阅读说明：本技术 一种双阀并联控制液压缸的电液力控制系统 (Electric hydraulic control system of double-valve parallel control hydraulic cylinder ) 是由 李建英 谢寅凯 谢帅 张建军 于 2019-10-16 设计创作，主要内容包括：本发明提供了一种双阀并联控制液压缸的电液力控制系统。其包括液压缸、电液比例调速器、电液伺服阀、控制器、负载、活塞杆、力传感器。其中,电液比例调速阀与电液伺服阀为并联连接,由控制器控制。当压力传感器检测活塞杆压力后,将反馈信号传输给控制器,控制器调节两阀输入信号,进而达到控制液压缸的目的。本发明提供的一种双阀并联控制液压缸的电液力控制系统能够很好的提高电液力控制系统的快速性及稳定性,并且还可以提高电液力控制系统的频率响应以及消除多余力,降低成本等。(The invention provides an electric hydraulic control system of a double-valve parallel control hydraulic cylinder. The electro-hydraulic proportional speed regulator comprises a hydraulic cylinder, an electro-hydraulic proportional speed regulator, an electro-hydraulic servo valve, a controller, a load, a piston rod and a force sensor. The electro-hydraulic proportional speed regulating valve and the electro-hydraulic servo valve are connected in parallel and controlled by the controller. When the pressure sensor detects the pressure of the piston rod, the feedback signal is transmitted to the controller, and the controller adjusts input signals of the two valves, so that the aim of controlling the hydraulic cylinder is fulfilled. The electric hydraulic control system of the double-valve parallel control hydraulic cylinder provided by the invention can well improve the rapidity and the stability of the electric hydraulic control system, and can also improve the frequency response of the electric hydraulic control system, eliminate redundant force, reduce the cost and the like.)

1. The invention discloses an electric hydraulic control system of a double-valve parallel control hydraulic cylinder, which is characterized by comprising the following components: the hydraulic system comprises a hydraulic cylinder (1), a piston rod (2), an electro-hydraulic proportional regulator (3), an electro-hydraulic servo valve (4), a pressure sensor (5), a controller (6), an oil tank (7), a pressure gauge (8), an overflow valve (9), an oil pump (10) and a load (11).

2. The electric hydraulic control system of the double-valve parallel control hydraulic cylinder as claimed in claim 1, wherein: the piston rod (2) is positioned in the hydraulic cylinder (1); the pressure sensor (5) is positioned at the tail end of the piston rod (2); the load (11) is located behind the pressure sensor (5); when the pressure sensor (5) detects the pressure of the piston rod (2), a feedback signal is transmitted to the controller (6), and the controller (6) further controls input signals of the electro-hydraulic proportional regulating valve (3) and the electro-hydraulic servo valve (4); the electro-hydraulic proportional regulating valve (3) is connected with the electro-hydraulic servo valve (4) in parallel; the output hydraulic oil of the electro-hydraulic proportional control valve (3) and the output hydraulic oil of the electro-hydraulic servo valve (4) are combined into the same pipeline and used as the hydraulic oil input end of the hydraulic cylinder (1); an oil pipe is connected into an oil tank (7) by an oil pumping end of an oil pump (10), and hydraulic oil in the oil tank (7) is pumped into an electro-hydraulic proportional regulating valve (3) and an electro-hydraulic servo valve (4) which are connected in parallel as input hydraulic oil.

