阅读说明：本技术 一种长距离供液恒压控制方法 (Long-distance liquid supply constant-pressure control method ) 是由 王峰 陈金成 于 2021-07-22 设计创作，主要内容包括：本发明公开了一种长距离供液恒压控制方法。在长距离供液的末端并联一个比例节流阀或变量液压马达,采用闭环控制方法,检测液压支架输入端压力,将其与期望压力的差值输入PID控制器,通过调节比例节流阀开度或变量液压马达排量,实现液压支架输入端的恒压控制。本发明方法保持液压支架输入端的压力稳定,有效地降低系统的液压冲击,提高液压支架的速度和位置控制性能。(The invention discloses a constant-pressure control method for long-distance liquid supply. The tail end of the long-distance liquid supply is connected with a proportional throttle valve or a variable hydraulic motor in parallel, the pressure at the input end of the hydraulic support is detected by adopting a closed-loop control method, the difference value between the pressure and the expected pressure is input into a PID controller, and the constant pressure control at the input end of the hydraulic support is realized by adjusting the opening of the proportional throttle valve or the displacement of the variable hydraulic motor. The method of the invention keeps the pressure at the input end of the hydraulic support stable, effectively reduces the hydraulic impact of the system and improves the speed and position control performance of the hydraulic support.)

1. A long-distance liquid supply constant-pressure control method comprises a pump station (1), an electro-hydraulic valve group (2) and a hydraulic support (4), wherein an inlet of the pump station (1) is connected to an oil tank (6), an outlet of the pump station (1) is connected to an inlet end of the electro-hydraulic valve group (2), and an outlet end of the electro-hydraulic valve group (2) is output to the hydraulic support (4); the method is characterized in that: a proportional throttle valve or a variable hydraulic motor is connected in parallel between the outlet of the electro-hydraulic valve group (2) and the oil tank (6), one end of the proportional throttle valve or the variable hydraulic motor (5) is connected with the outlet pipeline of the electro-hydraulic valve group (2), and the other end of the proportional throttle valve or the variable hydraulic motor is connected with the oil tank (6); and the inlet pipeline of the hydraulic support (4) is provided with a pressure sensor (3), and the pressure sensor (3) is used for detecting the pressure of the inlet pipeline of the hydraulic support (4) and feeding back the pressure to the proportional throttle valve or the variable hydraulic motor (5).

2. The constant-pressure control method for long-distance liquid supply as claimed in claim 1, wherein:

obtaining the expected pressure at the input end of the hydraulic support (4) according to the position and speed requirements of the hydraulic support; the method comprises the steps that the current pipeline pressure is detected through a pressure sensor (3) arranged on an inlet pipeline of a hydraulic support (4), the expected pressure is compared with the current pipeline pressure to obtain a pressure difference, the pressure difference is input to a PID controller, the pressure difference is converted into an opening control quantity of a proportional throttle valve or a displacement control quantity of a variable hydraulic motor through the PID controller, the opening of the proportional throttle valve or the displacement of the variable hydraulic motor is adjusted by the opening control quantity/the displacement control quantity to further change the flow passing through the proportional throttle valve or the variable hydraulic motor, and the oil pressure at the inlet of the hydraulic support (4) is kept constant all the time.

3. The constant-pressure control method for long-distance liquid supply as claimed in claim 1, wherein:

the hydraulic support (4) is a hydraulic actuator in a coal mining hydraulic system.

Technical Field

The invention relates to a method for controlling oil supply liquid, in particular to a method for controlling long-distance liquid supply constant pressure, which is particularly suitable for a long-distance liquid supply hydraulic system used in coal mining.

Background

At present, the equipment of the fully mechanized mining face in China develops towards large scale and heavy weight, and the length of the whole machine reaches hundreds of meters, so that long-distance liquid supply is needed. The problems of the prior hydraulic support electrohydraulic system are shown as follows: because the pipeline between the hydraulic support and the power source is long, the long-distance high-pressure large-flow liquid supply power source has delayed response to the load and flow demand of the working surface, so that the pressure and the flow at the input end of the hydraulic support have large fluctuation; the long-distance liquid supply brings about large pressure loss and impact of the system, low reliability of elements and short service life.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a constant-pressure control method for long-distance liquid supply, which solves the problems caused by large fluctuation of pressure and flow at the input end of a hydraulic support due to long pipeline between the hydraulic support and a power source and liquid supply demand response lag, and solves the technical problems of large pressure loss, large impact, low element reliability and short service life of a system caused by long-distance liquid supply.

