1998-02-23

Transformer Based Sensor Of The High Pressure Fuel Pump Rod Position 980165

The main feature of the described sensor is its contact-less construction. The lack of contacts on the moving rod increases reliability of the sensor.
The sensor comprises the core with the short - circuited two - layer secondary winding. In addition, the sensor is provided with the two multilayer windings, the first being the long primary winding, the second one is the short output winding. The output signal is induced on the output winding. In order to produce the output signal, the alternating voltage with frequency of 20…50 kHz is applied to the primary coil. Depending upon the core position of the short-circuited winding, the current of various values will be induced, which causes various voltages to be induced on the output winding.
The position of the core may vary in range 0...40 mm. The range can be modified in a particular construction. The output characteristics of the sensor are roughly linear. This is achieved by proper choice of exciting voltage frequency and sensor operating mode, that does not involve full magnetization of the core.
The core is the only moving part of the sensor. The body of the sensor is fixed on the fuel pump body. The core is made as a unit with the fuel pump rod. Such construction increases reliability of the sensor.
The sensor is surrounded by steel shield that makes the sensor mechanically strong and protects it from external magnetic fields as well as reduces radiation of the sensor itself. The construction of the sensor is simple.
The paper describes the calculations of the sensor construction parameters, equal electrical circuit and electronical part of the sensor. It also describes experimental characteistics of an actual sensor device.

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