SU869570A3 - Electric generator with series excitation circuit - Google Patents

Abstract

The resonator is inserted in a loop which includes a variable tuning capacitance. The variable tuning capacitance may contain one variable capacitor or more than one variable capacitor. The oscillator has a mechanical device which responds to an acceleration applied to the oscillator. It so controls the variable capacitor (10, C3), that the frequency change so produced is equal and opposite to frequency change caused by acceleration application to the resonator.

Description

(54) ELECTRIC GENERATOR

The invention relates to the field of electric generators with piezoelectric resonators and can be used as frequency reference standards for synchronizing signals in air or space vehicles. Known electrical generators containing piezoelectric resonators 1. Their disadvantage is the low frequency stability of electrical oscillations. A known electric generator with a series of excitation oscillation circuit comprising a capacitance regulating the oscillation frequency, consisting of at least one variable capacitor, one plate of which is connected to the output of the circuit, a piezoelectric crystal, one of the terminals of which is connected to another plate of the capacitor, and an amplifier whose input is connected to another resonator terminal, the output of which is connected to the output of a series circuit, and a matching circuit. the level of the oscillation signal sent by this circuit, connected by its input with the output of said circuit 2. The disadvantage of this generator is the low stability of the frequency of electrical oscillations under the action of acceleration. The purpose of the invention is to improve the stability of the frequency of electrical oscillations under the action of acceleration. This goal is achieved by the fact that the generator contains a device that is sensitive to acceleration to which the generator is mechanically connected with the fixed and movable fittings of a variable capacitor according to the degree of freedom of movement; the acceleration sensitive device may be an elastic return element of the movable reinforcement according to the degree of freedom of movement; the variable capacitor can have a variable distance between the plates, and the elastic return element consists of flexible plates, which are fixed on the reinforcement installed in parallel and with the possibility of moving towards the fixed reinforcement of the variable capacitor .I In addition, in such a generator the direction of movement The moving armature of a variable capacitor can be parallel to the acceleration sensitivity vector. a piezoelectric crystal of the resistor, and the variable capacitance may consist of three variable capacitors, which contain each device sensitive to acceleration and to the elastic return of their moving armature, which are electrically connected in parallel with each other and in series with the resonator, and the directions of movement movable armatures of which are respectively parallel to the three main axes of the piezoelectric resonator crystal.

The proposed oscillator can have two versions. In the first embodiment, one of the variable capacitor plates has profiled edges between the straight lines perpendicular to the direction of movement of the movable plate, and the other variable capacitor plate has a rectangular surface.

In the second embodiment, the elastic return element consists of a flexible plate mounted on movable reinforcement, which is movable at a constant distance from said fixed reinforcement and in a direction parallel to the surfaces of the plates.

In the first and second versions, the said profiled edges are each determined by the following relation of the profile P depending on the movement and the moving armature.

 Mu-K) where A is constant, dependent on the geometric and mechanical parameters of the named elastic element and the named variable capacitor;

K is constant, depending on the named geometrical and mechanical parameters, as well as on the opposite surface of the named reinforcement with zero acceleration and other capacitances of the named generator.

Fig. 1 shows an electrical circuit of a piezoelectric resonator and its variable capacitance; in figure 2 a piezoelectric crystal in a perspective view. and its main axis; in fig. 3 shows the accelerator compensating acceleration according to the first embodiment, half-section on the right in FIG. 4 - the same, top view; in fig. 5 g capacitor diagram in axonometry compensating the acceleration according to the second embodiment; in fig. 6 is a cross section on the front side of the fixed plate of the capacitor shown in FIG. five; in fig. 7 shows the profile shape of the transverse edges of the fixed plate; in fig. 8 shows the arrangement of three variable capacitance capacitors of the capacitor according to the first embodiment, when the acceleration sensitivity vector is unknown; in fig. 9 is the same according to the second embodiment.

The electric generator contains a series circuit consisting of a variable capacitor 1, one of the plates of which is connected to the output 2 of the circuit, a piezoelectric quartz resonator 3, one of the clamps of which is connected to another plate of the capacitor 1, and an amplifier 4, the input of which is connected to another clip resonator, and the output of which 5 is associated with the output of circuit 2. The circuit b, the input of which is connected to the output 2 of the circuit, provides for matching by the level of the vibration signal transmitted via the output 2 of the circuit, which it transmits via its output 7 to other circuits or organs. The vector g, shown in one of the directions, represents the acceleration to which the generator is subjected, and the purpose of which is to compensate for the effects by automatically changing the capacitance C of the variable capacitor 1.

