174 results about "Pilot-operated relief valve" patented technology

Disclosed is a pilot operated relief valve, in which a balance system is provided to offset a tank pressure exerted on a piston, so that a setting pressure of a pilot poppet is not changed even when the tank pressure is changed, and thus a function of the relief valve can be stably performed. The pilot operated relief valve is comprised of a sleeve, a main poppet provided to be movable in the sleeve, a seat provided in the sleeve, a housing connected to a rear end of the sleeve, a pilot poppet provided to be movable in the housing, a piston moved by a pilot signal pressure, and the balance system offsetting the tank pressure exerted on the piston.

The invention discloses a loading and unloading manipulator system of a broaching machine, which comprises an executing mechanism, a driving mechanism and a hydraulic control mechanism, wherein the driving mechanism comprises a waist seat, a bull gear, a pinion, a stepping motor, a waist revolving shaft, tapered roller bearings, a fixed upright and a rack cylinder; the executing mechanism comprises a rising oil cylinder, a rising oil cylinder piston, a rising oil cylinder piston rod, a rising guide rod, a sleeve, a lifting platform, a rolling bearing, a support plate, a support frame, a translation oil cylinder, a translation oil cylinder piston rod, a guide rod, a guide bushing, an annular sleeve and a manipulator; the manipulator comprises a paw and a telescopic oil cylinder; and the hydraulic control mechanism comprises a three-phase alternating current asynchronous motor, a hydraulic pump, an oil filter, an oil tank, a two-position two-way solenoid directional valve, a one-way valve, a pilot overflow valve, a three-position four-way solenoid directional valve, a speed regulating valve and a hydraulic cylinder. The system can guarantee the positioning control precision, and reduces impact and vibration to the greatest extent, so that the safety of the system is guaranteed.

Cartridge-style fluid control devices are provided that are static pressure independent and capable of repeatable, reliable, particulate insensitive performance in service conditions typical of downhole intervention environments.

A dual output shaft motor based shear plate synchronous control hydraulic system relates to a plate shear synchronous control hydraulic system. The dual output shaft motor based shear plate synchronous control hydraulic system comprises two shear cylinders, two stock stopping cylinders, three pressing cylinders and a shear cylinder synchronous control system, wherein the shear cylinder synchronous control system comprises an oil tank, two same hydraulic pumps, a dual output shaft motor for driving the two hydraulic pumps to rotate, and two first check valves; an oil outlet of each first one-way valve is connected with a first oil way, a second oil way and a third oil way respectively, the first oil way comprises a pilot operated compound relief valve and a two-position two-way electromagnetic valve, the second oil way comprises a sequence valve and a two-position four-way electromagnetic valve, the third oil way comprises a reducing valve, a second check valve and a first energy accumulator, the dual output shaft motor drives the two same hydraulic pumps to supply oil for the two same shear cylinders, so as to better guarantee the synchronous accuracy of the two shear cylinders, and the two shear cylinders are respectively connected with the first energy accumulator to maintain the pressure.

The invention discloses a system and method for controlling the temperature of hydraulic oil and belongs to the field of electronic control systems. The system comprises a temperature sensor, a controller, a first electromagnetic directional valve, an air cooler, an oil tank, a motor, a plunger variable pump and a pilot operated compound relief valve. The temperature sensor is arranged between a hydraulic system and the oil tank, and the controller is electrically connected with the temperature sensor. The plunger variable pump is in transmission connection with the motor, an oil inlet of the plunger variable pump communicates with the oil tank, the control end of the plunger variable pump is electrically connected with the controller, and an oil outlet of the plunger variable pump communicates with an oil inlet of the first electromagnetic directional valve and an oil inlet of the pilot operated compound relief valve at the same time. The control end of the first electromagnetic directional valve is electrically connected with the controller, a working oil opening of the first electromagnetic directional valve communicates with an oil inlet of the air cooler, an oil outlet of the air cooler communicates with the oil tank, and an oil outlet of the pilot operated compound relief valve communicates with the oil tank. The system and method for controlling the temperature of the hydraulic oil improve the control precision.

