7710results about "Servomotors" patented technology

The invention discloses a deep sea underwater electro-hydraulic actuator (EHA) and a control system thereof. The system provides power through the power source module, balance of system oil pressure and pressure of external seawater is controlled through the pressure compensation module, oil circulation and oil pressure control are conducted through the integrated valve set module, a control instruction of the control module is executed through the execution mechanism module, and the control module conducts cooperative control over the whole system. According to the control system, the unbalanced pressure between the system and the deep sea high-water-pressure environment is compensated through the pressure compensator so as to reduce the influence of the deep sea high-water-pressure environment, meanwhile, the pressure compensator serves as an oil tank to supply oil, miniaturization of the system is achieved, and the reliability of the system during underwater work is improved; according to the deep-sea underwater electro-hydraulic actuator, the mounting positions and internal flow channels of all elements of the integrated valve bank are optimized, the pressure loss of fluid in the flow channels is reduced, and the energy utilization efficiency of the deep-sea underwater electro-hydraulic actuator is improved; the asymmetric hydraulic cylinder can operate in four working conditions of deep sea, and underwater high-precision movement can be completed.

The invention discloses a seeding monomer seeding depth and suppression control method and a control device thereof.The method comprises the steps that control parameter data are obtained, and the control parameter data comprise a seeding mode and / or suppression / pressing parameters; determining an operation mode based on the control parameter data; when the operation mode is a downward pressing mode and a pressing mode, a pressing hydraulic cylinder and a downward pressing hydraulic cylinder are adjusted to stretch and retract in real time based on data collected by a pressing force sensor and data collected by a downward pressing force sensor, so that target pressing force and target downward pressing force are kept; and when the operation mode is a pressing / pressing cooperation mode, data collected by the pressing force sensor and the pressing force sensor are obtained at the same time, and the pressing hydraulic cylinder and the pressing hydraulic cylinder stretch out and draw back at the same time, so that the target pressing force and the target pressing force are kept. According to the scheme, on-demand switching of the pressing mode, the pressing mode and the pressing / pressing cooperation mode can be achieved, and compared with a fixed mode in the prior art, higher adaptability and flexibility are achieved.

The invention relates to a split type electro-hydraulic direct-driven non-retractable fin stabilizer hydraulic system which comprises a hydraulic unit and an actuating mechanism which are independently arranged, and the actuating mechanism comprises fin rotating oil cylinders which are symmetrically arranged; a bidirectional hydraulic pump driven by a servo motor forms a closed fin rotating loop; the bidirectional hydraulic pump driven by the servo motor, the hydraulic unit and the actuating mechanism form an electro-hydraulic direct-drive fin stabilizer device; the control loop is composed of a gyroscope, a controller and an executing mechanism, and the gyroscope detects the rolling angular velocity of the ship and generates a fin rotating instruction signal; the controller compares the instruction signal with the fin angle feedback signal and outputs a servo motor rotating speed instruction; the servo driver controls the servo motor to rotate forwards and backwards, the bidirectional hydraulic pump is driven to adjust the displacement of the fin rotating oil cylinder, and therefore the fin is driven to rotate. A valve control or pump control type hydraulic system adopted by a traditional fin stabilizer is replaced, integrated optimization, light weight, high efficiency, high reliability and low noise of the fin stabilizer hydraulic system are achieved, and the occupied space of equipment is reduced.

The invention discloses a hydraulic loading system for a semi-physical simulation platform of an excavator. The hydraulic loading system comprises a loading pump set, a confluence switching valve set, a movable arm linkage loading valve set, a bucket rod linkage loading valve set, a bucket linkage loading valve set, a rotation linkage loading valve set, a flow detection assembly, a pressure detection assembly, a multi-way valve and an excavator power unit. Oil inlet ports of all the multi-way valves provide oil inlet through an excavator power unit, flow of oil return ports of a movable arm link, a bucket rod link and a bucket link provides an oil source through a loading pump set, loading valve sets simulate loading load pressure, and the oil return amount and the oil return back pressure are controlled through speed regulating valves of all the loading valve sets. And the rotary unit controls the oil return quantity and simulates the rotary load through a rotary loading valve group. Multi-pump-set loading is adopted, the loading flow range is large, universality is high, an execution oil cylinder and an execution motor do not need to be installed and replaced, and operability is high; the oil inlet and return flow and pressure of the movable arm unit, the bucket rod unit and the bucket unit are independently loaded and are not limited by the area ratio of two cavities of an oil cylinder.