FIG. 2 shows a piezoelectric crystal 8 of the resonator 3 and all three of its main axes, which are designated OX, OU and OZ. Crystal 8 is, for example, quartz in the AT cut. Such a cut is known to provide maximum frequency stability and minimal sensitivity to temperature changes. To ensure maximum resonance, face 9 of chip 8 is a spherical segment, the convexity of which is oriented in the direction of.

Changes in the dP frequency of such quartz in different directions in the directions of their main axes were determined experimentally by changing the number of attachment points on the holders (not shown in Fig. 2) at different acceleration values. It was found that in all cases the change in frequency (hertz) in both directions with respect to the nominal frequency, which is determined by the frequency at zero acceleration, can be expressed using the following equation:

,, 4К2Гг, (1)

where rj, r2. - the corresponding projections of the acceleration vector for all three

main axes, 04 and 02;

ttx, K, and kz are the proportionality coefficients of a given resonator, which are almost constant in a given range of acceleration values.

0 as an example for AT quartz, indicated viiie, the nominal oscillation frequency of which is 5.10 Hz, was found:.,. Kch 10-K; 2 .. 1SG

5 at acceleration values of -50s (up to + 50qr. Coefficient, K, K2 are expressed in hertz per unit of acceleration of the earth's attractiveness (Hz / s). It should be noted that equation (1) is an unfolded scalar where: is the acceleration vector and K is the vector expressing the modulus and direction of the acceleration sensitivity of the given resonator. The consequences of this will be derived in the future. Turning again. 1, note how the oscillation frequency of the resonator 3 can be adjusted by connecting the bones in series. The equivalent electric circuit of the resonator 3 and the structure of the variable rectifying capacitor 1. A series resonant circuit consisting of resistance I, coil and ductivity L and capacitor C, equivalent to a piezoelectric crystal and capacitor D o, has a capacitance between the electrodes. It is necessary to remind that the LR frequency shift, caused by the inclusion of capacitance C, is expressed by the following equation: - l (, as an example for such a square, which has already been considered and which has in the nominal oscillation frequency equal to F 5 Hz, assume the following approximate values: C, 10 F R. 100 Ohm U 10 Hn to 4. If capacitance C is higher, h capacitance CQ, equation (3) becomes in the first approximation: Indeed, in order to provide accurate frequency correction, capacitor 1 of capacitance C should consist essentially of two parallel connections s, one with capacity C and another variable with capacity C, and the capacity Cf is significantly larger than capacity C. In this case, equation (4) takes the following form: iL cP 7 () (5) and the corrective sensitivity becomes then: dlftF) -uT About d (uPb-dCn, (7) Thus, the foregoing proves suitable The present construction: a variable capacitor connected in series with a resonator and means of regulating the capacitance of this capacitor according to the acceleration value to compensate for changes in the frequency of said resonator caused by said acceleration. You can, for example, adjust the geometric parmeter within the degree of freedom of movement {surface or distance between the plates), which affects the variable capacitance of the capacitor according to the magnitude of the signal sent by the sensor Oren The invention provides a simple and effective solution, koto-Roe consists in the possibility of the sensor being connected to the variable capacitor by attachment of its mobile plate via elastic return body. According to the first embodiment of the invention, taking for M the mass of the movable plate and for X the rigidity of the return spring, a linear change in the parameter is observed depending on the acceleration. In terms of sensitivity to acceleration and in order to facilitate manufacture, the distance between the plates is taken as an adjustable parameter. As for the elastic return means, it is possible, for example, to use a volume of gas enclosed between the plates and a hermetic elastic shell. However, it is much easier to apply a suspension on elastic plates, such as shown in FIG. 3 and 4. The fixed fittings 10 of the capacitor capacitor C.IJ are glued to the insulating base 11; the continuation of which is the shoulder 12. The movable reinforcement 13, parallel to the reinforcement 10, is a plate made of an elastic conductor of a conductive material, for example, from a nickel alloy, the continuation of which are two plates 14 ,. having stiffness X that hang over the shoulder 12 and in which longitudinal grooves 15 are made. The locks 16 clamp the shoulders 12 and support the plates 14 in the slots in which they are inserted with threaded ends 17 on which the BcUOTCH screws 18 are screwed. Plate 19 from insulating material it is glued to the reinforcement 13 and serves as an additional weight load M. The reinforcement plates 10 and 13, respectively, are connected by conductors 20 and 21, passing through elements 11 and 19 to terminals 22 and 23. The variable capacitance Cd, of the capacitor, whose structure is shown in FIG. 3 and 4, is expressed according to the KJiaccH4e formula: since eo-ygde 9, Q is the dielectric constant of vacuum, equal to 8.84. S surface resistance

