Boom luffing hydraulic control system and aerial work platform

Abstract

The application discloses an arm frame luffing hydraulic control system and an aerial work platform, and relates to the field of hydraulic systems. The arm frame luffing hydraulic control system comprises an oil tank, an oil supply unit, a multi-way valve group and a luffing oil cylinder, and further comprises a pump motor, a motor generator, a battery unit and a switching valve group. In a self-weight luffing down mode, a rodless cavity of the luffing oil cylinder is connected to the oil tank through the switching valve group and the multi-way valve group. In an emergency luffing down mode, a second working port of the pump motor is connected to a rod cavity of the luffing oil cylinder through the switching valve group and the multi-way valve group, the pump motor is in a pump working condition, and the motor generator is in a motor mode. In a self-weight luffing down potential energy recovery mode, the rodless cavity of the luffing oil cylinder is connected to the second working port of the pump motor through the switching valve group, the pump motor is in a motor working condition, and the motor generator is in a generator mode. At least part of the gravitational potential energy released when the arm frame is lowered can be converted into electrical energy for recovery and storage, thereby reducing the energy originally completely consumed by proportional throttling.

Description

Technical Field

[0001] This invention relates to the field of hydraulic systems, and in particular to a boom luffing hydraulic control system and an aerial work platform. Background Technology

[0002] As crucial engineering machinery, aerial work platforms require frequent lifting, luffing, and slewing movements of their booms. For electric aerial work platforms, the overall range is directly related to the energy utilization efficiency of the power battery. During the boom's descent from a high to a low position, a considerable amount of gravitational potential energy is released. How to rationally utilize this potential energy while ensuring the smoothness and safety of the descent, and how to maintain sufficient independence between different working conditions such as normal descent, emergency descent, and energy recovery, are issues that need to be considered in the design of the boom's hydraulic system.

[0003] Existing electric aerial work platforms often employ power descent or descent based on the boom's own weight during boom luffing and lowering. Taking descent based on weight as an example, the weight of the boom and its supported components acts on the luffing cylinder, causing hydraulic oil to be squeezed out of the rodless chamber. Most of the gravitational potential energy released during boom descent is consumed as heat through throttling, lacking a channel to further convert hydraulic energy into storeable electrical energy. As the number of working cycles increases, this energy loss accumulates, limiting the number of working cycles supported by a unit of battery charge and increasing the thermal load on the hydraulic system.

[0004] Meanwhile, traditional aerial work platforms are typically equipped with an independent emergency power circuit to enable emergency boom descent in case of main power circuit failure. This emergency circuit is used infrequently during normal operation, but it is indispensable to meet the overall safety design requirements of the machine. Therefore, its power components are in a standby state for a long time, resulting in low functional utilization.

[0005] Based on the above, a hydraulic control system is needed that can fully retain the functions of self-weight variable luffing and emergency variable luffing, while adding the function of potential energy recovery. This system should enable the normal descent, emergency descent, and potential energy recovery to form relatively independent oil circuits under the control of switching elements. The system should also switch between emergency drive and energy recovery through the bidirectional working characteristics of the pump motor and the electric generator, so as to reduce throttling losses, improve the overall energy utilization rate of the machine, and take into account fault isolation, safety protection, and oil cleanliness. Summary of the Invention

[0006] The purpose of this invention is to provide a boom luffing hydraulic control system that, while retaining the conventional weight-based and emergency luffing descent functions of the aerial work platform, adds a boom descent potential energy recovery path and uses switching valve groups to ensure that different descent conditions operate according to predetermined oil circuits, thereby improving energy utilization, system redundancy, and operational safety. Another purpose of this invention is to provide an aerial work platform incorporating the aforementioned boom luffing hydraulic control system.

[0007] To solve the above-mentioned technical problems, the present invention provides a boom luffing hydraulic control system, including an oil tank, an oil supply unit, a multi-way valve group, and a luffing cylinder. The oil supply unit is connected to the luffing cylinder through the multi-way valve group. The system also includes a pump motor, an electric generator, a battery unit, and a switching valve group. The battery unit is connected to the electric generator, and the electric generator is connected to the pump motor. The first working port of the pump motor is connected to the oil tank, and the second working port of the pump motor is connected to the multi-way valve group and the luffing cylinder through the switching valve group. In the self-weight luffing mode, the rodless chamber of the luffing cylinder is connected to the oil tank through the switching valve group and the multi-way valve group. In the emergency luffing mode, the second working port of the pump motor is connected to the rod chamber of the luffing cylinder through the switching valve group and the multi-way valve group, and the pump motor operates as a pump, while the electric generator operates as a motor. In the self-weight luffing potential energy recovery mode, the rodless chamber of the luffing cylinder is connected to the second working port of the pump motor through the switching valve group, and the pump motor operates as a motor, while the electric generator operates as a generator.

