RU2489607C1 - Two-stage electrohydraulic amplifier with electric flow feedback - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: amplifier is intended for automatic systems. The amplifier includes a summing operating amplifier with two inputs, an electronic power amplifier, an electromechanical converter, a hydraulic control valve of the first stage; a hydraulic control valve of the second stage, which is kinematically connected to a movable element of an electric feedback sensor hydraulically connected to supply and drain hydraulic lines, hydraulically connected through two hydraulic lines to the hydraulic control valve of the first stage and having two output hydraulic lines to be connected to a consumer; matching equipment, the input of which is connected to a signal winding of the electric feedback sensor of the hydraulic control valve of the second stage; an electrohydraulic pressure drop sensor hydraulically connected through two hydraulic lines to output hydraulic lines of the hydraulic control valve of the second stage; an electronic calculating device, one input of which is connected to the output of the matching equipment of the electric feedback sensor of hydraulic control valve of the second stage, and the other input is connected to an electric output of the electrohydraulic pressure drop sensor; output of the electronic calculating device is connected to the second input of the summing operating amplifier.

EFFECT: increasing the efficiency of power part of the drive.

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Description

The invention relates to the field of mechanical engineering, namely to electro-hydraulic automatic systems, widely used in various branches of technology, where high-speed electro-hydraulic amplifiers are used. These are test benches in the automotive and aviation industries, and powerful vibroinstallations in modern oil and gas search systems, and rolling mills in metallurgy and a number of other applications.

Known two-stage electro-hydraulic amplifiers of the American company MOOG D765 series [catalog "Servo valves of the company MOOG Gmbh. Nizhny Novgorod branch, Russia, 2003 ”].

The specified two-stage electro-hydraulic amplifier, which is by far the most advanced, will be taken as a prototype.

The principal electro-hydraulic circuit of the electro-hydraulic amplifier of the prototype is shown in figure 1 and contains:

- summing operational amplifier (1) with two inputs, one of which is supplied with a control signal (Uвx);

- an electronic power amplifier (2), the input of which is connected to the output of the summing operational amplifier (1);

- an electromechanical converter (3), the control winding of which is connected to the output of the electronic power amplifier (2), and the armature is kinematically connected to the movable element of the hydrodistributor of the first stage (4);

- the hydrodistributor of the first cascade (4), hydraulically connected to the discharge and discharge hydraulic lines;

- a hydrodistributor of the second cascade (7) kinematically connected to the movable element of the electric feedback sensor (6), hydraulically connected to the discharge and discharge hydraulic lines, two hydraulic lines, hydraulically connected to the hydrodistributor of the first stage (4) and having two output hydraulic lines for connection to the consumer ;

- matching equipment (5), the input of which is connected to the signal winding of the electric feedback sensor (6) of the hydraulic valve of the second stage (7), and the output of matching equipment is connected to the second input of the summing operational amplifier (1).

The disadvantage of the considered electro-hydraulic amplifier prototype is the dependence of the distribution of hydraulic fluid flow of the working fluid on the differential pressure from the load in the actuating device of the tracking drive, which includes a hydraulic booster, which reduces the efficiency of this drive.

The task of the invention is to remedy this drawback.

The problem is solved in that the two-stage electro-hydraulic amplifier contains:

- a summing operational amplifier with two inputs, one of which is supplied with a control signal;

- an electronic power amplifier, the input of which is connected to the output of the summing operational amplifier;

- an electromechanical converter, the control winding of which is connected to the output of the electronic power amplifier, and the armature is kinematically connected to the movable element of the hydrodistributor of the first stage;

- a hydrodistributor of the first stage, hydraulically connected to the discharge and discharge hydraulic lines;

- a hydrodistributor of the second stage kinematically connected with a movable element of the electric feedback sensor, hydraulically connected to the discharge and discharge hydraulic lines, two hydraulic lines, hydraulically connected to the hydraulic distributor of the first stage and having two output hydraulic lines for connection to the consumer;

- matching equipment, the input of which is connected to the signal winding of the electrical feedback sensor of the hydrodistributor of the second stage,

while new is that, according to the invention, in the circuit diagram of the claimed electro-hydraulic amplifier includes:

- electro-hydraulic differential pressure sensor, hydraulically connected by two hydraulic lines to the output hydraulic lines of the valve of the second stage;

- an electronic computing device, one input of which is connected to the output of the matching equipment of the electric feedback valve of the hydrodistributor of the second stage, and the other input is connected to the electrical output of the electro-hydraulic differential pressure sensor, the output of the electronic computing device is connected to the second input of the summing operational amplifier.

