阅读说明：本技术 微量液体出液的压力控制装置及其压力控制方法 (Pressure control device and pressure control method for micro-liquid outflow ) 是由 王强 蒋波 曲东升 王栋梁 马成稳 闵继江 李长峰 于 2021-08-26 设计创作，主要内容包括：本发明涉及微量液体出液技术领域,本发明提供了一种微量液体出液的压力控制装置,包括总控制系统、液体储存器、挤压单元、喷嘴、压力控制单元、挤压控制单元和执行元件,液体储存器和挤压单元之间通过上流道相连通,挤压单元与喷嘴之间通过下流道相连通,上流道上设置有上流道压力传感器,下流道上设置有下流道压力传感器。本发明还提供了一种微量液体出液的压力控制方法,上流道压力传感器和下流道压力传感器分别对上流道和下流道的压力进行检测,执行元件对上流道的压力进行调节从而调节上流道与下流道的压力比值。本发明在液体存储单元液位变化或液体粘度变化时对上流道压力进行调节,从而实现挤压出的液滴大小均匀。(The invention relates to the technical field of micro liquid outflow, and provides a pressure control device for micro liquid outflow, which comprises a master control system, a liquid storage device, an extrusion unit, a nozzle, a pressure control unit, an extrusion control unit and an execution element, wherein the liquid storage device is communicated with the extrusion unit through an upper flow passage, the extrusion unit is communicated with the nozzle through a lower flow passage, an upper flow passage pressure sensor is arranged on the upper flow passage, and a lower flow passage pressure sensor is arranged on the lower flow passage. The invention also provides a pressure control method for the micro liquid outlet, wherein the pressure sensors of the upper flow passage and the lower flow passage respectively detect the pressure of the upper flow passage and the pressure of the lower flow passage, and the executive element regulates the pressure of the upper flow passage so as to regulate the pressure ratio of the upper flow passage and the lower flow passage. The invention adjusts the pressure of the upper flow passage when the liquid level of the liquid storage unit changes or the viscosity of the liquid changes, thereby realizing the uniform size of the extruded liquid drops.)

1. A pressure control device for micro liquid outflow is characterized in that: including total control system (1), liquid storage ware (2), extrusion unit (3), nozzle (4), pressure control unit (5) and extrusion control unit (6), pressure control unit (5) are linked together with liquid storage ware (2), be linked together through last runner (7) between liquid storage ware (2) and the extrusion unit (3), extrusion control unit (6) are linked together with extrusion unit (3), extrusion control unit (6) and pressure control unit (5) all are connected with total control system (1) electricity, be linked together through lower runner (8) between extrusion unit (3) and nozzle (4), upward be provided with runner pressure sensor (9) on runner (7), be provided with down runner pressure sensor (10) on lower runner (8), upward runner pressure sensor (9), The lower runner pressure sensors (10) are electrically connected with the master control system (1), the upper runner pressure sensor (9) detects the pressure of the upper runner (7), the detection value is recorded as a, the lower runner pressure sensor (10) detects the pressure of the lower runner (8), and the detection value is recorded as b, the device further comprises an execution element for adjusting the pressure of the upper runner (7), and the execution element is connected with the master control system (1) to control the execution element through the master control system (1).

2. The apparatus for controlling the pressure of a trace amount of liquid as set forth in claim 1, wherein: the liquid storage device is characterized in that a flow control valve (11) is arranged on the upper flow channel (7), the flow control valve (11) is an execution element, the flow control valve (11) is located between the upper flow channel pressure sensor (9) and the liquid storage device (2), and the flow control valve (11) is electrically connected with the master control system (1).

3. The apparatus for controlling the pressure of a trace amount of liquid as set forth in claim 1, wherein: the upper flow channel pressure sensor (9) and the lower flow channel pressure sensor (10) are connected with the master control system (1) through analog quantity signals and high-speed communication links.