[0008] Preferably, the multi-way valve group includes a luffing multi-way valve, the switching valve group includes a first switching valve and a second switching valve, the output port of the oil supply unit is connected to the oil inlet of the luffing multi-way valve, the second working port of the pump motor is connected to the first oil port of the first switching valve, the second oil port of the first switching valve is connected to the oil inlet of the luffing multi-way valve, the third oil port of the first switching valve is connected to the first oil port of the second switching valve, the return port of the luffing multi-way valve is connected to the oil tank, the first working port of the luffing multi-way valve is connected to the rodless chamber of the luffing cylinder, and the second working port of the luffing multi-way valve is connected to the... The second oil port of the second switching valve is connected to the rodless chamber and the rod chamber of the luffing cylinder; in the self-weight luffing mode, the third oil port of the second switching valve is connected to the second oil port, and the second working port of the luffing multi-way valve is connected to the return oil port; in the emergency luffing mode, the first oil port of the first switching valve is connected to the second oil port, the inlet of the luffing multi-way valve is connected to the second working port, and the second oil port of the second switching valve is connected to the third oil port; in the self-weight luffing potential energy recovery mode, the third oil port of the second switching valve is connected to the first oil port, and the third oil port of the first switching valve is connected to the first oil port.

[0009] Preferably, a switching valve, a proportional valve, and a descent check valve are sequentially arranged between the rodless chamber of the luffing cylinder and the third oil port of the second switching valve. When oil enters the rodless chamber of the luffing cylinder, the switching valve is closed, and when oil exits the rodless chamber of the luffing cylinder, the switching valve is open.

[0010] Preferably, a balance valve is provided between the first working port of the luffing multi-way valve and the rodless chamber of the luffing cylinder, and an explosion-proof valve is provided between the third oil port of the first switching valve and the first oil port of the second switching valve.

[0011] Preferably, a main oil circuit check valve is provided between the output port of the oil supply unit and the oil inlet of the variable amplitude multi-way valve, an emergency oil circuit check valve is provided between the second oil port of the first switching valve and the oil inlet of the variable amplitude multi-way valve, and a parallel oil inlet check valve and an oil return check valve are provided between the first working port of the pump motor and the oil tank.

[0012] Preferably, the first switching valve and the second switching valve are two-position three-way solenoid directional valves, and the switching valve is a two-position two-way solenoid directional valve; in the self-weight luffing mode, the switching valve and the proportional valve are energized, and the second switching valve is de-energized; in the emergency luffing mode, the switching valve, the first switching valve, and the second switching valve are de-energized; in the self-weight luffing potential energy recovery mode, the switching valve, the proportional valve, the first switching valve, and the second switching valve are energized.

[0013] Preferably, the multi-way valve group further includes a shuttle valve, a compensator, a three-way flow valve, and a main relief valve.

[0014] Preferably, the oil supply unit includes an oil suction filter, a main power motor, an electric proportional displacement pump, and a high-pressure filter, and a return oil filter is provided at the system return oil point.

[0015] Preferably, the battery unit includes a main power battery, an electronic control module, and an emergency battery, wherein the main power battery charges the emergency battery.

[0016] The present invention provides an aerial work platform, including a boom luffing hydraulic control system as described in any one of the above.

[0017] This invention provides a boom luffing hydraulic control system, including an oil tank, an oil supply unit, a multi-way valve group, and a luffing cylinder. The oil supply unit is connected to the luffing cylinder via the multi-way valve group. It also includes a pump motor, an electric generator, a battery unit, and a switching valve group. The battery unit is connected to the electric generator, and the electric generator is connected to the pump motor. The first working port of the pump motor is connected to the oil tank, and the second working port of the pump motor is connected to the multi-way valve group and the luffing cylinder via the switching valve group. In the self-weight luffing mode, the rodless chamber of the luffing cylinder is connected to the oil tank via the switching valve group and the multi-way valve group. In the emergency luffing mode, the second working port of the pump motor is connected to the rod chamber of the luffing cylinder via the switching valve group and the multi-way valve group, and the pump motor operates as a pump, while the electric generator operates as a motor. In the self-weight luffing potential energy recovery mode, the rodless chamber of the luffing cylinder is connected to the second working port of the pump motor via the switching valve group, and the pump motor operates as a motor, while the electric generator operates as a generator.

[0018] The self-weight luffing mode, emergency luffing mode, and self-weight luffing potential energy recovery mode are switched by switching valve groups. In the self-weight luffing potential energy recovery mode, the oil discharged from the rodless chamber of the luffing cylinder drives the pump motor to operate in motor mode, and the pump motor then drives the electric generator to operate in generator mode. This allows at least a portion of the gravitational potential energy released during boom descent to be converted into electrical energy for recovery and storage, thereby reducing the energy consumed entirely by proportional throttling. This enables the pump motor and electric generator to have both energy recovery and emergency power functions, allowing the emergency power components, which are usually used infrequently, to participate in energy recovery during normal operation, thus improving the utilization rate of the equipment.