fittings;

t is the distance between the armatures. Since the mechanical connections are symmetric, S practically does not change only AND varies linearly with y; If the direction of the vector V. is known, for example, as a result of a preliminary determination of the coefficients K), K and K. Cheers in (1), a capacitor is obtained, the plates of which are perpendicular to the said vector.

According to equation (8), the value of component 7 in the direction K is such that it causes a change in M of the distance t and leads to a change in the capacitance; g

ac.-t- (9)

and cJCj -cie (10)

But with a given weight of load 19 (the weight of plate 13 is not taken into account) and a given stiffness X flexible springs consisting of plates 14:

, (eleven)

from where dCnj-v-r (12)

Thus, comparing equations (7) and (12), we see that:

d (uP) - olC -r (13)

Consequently, it is possible to obtain using a variable capacitor on an elastic suspension (Figs. 3 and 4), by determining its geometric and mechanical parameters (distance between reinforcement, contact surface, stiffness-plates), respectively, due to the design or regulatory bodies (not shown on Figs. 3 and 4) practically accurate compensation of the shift in frequency caused by acceleration by acting on the generator.

According to a second embodiment of the invention, the compensation for the frequency shift caused by the acceleration to which the generator is subjected is absolutely accurate.

 From equation (5), the output correction sensitivity

d ((14)

 1WVV

as well as from equation (2):

"FuP) cl (K-r))

It follows from the two previous equations that the compensation of accelerometric effects by the variable capacitance Cej is not purely linear due to nonlinearity depending on Ci in the denominator of equation (14). Thus, the law of general variation depends, on the one hand, on the law of frequency variation depending on the capacitance C of the variable capacitor 1 and, on the other hand, on the law of variation (4 capacitances C depending on acceleration.

As already mentioned, this last law depends essentially on the geometrical parameters, namely, the distance Z and the surface S of the reinforcement of the container C, which is derived from equation (8). From here, the change in capacity is derived:

dCj c 5- € oS (16)

Similarly to the first variant, for ease of manufacturing, only one parameter 2 or S is taken into account, whose change (non-linear) corrects the shape of the electrodes of capacitance Cj in order to accurately compensate for the linear variation of the frequency deviation of the resonator caused by acceleration.

According to the second embodiment shown in FIG. 5, the capacitance 0) varies depending on the surface S by means of a flexible plate 24, one end of which is rigidly fixed, while the other end is fixed longitudinally to one of the reinforcement 25 of the capacitor Cf capacitance. This movable reinforcement 25 of a rectangular parallelepiped shape has at a constant distance E, the projected part S of its surface opposite the other fixed reinforcement 26. The reinforcement 26 profile P (U) at each of its transverse edges, symmetrical with respect to the mean transverse plane of the moving reinforcement 25, the shape of which allows to compensate for the nonlinearity effect.

The fixed plate 26 is isolated from the movable plate 25 and the movable plate 25 is superimposed on the plate 24 by means of a fastening system, for example, similar to the system described in the first embodiment shown in FIG. 3 (elements 12,15,17 and 18).

FIG. Figure 6 shows the contour of the surface of the fixed plate 26 bounded by the transverse edges of the profiles P (i), symmetrical with respect to the axis Oi, perpendicular to shastin 24 and parallel to the vector K acceleration sensitivity, the direction of which is assumed to be known. In this case, denoting through the mass of the rolling reinforcement 25, performing the function of the load, and through the component of the acceleration vector r according to direction K, the basic dynamic equation for the relatively small movement of reinforcement 25 in the direction (or Oi) leads to the following equation:

.

