US 12,253,402 B2
Liquid level sensor
Akira Sasaki, Mie Ken (JP)
Assigned to Kuwana Metals, Ltd., Kuwana (JP)
Appl. No. 18/011,860
Filed by Kuwana Metals, Ltd., Kuwana (JP)
PCT Filed Jun. 29, 2021, PCT No. PCT/JP2021/024612
§ 371(c)(1), (2) Date Dec. 21, 2022,
PCT Pub. No. WO2022/004739, PCT Pub. Date Jan. 6, 2022.
Prior Publication US 2023/0258491 A1, Aug. 17, 2023
Int. Cl. G01F 23/60 (2006.01); G01F 23/62 (2006.01); G01F 23/80 (2022.01)
CPC G01F 23/62 (2013.01) [G01F 23/60 (2013.01); G01F 23/804 (2022.01); G01F 23/808 (2022.01)] 24 Claims
OG exemplary drawing
 
1. A liquid level sensor comprising:
a sleeve disposed so as to extend in a vertical direction,
a float configured so as to move along said sleeve according to fluctuation of liquid level,
a resistor string including a plurality of resistors connected in series and having both ends always connected with a direct current power supply,
a plurality of grounding means disposed inside said sleeve respectively corresponding to junction parts between adjacent resistors included in said resistors in said resistor string, and configured such that said junction part is grounded when said float is located within a predetermined distance from the corresponding junction part and said junction part is not grounded when said float is not located within the predetermined distance from the corresponding junction part, and
a liquid level signal output means configured so as to take out an electric signal detected between a positive electrode side end part that is an end part connected with a positive electrode of said direct current power supply among said both end parts of said resistor string and said junction part grounded by said grounding means as a liquid level signal that is a signal corresponding to said liquid level,
characterized by further comprising:
a warning signal output means configured such that a warning signal is output when said float is located within a predetermined distance from a warning position that is a predetermined position within a movable range of said float and the warning signal is not output when said float is not located within the predetermined distance from said warning position, and
a positive electrode grounding means configured such that said positive electrode side end part or said junction part closest to said positive electrode side end part is grounded when said float is located within a predetermined distance from said grounding means corresponding to said junction part closest to said positive electrode side end part among a plurality of said grounding means or when said float is located outside the grounding means, and
a negative electrode grounding means configured such that said junction part closest to a negative electrode side end part, which is an end part on a side opposite to said positive electrode side end part of said resistor string, is grounded when said float is located within a predetermined distance from said grounding means corresponding to said junction part closest to said negative electrode side end part among a plurality of said grounding means or when said float is located outside the grounding means.