Double-oil-cylinder hydraulic synchronous control system and aerial work equipment

Abstract

The utility model discloses a double oil cylinder hydraulic synchronous control system and aerial work equipment, including the inner and outer side telescopic oil cylinder of series connection and with main control valve connection, be equipped with outer cylinder balance valve between main control valve and the rodless chamber of outer side telescopic oil cylinder, the rod chamber of inner side telescopic oil cylinder is connected with main control valve in proper order and is equipped with inner cylinder balance valve, intermediate balance valve and outer cylinder balance valve, the rod chamber of outer side telescopic oil cylinder is connected with the rodless chamber of inner side telescopic oil cylinder in proper order and is equipped with intermediate balance valve and inner cylinder balance valve, intermediate balance valve includes first oil channel and second oil channel each other parallelly connected, and first pilot valve and first check valve are provided with parallelly connected on second oil channel, and the pilot power port of first pilot valve is communicated with first oil channel, and first check valve is one -way guide to the one end of inner cylinder balance valve. Advantageous effects: the utility model can avoid the arm frame to move because of inertia, increase security, make the rod chamber and the rodless chamber of oil cylinder communicate, and the oil liquid with air bubble directly flows back oil tank and exhausts, is convenient and safe.

Description

Technical Field

[0001] This utility model relates to a hydraulic system, and more particularly to a dual-cylinder hydraulic synchronous control system and an aerial work platform, belonging to the field of engineering vehicle technology. Background Technology

[0002] Telescopic boom forklifts are special engineering vehicles designed for efficient material handling. Equipped with telescopic forks and various attachments, they can flexibly adapt to the loading and unloading needs of goods of different sizes. Combining the advantages of forklifts and loaders, they are suitable for heavy-duty operations in confined spaces. They possess excellent performance characteristics such as safety, efficiency, and adaptability to different working conditions.

[0003] The telescopic boom is relatively long. Telescopic boom forklifts using three-section booms employ a combination of chain and telescopic cylinder for telescopic movement. However, chain drive has the following problems: 1. Telescopic boom forklifts perform loading and unloading operations similar to loaders, and the chain drive is prone to loosening, resulting in poor synchronization of the telescopic boom's movement, requiring regular adjustment of tension; 2. Since the three-section boom is driven by a chain, if the chain breaks, the three-section boom will lose control, posing a risk.

[0004] In addition to chain-driven three-section arms, there is a dual-cylinder solution that uses components such as flow divider valves and displacement sensors. However, the above solutions increase costs due to the use of additional components and occupy too much space.

[0005] Chinese patent CN 220886918 U discloses a dual-cylinder hydraulic system and aerial work platform. However, its proposed dual-cylinder synchronization scheme fails to address the problem of air entering the system after prolonged operation or parking, causing the dual cylinders to lose synchronization. Furthermore, telescopic boom forklifts typically employ main control valves with significant leakage to improve efficiency, leading to more air entering the hydraulic system and further affecting the synchronization of the dual cylinders. Additionally, when the vehicle is loaded with heavy loads and the brakes are applied, the boom is prone to lurching out due to inertia, posing a safety hazard. Summary of the Invention

[0006] Purpose of the Invention: The purpose of this invention is to address the synchronization and lateral movement problems in existing dual-telescopic cylinder systems by providing a dual-cylinder hydraulic synchronization control system and aerial work platform. By integrating a mechanically controlled one-way valve at the bottom of the cylinder, when the cylinder is fully retracted, the one-way valve on the piston rod contacts the cylinder bottom, opening the valve and connecting the large and small chambers of the cylinder. Through continuous pressure buildup, air is expelled to the oil tank, thus solving the cylinder synchronization problem. Simultaneously, a balance valve is added between the two telescopic cylinders to effectively prevent lateral movement due to boom inertia.