[0019] The present invention also provides an aerial work platform including the above-mentioned boom luffing hydraulic control system. Since the above-mentioned boom luffing hydraulic control system has the above-mentioned technical effects, the above-mentioned aerial work platform should also have the same technical effects, which will not be described in detail here. Attached Figure Description

[0020] Figure 1 This is a hydraulic schematic diagram of a specific embodiment of the boom luffing hydraulic control system provided by the present invention.

[0021] The components are as follows: 1-oil tank; 2-suction filter; 3-main power motor; 4-electric proportional displacement pump; 5-high pressure filter; 6-first switching valve; 7-emergency oil circuit check valve; 8-main oil circuit check valve; 9-balance valve; 10-luffing cylinder; 11-switching valve; 12-proportional valve; 13-lowering check valve; 14-second switching valve; 15-explosion-proof valve; 16-shuttle valve; 17-luffing multi-way valve; 18-compensator; 19-three-way flow valve; 20-main relief valve; 21-pump motor; 22-return oil filter; 23-return oil check valve; 24-inlet oil check valve; 25-electric generator; 26-main power battery; 27-electronic control module; 28-emergency battery. Detailed Implementation

[0022] The core of this invention is to provide a boom luffing hydraulic control system. While retaining the conventional weight-based and emergency luffing functions of the aerial work platform, it adds a boom descent potential energy recovery path and uses switching valve groups to ensure different descent conditions operate according to predetermined oil circuits, thereby improving energy utilization, system redundancy, and operational safety. Another core aspect of this invention is to provide an aerial work platform incorporating the aforementioned boom luffing hydraulic control system.

[0023] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Please refer to Figure 1 , Figure 1 This is a hydraulic schematic diagram of a specific embodiment of the boom luffing hydraulic control system provided by the present invention.

[0025] This invention provides a boom luffing hydraulic control system, including an oil tank 1, an oil supply unit, a multi-way valve group, and a luffing cylinder 10. The oil supply unit draws hydraulic oil from the oil tank 1 and supplies pressurized oil to the system. The multi-way valve group distributes the pressurized oil according to operational requirements. The luffing cylinder 10 serves as the boom luffing actuator, with the extension or retraction of its piston rod corresponding to the boom's luffing action. In addition to the basic hydraulic circuit described above, the system also includes a pump motor 21, an electric generator 25, a battery unit, and a switching valve group. The battery unit is electrically connected to the electric generator 25, and the electric generator 25 is drive-connected to the pump motor 21, enabling mechanical energy transfer between them. The pump motor 21 has a first working port and a second working port. The first working port is connected to the oil tank 1, and the second working port establishes selective communication with the luffing cylinder 10 through the switching valve group and the multi-way valve group. Thus, the same pump motor 21 and electric generator 25 can serve as a power source when emergency pressurized oil is needed, or as a potential energy recovery actuator when the boom is lowered.

[0026] When the system is in self-weight luffing mode, the gravity of the boom and its load-bearing components drives the luffing cylinder 10 to move, squeezing out the hydraulic oil in the rodless chamber. At this time, the switching valve group selects the conventional self-weight descent path, so that the oil discharged from the rodless chamber of the luffing cylinder 10 enters the multi-way valve group through the switching valve group, and then returns to the oil tank 1 through the return oil channel of the multi-way valve group. This mode does not require the pump motor 21 to bear the driving load, and is suitable for completing conventional self-weight descent when energy recovery is not performed or the conditions for energy recovery are not available. The descent speed can be adjusted by the proportional valve 12 set on the descent branch of the rodless chamber, so that the boom descends at a controlled speed under its own weight.

[0027] When the system is in emergency luffing mode, the electric generator 25 switches to electric motor mode, and the pump motor 21 switches to pump mode. The battery unit provides power to the electric generator 25, which drives the pump motor 21 to rotate. The pump motor 21 draws oil from the oil tank 1 side and outputs pressurized oil from the second working port. The switching valve group connects the second working port of the pump motor 21 to the multi-way valve group and the rod chamber of the luffing cylinder 10, allowing pressurized oil to enter the rod chamber of the luffing cylinder 10 and push the luffing cylinder 10 to move in the direction required for the boom descent; the oil discharged from the rodless chamber of the luffing cylinder 10 returns to the oil tank 1 through the corresponding return oil path. Through this working mode, even if the main oil supply unit cannot output pressurized oil normally, emergency luffing descent can still be completed using the independent power branch composed of the pump motor 21, the electric generator 25, and the battery unit.

[0028] When the system is in the self-weight luffing potential energy recovery mode, the boom's gravity still drives the luffing cylinder 10 to move. However, the switching valve group no longer allows the rodless chamber to return oil mainly through the multi-way valve group. Instead, it connects the rodless chamber of the luffing cylinder 10 to the second working port of the pump motor 21. The pressurized oil discharged from the rodless chamber acts on the pump motor 21, putting it into motor mode and outputting mechanical torque. The pump motor 21 drives the electric generator 25 to rotate, and the electric generator 25 switches to generator mode and generates electrical energy, which is received and stored through the battery unit. At this time, the first working port of the pump motor 21 is connected to the oil tank 1, allowing the oil passing through the pump motor 21 to return to the oil tank 1. This mode converts at least a portion of the hydraulic energy that would otherwise be consumed through the throttling element into electrical energy, realizing the recovery and utilization of the gravitational potential energy of the boom during descent.

