A sequence telescopic oil cylinder and a control valve thereof

Abstract

The application discloses a sequence telescopic oil cylinder and a control valve thereof, wherein four oil ports of T, P, A and B are arranged at the head of a piston rod, and a stroke control valve and a spring self-resetting rod valve core are arranged on the four oil ports; when the valve core is popped out, A and B are unidirectionally communicated; when the valve core is compressed, A and B are bidirectionally communicated; B is connected with T; the bottom of the piston is provided with oil communication diameters one, two and three, which are respectively connected with A, T and P; the head and the bottom of the cylinder barrel are respectively provided with oil ports T1 and P1; T1 is connected with the inside of the cylinder barrel through two rows of small holes of the cylinder barrel; P1 is connected with the inside of the cylinder barrel; the bottom of the cylinder barrel is provided with a core pipe two, the front end of which is open and connected with a core pipe one, and the tail thereof is connected with P1 through a one-way valve. The application realizes sequence telescopic movement, and the oil in the rod cavity only needs to be imported and exported through the stroke control valve in the full extension to the end or the full extension to the initial stage; the small holes of the cylinder barrel play the role of pilot oil way, effectively reduce the size of the loop structure, and reduce the problems of high back pressure and large heat generation caused by poor oil import and export, and are suitable for the folding arm crane industry.

Description

Technical Field

[0001] This invention relates to the field of hydraulic lifting equipment technology, specifically to a sequential telescopic cylinder and its control valve. Background Technology

[0002] In hydraulic lifting equipment, the internal oil circuits of the cylinder, piston rod, and stroke control valve are usually designed to achieve the extension and retraction control of the cylinder through the action of the hydraulic oil circuit.

[0003] However, existing sequential telescopic cylinders and their control valve solutions have shortcomings. For example, patent "A Sequential Cylinder with Oil Inlet Control 201922294276.6" designs a first oil port that communicates with the rodless chamber of the cylinder, an oil pipe that communicates with the second flow channel hole, a first one-way valve between the oil pipe and the rodless chamber, and a second one-way valve between the third and fourth flow channel holes, thus completing the sequential extension action of two cylinders connected in series. Patent "A Sequential Cylinder with Hydraulic Controlled One-Way Valve 202021813366.8" includes a hydraulic controlled one-way valve, with the first one-way valve oil port connected to the fourth oil port through the second one-way valve oil port, etc. This structure does not cause excessive back pressure on the return oil of the rod chamber. However, both of the above solutions can only achieve sequential extension of the cylinders.

[0004] Patent "A Sequential Hydraulic Cylinder Anti-Disorder Sealing Structure 202123235722.X" provides a sealing structure for preventing disordered operation of a sequential hydraulic cylinder. It features a cylinder bottom movable sleeve screwed together with the cylinder bottom, a bidirectional V-shaped seal between the main piston and the auxiliary main piston, a buffer plunger connected to the auxiliary piston via a ball bearing, and a core tube located inside the oil guide pipe, the other end of which pulls the valve core within the combination valve. This solution enables sequential extension and retraction, but the cylinder needs to retract a small section before stopping and sequential retraction can be achieved. The stroke control valve is located at the bottom of the cylinder, making it unsuitable for use in the articulated boom crane industry.

[0005] Patent "Valve Core Sealing Structure, Valve and Sequential Cylinder 202023211346.6" designs a valve core sealing structure, including a valve core, push rod, and seals, to achieve valve closure and thus sequential extension and retraction of the cylinder. Patent "A Sequential Cylinder 201520861241.5" designs a multi-layer piston rod to achieve sequential extension and retraction using a series connection. However, in both of these solutions, the oil in the rod chamber of the cylinder must return through the set control valve, which can easily lead to poor oil inlet and return, resulting in problems such as high back pressure and high heat generation.

