Hydraulic system for protecting a drive device of an aerial vehicle

Abstract

This invention discloses a hydraulic system for protecting the drive unit of an aerial work platform, relating to the field of engineering machinery technology. It includes: a hydraulic oil tank, a shut-off valve, a hydraulic pump, a filter, a solenoid relief valve, an electro-proportional directional valve, an integrated valve assembly, a hydraulic motor, a drive valve assembly, a steering cylinder, and a protection valve assembly. One end of the hydraulic oil tank is connected to one end of the shut-off valve, the other end of the shut-off valve is connected to one end of the hydraulic pump, the other end of the hydraulic pump is connected to one end of the filter, and the other end of the filter is connected to one end of the solenoid relief valve and the input end of the electro-proportional directional valve. The output end of the electro-proportional directional valve is connected to the input ends of the integrated valve assembly, the drive valve assembly, the steering cylinder, and the protection valve assembly. The output end of the drive valve assembly is connected to multiple hydraulic motors. This invention shortens the hydraulic oil transmission path and reduces pressure loss along the path, reduces energy waste under no-load and light-load conditions, and extends the service life of hydraulic components and mechanical structures.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and more specifically, to a hydraulic system for protecting the drive device of an aerial work platform. Background Technology

[0002] Aerial work platforms are widely used in construction, power, and municipal engineering fields. Their core function is to safely and efficiently transport personnel and tools to designated heights via a lifting mechanism. These platforms typically consist of a chassis system, lifting mechanism, work platform, power system, and control system. The chassis, as the supporting foundation of the entire vehicle, directly impacts operational safety due to its stability and maneuverability. Common chassis are modified from established automotive brands, equipped with frames, axles, and suspension systems to adapt to complex road conditions. Lifting mechanisms are categorized into scissor lifts, telescopic boom lifts, and folding boom lifts based on operational needs. Scissor lifts are simple in structure and have high load-bearing capacity, telescopic boom lifts offer high flexibility, and folding boom lifts can traverse obstacles to achieve wide-area operations. The work platform, as the direct working area, must meet high-strength and fall-prevention safety requirements. Some high-end models also feature automatic leveling to adapt to terrain changes.

[0003] Traditional aerial work platforms typically use hydraulic transmission systems for their drive systems, such as... Figure 1 As shown, the internal combustion engine drives a hydraulic pump to generate power, which is then used by four independent hydraulic motors to drive the reduction gears at the front and rear ends of the chassis to achieve movement. While this design simplifies the transmission structure and enables stepless speed regulation, it has significant drawbacks in practical applications. First, the uneven distribution of friction among the four wheels during stationary turning causes the steering cylinder to bear extreme stress, necessitating an increase in cylinder diameter and reinforcement of the welding strength of the steering pivot point. This not only increases manufacturing costs but also burdens the mechanical structure. Second, when driving on rough roads, the wheels lack dynamic coordination due to independent drive, and frequent turning can easily lead to loosening or even breakage of the wheel hub bolts, seriously affecting the safety and service life of the equipment.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0005] In view of the problems in related technologies, the present invention proposes a hydraulic system for the protection of the drive device of an aerial work platform, so as to overcome the above-mentioned technical problems existing in the existing related technologies.

[0006] Therefore, the specific technical solution adopted by the present invention is as follows:

[0007] A hydraulic system for protecting the drive unit of an aerial work platform includes: a hydraulic oil tank, a shut-off valve, a hydraulic pump, a filter, a solenoid relief valve, an electro-proportional directional valve, an integrated valve assembly, a hydraulic motor, a drive valve assembly, a steering cylinder, and a protection valve assembly.

[0008] The hydraulic oil tank is connected to one end of a shut-off valve, the shut-off valve is connected to one end of a hydraulic pump, the hydraulic pump is connected to one end of a filter, the filter is connected to one end of a solenoid relief valve and the input end of an electro-proportional directional valve, the output end of the electro-proportional directional valve is connected to the input end of an integrated valve group, the input end of a drive valve group, the input end of a steering cylinder and the input end of a protection valve group, and the output end of the drive valve group is connected to multiple hydraulic motors.

