SU875215A1

SU875215A1 - Metal presence detector

Info

Publication number: SU875215A1
Application number: SU802886588A
Authority: SU
Inventors: Владимир Кузьмич Бехтер; Иван Трифонович Нападайло; Евгений Митрофанович Антощенко; Анатолий Александрович Сильченко; Валерий Александрович Кольчицкий
Original assignee: Научно-исследовательский и опытно-конструкторский институт автоматизации черной металлургии
Priority date: 1980-02-13
Filing date: 1980-02-13
Publication date: 1981-10-23

Description

(54) ДАТЧИК НАЛИЧИЯ М1ТАЛЛЛ(54) AVAILABILITY SENSOR M1TALL

II

Изобретение относитс к автоматике и изме-, рительной тех1шке и может быть использовано в системах автоматического управлени технологическими процессами дл определени наличи металла в заданной точке пространства или определени взаимного положени металлических тел.The invention relates to automation and measuring technology and can be used in automatic process control systems to determine the presence of a metal at a given point in space or to determine the relative position of metal bodies.

Наиболее близким к предлагаемому вл етс датчик наличи металла, имеющий генератор высокочастотных колебаний, выполненный на транзисторе, чувствительный элемент, представл ющий собой катушку колебательного контура с разомкнутым маг1ттопроводом, змиттерный повторитель, вьпюлненный на транзисторе и служащий дл уменьщенн вли ни последующих частей схемь на работу генератора, схема выпр млени , пороговое устройство Подключение эмиттерного повторител к генератору осуществл етс с помощью обмотки св зи 1.Closest to the present invention is a metal presence sensor, having a high-frequency oscillator, made on a transistor, a sensing element, which is an oscillating circuit coil with an open magnetic circuit, a zmitter repeater, connected to a transistor and serving to reduce the effect of subsequent parts of the circuit straightening circuit, threshold device The emitter follower is connected to the generator by means of the connection winding 1.

При отсутствии металла в зоне действи чувствительного элемента высокочастотные колебани через эмиттерный повторитель и схему выпр млени воздействуют на пороговое устройство и удерживают .его в первом устойчивом состо нии.In the absence of metal in the zone of action of the sensing element, high-frequency oscillations through the emitter follower and the rectifier circuit act on the threshold device and hold it in a first steady state.

При внесении металла в зоне действи чувствительного элемента возрастают потери в колебательном контуре, что приводит к срыву генерации и, как следствие, переключению порогового устройства во второе устойчивое состо ние.When metal is introduced in the zone of action of a sensitive element, losses in the oscillatory circuit increase, which leads to a breakdown of generation and, as a result, switching the threshold device to the second steady state.

Недостатками этого датчика вл ютс низка чувствительность и нетехнологичность настройки The disadvantages of this sensor are low sensitivity and low-tech settings.

10 срабатывани .10 triggers.

Недостаточна чувствительность объ сн етс тем, что подключение змиттерного повторител к высокочастотному генератору осуществл етс через обмотку св зи, что снижает добротность The lack of sensitivity is due to the fact that the connection of the emitter follower to the high-frequency generator is carried out through the communication winding, which reduces the quality factor

Claims

15 of the oscillating circuit by shunting the input impedance of the emitter follower, as well as by the adopted method of adjusting the zone of response in the manufacturing process, in which for each end sensor a metered damping is introduced into the circuit (strip of aluminum foil superimposed on the open part the magnetic core of the coil 3 of the oscillating circuit), which also reduces the quality factor of the circuit. Decreasing the quality factor of the circuit does not allow obtaining the maximum possible sensitivity. The low tuning of the pickup zone is that the position of the aluminum foil is adjusted before the sensor is installed in the sensor housing - (the trigger zone is not guaranteed to remain after placing the sensor element in the sensor housing) and there is no possibility of additional setting of the sensor zone sensor housing. The purpose of the invention is to increase the sensitivity of the sensor. The goal is achieved by the fact that in the case of the presence of a metal containing a high-frequency oscillator on a transistor with a sensitive element made in the form of an inductance with an open magnetic circuit connected to the collector of the transistor, the emitter follower is connected to In addition to the threshold element, a variable resistor included in the emitter circuit of the generator transistor, the emitter of which is connected to the input of the emitter surface, is additionally introduced Oritel. The drawing shows the principal electrical circuit of the proposed sensor for the presence of metal. The sensor has a generator of high-frequency oscillations made on transistor 1, the emitter circuit of which includes an additional variable resistor 2, a sensitive element 3, which is an oscillating circuit coil L) with an open source line, a zmitter repeater made on transistor 4 and connected to the emitter circuit the transistor 1, the rectifying circuit 5 and the threshold element 6. The sensor operates as follows. In the absence of metal in the zone of action of the sensing element 3, high-frequency oscillations through the emitter follower and the circuit 5 of the maximum act on: the threshold element 6 and keep it in the first stable state. When a metal is introduced into the zone of action of the sensing element 3, the losses in the oscillatory circuit increase, which leads to a breakdown of generation and, as a result, the switching of the threshold element 5 to the second stable state. The sensitivity of the sensor is adjusted by varying the gain in the positive feedback circuit of the high-frequency oscillator at transistor 1. To do this, change the value of the additional variable resistor 2, in the transistor 1 of the high-frequency oscillator, into the emitter circuit. The principal difference between the proposed sensor and the known one is that measures are taken to ensure that the quality of the circuit (5x200-250 units) as a component of the sensor is minimally reduced. This is achieved both by rational design of the circuit (connection of the emitter follower not by coil connection, and to the emitter resistor 7), and due to the proposed method for adjusting the sensitivity (changing the gain in the positive feedback circuit using a resistor 2), and not by predosing attenuation, in which the quality of the circuit is 40-50 units, as is the case in the known device. Having an initially high quality, the oscillating circuit has a more acute reaction to the introduction of metal, which is expressed in increasing the sensitivity of the device to 35 mm (instead of 16 mm in known device) when using a magnetic circuit of the same dimensions as in the known device, and tuning the sensitivity with a variable resistor is certainly more technological, thin and accurate compared to the method of measuring tim foil strip position. The invention The presence of metal sensor containing a generator of high-frequency oscillations on a transistor with a sensitive element, made in the form of inductors with an open magnetic circuit connected to the collector of the transistor, an emitter follower, the output of which is connected to a series-connected rectifier and a threshold element, characterized in that, in order to increase the sensitivity, a variable resistor is included in it, included in the emitter circuit of the generator transistor, emit ter which is connected to the input of the emitter follower. Sources of information taken into account in the examination 1. Mechanization and automation of production, № 3, 1973. p. 20-21.

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