Showing papers on "Inductive sensor published in 1991"

Inductive proximity sensor and position transducer with a passive scale

Abstract: An inductive proximity sensor, comprising a single length of sensor wire (16,52) supplied at high frequency with an electronic supply (ic1,ic2) circuit for this sensor wire (16,52), and means (R1,R2,ic3) of detecting the greatest electrical losses and diminution of the sensor wire's inductance, as a result of the proximity of metal (20) for the detection of said metal (20); as well as a measurement transducer - linear of rotary - consisting of a scale (43,56,S21) and a cursor (WM1,WM2,72), where the cursor is made up of at least one sensor wire (16,52) and the scale (43,56,S21) is completely passive and made up of transversal short circuits (54) at a constant step, for intercepting a part of the magnetic flux (18) produced; the amount of flux intercepted being cyclically variable versus the relative position assumed during relative movements.

Vehicle detector with series resonant oscillator drive

Abstract: An inductive sensor is driven by a series resonant oscillator circuit to produce an oscillator signal having a frequency which is a function of inductance of the inductive sensor. An inductive load, which includes the sensor, is connected in series with a capacitive impedance. Power to the series resonant circuit formed by the inductive load and the capacitive impedance is controlled as a function of current in the series circuit as sensed by a current sensor. A detection system provides a detector output based upon the frequency of the oscillator signal.

Device for detecting a vessel put in the heating zone of a cooking or heating apparatus

Abstract: The pot detection system operates with an inductive sensor (22) which is arranged close to the heated region of the cooking apparatus (11). The sensor signals are evaluated as a function of the signal rate of change in order to compensate for the poor coil quality of the high-temperature-resistant coils. The evaluation takes place digitally with frequency counting, and a bridging device (50) is provided in order to be able to use the apparatus even without pot detection. … …

Inductive proximity sensor - has oscillator in bridge circuit in branch of current source and continuously restores bridge balance

Abstract: The inductive proximity sensor has an oscillator module (Z3) containing a coil (L1) which is damped by the presence of an object (6). The module forms a branch (3) of the DC supplied (UB) bridge circuit (1 to 4) such that a resultant voltage change (RV) is evaluated (S) for analogue digital load control via the voltage (VA). A branch (1) of the bridge (1 to 4) contains an impedance (Z1) exactly matched to the oscillator's static impedance (Z3) and of identical thermal construction. An AC source (8) controlled by the evaluation unit(s) continuously restores the bridge (1 to 4) balance with the resultant minimisation of source voltage and thermal errors. USE/ADVANTAGE - Also for analogue path measurement. Has improved accuracy and long-term stability as consequence of thermal compensation and insensitivity to spurious oscillatory influences. Is universally applicable to both analogue and digital systems.

Inductive proximity switch with variable oscillator supplying coil - uses tuned circuits in sensor and detector to avoid actuation from other metallic objects

Abstract: The inductive proximity switch comprises a v.c.o. (10), with two inputs (10.1. 10.2) and two outputs (10.3, 10.4), a filter (11) with a series resonant circuit of a coil (12) and a capacitor (13), an amplitude detector (20) a phase shaper (22), a phase comparator (23), a regulator (24) and comparators (25, 26). The induction coil (12) forms part of the resonant circuit (12/13) which is connected to an amplitude detector (20). The operating sensor (19) includes a resonant circuit (16) of the same frequency. USE/ADVANTAGE - Switches in machinery. Avoids mal-operation as it only works with resonant circuit sensor.

Arrangement for distinguishing between opposite movement directions - has inductive sensor of periodic magnetic asymmetries with pole shoes at varying separations

Abstract: An arrangement for distinguishing between the directions of motion of a part (22) with periodic magnetically acting asymmetries (24) has an inductive sensor (20) opposite the asymmetries and not moving with the part. The sensor has different magnetic coupling to the asymmetries in the region of pole shoe areas which are offset in the direction of motion. The pole shoe regions are at different distances from the asymmetries. USE/ADVANTAGE - Esp. for determining the direction of rotation of a toothed wheel.

Inductive sensor for measuring length

Abstract: An inductive length-measuring stylus has a base body in which a contact rod is guided to move horizontally. The base body further contains a primary coil, to which an AC voltage is to be applied, and a secondary coil that can be connected to evaluation electronics. Both coils are magnetically connected to one another via ferromagnetic return devices. All the parts, situated in the field of the primary winding, of the ferromagnetic return device are fixed, in order to improve the linearity of the length-measuring stylus for a given stroke, or to increase the stroke for a given linearity.

