SU1401254A1 - Electromagnetic linear displacement transducer - Google Patents

Abstract

The invention relates to a measurement technique. Pel increases the sensitivity and accuracy of an electromagnetic linear displacement transducer by adjusting the degree of shielding influence of the core on its measuring winding and providing temperature correction of its conversion characteristics. The excitation winding 4 and measuring winding 3 of the transducer are placed in the cavity of a split housing consisting of two end-connected and coaxially ferromagnetic and electric erschivators and conductive parts of the conductive part # S7J. The armature of the transducer also consists of ferromagnetic 9 and electrically conducting 10 rods connected by ends. Between the windings 3 and 4 there is a split electrically conducting ring 6, in the section of which an in-case MOS transistor 8 is located, the drain and source of which are electrically connected to the walls of the section in the ring. Using a secondary converter unit connected to the terminals of windings 3 and 4 of the converter and the gate of the MOS transistor and: containing a microcomputer, ADC and a switch, the converter is operated in two modes - calibration, when using the switch and the MOS transistor connect the walls the rings and the winding 3 are shielded from the winding 4, as a result of which the converter becomes insensitive to the position of its core, a correction correction is formed, as well as in the measurement mode, when the shielding ring 6 is EMF is measured and measured on winding 3, depending on the position of the converter core, 2 sludge. with (L to ate 4

Description

The invention relates to a measuring technique and can be used to control the positioning of moving objects.

The aim of the invention is to increase the sensitivity and accuracy of the electromagnetic converter by adjusting the degree of shielding effect of the core on the winding and taking into account the temperature and temporal instability of its conversion characteristics.

FIG. 2 shows the design of an electromagnetic linear displacement transducer; Fig. 2 is a circuit for connecting to the secondary unit for measuring and converting the output signal of the converter.

The transducer contains a hollow cylindrical case, which is made split in length from two parts 1 and 2. Part 1 is made of ferromagnetic material, and part 2 is made of electrically conductive diamagnetic material.

In the internal cavity of parts 1 and 2 of the housing, coaxially solenoid measuring winding 3 and excitation winding 4 are installed. To protect the windings 3 and 4 from damage, an insulating frame 5 is designed. The windings 3 and 4 have a common connection point, which is connected to a common point of the converter. Between the windings 3 and 4 there is a split electrically conducting ring 6 with a cut 7, in which the MOS transistor 8 is placed. Its drain and source are electrically connected to the walls of the ring 6 in the zone of its cut. The gate of transistor 8 is designed to provide a control signal to it. In the cavity of the windings 3 and 4 on the axis of the converter is installed with the ability to move measles, made in the form of connected by the ends of a ferromagnetic rod P and an electrically conductive diamagnetic rod 10. The free end of the ferromagnetic rod 9 is intended for communication with the control object. The free end of the electrically conductive rod 10 and the electrically conductive part 2 of the body are bonded to each other, for example, using an electrically conductive disk forming the bottom of the body. To the free output of the excitation winding 4 a ballast resistor 11 is connected to one end, the other output of which is intended dp

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connect an AC power source (not shown). When performing measurements, a secondary measuring unit 12 is connected to the opposite leads of the excitation winding 4 and the measuring winding 3, as well as to the gate of transistor 8, which includes a micro-computer 13 with information input 14 and two control outputs 15 and 16. To information input 14 connected to the output of an analog-to-digital converter (A1SCH) 17, to the input of which is connected a two-input switch 18, implemented as a pair of controllable electronic switches 19 and 20 connected by outputs, controlled inputs of which are connected to The terminals 15 and 16 of the microcomputer 13 are connected. The input key 19 is connected to the start of the excitation winding 4, and the key input 20 is connected to the terminal end of the measuring winding 3. The control input of the key I9 is connected to the gate of the MOS transistor 8. I

Electromagnetic converter

linear motion works in two clocks. The first step is the calibration, and the second is the measuring one. The converter operation control (switching from the calibration mode to the measurement mode) is performed automatically by the microcomputer 13. In the calibration mode, a high level signal is output at the output 16 of the microcomputer 13, and a low level signal is output at the output 15. This causes the electronic key 19 to be closed and the drain-source of the MOS transistor 8 to be shunted. The key 20 is open and therefore only the excitation winding 4 of the converter is connected to the information input 14 of the micro-computer 13 via the ADC 17. In this case, the walls of the electrically conductive ring 6 in the section section 7 are closed by a MOS transistor 8 and it therefore represents a short-circuited coil in the calibration mode, shielding the excitation winding 4 from the electrically conductive part 2 of the housing and the electrically conductive rod 10 cor. The position of the core does not affect the total inductive resistance of the winding 4. This resistance, however, depends on the temperature instability of the magnetic permeability of the materials of the housing and the core. It is acceptable to assume that these pairs

The meters equally affect the winding 4 of the j6y AeHHH and the measuring winding 3. Therefore, the EMF value on the winding 4 of the excitation with the closed electrically conductive ring 6 is converted by the ADC 17 to the digital equivalent at the input 14 of the micro-computer 13, unambiguously characterizes the temperature change in the conversion characteristic of the electromagnetic displacement transducer at the time of measurement, corresponding to the initial (reference) conditions. By the magnitude of this EMF, the micro-computer calculates the actual parameters of the conversion characteristic and fills them,

In the measuring cycle, at the control output 15 of the microcomputer 13, a high level signal is generated, and at output 16, a low level signal. In this case, the key 19 and the MOS transistor 8 are switched to the open state, and the key 18 is closed. As a result, the measuring winding 3 of the converter is connected to the input of A1SCh 17, and the excitation winding 4 is turned off, the Split ring 6 with open MOS transistor 8 walls in the section of the section ceases to have a shielding effect on the operation of the converter, As a result, the signal of the measuring winding 4 starts depend on the axial position of the rods 9 and 10 and part 2 of the body, i.e., on the displacement of the control object.

Indeed, when the test object moves in the x direction, the position of the ferromagnetic rod 9, the electrically conductive rod 10 and the electrically conductive part 2 of the housing relative to the measuring winding 3 changes. This leads to a change in the degree of shielding of the measuring winding 3 and the equivalent magnetic conductivity in the magnetic flux path generated by the winding 4 excitation and crossing the coils of the measuring winding 3, As a result, there is a change in the value of the emf induced in

measuring winding 3, approximately proportional to the magnitude of the displacement. The exact value of the controlled displacement is calculated from the calibration characteristic of the converter stored in the microcomputer memory 13 and corrected based on the results of the calibration cycle of the converter.

Due to the more pronounced effect of the movement of the core and the associated conductive part of the housing on the EMF of the measuring winding, the sensitivity of the converter increases, and as a result of continuous monitoring of temperature and temporal changes in its conversion characteristics, its accuracy increases.

Claims (1)

Invention Formula Electromagnetic linear displacement transducer containing a cylindrical cylindrical body, placed in it a solenoid measuring wash and measles, executed in the form. interconnected ends of ferromagnetic and electrically conductive rods, the free end of one of which is intended to communicate with the test object, characterized in that, in order to increase the sensitivity and accuracy of the converter, it is provided with an excitation winding placed coaxially with the measuring winding installed between the split , an electrically conductive ring and a MOS transistor located in its section, the drain and source of which are connected to the opposite walls of the ring in the section of the section, the hollow body is a connector two parts in length, one of which is made of ferromagnetic material and covers the field winding, and the second is made of electrically conductive material and is attached to the free end of the electrically conductive rod. FIG. 2