Sequential telescopic oil cylinder and control valve thereof

Abstract

A piston rod head is provided with an oil port T, an oil port P, an oil port A and an oil port B, a stroke control valve and a spring self-resetting deflector rod valve element of the stroke control valve are installed, when the valve element pops up, the oil port A is in one-way communication with the oil port B, and when the valve element is compressed, the oil port A is in two-way communication with the oil port B; the B is connected with the oil port T; oil passing paths I, II and III are arranged at the bottom of the piston and are respectively communicated with the oil ports A, T and P; an oil port T1 and an oil port P1 are formed in the head and the bottom of the cylinder barrel respectively, T1 is communicated with the interior of the cylinder barrel through two rows of small holes of the cylinder barrel, and P1 is communicated with the interior of the cylinder barrel; the bottom of the cylinder barrel is provided with a second core pipe, the front end is open and communicated with the first core pipe, and the tail is communicated with P1 through a one-way valve. Sequential stretching and retracting are achieved, oil in a rod cavity only needs to enter and return through the stroke control valve when fully stretching to the tail end or fully stretching and retracting to the initial stage, a small hole of the cylinder barrel plays a role of a pilot oil way, the size of a loop structure is effectively reduced, the problems of high back pressure and large calorific value caused by unsmooth oil entering and returning are solved, and the hydraulic system is suitable for the folding arm crane industry.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic lifting equipment, in particular to a sequential telescopic oil cylinder and a control valve thereof. Background Art

[0002] In hydraulic lifting equipment, the oil circuits between 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 "Sequential Cylinder with Oil Inlet Control 201922294276.6" achieves the sequential extension of two series-connected cylinders by designing a first oil port that communicates with the rodless chamber of the cylinder, an oil pipe that communicates with the second flow channel, a first one-way valve between the oil pipe and the rodless chamber of the cylinder, and a second one-way valve between the third and fourth flow channels. Patent "Sequential Cylinder with Hydraulically Controlled One-Way Valve 202021813366.8" also features a hydraulically controlled one-way valve, with the first one-way valve oil port connected to the fourth oil port via the second one-way valve oil port. This structure prevents excessive back pressure on the return oil from the rod chamber. However, both of these solutions can only achieve sequential extension of the cylinders.

[0004] The patent "A Sequential Cylinder Anti-Disorder Sealing Structure 202123235722.X" provides a sealing structure to prevent disordered movement of sequential cylinders. It features a movable sleeve at the bottom of the cylinder, screwed to the cylinder bottom, a bidirectional V-shaped seal, a bidirectional V-shaped seal between the main and auxiliary pistons, a buffer plunger connected to the auxiliary piston's cylinder ball, and a core tube located within the oil guide tube, the other end of which pulls the spool in the combination valve. This solution can achieve sequential extension and retraction, but the cylinder must retract a short distance before stopping and achieving sequential retraction. The stroke control valve is located at the bottom of the cylinder, making it unsuitable for use in the folding arm crane industry.

[0005] Patents such as "Valve Core Sealing Structure, Valve, and Sequential Cylinder 202023211346.6" design a valve core sealing structure, including a valve core, push rod, and seals, to shut off the valve and enable sequential cylinder expansion and contraction. Patent "A Sequential Cylinder 201520861241.5" designs a multi-layer piston rod to achieve sequential expansion and contraction in series. However, in both of these solutions, the oil in the rod cavity of the cylinder must be returned through the control valve, which can easily lead to poor oil supply and return, resulting in high back pressure and heat generation.