3. The electric hydraulic control system of a double-valve parallel control hydraulic cylinder according to claim 1 and claim 2 is characterized by the following formula:

the formula I is as follows: u shape_e＝U_r-U_f

The formula II is as follows: u shape_f＝K_fFF_g

The formula III is as follows: Δ i ═ K_aU_e

The formula four is as follows: x_v＝ΔiK_svG_sv(s)

The formula five is as follows: q₁＝K_qX_v-K_cp_L

Formula six:

the formula seven:

the formula eight:

the formula is nine:

wherein, in the formula I, U_eIs a deviation voltage signal, U_fFor feedback of voltage signals, U_eIs an input voltage signal; in the second formula, K_fFIs a pressure sensorGain, F_gOutputting force for the hydraulic cylinder detected by the pressure sensor; in the third formula, Δ i is the output current of the servo amplifier of the electro-hydraulic servo valve, K_aGain of an electrohydraulic servo valve amplifier; in the formula IV, X_vThe displacement of the valve core of the electro-hydraulic servo valve of the electro-hydraulic force control system shown in FIG. 2, K_svIs an electro-hydraulic servo valve gain, G_sv(s) is K_svAn electro-hydraulic servo valve transfer function equal to 1; in the fifth formula, Q₁Is the output flow of the electro-hydraulic servo valve, K_qFor the flow gain of the electro-hydraulic servo valve, K_cFlow-pressure coefficient, p, of electrohydraulic servo valve_LIs the load pressure; in the sixth formula, Q_LIs the total input flow, Q, of the cylinder₂Is the output flow of the electro-hydraulic proportional speed regulating valve, A_pIs the effective area of the piston of the hydraulic cylinder, s is Laplace operator, X_pIs the piston displacement of the hydraulic cylinder, C_tpIs the internal leakage coefficient, V, of the hydraulic cylinder_tIs the effective volume of the hydraulic cylinder, and beta e is the effective volume elastic modulus of the hydraulic cylinder; in the formula seven, the first step is carried out,

Technical Field

The invention mainly relates to material testing machines, structural object fatigue testing machines, wheel braking devices and the like, and mainly relates to an electric hydraulic control system of a double-valve parallel control hydraulic cylinder.

Background

Electro-hydraulic servo control systems are also important in practical production,

with the continuous development and updating of scientific technology, a higher standard is provided for some electro-hydraulic servo control systems in engineering practice, and for a well-known main power control system, the system is required to have higher accuracy, rapidity and stability, and because an electro-hydraulic servo valve has a certain problem of low frequency response, redundant force is often generated in the force loading process, and the redundant force existing in the system is further required to be eliminated.

Disclosure of Invention

The invention provides an electro-hydraulic control system of a double-valve parallel control hydraulic cylinder, which can well improve the rapidity and the stability of the electro-hydraulic control system, improve the frequency response of the electro-hydraulic control system, eliminate redundant force, reduce the cost and the like by controlling the hydraulic cylinder in a mode of connecting an electro-hydraulic servo valve and an electro-hydraulic proportional speed regulating valve in parallel.

The invention provides an electric hydraulic control system of a double-valve parallel control hydraulic cylinder, which is characterized by comprising the following components: the hydraulic system comprises a hydraulic cylinder (1), a piston rod (2), an electro-hydraulic proportional regulator (3), an electro-hydraulic servo valve (4), a pressure sensor (5), a controller (6), an oil tank (7), a pressure gauge (8), an overflow valve (9), an oil pump (10) and a load (11).

Wherein the piston rod (2) is positioned in the hydraulic cylinder (1); the pressure sensor (5) is positioned at the tail end of the piston rod (2); the load (11) is located behind the pressure sensor (5); when the pressure sensor (5) detects the pressure of the piston rod (2), a feedback signal is transmitted to the controller (6), and the controller (6) further controls input signals of the electro-hydraulic proportional regulating valve (3) and the electro-hydraulic servo valve (4); the electro-hydraulic proportional regulating valve (3) is connected with the electro-hydraulic servo valve (4) in parallel; the output hydraulic oil of the electro-hydraulic proportional control valve (3) and the output hydraulic oil of the electro-hydraulic servo valve (4) are combined into the same pipeline and used as the hydraulic oil input end of the hydraulic cylinder (1); an oil pipe is connected into an oil tank (7) by an oil pumping end of an oil pump (10), and hydraulic oil in the oil tank (7) is pumped into an electro-hydraulic proportional regulating valve (3) and an electro-hydraulic servo valve (4) which are connected in parallel as input hydraulic oil.