[0006] Therefore, how to achieve completely continuous sequential extension and retraction of tandem hydraulic cylinders, ensure that the installation position of the stroke control valve is suitable for the articulated boom crane industry, and prevent issues such as poor oil inlet and outlet leading to high back pressure and excessive heat generation remains an urgent problem to be solved. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the existing defects and provide a sequential telescopic hydraulic cylinder and its control valve. By adopting a specific stroke control valve structure, combined with the design of the internal components and oil circuit of the hydraulic cylinder, the hydraulic cylinder can achieve completely continuous sequential telescopic movement. Furthermore, the installation position of the stroke control valve is suitable for the articulated boom crane industry, and it is not easy to have problems such as high back pressure and high heat generation caused by poor oil inlet and outlet. This solves the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A sequential telescopic hydraulic cylinder includes a cylinder barrel and a piston rod. One end of the piston rod is equipped with a stroke control valve, and the other end is equipped with a piston, which is installed inside the cylinder barrel.

[0010] The piston rod head is provided with four oil ports: T, P, A, and B. The B oil port is connected to the T oil port through an internal oil passage in the piston rod head.

[0011] The stroke control valve has two oil ports, A1 and B1, which are connected to oil ports A and B respectively. A one-way valve is provided between oil ports A1 and B1. A spring self-resetting lever valve core is provided on one side of the stroke control valve. Normally, it is in the popped-out state. When the spring self-resetting lever valve core pops out, the oil flows from oil port A to oil port B in a one-way communication. When the spring self-resetting lever valve core is compressed, the oil ports A and B are connected in a two-way communication through the valve core.

[0012] All piston rods are provided with core tube one and core tube three, with core tube three on the outside and core tube one on the inside, and there is a gap between core tube three and core tube one;

[0013] The piston has three oil passages at the bottom, including oil passage one, oil passage two, and oil passage three;

[0014] The A port of the stroke control valve is connected to the oil passage diameter one through the gap between the core tube three and the core tube one.

[0015] The B port of the stroke control valve is connected to the T port through the internal oil passage of the stroke control valve; the T port is connected to the oil passage through the internal cavity of the piston rod and the internal oil passage of the piston.

[0016] The P port of the stroke control valve is connected to the internal space of the core tube and is connected to the oil passage diameter three at the bottom of the piston through the core tube.

[0017] The cylinder includes a cylinder head and a cylinder bottom, which are respectively provided with oil ports T1 and P1; the oil port T1 at the cylinder head is connected to the internal space of the cylinder through two rows of small holes on the cylinder.

[0018] A second core tube is installed at the bottom of the cylinder. The second core tube has an open front end and a closed rear end. The diameter of the second core tube is smaller than that of the first core tube, and it can be inserted into the first core tube during the movement of the piston rod. The second core tube has two oil passage holes on its wall, including an oil passage hole one at the front and an oil passage hole two near the rear.

[0019] The oil passage hole one is located so that it will only be exposed from the bottom of the piston when the piston rod is fully extended from inside the cylinder, connecting the internal space of the rodless chamber of the cylinder with the internal space of the core tube two.

[0020] The P1 oil port at the bottom of the cylinder is connected to the internal space of the cylinder through the inner oil passage at the bottom of the cylinder; at the same time, the P1 oil port is connected to the oil passage at the tail of the core tube II through the inner oil passage at the bottom of the cylinder. The oil passage between the P1 oil port and the oil passage II is equipped with a one-way valve II that only allows liquid to flow from the inside of the core tube II through the oil passage II to the P1 oil port.

[0021] The oil passages of oil passage one, oil passage two, and oil passage three are isolated by a seal; the piston is equipped with a seal to isolate the oil passages between the rod chamber and the rodless chamber of the cylinder; the oil passage two at the tail of the core tube two is equipped with a seal to isolate the oil passages from the internal space of the cylinder.

[0022] Further detailed design is as follows:

[0023] The T and P ports of the stroke control valve are located in front of the rod head, while the A and B ports are located on top of the rod head.

[0024] Both core tube one and core tube three are welded to the rod head.

[0025] A seal is provided between the outlet of oil passage one and the outlet of oil passage two on the outer wall of the piston; a seal is provided on the inner wall of the piston near the internal cavity of the piston rod to isolate the oil passage between oil passage one and the internal cavity of the piston; a seal is provided on the inner wall of the piston away from the internal cavity of the piston rod to isolate the oil passage between oil passage three and the internal cavity of the piston rod; a seal is provided at the end of the piston, which is a combined seal to isolate the oil passage between the rod chamber and the rodless chamber of the cylinder.

