the second retaining ring are provided on the outer wall of the rear end cover and the large gland.

[0009] A further solution of the utility model is that the large piston and the cylinder are sealed by a first grid ring and first holes on both sides of the first grid ring with guide strips, and the first grid ring and the first hole guide strips are arranged on the outer wall of the large piston. The small piston and the large piston rod are sealed by a second grid ring and a second hole guide strip, and the two second hole guide strips are respectively located on both sides of the second grid ring.

[0010] A further solution of the utility model is that the large piston rod is connected to the large piston by a thread, the large piston rod is connected to the small gland by a thread, and a thread anti-loosening sealant is provided at the threaded connection. A spacer is provided outside the connection between the large piston rod and the large piston, and the large piston rod and the large gland are sealed from front to back in sequence by a second shaft seal and a second shaft guide belt, two second shaft guide belts are provided, and the second shaft seal and the second shaft guide are provided on the inner wall of the large gland.

[0011] A further solution of the utility model is that the small piston rod is connected to the small piston by a threaded connection, and the small piston rod is connected to the small gland by a threaded connection, and a thread-proof sealant is provided at the threaded connection. The small piston rod and the small piston are sealed by a third O-ring, which is arranged on the outer wall of the small piston rod. The small piston rod and the small gland are sealed by a first shaft seal and a first shaft guide band from front to back, and the first shaft seal and the first shaft guide band are arranged on the inner wall of the small gland. The small gland and the large piston rod are sealed by a first retaining ring and a first O-ring from front to back, and the first retaining ring and the first O-ring are arranged on the outer wall of the small gland.

[0012] A further solution of the utility model is that the large piston and the small oil pipe are sealed from back to front in sequence by a sealing gland and a first shaft Gly ring, the sealing gland and the first shaft Gly ring are arranged on the inner wall of the large piston, the small piston and the large oil pipe are sealed by a second shaft Gly ring, the second shaft Gly ring is arranged on the inner wall of the small piston. The small oil pipe is connected to the rear end cover by threads, thread sealant is applied to the threaded connection, the small oil pipe and the rear end cover are sealed by a fourth O-ring, and the fourth O-ring is arranged on the outer wall of the small oil pipe.

[0013] Through the above technical solution, the sealing and corrosion resistance of the secondary hydraulic cylinder are guaranteed by various seals. The selection of the Gly ring achieves good sealing while having a good guiding function and reducing the friction between components.

[0014] A further solution of the utility model is that the one-way valve assembly includes a one-way valve core, a spring and a screw plug. The large piston has an opening, and the end of the opening close to the rear end cover is a tapered hole. The one-way valve core is installed in the opening, and the tapered surface of the one-way valve core cooperates with the tapered hole. A screw plug is installed in the opening away from the end of the rear end cover, and the screw plug has a central opening. A spring is arranged between the screw plug and the one-way valve core, and the spring presses the one-way valve core.

[0015] A further solution of the utility model is that the cylinder barrel, rear end cover, large gland, large piston, large piston rod, small piston, small piston rod, small gland, small oil pipe, large oil pipe and sealing gland are all made of TC4 material. By selecting TC4 material for each component, the material has good mechanical properties, is more durable, has stronger ultra-high pressure resistance, and has better anti-corrosion effect. At the same time, the volume of the secondary hydraulic cylinder can be reduced, the mass is small, and the space occupied is small, which is suitable for some special needs.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] 1. The utility model sets a one-way valve assembly between the first rodless chamber and the second rodless chamber. The one-way valve assembly allows the medium to fill the first rodless chamber and the second rodless chamber during the initial test and the first action of the second hydraulic cylinder. When the oil is returned, the one-way valve works to prevent the return oil of the second rodless chamber from entering the first rodless chamber and directly entering the first rod chamber, thereby realizing the function of synchronous extension and retraction. The first rod chamber and the second rodless chamber are designed to have equal volumes, and the first rod chamber and the second rodless chamber are connected, so that the two stages of the second cylinder can be extended and retracted at the same time during the extension and retraction process, shortening the extension and retraction time by about 50%, improving work efficiency, and at the same time, there is no jamming during synchronous extension and retraction operation, the driving equipment is more stable during operation, and it is safer and more reliable to use.

