Showing papers on "Damper published in 1985"

Distributed Piezoelectric-Polymer Active Vibration Control of a Cantilever Beam

Abstract: An active vibration damper for a cantilever beam was designed using a distributed-parameter actuator and distributed-parameter control theory. The distributed-parameter actuator was a piezoelectric polymer, poly (vinylidene fluoride). Lyapunov's second method for distributed-parameter systems was used to design a control algorithm for the damper. If the angular velocity of the tip of the beam is known, all modes of the beam can be controlled simultaneously. Preliminary testing of the damper was performed on the first mode of the cantilever beam. A linear constant-gain controller and a nonlinear constant-amplitude controller were compared. The baseline loss factor of the first mode was 0.003 for large-amplitude vibrations (± 2 cm tip displacement) decreasing to 0.001 for small vibrations (±0.5 mm tip displacement). The constant-gain controller provided more than a factor of two increase in the modal damping with a feedback voltage limit of 200 V rms. With the same voltage limit, the constant-amplitude controller achieved the same damping as the constant-gain controller for large vibrations, but increased the modal loss factor by more than an order of magnitude to at least 0.040 for small vibration levels.

Reduction seismic response with heavily-damped vibration absorbers

Abstract: It is shown that two of the damping ratios of certain systems composed of a building and a small attachment in resonance are given by the average of the damping ratios of the two independent components. Based on this fact and the fact that the seismic response of a building can always be reduced by increasing its damping, it is demonstrated that the attachment of a small heavily-damped system in resonance can increase the damping of a building and reduce thus its response to earthquake excitations. Numerical solutions are presented to confirm the demonstration, and recommendations are given to calculate the parameters of such systems.

Vehicular suspension control system with variable damping characteristics depending upon road condition and vehicle speed

Abstract: A suspension control system for automotive vehicles automatically adjusts the damping strength of variable shock absorbers or other dampers in accordance with road surface conditions. The sensor signal reflects vertical displacement of the vehicle body from the road surface. The sensor signal is compared to a corresponding reference level which is variable depending upon a vehicle speed. The results of comparison give an indication of the degree and scale of irregularities in the road surface. The comparison information is sent to a suspension system controller which causes actuation of the shock or other dampers absorbers to a stiffer mode of operation when road surface roughness requiring harder suspension is recognized.

Clutch disc for a motor vehicle friction clutch

Abstract: The clutch disc for a friction disc clutch has a hub with external toothing engaging an internal toothing of a hub disc with predetermined rotational play. Axially on both sides of the hub disc, there are arranged side discs of an under-load vibration damper. Damper springs of an idling vibration damper are seated in windows of the hub disc radially inwardly of damper springs of the under-load vibration damper. The idling damper springs are coupled with the hub through side discs. The side discs are arranged axially on both sides of the hub disc and coupled non-rotatably with the external toothing of the hub. For the connection of the ends of the idling damper springs with the side discs, separate tabs formed on the side discs are provided. The components of an under-load friction damper can be arranged within or radially outwardly of the region defined by the under-load damper springs. Radially within the region of the under-load damper springs, at least one thrust ring is provided which transmits the force of an axially acting spring of the friction damper and/or centers the hub disc in relation to the side discs of the under-load vibration damper. The idling damper springs are seated in windows which are open to the windows of the under-load damper springs.

Hysteretic dampers in base isolation: Random approach

Abstract: A method of random vibration analysis of base isolated structures with hysteretic dampers is employed. The hysteretic restoring force is modelled by a nonlinear differential equation. The equations of motion for shear type structures are linearized in closed form. Nonstationary response statistics for evolutionary nonwhite excitation are determined by solving the associated Lyapunov matrix differential equation. An optimization study which is based on the stationary response is also presented.

Frictionless hydraulic damper and damper-snubber

Abstract: A frictionless hydraulic damper including a cylinder having end walls mounting the opposite ends of a shaft with a clearance in labyrinth seals, bellows seals between each end wall and the portions of the shaft extending beyond each end wall, a piston head on the shaft within the cylinder, hydraulic fluid in the cylinder and in both bellows seals, an orifice construction located relative to the piston head for permitting flow of hydraulic fluid past the piston head to produce damping, and a conduit in the shaft for effecting communication between the two bellows. The damper as described above also functions as a snubber by including a valve construction which selectively closes the orifice construction.