4. A pressure control method for micro liquid outflow is characterized in that: the pressure control method of the micro-scale liquid outlet is realized by using the pressure control device of the micro-scale liquid outlet as claimed in any one of claims 1 to 3, and comprises the following steps:

s1, setting the ratio of the pressure of the upper flow channel (7) to the pressure of the lower flow channel (8) in the master control system (1), and recording the set value as c;

s2, the master control system (1) controls the pressure control unit (5) to provide positive pressure for the liquid storage (2), so that the liquid in the liquid storage (2) flows to the upper flow passage (7), the extrusion unit (3), the lower flow passage (8) and the nozzle (4);

s3, the master control system (1) controls the extrusion control unit (6) to provide positive pressure for the extrusion unit (3) so as to extrude the liquid in the extrusion unit (3) to the nozzle (4), and the liquid in the nozzle (4) flows out from the nozzle (4) to the workpiece;

s4, in the liquid discharging process of the nozzle (4), the upper flow channel pressure sensor (9) detects the pressure of the upper flow channel (7) in real time, the detected value is recorded as a1, the detected value a1 is transmitted to the master control system (1), meanwhile, the lower flow channel pressure sensor (10) detects the pressure of the lower flow channel (8) in real time, the detected value b1 is recorded as b1, and b1 is transmitted to the master control system (1);

and S5, calculating the value of a1/b1, namely d, by the general control system (1), calculating the difference between d and c by optimizing a PID control algorithm, and controlling an actuating element to adjust the pressure of the upper flow channel (7) so that the ratio of the pressure of the upper flow channel (7) to the pressure of the lower flow channel (8) is c.

5. The method for controlling the pressure of a trace amount of liquid outlet as set forth in claim 4, wherein: the step S5 includes:

s51, the master control system (1) calculates a d-c value, the d-c value is recorded as delta e, the master control system (1) judges the size relation between the delta e and 0, if the delta e is larger than 0, the master control system (1) controls the flow control valve (11), the flow control valve (11) increases the flow of the upper flow channel (7), the pressure of the upper flow channel (7) is reduced, and the step S4 is continuously executed;

s52, the master control system (1) calculates a d-c value, the d-c value is recorded as delta e, the master control system (1) judges the size relation between the delta e and 0, if the delta e is smaller than 0, the master control system (1) controls the flow control valve (11), the flow control valve (11) reduces the flow of the upper flow channel (7), the pressure of the upper flow channel (7) is increased, and the step S4 is continuously executed;

s53, the master control system (1) calculates the value of d-c and records the value as delta e, the master control system (1) judges the size relation between delta e and 0, and if delta e is equal to 0, the step S4 is continuously executed.

6. The method for controlling the pressure of a trace amount of liquid outlet as set forth in claim 4, wherein: the step S5 includes:

s51', the master control system (1) calculates the value d-c, the value d-c is recorded as delta e, the master control system (1) judges the size relation between delta e and 0, if delta e is larger than 0, the master control system (1) controls the pressure control unit (5), the pressure control unit (5) reduces the output pressure of the liquid storage device (2), so that the pressure of the upper flow channel (7) is reduced, and the step S4 is continuously executed;

s52', the master control system (1) calculates the value d-c, the value d-c is recorded as delta e, the master control system (1) judges the size relation between delta e and 0, if the delta e is smaller than 0, the master control system (1) controls the pressure control unit (5), the pressure control unit (5) increases the output pressure of the liquid storage device (2), so that the pressure of the upper flow channel (7) is increased, and the step S4 is continuously executed;

s53', the total control system (1) calculates the value of d-c and records the value as delta e, the total control system (1) judges the size relation between delta e and 0, and if delta e is equal to 0, the step S4 is continuously executed.

7. The method for controlling the pressure of a trace amount of liquid outlet as set forth in claim 4, wherein: in step S1, the value of c is set to 1:10 to 1: 1000.

8. The method for controlling the pressure of a trace amount of liquid outlet as set forth in claim 4, wherein: in step S3, when the squeeze control unit (6) applies positive pressure to the squeeze unit (3), most of the liquid flows along the upper flow path (7) to the liquid reservoir (2), and only a small amount of the liquid flows out from the nozzle (4) along the lower flow path (8).

9. The method for controlling the pressure of a trace amount of liquid outlet as set forth in claim 4, wherein: in the step S4, the general control system (1) performs collection value filtering processing on the collected a1 and b1 data to eliminate collection values with large errors.

Technical Field

The invention relates to the technical field of micro liquid discharge, in particular to a pressure control device and a pressure control method for micro liquid discharge.