[0009] Furthermore, the electro-proportional directional valve includes: a first directional valve and a second directional valve.

[0010] Specifically, the main hydraulic oil inlet of the first directional valve is connected to the main hydraulic oil inlet of the second directional valve and serves as the P port of the electro-proportional directional valve; the main return port of the first directional valve is connected to the main return port of the second directional valve and serves as the T port of the electro-proportional directional valve; the two actuator interfaces of the first directional valve serve as the B2 port and A2 port of the electro-proportional directional valve, respectively; and the two actuator interfaces of the second directional valve serve as the B1 port and A1 port of the electro-proportional directional valve, respectively.

[0011] Furthermore, the integrated valve assembly includes: a first solenoid valve, a second solenoid valve, a first pressure reducing valve, a first relief valve, and a first shuttle valve;

[0012] The first relief valve is connected at one end to the return port of the first pressure reducing valve, one end of the first solenoid valve, one end of the second solenoid valve, the T port of the electro-proportional directional valve, and the T port of the solenoid relief valve. The other end of the first relief valve is connected to one end of the first pressure reducing valve. The other end of the first relief valve is connected to one end of the first pressure reducing valve, the return ports of the first solenoid valve and the second solenoid valve. The other end of the first pressure reducing valve is connected to one end of the first shuttle valve and the A2 port of the electro-proportional directional valve. The other end of the first shuttle valve is connected to the B2 port of the electro-proportional directional valve. The other end of the first solenoid valve leads out to ports K1 and K2. The other end of the second solenoid valve leads out to ports C1 and C2.

[0013] Furthermore, both the first and second directional control valves are three-position four-way directional control valves; both the first and second solenoid valves are two-position four-way solenoid directional control valves.

[0014] Furthermore, the hydraulic motors include: a first hydraulic motor, a second hydraulic motor, a third hydraulic motor, and a fourth hydraulic motor; and the first hydraulic motor, the second hydraulic motor, the third hydraulic motor, and the fourth hydraulic motor are all bidirectional fixed displacement hydraulic motors; the steering cylinders include: a first steering cylinder and a second steering cylinder;

[0015] Furthermore, the drive valve assembly includes: a first balancing valve, a second balancing valve, a first flow divider / combiner valve, a second flow divider / combiner valve, and a third flow divider / combiner valve;

[0016] The first balance valve is connected at one end to port A2 of the electro-proportional directional valve, and the second balance valve is connected at one end to port B2 of the electro-proportional directional valve. The other end of the first balance valve is connected to the oil inlet of the first flow divider / combiner valve. The two outlets of the first flow divider / combiner valve are respectively connected to the oil inlets of the second and third flow divider / combiner valves. The first outlet of the second flow divider / combiner valve is respectively connected to the second outlet of the second flow divider / combiner valve, port M3 of the first hydraulic motor, and port M7 of the third hydraulic motor. The return port of the fourth hydraulic motor, the T port of the electromagnetic relief valve, the M8 port of the fourth hydraulic motor, the return port of the third hydraulic motor, the return port of the first hydraulic motor, the return port of the second hydraulic motor, the first outlet port of the third flow divider and combiner valve, the second outlet port of the third flow divider and combiner valve, and the M4 port of the second hydraulic motor are connected; the other end of the second balance valve is connected to the M5 port of the third hydraulic motor, the M1 port of the first hydraulic motor, the M2 port of the second hydraulic motor, and the M6 ​​port of the fourth hydraulic motor, respectively.

