Hydraulic system for hoisting equipment

Abstract

The invention relates to a hydraulic system for hoisting equipment. The hydraulic system comprises an execution unit, a power unit and a control unit, wherein the execution unit comprises an oil cylinder, the power unit comprises a first closed pump and an oil supplementing pump, and the control unit comprises a reversing valve. Compared with the prior art, the oil supplementing pump is connected to the first closed pump and the oil return pipeline of the oil cylinder, and when less oil discharged by the rod cavity of the oil cylinder is not enough to fill the oil suction port of the first closed pump, the oil supplementing pump can immediately supplement a medium to the main loop to prevent the closed pumps from sucking air; meanwhile, the overflow valve is arranged on the oil return pipeline, and when more oil discharged by the rodless cavity of the oil cylinder exceeds the oil suction capacity of the closed pump, redundant high-pressure oil can be unloaded through the overflow valve; the specific matching structure of the first closed pump, the oil supplementing pump and the overflow valve dynamically balances the flow profit and loss caused by the area difference of the oil cylinders, so that the closed pumps can stably drive the asymmetrically executed oil cylinders, and the energy-saving advantage of a closed system is reserved to a certain extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hoisting equipment, in particular to a hydraulic system for hoisting equipment. BACKGROUND

[0002] The hydraulic system of hoisting equipment is a power system that converts mechanical energy into hydraulic energy by using the principle of hydraulic transmission, and drives the execution element to complete complex actions such as hoisting, amplitude changing, rotating, telescoping, etc. by controlling the pressure, flow and direction of hydraulic oil. The system is usually composed of a hydraulic pump, control valves, hydraulic cylinders or hydraulic motors, an oil tank, pipelines and auxiliary elements, and is widely used in hoisting equipment in various fields.

[0003] In related technologies, the crane usually adopts an open system with simple structure, low cost and good heat dissipation, but it has some inherent shortcomings, such as large overflow loss and throttling loss after the oil flows back to the oil tank after work, low energy utilization rate, and easy to cause the oil temperature to rise.

[0004] Therefore, it is necessary to develop a new type of hydraulic system for hoisting equipment to improve some problems existing in the related art. SUMMARY

[0005] The purpose of the present application is to provide a hydraulic system for hoisting equipment, which can reduce the energy loss of the hydraulic system in the hoisting equipment.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] The present application provides a hydraulic system for hoisting equipment, comprising:

[0008] an execution unit;

[0009] a power unit connected to the execution unit for providing driving medium;

[0010] a control unit arranged between the execution unit and the power unit for controlling the execution unit;

[0011] Wherein, the execution unit comprises a cylinder, the power unit comprises a first closed pump and a oil supplement pump, and the control unit comprises a reversing valve; the reversing valve is arranged between the cylinder and the first closed pump for controlling the bidirectional movement of the piston rod of the cylinder; the oil supplement pump is connected to the oil return pipeline between the cylinder and the first closed pump for supplementing oil to the first closed pump when the rod cavity of the cylinder discharges oil; an overflow valve is further arranged on the oil return pipeline for overflow when the rodless cavity of the cylinder discharges oil.

[0012] Further, the execution unit comprises a hoisting motor, and the power unit comprises a second closed pump connected to the hoisting motor and used for connecting a winch of the hoisting device to hoist the heavy object.

[0013] Further, the second closed pump is connected to the oil cylinder, and the first closed pump is connected to the hoisting motor.

[0014] Further, the execution unit comprises a first hoisting motor and a second hoisting motor, and the power unit comprises a second closed pump; the second closed pump is connected to the first hoisting motor through a first electromagnetic valve, and the second closed pump is further connected to the second hoisting motor through the first electromagnetic valve and a second electromagnetic valve.

[0015] Further, the number of the second hoisting motor is at least two.

[0016] Further, the power unit comprises a third closed pump, and the control unit comprises an accumulator; the third closed pump is connected to the accumulator, the first hoisting motor and the second hoisting motor respectively, and the accumulator is connected to the second hoisting motor.

[0017] Further, the accumulator is a double-piston accumulator, and the air cavity of the accumulator is connected to a nitrogen bottle group.

