阅读说明：本技术 超精密液压控制方法 (Ultra-precise hydraulic control method ) 是由 王朝林 张正宁 屈鹏飞 于 2021-02-10 设计创作，主要内容包括：本发明涉及一种油压精确控制的系统。尤其涉及超精密液压控制方法,控制方法为：依次经过三级压力控制的进行压力调节,第一级稳压采用伺服电机驱动所述螺杆泵的油电伺服控制系统,伺服电机由控制中心连接控制的伺服驱动器驱动工作,设置压力传感器进行反馈,对系统压力进行伺服控制PID调节；第二级稳压通过高精度的第一减压阀对系统进行减压稳压,对系统压力进消波处理；第三级稳压同二级稳压相同,通过高精度的第二减压阀对系统压力进行进一步消波处理；第二、三级分别设置稳压器以减小流量脉动对压力的影响,本发明采用三级压力控制提高了控制精度,稳定性好,干扰因素低,洁净度及温度控制减少压力干扰,测压检测及温度检测控制精准。(The invention relates to a system for accurately controlling oil pressure. In particular to an ultra-precise hydraulic control method, which comprises the following steps: the pressure regulation is sequentially carried out through three-stage pressure control, a servo motor is adopted for driving an oil-electricity servo control system of the screw pump in the first-stage pressure stabilization mode, the servo motor is driven to work by a servo driver which is connected and controlled by a control center, a pressure sensor is arranged for feedback, and servo control PID regulation is carried out on the system pressure; the second-stage pressure stabilization is used for carrying out pressure reduction and pressure stabilization on the system through a high-precision first pressure reducing valve, and the pressure of the system is subjected to wave elimination treatment; the third-stage pressure stabilization is the same as the second-stage pressure stabilization, and the system pressure is subjected to further wave elimination treatment through a high-precision second pressure reducing valve; the invention adopts three-level pressure control to improve the control precision, has good stability and low interference factor, reduces the pressure interference by cleanliness and temperature control, and has accurate pressure measurement and temperature detection control.)

1. The ultra-precise hydraulic control method is characterized by comprising the following steps:

the method comprises the following steps: the screw pump sucks oil from the oil tank (1), the outlet of the screw pump is connected with an oil supply loop and an overflow valve (14), and the oil supply loop is provided with a voltage stabilizer to reduce the influence of flow pulsation on pressure;

step two: carrying out first-stage pressure stabilization on oil liquid: the oil-electricity servo control system of the screw pump is driven by a first servo motor (10), the first servo motor (10) is driven by a servo driver which is connected and controlled by a control center to work, a first pressure sensor (15) is arranged at the outlet of the screw pump to feed back, the system pressure is subjected to servo control PID adjustment to ensure the output pressure of the pump source and maintain the pressure stability, meanwhile, the output flow of the oil pump is accurately controlled according to the flow required by the system, and the overflow heat which is more than the oil amount is reduced;

step three: and (3) carrying out second-stage pressure stabilization on oil liquid: the system is decompressed and stabilized through a high-precision first pressure reducing valve (17), and the pressure of the system is subjected to wave elimination treatment;

step four: carrying out third-stage pressure stabilization on oil liquid: the third-stage pressure stabilization is the same as the second-stage pressure stabilization, and the system pressure is further subjected to wave elimination treatment through a high-precision second pressure reducing valve (19).

2. The ultra-precise hydraulic control method according to claim 1, characterized in that: the number of the pressure stabilizers is two, the two pressure stabilizers are respectively arranged in front of a first pressure reducing valve (17) for second-level pressure stabilization and in front of a second pressure reducing valve (19) for third-level pressure stabilization, the pressure stabilizers are energy accumulators or constant pressure sources with elastic compensation, the two pressure stabilizers further improve the compensation response speed in pressure change in the pressure stabilization process of step three and step four, the first pressure reducing valve (17) and the second pressure reducing valve (19) are pressure reducing valves with compensation pipes, and the pressure regulators have the function of compensating downstream pressure drop under the flow conditions of step three and step four.

3. The ultra-precise hydraulic control method according to claim 1, characterized in that: the variable-frequency oil cooler connected with the oil tank transmits a signal to the control center through the first temperature sensor (8), the control center controls the variable-frequency oil cooler to work to control the temperature, the output oil temperature of the system is controlled within the range of +/-0.5 ℃, the precision of the first temperature sensor (8) is less than or equal to 0.2%, and the temperature measurement range of the first temperature sensor (8) is not more than 0-30 ℃.

