Apparatus for inserting the weft thread by means of a fluid for weaving machines, especially pneumatic weaving machines

摘要

The main nozzle (1) of a pneumatic weaving machine is operated alternately with a transport-air flow of high pressure and high speed and a holding-air flow of low pressure and low speed for the purpose of the careful and economical insertion of the weft thread. The transport flow is switched by means of a switching valve (3). The holding flow leads through a line (8) extending parallel to the switching valve (3) and having a pressure-reducing valve (10) and a non-return valve (9). The pressure-reducing valve (10) reduces the pressure of the air from the compressed-air system (7) to the necessary pressure of the holding flow. The non-return valve (9) closes during the passage of the transport flow through the main nozzle (1) and opens as soon as the switching valve (3) is closed and interrupts the transport flow. The air allowed through by the reducing valve (10) now flows through the non-return valve (9) and supplies the main nozzle (1) with the holding flow. Since the connecting line (11) between the non-return valve (9) and the main nozzle (1) is very short, only a very small quantity of air of high pressure can accumulate in it when the switching valve (3) is opened for the transport flow. This small quantity of air cannot damage the weft thread if there is an overflow to the main nozzle (1). <IMAGE>