RU2322758C1 - Inductive sensor of approach - Google Patents

Abstract

FIELD: impulse engineering, in particular, devices for detecting approach of metallic controlling element, possible use for building machines with digital program control and automatic technological lines.

SUBSTANCE: in accordance to the invention, the core of inductance coil of LC-generator is formed by a set of U-shaped ferrite elements. Cross-sections of elements face one side and envelop the winding of inductance coil. Kernels may have varying length. Forming of various configurations of sensitive zone of sensor is ensured when typical ferrite elements are used.

EFFECT: simplification of design, reduced costs and increased distance of actuation.

2 cl, 2 dwg

Description

The invention relates to the field of pulse technology, in particular to devices for non-contact determination of the position of metal controls, and can find application in the design and implementation of control devices for CNC machines, automatic lines.

A device [1] is known, which is an inductive sensor that is triggered when approaching its active zone of a conductive object, such as a metal plate. The known device [1] consists of a metal case, in one end of which there is a sensing element - an inductor, which has one or more windings located in a cup-shaped ferrite core, the open side of which is the sensitive surface of the device. Inside the housing there is an electronic circuit containing components of an LC-generator of a sinusoidal voltage, an amplitude detector, a threshold device, for example, a Schmidt trigger, an output transistor switch. The second end of the housing of the known device [1] is used to attach either a connector or a cable for connecting the device to a power source and a consumer of a useful signal. In this device, the ferrite core used is made in the form of a bowl with an inner core, while the height of the inner core is almost equal to the height of the side wall. The sensitivity zone of the known device [1] is close to the region of space limited by a cone-shaped figure, the base of which is determined by the target of a cup-shaped ferrite core, and the height is determined by both the geometric dimensions of the core and the parameters of the electronic circuit. The disadvantage of the device [1] is the small relative operating distance, determined at about 30 ... 35% of the diameter of the housing. This is mainly due to the shape of the field of the sensing element.

A device [2] is known, the ferrite core of which also has the form of a cup, but with a significantly lower side wall height in comparison with the central core. This shape of the core leads to a change in the shape of the field of the sensitive element due to an increase in its length over the region of the side wall of the core, and also leads to a flattening of the front sensitivity zone, which ultimately leads to an increase in the response distance of the device with the same sensitivity of the electronic circuit. This device [2] is the closest in technical essence to the proposed device.

Known devices [1] and [2] are well-implemented at short response distances determined by values of a maximum of tens of millimeters, however, if necessary, to obtain a sensor with a response distance of hundreds of millimeters, well-known technical solutions cannot be used. The complexity of manufacturing a ferrite core of known geometry of the required dimensions significantly increases, and its price increases sharply, especially with a small production program for the production of such devices.

To provide the possibility of manufacturing inductive proximity sensors over long operating distances, simplifying the design of such sensors and reducing their cost allows the proposed device due to the fact that the ferrite core is made in the form of separate U-shaped elements, the cores of which are directed in one direction and cover the winding of the inductor, when this length of core cores may be different.

The proposed device is shown in figure 1 and figure 2, while only areas of sensitive elements are shown. The device comprises (see Fig. 1) a frame 1 of an inductor, U-shaped ferrite cores 2, a winding 3 of an inductor. The frame may be made of a dielectric material, for example, plastic, textolite, etc., by known methods from known materials. U-shaped cores 2 are placed in the frame, for example, by means of a system of groove elements (cast during the manufacture of the frame with embedded elements, etc.) in such a way that the barrel is directed in one direction and cover the winding 3 of the inductor, forming the active surface of the proximity sensor . The winding 3 of the inductor is included in the oscillatory circuit of the LC generator of the device. The placement order of the U-shaped cores 2 can be either regular or non-regular, which allows you to form the desired shape of the sensitive space of the proximity sensor. The shape of the frame 1 may be such that the jumpers of the U-shaped cores 2 will be located as if in one flat surface (see figure 1), or such that they will be located as if in one conical surface (see figure 2) . Such options for the location of the U-shaped cores 2 allow, with their geometrical dimensions unchanged, to form (within certain limits) the desired shape of the sensitive space of the proximity sensor. In addition, when using U-shaped cores 2 with uneven core cores of the alignment, the range of possible variations increases. The winding 3 of the inductor and its ferrite core in the form of a set of U-shaped cores 2 form a sensitive element of the device.

The proposed device operates as follows. When a supply voltage is applied to an electronic circuit (not shown conditionally) in an LC generator, an electromagnetic oscillation process occurs, as a result of which from the side of the active surface, i.e. from the alignment of the U-shaped cores 2, an electromagnetic field is formed, the configuration of which is mainly determined by the geometry of the location of the U-shaped cores and their configuration. In the initial state, in the absence of a metal in the sensitive area of the device, the output transistor is closed. When a metal sensitive element is introduced into the electromagnetic field, changes in the parameters of the electromagnetic oscillations of the LC generator occur, which (changes) are detected and fed to the threshold device. The threshold device is triggered by a given change in the oscillation parameters of the LC generator, which, in turn, leads to the opening of the output transistor switch. Removing metal from the sensitive area of the device brings the electronic circuit to its original state.

The proposed implementation of the ferrite core of the inductor of the device in the form of a set of U-shaped cores significantly expands the ability to meet various technical requirements for inductive proximity sensors regarding the configuration of the sensitive space when using almost the same components forming the core of the inductor. Obtaining cores of different lengths of one U-shaped core can be achieved by using known methods of machining ferrite materials. This device design allows you to create proximity sensors with unique properties based on typical ferrite elements mastered by the industry.

Information sources

1. Internet document www / balluff.ru.

2. TURCK catalog - TURCK Sensors Catalog, 1994, p. B5.

Claims (2)

1. An inductive proximity sensor, comprising a housing, a sensing element in the form of an inductor with a ferrite core and an electronic circuit, characterized in that the ferrite core is made in the form of separate U-shaped elements, the cores of which are directed in one direction and cover the winding of the inductor. 2. The device according to claim 1, characterized in that the length of the cores of the alignment of the U-shaped core can be different.

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