[0006] Therefore, how to achieve completely coherent sequential extension and retraction of the series cylinders, how to ensure that the installation position of the stroke control valve is suitable for the folding arm crane industry, and how to avoid the occurrence of high back pressure and high heat generation caused by poor oil supply and return, 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 oil cylinder and its control valve. By adopting a specific stroke control valve structure, combined with the design of the internal component structure and oil circuit of the oil cylinder, the oil cylinder can be extended and retracted in a completely coherent sequence, and the installation position of the stroke control valve can be suitable for the folding arm crane industry, and it is not easy to have the phenomenon of high back pressure and high heat generation caused by poor oil supply and return, thereby solving the problems raised in the background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions: A sequential telescopic oil cylinder comprises a cylinder barrel and a piston rod, wherein a stroke control valve is installed at one end of the rod head of the piston rod and a piston is provided at the other end thereof and is installed in the cylinder barrel; The piston rod head is provided with four oil ports T, P, A, and B, and the B oil port is connected to the T oil port through the internal oil passage of the piston rod head; The stroke control valve is provided with two oil ports, A1 and B1, which are connected to the oil ports A and B respectively; a one-way valve is provided between the two oil ports A1 and B1; a spring self-reset lever valve core is provided on one side of the stroke control valve, which is normally in a pop-up state. When the spring self-reset lever valve core is popped out, oil flows from the oil port A to the oil port B in a one-way communication; when the spring self-reset lever valve core is compressed, the oil ports A and B are connected in two directions through the valve core; All piston rods are provided with a core tube 1 and a core tube 3, wherein the core tube 3 is outside and the core tube 1 is inside, and there is a gap between the core tube 3 and the core tube 1; There are three oil passages at the bottom of the piston, including oil passage 1, oil passage 2, and oil passage 3; The oil port A of the stroke control valve is connected to the oil passage 1 through the gap between the core tube 3 and the core tube 1; The B oil port of the stroke control valve is connected to the T oil port through the internal oil passage of the stroke control valve; the T oil port is connected to the second oil passage through the internal cavity of the piston rod and the internal oil passage of the piston; The oil port P of the stroke control valve is connected to the inner space of the core tube 1, and is connected to the oil passage 3 at the bottom of the piston through the core tube 1; The cylinder includes a cylinder head and a cylinder bottom, each of which is provided with an oil port T1 and an oil port P1; the oil port T1 of the cylinder head is connected to the internal space of the cylinder through two rows of small holes on the cylinder; A second core tube is installed at the bottom of the cylinder barrel. 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 the first core tube can be inserted into the first core tube during the movement of the piston rod. Two oil holes are opened on the wall of the second core tube, including the first oil hole at the front and the second oil hole near the rear. The position of the oil hole 1 is such that it will be exposed from the bottom of the piston only when the piston rod is fully extended out of the cylinder, connecting the internal space of the rodless cavity of the cylinder and the internal space of the core tube 2; The P1 oil port at the bottom of the cylinder is connected to the internal space of the cylinder through the oil channel at the bottom of the cylinder; at the same time, the P1 oil port is connected to the oil hole 2 at the tail of the core tube 2 through the oil channel at the bottom of the cylinder, and the oil channel between the P1 oil port and the oil hole 2 is installed with a one-way valve 2 that only allows liquid to flow from the inside of the core tube 2 through the oil hole 2 to the P1 oil port.

[0009] The oil circuits are isolated between the first oil passage, the second oil passage and the third oil passage by seals; the piston is provided with a seal to isolate the oil circuit between the rod chamber and the rodless chamber of the oil cylinder; the oil hole 2 at the tail of the second core tube is provided with a seal to isolate the oil circuit from the internal space of the cylinder.

[0010] The further specific designs are as follows: The T and P oil ports of the stroke control valve are located in front of the rod head, and the A and B oil ports are located above the rod head.

[0011] The core tube one and the core tube three are both connected to the rod head by welding.

[0012] A seal 1 is provided between the outlet of the oil passage 1 and the outlet of the oil passage 2 on the outer wall of the piston; a seal 2 is provided on the inner wall of the piston close to the internal cavity of the piston rod to isolate the oil path between the oil passage 1 and the internal cavity of the piston; a seal 3 is provided on the inner wall of the piston away from the internal cavity of the piston rod to isolate the oil path between the oil passage 3 and the internal cavity of the piston rod; a seal 4 is provided at the end of the piston, which is a combined seal to isolate the oil path between the rod cavity and the rodless cavity of the cylinder.

