Electric proportional valve

Abstract

The utility model provides an electric proportional valve which comprises a valve body and a control unit, and the valve body is provided with an air inlet pipeline connected with an air source, an air outlet pipeline connected with an air load and an exhaust pipeline communicated with the external environment. The control unit adjusts the proportion of the gas amount entering the gas outlet pipeline and the gas exhaust pipeline from the gas inlet pipeline based on closed-loop feedback control; a gas release pipeline is further arranged in the valve body, and part of gas in the gas outlet pipeline can be discharged to the external environment in the mode that the gas amount participating in closed-loop feedback control in the gas outlet pipeline is reduced. According to the electric proportional valve, the air pressure oscillation phenomenon of the air outlet pipeline under the low-flow and high-frequency switching air using demand scene can be remarkably reduced, and rapid, accurate and stable tracking of the target air pressure is achieved.

Description

Technical Field

[0001] This application relates to the field of valve technology, and in particular to an electro-proportional valve. Background Technology

[0002] In automated control systems, especially pneumatic control systems, electro-proportional valves are connected between a high-pressure air source and a pneumatic load. They control the flow of air to the pneumatic load through feedback closed-loop control. Currently, the closed-loop feedback control used in electro-proportional valves typically involves a proportional controller setting a PID adjustment value based on the difference between the measured and target air pressures. This value is then converted into a PWM or other control signal to adjust the proportion of air output from the air source to the outlet pipe (connected to the pneumatic load) and the exhaust pipe (connected to the external environment).

[0003] Electronic proportional pressure control devices can immediately provide the required output pressure and maintain it stable for a specified time, while continuously adjusting the output according to dynamic conditions to maintain pressure stability. However, in dynamic and continuous flow processes, even within the stability tolerance range, instability peaks may occur. These fluctuations may arise from unexpected back pressure, increased load gas demand, sudden changes in inlet pressure, or significant temperature changes. A proportional valve needs to react quickly to stabilize these fluctuations.

[0004] The two main factors affecting control accuracy are stability and filling time (the time it takes for the air pressure to return to the set value after it has dropped due to load air consumption, inlet pressure, pipeline limitations, etc.). Generally, the valve nozzle size of the internal valve needs to be designed according to the air consumption requirements of the load, and the proportional controller needs to set the PID value within a reasonable range in order to accurately and quickly achieve the target air pressure output.

[0005] However, in actual use, there is a situation where the valve flow rate determined by the load air volume cannot be reconciled with the PID value setting range that satisfies both accuracy and speed: due to the limitations of the mechanical structure and air chamber volume within the valve body, the PID value adjustment setting can only be effective within a relatively small window. If the air volume demand is large, it will also cause airflow instability in the measurement air path. Once the threshold range is exceeded, the oscillation problem cannot be solved by adjusting the PID parameters. Although reducing the orifice diameter of the measurement air path can stabilize the measurement airflow and avoid system oscillation, it will inevitably lead to a longer air pressure measurement time, making it impossible to achieve high-speed regulation of the outlet air pressure.

[0006] Therefore, it is necessary to improve the structure and control method of the existing electro-proportional valve in order to achieve high-speed, precise and stable control of the output air volume. Utility Model Content

[0007] This application provides an electro-proportional valve through embodiments to solve the problem of inaccurate flow control caused by oscillation circuits due to the proportional valve being too small or the valve flow being too large in the prior art.

[0008] The electro-proportional valve includes a valve body and a control unit. The valve body has an inlet pipe connected to a gas source, an outlet pipe connected to a gas load, and an exhaust pipe connected to the external environment. The control unit adjusts the ratio of the gas volume entering the outlet pipe and the exhaust pipe from the inlet pipe based on closed-loop feedback control.

[0009] The valve body is also provided with a venting pipe, which can discharge a portion of the gas in the venting pipe to the external environment by reducing the amount of gas participating in the closed-loop feedback control in the venting pipe.

[0010] Preferably, the maximum airflow rate of the venting pipe is much smaller than the maximum airflow rate of the outlet pipe and / or the exhaust pipe.

[0011] Furthermore, the venting line discharges a portion of the gas in the outlet line to the external environment before the gas pressure in the outlet line is measured, thereby reducing the amount of gas participating in the closed-loop feedback control in the outlet line.

[0012] Furthermore, the control unit adjusts the proportion of air entering the outlet pipe and the exhaust pipe from the inlet pipe by comparing the difference between the air pressure in the air pressure measuring pipeline and the target air pressure based on closed-loop feedback control, wherein the air pressure measuring pipeline is connected to the outlet pipe.

[0013] The location where the vent pipe connects to the outlet pipe is closer to the inlet pipe than the location where the pressure measuring pipe connects to the outlet pipe.

[0014] Preferably, the number of vent pipes is greater than or equal to 2.

[0015] Preferably, the electro-proportional valve further includes an on / off valve for switching the connection state of at least one of the vent lines with the external environment.

[0016] Preferably, the electro-proportional valve further includes a flow regulating valve for regulating the flow rate of gas discharged from at least one of the vent lines to the external environment.

[0017] Preferably, one end of the vent pipe is connected to the outlet pipe and the other end is connected to the exhaust pipe, and the vent pipe can discharge a portion of the gas in the air pipe to the external environment through the exhaust pipe when the passage between the exhaust pipe and the inlet pipe is completely closed.

[0018] Preferably, the electro-proportional valve further includes a buffer cavity disposed inside the valve body and connected to at least one of the vent lines inside or outside the valve body.

[0019] Preferably, the volume of the buffer cavity is much larger than the volume of the vent pipe.