[0018] Further, the motion reference unit is connected to the controller, and the controller is connected to the first hoisting motor and the second closed pump respectively, so as to compensate the lifting motion of the hoisted heavy object according to the wave motion.

[0019] Further, the execution unit comprises a slewing motor, and the first closed pump is connected to the slewing motor and used for driving the slewing action of the lifting arm of the hoisting device.

[0020] Further, the oil cylinder comprises an amplitude-changing oil cylinder or a folding arm oil cylinder; the amplitude-changing oil cylinder is used for driving the pitching action of the lifting arm of the hoisting device; and the folding arm oil cylinder is used for driving the folding and unfolding action of the lifting arm of the hoisting device.

[0021] Compared with the prior art, the hydraulic system for the hoisting device has the following beneficial effects:

[0022] 1. The hydraulic system for hoisting equipment provided by the application comprises an execution unit, a power unit and a control unit, wherein the execution unit comprises a cylinder, the power unit comprises a first closed pump and a supplementary oil pump, and the control unit comprises a reversing valve; the supplementary oil pump is connected to the oil return pipeline of the first closed pump and the cylinder, and when the oil cylinder rod cavity discharges insufficient oil to fill the oil suction port of the first closed pump, the supplementary oil pump can instantly supplement the medium to the main circuit to prevent the closed pump from being sucked empty; at the same time, an overflow valve is arranged on the oil return pipeline, and when the oil cylinder rod cavity discharges more oil than the oil suction capacity of the closed pump, the excess high-pressure oil can be discharged through the overflow valve; the specific matching structure of the first closed pump, the supplementary oil pump and the overflow valve dynamically balances the flow gain and loss caused by the area difference of the cylinder, so that the closed pump can stably drive the asymmetric execution cylinder, thereby retaining the energy-saving advantage of the closed system to a certain extent and realizing the reduction of energy loss.

[0023] 2. The second closed pump is connected to the cylinder, the first closed pump is connected to the lifting motor, the execution unit comprises first and second lifting motors, and the power unit comprises a second closed pump; the second closed pump is connected to the first lifting motor through a first electromagnetic valve, and the second closed pump is further connected to the second lifting motor through a second electromagnetic valve after the first electromagnetic valve, so that multiple pump sources and execution components are cross-connected with each other, thereby enhancing the flexibility and reliability of the system.

[0024] 3. The number of second lifting motors is at least two, which can make the motors share the load torque in parallel and realize dynamic matching of power output and actual load demand.

[0025] 4. The third closed pump is connected to the accumulator, the first lifting motor and the second lifting motor, respectively, the accumulator is connected to the second lifting motor, and the accumulator is a double-piston accumulator with gas as the compressible medium, which can automatically suppress the pressure pulsation and flow mutation caused by waves without external energy input, thereby isolating the influence of ship motion on the hoisted load in passive mode and realizing smooth wave compensation effect.

[0026] 5. The motion reference unit is connected to the controller, and the controller is connected to the first lifting motor and the second closed pump, respectively, based on real-time feedback, so that the actuator can actively generate a motion equal in size and opposite in direction to the disturbance caused by waves, thereby canceling the fluctuation displacement and keeping the position of the hoisted load in the inertial space relatively static in dynamic sea conditions, thereby significantly improving the safety and accuracy of the operation. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The figure is the hydraulic schematic diagram of the hydraulic system for hoisting equipment in the embodiment of the application.

[0028] Reference signs:

[0029] 11, oil makeup pump; 12, control pump; 13, third closed pump; 14, second closed pump; 15, first closed pump;

[0030] 21, check valve; 22, check valve; 23, check valve; 24, check valve; 25, check valve; 26, check valve; 27, check valve; 28, check valve; 29, check valve; 210, check valve; 211, check valve; 212, check valve; 213, check valve; 214, check valve;

[0031] 31, overflow valve; 32, overflow valve; 33, overflow valve; 34, overflow valve; 35, overflow valve; 36, overflow valve; 37, overflow valve;