A header of a harvester includes a header segment, a center section, an actuator coupling the header segment to the center section, and a controller. The header segment includes a cutter bar configured to cut crops and the header segment includes a first portion of a conveyor assembly. The center section includes a second portion of the conveyor assembly, in which the center section is configured to receive crops from the header segment via the first portion of the conveyor assembly, and the second portion of the conveyor assembly is configured to transport the received crops to a crop processing system of the harvester. The controller is configured to receive a signal indicative of a target position of the header segment and the controller is configured to control the actuator to adjust the header segment to the target position.

A modulator (20) for generating a pressure change in response to a control pressure has a first venting path (25) and a second venting path (26) for venting a pneumatic load (11). The modulator (20) has a relay valve (30) that is configured to vent the pneumatic load (11) via the first venting path (25). The modulator (20) has a vent valve (40) that is configured to vent the pneumatic load (11) via the second venting path (26).

To avoid a large size of a direction change-over valve and enable accurate supply flow control when providing a flow control valve at an upstream side of the direction change-over valve to change the relationship between supply flow rate and discharge flow rate for a hydraulic actuator. The configuration is to control a supply flow rate to a stick cylinder based on an opening area of the stick's direction change-over valve and stick's flow control valve, calculate a target opening area of the stick's flow control valve based on a target supply flow rate from hydraulic pumps A, B to the stick cylinder, the opening area of the stick's direction change-over valve, and a target differential pressure between hydraulic pump A and a load pressure of stick cylinder, and control the stick's flow control valve so as to keep the target opening area calculated.

The invention designs a linear heave compensation device based on a composite cylinder, belongs to the technical field of ocean engineering equipment, adopts a heave compensation scheme of a double-composite-cylinder structure comprising a heave compensation execution cylinder and an integrated control cylinder, and is provided with a plurality of functional cavities; the working gas cylinder group is communicated with a rod cavity of the heave compensation execution cylinder through the gas-liquid converter to provide passive compensation force for the heave compensation execution cylinder; oil is alternately supplied to inner cavities of the two composite cylinders in a control mode of direct driving of the two-way variable pump, and active compensation force is provided for the heave compensation execution cylinder; for an underwater high-pressure environment, deepwater pressure acts on a piston rod of the integrated control cylinder and a piston rod of the heave compensation execution cylinder at the same time, and the water depth compensation function is achieved through offset of internal pressure of the double cylinders. Multiple functions such as passive compensation, active compensation and water depth compensation are achieved, multiple working condition operations such as water, splash zone passing and landing can be continuously completed, the two-way variable pump is adopted to directly drive the compensation execution cylinder, the response speed and the control precision are improved, and the beneficial effects of being low in energy consumption, compact in structure, integrated in multiple functions and the like are achieved.

The invention relates to the technical field of hydraulic servo control systems, and discloses a high-precision hydraulic servo control system and a fault diagnosis method thereof.The hydraulic servo control system comprises a system control module, a hydraulic execution module, a data feedback module, an automatic compensation module and a feedback control module; the system control module is used for receiving and processing an input signal and outputting a control instruction; the hydraulic execution module is used for generating a corresponding hydraulic action according to the control instruction; the data feedback module is used for detecting the actual position and pressure of the hydraulic execution module and transmitting a feedback signal to the automatic compensation module; the automatic compensation module is used for eliminating system errors through a compensation algorithm; the feedback control module is used for comparing the difference between the system output and a set target, generating a deviation signal, and adjusting the input of the system by using the signal, so that the system output is closer to the set target; through the system, the control precision and stability of the hydraulic servo control system can be improved.

