RU1793384C - Angular acceleration sensor - Google Patents

Abstract

| The invention relates to information measuring equipment and can be used; Used to measure the angular accelerations of technical objects during their testing and operation. SUMMARY OF THE INVENTION: the device consists of a 0-shaped magnetic core 1 having a circular section 3 on the shaft 2, serving as an axis on which the inertial mass 4 is mounted, which is a soft magnetic ring whose radial thickness is constant and the external the generator varies in a circular fashion according to a linear law. Additional non-magnetic masses 5 and 6 are used to balance the inertial element 4. The gap between the inner surface of the annular mass 4 and the circular section 3 is filled with a magnetic fluid 7.4 silt.

Description

The invention relates to measuring technique and can be used to measure the angular accelerations of technical objects during their testing and operation.

A known angular acceleration sensor comprising a 0-shaped magnetic circuit, inertial elements in the form of permanent magnets connected to the moving part of the sensor by flat springs, and a measuring winding.

The disadvantages of this sensor are a narrow measuring range as a result of the small amplitude of the inertial mass deviation from the equilibrium position and low reliability due to the presence of elastic deformable elements.

An angular acceleration transducer is also known, comprising a magnetic circuit, an alternating current excitation winding, a measuring winding, and a sector-shaped magnetic soft inertial mass planted on a diamagnetic axis.

The disadvantage of this converter is the presence of a large number of various and complex in shape parts of the magnetic circuit, which determines the structural complexity of the device.

Closest to the proposed technical essence is an angular acceleration sensor containing a magnetic circuit with DC excitation windings and measuring windings simultaneously springs placed on it and an annular inertial mass on the magnetic axis.

The specified converter has a complex design. This is explained by the large number of assembly parts. In addition, a spring winding made of special grades of steel and requiring flexible insulation has a complicated manufacturing technology to avoid shorting the coils to the housing and to each other. The use of such a winding in the sensor complicates its design by the problem of fixing the central part of the dummy yarn on the inertial element. The disadvantages of this device also include difficulties associated with the output of the current-carrying and signal wires of the windings located inside the cylindrical body. In addition to the listed disadvantages that determine the complexity of the design of the converter,

its reliability is reduced due to increased wear of the spring windings.

The purpose of the invention is to simplify the design and increase the reliability of the sensor

The goal is achieved in that in an angular acceleration sensor containing a magnetic circuit with DC excitation windings and measuring windings located on it and a ring inertial mass on the magnet of a flexible axis, the outer forming the ring inertial mass is made to vary in a circular fashion according to the linear law

0 to the circular section of one of the rods of the 0-shaped magnetic circuit, the gap formed by the circular section of the rod and the inner surface of the annular mass is filled with magnetic fluid, and non-magnetic inserts were used to balance the annular inertial mass.

Comparative analysis with the prototype showed that; The inventive device differs in that the inertial mass of the outer forming ring is made to vary in a circular fashion according to the linear law, the mass is transferred to a circular section of one of the rods of the 0-shaped

5 of the magnetic circuit, the gap formed by the round section of the rod and the inner surface of the annular mass being filled with magnetic fluid, and non-magnetic inserts were used to balance the inertial mass. As a result of a patent search and a search in the scientific and technical literature, no technical solutions were found that have features similar to the S-distinctive features of the claimed device. Therefore, the claimed solution meets the criteria of novelty and significant differences.

In FIG. 1 shows a design of a sensor; in FIG. 2 - the appearance of the inertial mass without nonmagnetic inserts; in FIG. , 3 - graph-output EMF under the influence of constant angular acceleration in one direction; Fig. 4 is a graph of the output .EMF under the influence of a constant accelerator5 or in the opposite direction.

The angular acceleration sensor contains a 0-shaped magnetic circuit 1 having a circular section 3 on the rod 2 and serving as an axis on which an inertial mass 4 is fitted. Mass 4 is a ring of magnetically soft material whose radial thickness is constant and the external the forming ring varies in a circular fashion according to a linear law

5b „

B

Jm3kc

1l

and,. About 2 p.

(D

where b is the value of the generatrix;

Lmax is the largest value of the generatrix (see Fig. 2);

about. is the magnitude of the angle, the function of which is the outer forming annular assa, or the angular displacement of the inertial mass.

Various values of the outer forming ring are indicated in FIG. 1 as bi and b2. Олнительн Extra masses 5 and b, made of non-magnetic material, are used to balance the inertial mass 4. The gap between the inner surface of the face mass 4 and the circular section 3 of the rod 2 is filled with magnetic fluid 7. Field windings 8 and 9. The magnetic conductors located on the rods 1 are connected in series and counter-current and are supplied with direct current. A measuring coil, ie, windings 1.0 and 11, which are connected in series and in accordance with the output EMC, are also located on the magneto-electrodes 1.

The sensor operates as follows.

When the test object is rotated at a constant speed, mass 4 is at rest of the carrier magnetic circuit 1 and the output

and

drove equal to zero.

