Capacitance type oil level measuring transducer

Abstract

The invention provides a conversion module for a consumption signal, which comprises an excitation signal generating circuit, a detection circuit, a modulation-demodulation circuit and a pulse signal generating circuit which are integrated in a module by a thick die. In the excitation signal generating circuit, an RC (remote control) bridge-type sinusoidal wave oscillating circuit is connected with a power amplification circuit in series; a switch K 4 and a capacitor C15 are arranged on a control terminal; two alternating current excitation signals generated by the RC bridge-type sinusoidal wave oscillating circuit through the power amplification circuit follow circuits to excite two ends of a consumption sensor through a positive phase voltage and a negative phase voltage respectively, so that a modulation carrier signal is formed during the rotation process of the consumption sensor; and the modulation carrier signal is sent to the pulse signal generating circuit after filtered, detected, amplified and compared by the modulation-demodulation circuit, so that a pulse signal allowing a microprocessor to recognize is generated. The conversion module for the consumption signal has small size, low power consumption and high reliability, overcomes the defects that PCBs (printed circuit boards) in the prior art occupy a large assembly space, and can detect fault information of the consumption sensor in a plane.

Description

technical field [0001] The invention relates to a novel capacitive fuel level measuring sensor mainly used for measuring the fuel oil level height and fuel dielectric constant of aircraft. Background technique [0002] Usually, the sensing part of a general capacitive oil level measurement sensor is a coaxial container. When the oil enters the container, the capacitance between the sensor housing and the sensing electrode changes. This change is converted by the circuit and accurately measured. Linearity and temperature compensation, output 4~20mA or 0-5V standard signal for display instrument. The deficiencies of the capacitive sensor for measuring aircraft fuel oil level in the prior art are: [0003] (1) The sensor does not have a fuel dielectric constant measurement component, so it cannot compensate the error caused by the fuel temperature change to the fuel level measurement. [0004] (2) The positioning method between sensor tubes is generally composed of multiple c...

AI Technical Summary

Problems solved by technology

[0003] (1) The sensor does not have a fuel dielectric constant measurement component, so it cannot compensate the error caused by the fuel temperature change to the fuel level measurement

[0004] (2) The positioning method between the sensor tubes is generally composed of multiple concentric positioning pins that are vertical in space, which has the problems of poor process technology and low positioning accuracy

[0005] (3) The junction box of the sensor is installed in a step-by-step manner with multiple parts. The epoxy resin or elastic rubber in the middle of the junction bolts in the junction box is used to fix the separated parts, so that the signal lead wires of the sensor are in the junction box. The generated parasitic capacitance is difficult to control. Under high and low temperature conditions, the dry capacitance value of the product is seriously out of tolerance

[0006] (4) Fuel pollutants are often deposited on the sheaths installed at both ends of the sensor, causing the capacitance value of the sensor to be seriously out of tolerance

[0007] (5) After the cable in the fuel tank is connected to the signal terminal of the sensor, there is no effective stress buffer device. In the aircraft environment, the swing of the wire will have a greater impact on the lug or ring connected to the terminal , sometimes resulting in loose connections

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