[0017] Furthermore, the protection valve assembly includes: a damper, a second shuttle valve, a second relief valve, a second pressure reducing valve, and a third shuttle valve;

[0018] The damper is connected to one end of the second shuttle valve and serves as port C of the protection valve group. The other end of the damper is connected to the other end of the second shuttle valve, one end of the second relief valve, and one end of the second pressure reducing valve and serves as port K of the protection valve group. The other end of the second relief valve is connected to the return port of the second pressure reducing valve and serves as port T of the protection valve group. The other end of the second pressure reducing valve is connected to one end of the third shuttle valve and serves as port B of the protection valve group. The other end of the third shuttle valve serves as port A of the protection valve group.

[0019] Furthermore, the B1 port of the electro-proportional directional valve is connected to one end of the first steering cylinder, one end of the second steering cylinder, and the B port of the protection valve group, respectively, and the A1 port of the electro-proportional directional valve is connected to the other end of the first steering cylinder, the other end of the second steering cylinder, and the A port of the protection valve group, respectively.

[0020] Furthermore, the C port of the protection valve group is connected to the C1 and C2 ports of the second solenoid valve, the brake of the first hydraulic motor, and the brake of the third hydraulic motor, respectively, and the K port of the protection valve group is connected to the brake of the second hydraulic motor and the brake of the fourth hydraulic motor, respectively.

[0021] The K1 port of the first solenoid valve is connected to the drain port of the first hydraulic motor and the drain port of the third hydraulic motor, respectively; the K2 port of the first solenoid valve is connected to the drain port of the second hydraulic motor and the drain port of the fourth hydraulic motor, respectively.

[0022] Furthermore, the T port of the protection valve assembly is connected to the T port of the electro-proportional directional valve, the T port of the solenoid relief valve, and the T port of the integrated valve assembly, respectively.

[0023] The beneficial effects of this invention are as follows: it achieves significant energy-saving effects by reducing system pressure and total power; it adopts distributed drive and multi-valve group coordinated control, shortens the hydraulic oil transmission path and reduces pressure loss along the way, reducing energy waste under no-load and light-load conditions; through the linkage control of the protection valve group and the brake, the hydraulic lock of the steering wheel is automatically released when the steering command is triggered, so that the contact mode between the tire and the ground changes from static friction to rolling friction, which greatly reduces steering resistance and mechanical impact, thereby reducing energy consumption while extending the service life of hydraulic components and mechanical structures, reducing maintenance frequency and improving equipment operation stability, taking into account both environmental benefits and economy. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the original driving principle according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the working principle of a hydraulic system for protecting a high-altitude vehicle drive device according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of a protective valve group in a hydraulic system for protecting a high-altitude vehicle drive device according to an embodiment of the present invention.

[0028] In the picture:

[0029] 1. Hydraulic oil tank; 2. Shut-off valve; 3. Hydraulic pump; 4. Filter; 5. Solenoid relief valve; 6. Electro-proportional directional valve; 7. Integrated valve assembly; 8. Hydraulic motor; 9. Drive valve assembly; 10. Steering cylinder; 11. Protection valve assembly. Detailed Implementation

[0030] According to an embodiment of the present invention, a hydraulic system for protecting the drive device of an aerial work platform is provided.

[0031] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figures 2-3 As shown, the hydraulic system for protecting the aerial work platform drive device according to an embodiment of the present invention includes:

[0032] 1. Hydraulic oil tank; 2. Shut-off valve; 3. Hydraulic pump; 4. Filter; 5. Solenoid relief valve; 6. Electro-proportional directional valve; 7. Integrated valve assembly; 8. Hydraulic motor; 9. Drive valve assembly; 10. Steering cylinder; and 11. Protection valve assembly.

[0033] The hydraulic oil tank 1 is connected to one end of the shut-off valve 2, the other end of the shut-off valve 2 is connected to one end of the hydraulic pump 3, the other end of the hydraulic pump 3 is connected to one end of the filter 4, the other end of the filter 4 is connected to one end of the solenoid relief valve 5 and the input end of the electro-proportional directional valve 6, the output end of the electro-proportional directional valve 6 is connected to the input end of the integrated valve group 7, the input end of the drive valve group 9, the input end of the steering cylinder 10 and the input end of the protection valve group 11, and the output end of the drive valve group 9 is connected to multiple hydraulic motors 8.