Drawings

In the drawings:

fig. 1 is a schematic diagram of the basic composition of an electro-hydraulic force control system having only an electro-hydraulic servo valve.

FIG. 2 is a schematic diagram of the structure of an electric hydraulic control system of a double-valve parallel control hydraulic cylinder.

FIG. 3 is a schematic diagram of the logic algorithm of the electric hydraulic control system of the double-valve parallel control hydraulic cylinder.

All the same elements and loads of the different systems shown in fig. 1 and 2 have the same parameters and specifications.

Detailed Description

The present invention provides an electro-hydraulic control system for a double-valve parallel control hydraulic cylinder, which is explained in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the basic components of an electro-hydraulic force control system with only electro-hydraulic servo valves, which includes: the hydraulic system comprises a hydraulic cylinder (1), a piston rod (2), a load (3), an electro-hydraulic servo valve (4), a pressure sensor (5), a controller (6), an oil tank (7), a pressure gauge (8), an overflow valve (9) and an oil pump (10). Wherein the piston rod (2) is positioned in the hydraulic cylinder (1); the pressure sensor (5) is positioned at the tail end of the piston rod (2); the load (3) is located behind the pressure sensor (5); when the pressure sensor (5) detects the pressure of the piston rod (2), a feedback signal is transmitted to the controller (6), and the controller (6) further controls an input signal of the electro-hydraulic servo valve (4); the output hydraulic oil of the electro-hydraulic servo valve (4) is used as the hydraulic oil input end of the hydraulic cylinder (1); the oil pumping end of the oil pump (10) connects an oil pipe into an oil tank (7), and the hydraulic oil in the oil tank (7) is pumped into the electro-hydraulic servo valve (4) as input hydraulic oil.

Referring to fig. 2 and fig. 3, an electro-hydraulic control system for a double-valve parallel control hydraulic cylinder according to the present invention is described, which mainly includes: the hydraulic system comprises a hydraulic cylinder (1), a piston rod (2), an electro-hydraulic proportional regulator (3), an electro-hydraulic servo valve (4), a pressure sensor (5), a controller (6), an oil tank (7), a pressure gauge (8), an overflow valve (9), an oil pump (10) and a load (11).

Wherein the piston rod (2) is positioned in the hydraulic cylinder (1); the pressure sensor (5) is positioned at the tail end of the piston rod (2); the load (11) is located behind the pressure sensor (5); when the pressure sensor (5) detects the pressure of the piston rod (2), a feedback signal is transmitted to the controller (6), and the controller (6) further controls input signals of the electro-hydraulic proportional regulating valve (3) and the electro-hydraulic servo valve (4); the electro-hydraulic proportional regulating valve (3) is connected with the electro-hydraulic servo valve (4) in parallel; the output hydraulic oil of the electro-hydraulic proportional control valve (3) and the output hydraulic oil of the electro-hydraulic servo valve (4) are combined into the same pipeline and used as the hydraulic oil input end of the hydraulic cylinder (1); an oil pipe is connected into an oil tank (7) by an oil pumping end of an oil pump (10), and hydraulic oil in the oil tank (7) is pumped into an electro-hydraulic proportional regulating valve (3) and an electro-hydraulic servo valve (4) which are connected in parallel as input hydraulic oil.

After the system is started, an oil pump (10) extracts hydraulic oil from an oil tank (7), the hydraulic oil respectively enters an electro-hydraulic proportional regulator (3) and an electro-hydraulic servo valve (4) which are connected in parallel, the hydraulic oil output from the electro-hydraulic proportional regulator (3) and the electro-hydraulic servo valve (4) is used as an oil supply end of a hydraulic cylinder (1) to supply oil to the hydraulic cylinder (1), the hydraulic oil enters the hydraulic cylinder to push a piston rod (2) to load force, a pressure sensor (5) at the front end of the piston rod (2) converts pressure into a voltage signal and transmits the voltage signal to a controller (6), the electro-hydraulic proportional speed regulating valve (3) can be closed by the controller when the difference between the feedback voltage of the pressure sensor and the system input voltage is small, the electro-hydraulic servo speed regulating valve (3) is not supplied with oil any more, the system pressure error is compensated by the controller (6) performing feedback regulation on the electro-hydraulic servo valve (4) (the small error is regulated by the electro-hydraulic servo, the system completes the work.

