Tower crane energy recovery system, tower crane energy recovery control method and tower crane

Abstract

The invention belongs to the technical field of operation machinery and provides a tower crane energy recovery system, a tower crane energy recovery control method and a tower crane. The system comprises a tower crane power unit, an energy conversion hydraulic loop, an energy recovery / utilization module and a controller. The energy conversion hydraulic circuit comprises a first motor and a second motor, a first oil port of the first motor is connected with a second oil port of the second motor, a second oil port of the first motor is connected with a first oil port of the second motor, and the first motor is further in transmission connection with the tower crane power unit. The energy recovery / utilization module comprises a motor and a charging and discharging energy storage module, the motor is in transmission connection with the second motor, and the controller is used for controlling the motor to be switched to a power generation mode when the tower crane is in a negative load working condition. The system not only can realize kinetic energy recovery when the tower crane is in a negative load working condition, but also can avoid hoisting stall.

Description

Technical Field

[0001] This invention belongs to the field of construction machinery technology, specifically relating to a tower crane energy recovery system, a tower crane energy recovery control method, and a tower crane. Background Technology

[0002] Currently, some tower cranes used in construction are engine-driven, and power is supplied to the working circuits (hoisting circuit, luffing circuit, slewing circuit, and auxiliary circuit) through a transfer case on the engine output shaft.

[0003] Tower cranes typically operate in two modes: power operation and load-bearing operation. Power operation refers to the engine consuming fuel to perform work during lifting, boom luffing, and slewing. Load-bearing operation refers to the situation where, during lowering and boom luffing, the weight of the load and the boom drives the corresponding motor in the hydraulic circuit to reverse, thus inputting torque (power) to the engine.

[0004] During the completion phase of high-rise buildings, auxiliary construction equipment needs to be dismantled, and tower cranes are often under heavy load. To prevent engine speed from running out of control, the system usually limits the descent speed or outward luffing speed of the load. This practice not only significantly reduces work efficiency but also causes a large amount of potential energy to be converted into heat energy dissipation through the speed limiting mechanism, making effective energy recovery impossible. Summary of the Invention

[0005] To address the aforementioned deficiencies or shortcomings, this invention provides a tower crane energy recovery system, a tower crane energy recovery control method, and a tower crane, aiming to solve the technical problems of low working efficiency and inability to effectively recover energy in existing tower cranes under heavy load conditions.

[0006] To achieve the above objectives, in one aspect, the present invention provides a tower crane energy recovery system, which includes a tower crane power unit, an energy conversion hydraulic circuit, an energy recovery / utilization module, and a controller. The tower crane power unit and the energy conversion hydraulic circuit include a first motor and a second motor. The first oil port of the first motor is connected to the second oil port of the second motor, and the second oil port of the first motor is connected to the first oil port of the second motor. The first motor is also connected to the tower crane power unit for transmission. The energy recovery / utilization module includes a motor and a charging / discharging energy storage module. The motor is connected to the second motor for transmission. The controller is used to control the motor to switch to power generation mode when the tower crane is under a negative load condition.

[0007] In the embodiment, the first oil port of the first motor and the second oil port of the second motor are connected by a first side oil circuit, the second oil port of the first motor and the first oil port of the second motor are connected by a second side oil circuit, and the tower crane energy recovery system further comprises an unloading oil circuit, one end of the unloading oil circuit is connected to the first side oil circuit and the second side oil circuit respectively, and the other end is connected to the oil tank, the unloading oil circuit is used for unloading the first side oil circuit and the second side oil circuit, and an unloading control valve is arranged on the unloading oil circuit, the unloading control valve is used for controlling the unloading oil circuit to be conducted or cut off.

[0008] In the embodiment, the tower crane energy recovery system further comprises a controllable overflow oil circuit, one end of the controllable overflow oil circuit is connected to the oil tank, and the other end is connected to the first side oil circuit and the second side oil circuit respectively, and a proportional overflow valve with adjustable overflow pressure is arranged on the controllable overflow oil circuit.

