Abstract: A proximity switch for signaling the location of a movable member at either of opposite end limits of movement relative to a stationary frame includes a movable member, such as a piston, traveling along a fixed path of movement between a first position and a second position and having an aperture formed within the movable member extending from one end toward another end. A housing encloses a portion of the movable member to form a first fluid chamber between the movable member and a first end of the housing, and to form a second fluid chamber between a second end of the housing and the movable member. Expansion of the first fluid chamber drives the movable member to the first position and expoansion of the second fluid chamber drives the movable member to the second position.

Abstract: A pressure sensor probe has a first port connectable to a relatively low pressure source in a compressor crankcase and a second port connectable to a relatively high pressure source at the output of an oil pump. A shuttle is slidably disposed in a bore and has a first end which closes the first port when the difference in pressure between the two ports indicative of normal operation exceeds a selected value determined by the relative areas of the shuttle exposed to the respective pressures and by a coil spring which biases the shuttle away from the first port. A passage is formed between the shuttle and the bore leading from the second port to a force receiving surface on the high pressure side of the shuttle. The length and cross sectional area of the passage is selected to provide a desired dampening or time delay between the high pressure source and the force receiving surface.

Abstract: A pressure differential bypass sensor switch with thermal lockout that utilizes change in position of a permanent magnet carried by a reciprocable piston responsive to pressure differential in a fluid system to actuate a magnetically actuatable electrical switch. Opposite sides of the reciprocable piston are exposed, respectively, to high pressure and low pressure sides of a filter located in a fluid circulating system. The reciprocable piston is normally positioned at the high pressure side of a passage in which it reciprocates, due to biasing by a spring acting on it from the low pressure side of the passage. As the filter becomes clogged, the pressure differential across it and, therefore, across the reciprocable piston will increase. The bypass sensor is calibrated so that a maximum allowable pressure differential in the fluid system will drive the reciprocable piston to the low pressure side of the passage.

Abstract: A switching device with a normally open electrical condition which engages contacts in response to a rise in fluid pressure for the purpose of activating an associated electric powered device such as a fuel pump in an automobile when pressures are much greater than zero.

Abstract: A switching device operated in response to changes in fluid pressure, including a housing supporting a switch conductor and including a movable terminal support which is insertably attached to the housing, the terminal having a contact surface thereon in sliding engagement with an exposed surface of the conductor to maintain electrical continuity even while there is relative insertive movement between the housing and support member.

Abstract: A pressure operated switch has a bistable or multi-stable latching mechanism disposed between a bellows unit and an electrical switch. The latching mechanism has two relatively axially moveable elements which extend and contract with subsequent operations of the bellows unit to provide the bistable action.

Abstract: There is provided a hydraulic pressure operated electrical switch having a spring biased piston which is movable by the force of the hydraulic pressure of the fluid to be sensed to activate a microswitch. The pressure required to move the piston can be altered by adjusting the force produced by the spring acting on the piston. An operating pressure differential is provided by a diaphragm which operates to move the piston by reason of the hydraulic pressure exerted thereon. The diaphragm has a spring rate and produces a force in conjunction with the spring bias against the piston when the piston is moved as a result of the hydraulic pressure overcoming the spring bias. The spring rate of the diaphragm is affected by the amount of hydraulic pressure exerted thereon so that, as a result of adjusting the operating pressure of the switch, the operating differential pressure is altered.

Abstract: A piston position detecting device including a cylinder tube, a cap cover and a head cover closing both ends of the cylinder tube, a piston slidably provided within the cylinder tube, a piston rod connected to the piston on its axis and passing through the head cover, a ring-shaped permanent magnet provided on one end of the piston and at least one reed switch provided in at least one cover and extending into the interior of the cylinder tube with the reed switch being displaced axially from the center of the piston and provided transversely to the axis of the piston.

Abstract: An electrical pressure switch is used on a hydraulic system to indicate the presence of a minimum operating pressure. The hydraulic fluid acts on a piston to move the piston against a force exerted by a calibration spring. Movement of the piston ultimately closes the contacts of a switch, thereby delivering an electrical signal indicative of minimum operating pressure. A check valve moves in concert with the piston and isolates the internal structure of the pressure switch from escalating hydraulic pressure.

