Hydraulic system with energy recovery function and aerial work platform

Abstract

The utility model discloses a hydraulic system and aerial work platform with energy recovery function, the system includes oil tank, pump motor, first overflow valve, second overflow valve, first throttling element, first reversing valve, second reversing valve, third reversing valve, fourth reversing valve, steering oil cylinder, first lifting oil cylinder, second lifting oil cylinder, drive module, control module and energy storage element, the oil outlet of pump motor is connected with first reversing valve, first overflow valve, first reversing valve is connected with second reversing valve, and second reversing valve is connected with steering oil cylinder, first reversing valve is connected with third reversing valve, fourth reversing valve, and third reversing valve, fourth reversing valve is connected with first lifting oil cylinder, second lifting oil cylinder respectively, the utility model discloses cancel the one -way throttle valve on the pipeline where third reversing valve and fourth reversing valve are, has improved energy recovery efficiency, has added hydraulic steering loop and optimized hydraulic principle, has reduced the whole machine purchase and maintenance cost.

Description

Technical Field

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

[0002] With the continuous iteration and upgrading of scissor lifts (hereinafter referred to as scissors), the main technologies have become increasingly mature. In recent years, the electrification trend of scissor lift systems has accelerated significantly, and OEMs have begun to increase their research and development of energy-saving technologies.

[0003] Patent document CN117419077A discloses an energy control method and system for a lifting vehicle. In its hydraulic system, a one-way valve y4 and a throttle valve y6 are used to control the descent speed. When energy is recovered during descent, coils SV1, SV2, SV3 and SV4 are energized. The oil in the rodless chambers of lifting cylinders b1 and b2 flows through the reversing valve y5, the throttle valve y6 and the emergency valve y3 through the hydraulic component y1, and finally flows back to the oil tank y2. At this time, the hydraulic component y1 reverses and drives the motor to generate electricity, thereby realizing energy recovery.

[0004] While this energy control method can achieve potential energy recovery, it still has the following unresolved drawbacks:

[0005] (1) When the platform descends, the oil in the rodless chamber of the lifting cylinder must pass through the throttle valve y6 to flow back to the oil tank. In order to ensure that the platform will not descend rapidly after the pipeline breaks, the throttle valve y6 is often set with a relatively small throttle orifice. The oil will consume more energy when flowing through the relatively small throttle orifice, resulting in low energy recovery efficiency during descent.

[0006] (2) Throttling valve y6 is a fixed throttling orifice. When the load on the platform is large, the pressure difference between the two ends of throttling valve y6 is large, the flow rate of the oil is large, the descent speed is fast, and more energy is used to recover. However, when the load on the platform is small, the pressure difference between the two ends of throttling valve y6 is small, the flow rate of the oil is small, the descent speed is slow, less energy is used to recover, and the energy recovery efficiency is not high.

[0007] (3) It is not clearly stated what specific component the hydraulic component y1 is. Judging from the symbols in the attached figure, the hydraulic component y1 is a two-way pump. Theoretically, a two-way pump cannot realize the function of a hydraulic motor. When the platform descends to recover energy, the potential energy is converted into hydraulic energy. The hydraulic energy needs to be converted into kinetic energy through the hydraulic motor in order to drive the motor to reverse and generate electricity. Obviously, the hydraulic component y1 cannot realize this function.

[0008] (4) If the existing hydraulic system does not include a steering circuit, it indicates that it uses electric cylinder steering. The steering of the electric drive platform includes two schemes: electric cylinder steering and hydraulic cylinder steering. Electric cylinder steering is highly efficient, but the procurement and maintenance costs are also very high, and the application scenarios are limited. Hydraulic cylinder steering is mature and reliable, and the procurement and maintenance costs are very low. Although the efficiency is lower than that of electric cylinder steering, the steering action accounts for a very small proportion in the entire use scenario of the scissor lift, so the energy saved is also very small, and the impact on the range is negligible. Considering all factors, the cost performance is not high. Utility Model Content

[0009] The purpose of this utility model is to provide a hydraulic system and aerial work platform with energy recovery function to solve the problems of low energy recovery efficiency, high procurement and maintenance costs of electric cylinder steering, and limited application scenarios in the existing technology.