The technical scheme adopted by the invention is as follows:

the invention comprises a pump station, an electro-hydraulic valve group and a hydraulic support, wherein the inlet of the pump station is connected to an oil tank, the outlet of the pump station is connected to the inlet end of the electro-hydraulic valve group, and the outlet end of the electro-hydraulic valve group is output to the hydraulic support; a proportional throttle valve or a variable hydraulic motor is connected in parallel between the outlet of the electro-hydraulic valve group and the oil tank, one end of the proportional throttle valve or the variable hydraulic motor is connected with the outlet pipeline of the electro-hydraulic valve group, and the other end of the proportional throttle valve or the variable hydraulic motor is connected with the oil tank; and the inlet pipeline of the hydraulic support is provided with a pressure sensor which is used for detecting the pressure of the inlet pipeline of the hydraulic support and feeding the pressure back to the proportional throttle valve or the variable hydraulic motor.

The pump station is a hydraulic device or equipment for outputting a hydraulic power source.

The hydraulic support is a hydraulic actuator.

The electro-hydraulic valve group is used for controlling the hydraulic support and comprises a valve used for controlling the inflow flow of the hydraulic support.

The constant pressure control method of the invention realizes the constant pressure control by a pressure closed loop control.

Obtaining expected pressure at the input end of the hydraulic support according to the position and speed requirements of the hydraulic support; the method comprises the steps that the current pipeline pressure is detected through a pressure sensor arranged on an inlet pipeline of the hydraulic support, the expected pressure is compared with the current pipeline pressure to obtain a pressure difference, the pressure difference is input into a PID controller, the pressure difference is converted into an opening control quantity of a proportional throttle valve or a displacement control quantity of a variable hydraulic motor through the PID controller, the opening control quantity/the displacement control quantity is used for adjusting the opening of the proportional throttle valve or the displacement of the variable hydraulic motor so as to change the flow passing through the proportional throttle valve or the variable hydraulic motor, and the oil pressure at the inlet of the hydraulic support is kept constant all the time.

The long distance is longer than five hundred meters, and is suitable for the problem of unstable pressure fluctuation oil supply liquid caused by the long distance of five hundred meters.

The hydraulic support is a hydraulic actuator in a coal mining hydraulic system.

The invention has the beneficial effects that:

the method can maintain the pressure stability of the input end of the hydraulic support, reduce pressure impact, improve the reliability and the service life of the system, and improve the speed and the position control performance of the hydraulic support.

Drawings

FIG. 1 is a schematic view of a constant pressure liquid supply system for a long distance according to the present invention.

FIG. 2 is a schematic diagram of the constant pressure control method for long distance liquid supply according to the present invention.

Fig. 3 is an embodiment of the present invention.

Fig. 4 is a schematic diagram of a control method according to an embodiment of the present invention.

Fig. 5 is another embodiment of the present invention.

Fig. 6 is a schematic diagram of a control method according to another embodiment of the present invention.

In the figure: the hydraulic control system comprises a pump station 1, an electro-hydraulic valve group 2, a pressure sensor 3, a hydraulic support 4, a proportional throttle valve/variable hydraulic motor 5, an oil tank 6, a proportional throttle valve 7 and a variable hydraulic motor 8.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

As shown in fig. 1, the device structure for concrete implementation comprises a pump station 1, an electro-hydraulic valve group 2 and a hydraulic support 4, wherein an inlet of the pump station 1 is connected to an oil tank 6, an outlet of the pump station 1 is connected to an inlet end of the electro-hydraulic valve group 2, an outlet end of the electro-hydraulic valve group 2 is output to the hydraulic support 4, and an oil discharge end of the hydraulic support 4 is communicated with the oil tank 6;

as shown in fig. 1, a proportional throttle valve or a variable hydraulic motor is connected in parallel between an outlet of the electro-hydraulic valve group 2 and an oil tank 6, one end of the proportional throttle valve or the variable hydraulic motor 5 is connected with an outlet pipeline of the electro-hydraulic valve group 2, and the other end is connected with the oil tank 6; and a pressure sensor 3 is arranged on an inlet pipeline of the hydraulic support 4, and the pressure sensor 3 is used for detecting the pressure of the inlet pipeline of the hydraulic support 4 and feeding the pressure back to a proportional throttle valve or a variable hydraulic motor 5.