[0013] The oil through hole 2 at the tail of the core tube 2 is provided with a seal 5. The seal 5 is provided with a sealing ring in front and behind the oil through hole 2, so as to isolate the oil through hole 2 from the oil circuit in the internal space of the cylinder.

[0014] The T1 oil port on 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 pipeline and have 5 small holes each.

[0015] The core tube 2 is fixed at one end of the bottom of the cylinder and is installed through threads.

[0016] The stroke control valve includes a valve body, which has two oil ports A1 and B1 on the valve body. Two parallel oil circuits are set between the two oil ports A1 and B1 in the valve body. One oil circuit is provided with a one-way valve 1, so that the oil is not connected from B1 to the A1 oil port and is connected only from A1 to B1 oil port; the other oil circuit is provided with a spring self-returning lever valve core, which is normally in a pop-up state and is provided with a normally open valve core oil circuit. When the spring self-returning lever valve core is popped out, the valve core oil circuit does not play a role. When the spring self-returning lever valve core is compressed, two-way communication is achieved between the two oil ports A1 and B1 through the valve core oil circuit.

[0017] The working principle of the present invention is as follows: the sequential telescopic cylinder of the present invention is connected in series with a multi-stage cylinder, the intermediate-stage cylinder is a sequential telescopic cylinder of the same structure as the present invention, and the last stage is a common cylinder; the T1 and P1 oil ports on the cylinder barrel of the sequential telescopic cylinder are connected to the 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.

[0018] Sequential extension process: The oil pump supplies oil to the P1 oil port of the sequential telescopic cylinder through the multi-way valve. The oil enters the cylinder from the oil channel at the bottom of the cylinder barrel, pushing the cylinder forward. Before the oil hole 1 installed on the front wall of the core tube 2 at the bottom of the cylinder barrel is exposed from the bottom of the core tube piston, no oil enters the next-level cylinder and the lower-level cylinder is stationary. When the sequential telescopic cylinders are fully extended, the oil hole 1 is exposed from the bottom of the piston, and the oil enters the ordinary cylinder through the oil hole 1 to realize sequential extension. The sequential retraction process: the oil enters the internal cavity of the piston rod through the T1 oil port of the sequential telescopic cylinder and the oil through-hole 2 on the piston, and then enters the T1' oil port of the next-stage cylinder through the T oil port of the rod head, pushing the piston rod of the next-stage cylinder to retract. During this process, no oil enters the rod cavity of the sequential telescopic cylinder, so the sequential telescopic cylinder is stationary; when the next-stage cylinder is fully retracted, the mechanical collision block that follows the movement of the sequential telescopic cylinder hits the stroke control valve push rod of the rod head of the sequential telescopic cylinder to connect the B1 oil port to the A1 oil port, and then the rod head B oil port to the A oil port are connected. The oil enters the internal cavity of the piston rod through the oil through-hole 2 on the piston, and then enters the rod head B oil port to the A oil port, enters the core tube three through the internal oil channel of the rod head, and enters the rod cavity of the sequential telescopic cylinder through the oil through-hole 1 on the piston, pushing the sequential telescopic cylinder to retract.

[0019] During the extension process described above, during the initial extension phase, the oil in the rod chamber flows directly back to the oil tank through the two rows of small holes in the cylinder wall. Critical state: When the seal between oil passages 1 and 2 on the piston moves between the two rows of small holes in 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 2 on the piston. As the cylinder continues to extend, when the front row of small holes in the cylinder wall are located above the seal between oil passages 1 and 2, the oil in the rod chamber flows through core tube 3 into the stroke control valve of the rod head, and then through one-way valve 1 into the cavity in the piston rod, returning to the oil tank through oil passage 2 on the piston and the rear row of small holes in the cylinder wall. Therefore, in the critical state, the two rows of small holes in the cylinder wall provide an uninterrupted return circuit, allowing the cylinder to extend continuously and uninterruptedly.