[0018] 2. The utility model connects the secondary rod chamber with the oil return chamber in the small piston rod, and conducts the return oil of the oil return chamber to the oil return port of the rear end cover through a large oil pipe and a small oil pipe. The oil inlet and the oil return port are both arranged on the rear end cover at the bottom, which is convenient for installing the oil circuit, thereby saving installation space.

[0019] 3. The utility model not only realizes the "lightweight" of the two-stage hydraulic cylinder and significantly reduces the overall weight by selecting titanium alloy TC4 high-strength alloy material for some components, but also ensures that its structural strength is not affected. In addition, the use of titanium alloy also helps to achieve the "compact" design of the hydraulic cylinder. Due to its high strength and good corrosion resistance, a more compact and lightweight hydraulic cylinder structure can be designed without the need for excessive materials to provide the necessary support and protection. This compact design not only reduces space occupancy, but also improves the flexibility and portability of the hydraulic cylinder, making it more suitable for various complex and narrow installation environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the utility model 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 only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a schematic diagram of the overall structure of the booster cylinder in Example 1 of the utility model;

[0022] Figure 2 For this utility model Figure 1 A schematic diagram of the enlarged structure in the middle.

[0023] In the figure: 1, cylinder barrel, 2, rear end cover, 3, small oil pipe, 4, large piston rod, 5, large piston, 6, large pressure cover, 7, small piston rod, 8, small piston, 9, small pressure cover, 10, large oil pipe, 11, spacer, 12, sealing pressure cover 12, 13, one-way valve core, 14, screw plug, 15, first shaft seal, 16, first O-ring, 17, first retaining ring, 18, first shaft guide belt, 19, second shaft seal, 20, second O-ring, 21, second retaining ring, 22, second shaft guide belt , 23. First grid ring, 24. Guide strip for first hole, 25. Second grid ring, 26. Guide strip for second hole, 27. Third O-ring, 28. Grid ring for first shaft, 29. Grid ring for second shaft, 30. Fourth O-ring, 31. Spring, 32. Oil inlet, 33. Oil return port, 34. First-stage rodless cavity, 35. First-stage rod cavity, 36. Second-stage rodless cavity, 37. Second-stage rod cavity, 38. Oil return cavity, 39. First oil port, 40. Second oil port, 41. Through hole. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] In the present invention, "front", "back", "inside" and "outside" only represent relative position relationships. When the absolute position of the described object changes, the relative position relationship may also change accordingly.

[0026] Example 1

[0027] like Figure 1-2 As shown, the right side in the accompanying drawings is the relative front end, and the left side is the relative rear end.

[0028] A synchronous telescopic double-acting two-stage hydraulic cylinder comprises a cylinder barrel 1, a rear end cover 2, a large gland 6, a large piston 5, a large piston rod 4, a small piston 8, a small piston rod 7 and a small gland.

[0029] The large pressure cover 6 and the rear end cover 2 are respectively sealed and connected to the front and rear ends of the cylinder 1. Specifically, the cylinder 1 is cylindrical, and the two ends of the cylinder 1 are respectively connected to the rear end cover 2 and the large pressure cover 6 by threads, and thread anti-loosening sealant is provided at the threaded connection. A second O-ring 20 and a second retaining ring 21 are sequentially provided from front to back between the rear end of the cylinder 1 and the rear end cover 2, and a second retaining ring 21 and a second O-ring 20 are sequentially provided from front to back between the front end of the cylinder 1 and the large pressure cover 6. The second O-ring 20 and the second retaining ring 21 are provided on the outer walls of the rear end cover 2 and the large pressure cover 6.