[0007] Technical Solution: A dual-cylinder hydraulic synchronous control system includes an outer telescopic cylinder and an inner telescopic cylinder. The rod-side chamber of the outer telescopic cylinder is connected to the rodless chamber of the inner telescopic cylinder. The rodless chamber of the outer telescopic cylinder and the rod-side chamber of the inner telescopic cylinder are respectively connected to a main control valve. The annular cross-sectional area of ​​the rod-side chamber of the outer telescopic cylinder is the same as the cross-sectional area of ​​the rodless chamber of the inner telescopic cylinder. An outer cylinder balance valve is provided between the main control valve and the rodless chamber of the outer telescopic cylinder. The rod-side chamber of the inner telescopic cylinder is connected to the main control valve via an inner cylinder balance valve, an intermediate balance valve, and an outer cylinder balance valve. The rod-side chamber of the outer telescopic cylinder is connected to the rodless chamber of the inner telescopic cylinder via an intermediate balance valve and an inner cylinder balance valve. The intermediate balance valve includes a first oil passage and a second oil passage connected in parallel. The first oil passage is connected at both ends to the inner cylinder balance valve and the rod chamber of the outer telescopic cylinder, respectively. The first oil passage is connected to the rodless chamber of the inner telescopic cylinder through the inner cylinder balance valve. The second oil passage is connected at both ends to the outer cylinder balance valve and the inner cylinder balance valve, respectively. The second oil passage is connected to the rod chamber of the inner telescopic cylinder through the inner cylinder balance valve. A first pilot valve and a first check valve are connected in parallel on the second oil passage. The pilot power take-off port of the first pilot valve is connected to the first oil passage. The first check valve is unidirectionally directed to one end of the inner cylinder balance valve.

[0008] Telescopic boom forklifts often operate at high speeds with the boom fully retracted and carrying a heavy load. When the driver applies the brakes, the load on the forks will cause the three-section boom to move outward due to inertia. The inner telescopic cylinder is connected to the three-section boom and the two-section boom. In this state, the inner telescopic cylinder tends to extend outward, and the volume of the rodless chamber of the cylinder increases. As a result, the pilot pressure from V1 to C1 at the intermediate balance valve decreases, causing the valve core of the intermediate balance valve to close. The oil in the rod chamber of the inner telescopic cylinder tends to flow outward. At this time, the oil is locked at port C2 of the intermediate balance valve, thus preventing the boom from moving due to inertia.

[0009] In a preferred embodiment, to improve system safety, the first pilot valve is provided with two parallel pilot power take-off ports, namely the first oil passage and the second oil passage near the end of the inner cylinder balance valve. The pilot ratio of the pilot power take-off port connected to the first oil passage is a labor-saving pilot ratio, and the pilot ratio of the pilot power take-off port connected to the end of the second oil passage near the end of the inner cylinder balance valve is a labor-intensive pilot ratio.

[0010] The labor-saving pilot ratio is 1:2, 1:3, or 1:4, meaning a relatively small pressure in the first oil passage is sufficient to open the first pilot valve; conversely, a pilot pressure of 1:1 or 2:1 is required for the first pilot valve to open. When the boom impacts a wall or other object, the system is locked, and the pressure will rise indefinitely until components are damaged. For system safety, a pilot pressure value is set for the second oil passage. When the pressure is reached, the system will open to release pressure, providing a safety protection function.

[0011] In a preferred embodiment, to achieve locking of the telescopic hydraulic circuit, the main control valve is a three-position four-way valve. When no control signal is input, it is in the neutral position, locking the oil inlet and outlet circuits of the dual-cylinder hydraulic system. The other two positions of the main control valve switch the inlet and outlet ports to control the simultaneous extension or retraction of the dual cylinders. During cargo transportation, the telescopic boom forklift needs to keep the boom relatively stationary. After completing the extension / retraction action, the control signal is cut off, and the main control valve of the three-position four-way valve returns to the neutral position. In the neutral position, the four ports are not interconnected, locking the oil in the telescopic cylinders within the oil circuit, thus achieving locking of the telescopic boom.

[0012] In a preferred embodiment, to improve the opening response speed of the inner cylinder balance valve, the inner cylinder balance valve includes a second pilot valve and a direct-connect oil circuit. The second pilot valve connects the rod chamber of the outer telescopic cylinder to the rodless chamber of the inner telescopic cylinder. The direct-connect oil circuit connects the rod chamber of the inner telescopic cylinder to the first pilot valve of the intermediate balance valve. The pilot oil circuit of the second pilot valve is equipped with a relief valve, an adjustable flow valve, and a second check valve connected in parallel. In winter, when the oil is viscous or under high pressure, the adjustable flow valve has a small damping orifice and insufficient oil flow capacity. The relief valve can quickly fill the pilot oil, improving the opening response speed of the balance valve. The second check valve is used to quickly establish pilot pressure.

