Showing papers on "Damping torque published in 1987"

Instantaneous Torque Control of Electric Motor Drives

Abstract: In the control of adjustable speed drives, the performance of inexpensive digital integrated circuits is approaching the stage where traditional control algorithms may be displaced by new algorithms that better exploit their speed and the functional capabilities of their software. The concept of ``instantaneous torque control'' is introduced as an objective worth pursuing in the application of such digital IC's to drive systems. Instantaneous torque control would in principle permit the fastest possible response and the elimination of torque ripple, along with many other advantages not possible with conventional control algorithms, most of which are set up to control a time-averaged torque. Some of the fundamental principles of instantaneous torque control are developed for the switched reluctance motor, which is used as an example because, like the brushless dc permanent-magnet motor with concentrated windings, it has the potential for rapid response, but it can have appreciable torque ripple with unfavorable firing angles. A reference frame transformation that would eliminate the rotor position from the voltage and torque equations is not known for either of these machines. This opens up a number of interesting questions as to the generality of instantaneous torque control algorithms, and whether they can be incorporated into the general or unified theory of electrical machines.

Motor-driven power steering system for vehicles

Abstract: A motor-driven power steering system for an automotive vehicle has a drive control device for applying a driving signal to an electric motor for generating assistive torque to be applied to an output shaft, based on output signals from a torque detecting mechanism which detects a steering torque acting on an input shaft. The system detects a freely returning state of a steering wheel to dampen the electric motor when prescribed conditions are met. The range of the prescribed conditions is widened as the speed of travel of the automotive vehicle is increased.

Method of controlling damping force of damper

Abstract: The damping force of a damper on a motor vehicle is automatically controlled dependent on the running condition of the motor vehicle and the road condition in which the motor vehicle travels. An acceleration of vertical vibration of the motor vehicle body is detected by a sensor, and a binary pulse signal indicative of a variation in the acceleration is produced. Then, a first signal is generated on the basis of whether the pulse duration of the binary pulse signal is at least a prescribed value or smaller than the prescribed value. Thereafter, a second signal is produced indicating the magnitude of the absolute value of the acceleration. Finally, the damping force of the damper is selectively adjusted to hard, normal, and soft settings based on a combination of the first and second signals.

Method and apparatus for investigating drag and torque loss in the drilling process

Abstract: Drilling conditions are analyzed by, for example, measuring the torque applied at the surface to the drill string and the effective torque acting on the drill bit. The applied torque and effective torque are compared to determine torque loss. Likewise, applied weight on the drill string and effective weight acting on the drill bit may be measured and compared to determine drag losses. These measurements and comparisons may be done in real-time to diagnose unfavorable drilling conditions. The torque or weight measurements may be used to calculate a variable coefficient of friction acting on the drilling string. Trends in the torque or weight losses, or in the value of the coefficient of friction, may be observed on a plot of these quantities as a function of depth.

Hydraulic vibration damper having adjustable damping valve

Abstract: An adjustable damping valve for use on a hydraulic vibration damper, gas pressure damper or hydropneumatic suspension, which regulates the damping force, regardless of the orientation, and is variable in the regulation of the throughput, thereby providing a rapid switching frequency response. The damping valve has at least one electromagnet. In the preferred embodiment, each electromagnet can be controlled individually. Further, each electromagnet has a coil body with a winding and an armature. The armature is immersed in a fluid in the flow connection during operation. The armatures of the electromagnets interrupt and open directly the flow connection variably and quickly between an upper damping chamber of the vibration damper and a pressure equalization chamber. In one embodiment, there are a number of individual flow connections with corresponding electromagnets distributed over the circumference for fast action.

Analysis of Continuum and Reduced Shaft Models in Evaluating Turbine-Generator Shaft Torsional Response following Severe Disturbances on the System Supply

Abstract: The paper examines use of continuum and reduced models of turbine-generator shafts in evaluating torque response following incidence and clearance of severe disturbances on the system supply. Using airgap torque which results from incidence and clearance of system disturbances at fault current zeros, torque excitation which acts along the active length of the generator rotor for each torsional vibration is determined by Fourier analysis. Amplitude of torsional vibration at each shaft cell for each modal vibration is determined from the torque prime mover and generator shaft sections of interest for each modal vibration is then calculated. These components, together with the steady-state component (and that due to rotor swing), are summed as absolute values to give approximate peak torque at critical shaft sections. Presented results illustrate torque excitation and shaft torque estimated from continuum, simple and stiffness-adjusted shaft models as a function of fault clearing time following L-L-...