Background

At present, the application of the dispensing technology in many fields is more and more extensive, and the dispensing technology plays a crucial role from the welding, coating and sealing of semiconductor packaging, integrated circuit industry, SMT/PCB assembly to general industry. The dispensing technology is to dispense fluid to a designated position of a product, so as to realize functions of fixing, encapsulating, welding and the like of electronic components. In the electronic manufacturing process, when electronic components need to be assembled together, glue is distributed to a designated position by a glue dispensing technology to bond the components, so that the components are assembled; when the electronic components need to be connected with each other, the solder paste, the silver paste and the like are distributed to designated positions by a dispensing technology, so that the electronic components are connected.

The electronic packaging has higher and higher precision requirement and efficiency for dispensing, and the volume of the dispensing glue solution is smaller and smaller. Particularly, for the packaging of the semiconductor industry and the LED industry, the requirement on micron-sized high-precision micro-dispensing is very urgent. At present, micro-scale screw valves, injection valves and the like are mainly adopted for micro-dispensing at home and abroad, the minimum point diameter and the minimum line diameter of the injection valves can be 200 mu m, and the minimum point diameter and the minimum line diameter of the screw valves can be 700 mu m, and if the point diameter or the line diameter of less than 200 mu m is to be realized, an extrusion type micro-liquid dispensing device is required.

Because the size of the liquid drop extruded by the extrusion valve is closely related to the pressure difference between the upper flow passage and the lower flow passage, the existing control method generally extrudes the liquid storage unit and the extrusion cavity by fixing air pressure and time, the liquid level or the liquid viscosity in the liquid storage unit is changed and cannot be detected, the control parameters cannot ensure the consistency of the size of the extruded liquid drop, and the extruded liquid drop is uneven in size.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: in order to solve the technical problem that the size of extruded liquid drops is not uniform when the liquid level or the liquid viscosity in a liquid storage unit changes in the prior art, the invention provides a pressure control method of a trace liquid outlet device, which realizes stable pressure difference between an upper flow passage and a lower flow passage and realizes uniform size of the extruded liquid drops when the liquid level or the liquid viscosity of the liquid storage unit changes.

The technical scheme adopted by the invention for solving the technical problems is as follows: a pressure control device for micro liquid outflow comprises a master control system, a liquid storage, an extrusion unit, a nozzle, a pressure control unit and an extrusion control unit, wherein the pressure control unit is communicated with the liquid storage, the liquid storage is communicated with the extrusion unit through an upper flow passage, the extrusion control unit is communicated with the extrusion unit, the extrusion control unit and the pressure control unit are both electrically connected with the master control system, the extrusion unit is communicated with the nozzle through a lower flow passage, an upper flow passage pressure sensor is arranged on the upper flow passage, a lower flow passage pressure sensor is arranged on the lower flow passage, the upper flow passage pressure sensor and the lower flow passage pressure sensor are both electrically connected with the master control system, the upper flow passage pressure sensor detects the pressure of the upper flow passage, a detection value is marked as a, and the lower flow passage pressure sensor detects the pressure of the lower flow passage, the detection value is b, and the device further comprises an execution element for adjusting the pressure of the upper flow passage, and the execution element is connected with the master control system to control the execution element through the master control system.

The invention detects the pressure of the upper flow passage in real time through the upper flow passage pressure sensor, when the liquid level in the liquid storage device changes, the pressure of the upper flow passage changes, the upper flow passage pressure sensor and the lower flow passage pressure sensor transmit the detected pressure values to the master control system, the master control system calculates the deviation between the pressure ratio of the upper flow passage and the lower flow passage and a set value, and controls the execution element to regulate the pressure of the upper flow passage through the PID control algorithm, so that the pressure ratio of the upper flow passage and the lower flow passage is stabilized at the set value, the liquid output of liquid drops extruded from the nozzle is uniform, the phenomena of leakage and large droplet are avoided, and the liquid output quality is improved.

Furthermore, a flow control valve is arranged on the upper runner, the flow control valve is an execution element, the flow control valve is positioned between the upper runner pressure sensor and the liquid storage, and the flow control valve is electrically connected with the master control system.

Furthermore, the upper flow channel pressure sensor and the lower flow channel pressure sensor are both connected with a master control system through analog quantity signals and a high-speed communication link. The pressure values of the upper flow channel and the lower flow channel can be rapidly collected in real time, and the timeliness and the accuracy of pressure data collection are improved.