[0020] During the extension process in the above sequence, the seal between the oil passages 1 and 2 on the piston can directly supply oil to the rod chamber through the front row of small holes below the oil port T1 of the cylinder, thereby increasing the oil flow efficiency and reducing the problem of excessive temperature rise caused by poor oil flow.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The stroke control valve of the present invention is installed on the piston rod head and is applicable to the folding arm crane industry; 2. The oil in the rod chamber of the oil cylinder involved in the patent of this invention needs to be fed back through the stroke control valve only in the initial stage and at the end of extension. After one of the two rows of small holes on the cylinder barrel runs to the left side of the seal between the oil passage 1 and the oil passage 2, the oil can be directly fed back; 3. The oil cylinder of the present invention can achieve strict sequential extension and retraction, and the oil needs to be inlet and return through the core tube and stroke control valve only when the oil cylinder is fully extended to the end or in the initial stage of full extension and retraction, which is equivalent to the pilot oil circuit, effectively reducing the structural size of the circuit and the problems of high back pressure and high heat generation caused by poor oil inlet and return. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural diagram of the oil cylinder and stroke control valve in the retracted state; Figure 2 for Figure 1 Schematic diagram of the structure along the MM section with the piston rod extended; Figure 3 for Figure 2 Enlarged view of the middle piston rod; Figure 4 for Figure 2 Enlarged view of the middle cylinder; Figure 5 for Figure 4 Schematic diagram of two rows of small holes in the F direction on the middle cylinder; Figure 6 This is the principle diagram of the stroke control valve; Figure 7 for Figure 3 An enlarged view of the piston rod head, where (b) is a cross-sectional view and (a) is the E-direction view of (b); Figure 8 for Figure 3 Enlarged view of the bottom of the middle piston rod; Figure 9 for Figure 4 Enlarged view of the middle cylinder head; Figure 10 for Figure 4 Enlarged view of the bottom of the middle cylinder; Figure 11 This is a schematic diagram of the structure of the sequential telescopic oil cylinder and the ordinary oil cylinder connected in series according to the present invention; Figure 12 for Figure 11 Schematic diagram of the middle piston running to position 1; Figure 13 for Figure 11 Schematic diagram of the middle piston moving to position 2.

[0023] In the figure: 1. Sequential telescopic cylinder; 2. Ordinary 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 1; 13. Core tube 2; 14. Core tube 3; 15. Oil hole 1; 16. Oil hole 2; 17. Oil passage 1; 18. Oil passage 2; 19. Oil passage 3; 20. Seal 1; 21. Seal 2; 22. Seal 3; 23. Seal 4; 24. Seal 5; 25. Valve body; 26. Spring self-reset lever valve core; 27. Valve core oil circuit; 28. One-way valve 1; 29. ​​One-way valve 2; 30. Multi-way valve. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Combine Figure 1-2 As shown, the present invention provides a sequential telescopic oil cylinder 1, comprising a cylinder 3 and a piston rod 4. A stroke control valve 5 is installed at one end of the rod head of the piston rod 4, and a piston 7 is installed at the other end of the rod head of the piston rod 4. Figure 1 As shown, the piston rod 4 is fully extended from the cylinder 3. Figure 2 shown.

[0026] Combine Figure 1、 2 As shown in Figures 3, 6, and 7, the rod head 6 of the piston rod has four oil ports, namely T, P, A, and B. The T and P oil ports are located in front of the rod head, while the A and B oil ports are located above the rod head. A stroke control valve 5 is installed on the rod head 6. The stroke control valve 5 has two oil ports, A1 and B1, which are connected to the A and B oil ports respectively.

[0027] Combine Figure 3 and Figure 8 As shown, the piston rod 4 is provided with core tube 1 12 and core tube 3 14, and the bottom of the piston is provided with three oil passages, including oil passage 1 17, oil passage 2 18, and oil passage 3 19. Core tube 1 12 and core tube 3 14 are both welded to the rod head 6, with core tube 3 14 on the outside and core tube 1 12 on the inside, with a gap between core tube 3 14 and core tube 1 12.

