RU2311568C2 - Electro-hydraulic control system - Google Patents

Abstract

FIELD: hydraulics, possible use for automatic control of movement of output elements of hydro-engines, possible use in regulators of volumetric and throttled hydro-engine with electric check connection in terms of superposition of element which regulates flow, for example, in controllable pumps or hydro-distributors, operating in self-oscillating mode.

SUBSTANCE: system contains serially connected first adder with first input, being the control effect input for system, amplifier, second adder, relay power amplifier, control mechanism, adjustable pump, hydro-engine, where output of relay power amplifier is connected through non-periodic filter to second input of second adder, and output of control mechanism is connected to second input of first adder through serially connected position sensor and correcting link.

EFFECT: reduced vibration, increased reliability of system operation.

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Description

The invention relates to automatic control devices, namely, electro-hydraulic control systems for the movement of the output elements of hydraulic motors depending on the parameters of the input control signal.

Electrohydraulic control systems (EGSU) are known, built on the basis of an adder, an electronic amplifier, an electromechanical converter, a source of hydraulic energy, a hydraulic booster, the output hydraulic lines of which are connected to an executive hydraulic motor - a hydraulic cylinder or a hydraulic motor, the output of which is connected through the feedback sensor to the input of the adder, which depending on the characteristics of the elements, they operate in a linear mode (see Gamynin N.S., Zhdanov Yu.K., Klimashin A.L. Dynamics of high-speed hydraulic control drive drive. - M .: "Mechanical Engineering", 1979. - 7 pp. [1]) or in the mode of pulse-width modulation (see Denisov LA, Nagorny BC Pneumatic and hydraulic automation devices. - M .: " Higher School ", 1978 - 195 p. [2]), where forced vibrations are formed in the EGSU with a multivibrator. Oscillation frequency and modulation depth - the amplitude of the oscillations of the input and output signals of the links are rigidly fixed by the parameters of the modulator - multivibrator. The choice of optimal oscillation parameters, with the goal of linearizing nonlinearities and increasing the speed of the EGSU, is limited by the design parameters of the linearizable links - an electromechanical converter, hydraulic booster, hydraulic actuator (see. Hydraulic servo drive. / Gamynin N.S., Kamenir Ya.A., Korobochkin B.L. . and others. - M .: "Engineering", 1968. - S.480-494 [3]). The disadvantage of such systems is their relatively low speed.

The closest to the claimed invention by its technical nature is the EGSU (see. Dynamics and accuracy of the operation of thermomechanical systems: Sat. Scientific Tr. / Tula Polytechnic Institute - Tula, 1980. - S.131-133 [4]), adopted for the prototype and shown in figure 1, which contains series-connected: the first adder 1 with the first input, which is the control input for the EGSU, the relay element as a special case is an amplifier with a high gain 2, the second adder 3, relay power amplifier 4, control mechanism Nia 5, steering pump 6, motor 7, wherein the relay output of the power amplifier 4 is connected through an aperiodic filter 8 to a second input of the second adder 3 and the output of the control mechanism 5 through 9 position (angle sensor) connected to the second input of the first adder 1.

By a corresponding choice of parameters of amplifier 2, relay power amplifier 4, and an aperiodic filter 8, the self-oscillating mode of the EGSU is formed with a self-oscillation frequency (25 ÷ 40) Hz at the output of the control mechanism 5, which provides an increase in speed in comparison with the EGSU [2], as well as linearization of friction and backlash in the elements.

A disadvantage of the known EGSU [4] is the limited ability to form optimal parameters of the switching frequency and amplitude of self-oscillations by a signal from the output of the control mechanism 5 to the input of an adjustable pump 6. The prototype implements a range of frequency of self-oscillations (25 ÷ 40) Hz and practically obtained, respectively, the oscillation amplitude is (9 ÷ 6)% of the maximum signal value from the output of the control mechanism 5, which determines the presence of vibration acting on the hydromechanical part of the EGSU and passing to its output.

The invention is aimed at reducing vibration and improving the reliability in operation of a high-speed EGSU operating in self-oscillating mode, the formation of optimal parameters of self-oscillations - increasing the frequency and decreasing the amplitude of oscillations by a signal from the output of the control mechanism to the input of an adjustable pump. The emergence of additional opportunities for the formation of optimal parameters of amplitude and frequency in the mode of self-oscillations allows you to expand the range of applications of serial and newly developed pumps in high-speed EGSU without their completion, which will reduce the cost of the developed EGSU.