[0010] This utility model solves the above-mentioned technical problems through the following technical solution: a hydraulic system with energy recovery function, including an oil tank, a pump motor, a first relief valve, a second relief valve, a first throttling element, a first reversing valve, a second reversing valve, a third reversing valve, a fourth reversing valve, a steering cylinder, a first lifting cylinder, a second lifting cylinder, a drive module, a control module, and an energy storage element; the pump motor is driven by the drive module, the drive module is electrically connected to the control module and the energy storage element, and the control module is electrically connected to the electromagnets of the first reversing valve, the second reversing valve, the third reversing valve, and the fourth reversing valve;

[0011] The oil inlet of the pump motor is connected to the oil tank, and the oil outlet of the pump motor is connected to the third port of the first reversing valve and the oil inlet of the first overflow valve; the second port of the first reversing valve is connected to the third port of the second reversing valve, the second port and the fourth port of the second reversing valve are respectively connected to the A port and the B port of the steering cylinder, the first port of the second reversing valve is connected to the second end of the first throttling element, the oil outlet of the first overflow valve and the oil tank; the first end of the first throttling element is connected to the first port of the first reversing valve.

[0012] The fourth port of the first reversing valve is connected to the first port of the third reversing valve and the first port of the fourth reversing valve. The second port of the third reversing valve is connected to the A port of the first lifting cylinder, and the second port of the fourth reversing valve is connected to the A port of the second lifting cylinder. The second port of the third reversing valve is connected to the first port of the third reversing valve through the second relief valve. The B ports of the first lifting cylinder and the second lifting cylinder are connected to the atmosphere or the oil tank.

[0013] During the lifting operation, the control module controls the motor in the drive module to rotate forward, driving the pump motor to rotate. At this time, the pump motor is used as a pump. The oil output by the pump motor is divided into two paths after passing through the third and fourth ports of the first reversing valve: one path enters port A of the first lifting cylinder through the third reversing valve, and the other path enters port A of the second lifting cylinder through the fourth reversing valve. The piston rods of the first and second lifting cylinders extend to realize the lifting action.

[0014] During the energy recovery descent operation, the oil in the rodless chamber of the first lifting cylinder flows out through the third directional valve, and the oil in the rodless chamber of the second lifting cylinder flows out through the fourth directional valve. After merging, the oil flows into the pump motor through the fourth and third ports of the first directional valve. At this time, the pump motor functions as a hydraulic motor. The pump motor drives the motor in the drive module to reverse and generate a reverse electromotive force. The reverse electromotive force is rectified by the driver in the drive module to output DC power, which charges the energy storage element and realizes energy recovery. The oil flowing out of the pump motor flows into the oil tank, realizing the descent action.

[0015] When descending without energy recovery, the oil in the rodless chamber of the first lifting cylinder flows out through the third directional valve, and the oil in the rodless chamber of the second lifting cylinder flows out through the fourth directional valve. After the two merge, they flow back to the oil tank through the fourth port and the first port of the first directional valve and the first throttling element, thus realizing the descent action.

[0016] In the left-turn mode, the control module controls the motor in the drive module to rotate forward, driving the pump motor to rotate. At this time, the pump motor functions as a pump. The oil output by the pump motor flows into port B of the steering cylinder through the third and second ports of the first reversing valve, and the third and fourth ports of the second reversing valve, pushing the piston rod to move to the left, thereby driving the steering mechanism to achieve the left-turn function. In the right-turn mode, the control module controls the motor in the drive module to rotate forward, driving the pump motor to rotate. At this time, the pump motor functions as a pump. The oil output by the pump motor flows into port A of the steering cylinder through the third and second ports of the first reversing valve, and the third and second ports of the second reversing valve, pushing the piston rod to move to the right, thereby driving the steering mechanism to achieve the right-turn function.

