Hydraulic system and aerial work platform

Abstract

The application relates to the technical field of hydraulic control, and provides a hydraulic system and an aerial work platform. The system comprises: a working oil circuit, which comprises a walking unit, a lifting unit, a steering unit, a walking valve group, a lifting valve group and a steering valve group; a pump group, which comprises a first bidirectional pump and a second bidirectional pump connected with the working oil circuit; a driving control unit, which comprises a motor and a controller connected with the motor, the walking valve group, the lifting valve group and the steering valve group to realize control; the lifting unit comprises a lifting oil cylinder, the lifting valve group controls the on-off between the rod cavity and the rodless cavity of the lifting oil cylinder and the first bidirectional pump; the steering unit comprises a steering oil cylinder, the steering valve group controls the on-off between the two rod cavities of the steering oil cylinder and the second bidirectional pump; the walking valve group comprises a pump valve group and a motor valve group to control the on-off between the first bidirectional pump and / or the second bidirectional pump and the walking unit via the pump valve group. The hydraulic system of the application has high applicability and stability.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic control technology, and in particular relates to a hydraulic system and an aerial work platform. Background Technology

[0002] As an important component of aerial work equipment, scissor lifts have gained a large market share in recent years due to their green and environmentally friendly features, flexible operation, and suitability for working in confined spaces.

[0003] Conventional scissor lift aerial work platforms typically employ either a single-pump, single-function travel system, where all functions share a large-displacement gear pump and the travel system uses a series connection of travel motors, adjusting speed via motor rotation. This results in relatively low driving torque and is only suitable for flat surfaces. Alternatively, they may use a single-pump, open-type travel system, which consumes more energy and uses solenoid valves to switch forward and backward movement. This system also has relatively low driving torque and is only suitable for indoor and flat ground operations. Furthermore, scissor lift aerial work platforms also have lifting and steering systems, both of which are driven by hydraulic systems. If the hydraulic system uses a single pump, and one of the travel, lifting, or steering systems is being driven by a hydraulic system, any simultaneous operation of another system will affect the hydraulic system's oil supply to that system, causing operational instability.

[0004] Therefore, there is a need to provide a hydraulic system that enables multi-speed drive of the walking unit, adapts to various application scenarios, and improves system stability. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a hydraulic system and an aerial work platform to solve the technical problems of the existing aerial work platform having a single walking mode, being unable to adapt to multiple application scenarios, and having insufficient system stability.

[0006] To solve the above-mentioned technical problems, the first aspect of this utility model provides a hydraulic system, comprising: The working oil circuit includes a travel unit, a lifting unit, a steering unit, a travel valve assembly, a lifting valve assembly, and a steering valve assembly; The pump set includes a first bidirectional pump and a second bidirectional pump connected to the working oil circuit; The drive control unit includes a motor for driving the first bidirectional pump and the second bidirectional pump, and a controller connected to the motor, the travel valve group, the lifting valve group and the steering valve group to realize control; The lifting unit includes a lifting cylinder, and the lifting valve group is configured to control the connection and disconnection between the first bidirectional pump and the rod-side and rodless-side chambers of the lifting cylinder. The steering unit includes a steering cylinder, and the steering valve assembly is configured to control the on / off connection between the second bidirectional pump and the two rod chambers of the steering cylinder; The travel valve assembly includes a pump valve assembly and a motor valve assembly, which control the connection and disconnection between the first bidirectional pump and / or the second bidirectional pump and the travel unit via the pump valve assembly.

[0007] In an embodiment of this utility model, the walking unit includes a first drive motor and a second drive motor, the pump valve group includes a first pump valve and a second pump valve, the first bidirectional pump is connected to the first drive motor and the second drive motor via the first pump valve, and the second bidirectional pump is connected to the first drive motor and the second drive motor via the second pump valve. The first pump valve is configured such that when it is in the first working position, the first bidirectional pump is not connected to the first drive motor and the second drive motor, and when it is in the second working position, the first bidirectional pump is connected to the first drive motor and the second drive motor. The second pump valve is configured such that when it is in the first operating position, the first bidirectional pump is not connected to the first drive motor and the second drive motor, and when it is in the second operating position, the first bidirectional pump is connected to the first drive motor and the second drive motor.

[0008] In an embodiment of this utility model, the lifting valve assembly includes a lifting on / off valve, and the first bidirectional pump is connected to the lifting cylinder and the first pump valve via the lifting on / off valve. The lifting on / off valve is configured such that when it is in the first working position, the first bidirectional pump is not connected to the lifting cylinder but is connected to the first pump valve; when it is in the second working position, the first bidirectional pump is connected to the lifting cylinder but is not connected to the first pump valve.

[0009] In an embodiment of this utility model, the drive control unit further includes a motor driver and a battery, both of which are connected to the controller, and the motor is connected to the controller and the battery via the motor driver; The lifting valve assembly further includes a cylinder control valve assembly disposed between the lifting on / off valve and the lifting cylinder. The cylinder control valve assembly is connected to the controller, and the cylinder control valve assembly is configured to control the selective communication between the rodless chamber of the lifting cylinder and the first bidirectional pump or oil tank. The controller is configured to detect whether the battery is allowed to be charged, and when the battery is allowed to be charged, control the cylinder control valve group to connect the rodless chamber of the lifting cylinder to the first bidirectional pump, and when the battery is not allowed to be charged, control the cylinder control valve group to connect the rodless chamber of the lifting cylinder to the oil tank.

[0010] In an embodiment of this utility model, the cylinder control valve group includes a return oil on / off valve, a one-way throttle valve, and a return oil selection valve; The return oil on / off valve is configured such that when it is in the first working position, the rodless chamber of the lifting cylinder does not return oil, and when it is in the second working position, the rodless chamber of the lifting cylinder returns oil. The one-way throttle valve throttles the flow in one direction from the return oil on / off valve to the first bidirectional pump or oil tank. The return oil selection valve is configured such that when it is in the first working position, the rodless chamber of the lifting cylinder is connected to the first bidirectional pump, and when it is in the second working position, the rodless chamber of the lifting cylinder is connected to the oil tank.

