Showing papers on "Solenoid published in 1997"

Of flying frogs and levitrons

Abstract: Diamagnetic objects are repelled by magnetic fields. If the fields are strong enough, this repulsion can balance gravity, and objects levitated in this way can be held in stable equilibrium, apparently violating Earnshaw's theorem. In fact Earnshaw's theorem does not apply to induced magnetism, and it is possible for the total energy (gravitational+magnetic) to possess a minimum. General stability conditions are derived, and it is shown that stable zones always exist on the axis of a field with rotational symmetry, and include the inflection point of the magnitude of the field. For the field inside a solenoid, the zone is calculated in detail; if the solenoid is long, the zone is centred on the top end, and its vertical extent is about half the radius of the solenoid. The theory explains recent experiments by Geimet al, in which a variety of objects (one of which was a living frog) was levitated in a field of about 16 T. Similar ideas explain the stability of a spinning magnet (Levitron TM ) above a magnetized base plate. Stable levitation

Accurate position control of a pneumatic actuator using on/off solenoid valves

Abstract: The development of a fast, accurate, and inexpensive position-controlled pneumatic actuator that may be applied to a variety of practical positioning applications is described. A novel pulse width modulation (PWM) valve pulsing algorithm allows on/off solenoid valves to be used in place of costly servo valves. The open-loop characteristic is shown both theoretically and experimentally to be near symmetrical. A comparison of the open- and closed-loop responses of standard PWM techniques and that of the novel PWM technique shows that there has been a significant improvement in the control. A linear process model is obtained from experimental data using system identification. A proportional integral derivative controller with added friction compensation and position feedforward has been successfully implemented. A worst case steady-state accuracy of 0.21 mm was achieved with a rise time of 180 ms for step inputs from 0.11 to 64 mm. Following errors to 64-mm S-curve profiles were less than 2.0 mm. The controller is robust to a sixfold increase in the system mass. The actuator's overall performance is comparable to that achieved by other researchers using servo valves.

Characterization of an inkjet chemical microdispenser for combinatorial library synthesis

Abstract: Solenoid inkjet valves are characterized and implemented in an automated chemical microdispenser, the ChemJet, to be used for combinatorial library synthesis. A novel high-density format for chemical synthesis and assay is also presented. The “ChemSheet” consists of a 48 × 48 array of 8-μL wells, molded as an 8 1/2-in. × 11-in. sheet of polypropylene. The development of the ChemSheet created the need for high-speed, parallel microdispensing. The ChemJet addresses this need by providing the ability to dispense 8-μL volumes of chemical reagents to the 2304 wells of the ChemSheet in under 10 s, with an average reproducibility of ∼2.2%. Results from both quantitative and qualitative characterization of inkjet solenoid valves are presented. Characterization of the ChemJet instrument is also presented.

Hydraulically-actuated fuel injector with direct control needle valve

Abstract: A hydraulically actuated fuel injector includes an injector body having an actuation fluid inlet and a needle control chamber. A hydraulic means within the injector pressurizes fuel in the injector body. The hydraulic means includes an actuation fluid control valve having a solenoid and is movable to open and close the actuation fluid inlet. A needle valve member includes a closing hydraulic surface exposed to pressure in the needle control chamber. A needle control valve, which utilizes the same solenoid, is mounted in the injector body and movable to open and close the needle control chamber to a source of high pressure fluid. The slower response time of the actuation fluid control valve allows for direct control of the fast responding needle valve by a single fast acting solenoid.

