410 results about "Critical speed" patented technology

A control method and apparatus for critical rotational speed avoidance in a compressor-expander set in a gas refrigeration system. By varying an opening of an antisurge or recycle valve, a shaft power used by the compressor in the compressor-expander set may be varied, thereby varying the rotational speed of the compressor-expander set to move it away from its critical speed zone. Additionally, a feedforward signal may be provided by a compressor-expander set control system to cause an antisurge valve for a recycle compressor to open upon a trip or shutdown of one compressor-expander set.

A circuit (10) for multiplying two floating point operands (A and C) while adding or subtracting a third floating point operand (B) removes latency associated with normalization and rounding from a critical speed path for dependent calculations. An intermediate representation of a product and a third operand are selectively shifted to facilitate use of prior unnormalized dependent resultants. Logic circuitry (24, 42) implements a truth table for determining when and how much shifting should be made to intermediate values based upon a resultant of a previous calculation, upon exponents of current operands and an exponent of a previous resultant operand. Normalization and rounding may be subsequently implemented, but at a time when a new cycle operation is not dependent on such operations even if data dependencies exist.

A transistor structure includes an insulated conductive gate spacer or a conductive layer under a nonconductive spacer, together forming a composite spacer, which is contacted and driven separately from the conventional gate of the transistor. The gate spacer, conductive layer of a composite spacer or a portion or portions thereof serve as a control or controls for the transistors taking the form of a second gate or second and third gates for the transistors. The transistors may be used throughout an integrated circuit or it may be preferred to use the improved transistor only in critical speed paths of an integrated circuit. Delays within circuits including the improved transistors are reduced since the drain voltage can be higher than VCC and the BVDSS and subthreshold voltage are substantially higher than standard LDD transistors. When the improved transistors are used selectively within an integrated circuit, the remaining devices can be structured as standard LDD transistors, using the gate spacers in a conventional manner, and/or as conventional transistors.

The invention discloses an aircraft flutter prediction system and method which are used for solving the technical problem that an existing flutter prediction system is poor in prediction accuracy. According to the technical scheme, the system comprises an excitation signal generator, an excitation executing mechanism, a signal acquiring module and a data processing and flutter prediction module, wherein excitation signals generated by the excitation signal generator are input into a steering engine, the steering engine drives a control plane to deflect through a power booster according to a predetermined instruction so that gas power can be generated and excitation can be formed, and the control plane deflects at different speeds according to different input signals so that different external excitation forces can be generated and a test part can be fully excited. The signal acquiring module is used for acquiring acceleration responses and external excitation force response signals. According to each mach number, the data processing and flutter prediction module can predict a flutter critical point of the test mach number just through a subcritical speed testing point, prediction accuracy can also meet the requirement when the speed testing point is far away from the flutter critical point, and the prediction accuracy of the flutter prediction system is improved.

The compressor-evaporator system for liquefied gas contained in a tank comprises, in addition to a deice for evaporation by heat exchange with a liquid and devices for conditioning and transferring gas to a pipeline, a motor-driven turbopump comprising a rotary assembly of high bending stiffness on a common shaft line, with at least one high pressure pump, a turbine, and a central electrical machine capable of being used in motor mode or in generator mode. The rotary assembly of the motor-driven turbopump is adapted to present a high speed of rotation, greater than 12,000 rpm, while remaining outside ranges for exciting critical speeds in rotation. All of the internal portions of the motor-driven turbopump are immersed in a cryogenic fluid that is the same as the liquefied gas contained in the tank. The internal cavities of the motor-driven turbopump that are under different thermodynamic conditions are separated by contactless dynamic seals. Electronic power circuits connected to an electricity network control the central electrical machine in motor mode or generator mode.

The invention relates to the cold gas dynamic spray technology and the laser technology, in particular to a cold gas dynamic spray method comprising laser irradiation, wherein, compressed gas which carries with metallic powder impacts against the surface of a plaque at supersonic speed to form a circular spray spot on the surface of the plaque; meanwhile, an elliptic irradiation laser speckle is formed directly ahead of the circular spray spot through laser beam irradiation; moreover, the elliptic irradiation laser speckle and the circular spray spot are partly overlapped. The invention can substantially reduce the particle critical speed during cold gas dynamic spray and increases splicing efficiency and strength to ensure structural stability of spray particles, thereby improving coating performance.