[0011] In an embodiment of this utility model, the steering valve assembly includes a steering return control valve and a steering reversing valve. The second bidirectional pump is connected to the steering cylinder via the steering reversing valve, and the steering return control valve is located between the second bidirectional pump and the steering reversing valve. The steering return control valve is configured such that when it is in the first operating position, the output end of the second bidirectional pump is connected to the oil tank, and when it is in the second operating position, the output end of the second bidirectional pump is connected to the steering reversing valve; and when the second pump valve is in the second operating position, the steering return control valve is in the first operating position. The steering valve is configured such that when it is in the first working position, the output end of the second bidirectional pump is not connected to the steering cylinder; when it is in the second working position, the output end of the second bidirectional pump is connected to the left rod chamber of the steering cylinder; and when it is in the third working position, the output end of the second bidirectional pump is connected to the right rod chamber of the steering cylinder.

[0012] In an embodiment of this utility model, the motor valve group includes a flow divider / combiner valve, a first motor selector valve, and a second motor selector valve; The first motor selection valve is configured to be closed when it is in the first operating position and open when it is in the second operating position; the second motor selection valve is configured to open when it is in the first operating position and close when it is in the second operating position. The series and parallel connection of the first drive motor and the second drive motor are controlled by selecting the on / off state of the first motor selection valve and the second motor selection valve.

[0013] In an embodiment of this utility model, the motor rotates forward, and the pressure oil output by the second bidirectional pump flows back to the oil tank through the first working position of the steering return oil control valve; the pressure oil output by the first bidirectional pump is divided into two paths after passing through the first working position of the lifting on / off valve, the second working position of the first pump valve, and the diversion and combination valve. One path flows into the first drive motor through the first working position of the second motor selection valve, and the other path flows directly into the second drive motor, so as to realize the first gear forward movement of the walking unit. When the motor reverses, the pressure oil output by the second bidirectional pump flows back to the oil tank through the first working position of the steering return oil control valve; the pressure oil output by the first bidirectional pump is divided into two paths after passing through the first working position of the lifting on / off valve and the second working position of the first pump valve. One path flows directly into the first drive motor, and the other path flows into the second drive motor through the first working position of the second motor selection valve, so as to realize the first gear reverse of the walking unit.

[0014] In an embodiment of this utility model, the motor rotates forward, and the pressure oil output by the second bidirectional pump flows back to the oil tank through the first working position of the steering return oil control valve; the pressure oil output by the first bidirectional pump is divided into two paths after passing through the first working position of the lifting on / off valve, the second working position of the first pump valve, and the diverting and combining valve, and then merges into one path through the second working position of the first motor selection valve and flows into the second drive motor; the oil discharge chamber of the second drive motor flows into the first drive motor through the second working position of the first motor selection valve, so as to realize the second gear forward movement of the walking unit; When the motor reverses, the pressure oil output by the second bidirectional pump flows back to the oil tank through the first working position of the steering return oil control valve; the pressure oil output by the first bidirectional pump flows into the first drive motor through the first working position of the lifting on / off valve and the second working position of the first pump valve; the oil discharge chamber of the first drive motor flows into the second drive motor through the second working position of the first motor selection valve, so as to realize the second gear reverse of the walking unit.

[0015] In an embodiment of this utility model, the motor rotates forward. When the motor rotates forward, the pressure oil output by the first bidirectional pump merges with the pressure oil output from the second bidirectional pump via the second working position of the second pump valve at the first working position of the lifting on / off valve. After merging, the oil is divided into two paths via the second working position of the first pump valve and the diverting and combining valve. One path flows into the first drive motor via the first working position of the second motor selection valve, and the other path flows directly into the second drive motor, thereby realizing the three-speed forward movement of the walking unit. When the motor reverses, the pressure oil output by the first bidirectional pump merges with the pressure oil output from the second bidirectional pump via the second working position of the second pump valve at the first working position of the lifting on / off valve. After passing through the second working position of the first pump valve, the oil is divided into two paths: one path flows directly into the first drive motor, and the other path flows into the second drive motor via the first working position of the second motor selection valve, thereby realizing the three-speed reverse of the walking unit.

[0016] In an embodiment of this utility model, when the motor rotates forward, the pressure oil output by the first bidirectional pump merges with the pressure oil output from the second bidirectional pump via the second working position of the lifting on / off valve at the first working position. After merging, the oil is divided into two paths via the second working position of the first pump valve and the diverting and combining valve. Then, the oil merges again via the second working position of the first motor selection valve into one path that flows into the second drive motor. The oil discharge chamber of the second drive motor flows into the first drive motor via the second working position of the first motor selection valve, thereby realizing the four-speed forward movement of the walking unit. When the motor reverses, the pressure oil output by the first bidirectional pump merges with the pressure oil output from the second bidirectional pump via the second working position of the second pump valve at the first working position of the lifting on / off valve. The oil then flows into the first drive motor via the second working position of the first pump valve. The oil discharge chamber of the first drive motor flows into the second drive motor via the second working position of the first motor selection valve, thereby realizing the four-speed reverse of the walking unit.

[0017] The second aspect of this utility model provides an aerial work platform, including the hydraulic system described in the above technical solution.

[0018] The beneficial effects of this utility model through the above solution are as follows: This invention uses a controller to control the number of oil pumps in the pump group that are connected to the traveling unit via a pump valve group, enabling the traveling unit to have multiple drive modes. This allows the aerial work platform of this application to adapt to more application scenarios. When driving the lifting unit or the steering unit alone, only one of the first and second bidirectional pumps is used, preventing both pumps from being under constant high load. This also extends the service life of the hydraulic system. Furthermore, it enables the first bidirectional pump to drive one of the traveling unit, lifting unit, and steering unit, while the second bidirectional pump drives the other. This avoids instability in the hydraulic system caused by the pump group simultaneously engaging one of the three pumps.