[0009] In the embodiment, the tower crane energy recovery system further comprises a supplement oil circuit, one end of the supplement oil circuit is connected to the oil tank, and the other end is connected to the first side oil circuit and the second side oil circuit respectively through a one-way valve.

[0010] To achieve the above-mentioned purpose, the application further provides a tower crane energy recovery control method, which is used for the tower crane energy recovery system described above, and the method specifically comprises: S100: obtaining an operation to be performed by the tower crane; S200A: when the tower crane is in a negative load working condition, judging whether the working condition of the tower crane and the state of the energy recovery / utilization module both satisfy the energy recovery condition; S300A-1: when the determination result is that the energy recovery condition is satisfied, controlling the motor to switch to a power generation mode, and limiting the maximum rotating speed of the motor within a first rotating speed; Wherein, the first rotating speed is the rotating speed corresponding to the motor when the flow output by the first motor rotation drives the second motor rotation.

[0011] In the embodiment, the tower crane energy recovery system further comprises an unloading oil circuit for unloading the energy conversion hydraulic circuit, and the unloading oil circuit is controllable, when the determination result is satisfied, the tower crane energy recovery control method further comprises: S300A-2: controlling the unloading oil circuit to be disconnected, so as to build pressure in the energy conversion hydraulic circuit.

[0012] In the embodiment, after judging whether the working condition of the tower crane and the state of the energy recovery / utilization module both satisfy the energy recovery condition, the method further comprises: S310A-1: when the determination result is that the energy recovery condition is not satisfied, and the working condition of the tower crane or the state of the energy recovery / utilization module does not satisfy an energy assisting condition, controlling the unloading oil circuit to be conducted.

[0013] In the embodiment, after the operation to be performed by the tower crane is acquired, the control method further comprises: S200B: judging whether the working condition of the tower crane and the state of the energy recovery / utilization module satisfy the energy assisting condition when the tower crane is in the working condition; S300B-1: if the result of the judgment is that the energy assisting condition is satisfied, controlling the motor to switch to the motor mode and controlling the unloading function of the energy conversion hydraulic circuit to be closed.

[0014] In the embodiment, when the result of the judgment is that the energy assisting condition is satisfied, the control method further comprises: S300B-2: controlling the rotating speed of the motor to be not lower than the second rotating speed; wherein the second rotating speed is the corresponding rotating speed of the first motor maintaining the required flow of the second motor when the second motor rotates at the driving rotating speed of the motor.

[0015] To achieve the above-mentioned purpose, the application further provides a tower crane, wherein the tower crane comprises the tower crane energy recovery system according to the above-mentioned tower crane energy recovery system.

[0016] Through the above-mentioned technical solution, the tower crane energy recovery system provided by the embodiment has the following beneficial effects: When the tower crane carries the load to perform the load descending or load amplitude changing operation, the tower crane is in the negative load working condition, at this time, the potential energy of the load will be input to the engine through the driving pump and the transfer case on the corresponding circuit. In this working condition, by controlling the motor to switch to the power generation mode, the power input to the engine from the load can be transmitted to the motor through the first motor and the second motor in turn, so as to drive the motor to rotate and generate electricity, so as to achieve the purpose of energy recovery, and the electricity generated by the motor can be stored through the charging and discharging energy storage module. When the energy recovery / utilization module performs energy recovery, it will increase the resistance of the load descending or amplitude changing to a certain extent, and the greater the speed of the load is, the stronger the resistance provided by the energy recovery / utilization module is. In this way, the movement speed of the load can be ensured to reach a certain threshold, the work efficiency is ensured, and the load speed is prevented from being lost, so that the work safety is ensured. In addition, the tower crane energy recovery system in the embodiment is provided with the energy conversion hydraulic circuit which is independent of the working circuit of the tower crane and is connected with the engine of the tower crane, so that the energy recovery of each working circuit can be realized by only one motor.

