Abstract: A gas flow measuring apparatus of the type which measures for example, the amount of air flow to the engine of an automotive vehicle, includes a flow measuring tube, an electric heater wire and two temperature dependent resistance wires which are all positioned in the flow measuring tube such that one of the temperature dependent resistance wires is subjected to the effect of the heat of the electric heater and the other is not subjected to the same effect, whereby the flow rate of gas is measured in accordance with the output signal of a voltage divider including a series-connection of the temperature dependent resistance wires. The electric heater wire and the temperature dependent resistance wire subjected to the effect of the heat from the former are wound closely and alternately on the same support made from an electrical insulating material.

Abstract: A first temperature dependent resistor and a second temperature dependent resistor are disposed within a single gas passage defined by a branch pipe extending into a conduit for a gas whose flow rate is to be measured. An electric heater is located between these temperature dependent resistors and is heated for the purpose of measurement of the flow rate of the gas. A first reference resistor and a second reference resistor constitute a bridge circuit together with the first and second temperature dependent resistors, and the difference between the potentials at the terminals of the bridge circuit is amplified by a first differential amplifier circuit. The difference between the output voltage of the first differential amplifier circuit and a predetermined reference voltage is then amplified by a second differential amplifier circuit.

Abstract: A flow measuring pipe includes therein an electric heater and a temperature dependent resistor positioned downstream of the electric heater. The lines of the electric heater are arranged in a direction to cross the lines of the temperature dependent resistor. If necessary, a flame arrester is further disposed downstream of the temperature dependent resistor.

Abstract: A gas flow measuring tube is provided in a duct through which gas to be measured is flown. In this gas flow measuring tube there are placed an electric heater and first and second temperature dependent resistors which are formed of resistance wires stretched across a plurality of respective insulator frames. A measuring circuit is provided for controlling electric power to be supplied to the electric heater in accordance with the resistance change of the temperature dependent resistors, and thereby measuring the amount of the flow of gas to be measured. The measured values are corrected in accordance with the temperature of the insulator frames.

Abstract: Voltages at the diagonal points of a bridge circuit are amplified in an AC differential manner and half-wave rectified, which bridge circuit is formed of reference resistors and temperature dependent resistors located in front and rear of an electric heater in a duct through which air to be measured flows. The half-wave rectified voltage is sampled and held in synchronism with a control pulse signal from an oscillation circuit so that the sampling and holding operation is performed substantially at the center of the period during which the half-wave rectified voltage is produced. The held voltage and a constant reference voltage are amplified in a DC differential manner and then applied to a power amplifier circuit which controls a supply voltage to the electric heater. The voltage to be applied to the bridge circuit is an intermittent voltage which is produced by a chopper circuit.

Abstract: The amount of axial movement of a plunger is controlled by a hydraulic servomechanism. The pressure in the hydraulic chamber of the servomechanism is controlled by opening and closing an inlet valve and outlet valve provided respectively at the inlet and outlet sides of the hydraulic chamber. When the difference value between the actual position and desired position of the plunger is greater than a first predetermined value, only one or the other of the inlet and outlet valves is energized. When the difference is intermediate the first predetermined value and a second predetermined value which is smaller than the former, the inlet and outlet valves are energized at different duty cycles. When the difference is smaller than the second predetermined value, the valves are both deenergized.

Abstract: A non-linear operational circuit with reference voltage sources and switching means, wherein the output voltage of the operational circuit is compared with the reference voltages to open and close the switching means in accordance with their magnitudes relative to one another and thereby to non-linearly vary the output voltage of the operational circuit in response to changes in the input voltage. The reference voltage sources and the switching means are connected in series between the output terminal and the ground terminal of the operational circuit, whereby at the inflection point at which the ratio of the change in the output voltage of the operational circuit to the change in the input voltage changes, the output voltage is caused to change continuously.

Abstract: In a demodulator circuit for a chopper amplifier including a rectifier and a smoothing filter having a capacitor, an impedance conversion circuit is connected to the output side terminal of the capacitor to ensure holding of the stored charges of the capacitor at each negative half-cycle of the amplitude-modulated AC signal applied to the demodulator circuit. A discharge circuit including a switching element is further provided for the capacitor and the discharge circuit is rendered conductive at each positive half-cycle of the amplitude-modulated AC signal which is also applied to a control terminal of the switching element.

Abstract: An intake air amount detecting system includes a branch pipe disposed in the intake manifold of the engine and having two passages each provided therein with a temperature responsive resistor. One of the two passages is provided with an electric heater and a voltage is applied to the electric heater so that the temperature difference in the two passages measured by the two temperature responsive resistors is maintained at a predetermined value irrespective of the amount of air flow through the intake manifold. An A-D converter is further provided and includes a time constant circuit and a capacitor for producing across the capacitor a reference voltage which has a waveform representing a predetermined relationship between the voltage applied to the electric heater and the amount of intake air flow.

Abstract: A thermally-sensitive resistor is positioned in each of two separate passages provided in the intake pipe of an internal combustion engine, and an electric heater is positioned upstream of one of the thermally-sensitive resistors with respect to the direction of flow of intake air. The thermally-sensitive resistors form, along with two reference resistors, a bridge circuit which converts the difference between the resistances of the thermally-sensitive resistors caused by the electric heater, i.e., the difference between the temperatures in the passages to a voltage difference. A control circuit controls the voltage across the electric heater in such a manner that the said voltage difference is maintained constant and thus the amount by weight of intake air can be directly obtained. The input voltages to the thermally-sensitive resistors are applied in the form of pulses through an oscillator circuit thereby reducing the problem of drift of the bridge circuit.