Proximity sensing for robots

Abstract: External sensing is used to tell the robot what is happening in its working environment. These systems are based primarily on principles related to human touch, vision and hearing, with some other techniques, such as magnetics, also used. The paper describes some of the different types of proximity sensors and ranging methods used in robot systems, including; inductive sensors; capacitive sensors; photoelectric sensors; acoustic sensors; Pentax Autofocus sensor; ultrasonic time-of-flight ranging; and laser based time-of-flight ranging.

Inductive angular transducer for determining shaft rotation

Abstract: Mounted in a rotationally secure fashion on a steering column in order to determine the rotational movement thereof is a pick-off element (12) which is constructed in the shape of a pot and has radially offset projections (17, 18). The contours of these projections (17, 18) extend in opposite senses. A fine signal is generated with the aid of an inductive sensor (13) by the pick-off element (12) by varying the inductance of the measuring coils (34, 35). This fine signal is repeated several times when the steering column is rotated. In order to assign this fine signal unambiguously, a second sensor (44) and a short circuiting ring (40) moving axially relative to the steering column are used to generate a coarse signal. The exact angular position of the steering column can be determined by computationally relating the coarse and the fine signals. The angle sensor (13) is of very compact design and supplies relatively accurate measuring signals.

Inductive sensor, esp. for vehicle revolution rate meter - has injection moulding housing contg. coil body with coil and pole pin passing through housing which has plate supporting seal

Abstract: The inductive sensor has a housing (11) at least partially made of plastics with a coil body (12) having at least one coil (13) in which a pole pin (14) is arranged. The pole pin protrudes through the injection moulded plastics housing which has a plate-like protrusion (25) in the region of the pole pin. The protrusion is in contact with the pole pin and a sealing device (24) is placed in contact with the protrusion inside the housing. An annular recess (26) is formed between the wall of the housing and the protrusion (25). USE/ADVANTAGE - Esp. for installation in various types of car. Is constructed so as to be almost absolutely sealed and produces accurate measurement signal with large amplitude.

Vehicle detector measurement frame segmentation

Abstract: A vehicle detector includes one or more inductive sensors connected to an oscillator circuit. A timing circuit defines a plurality of sequential measurement frame segments. The oscillator circuit is coupled to an inductive sensor during each of the measurement frame segments. The time duration of each of the plurality of measurement frame segments is measured. After the completion of each frame segment for a particular inductive sensor, a total measurement frame time duration for that sensor is calculated based upon durations of a predetermined number of measurement frame segments for that sensor. The total measurement frame time duration and a reference time duration are compared and a difference is determined. If the difference between the total measurement frame time duration and the reference time duration exceeds a threshold value, an output signal indicative of the presence of a vehicle in the vicinity of the inductive sensor is generated.

Appts. converting mechanical actuation into analogue electrical signal - uses profiled cam coupled to spindle sensed by inductive proximity sensor to produce proportional signal

Abstract: A mechanical adjustment action applied to such as valves is in the form of a rotary actuation about an axis (4). Coupled to the spindle of the device is a cam (2) with a surface profile that has different radial lengths for each angular position. As the spindle is rotated, the distance (S1) from the cam surface to an inductive proximity sensor (1) varies. The cam is manufactured from a magnetic material. The proximity sensor output is an analogue signal that is proportional to the displacement and therefore to the angle of movement. USE/ADVANTAGE - Continuous, contactless and thus without wear- detection of amt. of opening of blocking organ, e.g. setting flaps, valve armature.

Vehicle tyre air pressure measurement arrangement - contains measurement piston in non-magnetic measurement tube with e.g. inductive sensor

Abstract: The method measures the air press. in vehicle tyres and detects critical temp. using a non-magnetic or non-metallic measurement tube (1) with a press. measurement piston (4) and two closure stops (2,3) of weakly magnetic material arranged radially on the wheel rim or inside the tyre. The position of the piston w.r.t. the two stops or w.r.t. an inductive transducer is determined for each rotation of the wheel. USE/ADVANTAGE - For tubed and tubeless tyres. Accurate tyre press. measurement.

Safety circuit for proximity sensor - has duplicated processing arrangement to identify fault in sensor unit

Abstract: As non-contact proximity switch is used in detecting when a movable part is near to a fixed part, eg. door near to frame. In order to eliminate faults in sensing, a pair of test signal operators (7,8) providing the same outputs is used to provide a summed input (5) to the sensor (S) to the sensor (S). The output of inductive sensor is monitored (11) and is supplied to computer stages (12,13) that checks the signals against the original signal generator outputs. A logic circuit (14,15) interprets the results to identify any fault condition. USE/ADVANTAGE - Distinguishes between sensor fault and system condition. Protecting machine operator or dangerous area.