The invention relates to a well-head hydraulic signal generating device and an operating method thereof. The well-head hydraulic signal generating device is characterized by comprising a hydraulic oil source, power units, overflow valve banks and pressure test systems. The hydraulic oil source comprises an oil tank, wherein, the side wall of the oil tank is equipped with a temperature sensor and a liquid level sensor, the oil tank is internally equipped with an oil pipeline with a hydraulic oil filter, and the other end of the oil pipeline is connected with the power units; each power unit comprises a hydraulic pump driven by a variable frequency motor, wherein, an input terminal of the hydraulic pump is connected with the oil pipeline, an output terminal of the hydraulic pump is connected with a hydraulic signal pipeline, and the hydraulic signal pipeline is sequentially equipped with a check valve, a pipeline oil filter and a pipeline stop valve; and each overflow valve bank comprises an overflow pipeline, wherein, the overflow pipeline is connected on the hydraulic signal pipeline between the corresponding check valve and pipeline oil filter, an output terminal of the overflow pipeline is connected with a two-position two-way solenoid directional valve and a pilot overflow valve in parallel, an output terminal of the pilot overflow valve is connected with an H-type two-position four-way solenoid directional valve, and an output terminal of the two-position four-way solenoid directional valve is connected with two overflow valves in parallel.

A pilot operated pressure relief valve includes a valve body having a fluid inlet and a fluid outlet connected by a fluid passageway. A valve plug may be disposed within the fluid passageway, the valve plug cooperating with a valve seat to control fluid flow through the fluid passageway. An actuator may be connected to the valve plug, the regulator biasing the valve plug towards the valve seat. A pilot assembly may include a first pilot valve and a second pilot valve, wherein the pilot assembly directs fluid pressure upstream of the valve plug to one of the first and second pilot valves. When the upstream fluid pressure exceeds a predetermined level, the valve plug moves away from the valve seat allowing fluid to flow through the fluid passageway.

The invention discloses a hydraulic device which can carry out a pressure test on a packer on a well. The device comprises a pressure stabilizing loop, a pressure boosting loop and a reversing loop. The pressure stabilizing loop is connected with the reversing loop through the pressure boosting loop. The pressure stabilizing loop comprises an oil tank with an exhaust function, two low-pressure small-displacement fixed-displacement pumps connected in parallel and driven by a motor, a check valve, a pilot operated compound relief valve, a two-position two-way solenoid valve and a pilot operated type proportional overflow valve. The pressure boosting loop comprises a three-position four-way solenoid valve, two position sensors, a bidirectional pressure cylinder, four high-pressure check valves, a flowmeter, a pressure gauge and a pilot operated compound relief valve. The reversing loop comprises three two-position three-way solenoid valves, a pressure testing casing pipe, a packer center pipe, a packer sealing piece, three check valves, a deflation valve and a two-position two-way solenoid valve. The device can simulate the down-hole high-pressure environment, and detect the sealing performance of the packer.

The invention discloses a hydraulic system with a flow priority control function for small-volume blind cavity pressure control. An oil tank is connected to a low-pressure vane pump through an oil absorption filter; the low-pressure vane pump is connected to a high-pressure filter and a direct-acting safety valve respectively through a check valve; the high-pressure filter is connected to a flow priority valve; the flow priority valve is connected with a lubricating oil pipe of a hydro-viscous clutch through a flow valve; the flow priority valve is connected to a three-way proportional pressure reducing valve and a pilot overflow valve respectively; the three-way proportional pressure reducing valve, the direct-acting safety valve and the pilot overflow valve are all connected back to the oil tank; the outlet oil path of the three-way proportional pressure reducing valve is divided into two paths, one path is connected with one switch valve, and the other path is connected with two switch valves; and an energy accumulator is arranged on a pipeline. According to the hydraulic system disclosed by the invention, adjustable-flow supply for high-flow lubricating oil and constant-flow supply for low-flow control oil are realized; and meanwhile, the working point of the hydraulic system is changed through the switchover of the switch valves, and the stability of the small-volume blind cavity pressure control system is greatly improved under the condition of no influence on rapidity.

The invention provides a bending machine hydraulic synchronous system controlled by a flow distributing and collecting valve. The bending machine hydraulic synchronous system comprises an oil tank, a filter, a hydraulic pump, a motor, a one-way valve, a pilot-operated overflow valve, a two-position two-way solenoid directional valve, a three-position four-way solenoid directional valve, the flow distributing and collecting valve, a one-way speed regulating valve and hydraulic cylinders. When the hydraulic cylinders of the bending machine are in a pressing fast-feeding state or a pressing work-feeding state, after 2DT power-on pull-in, the left position of the three-position four-way solenoid directional valve is connected, under the action of the hydraulic pump, hydraulic oil enters the flow distributing and collecting valve through the one-way valve and the three-position four-way solenoid directional valve and enters rodless cavities of the hydraulic cylinders with flow equally divided. When the hydraulic cylinders are in a fast return stroke state, after 3DT power-on pull-in, the right position of the three-position four-way solenoid directional valve is connected, and the hydraulic oil in the rodless cavities enters the flow distributing and collecting valve and flows back to the oil tank through a flow collecting valve in an equal flow mode. Flow distributing and collecting functions are respectively achieved in the two directions of an oil path of the hydraulic system of the bending machine, so that synchronous operation of the two hydraulic cylinders in the work-feeding state or the return stroke state is effectively ensured, and synchronization precision is high.