[0019] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the hydraulic principle of the hydraulic system of this utility model; Figure 2 This is a structural schematic diagram of the aerial work platform of this utility model.

[0021] Explanation of reference numerals in the attached figures 1. Motor; 2. First bidirectional pump; 3. Second bidirectional pump; 4. Two pumps, one check valve; 5. Two pumps, two check valves; 6. Second pump shuttle valve; 7. Steering return control valve; 8. Second pump relief valve; 9. Speed ​​limiter valve; 10. Steering reversing valve; 11. Steering cylinder; 12. First pump relief valve; 13. First pump shuttle valve; 14. One pump, one check valve; 15. One pump, two check valves; 16. Filter; 17. Hydraulic control valve; 18. Lifting on / off valve; 19. Hydraulic cylinder control valve assembly; 1901. Return oil on / off valve; 1902. One-way throttle valve; 1903. Return oil selection valve; 20. Lifting cylinder; 21. Rod-type one-way throttle valve; 22. Second pump valve; 23. First pump valve; 24. Diverter / combiner valve; 25. First motor selection valve; 26. Second motor selection valve; 27. First drive motor; 28. Second drive motor; 29. ​​Motor driver; 30. Battery; 31. Controller. Detailed Implementation

[0022] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of this utility model, and the protection scope of this utility model is not limited to the specific embodiments described below.

[0023] The hydraulic system and aerial work platform according to this utility model are described below with reference to the accompanying drawings.

[0024] See Figure 1 The first aspect of this utility model provides a hydraulic system including a working oil circuit, which includes a traveling unit, a lifting unit, a steering unit, a traveling valve group, a lifting valve group, and a steering valve group. The pump group includes a first bidirectional pump 2 and a second bidirectional pump 3 connected to the working oil circuit; the drive control unit includes a motor 1 for driving the pumps, and a controller 31 connected to the motor 1, the traveling valve group, the lifting valve group, and the steering valve group for control; the lifting unit includes a lifting cylinder 20, and the lifting valve group is configured to control the connection and disconnection between the pump group and the rod-side and rodless-side chambers of the lifting cylinder 20; the steering unit includes a steering cylinder 11, and the steering valve group is configured to control the connection and disconnection between the pump group and the two rod-side chambers of the steering cylinder 11; the traveling valve group includes a pump valve group and a motor valve group to control the connection and disconnection between the first bidirectional pump 2 and / or the second bidirectional pump 3 and the traveling unit via the pump valve group.

[0025] Based on the above basic embodiments, the controller 31 controls the number of oil pumps in the pump group that are connected to the traveling unit via the pump valve group, so that the traveling unit has multiple driving modes. This allows the aerial work platform of this application to adapt to more application scenarios. When driving the lifting unit or the steering unit alone, only one of the first bidirectional pump 2 and the second bidirectional pump 3 is used for driving, so that the first bidirectional pump 2 and the second bidirectional pump 3 will not be in a state of high load all the time. Therefore, the service life of the hydraulic system of this application can also be improved.

[0026] Furthermore, the walking unit includes a first drive motor 27 and a second drive motor 28, and the pump valve group includes a first pump valve 23 and a second pump valve 22. The first bidirectional pump 2 is connected to the first drive motor 27 and the second drive motor 28 via the first pump valve 23, and the second bidirectional pump 3 is connected to the first drive motor 27 and the second drive motor 28 via the second pump valve 22. Specifically, the first pump valve 23 is configured such that when it is in the first working position, the first bidirectional pump 2 is not connected to the first drive motor 27 and the second drive motor 28, and when it is in the second working position, the first bidirectional pump 2 is connected to the first drive motor 27 and the second drive motor 28; the second pump valve 22 is configured such that when it is in the first working position, the first bidirectional pump 2 is not connected to the first drive motor 27 and the second drive motor 28, and when it is in the second working position, the first bidirectional pump 2 is connected to the first drive motor 27 and the second drive motor 28, so that the first bidirectional pump 2 and the second bidirectional pump 3 can simultaneously supply oil to the first drive motor 27 and the second drive motor 28, so that the output of the pump set is higher and suitable for high-speed movement scenarios, or one of the first bidirectional pump 2 and the second bidirectional pump 3 supplies oil to the first drive motor 27 and the second drive motor 28, so that the output of the pump set is lower and suitable for low-speed movement scenarios.

[0027] See Figure 1 The lifting valve assembly includes a lifting on / off valve 18. The first bidirectional pump 2 is connected to the lifting cylinder 20 and the first pump valve 23 via the lifting on / off valve 18. The lifting on / off valve 18 is configured such that when it is in the first working position, the first bidirectional pump 2 is not connected to the lifting cylinder 20 but is connected to the first pump valve 23, and when it is in the second working position, the first bidirectional pump 2 is connected to the lifting cylinder 20 but is not connected to the first pump valve 23, thereby enabling the first bidirectional pump 2 to provide power to the lifting cylinder 20 independently.

[0028] Further, see Figure 1The drive control unit also includes a motor driver 29 and a battery 30, both of which are connected to the controller 31. The motor 1 is connected to the controller 31 and the battery 30 via the motor driver 29. The lifting valve assembly also includes a cylinder control valve assembly 19 located between the lifting on / off valve 18 and the lifting cylinder 20. The cylinder control valve assembly 19 is connected to the controller 31 and is configured to selectively control the connection between the rodless chamber of the lifting cylinder 20 and the first bidirectional pump 2 or the oil tank. The controller 31 is configured to detect whether the battery 30 is... When charging is permitted, the control cylinder control valve assembly 19 connects the rodless chamber of the lifting cylinder 20 to the first bidirectional pump 2. When charging is not permitted, the control cylinder control valve assembly 19 connects the rodless chamber of the lifting cylinder 20 to the oil tank. This allows the return oil from the lifting cylinder 20 to drive the motor to reverse and generate electricity to charge the battery 30 when charging is permitted, thus achieving energy recovery. When charging is not required, the return oil from the lifting cylinder 20 can directly enter the oil tank to prevent the battery 30 from being overcharged and damaged.