The invention also provides a pressure control method for the micro liquid outlet, which comprises the following steps:

s1, setting the ratio of the pressure of the upper runner to the pressure of the lower runner in the master control system, and recording the set value as c;

s2, the master control system controls the pressure control unit to provide positive pressure for the liquid storage device, so that the liquid in the liquid storage device flows to the upper flow channel, the extrusion unit, the lower flow channel and the nozzle;

s3, the master control system controls the extrusion control unit to provide positive pressure for the extrusion unit so as to extrude the liquid in the extrusion unit to the nozzle, and the liquid in the nozzle flows out of the nozzle to the workpiece;

s4, in the liquid outlet process of the nozzle, the pressure sensor of the upper runner detects the pressure of the upper runner in real time, the detection value is recorded as a1, the detection value a1 is transmitted to the master control system, meanwhile, the pressure sensor of the lower runner detects the pressure of the lower runner in real time, the detection value is recorded as b1, and b1 is transmitted to the master control system;

s5, the master control system calculates the value of a1/b1, which is recorded as d, and calculates the difference between d and c by optimizing a PID control algorithm, so that the actuator is controlled to adjust the pressure of the upper flow channel, and the ratio of the pressure of the upper flow channel to the pressure of the lower flow channel is c.

Further, the step S5 includes:

s51, the master control system calculates the value of d-c and records as delta e, the master control system judges the size relation between delta e and 0, if delta e is larger than 0, the master control system controls the flow control valve, the flow control valve increases the flow of the upper flow channel, the pressure of the upper flow channel is reduced, and the step S4 is continuously executed;

s52, the master control system calculates the value of d-c and records as delta e, the master control system judges the size relation between delta e and 0, if delta e is smaller than 0, the master control system controls the flow control valve, the flow control valve reduces the flow of the upper flow channel, the pressure of the upper flow channel is increased, and the step S4 is continuously executed;

and S53, calculating the value of d-c by the master control system, recording the value as delta e, judging the size relation between delta e and 0 by the master control system, and if the delta e is equal to 0, continuing to execute the step S4.

Further, the step S5 includes:

s51', the master control system calculates the value of d-c and records as delta e, the master control system judges the size relation between delta e and 0, if delta e is larger than 0, the master control system controls the pressure control unit, the pressure control unit reduces the output pressure of the liquid storage device, the pressure of the upper flow passage is reduced, and the step S4 is continuously executed;

s52', the master control system calculates the value of d-c and records as delta e, the master control system judges the size relation between delta e and 0, if delta e is smaller than 0, the master control system controls the pressure control unit, the pressure control unit increases the output pressure of the liquid storage device, the pressure of the upper flow passage is increased, and the step S4 is continuously executed;

s53', the master control system calculates the value of d-c and records as delta e, the master control system judges the size relation between delta e and 0, if delta e is equal to 0, the step S4 is continuously executed.

Further, the value of c in step S1 is set to 1:10 to 1: 1000. When the liquid outlet amount of the nozzle is controlled, the pressure of the upper flow passage and the lower flow passage is controlled, so that the resistance ratio of the liquid in the upper flow passage and the liquid in the lower flow passage is controlled, the resistance of the liquid in the upper flow passage is far smaller than that of the lower flow passage, therefore, when the extrusion control unit extrudes the extrusion unit, a larger part of the liquid in the liquid flow passage in the extrusion unit flows to the liquid storage along the upper flow passage, only a small part flows to the nozzle along the lower flow passage, the amount of the liquid in the liquid flow passage in the extrusion unit flowing to the upper flow passage and the lower flow passage can be changed by adjusting the set value of c, so that the liquid outlet amount of the nozzle is convenient to adjust, compared with the method that the liquid outlet amount of the nozzle is adjusted by adjusting the deformation amount of the liquid flow passage in the extrusion unit, the adjustment mode is simple and convenient, and the pressure of the upper flow passage and the lower flow passage can be detected by the pressure sensor of the upper flow passage and the lower flow passage, thereby improving the uniformity of the liquid outlet quantity of the nozzle and improving the stability of the liquid outlet of the nozzle.

Further, in step S3, when the pressing control unit applies positive pressure to the pressing unit, most of the liquid flows along the upper flow path to the liquid reservoir, and only a small amount of the liquid flows out of the nozzle along the lower flow path. When the extrusion unit is deformed by extrusion force, the liquid in the extrusion unit is pushed to flow along the upper flow channel and the lower flow channel, most of the liquid flows along the upper flow channel, and only a very small amount of liquid flows out along the lower flow channel, so that the liquid outlet of the small amount of liquid is realized conveniently.