[0020] Preferably, the valve body is provided with an air inlet, an air outlet, and an exhaust outlet arranged circumferentially thereon. The air inlet direction of the air inlet pipe is parallel to the air outlet direction of the air outlet pipe flowing towards the load through the air outlet. The exhaust direction of the exhaust pipe flowing towards the external environment through the exhaust outlet is perpendicular to the air inlet direction of the air inlet pipe.

[0021] A vent pipe is provided on the other side between the air inlet and the air outlet. One end of the vent pipe is connected to the external environment, and the other end is connected to the air outlet pipe.

[0022] Preferably, the venting pipe is connected to the outlet through the first partition, or the venting pipe is connected through the adjacent sidewall between the outlet and the exhaust port, or the venting pipe is connected through the adjacent sidewall between the first partition and the exhaust port, and is located between the air pressure measuring pipe of the outlet pipe and the first partition, and the airflow after the air pressure is adjusted by the venting pipe enters the air pressure measuring pipe.

[0023] Preferably, the valve body houses a valve core drive assembly, and the lower part of the valve core drive assembly is housed within the first cavity;

[0024] The valve core drive assembly includes a valve column, a diaphragm connected to the top of the valve column, a convex ring sleeved on the valve column, and a first valve core and a second valve core located at both ends of the valve column, with the second valve core located below the diaphragm. The convex ring limits the position of the second valve core. The bottom end of the valve column passes through the intermediate valve body and extends to the bottom of the main valve body. The second piston limit of the second valve core is located between the lower end face of the chamber of the intermediate valve body and the convex ring. The two cooperate to form an exhaust valve port. A second spring is provided inside the second valve core.

[0025] The first valve core is disposed between the main valve body and the bottom cover as an intake valve core. The first piston limit of the first valve core is located at the lower end face of the bottom of the main valve body. The two cooperate to form an intake valve port. The first valve core is provided with a first spring that drives the first piston to close the intake valve port.

[0026] An embodiment of this application provides an electro-proportional valve that, by setting a separate venting pipe between the outlet pipe and the external environment, can discharge a portion of the gas in the outlet pipe to the external environment by reducing the amount of gas participating in closed-loop feedback control. Without changing the diameter of the pressure measurement pipe, and to avoid prolonging the pressure measurement response time, it can significantly reduce the impact and generation of airflow debris when the airflow enters the pressure measurement pipe at low flow rates. This allows the pressure sensor to quickly and accurately obtain the true air pressure value in the outlet pipe and dampen the airflow, thereby significantly reducing the air pressure oscillation phenomenon in the outlet pipe under low flow and high frequency switching gas demand scenarios, and achieving rapid, accurate, and stable tracking of the target air pressure. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of an existing electro-proportional valve.

[0028] Figure 2 for Figure 1 A magnified schematic diagram of a local structure;

[0029] Figure 3 for Figure 1 The diagram shown is a partial enlarged structural schematic of the electro-proportional valve when the intake pipe is closed.

[0030] Figure 4 for Figure 1 The diagram shows a partial structural method of the electro-proportional valve when the inlet pipe, outlet pipe and exhaust pipe are all open at the same time.

[0031] Figure 5 A schematic diagram of air pressure oscillation in the outlet pipeline when performing low-flow output control for an existing electro-proportional valve;

[0032] Figure 6 This is a schematic diagram of the structure of an electro-proportional valve provided according to a specific embodiment of this application;

[0033] Figure 7 This is a partially enlarged schematic diagram of the gas pipeline portion of an electro-proportional valve provided according to a specific embodiment of this application;

[0034] Figure 8 A diagram showing the pressure change in the outlet pipeline when the outlet volume is controlled by the electro-proportional valve provided in a specific embodiment of this application.

[0035] Figure 9 This is a partially enlarged schematic diagram of the gas pipeline portion of an electro-proportional valve provided according to a specific embodiment two of this application;

[0036] Figure 10This is a partially enlarged schematic diagram of the gas pipeline portion of an electro-proportional valve provided according to a specific embodiment three of this application;

[0037] Figure 11 This is a partially enlarged schematic diagram of the gas pipeline portion of an electro-proportional valve provided according to a specific embodiment four of this application;

[0038] Figure 12 This is a partially enlarged schematic diagram of the gas pipeline portion of an electro-proportional valve provided according to a specific embodiment five of this application;

[0039] Figure 13 This is a partially enlarged schematic diagram of the gas pipeline portion of the electro-proportional valve provided according to a specific embodiment six of this application;

[0040] Figure 14 This is a schematic diagram of the overall structure of an electro-proportional valve according to a specific embodiment seven of this application;

[0041] Figure 15 This is an exploded structural diagram of an electro-proportional valve according to a specific embodiment seven of this application;

[0042] Figure 16 This is a cross-sectional schematic diagram of an electro-proportional valve provided according to a specific embodiment seven of this application;

[0043] Figure 17 This is a cross-sectional schematic diagram of an electro-proportional valve provided according to a specific embodiment seven of this application from another direction;

[0044] Figure 18 This is a cross-sectional schematic diagram of an electro-proportional valve provided in a specific embodiment seven of this application, wherein a buffer cavity is provided in another direction.