[0032] 41, solenoid valve; 42, solenoid valve; 43, solenoid valve; 44, solenoid valve; 45, solenoid valve; 46, solenoid valve; 47, solenoid valve; 48, solenoid valve; 49, solenoid valve; 410, solenoid valve; 411, solenoid valve; 412, solenoid valve; 413, solenoid valve; 414, solenoid valve;

[0033] 51, proportional valve; 52, proportional valve; 53, proportional valve;

[0034] 61, hydraulic lock; 62, hydraulic lock; 63, hydraulic lock;

[0035] 7, cooler; 8, accumulator; 9, gas cylinder group;

[0036] 101, second hoisting motor; 102, second hoisting motor; 103, first hoisting motor;

[0037] 111, luffing oil cylinder; 112, folding arm oil cylinder;

[0038] 12, slewing motor. DETAILED DESCRIPTION

[0039] The present application will be described in detail below with reference to the drawings and specific embodiments. The embodiments are implemented on the basis of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0040] The embodiment of the present application provides a hydraulic system for a hoisting device, which comprises:

[0041] an execution unit;

[0042] a power unit connected to the execution unit, configured to provide driving medium;

[0043] a control unit arranged between the execution unit and the power unit, configured to control the execution unit;

[0044] The execution unit comprises a cylinder, the power unit comprises a first closed pump 15 and an oil supplement pump 11, and the control unit comprises a reversing valve; the reversing valve is arranged between the cylinder and the first closed pump 15 and is used for controlling the bidirectional movement of the piston rod of the cylinder; the oil supplement pump 11 is connected to an oil return pipeline between the cylinder and the first closed pump 15 and is used for supplementing oil to the first closed pump 15 when the rod cavity of the cylinder discharges oil; and an overflow valve 37 is further arranged on the oil return pipeline and is used for overflowing when the rodless cavity of the cylinder discharges oil.

[0045] In some specific embodiments, when the first closed pump 15 supplies oil to the luffing cylinder 111 and the jib cylinder 112 through the electromagnetic valve 49, because the area of the rod cavity of the cylinder is smaller than the area of the rodless cavity, when the cylinder discharges oil from the rodless cavity and discharges oil from the rod cavity, the oil intake of the cylinder is greater than the oil discharge, the low-pressure side of the closed loop is empty of oil, at this time, the oil supplement pump 11 supplements oil to the low-pressure side of the closed pump through the one-way valve 21, and specifically, the hydraulic oil supplements the first closed pump 15B through the one-way valve 25 or supplements the first closed pump 15A through the one-way valve 26 to prevent air suction; when the cylinder discharges oil from the rod cavity and discharges oil from the rodless cavity, the oil intake of the cylinder is smaller than the oil discharge, the low-pressure side of the closed loop is excessive in oil, the cylinder is pressurized, and when the pressure reaches the set value of the overflow valve 37, the overflow valve 37 is opened, and the excess oil is returned to the oil tank.

[0046] In some embodiments of the application, the execution unit comprises a lifting motor, the power unit comprises a second closed pump 14, and the second closed pump 14 is connected to the lifting motor and is used for connecting the winch of the hoisting equipment to hoist heavy objects.

[0047] In some embodiments of the application, the second closed pump 14 is connected to the cylinder, and the first closed pump 15 is connected to the lifting motor.

[0048] In some embodiments of the application, the power unit comprises a third closed pump 13, and the control unit comprises an accumulator 8; the third closed pump 13 is connected to the accumulator 8, the first lifting motor and the second lifting motor respectively, and the accumulator 8 is connected to the second lifting motor.

[0049] In some embodiments of the application, the number of the second lifting motor is at least two.

[0050] In some embodiments, the execution unit comprises two second lifting motors, one first lifting motor 103, one luffing cylinder 111, one folding cylinder 112 and one slewing motor 12. The output shafts of the second lifting motor 101, the second lifting motor 102 and the first lifting motor 103 are connected to the drum of the winch through transmission. The hoisting device comprises at least two booms and a slewing platform, the two ends of one boom are respectively hinged to the other boom and the slewing platform, the luffing cylinder 111 is connected to the slewing platform and the boom to drive the boom to pitch up and down relative to the slewing platform, the folding cylinder 112 is connected to the two booms to drive the angle between the two booms to change. The slewing motor 12 is connected to the slewing platform to drive the boom to slew.