4. The ultra-precise hydraulic control method according to claim 1, characterized in that:

step five: the fluid through the load gets into oil return circuit, and oil return circuit realizes matching and further promotes the temperature stability by the fluid volume of second servo motor (7) drive oil return pump (6) balanced load and oil tank (1), and the second purpose is: the first servo motor (10) and the second servo motor (7) are connected and cooperatively controlled by a control center to actively stabilize the internal oil pressure of the load.

5. The ultra-precise hydraulic control method according to claim 1, characterized in that:

step two: carrying out first-stage pressure stabilization on oil liquid: the oil-electricity servo control system of the screw pump is driven by a first servo motor (10), the first servo motor (10) is driven by a servo driver which is connected and controlled by a control center to work, a first pressure sensor (15) is arranged at the outlet of the screw pump to feed back, servo control PID adjustment is carried out on system pressure to ensure the output pressure of a pump source and maintain the pressure stability, meanwhile, the output flow of the oil pump is accurately controlled according to the flow required by the system, overflow heating which is more than the oil amount is reduced, a high-pressure oil filter (13) with the filtering precision of 5 mu m is arranged at the outlet of the screw pump, and a differential pressure transmitter is arranged on the high-pressure oil filter (13) to ensure the cleanliness of oil output by.

6. The ultra-precise hydraulic control method according to claim 1, characterized in that:

step four: the second pressure reducing valve (19) outlet is provided with a second pressure sensor (20) and a second temperature sensor (21), and the third-stage pressure stabilization is carried out on oil liquid: the third-stage pressure stabilization is the same as the second-stage pressure stabilization, and the system pressure is further subjected to wave elimination treatment through a high-precision second pressure reducing valve (19);

the second pressure sensor (20) and the second temperature sensor (21) feed back data to the control system and the touch screen.

7. The ultra-precise hydraulic control method according to claim 4, characterized in that:

step five: the fluid through the load gets into oil return circuit, and oil return circuit realizes matching and further promotes the temperature stability by the fluid volume of second servo motor (7) drive oil return pump (6) balanced load and oil tank (1), sets up oil return filter (5) between oil return pump (6) and oil tank (1), magnet (2) adsorb when fluid circulates through fuel feeding return circuit, oil return circuit in oil return filter (5) and oil tank (1), from the metallic magnetic substance of load input and filter.

Technical Field

The invention belongs to the technical field of hydraulic precision control, and particularly relates to an ultra-precision hydraulic control method.

Background

The precision control hydrostatic pressure output is widely applied to high-precision machining processes, such as hydrostatic bearings, hydrostatic guide rails and the like, the constant pressure control precision of the current precision hydraulic oil source control technology is generally more than 1 per thousand, and higher precision less than 1 per thousand is difficult to realize or difficult to stably maintain.

Disclosure of Invention

The invention discloses a precise hydraulic oil source control loop for realizing stable output of high-precision oil pressure.

The invention adopts the following technical scheme:

accurate hydraulic pressure oil source control circuit, the fuel feeding return circuit that hydraulic pump output connection control valve, energy storage ware, sensor, overflow valve are constituteed including first servo motor drive, its characterized in that: still include return oil circuit and cooling circuit, control center, the hydraulic pump is the screw pump, and the control valve includes first relief pressure valve, second relief pressure valve, and the energy storage ware includes: first accumulator, second accumulator, the sensor includes: the first pressure sensor, the first temperature sensor and the liquid level relay are connected, the oil suction port of the hydraulic pump is connected with an oil tank, the first temperature sensor and the liquid level relay are arranged in the oil tank, the pressure port of the hydraulic pump is sequentially connected with the first pressure sensor and the first pressure reducing valve, the second relief pressure valve, second relief pressure valve exit linkage load, first pressure sensor, connect between the first relief pressure valve and set up first energy storage ware, first relief pressure valve, it sets up the second energy storage ware to connect between the second relief pressure valve, the oil return pump of oil return circuit for connecting load and oil tank, the oil return pump is connected by the drive of second servo motor, cooling circuit is the oil cooler of external connection oil tank, first servo motor, second servo motor sets up respectively and is connected with servo driver, servo driver is the connection control center respectively, first pressure sensor, first temperature sensor input connection control center, control center connects the touch-sensitive screen that sets up input \ output.