When angular acceleration appears, M.iccy is affected by a torque that causes the inertial mass 4 to rotate at a constant angular velocity, or defined from the d'Alembert principle as

L1 - d.g - M

"T, (2)

where about.-angular displacement of inertial mlssa;

M - torque;

f is the coefficient of friction constant rotation of the mass of the 4-axis.

Wherein

M 1 r.

Koi J of circular cross section and inner surface of the ring 4, which is filled

where lo is the moment of inertia of the body:

. p is the angular acceleration of the investigated object.

The rotation of the inertial mass 4 leads to a change in the area of the air gap of thickness b (see Fig. 1) between the outer surface of the annular mass and the longitudinal rod of the magnetic circuit 1.

The magnetic resistance of the steel of the magnetic circuit, as well as the gap between the

ma

gnitic liquid 7, neglected because of their smallness compared with the resistance of the air gap with a thickness of d. For an absolute flow of the sensor, 55

Ф -тЈ-, (4)

R

/

where F is the DCS of the DC excitation windings;

5 10

fifteen

twenty

25

thirty

35

40

45

fifty

55

Rj {is the magnetic resistance of the air gap of thickness d and area S.

(5)

where q is the magnetic permeability of air.

Since the external generating annular inertial mass varies in a circle (in other words, as a function of a) according to the linear law (1), the dependence of the gap area on the rotation angle of the mass is also linear:

S Ki + K2 a. (6) where Ki, K2 are constant coefficients in magnitude.

When the magnetic flux changes in the measuring coils 10 and 11, an EMF is induced, the expression for which is obtained from condition (4), taking into account equations (5) and (6):

 ,.; d IA / s K2 ,, v

f-ism - - W - W F -g- -at. (7)

where W is the total number of turns in the coils 10 and 11.

We substitute formula (3) into expression (2). and the resulting equation in (7). Differentiating, taking into account the constant value of the acting acceleration, we obtain

IO // Q K2

Јand

 -W F

It follows from the obtained that when the inertial mass 4 rotates at a speed proportional to the acting acceleration, the emitter emits at the sensor output. also proportional to the acceleration of the controlled object.

The output of the sensor is determined by the speed of rotation of the mass, which depends on the magnitude of the effect. In this case, deformable elements are excluded, which simplifies the design and makes it more reliable. The implementation of such a mode of operation of the device is achievable as a result of performing an external generatrix of the annular mass varying in a circular fashion according to a linear law.

A further simplification of the design of the transducer is to fit the inertial mass onto a circular section of one of the rods of the 0-shaped magnetic circuit. In this case, the portion of the core of the magnetic circuit simultaneously functions as an axis and there is no need to use the corresponding part.

Filling the gap between the circular cross section of the rod of the 0-shaped magnetic circuit and the inner surface of the annular mass with magnetic fluid is necessary to obtain a small magnetic

resistance of this air gap and thereby ensuring high linearity of the converter output signal.

The most stable operation of the proposed sensor, taking into account new features, is ensured by the application of 4 additional masses made of non-magnetic material to the inertial element.

The proposed technical solution has an additional advantage with respect to the prototype, namely, when the inertial mass 4 rotates, in the output signal of the sensor, in addition to the analog component, there are also negative surges in the output voltage (see fmg. 3 and 4). This negative emission is explained by the presence in mass 4 of a sharp drop in the magnitude of the external generatrix from the maximum to the minimum value. One pulse corresponds to one complete revolution of the annular mass, and the time interval between two adjacent surges is equal to T, the period of revolution of the inertial mass. The number of pulses n per unit time, proportional to the acting acceleration, is determined.

: - TD +

The possibility of simultaneously receiving the sensor output signal in analog and discrete form allows its universal use in both analog and digital measuring systems. If you want to get rid of the discrete component of the signal, the sensor output is shunted by the capacitance.

Free rotation

the inertial mass on the axis, unlimited by the largest angle of rotation of the spring, provides two additional advantages relative to the prototype:

the range of the device in the direction of increase and the ability to measure external influences for an unlimited time, i.e. the larger the angular accelerations affect the inertial mass, the proportionally greater speed it is able to rotate during the arbitrarily long exposure to the acceleration.

Indicated advantages of the claimed

Technical solutions determine the economic and practical feasibility of its use in measurement, control and control systems.

Claims (1)

The claims An angular acceleration sensor comprising an annular inertial mass and a magnetic wire with DC excitation coils and measuring windings located on it, characterized in that, in order to increase reliability, the magnetic core is made 0-shaped with a circular section of one of the rods on which it is mounted ring inertial mass, consisting of a magnet of a soft element and two non-magnetic elements, and the section of the magnet of the soft element varies linearly from the maximum section of the ring to zero around due to a change in the thickness of the ring symmetrically from the side of both ends of the ring, and non-magnetic elements are made in the form of inserts, supplementing the ring to the full volume, while the gap between the inner surface of the annular inertial mass and the circular cross section of the rod is filled with magnetic fluid. Јuj " V Riga.Z t-iy. t Uh.Ch  /  9m g T