This is achieved by the fact that in the EGSU containing the first adder in series with the first input, which is the control input for the EGSU, an amplifier, a second adder, a relay power amplifier, a control mechanism, an adjustable pump, a hydraulic motor, and the output of the relay power amplifier is connected through an aperiodic filter to the second input of the second adder, and the output of the control mechanism is connected to the position sensor, a correction link with the transfer function W is introduced:

where ξ is the attenuation parameter, should be in the range of 0.7 ÷ 0.9;

T ₁ , T ₂ - time constants, s;

p is the differentiation operator;

T ₁ = (0.75 ÷ 0.8) ¹ / ω,

where ω is the value of the angular frequency of the signal at the first input of the first adder, at which the phase delay of the signal at the output of the position sensor 9 is 180 ° for the correction link with the value of the transfer function W = 1.1 / s;

T ₂ = (0.71 ÷ 0.77) T ₁ ,

moreover, the input of the correction link is connected to the output of the position sensor, and the output is connected to the second input of the first adder.

The invention is confirmed by drawings. Figure 1 shows the functional diagram of the prototype, figure 2 is a functional diagram of the EGSU, figure 3 is a variant of the corrective link with the transfer function (1) for the DC signal from the output of the position sensor 9 to the input of the corrective link.

Information confirming the possibility of carrying out the invention with the above result is as follows.

EGSU (figure 2) contains serially connected: the first adder 1 with the first input, which is the input of the control action of the EGSU, amplifier 2, the second adder 3, relay power amplifier 4, control mechanism 5, adjustable pump 6, hydraulic motor 7, and the output of the relay amplifier power 4 is connected through an aperiodic filter 8 to the second input of the second adder 3, and the output of the control mechanism 5 through the position sensor 9 is connected to the input of the correction link 10 having the transfer function (1) with the parameter value: parameter damping ξ within (0.7 ÷ 0.9), time constant T ₁ = (0.75 ÷ 0.8) ¹ / ω, where ω is the value of the angular frequency of the signal at the first input of the first adder, at which the phase delay of the signal at the output of the position sensor 9 is 180 ° for the correction link with the value of the transfer function W = 1, the time constant T ₂ = (0.71 ÷ 0.77) T ₁ , and the output of the correction link 10 is connected to the second input of the first adder 1.

The work of the EGSU is as follows.

In a closed internal circuit of the EGSU formed by the adder 3, a power relay 4 with current feedback through an aperiodic filter 8, self-oscillations of a relatively high frequency from 300 to 600 Hz are formed, which increase the speed of the electromagnetic converter of the control mechanism 5.

In the external circuit of the electronic control system, in addition to the internal circuit, the first adder 1, amplifier 2, control mechanism 5 with feedback on the position of the regulatory body of the adjustable pump 6 from the output of the control mechanism 5 through the position sensor 9 and the corrective link 10 to the second input of the adder 1, are formed self-oscillations with a frequency of up to 70 Hz and amplitude (2 ÷ 4)% of the maximum value of the output signal value from the output of the control mechanism 5. The indicated parameters of self-oscillations are achieved by adjusting the gain Itel 2, the transmission coefficient of the position sensor 9 and the choice of the parameters of the correction link declared by the transfer function (1) 10. The correction link (Fig. 3) is made on the operational amplifier 11. The implementation of the transfer function of the correction link W is determined by the ratio of the transmission resistance in the feedback circuit of the resistor 12 with the resistance value R _OC to the transmission resistance of the input circuit with the resistance value determined by the configuration of the RC chain of capacitors 13, 14 with the capacitance C1 and C2, resistors 15, 16 with resistance value R1 and R2 (see Semiconductor integrated circuits. Series 140 (1UT402). Guidelines for the use of RD11.bKO.342.007-72 C.248-255 [5]). The values of the attenuation parameter ξ and the time constants T ₁ , T _{2 of the} transfer function (1) of the correction link are provided by the choice of the nominal values of the parameters of the elements C1, C2, R1, R2, R _OC , satisfying the relations [5]:

where W is the transfer function of the corrective link 10;

K (p) is the value of the transfer function of the corrective link 10;

p is the differentiation operator;

Z _O (p) is the transmission resistance in the feedback circuit with a resistor value of 12 R _OC , Ohm;