[0013] In a preferred embodiment, to facilitate the removal of air from the hydraulic system, the outer telescopic cylinder and the inner telescopic cylinder are respectively provided with mechanically triggered check valves that connect the rod chamber and the rodless chamber. The triggering mechanism of the mechanically triggered check valve is located at the bottom of the cylinder piston and is triggered by contact with the bottom of the inner side of the cylinder body.

[0014] After a period of use, air inevitably enters the hydraulic system, affecting the synchronization of cylinder extension and retraction. Asynchronous cylinder movement can eventually break the hydraulic pipes connecting the cylinders. To prevent this, mechanically triggered check valves are integrated on the piston rods of both the outer and inner extension cylinders. When the hydraulic system needs venting, with the boom fully retracted, continuing the retraction action causes the piston rod to press against the cylinder, opening the mechanically triggered check valves. This allows hydraulic fluid to flow from port A1 of the main control valve to the rod chamber of the inner extension cylinder, then from the mechanically triggered check valve on the piston to the rodless chamber of the inner extension cylinder, and finally from the rodless chamber to the rod chamber of the outer extension cylinder. Similarly, after triggering the mechanically triggered check valve, hydraulic fluid flows from the rod chamber to the rodless chamber of the outer extension cylinder, and then back into the oil tank via port B1 of the main control valve, forming a passage for venting. Exhaust can be completed without removing any pipes or valves, making exhaust maintenance simpler and more convenient, and improving the reliability of dual-cylinder synchronization.

[0015] A high-altitude work equipment includes the aforementioned dual-cylinder hydraulic synchronous control system. The dual-cylinder hydraulic synchronous control system is used to drive the rod chamber of the outer telescopic cylinder to move synchronously with the inner telescopic cylinder, while cutting off the oil circuit of the rod chamber of the inner telescopic cylinder when the system is locked.

[0016] The outer telescopic cylinder and the inner telescopic cylinder are respectively equipped with mechanically triggered one-way valves that connect the rod chamber and the rodless chamber. The triggering mechanism of the mechanically triggered one-way valve is located at the bottom of the cylinder piston and is triggered by contact with the bottom of the inner side of the cylinder body.

[0017] The aerial work equipment is a telescopic boom forklift.

[0018] The telescopic boom consists of a first-stage boom, a second-stage boom, and a third-stage boom nested in sequence. The outer telescopic cylinder is installed outside the first-stage boom to drive the second-stage boom to telescopically extend relative to the first-stage boom; the inner telescopic cylinder is fitted inside the second-stage boom to drive the third-stage boom to telescopically extend relative to the second-stage boom.

[0019] Beneficial effects: This utility model solves the problem that air inevitably enters the hydraulic system after long-term operation and parking. Conventional hydraulic cylinders cannot directly circulate the oil with the system, making it difficult to remove air. Removing the cylinder balance valve to vent air poses risks, and the sprayed hydraulic oil can easily cause pollution. This utility model connects the rod chamber and rodless chamber of the cylinder, allowing the oil containing air bubbles to flow directly back to the oil tank for venting, which is convenient and safe.