[0030] The rear end cover 2 is provided with an oil inlet 32 ​​and an oil return port 33, and the oil inlet 32 ​​and the oil return port are arranged on the outer wall of the rear end cover 2. The large piston 5 is connected to the cylinder 1 in a sliding seal, the large piston rod 4 is hollow inside, one end of the large piston rod 4 is fixedly connected to the large piston 5, and the other end of the large piston rod 4 is provided with a small gland 9, and the large piston rod is connected to the large gland 6 in a sliding seal and extends out of the front end of the large gland 6. Specifically, the large piston 5 is sealed with the cylinder 1 by a first grid ring 23 and a first hole guide belt 24, and the two first hole guide belts 24 are respectively located on both sides of the first grid ring 23, and the first grid ring 23 and the first hole guide belt 24 are arranged on the outer wall of the large piston 5; the small piston 8 is sealed with the large piston rod 4 by a second grid ring 25 and a second hole guide belt 26, and the two second hole guide belts 26 are respectively located on both sides of the second grid ring 25, and the second grid ring 25 and the second hole guide belt 26 are arranged on the outer wall of the small piston 8. The large piston rod 4 is connected to the large piston 5 by a thread, and the large piston rod 4 is connected to the small pressure cover 9 by a thread. The threaded connection is provided with a thread anti-loosening sealant. The outside of the connection between the large piston rod 4 and the large piston 5 is provided with a spacer sleeve 11. The large piston rod 4 and the large pressure cover 6 are sealed from front to back in sequence by the second shaft seal 19 and the second shaft guide belt 22. Two second shaft guide belts 22 are arranged at intervals. The second shaft seal 19 and the second shaft guide are arranged on the inner wall of the large pressure cover 6.

[0031] The small piston 8 is connected to the inside of the large piston rod 4 in a sliding seal, one end of the small piston rod 7 is fixedly connected to the small piston 8, and the other end of the small piston rod 7 is connected to the small gland 9 in a sliding seal and extends out of the large piston rod 4. Specifically, the small piston rod 7 is connected to the small piston 8 by a thread, and the small piston rod 7 is connected to the small gland 9 by a thread, and a thread anti-loosening sealant is provided at the threaded connection. The small piston rod 7 and the small piston 8 are sealed by a third O-ring 27, and the third O-ring 27 is arranged on the outer wall of the small piston rod 7. The small piston rod 7 and the small gland 9 are sealed from front to back in sequence by the first shaft seal 15 and the first shaft guide belt 18. Two first shaft guide belts 18 are arranged at intervals, and the first shaft seal 15 and the first shaft guide belt 18 are arranged on the inner wall of the small gland 9. The small gland 9 and the large piston rod 4 are sealed from front to back in sequence by the first retaining ring 17 and the first O-ring 16, and the first retaining ring 17 and the first O-ring 16 are arranged on the outer wall of the small gland 9.

[0032] There is a primary rodless chamber 34 between the large piston 5 and the rear end cover 2, the oil inlet 32 ​​is connected to the primary rodless chamber 34, there is a secondary rodless chamber 36 between the large piston 5 and the small piston 8, and a one-way valve assembly is provided between the primary rodless chamber 34 and the secondary rodless chamber 36, which conducts one-way from the primary rodless chamber 34 to the secondary rodless chamber 36. Specifically, the one-way valve assembly includes a one-way valve core 13, a spring 31 and a screw plug 14. A through hole 41 is provided on the large piston 5, and the rear end of the through hole 41 is a tapered hole. The one-way valve core 13 is installed in the tapered hole, and the tapered surface at the rear end of the one-way valve core 13 matches the tapered hole. A screw plug 14 is installed at the front end of the through hole 41, and the center of the screw plug 14 is opened. A spring 31 is provided between the screw plug 14 and the one-way valve core 13, and the spring 31 presses the one-way valve core 13. When filled with medium for the first time, when the hydraulic oil reaches a certain pressure, the hydraulic oil pushes the one-way valve core 13 to move to the front end. At this time, the gap between the conical surface of the one-way valve core 13 and the conical hole of the through hole 41 opens, the one-way valve assembly opens, and the hydraulic oil enters from the gap between the one-way valve core 13 and the conical hole of the through hole 41, and then flows into the secondary rodless chamber 36 from the central opening of the screw plug 14; when the hydraulic oil rush is closed, the spring 31 makes the one-way valve core 13 move to the rear end, the conical surface of the one-way valve core 13 fits tightly with the conical hole of the through hole 41, and the gap between the conical surface of the one-way valve core 13 and the conical hole of the through hole 41 is closed, so that the one-way valve assembly is closed. Therefore, the hydraulic oil in the secondary rodless chamber cannot enter the primary rodless chamber 34 at the rear end from the central opening of the screw plug 14.