[0017] Other features and advantages of the application will be described in detail in the following specific embodiment part. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the application, but do not constitute a limitation on the application. In the drawings: Figure 1 is a hydraulic schematic diagram of a tower crane energy recovery system in an embodiment of the present application; Figure 2 is a relationship diagram of each working circuit in a tower crane and a tower crane energy recovery system in an embodiment of the present application; Figure 3 is a step diagram of a tower crane energy recovery control method when the tower crane is in a negative load working condition and external conditions meet energy recovery conditions in an embodiment of the present application; Figure 4 is a parallel step diagram of step S300A-1 in an embodiment of the present application; Figure 5 is a step diagram after step S200A when the tower crane is in a negative load working condition and external conditions do not meet energy recovery conditions in an embodiment of the present application; Figure 6 is a step diagram of a tower crane energy recovery control method when the tower crane is in a working condition and external conditions meet energy assistance conditions in an embodiment of the present application; Figure 7 is a parallel step diagram of step S300B-1 in an embodiment of the present application.

[0019] Reference Signs List 1, tower crane power unit; 11, engine; 12, transfer case; 2, energy conversion hydraulic circuit; 21, first motor; 22, second motor; 231, unloading oil path; 232, unloading control valve; 233, first check valve; 234, reversing control valve; 241, controllable overflow oil path; 242, proportional overflow valve; 251, oil supplementing oil path; 252, second check valve; A, first oil port; B, second oil port; 3, energy recovery / utilization module; 31, motor; 32, charge-discharge energy storage module; 4, hoisting working circuit; 5, luffing working circuit; 6, slewing working circuit; 7, auxiliary working circuit; 8, oil tank. DETAILED DESCRIPTION

[0020] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0021] The tower crane energy recovery system of the present application is described below with reference to the accompanying drawings.

[0022] The present application discloses a tower crane energy recovery system. As shown in Figure 1 and Figure 2 , the tower crane energy recovery system comprises a tower crane power unit 1, an energy conversion hydraulic circuit 2, an energy recovery / utilization module 3, and a controller.

[0023] The tower crane power unit 1 can be an engine driving architecture, that is, the tower crane power unit 1 comprises an engine 11 and a transfer case 12 connected to an output shaft of the engine 11, the transfer case 12 being used to distribute power output by the engine 11 to a slewing pump set in the slewing working circuit 6, an luffing pump set in the luffing working circuit 5, a hoisting pump set in the hoisting working circuit 4, and an auxiliary pump set in the auxiliary working circuit 7. Of course, the tower crane power unit 1 can also be an electric motor 31 driving architecture, and for the convenience of description, the following embodiments are exemplified by taking the engine driving architecture.

[0024] The energy conversion hydraulic circuit 2 comprises a first motor 21 and a second motor 22, a first oil port A of the first motor 21 being connected to a second oil port B of the second motor 22, and a second oil port B of the first motor 21 being connected to a first oil port A of the second motor 22 to form a closed hydraulic circuit, wherein the first motor 21 is also in driving connection with the engine 11 of the tower crane. It can be understood that the driving connection between the first motor 21 and the engine 11 of the tower crane can mean that the first motor 21 is directly connected to an output shaft of the engine 11, or the first motor 21 is indirectly connected to the engine 11 through the transfer case 12.

[0025] The energy recovery / utilization module 3 comprises an electric motor 31 and a charge-discharge energy storage module 32, and a slewing shaft of the electric motor 31 is in driving connection with the second motor 22.

[0026] The controller is used to control the electric motor 31 to switch to a power generation mode when the tower crane is in a negative load working condition.

[0027] When the tower crane carries a load to perform a load lowering operation or a luffing operation of the load outward, the tower crane is in a negative load working condition, and at this time, potential energy of the load can be input to the engine 11 through the driving pump on the corresponding circuit and the transfer case 12. In this working condition, by controlling the electric motor 31 to switch to the power generation mode, the power input to the engine 11 from the load can be sequentially transmitted to the electric motor 31 through the first motor 21 and the second motor 22, so as to drive the electric motor 31 to rotate and generate electricity, thereby achieving the purpose of energy recovery, and the electricity generated by the electric motor 31 can be stored through the charge-discharge energy storage module 32. In the process of energy recovery, the energy recovery / utilization module 3 can increase the resistance of the load lowering or luffing to a certain extent, and the greater the speed of the load, the stronger the resistance provided by the energy recovery / utilization module 3, so that the speed of the load can reach a certain threshold value to ensure the work rate, and the load can be prevented from stalling to ensure the safety of the work. In addition, the tower crane energy recovery system in the embodiment is provided with the energy conversion hydraulic circuit 2 independent of the working circuits of the tower crane, the first motor 21 is in driving connection with the engine 11 of the tower crane, and only one electric motor 31 is needed to achieve the energy recovery of the working circuits.