Abstract: A mounting apparatus for a proximity switch for sensing the position of a piston within a fluid operated, expandable chamber cylinder. The mounting device comprises a block shaped member with at least a first depressed, arcuate surface, the degree of curvature of which is adapted to fit the surface of the cylinder. By first attaching the mounting apparatus to the proximity switch and then positioning the proximity switch with respect to the fluid cylinder, tightening down of fastening devices provided for the proximity switch will cause the arcuate surface to firmly engage the surface of the cylinder, thereby providing a secure, vibration resistant mounting of the proximity switch to the cylinder.

Abstract: A pressure sensor adapted for use in pressure switches, pressure detectors, pressure measuring instruments, etc. has a housing. The housing has at one end a force balance valve including a gas chamber sealed at one end by a valve diaphragm and filled with a pressurized gas, and at the other end a pressure receiving section sealed at one end by a pressure receiving diaphragm. The housing further has first and second cylinders with corresponding first and second pistons held in contact with the valve diaphragm and the pressure receiving diaphragm, respectively. Between the first and second pistons is provided a connecting member with an actuating section. The housing further has a working section which is actuated by the actuating section to provide an output or signal externally.

Abstract: A tire pressure detector comprises a hollow cylindrical casing having an internal screw thread for attachment to an inflating valve of a tire. A transverse partition member which divides the casing into two chamber is provided with a projecting pin for pushing the inflating valve to an open position. A cap member is secured to the casing for closing one of the chambers, and a piston member responsive to the pressure is mounted in the chamber. An alarm means is connected to the piston member and has a portion extending out through the cap member. The alarm means may be a graduated rod or an electric light means.

Abstract: A fiberoptic sensing system comprising a light source, a sensor responsive to external stimulus, an optical fiber connected to the light source and the sensor, a detector arranged to receive light from the optical fiber, and output electronics electrically connected to the detector. The sensor includes a reflective surface arranged so as to reflect light from the optical fiber. This reflective surface is movable relative to the optical fiber. The light source comprises a light-emitting diode and a reference diode electrically connected to the source of electrical energy and to the light-emitting diode. A beamsplitter is disposed about the light source, the optical fiber, and the photodetector. The detector includes a transimpedance amplifier and a RMS to DC converter. The output electronics includes a gain control and a offset control. The sensor may be either a temperature sensor or a pressure sensor.

Abstract: The device is applied to the wheel of a motor vehicle and includes a component that is sensitive to the pressure inside the tire and has a conductive, sliding element. When this element reaches the extreme limits of its travel it closes an electrical contact and activates a radio transmitter whose signals, picked up by a receiver located in the passenger compartment, activate a visual and/or acoustic alarm.

Abstract: A switch responsive to fluctuations in the level of a vacuum. A ball is contained in an upright chamber and is normally in contact with an actuating means in the chamber. The actuating means is normally biased to one position but is shifted by the weight of the ball to another position. The chamber is connected to the vacuum source so as to apply a lifting suction force to the ball. If the suction force exerted by the vacuum exceeds a predetermined level, the ball will be lifted from the actuating means thereby shifting the position of the actuating means and generating a signal indicative of the vacuum level. Means are provided to adjust the level of vacuum necessary to lift the ball from the actuating means.

Abstract: A contactless proximity switch and mounting arrangement for determining the position of a movable member within a cylinder which has two end covers secured on the cylinder by means of a plurality of tie rods, includes a switch housing which secures to one of the tie rods. A contact opening formed in the switch housing has disposed therein, a switch having a pair of contacts and a permanent magnet disposed in a fixed manner. One pole of the permanent magnet is connected to a first contact, while the second pole is disposed in a contacting relation to the cylinder. A second contact is electrically coupled to the cylinder at a position a predetermined distance from where the second pole is disposed. As the movable member, which is constructed of a ferromagnetic material, nears the switch housing, the air gap between the second contact and second pole is bridged and the contacts close indicating the proximity of the movable member to the switch element.

Abstract: A low oil pressure sensor (32) is provided for direct mounting to a lubrication pump (4) for direct sensing of differential pump pressure. An internal sensor body portion (40) is exposed to the internal pump environment and has a magnetically permeable piston (48) axially slideable therein. High and low pressure aperture ports (56 and 50) through the internal sensor body sidewalls communicate respective high and low pressure sides of the pump to respective axial ends (58 and 54) of the piston. A radial gap (60) between the piston (48) and the interior sidewall (62) of the internal body portion provides a long narrow axial damping passage for damping high pressure pulses and transients from the high pressure side of the pump, to prevent false triggering. A magnetic coil (66) in the body detects piston movement according to changed flux linkage.

