Automatic flow control method and device

Abstract

The automatic flow control device structurally comprises a valve rod and a valve rod protective sleeve, a sliding way inner cavity matched with the valve rod is formed in the middle of the valve rod protective sleeve, and a sealing part and a sealing cavity are sequentially formed between the sliding way inner cavity and the valve rod. When the tail part of the valve rod slides forwards or backwards along the inner cavity of the slide way under the action of the linear driving device, the gap between the air outlet and the air inlet is linearly reduced or increased, so that the passing flow is linearly reduced or increased; the specific control method comprises the steps that the control module compares current displacement information, detected by the linear encoder, of the valve rod with an input displacement instruction, the linear driving device is controlled to rotate forwards or reversely according to the comparison result, and the valve rod is driven to slide forwards or backwards to the input displacement position in the valve rod sheath; and the gap between the air outlet and the air inlet is dynamically and linearly changed, so that the aim of linearly adjusting the flow is fulfilled, and high-precision flow control is realized.

Description

Technical Field

[0001] The invention relates to the field of instrument manufacturing and flow control, and in particular to an automatic flow control method and a device thereof. Background Art

[0002] In the current instrumentation industry, in order to achieve flow control, adjustable rotor flowmeters or proportional solenoid valves are generally used. Adjustable rotor flowmeters require manual flow adjustment and cannot achieve automatic control. During use, the flow rate will also change with the change of pressure, and the flow rate cannot be stably controlled. In addition, there are disadvantages such as complex assembly process, high cost and high maintenance. Although proportional solenoid valves have higher control accuracy and can automatically control the flow rate, they also have many restrictions in use, such as the pressure cannot be too high, they are not corrosion-resistant, and they are easy to clog, so the maintenance frequency of proportional solenoid valves is high, and the price of proportional solenoid valves on the market is high. Summary of the invention

[0003] The purpose of the present invention is to provide an automatic flow control method and device thereof, which controls the operation of a linear drive device through a control module to drive the valve stem to slide linearly back and forth in the valve stem sleeve according to a displacement instruction. When the valve stem slides to the front end of the valve stem sleeve, the gap between the air outlet and the air inlet increases linearly, causing the flow rate to increase linearly, and vice versa, it decreases linearly, thereby achieving high-precision flow control based on a stepper motor.

[0004] In order to achieve the above technical objectives, the present invention is implemented through the following technical solutions:

[0005] A flow automatic control method, the control steps are as follows:

[0006] S1. The user transmits the instruction to the control module;

[0007] S2. The control module compares the current displacement information of the valve stem detected by the linear encoder with the input displacement command;

[0008] S3. When the input displacement is greater than the current displacement, the control module controls the linear drive device to rotate forward, drives the valve stem to slide forward in the valve stem sleeve to the input displacement, so that the gap between the air outlet and the air inlet is linearly reduced; when the input displacement is less than the current displacement, the control module controls the linear drive device to reverse, drives the valve stem to slide backward in the valve stem sleeve to the input displacement, so that the gap between the air outlet and the air inlet is linearly increased; when the input displacement is equal to the current displacement, the control module controls the linear drive device not to move;

[0009] S4. During the process of driving the valve stem to slide in the valve stem sleeve, the linear encoder transmits the displacement information to the control module in real time.

[0010] In this solution, the control module compares the current displacement information of the valve stem detected by the linear encoder with the input displacement instruction, controls the linear drive device to rotate forward or reverse according to the comparison result, and drives the valve stem to slide forward or backward in the valve stem sleeve to the input displacement position, so that the gap between the air outlet and the air inlet presents a dynamic linear change, thereby achieving the purpose of linearly adjusting the flow rate and realizing high-precision flow control.

[0011] As a further technical solution of the automatic flow control method, after the user transmits the displacement instruction to the control module, the control module calculates the distance between the current displacement information of the valve stem detected by the linear encoder and the input displacement. When the distance calculated by the control module is greater than the total stroke of the valve stem, the opening of the air outlet is deemed to be fully open or fully closed.

[0012] In this solution, the valve stem displacement stroke required for the outlet to go from closed to fully open is the total valve stem stroke. When the distance calculated by the control module is greater than the total valve stem stroke, the outlet will be automatically fully opened or closed to avoid damage to the valve stem due to continuous movement during abutment, and to make the instrument more intelligent and automated.

[0013] As a further technical solution of the automatic flow control method, the tail of the valve stem and the inner cavity of the slideway of the valve stem sleeve form a sealed cavity, and the air inlet is arranged at the tail of the valve stem and located in the sealed cavity.

