RU2658131C1 - Phase linear displacement sensor - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to measurement equipment and is intended to convert a linear displacement into a proportional phase shift between an output voltage and a reference voltage of the generator. Gist: the phase sensor contains a fixed ruler on which a multiphase flat multi-pole winding is connected to a multiphase electrical voltage generator. Winding consists of nested sections in the number of phases, wound on a ruler in the forward and reverse direction with a shift of half a period. Measuring element in the form of an open magnetic core with a single-phase winding is located above the ruler with the possibility of displacement.

EFFECT: improving measurement accuracy and manufacture processibility.

1 cl, 8 dwg

Description

The invention relates to measuring technique and can be used in feedback channels of closed position automatic control systems for reproducing spatial coordinates, for example, in numerically controlled machines, large-sized industrial robots and manipulators.

Known phase sensors for measuring linear displacements (ed. Certificate of the USSR No. 392539, No. 830118) using information lines with windings placed on them. For example, in linear inductosines, one or two windings shifted by a quarter period and having the shape of a meander are printed on the insulating base of the fixed part. Two or one printed windings are respectively located on the measuring moving part.

The disadvantage of such sensors is the use of the shape of the turns with an information ruler in the form of a meander, in which the implementation of a multiphase winding to create a traveling field is difficult due to the inevitable intersections of the conductors.

Known phase sensor with a running field according to US Pat. RF №2272244, in which a traveling field is formed by two- or three-phase windings laid in the grooves of a linear magnetic circuit. On the fixed part are the sine and cosine windings located at the pronounced poles. The number of turns at each pole must be strictly defined and changeable according to a sinusoidal law. At the same poles there is a stationary measuring winding with the same number of turns at each pole. The output signal is generated using a magnetic shunt that can move along the ruler. The disadvantage of this sensor is the technological complexity in the manufacture of the magnetic circuit and windings.

The technical nature of the closest to the claimed device is a linear selsyn by bus. testimonial. USSR No. 304562, adopted as a prototype. On the fixed part there is a three-phase winding, laid in the grooves of the magnetic circuit, which is the body of rotation. The numbers of turns of the windings laid in the grooves of each phase along the magnetic circuit correspond to a sinusoidal law. On the moving part is a magnetic circuit with a single-phase winding, covering the fixed part.

The disadvantage is the technological complexity of the implementation of the magnetic circuit and windings, especially with a large length of movement. To ensure a sinusoidal law of variation of induction along the magnetic circuit, it is necessary to ensure the exact number of turns along the grooves, which varies according to the sinusoidal law. Since the number of turns can be only integer, there is a methodological error in the reproduction of a sinusoidal law. The same error has the above devices - analogues.

The aim of this invention is to improve the accuracy and adaptability of linear displacement sensors.

This goal is achieved by the fact that the sensor contains a fixed ruler, on which a multiphase winding is placed, connected to a multiphase voltage generator, and a movable part in the form of an open magnetic circuit with a single-phase winding, located above the ruler, in which, according to the invention, the multiphase winding is made in in the form of flat sections nested into each other according to the number of phases, each of which is formed by winding on a ruler a conventional wire in the forward and reverse directions with the same pitch, with this winding in the opposite direction is offset half a period so that the sections of the conductors that form the active contours of the poles of each individual phase retain a diamond shape.

In FIG. 1 shows a prototype device; in FIG. 2 - a flat ruler with a single-phase winding; in FIG. 3 - a flat ruler with a three-phase winding, sections of which are embedded in each other in the same plane; in Fig. 4 - windings of several sensors connected in series to a common star; in FIG. 5 - the relative position of the movable and fixed parts of the phase sensor; in FIG. 6 - placement of the information line on the supporting frame of a woodworking machine with a length of 2200 mm; in FIG. 7 - a fragment of a winding on a ruler (without a protective coating); in FIG. 8 - the location of the stationary and moving parts of the sensor on the said machine.

The design of the prototype contains a fixed magnetic circuit 1, in the grooves of which a three-phase winding 2 is laid, and a movable magnetic circuit 3 with a winding 4. The principle of operation of known AC devices having multiphase windings is the same. For example, in the prototype (Fig. 1), the alternating voltage applied to the winding 4 of the movable part induces an EMF into the phase windings 2, by the amplitudes of which the position of the movable part within one pole division of the phase windings can be uniquely determined. The magnetic field induction lines are closed through a fixed magnetic circuit 1. It is known that all electric machines are reversible: the supply voltage can be applied to the stationary phase windings, and information can be removed from the winding of the moving part. In modern automation, selsyn, rotating transformers, inductosyn and related devices are most often used in the phase sensor mode: a symmetrical multiphase voltage with the appropriate number of phases is applied to a stationary multiphase winding and a rotating or running magnetic field is formed. The winding 4 of the movable part, often single-phase, measures the EMF, the module value of which remains unchanged, and the phase value uniquely displays the coordinate of the movable part within one pole division. This principle is preferable, since the phase is the most convenient and natural parameter for further digital processing.

