RU2435137C1 - Elastic gimbal - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: in an elastic gimbal, having a movable and a fixed part joined by elastic crosspieces in form of beams, two lines for fixing the beams, which are in the movable and fixed parts of the elastic gimbal, wherein the beams come of the centre of the figure formed by lines for fixing the beams to lines for fixing the beams and are at an angle to each other, the number of beams m is at least 5. The section of the beams along the working length remains constant or changes by not more than 25%, rigidity to longitudinal bending c₀ of the m-beam elastic gimbal with identical beams with a constant section lying at equal angles to each other is determined by the formula:

(1), where E is the modulus of elasticity of the material of the beam; b is the width of the beam; h is thickness of the beam; L is the length of the beam.

EFFECT: invention enables to reduce sensitivity to external effects and increase the range of effects on a dynamically adjusted gyroscope while preserving its accuracy and reliability.

2 cl, 5 dwg

Description

The invention relates to the field of gyroscopic technology, namely to elastic suspensions of sensitive elements of dynamically tuned gyroscopes (DNG), and can be used in any primary information sensors.

In modern dynamically tuned gyroscopes, an obligatory component is an elastic suspension (UP) connecting the sensing element to the universal joint.

As is known, the sensitive element of the DNG gyroscopes performs continuous oscillation at its resonant frequency, gaining a huge number of deformation cycles during the operation of the device.

The angular and linear displacements of elastic elements decrease the accuracy of DNG, which leads to a redistribution of reactions in the suspension, a shift in the center of mass of the suspension, and the appearance of disturbing moments.

The following technological defects in manufacturing have the greatest impact on the accuracy of DNGs:

- the rotation of the elastic jumper around its longitudinal axis;

- lateral displacement of elastic jumpers;

- displacement in the longitudinal direction;

- twisting deformations of the jumpers when fastening (for non-monolithic structures) in the unitary enterprise (Pelpor DS and other dynamically tuned gyroscopes: Theory and design. - M.: Mechanical Engineering, 1988, pp. 128-155).

Known elastic suspension dynamically tuned gyroscope containing two bushings with elastic jumpers, which are formed by two adjacent holes (US patent N 3700289, NKI 308-2A, 1970), which is most widely used in instrumentation for its simplicity, reliability and manufacturability.

A disadvantage of the known suspension is the large non-equal rigidity of the suspension at various movements along the axes of insensitivity and the resulting lack of accuracy of the gyroscope.

Closest to the proposed device is the device according to the patent (RU No. 2064662, G01C 19/22, 1996). In a dynamically tuned gyroscope UE, the elastic jumpers in one of the UE parts forming the suspension are rotated by an angle of 15-30 degrees from the direction perpendicular to the jumpers in the other part of the UE, and the movable and fixed UE parts are made with protrusions for mutual fixation. Elastic jumpers are formed by two adjacent holes (Fig. 1, a). On each side of the movable and fixed part of the unitary unit, two jumpers are directed at an angle to each other.

The disadvantage of this device is the complexity of the manufacturing process and not high enough maximum load along the axes of insensitivity.

The main characteristics of an elastic suspension are:

- minimum rigidity along the axis of sensitivity,

- maximum rigidity along the axes of insensitivity,

- the maximum value of the permissible load during mechanical stress.

When developing a DNG, the choice of the structural design of elastic supports and their elastic elements is very important. The cross-sectional shape of the UP beam is usually rectangular.

To compare the characteristics of the suspensions with respect to the maximum rigidity along the axes of insensitivity and the maximum value of the permissible load during mechanical stresses, it is necessary that the UE have the same length, width and longitudinal bending stiffness.

The objective of the invention is to reduce the sensitivity to external influences and increase the range of effects on the DNG while maintaining its accuracy and reliability.

This goal is achieved by the fact that in the elastic suspension of the gyroscope containing the movable and fixed parts of the elastic suspension connected by elastic jumpers made in the form of beams, two lines of sealing beams located on the movable and fixed parts of the elastic suspension, the beams come out from the center of the figure formed by the lines embedment of beams, to the embedment lines of beams and are at an angle to each other, the beams can have rounding radii in the places of their embedment, the number of beams m is at least 5.

In addition, in an elastic suspension, the cross-section of the beam throughout the working length remains constant or changes by no more than 25%, the longitudinal bending stiffness from the ₀ m-beam elastic suspension with the same beams with a constant cross section, at equal angles to each other, is determined from the equation:

the maximum number of beams of the m-beam elastic suspension with the same beams at equal angles to each other is found from the following inequality:

the optimal number of beams of the m-beam elastic suspension with the same beams at equal angles to each other, for an increased maximum load, is found by the following formula:

where E is the modulus of elasticity of the material of the beam;

b is the beam width;

c ₀ - longitudinal bending stiffness;

L is the length of the beam.

UP with several beams (Fig. 1, b, c, d, e, f, g) is two lines for sealing beams, for example, in the form of semicircles located on the movable and fixed parts of the UP and connected by beams extending from the center of the figure, formed by the lines of embedment of beams, to the lines of embedment of beams. The loads arising from mechanical action are distributed between several beams, which allows to increase the rigidity and the maximum load UE on the axes of insensitivity while maintaining constant rigidity on the axis of sensitivity.