[0033] The first rod chamber 35 is between the inner wall of the cylinder 1 and the outer wall of the large piston rod 4, and the second rod chamber 37 is between the inner wall of the large piston rod 4 and the outer wall of the small piston rod 7. The first rod chamber 35 and the second rodless chamber 36 have the same volume, and the first rod chamber 35 and the second rodless chamber 36 are connected through the first oil port 39, which is arranged at the rear end of the large piston rod 4 near the large piston 5. Figure 1As shown, the small piston rod 7 is provided with an oil return chamber 38 inside, and the oil return chamber 38 is connected with the secondary rod chamber 37 through the second oil port 40, and the second oil port 40 is arranged on the small piston rod 7 near the small piston 8. One end of the large oil pipe 10 is connected to the inside of the small piston rod 7 by sliding sealing, and the rear end of the large oil pipe 10 is fixedly connected with the large piston 5. The front end of the small oil pipe 3 is connected to the inside of the large piston 5 and the large oil pipe 10 by sliding, and the rear end of the small oil pipe 3 is sealed and fixed on the rear end cover 2, and the oil return chamber 38 is connected with the oil return port 33 through the large oil pipe 10 and the small oil pipe 3. The large piston 5 and the small oil pipe 3 are sealed from the outside to the inside in turn by the sealing gland 12 and the first shaft Gly ring 28, and the sealing gland 12 and the first shaft Gly ring 28 are arranged on the inner wall of the large piston 5. The small piston 8 and the large oil pipe 10 are sealed by the second shaft Gly ring 29, and the second shaft Gly ring 29 is arranged on the inner wall of the small piston 8. The small oil pipe 3 is connected to the rear end cover 2 by threads, and thread sealant is applied to the threaded connection. The small oil pipe 3 and the rear end cover 2 are sealed by the fourth O-ring 30, and the fourth O-ring 30 is set on the outer wall of the small oil pipe 3. The secondary rod chamber 37 is connected with the oil return chamber 38 in the small piston rod 7, and the return oil of the oil return chamber 38 is conducted to the oil return port of the rear end cover 2 through the large oil pipe 10 and the small oil pipe 3. The oil inlet 32 ​​and the oil return port 33 are both on the rear end cover 2 at the bottom, which is convenient for installing the oil circuit, thereby saving installation space.

[0034] The first grid ring 23, the first hole guide belt 24, the second grid ring 25, the second hole guide belt 26, the first shaft grid ring 28, the second shaft grid ring 29, the first shaft guide belt 18, and the second shaft guide belt 22 are all prior art and are well known to those skilled in the art. The grid ring is a seal made of a rubber O-ring and polytetrafluoroethylene material. It has low friction, high pressure resistance and a wide range of temperature adaptability. Contact stress is generated through its elastic deformation, thereby effectively preventing liquid leakage. The grid ring is widely used in many fields such as petrochemicals, aerospace, etc., and is regarded as an indispensable component in the field of industrial sealing. The grid ring is a bidirectional seal and is often used for piston sealing. The hole guide belt, also known as the hole guide ring, is an important sealing and guiding component in equipment such as hydraulic cylinders or cylinders. Its main function is to support the movement of the piston or piston rod to prevent it from direct contact with the cylinder body and wear. This kind of guide belt has the characteristics of wear resistance, low friction, heat resistance and strong chemical stability, and is usually made of PTFE, NBR, PU, ​​POM, PA and other materials. The shaft guide belt, also known as the shaft guide ring, is a part of the sealing product. It mainly plays a guiding role, can prevent wear between the cylinder and the piston rod, and absorb vibration. It is extremely wear-resistant, has a low friction coefficient, and is heat-resistant and chemically resistant. It is widely used in motion management mechanisms such as oil cylinders and cylinders to ensure the stability of bearings and extend the service life of equipment.