[0028] As Figure 1 and Figure 2As shown, in this embodiment, the controller is specifically configured as follows: Receives a command to lower the load or a command to extend the load outwards; Confirm that the tower crane's operating condition and the status of energy recovery / utilization module 3 both meet the energy recovery conditions; Generate energy recovery instructions; In response to the energy recovery command, the motor 31 is switched to the power generation mode according to the energy recovery command.

[0029] When the operator operates the handle or presses the corresponding button, causing the controller to receive the command to lower the load or the command to extend the load outward, the controller will control the engine 11 and the transfer case 12 to output power to the corresponding circuit. At the same time, the controller will also detect and determine whether the tower crane's operating conditions and the status of the energy recovery / utilization module 3 meet the energy recovery conditions.

[0030] When the weight of the lifted load reaches the set threshold and all components on the tower crane are functioning normally, it indicates that the tower crane meets the energy recovery conditions. When the motor 31 and the charging / discharging energy storage module 32 are functioning normally and the charging / discharging energy storage module 32 is allowed to charge, it indicates that the energy recovery / utilization module 3 meets the energy recovery conditions.

[0031] When both the tower crane and the energy recovery / utilization module 3 meet the requirements, the motor 31 can be switched to the power generation mode to realize the energy recovery of the potential energy of the suspended load. like Figure 1 and Figure 2 As shown, in this embodiment, the first oil port A of the first motor 21 and the second oil port B of the second motor 22 are connected via a first side oil circuit, and the second oil port B of the first motor 21 and the first oil port A of the second motor 22 are connected via a second side oil circuit. The tower crane energy recovery system also includes an unloading oil circuit 231 for unloading the first and second side oil circuits. One end of the unloading oil circuit 231 is connected to both the first and second side oil circuits, and the other end is connected to the oil tank 8. An unloading control valve 232 is provided on the unloading oil circuit 231. The unloading control valve 232 is used to control the opening or closing of the unloading oil circuit 231. When the tower crane's operating condition or the state of the energy recovery / utilization module 3 does not meet the energy recovery conditions, the unloading control valve 232 can be opened to control the unloading of the first and second side oil circuits.

[0032] By unloading the first and second side oil circuits, both the first and second side oil circuits can be kept as low-pressure oil circuits. When the engine 11 outputs power, the first motor 21 rotates with low resistance, avoiding the transmission of power from the first motor 21 to the second motor 22, which would increase the load on the engine 11.

[0033] In this embodiment, the unloading control valve 232 can be a conventional on / off valve or a proportional valve, or the unloading control valve 232 can also be an adjustable relief valve with overflow pressure regulation function. By using an adjustable relief valve, the unloading control function of the energy conversion hydraulic circuit 2 can be combined with the overflow safety protection function of the energy conversion hydraulic circuit 2.

[0034] like Figure 1 As shown, taking one embodiment of the adjustable relief valve as an example, the inlet of the adjustable relief valve is connected to the first side oil circuit and the second side oil circuit, and the outlet is connected to the oil tank 8. The adjustable relief valve also includes an overflow pressure hydraulic control terminal and a first overflow opening control terminal. The oil circuit of the first overflow opening control terminal is connected to the inlet of the adjustable relief valve. A reversing control valve 234 is provided on the connecting oil circuit of the overflow pressure hydraulic control terminal. The reversing control valve 234 is connected to the pilot oil circuit and the return oil circuit respectively. The reversing control valve 234 is used to control the overflow pressure hydraulic control terminal to selectively conduct one of the pilot oil circuit and the return oil circuit. By changing the oil pressure of the overflow pressure hydraulic control terminal, the overflow opening pressure of the adjustable relief valve can be changed accordingly, thereby realizing the adjustment of the maximum working pressure of the energy conversion hydraulic circuit 2. When the overflow pressure hydraulic control terminal is connected to the return oil circuit, the adjustable relief valve can be in the open state, and the entire energy conversion hydraulic circuit 2 is in the depressurized state.