[0020] Telescopic boom forklifts can travel at speeds up to 40 km / h. When braking while the boom is loaded with a heavy load, the boom is prone to slipping out, affecting the synchronization of subsequent actions. Furthermore, the slipping of the boom can also easily cause collisions and other risks. This invention ensures that the boom only extends when an action command is given, thus increasing safety. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a hydraulic schematic diagram of the present invention. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0025] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0026] like Figure 1 As shown, a dual-cylinder hydraulic synchronous control system for a telescopic boom forklift includes an outer telescopic cylinder 1 and an inner telescopic cylinder 2. The rod-side chamber of the outer telescopic cylinder 1 is connected to the rodless chamber of the inner telescopic cylinder 2. The rodless chamber of the outer telescopic cylinder 1 and the rod-side chamber of the inner telescopic cylinder 2 are respectively connected to a main control valve 3. The annular cross-sectional area of ​​the rod-side chamber of the outer telescopic cylinder 1 is the same as the cross-sectional area of ​​the rodless chamber of the inner telescopic cylinder 2. An outer cylinder balance valve 4 is provided between the main control valve 3 and the rodless chamber of the outer telescopic cylinder 1. The rod-side chamber of the inner telescopic cylinder 2 is connected to the main control valve 3 via an inner cylinder balance valve 5, an intermediate balance valve 6, and an outer cylinder balance valve 4. The rod-side chamber of the outer telescopic cylinder 1 is connected to the rodless chamber of the inner telescopic cylinder 2 via an intermediate balance valve 6 and an inner cylinder balance valve 5. The intermediate balance valve 6 includes a first oil passage 61 and a second oil passage 62 connected in parallel. The two ends of the first oil passage 61 are respectively connected to the inner cylinder balance valve 5 and the rod chamber of the outer telescopic cylinder 1. The first oil passage 61 is connected to the rodless chamber of the inner telescopic cylinder 2 through the inner cylinder balance valve 5. The two ends of the second oil passage 62 are respectively connected to the outer cylinder balance valve 4 and the inner cylinder balance valve 5. The second oil passage 62 is connected to the rod chamber of the inner telescopic cylinder 2 through the inner cylinder balance valve 5. A first pilot valve 63 and a first check valve 64 are connected in parallel on the second oil passage 62. The pilot power take-off port of the first pilot valve 63 is connected to the first oil passage 61, and the first check valve 64 is unidirectionally directed to one end of the inner cylinder balance valve 5.

[0027] Telescopic boom forklifts often operate at high speeds with the boom fully retracted and carrying a heavy load. When the driver applies the brakes, the load on the forks will cause the three-section boom to move outward due to inertia. The inner telescopic cylinder 2 is connected to the three-section boom and the two-section boom. In this state, the inner telescopic cylinder 2 tends to extend outward, and the volume of the rodless chamber of the cylinder increases. Consequently, the pilot pressure from V1 to C1 at the intermediate balance valve 6 decreases, causing the valve core of the intermediate balance valve 6 to close. The oil in the rod chamber of the inner telescopic cylinder 2 tends to flow outward. At this time, the oil is locked at port C2 of the intermediate balance valve 6, thus preventing the boom from moving due to inertia.

[0028] To improve system safety, the first pilot valve 63 is provided with two parallel pilot power take-off ports, namely the first oil passage 61 and the second oil passage 62, which are located near the inner cylinder balance valve 5. The pilot ratio of the pilot power take-off port connected to the first oil passage 61 is a labor-saving pilot ratio, and the pilot ratio of the pilot power take-off port connected to the second oil passage 62 near the inner cylinder balance valve 5 is a labor-intensive pilot ratio.

[0029] The labor-saving pilot ratio is 1:2, 1:3, or 1:4. A relatively small pressure in the first oil passage 61 is sufficient to open the first pilot valve 63; conversely, a pilot pressure of 1:1 or 2:1 is required for the first pilot valve 63 to open. When the boom impacts a wall or other object, the system is locked, and the pressure will rise indefinitely until components are damaged. For system safety, a pilot pressure value is set for the second oil passage 62. When the pressure is reached, it will open to release pressure, providing a safety protection function.

[0030] To lock the telescopic boom's hydraulic circuit, the main control valve 3 is a three-position four-way valve. When there is no control signal input, it is in the neutral position, locking the inlet and outlet oil circuits of the dual-cylinder hydraulic system. The other two positions of the main control valve 3 switch the inlet and outlet ports to control the simultaneous extension or retraction of the dual cylinders. During cargo transportation, the telescopic boom of the forklift needs to remain relatively stationary. After completing the extension and retraction action, the control signal is cut off, and the main control valve 3 of the three-position four-way valve returns to the neutral position. In the neutral position, the four oil ports are not interconnected, and the oil in the telescopic cylinder is locked in the oil circuit, thereby locking the telescopic boom.