[0014] In this solution, the volume of the sealing chamber will change dynamically with the movement of the valve stem, and the air inlet is connected to the sealing chamber. When the valve stem slides forward or backward in the valve stem sleeve to the input displacement, the gas in the sealing chamber can flow out through the gap between the valve stem and the air outlet. By further simplifying the structure, low-cost automatic flow control can be achieved.

[0015] As a further technical solution of the automatic flow control method, the tail end of the valve stem is a conical end with a linearly decreasing diameter, and the maximum diameter of the conical end can fit tightly with the air outlet.

[0016] In this solution, the tail end of the valve stem is tapered, and the outer diameter of the tapered shape decreases linearly in the direction of the air outlet, so that the opening of the air outlet changes linearly when the tail end of the valve stem and the air outlet move relative to each other.

[0017] A device using any one of the above technical solutions for automatic flow control method comprises:

[0018] A valve stem, one end of which is connected to the output end of a linear drive device, and the linear drive device controls the valve stem to move forward or backward linearly after receiving a displacement instruction from a control module;

[0019] A valve stem sheath, wherein a slideway inner cavity matching the valve stem is provided in the middle of the valve stem sheath;

[0020] Among them, a sealing part and a sealing cavity are formed in sequence between the inner cavity of the slide and the valve stem, the sealing cavity is provided with an air outlet in the displacement direction of the valve stem, and the tail of the valve stem is provided with an air inlet, the air inlet is connected to the sealing cavity, and when the tail of the valve stem slides forward or backward along the inner cavity of the slide under the action of the linear drive device, the gap between the air outlet and the air inlet will linearly decrease or increase, so that the flow rate will linearly decrease or increase.

[0021] As a further technical solution of the automatic flow control device, the tail end of the valve stem is a conical end with a linearly decreasing diameter, and the maximum diameter of the conical end can fit tightly with the air outlet.

[0022] In this solution, the diameter of the valve stem and the taper of the tail end can be adjusted according to the size of the controlled flow rate. Generally, the larger the valve stem diameter is, the larger the flow range allowed is.

[0023] As a further technical solution of the automatic flow control device, the sealing part includes at least one sealing ring, which is sleeved on the valve stem and forms a sealing structure between the inner cavity of the slideway and the valve stem.

[0024] In this solution, the outer side wall of the valve stem is provided with a radial sealing ring to isolate the sealing cavity from the outside and avoid air leakage.

[0025] As a further technical solution to the automatic flow control device, a limiting groove is provided in communication with the front end of the inner cavity of the slideway, the inner cavity diameter of the limiting groove is larger than the diameter of the inner cavity of the slideway, and the valve stem is provided with a limiting structure matching the limiting groove, which is used to protect the valve stem and prevent the valve stem from being damaged due to continuous movement when abutting.

[0026] As a further technical solution to the automatic flow control device, the distance from the limiting structure to the bottom wall of the limiting groove is equal to the displacement stroke required by the valve stem to make the air outlet go from closed to fully open, which is further used to protect the valve stem.

[0027] As a further technical solution of the automatic flow control device, the outer side wall of the valve stem sheath is provided with at least one sealing ring groove, and the sealing ring groove can form a sealing structure with other interface equipment.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. The present invention is small in size and easy to integrate;

[0030] 2. The present invention can linearly adjust the flow rate;

[0031] 3. The present invention has a simple structure, low cost and extremely high pressure resistance;

[0032] 4. The present invention is based on a stepper motor and can achieve high-precision flow control;

[0033] 5. The present invention can select the materials of the valve stem and the sheath according to different use environments, and can achieve higher corrosion resistance;

[0034] 6. The present invention can realize low-cost automatic flow control in instruments and related flow control occasions, making the instruments intelligent and automated. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0036] Figure 1 It is a schematic diagram of the structural analysis of the present invention;

[0037] Figure 2 It is a schematic diagram of the overall structure of the present invention.