The invention discloses a control method of a flap unloading platform, which is applied to a hydraulic control system of the flap unloading platform, and comprises the following steps: acquiring a starting signal, and enabling a power driving branch based on the starting signal; the system pressure of a hydraulic control system of the turning plate unloading platform is controlled by the power driving branch to be gradually increased; in response to the fact that the system pressure is equal to the preset value, the power-on state of the main electromagnetic valve is changed, the first proportional throttle valve and the second proportional throttle valve are adjusted based on the second working state of the main electromagnetic valve, the first lifting oil cylinder and the second lifting oil cylinder are controlled to act, and the turning plate unloading platform is driven to rotate; and in response to rotation of the flap unloading platform to the preset angle, the power-on state of the main electromagnetic valve is changed, so that the flap unloading platform is controlled to stop rotating based on the first working state of the main electromagnetic valve. By controlling the first proportional throttle valve and the second proportional throttle valve which are independent, independent control over the first lifting oil cylinder and the second lifting oil cylinder is achieved so that synchronous action can be achieved.

A linear actuator system includes a linear actuator and an integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with two fluid drivers, each fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes the pump in a normal mode of operation in which the prime movers are independently driven and switches to a fail-safe mode of operation in which only one prime mover is operated.

A hydraulic circuit is disclosed which includes one or more i) linear; or ii) rotary hydraulic actuator, wherein total number of cylinder chambers is N, M pressure rails, a valve arrangement, including M hydraulic rail ports each coupled to a pressure rail, N hydraulic chamber ports each coupled to a chamber of one or more actuators, N proportional valves each corresponding to one of the N hydraulic chamber ports, X sets of on-off valves and check valves coupling two or more hydraulic rail ports to each of supply sides of each of the N proportional valves, and Y sets of on-off valves and check valves coupling two or more hydraulic rail ports to each of return sides of each of the N proportional valves, and a controller configured to in real-time operate the N proportional valves and the associated on-off valves to achieve one or more desired functional parameters.

The invention discloses an active and passive combined electro-hydraulic actuator and a method thereof, and belongs to the field of hydraulic control. The electro-hydraulic actuator comprises a hydraulic source, a hydraulic oil cylinder, a control system, an oil liquid outlet, a low-rigidity energy accumulator, a high-rigidity energy accumulator and a high-pressure energy accumulator, the hydraulic oil cylinder is an asymmetric hydraulic oil cylinder, the control system comprises a rotary servo valve and a rapid rotary switching valve, the rotary servo valve has a three-position four-way function, and the rapid rotary switching valve has a three-position four-way function. An oil outlet of the hydraulic cylinder is respectively connected with the oil liquid outlet, the low-rigidity energy accumulator, the high-rigidity energy accumulator and the high-pressure energy accumulator through a quick rotating switching valve. Active control and passive mode switching of the hydraulic oil cylinder are achieved by rotating the servo valve; connection switching among the energy accumulators is achieved by rapidly rotating the switching valve, so that the electro-hydraulic actuator is in different passive modes. The actuator system is high in response speed, the actuator can complete active and passive mode switching under the same stride, and the energy utilization rate is improved to the maximum extent.

The invention relates to the technical field of hydraulic transmission, and provides a variable-speed variable-displacement electro-hydraulic power source control method and a hydraulic system.The method comprises the specific steps that the system pressure and the system flow at the current moment are obtained; the initial rotating speed of the servo motor at the current moment is detected, and the initial displacement of the two-way variable pump at the current moment is obtained; a genetic algorithm is used for obtaining the optimal displacement of the two-way variable pump and the optimal rotating speed of the servo motor; the servo motor is adjusted according to the optimal rotating speed of the servo motor, so that the two-way variable pump works at the combination point of the optimal displacement and the optimal rotating speed; and during the working period of the two-way variable pump, the steps are cyclically executed to realize real-time regulation and control of the electro-hydraulic power source. According to the method, the efficiency model and the dynamic response model of the electro-hydraulic power source are established, the intelligent optimization algorithm is used for conducting multi-target dynamic optimization on the efficiency and the response time of the electro-hydraulic power source, the rotating speed of the servo motor and the displacement of the two-way variable pump are controlled in a coordinated mode, and the electro-hydraulic power source works in a high-efficiency and high-response area.