[0017] The hydraulic system of this invention eliminates the one-way throttle valves on the pipelines containing the third and fourth directional valves, avoiding energy loss caused by the oil flowing through the one-way throttle valves during the energy recovery process, thus increasing the recovered energy and improving energy recovery efficiency. This invention also adds a hydraulic steering circuit and optimizes the hydraulic principle, making the hydraulic steering circuit simple and reliable. Compared with the electric cylinder steering solution, this invention significantly reduces the overall procurement and maintenance costs, resulting in a higher overall cost-performance ratio and a wider range of applications.

[0018] Furthermore, a first check valve is connected in parallel to both ends of the pump motor.

[0019] The first check valve, acting as a bypass oil replenishment check valve, can replenish oil when the pump motor is used as a hydraulic motor and experiences cavitation or poor oil suction, preventing insufficient lubrication of the pump motor due to lack of oil, which would affect its service life.

[0020] Furthermore, a second throttling element is provided between port A of the steering cylinder and the second port of the second directional valve, and a third throttling element is provided between port B of the steering cylinder and the fourth port of the second directional valve.

[0021] The second and third throttling elements are used to provide a certain back pressure, thereby stabilizing oil fluctuations and making steering smoother.

[0022] Furthermore, the third port of the second directional valve is connected to the first port of the second directional valve through a third relief valve.

[0023] When the pressure in the circuit where the third port of the second directional valve is located exceeds the set value of the third relief valve, the third relief valve opens and directly releases the high-pressure oil to the oil tank to prevent the system from being damaged by excessive pressure. When the second directional valve is switching, the third relief valve can provide a temporary pressure relief path for the third port of the second directional valve to avoid pressure shock and protect the pipeline and components.

[0024] Furthermore, a second check valve and a third check valve are provided in parallel on the pipeline connected to the fourth port of the first reversing valve.

[0025] The parallel second and third check valves can not only achieve normal lifting operations, but also ensure that there is oil between the second and third check valves and the third and fourth directional valves. In this way, during the descent, the back pressure can be quickly established at the first port of the third and fourth directional valves at the moment of switching, avoiding the jerking sensation caused by the initial fast speed followed by slow speed during descent.

[0026] Furthermore, a first safety valve is provided at the first port of the third directional valve, and a second safety valve is provided at the first port of the fourth directional valve.

[0027] Under normal descent conditions, the first and second safety valves are always open. The energy consumed by the oil flowing through the first and second safety valves is much less than the energy lost by the throttle valve. Therefore, compared with the existing system, the recoverable energy is increased and the energy recovery efficiency is improved. The first and second safety valves can prevent rapid descent caused by pipeline rupture or motor stall during descent, thus improving safety.

[0028] Furthermore, the first directional valve is an electro-proportional directional valve, and the system also includes a first sensor and a second sensor electrically connected to the control module; the first sensor is used to detect the platform load weight, the second sensor is used to detect the ambient temperature inside the control module, and the control module is used to adjust the opening of the first directional valve according to the platform load weight detected by the first sensor and the ambient temperature detected by the second sensor, so as to increase the energy recovery efficiency or prevent the voltage or current of energy recovery from exceeding the allowable value of the energy storage element.

[0029] Furthermore, the first sensor is connected via a pipe between the A port of the second lifting cylinder and the second port of the fourth directional valve through a fourth throttling element.

[0030] The fourth throttling element stabilizes oil fluctuations, thereby reducing pressure fluctuations and making the detection results of the first sensor more stable.

[0031] Furthermore, the second, third, and fourth directional control valves are all solenoid directional control valves; or, the second directional control valve is a solenoid directional control valve, and the third and fourth directional control valves are both electro-proportional directional control valves.

[0032] Furthermore, a first filter is provided on the oil outlet pipe of the oil tank, and a second filter is provided on the oil return pipe of the oil tank. The oil tank, the B port of the first lifting cylinder, and the B port of the second lifting cylinder are connected to an air filter.

