Oil pressure sender unit with reinforced diaphragm

摘要

An oil pressure sender unit is disclosed which employs a two-part housing with a reinforced rubber diaphragm disposed between the two housing parts in order to isolate a pressurized oil cavity from a dry circuit cavity which contains the electrical components of the sender unit. In the preferred embodiment the reinforced diaphragm includes a peripheral lip which mates with a corresponding groove located within one part of the housing which is a metal base. The base has an axially extending inlet passage with a damper plug inserted therein which together defines a plurality of volume chambers that receive high pressurized pulsating oil at the inlet side and, because of its design, delivers a smooth flow of high pressurized oil to the underside of the diaphragm. This causes less wear on the electrical contacts that engage a two-sided circuit card which has a resistor circuit on one side and an on/off circuit on the opposing side. The resistor circuit produces an analog signal proportional to the sensed oil pressure, and employs a movable contact that is integral with a piston that rests upon the diaphragm. The on/off circuit includes a metal contact integral with the piston which is operable to engage a conductive material on the surface of a ceramic circuit card in order to complete a circuit and energize an auxiliary device. An alternative grooveless sender base and reinforced diaphragm is provided which is of lower cost than the above design.