The invention relates to a full-automatic plate shearing machine hydraulic system on the basis of PLC (Programmable Logic Controller) control and belongs to the field of plate shearing machine hydraulic systems. The full-automatic plate shearing machine hydraulic system mainly comprises the same first and second shearing cylinders, two same pressing cylinders, a hydraulic control system of the shearing cylinders and the pressing cylinders, and a PLC control system; the hydraulic control system of the shearing cylinders and the pressing cylinders comprises an oil tank, a hydraulic pump, a motor, a one-way valve, a first pressure gauge, a second pressure gauge, a pilot overflow valve, a two-position two-way electromagnetic valve, an energy accumulator, a pressure reducing valve, a travel switch, an overflow valve, a two-position four-way electromagnetic valve and a double hydraulic control one-way valve. According to the invention, the PLC control system is adopted to implement accurate control of the system; the full-automatic plate shearing machine hydraulic system is provided with the non-contact travel switch accurately controlled by the PLC control system, so that a sheet metal is more accurately positioned and quality of the sheared sheet metal is higher.

The invention discloses a hydraulic control valve unit for a rotating-vane type steering engine, belonging to the field of hydraulic control valve units. The hydraulic control valve unit comprises an electromagnetic reversing vale, a shuttle valve, a pilot-operated relief valve, a first cartridge valve, a second cartridge valve, a third cartridge valve, a fourth cartridge valve, a fifth cartridge valve, a sixth cartridge valve and a seventh cartridge valve; an oil inlet of the hydraulic control valve unit is communicated with a first oil inlet of the seventh cartridge valve and a first oil inlet of the electromagnetic reversing vale; a second oil inlet of the seventh cartridge valve is communicated with the oil outlet of the hydraulic control valve unit; an oil control port of the seventh cartridge valve is communicated with an oil inlet and an oil outlet of the pilot-operated relief valve; and the oil outlet of the pilot-operated relief valve is communicated with the oil outlet of the hydraulic control valve unit. The heating of a hydraulic system is reduced, thus the size of an oil tank of a hydraulic pump station is reduced, and the space in a ship is saved.

The invention discloses a liquid viscosity transmission tester with a hydraulic load device. The liquid viscosity transmission tester with the hydraulic load device comprises an oil supplying system and a simulation load loading system; an oil supplying system loop is connected with an oil supplying oil path coarse filter, a gear oil pump, an overflow valve, a speed regulating valve, a cooler, a liquid viscosity host, a flowmeter and an oil tank in sequence by a hydraulic pipeline. According to the simulation load loading system, a vane pump is adopted to replace the load device to load; the liquid viscosity host drives the load vane pump to work by the connection of a coupler; a simulation load loading system loop is connected with a load oil path coarse filter, the vane pump, a pilot operated compound relief valve and the oil tank in sequence by a hydraulic pipeline. The liquid viscosity transmission tester with the hydraulic load device is suitable for the test research of a liquid viscosity transmission technology, the system is greatly simplified while the basic demands of the test are met, so the system structure is deeply optimized and the design cost and the manufacturing cost are saved; the load loading system is closer to an actual working condition, so the system is more practical and reliable and has broad use value.

The invention discloses a hydraulic system of a buffering cylinder of a forging manipulator. The hydraulic system comprises an oil source oil supply opening, a proportional direction valve, an overflow valve, a one-way valve, the buffering cylinder, a pilot overflow valve, an electromagnetic direction valve, an oil source oil return opening, a displacement sensor, a displacement set signal, a subtractor and a PID (proportion integration differentiation) controller. A combined type multi-cavity structure of the buffering cylinder of the forging manipulator is utilized, a passive buffering system with the pilot overflow valve and an active displacement closed-loop control system with the proportional direction valve are integrated on the buffering cylinder, a passive buffering function of a clamp of the manipulator can be realized, and furthermore, a required displacement closed-loop control function of the buffering system of the forging manipulator is also realized. The hydraulic system has the advantages of simplicity in control and multiple functions. By a multi-cavity buffering mode of the buffering cylinder of the system, higher buffering force can be provided by the buffering cylinder with the same diameter. Besides, because proportional control elements are fewer, the reliability of the system is high.