[0033] Furthermore, the pump motor is a unidirectional pump motor or a bidirectional pump motor.

[0034] Based on the same concept, this utility model also provides an aerial work platform, which includes a hydraulic system with energy recovery function as described above.

[0035] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0036] This invention improves the original hydraulic system by eliminating the one-way throttle valves on the pipelines containing the third and fourth directional valves. This avoids the energy loss caused by the oil flowing through the one-way throttle valves during the energy recovery process in the descent zone, thus increasing the recovered energy and improving the energy recovery efficiency. This invention also adds a hydraulic steering circuit and optimizes the hydraulic principle. The hydraulic steering circuit is simple and reliable. Compared with the electric cylinder steering solution, this invention significantly reduces the overall machine procurement and maintenance costs, resulting in a higher overall cost-performance ratio and a wider range of applications. Attached Figure Description

[0037] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of a hydraulic system with energy recovery function in an embodiment of this utility model;

[0039] Figure 2 This is a schematic diagram of the hydraulic system under the lifting condition in this embodiment of the utility model;

[0040] Figure 3 This is a schematic diagram of the hydraulic system under the energy recovery condition during descent in this embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram of the hydraulic system in the descent condition without energy recovery, as described in this utility model embodiment.

[0042] Figure 5 This is a schematic diagram of the hydraulic system under the left-turn condition in an embodiment of this utility model.

[0043] Explanation of reference numerals in the attached diagram: 1-Fuel tank, 2-First filter, 3-Second filter, 4-Air filter, 5-First safety valve, 6-Third directional valve, 7-Second relief valve, 8-First lifting cylinder, 9-Second lifting cylinder, 10-Fourth throttling element, 11-First sensor, 12-Fourth directional valve, 13-Second safety valve, 14-Steering cylinder, 15-Second throttling element, 16-Third throttling element, 17-Second directional valve, 18-Third relief valve, 19-First directional valve, 20-First check valve, 21-First throttling element, 22-First relief valve, 23-Motor, 24-Pump motor, 25-Third check valve, 26-Second check valve. Detailed Implementation

[0044] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0045] The technical solution of this utility model will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0046] To address the issues of low energy recovery efficiency and lack of hydraulic cylinder steering circuit in existing systems (patent document CN117419077A), this utility model provides a hydraulic system with energy recovery function. By eliminating the one-way throttle valve on the pipeline where the directional valve directly connects to the lifting cylinder is located, the energy recovery efficiency is improved. A hydraulic steering circuit is added and the hydraulic principle is optimized, reducing the overall machine procurement and maintenance costs, and expanding the application scenarios.

[0047] like Figure 1 As shown, the hydraulic system with energy recovery function provided in this embodiment of the present invention includes an oil tank 1, a pump motor 24, a first relief valve 22, a second relief valve 7, a first throttling element 21, a first reversing valve 19, a second reversing valve 17, a third reversing valve 6, a fourth reversing valve 12, a steering cylinder 14, a first lifting cylinder 8, a second lifting cylinder 9, a drive module, a control module, and an energy storage element. The pump motor 24 is driven by the drive module, which is electrically connected to the control module and the energy storage element. The control module is electrically connected to the electromagnets of the first reversing valve 19, the second reversing valve 17, the third reversing valve 6, and the fourth reversing valve 12. The drive module includes a motor 23 and a driver. In the lifting condition, the control module drives the motor 23 to rotate forward through the driver. In the descent energy recovery condition, the reverse electromotive force generated by the reverse rotation of the motor 23 is rectified and output by the driver to charge the energy storage element, thereby realizing potential energy recovery.