[0028] The A1 oil port of the stroke control valve 5 and the A oil port of the rod head 6 are connected to the oil passage 17 through the gap between the core tube 3 14 and the core tube 1 12; The B1 oil port of the stroke control valve 5 and the B oil port of the rod head 6 are connected to the T oil port through the internal oil passage of the rod head; the T oil port is connected to the oil diameter 18 through the internal cavity of the piston rod and the internal oil passage of the piston; The oil port P of the rod head 6 is connected to the inner space of the core tube 12, and is connected to the oil passage 3 19 at the bottom of the piston through the core tube 12; A seal 20 is provided between the outlet of the oil passage 17 and the outlet of the oil passage 2 18 on the outer wall of the piston 7; a seal 21 is provided on the inner wall of the piston 7 close to the internal cavity of the piston rod to achieve oil path isolation between the oil passage 17 and the internal cavity of the piston; a seal 3 22 is provided on the inner wall of the piston 7 away from the internal cavity of the piston rod to achieve oil path isolation between the oil passage 3 19 and the internal cavity of the piston rod; a seal 4 23 is provided at the end of the piston, which is a combined seal to achieve oil path isolation between the rod cavity and the rodless cavity of the cylinder.

[0029] Combine Figure 4 、 5 As shown in Figures 9 and 10, the cylinder 3 includes a cylinder head 8 and a cylinder bottom 9, each of which is provided with oil ports T1 and P1. The oil port T1 of the cylinder head 8 communicates with the interior of the cylinder through two rows of small holes in the cylinder, namely the front row of small holes 10 and the rear row of small holes 11.

[0030] The bottom 9 of the cylinder barrel is threadedly mounted with a core tube 13, which is an open front end and closed rear end structure. The diameter of core tube 13 is smaller than that of core tube 12, and the outer diameter of core tube 13 is matched with 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 stroke of the oil cylinder. Two oil holes are formed on the wall of core tube 13, including oil hole 15 at the front and oil hole 16 near the rear. The position of oil hole 15 is such that it will only be exposed from the bottom of the piston when the piston rod is fully extended from the cylinder barrel, connecting the internal space of the rodless cavity of the cylinder barrel with the internal space of core tube 13.

[0031] The oil through hole 2 16 at the tail of the core tube 2 13 is provided with a seal 5 24 . The seal 5 24 is provided with a sealing ring before and after the oil through hole 2 16 to isolate the oil through hole 2 16 from the internal oil circuit of the cylinder and the external space.

[0032] The P1 oil port at the bottom of the cylinder 9 is connected to the internal space of the cylinder through the oil channel at the bottom of the cylinder; at the same time, the P1 oil port is connected to the oil hole 2 16 at the tail of the core tube 2 13 through the oil channel at the bottom of the cylinder. The oil channel between the P1 oil port and the oil hole 2 16 is installed with a one-way valve 29 that only allows liquid to flow from the inside of the core tube 2 13 through the oil hole 2 16 to the P1 oil port.

[0033] like Figure 6 The figure shows the principle diagram of the stroke control valve, which includes a valve body 25. The valve body 25 has two oil ports A1 and B1 connected to the external oil circuit. Two parallel oil circuits are set between the two oil ports A1 and B1 in the valve body. One oil circuit is provided with a one-way valve 28 to prevent the oil from flowing from B1 to the A1 oil port and only connect the oil from A1 to the B1 oil port; the other oil circuit is provided with a spring self-returning lever valve core 26, which is normally in a pop-up state and is provided with a normally open valve core oil circuit 27. When the spring self-returning lever valve core 26 is popped out, the valve core oil circuit 27 does not function. When the spring self-returning lever valve core 26 is compressed, two-way communication is achieved between the two oil ports A1 and B1 through the valve core oil circuit 27.

[0034] The valve body 25 has two oil ports A1 and B1 connected to the external oil circuit. The oil circuits inside the two oil ports A1 and B1 are two parallel oil circuits: one oil circuit is provided with a one-way valve 28. The characteristics of this internal oil circuit are that the two oil ports B1 to A1 are not connected, and the two oil ports A1 to B are connected; the other oil circuit is provided with a spring self-reset lever valve core oil circuit. This valve core oil circuit is normally open. When the spring self-reset lever valve core is compressed, the two oil ports A1 and B1 are connected in both directions through the valve core. Figure 1 、 6, 7. Therefore, when the spring self-reset lever valve core 26 is in the pop-up state, the oil can only flow from A to B of the rod head; when the spring self-reset lever valve core 26 is impacted and in the compressed state, the two oil ports A and B of the rod head are completely connected, allowing the oil to flow freely between A and B.

