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5277 results about "Electro hydraulic" patented technology

Tractor automatic navigation control system and method thereof

The invention provides a tractor automatic navigation control system. The system comprises a navigation control device, a steering control unit and an electro-hydraulic proportion steering executing device, wherein the navigation control device receives GPS positioning data in real time, calculates a lateral deviation between a current tractor position and an operation navigation target, calculates a target steering angle of a steering wheel in a current control period according to the lateral deviation and a tractor running speed value measured in real time, converts the target steering angle into a steering control command and then sends the steering control command to the steering control unit; the steering control unit judges whether a steering angle measured value of the steering wheel of the tractor is less than a preset limit value; if the steering angle measured value is less than the preset limit value, the steering control unit compares the target steering angle with the measured value, calculates a PWM duty cycle according to a steering angle difference value and outputs a control signal for driving the electro-hydraulic proportion steering executing device; and the electro-hydraulic proportion steering executing device responds to the PWM control signal and controls the flowing direction and the flowing speed of oil of a tractor steering system by the opening of a valve core of an electro-hydraulic proportion direction valve to make a piston of a steering hydraulic cylinder extend out or retract to deflect the steering wheel to the target steering angle.
Owner:BEIJING RES CENT FOR INFORMATION TECH & AGRI

2D hydraulic-power-assisted electro-hydraulic proportional reversing valve

The invention provides a 2D (2-dimensional) hydraulic-power-assisted electro-hydraulic proportional reversing valve, which comprises a valve body, a valve core, a valve sleeve, a linear electro-mechanical converter and a compressive-torsional coupling, wherein the valve core, the compressive-torsional coupling and the linear electro-mechanical converter are coaxially connected; an output shaft of the linear electro-mechanical converter is fixedly connected with an input end of the compressive-torsional coupling; an output end of the compressive-torsional coupling is fixedly connected with the right end of the valve core; a sensitive cavity is formed by the left end of the valve core, the valve sleeve and a left cover plate; a pair of axisymmetric high pressure holes and a pair of axisymmetric low pressure holes are respectively formed on the surfaces of shoulders of the valve core in the sensitive cavity; a pair of axisymmetric sensing channels are arranged on the inner surface of the valve sleeve outside the sensitive cavity; and one end of each receptive channel is communicated with the sensitive cavity, and the other ends of the receptive channels cover areas between adjacent high pressure holes and low pressure holes. The 2D hydraulic-power-assisted electro-hydraulic proportional reversing valve not only has the characteristics of high flow rate, high working pressure, and the like of an ordinary pilot-control type electro-hydraulic proportional valve, but also fulfils a proportional control function like a direct-actuated proportional valve under the circumstance of zero pressure (pressure loss).
Owner:ZHEJIANG UNIV OF TECH

Microcomputer-controlled electro-hydraulic servo rock tri-axial dynamic shear-seepage coupling multifunctional test method

A microcomputer-controlled electro-hydraulic servo rock tri-axial dynamic shear-seepage coupling multifunctional test method belongs to the technical fields of rock mechanics and engineering technology and is characterized in that a test apparatus is composed of a loading system, a sealing system, a multiphase fluid injection system, an acoustic emission monitoring system, a deformation monitoringsystem and a data collection system. The test method not only solves technical problems that a tri-axial pressure chamber cannot be used for performing large displacement shear-seepage coupling of rocks under high confining pressure and high seepage pressure, and also can achieve various extended functions on the basis of the technology. The apparatus can achieve servo control loading of force, displacement and strain rate in shear direction and injection seepage of a multiphase fluid during dynamic shear. In addition, the apparatus is equipped with a temperature control system for performingconstant temperature control to the tri-axial pressure chamber at 0-200 DEG C; therefore, a series of extended experiments of dynamic shear-seepage coupling features of rocks under effect of temperature can be carried out.
Owner:TAIYUAN UNIV OF TECH

Automatic leveling system and method for six-point support bridging platform

InactiveCN102174794AGuaranteed self-levelingHigh speedBridge erection/assemblyElectro hydraulicEngineering
The invention discloses an automatic leveling system and method for a six-point support bridging platform; six supporting legs are respectively provided with a pressure sensor and respectively connected with a hydraulic device; each hydraulic device is connected with the pressure sensor and an electro-hydraulic servo valve; and a controller is respectively connected with an alarm, a double-shaft tilt sensor, each pressure sensor and each electro-hydraulic servo valve. Coarse adjustment is performed firstly, and then fine adjustment is performed; the coarse adjustment comprises the steps of: inputting a sensed pressure signal of each supporting leg to the controller by the corresponding pressure sensor on the supporting leg, if the pressure value of the supporting leg is less than a preset value in the controller, controlling the alarm to emit an alarm by the controller, or else, performing the fine adjustment; and the fine adjustment comprises the steps of: keeping two middle auxiliary supporting legs still, adjusting two forward supporting legs and two backward supporting legs, keeping the highest supporting leg still, firstly leveling an X direction, and then leveling a Y direction. The automatic leveling system and method for the six-point support bridging platform can ensure that the platform can be automatically leveled in an outdoor severe environment, the good leveling precision and speed can be obtained, and strong environmental applicability and safety are provided.
Owner:JIANGSU UNIV OF SCI & TECH
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