SU847081A1 - Magnetoelastic differential dynamometer - Google Patents

Description

one

; The invention relates to weighing technology, in particular, devices for measuring the strength difference and can be used, for example, in automated weighing and dosing systems in ferrous metallurgy when weighing and dosing charge materials. .

Known magnetoelastic dynamometers / containing magnetoelastic core, placed in a housing, perceiving the measured load. On the core there is a winding. Air-:: bw, connected to an alternator and a measuring winding connected to the device, according to the indications of which the court is about the magnitude of the applied force 11

H, the number of known dynamometers t is the impossibility of measuring the difference in applied forces.

The closest in technical essence is a magnetoelastic differential dynamometer containing a closed rod magnet duct with three windings, one of which is powered by alternating current of a constant frequency, and the other two are located on different branches of the magnetic circuit.

loads to create in the magnetic core of various local stresses. The windings are included differentially to produce a voltage at the output, the value of which is a function of the difference between the indicated loads 2.

A significant disadvantage of this device is the presence of a disconnected type of magnetic core of the sensitive element and, as a result, the sensitivity of the transducer is low.

The purpose of the invention is to increase

15 sensitivity measurement of the difference of two forces.

This goal is achieved by the fact that the dynamometer is provided with a housing made in the form of a hollow cylinder and a fixing plate with a circular notch into which this cylinder is placed, with its axis perpendicular to the plate. The magnetic core is made in the form of two cores pressed into a hollow cylinder its ends, so that the longitudinal axis of the cores coincides with the plane of application of forces, with the excitation windings and the measuring made each of the 30 two sections placed on both

cores, the excitation winding sections being connected in parallel, and the measuring winding sections in series and counter.

In addition, in order to regulate the initial signal of the measuring winding, the fixing plate is adapted to move along the axis of the cylinder.

Fig. 1 shows the structure of the proposed magnetoelastic differential dynamometer, appearance, with a notch; Fig. 2 is a diagram of the electrical connection of the dynamometer windings and their connection to the generator and the device; fig.Z - static characteristics of the magnetoelastic cores and the entire device,

The magneto-differential differential dynamometer (Fig. 1) includes a housing 1 placed in a fixing plate 2 with a circular cut. Case 1 is made in the form of a hollow cylinder. Magnetoelastic cores 3 and 4 are pressed into the cylinder bore at its ends so that the longitudinal axes (shown by a dash-dotted line) of cores 3 and 4 coincide with the line of action of forces P and Q (directions, action of forces P and Q are shown by arrows). The excitation pulley consists of two sections 5 and 6. Section 5 is placed on the core 3, section 6 is placed on the core 4. The measuring winding consists of sections 7 and 8. Section 7 is placed on the core 3, section 8 is placed on the core 4. Section of the excitation winding 6 and 5 are connected in parallel and connected to the alternator 9 (see figure 2). Section 7 and 8 of the measuring winding are connected in series and counter and connected to the measuring device 10.

B. The present device uses the effect of the distribution of mechanical stresses in a hollow deformable cylinder, one of the cross sections of which is fixed (for example, by means of a plate with a circular cut). When compressing one end of a hollow cylinder, its cross section in a given plane takes an elliptical formula with its major axis in the direction perpendicular to the line of action of the force, and: the cross section of the opposite end. The cylinder cylinder takes an elliptical shape with a major axis in directions, a pair of lines of force. In this case, the cylinder section in the plane of the fixing plate remains unchanged (butterfly-type deformation or flattening of the pipe in the wall). Thus, the deformable body in the form of a hollow cylinder with the magnetic core pressed into its ends in a fixing plate transfers the mechanical force (deformation) of one

core to another with the opposite sign. In the case of two forces, a difference in the measured forces is applied to each magnetoelastic core.

The best effect of using the mechanical properties of the differential dynamometer case is manifested when using elastic steels as the case material in the following geometrical dimensions ratios.

 0.9 - 1.1 dH

L

d 0,6 0,8 and „,

d. where L is the length of the cylindrical body;

d is the outer diameter of the cylinder; dg is the internal diameter of the cylinder (with the thickness of the fixing plate being in the range 1.5-2 to the thickness of the walls of the hollow cylindrical body). Magnetoelastic differential dynamometer works as follows.

In the absence of force P and Q on magnetoelastic cores 3 and 4, the initial forces of press fit PO and QJ act, and the value PO and QQ is the maximum difference of the measured forces P and Q. In this case, in sections 7 and 8 of the measuring winding voltage and and U / jo are induced. Moving the fixing plate 2 along the wasps and cylinder 2 can be met. Conditions and to: UiO Then the output voltage of the dynamometer U will be equal to zero (see fig. H), since the measuring windings are connected consistently and counter. If force P acts on the end of the body with a pressed magnetoelastic core 3, and force Q acts on the end of the body with the pressed core 4 (even if for certainty the condition is met) / then the voltage U induced in section 7 will increase by the value of d 1 )., the voltage Ujj induced in section 8 is reduced by the value of q UQ. Therefore, the voltage at the output of the device will be equal to Di, where di can be found from the ratio

li (1)

Since the voltages induced in the sections of the winding are connected with the applied P and Q forces

AU-, k (P-Q) (Q-P); (, U Q)

(2) then when fulfilling the condition

k.- and sensitivity of the magnetoelastic cores 3 and 4, the relation (P-Q) -k (Q-P) 2k ((P-Q)) will be valid,

.. W

where 2k is the sensitivity of the dynamometer.

Claims (2)

Claim 1. A magnetoelastic differential dynamometer containing a closed magnetic circuit with field windings and a measuring coil, and an alternating current generator, so that, in order to increase the sensitivity of measuring the difference of two forces, it is equipped with a circular cutout which enters the axis of this cylinder, perpendicular to the plate, and the magnetic circuit is made in the form of two cores, pressed into the hollow cylinder at its ends, so that the longitudinal axis of the cores coincides with the plane of application of forces, while the excitation windings measuring each formed. two sections located on both 1Q cores, with the field winding sections connected in parallel, and the measuring coil sections connected in series and counterclockwise. 2. The dynamometer according to claim 1, in that, in order to regulate the initial signal of the measuring winding, the fixing plate is movable along the axis of the cylinder.