[0029] Based on the aforementioned hydraulic system, the switching valve group may specifically include a first switching valve 6 and a second switching valve 14, and the multi-way valve group includes a luffing multi-way valve 17. The output port of the oil supply unit is connected to the inlet port of the luffing multi-way valve 17, the return port of the luffing multi-way valve 17 is connected to the oil tank 1, the first working port of the luffing multi-way valve 17 is connected to the rodless chamber of the luffing cylinder 10, and the second working port is connected to the second port of the second switching valve 14. The second working port of the pump motor 21 is connected to the first port of the first switching valve 6, the second port of the first switching valve 6 is connected to the inlet port of the luffing multi-way valve 17, and the third port of the first switching valve 6 is connected to the first port of the second switching valve 14. The third port of the second switching valve 14 is connected to both the rodless chamber and the rod chamber of the luffing cylinder 10. Through the aforementioned port connections, the first switching valve 6 is used to select the connection relationship between the pump motor 21 and the oil inlet side or potential energy recovery branch of the luffing multi-way valve 17, and the second switching valve 14 is used to select the connection relationship between the descent oil discharge of the luffing cylinder 10 and the return oil path or potential energy recovery path of the multi-way valve group.

[0030] Specifically, during gravity-based luffing descent, the second switching valve 14 is positioned to connect the third oil port to the second oil port, and the luffing multi-way valve 17 is in operation, connecting the second working port to the return oil port. Oil discharged from the rodless chamber of the luffing cylinder 10 under the weight of the boom enters the third oil port of the second switching valve 14, then flows from the second oil port into the second working port of the luffing multi-way valve 17, and finally flows from the return oil port of the luffing multi-way valve 17 to the oil tank 1. This oil circuit constitutes the conventional gravity-based descent channel. Because this channel returns oil via the luffing multi-way valve 17, the original multi-way valve control mode can be retained when potential energy recovery is not activated, allowing the system to maintain basic descent capability even when energy recovery conditions are not met.

[0031] During emergency luffing descent, the first switching valve 6 is positioned to connect the first and second oil ports, the luffing multi-way valve 17 is positioned to connect the inlet and the second working port, and the second switching valve 14 is positioned to connect the second and third oil ports. After the pump motor 21 operates in pump mode, the pressurized oil output from its second working port first enters the first oil port of the first switching valve 6, and is then sent from the second oil port to the inlet side of the luffing multi-way valve 17. The pressurized oil then enters the rod chamber of the luffing cylinder 10 via the inlet and second working port of the luffing multi-way valve 17, and the second and third oil ports of the second switching valve 14. Under the pressure of the rod chamber, the luffing cylinder 10 retracts, corresponding to the emergency descent of the boom. Simultaneously with this oil intake process, the oil in the rodless chamber can return to the oil tank 1 via the balance valve 9 and the luffing multi-way valve 17. The above path is provided by an independent pressurized oil source from the pump motor 21, so that the emergency action does not depend on the normal operation of the oil supply unit.

[0032] Specifically, during potential energy recovery under luffing conditions, the second switching valve 14 is positioned to connect the third oil port to the first oil port, and the first switching valve 6 is positioned to connect the third oil port to the first oil port. Oil discharged from the rodless chamber of the luffing cylinder 10 enters the third oil port of the second switching valve 14, then flows from the first oil port to the third oil port of the first switching valve 6, and finally reaches the second working port of the pump motor 21 via the first oil port of the first switching valve 6. The pressurized oil drives the pump motor 21 to rotate in motor mode, and then returns to the oil tank 1 via the first working port of the pump motor 21. The mechanical energy output by the pump motor 21 is transmitted to the electric generator 25, putting it into generator mode. Through the linkage of the first switching valve 6 and the second switching valve 14, the potential energy recovery oil circuit bypasses the conventional return oil path of the luffing multi-way valve 17, thus forming a dedicated energy recovery channel while maintaining the availability of the normal weight descent path.

[0033] Based on the aforementioned oil circuit connections, a switching valve 11, a proportional valve 12, and a descent check valve 13 are sequentially installed on the descent branch between the rodless chamber of the luffing cylinder 10 and the third port of the second switching valve 14. This descent branch is distinct from the main working branch connected to the first working port of the luffing multi-way valve 17 via the balance valve 9, allowing the oil inlet and outlet of the rodless chamber of the luffing cylinder 10 to be controlled via different paths. When the rodless chamber of the luffing cylinder 10 needs oil inlet, the switching valve 11 remains closed, thereby preventing pressure oil from flowing backward through the descent branch; the oil inlet to the rodless chamber is mainly completed through the working oil circuit where the first working port of the luffing multi-way valve 17 and the balance valve 9 are located. When the boom descends under its own weight and the rodless chamber needs oil outlet, the switching valve 11 opens, allowing the oil in the rodless chamber to enter the controlled descent channel where the proportional valve 12 and the descent check valve 13 are located.

