Showing papers on "Rotational speed published in 2000"

Control apparatus for hybrid vehicle

Abstract: By preventing engagement of an engaging part (clutch) under appropriate conditions, it is possible to effectively avoid the so-called surging phenomenon. When there is an engaging directive for the clutch, the rotational speed of the engaging element positioned at the output shaft side of the drive/regeneration motor (the clutch output rotational speed) is detected, and the gear ratio of the CVT is detected, and when the product of the rotational speed of the engaging element and the gear ratio of the CVT is equal to or below a predetermined value, complete engagement between the engaging elements is prevented, and control is conducted which makes the gear ratio large.

Spin valve sensors

Abstract: This paper demonstrates spin valve sensor applications as read elements in storage systems, or, when in a Wheatstone bridge configuration, as rotational speed control devices (for ABS systems), high current monitoring devices for power lines, and positioning control devices in robotic systems. For recording heads, shielded spin valve sensors are adequate for high linear density recording. A tape head was fabricated with output 400 μV per micron of trackwidth, with a D50 value of 100 kfci, and signal loss of −0.34 dB/kfci. For rotational speed measurement, spin valve bridge sensors with flux guides were used, yielding a 400-mVpp amplitude, and square wave output with rise/fall times below 70 μs, when excited by a magnetized wheel. Amplitude is independent of speed (0–3000 rpm), and of sensor to wheel separation (0.5–2.0 mm). For power line applications, currents up to 2100 A (at 50 Hz) could be measured with a sensitivity of 35 μVrms/A and deviations from linearity of ±1.5%. In robot position control, a maximum error of ±9 μm over a ±0.5-mm span was obtained. In the two last cases, bridges without flux guides are used to maximize linear response.

3‐D numerical simulations of nonisothermal flow in co‐rotating twin screw extruders

Abstract: Three-dimensional nonisothermal flow simulations in the kneading disc regions of co-rotating twin screw extruders were performed using a finite element method. The standard Galerkin method and penalty function scheme were applied to the flow field. The streamline-upwind/Petrov-Galerkin scheme was used in the temperature field to reduce numerical oscillation. The simulations were carried out under the operational conditions of The Japan Steel Works TEX30 machine for various rotational speeds. The configuration was ten 2-lobe kneading discs with a 90° stagger angle. Experimental observations were also performed to validate the numerical simulations under the same operational conditions. The pressure in front of the tip in the rotation direction was higher than behind the tip, and the region behind the tip sometimes had a negative value. Since variation of the pressure gradient in the axial direction causes forward and backward flows in the disc gap regions, the disc gap regions play an important role for mixing. The temperature becomes higher with increasing rotation speed due to high viscous dissipation. A high temperature was observed on the disc surface, in the disc gap, and in the intermeshing regions. The numerical results of pressure profiles with the rotation and the temperature in the axial direction were in good agreement with the experimental observations.

Driving control apparatus for industrial vehicle

Abstract: An industrial vehicle includes a transmission, which is coupled to an engine by a torque converter. When the vehicle is accelerating, the rotational acceleration of driving wheels is computed based on the rotational speed of the driving wheels. A traction control procedure is executed based on the rotational acceleration for eliminating spinning of the driving wheels. When the vehicle is decelerating, the rotational deceleration of the driving wheels is computed based on the rotational speed of the driving wheels. An anti-lock brake control procedure is executed based on the rotational deceleration for preventing the driving wheels from locking. As a result, skidding of the driving wheels is reliably prevented by a simple structure.

Motor control device capable of driving a synchronous motor with high efficiency and high reliability

Abstract: A control unit is arranged for a synchronous motor formed of a rotor provided with a magnet. The control unit includes a 180°-conduction drive unit for performing 180°-conduction drive of the synchronous motor, a 120°-conduction drive unit for performing 120°-conduction drive of the synchronous motor, a rotation speed calculating unit for calculating the motor rotation speed, a rotation-speed-vs.-efficiency table unit storing an efficiency relative to a rotation speed of the motor, and a drive method selecting unit for selecting an optimum drive method for the current rotation speed based on the current rotation speed and information stored in the rotation-speed-vs.-efficiency table unit. Thereby, the synchronous motor performs 120°- or 180°-conduction drive in accordance with the current rotation speed to achieve the drive with an optimum efficiency.