[0051] In some embodiments, the reversing valve is an electro-hydraulic proportional directional valve, which comprises a proportional valve 51, a proportional valve 52 and a proportional valve 53, which are respectively connected to the working oil ports of the luffing cylinder 111, the folding cylinder 112 and the slewing motor 12 to simultaneously realize positive and reverse actions and control the execution speed.

[0052] In some embodiments, a hydraulic lock 61 is arranged between the proportional valve 51 and the luffing cylinder 111 to prevent the luffing cylinder 111 from moving under the action of external load. The connection mode and principle of the hydraulic lock 62 and the hydraulic lock 63 are similar to those of the hydraulic lock 61, which are not described here again. Figure 1

[0053] In some embodiments, the power unit comprises a first closed pump 15, a second closed pump 14, a third closed pump 13 and a makeup pump 11. The first closed pump 15 is connected to the working oil ports of the folding cylinder 112, the luffing cylinder 111 and the slewing motor 12 through the electromagnetic valve 49, the first closed pump 15 is connected to the working oil ports of the second lifting motor 101 and the second lifting motor 102 through the electromagnetic valve 410, and the first closed pump 15 is connected to the working oil port of the first lifting motor 103 through the electromagnetic valve 411. The second closed pump 14 is connected to the working oil ports of the folding cylinder 112, the luffing cylinder 111 and the slewing motor 12 through the electromagnetic valve 46, the second closed pump 14 is connected to the working oil ports of the second lifting motor 101 and the second lifting motor 102 through the electromagnetic valve 47, and the second closed pump 14 is connected to the working oil port of the first lifting motor through the electromagnetic valve 48. The third closed pump 13 is connected to the working oil ports of the folding cylinder 112, the luffing cylinder 111 and the slewing motor 12 through the electromagnetic valve 43, the third closed pump 13 is connected to the working oil ports of the second lifting motor 101 and the second lifting motor 102 through the electromagnetic valve 44, and the third closed pump 13 is connected to the working oil port of the first lifting motor through the electromagnetic valve 45.

[0054] In some embodiments, the electromagnetic valve 42 controls the brake of the lifting motor.

[0055] ​In some embodiments, the power unit further comprises a control pump 12 for providing stable control oil source for each control valve. The specific implementation can be achieved by using the prior art known to those skilled in the art, and thus will not be described here.

[0056] In some embodiments, the overflow valve 31 is an overflow valve at the outlet of the oil supplement pump 11 for limiting the maximum pressure of the oil supplement circuit; the overflow valve 32 is an overflow valve at the outlet of the control pump 12 for protecting the control oil circuit; the overflow valve 35 and the overflow valve 33 are low-pressure side B overflow valves of the second closed pump 14 and the third closed pump 13 for limiting the maximum pressure of the low-pressure side; the overflow valve 36 and the overflow valve 34 are high-pressure side overflow valves of the second closed pump 14 and the third closed pump 13 for limiting the maximum pressure of the high-pressure side; the overflow valve 37 is used for discharging the excess oil back to the oil tank when the folding arm oil cylinder 112 and the luffing oil cylinder 111 move.

[0057] In some embodiments, a cooler 7 is further arranged between the overflow valve 37 and the oil tank.

[0058] In some embodiments, the control unit comprises a one-way valve 21, a one-way valve 22, a one-way valve 23, a one-way valve 24, a one-way valve 25, a one-way valve 26, a one-way valve 27, a one-way valve 28, a one-way valve 29, a one-way valve 210, a one-way valve 211, a one-way valve 212, a one-way valve 213, and a one-way valve 214. The arrangement of the above-mentioned one-way valves is shown in Figure 1 .

[0059] In some embodiments of the present application, the execution unit comprises a first lifting motor 103 and a second lifting motor, the number of the second lifting motor is two, which are a second lifting motor 101 and a second lifting motor 102 shown in the figure, the power unit comprises a second closed pump 14; the second closed pump 14 is connected to the first lifting motor 103 through a first electromagnetic valve, and the second closed pump 14 further passes through a second electromagnetic valve to connect the second lifting motor 101 and the second lifting motor 102 after the first electromagnetic valve.

