Abstract: An angular displacement sensor for limited angle applications (e.g., for sensing automotive throttle positions) comprising first (14) and second (16) relatively rotatable components arranged to confront each other axially. The first component (14) provides a plurality of poles (14A, B, C) which are angularly disposed about the rotation axis and extend towards the second component. These poles (14A, B, C) have axes which extend in the same direction as the rotation axis. Some poles have windings (14A, B), while others (14B) provide flux return paths. The second component comprises an inductance affecting component (16) which overlies only some of the wound poles at any given time, the relative rotation varying the poles which are overlaid. The sensor includes an output unit (17) for providing output signal data related to the inductances of the excitation poles and thus related to the rotary configuration of the components.

Abstract: An elongate vessel, preferably cylindrical, is partially filled with a conductive and/or ferromagnetic fluid. At least two coils are wound on the vessel in longitudinally different regions so that tilting the vessel varies the amount of the fluid inside the coils differently. This affects their inductances. The variation in inductances is monitored, directly or indirectly, e.g. by applying an AC signal to the coils and monitoring the voltage drops across them. This provides an electrical output related to the inclination of the sensor's axis. It is unaffected by rotation about the axis. Thus the sensor can be used to monitor the orientation of the axis of a drilling tool, e.g. a mole, which rotates about its axis.

Abstract: An inductive displacement sensor has first and second elements which define a path for movement. The first element has coil portions which interact with an inductance affecting part of the second element so that the inductances of the coil portions vary with movement of the inductance affecting part, only some of the coil portions being affected by the inductance affecting part at any time. The coil portions are arranged in two series connections, each series connection being at least two coil portions electrically connected in series. Coil portions of the two series connections are then arranged alternately. In this way, substantially sinusoidal output signals may be obtained.

Abstract: Displacement along a linear or rotary path causes relative displacement of a pair of elements (101,102) that confront each other across the path. One element (101) provides a series of coil portions (AB,BC), while the other (102) has a portion which increases the inductance of the fraction of the coil portions that it lies adjacent at any instant. The coil portions are homopolar. Typically each coil portion has an axis which intersects the path, and all are wound in the same sense about their axes. They are generally connected in series as a single winding on a core (101). The core has unwound portions (104) for providing a flux return path.

Abstract: Two members 21,22 are relatively displaceable along a linear or circular path. One member 21 provides a plurality of coil portions along the path. Their individual inductances are dependent on the configuration of the second member 22. For example, the first member 21 may be an annular stator with inward radial projections k,l,m . . . on which the coil portions are wound, alternately in different senses so that the flux path tends to loop in and out. The second member 22 may be an annular rotor, one section 23 being ferromagnetic and the other section 24 being non-ferromagnetic and/or having a conductive screening layer. Alternatively the second member may be mercury 42 half-filling an annular conduit 40 which surrounds a static ferromagnetic core 44 (FIG. 9). A particular characteristic is that for any relative position of 21 and 22, half the coil portions of 21 have a different inductance from the other half.

Abstract: An apparatus and method for determining the position and orientation of a remote object in relation to an observation point comprises a transmitter for sending a magnetic field signal and a receiver for receiving and analyzing the magnetic field signal. The transmitter or the receiver is positioned at the observation point and the other is secured on the remote object. The transmitter has three coils positioned on a ferromagnetic core with their axes mutually orthogonal to each other and connected to a polyphase power to produce a magnetic field around the coils. The coils are connected and energized in pairs to produce a magnetic field rotating about the axis of the third coil. The receiver has three coils positioned on a ferromagnetic core with their axes mutually orthogonal to each other and responsive to the magnetic field produced by the tranmsitter. The receiving coils are connected in pairs to detect the phase relationship and magnitude of the signal to indicate the orientation of the remote body.

Abstract: A set square has substantially the form of a 30.degree./60.degree./90.degree. triangle having therein an aperture having sides at 15.degree. and 45.degree. to each external side. The aperture may be in the form of a 30.degree./30.degree./120.degree. triangle disposed with its longest side closest to the hypotenuse of the 30.degree./60.degree./90.degree. triangle and at an angle of 15.degree. thereto, said side diverging from the hypotenuse towards the 30.degree. vertex of the 30.degree./60.degree./90.degree. triangle; preferably a line is indicated perpendicular to one of the external sides other than the hypotenuse, the line being indicated adjacent said side and extending across said aperture, and being indicated on either side thereof. There may be a protractor scale whose origin is at the intersection of the line and the perpendicular side.

Abstract: To provide an indexed drive to a device such as a rotary switch having a detent mechanism, a three step-phase stepping motor is wound with only two of the phases (A, B) in its stator slots (S1-S24). Those slots (*) which would carry the third step-phase winding in a conventional machine are left empty. To index the drive from one detent position (I) to the next position (J), first the step-phase (A) and then the step-phase (B) are energized, to take the detent mechanism past its top dead center position (X). The drive then continues to the next position (J) under the detent force and its own inertia, while the step-phase (B) is kept energized to provide electrical retardation to prevent overshoot.

Abstract: A single phase or multiphase dynamo electric machine including a stator having at least one winding arranged to be energized to provide an alternating flux, and a further member, e.g. a rotor, movable with respect to the stator and having at least one short circuited winding, providing at each position of the movable member alternative paths of low and high reluctance to the passage of alternating magnetic flux, to cause the movable member to adopt a position in which linkage of the short circuited winding(s) with the stator winding(s) is minimized. The machine operates as a rotary solenoid or where the stator windings are in quadrature, as a double acting solenoid. The stator windings may be short circuited to increase the self aligning torque or where three stator windings are provided, by energization of one stator winding and by connecting the non-energized stator windings in opposition, again the self aligning torque can be increased.

Abstract: A single phase or multiphase dynamo electric machine including a stator member having at least one winding arranged to be energized to provide an alternating flux, and a further member, e.g. a rotor, movable with respect to the stator and having at least one short circuited winding providing at each position of the movable member alternative paths of low and high reluctance to the passage of alternating magnetic flux, sensing means for sensing the relative position of the two members, switching means actuated by the sensing means to cause the movable member to lock in position relative to the stator at a null position and to effect successive energization of the stator winding at other than the null position to effect continuous movement of the movable member past the stator.

Abstract: An actuator has a fail-safe mechanism operable by a spring. The spring is normally held inoperable by electrical means so that the fail-safe mechanism is independent of the normal operation of the actuator. The fail-safe mechanism is rendered operative by failure of the electrical supply so that the spring rotates a cam plate which is coupled with the switch plate so as to move the output shaft to a predetermined fail-safe position by the stored energy of the spring force.

Abstract: This invention relates to an electrically operated actuator for quarter-turn valves, such as butterfly or ball valves.The actuator includes a single phase 2-pole dynamo-electric machine comprising a stator having three windings and a rotor having a plurality of short-circuited windings. The rotor is coupled directly with the output shaft and the windings of the stator are energised from a power supply through respective limit switches which are cam controlled by the output shaft.One of the stator windings controls the final movement of the actuator in each direction of travel and the limit switch for this winding is broken to de-energize the winding by an adjustable stop mechanism.