The electro-hydraulic control system of the invention enables the displacement of the electro-hydraulic servo valve core to be smaller than the valve core displacement of the electro-hydraulic servo valve of the system only with the electro-hydraulic servo valve due to the addition of the electro-hydraulic proportional speed regulating valve, the speed of the system from the beginning to the position of the appointed valve core is improved, and the displacement of the valve core of the electro-hydraulic servo valve needing feedback regulation is also very small, so that the feedback regulation can be realized more quickly, and the purpose of improving the rapidity of the system is achieved.

The parallel connection of the electro-hydraulic proportional speed regulating valve and the electro-hydraulic servo valve needs to be correspondingly specially explained as follows:

fig. 1 is a schematic diagram showing the composition of an electro-hydraulic control system having only an electro-hydraulic servo valve, and fig. 2 is different from fig. 1 in that the present invention is a parallel connection structure of an electro-hydraulic proportional speed control valve and an electro-hydraulic servo valve.

The parallel connection of the electro-hydraulic proportional speed control valve and the electro-hydraulic servo valve in fig. 2 is a combination for combining the advantages of both valves.

The electro-hydraulic proportional speed regulating valve has the advantages of short starting time, convenience in operation, low cost and the like, so that the problem of low frequency of part of electro-hydraulic servo valves can be solved, the quick starting of a system is realized, and redundant force is eliminated.

And the electro-hydraulic proportional speed regulating valve is connected with the electro-hydraulic servo valve in parallel, so that the pressure of the electro-hydraulic servo valve can be well relieved, and the rapidity of the system can be well improved by the way of supplying oil to the hydraulic cylinder through the parallel connection of the two valves. The electro-hydraulic servo valve has high control precision, is connected in parallel with the electro-hydraulic proportional speed regulating valve to commonly act on the hydraulic cylinder for oil inlet, and can well supplement each other.

Because the electro-hydraulic control system is adopted, the load pressure is gradually increased from zero in the force loading process, and for the system, the electro-hydraulic proportional speed regulating valve is adopted, so that the speed stability of the system can be improved to a certain extent. In the system, the pressure difference of the hydraulic oil passing through the front end and the rear end of the throttle valve in the electro-hydraulic proportional speed regulating valve is a constant value, so that the influence of the system along with the change of the load is reduced, the flow passing through the electro-hydraulic proportional speed regulating valve does not change along with the pressure difference, and the stability of the system can be improved for the electro-hydraulic control system of the hydraulic cylinder controlled by the electro-hydraulic proportional speed regulating valve and the servo valve in parallel.

As shown in fig. 3, since the parallel connection of the electro-hydraulic proportional speed control valve and the electro-hydraulic servo valve is adopted to perform the oil feeding on the hydraulic cylinder together, so that the load pressure has the same effect on the two valves, when the flow equation derivation of the electro-hydraulic servo valve is performed, the flow equation derivation of the electro-hydraulic servo valve is the same as that of the electro-hydraulic control system (fig. 1) only having the electro-hydraulic servo valve, the influence on parameters is avoided, the whole system is not complicated, and the invention is also a great outstanding point.

The controller controls the flow and the switch of the electro-hydraulic proportional speed regulating valve through a feedback signal, and the electro-hydraulic proportional speed regulating valve is closed after reaching the specified load pressure and is subjected to feedback compensation by the electro-hydraulic servo valve.