Embodiments of the invention provide a relief valve body arranged for connecting to a pressure vessel. The relief valve body includes an inlet configured to connect to a pressure vessel and an integrated nozzle downstream from the inlet and extending along an axis. The integrated nozzle includes a nozzle exterior surface, a nozzle bulb, and a valve seat and defines a nozzle expansion region. The relief valve body further includes a redirecting pallet, a valve interior surface having at least one ramped portion downstream from the integrated nozzle and redirecting pallet, and an outlet downstream from the at least one ramped portion.

The invention discloses a wind turbine brake system, which comprises an oil supply system, an accumulator, a solenoid directional valve and at least one group of symmetrically arranged hydraulic cylinders, wherein two hydraulic cylinders are arranged in one group. An output end of the oil supply system is connected with an input end of a check valve; an output end of the check valve is divided into three paths, wherein the first path is connected with the accumulator, the second path is connected with a rod cavity of the hydraulic cylinder and the third path is connected with the solenoid directional valve; and a motor in the oil supply system drives a pump through a first electromagnetic clutch. The wind turbine brake system also comprises a second electromagnetic clutch for connecting the pump and a high-speed shaft of a gearbox of a wind turbine transmission system; and an output end of the pump is connected with an oil tank through a pilot overflow valve. When the wind turbine brake system normally stops, the first electromagnetic clutch is controlled to be disconnected with power and the second electromagnetic clutch is controlled to be connected with power, so that the motor is disconnected with the pump, the pump is connected with the gearbox, the wind turbine is braked by consuming kinetic energy during rotation of an impeller, and excessive wear of a brake sheet is avoided.

The invention provides a pressure maintaining and speed stabilizing hydraulic system of a hydraulic machine. The pressure maintaining and speed stabilizing hydraulic system comprises an oil tank, a filter, a hydraulic pump, a motor, a one-way valve, a pilot operated compound relief valve, a two-position two-way electromagnetic directional valve, a three-position four-way electromagnetic directional valve, a double-hydraulic-control one-way valve and a one-way speed regulating valve. When the hydraulic machine works in the feeding working station, the left position of the three-position four-way electromagnetic directional valve is connected; oil liquid enters a first hydraulic cylinder rodless cavity through the one-way valve, the three-position four-way electromagnetic directional valve and the left one-way valve in the double-hydraulic-control one-way valve under the effect of the hydraulic pump; oil liquid in a rod cavity enters a second hydraulic cylinder rodless cavity through a pipe and returns to the oil tank through a speed regulating valve body in the one-way speed regulating valve, and a valve opening of the speed regulating valve body is set to be capable of achieving the stability of the motion speed of the hydraulic machine during feeding. The hydraulic system of the hydraulic machine has the advantages of being remarkable in pressure maintaining effect in the feeding working condition, stable in running speed, rapid in returning and high in efficiency.

The invention discloses a two-stage bi-directional high-precision hydraulic synchronous control system and relates to the field of multi-executing-mechanism synchronous control. The two-stage bi-directional high-precision hydraulic synchronous control system is mainly composed of a hydraulic synchronous motor, a proportional servo valve, a hydraulic cylinder, a check valve and pilot operated compound relief valves. The hydraulic synchronous motor is used for conducting a first stage of distribution on oil entering the hydraulic cylinder on a main oil line, then an oil port A and an oil port B of the proportional servo valve are connected with a rodless cavity and a rod cavity of the hydraulic cylinder respectively, and secondary adjusting is conducted on distributed flow of the hydraulic synchronous motor. In order to eliminate flow coupling between two groups of hydraulic synchronous motors, decoupling between inlet flow and outlet flow of the oil cylinder is achieved by connecting a remote control port of one group of pilot operated compound relief valve with an oil tank. Due to the fact that the hydraulic synchronous motor and the proportional servo valve are matched to adjust flow of a hydraulic cylinder oil inlet, a severe consequence caused by accidental damage or power down of the proportional servo valve is avoided, the reliability of the system is improved, and bi-directional high-precision synchronization of the system is guaranteed.