Restoration of the DIII-D solenoid

Abstract: The DIII-D tokamak has been operated since June 1995 with constrained ohmic heating capability as imposed by the abandonment of half of it's solenoid system due to a cooling water leak. The solenoid is comprised of "A" and "B" windings with separate multiple power leads to each. The cooling water leak occurred in the lead of the B winding. This leak occurred in a remote area under the DIII-D vessel and is believed to be caused by magnetic forces developing cyclic bending loads on the conductor. Visual inspection of the lead using flexible bore scopes indicated that the structural fiberglass overwrap intended to band the supply and return leads into a primary-force canceling group had failed allowing individual conductors to become inadequately supported against bending loads. The overwrap failed as a result of poor epoxy encapsulation of the lead which was manufactured in 1978. Inspection of the A lead confirmed no overwrap failure and that the vacuum encapsulation of the A lead was proper and to specification. In order to continue operations, it was decided to abandon the B winding of the solenoid and operate under reduced (5 V-sec) capability. An in-situ repair approach was mandated by the extensive and lengthy effort required to disassemble, repair, and reassemble the tokamak. Access from outside the tokamak was severely limited. A plan to repair the damaged lead was developed and implemented over a 10 month period. This paper describes the repair of the solenoid lead. A VCR video tape of these remote installation efforts has been assembled.

Load demand throttle control for portable generator and other applications

Abstract: The throttle of an engine in an engine driven generator system operating subject to a wide and rapidly variable load, as in supplying current to a welder, is operated such that control signals are sent to a throttle actuator for adjusting the engine throttle position in response to load changes. The throttle actuator may be a solenoid pulling against a spring in accordance with the average current through the solenoid coil. In this embodiment, the processor causes pulse width modulated signals to be applied across the solenoid coil with throttle position changes being reflected in changes to the width of the pulses, such changes in the pulse width being delayed for at least the predetermined time since the last preceding adjustment to the throttle. Alternatively, the throttle actuator may be a stepper motor which is stepped by throttle position change signals from a processor which monitors engine speed and generator load to determine whether the throttle should be adjusted and, if so, in which direction and to what extent for optimum response.

Fuel injection valve and method of manufacturing the same

Abstract: A fuel injection valve has a single pipe member made of composite magnetic material which can be processed to form ferro-magnetic structures and non-magnetic structures. A magnetic fuel connector, a magnetic valve body, a nonmagnetic intermediate pipe are formed in the single pipe member. An electromagnetic solenoid is disposed around the intermediate pipe, and a needle valve is disposed in the valve body. A magnetic stationary core is disposed inside the fuel connector, and a magnetic movable core is disposed inside the valve body in a magnetic circuit composed of the solenoid, the fuel connector, the stationary core and the valve body.

Rapid computation of static fields produced by thick circular solenoids

Abstract: A straightforward method is proposed for computing the magnetic field produced by a circular coil that contains a large number of turns wound onto a solenoid of rectangular cross section. The coil is thus approximated by a circular ring containing a continuous constant current density, which is very close to the real situation when wire of rectangular cross section is used. All that is required is to evaluate two functions, which are defined as integrals of periodic quantities; this is done accurately and efficiently using trapezoidal-rule quadrature. The solution can be obtained so rapidly that this procedure is ideally suited for use in stochastic optimization. An example is given, in which this approach is combined with a simulated annealing routine to optimize shielded profile coils for NMR.

Status report on a dc 130-mA, 75-keV proton injector

Abstract: A 110-mA, 75-keV dc proton injector is being developed at Los Alamos. We use a microwave proton source coupled to a two solenoid, space-charge neutralized, low-energy beam transport (LEBT) system. The ion source produces 110-mA proton current at 75 keV using 600 - 800 W of 2.45 GHz input discharge power. Typical proton fraction is 85-90% of the total extracted ion current, and the rms normalized beam emittance after transport through a prototype 2.1 m LEBT is 0.20 ({pi}mm-mrad). Beam space-charge neutralization is measured to be > 98% which enables the solenoid magnetic transport to successfully match the injector beam into a radio-frequency quadrupole (RFQ). Beam simulations indicate small emittance growth in the proposed 2.8 m low-energy demonstration accelerator (LEDA) LEBT. The LEBT also contains beam diagnostics, steering, and a beam deflector for variable duty factor and accelerator fast protect functions. The injector computer controls and reliability status are also discussed.