[0034] The proportional valve 12 is located after the switching valve 11 and is used to continuously or stepwise regulate the discharge flow rate of the rodless chamber. Changes in boom posture will cause changes in the load on the luffing cylinder 10. If only a fixed throttle orifice is used, the descent speed is prone to change with the load. By adjusting the opening of the proportional valve 12, the flow rate entering the subsequent second switching valve 14 can be matched with the target descent speed. The descent check valve 13 is used to restrict the reverse flow in this branch, so that the oil after the proportional valve 12 flows to the second switching valve 14 in a predetermined direction. The switching valve 11 and the proportional valve 12 are connected in series. On the one hand, the proportional valve 12 can undertake the speed regulation function, and on the other hand, the switching valve 11 can provide independent on / off control, thus forming an additional cut-off link when it is necessary to stop descent.

[0035] Furthermore, a balance valve 9 is installed between the first working port of the luffing multi-way valve 17 and the rodless chamber of the luffing cylinder 10. The balance valve 9 is located on the main working oil circuit of the rodless chamber, which bears the load of the boom. It controls the oil flow during normal luffing operations and load holding to prevent the cylinder from losing necessary back pressure and support under load. When the boom performs emergency luffing descent, the oil return from the rodless chamber can enter the luffing multi-way valve 17 via the balance valve 9, and then return to the oil tank 1 via the return oil channel. The balance valve 9 coexists with the independent descent branch of the rodless chamber, enabling the system to achieve load control of the conventional working oil circuit using both the multi-way valve and the balance valve, and also to form a dedicated descent control path using components such as the switching valve 11 and the proportional valve 12 during gravity descent or potential energy recovery.

[0036] An explosion-proof valve 15 is installed between the third port of the first switching valve 6 and the first port of the second switching valve 14. This location is in the potential energy recovery channel, connecting the descent discharge side of the luffing cylinder 10 to the pump motor 21 side. When an abnormal rupture or sudden flow change occurs in the relevant pipeline, the explosion-proof valve 15 can restrict or shut off the branch, reducing the risk of abnormal boom descent caused by rapid release of hydraulic oil on the load side. The explosion-proof valve 15, proportional valve 12, and switching valve 11 are located at different control levels. The explosion-proof valve 15 provides protection based on the hydraulic state, the proportional valve 12 performs electronic speed regulation and shut-off functions, and the switching valve 11 provides independent on / off control in series. The three valves work together to ensure that the potential energy recovery branch retains necessary safety control capabilities while achieving energy utilization.

[0037] Furthermore, a main oil circuit check valve 8 is installed between the output port of the oil supply unit and the inlet of the luffing multi-way valve 17. The main oil circuit check valve 8 allows pressurized oil output from the main oil supply unit to enter the luffing multi-way valve 17, while simultaneously restricting the reverse flow of oil from the inlet side of the luffing multi-way valve 17 into the main oil supply unit. An emergency oil circuit check valve 7 is installed between the second port of the first switching valve 6 and the inlet of the luffing multi-way valve 17. The emergency oil circuit check valve 7 allows pressurized oil output from the pump motor 21 under emergency pump conditions to enter the luffing multi-way valve 17, while restricting reverse flow. The main oil circuit check valve 8 and the emergency oil circuit check valve 7 ensure that the main oil supply path and the emergency oil supply path are each subject to unidirectional constraints before converging into the inlet side of the luffing multi-way valve 17, reducing the possibility of backflow between the two pressure sources.

[0038] A parallel inlet check valve 24 and a return check valve 23 are installed between the first working port of the pump motor 21 and the oil tank 1. When the pump motor 21 is in pump mode, it needs to obtain suction oil from the oil tank 1 side. The inlet check valve 24 establishes a suitable one-way passage for the pump motor 21 in the suction direction. When the pump motor 21 is in motor mode, the oil passing through the pump motor 21 needs to be discharged back to the oil tank 1. The return check valve 23 establishes a passage for the corresponding return direction. The two check valves are connected in parallel, but their opening directions match the corresponding operating conditions. This ensures that when the pump motor 21 switches between pump mode and motor mode, the first working port can form the required oil exchange with the oil tank 1, while limiting the backflow of oil that does not conform to the predetermined direction. This structure also helps to isolate the potential energy recovery return oil from the main pump suction side, reducing the risk that the descending return oil carrying contaminants will enter the main suction oil circuit in reverse.