System with fan speed synchronization control

Abstract: A system, such as a computer system, has cooling fans (30), each having a fan motor (36) and fan blades (38). The fan motor (36) operates to rotate the fan blades (38) at a variable rotational speed. A frequency generator (46) generates a reference speed signal having a reference frequency and a reference phase. Tachometers (50) measure the variable rotational speeds of the fan blades (38) of corresponding fans (30) and provide corresponding fan speed signals representative of the variable rotational speeds of the corresponding fans (30). Each fan speed signal has a fan frequency and a fan phase. Motor controllers (40) control the variable rotational speed of corresponding fan blades (38) of corresponding fans based (30) based on the reference speed signal and the corresponding fan speed signals.

Peak power energy storage device and gravitational wave generator

Abstract: An energy storage device (10) comprising a large scale flywheel supported by a fluid bearing (44, 45). The flywheel has a diameter greater than 100 feet and a concrete, steel-reinforced rim (11) weighing in excess of 1000 metric tons. In off peak periods the apparatus is operated as a motor with energy input causing the rim (11) to rotate up to a predetermined speed and to maintain rotation at that speed in the power take off mode. During peak power time periods, the operation of the electrical circuitry is reversed and the flywheel generates electrical energy which is delivered by the storage device to the power grid. As energy is delivered, the rotational speed of the flywheel diminishes and gravitational waves capable of being shaped and modulated are generated. The unique electrical circuit utilizing coils (26) and power transistors (30, 32) under computer software control facilitates operation as a peak power energy storage device or as a gravitational wave generator.

Detected signal processing device for rotating sensor and detected signal outputting method therefor

Abstract: The rotation of a rotating magnet is detected by magnetic sensors. The rotational speed is detected from pulse signals detected by magnetic sensors, and the rotational direction thereof is detected from the difference in the way of making a shift in phase. Signals different in pulse width are generated according to the rotational direction. A signal selection circuit outputs a corresponding pulse signal with timing for the rotational speed. A rotational speed determining circuit outputs a decision signal Sf of a high level when the rotational speed reaches a predetermined speed. When a self-diagnostic circuit determines that the magnetic sensors have malfunctioned, a binary error code generating circuit generates an error signal Sg and a 4-bit error code signal Sh. When the signal Sf of the rotating magnet is brought to a high level, the signal selection circuit associates a signal corresponding to the rotational direction with data of “1” or “0” to output an error code signal and allows a current output circuit to output an output current Is.

Diagnostic system for electric motor

Abstract: A diagnostic system for electric motors, such as those used in automotive applications. The system comprises a controller for supplying a desired command current to said electric motor, a sensor for measuring the rotational speed of the motor, a sensor for measuring the actual current supplied to the motor by the controller, a diagnostic control unit adapted to receive the measured rotational speed, measured supplied voltage, and a command current level value as inputs. The diagnostic control unit further comprises circuitry to calculate an estimated actual current drawn by the motor and to signal an error condition if the estimated actual current is not within a calculated valid range.