[0029] Specifically, the hydraulic cylinder control valve assembly 19 includes a return oil on / off valve 1901, a one-way throttle valve 1902, and a return oil selection valve 1903. The return oil on / off valve 1901 is configured such that when it is in the first working position, the rodless chamber of the lifting cylinder 20 does not return oil, and when it is in the second working position, the rodless chamber of the lifting cylinder 20 returns oil. The one-way throttle valve 1902 throttles in one direction from the return oil on / off valve 1901 to the first bidirectional pump 2 or the oil tank. The return oil selection valve 1903 is configured such that when it is in the first working position, the rodless chamber of the lifting cylinder 20 is connected to the first bidirectional pump 2, so that the return oil of the lifting cylinder 20 can drive the first bidirectional pump 2 to rotate, thereby driving the motor 1 to rotate and generate electricity, realizing energy recovery. When it is in the second working position, the rodless chamber of the lifting cylinder 20 is connected to the oil tank, so that the return oil of the lifting cylinder 20 is directly discharged into the oil tank without driving the motor 1 to generate electricity, thereby preventing the battery 30 from being overcharged.

[0030] Furthermore, the steering valve assembly includes a steering return control valve 7 and a steering reversing valve 10 connected to the controller 31. The second bidirectional pump 3 is connected to the steering cylinder 11 via the steering reversing valve 10. The steering return control valve 7 is located between the second bidirectional pump 3 and the steering reversing valve 10. The steering return control valve 7 is configured such that when it is in the first operating position, the output end of the second bidirectional pump 3 is connected to the oil tank to allow the second bidirectional pump 3 to idle. When it is in the second operating position, the output end of the second bidirectional pump 3 is connected to the steering reversing valve 10 to allow the second bidirectional pump 3 to idle. It can output power to the steering cylinder 11; and when the second pump valve 22 is in the second working position, the steering return oil control valve 7 is in the first working position, so as to prevent the second bidirectional pump 3 from idling when outputting power to the travel unit; the steering reversing valve 10 is configured such that when it is in the first working position, the output end of the second bidirectional pump 3 is not connected to the steering cylinder 11, when it is in the second working position, the output end of the second bidirectional pump 3 is connected to the left rod chamber of the steering cylinder 11, and when it is in the third working position, the output end of the second bidirectional pump 3 is connected to the right rod chamber of the steering cylinder 11. In the embodiments of this utility model, see Figure 1 and Figure 2 The motor valve assembly includes a flow divider / combiner valve 24, a first motor selector valve 25, and a second motor selector valve 26. The first motor selector valve 25 is configured to be closed when in a first operating position and open when in a second operating position. The second motor selector valve 26 is configured to be open when in the first operating position and closed when in the second operating position. The series and parallel connection of the first drive motor 27 and the second drive motor 28 are controlled by selecting the on / off state of the first motor selector valve 25 and the second motor selector valve 26, so that when the first drive motor 27 and the second drive motor 28 are connected in parallel, the walking unit moves at low speed and high torque, and when the first drive motor 27 and the second drive motor 28 are connected in series, the walking unit moves at high speed and low torque.

[0031] Based on the above-described mechanism, the operating conditions and corresponding control implementation principles of the hydraulic system in the first embodiment of this application are as follows: 1. Steering: 1-1. Left Turn: The controller 31 sends a signal, the steering return oil control valve 7 is energized and is in the second working position, the steering reversing valve 10 is energized and is in the third working position, the battery 30 and the motor driver 29 drive the motor 1 to rotate forward, the pressure oil of the first bidirectional pump 2 returns to the pump's suction port for idling through the first working position of the lifting on / off valve 18 and the first working position of the first pump valve 23, the second bidirectional pump 3 draws oil through the check valve, and the output pressure oil flows into the right rod chamber of the steering cylinder 11 through the third working position of the second pump shuttle valve 6, the speed limit valve 9 and the steering reversing valve 10, the oil in the left rod chamber of the steering cylinder 11 flows back to the oil tank through the third working position of the solenoid reversing valve, thus realizing left turn.

[0032] 1-2. Right Turn: The controller 31 sends a signal, the steering return oil control valve 7 is energized and is in the second working position, the steering reversing valve 10 is energized and is in the second working position, the battery 30 and the motor driver 29 drive the motor 1 to rotate forward, the pressure oil of the first bidirectional pump 2 returns to the pump's suction port for idling through the first working position of the lifting on / off valve 18 and the first working position of the first pump valve 23, the second bidirectional pump 3 draws oil through the check valve, and the output pressure oil flows into the left rod chamber of the steering cylinder 11 through the second working position of the second pump shuttle valve 6, the speed limit valve 9 and the steering reversing valve 10, and the oil in the right rod chamber of the steering cylinder 11 flows back to the oil tank through the second working position of the electromagnetic reversing valve, thus realizing right turn.

[0033] Understandably, the aforementioned second pump shuttle valve 6 is used to control the switching of the oil supply and return lines of the working oil circuit when the second bidirectional pump 3 rotates forward and backward, to prevent oil leakage between the supply and return lines that could cause instability in the hydraulic system. The speed limit valve 9 is used to control the flow rate of hydraulic oil to the steering valve 10, to prevent excessively fast steering leading to instability or difficulty in controlling steering accuracy. Furthermore, a second pump relief valve 8 can be installed between the speed limit valve 9 and the steering return control valve 7 to provide overflow and pressure relief protection for the oil circuit.