[0039] Regarding valve types, the first switching valve 6 and the second switching valve 14 can be two-position three-way solenoid directional valves, and the switching valve 11 can be a two-position two-way solenoid directional valve. With electromagnetic control, the on / off and switching of each valve can be uniformly controlled according to the currently selected descent condition of the entire machine. In the self-weight luffing mode, the switching valve 11 and the proportional valve 12 are energized, opening the rodless chamber descent branch and allowing the proportional valve 12 to regulate the flow. The second switching valve 14 is de-energized, maintaining the connection between the third and second oil ports, thereby guiding the descent oil to the return path of the luffing multi-way valve 17. At this time, the first switching valve 6 does not need to establish a connection between the pump motor 21 and the recovery branch, and the system operates in the conventional self-weight descent mode.

[0040] In the emergency luffing mode, the switching valve 11, the first switching valve 6, and the second switching valve 14 are all de-energized. The first switching valve 6, in its de-energized position, connects the first oil port to the second oil port, and the second switching valve 14, in its de-energized position, connects the second oil port to the third oil port. Therefore, the pressure oil output from the second working port of the pump motor 21 can sequentially enter the rod chamber of the luffing cylinder 10 via the first switching valve 6, the emergency oil circuit check valve 7, the luffing multi-way valve 17, and the second switching valve 14. After the switching valve 11 is de-energized, the independent descent branch of the rodless chamber is closed, and the return oil from the rodless chamber is completed by the circuit containing the balance valve 9 and the luffing multi-way valve 17. By setting the key reversing state under emergency luffing to the de-energized position of the corresponding solenoid valve, this operating condition can still maintain a clear hydraulic connection even when the main control or partial power supply conditions are abnormal.

[0041] In the gravity-controlled potential energy recovery mode, the switching valve 11, proportional valve 12, first switching valve 6, and second switching valve 14 are all energized. Switching valve 11 opens, proportional valve 12 establishes a corresponding throttling opening according to the descent speed requirement, second switching valve 14 switches to connect the third port to the first port, and first switching valve 6 switches to connect the third port to the first port, thereby guiding the rodless chamber descent oil to the second working port of pump motor 21. Pump motor 21 operates in motor mode and drives electric generator 25 to generate electricity. Through the combination of energization and de-energization under different operating conditions, first switching valve 6 and second switching valve 14 establish a clear state correspondence between the three main oil circuits, enabling switching between normal gravity descent, emergency descent, and potential energy recovery according to control commands.

[0042] The multi-way valve assembly may also include a shuttle valve 16, a compensator 18, a three-way flow valve 19, and a main relief valve 20. The shuttle valve 16 selects a pressure signal from relevant pressure signals that reflects the load demand. The compensator 18 is located in the relevant flow control loop of the amplitude-changing multi-way valve 17 to compensate for the pressure difference across the valve port when the load pressure changes, thus reducing the impact of load changes on the flow rate through the amplitude-changing multi-way valve 17. The three-way flow valve 19 distributes or bypasses the flow rate entering the multi-way valve assembly. The main relief valve 20 limits the maximum pressure in the main oil circuit of the multi-way valve assembly. When the load pressure reaches the set protection level, the main relief valve 20 can limit the system pressure from continuing to rise by overflowing. The shuttle valve 16, compensator 18, three-way flow valve 19, and main relief valve 20 work in conjunction with the amplitude-changing multi-way valve 17 to maintain the required flow and pressure control characteristics for the amplitude-changing operation under main oil supply conditions, and to provide existing downstream control conditions for the pressure oil after the emergency oil circuit is connected to the multi-way valve assembly.

[0043] The oil supply unit may include a suction filter 2, a main drive motor 3, an electro-proportional displacement pump 4, and a high-pressure filter 5. The main drive motor 3 is connected to the electro-proportional displacement pump 4. During normal operation, the main drive motor 3 drives the electro-proportional displacement pump 4 to rotate. The electro-proportional displacement pump 4 draws hydraulic oil from the oil tank 1 through the suction filter 2 and outputs clean pressurized oil through the high-pressure filter 5. The suction filter 2 is used to intercept large particulate contaminants entering the pump from the oil tank side, and the high-pressure filter 5 is used to further control contamination before the pressurized oil enters the precision valve components. The displacement of the electro-proportional displacement pump 4 can be adjusted according to the overall machine control requirements, so that the oil supply flow under normal main drive conditions can match the boom movement requirements. A return oil filter 22 is installed at the system return oil point. Oil from the multi-way valve group and other return oil branches passes through the return oil filter 22 before returning to the oil tank 1, intercepting contaminants in the hydraulic oil from the return oil side. Through the filtration configuration at the suction, high-pressure, and return oil points, a contamination control link covering the main oil circulation path can be formed.

