Broken yarn detecting circuit for yarn feeder

Abstract

The invention discloses a broken yarn detecting circuit for a yarn feeder, wherein the yarn feeder comprises a front broken yarn detector and a rear broken yarn detector. The rear broken yarn detectorcomprises a rear broken yarn detecting circuit and a non-contact inductive switch which is connected in series in the rear broken yarn detecting circuit and is used for sensing the change of the working condition of the yarn. The broken yarn detecting circuit is characterized in that the rear broken yarn detecting circuit comprises a first rectifier bridge, a sampling circuit, an isolating circuit and a signal driving circuit, wherein, the sampling circuit is for collecting a broken yarn signal and is connected with the non-contact inductive switch in series, the isolating circuit is used forisolating an interference signal and the signal driving circuit is used for feeding back the broken yarn signal to the yarn feeder host. Compared with the prior art, the non-contact inductive switchis installed on the broken yarn detector in the invention, and the defect of the poor contact of a traditional touch switch after a long-time use is avoided. In addition, the isolating circuit is increased, thereby implementing the secondary isolation to the interference signal and ensuring the working reliability of the broken yarn detector.

Description

technical field [0001] The invention relates to a detection circuit, in particular to a detection circuit for yarn breakage of a yarn feeder applied to a knitting machine. Background technique [0002] The yarn feeding device (also known as the yarn feeding device) of the knitting machine is generally equipped with a yarn breakage detection device. Once the yarn breakage is detected, the main engine can be stopped in time to prevent holes and broken needles in the woven fabric due to yarn breakage. Or defects such as yarn skipping. [0003] Such as figure 1 , figure 2 As shown, it is a traditional yarn feeding device and its adopted yarn breakage detection method. Metal probe rods (generally stainless steel wires) and metal sheets (generally copper sheets) are arranged in the yarn feeder. The metal probe rods usually include There is a front detection rod 3 and a rear detection rod 7, and the contact part 31 of the front detection rod 3 and the contact part 71 of the rea...

AI Technical Summary

Problems solved by technology

This direct contact detection method has a disadvantage: due to the light weight of the metal probe rod itself, the swing range of the contact part of the probe rod is generally not large when the yarn is broken, and only a slight vibration occurs between the contact part of the metal probe rod and the metal sheet. contact, which leads to a large and unstable contact point resistance. After a period of use, under the action of current, the contact part of the metal probe rod and the metal sheet is prone to chemical and physical changes such as oxidation and carbonization, making this part The contact resistance of the contact resistance increases rapidly (even infinitely large), and finally when the yarn breakage occurs, the detection circuit cannot normally output the yarn breakage fault signal due to poor contact.

However, the detection device in the above-mentioned patent usually includes the cooperation of a transmitter, a receiver and a controller, the detection circuit involves many components, and the corresponding control circuit is relatively complicated, which increases the cost of design, manufacture and maintenance; and , no isolation circuit is designed in the above patent. In the case of no yarn breakage, once there is an external interference signal input, the detection circuit will send a signal to the host, which will cause false shutdown and affect normal work.

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