[0045] Numbers in the diagram

[0046] Electro-proportional valve 1, existing electro-proportional valve 1', valve body 11, air inlet 1.1, air inlet valve port 1.11, exhaust valve 1.12, air outlet 1.2, exhaust port 1.3, vent port 1.4, first diaphragm 110, second diaphragm 119, first valve core 17', second valve core 17'", main valve body 111, bottom cover 112, intermediate valve body 113, pilot seat 114, control unit 12, first control air path 131, second control air path 132, third control air path 133, solenoid valve exhaust air path 134, control Box 14, air supply solenoid valve 141, exhaust solenoid valve 142, upper chamber 151, lower chamber 152, diaphragm 153, one-way valve 154, valve column 16, convex ring 161, first piston 171, second piston 172, spring 18, first spring 181, second spring 182, air inlet pipe 2, air inlet pipe branch 21, air outlet pipe 3, air pressure measuring pipe 31, air outlet pipe branch 32, air pressure sensor 33, exhaust pipe 4, vent pipe 5, opening and closing valve 61, flow regulating valve 62, buffer chamber 7. Detailed Implementation

[0047] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0048] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. For ease of understanding, various components in the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application.

[0049] Furthermore, in order to distinguish different units, the terms "first," "second," etc., are used in this specification. However, these terms are not limited by the order of manufacture and should not be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application.

[0050] The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise expressly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this application.

[0051] To clearly illustrate the improvements made by this application compared to the prior art, the working principle of existing electro-proportional valves and their existing problems are first explained.

[0052] [Existing technology and existing problems]

[0053] Figure 1 A schematic diagram of the structure of an existing electro-proportional valve 1' is shown. Figure 2 right Figure 1 The circle A in the middle is enlarged for reference. Figure 1 and Figure 2 The shape of the electro-proportional valve 1' is generally defined by the valve body 11, which includes the following structural or functional units:

[0054] 1) Gas pipeline structure, including an intake pipeline 2 connected to a gas source (not shown in the figure), an outlet pipeline 3 connected to a gas-using load, and an exhaust pipeline 4 connected to the external environment.

[0055] Generally, a high-pressure gas source is used, and the high-pressure gas output from it flows through an electro-proportional valve 1'. The electro-proportional valve 1' adjusts the gas volume of the outlet pipe 3 and the exhaust pipe 4 according to the target gas pressure, so that the gas pressure in the outlet pipe 3 used to drive the load (such as a cylinder, pressure vessel, or pneumatic component that needs to receive a preset gas pressure at a preset frequency) reaches the target gas pressure as much as possible.

[0056] 2) Control air circuit structure, including first control air circuit 131, second control air circuit 132, third control air circuit 133, solenoid valve exhaust air circuit 134, air supply solenoid valve 141 and exhaust solenoid valve 142.

[0057] One end of the first control air path is connected to the intake pipe branch 21 led out from the intake pipe 2, and the other end is connected to the intake port of the supply solenoid valve 141. The two ends of the second control air path 132 are connected to the outlet of the supply solenoid valve 141 and the inlet of the exhaust solenoid valve 142, respectively. The outlet of the exhaust solenoid valve is connected to the external environment through the solenoid valve exhaust air path 134.

[0058] Furthermore, a third control gas path 133 is led out from the second control gas path 132 for outputting control gas to the upper chamber described later.

[0059] 3) The gas distribution mechanical structure includes an upper chamber 151, a lower chamber 152, a diaphragm 153, a valve column 16, a first piston 171, and a second piston 172.

[0060] The upper chamber 151 and the lower chamber 152 are separated into two non-connected spaces by an elastic diaphragm 153. The upper chamber 151 is connected to the third control air passage 133 to receive control gas output from the self-supply solenoid valve 141. One end of the valve column 16 is formed into a relatively flat sheet structure and is fixedly connected to the diaphragm 153. Its cylindrical body passes through the second piston 172 and abuts or is fixedly connected to the upper end of the first piston 171. The first piston 171 and the second piston are elastically abutted against the opposite sides of each other by springs 18. In addition, a convex ring is provided on the cylindrical body of the valve column 16 on the side of the second piston 172 facing the first piston 171.

[0061] 4) The air pressure measuring air path 31 is led out from the air outlet line 3 and connected to the air pressure sensor 33. Preferably, an air outlet line branch 32 is also led out from the air outlet line 3 and connected to the lower chamber 152. The air outlet line branch 32 can be led out independently from the air outlet line 3, or it can be... Figure 1 As shown, it is led out from the air pressure measurement air path 31.

[0062] 5) Control unit 12, based on closed-loop feedback control, adjusts the ratio of air volume entering the air outlet pipe 3 and the exhaust pipe 4 from the intake pipe 2.

[0063] Specifically, when the electro-proportional valve is connected to the power supply and turned on, the control unit 12 simultaneously receives the target air pressure signal Sig_t and the air pressure measurement signal Sig_m of the outlet pipeline 3 measured and fed back by the air pressure sensor 33. Through closed-loop feedback control known to those skilled in the art, the PID adjustment amount is set according to the difference between the two, and on this basis, the control command Ctr_1 for controlling the opening and closing of the air supply solenoid valve 141 and the control command Ctr_2 for controlling the opening and closing of the exhaust solenoid valve 142 are generated. Generally, both Ctr_1 and Ctr_2 can be in the form of PWM signals.

[0064] Under the control of Ctr_1 and Ctr_2, the supply solenoid valve 141 and exhaust solenoid valve 142 regulate the amount of gas entering the third control solenoid valve 133 from the first control solenoid valve 131 (and the amount of gas discharged to the external environment through the exhaust solenoid valve 134), thereby causing the diaphragm 153 between the upper chamber 151 and the lower chamber 152 to deform with the change in gas volume, driving the valve column 16 to move up and down, and using the first piston 171 and the second piston 172 to regulate the amount of gas flowing through the outlet pipe 3 and the exhaust pipe 4.