[0035] The working principle of the present invention is as follows: Figure 11 As shown, the example uses the series connection of sequential telescopic cylinder 1 and conventional cylinder 2. The T1 and P1 ports on the barrel 3 of sequential telescopic cylinder 1 are connected to a multi-way valve 30, while the T and P ports on the rod head 6 are connected to the T1' and P1' ports on the barrel of conventional cylinder 2, respectively. A mechanical impact block is installed on the mechanical structure connected to conventional cylinder 2. When conventional cylinder 2 is fully retracted, the impact block strikes the spring-loaded self-resetting lever spool push rod of the rod head stroke control valve of sequential telescopic cylinder 1, fully connecting B1 to A1.

[0036] Sequential stretching: Oil inlet circuit: The oil pump supplies oil to the P1 oil port of the sequential telescopic oil cylinder 1 through the multi-way valve 30. The oil enters the cylinder from the oil circuit at the bottom of the cylinder to push the cylinder forward. The one-way valve between the P1 oil port and the core tube 2 13 prevents the oil from entering the core tube 2 13. Before the oil hole 15 installed on the front wall of the core tube 2 13 at the bottom of the cylinder is exposed from the bottom of the core tube piston, no oil enters the ordinary oil cylinder 2 and the ordinary oil cylinder 2 is stationary. Only when the sequential telescopic oil cylinder 1 is fully extended, the core tube 2 13 and the piston 7 reach the position shown in the figure. Figure 12 In the position shown, the oil hole 15 is exposed from the bottom of the piston 7, and the oil enters the internal space of the core tube 2 13 through the oil hole 15, and then enters the P1' oil port on the cylinder barrel of the ordinary cylinder 2 through the core tube 12 and the rod head P oil port, thereby extending the ordinary cylinder 2 and then achieving sequential extension.

[0037] Oil return circuit: When the cylinder is extended in the early stage, the oil in the rod cavity passes through the 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, and returns directly to the oil tank. Figure 13 As shown, when the seal between oil passages 17 and 18 on piston 7 moves between the two rows of small holes 10 and 11 in 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 18 on the piston. As the cylinder continues to extend, when the front row of small holes 10 in the cylinder wall lies above the seal between oil passages 17 and 18, the oil path is interrupted. The oil in the rod chamber then flows through oil passage 17 into core tube 3 14, reaching port A on the rod head, and then into stroke control valve 5 above the rod head. It then passes through check valve 1 28 into the piston rod cavity, and then returns to the oil tank through oil passage 18 on the piston and rear row of small holes 11 in the cylinder wall. Therefore, in a critical state, the two rows of small holes 10 and 11 in the cylinder wall provide an uninterrupted return circuit, enabling the cylinder to extend continuously and uninterrupted.

[0038] Sequential retraction: In this embodiment, two-stage oil cylinders are sequentially extended, simulating the situation where the sequential telescopic oil cylinder 1 has been fully extended and needs to be sequentially retracted.

[0039] Oil inlet circuit: Oil enters the piston rod cavity through port T1 of sequential telescopic cylinder 1, then enters port T of the rod head into port T1' of the downstream common cylinder 2, pushing the piston rod of common cylinder 2 back. This process is controlled by the rod head's stroke control valve 5, and the spring-loaded self-returning lever spool 26 is normally in the extended position. The flow from port B1 to port A1 is disconnected, preventing oil from entering the rod cavity of sequential telescopic cylinder 1, causing it to stop. Only when the ordinary oil cylinder 2 is fully retracted, the mechanical collision block following the movement of ordinary oil cylinder 2 hits the stroke control valve push rod of the rod head of the sequential telescopic oil cylinder 1, causing B1 to flow to A1. The oil enters the internal cavity of the piston rod through the oil passage 2 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 through B1 to A1, and then to the oil port A of the rod head, enters the gap between the core tube 3 14 and the core tube 1 12, and enters the rod cavity of the sequential telescopic oil cylinder 1 through the oil passage 1 17 on the piston, pushing the sequential telescopic oil cylinder 1 to retract. The seal between the oil passage 1 17 and the oil passage 2 18 on the piston can directly supply oil to the rod cavity through the front row of small holes 10 below the oil port of the cylinder barrel T1, increasing oil flow efficiency and reducing the problem of excessive temperature rise caused by poor oil flow.