A hydraulic vibration generation device or hydraulic motor is provided. The device includes a manifold having an inner volume with a pressure chamber extending into the inner volume, a fluid inlet orifice and a fluid outlet orifice. The device further includes a vibration generating member having a grooved drive and an off-center weight and retaining plates. The inner volume receives the vibration generating member within the inner volume. The vibration generating member rotates and generates vibration in response to hydraulic fluid flowing into the manifold through the inlet orifice and directed through the pressure chamber, relieves pressure upon exiting the pressure chamber and out of the manifold through the outlet orifice. Also provided a hydraulic motor with a same manifold and pressure chamber, but with a power generating member having the same groove drive without and off-center weight. Rotation of the power generating member generates power.

The invention discloses a double-variable power source hydraulic system of a movable arm of an electric loader and a control method, and belongs to the technical field of energy conservation of electric engineering machinery. The hydraulic system is structurally characterized in that a permanent magnet synchronous servo motor and an electro-hydraulic proportional variable device form a double-variable power source direct drive arm hydraulic cylinder; the one-way valve achieves oil cylinder and motor oil supplementing and flow reappearing functions according to the working condition of a hydraulic cylinder, the direct-acting overflow valve achieves overflow protection of a hydraulic system, and the two-position two-way electromagnetic directional valve achieves the pressure maintaining function of the hydraulic cylinder. According to the control method of the hydraulic system configuration, an upper computer outputs a target instruction to a double-variable parameter optimization controller, then the double-variable parameter optimization controller outputs an optimization rotating speed or displacement signal to a motor pump set, and a pump outlet pressure sensor feeds back a pressure signal to achieve a pressure closed loop. The energy recovery function can be effectively achieved in the aspect of configuration, the energy efficiency characteristic of a power source can be greatly improved in the aspect of a control method, and the endurance time of the electric loader is effectively prolonged.

The invention relates to the technical field of hydraulic control, and provides a pump-controlled semi-active ship heave compensation hydraulic system and a control method thereof.The system comprises an active compensation hydraulic module, a passive compensation hydraulic module, a sensor module, a controller and a motion sensor; the passive compensation hydraulic module comprises a nitrogen cylinder unit, an energy accumulator unit, a gas-liquid converter, a seventh electromagnetic directional valve, a fourth electromagnetic directional valve and a passive compensation asymmetric hydraulic cylinder; the active compensation hydraulic module comprises a third energy accumulator, a servo motor, a two-way quantitative hydraulic pump, a first one-way valve, a second one-way valve, an active compensation asymmetric hydraulic cylinder, a first electromagnetic reversing valve, a second electromagnetic reversing valve and a third electromagnetic reversing valve. According to the invention, passive compensation and active compensation are fused, so that the compensation precision and efficiency are greatly improved; and an electro-hydraulic servo pump control mode is adopted, so that the advantage of high control precision of a valve control mode is reserved, and the stability is also improved.