[0065] For example, like Figure 2As shown, when the valve column 16 moves downward to the lowest point under the action of the diaphragm 153, the first piston 171 is at the lowest point, the intake pipe 2 and the outlet pipe 3 are connected and the opening diameter is large. The second piston 172 closes the passage between the exhaust pipe 4 and the intake pipe 2 under the action of the spring 18. At this time, most of the gas entering the electro-proportional valve 1' from the intake pipe 2 (except for the part entering the control air circuit, the air pressure measuring pipe 31 and the outlet pipe branch 32) will flow to the load through the outlet pipe 3, causing the air pressure in the outlet pipe 3 to rise rapidly.

[0066] Figure 3 and Figure 4 Enlarged schematic diagram (enlarged area same as above) Figure 2 The following shows two other possible gas distribution states, where the electro-proportional valve 1' is in... Figure 3 In the indicated state, the diaphragm 153 of the valve stem 16 moves upward to its highest point, and the first piston 171 is elastically reset by the spring 18, completely sealing the passage from the intake pipe 2 to the exhaust pipe 3. Simultaneously, the second piston 172 moves upward under the action of the convex ring 161, opening the passage between the exhaust pipe 3 and the exhaust pipe 4 to its maximum. Gas is discharged to the external environment through the exhaust pipe 4, causing a rapid drop in the gas pressure in the exhaust pipe 3. When the electro-proportional valve 1' is in... Figure 4 In the state shown, the passages between the intake pipe 2 and the exhaust pipe 3 and exhaust pipe 4 are all open. Part of the gas entering the electric proportional valve 1' through the intake pipe 2 enters the exhaust pipe to drive the load, while the other part is discharged to the external environment through the exhaust pipe 4.

[0067] Preferably, the control unit 12 can be connected to a computer, tablet computer, or mobile phone to display the above-mentioned signals, control commands, etc., on the display screen of the device in the form of signal info, so as to monitor the working status of the electro-proportional valve.

[0068] Clearly, through the closed-loop feedback control of control unit 12, the electro-proportional valve 1' will continuously... Figures 2 to 4 The system switches between the three displayed states to adjust the ratio of air volume entering the intake pipe 2 into the exhaust pipe 3 and the exhaust pipe 4, so that the air pressure in the exhaust pipe 3 reaches the preset target air pressure.

[0069] In addition, it should be pointed out that, Figure 1The sectional view shown illustrates the working principle of only one existing electro-proportional valve 1'. Other existing electro-proportional valves may have different structures; for example, the control air path, solenoid valve, and control unit 12 can all be integrated into the valve body 11 to achieve device miniaturization; or the first piston 171 and the second piston 172 can be designed to move synchronously with the valve column 16; or only one solenoid valve can be used to control the ratio of gas entering the upper chamber and gas discharged to the external environment, etc. The above structural changes do not affect the working principle, that is: the control unit 12 adjusts the ratio of the amount of gas entering the outlet pipe 3 and the exhaust pipe 4 from the intake pipe 2 based on closed-loop feedback control.

[0070] In the pneumatic control of electro-proportional valves, achieving a balance between response speed and stability according to the specific application requirements of the driven load is a complex task. As mentioned in the background, the two main factors affecting the performance of closed-loop feedback control are stability and fill time. For some application scenarios with low response speed requirements (e.g., load states do not change frequently), the length of fill time is not a key consideration. Therefore, the tolerance for PID regulation is relatively high, meaning that a longer fill time can be used to achieve stable tracking of the target air pressure in the outlet pipeline 3. However, in some scenarios with high requirements for fill time, the situation becomes more complicated.

[0071] For example, in the field of precision dispensing, the gas flow rate required for each dispensing operation is extremely low. After each dispensing action, in order to avoid unnecessary dripping of glue due to the residual air pressure in the glue tank, it is necessary to extract the gas above the glue tank and then quickly restore the air pressure to the target air pressure after the next dispensing action begins. At the same time, in order to improve the efficiency of the dispensing process, it is generally necessary to further shorten the interval between two dispensing actions (at a frequency of 5 times / second or higher). Therefore, the air pressure in the pipeline needs to repeatedly undergo the operation of filling to the target air pressure at a low flow rate -> maintaining stability -> depressurizing -> refilling to the target air pressure within a very short cycle.

[0072] Clearly, simultaneously meeting the requirements of low flow rate, high response speed, and high stability in the above application scenarios becomes extremely challenging. This is because, in these low-flow-rate applications, the downstream load gas volume is typically very small, and correspondingly, the internal volume of the valve is also reduced. When the requirement of rapidly tracking the target gas pressure is needed, ideally, the pressure could be quickly reached through rapid inflation. However, the limited internal volume of the valve will cause compressed air to violently impact the space when the inlet valve opens, resulting in pressure exceeding the set point. Before the pressure stabilizes, the pressure sensor will detect reflected air fragments, prompting the exhaust valve to open and discharge excess pressure from the volume, immediately leading to excessively low pressure. This deviation in pressure detection due to volume limitation will cause the gas pressure in outlet pipeline 3 to fluctuate as follows: Figure 5 The periodic oscillation shown.

[0073] There are two methods to eliminate the problematic oscillating loops caused by excessive flow due to undersized volume or oversized valves. First, oscillations can be eliminated by modifying the device's PID settings. If the downstream volume is correctly specified, but the controlled pressure is unstable or oscillating, the PID value may be set too high and needs adjustment. Both proportional and integral settings need to be reduced or decreased until the anomaly disappears; however, this adjustment is only effective within a relatively small window. Beyond this window, instability will occur, adversely affecting accuracy and resolution. Second, reducing the orifice diameter of the pressure sensing line can prevent excessive air from passing through the pressure sensing element, thus mitigating overshoot and undershoot. However, the physical principles of fluid dynamics dictate the speed of compressed gas through a specified path; an excessively small orifice diameter will inevitably prolong the time required to obtain accurate pressure values, thus extending the filling time.