[0034] In one embodiment, the electro-proportional directional valve 6 includes: a first directional valve (such as...) Figure 2 As shown, based on the characteristics of the three-position four-way directional control valve, the first directional control valve is labeled as SV3 and SV4 in the attached diagram, and the second directional control valve (as shown) is labeled as SV4 and SV5 respectively. Figure 2 As shown in the attached drawings, the second directional valves are labeled SV5 and SV6.

[0035] Specifically, the main hydraulic oil inlet of the first directional valve is connected to the main hydraulic oil inlet of the second directional valve and serves as the P port of the electro-proportional directional valve 6; the main return port of the first directional valve is connected to the main return port of the second directional valve and serves as the T port of the electro-proportional directional valve 6; the two actuator interfaces of the first directional valve serve as the B2 port and A2 port of the electro-proportional directional valve 6, respectively; and the two actuator interfaces of the second directional valve serve as the B1 port and A1 port of the electro-proportional directional valve 6, respectively.

[0036] In one embodiment, the integrated valve group 7 includes: a first solenoid valve SV1, a second solenoid valve SV2, a first pressure reducing valve, a first relief valve, and a first shuttle valve;

[0037] The first relief valve is connected at one end to the return port of the first pressure reducing valve, one end of the first solenoid valve SV1, one end of the second solenoid valve SV2, the T port of the electro-proportional directional valve 6, and the T port of the solenoid relief valve 5. The other end of the first relief valve is connected to one end of the first pressure reducing valve. The other end of the first relief valve is connected to one end of the first pressure reducing valve, the return ports of the first solenoid valve SV1 and the second solenoid valve SV2. The other end of the first pressure reducing valve is connected to one end of the first shuttle valve and the A2 port of the electro-proportional directional valve 6. The other end of the first shuttle valve is connected to the B2 port of the electro-proportional directional valve 6. The other end of the first solenoid valve SV1 leads out to ports K1 and K2. The other end of the second solenoid valve SV2 leads out to ports C1 and C2.

[0038] In one embodiment, both the first directional valve and the second directional valve are three-position four-way directional valves; both the first solenoid valve SV1 and the second solenoid valve SV2 are two-position four-way solenoid directional valves.

[0039] In one embodiment, the hydraulic motor 8 includes: a first hydraulic motor L1, a second hydraulic motor L2, a third hydraulic motor L3, and a fourth hydraulic motor L4; and the first hydraulic motor L1, the second hydraulic motor L2, the third hydraulic motor L3, and the fourth hydraulic motor L4 are all bidirectional fixed-displacement hydraulic motors; the steering cylinder 10 includes: a first steering cylinder and a second steering cylinder.

[0040] In one embodiment, the drive valve assembly 9 includes: a first balancing valve CV1, a second balancing valve CV2, a first flow divider / combiner valve F1, a second flow divider / combiner valve F2, and a third flow divider / combiner valve F3;

[0041] Specifically, one end of the first balance valve CV1 is connected to port A2 of the electro-proportional directional valve 6, one end of the second balance valve CV2 is connected to port B2 of the electro-proportional directional valve 6, and the other end of the first balance valve CV1 is connected to the oil inlet of the first flow divider / combiner valve F1. The two oil outlets of the first flow divider / combiner valve F1 are respectively connected to the oil inlets of the second flow divider / combiner valve F2 and the third flow divider / combiner valve F3. The first oil outlet of the second flow divider / combiner valve F2 is respectively connected to the second oil outlet of the second flow divider / combiner valve F2, port M3 of the first hydraulic motor L1, and port M7 of the third hydraulic motor L3. The return port of the fourth hydraulic motor L4, the T port of the electromagnetic relief valve 5, the M8 port of the fourth hydraulic motor L4, the return port of the third hydraulic motor L3, the return port of the first hydraulic motor L1, the return port of the second hydraulic motor L2, the first outlet port of the third diverter valve F3, the second outlet port of the third diverter valve F3, and the M4 port of the second hydraulic motor L2 are connected; the other end of the second balance valve CV2 is connected to the M5 port of the third hydraulic motor L3, the M1 port of the first hydraulic motor L1, the M2 port of the second hydraulic motor L2, and the M6 ​​port of the fourth hydraulic motor L4.

