Abstract: "Velocity Observer" and "Imbalance Observer" circuits are used to control the journals in the magnetic field of an attractive type active magnetic bearing and/or damper. The circuits are characterized by the use of integrators rather than differential components. The velocity observer circuit uses a position feedback loop and a velocity observer feedback loop, both with variable gain, to control the levitation of the journal in the magnetic field. The imbalance observer circuit recreates the journal acceleration directly from the displacement measurement and can be used optionally on-line and off-line to suppress vibrations.

Abstract: The present invention relates to a resonant piston compressor in which a double-sided piston reciprocates within a cylinder and defines a valved compression space on one side of the piston and a balance chamber on its other side. The invention further includes a movable head adjustable between first and second positions to effect a large change in the total volume of the balance chamber between the two positions. In one position, of the movable head an extended balance chamber volume is coupled to the balanced chamber while in the other position of the movable head, the extended balance chamber volume is decoupled from the balance chamber.

Abstract: A linear reciprocating machine has a tubular outer stator housing a coil, a plunger and an inner stator. The plunger has four axially spaced rings of radially magnetized permanent magnets which cooperate two at a time with the stator to complete first or second opposite magnetic paths. The four rings of magnets and the stators are arranged so that the stroke of the plunger is independent of the axial length of the coil.

Abstract: An electrodynamic motor having a flat plunger core arrangement formed out of alternating layers of magnetic and insulating strips clamped together and maintained on respective bearing sleeves which reciprocate on guide members with the gap between stator members.

Abstract: A free-piston reciprocating compressor includes a reciprocating piston disposed within a cylinder such that one end of the piston-cylinder provides for a compression space and the other end of the piston-cylinder provides for a balancing space. The piston is coupled to and reciprocatingly driven by the armature of a linear electrodynamic motor, which armature reciprocates on guide means. The compressor also includes porting means operative to establish a stabilizing gradient sufficient to keep the piston operating at a related fixed mid-stroke position. The motor armature is also coupled to a centering-resonance spring.

Abstract: A coupling for vibration testing comprises a pair of connecting links to be attached to a shaker head and to a driven fixture, respectively. Each of these has an axial passage through it and a convex spherical distal bearing surface. These bearing surfaces face each other. A center element has an axial passage through it and has opposite concave spherical bearing surfaces that face against the convex spherical bearing surfaces of the two connecting links. A low-friction coating or layer, i.e., fiber-reinforced PTFE, is applied to the convex bearing surfaces of the connecting links and provides a low-friction sliding surface against the mating surfaces of the center element. A preload bolt extends through the axial passages of the device and exerts a compressive axial preloading stress which exceeds the maximum vibrational force likely to be encountered.

Abstract: A system for balancing rotating members comprising a laser head which emits a laser shot in response to a laser control signal to remove material from the rotating member. The laser control signal is produced by a computer which is responsive to a plurality of signals representing vibration of the rotating member and influence coefficients from a memory device. The computer applies less than a calculated number of laser shots at each targeted location of the rotating member and then applies this reduced number sequentially to all targeted locations while calculating whether the vibration signals fall below targeted levels and, if so, discontinuing removal of material by the laser.

Abstract: A two piston Stirling engine wherein the pistons are coupled to a common crankshaft via bearing means, the pistons include pad means to minimize friction between the pistons and the cylinders during reciprocation of the pistons, means for pressurizing the engine crankcase, and means for cooling the crankshaft and the bearing means eliminating the need for oil in the crankcase.

Abstract: A tachometer signal conditioner circuit functions to accept a wide range of input signals and produces a digital pulse signal which indicates a gear shaft phase reference position. Tachometer input signals of either a true 1/revolution or an N/revolution signal with a single pulse or N pulses of different amplitude than the other pulses during the same shaft revolution can be used. The circuit comprises tachometer signal conditioner circuitry for amplifying and filtering the input from the tachometer, tachometer signal detector circuitry to produce digital pulses synchronous with the tachometer signal cycles and to detect the occurrence of a tachometer signal with a different amplitude during each 1/revolution or N/revolution period, a blanking signal generator which prevents tachometer signal noise from generating spurious 1/rev pulses during operation in the N/rev mode, and an output driver which produces signals to the remaining signal circuitry and to a front panel indicator lamp.