[0031] To improve the opening response speed of the inner cylinder balance valve 5, the inner cylinder balance valve 5 includes a second pilot valve 51 and a straight-through oil passage 52. The second pilot valve 51 connects the rod chamber of the outer telescopic cylinder 1 and the rodless chamber of the inner telescopic cylinder 2. The straight-through oil passage 52 connects the rod chamber of the inner telescopic cylinder 2 and the first pilot valve 63 of the intermediate balance valve 6. The pilot oil passage of the second pilot valve 51 is provided with an overflow valve 53, an adjustable flow valve 54 and a second check valve 55 connected in parallel.

[0032] In winter, when the oil is viscous or under high pressure, the damping opening of the adjustable flow valve 54 is small and the oil flow capacity is insufficient. The overflow valve 53 can quickly fill the pilot oil to improve the response speed of the balance valve opening. The second check valve 55 is used to quickly establish the pilot pressure.

[0033] To facilitate the removal of air from the hydraulic system, the outer telescopic cylinder 1 and the inner telescopic cylinder 2 are respectively equipped with mechanically triggered check valves 7 that connect the rod chamber and the rodless chamber. The triggering mechanism of the mechanically triggered check valve 7 is located at the bottom of the cylinder piston and is triggered by contact with the bottom of the inner side of the cylinder body.

[0034] After a period of use, air inevitably enters the hydraulic system, affecting the synchronization of cylinder extension and retraction. Asynchronous cylinder movement can eventually break the hydraulic pipes connecting the cylinders. To prevent this, mechanically triggered check valves 7 are integrated on the piston rods of the outer extension cylinder 1 and the inner extension cylinder 2. When the hydraulic system needs venting, with the boom fully retracted, continuing the retraction action causes the piston rod to press against the cylinder, opening the mechanically triggered check valve 7. This allows hydraulic fluid to flow from port A1 of the main control valve 3 to the rod chamber of the inner extension cylinder 2, then from the mechanically triggered check valve 7 to the rodless chamber of the inner extension cylinder 2, and finally from the rodless chamber to the rod chamber of the outer extension cylinder 1. Similarly, after triggering the mechanically triggered check valve 7, hydraulic fluid in the outer extension cylinder 1 flows from the rod chamber to the rodless chamber, and then back into the oil tank through port B1 of the main control valve 3, forming a passage for venting. Exhaust can be completed without removing any pipes or valves, making exhaust maintenance simpler and more convenient, and improving the reliability of dual-cylinder synchronization.

[0035] Working principle: When the main control valve 3 is in the neutral position without signal input, it locks the telescopic oil circuit. When the coil is energized, the valve core reverses, and oil flows out from port B1, corresponding to a synchronous extension action; oil flows out from port A1, corresponding to a synchronous retraction action.

[0036] Synchronous extension action: High-pressure oil is output from port B1 of the main control valve 3 to the outer telescopic cylinder 1. After passing through port V2 to port C2 via the check valve, the oil reaches the rodless chamber of the outer telescopic cylinder 1. The pressurized oil pushes the outer telescopic cylinder 1 out, forcing the oil in the rod chamber out through the intermediate balance valve 6. The oil then passes through port V1 to port C1 of the intermediate balance valve 6 to port V2 of the inner cylinder balance valve 5, passes through the check valve to port C2, and finally reaches the rodless chamber of the inner telescopic cylinder 2. The annular area of ​​the rod chamber of the outer telescopic cylinder 1 is the same as the piston rod area of ​​the rodless chamber of the inner telescopic cylinder 2, thus ensuring that the extension and retraction strokes of the inner and outer cylinders are identical. When the inner telescopic cylinder 2 extends, it squeezes out the oil in the rod chamber, which passes through ports C1 to V1 of the inner cylinder balance valve 5 and reaches port C2 of the intermediate balance valve 6. Due to the pressure acting on ports V1 to C1 of the intermediate balance valve 6 during extension, the pilot pressure opens the valve core of the intermediate balance valve 6. Thus, the oil coming out of the rod chamber of the inner telescopic cylinder 2 can pass through ports C2 to V2 of the intermediate balance valve 6 and return to port A1 of the main control valve 3 to the oil tank, completing the entire extension action.