The essence of the claimed invention is illustrated in the drawing (figure 2), which shows a schematic electro-hydraulic circuit of an advanced electro-hydraulic amplifier, which contains:

- a summing operational amplifier (1) with two inputs, one of which is supplied with a control signal (U _in );

- an electronic power amplifier (2), the input of which is connected to the output of the second summing operational amplifier (1);

- an electromechanical converter (3), the control winding of which is connected to the output of the electronic power amplifier (2), and the armature is kinematically connected to the movable element of the hydrodistributor of the first stage (4);

- the hydrodistributor of the first cascade (4), hydraulically connected to the discharge and discharge hydraulic lines;

- a hydrodistributor of the second cascade (7) kinematically connected to the movable element of the electric feedback sensor (6), hydraulically connected to the discharge and discharge hydraulic lines, hydraulically connected to the hydrodistributor of the first stage (4) by two hydraulic lines and having two output hydraulic lines for connection with the consumer;

- matching equipment (5), the input of which is connected to the signal winding of the electric feedback sensor (6) of the hydrodistributor of the second stage (7);

- electro-hydraulic differential pressure sensor (8), hydraulically connected by two hydraulic lines to the output hydraulic lines of the valve of the second stage (7);

- electronic computing device (9), one input of which is connected to the output (U ₁ ) of matching equipment (5) of the electric feedback sensor (6) of the hydraulic valve of the second stage (7), and the other input is connected to the electrical output (U ₂ ) of the electro-hydraulic sensor differential pressure (8), the output (U _OC ) of the electronic computing device (9) is connected to the second input of the summing operational amplifier (1).

The claimed two-stage electro-hydraulic amplifier operates as follows (see figure 2).

The input of the summing operational amplifier (1) receives the input control signal (U _I ). The output of the summing operational amplifier is connected to the input of an electronic power amplifier (2), designed to amplify the electrical signal fed to the control winding of the electromechanical converter (3), the armature of which is kinematically connected to the moving element of the hydraulic control valve of the first stage (4), connected by two hydraulic lines to the discharge hydraulic lines and discharge and through two hydraulic lines of the control valve of the second cascade (7), kinematically connected with the movable element of the electric feedback sensor (6), an electrical signal (U ₁ ) from the signal winding of this sensor, through matching equipment (5), is fed to the first input of an electronic computing device (9). The second input of the electronic computing device (9) is connected to the electrical output (U ₂ ) of the differential pressure sensor (8), which measures the pressure difference in the output hydraulic lines of the declared hydraulic booster.

The electronic computing device calculates the flow rate feedback signal (U _OC ) supplied to the second input of the summing operational amplifier, corresponding to the module and sign of the working fluid flow Q distributed by the declared hydraulic booster.

To clarify the principle of operation of the improved hydraulic booster, consider the matching coefficient K _c :

$$K_C=\frac{U_{\mathrm{ABOUT}\mathrm{FROM}}^m}{Q_0};$$

Where:

- максимальное значение сигнала обратной связи на выходе электронного вычислительного устройства; $$U_{OC}^m$$

- the maximum value of the feedback signal at the output of the electronic computing device;

$$Q_0=\mu b_u{x}_0\sqrt{\frac{g}{\gamma }\Delta P_o},$$

Q ₀ is the flow rate of the working fluid at x ₀ and ΔP _n = 0;

x ₀ - a maximum coordinate value determining the magnitude and sign of the shift control valve spool of the output stage from the neutral position at the maximum control signal (U _Bx) and at ΔP _n = 0.

ΔP ₀ = P _n -P _l

Where:

P _n - pressure in the discharge line;

P _l - pressure in the discharge line;

ΔP _n = P ₁ -P ₂ .