[0035] Through the above technical solution, the synchronous telescopic function of the secondary hydraulic cylinder is realized. The specific method is to set a one-way valve assembly between the primary rodless chamber 34 and the secondary rodless chamber 36, and at the same time design the primary rod chamber 35 and the secondary rodless chamber 36 to have equal volumes and be connected to each other. When extending, the primary rodless chamber 34 extends first, and at this time, the return oil of the primary rod chamber 35 directly enters the secondary rodless chamber 36, so that the large piston 5 and the small piston 8 can be extended synchronously. When retracting, the secondary rod chamber 37 retracts first, and at the same time, the return oil of the secondary rodless chamber 36 enters the primary rod chamber 35, so that the large piston 5 can retract synchronously. During the initial experiment and the first action of this secondary hydraulic cylinder, the one-way valve assembly ensures that the medium can fill the primary rodless chamber 34 and the secondary rodless chamber 36. When returning oil, the one-way valve can prevent the return oil of the secondary rodless chamber 36 from entering the primary rodless chamber 34 and then directly entering the primary rod chamber 35, thereby realizing the synchronous telescopic function of the secondary hydraulic cylinder.

[0036] A further solution of the utility model is that the cylinder barrel 1, the rear end cover 2, the large gland 6, the large piston 5, the large piston rod 4, the small piston 8, the small piston rod 7, the small gland 9, the small oil pipe 3, the large oil pipe 10 and the sealing gland 12 are all made of TC4 material. By selecting the material of each component as TC4 material, not only the "lightweight" of the two-stage hydraulic cylinder is achieved, the overall weight is significantly reduced, but also its structural strength is ensured to be unaffected. This is because titanium alloy has excellent specific strength (i.e., the ratio of strength to density), which means that even while reducing weight, the bearing capacity of the component can be maintained or improved. In addition, the use of titanium alloy also helps to achieve the "compact" design of the hydraulic cylinder. Due to its high strength and good corrosion resistance, a more compact and lightweight hydraulic cylinder structure can be designed without the need for too much material to provide the necessary support and protection. This compact design not only reduces space occupancy, but also improves the flexibility and portability of the hydraulic cylinder, making it more suitable for various complex and narrow installation environments.

[0037] Example 2

[0038] This embodiment is based on the embodiment 1, and is different from the embodiment 1 in that an oil return port 33 can be directly set on the small pressure cover 9, and the secondary rod chamber 37 is connected to the oil return port 33 on the small pressure cover 9, or an oil return chamber 38 is set in the small piston rod 7, and the secondary rod chamber 37 is connected to the oil return chamber 38 through the second oil port 40, and an oil return port 33 is set on the small piston rod 7, and the oil return chamber 38 is connected to the oil return port 33. Both methods can also achieve synchronous extension and retraction.

[0039] The assembly process of the two-stage hydraulic cylinder of the utility model is as follows: first, install the sealing components. Next, install the small oil pipe 3 on the rear end cover 2, install the large oil pipe 10 and the large piston rod 4 on the large piston 5, and install the small piston rod 7 on the small piston 8. Subsequently, install the rear end cover 2 and the small oil pipe 3 assembly at the rear end of the cylinder barrel 1, install the large oil pipe 10, the large piston rod 4 and the large piston 5 assembly in the cylinder barrel 1, and then fix the large piston rod 4 with the large gland 6. Finally, install the small piston rod 7 and the small piston 8 assembly in the small piston rod 7, and then fix the small piston rod 7 with the small gland 9.