[0074] It is evident that the hardware structure of the electro-proportional valve, determined based on low-flow, high-frequency pneumatic applications, will greatly increase the difficulty of adjustment if it does not match the adjustable window of the PID parameters, making it difficult to simultaneously meet the requirements of low flow, high response speed, and stability to suppress oscillations.

[0075] Therefore, this application provides a novel electro-proportional valve through embodiments, which makes corresponding structural improvements to address the causes of the above-mentioned problems, so as to achieve accurate, rapid and stable tracking of target air pressure in low-flow application scenarios. [Specific Implementation Example 1]

[0077] Figure 6 This is a schematic diagram of the structure of the electro-proportional valve 1 provided according to a specific embodiment of this application. Figure 7 The gas pipeline section was magnified for display.

[0078] like Figure 6 , Figure 7 As shown, compared with the existing electro-proportional valve 1', the electro-proportional valve 1 provided in this application also has a vent pipe 5 in the valve body. One end of the vent pipe 5 is connected to the outlet pipe 3, and the other end is connected to the external environment, forming a gas passage that can discharge a portion of the gas in the outlet pipe 3 to the external environment.

[0079] Further, refer to Figure 7 The location where the vent pipe 5 connects to the outlet pipe 3 is closer to the inlet pipe 2 than the location where the pressure measuring pipe 31 connects to the outlet pipe 3. (Observation) Figure 7As can be seen from the airflow direction in each pipeline, during the process of the airflow f_2 in the intake pipeline 2 being proportionally output to the exhaust pipeline (forming airflow f_3) and the venting pipeline 5 (forming airflow f_4), before the airflow f_3 encounters the pressure measuring pipeline 31 and is diverted from the airflow f_31 entering the pressure measuring pipeline, a portion of it is discharged to the external environment in the form of airflow f_5 through the venting pipeline 5. In this way, without changing the diameter of the pressure measuring pipeline 31 to avoid prolonging the pressure measurement response time, the impact and airflow debris generated when the airflow enters the pressure measuring pipeline 31 at low flow rates can be significantly reduced, enabling the pressure sensor 33 to quickly and accurately obtain the true pressure value in the exhaust pipeline 3.

[0080] Figure 8 The diagram illustrates the pressure changes in the outlet pipe 3 when the electro-proportional valve 1, with the aforementioned vent pipe 5 structure incorporated, controls the outlet flow. A comparison is then made. Figure 5 and Figure 8 It can be seen that this structure, which reduces the amount of gas involved in closed-loop feedback control in the exhaust pipe 3 and discharges a portion of the gas in the exhaust pipe 3 to the external environment, can address the root cause of the problem and fundamentally improve the problem of tracking air pressure oscillation in pneumatic application scenarios with low flow and fast response.

[0081] Preferably, the diameter of the vent pipe 5 is set to be significantly smaller than the diameter of the outlet pipe 3 and / or the exhaust pipe 4, for example, less than 1 / 10 of the diameter of the outlet pipe 3 and / or the exhaust pipe 4, or even smaller, so that the maximum airflow of the vent pipe 5 is much smaller than the maximum airflow of the outlet pipe 3 and / or the exhaust pipe 4, in order to avoid the problem of insufficient airflow not participating in closed-loop feedback control in low-flow start-up application scenarios. [Specific Implementation Example 2]

[0083] Figure 9 This is an enlarged schematic diagram of the gas pipeline portion of the electro-proportional valve 1 provided according to a specific embodiment two of this application. The following only refers to the embodiment one ( Figure 7 The structure of different parts of the ) will be described, and the structure of other parts not mentioned will be similar to that of the ) Figure 6 The structures shown are the same.

[0084] Comparison Reference Figure 9 and Figure 7It can be seen that the difference between the electric proportional valve 1 provided in specific embodiment 2 and the electric proportional valve 1 provided in specific embodiment 1 lies in the setting of the vent pipe 5. Specifically, it connects the outlet pipe 3 and the exhaust pipe 4, and the position of the connection with the exhaust pipe 4 is also closer to the inlet pipe 2 than the position of the connection between the air pressure measuring pipe 31 and the outlet pipe 3. That is, the vent pipe 5 shares the exhaust pipe 4, so that the airflow flowing through the outlet pipe f_3 enters the exhaust pipe 4 through the vent pipe 5 before entering the air pressure measuring pipe 31, and merges with the airflow that originally flowed into the exhaust pipe due to the opening of the second piston 172 to form airflow f_4' which flows out to the external environment.

[0085] Using the vent pipe 5 structure shown in Specific Embodiment 2, it can be seen that even if the second piston 172 is completely closed, there is still airflow f_4' in the exhaust pipe due to the presence of the vent pipe 5. [Specific Implementation Example 3]

[0087] Figure 10 This is an enlarged schematic diagram of the gas pipeline portion of the electro-proportional valve 1 provided according to a specific embodiment three of this application, for comparison. Figure 10 and Figure 7 , Figure 9 As can be seen, in the third specific embodiment, the end of the vent pipe 5, that is, the end connected to the external environment, is provided with an opening and closing valve 61 for switching the opening and closing state. By setting the opening and closing valve 61, the applicable application scenarios of the electro-proportional valve 1 can be effectively expanded. For example, when the electro-proportional valve 1 is applied to pneumatic working scenarios with large flow or low response speed, and the oscillation problem is not significant, the vent pipe 5 can be closed to avoid additional airflow loss. [Specific Implementation Example 4]