Abstract: A device is provided for the very accurate measurement of fluid pressures, comprising a vertical cylinder (2), a piston (1) adapted for sliding in this cylinder with viscous friction, the pressure to be measured being applied to the upper face (23) of the piston in an upper enclosure (22), means for rotating said piston in said cylinder, a precision electromagnetic dynamometric display balance (B) comprising a piece (3) to which the force to be measured is applied and means for transmitting to the piece of the balance the force applied to the piston by the pressure to be measured, with limitation of the maximum forces, a lower sealed enclosure (22a, 44A-44d), this lower enclosure being able to be evacuated or pressurized to a desired pressure (the atmospheric pressure or that of a fluid), and means for permanently supplying the clearance between the piston (1) and the cylinder (2) with fluid.

Abstract: A pressure differential bypass sensor switch that utilizes the change in piston of a permanent magnet that is carried by a reciprocable position to actuate the switching element of an axial travel switch by the change in magnetic forces that act on the switching element as a result of the change in position of the reciprocable piston and the permanent magnet. Opposite sides of the piston are exposed, respectively, to the high pressure and low pressure sides of a filter in a liquid circulating system, and the piston is normally positioned at the high pressure side of a passage in which it travels by a spring that acts on it from the low pressure side. As the filter becomes clogged the pressure drop across it and, therefore, across the piston will increase, and the piston is calibrated so that an excessive pressure drop will drive it to the low pressure side.

Abstract: A pressure switch having a ball valve or contact mounted in an internal chamber to move in response to predetermined relatively high and relatively low fluid pressures in an inlet that opens into the chamber to make or break an electrical circuit through the switch and that incorporates a one-piece sealing element that is constantly exposed to the fluid pressure and is uniquely formed and cooperative with the ball contact and with the walls of the chamber to prevent leakage of the fluid from the chamber effectively without significantly interfering with free unobstructive movement of the ball contact in use.

Abstract: A differential pressure operated electrical switch construction is provided and has a housing carrying a pair of rigid terminals and an electrical switch for electrically interconnecting the terminals together under the control of an actuator that is responsive to differential pressure acting across the same. The terminals have free ends angled toward each other and the switch comprises a movable contact member and a spring operatively associated therewith for urging the contact member into bridging contact with the free ends of the terminals to thereby place the terminals in electrical contact with each other.

Abstract: A pressure fluid reservoir comprising a cylinder with a reservoir connection, a piston displaceable in the cylinder and non-contact switch means for indicating piston positions. Between the reservoir connection and the piston, the cylinder encloses a pressure fluid chamber, which is intended for storing a pressure fluid such as hydraulic oil, brake pressure fluid or the like. Opposite the pressure fluid chamber, the piston defines a gas chamber. The non-contact switch indicating means comprise Reed contacts, for example, and are disposed outside the cylinder such that they are longitudinally adjustable along the cylinder. Adjustment is effected by a temperature-dependent adjusting means, embodied for instance as an expansion element. Permanent-magnet actuating means, for actuating the Reed contacts in a non-contacting manner are fixed in recesses in one side of the piston.

Abstract: An oil pressure monitoring system for an engine having an oil pressure switch comprising a piston located in a port associated with the lubricating system of the engine. The piston is biased into the port by means of a spring. Located between the piston and the wall of the port so as to undergo compression with movement of the piston into the port is an elastic, electrical conductor ring. The ring is placed in series in a warning circuit and is so constructed that compression of the ring resulting from a drop in oil pressure within the lubricating system will affect conductivity through the ring to initiate a warning signal.

Abstract: A passive programmable resistance device uses a closed loop feedback for controlling resistance to rotational or translational motion of an object. One or more actual parameters, such as force or position, are measured and compared with desired parameters. The differences are used to provide a control signal which controls the resistance to the movement of the object.

Abstract: In a method and apparatus for measuring the pressure of a liquid in a closed storage tank, a measuring piston is guided in a cylinder and is acted upon on one side by a pressure dependent on the pressure to be measured, the piston being in communication with a load measuring device. In order to compensate for the pressure exerted by gas and/or vapor in the interior space of the tank, that side of the piston opposite to said one side is acted upon by this pressure. This is achieved by enclosing the cylinder and the piston in a container filled with a blocking gas, such as nitrogen. The pressure of the blocking gas in the container is controlled by a regulator operation of which is controlled by sensing means for sensing the gas and/or vapor pressure in the interior of the tank.

Abstract: A precision pressure gauge in which a sleeve is installed between the open section of a cylinder and the ram so as not to rotate the ram but only to rotate the sleeve, and the ram is actuated by fluids led into a cylinder chamber of the cylinder so that the force exerted on the ram is transmitted to a precision electronic weight measuring instrument for continuous high precision measurement of the aforementioned fluids.