Where:

P ₁ and P ₂ - pressure in the output hydraulic lines of the hydraulic booster;

µ is the flow coefficient of the working windows of the valve;

b _u - the width of the working windows of the valve;

g is the acceleration of gravity;

γ is the specific gravity of the working fluid.

Current Flow Rate (Q):

$$Q=\mu b_u{x}_s\sqrt{\frac{g}{\gamma }\Delta P_0(\mathrm{one}-\frac{\Delta P_n}{\Delta P_o}Sgn{x}_s)},$$

where x _z - the current value of the coordinate of the valve of the control valve of the output stage.

Consider the expression:

$${\mathrm{TO}}_{\mathrm{FROM}}Q=\frac{U_{OC}^m}{Q_o}Q=U_{OC}^m\frac{x_s}{x_0}\sqrt{\mathrm{one}-\frac{\Delta P_n}{\Delta P_0}Sgn{x}_s}.$$

(с учетом того, что $$U_{OC}^m$$

соответствует x₀) и $$\frac{\Delta P_n}{\Delta P_0}=\frac{U_2}{U_2^0}$$

то формула для определения сигнала обратной связи U_OC примет вид:Given that $$\frac{x_s}{x_0}=\frac{U_{\mathrm{one}}}{U_{OC}^m}$$

(given that $$U_{OC}^m$$

corresponds to x ₀ ) and $$\frac{\Delta P_n}{\Delta P_0}=\frac{U_2}{{\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="00000012.png"\; state="\{\{state\}\}">U</figure-callout>}}_2^0}$$

then the formula for determining the feedback signal U _OC will take the form:

Where:

$$U_{OC}=U_{\mathrm{one}}\sqrt{\mathrm{one}-\frac{U_2}{{\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="00000012.png"\; state="\{\{state\}\}">U</figure-callout>}}_2^0}Sgn{U}_{\mathrm{one}}}$$

U ₁ - an electrical signal at the output of the matching equipment of the feedback sensor of the hydrodistributor of the second stage;

U ₂ is an electrical signal corresponding to ΔP _n ;

- электрический сигнал, соответствующий ΔP₀. $${\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="00000012.png"\; state="\{\{state\}\}">U</figure-callout>}}_2^0$$

is an electrical signal corresponding to ΔP ₀ .

On closing the circuit, which inlet U _Rin, and the output is x _h and subsequent substitution x _of a formula for determining the hydraulic fluid flow dispensed booster, being independent of said rate of change within the prescribed limits, the pressure differential between the output hydraulic lines of the hydraulic booster .

As a result, we have:

The invariance of the speed characteristics to the change in pressure drop from the load of the throttle control hydraulic drive controlled by the claimed hydraulic booster.

The increase in the coefficient of performance (COP) of the power part of the above hydraulic drive.

The ability, if necessary, to implement the speed limit of the output link of the actuator by limiting the input signal (U _I ).

Claims (1)

A two-stage electro-hydraulic amplifier with electric flow feedback, containing:
- a summing operational amplifier with two inputs, one of which is supplied with a control signal;
- an electronic power amplifier, the input of which is connected to the output of the summing operational amplifier;
- an electromechanical converter, the control winding of which is connected to the output of the electronic power amplifier, and the armature is kinematically connected with the movable element of the hydrodistributor of the first stage;
- a hydrodistributor of the first stage, hydraulically connected to the discharge and discharge hydraulic lines;
- a hydrodistributor of the second cascade kinematically connected to the movable element of the electric feedback sensor, hydraulically connected to the discharge and discharge hydraulic lines, hydraulically coupled to the hydrodistributor of the first cascade with two hydraulic lines and having two output hydraulic lines for connection with the consumer;
- matching equipment, the input of which is connected to the signal winding of the electrical feedback sensor of the hydrodistributor of the second stage,
characterized in that the circuit diagram of the claimed electro-hydraulic amplifier includes:
- electro-hydraulic differential pressure sensor, hydraulically connected by two hydraulic lines to the output hydraulic lines of the valve of the second stage;
- an electronic computing device, one input of which is connected to the output of the matching equipment of the electric feedback sensor of the hydraulic valve of the second stage, and the other input is connected to the electrical output of the electro-hydraulic differential pressure sensor; the output of the electronic computing device is connected to the second input of the summing operational amplifier.

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