Control arrangement for the cooling air of air-liquid-cooled internal-combustion engines, particularly motor vehicles

Abstract: A control device for the flow of cooling air through an air-liquid radiator of an internal combustion engine comprising a fan frame mounted between the radiator and the fan and being part of a noise damper of the engine. A spring curtain is arranged in the fan frame between the radiator and the fan and isolates the noise damper of the radiator, except when the engine reaches high operating temperatures, which prevents the radiator from absorbing power and the engine from being directly air cooled, thus reducing the prewarming time of the engine.

Effects of friction dampers on aerodynamically unstable rotor stages

Abstract: Attention is given to the physical concepts and mathematical techniques useful in the analysis of the stabilizing effect of friction on aerodynamically unstable rotor stages. Results are presented for three-, four-, and five-bladed disks. In the present multidegree-of-freedom model of an aerodynamically unstable rotor stage, a harmonic steady state solution due to the friction dampers may be either a stability limit, a stable cycle limit, or neither. A criterion is established in the form of an energy function which determines whether the solution is a stability limit. In the event that the initial displacement and velocity exeed those associated with the steady state solution corresponding to a stability limit, the reponse becomes unbounded.

Divided fly-wheel

Abstract: The divided fly-wheel comprises a first fly-wheel (7) for securing through first screws (5) to the crank-shaft (3) of an internal combustion engine and a second fly wheel (17) mounted rotatably through a bearing (15) on a bearing extension (9). The bearing extension (9), independently of the screws (5) holding the first fly-wheel (7) on the crank-shaft (3), is screwed through additional screws (11) either on the fly-wheel (7) or on the crank-shaft (3). A torsional vibration damper (19) couples the second fly-wheel (17) rotationally elastically with the first fly-wheel (7). The torsional vibration damper (19) forms a construction unit separate from the first fly-wheel (7) which can be subjected to an operational test with or without the bearing extension (9). The first fly-wheel (7) separate from the torsional vibration damper (19) renders possible a test run of the internal combustion engine before the fitting of the torsional vibration damper (19) and the second fly-wheel (17).

Mechanism for opening and closing a lid

Abstract: A mechanism for opening and closing a lid is disclosed, which includes a rotary damper and an auxiliary rotary damper. An input gear of the rotary damper is in mesh with an output gear of a lid. An input gear of the auxiliary rotary damper is in mesh with the output gear of the lid or the input gear of the rotary damper. Thus, the lid can be sufficiently braked during the opening and closing operations.

Multi-use damper

Abstract: An air damper having a housing, a strut mounted across the housing, a pair of damper panels hinged on the strut, and swingable between open and closed positions, an adjustable control above the strut, and, linkage on the upper side of each panel extending to the control to cause the panels to swing from one position to the other.

Automotive air conditioning system with automatic control of refrigerator compressor capacity and heater air mixing damper

Abstract: An automotive air conditioning system has refrigeration devices, heating devices and a single chip microcomputer. The refrigeration devices include a variable displacement refrigeration compressor drivingly connectable by an electromagnetic clutch to an automotive engine and a refrigerant evaporator disposed in an air duct, through which air is caused to flow by a blower. The heating devices include a heater core disposed downstream of the refrigerant evaporator, through which heated air is caused to flow, and an air mixing damper which regulates the quantity of air to be introduced into the heater core. A condition relating to the air conditioning operation such as the temperature of the vehicle is detected by a sensor. The microcomputer receives the signals from the sensor, calculates a required injection temperature, compares the required injection temperature and a preset standard temperature, a lower standard temperature and a higher standard temperature and produces operating signals. The operating signals manage the connection of the electromagnetic clutch, vary the displacement of the refrigeration compressor, regulate the degree of opening of the air mixing damper and control the rotating velocity of the blower.