Several embodiments of a stiff, metallic hub for an energy storage devices are disclosed in the present invention. The stiff hub produces a critical velocity that is significantly greater than the design operating speed of the flywheel assembly so that resonant frequency is never reached during normal operation of the energy storage device's flywheel assembly. The stiff hub comprises a central core section that maintains a tight interference fit with the rotating shaft; an outer rim section that maintains a tight interference with the high-strength, low-density composite fiber rim, in which energy primarily is stored; and a web section that is situated therebetween, extending radially from the rotary shaft. At high operating speeds, the outer rim of the hub expands radially commensurate with expansion of the composite fiber rim so that enough of the outer rim remains in tight interference fit with the composite fiber rim to substantially minimize vibrations.

The invention discloses a flywheel energy storing device with a permanent magnet bearing and a thrust bearing which comprises an upper shaft, a lower shaft, a flywheel body, a permanent magnet bearing, a motor, a bearing seat, a damper and a container, wherein the bottom of the lower shaft is provided with a ball head; the ball head is positioned in a groove at the top of the bearing; a damper stator is embedded in a ring groove of an upper soft magnetic ring; a damper rotor is embedded in a ring groove at the upper part of the flywheel body, and the upper end surface of a rotor outer insulative magnetic ring is opposite to the lower end surface of a stator outer permanent magnetic ring; the upper end surface of a rotor outer permanent magnetic ring is opposite to the lower end surface of a stator middle insulative magnetic ring; the upper end surface of a rotor middle insulative magnetic ring is opposite to the lower end surface of a stator middle permanent magnetic ring; the upper end surface of the rotor inner permanent magnetic ring is opposite to the lower end surface of a stator inner permanent magnetic ring; and the upper end surface of the rotor inner permanent magnetic ring is opposite to the low end surface of the stator inner permanent magnetic ring. According to the flywheel energy storing device of the structure, the flywheel body can pass through the low order critical speed of rotation, and the whole flywheel energy storing device has favorable dynamic characteristics.

Magnet wires wound in slots in a lamination stack of a dynamoelectric machine are encapsulated, in whole or in part, with plastic. The plastic may be thermally conductive and have features molded therein that enhance heat transfer. The plastic may stiffen the armature and increase its critical speed. Characteristics of the plastic, its geometry and its distribution may be varied to adjust spinning inertia and resonant frequency of the armature. The magnet wires may be compressed into the slots, by application of iso-static pressure or by the pressure of the plastic being molded around them. Larger magnet wire can then be used which increases the power of the electric motor using the armature having the larger magnet wire. A two or three plate mold may be used to mold the plastic around the armature. Balancing features can be molded in place. The plastic can have a base polymer that is a blend of two or more polymers and various thermally conductive fillings.

The invention discloses a bend driving anti-turnover early warning control system and method for a liquid tank vehicle. The system comprises a GPS positioning module, a liquid level height acquisition module, a parameter storage module, an operation module, a decision-making module, an alarm module and a throttle control module. The method comprises the steps of collecting vehicle position and direction data through the GPS positioning module; acquiring the height of liquid in a liquid tank when the vehicle is still through the liquid level height acquisition module; calculating and obtaining a critical speed when the vehicle turns over through the operation module; through the decision-making module, comparing the critical speed and a driving speed, and determining the state of the vehicle; the alarm module and the throttle control module receive information of the decision-making module and conduct alarming and throttle control. By the adoption of the bend driving anti-turnover early warning control system and method for the liquid tank vehicle, when the bend driving speed of the liquid tank vehicle is relatively high, early warning can be provided for a driver, the vehicle speed can be controlled by controlling a throttle, and the purposes are achieved that the vehicle is prevented from turning over and the safety of personal and the vehicle is ensured.