Experimental and Numerical Investigation of the Influence of Rotor Blades on Hot Gas Ingestion Into the Upstream Cavity of an Axial Turbine Stage

Abstract: The phenomenon of hot gas ingestion through turbine rim seals is experimentally and numerically investigated for a complete stage with nozzle guide vanes and uncooled helicopter turbine rotor blades.In the experimental part, two different geometrical rim seal configurations are examined: 1. a simple axial gap between rotor and stator disk and 2. an axial gap between the rotor disk and a rim seal lip at the periphery of the stator disk. The results obtained are compared to experiments carried out for the same geometry but without rotor blades.The influence of the presence of rotor blades on hot gas ingestion is examined for different parameters such as nondimensional seal flow rate, Reynolds number in the turbine annulus and rotational speed. For the determination of the sealing efficiency measurements of carbon dioxide gas concentration are carried out in the wheelspace. The static pressure distribution in the cavity is measured by means of pressure taps at the stator disk.It is shown that for configuration 1 the presence of rotor blades causes a considerable drop in sealing efficiency whereas for configuration 2 the sealing efficiency increases significantly.In the numerical part results of three-dimensional unsteady CFD calculations for configuration 2 are compared to steady calculations for the same configuration without blades. Predictions of hot gas ingestion and carbon dioxide gas concentration in the hub region and inside the cavity are presented. Special emphasis is put on unsteady effects arising from rotor movement.A local ingestion zone rotating at approximately half rotor speed is numerically predicted. As indicated by the experimental results the rotor blades have a positive influence on the predicted sealing efficiency.Copyright © 2000 by ASME

Dynamic stability of a rotating shaft driven through a universal joint

Abstract: The dynamic stability of a system composed of driving and driven shafts connected by a universal joint is investigated. Due to the characteristics of the joint, even if the driving shaft experiences constant torque and rotational speed, the driven shaft experiences fluctuating rotational speed, bending moments and torque. These are sources of potential parametric, forced and flutter type instabilities. The focus of this work is on the lateral instabilities of the driven shaft. Two distinct models are developed, namely, a rigid body model (linear and non-linear) and a flexible model (linear). The driven shaft is taken to be pinned at the joint end and to be resting on a compliant damped bearing at the other end. Both models lead to sets of differential equations with time dependent coefficients. For both rigid (linear and non-linear) and flexible models, flutter instabilities were found but occurred outside the practical range of operation (rotational speed and torque) for lightly damped systems. Parametric instability charts were obtained by using the monodromy matrix technique for both rigid and flexible linear models. The transmitted bending moments were found to cause strong parametric instabilities in the system. By comparing the results from the two linear models, it is shown that the inclusion of flexibility leads to new zones of instability, not predicted by previous models. These zones, depending on the physical parameters of the system, can occur for practical conditions of operation. Using direct numerical integration for a few sets of specific parameter values, forced resonances were found when the rotational speed reached a value equal to a natural frequency of the system divided by two.

A conservative control strategy for variable-speed stall-regulated wind turbines

Abstract: Simulation models of a variable-speed, fixed-pitch wind turbine were investigated to evaluate the feasibility of constraining rotor speed and power output without the benefit of active aerodynamic control devices. A strategy was postulated to control rotational speed by specifying the demanded generator torque. By controlling rotor speed in relation to wind speed, the aerodynamic power extracted by the blades from the wind was manipulated. Specifically, the blades were caused to stall in high winds. In low and moderate winds, the demanded generator torque and the resulting rotor speed were controlled to cause the wind turbine to operate near maximum efficiency. Using the developed models, simulations were conducted of operation in turbulent winds. Results indicated that rotor speed and power output were well regulated. Preliminary investigations of system dynamics showed that, compared to fixed-speed operation, variable-speed operation caused cyclic loading amplitude to be reduced for the turbine blades and low-speed shaft and slightly increased for the tower loads. This result suggests a favorable impact on fatigue life from implementation of the proposed control strategy.

Overspeed detection techniques for gas turbine engine

Abstract: Unique systems and methods are disclosed to detect and remediate an overspeed condition of a gas turbine engine. Such techniques include sensing rotational speed of a rotating member of a gas turbine engine and providing a first speed threshold that varies with rotational acceleration of this member over a predefined range. An overspeed condition of the gas turbine engine is detected if the rotational speed exceeds this first speed threshold and a second speed threshold. This second speed threshold is greater than or equal to the first speed threshold when the overspeed condition is detected. In response to the overspeed detection, a fuel valve may be actuated to adjust fuel flow to the engine. In one embodiment, an analog circuit compares the first and second speed thresholds to the rotational speed and controls current flow through an actuator for an overspeed fuel valve associated with the engine.