[0035] like Figure 1 As shown, in this embodiment, the controller is also used to control the unloading control valve 232 to shut off when the tower crane's operating status or the energy recovery 3 / utilization module 3's status meets the energy recovery conditions. By controlling the unloading control valve 232 to shut off, the pressure build-up control of the energy conversion hydraulic circuit 2 can be realized, thereby ensuring that power is smoothly transmitted from the first motor 21 to the second motor 22.

[0036] like Figure 1 As shown, in this embodiment, one end of the unloading oil passage 231 can be connected to the oil tank 8, and the other end can be connected unidirectionally to the first side oil passage and the second side oil passage via a shuttle valve or two sets of first check valves 233. When the unloading oil passage 231 is connected to both the first side oil passage and the second side oil passage via the first check valve 233, the first check valve 233 needs to be configured to open when hydraulic oil flows from the end of the unloading oil passage 231 near the first side oil passage or the second side oil passage to the oil tank 8 and then close in the reverse direction. By using the shuttle valve or two sets of first check valves 233, mutual oil leakage between the first side oil passage and the second side oil passage can be prevented when pressure is released.

[0037] like Figure 1 As shown, in this embodiment, the tower crane energy recovery system also includes a controllable overflow oil circuit 241. One end of the controllable overflow oil circuit 241 is connected to the oil tank 8, and the other end is connected to the first side oil circuit and the second side oil circuit respectively. The controllable overflow oil circuit 241 is provided with a proportional overflow valve 242 with adjustable overflow pressure.

[0038] Specifically, the proportional relief valve 242 is equipped with an electro-proportional control terminal and a second relief opening control terminal. The oil circuit of the second relief opening control terminal is connected to the oil inlet of the proportional relief valve 242. When the electro-proportional control terminal receives different current inputs to the electromagnet, the relief opening pressure of the proportional relief valve 242 can be adjusted. The relief opening pressure of the proportional relief valve 242 needs to be much lower than the relief opening pressure of the adjustable relief valve. During the pressure build-up of the energy conversion hydraulic circuit 2, the adjustable relief valve is used as a safety valve.

[0039] By setting a proportional relief valve 242, when the motor 31 is recovering energy, a portion of the hydraulic oil can be controlled to drive the motor 31 to rotate, and a portion of the hydraulic oil can overflow back to the oil through the controllable relief oil circuit 241. By adjusting the opening pressure of the proportional relief valve 242, the opening pressure and overflow flow of the controllable relief oil circuit 241 can be changed, thereby adjusting the power generation of the energy recovery / utilization module 3.

[0040] In this embodiment, the controllable overflow oil circuit 241 can also be connected unidirectionally to the first side oil circuit and the second side oil circuit via a shuttle valve or two sets of check valves. The unidirectional connection can prevent oil leakage between the first side oil circuit and the second side oil circuit. Furthermore, the controllable overflow oil circuit 241 and the unloading oil circuit 231 can share a shuttle valve or a check valve.

[0041] In addition, this embodiment combines speed limiting control of motor 31 with adjustment of opening pressure of controllable overflow oil circuit 241 to adjust the running resistance torque of first motor 21 during energy recovery and to adjust the output torque of first motor 21 during energy assistance.

[0042] like Figure 3 As shown, in this embodiment, the tower crane energy recovery system also includes a replenishment oil circuit 251. One end of the replenishment oil circuit 251 is connected to the oil tank 8, and the other end is connected to the first side oil circuit and the second side oil circuit respectively through a second one-way valve 252. The second one-way valve 252 is configured to open when hydraulic oil flows from the end of the replenishment oil circuit 251 near the oil tank 8 to the first side oil circuit or the second side oil circuit, and to close in the reverse direction. Through the replenishment oil circuit 251 and the second one-way valve 252, one-way replenishment of oil to the energy conversion hydraulic circuit 2 can be realized.