[0026] The oil passage hole at the tail of the core tube is provided with a seal five, which consists of a sealing ring at the front and rear of the oil passage hole two, thereby isolating the oil passage hole two from the oil passage inside the cylinder.

[0027] The T1 oil port at the head of the cylinder is connected to the internal space of the cylinder through two rows of small holes on the cylinder. The two rows of small holes include a front row of small holes and a rear row of small holes, which are located within the inner diameter of the T1 oil port pipe, and there are 5 small holes in each row.

[0028] The second core tube is fixed at one end of the bottom of the cylinder and is installed by threads.

[0029] The stroke control valve includes a valve body with two oil ports, A1 and B1. Two parallel oil passages are provided between the two oil ports A1 and B1 within the valve body. One oil passage has a one-way valve to prevent oil flow from B1 to A1, allowing flow only from A1 to B1. The other oil passage has a spring-loaded self-resetting lever valve core, which is normally in the pop-out state and has a normally open valve core oil passage. When the spring-loaded self-resetting lever valve core is popped out, the valve core oil passage is inactive. When the spring-loaded self-resetting lever valve core is compressed, bidirectional communication is achieved between the two oil ports A1 and B1 through the valve core oil passage.

[0030] The working principle of this invention is as follows: The sequential telescopic cylinder of this invention is connected in series with a multi-stage cylinder. The intermediate stage cylinder is a sequential telescopic cylinder with the same structure as this invention, and the last stage is a regular cylinder. The T1 and P1 oil ports on the cylinder barrel of the sequential telescopic cylinder are connected to a multi-way valve, and the T and P oil ports on the rod head are respectively connected to the T1' and P1' oil ports on the cylinder barrel of the next stage cylinder.

[0031] Sequential extension process: The oil pump supplies oil to the P1 port of the sequential extension cylinder through the multi-way valve. The oil enters the cylinder from the bottom oil passage and pushes the cylinder forward. Before the oil passage 1 on the front wall of the core tube 2 at the bottom of the cylinder protrudes from the bottom of the core tube piston, no oil enters the next stage cylinder, and the next stage cylinder remains stationary. When the sequential extension cylinder is fully extended, the oil passage 1 protrudes from the bottom of the piston, and the oil enters the ordinary cylinder through the oil passage 1 to achieve sequential extension.

[0032] The sequential retraction process is as follows: Oil enters the internal cavity of the piston rod through the T1 port of the sequential telescopic cylinder and the second oil passage on the piston, and then enters the T1' port of the next stage cylinder through the T port of the rod head, pushing the piston rod of the next stage cylinder to retract. During this process, no oil enters the rod chamber of the sequential telescopic cylinder, so the sequential telescopic cylinder remains stationary. After the next stage cylinder has fully retracted, the mechanical impact block that follows the movement of the sequential telescopic cylinder strikes the stroke control valve push rod of the rod head of the sequential telescopic cylinder, connecting the B1 port to the A1 port, and then connecting the B port of the rod head to the A port. Oil enters the internal cavity of the piston rod through the second oil passage on the piston, then enters the B port of the rod head to the A port, enters the core tube three through the internal oil passage of the rod head, and enters the rod chamber of the sequential telescopic cylinder through the first oil passage on the piston, pushing the sequential telescopic cylinder to retract.

[0033] During the sequential extension process described above, in the initial stage of cylinder extension, the oil in the rod chamber returns directly to the oil tank through two rows of small holes on the cylinder wall. Critical state: When the seal between oil passages one and two on the piston moves to the space between the two rows of small holes on the cylinder wall, the oil in the rod chamber continues to return through the front row of small holes, while the rear row of small holes connects to oil passage two on the piston. As the cylinder continues to extend, when the front row of small holes on the cylinder wall is above the seal between oil passages one and two, the oil in the rod chamber enters the stroke control valve of the rod head through the core tube three, and then enters the piston rod cavity through the one-way valve one, returning to the oil tank through oil passage two on the piston and the rear row of small holes on the cylinder wall. Therefore, in the critical state, the two rows of small holes on the cylinder wall provide an uninterrupted return loop, allowing the cylinder to extend continuously.

