Abstract: A gasket for watertight/airtight sealing of individual-acting movable structural closures (such as shipboard doors, hatches and scuttles), featuring utilization of silicone rubber material in a specifically proportioned rectangular-parallelepipedoid shape having two 45.degree. chamfers and a lengthwise intermediate semicylindrical groove. The gasket's superior sealing properties derive from its configuration and composition as well as its resultant unsusceptibility to permanent set. The gasket is softer and hence easier and quicker to install, performs better in a fire environment, has a significantly longer life expectancy, requires far less maintenance and overall affords substantial savings.

Abstract: In a screened inductance sensor having a drive winding, a sense winding, and a conductive screen for varying the induced voltage in the sense winding by reason of the eddy currents generated in the conductive screen in the presence of the drive field, a physical barrier is interposed between the region of the sensor in the windings are located and the region in which the screen is located. These regions are fully environmentally isolated from each other by the physical barrier. The construction is especially suited to screened inductance level gauges, in particular for fuel tanks, where the conductive screen is part of a float assembly in contact with the fuel, but the electrical windings are kept dry in a separate portion of the gauge.

Abstract: In a control system for a reluctance motor driving a load, the output of a reference waveform generator is applied to a power converter through a current controller. The output of the generator is determined by rotor position, as detected by a sensor. The generator establishes a relative magnitude for motor phase current for every position of the rotor during the period of energization of a motor phase. A further control input may determine the absolute magnitude of the motor phase current, subject to the waveform pattern established by the generator. The reference waveforms may be sinusoidal. A method of determining the configuration of suitable reference waveforms for a given motor involves monitoring selected parameters of motor operation while controlling other such parameter in a test procedure.

Abstract: A screened inductance level transducer has a drive winding for setting up a drive field, and a sense winding in which voltage is induced in the presence of the drive field. A conductive screen, which may be of stainless steel, is mounted on a float for movement in response to liquid level. In the presence of the screen, eddy currents are generated to establish a counter-field opposing the drive field and to thereby shade the sense winding to vary the voltage induced in it. The screen is contained within a tubular barrier which may also be of stainless steel, and the windings are located outside the barrier. In this way, the region within which liquid level is to be measured is isolated from the environment to the exterior of the unit, thus facilitating its use for recording liquid levels in hostile conditions.

Abstract: In a screened inductance sensor for a brushless d.c. motor, a sensor rotor carrying conductive screens is mounted on an extension of the motor shaft. A single solenoidal drive winding on a stator of the sensor establishes a drive field, when energized, which induces a voltage in a sense winding, also carried on the stator. This sense winding is laid around the periphery of a notional cylinder coaxial with the rotor and stator and has series-connected loops of generally rectangular configuration when viewed in development. The screens pass between the drive winding and the sense winding in operation of the sensor to modulate the sense winding output by shading the drive field. The single drive winding is located radially inwardly of one axial end of the sense winding, so that this axial end is aligned with an axially central region of the drive winding midway between its axial ends.

Abstract: In a sensor having a drive winding for establishing a forward field, an electrically conductive screen is displaceable relative to a sense winding. In the presence of the drive field, eddy currents are generated in the screen to establish a counter-field opposing the forward field, so that the sense winding is shaded by the screen to a varying extent during relative displacement of screen and sense winding and the voltage induced in the sense winding is accordingly correspondingly varied. Application of a high frequency input to the drive winding results in a modulated output from the sense winding which may be demodulated to provide a signal indicative of screen position relative to sense winding. The position signal may be further processed to provide a speed signal. The sensor may assume a multiplicity of linear or planar, rotational and axial or solenoidal configurations.

Abstract: In a screened inductance sensor system having a drive winding energizable to set up an alternating magnetic drive field, a sense winding links the drive field and a screening element modulates the spatial distribution of the drive field, when in the vicinity of the sense winding. Variations in voltage induced in the sense winding provide an indication of the relative position of the screening element and the sense winding. The drive winding and the sense winding are accommodated in a displaceable portion of the sensor, and the screening element is fixedly located relative to the movable sensor portion. Modulation of the spatial distribution of the drive field occurs when the displaceable sensor portion is moved into the vicinity of the screening element.

Abstract: In a sensor having a drive winding for establishing a forward field, an electrically conductive screen is displaceable relative to a sense winding. In the presence of the drive field, eddy currents are generated in the screen to establish a counter-field opposing the forward field, so that the sense winding is shaded by the screen to a varying extent during relative displacement of screen and sense winding and the voltage induced in the sense winding is accordingly correspondingly varied. Application of a high frequency input to the drive winding results in a modulated output from the sense winding which may be demodulated to provide a signal indicative of screen position relative to sense winding. The position signal may be further processed to provide a speed signal. The sensor may assume a multiplicity of linear or planar, rotational and axial or solenoidal configurations.

Abstract: In a power supply system, an inductance L is connected between a rail at a voltage V.sub.1 and a rail at earth through a switch S. When the switch is opened, a current i.sub.2 flowing from the inductance L is directed to a third rail through a diode D, voltage on the third rail rising to V.sub.2. The system may function as a dc to dc converter with an output voltage between the V.sub.1 rail and V.sub.2 rail equal to V.sub.2 -V.sub.1. The system may alternatively be used in, for example, a reluctance motor drive, in which case a further inductance with associated switch and diode is included in the circuit in inverse configuration to prevent excessive voltage rise on the third rail.

Abstract: A drive system includes a reluctance motor, driving a load. The motor has stator and rotor poles and magnetizing windings for each stator pole. The airgap is small so that saturation occurs during pole overlap, and the poles are constructed so that there is torque overlap between phases as successive phases are energized during rotor rotation. A sensor provides a rotor position input to a reference waveform generator. The output of the generator is determined by rotor position and is applied to a power converter through a current controller. Accordingly the waveform generator establishes a relative magnitude for motor phase current for every position of the rotor during the period of energization of a motor phase. A further input may be applied to the system to determine the absolute magnitude of the phase current, subject to the waveform pattern established by the generator.

Abstract: In a servo control system for a reluctance motor, the output of a reference waveform generator is applied to a power converter through a current controller. Under standstill conditions, at least two of the motor windings are energised so that both forward and reverse torques are established, the forward torque being in equilibrium with the reverse torque. The controller may be responsive to a bias signal to establish said torques. The control system may form part of a reluctance motor drive system.