[0038] Marks and corresponding parts names in the attached drawings:

[0039] 1- linear drive device; 2- valve stem; 3- valve stem sleeve; 21- sealing ring; 22- limiting structure; 31- limiting groove; 32- sealing ring groove; 33- air inlet; 34- air outlet. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0041] Example 1

[0042] This embodiment 1 provides an automatic flow control device, such as Figure 1-Figure 2 As shown, it includes a valve stem 2 and a valve stem sheath 3, one end of the valve stem 2 is connected to the output end of the linear drive device 1, and the linear drive device 1 controls the valve stem 1 to move forward or backward linearly after receiving the displacement instruction of the control module; the middle part of the valve stem sheath 3 is provided with a slideway inner cavity matching the valve stem 1;

[0043] Among them, the linear drive device 1 can be a linear stepping motor, or a linear driver, a pneumatic cylinder, a hydraulic motor, a worm gear transmission and a trapezoidal screw transmission, etc. A sealing portion and a sealing cavity are formed in sequence between the inner cavity of the slide and the valve stem 2. The sealing cavity is provided with an air outlet 34 in the displacement direction of the valve stem 2, and the air inlet 33 is connected to the sealing cavity. When the tail of the valve stem 2 slides forward or backward along the inner cavity of the slide under the action of the linear drive device 1, the gap between the air outlet 34 and the air inlet 33 will linearly decrease or increase, so that the flow rate will be linearly reduced or increased.

[0044] Specifically, see Figure 2 As shown, the end face of the output end of the linear drive device 1 is connected to the valve stem sleeve 3, and a slideway cavity matching the valve stem 1 is arranged in the middle of the valve stem sleeve 3. One end of the valve stem 2 is connected to the output end of the linear drive device 1, and the other end of the valve stem 2 is a free end and is slidably inserted into the slideway cavity of the valve stem sleeve 3. A sealing portion is arranged on the outer wall surface of one side end of the valve stem 2 close to the linear drive device 1, and the sealing portion includes at least one sealing ring 21, and the sealing rings 21 are all sleeved on the valve stem 2. The sealing ring 21 forms a sealing structure between the slideway cavity and the valve stem 2. In this embodiment, according to the pressure of the introduced gas, the sealing portion includes two sealing rings 21, and the two sealing rings 21 are sleeved on the valve stem 2 at intervals. In actual use, the number of sealing rings 21 can be adjusted according to the size of the introduced gas pressure.

[0045] Secondly, a sealed cavity is formed between the outer wall surface of one side end of the valve stem 2 away from the linear drive device 1, the inner wall surface of the slideway and the sealing part. The required pressurized gas is introduced into the sealed cavity through the air inlet 33. At the same time, the sealed cavity is provided with an air outlet 34 in the displacement direction of the valve stem 2. The air outlet 34 is a cylindrical through hole, and the diameter of the air outlet 34 is smaller than the diameter of the sealed cavity.

[0046] Finally, the tail end of the valve stem 2 is a conical end with a linearly decreasing diameter. The diameter of the valve stem 2 and the taper of the tail end can be adjusted according to the size of the controlled flow rate. Generally, the larger the diameter of the valve stem 2, the larger the flow range allowed to pass through, and the maximum diameter of the conical end can fit tightly with the air outlet 34 to form an end face seal. When the valve stem 2 slides to the front end of the valve stem sheath 3, the air outlet 34 is supported by the tail end of the valve stem 2, so that the flow of the air outlet 34 is zero; when the tail end of the valve stem 2 is completely separated from the air outlet 34, the flow of the air outlet 34 reaches a maximum.

[0047] Example 2

[0048] Since in Example 1, the valve stem displacement stroke required for the outlet 34 to be completely opened from closed to fully opened is the total valve stem stroke, when the distance calculated by the control module is greater than the total valve stem stroke, the valve stem 2 may be damaged by continuous movement during abutment. To avoid this phenomenon, this Example 2 provides another automatic flow control device, such as Figure 1-Figure 2 As shown, it includes a valve stem 2 and a valve stem sleeve 3, one end of the valve stem 2 is connected to the output end of the linear drive device 1, and the linear drive device 1 controls the valve stem 1 to move forward or backward linearly after receiving the displacement instruction of the control module; a slideway cavity matching the valve stem 1 is arranged in the middle of the valve stem sleeve 3; a sealing part and a sealing cavity are formed in sequence between the slideway cavity and the valve stem 2, and in order to simplify the structure and improve the integration, the sealing cavity is provided with an air outlet 34 in the displacement direction of the valve stem 2, the interior of the valve stem 2 is hollow and an air inlet 33 is arranged at the tail of the valve stem 2, the air inlet 33 is connected to the sealing cavity, and when the tail of the valve stem 2 slides forward or backward along the slideway cavity under the action of the linear drive device 1, the gap between the air outlet 34 and the air inlet 33 will be linearly reduced or increased, so that the flow rate is linearly reduced or increased.