[0060] In some specific embodiments, the first electromagnetic valve can be electromagnetic valve 411, electromagnetic valve 48 or electromagnetic valve 45, and the second electromagnetic valve is electromagnetic valve 413. Specifically, the first closed pump 15 is connected to the working oil port of the first hoisting motor 103 through the electromagnetic valve 411, and the first closed pump 15 is connected to the working oil ports of the second hoisting motor 101 and the second hoisting motor 102 through the electromagnetic valve 411 and the electromagnetic valve 413 in turn; the second closed pump 14 is connected to the working oil port of the first hoisting motor 103 through the electromagnetic valve 48, and the second closed pump 14 is connected to the working oil ports of the second hoisting motor 101 and the second hoisting motor 102 through the electromagnetic valve 48 and the electromagnetic valve 413 in turn; the third closed pump 13 is connected to the working oil port of the first hoisting motor 103 through the electromagnetic valve 45, and the third closed pump 13 is connected to the working oil ports of the second hoisting motor 101 and the second hoisting motor 102 through the electromagnetic valve 45 and the electromagnetic valve 413 in turn, that is, the electromagnetic valve 413 connects the working oil circuits between the two second hoisting motors and the first hoisting motor 103.

[0061] In some embodiments of the present application, the accumulator 8 is a double-piston accumulator, and the air cavity of the accumulator 8 is connected to the nitrogen cylinder group 9.

[0062] In some specific embodiments, the high-pressure area A, the low-pressure area B, the air cavity C and the oil drain cavity D in the accumulator 8 are respectively connected to the high-pressure side A of the hoisting motor, the low-pressure side B, the nitrogen cylinder group 9 and the oil tank.

[0063] In some specific embodiments, the accumulator 8 is connected to the working oil ports of the second hoisting motor 101 and the second hoisting motor 102 through the electromagnetic valve 412; after the electromagnetic valve 413 is opened, the accumulator 8 can also be connected to the first hoisting motor 103.

[0064] In some specific embodiments, the third closed pump 13 is connected to the accumulator 8 through the electromagnetic valve 41 to adjust the pressures of the high-pressure area A and the low-pressure area B of the accumulator 8.

[0065] In some embodiments of the present application, the hydraulic system further comprises a motion reference unit (MRU) and a controller; the motion reference unit is connected to the controller, and the controller is respectively connected to the first hoisting motor 103 and the second closed pump 14, and is used for compensating the lifting motion of the hoisted load according to the wave motion.

[0066] In some specific embodiments, the controller can be a programmable logic controller, a distributed control system, an industrial computer, etc., and the present application does not make any limitation.

[0067] In some embodiments of the present application, the execution unit comprises a slewing motor 12, and the first closed pump 15 is connected to the slewing motor 12 and is used for driving the slewing action of the boom of the hoisting equipment.

[0068] In some embodiments of the present application, the oil cylinder comprises a luffing cylinder 111 or a folding cylinder 112; the luffing cylinder 111 is used to drive the luffing action of the crane boom; and the folding cylinder 112 is used to drive the folding and unfolding action of the crane boom.