[0044] Based on the boom luffing hydraulic control system provided in the above-described specific embodiments, the battery unit may include a main power battery 26, an electronic control module 27, and an emergency battery 28. The main power battery 26, as the main energy storage unit of the entire machine, can provide electrical energy to the main power system and receive and store recovered electrical energy; the main power battery 26 can also charge the emergency battery 28, ensuring that the emergency battery 28 maintains sufficient power for emergency operations under normal conditions. The electronic control module 27 is located between the electric generator 25 and the battery, and is used to adapt the electrical energy transfer of the electric generator 25 in both motor mode and generator mode. When the system enters the emergency luffing mode, the emergency power supply side can supply power to the electric generator 25 to drive the pump motor 21; when the system enters the potential energy recovery mode, the electrical energy generated by the electric generator 25 is converted by the electronic control module 27 and then sent to the main power battery 26 for storage. In this way, the same electric pump motor assembly can achieve bidirectional conversion between electrical energy and hydraulic energy under different operating conditions.

[0045] In addition to the above-described implementation methods corresponding to each layer of the structure, the first stage of the two-stage potential energy recovery involves the boom pushing the luffing cylinder 10 under its own weight. This causes the oil in the rodless chamber to flow out through the switching valve 11, proportional valve 12, and descent check valve 13. A portion of this oil can then be directly replenished into the rod chamber of the luffing cylinder 10, utilizing the flow rate discharged from the rodless chamber to meet the flow requirements of the rod chamber. This regeneration path reduces the amount of oil that needs to be directly returned to the oil tank and maintains a certain level of oil replenishment in the rod chamber. This regeneration circuit also helps to mitigate boom vibration caused by insufficient back pressure in the rod chamber during luffing operations and facilitates a faster response to emergency luffing descent maneuvers.

[0046] The second stage of the two-stage potential energy recovery is the recovery of excess hydraulic flow through hydraulic power generation. When the boom descends under its own weight and energy recovery conditions are met, the oil discharged from the rodless chamber, which still needs to be discharged after regeneration, can be sent to the pump motor 21 via the second switching valve 14, the explosion-proof valve 15, and the first switching valve 6. The pump motor 21 operates in motor mode under the drive of this oil and drives the electric generator 25 to generate electricity. The electrical energy is then sent to the main power battery 26 for storage via the electronic control module 27. Therefore, the two-stage recovery does not simply send all the flow from the rodless chamber directly into the power generation branch, but first utilizes the flow that can be regenerated between the two chambers of the cylinder, and then converts the remaining usable hydraulic energy into electrical energy, thus taking into account both hydraulic regeneration and electrical energy recovery.

[0047] It also includes a battery status detector. When the boom is preparing to descend under its own weight, the control program detects the status and charge of the main power battery 26. When the main power battery 26 is in a suitable state and not fully charged, and has the conditions to continue receiving and recovering electrical energy, the switching valve 11, proportional valve 12, second switching valve 14, and first switching valve 6 operate according to the corresponding states of the potential energy recovery mode, guiding the descent hydraulic pump motor 21 to generate electricity. When it is detected that the main power battery 26 is not suitable to continue receiving and recovering electrical energy or is fully charged, the potential energy recovery path is not established, and the normal self-weight luffing descent hydraulic circuit is switched back, so that the boom can still descend safely under its own weight. Thus, the energy recovery function is an additional function activated when the energy storage conditions are met, without sacrificing the basic descent capability.

[0048] In the potential energy recovery mode, the reaction torque generated when the pump motor 21 drives the electric generator 25 to generate electricity forms a load on the descending hydraulic flow. The proportional valve 12 can still serve as the main descending flow regulation element, while the energy conversion load of the pump motor 21 and the electric generator 25 can participate in the descending process as additional resistance. When the two work together, the sudden changes in descending speed caused by boom angle changes and load changes can be reduced, and the impact during start-up and shutdown can be reduced.

[0049] The electric generator 25 can be a permanent magnet AC motor capable of switching between electric motor mode and generator mode, while the pump motor 21 uses a hydraulic component capable of switching between pump mode and motor mode. The main power battery 26 not only supplies power for the main operation of the vehicle, but also recovers electrical energy and replenishes the emergency battery 28, thus forming a synergy between energy storage and emergency protection.

[0050] The type and connection method of each valve can also be adjusted according to the situation, all of which are within the protection scope of this invention.

[0051] In addition to the boom luffing hydraulic control system described above, a specific embodiment of the present invention also provides an aerial work platform including the boom luffing hydraulic control system described above. The structure of other parts of the aerial work platform can be found in the prior art, and will not be described in detail here.