In the proposed device, the fixed windings do not have their own magnetic circuit, they are wound on a flat ruler 5 of insulating material. In FIG. 2 shows a winding 6 of one phase. It is wound first in the forward, then in the opposite direction with the same step L in straight sections, so the turns form a triangular shape with the peaks 7. At the end of the line 5, the winding starts in the opposite direction so that the vertices 8 of its triangles are opposite the vertices 7 of the forward direction, that is, for this, the turns of the forward and reverse directions are shifted by half a period, forming diamond-shaped contours 9. In this case, the directions of the current densities of the adjacent circuits turn out to be opposite, as shown by round arrows on ur. 2. The magnetic poles of adjacent contours will also be opposite.

In FIG. 3 shows a three-phase winding, sections 10 of which are embedded in each other in the same plane. Sections are connected in a triangle or star. An important quality of this configuration of the windings is the technological simplicity of ensuring the geometric equality of phase configurations, and, therefore, the identity of electrical parameters. This improves the accuracy of the entire device.

A further increase in accuracy can be achieved by simply increasing the number of phases. Obviously, the maximum number of phases will be limited by the minimum possible diameter of the winding wire. In addition, with this method of laying the windings, there is no crossing of electrical connections, as is the case with "meander" laying, which increases the manufacturability and operational reliability of the device. The presence of gaps between the conductors eliminates the interturn circuit. The ruler is quite easy to mount on a curved surface.

To ensure linear motion transformations in several coordinates, for example, in a multi-coordinate automatic system, the windings of several sensors can be connected in parallel or in series in accordance with the rules for connecting multiphase circuits. For example, in FIG. 4 shows a diagram of two sensors 11 and 12 connected to a common star.

Measuring element i.e. the movable part of the proposed device is a transformer with an open magnetic circuit 13 U- or W-shaped, located above the ruler 5. The distance between the poles is equal to half (or close to it) of the step of the winding L (Fig. 2). The relative position of the movable and fixed parts of the sensor is shown in FIG. 5. A textolite or plastic information ruler 5 with a multiphase winding 14 is glued directly to the supporting structure of an object 15, for example, an automatic system, through an insulating gasket 16. A protective coating 17 of PCB or plastic is glued over the ruler 5. The magnetic circuit 13 contains a single-phase winding 18. The magnetic field generated by the multiphase winding 14 is closed through the structure of the object 15 and the magnetic circuit 13 located on the moving part of the system. When a multiphase winding is fed by a symmetric system of multiphase voltages, a traveling magnetic field is created, which induces a constant amplitude and a phase in the single-phase winding 18 of the moving part of the EMF and a phase whose value is proportional to the linear movement of the moving part relatively stationary. The conversion of the phase of the signal in the winding 18 into a control signal, for example a constant voltage, is carried out by well-known widely used circuitry.

The device was tested on a multi-axis woodworking machine with numerical control. Three-phase voltage in the form of a meander shifted by an angle of 120 degrees is generated by a microprocessor control system of the machine. After amplification, it is fed through a matching transformer to several sensors according to the number of system coordinates included, for example, according to the circuit in FIG. 4. The information parameter is the phase of the first harmonic in the transformer winding, which is distinguished by filtration. With the "meander" form of voltage in the multiphase winding 14, the signal in the single-phase winding 18 will have a step-sinusoidal shape. As is known from the theory of three-phase systems, the third harmonic and multiples of it are absent for a symmetric system of voltages, so filtering of the first harmonic is simplified. The proposed design makes it technologically easy to increase the number of phases, and the creation of a multiphase meander system for a microprocessor system is not difficult. This increases the sinusoidality of the output signal in the single-phase coil 18 of the sensor by increasing the number of its stages, therefore, the accuracy of phase reproduction is increased and filtering is simplified.

In FIG. 6 shows the installation of a ruler on a machine frame with a length of 2200 mm, FIG. 7 fragment of the winding information line (protective coating not installed). The pitch of the winding 14 is 36 mm; therefore, such a sensor is functionally identical to a multi-pole electric machine or a multi-turn sensor with a rotating field. These devices are widely used in modern automation. On Fig shows the relative position of the movable and stationary parts of the sensor.

The magnetic core 13 of the transformer is located at a distance of 1-5 mm from the surface of the line 5. Changing the distance during operation affects only the amplitude of the signal in the winding 18 of the transformer and practically does not affect its phase. The angular and lateral displacements in the plane of ruler 5 also have little effect. Reliable mechanical protection and rigidity of fastening the sensor parts on the structural elements of the system ensures stability of parameters and high operational reliability of the entire system with sensors of this type.

The present invention compares favorably with the prototype device by achieving the following positive qualities:

- high manufacturability of the device, especially with a large length of the information line;

- increasing the accuracy of reproducing the desired configuration of the magnetic field is achieved by simply adding the number of phases of the multiphase winding;

- high operational reliability of the device due to the absence of intersecting electrical connections and the presence of insulating gaps both between turns and phases;

- manufacturability of mounting on the design of automatic devices (machines, robots, manipulators);

- the ability to mount on curved surfaces.

Claims (1)

Phase linear displacement sensor containing an information ruler with a multiphase winding located on it, a movable measuring element in the form of a transformer, an open magnetic circuit of which is located above the ruler, characterized in that the different phases of the multiphase winding are located in the same plane, and the turns of each phase have a triangular shape and wound on a ruler in the forward and reverse directions with the same period so that the active contours of the poles of each of the phases are diamond-shaped.

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