[0069] In the hydraulic system in the embodiments of the present application, when the crane is working normally, the electromagnetic valve 413 is powered on, the oil supply pipeline of the second hoisting motor 101 and the oil supply pipeline of the second hoisting motor 102 are in communication with the oil supply pipeline of the first hoisting motor 103; the electromagnetic valve 42 is powered on to open the brake of the hoisting winch; the electromagnetic valve 44 and the electromagnetic valve 48 are powered on, and the third closed pump 13 and the second closed pump 14 are driven to drive the second hoisting motor 101, the second hoisting motor 102 and the first hoisting motor 103 through handle control; the electromagnetic valve 414 is powered on to open the brake of the slewing motor 12; the electromagnetic valve 49 is powered on, and the proportional valve 51, the proportional valve 52 and the proportional valve 53 are controlled through the handle, respectively, and the first closed pump 15 drives the luffing cylinder 111, the folding cylinder 112 and the slewing motor 12. When the first closed pump 15 drives the luffing cylinder 111 and the folding cylinder 112, because the area of the rod cavity of the cylinder is smaller than the area of the non-rod cavity, when the oil is supplied from the non-rod cavity and the oil is discharged from the rod cavity, the oil supply amount of the cylinder is greater than the oil discharge amount at this time, and the oil liquid is lost on the low pressure side of the closed loop, at this time, the oil supplement pump 11 supplements the low pressure side B of the first closed pump 15 through the one-way valve 25; when the oil is supplied to the rod cavity of the cylinder and the oil is discharged from the non-rod cavity, the oil supply amount of the cylinder is less than the oil discharge amount at this time, and the oil liquid is excessive on the non-rod cavity B side of the luffing cylinder 111 and the folding cylinder 112, at this time, the cylinder will be pressurized, and when the pressure reaches the set value of the overflow valve 37, the overflow valve 37 is opened, and the excess oil liquid is returned to the oil tank through overflow, so as to avoid that the pressure on the non-rod cavity side of the luffing cylinder 111 and the folding cylinder 112 is too high.

[0070] In the hydraulic system in the embodiment of the present application, when the passive wave compensation hoisting work is performed, the electromagnetic valve 413 is powered on, the oil supply pipelines of the second hoisting motor 101 and the second hoisting motor 102 are communicated with the oil supply pipeline of the first hoisting motor 103; the electromagnetic valve 42 is powered on to open the brake of the hoisting winch; the electromagnetic valve 41 is powered on, and the third closed pump 13 is controlled by the controller to adjust the accumulator 8, so that the pressures of the high-pressure area A and the low-pressure area B of the accumulator 8 are equal to the pressures of the A and B ports of the second hoisting motor 101, the second hoisting motor 102 and the first hoisting motor 103 respectively, and then the electromagnetic valve 412 is powered on to communicate the accumulator 8 with the hydraulic oil supply pipelines of the second hoisting motor 101, the second hoisting motor 102 and the first hoisting motor 103, at this time, the kinetic energy of the heave motion of the hoisted heavy object caused by the wave is absorbed by the accumulator 8, and the heave motion of the hoisted heavy object caused by the wave can be slowed down; during the passive compensation, the electromagnetic valve 47 and the electromagnetic valve 48 are powered on, the second hoisting motor 101, the second hoisting motor 102 and the first hoisting motor 103 are driven by the second closed pump 14 to ascend or descend the hoisted heavy object through the handle control; the electromagnetic valve 49 is powered on, the proportional valve 51, the proportional valve 52 and the proportional valve 53 are controlled by the handle respectively, and the first closed pump 15 drives the luffing cylinder 111, the folding arm cylinder 112 and the slewing motor 12.

[0071] In the hydraulic system in the embodiment of the present application, when the passive wave compensation hoisting work is performed, the electromagnetic valve 413 is powered on, the oil supply pipelines of the second hoisting motor 101 and the second hoisting motor 102 are communicated with the oil supply pipeline of the first hoisting motor 103; the electromagnetic valve 42 is powered on to open the brake of the hoisting winch; the electromagnetic valve 41 is powered on, and the third closed pump 13 is controlled by the controller to adjust the accumulator 8, so that the pressures of the high-pressure area A and the low-pressure area B of the accumulator 8 are equal to the pressures of the A and B ports of the second hoisting motor 101, the second hoisting motor 102 and the first hoisting motor 103 respectively, and then the electromagnetic valve 412 is powered on to communicate the accumulator 8 with the hydraulic oil supply pipelines of the second hoisting motor 101 and the second hoisting motor 102, the second hoisting motor 101 and the second hoisting motor 102 support the hoisted heavy object as the passive wave compensation motor; the electromagnetic valve 44 and the electromagnetic valve 48 are powered on, the controller receives the real-time motion parameters of the motion reference unit, and automatically adjusts the displacement of the second hoisting motor 101, the second hoisting motor 102 and the first hoisting motor 103 by controlling the third closed pump 13 and the second closed pump 14, so that the hoisted heavy object is lifted and lowered to compensate the real-time wave motion obtained by the motion reference unit. During the active wave compensation, the third closed pump 13 and the second closed pump 14 are driven by the handle operation superimposed command to lift and lower the hoisted heavy object of the hoisting motor; the electromagnetic valve 49 is powered on, the proportional valve 51, the proportional valve 52 and the proportional valve 53 are controlled by the handle respectively, and the first closed pump 15 drives the luffing cylinder 111, the folding arm cylinder 112 and the slewing motor 12.