[0034] 2. Walking: 2-1. First Gear: Motor 1 rotates forward. The pressure oil output by the second bidirectional pump 3 flows back to the oil tank through the first working position of the steering return oil control valve 7. The first bidirectional pump 2 draws oil through the pump-one-check valve 14. The output pressure oil is divided into two paths after passing through the first working position of the lifting on-off valve 18, the second working position of the first pump valve 23, and the diversion and combination valve 24. One path flows into the first drive motor 27 through the first working position of the second motor selection valve 26, and the other path flows directly into the second drive motor 28. The first bidirectional pump 2 drives the first drive motor 27 and the second drive motor 28 in parallel to realize the first gear forward movement of the walking unit. At this time, the pressure oil pushes the hydraulic control valve 17 to move upward to the lower position. The pressure oil in the drain chambers of the first drive motor 27 and the second drive motor 28 flows back to the oil tank through the second working position of the first pump valve 23, the first working position of the lifting on-off valve 18, the hydraulic control valve 17, and the filter 16.

[0035] When motor 1 reverses, the pressure oil output by the second bidirectional pump 3 flows back to the oil tank through the first working position of the steering return oil control valve 7. The first bidirectional pump 2 draws oil through the pump-two-one-way valve 15. The output pressure oil is divided into two paths after passing through the first working position of the lifting on-off valve 18 and the second working position of the first pump valve 23. One path flows directly into the first drive motor 27, and the other path flows into the second drive motor 28 through the first working position of the second motor selection valve 26. The first bidirectional pump 2 drives the first drive motor 27 and the second drive motor 28 in parallel to realize the first gear reverse of the walking unit. At this time, the pressure oil pushes the hydraulic control valve 17 to move downward to the upper position. The pressure oil in the drain chamber of the first drive motor 27 is combined with the pressure oil in the drain chamber of the second drive motor 28 through the first working position of the second motor selection valve 26, the diversion and combination valve 24, and the second drive motor 28. The pressure oil then flows back to the oil tank through the second working position of the first pump valve 23, the first working position of the lifting on-off valve 18, the hydraulic control valve 17, and the filter 16.

[0036] The first bidirectional pump 2 drives the first drive motor 27 and the second drive motor 28 in parallel, enabling the walking unit to output at low speed and high torque, which is suitable for starting when climbing or under heavy load.

[0037] 2-2, Second Gear: Motor 1 rotates forward. The pressure oil output by the second bidirectional pump 3 flows back to the oil tank through the first working position of the steering return oil control valve 7. The first bidirectional pump 2 draws oil through the pump-one-check valve 14. The output pressure oil is divided into two paths after passing through the first working position of the lifting on-off valve 18, the second working position of the first pump valve 23, and the diversion and combination valve 24. Then, it merges into one path through the second working position of the first motor selection valve 25 and flows into the second drive motor 28. The oil discharge chamber of the second drive motor 28 flows into the first drive motor 27 through the second working position of the first motor selection valve 25. The first bidirectional pump 2 drives the first drive motor 27 and the second drive motor 28 in series to achieve the second gear forward movement of the walking unit. At this time, the pressure oil simultaneously pushes the hydraulic control valve 17 to move upward to the lower position. The pressure oil in the oil discharge chamber of the first drive motor 27 flows back to the oil tank through the second working position of the first pump valve 23, the first working position of the solenoid switch valve, the hydraulic control valve 17, and the filter 16.

[0038] When motor 1 reverses, the pressure oil output by the second bidirectional pump 3 flows back to the oil tank through the first working position of the steering return oil control valve 7. The first bidirectional pump 2 draws oil through the pump-two-one-way valve 15, and the output pressure oil flows into the first drive motor 27 through the first working position of the lifting on-off valve 18 and the second working position of the first pump valve 23. The oil discharge chamber of the first drive motor 27 flows into the second drive motor 28 through the second working position of the first motor selection valve 25. The first bidirectional pump 2 drives the first drive motor 27 and the second drive motor 28 in series to achieve the second-gear reverse of the walking unit. At this time, the pressure oil simultaneously pushes the hydraulic control valve 17 to move upward to the lower position. The pressure oil in the oil discharge chamber of the second drive motor 28 is divided into two paths. One path flows into the diversion and combination valve 24, and the other path flows into the diversion and combination valve 24 again through the second working position of the first motor selection valve 25. After being combined into one path, the oil flows back to the oil tank through the second working position of the first pump valve 23, the first working position of the lifting on-off valve 18, the hydraulic control valve 17, and the filter 16.

[0039] The first bidirectional pump 2 drives the first drive motor 27 and the second drive motor 28 in series, enabling the walking unit to output at high speed and low torque, which is suitable for quick start-up on flat ground or under low load conditions.

[0040] 2-3. Three-speed: Motor 1 rotates forward. The first bidirectional pump 2 draws oil through the pump-one-check valve 14, and the second bidirectional pump 3 draws oil through the pump-one-check valve 4. The pressure oil output from the first bidirectional pump 2 merges with the pressure oil from the second bidirectional pump 3 (from the second pump valve 22) at the first working position of the lifting on / off valve 18. After passing through the second working position of the first pump valve 23 and the diversion / combination valve 24, the oil is divided into two paths. One path flows into the first drive motor 27 through the first working position of the second motor selection valve 26, and the other path flows directly into the second drive motor 28. The first drive motor 27, which is in parallel operation, is driven by the first bidirectional pump 2 and the second bidirectional pump 3, thus achieving the three-speed forward movement of the walking unit. At the same time, the pressure oil pushes the hydraulic control valve 17 upward to its lower position. The pressure oil in the discharge chamber of the first drive motor 27 flows back to the oil tank through the second working position of the first pump valve 23, the first working position of the solenoid switch valve, the hydraulic control valve 17, and the filter 16.