[0040] After the assembly is completed, first, the medium is filled. Hydraulic oil is filled into the first-level rodless chamber 34 through the oil inlet 32, and the large piston 5 moves to the front end. When the hydraulic oil in the first-level rodless chamber 34 reaches a certain pressure, the one-way valve assembly is unidirectionally conducted, and the hydraulic oil enters the second-level rodless chamber 36 from the first-level rodless chamber 34. The small piston 8 moves to the front end. Since the second-level rodless chamber 36 is connected to the first-level rod chamber 35, at the same time, the hydraulic oil also enters the first-level rod chamber 35. The air in the second-level rod chamber 37 enters the return oil chamber 38 from the second oil port 40 and is discharged through the return oil port 33. Then, hydraulic oil is filled into the return oil chamber 38 through the return oil port 33, and the hydraulic oil enters the return oil chamber 38 in the small piston rod 7 from the small oil pipe 3 and the large oil pipe 10. The hydraulic oil in the return oil chamber 38 enters the secondary rod chamber 37 from the second oil port 40, filling the secondary rod chamber 37 with hydraulic oil. At the same time, the small piston 8 moves toward the rear end. Since the one-way valve is closed, the hydraulic oil in the secondary rodless chamber 36 enters the primary rod chamber 35, driving the large piston 5 to move toward the rear end, and the hydraulic oil in the primary rodless chamber 34 returns to the hydraulic system from the oil inlet 32, thereby completing the initial medium filling experiment.

[0041] When in use, when extending, the first-level rodless chamber 34 extends first, and at the same time, the return oil of the first-level rod chamber 35 directly enters the second-level rodless chamber 36, so that when the large piston 5 is extended, the small piston 8 is also extended synchronously; when retracting, the second-level rod chamber 37 takes oil, the small piston 8 retracts first, and at the same time, the return oil of the second-level rodless chamber 36 enters the first-level rod chamber 35, so that the large piston 5 is retracted synchronously.

[0042] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

Claims

1. A synchronous telescopic double-acting two-stage hydraulic cylinder, characterized in that: The invention comprises a cylinder barrel (1), a rear end cover (2), a large pressure cover (6), a large piston (5), a large piston rod (4), a small piston (8), a small piston rod (7) and a small pressure cover (9), wherein the rear end cover (2) and the large pressure cover (6) are respectively sealedly connected to the two ends of the cylinder barrel (1), the rear end cover (2) is provided with an oil inlet (32) and an oil return port (33), the large piston (5) is slidably sealedly connected to the cylinder barrel (1), the large piston rod (4) is hollow inside, the rear end of the large piston rod (4) is fixedly connected to the large piston (5), and the front end of the large piston rod (4) is fixedly connected to the large piston (5). A small pressure cover (9) is provided at the end portion, the large piston rod (4) is connected to the large pressure cover (6) in a sliding and sealing manner and extends out of the front end of the large pressure cover (6), the small piston (8) is connected to the inside of the large piston rod (4) in a sliding and sealing manner, the rear end of the small piston rod (7) is fixedly connected to the small piston (8), the front end of the small piston rod (7) is connected to the small pressure cover (9) in a sliding and sealing manner and extends out of the front end of the small pressure cover (9), a first-stage rodless chamber (34) is formed between the large piston (5) and the rear end cover (2), the oil inlet (32) is connected to the first-stage rodless chamber (34), the large piston (5) and the small piston (8) are connected to each other, and the oil inlet (32) is connected to the first-stage rodless chamber (34). ) is a secondary rodless chamber (36), a one-way valve assembly is provided between the primary rodless chamber (34) and the secondary rodless chamber (36) for unidirectional communication from the primary rodless chamber (34) to the secondary rodless chamber (36), a primary rod chamber (35) is provided between the inner wall of the cylinder barrel (1) and the outer wall of the large piston rod (4), a secondary rod chamber (37) is provided between the inner wall of the large piston rod (4) and the outer wall of the small piston rod (7), the volumes of the primary rod chamber (35) and the secondary rodless chamber (36) are equal, and the primary rod chamber (35) and the secondary rodless chamber (36) are connected via a first oil port (39). The small piston rod (7) is provided with an oil return chamber (38) inside, and the oil return chamber (38) is connected with the secondary rod chamber (37) through the second oil port (40). The front of the large oil pipe (10) is slidingly and sealingly connected to the inside of the small piston rod (7), and the rear end of the large oil pipe (10) is fixedly connected to the large piston (5). The front end of the small oil pipe (3) is slidingly connected to the inside of the large piston (5) and the large oil pipe (10), and the rear end of the small oil pipe (3) is sealed and fixed on the rear end cover (2). The oil return chamber (38) is connected with the oil return port (33) through the large oil pipe (10) and the small oil pipe (3).