[0034] During the above-mentioned sequential extension process, the seal between the first and second oil passages on the piston can directly supply oil to the rod chamber after passing through the small holes at the front row below the oil port T1 of the cylinder, increasing the oil passage efficiency and reducing the problem of excessive temperature rise caused by poor oil passage.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. The stroke control valve of this invention is installed at the piston rod head and is applicable to the articulated boom crane industry;

[0037] 2. In this invention patent, the oil in the rod chamber of the cylinder only needs to enter and return through the stroke control valve in the initial stage and at the end of the extension. After one of the two rows of small holes on the cylinder runs to the left side of the seal between the first and second oil passages, the oil can directly enter and return.

[0038] 3. The hydraulic cylinder of the present invention can achieve strict sequential extension and retraction, and the oil needs to enter and exit through the core tube and stroke control valve only when the hydraulic cylinder is fully extended to the end or in the initial stage of full extension and retraction. This is equivalent to a pilot oil circuit, which effectively reduces the structural size of the circuit and the problems of high back pressure and high heat generation caused by poor oil entry and exit. Attached Figure Description

[0039] Figure 1 A schematic diagram of the hydraulic cylinder and stroke control valve in the retracted state;

[0040] Figure 2 for Figure 1 Schematic diagram of the structure with the piston rod extended along the MM section;

[0041] Figure 3 for Figure 2 Enlarged view of the piston rod section;

[0042] Figure 4 for Figure 2 Enlarged view of the cylinder head section;

[0043] Figure 5 for Figure 4 Schematic diagram of two rows of small holes in the F direction on the middle cylinder;

[0044] Figure 6 This is a schematic diagram of a stroke control valve.

[0045] Figure 7 for Figure 3 Enlarged view of the piston rod head section, where (b) is a cross-sectional view and (a) is a view of (b) in the E direction;

[0046] Figure 8 for Figure 3 Enlarged view of the bottom of the piston rod;

[0047] Figure 9 for Figure 4 Enlarged view of the head of the cylinder bore;

[0048] Figure 10 for Figure 4 Enlarged view of the bottom of the cylinder head;

[0049] Figure 11 This is a schematic diagram of the sequential telescopic hydraulic cylinder of the present invention connected in series with a conventional hydraulic cylinder;

[0050] Figure 12 for Figure 11 A schematic diagram showing the piston moving to position 1;

[0051] Figure 13 for Figure 11 A schematic diagram showing the piston moving to position 2.

[0052] In the diagram: 1. Sequential telescopic hydraulic cylinder; 2. Ordinary hydraulic cylinder; 3. Cylinder barrel; 4. Piston rod; 5. Stroke control valve; 6. Rod head; 7. Piston; 8. Cylinder barrel head; 9. Cylinder barrel bottom; 10. Front row of small holes; 11. Rear row of small holes; 12. Core tube one; 13. Core tube two; 14. Core tube three; 15. Oil passage hole one; 16. Oil passage hole two; 17. Oil passage diameter one; 18. Oil passage diameter two; 19. Oil passage diameter three; 20. Seal one; 21. Seal two; 22. Seal three; 23. Seal four; 24. Seal five; 25. Valve body; 26. Spring self-resetting lever valve core; 27. Valve core oil passage; 28. Check valve one; 29. ​​Check valve two; 30. Multi-way valve. Detailed Implementation

[0053] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Combination Figure 1-2 As shown, the present invention provides a sequential telescopic hydraulic cylinder 1, including a cylinder 3 and a piston rod 4. A stroke control valve 5 is installed at one end of the piston rod 4, and a piston 7 is provided at the other end, which is installed inside the cylinder 3. The piston rod 4 is fully retracted into the cylinder 3 as shown in the figure. Figure 1 As shown, the piston rod 4 is fully extended out of the cylinder 3 as follows: Figure 2 As shown.

[0055] Combination Figure 1 , 2 As shown in Figures 3, 6, and 7, the piston rod head 6 has four oil ports, namely T, P, A, and B. Among them, oil ports T and P are located at the front of the rod head, and oil ports A and B are located at the top of the rod head. A stroke control valve 5 is installed on the rod head 6, and the stroke control valve 5 has two oil ports, A1 and B1, which are connected to oil ports A and B respectively.