[0040] Oil return circuit: The oil in the rodless chamber of the ordinary oil cylinder 2 is connected to the P oil port of the rod head of the sequential telescopic oil cylinder 1 through the P1' oil port, enters the internal space of the core tube 12 in the piston rod of the sequential telescopic oil cylinder 1, connects to the core tube 2 13 in the cylinder barrel, and then connects to the P1 oil port through the one-way valve 28 at the bottom of the cylinder barrel of the sequential telescopic oil cylinder 1, and returns to the oil tank.

[0041] The stroke control valve of the present invention is installed at the piston rod head. Compared with the solution in which the stroke control valve is installed at the bottom of the cylinder, the stroke control valve of the present invention is applicable to the folding arm crane industry.

[0042] The hydraulic cylinder of the present invention achieves strict sequential extension and retraction. Two rows of small holes are designed in the barrel of the sequential telescopic cylinder to provide oil flow during critical conditions, acting as a pilot oil circuit. Oil in the rod chamber of this section only enters and returns through core tube 3 14 and the stroke control valve during full extension or the initial stages of retraction. Oil can be directly returned through the front row of small holes 10 in the two rows of small holes in the barrel F after reaching the left side of seal 1 20. This design effectively reduces the structural size of the circuit and mitigates the problems of high back pressure and heat generation caused by poor oil supply and return.

[0043] Other embodiments: The present invention realizes the sequential extension and retraction of multi-stage oil cylinders. It only requires that the multi-stage oil cylinders are connected in series according to the method provided by the present invention. The first stages are the sequential extension and retraction oil cylinders provided by the present invention, and the last stage is an ordinary oil cylinder. The oil ports T1 and P1 of the first stage sequential extension and retraction oil cylinder are connected to the multi-way valve, and the upper stage T and P oil ports are connected to the lower stage T and P oil ports, so that the multi-stage oil cylinders can be sequentially extended and retracted.

[0044] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A sequential telescopic oil cylinder, comprising a cylinder barrel and a piston rod, characterized in that: A stroke control valve is installed at one end of the rod head of the piston rod, and a piston is installed at the other end, which is installed in the cylinder; The piston rod head is provided with four oil ports T, P, A, and B, and the B oil port is connected to the T oil port through the internal oil passage of the piston rod head; The stroke control valve is provided with two oil ports, A1 and B1, which are connected to the oil ports A and B respectively; a one-way valve is provided between the two oil ports A1 and B1; a spring self-reset lever valve core is provided on one side of the stroke control valve, which is normally in a pop-up state. When the spring self-reset lever valve core is popped out, oil flows from the A1 oil port to the B1 oil port in a one-way communication; when the spring self-reset lever valve core is compressed, the A1 and B1 oil ports are in two-way communication through the valve core; The bottom of the piston is provided with oil passage 1, oil passage 2 and oil passage 3; the oil port A of the piston rod head is connected to the oil passage 1, the oil port T is connected to the oil passage 2, and the oil port P is connected to the oil passage 3 at the bottom of the piston; The cylinder includes a cylinder head and a cylinder bottom, each of which is provided with an oil port T1 and an oil port P1; the oil port T1 of the cylinder head is connected to the internal space of the cylinder through two rows of small holes on the cylinder; A second core tube is installed at the bottom of the cylinder barrel. The second core tube is open at the front end and closed at the rear end. The diameter of the second core tube is smaller than that of the first core tube and the first core tube can be inserted into the first core tube during the movement of the piston rod. Two oil holes are opened on the wall of the second core tube, including the first oil hole at the front and the second oil hole near the rear end. The position of the first oil hole is such that it will be exposed from the bottom of the piston only when the piston rod is fully extended out of the cylinder barrel, thereby connecting the internal space of the rodless cavity of the cylinder barrel 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 oil channel at the bottom of the cylinder; at the same time, the P1 oil port is connected to the oil hole 2 at the tail of the core tube 2 through the oil channel at the bottom of the cylinder, and the oil channel between the P1 oil port and the oil hole 2 is installed with a one-way valve 2 that only allows liquid to flow from the inside of the core tube 2 through the oil hole 2 to the P1 oil port.

