| 摘要 |
PURPOSE:To eliminate erroneous function due to electromagnetic noise and to eliminate unstable output due to vibration or rocking. CONSTITUTION:A tubular holder 2 bonded with an ultrasonic oscillator 1 has a lower end immersed below oil level L. A sensor 3 is mounted on the oil pan of an automobile and senses the oil level L. When the oscillator 1 is driven with electric pulses, vibration is transmitted down on the holder 2 and reflected vibration is received by the oscillator 1. Liquid level is detected based on the phase difference between the transmitted wave and the received wave. A soft magnetic pipe 4 surrounding the oscillator 1 and the holder 2 shields magnetic noise and prevents fluctuation of liquid level, caused by vibration or rocking, from functioning on the holder. |