[0056] Combination Figure 3 and Figure 8 As shown, the piston rod 4 is equipped with a core tube 12 and a core tube 3 14. The bottom of the piston is equipped with three oil passages, including an oil passage 17, an oil passage 2 18, and an oil passage 3 19. Core tubes 12 and 3 14 are both welded to the rod head 6, with core tube 3 14 on the outside and core tube 12 on the inside, and there is a gap between core tube 3 14 and core tube 12.

[0057] The A1 port of the stroke control valve 5 and the A port of the rod head 6 are connected to the oil passage 17 through the gap between the core tube 14 and the core tube 12.

[0058] The B1 port of the stroke control valve 5 and the B port of the rod head 6 are connected to the T port through the internal oil passage of the rod head; the T port is connected to the oil passage 18 through the internal cavity of the piston rod and the internal oil passage of the piston.

[0059] The P-port of the rod head 6 is connected to the internal space of the core tube 12, and is connected to the oil passage diameter 319 at the bottom of the piston through the core tube 12.

[0060] A seal 20 is provided between the outlet of oil passage 17 and the outlet of oil passage 18 on the outer wall of piston 7; a seal 21 is provided on the inner wall of piston 7 near the internal cavity of piston rod to isolate the oil passage between oil passage 17 and the internal cavity of piston; a seal 22 is provided on the inner wall of piston 7 away from the internal cavity of piston rod to isolate the oil passage between oil passage 19 and the internal cavity of piston rod; a seal 23 is provided at the end of piston, which is a combined seal to isolate the oil passage between the rod chamber and the rodless chamber of the cylinder.

[0061] Combination Figure 4 , 5As shown in Figures 9 and 10, the cylinder 3 includes a cylinder head 8 and a cylinder bottom 9, which are respectively provided with oil ports T1 and P1. The oil port T1 of the cylinder head 8 communicates with the internal space of the cylinder through two rows of small holes on the cylinder, namely the front row of small holes 10 and the rear row of small holes 11.

[0062] A core tube 13 is threaded onto the bottom 9 of the cylinder. Core tube 13 has an open front and a closed rear. The diameter of core tube 13 is smaller than that of core tube 12, and the outer diameter of core tube 13 matches the inner diameter of core tube 12. Core tube 13 is inserted into core tube 12 through the oil passage 3 at the bottom of the piston. The length of core tube 13 is greater than the cylinder stroke. Two oil passages are formed on the wall of core tube 13: an oil passage 15 at the front and an oil passage 16 near the rear. The oil passage 15 is only exposed at the bottom of the piston when the piston rod is fully extended from inside the cylinder, connecting the rodless chamber of the cylinder with the internal space of core tube 13.

[0063] The oil passage hole 216 at the tail of the core tube 213 is equipped with a seal 5 24. The seal 5 24 consists of a sealing ring at the front and rear of the oil passage hole 216, which isolates the oil passage hole 216 from the internal oil passage of the cylinder and the external space.

[0064] The P1 oil port at the bottom of the cylinder 9 is connected to the internal space of the cylinder through the inner oil passage at the bottom of the cylinder; at the same time, the P1 oil port is connected to the oil passage at the tail of the core tube 13 through the inner oil passage at the bottom of the cylinder. A one-way valve 29 is installed in the oil passage between the P1 oil port and the oil passage 26, which only allows the liquid to flow from the inside of the core tube 13 through the oil passage 26 to the P1 oil port.

[0065] like Figure 6 The diagram shows the principle of a stroke control valve, including a valve body 25. The valve body 25 has two oil ports, A1 and B1, which are connected to an external oil circuit. There are two parallel oil circuits between the two oil ports A1 and B1 in the valve body. One oil circuit has a one-way valve 28, which prevents the oil from flowing from B1 to A1, and only allows flow from A1 to B1. The other oil circuit has a spring self-resetting lever valve core 26, which is normally in the popped-out state, and has a normally open valve core oil circuit 27. When the spring self-resetting lever valve core 26 is popped out, the valve core oil circuit 27 does not function. When the spring self-resetting lever valve core 26 is compressed, the two oil ports A1 and B1 are bidirectionally connected through the valve core oil circuit 27.

