Weft insertion method and device in water jet loom

A weft insertion device in a water jet loom that includes a measuring and storing device including a storage device having a rotary yarn guide continuously driven to rotate and a storage drum on which a weft is wound and stored by a rotation of the rotary yarn guide, and a measuring device having a measuring roller which continuously feeds the weft from a yarn feeder toward the rotary yarn guide at a predetermined feed speed corresponding to a weft insertion length, and a weft insertion related device which is involved in a weft insertion and affects a timing at which the weft starts to fly or a state where the weft flies, and is driven according to a set value stored in a set value storage of a weft insertion control device, and wherein the weft insertion device includes the weft insertion control device for controlling drive of the weft insertion related device, in which one weft insertion is performed through a constrained flight process in which the weft flies while being constrained by a feed speed of the measuring roller by being in a state where the weft is drawn directly from the rotary yarn guide without passing through the storage drum, after a free flight process in which the weft flies in a free flight state by being drawn while the weft on the storage drum is released from the storage drum,

• the weft insertion device comprising:
• a weft detection sensor provided so as to face the storage drum, and detecting passages of the weft circulating around the storage drum with the weft insertion, wherein
• the weft insertion control device includes
• a passage timing detector that determines passage timings, wherein the passage timings are based on a detection signal output from the weft detection sensor,
• a reference value storage that stores a reference value of a set position arrival timing at which a leading edge of the weft reaches a set arrival position, in association with the set arrival position, wherein the set arrival position is an arrival position at which the leading edge of the weft reaches in a weft insertion process that includes an end time of the weft insertion, and the set arrival position is one of a plurality of arrival positions where a timing at which the leading edge of the weft reaches the arrival position can be determined from the passage timings in the free flight process,
• an actual value determiner that determines an actual value of the set position arrival timing, based on the passage timings determined by the passage timing detector, where the actual value determiner includes the passage timing detector,
• a comparator that compares the actual value with the reference value, and
• a set value corrector that determines, in a case where a deviation occurs between the actual value and the reference value, a correction amount of the set value based on the deviation so as to change a driving mode of the weft insertion related device so that the deviation decreases.