The invention discloses a control method and device of a hydraulic synchronous lifting device, a computer program and a storage medium, belongs to the technical field of ship manufacturing, and particularly relates to a control method of a hydraulic synchronous lifting device for ship assembly. In order to solve the problems of low synchronization precision, slow dynamic response, insufficient error compensation, poor environmental adaptability and the like of the existing control method of the hydraulic synchronous lifting device, the invention provides the control method of the hydraulic synchronous lifting device, which comprises the following steps of: acquiring a target height, a maximum inclination angle, a maximum deviation and a preset proportional valve opening; the actual heights of the four main jacking oil cylinders are obtained in real time, the average value and the inclination angle are calculated, whether the target height is reached or the maximum inclination angle is exceeded is judged, if not, the deviation of each oil cylinder is calculated, and the opening degree of the corresponding proportional valve is adjusted when the deviation is exceeded, and synchronous lifting is ensured. The device is suitable for the fields of ship building and maintenance, in-place and leveling of bridge precast beam bodies and extremely high requirements for lifting precision and safety.

The pneumatic pulse valve body assembly is arranged between an air source body and an air using assembly of the massage system and comprises a first valve body and a second valve body which are arranged in a combined mode and are different in switching frequency, and the switching frequency of the first valve body is larger than that of the second valve body; the number of the first valve body is at least one, the first valve body comprises a first air inlet end and a first air outlet end, and the first air inlet end is communicated with the air source body; the second valve body comprises a second air inlet end and an air inflation end, the air inflation end is communicated with the air using assembly, and the second air inlet end is communicated with the first exhaust end; when the air source body inflates the air using assembly, the first valve body executes high-frequency and rapid opening and closing actions to control the state of air flow introduced into the second valve body, the air flow is controlled and then inflates the air using assembly in a pulsating mode through the second valve body, an air bag is jacked up step by step, and the air bag is inflated into the air using assembly in a pulsating mode. Therefore, richer massage experience feeling is brought to passengers.

A hydraulic vibration generation device or hydraulic motor is provided. The device includes a manifold having an inner volume with a pressure chamber formed in the inner volume, a fluid inlet orifice and a fluid outlet orifice. The device further includes a vibration generating member having a grooved drive and an off-center weight and retaining plates. The inner volume receives the vibration generating member within it. The vibration generating member rotates and generates vibration in response to hydraulic fluid flowing into the manifold through the inlet orifice and directed through the pressure chamber, relieves pressure upon exiting the pressure chamber into a pressure relief channel and out of the manifold through the outlet orifice. Also provided a hydraulic motor with a same manifold and pressure chamber, but with a power generating member having the same groove drive without an off-center weight. Rotation of the power generating member generates power.

The invention provides an underground coal mine air and water pumping switching electro-hydraulic control system and method, the electro-hydraulic control system comprises an air supply control module, a water supply control module, a negative pressure control module and an oil supply module, and the method adopts a remote control system to control the underground coal mine air and water pumping switching electro-hydraulic control system. According to the underground coal mine air and water pumping switching electro-hydraulic control system, air and water pumping electric control rapid opening and closing and rapid switching of different functions are achieved, the automation degree of air and water pumping switching is improved, and the air and water pumping switching time is shortened; and meanwhile, when dangerous working conditions that gas accumulation exceeds the limit due to hole blocking behind the drill hole or carbon monoxide gas appears in the drill hole and the like, rapid and automatic response processing can be achieved. The air and water pumping conversion efficiency is improved, the labor intensity of workers is relieved, and key technical support is provided for coal mine underground automatic drilling whole-process operation.

The invention provides a hydraulic control system of an asymmetric hydraulic cylinder, and relates to the technical field of hydraulic control, the hydraulic control system comprises a bidirectional hydraulic pump, a hydraulic motor and an energy accumulator, the bidirectional hydraulic pump is in transmission connection with a first servo motor, and a first oil port and a second oil port of the bidirectional hydraulic pump are connected with a rod cavity and a rodless cavity through a first oil way and a second oil way respectively; a first one-way valve is arranged between the second oil port and the rodless cavity; the hydraulic motor is in transmission connection with the generator which is connected with the electric energy storage unit. The hydraulic motor is connected with the first one-way valve in parallel; the energy accumulator communicates with the first oil way and the second oil way through a second one-way valve and a third one-way valve correspondingly. Four-quadrant seamless switching can be achieved, the structure is simpler, the complexity of a pipeline in a hydraulic system is remarkably reduced, energy collection can be conducted on oil discharged by a rodless cavity, and energy consumption is further reduced.