[0066] The system includes a valve body 25 with two oil ports, A1 and B1, connected to an external oil circuit. The internal oil circuits of ports A1 and B1 are two parallel circuits: one circuit has a check valve 28, characterized by a non-connection between ports B1 and A1, and a connection between ports A1 and B; the other circuit is a spring-loaded self-resetting valve core circuit, normally open, where ports A1 and B1 are bidirectionally connected when the spring-loaded self-resetting valve core is compressed. Figure 1 , 6 Therefore, when the spring self-resetting lever valve core 26 is in the popped-out state, the oil can only flow from A to B of the lever head; when the spring self-resetting lever valve core 26 is impacted and in the compressed state, the two oil ports A and B of the lever head are fully connected, allowing the oil to flow freely between A and B.

[0067] Working principle of this invention: Figure 11 As shown, taking the sequential telescopic cylinder 1 and the ordinary cylinder 2 connected in series as an example, the T1 and P1 oil ports on the cylinder barrel 3 of the sequential telescopic cylinder 1 are connected to the multi-way valve 30, and the T and P oil ports on the rod head 6 are connected to the T1' and P1' oil ports on the cylinder barrel of the ordinary cylinder 2, respectively. The mechanical structure connected to the ordinary cylinder 2 is equipped with a mechanical stop block. When the ordinary cylinder 2 is fully retracted, the mechanical stop block strikes the spring self-resetting lever valve core push rod of the stroke control valve of the sequential telescopic cylinder 1, so that B1 to A1 are fully connected.

[0068] Sequential extension implementation:

[0069] Oil Inlet Circuit: The oil pump supplies oil to port P1 of the sequential telescopic cylinder 1 through the multi-way valve 30. Oil enters the cylinder from the bottom oil passage, pushing the cylinder forward. The one-way valve between port P1 and core tube 13 prevents oil from entering core tube 13. Before the oil passage 15 on the front wall of core tube 13 at the bottom of the cylinder protrudes from the bottom of the piston, no oil enters the ordinary cylinder 2, and the ordinary cylinder 2 remains stationary. Only when the sequential telescopic cylinder 1 is fully extended, and core tube 13 and piston 7 reach the desired position... Figure 12 As shown, oil passage hole 15 protrudes from the bottom of piston 7. Oil enters the internal space of core tube 13 through oil passage hole 15, and then enters the P1' oil port on the cylinder of ordinary cylinder 2 through core tube 12 and rod head P oil port, so as to realize the extension of ordinary cylinder 2, and thus realize the sequential extension.

[0070] Oil return circuit: During the initial cylinder extension, the oil in the rod chamber returns directly to the oil tank through two rows of small holes on the cylinder wall, namely the front row of small holes 10 and the rear row of small holes 11. Critical state as follows... Figure 13As shown: When the seal between the first oil passage 17 and the second oil passage 18 on the piston 7 moves to the space between the two rows of small holes 10 and 11 on the cylinder wall, the oil in the rod chamber still returns through the front row of small holes, while the rear row of small holes connects to the second oil passage 18 on the piston. The cylinder continues to extend, and when the front row of small holes 10 on the cylinder wall is above the seal between the first oil passage 17 and the second oil passage 18, the oil circuit is interrupted. The oil in the rod chamber enters the core tube 14 through the first oil passage 17, reaches the rod head A port, and then enters the stroke control valve 5 above the rod head. It then enters the piston rod cavity through the one-way valve 28 and returns to the oil tank through the second oil passage 18 on the piston and the rear row of small holes 11 on the cylinder wall. Therefore, in the critical state, the two rows of small holes 10 and 11 on the cylinder wall provide an uninterrupted return circuit, allowing the cylinder to extend continuously.

[0071] Sequential retraction implementation: In this embodiment, two-stage hydraulic cylinders extend sequentially. Here, we simulate the situation where the sequential telescopic hydraulic cylinder 1 has been fully extended and needs to be retracted sequentially.