2. A synchronous telescopic double-acting two-stage hydraulic cylinder according to claim 1, characterized in that: The two ends of the cylinder barrel (1) are respectively connected to the rear end cover (2) and the large gland (6) through threads, and the cylinder barrel (1) and the rear end cover (2) as well as the cylinder barrel (1) and the large gland (6) are sealed by a second retaining ring (21) and a second O-ring (20).

3. A synchronous telescopic double-acting two-stage hydraulic cylinder according to claim 2, characterized in that: The large piston (5) and the cylinder (1) are sealed by a first grid ring (23) and the first holes on both sides of the first grid ring (23) using guide strips (24); the small piston (8) and the large piston rod (4) are sealed by a second grid ring (25) and the second hole using guide strips (26).

4. A synchronous telescopic double-acting two-stage hydraulic cylinder according to claim 3, characterized in that: The large piston rod (4) and the large piston (5) are connected via threads, the large piston rod (4) and the small gland (9) are connected via threads, a spacer (11) is provided outside the connection between the large piston rod (4) and the large piston (5), and the large piston rod (4) and the large gland (6) are sealed via a second shaft seal (19) and a second shaft guide belt (22).

5. A synchronous telescopic double-acting two-stage hydraulic cylinder according to claim 4, characterized in that: The small piston rod (7) and the small piston (8) are connected by threads, the small piston rod (7) and the small pressure cover (9) are connected by threads, the small piston rod (7) and the small piston (8) are sealed by a third O-ring (27), the small piston rod (7) and the small pressure cover (9) are sealed by a first shaft seal (15) and a first shaft guide belt (18); the small pressure cover (9) and the large piston rod (4) are sealed by a first retaining ring (17) and a first O-ring (16).

6. The synchronous telescopic double-acting two-stage hydraulic cylinder according to claim 5, characterized in that: The large piston (5) and the small oil pipe (3) are sealed by a sealing gland (12) and a first shaft using a Gly ring (28), the small piston (8) and the large oil pipe (10) are sealed by a second shaft using a Gly ring (29), the small oil pipe (3) and the rear end cover (2) are connected by threads, and the small oil pipe (3) and the rear end cover (2) are sealed by a fourth O-ring (30).

7. A synchronous telescopic double-acting two-stage hydraulic cylinder according to any one of claims 1 to 6, characterized in that: The one-way valve assembly comprises a one-way valve core (13), a spring (31) and a screw plug (14). The one-way valve core (13), the spring (31) and the screw plug (14) are sequentially installed in the through hole of the large piston (5) from back to front, and the spring (31) presses the one-way valve core (13).

8. A synchronous telescopic double-acting two-stage hydraulic cylinder according to any one of claims 1 to 6, characterized in that: The cylinder barrel (1), rear end cover (2), large gland (6), large piston (5), large piston rod (4), small piston (8), small piston rod (7), small gland (9), small oil pipe (3), large oil pipe (10) and sealing gland (12) are all made of TC4 material.

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