초록 ▼

A method for measuring the level of filling, such as the level of oil in an automotive engine, employs a hot-wire measuring device in which a hot-wire transmitter (5) is charged with a predetermined constant current, and an increase in voltage over the hot-wire transmitter is detected within a prede

A method for measuring the level of filling, such as the level of oil in an automotive engine, employs a hot-wire measuring device in which a hot-wire transmitter (5) is charged with a predetermined constant current, and an increase in voltage over the hot-wire transmitter is detected within a predetermined period of time. Errors due to digitizing and inaccurate calibration are avoided by the simplest possible means. For this purpose, a current source (1), which is controlled by an input voltage, is used as a source of the constant current. Furthermore, in a preparatory stage, after an assembly of the hot-wire measuring device, an input voltage (PWM) is changed until, at an input-voltage value wherein the current source (1) produces the predetermined constant current (IK). The input-voltage value is used in subsequent measuring stages to control the source of current.

대표청구항 ▼

A method of measuring level of filling by means of a hot-wire measuring device having a hot-wire transmitter, comprising charging the hot-wire transmitter with a predetermined constant current, the charging producing an initial value of measurement voltage developed over the hot-wire transmitter; de

A method of measuring level of filling by means of a hot-wire measuring device having a hot-wire transmitter, comprising charging the hot-wire transmitter with a predetermined constant current, the charging producing an initial value of measurement voltage developed over the hot-wire transmitter; detecting an increase in the measurement voltage developed over the hot-wire transmitter from said initial value within a predetermined period of time, the increase in the voltage serving as a measure of the filling level of a fluid; employing a source of constant current controllable by an input voltage, to provide the constant current in said charging; and in a preparatory stage, after assembly of the hot-wire measuring device, adjusting the input voltage to obtain a value of the constant current for making said initial value of measurement voltage equal to a reference value of voltage, and storing the value of the input voltage for use in measurements of filling level to be performed subsequent to said preparatory stage.