Fire damper actuator

Abstract: An electrically-operated fire damper actuator is disclosed which is adapted to operate an associated fire damper having louvers movable between opened and closed positions, with the damper or the actuator including a closing spring which urges the louvers to the closed position. The present actuator is configured to open the louvers in opposition to the closing spring, and maintain the damper in an opened condition against the action of the closing spring, while permitting the damper to close in the event of loss of power to the actuator. The actuator comprises an electric motor which operates through a multi-stage gear reduction unit for opening the louvers in opposition to the closing spring, and further includes an electric brake operatively connected to the motor rotor shaft for maintaining the damper louvers in the opened position. The present actuator further includes a one-way clutch mechanism with the gear reduction unit for avoiding damage to the reducing gears as the damper louvers move to the fully closed position under the action of the closing spring.

Control system for hydraulic dampers

Abstract: A control system for controlling the damping force of a plurality of hydraulic dampers, each of which includes a damping force producing mechanism; a damping force adjustment members for adjusting the effective passage area of an oil passage in the damping force producing mechanism; and an actuator connected to the damping force adjustment member, comprises an indicator circuit for indicating the adjusted and en-route conditions of at least one damping force producing mechanism; an electric power supply circuit for supplying electric power to respective actuators; and the power supply circuit being provided with an inhibiting circuit for inhibiting the supply of power to an actuator associated with a damping force adjustment member which has already been adjusted, through a part of the power supply circuit associated with a damping force adjustment member which has yet not been adjusted.

A Model Analysis of Tire Behavior Under Vertical Loading and Straight‐Line Free Rolling

Abstract: A structural analog, consisting of a flexible circular ring under tension with a nest of radially arranged linear springs and dampers, is developed as a pneumatic tire model. The model is concerned with the prediction of the tire's vertical load‐deflection characteristics and its free rolling resistance. The mathematical formulation of the boundary of the model's region of contact with a smooth hard surface is based on approximations made using the theory of a tensioned string supported by an elastic foundation. Forces developed within the contact region are computed from geometrical considerations. The model's ring tension and radial foundation stiffnesses, as related to the tire's inflation pressure, are obtained experimentally by performing contact patch length measurements and static point‐load tests on the specific tire modeled. Further, by prescribing a loss factor in the radial dampers, the model's free rolling resistance characteristics may be computed. Experimental verification conducted...

Air conditioning system

Abstract: In an air conditioning system, a damper unit disposed in the middle of a circulating duct is controlled so that a throttle valve of at least one of air quantity regulating devices for controlling incoming outside air quantity and exhaust air quantity is fully open, and that the quantity of air passing through the device whose throttle valve is fully open is equal to a set air quantity. The control system for the damper unit is so-called floating control system that is responsive to the control conditions. If none of the throttle valves of the devices is fully open, then there must be too great a pressure difference to pass the set quantity of air through all the devices. Accordingly, the excessive pressure applied to the devices can be lowered to a proper level by driving the damper unit in an opening direction, thereby reducing pressure loss between the discharging and charging blowers. If the throttle valve of at least one of the devices is fully open, and if the passage air quantity is smaller than the set air quantity, then the pressure applied to the devices must be too small to pass the set quantity of air. Accordingly, the insufficient pressure applied to the devices can be increased to the proper level by driving the damper unit in a closing direction, thereby increasing the resistance between the discharging and charging blowers.

Air supply nozzle

Abstract: A ventilating or air supply nozzle for panes, especially windshields, and at least one portion of the interior of a passenger vehicle or a driver's cab The nozzle has an air inlet connection for fresh air and/or recirculated air, and an air outlet opening The nozzle also includes a swivel damper which is pivotably mounted about an axis within a housing, and is provided with curved guide elements or deflectors In order to be able to rapidly deice the windshield, the plane of the air outlet opening extends at an obtuse angle relative to the axis of the air inlet connection The width of the free cross-sectional area of the air outlet opening is at least as great as the width of the cutting plane of the projection of the air inlet connection with the plane of the air outlet opening A housing portion which is in the shape of a circular arc essentially covers the obtuse angle The pivot axis of the swivel damper is disposed on that side disposed across from the housing portion

The Damping Capacity of a Sealed Squeeze Film Bearing

Abstract: The advantages of incorporating an open-ended or weakly-sealed squeeze-film bearing in a flexible support structure simulating an aero-engine assembly were examined. Attention is given to empirically modelling the hydrodynamics of the more usual tightly-sealed squeeze-film bearing, with a view to assessing its damping performance.