Apparatus and method for high-speed transfer and centering of wafer substrates

Abstract: An apparatus for centering and gripping semiconductor wafers. A solenoid is used to actuate two or three curved contacts. Power to the solenoid, and position information from the solenoid is transmitted along a pair of wires. To center the wafer, the solenoid is actuated and the contacts move radially towards the center of the wafer. The contacts grip the edge of the wafer and a pulse-width-modulation signal is used to determine solenoid position as a function of back electromotive force value or waveform. During handling, the contacts hold the wafer such that the wafer does not move relative to the apparatus.

Solenoid driver and method for determining solenoid operational status

Abstract: A solenoid driver (10) capable of detecting the operational status of a solenoid (12) including the position of an armature within a solenoid coil and an operational method. The solenoid driver (10) generates a first solenoid current within the solenoid (12) and measures a first decay time t1. The first solenoid current is insufficient to pull the armature into the coil of the solenoid (12). A comparator circuit (22) continuously monitors the solenoid current and initiates a timer within a counter circuit (34) to compute the first current decay time. A second solenoid current is generated within the solenoid (12) that is sufficient to pull the armature into the coil of the solenoid (12). The second solenoid current is turned off and a second decay time t2 is measured. The decay times are stored in storage registers (R1, R2) within a controller (36). The controller (36) compares the measured decay times with stored values and outputs the armature position information over a communications bus (34).

Thin film heads having solenoid coils

Abstract: A low-noise toroidal thin film head ("TFH") device has low coil resistance and inductance, especially suitable for very high magnetic recording areal densities and channel frequencies. The length of a toroidal coil turn is only about 20-30% that of the length of an average turn in the conventional planar spiral coil design. This allows either reduction of the device thermal noise (by about 6 dB) and/or increase of the device operational frequency bandwidth (by a factor of 3-5). The toroidal coil coupling efficiency between each turn and the magnetic core is practically 100%, thereby improving the write and read-back efficiencies. In one embodiment a non-via large back-closure contact area is provided between the bottom and top magnetic poles along their entire back-side width, and all other open branches and loose ends in the magnetic circuit are eliminated. The magnetic core has a gradual, smooth toroidal (or a horse-shoe) shape with no loose ends, nooks, crevices, or sharp corners. The larger back-closure contact area decreases the magnetic core reluctance and improves the device efficiency. Utilization of a soft non-magnetic seed-layer, such as gold, eliminates interference noise due to the conventional magnetic (NiFe) seed-layer. Slight mechanical texturing (scratching) of the seed-layer along the intended easy axis helps to define and induce strong magnetic uniaxial anisotropy in the plated magnetic poles. All these features facilitate significant reduction of Barkhausen and other sources of device noise. Embodiments include conventional TFH's, Planar TFH's, Pinched-Gap TFH's, and various versions of Magnetoresistive (MR) TFH's.

The design and operation of the SPHEX spheromak

Abstract: We describe the design and operation of the SPHEX spheromak device and present an overview of its behaviour. The plasma is formed by ejection from a magnetized Marshall gun, and can be sustained as long as the gun is energized. The plasma is divided into the annulus comprising the closed toroidal flux, linked with the open flux forming the central column. The column current is driven directly by the central gun electrode, and the toroidal current in the annulus is driven indirectly by a mechanism associated with a coherent n = 1 oscillation of the column. The configuration exemplifies the operation of the process of relaxation to a state of minimum magnetic energy, which leads to magnetic configurations similar to those observed; to sustain these configurations requires some mechanism of toroidal current drive. Associated with this is the amplification of the poloidal flux, which is typically a factor of about five larger than the flux generated by the gun solenoid; the constancy (to a first approximation) of this factor plays a controlling role in spheromak behaviour. In standard operating conditions there is a `hard' limit, set by the solenoid flux, on the current carried by the column; any current driven by the external circuit above this apparently does not emerge from the gun. Evidence is presented that the column current is carried largely (> 50%) by accelerated ions with energy up to the gun voltage ( for a typical gun current of 60 kA). These ions are poorly magnetized and can escape across the magnetic field to the wall, a likely mechanism for the observed `loss' of current. Hydrogen is the normal operating gas: other gases ( and He) have been used, but the current drive is found to be less effective than in , with lower toroidal current maintained in the annulus.

