An electric potentiometer including a wiper lever having brush wipers, which upon a rotational movement about a pivot shaft sweep over electrically conductive layers applied to a carrier plate. A resistor layer is joined at one end to a connection layer and at the other to a grounded connection layer. The layer is joined at one end to a pickup connection layer and at the other, via a supplementary layer resistor, to the connection layer. A sliding layer of electrically non-conductive paste material is disposed between the carrier plate and the resistor layer, the latter of which is formed from a paste material provided with carbon particles. The sliding layer is wider than the width of the wiper and the resistor layer.
A potentiometer, which avoids problems caused when abraded material collects on the surface of the potentiometer track as a result of friction between the wiper contact and the potentiometer track, causing an undesirable increase in the contact resistance. Potentiometer track and wiper contact wear is also speeded up by this abrasion, which shortens the service life of the potentiometer. The novel potentiometer has a magnet, on a movable extension arm, that removes the abraded material from the surface of the potentiometer track in a contactless manner, thus preventing increased deposition of abraded material on the potentiometer track that would otherwise occur with increased time in operation. The novel potentiometer is especially suitable for air flow rate meters of mixture-compressing, externally ignited or air-compressing, self-igniting engines.
An electrically conductive polymer film composition includes a polymeric resin, an electrically conductive substance intimately mixed in sufficient quantity with the polymeric resin to render the polymeric resin electrically conductive, and particles, such as fibers or spheres of appropriate size, admixed with the polymer composition in sufficient quantity so that in the cured polymer film the particles protrude from the surface of the film and render the surface uneven on a micro scale. The cured polymer film composition of the invention is incorporated in potentiometers and similar electric and electronic devices as a thick film where a contact wiper rides substantially continuously in contact with the protruding fibers.
A fuel level indicator system that utilizes a resistor card having an arc-shaped resistive path with a first set of spaced apart conductor lines and an arc-shaped resistive ink material overlying the first set of conductor lines. The first conductor lines are formed at an angle with respect to a radial line drawn from the center of the resistive path arc. The resistor card also has an arc-shaped continuously solid conductor base and a second set of spaced apart conductor lines extending from the base at an angle with respect to a radial line drawn from the center of the arc-shaped conductor base. The system includes a wiper assembly having a pair of spaced apart arms. Each arm has a plurality of parallel fingers extending from one end. One of the fingers on a first arm engages a conductor line on the resistive path and a second finger on the first arm engages an adjacent conductor line along the resistive path. A first finger on the second arm engages a conductive line on the conductive path; and a second finger engages an adjacent conductor line on the conductive path. The wiper assembly is constructed and arranged to provide rotational movement along the arc-shaped conductive path and arc-shaped resistive path. The system also has a float with an extending lever that is connected to the wiper assembly to produce rotational movement of the wiper assembly as the float moves.
A position sensor (25) includes both a position potentiometer (90) and a turns count potentiometer (92). The position potentiometer (90) includes a pair of wipers (12 and 14) positioned on a rotor (10) which each contact both a resistive track (46) and one of two different commutator tracks (48 and 50) on element (26). The sensed percentage of total voltage output, which is a function of the position the wiper (12 or 14) contacts the resistive track (46), corresponds to the angular position between 0.degree. and 360.degree. of the shaft on which the position sensor (25) is mounted. The turns count potentiometer (92) comprises a turns count rotor (66) which is incrementally advanced via a cog (18) on rotor (10) using a gear or geneva type mechanism. The turns count rotor (66) includes a wiper (64) which either contacts both a resistive track (150) and commutator track (152) or contacts one of a plurality of switch pads (154). By determining the sensed voltage output from the turns count potentiometer (92) or identifying which switch pad (154) the wiper (64) has contacted, the number and direction of full revolutions of rotor (10) can be determined. The precise angle of the shaft on which the position sensor (25) is mounted is determined by adding the resulting angles obtained from the position potentiometer (90) and turns count potentiometer (92).
A nonmetallic electrical contact or wiper composed of material such as carbon fiber, in which an electrical signal is transmitted along a length of the carbon fibers. The carbon fibers can be fused or conductively bonded together. The carbon fibers can be affixed to a carrier using various bonding and fastening techniques. The carrier can be electrically conductive or not depending on the application and can be affixed to the carbon fibers by bonding, fusing, or mechanical fastening. Alternatively, the electrical contact can be formed entirely from the carbon fiber material, with any carrier being also formed of carbon fiber material.