Continuously variable transmission

Abstract: PROBLEM TO BE SOLVED: To provide a continuously variable transmission incorporating a belt type continuously variable speed change mechanism, which can carry out continuously variable speed change in a wide speed changing range from a neutral position to a maximum forward or backward speed with no shocks caused by speed change. SOLUTION: A continuously variable transmission comprises first and second belt type continuously variable speed change mechanisms 21, 22 and a differential gear mechanism 10. In the respective belt type continuously variable speed change mechanisms 21, 22, the drive side pulleys 24, 31 are directly or indirectly coupled to an input shaft 1, and a driven side pulley 25 in the first belt type continuously variable speed change mechanism 21 is coupled to a sun gear 12 in the differential gear mechanism 1 while a driven side pulley 32 in the second belt type continuously variable speed change mechanism 22 is coupled to a carrier 15 in the differential gear mechanism 10. An internal gear 16 is coupled to the output shaft 2. Through speed change by the belt type continuously variable speed change mechanisms 12, 22, change-over among the normal rotation, the reverse rotation and the neutral position can be made while continuously variable speed change can be made from the neutral position to the maximum rotational speed, and during operation on normal or reverse rotation, the continuously variable speed change can be made from the neutral position to the maximum rotational speed.

Frequency behaviour and speed control of piezomotors

Abstract: The rotational speed of a piezomotor is directly linked to the vibration velocity of its stator. Because some drifts of the stator characteristics lead to an unwanted variation of the motor speed, a control is necessary. This paper discusses the origins of drifts in travelling wave ultrasonic motors (TWUM). The typical behaviour of this kind of motor and its consequences on speed control are presented. While control is easily achieved when the applied torque is constant, variations of this quantity make more difficult to obtain an efficient method. Finally, the basic idea of this paper is to derive a general control method by using the absorbed current, which is the only always detectable quantity.

Motor torque controller

Abstract: PROBLEM TO BE SOLVED: To reduce oscillation and a noise level by providing an inverter for supplying energization so that an electrical angle may be higher than 120 degrees and equal to 180 degrees or lower, and a torque control means for controlling the generated torque of a motor so as to meet torque generated by the motor and load torque generating a load factor SOLUTION: A torque control means 11 controls energization to a motor 4 so as to meet the rotational acceleration or the rotational speed of the rotor of a motor 4, and reduces a rotational pulse The torque control means 11 controls the rotational acceleration of the rotor so as to become zero in order to control the pulse The torque control means 11 difference the rotational speed using the rotor acceleration detecting means 12, and detects the rotational acceleration An acceleration control means 13 outputs a torque command correction amount which bring the acceleration to zero, to an inverter 3

Generator and generator apparatus

Abstract: Two generation systems 3, 8 each including inverter 8 are switched over between series connection and parallel connection by switching section 5 . Reference waveform signals are mutually communicated between the two generation systems through communication lines 6 . When a phase difference between these two reference waveform signals is within a predetermined range, the inverters are driven to generate an output alternating current. One of the conduction angles of thyristors 3 a, 3 a in two converters 3, 3 which is larger than the other is inputted to a deviation detector 42 . Based on a deviation of the conduction angle inputted from a target conduction angle, an updated target rotational speed is set in a calculator 44 . A throttle controller 48 controls a throttle opening angle so that an actual rotational speed converges into the target rotational speed. A ground fault is judged based on a potential difference across one node point in a first arm, connected to the earth and the other node point in a second arm of a resistance bridge provided across a pair of output terminals of either one of the inverters.

