Automatic picking regulating method for air jet loom and apparatus for carrying out the same

An automatic picking regulating method for an air jet loom, comprising steps of:

• determining actual running characteristics of a picked weft yarn in one picking cycle of the air jet loom on the basis of a holding pin retraction phase angle when the holding pin is retracted, and an actual yarn arrival phase angle detected by a yarn arrival detector located at a predetermined position on the yarn arrival side of the air jet loom;
• deciding whether the actual yarn arrival phase angle detected by the yarn arrival detector is within a predetermined range defined by a phase angle tolerance;
• determining new reference prejet end phase angles of prejet operation and new reference postjet start phase angles of postjet operation respectively for auxiliary nozzle groups for the subsequent picking cycle on the basis of the actual running characteristics and the respective positions of the auxiliary nozzle groups, when the actual yarn arrival phase angle is outside the predetermined range defined by the phase angle tolerance;
• determining jet start phase angles for the respective prejet operation of the auxiliary nozzle groups advanced by phase angles respectively corresponding to prejet periods from the respective jet end phase angles of the prejet operation, and jet end phase angles for the respective postjet operation of the auxiliary nozzle groups delayed by phase angles respectively corresponding to postjet periods from the respective jet start phase angles of the postjet operation;
• and
• sequentially activating the auxiliary nozzle groups with respect to the picking direction respectively for the total jet periods.

An automatic picking regulating apparatus for an air jet loom, comprising:

• a phase angle detector for detecting the phase angle of the main shaft of the air jet loom in one picking cycle;
• a holding pin retraction timing device which provides a holding pin retraction signal to retract the holding pin of the air jet loom;
• a yarn arrival detector located at a predetermined position on the yarn arrival side of the air jet loom;
• a running characteristics detecting device for determining actual running characteristics of a picked weft yarn on the basis of a phase angle, detected by said phase angle detector, the holding pin retraction phase angle set by said holding pin retraction timing device and an actual yarn arrival phase angle detected by said yarn arrival detector;
• a decision device which decides whether the actual yarn arrival phase angle detected by said running characteristics detecting device is within an allowable range defined by a phase angle tolerance;
• a reference phase angle setting device which sets new prejet end phase angles respectively for the prejet operation of the auxiliary nozzle groups and new postjet start phase angles respectively for the postjet operation of the auxiliary nozzle groups on the basis of the actual running characteristics and the respective positions of the auxiliary nozzle groups, when the actual yarn arrival phase angle is outside the allowable range defined by the phase angle tolerance;
• a phase angle calculating device which determines prejet start phase angles respectively for the auxiliary nozzle groups which are advance by phase angles corresponding to predetermined prejet start periods from the prejet end phase angles for the auxiliary nozzle groups, respectively, and post jet end phase angles delayed by phase angles corresponding to predetermined postjet periods from the postjet start phase angles for the
• auxiliary nozzle groups, respectively;
• and
• a valve control device which activates the auxiliary nozzle groups sequentially for total jet periods, respectively, between the prejet start phase angles respectively for the prejet operation of the auxiliary nozzle groups and the postjet end phase angles respectively for the postjet operation of the auxiliary nozzle groups.