SU705347A1 - String accelerometer - Google Patents

Description

(54) STRING ACCELEROMETER

linear expansion of the body material.

The drawing shows a string accelerometer.

The string accelerometer contains two single-string systems, each of which contains a housing 1 with an elastic suspension 2 fixed at one end. The second end of the elastic suspension enters the inner opening of the inertial mass 3, made in the form of a 1 cylinder. The elastic suspension coaxially is located with the string 4, one thickened end of which is associated with an elastic suspension, and the second thickened end 5 - with the body. Between the inner surface of the protrusion of the inertial mass and the outer surface of the protrusion 6 of the body placed a drop of 7 non-drying damping fluid, for example, kremneorganicheskogo. The string is placed in the gap of the magnetic system 8, which is used to excite and eat the oscillations of the string. The body of the single-jet system is installed in the additional base 9 between the protrusion 10 and the bar of the clamping element 11. The body of the single-stranded system is pressed through the bar of the clamping element by the locking arm 12 connected to the second protrusion 13 of the additional base. By turning the screw 12

the housing of the single string system 1 is compressed. The compression of the body leads to a change in its geocutric dimensions and, of course, reduces the tension of the stringers 4. The direction of the compression force

on the axle strings. Because of this

The total tension of the string is two cri | i: the pretension force and the compression force.

Under the influence of temperature r, the lengths of the accelerometer case, suspension, string, and additional base are changed. Since the values of the thermal expansion coefficients of the accelerometer case and the additional base are different, as the temperature changes, the difference in elongations appears. Due to this difference, the tension of the string increases, since the accelerometer case is a compressed spring. The stiffness of this spring is much larger than the suture string. Therefore, when resizing, the compressed spring closes, the force developed by the spring expands the spring. The force arising in the string from the temperature, and from lengthening the body, has different voltages, as a result, the tension and the frequency of the vibration of the string remain in the string ..

Typically, in a string accelerometer, the length of a string B with less than the length

705347

case C, let the temperature coefficient of linear expansion of the body oCjj be less than or equal to the temperature coefficient of linear expansion of the dip dip, then under the influence of the temperature increment & , according to Wits, the difference in elongations is:

) H

(one)

 in this case, the tension is determined by expression;

T TO - TH,

lt

where is e

elastic modulus of the string material;

S is the cross-sectional area of the string;

Tfj is the initial tension before temperature. As we see, the effect of temperature leads to the appearance of a temperature tolerance determined by the second term in expression (2).

At the same time, the length of the additional base Cd is longer than the length of the accelerometer case, and putting for definiteness that the temperature coefficient of linear expansion of the additional base of оСо is greater than or equal to the temperature coefficient of linear expansion of the accelerometer case, then under the influence of temperature, the difference in extensions is:

c a-Vd-oeo- - eK

(four)

Due to the preliminary compression of the case by the force of the clamping element, the length of the string changed by the magnitude of the DC, which is equivalent to the change in the tension force on the DT, defined by the expression:

-.

(five)

The string accelerometer case in this case is a compressed spring. However, under the action of temperature, when the elongation is determined by expression (3), the tension of the shaft should increase by the amount of:

V-Tr4 "-oV -KV-- |: - (6).

h ss.

This tension reduces the temperature frustration. Equating to expressions (3) and (6), we require that the change in string tension from temperature changes be zero, i.e.:,. (7)

Substituting the expressions corresponding to these values and transforming them, we have:

(eight)

Claims (2)

cc from the expression obtained it is easy to divide the range of temperature variation at kOTOpoM, a decrease in temperature error occurs. To reduce the temperature variations, the string accelerometer case is pressed by force, which causes a decrease in the length of the string by A.t. The force of pressing the case of the string accelerometer N can be easily determined by the expression: the modulus of elasticity, SK where E, the cross sectional area and the length of the corpus of the string accelerometer, respectively. The use of the additionally introduced base favorably distinguishes the prepacked string accelerometer from the specified prototype, since it changes the initial tension of the string and allows you to set the range of variation of the external temperature, in which the temperature error should be reduced. The change in the initial tension during tests showed that it is possible to set the initial tension (10) with an accuracy of up to 10 relative values. Claim 1. String accelerometer, comprising a housing, an inertial mass and a string associated with them, characterized in that, in order to improve the measurement accuracy by lowering the temperature error, a base is inserted in it, made with two protrusions, one of which is pressed against the housing Accelerometer, and between the second protrusion and the opposite side of the body is placed clamping unit, the force of which is directed along the axis of sensitivity of the accelerometer. 2. Accelerometer pop. 1, characterized in that the base is made of a material whose temperature coefficient of linear expansion is equal to or different from the temperature coefficient of linear expansion of the material of the body. VfcTo4HHKH information taken into account during the examination 1.Novitsky P.V. and others. Digital devices with frequency sensors, Energie, L., 1970, p.125. 2. Authors certificate of the USSR 452787, cl. G 01 P 15/10,. (prototype).