[0041] When motor 1 reverses, the first bidirectional pump 2 draws oil through the first pump two-way valve 15, and the second bidirectional pump 3 draws oil through the second pump two-way valve 5. The pressure oil output by the first bidirectional pump 2 merges with the pressure oil output from the second bidirectional pump 3 through the second pump valve 22 at the first working position of the lifting on / off valve 18. After passing through the second working position of the first pump valve 23, the oil is divided into two paths. One path flows directly into the first drive motor 27, and the other path flows into the second drive motor 28 through the first working position of the second motor selection valve 26. The first drive motor 27 and the first drive motor 28 are driven in parallel by the first bidirectional pump 2 and the second bidirectional pump 3 to achieve the three-speed reverse of the walking unit. At this time, the pressure oil simultaneously pushes the hydraulic control valve 17 downward to the upper position. The pressure oil in the drain chamber of the first drive motor 27 is combined with the pressure oil in the drain chamber of the second drive motor 28 through the first working position of the second motor selection valve 26, the diversion and combination valve 24, and the second working position of the first pump valve 23, the first working position of the lifting on / off valve 18, the hydraulic control valve 17, and the filter 16, and flows back to the oil tank.

[0042] The first bidirectional pump 2 and the second bidirectional pump 3 drive the first drive motor 27 and the second drive motor 28 in parallel, enabling the walking unit to output at high speed and high torque, which is suitable for rapid start-up under flat ground conditions or heavy load conditions.

[0043] 2-4. Fourth gear: When motor 1 rotates forward, the first bidirectional pump 2 draws oil through the pump-one-check valve 14, and the second bidirectional pump 3 draws oil through the pump-one-check valve 4. The pressure oil output by the first bidirectional pump 2 merges with the pressure oil output from the second bidirectional pump 3 through the second pump valve 22 at the first working position of the lifting on / off valve 18. After merging, it is divided into two paths after passing through the second working position of the first pump valve 23 and the diverting and combining valve 24. Then, it merges into one path through the second working position of the first motor selection valve 25 and flows into the second drive motor 28. The oil discharge chamber of the second drive motor 28 flows into the first drive motor 27 through the second working position of the first motor selection valve 25. The first drive motor 27 and the first drive motor 28 in parallel state are driven by the first bidirectional pump 2 and the second bidirectional pump 3 to realize the four-speed forward movement of the walking unit. At this time, the pressure oil pushes the hydraulic control valve 17 upward to the lower position, and the pressure oil in the oil discharge chamber of the first drive motor 27 flows back to the oil tank through the second working position of the first pump valve 23, the first working position of the solenoid switch valve, the hydraulic control valve 17 and the filter 16.

[0044] When motor 1 reverses, the first bidirectional pump 2 draws oil through the first pump two-way valve 15, and the second bidirectional pump 3 draws oil through the second pump two-way valve 5. The pressure oil output by the first bidirectional pump 2 merges with the pressure oil output from the second bidirectional pump 3 through the second pump valve 22 at the first working position of the lifting on / off valve 18, and then flows into the first drive motor 27 through the second working position of the first pump valve 23. The oil discharge chamber of the first drive motor 27 flows into the second drive motor 28 through the second working position of the first motor selection valve 25, so that the first drive motor 27 and the first drive motor 28 in parallel state are driven by the first bidirectional pump 2 and the second bidirectional pump 3 to realize the four-speed reverse of the walking unit. At this time, the pressure oil simultaneously pushes the hydraulic control valve 17 upward to the lower position. The pressure oil in the oil discharge chamber of the second drive motor 28 is divided into two paths. One path flows into the diversion and combination valve 24, and the other path flows into the diversion and combination valve 24 again through the second working position of the first motor selection valve 25. After the oil is combined into one path, it flows back to the oil tank through the second working position of the first pump valve 23, the first working position of the lifting on / off valve 18, the hydraulic control valve 17, and the filter 16.

[0045] The first bidirectional pump 2 and the second bidirectional pump 3 drive the first drive motor 27 and the second drive motor 28 in parallel, enabling the walking unit to output at high speed and low torque, reaching the maximum output speed, which is suitable for rapid transfer on flat ground or rapid start under low load conditions.

[0046] 3. Lifting: Motor 1 rotates forward, and the second bidirectional pump 3 rotates forward to draw oil from the second pump-one-one-valve 4. The output pressure oil returns to the oil tank through the second pump shuttle valve 6 and the lower position of the steering return oil control valve 7. The first bidirectional pump 2 draws oil through the first pump-one-one-valve 14. The output pressure oil passes through the first pump shuttle valve 13 and then flows into the rodless chamber of the lifting cylinder 20 through the second working position of the lifting on / off valve 18, the one-way throttle valve 1902 in the cylinder control valve, and the return oil on / off valve 1901. At the same time, the pressure oil pushes the hydraulic control valve 17 to move upward to the lower position. Part of the pressurized oil in the rod chamber of the lifting cylinder 20 flows back to the oil tank in a small amount through the rod chamber one-way throttle valve 21, and the other part flows to the first bidirectional suction side or back to the oil tank through the lifting on / off valve 18, so that the piston rod of the lifting cylinder 20 extends to lift the aerial work platform. Part of the pressurized oil flowing out of the rod chamber can flow to the suction side of the first bidirectional pump 2, which can play a certain role in energy recovery and utilization.

[0047] 4. Lowering: The controller 31 determines whether charging of the battery 30 is permitted by monitoring the battery 30 status (e.g., monitoring the voltage of the battery 30 to determine its charge level, and then determining whether charging is permitted based on the percentage of charge level; this is based on existing technology and will not be elaborated here). If charging is permitted, the controller 31 sends a signal, the lifting on / off valve 18 is energized and placed in the second working position, the return oil selection valve 1903 is de-energized and placed in the first working position, and the return oil on / off valve 1901 in the cylinder control valve group 19 is energized and placed in the second working position. Under the action of gravity, the cylinder 2 is lifted. When the hydraulic rod of the lifting cylinder 20 retracts, the pressure oil in the rodless chamber of the lifting cylinder 20 flows back to the oil tank through the second working position of the return oil on / off valve 1901, the one-way throttle valve 1902, the second working position of the lifting on / off valve 18, the first bidirectional pump 2, and the lower position of the hydraulic control valve 17. During this process, the pressure oil drives the first bidirectional pump 2 to rotate in the opposite direction, thereby driving the motor 1 to rotate and generate electricity. The controller 31 adjusts the current direction of the motor driver 29 so that the current generated by the motor 1 flows to the battery 30 to charge it. The rod chamber of the lifting cylinder 20 draws oil from the oil tank and replenishes it through the rod chamber one-way throttle valve 21 and the return oil line.