[0048] like Figure 1 As shown, the oil inlet of pump motor 24 is connected to oil tank 1, and the oil outlet of pump motor 24 is connected to the third port of first reversing valve 19 and the oil inlet of first relief valve 22; the second port of first reversing valve 19 is connected to the third port of second reversing valve 17, the second port and fourth port of second reversing valve 17 are respectively connected to port A and port B of steering cylinder 14, and the first port of second reversing valve 17 is connected to the second end of first throttling element 21, the oil outlet of first relief valve 22, and oil tank 1; the first throttling element 21... The first end is connected to the first port of the first directional valve 19; the fourth port of the first directional valve 19 is connected to the first port of the third directional valve 6 and the first port of the fourth directional valve 12; the second port of the third directional valve 6 is connected to the A port of the first lifting cylinder 8; the second port of the fourth directional valve 12 is connected to the A port of the second lifting cylinder 9; the second port of the third directional valve 6 is connected to the first port of the third directional valve 6 through the second overflow valve 7; the B port of the first lifting cylinder 8 and the B port of the second lifting cylinder 9 are connected to the atmosphere or the oil tank 1.

[0049] When the outlet pressure of the pump motor 24 rises abnormally due to sudden load changes, valve closure, or pipeline blockage, the first relief valve 22 opens to directly discharge high-pressure oil back to the oil tank 1, preventing damage to the pump motor 24, pipeline, or other components due to overpressure. The set pressure of the first relief valve 22 determines the maximum working pressure of the system and can maintain a constant system pressure. The second relief valve 7 can prevent the work platform from being overloaded (when the work platform is overloaded, the pressure in the rodless chamber of the first lifting cylinder 8 will increase, the second relief valve 7 will open, and the high-pressure oil will be directly discharged back to the oil tank 1); in addition, the scissor lift aerial work platform has an emergency descent function. The scissor frame is equipped with an emergency handle, which is connected to the manual control valve rod of the fourth directional valve 12 via an emergency cable. When the energy storage element is out of power or the electrical system fails, making it impossible to descent electrically, the operator can control the fourth directional valve 12 to switch directions by pulling the emergency handle on the scissor frame. The pressure oil in the rodless chamber of the second lifting cylinder 9 will flow back to the oil tank through the fourth directional valve 12. At this time, the weight of the work platform is on the first lifting cylinder 8, the pressure in the rodless chamber of the first lifting cylinder 8 will increase, the second relief valve 7 will open, and the pressure oil in the rodless chamber of the first lifting cylinder 8 will flow back to the oil tank through the second relief valve 7.

[0050] The hydraulic system of this utility model includes lifting mode, descent energy recovery mode, descent without energy recovery mode, and steering mode.

[0051] During the lifting operation, when the operating handle is set to the lifting action, the control module, based on the handle signal (i.e., the lifting command), controls the motor 23 to rotate forward via the driver, driving the pump motor 24 to rotate. At this time, the pump motor 24 functions as a pump, and the electromagnet S1 of the first reversing valve 19 is energized. The oil output from the pump motor 24 is divided into two paths after passing through the third and fourth ports of the first reversing valve 19: one path enters port A of the first lifting cylinder 8 via the third reversing valve 6, and the other path enters port A of the second lifting cylinder 9 via the fourth reversing valve 12. The piston rods of the first lifting cylinder 8 and the second lifting cylinder 9 extend, realizing the lifting action. Simultaneously, the air in the rod chambers of the first lifting cylinder 8 and the second lifting cylinder 9 is discharged to the atmosphere through port B. Figure 2 As shown.

[0052] During the energy recovery descent operation, when the operating handle is set to the descent position, the control module energizes the electromagnets S1, Y4, and Y3 of the first directional valve 19, the third directional valve 6, and the fourth directional valve 12 based on the handle signal (i.e., the descent command). Oil in the rodless chamber of the first lifting cylinder 8 flows out through the third directional valve 6, and oil in the rodless chamber of the second lifting cylinder 9 flows out through the fourth directional valve 12. The oil then flows into the pump motor 24 through the fourth and third ports of the first directional valve 19. At this time, the pump motor 24 functions as a hydraulic motor, driving the motor 23 to reverse and generate a reverse electromotive force. This reverse electromotive force is rectified by the driver to output DC power, charging the energy storage element and achieving energy recovery. The oil flowing from the pump motor 24 flows into the oil tank 1, realizing the descent action. Simultaneously, air enters the rod chambers of the first lifting cylinder 8 and the second lifting cylinder 9. Figure 3 As shown.