A second pressure sensor and a second temperature sensor are also connected between the outlet of the second pressure reducing valve and the load, and the inputs of the second pressure sensor and the second temperature sensor are connected with the control center; an oil return filter is connected between the oil return pump and the oil tank; a high-pressure oil filter is connected between the hydraulic pump and the first pressure sensor, the hydraulic pump is preferably a screw pump, the high-pressure oil filter is provided with a differential pressure transmitter, and the oil cooler is preferably a variable-frequency oil cooler; pressure measuring points are respectively arranged at the inlet and the outlet of the first pressure reducing valve and the second pressure reducing valve; the bottom in the oil tank is provided with a magnet.

The ultra-precise hydraulic control method comprises the following steps:

the method comprises the following steps: the screw pump sucks oil from the oil tank, the outlet of the screw pump is connected with an oil supply loop and an overflow valve, and the oil supply loop is provided with a voltage stabilizer to reduce the influence of flow pulsation on pressure;

step two: carrying out first-stage pressure stabilization on oil liquid: the oil-electricity servo control system of the screw pump is driven by a first servo motor, the first servo motor is driven by a servo driver which is connected and controlled by a control center to work, a first pressure sensor is arranged at the outlet of the screw pump to feed back, the system pressure is subjected to servo control PID adjustment to ensure the output pressure of a pump source and maintain the pressure stability, meanwhile, the output flow of the oil pump is accurately controlled according to the flow required by the system, and the overflow heating which is more than the oil amount is reduced;

step three: and (3) carrying out second-stage pressure stabilization on oil liquid: the system is subjected to pressure reduction and stabilization through a high-precision first pressure reducing valve, and the pressure of the system is subjected to wave elimination treatment;

step four: carrying out third-stage pressure stabilization on oil liquid: the third-stage pressure stabilization is the same as the second-stage pressure stabilization, and the system pressure is subjected to further wave elimination treatment through a high-precision second pressure reducing valve.

The number of the pressure stabilizers is two, the pressure stabilizers are respectively arranged in front of a first pressure reducing valve for second-stage pressure stabilization and in front of a second pressure reducing valve for third-stage pressure stabilization, the pressure stabilizers are energy accumulators or constant pressure sources with elastic compensation, the two pressure stabilizers further improve the compensation response speed in pressure change in the pressure stabilizing process of the third step and the fourth step, the first pressure reducing valve and the second pressure reducing valve are pressure reducing valves with compensation pipes, and the pressure regulators have the function of compensating downstream pressure drop under the flow conditions of the third step and the fourth step.

The variable-frequency oil cooler connected with the oil tank transmits a signal to the control center through the first temperature sensor, the control center controls the variable-frequency oil cooler to work to control the temperature, the output oil temperature of the system is controlled within the range of +/-0.5 ℃, the precision of the first temperature sensor is less than or equal to 0.2%, and the temperature measurement range of the first temperature sensor is not more than 0-30 ℃.

Step five: fluid through the load gets into oil return circuit, and oil return circuit realizes matching and further promotes the temperature stability by the fluid volume of second servo motor drive oil return pump balanced load and oil tank, and the second purpose is: the first servo motor and the second servo motor are connected and cooperatively controlled by the control center to actively stabilize the internal oil pressure of the load.

Step two: carrying out first-stage pressure stabilization on oil liquid: the oil-electricity servo control system of the screw pump is driven by a first servo motor, the first servo motor is driven by a servo driver connected and controlled by a control center to work, a first pressure sensor is arranged at the outlet of a screw pump for feedback, servo control PID adjustment is carried out on system pressure to guarantee pump source output pressure and maintain pressure stability, meanwhile, the output flow of an oil pump is accurately controlled according to the flow required by the system, overflow heating which is more than oil is reduced, a high-pressure oil filter with the filtering precision of 5 mu m is arranged at the outlet of the screw pump, and a differential pressure transmitter is arranged on the high-pressure oil filter to guarantee the cleanliness of oil output by the system and avoid affecting.

Step four: the second relief pressure valve outlet is provided with second pressure sensor, second temperature sensor, carries out tertiary steady voltage to fluid: the third-stage pressure stabilization is the same as the second-stage pressure stabilization, and the system pressure is subjected to further wave elimination treatment through a high-precision second pressure reducing valve;

and the second pressure sensor and the second temperature sensor feed back data to the control system and the touch screen.