Further, in step S4, the overall control system performs collection value filtering processing on the collected data a1 and b1 to eliminate collection values with large errors. The pressure control of the upper flow channel is prevented from generating errors by the acquisition values with larger errors.

The pressure control method of the micro liquid outlet has the advantages that the pressure sensor of the upper flow passage detects the pressure of the upper flow passage in real time, when the liquid level in the liquid storage device changes, the pressure of the upper flow passage changes, the pressure sensor of the upper flow passage and the pressure sensor of the lower flow passage transmit the detected pressure values to the master control system, the master control system calculates the deviation between the pressure ratio of the upper flow passage and the lower flow passage and the set value, and controls the execution element to regulate the pressure of the upper flow passage through the PID control algorithm, so that the pressure ratio of the upper flow passage and the lower flow passage is stabilized at the set value, the liquid outlet quantity of liquid drops extruded from the nozzle is uniform, the phenomena of leakage and large droplet are avoided, and the liquid outlet quality is improved;

when the liquid outlet amount of the nozzle is controlled, the pressure of the upper flow passage and the lower flow passage is controlled, so that the resistance ratio of the liquid in the upper flow passage and the liquid in the lower flow passage is controlled, the resistance of the liquid in the upper flow passage is far smaller than that of the lower flow passage, therefore, when the extrusion control unit extrudes the extrusion unit, a larger part of the liquid in the liquid flow passage in the extrusion unit flows to the liquid storage along the upper flow passage, only a small part flows to the nozzle along the lower flow passage, the amount of the liquid in the liquid flow passage in the extrusion unit flowing to the upper flow passage and the lower flow passage can be changed by adjusting the set value of c, so that the liquid outlet amount of the nozzle is convenient to adjust, compared with the method that the liquid outlet amount of the nozzle is adjusted by adjusting the deformation amount of the liquid flow passage in the extrusion unit, the adjustment mode is simple and convenient, and the pressure of the upper flow passage and the lower flow passage can be detected by the pressure sensor of the upper flow passage and the lower flow passage, thereby improving the uniformity of the liquid outlet quantity of the nozzle and improving the stability of the liquid outlet of the nozzle.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic view of a pressure control apparatus for a minute amount of liquid discharge in example 1 of the present invention.

FIG. 2 is a flow chart of the method for controlling the pressure of the micro-liquid outlet liquid.

Fig. 3 is a flowchart illustrating step S5 in embodiment 1 of the present invention.

FIG. 4 is a schematic view of a pressure control apparatus for a minute amount of liquid-out in example 2 of the present invention.

Fig. 5 is a flowchart illustrating step S5 in embodiment 2 of the present invention.

In the figure: 1. a master control system; 2. a liquid reservoir; 3. a pressing unit; 4. a nozzle; 5. a pressure control unit; 6. a squeezing control unit; 7. an upper flow passage; 8. a lower runner; 9. an upper flow channel pressure sensor; 10. a lower flow path pressure sensor; 11. a flow control valve.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1: as shown in fig. 1 to 3, which are the most preferred embodiments of the present invention, a pressure control device for micro-amount liquid outflow includes a main control system 1, a liquid reservoir 2, an extrusion unit 3, a nozzle 4, a pressure control unit 5 and an extrusion control unit 6, wherein the pressure control unit 5 is communicated with the liquid reservoir 2, the liquid reservoir 2 is communicated with a liquid channel in the extrusion unit 3 through an upper channel 7, the extrusion control unit 6 is communicated with the extrusion unit 3, both the extrusion control unit 6 and the pressure control unit 5 are electrically connected to the main control system 1, and the liquid channel of the extrusion unit 3 is communicated with the nozzle 4 through a lower channel 8. The device also comprises an actuating element for adjusting the pressure of the upper flow passage, and the actuating element is connected with the master control system so as to control the actuating element through the master control system.

The upper runner 7 is provided with an upper runner pressure sensor 9, the lower runner 8 is provided with a lower runner pressure sensor 10, the upper runner pressure sensor 9 and the lower runner pressure sensor 10 are electrically connected with the master control system 1, the upper runner pressure sensor 9 and the lower runner pressure sensor 10 are connected with the master control system 1 through analog quantity signals and high-speed communication links, the pressure values of the upper runner 7 and the lower runner 8 can be rapidly acquired in real time, and the timeliness and the accuracy of acquiring pressure data are improved.