(17)

where is the stiffness coefficient of the plate 24 (kg / s)

Claims (5)

From equations (14) and (17), it is now possible to derive the P (i) profile, which provides compensation for the effects of nonlinearity and defined by 1 ypi (j) du, where and U denote the thickness and coordinates of the midpoint of the movable plate 25. Substitute instead of this (17) to equation (15) and expressing (Ssch, through equation (16), get equation (14) in the following form gr (Iod5 КХ dU. (19 ilvvif-f The previous differential equation expressing function 5 depending on of changes in U, is written in the following form: (20) and B - constant, such as: ac x-EC Integrator equation (20), gender teaching A (iK) where K. is a constant of integration, found from the initial conditions at zero acceleration, i.e. depending on the surface So at the quiescent point Wo of the movable plate 25: and (2 ° AlSo-B) Profile P (and) in this case is derived from the derivative of the function S (and) obtained by equation (23): A1U-K12 From the previous equation (25), it appears that the nominal value of capacitance CJ is first corrected, such as: CCa.W 6oT and with acceleration the displacement dU of the mass M of the plate 25 will allow an increase in the accuracy of non-linear compensation According to other embodiments of the invention, the vector) t is not known. The calculation shows that compensation can be carried out using three variable capacitors of the mentioned type, connected in parallel between themselves and in series with the resonator, and arranged accordingly so that their moving plates would be parallel to the three main axes OX, OY, OZ piezocrystal 8 of the resonator 3. In FIG. 8, the arrangement of the reinforcement plates 13 and 14 of all three variable capacitors Cj, and Cr °, whose vertices are perpendicular to the three axes OX, OU and OZ, respectively, is represented schematically according to the aforementioned example of the first embodiment. FIG. 9, on the contrary, the surfaces of the plates 26 and 25 of all three variable capacitors C, Cj / i and Cj are arranged in parallel and at a corresponding constant distance S from the axes OX, OY and OZ, respectively, according to the aforementioned example of the second embodiment. In either of the previous cases, the capacitance of a capacitor is equal: as a non-limiting example in FIG. 7 shows the profile shape of a fixed plate 26 of a variable capacitor with a control capacitance C-j for the following values: t icr f; DO 5.10- F; Cr.20. .10 Hz, X 10 newton / m; M, 5. m; point of rest SQ (U ,, - К) 3 .. From the preceding equations (18) and (21) - (25) the conclusion is: (0) 0 0.884. F: A 1,768.10 m-4; , 82.10, 18a-1o l PWo-) table of the following values; 1.4. 4.6--10 (. Oo-X), M), M n,. 0 The invention formula. 1. An electric generator with a serial oscillation excitation circuit, containing a capacitance regulating the oscillation frequency, consisting of at least one variable capacitor, one of the plates of which is connected to the output of the circuit, a piezoelectric quartz pe3Ojiator, one of which is connected to another capacitor plate, and an amplifier, whose input is connected to another resonator terminal, and an output to an output of a series circuit, and a matching circuit for the level of the oscillation signal sent by said circuit, is connected its input with the output of the aforementioned circuit, of which it is, and with the fact that, in order to increase the stability of the frequency of electrical oscillations under the action of acceleration, it contains a device that is sensitive to the acceleration to which the generator is mechanically connected to a stationary and moving fittings of a variable capacitor according to the degree of freedom of movement. 2. The generator according to claim 1, characterized in that the acceleration sensitive device is an elastic return element of the movable reinforcement according to the degree of freedom of movement. 3. The generator according to claim 2, characterized in that said variable capacitor has an alternating distance between the plates, and the elastic return element consists of flexible plates that are fixed on aE) ature, installed in parallel and with the possibility of moving towards a fixed armature a variable capacitor. 4. Generator on PP. 2 and 3, that is, the direction of movement of the moving armature of the variable capacitor is parallel it is sensitive to the acceleration sensitivity vector of a piezoelectric resonator crystal. 5. The generator PP. 2 and 3, characterized in that said variable capacitance consists of three variable capacitors, each containing one device, sensitive to acceleration and to the elastic return of their moving armature, which are electrically connected in parallel with each other and in series with the resonator, and in the direction of movement of the moving the armatures of which are respectively parallel to the three main axes of the piezoelectric resonator crystal. Sources of information taken into account in the examination 1. Small-sized radio equipment Reference book of the radio amateur, Kiev, Naukova Dumka, 1976, p. 341-345. . Yergman L. Ultrasound and its use in science and technology. 1. Foreign literature, 1956, p. 98113. (Put.j (Reg. 2 17 14 (S) 19 If 17 I / v n yy p th (rig. 3 , / V.ut. g f R