Tuned mass damping system and method

Abstract: A damping system for attenuating the transverse oscillation of a structure caused by external forces having a countermass attached to the structure by a spring and a coulomb damper. The parameters of the damping system are chosen so that the natural frequency of the damping system matches the natural frequency of oscillation of the structure.

Hydraulic shock absorber (damper)

Abstract: In a single-tube shock absorber (20) or twin-tube shock absorber (30), the various chambers (4, 5; 24, 25, 26) are connected to one another by connections (8, 16; 28, 29), of which there are preferably eight, the passage through which is controlled by solenoid valves (9/11; 30/34; 31/35). Their magnets (11, 19; 34, 35) can be controlled individually or jointly by means of a closed-loop or open-loop control circuit to take account of specified driving conditions. It is possible to change the damping constants of the shock absorber in a fraction of a second.

Control of dampers for vehicle suspension

Abstract: In a vehicle damping system a damping element provided between a wheel of the vehicle and the vehicle structure comprises a working cylinder (5) for receiving damping fluid and a piston (8) which divides the cylinder (5) into an upper chamber (6) and a lower chamber (7). The chambers (6) and (7) are connected together through an electronically controlled damping valve 19 controlled by an electronic circuit in response to signals from sensor. The sensor may measure damping force, velocity, acceleration, temperature or frequency. Alternatively, as shown, piston travel is sensed by a capacitor 29 within the cylinder and this signal is used to control the valve 19.

Pneumatic spring and damper unit

Abstract: It is a pneumatic spring-damper unit with a cylindrical housing (5) which is closed off by a ceiling (6) and a bottom (7) and which is provided with a first connection (11), one in this housing (5 ) displaceably guided piston (8), which divides the housing (5) into a damper space (2) that increases in compression and a damper space (3) that decreases in compression, a throttle element that is arranged in the piston (8) and can flow through in two directions ( 4), in the piston (8) rigidly fixed and through the bottom (7) of the housing (5) and through a spring chamber (1) guided piston rod (9), at the end of which a second connection (10) is arranged, one between the housing (5) and a part connected to the piston rod (9) arranged rolling bellows (14), which seals the spring space (1), which becomes smaller as the spring deflects, and a lockable ventilation duct (24) leading out of the housing (5). So that in this spring-damper unit the pressure controlled by a level switch in the housing is partially maintained even when fully relieved, the ventilation channel opens into the damper chamber (2), which becomes smaller as it springs out, and is arranged in such a way that it is in the extended state of the unit a piston (8) or an element (25) cooperating with the piston is closed.

Electromagnetic vibrations damper

Abstract: The present invention relates to a vibrations damper mounted between two mechanical members subjected to vibrations and comprising a body 3 delimiting a chamber 6 filled with fluid and connected, elastically or telescopically, by means of attachment components 1, 2 to the said mechanical members. The damper according to the invention is characterised in that it comprises an electromagnetic driver 4 provided with at least one coil 41 supplied with electric current and capable of creating a magnetic field in the fluid formed by a mixture of liquid with hydraulic characteristics and particles made from a magnetic material so as to have a viscosity which is adjustable via the effect of the magnetic field and so as thus to control the damping. The damper according to the invention applies particularly to the elastic suspension of heat engines of vehicles on their support chassis.

30 MVA superconducting synchronous condenser: Design and it's performance test results

Abstract: 30 MVA superconducting synchronous condenser has been designed, fabricated, and tested successfully. The test suggested that the new approaches applied to the 30 MVA machine were reasonable. The superconducting field winding composed of six Nb-Ti and two Nb 3 Sn coils, supported in torque-tube slots by wedges, was excited up to the rated operating current without training. The amplitudes of the rotor vibration were small and special balance at cryogenic temperature was not needed. In this paper, the studies on the key design aspects, namely, superconducting field winding, rotor structural materials, and rotor structures including the connection means between torque-tube(cold) and damper(warm) are described together with the experimental verifications. Moreover, the stator design and the electro-magnetic design including an analysis of the operational performance with regard to double damper system are presented. Machine constants obtained from the theoretical investigations using three-dimensional electro-magnetic field calculations are in good agreement with test results.