[0043] In this embodiment, the charge / discharge energy storage module 32 includes a frequency converter for AC / DC conversion and a battery module. When the motor 31 generates electricity, the frequency converter can convert the AC power generated by the motor 31 into DC power and supply it to the battery module for storage. When the motor 31 is driven, the DC power in the battery module is converted into AC power by the frequency converter and supplied to the motor 31.

[0044] like Figure 4As shown, to achieve the above objectives, the present invention also provides a tower crane energy recovery control method, used in accordance with the tower crane energy recovery system described above, the method specifically comprising: S100: Obtain the operation to be performed by the tower crane; S200A: When the tower crane is under a negative load, determine whether the working status of the tower crane and the status of the energy recovery / utilization module 3 both meet the energy recovery conditions. S300A-1: When the determination result is that the energy recovery condition is met, control motor 31 to switch to power generation mode and limit the maximum speed of motor 31 to a first speed. The first rotational speed is the rotational speed of motor 31 when the flow output from the first motor 21 drives the second motor 22 to rotate.

[0045] This method achieves energy recovery of the potential energy of the suspended load by controlling motor 31 to switch to generator mode when the tower crane is under negative load and the operating conditions or status of each hardware component meet the energy recovery conditions. During the energy recovery process, this method limits the speed of the second motor 22 within a first speed range, ensuring that the power of the first motor 21 is always greater than the power of the second motor 22. This guarantees that the second motor 22 and motor 31 are always driven at a uniform speed, preventing the second motor 22 from experiencing sudden changes in speed.

[0046] In this embodiment, the negative load condition of the tower crane mainly refers to the situation where the tower arm drives the load to descend or the tower arm drives the load to change amplitude outward.

[0047] like Figure 5 and Figure 6 As shown, in this embodiment, the tower crane energy recovery system further includes an unloading oil circuit 231 for unloading the energy conversion hydraulic circuit 2. The unloading oil circuit 231 can be switched on and off. When the determination result is satisfied, the tower crane energy recovery control method further includes: S300A-2: Controls the disconnection of the unloading oil circuit 231, causing the energy conversion hydraulic circuit 2 to build up pressure.

[0048] In this embodiment, after step S200A, the tower crane energy recovery control method further includes: S310A-1: When the judgment result is that the energy recovery conditions are not met, and the tower crane's operating condition or the status of the energy recovery / utilization module does not meet the energy assistance conditions, the unloading oil circuit 231 is turned on.

[0049] Since the first motor 21 is directly or indirectly connected to the engine 11, it will rotate when the engine 11 outputs power to the working circuit. To avoid the first motor 21 increasing the load on the engine 11 due to damped motion, the unloading oil circuit 231 can be opened when the engine 11 outputs power. At this time, both the first and second oil circuits of the energy conversion hydraulic circuit 2 are in a depressurized state, and only the first motor 21 idles in the energy conversion hydraulic circuit 2.

[0050] When energy recovery is required, the unloading oil circuit 231 can be shut off. At this time, the energy conversion hydraulic circuit 2 is closed, and the power of the first motor 21 can be smoothly transmitted to the second motor 22 through the hydraulic oil in the oil circuit.

[0051] like Figure 7 As shown in this embodiment, after obtaining the operation to be performed by the tower crane, the control method further includes: S200B: When the tower crane is in operation, determine whether the working status of the tower crane and the status of the energy recovery / utilization module 3 meet the energy assistance conditions. S300B-1: If the determination result is that the energy assistance condition is met, control motor 31 to switch to motor 31 mode and control the unloading function of energy conversion hydraulic circuit 2 to be turned off.