The upper flow path pressure sensor 9 detects the pressure in the upper flow path 7, and the detection value is denoted as a, and the lower flow path pressure sensor 10 detects the pressure in the lower flow path 8, and the detection value is denoted as b.

The upper flow channel 7 is provided with a flow control valve 11, an execution element is the flow control valve 11, the flow control valve 11 is positioned between the upper flow channel pressure sensor 9 and the liquid storage 2, and the flow control valve 11 is electrically connected with the master control system 1.

The invention also provides a pressure control method for the micro liquid outlet, which comprises the following steps:

s1, setting the ratio of the pressure of the upper flow channel 7 to the pressure of the lower flow channel 8 in the master control system 1, and recording the set value as c;

s2, the general control system 1 controls the pressure control unit 5 to provide positive pressure to the liquid reservoir 2, so that the liquid in the liquid reservoir 2 flows to the upper flow passage 7, the liquid flow passage inside the extrusion unit 3, the lower flow passage 8 and the nozzle 4;

s3, the overall control system 1 controls the extrusion control unit 6 to provide positive pressure to the extrusion unit 3, so as to extrude the liquid in the liquid channel of the extrusion unit 3 to the nozzle 4, and the liquid in the nozzle 4 flows out from the lower end of the nozzle 4 to the workpiece, in step S3, when the extrusion control unit 6 provides positive pressure to the extrusion unit 3, most of the liquid flows to the liquid storage 2 along the upper flow channel 7, and only a trace amount of liquid flows out from the nozzle 4 along the lower flow channel 8. When the extrusion unit 3 is deformed by extrusion force, the liquid in the extrusion unit 3 is pushed to flow along the upper flow passage 7 and the lower flow passage 8, most of the liquid flows along the upper flow passage 7, and only a very small amount of liquid flows out along the lower flow passage 8, so that the liquid outlet of the small amount of liquid is realized conveniently;

s4, in the liquid outlet process of the nozzle 4, the upper runner pressure sensor 9 detects the pressure of the upper runner 7 in real time, the detected value is recorded as a1, the detected value a1 is transmitted to the master control system 1, meanwhile, the lower runner pressure sensor 10 detects the pressure of the lower runner 8 in real time, the detected value is recorded as b1, the b1 is transmitted to the master control system 1, and in the step S4, the master control system 1 carries out acquisition value filtering processing on the acquired a1 and b1 data to eliminate the acquisition value with large error. The error of the pressure control of the upper flow passage 7 caused by the acquisition value with larger error is avoided;

s5, the general control system 1 calculates a value a1/b1 as d, and calculates the difference between d and c by optimizing a PID control algorithm, so that the actuator is controlled to adjust the pressure of the upper flow channel 7, and the ratio of the pressure of the upper flow channel 7 to the pressure of the lower flow channel 8 is c.

In step S1, the value of c is set to 1:10 to 1: 1000. When the liquid output of the nozzle 4 is controlled, the pressure of the upper flow passage 7 and the lower flow passage 8 is controlled, so that the resistance ratio of the liquid in the upper flow passage 7 and the liquid in the lower flow passage 8 is controlled, the resistance of the liquid in the upper flow passage 7 is far smaller than that of the lower flow passage 8, therefore, when the extrusion control unit 6 extrudes the extrusion unit 3, a larger part of the liquid in the liquid flow passage in the extrusion unit 3 flows to the liquid storage 2 along the upper flow passage 7, only a small part flows to the nozzle 4 along the lower flow passage 8, and the amount of the liquid in the liquid flow passage in the extrusion unit 3 flowing to the upper flow passage 7 and the lower flow passage 8 can be changed by adjusting the set value of c, so that the liquid output of the nozzle 4 can be adjusted conveniently, compared with the method of adjusting the liquid output of the nozzle 4 by adjusting the deformation amount of the liquid flow passage in the extrusion unit 3, the adjustment mode is simple and convenient, and the pressure of the upper flow passage 7 and the lower flow passage 8 can be adjusted by the upper flow passage pressure sensor 9 and the lower flow sensor 10 The force is detected, thereby improving the uniformity of the liquid outlet amount of the nozzle 4 and improving the liquid outlet stability of the nozzle 4.