Step five: the oil liquid passing through the load enters an oil return loop, the oil return loop is driven by a second servo motor to balance the oil amount of the load and the oil amount of an oil tank so as to realize matching and further promote temperature stability, an oil return filter is arranged between the oil return pump and the oil tank, and when the oil liquid circulates through the oil supply loop and the oil return loop, metal magnetic substances input from the load are adsorbed and filtered by magnets in the oil return filter and the oil tank.

Compared with the prior art, the invention can obtain the following technical effects: the pressure control precision of accurate hydraulic pressure oil source control circuit is high, and stability is good, and interference factor is low, and tertiary pressure control steady voltage is effectual, and external temperature control saves space and reduces pressure interference, and pressure measurement detection and temperature detection control are accurate.

The precise hydraulic oil source control loop has complete functions and high precision.

Drawings

FIG. 1 is a schematic diagram of the present invention;

FIG. 2 is a control block diagram of the present invention;

FIG. 3 is a flow chart of the present invention;

fig. 4 is a graph showing the pressure control change per unit time according to the present invention.

The system comprises an oil tank 1, a magnet 2, a liquid level meter 3, a filter 4, an oil return filter 5, an oil return pump 6, a second servo motor 7, a first temperature sensor 8, a liquid level relay 9, a first servo motor 10, a hydraulic pump 11, a cooler 12, a high-pressure oil filter 13, an overflow valve 14, a first pressure sensor 15, a first energy accumulator 16, a first pressure reducing valve 17, a second energy accumulator 18, a second pressure reducing valve 19, a second pressure sensor 20 and a second temperature sensor 21.

Detailed Description

The ultra-precise hydraulic control loop comprises an oil supply loop, an oil return loop and a cooling loop which are respectively connected with the oil tank 1;

as shown in fig. 1, the cooling system comprises an oil supply loop, an oil return loop and a cooling loop which are respectively connected with an oil tank 1;

wherein, the oil supply circuit includes: hydraulic pump 11, relief pressure valve, energy storage ware, overflow valve 14, the high-pressure oil filter of first servo motor 10 driven, oil tank 1 is connected to 11 oil intakes of hydraulic pump, and hydraulic pump 11 exit linkage high-pressure oil filter 13, high-pressure oil filter 13 exit linkage overflow valve 14, and 14 oil return connection oil tanks 1 of overflow valve, the energy storage ware includes first energy storage ware 16, second energy storage ware 18, and the relief pressure valve includes: the outlet of the high-pressure oil filter 13 is connected with a first accumulator 16 and a first pressure reducing valve 17, the outlet of the first pressure reducing valve 17 is connected with a second accumulator 18 and a second pressure reducing valve 19, the outlet of the second pressure reducing valve 19 is connected with an A port for supplying oil to a load, and the outlet of the high-pressure oil filter 13 is connected with a first pressure sensor 15; the hydraulic pump 11 is preferably a screw pump.

Preferably, the high-pressure oil filter 13 is provided with a differential pressure transmitter LF.

Furthermore, a second pressure sensor 20 and a second temperature sensor 21 are also connected to the outlet of the second pressure reducing valve 19.

The bottom in the oil tank 1 is provided with a magnet 2 for absorbing magnetic metal powder impurities.

The oil return circuit includes: an oil return pump 6 and an oil return filter 5 driven by a second servo motor 7, wherein the port B is an oil return port and is connected with a load, the port B is connected with the oil return pump 6, the output of the oil return pump 6 is connected with the oil return filter 5, and the output of the oil return filter 5 is connected with the oil tank 1.

The cooling loop is a cooler 12 with an inlet and an outlet respectively connected with the oil tank 1, the frequency conversion oil cooler is preferably selected as the cooler 12, and the oil tank 1 is also provided with a first temperature sensor 8, a liquid level relay 9 and a liquid level meter 3.

As shown in fig. 2, the liquid level relay 9, the first temperature sensor 8, the first pressure sensor 15, the second pressure sensor 20, and the second temperature sensor 21 are connected to a feedback signal of the control center, the control center outputs a signal to the drivers connected to the first servo motor 10 and the second servo motor 7, the control center is connected to the touch screen and the cooler, the touch screen inputs and outputs a signal to the control center, and the differential pressure transmitter LF is connected to the feedback signal of the control center.

The working mode is as follows:

as shown in figures 1-3, the invention has small fluctuation of the output pressure requirement, and adopts the overall scheme of three-level pressure stabilization and pressure reduction to achieve ultra-precise pressure control with the pressure fluctuation less than 0.5 per mill.