The invention is illustrated by drawings.

Figure 1 shows the configuration options of the elastic suspension, where:

a - unitary enterprise with a beam of variable section;

b - four-beam unitary enterprise;

in - five-beam unitary enterprise;

g - six-beam unitary enterprise;

d - seven-frame UP;

e - eight-beam unitary enterprise with a radius of rounding in places of embedment of the beam;

g - UP with beams of various sections, working lengths and various angles between the beams.

Figure 2 - arrangement of the beam for various types of deformation of multi-beam UP, where:

a - arrangement of the beam at rest;

b - beam arrangement in longitudinal bending;

in - the arrangement of the beam with transverse bending;

g - beam arrangement in compression.

Figure 3 - graphs of the ratio of the stiffness of the elastic suspension of various configurations, where:

a - the ratio of the stiffness of the UP on the transverse bending;

b - the ratio of the rigidity of the UP torsion;

in - the ratio of stiffness UP compression;

g - the ratio of the stiffness UP on a longitudinal shift;

d - the ratio of the stiffness UP on the transverse shear.

Figure 4 - graphs of the ratio of the stiffness of the axes of the elastic suspension of various configurations, where:

a - the ratio of the stiffnesses of the axes of the UP on the transverse bending;

b - the ratio of the stiffnesses of the axes of the UP to torsion;

in - the ratio of the stiffnesses of the axes of the UP compression;

g - the ratio of the stiffnesses of the axes of the UP on a longitudinal shift;

d - the ratio of the stiffnesses of the axes of the UP on the transverse shear.

Figure 5 - graphs of the relationship of the maximum internal stresses in the beams UP and axes UP with beams of variable cross-section and several beams, where:

a - the ratio of the maximum internal stresses in the UP beams with beams of variable cross-section and several beams with a maximum number of beams in the embedment line equal to 1000;

b - the ratio of the maximum internal stresses in the UP beams with beams of variable cross-section and several beams with a maximum number of beams in the embedment line equal to 10;

c - the ratio of the maximum internal stresses in the beams of the UP axes with beams of variable cross-section and several beams with a maximum number of beams in the embedment line equal to 1000;

g is the ratio of the maximum internal stresses in the beams of the UP axes with beams of variable cross-section and several beams with a maximum number of beams in the embedment line equal to 10.

The elastic suspension (Fig. 1, b, c, d, e, f, g) consists of two lines of embedment of beams located on the movable 1 and motionless 2 parts of the unitary assembly and connected by beams 3 that extend from the center of the figure formed by the embedment lines of the beams . The loads arising from mechanical action are distributed between several beams, which allows to increase the rigidity and the maximum load UE on the axes of insensitivity while maintaining constant rigidity on the axis of sensitivity. To simplify those. the manufacturing process and reduce the voltage at the junction of the beam with the embedment lines of the beams located on the movable 1 and fixed 2 parts of the unitary enterprise, and between the beams 3 can be made radii of fillet (figure 1, e).

), на каждой из линий заделки, одинаковой рабочей длиной балки и одинаковыми углами между балками, как показано на фиг.1,б, г, е. Далее рассматривается УП данной конструкции.The number of beams connecting the central and movable part of the unitary enterprise, and the number of beams connecting the central and stationary part of the unitary enterprise, the working length of the beams and the angle of inclination between the beams of such a design of the unitary enterprise can be different. But with such a design of the unitary enterprise (Fig. beams (

), on each of the embedment lines, with the same working length of the beam and the same angles between the beams, as shown in Fig. 1, b, d, e. Next, the UE of this design is considered.

For a more uniform load distribution, the cross section of the working length of the beam (G) can vary up to 25%, to achieve maximum rigidity along the axes of insensitivity, the cross section of the beam along the working length should remain constant, and accordingly, we will further consider UE with a beam of constant cross section and without radii fillets.

To compare the characteristics of the suspensions with respect to the maximum rigidity along the axes of insensitivity and the maximum value of the permissible load during mechanical stresses, it is necessary that the UE have the same length (L), width (b) and longitudinal bending stiffness (c ₀ ).

If we consider the values of the angles of deviation UE β, φ and ξ as extremely small, then with a longitudinal bend of UE the angle of inclination of the beam is equal to (Fig.2, b):

when the transverse bending UP (figure 2, c) the angle of transverse bending of the beam is equal to:

φ _i = φcos (α _i ),

the torsion angle of the beam is:

ξ _i = φsin (α _i ),

when torsion UP, the angle of transverse bending of the beam is equal to:

φ _i = φsin (α _i ),

the torsion angle of the beam is:

ξ _i = φcos (α _i ).

Similarly, when δ, γ and σ << L, when compressing the unitary enterprise (Fig.2, e), the compression ratio of the beam is equal to:

δ _i = δcos (α _i ),

the longitudinal shift of the beam is equal to:

γ _i = δsin (α _i ),

with a longitudinal shear UP, the longitudinal shear of the beam is:

γ _i = γcos (α _i ),

the beam compression value is

δ _i = γsin (α _i ),

in transverse shear, the transverse shear of the beam is

σ _i = σ.