[0053] For debugging or certain fault modes, this utility model also provides a descent without energy recovery mode. Specifically, the control module controls only the electromagnet Y4 of the third reversing valve 6 and the electromagnet Y3 of the fourth reversing valve 12 to be energized according to the debugging mode or fault mode, entering the descent without energy recovery mode. In the descent without energy recovery mode, the operating handle is set to the descent action. The control module controls the electromagnet Y4 of the third reversing valve 6 and the electromagnet Y3 of the fourth reversing valve 12 to be energized according to the handle signal (i.e., the descent command) and the debugging mode (or fault mode). The oil in the rodless chamber of the first lifting cylinder 8 flows out through the third reversing valve 6, and the oil in the rodless chamber of the second lifting cylinder 9 flows out through the fourth reversing valve 12. After merging, the oil flows back to the oil tank 1 through the fourth port and the first port of the first reversing valve 19 and the first throttling element 21, realizing the descent action. Simultaneously, air enters the rod chambers of the first lifting cylinder 8 and the second lifting cylinder 9, such as... Figure 4 As shown. The first throttling element 21 provides throttling speed control function during descent without energy recovery.

[0054] Steering operations include left turn and right turn. In left turn mode, the operating handle is switched to the left turn position. The control module, based on the left turn command, controls motor 23 to rotate forward via the driver, driving pump motor 24 to rotate. At this time, pump motor 24 functions as a pump, and the electromagnet Y2 of the second directional valve 17 is energized. The oil output from pump motor 24 flows through the third and second ports of the first directional valve 19, and the third and fourth ports of the second directional valve 17 into port B of steering cylinder 14, pushing the piston rod to the left and driving the steering mechanism to achieve the left turn function. Figure 5As shown; when turning right, the operating handle is switched to the right turn position. The control module controls the motor 23 to rotate forward according to the right turn command through the driver, which drives the pump motor 24 to rotate. At this time, the pump motor 24 is used as a pump, and the electromagnet Y1 of the second reversing valve 17 is energized. The oil output by the pump motor 24 flows into the A port of the steering cylinder 14 through the third and second ports of the first reversing valve 19 and the third and second ports of the second reversing valve 17, pushing the piston rod to move to the right, thereby driving the steering mechanism to realize the right turn function.

[0055] In a specific embodiment of this utility model, a first check valve 20 is connected in parallel to both ends of the pump motor 24. The first check valve 20 serves as a bypass oil replenishment check valve, which can replenish oil when the pump motor 24 is used as a hydraulic motor and cavitation or poor oil suction occurs, thus preventing insufficient lubrication of the pump motor 24 due to lack of oil, which would affect its service life.

[0056] In a specific embodiment of this utility model, a second throttling element 15 is provided between port A of the steering cylinder 14 and the second port of the second directional valve 17, and a third throttling element 16 is provided between port B of the steering cylinder 14 and the fourth port of the second directional valve 17. The second throttling element 15 and the third throttling element 16 are used to provide a certain back pressure, thereby stabilizing the oil fluctuation and making the steering smoother.

[0057] In a specific embodiment of this utility model, the third port of the second directional valve 17 is connected to the first port of the second directional valve 17 through the third relief valve 18. When the pressure in the circuit where the third port of the second directional valve 17 is located exceeds the set value of the third relief valve 18, the third relief valve 18 opens, directly releasing the high-pressure oil to the oil tank 1, preventing the system from being damaged by excessive pressure.

[0058] In a specific embodiment of this utility model, a second check valve 26 and a third check valve 25 are connected in parallel on the pipeline connected to the fourth port of the first directional valve 19. The parallel second check valve 26 and the third check valve 25 can not only realize the normal lifting action, but also ensure that there is oil between the second check valve 26 and the third check valve 25 and the third directional valve 6 and the fourth directional valve 12. In this way, during the descent, at the moment of switching of the third directional valve 6 and the fourth directional valve 12, back pressure can be quickly established at the first port of the third directional valve 6 and the fourth directional valve 12, avoiding the jerking sensation caused by the initial fast speed followed by slow speed during descent.