Controller for vehicle with continuously variable transmission

Abstract: PROBLEM TO BE SOLVED: To provide a controller for a vehicle with a continuously variable transmission, allowing acquisition of a sufficient acceleration feeling to acceleration operation of a driver. SOLUTION: When acceleration requirement is decided by an accelerator operation decision means 86, a control means 90 sets a target drive force POWER higher than a normal target drive force calculated in normal operation of an accelerator pedal 71, sets an accelerating target rotational speed NINLINE higher than a normal rotational speed calculated in the normal operation, increasing at a prescribed gradient β to increase of a vehicle speed, and controls output torque of an engine 12 and a change gear ratio γ of the continuously variable transmission 18 such that the set target drive force POWER is accomplished and that an input shaft rotational speed N IN of the continuously variable transmission 18 becomes the set accelerating target rotational speed NINLINE. Accordingly, when the acceleration requirement is performed by the driver, the target drive force can be increased, and the output rotational speed of a power source can be increased, so that the sufficiently high acceleration feeling can be obtained from the vehicle to a requirement output amount. COPYRIGHT: (C)2006,JPO&NCIPI

Highly turbulent Couette Taylor bubbly flow patterns

Abstract: We present the results of experimental study of a Couette–Taylor system with superimposed axial flow and an upper free surface, in the high Taylor number regime. At large Taylor numbers, when the rotational speed of the inner cylinder increases, bubbles created near the free surface are distributed throughout the test section and permit the study of the spatial and temporal properties of turbulent flows using visualization techniques. In addition to classic travelling Taylor vortices, intermittent pulses of vortices with higher phase velocities are also observed. These patterns are described in terms of the rotational speed and the intensity of the throughflow.

Reduced weight design of a flexible rotor with ball bearing stiffness characteristics varying with rotational speed and load

Abstract: This paper presents an effective design approach for reducing the weight of a flexible rotor in ball bearings with rotational speed and load dependent stiffness characteristics under constraints on the system eigenvalues and bearing fatigue life. Design variables are chosen to be the inner radii of shaft elements, the positions of ball bearings, and the preloads on the bearings. The stiffness characteristics of high speed ball bearings are completely described as functions of applied loads and spin speed, and applied to the dynamic behavior analysis of a rotor-bearing system. A transfer matrix method is used to obtain eigenvalues of the system and an augmented Lagrange multiplier (ALM) method is employed as an optimization technique. A multi-stepped rotor supported by two angular contact ball bearings is analyzed and designed to show the speed and load dependent stiffness effect on the system dynamic behavior and to demonstrate the effectiveness of the proposed optimum design approach. The results show that the effect of the stiffness on the system dynamic behavior is noticeable and that the suggested design approach is effective.

Vehicular transmission control system

Abstract: After the engine rotational speed Ne has become below a reference rotational speed Neo, which is lower than an idling rotational speed of the engine, and after the pressure PL of oil passages 103a and 103b has begun to decrease, for a predetermined time, the currents supplied to electromagnetic valves 45 and 46 are adjusted to generate, in each electromagnetic valve, a second biasing force electromagnetically in a magnitude that can supplement a decrease in a third biasing force which is generated by the back pressure led through an oil passage 107 or 108, respectively, and which decreases as the pressure of the oil passages 103a and 103b decreases. After the above mentioned predetermined time has elapsed, the currents supplied to the electromagnetic valves 45 and 46 are set almost to zero.

Rotator driving device, image forming apparatus using the rotator driving device, and method of driving rotator

Abstract: Rotational force of a driving motor is transferred to a photosensitive drum via a planetary-roller reduction device, so that the photosensitive drum is rotated. A speed detector set on the shaft of the photosensitive drum detects the rotational speed of the photosensitive drum. In accordance with the detected rotational speed of the photosensitive drum, the rotational speed of the driving motor is adjusted so that the photosensitive drum is rotated at a constant speed.