2. The sequential telescopic cylinder according to claim 1, characterized in that: The piston rod is provided with a core tube 1 and a core tube 3, wherein the core tube 3 is outside and the core tube 1 is inside, and there is a gap between the core tube 3 and the core tube 1; The oil port A of the stroke control valve is connected to the oil passage 1 through the gap between the core tube 3 and the core tube 1; The T oil port is connected to the second oil passage through the internal cavity of the piston rod and the internal oil passage of the piston; The P oil port of the piston rod head is connected to the internal space of the core tube 1, and is connected to the oil passage 3 at the bottom of the piston through the core tube 1.

3. The sequential telescopic cylinder according to claim 2, characterized in that: The oil circuits are isolated between the first, second and third oil passages by seals; the piston is provided with a seal to isolate the oil circuit between the rod chamber and the rodless chamber of the oil cylinder; the second oil hole at the tail of the second core tube is provided with a seal to isolate it from the oil circuit inside the cylinder and the external space.

4. The sequential telescopic cylinder according to claim 1, characterized in that: The T and P oil ports of the piston rod head are located in front of the rod head, and the A and B oil ports are located above the rod head.

5. The sequential telescopic cylinder according to claim 2, characterized in that: A seal 1 is provided between the outlet of the oil passage 1 and the outlet of the oil passage 2 on the outer wall of the piston; a seal 2 is provided on the inner wall of the piston close to the internal cavity of the piston rod to isolate the oil path between the oil passage 1 and the internal cavity of the piston; a seal 3 is provided on the inner wall of the piston away from the internal cavity of the piston rod to isolate the oil path between the oil passage 3 and the internal cavity of the piston rod; a seal 4 is provided at the end of the piston, which is a combined seal to isolate the oil path between the rod cavity and the rodless cavity of the cylinder.

6. The sequential telescopic cylinder according to claim 2, characterized in that: The oil through hole 2 at the tail of the core tube 2 is provided with a seal 5. The seal 5 is a sealing ring provided in front and behind the oil through hole 2, so as to isolate the oil through hole 2 from the internal oil circuit of the cylinder and the external space.

7. The sequential telescopic cylinder according to claim 1, characterized in that: The T1 oil port on 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 pipeline and have 5 small holes each.

8. The sequential telescopic cylinder according to claim 1, characterized in that: The stroke control valve includes a valve body, which has two oil ports A1 and B1 on the valve body. Two parallel oil circuits are set between the two oil ports A1 and B1 in the valve body. One oil circuit is provided with a one-way valve 1, so that the oil is not connected from B1 to the A1 oil port and is connected only from A1 to B1 oil port; the other oil circuit is provided with a spring self-returning lever valve core, which is normally in a pop-up state and is provided with a normally open valve core oil circuit. When the spring self-returning lever valve core is popped out, the valve core oil circuit does not play a role. When the spring self-returning lever valve core is compressed, two-way communication is achieved between the two oil ports A1 and B1 through the valve core.

9. The sequential telescopic cylinder according to claim 1, characterized in that: The sequential telescopic cylinder is connected in series with the multi-stage cylinder, the middle-stage cylinder is the sequential telescopic cylinder, and the last stage is a common cylinder; the T1 and P1 oil ports on the cylinder barrel of the sequential telescopic cylinder are connected to the 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.

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