Abstract: A transducer for measuring a displacement along an axis of movement of a first part relative to a second part, comprises a magnetic source for generating a magnetic field mounted to the first part, and a plurality of magnetic field sensing devices mounted to the second part to be movable relative to the magnetic field generated by the magnetic source. The sensing devices are spaced in the direction of the axis. A circuit arrangement is provided to which the sensing devices are connected to generate an output signal dependent on contributions from the sensing devices of the plurality. The magnetic source has North and South poles oriented in the direction of the axis. The sensing devices are each oriented to respond to an axially-directed component of magnetic field, and comprise at least two axially-spaced sensing devices whose contributions to the output signal are combined in a subtractive fashion.

Abstract: The accelerometer uses magnetic transducer technology. A mass-block, mounted to a base by an elongate member (shaft), moves relative to the base due to accelerations. The elongate-member has at least one magnetised transducer region (circumferential or longitudinal), which emanates a magnetic field as a function of member flexure due to acceleration of the mass-block. A sensor adjacent the transducer detects the field and derives a acceleration-representing signal. Alternatively, a mass-block is mounted to a central hub of a disc which is radially secured and has an intermediate region that flexes in response to acceleration. The intermediate region is magnetised to provide the magnetic transducer element. Otherwise, the mass-block is supported in an aperture of a reference-base by cores of inductors. The core permeability is a function of the compressive tensile forces on the cores due to acceleration of the mass-block.

Abstract: A magnetic torque transducer for a structure such as a disc through which torque is transmitted between a central shaft to which the disc is mounted and an outer periphery such as a gear wheel. The intervening region through which torque is transmitted is magnetized to provide a transducer element having two magnetized, annular regions which cooperate to emanate a magnetic field that is torque-dependent. The two magnetized regions may be longitudinally-magnetized through the disc or circumferentially magnetized with opposite polarities. A sensor assembly of non-contacting sensors is used to detect the emanated field and connected in circuitry to provide a torque-dependent signal. In an alternative a single magnetized annular region is employed. The annular region or regions need not be a complete annulus. The same disc-like structure can also be used as force sensor for measuring bending moments or other forces which result in stress occurring in the disc.

Abstract: A force transducer element (20) comprises a body (22) of magnetisable material having at least one magnetised region (30) at an angle, say 45°, to the force-sensing direction (P—P). Preferably there are a plurality of parallel magnetised regions of alternating opposite polarity of magnetisation to form closed loops (43p, 43n). The element may be a block having opposite force receiving surfaces (24, 24?). The body (122) may contain plural transducer elements (120a, 120b) angled to one another to resolve force directions. The principle is extended to a circular transducer element (243). The invention may be implemented in a flexible magnetic tape. Another embodiment (300) is realised in a planar structure in which a ferromagnetic core (310) is subject to a magnetic field (326) at an angle to the direction (F) of force application generated by laterally offset coils (312, 314). A sensor device (330) is fabricated in the structure.

Abstract: A method of measuring torque in a part, for example a shaft, in which at least one coil, wound about an axis of the part about which axis torque is applied, is A.C. energized to create an alternating polarity magnetic field in the part, which field emanates a component dependent on torque. A magnetic field sensor arrangement is responsive to the emanated component to produce a torque-indicating signal. The at least one coil is energized by a series of energizing pulses of current of alternating polarity which pulses have a relatively small duty cycle. The sensor arrangement produces sensor pulses of alternating polarity corresponding to said energizing pulses, and the sensor pulses are measured in a peak-to-peak fashion to produce an output signal representing torque.

Abstract: Torque in a shaft is detected by means of non-contacting sensors sensing a torque-dependent magnetic field emanated by an integral transducer region of the shaft that is circumferentially or longitudinally magnetized. The shaft is driven by a motor and subject to a longitudinal magnetic field which acts on interference field. In one implementation of the invention coils are energized to provide a counteracting magnetic field to compensate the interference field.

Abstract: Torque is measured in the chain wheel (50) of a pedal cycle by a non-contacting magnetic-based transducer. A magnetising source (70), a D.C. type of source such as a permanent magnet is positioned adjacent the chain wheel (50) to induce an arcuate magnetised zone (72) in the wheel (50) as it rotates. The zone emanates a torque-dependent magnetic-field component that is detectable by a sensor (74) that follows the source (70) in the direction of rotation. By having the magnetising source (70) continually in position the arcuate tranducer zone (72) is refreshed on each rotation of the chain wheel. The nature of the pulsating torque in the chain wheel due to the exertion of the rider and its relationship to the angle of the pedal cranks is discussed with a preference for positioning the source (70) and sensor (74) at positions of minimum and maximum exerted torque respectively. If the induced arcuate magnetisation is interrupted (76) pulses for measuring rotational speed are obtainable.

Abstract: A shaft (40) subject to torque about its axis (A—A) has an axial bore (42). A region (44) of the shaft (40) has a stored magnetisation, the region (44) being permanently magnetised with circumferential magnetisation about the axis (A—A) or an annulus of longitudinal magnetisation which is preferred. The stored magnetisation emanates a torque-dependent field into the bore (42). A magnetic field sensor arrangement (50) is positioned in the bore to produce a torque-dependent signal. The disclosure discusses the relationship between the radial depth (tm) of the permanent magnetisation in region (44) relative to the shaft wall thickness (t). Magnetic sensor placements include axial (52, 54) or offset arrangements of pairs of sensors (52a,b, 54,b). Dependent on the nature of the field to be sensed, sensors (5) may be oriented axially, radially or tagentially with respect to the axis (A—A).

Abstract: Torque in a shaft (61) is detected by means of non-contacting sensors (23, 24) sensing a torque-dependent magnetic field emanated by an integral transducer region (64, 32) of the shaft (61) that is circumferentially or longitudinally magnetized. The shaft (61) is driven by a motor (63) and subject to a longitudinal magnetic field (60) which acts on interference field. In one implementation of the invention coils (L1, L2: L3, L4) are energized to provide a counteracting magnetic field to compensate the interference field (60).

Abstract: A transducer for measuring displacement comprises a transducer assembly in which there is a coil wound about an axis and energisable to generate a magnetic field, and first and second magnetic field sensor devices, that are axially spaced with the coil therebetween, each device being in proximity to the coil to respond to a magnetic field component generated by energisation of the coil. A ferromagnetic member is disposed to interact with the field generated by the coil, the ferromagnetic member and the transducer assembly being mounted for relative displacement in the direction of said axis, such that the balance of the respective field components sensed by the first and second sensor devices is a function of the axial position of the ferromagnetic member relative to the transducer assembly.

Abstract: A magnetic transducer element for use in sensing torque in a contactless transducer system for rotating shaft comprises an annular region of magnetization induced in the shaft by rotating it about its axis with respect to a magnetizing source oriented to create longitudinal magnetization in the annular region. The source may be a U-shaped (horseshoe) magnet with its poles axially spaced and with the gap between the poles substantially greater than the axial width of the poles. The application of torque to the shaft skews the longitudinal magnetization to generate a torque-dependent tangential circumferential field component. This tangential field component is sensed by an external sensor or sensors adjacent but not in contact with the annular transducer region. A pair of transducer regions can be employed as well as guard or keeper regions to enhance and stabilise the transducer region.