The electro-hydraulic control system of the double-valve parallel control hydraulic cylinder provided by the invention relates to the following formula:

the formula I is as follows: u shape_e＝U_r-U_f

The formula II is as follows: u shape_f＝K_fFF_g

The formula III is as follows: Δ i ═ K_aU_e

The formula four is as follows: x_v＝ΔiK_svG_sv(s)

The formula five is as follows: q₁＝K_qX_v-K_cp_L

Formula six:

the formula seven:

the formula eight:

the formula is nine, and the formula is,

wherein, in the formula I, U_eIs a deviation voltage signal, U_fFor feedback of voltage signals, U_eIs an input voltage signal; in the second formula, K_fFFor pressure sensor gain, F_gOutputting force for the hydraulic cylinder detected by the pressure sensor; in the third formula, Δ i is the output current of the servo amplifier of the electro-hydraulic servo valve, K_aGain of an electrohydraulic servo valve amplifier; in the formula IV, X_vThe displacement of the valve core of the electro-hydraulic servo valve of the electro-hydraulic force control system shown in FIG. 2, K_svFor electro-hydraulic servo valve gain，G_sv(s) is K_svAn electro-hydraulic servo valve transfer function equal to 1; in the fifth formula, Q₁Is the output flow of the electro-hydraulic servo valve, K_qFor the flow gain of the electro-hydraulic servo valve, K_cFlow-pressure coefficient, p, of electrohydraulic servo valve_LIs the load pressure; in the sixth formula, Q_LIs the total input flow, Q, of the cylinder₂Is the output flow of the electro-hydraulic proportional speed regulating valve, A_pIs the effective area of the piston of the hydraulic cylinder, s is Laplace operator, X_pIs the piston displacement of the hydraulic cylinder, C_tpIs the internal leakage coefficient, V, of the hydraulic cylinder_tIs the effective volume of the hydraulic cylinder, and beta e is the effective volume elastic modulus of the hydraulic cylinder; in the formula seven, the first step is carried out,the valve core displacement of an electro-hydraulic servo valve of the electro-hydraulic force control system shown in FIG. 1; in the eighth formula, F_gFor load pressure, m_tFor the total mass of the piston and the load converted to the piston, B_pIs the viscous damping coefficient of the piston and load, and K is the load spring rate.

The first formula to the fourth formula are basic knowledge of the electro-hydraulic control system and are not described in detail here.

And the formula five is an electro-hydraulic servo valve flow equation of the electro-hydraulic force control system.

And the sixth formula is a hydraulic cylinder flow continuity equation of the electro-hydraulic control system.

And the formula seven is an equivalent form of the flow continuity equation of the hydraulic cylinder of the electro-hydraulic control system only provided with the electro-hydraulic servo valve and the flow continuity equation of the hydraulic cylinder of the electro-hydraulic control system.

And the formula eight is a force balance equation of the hydraulic cylinder and the load of the electro-hydraulic control system.

According to the sixth formula and the eighth formula, under the condition that the load pressure is equal to the parameters of the hydraulic cylinder, no matter the system is shown in the figure 1 or the system is shown in the figure 2, the flow Q of the oil inlet cavity of the hydraulic cylinder_LIs a fixed value.

From formula five, formula six and formula eightCompared with the independent oil supply of the electro-hydraulic servo valve of the electro-hydraulic control system only provided with the electro-hydraulic servo valve, the electro-hydraulic proportional speed regulating valve is connected with the electro-hydraulic servo valve in parallel, so that the flow Q flowing into the oil inlet cavity of the hydraulic cylinder_LProvided by both the electro-hydraulic servo valve and the electro-hydraulic proportional speed control valve, and based on the above conclusions for the formula six and the formula eight, the formula seven can be further derived:

is the correct formula.

Calculating formula seven, we can obtain formula nine:

compared with an electro-hydraulic control system only provided with an electro-hydraulic servo valve, the electro-hydraulic control system provided by the invention has the advantages that the valve core displacement of the electro-hydraulic servo valve is smaller, so that the loading speed of the system is further increased when the valve core displacement of the system after the system starts to operate is reduced, and the feedback compensation is performed faster when the system performs feedback, so that the rapidity of the system is improved.