Abstract: A fiber optic sensor probe system comprises an electromechanical arrangement system which enables a fiber optic probe to lock onto a null point relative to a target which null point represents an in focus condition for the probe relative to the target. A servomechanism feedback circuit maintains the probe in an in focus condition relative to the target if the target moves. A dithering motion is provided to the probe such that, when the electrical output of the probe has a frequency component which is the same frequency as that of the dither, an out of focus condition of the probe relative to the target exists and the servomechanism feedback system operates to correct it. A monochromatic light source is used to eliminate the problem of different spectral components of light having slightly different focal lengths.

Abstract: A resonant reciprocating compressor wherein a reciprocating assembly comprising the movable armature of an electric reciprocating motor and a piston means coupled to the armature is driven cyclically when the electric motor is energized from an alternating current source to compress a working fluid, and including means operatively associated with the reciprocating assembly for producing a stabilizing force gradient in a direction to maintain or restore the reciprocating assembly to a centered operating position.

Abstract: In a resonant piston compressor utilizing a balance chamber to provide a gas spring effect for use in a heat pump arrangement and the like, an adjustable balance cylinder head which adjusts so as to increase or decrease the balance chamber volume so as to increase or decrease the stiffness of the balance chamber, depending upon the mode of operation desired.

Abstract: This invention relates to a detection circuit for use in a servo controlled fiber optic sensor. A low noise signal with an amplitude proportional to the magnitude of the synchronous detection output is produced without the use of filter by a calculation of the average vale of the synchronous detector output signal driving one complete cycle of the dither signal cycle. This value is fed into sample and hold circuitry, which in turn controls the series motor.

Abstract: A system for locating a feature of an object disposed in a frame includes a spot projector for projecting a spot in the general vicinity of the feature and an imaging device with a limited field of view. The spot projector is a precision device which projects the spot towards a preselected location on the frame. When the spot and the feature are in the field of view of the imaging device, the absolute location of the feature is determined from its selective distance to the spot. Provisions are also made for determining depth or relief information about the object.

Abstract: A load support servomechanism circuit controls the armature of a shaker apparatus. The circuit includes a position sensor, peak detectors connected to outputs of the position sensor, an A/D converter connected to outputs of the peak detectors through a switching bank, a power supply and a microprocessor which provides clock, read, write and ready signals and which automatically controls the position of the armature through solenoids operating on an exhaust valve and a pressure valve. Manual operation of the shaker armature is also provided.

Abstract: A linear air compressor having a linear electrodynamic motor which is air cooled and has an increased stroke and accordingly increased output. The working piston is provided with and stroke parting on a push-pull spring provides for centering of the plunger of the motor.

Abstract: A new variable impedance type system is described for measuring a preselected physical parameter such as spacing, displacement, pressure, vibration, etc. A sensor/transducer is positioned to provide the variable impedance. The sensor/transducer is part of a self-oscillatory circuit which produces pulses having a pulse rate proportional to the physical parameter being measured.

Abstract: A proximity sensor includes a bifurcated optic fiber bundle with a face and a projection lens for projecting an image on a target and a feedback control loop for maintaining said face at a preselected distance from the target for tracking. An oscillating device is provided which is disposed in the light path with fixed excursion between the face and the target and which generates an AC component in said sensor signal that is proportional to the deviation of the actual distance from the preselected distance, whereby the error signal is kept near zero.

Abstract: An electro-mechanical shaker apparatus utilizing a novel design is disclosed. The shaker apparatus includes an armature frame which is directly coupled to an armature coil to form an integrated unit. The shortened height of the unit effectively raises telescoping resonant frequencies above the spectrum of test frequencies. The armature frame is comprised of a top plate, bottom plate, and an intermediate section to form a laminated/honey-combed design. The top and bottom plates have a higher modulus of elasticity, while the intermediate section has a lower mass density, which effectively raises bending resonant frequencies above the spectrum test frequencies.

Abstract: A method of determining the displacement of a fiber optic sensor from a target in which a first lens is spaced from the target at a first distance an a second lens is spaced from said target at a second distance which provides the greatest intensity response at said first distance and thereafter spacing said first lens from said second lens to provide symmetrical slope values of response.