The invention discloses a high frequency ultrasound elliptic vibration cutting device which comprises an ultrasound vibration unit and a casing unit. The ultrasound vibration unit is arranged in the casing unit. The casing unit comprises a base, A cover plate, B cover plate and an upper cover plate. The ultrasound vibration unit comprises an amplitude transformer, a vibrating body, A excitation source, B excitation source and C excitation source. The amplitude transformer is installed on the vibrating body. The end part of the amplitude transformer is provided with a cutting tool. The A excitation source and the B excitation source are arranged in parallel way and are adhered on the lateral side of the vibrating body. The C excitation source is installed on the lower part of the vibrating body. The A excitation source and the B excitation source form the driving power in horizontal direction. The C excitation source forms the driving power in vertical direction. The phase separation between two mutually vertical high frequency vibrations is applied for compounding an elliptic vibration at the point of the cutting tool. Thus, the processing surface roughness is lowered effectively. The cutting device works at the high vibration frequency of 100 kHz-200 kHz, so that the vibration chipping critical speed of the cutting tool is improved, and the processing efficiency is improved obviously. The amplitude transformer is adopted to be inserted in the vibration body, so that the installation is easy, and the practicality of the ultrasound elliptic vibration cutting can be promoted.

An inner tub of a washing machine is rapidly braked during a portion of a deceleration phase following an extraction phase of an overall spin cycle. A controller establishes the braking operation over a critical speed band or resonant frequency zone during which excessive vibrations would be developed. The critical speed band is preferably determined based on one or more signals received from speed, load, and/or out-of-balance sensors.

A natural gas production system prevents liquid accumulation in the wellbore and minimizes friction loading in the wellbore by maintaining production gas velocity above a critical minimum velocity. A pressurized gas is injected into the well to supplement the flow of production gas such that the velocity of the total gas flow up the well exceeds the critical velocity. A choke is fitted to the gas injection line, and total gas flows are measured by a flow meter. A flow controller compares the measured total gas flow rate against the critical flow rate, and determines a minimum gas injection rate required to maintain the total gas flow rate at or above the critical flow rate. The flow controller then adjusts the choke to achieve the desired gas injection rate. The injection gas may be recirculated production gas from the well, or a gas from a separate source.

The invention relates to a rail wagon bogie which is characterized by comprising a framework assembly, two sets of wheel set assemblies, four sets of single-stage suspension devices, a set of traction device, and two sets of dual-stage suspension devices; the framework assembly comprises two oppositely arranged side beams and two oppositely arranged cross beams; the side beam is in a U-shaped structure, one set of wheel set assembly is arranged on the outer side of each of the two cross beams, one set of rotation arm is arranged at each of two ends of each side beam to locate each single-stage suspension device, the traction device is arranged in the middle of the framework assembly, and each of the two side beams is provided with one set of full side bearing to bear the dual-stage suspension device. The rail wagon bogie is simple in structure and can achieve low power action, a vehicle has a higher critical speed and excellent curve negotiating performance by reasonably selecting the locating rigidity of a nodal point of the rotation arm and the longitudinal, transverse and vertical rigidities of the dual-stage suspension devices, the running safety of a rapid wagon at the speed of 160km per hour is guaranteed, and the rail wagon bogie can be widely applied to rail wagons.

A scanning electron beam computed tomographic system eliminates axial offset between target and detector by disposing the target, collimator, and detector such that active portions of the target and detector are always diametrically opposite each other. This result is achieved by providing a helical target, collimator, and detector, or by providing planar target, collimator, and detector components that are inclined relative to the vertical axis such that active portions of the target and detector are always diametrically opposite each other. Either configuration eliminates cone beam error and the necessity to correct for same. Further, the system can provide multi-slice scanning of an object that is in constant motion at a critical velocity, without having to interpolate data. Conventional helical scanning may still be undertaken. Detector elements can be disposed axially to improve signal/noise ratio and to produce a cone beam cancellation effect.

A method for producing gas from a well including a wellbore extending from a surface into a subterranean formation, wherein the well also produces liquid, the method including: (a) producing gas from a production zone in the subterranean formation through an annulus extending within the wellbore at a first velocity that is greater than a critical velocity, and (b) pumping liquid through a liquid tubing string after (a) to reduce a level of the liquid within the wellbore. The method also includes: (c) shutting in the annulus after (a) after the first velocity decreases below the critical velocity, wherein the annulus has a first cross-sectional area and the first production string has a second cross-sectional area that is less than the first cross-sectional area, and (d) producing gas from the production zone through the first production tubing string after (c) at a second velocity being greater than the critical velocity.

