A METHOD AND CIRCUIT FOR DETECTING AVERAGE OIL PRESSURE OR OIL FLOW RATE IN A LUBRICATING SYSTEM

In this method for monitoring a system containing a flowing medium, for example a lubricating system for a transmission, for bearings or such like, oil is supplied by means of a pump from a reservoir, sump or such like, if necessary via coolers, filters etc., to the parts to be lubricated. In order to be able to detect that the pressure and flow characteristics and, in the case of a lubricating system, the mean lubricating state are correct, in a simple manner, it is provided that the pressure and/or the flow rate of the medium are measured and the measured values are compared with predetermined minimum values, and an alarm signal or switch-off signal is produced if the number or duration of positive measurements within a specific measurement interval is less than a predetermined minimum number or minimum duration. The measurements are preferably carried out periodically and the measurement intervals follow periodically one after the other. A possible circuit arrangement for carrying out the method is characterised in that the outputs of a pressure and/or flow sensor (6,7) are connected via a switch (8,14,15) which can be operated periodically to an input in each case of a comparator (9,16,17), to whose other input is supplied a pressure or flow nominal value voltage (UPS, UDS), and in that the output of the comparator (9) or the outputs of the comparators (16,17) is/are connected to the input of a counter (12) whose counter state can be interrogated and reset periodically, and in that a comparator circuit (13) is provided for comparing the periodically interrogated counter state with a nominal counter state value (SZ), at the output of which comparator circuit (13) the alarm or switch-off signal (sa) emerges (Figure 2).