[0072] In the description of the application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0073] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0074] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0075] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0076] It is to be understood that the terms "fixed" and "set" as used herein with respect to an element being "fixed" or "set" to another element means that the element can be directly on the other element or can have intervening elements present. When an element is considered to be "connected" to another element, it can be directly connected to the other element or can have intervening elements present. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar terms as used herein are for purposes of description and are not meant to be limiting.

[0077] The preferred embodiments of the present application have been described in detail above. It should be understood that modifications and variations can be resorted to without departing from the spirit of this application, as described above. Accordingly, it is contemplated that the application will encompass all modifications and variations as falling within the scope of the claims.

Claims

1. A hydraulic system for lifting equipment, characterized in that, include: Execution unit; A power unit, connected to the execution unit, is used to provide the driving medium; A control unit is disposed between the execution unit and the power unit for controlling the execution unit; The execution unit includes a hydraulic cylinder, the power unit includes a first closed-loop pump (15) and a replenishing pump (11), and the control unit includes a reversing valve. The reversing valve is located between the hydraulic cylinder and the first closed-loop pump (15) and is used to control the bidirectional movement of the piston rod of the hydraulic cylinder. The replenishing pump (11) is connected to the return oil pipeline between the hydraulic cylinder and the first closed-loop pump (15) and is used to replenish the first closed-loop pump (15) with oil when oil is discharged from the rod chamber of the hydraulic cylinder. An overflow valve is also provided on the return oil pipeline for overflow when oil is discharged from the rodless chamber of the hydraulic cylinder.

2. The hydraulic system according to claim 1, characterized in that, The execution unit includes a lifting motor, and the power unit includes a second closed pump (14), which is connected to the lifting motor and is used to connect to the winch of the lifting equipment to lift heavy objects.

3. The hydraulic system according to claim 2, characterized in that, The second closed-loop pump (14) is connected to the oil cylinder, and the first closed-loop pump (15) is connected to the lifting motor.

4. The hydraulic system according to claim 2, characterized in that, The execution unit includes a first lifting motor and a second lifting motor, and the power unit includes a second closed pump (14); the second closed pump (14) is connected to the first lifting motor via a first solenoid valve, and the second closed pump (14) is connected to the second lifting motor via a second solenoid valve after passing through the first solenoid valve.

5. The hydraulic system according to claim 4, characterized in that, The number of the second lifting motors is at least two.

6. The hydraulic system according to claim 4, characterized in that, The power unit includes a third closed-loop pump (13), and the control unit includes an accumulator (8); the third closed-loop pump (13) is connected to the accumulator (8), the first lifting motor and the second lifting motor respectively, and the accumulator (8) is connected to the second lifting motor.

7. The hydraulic system according to claim 6, characterized in that, The accumulator (8) is a double piston accumulator (8), and the gas chamber of the accumulator (8) is connected to a nitrogen cylinder group (9).

8. The hydraulic system according to claim 4, characterized in that, It also includes a motion reference unit and a controller; the motion reference unit is connected to the controller, and the controller is connected to the first lifting motor and the second closed pump (14) respectively, for compensating for the lifting motion of the suspended load according to the wave motion.

9. The hydraulic system according to claim 1, characterized in that, The execution unit includes a rotary motor (12), and the first closed pump (15) is connected to the rotary motor (12) to drive the rotation of the boom of the lifting equipment.

10. The hydraulic system according to claim 1, characterized in that, The hydraulic cylinder includes a luffing cylinder (111) or a folding boom cylinder (112); the luffing cylinder (111) is used to drive the pitching action of the boom of the lifting equipment; the folding boom cylinder (112) is used to drive the folding and unfolding action of the boom of the lifting equipment.

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