[0037] Synchronous retraction action: High-pressure oil output from port A1 of the main control valve passes through the check valve of the outer telescopic cylinder 1, the check valve of the intermediate balance valve 6, and the inner cylinder balance valve 5, finally reaching the rod chamber of the inner telescopic cylinder 2. During the retraction process, the oil in the rodless chamber of the inner telescopic cylinder 2 is squeezed out to port C2 of the inner cylinder balance valve 5. The inner cylinder balance valve 5 integrates an adjustable flow valve 54 and an overflow valve 53. By adjusting the size of the damping orifice and the overflow valve 53, the opening characteristics and response speed of the valve core during cylinder retraction can be optimized. During retraction, the pilot pressure at ports C1 to V1 of the inner cylinder balance valve 5 opens the valve core, and the oil in the rodless chamber of the inner telescopic cylinder 2 flows through ports C2 to V2 of the inner cylinder balance valve 5, and then flows to the rod chamber of the outer telescopic cylinder 1, squeezing the oil in the rodless chamber of the outer telescopic cylinder 1 to the outer telescopic balance valve C2, and then flowing back to the oil tank through port B1 of the main control valve 3, completing the entire retraction action.

[0038] Anti-slip locking: Telescopic boom forklifts often operate at high speeds with the boom fully retracted and carrying heavy loads. When the driver applies the brakes, the load on the forks will cause the three-section boom to move outward due to inertia. The inner telescopic cylinder 2 is connected to the three-section boom and the two-section boom. In this state, the inner telescopic cylinder 2 tends to extend outward, and the volume of the rodless chamber of the cylinder increases. As a result, the pilot pressure from V1 to C1 at the intermediate balance valve 6 decreases, the valve core of the intermediate balance valve 6 closes, and the oil in the rod chamber of the inner telescopic cylinder 2 tends to flow outward. At this time, the oil is locked at port C2 of the intermediate balance valve 6, thus preventing the boom from slipping due to inertia.

[0039] A high-altitude work equipment includes the aforementioned dual-cylinder hydraulic synchronous control system. The dual-cylinder hydraulic synchronous control system is used to drive the rod chamber of the outer telescopic cylinder 1 to move synchronously with the inner telescopic cylinder 2, while cutting off the oil circuit of the rod chamber of the inner telescopic cylinder 2 when the system is locked.

[0040] The outer telescopic cylinder 1 and the inner telescopic cylinder 2 are respectively equipped with mechanically triggered one-way valves 7 that connect the rod chamber and the rodless chamber. The triggering mechanism of the mechanically triggered one-way valve 7 is located at the bottom of the cylinder piston and is triggered by contact with the bottom of the inner side of the cylinder body.

[0041] The aerial work equipment is a telescopic boom forklift.

[0042] The telescopic boom consists of a first-stage boom, a second-stage boom, and a third-stage boom nested in sequence. The outer telescopic cylinder 1 is installed outside the first-stage boom to drive the second-stage boom to telescopically extend relative to the first-stage boom; the inner telescopic cylinder 2 is fitted inside the second-stage boom to drive the third-stage boom to telescopically extend relative to the second-stage boom.

[0043] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0044] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dual-cylinder hydraulic synchronous control system, comprising an outer telescopic cylinder (1) and an inner telescopic cylinder (2), wherein the rod chamber of the outer telescopic cylinder (1) is connected to the rodless chamber of the inner telescopic cylinder (2); the rodless chamber of the outer telescopic cylinder (1) and the rod chamber of the inner telescopic cylinder (2) are respectively connected to a main control valve (3), and the annular cross-sectional area of ​​the rod chamber of the outer telescopic cylinder (1) is the same as the cross-sectional area of ​​the rodless chamber of the inner telescopic cylinder (2); characterized in that: An outer cylinder balance valve (4) is provided between the main control valve (3) and the rodless chamber of the outer telescopic cylinder (1); the rod chamber of the inner telescopic cylinder (2) is connected to the main control valve (3) through an inner cylinder balance valve (5), an intermediate balance valve (6) and an outer cylinder balance valve (4); the rod chamber of the outer telescopic cylinder (1) is connected to the rodless chamber of the inner telescopic cylinder (2) through an intermediate balance valve (6) and an inner cylinder balance valve (5). The intermediate balance valve (6) includes a first oil passage (61) and a second oil passage (62) connected in parallel. The two ends of the first oil passage (61) are respectively connected to the inner cylinder balance valve (5) and the rod chamber of the outer telescopic cylinder (1); the two ends of the second oil passage (62) are respectively connected to the outer cylinder balance valve (4) and the inner cylinder balance valve (5); a first pilot valve (63) and a first check valve (64) are connected in parallel on the second oil passage (62). The pilot power take-off port of the first pilot valve (63) is connected to the first oil passage (61), and the first check valve (64) is unidirectionally connected to the inner cylinder balance valve (5).