[0089] Figure 11 This is an enlarged schematic diagram of the gas pipeline portion of the electro-proportional valve 1 provided according to specific embodiment four of this application. The difference between specific embodiment four and specific embodiment three is that the valve at the end of the vent pipeline 5 is replaced with a flow regulating valve 62. The flow regulating valve 62 can be implemented in various ways known to those skilled in the art, such as a knob type or an electrically controlled regulating type. Through the flow regulating valve 62, the flow rate of the gas flow f_5 from the vent pipeline 5 to the external environment can be dynamically adjusted between 0 and its maximum flow rate according to the working state of the electro-proportional valve 1, thereby achieving a better oscillation suppression effect. [Specific Implementation Example 5]

[0091] Figure 12This is an enlarged schematic diagram of the gas pipeline portion of the electro-proportional valve 1 provided according to a specific embodiment 5 of this application. In this embodiment, the number of venting pipelines 5 is increased to two. In addition, in some other embodiments, the number of venting pipelines can be increased to three, four or even more.

[0092] In addition, it can also be like Figure 10 or Figure 11 As shown, different flow regulating valves 62 or on / off valves 61 are set for different venting pipelines 5. Multiple venting pipelines 5, in conjunction with different flow regulating or on / off valves, can flexibly adjust the venting volume over a wider range, thereby meeting the pressure oscillation suppression requirements in more application scenarios. [Specific Implementation Example Six]

[0094] Figure 13 The enlarged schematic diagram of the gas pipeline section of the electro-proportional valve 1 provided according to the sixth embodiment of this application shows that, by comparing this embodiment with the aforementioned embodiments, in the sixth embodiment, a buffer cavity 7 is added to the vent pipeline 5. Preferably, the volume of the buffer cavity 7 is much larger than the volume of the vent pipeline 5 (i.e., the product of the cross-sectional area of ​​the vent pipeline 5 and its length). Adding the buffer cavity 7 can serve as an energy storage unit, reducing flow velocity fluctuations and maintaining stable gas pressure when the flow rate changes abruptly, and can also reduce the impact of pressure fluctuations on the valve. [Specific Implementation Example Seven]

[0096] Figure 14 This is a schematic diagram of the overall structure of an electro-proportional valve according to a specific embodiment seven of this application. Figure 15 This is an exploded structural diagram of an electro-proportional valve according to a specific embodiment seven of this application, as shown below. Figure 14 , Figure 15 As shown, an electro-proportional valve includes a valve body 11 and a control box 14 mounted on the valve body 11. A control unit 12 is housed within the control box 14. The valve body 11 has an air inlet 1.1, an air outlet 1.2, and an exhaust outlet 1.3 arranged circumferentially thereon. The air inlet 1.1 is the port connecting the air inlet pipe 2 to an air source. The air outlet 1.2 is the port connecting the air outlet pipe 3 to a load. The exhaust outlet 1.3 is the port connecting the exhaust pipe 4 to the external environment. The air inlet 1.1 and the air outlet 1.2 are arranged opposite each other, and the exhaust outlet 1.3 is arranged on one side between the air inlet 1.1 and the air outlet 1.2, so that the air intake direction of the air source at the air intake pipe 2 is parallel to the air outlet direction flowing towards the load at the air outlet pipe 3, and the air inlet 1.1 and the air outlet 1.2 are connected through the air intake valve port 1.11, and the air intake direction of the air source at the air intake pipe 2 is perpendicular to the exhaust direction of the exhaust pipe 4 flowing towards the external environment.

[0097] Furthermore, a vent pipe 5 is provided on the other side between the air inlet 1.1 and the air outlet 1.2. One end of the vent pipe 5 is connected to the external environment, and the other end is connected to the air outlet pipe 3. The port of the vent pipe 5 connected to the external environment is a pressure relief hole 1.4. The maximum air flow rate discharged by the vent pipe 5 through the pressure relief hole 1.4 is much smaller than the maximum air flow rate of the air outlet pipe and / or the exhaust pipe, so as to avoid the problem of insufficient air output caused by too much airflow not participating in the closed-loop feedback control in low-flow start-up application scenarios.

[0098] In some preferred embodiments, the venting pipe 5 discharges a portion of the gas in the outlet pipe 3 to the external environment before the gas pressure in the outlet pipe 3 is measured. This allows the venting pipe 5 to discharge a portion of the gas in the outlet pipe 3 to the external environment in a way that reduces the amount of gas participating in closed-loop feedback control. This reduces the impact and airflow debris generated when the airflow enters the pressure measurement pipe at low flow rates, enabling the pressure sensor to quickly and accurately obtain the true gas pressure value in the outlet pipe. Consequently, it can significantly reduce the gas pressure oscillation phenomenon in the outlet pipe under low flow rate and high frequency switching gas demand scenarios.

[0099] Specifically, Figure 16 This is a cross-sectional schematic diagram of an electro-proportional valve provided according to a specific embodiment seven of this application. Figure 17 The diagram shows a cross-sectional view of an electro-proportional valve provided according to a specific embodiment seven of this application. The valve body 11 includes a main valve body 111, a bottom cover 112 disposed at the bottom of the main valve body 111, an intermediate valve body 113 disposed at the top of the main valve body 111, and a pilot seat 114 disposed on the intermediate valve body 113. The control box 14 is covered on the pilot seat 114. A diaphragm 153 is pressed between the pilot seat 114 and the intermediate valve body 113. The diaphragm 153 is connected to the upper end of the valve stem 16 and divides the chamber between the pilot seat 114 and the intermediate valve body 113 into two non-communicating spaces, namely an upper chamber 151 and a lower chamber 152.

