公开(公告)号：US20210010848A1

公开(公告)日：2021-01-14

申请号：US16921141

申请日：2020-07-06

Applicant: DENSO CORPORATION

Inventor： Kyoko KUROKAWA ,  Takuya KOIZUMI ,  Akihiro KONNO ,  Hironori IWAMIYA

IPC: G01F23/296 ,  G01B17/00

Abstract: A first arithmetic circuit computes a propagation velocity of an ultrasonic wave based on a first time difference between an output timing, at which an ultrasonic element outputs an ultrasonic wave, and a reference timing, at which a comparator circuit outputs a detection signal on reflection off a distal end of a reference pipe, and a length of the reference pipe. A period circuit sets a propagation path detection period to detect a liquid level timing, at which the comparator circuit outputs the detection signal on reflection off the liquid level, based on a longest and shortest propagation path lengths and the propagation velocity. A second arithmetic circuit computes the length of the propagation path based on a second time difference, which is between the liquid level timing and the output timing during the propagation path detection period, and the propagation velocity.