Abstract: To monitor adequate oil lubrication of an internal combustion engine, air bubbles in the oil flow are detected by means of a sensor arranged in an oil line of a pressure circulation lubrication system and connected to an electronic evaluation system. These air bubbles are an early indicator of inadequate lubrication of the internal combustion engine.

Abstract: A method and an apparatus are proposed for determining and/or monitoring the quantity and quality of a fluid in which a lowering of the boiling temperature is symptomatic of a deterioration in quality. For this, the filling level and the condition of the fluid—in particular a hygroscopic fluid—are determined successively one after the other by a single sensor of a measuring instrument.

Abstract: A sensor for measuring the filling level of a fluid in a vessel, in particular fuel tank is disclosed. The sensor has an electrode group which extends vertically over the fillable vessel height, and dips into the fluid and which forms electrical capacitors whose capacitances change in a measurable fashion when there are changes in the filling level. The capacitances are determined by a connected evaluation circuit and are represented as a signal which describes the filling level. There is at least one measuring electrode which extends over the entire fillable vessel height. A plurality of reference elements are arranged at different reference heights within the fillable vessel height. Optionally, a plurality of measuring electrodes are arranged in such a way that each measuring electrode has a significant change in width at a reference height assigned to it, and wherein the entire fillable vessel height is passed over by the measuring electrodes.

Abstract: A limit-level sensor (3) has a resistance element (4) which has an electric resistance which suddenly varies a transition temperature which lies above the maximum liquid temperature. The resistance element (4) is first of all heated by electric current. Thereupon, the electric resistance of the resistance element (4) is measured. When the resistance element (4) is covered with liquid (2), the heat generated by the electric current is led away so that the temperature of the resistance element (4) is less than its transition temperature. If the resistance element (4) is not covered by liquid (2), this heat is scarcely led away, so that the temperature of the resistance element (4) remains above the transition temperature.

Abstract: A limit-level sensor for measuring level of a liquid has a resistance element which has an electric resistance which suddenly varies a transition temperature which lies above the maximum liquid temperature. The resistance element is first heated by electric current. Thereupon, the electric resistance of the resistance element is measured. When the resistance element is covered with liquid, the heat generated by the electric current is led away so that the temperature of the resistance element is less than its transition temperature. If the resistance element is not covered by liquid, this heat is scarcely led away, so that the temperature of the resistance element remains above the transition temperature.

Abstract: A clutch for a motor vehicle has a sensor device (7) for detecting the limit of wear of friction linings (6), with an electric switch (11) having an electric conductor (13). The electric conductor (13) is severed by a rotatably mounted switching part (14) when the limit of wear is reached. Before the limit of wear has been reached, the switching part (14) is biased by a blocking part (15) into a position remote from the electric conductor (13). It is possible thereby to determine the limit of wear with particular exactitude.

Abstract: In the case of a method for checking the width of the measuring air gap of a magnetic speed sensor, square-wave output signals are generated from the measurement signals of the sensor by means of at least one prescribable threshold value. The pulse duty factor of the output signals is held within a prescribed range in the case of an acceptable gap width. In the case of amplitudes of the measurement signal outside prescribed limits, the pulse duty factor deviates in a reliably measurable fashion from the prescribed range. A circuit has the means for carrying out this method.

Abstract: A device for triggering a control and/or warning process in a motor vehicle has sensors for determining the existing value of the crosswind actually acting on the vehicle. A crosswind warning device for motor vehicles which permits of a reliable warning for the driver even under varying conditions of the wind, has a first device for the determination and evaluation of the limiting value of crosswind in the motor vehicle for determining a crosswind speed limiting value which is dependent on the actual travel conditions of the vehicle. The values detected by a second device for the determination of the existing crosswind value are fed to the first device and compared with the detected crosswind speed limiting values. A driver-information device is actuated as a function of the comparison.

Abstract: A passive magnetic position sensor, has a substrate with a resistance network arranged on it, and a contact structure which is associated with the resistance network and which can be deflected under the action of a magnet device. An electric connection which is dependent on the position of the magnet device is produced between resistance network and contact structure. In order to provide a position sensor which has a high resolution, operates with a little wear, and is constructively simple to produce, the contact structure is developed as contact-spring structure, and the junction points of the resistance network are connected to contact surfaces also applied on the substrate. The contact-spring structure is arranged at a constant distance from the contact surfaces, the latter entering into contact with the contact-spring structure under the action of the magnet device.

Abstract: A pressure sensor has a movable diaphragm stretched directly between the annular pressing surfaces of two housing parts, and an electrical measuring device. In an area that is located radially outward as viewed from the pressing surfaces, the diaphragm has a sealing ring that abuts both housing parts. As a result, transverse vibrations of the diaphragm are reliably supported.