[0049] Specifically, see Figure 2 As shown, in order to make the flow control more precise, the linear drive device 1 of this embodiment is a linear stepper motor, and the end face of the output end of the linear stepper motor is connected to the valve stem sleeve 3. A slideway cavity matching the valve stem 2 is arranged in the middle of the valve stem sleeve 3, one end of the valve stem 2 is connected to the output end of the linear stepper motor, and the other end of the valve stem 2 is a free end and is slidably penetrated in the slideway cavity of the valve stem sleeve 3, and a limiting groove 31 is arranged on the side of the slideway cavity close to the linear stepper motor. The inner cavity diameter of the limiting groove 31 is larger than the diameter of the slideway cavity, and the valve stem 2 is provided with a limiting structure 22 matching the limiting groove 31, and the limiting structure 22 is a protrusion extending radially along the valve stem 2, and the distance from the limiting structure 22 to the bottom wall of the limiting groove 31 is equal to the displacement stroke required for the valve stem 2 to make the air outlet 34 from closed to fully open. When the valve stem 2 slides to the front end of the valve stem sleeve 3, the valve stem 2 is limited from continuing to move, which is used to protect the valve stem.

[0050] At the same time, a sealing portion is provided on the outer wall surface of one side end of the valve stem 2 close to the linear stepper motor, and the sealing portion includes at least one sealing ring 21, and the sealing ring 21 is sleeved on the valve stem 2. The sealing ring 21 forms a sealing structure between the inner cavity of the slide and the valve stem 2. In this embodiment, according to the pressure of the incoming gas, the sealing portion includes two sealing rings 21, and the two sealing rings 21 are sleeved on the valve stem 2 at intervals. In actual use, the number of sealing rings 21 can be adjusted according to the size of the incoming gas pressure.

[0051] Secondly, a sealed cavity is formed between the outer wall surface of one side end of the valve stem 2 away from the linear stepper motor, the inner wall surface of the slideway and the sealing part. The required pressurized gas is introduced into the sealed cavity through the air inlet 33. At the same time, the sealed cavity is provided with an air outlet 34 in the displacement direction of the valve stem 2. The air outlet 34 is a cylindrical through hole, and the diameter of the air outlet 34 is smaller than the diameter of the sealed cavity.

[0052] Finally, the tail end of the valve stem 2 is a conical end with a linearly decreasing diameter. The diameter of the valve stem 2 and the taper of the tail end can be adjusted according to the size of the controlled flow rate. Generally, the larger the diameter of the valve stem 2, the larger the flow range allowed to pass through, and the maximum diameter of the conical end can fit tightly with the air outlet 34 to form an end face seal. When the valve stem 2 slides to the front end of the valve stem sheath 3, the air outlet 34 is supported by the tail end of the valve stem 2, so that the flow of the air outlet 34 is zero; when the tail end of the valve stem 2 is completely separated from the air outlet 34, the flow of the air outlet 34 reaches a maximum.

[0053] In this embodiment, the material of the valve stem 2 and the valve stem sheath 3 can be customized according to the usage scenario to achieve higher corrosion resistance, and the outer wall of the valve stem sheath 3 is provided with at least one sealing ring groove 32, which can form a sealing structure with other interface devices. The specific number can be selected according to the sealing strength.

[0054] Example 3

[0055] This embodiment 3 is a flow automatic control method for the device described in embodiment 1 or 2, and the control steps are as follows:

[0056] S1. The user transmits the instruction to the control module;

[0057] S2. The control module compares the current displacement information of the valve stem 2 detected by the linear encoder with the input displacement command;

[0058] S3. When the input displacement is greater than the current displacement, the control module controls the linear drive device 1 to rotate forward, driving the valve stem 2 to slide forward in the valve stem sheath 3 to the input displacement, that is, the tail end of the valve stem 2 moves forward along the air outlet 34, so that the gap between the air outlet 34 and the air inlet 33 is linearly reduced; when the input displacement is less than the current displacement, the control module controls the linear drive device 1 to reverse, driving the valve stem 2 to slide backward in the valve stem sheath 3 to the input displacement, that is, the tail end of the valve stem 2 withdraws backward along the air outlet 34, so that the gap between the air outlet 34 and the air inlet 33 is linearly increased; when the input displacement is equal to the current displacement, the control module controls the linear drive device not to move;

[0059] S4. In the process of driving the valve stem 2 to slide in the valve stem sleeve 3, the linear encoder transmits the displacement information to the control module in real time, and the linear encoder calculates the distance between the current displacement information of the valve stem 22 and the input displacement in real time. When the distance calculated by the control module is greater than the total stroke of the valve stem, the opening of the air outlet 34 is deemed to be fully open or fully closed, and the valve stem 2 will automatically execute the steps of fully opening or fully closing the air outlet 34; in some embodiments, when the distance calculated by the control module is greater than half of the total stroke of the valve stem, the control module will issue an instruction to control the linear drive device 1 to rotate in a manner that the moving speed of the first half is greater than the moving speed of the second half; when the distance calculated by the control module is less than half of the total stroke of the valve stem, the control module will issue an instruction to control the linear drive device 1 to rotate at a lower speed. This method can achieve higher-precision flow control.