[0059] In a specific embodiment of this utility model, a first safety valve 5 is provided at the first port of the third directional valve 6, and a second safety valve 13 is provided at the first port of the fourth directional valve 12. The first safety valve 5 and the second safety valve 13 can also be called explosion-proof valves, automatic shut-off valves, or maximum flow control valves. Their function is to shut off the descent circuit and prevent further potential safety accidents when the lifting and lowering circuit hose ruptures, as there is no back pressure or flow control in the lowering oil circuit.

[0060] Under normal descent conditions, the first safety valve 5 and the second safety valve 13 are always open. The energy consumed by the oil flowing through the first safety valve 5 and the second safety valve 13 is much less than the energy lost by the throttle valve. Therefore, compared with the existing system, the recoverable energy is increased and the energy recovery efficiency is improved. The first safety valve 5 and the second safety valve 13 can prevent rapid descent caused by pipeline rupture or motor 23 stall during descent conditions, thus improving safety.

[0061] In a specific embodiment of this utility model, the first reversing valve 19 is a two-position four-way proportional reversing valve. The system also includes a first sensor 11 and a second sensor electrically connected to the control module. The first sensor 11 is used to detect the platform load weight, and the second sensor is used to detect the ambient temperature inside the control module. The control module adjusts the opening of the first reversing valve 19 according to the platform load weight detected by the first sensor 11 and the ambient temperature detected by the second sensor to increase the energy recovery efficiency or prevent the voltage or current of energy recovery from exceeding the allowable value of the energy storage element. Specifically, when the platform load weight is less than the load threshold and the ambient temperature inside the control module is greater than the temperature threshold, the opening of the first reversing valve 19 is increased to increase the energy recovery efficiency; when the platform load weight is greater than or equal to the load threshold and the ambient temperature inside the control module is less than or equal to the temperature threshold, the opening of the first reversing valve 19 is decreased to prevent the voltage or current of energy recovery from exceeding the allowable value of the energy storage element and extend the service life of the energy storage element. In this embodiment, the load threshold is set to 80% of the rated load, and the temperature threshold is set to -10℃.

[0062] In this embodiment, the first sensor 11 is a pressure sensor, and the energy storage element is a power battery. The platform load weight is detected by the pressure sensor. When the platform load weight detected by the pressure sensor exceeds the set allowable load value, the control module issues an overload alarm signal, restricting the relevant actions of the vehicle.

[0063] In a specific embodiment of this utility model, the first sensor 11 is connected to the pipeline between port A of the second lifting cylinder 9 and port 2 of the fourth directional valve 12 via the fourth throttling element 10. The fourth throttling element 10 stabilizes oil fluctuations, thereby reducing pressure fluctuations and making the detection results of the first sensor 11 more stable.

[0064] In a specific embodiment of this utility model, the second directional valve 17, the third directional valve 6, and the fourth directional valve 12 are all solenoid directional valves. The second directional valve 17 is a three-position four-way solenoid directional valve, while the third directional valve 6 and the fourth directional valve 12 are both two-position two-way solenoid directional valves. The fourth directional valve 12 has manual control, which is used to lower the valve when the energy storage element is without power or the electrical system fails, preventing electrically controlled descent. An emergency pull cable is connected to the manual control valve stem of the fourth directional valve 12, and the descent is initiated by pulling the manual control valve stem. In another specific embodiment of this invention, the second directional valve 17 is a solenoid directional valve, while the third directional valve 6 and the fourth directional valve 12 are both electro-proportional directional valves.

[0065] In a specific embodiment of this utility model, a first filter 2 is provided on the oil outlet pipe of the oil tank 1, and a second filter 3 is provided on the oil return pipe of the oil tank 1. The oil tank 1, the B port of the first lifting cylinder 8 and the B port of the second lifting cylinder 9 are connected to the air filter 4.