Abstract: The transducer device disclosed herein is designed for measuring the pressure of a moving fluid stream. The device includes a body member with a lengthwise bore therein and a pressure orifice in communication with the bore. Positioned in the bore is a one-piece piston consisting of a rod segment, a first stem segment extending from one end of the rod, a base segment at the opposite end of the rod, and another stem segment which extends from the base. The base is slideable in the bore of the body and there is an annulus section between the rod segment and the bore. A linear spring means is fitted over the rod, such that it occupies the annulus section. Ahead of the first stem is a sensor unit, which connects into a pressure indicator, for visually indicating pressure values. In operation, the body is mounted on a structure, such as a transfer line, which carries a fluid under pressure.

Abstract: Fluid under pressure is routed through an input port to a bore provided within a housing. A piston is disposed within the housing for movement within the bore. A target member includes a piston portion which frictionally engages, and is received within, the wall of a bore provided in the piston, causing the piston and target to move as a unit. A proximity sensor mounts to the housing in a location to switch to its activated state in response to displacement of the target member to a position corresponding to a predetermined fluid pressure level. Spring packs, exhibiting a predetermined wear characteristic, resiliently bias the piston to resist displacement due to applied fluid pressure.

Abstract: A method and apparatus for measuring a pressure, particularly the pressure of a fluid, employ a pressure-charged measuring piston movable in a cylinder and connected to a load or displacement measuring device. The piston is maintained floating or contact-free within the cylinder by hydrostatic or pneumatic fluid in the form of a release agent supplied between the piston and the cylinder under pressure.

Abstract: For the very accurate measurement of fluid, particularly gas or hydraulic fluid, pressures, the device comprises a vertical cylinder, a piston adapted to slide in this cylinder with viscous friction, the pressure to be measured being applied to the upper face of the piston, means (motor) for rotating said piston in said cylinder, an electromagnetic precision weighing machine with a display comprising a shaft to which is applied the force to be measured, and means for transmitting to said shaft the force applied to the piston by the pressure to be measured, with limitation of the maximum forces.

Abstract: An accumulator fluid indicator useful to measure the linear displacement of a piston without the use of a dynamic seal. A Hall Effect sensor mounted on the outer surface of the accumulator is used to sense the piston location while isolated from the fluid flow. Temperature and pressure sensors may be used to supplement the accuracy of the position indicator by compensating for errors due to changes in temperature or pressure applied to the pressurant.

Abstract: An apparatus containing a cylinder with a piston displaceably guided therein and positionally adjustable by a hydraulic fluid medium. A capacitive measuring transducer is arranged in the cylinder. The measuring transducer comprises a tube attached at the piston and arranged in a longitudinal opening thereof. The tube is electrically conductively connected with the cylinder. Apart from the tube, the measuring transducer further comprises a rod protruding into the tube and insulatingly secured at the cylinder. This rod is connected by means of an electrical bushing or lead with the input of an electronic unit attached externally at the cylinder. The electronic unit comprises an oscillator having a connection electrically coupled with the cylinder and a connection coupled with the non-inverting input of a capacitive feedback differential amplifier. The inverting input of the differential amplifier is electrically connected with the rod which is secured so as to be electrically insulated at the cylinder.

Abstract: In the gas shortage detection device of a piston-type hydropneumatic accumulator, a control rod slidably mounted in the cylinder head on the gas side is displaced under the action of the thrust exerted by the piston when this latter comes closer to the cylinder head than a predetermined distance. A flexible motion-reversal coupling element such as an inextensible cord which works in traction and has a predetermined dead range of travel is placed between the piston and the sliding rod.Correct performance of the detection device can thus be checked by partial draining of the oil compartment, the detection device being triggered into operation when the piston comes close to the bottom end of the cylinder.

Abstract: A gas flow indicator including an open-ended cylinder, a piston constrained within the cylinder to move between the ends thereof, and a reed switch positioned on the outside of the cylinder for responding to the position of a magnet secured to the piston is disclosed. The piston is closed at its end adjacent the output aperture of the cylinder and is open at its end adjacent the input aperture of the cylinder for defining a basin within the piston. A spring is positioned between the piston and the output aperture for forcing the piston away from the output aperture. Gas flowing in through the input aperture forces the piston toward the output aperture. An indication of the state of gas flow through the cylinder is provided in accordance with whether the switch is open or closed.