[0048] If the controller 31 determines that the battery 30 is not allowed to be charged, it sends a control signal. The solenoid valve in the cylinder control valve group 19 is energized to be in the first working position, and the return oil selection valve 1903 is energized to be in the second working position. The pressure oil in the rodless chamber of the lifting cylinder 20 flows back to the oil tank through the first working position of the return oil on / off valve 1901, the one-way throttle valve 1902, the second working position of the return oil selection valve 1903, and the one-way throttle valve 21 in the rod chamber.

[0049] The second aspect of this utility model provides an aerial work platform, which includes the hydraulic system described above, and therefore also has all the technical effects of the hydraulic system described above.

[0050] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0051] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "forming," "having," "setting," and "connecting," etc., should be interpreted broadly. For example, a connection can be a direct connection or an indirect connection through an intermediate medium; it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate connecting member; it can be the internal communication of two components or the interaction between two components. Those skilled in the art can understand the above terms in this utility model according to the specific circumstances.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0054] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.

[0055] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.

Claims

1. A hydraulic system, characterized in that, include: The working oil circuit includes a travel unit, a lifting unit, a steering unit, a travel valve assembly, a lifting valve assembly, and a steering valve assembly; The pump set includes a first bidirectional pump (2) and a second bidirectional pump (3) connected to the working oil circuit. The drive control unit includes a motor (1) for driving the first bidirectional pump (2) and the second bidirectional pump (3), and a controller (31) connected to the motor (1), the travel valve group, the lifting valve group and the steering valve group to realize control. The lifting unit includes a lifting cylinder (20), and the lifting valve group is configured to control the connection and disconnection between the rod chamber and the rodless chamber of the first bidirectional pump (2) and the lifting cylinder (20); The steering unit includes a steering cylinder (11), and the steering valve assembly is configured to control the connection and disconnection between the second bidirectional pump (3) and the two rod chambers of the steering cylinder (11); The travel valve group includes a pump valve group and a motor valve group to control the on / off connection between the first bidirectional pump (2) and / or the second bidirectional pump (3) and the travel unit via the pump valve group.

2. The hydraulic system according to claim 1, characterized in that, The walking unit includes a first drive motor (27) and a second drive motor (28), and the pump valve group includes a first pump valve (23) and a second pump valve (22). The first bidirectional pump (2) is connected to the first drive motor (27) and the second drive motor (28) via the first pump valve (23), and the second bidirectional pump (3) is connected to the first drive motor (27) and the second drive motor (28) via the second pump valve (22). The first pump valve (23) is configured such that when it is in the first working position, the first bidirectional pump (2) is not connected to the first drive motor (27) and the second drive motor (28), and when it is in the second working position, the first bidirectional pump (2) is connected to the first drive motor (27) and the second drive motor (28); The second pump valve (22) is configured such that when it is in the first working position, the first bidirectional pump (2) is not connected to the first drive motor (27) and the second drive motor (28), and when it is in the second working position, the first bidirectional pump (2) is connected to the first drive motor (27) and the second drive motor (28).

3. The hydraulic system according to claim 2, characterized in that, The lifting valve assembly includes a lifting on / off valve (18), and the first bidirectional pump (2) is connected to the lifting cylinder (20) and the first pump valve (23) via the lifting on / off valve (18). The lifting on / off valve (18) is configured such that when it is in the first working position, the first bidirectional pump (2) is not connected to the lifting cylinder (20) but is connected to the first pump valve (23), and when it is in the second working position, the first bidirectional pump (2) is connected to the lifting cylinder (20) but is not connected to the first pump valve (23).

4. The hydraulic system according to claim 3, characterized in that, The drive control unit further includes a motor driver (29) and a battery (30), both of which are connected to the controller (31), and the motor (1) is connected to the controller (31) and the battery (30) via the motor driver (29); The lifting valve assembly also includes a cylinder control valve assembly (19) located between the lifting on / off valve (18) and the lifting cylinder (20). The cylinder control valve assembly (19) is connected to the controller (31), and the cylinder control valve assembly (19) is configured to control the selective communication between the rodless chamber of the lifting cylinder (20) and the first bidirectional pump (2) or the oil tank. The controller (31) is configured to detect whether the battery (30) is allowed to be charged, and when the battery (30) is allowed to be charged, control the cylinder control valve group (19) to connect the rodless chamber of the lifting cylinder (20) to the first bidirectional pump (2), and when the battery (30) is not allowed to be charged, control the cylinder control valve group (19) to connect the rodless chamber of the lifting cylinder (20) to the oil tank.

5. The hydraulic system according to claim 4, characterized in that, The cylinder control valve group (19) includes a return oil on / off valve (1901), a one-way throttle valve (1902), and a return oil selection valve (1903). The return oil on / off valve (1901) is configured such that when it is in the first working position, the rodless chamber of the lifting cylinder (20) does not return oil, and when it is in the second working position, the rodless chamber of the lifting cylinder (20) returns oil. The one-way throttle valve (1902) throttles the flow in one direction from the return oil on / off valve (1901) to the first bidirectional pump (2) or the oil tank; The return oil selection valve (1903) is configured such that when it is in the first working position, the rodless chamber of the lifting cylinder (20) is connected to the first bidirectional pump (2), and when it is in the second working position, the rodless chamber of the lifting cylinder (20) is connected to the oil tank.