Wideband electromagnetic damping of vibrating structures

Abstract: The damping of vibrations in a mechanical structure is accomplished while minimizing the impact on the design and operation of the structure through the use of a plurality of attachable vibration damping elements. Each vibration damping element contains: an accelerometer, an integrator, mixer, power amplifier, and a force actuator. The accelerometer measures the motion of the vibration in the structure at its attachment point and produces an acceleration measurement signal. The integrator integrates the acceleration measurement signal to produce a velocity measurement signal. The mixer produces a composite motion signal by mixing the acceleration measurement signal with the velocity measurement signal. The power amplifier adjusts the phase and amplitude of the composite motion signal to drive the force actuator to damp the sensed vibration along one dimension at the attachment point of the force actuator. By placing three vibration damping element at right angles to each other at a location on the structure, three dimensional vibration damping is obtained at that point.

Device for damping the self-movements of the masses of a linear two-mass oscillator

Abstract: A description is given of a device for damping the self-movements of the masses of a linear two-mass oscillator such as that which is present, for example, in a wheel-suspension system of a motor vehicle with two spring-damper systems connected in series. The spring-damper system arranged between the two masses is assigned a controller, the actuating signal of which influences the transmission behaviour of a controlled damping member in such a way that the damping force is proportional to the sum of the separately weighted absolute velocities of the two masses. In this way, it is possible to raise the oscillation screening of the two spring-damper systems in the frequency range between the natural frequencies of the two systems and to reduce the thermal loading of the damping member.

Shock absorber control device

Abstract: PURPOSE:To easily further accurately control damping power by estimating the relative displacement between a car body and a wheel being based on the damping power of a shock absorber further deciding a road surface condition being based on a period of the relative displacement while switching the damping power in accordance with the road surface condition. CONSTITUTION:Each damping power of a number of shock absorbers 6 (6a-6d), provided in a vehicle, is detected by a number of load sensors 1a-1d respectively serving as a damping power detecting means 1. Each detected damping power is input respectively to a microcomputer 4 equipped with a CPU41 and other each equipment 42-46. Here being based on each damping power, the relative displacement between a car body and a wheel is estimated. While of the estimated relative displacements, in accordance with a period of the relative displacement larger than the predetermined displacement, a road surface conditioner for the vehicle running is decided. Thereafter, in accordance with the decided road surface condition, the damping power of each shock absorber 6a-6d is switched by a driving circuit 5.

Effect of Fault Clearing and Damper Modelling on Excitation and Decay of Vibrations in Generator Shafts Following Severe Disturbances on the System Supply

Abstract: The paper examines the effect damper circuit modelling and the current interruption process has on amplitude and decay of torsional vibrations in turbine-generator shafts following severe supply network disturbances. A phase-variable model of a synchronous-generator with up to 2 direct-axis and 3 quadrature-axis dampers where fault current is cleared at fault current zeros is employed to calculate generator airgap torque which results from a severe disturbance on the electrical supply. Using airgap torque, effective amplitude of torque excitation acting on the generator rotor for each eigenfrequency is determined by Fourier analysis. Amplitude of torsional vibration at each shaft section for each modal frequency is then calculated. Shaft torque at each shaft location for each modal frequency is thereby deduced. These components, together with the steady-state component (and that due to rotor swing), are summed as absolute values for all modal frequencies to yield approximate peak torque at critical locations along the shaft following each disturbance. Approximate peak shaft torque estimated by frequency domain analysis is compared in some instances with peak torque predicted by solution of exact differential equations. Presented results illustrate amplitude of torque excitation and shaft torques as a function of fault clearing time for L-L-L and L-L high-voltage system short-circuits, and effect reactive power and system resistance has on damping predominant torsional vibrations in the shaft.

Torque measuring system for motor operated valve operators

Abstract: An apparatus and method for isolating certain rotating components within the operator and valve systems and artificially loading those rotating shafts to create and measure torque developed within the valve operator system; and for using the torque measurements to correlate and analyze torque in relation to other valve systems parameters

Closed-loop engine control with feedback torque error compensation

Abstract: A closed-loop engine control system is disclosed in which an engine is controlled to provide power to a load as a function of measured feedback torque. A programmable digital controller modifies the feedback torque by adding to it a synthesized correction torque provided by the product of the engine polar moment of inertia and the engine acceleration. The modified feedback torque is used for either closed-loop torque or horsepower engine control.

Vehicle shock absorber

Abstract: Vehicle shock absorber with a pressure damping valve with a through-flow cross-section varying with the rate of compression. In order to combine the maximum possible damping forces at low compression rates (low speed) with a damping force which increases as little as possible at high compression rates (high speed), the pressure damping valve has the facility for opening considerably more through-flow cross-section in the event of a further increase of the valve lift within a design lift range, which produces a forced kink in the damping characteristic curve as shown in the diagram.