Bore outer surface shape determining appts. - has contactless inductive sensor element with coil generating electromagnetic field

Abstract: An arrangement for determining the shape and quality of the surface of a cylindrical metal workpiece such as a bore, bolt or pin contains an inductive, contactless sensor element (6) which is moved along the measurement surface. The workpiece (11) and sensor element act like a fitting with play with the sensor element as the inner or outer element and guided concentrically w.r.t. the workpiece surface. The element contains a coil (9) which generates an electromagnetic field distributed about its surface which interacts with workpiece surface and influences the coil parameters. ADVANTAGE - Can detect threads and thread defects in a single measurement process.

Measurement transducer for physical parameters - has two sensors e.g. capacitive, inductive or resistor sensors, and changeover switch selecting on sensor at time for connection to evaluation circuit

Abstract: The measurement transducer has two sensors (1, 2) whose signals are proportional to a measurement parameter in opposite senses. A single evaluation circuit with a changeover switch (3) is used for both sensors. The switch alternately connects the sensors to the evaluation circuit according to the signal duration. Capacitive sensors with a measurement range of 10 power -12 to 10 power -16 farads are used. Alternatively, inductive sensors with a measurement range of 10 power -6 to 10 power -3 henrys or resistors with a range of 10 - power -3 to 10 - power -6 ohms are used. USE/ADVANTAGE - For converting physical measurement parameters into electrical parameters for evaluation. Measurement errors caused by sensor manufacturing tolerances and temp. and operating voltage variations are eliminated.

Reference mark signal generator for internal combustion engine - consists of induction coil wound on centre of yoke constituting proximity sensor for tip of cam

Abstract: A magnetic-cored inductive sensor (8) has a U-shaped yoke (9) which straddles the path of a cam (5) on the camshaft (2) as the latter rotates in one direction in two bearings (3, 4). The passage of the tip (7) of the cam induces a signal in a winding 910) at the centre of the yoke (9). Even on a four-stroke engine this induced signal corresp. to the proximity of a particular cam gives an unambigous position indication w.r.t. the ignition cycle. USE - For co-ordination and synchronisation of engine control esp. in electronic fuel injection and ignition equipment.

Self adjusting support for workpiece - has pivot mounted support with self locking servo drive and with proximity monitoring to move support surface under workpiece

Abstract: The arrangement has the workpiece clamped into the milling position so that the underside of the area to be milled is supported by a thrust surface (5) on the end of a pivot lever (4). The lever is driven into contact with the workpiece by a servo drive (19, 8) which locks into position when a proximity sensor has indicated that the thrust surface has touched the workpiece. The proximity sensor can be an airjet in the support surface, or it can be a magnetic/inductive sensor. A servo drive has a sprindle drive (8) and a shpaed thrust bearing (22) under the lever. The servo drive is spring loaded to eliminate gear train play. USE/ADVANTAGE - Milling surface faces of connecting rod (1) mounting ends. Ensures accurate surface treatment.

Inductive sensor arrangement e.g. for workpiece parts - has current supply alternately energising coils via variable resistor

Abstract: A voltage comparator, to set a desired position, compares the voltages produced by the respective magnetic coils of the sensor head and the external object with a reference voltage and from the result of the comparison gives a dependent output signal. The current supply unit alternately and repeatedly feeds a current through only one of the two magnetic coils (L1, L2) which, on one side, are connected together and are connected respectively in a series with a common resistor (R2). A measurement voltage (A) drop at the common resistor is supplied to the voltage comparator (4), a reference input(+) of which receives a constant reference voltage (B) for the respective voltage of comparison. The comparator output signal (C or Va) is changed over always to a positive or a negative level, if the measurement voltage has reached the reference voltage. The current change over between the coils results in response to the change over of the output signal level of the voltage comparator. ADVANTAGE - Lateral and height positioning of sensor head and external object to each other. Simple construction and sensor system does not require auxiliary sensors.

Extraction (suction) control device for a sewing machine equipped with a chain (waste thread chainstitch) extractor

Abstract: The control device according to the invention includes: a. a photoelectric cell 6 situated square with the needle plate 1, and preferably built into the latter, upstream of the sewing head 2 and capable of detecting the presence of the sewing-work 7; b. a sensor for counting the revolutions of the balance wheel of the sewing machine, preferably an inductive proximity sensor; c. an electronic circuit, connected to the extractor 4, the photoelectric cell 6 and the counting sensor, programmed so as to control the operation of the extractor 4 on the one hand during a first programmed number of revolutions of the balance wheel recorded by the sensor after the start of detection, by the cell 6, of the work 7 and on the other hand during a second programmed number of revolutions of the balance wheel recorded by the sensor after the end of the detection, by the cell 6, of the work 7.