6. The hydraulic system according to any one of claims 3-5, characterized in that, The steering valve assembly includes a steering return control valve (7) and a steering reversing valve (10). The second bidirectional pump (3) is connected to the steering cylinder (11) via the steering reversing valve (10). The steering return control valve (7) is located between the second bidirectional pump (3) and the steering reversing valve (10). The steering return oil control valve (7) is configured such that when it is in the first working position, the output end of the second bidirectional pump (3) is connected to the oil tank, and when it is in the second working position, the output end of the second bidirectional pump (3) is connected to the steering reversing valve (10); and when the second pump valve (22) is in the second working position, the steering return oil control valve (7) is in the first working position; The steering valve (10) is configured such that when it is in the first working position, the output end of the second bidirectional pump (3) is not connected to the steering cylinder (11); when it is in the second working position, the output end of the second bidirectional pump (3) is connected to the left rod chamber of the steering cylinder (11); and when it is in the third working position, the output end of the second bidirectional pump (3) is connected to the right rod chamber of the steering cylinder (11).

7. The hydraulic system according to claim 6, characterized in that, The motor valve group includes a flow divider / combiner valve (24), a first motor selector valve (25), and a second motor selector valve (26). The first motor selection valve (25) is configured to be non-flowing when it is in the first working position and flowing when it is in the second working position; the second motor selection valve (26) is configured to flow when it is in the first working position and non-flowing when it is in the second working position. The series and parallel connection of the first drive motor (27) and the second drive motor (28) are controlled by selecting the on / off state of the first motor selection valve (25) and the second motor selection valve (26).

8. The hydraulic system according to claim 7, characterized in that, When the motor (1) rotates forward, the pressure oil output by the second bidirectional pump (3) flows back to the oil tank through the first working position of the steering return oil control valve (7); the pressure oil output by the first bidirectional pump (2) is divided into two paths after passing through the first working position of the lifting on / off valve (18), the second working position of the first pump valve (23), and the diversion and combination valve (24). One path flows into the first drive motor (27) through the first working position of the second motor selection valve (26), and the other path flows directly into the second drive motor (28) to realize the first gear forward movement of the walking unit. When the motor (1) reverses, the pressure oil output by the second bidirectional pump (3) flows back to the oil tank through the first working position of the steering return oil control valve (7); the pressure oil output by the first bidirectional pump (2) is divided into two paths after passing through the first working position of the lifting on / off valve (18) and the second working position of the first pump valve (23). One path flows directly into the first drive motor (27), and the other path flows into the second drive motor (28) through the first working position of the second motor selection valve (26), so as to realize the first gear reverse of the walking unit.

9. The hydraulic system according to claim 7, characterized in that, When the motor (1) rotates forward, the pressure oil output by the second bidirectional pump (3) flows back to the oil tank through the first working position of the steering return oil control valve (7); the pressure oil output by the first bidirectional pump (2) is divided into two paths after passing through the first working position of the lifting on / off valve (18), the second working position of the first pump valve (23), and the diversion and combination valve (24), and then merges into one path through the second working position of the first motor selection valve (25) and flows into the second drive motor (28). The oil discharge chamber of the second drive motor (28) flows into the first drive motor (27) through the second working position of the first motor selection valve (25) to realize the second gear forward movement of the walking unit; When the motor (1) reverses, the pressure oil output by the second bidirectional pump (3) flows back to the oil tank through the first working position of the steering return oil control valve (7); the pressure oil output by the first bidirectional pump (2) flows into the first drive motor (27) through the first working position of the lifting on / off valve (18) and the second working position of the first pump valve (23), and the oil discharge chamber of the first drive motor (27) flows into the second drive motor (28) through the second working position of the first motor selection valve (25) to realize the second gear reverse of the walking unit.

10. The hydraulic system according to claim 7, characterized in that, When the motor (1) rotates forward, the pressure oil output by the first bidirectional pump (2) merges with the pressure oil output from the second bidirectional pump (3) via the second working position of the second pump valve (22) after passing through the first working position of the lifting on / off valve (18). After passing through the second working position of the first pump valve (23) and the diversion and combination valve (24), the oil is divided into two paths. One path flows into the first drive motor (27) via the first working position of the second motor selection valve (26), and the other path flows directly into the second drive motor (28) to realize the three-speed forward movement of the walking unit. When the motor (1) reverses, the pressure oil output by the first bidirectional pump (2) merges with the pressure oil output by the second bidirectional pump (3) through the second pump valve (22) through the first working position of the lifting on / off valve (18). After merging, the pressure oil is divided into two paths after passing through the second working position of the first pump valve (23). One path flows directly into the first drive motor (27), and the other path flows into the second drive motor (28) through the first working position of the second motor selection valve (26), so as to realize the three-speed reverse of the walking unit.

11. The hydraulic system according to claim 7, characterized in that, When the motor (1) rotates forward, the pressure oil output by the first bidirectional pump (2) merges with the pressure oil output from the second bidirectional pump (3) via the second working position of the lifting on / off valve (18) and the pressure oil from the second pump valve (22) via the second working position of the second bidirectional pump (3). After passing through the second working position of the first pump valve (23) and the diversion and combination valve (24), the oil is divided into two paths and then merged into one path through the second working position of the first motor selection valve (25) and flows into the second drive motor (28). The oil discharge chamber of the second drive motor (28) flows into the first drive motor (27) through the second working position of the first motor selection valve (25) to realize the four-speed forward movement of the walking unit. When the motor (1) reverses, the pressure oil output by the first bidirectional pump (2) merges with the pressure oil output from the second bidirectional pump (3) via the second working position of the second pump valve (22) at the first working position of the lifting on / off valve (18), and then flows into the first drive motor (27) via the second working position of the first pump valve (23). The oil discharge chamber of the first drive motor (27) flows into the second drive motor (28) via the second working position of the first motor selection valve (25), so as to realize the four-speed reverse of the walking unit.

12. An aerial work platform, characterized in that, Includes the hydraulic system as described in any one of claims 1 to 11.

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