The invention discloses a deep sea underwater integrated electro-hydraulic actuator system adopting pump and valve combination. The deep sea underwater integrated electro-hydraulic actuator system comprises a hydraulic cylinder, a pump control assembly and a valve control assembly. The pump control assembly comprises a metering pump, a first switch valve and a second switch valve; the valve control assembly comprises a large-flow proportional valve, a small-flow proportional valve, a deep sea compensation energy accumulator and a third switch valve. The metering pump, the first switch valve and a rod cavity of the hydraulic cylinder are sequentially connected through a pipeline, the metering pump, the second switch valve and a rodless cavity of the hydraulic cylinder are sequentially connected through a pipeline, the metering pump, the third switch valve and the deep sea compensation energy accumulator are sequentially connected through a pipeline, and the rodless cavity of the hydraulic cylinder is connected with the large-flow proportional valve and the small-flow proportional valve through pipelines. Two control modes of the actuator can be completed, large-flow control is achieved through the pump control assembly, high efficiency and energy conservation are achieved, flow needed by maintenance is supplied to a rodless cavity of the actuator through the valve control assembly via the large-flow proportional valve and the small-flow proportional valve, and posture keeping and emergency action are achieved.

The invention discloses an opening and closing hydraulic system and a control method. The system comprises an oil cylinder, an oil tank, an energy accumulator, a pump set, a detection module, an opening and closing loop and an adjusting loop. The connecting end of the opening and closing loop is connected with a rod cavity and a rodless cavity of the oil cylinder, and an oil inlet of the opening and closing loop is in redundant connection with the energy accumulator and the pump set. The detection module is used for monitoring the slurry outlet amount of a material opening and the position of an oil cylinder; the adjusting loop is connected to the opening and closing loop in parallel and suitable for controlling the oil cylinder to adjust the opening degree of the material opening according to the monitoring result of the detection module. The method is applied to the system. The device has the beneficial effects that the opening degree of the material opening can be accurately controlled through the adjusting loop, and manual adjustment is not needed; and closed-loop control is performed through the flow rate of slurry at the material port, the opening degree of the material port is adjusted in real time, and the stability of the discharging amount is ensured.

The invention discloses a folding arm frame control method and system, an aerial work platform and a storage medium, and relates to the technical field of engineering machinery. The control method comprises the steps that the absolute angle of a folding arm and the telescopic length of a main arm are obtained; the current value of an oil cylinder oil return proportional valve is determined according to the absolute angle of the folding arm and the telescopic length of the main arm; and the action of an oil cylinder oil return proportional valve is controlled according to the current value, and variable control over the oil return amount of the boom oil cylinder is achieved. On the basis of not changing the electric / hydraulic hardware configuration of the existing working platform, the current value of the oil return proportional valve of the oil cylinder is determined through the detected real-time boom posture, then the hydraulic oil return quantity of the boom action oil cylinder is dynamically adjusted according to the current value, the stability of the boom in the action process is ensured, and the working efficiency is improved. And the luffing operation of the boom is safer.

The utility model provides a hydraulic system of a sugarcane pile cutting machine. The hydraulic system comprises a sugarcane pile cutting machine body, a walking hydraulic system, a working device hydraulic system and an auxiliary device hydraulic system. The sugarcane pile cutting machine body comprises a front conveying part, a rear conveying part, a material box, a supporting and falling device, a header, a root cutting device, a supporting and falling device oil cylinder, a hopper lifting oil cylinder and a material door opening and closing oil cylinder. The hydraulic system of the sugarcane pile cutting machine can stably and efficiently complete the functions of walking, harvesting and the like of the sugarcane machine, is mature and stable, is sensitive in action response, can efficiently complete action control and sugarcane harvesting, adopts semi-rigid connection in front and back conveying, does not need to additionally add a synchronizing device, and is simple in structure and convenient to operate. The sugarcane pile cutting machine can slide relatively to prevent parts from being damaged during overload, one-key unloading of the material box can be achieved, operation steps are reduced, time is saved, and the sugarcane pile cutting machine is multiple in working parts, complex in structure and movement, stable, reliable, good in economical efficiency and high in efficiency.