The invention discloses a heavy long rod hoisting mechanism hydraulic system. The hydraulic system is provided with a double-linkage fixed displacement vane pump set used for supplying oil and comprises a speed control loop and a position control loop. The speed control loop is connected with an upper cavity and a lower cavity of a three-cavity hydraulic cylinder through a large pump of the double-linkage fixed displacement vane pump set, the large pump is connected with a check valve and an oil sucking filter, and the oil sucking filter is connected with a pilot overflow valve and a proportional servo valve. Non-balanced disturbance can be effectively inhibited in the hoisting process of a heavy long rod, stability of a servo system is guaranteed, and accurate balance control and positioning control are achieved.

The invention discloses an ultrahigh pressure pilot operated relief valve, consisting of a main valve and a pilot valve. The pilot valve is composed of a pressure-regulating hand wheel, a regulating bolt, a pilot valve pressure-regulating spring, a pilot valve element, a high-strength separating type valve seat and a plug. The separating type valve seat is provided with a center hole and two conical ends, and is tightly pressed to the pilot valve body by the plug that is in threaded connection with the pilot valve body, and the plug is provided with radial and axial holes. The pilot valve element and the high-strength separating type valve seat are matched to form rigidity seal. The ultrahigh pressure pilot operated relief valve adopts the separating valve seat, is simple in structure, convenient to install, maintain and replace, overcomes the problems that the common pilot operated relief valve is poor in reliability and short in service life when being used in an ultrahigh pressure system.

The invention discloses a hydraulic flow distributing system for distributing the pressure proportion randomly. The hydraulic flow distributing system comprises an oil tank, a split-flow valve, a metering pump, a motor and a pressure regulating unit. The oil tank, the input end of the split-flow valve and the motor are connected with the metering pump, and a coupler is connected between the motorand the metering pump. The two output ends of the split-flow valve are connected with a pilot type overflow valve and a reversing valve correspondingly. The pressure regulating unit comprises a rack,a lead screw and a pilot type overflow valve. The two pilot type overflow valves are symmetrically arranged on the two sides of the rack, and the two ends of the lead screw are connected with the pilot type overflow valve correspondingly. The lead screw comprises a screw rod and a nut spirally connected to the screw rod. According to the hydraulic flow distributing system, the ball screw is adopted as an actuating element, the pretightening force of springs of the two pilot type overflow valves is controlled by rotating the nut on the ball screw, then the pressure of the overflow valve is regulated to control the pressure of two branches, and finally distribution of any pressure proportion is achieved. The hydraulic flow distributing system is wide in application range and low in cost.

The invention discloses a PLC control system and method of a servo energy-saving control system of a ceramic press. A pressure \ adjusting end of a pilot overflow valve is communicated with an oil tank sequentially through a proportional overflow valve and a three-position four-way valve and is communicated with the oil tank through an overflow valve; a first position sensor and a second position sensor are arranged on a pressure die casting machine; and the first position sensor, the second position sensor, a contact detection sensor, a first motor, the proportional overflow valve, a two-position four-way valve and a three-position four-way valve are all electrically connected with a servo driver. The PLC control device enables the pressure die casing machine to achieve automatic adjusting of working pressure and flow according to the different technological stages, and aim that the amount of flow and pressure are provided according to the needed amount of flow and pressure; many resources can be saved, and the phenomenon that an original press oil pump runs at full speed all the time, and electric energy is wasted is completely avoided.

The invention provides a hydraulic system for a pile driving barge. The hydraulic system for the pile driving barge comprises a hydraulic pump oil supplying loop which consists of a constant-pressure variable pump and a control valve set of the constant-pressure variable pump, wherein an oil absorbing port of the constant-pressure variable pump communicates with an oil tank which is used for supplying oil; the hydraulic pump oil supplying loop further comprises at least two pressure and power combined control variable pumps which are interconnected in parallel; oil ports in oil draining pipelines of the pressure and power combined control variable pumps are connected with pressure buffering control valve sets; each pressure buffering control valve set comprises a first pilot overflowing valve, a first pressure reduction valve, a first fixed throttling port, a first adjustable throttling port, a first one-way valve and a first electromagnetic reversing valve. The hydraulic system for the pile driving barge can be started with no load, is stable to increase and release pressure, can be automatic to adjust matched power, and is constant in tension of a steel cable in releasing during barge moving. The hydraulic system for the pile driving barge has the advantages of being small in pressure impact, low in vibration and noise, obvious in energy saving effect, small in calorific value, and accurate to position in pile driving.