[0052] The boom luffing hydraulic control system and aerial work platform provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A boom luffing hydraulic control system, comprising an oil tank (1), an oil supply unit, a multi-way valve group, and a luffing cylinder (10), wherein the oil supply unit is connected to the luffing cylinder (10) through the multi-way valve group, characterized in that, It also includes a pump motor (21), an electric generator (25), a battery unit, and a switching valve group. The battery unit is connected to the electric generator (25), and the electric generator (25) is connected to the pump motor (21). The first working port of the pump motor (21) is connected to the oil tank (1), and the second working port of the pump motor (21) is connected to the multi-way valve group and the luffing cylinder (10) through the switching valve group. In the self-weight luffing mode, the rodless chamber of the luffing cylinder (10) is connected to the multi-way valve group through the switching valve group. The oil tank (1); in the emergency luffing mode, the second working port of the pump motor (21) is connected to the rod chamber of the luffing cylinder (10) through the switching valve group and the multi-way valve group, and the pump motor (21) is in pump mode, and the electric generator (25) is in motor mode; in the self-weight luffing potential energy recovery mode, the rodless chamber of the luffing cylinder (10) is connected to the second working port of the pump motor (21) through the switching valve group, and the pump motor (21) is in motor mode, and the electric generator (25) is in generator mode.

2. The boom luffing hydraulic control system according to claim 1, characterized in that, The multi-way valve group includes a variable amplitude multi-way valve (17), and the switching valve group includes a first switching valve (6) and a second switching valve (14). The output port of the oil supply unit is connected to the oil inlet of the variable amplitude multi-way valve (17). The second working port of the pump motor (21) is connected to the first oil port of the first switching valve (6). The second oil port of the first switching valve (6) is connected to the oil inlet of the variable amplitude multi-way valve (17). The third oil port of the first switching valve (6) is connected to the first oil port of the second switching valve (14). The return port of the variable amplitude multi-way valve (17) is connected to the oil tank (1). The first working port of the variable amplitude multi-way valve (17) is connected to the rodless chamber of the variable amplitude cylinder (10). The second working port of the variable amplitude multi-way valve (17) is connected to the first oil port of the second switching valve (14). The working port is connected to the second oil port of the second switching valve (14), and the third oil port of the second switching valve (14) is connected to the rodless chamber and the rod chamber of the luffing cylinder (10); in the self-weight luffing mode, the third oil port of the second switching valve (14) is connected to the second oil port, and the second working port of the luffing multi-way valve (17) is connected to the return oil port; in the emergency luffing mode, the first oil port of the first switching valve (6) is connected to the second oil port, the inlet of the luffing multi-way valve (17) is connected to the second working port, and the second oil port of the second switching valve (14) is connected to the third oil port; in the self-weight luffing potential energy recovery mode, the third oil port of the second switching valve (14) is connected to the first oil port, and the third oil port of the first switching valve (6) is connected to the first oil port.

3. The boom luffing hydraulic control system according to claim 2, characterized in that, A switching valve (11), a proportional valve (12), and a descent check valve (13) are sequentially arranged between the rodless chamber of the luffing cylinder (10) and the third oil port of the second switching valve (14). When oil enters the rodless chamber of the luffing cylinder (10), the switching valve (11) is closed, and when oil exits the rodless chamber of the luffing cylinder (10), the switching valve (11) is opened.

4. The boom luffing hydraulic control system according to claim 3, characterized in that, A balance valve (9) is provided between the first working port of the luffing multi-way valve (17) and the rodless chamber of the luffing cylinder (10), and an explosion-proof valve (15) is provided between the third oil port of the first switching valve (6) and the first oil port of the second switching valve (14).

5. The boom luffing hydraulic control system according to claim 4, characterized in that, A main oil circuit check valve (8) is provided between the output port of the oil supply unit and the inlet port of the variable amplitude multi-way valve (17). An emergency oil circuit check valve (7) is provided between the second oil port of the first switching valve (6) and the inlet port of the variable amplitude multi-way valve (17). A parallel inlet check valve (24) and a return check valve (23) are provided between the first working port of the pump motor (21) and the oil tank (1).

6. The boom luffing hydraulic control system according to claim 5, characterized in that, The first switching valve (6) and the second switching valve (14) are two-position three-way solenoid directional valves, and the switching valve (11) is a two-position two-way solenoid directional valve. In the self-weight variable amplitude mode, the switching valve (11) and the proportional valve (12) are energized, and the second switching valve (14) is de-energized. In the emergency variable amplitude mode, the switching valve (11), the first switching valve (6) and the second switching valve (14) are de-energized. In the self-weight variable amplitude potential energy recovery mode, the switching valve (11), the proportional valve (12), the first switching valve (6) and the second switching valve (14) are energized.

7. The boom luffing hydraulic control system according to claim 1, characterized in that, The multi-way valve group also includes a shuttle valve (16), a compensator (18), a three-way flow valve (19), and a main relief valve (20).

8. The boom luffing hydraulic control system according to claim 1, characterized in that, The oil supply unit includes an oil suction filter (2), a main power motor (3), an electric proportional displacement pump (4), and a high pressure filter (5). A return oil filter (22) is provided at the system return oil point.

9. The boom luffing hydraulic control system according to any one of claims 1 to 8, characterized in that, The battery unit includes a main power battery (26), an electronic control module (27), and an emergency battery (28), wherein the main power battery (26) charges the emergency battery (28).

10. An aerial work platform, characterized in that, Includes the boom luffing hydraulic control system as described in any one of claims 1 to 9.

Images