Control device for a hybrid vehicle

Abstract: A control device for a hybrid vehicle that can avoid component damage due to such operation, and can continue driving smoothly even in the case that operation that does not occur during normal driving occurs. In the case that the main contactor 11, which has been turned ON, is turned OFF due to the ignition being turned OFF while the motor 2 has a high rotation speed, and then the ignition is turned ON again, the engine control device 4 controls engine 1 so that the rotation speed of the engine 1 becomes the rotation speed at which the voltage generated by regeneration of motor 2 is equal to or below the withstanding voltage of the power drive unit 7. Subsequently, when the main contactor 11 is turned ON by the engine speed falling, the engine control device 4 controls the engine so that the engine speed becomes equal to or less than 7000 rpm.

Characteristics of an ultrasonic motor capable of generating a multi-degrees of freedom motion

Abstract: The authors developed a bar-shaped ultrasonic motor capable of generating a multi-DOF motion. The multi-DOF ultrasonic motor consists of a bar-shaped stator and a spherical rotor. The spherical rotor is rotated around three perpendicular axes by the three natural vibrations excited on the stator. In the present study, the driving and control characteristics around one driving axis, which is perpendicular to the stator's geometric axis, are measured in detail, namely the relationship between the frequency of the input signal and the rotational speed, the relationship between the torque and the rotational speed and the step response of the ultrasonic motor, are measured. The maximum rotational speed and the maximum torque are 183 rpm and 5 mNm, respectively. The rotational speed was controlled successfully.

Fan with preset characteristic curve

Abstract: A tan having a fan wheel and an electric motor driving it, and a control unit for controlling the motor output as a function of fan-specific parameters. An actual-value signal corresponding to an actual rotational speed of the fan is measured and compared with a control signal corresponding to a required speed, and the actual speed is adjusted to the required speed by means of the control unit, wherefore the actual speed and the actual motor current or supply current are measured and conducted to a microcontroller as input signal variables, whereby the fan-specific data such as wheel diameter, density of the conveying medium, fan coefficients, motor coefficients, and a preset artificial characteristic curve ps=ƒ({dot over (V)}s ) are stored in the microcontroller as default values. The microcontroller generates the required-speed signal, which is a function of the electrical current variables and the actual speed, based on the preset artificial characteristic curve ps=ƒ({dot over (V)}s) where ps=required operating pressure and Vs=required volume flow.

Numerical modeling of helical flow of viscoplastic fluids in eccentric annuli

Abstract: Helical flow of viscoplastic Herschel-Bulkley fluids in concentric and eccentric annuli with rotating inner cylinder was investigated numerically. Similar flows occur in drilling operations of oil and gas wells. A finite volume algorithm with a nonstaggered grid system and a nonorthogonal curvilinear coordinate system to handle irregular geometry of an eccentric annulus was used to analyze the problem. Papanastasiou's modification of the Herschel-Bulkley (Yield-Power-Law) constitutive equation was used to model the shear rate-dependent viscosity of a viscoplastic fluid. For a fixed axial pressure gradient, the axial flow rate increased with increasing rotational speed of the inner cylinder. The discharge, as well as torque required to rotate the inner pipe, increased with increasing eccentricity for a fixed axial pressure gradient and inner cylinder rotational speed. Discharge also increased with increasing axial pressure gradient at a fixed eccentricity and rotational speed of the inner pipe. The flow field in an eccentric annulus is complex because vigorous secondary flow is produced in addition to the primary axial helical flow. Blockage at the narrow part of the eccentric annulus, when present, intensifies this secondary flow, with the discharge decreasing initially, then increasing, and decreasing again with increasing height of the blockage.

DC motor rotation detecting apparatus and DC motor rotation control apparatus

Abstract: A rotation detector apparatus and a rotation control apparatus for the DC motor is disclosed wherein rotational operations of a rotor of the DC motor are controlled by detecting at least one of the rotational direction, the rotational speed, the cumulative rotation number, and the rotational position of the rotor The pulsed output signal from at least one motor rotor rotation detector brush is processed by signal processing circuitry to regulate the at least one of the rotational direction, the rotational speed, the cumulative rotation number, and the rotational position of the rotor