[0100] In some preferred embodiments, the valve body 1 internally houses a valve core drive assembly, which includes a valve stem 16, a diaphragm 153 connected to the top of the valve stem 16, a convex ring 161 sleeved on the valve stem 16, and a first valve core 17' and a second valve core 17" located at both ends of the valve stem 16, with the second valve core 17" located below the diaphragm 153. The bottom end of the valve stem 16 passes through the intermediate valve body 113 and extends to the bottom of the main valve body 111. The second piston 172 of the second valve core 17" is limited to the intermediate valve body 113. Between the lower end face of the chamber of the valve body 113 and the convex ring 161, the two cooperate to form an exhaust valve port 1.12. The second valve core 17” is provided with a second spring 182. The first valve core 17’ is provided as an intake valve core between the main valve body 111 and the bottom cover 112. The first piston 171 of the first valve core 17’ is limited to the lower end face of the bottom of the main valve body 111. The two cooperate to form an intake valve port 1.11. The first valve core 17’ is provided with a first spring 181 that drives the first piston 171 to close the intake valve port 1.11.

[0101] Furthermore, the air inlet 1.1 and the air outlet 1.2 are located opposite each other on the side of the main valve body 111. When the air inlet valve 1.11 is open, the air inlet 1.1 and the air outlet 1.2 are connected through the first partition 110. It should be noted that if the exhaust valve 1.12 is closed, the first partition 110 is not connected to the exhaust port 1.3. Only when the exhaust valve 1.12 is open will the gas in the first partition 110 continue to flow upward to the second partition 119 and be discharged through the exhaust port 1.3.

[0102] In some preferred embodiments, the exhaust port 1.3 is located on the side of the main valve body 111 and between the air inlet 1.1 and the air outlet 1.2. The air intake direction of the air source at the air intake pipe 2 is perpendicular to the exhaust direction of the exhaust pipe 4 flowing to the external environment. The exhaust port 1.3 is connected to the exhaust valve port 1.12. By adjusting the air volume in the upper chamber 151, the up and down movement of the valve column 16 can be controlled. By adjusting the position of the valve column 16, the opening and closing and the degree of opening of the first valve core 17' at the air inlet valve port 1.11 can be adjusted, thereby realizing the adjustment of the airflow pressure flowing to the air outlet 1.2.

[0103] The following explanation will focus on the specific intake and exhaust adjustment process:

[0104] A branch path leading to the air supply solenoid valve 141 is provided above the air inlet 1.1. When the air supply solenoid valve 141 is opened, the exhaust solenoid valve 142 is closed. Compressed gas passes through the air inlet branch path above the air inlet 1.1 to the air supply solenoid valve 141, and enters the upper chamber 151 through the air outlet pipe of the air supply solenoid valve 141, pressing down the diaphragm 153. This, in turn, drives the second valve core 17” to press down and open the first valve core 17', opening the air inlet valve 1.11 and connecting the air inlet 1.1 and the air outlet 1.2. At this time, the pressure sensor connected above the air outlet 1.2 detects the pressure signal and outputs secondary pressure.

[0105] When the pressure sensor connected above the outlet 1.2 detects an overshoot in the gas pressure, the control unit 12 closes the supply solenoid valve 141 and opens the exhaust solenoid valve 142. The gas in the upper chamber 151 is discharged to the external environment through the exhaust solenoid valve 142 and the exhaust hole on the pilot seat 114. At this time, the second valve core 17” moves upward, the exhaust valve port 1.12 opens, and the excess gas is discharged from the exhaust valve port 1.12. At the same time, the first valve core 17’ rebounds and reduces the cross-sectional area of ​​the channel between the inlet 1.1 and the outlet 1.2 until the deviation is zero. Both the supply solenoid valve 141 and the exhaust solenoid valve 142 are closed, and the valve core drive assembly reaches a balance in the new position, thereby obtaining an output pressure proportional to the input signal.

[0106] Throughout the above process, the venting pipe 5 participates in the entire process and always discharges a portion of the gas in the outlet pipe 3 to the external environment by reducing the amount of gas participating in the closed-loop feedback control in the outlet pipe. This is to reduce the impact and generation of airflow debris when the airflow enters the pressure measurement pipe at low flow rates, and to reduce the pressure oscillation phenomenon in the outlet pipe under low flow and high frequency switching gas demand scenarios.

[0107] Therefore, the applicant optimized the location of the vent pipe 5. The vent pipe 5 is located on the side of the main valve body 111. One end of the vent pipe 5 is connected to the external environment, and the other end is connected to the air outlet 1.2 through the first partition 110. Alternatively, the vent pipe 5 is connected to the adjacent side wall between the air outlet 1.2 and the exhaust port 1.3, and is located between the air pressure measuring pipe 31 and the first partition 110. This allows the compressed gas to first expel part of the gas through the vent pipe 5, and then pass through the air pressure measuring pipe 31 to the air pressure sensor 33.

[0108] In some preferred embodiments, if the vent pipe 5 is connected through the adjacent sidewall between the outlet 1.2 and the exhaust port 1.3, a one-way valve 154 needs to be installed on the channel from the outlet to the exhaust port. The valve port of the one-way valve 154 is set facing the exhaust port 1.3 to prevent gas backflow and ensure that the gas flows unidirectionally from the outlet to the exhaust port.

[0109] In some preferred embodiments, when the vent pipe 5 is located on the side of the main valve body 111 and communicates with the air outlet 1.2 through the first partition 110, the vent pipe 5 is also connected to a buffer cavity 7, such as... Figure 18 As shown, the buffer cavity 7 is disposed inside the valve body 11. The volume of the buffer cavity 7 is much larger than the volume of the vent pipe 5. It can be used as an energy storage unit to reduce flow velocity fluctuations and maintain stable air pressure when the flow rate changes suddenly. It can also reduce the impact of pressure fluctuations on the valve.