Based on the expression (4) the thickness of the beam n-beam UP (figure 1, g) is determined from the equation:

where E is the modulus of elasticity of the material of the beam;

b is the beam width;

h is the thickness of the beam;

L is the length of the beam;

where from:

,Where

,

The maximum number of beams as c ₀ → 0 is determined from the inequality

Since, as c ₀ → 0, ctg (π / 2n) → 2n / π, inequality (5) takes the form:

Where

where from:

From the above equations it follows that the stiffness of the n-beam unit under various influences is equal to:

- with longitudinal bending,

- with transverse bending,

- during torsion,

- during compression,

- with a longitudinal shift,

- with transverse shear.

Since two UPs are usually located on one axis of a unitary unit, the rigidity coefficients of the unitary unit axis are equal to:

G _β = 2g _β

- stiffness of the axis in longitudinal bending;

G _φ = 2 (cos (θ / 2) g _φ + sin (θ / 2) g _ξ + cos (θ / 2) r ² g _δ + sin (θ / 2) r ² g _γ )

is the stiffness of the axis during transverse bending, where θ is the angle between the symmetry axes of the UE in the axis (as a rule, θ = 0), r is half the distance between the UE (usually r> L);

G _ξ = 2 (cos (θ / 2) g _ξ + sin (θ / 2) g _φ + cos (θ / 2) r ² g _γ + sin (θ / 2) r ² g _δ )

- stiffness of the axis during torsion;

G _δ = 2 (cos (θ / 2) r ² g _δ + sin (θ / 2) r ² g _γ )

- stiffness of the axis during compression;

G _γ = 2 (cos (θ / 2) r ² g _γ + sin (θ / 2) r ² g _δ )

- stiffness of the axis during longitudinal shear;

G _λ = 2g _λ

- stiffness of the axis during transverse shear.

The dependences of the stiffnesses of the UP axis for a different number of beams in the UP and for the axis of the UP with a beam of variable section are shown in Figure 4 (G0 is the stiffness for the axis with beams of variable section, where θ = 90 °, at which the axis of the UP with a beam of variable section has the same stiffness along the axes of insensitivity).

The voltage in the beam at a load of M ₀ (F ₀ ) is determined based on the expression:

where F _op - the reaction force of the support arising in the beam,

S _b - the area of the beam.

Since under the load M ₀ (F ₀ ) acting on the control unit, a deformation equal to M ₀ / g occurs, expression (6) takes the form:

- when bending or torsion,

- during compression or shear, where g _b is the beam stiffness, l is the moment arm.

Given that the beam is at an angle α to the line of action of the load, equations (7) and (8) will take the form:

- during compression or shear, or:

- with transverse bending or torsion. The dependences of the internal stress in the beam are shown in Fig. 5, a, b, which shows that the maximum value of the internal voltage arises in the beam along the line of action.

The dependences of the maximum stresses in the UP beams, obtained according to (7) - (10), on the number of beams are shown in Figs. by increasing the number of beams or when bending has a minimum if the number of beams satisfies the expression:

The maximum load on the UE is determined based on the value of the ultimate internal stress of flexibility of the material (if the internal stress is higher than the maximum internal stress of flexibility, irreversible deformation of the UP occurs). From the expressions (5) - (8) it can be seen that the magnitude of the maximum load is inversely proportional to the ratio of internal stresses arising from the same impact, as shown in Fig.5.

Thus, the number of beams of the axis of the elastic suspension, consisting of a pair of UEs at a distance, should be n _max according to (2), the number of beams of the elastic suspension, consisting of one UE, should be n _opt according to (3). This will increase the allowable load for the primary information sensors, which will lead to a decrease in sensitivity to external influences and an increase in the range of effects on the primary information sensors while maintaining their accuracy and reliability.

Claims (2)

1. The elastic suspension of the gyroscope, containing the movable and stationary parts of the elastic suspension connected by elastic jumpers made in the form of beams, two lines of embedment of beams located on the movable and fixed parts of the elastic suspension, and the beams extend from the center of the figure formed by the embedment lines of the beams to the lines embedment of beams and are at an angle to each other, the beams can have radii of rounding at the places of their embedment, characterized in that the number of beams m is at least 5. 2. The elastic suspension according to claim 1, characterized in that the beam cross section remains constant during the working length or changes by no more than 25%, longitudinal bending stiffness from a ₀ m-beam elastic suspension with identical beams with a constant cross section under equal angles to each other, is determined from the equation:

the maximum number of beams of the m-beam elastic suspension with the same beams at equal angles to each other is found from the following inequality:

the optimal number of beams of the m-beam elastic suspension with the same beams at equal angles to each other, for an increased maximum load, is found by the following formula:

where E is the modulus of elasticity of the material of the beam; b is the beam width; h is the thickness of the beam; c ₀ - longitudinal bending stiffness; L is the length of the beam.

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