Step S5 includes:

s51, the master control system 1 calculates the value d-c, the value d-c is recorded as delta e, the master control system 1 judges the size relation between delta e and 0, if delta e is larger than 0, the master control system 1 controls the flow control valve 11, the flow control valve 11 increases the flow of the upper flow channel 7, the pressure of the upper flow channel 7 is reduced, and the step S4 is continuously executed;

s52, the master control system 1 calculates the value d-c, the value d-c is recorded as delta e, the master control system 1 judges the size relation between delta e and 0, if the delta e is smaller than 0, the master control system 1 controls the flow control valve 11, the flow control valve 11 reduces the flow of the upper flow channel 7, the pressure of the upper flow channel 7 is increased, and the step S4 is continuously executed;

s53, the master control system 1 calculates the value of d-c and records the value as delta e, the master control system 1 judges the size relation between delta e and 0, and if delta e is equal to 0, the step S4 is continuously executed.

The working principle of the invention and the corresponding beneficial effects are that the pressure of the upper flow passage 7 is detected in real time by the upper flow passage pressure sensor 9, when the liquid level in the liquid storage 2 changes, the pressure of the upper flow passage 7 changes, the pressure sensors 9 and 10 transmit the detected pressure values to the master control system 1, the master control system 1 calculates the deviation between the pressure ratio of the upper flow passage 7 and the lower flow passage 8 and a set value, and controls the execution element to regulate the pressure of the upper flow passage 7 by a PID control algorithm, so that the pressure ratio of the upper flow passage and the lower flow passage 8 is stabilized at the set value, the liquid outlet quantity of liquid drops extruded from the nozzle 4 is uniform, the phenomena of leakage and large droplet are avoided, and the liquid outlet quality is improved;

and when controlling the liquid output of the nozzle 4, the pressure of the upper flow passage 7 and the lower flow passage 8 is controlled, so as to control the resistance ratio of the liquid in the upper flow passage 7 and the liquid in the lower flow passage 8, the resistance of the liquid in the upper flow passage 7 is far smaller than the resistance of the liquid in the lower flow passage 8, therefore, when the extrusion control unit 6 extrudes the extrusion unit 3, a larger part of the liquid in the liquid flow passage in the extrusion unit 3 flows to the liquid storage 2 along the upper flow passage 7, only a small part flows to the nozzle 4 along the lower flow passage 8, the amount of the liquid in the liquid flow passage in the extrusion unit 3 flowing to the upper flow passage 7 and the lower flow passage 8 can be changed by adjusting the set value of c, thereby the liquid output of the nozzle 4 can be adjusted conveniently, compared with the liquid output of the nozzle 4 adjusted by adjusting the deformation amount of the liquid flow passage in the extrusion unit 3, the adjustment mode is simple and convenient, and the upper flow passage 7 and the lower flow passage 8 can be adjusted by the upper flow passage pressure sensor 9 and the lower flow pressure sensor 10 The pressure of the liquid is detected, so that the uniformity of the liquid outlet amount of the nozzle 4 is improved, and the stability of the liquid outlet of the nozzle 4 is improved.

Example 2: referring to fig. 4 and 5, the difference from embodiment 1 is that the actuator in the pressure control device for a minute amount of liquid-out is a pressure control unit 5.

The difference between the method for controlling the pressure of the trace amount of liquid out and the method for controlling the pressure of the trace amount of liquid out in embodiment 1 is that step S5 includes:

s51', the master control system 1 calculates the value d-c, which is recorded as delta e, the master control system 1 judges the size relationship between delta e and 0, if delta e is larger than 0, the master control system 1 controls the pressure control unit 5, the pressure control unit 5 reduces the output pressure of the liquid storage 2, so that the pressure of the upper flow passage 7 is reduced, and the step S4 is continuously executed;

s52', the master control system 1 calculates the value d-c, which is recorded as delta e, the master control system 1 judges the size relationship between delta e and 0, if delta e is smaller than 0, the master control system 1 controls the pressure control unit 5, the pressure control unit 5 increases the output pressure of the liquid storage 2, so that the pressure of the upper flow passage 7 is increased, and the step S4 is continuously executed;

s53', the master control system 1 calculates the value of d-c, and records the value as delta e, the master control system 1 judges the size relationship between delta e and 0, if delta e is equal to 0, the step S4 is continuously executed.

Compared with the flow control valve 11 as the actuator, the flow control valve 11 does not need to be additionally arranged on the upper flow passage 7, so that the structure of the whole pressure control system of the upper flow passage 7 and the lower flow passage 8 is simplified, and the cost of the pressure control system is reduced.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.