Electronic pressure cycle indicator

Abstract

A fluid pressure sensor is employed as a safety device for sensing lubricant pressure levels. A timer is activated to turn on a pump at regular intervals to provide lubrication at such intervals. Pump operation supplies lubricant to a dispensing network which, in turn, causes closure of a pressure switch for activating an oscillator. A comparator circuit compares the accumulated count of oscillator pulses against a predetermined threshold level to trigger an electronic switch which activates an alarm. The pressure switch closure sets a bistable circuit which, in turn, activates said oscillator circuit for incrementing a programmable binary counter circuit. The long-time interval before actuating logical gating circuitry, which interval is adjustable by programming of the binary and/or the R.C. elements in the oscillator circuit and which typically may be of the order of hours, or even days, continues until the voltage output of the logical gating circuitry reaches a predetermined threshold level causing the bistable circuit to reset and turn off the oscillator and causing the activation of the electronic switch. The alarm activated by the electronic switch may be a lamp which is energized to indicate that an unusually prolonged period of time has occurred since the last pump operation. Operation of the timing circuit is not reinitiated until the pressure switch again undergoes a switch closure operation which automatically sets the bistable circuit and turns the lamp off. The delay of the timing circuit is not significantly affected by transients.