Cordless hydrocarbon fuel heated hairdryer

Abstract: A cordless, hydrocarbon fuel powered hairdryer (1). The invention incorporates a novel electronic control system which evaluates the thermal and electrical conditions within the hairdryer during its operation. Two fuel flow valves are provided. The first fuel flow valve is mechanically actuated and opens and closes the valve in the hydrocarbon fuel cartridge. The second fuel flow valve is a solenoid valve (37) that cannot open without a predetermined voltage being supplied. Application of the predetermined voltage will allow gas to flow through this second valve and into the area where the fuel is ignited. Only when both valves (the mechanical and the solenoid) are open, can fuel flow. A microcontroller (fig. 5) monitors the temperature conditions in the combustion area, and controls system conditions such as power to the solenoid valve and the fan motor (13) to prevent uncombusted gas from building up and presenting a safety hazard.

Automatic hydronic zone valve and electric controls therefor

Abstract: An automatic and improved electrical control for an automatic hydronic zone valve including a switching device for opening and closing solenoid valves based on adjustable temperature settings. Specifically, the preferred system involves a solenoid-controlled valve in which the solenoid is activated and deactivated by an electrical control circuit which relies on an external thermostatic switch and an internal relay to open and alternately close the following sub-circuits: a solenoid control sub-circuit which is directly connected to the valve solenoid, an AC to DC converter, relay control circuitry, a relay switch connection to a water circulator system and LED sub-circuits indicating power status and/or activation of the heating system. The solenoid control sub-circuit includes a series thermistor and a parallel capacitor to, respectively, slow the provision of electrical current to the solenoid to avoid "water hammer," and, quiet the electronic hum of the solenoid. Moreover, the current invention also involves simplified wiring such that only two wires each are necessary for thermostat connection, for power supply connection and for water circulator connection. But for these three external connection sites, all the other control circuit elements are disposed in a single compact unit, preferably housed on the solenoid valve itself.

Diagnostic technique for Zeeman-compensated atomic beam slowing: Technique and results

Abstract: We have developed a diagnostic tool for the study of Zeeman-compensated slowing of an alkali-metal atomic beam Our time-of-flight technique measures the longitudinal velocity distribution of the slowed atoms with a resolution below the Doppler limit Furthermore, it can map the position and velocity distribution of atoms in either ground hyperfine level inside the solenoid without any devices inside the solenoid The technique reveals the optical pumping effects and shows in detail how the slowing within the solenoid proceeds We find for Na that most atoms in the chosen hyperfine state are decelerated in the slowing process The width of the velocity distribution is determined mainly by inhomogeneities in the slowing laser beam Using the central most uniform part of an expanded laser beam, the width is reduced to 25 m/s, corresponding to 32 mK Finally, we discuss and show a method to produce a beam with two-velocity components for the study of head-tail low-energy collisions

Compensation of the radial magnetic field component of solenoids wound with anisotropic Bi(2223)Ag tape

Abstract: The critical current of a solenoid made of Bi(2223)Ag tape with a high anisotropy in the critical current - magnetic field characteristic at 77 K is determined in particular by the radial component of the magnetic field, which is large close to the coil flanges. The original idea of utilizing supplementary (e.g. copper) windings to compensate partially the undesired radial magnetic field component of the high-temperature superconducting (HTS) coil is described. The results of extensive numerical calculations on the model coil indicate that an increase of the critical current of more than 50% can be expected.

Solenoid operated clutch for powered sliding door

Abstract: A clutch (10) (e.g. for a powered sliding door) comprises a gear (24) axially shiftable from a disengaged position to an engaged position by a solenoid (58) actuated reciprocating means (56) counteracting a biasing means (38).