An apparatus is provided that quickly elevates and maintain a construction equipment engine coolant to operating temperature in order to lower the dwell time for the operator's cab to reach a comfortable temperature level during a period when the engine is in idle and main crane functions are not operated. The apparatus includes an auxiliary hydraulic circuit for rapidly bringing engine coolant temperature up to operating temperature. Engine coolant operating temperature is achieved by inducing a hydraulic load to the engine. By inducing a hydraulic load, a horsepower load is exerted on the engine causing the engine to generate heat sufficient to raise the engine coolant to operating temperature for heating the cabin. A pressure reducing relieving valve and a pilot operated relief valve result in precise hydraulic horsepower load to the construction equipment engine. Operation of the pilot operated relief valve also warms hydraulic fluid for a hydraulic reservoir.

The invention discloses a vertical hydraulic system for a waste transfer station transfer vehicle. The vertical type hydraulic system for the waste transfer station transfer vehicle is composed of an oil tank, a filter, a pilot type overflow valve, a hydraulic pump, an overturning frame lifting oil path, an overturning frame falling oil path, a sliding frame moving oil path and a container opening or closing oil path and a route switch. The overturning frame lifting oil path is composed of an O-type functional three-position four-way reserving valve II, a safety overflow valve I, a five-level single-action cylinder, a two-position two-way general reserving valve II and a one-way valve I. The overturning frame falling oil path is composed of an O-type three-position four-way reserving II, a two-position two-way reserving valve II, a two-way two-position reserving valve III, a speed regulation valve, a one-way valve II and a dual-action cylinder III. The sliding frame moving oil path is composed of a pilot type pressure reducing valve, a Y-type three-position four-way reserving valve, a two-position two-way general reserving valve I, an external control outward-discharge pilot operated check valve, a safety overflow valve and a dual-action cylinder II. The container opening or closing oil path is composed of a pilot type pressure reducing valve II, an O-type functional three-position four-way general reserving valve I, a throttle valve and a dual-action cylinder I.

Provided is a method of and valve assembly for dumping excess fluid during retraction of a cylinder actuator. The method includes pumping fluid with a pump from a piston side of the cylinder to a rod side of the cylinder; opening a first check valve with relatively high pressure fluid from a downstream side of the pump to allow flow into the rod side of the cylinder; and opening an extend relief valve via a first spool with fluid from the downstream side of the pump to allow excess fluid at an upstream side of the pump to return to a reservoir at relatively low pressure.

The invention provides an electric coupler pulling-out force testing device and a method thereof. The electric coupler pulling-out force testing device is composed of a hydraulic system, a water pressure control system and a measurement and control system. The hydraulic system is composed of a gear pump, solenoid directional valves, a pilot overflow valve, an energy accumulator, a proportional throttle valve, an oil cylinder, an air cooler, filters and a pressure gage. The water pressure control system is composed of a pressure testing pump, a variable frequency motor, stop valves, energy accumulators, pressure gages, pressure sensors, a pressure barrel, a motor frequency converter, a PLC and a touch screen. The measurement and control system is composed of pressure sensors, a displacement sensor, an industrial personal computer, a data acquisition card, a relay module and an isolation module. According to the testing device, a water pressure environment with the pressure ranging from 0 MPa to 6 MPa is built for electric coupler pulling-out, it is guaranteed that the pressure fluctuation range is within 5% in the electric coupler pulling-out process, the pulling-out speed within the range from 0 m / s to 1 m / s and the maximum pulling-out force not smaller than 5,000 N are provided, and the pulling-out force at the moment of electric coupler disengagement is calculated out.

The invention discloses an independent pilot-operated type flow control valve, comprising a main valve. An actuator part is arranged on the main valve and consists of a hydraulic control element manifold block and a pilot-operated type overflow valve, wherein the hydraulic control element manifold block is fixed on an upper valve cover of the main valve, the pilot-operated type overflow valve is fixed on the hydraulic control element manifold block which is connected with an inlet front pipeline of the valve through a medium collecting inlet pipe fitting assembly, and the pilot-operated type overflow valve is connected with an outlet rear pipeline of the valve through an outlet pipe connector assembly. The hydraulic actuating element of the control valve is composed of the manifold block and the independent pilot-operated type overflow valve which are in linkage with each other, and the action execution and the adjustment control are stable and agile. A piston type valve core resists high pressure and has a good sealing property and a long service life. The independent pilot-operated type flow control valve can be automatically closed in a low pressure state, has a check function when applied to an oil extraction system, has a fireproofing and obstruction functions when applied to an oil transmission system of an oil depot, and effectively overcomes the defects in the prior art.