[0042] In one embodiment, the protection valve assembly 11 includes: a damper (attached) Figure 3 11.1), Second shuttle valve (attached) Figure 3 11.2), Second relief valve (attached) Figure 3 11.3), Second pressure reducing valve (attached) Figure 3 11.4) and the third shuttle valve (attached) Figure 3 (11.5)

[0043] The damper is connected to one end of the second shuttle valve and serves as port C of the protection valve group 11. The other end of the damper is connected to the other end of the second shuttle valve, one end of the second relief valve, and one end of the second pressure reducing valve and serves as port K of the protection valve group 11. The other end of the second relief valve is connected to the return port of the second pressure reducing valve and serves as port T of the protection valve group 11. The other end of the second pressure reducing valve is connected to one end of the third shuttle valve and serves as port B of the protection valve group 11. The other end of the third shuttle valve serves as port A of the protection valve group 11.

[0044] In one embodiment, the B1 port of the electro-proportional directional valve 6 is connected to one end of the first steering cylinder, one end of the second steering cylinder, and the B port of the protection valve group 11, respectively, and the A1 port of the electro-proportional directional valve 6 is connected to the other end of the first steering cylinder, the other end of the second steering cylinder, and the A port of the protection valve group 11, respectively.

[0045] In one embodiment, the C port of the protection valve assembly 11 is connected to the C1 and C2 ports of the second solenoid valve SV2, the brake of the first hydraulic motor L1, and the brake of the third hydraulic motor L3, respectively; the K port of the protection valve assembly 11 is connected to the brake of the second hydraulic motor L2 and the brake of the fourth hydraulic motor L4, respectively; the K1 port of the first solenoid valve SV1 is connected to the drain port of the first hydraulic motor L1 and the drain port of the third hydraulic motor L3, respectively; and the K2 port of the first solenoid valve SV1 is connected to the drain port of the second hydraulic motor L2 and the drain port of the fourth hydraulic motor L4, respectively.

[0046] In one embodiment, the T port of the protection valve assembly 11 is connected to the T port of the electro-proportional directional valve 6, the T port of the electromagnetic relief valve 5, and the T port of the integrated valve assembly 7, respectively.

[0047] To facilitate understanding of the above technical solutions of the present invention, the working principle or operation method of the present invention in actual process will be described in detail below.

[0048] In practical applications, depending on the usage scenario of the hydraulic system, it can be divided into driving forward, driving backward, high-speed driving, left steering, and right steering. The specific control methods are as follows:

[0049] 1. Driving Forward: The power source is started and the electromagnetic relief valve 5 is energized. The transmission mechanism drives the hydraulic pump 3, causing the closed volume of the hydraulic pump 3 to increase, creating a vacuum. Atmospheric pressure enters the hydraulic pump 3 through the hydraulic oil tank 1 and the shut-off valve 2. The hydraulic oil is squeezed out by the hydraulic pump 3, passes through the filter 4, and flows to the P port of the electro-proportional directional valve 6. After SV3 is energized, it flows to the A2 port of the electro-proportional directional valve 6 and then to the A port of the drive valve assembly 9. Within the drive valve assembly 9, it flows through the first balance valve CV1 while the second balance valve CV2 is opened, then to the first flow divider / combiner valve F1, and then to the second flow divider / combiner valve F2 and the third flow divider / combiner valve F3, and then to the M3, M4, M7, and M8 ports of each hydraulic motor 8. It then flows back through the M1, M2, M5, and M6 ports of the hydraulic motor 8 to the balance valve CV2, then to the B port of the drive valve assembly 9, and finally to the B2 port of the electro-proportional directional valve 6, then to the T port, returning to the hydraulic oil tank 1. During this period, when the SV3 of the electro-proportional directional valve 6 is energized, the SV2 electromagnet of the integrated valve group 7 needs to be energized to open the brake of the reducer.