[0072] Oil inlet circuit: Oil enters the internal cavity of the piston rod through port T1 of the sequential telescopic cylinder 1, and then enters port T1' of the next-stage ordinary cylinder 2 through port T at the rod head, pushing the piston rod of the ordinary cylinder 2 to retract. During this process, the stroke control valve 5 at the rod head controls the spring self-resetting lever valve core 26, which is normally in the pop-out state. The flow from port B1 to port A1 is not connected, and oil cannot enter the rod chamber of the sequential telescopic cylinder 1, thus the sequential telescopic cylinder 1 remains stationary. Only when the ordinary hydraulic cylinder 2 is fully retracted, the mechanical impact block that follows the movement of the ordinary hydraulic cylinder 2 strikes the stroke control valve push rod of the sequential telescopic hydraulic cylinder 1, causing the oil to flow from B1 to A1. The oil then enters the internal cavity of the piston rod through the second oil passage 18 on the piston, then enters the oil port B of the rod head, passes through the internal oil passage of the stroke control valve, goes from B1 to A1, and then to the oil port A of the rod head, entering the gap between the core tube 14 and the core tube 12. Finally, it enters the rod chamber of the sequential telescopic hydraulic cylinder 1 through the first oil passage 17 on the piston, pushing the sequential telescopic hydraulic cylinder 1 to retract. The seal between the first oil passage 17 and the second oil passage 18 on the piston is achieved through the small holes 10 below the oil port T1 of the cylinder barrel, allowing direct oil supply to the rod chamber, increasing oil flow efficiency and reducing the problem of excessive temperature rise caused by poor oil flow.

[0073] Oil return circuit: The oil in the rodless chamber of the ordinary cylinder 2 is connected to the P port of the rod head of the sequential telescopic cylinder 1 through the P1' oil port, enters the internal space of the core tube 12 inside the piston rod of the sequential telescopic cylinder 1, connects to the core tube 13 inside the cylinder, and then returns to the oil tank through the one-way valve 28 at the bottom of the cylinder of the sequential telescopic cylinder 1, which is connected to the P1 oil port.

[0074] The stroke control valve of the present invention is installed at the head of the piston rod, which is more suitable for the articulated boom crane industry compared to the solution where the stroke control valve is installed at the bottom of the cylinder.

[0075] The hydraulic cylinder described in this invention can achieve strictly sequential extension and retraction. The cylinder barrel of the sequential extension cylinder is designed with two rows of small holes for oil circuit conduction in critical states, essentially acting as a pilot oil circuit. The oil in the rod chamber of this section of the cylinder only needs to enter and exit through the core tube 14 and stroke control valve during the full extension to the end or the initial stage of full retraction. Oil can directly enter and exit through the front row of small holes 10 in the F direction on the cylinder barrel after reaching the left side of the seal 20. This design effectively reduces the structural size of the circuit and mitigates problems such as high back pressure and excessive heat generation caused by poor oil inlet and outlet.

[0076] Other embodiments: The present invention realizes the sequential extension and retraction of multi-stage hydraulic cylinders. It only requires the multi-stage hydraulic cylinders to be connected in series according to the method given in the present invention. Each of the first stage is a sequential extension and retraction hydraulic cylinder provided by the present invention, and the last stage is an ordinary hydraulic cylinder. The oil ports T1 and P1 of the first stage sequential extension and retraction hydraulic cylinder are connected to the multi-way valve, and the oil ports T and P of the upper stage are connected to the oil ports T and P of the lower stage, so that the sequential extension and retraction of multi-stage hydraulic cylinders can be realized.