[0110] In some preferred embodiments, the number of vent pipes 5 is multiple, and the buffer cavity 7 is connected to at least one of the vent pipes 5 inside or outside the valve body 11.

[0111] In some preferred embodiments, a flow regulating valve 62 is connected to the port of the vent pipe 5 that connects to the external environment. The flow regulating valve 62 has a pressure relief hole 1.4. The flow regulating valve 62 can be implemented in various ways known to those skilled in the art, such as a knob type or an electronically controlled type. Through the flow regulating valve 62, the flow rate of the airflow f_5 flowing from the vent pipe 5 through the pressure relief hole 1.4 to the external environment can be dynamically adjusted between 0 and its maximum flow rate according to the working state of the electro-proportional valve 1, thereby achieving a better oscillation suppression effect.

[0112] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An electric proportional valve comprising a valve body and a control unit, the valve body having a gas inlet line connected to a gas source, a gas outlet line connected to a gas consuming load, and a gas exhaust line connected to an external environment, the control unit adjusting the proportion of gas from the gas inlet line to the gas outlet line and the gas exhaust line based on closed loop feedback control, characterized in that: the valve body further has a gas bleed line, the gas bleed line being able to discharge a portion of the gas in the gas outlet line to the external environment in a manner that reduces the amount of gas in the gas outlet line that participates in the closed loop feedback control.

2. The electric proportional valve of claim 1, characterized in that: the maximum gas flow rate of the gas bleed line is much smaller than the maximum gas flow rate of the gas outlet line and / or the gas exhaust line.

3. The electric proportional valve of claim 1, characterized in that: the gas bleed line reduces the amount of gas in the gas outlet line that participates in the closed loop feedback control by discharging a portion of the gas in the gas outlet line to the external environment before the gas pressure in the gas outlet line is measured.

4. The electric proportional valve of claim 3, characterized in that: the control unit adjusts the proportion of gas from the gas inlet line to the gas outlet line and the gas exhaust line based on closed loop feedback control by comparing the difference between the gas pressure in a gas pressure measurement line and a target gas pressure, wherein the gas pressure measurement line is in communication with the gas outlet line; and the gas bleed line is in communication with the gas outlet line at a location that is closer to the gas inlet line than the location at which the gas pressure measurement line is in communication with the gas outlet line.

5. The electric proportional valve of claim 1, characterized in that: the number of gas bleed lines is greater than or equal to two.

6. The electric proportional valve of claim 1, characterized in that: further comprising an on-off valve for switching the communication state of at least one of the gas bleed lines with the external environment.

7. The electric proportional valve of claim 1, characterized in that: further comprising a flow rate adjustment valve for adjusting the gas flow rate of at least one of the gas bleed lines to the external environment.

8. The electric proportional valve of claim 1, characterized in that: one end of the gas bleed line is in communication with the gas outlet line and the other end of the gas bleed line is in communication with the gas exhaust line, and the gas bleed line is able to discharge a portion of the gas in the gas outlet line to the external environment even when the passage between the gas exhaust line and the gas inlet line is completely closed by a valve.

9. The electric proportional valve of any one of claims 1 to 8, characterized in that: further comprising a buffer cavity disposed inside the valve body and in communication with at least one of the gas bleed lines inside the valve body or outside the valve body.

10. The electric proportional valve of claim 9, characterized in that: the volume of the buffer cavity is much larger than the volume of the gas bleed line.

11. The electric proportional valve of claim 4, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The valve body is provided with an air inlet, an air outlet and an exhaust port arranged along the circumference thereof, the air inlet direction of the air inlet pipeline is parallel to the air outlet direction of the air outlet pipeline, and the exhaust direction of the exhaust pipeline is perpendicular to the air inlet direction of the air inlet pipeline; Another side surface between the air inlet and the air outlet is provided with a gas discharge pipeline, one end of the gas discharge pipeline is in communication with the external environment, and the other end is in communication with the air outlet pipeline.

12. The electric proportional valve according to claim 11, characterized in that: The gas discharge pipeline is in communication with the air outlet through the first cavity, or the gas discharge pipeline is connected to the side wall adjacent to the air outlet and the exhaust port, or the gas discharge pipeline is connected to the side wall adjacent to the first cavity and the exhaust port, and is located between the air pressure measuring pipeline of the air outlet pipeline and the first cavity, and the gas flow after the gas pressure is adjusted by the gas discharge pipeline enters the air pressure measuring pipeline.

13. The electric proportional valve according to claim 12, characterized in that: The valve body accommodates a valve core driving assembly, and the lower part of the valve core driving assembly is accommodated in the first cavity; The valve core driving assembly comprises a valve column, a diaphragm connected to the top of the valve column, a convex ring sleeved on the valve column, and first and second valve cores located at both ends of the valve column, and the second valve core is located below the diaphragm, the convex ring limits the second valve core, the bottom end of the valve column extends to the bottom of the main valve body through the intermediate valve body, the second piston of the second valve core is limited between the lower end face of the cavity of the intermediate valve body and the convex ring, and the two form an exhaust valve port in cooperation, and the second valve core is provided with a second spring; The first valve core is arranged as an air inlet valve core between the main valve body and the bottom cover, the first piston of the first valve core is limited by the lower end face of the bottom of the main valve body, and the two form an air inlet valve port in cooperation, and the first valve core is provided with a first spring for driving the first piston to close the air inlet valve port.

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