[0060] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for automatic flow control, characterized in that: The control steps are as follows: S1. The user transmits the instruction to the control module; S2. The control module compares the current displacement information of the valve stem (2) detected by the linear encoder with the input displacement command; S3. When the input displacement is greater than the current displacement, the control module controls the linear drive device to rotate forward, drives the valve stem (2) to slide forward in the valve stem sleeve (3) to the input displacement, so that the gap between the air outlet (34) and the air inlet (33) is linearly reduced; when the input displacement is less than the current displacement, the control module controls the linear drive device to rotate reversely, drives the valve stem (2) to slide backward in the valve stem sleeve (3) to the input displacement, so that the gap between the air outlet (34) and the air inlet (33) is linearly increased; when the input displacement is equal to the current displacement, the control module controls the linear drive device not to operate; S4. During the process of driving the valve stem (2) to slide in the valve stem sleeve (3), the linear encoder transmits the displacement information to the control module in real time.

2. The automatic flow control method according to claim 1, characterized in that: After the user transmits the displacement instruction to the control module, the control module calculates the distance between the current displacement information of the valve stem (2) detected by the linear encoder and the input displacement. When the distance calculated by the control module is greater than the total stroke of the valve stem (2), the opening of the air outlet (34) is deemed to be fully open or fully closed.

3. The automatic flow control method according to claim 1, characterized in that: The tail of the valve stem (2) and the inner cavity of the slideway of the valve stem sheath (3) form a sealed cavity, and the air inlet (33) is arranged at the tail of the valve stem (2) and is located in the sealed cavity.

4. A flow automatic control method according to claim 3, characterized in that: The tail end of the valve stem (2) is a conical end with a linearly decreasing diameter, and the maximum diameter of the conical end can fit tightly with the air outlet (34).

5. A flow automatic control device, using a flow automatic control method as claimed in any one of claims 1 to 4, characterized in that: include: A valve stem (2), one end of the valve stem (2) being connected to an output end of a linear drive device, and the linear drive device controls the valve stem (2) to move forward or backward linearly after receiving a displacement instruction from a control module; A valve stem sheath (3), wherein a slideway inner cavity matching the valve stem (2) is provided in the middle of the valve stem sheath (3); A sealing portion and a sealing cavity are formed in sequence between the inner cavity of the slide and the valve stem (2); the sealing cavity is provided with an air outlet (34) in the displacement direction of the valve stem (2); the tail of the valve stem (2) is provided with an air inlet (33); the air inlet (33) is connected to the sealing cavity; and when the tail of the valve stem (2) slides forward or backward along the inner cavity of the slide under the action of the linear drive device, the gap between the air outlet (34) and the air inlet (33) will be linearly reduced or increased, so that the flow rate will be linearly reduced or increased.

6. The automatic flow control device according to claim 5, characterized in that: The tail end of the valve stem (2) is a conical end with a linearly decreasing diameter, and the maximum diameter of the conical end can fit tightly with the air outlet (34).

7. The automatic flow control device according to claim 5, characterized in that: The sealing portion comprises at least one sealing ring (21), and the sealing ring (21) is sleeved on the valve stem (2). The sealing ring (21) forms a sealing structure between the inner cavity of the slideway and the valve stem (2).

8. The automatic flow control device according to claim 5, characterized in that: A limiting groove (31) is provided at the front end of the inner cavity of the slideway, the inner cavity diameter of the limiting groove (31) is larger than the diameter of the inner cavity of the slideway, and the valve stem (2) is provided with a limiting structure (22) matching the limiting groove (31).

9. The automatic flow control device according to claim 8, characterized in that: The distance between the limiting structure (22) and the bottom wall of the limiting groove (31) is equal to the displacement stroke required by the valve stem (2) to make the air outlet (34) go from closed to fully open.

10. The automatic flow control device according to claim 5, characterized in that: The outer side wall of the valve stem protective sleeve (3) is provided with at least one sealing ring groove (32), and the sealing ring groove (32) can form a sealing structure with other interface equipment.

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