[0077] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sequential telescopic hydraulic cylinder, comprising a cylinder barrel and a piston rod, characterized in that: The piston rod has a stroke control valve installed at one end of its rod head and a piston at the other end, which is installed inside the cylinder. The piston rod head is provided with four oil ports: T, P, A, and B. The B oil port is connected to the T oil port through an internal oil passage in the piston rod head. The stroke control valve includes a valve body with two oil ports, A1 and B1. Oil port A1 is connected to oil port A of the rod head, and oil port B1 is connected to oil port B of the rod head. Two parallel oil circuits are provided between oil ports A1 and B1 within the valve body. One oil circuit has a check valve to prevent oil flow from B1 to A1, allowing flow only from A1 to B1. The other oil circuit has a spring-loaded self-resetting lever valve core, which is normally in the pop-out state and has a normally open valve core oil circuit. When the spring-loaded self-resetting lever valve core is popped out, the valve core oil circuit is inactive. When the spring-loaded self-resetting lever valve core is compressed, bidirectional communication is achieved between oil ports A1 and B1 through the valve core. The piston bottom is provided with oil passage diameter one, oil passage diameter two, and oil passage diameter three; The piston rod is provided with a core tube one and a core tube three, with the core tube three on the outside and the core tube one on the inside, and there is a gap between the core tube three and the core tube one; The A1 port of the stroke control valve is connected to the oil passage diameter one through the gap between the core tube three and the core tube one; The T-port is connected to the oil passage through the internal cavity of the piston rod and the internal oil passage of the piston; The P-port of the piston rod head is connected to the internal space of the core tube and is connected to the oil passage diameter three at the bottom of the piston through the core tube. The cylinder includes a cylinder head and a cylinder bottom, which are respectively provided with oil ports T1 and P1; the T1 oil port of the cylinder head is connected to the internal space of the cylinder through two rows of small holes on the cylinder; the two rows of small holes include a front row of small holes and a rear row of small holes, which are located within the inner diameter of the T1 oil port pipe, and there are 5 small holes in each row. A second core tube is installed at the bottom of the cylinder. The second core tube has an open front end and a closed rear end. The diameter of the second core tube is smaller than that of the first core tube, and it can be inserted into the first core tube during the movement of the piston rod. The second core tube has two oil passage holes on its wall, including an oil passage hole one at the front and an oil passage hole two near the rear. The position of the first oil passage hole is such that it will only be exposed from the bottom of the piston when the piston rod is fully extended outward from the cylinder, connecting the internal space of the rodless chamber of the cylinder with the internal space of the second core tube. The P1 oil port at the bottom of the cylinder is connected to the internal space of the cylinder through the inner oil passage at the bottom of the cylinder; at the same time, the P1 oil port is connected to the oil passage at the tail of the core tube II through the inner oil passage at the bottom of the cylinder. The oil passage between the P1 oil port and the oil passage II is equipped with a one-way valve II that only allows liquid to flow from the inside of the core tube II through the oil passage II to the P1 oil port.

2. The sequential telescopic hydraulic cylinder according to claim 1, characterized in that: The oil passages of oil passage one, oil passage two, and oil passage three are isolated by a seal; the piston is equipped with a seal to isolate the oil passages between the rod chamber and the rodless chamber of the cylinder; the oil passage two at the tail of the core tube two is equipped with a seal to isolate it from the internal oil passages of the cylinder and the external space.

3. The sequential telescopic hydraulic cylinder according to claim 1, characterized in that: The T and P ports of the piston rod head are located in front of the rod head, while the A and B ports are located on top of the rod head.

4. The sequential telescopic hydraulic cylinder according to claim 1, characterized in that: A seal is provided between the outlet of oil passage one and the outlet of oil passage two on the outer wall of the piston; a seal is provided on the inner wall of the piston near the internal cavity of the piston rod to isolate the oil passage between oil passage one and the internal cavity of the piston rod; a seal is provided on the inner wall of the piston away from the internal cavity of the piston rod to isolate the oil passage between oil passage three and the internal cavity of the piston; a seal is provided at the end of the piston, which is a combined seal to isolate the oil passage between the rod chamber and the rodless chamber of the cylinder.

5. The sequential telescopic hydraulic cylinder according to claim 1, characterized in that: The oil passage hole at the tail of the core tube is provided with a seal five, which consists of a sealing ring at the front and rear of the oil passage hole two, thereby isolating the oil passage hole two from the internal oil passage of the cylinder and the external space.

6. The sequential telescopic hydraulic cylinder according to claim 1, characterized in that: The sequential telescopic cylinder is connected in series with a multi-stage cylinder, with the intermediate stage cylinder being the sequential telescopic cylinder and the last stage being a regular cylinder; the T1 and P1 ports on the cylinder barrel of the sequential telescopic cylinder are connected to a multi-way valve, and the T and P ports on the rod head are respectively connected to the T1' and P1' ports on the cylinder barrel of the next stage cylinder.

Images