Method and apparatus for sensing armature position in direct current solenoid actuators

Abstract: An apparatus detects a position of an armature within a solenoid coil by superimposing a fixed frequency sensing signal onto the coil driver signal. The combined signal is applied to the solenoid coil and an alternating current component varies with changes in inductance of the solenoid coil that result from position changes of the armature. A current sensor produces an output signal indicating a level of current flowing through the solenoid coil and a filter extracts the alternating component of that output signal that results from the sensing signal. A position circuit determines the position of the armature from an output from the filter.

Pulse width modulated drive for an infinitely variable solenoid operated brake cylinder pressure control valve

Abstract: A pulse width modulated drive circuit drives a solenoid operated valve in response to an input voltage signal from a control apparatus. The solenoid operated valve includes a coil that is energizable in response to energy received from the pulse width modulated drive circuit. The pulse width modulated drive circuit includes a pulse generator stage and an output stage. The pulse generator stage receives the input voltage signal from the control apparatus and a feedback signal from the coil which ultimately combine to form a control voltage in response to which the pulse generator stage generates a pulse width modulated signal whose duty cycle depends on the control voltage. The output stage receives the pulse width modulated signal from the pulse generator stage and generates in response thereto a pulse width modulated output signal across the coil. The pulse width modulated output signal has pulse width generally proportional to the control voltage and carries energy from a source of energy. The pulse width modulated output signal energizes the coil thereby enabling the coil to generate a force generally proportional to the average current carried by the pulse width modulated output signal.

Apparatus to check calibration of mass flow controllers

Abstract: A calibration apparatus is applied to a gas control panel (46) that uses mass flow controllers (70,98,118) to control the flows of different gases to a processing chamber (42). The gas control panel (46) includes a mass flow meter (150) mounted on the gas control panel (46). The mass flow meter (150) is connected between pre-existing and unused gas valves (152, 156) on the gas control panel (46) in place of a mass flow controller that is also otherwise unused. The meter input valve (152) for the mass flow meter (150) is in fluid communication with the mass flow controllers (70, 98, 118). The input and output meter valves (152, 156) are connected to respective pre-existing solenoids (154, 158) which in turn are connected to a gas flow control (48). A final valve solenoid (82) controls a final valve (80) which is also in fluid communication with the mass flow controllers (70, 98, 118) and routes the gases to the processing chamber (42). The calibration system includes a switching device (162) mounted on the gas control panel (46) and connected between the output (163) of the final valve solenoid (82) and a control input (81) of the final valve (82). The switching device (162) has a control input (164) connected to an output of the meter input valve solenoid (154). Thus, in one state, the meter input solenoid (154) inhibits gas flow through the processing chamber (42) and permits gas flow from the mass flow controllers (70, 98, 118), through the mass flow meter (150) in order to check the calibration of the mass flow controllers. In an opposite state, the meter input solenoid (154) inhibits gas flow through the mass flow meter (150) and permits flow to the processing chamber (42).

Solenoid frame and method of manufacture

Abstract: Apparatus for method of manufacture for a solenoid frame is disclosed A preferred embodiment of the present invention utilizes a single piece configuration having interlocking tabs and a locking mechanism for securely fastening the frame end pieces, and further including coil-assembly-retention locks for securely engaging the solenoid coil

Electronic gas regulator

Abstract: A gas regulator has a has an internal gas chamber and a solenoid valve that controls gas flow into the clamber. A pressure monitor monitors the pressure in the chamber and controls the operation of the solenoid valve to produce a desired pressure in the chamber. The solenoid control signal is a pulsed signal with a variable pulse width, frequency or both. The pressure maintained in the chamber may itself be varied by altering the set point pressure, for example according to the operating parameters of an engine.

