US 12,460,980 B2
Upper and lower limit detecting apparatus and method for electric chain block
Yusaku Ido, Nakakoma-gun (JP); and Takuma Isshiki, Nakakoma-gun (JP)
Assigned to KITO CORPORATION, Nakakoma-gun (JP)
Appl. No. 18/265,510
Filed by KITO CORPORATION, Yamanashi (JP)
PCT Filed Nov. 9, 2021, PCT No. PCT/JP2021/041199
§ 371(c)(1), (2) Date Jun. 6, 2023,
PCT Pub. No. WO2022/123984, PCT Pub. Date Jun. 16, 2022.
Claims priority of application No. 2020-206139 (JP), filed on Dec. 11, 2020.
Prior Publication US 2024/0035907 A1, Feb. 1, 2024
Int. Cl. G01L 5/00 (2006.01); G01L 1/26 (2006.01)
CPC G01L 5/0061 (2013.01) [G01L 1/26 (2013.01)] 4 Claims
OG exemplary drawing
 
1. An upper and lower limit detecting apparatus for a load suspending device of an electric chain block including an electric motor, a rotational force transmission mechanism rotated by the electric motor, a rotating device rotated by the rotational force transmission mechanism, and a load chain wound on the rotating device to perform hoisting and lowering, wherein a load engaged with the load suspending device attached to a load-side end of the load chain is hoisted (lifted up) or lowered (lowered down);
the upper and lower limit detecting apparatus comprising an upper limit reaching detection device detecting reaching of the load suspending device to an upper limit, and a friction clutch (overload preventing coupling) provided in the rotational force transmission mechanism;
wherein reaching of the load suspending device to the upper limit during the hoisting is detected by the upper limit reaching detection device, and reaching of the load suspending device to a lower limit during the lowering is detected by judging, with an electric power type overload limiter, that power consumption of the electric motor has exceeded a predetermined value as a result of activation of the friction clutch,
wherein a judgment threshold value of the electric power type overload limiter for the lowering of the load suspending device is set to a value less than a judgment threshold value of the electric power type overload limiter for the hoisting of the load suspending device and greater than power consumption in no-load lowering of the load suspending device.