Z ₁ (p) is the transmission resistance of the input circuit, determined by the ratio:

where R1, R2 is the resistance value of the resistors 15 and 16, the ratio of which must satisfy the conditions R1 = R2, R1 + R2 = R _OC , Ohm;

T ₁ , T ₂ , T ₃ - time constants, s;

ξ is the attenuation parameter,

where ω is the value of the angular frequency of the signal at the first input of the first adder, at which the phase delay of the signal at the output of the position sensor is 180 ° for the correction link 10 with the value of the transfer function W = 1.1 / s;

C1 and C2 - the value of the capacitance of the capacitors 13 and 14, F;

T ₂ = (0.71 ÷ 0.77) T ₁ = 0.5R1 · C1;

T ₃ = 2ξT _1:

The minus sign of the function K (p) is taken into account when generating a negative feedback signal from the position sensor 9, and the resistance value of the resistor 17: R = R _OC (R1 + R2) / (R _OC + R1 + R2).

A decrease in the amplitude and an increase in the frequency of self-oscillations at the output of the control mechanism 5 (Fig. 2) when working with the corrective link 10 significantly reduces the vibration in the EGSU, increases the reliability of its operation, in addition, provides speed and linearization of the nonlinearities of the control mechanism 5, an adjustable pump 6, a hydraulic motor 7, namely, backlash, friction, dead zone, hysteresis, while achieving a higher bandwidth of the entire EGSU operating in a pulse-width self-oscillating mode.

Thus, in the claimed EGSU, a decrease (1.3 ÷ 2) times of the amplitude of self-oscillations by a signal from the output of the control mechanism 5 and a corresponding increase in the frequency of self-oscillations in the control loop of the EGSU, thereby significantly reducing vibration, while ensuring speed, linearity of characteristics , loads on EGSU elements are reduced, there is an opportunity to expand the range of applications of serial and newly developed adjustable hydraulic pumps, hydraulic control valves with their adaptation to a self-propelled truck operational mode in high-precision high-speed drives.

The claimed technical solution has been tested in the structure of the EGSU with control of the supply of a serial axial piston displacement pump N32RDM, an experimental axial plunger pump АУИЖ.063234.026, which has higher leaks, but at the same time, is more technologically advanced and easy to maintain. In this case, the parameters of amplitude self-oscillations were obtained at the output of the control mechanism (2 ÷ 4)% of the maximum rotation of the pump control element with a frequency of (50 ÷ 70) Hz with a decrease in vibration affecting the hydromechanical part of the EGSU.

The claimed technical solution ensured the restoration of the performance of the previously manufactured EGSU during the period of operation at the facility by introducing the corrective link with the transfer function (1).

LITERATURE

1 Gamynin B.C., Zhdanov Yu.K., Klimashin A.L. The dynamics of a high-speed hydraulic drive. - M .: "Engineering", 1979. - 7 p.

2 Denisov A.A., Nagorny B.C. Pneumatic and hydraulic automation devices. - M.: "Higher School", 1978. - 195 p.

3 Hydraulic servo drive. / Gamynin N.S., Kamenir Y.A., Korobochkin B.L. and others. - M.: "Mechanical Engineering", 1968. - S. 480-494.

4 Dynamics and accuracy of the operation of thermomechanical systems: Sat. scientific tr / Tula Polytechnic Institute. - Tula, 1980 .-- S.131-133.

5 Integrated semiconductor microcircuits. Series 140 (1UT402). Application Guide RD11.bKO.342.007-72 - S.248-255.

Claims (1)

An electro-hydraulic control system comprising a first adder connected in series with a first input, which is a control input for an electro-hydraulic control system, an amplifier, a second adder, a relay power amplifier, a control mechanism, an adjustable pump, a hydraulic motor, the output of the relay power amplifier being connected via an aperiodic filter to the second the input of the second adder, and the output of the control mechanism is connected to the input of the position sensor, characterized in that it is introduced orrektiruyuschee unit with transfer function W

where ξ - attenuation parameter should be in the range of 0.7 ÷ 0.9; T ₁ , T ₂ - time constants, s; p is the differentiation operator; T ₁ = (0.75 ÷ 0.8) ¹ / ω, where ω is the value of the angular frequency of the signal at the first input of the first adder, at which the phase delay of the signal at the output of the position sensor is 180 ° for the correction link with the value of the transfer function W = 1.1 / s; T ₂ = (0.71 ÷ 0.77) T ₁ , moreover, the input of the correction link is connected to the output of the position sensor, and the output is connected to the second input of the first adder.

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