[0052] The conditions for energy assistance include: all components on the tower crane are in normal condition; when engine 11 outputs power to the working circuit, the load on engine 11 is greater than a set threshold; when engine 11 outputs power to the working circuit, or the battery module has sufficient charge. Among these, if the battery module's charge is greater than a set value (e.g., greater than 85%), the system can switch to energy assistance mode even if the load on engine 11 is less than the set threshold.

[0053] When the tower crane's operating conditions and the status of the energy recovery 3 / utilization module 3 meet the energy assistance conditions, the tower crane's energy recovery system can be switched to assistance mode. In assistance mode, the battery module supplies power to the motor 31 to drive the motor 31 to rotate. The power output of the motor 31 can be transmitted to the power shaft through the second motor 22 and the first motor 21, thereby sharing the load of the engine 11.

[0054] In this embodiment, when the system switches to the assist mode, it is necessary to control the unloading oil circuit 231 to be cut off.

[0055] In this embodiment, the working condition of the tower crane refers to the condition of lifting the load or the lifting load changing its amplitude inward.

[0056] like ​ As shown, in this embodiment, when the determination result is that the energy assistance condition is met, the control method further includes: S300B-2: Control the speed of motor 31 to be no less than the second speed; The second rotational speed is the rotational speed at which the first motor 21 maintains the required flow rate of the second motor 22 when the second motor 22 rotates at the driving speed of the motor 31.

[0057] In the boost mode, by limiting the speed of the second motor 22 to a second speed range, the power of the second motor 22 can be controlled to always be greater than the power of the first motor 21, ensuring that the first motor 21 can be driven smoothly.

[0058] In this embodiment, the electrical energy in the battery module is used not only to power the engine 11, but also to power the tower crane's electronic control system and electrical equipment.

[0059] The control method in this embodiment will be explained below in conjunction with the specific working process of the tower crane energy recovery system.

[0060] In energy recovery mode, the first motor 21 operates as a pump and outputs hydraulic oil. The second motor 22 is driven, which in turn drives the motor 31 to rotate and generate electricity, thereby recovering the potential energy of the suspended load. In this mode, because the speed of the motor 31 is limited to a first speed range, the power output of the first motor 21 is greater than the power absorbed by the second motor 22. The hydraulic oil output by the first motor 21 can build up a higher pressure to provide sufficient driving force for the rotation of the second motor 22. This system, by setting a controllable overflow oil circuit 241, allows the hydraulic oil output by the first motor 21, except for the portion used to drive the rotation of the second motor 22, to overflow through the proportional overflow valve 242 on the controllable overflow oil circuit 241. By adjusting the overflow pressure of the proportional overflow valve 242, the working pressure of the energy conversion hydraulic circuit 2 can be adjusted, thereby adjusting the resistance torque of the first motor 21 and the power generation of the motor 31.

[0061] In power-assisted mode, the battery module supplies power to motor 31, which drives the second motor 22 to rotate. The second motor 22 outputs hydraulic oil and drives the first motor 21 to rotate through the energy conversion hydraulic circuit 2, thereby providing power-assisted torque to the engine 11. In this operating condition, since the speed of motor 31 is limited to no less than the second speed, the power output of the second motor 22 will be greater than that of the first motor 21, ensuring that the first motor 21 is driven smoothly. The working pressure of the energy conversion hydraulic circuit can be adjusted through the controllable overflow oil circuit, thereby adjusting the output torque of the first motor 21.

[0062] To achieve the above objectives, the present invention also provides a tower crane, wherein the tower crane includes the tower crane energy recovery system according to the above-described embodiments. Since the tower crane adopts all the technical solutions of the above embodiments, it possesses at least the beneficial effects brought about by the above embodiments, and will not be repeated here.

[0063] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0064] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0066] Although embodiments of the present invention have been described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A tower crane energy recovery system, characterized in that, The tower crane energy recovery system includes: Tower crane power unit (1); The energy conversion hydraulic circuit (2) includes a first motor (21) and a second motor (22). The first oil port (A) of the first motor (21) is connected to the second oil port (B) of the second motor (22), and the second oil port (B) of the first motor (21) is connected to the first oil port (A) of the second motor (22). The first motor (21) is also connected to the tower crane power unit (1) via transmission. The energy recovery / utilization module (3) includes a motor (31) and a charge / discharge energy storage module (32), wherein the motor (31) is connected to the second motor (22) in a transmission connection; The controller is used to control the motor (31) to switch to power generation mode when the tower crane is under a negative load.