Abstract: A tank display system for a tank filled with fuel, the tank being divided into a main tank and a supplementary tank, has a level limit switch which responds when the main tank is almost empty. If the switch gives off a signal, then a valve is opened, allowing fuel to flow from the supplementary tank into a flood cup of the main tank. Furthermore, this signal activates a unit for detection of fuel consumption, which unit calculates the remaining volume of fuel in the supplementary tank, which volume decreases as a result of the consumption of fuel. As starting volume for the calculation, the completely filled supplementary tank is used. The precise remaining volume of fuel is displayed.

Abstract: The invention is a device for representing changes in barometric pressure comprising an electronic barometric pressure sensor 2 and a digital differentiating circuit in which a differential quotient .DELTA.P/.DELTA.t is found which is connected to a display of the speed of the change in barometric pressure with mathematical sign and numerical figure. The electrical supply for said barometric pressure sensor 2 is obtained in cyclical intervals. The cyclically determined measured barometric pressure values are checked for plausibility, only the plausible measured barometric pressure values being used to find the differential quotient .DELTA.P/.DELTA.t.

Abstract: A device for indicating the level of the axle of a vehicle having a reference mark indicator which follows the level of the vehicle axle is arranged fixedly connected on the axle of the vehicle and changes its position as a result of the change in level. An electric signal which corresponds to the level of the axle is obtained from a resistance network which is firmly attached to the body of the vehicle. In a level indicator which operates with little wear, is economical to manufacture, and nevertheless is of high accuracy, the resistance network has, associated with it, a contact structure which, under the action of a magnet device which is movable by the change in position of the reference mark indicator, can be deflected in the manner that an electrical connection which is dependent on the level of the axle is produced.

Abstract: A device for measuring pressure changes, and preferably for testing the tightness of a fuel tank, wherein a high-pass filter, the time constant of which is greater than the time constant of the pressure changes to be measured and less than the time constant of the pressure changes of the surrounding air, is arranged behind an absolute-pressure sensor pressure in the fuel tank.

Abstract: A passive magnetic position sensor is constructed of an electrically non-conductive, non-magnetic substrate on which a resistance layer and a soft-magnetic, electrically conductive bending-beam structure are arranged. The resistance layer and bending-beam structure are arranged at a constant distance apart partially overlapping each other. The distance apart is selected so that, under the action of a magnet device conducted along the overlapping region of the bending-beam structure and resistance layer, contact is produced between resistance layer and soft-magnetic bending-beam structure. In order to provide a position sensor which permits a precise tapping of voltage, the electrically conductively developed resistance layer has along its longitudinal direction a meander-like structure adjoined by taps which have contact surfaces on the regions opposite the soft-magnetic bending-beam structure.

Abstract: A method for displaying the outside temperature within a motor vehicle in which measured values of the outside temperature are displayed with a greater time delay in the case of increasing temperature on an outside-temperature sensor than in the case of a decreasing temperature. In order to suppress erroneous display of the outside temperature, the time delay is varied as a function of the temperature of the engine.

Abstract: A process and a system for operating a level sensor, particularly for measuring amounts of liquid in motor vehicles, employs a plurality of heatable thermistors wherein a number of the thermistors are covered by liquid depending on the level of the liquid, and are cooled below a breakpoint temperature of the thermistors. The total resistance of the thermistors, which may be connected with further resistors, changes discontinuously as a function of the liquid level. At least one thermistor is located above the maximum possible level. The temperature of the thermistors is increased to such an extent by a feeding of electrical heating power that all thermistors which are above the existing level exceed their breakpoint temperatures, whereupon the total resistance is measured.

Abstract: A position sensor has an electrically non-conductive substrate with a resistance layer and a conductor track serving as a potentiometer tap arranged parallel thereto, and a second, electrically conductive substrate. At least one substrate is of resilient construction, and at least one of the substrates has a soft-magnetic layer. A magnet is mounted for guidance in the direction of the conductor track, and is located at a constant distance away from the conductive track. The two substrates are spaced apart at a distance allowing contact to be produced under magnetic action. The resistance layer and the conductor track each have structural parts which engage alternately into each other along a path of movement of the magnet.

Abstract: In a switch device, suitable for use as active sensor in an automotive vehicle, wherein current through a load can be switched as a function of a physical variable acting on the switch device, two terminals of the switch device can be connected together via a semiconductor switch. They also form the input of a current supply circuit. A sensor produces an electric signal which represents the physical variable and which can be fed to a threshold circuit. The semiconductor switch is controllable in pulsating manner as a function of the output signal of the threshold circuit.

Abstract: In an evaluation circuit for a capacitive sensor, the capacitive sensor and a capacitor form a capacitive voltage divider, the end terminals of which can be fed with opposite-phase alternating voltages of the same frequency. The junction point between the capacitor and the capacitive sensor is connected, together with a tap of a voltage source of high internal resistance, to the input of an impedeance transformer. The output of the impedance transformer is connected to a synchronous demodulator to which at least one phase of the alternating voltage is fed.