[0050] Furthermore, in this invention, the hydraulic oil for steering wheel braking is opened by the shuttle valve of the protection valve group 11, and when closed, it flows back to the hydraulic oil tank 1 through the throttle port (T port) of the protection valve group 11.

[0051] 2. Drive Reverse: Simultaneously energize SV4 of the electro-proportional directional valve 6 and the second solenoid valve SV2 of the integrated valve group 7. Hydraulic oil flows from port P of the electro-proportional directional valve 6 to port B2, then to port B of the drive valve group 9. Within the drive valve group 9, the first balance valve CV1 is simultaneously opened via balance valve CV2, flowing to ports M1, M2, M5, and M6 of each hydraulic motor 8. The oil then flows through ports M3, M4, M7, and M8 of the hydraulic motors 8 to the second flow divider / combiner valve F2 and the third flow divider / combiner valve F3, before converging at the first flow divider / combiner valve F1. From there, it flows through the first balance valve CV1 to port A, then continues to port A2 of the electro-proportional directional valve 6, finally returning to the hydraulic oil tank 1 via port T.

[0052] 3. High-speed driving: During the forward and reverse driving process, the first solenoid valve SV1 electromagnet of the integrated valve group 7 is energized, so that the hydraulic motor 8 reaches the minimum displacement, and the hydraulic motor 8 rotates at high speed to achieve high-speed driving.

[0053] 4. Left Turn: When the SV5 electromagnet of the electro-proportional directional valve 6 is energized, hydraulic oil flows from port P to port A1 of the electro-proportional directional valve 6. After passing through the three-way valve, it flows to the rodless chamber of the first steering cylinder (left steering cylinder) and the rod chamber of the second steering cylinder (right steering cylinder). It then flows through the rod chamber of the left steering cylinder and the rodless chamber of the right steering cylinder to port B1 of the electro-proportional directional valve 6, and finally back to the hydraulic oil tank 1 via port T. Simultaneously, during steering, hydraulic oil enters port A or B of the protection valve assembly 11 from the steering cylinder 10, passes through the pressure reducing valve of the protection valve assembly 11, and then flows to port K, thereby flowing to the brake port of the deceleration mechanism to release the brake.

[0054] 5. Right Turn: When the SV6 solenoid of the electro-proportional directional valve 6 is energized, hydraulic oil flows from port P to port A1 of the electro-proportional directional valve 6. After passing through the three-way valve, it flows to the rodless chamber of the right steering cylinder and the rod chamber of the left steering cylinder, respectively. From the rod chamber of the right steering cylinder and the rodless chamber of the left steering cylinder, it flows to port B1 of the electro-proportional directional valve 6 and then back to port T, returning to the hydraulic oil tank 1. Simultaneously, during steering, hydraulic oil enters from the steering cylinder 10 into port A or B of the protection valve assembly 11. After passing through the pressure reducing valve of the protection valve assembly 11, it reaches port K, thus flowing to the brake port of the deceleration mechanism to release the brake.

[0055] Furthermore, in this invention, the control port K of the protection valve assembly 11 is connected to the front-wheel drive brake, port C is the control port after flow splitting, and A and B are the pressure ports of the rod-side and rodless-side chambers of the steering cylinder, respectively. When turning in place, the rod-side and rodless-side chambers of the steering cylinder are separately controlled by the third shuttle valve (i.e., attached...). Figure 3 11.5) flows into the second pressure reducing valve (attached) Figure 3 (11.4), via the second shuttle valve (attached) Figure 3 11.2) Enter the control oil port K to open the brake.