An apparatus for operating a load-controlled hydraulic supply of an agricultural tractor includes a hydraulic pump which is adjustable with respect to the displacement volume for supplying pressurized hydraulic fluid, a proportional valve which is electrically actuatable, a primary hydraulic consumer to carry out a superordinate hydraulic function and to be directly connected to a conveying outlet of the hydraulic pump, a secondary hydraulic consumer to carry out a subordinate hydraulic function and to be connected to the conveying outlet of the hydraulic pump via the proportional valve, and a control unit configured to move the proportional valve into a closed valve position when the control unit recognizes that at least one of a required power of the primary and secondary hydraulic consumers exceeds the conveying capacity of the hydraulic pump and the subordinate hydraulic function of the secondary hydraulic consumer is inactive.

An example hydraulic system has: a hydraulic cylinder actuator having a cylinder and a piston axially movable in the cylinder, wherein the piston has a piston head that divides an internal space of the cylinder into a first chamber and a second chamber; a fluid reservoir; a pilot pressure source that generates a pilot fluid signal; and a valve assembly controlling fluid flow to and from the hydraulic cylinder actuator, wherein the valve assembly has a first workport fluidly coupled to the first chamber, a second workport fluidly coupled to the second chamber, a reservoir port fluidly coupled to the fluid reservoir, and a pilot port fluidly coupled to the pilot pressure source to receive the pilot fluid signal, wherein the pilot fluid signal actuates the valve assembly to fluidly couple the first workport and the second workport to the reservoir port, thereby operating the piston in a float mode.

A constant-flow control valve group, an auxiliary arm control module, a complete hydraulic system, and a crane. The constant-flow control valve group comprises: a cartridge valve; a cartridge reversing valve, comprising a working oil port on one side and a main oil return port and a reversing valve oil inlet selectively connected to the working oil port on the other side, the working oil port being connected to a control oil port of the cartridge valve, and the reversing valve oil inlet being connected to a main oil inlet of the cartridge valve; and a feedback on-off valve, disposed in a working feedback oil path connected between the main oil inlet of the cartridge valve and a main feedback oil port of the constant-flow control valve group. The auxiliary arm control module comprises the constant-flow control valve group and a main reversing valve. The complete hydraulic system comprises the auxiliary arm control module and an auxiliary arm luffing cylinder, and may further comprise a load-sensitive oil pump and a main valve. The present application can achieve the effect of directly connecting an auxiliary arm hydraulic system to an existing complete hydraulic system as a sub-module without altering the original system.

The utility model discloses a walking hydraulic system and a shear fork type lifting working platform. The system comprises a hydraulic oil tank, an oil pump, a first motor, a second motor, a first electromagnetic reversing valve, a second electromagnetic reversing valve, a third electromagnetic reversing valve, a fourth electromagnetic reversing valve, a first balance valve, a second balance valve and a flow distributing and collecting valve. An original two-position four-way electromagnetic directional valve is replaced by the third electromagnetic directional valve and the fourth electromagnetic directional valve, and the flow distributing and collecting valve is additionally arranged, so that the flow of the two motors is evenly distributed during low-speed walking, and the problems that long-distance linear walking cannot be achieved, and slipping and weakness are prone to occurring during low-speed walking are solved; the flow collecting opening of the flow distributing and collecting valve is connected with the second electromagnetic directional valve in parallel, oil ways are switched through the second electromagnetic directional valve without passing through the flow distributing and collecting valve, and the problems of high system pressure and high energy consumption caused by the fact that oil flows through the flow distributing and collecting valve during high-speed walking are solved.