2. The tower crane energy recovery system according to claim 1, characterized in that, A first side oil passage is provided between the first oil port (A) of the first motor (21) and the second oil port (B) of the second motor (22), and a second side oil passage is provided between the second oil port (B) of the first motor (21) and the first oil port (A) of the second motor (22). The tower crane energy recovery system also includes an unloading oil passage (231). One end of the unloading oil passage (231) is connected to the first side oil passage and the second side oil passage respectively, and the other end is connected to the oil tank (8). The unloading oil passage (231) is used to unload the first side oil passage and the second side oil passage. An unloading control valve (232) is provided on the unloading oil passage (231). The unloading control valve (232) is used to control the unloading oil passage (231) to be open or closed.

3. The tower crane energy recovery system according to claim 2, characterized in that, The tower crane energy recovery system also includes a controllable overflow oil circuit (241), one end of which is connected to the oil tank (8), and the other end is connected to the first side oil circuit and the second side oil circuit respectively. The controllable overflow oil circuit (241) is equipped with a proportional overflow valve (242) with adjustable overflow pressure.

4. The tower crane energy recovery system according to claim 2, characterized in that, The tower crane energy recovery system also includes a replenishment oil circuit (251), one end of which is connected to the oil tank (8), and the other end is connected to the first side oil circuit and the second side oil circuit respectively through a second check valve (252).

5. A tower crane energy recovery control method, used in the tower crane energy recovery system according to any one of claims 1 to 4, characterized in that, The tower crane energy recovery control method includes: Obtain the operation that the tower crane needs to perform; When the tower crane is under negative load, determine whether the working status of the tower crane and the status of the energy recovery / utilization module (3) both meet the energy recovery conditions; When the determination result is that the energy recovery conditions are met, the motor (31) is controlled to switch to the power generation mode, and the maximum speed of the motor (31) is limited to the first speed. Wherein, the first rotational speed is the rotational speed of the motor (31) when the flow output of the first motor (21) drives the second motor (22) to rotate.

6. The tower crane energy recovery control method according to claim 5, characterized in that, The tower crane energy recovery system also includes an unloading oil circuit (231) for unloading the energy conversion hydraulic circuit (2). The unloading oil circuit (231) can be switched on and off. When the determination result is satisfied, the tower crane energy recovery control method further includes: Disconnect the unloading oil circuit (231) to pressurize the energy conversion hydraulic circuit (2).

7. The tower crane energy recovery control method according to claim 6, characterized in that, After determining whether the tower crane's operating status and the status of the energy recovery / utilization module (3) both meet the energy recovery conditions, the process further includes: When the determination result is that the energy recovery conditions are not met, and the tower crane's operating condition or the status of the energy recovery / utilization module does not meet the energy assistance conditions, the unloading oil circuit (231) is controlled to be turned on.

8. The tower crane energy recovery control method according to claim 6, characterized in that, After obtaining the operation to be performed by the tower crane, the tower crane energy recovery control method further includes: When the tower crane is in working condition, determine whether the working condition of the tower crane and the state of the energy recovery / utilization module (3) meet the energy assistance conditions; If the determination result is that the energy assistance condition is met, control the motor (31) to switch to motor (31) mode, and control the unloading function of the energy conversion hydraulic circuit (2) to be turned off.

9. The tower crane energy recovery control method according to claim 8, characterized in that, When the determination result is that the energy assistance condition is met, the tower crane energy recovery control method further includes: Control the speed of the motor (31) to be no less than the second speed; Wherein, the second rotational speed is the rotational speed at which the first motor (21) maintains the required flow rate of the second motor (22) when the second motor (22) rotates at the driving speed of the motor.

10. A tower crane, characterized in that, Including the tower crane energy recovery system according to any one of claims 1 to 4.

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