Design for Joint Torque Sensors and Torque Feedback Control for Direct-Drive Arms

Abstract: In a direct-drive arm, motors are directly coupled to their arm linkages without reducers This eliminates some defects of traditional gearing such as backlash, friction and deflection, and therefore enables the drive system to have improved control accuracy The DC motors used for the direct-drive arm, however, have a significant amount of torque ripples and deadband, which limits the control accuracy, particularly for compliance and force control In this paper, a method for the torque feedback control of a direct-drive joint is presented The motor output torque is directly measured by a strain gage sensor built into the motor It is found that closed loop torque control can compensate for the complicated nonlincaritics and improve the overall control accuracy First, the design of the torque sensor is presented The effect of the structural vibration mode which results from the insertion of the flexible torque sensor is analysed, and a design method to place the natural frequency of this mode far above the operating frequencies is shown Torque feedback control using the sensor is discussed The sensor design is verified experimentally, and the control performance using direct torque feedback is evaluated

Dynamic response analysis of 2-R robot with flexible joints

Abstract: In this study the dynamic response of a planar 2-R robot with flexible joints is investigated. Servo stiffness and damping are modeled along with the stiffness and material damping of the drive system. The total system equations are derived and solved for three numerical examples. It is shown that the servo damping plays an important role in the dynamic behavior of the system. Future studies in this subject are discussed.

Power transmission system for vehicles

Abstract: A power transmission system suitable for use in a four-wheel drive motorcar. A torque generated from a power source is directly transmitted to a first axle, and it is transmitted to a second axle via a torque transmission device making use of viscosity of fluid. Between the power source and the second axle is provided torque limiter means for limiting a torque transmitted to the second axle to smaller than a preset value. Even if the torque transmission device should take a locked condition, an excessively large torque would not be exerted upon the respective parts in the power transmission system, and hence a torque transmission system can be made light in weight.

Dynamic instability in permanent-magnet synchronous/stepping motors

Abstract: An analytical study of dynamic instability in hybrid permanent-magnet stepping motors is described, the principal features of which can be applied, more generally, to a wide range of variable-frequency, permanent-magnet synchronous machines. The analysis enables the characteristics of electromagnetic damping torque coefficient against stepping frequency to be obtained for any specified practical value of rotor perturbation amplitude. From these characteristics the overall stability of the motor/drive combination can be deduced. Predicted and experimental results are presented for a 200 steps/rev, bifilar-wound, hybrid-type motor.

Low speed disengageable damper

Abstract: In a damper for a centrifuge for damping the rotor of the centrifuge when the rotor changes rotational velocity through a critical vibrational rotation speed, an improved vibration damper is disclosed. The damper is of the type wherein a conically shaped shaft extension is thrust into engagement with a friction bushing at a circular and central opening to increase shaft section and shift the critical vibrational rotation speed away from the particular critical vibrational rotation speed being traversed. The conical bushing is engaged by a solenoid and translates side-to-side rotor motion to an energy dissipating up and down motion at the solenoid. The improvement disclosed is a conically shaped cone having a negative radius of curvature in section. For small shaft side-to-side excursion (due to small vibration) this conically shaped cone has an initial small slope with respect to the bushing to provide reduced damping of the rotor when small vibration and hence small displacements effect the rotor. For large shaft side-to-side excursion, this same conically shaped cone has a large slope with respect to the low friction bushing which provides for increased displacement of the bushing at large displacements of the rotor. Discontinuities of damping are eliminated. Shaft damping at small excursion is damped with corresponding small damping forces. Shaft damping at large excursion is damped with larger force. Transition of damping between the two extremes is provided with an exponentially increasing damping force having no discontinuities. There results a centrifuge damper that can decelerate a classified sample without appreciable declassification of the sample due to vibration induced diffusion.

Preexisting torque measuring device for threaded fasteners

Abstract: A method and apparatus for accurately determining the previously applied torque to a threaded fastener. Torque is increasingly applied to the fastener and measured periodically. The measurements are digitized and stored in a microprocessor. The torque previously applied is the torque that causes the fastener to breakaway or start to begin to turn. This breakaway point is the torque corresponding to a change in the slope of the applied torque-time relationship. The breakaway point is determined by determining the maximum different value between the measured torque and a mathematical line segment commencing from below the breakaway point and extending to the peak torque applied. The breakaway point (or applied torque) is the torque corresponding to the calculated maximum difference value.