The invention relates to a low power consumption 5-DOF (Degree of Freedom) permanent magnet offset magnetic suspension bearing system belonging to a magnetic suspension bearing, which comprises a high-speed motor, a low power consumption permanent magnet offset axial and radial magnetic baring and a low power consumption permanent magnet offset radial magnetic bearing. 5-DOF (Degree of Freedom) suspension utilizes two radial magnetizing annular permanent magnetic bodies to establish a static offset magnetic field and runs through a 3-DOF (Degree of Freedom) magnetic bearing radial magnetic pole, a radial air gap, a rotor iron core, a rotor and a 2-DOF (Degree of Freedom) permanent magnet offset magnetic bearing radial stator to form a closed magnetic circuit; an axial winding generates control magnetic flux and offset magnetic flux superposition to control axial suspension; a radial control winding of three magnetic poles on the left end and the right end generates the control magnetic flux and the offset magnetic flux suspension; a triple/binary conversion principle of an alternating current motor is used to realize radial 4-DOF (Degree of Freedom) suspension; the system has a simple structure, high critical speed of rotation and low power consumption and has wide application prospect in the fields of aerospace, automobiles and motorcycles, mould machining, textile, chemical engineering machinery, etc.

Disclosed is a structural dynamic design method for a high-pressure rotor of an aircraft engine. The relationship between high-pressure rotor model design parameters and rotor vibration characteristics is determined, so that the design method and criterions are provided for dynamic design of the high-pressure rotor, and the method is of great guiding significance to the design of the high-pressure rotor of the aircraft engine. The method includes: establishing a dynamic model and a dynamic equation of the high-pressure rotor to obtain a nondimensionalization characteristic equation; introducing an equivalent critical speed, and determining a two-order critical speed range of a high-pressure rotor system according to the equivalent critical speed; changing a conventional equilibrium amount configuration method by configuring residual disequilibrium amount phases; configuring a ratio of rotor pole rotation inertia to mass center rotation inertia in design according to a specific design objective; establishing configuration criterions for a rotor bearing stiffness ratio. A conventional design process is changed, structural dynamic active design of the high-pressure rotor is realized, the design process is optimized beneficially, design cycle is shortened, and the method has important construction value.

The invention provides an axial split-phase internal stator permanent magnet biased magnetic suspension switched reluctance flywheel motor comprising an external rotor, a flywheel and an internal stator. The external rotor is packaged at the internal side of the flywheel in a laminating way. An internal stator iron core and an external rotor iron core are divided into m segments along the axis according to the phase number. The internal side of each segment of external rotor is equidistantly provided with 12 rotor poles along the circumference. The internal stator iron core is provided with 8 narrow tooth main magnetic poles and 4 wide tooth suspension poles. Main pole control coils and suspension control coils are respectively wound on the narrow tooth main magnetic poles and the wide tooth suspension poles. The coils on each narrow tooth main magnetic pole are interconnected in series to form a main pole winding. Every two of the control coils on each segment of wide tooth suspension pole are connected in series so as to form two sets of suspension windings in an orthogonal direction. The size of the system can be reduced and the critical speed of rotation can be enhanced; the suspension supporting loss can be reduced and the operation efficiency can be enhanced; and the stator poles are separately provided with the suspension poles, the main magnetic poles and magnetic isolating rings so that the control algorithm can be simplified and the suspension performance and the decoupling effect can be enhanced.

The invention belongs to the technical field of damping (vibration reduction), and particularly relates to a viscous damper. The viscous damper comprises a cylinder body, a cylinder cover, a piston rod, a piston head, a guide sleeve and sealing and viscous damping fluid. The cylinder body and the cylinder cover form a damping cavity, the damping cavity is divided into a first damping chamber and a second damping chamber through the piston head, a two-way holding valve is arranged on the piston head, and the two ends of the two-way holding valve are connected with the first damping chamber and the second damping chamber respectively. According to the viscous damper, the two-way holding valve is arranged on the piston head, when the speed of the viscous damper is larger than the critical speed, due to the fact that force exerted on a valve core of the holding valve is larger than preloaded pressure of a spring, the holding valve is closed, and consequently the output damping force of the viscous damper can reach a rated value. In addition, the viscous damper is compact in structure and convenient to install, and a two-way locking function can be achieved.