The first servo motor 10 drives the hydraulic pump 11 to pump hydraulic oil out of the oil tank 1, the pressure oil is output to the port A through the high-pressure oil filter 13, the first energy accumulator 16, the first pressure reducing valve 17, the second energy accumulator 18 and the second pressure reducing valve 19 in sequence, the first pressure sensor 15 feeds back pressure to the oil-electricity servo control system, and the second pressure sensor 20 and the second temperature sensor 21 feed back data to the control system and the touch screen.

The first-stage pressure stabilization adopts an oil-electricity servo control system of a first servo motor 10 to drive a hydraulic pump 11, servo control is carried out on system pressure to ensure the stability of pump source output pressure and pressure, meanwhile, the output flow of the oil pump can be accurately controlled according to the required flow of the system, overflow heat of more than oil mass is reduced, and the system is more stable. The hydraulic pump 11 adopts a screw pump to reduce pressure fluctuation caused by the oil pump and simultaneously reduce noise of the system. The highest primary output pressure is: 4Mpa, the maximum flow is more than or equal to 12L/min, the outlet pressure range of the port A is 0.5-2.0 Mpa, and the pressure is continuously adjustable.

The second level steady voltage is carried out the steady voltage of decompression through the first relief pressure valve 17 of high accuracy to the system, carries out the wave elimination to system pressure and handles, has set up the first energy storage ware 16 of stabiliser and has reduced the influence of flow pulsation to pressure, steady voltage output pressure, decompression scope: 0.6-0.9 MPa.

The third level steady voltage is the same with second steady voltage and carries out further wave elimination processing through the second relief pressure valve 19 of high accuracy to system pressure, has set up stabiliser second energy storage ware 18 and has reduced the influence of flow pulsation to pressure, further improves output pressure's stability, finally reaches system requirements, decompression scope: 0.6-0.9 MPa.

The high-pressure oil outlet is provided with a first pressure sensor 15 with the accuracy less than 0.04, and the output pressure is detected. When the pressure of the high-pressure oil outlet is lower than or higher than a set value, the system buzzes to alarm and displays on the touch screen.

The system output oil temperature is controlled within the range of +/-0.5 ℃, the first temperature sensor 8 and the variable-frequency oil cooler with the accuracy of less than or equal to 0.2% are adopted to control the temperature of oil in the oil tank, the temperature measuring range of the first temperature sensor 8 is not less than 0-30 ℃, the oil temperature sensor is used for detecting the temperature of the oil to control the refrigerating capacity of the oil cooler to achieve the accurate control of the oil temperature, and the stable working states of all valves of the oil supply system generate the same heat, so that the output temperature is accurately controlled. When the temperature of the oil tank exceeds a set value, a buzzer alarms and is displayed on the touch screen.

The high-pressure oil filter 13 has the filtering precision of 5 mu m, and the cleanliness of the oil output by the system is ensured.

The system is provided with an oil return pump 6 and a liquid level relay 9 which are driven by a servo motor 7, the system can accurately adjust the oil pumping flow according to the actual use condition, the matching performance of the oil return and the output oil quantity of the system is ensured, the normal work of the system is ensured, meanwhile, the oil level is detected in real time through a liquid level sensor, the fault alarm is timely carried out, the first servo motor 10 and the second servo motor 7 are connected and cooperatively controlled by a control center, and the internal oil pressure of the load is actively stabilized.

Adjusting a precision hydraulic system:

and adjusting the pressure value of a P port of the hydraulic pump 11, adjusting the overflow valve 14 to 4MPa, inputting a pressure set value in a touch screen connected with a control center, observing the pressure value of the P port on a display screen, and adjusting a PID parameter value in a control center system through the touch screen to enable the pressure to be stabilized within +/-0.02 MPa of the set value. And (5) repeatedly setting the pressure value for many times to meet the requirement.

The pressure value of the port A is adjusted, after the pressure precision of the port P of the hydraulic pump 11 meets the requirement, the port A is connected with a load, the first pressure reducing valve 17 and the second pressure reducing valve 19 are respectively adjusted, the pressure value of the port A on the display screen is observed, the pressure value required in the working process is achieved by adjusting PID parameter values in a control center system, as shown in figure 4, the pressure fluctuation value is not more than +/-0.001 MPa, and the overshoot is not more than 0.1 MPa. The second servomotor 7 drives the scavenge pump 6 to draw scavenge oil from the load connected to port B to the scavenge filter 5 into the tank 1.