Actuator for friction engaging device

Abstract: PURPOSE: To reduce the size of a device to a relatively low value and to enable fine and rapid execution of response, by providing a torque generating mechanism, converting electric energy to torque, and a torque-thrust force converting mechanism, converting torque of a screw mechanism, a cam mechanism, etc., into a thrust force with the increase in a force. CONSTITUTION: When, based on signals from sensors, detecting a throttle opening, a running speed, etc., a proper electric signal is outputted from a control part, according to the signals, electric energy is converted into torque by means of a torque generating mechanism. The torque is converted into a thrust force by means of a torque-thrust force converting mechanism, and further, the thrust force causes engagement or disengagement of a friction engaging device through a friction engaging press mechanism. In this case, through location of a torque increasing mechanism between the torque generating mechanism and the torque- thrust force converting mechanism, a thrust force is produced. Namely, the engaging force of the friction engaging device can be controlled directly by means of electricity, control is facilitated, and response is improved. COPYRIGHT: (C)1988,JPO&Japio

Electric-motor control drive

Abstract: A control drive having an asynchronous motor with a soft torque/speed characteristic is regulated at discrete constant rotation speeds using a phase-gating controller. The phase-gating angle is a measure of the emitted torque. The torque can be limited and/or the motor MO cut off if a limit value is exceeded, by specifying limit values for the phase-gating angle. The invention is used for control drives.

A Systems Approach to the Torque Control of a Permanent Magnet Brushless Motor

Abstract: Many approaches to force control have assumed the ability to command torques accurately. Concurrently, much research has been devoted to developing accurate torque actuation schemes. Often, torque sensors have been utilized to close a feedback loop around output torque. In this paper, the torque control of a brushless motor is investigated through the design, construction, and utilization of a joint torque sensor for feedback control and through the development and implementation of techniques for phase current based feedforward torque control. It is concluded that simply closing a torque loop is no longer necessarily the best alternative since reasonably accurate current based torque control is achievable.

Hydraulically acting vibration damper with adjustable damping force

Abstract: The invention relates to a hydraulically acting vibration damper with an adjustable damping force for vehicles. The damper comprises a cylinder filled with damping fluid, the interior of which is divided into two working chambers by a piston connected to a piston rod and has adjustable piston damping. For this purpose, there is, in addition to the customary piston damping valves, a bypass passage, the cross-section of which can be varied in a controlled manner. In order to obtain a change in the damping force which is effective over the entire speed range, the bypass passage has a bypass-damping valve connected in series with it, which can be operated by the pressure difference between the working chambers.

Torque control device of internal combustion engine

Abstract: PURPOSE:To reduce fluctuation torque transmitted to a power transmission system and vibration transmitted to an engine support portion by controlling torque which is absorbed or generated by a motor generator according to rotating speed fluctuation information after one rotation. CONSTITUTION:A micro-computer 6 detects fluctuation torque of an internal combustion engine 1 in the form of rotating speed fluctuation, calculates a crank angle and the magnitude of an output current or a field current for switching the operation of a motor generator 5, which is required for the rotating speed variation computed from an output pulse of a crank angle sensor 10 to come to zero, and sends a command value to a torque control portion 7 after an engine 1 makes one rotation. In response to the command, the torque control portion 7 changes the operation of the motor generator 5 to a generator or an electric motor to increase and decrease the output current or the field current. Thus the torque which the motor 5 absorbs or generates works for cancelling fluctuation of torque generated by an internal combustion engine body 2, and as a whole, the torque fluctuation of the internal combustion engine 1 can be restrained.

Vibration damper having an adjustable damping force

Abstract: A vibration damper of simple construction having an adjustable damping force for vehicles, which has controllable bypass channels and enables various damping characteristics on the tension side and pressure side over the entire speed range is created by the present invention. This is achieved in that a slide valve forms two mutually separate and controllable bypass channel systems, as a result of which the tension and compression damping each have one channel system allocated to them.

Flywheel with torsional vibration damping

Abstract: The flywheel for a motor vehicle transmission incorporates damping of torsional vibration. Torque from the crankshaft is transmitted by way of a disc (3), and a damping assembly (13) to a disc (41), which drives the second flywheel half (4) and friction clutch. The damper comprises an annular chamber (51) containing a spring (45) and a viscous medium. Rotational effort is applied to the spring (45) by radial projections (41,49) on the input disc (3). The chamber (51) is closed by the projections (49) except for a narrow gap (54).

Torque damping device for vehicle drive unit - has two=stage damping system between opposing flywheel devices, limiting relative rotation

Abstract: The damping device inserted between the ic engine and the switched transmission system, has two relatively rotatable flywheel devices with a damping medium between them, one device attached to the engine crankshaft and the other coupled to the switched transmisison via a clutch. Two parallel resilient dampers are fitted between the opposing flywheel devices for opposing their relative rotation. Initially the relative rotation is only opposed by one of these dampers over a given angular zone, with both dampers effective over a second angular range. The second damper lies radially within the first damper and it pref. has a higher stiffness.