Remote controlled carpet cleaner

Abstract: A remote controlled carpet cleaner includes a rectangular outer support frame of structural steel. A gasoline engine drives a vacuum pump and through a pulley and belt assembly is also powers a liquid pump. The exhaust gas from the engine is directed to a heat exchanger which is used to heat water which is pumped through the heat exchanger by the liquid pump. A liquid injector allows carpet cleaning chemicals to be mixed with the water as it enters the pump. The liquid injector is connected to a plurality of solenoid valves. Each solenoid valve is connected to a tank containing a carpet cleaning chemical. When a solenoid valve is opened, a specific carpet cleaning chemical in drawn into the liquid injector and mixed with the water entering the pump. The opening and closing of the solenoid valves is controlled by servo motors operated by a radio controlled receiver. The operator carries a belt mounted transmitter unit which transmits signals to the receiver to thereby direct the opening and closing of the solenoid valves and thus the carpet cleaning chemical to be dispensed. The transmitter unit includes a "lockout" feature to prevent the accidental dispensing of the wrong chemical. The remote controlled carpet cleaner offers a substantial increase in productivity by offering an operator the ability to remotely control and dispense required cleaning chemicals without making repeated trips between the cleaning site and a supply truck.

Latching coil valve

Abstract: A latching coil valve device is provided, comprising a body providing an inlet and an outlet; an actuatable valve unit connecting said inlet to said outlet, and latching mechanisms for latching the actuatable valve unit in open or closed positions, respectively. The actuatable valve unit comprises a solenoid and a pilot operated valve comprising a primary valve member and a pilot valve member. The solenoid comprises a coil assembly and a plunger assembly. Energizing the coil of the solenoid moves the plunger to open and close the valve. The latching mechanism for latching the actuatable valve unit in the open position comprises a permanent magnet and the latching mechanism for latching the actuatable valve unit in the closed position comprises a coil spring. Only a momentary pulse of voltage needs to be applied to the coil of the solenoid in order open or close the valve. Once in the opened or closed positions, the permanent magnet or the coil spring, respectively, latches the valve. Means to tune the characteristics of the voltage pulse required to open and close the valve are provided by an adjustment mechanism for adjusting the position of the permanent magnet with respect to the plunger.

Fuzzy PWM control of the positions of a pneumatic robot cylinder using high speed solenoid valve

Abstract: In the study, instead of using expensive servo valves, three inexpensive high-speed solenoid valves were adopted and a fuzzy PWM controller was designed to control the linear and rotational positions of a pneumatic robot cylinder. The modified differential PWM method is proposed to eliminate the dead zone and to improve the nonlinear characteristics between the pressure difference of the cylinder and the duty ratio of the PWM control signal. The experimental results have shown that the servo pneumatic system with the proposed fuzzy PWM controller exhibits good performance.

Shape Optimization of Solenoid Actuator Using the Finite Element Method And Numerical Optimization Technique

Abstract: This paper presents shape optimization of moving core type solenoid actuator driven by DC source. 3-D axisymmetric finite element method (FEM) is used for the electromagnetic field analysis and saturation effect of the magnetic material is considered. The mechanical dynamic equation and electrical circuit equation are also coupled. In the dynamic characteristic by FEM, we adapt a moving line technique to save computation time and to perform the process efficiently. Among the optimization algorithms, sequential quadratic programming (SQP) is carried out for the shape optimization. A good performance of optimized solenoid actuator has been verified through the experiment.

Automatic stop-starting device for engine

Abstract: PROBLEM TO BE SOLVED: To reduce wear of a pinion and a ring gear so as to improve durability of a starter by applying a current to a pinion mesh control solenoid to mesh the pinion with the ring gear during automatic stop of an engine in a device for automatically stopping the engine. SOLUTION: In an automatic stop state of an engine 1 automatically stopped when a specified condition is materialized, when a rotation sensor 4 senses engine speed being zero, a current is applied to a pinion mesh control solenoid 13. At this time, voltage applied to a solenoid 13 is gradually increased to mesh a pinion slowly with a ring gear. When an engine starting condition is materialized afterwards, a current is applied to a starter motor 14 to start the engine 1, and when a rotation sensor 4 for detecting the rotating speed of the engine 1 detects rotating speed that can be judged as the completion of start of the engine 1, current application to the pinion mesh control solenoid 13 and starter motor 14 is stopped.