[0056] In summary, by utilizing the above-mentioned technical solution of this invention, significant energy-saving effects are achieved by reducing system pressure and total power. The use of distributed drive and multi-valve group coordinated control shortens the hydraulic oil transmission path and reduces pressure loss along the path, thus reducing energy waste under no-load and light-load conditions. Through the linkage control of the protection valve group and brake, the hydraulic lock of the steering wheel is automatically released when the steering command is triggered, changing the contact mode between the tire and the ground from static friction to rolling friction, significantly reducing steering resistance and mechanical impact. This reduces energy consumption while extending the service life of hydraulic components and mechanical structures, reducing maintenance frequency, and improving equipment operational stability, thus balancing environmental benefits and economic efficiency.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hydraulic system for protecting the drive device of an aerial work platform, characterized in that, include: Hydraulic oil tank (1), shut-off valve (2), hydraulic pump (3), filter (4), solenoid relief valve (5), electro-proportional directional valve (6), integrated valve group (7), hydraulic motor (8), drive valve group (9), steering cylinder (10) and protection valve group (11). Among them, one end of the hydraulic oil tank (1) is connected to one end of the shut-off valve (2), the other end of the shut-off valve (2) is connected to one end of the hydraulic pump (3), the other end of the hydraulic pump (3) is connected to one end of the filter (4), the other end of the filter (4) is connected to one end of the electromagnetic relief valve (5) and the input end of the electro-proportional directional valve (6), the output end of the electro-proportional directional valve (6) is connected to the input end of the integrated valve group (7), the input end of the drive valve group (9), the input end of the steering cylinder (10) and the input end of the protection valve group (11), and the output end of the drive valve group (9) is connected to multiple hydraulic motors (8). The hydraulic motor (8) includes: a first hydraulic motor, a second hydraulic motor, a third hydraulic motor and a fourth hydraulic motor; The steering cylinder (10) includes: a first steering cylinder and a second steering cylinder; The protection valve group (11) includes: a damper, a second shuttle valve, a second relief valve, a second pressure reducing valve, and a third shuttle valve; Wherein, one end of the damper is connected to one end of the second shuttle valve and serves as port C of the protection valve group (11); the other end of the damper is connected to the other end of the second shuttle valve, one end of the second relief valve and one end of the second pressure reducing valve and serves as port K of the protection valve group (11); the other end of the second relief valve is connected to the return port of the second pressure reducing valve and serves as port T of the protection valve group (11); the other end of the second pressure reducing valve is connected to one end of the third shuttle valve and serves as port B of the protection valve group (11); and the other end of the third shuttle valve serves as port A of the protection valve group (11). The B1 port of the electro-proportional directional valve (6) is connected to one end of the first steering cylinder, one end of the second steering cylinder and the B port of the protection valve group (11), respectively. The A1 port of the electro-proportional directional valve (6) is connected to the other end of the first steering cylinder, the other end of the second steering cylinder and the A port of the protection valve group (11), respectively. The C port of the protection valve group (11) is connected to the C1 port and C2 port of the second solenoid valve of the integrated valve group (7), the brake of the first hydraulic motor, and the brake of the third hydraulic motor, respectively. The K port of the protection valve group (11) is connected to the brake of the second hydraulic motor and the brake of the fourth hydraulic motor, respectively. The T port of the protection valve group (11) is connected to the T port of the electro-proportional directional valve (6), the T port of the electromagnetic relief valve (5), and the T port of the integrated valve group (7), respectively.