[0066] In this embodiment, the pump motor 24 is a unidirectional pump motor or a bidirectional pump motor; the first throttling element 21, the second throttling element 15, the third throttling element 16 and the fourth throttling element 10 can be damping, orifice or flow valve.

[0067] The above description only discloses specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A hydraulic system with energy recovery function, characterized in that, The system includes an oil tank, a pump motor, a first overflow valve, a second overflow valve, a first throttling element, a first reversing valve, a second reversing valve, a third reversing valve, a fourth reversing valve, a steering cylinder, a first lifting cylinder, a second lifting cylinder, a drive module, a control module, and an energy storage element; the pump motor is driven by the drive module, the drive module is electrically connected to the control module and the energy storage element, and the control module is electrically connected to the electromagnets of the first, second, third, and fourth reversing valves; The oil inlet of the pump motor is connected to the oil tank, and the oil outlet of the pump motor is connected to the third port of the first reversing valve and the oil inlet of the first overflow valve; the second port of the first reversing valve is connected to the third port of the second reversing valve, the second port and the fourth port of the second reversing valve are respectively connected to the A port and the B port of the steering cylinder, the first port of the second reversing valve is connected to the second end of the first throttling element, the oil outlet of the first overflow valve and the oil tank; the first end of the first throttling element is connected to the first port of the first reversing valve. The fourth port of the first reversing valve is connected to the first port of the third reversing valve and the first port of the fourth reversing valve. The second port of the third reversing valve is connected to the A port of the first lifting cylinder, and the second port of the fourth reversing valve is connected to the A port of the second lifting cylinder. The second port of the third reversing valve is connected to the first port of the third reversing valve through the second relief valve. The B ports of the first lifting cylinder and the second lifting cylinder are connected to the atmosphere or the oil tank.

2. The hydraulic system with energy recovery function according to claim 1, characterized in that, A first check valve is connected in parallel to both ends of the pump motor.

3. The hydraulic system with energy recovery function according to claim 1, characterized in that, A second throttling element is provided between port A of the steering cylinder and the second port of the second directional valve, and a third throttling element is provided between port B of the steering cylinder and the fourth port of the second directional valve.

4. The hydraulic system with energy recovery function according to claim 1, characterized in that, The third port of the second reversing valve is connected to the first port of the second reversing valve through a third relief valve.

5. The hydraulic system with energy recovery function according to claim 1, characterized in that, A second check valve and a third check valve are connected in parallel on the pipeline connected to the fourth port of the first reversing valve.

6. The hydraulic system with energy recovery function according to claim 1, characterized in that, A first safety valve is provided at the first port of the third directional valve, and a second safety valve is provided at the first port of the fourth directional valve.

7. The hydraulic system with energy recovery function according to any one of claims 1 to 6, characterized in that, The first directional valve is an electro-proportional directional valve; The system also includes a first sensor and a second sensor electrically connected to the control module; the first sensor is used to detect the platform load weight, and the second sensor is used to detect the ambient temperature inside the control module. The control module is used to adjust the opening of the first reversing valve according to the platform load weight detected by the first sensor and the ambient temperature detected by the second sensor, so as to increase the energy recovery efficiency or prevent the voltage or current of energy recovery from exceeding the allowable value of the energy storage element.

8. The hydraulic system with energy recovery function according to claim 7, characterized in that, The first sensor is connected to the pipe between port A of the second lifting cylinder and port 2 of the fourth directional valve via the fourth throttling element.

9. The hydraulic system with energy recovery function according to claim 1, characterized in that, The second, third, and fourth directional control valves are all solenoid directional control valves; or, the second directional control valve is a solenoid directional control valve, and the third and fourth directional control valves are both electro-proportional directional control valves.

10. An aerial work platform, characterized in that, The platform includes a hydraulic system with energy recovery function as described in any one of claims 1 to 9.

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