2. The dual-cylinder hydraulic synchronous control system according to claim 1, characterized in that: The first pilot valve (63) has two parallel pilot power take-off ports, namely the first oil passage (61) and the second oil passage (62) near the end of the inner cylinder balance valve (5). The pilot ratio of the pilot power take-off port connected to the first oil passage (61) is a labor-saving pilot ratio, and the pilot ratio of the pilot power take-off port connected to the second oil passage (62) near the end of the inner cylinder balance valve (5) is a labor-intensive pilot ratio.

3. The dual-cylinder hydraulic synchronous control system according to claim 1, characterized in that: The main control valve (3) is a three-position four-way valve. When there is no control signal input, it is in the middle position to lock the oil inlet and outlet oil circuits of the dual-cylinder hydraulic system. The other two positions of the main control valve (3) switch the inlet and outlet oil ports to control the dual cylinders to extend or retract simultaneously.

4. The dual-cylinder hydraulic synchronous control system according to claim 1, characterized in that: The inner cylinder balance valve (5) includes a second pilot valve (51) and a straight-through oil passage (52). The second pilot valve (51) connects the rod chamber of the outer telescopic cylinder (1) and the rodless chamber of the inner telescopic cylinder (2). The straight-through oil passage (52) connects the rod chamber of the inner telescopic cylinder (2) and the first pilot valve (63) of the intermediate balance valve (6). The pilot oil passage of the second pilot valve (51) is provided with a relief valve (53), an adjustable flow valve (54), and a second check valve (55) connected in parallel.

5. The dual-cylinder hydraulic synchronous control system according to claim 1, characterized in that: The outer telescopic cylinder (1) and the inner telescopic cylinder (2) are respectively provided with mechanically triggered one-way valves (7) that connect the rod chamber and the rodless chamber. The triggering mechanism of the mechanically triggered one-way valve (7) is located at the bottom of the cylinder piston and is triggered by contact with the bottom of the cylinder body.

6. A high-altitude work equipment, characterized in that, The system includes a dual-cylinder hydraulic synchronous control system as described in any one of claims 1 to 4. The dual-cylinder hydraulic synchronous control system is used to drive the rod chamber of the outer telescopic cylinder (1) and the inner telescopic cylinder (2) to move synchronously and extend and retract, while cutting off the oil circuit of the rod chamber of the inner telescopic cylinder (2) when the system is locked.

7. The aerial work platform according to claim 6, characterized in that: The system includes a dual-cylinder hydraulic synchronous control system as described in claim 5, wherein the outer telescopic cylinder (1) and the inner telescopic cylinder (2) are respectively provided with mechanically triggered check valves (7) that connect the rod chamber and the rodless chamber. The triggering mechanism of the mechanically triggered check valves (7) is located at the bottom of the cylinder piston and is triggered by contact with the bottom of the cylinder body.

8. The aerial work platform according to claim 6, characterized in that: The aerial work equipment is a telescopic boom forklift.

9. The aerial work platform according to claim 8, characterized in that: The telescopic boom consists of a first-stage boom, a second-stage boom, and a third-stage boom nested in sequence. The outer telescopic cylinder (1) is installed outside the first-stage boom to drive the second-stage boom to telescopically extend relative to the first-stage boom. The inner telescopic cylinder (2) is fitted inside the second-stage boom to drive the third-stage boom to telescopically extend relative to the second-stage boom.

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