2. The hydraulic system for protecting the drive device of an aerial work platform according to claim 1, characterized in that, The electro-proportional directional valve (6) includes: a first directional valve and a second directional valve; Wherein, the main hydraulic oil inlet of the first directional valve is connected to the main hydraulic oil inlet of the second directional valve and serves as the P port of the electro-proportional directional valve (6), and the main return oil port of the first directional valve is connected to the main return oil port of the second directional valve and serves as the T port of the electro-proportional directional valve (6). The two actuator interfaces of the first directional valve are respectively used as the B2 port and A2 port of the electro-proportional directional valve (6), and the two actuator interfaces of the second directional valve are respectively used as the B1 port and A1 port of the electro-proportional directional valve (6).

3. The hydraulic system for protecting the drive device of an aerial work platform according to claim 2, characterized in that, The integrated valve group (7) includes: a first solenoid valve, a second solenoid valve, a first pressure reducing valve, a first relief valve, and a first shuttle valve; Wherein, one end of the first relief valve is connected to the oil return port of the first pressure reducing valve, one end of the first solenoid valve, one end of the second solenoid valve, the T port of the electro-proportional directional valve (6) and the T port of the solenoid relief valve (5), respectively, and the other end of the first relief valve is connected to one end of the first pressure reducing valve. The other end of the first relief valve is connected to the return oil ports of the first pressure reducing valve, the first solenoid valve, and the second solenoid valve, respectively. The other end of the first pressure reducing valve is connected to the first shuttle valve and the A2 port of the electro-proportional directional valve (6), respectively. The other end of the first shuttle valve is connected to the B2 port of the electro-proportional directional valve (6). The other end of the first solenoid valve leads out to ports K1 and K2, respectively, and the other end of the second solenoid valve leads out to ports C1 and C2, respectively.

4. The hydraulic system for protecting the drive device of an aerial work platform according to claim 3, characterized in that, Both the first reversing valve and the second reversing valve are three-position four-way reversing valves; Both the first and second solenoid valves are two-position four-way solenoid directional valves.

5. The hydraulic system for protecting the drive device of an aerial work platform according to claim 1, characterized in that, The first hydraulic motor, the second hydraulic motor, the third hydraulic motor, and the fourth hydraulic motor are all bidirectional fixed displacement hydraulic motors.

6. The hydraulic system for protecting the drive device of an aerial work platform according to claim 4, characterized in that, The drive valve group (9) includes: a first balancing valve, a second balancing valve, a first flow divider and combiner valve, a second flow divider and combiner valve, and a third flow divider and combiner valve; Wherein, one end of the first balance valve is connected to port A2 of the electro-proportional directional valve (6), one end of the second balance valve is connected to port B2 of the electro-proportional directional valve (6), the other end of the first balance valve is connected to the oil inlet of the first diverter valve, and the two oil outlets of the first diverter valve are respectively connected to the oil inlet of the second diverter valve and the oil inlet of the third diverter valve. The first oil outlet of the second diverter valve is connected to the second oil outlet of the second diverter valve, the M3 port of the first hydraulic motor, the M7 port of the third hydraulic motor, the return port of the fourth hydraulic motor, the T port of the electromagnetic relief valve (5), the M8 port of the fourth hydraulic motor, the return port of the third hydraulic motor, the return port of the first hydraulic motor, the return port of the second hydraulic motor, the first oil outlet of the third diverter valve, the second oil outlet of the third diverter valve, and the M4 port of the second hydraulic motor. The other end of the second balance valve is connected to the M5 port of the third hydraulic motor, the M1 port of the first hydraulic motor, the M2 port of the second hydraulic motor, and the M6 ​​port of the fourth hydraulic motor, respectively.

7. The hydraulic system for protecting the drive device of an aerial work platform according to claim 3, characterized in that, The K1 port of the first solenoid valve is connected to the drain port of the first hydraulic motor and the drain port of the third hydraulic motor, respectively; the K2 port of the first solenoid valve is connected to the drain port of the second hydraulic motor and the drain port of the fourth hydraulic motor, respectively.

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