The constant voltage control method of the invention has the following control principle:

as shown in fig. 2, the desired pressure at the input of the hydraulic support 4 is obtained according to the position and speed requirements of the hydraulic support; the method comprises the steps that the current pipeline pressure is detected through a pressure sensor 3 arranged at an inlet pipeline of a hydraulic support 4, the expected pressure is compared with the current pipeline pressure to obtain a pressure difference, the pressure difference is input into a PID controller, the pressure difference is converted into an opening control quantity of a proportional throttle valve or a displacement control quantity of a variable hydraulic motor through the PID controller, the opening of the proportional throttle valve or the displacement of the variable hydraulic motor is adjusted through the opening control quantity/the displacement control quantity, and then the flow flowing through the proportional throttle valve or the variable hydraulic motor is changed, so that the oil pressure at the inlet of the hydraulic support 4 is always kept constant, or slowly rises or slowly falls, and finally liquid supply constant pressure control of a long-distance pipeline between an electro-hydraulic valve group 2 and the hydraulic support 4 is achieved.

The hydraulic support 4 is a hydraulic actuator in a coal mining hydraulic system.

The flow demand response lag time t of the pipe depends on the pipe length L and the oil flow velocity v, and is expressed as:then the flow demand response of the pipe lags behind 20s when the oil flow rate is 5m/s for a long distance of 100m for the pipe between the hydraulic mount and the power source.

The pressure fluctuations of the conduit can be represented by the following equation:

wherein B is the volume modulus of the oil,is the amount of pressure fluctuation, q₁For the flow at the input end of the pipeline, q₂The flow rate of the output end of the pipeline. q. q.s₃In order to reduce the output flow of the proportional throttle opening or the displacement of the variable displacement hydraulic motor, V is the volume of a pipeline and is expressed as:

V＝πr²L

wherein_rIs the pipe radius.

When the long distance of the pipeline between the hydraulic support and the power source is 100m, the flow demand response of the pipeline lags by 20 s. In 20s, when the flow required by the hydraulic support, namely the output flow q of the pipeline₂When the pressure changes, the pressure change formula of the pipeline can show that the pipeline existsThe longer the pipe is, the longer the flow demand response lag of the pipe is, and the longer the pipe is, the more severe the pressure fluctuation of the pipe is.

When the flow q required by the hydraulic support is₂When the pressure is increased, the pressure sensor 10 is adopted to detect the current pipeline pressure, if the pressure is 10Mpa, the expected pressure is 11Mpa, the PID controller outputs a negative control signal, and the proportional throttle opening or the displacement of the variable hydraulic motor is reduced to reduce the output flow of the proportional throttle opening or the variable hydraulic motor, so that the pipeline pressure fluctuation is reduced;

when the flow q required by the hydraulic support is₂When reducing, supposing that the pressure sensor 10 detects that the current pipeline pressure is 11Mpa, and the expected pressure is 10Mpa, the PID controller outputs a positive control signal, and increases the proportional throttle opening or the displacement of the variable hydraulic motor to increase the output flow of the proportional throttle opening or the variable hydraulic motor, thereby reducing the pressure fluctuation of the pipeline.

Fig. 3 and 4 illustrate an embodiment of the present invention. The pipeline at the input end of the hydraulic support 4 is connected with a proportional throttle valve 7 in parallel, the PID controller converts the pressure difference between the expected pressure and the current pipeline pressure into the opening of the proportional throttle valve, and the flow passing through the proportional throttle valve is adjusted to realize the constant pressure control of the pressure.

Fig. 5 and 6 show another embodiment of the present invention. The pipeline of the input end of the hydraulic support 4 is connected with a variable hydraulic motor 8 in parallel, the PID controller converts the pressure difference between the expected pressure and the current pipeline pressure into the displacement of the variable hydraulic motor, and the flow passing through the variable hydraulic motor is adjusted to realize the constant pressure control of the pressure.

The foregoing detailed description is intended to be illustrative of the invention, which is only one, but not all embodiments of the invention. Any modification and variation made within the spirit of the present invention and the scope of the claims are within the scope of the present invention.